Numerical analysis of hot deep drawing of din 27MNCRB5 steel sheets under controlled stretching

Hot stamping has been widely studied and increasingly applied in the automotive industry. This process is characterized by its ability to stamp high strength steels, yielding products with high mechanical strength, thus reducing the weight of stamped components and therefore the vehicles weight. It also demands less energy because steel sheets are heated by induction, more efficient than electric furnaces. With controlled stretching it is possible to manufacture thinner stamped parts with high mechanical strength, therefore it is necessary to know the formability limits to prevent failure and achieve the largest possible thickness reduction. In this work the hot formability of DIN 27MnCrB5 steel sheets under stretching conditions was evaluated by numerical simulation with the finite element software Forge2008. The numerical results were compared to experimental results. Initially hot tensile tests were simulated to define the strain rate in different regions of the sample and to evaluate the deformation at fracture. For tests at 700, 800 and 900ºC it was found that the strain rates vary from 0.01 to 0.5 s-1. Experimental tensile tests were also carried out with the same conditions as simulated. Both simulation and experiments presented very similar results for the ultimate tensile strength, and therefore it was possible to assume the experimental fracture strain as a consistent input for the numerical models. With the results of the tensile tests, hot Nakazima tests were simulated to evaluate the highest dome which could be formed without failure risks caused by sheet thickness thinning. The simulation results were validated by experimental tests, and as a result, a new numerical strategy was elaborated to define the hot formability based on the plastic instability and necking localization as a function of the stamping temperature and blank dimensions

Development of a second generation prototype reflectometer for reflectance measurement in space Final technical report

Prototype reflectometer development for reflection measurements in spac

On the poverty of a priorism: technology, surveillance in the workplace and employee responses

Many debates about surveillance at work are framed by a set of a priori assumptions about the nature of the employment relationship that inhibits efforts to understand the complexity of employee responses to the spread of new technology at work. In particular, the debate about the prevalence of resistance is hamstrung from the outset by the assumption that all apparently non-compliant acts, whether intentional or not, are to be counted as acts of resistance. Against this background this paper seeks to redress the balance by reviewing results from an ethnographic study of surveillance-capable technologies in a number of British workplaces. It argues for greater attention to be paid to the empirical character of the social relations at work in and through which technologies are deployed and in the context of which employee responses are played out

A simple proof of the Markoff conjecture for prime powers

We give a simple and independent proof of the result of Jack Button and Paul Schmutz that the Markoff conjecture on the uniqueness of the Markoff triples (a,b,c), where a, b, and c are in increasing order, holds whenever $c$ is a prime power.Comment: 5 pages, no figure

Nanotechnology in multimodal theranostic capsule endoscopy

Video capsule endoscopy (VCE) has become a clinically accepted diagnostic modality in the last 20 years and has established a technological roadmap for other capsule endoscopy (CE) devices, incorporating microscale technology, a local power supply and wireless communication. However, VCE does not provide a therapeutic function and research in therapeutic capsule endoscopy (TCE) has been limited. This paper proposes a new route towards viable TCE based on multiple CE devices including essential nanoscale components. A first device is used for multimodal diagnosis, with quantitative microultrasound as a complement to video imaging. Ultrasound-enhanced fluorescent marking of sites of pathology allows follow-up with a second device for therapy. This is based on fluorescence imaging and ultrasound-mediated targeted drug delivery. Subsequent treatment verification and monitoring with a third device exploits the minimally invasive nature of CE. Clinical implementation of a complete patient pathway remains the subject of research but several key components have been prepared in early prototype form. These are described, along with gaps that remain to be filled

Models and metaphors: complexity theory and through-life management in the built environment

Complexity thinking may have both modelling and metaphorical applications in the through-life management of the built environment. These two distinct approaches are examined and compared. In the first instance, some of the sources of complexity in the design, construction and maintenance of the built environment are identified. The metaphorical use of complexity in management thinking and its application in the built environment are briefly examined. This is followed by an exploration of modelling techniques relevant to built environment concerns. Non-linear and complex mathematical techniques such as fuzzy logic, cellular automata and attractors, may be applicable to their analysis. Existing software tools are identified and examples of successful built environment applications of complexity modelling are given. Some issues that arise include the definition of phenomena in a mathematically usable way, the functionality of available software and the possibility of going beyond representational modelling. Further questions arising from the application of complexity thinking are discussed, including the possibilities for confusion that arise from the use of metaphor. The metaphor of a 'commentary machine' is suggested as a possible way forward and it is suggested that an appropriate linguistic analysis can in certain situations reduce perceived complexity

Evaluation of expressive writing for postpartum health: A randomized controlled trial

Pregnancy, birth and adjusting to a new baby is a potentially stressful time that can negatively affect the health of women. There is some evidence that expressive writing can have positive effects on psychological and physical health, particularly during stressful periods. The current study aimed to evaluate whether expressive writing would improve women’s postpartum health. A randomized controlled trial was conducted with three conditions: expressive writing (n=188), a control writing task (n=213), or normal care (n=163). Measures of psychological health, physical health and quality of life were measured at baseline (6-12 weeks postpartum), 1 month and 6 months later. Ratings of stress were taken before and after the expressive writing task. Intent-to-treat analyses showed no significant differences between women in the expressive writing, control writing and normal care groups on measures of physical health, anxiety, depression, mood or quality of life at 1 and 6 months. Uptake and adherence to the writing tasks was low. However, women in the expressive writing group rated their stress as significantly reduced after completing the task. Cost analysis suggest women who did expressive writing had the lowest costs in terms of healthcare service use and lowest cost per unit of improvement in quality of life. Results suggest expressive writing is not effective as a universal intervention for all women 6-12 weeks postpartum. Future research should examine expressive writing as a targeted intervention for women in high-risk groups, such as those with mild or moderate depression, and further examine cost-effectiveness

Using Variable-Rate Alerting to Counter Boredom in Human Supervisory Control

A low task load, long duration experiment was conducted to evaluate the impact of cyclical attention switching strategies on operator performance in supervisory domains. The impetus for such a study stems from the lack of prior work to improve human-system performance in low task load supervisory domains through the use of design interventions. In this study, a design intervention in the form of auditory alerts is introduced and the effects of the alerts are examined. The test bed consists of a video game-like simulation environment, which allows a single operator the ability to supervise multiple unmanned vehicles. Each participant in the study completed two different four hour sessions, with and without the alerts. The results suggest that the alerts can be useful for operators who are distracted for a considerable amount of time, but that the alerts may not be appropriate for operators who are able to sustain directed attention for prolonged periods.United States. Office of Naval Researc

Tidal flat deposits of the Lower Proterozoic Campbell Group along the southwestern margin of the Kaapvaal Craton, Northern Cape Province, South Africa

Lower Proterozoic stromatolites and associated clastic carbonate deposits of the Campbell Group, from the southern margin (Prieska area) of the Kaapvaal Craton, northern Cape Province, are described. Contrary to previous interpretations (Beukes, 1978; 1980a) shallow subtidal to supratidal facies are recognised and discussed in regional context. An alternative model for the facies development of the Campbell Group is proposed

Ontology of core data mining entities

In this article, we present OntoDM-core, an ontology of core data mining entities. OntoDM-core defines themost essential datamining entities in a three-layered ontological structure comprising of a specification, an implementation and an application layer. It provides a representational framework for the description of mining structured data, and in addition provides taxonomies of datasets, data mining tasks, generalizations, data mining algorithms and constraints, based on the type of data. OntoDM-core is designed to support a wide range of applications/use cases, such as semantic annotation of data mining algorithms, datasets and results; annotation of QSAR studies in the context of drug discovery investigations; and disambiguation of terms in text mining. The ontology has been thoroughly assessed following the practices in ontology engineering, is fully interoperable with many domain resources and is easy to extend