Applied Mechanics and Materials Vol. 461

Abstract: On the basis of the principles and characteristics of the various switching power supply, we have designed a high-power supply which can be used for the magnetic resonance sounding equipment for detecting mine ground water. The characteristics of the switching power supply are the full-bridge converter as the main power topology and the SG3525 chip as the core of the control. The high frequency PWM signal generated by the SG3525 can drive the four power switch tubes of the full-bridge circuit to conduct alternately thought the IR2110, so we can get continuous and stable DC output voltage. The design of the switching power supply has a lot of advantages, such as high efficiency, low noise, high stability, and small volume weight.

Abstract: Presently there are some challenging technological problems which severely restrain the progress of oil/gas development and production. To address these existing specific challenges, solutions enlightened and obtained from bionics have been applied. This paper reviews the applications of the most influential bionic technologies in the oil/gas development and production engineering, which include bionic non-smooth surface, shape memory polymer, bionic porous material, etc. Some successful field applications of these bionic technologies are described in detail, e.g. the application of the non-smooth theory in the solid expandable tubular technology to reduce friction resistance, and the utilization of bionic porous material as sand control screen to effectively improve sand retention and reduce the influent resistance. The vision of the potential bionic technologies, such as bionic inflow-control devices and nanorobots are also discussed.

Abstract: Based on the characteristic of an ultrasonic sensor that can sense the external environment, we design an intelligent vehicle with obstacle avoidance function. First, we use MSP430 as the core of the design system. Second, we distribute the ultrasonic sensor evenly on the round zone of the obstacles to process the data and ambient temperature, which is transmitted from the ultrasonic receiver through the SCM (what is SCM, explain). Finally, we make it to realize the functions of intelligent controlling and avoiding obstacles automatically.

Abstract: Subsoiling, as an important mode of conservation tillage, can break plowpan and increase permeability and water retention ability of soil which increase the crop yield. Subsoiler, as a key component of subsoiling, significantly effects on the tillage resistance. Reduction of working resistance of subsoiler can decrease output power of tractor and then further reduce the cost of subsoiling operation. The existing subsoilers have problem of overlarge subsoiling resistance. The conventional methods to resolve such problem include optimal design of the structural parameters of subsoiler and application of oscillation subsoiling device, but those methods not only make the structure of subsoiler more complex, but also increase the cost of agricultural production. Based on biomimetics principles, the upper surface outline of the claw of the house mouse (mus musculus), which has exponential function curve feature, was applied to the structural design of cutting soil edge of subsoiler shaft. Accordingly, the bionic subsoiler which has exponential function curve feature was designed and manufactured. The comparative experiments were conducted using the two types of subsoilers which have exponential function curve shape and parabola type in tillage depth at 300mm and 350mm with the forward velocitys of 0.5m/s and 1.0m/s in the indoor soil bin. The horizontal tillage resistances of the two types of subsoilers were measured using remote-measuring system of agricultural machinery dynamic parameters under different experimental conditions. The results showed that the horizontal tillage resistances increased with the increase of tillage depth and forward velocity. The horizontal tillage resistances of bionic anti-drag subsoiler (BAS) were obviously less than those of parabola type subsoiler (PTS) under same experimental conditions and the reduction was in the range of 8.5-38.2%. It indicated that the cutting soil edge of shaft with exponential function curve structure has remarkable anti-drag property. The simulations of tillage processes of the two types of subsoilers were conducted using discrete element method (DEM), the stress fields and velocity fields were obtained under different simulation conditions. The results showed that the directions of stress fields and velocity fields of the two types of subsoilers have forward and upward variation trend, but the directionality of contact stress of PTS was nonuniform compared with BAS, and such results lead to an increase in soil disturbance. The intensities of stress field and velocity field of BAS were obviously less than those of PTS under same experimental conditions, The results of simulation were consistent with the results of tillage experiments, indicating that the bionic subsoiler with exponential function curve feature has significant anti-drag property. The exponential function curve can be applied to the structural design of cutting soil edge of subsoiler aiming to reduce tillage resistance.

Abstract: Nearly 40% of Chinese water pollution comes from agricultural sources of pollution, and the annual emissions are difference. If we want to control pollution emissions effectively, we need to accurately predict the amount of agricultural emissions of Ammonia Nitrogen (AN) and Chemical Oxygen Demand (COD). Due to the complex mechanism of the agricultural non-point source pollution, its emissions are very difficult to measure. Currently, the Bionics Research is in a stage of rapid development, and it continues to expand into many new areas of research. So the comprehensive study of Bionics and pollutant control study will be a good choice. This research used bionic BP（Back Propagation） neural network algorithm, and used pollution census data from 2002 to 2007 and established neural network model with neural network algorithm. And we predicted the agricultural sources of emissions of AN and COD with the data from 2008 to 2010. Finally we compared the predicted value and the actual value. Research results showed that, with using the bionic BP neural network, agricultural sources emissions of AN and COD are evaluated actually and the results indicate that the average error is under 5.0%. Research results proved that the model is effective. The neural network is a scientific predict method for the agricultural sources emissions of AN and COD. It can be widely used in the prediction of agricultural sources emissions of AN and COD.

Abstract: Soil adheres to the surfaces of soil engaging components of earthmoving machinery and equipment. It has been pbserved that up to 50% of energy may be consumed in overcoming adhesion and friction of soil to the surfaces of soil engaging components of agricultural and earthmoving machinery. Surface morphology, chemical composition, elasticity, lubrication mechanism and electric osmosis play significant roles in reducing adhesion, friction and energy consumption of various equipment. Some of these techniques have very limited application in the practical field conditions because of the time and amount of fluid required to achieve the desired results. Whereas other techniques are effective in reducing adhesion and friction and improving work quality of these machines and equipment. This paper analyses the forces including the drafts of conventional and bionic bulldozing blades operating under identical conditions using mathematical modelling. The force analysis showed that both adhesion and friction play major role in reducing drafts of earrthmoving machinery. It is also worth stating that both the surface morphology and the construction materials play important role in reducing adhesion and friction of ground eganging components of earthmoving machinery.

Abstract: Brain-machine interfaces (BMIs) decode cortical neural spikes of paralyzed patients to control external devices for the purpose of movement restoration. Neuroplasticity induced by conducting a relatively complex task within multistep, is helpful to performance improvements of BMI system. Reinforcement learning (RL) allows the BMI system to interact with the environment to learn the task adaptively without a teacher signal, which is more appropriate to the case for paralyzed patients. In this work, we proposed to apply Q(λ)-learning to multistep goal-directed tasks using users neural activity. Neural data were recorded from M1 of a monkey manipulating a joystick in a center-out task. Compared with a supervised learning approach, significant BMI control was achieved with correct directional decoding in 84.2% and 81% of the trials from naïve states. The results demonstrate that the BMI system was able to complete a task by interacting with the environment, indicating that RL-based methods have the potential to develop more natural BMI systems.

Abstract: The study of vestibule neurons specific firing mode of Gekko gecko under stimulus of different angles and rotating speeds has an important theoretical significance to reveal the control mechanism of Gekko geckos vestibular position as well as to the development of gecko-robots. A vari-angle rotating equipment was made to give different stimulus in study of Gekko geckos vestibular electrophysiology. The equipment mainly consisted of four parts as follows: fastening panel for stereotaxic instrument, shaft locking device, counterweight, driving system. The shaft locking device and counterweight realized tight fixation and torque equilibrium at different angles respectively. Fastening panel matched the general stereotaxic instrument. A stepper motor driver controlled the velocity and acceleration of rotation. Initial experiment verified that the equipment had superiority of easy operation, reliable positioning and accurate control of angle and speed, which indicated that it could meet the demand of the Gekko geckos vestibule research.

Abstract: A good designed MEMS microphone is very important for attaining good characteristics of sensitivity and frequency bandwidth with flat response. So we performed multi-physics finite element analysis that can predict an electro-mechanical behavior of MEMS microphone. Then we fabricated the well-designed MEMS microphone with using micromachining technique. The fabricated MEMS microphone was consisted with low stress poly-silicon membrane and electroplated back-plate. The simulation of sensitivity and frequency response of packaged MEMS microphone was carried out. The simulation results show the acoustic sensitivity of -40.91 dB and the cutoff frequency of 79.4 kHz, respectively.

Abstract: Multi-nodes inertial data acquisition has the widespread applications in medical rehabilitation research and biomechanical analysis. In the traditional method, the inertial data of every child-node is sent to a center node by wired line firstly. Then the center node transfers the data of all child-nodes to PC through a single serial port. This approach has some obvious drawbacks, including the fact that the sampling rate is low, the communication protocols are complex and installation is inconvenient. This article proposed a multi-node and multi-base-station wireless data acquisition system. The communication between child-node and the base-station is performed in a point-to-point manner. The data of micro inertial sensors on the child-node circuit board is collected by the MCU then is sent to the matching base-station by the RF module. The base-station send data packet to the upper computer through serial port. The results showed that the upper computer software can collect data packets synchronously from three child-nodes (the data packet of each child-node contain 19 Bytes) with high-speed sampling rates up to 118 Hz. And there is no obvious deferring time under this condition. The technique has the certain applications in the data collecting system of motion capture. Key words: Pcomm; multi-thread; multiple serial ports; nRF905; MPU6000