检索结果-南通市图书馆

On the Unitriangular Groups over Rational Numbers Field

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2022年第4期38卷 718-734页

作者： Rui GAO Jun LIAO he guo liu Xing Zhong XU School of Mathematics and Statistics Hubei UniversityWuhan 430062P.R.China

Let U(n,Q)be the group of all n×n(upper)unitriangular matrices over rational numbers field *** S be a subset of U(n,Q).In this paper,we prove that S is a subgroup of U(n,Q)if and only if the(i,j)-th entry S;satisfies some condition(see Theorem 3.5).Furthermore,we compute the upper central series and the lower central series for S,and obtain the condition that the upper central series and the lower central series of S coincide.

关键词： Nilpotent groups unitriangular groups central series

Global optimization of process parameters for low-temperature SiN_(x) based on orthogonal experiments

在线全文

学校读者我要写书评

暂无评论

Advances in Manufacturing 2023年第2期11卷 181-190页

作者： Lian-Qiao Yang Chi Zhang Wen-Lei Li guo-he liu Jia-Qi Wu-Ma Jin-Qiang liu Jian-Hua Zhang School of Materials Science and Engineering Shanghai UniversityShanghai200444People's Republic of China Key Laboratory of Advanced Display and System Applications Ministry of EducationShanghai UniversityShanghai200072People's Republic of China Huawei Technologies Co. LtdShanghai200120People's Republic of China

Low-temperature silicon nitride(SiNx)films deposited by plasma-enhanced chemical vapor deposition(PECVD)have huge application potential in the flexible ***,the applicability of SiNx largely depends on the film’s general properties,including flexibility,deposition rate,residual stress,elastic modulus,fracture strain,dielectric constant,refraction index,*** optimization towards specific application by conventional experiment design needs lots of work due to the interaction of muti quality and process ***,an efficient global optimization approach for the process technology was proposed based on the Taguchi orthogonal experiment method considering muti-factor *** of all,the Taguchi orthogonal experiment design and analysis was used to rank the influences of main process parameters on the quality characteristics,including radio frequency(RF)power,pressure,silane flow rate,ammonia flow rate and nitrogen flow ***,the global optimization approach was carried out utilizing the multi-response optimizer considering the combination target of film formation rate,residual stress,dielectric constant,elastic modulus,fracture strain,refractive ***,the optimal solution of the SiNx film was finally obtained and verified.

关键词： Plasma-enhanced chemical vapor deposition(PECVD) Low-temperature silicon nitride(SiNx) Flexible display Taguchi orthogonal experiment Process optimization

Deep learning based water leakage detection for shield tunnel lining

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2024年第6期18卷 887-898页

作者： Shichang liu Xu XU Gwanggil JEON Junxin CheN Ben-guo he College of Computer Science Sichuan UniversityChengdu 610065China School of Computer Science and Engineering Northeastern UniversityShenyang 110004China Department of Embedded Systems Engineering Incheon National UniversityIncheon 22012Korea School of Software Dalian University of TechnologyDalian 116621China Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines Northeastern UniversityShenyang 110819China

Shield tunnel lining is prone to water leakage,which may further bring about corrosion and structural damage to the walls,potentially leading to dangerous *** avoid tedious and inefficient manual inspection,many projects use artificial intelligence(Al)to detect cracks and water leakage.A novel method for water leakage inspection in shield tunnel lining that utilizes deep learning is introduced in this *** proposal includes a ConvNeXt-S backbone,deconvolutional-feature pyramid network(D-FPN),spatial attention module(SPAM).and a detection *** can extract representative features of leaking areas to aid inspection *** further improve the model's robustness,we innovatively use an inversed low-light enhancement method to convert normally illuminated images to low light ones and introduce them into the training *** experiments are performed,achieving the average precision(AP)score of 56.8%,which outperforms previous work by a margin of 5.7%.Visualization illustrations also support our method's practical effectiveness.

关键词： water leakage detection deep learning deconvolutional-feature pyramid spatial attention

Prediction of bedload transport inside vegetation canopies with natural morphology

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2024年第3期36卷 556-569页

作者： Li he Yu-qi Shan Chao liu Hui Cao Xing-nian liu Yakun guo State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu610065China Institute for Disaster Management and Reconstruction Sichuan UniversityChengdu610065China China Yangtze Power Co. Ltd.Yichang443002China Hubei Key Laboratory of Intelligent Yangtze and Hydroelectric Science Yichang443002China Faculty of Engineering and Informatics University of BradfordBradfordUK

Due to vegetation drag and vegetation-generated turbulence,bedload transport in vegetated channels is more complicated than that in nonvegetated *** is challenging to obtain accurate predictions of bedload transport in vegetated *** studies generally used rigid circular cylinders to simulate vegetation,and the impact of plant morphology on bedload transport was typically ignored;these methods deviate from natural scenarios,resulting in prediction errors in transport rates of more than an order of *** study measured bedload transport rates inside ***,*** and *** canopies and in arrays of rigid cylinders for *** impact of plant morphology on bedload transport in vegetated channels was *** the canopies of natural morphology,the primary factor driving bedload transport is the near-bed turbulent kinetic energy(TKE),which consists of both bed-generated and vegetation-generated turbulence.A method was proposed to predict the near-bed TKE inside canopies with natural *** the same solid volume fraction of plants,the transport rate inside canopies with a natural morphology is greater than or equal to that within an array of rigid cylinders,depending on the plant *** finding indicates that plant morphology has a significant impact on transport rates in vegetated regions and cannot be ignored,which is typical in *** classic bedload transport equations(the Meyer-Peter-Müller,Einstein,Engelund and Dou equations),which are suitable for bare channels(no vegetation),were modified in terms of the near-bed *** predicted near-bed TKE was inserted into these four equations to predict the transport rate in canopies with natural morphology.A comparison of the predictions indicated that the Meyer-Peter-Müller equation had the highest accuracy in predicting the transport rate in vegetated landscapes.

关键词： Vegetated landscapes turbulent kinetic energy(TKE) bedload transport plant morphology predictive methods

Wellbore-heat-transfer-model-based optimization and control for cooling downhole drilling fluid

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2024年第3期21卷 1955-1968页

作者： Chao Wang he liu guo-Wei Yu Chen Yu Xian-Ming liu Peng Huang Yangtze University Jingzhou434023HubeiChina State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing2249China CNPC Bohai Drilling Engineering Co. LtdTianjin300280China Exploration Development and Construction Engineering Division of PetroChina Jidong Oilfield Company Tangshan63200HebeiChin henan University of Urban Construction Pingdingshan467036HenanChina

To address the two critical issues of evaluating the necessity of implementing cooling techniques and achieving real-time temperature control of drilling fluids underground in the current drilling fluid cooling technology,we first established a temperature and pressure coupled downhole heat transfer model,which can be used in both water-based and oil-based drilling ***,fourteen factors,which could affect wellbore temperature,were *** on the standard deviation of the downhole temperature corresponding to each influencing factor,the influence of each factor was *** influencing factors that can be used to guide the drilling fluid's cooling technology were drilling fluid thermal conductivity,drilling fluid heat capacity,drilling fluid density,drill strings rotation speed,pump rate,viscosity,ROP,and injection *** nondominated sorting genetic algorithm was used to optimize these six parameters,but the optimization process took 182 *** these eight parameters'influence rules with the nondominated sorting genetic algorithm can reduce the optimization time to 108 ***,the downhole temperature has been demonstrated to increase with the inlet temperature increasing linearly under quasi-steady *** this law and PID,the downhole temperature can be controlled,which can reduce the energy for cooling the surface drilling fluid and can ensure the downhole temperature reaches the set value as soon as possible.

关键词： Drilling Cooling Influencing factors Analysis Optimization Control

Review on frost resistance and anti-clogging of pervious concrete

在线全文

学校读者我要写书评

暂无评论

Journal of Traffic and Transportation Engineering(English Edition) 2024年第3期11卷 481-496页

作者： Zhuo Wang Zhichen liu Feng Zeng Kun he Shuaicheng guo China Railway Construction Group Co. Ltd.Beijing 100040China State Key Laboratory of Bridge Safety and Resilience College of Civil EngineeringHunan UniversityChangsha 410082China

Pervious concrete is a special type of concrete that is of high porosity and contains no or a small amount of fine aggregate,and it is an important basic material for sponge city *** presence of a large number of connected pores inside pervious concrete leads to a marked difference in durability failure mechanism compared with that of ordinary *** this study,the frost resistance and anti-clogging of pervious concrete were introduced in detail,and the methods to improve their performance were summarized *** cracking pattern of pervious concrete is influenced by geometric characteristics and three-dimensional morphological features of pores,resulting in its crack generation,development,and geometry being significantly different from those of ordinary concrete,thus leading to different freeze-thaw cycle *** addition,due to its different pore structure compared to ordinary concrete,three types of clogging mechanisms,affecting the long-term permeability of pervious concrete were elaborated systematically(i.e.,physical clogging,biological clogging,and chemical clogging).And the ways to improve the anti-clogging of pervious concrete are systematically presented from multiple ***,in order to broaden the engineering applications of pervious concrete,some research proposals are presented in this study.

关键词： Pervious concrete Connected pore Frost resistance Clogging mechanism

Molecular investigation into the transformation of recalcitrant dissolved organic sulfur in refinery sour water during stripping process

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第3期21卷 2112-2119页

作者： Yu-guo Li Chen he Chun-Mao Chen Fan liu Quan Shi State Key Laboratory of heavy Oil Processing China University of PetroleumBeijing 102249China State Key Laboratory of Coal Mining and Clean Utilization Beijing 100013China PetroChina Ningxia Petrochemical Company Yinchuan 750021NingxiaChina

Refinery sour water primarily originates from the tops of towers in various units and coker condensate,and cannot be discharged directly to a wastewater treatment plant due to high levels of chemical oxygen demand(COD)and organic sulfur *** after the recovery of H_(2)S from the sour water by the stripping process,the effluent still contains a high concentration of dissolved organic sulfur(DOS),which can have a huge bad *** chemical composition of dissolved organic matter(DOM)in refinery wastewater has been extensively studied,the investigation of recalcitrant DOS from sour waters remains *** the present study,chemical composition of sour water DOMs(especially DOS)was investigated using fluorescence spectroscopy(excitation-emission matrix,EEM)and mass spectrometry,including gas chromatography-mass spectrometry(GC-MS)and high-resolution Orbitrap *** GC-MS and EEM results showed that volatile and low-aromaticity compounds were effectively removed during the stripping process,while compounds with high hydrophilicity and humification degree were found to be more *** Orbitrap MS results showed that weak-polar oxygenated sulfur compounds were easier to be removed than oxygenated ***,the effluent still contained significant amounts of sulfur-containing compounds with multiple sulfur atoms,particularly in the form of highly unsaturated and aromatic *** Orbitrap MS/MS results of CHOS-containing compounds from the effluent indicate that the sulfur atoms may exist as sulfonates,disulfide bonds,*** the composition and structure of sour water DOS is crucial for the development of effective treatment processes that can target polysulfide compounds and minimize their impact on the environment.

关键词： Molecular transformation Dissolved organic sulfur Stripping process Refinery sourwater Orbitrap MS

Simulation of Ultrasonic Propagation in Transformers within Thermal Fields and Intelligent Methodology for Hot-spot Temperature Recognition

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electrical Engineering 2024年第1期10卷 35-47页

作者： Dongxin he Dechao Yang Xinhua guo Jiefeng liu Haoxin guo Qingquan Li Gilbert Teyssedre School of Electrical Engineering Shandong UniversityJinan 250061China School of Mechanical and Electronic Engineering Wuhan University of TechnologyWuhan 430070China School of Electrical Engineering Guangxi UniversityGuangxi 530004China UPS INPTCNRSLAPLACE(Laboratoire Plasma et Conversion d’Energie)University of ToulouseToulouse 31100France

Hot-spot temperature of transformer windings is a crucial indicator of internal ***,current methods for measuring the hot-spot temperature of transformers do not apply to those already in operation and suffer from data *** study introduces a novel inversion method that combines ultrasonic sensing technology,multiphysics simulation,and the K-nearest neighbors *** the penetrative ability and temperature sensitivity of ultrasonic sensing,a detailed physical field simulation model was *** study extensively investigates the characteristics of ultrasonic wave signals inside *** investigation includes different temperature fields,ranging from 40℃ to 110℃ at 10℃ intervals,and various ultrasonic wave emitter *** extracting the key features of the acoustic signals,such as the peak time,propagation time,and peak amplitude,an accurate inversion of the winding hot-spot temperature is successfully *** results demonstrate that this method achieves a high accuracy rate(98.57%)in inverting the internal winding hot-spot temperatures of transformers,offering an efficient and reliable new approach for measuring winding hot-spot temperatures.

关键词： Ultrasonic temperature measurement non-destructive testing oil-immersed transformers machine learning

MADRL-based UAV swarm non-cooperative game under incomplete information

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第6期37卷 293-306页

作者： Ershen WANG Fan liu Chen HONG Jing guo Lin ZHAO Jian XUE Ning he School of Electronic and Information Engineering Shenyang Aerospace UniversityShenyang 110136China College of Robotics Beijing Union UniversityBeijing 100101China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China College of Smart City Beijing Union UniversityBeijing 100101China

Unmanned Aerial Vehicles(UAVs)play increasing important role in modern *** this paper,considering the incomplete observation information of individual UAV in complex combat environment,we put forward an UAV swarm non-cooperative game model based on Multi-Agent Deep Reinforcement Learning(MADRL),where the state space and action space are constructed to adapt the real features of UAV swarm air-to-air *** multi-agent particle environment is employed to generate an UAV combat scene with continuous observation *** recently popular MADRL methods are compared extensively in the UAV swarm noncooperative game model,the results indicate that the performance of Multi-Agent Soft Actor-Critic(MASAC)is better than that of other MADRL methods by a large *** swarm employing MASAC can learn more effective policies,and obtain much higher hit rate and win *** under different swarm sizes and UAV physical parameters are also performed,which implies that MASAC owns a well generalization ***,the practicability and convergence of MASAC are addressed by investigating the loss value of Q-value networks with respect to individual UAV,the results demonstrate that MASAC is of good practicability and the Nash equilibrium of the UAV swarm non-cooperative game under incomplete information can be reached.

关键词： UAV swarm Reinforcement learning Deep learning Multi-agent Non-cooperative game Nash equilibrium