文留油田抽油井偏磨腐蚀综合治理

从机理研究入手，对文留油田抽油井偏磨、腐蚀形成的多种因素进行了系统分析，并采取了一系列针对性措施，有效地减缓了偏磨、腐蚀对抽油井的破坏，延长了检泵周期。     

Dual update-rate carrier tracking technique for new generation global navigation satellite system signals in dynamic environments

With the upcoming of modernised Global Positioning System (GPS) and Galileo, the new generation global navigation satellite systems (GNSSs) will be able to provide the users a better positioning performance. An important modification on most of the new generation GNSS signal structures is the availability of the pilot channel, which stands for an additional measurement obtained; moreover, a pure phase-locked loop (PLL) can be used in carrier-phase tracking loop. Utilising this characteristic, the authors present a dual update-rate PLL for modernised GNSS signals to deal with the well-known dilemma that the usage of long coherent integral time can help in reducing the noise from thermal effects, whereas the usage of short coherent integral time can permit the tracking loop to suffer more dynamics stress. By processing data and pilot channels with different coherent integral times, different discriminators, and then performing the fusion of those two different update-rate measurements in a Kalman-filter-based loop filter, this loop offers several advantages over the traditional methods in dynamic and low carrier-to-noise ratio (CNR) environments. Simulation results demonstrate that the proposed dual update-rate PLL shows good performance in both dynamic and low CNR environments.     

SiC MESFET反向截止漏电流的研究

给出了一种减小SiC MESFET栅漏反向截止漏电流的工艺方法,通过采用LPCVD淀积厚SiO2和高温氧化工艺,使器件的性能得到一定的提升.从实验数据看出,器件在S波段工作时,器件的反向截止漏电流大幅度下降,且分散性得到改善,其功率附加效率和功率增益也分别提高了10%和1.5 dB.该方法充分发挥了SiC材料能形成自身氧化层的优势,结合Si工艺的特点,减小了氧化层的缺陷,并在一定程度上减小了器件的寄生电容.     

日神精神与酒神精神——闲话建筑理性与本性的表达

<正>生活在Delft,古老的中世纪教堂、幽静的荷兰式住区,房门外自由戏水的野鸭……荷兰的城市没有西班牙的美艳,却多着几许弥漫着烤面包香味的生活气息。终于有一天,这种心灵和视觉上的恬淡被一座看似"巨型心脏"的城市雕塑惊碎。D-tower,荷兰杜廷赫姆市交互感应式     

哈希链在IPTV数字版权管理中的应用

DRM系统是IPTV中关键的一环。本文采用基于PKI的数字证书和公钥加密技术，保证了安全性；通过引入哈希链算法，解决了DRM系统密钥管理中的问题。文章对DRM系统面临的一些问题进行了改善，对实际生产应用具有一定的指导意义。     

蜡油加氢精制-临氢降凝双反应器串联工艺试验

采用加氢精制-临氢降凝双反应器串联工艺,以某炼油厂蜡油为原料生产润滑油基础油。结果表明,主要产品为高黏度的润滑油馏分,其凝点降到-10℃以下,副产少量轻柴油、粗汽油及石油液化气;该工艺具有流程简单、精制降凝效果好、润滑油收率高等特点。     

The energy consumption in a batch stripper and a batch rectifier

The energy consumption in a batch rectifier and a batch stripper was investigated with a shortcut mathematical model. The minimum energy consumption of a batch stripper was compared to that of a batch rectifier under “general constant reflux” and “general constant distillate composition” with the ratio of minimum energy consumption E _S /E _R . When the feed contains a large amount of light component, the product purity specification is low and the relative volatility is small, the minimum energy consumption of a batch stripper is less than that of a batch rectifier under “general constant reflux” and “general constant distillate composition”. When the feed contains a small amount of light component, the product purity specification is very high and the relative volatility is low, a batch stripper can also consume less energy only in the “general constant distillate composition” operation mode. In other cases, a batch rectifier can consume less energy.     

热泵干燥装置中绿色热泵工质的优选

热泵干燥具有节能及物料干燥质量好等优点。传统热泵干燥装置中的热泵工质对大气臭氧层有破坏作用和较大的温室效应 ,在发达国家已被禁用。本文目的在于优选可代替上述环害工质的绿色工质。文中对不同热风温度的热泵干燥装置 ,分别给出了一组可选工质 ,并对各组可选工质进行了分析和评介     

Removal of sulfur compounds from utility pipelined synthetic natural gas using modified activated carbons

Synthetic natural gas (SNG), which is produced from petroleum and distributed via pipeline in Honolulu by The Gas Company, was analyzed using a gas chromatograph equipped with a sulfur chemiluminescence detector (GC/SCD). Hydrogen sulfide (H₂S), methyl mercaptan (MM), ethyl mercaptan (EM), dimethylsulfide (DMS), dimethyl disulfide (DMDS), tetrahydrothiophene (THT), ethyl disulfide (EDS), and one unidentified compound (UN1) were detected. Among these sulfur compounds, THT is added as an odorant and was present in the highest concentration.A commercial activated carbon (Calgon OLC plus 12X30) was modified by oxidation and impregnation methods and the resulting materials were evaluated for their ability to adsorb sulfur compounds present in SNG. The evaluation results indicate that all of the modification methods can improve the retention of individual sulfur compounds or the total sulfur capacity compared with the untreated virgin carbon. It is also found that activated carbons impregnated with metal impurities have different selectivity for sulfur compounds. Cu and Zn loaded carbons had the highest capacity for H₂S removal, Fe loaded carbon was more efficient for DMS removal (the most difficult S compound to remove), and carbon oxidized by HNO₃ was the best for THT removal.Based on these findings, a composite sorbent consisting of Cu loaded and Fe loaded carbons was designed and tested. The test results indicate that the composite sorbent had improved performance in the removal of individual sulfur compound. A linear programming model was used to design a composite sorbent optimized to minimize the required sorbent mass based on a 1-kW scale fuel cell system service target. Validation tests showed that the optimized sorbent required less of the individual modified carbon components than when they were individually used for the same sulfur removal target.     

Accelerating sequence searching: dimensionality reduction method

Similarity search over long sequence dataset becomes increasingly popular in many emerging applications, such as text retrieval, genetic sequences exploring, etc. In this paper, a novel index structure, namely Sequence Embedding Multiset tree (SEM − tree), has been proposed to speed up the searching process over long sequences. The SEM-tree is a multi-level structure where each level represents the sequence data with different compression level of multiset, and the length of multiset increases towards the leaf level which contains original sequences. The multisets, obtained using sequence embedding algorithms, have the desirable property that they do not need to keep the character order in the sequence, i.e. shorter representation, but can reserve the majority of distance information of sequences. Each level of the tree serves to prune the search space more efficiently as the multisets utilize the predicability to finish the searching process beforehand and reduce the computational cost greatly. A set of comprehensive experiments are conducted to evaluate the performance of the SEM-tree, and the experimental results show that the proposed method is much more efficient than existing representative methods.