On classical state space realisability of quadratic input–output differential equations

This article studies the realisability property of continuous-time quadratic input–output (i/o) equations in the classical state space form. Constraints on the parameters of the quadratic i/o model are suggested that lead to realisable models. The complete list of second- and third-order realisable i/o quadratic models is given and two subclasses of the n-th order realisable i/o quadratic systems are suggested. Our conditions rely basically upon the property that certain combinations of coefficients of the i/o equations are zero or not zero. We provide explicit state equations for realisable second-order quadratic i/o equations, and for one realisable subclass of quadratic i/o equations of arbitrary order.     

蠕墨铸铁制动盘体表面黑斑的防止措施

介绍了大功率机车蠕墨铸铁制动盘表面产生黑斑的原因及危害,并分析了黑斑的形成机理,最终通过控制CE、蠕化剂的加入量、孕育剂的加入量、改善浇注工艺、增加涂料的涂刷厚度等措施,使盘体表面黑斑基本消除,蠕化率达到85％,制动盘铸件合格率达到90％以上,大大降低了生产成本.     

Optimal design of elastic-plastic beams with additional supports

An optimization problem of elastic-plastic beams is discussed. An additional support, whose location must be selected so as to minimize the compliance of the beam, is introduced to the beam. The problem is solved with the aid of the optimal control theory. A new optimality condition is presented. Two example problems are solved.     

Optimal design of elastic-plastic stepped beams under dynamic loading

The optimal design of two-stepped elastic-plastic beams under dynamic loads is discussed. Such beam dimensions are sought for which a minimum peak deflection is attained within designs of constant volume. The numerical results achieved are compared with results for elastic and rigid-plastic beams obtained in previous papers by the author.     

A series solution to the nash strategy for large scale interconnected systems

Optimum control of a linear large scale dynamic system is formulated as a game problem using individual subsystem quadratic cost functions and an overall Nash solution strategy. Computational complexities of the exact solution for large systems is overcome by parametric series solution based on ?-coupling. Computational virtues of this approach are noted, and the relation of the approximate and exact solutions is examined.     

Intrinsic and extrinsic mechanisms of vortex formation in superfluid3He-B

We report on the first comprehensive measurements of critical superflow velocities in³He-B which allow different mechanisms of vortex formation to be identified. As a function of temperatureT and pressureP, we measure the critical angular velocity Ω_c(T, P) at which vortices start to form in slowly accelerating rotation in a cylindrical container filled with³He-B. Owing to the long coherence length ξ(T, P)∼10–100 nm, either trapped remanent vorticity or intrinsic nucleation may dominate vortex formation, depending on the roughness of the container wall and the presence of loaded traps. NMR measurement with a resolution of one single vortex line allows us to distinguish between different processes: (1) Three extrinsic mechanisms of vortex formation have been observed. One of them is the vortex mill, a continuous periodic source which is activated in a rough-walled container well below the limit for intrinsic nucleation. (2) In a closed smooth-walled container intrinsic nucleation is the only mechanism available, with a critical velocity v_c(T, P)=Ω_c(T, P), whereR is the radius of the container. We findv _c (T, P) to be related to the calculated intrinsic stability limitv _ch (T, P) of homogeneous superflow. The existence of this connection in the form of a scaling law implies that nucleation takes place at an instability, rather than by thermal activation or quantum tunneling which become impossible because of an inaccessibly high energy barrier.     

NMR signatures of topological objects in rotating superfluid3He-A

NMR spectrometry can be used to identify different topological objects in the order parameter field of rotating superfluid³He-A. We list their signatures in the cw NMR absorption line shape. Quantized vortex lines, domain walls, and their combination, the vortex sheet, all induce satellite peaks with specific intensities and frequency shifts in the NMR spectrum. Examples of spectra are presented to allow a comparison and to distinguish between different objects.     

On optimal design of compressed beams with an additional lateral support

Buckling of axially loaded elastic-plastic beams is discussed. The load is applied instantaneously and remains unaltered during the motion. The effect of stress waves travelling along the beam is taken into account. It is assumed that the material has linear strain-hardening.An additional rigid support is laid to the beam. The location of this support must be determined so that the beam slenderness is maximal at the buckling threshold. It follows from numerical examples that sudden constant loads of infinite duration reduce the critical beam slenderness, but have only a small effect on the optimal location of the support.     

Genome‐wide mapping of cellular traits using yeast

Yeast has long enjoyed superiority as a genetic model because of its short generation time and ease of generating alleles for genetic analysis. However, recent developments of guided nucleases for genome editing in higher eukaryotes, and funding pressures for translational findings, force all model organism communities to reaffirm and rearticulate the advantages of their chosen creature. Here I examine the utility of budding yeast for understanding the genetic basis of cellular traits, using natural variation as well as classical genetic perturbations, and its future prospects compared to undertaking the work in human cell lines. Will yeast remain central, or will it join the likes of phage as an early model that is no longer widely used to answer the pressing questions? Copyright © 2014 John Wiley & Sons, Ltd.     

Automatic calculation for bending of rigid-plastic beams under dynamic loading

Rigid-plastic stepped beams under impulsive or dynamic pressure loading are considered. The ends of the beam are simply supported, clamped or free. Permanent deflections of the beam are found by the method of mode form motions. For automatic calculation of the deflections a FORTRAN packet of programs DINOPT is put together. Three examples which demonstrate the facilities of this packet are given.