无卤型电缆用无机耐火隔板 无卤型电缆用无机耐火槽盒

1　前言　　近年来 ,我国电力部门、供电部门和用电量较大的工矿企业 ,因电缆着火延燃酿成火灾时有发生 ,给国民经济带来较大损失。电缆火灾事故无论是由外界火源引起 ,或是自身故障造成 ,都有火势猛、蔓延快、抢救难、损失重大的特点 ,电缆着火原因多样化 ,又难以从根本上避免     

3S技术在日本筑波山梅林公园规划上的应用

以日本筑波山梅林公园规划为例,总结了利用3S技术进行园林规划的方法及其起到的作用,并阐明了如何将得到的经验教训结合我国国情,推动我国相关方面的发展进程.     

Human response to blast-induced vibration and air-overpressure: an Indian scenario

Ground vibration (V_max) and air-overpressure/noise (p) are some of the negative effects of blasting. The associated human annoyance and complaints are expected to show an increasing trend in the future as there is no economically viable alternative to blasting in mines in India.A study of the human response to blasting in four mining localities across India has shown that the response is not simply political, as frequently assumed. It has been found that irrespective of those questioned, a basic concern for the safety of property was the main response. There was a greater response from the middle-aged and middle-educated while fewer women than men responded. Assuming that a 100% negative response from the inhabitants will translate into complaints, a methodology is suggested to take account of the human response criteria when considering blasting within 400 m of habitations.     

Evaluation of the fern Azolla for growth, nitrogen and phosphorus removal from wastewater

Water fern (Azolla filiculoides Lam.) has been assessed for nitrogen and phosphorus removal in outdoor experiments comparing sewage water (S) from an experimental aquaculture plant, well water (W) and mineral growth medium Hoagland (H). The experiments were undertaken during the spring and the summer. The yield of fern biomass and nitrogenase activity was higher in H than in W and S waters. The enzyme activity had a decreasing trend with significant differences (p < 0.05) in the three waters. Peroxidase (POD) activity in April decreased with significative differences in W and S waters (p < 0.05). The electrical conductivity and the concentrations of NO3- in the three waters decreased significantly (p < 0.05). The highest removal of nitrate from the media was obtained in July. In S water, NO2- concentration decreased, while it increased in W water. PO(4)3- concentration was very low in W and S waters and decreased in H medium. The results obtained confirm the ability of the fern to grow in sewage water.     

Enhanced sound absorption properties of porous ceramics modified by graphene oxide films

Under the condition of constant thickness, improving the low-frequency sound absorption performance of conventional sound-absorbing materials is a challenging research topic. To address this issue, a new reduced graphene oxide/polyvinyl alcohol (RGO/PVA) porous composite ceramic was fabricated using freeze-drying and optimized by redesigning the internal connecting pores of porous ceramic matrixes with a reticular microstructure using RGO and PVA. The as-prepared porous structure showed significant enhancement in the low-frequency sound absorption band compared with pristine porous ceramics. In addition, the hybrid porous ceramics exhibited low thermal conductivity. These favorable properties indicate that the hybrid sound-absorbing ceramics have potential application prospects for noise reduction in the fields of construction and electrical and mechanical devices.     

Machining of NiTi-shape memory alloys-A review

The emerging trends in the development of advanced smart materials with better unique properties under different environments for a particular application fascinate the researchers and industrialists. Nickel-Titanium based shape memory alloys are exotic materials due to their unique properties such as SME, SE, high damping characteristics, high corrosion and wear resistance and biocompatibility. This article presents an overview of machining processes that can be used to machine the NiTi and its surface induced characteristics such as microhardness, surface roughness, topography, induced layer, residual stress, fatigue and phase transformation. The surface integrity characteristics are discussed for machining of NiTi-SMAs under the category of traditional, non-traditional and micro-machining with the effect of input parameters such as cutting speed, feed, depth of cut, type of lubricant and type of coating material on cutting tool. The conventional machining of NiTi alloys are quite complicated due to high toughness, severe strain hardening, fatigue hardening and distinctive property of NiTi-SMAs such as pseudoelastic and shape memory effect. From this study, non-traditional process is significantly used to machine the NiTi-SMAs due to its better results on surface integrity characteristics. Consequently, future trends are also identified for machining the NiTi-SMAs and to improve the surface integrity characteristics.     

3D Monte Carlo simulation of grain growth in friction stir welding

Journal of Mechanical Science and Technology - The 3D fluid model was used to simulate the friction stir welding process. Three-dimensional Monte Carlo model with nucleation in each MC step was...     

上海四平大楼爆破拆除中环境振动监测的分析

介绍上海四平大楼组合楼宇定向爆破拆除时对周边环境的振动监测,通过环境的振动监测准确地了解楼宇倾倒触地时监测控制点的振动速度值,从而有效地评估组合楼宇被爆破拆除时对相邻环境的影响状态.通过对集录的测试数据分析可以递推估算周边相邻建筑的影响状况,也可为以后类同爆破环境作前期的评判指导作用.应该肯定随着大体积建筑物爆破拆除工程的发展,对爆破中环境振动监测的要求将越来越强烈.