基于ANSYS的MEMS离子源测试用高真空腔设计与分析

设计了一种适用于MEMS离子源测试用的高真空腔体。根据目前质谱测试用高真空腔的相关研究,针对高真空获得能力、保持能力及频繁使用的简便性,综合考虑结构强度、内壁出气等因素,选用了同时满足强度与低出气率的筒型结构。基于ANSYS软件,综合分析了高真空下该腔体的结构稳定性及危险点分布,确定了优化的腔体壁厚选择范围。该研究可为高真空腔体的设计提供理论依据。

Esophageal space-occupying lesion caused by Ascaris lumbricoides

Ascaris lumbricoides is the largest intestinal nematode parasite of man,which can lead to various complications because of its mobility.As the esophagus is not normal habitat of Ascaris,the report of esophageal ascariasis is rare.An old female presented with dysphagia after an intake of several red bean buns and haw jellies.The barium meal examination revealed a spherical defect in the lower esophagus.Esophageal bezoar or esophageal carcinoma was considered at the beginning.The patient fasted,and received fluid replacement treatment as well as some oral drugs such as proton pump inhibitor and sodium bicarbonate.Then upper gastrointestinal endoscopy was done to further confirm the diagnosis and found a live Ascaris lumbricoides in the gastric antrum and two in the duodenal bulb.The conclusive diagnosis was ascariasis.The esophageal space-occupying lesion might be the entangled worm bolus.Anthelmitnic treatment with mebendazole improved patient's clinical manifestations along with normalization of the radiological findings during a 2-wk follow-up.Authors report herein this rare case of Ascaris lumbricoides in the esophagus,emphasizing the importance of awareness of this parasitic infection as it often presents with different and unspecific symptoms.

Experimental and numerical simulation of lignite chemical looping gasification with phosphogypsum as oxygen carrier in a fluidized bed

Phosphogypsum(PG)is a solid waste produced in the wet process of producing phosphoric acid.Lignite is a kind of promising chemical raw material.However,the high sulfur of lignite limits the utilization of lignite as a resource.Based on fluidized bed experiments,the optimal reaction conditions for the production syngas by lignite chemical looping gasification(CLG)with PG as oxygen carrier were studied.The study found that the optimal reaction temperature should not exceed 1123 K;the mole ratio of water vapor to lignite should be about 0.2;the mole ratio of PG oxygen carrier to lignite should be about 0.6.Meanwhile,commercial software Comsol was used to establish a fuel reaction kinetics model.Through computational fluid dynamics(CFD)numerical simulation,the process of reaction in fluidized bed were well captured.The model was based on a two-fluid model and coupled mass transfer,heat transfer and chemical reactions.This study showed that the fluidized bed presents a flow structure in which gas and solid coexist.There was a high temperature zone in the middle and lower parts of the fluidized bed.It could be seen from the results of the flow field simulated that the fluidized bed was beneficial to the progress of the gasification reaction.

基于CFD的在役飞机电接触致热效应计算方法

为了弥补红外热成像技术受可达性限制的不足,精确获取非金属封闭体内电接触部位复杂热流场信息,提出一种基于计算流体力学(computational fluid dynamics,CFD)的在役飞机电接触致热效应计算方法。针对圆柱面接触模型进行结构和数值离散,分析了不同辐射模型对仿真计算结果的影响,认为表面辐射(surface to surface,S2S)模型在得到较好的仿真结果的同时,其迭代所占用的计算资源较少;针对封闭体-电接触模型,采用分段细化-平滑建模及近壁网格处理方法,实现了模型结构的有效离散,得到了致热耦合三维热流场,与红外温度谱的特征相符,通过探究计算流体力学与实验方法结合的技术路径,为电接触可靠性分析及失效预判等实效方法的提出开展有益探索。

Modified corn-core powder for enhancing sludge dewaterability:Synthesis,characterization and sludge dewatering performance

The high water content of sludge has always posed significant challenges for its treatment.Synthetic flocculants,which are widely used in sewage treatment plants,can cause secondary pollution during their production and use.Thus,natural polymer flocculants made of natural materials have received increased research attention recently.Corncore,an agricultural waste,was modified through alkalization with sodium hydroxide(NaOH)and etherification with cetyltrimethylammonium bromide(CTMAB)in this study.The L16(45)orthogonal array was used to study the modification conditions.The moisture content(MC)of treated sludge was reduced by approximately 37%with the addition of modified corncore powder(MCCP),which was synthesized under optimal conditions.In addition,changes in the functional groups of the material before and after modification were determined by FTIR.Thermogravimetric analysis indicated that MCCP was steady at room temperature,moreover,BET analysis showed that MCCP had greater surface area.The microstructures of material before and after modification were examined by scanning electron microscopy,revealing that MCCP had a flakeshaped structure and had an increased area of contact area with sludge particles.MCCP is a dehydrating agent that can enhance sludge dewaterability through charge neutralization and reagglomeration and provide superior economic benefits.