bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Multi-Strategy Routing Protocol in Flying Ad Hoc Networks
Authors: Xin Ning , Chen Xiaoqun , Chen Te , Liu Feng , Liu Kun , Lin Yuxiong
Published: October 2022

In this paper, a multi-strategy routing protocol, reactive-greedy-face (RGF), is proposed based on the advantages of reactive forwarding, greedy forwarding, and projected face forwarding strategies. This protocol improves and unites the strategies through a reasonable selection and switching mechanism to make up for the deficiencies of the existing three-dimensional routing protocols in the flight self-assembly network and improve the rapid recovery of packet forwarding after topology changes. The simulation validation shows that this routing protocol can be used to recover packets after a topology change. Simulation verification indicates that the routing protocol significantly improves the packet delivery rate and the average end-to-end delay performance, and can better adapt to the flight self-assembly network’s three-dimensional high-dynamic and low-density characteristics.
A Generative Learning Steganalysis Network against the Problem of Training-Images-Shortage
Authors: Zhang Han , Song Zhihua , Xing Qinghua , Feng Boyu , Lin Xiangyang
Published: October 2022

In recent years, several steganalysis neural networks have been proposed and achieved satisfactory performances. However, these deep learning methods all encounter the problem of Training-Images-Shortage (TIS). In most cases, it is difficult for steganalyses to obtain enough signals about steganography from a game opponent. In order to solve the problem of TIS for steganalysis, we propose a novel steganalysis method based on generative learning and deep residual convolutional neural networks. Comparative experiments show that the proposed architecture can achieve promising performance in response to spatial domain steganalysis despite a lack of training images.
Sequential Transient Detection for RF Fingerprinting
Authors: Taşcıoğlu Selçuk , Köse Memduh , Soysal Gökhan
Published: October 2022

In this paper, a sequential transient detection method for radio frequency (RF) fingerprinting used in the identification of wireless devices is proposed. To the best knowledge of the authors, sequential detection of transient signals for RF fingerprinting has not been considered in the literature. The proposed method is based on an approximate implementation of the generalized likelihood ratio algorithm. The method can be implemented online in a recursive manner with low computational and memory requirements. The transients of wireless transmitters are detected by using the likelihood ratio of the observations without the requirement of any a priori knowledge about the transmitted signals. The performance of the method was evaluated using experimental data collected from 16 Wi-Fi transmitters and compared to those of two existing methods. The experimental test results showed that the proposed method can be used to detect the transient signals with a low detection delay. Our proposed method estimates transient starting points 20-times faster compared to an existing robust method, as well as providing a classification performance of a mean accuracy close to 95%.
The Efficient Design of Lossy P-LDPC Codes over AWGN Channels
Authors: Wang Runfeng , Liu Sanya , Wu Huihui , Wang Lin
Published: October 2022

Considering the high compression requirements of transmission, lossy block codes are particularly concerned due to their good compression performance and simple implementation. This paper investigates and analyzes the distortion rate performance of protograph LDPC (P-LDPC) codes for Bernoulli sources over AWGN channels. We first analytically establish the connection between the parity check matrix of a P-LDPC code and the extra distortion caused by the noisy channels. It was found that the additional distortion related to channel noise increases with the rising total degree of a parity check matrix. Further, two design algorithms are proposed for optimizing lossy multirate P-LDPC codes, considering the effect of noisy channels. Finally, simulation results demonstrate the robustness of the optimized P-LDPC codes over noisy channels.
Synthesis, Structure Characterization and Study of a New Kind of Catalyst: A Monolith of Nickel Made by Additive Manufacturing Coated with Platinum
Authors: Hasan Ahmad O. , Essa Khamis , Gomaa Mohamed R.
Published: October 2022

The monitoring of environmental contamination is an important issue to protect human health and the atmospheric environment. In this study, the optical imaging of mesh structures not coated and coated with platinum was performed to analyze the optical characteristics of the lattices. A nickel monolith catalyst was manufactured via additive manufacturing and coated with platinum, and it was presented to characterize the catalyst properties. The analysis focused on the process of coating using hydrazine bath as a reducing agent. The results showed an increase in the thickness of the coating with baths with durations of 1.5 h, 2.0 h and 2.5 h. The coating thickness was strongly dependent on time duration. The SEM images and EDX were used to confirm the process of coating and analyze the presence of platinum on the catalyst. Coating layers were very thin, and others were not homogeneous over the surface. When the catalyst was exposed to platinum for 2.5 h, the catalyst showed an efficiency of 0.06% for NOx, 0.10%, for CO and 0.09% for HC reduction.
Peculiarities of Housing and Communal Services and the Difficulties of Implementing Energy-Saving Technologies: The Case of Kazakhstan
Authors: Shevyakova Anna , Petrenko Yelena , Koshebayeva Gaukhar , Ulybyshev Dmitry
Published: October 2022

The article considers the problems arising in the implementation of energy-saving technologies in the housing and communal services sector of Kazakhstan, including the example of specific situations. Despite the global trend of energy saving and increasing the energy efficiency of production and service provision, there is almost no introduction of energy-saving technologies by utility companies in Kazakhstan. After reviewing the experience of the previous 10 years and the unsuccessful attempts of Western manufacturers to enter this market, we identified the reasons for this situation, namely, the need to identify the exact institutional need for implementation with reference to the Kazakhstan regulatory framework, the need to consider the financial effect of the projects, not according to the prices of the producing countries (which are usually Western countries, where utility bills are much higher) but the Kazakhstan energy prices and/or tariffs for the necessary resources, as well as the necessity to calculate the economic and/or social effectiveness of the project. The authors present the results of the analysis of public utilities of Kazakhstan as DMUs (decision-making units). Data envelopment analysis (DEA) was chosen as the method of analysis, which allows for a nonparametric evaluation of economic agents by several input and output parameters. The authors also propose aspects of technical policy aimed at the development of energy conservation in Kazakhstan.
Effect of Nonlinear Spring Characteristics on the Efficiency of Free-Piston Engine Generator
Authors: Irie Shoma , Sato Mitsuhide , Mizuno Tsutomu , Nishimura Fumiya , Naganuma Kaname
Published: October 2022

Piston motion is an important factor in improving the energy conversion efficiency of free-piston engine generators (FPEGs), and an air cylinder is an important component affecting piston motion. In this study, the effect of the air cylinder specifications on the piston drive frequency and energy conversion efficiency is clarified. By considering that the repulsion force of an air cylinder is nonlinear, the main factors that change the piston drive frequency were investigated by simulation. In addition, a piston drive frequency diagram was drawn based on the top surface area of the air cylinder and the compression ratio to discuss the effect of the air cylinder specifications on the piston drive frequency. The results indicate that the air cylinder specifications affect the piston drive frequency and generation force of a linear machine. Moreover, the structure of the air cylinder and the constraints on the maximum generation force of the linear machine narrow the possible operating range in the piston drive frequency. The air cylinder specifications based on the piston drive frequency diagram improved the FPEG energy conversion efficiency by 0.5%.
A Review of Laboratory and Numerical Techniques to Simulate Turbulent Flows
Authors: Ferrari Simone , Rossi Riccardo , Di Bernardino Annalisa
Published: October 2022

Turbulence is still an unsolved issue with enormous implications in several fields, from the turbulent wakes on moving objects to the accumulation of heat in the built environment or the optimization of the performances of heat exchangers or mixers. This review deals with the techniques and trends in turbulent flow simulations, which can be achieved through both laboratory and numerical modeling. As a matter of fact, even if the term “experiment” is commonly employed for laboratory techniques and the term “simulation” for numerical techniques, both the laboratory and numerical techniques try to simulate the real-world turbulent flows performing experiments under controlled conditions. The main target of this paper is to provide an overview of laboratory and numerical techniques to investigate turbulent flows, useful for the research and technical community also involved in the energy field (often non-specialist of turbulent flow investigations), highlighting the advantages and disadvantages of the main techniques, as well as their main fields of application, and also to highlight the trends of the above mentioned methodologies via bibliometric analysis. In this way, the reader can select the proper technique for the specific case of interest and use the quoted bibliography as a more detailed guide. As a consequence of this target, a limitation of this review is that the deepening of the single techniques is not provided. Moreover, even though the experimental and numerical techniques presented in this review are virtually applicable to any type of turbulent flow, given their variety in the very broad field of energy research, the examples presented and discussed in this work will be limited to single-phase subsonic flows of Newtonian fluids. The main result from the bibliometric analysis shows that, as of 2021, a 3:1 ratio of numerical simulations over laboratory experiments emerges from the analysis, which clearly shows a projected dominant trend of the former technique in the field of turbulence. Nonetheless, the main result from the discussion of advantages and disadvantages of both the techniques confirms that each of them has peculiar strengths and weaknesses and that both approaches are still indispensable, with different but complementary purposes.
Energy Productivity of Microinverter Photovoltaic Microinstallation: Comparison of Simulation and Measured Results—Poland Case Study
Authors: Olczak Piotr
Published: October 2022

From 2010 in Europe and from 2019 in Poland, the development of a significant number of photovoltaic (PV) microinstallations have been observed; for example, 1 million PV installations were built in Poland, September 2019–May 2022. A PV microinstallation is typically designed for a household (single-family house). Their capacity and energy productivity should be aligned with energy consumption in a given period, for example, a year (prosumer rules in Poland). The aim of this study is to verify the possibilities and accuracy of the use of PV energy production calculation methods in Polish conditions. The existing methods of calculating the energy produced may be inaccurate due to non-adaptation to terrain conditions, place, wind conditions, representativeness of PV panels in the installation, and many other factors. In the study, the HDKR (Hay, Davies, Klucher, Reindl) method was used based on data from the 0.25-degree (both longitude and latitude) mesh of ERA5 weather conditions. Then, the theoretical energy productivity from PV panels was calculated based on broadly used methods like those used in HOMER software. Statistical verification was done to compare the obtained energy production results from 10 PV panels with real results from microinstallations (energy productivity from each panel measured). The representativeness of the analysis period (one year) over the years was also checked using statistical methods. This is the first study to evaluate energy production from a microinverter installation in real conditions in Central Eastern Europe.
Analysis of Roof Stability of Coal Roadway Heading Face
Authors: Su Chao , Jiang Pengfei , Gong Peilin , Liu Chang , Li Peng , Liu Yuedong
Published: October 2022

One of the challenges that urgently needs to be addressed, both in current times and in the future, is to improve the heading speed of coal roadways. The roof instability of the heading face is the main factor restricting the rapid heading of coal roadways. Based on the theory of thin plate, a mechanical model of the roof in the heading face is established, the distribution law of deflection, stress, and internal force is discussed, and the supporting principle of the roof is clarified. Through a Flac3D numerical simulation, the main influencing factors of roof stability in the heading face are analyzed, including ground stress, surrounding rock strength, roadway section, unsupported distance, etc., and the regression analysis of each factor is carried out by evaluating the amount of roof subsidence. The results show that the maximum tensile stress and the corresponding bending moment of the roof appear at the fixed supported edge, and the maximum compressive stress and the maximum value of the corresponding bending moment appear at the center of the roof slightly close to the simply supported edge. In the on-site construction process, the position close to the fixed supported edge needs to be supported first. The roof subsidence has a positive exponential relationship with the stress level, a negative exponential relationship with the surrounding rock strength, a quadratic functional relationship with the roadway section, and a logarithmic relationship with the unsupported distance. In fractional support, the initial partial support can timely reduce the roof span and partially recover the confining pressure. Under certain geological and production conditions, the use of fractional support can not only effectively maintain the stability of the roadway but also speed up the heading speed. According to the research results, it is determined that in the auxiliary transportation roadway of the Caojiatan Coal Mine, the 122,110 working face adopts the fractional support model, the maximum roof subsidence is 18 mm, the roof is stable, and the monthly progress is more than 1000 m, which significantly improves the roadway heading speed.
A Harmonic Suppression SVPWM Strategy for the Asymmetric Six-Phase Motor Fed by Two-Level Six-Phase VSI Operating in the Overmodulation Region
Authors: Zhao Li , Huang Shoudao , Zheng Jian , Gao Yuan
Published: October 2022

For the asymmetric six-phase motor fed by a two-level six-phase voltage source inverter (VSI), when the modulation index is less than 0.5774, the motor operates in the linear region, and the harmonics in the Z1 − Z2 subspace can be suppressed to zero. When the modulation index is beyond 0.5774 and less than 0.6221, the motor operates in overmodulation regions, and the harmonics in the Z1 − Z2 subspace cannot be suppressed to zero. To minimize the harmonics in the Z1 − Z2 subspace for these regions, a harmonic suppression strategy, namely, harmonic suppression overmodulation strategy (HSOS), is proposed in this paper. The lower-order harmonics of the Z1 − Z2 subspace, namely, the 5th, 7th, 17th and 19th, are considered. Compared with the traditional four-vector overmodulation strategy (TFOS), the content of the 5th harmonic is reduced by about 20%, and the total harmonic distortion (THDZ1Z2) of these four kinds of harmonics is reduced by about 21% in the proposed HSOS. Finally, the simulation and experiment are carried out to verify the effectiveness of the proposed strategy.
Unipolar Arc Ignited Partial Discharge for 650-V AlGaN/GaN HEMTs during the DC Breakdown Voltage Measurement
Authors: Lee Jian-Hsing , Liao Chih-Cherng , Huang Yeh-Jen , Li Ching-Ho , Hong Li-Yang , Jou Yeh-Ning , Chen Ke-Horng
Published: October 2022

Without the Fluorinert solution and proper pad design, the high–voltage (HV) transistor used during the DC breakdown voltage (Vbk) measurement might be damaged by the partial discharge (PD) in the air if its Vbk is close to one thousand volts or more. From the waveform measurement, the PD in the air occurred at 650 V HV GaN HEMTs during the Vbk measurement, it is ignited by the unipolar arc, and it is not ignited by the avalanche breakdown. This is based on the fact that the current falls below zero ampere to become a negative current, and the voltage rises so that it is higher than the setting voltage of the DC meter at the onset of the PD, thus corresponding with the electrons, leaving the plasma to cathode, and enabling a build–in potential to exist in the plasma. Then, the PD ignites because the current starts to rise in order to allow for a positive spike current; the voltage level subsequently falls and a lower voltage reading is obtained.
Multi-Criteria Decision-Making Problem for Energy Storage Technology Selection for Different Grid Applications
Authors: Zubiria Ander , Menéndez Álvaro , Grande Hans-Jürgen , Meneses Pilar , Fernández Gregorio
Published: October 2022

Grid stability and supply security need to be maintained when generation and consumption mismatches occur. A potential solution to this problem could be using Energy Storage Technologies (EST). Since many alternatives exist, appropriate technology selection becomes a key challenge. Current research focuses on ranking and selecting the most suitable technology, regardless of the grid services to be provided. In this study, a multi-criteria decision making (MCDM) problem is formulated considering fifteen selection criteria and the opinions of five energy storage experts groups. Literature and expert consultation data have been converted to triangular fuzzy (TF) numbers to cope with ambiguity and heterogeneity and eighteen technologies have been ranked applying the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. The proposed method has been implemented on a software tool and assessed in four representative microgrid services of interest for the ENERISLA Project. The results show that pump hydro storage is the most suitable EST for frequency regulation, time shifting and seasonal storage applications, while flywheels best suit inertial response. It is concluded that the proposed methodology provides an intuitive framework for EST selection under multi-agent uncertainty and different grid application scenarios.
Features of Radiative Mixed Convective Heat Transfer on the Slip Flow of Nanofluid Past a Stretching Bended Sheet with Activation Energy and Binary Reaction
Authors: Khan Umair , Zaib Aurang , Madhukesh Javali , Elattar Samia , Eldin Sayed , Ishak Anuar , Raizah Zehba , Waini Iskandar
Published: October 2022

The current exploration aims to inspect the features of thermal radiation on the buoyancy or mixed convective fluid flow induced by nanofluid through a stretching permeable bended sheet. The impact of activation energy and binary reaction along with slip migration is taken into account to discuss the fine points of water-based alumina nanoparticle flow. The structure of the curved sheet is assumed to be stretchable and the bended texture is coiled within a circular section with radius Rb. The similarity technique is utilized to reduce the leading partial differential equations into ordinary differential equations. These reduced equations are then deciphered numerically by employing the bvp4c method. The outcomes of the model were constructed in the form of several figures and bar graphs for the case of opposing and assisting flows with varying distinct embedded control parameters. The results display that the velocity field curves escalate with a higher radius of curvature parameter while temperature and concentration profiles shrink. More precisely, the outcomes show that the temperature distribution profile increases with the increase in nanoparticle’s volume fraction as well as thermal radiation parameter. Meanwhile, the concentration and velocity fields are decelerated with higher impacts of nanoparticle volume fraction. In addition, the heat and mass transfer rates were significantly improved for the higher value of the radiation and Schmidt number. On the other hand, the growing values of the velocity slip factor decrease the shear stress. Furthermore, the results are compared with the previous results in the limiting cases and observed a tremendous harmony.
A Comprehensive Review of Demand-Side Management Based on Analysis of Productivity: Techniques and Applications
Authors: Rezaei Navid , Ahmadi Abdollah , Deihimi Mohammadhossein
Published: October 2022

Demand-side management (DSM) includes various persuasive measures to improve the use of energy; thus, it has been studied from various perspectives in the literature. Nowadays, the context of productivity has an important role in the evaluation of the electrical energy systems. Accordingly, this paper presents a platform to comprehensively contemplate the DSM from the productivity perspective that features its three aspects. First, the widespread indices of DSM are manifestly redefined, and a plenary index of DSM is introduced, reflecting both energy and investment productivity. Second, the modification of energy efficacy and consumption pattern is discussed, considering a general categorization of DSM modalities based on the pertaining index of each branch. Third, a modified model of demand response (DR) is developed to implement seven DR strategies in the smart microgrids. The simulation results demonstrate that the load factor can improve up to 8.12% with respect to the normal consumption pattern. Moreover, the load factor can be further enhanced at least by 4.22% in comparison with the customary model.
Synthesis and Plugging Performance of Poly (MMA-BA-ST) as a Plugging Agent in Oil-Based Drilling Fluid
Authors: Yang Jian , Lei Zhen , Dong Bo , Ai Zhongqiang , Peng Lin , Xie Gang
Published: October 2022

Nanopolymer was developed in order to solve the problem that the micron-scale plugging agent cannot effectively plug nanopores, which leads to instability of the wellbore. The oil-based nano plugging agent poly (MMA-BA-ST) was synthesized by Michael addition reaction using styrene, methyl methacrylate and butyl acrylate compounds as raw materials. Poly (MMA-BA-ST) has a particle size distribution of 43.98–248.80 nm, with an average particle size of 108.70 nm, and can resist high temperatures of up to 364 °C. Poly (MMA-BA-ST) has little effect on the rheological performance parameters of drilling fluids, no significant change in the emulsion breaking voltage, significant improvement in the yield point of drilling fluids and good stability of drilling fluids. The mud cake experiment, and artificial rock properties of poly (MMA-BA-ST), showed that the best-plugging effect was achieved at 0.5% addition, with a mud cake permeability of 6.3 × 10−5 mD, a plugging rate of 72.12%, an artificial core permeability of 4.1 × 10−4 mD and a plugging rate of 88.41%. The nano plugging agent poly (MMA-BA-ST) can enter the nanopore joints under the action of formation pressure to form an effective seal, thus reducing the effect of filtrate intrusion on well wall stability.
Alkali-Resistant and pH-Sensitive Water Absorbent Self-Healing Materials Suitable for Oil Well Cement
Authors: Zhao Lin , Li Ning , Yang Junhu , Wang Haijuan , Zheng Lihui , Wang Chunyu
Published: October 2022

Oil well cement microcracks cause formation fluid channeling, compromising oil and gas extraction safety. Superabsorbent polymer (SAP) can absorb water and swell to prevent fluid channeling. In this study, an alkali-resistant and pH-sensitive SAP was prepared based on the properties of oil well cement slurry. The preparation of the SAP was optimized, including monomer ratio, cross-linking agent dosage, and monomer concentration. The pH sensitivity and alkali resistance of the SAP were evaluated. The results revealed that the SAP exhibited good pH sensitivity, with the absorption rate in water being 2.18 times that of cement slurry filtrate (CSF) at 95 °C. Furthermore, the FTIR spectrum showed that the SAP had a stable molecular structure. The secondary absorption rate in water of the SAP after soaking in CSF was not different from the original absorption rate. Styrene–butadiene latex (SBL) can be used to adjust the SAP’s absorption rate. The SAP’s absorption rate had a good exponential functional relationship with SBL dosage. The SBL dosage can be determined by the functional relationships to prepare a SAP with the required properties.
Comparative Analysis of PI and ADRC Control through CHIL Real Time Simulations of a DC-DC DAB into a Multi-Terminal MVDC/LVDC Distribution Network
Authors: Chiumeo Riccardo , Raggini Diego , Veroni Alessandro , Clerici Alessio
Published: October 2022

This article presents a deep theoretical analysis of the Active Disturbance Rejection Control (ADRC) regulator for the control of first-order systems, directly compared to a “traditional” Proportional Integral (PI) regulator. To complete the theoretical study, ADRC and PI are implemented into the model of a single-phase Dual Active Bridge (DAB) converter to regulate the voltage of a Direct Current (DC) network. Facing different types of disturbances and DC network parameters variations, strengths and weaknesses of the two controllers are highlighted. ADRC and PI controls are discretized and implemented in Control Hardware In the Loop (CHIL) simulations of a single-phase DAB converter to regulate the voltage of a node of multi-terminal and multi-level DC network. By changing the DAB connection points along the MVDC network, the controlled system is stressed with different disturbances, extending the result of single-terminal network software simulations.
Profitability of Conveyor Belt Refurbishment and Diagnostics in the Light of the Circular Economy and the Full and Effective Use of Resources
Authors: Błażej Ryszard , Jurdziak Leszek , Kirjanów-Błażej Agata , Bajda Mirosław , Olchówka Dominika , Rzeszowska Aleksandra
Published: October 2022

The authors propose a new method of predictive replacements of belt sections in a conveyor belt loop with their refurbishment based on their condition recognized by specially designed diagnostic devices: DiagBelt and BeltSonic. Selection of the moment for belt replacement is made on the basis of forecasted state of its wear, when steel cable failure density exceeds the selected threshold or the percentage of belt covers abrasion exceeds the permissible level. The use of double belt refurbishment extends the total belt operation time, but without diagnostics, the reconditioning success rate is relatively low. Visual inspection allows only an uncertain assessment of cable condition. New devices give precise assessment of their condition and allow the selection of a non-linear rate of belt condition based on consecutive scans. The assessed condition of the cables is the key factor in successful belt refurbishment and obtained cost savings. Additionally, diagnostics can help extend belt life. Identified failures can be repaired in order to prevent accelerated belt degradation. The use of diagnostics in the current replacement strategy significantly improves the economic efficiency of belt reconditioning. The reuse of the belt core ensures efficient use of resources and reduces the level of waste, which fits into the circular economy.
Study of Hybrid Transmission HVAC/HVDC by Particle Swarm Optimization (PSO)
Authors: Siregar Yulianta , Pardede Credo
Published: October 2022

There are considerable power losses in Indonesia’s SUMBAGUT 150 kV transmission High Voltage Alternating Current Network (HVAC) system. These power losses and the voltage profile are critical problems in the transmission network system. This research provides one possible way to reduce power losses involving the use of a High Voltage Direct Current (HVDC) network system. Determining the location to convert HVAC into HVDC is very important. The authors of the current study used Particle Swarm Optimization (PSO) to determine the optimal location on the 150 kV SUMBAGUT HVAC transmission network system. The study results show that, before using the HVDC network system, the power loss was 68.41 MW. On the other hand, power loss with the conversion of one transmission line to HVDC was 57.31 MW for “Paya Pasir–Paya Geli” (efficiency 16.22%), 51.79 MW for “Paya Pasir–Sei Rotan” (efficiency 24.29%), and 60.8 MW for “Renun–Sisikalang” (efficiency 110.12%). The power loss with the conversion of two transmission lines to HVDC was 45.7 MW for “Paya Pasir–Paya Geli” and “Paya Pasir–Sei Rotan” (efficiency 33.19%), 44.95 MW for “Paya Pasir–Paya Geli” and “Renun–Sidikalang” (efficiency 26.98%), and 44.69 MW for “Paya Pasir–Sei Rotan” and “Renun–Sidikalang” (efficiency 34.67%). The power loss with the conversion of three transmission lines to HVDC was 38.71 MW for “Paya Pasir–Paya Geli,” “Paya Pasir–Sei Rotan,” and “Renun–Sidikalang” (efficiency 41.41%).
Fuzzy-Logic-Controlled Hybrid Active Filter for Matrix Converter Input Current Harmonics
Authors: Koduah Asare , Effah Francis Boafo
Published: October 2022

The proliferation of matrix converter interfaces coupled with traditional loads produces nonstandard and high-frequency harmonics in the range of (2 to 150) kHz in the power system. Although several research works have been conducted on passive and active filter solutions, most of these are low-frequency (below 2 kHz) solutions and are not effective under supraharmonic frequencies. An experimental study of a fuzzy-inference-system-controlled hybrid active power filter (HAPF) for the attenuation of higher frequency harmonics (above 8 kHz) is proposed. The compensational approach introduced is different from traditional approaches and the use of the fuzzy logic controller eliminates complexities involved in active filter designs. The proposed filter obtained a total harmonic distortion (THD) of 1.16% of the fundamental 50 Hz supply frequency. The performance of the proposed hybrid filter was compared with that of the proportional and integral (PI) controlled topology. The results obtained indicated superior performance of the fuzzy logic controller over the PI in terms of compensational speed, accuracy, the THD of the supply current and the overall integrity of the matrix converter. Illustrative design blocks and simulation in MATLAB/Simulink environment are provided to buttress these findings.
Data Analysis of Electricity Service in Colombia’s Non-Interconnected Zones through Different Clustering Techniques
Authors: Colmenares-Quintero Ramón Fernando , Maestre-Gongora Gina , Baquero-Almazo Marieth , Stansfield Kim E. , Colmenares-Quintero Juan Carlos
Published: October 2022

Energy determines the social, economic, and environmental aspects that enable the advancement of communities. For this reason, this paper aims to analyze the quality of the energy service in the Non-Interconnected Zones (NIZ) of Colombia. For this purpose, clustering techniques (K-means, K-medoids, divisive analysis clustering, and heatmaps) are applied for data analysis in the context of the NIZ to identify patterns or hidden information in the Colombian government data related to the state of the electricity service in these localities during the years 2019–2020. A descriptive statistical analysis and validation of the results of the clustering techniques is also carried out using R software. Through the implementation of clustering algorithms such as K-means, K-medoids, and divisive analysis clustering, potential areas for the development of renewable and alternative energy projects are identified, considering places with deficiencies in their current electricity service, higher consumption, or places with very low daily hours of electricity service. Additionally, relationships were identified in the dataset that can be considered as tools that would support decision-making for academia and industry, as well as the definition of guidelines or strategies from the government to improve energy efficiency and quality for these places, and consequently, the living conditions of the residents of Colombia’s NIZs.
Antibacterial Activity of Bacillus Strains against Acute Hepatopancreatic Necrosis Disease-Causing Vibrio campbellii in Pacific White Leg Shrimp
Authors: Jeon Hye Jin , Song Jae Won , Lee Chorong , Kim Bumkeun , Park Seon Young , Kim Ji Hyung , Han Jee Eun , Park Jae Hak
Published: October 2022

Acute hepatopancreatic necrosis disease (AHPND) is a bacterial disease caused by Vibrioparahaemolyticus. Currently, various Vibrio strains, including V. campbellii, V. owensii, and V. harveyi, have been reported as causative pathogens. Thus, controlling AHPND to maintain high production in shrimp aquaculture is difficult. We evaluated the antimicrobial activity of five Bacillus strains (B1, B3, B5, B7, and B8)—isolated from seawater in Jeju, South Korea—against 12 Vibrio strains (10 AHPND strains and 2 non-AHPND strains). All tested Bacillus strains inhibited the growth of at least one of the tested Vibrio strains in the dot-spot method. Among them, B1 and B3, the most effective Bacillus strains against the Vibrio strains, particularly against AHPND-causing V. campbellii (VcAHPND), were further used in a challenge test. After 48–60 h of VcAHPND immersion, a significantly higher survival rate was observed in the B1-treated group (100%) than in the non-Bacillus-treated group (64.3%). Based on the qPCR analysis of AHPND, the cycle threshold values were 31.63 ± 0.2 (B1-treated group) and 38.04 ± 0.58 (B3-treated group), versus 28.70 ± 0.42 in the control group. Genome sequencing and phylogenetic analysis revealed that B1 and B3 were classified as B. velezensis. The 16S rRNA sequences and complete genome sequences of B1 and B3 were deposited in GenBank.
Production Performances and Profitability of Stocking Homestead Ponds with Advanced Carp Fingerlings for Maximizing Family Nutrition and Income Generation
Authors: Hossain Mohammad Belal , Nur As-Ad Ujjaman , Sarker Md. Milon , Banik Partho , Islam Md. Monirul , Albeshr Mohammed Fahad , Arai Takaomi
Published: October 2022

Coastal homestead ponds are flooded during the rainy season and only hold water for five to six months. For coastal rural people, these ponds have a substantial impact on household nutrition and income generation. However, choosing the right culture techniques, stocking density, and seed size are necessary for fish aquaculture to be effective in this sort of seasonal pond. Hence, an adaptive field experiment was conducted to reveal the growth performance, yield and cost–benefit using advanced carp fingerling at different stocking densities in homestead ponds. Advanced fingerlings of Gibelion catla, Labeo rohita, Cirrhinus cirrhosus, and Labeo calbasu with the mean individual stocking weight of 243 ± 1.87 g, 223.56 ± 2.35 g, 155.89 ± 1.69 g, and 158.72 ± 1.35 g, respectively, were stocked at three different stocking densities, e.g., 825 kg ha−1 in T1, 560 kg ha−1 in T2 and 370 kg ha−1 in T3 and reared for 5 months. Homemade supplementary feed with protein content of 24.25% was supplied twice daily. The specific growth rate (SGR) was recorded highest at T3 for all the cultured species as L. rohita (1.15 ± 0.01% day−1), followed by G. catla (1.12 ± 0.004% day−1), L. calbasu (1.09 ± 0.01% day−1), and C. cirrhosus (0.98 ± 0.002% day−1), respectively. An inverse relationship was detected between fish growth and stocking density for all treatments. A similar pattern was observed in the survival rate, where reduced survival rates were recorded at T1 for all species. Significant variation (p < 0.05) was found among the treatments in terms of final weight, SGR, and survival rate. Economics of the carp polyculture also showed the highest net benefit (2609.77 ± 2.02 USD ha−1) and benefit–cost ratio (2.06 ± 0.002) at T3. Rearing of fish at 370 kg ha−1 stocking density yielded 129.21% and 110.96% higher production in T3 than T1 and T2, respectively. Overall, T3 treatment was more appropriate than T1 and T2 due to its low FCR, low investment but high survival rate, and net return. Therefore, stocking homestead ponds with advanced carp fingerling with a density of 370 kg per ha can be suggested as for increasing fish production and benefit in the homestead ponds of coastal rural area. In addition, further research is recommended to find out the effects of feeding and sources of seeds on the production performances.
Hamiltonian Variational Formulation of Three-Dimensional, Rotational Free-Surface Flows, with a Moving Seabed, in the Eulerian Description
Authors: Mavroeidis Constantinos P. , Athanassoulis Gerassimos A.
Published: October 2022

Hamiltonian variational principles have provided, since the 1960s, the means of developing very successful wave theories for nonlinear free-surface flows, under the assumption of irrotationality. This success, in conjunction with the recognition that almost all flows in the sea are not irrotational, raises the question of extending Hamilton’s principle to rotational free-surface flows. The Euler equations governing the bulk fluid motion have been derived by means of Hamilton’s principle since the late 1950s. Nevertheless, a complete variational formulation of the rotational water-wave problem, including the derivation of the free-surface boundary conditions, seems to be lacking until now. The purpose of the present work is to construct such a missing variational formulation. The appropriate functional is the usual Hamilton’s action, constrained by the conservation of mass and the conservation of fluid parcels’ identity. The differential equations governing the bulk fluid motion are derived as usually, applying standard methods of the calculus of variations. However, the standard methodology does not provide enough structure to obtain the free-surface boundary conditions. To overcome this difficulty, differential-variational forms of the aforementioned constraints are introduced and applied to the boundary variations of the Eulerian fields. Under this transformation, both kinematic and dynamic free-surface conditions are naturally derived, ensuring the Hamiltonian variational formulation of the complete problem. An interesting feature, appearing in the present variational derivation, is a dual possibility concerning the tangential velocity on the boundary; it may be either the same as in irrotational flow (no condition) or zero, corresponding to the small-viscosity limit. The deeper meaning and the significance of these findings seem to deserve further analysis.
Characterization of the Biological Activities of a New Polyphenol-Rich Extract from Cinnamon Bark on a Probiotic Consortium and Its Action after Enzymatic and Microbial Fermentation on Colorectal Cell Lines
Authors: De Giani Alessandra , Pagliari Stefania , Zampolli Jessica , Forcella Matilde , Fusi Paola , Bruni Ilaria , Campone Luca , Di Gennaro Patrizia
Published: October 2022

Cinnamon polyphenols are known as health-promoting agents. However, their positive impact depends on the extraction method and their bioaccessibility after digestion. In this work, cinnamon bark polyphenols were extracted in hot water and subjected to an in vitro enzymatic digestion. After a preliminary characterization of total polyphenols and flavonoids (respectively 520.05 ± 17.43 µgGAeq/mg and 294.77 ± 19.83 µgCATeq/mg powder extract), the extract antimicrobial activity was evidenced only against Staphylococcus aureus and Bacillus subtilis displaying a minimum inhibition growth concentration value of 2 and 1.3 mg/mL, respectively, although it was lost after in vitro extract digestion. The prebiotic potential was evaluated on probiotic Lactobacillus and Bifidobacterium strains highlighting a high growth on the in vitro digested cinnamon bark extract (up to 4 × 108 CFU/mL). Thus, the produced SCFAs and other secondary metabolites were extracted from the broth cultures and determined via GC-MSD analyses. The viability of healthy and tumor colorectal cell lines (CCD841 and SW480) was assayed after the exposition at two different concentrations (23 and 46 µgGAeq/mL) of the cinnamon extract, its digested, and the secondary metabolites produced in presence of cinnamon extract or its digested, showing positive protective effects against a tumorigenic condition.
The Effect of the Addition of Low-Alkaloid Lupine Flour on the Glycemic Index In Vivo and the Physicochemical Properties and Cooking Quality of Durum Wheat Pasta
Authors: Krawęcka Ada , Sobota Aldona , Zarzycki Piotr
Published: October 2022

The aim of this research was to determine the effect of the addition of lupine flour (LF) on the values of the glycemic index (GI) and glycemic load (GL), physicochemical properties, and cooking quality of durum semolina pasta. The pasta was enriched with 0–25% of lupine flour (LF0-LF25). Additionally, 7.5 and 20% of oat β-glucans, 5% of vital gluten, and 20% of millet flour were used in a selected sample. The addition of 7.5% β-glucans and 5% vital gluten to the product resulted in only a slight decrease in the GI of the products. A significant decrease in pasta GI was noted after the addition of 20% of lupine flour. The product enriched with 20% of lupine flour, 20% of β-glucans, and 20% of millet flour had the lowest glycemic index and glycemic load (GI = 33.75%, GL = 7.2%, respectively). At the same time, the lupine-flour-enriched products were characterized by an increased concentration of protein, fat, ash, and dietary fiber. The addition of lupine flour at the level of up to 20% yielded functional products characterized by good cooking quality.
Aqueous Extract from Cuminum cyminum L. Seed Alleviates Ovalbumin-Induced Allergic Rhinitis in Mouse via Balancing of Helper T Cells
Authors: Ishida Momoko , Miyagawa Fuka , Nishi Kosuke , Sugahara Takuya
Published: October 2022

Cuminum cyminum L. (cumin) seeds are widely used as a spice. Although we previously reported that the aqueous extract of cumin seeds suppresses the degranulation of rat basophilic RBL-2H3 cells, it has not been clarified whether the extract alleviates actual allergy symptoms in vivo. Therefore, in this study, we investigated the effect of oral administration of cumin seed aqueous extract (CAE) in ovalbumin (OVA)-induced allergic rhinitis. BALB/c mice were randomly divided into the following three groups: control group (five mice), OVA group (five mice), and OVA + CAE group (five mice). Allergic rhinitis was induced by sensitization (intraperitoneal, 25 μg OVA and 1.98 mg aluminum hydroxide gel) followed by challenge (intranasal, 400 μg OVA). The oral administration of CAE (25 mg/kg) reduced the sneezing frequency of OVA-induced allergic rhinitis model mice. In addition to reducing the serum immunoglobulin E and IL-4 levels, the oral administration of CAE reduced the production of T-helper type-2 (Th2) cytokines (IL-4, IL-5, IL-10, and IL-13) in the splenocytes of the model mice. Furthermore, a significant increase in the ratio of Th1 to Th2 cells was observed in the CAE-administered group. Our findings suggest that the ingestion of CAE improves T cell balance, the dominant state of Th2, and alleviates allergic rhinitis symptoms.
The Characterization of a Novel D-allulose 3-Epimerase from Blautia produca and Its Application in D-allulose Production
Authors: Tang Xinrui , An Yingfeng , Iqbal Muhammad Waheed , Cong Hongri , Zhang Guoyan , Zhang Yufei , Ravikumar Yuvaraj , Zabed Hossain M. , Zhao Mei , Zhou Haixing , Qi Xianghui
Published: October 2022

D-allulose is a natural rare sugar with important physiological properties that is used in food, health care items, and even the pharmaceutical industry. In the current study, a novel D-allulose 3-epimerase gene (Bp-DAE) from the probiotic strain Blautia produca was discovered for the production and characterization of an enzyme known as Bp-DAE that can epimerize D-fructose into D-allulose. Bp-DAE was strictly dependent on metals (Mn2+ and Co2+), and the addition of 1 mM of Mn2+ could enhance the half-life of Bp-DAE at 55 °C from 60 to 180 min. It exhibited optimal activity in a pH of 8 and 55 °C, and the Km values of Bp-DAE for the different substrates D-fructose and D-allulose were 235.7 and 150.7 mM, respectively. Bp-DAE was used for the transformation from 500 g/L D-fructose to 150 g/L D-allulose and exhibited a 30% of conversion yield during biotransformation. Furthermore, it was possible to employ the food-grade microbial species Bacillus subtilis for the production of D-allulose using a technique of whole-cell catalysis to circumvent the laborious process of enzyme purification and to obtain a more stable biocatalyst. This method also yields a 30% conversion yield.
Quality Characteristics of Novel Sourdough Breads Made with Functional Lacticaseibacillus paracasei SP5 and Prebiotic Food Matrices
Authors: Kazakos Stavros , Mantzourani Ioanna , Plessas Stavros
Published: October 2022

Lacticaseibacillus paracasei SP5, isolated from kefir, was assessed as a starter culture for sourdough bread making in freeze-dried form, both free (BSP5 bread) and immobilised on wheat bran (BIWB) and on a traditional flour/sour milk food, ‘trahanas’ (BITR). Physicochemical characteristics, shelf-life, volatilome, phytic acid, and sensory properties of the breads were evaluated. The BITR breads had higher acidity (9.05 ± 0.14 mL of 0.1 M NaOH/10 g) and organic acid content (g/Kg; 2.90 ± 0.05 lactic, 1.04 ± 0.02 acetic), which justifies the better resistance against mould and rope spoilage (>10 days). The highest number of volatiles (35) and at higher concentration (11.14 μg/g) were also found in BITR, which is in line with the sensory (consumer) evaluation regarding flavour. Finally, higher reduction of phytate (an antinutrient) was observed in all L. paracasei SP5 sourdoughs (83.3–90.7%) compared to the control samples (71.4%). The results support the use of the new strain for good quality sourdough bread.
Hydrogels, Oleogels and Bigels as Edible Coatings of Sardine Fillets and Delivery Systems of Rosemary Extract
Authors: Kanelaki Aikaterini , Zampouni Konstantina , Mourtzinos Ioannis , Katsanidis Eugenios
Published: October 2022

Edible coatings provide an alternative way to reduce packaging requirements and extend the shelf life of foods by delaying oxidation and microbial spoilage. Hydrogels, oleogels and bigels were applied as coatings on fresh sardine fillets. The effectiveness of these coatings as delivery systems of rosemary extract (RE) was also evaluated. Three groups of sardine fillet treatments were prepared: (i) the control (C), which comprised sardine fillets without coating, (ii) sardine fillets with plain hydrogel (H), oleogel (O) or bigel (BG) coatings, and (iii) sardine fillets with RE incorporated into the H, O and BG coatings. The different treatments were evaluated for lipid oxidation (TBA test), total volatile basic nitrogen (TVB-N) and microbiological growth during cold storage at 4 °C. Results showed that hydrogel, oleogel and bigel coatings delayed oxidation. The incorporation of RE into coatings significantly retarded lipid oxidation but did not affect the proliferation of microorganisms during storage. When RE was incorporated in the oleogel phase of the bigel coating, it produced significantly lower TVB-N values compared to the control and BG treatments. The incorporation of RE into the oleogel phase of the bigel coating may be a promising method of maintaining the storage quality of the sardine fillets stored at refrigerated temperatures.