Papers by Keyword: Thermal Effect

Abstract: Based on the theory of point contact thermal elastohydrodynamic lubrication (EHL),the mathematical models for the thermal EHL of high-speed angular contact ball bearing are established. Multi-grid method and multigrid integration method are respectively used to calculate out the film pressure and film thickness respectively,and the column-by-column scanning method is used to calculate temperature rise of isothermal EHL and thermal EHL. The calculation results show that, under the pure rolling condition, temperature rise of oil film temperature is mainly caused by the compression work and shear heat at inlet and the heat in contact zone mainly comes from the inlet and the heat conduction around; the temperature rise results in oil viscosity lower and the lubricating film thinner ,in this way it reduces the lubrication performance in contact pair.

Abstract: The thermal effect caused by absorbing inclusion irradiated by pulse laser is affected by size of inclusions, pulse duration, repetition interval and number of pulse laser. The temperature both in the center of inclusion and the interface between inclusion and dielectric increases firstly with the increase of the size of inclusion, then trends to a constant value when the size is over the critical radius. Pulse duration and repetition interval of pulse change the energy acumulation in inclusion then have influence on the peak temperature in the center and interface. The temperature fluctuates periodically but the overall assumes the trend of increase.

Abstract: Roof greening is a promising solution for improving urban thermal environment and water quality. This paper studies the performance of a green roof with and without a self-management system, including the irrigation and shadowing subsystems, during a 3-month period via extensive experiments. Sedum plants are planted using two growing media. The first media consists of perlite and peat soil and the second media consists of average soil. Plant growth indices include vertical and horizontal growth rate as well as survival rate. Results show that a 100% survival rate can be achieved via intensive irrigation and shadowing. Meanwhile, an 8°C temperature decrease was observed during the hot season. The most suitable substrate depth is 9cm in terms of thermal effect and survival rate.

Abstract: With the rapid development of desktop computer, its motherboard power consumption has become an important factor. In this paper, experimental research under different conditions of the motherboard components is carried out. We select four kinds of load conditions of empty load, 100% load, one high-definition movie online display and two high-definition movies online display simultaneously. Through the temperature changing, its thermal effect is shown and so as to understand its heat transfer mechanism of desktop computer motherboard. From the experimental results, it is seen that, when working time more than forty minutes, the computer motherboard temperature will reach the maximum value in each operating state.

Abstract: A two-dimensional two-temperature model of shale stratum heating by high-frequency electromagnetic field is proposed. The heat exchange between solid rock and gas contained in pores is shown to significantly affect temperature field characteristics. The stratum gas filtration and reaction heat effects are taken into account as a first approximation.

Abstract: To monitor the concentration of CO accurately and in real-time in the environment with flammable , explosive and toxic gas, the intrinsic safety CO monitor with low power consumption was designed by using the low power consumption technology and intrinsic safety technology. The feasibility of the intrinsic safety design was verified by the electric spark discharge calculation and heating calculation. Low power experiments verified the low consumption characteristic of the CO monitor. This method can also be extended to the system to monitor other poisonous and harmful gases.

Abstract: The stress-strain state of impeller seal made ​​of composite material a centrifugal pump under the thermal effects is investigated based on the classical theory of elasticity of an anisotropic body. Kinematic and static conditions of contact for mating surfaces of adjacent layers are considered ideal. Solution of the problem is obtained in axisymmetric. It is noted that the increase in temperature on the surface of the composite seal has a significant impact on its stress state.

Abstract: A dental bridge, designed in STL format on a Dental Scanner software, was covered with the porcelain layer in 3-matic Design ©Materialise NV. FEA simulations were made in ANSYS ® Workbench TM ©SAS, Inc. Firstly, was performed the thermal analysis with the Transient Thermal module, and secondly, the structural static analysis with the Static Structural module. The applied masticatory force was of 300 N, and the studied temperatures were 36°C as reference and, as extremes, 0° and 50°C. The purpose was to determine mechanical effects in the bridge structure for a specific design of the dental bridge geometry in order to optimize its design.

Abstract: In this paper, an ultra-precision positioning stage is introduced. The finite element method is used to establish the theoretical model, and the strain test system of experiment is established. The system includes the static strain test and the dynamic strain test. The test system contains the software and hardware system. The software system includes the static strain measurement software of DH3816, the programmable constant temperature and humidity chamber control software TEMI300, and the dynamic strain test system developed from NI Labview. The hardware system contains industrial personal computer (IPC), piezoelectric (PZT) actuator, static strain gauge of DH3816, strain amplifier of YE1817, NI USB-6009 multifunction data acquisition card, strain gauge, programmable temperature and humidity chamber, and precision positioning stage. The experimental test is carried out to examine the theoretical analysis considering thermal effect. Experimental results and analytical results indicate that whether the stresses increase or decrease linearly or nonlinearly depend on the function of the temperature to the time during the transient response same as the stresses increase or decrease linearly during the steady response under uniform temperature change. The dynamic responses of platform are affected by the temperature change, and it is essential to consider thermal effect when analyzing compliant mechanisms.

Abstract: Recently, CFD (Computational Fluid Dynamics) is being more and more used in the investigation of the flow and thermal around high-rise buildings. In this study, prediction of thermal effect on flow pattern around high-rise buildings model located in the surface boundary layer was carried out using k-e turbulence model. Investigation of thermal effect on flow pattern behind the building and comparison between isothermal and non-isothermal building using standard k-e showed that the surface temperature of building wall led to a strong upward motion close to heating wall and decreased the reattachment length behind it. The model sittings of validation study was accomplished by comparing the simulation of wind flow around building models with the experimental data of Architectural Institute of Japan (AIJ) that results showed in weak wind region, standard k-e has good agreement with experimental.