280 research outputs found

    Hybrid energy storage system optimal sizing for urban electrical bus regarding battery thermal behavior

    Get PDF
    This paper proposes an algorithm for sizing the hybrid energy storage system of an urban electrical bus regarding battery thermal behavior. The aim of this study is to get the supercapacitors optimal contribution part in the hybrid energy storage system to keep the battery temperature within its allowable limit. A semi-active parallel topology that uses supercapacitors as a main source of energy is considered. According to the bus mechanical parameters and the ARTEMIS driving cycle, the power and energy demand are calculated. Using mathematical models for the battery, supercapacitors and DC-DC converter, several simulations are performed for different hybridization percentages. While observing the evolution of battery temperature, the most favorable hybridization percentage is defined

    A Formalization of The Natural Gradient Method for General Similarity Measures

    Full text link
    In optimization, the natural gradient method is well-known for likelihood maximization. The method uses the Kullback-Leibler divergence, corresponding infinitesimally to the Fisher-Rao metric, which is pulled back to the parameter space of a family of probability distributions. This way, gradients with respect to the parameters respect the Fisher-Rao geometry of the space of distributions, which might differ vastly from the standard Euclidean geometry of the parameter space, often leading to faster convergence. However, when minimizing an arbitrary similarity measure between distributions, it is generally unclear which metric to use. We provide a general framework that, given a similarity measure, derives a metric for the natural gradient. We then discuss connections between the natural gradient method and multiple other optimization techniques in the literature. Finally, we provide computations of the formal natural gradient to show overlap with well-known cases and to compute natural gradients in novel frameworks

    Antibacterial activity of various honey types of Algeria against Staphylococcus aureus and Streptococcus pyogenes

    Get PDF
    AbstractObjectiveTo assess the in vitro antibacterial activity of honey from different geographical location on Gram negative organismes.MethodsDifferent concentrations (Undiluted honey, 10 %, 30%, 50% and 70% wt/vol) of honey were studied in vitro using Staphylococcus aureus (S. aureus) and Streptococcus pyogenes (S. pyogenes), briefly, two-fold dilutions of honey solutions were tested to determine the minimum inhibitory concentration (MIC) against each type of microorganism, followed by more assays within a narrower dilution range to obtain more precise MIC values. MICs were determined by both visual inspection and spectrophotometric assay at 620 nm. These honey samples were compared with standard antibiotics like ampicillin, penicillin G, amoxicillin, gentamycin, tobramycin, erythromycin and chloramphenicol was determined by the disc diffusion method.ResultsThe diameter of zone of the inhibition (ZDI) of honey has various concentrations tested for the isolates ranged 0–46 mm for S. aureus, 0–44 mm for S. pyogenes. While the MIC (%) ranged 12%-95%, 25%-73% respectively.ConclusionsAlgeria honey, in-vitro, possess antibacterial activity

    A harmless evil: giant fungating benign breast mass in an adolescent mimicking malignancy - case report

    Get PDF
    Introduction: Juvenile giant fibroadenoma is a rare type of fibroadenoma characterized by rapid growth of a breast tumor in an adolescent. Benign in nature, they rarely present as fungating and ulcerating tumors. Benign tumors masquerading as malignancies are surgical conundrums. No co nsensus exists yet on the management of these cases. We aim to discuss the dilemma in managing a bleeding, fungating giant fibroadenoma in an adolescent female and highlight risks of alternative therapies. Presentation of case: A 19-year-old lady presented with a bleeding, fungating breast mass worsened with topical herbal concoction. Examination revealed a 10 × 15 cm fungating breast mass that obliterated her nipple- areolar complex (NAC). Computed Tomography (CT) scan reported a huge heterogeneously enhancing mass 10.6 — 14.5 — 15.1 cm with loss of normal fat plane with the overlying skin but a clear fat plane with the pectoralis muscle posteriorly. Discussion: Giant breast masses that fungate and ulcerate usually indicate a sinister pathology. Traditional remedies have been reported to exacerbate growth. In cases where most of the breast parenchyma and NAC has been destroyed, it is no longer possible to proceed with breast conserving techniques. Breast reconstruction is crucial in adolescents and should be tailored to the patient's existing breast size as well as body habitus. Conclusion: In juvenile giant fibroadenomas where breast parenchyma and NAC has been destroyed, breast reconstruction is the goal. The lack of consensus in both diagnosis and management further compounds the difficulty in dealing with this sensitive population. Awareness needs to be raised regarding negative effects related to traditional medicine

    Modulation Techniques for Biomedical Implanted Devices and Their Challenges

    Get PDF
    Implanted medical devices are very important electronic devices because of their usefulness in monitoring and diagnosis, safety and comfort for patients. Since 1950s, remarkable efforts have been undertaken for the development of bio-medical implanted and wireless telemetry bio-devices. Issues such as design of suitable modulation methods, use of power and monitoring devices, transfer energy from external to internal parts with high efficiency and high data rates and low power consumption all play an important role in the development of implantable devices. This paper provides a comprehensive survey on various modulation and demodulation techniques such as amplitude shift keying (ASK), frequency shift keying (FSK) and phase shift keying (PSK) of the existing wireless implanted devices. The details of specifications, including carrier frequency, CMOS size, data rate, power consumption and supply, chip area and application of the various modulation schemes of the implanted devices are investigated and summarized in the tables along with the corresponding key references. Current challenges and problems of the typical modulation applications of these technologies are illustrated with a brief suggestions and discussion for the progress of implanted device research in the future. It is observed that the prime requisites for the good quality of the implanted devices and their reliability are the energy transformation, data rate, CMOS size, power consumption and operation frequency. This review will hopefully lead to increasing efforts towards the development of low powered, high efficient, high data rate and reliable implanted devices

    Pasteurellosis vaccine commercialization: Physiochemical factors for optimum production

    Get PDF
    Pasteurella spp. are Gram-negative facultative bacteria that cause severe economic and animal losses. Pasteurella-based vaccines are the most promising solution for controlling Pasteurella spp. outbreaks. Remarkably, insufficient biomass cultivation (low cell viability and productivity) and lack of knowledge about the cultivation process have impacted the bulk production of animal vaccines. Bioprocess optimization in the shake flask and bioreactor is required to improve process efficiency while lowering production costs. However, its state of the art is limited in providing insights on its biomass upscaling, preventing a cost-effective vaccine with mass-produced bacteria from being developed. In general, in the optimum cultivation of Pasteurella spp., production factors such as pH (6.0–8.2), agitation speed (90–500 rpm), and temperature (35–40 °C) are used to improve production yield. Hence, this review discusses the production strategy of Pasteurella and Mannheimia species that can potentially be used in the vaccines for controlling pasteurellosis. The physicochemical factors related to operational parameter process conditions from a bioprocess engineering perspective that maximize yields with minimized production cost are also covered, with the expectation of facilitating the commercialization process

    An overview of the recent developments on fructooligosaccharide production and applications

    Get PDF
    Over the past years, many researchers have suggested that deficiencies in the diet can lead to disease states and that some diseases can be avoided through an adequate intake of relevant dietary components. Recently, a great interest in dietary modulation of the human gut has been registered. Prebiotics, such as fructooligosaccharides (FOS), play a key role in the improvement of gut microbiota balance and in individual health. FOS are generally used as components of functional foods, are generally regarded as safe (generally recognized as safe status—from the Food and Drug Administration, USA), and worth about 150€ per kilogram. Due to their nutrition- and health-relevant properties, such as moderate sweetness, low carcinogenicity, low calorimetric value, and low glycemic index, FOS have been increasingly used by the food industry. Conventionally, FOS are produced through a two-stage process that requires an enzyme production and purification step in order to proceed with the chemical reaction itself. Several studies have been conducted on the production of FOS, aiming its optimization toward the development of more efficient production processes and their potential as food ingredients. The improvement of FOS yield and productivity can be achieved by the use of different fermentative methods and different microbial sources of FOS producing enzymes and the optimization of nutritional and culture parameter; therefore, this review focuses on the latest progresses in FOS research such as its production, functional properties, and market data.Agencia de Inovacao (AdI)-Project BIOLIFE reference PRIME 03/347. Ana Dominguez acknowledges Fundacao para a Ciencia e a Tecnologia, Portugal, for her PhD grant reference SFRH/BD/23083/2005

    Respiratory Insufficiency Correlated Strongly with Mortality of Rodents Infected with West Nile Virus

    Get PDF
    West Nile virus (WNV) disease can be fatal for high-risk patients. Since WNV or its antigens have been identified in multiple anatomical locations of the central nervous system of persons or rodent models, one cannot know where to investigate the actual mechanism of mortality without careful studies in animal models. In this study, depressed respiratory functions measured by plethysmography correlated strongly with mortality. This respiratory distress, as well as reduced oxygen saturation, occurred beginning as early as 4 days before mortality. Affected medullary respiratory control cells may have contributed to the animals' respiratory insufficiency, because WNV antigen staining was present in neurons located in the ventrolateral medulla. Starvation or dehydration would be irrelevant in people, but could cause death in rodents due to lethargy or loss of appetite. Animal experiments were performed to exclude this possibility. Plasma ketones were increased in moribund infected hamsters, but late-stage starvation markers were not apparent. Moreover, daily subcutaneous administration of 5% dextrose in physiological saline solution did not improve survival or other disease signs. Therefore, infected hamsters did not die from starvation or dehydration. No cerebral edema was apparent in WNV- or sham-infected hamsters as determined by comparing wet-to-total weight ratios of brains, or by evaluating blood-brain-barrier permeability using Evans blue dye penetration into brains. Limited vasculitis was present in the right atrium of the heart of infected hamsters, but abnormal electrocardiograms for several days leading up to mortality did not occur. Since respiratory insufficiency was strongly correlated with mortality more than any other pathological parameter, it is the likely cause of death in rodents. These animal data and a poor prognosis for persons with respiratory insufficiency support the hypothesis that neurological lesions affecting respiratory function may be the primary cause of human WNV-induced death
    • …
    corecore