Methane activation without using oxidants over Mo/HZSM-5 zeolite catalysts

The effect of Mo loading, calcination temperature, reaction temperature and space velocity on the catalytic performance of methane dehydrogenation and aromatization without using oxidants over Mo/HZSM-5 has been studied. The XRD and BET measurements show that Mo species are highly dispersed in the channels of the HZSM-5 zeolite, resulting from the interaction between the Mo species and the zeolite, which also leads to a decrease in its crystallinity. The Brønsted acidity, the channel structure and the state and location of Mo species in the zeolite seem to be crucial factors for its catalytic performance. It was found that 2% Mo/HZSM-5 calcined at 773 K showed the best aromatization activity among the tested catalysts, the methane conversion being 9% at 1013 K with the selectivity to aromatics higher than 90%. The experimental results obtained from the variation of space velocity gave evidence that ethylene is an initial product. On the basis of these results a possible mechanism for methane dehydrogenation and aromatization has been proposed in which both the heterolytic splitting of methane in a solid acid environment and a molybdenum carbene-like complex as an intermediate are of significance.     

CONFIGURATION OF AN ADVANCED INDUSTRIAL CONTROL HIERARCHY FOR COPPER MANUFACTURE

The proposed hierarchical arrangement of the copper plant control is presented.The hierar-chical control in copper manufacture and the recent computer advances in this area are dis-cussed.It is also described how a hierarchical computer network can provide a means for effec-tive integrated central control in this article.     

ZigBee技术的汽车胎压监测系统设计

针对目前直接主动式汽车胎压监测系统处理器与射频芯片分开设计、433 MHz无线频率造成的系统体积大、无组网、抗干扰能力弱等关键技术问题,设计了一种基于无线传感器网络的直接主动式汽车胎压监测系统.其中系统采用ZigBee首款SOC单芯片CC2430,无线通信频率为2.4 GHz.软件设计上改进了ZigBee通讯协议CSMA/CA机制,这样既能有效避免各轮胎监测节点发送数据的冲突,又能降低系统能耗、延长网络寿命.该系统能够实时自动监测轮胎内部压力、温度等状态信息,从而有效地保障了汽车行驶安全.     

神经网络对φ-有界变差函数的逼近

研究了以有界的sigmoidal函数σ为激活函数的单隐层神经网络对于在[a,b]上φ-有界变差函数f的逼近,得到的逼近偏差为‖σ‖φ-1{Vφ(fn)[a,b]/n}.倘若激活函数是Heaviside函数时,则逼近偏差为φ-1{Vφ(f)[a,b]/2n}.此外,在第3节中,我们还将上述结果扩充到了全实轴上.     

基于BP网络的驾驶员昼间动态空间距离判识

为研究昼间动态环境中驾驶员对空间距离判识规律,进行了实际道路试验.统计32名驾驶员分别在昼间不同深度距离、速度下,红色障碍物空间距离判识结果,获得判识特征值.运用BP神经网络,模拟距离判识结果,分析距离判识变化规律.结果表明:在同一深度距离下,绝对距离和相对距离判识结果均随速度增加而减小,相对距离判识准确性高.BP网络...     

钢液预处理→120t转炉→钢包精炼→真空脱气→连铸流程生产GCr15轴承钢的纯净度

对7炉采用钢液预处理→120t转炉→钢包精炼→真空脱气→连铸流程生产的GCr15轴承钢进行了氧、氮及残余元素含量分析、非金属夹杂物评级、夹杂物电子探针观察和能谱分析以及电解夹杂物等分析。结果表明:采用该流程生产的GCr15轴承钢的纯净度较高,尤其是氮元素含量和残余元素含量均比电炉流程生产的GCr15轴承钢明显降低;钢中的夹杂物主要是铝酸钙和氧化铝,也有少量的硫化物和氮化物,而且总是以复合夹杂物的形式存在。     

计算机关键技术在烟草机械协同并行研发设计中的应用

以中国烟草机械集团有限责任公司及控股企业异地协同并行研发设计平台系统(以下简称协同平台)为例,阐述了计算机及网络的复制、虚拟交换、负载均衡、网闸、CA认证等有关技术在异地协同并行研发设计中的应用.重点介绍PDM系统中的远程数据复制技术、交换机设备的虚拟交换架构,并以应用服务器的负载均衡为例论证了负载均衡技术,从网络、数...     

Rare earth organic complexes as down-shifters to improve Si-based solar cell efficiency

This work reports on the optical and electrical characterization of crystalline silicon based solar modules encapsulated with ethylene-vinyl-acetate layers (that is the encapsulating matrix used nowadays by the photovoltaic industry) doped with a single europium complex whose sensitized region is broadened due to the presence of a co-ligand. Such europium doped EVA layers are able to realize down-shifting of photons with wavelength lower than 460 nm without introducing modifications of the industrial process leading to the fabrication of the photovoltaic modules. This effect has been proven under Air Mass 1.5 conditions (simulating terrestrial applications), where a 2.9% relative increase of the total power delivered by the encapsulated modules has been observed, allowing a reduction in the watt-peak price.     

船舶铁舾件工时定额估算方法研究

为了解决人工工时估算不准确且费时等问题,准确测算船舶铁舾件舾装作业的工时定额,提出了基于CBR和BP神经网络的铁舾件装配工时定额制定方法.针对铁舾件细分工种安装工艺相似但型号各异的特点,提出基于非数值型和数值型特征参数相结合的相似性规律,在已知部分型号舾装工时情况下,利用相似性检索方法找出与新铁舾件最相似的铁舾件集,根...