In Situ Thermal Inspection of Automated Fiber Placement Operations for Tow and Ply Defect Detection

The advent of Automated Fiber Placement (AFP) systems have aided the rapid manufacturing of composite aerospace structures. One of the challenges that AFP systems pose is the uniformity of the deposited prepreg tape layers, which complicates detection of laps, gaps, overlaps and twists. The current detection method used in industry involves halting fabrication and performing a time consuming, visual inspection of each tape layer. Typical AFP systems use a quartz lamp to heat the base layer to make the surface tacky as it deposits another tape layer. The innovation proposed in this paper is to use the preheated base layer as a through-transmission heat source for inspecting the newly added tape layer in situ using a thermographic camera mounted on to the AFP hardware. Such a system would not only increase manufacturing throughput by reducing inspection times, but it would also aid in process development for new structural designs or material systems by providing data on as-built parts. To this end, a small thermal camera was mounted onto an AFP robotic research platform at NASA, and thermal data was collected during typical and experimental layup operations. The data was post processed to reveal defects such as tow overlap/gap, wrinkling, and peel-up. Defects that would have been impossible to detect visually were also discovered in the data, such as poor/loss of adhesion between plies and the effects of vacuum debulking. This paper will cover the results of our experiments, and the plans for future versions of this inspection system

Early star formation traced by the highest redshift quasars

The iron abundance relative to alpha-elements in the circumnuclear region of quasars is regarded as a clock of the star formation history and, more specifically, of the enrichment by SNIa. We investigate the iron abundance in a sample of 22 quasars in the redshift range 3.0<z<6.4 by measuring their rest frame UV FeII bump, which is shifted into the near-IR, and by comparing it with the MgII 2798 flux. The observations were performed with a device that can obtain near-IR spectra in the range 0.8-2.4 um in one shot, thereby enabling an optimal removal of the continuum underlying the FeII bump. We detect iron in all quasars including the highest redshift (z=6.4) quasar currently known. The uniform observational technique and the wide redshift range allows a reliable study of the trend of the FeII/MgII ratio with redshift. We find the FeII/MgII ratio is nearly constant at all redshifts, although there is marginal evidence for a higher FeII/MgII ratio in the quasars at z~6. If the FeII/MgII ratio reflects the Fe/alpha abundance, this result suggests that the z~6 quasars have already undergone a major episode of iron enrichment. We discuss the possible implications of this finding for the star formation history at z>6. We also detect a population of weak iron emitters at z~4.5, which are possibly hosted in systems that evolved more slowly. Alternatively, the trend of the FeII/MgII ratio at high redshift may reflect significantly different physical conditions of the circumnuclear gas in such high redshift quasars.Comment: Replaced to match the accepted version (ApJL in press), 5 page

Atomistic origins of the phase transition mechanism in Ge2Sb2Te5

Combined static and molecular dynamics first-principles calculations are used to identify a direct structural link between the metastable crystalline and amorphous phases of Ge2Sb2Te5. We find that the phase transition is driven by the displacement of Ge atoms along the rocksalt [111] direction from the stable-octahedron to high-energy-unstable tetrahedron sites close to the intrinsic vacancy regions, which give rise to the formation of local 4-fold coordinated motifs. Our analyses suggest that the high figures of merit of Ge2Sb2Te5 are achieved from the optimal combination of intrinsic vacancies provided by Sb2Te3 and the instability of the tetrahedron sites provided by GeTe

Privacy Preserving Internet Browsers: Forensic Analysis of Browzar

With the advance of technology, Criminal Justice agencies are being confronted with an increased need to investigate crimes perpetuated partially or entirely over the Internet. These types of crime are known as cybercrimes. In order to conceal illegal online activity, criminals often use private browsing features or browsers designed to provide total browsing privacy. The use of private browsing is a common challenge faced in for example child exploitation investigations, which usually originate on the Internet. Although private browsing features are not designed specifically for criminal activity, they have become a valuable tool for criminals looking to conceal their online activity. As such, Technological Crime units often focus their forensic analysis on thoroughly examining the web history on a computer. Private browsing features and browsers often require a more in-depth, post mortem analysis. This often requires the use of multiple tools, as well as different forensic approaches to uncover incriminating evidence. This evidence may be required in a court of law, where analysts are often challenged both on their findings and on the tools and approaches used to recover evidence. However, there are very few research on evaluating of private browsing in terms of privacy preserving as well as forensic acquisition and analysis of privacy preserving internet browsers. Therefore in this chapter, we firstly review the private mode of popular internet browsers. Next, we describe the forensic acquisition and analysis of Browzar, a privacy preserving internet browser and compare it with other popular internet browser

Thermal degradation of formamidinium based lead halide perovskites into sym-triazine and hydrogen cyanide observed by coupled thermogravimetry-mass spectrometry analysis

The thermal stability and decomposition products of formamidinium, a widely used organic cation in perovskite solar cell formulation, were investigated. The thermal degradation experiments of formamidinium-based perovskites and their halide precursors were carried out under helium atmosphere and vacuum at a constant heating rate of 20 degrees C min(-1). In addition, pulsed heating steps were employed under illumination/dark conditions to simulate a more realistic working temperature condition for photovoltaic devices. The identification of gas decomposition products was based on the quadrupole mass spectrometry technique. The released amounts of sym-triazine, formamidine, and hydrogen cyanide (HCN) were observed to highly depend on the temperature. For the experimental conditions used in this study, sym-triazine was obtained as the thermal product of degradation at temperatures above 95 degrees C. Below this temperature, only formamidine and HCN generation routes were observed. The energy pathways of formamidinium thermal degradation under photovoltaic working temperature conditions were further assessed by density functional theory calculations. The results indicated that formamidinium was more resilient to thermal degradation and the release of irreversible decomposition products compared to methylammonium because of a larger enthalpy and activation energy obtained for the decomposition reactions. The HCN instantaneous concentration observed during the low temperature heating tests and the estimations of the maximum release of HCN achievable per meter-square of an FA based perovskite based solar cell were compared to acute exposure guideline levels of airborne HCN concentration

Hiring Individuals in Addiction Recovery: Characteristics, Levels of Concern and Willingness

Research suggests employment is a key factor in an individual’s recovery and employer’s views have historically limited opportunities for highly marginalized groups. Objectives: This study provides an analysis of views among employers regarding the hiring of individuals in addiction recovery. Methods: A convenience sample of 382 employers affiliated with the chambers of commerce was recruited to participate in this study. The authors used descriptive and inferential statistical methods to analyze data received through an online questionnaire. Results: The results suggest gender influences the views of employers to hire individuals in recovery. Women are more likely to hire individuals in recovery than men. Additionally, levels of concern among employers vary across industries displaying a likelihood of employers to hire individuals in recovery dependent on the extent of needs. Conclusion: The findings help illuminate the employability of this unique population and also develop a better understanding of the characteristics of prospective employers who are willing to hire individuals in addiction recovery

Motility of small nematodes in disordered wet granular media

The motility of the worm nematode \textit{Caenorhabditis elegans} is investigated in shallow, wet granular media as a function of particle size dispersity and area density ($\phi$). Surprisingly, we find that the nematode's propulsion speed is enhanced by the presence of particles in a fluid and is nearly independent of area density. The undulation speed, often used to differentiate locomotion gaits, is significantly affected by the bulk material properties of wet mono- and polydisperse granular media for $\phi \geq 0.55$. This difference is characterized by a change in the nematode's waveform from swimming to crawling in dense polydisperse media \textit{only}. This change highlights the organism's adaptability to subtle differences in local structure and response between monodisperse and polydisperse media

Zoom in at African Country level: Potential Climate Induced Changes in Areas of Suitability for Survival of Malaria Vectors

Predicting anopheles vectors’ population densities and boundary shifts is crucial in preparing for malaria risks and unanticipated outbreaks. Although shifts in the distribution and boundaries of the major malaria vectors (Anopheles gambiae s.s. and An. arabiensis) across Africa have been predicted, quantified areas of absolute change in zone of suitability for their survival have not been defined. In this study, we have quantified areas of absolute change conducive for the establishment and survival of these vectors, per African country, under two climate change scenarios and based on our findings, highlight practical measures for effective malaria control in the face of changing climatic patterns. We develop a model using CLIMEX simulation to estimate the potential geographical distribution and seasonal abundance of these malaria vectors in relation to climatic factors 9temperature, rainfall and relative humidity). The model yielded an eco climatic index (EI) describing the total favorable geographical locations for the species. The EI value were classified and exposed to a GIS package. Using ArcGIS, the EI shape points clipped to the extent of Africa and then converted to a raster layer using inverse Distance Weighted (IDW) interpolation method. Generated maps wre then transformed into polygon-based geo-referenced data set and areas computed and expressed in square kilometers (km2). Five classes of EI were derived indicating the level of survivorship of these malaria vectors. The proportion of areas increasing or decreasing in level of survival of these malaria vectors will be more pronounced in eastern and southern African countries than those in western Africa. Angola, Ethiopia, Kenya, Mozambique, Tanzania, South Africa and Zambia appear most likely to be affected in terms of absolute change of malaria vectors suitability zones under the selected climate change scenarios. The potential shifts of these malaria vectors have implications for human exposure to malaria, as recrudescence of the disease is likely to be recorded in several new areas and regions. Therefore, the need to develop, compile and share malaria preventive measures, which can be adapted to different climatic scenarios, remains crucial. \u

An Evaluation of a Maternal Health and Extreme Heat Exposure Training

Growing empirical evidence documents the potential risk of extreme heat exposure to pregnant individuals. These risks include adverse birth outcomes, such as preterm birth and low birth weight. Climate change will exacerbate extreme heat exposures to a large portion of the global population, and pregnant individuals need to understand the risks and protective measures needed. Maternal health workers are a key mechanism for conveying this information to pregnant individuals. The authors assess a training of maternal health workers in El Paso, Texas, through two research instruments. First, eight maternal health workers completed an educational workshop and consented to participation; pre- and post-test workshop data are reported. Second, and subsequent to the workshop, a focus group was undertaken with six maternal health workers; directed content analysis was used to synthesize and report patterns from this qualitative data. Assessments indicated that a training session can improve provider knowledge of maternal heat–health risks and can encourage providers to discuss heat risks with patients/clients. This pilot project offered an approach to raise awareness of extreme heat among maternal health workers. The authors encourage the development of similar trainings in other communities to improve the safety of pregnant individuals in warm regions and areas experiencing extreme heat