Analysis of Pollutant Load Carrying Capacity of the River Tapi Using QUAL2Kw for Surat City

River Tapi is the prime water body for Surat city, Gujarat, India. On a long stretch of 22.39 km in Surat city (Kamrej to Causeway) of the Tapi river, there are many identified and non-identified discharge points available. Excessive discharge from these points restricts the efficiency of the self-purification process which ultimately degrades the river water quality. In this paper, an attempt has been made to estimate the pollutant load-carrying capacity at different segments of the river Tapi using the QUAL2Kw tool. The study has been undertaken with different scenarios: First, the QUAL2Kw model was trained with available river water quality and hydraulic data of the Tapi river in which the complete river segment was divided into 21 reaches. The model was calibrated and validated with the actual concentrations of the pollutants entering. In the second phase, all the point source, non-point source, and headwater characteristics were considered and the pollutant load-carrying capacity of the river in terms of BOD, ISS, and N-nitrate was found. In the third phase, all the sources of pollutants entering the river have been removed and only headwater characteristics were considered for the study. The results indicate that reach no. 21 (21.23ºN, 72.82ºE) has the maximum load-carrying capacity of Biochemical Oxygen Demand (BOD) up to 2057.7 kg/day, Inorganic Suspended Solids (ISS) up to 85633.8 kg/day, and Nitrate (NO3) up to 31688.8 kg/day. However, reach no. 4 has the minimum load carrying capacity of BOD up to 1088.1 kg/day, reach 8 carries a minimum of ISS 205341.6 kg/day and NO3 10215.57 kg/day.

Prediction of Load Carrying Capacity of Corroded Reinforced Concrete Beam

A novel method for prediction of the load carrying capacity of a corroded reinforced concrete beam (CRCB) is presented in the paper. Nine reinforced concrete beams, which had been working in an aggressive environment for more than 10 years, were tested in the laboratory. Comprehensive tests, including flexural test, strength test for corroded concrete and rusty rebar, and pullout test for bond strength between concrete and rebar, were conducted. ne flexural test results of CRCBs reveal that the distribution of surface cracks on the beams shows a fractal behavior. The relationship between the fractal dimensions and mechanical properties of CRCBs is then studied. A prediction model based on artificial neural network (ANN) is established by the use of the fractal dimension as the corrosion index, together with the basic information of the beam. The validity of the prediction model is demonstrated through the experimental data, and satisfactory results are achieved.

Contact Force Distribution and Static Load-carrying Capacity of Large Size Double Row Four-point Contact Ball Bearing

Clearance not only affects the startup torque,rotation precision and stiffness of bearing,but also affects the load distribution,load-carrying capacity and life of bearing.A computational model in which the clearance of bearing is first included is presented for determining the contact force distribution and static load-carrying capacity of a double row four-point contact ball bearing which is subjected to the combined radial,axial and overturning moment loadings.The relation between the negative axial clearance and the contact force distribution is analyzed.The static load-carrying capacity curves are established,and the effects of the changes in negative axial clearance,curvature radius coefficient of raceway groove and initial contact angle on the static load-carrying capacity are analyzed.The results show that,with the increase in the absolute value of negative clearance,the maximum contact load decreases first and then increases.The clearance values in the range of 0.2 mme0 mm have little effect on the static load-carrying capacity of bearing.With the increase in the curvature radius coefficient of raceway groove and the decrease in the initial contact angle,the static load capacity of bearing decreases.

Effect of Weld Parameters on Effective Notch Stress at Weld Root and Toe of Load Carrying Cruciform Joints

Cruciform joints in ships are prone to fatigue damage and the determination of type of weld plays a significant role in thefatigue design of the joint. In this paper, the effect of weld geometry on fatigue failure of load carrying cruciform joints inships is investigated using Effective Notch Stress (ENS) approach. A fictitious notch of 1 mm radius is introduced at theweld root and toe and fatigue stress is evaluated. The effect of weld leg length (l) and weld penetration depth (p) on ENS atweld root and toe are determined. The critical weld leg length (lcr) at which fatigue failure transitions from weld root toweld toe is investigated. An approximation formula for determination of the critical weld leg length considering weldpenetration depth (p) is proposed.

Non-Newtonian Effect of Temperature on Load Carrying Capacity of Thrust Bearings

The influeuce of temperature on rheological characteristics of lubricants is analyzed. The constitutive equation, which describes the non-Newtonian properties of lubricants caused by thermal effect, is founded and coupled with equations or continuity and momentum of fluid to calculate the load carrying capacity of thrust bearings. The results or numerical solution show that lubricants have ultimate shear strength as a result or nou-Newtonian effect of temperature, and the thermal effect plays an.important role in load carrying capacity of thrust bearings The mechanism of film failure in thrust bearings is investigated initially’ Theoretlcal bases for predicting the lubrication situatlon and improving the design of thrust bearings are provided in this paper.

Using a GIS to Assessment the Load-Carrying Capacity of Soil Case of Berhoum Area, Hodna Basin, (Eastern Algeria)

The concept of load-carrying capacity of the soil can be evaluated by two main components: permissible stress and permissible depth;and therefore, running it begins its assessment that allows an outline of exploitation. Nevertheless, the assessment of the load-carrying capacity made the object of several works of research and many models, based on the multi-criteria analysis, have been established. This work examines the contribution of GIS approach to assessment load-carrying capacity of the soil. This one has been finished in two practicums: 1) Assessment of the capacity of soil by a multi-criteria approach, using the Weighted Sum Model (WSM);2) It brought to use the GIS approach to evaluate and spatialize degree of soil bearing stresses resulting from the buildings, as well as load distribution. The method has been applied to the Berhoum area of Hodna Basin, in eastern Algeria, where each is characterized by its various natural properties and density of equipment. Final results are better in the classification of the degree of load-carrying capacity possible in each site. This results in allowing exploiters to program their optimal designs for the rational management of the area.

Comparison Structure Forms Between Isogrid and Orthogrid of C/E Composite Trellis Wound Structure Based on Calculation of Load-Carrying

This paper calculated load-carrying of isogrid and orthogrid of carbon-epoxy composite trellis wound structure(C/E CTWS) using non-linear finite element method.Based on the analysis,test cases were designed and tests of axial compression were carried.Analysis result and test result fit well.In order to be used in the project,this kind of structure cut-out repairing was calculated.The method presented in this paper has been proved and can be used to solve complicated engineering problems.According to calculations and experimental results combined with application,a principle of choosing wound structure is obtained and principle could be applied to engineering.

Shape design of the reinforcement for bending load-carrying capacity of under-matched butt joint under four-point bending load

To improve the bending load-carrying capacity （ BLCC） of under-matched butt joint under four-point bending load in the elastic stage, the shape design of the reinforcement is studied based on the theoretics of mechanics of materials. The concept, criterion, realization condition and design proposal of equal bending load-carrying capacity （EBLCC） are put forward. The theoretical analysis results have been verified by the finite element method. The simulation results are coincident basically with the ones of theoretical analysis. The research results show that the shape design of the reinforcement of EBLCC can improve BLCC of under-matched butt joint and the unilateral-side type reinforcement can replace double-side symmetry

Boundary slippage for generating hydrodynamic load-carrying capacity

Boundary slippage is used to generate the load-carrying capacity of the hydrodynamic contact between two parallel plane surfaces. In the fluid inlet zone, the fluidcontact interfacial shear strength on a stationary surface is set at low to generate boundary slippage there, while in the fluid outlet zone the fluid-contact interfacial shear strength on the stationary surface is set at high enough to prevent the occurrence of boundary slippage. The fluid-contact interfacial shear strength on the entire moving surface is set at high enough to prevent boundary slippage on the moving surface. These hydrodynamic contact configurations are analyzed to generate the pronounced load-carrying capacity. The optimum ratio of the outlet zone width to the inlet zone width for the maximum load-carrying capacity of the whole contact is found to be 0.5.

A Discusion on Limited Load-Carrying Capacity of Rectangular Plates

The elastic-plastic method is often used in designing the inner flat bulkhead plates of submarines, and the upper structure of ships and drilling platforms. Such bulkhead plates can bear the load only once. For the improvement of the load-carrying capacity or the reduction of the weight of plates, the yield line analytical method is employed in this paper to design the bulkhead plate to improve economy and increase the effiective load. Besides, a further sutdy of this method has been made theoretically and experimentally, and the data of the limited load-carrying capacity of the plate have been obtained. Furthermore, the safety coefficients for such a method are presented, which can be used as reference for related departments and staffs.

NEW APPROACHES FOR COMPUTING DYNAMIC LOAD-CARRYING CAPACITY OF MULTIPLE COOPERATING ROBOTIC MANIPULATORS

A novel unified method for computing the dynamic load carrying capacity(DLCC) of multiple cooperating robotic manipulators is developed.In this method,the kinematic constraints and the governing dynamic equations of the multiple robot system are formulated in the joint space by using the method of transference of dependence from one set of generalized coordinates to another,and the virtual work principle,which includes the readily available dynamics and joint torques of individual manipulators,and the dynamic of payload.Based on this dynamic model,the upper limit of the DLCC at any points on a given trajectory is obtained by solving a small size linear programming problem.This method is conceptually straightforward,and it is applicable also to the cases of multi fingered robot hands and multi legged walking machines.

湖南省畜禽养殖粪污的耕地负荷与土地承载力评价

[目的]测算和分析畜禽养殖粪污耕地负荷和土地承载力,为防治农业面源污染,促进农牧协调发展提供科学依据。[方法]根据湖南省畜禽养殖、作物产量等数据资料,在考虑粪污综合利用率的前提下,采用产排污系数法、养分平衡法分别计算2020年各地市州畜禽养殖耕地污染负荷和土地承载力,分析畜禽养殖空间布局以及粪污消纳分配。[结果]湖南省2020年共养殖猪当量4.27×10^(7)头,各区域养殖量差异很大;畜禽粪便和TN,TP耕地负荷分别为19.04t/hm^(2),94.85,24.99kg/hm^(2),耕地负荷警报级别均在Ⅱ级以上,对耕地环境稍有威胁,其中永州市、娄底市、怀化市、郴州市至少有两项耕地负荷警报级别达到了Ⅲ级及以上,耕地环境风险较高;畜禽养殖土地最大承载量为1.23×10^(8)头猪当量,已养殖猪当量仅占其37.18%。各地市州的可增加养殖量也非常可观,常德市、益阳市、岳阳市、邵阳市、长沙市、永州市、衡阳市7个市的可养殖猪当量在5.00×10^(6)头以上。在确认区域内畜禽养殖未超载的基础上,永州市、娄底市、怀化市、郴州市要鼓励林地、园地的作物管理者增加有机肥的施用比例,加大粪污消纳量,才能降低耕地环境污染风险。[结论]湖南省畜禽养殖耕地环境风险整体上较低,畜禽养殖业发展空间很大,但是部分地市州存在耕地污染风险,必须调整粪污消纳去向,才能缓解耕地的粪污消纳压力,推动农业可持续发展。

嵌套加强的LQ550高强冷弯薄壁C型钢连续檩条受力性能研究

为提高LQ550级高强冷弯薄壁C型钢连续檩条的承载能力,采用在支座处嵌套的方法来加强连续檩条。对未加强和采用两种嵌套方式加强的檩条共7组试件进行三点受弯试验,得到了试件的承载性能和破坏形态,试验结果表明加强后的试件出现跨中局部屈曲和嵌套端部局部屈曲两种破坏形态。采用ABAQUS软件建立了非线性有限元模型对嵌套加强的檩条进行数值模拟,有限元分析得到的承载力和破坏形态与试验结果吻合良好,验证了有限元模型的准确性。基于验证的有限元模型,分析了两种嵌套方式和不同嵌套长度对檩条承载力的提升,且表明嵌套檩条的长度宜取为连续檩条跨度的1/5~1/4。

适配变压器全档位切换暂态分析的有载分接开关电路模型构建

有载分接开关(on-loadtap-changer,OLTC)是换流变压器的核心组件,其可靠切换过程关乎换流变的安全。然而目前国内在运特高压换流变用OLTC完全依赖进口,仿真获取OLTC不同运行状态的暂态特性数据是支撑OLTC关键电气参数设计与国产化制造的基础。经典的OLTC模型仅改变变压器变比或仅模拟单级档位切换过程,难以满足全档位电压调整与各级档位暂态特性数据同步获取的需求,导致OLTC设计优化、参数选型及故障分析缺乏足够的仿真数据支持。该文首先以真空OLTC为研究对象建立切换开关和极性开关等效电路模型,根据OLTC复杂的调压功能建立分层控制系统。其次,在PSCAD中搭建交流仿真系统,获取有载调压过程的暂态特性数据波形,与解析计算得到的电压和电流相比误差小于0.2%,证明该模型满足OLTC电磁暂态仿真研究的精度要求。最后,开展循环调压仿真,获得负载电压数据与波形。结果表明:该文提出的OLTC模型能够接收外部控制信号,进行全档位调压与极性转换仿真分析,能够为OLTC的调压研究、故障溯源分析和过渡电阻设计选型等提供基础模型。

震后RC桥墩竖向承载力最优工程需求参数的选取方法

桥墩结构的震后竖向承载力是评估梁式桥梁震后通行功能的重要指标,但其难以测量。为了快速定量地评估桥梁结构的震后通行能力,对评估梁式桥梁结构震后竖向承载力的最优工程需求参数(EDP)进行了系统地研究。首先选取与墩柱残余侧移和损伤相关的5个EDPs,通过对考虑了材料不确定性的RC桥墩进行Pushover分析和动力时程分析得到5个EDPs,进一步对震后的桥墩进行Pushdown分析获取震后竖向承载力。然后采用回归模型对所选EDPs与震后竖向承载力损失比的关系曲线进行回归分析,选取竖向承载力损失比关系曲线的最优回归模型为在ln(x)-y坐标系中的正态累积函数模型,进一步通过最优EDP评价准则对评估竖向承载力损失比的5个EDPs进行评价分析。评价结果表明:当考虑震后可计算性时,峰值侧移率最优;当考虑震后可测性时,残余侧移率最优;当考虑余震时,改进的Park-Ang指标最优。通过选取的最优EDP可以建立桥梁结构功能指标与抗震性能指标之间的联系,为进一步发展和完善桥梁结构的抗震韧性评估和设计提供参考。

钢筋混凝土结构整体承载能力、可靠度和整体抗力系数校准--以简支梁为例

目前,基于构件承载能力极限状态的荷载抗力系数设计法或分项系数法是世界各国土木工程结构设计规范所主要采用的概率极限状态设计方法,目前这两种方法存在两个基本矛盾,需要发展基于结构整体可靠度的整体安全系数设计方法。总结钢筋混凝土结构整体承载力设计值和整体抗力系数的确定方法,将FIB混凝土结构整体抗力系数设计法与结构整体可靠度理论相结合,提出钢筋混凝土结构整体承载能力可靠度和整体抗力系数的校准原理。以双面配筋钢筋混凝土结构简支梁为例,通过非线性有限元分析和蒙特卡洛模拟,校准得到钢筋混凝土简支梁的整体承载能力可靠度和整体抗力系数,研究发现钢筋混凝土简支梁的整体承载力可靠指标总体大于构件承载力可靠指标,且整体可靠度指标和构件可靠度指标均远大于目标可靠度指标,表明《建筑结构可靠性设计统一标准》(GB 50058—2018)的目标可靠度指标有较大提升空间。

海上风电单柱复合筒型基础复合加载条件下的承载特性

为研究新型海上风电单柱复合筒型基础在二维复合加载条件下的承载特性,利用有限元模型计算,首先得到模型在一维荷载空间下的极限承载力,随后通过施加不同的竖向荷载,得到在V-H、V-M、V-H-M荷载空间下的承载能力包络图,并分析不同二维荷载工况下的单柱复合筒型基础各位置处的土压力分布情况以及筒体底部等效塑性应变区的变化情况。结果表明:对于单柱复合筒型基础,在一定范围内,竖向荷载(0~0.15倍竖向极限承载力)的存在能够增大结构的水平及弯矩承载力;在V-H与V-M荷载空间中,基础各位置处的土压力变化、土体等效塑性应变变化具有一定的相似性,可互相对映参考;基础所承受的最大土压力位置与基础受力倾倒方向一致;随着竖向荷载的增加,结构达到极限承载力时,基础底部土体等效塑性应变区的范围与深度相应扩大。

某单箱三室连续梁桥静载试验研究

为测试某单箱三室连续梁桥整体受力特点,检验桥跨结构的承载能力、结构变形是否满足在正常使用状态下的设计要求,通过Midas/Civil对该桥进行有限元分析,并进行了静载试验研究,测试在静载试验下,各控制截面的应变状态和整体挠度,试验结果表明,各控制截面应变与挠度值实测结果与理论结果基本一致,且与之对应的校验系数在规定范围内,该桥强度和刚度均满足设计要求,桥跨结构的承载能力、结构变形在正常使用状态下均符合设计要求;在加载试验前后,对测试截面附近进行了裂缝观测,没有发现新增裂缝,试验桥跨结构承载力满足设计荷载标准要求。

桥梁承载能力多水准可靠度评定方法

为在中国桥梁评定规范中引入“保守设计,非保守评定”的思想,提出一种“新-旧桥”两水准可靠度评定方法.对比分析了中、美桥梁评定规范分析检算公式、评定可靠指标和分项系数的异同,并将美国规范通过折减活载分项系数调整评定可靠度的方法引入中国规范中.首先提出了将新桥设计可靠指标折减0.5作为旧桥评定可靠指标的方法,之后通过一次二阶矩方法对不同受力形式、不同荷载运营状况的评定活载分项系数进行校准,给出了“新桥1.4,旧桥1.2”的评定活载分项系数取值建议,最后通过一个RC简支T梁桥评定算例验证了方法的可行性.结果显示,所提出评定方法与规范方法相比最不利需求能力比降低了0.07,实现了在役旧桥的非保守评定.

冲击载荷下动静压轴承特性变化分析

为研究冲击载荷作用下动静压轴承特性变化,以深腔和浅腔组合的动静压轴承为研究对象,建立动态时变Reynolds方程、膜厚方程、转子动力学方程及边界条件的耦合模型。采用有限差分法和欧拉法计算冲击载荷作用下油膜压力分布等参数,并分析冲击角度、长径比及半径间隙等因素对动静压轴承轴心轨迹、承载力等参数的影响。结果表明:方向相反、幅值相等的冲击载荷使得动静压轴承承载力和轴心轨迹呈现对称变化趋势;动静压轴承长径比越大,冲击载荷下承载力峰值变化越小;半径间隙越小,冲击载荷下承载力峰值变化越小。因此降低半径间隙、提高长径比有利于提升动静压轴承的抗冲击能力。