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The Internet of Things (IoT) is a network of heterogeneous and smart devices that can make decisions without human intervention. It can connect millions of devices across the universe. Their ability to collect information, perform analysis, and even come to meaningful conclusions without human capital intervention matters. Such circumstances require stringent security measures and, in particular, the extent of authentication. Systems applied in the IoT paradigm point out high-interest levels since enormous damage will occur if a malicious, wrongly authenticated device finds its way into the IoT system. This research provides a clear and updated view of the trends in the IoT authentication area. Among the issues covered include a series of authentication protocols that have remained research gaps in various studies. This study applies a comparative evaluation of authentication protocols, including their strengths and weaknesses. Thus, it forms the foundation in the IoT authentication field of study. In that direction, a multi authentication architecture that involves secured means is proposed for protocol authentication. Informal analysis can affect the security of the protocols. Burrows-Abadi-Needham (BAN) logic provides proof of the attainment of mutual authentication. NS3 simulator tool is used to compare the performance of the proposed protocol to verify the formal security offered by the BAN logic.  相似文献   
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Nanonetworks consist of nano-sized communicating devices which are able to perform simple tasks at the nanoscale. The limited capabilities of individual nanomachines and the Terahertz (THz) band channel behavior lead to error-prone wireless links. In this paper, a cross-layer analysis of error-control strategies for nanonetworks in the THz band is presented. A mathematical framework is developed and used to analyze the tradeoffs between Bit Error Rate, Packet Error Rate, energy consumption and latency, for five different error-control strategies, namely, Automatic Repeat reQuest (ARQ), Forward Error Correction (FEC), two types of Error Prevention Codes (EPC) and a hybrid EPC. The cross-layer effects between the physical and the link layers as well as the impact of the nanomachine capabilities in both layers are taken into account. At the physical layer, nanomachines are considered to communicate by following a time-spread on-off keying modulation based on the transmission of femtosecond-long pulses. At the link layer, nanomachines are considered to access the channel in an uncoordinated fashion, by leveraging the possibility to interleave pulse-based transmissions from different nodes. Throughout the analysis, accurate path loss, noise and multi-user interference models, validated by means of electromagnetic simulation, are utilized. In addition, the energy consumption and latency introduced by a hardware implementation of each error control technique, as well as, the additional constraints imposed by the use of energy-harvesting mechanisms to power the nanomachines, are taken into account. The results show that, despite their simplicity, EPCs outperform traditional ARQ and FEC schemes, in terms of error correcting capabilities, which results in further energy savings and reduced latency.  相似文献   
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Wireless Personal Communications - This paper tackles the problem of Opportunistic Spectrum Access (OSA) in the Cognitive Radio (CR). The main challenge of a Secondary User (SU) in OSA is...  相似文献   
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Statistics show that the number of cars per capita in Syria is still low, but that the figure has more than doubled since 2004. Syria also suffers from inadequate public transport provision, poor infrastructure and the absence of suitable traffic management systems, with the average speed of road transport in Damascus at about 4–5 km/h. Only until very recently, a comprehensive network for the continuous monitoring of air pollutants has been lacking. This paper reviews, collates and synthesises the results of numerous studies of Syrian road transport, with an emphasis on air pollution from Syria's transport and energy production sectors. It is revealed that what studies that have been done show that the air quality in Syrian urban areas falls below established national air quality standards, especially during winter when the demand for heating is high. The paper proposes a number of suggestions to improve air quality in Syria by using greener and more public transport, promoting and incentivising rational and efficient energy consumption in all sectors, taking advantage of available renewable energy resources, establishing an active network for routine measurement of pollution, setting local emissions standards that are in line with international standards and which are supported by the imposition of penalties, fines or taxation on polluting agents.  相似文献   
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Considerable research has demonstrated how effective requirements engineering is critical for the success of software projects. Requirements engineering has been established and recognized as one of the most important aspects of software engineering as of late. It is noteworthy to mention that requirement consistency is a critical factor in project success, and conflicts in requirements lead to waste of cost, time, and effort. A considerable number of research studies have shown the risks and problems caused by working with requirements that are in conflict with other requirements. These risks include running overtime or over budget, which may lead to project failure. At the very least, it would result in the extra expended effort. Various studies have also stated that failure in managing requirement conflicts is one of the main reasons for unsuccessful software projects due to high cost and insufficient time. Many prior research studies have proposed manual techniques to detect conflicts, whereas other research recommends automated approaches based on human analysis. Moreover, there are different resolutions for conflicting requirements. Our previous work proposed a scheme for dealing with this problem using a novel intelligent method to detect conflicts and resolve them. A rule-based system was proposed to identify conflicts in requirements, and a genetic algorithm (GA) was used to resolve conflicts. The objective of this work is to assess and evaluate the implementation of the method of minimizing the number of conflicts in the requirements. The methodology implemented comprises two different stages. The first stage, detecting conflicts using a rule-based system, demonstrated a correct result with 100% accuracy. The evaluation of using the GA to resolve and reduce conflicts in the second stage also displayed a good result and achieved the desired goal as well as the main objective of the research.  相似文献   
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A constitutive model is developed in this work to describe the mechanical behavior of body centered cubic metals under a wide range of strain rates and temperatures. The model is based on macromechanical state variables such as stress, strain, and material constants that include threshold and transition temperature as well as micromechanical terms such as mobile dislocation density and burgers vector. The principle of the activation energy and its dependence on temperature, strain rate, and stress is the key point in this proposed model. The model is used to simulate the experimental behavior of pure iron at various temperatures and strain rates in order to obtain the different model parameters. The model shows good capability in capturing the coupling between strain rate and temperature, plastic strain and strain rate, and plastic strain and temperature. The model is used to characterize the hardness of iron at low and high strain rates for a representative strain of 8%.  相似文献   
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This paper reports the detailed statistical measurement of Young's modulus (E) and spring constant of micromachined three-dimensional polydimethylsiloxane microposts with various sizes using atomic force microscope. The paper also describes the design and fabrication of these microposts. The micropost array was fabricated with a height to diameter aspect ratio of up to 10. We have found that posts with different sizes have different E values, and posts that are cured at room temperature have smaller Young's modulus than the ones that are cured at 65?°C for the same duration.  相似文献   
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The Journal of Supercomputing - Lane detection is a technique that uses geometric features as an input to the autonomous vehicle to automatically distinguish lane markings. To process the intricate...  相似文献   
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