Advanced Materials Research Vols. 482-484

Abstract: The corrosion behavior of Zn27Al3Cu in 3.5 Wt.% NaCl solution is investigated through weight loss method. The morphology of corrosion products were observed and analyzed with optical microscopy (OM), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The experimental results indicate that weight loss of the alloy with time follows the exponential attenuation relationship. Corrosion mechanism of Zn27Al3Cu alloy are intergranular corrosion and preferential corrosion in 3.5 Wt.% NaCl solution, the main corrosion products are compound oxide and chloride.

Abstract: Adaptive tracking sinusoidal signals with time-varying frequency buried in white noise presents a great interest in engineering applications. A simple approach of application of adaptive notch filters (ANFs) in recursive identification was presented. The use of adaptive infinite impulse response (IIR) notch filters is exploited to detect the sinusoidal components in noise as far as the two-stage vibration isolation system. Computer simulations and experiments on real signals generated by the two-stage system vibration isolation demonstrate the advantage of this method in terms of estimation variance, convergence speed, and the capability of tracking the signals.

Abstract: Purposes: To investigate the condition of compliance of left-home children. Methods: 345 left-home children (144 males, 201 females) were measured by the Gudjonsson Compliance scale (GCS). Results: There are significantly gender differences in compliance among left-home children (P< 0.01); there are significantly differences in compliance between only-child and non-only-child left-home children (P<0.01); there are no significantly differences in compliance between the left-home children who come from urban area and rural area left-home children( P< 0.01). Conclusion: There are significantly differences in gender, between only-child and non-only-child, and from urban area and rural area left-home children.

Abstract: This work presents a highly integrated multi-functional, multi-waveform signal generator which can generate various waveforms, with digital controller inside to adapt embedded and low power applications. The proposed system uses Nios II, a reconfigurable, programmable and optimizable soft-core embedded CPU together with modern EDA tools to accomplish system HW/SW co-design and implementation. Utilizing characteristics of Nios II, we put together core and peripheral logical units that system needs and implant them into a single FPGA chip, then uses the Avalon bus to connect peripheral modules (such as function switch buttons and 7-segment LED display units) to Nios II's Avalon bus main port (instruction and data control port). The realized system is flexible to reduce, extend, with low power consumption, and has System on Programmable Chip (SOPC) function which means the system’s software and hardware is online programmable.

Abstract: Abstract. This paper is regarding research concerning Taiwan’s High Speed Railway (THSR) service; its quality and performance. Most of the passengers preferred this transportation when compared with other trains because it is clean, convenient, comfortable, and saves time, while offering high quality service. The paper has 5 service quality dimensions. It includes 28 items in the form of a questionnaire for passengers which focused on the Hsichu station. The first dimension concerns boarding the train; the second is inside the train station; the third is on the platform; the fourth is riding the train, and the last one is leaving the THSR station. The analysis shows the Strengths, Weaknesses, Opportunities, Threats (SWOT) and the Importance Performance Analysis (IPA). The research is in regard to passenger’s satisfaction with the quality of service and customer satisfaction.

Abstract: A switch-mode power amplifier based on a cascaded multicell multilevel circuit topology is introduced in the paper. Due to the Carrier-Based phase-shifted modulation of the individual switching cells, the output voltage ripple of the total system is considerably small. Compared with traditional class- AB amplifiers that are very poor at efficiency, the proposed amplifier has the efficiency of 90% at the smaller distortion level. A multilevel class-D amplifier’s mathematic model is analyzed. The paper lays emphasis on the design of the sliding mode control and deducts the parameters, and then develops a 2kW cascade multilevel class-D power amplifier adopting sliding mode control. The research results show that this kind of amplifier increases the system bandwidth, which provides the system with fast following performance and stability, high efficiency, and low THD value of output signals.

Abstract: Thin-film nanofiltration composite (TFNFC) membrane consisting of polyethersulfone (PES) nanofibrous support layer modified by 3, 4-dihydroxy-phenethylamine (dopamine) and interfacial polymerization (IFP) polyamide selective barrier layer was obtained in this study. The hydrophilicity of PES nanofibrous membrane was tremendously improved as the water static contact angle changed from 81.6° to 26.83° by dopamine modification. An ultrathin selective layer was produced by IFP reaction between solutions of piperazine (PIP) and trimesoyl chloride (TMC) on the dopamine modified porous PES membrane. The TFNFC membrane presented relatively high permeate flux (~59.9 L/m2h) and high salt rejection (~98.9%) to divalent anion solutions (1000mg/L, Na2SO4) at a low pressure of 0.6 MPa. It could be believed that dopamine modification would be very efficient to fabricate the composite membranes with stable structure and high filtration performance.

Abstract: Gaussian mixture model background difference method is an effective method to achieve the moving target detection. According to its deficiencies of accuracy, speed and other aspects, this paper presents an improved Gaussian mixture model background difference method. Firstly, use three-frame difference method to detect the alterant area rapidly by the advantages of accuracy and fast speed. Then, use the area method to judge the results, and determine whether it is need for target extraction of the current frame by Gaussian mixture model background method, which can reduce the time of object detecting and background modeling. Meanwhile, the update strategies of the Gaussian mixture model background is improved, which can further enhance the detective accuracy and speed for the large and slow moving targets.

Abstract: Strain rate change tests were performed under uniaxial tension-compress cycle loading during low cycle fatigue of AZ91D magnesium alloy using plastic strain as the control variable. Results show that the cyclic softening phenomenon is appeared in testing materials when cycle strain amplitude is less than 0.4%. With the increase of the cyclic strain amplitude, material displays obviously cyclic hardening; at the same time, the additional strengthening degree of materials is increased. Further study found that the slope of the curve is unchanged when the strain amplitude is more than 1.0%. The changes of strain rate has a little impact on the low cycle fatigue life of AZ91D magnesium alloy, conversely, the changes of strain amplitude has a great influence on low cycle fatigue life on the material. With the improvement of strain amplitude, fatigue life is reduced obviously. In addition, the Coffin-Manson formula fitting equation has good consistency with the experimental data, which is used in low cycle fatigue prediction life.

Abstract: Due to its convenience, quickness, cheapness and so on, NATM is widely used in the tunnel excavation. In order to guarantee security when tunnel construction and study the stability of tunnel surrounding rock, Supervision and measurement is essential in the tunnel excavation, the result of which may influence tunnel excavation directly. Based on the analyses of measured data, the distribution characteristics and variation laws of the ground settlement, crown settlement and convergence around the tunnel, the displacement of the interior of surrounding rock are all studied. The study results are drawn to provide the basis for modifying and optimizing the design and construction scheme.