12bit 800MSPS电流舵结构的高速DAC设计

本文设计了一个分辨率为12位，采样频率为800MHz的高速电流舵结构DAC。该设计基于TSMC0．18umCMOS工艺，采用了二进制码控制和温度计码译码控制相结合的方式，从而在降低DNL误差和减小毛刺的同时，又能实现较小的芯片面积和功耗。为达到高的精度和高的转换速度，该设计在系统结构、电路结构以及芯片版图等方面都做了优化。     

Spider orb webs rely on radial threads to absorb prey kinetic energy

The kinetic energy of flying insect prey is a formidable challenge for orb-weaving spiders. These spiders construct two-dimensional, round webs from a combination of stiff, strong radial silk and highly elastic, glue-coated capture spirals. Orb webs must first stop the flight of insect prey and then retain those insects long enough to be subdued by the spiders. Consequently, spider silks rank among the toughest known biomaterials. The large number of silk threads composing a web suggests that aerodynamic dissipation may also play an important role in stopping prey. Here, we quantify energy dissipation in orb webs spun by diverse species of spiders using data derived from high-speed videos of web deformation under prey impact. By integrating video data with material testing of silks, we compare the relative contributions of radial silk, the capture spiral and aerodynamic dissipation. Radial silk dominated energy absorption in all webs, with the potential to account for approximately 100 per cent of the work of stopping prey in larger webs. The most generous estimates for the roles of capture spirals and aerodynamic dissipation show that they rarely contribute more than 30 per cent and 10 per cent of the total work of stopping prey, respectively, and then only for smaller orb webs. The reliance of spider orb webs upon internal energy absorption by radial threads for prey capture suggests that the material properties of the capture spirals are largely unconstrained by the selective pressures of stopping prey and can instead evolve freely in response to alternative functional constraints such as adhering to prey.     

太原高铁客运站站房建筑

与传统铁路客运相比,高速铁路客运具有方便、迅速、舒适、运输能力大的优势。以太原高铁客运站站房设计为例,通过合理总体布局和建筑设计,从建筑的文化特性,以及技术先进性包括新型屋面体系、幕墙系统和建筑节能等方面,充分发挥上述高速客运的优势,吸引旅客,提供安全高效舒适的客运服务。     

高速电梯补偿绳张紧装置设计中的两个问题

针对高速电梯补偿绳张紧装置，提出了补偿绳张紧重量的计算和选取方法。详细分析了电梯紧急制动状态下补偿绳张紧装置及防跳装置的工作状态，并建立了相应的动力学方程，通过相关数学推导和分析得出了防跳装置动作反力的计算方法。     

中国轨道铁路建设及其对铝材需求(2)

主要介绍中国可制造铝合金轨道车辆企业生产的动车组列车的性能特点,以及中国轨道车辆、城市轨道建设等对铝材的需求.在铝合金机车车辆制造中,单车的平均用铝量约10.3 t.其中挤压铝材约占78％,其他铝材占22％左右.     

我国高铁建设融资模式再探索

作为公共基础设施建设的重要组成部分,高铁建设具有自然垄断性、地方公共产品性、成本积聚性以及收益长期性等经济属性。高铁建设一般采取政府投资为主、BOT项目融资为辅的融资模式,而政府投资和BOT项目融资模式都存在一定的限制,为满足高铁建设的巨大资金需求,需要探索和尝试更可行、合理的融资模式,制定支持性政策和配套制度。     

Passenger comfort on high-speed trains: effect of tunnel noise on the subjective assessment of pressure variations

When passing through a tunnel, aerodynamic effects on high-speed trains may impair passenger comfort. These variations in atmospheric pressure are accompanied by transient increases in sound pressure level. To date, it is unclear whether the latter influences the perceived discomfort associated with the variations in atmospheric pressure. In a pressure chamber of the DLR-Institute of Aerospace Medicine, 71 participants (M = 28.3 years ± 8.1 SD) rated randomised pressure changes during two conditions according to a crossover design. The pressure changes were presented together with tunnel noise such that the sound pressure level was transiently elevated by either +6 dB (low noise condition) or +12 dB (high noise condition) above background noise level (65 dB(A)). Data were combined with those of a recent study, in which identical pressure changes were presented without tunnel noise (Schwanitz et al., 2013, ‘Pressure Variations on a Train – Where is the Threshold to Railway Passenger Discomfort?’ Applied Ergonomics 44 (2): 200-209). Exposure-response relationships for the combined data set comprising all three noise conditions show that pressure discomfort increases with the magnitude and speed of the pressure changes but decreases with increasing tunnel noise.

Practitioner Summary: In a pressure chamber, we systematically examined how pressure discomfort, as it may be experienced by railway passengers, is affected by the presence of tunnel noise during pressure changes. It is shown that across three conditions (no noise, low noise (+6 dB), high noise (+12 dB)) pressure discomfort decreases with increasing tunnel noise.     

公路滑坡防治与实例分析

通过对滑坡类型及成因的认识,采用数值模拟及相关规范规程计算,针对性的制定相应的解决措施,并通过实例来阐述治理方案的重要性,以期有效、经济、合理的解决公路上的地质灾害。     

基于集约策略的城市高铁综合交通枢纽地区规划模式探析——以三明南站枢纽地区规划为例

本文以对高铁枢纽地区的特征分析为基础，对于土地资源紧缺的城市，提出集约模式开发策略来开展交通枢纽地区的规划建设，以解决在多层次空间利用、功能定位、交通组织等方面面临的问题。具体对策包括TOD模式、功能复合、交通一体化、门户景观营造等。以福建三明南站地区为例，从功能、空间、交通和景观等方面探讨了集约开发策略在高铁交通枢纽地区的实际应用。     

一种新的低渗透气藏产能方程

综合分析滑脱效应、启动压力梯度效应和高速非达西效应,依据渗流力学原理建立稳定渗流条件下综合考虑三种效应影响的低渗透气藏产能方程.应用该方程对不同滑脱系数和不同启动压力梯度下的流入动态曲线进行比较.在相同井底流压下,随着滑脱效应影响因子的增大,气井产能逐渐增大；随着启动压力梯度的增大,气井产能逐渐减小.