Olympus propagation studies in the US: Receiver development and the data acquisition system

Virginia Tech has developed two types of receivers to monitor the Olympus beacons, as well as a custom data acquisition system to store and display propagation data. Each of the receiver designs uses new hybrid analog/digital techniques. The data acquisition system uses a stand alone processor to collect and format the data for display and subsequent processing. The launch of the Olympus satellite with its coherent beacons offers new opportunities to study propagation effects at 12.5, 20, and 30 GHz. At Virginia Tech, the satellite is at 14 degrees in elevation, which allows us to measure low elevation angle effects. However, to make these measurements, a very accurate and stable measurement system is required. Virginia Tech has constructed a complex receiving system which monitors the Olympus beacons and all parameters associated with propagation research. In the current configuration, researchers have developed a receiver which frequency locks to the less fade susceptible 12.5 GHz beacon. Since all beacons on the satellite are driven from a single master oscillator, drift in the 12.5 GHz beacon implies corresponding drifts in the 20, and 30 GHz beacons. The receivers for the 20 and 30 GHz systems derive their frequency locking information from the 12.5 GHz system. This widens the dynamic range of the receivers and allows the receivers to maintain lock in severe fade conditions. In addition to monitoring the beacons, the sky noise is monitored with radiometers at each frequency. The radiometer output is used to set the clear air level for each beacon measurement. Researchers also measure the rain rate with several tipping bucket rain gauges placed along the propagation path

Many-core compiler fuzzing

We address the compiler correctness problem for many-core systems through novel applications of fuzz testing to OpenCL compilers. Focusing on two methods from prior work, random differential testing and testing via equivalence modulo inputs (EMI), we present several strategies for random generation of deterministic, communicating OpenCL kernels, and an injection mechanism that allows EMI testing to be applied to kernels that otherwise exhibit little or no dynamically-dead code. We use these methods to conduct a large, controlled testing campaign with respect to 21 OpenCL (device, compiler) configurations, covering a range of CPU, GPU, accelerator, FPGA and emulator implementations. Our study provides independent validation of claims in prior work related to the effectiveness of random differential testing and EMI testing, proposes novel methods for lifting these techniques to the many-core setting and reveals a significant number of OpenCL compiler bugs in commercial implementations

Alien Registration- Mckeeman, William C. (Calais, Washington County)

https://digitalmaine.com/alien_docs/2047/thumbnail.jp

Identifying fabrication defects of metal packaged fibre Bragg grating sensors for smart pre-stressing strands

Metal packaged fibre Bragg grating sensors have the potential to provide reliable measurements of temperature and strain in high stress environments for the purpose of structural health monitoring. However due to the induction brazing fabrication process a small percentage of sensors are found to have defective brazed joints. We demonstrate a defect identification procedure derived from the batch temperature calibration of fibre Bragg grating sensors for temperature and strain measurement, allowing defective sensors to be identified before installation. The procedure was demonstrated on a sample of twelve temperature sensors fabricated for a small-scale smart pre-stressing strand validation test

A comparison of brazed metal and epoxied fibre Bragg grating strain sensors under high strain regimes

Three different fibre Bragg grating strain sensors were tested for their suitability for measuring high strain. The sensor types were: a bare epoxied fibre Bragg grating, a standard fibre Bragg grating epoxied into a metal capillary and, finally, a metal coated fibre Bragg grating brazed into a metal capillary. The sensors were calibrated on a steel specimen up to 1400MPa (equivalent to 7.3mε). The results show that the bare epoxied Bragg grating and the metal packaged grating are suitable for measuring strains of this level

Helping the helpers: Tending to Kansas educators’ social-emotional needs and self-care during a pandemic

On a typical day, pre-COVID 19, educators are pulled in many directions, making hundreds, if not thousands, of quick decisions. Today those dynamics are heightened with varied and additional competing needs. However, what has not changed is the essential role of an educator. Caring for students in a time of such uncertainty seems critical. However, while there is serious and necessary demand for caring for the students and families, one population that is gravely being overlooked are the helpers. The educators. Less emphasis is being placed on the wellness and self-care of those who are offering those needed social-emotional supports. For a myriad of reasons, it is clear that emphasis must be placed on tending to the needs of Kansas educators’ well-being. In an effort to maintain educator passion and performance, messages around self-care, building social-emotionally competent classrooms and school climates are addressed

In-situ temperature calibration procedure for temperature and strain fibre Bragg grating sensors for monitoring pre-stressing strands

In this work, we demonstrate active and passive methods for in-situ temperature calibration of fibre Bragg grating strain and temperature sensors. The method is suitable for characterizing sensors which are already attached to the steel reinforcements of civil structures. The proposed method, which involves the use of active induction heating or passive room temperature fluctuations, can be implemented using portable equipment, is time efficient, and can be used to calibrate attached sensors on-site, rather than in lab conditions. Preliminary results of the induction heating calibration show good agreement with pre-calibrated temperature sensors. In-situ calibration of fibre strain sensors, attached to a prestressing strand is also successfully carried out

Wireless surface acoustic wave sensors for displacement and crack monitoring in concrete structures

In this work, we demonstrate that wireless surface acoustic wave devices can be used to monitor millimetre displacements in crack opening during the cyclic and static loading of reinforced concrete structures. Sensors were packaged to extend their gauge length and to protect them against brittle fracture, before being surface-mounted onto the tensioned surface of a concrete beam. The accuracy of measurements was verified using computational methods and optical-fibre strain sensors. After packaging, the displacement and temperature resolutions of the surface acoustic wave sensors were 10µm and 2 C respectively. With some further work, these devices could be retrofitted to existing concrete structures to facilitate wireless structural health monitoring

Metal-Packaged fibre Bragg grating strain sensors for surface mounting onto spalled concrete wind turbine foundations

In this work, we demonstrate preliminary results for a hermetically sealed, metal-packaged fibre Bragg grating strain sensor for monitoring existing concrete wind turbine foundations. As the sensor is bolted to the sub-surface of the concrete, it is suitable for mounting onto uneven, wet and degraded surfaces, which may be found in buried foundations. The sensor was able to provide reliable measurements of concrete beam strain during cyclic three- And four- point bend tests. The strain sensitivity of the prototype sensor is currently 10 % of that of commercial, epoxied fibre strain sensors

Dysfunction of Organic Anion Transporting Polypeptide 1a1 Alters Intestinal Bacteria and Bile Acid Metabolism in Mice

Organic anion transporting polypeptide 1a1 (Oatp1a1) is predominantly expressed in liver and is able to transport bile acids (BAs) in vitro. Male Oatp1a1-null mice have increased concentrations of taurodeoxycholic acid (TDCA), a secondary BA generated by intestinal bacteria, in both serum and livers. Therefore, in the present study, BA concentrations and intestinal bacteria in wild-type (WT) and Oatp1a1-null mice were quantified to investigate whether the increase of secondary BAs in Oatp1a1-null mice is due to alterations in intestinal bacteria. The data demonstrate that Oatp1a1-null mice : (1) have similar bile flow and BA concentrations in bile as WT mice; (2) have a markedly different BA composition in the intestinal contents, with a decrease in conjugated BAs and an increase in unconjugated BAs; (3) have BAs in the feces that are more deconjugated, desulfated, 7-dehydroxylated, 3-epimerized, and oxidized, but less 7-epimerized; (4) have 10-fold more bacteria in the small intestine, and 2-fold more bacteria in the large intestine which is majorly due to a 200% increase in Bacteroides and a 30% reduction in Firmicutes; and (5) have a different urinary excretion of bacteria-related metabolites than WT mice. In conclusion, the present study for the first time established that lack of a liver transporter (Oatp1a1) markedly alters the intestinal environment in mice, namely the bacteria composition