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Methods to improve efficiency of fourstroke, spark ignition engines at part load Abstract The  four stroke , spark ignition (SI)  engine  pressure–volume diagram ( p – V ) contains two main parts. They are the compression–combustion–expansion (high pressure loop) and the exhaust-intake (low pressure or gas exchange loop) parts. The main reason for  efficiency  decrease at part load conditions for these types of engines  is the flow restriction at the cross sectional area of the intake system by partially closing the throttle valve, which leads to increased pumping losses and to increased low pressure loop area on the  p – V  diagram. Meanwhile, the poorer combustion quality, i.e. lower combustion speed and cycle to cycle variations, additionally influence these pressure loop areas. In this study, methods for  increasing efficiency  at part load conditions and their potential for practical use are investigated. The study also includes a review of the vast literature on the solut

the abs system - overview An ABS system consists of the following components: Some wheel speed sensors Brake calipers A hydraulic motor Some pressure release valves A quick thinking computer (or control module) which coordinates the whole process Diagram 1: Brake caliper (1) and wheel speed sensor (2) how abs works When the driver hits the brakes this pressurises a hydraulic system which causes the brake pads to squeeze against the discs which causes the car to slow down. If the ABS system detects that one wheel is slowing down more rapidly than the rest (a symptom of wheel-lock) it automatically reduces the brake pressure on this wheel by opening a pressure release valve in the hydraulic system. ABS also has the ability to build the pressure back up via the hydraulic motor. The system reacts remarkably quickly, and compared wheel speeds many times a second. ABS systems can act on just the front wheels (which do most of the braking work), or all four depending on what

COLUMBUS, Ohio A study of muffler technology at Ohio State University is giving American automakers new options for designing quieter cars. Ahmet Selamet For more than a decade, Selamet and his colleagues have developed computer-based tools and specialized equipment for improving auto exhaust systems. The challenge, he said, is to control noise and exhaust emissions without blocking the flow of exhaust gases from the engine. Selamet also said that glass fiber can better withstand the high temperatures produced in modern exhaust systems, and potentially even insulate the car from that heat. The ultimate silencing device is a potato in the tailpipe, Selamet said with a laugh. But of course engines need to breathe to work properly, so we have to be more creative. Owens Corning recently asked Selamet to test and redesign a European muffler system that contained glass fiber stuffing. His task was to reduce the design complexity, reduce the weight of the syste