Evaluation of constructed wetlands by wastewater purification ability and greenhouse gas emissions.

Domestic wastewater is a significant source of nitrogen and phosphorus, which cause lake eutrophication. Among the wastewater treatment technologies, constructed wetlands are a promising low-cost means of treating point and diffuse sources of domestic wastewater in rural areas. However, the sustainable operation of constructed wetland treatment systems depends upon a high rate conversion of organic and nitrogenous loading into their metabolic gaseous end products, such as N2O and CH4. In this study, we examined and compared the performance of three typical types of constructed wetlands: Free Water Surface (FWS), Subsurface Flow (SF) and Vertical Flow (VF) wetlands. Pollutant removal efficiency and N2O and CH4 emissions were assessed as measures of performance. We found that the pollutant removal rates and gas emissions measured in the wetlands exhibited clear seasonal changes, and these changes were closely associated with plant growth. VF wetlands exhibited stable removal of organic pollutants and NH3-N throughout the experiment regardless of season and showed great potential for CH4 adsorption. SF wetlands showed preferable T-N removal performance and a lower risk of greenhouse gas emissions than FWS wetlands. Soil oxidation reduction potential (ORP) analysis revealed that water flow structure and plant growth influenced constructed wetland oxygen transfer, and these variations resulted in seasonal changes of ORP distribution inside wetlands that were accompanied by fluctuations in pollutant removal and greenhouse gas emissions.     

A typical meteorological day (TMD) approach for predicting the long-term performance of solar energy systems

A method for predicting the long-term performance of solar energy systems, based on the analysis of system performance for one particular day—the typical meteorological day (TMD)—is presented. The TMD is constructed from the cumulative time distribution of insolation values on the collector aperture. The TMD method requires little calculational effort and a small data base relative to standard yearly computer simulations. Good agreement is found between the predictions of the new method and the corresponding results of the -f-chart method. The TMD method is of particular value for cases that may often be treated inaccurately by simple calculational methods: (1) high threshold problems; (2) systems with short response times (e.g., due to small storage); and (3) systems in which collectors other than flat plates are used (the method is applicable to all solar collector types).     

Eigen filter to detect volitional EMG signals in autogenic EMG-controlled FES

Presented is an eigen filter to remove autogenic electrical stimulation artefacts and M-waves while preserving the volitional electromyographic signal. The optimality of the eigen filter is shown, along with simulated and measured data to indicate its superior performance over conventional prediction error filters.     

Orientation in uniaxially stretched plasticized atactic polystyrene

Summary Fourier transform infrared spectroscopy and birefringence measurements have been used to study the changes in molecular orientation which occur on drawing of plasticized as compared to pure polystyrene (PS) at a temperature T=Tg+Cte. No influence of plasticizers on orientation can be detected whatever the interactions between small molecules and PS chains are. Comparison with previous results obtained on PS-poly(vinylmethyl ether) compatible blends confirms the importance of the macromolecular nature of the second component to enhance the friction coefficient leading to higher level of chain orientation.     

锗酸铋（Bi4Ge3O12）单晶热物理性质的研究

本文用不同的测试技术和方法测定了锗酸铋(BGO)单晶的比热(300～800K)热膨胀系数(100～1100K)和导温系数(140～700K),进而导出了 BGO 单晶不同温度下的导热系数、定容比热、德拜温度和格虑内森数。本文还对 BGO 单晶热物理性质的变化规律作了理论解释。     

High-speed, polyimide-based semi-insulating planar buried heterostructures

We describe planar buried heterostructure lasers which have low capacitance (lpF), large bandwidth (19GHz), high power (>20mW/facet) and high temperature operation (100°C). These lasers are very suitable for long-distance, highspeed digital and analogue signal transmission.     

Woodceramics Prepared from Wood Powder/Phenolated Wood Composite

In this paper, composites were made from wood powder and its phenolated product, and then were carbonized into woodceramics. The effects of the content of the phenolated wood in the composites on the forming ability, size, density, compressive strength, volume electrical resistivity, and specific surface area of the woodceramics were investigated. It is suggested that in the preparation of woodceramics, phenolic resin can possibly be substituted totally by phenolated wood that is the main constituent of liquefied wood.     

Integrated optical devices of InGaAsP/InP heterojunction phototransistor and inner stripe light-emitting diode

New integrated optical devices combining an InGaAsP/InP HPT and an inner-stripe LED are proposed and their fabrication processes are described. The device functions of light amplification, optical bistability, and optical switching are demonstrated in the 1-μm wavelength region.     

Effect of puffer volume and operating force on dielectric recovery performance in thermal puffer-type gas circuit breaker

In order to investigate the influence of puffer volume V/sub P/ and operating force to dielectric performance of GCB at current interruption, we calculated the prospective dielectric withstand voltage V/sub W/ between arcing contacts. The withstand voltage was calculated by the electric field strength appeared on arcing contacts and the allowable electric field strength E/sub W//sup */ of hot gas due to thermal puffer action. We could clarify that large initial puffer volume V/sub P/ can increase withstand voltage V/sub W/ at current breaking point and also that an optimum point exists in operating force F. For example, it was found that in case of the operating force of 1000 kgf, the puffer volume V/sub P/ of 1.2 liter would be best choice in the interrupting condition of i=50 kA and arcing time of 1.35 cycle.