Applied Mechanics and Materials Vols. 55-57

Abstract: We investigate the node distribution strategy in one-dimensional linear wireless sensor networks(WSNs), which aims to avoid the energy hole around the sink. We set up the network model and analyze the energy consumption factors, such as data compression and aggregation, and propose energy balance strategies due to different placement scenarios. In the uniform node distribution scenerio, based on selected optimal hop distance, we can add more backup batteries to some nodes to balance the sensors‘ lifetime. In the hop distance variable scenario, we can select different optimal hop lengths. Simulation results show that, in a WSN with linear topology, aggregation and compression should be supplied with backup battery to balance energy consumptions and to maximize the network lifetime.

Abstract: A host computer packaging cushion is designed, including deflection, buffering capacity, creep checking. Then g a three-dimensional model of the host buffer packaging systems is established Simulation of the system, including static analysis, modal analysis, harmonic analysis and transient dynamic analysis. Finally, the physical system is used to do the sine frequency, fixed-frequency sinusoidal vibration test. the vulnerability of the buffer package sinusoidal frequency calculate by the computer modal analysis larger than the resonance frequency of the measured test values This is due to host the actual shell of the computer by each side made of thin steel plate riveting, and list them in the computer simulation as a whole in the shell, so that the overall stiffness of the system become larger, so that the analysis of the inherent frequency than the actual value. Transient dynamic analysis of the computer meets the fixed-frequency sinusoidal test results，which are all happened in the prophase of vibration in the balance position. This vibration last a period causing fatigue, so that the acceleration package increases slowly and the product damage.

Abstract: Chuanxiong, as a medicinal plant, has been demonstrated useful for the treatment of cardio-cerebrovascular diseases in China. The physicochemical characterization of Chuanxiong particles was greatly influenced by ultrafine pulverization. To study the physicochemical characterization of Chuanxiong, the raw plant material of Chuanxiong was ground to 6 μm particles by HSCS (High Speed Centrifugal Sheering) pulverizer. The micron particles were characterized by optical microscope and SEM. Ferulic acid is one of active ingredients of Chuanxiong, and its extraction yield was determined to evaluate the chemical characterization of Chuanxiong powder. Ferulic acid was analyzed by HPLC (High Performance Liquid Chromatography). The results showed that after ultrafine pulverization, the plant cell walls were broken into pieces and the extraction yield of ferulic acid was increased by 7.739% compared with the normal particles.

Abstract: On ultra precision cutting, grinding and non-traditional machining, there is a hard problem between long travel and high precision. A new multi-dimension, low speed, nanometer level precision minute electric spark forming system driven by ultrasonic motors was built. A study of the basic characteristics of the ultra-precision platform driven by the ultrasonic motor was conducted in this paper. The control method of digital PID combined with bidirectional static error compensation enables the platform to realize the submicron accuracy in a stroke of hundreds of millimeters, with the minimum speed of 0.1μm/s and the minimum closed loop step of 100nm. All the achievements would provide theoretic reference to the design of these kinds of ultra precision platform.

Abstract: In view of the problems of current pantograph sliders of electric train，a new pantograph slider is developed for high speed train. The new pantograph slider is consisted of copper，carbon fiber, graphite and etc. The results showed the optimal technique of preparing slider : copper content 78％, carbon fiber content 2％, additive content 5％, pressure 200MPa and sintering temperature 880°C. Its resistance is very low. And its performance of friction，abrasion and impact toughness etc. is improved greatly compared with foreign immersed metal carbon slider Rh82Mb with friction coefficient reduced by 20 %，abrasion ratio decreased by 1.3 %，impact toughness increased by 1.7 times and conductance increased by 65 times.

Abstract: The grassland ecosystem of HulunBuir city is an important component of ecology security system in Northeast China. In this study, net primary productivity (NPP), as an improtant ecological parameter, was used to estmate the services value. Considering the characteristic of satellite imagery, it is difficult to calculate some functions. So we calculated the services value from 6 aspects, including soil erosion control, water conservation, direct production, gas regulation, nutrient recycling and atmospheric environment purification. The total services value of grassland ecosystem was estimated in RMB to be aproximately 18.47×10⁹Yuan in 2006, the average economic value of unit area was 15.4×10⁴Yuan/km². The direct production value was 1.23×10⁹Yuan/year; and the contribution rate to total value was 6.66%. The water regulation value was the maximum, 9.09×10⁹Yuan/year. Gas regulation value was 5.25×10⁹Yuan/yea. The purify atmosphere value was minimal.

Abstract: Zero-valent iron (ZVI) nanoparticles are prepared by wet chemical method, unlike conventional methods, we applied a water-soluble dextrin、CMC and starch in the preparation. The starch serves as a stabilizer and dispersant that prevents the resultant nanoparticles from agglomeration, and characterized by XRD、SEM and USP. Compare the dispersion of particles and particle size in progress of reducing. According to the characterization results, the nanoparticles can be dispersed more efficiently, maintained the activity of it owned and kept the stability longer with the dispersing agent. Based on the results obtained, the starch as a dispersion agent on the preparation of Zero-valent iron (ZVI) nanoparticles is an ideal approach.

Abstract: The aim of this work is to study the influence of beating and refining as well as the fibre furnish on the properties of silk paper, such as air permeance, softness, pore size, tensile index and burst index. The results showed that the beating characteristic of silk fibre was similar to that of plant fibre, they all had the characteristic of fibrillation. Silk paper had excellent softness and air permeance when the beating degree of silk pulp was 20 °SR, 181.3 μm/Pa·s and 2.5 mN·m²/g respectively, which was superior to paper made from plant fibres of the same beating degree. The minimum average pore size of silk paper was 5.11 μm at the beating degree of 20 °SR, and it decreased with the increase of beating degree, reached 0.79 μm at the beating degree of 67 °SR. With the increase of beating degree, the tensile index of silk paper increased at first, and then decreased. The burst index of silk paper showed a upward trend, but the softness and air permeance of it constantly decreased. The tensile strength of paper made from mixed-furnish pulp consisting of silk and softwood reached the maximum when the amount of silk fibre was 4%, and its air permeance increased with the increase of silk fibre.

Abstract: In the process of weld seam tracking, traditional mathematical model of classical and modern control theory is hard to meet the requirement of high performance controller. This article based on the embedded digital signal processor DSP-TMS320F2812 for the field of industrial automation control.The fuzzy control technology is applied to real-time welding seam-tracking system, according to the F2812 which has the characteristics of real-time multitasking scheduling of resources and then designed the real-time control value adjustment Fuzzy-PI control system. The designed DSP real-time fuzzy control system gives full play to powerful control and signal processing ability of F2812, it can fully adapt for the controlling requirement of super-speed and high-precision.

Abstract: The copper/paraffin nanocomposites were synthesized by high energy ball milling. Observation of the microstructure, comparison and ascertainment of the particle size of the composite were analyzed by transmission electron microscope. Then the composite was put into a home-made copper tube (5 mm in diameter, 20 mm in length, closed at one end) by thermoforming process, and its thermal sensitivity was measured using thermo-controlled optical micro measuring equipment. The effects of milling time on the microstructures and the thermal sensitivity of copper/paraffin nanocomposites were investigated. The results showed that different milling time caused the changes in particle size and shape of the composite, and had a significant effect on its thermal sensitivity. With increasing milling time, the thermal sensitivity of composite gradually increased.