Holiday...

It sort of feels stupid when you get back to typing things after a month, but it was something that i couldn't help much...my PC getting busted and a month-long series of examinations were the chief culprits responsible for this huge a gap. The best solution to all that crap was getting out of it, and I did the very same as soon as my exams got over...ran off to The Andamans. For folks who don't know what they are, they're a beautiful group of islands off the western coast of the country; picturesque beaches and islands and to top it all, an absolutely tension-free tropical climate!

The place was so damn good, despite my horrible cold I was able to enjoy it thoroughly. The Andaman & Nicobar Islands, as they're known officially are classified as a Union Territory. The capital Port Blair is the most populated place. A large faction of the populace comprises of Tamilians and Bengalis; I'm not sure of the exact distribution, but every second buy you meet is a Bengali and the guy after him is a Tamilian. There are a total of 570 islands of which only about 40 or so are inhabited. The islands are inhabited by different groups; the Shompen, Onge, Jarawa, and the Sentinelese. These tribes are almost on the brink of the extinction(especially the Onge who number about 97 only), but the're preserved thanks to the govt.'s initiatives.

I cannot write much about the history or about the above mentioned tribes because that wouldn't be the best way to respect either. To talk of the beauty around that area, the islands are a must see; at least once in your life...the place draws huge crowds of all kinds, honeymooners, families, foreigners...everyone. The white sand, blue sky and green waters are a wonderful treat for the eyes and the tropical climate is pretty refreshing... I think, more than my words, the picture could throw some light on what I'm trying to convey...

This Tropical Retreat was followed by witnessing The Great South Indian Wedding.....which involves usage of a 'military bugle' and 'military drums' for the entertainment purpose..I can assure you, that's loud enough to wake up the dead! Now back home, the college here's doing the best it can...expect frequent posts...ciao!

Entertainment for the Geeks...

Check out these wonderful videos...sure to please Electrical Geeks..

This one's about a 500KV line when opened on load...





This one's about how a transformer burns in the event of a short-circuit...

Talk of DC Machines!!

For all the difficulty in that goddamn subject called Electrical Machines, I think this video I got from metacafe gives a good feeling about it...

G-CON is the G-force control technology. The impact absorbing body structure of Honda cars is designed in response to the need to soften the impact of a collision from any direction.

To fight rear impact, the fuel tank has been placed beneath the front seats of the Honda City ZX - the safest area in the entire vehicle.

As a protection against front impact, Honda has used arch-shaped front side frames. This dramatically improves absorption of collision impact and helps to reduce deformation of the passenger compartment.

To withstand side impact, a floor cross member is located directly beneath the center pillar, without being offset.

That means the collision impact is largely absorbed by the floor. This helps protect the fuel tank and reduce passenger injuries.

With this post, I end my panegyrics of Honda's technologies (much to fish's relief...?)

The i-DSI engine..

Honda's intelligent Dual and Sequential Ignition (i-DSI) engine is the second i-Series engine, next to i-VTEC, that employs compact combustion chambers and two spark plugs per cylinder with individually controlled ignition timing for more rapid and complete combustion.

The purpose of the i-DSI engine is to achieve rapid and complete combustion. Narrower valve angles and other refinements have been employed to make the combustion chambers as compact as possible. The i-DSI engine employs an innovative twin spark plug system (two spark plugs per cylinder) for maximum combustion efficiency. In addition, the combustion chamber has been engineered to promote greater swirl of the air-fuel mixture.

The intake manifold shape has also been shaped and its length optimized. This results in optimizing the combustion process as a means of achieving high performance, high fuel economy and low toxic emissions.

Other refinements include world-leading friction reduction technology utilizing molybdenum-impregnated piston skirts, a rear-port exhaust system and an oblique-feed catalytic converter. And though the 1497 cc long-stroke engine has two valves per cylinder and only a single overhead camshaft, its output is a respectable 77Bhp at 5000 rpm with 125 Nm of torque peaking at a low 2700 rpm.

A little more auto-gyan...

CVT: The continuously variable transmission (CVT) is a transmission in which the ratio of the rotational speeds of two shafts, as the input shaft and output shaft of a vehicle or other machine, can be varied continuously within a given range, providing an infinite number of possible ratios. This can be achieved in a number of ways; after all, the concept of CVTs is not new to mankind..Da Vinci was the first one to design a CVT system. A few types of CVTs in use are:

Infinitely Variable Transmission (IVT)

A specific type of CVT is the infinitely variable transmission (IVT), which has an infinite range of input/output speed ratios in addition to its infinite number of possible ratios; this qualification for the IVT implies that its range of ratios includes a zero output/input speed ratio that can be continuously approached from a defined "higher" ratio. A zero output speed with a finite input speed implies an infinite input-to-output speed ratio, which can be continuously approached from a given finite input value with an IVT. Low gears are a reference to low ratios of output speed to input speed. This ratio is taken to the extreme with IVTs, resulting in a "neutral", or non-driving "low" gear limit, in which the output speed is zero, although, unlike neutral in a normal automotive transmission, the output torque may be non-zero: the output shaft is rigidly fixed at zero speed rather than being freely rotating. Most continuously variable transmissions are not infinitely variable.

Most IVTs result from the combination of a CVT with an epicyclic gear system (which is also known as a planetary gear system, and is termed a power split device in this applicaton) which enforces an output shaft rotation speed which is equal to the difference between two other speeds (perhaps multiplied by some gear ratio, depending on implementation). If these two other speeds are the input and output of a CVT, there can be a setting of the CVT that results in an output speed of zero. The maximum output/input ratio can be chosen from infinite practical possibilities through selection of additional input or output gear, pulley or sprocket sizes without affecting the zero output or the continuity of the whole system. The IVT is always engaged, even during its zero output adjustment.

The term "infinitely variable transmission" does not imply reverse direction, disengagement, automatic operation, or any other quality except ratio selectability within a continuous range of input/output ratios from a defined minimum to an undefined, "infinite" maximum. This means continuous range from a defined output/input to zero output/input ratio.

IVTs can in some implementations offer better efficiency when compared to other CVTs as in the preferred range of operation, most of the power flows through the planetary gear system and not the controlling CVT. Torque transmission capability can also be increased. There's also possibility to stage power splits for further increase in efficiency, torque transmission capability and better maintenance of efficiency of a wide gear ratio range.

Ratcheting CVT

The Ratcheting CVT is a Transmission that relies on static friction and is based on a set of elements that successively become engaged and then disengaged between the driving system and the driven system, often using oscillating or indexing motion in conjunction with one-way clutches or ratchets that rectify and sum only "forward" motion. The transmission ratio is adjusted by changing linkage geometry within the oscillating elements, so that the summed maximum linkage speed is adjusted, even when the average linkage speed remains constant. Power is transferred from input to output only when the clutch or ratchet is engaged, and therefore when it is locked into a static friction mode where the driving & driven rotating surfaces momentarily rotate together without slippage.

These CVTs can transfer substantial torque because their static friction actually increases relative to torque throughput, so slippage is impossible in properly designed systems. Efficiency is generally high because most of the dynamic friction is caused by very slight transitional clutch speed changes. The drawback to ratcheting CVTs is vibration caused by the successive transition in speed required to accelerate the element which must supplant the previously operating & decelerating, power transmitting element. An Infinitely Variable Transmission (IVT) that is based on a Ratcheting CVT and subtraction of one speed from another will greatly amplify the vibration as the IVT output/input ratio approaches zero.

Ratcheting CVTs are distinguished from Variable Diameter Pulleys (VDPs) and Roller-based CVTs by being static friction-based devices, as opposed to being dynamic friction-based devices that waste significant energy through slippage of twisting surfaces.

Variable-diameter pulley (VDP) or Reeves Drive

In this system, there are two V-belt pulleys that are split perpendicular to their axes of rotation, with a V-belt running between them. The gear ratio is changed by moving the two sections of one pulley closer together and the two sections of the other pulley farther apart. Due to the V-shaped cross section of the belt, this causes the belt to ride higher on one pulley and lower on the other. Doing this changes the effective diameters of the pulleys, which changes the overall gear ratio. The distance between the pulleys does not change, and neither does the length of the belt, so changing the gear ratio means both pulleys must be adjusted (one bigger, the other smaller) simultaneously to maintain the proper amount of tension on the belt.

Roller-based CVT

Consider two almost-conical parts, point to point, with the sides dished such that the two parts could fill the central hole of a torus. One part is the input, and the other part is the output (they do not quite touch). Power is transferred from one side to the other by one or more rollers. When the roller's axis is perpendicular to the axis of the almost-conical parts, it contacts the almost-conical parts at same-diameter locations and thus gives a 1:1 gear ratio. The roller can be moved along the axis of the almost-conical parts, changing angle as needed to maintain contact. This will cause the roller to contact the almost-conical parts at varying and distinct diameters, giving a gear ratio of something other than 1:1. Systems may be partial or full toroidal. Full toroidal systems are the most efficient design while partial toroidals may still require a torque converter (e.g., Jatco "Extroid"), and hence lose efficiency.

Hydrostatic CVTs

Hydrostatic transmissions use a variable displacement pump and a hydraulic motor. All power is transmitted by hydraulic fluid. These types can generally transmit more torque, but can be sensitive to contamination. Some designs are also very expensive. However, they have the advantage that the hydraulic motor can be mounted directly to the wheel hub, allowing a more flexible suspension system and eliminating efficiency losses from friction in the drive shaft and differential components. This type of transmission is relatively easy to use because all forward and reverse speeds can be accessed using a single lever.

Versatile Manufacturing first introduced hydrostatic drive in 400 swathers. Hydrostatic quickly became popular with swather and combines. Attempts to use hydrostatic in tractors however were less successful. IH hydro suffered from exxcessive cabin noise and many operators complained of not being able to rest their feet on the cab floor due to heat from the pump.

This type of transmission has been effectively applied to a variety of inexpensive and expensive versions of ridden lawn mowers and garden tractors. Many versions of riding lawn mowers and garden tractors propelled by a hydrostatic transmission are capable of pulling a reverse tine tiller and even a single bladed plow. Some heavy equipment may also be propelled by a hydrostatic transmission; e.g. agricultural machinery including foragers combines and some tractors. However, Hydrostats are usually not used for extended duration high torque applications due the heat that is generated by the flowing oil.

Next post, I'll try writing on the i-DSI engine...

Diwali

I guess doing all that research for finding out the other features about The Civic's engineering will take quite some time...meanwhile, lemme mention about something more happening in my life..



At this point I'm in Chennai with all my relatives and having a great time with them. It so happened that for the first time since my brother's entry in the family(that's well over two decades), we thought of taking a break from our breathless lives in Mumbai to spend our favourite festival with our relatives our here. So the festival of lights was pretty different and beautiful this time thanks to the company around me.



The best and simplest definition of the festival is the one that's known to the kids: eat a lot of sweets and blow really loud crackers. Being in a place which is pretty much orthodox, the effects were profound. At our paternal house we were made to eat all the sweets that we've missed all these years. That would have been enough to get me diabetic in a day. We woke up on the festival day to the sounds of really loud crackers that gave me the feeling of being in Basra or Tikrit. When I was having my bath I could see small pebbles move around due to the impetus provided by the explosives; fun, nonetheless. But it ceased to be fun when one of those confounded crackers hit my granny right in the eye. That gave all of us a really tough time. but thankfully, it was short lived. Meanwhile, my aunts saw to it that I gained a few pounds eating their elaborate meals.



It so happened that BigB had to leave in a short while, so the day I'd been to see him off, I joined my uncle's family and had great fun there. Slept everyday for about 9-10 hours from about 3:30 in the morning to 12:00 in the noon. I woke up to the greetings of "good afternoon!" rather than "good morning!". The breakfast was the lunch. Saw a number of movies(will write about them shortly). Currently my movie plans stand interrupted owing to those willing to chat rather than see the mindless noise of gunshots. Anyways, the sad thing is that today's my last day here, but it's not very painful coz it's home sweet home back in Mumbai when I land there on monday morning. Looking forward to it!