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大跨径预应力混凝土连续梁桥施工监控技术研究

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价值工程 2025年第1期44卷 62-64页

作者：查李剑上海同济检测技术有限公司上海201900

桥梁结构理想的几何线形与合理的内力状态不仅与设计有关,而且还依赖于科学合理的施工方法。如何通过施工时的浇筑过程的控制以及结构标高调整来获得预先设计的应力状态和几何线形,是大跨桥梁施工中非常关键的问题。因此,在对大跨度预... 详细信息

桥梁结构理想的几何线形与合理的内力状态不仅与设计有关,而且还依赖于科学合理的施工方法。如何通过施工时的浇筑过程的控制以及结构标高调整来获得预先设计的应力状态和几何线形,是大跨桥梁施工中非常关键的问题。因此,在对大跨度预应力混凝土桥梁施工过程中,为了保障其施工质量及安全性,应采取必要的监控技术对其进行检测。本文以实际工程为例,对监控技术进行总结,为类似大跨度预应力混凝土桥梁施工监控提供借鉴作用。

关键词：预应力混凝土悬臂桥梁施工监控

HOMOMORPHISMS BETWEEN CHEVALLEY gROUPS OF TYPES C_nAND g_2 OVER FINITE FIELDS

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Chinese Annals of Mathematics,Series B 1997年第2期18卷 167-172页

作者： zha JIANgUO Department of Applied Mathematics Tongji UniversityShanghai 200092China

It is known that there exists an isogeny sort of Chevalley groups g (Σ, F) associated to any indecomposable root system Σ and any field F . In this paper the author determines all nontrivial homomorphisms from g(Σ, k) to g(Σ, K) when the root system Σ is of type C n or g 2 , and the fields k and K are finite fields of characteristic p .

关键词： Chevalley group Homomorphism Finite field

基于机器学习筛选猪活体肌内脂肪含量间接选育和构建预测模型的关键性状

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南京农业大学学报 2025年第1期48卷 161-170页

作者：吴建杨文孟孜查成万吴望军南京农业大学动物科技学院江苏南京210095

[目的]本研究旨在探究猪断奶重、屠宰前活体重、背膘厚等性状因素对猪肌内脂肪(intramuscular fat,IMF)含量的影响,确定影响猪IMF含量的关键性状因素。[方法]以805头皮特兰×[杜洛克×(长白×大白)]四元商品猪群为试验对象,记录性别,测... 详细信息

[目的]本研究旨在探究猪断奶重、屠宰前活体重、背膘厚等性状因素对猪肌内脂肪(intramuscular fat,IMF)含量的影响,确定影响猪IMF含量的关键性状因素。[方法]以805头皮特兰×[杜洛克×(长白×大白)]四元商品猪群为试验对象,记录性别,测定初生重、断奶重、屠宰前活体重和IMF含量等14个性状,然后通过相关性分析从14个性状中初步筛选出影响IMF含量的性状因素,再通过随机森林模型评估各性状因素对IMF含量影响的重要性,进一步通过LASSO回归和逐步回归筛选出影响IMF含量的关键性状因素;在此基础上,利用广义线性模型(generalized linear model,gLM)分析关键性状因素不同水平对IMF含量的影响。[结果]相关性分析结果显示,猪IMF含量与断奶重(r=0.13, PgLM分析结果显示,4个活体可测性状对IMF含量均具有显著影响,并且阉公猪平均IMF含量(2.52%)显著高于母猪(2.41%)(Pg组平均IMF含量(2.24%)显著低于其他3组(Pg组的平均IMF含量(2.27%)显著低于115 kg以上组(2.67%)(Pg后,各水平组间平均IMF含量差异不显著(P>0.05)。胸腰椎结合处背膘厚大于26 mm组的平均IMF含量(2.73%)显著高于其他背膘厚组(P0.05)。[结论]本研究通过机器学习确定了性别、断奶重、屠宰前活体重和胸腰椎结合处背膘厚4个与IMF含量显著相关的活体可测定性状,并发现平均IMF含量随着屠宰前活体重和胸腰椎结合处背膘厚的增加呈明显的上升趋势。

关键词：猪肌内脂肪间接选择模型构建机器学习活体可测定性状

geometric Error Identification of gantry-Type CNC Machine Tool Based on Multi-Station Synchronization Laser Tracers

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 150-162页

作者： Jun zha Huijie zhang School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China xi’an Jiaotong University Suzhou Academy Suzhou 215123China

Laser tracers are a three-dimensional coordinate measurement system that are widely used in industrial *** propose a geometric error identification method based on multi-station synchronization laser tracers to enable the rapid and high-precision measurement of geometric errors for gantry-type computer numerical control(CNC)machine *** method also improves on the existing measurement efficiency issues in the single-base station measurement method and multi-base station time-sharing measurement *** consider a three-axis gantry-type CNC machine tool,and the geometric error mathematical model is derived and established based on the combination of screw theory and a topological analysis of the machine kinematic *** four-station laser tracers position and measurement points are realized based on the multi-point positioning principle.A self-calibration algorithm is proposed for the coordinate calibration process of a laser tracer using the Levenberg-Marquardt nonlinear least squares method,and the geometric error is solved using Taylor’s first-order linearization *** experimental results show that the geometric error calculated based on this modeling method is comparable to the results from the Etalon laser *** a volume of 800 mm×1000 mm×350 mm,the maximum differences of the linear,angular,and spatial position errors were 2.0μm,2.7μrad,and 12.0μm,respectively,which verifies the accuracy of the proposed *** research proposes a modeling method for the precise measurement of errors in machine tools,and the applied nature of this study also makes it relevant both to researchers and those in the industrial sector.

关键词： Multi-point positioning Multi-station synchronization CNC machine tool geometric error Error separation

Evasion strategies of a three-player lifeline game

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Science China(Information Sciences) 2018年第11期61卷 144-154页

作者： Fan zhaNg Wenzhong zha School of Automation Beijing Institute of Technology State Key Laboratory of Intelligent Control and Decision of Complex System Information Science Academy China Electronics Technology Group Corporation

This study examines a multi-player pursuit-evasion game, more specifically, a three-player lifeline game in a planar environment, where a single evader is tasked with reaching a lifeline prior to capture. A decomposition method based on an explicit policy is proposed to address the game qualitatively from two main aspects:(1) the evader’s position distribution to guarantee winning the game(i.e., the escape zone),which is based on the premise of knowing the pursuers’ positions initially, and(2) evasion strategies in the escape zone. First, this study decomposes the three-player lifeline game into two two-player sub-games and obtains an analytic expression of the escape zone by constructing a barrier, which is an integration of the solutions of two sub-games. This study then explicitly partitions the escape zone into several regions and derives an evasion strategy for each region. In particular, this study provides a resultant force method for the evader to balance the active goal of reaching the lifeline and the passive goal of avoiding capture. Finally,some examples from a lifeline game involving more than one pursuer are used to verify the effectiveness and scalability of the evasion strategies.

关键词： lifeline game three-player pursuit-evasion game barrier evasion strategy game of kind

Adaptive learning algorithm based on mixture gaussian background

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Journal of Systems Engineering and Electronics 2007年第2期18卷 369-376页

作者： zha Yufei Bi Duyan Signal and Information Processing Lab Engineering Coll. of Air Force Engineering Univ. Xi'an 710038 P. R. China

The key problem of the adaptive mixture background model is that the parameters can adaptively change according to the input data. To address the problem, a new method is proposed. Firstly, the recursive equations are inferred based on the maximum likelihood rule. Secondly, the forgetting factor and learning rate factor are redefined, and their still more general formulations are obtained by analyzing their practical functions. Lastly, the convergence of the proposed algorithm is proved to enable the estimation converge to a local maximum of the data likelihood function according to the stochastic approximation theory. The experiments show that the proposed learning algorithm excels the formers both in converging rate and accuracy.

关键词： Mixture gaussian model Background model, Learning algorithm.

Minimax Q-learning design for H_(∞) control of linear discrete-time systems

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Frontiers of Information Technology & Electronic Engineering 2022年第3期23卷 438-451页

作者： xinxing LI Lele xi Wenzhong zha Zhihong PENg Information Science Academy China Electronics Technology Group CorporationBeijing 100086China School of Automation Beijing Institute of TechnologyBeijing 100081China Peng Cheng Laboratory Shenzhen 518052China

The H_(∞)control method is an effective approach for attenuating the effect of disturbances on practical systems, but it is difficult to obtain the H_(∞)controller due to the nonlinear Hamilton-Jacobi-Isaacs equation, even for linear systems. This study deals with the design of an H_(∞)controller for linear discrete-time systems. To solve the related game algebraic Riccati equation(gARE), a novel model-free minimax Q-learning method is developed, on the basis of an offline policy iteration algorithm, which is shown to be Newton’s method for solving the gARE. The proposed minimax Q-learning method, which employs off-policy reinforcement learning, learns the optimal control policies for the controller and the disturbance online, using only the state samples generated by the implemented behavior policies. Different from existing Q-learning methods, a novel gradient-based policy improvement scheme is proposed. We prove that the minimax Q-learning method converges to the saddle solution under initially admissible control policies and an appropriate positive learning rate, provided that certain persistence of excitation(PE)conditions are satisfied. In addition, the PE conditions can be easily met by choosing appropriate behavior policies containing certain excitation noises, without causing any excitation noise bias. In the simulation study, we apply the proposed minimax Q-learning method to design an H_(∞)load-frequency controller for an electrical power system generator that suffers from load disturbance, and the simulation results indicate that the obtained H_(∞)load-frequency controller has good disturbance rejection performance.

关键词： H_(∞)control Zero-sum dynamic game Reinforcement learning Adaptive dynamic programming Minimax Q-learning Policy iteration

Molecular Dynamics Simulation of Hydrate Decomposition Under Action of Alcohol Inhibitors

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Journal of Harbin Institute of Technology(New Series) 2023年第6期30卷 12-28页

作者： Shuyan Wang Xuqing zha Baoli Shao Jing Wang xi Chen Jiawei Fan School of Petroleum Engineering Northeast Petroleum UniversityDaqing 163318HeilongjiangChina

The molecular dynamics method is used to investigate decomposition of methane hydrate at different temperatures,pressures and concentrations of *** analyzing the parameters of system conformation,mean square displacement and radial distribution function,the decomposition of hydrate in the presence of alcohol inhibitors ethylene glycol and glycerol is *** results show that the hydroxyl groups in alcohol molecules can destroy the cage structure of hydrate,and form hydrogen bonds with nearby water molecules to effectively prevent the reformation of ***,ethylene glycol and glycerol serve as inhibitors of methane hydrate,furthermore,in terms of inhibition effect,glycerol is better than ethylene glycol by comparing rate of hydrate decomposition.

关键词： methane hydrate alcohol inhibitors molecular dynamics simulation decompose

Cystic hepatic echinococcosis with intrabiliary rupture

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Hepatobiliary Surgery and Nutrition 2024年第3期13卷 573-574页

作者： Jianming Ma Qifu Yan zha xi Yun Dan Yucheng Hou Rui Tang general Surgery Department Lhasa People’s HospitalLhasaChina Hepatopancreatobiliary Center Beijing Tsinghua Changgung HospitalSchool of Clinical MedicineTsinghua UniversityBeijingChina

A 43-year-old Tibetan female was brought to the department of general surgery with abdominal *** tomography(CT)scan revealed cystic hepatic echinococcosis in the right liver(Figure 1A).Further magnetic resonance cholangiopancreatography showed that there were cyst-biliary communications at right posterior bile duct,and several hydatid cysts inside common bile duct(Figure 1B,yellow arrow head showed rupture,white arrow heads showed bile duct hydatid cysts).Low confluence of right posterior bile duct to the common hepatic duct suggests biliary *** serum total bilirubin was normal,serum alkaline phosphatase and gamma-glutamyl transpeptidase were elevated mildly with the value of 278 and 107 U/L *** underwent right hemihepatectomy plus choledochoscopic hydatid cysts extraction through right posterior hepatic duct stump(Figure 1C,yellow arrow head showed right posterior bile duct stump,white arrow heads showed bile duct hydatid cysts).To prevent the spread of echinococcosis,we covered the surgical area with hypertonic saline gauze.A large number of hydatid cysts presented inside hepatectomy specimen that mixed with a lot of bile(Figure 1D).Hydatid cyst inside bile duct was removed completely,and postoperative recovery was *** removed all the liver cysts,and no signs of any lesion residue in post-operative image.

关键词： rupture hepatic biliary