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991.
Haodong Shi Jieqiong Qin Pengfei Lu Cong Dong Jian He Xiujian Chou Pratteek Das Jiemin Wang Liangzhu Zhang Zhong-Shuai Wu 《Advanced functional materials》2021,31(28):2102314
High-efficiency lithium–sulfur (Li–S) batteries depend on an advanced electrode structure that can attain high sulfur utilization at lean-electrolyte conditions and minimum amount of lithium. Herein, a twinborn holey Nb4N5–Nb2O5 heterostructure is designed as a dual-functional host for both redox–kinetics–accelerated sulfur cathode and dendrite-inhibited lithium anode simultaneously for long-cycling and lean-electrolyte Li–S full batteries. Benefiting from the accelerative polysulfides anchoring–diffusion–converting efficiency of Nb4N5–Nb2O5, polysulfide-shutting is significantly alleviated. Meanwhile, the lithiophilic nature of holey Nb4N5–Nb2O5 is applied as an ion-redistributor for homogeneous Li-ion deposition. Taking advantage of these merits, the Li–S full batteries present excellent electrochemical properties, including a minimum capacity decay rate of 0.025% per cycle, and a high areal capacity of 5.0 mAh cm−2 at sulfur loading of 6.9 mg cm−2, corresponding to negative to positive capacity ratio of 2.4:1 and electrolyte to sulfur ratio of 5.1 µL mg−1. Therefore, this work paves a new avenue for boosting high-performances Li–S batteries toward practical applications. 相似文献
992.
Channel Assignment Strategies for Multiradio Wireless Mesh Networks: Issues and Solutions 总被引:3,自引:0,他引:3
Next-generation wireless mobile communications will be driven by converged networks that integrate disparate technologies and services. The wireless mesh network is envisaged to be one of the key components in the converged networks of the future, providing flexible high- bandwidth wireless backhaul over large geographical areas. While single radio mesh nodes operating on a single channel suffer from capacity constraints, equipping mesh routers with multiple radios using multiple nonoverlap- ping channels can significantly alleviate the capacity problem and increase the aggregate bandwidth available to the network. However, the assignment of channels to the radio interfaces poses significant challenges. The goal of channel assignment algorithms in multiradio mesh networks is to minimize interference while improving the aggregate network capacity and maintaining the connectivity of the network. In this article we examine the unique constraints of channel assignment in wireless mesh networks and identify the key factors governing assignment schemes, with particular reference to interference, traffic patterns, and multipath connectivity. After presenting a taxonomy of existing channel assignment algorithms for WMNs, we describe a new channel assignment scheme called MesTiC, which incorporates the mesh traffic pattern together with connectivity issues in order to minimize interference in multi- radio mesh networks. 相似文献
993.
Prasad Rohit Das Satyajit Martin Kevin J. M. Coussy Philippe 《Journal of Signal Processing Systems》2021,93(10):1159-1171
Journal of Signal Processing Systems - Coarse Grained Reconfigurable Arrays (CGRAs) are emerging as energy efficient accelerators providing a high grade of flexibility in both academia and... 相似文献
994.
Atul Shukla Sarah K. M. McGregor Robert Wawrzinek Siddhartha Saggar Evan G. Moore Shih-Chun Lo Ebinazar B. Namdas 《Advanced functional materials》2021,31(15):2009817
Over the years, achieving efficient electroluminescence (EL) while simultaneously having low light amplification thresholds under optical excitation has been the key to progression toward the long-thought objective of electrically pumped organic lasers. While significant progress in this regard has been made for organic semiconductors emitting in the blue–green region of the visible spectrum, organic laser dyes with low-energy emission (>600 nm) still suffer from high amplified spontaneous emission (ASE) thresholds and low external quantum efficiencies (EQEs) in devices. Herein, low ASE thresholds and efficient EL are reported from a solution-processable organic laser dye dithiophenyl diketopyrrolopyrrole (DT-DPP). The ASE threshold of 4 µJ cm−2 at the wavelength of 620 nm is obtained while making constructive use of triplet excitons by doping DT-DPP in a green-emitting host matrix, which exhibits thermally activated delayed fluorescence (TADF). The organic light-emitting diode fabricated from this system gives a high EQE of 7.9% due to the efficient utilization of triplet excitons. Transient EL studies further show that a high reverse intersystem crossing rate is crucial in achieving lasing under electrical pumping from such TADF-assisted fluorescent systems. 相似文献
995.
Gullo L.J. Azarian M.H. Das D. Schenkelberg F. Tiku S. 《Components and Packaging Technologies, IEEE Transactions on》2006,29(2):425-428
A reliability capability assessment process can assist OEMs and system integrators in assessing prospective suppliers for their ability to design and manufacture reliable products before they are delivered for use, and on an ongoing basis, help a company in identifying shortcomings in its reliability program, which can be rectified by subsequent improvement actions. The assessment can also help to establish reliability management practices for use by designers, suppliers, customers, and independent authorities. The assessment method may be used to evaluate the reliability capability of all types of electronics-related industries that perform activities influencing the reliability of a product. It can produce increased customer satisfaction, provide competitive opportunities, and shorten the product development cycle. In summary, a reliability capability assessment can be used for: 1) specifying or planning reliability practices if product development is implemented internally; 2) evaluating reliability practices to determine the extent to which a supplier is capable of providing a product that meets the reliability requirements/needs; and 3) improving reliability practices if the current reliability practices have been evaluated and improvement is desired or required. 相似文献
996.
Sensory data gathered from sensor nodes in physical proximity tend to exhibit strong correlation. To minimize such redundancy and hence curtail the load in wireless sensor networks with a goal to conserve energy, effective in-network fusion schemes have been extensively proposed in the literature. To this end, routing schemes supporting data fusion are extremely important as they dictate where and when sensory data streams shall intersect with each other and thus fusion will be performed. In this article we briefly articulate this problem and classify recently proposed routing schemes supporting data fusion in wireless sensor networks into three categories: routing-driven, coding-driven, and fusion-driven. We also give an overview of various algorithms in each category by summarizing their design approaches, benefits, and drawbacks. 相似文献
997.
Singh S.N. Sharma S.K. Singh P.K. Das B.K. 《Electron Devices, IEEE Transactions on》1992,39(2):362-369
A realistic model of a front-illuminated n+-p-p+ silicon solar cell is developed by solving the current continuity equations for minority carriers in the quasi-neutral regions in steady state, assuming the light in the cell is trapped as a result of multiple reflections at the front and the back of the cell. This model is used to study the effects of the front emitter thickness and doping level and the light trapping on the J -V characteristic and thereby on the open-circuit voltage, short-circuit current density, curve factor, and the efficiency of the cell. A textured cell with an emitter thickness in the range of 0.3-1.0 μm with its doping ≈5×1018 cm-3 and the recombination velocities of minority carriers as large as 200 cm/s at the n+ front surface and 10 cm/s at the back of the p base can exhibit an efficiency in excess of 26% (under AM 1.5 sunlight of 100 mW/cm2 intensity) at 25°C if the light reflection losses at the front surface can be made small 相似文献
998.
Das K. K. Walker S. G. Bhushan M. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2007,95(3):670-687
An integrated computer-aided design (CAD) framework for evaluating MOSFET and layout parasitic extraction (LPE) models and circuit simulators used in the timing and power analysis of CMOS products is presented. This unified CAD methodology builds a step-wise understanding of the underlying parameter values in the models and their impact on circuit performance. A number of circuit experiments are included to extract the contributions of key MOSFET parameters and physical layout sensitive parasitic elements from circuit simulation results. This CAD setup thus allows easy and detailed comparison of different technologies, device models, and LPE tools to prevent possible bugs in the software as well as inaccuracies in device and parasitic models and timing tools. The software code to carry out the circuit simulations, analysis, and display of the results in an automated fashion has been specifically developed to support this framework. Some of the experiments designed for this work are also placed on the product chip for model-to-hardware correlation. The comparison of the hardware data to the model predictions points to the sources of any discrepancies and aids in tuning the product design to reflect changes in the technology as part of an overall design for manufacturing (DFM) platform 相似文献
999.
In this paper, we propose two information-theoretic techniques for efficiently trading off the location update and paging costs associated with mobility management in wireless cellular networks. Previous approaches always attempt to accurately convey a mobile's movement sequence and hence cannot reduce the signaling cost below the entropy bound. Our proposed techniques, however, exploit the rate distortion theory to arbitrarily reduce the update cost at the expense of an increase in the corresponding paging overhead. To this end, we describe two location tracking algorithms based on spatial quantization and temporal quantization, which first quantize the movement sequence into a smaller set of codewords and then report a compressed representation of the codeword sequence. Although the spatial quantization algorithm clusters individual cells into registration areas, the more powerful temporal quantization algorithm groups sets of consecutive movement patterns. The quantizers themselves are adaptive and periodically reconfigure to accommodate changes in the mobile's movement pattern. Simulation study with synthetic and real movement traces for both single-system and multisystem cellular networks demonstrate that the proposed algorithms can reduce the mobile's update frequency to 3-4 updates/day with reasonable paging cost, low computational complexity, storage overhead, and codebook updates. 相似文献
1000.
In this paper, the authors present second degree polynomial approximated phase-only synthesis of two different types of symmetric sector or flat-top beams of equally spaced linear antenna arrays of isotropic radiators with single pre-fixed cosine on a pedestal amplitude distributions using real-coded or real-valued genetic algorithm. This gives a regular shape to the phase distributions of the radiators. Regular shape phase distributions result in simpler feed network design compared to irregular shape phase distributions. A good agreement between desired and synthesized pattern using genetic algorithm (GA) is reported. 相似文献