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Статті в журналах з теми "Direct current source"
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Zhu, W., N. Takano, K. H. Schoenbach, D. Guru, J. McLaren, J. Heberlein, R. May, and J. R. Cooper. "Direct current planar excimer source." Journal of Physics D: Applied Physics 40, no. 13 (June 15, 2007): 3896–906. http://dx.doi.org/10.1088/0022-3727/40/13/s09.
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Dudek, D., N. Bibinov, J. Engemann, and P. Awakowicz. "Direct current plasma jet needle source." Journal of Physics D: Applied Physics 40, no. 23 (November 16, 2007): 7367–71. http://dx.doi.org/10.1088/0022-3727/40/23/017.
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Smith, H. Vernon, Paul Allison, Carl Geisik, David R. Schmitt, J. David Schneider, and James E. Stelzer. "A direct‐current Penning surface‐plasma source." Review of Scientific Instruments 65, no. 4 (April 1994): 1176–78. http://dx.doi.org/10.1063/1.1145049.
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Vereshchago, E. N., and V. I. Kostyuchenko. "Instability of mode in circuit with capacity and electric arc supplied by direct current source." Paton Welding Journal 2014, no. 8 (August 28, 2014): 42–46. http://dx.doi.org/10.15407/tpwj2014.08.07.
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Dudnikov, V., C. W. Schmidt, R. Hren, and J. Wendt. "Direct current surface plasma source with high emission current density." Review of Scientific Instruments 73, no. 2 (February 2002): 989–91. http://dx.doi.org/10.1063/1.1431410.
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Tsukamoto, Osami, Yoshiaki Nagai, and Kazuhiro Imaie. "Direct Connected Multiple Current Source Converters for SMES system." IEEJ Transactions on Industry Applications 118, no. 9 (1998): 992–99. http://dx.doi.org/10.1541/ieejias.118.992.
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Posadowski, Witold M., and Zbigniew J. Radzimski. "Sustained self‐sputtering using a direct current magnetron source." Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 11, no. 6 (November 1993): 2980–84. http://dx.doi.org/10.1116/1.578679.
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Belchenko, Yu, I. Gusev, A. Khilchenko, A. Kvashnin, V. Rashchenko, A. Sanin, V. Savkin, and P. Zubarev. "Advanced direct current negative-ion source for accelerator use." Review of Scientific Instruments 77, no. 3 (March 2006): 03A527. http://dx.doi.org/10.1063/1.2170032.
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He, Chuan, Chang Bao Han, Guang Qin Gu, Tao Jiang, Bao Dong Chen, Zhen Liang Gao, and Zhong Lin Wang. "Hourglass Triboelectric Nanogenerator as a “Direct Current” Power Source." Advanced Energy Materials 7, no. 19 (June 9, 2017): 1700644. http://dx.doi.org/10.1002/aenm.201700644.
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Tsukamoto, Osami, Yoshiaki Nagai, and Kazuhiro Imaie. "Direct-connected multiple current-source converters for SMES system." Electrical Engineering in Japan 133, no. 1 (2000): 87–96. http://dx.doi.org/10.1002/1520-6416(200010)133:1<87::aid-eej9>3.0.co;2-9.
Повний текст джерелаДисертації з теми "Direct current source"
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Zhang, Yushu. "Multilevel voltage source converters in high voltage direct current transmission systems." Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25814.
Повний текст джерелаАнотація:
This research focuses on voltage source multilevel converters in high voltage direct current (HVDC) transmission systems. The first Voltage Source Converter based HVDC (VSC-HVDC) systems with series connected IGBTs in a two-level converter represented a solution to meet industrial and economical requirements but is associated with significant drawbacks such as high dv/dt and di/dt, high switching loss, and poor output voltage and current quality. To overcome these issues, the multilevel converter was proposed for HVDC application. The Modular Multilevel Converter (M2C) was the first multilevel converter to be commercially used in the power industry. In this thesis, the M2C is investigated mainly in terms of operating principle, capacitor size and capacitor voltage ripple, capacitor voltage balancing technique and modulation scheme. The results of this investigation show that the M2C offers the following features: improved efficiency, lower supporting voltage and current in the switching devices and low dv/dt. These features make the M2C suitable for HVDC systems. Two new operational principles and modulation strategies for a Hybrid Cascaded Multilevel Converter (HCMC) are proposed in this thesis. Both modulation schemes extend the modulation index linear range and improve the output waveform quality. This gives the HCMC a higher power density than any known multilevel converter topology for the same dc link voltage and switching device rating. Simulations for both types of multilevel converter (M2C and HCMC) are supported by practical results from scaled hardware laboratory converters. Mathematical analysis and calculation of conversion loss for both types of multilevel converter and for the conventional two-level converter are performed. It is shown that both M2C and HCMC provide lower conversion loss compare to the conventional two-level converter. A control strategy for these two multilevel converters in point-to-point and multi-terminal HVDC systems is also studied. Simulation results show that these two converters are able to operate over the entire specified P-Q capability curve and are capable of riding through ac faults without imposing any over-voltage or over-current on the converter switches.
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Cwikowski, Oliver. "Synthetic testing of high voltage direct current circuit breakers." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/synthetic-testing-of-high-voltage-direct-current-circuit-breakers(2f15e62f-8b2c-4e29-884e-323b90af2d11).html.
Повний текст джерелаАнотація:
The UK is facing two major challenges in the development of its electricity network. First, two thirds of the existing power stations are expected to close by 2030. Second, is the requirement to reduce its CO2 emissions by 80% by 2050. Both of these challenges are significant in their own right. The fact that they are occurring at the same time, generates a significant amount of threats to the existing power system, but also provides many new opportunities. In order to meet both these challenges, significant amounts of offshore wind generation has been installed in the UK. For the wind generation with the longest connections to land, Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) transmission has to be used. Due to the high power rating of the offshore wind farms, compared to the limited transmission capacity of the links, a large number of point-to-point connections are required. This has lead to the concept of HVDC grids being proposed, in order to reduce the amount of installed assets required. HVDC grids are a new transmission environment and the fundamental question of how they will protect themselves must be answered. Several new technologies are under consideration to provide this protection, one of which is the HVDC circuit breaker. As HVDC circuit breakers are a new technology, they must be tested in a laboratory environment to prove their operation and improve their Technology Readiness Level (TRL). This thesis is concerned with how such HVDC circuit breakers are operated, rated, and tested in a laboratory environment. A review of the existing circuit breaker technologies is given, along with descriptions of several novel circuit breakers developed in this thesis. A standardized method of rating DC circuit breaker and their associated test circuit is developed. Mathematical analysis of several circuit breakers is derived from first principles and low power prototypes are developed to validate these design concepts. A high power test circuit is then constructed and a semiconductor circuit breaker is tested. The key learning outcomes from this testing are provided.
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Singh, Akanksha. "A boost current source inverter based generator-converter topology for direct drive wind turbines." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/34676.
Повний текст джерелаАнотація:
Doctor of PhilosophyDepartment of Electrical and Computer Engineering
Behrooz Mirafzal
In this dissertation, a new topology for Direct-Drive Wind Turbines (DDWTs) with a new power electronics interface and a low-voltage generator design is presented. In the presented power electronics interface, the grid - side converter is replaced by a boost Current Source Inverter (CSI) which eliminates the required dc-bus capacitors resulting in an increase in the lifetime of DDWTs. The inherently required dc-link inductor for this topology is eliminated by utilizing the inductance of the Permanent Magnet Synchronous Generator (PMSG). The proposed three-phase boost CSI is equipped with Reverse-Blocking IGBTs (RB-IGBT) and the Phasor Pulse Width Modulation (PPWM) switching pattern to provide a 98% efficiency and high boost ratios ([superscript V]LL/V[subscript dc]) up to 3.5 in a single stage. In this dissertation, Phasor Pulse Width Modulation (PPWM) pattern for the boost – CSI is also modified and verified through simulation and experimental results. In order to realize potential capabilities of the boost inverter and to assist its penetration into renewable energy systems, the boost inverter dynamic behaviors are studied in this dissertation. Then, the developed models are verified using circuit simulations and experiments on a laboratory-scale boost – CSI equipped with RB-IGBTs. The developed dynamic models are used to study the stability of the boost – CSI through root locus of small signal poles (eigenvalues) as control inputs and load parameters vary within the boost inverter's operating limits. The dynamic models are also used to design the control schemes for the boost – CSI for both stand-alone and grid-tied modes of operation. The developed controllers of the boost – CSI are verified through simulation and experimental results. In this dissertation, the boost – CSI steady-state characterization equations are also developed and verified. The developed boost – CSI is used to replace the grid - side converter in a DDWT. A reliability analysis on the power electronics interface of an existing and developed topology is presented to demonstrate the increase in the mean time between failures. The boost – CSI enables conversion of a low dc voltage to a higher line-to-line voltage enabling the implementation of a low-voltage generator. This further enables a reduction in the number poles required in DDWT generators. The feasibility of the presented low-voltage generator is investigated through finite element computations. In this dissertation, a 1.5MW low-voltage generator designed for the proposed topology is compared with an existing 1.5MW permanent magnet synchronous generator for DDWTs to demonstrate the reduction in the volume, weight, and amount of permanent magnet materials required in the generator. The feasibility of the developed system is supported by a set of MATLAB/Simulink simulations and laboratory experiments on the closed-loop stand-alone and grid-tied systems.
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Ridenour, Daniel Keith. "Examination of Power Systems Solutions Considering High Voltage Direct Current Transmission." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/63927.
Повний текст джерелаАнотація:
Since the end of the Current Wars in the 19th Century, alternating current (AC) has dominated the production, transmission, and use of electrical energy. The chief reason for this dominance was (and continues to be) that AC offers a way minimize transmission losses yet transmit large power from generation to load. With the Digital Revolution and the entrance of most of the post-industrialized world into the Information Age, energy usage levels have increased due to the proliferation of electrical and electronic devices in nearly all sectors of life. A stable electrical grid has become synonymous with a stable nation-state and a healthy populace.
Large-scale blackouts around the world in the 20th and the early 21st Centuries highlighted the heavy reliance on power systems and because of that, governments and utilities have strived to improve reliability. Simultaneously occurring with the rise in energy usage is the mandate to cut the pollution by generation facilities and to mitigate the impact grid expansion has on environment as a whole. The traditional methods of transmission expansion are beginning to show their limits as utilities move generation facilities farther from load centers, which reduces geographic diversity, and the integration of nondispatchable, renewable energy sources upsets the current operating regime. A challenge faces engineers - how to expand generation, expand transmission capacity, and integrate renewable energy sources while maintaining maximum system efficiency and reliability.
A technology that may prove beneficial to the operation of power system is high voltage direct current transmission. The technology brings its own set of advantages and disadvantages, which are in many ways the complement of AC. It is important to update transmission planning processes to account for the new possibilities that HVDC offers. This thesis submits a discussion of high voltage direct current transmission technology itself and an examination of how HVDC can be considered in the planning process.Master of Science
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Chen, Yijing. "Nonlinear Control and Stability Analysis of Multi-Terminal High Voltage Direct Current Networks." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112041/document.
Повний текст джерелаАнотація:
Cette thèse a été consacrée à l'étude des réseaux multi-terminaux haute tension à courant continu (MTDC). Les principales contributions étaient dans le domaine du contrôle automatique non linéaire, appliquées aux systèmes électriques, électronique de puissance et les sources d'énergie renouvelables. Le travail de recherche a été lancé avec l'intention de combler certaines lacunes entre la théorie et la pratique, en particulier: 1) d'enquêter sur diverses approches de contrôle pour le but d'améliorer la performance des systèmes MTDC; 2) d'établir des connexions entre la conception du contrôle empiriques existantes et analyse théorique; 3) d'améliorer la compréhension du comportement multi-échelle de temps des systèmes MTDC caractérisés par la présence de transitoires lents et rapides en réponse aux perturbations externes. En conséquence, ce travail de thèse peut être mis en trois domaines, à savoir la conception non linéaire de commande de systèmes MTDC, analyse des comportements dynamiques de système MTDC et l'application de systèmes MTDC pour le contrôle de fréquence des systèmes de climatisationThis dissertation was devoted to the study of multi-terminal high voltage direct current (MTDC) networks. The main contributions were in the field of nonlinear automatic control, applied to power systems, power electronics and renewable energy sources. The research work was started with the intention of filling some gaps between the theory and the practice, in particular: 1) to investigate various control approaches for the purpose of improving the performance of MTDC systems; 2) to establish connections between existing empirical control design and theoretical analysis; 3) to improve the understanding of the multi-time-scale behavior of MTDC systems characterized by the presence of slow and fast transients in response to external disturbances. As a consequence, this thesis work can be put into three areas, namely nonlinear control design of MTDC systems, analysis of MTDC system's dynamic behaviors and application of MTDC systems for frequency control of AC systems
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Giraneza, Martial. "High voltage direct current (HVDC) in applications for distributed independent power providers (IPP)." Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/1077.
Повний текст джерелаАнотація:
Thesis submitted in fulfillment of the requirements for the degree
Master of Technology: Electrical Engineering
in the Faculty of Engineering
at the Cape Peninsula University of Technology
2013The development of power electronics did remove most of technical limitations that high voltage direct current (HVDC) used to have. HVDC, now, is mostly used for the transmission of bulk power over long distances and for the interconnection of asynchronous grid. Along with the development of the HVDC, the growth of power demand also increased beyond the utilities capacities. Besides the on-going increasing of power demand, the reforms in electricity market have led to the liberalization and the incorporation of Independent power providers in power system operation. Regulations and rules have been established by regulating authority for grid integration of Independent power providers. With the expected increase of penetration level of those new independent power providers, result of economic reason and actual green energy trend, best method of integration of those new power plants are required. In this research HVDC technology, namely VSC-HVDC is used as interface for connecting independent power providers units to the grid. VSC-HVDC has various advantages such as short-circuit contribution and independent control of active and reactive power. VSC-HVDC advantages are used for a safe integration of IPPs and make them participate to grid stabilization. MATLAB/Simulink simulations of different grid connected, through VSC-HVDC system, IPPs technologies models are performed. For each IPP technology model, system model performances are studied and dynamics responses during the disturbance are analyzed in MATLAB/ Simulink program. The simulation results show that the model satisfy the standard imposed by the regulating authority in terms of power quality and grid support. Also the results show the effect of the VSC-HVDC in preventing faults propagation from grid to integrated IPPs units.
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Krige, Ernst. "Harmonic interaction between weak AC systems and VSC-based HVDC schemes." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71704.
Повний текст джерелаАнотація:
Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: The implementation of the Caprivi Link Interconnector (CLI) High Voltage Direct Current (HVDC) scheme in 2010 connecting the weak Namibian and Zambian Alternating Current (AC) transmission networks via overhead line is based on Voltage Source Converter (VSC) technology. This world-first combination of attributes presents a unique opportunity to study harmonic interaction between weak AC systems and VSC-based HVDC schemes. Relatively few publications exist that focus on AC and DC harmonic interaction and very few refer to VSC HVDC schemes. Because weak AC systems are much more prone to harmonic distortion than strong AC systems, there is a clear motivation for more detailed work in this field. In order to understand the context wherein AC and DC harmonic interaction exists, the fields of AC power system harmonic analysis and resonance, VSC switching theory, HVDC scheme configurations, Pulse Width Modulation (PWM) techniques and frequency domain analysis techniques are discussed. This thesis then presents the concept of Harmonic Amplitude Transfer Ratio (HATR) by a theoretical analysis of AC and DC harmonic interaction due to the fundamental component, as well as harmonic interaction due to scheme characteristic harmonics and is compared to the simulation results obtained from different software solutions. Simulation and modelling techniques for AC and DC harmonic interaction are discussed including AC and DC systems modelling. The theoretical results and simulation results are compared to the results obtained from a real life case study on the CLI HVDC scheme where a harmonic resonance condition occurred. The correlation of these three sets of results confirms the validity of the theories presented and possible mitigation of the case study resonance problems is explored. The results and conclusion highlight a variety of interesting points on harmonic sequence components analysis, VSC zero sequence elimination, AC and DC harmonic interaction due to the fundamental component and the HATR for different PWM methods, AC and DC harmonic interaction due to scheme characteristic harmonics, modelling techniques and mitigation for the resonance conditions experienced in the analysed real life case study.
AFRIKAANSE OPSOMMING: Die implementering van die Caprivi Skakel Tussenverbinder (CLI) hoogspannings- gelykstroom (HSGS) skema in 2010 wat die swak Namibiese and Zambiese Wisselstroom (WS) transmissienetwerke verbind via „n oorhoofse lyn is gebasseer op Spanningsgevoerde-omsetter tegnologie. Hierdie wêreld-eerste kombinasie van eienskappe verskaf „n unieke geleentheid om harmoniese interaksie tussen swak WS stelsels en Spanningsgevoerde-omsetter Hoogspannings GS stelsels te bestudeer. Relatief min publikasies wat fokus op WS en GS harmoniese interaksie bestaan, en baie min verwys na Spanningsgevoerde-omsetter Hoogspannings GS skemas. Omdat swak WS stelsels baie meer geneig is tot harmoniese verwringing as sterk WS stelsels, is daar „n duidelike motivering vir meer gedetaileerde werk in hierdie veld. Om die konteks te verstaan waarin WS en GS harmoniese interaksie bestaan, word die velde van WS kragstelsel harmoniese analise en resonansie, Spanningsgevoerde-omsetter skakelteorie, Hoogspannings GS skema opstellings, Pulswydte Modulasie (PWM) tegnieke, en frekwensiegebied analiese tegnieke bespreek. Hierdie tesis stel dan die konsep van Harmoniese Amplitude Oordragsverhouding voor deur „n teoretiese analise van WS en GS harmoniese interaksie na aanleiding van die fundamentele komponent, asook harmoniese interaksie a.g.v. harmonieke wat die stelsel kenmerk en word vergelyk met die simulasieresultate verkry uit verskilllende sagteware oplossings. Simulasie- en modelleringstegnieke vir WS en GS harmoniese interaksie word bespreek insluitend WS- en GS stelselmodellering. Die teoretiese resultate en simulasieresultate word vergelyk met die resultate wat verkry is uit „n werklike gevallestudie op die CLI HSGS skema waar „n harmoniese resonansie toestand voorgekom het. Die ooreenkomste tussen hierdie drie stelle resultate bevestig die geldigheid van die teorieë soos uiteengeset voor, en die moontlike verbetering van die gevallestudie resonansie probleme word verken. Die resultate en samevatting beklemtoon „n verskeidenheid punte aangaande harmoniese volgorde-komponent analiese, Spanningsgevoerde-omsetter zero-volgorde uitskakeling, WS en GS harmoniese interaksie na aanleiding van die fundamentele komponent en die Harmoniese Amplitude Oordragsverhouding vir verskillende PWM metodes, WS en GS harmoniese interaksie na aanleiding van skema-kenmerkende harmonieke, modelleringstegnieke, asook verbetering van die resonansie toestande soos ervaar in die analise van die werklike gevallestudie.
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Čedo, Žlebič. "Uticaj jednosmerne struje na karakteristike podešljivih feritnih komponenti." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2019. https://www.cris.uns.ac.rs/record.jsf?recordId=110180&source=NDLTD&language=en.
Повний текст джерелаАнотація:
U okviru doktorske disertacije, realizovane su podešljive feritne komponente sa jezgrima koja su proizvedena od komercijalno dostupnih ESL 40011 feritnih traka čije se induktivnosti podešavaju primenom jednosmerne struje. Rad realizovanih podešljivih feritnih komponenti je verifikovan u kolu DC-DC konvertora podizača napona. U disertaciji je predložena merna metoda koja omogućava ispitivanje uticaja jednosmerne struje na karakteristike SMD induktora postavljenih u realnom okruženju. Metoda je verifikovana na komercijalno dostupnim SMD induktorima.As part of this thesis variable ferite components with cores produced from comercialy available ESL 40011 ferite tapes manufactured in Low Temperature Co-fired Ceramic technology are implemented. Inductivity of the components is varied by applying DC current. Functionality of the implemented ferite components is verified in a circuit of DC-DC boost converter. This thesis proposes a measurement method which enables examining the influence of DC current on the characteristics of SMD inductors in real environment. The method is verified on comercialy available SMD inductors
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Hadjikypris, Melios. "Supervisory control scheme for FACTS and HVDC based damping of inter-area power oscillations in hybrid AC-DC power systems." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/supervisory-control-scheme-for-facts-and-hvdc-based-damping-of-interarea-power-oscillations-in-hybrid-acdc-power-systems(cc03b44a-97f9-44ec-839f-5dcbcf2801f1).html.
Повний текст джерелаАнотація:
Modern interconnected power systems are becoming highly complex and sophisticated, while increasing energy penetrations through congested inter-tie lines causing the operating point approaching stability margins. This as a result, exposes the overall system to potential low frequency power oscillation phenomena following disturbances. This in turn can lead to cascading events and blackouts. Recent approaches to counteract this phenomenon are based on utilization of wide area monitoring systems (WAMS) and power electronics based devices, such as flexible AC transmission systems (FACTS) and HVDC links for advanced power oscillation damping provision. The rise of hybrid AC-DC power systems is therefore sought as a viable solution in overcoming this challenge and securing wide-area stability. If multiple FACTS devices and HVDC links are integrated in a scheme with no supervising control actions considered amongst them, the overall system response might not be optimal. Each device might attempt to individually damp power oscillations ignoring the control status of the rest. This introduces an increasing chance of destabilizing interactions taking place between them, leading to under-utilized performance, increased costs and system wide-area stability deterioration. This research investigates the development of a novel supervisory control scheme that optimally coordinates a parallel operation of multiple FACTS devices and an HVDC link distributed across a power system. The control system is based on Linear Quadratic Gaussian (LQG) modern optimal control theory. The proposed new control scheme provides coordinating control signals to WAMS based FACTS devices and HVDC link, to optimally and coherently counteract inter-area modes of low frequency power oscillations inherent in the system. The thesis makes a thorough review of the existing and well-established improved stability practises a power system benefits from through the implementation of a single FACTS device or HVDC link, and compares the case –and hence raises the issue–when all active components are integrated simultaneously and uncoordinatedly. System identification approaches are also in the core of this research, serving as means of reaching a linear state space model representative of the non-linear power system, which is a pre-requisite for LQG control design methodology.
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Sastry, Jyoti. "Direct AC control of grid assets." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41109.
Повний текст джерелаАнотація:
The objective of the proposed research is to investigate feasible approaches to dynamic control of the power grid. Growth in the demand for electric power, and an increase in the penetration of renewable energy resources are causing congestion on an already aging power grid. Conventional grid control involves the use of static assets that operate on long time scales. These assets provide no dynamic control on the grid, and are typically used for scheduled support. Existing solutions (FACTS devices) to dynamic grid control have seen minimal market penetration because of high cost and low reliability. The proposed research provides a solution for dynamic control of the power grid that augments existing grid assets with a thin AC converter (TACC) to realize enhanced dynamic control. The TACC is a direct AC converter with filter elements and no bulk energy storage that dynamically reflects the asset value on the grid. The converter has a fail-normal mode of operation that returns the asset to its initial operating state, thereby not degrading system reliability. Some applications of TACCs include Inverter-Less STATCOMs and Controllable Network Transformers, which are realized by augmenting shunt VAR capacitors and load tap changers respectively. The principle of virtual quadrature sources is proposed to enable conditioning of AC voltages and currents. The concept is a novel method to realize control of phase angle and, or harmonics in single-phase AC converters, with no bulk energy storage. This concept is used to control the TACC and provides the asset with significantly enhanced control capabilities. Scaling of the TACC to utility voltage and power levels has been addressed by proposing a novel multilevel direct AC converter. The concept proposes the use of commercially available low cost semiconductor devices to realize high power converters. The specific application chosen to validate the concept of TACCs, through a medium voltage design, is the Inverter-less STATCOM.
Книги з теми "Direct current source"
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NTT, Fashiritīzu Kabushiki Kaisha. Jiritsu, bunsangata enerugī shakai no jitsugen ni muketa chokuryū hōshiki ni yoru chiikikan sōgo enerugī yūzū shisutemu no kaihatsu seika hōkokusho. [Tōkyō-to Minato-ku]: NTT Fashiritīzu, 2013.
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Kaisha, NTT Fashiritīzu Kabushiki. Jiritsu, bunsangata enerugī shakai no jitsugen ni muketa chokuryū hōshiki ni yoru chiikikan sōgo enerugī yūzū shisutemu no kaihatsu: Seika hōkokusho. [Tōkyō-to Minato-ku]: NTT Fashiritīzu, 2014.
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Nash, Howard. Foreign direct investment in the United States: An annotated guide to current data sources. Monticello, Ill., USA: Vance Bibliographies, 1987.
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Nash, Howard. Foreign direct investment in the United States: An annotated guide to current data sources. Monticello, Ill., USA: Vance Bibliographies, 1987.
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Weerdt, Hilde, and Franz-Julius Morche, eds. Political Communication in Chinese and European History, 800-1600. NL Amsterdam: Amsterdam University Press, 2021. http://dx.doi.org/10.5117/9789463720038.
Повний текст джерелаАнотація:
Based on a collaboration between historians of Chinese and European politics, Political Communication in Chinese and European History, 800-1600 offers a first comprehensive overview of current research on political communication in middle-period European and Chinese history. The chapters present new work on the sources and processes of political communication in European and Chinese history partly through juxtaposing and combining formerly separate historiographies and partly through direct comparison. Contrary to earlier comparative work on empires and state formation, which aimed to explain similarities and differences with encompassing models and new theories of divergence, the goal is to further conversations between historians by engaging regional historiographies from the bottom up.
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van Kooten, G. Cornelis, and Linda Voss, eds. International trade in forest products: lumber trade disputes, models and examples. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789248234.0000.
Повний текст джерелаАнотація:
Abstract Because of the long-standing Canada-United States lumber trade dispute and the current pressure on the world's forests as a renewable energy source, much attention has been directed toward the modelling of international trade in wood products. Two types of trade models are described in this book: one is rooted in economic theory and mathematical programming, and the other consists of two econometric/statistical models--a gravity model rooted in theory and an approach known as GVAR that relies on time series analyses. The purpose of the book is to provide the background theory behind models and enable readers to easily construct their own models to analyze policy questions, whether in forestry or another sector. Examples in the book illustrate how models can be used to say something about a variety of issues, including identification of the gains and losses to various players in the North American softwood lumber business, and the potential for redirecting sales of lumber to countries outside the United States. The discussion is expanded to include other products besides lumber, and used to examine, for example, the effects of log export restrictions by one naton on all other forestry jurisdictions, the impacts of climate policies as they relate to the global forest sector, and the impact of oil prices on forest product markets throughout the world.
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S, Daniels Taumi, and United States. National Aeronautics and Space Administration. Scientific and Technical Information Division., eds. A linearly controlled direct-current power source for high-current inductive loads in a magnetic suspension wind tunnel. [Washington, D.C.]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Division, 1990.
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Shields, James Phillip. Design, construction, and characterization of a six-electrode, direct current, variable length plasma source for atomic emmission spectroscopy. 1987.
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Eissa, M. M. Medium Voltage Direct Current Grid: Resilient Operation, Control and Protection. Elsevier Science & Technology, 2019.
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Fisher, Maryanne L., ed. The Oxford Handbook of Women and Competition. Oxford University Press, 2014. http://dx.doi.org/10.1093/oxfordhb/9780199376377.001.0001.
Повний текст джерелаАнотація:
The topic of women’s competition has gained significant recent momentum. This book provides direct evidence of this growth and is the first scholarly volume to focus specifically on the topic. In general, the included chapters provide a definitive view of the current state of knowledge regarding women’s competition. Many of the chapters are theoretically grounded in an evolutionary framework, such that the authors investigate the adaptive nature of women’s competitive behavior, motivations, and cognitions. Other chapters rely on a different framework, with these authors instead arguing that sociocultural sources shape women's competition. In addition, while the book is primarily about women, some contributors focus their chapters on issues faced by adolescent girls, or mention developmental trajectories for young girls through to adulthood. Some authors focus on nonhuman females to provide a stronger background for understanding women. It is hoped that the information within this volume will serve as a source of inspiration to help guide future directions for research.
Частини книг з теми "Direct current source"
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Babouche, Randa, Nourelddine Henini, Kamel Saoudi, and Taki Eddine Ameur. "Sliding Mode Control of Voltage Source Converter Based High Voltage Direct Current System." In Advances in Green Energies and Materials Technology, 209–14. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0378-5_28.
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Teixeira-Neto, N. C., R. T. Azevedo-Cavalcanti, M. G. N. Monte-da-Silva, and A. E. F. Da-Gama. "Development of a Low-Cost, Open-Source Transcranial Direct-Current Stimulation Device (tDCS) for Clinical Trials." In XXVII Brazilian Congress on Biomedical Engineering, 827–33. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-70601-2_125.
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Kado, H., S. Kashiwaya, M. Higuchi, and H. Miura. "Direct Approach to an Inverse Problem: A Trial to Describe Signal Sources by Current Elements Distribution." In Advances in Biomagnetism, 579–82. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4613-0581-1_127.
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Garwood, Kim. "Supporting Academic Integrity in the Writing Centre: Perspectives of Student Consultants." In Academic Integrity in Canada, 431–47. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-83255-1_22.
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AbstractWriting centres are often described as safe spaces where students can explore their ideas and concerns, including questions about how to use and cite sources without plagiarizing. In many Canadian writing centres, these issues are addressed by student consultants who provide effective and influential peer-to-peer support in individual consultations. Little research, however, has directly examined the perspectives of student consultants in providing academic integrity support. This chapter provides a synthesis of what literature currently exists on the role of student consultants in supporting academic integrity before describing a case study with student writing consultants at the University of Guelph. Using data gathered through a survey, this chapter examines the experience and perceptions of student consultants in providing academic integrity support. The findings suggest that academic integrity conversations often arise indirectly, through conversations about referencing or paraphrasing. Student writing consultants consistently position themselves as intermediaries, helping protect students from academic misconduct by using a range of directive and non-directive strategies.
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Spencer, Ruth Viola. "Improvement of Human and Environmental Health Through Waste Management in Antigua and Barbuda." In Fostering Transformative Change for Sustainability in the Context of Socio-Ecological Production Landscapes and Seascapes (SEPLS), 215–28. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-6761-6_12.
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AbstractAntigua and Barbuda is currently experiencing an expansion in integrated waste management driven by local community groups. These events are catalytic and transformational, fit well into SEPLS methodologies, and contribute to many of the biodiversity targets and Sustainable Development Goals (SDGs). With waste being a direct driver of and major challenge for biodiversity, climate change and land degradation, many positive multi-dimensional impacts are being seen, realised and manifested that contribute positively to reducing land-based sources of pollution through community stewardship. Such local actions positively impact the sustainable management of natural resources and the protection of habitats. Likewise, they support land degradation neutrality, protection and safeguarding of the ecosystems that provide our soil, air and water resources, sustain livelihoods, and facilitate transfer of knowledge to children and youth.This attempt to pilot a circular economy approach is providing vocational and life skills training, as well as income generation for the local community, including new forms of capacity building and development, while reducing soil, water and air pollution. Public-private partnerships built through this project are motivating other groups to follow a similar path to biodiversity transformation. Changes in attitudes and behaviours, and the building of knowledge and capacities in the next generation, is taking place through school and community outreach programmes.The project has led to community empowerment in understanding that everyone has a role to play in sustainable development and that through collective actions, changes to improve public health can be made.
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"On-Site Emergency Direct Current Source." In Electrical Systems for Nuclear Power Plants, 101–14. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2018. http://dx.doi.org/10.1002/9781119483687.ch7.
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"DC Grids with Voltage Source Converters and Power-Flow Model." In High-Voltage Direct-Current Transmission, 316–23. Chichester, UK: John Wiley & Sons, Ltd, 2015. http://dx.doi.org/10.1002/9781118846704.ch24.
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Hai-Jew, Shalin. "Action Potentials." In Open Source Technology, 812–69. IGI Global, 2015. http://dx.doi.org/10.4018/978-1-4666-7230-7.ch039.
Повний текст джерелаАнотація:
An ideology is defined as a set of ideas that “explains and evaluates social conditions, helps people understand their place in society, and provides a program for social and political action” (Ball & Dagger, 2011, p. 4). As such, these concepts underpin the actions of various groups and organizations, including that of the Anonymous hacker group, which professes no ideology or creed. Rather, the group has styled itself as a kind of anarchic global brain connected by various spaces on the Internet. This work explores four main data streams to extrapolate the group's ideology: the current socio-political context of hacking and hacktivism; the group's self-definition (through its professed values); the group's actions (through the “propaganda of the deed”); and the insights of others about the group This chapter defines the socio-technical context of this Anonymous hacker socio-political movement, which draws ideas from the Hacker Manifesto 2.0, which suggests the advent of a new economic system with the new technological vectors (mediums of communication). This movement is apparently pushing forth the advent of a new information regime in which the abstraction of ideas adds a “surplus” economic value that may be tapped. Styled as fighters against government tyranny, they are pushing hard against an international regime of intellectual property and information control by governments and corporations. This is being published in the spirit that (some) information wants to be free and that there is a value in direct discourse.
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Korzyk, Sr. "Integrating Cooperative Engagement Capability into Network-Centric Information System Security." In Current Security Management & Ethical Issues of Information Technology, 50–62. IGI Global, 2003. http://dx.doi.org/10.4018/978-1-93177-743-8.ch003.
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The U.S. military’s concept of a Cooperative Engagement Capability should serve as a useful referent for those attempting to design/develop large scale, organization-wide information security systems. This concept involves centralizing command over the entire suite of defensive assets (naval, air, ground) available in some region or locale; whenever a threat is directed against any US force element (a ship, an infantry unit, etc.), this central authority would then be expected to direct the deployment of whatever appears to be the most efficient countermeasure…in light of prospective as well as actual threats. This is a dramatic departure from the traditional decentralized approach, whereby each force element was expected to draw on its own defensive measures to counter any threat directed at it from any source. Industrial/commercial organizations might draw on the logic of the Cooperative Engagement Capability logic in devising a system to secure its informational assets.
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I. Abu-Eishah, Samir, Manal D.M. Raheem, Fatma A.S. Aljasmi, Fatima M.O. Alameri, Amna G.R. Alblooshi, and Intesar F.R. Alnahdi. "A Zero-Waste Process for the Treatment of Spent Potliner (SPL) Waste." In Current Topics in Recycling [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99055.
Повний текст джерелаАнотація:
This work presents a deep analyses of an environmentally friendly process to recover all valuable minerals contained in the spent potliner (SPL) such as graphite carbon and aluminum fluoride (AlF3) and production of sodium sulfate (Na2SO4) and gypsum (CaSO4) when H2SO4 is used as the leaching agent. The level of emission of hazardous gases such as HCN (weak acid) and HF are minimized by direct scrubbing of the HCN in aqueous AgNO3 solution to produce a stable silver cyanide (AgCN) product. The HF can be recovered as a liquid by condensation and used within the process and/or in production of metal fluorides such as the highly-soluble potassium fluoride (KF); a main source of fluoride in industry. Almost pure CO2 gas is also recovered from the process gas streams.
Тези доповідей конференцій з теми "Direct current source"
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Lu, Dapeng, Xiongfei Wang, and Frede Blaabjerg. "Stability analysis of direct current control in current source rectifier." In 2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia (IFEEC 2017 - ECCE Asia). IEEE, 2017. http://dx.doi.org/10.1109/ifeec.2017.7992045.
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Hu, Anping, David Xu, Jianhui Su, and Bin Wu. "DC-link current balancing and ripple reduction for direct parallel current-source converters." In IECON 2012 - 38th Annual Conference of IEEE Industrial Electronics. IEEE, 2012. http://dx.doi.org/10.1109/iecon.2012.6388987.
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Ayad, Ayman, Petros Karamanakos, and Ralph Kennel. "Direct model predictive current control of quasi-Z-source inverters." In 2015 IEEE International Symposium on Predictive Control of Electrical Drives and Power Electronics (PRECEDE). IEEE, 2015. http://dx.doi.org/10.1109/precede.2015.7395585.
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Belchenko, Yu. "Study of Direct Current Negative Ion Source for Medicine Accelerator." In PRODUCTION AND NEUTRALIZATION OF NEGATIVE IONS AND BEAMS: 10th International Symposium on Production and Neutralization of Negative Ions and Beams. AIP, 2005. http://dx.doi.org/10.1063/1.1908309.
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Alsokhiry, Fahad, Yusuf Al-Turki, Ibrahim Abdelsalam, and Grain Philip Adam. "Modular Two-Level Voltage Source Converter for Direct Current Transmission Systems." In 2018 5th International Symposium on Environment-Friendly Energies and Applications (EFEA). IEEE, 2018. http://dx.doi.org/10.1109/efea.2018.8617108.
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Sato, Akira, and Toshihiko Noguchi. "Multi-Level Current-Source PWM Rectifier Based on Direct Power Control." In IECON 2007 - 33rd Annual Conference of the IEEE Industrial Electronics Society. IEEE, 2007. http://dx.doi.org/10.1109/iecon.2007.4460134.
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Zheng, Xiaodong, Nengling Tai, Zhongyu Wu, and James Thorp. "Harmonic current protection scheme for voltage source converter-based high-voltage direct current transmission system." In 2015 IEEE Power & Energy Society General Meeting. IEEE, 2015. http://dx.doi.org/10.1109/pesgm.2015.7285723.
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Baktash, Amir, and Abolfazl Vahedi. "Sensorless direct power control of current source rectifier based on virtual flux." In Automation (MED 2008). IEEE, 2008. http://dx.doi.org/10.1109/med.2008.4602128.
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Ginarsa, I. Made, Agung Budi Muljono, and I. Made Ari Nrartha. "Simulation of ANFIS Controller to Line Commutation Based on Current Source Converter High Voltage Direct Current System." In 2019 IEEE Conference on Energy Conversion (CENCON). IEEE, 2019. http://dx.doi.org/10.1109/cencon47160.2019.8974701.
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Wang, Xu, Kaizheng Huang, Shijie Yan, and Bin Xu. "Simulation of Three-Phase Voltage Source PWM Rectifier Based on Direct Current Control." In 2008 Congress on Image and Signal Processing. IEEE, 2008. http://dx.doi.org/10.1109/cisp.2008.705.
Повний текст джерелаЗвіти організацій з теми "Direct current source"
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Wolf, Shmuel, and William J. Lucas. Involvement of the TMV-MP in the Control of Carbon Metabolism and Partitioning in Transgenic Plants. United States Department of Agriculture, October 1999. http://dx.doi.org/10.32747/1999.7570560.bard.
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The function of the 30-kilodalton movement protein (MP) of tobacco mosaic virus (TMV) is to facilitate cell-to-cell movement of viral progeny in infected plants. Our earlier findings have indicated that this protein has a direct effect on plasmodesmal function. In addition, these studies demonstrated that constitutive expression of the TMV MP gene (under the control of the CaMV 35S promoter) in transgenic tobacco plants significantly affects carbon metabolism in source leaves and alters the biomass distribution between the various plant organs. The long-term goal of the proposed research was to better understand the factors controlling carbon translocation in plants. The specific objectives were: A) To introduce into tobacco and potato plants a virally-encoded (TMV-MP) gene that affects plasmodesmal functioning and photosynthate partitioning under tissue-specific promoters. B) To introduce into tobacco and potato plants the TMV-MP gene under the control of promoters which are tightly repressed by the Tn10-encoded Tet repressor, to enable the expression of the protein by external application of tetracycline. C) To explore the mechanism by which the TMV-MP interacts with the endogenous control o~ carbon allocation. Data obtained in our previous project together with the results of this current study established that the TMV-MP has pleiotropic effects when expressed in transgenic tobacco plants. In addition to its ability to increase the plasmodesmal size exclusion limit, it alters carbohydrate metabolism in source leaves and dry matter partitioning between the various plant organs, Expression of the TMV-MP in various tissues of transgenic potato plants indicated that sugars and starch levels in source leaves are reduced below those of control plants when the TMV-MP is expressed in green tissue only. However, when the TMV-MP was expressed predominantly in PP and CC, sugar and starch levels were raised above those of control plants. Perhaps the most significant result obtained from experiments performed on transgenic potato plants was the discovery that the influence of the TMV-MP on carbohydrate allocation within source leaves was under developmental control and was exerted only during tuber development. The complexity of the mode by which the TMV-MP exerts its effect on the process of carbohydrate allocation was further demonstrated when transgenic tobacco plants were subjected to environmental stresses such as drought stress and nutrients deficiencies, Collectively, these studies indicated that the influence of the TMV-MP on carbon allocation L the result of protein-protein interaction within the source tissue. Based on these results, together with the findings that plasmodesmata potentiate the cell-to-cell trafficking of viral and endogenous proteins and nucleoproteins complexes, we developed the theme that at the whole plant level, the phloem serves as an information superhighway. Such a long-distance communication system may utilize a new class of signaling molecules (proteins and/or RNA) to co-ordinate photosynthesis and carbon/nitrogen metabolism in source leaves with the complex growth requirements of the plant under the prevailing environmental conditions. The discovery that expression of viral MP in plants can induce precise changes in carbon metabolism and photoassimilate allocation, now provide a conceptual foundation for future studies aimed at elucidating the communication network responsible for integrating photosynthetic productivity with resource allocation at the whole-plant level. Such information will surely provide an understanding of how plants coordinate the essential physiological functions performed by distantly-separated organs. Identification of the proteins involved in mediating and controlling cell-to-cell transport, especially at the companion cell-sieve element boundary, will provide an important first step towards achieving this goal.
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Kiv, Arnold E., Vladyslav V. Bilous, Dmytro M. Bodnenko, Dmytro V. Horbatovskyi, Oksana S. Lytvyn, and Volodymyr V. Proshkin. The development and use of mobile app AR Physics in physics teaching at the university. [б. в.], July 2021. http://dx.doi.org/10.31812/123456789/4629.
Повний текст джерелаАнотація:
This paper outlines the importance of using Augmented Reality (AR) in physics education at the university as a valuable tool for visualization and increasing the attention and motivation of students to study, solving educational problems related to future professional activities, improving the interaction of teachers and students. Provided an analysis of the types of AR technology and software for developing AR apps. The sequences of actions for developing the mobile application AR Physics in the study of topics: “Direct electronic current”, “Fundamentals of the theory of electronic circuits”. The software tools for mobile application development (Android Studio, SDK, NDK, Google Sceneform, 3Ds MAX, Core Animation, Asset Media Recorder, Ashampoo Music Studio, Google Translate Plugin) are described. The bank of 3D models of elements of electrical circuits (sources of current, consumers, measuring devices, conductors) is created. Because of the students’ and teachers’ surveys, the advantages and disadvantages of using AR in the teaching process are discussed. Mann-Whitney U-test proved the effectiveness of the use of AR for laboratory works in physics by students majoring in “Mathematics”, “Computer Science”, and “Cybersecurity”.
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Shani, Uri, Lynn Dudley, Alon Ben-Gal, Menachem Moshelion, and Yajun Wu. Root Conductance, Root-soil Interface Water Potential, Water and Ion Channel Function, and Tissue Expression Profile as Affected by Environmental Conditions. United States Department of Agriculture, October 2007. http://dx.doi.org/10.32747/2007.7592119.bard.
Повний текст джерелаАнотація:
Constraints on water resources and the environment necessitate more efficient use of water. The key to efficient management is an understanding of the physical and physiological processes occurring in the soil-root hydraulic continuum.While both soil and plant leaf water potentials are well understood, modeled and measured, the root-soil interface where actual uptake processes occur has not been sufficiently studied. The water potential at the root-soil interface (yᵣₒₒₜ), determined by environmental conditions and by soil and plant hydraulic properties, serves as a boundary value in soil and plant uptake equations. In this work, we propose to 1) refine and implement a method for measuring yᵣₒₒₜ; 2) measure yᵣₒₒₜ, water uptake and root hydraulic conductivity for wild type tomato and Arabidopsis under varied q, K⁺, Na⁺ and Cl⁻ levels in the root zone; 3) verify the role of MIPs and ion channels response to q, K⁺ and Na⁺ levels in Arabidopsis and tomato; 4) study the relationships between yᵣₒₒₜ and root hydraulic conductivity for various crops representing important botanical and agricultural species, under conditions of varying soil types, water contents and salinity; and 5) integrate the above to water uptake term(s) to be implemented in models. We have made significant progress toward establishing the efficacy of the emittensiometer and on the molecular biology studies. We have added an additional method for measuring ψᵣₒₒₜ. High-frequency water application through the water source while the plant emerges and becomes established encourages roots to develop towards and into the water source itself. The yᵣₒₒₜ and yₛₒᵢₗ values reflected wetting and drying processes in the rhizosphere and in the bulk soil. Thus, yᵣₒₒₜ can be manipulated by changing irrigation level and frequency. An important and surprising finding resulting from the current research is the obtained yᵣₒₒₜ value. The yᵣₒₒₜ measured using the three different methods: emittensiometer, micro-tensiometer and MRI imaging in both sunflower, tomato and corn plants fell in the same range and were higher by one to three orders of magnitude from the values of -600 to -15,000 cm suggested in the literature. We have added additional information on the regulation of aquaporins and transporters at the transcript and protein levels, particularly under stress. Our preliminary results show that overexpression of one aquaporin gene in tomato dramatically increases its transpiration level (unpublished results). Based on this information, we started screening mutants for other aquaporin genes. During the feasibility testing year, we identified homozygous mutants for eight aquaporin genes, including six mutants for five of the PIP2 genes. Including the homozygous mutants directly available at the ABRC seed stock center, we now have mutants for 11 of the 19 aquaporin genes of interest. Currently, we are screening mutants for other aquaporin genes and ion transporter genes. Understanding plant water uptake under stress is essential for the further advancement of molecular plant stress tolerance work as well as for efficient use of water in agriculture. Virtually all of Israel’s agriculture and about 40% of US agriculture is made possible by irrigation. Both countries face increasing risk of water shortages as urban requirements grow. Both countries will have to find methods of protecting the soil resource while conserving water resources—goals that appear to be in direct conflict. The climate-plant-soil-water system is nonlinear with many feedback mechanisms. Conceptual plant uptake and growth models and mechanism-based computer-simulation models will be valuable tools in developing irrigation regimes and methods that maximize the efficiency of agricultural water. This proposal will contribute to the development of these models by providing critical information on water extraction by the plant that will result in improved predictions of both water requirements and crop yields. Plant water use and plant response to environmental conditions cannot possibly be understood by using the tools and language of a single scientific discipline. This proposal links the disciplines of soil physics and soil physical chemistry with plant physiology and molecular biology in order to correctly treat and understand the soil-plant interface in terms of integrated comprehension. Results from the project will contribute to a mechanistic understanding of the SPAC and will inspire continued multidisciplinary research.
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Fluhr, Robert, and Volker Brendel. Harnessing the genetic diversity engendered by alternative gene splicing. United States Department of Agriculture, December 2005. http://dx.doi.org/10.32747/2005.7696517.bard.
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Our original objectives were to assess the unexplored dimension of alternative splicing as a source of genetic variation. In particular, we sought to initially establish an alternative splicing database for Arabidopsis, the only plant for which a near-complete genome has been assembled. Our goal was to then use the database, in part, to advance plant gene prediction programs that are currently a limiting factor in annotating genomic sequence data and thus will facilitate the exploitation of the ever increasing quantity of raw genomic data accumulating for plants. Additionally, the database was to be used to generate probes for establishing high-throughput alternative transcriptome analysis in the form of a splicing-specific oligonucleotide microarray. We achieved the first goal and established a database and web site termed Alternative Splicing In Plants (ASIP, http://www.plantgdb.org/ASIP/). We also thoroughly reviewed the extent of alternative splicing in plants (Arabidopsis and rice) and proposed mechanisms for transcript processing. We noted that the repertoire of plant alternative splicing differs from that encountered in animals. For example, intron retention turned out to be the major type. This surprising development was proven by direct RNA isolation techniques. We further analyzed EST databases available from many plants and developed a process to assess their alternative splicing rate. Our results show that the lager genome-sized plant species have enhanced rates of alternative splicing. We did advance gene prediction accuracy in plants by incorporating scoring for non-canonical introns. Our data and programs are now being used in the continuing annotation of plant genomes of agronomic importance, including corn, soybean, and tomato. Based on the gene annotation data developed in the early part of the project, it turned out that specific probes for different exons could not be scaled up to a large array because no uniform hybridization conditions could be found. Therefore, we modified our original objective to design and produce an oligonucleotide microarray for probing alternative splicing and realized that it may be reasonable to investigate the extent of alternative splicing using novel commercial whole genome arrays. This possibility was directly examined by establishing algorithms for the analysis of such arrays. The predictive value of the algorithms was then shown by isolation and verification of alternative splicing predictions from the published whole genome array databases. The BARD-funded work provides a significant advance in understanding the extent and possible roles of alternative splicing in plants as well as a foundation for advances in computational gene prediction.
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Lehotay, Steven J., and Aviv Amirav. Fast, practical, and effective approach for the analysis of hazardous chemicals in the food supply. United States Department of Agriculture, April 2007. http://dx.doi.org/10.32747/2007.7695587.bard.
Повний текст джерелаАнотація:
Background to the topic: For food safety and security reasons, hundreds of pesticides, veterinary drugs, and environmental pollutants should be monitored in the food supply, but current methods are too time-consuming, laborious, and expensive. As a result, only a tiny fraction of the food is tested for a limited number of contaminants. Original proposal objectives: Our main original goal was to develop fast, practical, and effective new approaches for the analysis of hazardous chemicals in the food supply. We proposed to extend the QuEChERS approach to more pesticides, veterinary drugs and pollutants, further develop GC-MS and LC-MS with SMB and combine QuEChERS with GC-SMB-MS and LC-SMB-EI-MS to provide the “ultimate” approach for the analysis of hazardous chemicals in food. Major conclusions, solutions and achievements: The original QuEChERS method was validated for more than 200 pesticide residues in a variety of food crops. For the few basic pesticides for which the method gave lower recoveries, an extensive solvent suitability study was conducted, and a buffering modification was made to improve results for difficult analytes. Furthermore, evaluation of the QuEChERS approach for fatty matrices, including olives and its oil, was performed. The QuEChERS concept was also extended to acrylamide analysis in foods. Other advanced techniques to improve speed, ease, and effectiveness of chemical residue analysis were also successfully developed and/or evaluated, which include: a simple and inexpensive solvent-in-silicone-tube extraction approach for highly sensitive detection of nonpolar pesticides in GC; ruggedness testing of low-pressure GC-MS for 3-fold faster separations; optimization and extensive evaluation of analyte protectants in GC-MS; and use of prototypical commercial automated direct sample introduction devices for GC-MS. GC-MS with SMB was further developed and combined with the Varian 1200 GCMS/ MS system, resulting in a new type of GC-MS with advanced capabilities. Careful attention was given to the subject of GC-MS sensitivity and its LOD for difficult to analyze samples such as thermally labile pesticides or those with weak or no molecular ions, and record low LOD were demonstrated and discussed. The new approach of electron ionization LC-MS with SMB was developed, its key components of sample vaporization nozzle and flythrough ion source were improved and was evaluated with a range of samples, including carbamate pesticides. A new method and software based on IAA were developed and tested on a range of pesticides in agricultural matrices. This IAA method and software in combination with GC-MS and SMB provide extremely high confidence in sample identification. A new type of comprehensive GCxGC (based on flow modulation) was uniquely combined with GC-MS with SMB, and we demonstrated improved pesticide separation and identification in complex agricultural matrices using this novel approach. An improved device for aroma sample collection and introduction (SnifProbe) was further developed and favorably compared with SPME for coffee aroma sampling. Implications, both scientific and agricultural: We succeeded in achieving significant improvements in the analysis of hazardous chemicals in the food supply, from easy sample preparation approaches, through sample analysis by advanced new types of GC-MS and LCMS techniques, all the way to improved data analysis by lowering LOD and providing greater confidence in chemical identification. As a result, the combination of the QuEChERS approach, new and superior instrumentation, and the novel monitoring methods that were developed will enable vastly reduced time and cost of analysis, increased analytical scope, and a higher monitoring rate. This provides better enforcement, an added impetus for farmers to use good agricultural practices, improved food safety and security, increased trade, and greater consumer confidence in the food supply.
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Madrzykowski, Daniel, and Nicholas Dow. Residential Flashover Prevention with Reduced Water Flow: Phase 1. UL Firefighter Safety Research Institute, April 2020. http://dx.doi.org/10.54206/102376/jegf7178.
Повний текст джерелаАнотація:
This study was designed to be an initial step to investigate the potential of low flow nozzles as part of a retrofit flashover prevention system in residential homes with limited water supplies. Not all homes have water supplies that can meet the needs of a residential sprinkler system. Current alter- natives, such as including a supplemental tank and pump, increase the cost of the system. These homes could benefit from an effective fire safety system with lower water supply requirements. The experiments in this study were conducted in a steel test structure which consisted of a fire room attached to a hallway in an L-shaped configuration. Three types of experiments were conducted to evaluate nozzles at different flow rates and under different fire conditions. The performance of the nozzles was compared to the performance of a commercially available residential sprinkler. The first set of experiments measured the distribution of the water spray from each of the nozzles and the sprinkler. The water spray measurements were made without the presence of a fire. The other two sets of experiments were fire experiments. The first set of fire experiments were designed to measure the ability of a water spray to cool a hot gas layer generated by a gas burner fire. The fire source was a propane burner which provided a steady and repeatable flow of heat into the test structure. Two water spray locations were examined, in the fire room and in the middle of the hallway. In each position, the burner was shielded from the water spray. The results showed that for equivalent conditions, the nozzle provided greater gas cooling than the sprinkler. The tests were conducted with a fire size of approximately 110 kW, and water flow rates in the range of 11 lpm (3 gpm) and 19 lpm (5 gpm). The second set of fire experiments used an upholstered sofa as the initial source of the fire with the water spray located in the same room. As a result of the compartment size and water spray distribution, the nozzle flowing water at 23 lpm (6 gpm) provided more effective suppression of the fire than the sprinkler flowing 34 lpm (9 gpm) did. The nozzle was similarly effective with the ignition location moved 1.0 m (3.2 ft) further away. However, the nozzle failed to suppress the fire with a reduced water flow rate of 11 lpm (3 gpm). The results of this limited study demonstrate the potential of low flow nozzles, directly flowing water on to the fuel surface, with the goal of preventing flashover. Additional research is needed to examine larger room sizes, fully furnished rooms, and shielded fires to determine the feasibility of a reduced water flow flashover prevention system.
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Brophy, Kenny, and Alison Sheridan, eds. Neolithic Scotland: ScARF Panel Report. Society of Antiquaries of Scotland, June 2012. http://dx.doi.org/10.9750/scarf.06.2012.196.
Повний текст джерелаАнотація:
The main recommendations of the Panel report can be summarised as follows: The Overall Picture: more needs to be understood about the process of acculturation of indigenous communities; about the Atlantic, Breton strand of Neolithisation; about the ‘how and why’ of the spread of Grooved Ware use and its associated practices and traditions; and about reactions to Continental Beaker novelties which appeared from the 25th century. The Detailed Picture: Our understanding of developments in different parts of Scotland is very uneven, with Shetland and the north-west mainland being in particular need of targeted research. Also, here and elsewhere in Scotland, the chronology of developments needs to be clarified, especially as regards developments in the Hebrides. Lifeways and Lifestyles: Research needs to be directed towards filling the substantial gaps in our understanding of: i) subsistence strategies; ii) landscape use (including issues of population size and distribution); iii) environmental change and its consequences – and in particular issues of sea level rise, peat formation and woodland regeneration; and iv) the nature and organisation of the places where people lived; and to track changes over time in all of these. Material Culture and Use of Resources: In addition to fine-tuning our characterisation of material culture and resource use (and its changes over the course of the Neolithic), we need to apply a wider range of analytical approaches in order to discover more about manufacture and use.Some basic questions still need to be addressed (e.g. the chronology of felsite use in Shetland; what kind of pottery was in use, c 3000–2500, in areas where Grooved Ware was not used, etc.) and are outlined in the relevant section of the document. Our knowledge of organic artefacts is very limited, so research in waterlogged contexts is desirable. Identity, Society, Belief Systems: Basic questions about the organisation of society need to be addressed: are we dealing with communities that started out as egalitarian, but (in some regions) became socially differentiated? Can we identify acculturated indigenous people? How much mobility, and what kind of mobility, was there at different times during the Neolithic? And our chronology of certain monument types and key sites (including the Ring of Brodgar, despite its recent excavation) requires to be clarified, especially since we now know that certain types of monument (including Clava cairns) were not built during the Neolithic. The way in which certain types of site (e.g. large palisaded enclosures) were used remains to be clarified. Research and methodological issues: There is still much ignorance of the results of past and current research, so more effective means of dissemination are required. Basic inventory information (e.g. the Scottish Human Remains Database) needs to be compiled, and Canmore and museum database information needs to be updated and expanded – and, where not already available online, placed online, preferably with a Scottish Neolithic e-hub that directs the enquirer to all the available sources of information. The Historic Scotland on-line radiocarbon date inventory needs to be resurrected and kept up to date. Under-used resources, including the rich aerial photography archive in the NMRS, need to have their potential fully exploited. Multi-disciplinary, collaborative research (and the application of GIS modelling to spatial data in order to process the results) is vital if we are to escape from the current ‘silo’ approach and address key research questions from a range of perspectives; and awareness of relevant research outside Scotland is essential if we are to avoid reinventing the wheel. Our perspective needs to encompass multi-scale approaches, so that ScARF Neolithic Panel Report iv developments within Scotland can be understood at a local, regional and wider level. Most importantly, the right questions need to be framed, and the right research strategies need to be developed, in order to extract the maximum amount of information about the Scottish Neolithic.
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Fahima, Tzion, and Jorge Dubcovsky. Map-based cloning of the novel stripe rust resistance gene YrG303 and its use to engineer 1B chromosome with multiple beneficial traits. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598147.bard.
Повний текст джерелаАнотація:
Research problem: Bread wheat (Triticumaestivum) provides approximately 20% of the calories and proteins consumed by humankind. As the world population continues to increase, it is necessary to improve wheat yields, increase grain quality, and minimize the losses produced by biotic and abiotic stresses. Stripe rust, caused by Pucciniastriiformisf. sp. tritici(Pst), is one of the most destructive diseases of wheat. The new pathogen races are more virulent and aggressive than previous ones and have produced large economic losses. A rich source for stripe-rust resistance genes (Yr) was found in wild emmer wheat populations from Israel. Original Project goals: Our long term goal is to identify, map, clone, characterize and deploy in breeding, novel wild emmer Yr genes, and combine them with multiple beneficial traits. The current study was aiming to map and clone YrG303 and Yr15, located on chromosome 1BS and combine them with drought resistance and grain quality genes. Positional cloning of YrG303/Yr15: Fine mapping of these genes revealed that YrG303 is actually allelic to Yr15. Fine genetic mapping using large segregating populations resulted in reduction of the genetic interval spanning Yr15 to less than 0.1 cM. Physical mapping of the YrG303/Yr15 locus was based on the complete chromosome 1BS physical map of wheat constructed by our group. Screening of 1BS BAC library with Yr15 markers revealed a long BAC scaffold covering the target region. The screening of T. dicoccoidesaccession-specific BAC library with Yr15 markers resulted in direct landing on the target site. Sequencing of T. dicoccoidesBAC clones that cover the YrG303/Yr15 locus revealed a single candidate gene (CG) with conserved domains that may indicate a role in disease resistance response. Validation of the CG was carried out using EMS mutagenesis (loss-of- function approach). Sequencing of the CG in susceptible yr15/yrG303 plants revealed three independent mutants that harbour non-functional yr15/yrG303 alleles within the CG conserved domains, and therefore validated its function as a Pstresistance gene. Evaluation of marker-assisted-selection (MAS) for Yr15. Introgressions of Yr15 into cultivated wheat are widely used now. Recently, we have shown that DNA markers linked to Yr15 can be used as efficient tools for introgression of Yr15 into cultivated wheat via MAS. The developed markers were consistent and polymorphic in all 34 tested introgressions and are the most recommended markers for the introgression of Yr15. These markers will facilitate simultaneous selection for multiple Yr genes and help to avoid escapees during the selection process. Engineering of improved chromosome 1BS that harbors multiple beneficial traits. We have implemented the knowledge and genetic resources accumulated in this project for the engineering of 1B "super-chromosome" that harbors multiple beneficial traits. We completed the generation of a chromosome including the rye 1RS distal segment associated with improved drought tolerance with the Yr gene, Yr15, and the strong gluten allele 7Bx-over-expressor (7Bxᴼᴱ). We have completed the introgression of this improved chromosome into our recently released variety Patwin-515HP and our rain fed variety Kern, as well as to our top breeding lines UC1767 and UC1745. Elucidating the mechanism of resistance exhibited by Yr36 (WKS1). The WHEAT KINASE START1 (WKS1) resistance gene (Yr36) confers partial resistance to Pst. We have shown that wheat plants transformed with WKS1 transcript are resistant to Pst. WKS1 is targeted to the chloroplast where it phosphorylates the thylakoid-associatedascorbateperoxidase (tAPX) and reduces its ability to detoxify peroxides. Based on these results, we propose that the phosphorylation of tAPX by WKS1 reduces the ability of the cells to detoxify ROS and contributes to cell death. Distribution and diversity of WKS in wild emmer populations. We have shown that WKS1 is present only in the southern distribution range of wild emmer in the Fertile Crescent. Sequence analysis revealed a high level of WKS1 conservation among wild emmer populations, in contrast to the high level of diversity observed in NB-LRR genes. This phenomenon shed some light on the evolution of genes that confer partial resistance to Pst. Three new WKS1 haplotypes displayed a resistance response, suggesting that they can be useful to improve wheat resistance to Pst. In summary, we have improved our understanding of cereals’ resistance mechanisms to rusts and we have used that knowledge to develop improved wheat varieties.
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Cahaner, Avigdor, Susan J. Lamont, E. Dan Heller, and Jossi Hillel. Molecular Genetic Dissection of Complex Immunocompetence Traits in Broilers. United States Department of Agriculture, August 2003. http://dx.doi.org/10.32747/2003.7586461.bard.
Повний текст джерелаАнотація:
Objectives: (1) Evaluate Immunocompetence-OTL-containing Chromosomal Regions (ICRs), marked by microsatellites or candidate genes, for magnitude of direct effect and for contribution to relationships among multiple immunocompetence, disease-resistance, and growth traits, in order to estimate epistatic and pleiotropic effects and to predict the potential breeding applications of such markers. (2) Evaluate the interaction of the ICRs with genetic backgrounds from multiple sources and of multiple levels of genetic variation, in order to predict the general applicability of molecular genetic markers across widely varied populations. Background: Diseases cause substantial economic losses to animal producers. Emerging pathogens, vaccine failures and intense management systems increase the impact of diseases on animal production. Moreover, zoonotic pathogens are a threat to human food safety when microbiological contamination of animal products occurs. Consumers are increasingly concerned about drug residues and antibiotic- resistant pathogens derived from animal products. The project used contemporary scientific technologies to investigate the genetics of chicken resistance to infectious disease. Genetic enhancement of the innate resistance of chicken populations provides a sustainable and ecologically sound approach to reduce microbial loads in agricultural populations. In turn, animals will be produced more efficiently with less need for drug treatment and will pose less of a potential food-safety hazard. Major achievements, conclusions and implications:. The PI and co-PIs had developed a refined research plan, aiming at the original but more focused objectives, that could be well-accomplished with the reduced awarded support. The successful conduct of that research over the past four years has yielded substantial new information about the genes and genetic markers that are associated with response to two important poultry pathogens, Salmonella enteritidis (SE) and Escherichia coli (EC), about variation of immunocompetence genes in poultry, about relationships of traits of immune response and production, and about interaction of genes with environment and with other genes and genetic background. The current BARD work has generated a base of knowledge and expertise regarding the genetic variation underlying the traits of immunocompetence and disease resistance. In addition, unique genetic resource populations of chickens have been established in the course of the current project, and they are essential for continued projects. The US laboratory has made considerable progress in studies of the genetics of resistance to SE. Microsatellite-marked chromosomal regions and several specific genes were linked to SE vaccine response or bacterial burden and the important phenomenon of gene interaction was identified in this system. In total, these studies demonstrate the role of genetics in SE response, the utility of the existing resource population, and the expertise of the research group in conducting such experiments. The Israeli laboratories had showed that the lines developed by selection for high or low level of antibody (Ab) response to EC differ similarly in Ab response to several other viral and bacterial pathogens, indicating the existence of a genetic control of general capacity of Ab response in young broilers. It was also found that the 10w-Ab line has developed, possibly via compensatory "natural" selection, higher cellular immune response. At the DNA levels, markers supposedly linked to immune response were identified, as well as SNP in the MHC, a candidate gene responsible for genetic differences in immunocompetence of chickens.
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Mitchell, Brian G., Amir Neori, Charles Yarish, D. Allen Davis, Tzachi Samocha, and Lior Guttman. The use of aquaculture effluents in spray culture for the production of high protein macroalgae for shrimp aqua-feeds. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7597934.bard.
Повний текст джерелаАнотація:
The FAO has projected a doubling in world demand for seafood during the 21 ed from aquaculture of marine fish and shrimps fed primarily on fishmeal-based aquafeeds. However, current practices of high intensity monoculture of shrimp in coastal ponds and fish in offshore pens have been strongly criticized as being ecologically and socially unsustainable. This view derives from un- checked eutrophication of coastal marine ecosystems from fish farm effluents, and the destruction of coastal estuarine ecosystems by shrimp farm constructions, plus aquaculture’s reliance on wild-caught small fish - which are excellent food for humans, but instead are rendered into fishmeal and fish oil for formulating aquafeeds. Fishmeal-sparing and waste- reduction aquafeeds can only delay the time when fed aquaculture product are priced out of affordability for most consumers. Additionally, replacement of fishmeal protein and fish oil by terrestrial plant sources such as soybean meal and oil directly raises food costs for human communities in developing nations. New formulations incorporating sustainably-produced marine algal proteins and oils are growing in acceptance as viable and practical alternatives. This BARD collaborative research project investigated a sustainable water-sparing spray/drip culture method for producing high-protein marine macrophyte meals for incorporation into marine shrimp and fish diets. The spray culture work was conducted at laboratory-scale in the USA (UCSD-SIO) using selected Gracilariaand Ulvastrains isolated and supplied by UCONN, and outdoors at pilot-scale in Israel (IOLR-NCM) using local strains of Ulvasp., and nitrogen/phosphorus-enriched fish farm effluent to fertilize the spray cultures and produce seaweed biomass and meals containing up to 27% raw protein (dry weight content). Auburn University (USA) in consultation with TAMUS (USA) used the IOLR meals to formulate diets and conduct marine shrimp feeding trials, which resulted in mixed outcomes, indicating further work was needed to chemically identify and remove anti-nutritional elements present in the IOLR-produced seaweed meals.