Indentation of power law creep solids by self-similar indenters

For creep solids obeying the power law under tension proposed by Tabor, namely sigma = b(epsilon) over dot(m), it has been established through dimensional analysis that for self-similar indenters the load F versus indentation depth h can be expressed as F(t) = bh(2)(t)[(h) over dot(t)/h(t)](m)Pi(alpha) where the dimensionless factor Pi(alpha) depends on material parameters such as m and the indenter geometry. In this article, we show that by generalizing the Tabor power law to the general three dimensional case on the basis of isotropy, this factor can be calculated so that indentation test can be used to determine the material parameters b and m appearing in the original power law. Hence indentation test can replace tension test. This could be a distinct advantage for materials that come in the form of thin films, coatings or otherwise available only in small amounts. To facilitate application values of this constant are given in tabulated form for a range of material parameters. (C) 2010 Elsevier B.V. All rights reserved.

HIRFL-CSR二极磁铁电源的研制；Development of Power Supply for HIRFL-CSR Dipole Magnet

研制了兰州重离子加速器冷却储存环(HIRFL-CSR)二极磁铁电源,提出了一种基于晶闸管相控整流技术和IGBT脉宽调制(PWM)变换技术的同步加速器二极磁铁电源的设计方案,分析、仿真了其工作原理,并设计、生产了1套完整的电源样机。经现场试验、长期运行及测试,电流稳定度<±5×10-5/8h,跟踪精度<±2×10-4,电流纹波<1×10-5。该方案满足HIRFL-CSR二极磁铁对电源技术指标的要求。

Sulfonated poly(ether ether ketone)/clay-SO3H hybrid proton exchange membranes for direct methanol fuel cells Journal of Power Sources

A new type of sulfonated clay (clay-SO3H) was prepared by the ion exchange method with the sulfanilic acid as the surfactant agent. The grafted amount of sulfanilic acid in clay-SO3H was 51.8 mequiv. (100 g)(-1), which was measured by thermogravimetric analysis (TGA). Sulfonated poly(ether ether ketone) (SPEEK)/clay-SO3H hybrid membranes which composed of SPEEK and different weight contents of clay-SO3H, were prepared by a solution casting and evaporation method. For comparison, the SPEEK/clay hybrid membranes were produced with the same method.

Exploring the Origin of Power Law Distribution in Single-Molecule Conformation Dynamics: Energy Landscape Perspectives

We explored the origin of power law distribution observed in single-molecule conformational dynamics experiments. By establishing a kinetic master equation approach to study statistically the microscopic state dynamics, we show that the underlying landscape with exponentially distributed density of states leads to power law distribution of kinetics. The exponential density of states emerges when the system becomes glassy and landscape becomes rough with significant trapping.

Between Anarchy and Society: Trusteeship and the Obligations of Power

Bain, William, Between Anarchy and Society: Trusteeship and the Obligations of Power (Oxford: Oxford University Press, 2003), pp.viii+216 RAE2008

France and the Problems of Security and Disarmament after the First World War

Jackson, Peter, 'France and the Problems of Security and Disarmament after the First World War', Journal of Strategic Studies (2006) 29(2) pp.247-280 Special Issue: Enforcing arms limits: Germany post 1919; Iraq post 1991 RAE2008

Why Ideas Matter in International Relations : Hans Morgenthau, Classical Realism, and the Moral Construction of Power Politics

Williams, Mike, 'Why ideas matter in International Relations: Hans Morgenthau, Classical Realism, and the Moral Construction of Power Politics', International Organization (2004) 58(4) pp.633-665 RAE2008

Through the Wire: Relations of Power and Relations of Violence

Edkins, J. and Pin-Fat, V. (2005). Through the Wire: Relations of Power and Relations of Violence. Millennium - Journal of International Studies. 34(1), pp.1-24 RAE2008

On the Origin of Power Laws in Internet Topologies

Recent empirical studies have shown that Internet topologies exhibit power laws of the form for the following relationships: (P1) outdegree of node (domain or router) versus rank; (P2) number of nodes versus outdegree; (P3) number of node pairs y = x^α within a neighborhood versus neighborhood size (in hops); and (P4) eigenvalues of the adjacency matrix versus rank. However, causes for the appearance of such power laws have not been convincingly given. In this paper, we examine four factors in the formation of Internet topologies. These factors are (F1) preferential connectivity of a new node to existing nodes; (F2) incremental growth of the network; (F3) distribution of nodes in space; and (F4) locality of edge connections. In synthetically generated network topologies, we study the relevance of each factor in causing the aforementioned power laws as well as other properties, namely diameter, average path length and clustering coefficient. Different kinds of network topologies are generated: (T1) topologies generated using our parametrized generator, we call BRITE; (T2) random topologies generated using the well-known Waxman model; (T3) Transit-Stub topologies generated using GT-ITM tool; and (T4) regular grid topologies. We observe that some generated topologies may not obey power laws P1 and P2. Thus, the existence of these power laws can be used to validate the accuracy of a given tool in generating representative Internet topologies. Power laws P3 and P4 were observed in nearly all considered topologies, but different topologies showed different values of the power exponent α. Thus, while the presence of power laws P3 and P4 do not give strong evidence for the representativeness of a generated topology, the value of α in P3 and P4 can be used as a litmus test for the representativeness of a generated topology. We also find that factors F1 and F2 are the key contributors in our study which provide the resemblance of our generated topologies to that of the Internet.

Investment incentives and valuation of power sector infrastructure assets with increasing interconnection, intermittency and decarbonisation

This dissertation applies a variety of quantitative methods to electricity and carbon market data, utility company accounts data, capital and operating costs to analyse some of the challenges associated with investment in energy assets. In particular, three distinct research topics are analysed within this general theme: the efficiency of interconnector trading, the optimal sizing of intermittent wind facilities and the impact of carbon pricing on the cost of capital for investors are researched in successive sections.

Popular culture, relational history, and the question of power in Palestine and Israel

The marginalization of popular culture in radical scholarship on Palestine and Israel is symptomatic of the conceptual limits that still define much Middle East studies scholarship: namely, the prevailing logic of the nation-state on the one hand and the analytic tools of classical Marxist historiography and political economy on the other. This essay offers a polemic about the form that alternative scholarly projects might take through recourse to questions of popular culture. The authors argue that close allention to the ways that popular culture "articulates" with broader political, social, and economic processes can expand scholarly understandings of the terrain of power in Palestine and Israel, and hence the possible arenas and modalities of struggle. © 2004 by the Institute for Palestine Studies. All rights reserved.

Thermo-mechanical modelling of power electronics module structures

Power electronic modules distinguish themselves from other modules by their high power operation. These modules are used extensively in high power application markets such as aerospace, automotive, industrial and traction and drives. This paper discusses typical packaging technologies for power electronics modules. It also discusses the latest results from a UK research project investigating the physics-of-failure approach to reliability analysis and predictions for power modules. An integrated design enviroment for incorporating of affects of uncertainty into the design environment was outlined.

Thermal-mechanical modelling of power electronic module packaging

In this paper the reliability of the isolation substrate and chip mountdown solder interconnect of power modules under thermal-mechanical loading has been analysed using a numerical modelling approach. The damage indicators such as the peel stress and the accumulated plastic work density in solder interconnect are calculated for a range of geometrical design parameters, and the effects of these parameters on the reliability are studied by using a combination of the finite element analysis (FEA) method and optimisation techniques. The sensitivities of the reliability of the isolation substrate and solder interconnect to the changes of the design parameters are obtained and optimal designs are studied using response surface approximation and gradient optimization method