THE COURTYARD IN RURAL HOMESTEADS OF BANGLADESH

Abstract

In rural settlements of the floodplains in Bangladesh, an intrinsic element is the homestead. The homestead layout is defined by the courtyard, formed by the arrangement of dwelling units and ancillary buildings around a rectan- gular open space. The courtyard has important physical and functional characteristics derived from local climatic requirements and living patterns. However, particularly in this predominantly Muslim society, the cultural norm of maintaining women’s privacy is an important factor behind the development of this archetypal space. Nonetheless, other ethnic communities in the floodplains also often have courtyards, suggesting that it is a regional archetype. The archetypal courtyard is now subject to transformation due to social, economic and environmental changes. If this trend continues, it would signal the loss of an important and long-lasting regional expression that has resulted from the blending of culture, climate and nature.     

Thirtieth Anniversary of the Vernacular Architecture Group

Abstract

1984 has seen the thirtieth anniversary of the inaugural meeting of the V.A.G., which took place on 8 April 1954, as recorded by Sir Robert de Zouche Hall in VA 5, 1974. It was therefore thought appropriate to ask a number of people to offer their views on the achievements of the Group so far and on the direction which its work, and vernacular studies in general, should take in the future.

Cary Carson writes from the point of view of an overseas member; Christopher Currie contributes an historian's opinion; Linda Hall belongs to the younger generation of buildings researchers; Eric Mercer writes as one of the pioneers of vernacular studies in this country; John Newman presents an outsider's view of the material published in this journal, suggesting that the divide between 'vernacular' and 'polite' can be overemphasised and that the relationships which can be demonstrated in the seventeenth-century and later may be applicable to the study of the domestic architecture of earlier periods.     

Investigation of seal effects according to axial compression variation of metal seals for transport and storage casks

Abstract

Casks for the transport and storage of heat generating radioactive waste in Germany are normally provided with screwed lid systems, which are in most cases equipped with double jacket metal seals with an inner spring wire to provide long term resistance to the seal compression force. Preservation of the high sealing quality of those seals under operational and accidental stress conditions is essentially important to the safety of those casks. Relative displacements of the lid system surfaces caused by specific impact scenarios cannot be excluded and have to be evaluated with respect to a possible increase in the leakage rate.

To get representative data for such metal sealed lid systems, BAM has developed a special conceptualised flange system placed in an appropriate testing machine for relevant mechanical loading of the metal seals under static and cyclic conditions. Furthermore, the flange system enables continuous measurement of the standard helium leakage rate during each test.

The primary aim of the investigation is to identify the correlation between variation of installation conditions (axial displacements) caused by external loads and the standard helium leakage rate. An essential parameter in this case is the useable resilience r_u of a metal seal under relevant stress conditions. The useable resilience r_u is the vertical difference in the cross-section between the seal's assembling status and the point where the leakage rate, by means of external load relieving, exceeds the quality criterion of 10^–8 Pa m³ s^–1. Load relieving can instantly occur due to modification of the seal groove dimension caused by accident impacts and deformation of the lid system. Furthermore, component specific basis data for the development of finite element calculation models should be collected. In the tests, seals are subjected to static and cyclic loads. All tests are performed at ambient temperature.

This paper presents the test configuration, different test series and results of the current experiments. Typical load–displacement–leakage rate correlations are presented and discussed.     

Role of vacancies in coprecipitation of δ′ – and S–phasesin Al–Li–Cu–Mg alloys

Abstract

Precipitation reactions in a series of Al–Li–Cu–Mg alloys, encompassing the composition ranges of the commercial Lital A and Lital B materials, have been studied to determine the role of solute and vacancy concentrations on homogeneous S-phase (Al₂CuMg) precipitation. Homogeneous precipitation of S-phase only occurs when a critical combination of free vacancy and copper and magnesium supersaturation is achieved. Lithium reduces the free-vacancy concentration by strong binding between vacancies and lithium atoms or atom clusters. Precipitation of δ′ (Al₃ Li) releases the bound vacancies and thereby promotes S-phase formation and, in extreme cases, vacancy condensation, producing dislocation loops.

MST/350     

Lean Cr iron powders for obtaining high performance PM steel grades

Abstract

Ecological and economic demands are driving PM markets to incorporate less expensive, yet effective, alloying elements in iron based powders. To investigate their potential for this purpose recently developed sinter-hardening iron powders containing Cr and smaller amounts of Mo and Ni were industrially sintered at 1120 and at 1240°C under laboratory conditions. One set of samples, containing 0·8% graphite additions, was cooled so to obtain sinter-hardened steels. A second set of samples, containing 0·3% graphite, was cooled under normal conditions and subjected to a secondary carburising treatment. The microstructures and mechanical properties developed were compared.     

Nickel-based Gadolinium Alloy for Neutron Adsorption Application in Ram Packages

Abstract

The National Spent Nuclear Fuel Program, located at the Idaho National Laboratory (INL), coordinates and integrates national efforts in management and disposal of US Department of Energy (DOE)-owned spent nuclear fuel. These management functions include development of standardised systems for long-term disposal in the proposed Yucca Mountain repository. Nuclear criticality control measures are needed in these systems to avoid restrictive fissile loading limits because of the enrichment and total quantity of fissile material in some types of the DOE spent nuclear fuel. This need is being addressed by development of corrosion-resistant, neutron-absorbing structural alloys for nuclear criticality control. This paper outlines results of a metallurgical development programme that is investigating the alloying of gadolinium into a nickel–chromium–molybdenum alloy matrix. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutronabsorption cross section and low solubility in the expected repository environment. The nickel–chromium–molybdenum alloy family was chosen for its known corrosion performance, mechanical properties, and weldability. The workflow of this programme includes chemical composition definition, primary and secondary melting studies, ingot conversion processes, properties testing, and national consensus codes and standards work. The microstructural investigation of these alloys shows that the gadolinium addition is present in the alloy as a gadolinium-rich second phase. The mechanical strength values are similar to those expected for commercial Ni–Cr–Mo alloys. The alloys have been corrosion tested with acceptable results. The initial results of weldability tests have also been acceptable. Neutronic testing in a moderated critical array has generated favourable results. An American Society for Testing and Materials material specification has been issued for the alloy and a Code Case has been submitted to the American Society of Mechanical Engineers for code qualification.