A Reconfigurable Three-Phase Dual-Active-Bridge DC-DC Converter Designed for Wide-Range High-Efficiency Operation

Benzofurans are everywhere in nature and they have been extensively studied by medicinal chemists over the years because of their chemotherapeutic and physiological properties. Herein, we describe a strategy that can be used to access elaborate benzo-2-carboxamide derivatives, which involves a synthetic sequence of 8-aminoquinoline directed C–H arylations followed by transamidations. For the directed C–H arylations, Pd catalysis was used to install a wide range of aryl and heteroaryl substituents at the C3 position of the benzofuran scaffold in high efficiency. Directing group cleavage and further diversification of the C3-arylated benzofuran products were then achieved in a single synthetic operation through the utilization of a two-step transamidation protocol. By bocylating the 8-aminoquinoline amide moiety of these products, it proved possible to activate them towards aminolysis with different amine nucleophiles. Interestingly, this aminolysis reaction was found to proceed efficiently without the need of any additional catalyst or additive. Given the high efficiency and modularity of this synthetic strategy, it constitute a very attractive approach for generating structurally-diverse collections of benzofuran derivatives for small molecule screening.

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To the 70th anniversary of World Meteorological Organization. Scientific and technical cooperation of Hydrometeorological Center of the USSR/Russia in the Programs of World Meteorological Organization

Hydrometeorological research and forecasting ◽

10.37162/2618-9631-2020-4-117-138 ◽

2020 ◽

pp. 117-138

Author(s):

S.V. Borshch ◽

◽

R.M. Vil’fand ◽

D.B. Kiktev ◽

V.M. Khan ◽

...

Keyword(s):

Environmental Monitoring ◽

High Efficiency ◽

World Meteorological Organization ◽

70Th Anniversary ◽

Technical Level ◽

Technical Cooperation ◽

Wide Range

The paper presents the summary and results of long-term and multi-faceted experience of international scientific and technical cooperation of Hydrometeorological Center of Russia in the field of hydrometeorology and environmental monitoring within the framework of WMO programs, which indicates its high efficiency in performing a wide range of works at a high scientific and technical level. Keywords: World Meteorological Organization, major WMO programs, representatives of Hydrometeorological Center of Russia in WMO

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Integrated Design and Multi-Objective Optimization of a Single Stage Heat-Pump Turbocompressor

Volume 3B: 39th Design Automation Conference ◽

10.1115/detc2013-12180 ◽

2013 ◽

Author(s):

J. Schiffmann

Keyword(s):

Design Optimization ◽

High Efficiency ◽

Integrated Design ◽

Heat Pumps ◽

Small Scale ◽

Multi Objective Optimization ◽

Design Constraints ◽

Multi Objective ◽

Wide Range ◽

Standard Design

Small scale turbomachines in domestic heat pumps reach high efficiency and provide oil-free solutions which improve heat-exchanger performance and offer major advantages in the design of advanced thermodynamic cycles. An appropriate turbocompressor for domestic air based heat pumps requires the ability to operate on a wide range of inlet pressure, pressure ratios and mass flows, confronting the designer with the necessity to compromise between range and efficiency. Further the design of small-scale direct driven turbomachines is a complex and interdisciplinary task. Textbook design procedures propose to split such systems into subcomponents and to design and optimize each element individually. This common procedure, however, tends to neglect the interactions between the different components leading to suboptimal solutions. The authors propose an approach based on the integrated philosophy for designing and optimizing gas bearing supported, direct driven turbocompressors for applications with challenging requirements with regards to operation range and efficiency. Using previously validated reduced order models for the different components an integrated model of the compressor is implemented and the optimum system found via multi-objective optimization. It is shown that compared to standard design procedure the integrated approach yields an increase of the seasonal compressor efficiency of more than 12 points. Further a design optimization based sensitivity analysis allows to investigate the influence of design constraints determined prior to optimization such as impeller surface roughness, rotor material and impeller force. A relaxation of these constrains yields additional room for improvement. Reduced impeller force improves efficiency due to a smaller thrust bearing mainly, whereas a lighter rotor material improves rotordynamic performance. A hydraulically smoother impeller surface improves the overall efficiency considerably by reducing aerodynamic losses. A combination of the relaxation of the 3 design constraints yields an additional improvement of 6 points compared to the original optimization process. The integrated design and optimization procedure implemented in the case of a complex design problem thus clearly shows its advantages compared to traditional design methods by allowing a truly exhaustive search for optimum solutions throughout the complete design space. It can be used for both design optimization and for design analysis.

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Low Power Cusped Field Thruster Developed for the Space-Borne Gravitational Wave Detection Mission in China

Applied Sciences ◽

10.3390/app11146549 ◽

2021 ◽

Vol 11 (14) ◽

pp. 6549

Author(s):

Hui Liu ◽

Ming Zeng ◽

Xiang Niu ◽

Hongyan Huang ◽

Daren Yu

Keyword(s):

Low Power ◽

Gravitational Wave ◽

Attitude Control ◽

High Efficiency ◽

Experimental Investigations ◽

Attitude Control System ◽

Gravitational Wave Detection ◽

Wave Detection ◽

Wide Range ◽

Institute Of Technology

The microthruster is the crucial device of the drag-free attitude control system, essential for the space-borne gravitational wave detection mission. The cusped field thruster (also called the High Efficiency Multistage Plasma Thruster) becomes one of the candidate thrusters for the mission due to its low complexity and potential long life over a wide range of thrust. However, the prescribed minimum of thrust and thrust noise are considerable obstacles to downscaling works on cusped field thrusters. This article reviews the development of the low power cusped field thruster at the Harbin Institute of Technology since 2012, including the design of prototypes, experimental investigations and simulation studies. Progress has been made on the downscaling of cusped field thrusters, and a new concept of microwave discharge cusped field thruster has been introduced.

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Quadrature Voltage Compensation in the Isolated Multi-Modular Converter

Energies ◽

10.3390/en14030529 ◽

2021 ◽

Vol 14 (3) ◽

pp. 529

Author(s):

Cristian Verdugo ◽

Jose Ignacio Candela ◽

Pedro Rodriguez

Keyword(s):

Control Strategy ◽

Phase Voltage ◽

Multilevel Converters ◽

Photovoltaic Panels ◽

Circulating Current ◽

Three Phase ◽

Voltage Compensation ◽

Wide Range ◽

Modular Converter ◽

The Impact

Series connections of modules in cascaded multilevel converters are prone to power imbalances due to voltage differences on their DC side. When modules are connected to direct current (DC) sources, such as photovoltaic panels, the capability of withstanding power imbalances is crucial for generating the maximum power. In order to provide a possible solution for this requirement, this paper proposes a control strategy called Quadrature Voltage Compensation, which allows a wide range of power imbalances. The proposed control strategy regulates the power by introducing a circulating current between the arms and a phase angle in the output voltage. The impact of the circulating current and its effect on the phase voltage are studied. To highlight the features of the proposed strategy, an analytical model based on vector superposition is also described, demonstrating the strong capability of tolerating power differences. Finally, to validate the effectiveness of the Quadrature Voltage Compensation, simulation and experimental results are presented for a three-phase isolated multi-modular converter.

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