摩擦换向抽油机悬点运动分析计算

摩擦换向抽油机采用开关磁阻电动机或变频调速电动机,其特点是可以频繁双向旋转,带动摩擦轮正反转,实现光杆的上行下行。该抽油机运动特点与游梁式抽油机运动特点有较大区别,文章分析了摩擦换向抽油机的运动特点,给出了该机悬点位移、速度、加速度的计算方法。     

Bioeffects of Low Energy Ion-Beam Implantation and Vacuum Treatment on M1 Arabidopsis Thaliana

Vacuum treatment and ion-beam bombardment are two major processes in the low energy ion-beam implantation. To accurately study the contributions of these two major factors to the bioeffects separately, the M1 generation variation of Arabidopsis thaliana with ion-beam implantation and vacuum treatment were compared through a series of key plant development parameters including morphological observation, biochemical assay and RAPD （random amplified polymorphic DNA） analysis. The results showed that ion-beam implantation had obvious effect on almost all of these parameters, and the vacuum treatment had some impacts on several morphological parameters such as the bolting time and the length of the primary stem. Taking the results together, the indication is that vacuum treatment has some slight contributions to the bioeffects of ion-beam implantation while ion-beam bombardment itself is the major creator of the bioeffects.     

Low-temperature growth of silicon-boron layer as solid diffusionsource for polysilicon contacted p+-n shallow junction

A new material, Si-B, is proposed as a solid diffusion source for fabrication of poly-Si contacted p⁺-n shallow junctions. The junction depth of the Si-B source diode has been measured and compared with that of a BF₂⁺-implanted poly-Si source diode. It was found that the Si-B source diode had a much shallower junction and was less sensitive to thermal budget than the BF₂⁺ source diode. This was attributed to the smaller surface concentration and diffusivity of boron in the silicon in Si-B source diodes. Regarding electrical characteristics of diodes with a junction depth over 500 Å, a forward ideality factor of better than 1.01 over 8 decades and a reverse-current density lower than 0.5 nA/cm² at -5 V were obtained. As the junction depth shrank to 300 Å, the ideality factor and reverse current density of diodes increased slightly to 1.05 and 1.16 nA/cm², respectively. These results demonstrated that a uniform ultrashallow p⁺-n junction can be obtained by using a thin Si-B layer as a diffusion source     

Quadtree based colour quantisation image compression

A new colour quantisation and quadtree based image compression scheme is proposed. The features of the new scheme are that colour palette ordering and requantisation of the decoded image for palette-based monitor displays are not required. Thus, fast decoding and displaying can be achieved     

Performance Evaluation of Range Queries in Key Value Stores

Recently there has been a considerable increase in the number of different Key-Value stores, for supporting data storage and applications on the cloud environment. While all these solutions try to offer highly available and scalable services on the cloud, they are significantly different with each other in terms of the architecture and types of the applications, they try to support. Considering three widely-used such systems: Cassandra, HBase and Voldemort; in this paper we compare them in terms of their support for different types of query workloads. We are mainly focused on the range queries. Unlike HBase and Cassandra that have built-in support for range queries, Voldemort does not support this type of queries via its available API. For this matter, practical techniques are presented on top of Voldemort to support range queries. Our performance evaluation is based on mixed query workloads, in the sense that they contain a combination of short and long range queries, beside other types of typical queries on key-value stores such as lookup and update. We show that there are trade-offs in the performance of the selected system and scheme, and the types of the query workloads that can be processed efficiently.