STRATIFIED CHARGE INTERNAL COMBUSTION ENGINE

Internal combustion engines or popularly known as IC Engines are life line of human society which mostly served as a mobile, portable energy generator and extensively used in the transportation around the world. 

There are many types of IC Engines, but among them two types known as petrol or SI engines and diesel or CI engines are well established. Most of the automotive vehicles run on either of the engines. Despite their wide popularity and extensive uses, they are not fault free. 

Both SI Engines and CI Engines have their own demerits and limitations. 


Limitations of SI Engines (Petrol Engines) 

Although petrol engines have very good full load power characteristics, but they show very poor performances when run on part load. 

Petrol engines have high degree of air utilisation and high speed and flexibility but they can not be used for high compression ratio due to knocking and detonation. 

Limitations of CI or Diesel Engines: 

On the other hand, Diesel engines show very good part load characteristics but very poor air utilisation, and produces unburnt particulate matters in their exhaust. They also show low smoke limited power and higher weight to power ratio. 

The use of very high compression ratio for better starting and good combustion a wide range of engine operation is one of the most important compulsion in diesel engines. High compression ratio creates additional problems of high maintenance cost and high losses in diesel engine operation. 

For an automotive engine both part load efficiency and power at full load are very important issues as 90% of their operating cycle, the engines work under part load conditions and maximum power output at full load controls the speed, acceleration and other vital characteristics of the vehicle performance. 

Both the Petrol and Diesel engines fail to meet the both of the requirements as petrol engines show good efficiency at full load but very poor at part load conditions, where as diesel engines show remarkable performance at part load but fail to achieve good efficiency at full load conditions. 

Therefore, there is a need to develop an engine which can combines the advantages of both petrol and diesel engines and at the same time avoids their disadvantages as far as possible. 

Working Procedures: 

Stratified charged engine is an attempt in this direction. It is an engine which is at mid way between the homogeneous charge SI engines and heterogeneous charge CI engines. 

Charge Stratification means providing different fuel-air mixture strengths at various places inside the combustion chamber. 

It provides a relatively rich mixture at and in the vicinity of spark plug, where as a leaner mixture in the rest of the combustion chamber. 

Hence, we can say that fuel-air mixture in a stratified charge engine is distributed in layers or stratas of different mixture strengths across the combustion chamber and burns overall a leaner fuel-air mixture although it provides a rich fuel-air mixture at and around spark plug. 

THE IMPORTANCE OF MANUFACTURING ENGINEERING

If we carefully think about human civilization, one shall notice an wonderful fact about human beings. The thing that made us different from other hominids is the skill to manufacture tools. We just triumphed due to our ability to make primitive tools out of stone and metals during the dawn of the civilizations. Since then much time has passed and we have entered into a Machine Era and man has been still continuously engaged in converting the natural resources into useful products by adding value to them through machining and other engineering activities applying on the raw materials. Manufacturing is the sub branch of Engineering which involves the conversion of raw materials into finished products.

The conversion of natural resources into raw materials is normally taken care of by two sub branches of engineering viz. Mining and Metallurgy Engineering. The value addition to the raw materials by shaping and transforming it to final products generally involves several distinct processes like castings, forming, forging, machining, joining, assembling and finishing to obtain a completely finished product.

Understanding Manufacturing Engineering largely based upon three engineering activities and they are Designing,  Production and Development of new more efficient techniques.

At the Design stage, engineering design mainly concentrates on the optimization of engineering activities to achieve most economical way to manufacture a goods from raw materials. It also chooses the raw materials and impart the requisite engineering properties of materials like hardness, strength, elasticity, toughness by applying various heat treatment to them.

During the production stages, the selection of the important process parameters to minimize the idle time and cost, and maximizing the production and its quality is very important.

The New Technologies must be implemented to adapt to the changing scenarios of the markets and demands to make the sales competitive and sustainable.

ELEMENTS OF C PROGRAMMING

Q) Write a C programme to check a odd or even number

A) c program to check odd or even:

We will determine whether a number is odd or even by using different methods all are provided with a code in c language. As you have study in mathematics that in decimal number system even numbers are divisible by 2 while odd are not so we may use modulus operator(%) which returns remainder, For example 4%3 gives 1 ( remainder when four is divided by three). Even numbers are of the form 2*p and odd are of the form (2*p+1) where p is is an integer. C program to check odd or even using modulus operator

#include<stdio.h>
main()
{
int n;
printf("Enter an integer\n");
scanf("%d",&n);
if ( n%2 == 0 )
printf("Even\n");
else
printf("Odd\n");
return 0;
}

We can use bitwise AND (&) operator to check
odd or even, as an example consider binary of 7
(0111) when we perform 7 & 1 the result will be
one and you may observe that the least
significant bit of every odd number is 1, so
( odd_number & 1 ) will be one always and also
( even_number & 1 ) is zero.
C program to check odd or even using bitwise
operator

#include<stdio.h>
main()
{
int n;
printf("Enter an integer\n");
scanf("%d",&n);
if ( n & 1 == 1 )
printf("Odd\n");
else
printf("Even\n");
return 0;
}

Find odd or even using conditional operator

#include<stdio.h>
main()
{
int n;
printf("Input an integer\n");
scanf("%d",&n);
n%2 == 0 ? printf("Even\n") : printf("Odd\n");
return 0;
}

C program to check odd or even without using
bitwise or modulus operator

#include<stdio.h>
main()
{
int n;
printf("Enter an integer\n");
scanf("%d",&n);
if ( (n/2)*2 == n )
printf("Even\n");
else
printf("Odd\n");
return 0;
}

In c programming language when we divide two
integers we get an integer result, For example
the result of 7/3 will be 2.So we can take
advantage of this and may use it to find whether
the number is odd or even. Consider an integer
n we can first divide by 2 and then multiply it by
2 if the result is the original number then the
number is even otherwise the number is odd.
For example 11/2 = 5, 5*2 = 10 ( which is not
equal to eleven), now consider 12/2 = 6 and 6 *2
= 12 ( same as original number). These are some
logic which may help you in finding if a number
is odd or not.

Q) Write a C program to check whether input
alphabet is a vowel or not.

A) This code checks whether an input alphabet
is a vowel or not. Both lower-case and upper-
case are checked.

#include <stdio.h>
int main()
{
char ch;
printf("Enter a character\n");
scanf("%c", &ch);
if (ch == 'a' || ch == 'A' || ch == 'e' || ch == 'E' ||
ch == 'i' || ch == 'I' || ch =='o' || ch=='O' || ch ==
'u' || ch == 'U')
printf("%c is a vowel.\n", ch);
else
printf("%c is not a vowel.\n", ch);
return 0;
}

Check vowel using switch statement

#include <stdio.h>
int main()
{
char ch;
printf("Input a character\n");
scanf("%c", &ch);
switch(ch)
{
case 'a':
case 'A':
case 'e':
case 'E':
case 'i':
case 'I':
case 'o':
case 'O':
case 'u':
case 'U':
printf("%c is a vowel.\n", ch);
break;
default:
printf("%c is not a vowel.\n", ch);
}
return 0;
}
Function to check vowel
int check_vowel(char a)
{
if (a >= 'A' && a <= 'Z')
a = a + 'a' - 'A'; /* Converting to lower case or
use a = a + 32 */
if (a == 'a' || a == 'e' || a == 'i' || a == 'o' || a == 'u')
return 1;
return 0;
}
This function can also be used to check if a
character is a consonant or not, if it's not a
vowel then it will be a consonant, but make sure
that the character is an alphabet not a special
character.
Q) Write C program to perform addition,
subtraction, multiplication and division.
A) C program to perform basic arithmetic
operations which are addition, subtraction,
multiplication and division of two numbers.
Numbers are assumed to be integers and will be
entered by the user.
#include <stdio.h>
int main()
{
int first, second, add, subtract, multiply;
float divide;
printf("Enter two integers\n");
scanf("%d%d", &first, &second);
add = first + second;
subtract = first - second;
multiply = first * second;
divide = first / (float)second; //typecasting
printf("Sum = %d\n",add);
printf("Difference = %d\n",subtract);
printf("Multiplication = %d\n",multiply);
printf("Division = %.2f\n",divide);
return 0;
}
In c language when we divide two integers we
get integer result for example 5/2 evaluates to 2.
As a general rule integer/integer = integer and
float/integer = float or integer/float = float. So
we convert denominator to float in our program,
you may also write float in numerator. This
explicit conversion is known as typecasting.
Q) Write a C programme to check a Leap year.
A) C program to check leap year: c code to
check leap year, year will be entered by the
user.
#include <stdio.h>
int main()
{
int year;
printf("Enter a year to check if it is a leap year
\n");
scanf("%d", &year);
if ( year%400 == 0)
printf("%d is a leap year.\n", year);
else if ( year%100 == 0)
printf("%d is not a leap year.\n", year);
else if ( year%4 == 0 )
printf("%d is a leap year.\n", year);
else
printf("%d is not a leap year.\n", year);
return 0;
}

সময় কি এবং সময়ের অস্তিত্বের কারণ কি ?

এক সময় পদার্থ বিদ্যায় সময় কে আমাদের মস্তিস্কর উপজ বলে চিহ্নিত করা হত । তখনকার দিনে  বলা হতো সময় ঠিক করে বলতে গেলে এমন একটা জিনিস যা একসঙ্গে  সবকিছুকে ঘটতে দেয়না । এমন কি  আলবার্ট আইনস্টাইন বলেছিলেন  যে এই জগতে অতীত  এবং ভবিষ্যত এক মরিচিকা  ছাড়া আর কিছুই নয়, মানুষের ভ্রম মাত্র । কিন্তু  সত্যি করে বলতে গেলে  সময় কি আর কেন আমরা সময় কে উপলব্ধি করতে পারি তার কোনো সঠিক ব্যাখ্যা  নেই ।



তবে সম্প্রতি পদার্থ বিজ্ঞানীরা এটা বের করার চেষ্টা করছেন যে সত্যি সত্যি  বলতে গেলে কেন এই বিশাল বিশ্ব ব্রহ্মান্ড সময়ের উপর নির্ভরশীল । কেন আমরা সময়ের গতিকে পরিচালিত করতে পারিনা, কেন এই বিশ্ব ব্রহ্মান্ড সুচারু রূপে  চলতে গেলে সময়ের উপর নির্ভরশীল হয়ে পরে ? কেও কেও আবার বলছেন সময় বলে কিছু নেই যা অবিরত চলতে থাকে , বরঞ্চ এটা  বলা যেতে পারে কি সময় অনেকটা বালুকা দানার মতন । আবার কিছু মানুষ আছেন যারা বলে চলেছেন যে সময়ের একটি নয় বরঞ্চ দুটি দিক আছে ।

Once upon a time, physicists liked to dismiss those who dwelled too much on the passing of the seconds, days and years. They wrote off the apparent flow of time as a trick of the mind. They joked that time is what keeps everything from happening at once. Albert Einstein, who believed the distinction between the past and future is an illusion, declared that time is “what you measure with a clock”.

In recent years, however, physicists have been working around the clock to find out what makes the cosmos tick. Some suggest that there is not a continuous flow of time, but rather spacetime moments trickling like grains of sand through an hourglass. Others say that there should be two dimensions of time, not one (so called “hypertime” jettisons the pesky headache of time travel, which is allowed by current theory); or that time, not being fundamental, was born in the Big Bang and could grind to a halt in a few billion years; or, according to the British philosopher Julian Barbour, time does not exist because we dwell within a heap of moments, each an instant of frozen time.

Quite a few feel that an overhaul of what we mean by “time” could lead to the next great leap in physics. Among them is Lee Smolin, of the Perimeter Institute for Theoretical Physics in Canada. Smolin argues that science is blighted by what he says are unreal and inessential conceptions of time. He insists that “time is real” and that its reformulation could be central to finding the long-sought after “theory of everything”.

In Time Reborn, he offers an entertaining, head-spinning and, yes, timely blend of philosophy, science, and speculation to put the Now back into physics.

The problem with time dates back centuries. The physical laws outlined by greatest figure of the Scientific Revolution, Isaac Newton, are indifferent to the direction of time and suggest the future is determined by the past. Thus, as the French mathematician Pierre-Simon Laplacefamously pointed out, we may regard the present state of the universe as the effect of its past and the cause of its future. And if our future’s already written, then the things that are most valuable about being human are illusions, along with time itself.

Ever since Newton, physicists have been developing ever more exact laws describing the behaviours of the world. These laws don’t change. They are more real than time. They are timeless truths. “If laws are outside of time, then they’re inexplicable,” says Smolin. “If we want to understand law then law must evolve, law must change, law must be subject to time. Law then emerges from time and is subject to time rather than the reverse.”

He cites heavyweights such as the Briton Paul Dirac and the American philosopher Charles Sanders Peirce who have also suggested that the laws of physics evolve. In an earlier book, Smolin outlined one somewhat hairy scheme to explain how this may occur: universes reproduce inside black holes and, as in Darwin’s natural selection, those with parameters for spawning new black holes have offspring; those that do not fizzle out. The laws become fine-tuned, changes accumulating each time a baby cosmos is born. This daisy chain of descendant universes unfolds in time, and Smolin believes that this is real time.

Guided by an insight from Newton's great rival, Gottfried Leibnitz, Smolin’s picture of the cosmos violates Einstein's relativity because it requires an absolute time, preferred global time. To make time real, he also puts forward a weird idea, “the principle of precedence”, that repeated measurements of a certain phenomenon yield the same outcomes not because it obeys a law of nature but simply because the phenomenon is a habit. This would allow new measurements to yield new outcomes, not predictable from knowledge of the past.Thus the future becomes open once more.

A few years ago, Smolin triggered much heated debate with The Trouble with Physics in which he argued that attempts to explain the fundamentals of the universe by the dominant paradigm of so-called string theory, which comes in many flavours, remain untested “because they make no clean predictions or because the predictions they do make are not testable”. The problem is that the ideas in Time Reborn feel just as wildly speculative, if not more so.

Still, his maverick meditations serve as a reminder that it’s hard to find a consensus on the future of physics at an exciting time when it feels like everything could be altered in an eye-blink by the findings from extraordinary experiments under way to probe the puzzles of dark matter, dark energy, antimatter and more. That is the physicists’ ultimate arrow of time, pointing from today’s understanding towards the next great mystery.

MOCK EXAM PAPER FOR PRACTICE; EME-101; ENGINEERING MECHANICS

Printed Pages:4                                    Paper Code: EME-101                                                     

 

B.  Tech –1^st Year (SEM.I)

Pre University Examination, May2012 – 13

Engg.Mechanics

Time:   3hrs                                                                 Total Marks:  100                                        

Note:   (1)        Attempt all questions.

(2)        Be precise in your answer.

Section-A

Tick the appropriate answer:

1. Three forces P, 2P and 3P are exerted along the directions of three sides of equilateral triangle. Their Resultant is 

  a) √3P               b) 3√3P               c) 3P                d) none of the above

2. If two forces P and Q act at an angle Ө, the resultant of these two forces would make an angle α with P such that  

 a) tan α = Q Sin Ө  /  P-Q Sin Ө         b) tan α = P Sin Ө  / P+ Q Sin Ө       

 c) tan α = Q Sin Ө / P+ Q Cos Ө        d) tan α= P Sin Ө / Q - P Cos Ө  

3. The center of gravity of a semicircle  of radius r made of metal is 

 a) on the base                           b) on the perimeter             

 c) 3r/8 above the base              d) 4r/3π above the base.

4. The parallel axis theorem for moment of inertia is

 a) I_zz = I_xx + I_yy                           b) I_Gx= I_xx + AY²             

 c) I_Gx= I_xx - AY²                         d)   I_Gx= I_xx + AX²                 

Fill in the blanks:

5. A body is on the point of sliding down an inclined plane under its own weight. If the inclination of the plane to the horizontal is 30° degree the angle of friction will be----------------------.

6. The velocity of a particle falling from a height h just  before touching ground is ---------------

7. A beam is having more than two supports is called---------------------- beam and such beams are statically   -----------------.

8. A car moving with uniform acceleration covers 450m in a 5 seconds and covers 700m in the next 5 seconds interval. The acceleration of the car is……………. .m /s^2.

9. Varignon’s theorem is related to……………

10. A truss is said to be rigid in nature when there is no --------------- on application of any external --------------------.             (2x 10=20)

Section-B

Attempt any two parts from each question.           (3x10 = 30)

 Q.1. (a) Define parallelogram law of forces and lami’s theorem.

(b) Find the resultant of the force system given in figure-2, Also find its position:

 (c) A uniform ladder weighting 200 N and length 6m is placed against a vertical wall in a position where its inclination to the vertical is 30 degree. A man weighting 600N climbs the ladder. At what position will he induce slipping? Take coefficient of friction μ = 0.2 at both the contact surfaces of ladder.

Q.2(a) How are the trusses classified? What are the assumptions taken while analyzing a plane truss?

 (b) Draw the reactions for the beam AB loaded through the attached strut.

 (c) Find the reaction in the cantilever beam shown in figure:

Q.3. (a) Define Parallel axis theorem and Perpendicular axis theorem.

(b) Find the Moment of Inertia of the I section shown in figure-5 about x-x and y-y axes.

(c) Derive an expression for mass moment of inertia of a right circular cone of base  radius R, height H and mass M about its axis.   

Section-C

 (5x10=50)   

Q.1. (a) Define impulse. State and explain the D'Alemberts principle.

(b) The equation of motion of a particle moving in a straight line is given by  the equation s =16t +4t²-3t³ where s is the total distance covered from the starting  point in meter at the end of t seconds. Find

(i) Displacement, velocity and acceleration 2 seconds after the start

(ii) the displacement and acceleration when velocity is zero

(iii) the maximum velocity of the particle.

(c) Define the following terms:    i) inertial force (ii) angle of repose (iii) coplanar non concurrent force system (iv) angular momentum 

 

Q.2(a) A car moving with an constant acceleration from rest in the first 50 sec, then in the next 40 second it moves with a constant velocity, in the next 20 second it comes to rest. Find the maximum and average velocity and the acceleration of the car:

(b)