Direct ink writing of custom UV curable rubbers with radiation absorbing particles and its challenges

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Conformal and custom radiation shielding composites for human extremity protection enabled by non-planar additive manufacturing

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IMECE2009-12660 MECHANICAL DESIGN AND VIBRO-ACOUSTIC TESTING OF ULTRATHIN CARBON FOILS FOR A SPACECRAFT INSTRUMENT

ABSTRACT IBEX-Hi is an electrostatic analyzer spacecraft instrument designed to measure the energy and flux distribution of energetic neutral atoms (ENAs) emanating from the interaction zone between the Earth's solar system and the Milky Way galaxy. A key element to this electro-optic instrument is an array of fourteen carbon foils that are used to ionize the ENAs. The foils are comprised of an ultrathin (50-100Å thick) layer of carbon suspended across the surface of an electroformed Nickel wire screen, which in turn is held taught by a metal frame holder. The electroformed orthogonal screen has square wire elements, 12.7 m thick, with a pitch of 131.1 wires/cm. Each foil holder has an open aperture approximately 5 cm by 2.5 cm. Designing and implementing foil holders with such a large surface area has not been attempted for spaceflight in the past and has proven to be extremely challenging. The delicate carbon foils are subject to fatigue failure from the large acoustic and vibration loads that they will be exposed to during launch of the spacecraft. This paper describes the evolution of the foil holder design from previous space instrument applications to a flight-like IBEX-Hi prototype. Vibro-acoustic qualification tests of the IBEX-Hi prototype instrument and the resulting failure of several foils are summarized. This is followed by a discussion of iterative foil holder design modifications and laser vibrometer modal testing to support future fatigue failure analyses. The results of these activities indicate that there is no strong dependency of the natural frequencies or transmissibilities of the foils on the different foil holder and screen configurations. However, for all foil holder designs, the natural frequencies of the foils were observed to decrease noticeably from exposure to acoustic testing. These test results, when combined with foil holder assembly considerations, suggest that the welded frame and integrated screen designs should be incorporated into the architecture of the IBEX-Hi flight instrument. INTRODUCTION The IBEX-Hi spacecraft instrument, shown in As discussed in [1] and [2], the mechanical design of the IBEX-Hi instrument proved to be quite challenging. Harsh environmental conditions imposed by the IBEX mission, combined with the need for delicate, high precision, and stable mechanical features, required that detailed structural and thermal analyses be combined with extensive environmental testing to qualify the mechanical design. In references [1] and [2], the mechanical design, thermal and structural analyses, an

The CLEAR 2007 Evaluation

Abstract. This paper is a summary of the 2007 CLEAR Evaluation on the Classification of Events, Activities, and Relationships which took place in early 2007 and culminated with a two-day workshop held in May 2007. CLEAR is an international effort to evaluate systems for the perception of people, their activities, and interactions. In its second year, CLEAR has developed a following from the computer vision and speech communities, spawning a more multimodal perspective of research eval-uation. This paper describes the evaluation tasks, including metrics and databases used, and discusses the results achieved. The CLEAR 2007 tasks comprise person, face, and vehicle tracking, head pose estimation, as well as acoustic scene analysis. These include subtasks performed in the visual, acoustic and audio-visual domains for meeting room and surveillance data.

Visual recognition of gestures in a meeting to detect when documents being talked about are missing

Meetings frequently involve discussion of documents and can be significantly affected if a document is absent. An agent system capable of spontaneously retrieving a document at the point it is needed would have to judge whether a meeting is talking about a particular document and whether that document is already present. We report the exploratory application of agent techniques for making these two judgements. To obtain examples from which an agent system can learn, we first conducted a study of participants making these judgements with video recordings of meetings. We then show that interactions between hands and paper documents in meetings can be used to recognise when a document being talked about is not to hand. The work demonstrates the potential for multimodal agent systems using these techniques to learn to perform specific, discourse-level tasks during meetings

Transient Stage Comparison of Couette Flow under Step Shear Stress and Step Velocity Boundary Conditions

Couette flow has been widely used in many industrial and research processes, such as viscosity measurement. For the study on thixotropic viscosity, step-loading, which includes (1) step shear stress and (2) step velocity conditions, is widely used. Transient stages of Couette flow under both step wall shear stress and step wall velocity conditions were investigated. The relative coefficient of viscosity was proposed to reflect the transient process. Relative coefficients of viscosity, dimensionless velocities and dimensionless development times were derived and calculated numerically. This article quantifies the relative coefficients of viscosity as functions of dimensionless time and step ratios when the boundary is subjected to step changes. As expected, in the absence of step changes, the expressions reduce to being functions of dimensionless time. When step wall shear stresses are imposed, the relative coefficients of viscosity changes from the values of the step ratios to their steady-state value of 1. but With step-increasing wall velocities, the relative coefficients of viscosity decrease from positive infinity to 1. The relative coefficients of viscosity increase from negative infinity to 1 under the step-decreasing wall velocity condition. During the very initial stage, the relative coefficients of viscosity under step wall velocity conditions is further from 1 than the one under step wall shear stress conditions but the former reaches 1 faster. Dimensionless development times grow with the step ratio under the step-rising conditions and approaches the constant value of 1.785 under the step wall shear stress condition, and 0.537 under the step wall velocity condition respectively. The development times under the imposed step wall shear stress conditions are always larger than the same under the imposed step wall velocity conditions

The Coevolution of Finance and Property Rights: Evidence from Transition Economies

The transition from communism to capitalism was necessarily accompanied by a sudden and abrupt increase in the financialization of society. This increase occurred in an environment that, even now, still has little experience with or expertise in financialization. Given that financialization occurred simultaneously with the growth and evolution of other political and economic institutions, the question arises: What was the effect on these other nascent institutions like property rights? This article empirically analyzes the relationship between financialization and property rights in transition countries. Using a unique monthly database of twenty transition countries over a period from 1989 to 2012, this article finds that the influence of financialization depends on which definition of “financialization” is used. In particular, increases in basic financial intermediation improved property rights. However, higher-order “financialization,” proxied here by the size of capital markets and the wages in the financial sector, appeared to have a negative impact on the development of broad-based property rights in transition

A Multi-Variant, Viral Dynamic Model of Genotype 1 HCV to Assess the in vivo Evolution of Protease-Inhibitor Resistant Variants

Variants resistant to compounds specifically targeting HCV are observed in clinical trials. A multi-variant viral dynamic model was developed to quantify the evolution and in vivo fitness of variants in subjects dosed with monotherapy of an HCV protease inhibitor, telaprevir. Variant fitness was estimated using a model in which variants were selected by competition for shared limited replication space. Fitness was represented in the absence of telaprevir by different variant production rate constants and in the presence of telaprevir by additional antiviral blockage by telaprevir. Model parameters, including rate constants for viral production, clearance, and effective telaprevir concentration, were estimated from 1) plasma HCV RNA levels of subjects before, during, and after dosing, 2) post-dosing prevalence of plasma variants from subjects, and 3) sensitivity of variants to telaprevir in the HCV replicon. The model provided a good fit to plasma HCV RNA levels observed both during and after telaprevir dosing, as well as to variant prevalence observed after telaprevir dosing. After an initial sharp decline in HCV RNA levels during dosing with telaprevir, HCV RNA levels increased in some subjects. The model predicted this increase to be caused by pre-existing variants with sufficient fitness to expand once available replication space increased due to rapid clearance of wild-type (WT) virus. The average replicative fitness estimates in the absence of telaprevir ranged from 1% to 68% of WT fitness. Compared to the relative fitness method, the in vivo estimates from the viral dynamic model corresponded more closely to in vitro replicon data, as well as to qualitative behaviors observed in both on-dosing and long-term post-dosing clinical data. The modeling fitness estimates were robust in sensitivity analyses in which the restoration dynamics of replication space and assumptions of HCV mutation rates were varied

The relationship between alcohol use and long-term cognitive decline in middle and late life: a longitudinal analysis using UK Biobank

Background Using UK Biobank data, this study sought to explain the causal relationship between alcohol intake and cognitive decline in middle and older aged populations. Methods Data from 13 342 men and women, aged between 40 and 73 years were used in regression analysis that tested the functional relationship and impact of alcohol on cognitive performance. Performance was measured using mean reaction time (RT) and intra-individual variation (IIV) in RT, collected in response to a perceptual matching task. Covariates included body mass index, physical activity, tobacco use, socioeconomic status, education and baseline cognitive function. Results A restricted cubic spline regression with three knots showed how the linear (β1 = −0.048, 95% CI: −0.105 to −0.030) and non-linear effects (β2 = 0.035, 95% CI: 0.007–0.059) of alcohol use on mean RT and IIV in RT (β1 = −0.055, 95% CI: −0.125 to −0.034; β2 = 0.034, 95% CI: 0.002–0.064) were significant adjusting for covariates. Cognitive function declined as alcohol use increased beyond 10 g/day. Decline was more apparent as age increased. Conclusions The relationship between alcohol use and cognitive function is non-linear. Consuming more than one UK standard unit of alcohol per day is detrimental to cognitive performance and is more pronounced in older populations