Flat Friedmann cosmologies with stiff fluid in Einstein–Cartan theory

Flat Friedmann cosmologies with stiff fluid are considered in the framework of the Einstein–Cartan theory. The version of this theory which simultaneously takes into consideration two sources of torsion, namely, a perfect fluid with the vacuum equation of state and a nonminimally coupled scalar field, is studied. It is demonstrated that, for bouncing models, phantom cosmologies with and without a Big Rip singularity are possible. Singular expanding models are presented where the early stages are dominated by a scalar-torsion field which behaves as an ultrastiff fluid, while the late stages are dominated by a perfect fluid which causes a de Sitter asymptotic. Some cosmological consequences of two sources of torsion are discussed.     

Regularities of thermoacoustic oscillations in Lehmann’s plant with a coolant moving in reverse

An approximate method is developed for calculating the instability boundaries, as well as the frequencies and amplitudes, of acoolant’s autooscillations self-excited during its motion in a vertical channel exposed to locally applied heat from a constant power source. Unlike in the classical generators of thermoacoustic oscillations such as the Rijke tube and Lehmann’s plant, it is assumed that the main stationary flow is collinear with the gravity force. In order to exclude the surging nature of the self-oscillations, it is assumed that the flow is created by a supercharger with a monotonically decreasing head-capacity characteristic. The resulting mathematical model makes it possible to theoretically determine the self-excitation conditions of the considered autooscillations and also to evaluate the effect of various parameters on their shape.     

An analysis of a firm’s capacity in Mazda’s Keiretsu

Capacity is defined as the power resulting from the specific position of a company in a network organization. This article extends the theory of network organizations to examine Mazda’s Yokokai Keiretsu, and proposes a new approach to calculating a firm’s capacity in a network. Capacity is divided into two categories, take-in capacity and take-out capacity, and the gap between them is called the capacity difference. We analyze the impact of capacity difference as a determinant of corporate performance in network organizations, thus providing a new perspective for successful corporate management.     

Using technology to encourage a healthier lifestyle in people with Down’s syndrome

Universal Access in the Information Society - This article reports on the development of a mobile app developed to encourage healthier lifestyles, with emphasis on food intake, by people with...     

Exact solution for a nonstatic cylindrically symmetric perfect fluid distribution in Einstein–Cartan theory

We consider a nonstatic, spin-polarized cylindrically symmetric perfect fluid distribution in the Einstein-Cartan theory and obtain the field equations. These field equations are solved using the Ray–Smalley energy-momentum tensor.     

Facilitator’s Roles in a Videoconference Learning Environment

The paper reports a study of a videoconference-based environment in decentralized university education and factors contributing to the success of teaching and learning in the environment. The focus of the paper is on the role of a person having the formal responsibilities of a technician. An ethnographic study conducted over the course of a year revealed that the contribution of this person far exceeded the scope of formal responsibilities. The person, who was acting in the setting as a facilitator, was found to possess expertise, which was critically important for supporting interaction between remote participants at several levels, such as attention management, time management, acquisition of setting-specific skills, and coordination within a larger institutional context. The findings suggest that supra-situational activities can be important factors for the successful functioning and development of emerging learning environments.This revised version was published online in March 2005 with corrections to the cover date     

An institutional theory perspective on e-HRM’s strategic potential in MNC subsidiaries

This paper extends the application of institutional theory to electronic human resource management (e-HRM), and strategic information systems (IS) more generally, in a multinational corporation (MNC) subsidiary setting. By adopting Scott’s (2001) institutional theory perspective, this paper explores the effects of host-country institutional factors on strategic e-HRM practices in foreign subsidiaries. More specifically, the aims of this paper were, first, to shed light on how regulative, cognitive and normative institutional dimensions affect Western-based e-HRM practices in MNC subsidiaries in China, and second, to examine how these institutional factors influence the strategic potential of e-HRM in this setting. Based on interview data collected from key informants in 10 MNC subsidiaries from Beijing and Shanghai, the findings illustrate how institutional pressures create both positive transformational and negative dysfunctional consequences for subsidiaries, and that subsidiary responses to these pressures can substantially affect the ability of IS to achieve its strategic potential. Although observed local adaptations were seen to restrict the strategic potential of IS, in some cases responses seem to have enabled the transposition of a new set of strategic IS practices to this non-Western setting.     

On the allowance for support costs in Prager-Rozvany’s optimal layout theory

A recent study by Rozvany and Sokó? (Struct Multidisc Optim, 2012) discussed an important topic in structural design: the allowance for support costs in layout optimization. Herein a frequently used kind of support will be examined, that of simple foundation with horizontal reaction by friction. This support does not seem to be covered by Authors’ approach. To illustrate this case some solutions obtained by standard design rules are included.     

Perspectives on management theory’s application in the internet of things research

Information Systems and e-Business Management - The growing use of the internet of things (IoT) has provided businesses with a new opportunity. This study performed a systematic literature review...     

Motion of a disk in contact with a parametric 2D curve and Painlevé’s paradox

Multibody System Dynamics - This paper addresses the modeling and simulation of a homogeneous disk that undergoes plane motion constrained to be in permanent contact with and in the same plane as a...     

Simulation of a mannequin’s thermal plume in a small room

Simulation results are presented for the buoyancy-driven flow in a small room containing a seated mannequin that is maintained at a constant temperature. The study was motivated, in part, by a published experimental study of the thermal plume around a human subject. The results presented are a step toward the goal of using DNS to develop a more detailed understanding of the nature of the flow in the thermal plume created by humans modeled here as heated mannequins. The results were obtained without using sub-grid scale modeling and are helpful in establishing the resolution requirements for accurate simulations. It is seen that the results for the highest resolution grid are in reasonable quantitative agreement with a published experimental study of a human subject’s thermal plume. The results for the velocity field are used to compute the trajectories of small particles in the room. Results are presented for the trajectories of five-micrometer solid particles that are initially dispersed near the floor in front of the mannequin. The simulation results show that the buoyancy-driven flow around the mannequin is effective at dispersing the particles over a large portion of the room.     

Atanassov’s intuitionistic fuzzy submodules with respect to a t-norm

In this paper, t-norm based intuitionistic fuzzy submodules are defined, and their various properties are investigated. We also show that if an intuitionistic fuzzy set of a module is an intuitionistic fuzzy submodule with respect to a t-norm, then it is also an intuitionistic fuzzy submodule with respect to the annihilation t-norm. We investigate the nature of intuitionistic fuzzy submodules of a module with the help of their respective cut sets. We obtain some results based on (α, β)-level sets and t-norm based α-cut sets of an intuitionistic fuzzy submodule with respect to a t-norm T.     

StoryCube: supporting children’s storytelling with a tangible tool

Storytelling is one of the effective methods used in education. Computer-aided storytelling allows children to create more free-form stories and provides a large amount of story materials. Grounded in the current related works, we design a tangible interactive tool, which supports children to interact with virtual objects via a tangible way instead of the usage of mouse/keyboard. With this tool, we also develop a storytelling system called StoryCube where children are able to create a 3D story environment and accomplish story narrations through physical manipulations to different virtual characters. From a preliminary user study, we find StoryCube full of playfulness, easy to learn and use, and somehow inspire children in storytelling activities.     

Jeffrey’s rule of conditioning in a possibilistic framework

Conditioning, belief update and revision are important tasks for designing intelligent systems. Possibility theory is among the powerful uncertainty theories particularly suitable for representing and reasoning with uncertain and incomplete information. This paper addresses an important issue related to the possibilistic counterparts of Jeffrey’s rule of conditioning. More precisely, it addresses the existence and uniqueness of the solutions computed using the possibilistic counterparts of the so-called kinematics properties underlying Jeffrey’s rule of conditioning. We first point out that like the probabilistic framework, in the quantitative possibilistic setting, there exists a unique solution for revising a possibility distribution given the uncertainty bearing on a set of exhaustive and mutually exclusive events. However, in the qualitative possibilistic framework, the situation is different. In particular, the application of Jeffrey’s rule of conditioning does not guarantee the existence of a solution. We provide precise conditions where the uniqueness of the revised possibility distribution exists.     

Solving Kirkman’s Schoolgirl Problem in a Few Seconds

The Social Golfer Problem has been extensively used by the constraint community in recent years as an example of a highly symmetric problem. It is an excellent problem for benchmarking symmetry breaking mechanisms such as SBDS or SBDD and for demonstrating the importance of the choice of the right model for one problem. We address in this paper a specific instance of the Golfer Problem well known as Kirkmans Schoolgirl Problem and list a collection of techniques and tricks to find efficiently all its unique solutions. In particular, we propose SBDD+, a generic improvement over SBDD which allows a deep pruning when a symmetry is detected during the search. Our implementation of the presented techniques improves previously published results by an order of magnitude for CPU time as well as for number of backtracks. It computes the seven unique solutions of Kirkmans problem in a few seconds.     

Coupling of optimal variation of parameters method with Adomian’s polynomials for nonlinear equations representing fluid flow in different geometries

In this study, we describe a modified analytical algorithm for the resolution of nonlinear differential equations by the variation of parameters method (VPM). Our approach, including auxiliary parameter and auxiliary linear differential operator, provides a computational advantage for the convergence of approximate solutions for nonlinear boundary value problems. We consume all of the boundary conditions to establish an integral equation before constructing an iterative algorithm to compute the solution components for an approximate solution. Thus, we establish a modified iterative algorithm for computing successive solution components that does not contain undetermined coefficients, whereas most previous iterative algorithm does incorporate undetermined coefficients. The present algorithm also avoid to compute the multiple roots of nonlinear algebraic equations for undetermined coefficients, whereas VPM required to complete calculation of solution by computing roots of undetermined coefficients. Furthermore, a simple way is considered for obtaining an optimal value of an auxiliary parameter via minimizing the residual error over the domain of problem. Graphical and numerical results reconfirm the accuracy and efficiency of developed algorithm.

     

T-test based Alzheimer’s disease diagnosis with multi-feature in MRIs

Multimedia Tools and Applications - Diagnosing Alzheimer’s disease (AD) with magnetic resonance imaging (MRI) has attracted increasing attention. In this paper, we propose a new feature...     

Living in a bubble? Toward a unified bubble theory

We generalise the notion of a bubble beyond the financial domain, by showing how a single social mechanism, based on an information feedback-loop, explains both financial bubbles and other seemingly disparate social phenomena, such as the recognition of academic articles, website popularity, and the spread of rumours.

We discuss examples of phenomena explained by this bubble mechanism, as well as other phenomena that exhibit certain bubble characteristics, yet are not bubbles according to our model. Finally, we present mathematical mechanisms for two phenomena that conform with our model, and show by computer simulation how they exhibit bubble behaviour.     

Is the cutoff radius in DPD simulations with a fluid of constant density arbitrary?

The DPD (Dissipative Particle Dynamics) method was used to simulate the flow of a fluid occupying the space inside a rotating infinite long cylinder. The fluid was initially at rest and rigid body rotation was expected to be reached. However, as the simulation proceeded, the DP?s (Dissipative Particles) began accumulating near the wall, leaving the cylinder?s core empty of DP?s, obviously, an aphysical solution. To solve this problem it was suggested to set the cutoff radius as a function of the DP?s number density. A conceptual explanation is suggested.