Assumptions Of Analysis Research Articles

The optimal design method of permanent magnet assemblies with completely open architecture for MRI

This paper presents a flexible design method to facilitate the construction of permanent magnet assemblies with completely open architectures for the Magnetic Resonance Imaging (MRI). The initial design is based on the ideally analytical assumptions. Then the dimensions and directions of the magnetization of each permanent element are optimized by using a modified genetic algorithm. Numerical implementations show that the proposed method provides a main magnetic field with modified homogeneity and strength at the imaging region, which is defined outside of the magnet structure, and minimizes the cost of the MRI equipment.

Quantitative Evaluation of the Effects of Hydrogeological Boundary and Initial Conditions on Slug Tests

In analytical models for the slug test, it is assumed that the hydraulic head distribution within a formation is initially at equilibrium and that the hydrogeological boundaries can be defined deterministically. In practice, however, the hydraulic head distribution may be varied, e.g., by fluid injection during the drilling process before a test or by repeated testing, and it may not be possible to ascertain the hydrogeological boundary conditions. The discrepancies between model assumptions and actual conditions may affect the reliability of the data derived analytically from a slug test. The present study examines these problems using a numerical approach. The results showed that: (1) variations in the background hydraulic head caused by drilling or repeated testing may affect estimation of hydraulic properties, especially the value of specific storage; and that (2) discrepancies between the actual hydrogeological boundary conditions and analytical assumptions may cause significant errors in specific st...

Diasporic Nationalism, Citizenship, and Post-War Reconstruction

While ties between Cambodian diasporas and Cambodia have been significant and enduring over the decades of conflict, the political changes engendered by the internationally endorsed elections of 1993 have transformed the scope and characteristics of the transnational traffic. Shaped by complex ideological, class, gender, and generational dynamics, Cambodian diasporas’ re-engagement with the ancestral homeland has since acquired a multidimensionality that extends beyond mere monetary remittance. Spanning both private and public spheres, from national to household levels, these transnational encounters necessarily dislodge the narrow analytic focus and assumptions that accompany much of the discourse of transnationalism, and interrogate critical issues of nationalism, citizenship, and belonging.

TO BE “EMPLACED”: FUZHOUNESE MIGRATION AND THE POLITICS OF DESTINATION

This article offers an exploration of what it means to be “emplaced” amidst the various spatial and temporal streams currently flowing through an emigrant village in the Fuzhou countryside along the southeast coast of China. These flows include both transnational currents resulting from two decades of mass emigration via human smuggling networks to the United States and other foreign destinations as well as national and translocal currents driven in part by Post-Mao reforms for market liberalization and China’s “opening up” (kaifang). Particularly, I aim to provide a corrective to the overemphasis of displacement as an experience outside of “home” and moreover, to the mystification of “home” sites as imaginary places simply of longing and belonging. My goal is not to dismiss symbolic understandings of mythical homelands but rather to better contextualize and refine assumptions of migrant displacement in relation to imaginations of locality and belonging from the empirical and phenomenological grounds of those who remained behind. Significantly, approaching issues of migrant identities and social formations from the location of dispersion rather than arrival enabled me to critically examine and situate existing analytic assumptions of displacement (e.g., as migrant nostalgia for “home”) alongside local theorizations of emplacement made by those who stayed put as others moved around them. As I will show for my Fuzhounese subjects, the ultimate form of displacement was seen and experienced as the result of immobility, rather than physical departure from a “home.”

Numerical modelling of orthogonal cutting: Influence of cutting conditions and separation criterion

Chip formation is a high strain rate process studied with analytical and numerical models. Analytical models have the advantage of a small calculation time, however, they are often based on some assumptions which are difficult to verify. Finite element modelling (FEM) of chip formation process provides more details on the chip process formation, such as plastic strain, strain rate or stress fields. FEM can be used to improve the analytical models' assumptions. There is still a wide dispersion of formulations and numerical parameters adopted in order to obtain accurate results in numerical models. In the Lagrangian approach, it is of crucial importance to establish realistic criteria for element deletion, allowing chip separation from original workpiece. In the arbitrary Lagrangian Eulerian (ALE) formulation no element deletion is needed. This work is focused in modelization of orthogonal cutting. A comparison between both numerical approaches, Lagrangian and ALE is shown. The effects of geometrical parameters, erosion criterion and cutting speed are evaluated. Comparisons between numerical and theoretical results are performed, and the results obtained from the numerical approach are used as an input of analytical model, improving its accuracy.

Buckling Strength of Single Angle Compression Members in K-Series Joists

Single angle web members in open web steel joists are typically crimped to facilitate web placement and maintain a constant chord gap with varying web angle size. If the web members are not crimped force eccentricity will exist between the web member's area centroid and the vertical plane of symmetry for the joist. The analytical consequence of this eccentricity is that uncrimped single angle web members must be designed as eccentrically loaded columns. The resulting interaction design strength is significantly less than the concentric column analysis design strength used for crimped web members of identical cross section and slenderness. This study compares the measured and analytical strengths of like single angle L1x1x7/64 inch crimped and uncrimped web members in steel joists. Experimental results from 18 joist samples show that existing analytical assumptions associated with end fixity and beam-column interaction result in an overly conservative design methodology for both crimped and uncrimped web members.

Gravitational recoil during binary black hole coalescence using the effective one body approach

Using the Effective One Body approach, that includes nonperturbative resummed estimates for the damping and conservative parts of the compact binary dynamics, we compute the recoil during the late inspiral and the subsequent plunge of non-spinning black holes of comparable masses moving in quasi-circular orbits. Further, using a prescription that smoothly connects the plunge phase to a perturbed single black hole, we obtain an estimate for the total recoil associated with the binary black hole coalescence. We show that the crucial physical feature which determines the magnitude of the terminal recoil is the presence of a ``burst'' of linear momentum flux emitted slightly before coalescence. When using the most natural expression for the linear momentum flux during the plunge, together with a Taylor-expanded $(v/c)^4$ correction factor, we find that the maximum value of the terminal recoil is $\sim 74$ km/s and occurs for a mass ratio $m_2/m_1 \simeq 0.38$. We comment, however, on the fact that the above `best bet estimate' is subject to strong uncertainties because the location and amplitude of the crucial peak of linear momentum flux happens at a moment during the plunge where most of the simplifying analytical assumptions underlying the Effective One Body approach are no longer justified. Changing the analytical way of estimating the linear momentum flux, we find maximum recoils that range between 49 and 172 km/s. (Abridged)

Foundations of the functional approach for signal analysis

In this paper, the mathematical foundation of the functional (or nonstochastic) approach for signal analysis is established. The considered approach is alternative to the classical one that models signals as realizations of stochastic processes. The work follows the fraction-of-time probability approach introduced by Gardner. By applying the concept of relative measure used by Bochner, Bohr, Haviland, Jessen, Wiener, and Wintner and by Kac and Steinhaus, a probabilistic—but nonstochastic—model is built starting from a single function of time (the signal at hand). Therefore, signals are modeled without resorting to an underlying ensemble of realizations, i.e., the stochastic process model. Several existing results are put in a common, rigorous, measure-theory based setup. It is shown that by using the relative measure concept, a distribution function, the expectation operator, and all the familiar probabilistic parameters can be constructed starting from a single function of time. The new concept of joint relative measurability of two or more functions is introduced in this paper which is shown to be necessary for the joint characterization of signals. Moreover, by using such a concept, the independence of signals is defined. The joint relative measurability property is then used to prove the nonstochastic counterparts of several useful theorems for signal analysis. It is shown that the convergence of parameter estimators requires (analytical) assumptions on the single function of time that are much easier to verify than the classical ergodicity assumptions on stochastic processes. As an example of application, nonrelatively measurable functions are shown to be useful in the design of secure information transmission systems.

Predictions of Tragedy vs. Tragedy of Predictions in Northeast Asian Security

Abstract The main argument of this article is that most structure-oriented IR predictions about the future of Northeast Asia in the aftermath of the Cold War have been overwhelmingly pessimistic, thereby projecting a tragic regional order. They have failed to assess the progressive trends of regional interactions, mainly because their projections were blinded by the structure-oriented theoretical conjectures. My paper has three objectives: First, I attempt to empirically identify the diverging gap between the pessimistic predictions about the future of Northeast Asia made by the mainstream IR analysts and scholars during the post-Cold War era and the reality of the past 15 years, which has been relatively well-coordinated, cooperative, and surprisingly peaceful. I unpack the logical structure of these predictions and theoretically explain the reasons why there has been an increasing gap between the two. Second, I argue that conventional arguments about the future of Northeast Asia tend to overemphasize a few structural variables dictated by their theories, while underspecifying regional factors such as regional states' conscious efforts to manage the regional order. Lastly, I draw analytical implications that the actual choices made by state leaders of Northeast Asia must be the target of empirical examinations, not analytical assumptions.

Determining the Transport Properties of Rock Specimens Using an Improved Laboratory Through-Diffusion Technique

ABSTRACTThe safe disposal of radioactive nuclear wastes using multi-barrier systems requires a good understanding of their transport properties in geological materials. When groundwater flow is very slow, the most important mechanisms of transport and retardation are diffusion through and sorption onto geological materials, and an evaluation of relevant parameters, particularly the effective diffusion coefficient and rock capacity factor (or sorption coefficient), is of fundamental importance to any safety assessment. Although laboratory diffusion tests can be used to determine these two parameters, conventional through-diffusion testing has some limitations, such as the need for a relatively long test time, cumbersome test procedures and the possibility of errors due to differences between analytical assumptions and actual test conditions. In this paper, we offer a rigorous solution to the through-diffusion test. Boundary conditions are improved by taking into account concentration changes in both the source and the measurement cells. A companion approach for back-calculating the effective diffusion coefficient and rock capacity factor is also proposed. The effectiveness and advantages of this improved technique are demonstrated using experimental data derived from a sedimentary rock sample taken from a research site in Japan.

Decision Effects, the Hahn–Jordan Decomposition for States, and Their Connection to Ludwig’s Axiomatic Approach to Quantum Mechanics

We begin with a quantum logic carrying a large collection of states. We then form a dual pair of Banach spaces—base normed and order unit normed—containing the states and the logic, respectively. A Galois connection on the face lattices of the states and the dual positive order unit interval is introduced. The elements of the logic are connected to a dense subset of the extreme points of this order interval in the order unit space using a generalized form of the Hahn–Jordan decomposition theorem. Decision effects are defined and identified with the elements of the original logic. Finally, an important axiom of Ludwig is introduced which ties together all the lattices of Galois closed faces of states, Galois closed order intervals of the positive order unit interval, decision effects, and the original quantum logic. The emphasis here is on the consequences of functional analytic assumptions. The paper concludes with a simple example where Ludwig’s axiom does not hold and we see parts of the theory dissolve.

Effect of Loading on Stress Intensification Factors

The basic objective of this investigation is to determine the effect of loading on the stress intensification factors of Markl’s fatigue evaluation method for metal piping. Markl’s method is based on the fatigue testing of 4 in. schedule 40 carbon steel cantilever piping. Subsequent testing using a four-point loading showed that the S-N data were different from that predicted by the procedure and equation developed by Markl. Markl’s method is based on determining the elastic-plastic forces in a piping system by multiplying the elastic system stiffness by the actual deflection. In this manner a fictitious force is calculated to determine piping stresses assuming the elastic beam bending equation, Mc/I, applies even in partially plastic pipes. Previous analytical work on this topic by Rodabaugh and Scavuzzo (“Fatigue of Butt Welded Pipe and the Effect of Testing Methods–Report 2: Effect of Testing Methods on Stress Intensification Factors,” Welding Research Bulletin 433, July 1998) showed that these measured differences should occur between cantilever and four-point tests using Markl’s method. The basic assumption in this analytical comparison is that strain-cycle correlations lead to the correct prediction of fatigue life. Using the measured alternating strain, both types of test geometries lead to the same prediction of fatigue life using these strain-cycle correlations. In this study, the same analytical assumptions used by Rodabaugh and Scavuzzo (above) are applied to a pipe where the load is varied from a four-point loading through its extremes. Loads were varied from a cantilever to an end moment by changing the dimensions of four-point loading. Also, the shape of a bilinear stress-strain curve was varied from a perfectly plastic material to various degrees of work hardening by increasing the tangent modulus in the plastic regime. The results of the study indicate that Markl’s method is conservative by predicting too short a fatigue life for four-point loading for a given stress. As indicated by this study, the differences can be very large in the low-cycle regime for a perfectly plastic material and for a four-point loading approaching an end moment. Thus, piping could be over designed with unnecessary conservatism using the current ASME Code method based on stress intensification factors.

Analytic Choices in Economic Models of Treatments for Rheumatoid Arthritis: What Makes a Difference?

To compare the analytic judgments, data, and assumptions of different models used in the economic evaluation of infliximab, one of a new class of drugs for rheumatoid arthritis (RA). A detailed assessment was made of 4 models, 1 submitted (in a reimbursement dossier) by the manufacturer, 1 produced by an independent academic group, and 2 recently published in the literature. Factors considered included the key data inputs, assumptions about the sequencing of treatments for RA, the methods used to calculate health utilities, and the estimation of cost offsets. Two of the 4 models, although embodying different methodological approaches, gave fairly similar results (approximately 25,000 pounds- 35,000 pounds cost per additional quality-adjusted life year [QALY] gained). The other 2 models, both by an independent academic group, gave much higher estimates, ranging from 50,000 pounds to 60,000 pounds to more than 100,000 pounds per additional QALY. The differences appeared to depend mainly on differences in model structure, the assumptions about the positioning of infliximab in the treatment sequence, and the relationship between Health Assessment Questionnaire (HAQ) states and QALYs. Economic models of treatments for RA incorporate different key data inputs and analytic judgments. However, convergence was observed in some of the estimates produced by the models, particularly when adjustments were made for some of the differences in input parameters. Nevertheless, differences in the choice of model structure and in key assumptions also had a major impact on results. Therefore, more discussion is needed to reach a consensus on some of these methodological issues.

Conspiracy theory and the critical enterprise

This paper explores the argumentative work undertaken in talk and text about conspiracy theory (CT), relating this to recent scholarly debate regarding the significance of critical inquiry in the context of developments in poststructuralist and postmodern social theory. We examine discussion of CT as a site where the transformation between deconstructive, depth analytic critique and its opposite, realist claims takes place. Meta-theoretical formulations attempting to accommodate both such argumentative gestures in a coherent program for the pursuit of dialogue are shown to be inconsistent with the nature of argumentation as an undertaking to resolve ambiguity in accounts. The sharing of concerns on which agreement is to be founded are the outcome, rather than the basis, of dialogue, even if such an encounter is pursued on the grounds of shared presupposition distinct from the shared concerns which emerge from dialogue. Discussion concerning CT is a site where the formulation of motivation is made to bear on the question of an argument’s validity in virtue of either depth analytic or realist assumptions.

Some further thoughts on the subject of ‘internal cohabitation’ and the genesis of an ‘other’: A response to Tim Wright's paper ‘Art therapy and the concept of internal cohabitation’

This paper is a response to Tim Wright's article ‘Art Therapy and the Concept of Internal-Cohabitation’ (Inscape, Volume 9, No.1 2004, pp. 26–37). Wright presented his work using a potentially universally applicable model of the mind(s). I begin to look at the complexity of his argument and open up some of the debates around the genesis of an ‘other’ mind. For example, is it an aspect of the self or not? If there is an ongoing, internal view different to the one identified as a relational self, how is it formed? And can this ‘other’ presence offer a benign hand in creativity? Whilst I do not endeavour to provide answers to these questions I support the notion that part of the art therapy work needs to involve an exploration of the validity of some analytic assumptions about ‘self’ and ‘other’ if there is to be a consistent, non-contradictory approach.

지진하중을 받는 전단구조물의 1차 모드참여계수 산정

지진하중을 받는 구조물은 모드참여계수에 의하여 각각의 모드에 지진하중이 분배, 전달된다. 이러한 특성 때문에 모드참여계수는 지진하중을 받는 구조물의 해석에서 매우 중요한 요소이다. 그러나 이상화된 해석 구조물의 모드참여계수는 해석적 모델링이나 시공오차 등에 의하여 실 구조물의 참여계수와 다르기 때문에 실제 거동을 예측, 반영하기에 한계가 있다. 본 연구에서는 시스템 식별기술과 <TEX>$H^{\infty}$</TEX> 최적 모델 응축법을 활용하여, 구조물의 1차 모드참여계수를 산정하는 기법을 제안한다. 이 기법은 시스템 식별로부터 구현된 상태방정식을 전형의 상태방정식과 비교하는 과정에서 시스템의 가제어, 가관측 행렬의 비에 의하여 결정된다. 본 연구에서 제안한 모드참여계수산정기법은 단자유도, 다자유도 전단구조물에 대한 수치해석을 통하여 검증하였다. Seismic load is distributed to modes of a structure through the modal participation factor(MPF). The modal participation factor is essential to analyze structural response under earthquake load. MPF of a real structure differs from that of analytical mathematical model due to the error induced from analytical assumptions and during the construction. In this study, an identification method is proposed to calculate the 1st MPF of real structure based on <TEX>$H^{\infty}$</TEX> optimal model reduction. The MPF is obtained from the relationship between observability and controllability matrices realized from system identification and those of a prototype 2-degree state space model. The proposed method is verified thorough numerical examples.

The Potential Impact of Vouchers

This article provides an updated review of recent empirical research on the potential impact of private school vouchers. It addresses 3 questions: (a) do students that use vouchers to attend a private school obtain better outcomes than would be obtained in a public school? (b) Do vouchers encourage student sorting and how does sorting affect student outcomes? (c) Does the offer of vouchers promote competition, improving outcomes of students who remain in public schools? Conclusions are that African American students who are offered vouchers experience small achievement gains. The results are highly sensitive to analytical assumptions and are not evident for other racial or ethnic groups. The evidence further indicates that large-scale voucher plans encourage sorting that could lower the achievement of public school students. There is no compelling evidence that such losses are outweighed by competitive gains in public schools. The conclusions on sorting and competition are most applicable to unrestricted choice plans in which flat-rate vouchers are offered to a large number of students with few eligibility restrictions. Some emerging evidence indicates that alternate approaches to policy design could yield more promising results.

On the construction of global coordinate systems in Euclidean spaces

Several techniques for constructing global coordinate systems in R n adapted to functions are given. Some of these techniques are based on geometrical assumptions and other ones on analytical assumptions.

Fundamental Modeling and Thermal Performance Issues for Metallic Thermal Protection System Concept

A study was performed to develop an understanding of the key factors that govern the performance of metallic thermal protection systems for reusable launch vehicles. A current advanced metallic thermal protection system concept was systematically analyzed to discover the most important factors governing its thermal performance. A large number of relevant factors that influence the thermal analysis and thermal performance system were identified and quantified. Detailed finite element models were developed for predicting the thermal performance of design variations of the metallic thermal protection system concept mounted on a simple, unstiffened structure. The computational models were also used, in an automated iterative procedure, for sizing the metallic thermal protection system to maintain the structure below a specified temperature limit. A statistical sensitivity analysis method, based on orthogonal matrix techniques used in robust design, was used to quantify and rank the relative importance of the various modeling and design factors considered in this study. Thermal performance was shown to be sensitive to several analytical assumptions that should be chosen carefully. Of the design factors studied, the heat capacity of the underlying structure was found to have the greatest effect on thermal performance. Therefore the structure and thermal protection system should be designed concurrently.

Theory, Stylized Heuristic or Self‐Fulfilling Prophecy? The Status of Rational Choice Theory in Public Administration

Rational choice is intimately associated with positivism and naturalism, its appeal to scholars of public administration lying in its ability to offer a predictive science of politics that is parsimonious in its analytical assumptions, rigorous in its deductive reasoning and overarching in its apparent applicability. In this paper I re‐examine the ontology and epistemology which underpins this distinctive approach to public administration, challenging the necessity of the generally unquestioned association between rational choice and both positivism and naturalism. Rational choice, I contend, can only defend its claim to offer a predictive science of politics on the basis of an ingenious, paradoxical, and seldom acknowledged structuralism and a series of analytical assumptions incapable of capturing the complexity and contingency of political systems. I argue that analytical parsimony, though itself a condition of naturalism, is in fact incompatible with the deduction of genuinely explanatory/causal inferences. This suggests that the status of rational choice as an explanatory/predictive theory needs to be reassessed. Yet this is no reason to reject rational choice out of hand. For, deployed not as a theory in its own right, but as a heuristic analytical strategy for exploring hypothetical scenarios, it is a potent and powerful resource in post‐positivist public administration.