摘要：Microchannel has demonstrated advantages in the thermal management of integrated chip. In this study, the topology optimization method is applied for designing a topological microchannel to optimize the performances of both heat dissipation and pressure drop. To validate the performance of the topological structure, the flow and heat transfer characteristics of topological microchannel under non-uniform heating flux are numerically studied. The topological structure is designed to cool a heating area of 10 mm×10 mm with 4 hotspots. Heat flux is 40 W/cm^2 in the hotspot area, while it is only 15 W/cm^2 in the rest heating area. The results of heat dissipation performance and pressure drop are compared with those of conventional straight microchannel. Numerical result shows that, compared to the straight microchannel, the hotspot temperature and pressure drop of topological microchannel can be reduced by 4 and 0.6 k Pa, respectively, under the flow rate of 2.2×10^-4 kg/s. The coefficient of performance(COP) of topological microchannel can be 16.1% better than that of straight microchannel, which can be attributed to the effects of optimized bifurcation and confluence structural of topological microchannel.

摘要：为优化边坡生态防护中的滴灌应用,通过室内模型试验深入探讨了滴灌均匀度和流量偏差率受滴灌管长度、初始水头和滴头间距的影响机制。采用室内滴灌管出流试验,设置4种滴灌管长度、3种初始水头和3种滴头间距的试验因素,依据试验数据计算了各因素下滴灌均匀度和流量偏差率。分析了滴定管长度、初始水头和滴头间距对滴灌参数的影响规律,选取了合适的滴灌设计参数值。对试验提供的滴灌设计参数进行应用,选取现场试验段进行边坡滴灌养护,验证滴灌设计的效果。研究结果表明:滴灌管长度、初始水头和滴头间距对滴灌均匀度和流量偏差率具有显著影响。滴灌管长度在30~40 m时,灌水均匀度均大于0.8,符合规范要求;滴灌管长度为30 m,相比于长度为40 m时,初始水头的增加对灌水均匀度增加效应减弱了。滴头间距增加可以提高灌水均匀度,但对流量偏差率的影响不显著。初始水头为2~3 m时,滴灌管流量偏差率变化值很接近,分别为0.159、0.167、0.157,在3 m水头流量偏差率基本降低至0.45以下,基本满足灌溉要求。选取了离隰高速公路LJ4标段工程边坡作为试验区,验证了滴灌系统设计的可靠性,并根据实际情况进行了微调,确保了滴灌效果的优化。试验区种植的紫穗槐生长情况良好,成活率高,验证了滴灌技术在黄土边坡中生态护坡运用的有效性和可行性。

摘要：为控制反应堆功率偏离临界程度,以某压水堆核电站为例,开展负荷跟踪反应堆功率控制方法的设计研究。根据反应性随时间的变化函数,建立核电站负荷跟踪反应性模型;在考虑阶跃变化的条件下,根据反应堆功率和反应性的动态关系,计算反应堆功率负荷动态变化;基于汽轮机负荷信号变化,进行反应堆的功率控制。实例应用实验结果表明设计的方法在反应堆功率控制的应用中展现出了良好的控制效果,不仅能够有效地控制反应堆的偏离临界程度,而且能够使其稳定地达到理想状态。

摘要：设计了一款抗辐射16位25 MS/s流水线型模数转换器(ADC)。根据电容失配等因素确定了第一级4位的流水线结构,并设计了改进的自举开关来提高采样线性度。为了降低系统功耗,设计了一种开关电容动态偏置电路,通过减小放大器的平均电流来降低ADC的系统功耗。为了满足抗辐射的要求,针对电离总剂量效应和单粒子闩锁效应的机理,对电路进行抗辐射加固设计。该款抗辐射ADC在0.18μm CMOS工艺上进行制造,转换器的芯片面积为2.5 mm^(2),经过辐射试验后,在采样率25 MHz、1.8 V电源电压和30.1 MHz正弦输入的条件下,ADC的信噪比(SNR)达到了76.7 dBFS,无杂散动态范围(SFDR)为95.1 dBFS,功耗为38.76 mW,抗辐射能力达到电离总剂量100 Krad(Si)和单粒子闩锁阈值75 MeV·cm^(2)/mg,可满足空间环境的使用要求。

摘要：【目标】针对隧道发生火灾时大客车人员下车时间开展研究,以解决公路隧道火灾下的人员安全疏散的问题。【方法】结合大客车人员疏散特性,明确了人员必需安全疏散时间由报警时间、响应时间、下车时间及疏散时间组成。采用现场试验研究紧急与非紧急情况下人员的疏散特性;运用数值模拟分析大客车不同类型人员,尤其是老年人在大客车中的不同乘车位置对下车时间的影响。【结果】人员在非紧急和紧急情况下疏散速度差距较大,人员平均下车所需时间分别为72.86 s和41.75 s;在体型和疏散速度的综合影响下,成年女性和成年男性下车时间相当,约为49 s,老年人下车时间为104.8 s;下车时间随着老年人数量的增加而增加,当老年人处在最后一排和中间排时,下车时间最长。【结论】非紧急情况下的人员下车时间明显长于紧急情况;老年人和年轻人在下车时间上存在显著差异;老年人在大客车中的特定乘车位置对下车时间影响较大,但老年人人数超过一定数量后下车时间受老年人位置的影响较小,建议将大客车人员下车时间设定为75 s。【应用】研究成果可为公路隧道火灾下的人员必需安全疏散时间计算提供重要参考。

摘要：Thermal protection systems are very essential for high temperature thermal conductivity measurement system to reduce the heat loss to environment at the range of 600-1800 K. A compound multi-layer insulations structure which composed of inner carbon fibrous materials and outer alternately arranged alumina fibrous materials and high reflectivity foils is proposed for use in high temperature cylinder thermal protection systems. A coupled conductive and radiation governing equations is presented for heat transfer analysis of the structure. The finite volume method and the discrete ordinate method are used to solve the goveming equations. The optimization structure of the compound multi-layer insulations is investigated by considering the pressure of the gas, the density of the carbon fibrous materials, the density of the alumina fibrous materials, the number of reflective foil layers and the emissivity of reflective foils. The results show that the compound structure has the best thermal insulation performance when the pressure of the gas is below 0.01 kPa, the density of carbon fibrous materials is 180 kg m^-3, the density of alumina fibrous materials is 256 kg m^-3 and the number of reflective foil layers is 39. In addition, the thermal insulation performance is much better when the emissivity of reflective foils is lower.

摘要：为了满足无人机助推架的研制需求,设计了一种以高压二氧化碳气体驱动的适用于固定翼无人机的可拆卸式发射助推架。结合气体炮内弹道方程,建立了气体发射的数学模型,通过理论计算和利用动力学仿真软件ADAMS对设计的三维模型进行仿真,得到了不同质量无人机发射时的初速、过载、位移等变化规律。结果显示,通过仿真得到的无人机离开发射架时的初速、位移、过载变化曲线与理论计算结果高度一致,验证了计算与仿真的正确性。研究结果表明,该固定翼无人机助推发射架在不超过最大过载的情况下,能够成功发射14 kg及以下无人机并达到起飞初速,仿真结果与理论计算误差不超过3%。研究结果可进一步为气体发射提供理论指导。

摘要：Recently, the structural fuse has become an important issue in the field of earthquake engineering. Due to the trilinearity of the pushover curve of buildings with metallic structural fuses, the mechanism of the structural fuse is investigated through the ductility equation of a single-degree-of-freedom system, and the corresponding damage-reduction spectrum is proposed to design and retrofit buildings. Furthermore, the controlling parameters, the stiffness ratio between the main frame and structural fuse and the ductility factor of the main frame, are parametrically studied, and it is shown that the structural fuse concept can be achieved by specific combinations of the controlling parameters based on the proposed damage-reduction spectrum. Finally, a design example and a retrofit example, variations of real engineering projects after the 2008 Wenchuan earthquake, are provided to demonstrate the effectiveness of the proposed design procedures using buckling restrained braces as the structural fuses.

摘要：随着城市的不断发展,城市交通拥堵问题日益突出,智能车站作为综合交通体系的关键节点,能够实现各种交通方式的高效衔接和协同运作,提升城市交通的整体运行效率,在城市整体规划中占据重要地位。以城市绿舟为设计主题,梳理城市公交车站发展现状,从智能公交车站外形和功能两个维度进行优化设计,为乘客提供更加智能化、人性化的乘车体验。

摘要：Isoamylene from the Fischer-Tropsch syncrude can be transformed to valuable fuel oxygenate additives through an equilibrium limited etherification reaction with methanol. A reactive distillation process is established to increase isoamylene conversion. Facing the challenge of improving product purity at the same time, an equilibrium stage model based design methodology is proposed and illustrated step-by-step for converting the Fischer-Tropsch C_5 olefins to tert-amyl methyl ether(TAME) process by using Aspen Plus. Under the guide of the proposed methodology, the design leads to a TAME product purity of higher than 95% and an isoamylene conversion of higher than 90%. The etherification kinetics over Amberlyst 35 is also studied within a temperature range of 60 ℃ to 75 ℃ to shed more light on the feasibility of process development. The methodology provides an effective reactive distillation column design to achieve the target reactant conversion and product purity simultaneously.