基于H∞//μ鲁棒控制原来和使用ATMD的高楼主动振动控制策略研究

对使用主动脉调频质量块ＡＴＭＤ（ＡｃｉｔｖｅＴｕｎｅｄＭａｓｓＤａｍｐｅｒ）的具有ｎ阶自由度的柔性大楼结构建立了全阶模型,并由此将得到的结构降价模型用于设计ＡＴＭＤ的控制器,通过分析,大楼结构的位置和速度可被列为控制器的输出反馈变量,将等效两端口模型应用于带ＡＴＭＤ的大楼结构上,使用Ｈ∞／μ频域定型综合理论,设计出ＡＴＭＤ的鲁棒控制器,通过模拟分析,可见该控制算法是非常有效的,ＡＴＭＤ中的小质量决     

Cognitive Factors in Programming with Diagrams

Visual programming languages aim to broaden the use ofdiagrams within the software industry, to the extentthat they are integrated into the programming languageitself. As a result, they provide an ideal opportunityto study the benefits of diagrams as an externalrepresentation during problem solving: not only isprogramming a challenging problem-solving activity,but the effect of diagram usage can be directlyassessed by comparing performance while using a visualprogramming language to performance with a standardtextual language. There have been severalmisconceptions amongst visual language researchersregarding the role of diagrams in software design, butthese are being addressed by empirical studies and bynew theories of notation design derived from studiesof visual programming. Based on this research, theauthors are able to recommend several new directionsfor research into thinking with diagrams.     

A computational model for tracking subsurface tissue deformation during stereotactic neurosurgery

Recent advances in the field of stereotactic neurosurgery have made it possible to coregister preoperative computed tomography (CT) and magnetic resonance (MR) images with instrument locations in the operating field. However, accounting for intraoperative movement of brain tissue remains a challenging problem. While intraoperative CT and MR scanners record concurrent tissue motion, there is motivation to develop methodologies which would be significantly lower in cost and more widely available. The approach we present is a computational model of brain tissue deformation that could be used in conjunction with a limited amount of concurrently obtained operative data to estimate subsurface tissue motion. Specifically, we report on the initial development of a finite element model of brain tissue adapted from consolidation theory. Validations of the computational mathematics in two and three dimensions are shown with errors of 1%-2% for the discretizations used. Experience with the computational strategy for estimating surgically induced brain tissue motion in vivo is also presented. While the predicted tissue displacements differ from measured values by about 15%, they suggest that exploiting a physics-based computational framework for updating preoperative imaging databases during the course of surgery has considerable merit. However, additional model and computational developments are needed before this approach can become a clinical reality.     

Three distinct D-amino acid substitutions confer potent antiangiogenic activity on an inactive peptide derived from a thrombospondin-1 type 1 repeat

Mal II, a 19-residue peptide derived from the second type 1 properdin-like repeat of the antiangiogenic protein thrombospondin-1 (TSP-1), was inactive in angiogenesis assays. Yet the substitution of any one of three L-amino acids by their D-enantiomers conferred on this peptide a potent antiangiogenic activity approaching that of the intact 450-kDa TSP-1. Substituted peptides inhibited the migration of capillary endothelial cells with an ED50 of 8.5 nM for the D-Ile-15 substitution, 10 nM for the D-Ser-4 substitution, and 0.75 nM for the D-Ser-5 substitution. A peptide with D-Ile at position 15 could be shortened to its last seven amino acids with little loss in activity. Like whole TSP-1, the Mal II D-Ile derivative inhibited a broad range of angiogenic inducers, was selective for endothelial cells, and required CD36 receptor binding for activity. A variety of end modifications further improved peptide potency. An ethylamide-capped heptapeptide was also active systemically in that when injected i.p. it rendered mice unable to mount a corneal angiogenic response, suggesting the potential usefulness of such peptides as antiangiogenic therapeutics.     

The Hobetron-a high power vacuum electronic switch

This paper describes a new high-power, hollow electron beam, current-regulating switch tube that we call the Hobetron. Experimental data on the Litton L-6026 Hobetron, an engineering prototype designed to stand off 125 kV dc and switch 200 amps, has demonstrated that Hobetron performance is in excellent agreement with computer predictions over the range of test. Further, the data confirmed that L-6026 switch power loss is less than 20% that of standard magnetron injection gun (MIG) switch tubes (for similar currents through each). Various potential Hobetron applications are presented throughout the paper. It is possible to include an additional electrode in the basic Hobetron configuration for even higher voltage standoff and switch current capability, and the paper presents an arrangement capable of standing off 500 kV dc and switching 500 amps. Simulations of a superpower “Hobetron-Plus” are presented, and the potential of this device as an efficient, 50 MW peak, relatively compact, VHF power amplifier for advanced heavy-particle (e.g., muon) colliders, is evaluated