异步垂直空时结构中的功率扩展技术

在平坦衰落信道中,针对异步垂直贝尔实验室空时结构(V-BLAST)信号模型下,现有线性最佳检测算法误码率性能随信噪比提高改善缓慢的问题,提出一种基于功率扩展的迭代检测方法:发射端用功率扩展将发射信号扩展到整个空时信号块上,接收端进行基于功率扩展的迭代检测。同时,分析了所提方法在每次迭代检测后的误码率性能。分析和仿真验证了误码率性能的改进。在4发4收场景下,误码率为10^-5时,相比于线性最优最小均方误差(MMSE)方法,获得了约6dB信噪比增益。     

钣金自动展开及数控切割

阐述怎样利用AutoCAD二次开发技术开发软件钣金自动展开系统及怎样应用自动编程软件自动编程,实现数控下料。     

Sustained Effects of CGRP Blockade on Cortical Spreading Depolarization-Induced Alterations in Facial Heat Pain Threshold,Light Aversiveness,and Locomotive Activity in the Light Environment

A migraine is clinically characterized by repeated headache attacks that entail considerable disability. Many patients with migraines experience postdrome, the symptoms of which include tiredness and photophobia. Calcitonin gene-related peptide (GGRP) is critically implicated in migraine pathogenesis. Cortical spreading depolarization (CSD), the biological correlate of migraine aura, sensitizes the trigeminovascular system. In our previous study, CSD caused hypomotility in the light zone and tendency for photophobia at 72 h, at which time trigeminal sensitization had disappeared. We proposed that this CSD-induced disease state would be useful for exploring therapeutic strategies for migraine postdrome. In the present study, we observed that the CGRP receptor antagonist, olcegepant, prevented the hypomotility in the light zone and ameliorated light tolerability at 72 h after CSD induction. Moreover, olcegepant treatment significantly elevated the threshold for facial heat pain at 72 h after CSD. Our results raise the possibility that CGRP blockade may be efficacious in improving hypoactivity in the light environment by enhancing light tolerability during migraine postdrome. Moreover, our data suggest that the CGRP pathway may lower the facial heat pain threshold even in the absence of overt trigeminal sensitization, which provides an important clue to the potential mechanism whereby CGRP blockade confers migraine prophylaxis.     

铝/钢微束等离子熔钎焊接头组织及力学性能

采用微束等离子焊接方法进行6010铝合金/镀锌钢对接熔钎焊工艺试验,在合适的工艺参数下获得成形良好的铝/钢熔钎焊对接接头,采用金相显微镜、扫描电子显微镜、能谱仪、拉伸试验机等多种测试手段对所得接头形貌、微观组织及力学性能进行分析. 结果表明,所得接头焊缝正、背面铺展良好,无气孔、裂纹、夹渣等明显缺陷,为典型的铝/钢熔钎焊对接接头;接头界面处形成锯齿状的Fe₂Al₅金属间化合物,且金属间化合物层厚度和焊缝铺展宽度共同决定了接头强度,当焊接电流为38.5 A时,熔钎焊接头抗拉强度为193 MPa,为铝母材的79.8%,接头断裂形式为韧脆混合断裂.     

自由项对交通流双曲型方程组数值解影响研究

该文以交通流模型中不同平衡函数表达式为例,对一阶非线性双曲型方程组的自由项形式与数值解的色散性、耗散性之间关系,进行了数值模拟研究。结果发现：自由项对方程组数值解的色散性和耗散性影响都是比较有规律的,这种规律性在不同初始密度条件下是不一样的;自由项导致方程组数值解色散或耗散强弱,与方程组的离散方式也有关,尤其在中等密度条件下。就Payne-Whitham模型方程,建议了能够对不同初始密度下扰动的传播和发展进行合理数值模拟的自由项和离散方式。     

免调度非正交多址接入上行链路的非2幂次长度二元扩频序列

为了解决5G大规模机器类通信场景下大规模接入和如何提高频谱效率的问题,该文针对免调度非正交多址接入(NOMA)系统上行链路,通过采用插入函数在2元Golay序列上插入元素的方法,提出具有低峰均功率比(PAPR)且长度为非2幂次的2元扩频序列集。仿真结果表明,得到的序列集具有低相干性,这为基于压缩感知的活跃用户检测提供了可靠的性能。同传统的Zadoff-Chu序列相比,新型2元序列集具有更小的字符集,便于实现。此外,所构造的序列PAPR最大为4,低于高斯随机序列和Zadoff-Chu序列,因此可以有效解决时域信号峰均功率比过高的问题。     

The costs and profitability of using granulated wood ash as a forest fertilizer in drained peatland forests

Increasing and more intensive energy wood harvesting from forests necessitate efforts to ensure that adequate amounts of nutrients are recycled back onto the site. Recycling nutrients back to the forest in the form of wood ash is a natural means to correct the nutrient imbalance and acidity of forest soils that can occur from intensive management, as well as to solve the problem of disposing of wood combustion wastes. Methods of refining and spreading have been developed to improve the logistics and cost competitiveness of recycling wood ash back into the forest as fertilizer. In this study, the costs of spreading granulated wood ash in the forest were calculated under Finnish conditions. The profitability of recycling wood ash to drained peatland forests as a fertilizer was also analyzed, from the forest owner’s point of view. For this analysis, wood ash was compared with chemical fertilizer in terms of effect, cost and profitability. Wood ash fertilization using the ground-based forwarder system was two to three times cheaper than using the aerial helicopter-loader system. From the forest owner’s point of view, the fertilization of peatland forest with wood ash proved to be a very profitable silvicultural investment (IRR 3-12 percent). To improve the economics of wood ash recycling to forests, ground-based spreading of granulated ash should be emphasized. Furthermore, in order to create large enough operational units for the cost-efficient spreading of ash, there needs to be comprehensive planning of spreading sites.     

关于“冷轧扭”及“冷轧带肋”钢筋的推广与应用

阐述了“冷轧扭”及“冷轧带肋”钢筋的推广应用情况,对“冷轧带肋”与“冷轧扭”钢筋的物理力学性能、经济效益、强度等级等进行了对比分析,得出的结论为“冷轧带肋”及“冷轧扭”钢筋是一种强度高、延性好、锚固性能优良的新型高效钢材。此项技术必将给建筑企业带来更大的经济效益。     

爆炸荷载作用下材料裂纹扩展速度的实验研究

本文从理论上分析了裂纹的扩展速度，并在此基础上对爆炸荷载作用下大理岩，水泥砂浆和有机玻璃中裂纹的扩展速度进行了实验测定和讨论分析，实测和分析结果表明，爆炸荷载作用下材料的裂纹扩展速度随时间的变化规律可以多项式曲线进行良好拟合。     

龙滩碾压混凝土层间砂浆摊铺机的研制

提出了应用仿形原理实现的碾压混凝土坝层间砂浆摊铺机械，在施工现场进行了摊铺机的模型实验，论述了砂浆摊铺机设计中的关键技术。理论分析和现场模型试验表明，采用仿形原理的摊铺机是可行的，它对摊铺质量和速度都能提供保障。