Flying V????

 

Most of us have probably seen large groups of birds flying in formation. These large groups of birds will typically fly in a large "V" shape with one bird in the lead and others trailing behind in two lines.

This formation flight is followed by the birds for two reasons.They are,

First reason :

                   The shape of the formation reduces the drag force that each bird experiences compared to if it were flying alone.

Second Reason :

                      Is that may explain why birds fly in formation is that this orientation allows the birds to communicate more easily. The V formation provides the birds with good visual contact of each other to keep the flock together. This communication minimizes the possibility of losing birds along the way as the formation crosses vast distances during migration.

Results:

Studies have estimated that a flock of 25 birds in formation can fly as much as 70% further than a solo bird using the same amount of energy.

By spacing themselves apart properly, birds can achieve optimum positions that reduce the drag of every bird in the formation. However, not all birds benefit equally.  Apex bird has to work the hardest since it flies into undisturbed air. The upwash(upward thrust) that this bird creates improves the aerodynamics of the two behind it, and these two further improve conditions for the next two birds in line. This means that birds in the middle experience less drag than either the lead bird or the bird at the end of each line.

 

Interesting Point : The birds at the apex and aft positions may interchange their positions after some time so that the flock can migrate to a longer distance.

Degrees of Freedom

Degrees of Freedom(dof)

“No. of parameters needed to specify completely the spatial pose of a rigid body”

A rigid body in ‘d’ dimensions has  d(d+1)/2 no. of degrees of freedom.

d(d+1)/2        =         d          +           d(d-1)/2

           (dof)                 (translations)          (rotations)

• A non-rigid body has infinite no. of dof.

In 3 dimensional space for a rigid body there are 6 dof.

 

• 6 dof:

1.  Moving up and down(heaving)

2.  Moving left and right( swaying)

3.  Moving forward and backward (pitching)

4.  Tilting forward and backward (pitching)

5.  Turning left and right( yawing)

6.  Tilting side to side (rolling)

Dof for a system: A system is defined to be a set of rigid bodies.Its dof can be calculated by

Dof of system = (Dof of bodies) –(internal constraints they may have on relative motion)

Here the dof represents the no. of parameters needed to specify the spatial pose of the system.  

Eg:1

A human arm has 7 dof.

    I.        Shoulder----3----pitch,yaw,& roll

   II.        Elbow--------1----pitch

  III.        Wrist----------3---pitch,yaw,roll 

·         Only 3 of these movements would be necessary to move the hand to any point in space. But people would lack the ability to group things form different angels or directions. 

·         Total no. of dof is 6 

·         A robot/object that has mechanisms to control all 6 physical dof is said to be holonomic 

·         An object with few dof is said to be non-holonomic. 

·         An object with more controllable Dof( than total dof) such as human arm is said to be redundant.

Eg:2

An air plane is a non-holomonic. Since it has only 4 dof

                    I.        Forward motion

                  II.        Rolling

                III.        Pitch (only some extent)

                IV.        Yaw

Eg:3

A car has max. of 15 dof

15 = 6 DOF for the car body+ 1 for each wheel's vertical motion+ 1 for each wheel spinning + 1 for the engine

Eg :4

A human wrist has 27 dof .

• It is the most complicated design that ever made on the earth and it is the system which has the max. no of dof.

•  4 in each finger ( 3 for extension and flexion and one for abduction and adduction)                                     =                                4 x 4

•  the thumb is more complicated and has 5 Dof     = 5

• 6 DOF for the rotation and translation of the wrist =  6

                                                                                           -------------

                                                                                                 27        

                                                                                         -----------              

• Human Hand Not only design but also animating the wrist movements is so difficult such that they animate with only 12 dof neglecting the 15 other dof.

• It clearly unclouded that He is the best designer than any one who born on the earth

Gyro Wheel

Hi

Friends, None of you have learnt the bicycle without facing the wounds. But this generation has the opportunity to enjoy the same but without the wounds. This is possible by only the GYRO Bike which has the self balancing capacity and based upon the  Gyroscopic Principle. 

 For Video assistance click here

Training wheels are a thing of the past thanks to the revolutionary Gyrowheel. Gyrowheel not only keeps the bike from falling over, it also teaches correct riding technique. Gyrowheel senses unbalanced biking and re-centers the bike under the rider’s weight when the bike starts to wobble. Training wheels can’t do that!

Basic Thing

The magic is in the wheel! Okay, it’s not magic inside is a disk that spins independently of Gyro wheel. When the disk is turned on it creates a force the fancy term is “gyroscopic precession” that stabilizes the bike. Gyrowheel provides high stability at very low speed, making learning to ride easier, safer and a whole lot more fun!

WHAT IS PRECESSION AND WHY DOES GYROWHEEL WORK?
Gyrowheel essentially has a gyroscope inside. Gyroscopes are spinning wheels that exhibit a special property called precession. When a force is put at the top of a spinning wheel (such as a rider falling on a bicycle), rather than falling, the gyroscope simply turns, or precesses, in the direction of the fall. This occurs on normal bike wheels when the bike is traveling at higher speeds. Hence, it is easier to ride a bicycle once you "get going." Gyrowheel takes advantage of this property even when the bike is moving slowly. The disk inside Gyrowheel spins independently of the bike wheel. Thus, even when a rider is moving very slowly on the bicycle, the precession of Gyrowheel is still felt. If the rider begins to fall, Gyrowheel precesses under the rider's weight, restabilizing the bike.

Out of the Vortex

Many of us vexed with the conventional turbines which rotates to produce electricity. From my schooling whatever may be the type of generating power there is a rotation of turbine. And I begin to think is there any case to generate power with out the use of turbine and here is the case:

"Fluids passing over objects can set up vortices with potentially disastrous consequences.Technology can capture energy form the turbulent and convert it into clean, cheap electricity"

               When water flows over any structure vortex is created behind the object and it will have a lot of potentiallity. Because of the disruptive power of the vortex induces vibrations named to be vortex induced vibration (VIV), Engineers have long been interested in trying to spoil vortex shedding and suppress VIV to prevent damge to equipment and strucures. And it's amzing that almost no one has tried to tap their power.


for further details click here

Multi Body Dynamics

Multiple interconnected rigid bodies, is termed to be as Multi Body system.And dynamics concerned to the multibody systems is referred to as the "Multi Body Dynamics"