级进模结构CAD中装配模型的研究

本文认为模具结构设计是一个面向模具整体功能的装配设计过程.公式化描述了级进模结构特点,在分析并总结了现有“装配模型”的基础上,提出了一个支持级进模结构设计特点的“装配模型”.     

环境行政管理:集中抑或分散

随着我国环境保护形势的变化 ,环境行政管理体制已对其缺乏适应性 ,并存在诸多问题 ,应进行环境行政管理模式的改革。为此 ,笔者联系世界各国的管理模式进行了分析和探讨 ,认为在横向管理权力地相对集中 ,纵向管理权力地相对分散的同时 ,建立各部门、各地区之间的协调机构的管理模式将是一种理性的选择。     

导体表面雷电脉冲电流分布研究

为研究雷电脉冲电流在导体表面的分布情况,研制了巨磁阻(Giant Magneto Resisti ve,GMR)表面电流测量系统,利用该系统对平面薄铝板表面脉冲电流密度进行了测量研究。为验证测量结果,采用时域有限差分(FDTD)法和CST软件分别进行了相应的数值分析和仿真计算,取得与测量相一致的结果。在此基础上,对雷电流在弧面表面分布情况进行了探索性研究。     

云南省丽江大地震及其诱发的崩塌滑坡灾害特征

１９９６年２月３日，云南省丽江县城以北４０ｋｍ发生７级强烈地震，这次地震在约１２０００ｋｍ２范围内诱发了至少４２０处中小型崩塌和３０处大中型滑坡，造成房屋倒塌、桥梁毁坏和公路堵塞。调查研究得出以下结论：（１）地震触发的崩塌滑坡分布在Ⅵ度区内，主要集中在主震震中东南部，接近表层构造断裂带和余震活动范围内；（２）崩塌主要发生在高陡斜坡的峡谷地带，滑坡多为复活型，部分为同发型和滞后型滑坡；（３）地形是控制崩塌滑坡分布位置的主导因素，崩塌多发生于大于６０度斜坡中上部，滑坡发育于中缓斜坡（２５°～４５°）；（４）滑坡影响区如遇充足的降雨可能进一步变形破坏，大量地裂隙孕育着新的崩塌滑坡，潜在危险性大。     

污水厂二级出水中抗生素抗性细菌的紫外灭活与复活特性

抗生素抗性细菌(ARB)作为新兴污染物受到了广泛关注,但紫外线(UV)消毒对ARB去除效果的研究尚不够充分。以某城市污水处理厂过滤后的二级出水为研究对象,通过分析UV消毒前后水中四环素、氨苄西林、氯霉素及链霉素抗性细菌丰度的变化,探究了UV消毒对ARB的去除作用及ARB的光复活与暗修复潜能。结果表明:UV对过滤后二级出水中的4种ARB具有一定灭活能力,4种ARB对UV消毒的耐受能力由高到低分别为:氨苄西林抗性细菌>四环素抗性细菌>链霉素抗性细菌≈氯霉素抗性细菌。当UV消毒剂量为20 mJ/cm2时,氯霉素与链霉素抗性细菌可被完全灭活,消毒后24 h内,这2种ARB未出现光复活或暗修复现象,这一剂量的UV不能完全灭活氨苄西林与四环素抗性细菌,且被灭活后的ARB可实现部分光复活及暗修复。当UV消毒剂量达到80 mJ/cm2时,这4种ARB均被全部灭活,消毒后6 h内,氨苄西林抗性细菌出现了复活现象。不论是在光照还是避光的条件下,UV消毒24 h后水中的总异养菌群中有超过70.32%的细菌对氨苄西林具有抗性,因此,单独UV消毒并不能有效地控制ARB从污水处理厂向环境中的传播。     

Biofilm response and removal via the coupling of visible-light-driven photocatalysis and biodegradation in an environment of sulfamethoxazole and Cr(VI)

The widespread contamination of water systems with antibiotics and heavy metals has gained much attention. Intimately coupled visible -light-responsive photocatalysis and biodegradation (ICPB) provides a novel approach for removing such mixed pollutants. In ICPB, the photocatalysis products are biodegraded by a protected biofilm, leading to the mineralization of refractory organics. In the present study, the ICPB approach exhibited excellent photocatalytic activity and biodegradation, providing up to ∼1.27 times the degradation rate of sulfamethoxazole (SMX) and 1.16 times the Cr(VI) reduction rate of visible-light-induced photocatalysis . Three-dimensional fluorescence analysis demonstrated the synergistic ICPB effects of photocatalysis and biodegradation for removing SMX and reducing Cr(VI). In addition, the toxicity of the SMX intermediates and Cr(VI) in the ICPB process significantly decreased. The use of MoS₂/CoS₂ photocatalyst accelerated the separation of electrons and holes, with•O₂^– and h⁺ attacking SMX and e^– reducing Cr(VI), providing an effective means for enhancing the removal and mineralization of these mixed pollutants via the ICPB technique. The microbial community results demonstrate that bacteria that are conducive to pollutant removal are were enriched by the acclimation and ICPB operation processes, thus significantly improving the performance of the ICPB system.     

固化/稳定化修复后场地中铬的环境行为和归趋:以我国中部某修复后场地为例

为了探讨铬(Cr)在固化/稳定化修复后场地中的环境行为与归趋,通过浸出环境评价框架(LEAF)浸出评价、形态分级以及微观表征,对我国中部某修复后场地土壤中Cr的含量及形态进行3轮次跟踪监测. 结果表明:①跟踪监测试验发现,该修复后场地土壤中总Cr含量下降了18.92%. 在芥菜植株中Cr分布存在差异,其中,芥菜叶中Cr含量高达1.62 mg/kg (以干质量计),芥菜茎中Cr含量为0.69~0.77 mg/kg (以干质量计). 芥菜植株吸收Cr的能力为0.44~3.10 mg/m2,对土壤中总Cr减量化的贡献率最高仅为0.05%;另外,新鲜芥菜植株中Cr含量为0.12~0.69 mg/kg,超过GB 2762—2017《食品安全国家标准 食品中污染物限量》中规定限值(0.5 mg/kg),一旦食用该场地中的芥菜会对人体健康产生影响,增加了Cr在修复后场地中风险暴露的途径. ②土壤微观表征试验表明,修复后场地土壤中Cr主要以Cr₂O₃形式存在,土壤中的Mn_xO_y能起到氧化Cr的作用. 在LEAF试验中,固化/稳定化的Cr被活化溶出;而BCR分析发现,Cr的可还原态占比随修复后时间的延长逐渐增加,由1.13%增至4.02%. ③土壤中Mn、Fe及植物等环境因子均会参与Cr的氧化还原、沉淀与溶解,以及植物吸收与富集等环境行为,并导致已被固化/稳定化的Cr溶解或再氧化成Cr(Ⅵ)而溶出,从而增加Cr的迁移性和毒性,造成环境风险,其中Mn(Ⅳ)是Cr活化的关键因子. 研究显示,修复后场地中Cr的环境行为会受到多种环境因素共同影响,尤其是在Mn含量较高的区域更易形成氧化氛围导致Cr的重新活化.      

Enhanced degradation of reactive brilliant red X-3B by photocatalysis integrated with micro-electrolysis

Environmental Science and Pollution Research - The microwave electrodeless lamp UV photocatalysis (MWUV) integrated with iron carbon micro-electrolysis (ME) was applied to degrade reactive...     

Polyols and Rigid Polyurethane Foams from Cashew Nut Shell Liquid

Cashew nut shell liquid (CNSL) is a natural aromatic oil consisting of a mixture of phenolic structures with a carboxyl group in ortho position and substituted in meta position with a hydrocarbon chain of 15 carbon atoms. The major component of CNSL is anacardic acid (90?%), which is easily decarboxylated to cardanol by distillation. The present work describes the synthesis of new biobased Mannich polyols for rigid polyurethane foams in two steps: synthesis of Mannich bases by reacting phenolic ring of cardanol with N-(2-hydroxyethyl)-1,3-oxazolidine followed by alkoxylation reactions. The polyols were characterized by wet methods (hydroxyl numbers, viscosity, acid value, density, water content, iodine value etc.), spectroscopic methods (FT-IR, ¹H NMR and ¹³C NMR) and by Gel Permeation Chromatography. The Mannich polyols from cardanol are excellent replacements for petrochemical derived Mannich polyols based on nonyl phenol. Cardanol-based polyols were used successfully for the preparation of rigid polyurethane foams of good physical?Cmechanical and fireproofing properties.     

车载式接地装置的相关试验研究及时域分析

为了研究车载接地问题，研制了可迅速安装和撤收的便携式接地模块。以多个接地模块组成十字型和一字型组合接地装置，模块之间用多芯铜绞线相连。利用接地实验系统对组合接地装置进行试验，同时对实验系统建模，采用时域有限差分法进行数值分析。通过对一字型和十字型接地装置进行实验研究及数值分析，得出两种组合接地装置的优劣。