以用户为中心的可见光通信协作传输中训练资源分配算法

以用户为中心的可见光通信协作传输是近年来出现的新架构,这导致虚拟小区之间出现重叠。为避免导频污染问题,每个虚拟小区中的光接入点(AP)或者虚拟小区中选择相同AP的用户发送的训练序列应该是正交的。针对可见光通信中以用户为中心的协作网络,研究训练资源的正交分配问题,提出了一种新的导频分配算法,联合导频分配和用户选择问题,以期最大限度地增加虚拟小区内可被接入的用户数。分析和仿真结果表明,该导频分配方案可以有效改善导频污染问题,提高训练资源利用率,并且相比已有的导频分配方案,性能有所改进。     

Effects of Rare Earths on Toughness of 31Mn2SiRE Wear-Resistance Cast Steel

The toughness of 31Mn2SiRE wear-resistance cast steel were increased by means of RE compound modification and high temperature austenitizing. The results show that the microstructures can be refined, needle and network ferrite are eliminated, the dislocation density and the quantity of dislocated martensite are increased remarkably, and the shape and distribution of inclusions are improved by the addition of RE. Therefore, the mechanical properties of the modified steel can be greatly increased, especially the toughness (αK) by 44%, yield strength (σs) by 10%, and elongation (δ5) by 42%.     

钙矾石膨胀机理的SEM研究

本文利用扫描电镜观察了在具有不同矿物组成的系统中生成的钙矾石的形成与膨胀机理。发现能够产生膨胀的钙矾石是由局部化学反应所生成；它们在未水化的铝酸盐矿物表面原地结晶，呈放射状生长。通过溶解，沉淀生成的钙矾石不能凝结，没有膨胀性。     

P+RE变质对过共晶Al-Si合金组织性能的影响

以过共晶Al-Si合金为研究对象，分析了P＋RE变质对合金组织及力学性能的影响，并分析探讨了其强化机制。结果表明，变质后合金组织中粗大块状、条状的初晶Si尺寸明显细化，粗大针状的共晶Si变为纤维状或短杆状，合金的力学性能提高。当P含量为0．08％和RE含量为0．6％时，其室温和高温力学性能最好，室温抗拉强度从未变质的236．2MPa提高到287．6MPa，高温抗拉强度从142．5MPa提高到210MPa，分别提高了22％和47％；伸长率分别提高了57％和42％。初晶Si的变质以AIP异质形核作用机理为主，共晶Si以RE吸附产生孪晶为变质机制。     

基于Matlab的双馈风力发电机组动态特性研究

随着能源的大量消耗,人们越来越重视可持续发展能源,风力发电由于其可再生性得到了很好的发展.现阶段的风力发电是比较成熟的一种发电形式.在分析了变速恒频双馈发电机组的工作原理的基础上,建立了风电机组的数学模型,利用Matlab软件对基于双馈感应发电机的变速风电机组进行了仿真,得到了风电机组正常运行和电网故障两种条件下的动态输出特性.     

Polyethylenimine-modified sugarcane bagasse cellulose as an effective adsorbent for removing Cu(II) from aqueous solution

Polyethylenimine-modified sugarcane bagasse cellulose (SBCMP), as a new adsorbent, was synthesized by the reaction of polyethylenimine (PEI) with sugarcane bagasse cellulose and glutaraldehyde. The adsorption of Cu(II) by SBCMP was pH-dependent, and the higher removal efficiency of Cu(II) appeared in the range of pH 3.0–6.0. The adsorption isothermal data fitted well with the Langmuir model, and the maximum adsorption capacity of SBCMP was up to 107.5 mg/g. The adsorption kinetics was best described by the pseudo-second-order kinetic. The adsorption of Cu(II) by SBCMP was unfavorable at high temperatures, and thermodynamic analyses implied that the adsorption of Cu(II) by SBCMP was an exothermic reaction. Fourier transform infrared spectroscopy (FT-IR) combined with X-ray photoelectron spectroscopy (XPS) revealed that Cu(II) adsorption on SBCMP mainly controlled by the nitrogen atoms of  NH group in PEI. The results of regeneration cycles showed that SBCMP was suitable for reuse in the adsorption of Cu(II) from aqueous solution. These experimental results suggested that SBCMP is expected to be a new biomass adsorbent with high efficiency in removing Cu(II) from wastewater.     

模板法制备结构可控纳米材料的研究进展

综述了模板法制备结构可控纳米材料的研究进展,讨论了模板法可控制备纳米材料的原理及高度有序自组装的纳米多孔Al2O3模板的形成机理。重点介绍了纳米材料的可控制备方法,主要包括纳米多孔Al2O3模板法、聚合物模板法和生物模板法。其中纳米多孔Al2O3模板法又分为电化学纳米多孔Al2O3模板合成法和电化学诱导的溶胶-凝胶方法等。根据材料的物化性能,选用适合的模板,采用合理的工艺路线,可以制备出结构可控的纳米材料。     

高职计算机应用基础课程实训教学改革的探索与实践

根据高等职业教育的培养目的和教学特点以及非计算机专业《计算机应用基础》课程实践教学标准的要求,文章从加强《计算机应用基础》课程的实训教学出发,根据学生的不同专业和实际情况,探讨了加强实训教学的方法和科学合理检查和评价学生的方法,总结了《计算机应用基础》课程在高职教育教学改革中一些行之有效的经验,全面提高学生的计算机实际应用能力。     

ARP病毒的分析与防护

现代化的办公系统往往都离不开对电脑的使用,企业和部门电脑运行的稳定尤为重要,由于人们为对电脑的使用不当,或是信息管理部门的管理疏忽,使我们的网络经常受到电脑病毒的干扰,特别是常见的ARP病毒,比如聚生网管、P2P终结者、网络执法官、网络剪刀手、局域网终结者等。ARP病毒通常表现为网络传播快,感染终端定位困难等特点,一旦感染就导致大面积的计算机终端无法进行网络访问     

19.28% Efficiency and Stable Polymer Solar Cells Enabled by Introducing an NIR-Absorbing Guest Acceptor

Here, a near-infrared (NIR)-absorbing small-molecule acceptor (SMA) Y-SeNF with strong intermolecular interaction and crystallinity is developed by combining selenophene-fused core with naphthalene-containing end-group, and then as a custom-tailor guest acceptor is incorporated into the binary PM6:L8-BO host system. Y-SeNF shows a 65 nm red-shifted absorption compared to L8-BO. Thanks to the strong crystallinity and intermolecular interaction of Y-SeNF, the morphology of PM6:L8-BO:Y-SeNF can be precisely regulated by introducing Y-SeNF, achieving improved charge-transporting and suppressed non-radiative energy loss. Consequently, ternary polymer solar cells (PSCs) offer an impressive device efficiency of 19.28% with both high photovoltage (0.873 V) and photocurrent (27.88 mA cm⁻²), which is one of the highest efficiencies in reported single-junction PSCs. Notably, ternary PSC has excellent stability under maximum-power-point tracking for even over 200 h, which is better than its parental binary devices. The study provides a novel strategy to construct NIR-absorbing SMA for efficient and stable PSCs toward practical applications.