Applying hybrid dynamic substructure synthetic method to dynamic analysis for tower crane

This paper presents a dynamic hybrid substructure synthetic method for tower crane dynamic analysis. This method employs the transfer matrix method and the flexibility degree method respectively to formulate the vibration mathematical models of the tower body and tower top system substructures in the hoisting luffing plane. Based on the motion of the substructures in the interface and the dynamic harmonize condition, the frequency equations are established. Then the program is designed according to the mathematical models and firstly applied to the dynamic analysis of the QTZ63 tower crane in the construction site and the parameter identification of attached device and tower body. The test results show that the value calculated by the above method is quite approximate to the instrument measured value, which can meet the engineering requirements. Further study has found that , for the flexible long-distance attached tower crane, the method that introduces dynamic load coefficient for statics analysis of tower cranes is unprecise enough since there exist errors.This paper suggests to conduct site test and identification of the rigidity coefficient of attached device of the tower crane for the accident prevention of tower crane collapse by timely take measures.     

Dynaical Mathematical Model of String

In the process of oil drilling, drilling string and rock bit are main drilling tools. The fact of their failure would cause serious accidents. To solve this problem, the vibration law of string should be found. The longitudinal vibration model, torsional model and lateral vibration model are founded simultaneity. Many methods are used to build up this model, including finite element technique, numerical technique and computer simulation. The dynamic model reveals the dynamic action of string, it is instructive to design new rock bit and study drilling mechanics.     

Vibration characteristics of face-gear transmission system with parametric excitation

In order to study the influences of different factors on nonlinear dynamics of face-gear transmission system, a nonlinear dynamic model is presented. This model includes backlash, general transmission error, time-varying meshing stiffness, meshing damping, bearings and external load, etc. Based on numerical analysis theory of nonlinear dynamics, the equations are solved and the bifurcation characteristics with different parameters are obtained. And the calculation results show that increasing the backlash and time-varying meshing stiffness will augment the dynamic load of system, but increasing the mesh damping will reduce the dynamic load effectively.     

An Unsteady Flow Analysis in Gas Transmission Pipeline Based on Theory of Functional Analysis

Branch -like pipeline is a common structure in gas transmission pipeline. In the light of the constituent properties of natural gas branch - like pipeline system, the system can be divided into fundamental constituent units. This paper presents a realistic unsteady flow model consisting of simple models of pipeline units and connecting conditions, boundary conditions and initial condition associated with units by using system analysis method. The solutions in wide sense are obtained by theory of functional analysis and operator series method, Such a method has the properties of both analytical solution and numerical solution methods. When the divided pipeline unit is larger, an intuitive approximate analytical solution may be obtained; while the one is smaller, a more accurate numerical solution may be acquired. Based on this, a general computer program has been developed for this model and solutions have been used successfully in a local natural gas transmission network in Sichuan. It is proved that the model and algorithm proposed in this paper are of the advantages of convenient calculation, high precision, time saving and wide application range by way of analysis and application.     

海上大风延伸期预报研究进展

海上大风是海洋产业的重大灾害性天气,而延伸期预报是世界性难题。目前,延伸期预报主要分成动力延伸、低频振荡、经验波传播、数理统计、气候扰动分解和集合预报等6种方法,以动力延伸中的数值模式和低频振荡中的MJO监测诊断最为流行。随着大数据时代的到来,基于大数据分析,以数值预报产品为基础的集合预报成为未来业务发展的重点方向。这6种方法都可以用于海上大风等重大灾害性天气预报,许多学者尝试较多的是气候扰动分解、低频振荡中的低频天气图等方法中的溯源技术,通过找到源头,实现重大灾害性天气的延伸期预报。     

Numerical Simulation for Dynamic Response of Large Space Cylindrical Reticulated Shell under Internal Explosion by Ritz POD Method

A numerical simulation test of the internal explosive loading on large space structure was carried out by employing algorithm ANSYS/LS DYNA.An appropriate model was established for calculating the dynamic responses of the large space cylindrical reticulated shell under inner blast loading based on the proof of correctness and reliability of the model and parameters selection.Combining the Ritz vibration mode superposition method with the Proper Orthogonal Decomposition (POD) method, the problems of spatiotemporal asynchrony of shock waveforms and pressure distributions on large space structure surface were solved and the calculation for dynamic response of large space structure was reduced and simplified.Furthermore, the numerical simulation of dynamic responses was carried out.And the influence of the ratio of rise to span and the explosive position on the dynamic responses of the structure was studied.It was found that the calculation model was suitable for the dynamic response analysis of the large space cylindrical reticulated shell under internal explosion and the cylindrical reticulated shells with bigger ratios of rise to span were stronger in the capacity of anti explosion.In general, the damages to the large space structure caused by eccentric blast shock waves were more serious than that caused by central explosion.And it was the most disadvantageous to the edge components of the structure.The more attention should be paid to the anti explosion capacity of the support areas and the edge components while designing the shells.     

Analysis on starting characteristic of continuously variable transmission system with reflux power

Considering on the characteristics of the transmission system and some key units of continuously variable transmission system with reflux power, a dynamic simulation model and a control strategy are established. The design method of the new continuously variable transmission system is verified by simulation. The simulation result on this continuously variable transmission system shows that the rotating speed of the driven plate can rise up rapidly during starting clutch engagement, and the sliding friction power is lower than 3 kJ which is nearly equal to one third of the friction power of the traditional vehicle.     

Analysis on the stability of traffic flow with the information of two preceding cars

The stability analysis is one of the important problems in the traffic flow theory, where the congestion phenomena can be regarded as the instability and the phase transition of a dynamical system. An extended optimal velocity model is deduced by considering the effect of the information of two leader cars. The stability condition of the extended model is obtained by using the linear stability theory. The modified Korteweg-de Vries (mKdV) equation is derived to describe the traffic behavior near the critical point by applying the nonlinear analysis. The numerical simulation results demonstrate the analytical results and show that the traffic congests are suppressed more efficiently by considering two vehicles ahead. Therefore, the next-nearest-neighbor car has strong effects on traffic dynamics and plays an important role on stabilizing the traffic flow.     

ANALYSIS OF THE DYNAMIC STABILITY OF DUALEXCITED SYNCHRONOUS GENERATORS WITH NON-DAMPING WINDINGS

This paper analyses in detail the dynamic stability of thedual-excited synchronous generators with non-damping windings,and sets up theundamental equations and the linearized mathematical model for small distur- bance analysis.By an example with computer results,the paper also compareshe difference of the dynamic stabilities between the single-and dual-excited synchronous machines,which explains that the dual-excited synchronous gene- rators can increase the dynamic stability of machines under certain conditions.     

Selection of four hoisting points for large span steel trusses based on strain energy method

The strain energy method is applied to hoisting point selection in structural hoisting, and the feasibility of this method is investigated. Based on the number of hoisting points, a structural analysis is carried out for each possible combination of hoisting points in the whole variable space of nodes. The strain energy corresponding to the each combination is obtained based on the member forces from the structural analysis. The combinations are sorted based on their magnitudes of strain energy, and the combination with the smallest strain energy is picked out. The structure needed to be hoisted is in a rational state when it has low strain energy. The combination with the smallest strain energy is treated as the best selection of hoisting points. Hoisting construction of a workshop in Chongqing was taken as an example and three construction conditions were considered. The commercial package ANSYS was used to conduct the structural analysis and obtain the strain energy. The best selections were verified by another software MADIS.     

Computation Method and for Thermal Transmittance of Glass Curtain walls Appllcation

The heat conduction characteristic of glass curtain wall was investigated. Based on one dimensional steady heat conduction theory, the numerical calculation model of glass system thermal transmittance was set up by using insulating glass as an example. Based on two dimensional steady heat conduction theory and finite element method, both the thermal transfer matrix and temperature load array of 3 DOFs triangular element were derived. Then the revised formulas about the heat transfer matrix and temperature load array under the boundary conditions of constant heat flux, heat convective, radiation and coupled of them were also derived. Then the numerical calculation models of glass curtain wall frame and linear thermal transmittance were set up. The program TJCW based on the Visual C++ and ObjectARX was developed for calculating the thermal transmittance of glass curtain wall and was validated by contrast with the results calculated by thermal software LBNL. Finally, TJCW program was used to calculate and check the thermal transmittance of glass curtain wall in a practical project. The results indicate that the thermal transmittance of glass curtain wall can be calculated correctly by adopting the presented model, and the program based on this model can be used in energy conservation calculation and analysis in the actual projects.     

青海气候模式解释预报产品的开发及其检验

基于1982—2016 年的气候模式数值预测产品资料,整理分析生成未来45 天北半球500 hPa 高度场和本地气温、降水资料,应用降尺度方法和PP、MOS预报工具建立了预报模型及其业务系统平台。结果表明：业务系统平台构建必须考虑系统结构和功能的先进性、数据存储传输备份的经济性、系统管理的可维护性;此外,还要兼顾前瞻性、开放性、稳定性、安全性和拓展性。系统模块编制采用前端网页、后端程序、模型—视图—控制器的模式和通用的通信协议技术。适合青海高原气候模式解释应用的降尺度方法是车氏多项式、EOF经验正交函数分解和预报量的分区。2012—2016 年青海35 个样本的月降水量、51 个样本的月平均气温预报建模试验的平均评分分别为64%和75%,预报试验获得较高评分的关键是选择最好的因子构建方案和制作预报的回归预报方法。     

Dynamic analysis of high speed motorized spindles with eccentrics

In order to study dynamic behaviors of high speed motorized spindles under different eccentric conditions,the dynamics of high speed motorized spindles is analyzed by using finite element method on the basis of its structure,and an analytical dynamic model of high speed motorized spindles is established. Based on electromagnetism and mechanical system dynamics,expressions of general unbalanced force of high speed motorized spindles are established. Thus,dynamic characteristics of spindles,such as natural frequencies and unbalance response,can be obtained from the proposed model while spindles have different preloads and bearing configurations. The parameters of a 120MD60Y6 motorized spindle are substituted into the model and a simulation is carried out by Matlab/Simulink. The result shows good agreement with the data obtained from experimental modal analysis,which proves that the proposed model is correct.     

Unbalance response analysis of high speed aerostatic motorized spindle rotor system

According to the high speed of aerostatic motorized spindle, the complex dynamic behavior and the unbalance incentive, dynamical model is built up on the basis of Lagrange equation. And it is includes the differential equatioan of free vibration and forced vibration.Then, the residual unbalanced inertial centrifugal force and the mechanism of unbalanced magnetic pull are analyzed. Finally, a motorized spindle rotor-gas bearings system with the highest working speed of 250 000 r/min is simulated in the way of the unbalance excitation harmonic analysis. The dynamic behavior of high-speed aerostatic motorized spindle is revealed in supercritical mode at unbalance excitation.A theoretical basis is provided for the optimization design, vibration control to the rotor system of high-speed aerostatic motorized spindle in engineering application.     

Numerical method for galloping of icing twin bundle conductors

The dynamic balance equation of the system is set up by means of the Hamilton variational principles with the constraint conditions of the clamp points of spacers in the sub conductors by the penalty function. The numerical simulation for galloping of twin bundle conductors is achieved with the time integral by Newmark method and the Newton Raphson iteration solution for nonlinear equation. The validity is approved with simulation for the galloping of horizontal and vertical icing twin bundle conductor. The difference of aerodynamic loads, which is due to the impacts of wake flow of windward sub conductor on lee sub conductor, on the individual sub conductors can be considered with the proposed approach. It is appropriate for further study in the field of bundle conductor galloping.     

Process control for block erection of towering structures by bliding

Towering structures are usually of imposing height, heavy weight and poor bending and torsional rigidities. Hence, their block erection is a technology-intensive cours. Traditional manual control can hardly meet the requirements of the overall process and guarantee its safety. The combination of computer technology with conventional hoisting techniques is applied to the block erection process of towering structures to do the process study of the hoisting system first of all, and to acquire data with instruments and devices according to the process study so as to aid the decision-making and process control of block erection, to realize automatic execution of emergency measures and to guarantee the safety in the course of hoisting.     

A MODLE OF SYSTEM DYNAMIC FOR URBAN LAND PLANNING

This thesis uses the theory and method of the system dynamics to analyze the characteristics of the urban land planning system and set up the urban land planning system dynamic model, The model could describe the influence and request of factors of the society. economy and environment to the urban planning by using the system, the quantitative and the dynamic methods. By adjusting the parameter and repeating model imitation, the model could provide the possibility of realizing the present land planning and provide the quantitative analysis method for the planning department to make or adjust the land planning, and assist the government department to make decisions.     

乡村旅游业与农村部分产业协调互动的动力机制分析-以贵州为例

本文以贵州为例,从协同论、系统论观点出发,对旅游业与农村产业的内部协调和外部关联的动力机制进行探讨,分析该系统存在的良性协调互动圈层结构的动力机制,提出稳固其良性协调互动应具备的必要条件,构建乡村旅游业与农村各产业部分协调互动的动力机制“七叶水轮机”模型,揭示了外环起到稳定内环良性协调互动的功能。随着外环境变化作用于内环的动力机制表现出显著时空差异,因而该动力模型亦是一动态模型。     

A NONLINEAR PROGRAMMING MODEL AND ITS ALGORITHM FOR TRANSMISSION NETWORK PLANNING

The problem of transmission network planning is studied thoroughly by applying the mathmatical optimal tecqhniue in this paper. A novel approach is put forward for computer aided transmission network planning, which is quite different from what is based on D.C. load flow equations. A nonlinear transmission planning model is set up by regarding A.C. load flow equations as the system model. A practical model which can be solved more easily, and an united algorithm are obtained by applying the SUMT to the nonlinear model. The results of some practical examples indicate that this method can not only make the planning results more accurate, but also provide the voltage qualities and produce planning plans autometically and seek the plans optimally and fast.     

Influence of heat storage mode of domestic hot water on the performance of ground heat exchanger in ground-source heat pump system

The vertical U-tube ground-coupled heat pump system provides cold and heat for the controlling of indoor environment. Under the air-conditioning condition, the vertical U-tube ground-coupled heat pump system with heat recovery can provide domestic hot water. The influence of supplying domestic hot water on the heat transfer performance of ground heat exchangers is different under different operating modes in summer and winter. Through a project design of ground-source heat pump system, the influence of supplying domestic hot water under heat storage mode on the heat transfer performance of ground heat exchangers in summer and winter is respectively analyzed. The dynamic performance of heat exchangers under different working conditions is analyzed, and through numerical calculation, the heat transfer performance parameters of ground heat exchangers under different operating modes are obtained. From the calculation results, the adjusting methods based on the load characteristics of this project represent.