953 resultados para Vehicle body components.


Relevância:

30.00% 30.00%

Publicador:

Resumo:

In this paper we investigate the first order characteristics of the radio channel between a moving vehicle and a stationary person positioned by the side of a road at 5.8 GHz. The experiments considered a transmitter positioned at different locations on both the body and receivers positioned on the vehicle. The transmitter was alternated between positions on the central chest region, back and the wrist (facing the roadside) of the body, with the receivers placed on the outside roof, the outside rear window and the inside dashboard of the vehicle. The Rice fading model was applied to the measurement data to assess its suitability for characterizing this emerging type of wireless channel. The Ricean K factors calculated from the data suggest that a significant dominant component existed in the majority of the channels considered in this study.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Using device-to-device communications as an underlay for cellular communications will provide an exciting opportunity to increase network capacity as well as improving spectral efficiency. The unique geometry of device-to-device links, where user equipment is often held or carried at low elevation and in close proximity to the human body, will mean that they are particularly susceptible to shadowing events caused not only by the local environment but also by the user's body. In this paper, the shadowed κ - μ fading model is proposed, which is capable of characterizing shadowed fading in wireless communication channels. In this model, the statistics of the received signal are manifested by the clustering of multipath components. Within each of these clusters, a dominant signal component with arbitrary power may exist. The resultant dominant signal component, which is formed by the phasor addition of these leading contributions, is assumed to follow a Nakagami- m distribution. The probability density function, moments, and the moment-generating function are also derived. The new model is then applied to device-to-device links operating at 868 MHz in an outdoor urban environment. It was found that shadowing of the resultant dominant component can vary significantly depending upon the position of the user equipment relative to the body and the link geometry. Overall, the shadowed κ - μ fading model is shown to provide a good fit to the field data as well as providing a useful insight into the characteristics of the received signal.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Highway structures such as bridges are subject to continuous degradation primarily due to ageing, loading and environmental factors. A rational transport policy must monitor and provide adequate maintenance to this infrastructure to guarantee the required levels of transport service and safety. Increasingly in recent years, bridges are being instrumented and monitored on an ongoing basis due to the implementation of Bridge Management Systems. This is very effective and provides a high level of protection to the public and early warning if the bridge becomes unsafe. However, the process can be expensive and time consuming, requiring the installation of sensors and data acquisition electronics on the bridge. This paper investigates the use of an instrumented 2-axle vehicle fitted with accelerometers to monitor the dynamic behaviour of a bridge network in a simple and cost-effective manner. A simplified half car-beam interaction model is used to simulate the passage of a vehicle over a bridge. This investigation involves the frequency domain analysis of the axle accelerations as the vehicle crosses the bridge. The spectrum of the acceleration record contains noise, vehicle, bridge and road frequency components. Therefore, the bridge dynamic behaviour is monitored in simulations for both smooth and rough road surfaces. The vehicle mass and axle spacing are varied in simulations along with bridge structural damping in order to analyse the sensitivity of the vehicle accelerations to a change in bridge properties. These vehicle accelerations can be obtained for different periods of time and serve as a useful tool to monitor the variation of bridge frequency and damping with time.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In this paper we investigate the effects of vehicular traffic on body-to-body (B2B) communications channels in an urban environment at 2.45 GHz. In particular, the impact of differing vehicle types passing in the vicinity of a B2B link are investigated for different body orientations relative to one another at the side of a busy urban street. Initial findings suggest that the average disturbance in a B2B channel can last for 2 seconds and depending on the vehicle size, fades in excess of 40 dB can occur. The body orientations are shown to be a significant factor on the effects of vehicular traffic on the B2B channel.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The food industry is moving towards the use of natural sweeteners such as those produced by Stevia rebaudiana due to the number of health and safety concerns surrounding artificial sweeteners. Despite the fact that these sweeteners are natural; they cannot be assumed safe. Steviol glycosides have a steroidal structure and therefore may have the potential to act as an endocrine disruptor in the body. Reporter gene assays (RGAs), H295R steroidogenesis assay and Ca(2+) fluorimetry based assays using human sperm cells have been used to assess the endocrine disrupting potential of two steviol glycosides: stevioside and rebaudioside A, and their metabolite steviol. A decrease in transcriptional activity of the progestagen receptor was seen following treatment with 25,000 ng/ml steviol in the presence of progesterone (157 ng/ml) resulting in a 31% decrease in progestagen response (p=<0.01). At the level of steroidogenesis, the metabolite steviol (500-25,000 ng/ml) increased progesterone production significantly by 2.3 fold when exposed to 10,000 ng/ml (p=<0.05) and 5 fold when exposed to 25,000 ng/ml (p=<0.001). Additionally, steviol was found to induce an agonistic response on CatSper, a progesterone receptor of sperm, causing a rapid influx of Ca(2+). The response was fully inhibited using a specific CatSper inhibitor. These findings highlight the potential for steviol to act as a potential endocrine disruptor.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This paper investigates the characteristics of the shadowed fading observed in off-body communications channels at 5.8 GHz. This is realized with the aid of the $\kappa-\mu$ / gamma composite fading model which assumes that the transmitted signal undergoes $\kappa-\mu$ fading which is subject to \emph{multiplicative} shadowing. Based on this, the total power of the multipath components, including both the dominant and scattered components, is subject to non-negligible variations that follow the gamma distribution. For this model, we present an integral form of the probability density function (PDF) as well as important analytic expressions for the PDF, cumulative distribution function, moments and moment generating function. In the case of indoor off-body communications, the corresponding measurements were carried out in the context of four explicit individual scenarios namely: line of sight (LOS) and non-LOS (NLOS) walking, rotational and random movements. The measurements were repeated within three different indoor environments and considered three different hypothetical body worn node locations. With the aid of these results, the parameters for the $\kappa-\mu$ / gamma composite fading model were estimated and analyzed extensively. Interestingly, for the majority of the indoor environments and movement scenarios, the parameter estimates suggested that dominant signal components existed even when the direct signal path was obscured by the test subject's body. Additionally, it is shown that the $\kappa-\mu$ / gamma composite fading model provides an adequate fit to the fading effects involved in off-body communications channels. Using the Kullback-Leibler divergence, we have also compared our results with another recently proposed shadowed fading model, namely the $\kappa-\mu$ / lognormal LOS shadowed fading model. It was found that the $\kappa-\mu$ / gamma composite fading model provided a better fit for the majority of the scenarios considered in this study.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Corrosion fatigue is a fracture process as a consequence of synergistic interactions between the material structure, corrosive environment and cyclic loads/strains. It is difficult to be detected and can cause unexpected failure of engineering components in use. This study reveals a comparison of corrosion fatigue behaviour of laser-welded and bare NiTi wires using bending rotation fatigue (BRF) test coupled with a specifically-designed corrosion cell. The testing medium was Hanks’ solution (simulated body fluid) at 37.5 oC. Electrochemical impedance spectroscopic (EIS) measurement was carried out to monitor the change of corrosion resistance of sample during the BRF test at different periods of time. Experiments indicate that the laser-welded NiTi wire would be more susceptible to the corrosion fatigue attack than the bare NiTi wire. This study can serve as a benchmark for the product designers and engineers to understand the corrosion fatigue behaviour of the NiTi laser weld joint and determine the fatigue life safety factor for NiTi medical devices/implants involving laser welding in the fabrication process.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Thesis (Master's)--University of Washington, 2015-12

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Master Thesis in Mechanical Engineering field of Maintenance and Production

Relevância:

30.00% 30.00%

Publicador:

Resumo:

OBJECTIVE: Both subclinical hypothyroidism and the metabolic syndrome have been associated with increased risk of coronary heart disease events. It is unknown whether the prevalence and incidence of metabolic syndrome is higher as TSH levels increase, or in individuals with subclinical hypothyroidism. We sought to determine the association between thyroid function and the prevalence and incidence of the metabolic syndrome in a cohort of older adults. DESIGN: Data were analysed from the Health, Ageing and Body Composition Study, a prospective cohort of 3075 community-dwelling US adults. PARTICIPANTS: Two thousand one hundred and nineteen participants with measured TSH and data on metabolic syndrome components were included in the analysis. MEASUREMENTS: TSH was measured by immunoassay. Metabolic syndrome was defined per revised ATP III criteria. RESULTS: At baseline, 684 participants met criteria for metabolic syndrome. At 6-year follow-up, incident metabolic syndrome developed in 239 individuals. In fully adjusted models, each unit increase in TSH was associated with a 3% increase in the odds of prevalent metabolic syndrome (OR, 1.03; 95% CI, 1.01-1.06; P = 0.02), and the association was stronger for TSH within the normal range (OR, 1.16; 95% CI, 1.03-1.30; P = 0.02). Subclinical hypothyroidism with a TSH > 10 mIU/l was significantly associated with increased odds of prevalent metabolic syndrome (OR, 2.3; 95% CI, 1.0-5.0; P = 0.04); the odds of incident MetS was similar (OR 2.2), but the confidence interval was wide (0.6-7.5). CONCLUSIONS: Higher TSH levels and subclinical hypothyroidism with a TSH > 10 mIU/l are associated with increased odds of prevalent but not incident metabolic syndrome.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In response to a looming leadership shortage, leadership development for teachers has become an increasingly important area of interest around the world. A review of the literature identified the key components of educational leadership development programs as effective curriculum, leadership practice, relationship building, and reflection. A gap in the research was found regarding the use of voluntary committee work as a vehicle for leadership practice. The purpose of this study was to explore teachers' perceptions of their experiences within board-level committees to determine the key factors that contributed, positively or negatively, to their leadership,pevelopment. A qualitative research design was employed using semistructured interviews with 8 participants. The key findings included a list of factors perceived by teachers as either supporting or hindering their leadership development. The supporting factors were: (a) leadership practice, (b) mentors and role models, (c) relationships and networks, and (d) positive outcomes for students. The hindering factors were: (a) lack of follow through and support, (b) committee members with a careerist approach to the experience, (c) personal and political agendas, and (d) overcommitment leading to burnout. Recommendations for practice focused on strategies to enhanc~_ the committee experience as a tool for leadership development. Recommendations for theory and research suggested more research be done on each of the 8 key factors, perceptions associated with teachers choosing to follow a leadership path, and how school boards can structure the committee process as an effective leadership development tool. This study provides a starting point for educators to begin to intentionally design, develop, and deliver voluntary committee experiences as a tool for leadership development.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Variation in hiring procedures occurs within fire service human resource departments. In this study, City 1 and City 2 applicants were required to pass their biophysical assessments prior to being hired as firefighters at the beginning and end of the screening process, respectively. City 1 applicants demonstrated significantly lower resting heart rate (RHR), resting diastolic blood pressure (RDBP), body fat% (BF) and higher z-scores for BF, trunk flexibility (TF) and overall clinical assessment (p<0.05). Regression analysis found that age and conducting the biophysical assessment at the end of the screening process explained poorer biophysical assessment results in BF% (R2=21%), BF z-score (R2=22%), TF z-score (R2=10%) and overall clinical assessment z-score (R2=7%). Each of RHR (OR=1.06, CI=1.01-1.10), RDBP (OR=1.05, CI=1.00-1.11) and BF% (OR=1.20, CI=1.07-1.37) increased the odds of being a City 2 firefighter (p<0.05). Biophysical screening at the end of the hiring process may result in the hiring of a less healthy firefighter.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Delta isobar components in the nuclear many-body wave function are investigated for the deuteron, light nuclei (16O), and infinite nuclear matter within the framework of the coupled-cluster theory. The predictions derived for various realistic models of the baryon-baryon interaction are compared to each other. These include local (V28) and nonlocal meson exchange potentials (Bonn2000) but also a model recently derived by the Salamanca group accounting for quark degrees of freedom. The characteristic differences which are obtained for the NDelta and Delta Delta correlation functions are related to the approximation made in deriving the matrix elements for the baryon-baryon interaction.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The challenge of reducing carbon emission and achieving emission target until 2050, has become a key development strategy of energy distribution for each country. The automotive industries, as the important portion of implementing energy requirements, are making some related researches to meet energy requirements and customer requirements. For modern energy requirements, it should be clean, green and renewable. For customer requirements, it should be economic, reliable and long life time. Regarding increasing requirements on the market and enlarged customer quantity, EVs and PHEV are more and more important for automotive manufactures. Normally for EVs and PHEV there are two important key parts, which are battery package and power electronics composing of critical components. A rechargeable battery is a quite important element for achieving cost competitiveness, which is mainly used to story energy and provide continue energy to drive an electric motor. In order to recharge battery and drive the electric motor, power electronics group is an essential bridge to convert different energy types for both of them. In modern power electronics there are many different topologies such as non-isolated and isolated power converters which can be used to implement for charging battery. One of most used converter topology is multiphase interleaved power converter, pri- marily due to its prominent advantages, which is frequently employed to obtain optimal dynamic response, high effciency and compact converter size. Concerning its usage, many detailed investigations regarding topology, control strategy and devices have been done. In this thesis, the core research is to investigate some branched contents in term of issues analysis and optimization approaches of building magnetic component. This work starts with an introduction of reasons of developing EVs and PEHV and an overview of different possible topologies regarding specific application requirements. Because of less components, high reliability, high effciency and also no special safety requirement, non-isolated multiphase interleaved converter is selected as the basic research topology of founded W-charge project for investigating its advantages and potential branches on using optimized magnetic components. Following, all those proposed aspects and approaches are investigated and analyzed in details in order to verify constrains and advantages through using integrated coupled inductors. Furthermore, digital controller concept and a novel tapped-inductor topology is proposed for multiphase power converter and electric vehicle application.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In this paper we present a component based person detection system that is capable of detecting frontal, rear and near side views of people, and partially occluded persons in cluttered scenes. The framework that is described here for people is easily applied to other objects as well. The motivation for developing a component based approach is two fold: first, to enhance the performance of person detection systems on frontal and rear views of people and second, to develop a framework that directly addresses the problem of detecting people who are partially occluded or whose body parts blend in with the background. The data classification is handled by several support vector machine classifiers arranged in two layers. This architecture is known as Adaptive Combination of Classifiers (ACC). The system performs very well and is capable of detecting people even when all components of a person are not found. The performance of the system is significantly better than a full body person detector designed along similar lines. This suggests that the improved performance is due to the components based approach and the ACC data classification structure.