A Vertical Two-Dimensional Model to Simulate TidalHydrodynamics in A Branched Estuary

A vertical (laterally averaged) two-dimensional hydrodynamic model is developed for tides, tidal current, and salinity in a branched estuarine system. The governing equations are solved with the hydrostatic pressure distribution assumption and the Boussinesq approximation. An explicit scheme is employed to solve the continuity equations. The momentum and mass balance equations are solved implicitly in the Cartesian coordinate system. The tributaries are governed by the same dynamic equations. A control volume at the junctions is designed to conserve mass and volume transport in the finite difference schemes, based on the physical principle of continuum medium of fluid. Predictions by the developed model are compared with the analytic solutions of steady wind-driven circulatory flow and tidal flow. The model results for the velocities and water surface elevations coincide with analytic results. The model is then applied to the Tanshui River estuarine system. Detailed model calibration and verification have been conducted with measured water surface elevations, tidal current, and salinity distributions. The overall performance of the model is in qualitative agreement with the available field data. The calibrated and verified numerical model has been used to quantify the tidal prism and flushing rate in the Tanshui River-Tahan Stream, Hsintien Stream, and Keelung River.

Gear Rattle Analysis of Manual Transmission Based on a Branched Model

A branched model was established to reproduce the vehicle creeping status and illustrate the mechanism for severe rattle phenomena of a 5-speed manual transmission in this paper.Firstly,a quasi-transient engine model was founded and the effective output torque with the crankshaft angle changing was achieved.Then,the time-varying stiffness of loaded gear pairs was obtained,which was calculated by both bending and shearing deformation stiffnesses through finite element result regression analysis and the contact deformation stiffness through the empirical formula.Finally,the branched model of powertrain system considering LuG re tire property and differential characteristics was established to predict the vehicle creeping status and rattle phenomenon of unloaded gear pairs in consideration of detailed drag torque model,and it would make a solid theoretical basis for further research on gear rattle mechanism and vehicle experiments.

PREDICTION OF THE RHEOLOGICAL PROPERTIES OF STAR—TYPE BRANCHED POLYMER SOLUTIONS BY MEANS OF THE FIXED SPECTRUM MODEL

The Rouse-Zimm model with slippage was improved and the basic parameters of modelwere modified to explain the rheological properties of star-type branched polymersolutions. The theoretical results show good agreement with experimental data.

Use River Pollutant Modeling to Simulate and Predict the Change in the Damietta Branch Water Quality before and after Construction of the Ethiopian Dam

This research was conducted on the Damietta branch of the Nile River, Egypt. The Damietta branch receives pollution loadings from the Omar-Bek drain and two power stations located along the path of the branch. The main objective of this research consisted of comparing between the Damietta branch water quality before and after the Ethiopian Dam is built. This comparison was conducted by using the river pollutant (RP) modeling. First, the actual data and the modeling results were compared in order to prove the efficiency and validity of the RP modeling. Findings from regression analysis yielded a strong positive linear relationship (r = 0.987) between the two results. The modeling results showed that Omar-Bek drain had less impact on the Damietta branch water quality. The results also showed that the effluent discharge from the two power stations affected water quality and aquatic life because large quantities of warm and polluted water discharged back into the Damietta branch. The results also showed that constructing the Ethiopian Renaissance Dam would slightly increase pollutants concentrations in the Damietta branch and that this increase would cause a slight deterioration in water quality.

A branch-and-bound algorithm for discrete multi-factor portfolio optimization model

In this paper, a new branch-and-bound algorithm based on the Lagrangian dual relaxation and continuous relaxation is proposed for discrete multi-factor portfolio selection model with roundlot restriction in financial optimization. This discrete portfolio model is of integer quadratic programming problems. The separable structure of the model is investigated by using Lagrangian relaxation and dual search. Computational results show that the algorithm is capable of solving real-world portfolio problems with data from US stock market and randomly generated test problems with up to 120 securities.

Nonlinear mixed-effects height to crown base and crown length dynamic models using the branch mortality technique for a Korean larch( Larix olgensis ) plantations in northeast China

Korean larch(Larix olgensis)is one of the main tree species for aff orestation and timber production in northeast China.However,its timber quality and growth ability are largely infl uenced by crown size,structure and shape.The majority of crown models are static models based on tree size and stand characteristics from temporary sample plots,but crown dynamic models has seldom been constructed.Therefore,this study aimed to develop height to crown base(HCB)and crown length(CL)dynamic models using the branch mortality technique for a Korean larch plantation.The nonlinear mixed-eff ects model with random eff ects,variance functions and correlation structures,was used to build HCB and CL dynamic models.The data were obtained from 95 sample trees of 19 plots in Meng JiaGang forest farm in Northeast China.The results showed that HCB progressively increases as tree age,tree height growth(HT growth)and diameter at breast height growth(DBH growth).The CL was increased with tree age in 20 years ago,and subsequently stabilized.HT growth,DBH growth stand basal area(BAS)and crown competition factor(CCF)signifi cantly infl uenced HCB and CL.The HCB was positively correlated with BAS,HT growth and DBH growth,but negatively correlated with CCF.The CL was positively correlated with BAS and CCF,but negatively correlated with DBH growth.Model fi tting and validation confi rmed that the mixed-eff ects model considering the stand and tree level random eff ects was accurate and reliable for predicting the HCB and CL dynamics.However,the models involving adding variance functions and time series correlation structure could not completely remove heterogeneity and autocorrelation,and the fi tting precision of the models was reduced.Therefore,from the point of view of application,we should take care to avoid setting up over-complex models.The HCB and CL dynamic models in our study may also be incorporated into stand growth and yield model systems in China.

The Model of "Party Branch +" in Promoting Industrial Poverty Alleviation in Poverty-stricken Mountainous Areas of China: A Case Study of Xundian in Yunnan Province

The integration and development of grass-roots Party organizations and accurate poverty alleviation is the focus in social development in the new period. This is also a new measure explored by the CPC Central Committee in the new historical period to solve rural reform and extricate the poor from poverty,and can effectively enhance the enthusiasm of the masses in poverty alleviation and development work. Xundian Hui and Yi Autonomous County is located in the mountainous area of northeast Yunnan Province. It is one of the 592 national key counties for poverty alleviation and development and one of the 38 continuous development counties in Wumeng Mountain area. Since the implementation of the accurate poverty alleviation strategy,Xundian County insists on getting rid of poverty to grasp the overall situation of county economic and social development,focus on the actual situation of the county people,and conscientiously grasp the key of industrial poverty alleviation. It regards industry as the fundamental driving force to realize poverty alleviation from " blood transfusion" to " blood creation",and innovates the model of " Party branch +" to help the poor out of poverty by industry. It has selected 187 agricultural enterprises( cooperatives,large households) to achieve full coverage of all registered poor households,and achieved remarkable results. It has realized that each poor village has one to two leading industries,and each poor household has one to two industrial income projects,having led 30 500 poor households to increase their average income by more than 1 850 yuan. The final incidence of poverty decreased from 26. 93% in 2014 to 0. 35% at the end of 2017,becoming one of the first counties in Yunnan Province to get rid of poverty. It is also the only county in Yunnan Province that has won the Antipoverty Organization Innovation Award of the State Council. Based on field research and interviews,this paper analyzes and summarizes the specific methods,main achievements,practical experience and popularization and application measures of Xundian County " Party Branch +" to promote industrial poverty alleviation,so as to provide necessary reference for accurate poverty reduction and poverty alleviation in similar mountainous areas of Yunnan Province and other provinces.

新时代农林高职院校样板支部创建的探索与实践——以江苏农林职业技术学院农学园艺学院学生党支部为例

高校学生党支部是高校开展思想政治教育的重要阵地,也是落实立德树人根本任务的重要载体。开展新时代高校党建工作样板支部创建工作,有利于学校以点带面,对标争先,促进基层党组织全面提质,以高质量的党建引领高质量事业发展;有利于发挥党支部的战斗堡垒作用,团结凝聚师生。加强大学生样板党支部建设是高校落实组织育人的典型示范,有利于发挥学生党支部的战斗堡垒作用。以农林高职院校学生党支部为例,结合全国样板支部的培育要求,从样板支部的创建背景出发,提出农林高职院校样板支部的培育创建思路以及可供借鉴的经验启示。

支盘桩加固既有填砂路基深层软土的模型试验研究

高速公路改扩建中既有填砂路基深层软土加固时存在路面结构层和施工场地空间限制的问题。首先,提出使用单盘挤扩支盘桩方案进行地基处理,通过挤扩法成盘于桩顶,以期实现不破除路面结构层的情况下达到设置桩顶承台或托板的效果。其次,利用群桩地基物理模型试验模拟一个桩土单元体研究加固方案的承载过程,通过分析桩体、盘体和土体的力学及变形指标研究支盘桩加固既有填砂路堤的承载表现和土体变形特征,最后,考虑土体参数和桩体尺寸推导了既有填砂路基深层软土支盘桩加固方法的二维简化模型。研究结果表明,软土在恒载下桩体轴力和土压力随时间变化调整,原因在于软土的压缩性和砂土的散粒体属性;桩顶轴力总和与恒载大小近似线性正相关,同时支盘直径越大桩顶轴力总和越大、桩承荷载占比越高,试验发现支盘桩加固法的桩承荷载占比约70%。另外,利用所建二维简化模型进行参数分析发现填砂路基中的最小盘间净距与上覆荷载、填砂内摩擦角、深层软土强度指标和支盘桩几何参数相关。

基于开关流图法的Buck-Boost变换器小信号建模分析

阐述Buck-Boost变换器具有输出纹波低,电压可控等优点,广泛应用于新能源汽车电池发电、直流微电网。建立小信号模型有利于对电路系统主电路的控制和控制回路的设计。分析Buck-Boost变换器,利用开关流图法和信号支路的模型建立变换器的流图,从而推导出变换器的小型号模型。

煤矿“Y”型断层分支底板断裂力学判据及模拟研究

【目的】断层分支作为主断层的一部分普遍存在,不易引起人们重视,但断层分支是引起突水的主要因素之一。【方法】以安徽刘庄煤矿为工程地质背景,在考虑Mohr-Coulomb准则岩体压剪断裂判据基础上,建立断层分支渗流与应力双重影响下的断裂力学灾变模型,分析得出断层分支发生劈裂破坏时的临界水压及断层分支到底板破碎区最小安全距离,研究断层倾角、最小主应力、主断层长度和渗透水压对临界水压及最小安全距离的影响规律和主控影响因素,并模拟分析断层分支在采动影响下塑性区及渗流场的演化特征,开展现场压水试验的验证工作。【结果和结论】结果表明:(1)断层分支倾角越大越易发生突水;最小主应力越大,断层分支裂隙越不容易发生扩展;(2)当主断层倾角为60°且断层分支与主断层夹角为60°时,模拟分析结果显示在工作面推进至断层分支正上方位置时,断层导升通道整体活化贯通;当工作面推过断层分支正上方10 m后,断层分支尖端裂隙与工作面底板破坏带贯通并引起底板突水;(3)通过现场压水试验验证了理论计算的正确性,证实断层分支会造成底板裂隙提前与断层相互贯通,引起工作面出水。研究结果可为煤矿采场底板含此类断层分支时的防水煤柱留设提供一定参考。

一类加工需要额外资源的平行机调度问题的算法设计

给出了一类加工需要额外资源的平行机调度问题的精确算法。针对在平行机上加工的工件,除需要机器资源外,还需要一个单位额外资源的问题,考虑额外资源的种类和数量有限,以给出问题的最优调度使工件的完工时间最小为目标。该问题源于地球观测卫星的数据下载,在智能制造和信息处理等领域亦有广泛应用。给出了该问题的整数规划模型、最优解下界和分支定界算法;给出了一种有效的分支策略以避免重复分支,设计了相应的定界方法以提高算法的收敛速度。通过小规模实例和大量的数值仿真实验,验证了算法的正确性和在不同参数配置下的有效性。

轻简式油茶侧枝夹持振动采摘装置研究

针对油茶树成林后立地条件复杂,采摘机械作业空间小,中、大型机械化采摘作业难等问题,基于油茶侧枝水平夹持振动采摘工作原理,设计一种轻简式油茶果侧枝夹持振动采摘装置。根据振动装置采摘原理与试验相结合的分析方法,建立油茶果振动力学模型,分析对油茶果采摘效果产生影响的主要因素。以树枝直径、激振机构振幅、频率为试验因素,将油茶果采净率和花苞损伤率作为试验指标,开展油茶果振动采摘试验。结果表明,激振机构振动频率对油茶果采净率、花苞损伤率影响均为最显著。当树枝直径为16 mm、激振机构振幅为40 mm、振动频率为16 Hz,对应的油茶果采净率为85.70%,花苞损伤率为4.45%,采摘效果最佳,基本符合采摘要求。

长江口北支上段岸滩侵蚀及保护实施效果分析

受上下游工程、来水来沙影响,长江口北支上段近期岸滩侵蚀后退严重。为揭示北支上段近期演变机理,控制河势变化和保护生态基底,收集2001年以来长江口北支全河道水下地形资料,并开展了2017-2020年工程区段水下地形精细实测,基于水动力数学模型研究了岸滩保护措施合理性,以分形理论评价了保护措施实施后效果。结果表明:(1)长江口北支进口江心洲发育,导致上段“S”形主轴弯曲度加大,加剧了暗沙、江心洲和岸滩动荡;(2)在冲刷最严重的岸滩采用丁坝群加护坎可有效阻止岸滩侵蚀后退;(3)多年水下地形实测和分形理论计算评价,岸滩趋于稳定,生态基底得以恢复。鉴于新江心沙洲发育和岸滩、深槽变化加剧了北支上段演变的复杂性,建议尽快成立综合协调部门,统筹提出满足水利、防洪、供水、航运、生态等多目标需求的综合整治方案。

条带充填绿色开采回收压覆煤炭资源支巷宽度研究

以山西三元煤业3号煤条带充填工作面为工程背景,基于固支梁理论模型,分析了条带充填开采支巷顶板的变形与受力特征;并采用数值模拟方法揭示了循环间隔条带充填开采支巷间的相互作用及支巷围岩的塑性区分布特征,综合理论解析研究结果并结合三元煤业充填工作面实际条件,确定多轮循环间隔条带充填开采支巷的合理宽度为5 m;最后,通过工程实践验证了支巷宽度的合理性,实现了压覆煤炭资源的安全采出,促进了三元煤业的绿色可持续开采。

国家级样板党支部创建视角下公立医院临床科室党支部建设实践探索

在公立医院高质量发展新时代背景下,为充分发挥基层党建在学科发展中的引领作用,切实增强党支部政治功能,以党支部工作成效推动学科乃至医院整体高质量发展,武汉大学中南医院重症医学科党支部结合“全国党建工作样板支部”创建,积极探索党支部建设创新路径,从标准建设、融合创新、社会服务三个方面,大力实施铸魂工程、融创工程、助基工程,逐步形成了独具特色的党支部示范品牌,在党建与业务互融互促方面取得显著成效,充分体现了高质量党建引领高质量发展。

基于各向异性注意力的双分支血管分割模型

血管分割对于血管疾病的诊断和治疗具有重要意义,但由于血管边界模糊、病变血管的形状多变且不同样本之间的差异性较大,因此要求分割模型能够准确地挖掘血管与背景类间的差异性以及血管内部的连通性。提出一种基于中心线约束与各向异性注意力的新型三维血管分割网络CAU-Net。针对血管分割的难点,对基础网络结构ResU-Net进行改进,构建各向异性注意力模块,该模块根据管腔结构特有的空间各向异性,从3个方向提取血管空间各向异性特征,并对特征通道间的相关性进行建模,学习血管的三维空间信息。采用主-辅双分支模型,b-Net对血管进行语义分割,a-Net学习血管中心线的连续性特征,约束b-Net的血管分割结果,保证血管分割结果的完整性。在公开数据集3D-IRCADb-01上的实验结果表明,对于门静脉及肝静脉的分割,CAU-Net分别取得(74.80±8.05)%和(76.14±6.89)%的Dice系数、(54.80±8.09)%和(50.40±5.22)%的NSD系数、(72.43±8.26)%和(70.84±6.05)%的clDice系数、(46.47±12.89)%和(39.19±7.97)%的分支检测率以及(67.08±15.59)%和(61.47±9.32)%的树长检测率。在公开脑血管数据集IXI上进行组件消融实验,模型在验证集上的平均Dice、NSD、clDice、BD和TD分别为(94.11±0.39)%、(96.53±0.37)%、(95.83±0.59)%、(98.64±1.63)%和(95.44±1.22)%,相比于Baseline分别提升了0.92%、0.82%、0.92%、1.11%和1.60%。CAU-Net血管分割模型能够显著提升血管分割的精度和完整度。

创建全国高校样板党支部的实践与启示

目的探讨公立医院建设全国高校样板党支部的实施路径,为创建样板党支部提供借鉴。方法以某院创建“全国高校党建工作样板党支部”为例,分析该院铸魂工程、双融工程、星火工程、生命工程等党建“四大工程”典型做法与成效,总结创建经验。结果强化党支部标准化建设是创建样板党支部的首要前提;突出公立医院功能定位,体现医疗特色,是创建样板党支部的内在要求和关键路径;抓实“四大工程”,形成典型示范模式是创建样板党支部的重要目标。结论公立医院应提高思想认识,把创建样板党支部作为加强基层党组织建设的重要抓手,巩固拓展党支部标准化建设成果,凝练党支部建设亮点,集聚各类创新要素,加快构建载体、主体、要素协同创新平台,提升样板党支部创建质量,形成党建品牌效应,努力把党支部建成坚强战斗堡垒。

“全国党建工作样板支部”创建视角下高校教师党支部建设实践探索

高校教师党支部是加强教师思想政治工作的最基层组织,是高校落实立德树人根本任务的组织保障。本文结合教育部“样板党支部”的创建要求,以全国党建工作样板支部创建工程为例,重点介绍了“三三三”工作法的实施过程及成效。在此基础上提出三点经验与启示:把好“人才培养政治关”,落实立德树人根本任务;把好“学科专业定位关”,服务地方经济发展;把好“发展质量关”,锚定中国特色世界一流建设目标。这对高校基层党组织建设工作有重要借鉴意义。

尖端及气隙联合缺陷下XLPE材料电树枝起始特性及其影响因素研究

交联聚乙烯(XLPE)中内部缺陷是导致电缆中电树枝产生的主要诱因,而电树枝的出现将造成电缆绝缘的整体失效,探寻不同绝缘缺陷特征对电树枝起始的影响规律及机理,可为设计、生产环节中改善电缆绝缘提供理论依据。考虑到凸起及气隙的联合缺陷为电树枝引发的主要诱因,本文搭建了针-电极短电缆实验平台以模拟缺陷下电树枝的引发及生长,并建立了缺陷下电应力物理模型,明确了缺陷模型下各缺陷特征对电树枝起始发展的影响规律。研究表明:XLPE电缆中半导体层缺陷的最大电场分布可采用针-板电极下最大场强Mason模型进行描述;由实验及数值化模型结果分析出缺陷的突刺曲率、微孔压强及材料耐受阈值ΔW_(0)与电树枝起始电压呈正相关,可分别从制造工艺、安装铺设等过程中调控三类缺陷特征,以提高实际工程中XLPE电缆的抗电树枝老化能力。