Total dose effects on negative voltage regulator

Abstract Functional failure at low dose level (4 Krad(Si)) on voltage regulators (LM137) from different manufacturers are analysed. Dose rate effects on parts hardness are evaluated, showing that lowering the dose rate degrade more the ICs in the range 55 rad(Si)/s-0,s rad(Si)/s A failure mechanism is proposed, mainly based on circuit analysis, voltage contrast measurements, local irradiation and local electrical measurements with probe station. A spice simulation was performed, providing quantitative informations on the degradation. In the light of such a failure analysis and dose rate Pagure (Saclay, France) panoramic Cobalt60 source of 20 000 Ci located few kilometres away from VBlizy plant. Remote testing were performed in VBlizy using LTS 2020 automatic tester from Analog Devices, Digital Signal Analyser DSA601 from Tekmnic and HP4172 from Helwett Packard. Delay between irradiation and remote testing is kept below one hour. Local irradiation are performed using scanning transmission electron microscope JEOL JSM840 with electron energy up to 40 Kev. Contrast voltage potential measurement were carried out using a IDS Shlumberger tester. Probing measurements were performed using Wentworth probe station MP900 and HP4145 from Helwett Packard. effects, practical implications on radiation assurance are discussed. FAILURE DESCRIPTION I. INTRODUCTION Bipolar linear ICs are usually known as quite hard parts regarding Total Dose effects, with typical dose hardness in the range 50 to 100 Krad(Si). Such a postulate comes mainly from the relative intrinsic high hardness of bipolar transistor and passive devices. The problem is that bipolar transistors and passive elements used in linear ICs are not similar to the well known elemental structures. Because of integration constraint and in order to minimise the number of mask steps during IC processing, PNP transistors are often lateral ones. Such a type of transistor is already known as Total Ionizing Dose (TID) sensitiveIl1. When using such a sensitive structure in critical function of linear IC, loss of functionality can be foreseen, as already predicted by Johnston 2. In this paper, we will focus on negative voltage regulator (LM137 type) from 4 different manufacturers. We will analyse the degradation mode, based on different test methods. LM137 is a three terminal adjustable output negative voltage regulator. Reference voltage of -1.250V can be delivered for input voltage (referred to output voltage) ranging from -4.2% to -41.25V. The 137 circuit, shown in figure 1, consists in start up circuit, intemal comparator, band gap reference, power output stage and prowtion circuitry. ILEXPERIMENTAL PROCEDUR

On the Nature of the Frontal Zone of the Choctawhatchee Bay Plume in the Gulf of Mexico

River plumes often feature turbulent processes in the frontal zone and interfacial region at base of the plume, which ultimately impact spreading and mixing rates with the ambient coastal ocean. The degree to which these processes govern overall plume mixing is yet to be quantified with microstructure observations. A field campaign was conducted in a river plume in the northeast Gulf of Mexico in December 2013, in order to assess mixing processes that could potentially impact transport and dispersion of surface material near coastal regions. Current velocity, density, and Turbulent Kinetic Energy Values, ε, were obtained using an Acoustic Doppler Current Profiler (ADCP), a Conductivity Temperature Depth (CTD) profiler, a Vertical Microstructure Profiler (VMP), and two Acoustic Doppler Velocimeters (ADVs). The frontal region contained ε values on the order of 10−5 m2 s−3, which were markedly larger than in the ambient water beneath (O 10−9 m2s−3). An energetic wake of moderate ε values (O 10−6 m2 s−3) was observed trailing the frontal edge. The interfacial region of an interior section of the plume featured opposing horizontal velocities and a ε value on the order of 10−6 m2 s−3. A simplified mixing budget was used under significant assumptions to compare contributions from wind, tides, and frontal regions of the plume. The results from this order of magnitude analysis indicated that frontal processes (59%) dominated in overall mixing. This emphasizes the importance of adequate parameterization of river plume frontal processes in coastal predictive models

Ocean convergence and the dispersion of flotsam

Floating oil, plastics, and marine organisms are continually redistributed by ocean surface currents. Prediction of their resulting distribution on the surface is a fundamental, long-standing, and practically important problem. The dominant paradigm is dispersion within the dynamical context of a nondivergent flow: objects initially close together will on average spread apart but the area of surface patches of material does not change. Although this paradigm is likely valid at mesoscales, larger than 100 km in horizontal scale, recent theoretical studies of submesoscales (less than ∼10 km) predict strong surface convergences and downwelling associated with horizontal density fronts and cyclonic vortices. Here we show that such structures can dramatically concentrate floating material. More than half of an array of ∼200 surface drifters covering ∼20 × 20 km2 converged into a 60 × 60 m region within a week, a factor of more than 105 decrease in area, before slowly dispersing. As predicted, the convergence occurred at density fronts and with cyclonic vorticity. A zipperlike structure may play an important role. Cyclonic vorticity and vertical velocity reached 0.001 s−1 and 0.01 ms−1, respectively, which is much larger than usually inferred. This suggests a paradigm in which nearby objects form submesoscale clusters, and these clusters then spread apart. Together, these effects set both the overall extent and the finescale texture of a patch of floating material. Material concentrated at submesoscale convergences can create unique communities of organisms, amplify impacts of toxic material, and create opportunities to more efficiently recover such material

Ocean convergence and the dispersion of flotsam

Floating oil, plastics, and marine organisms are continually redistributed by ocean surface currents. Prediction of their resulting distribution on the surface is a fundamental, long-standing, and practically important problem. The dominant paradigm is dispersion within the dynamical context of a nondivergent flow: objects initially close together will on average spread apart but the area of surface patches of material does not change. Although this paradigm is likely valid at mesoscales, larger than 100 km in horizontal scale, recent theoretical studies of submesoscales (less than ∼10 km) predict strong surface convergences and downwelling associated with horizontal density fronts and cyclonic vortices. Here we show that such structures can dramatically concentrate floating material. More than half of an array of ∼200 surface drifters covering ∼20 × 20 km2 converged into a 60 × 60 m region within a week, a factor of more than 105 decrease in area, before slowly dispersing. As predicted, the convergence occurred at density fronts and with cyclonic vorticity. A zipperlike structure may play an important role. Cyclonic vorticity and vertical velocity reached 0.001 s−1 and 0.01 ms−1, respectively, which is much larger than usually inferred. This suggests a paradigm in which nearby objects form submesoscale clusters, and these clusters then spread apart. Together, these effects set both the overall extent and the finescale texture of a patch of floating material. Material concentrated at submesoscale convergences can create unique communities of organisms, amplify impacts of toxic material, and create opportunities to more efficiently recover such material

Data for: Spectral characteristics of gravity-capillary waves, with connections to wave growth and microbreaking

In order to improve our understanding of physical air-sea interaction, it is essential to better describe the short-scale ocean wave response to wind forcing. This is particularly true for waves which are small enough to evade observation by traditional buoy and point-based gauge measurements but large enough to appreciably alter the transfer of momentum between atmosphere and ocean. Such waves are restored to equilibrium both by the earth’s gravity and air-sea surface tension, hence the classification as “gravity-capillary”. Radar remote sensing techniques depend greatly upon these waves in order to extract useful physical parameters from afar. Despite this importance, field observations of gravity-capillary wave characteristics are uncommon and vary from study to study. Furthermore, leading-edge model wavenumber spectra generally do not match each other in shape or important spectral parameters. Here we present an extended analysis of short wave data collected via a polarimetric camera aboard Research Platform (R/P) FLoating Instrument Platform (FLIP) in the Santa Barbara Channel. Our wavenumber saturation spectra show the emergence of a peak in the gravity-capillary subrange at low wind forcing magnitude (u*~0.045 m/s), consistent with critical wave growth in air-side stability theory. This is accompanied by a sharp increase in gravity-capillary-scale wave slope variance, a phenomenon that was previously only observed in the laboratory. Finally, the effects of microbreaking on wave spectral characteristics are discussed

Anatomía topográfica del asterion

Introducción. Las referencias anatómicas que permiten ubicar los senos venosos durante los abordajes de fosa posterior, son de utilidad para el neurocirujano. El asterion es usado como referencia para localizar cl seno transverso (ST). Material y método. Se utilizaron 50 hemicráneos de cadáveres adultos. Se estudió la relación del asterion con el ST, la vena emisaria mastoidea (VEM), la cresta suprameatal y el inion. Resultados. Se identificó el asterion en 49 casos. En el 87.8% de las piezas, se situó a la altura del seno transverso. El 72.2% se ubicó sobre el propio seno y el 27.8% sobre su codo. Si se traza una línea desde la cresta suprameatal al inion, el asterion se ubica por debajo de esta línea en el 88% de los casos. El foramen de la VEM se identificó en 46 oportunidades, en el 36% fue doble. Discusión y conclusiones. Según nuestros datos y los de otros autores, el orificio de trépano debe situarse por debajo y algo detrás del asterion para evitar la lesión del seno transverso

Cultivar híbrido de tomate "INIA Frontera" (HT72).

RESUMEN: "INIA Frontera" es un híbrido de tomate redondo indeterminado, seleccionado en Uruguay en condiciones de invernadero. Es un cultivar híbrido de tomate obtenido por INIA en el marco del convenio INIA-Agrocinco

Using ship-deployed high-endurance unmanned aerial vehicles for the study of ocean surface and atmospheric boundary layer processes

Unmanned aerial vehicles (UAVs) are proving to be an important modern sensing platform that supplement the sensing capabilities from platforms such as satellites, aircraft, research vessels, moorings, and gliders. UAVs, like satellites and aircraft can provide a synoptic view of a relatively large area. However, the coarse resolution provided by satellites and the operational limitations of manned aircraft has motivated the development of unmanned systems. UAVs offer unparalleled flexibility of tasking; for example, low altitude flight and slow airspeed allow for the characterization of a wide variety of geophysical phenomena at the ocean surface and in the marine atmospheric boundary layer. Here, we present the development of cutting-edge payload instrumentation for UAVs that provides a new capability for ship-deployed operations to capture a unique, high resolution spatial and temporal variability of the changing air-sea interaction processes than was previously possible. The modular design of the base payload means that new instruments can be incorporated into new research proposals that may include new instruments for expanded use of the payloads as a long-term research facility. Additionally, we implement a novel capability for vertical take-off and landing (VTOL) from research vessels. This VTOL capability is safer and requires less logistical support than previous ship-deployed systems. The payloads developed include thermal infrared, visible broadband and hyperspectral, and near-infrared hyperspectral high-resolution imaging. Additional capabilities include quantification of the longwave and shortwave hemispheric radiation budget (up- and down-welling) as well as direct air-sea turbulent fluxes. Finally, a UAV-deployed dropsonde-microbuoy was developed in order to profile the temperature, pressure and humidity of the atmosphere and the temperature and salinity of the near-surface ocean. These technological advancements provide the next generation of instrumentation capability for UAVs. When deployed from research vessels, UAVs will provide a transformational science prism unequaled using 1-D data snapshots from ships or moorings alone