Partitioning for selective assembly

Selective assembly is a means by which high-precision assemblies may be fabricated from relatively low precision components. This is accomplished by partitioning the component populations into groups prior to random assembly. This paper details an enhanced BASIC program that will generate group partitions given component distributions and the desired number of groups.     

A new approach to housing theory: Sex,gender and the domestic economy

Housing has to compete for resources with industrial and commercial capital. Beyond this economic dimension, large numbers of housing intellectuals and policymakers argue persuasively that housing has strong claims to fulfil basic social needs. Sometimes such arguments will be used to justify some provisions of subsidies to housing, though from the very nature of housing, it is seldom easy to establish common and agreed notions of ‘subsidy’ among the antagonists in the social needs debates. An issue which is very much related to this is whether housing should as a whole, and perhaps admitting some cross‐subsidisation, resource and finance its own capital and maintenance costs. Most of the inherently contentious debates on these issues are pursued within some general theory of political economy, with liberal‐capitalist and socialist‐radical versions in competition with each other. In this piece of writing an alternative theory and approach is presented. Essentially it begins from the assumption that housing is domestic capital (as distinct from industrial capital) which is economically productive, though its products are often consumed ‘at home’ rather than being marketed. This new theoretical approach completely alters perceptions on how economic resourcing and social needs can be linked. It has implications for the roles of women (and men) in our society, as well as forming a new contribution to the social economics of housing.     

Multifactorial analysis of lung cancer dose-response relationships for workers at the Mayak nuclear enterprise

Dose-response relationships for alpha-radiation-induced lung cancers (adenocarcinoma, squamous carcinoma and small cell carcinoma) were developed by multifactorial analysis using data for Mayak nuclear enterprise workers chronically exposed by inhalation to 239Pu. The three most important lung cancer risk factors (smoking, plutonium incorporation, and external gamma irradiation), out of six factors previously identified, were used. Relative risks (odds ratios) were determined for 500 nuclear enterprise workers (162 cancer cases, 338 control) for different dose levels using a case-control study design and logistic regression. A threshold at about 3.7 kBq or 0.80 Gy was discovered for incorporated plutonium, which is satisfactorily described by linear-quadratic and quadratic models. Excess relative risk was 0.020 kBq(-2) and 0.97 Gy(-2). This quadratic function was mainly due to adenocarcinoma. A trend for decreasing risk was noted for the lowest levels of plutonium incorporation, near permissible level. No clear-cut dose-response relationship for lung cancer induction by chronic external gamma irradiation was obtained. Lung cancer induction by cigarette smoking had a linear dependence: smoking of one pack of papiroses (a type of Russian cigarette) per day for 5 y increases the lung cancer risk twofold. The effect was most clearly manifested for squamous-cell carcinoma.     

Effect of increased afterload on cardiac lipoprotein lipase and VLDL receptor expression

Fatty acids are a major source of fuel for energy production by myocytes. Lipoprotein lipase (LPL) and very low density lipoprotein (VLDL) receptor are abundantly expressed by the heart and skeletal muscles. LPL and possibly VLDL receptor represent the primary route of access to fatty acids contained in circulating triglyceride-rich lipoproteins. Physical exercise and thyroid hormone, which promote energy consumption, upregulate LPL expression in skeletal muscles. This study tested the hypothesis that increased cardiac workload might modulate myocardial LPL and/or VLDL receptor expressions. Accordingly, cardiac tissue LPL activity, LPL and VLDL receptor proteins and mRNA abundance were studied in Sprague-Dawley rats 4 weeks after induction of severe thoracic aorta constriction or sham operation. Elevation of afterload with thoracic aortic constriction led to a significant cardiomegaly and a marked upregulation of cardiac LPL activity, LPL mRNA and LPL protein abundance, but did not modify VLDL receptor mRNA or protein abundance. Thus, increased cardiac workload in this model results in upregulation of myocardial LPL expression which can enhance fatty acid availability to accommodate the heart's increased energy requirement.     

Dynamic analysis of a crack-arrest specimen

Under pressurized thermal shock (PTS) loading conditions arrest of running cracks at temperatures that range up to or above those corresponding to the onset of Charpy upper shelf is of particular interest. Only few crack arrest toughness (K_Ia) data above 200 MPa√m obtained from rather expensive PTS-experiments and wide-plate tests are available. In the present paper the capabilities of a relatively small panel crack arrest specimen for yielding K_Ia data in excess of 200 MPa√m under conditions of a rising K_I-field are investigated. For this purpose static and dynamic finite element analyses are performed. It is shown that dynamic effects cannot be neglected for this specimen type and K_Ia-values up to about 300 MPa√m can be expected from measurements in suitably conducted experiments.     

Fracture toughness and water uptake of high-performance epoxy/nanoclay nanocomposites

Aircraft grade epoxy–clay nanocomposites based on tetraglycidyl-4, 4′-diaminodiphenylmethane (TGDDM) cured with diaminodiphenyl sulphone (DDS) were synthesized. Nanoclay was dispersed in both acetone and an acetone epoxy solution with a high pressure mixing (HPM) method to form pastes. The basal spacing of the nanoclay in these pastes was increased as observed from X-ray diffraction (XRD) data. Transmission electron microscopy (TEM) images show that the agglomerates of nanoclay were broken down to form small particles consisting of several clay platelets. Fracture toughness of this epoxy system has been greatly enhanced with the addition of nanoclay. With the addition of only 4.5 phr of clay, the strain energy release rate of the epoxy is increased 5.8 times from the original value. Scanning electron microscope (SEM) was used to examine the characteristics of the fracture surfaces from the different materials. There is also significant reduction in the diffusivity and the maximum water uptake of the epoxy resin with the addition of the nanoclay.     

Synthetic neural networks for process control

Synthetic neural networks offer great promise for process control. A performance comparison is drawn between traditional statistical process control methods and neural networks. Specifically, a series of simulation experiments in which back propagation networks are contrasted with control charts is described. The basis for comparison is average run length (both predicted and observed) and accuracy. The Monte Carlo simulations are derived from plausible production process data. Neural networks were found to perform reasonably well under most conditions.     

Urbanization in developing countries: an overview of the economic and policy issues in the 1990s.

Cedric Pugh argues that past efforts to tackle rapid urbanization and its related problems and constraints have been inadequate, and that the rate and scale of likely urbanization over the next couple of decades pose challenges which require very different and innovative approaches. The bulk of his paper describes the evolution of policy over the past 30 years within the World Bank, the International Monetary Fund, the UN Development Program, and the UN Center for Human Settlements, the leading international lending and development agencies concerned with Third World economic and urban policy issues. Pugh argues that these institutions have learned much from their own experience and that far more flexible and realistic policy changes have been adopted since the late 1980s. They move away from orthodox neoliberalism and give greater attention to social programs, and emphasize public-private partnerships and the creation of an enabling environment rather than direct state involvement. Pugh criticizes a considerable number of academic writers for being unduly ideologically driven in advocating statism along socialist lines or a quasi-Western welfare state. He declares himself an advocate of the New Political Economy, discusses this school of thought, and considers experiences in the Asian NICs, Mexico, Sri Lanka, and Tanzania.