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Topology Optimization of Two Fluid Heat Transfer Problems for Heat Exchanger Design

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1949-1974页

作者： kun yan Yunyu Wang Jun yan School of Chemical Engineering Dalian University of TechnologyDalian116024China Jianghuai Advanced Technology Center Hefei230000China State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsInternational Research Center for Computational MechanicsDalian University of TechnologyDalian116024China

Topology optimization of thermal-fluid coupling problems has received widespread *** article proposes a novel topology optimization method for laminar two-fluid heat exchanger *** proposed method utilizes an artificial density field to create two permeability interpolation functions that exhibit opposing trends,ensuring separation between the two fluid ***,a Gaussian function is employed to construct an interpolation function for the thermal conductivity ***,a computational program has been developed on the OpenFOAM platform for the topology optimization of two-fluid heat *** program leverages parallel computing,significantly reducing the time required for the topology optimization *** enhance computational speed and reduce the number of constraint conditions,we replaced the conventional pressure drop constraint condition in the optimization problem with a pressure inlet/outlet boundary *** 3D optimization results demonstrate the characteristic features of a surface structure,providing valuable guidance for designing heat exchangers that achieve high heat exchange efficiency while minimizing excessive pressure *** the same time,a new structure appears in large-scale topology optimization,which proves the effectiveness and stability of the topology optimization program written in this paper in large-scale calculation.

关键词： Topology optimization two fluid heat exchanger OpenFOAM large scale

Effect of Ultra-Fast Cooling on Microstructure of Large Section Bars of Bearing Steel

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Journal of Iron and Steel Research International 2009年第5期16卷 61-65,80页

作者： SUN yan-kun WU Di The Transportation Engineering College Civil Aviation University of China Tianjin 300300 China State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

The ultra-fast cooling technology of large section bars and the microstrueture for different cooling patterns were studied by optical microscope, transmission electron microscope and energy spectrometer. The results indicated that the large section bars were passed through the zone of secondary carbide precipitation quickly by ultra-fast cooling technology （UFC） at instantaneous cooling rate of about 200 ℃/s and the finishing cooling temperature was higher than Ms. The lamellar spacing of pearlite decreased and the microhardness increased with decreasing the rereddening temperature. The precipitation of network carbide was restrained when re-reddening temperature was 690 ℃. And fine laminated pearlite was obtained through transformation of pseudopearlition that induced the reduction of the diameter of pearlite grain and refinement of the lamellar spacing of pearlite, so ideal microstructures of promoting spheroidizing annealing were obtained.

关键词： ultra-fast cooling technology pearlite network carbide re-reddening temperature

Biochemical characterization of chitin synthase activity and inhibition in the African malaria mosquito, Anopheles gambiae

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Insect Science 2013年第2期20卷 158-166页

作者： Xin Zhang kun yan Zhu Department of Entomology Kansas State University Manhattan KS 66506 USA

Chitin synthase （CHS） is an important enzyme catalyzing the formation of chitin polymers in all chitin containing organisms and a potential target site for insect pest control. However, our understanding of biochemical properties of insect CHSs has been very limited. We here report enzymatic and inhibitory properties of CHS prepared from the African malaria mosquito, Anopheles gambiae. Our study, which represents the first time to use a nonradioactive method to assay CHS activity in an insect species, determined the optimal conditions for measuring the enzyme activity, including pH, temperature, and concentrations of the substrate uridine diphosphate N-acetyl-D-glucosamine （UDP- GlcNAc） and Mg＋＋. The optimal pH was about 6.5-7.0, and the highest activity was detected at temperatures between 37℃ and 44℃. Dithithreitol is required to prevent melanization of the enzyme extract. CHS activity was enhanced at low concentration of GIcNAc, but inhibited at high concentrations. Proteolytic activation of the activity is significant both in the 500×g supernatant and the 40 000×g pellet. Our study revealed only slight in vitro inhibition ofA. gambiae CHS activity by diflubenzuron and nikkomycin Z at the highest concentration （2.5μmol/L） examined. There was no in vitro inhibition by polyoxin D at any concentration examined. Furthermore, we did not observe any in vivo inhibition of CHS activity by any of these chemicals at any concentration examined. Our results suggest that the inhibition of chitin synthesis by these chemicals is not due to direct inhibition of CHS in A. gambiae.

关键词： Anophele gambiae chitin synthase diflubenzuron enzyme inhibition

RNA interference＂ A powerful tool in entomological research and a novel approach for insect pest management

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Insect Science 2013年第1期20卷 1-3页

作者： kun yan Zhu Department of Entomology Kansas State University Manhattan KS 66506-4004 USA

RNA interference （RNAi） is a highly conserved posttran- scriptional gene regulatory mechanism that controls gene expression at the mRNA level within living cells （Fire et al., 1998; Bell6s, 2010; Zhuang ＆ Hunter, 2012）. RNAi is triggered by small interfering RNA （siRNA）, which is processed by Dicer, an endoribonuclease in the RNase III family, from either exogenous （e.g., infection by a virus or laboratory manipulations） or endogenous （e.g., pre- microRNA） double-stranded RNA （dsRNA）. The siRNAs are short dsRNA fragments of about 20-25 base pairs and carry two base extensions at the 3＇ end of each strand. In the RNAi pathway, siRNAs are incorporated into an RNA-induced silencing complex （RISC） in conjunction with an Argonaute （Ago） multidomain protein. Ago which contains an RNase H-like domain responsible for target degradation cleaves and discards the passenger （sense） strand of the siRNA duplex leading to an active RISC.

关键词： RNA干扰昆虫学双链RNA siRNA Dicer酶工具管理虫害

Rhizosphere bacterial communities and soil nutrient conditions reveal sexual dimorphism of Populus deltoides

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Journal of Forestry Research 2023年第3期34卷 761-771页

作者： Qiliang Zhu kun yan Yufeng Dong yanping Wang Taishan Forest Ecosystem Research Station of State Forestry Administration College of ForestryShandong Agricultural UniversityTai’an 271018People’s Republic of China Shandong Academy of Forest Jinan 250014People’s Republic of China

Sexual dimorphism of plants shapes the diff erent morphology and physiology between males and ***,it is still unclear whether it infl uences belowground ecological *** this study,rhizosphere soil of male and female Populus deltoides and bulk soil were collected from an 18-year plantation(male and female trees mix-planted)and grouped into three soil *** carbon(C),nitrogen(N)and phosphorus(P)levels were determined,and soil bacterial communities were analyzed by high-throughput *** results showed the less total carbon and total organic carbon,the more nutrients(available phosphorus,nitrate nitrogen and ammonium nitrogen)available in the rhizosphere soils of female poplars than soils of ***,α-diversity indices of the rhizosphere bacterial communities under male plants were signifi-cantly *** component analysis showed that the bacterial communities were signifi cantly diff erent between the male and female soil ***,the bacterial co-occurrence network in soil under male trees had more nodes and edges than under *** analysis showed the more functional bacteria taxa related to biofi lm formation and antioxidation under *** results indicate that soils under male poplars had more diverse and more complex co-occurrence networks of the rhizosphere bacterial community than soils under female trees,implying that male poplars might have better environmental *** study provides insight into the diff erent soil-microbe interactions of dioecious *** details about the infl uencing mechanism of sexual dimorphism on rhizosphere soil bacterial communities need to be further studied.

关键词： Dioecious poplar Rhizosphere bacterial community High-throughput sequencing Bacterial function prediction

Robust adaptive compensation control for unmanned autonomous helicopter with input saturation and actuator faults

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Chinese Journal of Aeronautics 2019年第10期32卷 2299-2310页

作者： kun yan Mou CHEN Qingxian WU Ronggang ZHU College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Luoyang Institute of Electro-Optical Equipment of AVIC Luoyang 471000China

This paper studies a robust adaptive compensation Fault Tolerant Control(FTC)for the medium-scale Unmanned Autonomous Helicopter(UAH)in the presence of external disturbances,actuator faults and input *** improve the disturbance rejection capacity of the UAH system in actuator healthy case,an adaptive control method is adopted to cope with the external disturbances and a nominal controller is proposed to stabilize the ***,compensation control inputs are designed to reduce the negative effects derived from actuator faults and input *** on the backstepping control and inner-outer loop control technologies,a robust adaptive FTC scheme is developed to guarantee the tracking errors *** the presented FTC controller,the uniform ultimate boundedness of all closed-loop signals is ensured via Lyapunov stability *** results demonstrate the effectiveness of the proposed control algorithm.

关键词： Compensation control Fault tolerant control Input saturation Tracking control Unmanned autonomous helicopter

Experimental and numerical simulation of bird-strike performance of lattice-material-infilled curved plate

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Chinese Journal of Aeronautics 2021年第8期34卷 245-257页

作者： Jun yan Chenguang ZHANG Sixu HUO Xianghai CHAI Zhihui LIU kun yan State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsDalian University of TechnologyDalian 116024China Ningbo Institute of Dalian University of Technology Ningbo 315016China Department of Discipline Engineering AVIC Commercial Aircraft Engine Co.LTDShanghai 200241China Shanghai Engineering Research Center of Civil Aero Engine Shanghai 200241China School of Chemical Engineering Dalian University of TechnologyDalianLiaoning 116024China

The anti-bird-strike performance of a lattice-material-infilled curved plate is investigated *** automatically filling the curved structure by classical lattice material filling methods will cause a large number of manufacturing defects,a space-dependent lattice material filling method for the curved plate is firstly proposed in this paper Next,using a face-centered cubic lattice,a lattice-material-infilled test piece with a hollow ratio of 40.8%is *** test pieces are manufactured via additive manufacturing using titanium *** bird-strike experimental tests,the test pieces are crashed against gelatin birds at an impact velocity of 200 m/*** strain gauges are used to record the crash history and the results are ***,a numerical analysis to simulate the bird-strike experiment is *** results from the experimental tests and numerical simulation agree *** work shows that the lattice-material-infilled curved plate yields promising bird-strike ***,lattice-infilled materials are feasible for protecting aerospace components against bird-strike as well as for reducing the component weight.

关键词： Bird-strike test Face-centered cubic lattice Infilled curved plate Lattice material Numerical simulation

Assessment of the Performance of WEPP in Purple Soil Area with Simulated Rainfall Experiments

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Journal of Mountain Science 2012年第4期9卷 570-579页

作者： FU Bin WANG Yukuan XU Pei yan kun Key Laboratory of Mountain Hazards and Earth Surface Process ChineseAcademy of SciencesChengdu 610041China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China

The water erosion prediction project （WEPP） model is a popular water erosion prediction tool developed on the basis of the physical processes of water erosion. Although WEPP has been widely used around the world, its application in China is still insufficient. In this study, the performance of WEPP used to estimate the runoff and soil loss on purple soil （Calcaric Regosols in FAO taxonomy） sloping cropland was assessed with the data from runoff plots under simulated rainfall conditions. Based on measured soil properties, runoff and erosion parameters, namely effective hydraulic conductivity, inter-rill erodibility, rill erodibility, and critical shear stress were determined to be 2.68 mm h-1, 5.54 x l0^6 kg s-1 m-4, 0.027 s m-1 and 3-5 Pa, respectively, by using the recommended equations in the WEPP user manual. The simulated results were not good due to the low Nash efficiency of 0.41 for runoff and negative Nash efficiency for soil loss. After the four parameters were calibrated, WEPP performed better for soil loss prediction with a Nash efficiency of 0.76. The different results indicated that the equations recommended by WEPP to calculate parameters such as erodiblity and critical shear stress are not suitable for the purple soil areas, Sichuan Province, China. Although the predicted results can be accepted by optimizing the runoff and erosion parameters, more research related to the determination of erodibility and critical sheer stress must be conducted to improve the application of WEPP in the purple soil areas.

关键词： WEPP Soil erosion Simulated rainfall Purple soil Erodibility

The current application of thermal ablation in colorectal liver metastasis

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Hepatobiliary Surgery and Nutrition 2021年第6期10卷 872-874页

作者： Zhongyi Zhang kun yan Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education/Beijing) Department of UltrasonographyPeking University Cancer Hospital&InstituteBeijingChina

Colorectal liver metastases(CRLM)are one of the most frequent clinical *** the last 20 years,the clinical outcome for patients with CRLM has improved *** resection is the gold standard treatment for resectable CRLM,achieving a 5-year overall survival(OS)rate of 42%(1).However,the majority of patients with CRLM are not candidates for *** the development of thermal ablation,this technique provides an alternative treatment modality by either ablation alone or combined with resection.A recent review by Takahashi et *** the current role of thermal ablation in the management of CRLM(2).

关键词： clinical metastasis Liver