工程常见输元的特性准则及其计算

输元是组成灯用传递模型的基本单元。提出三类9项输元特性准则。研究确定传热传递、能量转换传递、传质传递三大类8种典型输元的特性准则,并给出了相应的计算式或表达式,为规范建立基本工程传递模型、简化复杂系统的工程传递分析提供了基础。

Influence range of emergency under special events based on CTM

To determine the dynamic influence range of emergencies under special events, the spacial and temporal characteristics of the traffic flow are studied by simulation based on the cell transmission model （CTM）. Based on the traffic management measures used under special events, a semi-dynamic assignment algorithm is proposed, which is combined with an algorithm for logit multi-path traffic assignment and the CTM. In a simple calculation network, the spacial and temporal characteristics of traffic flows which vary with different traffic management schemes are studied, and a method to obtain the influence range of emergency is proposed by computing the jam time of the intersections. By contrasting the average delay of each vehicle, the dissipation effect is studied under two different traffic management schemes. The example shows that the spatial and temporal variety of the traffic flow can be easily simulated and the influence range of emergency can be confirmed by the method based on the CTM. The proposed method provides a new idea for decision-making on traffic management under emergency under special events.

Optimization method for evacuation zone with network reconfiguration based on dynamic simulation

Abstract： With a determinate danger zone and evacuation demand caused by an emergency, an optimization method for the evacuation zone with network reconfiguration based on dynamic simulation is proposed. The method contains three modules. First, the network in the evacuation zone is optimized by a model with the integrated strategy of lane reversal and intersection conflict elimination. Secondly, the dynamic evacuation simulation model based on the cell transmission model is applied to simulate the dynamic propagation process of evacuated vehicles in the network in the evacuation zone. The evacuation time for all evacuated vehicles leaving the danger zone is obtained and the setting of the current evacuation zone is fed back. Thirdly, the arrival distributions of evacuated vehicles at critical intersections of the evacuation zone are also obtained to estimate the delay at critical intersection to determine whether the intersection should be taken as the critical intersection in the next iteration. The evacuation zone is expanded gradually through iteration, and the reasonable evacuation zone and the optimal evacuation network is confirmed. Based on the survey of the parking lot and urban street network around Nanjing Olympic Sports Center, the models and the iterative algorithm were applied to obtain the optimal plan of the evacuation zone with network reconfiguration in an evacuation situation to verify the validity of the proposed method.

FEM modeling of softened base metal in narrow-gap joint by CMT+P MIX welding procedure

A required finite element method（FEM） model applicable for narrow gap CMT and CMT＋P MIX welding was established based on the interactions between arc,base metal and filler metal.A novel method of simplifying wire feeding pulses and heat input pulses was supposed under the conduction of equivalent input.The method together with composed double-ellipse heat sources was included in the model.The model was employed in the investigation of thermal cycling and the identification of the softened zone of AA7A52 base plates.Low-frequency behavior emerged in the form of low-cooling rate sects,which were not expected under experimental conditions.The softened zone including the quenched zone and averaging zone of the base plate was much wider internal the base plate than that close to the surfaces.The reliability of the predictions in thermal cycling was supported by infrared imaging test results of the thermal cycle process.

A Novel Charge-Transfer Matching Cell for High-Precision Correlation and Low-Power

A novel matching cell circuitry using charge transfer circuit technique for high precision correlation calculation is presented.The cell calculates the absolute value of the difference between two analog input voltages and amplifies the result.Amplification gain can be designed by the capacitance size in the cell and threshold voltage mismatch can be canceled automatically,thus high precision operation of the circuit is achieved.The circuit can be operated with low power dissipation of about 12μW at a frequency of 50MHz.Because of its simple structure and small silicon area,the matching cell is suitable to realize the correlation dealing with many template vectors that have many elements in a chip.

Mechanical analysis of transmission lines based on linear sliding cable element

In order to study the sliding characteristics when the cable structures are connected with other rods, a string of sliding cable dements （SCE） consisting of one active threenode SCE passing through the sliding point and multiple inactive two-node SCEs is put forward. Based on the updated Lagrangian formulation, the geometric nonlinear stiffness matrix of the three-node straight sliding cable dement is deduced. The examples about two-span and three-span continuous cable structures are studied to verify the effectiveness of the derived SCE. Comparing the cable tension of SCE with the existing research results, the calculating results show that the error is less than 1%. The sliding characteristics should be considered in practical engineering because of the obvious difference between the cable tension of the SCE and that of the cable element without considering sliding characteristics.

A Single Neuron with Stochastic Resonance for Noisy Square Pulse Train Signal Transmission

A nonlinear single neuron is demonstrated to exhibit stochastic resonance by theoretical analysis and numerical simulations. This single neuron is used for noisy periodic signal transmission, and significant performance of raising input output SNR gain can be achieved. The research of this paper not only gives a very simple model of neuron with stochastic resonance, but also enlarges the application scope of neuron to the transmission of periodic signals.

Graph Clustering Algorithm for RT Level ALU Technology Mapping

Register transfer level mapping (RTLM) algorithm for technology mapping at RT level is presented,which supports current design methodologies using high level design and design reuse.The mapping rules implement a source ALU using target ALU.The source ALUs and the target ALUs are all represented by the general ALUs and the mapping rules are applied in the algorithm.The mapping rules are described in a table fashion.The graph clustering algorithm is a branch and bound algorithm based on the graph formulation of the mapping algorithm.The mapping algorithm suits well mapping of regularly structured data path.Comparisons are made between the experimental results generated by 1 greedy algorithm and graphclustering algorithm,showing the feasibility of presented algorithm.

Requirements for transfusion and postoperative outcomes in orthotopic liver transplantation:A meta-analysis on aprotinin

AIM:To study the effect of aprotinin used in orthotopic liver transplantation (OLT) on the intraoperative requirement for blood products and on the incidence of laparotomy for bleeding, thrombotic events and mortality. METHODS: A systematic review of the literature in the electronic database Medline and the Clinic Trials Registry Database was performed. Literature that did not fit our study were excluded. Patients in the reviewed studies were divided into two groups; one group used aprotinin (aprotinin group) while the other did not (control group). The data in the literature that fit our requirements were recorded. Weighted mean differences (WMD) in the requirements for blood products between the aprotinin group and the control group were tested using a fixed effect model. A Z test was performed to examine their reliability; the Fleiss method of fixed effect model was used to analyze data on postoperative events, and odds ratios (ORs) were tested and merged. RESULTS: Seven citations were examined in our study. Among them, a requirement for blood products was reported in 4 studies including 321 patients, while postoperative events were reported in 5 studies including 477 patients. The requirement for red blood cells and fresh frozen plasma in the aprotinin group was statistically lower than that in the control group (WMD=-1.80 units, 95% CI,-3.38 to-0.22; WMD=-3.99 units, 95% CI,-6.47 to-1.50, respectively). However, no significant difference was indicated in the incidence of laparotomy for bleeding, thrombotic events and mortality between the two groups. Analysis on blood loss, anaphylactic reactions and renal function was not performed in this study due to a lack of sufficient information.CONCLUSION: Aprotinin can reduce the intraoperative requirement for blood products in OLT, and has no significant effect on the incidence of laparotomy for bleeding, thrombotic events and mortality.

Finite element simulation of food transport through the esophageal body

The peristaltic transport of swallowed material in the esophagus is a neuro-muscular function involving the nerve control, bolus-structure interaction, and structure-mechanics relationship of the tissue. In this study, a finite element model (FEM) was developed to simulate food transport through the esophagus. The FEM consists of three components, i.e., tissue, food bolus and peristaltic wave, as well as the interactions between them. The transport process was simulated as three stages, i.e., the filling of fluid, contraction of circular muscle and traveling of peristaltic wave. It was found that the maximal passive intraluminal pressure due to bolus expansion was in the range of 0.8-10 kPa and it increased with bolus volume and fluid viscosity. It was found that the highest normal and shear stresses were at the inner surface of muscle layer. In addition, the peak pressure required for the fluid flow was predicted to be 1-15 kPa at the bolus tail. The diseases of systemic sclerosis or osteogenesis imperfecta, with the remodeled microstructures and mechanical properties, might induce the malfunction of esophageal transport. In conclusion, the current simulation was demonstrated to be able to capture the main characteristics in the intraluminal pressure and bolus geometry as measured experimentally. Therefore, the finite element model established in this study could be used to further explore the mechanism of esophageal transport in various clinical applications.

Impacts of flexible obstructive working environment on dynamic performances of inspection robot for power transmission line

The rigid-flexible coupling dynamic modeling and simulation of an inspection robot were conducted to study the influences of the flexible obstructive working environment i.e. overhead transmission line on the robot＇s dynamic performance. First, considering the structure of the obstacles and symmetrical mechanism of the robot prototype, four basic subactions were abstracted to fulfill full-path kinematic tasks. Then, a multi-rigid-body dynamic model of the robot was built with Lagrange equation, whil^e a multi-flexible-body dynamic model of a span of lin~ was obtained by combining finite element method （FEM）, modal synthesis method and Lagrange equation. The two subsystem models were coupled under rolling along no-obstacle segment and overcoming obstacle poses, and these simulations of three subactions along different spans of line were performed in ADMAS. The simulation results, including the coupling vibration parameters and driving moment of joint motors, show the dynamic performances of the robot along ftexibile obstructive working path： in flexible obstructive working environment, the robot can fulfill the preset motion goals; it responses slower in more flexible path; the fluctuation of robot as well as driving moment of the corresponding joint in startup and brake region is greater than that in rigid environment; the fluctuation amplitude increases with increasing working environment flexibility.

Simultaneous effects of joint spacing and joint orientation on the penetration rate of a single disc cutter

This paper describes the influence of joint spacing and joint orientation on the penetration rate of a Tunnel Boring Machine （TBM） disc cutter as modeled by the Discrete Element Method （DEM）. The input data for the siLmulations were obtained from the sandstone along the AIborz tunnel that is currently being excavated in Iran using a 5.2 m diameter open TBM. Three joint spacings, 150, 200, and 300 mm, were modeled together with seven values of joint orientation; 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The results show that the penetration increases when joint orientation increases from 0° to 75°, but it decreases as the joint orientation increases further from 75° to 90°. This is true for each joint spacing. In addition, for a given joint orientation increasing the joint spacing causes the TBM penetration to decrease. The optimum joint orientation, from the viewpoint of TBM penetration, is about 60-75°.

FEM Simulation on Artificial Freezing of Seepage Ground

The coupling mechanism in freezing process of seepage ground was studied and a simplified coupling math model was proposed. The nonlinear and coupling problems of PDEs were well solved using the exponential function, error function and normal distribution function, and a series of FEM equations of coupled fields of temperature and seepage were deduced and put forward. With the example of shaft ground freezing, the formation of freezing wall in seepage ground was simulated.

Study on Dynamic Response of the “Dualistic” Structure Rock Slope with Seismic Wave Theory

Currently, scant attention has been paid to the theoretical analysis on dynamic response mechanism of the ＂Dualistic＂ structure roek slope. The analysis presented here provides insight into the dynamic response of the ＂Dualistie＂ structure rock slope. By investigating the principle of energy distribution, it is shown that the effect of a joint plays a significant role in slope stability analysis. A dynamic reflection and transmission model （RTM） for the ＂Dualistic＂ structure rock slope and explicit dynamic equations are established to analyze the dynamic response of a slope, based on the theory of elastic mechanics and the principle of seismic wave propagation. The theoretical simulation solutions show that the dynamic response of the ＂Dualistic＂ structure rock slope （soft-hard） model is greater than that of the ＂Dualistic＂ strueture rock slope （hard-soft） model, especially in the slope crest. The magnifying effect of rigid foundation on the dynamic response is more obvious than that of soft foundation. With the amplitude increasing, the cracks could be found in the right slope （soft-hard） crest. The crest failure is firstly observed in the right slope （soft-hard） during the experimental process. The reliability of theoretical model is also investigated by experiment analysis. The conclusions derived in this paper could also be used in future evaluations of Multi-layer rock slopes.

Modeling Electron Transport in Vertical-SOI NMOSFET by Directly Solving BTE with FEA

A numerical schemes applicable to the direct solution of Boltzmann transport equation (BTE) in vertical-SOI NMOSFET are investigated by means of the finite element analysis (FEA).The solution gives the electron distribution function,electrostatic potential,carriers concentration,drift velocity,average energy and drain current by directly solving the BTE and the Poisson equation self-consistency.The result shows that the direct numerical solution of the BTE with the aid of FEA and vertical SOI NMOSFET is a promising approach for ultra short channel transistors modeling.

Transmission Line Sequence Impedances Identification Using PMU Measurements

An online TL （transmission line） impedance TPIS （transmission line parameter identification system） using PMU （phasor measurement unit） was recently developed and implemented at CSG （china southern power grid company）, Traditional approaches for TL impedance calculation only approximate the effect of conductor sags and ignore the dependence of impedances on temperature variation. Utilizing PMU measurements may improve the accuracy of TL parameters calculation. The challenge is that the parameters identified are very sensitive to noise and errors in PMU measurements, which are difficult to quantify and can be uncertain under different system operating/loading condition, TPIS provides an innovative yet practical problem formulation for TL sequence parameter estimation based on least-squares with linear constraints. A bootstrapping-based resampling technique is developed and a new metric is proposed to determine the credibility of the estimated sequence impedances. This paper discusses the proposed methodologies, challenges, as well as implementation issues identified during the development of TPIS.

Unitary Transformation in Quantum Teleportation

In the well-known treatment of quantum teleportation, the receiver should convert the state of his EPR particle into the replica of the unknown quantum state by one of four possible unitary transformations. However, the importance of these unitary transformations must be emphasized. We will show in this paper that the receiver cannot transform the state of his particle into an exact replica of the unknown state which the sender wants to transfer if he has not a proper implementation of these unitary transformations. In the procedure of converting state, the inevitable coupling between EPR particle and environment which is needed by the implementation of unitary transformations will reduce the accuracy of the replica.

Determination of Transport Properties of Dilute Binary Mixtures Containing Carbon Dioxide through Isotropic Pair Potential Energies

The present work is concerned with extracting information about intermolecular potential energies of binary mixtures of CO2 with C2H6, C3H8, n-C4Hlo and iso-C4Hlo, by the usage of the inversion method, and then predicting the dilute gas transport properties of the mixtures. Using the inverted pair potential energies, the Chap- man-Enskog version of the kinetic theory was applied to calculate transport properties, except thermal conductivity of mixtures. The calculation of thermal conductivity through the methods of Schreiber et al. and Uribe et al. was discussed. Calculations were performed over a wide temperature range and equimolar composition. Rather accurate correlations for the viscosity coefficients of the mixtures in the temperature range were reproduced from the pre- sent unlike intermolecular potential energies. Our estimated accuracies for the viscosity are within ±2%. Acceptable agreement between the predicted values of the viscosity and thermal conductivity with the literature values demon- strates the predictive power of the inversion scheme. In the case of thermal conductivity our results are in favor of the preference of Uribe et al.＇s method over Schreiber et al.＇s scheme.

Computer simulation of flow and mixing at the duodenal stump after gastric resection

AIM： To investigate the flow and mixing at the duodenal stump after gastric resection, a computer simulation was implemented. METHODS： Using the finite element method, two different Billroth fl procedure cases （A and B） were modeled. Case A was defined with a shorter and almost straight duodenal section, while case B has a much longer and curved duodenal section. Velocity, pressure and food concentration distribution were determined and the numerical results were compared with experimental observations. RESULTS： The pressure distribution obtained by numerical simulation was in the range of the recorded experimental results. Case A had a more favorable pressure distribution in comparison with case B. However, case B had better performance in terms of food transport because of more continual food distribution, as well as better emptying of the duodena section. CONCLUSION： This study offers insight into the transport process within the duodenal stump section after surgical intervention, which can be useful for future patient-specific predictions of a surgical outcome.

Influence of wave and current on deep-sea mining transporting system

As a solution to the breaking of pipeline under high axial force,carbon fiber composite pipe with low density and high intensity is applied to deep-sea mining transporting system.Based on the fact that the transporting pipe is under the forces of gravity,inner liquid,buoyancy as well as hydrodynamic force,geometric nonlinear finite element theory has been applied to analyzing the transporting system.Conclusions can be drawn as follows.Under the interaction of waves and currents,node forces FX and FZ acted by the transporting pipe on the mining vehicle are less than 2 kN,which indicates that waves and currents have little influence on the spatial shape of the transporting pipe and the mining vehicle movement.On the other hand,the horizontal force acting on the mining ship could be as large as 106 830 N,which has great influence on the mining system.