2D linear friction weld modelling of a Ti-6Al-4V T-joint

Most examples of linear friction weld process models have focused on joining two identically shaped workpieces. This article reports on the development of a 2D model, using the DEFORM finite element package, to investigate the joining of a rectangular Ti-6Al-4V workpiece to a plate of the same material. The work focuses on how this geometry affects the material flow, thermal fields and interface contaminant removal. The results showed that the material flow and thermal fields were not even across the two workpieces. This resulted in more material expulsion being required to remove the interface contaminants from the weld line when compared to joining two identically shaped workpieces. The model also showed that the flash curves away from the weld due to the rectangular upstand "burrowing" into the base plate.Understanding these critical relationships between the geometry and process outputs is crucial for further industrial implementation of the LFW process.EPSRC, The Welding Institut

Handelsstruktur und nationale Interessen konterkarieren GUS-Integration

Die vielfachen Integrationsbemühungen der GUS-Staaten in den letzten Jahren waren nicht in der Lage, den bemerkenswerten Rückgang des Intra-GUS-Handels zu Gunsten einer zunehmenden Handelsverflechtung der GUS-Staaten mit Drittländern, insbesondere der EU, zu stoppen. Trotz dieser kontinuierlichen Ausweitung der Handelsaktivitäten zwischen der EU und den GUS-Staaten bewegen sich die Handelsbeziehungen zwischen diesen Regionen jedoch nach wie vor auf einem niedrigen Niveau. Sie sind weitaus weniger entwickelt als diejenigen zwischen der EU und den ostmitteleuropäischen Staaten. Wichtige Impulse für eine verbesserte Exportstruktur und höhere Exportdynamik der GUS-Staaten wären vom Zufluss ausländischen Kapitals zu erwarten. Erst mit einer nachhaltigen Verbesserung der wirtschaftlichen Rahmenbedingungen in den GUS-Ländern wird sich allerdings der bisher geringe Zustrom von Auslandskapital verstärken. Diesen Fragen geht eine ausführliche Analyse der Handelsbeziehungen und der handelspolitischen Rahmenbedingungen innerhalb der GUS-Staaten sowie der Entwicklung des Außenhandels der GUSStaaten im Rahmen ihrer Annäherung an die EU und ihrer Integration in den Welthandel nach, die soeben in der Reihe der Arbeiten aus dem Osteuropa-Institut München (Working Papers) erschienen ist.

Cognitive consequences of sleep deprivation, shift work, and heat exposure for underground miner

The extent to which an underground miner’s alertness is influenced by sleep deprivation, shift work, and working in elevated temperatures is currently unknown. Actigraphy and psychomotor vigilance data were collected from nineteen underground miners over 28 consecutive days. Core body temperature data was also gathered during four scheduled work shifts. Participants experienced shortened sleep durations and poor sleep efficiency throughout the study. Significant increases in reaction time occurred over the course of night shifts, a decline that was not observed during day shifts. A strong, negative correlation between core body temperature and reaction time was present throughout day shifts but did not appear during night shifts. Poor sleep and altered circadian rhythms appear to negatively affect the alertness of participants during work times. An inadequate adaptation to night work schedules may be indicated by the poor alertness and absent relationship between core body temperature and performance observed during night shifts.Master's These

A behavioral study of Roth versus traditional retirement savings accounts

Motivated by a popular perception that Roth accounts are welfare-improving for most people, this paper compares the effects of mandated Traditional (tax-deferred) or Roth (taxprepaid) retirement policies in a controlled laboratory setting. Selection effects, which complicate analyses of observational data, are avoided by random assignment to policies. Subjects receive exogenous incomes during “working” periods, followed by no-income “retirement” periods. In each period, subjects decide how many lab dollars to convert into “takehome pay,” akin to consumption with diminishing returns. Subjects’ decisions determine retirement savings and tax payments. Flat income and tax-rate profiles facilitate the analysis of behavioral factors like present-period tax avoidance, while optimal consumption and after-tax savings are identical for both treatments. Our results show that observed savings are suboptimal in both treatments and are influenced by gender, patience, and risk aversion measures. In contrast to conventional wisdom, there are no significant differences between policies; if anything, the Traditional treatment leads to marginally higher post-retirement consumption

Costs Of Using “Tiny Targets” to Control Glossina fuscipes fuscipes, a Vector of Gambiense Sleeping Sickness in Arua District of Uganda

Introduction To evaluate the relative effectiveness of tsetse control methods, their costs need to be analysed alongside their impact on tsetse populations. Very little has been published on the costs of methods specifically targeting human African trypanosomiasis. Methodology/Principal Findings In northern Uganda, a 250 km2 field trial was undertaken using small (0.5 X 0.25 m) insecticide-treated targets (“tiny targets”). Detailed cost recording accompanied every phase of the work. Costs were calculated for this operation as if managed by the Ugandan vector control services: removing purely research components of the work and applying local salaries. This calculation assumed that all resources are fully used, with no spare capacity. The full cost of the operation was assessed at USD 85.4 per km2, of which USD 55.7 or 65.2% were field costs, made up of three component activities (target deployment: 34.5%, trap monitoring: 10.6% and target maintenance: 20.1%). The remaining USD 29.7 or 34.8% of the costs were for preliminary studies and administration (tsetse surveys: 6.0%, sensitisation of local populations: 18.6% and office support: 10.2%). Targets accounted for only 12.9% of the total cost, other important cost components were labour (24.1%) and transport (34.6%). Discussion Comparison with the updated cost of historical HAT vector control projects and recent estimates indicates that this work represents a major reduction in cost levels. This is attributed not just to the low unit cost of tiny targets but also to the organisation of delivery, using local labour with bicycles or motorcycles. Sensitivity analyses were undertaken, investigating key prices and assumptions. It is believed that these costs are generalizable to other HAT foci, although in more remote areas, with denser vegetation and fewer people, costs would increase, as would be the case for other tsetse control techniques

Disentangling and modeling interactions in fish with burst-and-coast swimming reveal distinct alignment and attraction behaviors

We combine extensive data analyses with a modeling approach to measure, disentangle, and reconstruct the actual functional form of interactions involved in the coordination of swimming in Rummy-nose tetra (Hemigrammus rhodostomus). This species of fish performs burst-and-coast swimming behavior that consists of sudden heading changes combined with brief accelerations followed by quasi-passive, straight decelerations. We quantify the spontaneous stochastic behavior of a fish and the interactions that govern wall avoidance and the attraction and alignment to a neighboring fish, the latter by exploiting general symmetry constraints for the interactions. In contrast with previous experimental works, we find that both attraction and alignment behaviors control the reaction of fish to a neighbor. We then exploit these results to build a model of spontaneous burst-and-coast swimming and interactions of fish, with all parameters being estimated or directly measured from experiments. This model quantitatively reproduces the key features of the motion and spatial distributions observed in experiments with a single fish and with two fish. This demonstrates the power of our method that exploits large amounts of data for disentangling and fully characterizing the interactions that govern collective behaviors in animals groups. Moreover, we introduce the notions of "dumb" and "intelligent" active matter and emphasize and clarify the strong differences between them.Comment: Supplementary Information (PDF text + 5 videos) can be downloaded at http://www.lpt.ups-tlse.fr/spip.php?action=acceder_document&arg=2240&cle=f7d43896e78b1b15dff009dc7769eac3c956c76a&file=zip%2FSI_Web.zi

Climate Action In Megacities 3.0

"Climate Action in Megacities 3.0" (CAM 3.0) presents major new insights into the current status, latest trends and future potential for climate action at the city level. Documenting the volume of action being taken by cities, CAM 3.0 marks a new chapter in the C40-Arup research partnership, supported by the City Leadership Initiative at University College London. It provides compelling evidence about cities' commitment to tackling climate change and their critical role in the fight to achieve global emissions reductions