Torque ratio concept for combustion phasing detection of a spark ignited engine
This paper presents a method for estimating combustion phasing of a five cylinder, four stroke, spark ignited engine, equipped with a crankshaft based torque sensor. A new measure for combustion phasing based on the torque signal is derived for a single cylinder engine. The measure is called 50% torque ratio. A validation of the measure is done by comparing to the related cylinder pressure based 50% pressure ratio measure. A method is also presented to apply the torque ratio measure to a multi-cylinder engine. A physical model for the instantaneous torque measurement is described handling the torque contributions from all individual cylinders in all combustion phases. The torque contribution from the combusting cylinder is isolated and analyzed by the torque ratio method to find the combustion phasing. The multi-cylinder algorithm is validated on torque and cylinder pressure data from a five cylinder Volvo V70 engine.
SI-Engine Cylinder Pressure Estimation using Torque Sensors
In order to maximise engine efficiency it is of interest to find the peak pressure position (PPP) of the cylinder pressure when controlling combustion engines. Cylinder mounted pressure sensors can be used to measure the pressure, but these are expensive and suffer from limited durability. Alternative pressure estimation methods using cheaper and more durable sensors are needed. This paper shows the performance when estimating the cylinder pressure of a five cylinder SI-engine using a crankshaft integrated torque sensor. An engine model is constructed to be able to eliminate the torsional resonances in the sensed torque signal and the cylinder pressure is reconstructed using a parameterised pressure model. The performance of the estimator is studied in three different simulation cases. Finally, the performance based on measured torque is presented. Copyright © 2004 SAE International.
Cambodian refugee health care beliefs and practices.
Since 1975, when refugees from Vietnam, Laos, and Cambodia first began coming to the United States, many articles have been written about Southeast Asian or Indochinese refugees and health care. A careful review of the literature shows that most of these articles have one thing in common: they are written primarily about Vietnamese and do not address the unique health care beliefs and practices of Lao or Cambodian refugees.1 Although some beliefs and practices are common to most Southeast Asians, many are not. Understanding at least that differences exist, and hopefully what some specific differences are, will allow nurses and others to give better care to the various people commonly grouped together as Southeast Asians. This article will introduce readers to some Cambodian beliefs and practices related to health care. Of the principle refugee groups admitted to the U.S. since 1975, the Cambodians are presenting the greatest challenges to health care providers. Cambodians are usually poorly understood by Americans, their health status statistics are hidden among the broad category of "Asian-Pacific Islanders" or "Indochinese Refugees," and cultural and institutional barriers combine to make access to care an overwhelming problem. The end results, of course, are more problems and more expense for the Cambodians, increased stress placed on an already terribly overstressed people, and ultimately greater demands and expense placed on the health care system. One of the most common misunderstandings about Cambodians is that they (and Lao) are basically the same as the Vietnamese. "They speak the same dialect don't they?" There are some similarities, but there are also very significant differences.