Search results

The development of a theoretical model for predicting the combustion, performance and emission characteristics of a cylinder head porous medium engine becomes necessary due to imposed requirements from the viewpoint of power, efficiency and toxic gases in the exhaust. The cylinder head porous medium engine was found to have superior combustion, performance and emission characteristics when compared to a conventional diesel engine. The paper aims to discuss these issues.

Due to heterogeneous and transient operation of diesel engine under conventional and porous medium mode, the combustion process becomes complex, and achieving a pure analytical solution to the problem was difficult. Although, closer accuracy of correlation between the computer models and the experimental results is improbable, the computer model will give an opportunity to quantify the combustion and heat transfer processes and thus the performance and emission characteristics of an engine.

In this research work, a theoretical model was developed to predict the combustion, performance and emission characteristics of a cylinder head porous medium engine through two-zone combustion modeling technique, and the results were validated through experimentation.

The two-zone model developed by using programming language C for the purpose of predicting combustion, performance and emission characteristics of a porous medium engine is the first of its kind.

Middle level teachers, at times, link historical content with relevant English literature in interdisciplinary units. Elementary teachers periodically employ history-themed literature during reading time. Interconnections between language arts and history are formed with developmentally appropriate literature for students. Historical misrepresentations, however, proliferate in children’s literature and are concealed behind engaging narratives. Since literacy and historical thinking are essential skills, children’s literature should be balanced within, not banished from, the classroom. Using America’s peculiar institution of slavery as a reference point, this article examines children’s literature, identifies almost a dozen areas of historical misrepresentation, and proffers rich primary source material to balance the various misrepresentations. We provide teachers with reason for caution when including such literature; but also model how to locate, use, and, at times, abridge primary source material within an elementary or middle level classroom. Such curricular supplements provide balance to engaging but historically-blemished children’s literature and enable educators to attain the rigorous prescriptions of Common Core.

The purpose this experimentation is to study the combustion characteristics of compression ignition engine fuelled with mineral diesel. The reason behind the numerical simulation is to validate the experimental results of the combustion characteristics.

The numerical analysis was carried out in this study using MATLAB Simulink, and the zero dimensional combustion model was applied to predict the combustion parameters such as in cylinder pressure, pressure rise rate and rate of heat release.

Incorporating the dynamic combustion duration with respect to variable engine load in the zero dimensional combustion model using MATLAB Simulink reduced the variation of experimental and numerical outputs between 5.5 and 6 per cent in this analysis.

Validation of the experimental analysis is very limited. Investigations were performed using zero dimensional combustion model, which is the very appropriate for analysing the combustion characteristics.

Existing studies assumed that the combustion duration period as invariant in their numerical analysis, but with the real time scenario occurring in CI engine, that is not the case. In this analysis, mass fraction burnt considering the dynamic combustion duration was incorporated in the heat transfer model to reduce the error variation between experimental and numerical studies.

This chapter examines factors impacting vocabulary development in preschool dual language learners, providing a cultural and linguistic perspective on vocabulary instruction in this population. Through a multidisciplinary review of the research literature, instructional strategies that can support vocabulary development in this population are identified. The chapter concludes with a detailed illustration of how these strategies can be incorporated into a culturally linguistically responsive vocabulary approach for Latino preschoolers.

The purpose of this paper is to present a methodology to improve decision making about investments that reduce buildings' energy consumption.

A three‐stage methodology was developed and tested to analyse an existing Australian office building's energy use, its energy rating, and its life cycle investment. In total, seven cases of sets of improvements were modelled for energy performance. Their investment value was evaluated using a life cycle‐based analysis across several investment options.

A holistic approach to investment shows that the most effective sustainable refurbishments need not be the most expensive. Optimised investment can take advantage of the timing of both re‐investment in component renewal and efficiency gains from the refurbishment. Furthermore, relatively small changes in income can offset capital expenditure for refurbishments and protect against obsolescence.

Much work on sustainable refurbishments rarely considers the investment basis, across a life cycle, of that expenditure, generally seeing them as a cost and rarely considers the optimal time for that expenditure in the asset life cycle. This paper addresses both concerns.

WITH this issue we are commencing the twenty‐seventh year of our career as an independent Library Journal and trust that we shall carry on the tradition of our illustrious founder and continue to criticise or praise without fear or favour. During the past twelve months our editorial staff has successfully produced special numbers dealing with Bookbinding, Book Selection, Children's Departments, Classification, and Colonial Libraries. Judging by the correspondence we have received, our efforts have been greatly appreciated by the majority of our readers. Naturally we have not pleased everybody and we have even been dubbed the “little contemporary” in some quarters. However, we can point to an unbroken record of twenty‐six years' endeavour to serve the library profession and we ourselves are justly proud of the contemptible “little contemporary” that did not cease to appear even during the darkest hours of the dread war period.

‘Bow and Twist’ is a phrase that is commonly used to cover all forms of non‐flat distortion in the PCB industry. The shape that distortions can assume are analysed and quantified; the size and shape of distortion are compared with the physical properties of the material that give rise to them. The special care needed in the manufacture of multilayer circuits is highlighted. The effects of more advanced material and of heatsinks are considered.

Spark ignition (SI) engines are used in a wide area in the transportation industry, from road vehicles to piston-prop aircraft. On the other hand, the decrease in reserves of fossil fuels used in SI engines and the increase in greenhouse gas emissions makes the use of alternative fuels inevitable. In this paper, optimization of in-cylinder combustion and engine performance parameters by intake-charge conditions [i.e. intake-air temperature, injection timing and exhaust gas recirculation (EGR)] in a hydrogen (H₂)-fueled small SI engine is performed.

Experimental studies were performed at a 1,600 rpm engine speed of a single-cylinder, air-cooled engine having a stroke volume of 476.5 cm³, maximum output power of 13 HP and torque of 25 Nm. The hydrogen-fueled SI engine was operated by a lean air-fuel mixture (ϕ = 0.6) under wide-open throttle (WOT) conditions.

The findings of the paper show that improvements can be achieved in in-cylinder combustion, indicated engine performance, exhaust NO_x emissions with optimum intake-air temperature, the start of H₂ injection and the ERG rate.

It has been determined that a 32°C intake-air temperature, 395°C (bTDC) start of H₂ injection, and 5%–10% EGR rates are the most suitable values for the examined hydrogen fueled SI engine.

Hydrogen is a usable alternative fuel for SI engines used in a wide area from road vehicles to piston-prop aircraft engines. However, a number of problems remain that limit hydrogen fueled SI engines to some extent, such as backfire, a decrease of engine power, and high NO_x emissions. Therefore, it is appropriate to examine the effects of intake-charge conditions on in-cylinder combustion, engine performance, and NO_x emissions parameters in a hydrogen fuelled SI engine.

This paper aims to determine the characteristics of board certification among US physicians and to test whether accounting for the expected gains to certification alters the pattern of the determinants of board certification.

Splitting the sample into sub‐samples by characteristics associated with certification/non‐certification identified in a probit, the incremental gain to certification from log‐earnings equations is identified. Realizing that these methods are susceptible to sample selection, correction is made for it using the Heckman approach. Using the sample selection corrected equations, the expected gain to certification among those who certify is then predicted and those who do not certify is then predicted and this difference is included as a proxy for the expected gain in the original probit to ascertain whether including the expected gain alters the determinants of certification.

Accounting for the expected gain alters the pattern of the determinants of certification. Although some groups such as blacks appear less likely to certify, after accounting for their expected return to certification, they are not as less likely. This is explained in terms of the expected marginal return to certification, market structure and practice setting.

The data used in the analysis apply only to young physicians in the USA. Also, these results may be applicable only to the particular cohort used in this analysis.

The findings help to explain the absence of minority board certified physicians within the USA.

This paper is the first to simultaneously estimate the returns to physician board certification and the decision to obtain certification.