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Static Properties (static + property)
Selected AbstractsMachine Tools With Metal Foams,ADVANCED ENGINEERING MATERIALS, Issue 9 2006R. Neugebauer Abstract Machine tool construction calls for subassemblies with reduced weight while retaining excellent dynamic properties. Modern frame components do always meet required static stiffness but often display oscillation problems due to low component wall thicknesses. Breaking down solid steel structure into wide-area sandwich designs such as steel-aluminum foam-steel panels results in good static properties to be combined with excellent properties since these sandwiches have 30 to 40 times the flexural strength. This is due to their major geometrical moment of inertia in relation to adequate-mass steel sheet metals. In addition, the foam core dampens oscillations. Studies on foamed steel sections indicate that 2 to 3 times higher damping is likely in relation to unfoamed steel sections. These benefits were the motivation for the Chemnitz Metal Foam Center to accelerate development of extremely large-format sandwiches with dimensions of 1,500,×,1,000,mm2. [source] Convergence analysis of blind image deconvolution via dispersion minimizationINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2006C. Vural Abstract A new non-linear adaptive filter called blind image deconvolution via dispersion minimization has recently been proposed for restoring noisy blurred images blindly. This is essentially a two-dimensional version of the constant modulus algorithm that is well known in the field of blind equalization. The two-dimensional extension has been shown capable of reconstructing noisy blurred images using partial a priori information about the true image and the point spread function in a variety of situations by means of simulations. This paper analyses the behaviour of the algorithm by investigating the static properties of the cost function and the dynamic convergence of the parameter estimates. The theoretical results are supported with computer simulations. Copyright © 2006 John Wiley & Sons, Ltd. [source] Effects of ultraviolet irradiation on the static and dynamic properties of neoprene rubbersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Hsoung-Wei Chou Abstract Rubbers deteriorate when they are exposed to ultraviolet irradiation for long periods of time. By conducting a series of hardness measurements and simple tension tests, the static properties of neoprene rubbers before and after exposure to various durations of ultraviolet irradiation were first measured. It is found that the Shore A hardness and tensile modulus of neoprene rubbers after exposure to ultraviolet irradiation are increased but their elongation at break, tensile strength, and energy to break are significantly decreased. On the basis of a complex spring model of a vibration system, the dynamic shear properties of neoprene rubbers before and after exposure to different durations of ultraviolet irradiation were then determined from the experimental results of dynamic transmissibility tests. It is also found that the storage modulus, loss modulus, and loss factor of neoprene rubbers are drastically affected by the duration of ultraviolet irradiation they experienced. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Stiffness, viscosity, and upper-limb inertia about the glenohumeral abduction axisJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2000Li-Qun Zhang To evaluate the dynamic properties of the shoulder and understand how they are controlled by the central nervous system, glenohumeral-joint stiffness and viscosity and upper-limb inertia were quantified under various levels of muscle contraction in seven healthy human subjects. Through a cast attachment, the upper limb was perturbed in a precise pattern by a computer-controlled servomotor to manifest the dynamic properties of the joint. The recorded joint position and torque were used to estimate joint stiffness and viscosity and upper-limb inertia. With moderate muscle contraction, the stiffness and viscosity increased several fold. A stiffer shoulder joint associated with stronger muscle contraction made the shoulder more stable and protected it from potential injuries during strenuous tasks. Joint viscosity, especially the stronger viscous damping associated with more strenuous contraction, smoothed shoulder movement and stabilized the joint. From the control viewpoint, the glenohumeral joint responded to the central nervous system more quickly with increasing muscle contraction, which was useful during strenuous tasks. On the other hand, the central nervous system controlled stiffness and viscosity synchronously so that it dealt with only a nearly constant damping ratio of the joint over various levels of contraction, which simplified its task substantially. This approach quantified the dynamic and static properties of the shoulder under various levels of contraction more accurately and completely than a manual test, and it can potentially be used to evaluate changes in these properties caused by musculoskeletal injuries and their surgical treatments. [source] Universal scaling in a trapped Fermi super-fluid in the BCS-unitarity crossoverLASER PHYSICS LETTERS, Issue 12 2009S.K. AdhikariArticle first published online: 14 AUG 200 Abstract Using numerical simulation based on a densityfunctional equation for a trapped Fermi super-fluid valid along the BCS-unitarity crossover, we establish robust scaling over many orders of magnitude in the observables of the system as a function of fermion number. This scaling allows to predict the static properties of the system, such as energy, chemical potential, etc., for a large number of fermions, over the crossover, from the knowledge of those for a small number (,4 , 10) of fermions. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] A review of forecast error covariance statistics in atmospheric variational data assimilation.THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 637 2008II: Modelling the forecast error covariance statistics Abstract This article reviews a range of leading methods to model the background error covariance matrix (the B -matrix) in modern variational data assimilation systems. Owing partly to its very large rank, the B -matrix is impossible to use in an explicit fashion in an operational setting and so methods have been sought to model its important properties in a practical way. Because the B -matrix is such an important component of a data assimilation system, a large effort has been made in recent years to improve its formulation. Operational variational assimilation systems use a form of control variable transform to model B. This transform relates variables that exist in the assimilation's ,control space' to variables in the forecast model's physical space. The mathematical basis on which the control variable transform allows the B-matrix to be modelled is reviewed from first principles, and examples of existing transforms are brought together from the literature. The method allows a large rank matrix to be represented by a relatively small number of parameters, and it is shown how information that is not provided explicitly is filled in. Methods use dynamical properties of the atmosphere (e.g. balance relationships) and make assumptions about the way that background errors are spatially correlated (e.g. homogeneity and isotropy in the horizontal). It is also common to assume that the B -matrix is static. The way that these, and other, assumptions are built into systems is shown. The article gives an example of how a current method performs. An important part of this article is a discussion of some new ideas that have been proposed to improve the method. Examples include how a more appropriate use of balance relations can be made, how errors in the moist variables can be treated and how assumptions of homogeneity/isotropy and the otherwise static property of the B -matrix can be relaxed. Key developments in the application of dynamics, wavelets, recursive filters and flow-dependent methods are reviewed. The article ends with a round up of the methods and a discussion of future challenges that the field will need to address. Copyright © 2008 Royal Meteorological Society [source] Capital cities: When do they stop growing?,PAPERS IN REGIONAL SCIENCE, Issue 1 2002Kristof Dascher Capital city; public goods; urban growth Abstract This article is an attempt to explain a capital city's size. We assume away explanations such as exploitation of the capital city's hinterland. Instead, we emphasise the role of the localisation of government activity (i.e., administration or legislation) in the capital city for both the capital city economy and the hinterland economy. We assume in the model that larger regions benefit from agglomeration economies. We discuss the interaction of those agglomeration economies with an agglomeration diseconomy specific to the capital city. Under certain conditions, a stable population distribution between the capital city and its hinterland emerges where neither region captures the entire population. We also analyse the comparative statics properties of this stable equilibrium. 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