Transmission of sound through nonuniform circular ducts with compressible mean flows

An acoustic theory is developed to determine the sound transmission and attenuation through an infinite, hard-walled or lined, circular duct carrying compressible, sheared, mean flows and having a variable cross section. The theory is applicable to large as well as small axial variations, as long as the mean flow does not separate. Although the theory is described for circular ducts, it is applicable to other duct configurations - annular, two dimensional, and rectangular. The theory is described for the linear problem, but the technique is general and has the advantage of being applicable to the nonlinear case as well as the linear case. The technique is based on solving for the envelopes of the quasi-parallel acoustic modes that exist in the duct instead of solving for the actual wave. A computer program was developed. The mean flow model consists of a one dimensional flow in the core and a quarter-sine profile in the boundary layer. Results are presented for the reflection and transmission coefficients in ducts with varying slopes and carrying different mean flows

A wave-envelope of sound propagation in nonuniform circular ducts with compressible mean flows

An acoustic theory is developed to determine the sound transmission and attenuation through an infinite, hard-walled or lined circular duct carrying compressible, sheared, mean flows and having a variable cross section. The theory is applicable to large as well as small axial variations, as long as the mean flow does not separate. The technique is based on solving for the envelopes of the quasi-parallel acoustic modes that exist in the duct instead of solving for the actual wave, thereby reducing the computation time and the round-off error encountered in purely numerical techniques. The solution recovers the solution based on the method of multiple scales for slowly varying duct geometry. A computer program was developed based on the wave-envelope analysis for general mean flows. Results are presented for the reflection and transmission coefficients as well as the acoustic pressure distributions for a number of conditions: both straight and variable area ducts with and without liners and mean flows from very low to high subsonic speeds are considered

The Plasma Interaction Experiment (PIX) description and test program

The plasma interaction experiment (PIX) is a battery powered preprogrammed auxiliary payload on the LANDSAT-C launch. This experiment is part of a larger program to investigate space plasma interactions with spacecraft surfaces and components. The varying plasma densities encountered during available telemetry coverage periods are deemed sufficient to determine first order interactions between the space plasma environment and the biased experimental surfaces. The specific objectives of the PIX flight experiment are to measure the plasma coupling current and the negative voltage breakdown characteristics of a solar array segment and a gold plated steel disk. Measurements will be made over a range of surface voltages up to plus or minus kilovolt. The orbital environment will provide a range of plasma densities. The experimental surfaces will be voltage biased in a preprogrammed step sequence to optimize the data returned for each plasma region and for the available telemetry coverage

Sinteza, protuupalno, analgetsko i antikonvulzivno djelovanje 1,8-dihidro-1-aril-8-alkil pirazolo(3,4-b)indola

A series of 1,8-dihydro-1-aryl-8-alkyl pyrazolo(3,4-b)indoles 4a-j, 5a-j and 6a-j has been synthesized and tested for their anti-inflammatory and anticonvulsant activities. Formation of the pyrazoloindole derivatives was achieved by treating arylhydrazones of N-alkyl indole-3-carboxaldehydes 1a-j, 2a-j and 3a-j with ten times their mass of polyphosphoric acid as a condensing agent. The newly synthesized compounds were evaluated for their anti-inflammatory, analgesic and anticonvulsant activities compared to indomethacin, flufenamic acid and diazepam as positive controls. Detailed synthesis, spectroscopic and toxicity data are reported.Serija 1,8-dihidro-1-aril-8-alkil pirazolo(3,4-b)indola 4a-j, 5a-j i 6a-j sintetizirana je i testirana na protuupalno i antikonvulzivno djelovanje. Pirazolindol derivati pripravljeni su reakcijom arilhidrazona N-alkil indol-3-karboksaldehida 1a-j, 2a-j i 3a-j s deset puta većom masom polifosforne kiseline kao sredstva za kondenzaciju. Novosintetizirani spojevi testirani su na protuupalno, analgetsko i antikonvulzivno djelovanje i uspoređeni s djelovanjem indometacina, flufenaminske kiseline i diazepama. U radu su dati detaljni sintetski, spektroskopski i toksikološki podaci

Workplace Giving in Universities: A U.S. Case Study at Indiana University

The phenomenon of workplace giving is underexamined in the scholarly literature; philanthropic gifts by employees to their nonprofit employers have received less attention within national and transnational contexts. This study considered the association between university staff propensity toward “internal workplace giving” and donor characteristics, drawing on literature about organizational commitment and identification as a beginning for advancing theoretical understanding of employee–employer relationships and giving at both the micro-level and meso-level. The sample of 17,038 employees covered 3 years at Indiana University, an American, public, multicampus institution. Despite its specific national and cultural context, the study raises relevant issues about workplace giving. Relational and personal characteristics were found to be significant predictors for determining who donates; using these characteristics to predict giving levels, however, was less successful. The study anticipates a growing need for related research and provides direction for further methodological and theoretical approaches

Single shot cathode transverse momentum imaging in high brightness photoinjectors

In state of the art photoinjector electron sources, thermal emittance from photoemission dominates the final injector emittance. Therefore, low thermal emittance cathode developments and diagnostics are very important. Conventional thermal emittance measurements for the high gradient gun are time-consuming and thus thermal emittance is not measured as frequently as quantum efficiency during the lifetime of photocathodes, although both are important properties for the photoinjector optimizations. In this paper, a single shot measurement of photoemission transverse momentum, i.e., thermal emittance per rms laser spot size, is proposed for photocathode rf guns. By tuning the gun solenoid focusing, the electrons' transverse momenta at the cathode are imaged to a downstream screen, which enables a single shot measurement of both the rms value and the detailed spectra of the photoelectrons' transverse momenta. Both simulations and proof of principle experiments are reported

Secondary metabolites from Calotropis procera (Aiton)

Three new metabolites, 5-hydroxy-3,7-dimethoxyflavone-4′-O-β-glucopyranoside (1), 2β,19-epoxy-3β,14β-dihydroxy-19-methoxy-5α-card-20(22)-enolide (4) and β-anhydroepidigitoxigenin-3β-O-glucopyranoside (5), along with two known compounds, uzarigenine (2) and β-anhydroepidigitoxigenin (3), were isolated from Calotropis procera (Asclepiadaceae). The structure elucidation was accomplished mainly by nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric methods. To examine putative antimicrobial or cytotoxic activities, various bioassays were performed. Uzarigenine (2) demonstrated moderate cytotoxicity

A GIS–Integrated Wireless Sensors Network Tool for Water Risk Monitoring – Case of Khanh Hoa Water Supply and Sewerage Company, Vietnam

This paper investigates the feasibility of deploying a wireless sensor network (WSN) to monitor raw water quality at 2 major water treatment plants (WTPs) sites, operated by the The Khanh Hoa Water Supply and Sewerage Company (KHAWASSCO) in Vietnam: Canh Vo and Xuan Canh on the Cai River. The main aim is to propose a WSN for both WTPs which includes 2 clusters of sensors with 4 nodes each in order to monitor various parameters of water quality. Data management is integrated with a geographical information system (GIS) tool in order to provide a comprehensive spatio-temporal database in real time. This will assist decision makers in improving the management of the raw water quality at Cai River

Contact mechanics for soft robotic fingers: modeling and experimentation

Human fingers possess mechanical characteristics, which enable them to manipulate objects. In robotics, the study of soft fingertip materials for manipulation has been going on for a while; however, almost all previous researches have been carried on hemispherical shapes whereas this study concentrates on the use of hemicylindrical shapes. These shapes were found to be more resistant to elastic deformations for the same materials. The purpose of this work is to generate a modified nonlinear contact-mechanics theory for modeling soft fingertips, which is proposed as a power-law equation. The contact area of a hemicylindrical soft fingertip is proportional to the normal force raised to the power of γcy, which ranges from 0 to 1/2. Subsuming the Timoshenko and Goodier (S. P. Timoshenko and J. N. Goodier, Theory of Elasticity, 3rd ed. (McGraw-Hill, New York, 1970) pp. 414-420) linear contact theory for cylinders confirms the proposed power equation. We applied a weighted least-squares curve fitting to analyze the experimental data for different types of silicone (RTV 23, RTV 1701, and RTV 240). Our experimental results supported the proposed theoretical prediction. Results for human fingers and hemispherical soft fingers were also compare

Upcycling Used Garments to Recreate Sustainable Fashion Designs Treated by Soil Release Finishing

Upcycled garments can have that independent appeal. No matter whom the designer is or what styling options designers choose, these upcycled fashion garments and accessories are by nature one-of-a kind. Finishing of textile fabric is carried out to increase attractiveness and/or serviceability of the fabric. Different finishing treatments are available to get various effects, which add value to the basic textile material, which can be better solutions for sustainable fashion. The sustainable fashion was achieved to a certain extent by using available materials to its ultimate USAge, using waste material, recycling of the products, planning second life for the fashion product, slowing down the fashion etc. The main idea to do so is to develop more sustainable and responsible designs. This paper is not just about recycled clothes but about fashion, recycling, upcycling, adding value and uniqueness by the resulting one-of-a-kind design available for women to purchase in any retail store. Create nine designs using waste garments treated by soil release finishing agent as a source of sustainable fashionable designs