scholarly journals Hazards and Future Improvements to HI Surveys

1997 ◽  
Vol 14 (1) ◽  
pp. 96-98 ◽  
Author(s):  
J. Richard Fisher
Keyword(s):  
Phased Array ◽  
Substantial Improvement ◽  
Antenna Efficiency ◽  
Astronomical Observations ◽  
Major Increase ◽  
The Impact ◽  
Phased Array Feeds

AbstractMost radio astronomical observations are affected to some degree by man-made and natural interference. There are a few avoidance techniques that can reduce the impact of interference on the survey, but we must make quite significant advances in the understanding of our antennas and receivers and the interference itself before a substantial improvement can be expected. A major increase in the efficiency of future surveys will likely come from phased-array feeds, which have the potential for much closer beam spacings, greater antenna efficiency, and wider fields of view than current independent-feed arrays.

scholarly journals A Tutorial on Optical Feeding of Millimeter-Wave Phased Array Antennas for Communication Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-22 ◽  
Author(s):  
Ivan Aldaya ◽  
Gabriel Campuzano ◽  
Gerardo Castañón ◽  
Alejandro Aragón-Zavala
Keyword(s):  
Millimeter Wave ◽  
High Speed ◽  
Phased Array ◽  
Path Loss ◽  
High Gain ◽  
Interference Avoidance ◽  
Amplitude Control ◽  
Phased Array Antennas ◽  
Array Antennas ◽  
The Impact

Given the interference avoidance capacity, high gain, and dynamical reconfigurability, phased array antennas (PAAs) have emerged as a key enabling technology for future broadband mobile applications. This is especially important at millimeter-wave (mm-wave) frequencies, where the high power consumption and significant path loss impose serious range constraints. However, at mm-wave frequencies the phase and amplitude control of the feeding currents of the PAA elements is not a trivial issue because electrical beamforming requires bulky devices and exhibits relatively narrow bandwidth. In order to overcome these limitations, different optical beamforming architectures have been presented. In this paper we review the basic principles of phased arrays and identify the main challenges, that is, integration of high-speed photodetectors with antenna elements and the efficient optical control of both amplitude and phase of the feeding current. After presenting the most important solutions found in the literature, we analyze the impact of the different noise sources on the PAA performance, giving some guidelines for the design of optically fed PAAs.

scholarly journals Coalescence Dynamics of Acoustically Levitated Droplets

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 343 ◽  
Author(s):  
Koji Hasegawa ◽  
Ayumu Watanabe ◽  
Akiko Kaneko ◽  
Yutaka Abe
Keyword(s):  
Sound Pressure ◽  
Phased Array ◽  
Phased Arrays ◽  
Industrial Applications ◽  
Acoustic Levitation ◽  
Droplet Dynamics ◽  
Levitated Droplets ◽  
Ultrasonic Phased Array ◽  
Velocity Information ◽  
The Impact

The contactless coalescence of a droplet is of paramount importance for physical and industrial applications. This paper describes a coalescence method to be used mid-air via acoustic levitation using an ultrasonic phased array system. Acoustic levitation using ultrasonic phased arrays provides promising lab-on-a-drop applications, such as transportation, coalescence, mixing, separation, evaporation, and extraction in a continuous operation. The mechanism of droplet coalescence in mid-air may be better understood by experimentally and numerically exploring the droplet dynamics immediately before the coalescence. In this study, water droplets were experimentally levitated, transported, and coalesced by controlled acoustic fields. We observed that the edges of droplets deformed and attracted each other immediately before the coalescence. Through image processing, the radii of curvature of the droplets were quantified and the pressure difference between the inside and outside a droplet was simulated to obtain the pressure and velocity information on the droplet’s surface. The results revealed that the sound pressure acting on the droplet clearly decreased before the impact of the droplets. This pressure on the droplets was quantitatively analyzed from the experimental data. Our experimental and numerical results provide deeper physical insights into contactless droplet manipulation for futuristic lab-on-a-drop applications.

scholarly journals Grid Dependency Study for the NASA Rotor 37 Compressor Blade

1997 ◽  
Author(s):  
Andrea Arnone ◽  
Ennio Carnevale ◽  
Michele Marconcini
Keyword(s):  
Total Pressure ◽  
Turbulence Modeling ◽  
Leading Edge ◽  
Substantial Improvement ◽  
Compressor Blade ◽  
Computational Domain ◽  
Temperature Ratio ◽  
Turbulent Transition ◽  
Total Temperature ◽  
The Impact

The NASA Rotor 37 has been computed by several authors in the last few years with relative success. The aim of this work is to present a systematic grid dependency study in order to quantify the amount of uncertainty that comes from the grid density. The computational domain is divided onto several regions (i.e. leading edge, trailing edge, shear layer …) and for each of them, the impact of the grid density is investigated. By means of this analysis, substantial improvement has been obtained in the prediction of efficiency and exit angle. On the contrary, the improvement achieved in total pressure and total temperature ratio is less remarkable. It is believed that only after a systematic grid dependency study can the contribution of turbulence modeling, laminar-turbulent transition, and boundary conditions be analyzed with success.

Evaluation of the impact from the discharge of treated sewage on the south-east Saronicos Gulf through mathematical water quality modelling

1999 ◽  
Vol 39 (8) ◽  
pp. 63-70
Author(s):  
C. Noutsopoulos ◽  
E. Gavalaki ◽  
A. Andreadakis
Keyword(s):  
Biological Treatment ◽  
Critical Factor ◽  
Field Measurements ◽  
Substantial Improvement ◽  
Disposal Site ◽  
The South ◽  
Treated Sewage ◽  
Limiting Nutrient ◽  
The Impact

The paper presents the results of a study of the impact caused by the discharge of treated sewage from the south-west Attiki area to the south-east coast of the Saronicos Gulf. The study involved the application of a eutrophication-dissolved oxygen model which, following validation on the basis of field measurements, was applied to predict the impact of three different biological treatment configurations, with and without nutrients removal, as well as three alternative disposal sites on the quality of the receiving waters. The simulation results show that nitrogen is the limiting nutrient and that its removal during treatment results in a substantial improvement of the quality of the recipient. The disposal site is a critical factor in the case of a biological treatment scheme exhibiting carbon removal, but it is of limited importance in the case of treatment systems with nitrogen removal.

The nexus of economic growth, priority sector lending and non-performing assets: case of Indian banking sector

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Dolly Gaur ◽  
Dipti Ranjan Mohapatra
Keyword(s):  
Economic Growth ◽  
Banking Sector ◽  
Dynamic Panel ◽  
Content Type ◽  
Generalized Methods Of Moments ◽  
Major Increase ◽  
Dynamic Panel Regression ◽  
Methods Of Moments ◽  
The Impact

PurposeIn recent years, the Indian banking sector is facing a major cause of concern in the form of Nonperforming Assets (NPA), and the priority sector lending (PSL) is generally recognized as the major factor contributing to it. Thus, the present study has been carried out with the objective of examining the relationship between priority sector lending and GDP growth. Thereafter, the role of PSL and certain other bank-specific, industry-specific and macroeconomic variables in determining NPA has been studied.Design/methodology/approachTaking a sample of 45 scheduled commercial banks, the study has been carried out for 14 years (2004–2018). Granger causality between PSL and GDP has been examined by applying the Dumitrescu-Hurlin test. For the purpose of investigating the impact of PSL and other determinants on NPA, both static and dynamic panel regression have been performed. Under the dynamic panel, system generalized methods of moments (S-GMM) approach has been followed.FindingsThe findings show that there exists a positive correlation and bidirectional causal relationship between PSL and GDP, which implies that PSL brings additional growth for the whole economy. In addition to it, PSL is found to be insignificant for the NPA ratio, and thus, it can be inferred that credit extended to government-specified sectors does not bring any major increase in the bad loan portfolio of banks.Practical implicationsThe policymakers and bank management can take a cue from the findings of this study to decrease the exposure to loan nonrepayment issue. The priority sectors are in need of formal credit for their growth, and since the rising population of the country can find employment in these sectors, banks should meet their credit needs while securing their position with regard to the NPA problem.Originality/valueThe issue of NPA determinants, and in particular, the contribution of priority sector lending in it has not been much explored for Indian banking sector. Also, the present study adds to the literature by using the causality approach for examining the importance of directed credit schemes for economic growth.

scholarly journals Impact of a Pharmacist-Driven Protocol to Improve Drug Allergy Documentation at a University Hospital

2013 ◽  
Vol 48 (4) ◽  
pp. 302-307 ◽  
Author(s):  
Christopher Burrell ◽  
Candy Tsourounis ◽  
David Quan ◽  
Vicki Jue ◽  
Eunice Tam ◽  
...  
Keyword(s):  
Drug Allergy ◽  
Age Groups ◽  
Substantial Improvement ◽  
University Hospital ◽  
Order Entry ◽  
Post Intervention ◽  
Pediatric Services ◽  
Physician Order Entry ◽  
The Impact

Background An internal evaluation of the inpatient pharmacy order entry database ( WORx) at a university hospital revealed that the nature of the reaction was documented for only 47% of patients with reported drug allergies/intolerance. Insufficient documentation of drug allergy/intolerance may result in administration of drugs that should not be prescribed. Similarly, valuable agents that should be used may not be prescribed due to an unnecessary fear of adverse drug reaction. More complete description of drug allergy/intolerance may result in more correct prescribing of medications. Objective Evaluate the impact of a pharmacist-driven protocol on the quality of drug allergy/intolerance documentation. Methods Four pre-intervention evaluations were conducted every 2 weeks documenting the completeness of drug allergy/intolerance information in the pharmacy order entry database. One week following the implementation of a pharmacist-driven protocol intended to improve the completeness of drug allergy/intolerance information, a series of 4 postintervention evaluations was repeated. Proportional analysis of pre- and postinterventional data was performed to evaluate the effectiveness of the intervention. Results A total of 1,686 allergies from 2,174 patients were reviewed pre and post intervention. The frequency of complete drug allergy/intolerance documentation pre intervention was 52% to 62%. Following implementation of the hospitalwide, pharmacist-driven protocol, this rate increased to 60% to 76%. Pediatric services demonstrated the most substantial improvement, increasing from 53% to 79% to 67% to 93%. Blank reaction fields decreased by 10% in both age groups. Conclusion A pharmacy-driven initiative intended to improve the completeness of drug allergy/intolerance documentation was associated with modest success. Other mechanisms, including electronic health record systems with computerized physician order entry and decision support, are needed to improve the completeness of drug allergy/intolerance information.

scholarly journals PAFINDER – Searching for FRBs and pulsars using Phased Array Feeds

2017 ◽  
Vol 13 (S337) ◽  
pp. 370-371
Author(s):  
Mateusz Malenta ◽  
Ewan Barr ◽  
Aaron Chippendale ◽  
Xinping Deng ◽  
Daniel George ◽  
...  
Keyword(s):  
Real Time ◽  
Radio Telescope ◽  
Phased Array ◽  
Single Pulse ◽  
Radio Bursts ◽  
Pulse Detection ◽  
Phased Array Feeds

AbstractThe challenges of detecting and localising Fast Radio Bursts in real time can be met with the use of Phased Array Feeds. One such system, capable of creating up to 36 simultaneous beams, is currently being commissioned at the Effelsberg radio telescope in Germany following testing at the 64 m Parkes radio telescope. The PAFINDER (Phased Array Feed FRB Finder) pipeline will be used with this receiver to enable real–time single–pulse detection and localisation.

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