Pressure Reduction on Wide Culverts with EPS Geofoam Backfill

Buried structures may be subjected to excessive stresses that are detrimental to their expected service life. A review of previous design methods shows that there are effective methods to reduce loadings on narrow culverts. The Induced Trench Method introduces compressible fill over a buried structure to mobilize positive arching, and transfer stresses to the side fills. However, this method has not been studied with Bridge Culverts (large spanning culverts). This study evaluates the use of EPS (Expanded Polystyrene, Geofoam) as a compressible/lightweight fill material. The displacements and stresses of the classic narrow trench are examined in detail using the finite difference computer modeling program, FLAC (Fast Lagrangian Analysis of Continua). The narrow trench is then altered to study the overall effect of thickness and width of the compressible zone upon the stresses acting on the buried structure. To extend the service life of the culvert, recommendations are given on how to design with nearly equivalent horizontal and vertical stresses within an Induced Trench. In deeply buried structures, great consideration must also be given to the stresses applied on the geofoam. When geofoam is subjected to large confining axial and confining pressures, it exhibits modulus degradation and can lead to large deformations. This is observed in detail with the case study of the failure of the geofoam within a Bridge Culvert located in Carrs Creek, NY. Proper design methods with geofoam on large spanning, deeply buried culverts are evaluated and outlined. The effects of continuous joints, mixed densities, hydrostatic pressures, overloading, confining stresses, and creep on EPS geofoam are considered. An exponential model that captures the effect of confinement on modulus degradation has been programmed using FISH (FLAC internal coding) and verified with complimentary laboratory testing. A properly designed culvert section is shown, in which all the design flaws of the culvert at Carrs Creek have been addressed. The stresses in the geofoam and underlying culvert are reduced to tolerable stress levels, while deformations have been greatly reduced. The results of this computer analysis have been presented in such a way that they can be used to aid in proper design of buried structures, using geofoam to reduce stresses and surficial displacements

A hybrid multilevel converter for medium and high voltage applications

This paper investigates the suitability of the hybrid multilevel converter for medium and high voltage application. The converter operation, modulation, and capacitor voltage balancing method are described in detail. The ability of the hybrid multilevel converter to operate with different modulation indices and load power factors is investigated. It has been established that the hybrid multilevel converter is capable of operating independent of load power factor. Operation with variable modulation index increases voltage stresses on the converter switches and does not alter the fundamental voltage magnitude as in all known voltage source converter topologies. The viability of the hybrid multilevel converter for medium and high voltage applications is confirmed by simulations

Is cultural sensitivity always a good thing? Arguments for a universalist social work

The requirement for social workers to be sensitive to cultural difference has now become accepted as an essential component of best practice – indeed, social workers failing to display sensitivity to cultural differences would most likely be seen to be in contravention of most professional ethics frameworks. However, closer scrutiny as to exactly how and to what degree one should display cultural sensitivity in practice reveals a complex set of ethical and philosophical dilemmas for social workers. This chapter is concerned with a discussion of these. The chapter concludes with a call for the reconstruction of a universalist ethics in social work, and offers Nussbaum and Sen’s ‘Capability Framework’ as offering a way in which this could be done in Social Work practice

The intensification of neoliberalism and the commodification of human need – a social work perspective

The drive toward the commodification of human society was first explained by Marx and Engels in the Communist Manifesto as a manifestation of the territorial expansion of capitalist relations across the globe. While this dimension of capitalist expansion continues apace, this paper discuses the further dimension of the way capitalist social relations are intensified in the contemporary period of neoliberal capitalism. This involves reconstruction of subjectivity in the context of the rolling back of the gains from the post-war Keynesian period. We take a critical look at the deployment of terms such as 'empowerment' and 'resilience' in policy discourses and the way these are being used to reconstruct the relationship between the state and citizenry in this period, and the impact this is having on UK Social Work

Stochastic Randomized Response Model for a Quantitative Sensitive Random Variable

A new stochastic randomized response model is introduced that is useful for estimating the population mean of a sensitive quantitative variable. The proposed stochastic randomized response model is an extension of the stochastic randomized response model from a qualitative sensitive variable to a quantitative variable found in Singh (2002). The stochastic nature of a randomized response device helps increase a respondent’s cooperation while collecting information on sensitive variables in a society. The Bar-Lev, Bobovitch, and Boukai (2004) model is shown to be a special case of the proposed model

Incremental placement for layout driven optimizations on FPGAs

This paper presents an algorithm to update the placement of logic elements when given an incremental netlist change. Specifically, these algorithms are targeted to incrementally place logic elements created by layout-driven circuit restruc-turing techniques. The incremental placement engine as-sumes that the restructuring algorithms provide a list of new logic elements along with preferred locations for each of these new elements. It then tries to shift non-critical logic elements in the original placement out of the way to satisfy the preferred location requests. Our algorithm considers modern FPGA architectures with clustered logic blocks that have numerous architectural constraints. Experiments indi-cate that our technique produces results of extremely high quality. 1

An Adaptive Flow Solver for Air-Borne Vehicles Undergoing Time-Dependent Motions/Deformations

This report describes a concurrent Euler flow solver for flows around complex 3-D bodies. The solver is based on a cell-centered finite volume methodology on 3-D unstructured tetrahedral grids. In this algorithm, spatial discretization for the inviscid convective term is accomplished using an upwind scheme. A localized reconstruction is done for flow variables which is second order accurate. Evolution in time is accomplished using an explicit three-stage Runge-Kutta method which has second order temporal accuracy. This is adapted for concurrent execution using another proven methodology based on concurrent graph abstraction. This solver operates on heterogeneous network architectures. These architectures may include a broad variety of UNIX workstations and PCs running Windows NT, symmetric multiprocessors and distributed-memory multi-computers. The unstructured grid is generated using commercial grid generation tools. The grid is automatically partitioned using a concurrent algorithm based on heat diffusion. This results in memory requirements that are inversely proportional to the number of processors. The solver uses automatic granularity control and resource management techniques both to balance load and communication requirements, and deal with differing memory constraints. These ideas are again based on heat diffusion. Results are subsequently combined for visualization and analysis using commercial CFD tools. Flow simulation results are demonstrated for a constant section wing at subsonic, transonic, and a supersonic case. These results are compared with experimental data and numerical results of other researchers. Performance results are under way for a variety of network topologies

Implications of the Articulation Gap between Geography Learners in Secondary Schools and University

There is a concern in South Africa that most learners arrive at university underprepared. This is also a major concern for students who enroll for the BEd programme specialising in geography education. Due to the learners’ articulation gap, they are unable to cope with the standard that is expected of them. Hence this study investigated the level of geography learners’ prepared-ness when they arrive at university. The aim of the study was to investigate the challenges experienced by geography students in their first-year of study. The researchers used a qualitative approach grounded in phenomenology as the research design. Purposive sampling was used to select students who failed geography education in both semesters in their first-year of study, the academic year 2016. Two lecturers who teach geography in the first-year were sampled. The geography curriculum used in the secondary schools and university were also reviewed to determine the extent of alignment between the two. A the-matic approach was used to analyse the data. The results of the study revealed that geography students enter university without proper preparation, and are therefore unable to cope with their first-year of study. The study further revealed that teachers who teach geography in secondary school are not sufficiently trained to teach geography, which results in their engaging in surface learning as opposed to deep learning. The study recommends that there be collaboration between secondary schools and universities to discuss the university’s expectations with regard to learner preparedness. Moreover, geography teachers should be trained on an on-going basis in order for them to keep up with current trends in the area of geography education

Models and Materials for Generalized Kitaev Magnetism

The exactly solvable Kitaev model on the honeycomb lattice has recently received enormous attention linked to the hope of achieving novel spin-liquid states with fractionalized Majorana-like excitations. In this review, we analyze the mechanism proposed by G. Jackeli and G. Khaliullin to identify Kitaev materials based on spin-orbital dependent bond interactions and provide a comprehensive overview of its implications in real materials. We set the focus on experimental results and current theoretical understanding of planar honeycomb systems (Na$_2$IrO$_3$, $\alpha$-Li$_2$IrO$_3$, and $\alpha$-RuCl$_3$), three-dimensional Kitaev materials ($\beta$- and $\gamma$-Li$_2$IrO$_3$), and other potential candidates, completing the review with the list of open questions awaiting new insights.Comment: updated references, published versio