Applied Mechanics and Materials Vols. 80-81

Abstract: This paper presented results of a study on emission characteristics of diesel engines. A numerical simulation model for a diesel engine was established by GT-POWER. Emission species studied include of NO, CO and HC. The developed model was validated by engine tests under laboratory condition. Based on the model, the simulation changing the variable parameters including injection timing, intake air temperature and EGR (exhaust gas recirculation) ratio were carried out to study their effect on emissions. The simulation results showed that with the decrease of CA BTDC, intake air temperature, compression ratio and EGR ratio respectively, the NO emission decreased. However, the CO and HC emissions increased.

Abstract: Orientin, isolated from bamboo leaves, is an important natural antioxidant. It has been identified that orientin could protect myocardium against ischemia/reperfusion (I/R) injury, and mitochondrial pathway might be involved in this effect. But the precise mechanism underlying this protective effect is still elusive. Mitochondrial channels are proved to be the important effectors of cell life and death. Especially, mitochondrial calcium uniporter (MCU) has shown particular contribution to cardiomyocytes under specific pathological or physiological conditions. The role of MCU in regulating I/R-induced heart injury is a novel research area. In addition, the relationship of orientin and MCU in mediating reperfusion-induced cardiomyocytes injury is still elusive. In the present study, we used H9c2 cardiomytocytes to investigate the effect of orientin on MCU during reperfusion. Our results indicated that orientin could prevent the MCU opening in H9c2 cells subjected to I/R injury. Further investigation revealed that this effect was correlated with orientin-attenuated reactive oxygen species (ROS) production, depolarization of mitochondrial membrane potential (Δψm), mitochondrial cytochrome c release and mitochondrial Ca2+ accumulation. Our results suggested that these beneficial effects of orientin were partially blocked by spermine, an activator of MCU. In summary, the findings indicate that orientin protects H9c2 cardiomytocytes against ischemia/reperfusion injury via inhibiting mitochondrial calcium uniporter opening，and PI3K/Akt signaling pathway may be involved in these effects of orientin.

Abstract: Battery management system (BMS) is the most important part of an electronic vehicle (EV), and the management module for single cell is the most important collection part of BMS. It provides cells’ data and realizes cells management for BMS. In this paper, the design and realization of the management module for single cell is presented. It can collect real-time voltage and temperature data of cells, and carry on the necessary processing for such data, and then upload these data to the main control module in the battery management system. The design can also equalize the cells, and made their voltage remain in a standard. For the proposed design scheme, the microcontroller PIC24F16KA101 is used as the core part, and the multi-cell addressable battery stack monitor LTC6802 is utilized as the collection part. Moreover, the design of multi-channel data collection and management system, and the design of software and hardware for interface are given. The practical experimental results show that the system can realize the real-time multi-channel signal collection, offer useful data for battery management system, and equalize the cells at power on or power off situation, so as to guarantee the battery consistency.

Abstract: Thermal design and the working temperature control have been a key factor in the design of electronic devices and system. In this paper, a sort of heat sink collocated with high-power IGBT module, which is commonly used in car-carrying motor control system, is designed based on thermal analysis by means of CFD simulation and computer-aided analyzing, also the influence relations of structure parameters with thermal performance are studied. With thermal control as the overall design objective, structure parameters of heat sink are determined according to the obtained relations. Further, thermal performance of the designed heat sink is simulated and analyzed in CFD software to examine the validity of the design result. In this way, a method of thermal analyzing and structure parameter design for heat sink, which is proved as an efficacious approach, is introduced and can be used to thermal design and analysis for similar products.

Abstract: In this study, we restrict our attention to shape optimization of a body immersed in the Navier-Stokes fluid flow. The formulation and numerical results of the proposed method are presented. The proposed method is based on an optimal control theory. The optimal state is defined by the reduction of drag forces subjected to the immersed object. The cost functional should be minimized is governed by the Navier-Stokes equations. The shape sensitivity analysis of the cost functional was derived based on the adjoint method. Finally, a numerical example is given to show the feasible for the proposed algorithm.

Abstract: Aiming at the problems existing in the process of shearing such as bad-section quality and low efficiency, several parameters have been changed in experiment research in the text, which is good for the wide application of this shear technology. The results of experiment agree well with shear theory.

Abstract: The diffusion combustion of the air heater was numerically simulated at different excess air coefficient using Fluent software. The distributions of the temperature, gas flow velocity, and turbulence intensity were present. And the heat flux was calculated. The result showed that the excess air coefficient had a little effect on the maximum combustion temperature distribution. As the excess air coefficient increased, the axial temperature at first increased and then decreased, and in contrast both the total heat flux and radiation heat flux decreased. The radial temperature, velocity and turbulence intensity increased firstly and then decreased at the same operation condition. The measured exhaust temperature increased with time. At 90 second, it was about 250 °C, which showed good agreement with simulation result. This provides theory basis for the reform of the heater.

Abstract: To investigate the property of a new type of Zircaloy material, a low cycle fatigue (LCF) test has been performed at room temperature (RT) and 375°C. Results show that the new alloy generally displays cyclic hardening followed by a continuous softening behavior. Fatigue lifetime curves as a function of strain range imply that the new alloy has a nearly same lifetime than that of Zr-4 at RT, and superior than that at 375°C.

Abstract: In this paper, a kind of joint structure which can connect rigid pipe with flexible pipe in seabed longtime was designed and its characteristics were analyzed. The structure can be immune to seawater’s fluctuation or erosion, where the stress concentration at the joint of rigid pipe and flexible pipe was reduced to ensure pipes safe. The joint structure has low cost and highly reliability, which was helpful to exploitation in deep sea.

Abstract: Hyperspectral data is endowed with characteristics of intrinsic nonlinear structure and high dimension. In this paper, a nonlinear manifold learning algorithm - ISOMAP is applied to anomaly detection. Then an improved ISOMAP algorithm is developed based on the analysis of the inherent characteristics of hyperspectral imagery. The improved ISOMAP algorithm selects neighborhood according to a novel measure of combination of spectral gradient and spectral angle in order to make the algorithm more robust to the changes of light and terrain. Experimental results prove the effectiveness of the algorithm in improving the detection performance.