Crystal Structures and Magnetic Properties of the Co2Mn1−x V x Sb (0 ≤ x ≤ 1) Heusler Compounds

Crystal structure and magnetic properties of the Co₂Mn_1?x V _x Sb (0 ≤ x ≤ 1) Heusler compounds have been studied by X-ray powder diffraction (XRD), magnetometric measurements, and full-potential linearized augmented plane wave (FP–LAPW) method. All compounds crystallize in a cubic Cu₂MnAl-type crystal structure with the space group Fm–3m. The samples for x<0.8 have the Curie temperatures above room temperature, while the Curie temperature is observed at 68 K for the sample with x = 0.8. The saturation magnetization at 5 K decreases linearly with increasing vanadium concentration x. The values of the saturation magnetization obtained by FP–LAPW–local density approximation (LDA) calculations are in better agreement with the experimental results compared with the results obtained by FP–LAPW–generalized gradient approximation (GGA) calculations.     

Multi-Criteria Query Optimization in the Presence of Result Size and Quality Tradeoffs

In this paper, we present novel multi-criteria query optimization techniques for performing query optimization in databases, such as multimedia and web databases, which rely on imperfect access mechanisms and top-k predicates. We present an optimization model that (1) takes into account different binding patterns associated with query predicates, (2) considers the variations in the expected query result sizes as a function of query execution plans, and (3) considers the expected result qualities of the execution orders. We address the complexity and the well-known NP-complete nature of the query optimization problem by adaptively reducing the granularity of the search space. For this purpose, unlike the data histograms which capture the data distribution, we propose opt-histograms that capture the distribution of sub-query-plan values over many optimization tasks.     

Minimum component SRCO and VFO using a single DVCCC

Two oscillator topologies each employing a single differential voltage complementary current conveyor (DVCCC) are presented. The first oscillator uses a single active element, five passive components, grounded capacitors, has independent control of frequency and condition of oscillation. It has a current mode output and can be extended to provide a voltage mode output. It combines all the features of the current state-of-art oscillators. The second oscillator uses a single DVCCC, four passive elements, grounded capacitors and provides independent control of frequency. This oscillator not only has all the desired oscillator features, but requires lesser passive components. Theoretical analysis of these oscillators was verified with SPICE simulations.     

Similarity-Based Retrieval of Temporal Specifications and its Application to the Retrieval of Multimedia Documents

In this paper, we describe a similarity-based retrieval framework for temporal information, such as multimedia presentations. We develop techniques that allow users to query and retrieve multimedia documents, based on their temporal content. For this purpose, we describe different temporal data models and a set of similarity metrics applicable for different retrieval tasks. We develop algorithms that efficiently compute these metrics and report on experiment results. We also develop algorithms that efficiently index temporal structures based on these measures and show that the proposed variant of multi dimensional scaling is efficient and provides high quality retrieval of temporal specifications.     

A min—sum—max resource allocation problem

In this paper we describe a class of resource allocation problems with a min-sum-max objective function. We first discuss practical applications of the problem. We then present a result on the computational complexity of the problem. We propose an implicit enumeration procedure for solving the general case of the problem, and report on our computational experience with the solution procedure.     

Rigid-like fluid motion

Summary An arbitrary, rigid-like, unsteady flow of a fluid under constant, uniform body force is shown to be impossible in general unless the flow is a translation parallel to the body force. Consequently, the known steady-state, rigid-like fluid flows having horizontal components could be reached from a state of rest by the aid of dissipative processes only; and any two such steady states cannot be tied by an unsteady rigid-like flow program. Examples are given for approximately —rigid-like plane motion of a liquid under gravity, which are of practical significance from the view-point of transportation of liquids, as well as of large solid structures.     

Role models—implementation‐based approaches to using roles

A role of an entity can be defined as the set of properties that are important for an object in order to behave in a certain way, as expected by a set of other objects. A role model is a software that specifies a style of designing and implementing roles. This paper evaluates roles in the context of modeling dynamic systems by examining its foundations, surveying the recent role models available for academic use and giving implementation examples. Copyright © 2010 John Wiley & Sons, Ltd.     

The environmental effects of coal-related activities

The increase in population and industrial development leads to more consumption of coal. However, serious health effects and environmental problems are caused by coal. It releases toxic chemicals which are dangerous if released into the environment. Coal has indicated the capacity to meet such difficulties in the past and the view is that it will successfully meet future environmental difficulties. This study aims to relate the use of coal to the environmental concern that affects the society.     

Enhanced proton transport properties of Nafion via functionalized halloysite nanotubes

The introduction of naturally occurring fibrillary structured halloysite clays (HNTs) into the Nafion matrix resulted in an enhanced proton conductivity and a reduced activation energy for proton transport. To assess the effect of the various states of the HNTs as a membrane additive, the σ_H⁺ of the composite membranes (Nafion/HNTs, Nafion/HNTs-NH₂, Nafion/HNTs-SO₃H) was measured at 30 °C and 80 °C and at different levels of relative humidity (%RH). An overall improvement of the σ_H⁺ of the Nafion was observed in the presence of the nanotubular additives (HNTs or HNTs-NH₂) which can be attributed to the high specific surface area accommodating hydrophilic functional groups and therefore contributing to the water retention/management in the composite membrane. However, the Nafion/HNT-SO₃H composites are distinguished in terms of enhanced performance in σ_H⁺ which persist in the whole range of % RH levels and noted that the σ_H⁺ values are almost 2 times higher than native Nafion in the low humidity region (30%–50%) and at 80 °C. In agreement with the σ_H⁺ enhancement, the activation energy is lower than that of native Nafion indicating that the proton transport is facilitated in the presence of -SO₃H modified HNTs, probably due to an improved connectivity and arrangement of ionic conducting domains.