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Virtual Mold Technique in Thermal Stress Analysis during Casting Process
It is important to analyse the casting product and the mold at the same time considering thermal contraction of the casting and thermal expansion of the mold. The analysis considering contact of the casting and the mold induces the precise prediction of stress distribution and the defect such as hot tearing. But it is difficult to generate FEM mesh for the interface of the casting and the mold. Moreover the mesh for the mold domain spends lots of computational time and memory for the analysis due to a number of meshes. Consequently we proposed the virtual mold technique which only uses mesh of the casting part for thermal stress analysis in casting process. The spring bar element in virtual mold technique is used to consider the contact of the casting and the mold. In general, a volume of the mold is much bigger than that of casting part, so the proposed technique decreases the number of mesh and saves the computational memory and time greatly. In this study, the proposed technique was verified by the comparison with the traditional contact technique on a specimen. And the proposed technique gave satisfactory results....
2020-11-22 17:58:37浏览：60
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Modeling of polishing process for electric stainless- steel kettle
The market of stainless electric steel kettles is growing significantly,but the main mechanism for polishing kettles via traditional handwork operations limits the growth of electric kettle manufacturing.Based on the successful multi-tool automatic polishing system for electric stainless steel kettles,regression analysis and orthogonal tests were employed to construct a polishing process model,with a purpose to improve the automatic polishing technology for electric stainless steel kettles.The model reveals the relationship between the surface roughness and processing parameters including gringding depth,abrasive tangent speed,workpiece rotating speed and axial feeding speed.Simulation and experimental results are in agreement,which shows that this modeling method is feasible in practice,and it can also be used as a guidance for planning automatic polishing process of electric stainless-steel kettles....
2020-11-11 22:33:38浏览：77
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A method to simulate multilayer welding process: Node dynamic relaxation method
A new method called node dynamic relaxation is proposed to simulate multilayer welding. A two dimensional plane strain model for multilayer welding is simulated and the results show that mesh distortion can be decreased, and it is also found that the node dynamic relaxation is a kind of method to calculate welding deformation accurately by comparing experiment results with simulation results....
2020-11-11 22:33:38浏览：69
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Filling analysis for thixomolded process of AZ91D magnesium alloy
Mold filling in lately-developed Thixomolding(R) process is a complex process, of which numerical simulation is necessary for development. Governing equations and numerical models are first given, and then the experiment and its filling simulation are carried out. The results demonstrate that the modeling temperature changes from 864 to 873 K when the barrel temperature is 873 K. The difference is primarily in the runner system, but nearly invariable in the part. Consequently, the slurry fills the cavity smoothly with low solid fraction, and the filling process finishes in 5 ms, the filling process completes successfully before solidification of the slurry, which has good agreement with the experiment. Through a snapshot of the filling process and defects tracking, drawbacks are displayed and confirmed in the experiment....
2020-11-11 22:33:38浏览：60
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A Brief Analysis to the 3-Step Translation Process
With the development of science and technology,the culture of translation still is multiplied continuously.However.how can you translate a good target text quickly and accurately?We should master transhtion skills and seep basic steps in translating.As the matter of fact,translation is expressed language actives through using a language to another language exchanged with the accuracy and integrity of thinking.Some call it an art,and yet some others take it as a career.but no matter what the purpose is,the process oftranslation has its certain steps.A translator will have to understand the source text fust.and then conduct her/his translation and then,proofread the source text.In addition,translation standard,which is Faithfulness,Expressiveness,Elegance,phy an important role in the translation process.A brief analysis of the problems mentioned above is made....
2020-11-11 22:33:38浏览：73
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Chaos analysis of acoustic emission signals in spot welding process
Bused on chaos time series and fiactal theory, acoustic emission signals were studied in the process of spot welding. According to calculating 8 welding parameters using phase space reconstruction method, the largest Lyapunov exponents were positive values and chaos characteristics were firstly discovered from acoustic emission signals in spot welding. In order to evaluate acoustic emission signal, Hausdorff dimension is put forward to analyze and estimate chaos characteristics. The experiment and calculation results indicate that the Hausdorff dimension of acoustic emission signal is significantly distinguishable in the nuggets with different welding parameters. This research provides a new method for measuring the resistance spot welding quality....
2020-11-11 22:33:38浏览：56
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IN-LINE PARTICLE SIZING FOR PROCESS CONTROL IN NEW DIMENSIONS
The combination of laser diffraction with upstream sampling realized a break-through for the in- and on-line particles size analysis in industrial applications. Today, the combination of representative sampling, dry dispersion, particie size analysis by laser diffraction and integrated feedback of the sample is well accepted in many industrial applications. No more interactions of the user are required, and for standard applications the on-line monitoring of particle sizes became nearly as simple as the monitoring of any other process parameter. The increase of inspection interval from 24-hour operation to months has increased user confidence in this technology, and industries with more demanding measurement requirements are seeking to benefit from this performance. This challenge could not be solved with simple scale-ups or scale-downs. New solutions had to be found for the sampling system, the measuring sensor, the adaptation to the environmental conditions and the processing of fast growing volume of data....
2020-11-11 22:33:38浏览：59
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Experimental study on zero excess sludge production process with ozonation unit in MBR process
In order to investigate the influence factors of zero excess activated sludge (EAS) process by ozona tion, a 100 L membrane bioreactor coupled with a sludge ozonation unit (MBR-SO) was performed for 80 d without EAS wasting. Some mathematical models were developed to elucidate the relationship between process parameters and the operating effects. It is considered that the sludge lysing ratio (ζ) , produced COD per unit mass lysed MISS (η), observed sludge yield coefficient (Y_(obs)) and intrinsic yield coefficient for COD produced by lysed sludge (Y_2) significantly affect the flowrate to ozonation unit (q). When q is 0. 0067 times of influent flowrate (Q) and ζ is about 0. 72 for each batch ozonation, a relatively stable MISS concentration of 8168 mg/L and zero Y_(obs) are achieved in the MBR-SO system. The calculation of sludge disintegration number indicates that the high ζ can apparently decrease the sludge amount needed for ozonation. At the same ozone dose, the low input ozone concentration and high flowrate can enhance the sludge lysing effects and a low energy consumption of 0. 041 Yuan/m~3 wastewater is obtained....
2020-11-11 22:33:38浏览：69
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Applications of rock failure process analysis (RFPA) method
Brittle failure of rocks is a classical rock mechanical problem.Rock failure not only involves initiation and propagation of single crack,but also is associated with initiation,propagation and coalescence of many cracks.The rock failure process analysis (RFPA) tool has been proposed since 1995.The heterogeneity of rocks at a mesoscopic level is considered by assuming that the material properties follow the Weibull distribution.Elastic damage mechanics is used for describing the constitutive law of the meso-level element.The finite element method (FEM) is employed as the basic stress analysis tool.The maximum tensile strain criterion and the Mohr-Coulomb criterion are utilized as the damage threshold.In order to solve the stability problem related to rock engineering structures,fundamental principles of strength reduction method (SRM) and gravity increase method (GIM) are integrated into the RFPA.And the acoustic emission (AE) event rate is employed as the criterion for rock engineering failure.The prominent feature of the RFPA-SRM and RFPA-GIM for stability analysis of rock engineering is that the factor of safety can be obtained without any presumption for the shape and location of the failure surface.In this paper,several geotechnical engineering applications that use the RFPA method to analyze their stability are presented to provide some references for relevant researches.The principles of the RFPA method in engineering are introduced firstly,and then the stability analysis of tunnel,slope and dam is focused on.The results indicate that the RFPA method is capable of capturing the mechanism of rock engineering stability and has the potential for application in a larger range of geo-engineering....
2020-11-11 22:33:38浏览：41
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Synthesis of Nickel Sulfide Particles by Solvothermal Process
Pyrite nickel disulfide and millerite nickel monosulfide have been successfully prepared by solvothermal method based on the reaction of Ni(NO3)2.6H2O and H2NC(S)NH2 in benzene and ethylenediamine (EDA). The final products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM). The effects of the solvent, reaction temperature and time on the morphology and phase of the products have been discussed....
2020-11-11 22:33:38浏览：55
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An Empirical Study on the Impact of Automation on the Requirements Analysis Process
Requirements analysis is an important phase in a software project. The analysis is often performed in aninformal way by specialists who review documents looking for ambiguities, technical inconsistencies and incomplete parts.Automation is still far from being applied in requirements analyses, above all since natural languages are informal andthus difficult to treat automatically. There are only a few tools that can analyse texts. One of them, called QuARS, wasdeveloped by the Istituto di Scienza e Tecnologie dell'Informazione and can analyse texts in terms of ambiguity. This paperdescribes how QuARS was used in a formal empirical experiment to assess the impact in terms of effectiveness and efficacyof the automation in the requirements review process of a software company....
2020-11-11 22:33:38浏览：49
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New Method for Multivariate Statistical Process Monitoring
A new method using discriminant analysis and control charts is proposed for monitoring multivariate process operations more reliably. Fisher discriminant analysis (FDA) is used to derive a feature discriminant direction (FDD) between each normal and fault operations, and each FDD thus decided constructs the feature space of each fault operation. Individuals control charts (XmR charts) are used to monitor multivariate processes using the process data projected onto feature spaces. Upper control limit (UCL) and lower control limit (LCL) on each feature space from normal process operation are calculated for XmR charts, and are used to distinguish fault from normal. A variation trend on an XmR chart reveals the type of relevant fault operation. Applications to Tennessee Eastman simulation processes show that this proposed method can result in better monitoring performance than principal component analysis (PCA)-based methods and can better identify step type faults on XmR charts....
2020-11-10 09:33:08浏览：72
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PROCESS CAPABILITY ANALYSIS AND ESTIMATION SCHEME FOR AUTOCORRELATED DATA
Autocorrelation is prevalent in continuous production processes,such as the processes in the chemical and pharmaceutical industries.With the development of measurement technology and data acquisition technology,sampling frequency is getting higher and the existence of autocorrelation cannot be ignored.This paper analyzes five estimation schemes of process capability for autocorrelated data.Comparisons among these schemes are discussed for small sample and large sample.In conclusion,this paper gives a procedure of process capability analysis for autocorrelated data....
2020-11-10 09:33:08浏览：67
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Perturbation Solutions for Thermal Process of Honeycomb Regenerator
A parameter perturbation for the unsteady-state heat-transfer characteristics of honeycomb regenerator is presented. It is limited to the cases where the storage matrix has a small wall thickness so that no temperature variation in the matrix perpendicular to the flow direction is considered. Starting from a two-phase transient thermal model for the gas and storage matrix, an approximate solution for regenerator heat transfer process is derived using the multiple-scale method for the limiting case where the longitudinal heat conduction of solid matrix is far less than the convective heat transfer between the gas and the solid. The regenerator temperature profiles are expressed as Taylor series of the coefficient of solid heat conduction item in the model. The analytical validity is shown by comparing the perturbation solution with the experiment and the numerical solution. The results show that it is possible for the perturbation to improve the effectiveness and economics of thermal research on regenerators....
2020-11-10 09:33:08浏览：51
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Simulation of failure process of jointed rock
A modified discontinuous deformation analysis (DDA) algorithm was proposed to simulate the failure behavior of jointed rock.In the proposed algorithm,by using the Monte-Carlo technique,random joint network was generated in the domain of interest.Based on the joint network,the triangular DDA block system was automatically generated by adopting the advanced front method.In the process of generating blocks,numerous artificial joints came into being,and once the stress states at some artificial joints satisfy the failure criterion given beforehand,artificial joints will turn into real joints.In this way,the whole fragmentation process of rock mass can be replicated.The algorithm logic was described in detail,and several numerical examples were carried out to obtain some insight into the failure behavior of rock mass containing random joints.From the numerical results,it can be found that the crack initiates from the crack tip,the growth direction of the crack depends upon the loading and constraint conditions,and the proposed method can reproduce some complicated phenomena in the whole process of rock failure....
2020-11-10 09:33:08浏览：53
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