PMI-St-AN耐热改性剂的合成及应用

以提高聚氯乙烯(PVC)的耐热性能为目的,用悬浮聚合的方法,合成了N-苯基马来酰亚胺-苯乙烯-丙烯腈三元共聚物型耐热改性剂。通过差热分析、元素分析、凝胶渗透色谱分析等手段对共聚物的玻璃化转变温度、组成及其分布、分子量及其分布进行了表征。初步考察了丙烯腈的加入对N-苯基马来酰亚胺-苯乙烯交替共聚体系共聚合规律的影响。将合成的耐热改性剂用于PVC共混改性,取得了较好的效果。     

Transient and turbulent mass transfer in rotating shallow electrochemical cells

Turbulent mass transfer in a rotating shallow electrochemical cell was investigated experimentally. Six local miniprobes embedded in the cathode were used to measure the local mass transfer rate and to detect unsteady turbulent convection. The mass transfer rates were nondimensionalized and correlated. A critical parameter was obtained to describe the onset of transient and turbulent conditions in the rotating electrochemical cells. The transient and turbulent phenomena in the rotating system are more complex than natural convection in vertical enclosures because of gravity-gradient effects.     

浅议水厂处理工艺改进和新工艺的研究

本文介绍了近年来我公司水厂在净水工艺方面的改进，以及在新工艺、新设备方面所做的研究。     

Design,fabrication and performance analysis of a 200 W PEM fuel cell short stack

A PEM fuel cell short stack of 200 W capacity, with an active area of 100 cm² has been designed and fabricated in-house. The status of unit cell performance was 0.55 W cm⁻². Based on the unit cell technology, a short stack has been developed. The proper design of uniform flow distribution, cooling plate and compressed end plate were important to achieve the best performance of the short stack. The performance of four cells stack was analyzed in static and dynamic modes. In the static mode of polarization curve, the stack has peak power density of 0.55 W cm⁻² (220 W) at 0.5 V per cell, when the voltage was scanning from low to high voltage (1.5–3.5 V), and resulted in minimum water flooding inside the stack. In this study a series of dynamic loadings were tested to simulate the vehicle acceleration. The fuel cell performances respond to dynamic loading influenced by the hydrogen/air stoichiometric, back pressure, and dynamic-loading time. It was needed high hydrogen stoichiometric and back pressure to maintain high dynamic performance. In the long-time stable power testing, the stack was difficult to maintain at high performance, due to the water flooding at high output power. An adjusting cathode back-pressure method for purging water was proposed to prevent the water flooding at flow channels and maintain the stable output power at 170 W (0.42 W cm⁻²).     

Effect of clamping pressure on the performance of a PEM fuel cell

Examined were the effects of the clamping pressure on the performance of a proton exchange membrane (PEM) fuel cell. The electro-physical properties of the gas diffusion layer (GDL) such as porosity, gas permeability, electrical resistance and thickness were measured using a special-designed test rig under various clamping pressure levels. Correlations for the gas permeability of the GDL were developed in terms of the clamping pressure. In addition, the contact resistance between the GDL and the bipolar (graphite) plate was measured under various clamping pressures. Results showed that at the low clamping pressure levels (e.g. <5 bar) increasing the clamping pressure reduces the interfacial resistance between the bipolar plate and the GDL that enhances the electrochemical performance of a PEM fuel cell. In contrast, at the high clamping pressure levels (e.g. >10 bar), increasing the clamping pressure not only reduces the above Ohmic resistance but also narrows down the diffusion path for mass transfer from gas channels to the catalyst layers. Comprising the above two effects did not promote the power density too much but reduce the mass-transfer limitation for high current density.     

简析酱油新老标准之异同

对比酱油新老标准,新标准包括一个酿造酱油标准和一个配制酱油标准,增加了对原辅料、铵盐、标签等内容的强制性条款,新标准科学、合理,易于宣传贯彻执行。     

盖下坝水电站坝址区岩溶发育情况初步分析

盖下坝水电站工程为高山峡谷型电站,坝址区及附近岩石为碳酸盐岩,属中等坚硬易溶岩.岩溶发育是影响本工程库水外渗的重大工程地质问题之一.从施工开挖揭示的各种溶蚀现象中分析岩溶发育特征及其规律,为防渗设计提供依据.     

Numerical investigation of different loads effect on the performance of planar electrode supported SOFC with syngas as fuel

Reducing greenhouse gas emission such as carbon dioxide is the goal of each country. As a developing country with coal as the dominant energy source, China confronts the pressure of saving energy and reducing emission by using coal efficiently and cleanly. Integrated gasification fuel cell (IGFC) hybrid power generation system is one of optimal system for clean coal utilization. In this work, the three-dimensional mathematical models for planar solid oxide fuel cell (SOFC) with syngas as fuel was constructed, and its performance was numerically investigated at different loads. Under all calculating conditions, the optimal power density is obtained at current density of 4700 A m⁻², where the output voltage is 0.57 V and the power density is 2671.01 W m⁻². With the increasing of current density, the temperature increase as well. And also the difference of max- and min-temperature in SOFC enhances. But the ohmic over-potential changes unobvious. Furthermore, the change rate of species is nearly linear with the increment of current density.     

TiO2/CdS composite hollow spheres with controlled synthesis of platinum on the internal wall for the efficient hydrogen evolution

Solar driven semiconductor photocatalytic water splitting to produce hydrogen is an extremely charming process by storing photon energy in chemical bonds. In the present study, composite semiconductor TiO₂/CdS was structured into uniform and porous double-shelled hollow sphere with cocatalyst platinum selectively loaded onto the internal wall. The SEM, TEM, STEM, XRD, BET and EDS elemental distribution etc. were employed to evidence the formation of the targeted photocatalyst. It was demonstrated that the material has a high efficiency of visible-light-driven hydrogen evolution (296 μmol·h⁻¹/10 mg) with an apparent quantum efficiency (QE) of 14.5% at wavelength of 420 nm. Comparative experiment analysis and time-resolved infrared absorption study suggested that the high photocatalytic activity of the catalyst is attributed to the vectorial electron transfer (CdS → TiO₂ → Pt) and the spatial separation of reduction and oxidation active surfaces achieved by the special morphology.     

通信系统浪涌保护器的性能试验及评价分析

浪涌保护器（SPD）的作用是把窜入电力线、信号传输线的瞬时过电压限制在设备或系统所能承受的电压范围内,或将强大的雷电流泄流入地,使被保护的设备或系统不受冲击而导致损坏.对于通信系统来说,其过电压保护与电气设备相比,有不同的技术要求.依据GB/T 18802.22-2008电信和信号网络的电涌保护器选择和使用导则,对通信系统所用电涌保护器进行了试验,并结合样品测试分析结果,在对照国标要求进行解读的基础上,提出对信号SPD的性能评价及建议.