bluuebunny/crossref_metadata_2025 huggingface dataset:
The Exergy Losses Analysis in Adiabatic Combustion Systems including the Exhaust Gas Exergy
Authors: Agrebi Senda , Dreßler Louis , Nishad Kaushal
Published: April 2022

The entropy generation analysis of adiabatic combustion systems was performed to quantify the exergy losses which are mainly the exergy destroyed during combustion inside the chamber and in the exhaust gases. The purpose of the present work was therefore: (a) to extend the exergy destruction analysis by including the exhaust gas exergy while applying the hybrid filtered Eulerian stochastic field (ESF) method coupled with the FGM chemistry tabulation strategy; (b) to introduce a novel method for evaluating the exergy content of exhaust gases; and (c) to highlight a link between exhaust gas exergy and combustion emissions. In this work, the adiabatic Sandia flames E and F were chosen as application combustion systems. First, the numerical results of the flow and scalar fields were validated by comparison with the experimental data. The under-utilization of eight stochastic fields (SFs), the flow field results and the associated scalar fields for the flame E show excellent agreement contrary to flame F. Then, the different exergy losses were calculated and analyzed. The heat transfer and chemical reaction are the main factors responsible for the exergy destruction during combustion. The chemical exergy of the exhaust gases shows a strong relation between the exergy losses and combustion emission as well as the gas exhaust temperature.
Parallel and Practical Approach of Efficient Image Chaotic Encryption Based on Message Passing Interface (MPI)
Authors: Abutaha Mohammed , Amar Islam , AlQahtani Salman
Published: April 2022

Encrypting pictures quickly and securely is required to secure image transmission over the internet and local networks. This may be accomplished by employing a chaotic scheme with ideal properties such as unpredictability and non-periodicity. However, practically every modern-day system is a real-time system, for which time is a critical aspect for achieving the availability of the encrypted picture at the proper moment. From there, we must improve encryption’s performance and efficiency. For these goals, we adopted the distributed parallel programming model, namely, the message passing interface (MPI), in this study. Using the message passing interface, we created a novel parallel crypto-system. The suggested approach outperforms other models by 1.5 times. The suggested parallel encryption technique is applicable.
Tales of Doctoral Students: Motivations and Expectations on the Route to the Unknown
Authors: Diogo Sara , Gonçalves Andreia , Cardoso Sónia , Carvalho Teresa
Published: April 2022

This paper provides a reflection on the way changes taking place in doctoral education are being perceived and internalized by doctoral students. The Doctoral perceptions are analyzed through Ph.D. candidates’ motivations to enroll in the program and to their levels of satisfaction with the supervision experience. Comparisons between national and international students, as well as differences according to doctoral programs’ scientific areas, i.e., between students enrolled in Science, Technology, Engineering and Mathematics (STEM) and in Social Sciences, Languages and Humanities (SSLH) are established. Based on a case study developed in a Portuguese university, conclusions point to the dominance of a romanticized, traditional view of doctoral education, with the academic profession at its core. This view is mostly shared by international students and those from SSLH scientific areas. In turn, national Ph.D. candidates and those from STEM areas have incorporated a more instrumental view of doctoral education, aiming for training participants to professions outside academia.
Engineering Student Experiences of Group Work
Authors: Rajabzadeh Amin Reza , Long Jennifer , Saini Guneet , Zeadin Melec
Published: April 2022

Soft skills are a crucial component for success in today’s workplace as employers increasingly value work that is collaborative and encompasses diverse perspectives. Despite this, most engineering programs fail to explicitly teach students transferable skills, including the best practices of group work. This research sought to explore how undergraduate experiences of group work change over time. This research also investigated what reflecting on cooperative education (co-op) experiences tells us about teaching group work in academic settings. Despite frequently noting the influence of group work in developing their communication skills and brainstorming ideas over time, students become somewhat more frustrated over time with their experiences of group work, mainly due to conflicting personalities and ideas among team members and/or a “slacker” student. However, our findings also show that students become more confident working in teams over time, as upper-year students were more likely to assume a leadership role and self-reported higher past performance as a group member. This study offers insights into the changing group work experiences of undergraduate engineering students as they progress through coursework and engage in experiential learning and work-integrated learning opportunities, such as co-op placements. The findings of this study can inform educators on how to best incorporate methods for teaching transferable soft skills.
In-Depth Evaluation of the Impact of National-Level DNS Filtering on DNS Resolvers over Space and Time
Authors: Cheng Yanan , Liu Yali , Li Chao , Zhang Zhaoxin , Li Ning , Du Yuejin
Published: April 2022

DNS filtering is the practice of blocking access to certain sites for a specific purpose, often content-based filtering. Unlike previous studies that focused on the behavior of national-level DNS filtering itself (e.g., location of filtering devices), we demonstrate and evaluate in depth the impact of DNS filtering on different types (public, ISP, and open) of DNS resolvers in the censored networks. In particular, we actively send DNS queries for 83 well-selected domain names to three types of DNS resolvers and keep track of the resolvers’ responses changing over time and space in China. Here, we present the results of our system running for 40 days, during which we obtained a total of 1.7 billion DNS records. Using these collected data, we found that specific DNS resolvers are unaffected by DNS filtering devices and can respond with the correct IP addresses for particular blocked domains. Furthermore, we revealed that three factors should be considered to evaluate the impact of a country-level DNS filtering mechanism: DNS resolver, client location, and blocked domain. Finally, we propose and implement a system to identify the correct IP addresses of blocked domain names in censored networks based on the characteristics of country-level DNS filtering.
The Development of 170 GHz, 1 MW Gyrotron for Fusion Application
Authors: Zhang Yichi , Zeng Xu , Bai Ming , Jin Ming , Hao Wenteng , Gao Dongshuo , Liu Qiao , Feng Jinjun
Published: April 2022

This paper presents the overall conceptual design of a 170 GHz, 1 MW gyrotron for plasma heating applications in thermonuclear fusion reactors. The operating mode is carefully selected with consideration of mode competition. The TE25,10 mode is determined as the operating mode in the present study. A weakly tapered conventional resonator is used for the study of the RF behavior, and multimode calculations are carried out for power and efficiencies. The optimized structure of the beam tunnel can further attenuate low-frequency oscillation. The design studies of a triode-type magnetic injection gun, quasi-optical mode converter, and single-disc sapphire window are also described. In addition, novel cold test methods which can effectively validate assembles are designed. In 2021, a prototype gyrotron was fabricated to validate the electronic–optic system and RF system. The current results obtained support an output power of 210 kW and efficiency of 15.9% through an initial low-power experiment. On the basis of the optimized design, an industrial prototype gyrotron is under fabrication as the heating source for the thermonuclear experimental reactor.
Advances in Sustainable Smart Cities and Territories
Authors: Corchado Juan M. , Trabelsi Saber
Published: April 2022

The smart city concept refers to the implementation of disruptive technologies in the urban environment, with the aim of creating an optimal citizen experience [...]
Comparative Study of Discrete PI and PR Controller Implemented in SRG for Wind Energy Application: Theory and Experimentation
Authors: Touati Zeineb , Pereira Manuel , Araújo Rui Esteves , Khedher Adel
Published: April 2022

The Switched Reluctance Generator (SRG) has been widely studied for Wind Energy Conversion Systems (WECS). However, a major drawback of the SRG system adopting the conventional control is the slow response of the DC link voltage controller. In this paper, a Proportional Resonant (PR) control strategy is proposed to control the output voltage of the SRG system to improve the fast response. The SRG model has a high non-linearity, which makes the design of controllers a difficult task. For this reason, the important practical engineering aspect of this work is the role played by the SRG model linearization in testing the sensitivity of the PR controller performance to specific parameter changes. The characteristics of steady-state behaviors of the SRG-based WECS under different control approaches are simulated and compared. The controller is implemented on a digital signal processor (TMS320F28379D). The experimental results are carried out using a 250 W 8/6 SRG prototype to assess the performance of the proposed control compared with the traditional Proportional Integral (PI) control strategy. The experimental results show that the PR control enhances the steady-state performance of the SR power generation system in WECS. Compared to PI control, the rise and settling times are reduced by 45% and 43%, respectively, without an overshoot.
Application of the Multiverse Optimization Method to Solve the Optimal Power Flow Problem in Alternating Current Networks
Authors: Rosales Muñoz Andrés Alfonso , Grisales-Noreña Luis Fernando , Montano Jhon , Montoya Oscar Danilo , Perea-Moreno Alberto-Jesus
Published: April 2022

In this paper, we solve the optimal power flow problem in alternating current networks to reduce power losses. For that purpose, we propose a master–slave methodology that combines the multiverse optimization algorithm (master stage) and the power flow method for alternating current networks based on successive approximation (slave stage). The master stage determines the level of active power to be injected by each distributed generator in the network, and the slave stage evaluates the impact of the proposed solution on each distributed generator in terms of the objective function and the constraints. For the simulations, we used the 10-, 33-, and 69-node radial test systems and the 10-node mesh test system with three levels of distributed generation penetration: 20%, 40%, and 60% of the power provided by the slack generator in a scenario without DGs. In order to validate the robustness and convergence of the proposed optimization algorithm, we compared it with four other optimization methods that have been reported in the specialized literature to solve the problem addressed here: Particle Swarm Optimization, the Continuous Genetic Algorithm, the Black Hole Optimization algorithm, and the Ant Lion Optimization algorithm. The results obtained demonstrate that the proposed master–slave methodology can find the best solution (in terms of power loss reduction, repeatability, and technical conditions) for networks of any size while offering excellent performance in terms of computation time.
Effect of Varying AgNO3 and CS(NH2)2 Concentrations on Performance of Ag2S/ZnO NRs/ITO Photoanode
Authors: Holi Araa , Zainal Zulkarnain , Al-Zahrani Asla , Ayal Asmaa , Najm Asmaa
Published: April 2022

This research focuses on improving the photoelectrochemical performance of binary heterostructure Ag2S/ZnO NRs/ITO by manipulating synthesis conditions, particularly the concentrations of sliver nitrate AgNO3 and thiourea CS(NH2)2. The photoelectrochemical performance of Ag2S/ZnO nanorods on indium tin oxide (ITO) nanocomposite was compared to pristine ZnO NRs/ITO photoanode. The hydrothermal technique, an eco-friendly, low-cost method, was used to successfully produce Ag2S/ZnO NRs at different concentrations of AgNO3 and CS(NH2)2. The obtained thin films were characterized using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis), and photoelectrochemical studies (PECs). We observed that there was an enhancement in absorbance in the visible region and effective photoelectron transfer between the Ag2S/ZnO NRs/ITO photoelectrode and the electrolyte Red-Ox when illuminated with 100 mW cm−2. Increasing the concentration of AgNO3 caused a remarkable decrease in the optical bandgap energy (Eg) values. However, we noticed that there was an unstable trend in Eg when the concentration of CS(NH2)2 was adjusted. The photoelectrochemical studies revealed that at a bias of 1.0 V, and 0.005 M of AgNO3 and 0.03 M of CS(NH2)2, the maximum photocurrent of the Ag2S/ZnO NRs/ITO photoanode was 3.97 mA/cm2, which is almost 11 times that of plain ZnO nanorods. Based on the outcomes of this investigating, the Ag2S/ZnO NRs/ITO photoanode is proposed as a viable alternative photoanode in photoelectrochemical applications.
Condensation Flow and Heat Transfer Characteristics of R410A in Micro-Fin Tubes and Three-Dimensional Surface Enhanced Tubes
Authors: Gao Yu , Cheng Hong , Li Wei , Kukulka David John , Smith Rick
Published: April 2022

Condensation heat transfer characteristics (using R410A as the working fluid) were studied experimentally to evaluate the heat transfer performance in copper and stainless-steel heat transfer tubes (smooth and enhanced). Experiments were carried out for a mass flux that varied from 250 to 450 kg m−2 s−1, at a saturation temperature of 318 K. Single-phase heat balance verification found that the heat loss is less than 6%, and the deviation between single-phase experimental results and various prediction correlations is less than 15%. Additionally, tube side condensation flow patterns were observed and recorded. Experimental results found that the enhancement ratio of the condensation heat transfer coefficient (enhanced tube/smooth tube) of the three-dimensional surface (1EHT) tube is in the range of 1.15~1.90, while the ratio of the micro-fin (HX) tube is in the range of 1.18~1.80. Heat transfer performance is affected by material conductivity, with the thermal conductivity of the smooth tube slightly affecting the heat transfer performance; larger heat transfer enhancements are produced in the enhanced tubes. At a low mass flow rates and vapor qualities, the flow pattern is a stratified wavy flow, while at higher mass flow rates and vapor qualities, the flow pattern is an annular flow (with the area in the enhanced tube being larger than the area of a smooth tube). Flow patterns in the smooth tube are consistent with the predicted values shown in previously reported flow pattern maps. A flow pattern diagram for condensation heat transfer in enhanced tubes is presented as part of this study. The condensation heat transfer coefficient increases with an increase in mass flow. When the mass flow rate increases, the turbulence of the liquid flow increases and the liquid film becomes thinner; thermal resistance is reduced and the heat transfer coefficient increases. Heat transfer values at lower mass velocities increase slightly with increasing mass flux values; however, at higher mass flux rates the heat transfer increase is larger than that at low mass flux values. Finally, tubes produced from high thermal conductivity materials produce larger heat transfer performance gains than the gains found in smooth tubes; small diameter tubes produce larger gains than larger diameter tubes.
Sieving and Covering of Wood Chips Improves Storability
Authors: Anerud Erik , Bergström Dan , Routa Johanna , Eliasson Lars
Published: April 2022

Minimising dry matter losses during storage of comminuted forest fuels is desirable from both an economic and a sustainability perspective. This study examined fuel quality and amount of recovered energy during the storage of forest wood chips stored at full industrial scale at three locations, and the effect of sieving and covering piles with a water-resistant, vapour-permeable fabric. Sieving wood chips before storage, that is, reducing the number of fines smaller than 8 mm, reduced the cumulative dry matter losses to <2%, while cumulative dry matter losses after storage for 4–6 months using current practices, that is, unsieved and uncovered, reached 10.6%. The combined effect of storage management led to a value loss of 11.5%, while both covering and sieving led to lower losses, with the combination of sieving and covering giving a 1.3% value increase, and thus, increased storability.
Recent Advances in Low-Carbon and Sustainable, Efficient Technology: Strategies and Applications
Authors: Chu Wenxiao , Vicidomini Maria , Calise Francesco , Duić Neven , Østergaard Poul Alborg , Wang Qiuwang , da Graça Carvalho Maria
Published: April 2022

The COVID-19 pandemic has had a significant impact on the supply chains of traditional fossil fuels. According to a report by the International Energy Agency (IEA) from 2020, oil-refining activity fell by more than the IEA had anticipated. It was also assumed that the demand in 2021 would likely be 2.6 million bpd below the 2019 levels. However, renewable markets have shown strong resilience during the crisis. It was determined that renewables are on track to meet 80% of the growth in electricity demand over the next 10 years and that sustainable energy will act as the primary source of electricity production instead of coal. On the other hand, the report also emphasized that measures for reducing environmental pollution and CO2 emissions are still insufficient and that significant current investments should be further expanded. The Sustainable Development of Energy, Water and Environment Systems (SDEWES) conference series is dedicated to the advancement and dissemination of knowledge on methods, policies and technologies for improving the sustainability of development by decoupling growth from the use of natural resources. The 15th SDEWES conference was held online from 1–5 September 2020; more than 300 reports with 7 special sections were organized on the virtual conference platform. This paper presents the major achievements of the recommended papers in the Special Issue of Energies. Additionally, related studies connected to the above papers published in the SDEWES series are also introduced, including the four main research fields of energy saving and emission reduction, renewable energy applications, the development of district heating systems, and the economic assessment of sustainable energy.
Analysis and Operation of a High DC-AC Gain 3-ϕ Capacitor Clamped Boost Inverter
Authors: Raveendhra Dogga , Rajana Poojitha , Narasimharaju Beeramangalla Lakshminarasaiah , Babu Yaramasu Suri , Rusu Eugen , Fayek Hady Habib
Published: April 2022

This article introduces a three-phase capacitor clamped inverter with inherent boost capability by relocating the filter components from the AC side to the configuration’s midpoint. This topology has several distinguishing characteristics, including: (a) low component count; (b) high DC-AC gain; (c) decreased capacitor voltage stresses; (d) improved power quality (extremely low voltage and current THDs) without the use of an AC-side filter; and (e) decreased voltage stresses on power semiconductor devices. Simulations were carried out on the MATLAB Simulink platform, and results under steady-state conditions, load and reference change conditions, and phase sequence change conditions, along with THD profiles, are presented. This inverter’s performance was compared to that of similar converters with intrinsic gain. A 1200 W experimental prototype was built to demonstrate the system’s feasibility and benefits. When compared to existing topologies, simulation and experimental results indicate that the proposed inverter provides superior high gain, smooth control, low stress, and a long life time.
Bioeconomy for Resilient Post-COVID Economies
Authors: Rozakis Stelios , Juvančič Luka , Kovacs Barna
Published: April 2022

In the creation of this Special Issue, the editors identified circular bioeconomy, i [...]
Petrology, Physical Properties and Geochemical Characteristics of Alkaline Lake Shale—Fengcheng Formation in Mahu Sag, Junggar Basin
Authors: Zhao Kang , Zhang Changmin , Zhang Lei , An Zhiyuan , Xu Qinghai , Zhou Xinrui
Published: April 2022

There are rare comparative studies on the geological characteristics of shale in different members of Permian Fengcheng Formation in Mahu Sag, Junggar basin, China. In order to compare the mineral composition, physical properties, and geochemical characteristics of shale in three members of Fengcheng Formation in Mahu Sag, a large number of test data such as X-ray diffraction, high-pressure mercury injection, organic carbon, rock pyrolysis, and vitrinite reflectance were collected and analyzed. Results showed that the content of clay minerals in the shale of the third member of Fengcheng Formation (P1f3) is the highest. The content of carbonate minerals is the highest and the content of clay minerals is the lowest in the shale of the second member of Fengcheng Formation (P1f2). The content of felsic minerals is the highest and the content of carbonate minerals is the lowest in the shale of the first member of Fengcheng Formation (P1f1). The physical properties of the shale of P1f3 are the best, and the porosity of the shale of P1f2 is the smallest, but its permeability is relatively large, and the permeability of shale of P1f1 is the lowest. The organic matter abundance of shale of P1f2 is the highest, while that of P1f1 is relatively the lowest. Most of the organic matter types of shale of P1f3 are type I–II, those of P1f2 are mainly type II, and those of P1f1 section are distributed from type I–III. On the whole, the shale of Fengcheng Formation in the peripheral fault zone and slope area of Mahu Sag has reached the low mature to mature stage, and the shale in the central area of the sag has reached the mature stage. More than half of the shale samples of Fengcheng Formation belong to fair to good source rocks, especially the samples of P1f2. A few samples from P1f3 and P1f1 belong to non-source rocks. This study indicates that the shale of Fengcheng Formation in Mahu Sag has good hydrocarbon generation potential, especially the shale of P1f2, and can become the target of shale oil exploration.
Energy System Development Scenarios: Case of Poland
Authors: Wisniewski Radoslaw , Daniluk Piotr , Kownacki Tomasz , Nowakowska-Krystman Aneta
Published: April 2022

Europe’s ambition to be the first climate-neutral continent and to achieve net-zero greenhouse gas emissions by 2050 will result in changes to the energy systems of many countries. This overlaps with the principles of circular economy, energy independence, and the continuity of operations enshrined in many national and regional documents. From the above, a scenario based on renewable resources emerges. However, in a country such as Poland, with conventional energy sources and large state participation in the sector, is this feasible? The authors assumed that the urgent need for a turbulence-sensitive analysis of energy sector changes can be met by using a new view, defined by the authors as a matrix of four oceans scenarios. Black, Grey, Red and Green scenarios are determined by the proportion of the state and the local-community sector. Then, assuming the possibility of introducing two of them by 2050—Green (radical) and Red (competitive)—empirical research was carried out on a purposively selected group of experts. The business model of the sector was analyzed in terms of six links that create economic and social value: energy sources, energy producers, transmission networks with infrastructure, energy storage, energy system management and energy consumers. According to experts, development of business model links will be based on the Red scenario. Thus, we get a picture of a model that should be considered by politicians, scientists, as well as a wide audience that absorbs the effects of environmental pollution.
Efficiency Analytical Characterization for Brushless Electric Drives
Authors: Brando Gianluca , Dannier Adolfo , Del Pizzo Andrea
Published: April 2022

The paper is focused on the formalization of an experimental procedure aimed to characterize the efficiency behaviour of a Permanent Magnet Synchronous Motor-based drive. The characterization is intended to expose the analytical behaviour of the system efficiency by the actual operating condition assigned through torque/speed value. The availability of such a relation in a simple analytical form would allow for real-time adjustment by advanced power management strategies to maximize the whole system efficiency. The proposed method is based on a defined set of measures corresponding to several drive operating conditions. A straightforward elaboration procedure is then formulated with the aim to quantify the different parameters, which intervene in the efficiency characterization. The method has been applied on a 155 kW drive. The results show that good accuracy is achieved while keeping the analytical approach relatively simple.
Oscillation of Cavitating Vortices in Draft Tubes of a Simplified Model Turbine and a Model Pump–Turbine
Authors: Skripkin Sergey , Zuo Zhigang , Tsoy Mikhail , Kuibin Pavel , Liu Shuhong
Published: April 2022

The self-oscillation of the cavitating vortices is one of the dangerous phenomena of hydraulic turbine operation near full-load conditions. This work is an attempt to generalize data and expand insight on the phenomenon of self-excited oscillations by comparing the experimental results obtained on a simplified turbine and scaled-down pump–turbine models. In both cases, a series of high-speed imaging was carried out, which made it possible to study these phenomena with high temporal resolution. The high-speed imaging data was subjected to additional processing such as binarization, cropping, and scaling. For a simplified turbine model, the volume of the vapor cavity was calculated based on the assumption of the axial symmetry of the cavity, after which fast Fourier transform (FFT) analysis was carried out. A proper orthogonal decomposition (POD) analysis was also performed to examine individual modes in the original digital imaging data. For the pump–turbine, visualization data on the cavitation cavity oscillations were supplemented by pressure measurements in the draft tube cone to determine the frequency characteristics. Based on obtained experimental data, an improved one-dimensional model describing the oscillations of the cavitation cavity arising behind the hydraulic turbine runner is proposed.
An Accurate Switching Transient Analytical Model for GaN HEMT under the Influence of Nonlinear Parameters
Authors: Yan Dong , Hang Lijun , He Yuanbin , He Zhen , Zeng Pingliang
Published: April 2022

The Gallium Nitride high electron mobility transistor (GaN HEMT) has been considered as a potential power semiconductor device for high switching speed and high power density application since its commercialization. Compared with the traditional Si transistors, GaN HEMT has faster switching speed and lower on-off loss. As a result, it is more sensitive to the nonlinear parameters due to the fast switching speed. The subsequent voltage and current overshooting will affect the efficiency and safety of the GaN HEMT and power electronic systems. In this paper, an accurate switching transient analytical model for GaN HEMT is proposed, which considers the effects of parasitic inductances, nonlinear junction capacitances and nonlinear transconductance. The model characteristic of turn-ON process and turn-OFF process is illustrated in detail, and the equivalent circuits are derived for each switching transition. The accuracy of the proposed model can be verified by comparing the predicted switching waveform and switching loss with that of the experimental results based on the double pulse test (DPT) circuit. Compared with the conventional model, the proposed model is more accurate and matches better with the experimental results than the conventional model. Finally, this model can be used for analyzing the influences of gate resistance, nonlinear junction capacitances, and parasitic inductances on switching transient waveform and refining calculation switching loss.
A Compendium of Formulae for Natural Frequencies of Offshore Wind Turbine Structures
Authors: Varghese Ramon , Pakrashi Vikram , Bhattacharya Subhamoy
Published: April 2022

The design of an offshore wind turbine system varies with the turbine capacity, water depth, and environmental loads. The natural frequency of the structure, considering foundation flexibility, forms an important factor in structural design, lifetime performance estimates, and cost estimates. Although nonlinear numerical analysis in the time domain is widely used in the offshore industry for detailed design, it becomes necessary for project planners to estimate the natural frequency at an earlier stage and rapidly within reasonable accuracy. This paper presents a compendium of mathematical expressions to compute the natural frequencies of offshore wind turbine (OWT) structures on various foundation types by assimilating analytical solutions for each type of OWT, obtained by a range of authors over the past decade. The calculations presented can be easily made using spreadsheets. Example calculations are also presented where the compiled solutions are compared against publicly available sources.
Distributed Secondary Control in Microgrids Using Synchronous Condenser for Voltage and Frequency Support
Authors: Nguyen Tung , Nguyen Ha , Wang Yu , Mohammed Osama , Anagnostou Emmanouil
Published: April 2022

A high share of distributed energy resources (DERs) in power distribution grids has posed many challenges for system operation and control. Microgrid (MG) application with different distributed control approaches for DERs has been drawn a lot of attention from the research community to provide more flexibility, reliability and resilience for the system. This paper develops a distributed secondary control for DERs in MGs and on top of that using synchronous condenser (SC) participating in the secondary control for voltage support. The proposed distributed secondary control framework of MGs is designed to obtain four objectives as follows: (i) frequency restoration, (ii) average voltage restoration, (iii) arbitrary active power sharing among SGs and BESSs and (iv) arbitrary reactive power sharing among all SGs, BESSs and SCs. The comparison results under different scenarios show that with SC participating in the distributed secondary control in MGs, the system frequency and voltage response are much improved and quickly recovered to the nominal values thanks to the natural inertia response and fast reactive power control of SC sharing with other DERs in the MGs. Additionally, a multi-agent system is implemented to realize the proposed control method in hardware environment.
Application of Doubly Connected Dominating Sets to Safe Rectangular Smart Grids
Authors: Cyman Joanna , Raczek Joanna
Published: April 2022

Smart grids, together with the Internet of Things, are considered to be the future of the electric energy world. This is possible through a two-way communication between nodes of the grids and computer processing. It is necessary that the communication is easy and safe, and the distance between a point of demand and supply is short, to reduce the electricity loss. All these requirements should be met at the lowest possible cost. In this paper, we study a two-dimensional rectangular grid graph which is considered to be a model of a smart grid; nodes of the graph represent points and devices of the smart grid, while links represent possible ways of communication and energy transfer. We consider the problem of choosing the lowest possible number of locations (nodes, points) of the grid which could serve as energy sources (or a source of different resources) to other nodes in such a way that we ensure reduction in electricity loss and provide safe communication and resistance to failures and increases in energy demand.Therefore, we study minimum doubly connected dominating sets in grid graphs. We show that the proposed solutions are the best possible in terms of the number of source points for the case of narrow grid graphs and we give upper and lower bounds for the case of wide grid graphs.
What Is Worth Knowing in Interventional Practices about Medical Staff Radiation Exposure Monitoring: A Review of Recent Outcomes of EURADOS Working Group 12
Authors: Ferrari Paolo , Ginjaume Mercè , Hupe Oliver , O’Connor Una , Vanhavere Filip , Bakhanova Elena , Becker Frank , Campani Lorenzo , Carinou Eleftheria , Clairand Isabelle , Faj Dario , Jansen Jan , Jovanović Zoran , Knežević Željka , Krstić Dragana , Mariotti Francesca , Sans-Merce Marta , Teles Pedro , Živković Milena
Published: April 2022

EURADOS (European Radiation Dosimetry Group) Working Group 12 (WG12) SG1 activities are aimed at occupational radiation protection and individual monitoring in X-ray and nuclear medicine practices. In recent years, many studies have been carried out in these fields, especially for interventional radiology and cardiology workplaces (IC/IR). The complexity of the exposure conditions of the medical staff during interventional practices makes the radiation protection and monitoring of the exposed workers a challenging task. The scope of the present work is to review some of the main results obtained within WG12 activities about scattered field characterization and personal dosimetry that could be very useful in increasing the quality of radiation protection of the personnel, safety, and awareness of radiation risk. Two papers on Monte Carlo modelling of interventional theater and three papers on active personal dosimeters (APDs) for personnel monitoring were considered in the review. More specifically, Monte Carlo simulation was used as the main tool to characterize the levels of exposure of the medical staff, allowing to determine how beam energy and direction can have an impact on the doses received by the operators. Indeed, the simulations provided information about the exposure of the operator’s head, and the study concluded with the determination of an eye-lens protection factor when protection goggles and a ceiling shielding are used. Moreover, the review included the results of studies on active personal dosimeters, their use in IC/IR workplaces, and how they respond to calibration fields, with X-ray standard and pulsed beams. It was shown that APDs are insensitive to backscatter radiation, but some of them could not respond correctly to the very intense pulsed fields (as those next to the patient in interventional practices). The measurements during interventional procedures showed the potential capability of the employment of APDs in hospitals.
Fiber-Reinforced Polymer Composites in the Construction of Bridges: Opportunities, Problems and Challenges
Authors: Kossakowski Paweł Grzegorz , Wciślik Wiktor
Published: April 2022

In this review, we discuss the basic issues related to the use of FRP (fiber-reinforced polymer) composites in bridge construction. This modern material is presented in detail in terms of the possibility of application in engineering structures. A general historical outline of the use and development of modern structural materials, such as steel and concrete, is included to introduce composites as a novel material in engineering, and the most important features and advantages of polymers as a construction material are characterized. We also compare FRP to basic structural materials, such as steel and concrete, which enables estimation of the effectiveness of using of FRP polymers as structural material in different applications. The first bridges made of FRP composites are presented and analyzed in terms of applied technological solutions. Examples of structural solutions for deck slabs, girders and other deck elements made of FRP composites are discussed. Particular attention is paid to the systems of deck slabs, especially those composed of pultruded profiles, sandwich panels and hybrid decks. The disadvantages of composites, as well as barriers and limitations in their application in engineering practice, are presented. Exemplary analyses of the costs of construction, maintenance and demolition of FRP composite bridges are presented and compared with the corresponding costs of concrete and steel bridges. The directions of development of composite bridge structures and the greatest challenges facing engineers and constructors in the coming years are discussed.
Descriptions of Two New Species, Sillago muktijoddhai sp. nov. and Sillago mengjialensis sp. nov. (Perciformes: Sillaginidae) from the Bay of Bengal, Bangladesh
Authors: Saha Shilpi , Song Na , Yu Zhengsen , Baki Mohammad Abdul , McKay Roland J. , Qin Jianguang , Gao Tianxiang
Published: April 2022

Due to difficulty in recognition, many true species have been covered under the synonyms of wide-spread species. To justify the identification of a widely distributed species, Sillago sihama from the Bay of Bengal, Bangladesh, an integrated approach including morphology and DNA barcoding was used. Two unrecognized species of Sillago, i.e., Sillagomuktijoddhai sp. nov. and S. mengjialensis sp. nov., were identified from the coastal area of Bangladesh. S. muktijoddhai sp. nov. has marked differences in the body color, anal fin color, number of gill rakers, snout length, and swimbladder. S. mengjialensis sp. nov. has notable differences in the anal fin color, snout length, and swimbladder and is distinguished from S. muktijoddhai sp. nov. by the body color and swimbladder. The morphological characters of 14 documented Sillago species with two posterior extensions of the swimbladder were referenced and distinguished to accredit the two new species. Genetic analyses of partial mitochondrial cytochrome oxidase subunit I and 16S ribosomal RNA also supported the validity of the new species. This study has increased the number of recognized species of Sillago in the world and confirmed the prevailing misidentification of these two new species in Bangladesh as so-called S. sihama. Moreover, the study confirmed the misidentification of S. mengjialensis sp. nov. in Indonesia as S. sihama and the identification of unknown Sillago sp.1 in India.
Bacillus subtilis Supplementation in a High-Fat Diet Modulates the Gut Microbiota and Ameliorates Hepatic Lipid Accumulation in Grass Carp (Ctenopharyngodon idella)
Authors: Guo Daoyuan , Xie Mengqi , Xiao Hang , Xu Lili , Zhang Shiyu , Chen Xiaoxuan , Wu Zhixin
Published: April 2022

To study the effects of Bacillus subtilis supplementation in a high-fat diet on the gut microbiota and nonalcoholic fatty liver disease in grass carp (Ctenopharyngodon idella), juveniles (60 ± 5 g) were fed three diets: (a) a control diet (CON), (b) a high-fat diet (HFD) and (c) a high-fat diet supplemented with B. subtilis (HFD + BS). After 8 weeks of feeding, fish growth, serum biochemical indices and total liver lipid content were measured, and gut microbiota analysis was performed using the MiSeq250 high-throughput sequencing platform. The results of this study showed that B. subtilis could improve growth and blood serum indices and reduce lipid deposition in the fish liver, preventing fatty liver disease. A grass carp model of fatty liver induced by a high-fat diet was successfully established. Moreover, B. subtilis altered the intestinal microbiota of HFD-fed grass carp, making it more similar to that of the control group. This study revealed the important effects of B. subtilis on grass carp with fatty liver induced by a high-fat diet and provides the foundation for the application of probiotics in grass carp farming.
Interactions between Ascophyllum nodosum Seaweeds Polyphenols and Native and Gelled Corn Starches
Authors: Gisbert Mauro , Aleixandre Andrea , Sineiro Jorge , Rosell Cristina M. , Moreira Ramón
Published: April 2022

The effect of several blending procedures between Ascophyllum nodosum seaweed flour (AF) and corn starch (CS) on the interactions between polyphenols and starch was studied in this paper. These methods comprised the blending of AF with native starch (NT) with previously gelled starch gel (GL) and promoting the gelling of corn starch in the presence of AF (CGL). Different AF–CS (g/g) ratios (from 1:0.5 to 1:25) were studied. The liquid phase was chemically characterized by polyphenols (TPC) and carbohydrates content. The antioxidant activity of the liquid phase after achieving the solid–liquid equilibrium was determined by DPPH, ABTS, and FRAP methods. The solid phase was characterized by FT-IR and SEM techniques. The Halsey model successfully fitted the equilibrium TPC in liquid and polyphenols adsorbed/retained by the solid phase of tested systems. NT samples showed lower polyphenols sorption than gelled samples. The differences found between samples obtained with GL and CGL methods suggested different interactions between polyphenols and starch. Specifically, physisorption is predominant in the case of the GL method, and molecular trapping of polyphenols in the starch gel structure is relevant for the CGL method. Results allowed us to determine the enhancement of the retention of polyphenols to achieve starchy foods with high bioactivity.
Phytochemicals, Pharmacological Effects and Molecular Mechanisms of Mulberry
Authors: Hao Junyu , Gao Yufang , Xue Jiabao , Yang Yunyun , Yin Jinjin , Wu Tao , Zhang Min
Published: April 2022

There are numerous varieties of mulberry, and each has high medicinal value and is regarded as a promising source of traditional medicines and functional foods. Nevertheless, the nutrients and uses of mulberry differ from species (Morus alba L., Morus nigra L. and Morus rubra L.). Phenolic compounds are prominent among the biologically active ingredients in mulberry, especially flavonoids, anthocyanins and phenolic acids. Epidemiologic studies suggest that mulberry contains a rich, effective chemical composition and a wide range of biological activity, such as antioxidant, anti-inflammatory, anti-tumor and so on. However, compared with other berries, there has been a lack of systematic research on mulberry, and this hinders its further expansion as a functional fruit. The main purpose of this review is to provide the latest data regarding the effective chemical constituents and pharmacological effects of mulberry to support its further therapeutic potential and health functions.
Application of Two-Dimensional Fluorescence Spectroscopy for the On-Line Monitoring of Teff-Based Substrate Fermentation Inoculated with Certain Probiotic Bacteria
Authors: Alemneh Sendeku Takele , Emire Shimelis Admassu , Jekle Mario , Paquet-Durand Olivier , von Wrochem Almut , Hitzmann Bernd
Published: April 2022

There is increasing demand for cereal-based probiotic fermented beverages as an alternative to dairy-based products due to their limitations. However, analyzing and monitoring the fermentation process is usually time consuming, costly, and labor intensive. This research therefore aims to apply two-dimensional (2D)-fluorescence spectroscopy coupled with partial least-squares regression (PLSR) and artificial neural networks (ANN) for the on-line quantitative analysis of cell growth and concentrations of lactic acid and glucose during the fermentation of a teff-based substrate. This substrate was inoculated with mixed strains of Lactiplantibacillus plantarum A6 (LPA6) and Lacticaseibacillus rhamnosus GG (LCGG). The fermentation was performed under two different conditions: condition 1 (7 g/100 mL substrate inoculated with 6 log cfu/mL) and condition 2 (4 g/100 mL substrate inoculated with 6 log cfu/mL). For the prediction of LPA6 and LCGG cell growth, the relative root mean square error of prediction (pRMSEP) was measured between 2.5 and 4.5%. The highest pRMSEP (4.5%) was observed for the prediction of LPA6 cell growth under condition 2 using ANN, but the lowest pRMSEP (2.5%) was observed for the prediction of LCGG cell growth under condition 1 with ANN. A slightly more accurate prediction was found with ANN under condition 1. However, under condition 2, a superior prediction was observed with PLSR as compared to ANN. Moreover, for the prediction of lactic acid concentration, the observed values of pRMSEP were 7.6 and 7.7% using PLSR and ANN, respectively. The highest error rates of 13 and 14% were observed for the prediction of glucose concentration using PLSR and ANN, respectively. Most of the predicted values had a coefficient of determination (R2) of more than 0.85. In conclusion, a 2D-fluorescence spectroscopy combined with PLSR and ANN can be used to accurately monitor LPA6 and LCGG cell counts and lactic acid concentration in the fermentation process of a teff-based substrate. The prediction of glucose concentration, however, showed a rather high error rate.
Metabolomic Analysis, Combined with Enzymatic and Transcriptome Assays, to Reveal the Browning Resistance Mechanism of Fresh-Cut Eggplant
Authors: Liu Xiaohui , Xiao Kai , Zhang Aidong , Zhu Weimin , Zhang Hui , Tan Feng , Huang Qianru , Wu Xuexia , Zha Dingshi
Published: April 2022

Browning has been the primary limitation in eggplant processing. This study investigates the molecular mechanism underlying fresh-cut eggplant fruit browning by observing the physicochemical characteristics of browning-resistant (‘F’) and browning-sensitive (‘36′) eggplant cultivars. Browning-related enzyme activity and gene expression (PPO, LOX, and PLD) were significantly higher in the ‘36′ eggplant, thereby enhancing the degree of browning, compared to the ‘F’ eggplant. The MDA content and O2− production rate progressively increased as browning increased, while the antioxidant capacity of the fruit decreased. The cutting injury significantly activated the expression of PAL, thereby inducing the accumulation of phenolic acids, while the PPO gene was significantly upregulated, which activated the activity of polyphenol oxidase. Our results showed that the oxidation of chlorogenic acids to chlorogenic quinones resulted in the occurrence of browning, which suggests chlorogenic acid as the main browning substrate in fresh-cut eggplant.
Expression Characteristics in Roots, Phloem, Leaves, Flowers and Fruits of Apple circRNA
Authors: Wang Dajiang , Gao Yuan , Sun Simiao , Li Lianwen , Wang Kun
Published: April 2022

Circular RNAs (circRNAs) are covalently closed non-coding RNAs that play pivotal roles in various biological processes. However, circRNAs’ roles in different tissues of apple are currently unknown. A total of 6495 unique circRNAs were identified from roots, phloem, leaves, flowers and fruits; 65.99% of them were intergenic circRNAs. Similar to other plants, tissue-specific expression was also observed for apple circRNAs; only 175 (2.69%) circRNAs were prevalently expressed in all five different tissues, while 1256, 1064, 912, 904 and 1080 circRNAs were expressed only in roots, phloem, leaves, flowers and fruit, respectively. The hosting-genes of circRNAs showed significant differences enriched in COG, GO terms or KEGG pathways in five tissues, suggesting the special functions of circRNAs in different tissues. Potential binding interactions between circRNAs and miRNAs were investigated using TargetFinder; 2989 interactions between 647 circRNAs and 192 miRNA were predicated in the present study. It also predicted that Chr00:18744403|18744580-mdm-miR160 might play an important role in the formation of flowers or in regulating the coloration of flowers, Chr10:6857496|6858910–mdm-miR168 might be involved in response to drought stress in roots, and Chr03:1226434|1277176 may absorb mdm-miR482a-3p and play a major role in disease resistance. Two circRNAs were experimentally analyzed by qRT-PCR with divergent primers, the expression levels were consistent with RNA-seq, which indicates that the RNA-seq datasets were reliable.