Positive Displacement Pump (Lobe Pump)

A positive displacement pump causes a fluid to move by trapping a fixed amount of it then forcing (displacing) that trapped volume into the discharge pipe. Positive displacement pumps, unlike centrifugal or roto-dynamic pumps, will produce the same flow at a given speed (RPM) no matter what the discharge pressure.
One practical difference between dynamic and positivedisplacement pumps is their ability to operate under closed valve conditions.
Positive displacement pumps physically displace the fluid; hence closing a valve downstream of a positive displacement pump will result in a continual build up in pressure resulting in mechanical failure of either pipeline or pump. Dynamic pumps differ in that they can be safely operated under closed valve conditions (for short periods of time).
It is called so because replacing equal quantity of liquid from cavity is called positive displacement.

HOW BRAKES STOP VEHICLES

HOW BRAKES STOP VEHICLES

Brakes are an energy-absorbing mechanism that converts vehicle movement into heat while stopping the rotation of the wheels.
All braking systems are designed to reduce the speed and stop a moving vehicle and to keep it from moving if the vehicle is stationary.

Service brakes are the main driver-operated brakes of the vehicle, and are also called base brakes or foundation brakes.
Most vehicles built since the late 1920s use a brake on each wheel. To stop a wheel, the driver exerts a force on a brake pedal. Force on the brake pedal pressurizes brake fluid in a master cylinder.

This hydraulic force (liquid under pressure) is transferred through steel lines and flexible brake lines to a wheel cylinder or caliper at each wheel. Hydraulic pressure to each wheel cylinder or caliper is used to force friction materials against the brake drum or rotor.
The heavier the vehicle and the higher the speed, the more heat the brakes have to be able to absorb.

Long, steep hills can cause the brakes to overheat, reducing the friction necessary to slow and stop a vehicle

GLARE (Glass Laminate Aluminium Reinforced Epoxy)

GLARE (Glass Laminate Aluminium Reinforced Epoxy)

GLARE is a "Glass Laminate Aluminium Reinforced Epoxy" FML, composed of several very thin layers of metal (usually aluminium) interspersed with layers of glass-fibre "pre-preg", bonded together with a matrix such as epoxy. The uni-directional pre-preg layers may be aligned in different directions to suit the predicted stress conditions.

Although GLARE is a composite material,[1] its material properties and fabrication are very similar to bulk aluminum metal sheets. It has far less in common with composite structures when it comes to design, manufacture, inspection or maintenance. GLARE parts are constructed and repaired using mostly conventional metal material techniques.

Its major advantages over conventional aluminium are:
Better "damage tolerance" behaviour (especially impact and metal fatigue, as the elastic strain is larger than other metal material it can consume more impact energy. It is dented easier but has a higher penetration resistance )
Better corrosion resistance
Better fire resistance
Lower specific weight

Furthermore, it is possible to "tailor" the material during design and manufacture such that the number, type and alignment of layers can suit the local stresses and shapes throughout the aircraft. This allows the production of double-curved sections, complex integrated panels or very large sheets, for example.

While a simple manufactured sheet of GLARE will be more expensive than an equivalent sheet of aluminium, considerable production savings can be made using the aforementioned optimization. A structure properly designed for GLARE will be significantly lighter and less complex than an equivalent metal structure, and will require less inspection and maintenance and enjoy a much longer lifetime-till failure, making it a cheaper, lighter and safer option overall.

Applications
Besides the applications on the Airbus A380 fuselage, GLARE has multiple 'secondary' applications. GLARE is also the material used in the ECOS3 blast-resistant Unit Load Device. This is freight container shown to completely contain the explosion and fire resulting from a bomb such as that used over Lockerbie. Other applications include among others the application in the Learjet 45 and in the past also in cargo floors of the Boeing 737.

Current production
GLARE is currently produced by Cytec Engineered Materials in Wrexham, UK who supplies it to the Airbus A380 component manufacturing facilities at Stork Fokker in the Netherlands as well as at Airbus in Nordenham, Germany. Stork Fokker has opened a brand new facility next to its existing facilities in Papendrecht, the Netherlands. There Stork Fokker is able to produce Glare sheets of 4.5 x 11.5 m including the milling of doors windows etc. on a state-of-the-art 5-axis milling machine with a movable bed

TURBOCHARGER

TURBOCHARGER

A turbocharger,is a turbine-driven forced induction device that increases an internal combustion engine's efficiency and power output by forcing extra air into the combustion chamber.

The key difference between a turbocharger and a conventional supercharger is that a supercharger is mechanically driven by the engine, often through a belt connected to the crankshaft, whereas a turbocharger is powered by a turbine driven by the engine's exhaust gas. Compared to a mechanically driven supercharger, turbochargers tend to be more efficient, but less responsive. Twincharger refers to an engine with both a supercharger and a turbocharger.

Turbochargers are commonly used on truck, car, train, aircraft, and construction equipment engines. They are most often used with Otto cycle and Diesel cycle internal combustion engines. They have also been found useful in automotive fuel cells

DIRECT PETROL INJECTION

DIRECT PETROL INJECTION

This diagram shows the layout of the Bosch direct injection system. Direct injection systems differ from conventional port injection in several ways.

The fuel supply system uses two fuel pumps – a conventional electrical fuel pressure pump (in the past dubbed a high pressure pump but now referred to in this system as a low pressure pump) and a mechanically-driven high pressure pump. The low pressure pump works at pressures of 0.3 – 0.5 MPa while the high pressure pumps boost this very substantially to 5 – 12 MPa.

The high pressure fuel is stored in the fuel rail that feeds the injectors. The fuel rail is made sufficiently large that pressure fluctuations within it are minimised as each injector opens. The pressure of the fuel in the injector supply rail is controlled by an electronically-controlled bypass valve that can divert fuel from the high pressure pump outlet back to its inlet. The fuel bypass valve is varied in flow by being pulse-width modulated by the Electronic Control Unit (ECU). A fuel pressure sensor is used to monitor fuel rail pressure.

This diagram shows a cross-sectional view of an injector. Compared with a conventional port fuel injection system, the fuel injectors must be capable of working with huge fuel pressures and also injecting large amounts of fuel in very short periods. The reason for the much reduced time in which the injection can be completed is due to the fact that all the injection must sometimes occur within just a portion of the induction stroke. Conventional port fuel injectors have two complete rotations of the crankshaft in which to inject the fuel charge – at an engine speed of 6000 rpm, this corresponds to 20 milliseconds. However, in some modes, direct fuel injectors have only 5milliseconds in which to inject the full-load fuel. The fuel requirements at idle can drop the opening time to just 0.4 milliseconds. Direct injection fuel droplets are on average only one-fifth the droplet size of traditional injectors and one-third the diameter of a human hair.

The very lean air/fuel ratios at which direct injection systems can operate results in the production of large quantities of oxides of nitrogen (NOx). As a result, direct injected cars require both a primary catalytic converter fitted close to the engine, and also a main catalytic converter - incorporating a NOx accumulator - that is fitted further downstream.

MULTIPOINT FUEL INJECTION

MULTIPOINT FUEL INJECTION

Fuel injection is a method or system for admitting fuel into the internal combustion engine.There are basically two ways of admitting fuel one is through carburetor and other is fuel injection system.But presently the most used injection system are MPFI in petrol engine and CRDI in diesel engine.

Multi point fuel injection is a system wherein fuel is injected into individual cylinders based on commands from "on board engine management system computer"-popularly known as Engine control unit.ECU receives feed back from several sensors like engine speed sensor, fly wheel position sensor, vehicle speed sensor, atmospheric temp. sensor, accelerator pedal position sensor intake airflow sensor. Then ECU control the correct amount of fuel to be injected and the proper time at which the fuel will be injected at any speed and load condition. This ensure maximum power output at minimum fuel.


MPFI systems are of three types, first is BATCHED in which fuel is injected to the cylinders in groups, without precisely bringing together to any particular cylinder’s intake stroke, the second one is simultaneous in which fuel is injected at the same time to all the cylinders and the third one is sequential in which injection is timed to coincide with each cylinder’s intake stroke.

ADVANTAGES OF MPFI

• More uniform air-fuel mixture will be supplied to each cylinder, hence the difference in power developed in each cylinder is minimum. 
• The vibrations produced in MPFI engines is very less, due to this life of the engine component is increased. 
• No need to crank the engine twice or thrice in case of cold starting as happen in the carburetor system. 
• Immediate response, in case of sudden acceleration and deceleration. 
• The mileage of the vehicle is improved. 
• More accurate amount of air-fuel mixture will be supplied in these injection system. As a result complete combustion will take place. This leads to effective utilization of fuel supplied and hence low emission level. 

Relationship between the stress and strain

Relationship between the stress and strain

The relationship between the stress and strain that a particular material displays is known as that particular material's stress–strain curve. It is unique for each material and is found by recording the amount of deformation (strain) at distinct intervals of tensile or compressive loading (stress). These curves reveal many of the properties of a material (including data to establish the Modulus of Elasticity, E).

OPPOSED PISTON OPPOSED CYLINDER ENGINE

OPPOSED PISTON OPPOSED CYLINDER ENGINE

The basic OPOC engine consists of two cylinders on either side of a crankshaft. Multiple engines, or “modules,” can be used together to boost the fuel efficiency of a vehicle by as much as 45 percent. In addition to the efficiency gains of the engine itself, extra modules can be deactivated when they aren’t needed. Key to the design is an electrically controlled clutch, which disengages a module when necessary. Some modern V8 engines feature cylinder deactivation, but the pistons continue to turn due to their connection to the crankshaft, resulting in what’s known as “parasitic loss