Cost an Arm and a Leg

Whatever is said to cost an arm and a leg is very expensive. "It cost me an arm and a leg to get my car repaired." "George flew to Austria to go skiing. He said that the trip cost him an arm and a leg."Cost an Arm and a Leg@张良     

Wind turbine fault detection based on SCADA data analysis using ANN

Wind energy is one of the fast growing sources of power production currently, and there is a great demand to reduce the cost of operation and maintenance. Most wind farms have installed supervisory control and data acquisition （SCADA） systems for system control and logging data. However, the collected data are not used effectively. This paper proposes a fault detection method for main bearing wind turbine based on existing SCADA data using an artificial neural network （ANN）. The ANN model for the normal behavior is established, and the difference between theoretical and actual values of the parameters is then calculated. Thus the early stage of main bearing fault can be identified to let the operator have sufficient time to make more informed decisions for maintenance.     

Optimal operation of multi-storage tank multi-source system based on storage policy

A two-stage method is developed to solve a new class of multi-storage tank multi-source （MTMS） systems. In the first stage, the optimal storage policy of each tank is determined according to the electricity tariff, and the ground-level storage tank is modeled as a node. In the second stage, the genetic algorithm, combined with a repairing scheme, is applied to solve the pump scheduling problem. The objective of the pump scheduling problem is to ensure that the required volume is adequately provided by the pumps while minimizing the operation cost （energy cost and treatment cost）. The decision variables are the settings of the pumps and speed ratio of variable-speed pumps at time steps of the total operational time horizon. A mixed coding methodology is developed according to the characteristics of the decision variables. Daily operation cost savings of approximately 11% are obtained by application of the proposed method to a pressure zone of S. Y. water distribution system （WDS）, China.     

一个改进的多播路由算法

Multicasting is a communication service that allows an application to efficiently transmit copies of data packets to a set of destination nodes. The problem of finding a minimum cost multicast tree can be formulated as a minimum Steiner tree problem in networks, which is NP-completeness. MPH (minimum path cost heuristic) algorithm is a famous solution to this problem. In this paper,we present a novel solution TPMPH (two phase minimum path cost heuristic) to improve the MPH by generating the nodes and the edges of multicast tree separately. The cost of multicast tree generated by the proposed algorithm with the same time as MPH is no more than that of MPH in the worst case. Extensive simulation results show that TPMPH can effectively improve the performance on MPH, and performs better in large-scale networks and wireless networks.     

Weighted time-based global hierarchical path planning in dynamic environment

A weighted time-based global hierarchical path planning method is proposed to obtain the global optimal path from the starting point to the destination with time optimal control. First, the grid- or graph-based modeling is performed and the environment is divided into a set of grids or nodes. Then two time-based features of time interval and time cost are presented. The time intervals for each grid are built, during each interval the condition of the grid remains stable, and a time cost of passing through the grid is defined and assigned to each interval. Furthermore, the weight is introduced for taking both time and distance into consideration, and thus a sequence ofmultiscale paths with total time cost can be achieved. Experimental results show that the proposed method can handle the complex dynamic environment, obtain the global time optimal path and has the potential to be applied to the autonomous robot naviga- tion and traffic environment.     

Scheduling of household power consumption for Step and Time-of-Use tariff system

This paper proposes a hybrid optimization to solve the scheduling of household power consumption for Step and Time-of-Use (TOU) tariff system. The target function is the cost of electricity, and the optimization object is total instantaneous power within a billing period. The control variables are starting moments of each household appliance. The optimization procedure is divided into two stages. Firstly, the prerequisite for minimal cost is calculated through mathematical analysis and generalized function theory. Secondly, the solution is obtained by using a heuristic algorithm in which the result of the first stage is considered to reduce the searching space. And an evaluation methodology is deduced to evaluate the optimization. The computer simulation demonstrates that the proposed approach can reduce the cost of electricity evidently in the sense of probability. The approach shows great value for embedded applications.     

Mother＇s Love

Mothers are always kind to their children and take good care of them. So does my mother.
My mother is a good mother. She looks after me well. She is strict with me. When I do something wrong, she will angry①. But I know she loves me very much.
Last week, I had a bad headache. I felt very terrible. My mother was worried with ② me and took me to the doctor＇s at once. After going home, she asked me to take medicine and cooked delicious food with me. She asked me to stay in bed and brought the food to me. At that moment, I felt her deep love and there were tears in my eyes.
My mother is such a strict teacher and nice friend of mine. She is the greatest mother in the world. I love her with my heart!     

Optimal operating policy for a controllable queueing model with a fuzzy environment

We construct the membership functions of the fuzzy objective values of a controllable queueing model, in which cost elements, arrival rate and service rate are all fuzzy numbers. Based on Zadeh＇s extension principle, a set of parametric nonlinear programs is developed to find the upper and lower bounds of the minimal average total cost per unit time at the possibility level. The membership functions of the minimal average total cost are further constructed using different values of the possibility level. A numerical example is solved successfully to illustrate the validity of the proposed approach. Because the object value is expressed and governed by the membership functions, the optimization problem in a fuzzy environment for the controllable queueing models is represented more accurately and analytical results are more useful for system designers and practitioners.     

Realtime vision-based surface defect inspection of steel balls

In the proposed system for online inspection of steel balls, a diffuse illumination is developed to enhance defect appearances and produce high quality images. To fully view the entire sphere, a novel unfolding method is put forward based on geometrical analysis, which only requires one-dimensional movement of the balls and a pair of cameras to capture images from different directions. Moreover, a realtime inspection algorithm is customized to improve both accuracy and efficiency. The precision and recall of the sample set were 87.7% and 98%, respectively. The average time cost on image processing and analysis for a steel ball was 47 ms, and the total time cost was less than 200 ms plus the cost of image acquisition and balls’ movement. The system can sort 18 000 balls per hour with a spatial resolution higher than 0.01 mm.     

别秋赋

Introduction: As a British Consultant Engineer currently working for a large American engineering company in Yantai, China, specialising in Quality, it is somewhat surprising for me to find myself referred to as a poet it is even more incredible to have my poems published. My interests in life are travel and photography, both of which give me the opportunity to enjoy the diversity of life and cultures around the world.     

Nonlinear Dynamic Reliability of Coupled Stay Cables and Bridge Tower

Nonlinear vibration can cause serious problems in long span cable-stayed bridges.When the internal resonance threshold is reached between the excitation frequency and natural frequency,large amplitudes occur in the cable.Based on the current situation of lacking corresponding constraint criteria,a model was presented for analyzing the dynamic reliability of coupling oscillation between the cable and tower in a cable-stayed bridge.First of all,in the case of cable sag,the d'Alembert principle is applied to studying the nonlinear dynamic behavior of the structure,and resonance failure interval of parametric oscillation is calculated accordingly.Then the dynamic reliability model is set up using the JC method.An application of this model has been developed for the preliminary design of one cable-stayed bridge located on Hai River in Tianjin,and time histories analysis as well as reliability indexes have been obtained.When frequency ratio between the cable and tower is approaching 1∶2,the reliability index is 0.98,indicating high failure probability.And this is consistent with theoretical derivation and experimental results in reference.This model,which is capable of computing the reliability index of resonance failure,provides theoretical basis for the establishment of corresponding rule.     

桥联琐谈

桥联是指桥上的对联,镌刻在石桥桥孔两侧石柱外侧的醒目位置,可供桥下行舟之人观赏。通过对湖州现存古代石桥的考察,笔者发现,桥联的大量出现是在清代乾隆以后,其内容大多为描写景物、劝人向善、记述造桥功德、指明地理位置等。桥联体现了一个时代的中国文学、书法艺术、建筑技术水平,是中国古桥文化的重要内容。     

Strengthening an in-service reinforcement concrete bridge with prestressed CFRP bars

Carbon fiber reinforced polymer(CFRP)bars were prestressed for the structural strengthening of 8 T-shaped rein-forced concrete (RC)beams of a 21-year-old bridge in China.The ultimate bearing capacity of the existing bridge after retrofit was discussed on the basis of concrete structures theory.The flexural strengths of RC beams strengthened with CFRP bars were controlled by the failure of concrete in compression and a prestressing method was applied in the retrofit.The field construction processes of strengthening with CFRP bars-including grouting cracks,cutting groove,grouting epoxy and embedding CFRP bars,surface treating,banding with the U-type CFRP sheets,releasing external prestressed steel tendons-were introduced in detail.In order to evaluate the effectiveness of this strengthening method,field tests using vehicles as live load were applied before and after the retrofit.The test results of deflection and concrete strain of the T-shaped beams with and without strengthening show that the capacity of the repaired bridge,including the bending strength and stiffness,is enhanced.The measurements of crack width also indicate that this strengthening method can enhance the durability of bridges.Therefore,the proposed strengthening technology is feasible and effective.     

Development of the applicability of simplified Henry’s method for skewed multicell box-girder bridges under traffic loading conditions

Concrete precast multicell box-girder (MCB) bridges combine aesthetics with torsional stiffness perfectly. Previous analytical studies indicate that currently available specifications are unable to consider the effect of the twisting moment (torsional moment) on bridge actions. In straight bridges the effect of torsion is negligible and the transverse reinforced design is governed by other requirements. However, in the case of skewed bridges the effect of the twisting moment should be considered. Therefore, an in-depth study was performed on 90 concrete MCB bridges with skew angles ranging from 0° to 60°. For each girder the bridge actions were determined under the American Association of State Highway and Transportation Officials (AASHTO) live load conditions. The analytical results show that torsional stiffness and live load positions greatly affected the bridges?? responses. In addition, based on a statistical analysis of the obtained results, several skew correction factors are proposed to improve the precision of the simplified Henry??s method, which is widely used by bridge engineers to predict bridge actions. The relationship between the bending moment and secondary moments was also investigated and it was concluded that all secondary actions increase with an increase in skewness.     

钢筋混凝土桥梁的耐久性分析

对我国桥梁耐久性现状进行总结,分析了钢筋混凝土桥梁失效的主要模式,指出桥梁防水失效是导致桥梁病害发生的最直接诱因,提出设计要贯彻整体性防水的理念,重视结构的细部防水,从选材、设计与施工、维护各个环节着手来提高钢筋混凝土桥梁的耐久性。     

斜拉桥索梁锚固区足尺疲劳试验研究

斜拉桥索梁锚固区焊接集中,受力复杂,特别是在运营阶段循环应力作用下的疲劳性能值得关注。本文根据国内某大型斜拉桥中索梁锚固区构造,制作1∶1的索梁锚固区试验模型,进行静力与疲劳试验。根据试验实测数据,研究锚固区关键部位的静力及疲劳受力性能,从而对实桥索梁锚固区结构的可靠性做出评价。     

大跨度斜拉桥拉索安全评估的概率方法

为了对运营期斜拉桥安全性进行评估,提出了评估斜拉索安全性的方法.考虑Daniels效应和断丝概率提出斜拉索强度模型与基于斜拉索运营期安全系数的大跨度斜拉桥可靠度评估方法.作为模型的应用验证,分析了宁波招宝山斜拉桥最长边索,即第25号索在不同检测期的安全性,并调查了不同的参数对安全概率的影响.分析结果表明:斜拉索Daniels效应不可忽略;运营期斜拉索的退化可以通过线性增长的索内断丝率来模拟;考虑斜拉桥拉索退化过程的随机性评估运营期斜拉桥拉索安全水平的方法是有效的.     

多点激励下多跨斜拉桥缩尺模型的地震响应研究．部分1：振动台试验

研究目的：创新要点：为多塔斜拉桥在一致激励和非一致激励下地震响应的研究提供地震模拟振动台全桥试验方法,并有助于加强多塔斜拉桥抗震性能和抗震设计的认识。1．建立了地震模拟振动台多台阵试验方法,并首次将其应用于多塔斜拉桥全桥比例缩尺模型的地震响应分析之中;2．通过地震模拟振动台试验,揭示了多塔斜拉桥在多点一致激励和多点非一致激励的地震响应特性并提出了多塔斜拉桥在强震下的破坏模式。研究方法：1．基于动力相似理论,设计与制作了多塔斜拉桥的全桥比例缩尺模型（图2）;2．利用地震模拟振动台多台阵试验,根据在不同地震波作用下和考虑行波效应后多塔斜拉桥模型的主梁和主塔响应,分析了多塔斜拉桥在多点一致激励和多点非一致激励的地震响应特性（图5～图8）;3．根据在地震波不同强度作用下多塔斜拉桥模型的主梁和主塔响虚,分析了多塔斜拉桥在强震下的破坏模式和地震响应（图9）。重要结论：1．江心波作用下该多塔斜拉桥的地震响应大于其他三种地震波;2．多塔斜拉桥在抗震设计时需要考虑行波效应的影响;3．在El-Centro波的加速度峰值高达4．0m／s^2时,多塔斜拉桥模型出现了支座破坏。     

Aerodynamic stability of cable-supported bridges using CFRP cables

To gain understanding of the applicability of carbon fiber reinforced polymer (CFRP) cable in cable-supported bridges, based on the Runyang Bridge and Jinsha Bridge, a suspension bridge using CFRP cables and a cable-stayed bridge using CFRP stay cables are designed, in which the cable’s cross-sectional area is determined by the principle of equivalent axial stiffness. Numerical investigations on the aerodynamic stability of the two bridges are conducted by 3D nonlinear aerodynamic stability analysis. The results showed that as CFRP cables are used in cable-supported bridges, for suspension bridge, its aerodynamic stability is superior to that of the case using steel cables due to the great increase of the torsional frequency; for cable-stayed bridge, its aerodynamic stability is basically the same as that of the case using steel stay cables. Therefore as far as the wind stability is considered, the use of CFRP cables in cable-supported bridges is feasible, and the cable’s cross-sectional area should be deter-mined by the principle of equivalent axial stiffness.     

Several solutions of remote transmission for state monitoring of bridges

1 Introduction 1 The safety and security of bridges have come to be a particular concern by engineers and managers in the recent decades. With the great development of traffic and transportation, a number of highway bridges are expected to be monitored automatically in a monitoring center far from the field. But it is difficult to accomplish the remote monitoring process by conventional methods, in which the state information of bridge have to be collected manually and the data processing done…