BUET ENGINEERS

  Most developing countries have abundant renewable energy resources, including solar energy, wind power, geothermal energy, and biomass, as well as the ability to manufacture the relatively labor-intensive systems that harness these. By developing such energy sources developing countries can reduce their dependence on oil and natural gas, creating energy portfolios that are less vulnerable to price rises. In many circumstances, these investments can be less expensive than fossil fuel energy systems. Renewable energy, often referred to as clean energy, comes from natural sources or processes that are constantly replenished. For example, sunlight or wind keep shining and blowing, even if their availability depends on time and weather. While renewable energy is often thought of as a new technology, harnessing nature’s power has long been used for heating, transportation, lighting, and more. Wind has powered boats to sail the seas and windmills to grind grain. The sun has provided warm

China is planning to build the world’s first solar power station in space to provide “inexhaustible clean energy” according  to a story  in  Science and Technology Daily,  the official newspaper of China’s Ministry of Science and Technology. They claim to be already testing the technology and intend to build the station by 2050. Xie Gengxin, deputy head of the Chongqing Collaborative Innovation Research Institute for Civil-Military Integration in Southwestern China, told the  China Daily  newspaper that a testing facility in Chongqing’s Bishan district is being built that will be used to test the theoretical viability of a space-based solar power station. The 33 acre test facility will develop space transmission technologies while studying the effect of microwaves beamed back to Earth on living organisms. The initial investment of 100 million yuan ($15 million) will be made by the Bishan district government and construction could take up to two years, but once it begins operati

 1) Steady & Unsteady Flows.  2) Uniform & Non-uniform Flows.  3) Laminar & Turbulent Flows.  4) Compressible & In compressible Flows.  5) Rotational & Ir-rotational Flows.  6) One , Two & Three Dimensional Flows. Steady & Unsteady Flows:-  Steady Flows:- In which the fluid Characteristics Like velocity, pressure, density , etc. At a Point do not change with time. Unsteady Flow:- In which the fluid velocity , pressure or density at a point changes with respect to time. Uniform & Non-uniform Flow :-  Uniform Flow:- In which the velocity at given time does not change with respect to space ( length of direction of the flow ). Non-Uniform Flow:- In which the velocity at any time changes with respect to space. Changing in space Laminar & Turbulent flows:-  Laminar Flow:- in which the fluid particles move along well defined paths or stream line. Fig. Laminar Flow Turbulent Flow:- fluid moves in very irregular paths or zig – za

Lagrangian Versus Eulerian Approach Lagrangian Approach Method of description that follows the particle is referred to as the Lagrangian method of description. In Lagrangian approach we analyze a fluid flow by assuming the fluid to be composed of a very large number of particles whose motion must be described. How to do it? Identify (or label) a material of the fluid; track (or follow) it as it moves, and monitor change in its properties. The properties may be velocity, temperature, density, mass, or concentration, etc in the flow field. Eulerian Approach In control volume analyses, it is convenient to use the field, or Eulerian, method of description, which focuses attention on the properties of a flow at a given point in space as a function of time. In the Eulerian method of description, the properties of a flow field are described as functions of space coordinates and time. How to do it? Identify (or label) a certain fixed location in the flow field and follow chang

The  Lagrangian Description  is one in which individual fluid particles are tracked, much like the tracking of billiard balls in a high school physics experiment. In the Lagrangian description of fluid flow, individual fluid particles are "marked," and their positions, velocities, etc. are described as a function of time. In the example shown, particles A and B have been identified. Position vectors and velocity vectors are shown at one instant of time for each of these marked particles. As the particles move in the flow field, their potions and velocities change with time, as seen in the animated diagram. The physical laws, such as Newton's laws and conservation of mass and energy, apply directly to each particle. If there were only a few particles to consider, as in a high school physics experiment with billiard balls, the Lagrangian description would be desirable. However, fluid flow is a continuum phenomenon, at least down to the molecular level. It is not possib

1. Drafters should use a ________ in a section view of a mechanical part that includes the cylindrical view of a threaded hole. A. Center line B. Hatch line C. Poly line D. Dimension line 2. The section view drawing in which one fourth of an object has been marked for removal is known as a ________ section. A. full B. half C. quarter D. none of the above  3. In offset sections, offsets or bends in the cutting plane are all: A. 90 degrees B. 180 degrees C. Either 90 or 180 degrees D. 30, 60, or 90 degrees 4. When filling an area with a hatch pattern in AutoCAD the drafter needs to be able to ________. A. see the entire bounding area to hatch B. set Ortho on C. turn ISO grid off D. set the layer to Defpoints