Model Validation and Performance Evaluation for The Multi-Tethered Aerostat Subsystem of the Large Adaptive Reflector

The Canadian design for the Square Kilometre Array radio telescope includes a large multi-tethered aerostat to support the telescope’s receiver. To validate this design concept, two parallel tracks have been undertaken: a numerical simulation of the multi-tethered aerostat system has been assembled, and a one-third scale prototype of the system has been constructed. This paper describes the experimental facility, presents results from initial tests of the uncontrolled system and compares these results to the predictions of the computer model of the system. Generally, the results compare very favourably. Using the simulation, we arrive at two important design philosophies to be used in the design of the full-scale system: (a) perturbations on the confluence point should be minimized, and (b) the system stiffness should be maximized to ensure minimum response to disturbances.     

Community, difference and identity: the case of the Irish in Sheffield

There is a growing body of research in racial and ethnic studies on the processes of identity construction within minority ethnic populations. This article seeks to build on this work by analysing emerging collective identity formations in an ‘invisible’ minority ethnic group. Based upon focus groups and in-depth interviews with Irish people in Sheffield, the article aims to advance three key arguments. First, the concept of community is central to an Irish collective identity, but is negotiated in a multiplicity of ways. Second, Irish collective identity has been shaped not only by demographic differences but by shared experiences of non-recognition and stereotyping. Third, there is a simultaneous assertion of an Irish identity running parallel with a perception that the ‘traditional’ Irish community may have to re-invent itself in response to changing demographics at the local level. The paper concludes by considering the implications of these arguments for an understanding of Irish ethnicity in multicultural Britain.     

Evaluation of fibre rope properties for offshore mooring

An examination has been conducted of fibre rope mechanical properties measured in laboratory tests on materials, constructions and terminations intended for deepwater mooring applications. This data, combined with field experience, provide a better understanding of rope behaviour and enhances the knowledge required to engineer fibre ropes for these demanding applications.This has also led to improved laboratory test techniques for measurement of mechanical properties relevant to mooring system response analyses required to meet regulatory requirements. Preliminary evaluation of the data also indicates that a post-test evaluation method to determine retained properties of insert strops removed from mooring lines may be possible.     

东太平洋洋隆Siqueiros转换断层带的地球化学特征

东太平洋洋隆Siqueiros转换断层带(西经103°~104°、北纬8°20′~8°30′),位于中美洲之西可可斯板块与太平洋板块交接处(图1).该转换断层的玄武岩,成分从原始的到富化的,变化很大.最原始的玄武岩产于A-B走滑断层内,其MgO含量高达14.91%;最富化的玄武岩产在西部洋脊与转换断层交叉部位,其MgO含量较低,成分变化大.转换断层内的洋中脊玄武岩可分三类:富化的洋脊玄武岩(E-MORB)、原始的正常洋脊玄武岩(Primitive N-MORB)和正常洋脊玄武岩(N-MORB).Siqueiros转换断层区已确定有两个地幔源:一个位于转换断层西部下面的富集地幔,其特点是稀土总量高,富轻稀土,低MgO、K2O和TiO2,而高87Sr/86Sr;另一个是位于转换断层中-东部下面的亏损地幔,来自这个地幔源的玄武岩具有低87Sr/86Sr、低稀土元素和微量元素含量,但MgO含量较高.     

Permeability of JSC-1A: A lunar soil simulant

The permeability of lunar soil simulant, JSC-1A, is measured over a range of bulk densities from 1550 to 2000 kg m⁻³. The corresponding viscous flow permeability is 1 × 10⁻¹² m² to 6.1 × 10⁻¹² m² for this bulk density range. Implications of these values on the contamination of regolith by rockets, on barrier/enhancement to bulk flow of ice, and on cratering are discussed. Although the particle size and shape distribution of the JSC-1A are extremely wide, the permeability measurements agree surprisingly well with the Carman-Kozeny equation. The results provide evidence that the Carman-Kozeny model could be applicable to other naturally occurring soils if effective soil properties are considered.