Experimental Study of Deformation and of Effective Width in Axially Loaded Sheet-stringer Panels

The deformation of two sheet-stringer panels subjected to end compression under carefully controlled end conditions was measured at a number of points and at a number of loads, most of which were above the load at which the sheet had begun to buckle. The two panels were identical except for the sheet, which was 0.70-inch 24st alclad for specimen 1 and 0.025-inch 24st aluminum alloy for specimen 6. A technique was developed for attaching Tuckerman optical strain gauges to the sheet without disturbing the strain distribution in the sheet by the method of attachment. This technique was used to explore the strain distribution in the sheet at various loads. The twisting and the bending of the stringers was measured by means of pointers attached to the stringers. The shape of the buckles in the sheet of specimen 6 was recorded at two loads by means of plaster casts. The sheet and the stringer loads at failure are compared with the corresponding loads for five similar panels tested at the Navy Model Basin. A detailed comparison is made between the measured deformation of the buckled sheet and the deformation calculated from approximate theories for the deformation in a rectangular sheet with freely supported edges buckling under end compression advanced by Timoshenko, Frankland, and Marguerre. The measured effective width for the specimens is compared with the effective width given by nine different relations for effective width as a function of the edge stress divided by the buckling stress of the sheet. The analysis of the measured stringer deformation is confined to an application of Southwell's method of plotting deformation against deformation over load. It was concluded that the stringer failure in both specimens were due to an instability in which the stringer was simultaneously twisted and bent as a column

Estimation of gross land-use change and its uncertainty using a Bayesian data assimilation approach

We present a method for estimating land-use change using a Bayesian data assimilation approach. The approach provides a general framework for combining multiple disparate data sources with a simple model. This allows us to constrain estimates of gross land-use change with reliable national-scale census data, whilst retaining the detailed information available from several other sources. Eight different data sources, with three different data structures, were combined in our posterior estimate of land use and land-use change, and other data sources could easily be added in future. The tendency for observations to underestimate gross land-use change is accounted for by allowing for a skewed distribution in the likelihood function. The data structure produced has high temporal and spatial resolution, and is appropriate for dynamic process-based modelling. Uncertainty is propagated appropriately into the output, so we have a full posterior distribution of output and parameters. The data are available in the widely used netCDF file format from http://eidc.ceh.ac.uk/

Compressive Tests of a Monocoque Box

A monocoque box specimen of aluminum alloy was subjected to end compression and the strains in the stringers were measured up to loads at which permanent set became noticeable. The stringer strains at low loads agreed closely with those computed from the assumption of uniform stress distribution. Buckling of the 0.026-inch sheet between stringers and of the 0.075-inch shear web took place at stresses in accord with theoretical values. Permanent set became noticeable at a load of 115,200 pounds, corresponding to an average stringer stress of about 16,000 pounds per square inch. The measured average strain above the first buckling load was within 2 percent of the theoretical strain as calculated from the dimensions of the box and effective width formulas due to Marguerre and to Cox

Analyzing the Financial Relationship between Railway Industry Players in Shared Railway Systems: The Train Operator’s Perspective

Capacity pricing and allocation play an important role in efficient management of railway corridors, especially shared ones. This paper analyzes how Train Operators (TOs) would respond to different track-access charges, as a first step to understand the relationship between Train Operators and Infrastructure Manger (IM) in railway systems with some level of vertical separation. By modeling a corridor whose users are long-distance high-speed trains and freight trains along the entire corridor, and commuter trains offering services around large urban areas in the corridor, this paper narrows down the focus on each individual operator, looking at the factors that drive each operator's ultimate service levels. Assuming an environment where the TOs are competing for capacity, financial goals and boundary conditions of each TO are derived, and a number of sensitivity analyses for various typical and extreme conditions are performed. This model allows to anticipate how TOs would respond to track-access charges, and can thus help the government, the regulators, and the IMs in the design of appropriate capacity pricing and allocation schemes

Learning from Learning Disruption: A Resource for Schools

When the COVID-19 pandemic started in March 2020 schools across the globe were forced to close. Since then, on a stop-start basis, schools have reopened. Many schools, however, are still experiencing the ongoing effects of COVID-19 on pupil and teacher absence as well as the social, emotional, physical and academic impact on the entire school community. While the world has experienced global pandemics like Spanish flu before, the COVID-19 pandemic has been unprecedented. In May 2020 United Kingdom Research Innovation(UKRI) and the Economic and Social Research Council (ESRC) awarded a team of researchers at IOE, UCL’s Faculty of Education and Society with funding to explore the challenges the COVID-19 crisis set primary school teachers. One part of this research was to conduct a review of research on previous learning disruptions to see if we could learn anything from these events that might match with the COVID-19 pandemic. This booklet summarises: What we did and why we did it What we found and educators’ reflections on how it aligned with the COVID-19 learning disruption What we recommended based on our findings and educators’ recommendations for schools and policy makers We have shared these findings with educators to combine their reflections on our findings with their experiences

Barriers to infection of human cells by feline leukemia virus: insights into resistance to zoonosis

The human genome displays a rich fossil record of past gamma-retrovirus infections, yet no current epidemic is evident, despite environmental exposure to viruses that infect human cells in vitro. Feline leukemia viruses (FeLVs) rank high on this list, but domestic or workplace exposure has not been associated with detectable serological responses. Non-specific inactivation of gamma-retroviruses by serum factors appears insufficient to explain these observations. To investigate further we explored the susceptibility of primary and established human cell lines to FeLV-B, the most likely zoonotic variant. Fully permissive infection was common in cancer-derived cell lines, but was also a feature of non-transformed keratinocytes and lung fibroblasts. Cells of haematopoietic origin were less generally permissive and formed discrete groups on the basis of high or low intracellular protein expression and virion release. Potent repression was observed in primary human blood mononuclear cells and a subset of leukemia cell lines. However, the early steps of reverse transcription and integration appear to be unimpaired in non-permissive cells. FeLV-B was subject to G->A hypermutation with a predominant APOBEC3G signature in partially permissive cells but was not mutated in permissive cells or in non-permissive cells that block secondary viral spread. Distinct cellular barriers that protect primary human blood cells are likely to be important in protection against zoonotic infection with FeLV

Research evidence to support primary school inspection post-COVID

This policy briefing is intended to inform discussion on how Ofsted inspections might best resume at an appropriate time, given the extensive disruption COVID has brought and continues to bring to English primary schools. The briefing draws on findings from a series of research projects based at the IOE, UCL’s Faculty of Education and Society and conducted between May 2020 and September 2021, using surveys, systematic literature reviews and case study methods. The research projects have highlighted just how much schools’ experiences have varied. They also show just how resourceful and resilient schools and their communities have been in navigating a way through the many difficult dilemmas the pandemic has raised, even when there have been no obvious roadmaps to follow. The research evidence we present and the recommendations that follow are intended to inform conversations in the field about the best ways forward in education. They build on the knowledge and experience that primary schools have acquired from dealing with the pandemic first hand

Political Settlements and Development

Few concepts have captured the imagination of the conflict and development communities in recent years as powerfully as the idea of a ‘political settlement’. At its most ambitious, ‘political settlements analysis’ (PSA) promises to explain why conflicts occur and states collapse, the conditions for their successful rehabilitation, different developmental pathways from peace, and how to better fit development policy to country context. Yet despite the meteoric rise of the term and its tremendous promise, not all is well in the world of PSA. Rival definitions of the concept abound; there are disagreements about its scope and the way it should be used; a growing schism between conflict specialists and economists; basic concepts are ambiguous; and little progress has been made on measurement. This book consequently has three main aims. The first is to argue for a revised definition of a political settlement, capable of unifying its diverse strands. The second is to put the concept on a more solid theoretical and scientific footing, providing a method for measuring and categorizing political settlements, using both qualitative case studies and a large-n statistical analysis to illustrate its potential. And the third is to examine the implications of the findings for mainstream social science analysis and for policymakers

Public Health Implications of Evictions: Modeling the Costs for Landlords, Tenants, and Society

In the United States, more than 13% of renters experience a formal or informal eviction in their lifetime. Forced moves contribute to a decline in job status, mental and physical health, material possessions, safety, social networks, housing aid, and neighborhood stability. Previous research has explored the risk factors, causes, and costs to those burdened by evictions. However, the costs of evictions incurred by all stakeholders involved in the process of evictions and homelessness remain largely unexplored. The homeownership rate in New Haven is less than 30%, and more than 52% of households are ‘cost-burdened,’ meaning more than 30% of income “is spent on housing costs associated with owning or renting a home.” Thus, this project set out to analyze the contributing burdens of costs within New Haven, Connecticut.https://elischolar.library.yale.edu/ysph_pbchrr/1016/thumbnail.jp