某船用柴油机排气管路流-固耦合计算与保温效果研究

对某船用柴油机排气管路的流动与传热过程开展流-固耦合仿真分析。结果表明:受排气管路结构影响，管内流动方向和流速发生变化，局部区域产生明显的回流现象；排气管路外表面温度分布差异较大，平均温度高达534 ℃。为达到柴油机安全设计要求，在排气管路外壁敷设保温材料。分析结果表明:气凝胶纳米材料的保温效果优于硅酸铝纤维材料，在相同的运行条件和使用要求下，气凝胶纳米材料的敷设厚度更薄。     

A multi-material part design framework in additive manufacturing

Additive manufacturing (AM) technologies provide more freedom to functional part design in various industries. One of the unique capabilities of AM is that multi-material parts can be produced with material compositional and geometric complexity. Multi-material parts have the advantage of achieving multiple performance requirements. In the research, we propose a framework for designing multi-material parts using AM processes. The proposed framework is composed of four interacting modules, including design requirement identification, primary material selection, AM process selection, material composition, and part geometry determination. Rules and guidelines for AM are integrated into the proposed framework with AM processes’ capabilities and constraints compiled in databases. We also introduce databases to assist in decision-making and ensure manufacturability of the designed multi-material part in various product design phases. The proposed framework is applied to a case study involving a conceptual design of a multi-material battery pack cooling plate.     

一种波长调制干涉仪光强实时反馈控制系统

提出了一种实时反馈控制系统,保证波长调制干涉仪的激光光强在波长调谐过程中的稳定性,以减小波长调制干涉仪因激光光强的波动产生的相位误差。该控制系统由光电探测器、数据采集卡、光电调幅器和控制软件等组成。实验结果表明,该系统的响应速度超过了干涉仪获取干涉图的速度,不仅能够稳定输出理想的光强值,而且还提高了干涉仪的测量精度。     

Effect of nonsolvent additives on PES ultrafiltration membrane pore structure

Different nonsolvent additives, namely, diethylene glycol, n-butyl alcohol (NBA), and ethylene glycol monomethyl ether, were added into the casting solution (polyethersulfone/dimethylformamide/lithium chloride) to prepare ultrafiltration (UF) membrane via phase inversion. The effects of different additives and their concentration on the pore structure of the prepared UF membrane were studied. The cross-sectional morphology of the membrane was observed via scanning electron microscopy. The addition of nonsolvent additives improved the large-cavity structure of the membrane. When the additive was low-content NBA (1–3 wt %), the membrane pore structure transformed from large-cavity structure to fully sponge-like structure. When the content of additive NBA was 3 wt %, the flux of the prepared UF membrane was 130.45 L (m⁻² h⁻¹), the rejection of PEG20000 was 95.54% and the flux remained high at 4 bar in long-term stability test. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47525.     

Dynamic Modeling and Analysis of a Star-wheel Reducer

Forschung im Ingenieurwesen - The star-wheel reducer has been regarded as a promising alternative solution for industrial power transmission where large transmission ratio and high power...     

基于UG的采煤机防爆盖板三维标注及数控工艺研究

随着三维CAD技术的发展,产品制造信息在三维模型和二维图纸之间的反复传递,严重影响了产品制造信息的正确、快速传递。基于三维产品制造信息技术,以采煤机防爆盖板为例,在UG NX10.0中建立了防爆盖板的三维模型并进行了三维标注,设计了加工工艺路线,规划了数控加工刀具轨迹,进行了加工仿真,验证了数控加工的正确性,在此基础上完成了采煤机防爆盖板的三维工艺式设计。该研究对基于模型定义的数字化设计与制造研究,实现制造业信息化具有重要意义。     

Bio-inspired power control and channel allocation for cellular networks with D2D communications

With the tremendous increment of traffic in the next generation mobile networks, device to device (D2D) communication is proposed to relieve the traffic burden of the base station and improve the overall network capacity. It supports direct communications between devices and could reuse the resources of cellular users (CUs). Despite the advantages, D2D communications bring great challenges in interference management. In this paper, we study the power control and channel allocation problems in three scenarios: (1) one CU and one D2D pair; (2) one CU and multiple D2D pairs; (3) multiple CUs and multiple D2D pairs. The goal is to coordinate the mutual interferences and maximize the overall network capacity. We derive sufficient conditions to guarantee the efficiency of D2D communications in scenarios with one CU and one D2D pair. We propose the bio-inspired PSO-P power control algorithm for the scenarios with one CU and multiple D2D pairs, and the PSO-CP algorithm for the scenarios with multiple CUs and multiple D2D pairs to jointly assign channels and powers. Simulation results show that the proposed algorithms are efficient in improving the overall network capacity.

     

配加预处理脱硫灰对铁矿烧结基础特性的影响

 半干法脱硫灰堆弃处理占用土地且容易造成二次污染,将脱硫灰预处理后替代CaO熔剂配入烧结有望充分利用其中的熔剂组分,实现脱硫灰在钢铁企业的闭路资源化利用。研究了脱硫灰配加焦粉加热分解特性及替代CaO熔剂配加对铁矿粉烧结基础特性的影响。结果表明,配加1%焦粉可以有效提高脱硫灰分解率,减少CaSO₄的生成。随着预处理脱硫灰替代CaO比例的增加,铁矿粉同化温度和黏结相强度呈现先增加后减小的趋势;液相流动性呈现单调增加趋势,当替代比超过40%时,液相流动性形成了流动性很大的“假象”;黏结相微观结构表明,替代比例小于40%时,有利于烧结试样中铁酸钙的生成;综合考虑,最佳的替代比例应小于40%。