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排序方式: 共有1419条查询结果,搜索用时 46 毫秒
941.
本文在应用两次算法的基础上,应用复合形优化方法,在微机上实现了小功率汽轮机锥形套装叶轮优化设计。与文献6比较,优化后叶轮质量减轻近25%。 相似文献
942.
We propose a behavior-based macro-model of mixed ADC systems as a tool for high-level simulation, investigation and pilot testing, as well as a tool to facilitate and support a design process of other systems containing them. Our aim is to characterize the dynamic and nonlinear properties of ADC systems simultaneously with the representing of discrete nature of ADC output. To introduce the model, we assume that nonlinear and dynamic properties of the system can be separated. Decomposition of the nonlinear static characteristic is performed to calculate the output signal for any sinusoidal input signal. To deal with dynamics, traditional coefficients of the differential equation input-output are used. The discrete nature of ADC system is taken into account by an ideal quatizator, operating at the output of the model. As a result, behavior of the system can be described with a small set of parameters, and each of them can be estimated experimentally. The simulation results confirmed the usefulness of the model. 相似文献
943.
D.H. Kim Y.D. Park Y. Jang H. Yang Y.H. Kim J.I. Han D.G. Moon S. Park T. Chang C. Chang M. Joo C.Y. Ryu K. Cho 《Advanced functional materials》2005,15(1):77-82
With the aim of enhancing the field‐effect mobility by promoting surface‐mediated two‐dimensional molecular ordering in self‐aligned regioregular poly(3‐hexylthiophene) (P3HT) we have controlled the intermolecular interaction at the interface between P3HT and the insulator substrate by using self‐assembled monolayers (SAMs) functionalized with various groups (–NH2, –OH, and –CH3). We have found that, depending on the properties of the substrate surface, the P3HT nanocrystals adopt two different orientations—parallel and perpendicular to the insulator substrate—which have field‐effect mobilities that differ by more than a factor of 4, and that are as high as 0.28 cm2 V–1 s–1. This surprising increase in field‐effect mobility arises in particular for the perpendicular orientation of the nanocrystals with respect to the insulator substrate. Further, the perpendicular orientation of P3HT nanocrystals can be explained by the following factors: the unshared electron pairs of the SAM end groups, the π–H interactions between the thienyl‐backbone bearing π‐systems and the H (hydrogen) atoms of the SAM end groups, and interdigitation between the alkyl chains of P3HT and the alkyl chains of the SAMs. 相似文献
944.
预应力筋──锚具组装件锚固性能的静载试验方法 总被引:4,自引:0,他引:4
近几年来,笔者结合科研和生产需要,通过对钢丝、钢铰线及其镦头锚具、JMF锚具和钢质锥形锚具等不同预应力筋张拉锚固体系进行了大量预应力筋-锚具组装件的静载锚固性能试验,在量测仪器和试验方法上进行了专门研究和改进,对影响锚具锚固性能的各有关参数全部采用自动量测系统进行实测,获得了较好的实验结果,为制定国家标准和实际生产应用提供了大量可靠数据。 相似文献
945.
聚合物刷子的合成及应用 总被引:1,自引:0,他引:1
概述了聚合物刷子的最新进展情况,并着重介绍了固定于固体基体表面的线型聚合物刷子。讨论了聚合物刷子的结构特征;聚合物刷子的合成途径,包括物理吸附法和将聚合物分子以化学键结合到基体表面上的方法,后者又可分为“接枝到表面”和“从表面接枝”两种技术.最后简略地介绍了聚合物刷子的特性及应用。 相似文献
946.
947.
Harry Perros 《Computer Communications》1982,5(2):73-78
The HDLC protocol has proven to be unsuitable for satellite communications where the propagation delay is very large. The paper describes a modification of the HDLC protocol, based on the virtual subchannel concept, that is more suitable for satellite communications. The satellite link is organized into several sub-channels, each operating under the standard HDLC protocol. The performance of this modified protocil is examined, using simulation techniques. 相似文献
948.
949.
950.
Jonathan P. Bramble Daniel J. Tate Derek J. Revill Khizar H. Sheikh James R. Henderson Feng Liu Xiangbing Zeng Goran Ungar Richard J. Bushby Stephen D. Evans 《Advanced functional materials》2010,20(6):914-920
A novel method of creating planar aligned columnar discotic liquid crystals (cDLCs) on surfaces, which also gives control over the azimuthal angle, is presented. Surfaces are chemically patterned with stripes via microcontact printing of organothiol self‐assembled monolayers (SAMs) on gold, or via deep UV patterning of organosilane SAMs on silicon. These are then used to isolate long droplets of cDLCs by dewetting in the isotropic phase. Upon cooling from the isotropic into the hexagonal columnar phase, polarizing microscopy reveals that the cDLC aligns in a planar orientation. Results for three triphenylene derivatives (HAT‐6, HHTT, H7T) and for a phthalocyanine derivative (8H2Pc) are presented. H7T and HAT‐6 are found to align with the director perpendicular to the stripe direction, but HHTT and 8H2Pc align parallel to the stripe direction. This relatively simple new method for creating planar aligned columnar phases of DLCs gives control over the azimuthal angle: a condition required for organic field‐effect transistor applications of cDLCs. 相似文献