Applied Mechanics and Materials Vols. 157-158

Abstract: Total hardness is an important index to evaluate drinking water quality. Total hardness in drinking water was determined by micro titration and conventional titration seperately and parallel determination results of microscale chemical laboratory and constants experiment were compared. The results of micro titration were accurate and reliable. Microscale laboratory has such characteristics as obvious phenomena, saving reagents, fast analysis. So the cost was reduced and the innovative ability of students was improved by full compliance with the concept of green chemistry. Microscale laboratory is worth promoting.

Abstract: A system with low-cost, low power consumption and wide range of ultrasonic positioning was designed. The node layout is the ultrasonic transmitter vertically installed on the top of the metal can as unknown node, the ultrasonic receivers as beacon nodes, 4 nodes installed on the ceiling and 4 nodes installed on the floor fixed position to receive ultrasonic. Ultrasonic sensor was designed with low power consumption microcontroller Ti MSP430F1611 and RF transceiver chip CC2420. Effective range is 10m, accuracy ± 2cm, launch angle , the system power 200 ~ 400uA/MIPS, 5V lithium battery-powered, Zigbee wireless communication protocol for data transmission. A new algorithm of node location module and Matlab software simulation result were established to achieve 3D seamless positioning of metal can in 20m*2m*2m indoor space.

Abstract: Bending cyclic fatigue tests of 2D laminated C/C composites were conducted under load control at a sinusoidal frequency of 10 Hz. And three-point bending tests of fatigued specimens with various cycles were conducted at room temperature to evaluate the effects of cyclic load on mechanical properties. 2D C/C specimens were prepared by an isothermal chemical vapor deposition (CVD) process. The mechanical properties of composites were improved after cyclic loading at most the flexural strength by about 46% and the modulus 38%. The results show that the flexural properties of C/C composites were enhanced with the increase in fatigue cycles. It is suggested that the weakened interface between matrix and fibers by cyclic load play important roles in enhancing the property of C/C composites.

Abstract: In recent years there has been a growing interest in the study of sparse representation of signals. The redundancy of over-complete dictionary can make it effectively capture the characteristics of the signals. Using an over-complete dictionary that contains prototype signal-atoms, signals are described as linear combinations of a few of these atoms. Applications that use sparse representation are many and include compression, regularization in inverse problems, Compressed Sensing (CS), and more. Recent activities in this field concentrate mainly on the study of sparse decomposition algorithm and dictionary design algorithm. In this paper, we discuss the advantages of sparse dictionaries, and present the implicit dictionaries for signal sparse presents. The overcomplete dictionaries which combined the different orthonormal transform bases can be used for the compressed sensing. Experimental results demonstrate the effectivity for sparse presents of signals.

Abstract: In order to analyze the impact factors of slip strength in clamp devices for tunnel rigs in coal mine comprehensively and quantitatively, a multi-factor and hierarchy index system with 13 indexes were established, including 4 fields of driller, construction characters, technology and environment. Fuzzy Analysis Hierarchy Process (FAHP) was used to analyze slip strength. A simple method to construct fuzzy consensus matrix was introduced to obtain the weight of different factors. Result shows that FAHP is validated to be used in slip strength impact analysis.

Abstract: The conclusions can be acquired by experimental study and theoretical analysis.Owing to arching action,limit load of reinforced concrete frame beams can be enhanced largely.With the increase of the load rate,the limit carrying capacity of reinforced concrete frame beam and axis force also raise,but the ductility of the components falls.Theory results are basically consistent with experiment results,error is in allow bound.

Abstract: As an important supporting component of thrust bearing of hydropower plant, the elastic oil sump plays a vital role in the safe operation of the hydropower plant. Considering the complicated working conditions of the elastic oil sump, it is of great significance and convenience to use a method of CAE to simulate the actual working state of it. In literature, many researchers have investigated static behaviors of the elastic oil sump. However, a dynamic analysis of the oil sump has been seldom investigated formally yet. Therefore, in this study we particularly focused on investigating the dynamic behaviors of a single corrugated elastic oil sump. In this study, the finite element model of the studied oil sump is built with reasonable simplifications of the working status. Then, static and dynamic analyses of a single corrugated elastic oil sump are performed by the means of ANSYS software. Performance parameters of the sump, the initial oil pressure and dangerous region are determined through the static analysis. In the dynamic analysis, the time-history curves of VM equivalent stress and 1st /2nd/3rd principal stress of a tracked node in the crucial region are obtained. The results showed that the method of finite element analysis (FEA) suits well in the study of the stiffness properties of the elastic oil sump and the stress cycle is big enough to induce fatigue damage to which should be paid close attention.

Abstract: Rotating discs are used widely as important structural elements in mechanical engineering. In order to obtain an optimal structural design, it is necessary to estimate the angular velocity and the stress distribution of a rotating disc in fully plastic state. So J2 deformation Theory is used for large deformation analysis of axisymmetric rotating disk. The bursting speed of rotating disk, the stress distribution at instability and analysis on the elastic-plastic interface of rotating disk are studies in detail.

Abstract: Aiming to discharge feebly, improving the frequency of MEDM power pulse is an ideal choice. But due to the influence of power resistor, capacitor, inductor with stray capacitance and stray inductance, increasing the higher pulse power frequency met bottleneck. Through the analysis of MEDM discharging circuit and routes, this paper puts forward the theory of not using components, but depending on the natural oscillation of MEDM machine tools and connection line to make MEDM pulse power. Through theoretical calculation and simulation, the oscillation period of discharging circuit can be controlled in 1.5ns, and the pulse width can be less than 750 Ps. It provides theoretical support for making picosecond pulse power and nanometer manufacturing with MEDM.

Abstract: The applicability and accuracy of whole set oil-immersed pump lectotype are the key points to improve the recovery ratio of oil field and to conserve energy. This paper have conceived the construction and implementation of the expert system of whole set oil-immersed pump lectotype and discussed in several aspects: such as systematic analysis and design, the construction of engineering control platform, the development of plug-in software, the construction of intelligent system and the execution of software design and so on. It has integrated the synthetic approach with expert System of Whole Set Oil-immersed Pump lectotype.