By:
R.Ananthakrishnan
3rd year 
Energy 

Aerodynamics plays a prominent role in the flight of a cricket ball released by a bowler. The main interest is in the fact that the ball can follow a curved flight path that is not always under the control of the bowler.

INTRODUCTION
On each delivery, the ball can have a different trajectory, varied by changing the pace, the length, the line or, most subtly of all, by moving or "swinging" the ball through the air so that it drifts sideways.

A cricket hall has six rows of preeminent stitching along its equator, with typically 60-80 stitches m each row. Which makes up the "primary"   seam. The better quality cricket  balls used are in fact made out of four pieces of leather, so that each hemisphere has a line of internal stitching forming the "'quarter" or "secondary" seam. The two quarter seams are traditionally set at right angles to each other. These primary and quarter seams play a critical role in the aerodynamics of a swinging cricket ball.
                                                                                                                         
AERODYNAMICS   OF   CONVENTIONAL  SWING
Suppose you suspend two balls a few centimeters apart and blow between them. Because the air between them is disturbed and the air outside is stable and has a greater pressure, the balls will come together.
Fast bowlers in cricket make the ball swing by a judicious use of the primary seam. The ball is released with the seam at an angle to the initial line of flight. Over a certain Reynolds number range, the seam trips the laminar boundary layer into turbulence on one side of the ball whereas that on the other (non seam) side remains laminar  (Fig. 1).
[The Reynolds number is defined as, Re = Ud/v, where U is the ball  velocity, d is its diameter, and v is the air kinematic viscosity.]
By virtue of its increased energy, the turbulent boundary layer, separates later (further back along the ball surface) compared to the laminar layer and so a pressure differential, which results in a side force, is generated on the ball .

In order to show that such an asymmetric boundary layer separation can indeed occur on a cricket ball, a ball was mounted in a wind tunnel and smoke was injected into the separated region behind the bail, where it was entrained right up to the separation points (Fig. 2). The seam has tripped the boundary layer on the lower surface into turbulence, evidenced by the chaotic nature of the smoke edge just downstream of the separation point. On the upper surface, a smooth, clean edge confirms that the separating boundary layer was in a laminar state. Note how the laminar boundary layer on the upper surface has separated relatively early compared to the turbulent layer on the lower surface. The asymmetric separation of the boundary layers is further confirmed by the upward deflected wake, which implies that a downward force is acting on the ball.


When a cricket ball is bowled, with a round arm action as the laws insist, there will always be some backspin imparted to it. In simple terms, the ball rolls-off the fingers as it is released. In scientific terms, the spin is necessarily imparted to conserve angular momentum. The ball is usually held along the seam so that the
backspin is also imparted along the seam (the ball spins about an axis perpendicular to the seam plane). At least this is what should be attempted, since a "wobbling" seam will not be very efficient at producing the necessary asymmetric orientation, and hence separation. This type of release is obviously not very easy to master and it is the main reason why not every bowler can swing even a brand new cricket ball effectively.
The  maximum side force is obtained at a bowling speed of about 30 m/s (67 mph) with the seam angled at 20 ° and the ball spinning backwards at a rate of 11.4 revs/s. At a seam angle of 20 °, the Re based on trip (seam) height is about right for effective tripping of the laminar boundary layer. At lower speeds, a bowler should select a larger seam angle so that by the time the flow accelerates around to the seam, the critical speed for efficient tripping has been reached. 


 Of course, releasing a ball spinning along the seam (without much wobble) becomes more difficult as the seam angle is increased. Spin on the ball helps to stabilize the seam orientation. Basically, for stability, the angular
momentum associated with the spin should be greater than that caused by the torque about the vertical axis due to the flow asymmetry. Too much spin is of course also detrimental, since the effect of the ball’s surface roughness is increased and the critical Re is reached sooner.


AERODYNAMICS   OF  REVERSE  SWING
As discussed above, for conventional swing it is essential to have a smooth polished surface on the non seam side facing the batsman so that a laminar boundary layer is maintained. At the critical Re, the laminar boundary layer on the non seam side undergo transition and the flow symmetry, and hence side force, starts to decrease. A further increase in Re results in the transition point moving upstream, towards the front of the ball. A zero side force is obtained when the flow field on the two sides of the ball becomes completely symmetric. In terms of reverse swing, the really interesting flow events start to occur when the Reynolds number is increased beyond that for  zero side force. Amongst other factors, transition is strongly dependent on the condition (or roughness) of the ball’s surface. Of course, the negative sideways deflection will not be  as much as the positive deflection since the ball spends less time in the air at the higher velocity. So it seems as though
reverse swing can be obtained at realistic , but relatively high bowling velocities. In particular, reverse swing can be clearly obtained even on a new ball, without any tampering of the surface. Some of the fastest bowlers, such as Jeff Thomson (Australia) and Shaun Tait in present times have been measured bowling in the 90+ mph range and so reverse swing would certainly be achievable by them. Alas, not every bowler can bowl at 90 mph, so what about the mere mortals who would still like to employ this new art? The "old" ball, with an estimated use of about 60 overs, gives less positive  side force compared to the new balls, but it also produces reverse swing at a lower velocity of about 65-75 mph.
The critical Reynolds number on the used ball is lower because of the
rougher surface. The key to reverse swing is early transition of the boundary layers on
the ball's surface and the exact velocity beyond which reverse swing is obtained in
practice will decrease with increasing roughness.


SWINGING AN OLD BALL
There is another distinct advantage in maintaining a sharp contrast in surface roughness on the two sides or hemispheres of the ball. The primary seam plays a crucial role in both types of swing. It trips the laminar boundary layer into a turbulent state for conventional swing and thickens the turbulent boundary layer for reverse swing. During the course of play, the primary seam becomes worn and less pronounced and not much can be done about it unless illegal procedures are invoked to restore it, as discussed above. However, a hall with a worn seam can still be swung, as long as there is a sharp contrast in surface roughness between the two sides. In this case, the difference in roughness, rather than the seam, can be used to produce the asymmetric flow. The seam is oriented lacing the batsman (straight down the pitch) at zero degrees incidence. The critical Re is lower for the rough side and so, in a certain Re range, the boundary layer on the rough side will become turbulent, while that on the smooth side remains laminar. The laminar boundary layer separates early compared to the turbulent boundary layer, in the same way as for conventional swing, and an asymmetric flow, and hence side force, is produced. The ball in this case will swing towards the rough side. At very high bowling speeds, the boundary layers on both surfaces will be turbulent and the ball will swing towards the smooth side, much like in the case of reverse swing. 


EFFECTS OF METEOROLOGICAL CONDITIONS
 When the ground is soft with green wet grass, the new ball will retain its shine for a longer time, thus helping to maintain a laminar boundary layer on the non-seam side. However, the real question is whether a given
ball will swing more on a damp or humid day. The only property of air that may conceivably be influenced by a change in meteorological conditions is the Re through a change in the air viscosity or density. However, Bentley et al. (1982) showed that the average changes in temperature and pressure encountered in a whole day would not change the air density and viscosity, and hence Re. by more than about 2%. Incidentally, although humid or damp air is often referred to as constituting a "heavy" atmosphere by cricket commentators, humid air is in fact less dense than dry air. There is no (positive) scientific evidence which supports the view that humid conditions are more conducive to swing. There is a possibility that the amount of spin imparted to the ball may be affected. It was although found that the varnish painted on all new balls reacts with moisture to produce a somewhat tacky surface.The tacky surface would ensure a better  grip and thus result in more spin as the ball rolls-off the fingers.

MYTHS AND MISCONCEPTIONS
The notion that this makes the ball heavier on this side and the ball would therefore swing in that direction has no aerodynamic basis to it whatsoever.

CONCLUSIONS
While it is generally believed (with some justification) that tampering with the ball's surface helps in achieving reverse swing, the exact form of the advantage is still not generally understood. It is shown here that the critical bowling speed at which reverse swing can be achieved is lowered as the ball's surface roughness increases. Perhaps the biggest misconception is that one must tamper with the ball to achieve reverse swing and this is certainly not the case. Reverse swing can be obtained with a brand new (red) tour-piece ball, but only at bowling speeds of more than 90 mph. It is now known how late swing is actually built into the flight path of a swinging cricket ball and it is this, rather than some special phenomenon, that is often observed on the cricket field.
The introduction of the new white ball with its unique outer cover finish has started a new controversy on how its swing properties differ from those of a conventional red ball. Needless to say, cricket ball aerodynamics would not be such a fascinating subject if all the mysteries and
controversies could be readily answered and settled.

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Satya Sravan
2nd year
 Electronics & Communication Engg.

Hope many of us use a touchscreen mobile or a gadget with touch screen interface. Did you ever think what the technology behind touchscreen is? Let’s know what a touchscreen is, how it works and about the technology behind its operation.

A touchscreen is an electronic visual display that can detect the presence and location of a touch within the display area.The touch screen is one of the easiest to use and most intuitive of all computer interfaces. The touchscreen interface is being used in a wide variety of applications to improve human-computer interaction.

HOW IT WORKS ?
Basically, there are three components used in touch screen technology.

  •   Touch sensor, a panel with a touch responsive surface.

  •  Controller, the hardware that converts the voltage changes on the sensor into signals the computer or other device can receive.
  • Software, tells the electronic devices what's happening on the sensor and the information coming from the controller.
TOUCH SENSORS
Systems are built based on different types of sensors: resistive (most common), surface acoustic wave, and capacitive (most smart phones).

RESISTIVE TOUCHSCREEN TECHNOLOGY
The resistive system is comprised of five components, including the CRT (cathode ray tube) or screen base, the glass panel, the resistive coating, a separator dot, a conductive cover sheet and a durable top coating.
The two metallic layers become connected when a finger or stylus presses down on the top surface. The surface acts as a pair of voltage dividers with connected outputs. This causes a change in the electrical current. The pressure from your finger causes conductive and resistive layers of circuitry to touch each other, changing the circuits' resistance, which registers as a touch screen event that is sent to the computer controller for processing.
HOW IT LOOKS


WORKING


OPERATION




CAPACITIVE TOUCHSCREEN TECHNOLOGY

The touch pad contains a two-layer grid of electrodes that are connected to a sophisticated full-custom mixed signal integrated circuit (IC) mounted on the reverse side of the pad. The upper layer contains vertical electrode strips while the lower layer is composed of horizontal electrode strips.

A human finger near the intersection of two electrodes modifies the mutual capacitance between them, since a finger has very different dielectric properties than air. When a user touches the screen, some of the charge is transferred to the user, and makes the potential difference on the screen. After the panel controller recognizes that, the controller will send the X-Y axis information to the PC port.

Capacitive technology includes technology based on the surface capacitance, projected capacitance, mutual and self-capacitance.

The advantage is that capacitive technology transmits almost 90% percent of the light from the screen.
HOW IT LOOKS


 WORKING

OPERATION




SURFACE ACOUSTIC WAVE (SAW) TECHNOLOGY

It is one of the most advanced touch screen types.The technology is based on two transducers (transmitting and receiving) placed for the both of X and Y axis on the touch panel. The other important element of SAW is placed on the glass, called reflector.

The controller sends electrical signal to the transmitting transducer, and transducer converts the signal into ultrasonic waves and emits to reflectors that are lined up along the edge of the panel. After reflectors refract waves to the receiving transducers, the receiving transducer converts the waves into an electrical signal and sends back to the controller. When a finger touches the screen, the waves are absorbed, causing a touch event to be detected at that point.

WORKING

OPERATION





INFRARED TOUCHSCREEN TECHNOLOGY

The Infrared Touch Screen is a frame which is integrated with a printed circuit board that contains a line of IR-LEDs and photo transistors hidden behind the bezel of the touch frame. Each IR-LEDs and phone transistors are hidden behind the invisible infrared light. The bezel covers the parts from the operation environment while allowing the IR beams to pass through.



The controller sequentially pulses LEDs to create a grid of IR light beams. When a user touches, the screen enters the grid by a stylus which can interrupt the IR light beams. The photo transistors from X and Y axes coordinates to the host.

Other technologies include optical imaging, dispersive signal technology, strain-gauge touch screen technology and acoustic pulse recognition. 



COMPARISON TABLE


RESISTIVE
CAPACITIVE
SAW
INFRARED
Accuracy
2% of screen dimension
1% of screen dimension
1% of screen dimension
1% of screen dimension
Resolution

 16K x 16K
10K x 10K (approx.)
384x16
Light transmission
<= 82% overall
<= 88% @ 550nm
<= 92% overall
92%, Up to 100%
Operating temperature
-20C to +50C
-15C to +70C
-20C to +50C
-20C to +85C
Operation          
Finger or stylus
Finger only
Finger or soft-tipped stylus     
Finger or stylus
Positive talk
More accurate and durable, low cost
Repeatability, no moving parts, protective overcoat
Good response, reliability, easy to maintain
High resolution, clarity, durability, safety.
Negative talk
Optics are not much better, easily vandalized
Less transmission, expensive, affected by EMIR
Hard to integrate, affected by humidity & dirt
Highly sensitive



CONCLUSION

The touchscreen technology is used in ATMs, Self-Checkout Counters, Airport Check-in, PDAs, Tablet PCs, Mobile Phones, Handheld Gaming Consoles, Multi-Touch Collaboration Wall, image processing and image capture etc.

Touch screen technology will increase in significance as an I/O technique for user oriented embedded systems. The steady improvement in the use of touch sensors punctuated by innovation will continue to broaden the range of applications that touch screens can serve.





 

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Shikha Jodhani 
Third Year
Civil







With more attention than ever being focused on energy conservation, vehicle fuel efficiency, and new alternatives such as hybrid cars and bio-based fuels, the significance of road construction materials on energy usage is often overlooked.
The fact is, that concrete pavements give vehicles greater fuel
efficiency, and saves energy. As a result, fuel costs and CO2
emissions are reduced.
Another factor is energy needed for construction. Because concrete pavements are produced with locally sourced and abundant raw materials, less fuel is required to transport the raw
materials and produce concrete. Asphalt pavements include petroleum, which is most-often
imported from various regions around the world.
Driving vehicles on concrete roadways provide better fuel mileage because there’s not as much deflection or ‘rolling resistance’ as with asphalt pavements.
A deflected pavement absorbs energy that otherwise would be used to propel the vehicle forward.



Research Facts:
In the project ‘Pradhan Mantri Gram Sadak Yojna’ the   pavement  was   evaluated   by   Falling  weight Deflectometer using a dynamic load of 45kN on 300mm diameter plate. The equivalent elastic modulus of the 100mm compacted flexible concrete was about 4500 MPa, three times the modulus of high strength bituminous concrete used in major highways. Its expected life is 15 to 20 years. The cost of 250m long pavement with a hard shoulder
of laterite boulder was found to be Rs.4.00 lakhs and the cost
per kilometer is estimated as Rs16.00 lakhs .



Just one glance at Mumbai’s landmark Marine Drive will amply demonstrate the durability and resilience of concrete roads. Even after seven decades of its construction, this seafront arterial road shows few signs of distress as compared to much newer stretches built in recent years.
REDUCING U.S. DEPENDENCE ON FUEL




CONSTRUCTING CONCRETE PAVEMENTS:

Concrete roads have a life cycle of 50 years and also help save 15% in fuel consumption. A combination of fly-ash based concrete roads is environment-friendly and has a 50% longer life cycle.
Concrete roads are typically built in a continuous, single-layer method called slipform paving. The result is a very efficient operation requiring a comparatively low amount of fossil fuel for construction vehicles. Asphalt pavements require a large amount of energy to heat materials up to 325°F at the production plant and are placed in multiple layers (often 3 or more for highways).
For a 10" thick pavement, an asphalt roadway would require about 5½ times more diesel fuel to construct than a concrete road.
> It takes 2.90 gallons of diesel fuel per ton of asphalt road.
> It takes just 0.50 gallons of diesel fuel per ton of concrete road.

Tips to save fuel..

ü While going on a long drive try to keep the windows close since open windows increases resistance to wind flow that increases fuel consumption by as much as 20%. This logically means that if one spends Rs200 a week on petrol, he can save Rs40 a week, which sum up to Rs160 a month. This may seem silly to some who feel they don’t require to do saving but one must know that same money piles up to big amount in long terms and will pay off during their rainy days.

ü More and more car drivers have changed their priorities and now want all to save fuel. Start-stop systems have therefore become standard features in modern automobiles. When the vehicle comes to a standstill, the engine is automatically shut down and started up again when the driver depresses the clutch before moving off. It’s an approach that certainly saves fuel, but the technology does its drawbacks. As the starter motor draws off considerable current from the system, the on-board voltage level can fall from its normal level of 12 volts to as low as 6 volts. Which means the radio and ventilation will switch off, and the lights will dim.To prevent such complications during starting, a DC/DC converter was the solution. It aims to boost up the voltage to a stable 12 volts. Its design is very compact and can be easily integrated into the vehicle. This is one of the innovations between battery and energy management.A start-stop system significantly increases the number of times the engine is started, it is essential to protect the starter battery against overload. Therefore, another innovation comes to place which is called the intelligent battery sensor which provides an additional check. The sensor monitors battery status and transmits the information to the cars body controller, which only enables the start-stop functions if the three key battery parameters; capacity, performance and age are in the required range.
DC/DC converter and IBS therefore make the ideal combination for saving fuel. The converter adds comfort and convenience, while the intelligent battery sensor protects the battery and ensures that the vehicle has no problem starting.




ü Make sure your tires are properly inflated .This prevents increased rolling resistance. Under-inflated tires can cause fuel consumption to increase by as much as 6%. Check tire pressure at least once a month, when the tires are 'cold' (i.e. when the vehicle has not been driven for at least three hours or for more than 2km). Start by checking tire pressures in your driveway. Note any tire that is underinflated, and then drive to the nearest gas station to add air. Check tire pressures again at the station, and inflate the low tires to the same level as the others (these will likely have higher pressure than they did in the driveway, since the tires have heated up.) 


Radial tires can be under inflated yet still look normal. Always use your own tire gauge for consistent results. On average, tires lose about 1 psi per month and 1 psi for every 10 degree drop in temperature.


To determine the correct tire inflation for your car, consult the car's operator manual or ask your tire dealer. Do not inflate your tires to the 'maximum allowed' pressure which is marked on the side of your tires.


According to the Energy Information Administration, tire efficiency could save approximately 800,000 barrels of oil a day


ü Tighten your gas cap  - If you don't tighten up the gas cap to the second click, gas can evaporate. According to the Car Care Council (carcare.org), loose, missing or damaged gas caps cause 147 million gallons of gas to evaporate every year. Think "aerodynamic" and "lightweight". Reduce drag. Out on the open highway, keep windows rolled up to reduce drag. Remove bicycle and ski racks when not in use. Excess weight also uses more fuel. Remove unnecessary items from inside the vehicle, trunk or truck bed. An extra 100lbs (48 kg) of weight can increase your fuel bill by 2%. 




ü The 30-second Warm Up

§  Do not let your engine idle for more than 30 seconds after its initial start. Engines warm up faster when they are in motion.
§  Idling for more than 30 seconds not only wastes fuel but also harms your engine, since the amount of lubricating oil being pumped to the engine’s various parts is the minimum when the engine is in neutral and idling.
§  Depress the accelerator just once when needed, as unnecessary pumping wastes fuel.





           

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Akash Bohare & Rishika Gaud 
Second Year
Chemical
                                                              
How 3D works..

The first of the 3d movies made its debut in 1922 using the oldest form of technology - anaglyph images - to produce stereoscopy. To understand this we need to consider how the eyes work to see in real life. Assuming no vision issues, our eyes are spaced a number of centimeters apart, so when looking at any object the eye send information to brain from two slightly different perpectives. The brain interprets this information and combines the two images to create depth perception and see one 3 dimensional image.

Stereoscopy originally involved taking a single image, and adding two additional image layers with slightly different perspectives. One layer was tinted red and the other blue. When watching a 3D movie, the audience would wear cardboard 3D glasses that had one red and one blue lens. Each lens would filter out its similarly colored image layer, thereby tricking the brain into creating a 3D image by mashing the two images together. 




Stereoscopy








Stereoscopy is most widely accepted method for capturing and delivering 3D video. It involves capturing stereo pairs in a two-view setup, with cameras mounted side by side, separated by the same distance as between a person's pupils. 

If we imagine projecting an object point in a scene along the line-of-sight (for each eye, in turn) to a flat background screen, we may describe the location of this point mathematically using simple algebra. In rectangular coordinates with the screen lying in the Y-Z plane (the Z axis upward and the Y axis to the right) and the viewer centered along the X axis, we find that the screen coordinates are simply the sum of two terms, one accounting for perspective and the other for binocular shift. Perspective modifies the Z and Y coordinates of the object point by a factor of D/(D-x), while binocular shift contributes an additional term (to the Y coordinate only) of s*x/(2*(D-x)), where D is the distance from the selected system origin to the viewer (right between the eyes), s is the eye separation (about 7 centimeters), and x is the true x coordinate of the object point. The binocular shift is positive for the left-eye-view and negative for the right-eye-view. 

For very distant object points, it is obvious that the eyes will be looking along the same line of sight. For very near objects, the eyes may become excessively "cross-eyed". However, for scenes in the greater portion of the field of view, a realistic image is readily achieved by superposition of the left and right images (using the polarization method or synchronized shutter-lens method) provided the viewer isn't too near the screen and the left and right images are correctly positioned on the screen. Digital technology has largely eliminated inaccurate superposition that was a common problem during the era of traditional stereoscopic films.

Technologies..

There was another problem with these colorful anaglyph images, though. They altered the coloring of the movies and interpreting the different images would often cause headaches after a short time. This led to the creation of the polarized 3d glasses we see in cinemas today.but the 3d technology used in movies is different than what is used in homes.

To overcome the above problem, the newest glasses innovation is a LCD shutter glasses which work on a system known as 'active technology'. These active shutter glasses work by alternately blocking the vision in each eye in conjunction with the refresh rate of the display screen. 3D TVs that use this form will display alternate images with slightly differing perspectives at a high rate, and the glasses darken each lens in time with the alternating images, causing the brain to do the classic image mash-up.


This technology works in a similar fashion as the older glasses, by blocking what image enters which eye. Shutter glasses simply take the idea to the next logical step by literally blacking out the lenses at a high rate of speed. Subsequently, shutter glasses are able to offer a much clearer three-dimensional picture than older methods





















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