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81.
Recently, intelligent transportation systems (ITSs) have emerged. These systems can improve traditional transportation systems and provide traffic information to travelers. In the area of transportation, wireless sensor networks (WSNs) can replace the existing wired sensors and expensive traffic monitoring systems to mitigate the time and costs of installing such systems. However, accurate and on-time traffic information delivery is a major challenge, considering the energy constraints of sensor nodes. In this paper, we propose a two-tier architecture that includes a network of mobile objects (vehicles) in the upper layer and a hierarchical WSN in the bottom layer. Using this approach, a portion of loads on the low-power static sensor nodes can be transferred to mobile objects, such as powerful mobile devices. Moreover, to provide accurate and timely traffic information, a QoS-aware link cost function has been proposed and used for data transmission between the static sensor nodes. In addition, due to the mobility of the objects and the probability of losing packets in the mobile object tier, a reliable data forwarding mechanism has been proposed for this tier. In this mechanism, data packets are forwarded to the neighbors, which enhance the probability of the packets’ being received. The performance evaluation results indicate the effectiveness of the proposed architecture and data reporting mechanism for use in ITS applications.  相似文献   
82.
Two most important issues should be considered to achieve data delivery in DTN networking: routing protocols for the network and intelligent buffer management policy for everyone node in the network. The routing scheme decides which messages should be forwarded when nodes meet, and the buffer management policy determines which message is purged when the buffer overflows in a node. This study proposes a buffer management policy named as Dynamic Prediction based Multi Queue (DPMQ) for probabilistic routing protocols. It works by classification of local buffer into three queues of messages, which are DCTL, HPTL and LPTL. The simulation results have proven that the DPMQ performs well as compared to DLA, DOA, MOFO, LIFO, LEPR and LIFO in terms of reducing the message relay, message drop, hop counts average and overhead while rising in the delivery probability.  相似文献   
83.
We discuss robust M‐estimation of INARCH models for count time series. These models assume the observation at each point in time to follow a Poisson distribution conditionally on the past, with the conditional mean being a linear function of previous observations. This simple linear structure allows us to transfer M‐estimators for autoregressive models to this situation, with some simplifications being possible because the conditional variance given the past equals the conditional mean. We investigate the performance of the resulting generalized M‐estimators using simulations. The usefulness of the proposed methods is illustrated by real data examples.  相似文献   
84.
The primo vascular system (PVS) is observed in different parts of the body under different physiological and disease conditions. Previously, the PVS was not observed in the vagina. The vaginal samples of this study were collected from the female genitalia of healthy New Zealand white rabbits from the animal house, Faculty of Medicine, Assiut University. The vaginal samples were fixed in Bouin's solution. The sections were stained with hematoxylin and eosin and Crossmon's trichrome. Additionally, the sections were immunohistochemically stained with neuron-specific enolase (NSE) and vascular endothelial growth factor (VEGF). A primo node was observed on the lymph vessel of the vagina and has several characteristics that resemble those of the previously discovered primo nodes. The primo node in this study was surrounded by mesothelial cells that provide positive immunoreactivity to NSE and VEGF. Sinuses of different sizes, floating cells, telocyte-like cell, and primo microcells were observed as the main constituents of the primo node. Additionally, migratory cells were detected, which passed from the primo node to the enclosing lymph vessel.  相似文献   
85.
Multi-junction concentrator solar cells are a promising technology as they can fulfill the increasing energy demand with renewable sources. Focusing sunlight upon the aperture of multi-junction photovoltaic (PV) cells can generate much greater power densities than conventional PV cells. So, concentrated PV multi-junction solar cells offer a promising way towards achieving minimum cost per kilowatt-hour. However, these cells have many aspects that must be fixed to be feasible for large-scale energy generation. In this work, a model is developed to analyze the impact of various atmospheric factors on concentrator PV performance. A single-diode equivalent circuit model is developed to examine multi-junction cells performance in hot weather conditions, considering the impacts of both temperature and concentration ratio. The impacts of spectral variations of irradiance on annual performance of various high-concentrated photovoltaic (HCPV) panels are examined, adapting spectra simulations using the SMARTS model. Also, the diode shunt resistance neglected in the existing models is considered in the present model. The present results are efficiently validated against measurements from published data to within 2% accuracy. Present predictions show that the single-diode model considering the shunt resistance gives accurate and reliable results. Also, aerosol optical depth (AOD) and air mass are most important atmospheric parameters having a significant impact on HCPV cell performance. In addition, the electrical efficiency (η) is noticed to increase with concentration to a certain concentration degree after which it decreases. Finally, based on the model predictions, let us conclude that the present model could be adapted properly to examine HCPV cells' performance over a broad range of operating conditions.  相似文献   
86.
There is little information available about incidences and causes of foodborne illnesses that can help the government develop policies, which prevent them in the UAE. This study includes a group of multinational subjects (males and females), residing in Al Ain, UAE, and of an age ranging between 15 and 55 years. A questionnaire designed to assess “Knowledge” and “Practice” of public hygiene measures was piloted in a group of subjects from the public (n = 600). Data shows that 100% of highly educated subjects with postgraduate degrees (Master and PhD) have the proper information about food safety. However, only 70% of them always wash their hands before and after eating, while 80% always wash their hands after using toilets and frequently using warm water and soap. 29% of the total participants were inflicted with foodborne illness, and 85% read articles about food safety and personal hygiene. Most of the subjects in this study are Muslims, and they mainly depended on their daily attitude, which affects their personal hygiene because they must wash before praying. Data generally referred that awareness programs or training are needed, even for the highly educated members of the public. Further research is needed to explain the differences between reports of actual and usual behaviors.  相似文献   
87.
Wireless Networks - Maintaining durable connectivity during data forwarding in Vehicular Ad hoc Networks has witnessed significant attention in the past few decades with the aim of supporting most...  相似文献   
88.
Air-Breathing Proton Exchange Membrane Fuel Cells (AB-PEMFC) have the potential to supersede lithium-ion batteries in portable electronics. However, their water management issue has yet to be resolved to ensure optimum cell performance and safe system operation. In this paper, the formation of water droplets and their aggregation in the cathode flow channels of an operating AB-PEMFC is investigated by direct visualisation under various operating conditions. The developed optical set-up enables observation of droplet formation on the surface of the membrane from the top and side view of the channels simultaneously. The two orthogonal views reveal that during formation the receding and advancing droplet contact angles are almost identical with values that increase, in a similar trend to the droplet height, with increasing droplet diameter. Water films were able to develop and maintain direct contact with the side wall of the channels even under the effect of gravitational force. The aggregation of water droplets in the channels was strongly influenced by the change in the air and hydrogen stoichiometry conditions. However, these operating parameters appear to have no significant effect on the water extraction from the channels contrary to load and temperature, where temperature has proved to be the most effective water removal mechanism with minimum reduction in the current density of AB-PEMFC.  相似文献   
89.
The densities and kinematic viscosities of 10 binary subsystems of the regular quinary system, benzene (1) + toluene (2) + ethylbenzene (3) + heptane (4) + cyclooctane (5), were measured at 308.15 K and 313.15 K over the entire composition range. The viscosity-composition data reported herein were utilized to examine the predictive capability of some viscosity models, namely, the predictive version of the McAllister model, a group contribution method (GC-UNIMOD), a generalized corresponding states principle (GCSP), and the Allan and Teja correlation. The results of testing showed that the McAllister model outperformed all other models except for systems containing cyclooctane. The results also showed an overall average absolute deviation (%AAD) of 1.25% for systems that did not contain cyclooctane.  相似文献   
90.
Twelve subjects were treated with zidovudine, lamivudine, and ritonavir within 90 days of onset of symptoms of acute infection to determine whether human immunodeficiency virus type 1 (HIV-1) infection could be eradicated from an infected host. In adherent subjects, with or without modifications due to intolerance, viral replication was suppressed during the 24-month treatment period. Durable suppression reduced levels of HIV-1-specific antibodies and cytotoxic T lymphocyte responses in selected subjects. Proviral DNA in mononuclear cells uniformly persisted. The persistence of HIV-1 RNA expression in lymphoid tissues and peripheral blood mononuclear cells suggests that elimination of this residual pool of virus should be achieved before considering adjustments in antiretroviral therapeutic regimens. In addition, given the reduction in levels of virus-specific immune responses, it would seem prudent to consider enhancing these responses using vaccine strategies prior to the withdrawal of antiviral therapy.  相似文献   
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