MECHINICAL TECHNIQUES

ADM and Canadian Bioenergy look at joint biodiesel project

2009-04-09T11:52:00.000-07:00

Negotiations to form a joint venture to construct and operate a 265 million litre/year (70 million gallon/year) canola-based biodiesel production facility were announced earlier this week (7th April) by Canadian Bioenergy Corporation and the Archer Daniels Midland Company. If successful the new plant will be built at the site of ADM’s canola crushing plant in Lloydminster, Alberta. The companies are in the process of undertaking a full feasibility analysis of the project.

Wind turbines raise property values in Texas

2009-04-09T11:51:00.000-07:00

Property values are soaring in West Texas community because of the hundreds of newly-built wind turbines.

According to the AP, the deals give the energy companies operating the turbines massive tax breaks. In return, the school districts get part of the savings.

As per the information available, Texas schools earn millions on wind generated on state land, depending on how many megawatts are produced and the current price of electricity. Texas schools benefit from the increase in wind farms, because like oil and gas production on state lands, wind farms on state lands are required to pay land usage fees plus a portion of revenues to the State's Permanent School Fund, which is constitutionally dedicated to the schoolchildren of Texas.

The AP report highlighted that the school district with an enrollment of 201, is among the dozens on Texas plains that “have cut deals allowing them to collect hundreds of millions of dollars from wind farms without sending any of the money to the state”. The deals have their basis in the Texas Economic Development Act, a 2001 law that allows school districts to offer tax breaks similar to those handed out by county and city governments. Such property is taxed at full value for two years and then at a limited value for eight. A negotiated portion of the savings is passed on to the district.

The money that is channeled back to the school districts is known as payments in lieu of taxes, or PILOT agreements.

The four projects already in place will allow the Sterling City school district, the only one in the county, to collect at least $47 million over the next decade as compensation for more than $100 million in tax breaks it gave to wind farm operators.

Rising property values tied to the wind farms have already allowed the district to pass an $11.2 million bond to pay for new elementary and middle schools, a new gym and other facility improvements.

Assessing the complexities associated with the designing of new turbine blades

2009-04-09T11:49:00.000-07:00

A key consideration that goes behind blade design and manufacturing is related to coming up with a reliable efficient power generation.

This means low maintenance of machinery, low variation in weight and mechanical performance of blades to reduce variable results and of course high power output in lower wind speeds to optimise the power curve.

Yet, blade failure, which is one of the main reasons behind wind turbine accidents, can arise due to numerous reasons or from possible sources, and results in either whole blades or pieces of blade being thrown from the turbine.

There are far too many blade failures, or blades in need of repair, replacement or a remedy, says David Cripps, Strategic Account Manager - Wind Energy, Gurit USA Inc.

“The work going on now in this respect is due to either manufacturing defects or design defects. In many cases, the defect has been caused by a valid design, but one that just proved impractical to manufacture to the tolerance level or accuracy required,” said Cripps.

Commenting on how much one can relate to the pressure to rapidly grow output from blade factories, Cripps said a lot has to do with the difficulty that new manufacturing teams can have with building to the accuracy, or defect level required, whilst it being driven to lower costs and increased production throughput.

“Also with the rapid rate of introduction of new blade designs, it is always possible that design errors creep in,” acknowledged Cripps.

According to experts from the industry, structural flaws have been encountered, particularly with the blades. Cracks sometimes appear soon after manufacturing. Mechanical failure, due to alignment and assembly errors, is common. Electrical sensors frequently fail because of the power surges. Non-hydraulic brakes tend to be reliable, but hydraulic braking systems often cause problems.

Manufacturing flaws can cause problems during normal operation. For example, it has been pointed out that blades can develop cracks at the edges, near the hub or at the tips. Fibre glass rotor blades have been considered to be the most susceptible components of a wind turbine. Typical manufacturing flaws in case of the blades may be summarised as delaminations, adhesive flaws and resin-poor areas.

Hydro-Hydraulic Energy Invention

2009-04-09T11:43:00.000-07:00

Pakistan inventor Sarfraz Ahmad Khan has been working hard to develop new hydro technologies like this hydro power invention. His latest concept features the run of river active setup of micro hydro power generation blended with basic principals of hydraulics. This concept explores the possibility of transmitting the (collective) mechanical power gained from run-of-river hydro setup by converting it into hydraulic pressure. The sum-up of hydraulic pressure will make the main generators work. The basic concept requires hydraulic systems that can help to us to gain some reasonably good mechanical advantages. The hydro-mechanics will convert the mechanical force into hydraulic pressure. The collective hydraulic pressure shall be utilized to rotate the generator shaft.

Why include the hydraulic system?
As we know, if we produce a run-of-river micro hydro active system, the cost may be lower but on the other hand the output is not very significant. If we produce a large number of hydro rotors we will require an equivalent numbers of generators. In this concept we will collect the mechanical energy of Rotors spinning by the effect of high velocity river, into the hydraulic pressure by the help of input pistons. The hydraulic pressure gained from multiple set-ups of run of river rotors can be collected in an active hydraulic pressure chamber. By using the interchanging valves this pressure can be consecutively transferred to the output pistons. So the output piston will work to rotate the shaft of generator.

The Chain Pump

2009-04-09T11:19:00.000-07:00

One of the inventions of greatest utility, which has spread from China throughout the world, so that its origins are no longer realized, is the square-pallet chain pump. As may be seen in the accompanying illustrations, it consists of an endless circulating chain bearing square pallets which hold water, earth, or sand. The pump can haul enormous quantities of water from lower to higher levels. Depending on how well the pallets were fitted to avoid leakage and on the sturdiness of the machine as a whole, the height that water can be raised by single pump is about fifteen feet. The chain pumps spread throughout China rapidly, so it's not possible to find out who invented it. But according to some historical articles, it could have been invented around the first century BC.

A wood cut printed in Exploritation of the Works of Nature in 1637, showing two men working a square-pallet chain pump by treadles.

A Chain Pump model

A Method of casting Specula for Reflecting Telescopes, so as to ensure perfect Freeness from Defects, at the same time enhancing the Brilliancy of the

2009-04-09T11:18:00.000-07:00

The object-glass was made by the celebrated Ramsden. When I was about fifteen I used it to gaze at the moon, planets, and sun-spots. Although this instrument revealed to me the general characteristic details of these grand objects, my father gave me a wonderful account of what he had seen of the moon's surface by means of a powerful reflecting telescope of 12 inches diameter, made by Short -- that justly celebrated pioneer of telescope making. It had been erected in a temporary observatory on the Calton Hill, Edinburgh. These descriptions of my father's so fired me with the desire to obtain a sight of the glorious objects in the heavens through a more powerful instrument than the spy-glass, that I determined to try and make a reflecting telescope which I hoped might in some degree satisfy my ardent desires.

I accordingly searched for the requisite practical instruction in the pages of the Encyclopedia Britannica, and in other books that professed to give the necessary technical information on the subject. I found, however, that the information given in books -- at least in the books to which I had access was meagre and unsatisfactory. Nevertheless I set to work with all earnestness, and began by compounding the requisite alloy for casting a speculum of 8 inches diameter. This alloy consisted of 32 parts of copper, 15 parts of grain tin, and 1 part of white arsenic. These ingredients, when melted together, yielded a compound metal which possessed a high degree of brilliancy. Having made a wooden pattern for my intended 8-inch diameter speculum, and moulded it in sand, I cast this my first reflecting telescope speculum according to the best book instructions. I allowed my casting to cool in the mould in the slowest possible manner; for such is the excessive brittleness of this alloy (though composed of two of the toughest of metals) that in any sudden change of temperature, or want of due delicacy in handling it, it is very apt to give way, and a fracture more or less serious is sure to result. Even glass, brittle though it be, is strong in comparison with speculum metal of the above proportions, though, as I have said, it yields the most brilliant composition.

Notwithstanding the observance of all due care in respect of the annealing of the casting by slow cooling, and the utmost care and delicate handling of it in the process of grinding the surface into the requisite curve and smoothness suitable to receive the final polish, -- I was on more than one occasion inexpressibly mortified by the sudden disruption and breaking up of my speculum. Thus many hours of anxious care and labour proved of no avail. I had to begin again and proceed da capo. I observed, however, that the surplus alloy that was left in the crucible, after I had cast my speculum, when again melted and poured out into a metal ingot mould, yielded a cake that, brittle though it might be, was yet strong in comparison with that of the speculum cast in the sand mould; and that it was also, judging from the fragments chipped from it, possessed of even a higher degree of brilliancy.

The happy thought occurred to me of substituting an open metal mould for the closed sand one. I soon had the metal mould ready for casting. It consisted of a base plate of cast iron, on the surface of which I placed a ring or hoop of iron turned to fully the diameter of the intended speculum, so as to anticipate the contraction of the alloy. The result of the very first trial of this simple metal mould was most satisfactory. It yielded me a very perfect casting: and it passed successively through the ordeal of the first rough grinding, and eventually through the processes of polishing, until in the end it exhibited a brilliancy that far exceeded that of the sand mould castings.

The only remaining difficulty that I had to surmount was the risk of defects in the surface of the speculum. These sometimes result from the first splash of the melted metal as it is poured into the ring mould. The globules sometimes got oxidised before they became incorporated with the main body of the inflowing molten alloy: and dingy spots in the otherwise brilliant alloy were thus produced. I soon mastered this, the only remaining source of defect, by a very simple arrangement. In place of pouring the melted alloy direct into the ring mould, I attached to the side of it what I termed a "pouring pocket;" which communicated with an opening at the lower edge of the ring, and by a self-acting arrangement by which the mould plate was slightly tilted up, the influx of the molten alloy advanced in one unbroken tide. As soon as the entire surface of the mould plate was covered by the alloy, its weight overcame that of my up-tilting counterpoise, and allowed the entire apparatus to resume its exact level. The resulting speculum was, by these simple arrangements, absolutely perfect in soundness. It was a perfect casting, in all respects worthy of the care and labour which I invested in its future grinding and polishing, and enabled it to perform its glorious duties as the grand essential part of a noble reflecting telescope!

A Method of "chucking" delicate Metal-work, in order that it may be turned with perfect truth

2009-04-09T11:14:00.000-07:00

In fixing portions of work in the turning-lathe, one of the most important points to attend to is, that while they are held with sufficient firmness in order to be turned to the required form, they should be free from any strain which might in any way distort them. In strong and ponderous objects this can be easily accomplished by due care on the part of an intelligent workman. It is in operating by the lathe on delicate and flexible objects that the utmost care is requisite in the process of chucking, as they are easily strained out of shape by fastening them by screws and bolts, or suchlike ordinary means. This is especially the case with disc-like objects. As I had on several occasions to operate in the lathe with this class of work I contrived a method of chucking or holding them firm while receiving the required turning process, which has in all cases proved most handy and satisfactory.

This method consisted of tinning three, or, if need be, more parts of the work, and laying them down on a tinned face-plate or chuck, which had been heated so as just to cause the solder to flow. As soon as the solder is cooled and set, the chuck with its attached work may then be put in the lathe, and the work proceeded with until it is completed. By again heating the chuck, by laying upon it a piece of red-hot iron, the work, however delicate, can be simply lifted off, and will be found perfectly free from all distortion.

I have been the more particular in naming the use of three points of attachment to the chuck or face-plate, as that number is naturally free from any risk of distortion. I have on so many occasions found the great value of this simple yet most secure mode of fixing delicate work in the lathe, that I feel sure that any one able to appreciate its practical value will be highly pleased with the results of its employment.

The same means can, in many cases, be employed in fixing delicate work in the planing-machine. All that is requisite is to have a clean-planed wrought-iron or brass fixing-plate, to which the work in hand can be attached at a few suitable parts with soft solder, as in the case of the turning lathe above described.

A Method of increasing the Effectiveness of Steam by super-heating it on its Passage from the Boiler to the Engine.

2009-04-09T11:12:00.000-07:00

One or the earliest mechanical contrivances which I made was for preventing water, in a liquid form, from passing along with the steam from the boiler to the cylinder of the steam-engine. The first steam-engine I made was employed in grinding oil colours for my father's use in his paintings. When I set this engine to work for the first time I was annoyed by slight jerks which now and then disturbed the otherwise smooth and regular action of the machine. After careful examination I found that these jerks were caused by the small quantities of water that were occasionally carried along with the current of the steam, and deposited in the cylinder, where it accumulated above and below the piston, and thus produced the jerks.

In order to remove the cause of these irregularities, I placed a considerable portion of the length of the pipe which conveyed the steam from the boiler to the engine within the highly heated side flue of the boiler, so that any portion of water in the liquid form which might chance to pass along with the steam, might, ere it reached the cylinder, traverse this highly-heated steam pipe, and, in doing so, be converted into perfectly dry steam, and in that condition enter the cylinder. On carrying this simple arrangement into practice, I found the result to be in every way satisfactory. The active little steam-engine thence-forward performed its work in the most smooth and regular manner.

So far as I am aware, this early effort of mine at mechanical contrivance was the first introduction of what has since been termed "super-heated steam" -- a system now extensively employed, and yielding important results, especially in the case of marine steam-engines. Without such means of supplying dry steam to the engines, the latter are specially liable to "break-downs," resulting from water, in the liquid form, passing into the cylinders along with the steam.

An Instrument for Measuring the Total and Comparative Expansion of all Solid Bodies.

2009-04-09T11:05:00.000-07:00

Professor Leslie, being engaged in some investigations in which it was essential to know the exact comparative total expansion in bulk of metals and other solid bodies, under the same number of degrees of heat, mentioned the subject in the course of conversation. The instrument at that time in use was defective in principle as well as in construction, and the results of its application were untrustworthy. As the Professor had done me the honour to request me to assist him in his experiments, I had the happiness to suggest an arrangement of apparatus which I thought might obviate the sources of error; and, with his approval, I proceeded to put it in operation.

My contrivance consisted of an arrangement by means of which the metal bar or other solid substance, whose total expansion under a given number of degrees of heat had to be measured, was in a manner itself converted into a thermometer. Absolutely equal bulks of each solid were placed inside a metal tube or vessel, and surrounded with an exact equal quantity of water at one and the same normal temperature. A cap or cover, having a suitable length of thermometer tube attached to it, was then screwed down, and the water of the index tube was adjusted to the zero point of the scale attached to it, the whole being at say 50deg of heat, as the normal temperature in each case. The apparatus was then heated up to say 200deg by immersion in water at that temperature. The expansion of the enclosed bar of metal or other solid substance under experiment caused the water to rise above the zero, and it was accordingly so indicated on the scale attached to the cap tube. In this way we had a thermometer whose bulb was for the time being filled with the solid under investigation, -- the water surrounding it imply acting as the means by which the expansion of each solid under trial was rendered visible, and its amount capable of being ascertained and recorded with the utmost exactness, as the expansion of the water was in every case the same, and also that of the instrument itself which was "a constant quantity."

In this way we obtained the correct relative amount of expansion in bulk of all the solid substances experimented upon. That each bar of metal or other solid substance was of absolutely equal bulk, was readily ascertained by finding that each, when weighed in water, lost the exact same weight.

James Nasmyth's Expansometer, 1826.

My friend, Sir David Brewster, was so much pleased with the instrument that he published a drawing and description of it in the Edinburgh Philosophical Journal, of which he was then editor.

WHAT IS METALLURGY

2008-12-11T01:28:00.000-08:00

Metallurgy and Materials Engineering is the science and technology of producing, processing and giving proper shape to metals and alloys and other Engineering Materials having desired propertiesthrough economically viable process. Metallurgy and Materials Engineering hasplayed a crucial role in the development of human civilization beginning with bronze-age some 3000 years ago when tools and weapons were mostly produced from the metals and alloys. This science has matured over millennia and still plays crucial role by supplying materials having suitable mechanical properties, corrosion resistance and reliability for almost all the industries including transport, construction, agriculture, textiles, chemical processing, power generation and so on. These days the discipline of metallurgical engineering usually also encompasses other engineering materials such as ceramics, plastics and composites. In Pakistan the progress of metallurgical industries has picked up since the establishment of Pakistan Steel Mills and other allied industries.

The Department of Metallurgy and Materials Engineering offers a four-year degree course titled Bachelor of Engineering in Metallurgy & Materials. The subjects of ore mining, iron and steel making, metallography and heat treatment, science of engineering materials form the basis for the degree course. However, other related subjects are also included in the course to make it versatile and integratable with other fields of engineering. Adequate laboratory facilities are also available in the field of material testing, metallography, casting, heat treatment, fabrication welding. A seminar hall-cum-library has also been established in the department to provide in house reference material for the faculty members and students. A computer Pentium-III P.C. lab. Consists Internet, E-mail and various application software facilities are present for students. The students have also to complete a project and dissertation in the final year involving research/special studies to give them more comprehensive experience of practical work and report writing.

2008-02-01T04:14:00.000-08:00

Forces

2008-02-01T03:39:00.000-08:00

Forces

Whether a force is the push of a motor or the pull of gravity or muscles, the important characteristics are the magnitude and direction of the force, and the mass and previous state of motion of the object being affected. By pushing on a moving car, one can either cause it to gain speed or come to a stop, depending on which direction the force is applied, and that same force applied to a feather would be expected to more drastically affect the motion of the feather.
It is common practice to determine the expected changes in motion that an object will experience due to a particular force with the aid of a "free body" diagram. A diagram can tell us at a glance in which direction we would expect an object to accelerate or decelerate. A free body diagram shows all of the forces acting on an object, even if their effects are balanced out by another force. We will use free body diagrams to consider different situations involving the lamp that you find at your lab station

One force that always acts on the lamp is gravity. This familiar force would accelerate the lamp downward toward the center of the earth if left unchallenged. However, when the lamp is placed on a table it does not move downward because the table holds it up. The lamp is pushing down on the table and the table is pushing up on the lamp. This pair of forces is an action-reaction pair: equal and opposite forces acting on two different objects in contact. The reaction force from the table is called the normal force because this force is oriented normal (perpendicular) to the surface of the table. The arrows representing the forces are labeled. The symbols over the labels remind us that the forces are vector quantities and that the direction in which the force is applied is important. The length of the force vector should be proportional to their magnitudes.

OVERVIEW

2008-02-01T03:34:00.000-08:00

The branch of physics that deals with the action of forces on matter is referred to as mechanics. All considerations of motion are addressed by mechanics, as well as the transmission of forces through the use of simple machines. In our class, the goal is a mechanical goal (placing blocks into a bin) and electronics are used to control the mechanics.
While it is not necessary to sit down and draw free body diagrams or figure out the static coefficient of friction between the LEGO tires and the game board, it is helpful to keep certain mechanical concepts in mind when constructing a robot. If a robot's tires are spinning because they do not grip the floor, then something must be done to increase the friction between the tires and the floor. One solution is to glue a rubber band around the circumference of the tire. That problem/solution did not require an in-depth study of physics. Simply considering the different possibilities can lead to more mechanically creative robots.
Describing motion involves more than just saying that an object moved three feet to the right. The magnitude and direction of the displacement are important, but so are the characteristics of the object's velocity and acceleration. To understand these concepts, we must examine the nature of force. Changes in the motion of an object are created by forces.