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Micro segment analysis of supercritical methane thermal-hydraulic performance and pseudo-boiling in a PCHE straight channel

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Petroleum Science 2024年第2期21卷 1275-1289页

作者： Qian li Zi-Jie lin liu Yang Yue Wang Yue li Wei-hua Cai Laboratory of Thermo-Fluid Science and Nuclear Engineering Northeast Electric Power UniversityJilin132000JilinChina School of Energy and Power Engineering Northeast Electric Power UniversityJilin132000JilinChina

The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 *** simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow *** results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were *** calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So hea

关键词： Printed circuit heat exchanger Vaporization Supercritical methane Pseudo-boiling Micro segment analysis

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Role of Vickers ligament in the Pathogenesis of Madelung Deformity

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Current Medical Science 2024年第4期44卷 735-740页

作者： Ge XIONG Wei ZHENG li-hua GONG Department of Hand Surgery Beijing Jishuitan HospitalCapital Medical UniversityBeijing 100035China Department of Pathology Beijing Jishuitan HospitalCapital Medical UniversityBeijing 100035China

Objective The Vickers ligament is thought to hinder the growth of palmar ulnar radius by tethering the lunate to the radius,leading to Madelung *** purpose of this study was to clarify the nature of the Vickers ligament and investigate its pathogenesis in Madelung deformities based on our observation of the Vickers *** All 22 patients(33 wrists)with Madelung deformities treated surgically between 2018 and 2022 were *** diagnosis was confirmed radiographically in all *** three-dimensional computed tomography(3D-CT)data of 16 patients(19 wrists)were *** resonance imaging(MRI)data were available for 9 patients(14 wrists).Wrist arthroscopy was used in 4 *** Vickers ligament was resected and submitted for histopathological examination in 8 *** outcomes,3D-CT,MRI,arthroscopy,surgical findings,and histopathology of the Vickers ligament were *** The 3D-CT revealed that the Vickers ligament originated in the metaphysis and formed a metaphyseal defect at the palmar ulnar *** the sequential MR coronal images,the Vickers ligament could be divided into 3 branches,extending to the lunate,triquetrum and ulnar *** and surgical findings revealed that the nature of the Vickers ligament was the stretched palmar ligament of the *** histopathology results revealed ligamentous tissue and fibrocartilaginous metaplasia with a structure similar to that of the triangular fibrocartilage complex(TFCC).Conclusions The Vickers ligament is not a separate aberrant *** nature of the Vickers ligament is a combination of the stretched TFCC ligament(palmar radioulnar ligament,ulnotriquetral ligament and ulnolunate ligament)and radiolunate *** possible pathogenesis of Madelung deformity might be focal early epiphyseal closure at the middle part of the sigmoid notch,which leads to focal growth retardation of the radius and pulls palmar ligaments proximally to for

关键词： Vickers ligament Madelung deformity pathogenesis computed tomography magnetic resonance imaging

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Solidification crack characteristics and sensitivity of peritectic steel

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Journal of Iron and Steel Research International 2024年第7期31卷 1668-1679页

作者： Ya-qiang li Jian-hua liu Zi-ming Wang Ying-ying li Yang He Xiao-wei li Department of Automotive Engineering Hebei Vocational University of Technology and EngineeringXingtai 054000HebeiChina Hebei Special Vehicle Modification Technology Innovation Center Hebei Vocational University of Technology and EngineeringXingtai 054000HebeiChina Institute of Engineering Technology University of Science and Technology BeijingBeijing 100083China School of Petroleum and Natural Gas Engineering Changzhou UniversityChangzhou 213164JiangsuChina

The characteristics and sensitivity of solidification cracks in peritectic steels were investigated using directional solidifi-cation *** cracks were observed in both hypoperitectic steels(12CrlMoV,15CrMo)and hyper-peritectic steel(20CrMo)during solidification at growth velocities of 15,50,and 80 pm/*** the dendritic boundaries,sulphide precipitates were found,promoting crack *** on the statistical analysis of interdendritic cracks in peritectic steels,the area ratio(RA)of interdendritic cracks in a directional solidification structure was proposed to evaluate the crack sensitivity of peritectic ***,the crack sensitivities of peritectic steels(12CrlMoV,15CrMo,and 20CrMo)were tested,evaluated,and compared with the surface crack rates of three types of steels produced from a steel *** results demonstrated that RA was in good agreement with that of the steel plant,and the crack sensitivity of 12CrlMoV steel was the strongest,followed by that of 15CrMo and 20CrMo ***,RA can be used to evaluate the crack sensitivity of peritectic steel.

关键词： Peritectic steel-Directional solidification Growth velocity Dendritic structure Solidification crack Crack sensitivity

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A method for determining the layout of a yaw system based on the Delphi method and the analytic hierarchy process

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Clean Energy 2024年第4期8卷 49-60页

作者： ShuTing lin Lanxing Lu Peng Zhang hua li School of Mechanical Engineering Sichuan UniversityChengdu 610065China

Wind power technology has been widely used due to its characteristics of environmental protection,sustainability and low *** yaw system plays a vital role in improving the energy capture efficiency of a wind ***,the method of layout determination is lacking in the yaw *** solve this problem,a method that combines the Delphi method and the analytic hierarchy process was proposed in this *** evaluation indexes,including transmission efficiency,ratio range,operating temperature range and others,were identified by screening 18 technical indicators using the Delphi ***,the evaluation system of the yaw system was ***,six configuration schemes were ***’scores of schemes were collected according to the evaluation system and the score matrix of evaluation indexes was *** hierarchical model of the evaluation indexes of the yaw system was established and the comprehensive weight was obtained by using the analytic hierarchy pro*** calculating the comprehensive evaluation score,the comprehensive evaluation result was *** 2Z-X(A)negative mechanism,which achieved the highest score of 0.9227,is the optimal scheme.A new method and specific process are provided for *** research gap in the scheme selection method for yaw systems is filled.

关键词： renewable energy generation wind power yaw system Delphi method analytic hierarchy process

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Subgrain-assisted spontaneous grain refinement in rapid solidification of undercooled melts

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Journal of Materials Science & Technology 2024年第7期174卷 234-248页

作者： Jianbao Zhang Dongpeng hua Dexu Cui Xin li Ke hua Yixuan He Haifeng Wang Yuhong Zhao State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China School of Materials Science and Engineering North University of ChinaTaiyuan 030051China

The grain refinement mechanism for rapid solidification of undercooled melts is still an open problem even after 60 years of on-going *** this work,rapid solidification of undercooled Ni and equi-atomic FeCoNiPd melts was studied and spontaneous grain refinement was found at both low and high *** a detailed electron backscattered diffraction analysis,subgrain-induced grain orien-tation scattering and splitting were found to occur along with the transition from coarse dendrites to fine equiaxed grains at low and high undercooling,respectively,indicating that subgrains play an im-portant role during the formation of fine equiaxed *** this basis,a compromise mechanism of subgrain-assisted spontaneous grain refinement was *** the dendrite re-melting induced thermo-mechanical process and fluid flow induced dendrite deformation occur simultaneously during the post-recalescence stage,stress accumulation would be maximum at both low and high undercooling,thus inducing dynamic recrystallization,during which the formation and rotation of subgrains make the grain orientations scattering and even ***,the grain/subgrain size of undercooled FeCoNiPd ascribing to its unique co-segregation behavior keeps almost invariable from low to high undercooling,indicating that the co-segregation strategy would be effective to inhibit grain growth after rapid solidifi-cation and would be useful in practice.

关键词： Rapid solidification Undercooling Spontaneous grain refinement Grain growth High entropy alloy

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Efficient Dynamic Locomotion of Quadruped Robot via Adaptive Diagonal Gait

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Journal of Bionic Engineering 2024年第1期21卷 126-136页

作者： Jian Bi teng Chen Xuewen Rong Guoteng Zhang Guanglin Lu Jingxuan Cao Han Jiang Yibin li The Center for Robotics School of Control Science and EngineeringShandong UniversityJi Nan 250000China

Quadruped animals in the nature realize high energy efficiency locomotion by automatically changing their gait at different *** by this character,an efficient adaptive diagonal gait locomotion controller is designed for quadruped robot.A unique gait planning method is proposed in this *** the speed of robot varies,the gait cycle time and the proportion of stance and swing phase of each leg are adjusted to form a variety of *** optimal joint torque is calculated by the controller combined with Virtual Model Control(VMC)and Whole-Body Control(WBC)to realize the desired *** gait and step frequency of the robot can automatically adapt to the change of *** experiments are done with a quadruped robot made by our laboratory to verify that the gait can change automatically from slow-trotting to flying-trot during the period when speed is from 0 to 4 m/*** ratio of swing phase is from less than 0.5 to more than 0.5 to realize the running motion with four feet off the *** have shown that the controller can indeed consume less energy when robot runs at a wide range of speeds comparing to the basic controller.

关键词： Quadruped robot Gait transition Adaptive gait Energy efficiency

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Natural rubber latex as a potential additive for water-based drilling fluids

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Petroleum Science 2024年第4期21卷 2677-2687页

作者： Jun Yang Guan-Cheng Jiang Jing-Tian Yi Yin-Bo He li-li Yang teng-Fei Dong Guo-Shuai Wang College of Petroleum Engineering China University of Petroleum (Beijing) National Engineering Research Center of Oil & Gas Drilling and Completion Technology Changqing Drilling General Company CNPC Chuanqing Drilling Engineering Company Limited

The environmental hazards and "carbon footprint" of oil and gas drilling can be significantly reduced by replacing traditional petroleum-based chemical additives with natural materials derived from plants and animals. This paper explored for the first time the interaction mechanism between natural rubber latex(NRL) and bentonite suspensions(BTs) through a series of characterization experiments, as well as the potential applications in water-based drilling fluids(WBDF). The gel viscoelasticity experiments showed that NRL could decrease the consistency coefficient(k) and flow index(n) of BTs, and enhance the shear thinning performance of BTs as pseudo-plastic fluids. In addition, 0.5 w/v% NRL not only increased the critical yield stress and strengthened the structural strength between the bentonite particles, but also facilitated the compatibility of pressure loss and flow efficiency. The evaluation of colloidal stability and WBDF performance indicated that NRL particles could promote the hydration and charge stability on the surface of BTs particles, and optimize the particle size distribution and flow resistance of WBDF under the "intercalation-exfoliation-encapsulation" synergistic interaction. Moreover, NRL can improve the rheological properties of WBDF at high temperatures(ling the pores and cracks of the filter cake, which ultimately reduces the permeability of the cake and the filtration loss of WBDF.

关键词： Natural materials Water-based drilling fluids Natural rubber latex Bentonite suspensions Filtration loss

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Human extracellular matrix(ECM)-like collagen and its bioactivity

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Regenerative Biomaterials 2024年第4期3卷 14-26页

作者： Hui Zhou Wenwei li lixin Pan Tianci Zhu teng Zhou E.Xiao Qiang Wei State Key Laboratory of Polymer Materials and Engineering College of Polymer Science and EngineeringSichuan UniversityChengdu 610065China Hunan Maybio Bio-Pharmaceutical Co. LtdChangsha 410000China

Collagen,the most abundant structural protein in the human extracellular matrix(ECM),provides essential support for tissues and guides tissue *** its widespread use in tissue engineering,there remains uncertainty regarding the optimal selection of collagen ***-derived sources pose challenges such as immunogenicity,while the recombinant system is hindered by diminished *** this study,we hypothesized that human ECM-like collagen(hCol)could offer an alternative for tissue *** this study,a facile platform was provided for generating hCol derived from mesenchymal stem cells with a hierarchical structure and biochemical properties resembling native *** results further demonstrated that hCol could facilitate basal biological behaviors of human adipose-derived stem cells,including viability,proliferation,migration and adipocyte-like ***,it could promote cutaneous wound *** to its high similarity to native collagen and good bioactivity,hCol holds promise as a prospective candidate for in vitro and in vivo applications in tissue engineering.

关键词： extracellular matrix native-like collagen cell-derived matrix hierarchical structure

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Associations of serum D-dimer and glycosylated hemoglobin levels with third-trimester fetal growth restriction in gestational diabetes mellitus

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World Journal of Diabetes 2024年第5期15卷 914-922页

作者： Ying Zhang teng li Chao-Yan Yue Yun liu Department of Laboratory Medicine Obstetrics and Gynecology Hospital of Fudan UniversityShanghai 200011China Department of Interventional Radiology The People’s Hospital of Weifang CityWeifang 261041Shandong ProvinceChina Department of Hematology The People’s Hospital of Weifang CityWeifang 261041Shandong ProvinceChina

BACKGROUND Gestational diabetes mellitus(GDM)is a special type of diabetes that commonly occurs in women during pregnancy and involves impaired glucose tolerance and abnormal glucose metabolism;GDM is diagnosed for the first time during pregnancy and can affect fetal growth and *** To investigate the associations of serum D-dimer(D-D)and glycosylated hemoglobin(HbA1c)levels with third-trimester fetal growth restriction(FGR)in GDM *** The clinical data of 164 pregnant women who were diagnosed with GDM and delivered at the Obstetrics and Gynecology Hospital of Fudan University from January 2021 to January 2023 were analyzed *** these women,63 whose fetuses had FGR were included in the FGR group,and 101 women whose fetuses had normal body weights were included in the normal body weight group(normal group).Fasting venous blood samples were collected from the elbow at 28-30 wk gestation and 1-3 d before delivery to measure serum D-D and HbA1c levels for comparative *** diagnostic value of serum D-D and HbA1c levels for FGR was evaluated by receiver operating characteristic analysis,and the influencing factors of third-trimester FGR in GDM patients were analyzed by logistic *** Serum fasting blood glucose,fasting insulin,D-D and HbA1c levels were significantly greater in the FGR group than in the normal group,while the homeostasis model assessment of insulin resistance values were lower(P<0.05).Regarding the diagnosis of FGR based on serum D-D and HbA1c levels,the areas under the curves(AUCs)were 0.826 and 0.848,the cutoff values were 3.04 mg/L and 5.80%,the sensitivities were 81.0%and 79.4%,and the specificities were 88.1%and 87.1%,*** AUC of serum D-D plus HbA1c levels for diagnosing FGR was 0.928,and the sensitivity and specificity were 84.1%and 91.1%,*** D-D and HbA1c levels were risk factors for third-trimester FGR in GDM patients(P<0.05).CONCLUSION D-D and HbA1c levels can

关键词： Gestational diabetes mellitus D-dimer Hemoglobin Fetal growth restriction Fasting blood glucose

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FPGA-based plasma sterilization device for wound-edge recognition

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Nanotechnology and Precision Engineering 2024年第3期7卷 56-70页

作者： Huijuan Lu Xiaorong Tang Minglei li Xueping Jiang Wenxiang Xiao hua li School of life and Environmental Sciences Guilin University of Electronic TechnologyGuilin 541004People’s Republic of China Guilin URIT MEDICAL Electronic Sales Co. Ltd.Guilin 541004People’s Republic of China

There is a currently a lack of large-area plasma sterilization devices that can intelligently identify the shape of a wound for automatic *** this reason,in this work,a plasma sterilization device with wound-edge recognition was developed using aﬁeld-programmable gate array(FPGA)and a high-performance image-processing platform to realize intelligent and precise sterilization of *** was used to design the mechanical structure of the device,and it was manufactured using 3D *** device used an improvement of the traditional Sobel detection algorithm,which extends the detection of edges in only the x and y directions to eight directions(0○,45○,90○,135○,180○,225○,270○,and 315○),completing the wound-edge detection by adaptive *** device can be controlled according to different shapes of sterilization area to adjust the positioning of a single plasma-jet tube in the horizontal plane for two-dimensional move-ment;the distance between the plasma-jet tube and the surface of the object to be sterilized can be also adjusted in the vertical *** this way,motors are used to move the plasma jet and achieve automatic,efﬁcient,and accurate plasma *** was found that a good sterilization effect could be achieved at both the culture-medium level and the biological-tissue *** ideal sterilization parameters at the culture-medium level were a speed of 2 mm/s and aﬂow rate of 0.6 slm,while at the biological-tissue level,these values were 1 mm/s and 0.6 slm,respectively.

关键词： FPGA Wound-edge recognition Improvement of the Sobel algorithm Plasma Automatic and precise sterilization

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