InDetail

अतीत   में   जो कुछ भी हुआ , वह  अच्छे के लिए   हुआ,   जो कुछ   हो रहा है ,  अच्छा हो रहा   है, जो   भविष्य में  होगा ,  अच्छा ही  होगा.  अतीत   के लिए   मत रोओ ,  अपने   वर्तमान जीवन   पर ध्यान केंद्रित करो ,   भविष्य   के लिए   चिंता मत करो   (Whatever happened in the past, it happened for the good; Whatever is happening, is happening for the good; Whatever shall happen in the future, shall happen for the good only. Do not weep for the past, do not worry for the future, concentrate on your present life.) जन्म के समय में   आप क्या   लाए थे जो अब खो दिया है?  आप ने  क्या पैदा किया था  जो नष्ट हो गया है?  जब  आप   पैदा हुए थे,  तब  आप कुछ भी  साथ  नहीं लाए थे.    आपके पास   जो कुछ भी है,    आप  को  इस धरती   पर  भगवान ...

HUMMINGBIRDS VS. HELICOPTERS A quantitative analysis of hummingbird wings shows that they generate lift more efficiently than the best microhelicopter blades. The findings could lead to more powerful, bird-inspired robotic vehicles. More than 42 million years of natural selection have turned hummingbirds into some of the world's most energetically efficient flyers, particularly when it comes to hovering in place. Humans, however, are gaining ground quickly. A new study led by  David Lentink , an assistant professor of  mechanical engineering  at Stanford, reveals that the spinning blades of microhelicopters are about as efficient at hovering as the average hummingbird. The experiment involved spinning hummingbird wings – sourced from a pre-existing museum collection – of 12 different species on an apparatus designed to test the aerodynamics of helicopter blades. The researchers used cameras to visualize airflow around the wings, and sensitive load cells to measu...

The first benefit offered by all forms of CNC machine tools is improved automation. The operator intervention related to producing workpieces can be reduced or eliminated. Many CNC machines can run unattended during their entire machining cycle, freeing the operator to do other tasks. This gives the CNC user several side benefits including reduced operator fatigue, fewer mistakes caused by human error, and consistent and predictable machining time for each workpiece. Since the machine will be running under program control, the skill level required of the CNC operator (related to basic machining practice) is also reduced as compared to a machinist producing workpieces with conventional machine tools. The second major benefit of CNC technology is consistent and accurate workpieces. Today's CNC machines boast almost unbelievable accuracy and repeatibility specifications. This means that once a program is verified, two, ten, or one thousand identical workpieces can be easily produce...

The real parts of a CNC program involves the input of co-ordinates of the tool endpoint to produce any machining profile, subsequently it is necessary to follow a proper co-ordinate system. Cartesian Co-ordinate System: All the machine tools make use of the Cartesian coordinate system for the purpose of simplicity. The guiding coordinate system followed for assigning the axes is the familiar right hand coordinate system. The fundamental axes to be assigned are the rectangular axes and the rotary axes. One could use his right hand to arrive at these alternate variable positions of the same right hand coordinate system. Designating the axes: Z-Axis and Motion: Location: The Z-Axis movement is either along the shaft pivot axle or parallel to the shaft pivot axle. In the case of machine without a shaft / spindle such as shapers and planers, it is identified as the one perpendicular to the table, which passing through the controlled point (e.g., the cutting tool tip). ...

Engineers have long used stress-strain curves to uncover a host of material properties. The curves are created by plotting the results of tensile strength tests of material samples, putting stress (force divided by area) on the y-axis and strain (stretch divided by gage or original length) on the x-axis. Some of the key material properties the curve can reveal include the material’s elastic limit, along with the elastic and plastic ranges, the yield point, ultimate and rupture strengths, and the moduli of resilience and toughness. Sometimes, however, engineers must interpolate between data points to get those performance figures. Often a stiffness-strain curve tensile test result defines some material properties more precisely cut—no interpolating or “guesstimation” needed. It puts stiffness (change in stress divided by change in strain) on the y-axis and strain on the x-axis. In effect, it graphs the slope of the stress-strain curve as a function of strain. The two graphs on...

The conservation of energy Gobble down five bananas and you'll have enough  energy  to swim for about an hour. That's because your body is a complex machine capable of turning one kind of energy (food) into another kind (movement). Cars can pull off the same trick. Depending on which make and model you own, you probably know that it does so many kilometres or miles to the gallon; in other words, using a certain amount of energy-rich gasoline, it can transport you (and a moderate load) a certain distance down the road. What we have here are two examples of  machines —the human body and the auto-mobile—that obey one of the most important laws of physics: the  conservation of energy . Written in its simplest form, it says that you can't create or destroy energy, but you can convert it from one form into another. Pretty much everything that happens in the universe obeys this fundamental law. But why, and what use is it anyway? Let's take a clo...

How do planes fly? If you've ever watched a jet plane taking off or coming in to land, the first thing you'll have noticed is the noise of the engines.  Jet engines , which are long metal tubes burning a continuous rush of fuel and air, are far noisier (and far more powerful) than traditional  propeller  engines. You might think engines are the key to making a plane fly, but you'd be wrong. Things can fly quite happily without engines, as gliders (planes with no engines), paper planes, and indeed gliding birds readily show us. Photo: Four forces act on a plane in flight. When the plane flies horizontally, lift from the wings exactly balances the plane's weight. But the other two forces do not balance: the thrust from the engines pushing forward always exceeds the drag (air resistance) pulling the plane back. That's why the plane moves through the air. Photo by Kemberly Dawn Groue courtesy of US Air Force. If you're trying to understand how planes fly, ...