民办高校90后大学生体育课态度调查分析

运用调查法、文献法与分析法,从认知、情感、意志三个维度,对广州市6所民办高校1000名90后大学生体育课整体态度进行调查分析．调查数据表明：1）学生对体育课定位偏颇较大;2）学生体育课需求达成度不高;3）学生的体育活动参与形式偏向于课外锻炼;4）学生对体育课器材自备有较大负面情绪;5）学生对体育教师综合评价较好．     

挠性航天器大角度姿态机动路径规划

针对挠性航天器大角度姿态快速机动快速稳定的控制要求,通过分析挠性航天器姿态动力学特性,提出了一种基于抛物线型角加速度曲线的三段式机动路径规划算法.该算法考虑了机动过程中对最大角加速度与最大角速度限制,充分发挥执行机构的功能来提高系统的快速性,并使角加速度平滑变化以减小帆板的振动.该路径规划方法简单,适于在轨实现.仿真结...     

设计初期建筑HVAC负荷敏感性分析:城市环境下的购物中心

城市环境及设计参数的多样性使购物中心的冷热负荷具有多重不确定性。通过3种典型购物中心在2种城市环境下的敏感性分析,旨在确定寒冷气候下的关键设计参数。采用拉丁超立方抽样获得200种设计组合方式,通过不确定性及敏感性分析,得到购物中心冷热负荷的波动情况及16个设计参数的敏感性排序。不确定性分析表明,设计参数引起全年HVAC （供暖通风与空气调节）负荷高达62.3%的变化,热负荷的变化幅度是冷负荷的5倍;敏感性分析表明,入口风速、天窗屋顶面积比和屋面传热系数是影响寒冷地区购物中心的建筑全年HVAC负荷的3个重要设计参数;城市环境影响表明,建筑密集地区对冷负荷的需求低于空旷地区,同时,外窗太阳得热系数的敏感性在空旷地区明显高于建筑密集地区。     

基于改进LuGre摩擦模型的机器人关节模糊自适应反步控制

为实现机器人关节在非线性摩擦和外界未知干扰力矩等因素影响下的精确和稳定控制,通过改进LuGre摩擦模型来描述系统的非线性摩擦特性,采用自适应算法进行摩擦补偿来逼近摩擦力的变化,并采用模糊神经网络逼近外界未知干扰力矩对系统的影响.引入正切障碍李雅普诺夫（Lyapunov）函数对输出信号进行约束,使误差被限制在给定范围之内.利用双曲正弦函数跟踪微分器解决了虚拟输入微分引起的“微分爆炸”和一阶滤波器精度差问题,将自适应控制方法与反步控制理论相结合,提出了一种带摩擦补偿的模糊自适应反步控制方法.利用Lyapunov判据证明了闭环系统的所有误差最终一致有界,并通过仿真得出本文所提出的控制方法相比于传统PID与神经网络动态面控制（Radial Basis Function Dynamic Surface Control,RBFDSC）,位置跟踪误差分别提高了近7.5%和3%;当LuGre模型参数变化时,自适应算法也可以精确对摩擦力进行跟踪补偿,从而验证了本文所提出的控制策略的有效性和鲁棒性.     

基于风险域的城市道路交叉口交通冲突分析方法

提出了基于风险域的交通冲突分析二阶段法。采用inD数据集,通过车辆到达风险域的时间（t_TTR）进行交通冲突识别,再根据风险域内的持续时间来判定交通冲突的风险程度。结果表明：与基于碰撞时间（t_TTC）的方法相比,该方法不仅能够更有效地识别追尾冲突和相交冲突,还能够表征不同时刻交通冲突的风险程度。     

Retailers’ Order Strategies in Transshipments in Disruption Risks of Supply Chains

This article investigates the order problem in a two-stage supply chain consisting of retailers, primary suppliers and backup suppliers. From retailers’ perspectives, the optimal offering strategies in unidirectional transshipments are analyzed on the basis of disruption risks in supply chains. With a focus on retailers’ profits, it develops the decision model of retailers’ orders in the dual sourcing mode and in the mode of capacity options, to maximize the retailers’ expected profits. The simulation shows that retailers’ optimal order decisions are not correlated with the joint disruption probability in the two order modes without service constraints; retailers’ optimal decisions are influenced by the joint disruption probability in the two order modes with service constraints, and the impact of the joint disruption probability of the primary suppliers’ optimal order from retailers differs in the two modes. Retailers’ order decisions in respect of backup suppliers are more sensitive to the changing volumes of transshipments. The contribution of this article is the impact of main parameters on retailers’ decisions, providing some guidance for enterprises to make order decisions.     

Stable isotopes of modern herbivore tooth enamel in the Tibetan Plateau: Implications for paleoelevation reconstructions

Fossil tooth enamel from herbivores is considered one of the best proxies for paleoclimate and paleoelevation reconstructions, due to its low susceptibility to diagenetic alteration. A synthesis of oxygen and carbon isotope analyses of modern tooth enamel from herbivores such as Tibetan yaks, asses and antelopes is assessed. The average δ 13C(PDB) value of herbivore tooth enamel in the Lhasa and south Qiangtang terrains is-11.3‰± 1.1‰, whereas in the north Qiangtang and Hoh Xil terrains value is-10.2‰± 1.4‰...     

Modeling the intracellular dynamics for Vif-APO mediated HIV-1 virus infection

The viral infectivity factor (Vif) was found to be essential for controlling HIV-1 virus infectivity. It targets cellular antiviral proteins in APOBEC family (APO) to trigger its fast degradation and inhibits APO packaging into nascent virion. In the present study, we propose a mathematical model to quantitatively study the intracellular dynamics of these typical virus-host interactions. Four sets of published experimental data were compared with simulation results to justify the model. Systematic parameter sensitivity and perturbation analysis showed that parameters related to APO are crucial to the infectivity of newly synthesized HIV-1 virus. Interestingly, we discovered that the synthesis rate of the viral structure protein Gag and the required number per nascent virion are optimized to achieve high virion production with minimal level of packaged APO, and large portion of model parameters are beneficial to virus only within a relatively small range. Furthermore, minor variations in several parameters related to viral protein Tat, the activator of viral RNA synthesis, were found to induce switch-like behaviors on both incorporated Vif and APO. These findings may provide new insights for understanding the high mutation rate of HIV-1 virus and its latency, as well as help identify key targets for therapeutic design.     

基于信道缩短的UWB信道最小二乘估计

在使用最小二乘算法进行超宽带(UWB)信道估计时,当信道冲激响应的长度大于发送脉冲的帧长度,则在接收端会产生各个脉冲冲激响应之间的相互干扰,影响信道估计的效果.提出使用信道缩短技术,对实际信道的长度进行缩短,估计出缩短信道后再恢复成实际的超宽带信道.仿真实验表明,在信道长度大于脉冲帧长度时,仍然能很好地估计出信道,有效地解决干扰问题.