我国对二甲苯产能和市场分析

介绍了近十年我国对二甲苯的生产和消费情况,对2014年对二甲苯产能和市场进行了统计分析,并对我国对二甲苯行业的未来发展进行了展望。     

Thermal shock behavior of co-continuous TiCx-Cu cermets in air and anaerobic environment

The present work investigated the microstructure and mechanical properties of TiC_x-Cu cermets before and after thermal shock tests. Thermal shock temperature was from 800 °C to 1200 °C and number of cycles was from 1 to 20. The results indicated that TiC_x-Cu cermets with co-continuous structure exhibited a stable and excellent thermal shock resistance. When quenched at 1000 °C for 1 cycle, the residual flexural strength of the cermet increased to 882 MPa, which was 10.1% higher than that without thermal shock. After 20 cycles of thermal shock, the residual flexural strength still maintain 760 MPa. When quenched at 800 °C and 1200 °C, the strengths of cermet decreased correspondingly, which were caused by the thermal mismatch between metal and ceramics and effusion of Cu or collapses of oxide layer, respectively. Herein, the recrystallization and refinement of metal phase grains caused during the thermal shock process, resulting in the superior thermal shock performance of cermet.     

Mechanical properties of in situ synthesized mullite-based composite ceramics with three-dimensional network structure

Needle-like nanocrystalline mullite powders were prepared through the molten salt process at the temperature of 900°C using coal gangue as raw material. Then, mullite-based composite ceramics were prepared by a conventional solid-state reaction between in situ synthesized mullite and Al₂O₃ powders. Effects of Al₂O₃ content and sintering temperatures on phase compositions, microstructure, and mechanical properties of the mullite-based composite ceramics were also studied. The results show that mullite content productivity increase from 72% to 95%, as the sintering temperature increased from 1480°C to 1580°C, which led to the improvement in the bulk density and flexural strength of the samples. The three-dimensional interlocking structure for mullite-based composite ceramics was obtained by the in situ solid-state reaction process. The maximum bulk density, flexural strength, and fracture toughness for the sample with 15 wt% Al₂O₃ content are 2.48 g/cm³, 139.79 MPa, and 5.62 MPa··m^1/2, respectively, as it was sintered at the temperature of 1560°C for 3 h. The improved mechanical properties of mullite-based composite ceramics maybe ascribed to good densification and increased mullite phase content, as well as to the in situ three-dimensional network structure. Therefore, the results would provide new ideas for high-value utilization of coal gangue.     

应用图解法对含有微量强酸的弱酸的线性滴定

用图解法和一元线性回归法,对含有微量强酸的不同类型的弱酸进行了多组线性滴定,得到了满意的分析结果。为使用常规的测试手段,简单的一元线性数学处理,提供了一个简便可行的实验方法。     

地开石的特性及其在铸造涂料中应用的研究

用现代测试手段较深入地分析了安徽地开石的矿物特性及有关物理性质,确定了合适的热处理工艺。通过试验,拟定了地开石涂料的配方,测定了涂料的工艺性能,并对浇注后的涂料烧结层进行微观分析。研究结果表明,地开石涂料是一种烧结剥离型涂料,具有较强的抗粘砂能力。     

聚苯胺-二氧化锡纳米复合材料合成及表征

用溶胶-凝胶法制备了平均粒径为25m的金红石结构的SnO2微粒,采用原位聚合工艺制备了聚苯胺-二氧化锡(PANI-SnO2)复合材料.利用XRD、FT-IR和TEM对产物进行了表征.结果表明,复合材料两相间存在化学键合作用;无机纳米相影响了聚苯胺结晶,使其由部分结晶态转变为无定形态;复合后部分聚苯胺红外吸收峰发生移动,这是由于聚苯胺内氮原子孤对电子和苯醌结构中的π电子向Sn原子空轨道转移造成的.微观结构表征显示,复合材料呈"蛋糕-巧克力"结构,高分子基体一定程度上减少了纳米微粒的团聚,改善了其分散性.     

ICP-MS法同时测定青海省柴北缘某地区多金属矿石中的钨锡

钨、锡传统的分析方法采用过氧化钠熔融-比色法分别进行测定,具有成本高、效率低等问题。根据青海省柴北缘某地区多金属矿石样品的特性,采用过氧化钠熔融,盐酸酸化,电感耦合等离子体质谱法同时测定多金属矿石中的钨和锡。该方法测定结果的相对标准偏差为1.17%~7.15%,经标准物质验证准确度良好,且与传统分析方法测定结果吻合。该方法节省了样品处理和分析时间,提高了工作效率,节约了分析测试成本,适用于大批量样品的分析测试。     

OpenMP‐oriented applications for distributed shared memory architectures

The rapid rise of OpenMP as the preferred parallel programming paradigm for small‐to‐medium scale parallelism could slow unless OpenMP can show capabilities for becoming the model‐of‐choice for large scale high‐performance parallel computing in the coming decade. The main stumbling block for the adaptation of OpenMP to distributed shared memory (DSM) machines, which are based on architectures like cc‐NUMA, stems from the lack of capabilities for data placement among processors and threads for achieving data locality. The absence of such a mechanism causes remote memory accesses and inefficient cache memory use, both of which lead to poor performance. This paper presents a simple software programming approach called copy‐inside–copy‐back (CC) that exploits the data privatization mechanism of OpenMP for data placement and replacement. This technique enables one to distribute data manually without taking away control and flexibility from the programmer and is thus an alternative to the automat and implicit approaches. Moreover, the CC approach improves on the OpenMP‐SPMD style of programming that makes the development process of an OpenMP application more structured and simpler. The CC technique was tested and analyzed using the NAS Parallel Benchmarks on SGI Origin 2000 multiprocessor machines. This study shows that OpenMP improves performance of coarse‐grained parallelism, although a fast copy mechanism is essential. Copyright © 2004 John Wiley & Sons, Ltd.     

基于广义后缀树结合过滤因子的正则表达式匹配算法

为了提高正则表达式在文本集合上的匹配效率,提出一种基于广义后缀树与过滤因子相结合的正则表达式匹配技术.根据给定的文本集合构建广义后缀树,通过在广义后缀树上定位过滤因子得到有效的候选匹配集合,利用过滤因子的序列信息进一步过滤候选集合,进而对候选集合中的字符串进行验证,得到匹配结果.通过在真实的数据集上进行实验,证明了该算...     

行波管阴极热子组件结构的热分析

本文分析了不同结构的阴极热子组件与其加热效率的关系.组件的加热效率受阴极支持筒侧面辐射的影响较大,支持筒直径与阴极基底直径相近时,组件加热效率高.并利用ANSYS软件对阴极热子组件进行了热模拟,计算了不同结构组件的温度分布.制备的阴极热子组件的温度试验,结果与计算机仿真在趋势上是一致的,从而为阴极热子组件的设计和优化提供了有力的理论依据和指导.