Free-field propagation of high intensity noise

Research on high intensity (finite amplitude) acoustic waves shows that nonlinear distortion effects generally result in a shift of energy to higher frequencies. The higher intensities associated with supersonic jets would therefore indicate that high frequency enhancement of the spectrum should occur, resulting in the differences observed between subsonic and supersonic jets. A 10,000 acoustic watt source installed in an anechoic chamber generates sound levels such that acoustic shocks are readily observable. Dual frequency excitation of the source produces a strong parametric effect with a difference frequency comparable in level to the primary frequency. The test set up and recording equipment being used to determine the finite amplitude noise representative of an actual supersonic jet are described as well as the development of a computer program based on Burger's equation. The spectra of 1/2 octave band, 1 kHz sine wave, and dual frequency input and output are presented in graphs along with waveforms at Z = .025, 0.1, and 1.0

Optimierung einer Batch-Destillationskolonne unter Unsicherheiten basierend auf Messungen

C. Welz, B. Srinivasan, D. Bonvin Laboratoire d’Automatique Ecole Polytechnique Fédérale de Lausanne CH-1015 Lausanne, Schweiz O. Naef Département de Chimie Ecole d’Ingénieurs de Fribourg CH-1705 Fribourg, Schweiz Optimierung einer Batch-Destillationskolonne unter Unsicherheiten basierend auf Messungen Das Ziel der dynamischen Optimierung von binären Batch-Destillationskolonnen ist die Maximierung der Destillatmenge am Ende einer Charge bei gleichzeitiger Erfüllung der Endpunktbedingung für die Reinheit des Destillats. Das optimale Steuerungsprofil für das interne Rücklaufverhältnis (0 ≤ r ≤ 1) wird durch 2 Intervalle angenähert: 1) Anlaufphase mit vollem Rücklauf (r = 1), 2) Destillationsphase zur Produktion des Destillats (0 ≤ r ≤ 1). I m Fall von Prozessunsicherheiten muss eine konservative und suboptimale Prozessführungsstrategie gewählt werden, um die Endpunktbedingung zu erfüllen. Anstelle einer konservativen Strategie schlägt dieser Beitrag die Implementierung der notwendigen Optimalitätsbedingungen vor, die aus Rand- und SensibilitätsBedingungen bestehen. Entscheidend für das gegebene Optimierungsproblem ist es, d i e Randbedingungen zu erfüllen, insbesondere die Endpunktbedingung. Die Endpunktbedingung für die Reinheit des Destillats wird unter Verwendung von Messungen aktiv gehalten. Dies kann während einer Charge durch die Verfolgung eines Referenzprofils für die Reinheit des Destillats realisiert werden. Anstatt ein Modell zu aktualisieren, welches die Endpunktbedingung während der Destillation voraussagt, wird das System durch V e r f o l g u n g des Referenzprofils zu der Endpunktbedingung geführt. Dieses R e f e r e n z p r o f i l wird mit Hilfe eines Tendenzmodells des Systems bestimmt. U n s i c h e r h e i t e n in der Verdampfungsrate werden durch eine Vorregelung in Abhängigkeit von der Destillatmenge kompensiert, welche den Fortschritt der Destillation charakterisiert. Die Methode ist in der Lage, die Konservativität zu reduzieren und die Produktivität u n m i t t e l b a r zu steigern. Abbildung 1 zeigt die Verfolgung eines linearen Referenzprofils für die Reinheit des Destillats in einer Kolonne im Labormaßstab. Gegenüber einer suboptimalen Fahrweise mit konstanter Destillatzusammensetzung kann der Ertrag dabei um 11% gesteigert werden. Abbildung 1: Verfolgung einer Referenz für die Destillatzusammensetzung mit dem Ziel, die Endpunktbedingung zu erfüllen

Determination of mercury in airborne particulate matter collected on glass fiber filters using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sampling

A study has been undertaken to assess the capability of high-resolution continuum source graphite furnace atomic absorption spectrometry for the determination of mercury in airborne particulate matter (APM) collected on glass fiber filters using direct solid sampling. The main Hg absorption line at 253.652 nm was used for all determinations. The certified reference material NIST SRM 1648 (Urban Particulate Matter) was used to check the accuracy of the method, and good agreement was obtained between published and determined values. The characteristic mass was 22 pg Hg. The limit of detection (3σ), based on ten atomizations of an unexposed filter, was 40 ng g- 1, corresponding to 0.12 ng m- 3 in the air for a typical air volume of 1440 m3 collected within 24 h. The limit of quantification was 150 ng g-1, equivalent to 0.41 ng m-3 in the air. The repeatability of measurements was better than 17% RSD (n = 5). Mercury concentrations found in filter samples loaded with APM collected in Buenos Aires, Argentina, were between < 40 ng g-1 and 381 ± 24 ng g-1. These values correspond to a mercury concentration in the air between < 0.12 ng m-3 and 1.47 ± 0.09 ng m-3. The proposed procedure was found to be simple, fast and reliable, and suitable as a screening procedure for the determination of mercury in APM samples.Fil: Araujo, Rennan G. O.. Universidade Federal de Santa Catarina; BrasilFil: Vignola, Fabíola. Universidade Federal de Santa Catarina; BrasilFil: Castilho, Ivan N. B.. Universidade Federal de Santa Catarina; BrasilFil: Borges, Daniel L. G.. Universidade Federal de Santa Catarina; Brasil. Universidade Federal da Bahia; BrasilFil: Welz, Bernhard. Universidade Federal de Santa Catarina; Brasil. Universidade Federal da Bahia; BrasilFil: Vale, Maria Goreti R.. Universidade Federal do Rio Grande do Sul; Brasil. Universidade Federal da Bahia; BrasilFil: Smichowski, Patricia Nora. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ferreira, Sérgio L. C.. Universidade Federal da Bahia; BrasilFil: Becker Ross, Helmut. Leibniz-Institut für Analytische Wissenschaften; Alemani

A Parallel PC-based Visible Human Slice WEB server

Visualization of 3D tomographic images by slicing, i.e. by intersecting a 3D tomographic image with a plane having any desired position and orientation is a tool of choice both for learning and for diagnosis purposes. In this project, a parallel Visible Human Slice Web server has been developed, which offers to any Web client the capability of interactively specifying the exact position and orientation of a desired slice and of requesting and obtaining that slice from a 3D tomographic volume, made of either CT, MRI or cryosection images (digital color photographs of cross-sections). For interactive slice position and orientation, a miniature 3D version of the full image is used

The visible human slice Web server: a first assessment

The visible human slice server started offering its slicing services at the end of June 1998. From that date until the end of May, more than 280000 slices were extracted from the Visible Man, by laymen interested in anatomy, by students and by specialists. The Slice Server is based one Bi-Pentium PC and 16 disks. It is a scaled down version of a powerful parallel server comprising 5 Bi-Pentium Pro PCs and 60 disks. The parallel server program was created thanks to a computer-aided parallelization framework, which takes over the task of creating a multithreaded pipelined parallel program from a high-level parallel program description. On the full blown architecture, the parallel program enables the extraction and resampling of up to 5 color slices per second. Extracting 5 slice/s requires to access the disks and extract subvolumes of the Visible Human at an aggregate throughput of 105 MB/s. The publicly accessible server enables to extract slices having any orientation. The slice position and orientation can either be specified for each slice separately or as a position and orientation offered by a Java applet and possible future improvements. In the very near future, the Web Slice Server will offer additional services, such as the possibility to extract ruled surfaces and to extract animations incorporating slices perpendicular to a user defined trajector

Major and minor genes for stimulation of striga hermonthica seed germination in sorghum, and interaction with different striga populations

The parasitic angiosperms Striga hermonthica (Del.) Benth. and S. asiatica (L.) Kuntze severely constrain cereal production in sub-Saharan Africa. A resistance mechanism to these root parasites in sorghum [Sorghum bicolor (L.) Moench] is low exudation of striga seed germination stimulants. The trait is controlled by a single recessive gene in the sorghum x S. asiatica interaction, but information is lacking for S. hermonthica. Objectives of this investigation were to study the inheritance of stimulation of S. hermonthica seed germination in three F2 and two F3:5 recombinant inbred populations of sorghum, and to determine the effects of striga populations from Mali, Niger, and Kenya on the effectiveness of the low-stimulant character. An agar-gel assay was employed for this purpose. In this laboratory assay, the maximal distance between sorghum rootlets and germinated striga seed ("maximal germination distance") reflects the magnitude of germination stimulation. Bimodal frequency distributions supported the hypothesis of one recessive gene with a major effect for low maximal germination distance in progenies from crosses of low-stimulant lines (Framida, IS 9830) with a high-stimulant line (E 36-1), tested with striga from Mali or Niger. However, low- versus high-stimulant classes were not always clearly distinct, indicating that additional minor genes modified maximal germination distance in the progenies. The Kenyan striga population led to higher maximal germination distances and larger overlap of low- and high-stimulant classes than striga from Mali or Niger. Minor genes seemed therefore more important with Kenyan striga seed. The general involvement of minor genes in stimulating S. hermonthica seed germination was also evident from the heritable, quantitative variation observed in F3:5 lines derived from a cross of the high-stimulant lines N 13 and E 36-1. Because of the higher sensitivity of Kenyan striga to germination stimulation, the low-stimulant character may be less effective in Kenyan fields

Uptake of home-based voluntary HIV testing in sub-Saharan Africa: a systematic review and meta-analysis

Improving access to HIV testing is a key priority in scaling up HIV treatment and prevention services. Home-based voluntary counselling and testing (HBT) as an approach to delivering wide-scale HIV testing is explored here

Utility of indirect and direct selection traits for improving Striga resistance in two sorghum recombinant inbred populations

Breeding of sorghum (Sorghum bicolor L. Moench) for resistance to the parasitic weed Striga hermonthica (Del.) Benth. has been hampered by the difficulty of evaluating host resistance in the field and lack of reliable screening techniques. Therefore, we investigated the value of various indirect and direct measures of Striga resistance as selection traits. Two sorghum recombinant inbred populations of 226 F3:5 lines each were developed from the crosses (1) IS 9830 × E 36-1 and (2) N 13 × E 36-1. Striga-resistant line IS 9830 is characterized by low stimulation of Striga seed germination, whereas Striga-susceptible line E 36-1 produces germination stimulants in abundance. Line N 13 possesses "mechanical" resistance and probably also an antibiosis mechanism. Resistance was assessed in 1997 and 1998 using in vitro agar-gel assays with Striga seeds from Kenya, Mali, and Niger, pot trials in the respective three countries, and field experiments in Kenya and Mali. The agar-gel assay proved to be a useful, precise and fast indirect selection method to screen for sorghum entries with the low-stimulant character. However, correlation analysis showed that this resistance mechanism was ineffective in some environments, especially in Kenya, pointing to the necessity of field evaluation. Because of low heritability estimates and moderate to low correlations to Striga resistance under field conditions, pot screening appeared to be of limited use in breeding programs. The field trials confirmed the effectiveness of several direct measures of Striga resistance in sorghum: emerged Striga counts, Striga severity index, and area under the Striga number or severity progress curves. A two-row plot field layout with an empty row between plots, coupled with artificial infestation of test rows, lattice design and six replications offered an improved screening procedure that achieved high heritability. Significant genotype × environment interactions in the field experiments stress the importance of multi-locational trials to achieve stable Striga resistance

Feeding the rural tourism strategy? Food and notions of place and identity

The humble rural cuisine has now been thrust at the forefront of economic development strategies. This conceptual paper is a contribution to a growing critical awareness of the operations of the food industry and helps to foster a critical understanding of how, if at all, local food and its associated culture can help sustain rural tourism particularly and rural communities generally. It is inspired by literature about the international political economy of food and the many experiences of local food development, and is aware of the contrast between the structure of the industry and the hopes associated with its practice on the ground. The paper thus argues that, beyond the glamour and hype, there are those who gain, as well as those who lose, from the current food fad. While it explains the causes of the contemporary craze with food, the paper also interrogates the naı¨ve expectations often placed in food as a motor of rural development, and as the panacea for struggling rural communities. The empirical data on which this chapter is based are drawn from 18 short chapters explaining the history of various “traditional dishes” from the islands of the broad North Atlantic that feature in a recent food publication.peer-reviewe

Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100x larger than during its dormant state. The X-ray flux one month after reactivation was at least 800x larger than during quiescence, and has been decaying exponentially on a 111+/-19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure