Thermal error characteristic analysis and modeling for machine tools due to time-varying environmental temperature

The accuracy of machine tools is affected by both internal heat sources and time-varying environmental temperature. Therefore, the thermal deformation caused by environmental temperature variation is an important factor, which requires attention during thermal error modeling. In order to analyze the influence of time-varying environmental temperature on the thermal error of the machine tool, this paper proposed a thermal error modeling approach by using the thermal error transfer function of the machine tool. The approach was implemented in the following three steps. First, the thermal time constant of major components was calculated, according to structural parameters. Then, the thermal error transfer function of the components was derived. Finally, the thermal error transfer function of the whole machine was built based on the construction relationship. The analytical approaches of time domain and frequency domain were applied to obtain the thermal characteristics of machine tools based on the thermal error transfer function. Numerical simulations and the Z-axis operating experiment of three-axis milling machine were performed to verify the accuracy and effectiveness of the thermal error predicted model. The result shows that the proposed model is versatile and general with a clear modeling mechanism, which would provide a useful tool for the analysis and optimization design of machine tools with good thermal robustness.     

浅析电解铝企业的环境污染问题及治理措施

近年来,我国电解铝行业持续快速发展,由此造成的环境压力也十分突出。该文从电解铝生产系统出发,对电解铝企业产生的环境污染问题进行了阐述,并结合当下铝行业发展水平分析了电解铝企业环境污染治理措施。     

略论环境分析

环境分析是保护环境的基础,也是当代分析化学的一大热点,目前尚存在不少难题,本文论述了当前国际上研究的新动向并举例说明若干环境分析的新成果。     

丁苯橡胶充填用环保芳烃油的研制

利用扬子公司范围内的重质物料进行了原料的筛选,提出一种生产环保芳烃油的新型工艺路线,并对环保芳烃油进行了分析及充填橡胶评价。结果表明,与进口典型环保芳烃油相比,生产的环保芳烃油具有密度、黏度、折光偏低的特点,充填橡胶的性能完全达到了指标要求。新型的环保芳烃油完全可替代丁苯橡胶原有非环保高芳填充油。     

Thermoeconomic design of a multi-effect evaporation mechanical vapor compression (MEE–MVC) desalination process

Desalination of seawater accounts for a worldwide water production of 24.5 million m³/day. A “hot spot” of intense desalination activity has always been the Arabian Gulf, but other regional centers of activity emerge and become more prominent, such as the Mediterranean Sea and the Red Sea, or the coastal waters of California, China and Australia. Despite the many benefits the technology has to offer, concerns rise over potential negative impacts on the environment. Key issues are the concentrate and chemical discharges to the marine environment, the emissions of air pollutants and the energy demand of the processes. To safeguard a sustainable use of desalination technology, the impacts of each major desalination project should be investigated and mitigated by means of a project- and location-specific environmental impact assessment (EIA) study, while the benefits and impacts of different water supply options should be balanced on the scale of regional management plans. In this context, our paper intends to present an overview on present seawater desalination capacities by region, a synopsis of the key environmental concerns of desalination, including ways of mitigating the impacts of desalination on the environment, and of avoiding some of the dangers of the environment to desalination.     

Investigation on Cracking Characteristics of Fine-Grained Soils Under Varied Environmental Conditions

Several theories and models that define cracking characteristics of fine-grained soils have been proposed by earlier researchers. However, it has been realized that cracking characteristics of these soils are mainly influenced by the environmental conditions to which they are exposed and on their mineralogical composition. To demonstrate this, investigations were conducted on soils of entirely different characteristics and their cracking characteristics, under varied environmental conditions, resorting to “image analysis.” Based on the study, it has been observed that the cracking characteristics of fine-grained soils, defined as a function of evaporation rate, depend on the soil type (i.e., its mineralogy), environmental conditions, and the thickness of the specimen.     

Sintering and characterization of flyash-based mullite with MgO addition

Mullite ceramics were fabricated at relatively low sintering temperatures (1500-1550 °C) from recycled flyash and bauxite with MgO addition as raw materials. The densification behavior was investigated as function of magnesia content and sintering temperature. The results of thermal analysis, bulk density and pore structure indicate that MgO addition effectively promoted sintering, especially above 1450 °C. Due to the presence of large interlocked elongated mullite crystals above 1450 °C, associated with enhanced densification, an improvement in mechanical strength was obtained for the samples containing magnesia. The addition of magnesia slightly decreases the LTEC at 1300 °C due to the formation of low-expansion α-cordierite, but slightly increases the LTEC above 1400 °C due to the formation of high expansion corundum and MgAl₂O₄ spinel.     

溶剂型氯丁胶粘剂的环保化

论述了环保型胶粘剂的基本特点，分析了溶剂型氯丁胶粘剂的毒性与污染来源，提出了溶剂型氯丁胶粘剂环保化的途径，介绍了环保型氯丁胶粘剂的配制原则，指出了溶剂型氯丁胶粘剂的惟一生路是环保化。     

用后耐火材料的再生利用

综述了国内外对用后耐火材料再利用的情况及其发展趋势。同时介绍了宝钢的有关情况 ,特别是报导了对用后耐火材料的再利用研究成果。再生产品的性能可以接近或达到新产品的水平 ,有些甚至能达到优质耐火材料的水平。