Cross‐Layer Resource Allocation Scheme for WLANs with Multipacket Reception

Tailored for wireless local area networks, the present paper proposes a cross‐layer resource allocation scheme for multiple‐input multiple‐output orthogonal frequency‐division multiplexing systems. Our cross‐layer resource allocation scheme consists of three stages. Firstly, the condition of sharing the subchannel by more than one user is studied. Secondly, the subchannel allocation policy which depends on the data packets’ lengths and the admissible combination of users per subchannel is proposed. Finally, the bits and corresponding power are allocated to users based on a greedy algorithm and the data packets’ lengths. The analysis and simulation results demonstrate that our proposed scheme not only achieves significant improvement in system throughput and average packet delay compared with conventional schemes but also has low computational complexity.     

磁控溅射Ge/Si多层膜X射线低角衍射界面结构分析

本文对磁控溅射不同结构的Ｇｅ／Ｓｉ多层膜样品进行了Ｘ射线衍射的测试和分析,并进一步采用有过渡层的光学多层膜衍射模型对衍射谱进行了拟合;获得了扩散层厚度和分层厚度等多层膜的结构参数,定性讨论了多层膜中互扩散与分层厚度铁关系。计算结果与实验结果符合较好。     

深入教育改革探索培养创新人才的新思路

为培养适应２１世纪飞速发展的科技竞争需要的优秀人才,我们对现有培养模式所进行的教育改革中,作了一些尝试。吸取ＭＩＴ等国外著名大学的成功办学经验,总结我院在原有教改试点班工作中所取得的成绩,组建了ＭＩＴ电子信息试点班,并以此为突破口．寻求培养宽厚型创新人才的新思路,形成以信息为主线涉及多个学科基础理论的课程体系,带动面上教学。并论述了设立ＭＩＴ电子信息试点班的必要性和可能性,介绍了该试点班的培养目标和培养特色。     

键控特技在电视播出系统中的应用

介绍了键控特技的基本原理及分类,论述了键控特技应用于电视播出系统的必要性,并指出如何选择和使用适合于电视播出系统的键控混合器.     

新型横向脉冲快放电S_2激光管的设计

针对放电型 S2 激光管的设计中始终未能很好解决电极可拆卸性及可靠性的难题 ,首次提出了一个以不锈钢材料作激光管管壳 ,借助于燕尾槽实现电极可拆卸的设计方案 ,从而为横向脉冲快放电型 S2 激光器实现激光振荡创造了条件。     

智能复合材料光纤传感层的研究

光纤自诊断系统是智能复合材料结构的重要组成部分。但是 ,将光纤传感器阵列埋入复合材料是实现智能复合材料的一个难题。解决这一问题的方法是将光纤传感器集成在一起形成一个模块化的便于埋入复合材料中的光纤传感层。本文探讨两种使用聚酰亚胺制作传感层的方法。一种是把光纤传感器阵列埋入聚酰亚胺薄膜中 ;另一种是用作为光学材料的含氟聚酰亚胺制作矩形 (道沟 )光波导和光传感器。后一种方法制作的传感器模块集成度高、可靠性好 ,是值得注意的发展方向。     

Nonuniform sampling theorems for random signals in the linear canonical transform domain

Nonuniform sampling can be encountered in various practical processes because of random events or poor timebase. The analysis and applications of the nonuniform sampling for deterministic signals related to the linear canonical transform (LCT) have been well considered and researched, but up to now no papers have been published regarding the various nonuniform sampling theorems for random signals related to the LCT. The aim of this article is to explore the nonuniform sampling and reconstruction of random signals associated with the LCT. First, some special nonuniform sampling models are briefly introduced. Second, based on these models, some reconstruction theorems for random signals from various nonuniform samples associated with the LCT have been derived. Finally, the simulation results are made to prove the accuracy of the sampling theorems. In addition, the latent real practices of the nonuniform sampling for random signals have been also discussed.     

Coexistence of multiple bifurcation modes in memristive diode-bridge-based canonical Chua’s circuit

Based on a memristive diode bridge cascaded with series resistor and inductor filter, a modified memristive canonical Chua’s circuit is presented in this paper. With the modelling of the memristive circuit, a normalised system model is built. Stability analyses of the equilibrium points are performed and bifurcation behaviours are investigated by numerical simulations and hardware experiments. Most extraordinary in the memristive circuit is that within a parameter region, coexisting phenomenon of multiple bifurcation modes is emerged under six sets of different initial values, resulting in the coexistence of four sets of topologically different and disconnected attractors. These coexisting attractors are easily captured by repeatedly switching on and off the circuit power supplies, which well verify the numerical simulations.     

Direct 3D Printing of Ultralight Graphene Oxide Aerogel Microlattices

Graphene aerogel microlattices (GAMs) hold great prospects for many multifunctional applications due to their low density, high porosity, designed lattice structures, good elasticity, and tunable electrical conductivity. Previous 3D printing approaches to fabricate GAMs require either high content of additives or complex processes, limiting their wide applications. Here, a facile ion‐induced gelation method is demonstrated to directly print GAMs from graphene oxide (GO) based ink. With trace addition of Ca²⁺ ions as gelators, aqueous GO sol converts to printable gel ink. Self‐standing 3D structures with programmable microlattices are directly printed just in air at room temperature. The rich hierarchical pores and high electrical conductivity of GAMs bring admirable capacitive performance for supercapacitors. The gravimetric capacitance (C_s) of GAMs is 213 F g^?1 at 0.5 A g^?1 and 183 F g^?1 at 100 A g^?1, and retains over 90% after 50 000 cycles. The facile, direct 3D printing of neat graphene oxide can promote wide applications of GAMs from energy storage to tissue engineering scaffolds.     

Mobility Enhancement Technology for Scaling of CMOS Devices: Overview and Status

The aggressive downscaling of complementary metal–oxide–semiconductor (CMOS) technology to the sub-21-nm technology node is facing great challenges. Innovative technologies such as metal gate/high-k dielectric integration, source/drain engineering, mobility enhancement technology, new device architectures, and enhanced quasiballistic transport channels serve as possible solutions for nanoscaled CMOS. Among them, mobility enhancement technology is one of the most promising solutions for improving device performance. Technologies such as global and process-induced strain technology, hybrid-orientation channels, and new high-mobility channels are thoroughly discussed from the perspective of technological innovation and achievement. Uniaxial strain is superior to biaxial strain in extending metal–oxide–semiconductor field-effect transistor (MOSFET) scaling for various reasons. Typical uniaxial technologies, such as embedded or raised SiGe or SiC source/drains, Ge pre-amorphization source/drain extension technology, the stress memorization technique (SMT), and tensile or comprehensive capping layers, stress liners, and contact etch-stop layers (CESLs) are discussed in detail. The initial integration of these technologies and the associated reliability issues are also addressed. The hybrid-orientation channel is challenging due to the complicated process flow and the generation of defects. Applying new high-mobility channels is an attractive method for increasing carrier mobility; however, it is also challenging due to the introduction of new material systems. New processes with new substrates either based on hybrid orientation or composed of group III–V semiconductors must be simplified, and costs should be reduced. Different mobility enhancement technologies will have to be combined to boost device performance, but they must be compatible with each other. The high mobility offered by mobility enhancement technologies makes these technologies promising and an active area of device research down to the 21-nm technology node and beyond.