Rapid Design and Manufacture of Ultralight Cellular Materials

This paper details the design, manufacture and testing of regular metallic lattice structures with unit cell sizes in the range 0.8mm to 5mm and truss elements of 100-500 µm in diameter [1]. The structures were manufactured using Selective Laser Melting (SLM) technology from 316L stainless steel. Compression tests have shown yield loadings of over 3.5kN despite being only 18mm by 18mm by 10mm in height, the results are favourably comparable to current commercially available metallic foams. Software has been developed that creates slice files without the use of CAD software or STL files and is capable of producing lattices within a volume defined by a STL file.Mechanical Engineerin

Cultures of caste and rural development in the social network of a south Indian village

Cultures of caste in much of rural India have become entangled with institutions of rural development. In community-driven development, emphasis on “local resource persons” and “community spokespersons” has created new opportunities for brokerage and patronage within some villages, which interact with existing forms of authority and community afforded by caste identity and intra-caste headmanship. In this article, we study how these entangled cultures of caste and development translate into social network structures using data on friendship ties from a south Indian village. We find that although caste continues to be important in shaping community structures and leadership in the village’s network, its influence varies across different communities. This fluidity of caste’s influence on community network structures is argued to be the result of multiple distinct yet partially overlapping cultural-political forces, which include sharedness afforded by caste identity and new forms of difference and inequality effected through rural development

Nanoporous networks as effective stabilisation matrices for nanoscale zero-valent iron and groundwater pollutant removal

Nanoporous networks exhibit effective stabilisation properties for nanoscale zero-valent iron (nZVI) and nZVI, with its reductive potentials and wide availability, offers degradative remediation of environmental contaminants.</p

A unified model for holistic power usage in cloud datacenter servers

Cloud datacenters are compute facilities formed by hundreds and thousands of heterogeneous servers requiring significant power requirements to operate effectively. Servers are composed by multiple interacting sub-systems including applications, microelectronic processors, and cooling which reflect their respective power profiles via different parameters. What is presently unknown is how to accurately model the holistic power usage of the entire server when including all these sub-systems together. This becomes increasingly challenging when considering diverse utilization patterns, server hardware characteristics, air and liquid cooling techniques, and importantly quantifying the non-electrical energy cost imposed by cooling operation. Such a challenge arises due to the need for multi-disciplinary expertise required to study server operation holistically. This work provides a unified model for capturing holistic power usage within Cloud datacenter servers. Constructed through controlled laboratory experiments, the model captures the relationship of server power usage between software, hardware, and cooling agnostic of architecture and cooling type (air and liquid). An exciting prospect is the ability to quantify the amount of non-electrical power consumed through cooling, allowing for more realistic and accurate server power profiles. This work represents the first empirically supported analysis and modeling of holistic power usage for Cloud datacenter servers, and bridges a significant gap between computer science and mechanical engineering research. Model validation through experiments demonstrates an average standard error of 3% for server power usage within both air and liquid cooled environments

MPGDs in Compton imaging with liquid-xenon

The interaction of radiation with liquid xenon, inducing both scintillation and ionization signals, is of particular interest for Compton-sequences reconstruction. We report on the development and recent results of a liquid-xenon time-projection chamber, dedicated to a novel nuclear imaging technique named "3 gamma imaging". In a first prototype, the scintillation is detected by a vacuum photomultiplier tube and the charges are collected with a MICROMEGAS structure; both are fully immersed in liquid xenon. In view of the final large-area detector, and with the aim of minimizing dead-zones, we are investigating a gaseous photomultiplier for recording the UV scintillation photons. The prototype concept is presented as well as preliminary results in liquid xenon. We also present soft x-rays test results of a gaseous photomultiplier prototype made of a double Thick Gaseous Electron Multiplier (THGEM) at normal temperature and pressure conditions.Comment: presented at MPGD09, CRETE, June 2009; to be published in JINST Proceedings, PDF, 10 pages, 11 figure

Instability and Spatiotemporal Dynamics of Alternans in Paced Cardiac Tissue

We derive an equation that governs the spatiotemporal dynamics of small amplitude alternans in paced cardiac tissue. We show that a pattern-forming linear instability leads to the spontaneous formation of stationary or traveling waves whose nodes divide the tissue into regions with opposite phase of oscillation of action potential duration. This instability is important because it creates dynamically an heterogeneous electrical substrate for inducing fibrillation if the tissue size exceeds a fraction of the pattern wavelength. We compute this wavelength analytically as a function of three basic length scales characterizing dispersion and inter-cellular electrical coupling.Comment: 4 pages, 3 figures, submitted to PR

Reintegration of Foreign Terrorist Fighter Families: A Framework of Best Practices for the U.S.

This report outlines a comprehensive framework of best practices in the reintegration of foreign terrorist fighter spouses and children (i.e., “the FTF family”). It collates and synthesizes a suite of interlocking principles to guide reintegration policy and implementation, covering practical challenges and programmatic objectives, the organizational structure and process of reintegration management in the U.S. context, the role of strategic communications and trauma-informed care, and the use of specialized risk assessment tools. Drawing on original work conducted in previous investigative streams, this report combines scholarly analyses from both theory and practice, interviews with practitioners and stakeholders, case study investigations, and the authors’ collective experiences in the field. Four key findings are central to this report. First, overarching policy and programmatic planning must take into account a suite of core objectives that are central to the reintegration of FTF families. Four main categories of objectives emerge within which are a range of policy and programmatic goals: align domestic policy and programmatic responses with the scope and nature of the returnee problem, develop a strategically guided approach to reintegration, integrate existing legal bases and systems of reintegration, and consider how FTF management may be instrumentalized towards broader policy objectives. These core objectives provide a compass for guiding how policymakers and practitioners navigate through the complex and interrelated challenges associated with reintegration work. Moreover, in order to achieve the goals and objectives outlined above, this report has identified a set of best practices relating to the formal structures and roles and responsibilities assigned to the reintegration mission community in the U.S. Second, we argue that the coordination and efficacy of reintegration activities can be improved with a greater focus on the role of strategic communications at the overarching planning and management level. It is broadly recognized that reintegration efforts should not be stovepiped. Less acknowledged is the role that a robust and integrated approach to strategic communications can play in helping to improve the sequencing and synchronicity of standard programming activities. This coordination issue also extends to how the age, gender and psychosocial needs of FTF returnees and their families are addressed. Third, we highlight the need for better incorporation of gender, age, and trauma-informed considerations at the program and case levels. The synthesis of trauma-informed approaches during the repatriation and reintegration process is vital and case managers must be appropriately equipped to develop tailored plans that harness gender, age, and familial factors too. Together, the coherent integration of compatible reintegration efforts and supporting activities will enable a more strategically focused approach. Finally, this report presents the broad parameters of a risk assessment tool for assessing FTF returnees and their families based on the project’s multidisciplinary and multisectoral findings. The framework is underpinned by a rigorous methodology and an evidence-based theory of change. However, it also seeks to be accessible and adaptable to ensure usability. The development and further refinement of this risk assessment instrument presents a promising avenue for future applied research

Rubber Impact on 3D Textile Composites

A low velocity impact study of aircraft tire rubber on 3D textile-reinforced composite plates was performed experimentally and numerically. In contrast to regular unidirectional composite laminates, no delaminations occur in such a 3D textile composite. Yarn decohesions, matrix cracks and yarn ruptures have been identified as the major damage mechanisms under impact load. An increase in the number of 3D warp yarns is proposed to improve the impact damage resistance. The characteristic of a rubber impact is the high amount of elastic energy stored in the impactor during impact, which was more than 90% of the initial kinetic energy. This large geometrical deformation of the rubber during impact leads to a less localised loading of the target structure and poses great challenges for the numerical modelling. A hyperelastic Mooney-Rivlin constitutive law was used in Abaqus/Explicit based on a step-by-step validation with static rubber compression tests and low velocity impact tests on aluminium plates. Simulation models of the textile weave were developed on the meso- and macro-scale. The final correlation between impact simulation results on 3D textile-reinforced composite plates and impact test data was promising, highlighting the potential of such numerical simulation tools