Effects of Exhaust Gas Recirculation on the Homogeneous Charge Combustion Process of n-Heptane at Different Load Conditions

Effects of exhaust gas recirculation （ EGR） on homogeneous charge combustion of n-heptane was studied through simulation and experiment. Experiments were carried out in a single cylinder, four-stroke, air cooled engine and a single cylinder, two-stroke, water cooled engine. In the four-stroke engine, experiments of the effects of EGR were examined using heated N2 addition as a surrogate for external EGR and modifying engine to increase internal EGR. The ignition timing was sensitive to EGR due to thermal and chemical effects. EGR or extra air is a key factor in eliminating knock during mid-load conditions. For higher load operation the only way to avoid knock is to control reaction timing through the use of spark ignition. Experimental and modeling results from the twostroke engine show that auto-ignition can be avoided by increasing the engine speed. The twostroke engine experiments indicate that high levels of internal EGR can enable spark ignition at lean conditions. At higher load conditions, increasing the engine speed is an effective method to control transition from homogeneous charge compression ignition （ HCCI） operation to non-HCCI operation and successful spark ignition of a highly dilute mixture can avoid serious knock.     

Letter writing instruction for children: Case-sensitive letter frequencies in children’s handwriting workbooks

Reading and Writing - Children’s ability to write letters automatically has been linked to academic achievement. Despite the importance of handwriting, handwriting instruction is often...     

Theory and application of preproduction testing

Summary and Conclusion A showing, to a small audience, before production has begun, may be useful to give a film maker advance information about the reactions of an audience to his film. Such tests are most useful when used early in the process of production, but not before the material available for showing to the test audience bears a systematic resemblance to the finished film. In most cases, the story board is the earliest stage at which a film may be tested, although exceptions are found to this rule. Testing cannot be utilized unless the producer's intent and the target audience are specified, and is most apt to be profitable when the content is very complex or when the production unit has had no experience with a topic or technique. Useful information may be obtained by any alert producer, but if the target audience is heterogeneous or has not been clearly specified, or if precise and careful predictions are needed, the services of poll and survey specialists or a phsychological test constructor should be sought. The production of a motion picture, as anyone who has attempted it knows, involves a series of decisions. Preproduction testing may be viewed as a sort of “decision insurance” which, although it does not guarantee the desired outcomes, increases the probability of their occurrence. In the preceding article, Hoban pointed out the need for prerelease evaluation of educational communications. This paper presents a theory and a technique for the application of such evaluation. Nicholas Rose is chief clinical psychologist, Wadsworth Hospital, Veterans' Administration Center, Los Angeles. He was formerly research director at the Department of Cinema, University of Southern California. Charles Van Horn is research associate, Department of Cinema, University of Southern California.     

Towards a framework for creative online collaboration: A research on challenges and context

The OnCreate project was initiated by ten universities with expertise in collaborative work in online-based learning environments and explores the specific challenges of implementing university courses in creative disciplines in such an environment. The first research phase comprises a literature search on creativity and its contextual factors in online collaboration in an educational setting. From this research a first set of possible key challenges and contextual key factors has been selected and applied to categorize the results of interviews and surveys on current good practice in creative online collaboration among experienced online teachers from the partner universities. From the key findings we formulate hypotheses to guide future research towards a framework for creative online collaboration. At the same time, the results can serve as inspiration for the educational practice. Notable observations of the good practice research among the partner universities are that they realise innovative collaboration concepts usually on mashed-up environments of state-of-the-art web services rather than on the omnipresent learning management systems (such as Moodle or Blackboard). Also, they show a paradigm shift from teaching to coaching and promotion of an open peer-review culture among the students.