Applied Mechanics and Materials Vols. 34-35

Abstract: The purpose of this paper is to establish a criterion for the school chair surface evaluation through analyzing the rules between contour features and the comfort base on experiments. In the paper, 5 basic contour feature parameters, which are buttocks plunging depth, thigh plunging depth, buttocks contour width, buttocks contour deep and thighs contour width, are proposed. Maximum peak stress (Pm) and contact area (S) are adopted as comfort indices. The participants are 50 Chinese high school students (29 boys, 21 girls) who grouped by body size. Through carrying out the experiments of body pressure distribution at different seat contours, all participants require expressing their feeling about sitting, the effect rules of the basic contour feature parameters on seated comfort are obtained. The results shows the different value of buttocks contour deep and thighs contour width leads to varying optimal comfort points corresponding to different somatotype people. According to BP neural network, a prediction model is established. Finally a kind of school chair surface evaluation criterion based on contour is put forward.

Abstract: The working space affected workers’ security, health, comfort and working efficiency, which was an important research field of the human-machine system. According to the actual working situation of Chinese driller, the computer simulation of working space nearby driller was established. The lower limb joint angle changed in a comfortable range, which determined the area of H point, and then the regulated quantity of the driller’s chair was calculated by the computer. The working space satisfied both the short driller and the tall driller was obtained by the regulated quantity of chair, which would be taken as the restriction to carry on the human-machine interface design of driller console. In this way, the ergonomics factor was considered in the initial stage of design, and the efficiency of design was improved greatly. Finally, the CATIA human body posture analysis module was used to examine this design proposal, which proved that this method was feasible and effective.

Abstract: In this paper, based on the analysis of white noise generation, equably distributed pseudo-random numbers are generated by a method of mixed congruency. In the case that the pseudo-random numbers are taken as the phase spectrum and the amplitude spectrum is equally set, the waveform array of frequency-domain is made up. The array is transformed from frequency-domain to time-domain by the IFFT before stored into the external data memory. Based on the wave generating technology of DDS, the timer interruption of DSP2812 is installed to change the frequency for generating wave .Then the number is taken out from the external memory. The limited white noise is formed by the way of D/A and zero-section maintenance .This generator can be used as signal source in the noise simulation experiment.

Abstract: To enhance the effect of fault diagnosis, a new fualt diagnosis method based on supervised incremental local tangent space alignment (SILTSA) and support vector machine (SVM) is proposed. The supervised learning approach is embedded into the incremental local tangent space alignment algorithm, to realize fault feature extraction and new data processing for equipment fault signal, and then correctly classify the faults by non-linear support vector machines. The experiment result for roller bearing fault diagnosis shows that SILTSA-SVM method has better diagnosis effect to related methods

Abstract: Tolerance specification is the activity of specifying tolerances. In current 3D-CAD system, tolerance types and tolerance values are specified by designer manully, and the validity checking of tolerance is no available. To achieve semi-automatic tolerance specification, geometric feature in the next-generation Geometrical Product Specifications and Verification (GPS) was introduced, the corresponding rules between geometric features and tolerance types were presented; The recommended values for tolerance were stored in a database system and constrainted by tolerance principles. Additionally, the implementation of computer aided geometric tolerance specification was proposed. Finally, the initial prototype system was developed to demonstrate the proposed scheme, which aides designer to define reasonable tolerance types and tolerance values in 3D-CAD system.

Abstract: The nonlinear energy pumping in a two-degree-of-freedom system comprising a damped linear oscillator coupled to cubic damping absorber is studied. It is verified that the nonlinear pumping energy can be performed by cubic damping absorber besides cubic stiffness absorber. The resonance capture is verified by time-frequency analysis (Hilbert Transform). The energy pumping efficiency is put forward for quantitative analysis, and the optimal parameters of system are obtained. The amplitude of main oscillator can be attenuated in a very short duration. The result may be significative for engineering implementation.

Abstract: When a proper shunt circuit is connected with a curved piezoelectric membrane, its bended stiffness can be intensified. The system can be used for sound isolation. This mechatronic system， a typically multi-physics problem, was analyzed with FEM in detail. Frequency response characteristics were obtained when shunted with negative-capacitance in parallel. Transmission Loss was presented from 100Hz to 1000Hz. A wonderful sound isolation performance is obtained when shunted with proper values of negative capacitance. Negative capacitance and the loss of piezoelectric material are the main factors of the system. At some frequencies, the sound isolation performance can be increased when a compensated resistance paralleled with negative capacitance. This compensation is dependent on the frequencies. Due to its ordinary electrical parameters, the sound isolation system is realizable in practice. This sound isolation technology can be used in some fields such as windows of room and car.

Abstract: Input-output method can conveniently analyze energy consumption and environmental load for iron and steel enterprises. It can visually express production manufacturing statement and the consumption of energy and non-energy. Mathematical models are helpful for quantitative analysis and data handling. In addition, it’s useful to analyze main affected factors. Unit process energy consumption and steel ratio directly affect energy efficiency, which can be analyzed by e-p method.

Abstract: Electronic engineering budget software provides a powerful tool for the electronic engineering cost analysis, reduces the tedious hand-written budget work of the Engineer. However, to break down the project, and input into project budget software are still time-consuming works. This thesis identifies electronic engineering construction drawings using image recognition technology, automatically calculates the engineer quantities in accordance with the semantic properties of the image pixel, and finally designs electronic engineering budget software based on construction drawing recognition technology. Software application shows that the time of budget book using PRBudget is only 1% of manual preparation, and the average error of calculate is 3.89%, so it can apply to practical engineering.

Abstract: The isothermal oxidation behavior of NiAl-30.9Cr-3Mo-0.1Dy alloy has been investigated in the paper. The results reveal that Dy-addition significantly improves the oxidation resistance, which is attributed to the formation of continuously compact Al2O3 layer and rich-Cr transition layer on the surface of the tested alloy.