Applied Mechanics and Materials Vols. 130-134

Abstract: A numerical study on the interaction of water mist with a fire plume was conducted using FLUENT software. The effects of different mist characteristics, such as droplet size and spray intensity, was considered in this simulation. The fire plume temperature history and velocity field were investigated. The results show that with a certain droplet size of water mist, the extinguishing time will be shorter when the mass flow of water increases, but this effect is no longer distinct after the mass flow of water mist increased to a critical value.

Abstract: In this paper, we focuses on combustion characteristics of the mixed gas of methane/air in the ring porous medium burner using numerical simulating method. The influencing factors of combustion, such as different methane/air ratio, the velocity of flow and heat loss of internal and external wall, are discussed, and it is shown that the ring porous medium burners have some advantages different from straight or rectangular porous media burners. Due to annular asymmetric structure, the temperature distribution of ring porous media burners are more uniform, and are no unfavorable phenomena such as the local high temperature and the hot spots. The simulation results for annular porous medium provides important theoretical basis for the development of new porous medium burners.

Abstract: In this paper, a simple combustion facility was simulated numerically with FLUENT code to investigate the process of coal combustion, NO_x formation, and SNCR for NO_x removal. The influence of the temperature and ratio of NH3/NO on NO_x removal efficiency was researched by the numerical simulating of SNCR process. The simulation results are helpful for the optimization design of SNCR system.

Abstract: The present study investigates theoretically the effects of gasoline fumigation on single-cylinder diesel engine performance and emissions. The results indicate that a premixed charge can be obtained by early injection of gasoline because of the high volatility of gasoline. More homogenous mixture was obtained and the fuel burned faster and efficient. The smoke emission was reduced and engine output was increased. Coupling with EGR technique could reduce the NOx emissions simultaneously.

Abstract: Lean-burn engines operate at a very lean air-to-fuel (A/F) ratio under light-load and part-load regions, in order to analyze the effect of engine speed and load on the BSFC (Break Specific Fuel Consumption) and exhaust emission of Lean-burn engine, an experimental research was conducted on a 4 cylinder lean-burn gasoline engine using different A/F ratios. The results show that the CO emission level decrease significantly, HC emission level becomes lower at the same A/F ratio, while the NOx emission increases, hence, advanced technologies are needed to carry out the NOx storage and purge operations in the lean-burn engines. Additionally, the experiment also reveals that the BSFC becomes lower as the engine speed and load increase.

Abstract: The main components of a space helix TWT (traveling wave tube) are electron gun, helix slow-wave system and collector. Thermal issue is of great importance for space helix TWTs. High heat efficiency of cathode is required for electron gun, as well as high heat transmission capacity for slow-wave system and collector. Some structure optimization for the electron gun, slow-wave system and the collector of some type of space helix TWT has been proposed aiming the above purpose. To evaluate the structural optimization means, the related thermal analysis has been carried out using ANSYS software. The simulation results demonstrate that the structure optimization is effective. And the actual effect needs to be further studied.

Abstract: The economic downturn has been forcing many companies to use predictive analysis for spotting emerging product and technology trends and also future customer needs. Since every company is unique, without the assistance of some methodologies and tools, decision makers encounter great difficulties in conducting predictive analysis, especially in the deliberation and prioritization of new prediction criteria derived from the publicly available unstructured information. This paper proposes a unique methodology which attempts to integrate the personalization and visualization of new prediction criteria. The challenging iterative tasks are achieved through a rule-based inconsistency detection triad-based comparison algorithm, supported by sophisticated visual displays of the relative importance among the prediction criteria. It is hoped that the proposed methodology will intuitively support the decision makers in exploring and deliberating new criteria for making better predictions.

Abstract: In this article, the one time rotation of a body of revolution to the designated position under any conditions is studied, especially when the rotating front and rear of a body of revolution are on different planes, in which case, descriptive geometry graphic solution is employed to solve the rotation axis and rotation angle. Compared with other methods, this method is simpler and more visible. The solution of the problem will greatly contribute to the simplification of production processes, thus lowering product costs and improving economic benefits.

Abstract: Despite the abundance of analysis techniques to discover control-flow errors in workflow designs, there is hardly any support for data-flow verification. Most techniques simply abstract from data while data dependencies can be the source of all kinds of errors. This paper focuses on the discovery of data-flow errors in workflows. There are many issues in the dataflow, like Redundant Data, Lost Data, Missing Data, Mismatched data, Inconsistent data, and Misdirected data. We present an analysis approach that uses so called “The RWD Boolean Table Technique” expressed in steps, I Split dataflow from control flow; II Create Boolean table for each data element/s; III Make comparative between RWD Boolean table for current task and next task until get the end of workflow; Typical errors include dataflow issue, like redundant Data, lost Data and missing Data.

Abstract: Conical valve’s spool-seat contact pairs is consisted of two surfaces of different curvature radius, and form closed circular contact line. It can be considered as the model of elastic hemi-space contact by the Hertz Theory. The numerical simulation and experiment show: The model is suitable for the analysis of conical valve’s spool-seat contact pairs. The conical valve’ sealing performance is very credible and its performance is very good. Maximum stress is smaller than allowable stress of the seat’s material. The consistency of experiment and simulation proves the validity and practicability of the hemi-space contact model of the valve’s spool-seat contact pairs.