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Numerical simulation of flow and heat transfer of n-decane in sub-millimeter spiral tube at supercritical pressure

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Chinese Journal of Chemical Engineering 2023年第8期60卷 173-185页

作者： jiahao xing Huaizhi Han Ruitian Yu Wen Luo School of Chemical Engineering Sichuan UniversityChengdu 610065China Engineering Research Center of Combustion and Cooling for Aerospace Power Ministry of EducationSichuan UniversityChengdu 610065China

The flow and heat transfer characteristics of n-decane in the sub-millimeter spiral tube(SMST) at supercritical pressure(p = 3 MPa) are studied by the RNG k-ε numerical model in this paper. The effects of various Reynolds numbers(Re) and structural parameters pitch(s) and spiral diameter(D) are *** indicate that the average Nusselt numberNu and friction factorNu increase with an increase in Re, and decrease with an increase in D/d(tube diameter). In terms of the structural parameter s/d, it is found that as s/d increases, the Nu first increase, and then decrease. and the critical structural parameter is s/d = 4. Compared with the straight tube, the SMST can improve Nu by 34.8% at best, while it can improve Nu by 102.1% at most. In addition, a comprehensive heat transfer coefficient is applied to analyze the thermodynamic properties of SMST. With the optimal structural parameters of D/d = 6 and s/d = 4, the comprehensive heat transfer factor of supercritical pressure hydrocarbon fuel in the SMST can reach 1.074. At last, correlations of the average Nusselt number and friction factor are developed to predict the flow and heat transfer of n-decane at supercritical pressure.

关键词： Sub-millimeter spiral tube Supercritical pressure Numerical simulation Heat transfer performance

Aerial-ground collaborative routing with time constraints

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Chinese Journal of Aeronautics 2023年第2期36卷 270-283页

作者： jiahao xing Lichen SU Wenjing HONG Lu TONG Renli LYU Wenbo DU School of Electronics and Information Engineering Beihang UniversityBeijing 100091China School of Future Aerospace Technology/Shen Yuan Honors College Beihang UniversityBejing 100091China School of Automation Science and Electrical Engineering Beihang UniversityBejing 100091China Guangdong Provincial Key Laboratory of Brain-Inspired Intelligent Computation Shenzhen 518055China Department of Computer Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Research Institute of Frontier Science Beihang UniversityBeijing 100083China CAAC Key Laboratory of General Aviation Operation Civil Aviation Management Institute of ChinaBeijing 100102China

The advancement of autonomous technology makes electric-powered drones an excellent choice for flexible logistics services at the last mile delivery *** reach a balance between green transportation and competitive edge,the collaborative routing of drones in the air and trucks on the ground is increasingly invested in the next generation of delivery,where it is particularly reasonable to consider customer time windows and time-dependent travel times as two typical time-related factors in daily *** this paper,we propose the Vehicle Routing Problem with Drones under Time constraints(VRPD-T)and focus on the time constraints involved in realistic scenarios during the delivery.A mixed-integer linear programming model has been developed to minimize the total delivery completion ***,to overcome the limitations of standard solvers in handling large-scale complex issues,a space-time hybrid heuristic-based algorithm has been developed to effectively identify a high-quality *** numerical results produced from randomly generated instances demonstrate the effectiveness of the proposed algorithm.

关键词： Aerial-ground collaborative delivery Mixed-integer programming Space-time hybrid heuristic algorithm Vehicle routing problem with drones Time-dependent travel times

CM弹塑性本构模型在FLAC^(3D)中的二次开发

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宁波大学学报（理工版） 2024年第2期37卷 36-47页

作者：邢嘉豪熊勇林宁波大学土木工程与地理环境学院浙江宁波315211

显式有限差分程序FLAC3D由于自带的本构库多样性不足,无法统一描述超固结和结构性这两种自然界土体典型力学特性的本构模型.为了扩大FLAC^(3D)应用范围,更精确地模拟土体力学特性,本文基于其自带的二次开发平台,使用C++语言对交变移动(C... 详细信息

显式有限差分程序FLAC3D由于自带的本构库多样性不足,无法统一描述超固结和结构性这两种自然界土体典型力学特性的本构模型.为了扩大FLAC^(3D)应用范围,更精确地模拟土体力学特性,本文基于其自带的二次开发平台,使用C++语言对交变移动(Cyclic Mobility,CM)弹塑性本构模型进行二次开发.首先推导该模型的基本公式;然后介绍FLAC^(3D)的工作原理和关键开发步骤;再通过不同应力路径下的测试,对比FLAC3D模拟值和该本构的理论值,验证开发的正确性;最后通过对一维固结试验数据、三轴排水压缩试验数据和不排水三轴循环加载试验数据的模拟,验证了二次开发模型能较好地模拟土体的力学行为.

关键词：超固结结构性 FLAC3D 弹塑性本构模型

减数拔牙后正畸治疗中断情况下牙齿漂移的研究

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口腔疾病防治 2023年第10期31卷 727-732页

作者：邢嘉豪陈华陈敏陈金东窦昭婧杨欣季骏南京大学医学院附属口腔医院·南京市口腔医院正畸科江苏南京210018 泰州市第四人民医院口腔科江苏泰州225300

目的比较不同类型患者减数拔牙后正畸治疗中断1.5月(45 d)后牙齿漂移的程度。方法本研究已通过单位伦理委员会审查批准,并获得患者知情同意。选取已拔双侧前磨牙但因故未按时进行粘接托槽治疗的84例患者为研究对象。对患者的口腔上下颌... 详细信息

目的比较不同类型患者减数拔牙后正畸治疗中断1.5月(45 d)后牙齿漂移的程度。方法本研究已通过单位伦理委员会审查批准,并获得患者知情同意。选取已拔双侧前磨牙但因故未按时进行粘接托槽治疗的84例患者为研究对象。对患者的口腔上下颌模型进行三维扫描、重建和测量,根据患者的拔牙牙位(第一前磨牙或第二前磨牙)、颌骨类型(上颌或下颌)、垂直骨面型(均角、高角或低角)将其分为12组,应用多因素方差分析减数拔牙之后治疗中断1.5月情况下以下5项指标的变化,包括前牙拥挤度、尖牙间宽度、磨牙间宽度、拔牙间隙、前牙覆。结果拔牙牙位、颌骨类型、垂直骨面型对减数拔牙后1.5个月拔牙间隙的减小量、前牙拥挤度的减小量有影响(P<0.001),拔牙牙位和垂直骨面型对前牙覆增加量有影响(P<0.001)。拔除第一前磨牙的患者相对于拔除第二前磨牙的患者双侧邻牙的漂移明显(P<0.001),上颌双侧邻牙漂移较下颌明显(P<0.001),高角的患者较均角及低角的患者双侧邻牙漂移量明显(P<0.001)。结论对于正畸患者,如果存在上颌减数、第一前磨牙减数、垂直骨面型为高角的情况,拔牙双侧邻牙容易漂移,应该在减数拔牙后及时正畸治疗,并且注意支抗的控制。

关键词：生理性漂移口腔正畸学减数第一前磨牙第二前磨牙垂直骨面型数字化口内扫描三维成像

Partial Surface Damper to Suppress Vibration for Thin Walled Plate Milling

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Chinese Journal of Mechanical Engineering 2017年第3期30卷 632-643页

作者： jiahao SHI Qinghua SONG Zhanqiang LIU xing AI key laboratory of high efficiency and clean mechanical manufacture of ministry of education shandong universityJinan 250061China school of mechanical engineering shandong universityJinan 250061China

The material removal rate and required work- piece surface quality of thin-walled structure milling are greatly limited due to its severe vibration, which is directly associated with the dynamic characteristics of the system. Therefore, the suppression of vibration is an unavoidable problem during milling. A novel partial surface damping method is proposed to modify the mode of the thin walled cantilever plate and to suppress vibration during milling. Based on classical plate theory, the design criterion is analyzed and configuration of the partial surface damper is introduced, in which viscoelastic plate and constraining plate are attached to the surface of the plate to increase the system＇s natural frequency and loss factor. In order to obtain the energy expression of the cutting system, the Ritz method is used to describe the unknown displacements. Then, with Lagrange＇s equation, the natural frequency and loss factor are calculated. In addition, the plate is divided into a finite number of square elements, and the regulation of treated position is studied based on theoretic and experimental analysis. The milling tests are conducted to verify its damping performance and the experimentalresults show that with treatment of partial surface damper, the deformation of the hare plate is reduced from 0.27 mm to 0.1 mm, while the vibration amplitude of the bare plate is reduced from 0.08 mm to 0.01 mm. The proposed research provides the instruction to design partial surface damper.

关键词： Partial surface damper Milling process Thin-walled plate

A novel stability prediction approach for thin-walled component milling considering material removing process

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Chinese Journal of Aeronautics 2017年第5期30卷 1789-1798页

作者： jiahao SHI Qinghua SONG Zhanqiang LIU xing AI Key Laboratory of High Efficiency and Clean Mechanical Manufacture Ministry of Education Shandong University Ji'nan 250061 China School of Mechanical Engineering Shandong University Ji'nan 250061 China

The milling stability of thin-walled components is an important issue in the aviation manufacturing industry, which greatly limits the removal rate of a workpiece. However, for a thin-walled workpiece, the dynamic characteristics vary at different positions. In addition, the removed part also has influence on determining the modal parameters of the workpiece. Thus,the milling stability is also time-variant. In this work, in order to investigate the time variation of a workpiece＇s dynamic characteristics, a new computational model is firstly derived by dividing the workpiece into a removed part and a remaining part with the Ritz method. Then, an updated frequency response function is obtained by Lagrange＇s equation and the corresponding modal parameters are extracted. Finally, multi-mode stability lobes are plotted by the different quadrature method and its accuracy is verified by experiments. The proposed method improves the computational efficiency to predict the time-varying characteristics of a thin-walled workpiece.

关键词： Material removal effect Multi-mode Stability Thin-walled workpiece Vibration

Recent developments on catalytic membrane for gas cleaning

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Chinese Journal of Chemical Engineering 2019年第6期27卷 1391-1402页

作者： jiahao Chen Zhaoxiang Zhong Yongsheng Xia Xuebin Ke Weihong xing State Key Laboratory of Materials-Oriented Chemical Engineering National Engineering Research Center for Special Separation MembraneNanjing Tech UniversityNanjing 210009China Faculty of Science and Engineering School of Engineering and Computer ScienceUniversity of HullHU67RXUnited Kingdom

Catalytic membrane, a novel membrane separation technology that combines catalysis and separation, exhibits significant potential in gas purification such as formaldehyde, toluene and nitrogen oxides(NO_x). The catalytic membrane can remove solid particles through membrane separation and degrade gaseous pollutants to clean gas via a catalytic reaction to achieve green emissions. In this review, we discussed the recent developments of catalytic membranes from two aspects: preparation of catalytic membrane and its application in gas *** membranes are divided into organic catalytic membranes and inorganic catalytic membranes depending on the substrate materials. The organic catalytic membranes which are used for low temperature operation(less than 300 °C) are prepared by modifying the polymers or doping catalytic components into the polymers through coating, grafting, or in situ growth of catalysts on polymeric membrane. Inorganic catalytic membranes are used at higher temperature(higher than 500 °C). The catalyst and inorganic membrane can be integrated through conventional deposition methods, such as chemical(physical) vapor deposition and wet chemical deposition. The application progress of catalytic membrane is focused on purifying indoor air and industrial exhaust to remove formaldehyde, toluene, NO_x and PM2.5, which are also summarized. Perspectives on the future developments of the catalytic membranes are provided in terms of material manufacturing and process optimization.

关键词： Catalytic membranes Gas cleaning Membrane Catalysts

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羊肉风味基料的工艺优化及风味分析

肉类研究 2023年第5期37卷 57-65页

作者：刘慧邢佳浩范敏王梦松潘琳魏超昆宁夏大学食品与葡萄酒学院宁夏食品微生物应用技术与安全控制重点实验室宁夏银川750000

以羊骨粉为原料,通过美拉德反应制备羊肉风味基料。采用二次酶解法对羊骨粉进行酶解后外加L-半胱氨酸、L-谷氨酸、D-木糖和葡萄糖进行美拉德反应,以褐变度、感官评价和色差为指标研究不同反应条件(反应温度、加热时间和初始pH值)对美拉... 详细信息

以羊骨粉为原料,通过美拉德反应制备羊肉风味基料。采用二次酶解法对羊骨粉进行酶解后外加L-半胱氨酸、L-谷氨酸、D-木糖和葡萄糖进行美拉德反应,以褐变度、感官评价和色差为指标研究不同反应条件(反应温度、加热时间和初始pH值)对美拉德反应的影响,结合响应面试验优化羊肉风味基料的加工工艺,采用固相微萃取-气相色谱-质谱联用分析挥发性成分。结果表明:最佳生产工艺为2 g/100 mLL-半胱氨酸、3 g/100 mLL-谷氨酸、2 g/100 mLD-木糖和1 g/100 mL葡萄糖,反应温度110℃、加热时间50 min、初始pH 6.0;共鉴定出51种挥发性物质,其中醛类14种、醇类7种、酮类6种、酸类7种、酯类3种、醚类1种、烃类7种、含硫化合物3种、杂环类3种;能使羊肉风味基料产生肉香味的主要物质有(E)-2-辛烯醛、1-辛烯-3-醇、(E)-2-壬烯醛和(E,E)-2,4-癸二烯醛。

关键词：羊骨粉酶解美拉德反应羊肉风味基料固相微萃取-气相色谱-质谱联用

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枸杞叶黄酮对多种淀粉理化性质的影响

食品安全导刊 2022年第6期 42-45,49页

作者：崔欣阳邢佳浩王睿思马利杨超范艳丽宁夏大学食品与葡萄酒学院宁夏银川750021

本文采用有机溶剂浸提法提取枸杞叶中的黄酮类化合物,通过研究添加不同浓度枸杞叶黄酮后淀粉透明度、凝沉性、流变特性和微观结构的变化,探究枸杞叶黄酮对淀粉理化特性的影响。结果表明,黄酮对糊化过程具有一定抑制作用,使淀粉糊化进程... 详细信息

本文采用有机溶剂浸提法提取枸杞叶中的黄酮类化合物,通过研究添加不同浓度枸杞叶黄酮后淀粉透明度、凝沉性、流变特性和微观结构的变化,探究枸杞叶黄酮对淀粉理化特性的影响。结果表明,黄酮对糊化过程具有一定抑制作用,使淀粉糊化进程减慢,但能加速淀粉老化。本研究为开发枸杞叶黄酮功能性食品奠定了基础且提供了理论依据。

关键词：枸杞叶黄酮淀粉理化特性

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