1,589 research outputs found

    Identification of inelastic parameters of the 304 stainless steel using multi-objective techniques

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    This work addresses identiïŹcation of inelastic parameters based on an optimization method using a multi-objective technique. The problem consists in determining the best set of parameters which approximate three diïŹ€erent tensile tests. The tensile tests use cylindrical specimens of diïŹ€erent dimensions manufactured according to the American ASTM E 8M and Brazilian ABNT NBR ISO 6892 technical standards. A tensile load is applied up to macroscopic failure. The objective functions for each tensile test/specimen is computed and a global error measure is determined within the optimization scheme. The Nelder-Mead simplex algorithm is used as the optimization tool. The proposed identiïŹcation strategy was able to determine the best set of material parameters which approximate all tensile tests up to macroscopic failure

    Further studies on identification of inelastic parameters for damaged materials

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    A proper set of material parameters is one of the most important aspects for a successful simulation of metal forming processes. Several issues must be observed when choosing the constitutive relation and corresponding material parameters, amongst which the most important are: (i) the magnitude of the plastic deformation of the target forming operation must be contemplated by the parameters of the constitutive model, (ii) possibility of failure prediction in fracture-free materials, and (iii) accurate prediction of geometrical changes caused by plastic deformation. Within this framework, the present article discusses techniques to obtain constitutive parameters of a Lemaitre-type material model. The strategy requires compliance of multiple tensile tests with specimens prepared according to diïŹ€erent technical standards. Parameter identiïŹcation is regarded as an inverse problem and solved using optimization methods

    The Effect of Wearing an Obese Body Suit on Snack Food Consumption and Alcohol Consumption

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    A previous study showed that wearing an obese body suit results in increased snack food consumption. The aim of this study was to explore mechanisms that may explain the effect that wearing an obese body suit has on snack food consumption. We examined two potential explanations; that the psychosocial experience of being overweight resulted in stereotype consistent behaviour (overeating) or in impairments to self-control. Ninety-four women participated in a laboratory study in which they were asked to wear an obese body suit or control clothing in a public setting, before being given access to snack food and alcohol. Clothing condition had no effect on snack food or alcohol consumption. It is possible that the presence of alcohol in the taste test removed the previously observed effect of the obese body suit on snack food consumption

    Operator algebras from the discrete Heisenberg semigroup

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    We study reflexivity and structure properties of operator algebras generated by representations of the discrete Heisenberg semi-group. We show that the left regular representation of this semi-group gives rise to a semi-simple reflexive algebra. We exhibit an example of a representation which gives rise to a non-reflexive algebra. En route, we establish reflexivity results for subspaces of H^{\infty}(\bb{T})\otimes\cl B(\cl H)

    A Schmidt number for density matrices

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    We introduce the notion of a Schmidt number of a bipartite density matrix, characterizing the minimum Schmidt rank of the pure states that are needed to construct the density matrix. We prove that Schmidt number is nonincreasing under local quantum operations and classical communication. We show that kk-positive maps witness Schmidt number, in the same way that positive maps witness entanglement. We show that the family of states which is made from mixing the completely mixed state and a maximally entangled state have increasing Schmidt number depending on the amount of maximally entangled state that is mixed in. We show that Schmidt number {\it does not necessarily increase} when taking tensor copies of a density matrix ρ\rho; we give an example of a density matrix for which the Schmidt numbers of ρ\rho and ρ⊗ρ\rho \otimes \rho are both 2.Comment: 5 pages RevTex, 1 typo in Proof Lemma 1 correcte

    Long-term calorie restriction in humans is not associated with indices of delayed immunologic aging: A descriptive study.

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    BACKGROUND: Delayed immunologic aging is purported to be a major mechanism through which calorie restriction (CR) exerts its anti-aging effects in non-human species. However, in non-obese humans, the effect of CR on the immune system has been understudied relative to its effects on the cardiometabolic system. OBJECTIVE: To examine whether CR is associated with delayed immunologic aging in non-obese humans. METHODS: We tested whether long-term CR practitioners (average 10.03 years of CR) evidenced decreased expression of T cell immunosenescence markers and longer immune cell telomeres compared to gender-, race/ethnicity-, age-, and education-matched "healthy" Body Mass Index (BMI) and "overweight"/"obese" BMI groups. RESULTS: Long-term human CR practitioners had lower BMI (p <  0.001) and fasting glucose (p <  0.001), as expected. They showed similar frequencies of pre-senescent cells (CD8+CD28- T cells and CD57 and PD-1 expressing T cells) to the comparison groups. Even after adjusting for covariates, including cytomegalovirus status, we observed shorter peripheral blood mononuclear cell telomeres in the CR group (p = 0.012) and no difference in granulocyte telomeres between groups (p = 0.42). CONCLUSIONS: We observed no clear evidence that CR as it is currently practiced in humans delays immune aging related to telomere length or T cell immunosenescent markers

    Immunological Pathogenesis of Endolymphatic Hydrops and Its Relation to Meniere\u27s Disease

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    This study was designed to investigate an immunologically induced endolymphatic hydrops (ELH) and to focus on the issue of its pathogenesis in relation to Meniere\u27s disease. The time course of ELH was evaluated by light microscopy in a 2-hour to 7-month period following direct antigen challenge to the endolymphatic sac (ELS) in systemically pre-sensitized guinea pigs. ELH began to appear in the vestibule and the basal turn 5-7 hours after inner ear challenge and developed gradually. During the interval from the second day to the first week, ELH rapidly developed in all the cochlear turns and reached a maximum size. During the period from the second week to the eighth week, ELH gradually reduced. After 9 weeks, ELH of the saccule and the cochlea gradually recurred. During the interval from the first week to the eighth week, the time course of ELH correlated well with the grade of cellular infiltration of the perisaccular tissue. These results suggest that recurrent immunological reaction in the ELS may result in disorders of the ELS which finally lead to the onset of Meniere\u27s disease

    Equilibrium Statistical Mechanics of Fermion Lattice Systems

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    We study equilibrium statistical mechanics of Fermion lattice systems which require a different treatment compared with spin lattice systems due to the non-commutativity of local algebras for disjoint regions. Our major result is the equivalence of the KMS condition and the variational principle with a minimal assumption for the dynamics and without any explicit assumption on the potential. It holds also for spin lattice systems as well, yielding a vast improvement over known results. All formulations are in terms of a C*-dynamical systems for the Fermion (CAR) algebra with all or a part of the following assumptions: (I) The interaction is even with respect to the Fermion number. (Automatically satisfied when (IV) below is assumed.) (II) All strictly local elements of the algebra have the first time derivative. (III) The time derivatives in (II) determine the dynamics. (IV) The interaction is lattice translation invariant. A major technical tool is the conditional expectation from the total algebra onto the local subalgebra for any finite subset of the lattice, which induces a system of commuting squares. This technique overcomes the lack of tensor product structures for Fermion systems and even simplifies many known arguments for spin lattice systems.Comment: 103 pages, no figure. The Section 13 has become simpler and a problem in 14.1 is settled thanks to a referee. The format has been revised according to the suggestion of this and the other referee
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