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A dynamic model of a multi-unit air conditioning (AC) system in a generic bus was developed to investigate different control strategies on the system performance and the cabin comfort level. In this study, a part-load condition was considered, where adopting a proper strategy for governing a multi-unit system is important. Simulink and Simscape toolbox from MATLAB (R2019a) were used to build up the real-time model by integrating a cooling system with a cabin sub-model. The cooling system consists of two independently controlled units, based on a Vapor Compression Cycle (VCC).The cabin is modelled using a moisture air network and is coupled with the cooling system to exchange heat with the refrigerant through the evaporators. Moreover, the sensible and latent loads are incorporated into the cabin by a thermal network. Six different strategies were implemented using different criteria to investigate the average power and Coefficient of Performance (COP) under a part-load condition. The comfort level was obtained in terms of the Predicted Mean Vote (PMV)and Predicted Percentage of Dissatisfied (PPD) indices. Results are suggestive of a link between the implemented control strategy of a multi-unit AC system and its performance. Results showed that five out of the six proposed strategies might be chosen, depending on the adopted trade-off policy between the comfort level and the system energy demand. In this way, the numerical approach introduced here, along with the combination of the presented findings, provides good support for the decision-making on thermal management inside the cabin, based on the energy consumption and the thermal comfort level.

In the UK local authorities are being incentivized to purchase low emission vehicles through schemes such as the Ultra Low Emissions Bus (ULEB) scheme. To qualify vehicles must prove they meet certain emissions limits over a pre-described drive cycle. One of the key factors that will impact vehicle performance is the operation of the Heating Ventilation and Air Conditioning (HVAC) system, a large consumer of energy in the system, thus it is vital to have an understanding of the thermal behavior of the cabin and HVAC loads required to maintain comfortable conditions. This paper outlines a lumped parameter model of a generic city bus for use in determining such loads and assisting in the creation of control strategies to minimize energy consumption. Using steady state analysis it is possible to determine the average power consumption required to maintain an internal cabin temperature over a single MLTB drive cycle. Dynamic analysis shows that by changing the HVAC strategy it is possible to reduce the energy consumption by removing the need to operate the system at full power for the entire duration of the cycle. By implementing a hysteresis based control strategy that over heats the environment then switches to a low power mode to allow the temperature to recover the model was able to demonstrate potential energy savings of up to 26.6% when compared to the baseline case operating at a constant steady power output.

A dynamic model was adopted to analyze the impact of the occupancy level in a generic bus on the air conditioning (AC) performance, under different control strategies. The dynamic model was built up by coupling two sub-models of an AC system and the cabin, using MATLAB and Simscape toolbox (R2019a). The AC system has two units, which are controlled independently and based on a Vapour Compression Cycle (VCC). The cabin is modelled by means of moisture air networks, exchanging heat with the refrigerant through the evaporator/condenser of the AC units. Five different strategies were investigated for a range of occupancy levels from 5 to 70 people on board. Results show the links between the occupancy level, power, and discomfort level with the implemented control strategies. As the results suggest, adopting a multi-unit AC system would be more advantageous than using a single unit in terms of the discomfort level and power requirement.

The bus sector is currently lagging behind when it comes to implementing autonomous systems for improved vehicle safety. However, in cities such as London, public transport strategies are changing, with requirements being made for advanced driver-assistance systems (ADAS) on buses. This study discusses the adoption of ADAS systems within the bus sector. A review of the on-road ADAS bus trials shows that passive forward collision warning (FCW) and intelligent speed assistance (ISA) systems have been successful in reducing the number of imminent pedestrian/vehicle collision events and improving speed limit compliance, respectively. Bus accident statistics for Great Britain have shown that pedestrians account for 82% of all fatalities, with three quarters occurring with frontal bus impacts. These statistics suggest that the bus forward collision warning system is a priority for inclusion in future vehicles to enhance the driver’s direct vision, and to increase reaction time for earlier brake application. Almost 80% of bus occupant casualties occurred in non-impact situations, mainly during acceleration/deceleration events. Therefore, care must be taken in implementing autonomous braking in buses, to ensure that it does not cause an increased number of deceleration events beyond the safe stability limits for passengers. Real on-road drive cycle data has shown that while instances of unsafe braking events do not occur regularly, there are instances of braking events that would present a hazard to both seated and standing passengers, therefore systems that would mitigate these issues would have real benefits to both passenger comfort and safety. During tests to simulate the use of the vehicle retarder for an autonomous braking system, deceleration rates largely remained safely within standee and seated passenger stability limits, whereas an emergency stop test showed a peak deceleration 3.5 times the limit of a standee supported by a vertical handrail, and 4 times the limit for a forward/backward facing seated passenger.

With increasing numbers of students from culturally and linguistically diverse backgrounds enrolling in English for Academic Purposes (EAP) programs, understanding intercultural communicative competence can contribute to developing effective EAP pathways to higher education. This review of the literature was carried out to synthesize and uncover emerging themes related to intercultural communicative competence and EAP over a 20-year period from 1996 to 2016. A careful search found 15 scholarly works related to this topic. Papers were coded and analyzed for their key findings to reveal eight major themes: miscommunication, ethnocentrism, acculturation, awareness, ethnorelativism, identity, teaching and learning, and academic success. The scant literature related to the topic points to the need for further research. However, the findings do indicate how EAP practitioners can move away from ethnocentric perceptions and programs of study fixed on acculturation toward ethnorelative understandings and EAP classrooms that support intercultural awareness for both teachers and students., Il y a un nombre croissant d’étudiants d’origines culturelles et linguistiques diverses dans les programmes d’anglais à des fins académiques (PAFA). Par conséquent, la compréhension des compétences en communication interculturelle peut contribuer à développer les voies d’accès efficaces au PAFA vers les études post-secondaires. Cette recension des écrits a été réalisée pour synthétiser et découvrir les thèmes émergents liés à la compétence en communication interculturelle et au PAFA pendant une période de 20 ans, de 1996 à 2016. Notre recherche a trouvé 15 articles liés à ce sujet. Les articles ont été codés et analysés pour leurs résultats clés afin de révéler huit thèmes principaux : mauvaise communication, ethnocentrisme, acculturation, sensibilisation, ethnorelativisme, identité, enseignement et apprentissage, et réussite scolaire. Les écrits scientifiques limités liés au sujet font ressortir le besoin de recherches supplémentaires. Cependant, les résultats ont indiqué les façons dont les praticiens du PAFA pouvaient s’éloigner des perceptions ethnocentriques et des programmes d’études axés sur l’acculturation vers des compréhensions ethnorelatives et des salles de classe du PAFA qui favorisent la sensibilisation interculturelle des enseignants et des élèves.

Generally, >40% of the useful energy (cooling engine and exhaust gases) are wasted by a biogas power plant through the cooling radiator and the exhaust gases. An efficient way to convert this waste heat into work and eventually electricity is the use of an organic Rankine cycle (ORC) power system. Over the last few years, different architectures have been widely investigated (subcritical, wet expansion and trans-critical). Despite the promising performances, realistic economic and technical constraints, also related to the application, are required for a meaningful comparison between ORC technologies and architectures. Starting from the limited literature available, the aim of the present paper is to provide a methodology to compare sub-critical, trans-critical and wet expansion cycles and different types of expanders (both volumetric and turbomachinery) from both technical and economic point of view, which represent one of the main novel aspects of the present work. In particular, the paper focuses on the thermo-economic optimization of an ORC waste heat recovery unit for a 500 kWe biogas power plant located in a detailed regional market, which was not investigated yet. By means of a genetic algorithm, the adopted methodology optimizes a given economic criteria (Pay-Back Period, Net Present Value, Profitability Index and Internal Rate of Return) while respecting technical constraints (expander limitations) and thermodynamic constraints (positive pinch points in heat exchangers, etc.). The results show that optimal ORC solutions with a potential of energy savings up to 600 MWh a year and with a pay-back period lower than 3 years are achievable in the regional market analysed.

This study investigates the application of a circular economy in a rural agricultural setting in Northern Ireland, centered around a typical anaerobic digestion (AD) plant, showing its potential to provide renewable energy for the electricity and transport fuel needs of an average dairy farm and associated milk processing facilities. It was calculated that a typical AD plant has the potential to fuel 22 average sized dairy farms in Northern Ireland, equating to the production, transport, and processing of 51,986 litres of milk per day. The feedstock needs of the AD plant can be provided by the local farming community.

While service learning platforms hold great potential for adult learners of English as an additional language (EAL), there has been little research to date related to the impact of these programs on adult newcomers’ linguistic and social development. The Multicultural Café was a food service learning platform for adult EAL learners operated over a 7-month period at a regional college in the British Columbia interior. The café was developed to provide adult immigrant learners of EAL with an opportunity to authentically engage in using English to provide a valued service to the local community. The current study was conducted to explore the impact of the service learning experience from the perspective of the participants. Using a qualitative case study research design, data were gathered from participants (n = 10) through a questionnaire, semistructured interviews, and a focus group. Data were transcribed, coded, and collected into emerging themes. Opportunities for authentic interactions with customers and with other volunteer coworkers emerged as two of the primary outcomes of the service learning experience. Incorporating the service learning opportunity of the Multicultural Café into the participants’ English language learning experiences appeared to enhance their interactions within the college community. Les cadres d’apprentissage par le service communautaire sont très prome eurs pour les apprenants adultes d’anglais langue additionnel (ALA); pourtant, peu de recherche a porté sur l’impact de ces programmes sur le développement linguistique et social des nouveaux arrivants d’âge adulte. Le Café Multiculturel a constitué, pendant une période de 7 mois, un milieu d’apprentissage par le service pour des apprenants adultes d’ALA dans un collège régional de l’intérieur de la Colombie-Britannique. Le café a été développé pour fournir aux immigrants adultes apprenant l’ALA l’occasion de communiquer authentiquement en anglais tout en offrant un service important à la communauté locale. La présente étude a porté sur l’impact de l’expérience d’apprentissage par le service selon la perspective des participants. Employant un plan de recherche qualitative visant une étude de cas, nous avons recueilli des données de participants (n = 10) par le biais d’un questionnaire, d’entrevues semi-structurées et d’un groupe de discussion. Les données ont été transcrites, codées et rassemblées selon des thèmes qui s’y dégageaient. Deux des résultats principaux de l’expérience de l’apprentissage par le service consistaient en les occasions d’interactions authentiques avec les clients et avec les autres collègues bénévoles. L’intégration, dans le parcours pédagogique des apprenants d’anglais, de l’expérience de l’apprentissage par le service au Café Multiculturel semble avoir mis en valeur leurs interactions au sein de la communauté du collège.

Simulation is a well-established and effective approach to the development of fuel-efficient and low-emissions vehicles in both on-highway and off-highway applications. The simulation of on-highway automotive vehicles is widely reported in literature, whereas research relating to non-automotive and off-highway vehicles is relatively sparse. This review paper focuses on the challenges of simulating such vehicles and discusses the differences in the approach to drive cycle testing and experimental validation of vehicle simulations. In particular, an inner-city diesel-electric hybrid bus and an ICE (Internal Combustion Engine) powered forklift truck will be used as case studies. Computer prediction of fuel consumption and emissions of automotive vehicles on standardised drive cycles is well-established and commercial software packages such as AVL CRUISE have been specifically developed for this purpose. The vehicles considered in this review paper present new challenges from both the simulation and drive-cycle testing perspectives. For example, in the case of the forklift truck, the drive cycles involve reversing elements, variable mass, lifting operations, and do not specify a precise velocity-time profile. In particular, the difficulties associated with the prediction of productivity, i.e. the maximum rate of completing a series of defined operations, are discussed. In the case of the hybrid bus, the standardised drive cycles are unrepresentative of real-life use and alternative approaches are required in the development of efficient and low-emission vehicles. Two simulation approaches are reviewed: the adaptation of a standard automotive vehicle simulation package, and the development of bespoke models using packages such as MATLAB/Simulink.

An experiment is conducted in this paper to analyse the effect of short cycling phenomenon on the performance of a hybrid photovoltaic-thermal heat pump system. The system utilises indirect expansion to cool a photovoltaic-thermal panel through a photovoltaic-thermal water buffer tank that supplies a heat pump, providing space heating using a convection radiator. A photovoltaic-thermal module rated at 200 W electrically and 650 W thermally is generates electricity and absorbs heat to be utilized by a water-to-water heat pump with heating capacity of 7.77 kW. The system was monitored over one-hour operating times for a range of solar irradiances [250 W/m2-650 W/m2], water flow rates through the photovoltaic-thermal module [7.3 l/min – 17.3 l/min] and photovoltaic-thermal buffer tank water volumes [45 litres – 75 litres]. Results show the system successfully cools the photovoltaic surface by up to 33oC. This leads to an electrical efficiency increase of up to 0.7%, correlating to a 17.5% increase in generated electricity. The heat pump experiences coefficient of performance values up to 7. Short cycling frequency increased as the solar irradiance increased. Varying water flow rates through the photovoltaic-thermal module have less influence on system performance than solar irradiance, however, increasing the flow rate from 7.3 l/min to 17.3 l/min results in the photovoltaic surface temperature reducing by 1oC and short cycling frequency increasing. Variation in the photovoltaic-thermal buffer tank water volume from 45 to 75 litres decreased the photovoltaic surface temperature by 5oC and increased the short cycling frequency from 6 cycles/hour to 3 cycles/hour.

This paper presents the analysis and results of a supercritical WHR (Waste Heat Recovery) ORC (Organic Rankine Cycle) modelling study. The study focuses on multiple series heat sources from vehicles and the potential of WHR ORC's to convert this into useful work. The work presented is generally applicable to any waste heat recovery system, either stationary or mobile and, with careful consideration, is also applicable to single heat sources. The simulation model simultaneously calculates WHR ORC performance for multiple circuit layouts related to the position of the regenerator. The work presented details the optimisation of WHR ORC performance with regard to fluid selection from a distinct pool of preselected fluids and from an operational parameter perspective at realistic drive cycle related heat boundary conditions. The paper also looks at WHR ORC performance with regard to condenser pressure and atmospheric conditions for different fluids. The paper concludes with estimated WHR ORC vehicle fuel consumption improvement figures.

This paper presents the rational for the selection of fluids for use in a model based study of sub and supercritical Waste Heat Recovery (WHR) Organic Rankine Cycle (ORC). The study focuses on multiple vehicle heat sources and the potential of WHR ORC’s for its conversion into useful work. The work presented on fluid selection is generally applicable to any waste heat recovery system, either stationary or mobile and, with careful consideration, is also applicable to single heat sources. The fluid selection process presented reduces the number of potential fluids from over one hundred to a group of under twenty fluids for further refinement in a model based WHR ORC performance study. The selection process uses engineering judgement, legislation and, where applicable, health and safety as fluid selection or de-selection criteria. This paper also investigates and discusses the properties of specific ORC fluids with regard to their impact on the theoretical potential for delivering efficient WHR ORC work output. The paper concludes by looking at potential temperature and pressure WHR ORC limits with regard to fluid properties thereby assisting with the generation of WHR ORC simulation boundary conditions.

In this paper a dynamic, modular, 1-D vehicle model architecture is presented that seeks to improve modelling flexibility and can be rapidly adapted to new vehicle concepts, including hybrid vehicles. Interdependencies between model sub-systems are minimized to improve model flexibility. Each subsystem of the vehicle model follows a standardized signal architecture allowing subsystems to be developed, tested and validated separately from the main model and easily re-integrated. Standard dynamic equations are used to calculate the rotational speed of the desired driveline component within each subsystem i.e. dynamic calculations are carried out with respect to the component of interest. Sample simulations are presented for isolated and integrated components to demonstrate flexibility. Two vehicle test cases are presented. The application to a conventional heavy-duty vehicle demonstrates the operational capabilities of the modelling methodology, while the inclusion of electrical components to form a mild-hybrid heavy-duty vehicle shows the model’s potential for predicting improvements in fuel economy and performance over a specified drive cycle. Qualitative validation of the approach is presented, highlighting the ability of the model to accurately capture dynamic events and fuel consumption profiles.

This paper investigates the impacts of offshore wind power forecast error on the operation and management of a pool-based electricity market in 2050. The impact from offshore wind power forecast errors of up to 2000 MW on system generation costs, emission costs, dispatch-down of wind, number of start-ups and system marginal price are analysed. The main findings of this research are an increase in system marginal prices of approximately 1% for every percentage point rise in the offshore wind power forecast error regardless of the average forecast error sign. If offshore wind power generates less than forecasted (−13%) generation costs and system marginal prices increases by 10%. However, if offshore wind power generates more than forecasted (4%) the generation costs decrease yet the system marginal prices increase by 3%. The dispatch down of large quantities of wind power highlights the need for flexible interconnector capacity. From a system operator's perspective it is more beneficial when scheduling wind ahead of the trading period to forecast less wind than will be generated.

This paper reports the detailed description and validation of a fully automated, computer controlled analytical method to spatially probe the gas composition and thermal characteristics in packed bed systems. This method has been designed to limit the invasiveness of the probe, a characteristic assessed using CFD. The thermocouple is aligned with the sampling holes to enable simultaneous recording of the gas composition and temperature profiles. This analysis technique has been validated by studying CO oxidation over a 1% Pt/Al2O3 catalyst. The resultant profiles have been compared with a micro-kinetic model, to further assess the strength of the technique.

This paper presents the background rationale and key findings for a model-based study of supercritical waste heat recovery organic Rankine cycles. The paper’s objective is to cover the necessary groundwork to facilitate the future operation of a thermodynamic organic Rankine cycle model under realistic thermodynamic boundary conditions for performance optimisation of organic Rankine cycles. This involves determining the type of power cycle for organic Rankine cycles, the circuit configuration and suitable boundary conditions. The study focuses on multiple heat sources from vehicles but the findings are generally applicable, with careful consideration, to any waste heat recovery system. This paper introduces waste heat recovery and discusses the general merits of organic fluids versus water and supercritical operation versus subcritical operation from a theoretical perspective and, where possible, from a practical perspective. The benefits of regeneration are investigated from an efficiency perspective for selected subcritical and supercritical conditions. A simulation model is described with an introduction to some general Rankine cycle boundary conditions. The paper describes the analysis of real hybrid vehicle data from several driving cycles and its manipulation to represent the thermal inertia for model heat input boundary conditions. Basic theory suggests that selecting the operating pressures and temperatures to maximise the Rankine cycle performance is relatively straightforward. However, it was found that this may not be the case for an organic Rankine cycle operating in a vehicle. When operating in a driving cycle, the available heat and its quality can vary with the power output and between heat sources. For example, the available coolant heat does not vary much with the load, whereas the quantity and quality of the exhaust heat varies considerably. The key objective for operation in the vehicle is optimum utilisation of the available heat by delivering the maximum work out. The fluid selection process and the presentation and analysis of the final results of the simulation work on organic Rankine cycles are the subjects of two future publications.

There is considerable disagreement in the literature on available oxygen storage capacity, and on the reaction rates associated with the storage process, for three-way automotive catalysts. This paper seeks to address the issue of oxygen storage capacity in a clear and precise manner. The work described involved a detailed investigation of oxygen storage capacity in typical samples of automotive catalysts. The capacity has also been precisely defined and estimates have been made of the specific capacity based on catalyst dimensions. A purpose-built miniature catalyst test rig has been assembled to allow measurement of the capacity and the experimental procedure has been developed to ensure accurate measurement. The measurements from the first series of experiments have been compared with the theoretical calculations and good agreement is seen. A second series of experiments allowed the e ect of temperature on oxygen storage capacity to be investigated. This work shows very clearly the large variation of the capacity with temperature.

Hybrid vehicles can use energy storage systems to disconnect the engine from the driving wheels of the vehicle. This enables the engine to be run closer to its optimum operating condition, but fuel energy is still wasted through the exhaust system as heat. The use of a turbogenerator on the exhaust line addresses this problem by capturing some of the otherwise wasted heat and converting it into useful electrical energy.This paper outlines the work undertaken to model the engine of a diesel-electric hybrid bus, coupled with a hybrid powertrain model which analysed the performance of a hybrid vehicle over a drive-cycle. The distribution of the turbogenerator power was analysed along with the effect on the fuel consumption of the bus. This showed that including the turbogenerator produced a 2.4% reduction in fuel consumption over a typical drive-cycle.The hybrid bus generator was then optimised to improve the performance of the combined vehicle/engine package and the turbogenerator was then shown to offer a 3.0% reduction in fuel consumption. The financial benefits of using the turbogenerator were also considered in terms of fuel savings for operators. For an average bus, a turbogenerator could reduce fuel costs by around £1200 per year.

This paper describes the development of a two-dimensional transient catalyst model. Although designed primarily for two-stroke direct injection engines, the model is also applicable to four-stroke lean burn and diesel applications. The first section describes the geometries, properties and chemical processes simulated by the model and discusses the limitations and assumptions applied. A review of the modelling techniques adopted by other researchers is also included. The mathematical relationships which are used to represent the system are then described, together with the finite volume method used in the computer program. The need for a two-dimensional approach is explained and the methods used to model effects such as flow and temperature distribution are presented. The problems associated with developing surface reaction rates are discussed in detail and compared with published research. Validation and calibration of the model are achieved by comparing predictions with measurements from a flow reactor. While an extensive validation process, involving detailed measurements of gas composition and thermal gradients, has been completed, the analysis is too detailed for publication here and is the subject of a separate technical paper

The fuel consumption of automotive vehicles has become a prime consideration to manufacturers and operators as fuel prices continue to rise steadily, and legislation governing toxic emissions becomes ever more strict. This is particularly true for bus operators as government fuel subsidies are cut or removed. In an effort to reduce the fuel consumption of a diesel-electric hybrid bus, an exhaust recovery turbogenerator has been selected from a wide ranging literature review as the most appropriate method of recovering some of the wasted heat in the exhaust line. This paper examines the effect on fuel consumption of a turbogenerator applied to a 2.4-litre diesel engine. A validated one-dimensional engine model created using Ricardo WAVE was used as a baseline, and was modified in subsequent models to include a turbogenerator downstream, and in series with, the turbocharger turbine. A fuel consumption map of the modified engine was produced, and an in-house simulation tool was then used to examine the fuel economy benefit delivered by the turbogenerator on a bus operating on various drive-cycles. A parametric study is presented which examined the performance of turbogenerators of various size and power output. The operating strategy of the turbogenerator was also discussed with a view to maximising turbine efficiency at each operating point. The performance of the existing turbocharger on the hybrid bus was also investigated; both the compressor and turbine were optimised and the subsequent benefits to the fuel consumption of the vehicle were shown. The final configuration is then presented and the overall improvement in fuel economy of the hybrid bus was determined over various drive-cycles.

Modern internal combustion (IC) engines reject around two thirds of the energy provided by the fuel as low-grade waste heat. Capturing a portion of this waste heat energy and transforming it into a more useful form of energy could result in a significant reduction in fuel consumption. By using the low-grade heat, an organic Rankine cycle (ORC) can produce mechanical work from a pressurised organic fluid with the use of an expander.

This paper investigates the modelling of a waste heat recovery system on a hybrid bus to supplement the air conditioning system. Research indicates that while a vehicle is idling or in a traffic jam, the air conditioning compressor can consume between 9 to 44% of the engine’s power. At present in a modern compression ignition engine the efficiency can be as high as 40% while operating under ideal conditions, however this can drop dramatically depending on road and load conditions. With such a large portion of fuel energy being rejected as waste heat, developing a WHR system to supplement the air conditioning system is seen as a worthwhile proposition. Reducing the power consumption of the air conditioning system will allow a reduction in fuel consumption and engine emissions.

The findings by Muehlenbachs et al. [1] that placental malaria (PM) is associated with hypertension in first-time mothers aged 18–20 years is significant, and not to be explained at this time of writing. The authors also provide data suggesting that the maternal–fetal conflict, during chronic PM and hypertension in first-time mothers, involves the VEGF pathway. Previously [2–5], I have posited that prolactin might have a role in PM and these new findings might provide further indirect evidence for such a role. It should be remembered that there is an extensive and decades-old literature (see Horrobin's chapter 23 in [6]) on the role of prolactin in hypertension; and more specifically, the relationship between prolactin and pregnancy-related hypertension [7,8]. Regarding the VEGF pathway, Malaguarnera et al. [9] have recently shown that prolactin induces VEGF production in human macrophages. It is conceivable that hyperprolactinemia (pituitary and/or placental) could up-regulate placental macrophage production of VEGF. Space does not permit a discussion of the well known fact of increased pregnancy-related prolactin in first-time mothers, but this has been noted elsewhere [2] concerning maternal malaria. Although there has been controversy of late [2,10], regarding my “prolactin hypothesis” in maternal malaria, it is time definitive experiments be conducted to ascertain if prolactin is playing a role in PM, and in other infectious diseases as well.

The incorporation of one-dimensional simulation codes within engine modelling applications has proved to be a useful tool in evaluating unsteady gas flow through elements in the exhaust system. This paper reports on an experimental and theoretical investigation into the behaviour of unsteady gas flow through catalyst substrate elements. A one-dimensional (1-D) catalyst model has been incorporated into a 1 -D simulation code to predict this behaviour. Experimental data was acquired using a 'single pulse' test rig. Substrate samples were tested under ambient conditions in order to investigate a range of regimes experienced by the catalyst during operation. This allowed reflection and transmission characteristics to be quantified in relation to both geometric and physical properties of substrate elements. Correlation between measured and predicted results is demonstrably good and the model provides an effective analysis tool for evaluating unsteady gas flow through different catalytic converter designs.

Due to stringent emissions legislation, the use of three way catalysts is becoming increasingly prevalent in motorcycles and scooters. This paper describes the development, and subsequent validation, of a detailed mathematical model for the oxygen storage processes in three-way catalysts. The model consists of several interdependent sub-models describing the oxidation and reduction processes and their interaction with a kinetic model of the catalyst. The structure and equations of the model are detailed and their significance discussed. For the validation phase of the work a purpose-built miniature catalyst test rig has been assembled and a series of experiments conducted to assess the oxygen storage processes. Analysis of this data also provided values for the controlling constants associated with the oxidation and reduction reactions. These results are included and compared with other published data. The analytical results from the experimental work have been used to provide the model with the important kinetic control factors, which are not readily available from literature. Finally, the experimental results are compared with the model predictions and good agreement is shown.

This paper details a theoretical and experimental study of combustion phenomena within a two-stroke-cycle, spark ignition engine. The theoretical part of the work involved the development of an improved quasi-dimensional combustion model. This model was incorporated into a computer program which was used to predict the thermodynamic and chemical changes occurring within a two-stroke engine during the closed cycle of the engine. The simulation uses a turbulent kinetic energy model to predict flame front velocity. Combustion chamber geometry is used to estimate entrained mass, and mass fraction burned is calculated from a simple eddy-entrainment approach. The experimental work was undertaken to validate the combustion model. Two separate cylinder heads were designed with different combustion chambers and tested on a standard loop-scavenged engine over a range of operating conditions. This validation showed good correlation between measured and predicted results, but the differences seen highlight some areas requiring further consideration. It is postulated that the main influencing factors are squish effects and cycle-to-cycle variation. 23 refs., 12 figs., 3 tabs.

Menendez, et al.1xMalaria-related anaemia. Menendez, C. et al. Parasitol. Today. 2000; 16: 469–476Abstract | Full Text | Full Text PDF | PubMed | Scopus (180)See all References1 have judiciously reviewed our understanding of malaria-related anaemia, especially the anaemia related to falciparum infection in pregnant women. In addition, I would point to the findings of Diagne et al.2xIncreased suceptibility to malaria during the early postpartum period. Diagne, N. et al. New Eng. J. Med. 2000; 343: 598–603CrossRef | PubMed | Scopus (94)See all References2, which provide corollary evidence of an interesting connection between maternal malaria and anaemia. They report that pregnant women are most susceptible to malaria in their second and third trimester and up to 60 days postpartum.Here, I wish to remind the reader that from the second trimester through to the postpartum period (lactation), increased pulsatile levels of prolactin are observed. Remarkably, searching MEDLINE and Web of Science reveals only one brief mention of prolactin in all the literature on malaria 3xStudies on the nature of thyroidal suppression during acute falciparum malaria: integrity of pituitary response to TRH and alterations in serum T3 and reverse T3. Wartofsky, L. et al. J. Clin. Endocrinol. Metab. 1977; 44: 85–89CrossRef | PubMedSee all References3.As reviewed by Menendez et al.1xMalaria-related anaemia. Menendez, C. et al. Parasitol. Today. 2000; 16: 469–476Abstract | Full Text | Full Text PDF | PubMed | Scopus (180)See all References1, both nitric oxide (NO) and tumour necrosis factor (TNF) are elevated in severe malaria, whereas erythropoeitin (EPO) is suppressed. This is exactly what we should expect if elevated prolactin were involved in the pathology, because prolactin has been shown to have a stimulatory effect on both NO and TNF production in rats 4xProlactin modulation of nitric oxide and TNF production by peripheral neutrophils in rats. Meli, R. et al. Life Sci. 1997; 61: 1395–1403CrossRef | PubMed | Scopus (29)See all References4, and hyperprolactinemia is associated with depressed EPO production 5xAssociation between elevated prolactin levels and circulating erythroid precursors in dialyzed patients. Bellone, G. et al. Proc. Soc. Exp. Biol. Med. 2000; 223: 367–371CrossRef | PubMedSee all References5. Moreover, it should be noted that EPO and prolactin have been studied extensively in dialysis patients suffering from anaemia. This raises the possibility that prolactin is the missing piece of the puzzle in both maternal malaria and in the severe anaemia witnessed in falciparum malaria. This hypothesis is eminently testable, and doing so would appear highly warranted.

An investigation is reported into the error rate of the indirect antiglobulin test when random, weakly reactive samples are tested. Tests were completed by the majority of laboratory staff in 2 transfusion services and 3 major general hospital blood banks, during their routine daily work. A significant level of technical difficulty was revealed, from 5.2 to 60.8% of positive tests being called negative, and from 5.7 to 32.3% of negative tests being called positive. Reproducibility of weakly reacting duplicates was generally poor, as was the allocation of score values to the agglutination reactions. The significance of these findings relative to the content of quality control surveys is discussed.

The LSU reciprocation-gait orthosis is a lightweight bracing device that gives structural support to the lower trunk and lower limbs of the paralytic patient while allowing, through a cable-coupling system, proper hip joint motion for walking.

Surgical procedures for myelodysplastic patients being prepared for treatment with the LSU reciprocation-gait system should correct any contractures or deformities of the lower extremities that are severe enough to prevent brace fitting. Most of these procedures should be done when the patient is between six and nine months, to enable the lower extremities to be in braceable position by the age of nine to twelve months.

Seventeen patients with myelomeningocele were fitted with a device that reciprocally controls hip flexion and extension in an attempt to improve ambulatory ability. To evaluate the function of the reciprocating mechanism, the orthosis was tested in three configurations. With the reciprocating mechanism functioning at the hips, five of eight patients ambulated faster than in other configurations. With the mechanism released for free hip joint motion, five of eight patients ambulated slower or not at all. With the hip joints locked, six of eight patients ambulated more slowly than with the reciprocating mechanism functioning. Two were faster with a swing-through gait. However, 11 of 12 independent ambulators spontaneously chose the reciprocating gait pattern over the swing-through pattern. The reciprocating gait orthosis was used by patients with meningomyelocele from 18 months to 15 years of age. The device was most successful if strong hip flexors were present, although ambulation in a reciprocal pattern was possible for some with no active hip musculature. We believe that this orthosis is the most effective ambulatory aid for children handicapped by hip extensor weakness.