Shear strain properties to 10 sup -10 of selected optical materials

Plastic deformation of corrosion resistant steel, CER-VIT 101, and fused silica as function of applied torsional stres

Organisational change and development of reformed Chinese township and village enterprises

This article is (c) Emerald Group Publishing and permission has been granted for this version to appear here (http://bura.brunel.ac.uk/handle/2438/8263). Emerald does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Emerald Group Publishing Limited.Purpose – This paper aims to investigate the organisational changes (OCs) and the development of Chinese reformed township and village enterprises (RTVEs), their marketing and R&D strategies, and the impact of changes in terms of overall performance. Design/methodology/approach – A case study methodology involving semi-structured interviews is adopted. The unit chosen is the Guotai International Group (GTIG) in Zhangjiagang, Suzhou, Jiangsu province, China, in which the organisational changes over a period of over 40 years are analysed. Findings – OCs in Chinese RTVEs are found to be driven by a combination of local government plans and market forces. Considering the hybrid nature of the organisation and ownership structures, changes in Chinese RTVEs follow a very much “top-down” approach. Research limitations/implications – The findings imply that managers appointed by the state in RTVEs usually lack the necessary skills in marketing and business management, and can be resistant to organisational changes, such as the willingness to undertake risks. As a result, RTVEs may become stuck in a cycle of low-cost, low-tech products, inhibiting any breakthrough in developing their own quality brands. Originality/value – This is one of few papers studying change over a long span of time to arrive at research findings that will be useful to academic researchers in their future work. The qualitative findings from this paper would also enrich the literatures on organisational change in Chinese RTVEs

On the thermal buffering of naturally ventilated buildings through internal thermal mass

In this paper we examine the role of thermal mass in buffering the interior temperature of a naturally ventilated building from the diurnal fluctuations in the environment. First, we show that the effective thermal mass which is in good thermal contact with the air is limited by the diffusion distance into the thermal mass over one diurnal temperature cycle. We also show that this effective thermal mass may be modelled as an isothermal mass. Temperature fluctuations in the effective thermal mass are attenuated and phase-shifted from those of the interior air, and therefore heat is exchanged with the interior air. The evolution of the interior air temperature is then controlled by the relative magnitudes of (i) the time for the heat exchange between the effective thermal mass and the air; (ii) the time for the natural ventilation to replace the air in the space with air from the environment; and (iii) the period of the diurnal oscillations of the environment. Through analysis and numerical solution of the governing equations, we characterize a number of different limiting cases. If the ventilation rate is very small, then the thermal mass buffers the interior air temperature from fluctuations in the environment, creating a near-isothermal interior. If the ventilation rate increases, so that there are many air changes over the course of a day, but if there is little heat exchange between the thermal mass and interior air, then the interior air temperature locks on to the environment temperature. If there is rapid thermal equilibration of the thermal mass and interior air, and a high ventilation rate, then both the thermal mass and the interior air temperatures lock on to the environment temperature. However, in many buildings, the more usual case is that in which the time for thermal equilibration is comparable to the period of diurnal fluctuations, and in which ventilation rates are moderate. In this case, the fluctuations of the temperature of the thermal mass lag those of the interior air, which in turn lag those of the environment. We consider the implications of these results for the use of thermal mass in naturally ventilated buildings

Investigation of real-gas and viscous effects on the aerodynamic characteristics of a 40 deg half-cone with suggested correlations for the shuttle orbiter

Parameters were evaluated that might be used to correlate shuttle orbiter aerodynamic data to be used in extrapolating from wind-tunnel to flight conditions. Preliminary calculations indicate that the lee-side forces will have an insignificant influence on the aerodynamic characteristics of the orbiter for moderate angle-of-attack entries; therefore, this work is focused on phenomena which have an overriding influence on windward forces, namely, real-gas (equilibrium and nonequilibrium) and viscous-interaction effects. Analytically determined flow fields previously obtained on 40 deg blunted cones were used as a data source to evaluate various correlation parameters. Inviscid effects were found to be the dominant contributor to the aerodynamic coefficients in the altitude range of 64 to 76.2 km. The most suitable correlation of the aerodynamic forces on these cones is based on local dynamic pressure and local Mach number

On the extraction of gas from multilayered rock

his paper presents some simple analytical and numerical models which describe the dynamics of gas flowing from a multilayered low-permeability porous rock into a fracture. The models account for the vertical flow between relatively high- and low-permeability layers. The motion of gas in a permeable rock is governed by a nonlinear diffusion equation for the gas pressure. We analyse the gas flow described by this equation in both bounded and unbounded domains. In both cases simple scalings laws are developed to determine the fluxes and the dimensions of the regions within the rock which may be depleted over a given time scale. These are compared with the results of a full numerical model

Metabolic Effects of Bariatric Surgery in Mouse Models of Circadian Disruption

Background/Objectives: Mounting evidence supports a link between circadian disruption and metabolic disease. Humans with circadian disruption (for example, night-shift workers) have an increased risk of obesity and cardiometabolic diseases compared with the non-disrupted population. However, it is unclear whether the obesity and obesity-related disorders associated with circadian disruption respond to therapeutic treatments as well as individuals with other types of obesity. Subjects/Methods: Here, we test the effectiveness of the commonly used bariatric surgical procedure, Vertical Sleeve Gastrectomy (VSG), in mouse models of genetic and environmental circadian disruption. Results: VSG led to a reduction in body weight and fat mass in both ClockΔ19 mutant and constant-light mouse models (PP\u3e0.05). Within circadian-disrupted models, VSG also led to improved glucose tolerance and lipid handling (P\u3c0.05). Conclusions: Together these data demonstrate that VSG is an effective treatment for the obesity associated with circadian disruption, and that the potent effects of bariatric surgery are orthogonal to circadian biology. However, as the effects of bariatric surgery are independent of circadian disruption, VSG cannot be considered a cure for circadian disruption. These data have important implications for circadian-disrupted obese patients. Moreover, these results reveal new information about the metabolic pathways governing the effects of bariatric surgery as well as of circadian disruption

Experiments on standing bubbles in a vertical pipe

We present a series of laboratory experiments in which a steady stream of air is supplied through a small hole in the wall of a vertical pipe of rectangular cross-section down which there is a steady flux of water. For a range of liquid flow rates, the air forms a steady standing bubble whose nose is attached to the point of air supply. The steady bubble sheds a flux of much smaller air bubbles at its base, located downstream of the air injection point. The minimum liquid speed for which steady standing bubbles develop occurs at a particular Froude number of the liquid flow, Frd = U/$/sqrt{\it gd}$ = 0.38, where U is the upstream speed, g the acceleration due to gravity and d the width of the cell. These trapped bubbles are distinct from the freely rising Taylor bubble, in that the Froude number at the nose is variable. Also, on a length scale greater than that influenced by surface tension, we find that the bubble nose asymptotes to a cusp-like shape, with an angle that decreases with Frd. We show that numerical solutions of the potential flow equations replicate the bubble shape and angle of the cusp, which appear independent of the gas flux. We also find that there is a minimum gas flux for which these standing bubbles develop. As the gas flux decreases below this threshold, the standing bubbles become unstable and, instead, a much shorter oscillating bubble develops. This produces a wake which has similarities with that formed downstream of a cylinder in a confined channel, but which also carries bubbles downstream. We also find that with sufficiently small gas flux, no bubble develops. For liquid flow rates smaller than the critical value, Frd < 0.38, we find that the bubbles become unstable and detach from the injection point and rise up the tube

Natural ventilation of multiple storey buildings: The use of stacks for secondary ventilation

The natural ventilation of buildings may be enhanced by the use of stacks. As well as increasing the buoyancy pressure available\ud to drive a flow, the stacks may also be used to drive ventilation in floors where there is little heat load. This is achieved by connecting\ud the floor with a relatively low heat load to a floor with a higher heat load through a common stack. The warm air expelled from the\ud warmer space into the stack thereby drives a flow through the floor with no heat load. This principle of ventilation has been adopted\ud in the basement archive library of the new SSEES building at UCL. In this paper a series of laboratory experiments and supporting\ud quantitative models are used to investigate such secondary ventilation of a low level floor driven by a heat source in a higher level\ud floor. The magnitude of the secondary ventilation within the lower floor is shown to increase with the ratio of the size of the\ud openings on the lower to the upper floor and also the height of the stack. The results also indicate that the secondary ventilation\ud leads to a reduction in the magnitude of the ventilation through the upper floor, especially if the lower floor has a large inlet area.\ud r 2005 Elsevier Ltd. All rights reserve