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# How to help compiler do pipelining?

I don't mean compiler flags for pipelining. I would like to program in a way that helps the compiler do optimizations using pipelining. I mean I want to order instructions in C in such a way that GCC (or other compiler) can easily pipeline my instructions. For example, if I have:

a+=b
c=a/b
d+=b
f+=b

Here, the last two 'add' operations would be pipelined, but not the first. I would turn it into:

a+=b
d+=b
f+=b
c=a/b

Notice that the three 'add' operations can be pipelined, but the floating point division cannot.

I want to know, is there more cases in which I can help the compiler do pipelining optimizations? What operations are the ones that can be generally pipelined in modern processors, and that compilers can recognize in code?

• Please suggest a definition of pipelining to use with this question and upcoming answers. (In the first case, a+=b;c=a/b+1; d+=b; f+=b can (in case of the first two, must) be started synchronously.) – greybeard Mar 9 at 7:07
• Compilers can and will optimize your code. And an out-of-order processor will reorder instructions into an optimal way anyway. For example, each core in your iPhone can have a few hundred instructions scheduled for execution and will pick whichever instructions are ready. Write instructions in the way that is most readable. – gnasher729 Mar 9 at 18:20


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### Sample codes... :)

Pages: 12
hi! i want to make a program that will input 5 student names and will input 4 grades for each student then will output the student name with the average of his/her grade using 2d array... this is what i've come up with so far...
 12345678910111213141516171819202122232425 #include #include using namespace std; main() { string studentgrade[5][4]; string row, col; int r, c; for (r = 0; r < 5; r++) { cout << "enter name of student: " << r + 1 << endl; getline(cin,row); for (c = 0; c < 4; c++) { cout << "enter grade for student: " << r + 1 << endl; getline(cin,col); } cout<

it doesn't run... at all... i'm having a hard time making it... i'm new at this... please help! :(

this is the sample given to us by our instructor...

 123456789101112131415161718192021222324252627282930313233343536373839404142 #include using namespace std; main() { string name[5]; string term[4] = {"Prelim","Midterm","Semi-Final","Final"}; string grade1[4]; cout<<"Enter the name of the student:\n\n"; for(int i=0;i<5;i++) { cout<<"Enter the name of student "<>grade1[i]; } cout<<"\n\nGrade for student named "<

it's not really complete...
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closed account (Dy7SLyTq)
first you need #include <string>
second make a function that computes the average
ok here's the thing... i'm really new with c++... my programming 1 used java... and i took a break from school for 2 years... didn't really practice any of my programming skills... i don't know a lot of the commands used in c++... so i'm really having a hard time...
can you see the 2 lines on top? the ones starting with ( #include ), those are called include directives.
the cout word is an object defined in the "iostream" header, so if you want to use cout, you shall "include" the iostream header to be compiled into your program.
the same is with string, if you want to use it, you should include a header called string like this:

#include <string>

each directive must be on it's own line.
the includes must be outside the body of anything.
ok... but how do i make a program that will input a student's name then give that particular name it's grade for prelim, midterm, semi-finals and final... 5 students...

and the output will show the student's name and his average grade... using a 2d array...
i'm done! had some help with my classmates...

 12345678910111213141516171819202122232425262728293031323334353637383940414243444546 #include #include #include using namespace std; main() { string student[5]; double grades[5][4]; string term[4] = {"Prelim", "Midterm", "Semi-Final", "Final"}; int i, row, col; double ave[5]; for (i = 0; i < 5; i++) { cout << "Enter Name Of Student #" << i + 1 << ": "; getline(cin, student[i]); } for (row = 0; row < 5; row++) { cout << "Enter Grades for " << student[row] << ":" << endl << endl; for (col =0; col < 4; col++) { cout << term[col] << ": "; cin >> grades[row][col]; ave[row] = ave[row] + grades[row][col]; } cout << endl; ave[row] = ave[row]/4; } for (row = 0; row < 5; row++) { cout << "Name of Student #" << row + 1 << " " << student[row] << endl; for (col = 0; col < 4; col++) { cout << term[col] << ": " << grades[row][col] << endl; } cout << "\nWith an Average of " << ave[row] << endl << endl; } cout << endl; system("PAUSE"); return 0; }
updated version... :)

 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869 #include #include #include using namespace std; main() { string student[5]; string term[4] = {"Prelim", "Midterm", "Semi-Final", "Final"}; int grades[5][4], i, row, col; double ave[5], aveterm[4]; for (i = 0; i < 5; i++) { cout << "Enter Name Of Student #" << i + 1 << ": "; getline(cin, student[i]); cout << endl; } for (row = 0; row < 5; row++) { cout << "Enter Grades for " << student[row] << ":" << endl << endl; for (col =0; col < 4; col++) { cout << term[col] << ": "; cin >> grades[row][col]; } cout << endl; } for (row = 0; row < 5; row++) { for (col =0; col < 4; col++) { ave[row] = ave[row] + grades[row][col]; } ave[row] = ave[row]/4; } for (col = 0; col < 4; col++) { for (row = 0; row < 5; row++) { aveterm[col] = aveterm[col] + grades[row][col]; } aveterm[col] = aveterm[col]/5; } cout << " Student # | Student Name | P || M || S || F || Average" << endl; cout << "-----------------------------------------------------------------------------" << endl; for (row = 0; row < 5; row++) { cout << " " << row + 1 << " | " << student[row] << "\t\t"; for (col = 0; col < 4; col++) { cout << "| " << grades[row][col] << " |"; } cout << "| " << ave[row] << " "; cout << endl; } cout << " | Average per Term\t\t"; for (col = 0; col < 4; col++) { cout << "| " << aveterm[col] << " |"; } cout << "\n-----------------------------------------------------------------------------" << endl; cout << endl; system("PAUSE"); return 0; }
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 123456789101112131415161718192021222324252627282930313233343536373839404142434445 #include using namespace std; main() { int r,c,j=0,i=10,a[10][10]; for(r=0;r<10;r++) { for (c=0;c<10;c++) { a[r][c]=0; } } for(r=0;r<10;r++) { for (c=0;c<10;c++) { cout<0;c--) { cout<<" "; } for(c=r;c

 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647 #include using namespace std; main() { int r,c,j=0,i=10,a[10][10]; for(r=0;r<10;r++) { for (c=0;c<10;c++) { a[r][c]=0; } } for(r=0;r<10;r++) { for (c=0;c<10;c++) { cout<i-2;c--) { cout<

 12345678910111213141516171819202122232425262728293031323334 #include using namespace std; main () { int r, c, a[10][10]; for (r=0;r<10;r++) { for(c=0;c<10;c++) { a[r][c]=0; } } for (r=0;r<5;r++) { for(c=0;c<=r;c++) { cout<0;r--) { for(c=0;c

 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859 #include using namespace std; main() { int r,c,j=0,i=10,a[10][10]; for(r=0;r<10;r++) { for (c=0;c<10;c++) { a[r][c]=0; } } for(r=0;r<10;r++) { for (c=0;c<10;c++) { cout<4;r--) { for(c=i;c>0;c--) { cout<<" "; } for(c=0;c0;r--) { for(c=j-1;c>0;c--) { cout<<" "; } for(c=i+1;c>0;c--) { cout<

 1234567891011121314151617181920212223242526272829303132 #include #include using namespace std; main() { int r,c; string a[10][10]; for(r=0;r<10;r++) { for (c=0;c<10;c++) { a[r][c]="0"; } } for(r=0;r<10;r++) { for (c=0;c<10;c++) { if (r==c) cout<<"* "; else cout<
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 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960 #include using namespace std; main() { int r,c,j=0,i=10,l=0,m=10,a[10][10]; for (r = 0; r < 10; r++) { for (c = 0; c < 10; c++) { a[r][c] = 0; } } for (r = 0; r < 10; r++) { for (c = 0; c < 10; c++) { cout << a[r][c] << " "; } cout << endl; } cout << "\n\n"; for(r=j;r<10;r++) { for(c=j+1;c<10;c++) { cout<<" "; } for(c=r;c>i-2;c--) { cout<0;c--) { cout<<" "; } for(c=r;c
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I would have thought to not try and use one 2d array because names would be a string and grades averages would be dealing with math.

these are not easily compatable. wouldn't it be easier to use structs and then put your structs into an array of structs, if needed?

something like...

 1234567 struct student { string first_name; string last_name; int grades[4]; int gradeAverage; };

this would be my approach.

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 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182 #include using namespace std; main() { int ***wee, l, w, d, i, j, k; cout<<"Enter side of wee\n"; cout<<"l: "; cin>>l; cout<<"\nw: "; cin>>w; cout<<"\nd: "; cin>>d; wee=new int** [l]; cout<>wee[i][j][k]; cout<
 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127 #include using namespace std; int n; struct b { string m; string d; string y; }; struct p { string fn; string mn; string ln; string g; int a; double h; float w; b bd; }; main() { int i, j, h; cout<<"Enter number of students: "; cin>>n; p *s; s = new p [n]; for(i=0; i>s[i].fn; cout<<"Enter the middle name of "<>s[i].mn; cout<<"Enter the last name of "<>s[i].ln; cout<<"Enter the age of "<>s[i].a; cout<<"Enter the gender of "<>s[i].g; cout<<"Enter the birthday of "<>s[i].bd.m; cout<<"Day: "; cin>>s[i].bd.d; cout<<"Year: "; cin>>s[i].bd.y; cout<<"Enter the weight of "<>s[i].w; cout<<"Enter the height of "<>s[i].h; } for(j=n-1; j>0; j--) { for(h=0; hs[h+1].ln) { string t = s[h].fn; s[h].fn = s[h+1].fn; s[h+1].fn = t; string t2 = s[h].mn; s[h].mn = s[h+1].mn; s[h+1].mn = t2; string t3 = s[h].ln; s[h].ln = s[h+1].ln; s[h+1].ln = t3; int t4 = s[h].a; s[h].a = s[h+1].a; s[h+1].a = t4; string t5 = s[h].g; s[h].g = s[h+1].g; s[h+1].g = t5; string t6 = s[h].bd.m; s[h].bd.m = s[h+1].bd.m; s[h+1].bd.m = t6; string t7 = s[h].bd.d; s[h].bd.d = s[h+1].bd.d; s[h+1].bd.d = t7; string t8 = s[h].bd.y; s[h].bd.y = s[h+1].bd.y; s[h+1].bd.y = t8; float t9 = s[h].w; s[h].w = s[h+1].w; s[h+1].w = t9; double t10 = s[h].h; s[h].h = s[h+1].h; s[h+1].h = t10; } } } cout<<"\n\n"; for(i=0; i
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 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152 # include using namespace std; struct student { string fullName; int mathGrade; int physicsGrade; int historyGrade; int cookingGrade; }; int main() { student st[5]; cout << "Load students info" << endl << endl; for(int i=0;i<5;i++) { cout << "==============" << endl; cout << "Student nbr " << i+1 << endl; cout << "==============" << endl; cout << "Enter the whole name -> ";getline(cin,st[i].fullName); cout << "Enter math grade -> ";cin >> st[i].mathGrade; cout << "Enter physics grade -> ";cin >> st[i].physicsGrade; cout << "Enter history grade -> ";cin >> st[i].historyGrade; cout << "Enter cooking grade -> ";cin >> st[i].cookingGrade; cout << endl; cin.ignore(); } cout << endl; // if you want to show all of students info cout << "Display students info" << endl << endl; for(int i=0;i<5;i++) { cout << "==============" << endl; cout << "Student nbr " << i+1 << endl; cout << "==============" << endl; cout << "Enter the whole name -> " << st[i].fullName << endl; cout << "Enter math grade -> " << st[i].mathGrade << endl; cout << "Enter physics grade -> " << st[i].physicsGrade << endl; cout << "Enter history grade -> " << st[i].historyGrade << endl; cout << "Enter cooking grade -> " << st[i].cookingGrade << endl << endl; } return 0; }

I hope that helps
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manga and techno1... thanks... it really did help... it made the program simpler and a lot easier to manipulate the data... :)
You're welcome dont forget to mark it as solved(It realy helps this community!)
if i "mark it as solved"... will i still be able to post here?...
closed account (Dy7SLyTq)
yeah
 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950 #include using namespace std; struct s{ int x; int y; int add(int a, int b) { int r; r=a+b; return (r); }; int sub(int a, int b) { int r; r=a-b; return (r); }; double mul(double a, double b) { double r; r=a*b; return (r); }; float div(float a, float b) { float r; r=a/b; return (r); }; }; main() { s op; cout<<"enter value for x: "; cin>>op.x; cout<<"enter value for y: "; cin>>op.y; cout<<"\n\n"; cout<<"\nAddition: "<
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 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180 #include #include #include using namespace std; string en(string x) { for(int i=0;i
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closed account (Dy7SLyTq)
omfg... we must kill all necromancers kel' thuzad style. ill grab a hammer
Pages: 12

format: plain


text:
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## Thursday, November 11, 2010 ... //

### Pogrom against German climate realists

Seventy-two years ago, on November 9th-10th, 1938, German Jews and their assets were attacked throughout Germany in an event known as the Crystal Night.

This old kind of fascism is dead in the country - at least in the mainstream - but other kinds of fascisms are only beginning to thrive. To commemorate the anniversary, the Green fascists in the Parliament have launched an assault against all German climate realists:

Grüne machen mit Klimakatastrophen-Zweiflern den Sarrazin (Die Achse des Guten)

Automatic translation to English

No Tricks Zone's report (Pierre Gosselin)

Germany gets ugly with climate skeptics (Anthony Watts)
A letter not too tastefully titled "Deniers of climate change in the coalition government" (it used to be "Jewish elite spoiling the Aryan lives") signed by the whole Parliamentary faction of the Greater Green Party was sent to the government one week ago.

In the letter, the green people complain that the influence of climate skepticism is rising in the U.S. as well as Germany where some people even dare to listen to Fred Singer. Imagine the crime! ;-)

Thanks to Pierre Gosselin for the most usable translation of the green theses.

To fight the trend, Ms Renate Künast, Mr Jürgen Trittin and "friends" are "asking the federal German government":
1. Is the German Government aware of a scientifically published paper that has been subjected to peer review that questions climate change caused by man, and that is supported by scientific data?
I am not sure whether the German government dares to know but if they do, they can also point out this list of 800 peer-reviewed papers that fits the description above. Of course, some of the papers were also co-authored by Fred Singer.
2. In the view of the German Government’s Leadership, is there a scientific discussion on whether climate change is taking place and whether man has a decisive impact on climate?
You bet. Your own Kristallnacht letter is another piece of evidence that the discussion is boiling more than ever before. Right now, it seems more likely that the answer to the question about man's major influence is pretty much No.
3. Is the German Government aware of the publications from American physicist Fred Singer on the subject of climate protection? How does the German Government view the scientific reputation of Mr Singer in regards to climate protection?
Again, I don't know whether the German government has any clue about these topics. My own guess is that the German Government is dominated by ignorants who simply have no idea about these matters. But yes, they should know him and his work because it is important.

By the way, it's nonsensical to describe papers about the drivers of the climate as papers about "the subject of climate protection". Climate protection has no room in science - it belongs to extremist advocacy groups. Science is about learning how things work, not about designing orthodoxies how things such as the climate should be "protected".
4. For the German Government, do the arguments made by Fred Singer and other arguments presented have merit and are they “enlightening”? How do you assess the statements by Mr Singer that “Politicians that are embedded in climate change are more dangerous than climate change itself”?
If they dared to hear them, the arguments would surely make lots of sense. But the government would also have to be courageous enough to say so. Surrounded by lots of green fascists, I am afraid that those hypocritical German politicians are cowards. Moreover, admitting that they - the politicians - are more dangerous than the imaginary threats would also be somewhat suicidal and it needs a special courage for a politician to admit so.
5. Is the German Government aware of the ideas Mr Singer has previously promoted? What’s your view on the fact that he, for example, questioned the hazards of passive smoke, or that he contested the ozone layer was damaged by CFCs, or that he trivialized acid rain? With this background, how does the German Government judge the credibility of Fred Singer’s activities with regards to climate protection?
It got a little bit too personal, right? The hazards of passive smoke or the mechanisms controlling the ozone layer remain covered by uncertainty; see e.g. Ozone hole theory faces lab problems. However, even if someone managed to be convinced that everything is settled, these questions have nothing to do with another question - about man-made climate change.

There are clearly lots of AGW skeptics who believe that the passive smoking and freons are harmful. I've seen the effects of acid rains and hated them. But of course, people have different opinions about various complex matters. How the German government could possibly judge Singer's credibility about EF because of his opinions about AB and CD remains incomprehensible to me. Moreover, they just take Fred Singer out of context. He's surely neither the only climate skeptic nor the ultimate template that all climate skeptics are obliged to reproduce. (Sorry, Fred.)

What these Green fascists want is to attach a new yellow star to Fred Singer's skin - and to the skin of anyone who has ever met him and exchanged some information or friendly sentences. I am honored to belong to this group of people so you can't be surprised that I am personally offended by this outrageous attempted witch hunt.
6. Is the German Government aware of who financed Mr Singer for his activities? Is the Federal Government aware of the funders who -like Exxon und Koch Industries in the USA - fund the activities of the climate change deniers in Germany?
I suppose that as a professor emeritus of environmental science at the University of Virginia, he is getting the same salary as other - especially distinguished - emeritus professors. I am sure that green fascists are probably not happy but the institutionalized science works in this way and Fred Singer deserves much more than he is getting from that system.

Fred Singer is an amazingly active Gentleman so he may also have other sources of income - such as speaking fees. At any rate, the exact composition of Fred Singer's wallet is clearly not the green folks' business. By the way, lots of big corporations - including oil companies - as well as governments pay lots of money to various green groups. This is what should be investigated if anything should.
7. Does the German Government share the opinion that events with Mr Singer provide a forum for the pure interests of the fossil fuel industry, and thus enhance their unscientific work and unserious activities?
Haven't they already said the same childish thing about Big Oil before? Do they think that if they repeat a vitriolic comment about the "fossil fuel industry" several times, it becomes less essential?

The fossil fuel industry is an essential sector of the economies of the modern societies. If the fossil fuel industry were liquidated, it would be incomparably more harmful to the mankind than if all members and apologists for the climate hysteria movement were made to disappear overnight. So why do the latter feel so much self-confident in their irrational attacks?

However, it's just the truth that virtually no part of the climate skepticism has any direct links with the "fossil fuel industry". I have no such links and I am sure that most people who actually matter don't have any such links, either. On the other hand, the relationships in the world are complicated so it's statistically guaranteed that some skeptics have some links of this kind, much like the other side has. And what?

Do those green folks think that just by finding someone in a big group who has some contacts to a large group of people - which arguably includes the majority of the world population - they can discredit this group? Or why do they keep on repeating these irrational and insulting incantations? Such remote links may impress the voters of the German Green Voters because those people are unable to think. But these labels can't make a (positive) difference among the rational people.
8. Are there voices within the German Government who question the anthropogenic causes of climate change?
You bet. But do the green comrades also want their addresses so that they could "confront" them? You can't do it. About 1/2 of the politicians actually disagree with the alarmist ideology although most of those in Germany remain silent. Even if you were given all the names, you couldn't do anything because there would be too many of them.
9. How does the German Government view the activities of the European Institute for Climate and Energy (EIKE) with regards to climate change? EIKE is supported by Fred Singer. In the Federal Government’s view, does the Institute work on the scientific question regarding the subject of climate change?
I am baffled by the idea that the German government should have common attitudes to detailed questions about life such as "the activities of EIKE". It's clearly just one institute doing things that are, to say the least, 100% legal. Do the Green comrades expect the government to promise a 100% loyalty to the One Thousand Year Green Empire? Should the government vow to fight against everyone who is not a perfectly green mouldy piece of scum?

I personally praise the work of EIKE and I am sure that most decent German politicians praise it, too.
10. Is the German Government aware of whether climate denier conferences are also being financed by public funds, for example by the Liberal Institute of the Friedrich-Naumann-Foundation?
They're not called "denier conferences": they're the only proper conferences about key climate change drivers on the German territory. Not sure whether they are also funded by public funds but they surely should - unlike the crooks in the Green Party.
11. In general, does the German Government approve of the use of public funds for spreading the ideas of climate deniers like Fred Singer?
Clearly, public funding for science should be ideologically neutral, so if there are funds going to people whose conclusions are convenient for the Green fascists, there must also be a public funding for the equally achieved researchers whose conclusions are inconvenient.

I am more interested in the question whether the German Government still intends to protect basic human rights, privacy, and ideologically neutral attitude of the government to its citizens and corporations.

In particular, will the government do its best to protect the life, assets, and dignity of the institutions and people who are being threatened and blackmailed by this letter? Will the German policemen shoot quickly enough to neutralize the green radicals once they switch from disgusting verbal attacks to physical attacks?

The German environmentalism has showed to be on the same path as the German national socialism in the late 1930s and it's time for the German Government to take notice of this inhuman and aggressive movement.


text:
# Quantum harmonic oscillator

1. Sep 12, 2009

### kof9595995

2. Sep 12, 2009

### xepma

The kinetic energy is at a minimum when the momentum is precisely zero. On the other hand, the potential energy is at a minimum when the coordinate x is precisely zero. But they cannot be zero at the same time - Heisenberg's uncertainty principle forbids it. So instead we replace the quantities by their "fluctuation" around the values $$x=0$$ and $$p=0$$. The fluctuations are just $$\Delta p$$ and $$\Delta x$$. Heisenberg's uncertainty principle simply states that these fluctuations (or uncertainties) are related by:

$$\Delta p\Delta x \geq \hbar/2$$

Which again tells us that the fluctuations cannot both be zero at the same time. If we set the momentum precisely zero (so also no fluctuations) then the kinetic energy is zero as well. But then the fluctuations of the position blows up, and the potential energy does so too. So the situations where the momentum is precisely zero certainly does not correspond to the minimum energy.

If I'm not clear enough, just let me know :)

3. Sep 12, 2009

### kof9595995

Well，thanks. But I'm still confused, because as far as I can understand, even around p=0 $$\Delta p\$$ is not p, uncertainty is the standard deviation of the measurements ,right? so when uncertainty is $$\Delta p\$$, the p can still much smaller than $$\Delta p\$$ , so why can't the actual energy be smaller than that?

4. Sep 12, 2009

### kof9595995

I think something is wrong with my latex code, please just ignore the funny brackets after delta p

5. Sep 12, 2009

### Snarky Fellow

Well, around p=0 one needs to distinguish $$\Delta p$$ and p, but in fact we are interested only in $$\langle p^2 \rangle$$ that is equal to $$\langle\Delta p^2 \rangle$$ in case the mean momentum is 0.

6. Sep 12, 2009

### kof9595995

So the so called minimum energy is still under the statistical meaning, right?

7. Sep 12, 2009

### kof9595995

Snarky Fellow, is this your first post? Welcome to the forum!

8. Sep 12, 2009

### elduderino

$$E = \frac{{{(p+\Delta p)^2}}}{{2m}} + \frac{1}{2}m{\omega ^2}{(x+\Delta x)^2}$$

For minimum energy, you would classically put p=0 and x=0. Which is what you do above, only that there are uncertainties associated with p and x and the Heisenberg principle does not allow them to be simultaneously zero. For example, if $$\Delta p=0$$ then $$\Delta x$$ would blow up- which does not correspond to the minimum energy.

9. Sep 13, 2009

### kof9595995

Actually in harmonic oscillator <p> should be always 0 because of the symmetry, so $$\langle p^2 \rangle$$=$$\Delta p$$, am I right?

10. Sep 13, 2009

### kof9595995

This formula does not seem quite right to me; I think it should be just
$$E = \frac{{\left\langle {{p^2}} \right\rangle }}{{2m}} + \frac{1}{2}m{\omega ^2}\left\langle {{x^2}} \right\rangle$$
And what Snarky fellow said is why we can substitute $$\Delta p^2$$=$$\langle p^2 \rangle$$

11. Sep 13, 2009

### Snarky Fellow

If we deal with an eigen-state of hamiltonian, which is static in some sense, than due to the symmetry the mean momentum will be equal to zero - you're right. Of course, we can take any superposition of eigen-states, where the symmetry could be broken by our choice, but it's out of interest in this problem.

To say honestly, the derivation of minimal energy using the uncertainty principle isn't very strict - it's just an assessment. It proves only that the minimal energy cannot be less than that we've found. The fact they're equal is a mere coincidence. As far as I know, it works only in the case of a harmonic potential. Usually states with a well-determined energy are not the states with the least uncertainty. Thus a good derivation involves ladder-operator technique or solving the Schroedinger's equation. So I suppose, the main idea of this derivation is to show that classical solution in the bottom of the potential condradicts the uncertainty principle.

12. Sep 13, 2009

### kof9595995

I think I get the idea, thanks.


text:
# Towards $\overline{B}\to {X}_s\gamma$ at the NNLO in QCD without interpolation in m$_{c}$

Misiak, Miko-laj; Rehman, Abdur 1; Steinhauser, Matthias 1
1 Institut für Theoretische Teilchenphysik (TTP), Karlsruher Institut für Technologie (KIT)

## Abstract:

Strengthening constraints on new physics from the $\overline{B}\to {X}_s\gamma$ branching ratio requires improving accuracy in the measurements and the Standard Model predictions. To match the expected Belle-II accuracy, Next-to-Next-to-Leading Order (NNLO) QCD corrections must be calculated without the so-far employed interpolation in the charm- quark mass m$_{c}$. In the process of evaluating such corrections at the physical value of mc, we have finalized the part coming from diagrams with closed fermion loops on the gluon lines that contribute to the interference of the current-current and photonic dipole operators. We confirm several published results for corrections of this type, and supplement them with a previously uncalculated piece. Taking into account the recently improved estimates of non-perturbative contributions, we find ℬ$_{sγ}$ = (3.40±0.17)×10$^{-4}$ and R$_{γ}$≡B$_{(s+d)γ}$/B$_{cℓ\overline{v}}$ = (3.35 ± 0.16) × 10$^{-3}$ for E$_{γ}$> 1.6 GeV in the decaying meson rest frame.

 Zugehörige Institution(en) am KIT Institut für Theoretische Teilchenphysik (TTP) Publikationstyp Zeitschriftenaufsatz Publikationsmonat/-jahr 06.2020 Sprache Englisch Identifikator ISSN: 1029-8479 KITopen-ID: 1000122716 Erschienen in Journal of high energy physics Verlag Scuola Internazionale Superiore di Studi Avanzati (SISSA) Heft 6 Seiten Art.Nr. 175 Vorab online veröffentlicht am 29.06.2020 Nachgewiesen in DimensionsScopus
KIT – Die Forschungsuniversität in der Helmholtz-Gemeinschaft
KITopen Landing Page


text:
## anonymous one year ago verify cos(x)/(1+sin(x))+(1+sin(x))/cos(x)=2sec(x)

1. triciaal

|dw:1437698487751:dw|

2. DecentNabeel

manipulate the left side $\frac{\cos \left(x\right)}{1+\sin \left(x\right)}+\frac{1+\sin \left(x\right)}{\cos \left(x\right)}$ $\mathrm{Simplify}\:\frac{1+\sin \left(x\right)}{\cos \left(x\right)}+\frac{\cos \left(x\right)}{1+\sin \left(x\right)}:\quad \frac{\left(\sin \left(x\right)+1\right)^2+\cos ^2\left(x\right)}{\cos \left(x\right)\left(\sin \left(x\right)+1\right)}$ $=\frac{\left(1+\sin \left(x\right)\right)^2+\cos ^2\left(x\right)}{\left(1+\sin \left(x\right)\right)\cos \left(x\right)}$ $\mathrm{Use\:the\:following\:identity}:\quad \cos ^2\left(x\right)=1-\sin ^2\left(x\right)$ $=\frac{\left(1+\sin \left(x\right)\right)^2+1-\sin ^2\left(x\right)}{\left(1+\sin \left(x\right)\right)\cos \left(x\right)}$ $\mathrm{Simplify}\:\frac{\left(1+\sin \left(x\right)\right)^2+1-\sin ^2\left(x\right)}{\left(1+\sin \left(x\right)\right)\cos \left(x\right)}:\quad \frac{2}{\cos \left(x\right)}$ $\mathrm{Use\:the\:following\:identity:}\:\cos \left(x\right)=\frac{1}{\sec \left(x\right)}$ $=\frac{2}{\frac{1}{\sec \left(x\right)}}$ $=2\sec \left(x\right)$

3. DecentNabeel

are you understand @tamez1210

4. anonymous

Yes I do thank you!

5. DecentNabeel

wellcome :)


text:
# Risk Management Strategies in Construction Organizations

Shabbab Ajami Alhammadi1, Bassam A. Tayeh2, *, Wesam S. Alaloul3, Tareq J. Salem2
1 Vice Rectorate for Facilities and Operation, Princess Nourah bint Abdulrahman University, Riyadh 11671, Saudi Arabia
2 Department of Civil Engineering, Faculty of Engineering, Islamic University of Gaza, Gaza Strip, Palestine
3 Department of Civil and Environmental Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 32610 Tronoh, Perak, Malaysia

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open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Civil Engineering, Faculty of Engineering, Islamic University of Gaza, Gaza Strip, Palestine; E-mail: btayeh@iugaza.edu.ps

## Abstract

### Background:

Construction projects are among the riskiest businesses due to the number of factors involved that are difficult to control; hence, the popularity of risk management as part of the decision-making process in construction organizations is increasing. Despite the advancements, there are various risks involved that lead to project failure.

### Aim:

Thus, this study aims to assess the risk management strategies in construction organizations in the Gaza Strip, Palestine.

### Methods:

Seventy questionnaires were distributed after subjecting them to pretesting and pilot study that confirmed the validity and reliability of the questions. The target respondents included engineers and consultants from the construction organizations, Ministry of Works and Housing, and international agencies. The questionnaire was retrieved with a 65.71% response rate.

### Results:

Results indicated that the most popular method of risk factor determination in the Gaza Strip is the “checklist” (RII=84%). For tools/methods of risk analysis, relying on experience in the direct assessment is the most prominent, with an RII of 78%. For the methods of avoiding risk before the project implementation, dependence on experience in the work for preparing and planning was ranked highest (having RII of 81.6%). Finally, follow-up on the implementation to avoid rework, with an RII of 77.6%, was ranked highest among other factors of avoiding risk during the construction projects implementation.

### Conclusion:

This study highlights the key risk management strategies that will be beneficial for the construction industry stakeholders to resolve the unwanted risk failures in the construction industry.

Keywords: Risk management, Risk factor, Construction, Decision-making process, Stakeholder, Industry.

## 1. INTRODUCTION

Risk management is an important tool and forms part of the decision-making process in the construction industry [1, 2]. Management of the risk of a project is one of the major roles undertaken by a project manager [3, 4]. The purpose of project risk management is to increase the probability and impact of positive events and decrease the probability and impact of negative events, which can be harmful to the project [5, 6]. In the last decades, research on risk management in the construction industry has developed [2, 7] due to the high number of risks involved in construction projects [8]. Furthermore, the inherent high risk is due to the nature of construction projects that involve many parties, such as designers, owners and contractors, and others [9, 10]. Hence construction projects risks can be analyzed from two different sides. That is, the main stakeholder, decision-maker and project owner in construction projects [11, 12] on one hand, and contractors on the other hand [13, 14]. These two sides may have different experiences and responses regarding project risks, which presents different possibilities of transferring the risk to the other party as the best solution to deal with it [15, 16]. Usually, project risk management involves the use of systems that focus on quantitative risk analysis. However, most of these systems cannot find and control the risks and solve the problems. Brainstorming has been reported as the most famous method of risk identification in the construction industry, and that the qualitative methods of risk evaluation are used more often in preference to semi-qualitative and quantitative methods [17, 18]. Acknowledging this situation, a system was developed to select appropriate techniques for risk management in the construction environment [7]. These techniques comprise decomposition, artificial intelligence, sensitivity analysis, probabilistic analysis, decision trees, and others. In the construction projects, risks could lead to constrainment of primary objectives, i.e., cost, time, quality, and scope, which means additional expenses that translate to a lower return to the client and a loss of revenue for the construction parties [19, 20].

Due to the unstable political situation in the Gaza Strip, Palestine, there is an increasing need to assess the risk management strategies, especially in the construction industry, with the view to evaluating their suitability for the ever-changing political terrain. The construction project is one of the most dangerous and risky fields of work, where it is surrounded by many uncertainties that require management due to the presence of many internal and external factors that affect the process. This study provides an understanding of the difficulties and barriers in risk management faced by the construction organizations in the Gaza Strip, and also offers recommendations to improve project implementation by building infrastructures upon which other sectors depend for effective service delivery, keeping in view the importance of construction industry in national development. Moreover, key risk management strategies that are highlighted in this study will be beneficial for the construction industry stakeholders.

## 2. METHODOLOGY

The determination of the risk management strategies employed by construction organizations in the Gaza Strip is the aim of this study. A study of this nature requires the use of the appropriate tools for data collection, which in most cases is the questionnaire. Both qualitative and quantitative types of data have been analyzed for this study.

The design of the questionnaire was based on information obtained from relevant literature. The relevant questions were obtained from the literature and refined through interviews and pilot survey. The target group of the study included engineers working in construction companies, supervising engineers from international agencies, such as UNDP, UNRWA, Ministry of Public Works and Housing. The purposive sampling technique was chosen for the selection of the sample participants. The purposive sampling is a type of non-probability sampling technique that is most effective when there is a limited number of people that have expertise in the field being researched [21]. Purposive sampling can also be used with quantitative and qualitative research methodology. The inherent bias of the method enhances its efficiency, and the method is strong even when tested against random probability sampling. Choosing the purposive sampling method ensures the quality and reliability of the collected data [21].

### 2.1. The Questionnaire Format

The questionnaire is composed of six parts, each serving as a source for different information from the respondents as follows:

(i) General information about the response person

(ii) General information about the company

(iii) Risk factors

(iv) Determination of risk factor

(v) Avoiding the risk

(vi) Tools for analyzing the risk

The numerical rating scale (five-point Likert scale) was chosen to format the questions with some common sets of response categories called quantifiers (they reflect the intensity of the particular judgment involved) [22]. Those quantifiers were used to facilitate the understanding of the questions.

### 2.2. Face Validity of the Questionnaire

Face validity is very important in determining whether the questionnaire appears to be valid or not. It was presented for evaluation by experts in the risk management field or statistics [23]. The questionnaire was presented to 10 experts by hand delivery at different periods for evaluation. Many useful comments were made and taken into consideration for the modification of the questionnaire.

### 2.3. Semi-Structured Interviews (SSI)

SSI is a verbal or conversational type of interchange where an interviewer tries to elicit information from the interviewee by asking a series of predetermined questions in a normal casual conversation style [24]. The SSI approach was adopted in pretesting of the questionnaires. Pretesting is a very necessary step in a study involving a questionnaire survey. It is an important phase to ensure that all errors related to the survey are reduced or removed completely. It contributes to improving the quality of the data. The pre-testing was carried out in two stages, and each stage was tested with 5 professionals in risk management through the SSI approach. The first stage of the pretesting resulted in modifying some words in the questions, in addition to adding more explanation to some items in order to ensure the understanding of the question. After that, the second phase was implemented, and it was sufficient to ensure the success of the questionnaire, as there were no queries or comments from any professional, and all the questions were clear.

### 2.4. Pilot Study

Pilot research is a trial run for the questionnaire that includes identifying any vague questions, testing the wording of questions, testing the technique which is used to gather the data, etc [22]. The pilot study carried out involved consulting 15 experts in the field of construction and modifying the questionnaire formatting based on their feedback.

### 2.5. Data Collection

The data collection involved distributing the questionnaire to 60 respondents randomly selected from the target population. The last stage involved conducting a statistical test on the questionnaire to determine its reliability and validity.

For the statistical validity test of the questionnaire, two tests were performed: internal validity and structural validity tests. The internal validity test was carried out by measuring coefficients of correlation (Pearson test) between each item in one field and the whole field [25]. P-values were found less than 0.05; hence, the correlation coefficients of each field were found to be significant at α= 0.05. Thus, it can be said that the items in each field were consistent and valid.

The structural validity test measures the coefficient of correlation between one field and all of the other fields of the questionnaire that have the same level of scale rating (five-point Likert scale) [25]. It was found out that the values of significance for all fields were less than 0.05. Accordingly, it can be noted that the fields were valid to be measured. Other tests carried out included the Cronbach’s Coefficient Alpha; the results were in the range from 0.700 and 0.967, and the general reliability for all items equaled 0.962. This range is considered high (above 0.7). Thus, the result ensures the reliability of the questionnaire. Also, using the Half-Split method, the significance of all the field values was found less than 0.05, indicating the corrected correlation coefficients to be significant at α=0.05. As a result, it can be said that the studied fields were reliable.

After all the tests were carried out, and the results indicated the suitability of the questionnaire for the intended study, it was then distributed to the target respondents with a cover letter explaining the purpose of the research and assuring them of the security and privacy of the information to encourage them to respond. Analysis of the data was undertaken using SPSS (Statistical Package for the Social Science).

### 2.6. Respondents’ Profile

The respondents' profile is shown in Table 1. 60 responses (representing a retrieval rate of 65.71%) retrieved from the respondents in the construction industry in the Gaza Strip were evaluated in developing the profile based on six (6) categories of questions.

As can be observed from Table 1 , 70% of the respondents were engineers, 11.7% were directors of the engineering office, 6.7 were project managers, 5% were heads of specialization, 3.3% were assistant heads of specializations, and others accounted for 3.3%. Regarding the respondents’ years of experience in the engineering field, 38.3% of them had less than 5 years of experience while 16.7 had more than 15 years of experience. The educational background information indicated that most of the respondents (73.3%) had a bachelor’s degree, followed by 18.3% with master's, 6.7% with a diploma, and 1.7% had a Ph.D. 35% of the respondents implemented more than 15 projects in the last 5 years, while 26.7% did less than 5. Regarding the years of an engineering office in the field of consultancy, 28.3% had between 5 to less than 10 years of experience, followed by 25% who had from 10 years to less than 15 years of experience. Those having less than 5 and more than 15 years of experience accounted for 23.3%. 31.7% implemented a project worth less than 1$million. 25% implemented a project worth between 1$ million to less than 5$million in the last 5 years while those that implemented between 5$ million to less than 10$million and those more than 10 million accounted for 21.7% each. Table 1. Respondents' background profile frequency and percentage. Job Title Frequency (F) Percent (%) Director of Engineering Office 7 11.7 Projects Manager 4 6.7 Head of specialization 3 5.0 Assistant Head of Specialization 2 3.3 Engineer 42 70.0 Other 2 3.3 Years of experience in the engineering field - - Less than 5 23 38.3 5 - Less than 10 15 25.0 10 - Less than 15 12 20.0 More than 15 10 16.7 Educational level - - Diploma 4 6.7 Bachelor 44 73.3 Master 11 18.3 Ph.D. 1 1.7 Number of projects implemented during the previous 5 years - - Less than 5 projects 16 26.7 5 - Less than 10 13 21.7 10 - Less than 15 10 16.7 More than 15 21 35.0 Years of experience of the Engineering Office in the field of consultancy - - Less than 5 14 23.3 5 - Less than 10 17 28.3 10 - Less than 15 15 25.0 More than 15 14 23.3 Value of projects implemented in the last 5 years - - >$1 million 19 31.7
From $1 to less$5 millions 15 25.0
From $5 to less$10 millions 13 21.7
\$10 million and more 13 21.7

## 3. RESULTS AND DISCUSSION

After subjecting the data to rigorous analysis using the SPSS software, the following results regarding the risk management strategies in construction organizations in the Gaza Strip were obtained.

### 3.1. Identification of Risk Factors Methods

This section reveals the information on the methods used by the construction industries in the Gaza Strip to determine the risk factors. The determination of risk factors is composed of seven methods (DE1 – DE7). The result is presented in Table 2.

Table 2. Determination of risk factors in the construction organizations.
No. Determination of Risk Factor Mean Std. Dev RII (%) T Value P Value
Sig.
Rank
DE1 Checklists 4.20 0.90 84.00 10.35 0.000 1
DE2 In-house brainstorming 3.39 1.05 67.80 2.85 0.006 5
DE3 Opinion of external subject matter experts 3.03 1.19 60.67 0.22 0.829 7
DE4 Site Analysis 3.67 0.93 73.33 5.54 0.000 3
DE5 Analysis of contract documents 3.80 0.97 76.00 6.38 0.000 2
DE6 Case studies 3.57 1.06 71.33 4.13 0.000 4
DE7 Other 3.25 1.30 65.00 1.16 0.255 6

The findings indicated that “Checklists” method (DE1) (RII =84.00%; P-value =0.000; T-value= 10.35; SD= 0.90) had the highest rank (Fig. 1). Since P-value here equaled 0.000 which is less than 0.05, and T statistics = 10.35 > T critical (2.00), the statistically significant differences were attributed to the respondents’ opinions at the level of α ≤ 0.05 between the statistical mean (4.20) and hypotheses mean (3). SD equaled 0.90, indicating that the respondents’ results were consistent and not spread out over a wider range of values. So, it can be said that the results were significant.

 Fig. (1). RII determination of risk factor statements (DE1 to DE7).

The use of a checklist ensures that tasks are monitored and kept on track to avoid deviating from the project plan. Doing that helps in identifying potential risks and taking appropriate steps to avoid them, thereby ensuring timely completion of the project and keeping it within the budget. That is the reason why most companies follow that method and commit to following it for evaluation and to identify any risks that may occur. Because of the prevalent use of the checklist in most of the construction projects in the Gaza Strip, it ranksa as the highest among the other types of methods for risk factor determination.

The results also revealed “Analysis of contract documents” determination of risk factors method (DE5) (RII = 76.00%; P-value = 0.000; T-value = 6.38; SD = 0.97) to be in the second position. Since P-value here equaled 0.000 which is less than 0.05, and T statistics = 6.38 > T critical (2.00), the statistical significant difference was attributed to the respondents’ opinions at the level of α ≤ 0.05 between the statistical mean (3.80) and hypotheses mean (3). Thus, it can be said that the results are valid. Contract documents are signed by all parties involved in the project and are governed by the document. Hence, in case of any dispute that may occur between any of the parties, reference documents are reviewed and conformed to. Consequently, it is very important to have a contract between any two parties obliging them to abide by the articles, which is the only reference and legally adopted and customary in the construction issues. For that reason, any terms agreed upon by the parties in the contract documents shall be documented.

Opinion of external subject matter experts” determination of risk factors method (DE3) (RII = 60.67%; P-value = 0.829; T-value = 0.22; SD = 1.19) was ranked at the last position in this field. Since P-value here equaled 0.829 being greater than 0.05, no statistically significant differences were attributed to the respondents’ opinions at the level of α ≤ 0.05 between the statistical mean (3.03) and hypotheses mean (3). The results were found to be valid. If the solutions to any problem are found internally, in the custom of construction projects, experts from abroad are rarely used, because most of the major engineering companies supervise major projects in the Gaza Strip and have sufficient experience in solving any problem and predicting any risks due to accumulated experience [26-29].

Therefore, it may be noted that the tools mostly used by the construction organizations in the Gaza Strip for the determination of risk factors are the checklist and the contract documents.

### 3.2. Tools/Methods for Analyzing the Risks

In this section, the tools or methods used by the construction organizations for analyzing the risks are discussed. Five tools are listed in Table 3 together with the results of statistical analysis on the data obtained from the respondents.

The findings demonstrated “Relying on experience in the direct assessment” tool (AR4) (RII =78.00%; P-value =0.000; T-value= 7.33; SD= 0.95) with the highest rank (Fig. 2). Since P-value here equaled 0.000 which was less than 0.05, and T statistics = 7.33 > T critical (2.00), a statistically significant difference was attributed to the respondents’ opinions at the level of α ≤ 0.05 between the statistical mean (3.90) and hypotheses mean (3). The results were found to be valid.

In the case of risks, some companies use experts from abroad to assess and analyze these risks, and most often, internal and external committees are formed to take decisions to overcome any risks. In most projects, there exist arbitration committees or advisory committees to whom any problem is referred, and they are expected to find appropriate solutions and provide a safe environment for completing the project activities. The previous experience of similar projects is very important to detect risks that may occur, and the experts can figure out those risks through observation or technical reports. The use of previous experience in the assessment of risk is very common as many construction organizations in the Gaza Strip employ the services of international companies with vast experience to undertake a risk assessment in order to prevent the occurrence of the risks [30-32].

Table 3. Analyzing the Risk tools in the construction organizations.
No. Items Mean Std. Dev RII (%) T Value P Value
Sig.
Rank
AR1 Analyzing by using computer applications 3.63 1.16 72.67 4.22 0.000 3
AR2 Probability analyzing by using information history 3.33 1.04 66.67 2.49 0.016 4
AR3 Analyzing by using simulation programs applications 3.13 1.11 62.67 0.93 0.357 5
AR4 Relying on experience in the direct assessment 3.90 0.95 78.00 7.33 0.000 1
AR5 Analyzing by using similar previous projects 3.85 0.92 77.00 7.18 0.000 2

 Fig. (2). RII analyzing risk tools of statements (AR1 to AR5).

The results also revealed “Analyzing by using similar previous projects” statement (AR5) (RII = 77.00%; P-value = 0.000; T-value = 7.18; SD = 0.92) to rank at the second position.

Often, the problems and risks are repeated in the projects. Some companies benefit from the solutions to those problems in the previous projects and use them in other projects. This is due to the company's experience in executing the construction works and the size of projects implemented beforehand. That is why, some financiers usually require as a prerequisite the experience of the engineering company in similar construction works.

Analyzing by using simulation programs applications” statement (AR3) (RII = 62.67%; P-value = 0.357; T-value = 0.93; SD = 1.11) was ranked as the last in this field. Companies are used to employing traditional methods of risk analysis. Therefore, few companies use computer applications to obtain results for risk analysis, although computer analysis is better and faster and gives more accurate results. This could be because the company needs to train the staff on computer analysis which will lead to financial costs that will, in turn, increase the financial burden of the company. Nevertheless, we suggest that the companies consider the importance of this factor in order to obtain more beneficial results.

### 3.3. Avoiding the Risk

As part of the risk management, construction organizations try to avoid the risk altogether through one or both of the following ways:

(i) Avoiding the risk before the implementation of the project.

(ii) Avoiding the risk during the implementation of the project.

Information retrieved from the respondents on both situations was statistically analyzed and the results are as follows:

### 3.4. Avoiding the Risk before Implementation

For evaluating this, seven items (Av1 to Av7) are used, as shown in Table 4.

The findings indicated that “Dependence on the experience in work for preparing and planning” statement (Av1) (RII =81.60%; P-value =0.000; T-value= 10.12; SD= 0.83) was ranked as the highest (Fig. 3). Since P-value here equaled 0.000 which was less than 0.05, and T statistics = 10.12 > T critical (2.00), the statistically significant difference was attributed to the respondents’ opinions at the level of α ≤ 0.05 between the statistical mean (4.08) and hypotheses mean (3). SD equaled 0.83, not far from zero, indicating the respondents’ results to be consistent and not spread out over a wider range of values.

Most companies use their expertise to identify any risks that may occur and rely on their expertise and knowledge to provide solutions to any possible problems that may occur. Most companies that apply for tender usually capitalize on their prior experience in handling a similar project, which gives them an edge over their competitors that do not have such experience. Their accumulated experience enables them to identify risks and proactively tackle them without hindering the normal workflow of the project. Hence, selecting an experienced construction company to undertake the project is one of the effective ways to avoid the risk before the implementation of the project.

Table 4. Avoiding the risk before implementation of the project.
No. Items Mean Std. Dev RII (%) T Value P Value
Sig.
Rank
Av1 Analyzing based on the expectation quantity for the accuracy time 3.78 0.92 75.60 6.58 0.000 4
Av2 Dependence on experience in work for preparing and planning 4.08 0.83 81.60 10.12 0.000 1
Av3 Prepared schedules and plans can be updated at any time 3.98 0.89 79.60 8.54 0.000 2
Av4 Prepare plans at stand by 3.51 1.06 70.20 3.70 0.000 5
Av5 Invest extra time 3.47 0.98 69.40 3.68 0.001 7
Av6 Distributing the risk and transfer to terminals of the project 3.48 0.98 69.60 3.81 0.000 6
Av7 Use similar projects in implementation to obtain accurate project management information 3.83 0.99 76.60 6.47 0.000 3

 Fig. (3). RII avoid the risk before implementation statements (Av1 to Av7).

The results revealed the “Prepared schedules and plans can be updated at any time” statement (Av3) (RII = 79.60%; P-value = 0.000; T-value = 8.54; SD = 0.89) at the second position. It is very important in the knowledge of construction projects that the plans and engineering tables are subject to any modification and be flexible in the event of any change orders by the owner or consultant so as not to affect the quality of design and operational process. As mentioned earlier, the living conditions in the Gaza strip are unstable, and this is reflected directly in construction projects. Thus, plans of engineering projects must be flexible and be subject to change due to changes in the political and economic conditions. In other words, it is important in construction projects to have a flexible plan and schedules that can be updated, amended or upgraded at any time in the project. Having a rigid plan is risky, especially in areas like the Gaza strip [33]. That is why, this statement has been ranked second.

Ranked at the last position has been “Put the extra time in the time schedules” statement (Av5) (RII = 69.40%; P-value = 0.001; T-value = 3.68; SD = 0.98). There is no doubt that the projects in the Gaza Strip are exposed to risks that affect the supply of materials and equipment to the worksites, and the delay in their supply affects the period for the delivery of the project. Therefore, the construction companies compensate for any potential delay by putting extra time into the plans to avoid any problems in the supply process or any security events that may affect the working days of the construction project. Hence, this may be the reason why this statement has been ranked as the lowest.

### 3.5. Avoiding the Risk during Implementation

This factor involeseight statements that determine the avoidance of risk during the time the project is being implemented, as shown in Table 5.

Table 5. Avoiding the risk during implementation in the construction organizations.
No. Items Mean Std. Dev RII (%) T value P value
Sig.
Rank
AD1 Increase manpower and/or equipment 3.78 0.94 75.60 6.45 0.000 4
AD2 Increase the working hours 3.78 0.89 75.60 6.86 0.000 3
AD3 Change the sequence of work by overlapping 3.82 0.91 76.40 6.94 0.000 2
AD4 Coordinate closely with subcontractors 3.62 0.94 72.40 5.08 0.000 6
AD5 Follow up the implementation to avoid rework 3.88 1.08 77.60 6.36 0.000 1
AD6 Change the tools of implementation 3.40 0.96 68.00 3.23 0.002 8
AD7 Obtain insurance 3.67 1.00 73.40 5.15 0.000 5
AD8 Transfer the risk to a subcontractor 3.60 1.03 72.00 4.52 0.000 7

The findings showed “Follow up the implementation to avoid rework” statement (AD5) (RII =77.60%; P-value =0.000; T-value= 6.36; SD= 1.08) with the highest rank (Fig. 4). Since P-value here equaled 0.000 being less than 0.05 and T statistics = 6.36 > T critical (2.00), the statistically significant difference has been attributed to the respondents’ opinions at the level of α ≤ 0.05 between the statistical mean (3.88) and hypothesis mean (3). SD equaled 1.08, being not far from zero, thereby indicating the respondents’ results to beconsistent and not spread out over a wider range of values.

One of the best ways and means to eliminate any risks or problems is to follow the progress of the work and to comply with the terms of the contract documents and periodically evaluate and address any problems that may occur. This helps directly in identifying risks and predicting them, and finding appropriate solutions for the identified problems. The purpose of following up on the work is to overcome any financial or technical losses that can occur. The major projects stipulate in the contract documents that there should be committees to follow up on the progress of work and supervision. The importance of follow-up during the project implementation through a supervisory engineer is to control and monitor the process of construction project implementation I order to predict possible risks that may occur during the implemen-tation. It is also important to prepare contingency plans that may be used for avoidance of the risks and achievement of the project goals. Continued follow-up of construction projects helps to detect any risks during implementation. Finally, follow-up prevents any problem that may lead to rework, thereby saving effort, time and cost, and preventing any possible dispute between the project parties. Hence, we find this factor as the most important compared to other factors related toavoiding risk during the implementation of the construction project.

The results also revealed that “Change the sequence of work by overlapping” statement (AD3) (RII = 76.40%; P-value = 0.000; T-value = 6.94; SD = 0.91) has been ranked as the second. The executive plan for accomplishing the project activities must be applied to avoid any interference in the activities, which can cause financial risks to the contracting company. This could lead to financial loss in addition to the depletion of human resources, which impacts negatively on the progress of the work and implementation of projects. To get good results and achieve the desired goals, it is best to avoid any overlaps between activities to exclude the possibility of any risks that may occur. Companies often resort to the use of overlaps between activities due to lack of time or change in orders during the implementation phase.

The least ranked statement in this category was the “Change of the tools during implementation” statement (AD6) (RII = 68.00%; P-value = 0.002; T-value = 3.23; SD = 0.96). It is noted that the change of operational tools does not significantly affect the progress (hence the risk) of the project compared to other factors during the implementation. With the existence of a good management team in the workplace and the judicious use of a human resource, any work can be successfully accomplished with the exclusion of risks by appropriate means.

## CONCLUSION

Construction projects are one of the high-risk prone undertakings, especially in areas like the Gaza strip. Due to this reason, this study was carried out to determine the risk management strategies employed by the construction industries in the area. Using a well-designed and adequately tested questionnaire, the objective of the study was successfully achieved, and the following conclusions were drawn:

1. It was found out that among the methods used by the construction organizations for the determination of risk factors, the use of a checklist is the most popular because of its ease of use and effectiveness.

2. For the tools/methods employed for risk analysis by the construction industries, relying on experience in the direct assessment is the most preferred method with an RII value of 78%.

3. When trying to avoid the risk before project implementation, the construction organizations mostly opt for “Dependence on experience in work for preparing and planning” in preference to other methods. Similarly, during the implementation of the project, the construction organizations prefer to “Follow up the implementation in order to avoid rework” as a means of avoiding risk in the project.

As a recommendation, companies should develop alternative contingency plans to face any conditions or obstacles that may occur during the implementation process of the project, thereby facilitating the exclusion of any risks. Similarly, good documentation of the progress of the project, follow-up on the progress of work, thorough documentation, and record of any observations or problems and addressing them before they occur will prove to be helpful in risk management.

## LIMITATION AND FUTURE DIRECTION

The current study aimed at small samples of construction workers in the Gaza Strip and evaluated the scientific methodologies and techniques used by them to detect the risks in construction projects and their ways of managing those risks . Thus, the study recommends that more researches be conducted on other engineering projects, such as electricity, mechanics, and other infrastructure, involving larger sample sizes so thatseveral indicators that reveal risks in engineering projects along with the ways and means to overcome those risks are explored; this will ensure safe and effective implementation of engineering projects.

Not applicable.

### AVAILABILITY OF DATA AND MATERIALS

The data that support the findings of this study are available on request from the corresponding author [B.A.T], upon reasonable request.

None.

### CONFLICT OF INTEREST

Dr. Bassam Tayeh is the Associate Editorial Board Member of The Open Civil Engineering Journal.

Declared none.


text:
Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

I came across this interesting paper entitled Complex Variables Visualized and written by Thomas Ponweiser.

In particular, I was intrigued by the generalized powers of a Möbius transformation (of a matrix, actually), and their actions on the modular tessellation.

So I firstly implemented the generalized powers in my package PlaneGeometry. Then I wrote the script below to visualize the orbit of the modular tessellation under the action of $$R^t$$, $$0 \leqslant t < 3$$, with the notations of the paper. The command fplot(u) generates the modular tessellation under the action of $$R^t$$ when u is the value of $$t$$. Then I use the gifski package to create the animation.

To get the modular transformations $$z \mapsto \frac{az+b}{cz+d}$$, I use the unimodular function of the elliptic package. It generates the quadruples $$(a,b,c,d)$$ of positive integers such that $$ad-bc=1$$. Then we can get all such quadruples $$(a,b,c,d) \in \mathbb{Z}^4$$ by inverting these modular transformations, swapping $$a$$ and $$d$$ and changing their signs.

library(PlaneGeometry)
library(elliptic) # for the 'unimodular' function

# Möbius transformations
T <- Mobius$new(rbind(c(0,-1), c(1,0))) U <- Mobius$new(rbind(c(1,1), c(0,1)))
R <- U$compose(T) # R^t, generalized power Rt <- function(t) R$gpower(t)

# starting circles
I <- Circle$new(c(0,1.5), 0.5) TI <- T$transformCircle(I)

# modified Cayley transformation
Phi <- Mobius$new(rbind(c(1i,1), c(1,1i))) # plotting function #### n <- 8L transfos <- unimodular(n) fplot <- function(u){ opar <- par(mar = c(0,0,0,0), bg = "black") plot(NULL, asp = 1, xlim = c(-1.1,1.1), ylim = c(-1.1,1.1), xlab = NA, ylab = NA, axes = FALSE) draw(unitCircle, col = "black") for(i in 1L:dim(transfos)[3L]){ transfo <- transfos[,,i] # M <- Mobius$new(transfo)
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I), border = "black", col = "magenta") draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI),
border = "black", col = "magenta")
M <- M$inverse() draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I),
border = "black", col = "magenta")
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI), border = "black", col = "magenta") # diag(transfo) <- -diag(transfo) M <- Mobius$new(transfo)
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I), border = "black", col = "magenta") draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI),
border = "black", col = "magenta")
M <- M$inverse() draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I),
border = "black", col = "magenta")
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI), border = "black", col = "magenta") # d <- diag(transfo) if(d[1L] != d[2L]){ diag(transfo) <- rev(d) M <- Mobius$new(transfo)
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I), border = "black", col = "magenta") draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI),
border = "black", col = "magenta")
M <- M$inverse() draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I),
border = "black", col = "magenta")
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI), border = "black", col = "magenta") } } for(i in 1L:dim(transfos)[3L]){ transfo <- transfos[,,i] # M <- Mobius$new(transfo)$compose(T) draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I),
border = "black", col = "magenta")
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI), border = "black", col = "magenta") M <- M$inverse()
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I), border = "black", col = "magenta") draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI),
border = "black", col = "magenta")
#
diag(transfo) <- -diag(transfo)
M <- Mobius$new(transfo)$compose(T)
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I), border = "black", col = "magenta") draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI),
border = "black", col = "magenta")
M <- M$inverse() draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I),
border = "black", col = "magenta")
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI), border = "black", col = "magenta") # d <- diag(transfo) if(d[1L] != d[2L]){ diag(transfo) <- rev(d) M <- Mobius$new(transfo)$compose(T) draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I),
border = "black", col = "magenta")
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI), border = "black", col = "magenta") M <- M$inverse()
draw(M$compose(Rt(u))$compose(Phi)$transformCircle(I), border = "black", col = "magenta") draw(M$compose(Rt(u))$compose(Phi)$transformCircle(TI),
border = "black", col = "magenta")
}
}
}

# animation ####
library(gifski)
u_ <- seq(0, 3, length.out = 181L)[-1L]
save_gif({
for(u in u_){
fplot(u)
}
}, "ModularTessellation.gif", 512, 512, delay = 1/12, res = 144)


text:
# [texhax] \ar

Sun Feb 3 01:34:10 CET 2008

On Tue, Jan 29, 2008 at 06:06:26AM -0800, sarah yasseen wrote:
> "A \ar {->}[r]&B"  gives an arrow that begins at A and ends at B.

Don't know what \ar is, but...

> How to make that arrow starts exactly from A (touches A), i.e., no
> space between A and the arrow?

It's not possible to do this in a generic way, so that it works with
any glyphs, not just A and B, because TeX doesn't know anything about
the actual glyph shapes, it only knows about glyph boxes (which are
rectangular).  So the only way to do this is to insert spacing tweaks,
something like:

A \!\!\! \rightarrow \!\!\!B\cr

\! is a predefined (by plain TeX) negative skip macro for the math
mode.  You should define skip macros for math mode in terms of mu's,
not pt's, like this:

\def\myskip{\mskip-5mu}

HTH,
Oleg


text:
# Simple question about big O

If $f(n)=g(n)$, can we just say that $\mathcal{O}(f(n))=\mathcal{O}(g(n))$? ($f$ and $g$ are two $\log$ functions)

Is it definitely yes? if not please describe why.

-
I am not sure that the equation $\mathcal{O}(f(n))=\mathcal{O}(g(n))$ makes any sense. When you write $f(n)=\mathcal{O}(g(n))$, you mean that $f$ is bounded by $g$, but that's a shorthand notation, not an equality. – Yves Daoust May 7 '14 at 21:06
@YvesDaoust: Treating $\mathcal{O}(f(n))$ as a set, we do have $\mathcal{O}(f(n))=\mathcal{O}(g(n))$ as an equality of sets, though. – user2357112 May 7 '14 at 21:14
Then $f(n)=\mathcal{O}(g(n))$ cannot be written. And what set would $\mathcal{O}(f(n))$ deemed to be ? – Yves Daoust May 7 '14 at 21:17
@YvesDaoust: People who don't like writing $f(n)=\mathcal{O}(g(n))$ often define $\mathcal{O}(g(n))$ as the set of functions $f$ for which there is some constant $k$ such that $f(x)<kg(x)$ for all integers $x$, and write $f(n) \in \mathcal{O}(g(n))$. I always use $\in$ instead of $=$ for Big O notation where typographical restrictions don't require $=$, but I don't know how common that is. A quick search shows the notation used at mathworld.wolfram.com/Big-ONotation.html – user2357112 May 7 '14 at 22:23
@user2357112: Interesting. It confirms that either way the question is ill-formulated. – Yves Daoust May 8 '14 at 6:38

Of course we can. If $f(n)=g(n)$, then $f$ and $g$ are the exact same function, and it doesn't matter whether we use the name $f$ or $g$ to refer to it in any context we choose.
@user3576199: If their bases are not the same, then $f(n) \ne g(n)$. – user2357112 May 7 '14 at 21:01
@user3576199: Then that's an entirely different question from what you asked, and it'd be good to be more careful about that in the future. We still have $\mathcal{O}(f(n)) = \mathcal{O}(g(n))$ from the definition of big-O notation, since it's trivial to find constants for which $af(n)<g(n)$ and $bg(n)<f(n)$. – user2357112 May 7 '14 at 21:06