104,416 research outputs found
Ride Analysis For Suspension System of off-Road Tracked Vehicles
No full textIn this work. an attempt has been made to develop a programming package
for ride analysis of off-road vehicles based upon a finite-element
formulation of vehicle suspension systems. Mathematical modelling of
generalised suspension systems has been carried out with several
non-linear aspects being investigated and implemented in the programming
package. such as large deflection. non-linear characteristics of springs
and dampers. bump stops and wheel separation. Different types of soi 1
have been considered together with an appropriate modelling of vehicle
tracks. Several methods for time integration of dynamic equations have
been investigated so as to deal wi th numerical instabi 1 i ty problems
expected for off-road suspension systems which often have "stiff"
differential equations of motion. Three ride analysis criteria have also
been considered in the programming package. Several case studies have been analysed using the developed programming
package. They consist of two simple case studies with known analytical
solutions. an existing wheeled off-road vehicle with published analog
computer resul t s , and an off-road tracked vehicle wi th known
experimental results. The package has been validated and proved to be an
acceptable tool for the ride analysis of off-road vehicles. within the
approximating assumptions considered. Several measures for future
development have also been suggested
An efficient numerical algorithm for the transient analysis of high-frequency non-linear circuits
No full textThe paper proposes a new approach for the discrete-time integration of non-linear differential equations that describe the behaviour of high-frequency circuits, in particular those containing complex equivalent-circuit models of microwave transistor devices. The proposed approach reformulates a conventional predictor-corrector method in terms of Pad�© approximates about each function sample. The method is especially suited to the kind of non-linear stiff differential equations that arise frequently in high-frequency analysis
Gad65 is recognized by t-cells, but not by antibodies from nod-mice
No full textSince the 64kDa-protein glutamic acid decarboxylase (GAD) is one of the major autoantigens in T-cell mediated Type 1 diabetes, its relevance as a T-cell antigen needs to be clarified. After isolation of splenic T-cells from non-obese diabetic (NOD) mice, a useful model for human Type 1 diabetes, we found that these T-cells proliferate spontaneously when incubated with human GAD65, but only marginally after incubation with GAD67, both recombinated in the baculovirus system. No effect was observed with non-diabetic NOD mice or with T-cells from H-2 identical NON-NOD-H-2g7 control mice. It has been published previously that NOD mice develop autoantibodies against a 64kDa protein detected with mouse beta cells. In immunoprecipitation experiments with sera from the same NOD mice and 33S-methionine-labelled GAD, no autoantibody binding could be detected. We conclude firstly that GAD65 is an important T-cell antigen which is relevant early in the development of Type 1 diabetes and secondly that there is an antigenic epitope in the human GAD65 molecule recognized by NOD T-cells, but not by NOD autoantibodies precipitating conformational epitopes. Our results therefore provide further evidence that GAD65 is a T-cell antigen in NOD mice, being possibly also involved in very early processes leading to the development of human Type 1 diabetes
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
Difference Methods for Stiff Delay Differential Equations
No full textDelay differential equations of the form y'(t) = f(y(t), z(t)), where z(t) = {y(,1)((alpha)(,1)(y(t))),..., y(,n)((alpha)(,n)(y(t)))}('T) and (alpha)(,i)(y(t)) (LESSTHEQ) t arise in many scientific and engineering fields when transport lags and propagation times are physically significant in a dynamic process. Difference methods for approximating the solutions of stiff delay systems require special stability properties that are generalizations of those employed for stiff ordinary differential equations. Using the model equation (y'(t) = py(t) + qy(t-1), with complex p and q, the definitions of A-stability, (A((alpha))-stability, and stiff stability have been generalized to delay equations. For linear multistep difference formulas, these properties extend directly from ordinary to delay equations. This is not true for implicit Runge-Kutta methods, as illustrated by the mid-point formula, which is A-stable for ordinary equations, but not for delay equations.A computer code for stiff delay equations was developed using the stiffly stable backward differentiation formulae (BDF). In a three-way comparison with non-stiff Adam's and Runge-Kutta methods, the BDF method required significantly less computation for stiff problems and only slightly more computation for non-stiff problems.Made available in DSpace on 2014-12-13T18:02:21Z (GMT). No. of bitstreams: 1
8114471.pdf: 3838652 bytes, checksum: 9da590d77361d271f219672807648195 (MD5)
Previous issue date: 1981Embargo set by: Seth Robbins for item 66628
Lift date: Forever
Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDsRestricted to the U of I community idenfinitely during batch ingest of legacy ETDsU of I Only142 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981
Legal regulation of prices in Tanzania : an examination of the Regulation of Prices Act 1973 as a tool of social change and development
No full textDrawing mainly from the Tazanian experience this study
attempts to review the principal issues in the legal regulation of
prices, by identifying both the general and specific importance
of law in this respect. The position I shall present is that
legal control is both necessary and desirable for the welfare
and social development of the people. The key issue is whether
the market-place will perform its function satisfactory: Will
it produce socially desirable results? If it will not, why will
it not? And will legal regulation help to do the job a little
better?
In an attempt to answer some of these questions,
first of all, outline the basic issues raised by the study in
the first Chapter. Then I examine the general case for price
controls - the theory about the controls, the motives and reasons
for their imposition and the manner in which they are effected
in different economic systems. This is done in Chapter Two. Relying
most on the available literature on the regulatory process, this
Chapter also looks at the relationship between law and economic
regulation and concludes that the effectiveness of law depends
on the existence of a conducive socio-economic environment. In
Chapter Three I describe the past record of price control laws
in Tanzania. I conclude that despite the failure in the past,
the controls still constitute an important policy instrument
in the transition to socialism. In Chapters Four and Five I describe
the manner in which the current regulations are implemented and
the problems encountered. I conclude that the operational performance
of the controls is constrained by internal and external influences on the economic and political life of the country. In the concluding
Chapter I assess the impact of the controls: Do the controls
work? Do people buy goods at the controlled prices? Why today
the controls are almost popularly accepted as worthwhile? I conclude
that while there may be no measurable economic gains derived
by consumers, the controls have a stabilising effect on the social
and political front. In the final section I argue that the
future success of the legislation depends on creating a correspondence
between the economic structures and the control system. What
makes the controls ineffective is not so much defects in the
law but the contradictions between the orientation of and functioning
of the economic system and the ideological commitment
Effective simulation techniques for biological systems
No full textIn this paper we give an overview of some very recent work on the stochastic simulation of systems involving chemical reactions. In many biological systems (such as genetic regulation and cellular dynamics) there is a mix between small numbers of key regulatory proteins, and medium and large numbers of molecules. In addition, it is important to be able to follow the trajectories of individual molecules by taking proper account of the randomness inherent in such a system. We describe different types of simulation techniques (including the stochastic simulation algorithm, Poisson Runge-Kutta methods and the Balanced Euler method) for treating simulations in the three different reaction regimes: slow, medium and fast. We then review some recent techniques on the treatment of coupled slow and fast reactions for stochastic chemical kinetics and discuss how novel computing implementations can enhance the performance of these simulations
Síndrome da pele endurecida: relato de caso e revisão da literatura.
No full textTrabalho de Conclusão de Curso - Universidade Federal de Santa Catarina. Curso de Medicina. Departamento de Clínica Médica
Recommended from our members
Ground movements due to excavation in clay: physical and analytical models
No full textIn view of the recent catastrophes associated with deep excavations, there is an urgent need to provide vital guidelines on the design of the construction process. To develop a simple tool for predicting ground deformation around a deep excavation construction for preliminary design and decision-making purposes, small scale centrifuge models were made to observe the complicated mechanisms involved.
A newly developed actuation system, with which the construction sequences of
propping could be implemented, was developed, the new procedures were proven to give more realistic initial ground conditions before excavation with minimal development of pre-excavation bending moment and wall displacement. Incremental wall deformation profiles generally followed the O’Rourke cosine bulge equation and a new deformation mechanism was proposed with respect to wall toe fixity and excavation geometry.
Validation of the conservation energy principle was carried out for the undrained
excavation process. The total loss of potential energy was shown to be balanced by the total work done in shearing and the total elastic energy stored in structures with an error term of 30%.
An improved mobilizable strength method (MSD) method using observed mechanistic deformation patterns was introduced to calculate the displacement profile of
a multi-propped undrained excavation in soft clay. The incremental loss in potential
energy associated with the formation of settlement toughs was balanced by the sum of
incremental storage of elastic energy and the energy dissipation in shearing. A reasonable agreement was found between the prediction by the MSD method and the finite element results computed by an advanced MIT-E3 model for wall displacements, ground
settlement, base heave and bending moment on fixed base walls. For cases of excavations
supported by floating walls, the effect of embedded wall length, depth of the stiff layer, bending stiffness of wall and excavation geometry and over-consolidation ratio of soils were found to have a influence on the maximum wall deflection. In general, the predictions fell within 30% of the finite element computed results.
A new chart ψ versus normalized system stiffness was used to demonstrate that MSD
could correctly capture the trend of wall displacements increasing with the ratio of
excavation depth to depth of stiff layer, which could be controlled by increasing wall
stiffness for very stiff wall system only. The incorporation of a simple parabolic curve
quantifying small strain stiffness of soil was proven to be essential to good ground
movement predictions. A new dimensionless group has been defined using the MSD
concepts to analyze 110 cases of excavation. The new database can now be used to
investigate the relationship between structural response ratio S and soil-structure stiffness ratio R where this is shown on log-log axes to capture the enormous range of wall stiffness between sheet-piles and thick diaphragm walls. Wall stiffness was found to have a negligible influence on the magnitude of the wall bulging displacements for deep excavation supported by fixed-based wall with stiffness ranging from sheet pile walls to ordinary reinforced concrete diaphragm walls, whereas excavations supported by floating walls were found to be influenced by wall stiffness due to the difference in deformation mechanisms
Cytoplasmic islet cell antibodies recognize distinct islet antigens in IDDM but not in stiff man syndrome
No full textCytoplasmic islet cell antibodies are well-established predictive markers of IDDM. Although target molecules of ICA have been suggested to be gangliosides, human monoclonal ICA of the immunoglobulin G class (MICA 1-6) produced from a patient with newly diagnosed IDDM recognized glutamate decarboxylase as a target antigen. Here we analyzed the possible heterogeneity of target antigens of ICA by subtracting the GAD-specific ICA staining from total ICA staining of sera. This was achieved 1) by preabsorption of ICA+ sera with recombinant GAD65 and/or GAD67 expressed in a baculovirus system and 2) by ICA analysis of sera on mouse pancreas, as GAD antibodies do not stain mouse islets in the immunofluorescence test. We show that 24 of 25 sera from newly diagnosed patients with IDDM recognize islet antigens besides GAD. In contrast, GAD was the only islet antigen recognized by ICA from 7 sera from patients with stiff man syndrome. Two of these sera, however, recognized antigens besides GAD in Purkinje cells. In patients with IDDM, non-GAD ICA were diverse. One group, found in 64% of the sera, stained human and mouse islets, whereas the other group of non-GAD ICA was human specific. Therefore, mouse islets distinguish two groups of non-GAD ICA and lack additional target epitopes of ICA besides GAD. Longitudinal analysis of 6 sera from nondiabetic ICA+ individuals revealed that mouse-reactive ICA may appear closer to clinical onset of IDDM in some individuals
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