Power Analysis on Deicing and Snow Melting by Electrically Conductive Concrete

The deicing and snow melting methods frequently used and their advantages and disadvantages are analyzed at first, then the working principle on deicing by electrically conductive concrete is introduced. Based on the energy conservation law, the minimum power required for deicing and snow melting is determined. The curve of power output versus voltage of carbon fiber reinforced concrete (CFRC) is measured in laboratory; the experimental results show that the thermal energy produced in CFRC connected to DC power source is enough for deicing and snow melting purpose.     

Numerical Simulation on Whole Construction Process of High-Rise CFST Structures

The time-changing analysis model for concrete filled steel tubes was established based on the time-changing concrete model of CEB-FIP MC90, in which the interaction between steel tube and concrete core was considered by the restraint conditions of master and slave nodes. The numerical simulation method was developed for analyzing the whole construction process of high-rise CFST structures. A real structure was taken as numerical example, in which the influence of concrete creep and shrinkage as well as construction process was considered. The results of numerical simulation are compared with those obtained from on-site monitoring. It is shown that the concrete creep and shrinkage as well as construction process have big influence on high-rise CFST structures, which should be taken into account in designs and constructions.     

Analysis of a New Distributed-Pump Scheme Applied in District Heating Network

It is helpful for energy efftciency to use distributed pumps instead of valves to regulate hydraulic balance in a district heating system (DHS). A new scheme of distributed pump-system is presented based on performance comparison of hydraulic regime and power saving of single-heat-source dendritic pipeline networks with regulating valves and/or distributed pumps. Supposing that the new scheme was employed in multi-sources looped-pipe network, theoretical analysis and case study were carried out to evaluate off-design performances including hydraulic self-regulation, supply water temperature stability and power-saving potential. The results indicated that the proposed scheme would contribute to minimizing power consumption, retarding water temperature change, and would be convenient to adjust the quality and quantity independently in the looped-pipe heat supply networks.     

微波加热技术在冷库融霜中的应用

基于微波的加热特点及能量分析,简述了微波加热的技术特性,探讨了微波加热技术应用于冷库融霜的可行性。介绍了微波加热技术辅助热氨融霜的设计方案,并指出今后微波融霜系统的研究方向。     

Curvature Force Method for Nonlinear Analysis of Prestressed Concrete Frame

In this paper, based on the structure characters and load applying means, a method called as curvature force method is put forward and proved in the nonlinear analysis of bonded prestressed concrete frame. Based on the nonlinear program, the simulation calculation was carried out on test results of two prestressed concrete frames by this method. The results from calculation are identical with the experiment ones. So it may be added to the methods for the nonlinear analysis of prestressed concrete frame.     

欧姆加热过程中苹果浆的电导率及VC降解规律研究

研究了苹果浆的欧姆加热规律及VC的降解动力学,考察了温度和果浆含量对电导率的影响以及电场强度、果浆含量对加热速率的影响。结果表明,苹果浆的电导率随温度的升高而增大,且呈线性关系;随着果浆含量的增加,电导率和加热速率都在增加;随着电场强度的增大,加热速率增加。苹果浆中VC对热不稳定,苹果浆中VC降解符合动力学一级反应,得到的苹果浆中VC的预测模型,经验证与实测值拟合较好,表明该模型是合理的。     

Numerical Analysis of Acoustic Environment with Finite Element Method

The acoustic environment of highway tunnel is complex and has influences on the driving safety and comfort. In case of emergency, evacuation information is difficult to transfer. Finite element method is used for calculating highway tunnel acoustic modal and attenuation characteristics. The results show that acoustic mode of highway tunnel has symmetry in the horizontal pressure amplitude of symmetry regional is equal and phase is the same or opposite. The higher modal frequency, the greater sound pressure amplitude is, and the effect of tunnel length on modal frequency is smaller. Decay curves of pressure level at each point in the highway tunnel over time are nonlinear. After the source excitation, in 1.5 s, attenuation rate is faster than that of few seconds later and the attenuation time of sound pressure level 30 dB is 5.5 to 7 s.     

Discussion on the Hydraulic Calculation Method of Loop Heating Pipe Network

The authors definitely make out the concept of loop main pipeline, supplying main pipeline and ramiform branch line, as well as the order of their hydraulic calculation. Then they puts forward the principia of how to study out the direction of loop main pipeline and presents the method of making flux initial distribution. The matrix of loop main pipeline hydraulic square dispersion is set up. The node referenced pressure is defined and the equation of how to calculate it is deduced. A software is developed to calculate the loop main pipeline hydraulic square dispersion. The method of calculating ramiform branch margin impetus is given.     

Value Engineering Applied in the Bidding

Project bidding and assessing aim at choosing the best bidder, and then achieve the best optimization of bidder's value aim. The current method of project bidding does not qualifiedly describe the connection among the quality, time limit for the project, and investment of engineering project, so it can not exactly evaluate the bidder's value aim. Consequently, this is not beneficial to achieve the best value. Value engineering is a function analysis method achieving the necessary functions at the lowest cost of total lifetime cycle. Based on the analysis of the existing issues in the valuating system, this paper provides some improvement on the current valuating methods and scientific basis for choosing the best bidder through calculating the value coefficient such as function, cost and value.     

Analysis Method for Nonlinear Properties of Reinforced Concrete Columns

Accurate assessment of seismic performance of reinforced concrete columns（RC columns）is significant to ensure the safety of reinforced concrete structure subjected to earthquake action. In order to derive a reasonable prediction by Pushover analysis, a calculation method for determining lateral load-deformation curve, unloading rigidity and reloading rigidity of RC columns subjected to combined flexural and shear force is proposed based on test data analysis in the PEER (Pacific Earthquake Engineering Research Center) Structural Performance Database, and the formula for calculating the equivalent damping ratio according to hysteresis loop area is also provided. In this paper, conventional section analysis techniques are employed for modeling the flexural behavior of lateral load-deformation relationship, and the modified formulas with actual data analysis are implemented for modeling the effect of shear and slip of the longitudinal bars at columns end. Unloading rigidity and reloading rigidity of the columns are determined by statistical analysis on relations between themselves and secant rigidity of the columns respectively. Finally, a single-degree of freedom (SDOF) system is taken as an example to illustrate the applications of the proposed model for developing the corresponding “capacity curve” and performing pushover analysis on columns. The influences of primary parameters, such as shear-span ratio, axial load ratio, reinforcement ratio and stirrup ratio, on seismic performance of columns are also analyzed.     

Construction and Application of DBMS About Concrete Durability

Factors affecting concrete durability are various and complex. And the number of parameters that characterize the status of durability is large. It's not easy to eliminate error from numerous data and find out the internal law among them. However, it's convenient for one database management system to manage and dispose of data so as to evaluate and forecast concrete durability. This paper briefly discusses the virtues of the object-oriented programming-VB6.0 for database and factors resulting in damage of concrete durability, introduces carefully the structure and function of DurDBMS. At the end of the paper, an instance is set up to transact carbonate and the result reveals that the error of prediction meets with request of experiment, quantitative analysis accords with that of qualitative.     

Applied Data Disposal Technology of Numerical Controlled Last Carving Machine

Necessary technical disposal methods of original last data before carving are introduced in turn.First,data interpolation and smoothness are adopted for removing absent dots and bug dots.Afterwards,all sections of last are rotated and central axis is adjusted because measurement axis and machining axis are not the same.Finally,head and tail of last are designed and appended in order to use clamp to fix last during the machining process.     

Resistivity Method for Monitoring the Early Age Pore Structure Evolution of Cement Paste

The changes of electrical resistivity with time of cement pastes with water to cement ratio of 0.23, 0.35 and 0.53 were in situ continuously monitored by using electrodeless resistivity apparatus. Isothermal conduction calorimeter was also used to measure the hydration degree. The quantitative relationship between electrical resistivity evolution of paste and development of pore structure was proposed during hydration process. The results show that four stages (dissolution, induction, acceleration and deceleration) are identified according to the characteristics of electrical resistivity and its differential resistivity curves. In addition, a lower water to cement ratio shows a smaller capillary porosity and constriction factor as well as a higher tortuosity factor, resulting in a higher electrical resistivity of bulk paste, and the reverse phenomenon is observed with the electrical resistivity of pore solution.     

A Three-Dimensional Numerical Model and Experimental Research for U-Tube Ground Heat Exchanger in Heating Operation

In terms of the theory of a transient energy balance on the finite controlled volume, in this paper, a transient three-dimensional heat transfer model for the simulation of a single vertical U-tube ground heat exchanger based on finite-difference methods is systematically proposed. The model is also compared with experimental results during the heating operation in winter. What's more,based on test data and domestic and foreign literature, the equations to determine the undisturbed ground temperature for wet and heavy soil in Chongqing are presented. These formulae are essential conditions to calculate the heat transfer model.     

The Use of UEA Concrete in the Construction of the World Trade Centre in Chongqing

The reasons of cracking of large mass concrete construction in the early age are analysed and the technical thinking and ways of prevention of cracking are presented in this paper.UEA micro_expanding agent was used in the construction of the World Trade Centre of chongqing.The early contraction of corcrete is changed into limited expansion.the practical engineering experience is obtained in efficiently perventing the early cracking of concrete and ensuring the strength of concrete.     

The Essential Procedure of Numerical Simulation for Hydrodynamic in River and Coastal Engineering

Hydrodynamic models have been widely applied to river and coastal engineering projects. Understanding the hydrodynamic process is a prerequisite to modeling the pollution and sediment transport process. Hydrodynamic models of varying degrees of complexity should be selected appropriately according to the object of study, physical properties of the flow domain and hydrodynamic features. The essential procedure of hydrodynamic simulation is described in this paper. The main problems such as selection of model dimension in physical space, choice of variables, boundary conditions, initialization, design of computational grid, model resolution, parameterization of smaller scale fluctuations and sub-grid scale processes, model calibration and verification are investigated.     

Object-oriented Design of Three-Dimensional Numerical Manifold Method

The Object-Oriented technology is introduced into the 3-d Numerical Manifold method(NMM). The design method and management of the Classes about the three dimensional Numerical Manifold Method are studied. The Classes are designed and the prototypes of some key classes are shown. As an example,the 3-d numerical calculation results are given. The calculation results are in good agreement with the theoretical solutions. It shows that the Object-Oriented programming of 3-d NMM is correct.     

Study on Simulation Method of Heating and Air - conditioning Energy Consumption of Residential Buildings

The heating and air conditioning energy consumption of residential buildings is influenced by the behavior of indoor living personnel.On the basis of research and analysis,two kinds of calculation modes reflecting the behavior of indoor living personnel are estimated.Under two kinds of different calculation modes,by using the building thermal environment simulation Toolkit DeST to simulate the energy consumption calculation for certain residential building in Shanghai,and the simulation results are compared with the research results.The influence of calculation mode on heating and air conditioning energy consumption of residential buildings in Shanghai is analyzed in this paper.In order to obtain the right simulation calculation method correctly reflecting the energy consumption of residential buildings.This method can be used for analysis and evaluation of heating and air conditioning energy consumption of residential buildings in Shanghai,and it can serve as instruction for right energy design of residence building.     

Design of Cooling/Heating Floor AC Systems in Residential Buildings

This paper puts forward a new way in air_conditioning,which combines the fresh_air supply unit and such floor radiation system for the dehumidication and cooling in summer or heating in winter. By analyzing its advantages and limitations, it is found that this so called Cooling/Heating Floor AC System can improve the IAQ of residential building while keep high efficiency quality. It is also recommended that an methodology for the HVAC system designing,which will ensure the reduction of energy cost of users.