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排序方式: 共有1002条查询结果,搜索用时 15 毫秒
51.
The introduction of the Internet of Things (IoT) paradigm serves as pervasive resource access and sharing platform for different real-time applications. Decentralized resource availability, access, and allocation provide a better quality of user experience regardless of the application type and scenario. However, privacy remains an open issue in this ubiquitous sharing platform due to massive and replicated data availability. In this paper, privacy-preserving decision-making for the data-sharing scheme is introduced. This scheme is responsible for improving the security in data sharing without the impact of replicated resources on communicating users. In this scheme, classification learning is used for identifying replicas and accessing granted resources independently. Based on the trust score of the available resources, this classification is recurrently performed to improve the reliability of information sharing. The user-level decisions for information sharing and access are made using the classification of the resources at the time of availability. This proposed scheme is verified using the metrics access delay, success ratio, computation complexity, and sharing loss. 相似文献
52.
53.
Facile Synthesis of Ultrasmall CoS2 Nanoparticles within Thin N‐Doped Porous Carbon Shell for High Performance Lithium‐Ion Batteries 下载免费PDF全文
Qingfei Wang Ruqiang Zou Wei Xia Jin Ma Bin Qiu Asif Mahmood Ruo Zhao Yangyuchen Yang Dingguo Xia Qiang Xu 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(21):2511-2517
Cobalt sulfide (CoS2) is considered one of the most promising alternative anode materials for high‐performance lithium‐ion batteries (LIBs) by virtue of its remarkable electrical conductivity, high theoretical capacity, and low cost. However, it suffers from a poor cycling stability and low rate capability because of its volume expansion and dissolution of the polysulfide intermediates in the organic electrolytes during the battery charge/discharge process. In this study, a novel porous carbon/CoS2 composite is prepared by using nano metal–organic framework (MOF) templates for high‐preformance LIBs. The as‐made ultrasmall CoS2 (15 nm) nanoparticles in N‐rich carbon exhibit promising lithium storage properties with negligible loss of capacity at high charge/discharge rate. At a current density of 100 mA g?1, a capacity of 560 mA h g?1 is maintained after 50 cycles. Even at a current density as high as 2500 mA g?1, a reversible capacity of 410 mA h g?1 is obtained. The excellent and highly stable battery performance should be attributed to the synergism of the ultrasmall CoS2 particles and the thin N‐rich porous carbon shells derieved from nanosized MOF precusors. 相似文献
54.
Sajid Bashir Muhammad Naeem Adnan Ahmed Khan Syed Ismail Shah 《International Journal of Communication Systems》2010,23(1):109-124
The paper discusses a sequence detector based on univariate marginal distribution algorithm (UMDA) that jointly estimates the symbols transmitted in a multiple input multiple output (MIMO) communication system. While an optimal maximum likelihood detection using an exhaustive search method is prohibitively complex, it has been shown that sphere decoder (SD) achieves the optimal bit error rate (BER) performance with polynomial time complexity for smaller array sizes. However, the worst‐case complexity of SD is exponential in the problem dimensions, this brings in question its practical implementation for larger number of spatial layers and for higher‐order signal constellation. The proposed detector shows promising results for this overly difficult and complicated operating environment, confirmed through simulation results. A performance comparison of the UMDA detector with SD is presented for higher‐order complex MIMO architectures with limited average transmit power. The proposed detector achieves substantial performance gain for higher‐order systems attaining a near optimal BER performance with reduced computational complexity as compared with SD. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
55.
Asif Khan Alam Zaib Irfan Ullah Shahid Khattak 《International Journal of Communication Systems》2020,33(6)
This paper presents link to system (L2S) interfacing technique for multiple input and multiple output (MIMO) iterative receivers. In L2S interfacing, usually the post detection signal to noise ratio (SNR)‐based frame error rate lookup tables (LUT) are used to predict the link level performance of receivers. While L2S interfacing for linear MIMO receivers can be conveniently implemented, it is more challenging for MIMO iterative receivers due to unavailability of the closed form SNR expressions. In this paper, we propose three methods for post detection SNR estimation for MIMO iterative receivers. The first is based on the QR decomposition of the channel matrix, the second relies on the residual noise calculation based on the soft symbols, and the third exploits the closed form SNR expressions for linear receivers. A link to system interface model for iterative receivers is developed for evaluating the reference curves for different modulation and coding schemes, and results are validated by comparing the simulated and predicted frame error rates. It is shown that linear and residual noise‐based SNR approximations result in a very good prediction performance whereas the performance of QR decomposition‐based method degrades for higher order modulations and coding schemes. This paper presents link to system interfacing technique for MIMO iterative receivers. A link to system interface model for iterative receivers is developed for evaluating the reference curves for different modulation and coding schemes, and results are validated by comparing the simulated and predicted frame error rates. Three post detection SNR evaluation schemes have been proposed for link to system interfacing all of which give good prediction performance especially at lower order modulation. 相似文献
56.
Muhammad Asif Xin Gao Hongjie Lv Xinguo Xi Pengyu Dong 《International Journal of Hydrogen Energy》2018,43(5):2726-2741
Electricity and water from renewable hydropower plant are used as input for electrolysis unit to generate hydrogen, while CO2 is captured from 600 MW supercritical coal power plant using post-combustion chemical solvent based technology. The captured CO2 and H2 generated through electrolysis are used to synthesize methanol through catalytic thermo-chemical reaction. The methanol synthesis plant is designed, modeled and simulated using commercial software Aspen Plus®. The reactor is analyzed for two widely adopted kinetic models known as Graaf model and Vanden-Bossche (VB) model to predict the methanol yield and CO2 conversion. The results show that the methanol reactor based on Graaf kinetic model produced 0.66 tonne of methanol per tonne of CO2 utilized which is higher than that of the VB kinetic model where 0.6 tonne of methanol is produced per tonne of CO2 utilized. The economic analysis reveals that 1.2 billion USD annually is required at the present cost of both H2 production and CO2 abatement to utilize continuous emission of 3.2 million tonne of CO2 annually from 600 MW supercritical coal power unit to synthesize methanol. However, sensitivity analysis indicates that methanol production becomes feasible by adopting anyone of the route such as by increasing methanol production rate, by reducing levelised cost of hydrogen production, by reducing CO2 mitigation cost or by increasing the current market selling price of methanol and oxygen. 相似文献
57.
Ayaz Arif Khan Muhammad Umer Fayaz Muhammad Nasir Khan Mazhar Iqbal Asif Majeed Rehana Bilkees Surayya Mukhtar Muhammad Javed 《Journal of Materials Science: Materials in Electronics》2018,29(16):13577-13587
Here in, we report the charge transport mechanism in semiconducting La0.5Ca0.5Mn0.5Fe0.5O3 (LCMFO) polycrystalline material synthesized via sol–gel auto combustion route. X-ray diffraction (XRD) analysis confirmed the orthorhombic phase of the prepared material. Temperature dependent resistivity and impedance spectroscopy measurements have been carried out to probe the dielectric and electrical conduction mechanism which revealed a change of Mott variable range to the small polaronic hopping conduction mechanism around 303 K. The complex impedance and modulus spectra undoubtedly showed the contribution of both grain and grain boundary effect on the conduction properties of LCMFO. An equivalent circuit [(RgbQgb) (RgQg)] model has been used to address the electrical parameters associated with the different phases (grains and grain boundaries) having different relaxation times. The values of resistances of two phases obtained after fitting the equivalent circuit in the nyquist plot have been analyzed which confirmed the change of conduction mechanism around 303 K. The resultant change in conduction mechanism is also supported by the conductivity plots. 相似文献
58.
Tarik Uzunovic Asif Sabanovic 《International Journal of Control, Automation and Systems》2018,16(5):2043-2054
When a complex task has to be performed by multiple systems, it imposes functional dependencies between the states and/or outputs of the systems. These functional dependencies create a system of’ virtually’ interconnected subsystems, even though they may be physically separated. The component subsystems within the overall system we call ‘functionally related systems’. This paper deals with motion control design for functionally related systems. The design is based on identifying functions. The control design is then performed by projecting the system dynamics into the function space. The main goal is to obtain unit control distribution matrix in the function space and enforce a desired dynamics for each of the identified functions. 相似文献
59.
Ahmad Awais Ahmad Mudassar Habib Muhammad Asif Sarwar Shahzad Chaudhry Junaid Latif Muhammad Ahsan Dar Saadat Hanif Shahid Muhammad 《The Journal of supercomputing》2019,75(4):2269-2288
The Journal of Supercomputing - The main challenge in database-as-a-service is the security and privacy of data because service providers are not usually considered as trustworthy. So, the data... 相似文献
60.
Muhammad Khalid Bashir Steven Schilizzi 《Journal of the science of food and agriculture》2013,93(6):1251-1258
This paper reviews the determinants of rural household food security in Africa and Asia where more than 88% of the world's undernourished people live. A conceptual model is proposed on the basis of the three widely known components of food security: food availability, accessibility and utilisation. This model is used to select a total of 40 peer‐reviewed studies carried out over the last decade (20 each from Africa and Asia). A meta‐analysis technique is then used to identify which determinants of food security have been highlighted and how well the causality is demonstrated. Food availability is the most studied component in both regions, followed by food accessibility, while food utilisation is the most neglected component in these studies. © 2013 Society of Chemical Industry 相似文献