High-efficiency System Research Articles

The Impact of Climate Change and Window Parameters on Energy Demand and CO2 Emissions in a Building with Various Heat Sources

This article presents an original study on the impact of climate change and the area of windows Awi (factor X1), the thermal transmittance coefficient of windows Uwi (factor X2), and the coefficient of total solar transmittance factor of the glazing ggl (factor X3) on the index of annual usable energy demand for heating EUH (function Y) of a single-family residential building in the climatic conditions of Bialystok (Poland), which were loaded with an equal gradual increase in average monthly external temperature by Δθe,n (factor X4). Based on the results of the computational experiment, a deterministic mathematical model of this dependence was developed, and the effects of selected factors on the Y function were analyzed for the considered climatic conditions. Moreover, in cases of selected variants, the influence of the energy source on the amount of final energy used and CO2 emissions was studied. It was found that an increase in the average monthly external temperature reduces the EUH of the tested building by 8.4% per every 1 °C of increase in Δθe,n. The reduction in CO2 emissions as a result of climate change is visible for systems with low efficiency and high emission factors (wood boiler), while in the case of pro-ecological high-efficiency systems (with a ground-source pump heat) it is inappreciable. Due to the need to decarbonize buildings, knowledge about the impact of the properties of windows, which are the weakest element in terms of heat loss through the building envelope, as well as the type of heat source on heat demand and CO2 emissions, is very important for engineers and designers when making the correct decisions.

Mechanistic study on the synergy of cold plasma and sulfate radical in the degradation of azo and triarylmethane dyes using density functional theory

The activation of persulfate using cold plasma and the synergy of plasma-generated reactive species and SO4•− in mineralization of organic dyes were assessed. In this regard, solutions of crystal violet (CV) as a triarylmethane dye and methyl orange (MO) as an azo dye, were treated with cold plasma, UV-C-activated sulfate radicals, and their combination. The achieved results showed 95% TOC removal, a synergy factor of 1.3 and an energy yield of 1.68 (g kWh−1) for the combined system. The contribution of oxidant species in CV (SO4•− > O2•- > •OH) and MO (SO4•−> O2•- >1O2) degradation was explored. Moreover, analysis of degradation products and density functional theory (DFT) calculations were adopted to find the degradation mechanism based on the minimum energy pathway. Experimental and DFT results revealed that while radical and nucleophilic pathways were the drivers of CV degradation, the electrophilic attack of oxidants was a more plausible mechanism for MO degradation. Additionally, a comparison of the results of different DFT methods with experimental values showed that the Kohn–Sham DFT yielded more accurate results compared to recommended double hybrid methods. Analysis of a treated real wastewater revealed that the background constituents had negligible effects on MO and CV degradation. The high TOC removal efficiency of the combined system suggests its feasibility for treating wastewater from fertilizer and pharmaceutical production facilities.

Wideband High-Efficiency and Simple-Structured Rectifying Metasurface

In this communication, a wideband rectifying metasurface for RF energy harvesting is proposed. By virtue of the two resonant modes of the paralleling metasurface resonator, it is not only the wideband feature can be obtained but also enables direct impedance matching between the high impedance diode and high impedance metasurface, eliminating impedance matching. A DC feed structure is proposed where each unit of the metasurface is connected by the chip inductors, and DC energy can be combined and exported directly, eliminating power combining networks. Then, A 6 × 6 array was designed and fabricated. Experimental results show that the proposed rectifying metasurface system operates at 5.32–6.66 GHz with a fractional bandwidth of 22.4%, and the peak efficiency is 74.5%. As a contribution to this work, RF energy on a broader frequency range can be captured by the proposed system with higher system efficiency, while maintaining a simple structure. This shows its great potential in wireless power transfer and indoor RF energy harvesting.

Magnetic polyphosphazene@Au particles as substrates for multiple-detection of immunoproteins by surface-enhanced Raman spectroscopy

Au coated magnetic polyphosphazene (MPCTP) composite particles (MPCTP@Au) were fabricated with sensitive SERS activity. The MPCTP particles were generated by coating polyphosphazene on Fe3O4 nanoparticles through precipitation polycondensation of hexachlorocyclotriphosphazene and phloroglucinol. MPCTP@Au composite particles were obtained by deposition of Au nanoparticles on MPCTP by the reduction of HAuCl4. The size and the thickness of the Au shell can be controlled by varying the amount of HAuCl4. The magnetic core endowed the composite particles with good magnetic responsiveness, which allowed the analyte to be enriched and separated from the complex matrix, and significantly simplifying the sample pretreatment procedure. The SERS activity of MPCTP@Au composite particles were evaluated by DTNB as model Raman reporter, and the limits of detection (LOD) of DTNB was 10-8 mol/L. A high efficient SERS immunoassay system based on the MPCTP@Au substrates for the detection of immunoproteins was developed. Human IgG and rabbit IgG were quantitatively determinated simultaneously by this immunoassay system. The quantitative determination of the immunoglobulin G (IgG) was achieved and the LOD of human IgG, rabbit IgG and the mixture of human IgG and rabbit IgG were as low as 10 fg/mL, 100 pg/mL and 1 ng/mL, respectively. The results showed that the MPCTP@Au composite particles have broad application prospects as high performance SERS active substrates for immunoprotein analysis.

Robust Parity-Time-Symmetric WPT System With Reduced Switching-Frequency and Improved Step-Down Conversion Ratio

In this paper, combining the phase synchronization method (PSM) and high harmonic operation (HHO), a novel parity-time(PT)-symmetric wireless power transfer (WPT) system with reduced switching frequency and improved step-down conversion ratio is proposed, where the power transferred to receiver side is carried by the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> th harmonic. We demonstrate that constant current (CC) and constant voltage (CV) independent of coupling coefficient and load resistance can also be obtained without wireless communication and additional dc-dc converters. Here, a new implementation of a negative resistor based on the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> th harmonic operation is proposed, which is a necessary condition of a PT-based system. In contrast to the standard PT-based system with the same resonant frequency, the switching frequency is reduced to 1/n due to the use of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> th harmonic, thereby realizing low switching losses and high system efficiency. Besides, an inherently improved step-down conversion ratio can be obtained. A prototype with a 6 A charging current and a 36 V charging voltage is built to verify the feasibility of the proposed method.

Bidirectional inductive underwater wireless power transfer converter with variable structure

The undersea sensor networks have an important function in marine resource exploration. To prolong the lifetime of the sensor networks, a bidirectional inductive underwater wireless power transfer (BI-UWPT) system with variable structure is proposed. With the proposed system, the autonomous underwater vehicle (AUV) could receive energy from the undersea docking station and transmit energy to the undersea sensor networks. The two full bridge topologies and the SS compensation networks are adopted in the system to achieve the bidirectional power transfer. To achieve bidirectional energy transmission of different power levels, two different operating frequencies and variable compensation capacitors are employed by the AUV. The system mathematical model is also presented. To verify the theoretical analysis, a 432 W simulation model when the AUV receiving electric energy and a 96 W simulation model when the AUV transmitting electric energy are constructed, respectively. The theoretical analysis is verified by the simulation results. Simulation results show that the variable compensation networks can obtain high transfer efficiency of the BI-UWPT system.

Evaluation of Heat Pump Operation in a Single-Family House

Abstract Since decarbonization of the energy sector is among the top priorities in the EU, with ambitious targets of carbon neutrality until 2050, the energy efficiency of the building stock and the use of renewables are those directions, which can bring the most considerable input towards the achievement of these goals. However, it is not always obvious how to efficiently combine different aspects of low energy demand, availability of renewables, part load operation conditions etc. The results of dynamic IDA ICE simulations highlight that the introduction of renewable low-carbon energy sources should be thoroughly coupled with building energy systems and only their full compatibility can give a high efficiency of the entire energy supply system of the building. Analysing simulation data, it was concluded that for low-energy buildings, heat pumps would not always show higher COP values, compared to buildings with higher energy demand. Ground source heat pump (GSHP) will not always be more efficient than air source heat pump (ASHP). If the ground/groundwater temperature is lower than 10 °C, for GSHP it will be almost impossible to over-compete ASHP within the same system. While COP with radiators and underfloor heating differs only by 10 %, both for ASHP and GSHP.

Improving the Performance of Layer-by-Layer Processed Organic Solar Cells via Introducing a Wide-Bandgap Dopant into the Upper Acceptor Layer.

The layer-by-layer (LbL) solution-processed organic solar cells (OSCs) are conductive to achieve vertical phase separation, tunable donor-acceptor (D/A) interfaces, and favorable charge-transport pathways. In this work, a wide-bandgap component poly(9-vinylcarbazole) (PVK) is added to the upper electron acceptor layer to improve the performance of LbL-processed OSCs. Results show that the PVK component can adjust the film morphology, dope the electron acceptor, increase the electron concentration, and improve charge transport. Such n-type doping is verified by Seebeck coefficient measurement, ultraviolet photoelectron spectroscopy, and electron paramagnetic resonance characterization. In addition, the fluorescence intensity and exciton lifetime of the PVK-doped acceptor film are increased, thus being beneficial for exciton diffusion to the D/A interface. Therefore, the power conversion efficiency (PCE) of LbL OSCs increases when 2.50 wt.% PVK is employed in the electron acceptor layer of commonly-used high-efficiency system and a maximum value of 19.05% can be achieved. The role of PVK played in the active layer is different from those of additives and ternary components reported previously, so the results provide an alternative way to enhance the device performance of LbL-processed OSCs.

High accurate and modulation transparent frequency offset compensation scheme using data-aided feedback structure in coherent optical communication systems

The high-order modulation format has the advantages of high spectral efficiency and large system capacity. However, the traditional frequency offset estimation and compensation algorithms, such as fast Fourier transform-based frequency offset estimation (FFT-FOE) that relies on a large number of complex FFT operations and differential frequency offset estimation (Diff-FOE) that relies on finite phase difference between adjacent symbols, are difficult to meet the frequency offset estimation requirements for any high-order modulation format. In this work, a novel FOE scheme using QPSK training symbols aided feedback structure is proposed. The performance of the proposed FOE scheme is evaluated in a polarization multiplexing QPSK-aided 32/64-quadrature amplitude modulation (QAM) simulation platforms with a symbol rate of 28 GBaud. The results show that has the technical advantages of low complexity, suitable for arbitrarily high-order modulation, tolerance for laser phase noise and wide tracking frequency offset range.

Configurations and Operation Methods of Diesel-Based Solid Oxide Fuel Cell System

Solid oxide fuel cell (SOFC) can use a wide variety of carbon-based fuels. Diesel can act as a high-quantity fuel because of its high heat value and ease of transport. In this study, three different system configurations were proposed by a model in ASPEN PLUS V12 and fitted by data measured in the large size cell. The effects of key operation parameters, including reforming temperature, steam-to-carbon ratio (S/C) and recycling rate of the anode off-gas, were studied, which were characterized by the system efficiency and output power. As a result, the highest system efficiency was gotten with a water condenser and an anode off-gas recycling module in the system. The best operation method occurs when the thermal load of the diesel reformer is compensated by the heat released by anode off-gas combustion. This research will lay a theoretical foundation for the upcoming design of a physical diesel-based SOFC system.

ANALYSIS OF EFFICIENCY OF HORIZONTAL WELLS WITH MULTI-STAGE HYDRAULIC FRACTURING ON THE EXAMPLE OF KONDINSKOYE FIELD

In the structure of potential oil reserves in Western Siberia, the share of hard-to-recover reserves (HRR) is growing. At the same time, a significant share of these reserves is concentrated in low-permeability reservoirs. Horizontal wells using multi-stage hydraulic fracturing are the basis of technological solutions used for cost-effective development of low-permeability reservoirs by Russian oil and gas producers [1-4]. Due to the high efficiency of the subsea development systems with MSHF, oil production from such facilities exceeds oil production from traditional reservoirs and accounts for more than 60 % of the total oil production of the Company's fields [5]. The following characteristics are identified as the key parameters of the horizontal section, the number of hydraulic fractures, as well as the specific weight of the injected proppant at the frac stage. The decisions approved as part of the design documents for the development of facilities with TPP indicate a tendency to increase the length of the horizontal hole and the number of frac operations with a decrease in the specific mass of proppant on the port. The article examines the impact of these characteristics on the technological efficiency of wells. The purpose of the work is to assess the feasibility of increasing the technological complexity of HW with multi-stage hydraulic fracturing of the MSHF formation in the form of increasing the number of stages and length of the horizontal hole, as well as the specific mass of proppantane in the example of the AS10/1 Kondinskoye field development target. Within the framework of the study, three types of HW with MSHF were identified, the technological effectiveness of which was assessed in two ways. The first method consisted in comparing the magnitudes of the dimensionless productivity coefficient Jd (d. units) of three different types of wells with a horizontal end in relation to directional wells (FWS with frac) of the environment. Taking into account the similarity of the geological conditions of the neighboring wells, this method made it possible to assess how effectively the completion of the horizontal wells under study was completed. The multiplicity assessment methodology was developed by RN-BashNIPIneft LLC [6]. The second method was to compare the ratio of dimensionless productivity factor to the specific weight of proppant Jd/Mpr _ specific of the identified types of HW with multi-stage hydraulic fracturing (MSHR). This approach made it possible to take into account the effective thickness and permeability of the formation in the well drilling zone, as well as the weight distribution of the injected proppant. The results showed that if the length of the horizontal hole is constant, an increase in the number of frac stages while reducing the proppant weight on the port is impractical. Confirmation was also obtained based on statistical data that there is a relationship between the cumulative fluid withdrawal and the weight of the injected proppant. It has been established that drilling HW with multi-stage hydraulic fracturing of the (MSHF) formation of the most common type (1000 m, 10 stages) is not optimal for the study target: for a length of 1000 m, the maximum number of stages should be limited to 7–8 units per well. Further monitoring and analysis of production wells with horizontal termination is recommended to collect more statistical data and compare them over time.

Thermal hydraulic design and mass optimization of a 100-kWe S-CO2 cooled Mars-surface fission reactor system

Fission reactor with electrical power of 100 kW to megawatt is a promising power option for upcoming deep space exploration. To reduce the number of space launches and the costs, it is necessary to design an energy supply system coupling fission reactor with energy conversion system of high efficiency and compactness. The combination of gas-cooled fast reactor and supercritical carbon dioxide (S-CO2) Brayton cycle has the advantages of simple system layout, compact structure and high thermal efficiency.This paper aims to carry out researches on the thermal hydraulic design and mass optimization of 100kWe reactor system for Mars-surface application.An analysis code which includes thermodynamic models for different components in the system, as well as mass evaluation models for radiator, recuperator and reactor, is developed and validated to provide an analysis tool. An S-CO2 Brayton cycle directly cooled reactor system is proposed, which applies Tube-In-Duct fuel assembly to make up the core and heat pipe radiator as heat rejection system. The thermal hydraulic evaluation of the reactor core, thermodynamic performance evaluation as well as overall mass evaluation of the whole system are carried out to achieve an optimized 100kWe fission reactor system for Mars surface with minimum mass. The optimal design has an operating pressure of 16 MPa, core outlet temperature of 600 °C, radiator panel area of 120 m2 and an overall mass of 1862.98 kg considering the reactor and key components of Brayton cycle. S-CO2 Brayton cycle directly cooled reactor system has a comparable specific mass as He-Xe cooled reactor with lower operating temperature, which is beneficial for material selection and provides another option for space reactor development.

Comparison of three different control strategies for load-change and attenuation of solid oxide fuel cell system

Solid oxide fuel cell (SOFC) with a lot of advantages, such as high efficiency, low emission and great fuel compatibility, has broad application prospects in many fields. However, an appropriate control strategy is necessary for SOFC systems, which could not only maintain high system efficiency during load-change, but also supplement power after attenuation to extend system service life. In the article, three different control strategies are proposed, in which fuel flow, fuel utilization and cell voltage are controlled as constants respectively. The performance and applicability of strategies for load-change and cell degradation are evaluated through experiment data and simulations. Meanwhile, stack temperature, voltage, fuel utilization and efficiency are selected as main constraints to analyze the application scope of strategies. And in load increasing process of a 1 kW SOFC combined heat and power (CHP) system fed with methanol, the strategies are adopted to verify their effectiveness.

A Review of Single-Stage Multiport Inverters for Multisource Applications

Conventional power electronic interfaces for multisource applications always need multiple conversion stages as intermediate dc-dc power conversion stages are inevitably installed for matching the different dc voltage levels and regulating the power distribution among dc sources. Dually, single-stage multiport inverter for multisource applications enables direct connection from the dc source to ac side without an extra conversion stage and has witnessed an upward trend in recent years. The salient advantages of single-stage multiport inverters comprise fewer power losses, fewer passive filters, and higher system efficiency. To capture the advancement in the field, the article reviews various single-stage multiport inverters for multisource applications, offers a comprehensive understanding of the current development of this configuration, and provides an insightful forward look at potential research issues of single-stage multiport inverters. This article presents various state-of-art single-stage multiport topologies as well as their applications and comparisons. In addition, systemic topology derivation methods of single-stage multiport inverters are discussed to provide inspiration for exploring new topologies. Moreover, the main challenging issues of this topology such as modulation, control, and energy management strategies are analyzed and summarized. Finally, some open questions and future trends of single-stage multiport inverters are also discussed to motivate future research and explore new alternatives.

Sequential delivery of PD-1/PD-L1 blockade peptide and IDO inhibitor for immunosuppressive microenvironment remodeling via an MMP-2 responsive dual-targeting liposome.

Intelligent responsive drug delivery system opens up new avenues for realizing safer and more effective combination immunotherapy. Herein, a kind of tumor cascade-targeted responsive liposome (NLG919@Lip-pep1) is developed by conjugating polypeptide inhibitor of PD-1 signal pathway (AUNP-12), which is also a targeted peptide that conjugated with liposome carrier through matrix metalloproteinase-2 (MMP-2) cleavable peptide (GPLGVRGD). This targeted liposome is prepared through a mature preparation process, and indoleamine-2,3-dioxygenase (IDO) inhibitor NLG919 was encapsulated into it. Moreover, mediated by the enhanced permeability and retention effect (EPR effect) and AUNP-12, NLG919@Lip-pep1 first targets the cells that highly express PD-L1 in tumor tissues. At the same time, the over-expressed MMP-2 in the tumor site triggers the dissociation of AUNP-12, thus realizing the precise block of PD-1 signal pathway, and restoring the activity of T cells. The exposure of secondary targeting module II VRGDC-NLG919@Lip mediated tumor cells targeting, and further relieved the immunosuppressive microenvironment. Overall, this study offers a potentially appealing paradigm of a high efficiency, low toxicity, and simple intelligent responsive drug delivery system for targeted drug delivery in breast cancer, which can effectively rescue and activate the body's anti-tumor immune response and furthermore achieve effective treatment of metastatic breast cancer.

비반전 동기 벅-부스트 컨버터의 CRM 제어

Buck-Boost Converter is a non-insulated Converter with a wide input range and could receive various voltage as an input However, as research for high efficiency of power conversion system progresses, the need to reduce semiconductor losses is increased. Buck-Boost Converter has a disadvantage in that a high conduction losses and a switching losses due to a forward voltage drop of diode. In this paper, the reduction of conduction losses was verified by comparing conduction losses of Synchronous Buck-Boost Converter and conduction losses of conventional Buck-Boost Converter, and the application of CRM(Critical Conduction Mode) control was demonstrated through experiments.

METHOD OF CONSTRUCTING HARDWARE ARCHITECTURE FOR COMPUTER VISION SYSTEM BASED ON FPGA

In this work, the methodology of hardware architecture development for computer vision systems based on programmable logic, in particular FPGA, is considered. In the work, the methods of developing architectures for computer vision are studied and the advantages of using FPGA compared to traditional general-purpose processors are established. The paper also considers the main aspects of hardware design on FPGA, in particular, the selection of a suitable development tool, logic design, synthesis, and validation of the developed hardware. The capabilities of FPGAs in providing high performance and efficiency of computer vision systems have been investigated, which makes them attractive and popular for use in visual systems. We discover that FPGA technology offers a high degree of flexibility and configurability, allowing for the creation of custom hardware architectures that can be tailored to specific computer vision applications. In addition, to studying the benefits of using FPGA technology for computer vision, we also consider the main aspects of hardware design on FPGA, including the selection of a suitable development tool, logic design, synthesis, and validation of the developed hardware. By carefully considering these aspects, we can ensure that the hardware architecture we develop is both efficient and effective. Our research shows that the capabilities of FPGAs in providing high performance and efficiency of computer vision systems are truly remarkable. This makes them an attractive choice for use in visual systems, particularly in scenarios where high speed and accuracy are critical. Overall, our work serves to shed light on the many benefits of FPGA technology for computer vision and lays the foundation for further research and development in this exciting field.

Optimized Resonant Network Design for High Energy Transfer Efficiency of the WPT System

This paper proposes an active resonant network based on variable resonant capacitances to improve the operating performance of the LCC-S compensated topology in the wireless power transfer (WPT) system for electric vehicles under coil-misaligned conditions. By adjusting the series and parallel compensation capacitances on the transmitting side, the output voltage can be kept constant and the energy transfer efficiency can be improved under different coil offsets. The switch-controlled capacitors (SCCs) are used to change the compensation capacitances continuously. To find the proper compensation capacitances to achieve the excellent performance of the system, the optimization algorithm is applied, and the corresponding digital control strategy is described to regulate the equivalent capacitances of SCCs. Experimental results with a 2.7 kW power scale show that the output voltage is constant, and the operating efficiency is always over 90% in the WPT system with an active resonant network under different misalignment conditions. In addition, the system is delivering an equal amount of energy for all misalignments within the range of 80 mm, which improves the expected value of transferred energy by about 29%.

Research on voltage comprehensive compensation system and control strategy of high-speed railway traction network

High-speed railway, as one of the most important forms of transportation, have been developed rapidly throughout the world. As the people’s living condition improves, the energy demand in China’s transport sector has grown dramatically and will keep increasing in the short term. In order to support the realization of ’ energy conservation ’ vision, it is urgent to adopt energy technology to change the structure of traditional high-speed railway system and realize the green, high efficiency and high elasticity transformation of high-speed railway system. High-speed railway will cause voltage fluctuation of the traction network during driving, which may affect the safety and reliability of high-speed railway in severe cases. In order to improve the voltage fluctuation of traction network caused by high-speed railway, this paper proposes a comprehensive voltage compensation system (VCCS) and its control strategy for high-speed railway traction network. Firstly, the causes of voltage fluctuation in traction network are analyzed, and the existing compensation methods at home and abroad are introduced. Then, the topology and compensation principle of high-speed railway traction network voltage compensation system are introduced, and the corresponding control strategy is proposed. Finally, the correctness of the theoretical analysis is verified by simulation experiments. The experimental results show that the VCCS proposed in this paper can ensure that the high-speed train can maintain full power operation under various typical working conditions, and effectively improve the voltage fluctuation of the traction network.

Operational characteristics of a free-piston Stirling generator with resonant self-circulating heat exchangers

Heat transfer is one of the most critical issues faced by free-piston Stirling generators (FPSGs) during power amplification, and the emergence of resonant self-circulating heat exchangers offers an alternative solution. In this study, a high-power FPSG with resonant self-circulating heat exchangers has been numerically studied using commercial software SAGE and thermoacoustic post-processing. The principle feasibility and operational characteristics of the proposed system with different loop lengths are verified based on comparative analysis with the Component Test Power Convertor. Results show that introducing a self-circulating heat exchanger can achieve high-power heat transfer through a steady flow. However, it results in a significant degradation in the performance of the FPSG, where the acoustic power loss in the loop is the most critical cause. The pump used to generate the steady flow also requires additional power consumption. Furthermore, systems with shorter loops of non-integer multiples of wavelength have higher system efficiency and lower pump power consumption. For example, the output electric power can achieve 9.9 kW (corresponding to a thermal-to-electric efficiency of 18.8%) when the loop length is 2 m, where the power consumption of the pump is only 0.19 kW. Meanwhile, the pipe diameter of the loop and the temperature difference between the inlet and outlet of the high-temperature heat exchanger should be determined by considering both the performance of the FPSG and the power consumption of the pump.