Leishmaniosis--a report about the microvascular and cellular architecture of the infected spleen in Canis familiaris

Leishmaniosis is an anthropozoonosis caused by an intracellular protozoan parasite that causes a wide spectrum of diseases in humans and dogs worldwide. In the Mediterranean basin, Portugal, Central and South America, and in the Middle East, visceral leishmaniosis is caused by Leishmania infantum. In these areas, dogs are believed to be the natural reservoirs of this parasite. In the case of visceral leishmaniosis, the spleen is one of the several hematopoietic and immunocompetent organs involved. Since this viscera is a blood filter, the authors investigated the expression of the morphological and microvascular environment and modifications of the spleen cell population related to immunological responses to this parasitic condition. The tools used to perform this study were scanning electronic microscopy of intact tissue and corrosion casts, transmission electronic microscopy, histology and immunohistochemistry. The results reveal three important modifications concerning the spleen's microvascular architecture when compared with its normal pattern, independently of the serological titer obtained with indirect immunofluorescence. (1) A marked scarcity of the sinusoidal system sheet that surrounds the central artery/arteriole of the white pulp; (2) A huge development of pulp venules and veins; (3) The presence of a surprising development of reticular fibers. The authors postulate that independent of the virulence of the parasite involved and the type of immunity prevalent in a particular host, the spleen develops blood dynamic conditions that permit reduction in the speed of blood flow so that cells involved in immunological processes can proliferate and differentiate, and also contributes to trapping lymphocytes within the area through the differentiation of characteristics that resemble those of HEV endothelial cells.     

管道机器人适应不同管径的三种调节机构的比较

为了使管道机器人能够适应管径为400～650mm的管道,介绍了3种适应不同管径的常用调节机构.分析了每种调节机构的力学特性,给出了计算结果,比较研究了各种调节机构的优缺点.针对工程需要,选用了滚珠丝杠螺母副调节机构,滚珠丝杠上的筒式压力传感器保证驱动轮和管道内壁间的压力始终处于稳定的范围,使管道机器人具有充裕并且稳定的牵引力,牵引力的实验表明该调节机构具有1404N的牵引力输出.该调节机构能很好地适应管径为400～650mm的管道.     

Mesopic state: cellular mechanisms involved in pre- and post-synaptic mixing of rod and cone signals

At least twice daily our retinas move between a light adapted, cone-dominated (photopic) state and a dark-adapted, color-blind and highly light-sensitive rod-dominated (scotopic) state. In between is a rather ill-defined transitional state called the mesopic state in which retinal circuits express both rod and cone signals. The mesopic state is characterized by its dynamic and fluid nature: the rod and cone signals flowing through retinal networks are continually changing. Consequently, in the mesopic state the retinal output to the brain contained in the firing patterns of the ganglion cells consists of information derived from both rod and cone signals. Morphology, physiology, and psychophysics all contributed to an understanding that the two systems are not independent but interact extensively via both pooling and mutual inhibition. This review lays down a rationale for such rod-cone interactions in the vertebrate retinas. It suggests that the important functional role of rod-cone interactions is that they shorten the duration of the mesopic state. As a result, the retina is maintained in either in the (rod-dominated) high sensitivity photon counting mode or in the second mode, which emphasizes temporal transients and spatial resolution (the cone-dominated photopic state). Experimental evidence for pre- and postsynaptic mixing of rod and cone signals in the retina of the clawed frog, Xenopus, is shown together with the preeminent neuromodulatory role of both light and dopamine in controlling interactions between rod and cone signals. Dopamine is shown to be both necessary and sufficient to mediate light adaptation in the amphibian retina.     

Semi-analytical derivation of approximate non-linear eigenvalues and eigenvectors for general non-linear MDOF systems

This work introduces a novel theoretical formulation for the evaluation of approximate eigenvalues and eigenvectors for general non-linear MDOF systems using the so-called “approximate non-linear mode evaluation” (ANME) method. The approach is based on analytically derived quasi-linear expressions which relate the change in modal parameters to physical non-linear elements that can be added anywhere in the system. Subject to assuming that the change in the mode shape is small, expressions for non-linear eigenvalues and eigenvectors become fully determined for a general MDOF system, even within typical experimental constraints. The errors arising from this assumption can be minimized via an iterative procedure. Preliminary results indicate that the rate of convergence is quite fast for systems with medium to high damping but more effort is required for lightly damped systems. The derived expressions provide a theoretical basis for observations made by previous researchers from an inspection of their experimental and/or numerical results: these indicate that an invariant relationship exists between a non-linear eigenvalue and its associated modal response.     

Spectral analysis for non-linear systems, Part II: Interpretation of non-linear frequency response functions

In Part I of this series new methods of parametric spectral analysis for a wide class of non-linear systems were introduced. In this, the second part, the interpretation and properties of the non-linear frequency response functions are discussed and illustrated by example.     

Frequency response of non-linear single degree-of-freedom systems

Simple linear Kelvin or Maxwell models cannot predict adequately the response of many practical systems to vibration excitation. A more realistic model consisting of a mass between two preloaded non-linear (cubic elasticity springs) and restrained by a Coulomb and viscous damper is proposed. A harmonic motion solution, satisfying “on the average” the non-linear differential equation of motion of the model is developed whereby equations for frequency response curves are obtained. Expressions for relative and absolute transmissibility as well as their values at resonance are developed, these are shown to properly reduce to the respective exact expressions of a Kelvin model and friction damped linear spring. Although the model is intended mainly for quantitative design in packaging engineering problems, it is suitable for studying general vibration isolation problems as well.     

Experimental study of non-linear effects of photomultiplier gain

The experimental apparatus and the results of a study on the gain variation of photomultipliers at high average anode current are described. This gain variation was found to depend on the secondary emission process on dynodes; the last dynode gives the largest contribution to the overall photomultiplier effect. This contribution has been isolated and measured. The phenomenon may be due to more than one physical effect. The dominant one turns out to depend on the power released on the dynode by the incident electrons. A physical model is discussed which can take into account the observed phenomena.     

机组非线性模型的多变量内模控制

大型火力发电机组的协调控制系统是一个复杂的多变量非线性控制系统。随着科学技术和生产的迅速发展,对复杂和不确定性系统实行自动控制的要求不断提高,为进一步改善控制品质,必须采用先进控制器。内模控制由于具有良好的跟踪性能和抗干扰能力,并对模型失配有一定的鲁棒性,使其在工业控制中获得了广泛的应用。为了克服非线性环节以及能量供需之间关联耦合作用对协调系统控制品质的影响,本文结合反馈线性化方法与多变量内模控制,对机组非线性模型设计出非线性内模控制器。     

Dynamic restoring and dissipative parameters of non-linear systems

Elastometer vibration and shock absorbing machinery mountings and package cushioning cannot be accurately modeled as linear Voigt type systems, since most of them exhibit stiffening or softening elasticity in conjunction with friction and viscous damping. Improved accuracy may be achieved by a non-linear shock or vibration loaded model, incorporating linear with non-linear elasticity and combined Coulomb and viscous damping. Formulae of such a model are compiled whereby optimal cushioning systems and mounts in shock and vibration loading may be designed. The use of these formulae requires experimental evaluation of two pairs of restoring and dissipative parameters in shock and vibration loading. Equations and test procedures for evaluating these parameters by means of shock and vibration machine tests are presented, along with a detailed discussion of properties of hysteresis loops of non-linear single degree of freedom systems in shock and vibration loading. A special test jig is described comprising a non-linear system with adjustable non-linear elasticity as well as variable Coulomb and viscous damping. This jig was used to evaluate the validity of the mathematical model by means of extensive tests on a shock and vibration machine. Programs developed for an Apple II microcomputer facilitated rapid and accurate computations whereby a numerical example is presented as an illustration of the procedure for evaluating restoring and dissipative parameters. This mathematical model and test procedures are believed to closely approximate shock and vibration isolation systems. As such, they may be conducive to developing better cushioning material and improved machinery mounts.     

Analysis of orthotropic bearing non-linearity using non-linear FRFs

Among other critical conditions in rotor systems the large non-linear vibration excited by bearing non-linearity causes the rotor failure. For reducing this catastrophic failure and predictive detection of this phenomenon the analysis of orthotropic bearing non-linearity in rotor system using higher order frequency response functions (HFRFs) is conducted and is shown to be theoretically feasible as that of non-rotating structures. The complex HFRFs based on the Volterra series are newly developed for the process and investigated their features by using the simple forms of the FRFs associated with the forward and the backward modes.     

The geometrically non-linear analysis of transversely loaded membranes

This paper deals with flat membranes which are subjected to transverse loading and which undergo large deflections. A method is proposed based on the framework analogy and examples are given to demonstrate the effectiveness of the approach.     

液力变矩器非线性特性的研究

在建立液力变矩器的模型基础上,根据能量守恒进行分析、并推导出液力变矩器的等效粘性阻尼系数公式。再通过液力变矩器原始特性对其等效阻尼系数进行拟合计算．得出了液力变矩器非线性等效阻尼系数与涡轮、泵轮速比及泵轮转速的定量关系。同时通过变矩器的力学分析,推导出液力变矩器的假设的等效刚度与速比和泵轮转速的定量非线性关系。     

数字传感器非线性校正方法研究

针对数字型传感器-石英晶体温度传感器的非线性校正设计了几种方法,通过实验分析了这几种方法的优缺点和可行性。结果证明,综合传感器的特性、精度要求、软件实现的复杂程度等几方面因素,同时采用两种或两种以上方法,能够达到理想校正效果。     

Surface plasmon-assisted widefield non-linear imaging of gold structures

In this paper, we demonstrate how the confinement and enhancement of optical fields by surface plasmon resonance can allow non‐linear microscopy to be performed in a simple, cost‐effective widefield configuration, rather than the more usual laser‐scanning arrangement. We present second harmonic and two‐photon luminescence widefield images of dielectric and gold samples obtained with both prism‐based and high numerical aperture objective (‘prismless’) microscope arrangements.     

起重机交流调速系统特点

介绍了近年来起重机常用电气交流调速系统的基本工作原理、主要性能和特点 ,为起重机生产厂家生产或用户订购起重机或类似设备时选配适用的控制系统提供参考。     

起重机系统的建模及其非线性间断的反馈控制

推导了桥式起重机系统的非线性动态模型。模型在无外力的情况下，具有2个输入和4个自由度。控制模型的目标是建立使小车和滑轮组尽快到达预定位置，并消除钢丝绳和负载由惯性所致摆角的控制方案。并将模型和控制方案在MATLAB模拟软件里进行测试，验证其测试结果与理论分析的一致性。     

一类不确定非线性系统的自适应滑模控制

滑模变结构控制系统能够通过控制其本身结构的变化,使得系统性能保持一直高于一般固定结构控制所能达到的性能,突破了经典线性控制系统的品质限制,适用于非线性的不确定系统。同时滑模控制能保证在模型的不确定和外部扰动的情况下系统的稳定性与鲁棒性,而且以损失能导致抖振的最优控制性能而得到稳定鲁棒性,同时它的不确定性上界必须是已知的,但有时候很难得到上界。这样提出一种自适应的方法以进一步避免这些问题,同时这种方法能保证闭环系统的稳定性。本论文给出仿真结果来验证该方法的有效性。     

起重机非线性摇摆系统的仿真和分析

本文将MATLAB和SIMULINK仿真工具相结合应用在起重机非线性摇摆系统的建模和仿真上,发挥了MATLAB计算功能强大和SIMULINK仿真简便直观的优点,提出了通过控制小车加(减)速时间的方法并进行了仿真,结果表明对于抑制吊重摇摆是十分有效的。     

Practical limits of resolution in confocal and non-linear microscopy

Calculated and measured resolution figures are presented for confocal microscopes with different pinhole sizes and for nonlinear (2-photon and second harmonic) microscopes. A modest degree of super-resolution is predicted for a confocal microscope but in practice this is not achievable and confocal fluorescence gives little resolution improvement over widefield. However, practical non-linear microscopes do approach their theoretical resolution and therefore show no resolution disadvantage relative to confocal microscopes in spite of the longer excitation wavelength.     

Fast reduced model of non-linear dynamic Euler-Bernoulli beam behaviour

This paper introduces a new way to obtain the dynamical response of Euler-Bernoulli beams under large deflections. They are simulated with parsimonious models based on a two integrated neural networks. Our article proves that neural network based-reduced modelling allows mechanical simulations to benefit shorter time processing without a great loss of accuracy. Our model reduction technique ensures a good error-speed compromise. It rapidly leads to algebraic generic model matching interactive simulation or high-realistic multi-sensorial virtual protoyping requirements. The originality of our solution consists in the linking of two neural networks. They are integrated in a conditional loop. First, the article presents a systematic numerical technique that enables users to efficiently build an optimal neural network. This approach is based on the handling of discrete optimization evolutionary technique. Our optimization process is applied to the construction of the two neural networks. From an exhaustive learning base created from non-linear finite element analysis series, we secondly clearly describe our two neural network-based reduced models. The first neural network that enables nodal displacements to be determined from boundary conditions is linked to the second one that aims to set boundary conditions from a deformation state. The new relationship is finally analysed for justifying the successes of our proposal. The article completely details a new numerical process supervising the making of an integrated neural network loop being a new from of model for beam non-linear behaviour representation.