Experimental evaluation of the response of micro-channel plate detector to ions with 10s of MeV energies

The absolute calibration of a microchannel plate (MCP) assembly using a Thomson spectrometer for laser-driven ion beams is described. In order to obtain the response of the whole detection system to the particles’ impact, a slotted solid state nuclear track detector (CR-39) was installed in front of the MCP to record the ions simultaneously on both detectors. The response of the MCP (counts/particles) was measured for 5–58 MeV carbon ions and for protons in the energy range2–17.3 MeV. The response of the MCP detector is non-trivial when the stopping range of particles becomes larger than the thickness of the detector. Protons with energiesE>~ 10 MeV are energetic enough that they can pass through the MCP detector. Quantitative analysis of the pits formed in CR-39 and the signal generated in the MCP allowed to determine the MCP response to particles in this energy range. Moreover, a theoretical model allows to predict the response of MCP at even higher proton energies. This suggests that in this regime the MCP response is a slowly decreasing function of energy, consistently with the decrease of the deposited energy. These calibration data will enable particle spectra to be obtained in absolute terms over a broad energy range.

Eating from the same plate? Revisiting the role of labile carbon inputs in the soil food web

An increasing number of empirical studies are challenging the central fundamentals on which the classical soil food web model is built. This model assumes that bacteria consume labile substrates twice as fast as fungi, and that mycorrhizal fungi do not decompose organic matter. Here, we build on emerging evidence that points to significant consumption of labile C by fungi, and to the ability of ectomycorrhizal fungi to decompose organic matter, to show that labile C constitutes a major and presently underrated source of C for the soil food web. We use a simple model describing the dynamics of a recalcitrant and a labile C pool and their consumption by fungi and bacteria to show that fungal and bacterial populations can coexist in a stable state with large inputs into the labile C pool and a high fungal use of labile C. We propose a new conceptual model for the bottom trophic level of the soil food web, with organic C consisting of a continuous pool rather than two or three distinct pools, and saprotrophic fungi using substantial amounts of labile C. Incorporation of these concepts will increase our understanding of soil food web dynamics and functioning under changing conditions.

Finite Element Modeling of Spiral Frequency Steerable Acoustic Transducers (FSATs) for guided waves based Structural Health Monitoring of plate-like structures

Structural Health Monitoring (SHM) is an emerging area of research associated to improvement of maintainability and the safety of aerospace, civil and mechanical infrastructures by means of monitoring and damage detection. Guided wave structural testing method is an approach for health monitoring of plate-like structures using smart material piezoelectric transducers. Among many kinds of transducers, the ones that have beam steering feature can perform more accurate surface interrogation. A frequency steerable acoustic transducer (FSATs) is capable of beam steering by varying the input frequency and consequently can detect and localize damage in structures. Guided wave inspection is typically performed through phased arrays which feature a large number of piezoelectric transducers, complexity and limitations. To overcome the weight penalty, the complex circuity and maintenance concern associated with wiring a large number of transducers, new FSATs are proposed that present inherent directional capabilities when generating and sensing elastic waves. The first generation of Spiral FSAT has two main limitations. First, waves are excited or sensed in one direction and in the opposite one (180 ̊ ambiguity) and second, just a relatively rude approximation of the desired directivity has been attained. Second generation of Spiral FSAT is proposed to overcome the first generation limitations. The importance of simulation tools becomes higher when a new idea is proposed and starts to be developed. The shaped transducer concept, especially the second generation of spiral FSAT is a novel idea in guided waves based of Structural Health Monitoring systems, hence finding a simulation tool is a necessity to develop various design aspects of this innovative transducer. In this work, the numerical simulation of the 1st and 2nd generations of Spiral FSAT has been conducted to prove the directional capability of excited guided waves through a plate-like structure.

Managing Digitization Priorities with Metrics

This presentation was one of four during a Mid-Atlantic Regional Archives Conference presentation on April 15, 2016. Digitization of collections can help to improve internal workflows, make materials more accessible, and create new and engaging relationships with users. Laurie Gemmill Arp will discuss the LYRASIS Digitization Collaborative, created to assist institutions with their digitization needs, and how it has worked to help institutions increase connections with users. Robin Pike from the University of Maryland will discuss how they factor requests for access into selection for digitization and how they track the use of digitized materials. Laura Drake Davis of James Madison University will discuss the establishment of a formal digitization program, its impact on users, and the resulting increased use of their collections. Linda Tompkins-Baldwin will discuss Digital Maryland’s partnership with the Digital Public Library of America to provide access to archives held by institutions without a digitization program.

Managing Audiovisual Digitization

A synopsis and preparation presentation of a Society of American Archivists pre-conference workshop (workshop held on August 17, 2015.

TWO-PHASE HEAT TRANSFER MECHANISMS WITHIN PLATE HEAT EXCHANGERS: EXPERIMENTS AND MODELING

Two-phase flow heat exchangers have been shown to have very high efficiencies, but the lack of a dependable model and data precludes them from use in many cases. Herein a new method for the measurement of local convective heat transfer coefficients from the outside of a heat transferring wall has been developed, which results in accurate local measurements of heat flux during two-phase flow. This novel technique uses a chevron-pattern corrugated plate heat exchanger consisting of a specially machined Calcium Fluoride plate and the refrigerant HFE7100, with heat flux values up to 1 W cm-2 and flow rates up to 300 kg m-2s-1. As Calcium Fluoride is largely transparent to infra-red radiation, the measurement of the surface temperature of PHE that is in direct contact with the liquid is accomplished through use of a mid-range (3.0-5.1 µm) infra-red camera. The objective of this study is to develop, validate, and use a unique infrared thermometry method to quantify the heat transfer characteristics of flow boiling within different Plate Heat Exchanger geometries. This new method allows high spatial and temporal resolution measurements. Furthermore quasi-local pressure measurements enable us to characterize the performance of each geometry. Validation of this technique will be demonstrated by comparison to accepted single and two-phase data. The results can be used to come up with new heat transfer correlations and optimization tools for heat exchanger designers. The scientific contribution of this thesis is, to give PHE developers further tools to allow them to identify the heat transfer and pressure drop performance of any corrugated plate pattern directly without the need to account for typical error sources due to inlet and outlet distribution systems. Furthermore, the designers will now gain information on the local heat transfer distribution within one plate heat exchanger cell which will help to choose the correct corrugation geometry for a given task.

Microstructure and tensile properties of carbon-epoxy laminates produced by automated fibre placement: Influence of a caul plate on the effects of gap and overlap embedded defects

Automated fibre placement (AFP) enables the trajectory of unidirectional composite tape to be optimized, but laying down complex shapes with this technology can result in the introduction of defects. The aim of this experimental study is to investigate the influence of gaps and overlaps on the microstructure and tensile properties of carbon-epoxy laminates. First, a comparison between a hand-layup and AFP layup, draped and cured under the same conditions, shows equivalent microstructures and tensile properties. This provides the reference values for the study. Then, gap and overlap embedded defects (more or less severe) are introduced during manufacturing, on two cross-ply layups [(0°/(90°)5/0°] and [(90°/0°)2/90°]. Autoclave cure without a caul plate results in local thickness variation and microstructural changes which depend on the defect type. This has a strong influence on mechanical performance. Use of a caul plate avoids these variations and in this case embedded defects hardly affect tensile properties.

Comparison of High Q microresonators operating on a thin plate mode : the Lamé-mode

International audience

choose MyPlate : 10 tips to a great plate

Making food choices for a healthy lifestyle can be as simple as using these 10 Tips : balance calories, enjoy your food, but eat less, avoid oversized portions, foods to eat more often, make half your plate fruits and vegetables, switch to fat-free or low-fat (1%) milk, make half your grains whole grains, foods to eat less often, compare sodium in foods, drink water instead of sugary drinks.

On local flat-plate similarity in the hypersonic boundary layer,

Mode of access: Internet.

Contrat de Plan État-Région Bretagne. Relance de l'huître plate. Rapport d'avancement des travaux 1988.

Un contrat de Plan État-Région Bretagne a été signé en 1983 pour financer des recherches sur la période 1984-1988 dans le but de permettre la relance de l'élevage de l'huître plate, à la suite de la deuxième épizootie due à un protozaire, Bonamia ostreae. Ce rapport présente les travaux réalisés et les résultats acquis durant l'année 1988, dans les domaines de la pathologie (étude de la maladie et des mécanismes de défense des mollusques) de la génétique (recherche de souches résistantes), de l'épidémiologie descriptive et de la zootechnie.

Performance of Plate Type Heat Exchanger as Ammonia Condenser

In this study, I experimentally analyzed the performance of a commercial semi-welded plate type heat exchanger (PHE) for use with ammonia systems. I determined performance parameters such as overall heat transfer coefficient, capacity, and pressure drop of the semi-welded PHE. This was analyzed by varying different parameters which demonstrated changes in overall heat transfer coefficient, capacity, and pressure drop. Both water and ammonia flow rates to the semi-welded PHE were varied independently, and analyzed in order to understand how changes in flow rates affected performance. Inlet water temperature was also varied, in order to understand how raising condenser water inlet temperature would affect performance. Finally, pressure drop was monitored to better understand the performance limitations of the semi-welded PHE. Testing of the semi-welded will give insight as to the performance of the semi-welded PHE in a potential ocean thermal energy conversion system, and whether the semi-welded PHE is a viable choice for use as an ammonia condenser.

Calibración del rising plate meter para estimular la disponibilidad de materia seca en praderas mixtas lolium perenne-pennisetum clandestinum, en el municipio de Cota, Cundinamarca

Bogotá : Universidad de La Salle. Facultad de Ciencias Agropecuarias. Programa de Zootecnia