婴儿豆基粉中低植酸低异黄酮蛋白基料的制备工艺研究

为提升婴儿豆基配方粉的中蛋白基料的食用安全性,本研究从创新大豆蛋白制备工艺的角度出发,对大豆进行制浆浸提、酸沉、水洗等工艺获得蛋白产品,比较湿法、热烫法和半干法制浆工艺和关键环节对蛋白提取率、植酸和异黄酮去除率的影响。结果表明,当采用半干法制备蛋白浸提液后,再在pH5.15时酸沉并水洗离心获得大豆蛋白质,且体系中乳清保留量低于20%时,可以较好地控制植酸和异黄酮含量,其植酸和异黄酮含量分别为(12.08±0.46) mg/g和(1468±74) μg/g。利用此方法可较好的提高蛋白质基料的安全性,为进一步开发应用于婴儿豆基配方粉中的高安全性专用大豆蛋白粉基料奠定了基础。     

Modeling and optimization of an enhanced battery thermal management system in electric vehicles

Frontiers of Mechanical Engineering - This paper models and optimizes an air-based battery thermal management system (BTMS) in a battery module with 36 battery lithium-ion cells. A design of...     

超声速二元进气道吸除装置工程设计方法探索

针对一种起动马赫数Ma=2.0、设计马赫数Ma=3.0的超声速进气道,首先结合等激波强度和数值模拟的方法,分析了进气道各几何参数间的相互制约关系并设计了一种性能较优的传统构型。在此基础上,分析了不同边界层吸除装置对进气道性能的影响。结果表明,恰当的选择吸除装置和吸除流量,可明显增强进气道能够承受的最大反压并改善进气道在起动马赫数和设计马赫数下的总压恢复系数。探索了吸除装置合理的设计方法,可为工程设计提供一定的理论支撑。     

Numerical investigation on the effects of dike around liquid hydrogen source on vapor cloud dispersion

Safety is one of the most important concerns in handling liquid hydrogen. Mixture model and Realizable k-ε model are adopted to simulate the spills of liquid hydrogen in the present work. Effects of a dike around the liquid hydrogen source on vapor cloud dispersion are numerically investigated. The dike increases the hydrogen concentration near the source, and promotes the upward movement of flammable cloud thanks to the enhanced mixing with air, reducing the cloud detachment distance. The time needed for the hydrogen vapor cloud to be diluted out of hazards is largely influenced by dike size, and introducing the dike does not necessarily increase the overall hazard duration. Increasing the height to length ratio of the dike makes the near-source region exposed to high hydrogen concentration for longer hazard duration, while detachment distance reduces with the increment in dike height.     

Mixing and warming of cryogenic hydrogen releases

Laboratory measurements were made on the concentration and temperature fields of cryogenic hydrogen jets. Images of spontaneous Raman scattering from a pulsed planar laser sheet were used to measure the concentration and temperature fields from varied releases. Jets with up to 5 bar pressure, with near-liquid temperatures at the release point, were characterized in this work. This data is relevant for characterizing unintended leaks from piping connected to cryogenic hydrogen storage tanks, such as might be encountered at a hydrogen fuel cell vehicle fueling station. The average centerline mass fraction was observed to decay at a rate similar to room temperature hydrogen jets, while the half-width of the Gaussian profiles of mass fraction were observed to spread more slowly than for room temperature hydrogen. This suggests that the mixing and models for cryogenic hydrogen may be different than for room temperature hydrogen. Results from this work were also compared to a one-dimensional (streamwise) model. Good agreement was seen in terms of temperature and mass fraction. In subsequent work, a validated version of this model will be exercised to quantitatively assess the risk at hydrogen fueling stations with cryogenic hydrogen on-site.     

高压气动系统负载容腔压力伺服控制仿真研究

为满足某气体发生系统安装空间小、重量轻、动态响应快、控制精度高等要求,设计了高压气动压力伺服控制系统,并采用高压电-气伺服阀实现了负载压力的高响应高精度控制。建立了系统数学模型,包括高压气瓶热力学方程、高压电-气伺服阀传递函数与流量方程、负载容腔压力变化与排气流量方程等子模型,并设计了反馈线性化PID控制器。基于MATLAB/Simulink平台建立了高压气动系统仿真模型,仿真研究了高压气瓶容积与初始气源压力、负载容腔排气孔通径等参数对系统负载压力控制性能的影响规律。研究结果为该系统的优化设计与实验研究提供重要理论依据。     

Efficiency control of the cooling-down process of a cryogenic helium turbo-expander for a 2 t/d hydrogen liquefier

Efficient liquefaction of hydrogen is a crucial part for the large-scale storage and long-distance transportation of hydrogen. Helium Brayton cycle based on high-speed turbo-expanders has been widely employed in small and medium hydrogen liquefiers. In present study, a coupled model is proposed to predict the performance and cooling-down process of helium turbo-expanders with brake blower, and validation experiments were performed on a helium turbo-expander of a 2 t/d hydrogen liquefier. Experimental results indicated that the characteristic ratio of expander varied significantly during the cooling-down process which led to a large deviation from the optimal efficiency. The impact of brake pressure on the characteristic ratio and efficiency of the helium turbo-expander is studied, and a variable pressure control method is proposed for the efficient operation of turbo-expanders during the cooling-down process of a hydrogen liquefier. Compared with the constant brake pressure control method, the variable pressure control method can increase the expander efficiency by 5%–10% during the cooling-down process in the high temperature zone.     

Silica-based ceramics toward electromagnetic microwave absorption

Silica-based ceramics have been explored extensively as a class of versatile materials for various applications in architecture, catalysis, energy, machinery, and biomedical engineering. Nevertheless, comprehensive information on silica-based ceramic and electromagnetic microwave (EMW) absorption is scarce, although excellent progress has been made in this field. Here, recent progress in the investigation of silica-based ceramics toward EMW absorption is reviewed. We first introduced the basis of ceramics (characteristics, classification, synthetic methods, potential applications). Subsequently, the silica-based ceramics, including Si-based oxides and alloys, SiOC/SiC/Si₃N₄/SiCN-based composite, Ti₃SiC₂ and composite for EMW absorption were systematically summarized. Notably, the fabrication strategies, absorption properties, and mechanisms of silica-based ceramics are described in detail, with a focus on structure and component design. Lastly, the prospects and ongoing challenges of this field in the future are presented. This review is expected to learn from the past and achieve progress toward the future of silica-based ceramic for EMW absorption.     

基于BGSA算法的SVM分类模型设计研究

为了设计性能更优的支持向量机（SVM）分类模型,对影响其分类性能的参数和样本特征子集进行优化选择,对支持向量机理论和万有引力搜索算法（GSA）进行了研究,提出了一种基于二进制万有引力搜索算法（BGSA）的支持向量机分类模型构建方法,能够对影响支持向量机分类性能的相关参数及有效样本特征子集同时进行优化选择,获得最优组合解,并通过实验对其有效性进行了对比分析和验证。实验结果表明,所提出的BGSA-SVM分类模型能够有效提高支持向量机的分类性能,可进一步推广到工程实际中应用。     

大型火箭发动机试验导流槽热防护设计

火箭发动机热试车时喷射出的高温高速气流具有很大的冲击力和腐蚀力。导流槽的作用就是将燃气迅速地导向远离试车台的地方,防止火焰、烟尘及碎片反射回来冲击试验台,毁坏发动机和设备。随着我国大推力运载火箭研制立项,导流槽烧蚀的问题日益严峻。本文提出了一种新型导流槽热防护技术方案:通过数值分析和工程计算分析导流槽力、热环境;基于膜冷却原理,采用分区喷流水冷却的方法,根据热流密度不同在各区域采取不同的供水方式。此方案在保证导流槽冷却系统可靠性的同时,降低了试验台高度、节约了水资源。