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Degradation of warm permafrost and talik formation on the qinghai-Tibet Plateau in 2006-2021

Advances in Climate Change Research 2024年第2期15卷 275-284页

作者： qi-hang MEI Ji CHEN You-qian LIU Shou-Hong Zhang Jing-Yi ZHAO Tian-Chun DONG Jun-Cheng WANG Yao-Jun ZHAO Beiluhe Observation and Research Station of Frozen Soil Engineering and Environment Key Laboratory of Cryospheric Science and Frozen Soil EngineeringNorthwest Institute of Eco-Environmental and ResourcesChinese Academy of SciencesLanzhou 730000China China Railway qinghai-Tibet Group Co.Ltd Xining 810007China University of Chinese Academy of Sciences Beijing 100049China

Permafrost is degrading globally,particularly those with low thermal stability on the qinghai-Tibet Plateau,owing to climate ***,the inadequacy of direct research on permafrost degradation based on in-situ monitoring limits the prediction of permafrost degradation and engineering *** study explored the processes and modes of permafrost degradation into talik by analyzing ground temperature data from five points in the hinterland of the qinghai-Tibet Plateau from 2006 to *** results showed that the degradation of the warm permafrost layer with a geothermal gradient of zero occurred simultaneously in the top and bottom *** rate of permafrost degradation from the top down and bottom up increase during the degradation process,but the increase of the former is more drastic after the formation of thawed ***,the construction of the qinghai-Tibet Railway changed the degradation modes of the permafrost in adjacent natural sites through horizontal heat transfer,particularly after through talik formation under the *** findings suggest that taking countermeasures before or immediately after forming thawed interlayer is more *** evaluating the thermal impact of projects in warm permafrost regions,special attention should be given to the horizontal heat transfer process that may result from the formation of a through talik.

关键词： Warm permafrost Degradation Talik qinghai-Tibet Plateau Climate change

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The recirculation flow after different cross-section shaped high-rise buildings with applications to ventilation assessment and drag parameterization

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Building Simulation 2024年第4期17卷 509-524页

作者： Keyi Chen Ziwei Mo Jian hang School of Atmospheric Sciences Sun Yat-sen University&Southern Marine Science and Engineering Guangdong LaboratoryZhuhai519082China Key Laboratory of Tropical Atmosphere-Ocean System Ministry of EducationZhuhai519000China

The building cross-section shape significantly affects the flow characteristics around buildings,especially the recirculation region behind the high-rise *** generic building shapes including square,triangle,octagon,T-shaped,cross-shaped,#-shaped,H-shaped and L-shaped are examined to elucidate their effects on the flow patterns,recirculation length L and areas A using computational fluid dynamics(CFD)simulations with Reynolds-averaged Navier-Stokes(RANS)*** sizes and positions of the vortexes behind the buildings are found to be substantially affected by the building shapes and subsequently changing the recirculation *** recirculation length L is in the range of 1.6b-2.6b with an average of *** maximum L is found for L-shaped building(2.6b)while the shortest behind octagon building(1.6b).The vertical recirculation area Av is in the range of 1.5b^(2)-3.2b^(2)and horizontal area Ah in 0.9b^(2)-2.2b^(2).The L,Av and Ah generally increase with increasing approaching frontal area when the wind direction changes but subject to the dent structures of the#-shaped and cross-shaped *** area-averaged wind velocity ratio(AVR),which is proposed to assess the ventilation performance,is in the range of 0.05 and 0.14,which is around a three-fold difference among the different building *** drag coefficient parameterized by Ah varies significantly,suggesting that previous models without accounting for building shape effect could result in large uncertainty in the drag *** findings provide important reference for improving pedestrian wind environment and shed some light on refining the urban canopy parameterization by considering the building shape effect.

关键词： recirculation region cross-section shape ventilation assessment drag parameterization computational fluid dynamics

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Prognostic prediction model of colorectal cancer based on preoperative serum tumor markers

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World Journal of Gastrointestinal Surgery 2024年第5期16卷 1344-1353页

作者： Yu-hang Diao Si-qi Rao Xin-Peng Shu Yong Cheng Can Tan Li-Juan Wang Dong Peng Department of Gastrointestinal Surgery The First Affiliated Hospital of Chongqing Medical UniversityChongqing 400016China

BACKGROUND Preoperative serum tumor markers not only play a role in the auxiliary diagnosis and postoperative monitoring in colorectal cancer(CRC),but also have been found to have potential prognostic *** To analyze whether preoperative serum tumor markers,including carcinoembryonic antigen(CEA)and carbohydrate antigen 19-9(CA19-9),affect the prognosis of *** This was a retrospective study conducted in a single *** with nonmetastatic CRC who underwent initial surgery between January 2011 and January 2020 were enrolled and divided into development site and validation site groups at a ratio of 7:*** independent prognostic factors were screened by Cox regression analysis,and finally,a prognostic nomogram model was *** newly developed model was tested by internal *** Eventually,3526 postoperative patients with nonmetastatic CRC were included in the *** were 2473 patients at the development site and 1056 patients at the validation ***(P<0.01,HR=1.042,95%CI=1.033-1.051),tumor node metastasis(TNM)classification(P<0.01,HR=1.938,95%CI=1.665-2.255),preoperative CEA(P=0.001,HR=1.393,95%CI=1.137-1.707)and CA19-9(P<0.01,HR=1.948,95%CI=1.614-2.438)levels were considered independent prognostic factors for patients with nonmetastatic CRC and were used as variables in the nomogram *** areas under the curve of the development and validation sites were 0.655 and 0.658,*** calibration plot also showed the significant performance of the newly established *** We successfully constructed a nomogram model based on age,TNM stage,preoperative CEA,and CA19-9 levels to evaluate the overall survival of patients with nonmetastatic CRC.

关键词： Colorectal cancer Prognosis Carcinoembryonic antigen Carbohydrate antigen 19-9 Nomogram

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Development of underwater electric manipulator based on interventional autonomous underwater vehicle (AUV)

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第3期25卷 238-250页

作者： Xiaohui HU Jiawang CHEN hang ZHOU Ziqiang REN Ocean cllege Zhejiang UniversityZhoushan 316021China Hainan Institute Zhejiang UniversitySanya 572025China The Engineering Research Center of Oceanic Sensing Technology and Equipment Ministry of EducationZhoushan 316021China

In applications such as marine rescue,marine science,archaeology,and offshore industries,autonomous underwater vehicles(AUVs)are frequently used for survey missions and monitoring tasks,with most operations being performed by manned submersibles or remotely operated vehicles(ROVs)equipped with robotic arms,as they can be operated remotely for days without ***,they require expensive marine vessels and specialist pilots to operate *** exploring oceans are no longer satisfied with the use of manned submersibles and *** is a growing desire for seabed exploration to be performed using smarter,more flexible,and automated *** improving the field operation and intervention capability of AUVs,large-scale and long-range seafloor exploration and sampling can be performed without the support of a mother ship,making it a more effective,economical,convenient,and rapid means of seafloor exploration and sampling operations,and playing a critical role in marine resource *** this study,we explored the integration technology of underwater electric robotic arms and AUVs and designed a new set of electric manipulators suitable for water depths greater than 500 *** reliability of the key components was analyzed by finite element analysis and,based on the theory of robot kinematics and dynamics,simulations were performed to verify the reliability of the key *** were conducted on land and underwater,trajectory tracking experiments were completed,and the experimental data in air and water were compared and ***,the objectives for further research on the autonomous control of the manipulator underwater were proposed.

关键词： Underwater electric manipulator Inverse kinematics Trajectory planning Trajectory tracking accuracy

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Price Masking Strategy of Cross-Border E-Commerce Platform Financing

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Journal of Systems Science & Complexity 2024年第2期37卷 668-691页

作者： LI Jianbin hang Zhouxin CHEN Zhiyuan XIAO Shan School of Management Huazhong University of Science and TechnologyWuhan 430074China School of Economics and Management Wuhan UniversityWuhan 430072China

E-commerce platform financing is a new service pattern of supply chain ***,this pattern may bring some new issues when considering the problem of cash flow shortage and financing difficulties of small and medium-sized *** enterprises use this service,they worry about the leakage of preferential wholesale price when applying the full loan amount and providing the true transaction *** on the model consisting of a supplier,a retailer and a cross-border e-commerce platform,the authors design a price masking strategy to prevent the retailer’s preferential wholesale price information from *** authors analyze the profit of the retailer and the platform before and after adopting the price masking *** authors find that the price masking strategy always benefits the ***,the optimal profit of the retailer and the platform are both affected by the loan interest ***,there exists a range of loan interest rates that can benefit both the retailer and the platform if the price masking strategy is *** research emphasizes that platform can expand the total business volume by allowing retailers to use price masking *** other words,there will be more and more retailers attracted by the strategy,which benefits the long-term growth of cross-border e-commerce platform financing.

关键词： Cross-border e-commerce e-commerce platform financing price masking supply chain finance

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Surface engineering of Li-and Mn-rich layered oxides for superior Li-ion battery

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Tungsten 2024年第1期6卷 259-268页

作者： Lu-Xiang Ma Tian-Dong Chen Chun-Xi Hai Sheng-De Dong Xin He qi Xu hang Feng AXin Ji-Tao Chen Yuan Zhou College of Materials and Chemistry and Chemical Engineering Chengdu University of TechnologyChendu 610000China qinghai Building and Materials Research Co. LtdXining 810000China Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

The Li-and Mn-rich layered oxides(R-LNCM)are considered as promising cathode materials for high-energy density lithium-ion batteries(LIBs).However,the interface side reaction aggravates the voltage and capacity fading between cathode material and electrolyte at high voltage,which severely hinders the practical application of LIB ***,lithium polyacrylate(LiPAA)as the binder and coating agent is applied to suppress the voltage and capacity fading of R-LNCM *** flexible LiPAA layers with high elasticity are capable of impeding cathode cracks on the particle surface via mechanical stress ***,superior voltage and capacity fading suppression on R-LNCM electrode is finally *** a result,LiPAA-R-LNCM cathode exhibits a remarkable specific capacity of 186 mA·h·g^(-1)with~73%retention at 1℃after ***,the corresponding average discharge potential is maintained to~3.1 V with only~0.4 V falling.

关键词： LiPAA interphase layer Interface side reaction Cathode cracks Capacity and voltage fading suppression Liand Mn-rich cathode

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Boron nitride silicone rubber composite foam with low dielectric and high thermal conductivity

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Chinese Journal of Chemical Engineering 2024年第4期68卷 224-230页

作者： Shuilai qiu hang Wu Fukai Chu Lei Song College of Safety and Ocean Engineering China University of Petroleum-BeijingBeijing 102249China State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026China

Silicone rubber(SR)is widely used in the field of electronic packaging because of its low dielectric *** this work,the porosity of the SR was improved,and the dielectric constant of the SR foam was reduced by adding expanded microspheres(EM).Then,the thermal conductivity of the system was improved by combining the modified boron nitride(f-BN).The results showed that after the f-BN was added,the dielectric constant and dielectric loss were much lower than those of pure ***-sized modified boron nitride(f-mBN)improved the dielectric and thermal conductivity of the SR foam better than that of nano-sized modified boron nitride(f-nBN),but f-nBN improved the volume resistivity,tensile strength,and thermal stability of the SR better than *** the mass ratio of f-mBN and fnBN is 2:1,the thermal conductivity of the SR foam reaches the maximum value of 0.808 W·m^(-1)·K^(-1),which is 6.5 times that before the *** heat release rate and fire growth index are the lowest,and the improvement in flame retardancy is mainly attributed to the high thermal stability and physical barrier of f-BN.

关键词： Foam Composites Dielectric properties Thermal conductivity Mechanical properties Flame retardant

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Heterocatalytic ethylene methoxycarbonylation via a pseudo-hydride pathway over Pt_(1)/MoS_(2)

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Science China Chemistry 2024年第8期67卷 2427-2428页

作者： Bo-hang Zhao Bin Zhang Institute of Molecular Plus Department of ChemistrySchool of ScienceTianjin UniversityTianjin 300072China

Ethylene (C2H4) methoxycarbonylation (EMC) with CO and methanol (CH3OH) to methyl propanoate (MP) is industrially important due to its 100% atom efficiency [1].However, the heavy reliance on homogeneous Pd-based catalysts and strong acid media over commercial EMC processes still causes economic and environmental concerns [2]. At present, supported single-atom catalysts (SACs) can serve as bridges for accessing homogeneous catalysts in traditional heterogeneous catalytic processes.

关键词： processes. catalytic hydride

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Reynolds-number scaling analysis on lift generation of a flapping and passive rotating wing with an inhomogeneous mass distribution

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Chinese Journal of Aeronautics 2024年第2期37卷 259-269页

作者： Suyang qiN Haotian hang Yang XIANG Hong LIU J.C.Wu center for aerodynamics school of aeronautics and astronauticsshanghai jiao tong universityshanghai 200240china

Insects usually fly by passively rotating wings,which has been applied to the design of flapping-wing Micro-Air Vehicles(MAVs)to reduce mechanical *** this paper,a robotic passive rotating-wing model is designed to investigate wing kinematics and lift generation,which are measured by a high-speed camera and a force transducer,*** addition,flow fields are measured using the Particle Image Velocimetry(PIV).Experimental results demonstrate that passive rotating motion has a coordinative relationship with actively stroking *** the stroke amplitude or frequency increases,the rotating amplitude is *** characterize the active stroking motion,a driving Reynolds number Redrivingis defined,which varies from 68 to 366 in this *** the gravity center of the wing towards trailing ed ge induces the increase of additional torque M,which decreases the wing rotating amplitude and promotes the advance of wing *** find that the timing of wing rotation is gradually delayed and the mean lift coefficient C^(-)_(L)monotonously decreases as *** increasing the additional torque M,C^(-)_(L)is slightly improved and approaches to the lift coefficient of a real fruit fly at driving Re approximately equal to *** instantaneous lifts combined with the vortical structures further demonstrate that the lift generation associated with wing rotation is mainly attributed to the growth of the LeadingEdge Vortex(LEV)and the passive wake capture *** wake capture is influenced by LEV,reversal stroke motion and wing additional torque together,which can only maintain the lift at a high level for a considerable *** high-lift generation mechanisms of flapping and passive rotating flight could shed light on the simplified design of MAVs and the improvement of their aerodynamic performance.

关键词： Flapping flight Unsteady lift Passive rotation Vortex flow Leading-edge vortex

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Image Segmentation-P300 Selector: A Brain–Computer Interface System for Target Selection

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Computers, Materials & Continua 2024年第5期79卷 2505-2522页

作者： hang Sun Changsheng Li He Zhang Mechanical Engineering Nanjing University of Science and TechnologyNanjing210018China

Brain–computer interface (BCI) systems, such as the P300 speller, enable patients to express intentions withoutnecessitating extensive ***, the complexity of operational instructions and the slow pace of characterspelling pose challenges for some patients. In this paper, an image segmentation P300 selector based on YOLOv7-mask and DeepSORT is proposed. The proposed system utilizes a camera to capture real-world objects forclassification and tracking. By applying predefined stimulation rules and object-specificmasks, the proposed systemtriggers stimuli associated with the objects displayed on the screen, inducing the generation of P300 signals in thepatient’s brain. Its video processing mechanism enables the system to identify the target the patient is focusing oneven if the object is partially obscured, overlapped, moving, or changing in number. The system alters the target’scolor display, thereby conveying the patient’s intentions to caregivers. The data analysis revealed that the selfrecognitionaccuracy of the subjects using this method was between 92% and 100%, and the cross-subject P300recognition precision was 81.9%–92.1%. This means that simple instructions such as “Do not worry, just focuson what you desire” effectively discerned the patient’s intentions using the Image Segmentation-P300 selector. Thisapproach provides cost-effective support and allows patients with communication difficulties to easily express theirneeds.

关键词： Brain-computer interface deep learning electroencephalogram P300 YOLOv7-mask

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