Papers through a lot of research, on a toxic and harmful substances in the production, storage and transport accidents in the course of the leakage of the status quo as well as poisonous and harmful substances in the production, storage and transport accidents in the course of the leakage on the purpose and significance. At home and abroad poisonous gas or steam-proliferation studies summarized by domestic and foreign poisonous gas or steam leakage model for the spread of contrast, select the Gaussian model as a simulation software model, and applied analysis of the consequences of the accident.In this paper, industrial chemicals were introduced, and its harm to the human body was studied. In this paper, 2001-2006, the domestic accident statistics, that the explosion, poisoning and suffocation are frequent incidents in chemical plants demonstrated in the spread of toxic and harmful substances on the simulation of chemical safety is of far-reaching significance. And through direct leaked to the cause of the accident concluded, summing up the 10 categories often leaked and four kinds of accidents caused by various reasons.Based on the complexity of these models, the amount of computation, this combination oftechnology has been developed based on Visual Basic6.0 the spread of poison simulation software, a decrease of manual calculation. Finally, the software used in the preparation of the case, the liquid chlorine leak through the simulation, and further to liquid chlorine at different atmospheric stability, the release of the source and a high degree of proliferation of surface roughness when summing up the situation was analyzed, and concluded: For the continuous leakage , The leakage rate in certain circumstances, the greater the height of the release of the source and endanger regional smaller atmosphere more unstable, endangering regional smaller regional wind speed greater harm smaller endanger the region mainly in the release of the source The wind direction, wind direction of the harm than perpendicular to the direction of the wind against a range of more than in the same region.
Post about "Simulation"
Air pollution control is a multi-variable,multi-objective,multi-level complex systems.Need for a comprehensive,interrelated,the viewpoint of development of this system of quantitative research to identify effective governance programmes.City,developed industrialized makes distribution of a wide range of sources and complex pollution emissions.Thus results in a variety of high concentrations of air pollutants there.Especially because of City is in the Pearl River Delta between of the two mega-cities which is Guangzhou and Shenzhen.In this area,the distance is small between urban and rural areas and has inter-city interaction of pollution.The atmosphere is not only on environmental issues related to local air quality improvement but also improve the quality of the Pearl River Delta region.First of all,this article analysic atmospheric environment status and trend of Dongguan,then study the characteristics of its sources of pollution emissions.Next this article use atmospheric simulation systems to study air pollutants source in Dongguan City.Based on an analysis of results of city and local sources of air quality source of the contribution to the environment and the concentration of air pollutants contribution rate,the article analysic the main sources of pollution contribution and its characteristics in Dongguan City.Finally,this article gets the actual control measures of Dongguan City.By contrast with the measured data,we found that simulation results and measured results have the same trend line.The analog method is feasible.We have the following conclusions:（1）For SO2,NO2,PM10,local sources contribute to the main status,the local source contribution rates are 80.8%,77%and 85.8%.（2）By industry,Other industries（OTHER,including restaurants,food processing industry and other sectors）make the largest contribution to SO2; Mobile source（MOBILE）make the largest contribution to NO2;No organization emissions make the largest contribution to PM10.（3）Through the implementation of targeted control measures,Dongguan will improve the air quality,access to economic, and environmental aspects of the benefits.
For the purpose of explosion prevention in industry and development of new conception weapons, the fundamental study of multi-point dispersal explosion has been carried out in combination of experiments with simulations. In this thesis, background and status about fuel dispersal research was firstly summarized, then fuel dispersal experiments were done to study the disciplinarian of fuel dispersal explosion and cloud formation, and the formulas for describing the relationship between the expanding diameter D and the time t(D-t curves)were fitted by the experimental data. In order to analyze the influence of different factors on fuel concentration, aprogram was compiled to simulate the fuel concentration of multi-point dispersal process on the MATLAB platform by combining with the D-t curves. The experiments on multi-point dispersal explosion were done by selecting one of liquid fuels as sample to study the dispersal and cloud formation, the overpressure, impulse and temperature of shock waves with the measurement techniques, such as photography, VXI measurement system of shock wave, infrared thermal imager. was compared with a kind of explosive mixture and TNT under the same conditions. The results show that the speed of wind has significant influence on the process of fuel dispersal and cloud formation, and the concentration of multi-point dispersal process has presented a gradually decreasing tendency from center to circumference, the concentration effected mainly by dispersal rate but less by the dispersal time intervals and space distribution. can be seen from the experimental results that in the process of multi-point dispersal explosion, the overpressure produced by the liquid fuel was higher than those of the explosive mixture and TNT, the temperature and impulse were little lower than those of the explosive but higher than TNT.
J.B. Pendry has proposed a coordinate transformation approach to design invisibility cloaks in 2006. However, an ideal cylindrical cloak derived from coordinate transformation is inevitably unphysical at its inner boundary. Thereforeis meaningful to investigate practical designing methods. In this thesis work, three practical designing approaches for cylindrical cloaks are presented.Our first involves a replacement of a thin layer of material at an ideal cloak’s inner surface by a homogeneous material layer. The second method investigates a new material component curve. These two approaches effectively avoid the infinities in material parameters, and at the same time produce practical near-ideal invisibility cloaks. The cloaks obtained are perfectly matched in impedance at the outer boundary. We quantitatively show the effect of the transformation order to the proposed cloak’s scattering coefficients. In addition, the third approach suggests an electromagnetic cloak, which is simplified by layered structures of homogeneous isotropic materials. We will quantitatively examine the effect of the total number of the homogeneous isotropic layers to this type of cloak’s scattering coefficients. These three types of practical invisibility cloaks are helpful to realize a near-ideal invisibility cloak device.
Integrated production has come true in modern industrial process, and the equipments are increasingly large and complicated, which require the entire equipment even a joint enterprise to achieve optimal design, optimal control and optimal management. So evaluating the energy consumption in process and enhancing the thermodynamic performance of process are particularly important.Exergy optimization of large chemical processes can be difficult because the local efficiencies of subsystems are interdependent in a way which was heretofore difficult to anticipate. The impact of exergy efficiencies of subsystems on overall exergy efficiency of the whole system is uncertain. So’s necessary to develop a universal formula which is independent of the structure of a system and relate the total exergy efficiency of any system to the efficiencies of its subsystems. This paper studied the application of the for the thermodynamic optimization of process of manufacturing ethylene from ethanol to obtain the optimal thermodynamic structure of the process. The following points are emphasized:1. The operation models of the existing ethylene production process by ethanol dehydration were set up for the simulation, and the thermodynamic model was aslo determined.2. The existing ethylene production process by ethanol dehydration was simulated by making use of the chemical simulation software ASPEN PLUS, and the exergy analysis was carried out based on the simulation results. The obtained exergy efficiency and other parameters supplied reference to the optimization of existing process and simulation of improved processes.3. The improved processes were put forward according to . simulation of these processes were carried out by ASPEN PLUS, then exergy analysis was done.4. This paper studied the application of for the process optimization of chemical process which contains a heat exchanger network; For the chemical process system contained multi-effective distillation, the way of analysis with exergy load distribution method was also studied. 5. On the basis of total exergy efficiency of whole system, the simulation results of existing process and improved cases 1 and 2 showed that the case 1 was better. The way to analyze multi-effective distillation can affect the distribution of exergy load observably; The heat exchanger network was treated as a single operation, which greatly simplified the graphical representation of the exergy analysis and necessary computations.
At present, railway transportation is the main mode of passenger traveling in our country, as the interface place of railway and passenger, research on its passengeris of great significance.As an effective approach of management, early-warning which was widely used in various field has achieved remarkable results. According to the actual situation, a passenger safety early-warning management system of railway passenger station was established in this paper which based on general safety warning based on the theory of management. The main study as follows:(1) Researching and summing up the main types of safety issues in railway passenger station , a detailed analysis of the main reason was made, and mastering the characteristics on time and space of this safety issues.(2) Early warning passenger safety management system was established, and the system’s organizational structure and functions of distribution was improved . In accordance with system needs appropriate equipment was equipped and developing the pre-control measures.(3) Based on the analysis for the main types and characteristics of the current indicators, a complete integrity of the passenger station was built . Improved method was used in evaluating the safety status of passenger station, and developing the principle for locating the source of system risk to achieve the identification and diagnosis process and start the related pre-control measures.(4) Practicability and efficiency of the Improved method was proved by simulation in Matlab software.
Crude oil contains a lot of fine sand which has impact on the gathering and transportation system seriously. The equipments used for desanding are settlement pool,s and . However, lacks of them were also exposed, so the development of more appropriate separation equipment is necessary.This paper designs impeller dynamic s and the performance testing systems of hydrocyclones. does systematic experimental tests and theoretical analyses to hydrocyclones. In the experiment, tests and analyses the impact of motor speed, split ratio, feed flux and other parameters on pressure loss and separation efficiency of three dynamic hydro cyclones. The result shows that the higher the motor speed, the bigger the centrifugal strength, the better the separation effect, but the overflow pressure drop is on the increase at the same time. Higher split ratio can effectively improve the separation efficiency with less impact on pressure drop. The increase of feed flux has less effect on the separation efficiency, but the pressure drop of overflow and underflow are increasing. Through orthogonal analysis, the primary effect factor on separation efficiency is motor speed, followed by the split ratio and feed flux. The primary influential factor on pressure drop is motor speed, followed by the feed flux and split ratio. Compared with ordinary hydrocyclone, impeller dynamic hydrocyclone has higher separation efficiency, bigger feed flux range and smaller pressure drop.Based on the experimental results, it can be obtained that the flat-vane cylinder dynamic hydrocyclone have the highest separation efficiency, followed by the vortex-board cylinder dynamic hydrocyclone and flat-vane cone dynamic hydrocyclone. Compared with the results of experimental prototype loss of pressure, flat-vane cone dynamic hydrocyclone have the smallest pressure drop, followed by he vortex-board cylinder dynamic hydrocyclone and the flat-vane cylinder dynamic hydrocyclone.Having simplified the three sort of experimental prototype models and established N-S equations and continuous equation, I get the information of the inner flow. It is shown by the simulation results that the flow in the impeller dynamic hydrocyclone has a high tangential velocity about 14～15m/s, and the centrifugal force is 5～10 times bigger than the ordinary hydrocyclone. Compared with the experimental data and the simulation results, it can be proved that the mathematic model is appropriate for this problem. Based on the analysis of the three sort of experimental prototype models’ comprehensive properties and utilizing the mathematic model established, the improvement scheme of dynamic hydrocyclone has been given.To analyze the reason of overflow pressure drop obtain that the force vortex is the primary reason of overflow pressure drop. It can be controlled by enlarging the diameter of vortex finder or setting the diffuser in order to weaken and eliminate the force vortex.The impeller dynamic hydrocyclone has a bigger centrifugal force, higher separation efficiency, smaller pressure drop and on clogging. Therefore it must have good prospects and the high value of commercial application.
Energy-absorbing, thin-walled, impact-resistant metal structures have been widely used in aircrafts, automobiles, trains and ships and other transportation apparatus as the parts ofof impact kinetic energy. Therefore, extensive attentions have been drawn on performance investigations of energy absorption of various forms of thin-walled metal structures.This thesis is funded by The National Science Foundation of China (Projects 10332010, 10721062) and The National Research Program of China (Project 2006CB601205).The light-weight, thin-walled metal structures are studied in this paper. A new type of energy -absorbing structure is proposed to investigate the structural deformation mechanism and energy absorption under transient axially compressive impact loadings.The research work can be summarized as follows:(1) System description and analysis of theoretical models of cylindrical metal shell under axial compressive loadings, and numerical simulations for three thin-walled metal structures possessing the same cross-sectional areas loaded by transient axial pressures. The patterns of deformation and performances of energy absorption are compared and analyzed, respectively.(2) Numerical simulation for complicated energy absorption of a truss- reinforced sandwich-type cylinder tube with large displacement and large strain. The numerical model is established based on the nonlinear finite element theory. The property of energy absorption under axial impact loadings is investigated with the proposed model. Various impact speeds and internal truss layouts are used to study how they affect the capability of energy absorption of the compound tube. The numerical results present a valuable reference to design light weight composite structures with the best performance of energy absorption under impact circumstance.(3) Numerical modeling of a cylinder tube with a finite length of crack is presented based on the fracture mechanics theory with an appropriate criterion for fracture. The deformation and damage are predicted and numerically analyzed considering nonlinear transient axial compressive loadings.
The Finite Element Modeling and Numerical Simulation of Centerless Cylindrical Grinding Characteristic
As a precision machining technique which can get high precision and low roughness, cylindrical centerless-type grinding has an important position in the field ofmanufacturing. The dynamic and thermal characteristic in centerless grinding systems will affect the machining precision of the workpiece largely, so is very pivotal to study the dynamic and thermal characteristic of mechanisms thoroughly to improve machining performances. The thesis belongs to the project of” of roundness forming in the centreless grinding machine by Wuxi Koyo Industry Co.,Ltd.”Combined with the development of grinding technology at home and abroad, some researches as followed are studied.Firstly, from the research of the cutting with a simplified single abrasive particle, the theoretical model of the normal grinding force and the tangential force during cylindrical plunge grinding in three phases are proposed. is completed with Matlab6.5, and the simulation curves of the grinding force are performed. According to the experimental results, the empirical constant q is corrected in order to gain the consistent simulation results, which indicates that the theoretic model proposed in the paper is reasonable and feasible. Based on the analysis foundation, the dynamic analysis and simulation results of the total cylindrical centerless-type grinding system during the workpiece in steady movement, which will make for the force load in the ANSYS.The model of grinding machine housing is carried out with Pro/E, and the finite element model is constructed. After the thermal load and boundary conditions are defined, the steady-state temperature and transient temperature distribution are obtained. By using indirect thermal-structure coupling method, heat distortion of the grinding machine housing is finished. The results indicate that the distortion of spindle system is reduced gradually from left to right, and the max distortion occurs at the front of the above coping, which will help the workpiece improve the machine precision.The model of regulating machine housing and blade are constructed with Pro/E and ANSYS. Through the transient dynamic analysis, gets the equivalent displacement field, strain field, stress field distribution contour map of the system and their distortions drawing during the grinding process. The thesis proposes some suggestions about reducing distortions of the blade according to the distortion principle. Finally, the distortion of the regulating machine housing which will affect the machining precision is relatively smaller after compared.
With people’s life becoming better and better, the tourism has been becoming more and more popular, which develops the passengers transportation by sea. Since the development of water shipping, serious fire disaster on passenger liner occurred frequently, which cause serious casualties and wealth damage. Characteristics of the passenger liner, such as the comparative closeness, limitation of escaping routes, and long time consumption for escape, hinder the passenger evacuation in emergency seriously.Firstly, this paper analyses factors affecting the safe evacuation, including objective factors and subjective factors. In the objective factors part, the major factors affecting the evacuating time are analyzed; while in the subjective factors part, the inadaptability factors, such as theories about panic, about emergency degree, and about decision making, are introduced, in which people’s response in emergency is specially analyzed. Secondly, the simulation model of mass movement is briefly introduced, through which, the process of mass movement is displayed. The model of safe evacuation cumulative time is made through major factors and parameters analysis in safe evacuation model. According to characteristics of onboard people evacuation in fire, choking phenomenon during the process of safe evacuation on passenger liner is studied, and the evacuation on passenger liner is analyzed. By employing mathematical model, mechanism of choking in evacuation is analyzed, and the related factors and controlling methods are studied, which leads to suggestions for safe evacuation in passenger liner.