基于生态径流指标的水文情势变化评估新方法

基于流量历时曲线计算生态径流指标的方法存在诸多不足,也未形成相应的河流水文情势变化评估方法。采用流量过程线重新定义了月、季和年三种时间尺度的生态径流,构建了包含12个月生态盈余和12个月生态赤字的生态径流指标体系,提出了衡量这些指标在建库前后变化度的计算公式,基于月生态赤字发展了月生态风险评估方法,形成了一种河流生态水文情势变化评估方法。将其用于长江宜昌站,评估三峡工程在建库前后的生态水文情势变化。结果表明：重新定义的月、季、年生态径流之间消除了不一致性,香农多样性指数与年生态赤字的年际变化具有更高的相似度,变化度计算公式完全适用于衡量建库前后的变化程度,生态风险图使生态径流指标的实用性大为增强。     

Dressing of filigree fine-grained metal bonded grinding wheels

Metal bonded grinding tools offer a remarkable potential for micro grinding because of their favorable wear behavior. However, metal bonded grinding tools, especially dicing blades, are hard to dress by conventional dressing methods. Electro contact discharge dressing, which is presented in this paper, is a numerically controlled dressing process offering the possibility to create the geometry and topography of the grinding wheel simultaneously at negligible dressing forces. The power of an electric circuit thermally removes the metal bond of the grinding wheel during the dressing process. The quality of the created profiles and the influence of the dressing parameters on the specific material removal rate of the grinding tool as well as the wear of the electrode are investigated at fine-grained grinding wheels.     

氮气和熔剂联合净化铝熔体

研究了SDJ 1型熔剂与氮气联合净化铝合金熔体的效果 ,并对熔剂净化机理以及FI法 (Fluxinjection)净化优势进行了探讨 ,揭示了除气过程中气体与熔剂的相互作用。结果表明 :采用FI联合精炼工艺 ,在适当的温度 (72 0℃ )和熔剂加入量 (0 .15 %SDJ 1)条件下 ,联合精炼工艺的除气效果远远优于生产中常用的氮气吹气法和熔剂法 ,联合净化法的优势在于提高了吸附能力以及加入具有固氢作用的降渣剂。FI工艺原理为 :气体与熔剂在熔体中均匀分布、密切接触 ,气体使熔剂快速上浮 ,熔剂的存在提供多而窄的通道 ,使氢容易聚集在通道附近 ,即使氢含量较低时 ,氮气仍能发挥作用 ,通道的存在有利于分散和离解气泡。     

Mn含量对Mg2Ni型合金相形成及放电性能的影响

采用按比例混合合金粉末压制成圆柱试样，然后用低温烧结和随后机械球磨的方法制备了非晶态的Mg2Ni型合金。研究了烧结和球磨对不同Mn含量的Mg2Ni型合金的相形成过程及电化学性能的影响。实验表明：在Mg2Ni中采用第三组元Mn对Mg进行适量的替代后，通过烧结及球磨方法可以获得均匀的非晶相；微量替代可有效地提高其放电容量：随替代量的增加，合金最大放电容量和高速放电能力降低，而充放电循环稳定性提高。     

Study On the Tribological Behavior of the Arc-added Glow Discharge Plasma Non-hydrogen Carburization On Titanium Alloy Surfaces

This paper introduces a new titanium alloys surface strengthening treatment by using the arc-added glow discharge plasmas non-hydrogen carburization technique. High purity and high strength graphite is selected as cooling cathode arc source for supplying carbon atoms and particle, which migrate to the titanium alloy(Ti6Al4V) surface and form modified layer. Thus, the hydrogen embrittlement is avoided while the tfibological behavior of the titanium alloy surface is improved in the respects of anti-friction and anti-wear ability.The tribological behavior of the modified layer under dry sliding against SAE52100 steel was evaluated on a ball-on-disc test rig. The results showed that the modified layer obtained a thickness of 30μm at 980℃, 30minutes. The microhardness of the Ti6Al4V alloy surface attained 936 HV, which was much larger than that of the Ti6AI4V alloy. The Ti6AI4V alloy was characterized by adhesion wear and scuffing under dry sliding against the steel, while the surface modified layer experienced much abated adhesion wear and scuffing under the same testing condition. This could be attributed to the carbon dement with different modalities exists in the modified layer.The modified layer showed good friction-reducing and fair anti-wear ability in dry sliding against the steel. Using the SEM,XRD and XPS, the phase structure and morphology of the carburization modified layer was analyzed.     

An investigation of ultrasonic-assisted electrical discharge machining in gas

This study focuses on using ultrasonic to improve the efficiency in electrical discharge machining (EDM) in gas medium. The new method is referred to as ultrasonic-assisted electrical discharge machining (UEDM). In the process of UEDM in gas, the tool electrode is a thin-walled pipe, the high-pressure gas medium is applied from inside, and the ultrasonic actuation is applied onto the workpiece. In our experiment, the workpiece material is AISI 1045 steel and the electrode material is copper. The experiment results indicate that (a) the Material Removal Rate (MRR) is increased with respect to the increase of the open voltage, the pulse duration, the amplitude of ultrasonic actuation, the discharge current, and the decrease of the wall thickness of electrode pipe; and (b) the surface roughness is increased with respect to the increase of the open voltage, the pulse duration, and the discharge current. Based on experimental results, a theoretical model to estimate the MRR and the surface roughness is developed.     

40Cr钢电火花表面强化层的磨损特性研究

分析了在大接触应力的磨损条件下,表面残余应力和硬度对40Cr电火花强化层耐磨性的影响,探讨了其磨损机理。结果表明:滚动磨损和滚、滑动磨损时,随着试样表层硬度的提高,试样的耐磨性增大;强化层中的残余压应力可以提高强化层的硬度并增强其耐磨性。滚动磨损时,电火花强化层的磨损方式主要为粘着磨损、疲劳磨损和磨粒磨损三种机制;在滚、滑动磨损时,除上述三种机制外,还发生了氧化磨损。     

环氧氯丙烷下游产品生产现状及市场前景

论述了环氧氯丙烷的主要下游产品环氧树脂、合成甘油、氯醇橡胶等的生产现状、市场前景等,指出:我国氯碱行业应该重视这些环氧氯丙烷下游精细化工产品的开发,以促进我国环氧氯丙烷的发展。     

国内化纤市场的现状及预测

分析了１９９３年底至１９９４年１季度国内化纤价格上扬及１９９５年２季度以来价格下滑的形势，提出国内化纤工业调整的必要，并预测了今后国内化纤市场的发展趋势。     

两性聚丙烯酰胺的合成方法及应用进展

结合国内外研究情况，从技术路线和实施方法两个角度着重阐述了制备两性聚丙烯酰胺的方法，同时简单介绍了其应用情况，并对今后的研究工作提出了一些建议。