Hydraulics Pneumatics Essays

Hydraulics Pneumatics Essays Hydraulics Pneumatics Essay Hydraulics Pneumatics Essay HYDRAULICS IN MISSILES Nowadays, the electro-hydraulic actuator plays an important role in some modern tactical missiles. High power, great robustness and high tracking precision are the most significant demands for the missile actuator. Therefore an advanced method of active disturbance rejection control (ADRC) is presented aiming at the dynamics of the system are highly nonlinear and have large extent of model uncertainties, such as tremendous changes in load. Firstly, a novel ADRC controller is designed for estimating and compensating disturbance based on the mathematical model of missile electro-hydraulic actuator. Then, the influence of rudder load on the system performance is analyzed in this paper. Simulation results show that the ADRC control approach can decrease the tracking error and enhance the robustness of missile electro-hydraulic actuator system when the rudder load changed tremendously. But the phenomenon of Anti-Control has disadvantageous effect on the transition period of actuator loop and evenly causes the system divergence. HYDRAULIC SUSPENSION IN BOGIES The application of oil-hydraulic actuators for active suspension of railway vehicles has been examined experimentally by using a 3-DOF half-vehicle model. The LQG control law was adopted, in which state variables were estimated from measurable ones on the actual railway vehicle. The results show the possibility that the controllable frequency range extends with the oil-hydraulic actuator. The addition of bogie acceleration measurement to body related measurement provides a significant advantage for the performance. When actual body weight becomes lighter than that of the controller design value, the control performance and the stability deteriorate. Therefore, it is recommended to use the empty car body weight for design of the active suspension controller. The control effect can reach to the maximum vibration isolation level by shortening the sampling period to 2 ms PNEUMATIC GREASE GUN A grease gun is a common workshop and garage tool used for lubrication. The purpose of the grease gun is to apply lubricant through an aperture to a specific point, usually on agrease fitting. The channels behind the grease nipple lead to where the lubrication is needed. The aperture may be of a type that fits closely with a receiving aperture on any number of mechanical devices. The close fitting of the apertures ensures that lubricant is applied only where needed. There are three types of grease gun: A grease gun (pneumatic) 1. Hand-powered, where the grease is forced from the aperture by back-pressure built up by hand cranking the trigger mechanism of the gun, which applies pressure to a spring mechanism behind the lubricant, thus forcing grease through the aperture. 2. Hand-powered, where there is no trigger mechanism, and the grease is forced through the aperture by the back-pressure built up by pushing on the butt of the grease gun, which slides a piston through the body of the tool, pumping grease out of the aperture. . Air-powered (pneumatic), where compressed air is directed to the gun by hoses, the air pressure serving to force the grease through the aperture. Russell Gray, inventor of the air-powered grease gun, founded Graco based on this invention The grease gun is charged or loaded with any of the various types of lubricants, but usually a thicker heavier type of grease is used. It was a close resemblance to contemporary hand-power ed grease guns that gave the nickname to the World War II-era M3 submachine gun. PNEUMATICS IN AIRCRAFT Bleed air in gas turbine engines is compressed air taken from within the engine, after the compressor stage(s) and before the fuel is injected in the burners. While in theory bleed air could be drawn in any gas turbine engine, its usage is generally restricted to jet engines used in aircraft. Bleed air is valuable in an aircraft for two properties: high temperature and high pressure (typical values are 200-250Â °C and 275 kPa (40 PSI), for regulated bleed air exiting the engine pylon for use throughout the aircraft). 1] This compressed air can be used within the aircraft in many different ways, from de-icing, to pressurizing the cabin, to pneumatic actuators. However, bleed air is quite hot and when being used in the cabin or other low temperature areas, it must first be cooled or even refrigerated by the aircrafts environmental control system (ECS). Newer aircraft rely more on electricity, reducing the need for compressed air. Since most gas turbine engines use multiple compressor stages, some newer engines have the bleed air inlet between compressor stages to reduce the temperature of the compressed air.

Heres How Crabs Find Food

Here's How Crabs Find Food Crabs may be a favorite food for some people, but they need to eat too. They often live in dark or muddy areas, where it can be difficult to find prey by eyesight. So how do crabs find food, and how do they eat? And, interestingly, what types of food do they like to eat? How Crabs Find Food Like many other marine animals, crabs rely on their sense of smell to find prey. Crabs have chemoreceptors that allow them to detect chemicals in the water that are released by their prey. These chemoreceptors are located on a crabs antennae. These are long, segmented appendages near the crabs eyes that have both chemoreceptors and allow them to feel its surroundings. Crabs also have antennules, shorter antenna-like appendages near the antennas that allow them to sense their environment. A crab can taste using hairs on its mouthparts, pincers and even its feet. Senses of Taste and Smell Crabs have pretty well-developed senses of taste and smell. Fishing for crabs, or crabbing, using pots and cages relies on these senses, and makes it possible to catch crabs. The pots are baited with a variety of smelly things, depending on the target crab species. Bait can include chicken necks, pieces of fish such as eel, menhaden, squid, herring and mackerel. As the bait hangs in the trap in a bag or in a bait jar, odorous chemicals waft out into the ocean, attracting hungry crabs. Depending on water flow, these conditions can affect their senses to detect prey. What and How Crabs Eat Crabs arent picky eaters. They will eat everything from dead and living fish to barnacles, plants,  snails, shrimp, worms and even other crabs. They use their claws to grab food particles and put the food into their mouths. This is similar to the way humans eat using their hands or utensils. Crabs also use their claws to manipulate or break up the food so they can place it into their mouths more easily in smaller bites. When crabs have to break through shells of other sea life, their strong claws come in especially handy while their other appendages help them quickly move to catch various types of prey. Different Crabs, Different Diets Different crabs like to eat different types of sea life and plants.  Dungeness crabs, for example, may snack on squid and worms, while king crabs like to nosh on clams, mussels, worms and sea urchins. Basically, king crabs hunt for prey on the ocean floor and often eat decaying animal matter as well as live sea life. Sources and Further Reading â€Å"Frequently Asked Questions.†Ã‚  Blue Crab.â€Å"Encyclopedia of Tidepools and Rocky Shores.† Edited by Mark W. Denny and Steve Gaines, University of California Press, 2017.â€Å"Dungeness Crab.  Oregon Agriculture in the Classroom..Blue Crab Anatomy web.vims.edu.