7,321 research outputs found
Hybrid energy sources for electric and fuel cell vehicle propulsion
Given the energy (and hence range) and performance limitations of electro-chemical batteries, hybrid systems combining energy and power dense storage technologies have been proposed for electric vehicle propulsion. The paper will discuss the application of electro-chemical batteries, supercapacitors and fuel cells in single and hybrid source configurations for electric vehicle drive-train applications. Simulation models of energy sources are presented and used to investigate the design optimisation of electric vehicle on-board energy source in terms of energy efficiency and storage mass/volume. Results from a case study considering a typical small urban electric vehicle are presented, illustrating the benefits of hybrid energy sources in terms of system mass and vehicle range. The models and approach can be applied to other vehicles and driving regimes
A H2 PEM fuel cell and high energy dense battery hybrid energy source for an urban electric vehicle
Electric vehicles are set to play a prominent role in addressing the energy and environmental impact of an increasing road transport population by offering a more energy efficient and less polluting drive-train alternative to conventional internal combustion engine (ICE) vehicles. Given the energy (and hence range) and performance limitations of electro-chemical battery storage systems, hybrid systems combining energy and power dense storage technologies have been proposed for vehicle applications. The paper discusses the application of a hydrogen fuel cell as a range extender for an urban electric vehicle for which the primary energy source is provided by a high energy dense battery. A review of fuel cell systems and automotive drive-train application issues are discussed, together with an overview of the battery technology. The prototype fuel cell and battery component simulation models are presented and their performance as a combined energy/power source assessed for typical urban and sub-urban driving scenario
Finding relationships between effort and other variables in the SEL
Estimating the amount of effort required for a software development project is one of the major aspects of resource estimation for that project. In this study, the relationship between effort and other variables for 23 Software Engineering Laboratory (SEL) projects that were developed for NASA/Goddard Space Flight Center was examined. These variables fell into two categories: those which can be determined in the early stages of project development and may therefore be useful in a baseline equation for predicting effort in future projects, and those which can be used mainly to characterize or evaluate effort requirements and thus enhance the understanding of the software development process in this environment. Some results of the analyses are presented
Algorithms for optimal control of stochastic switching systems
© 2016 Society for Industrial and Applied Mathematics. Optimal control problems of switching type with linear state dynamics are ubiquitous in applications of stochastic optimization. For high-dimensional problems of this type, solutions which utilize some convexity related properties are useful. For such problems, we present novel algorithmic solutions which require minimal assumptions while demonstrating remarkable computational efficiency. Furthermore, we devise procedures of the primal-dual kind to assess the distance to optimality of these approximate solutions
Recommended from our members
Understanding the fundamentals of freight markets volatility
We analyse empirically the drivers of freight market volatility. We use several macroeconomic and shipping-related factors that are known to affect the supply and demand for shipping and examine their impact on the term structure of freight options implied volatilities (IV). We find that the level of IVs is affected by the level of the spot rate, the slope of the forward curve, as well as by both demand and supply factors, especially the former. We demonstrate that the relation between the volatility of futures prices and the slope of the forward curve is non-monotonic and convex, that is, it has a V-shape. In general, anticipation of economic growth and of a stronger freight market reduces IV whereas higher uncertainty and anticipation of excess shipping capacity may increase IV. Panel regressions as well as a series of robustness tests produce strong validation of the results
Frequencies of the Transferrin Alleles and Genotypes in Crossbred Cattle and their Effect on Growth Traits
Records on birth weight, body 'weight and body measurement traits were obtained from a total of 149
crossbred animals (Zebu X Temperate) from the lnstitut Haiwan Kluang, From the blood samples collected
from these animals, 14.5 of them were analysed for the presence of serum transferrin genotypes.
Frequency of the TID gene was found to be highest in both the half bred and quarter-bred Zebus, Frequency
of lyA and lyE was found to be lower and higher respectively in half-bred Zebus and the quarter-bred
Zebus.
In general, there were no significant variations (P < a.OS) between the effects of different transferrin
genotypes observed (TfAA, Tf:1D, 7y/n, l/DD alld 1/D1\) on any of the body weight or body conformation trait
Patterns of care and emergency presentations for people with non-small cell lung cancer in New South Wales, Australia: A population-based study
Introduction Little is known about population-wide emergency presentations and patterns of care for people diagnosed with non-small cell lung cancer (NSCLC) in Australia. We examined patients’ characteristics associated with presenting to an emergency department around the time of diagnosis (“emergency presenters”), and receiving anti-cancer treatment within 12 months of diagnosis. Materials and Methods Participants in the 45 and Up Study who were newly diagnosed with NSCLC during 2006–2010 were included. We used linked data from population-wide health databases including Medicare and pharmaceutical claims, inpatient hospitalisations and emergency department presentations to follow participants to June 2014. Patients’ characteristics associated with being an emergency presenter and receiving any anti-cancer treatment were examined. Results A total of 647 NSCLC cases were included (58.6% male, median age 73 years). Emergency presenters (34.5% of cases) were more likely to have a high Charlson comorbidity index score, be an ex-smoker who had quit in the past 15 years and to be diagnosed with distant metastases. Almost all patients had visited their general practitioner ≥3 times in the 6 months prior to diagnosis. Nearly one-third (29.5%) of patients did not receive any anti-cancer treatment, however, there were no differences between emergency and non-emergency presenters in the likelihood of receiving treatment. Those less likely to be treated were older, had no private health insurance, and had unknown stage disease recorded. Conclusion Our results indicate the difficulties in diagnosing lung cancer at an early stage and inequities in NSCLC treatment. Future research should address opportunities to diagnose lung cancer earlier and to optimise treatment pathways
Assessing the marginal dollar value losses to an estuarine ecosystem from an aggressive alien invasive crab
This paper reports on a case study to establish dollar values for loss of
biodiversity in the New Zealand coastal marine environment. The study uses
the European Shore Crab (Carcinas maenas) as the example alien invasive
species and the Pauatahanui Inlet, Wellington, New Zealand, as the
ecosystem representative of the coastal marine environment. Choice modelling is the stated preference tool used to elicit marginal dollar values for these various attributes of the inlet. Reallocation of existing government expenditure is used as the payment mechanism. Results indicate a wide range of dollar values for the marginal losses to the environment, with no clear trend on a distance-decay relationship. The probability distributions of the dollar values of the environmental attributes tended to have a concentration around the median with very wide tails, especially on the high side. This indicates that most people generally agreed on a dollar value, but a very few individuals expressed extremely high values. The study concludes
that the dollar values for loss of biodiversity and other environmental
attributes do provide useful information to decision makers, but considerable caution needs to be exercised when applying these values in benefit cost studies. Marginal rate of substitution estimates between environmental attributes will be useful for estimating money values for attributes identified given future work estimates a statistically significant money value for one
Outbreak of acute hepatitis C following the use of anti-hepatitis C virus--screened intravenous immunoglobulin therapy
BACKGROUND and AIMS: Hepatitis C virus (HCV) infection has been associated with intravenous (IV) immunoglobulin (Ig), and plasma donations used to prepare IV Ig are now screened to prevent transmission. Thirty-six patients from the United Kingdom received infusions from a batch of anti-HCV antibody-screened intravenous Ig (Gammagard; Baxter Healthcare Ltd., Thetford, Norfolk, England) that was associated with reports of acute hepatitis C outbreak in Europe. The aim of this study was to document the epidemiology of this outbreak. METHODS: Forty-six patients from the United Kingdom treated with Gammagard (34 exposed and 12 unexposed to the batch) returned epidemiological questionnaires. RESULTS: Eighty-two percent of the exposed patients (28 of 34) became positive for HCV RNA. Eighteen percent of the patients (6 of 34) who had infusions with this batch tested negative for HCV RNA, but 2 of the patients had abnormal liver function and subsequently seroconverted to anti-HCV antibody positive. Twenty-seven percent of the patients (9 of 34) developed jaundice, and 79% (27 of 34) had abnormal liver transferase levels. Virus isolates (n=21), including an isolate from the implicated batch, were genotype 1a and virtually identical by sequence analysis of the NS5 region, consistent with transmission from a single source. CONCLUSIONS: Hepatitis C infection can be transmitted by anti-HCV-screened IV Ig. Careful documentation of IV Ig batch numbers and regular biochemical monitoring is recommended for all IV Ig recipients
Professional Competencies and Job Performance of Select Academic Librarians in Laguna, Philippines
Objective. Academic libraries formulate missions, visions, goals, and objectives based on the aims of the parent organization. There are issues with how librarianship is introduced, particularly in post-generation Z, when individuals have misconceptions about the functions of librarians. This study examined the level of professional competencies and job performance of selected academic librarians in the 21st Century. Methods. Descriptive-correlation method of research was used to provide static pictures of situations as well as to establish relationship between different variables. The respondents of this study are selected academic librarians in region IV-A Philippines. Results. Findings revealed that majority of respondents were 31 years old and above and were female. Meanwhile, the majority of the respondents attained their bachelor's degree and had been in the service for 10 years and below. The academic librarians are highly competent in managing information technologies among three domains of professional competencies. The academic librarians achieve very high level of job performance maintaining high quantity of work, fulfilling job duties, consistent for high quality of work, respond to the needs of users, provide accurate resources, demonstrate responsiveness, are able to use technology, and actively participate in forums. The academic librarians aged 31 years old and above, with master's degree and have 11 years and above of service, higher level of professional competencies than their younger counterpart, with bachelor's degree and 10 years and below of service. The higher the respondents' level of professional competencies in all its dimensions, the higher the level of respondent’s job performance. Conclusions. It can be concluded that the majority of academic librarians in this study were female, 31 years old and above. They had a bachelor's degree and 10 years or less of service. Academic librarians showed high competence in managing information technologies and consistently performed well in their job duties. Older librarians with a master's degree and over 11 years of service displayed higher professional competency and job performance compared to younger librarians with a bachelor's degree and less than 10 years of service. There was a positive correlation between professional competencies and job performance. Overall, academic librarians in this study exhibited strong professional competencies and high job performance
- …