bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Analysis of the Antioxidative and Hepatoprotective Activities of Dimethyl Diphenyl Bicarboxylate in Four Animal Models of Hepatic Injury
Authors: Wang Jing-Hua , Hwang Seung-Ju , Son Chang-Gue
Published: September 2021

As a well-known hepatoprotective and antioxidant agent, dimethyl diphenyl bicarboxylate (DDB) has frequently been employed to remedy various liver diseases. However, it is still uncertain whether DDB exerts consistent hepatoprotective and antioxidative activities against varying degrees of hepatic damage. Therefore, DDB (100, 25, 5, or 50 mg/kg depending on the model) was administered to animals in four representative models of liver injury (CCl4 chemical acute model, DMN subchronic model, TAA chronic model, and restraint stress psychological acute model). Horizontal comparative analysis indicated that DDB significantly lowered the excess serum AST and ALT levels in the CCl4 and DMN models but not in the TAA and restraint stress models. In accordance with this result, DDB markedly reduced oxidative stress indices (hepatic MDA and ROS) but restored five main antioxidant components (GSH content, GSH-peroxidase, GSH-reductase, SOD, and catalase activity) in the CCl4 and DMN models. DDB failed to normalize oxidative stressors in the restraint stress-induced injury model and restore these five antioxidant components in the TAA model. Overall, our results produced a comprehensive overview of the effects of DDB on oxidative stressors and the main antioxidative components using four animal models. These findings will provide valuable clues to guide therapeutic clinical applications.
A Corpus-Based Study of Linguistic Deception in Spanish
Authors: Almela Ángela
Published: September 2021

In the last decade, fields such as psychology and natural language processing have devoted considerable attention to the automatization of the process of deception detection, developing and employing a wide array of automated and computer-assisted methods for this purpose. Similarly, another emerging research area is focusing on computer-assisted deception detection using linguistics, with promising results. Accordingly, in the present article, the reader is firstly provided with an overall review of the state of the art of corpus-based research exploring linguistic cues to deception as well as an overview on several approaches to the study of deception and on previous research into its linguistic detection. In an effort to promote corpus-based research in this context, this study explores linguistic cues to deception in the Spanish written language with the aid of an automatic text classification tool, by means of an ad hoc corpus containing ground truth data. Interestingly, the key findings reveal that, although there is a set of linguistic cues which contributes to the global statistical classification model, there are some discursive differences across the subcorpora, yielding better classification results on the analysis conducted on the subcorpus containing emotionally loaded language.
Health Promoting Effect of Phyllanthus emblica and Azadiractha indica against Advanced Glycation End Products Formation
Authors: A. Alsahli Mohammed , Anwar Shehwaz , Alzahrani Faisal M. , Almatroudi Ahmad , Alfheeaid Hani , Khan Amjad A. , Allemailem Khaled S. , Almatroodi Saleh A. , Rahmani Arshad Husain
Published: September 2021

Oxidative stress is linked with inflammation, diabetic complications, and advanced glycation end products formation. Intake of flavonoid-rich foods has been reported to have a beneficial effect on human health. The aim of this study was to verify the therapeutic potential of Phyllanthusemblica and Azadiractha indica against glycation and other oxidative stress-induced complications such as inflammation using in vitro study. Ethanol extracts of Phyllanthus emblica fruit pulp and dried leaf of Azadiractha indica were prepared to investigate in vitro anti-inflammatory and anti-glycating potentials. In a DPPH assay, the EC50 value of extract of P. emblica and A. indica was found to be 1532.36 ± 0.17 and 1380.61 ± 0.27 µg/mL, respectively. The FRAP value of P. emblica and A. indica extract was 86.6 and 32.12 µg ascorbic acid/100 mg dry weight of the extract. The maximum percentage of H2O2 scavenging activity was 71.30% and 67.38%, respectively. Extracts of P. emblica and A. indica showed maximum inhibition of heat-induced BSA denaturation by 62.42% and 53.00%, heat-induced denaturation of egg albumin, by 50.84%% and 44.31%, and heat-induced hemolysis by 54.44% and 50.21%. Both extracts (600 µg/mL) significantly reduced the browning, structural changes, aggregation, and AGEs formation. Our biophysical studies confirmed the AGEs formation was inhibiting the potential of extracts. Thus, our findings confirm that these extracts are a rich source of antioxidants and may be utilized to prevent the oxidative stress-induced destruction of biomolecules, glycation, and in the therapy of a variety of health problems, including inflammation. Further, a combination of extracts of P. emblica and A. indica may be extremely useful in preventing and treating health problems.
Combining Signal Features of Ground-Penetrating Radar to Classify Moisture Damage in Layered Building Floors
Authors: Klewe Tim , Strangfeld Christoph , Ritzer Tobias , Kruschwitz Sabine
Published: September 2021

To date, the destructive extraction and analysis of drilling cores is the main possibility to obtain depth information about damaging water ingress in building floors. The time- and cost-intensive procedure constitutes an additional burden for building insurances that already list piped water damage as their largest item. With its high sensitivity for water, a ground-penetrating radar (GPR) could provide important support to approach this problem in a non-destructive way. In this research, we study the influence of moisture damage on GPR signals at different floor constructions. For this purpose, a modular specimen with interchangeable layers is developed to vary the screed and insulation material, as well as the respective layer thickness. The obtained data set is then used to investigate suitable signal features to classify three scenarios: dry, damaged insulation, and damaged screed. It was found that analyzing statistical distributions of A-scan features inside one B-scan allows for accurate classification on unknown floor constructions. Combining the features with multivariate data analysis and machine learning was the key to achieve satisfying results. The developed method provides a basis for upcoming validations on real damage cases.
UWB and MEMS IMU Integrated Positioning Algorithm for a Work-Tool Tracking System
Authors: Kwon Seong-Geun , Kwon Oh-Jun , Kwon Ki-Ryong , Lee Suk-Hwan
Published: September 2021

In this paper, we address a system that can accurately locate and monitor work tools in a complex assembly process, such as automotive production. Our positioning monitoring system is positioned by a combined sensor of the UWB module and the MEMS IMU (inertial measuring unit) sensor based on the extended Kalman filter. The MEMS IMU sensor provides the positioning calibration information. The proposed method incorporates IMU and UWB positioning to compensate for errors that can only occur in UWB positioning through the extended Kalman filter (EKT). This EKT is improved by the error dynamic equation derived from the sparse state-space matrix. Also, the proposed method computes the transmission time and distance between the tag and anchor of the UWB module by the TWR (two-way range) system. The tag of a mobile node, which is attached to a moving tool, measures the position of the work tool and transmits the position coordinate data to the anchor. Here, the proposed method uses the trilateration localization method by the confidence distance compensation to prevent the distance error by obstacles and changes in the indoor environment. Experimental results verified that the proposed method confirms whether a specific tool is accurately used according to the prescribed regulations and has more positioning accuracy than the conventional methods.
Investigation of the Influences of Thrust Loads Resulted by Helix Angle Directions of Planetary Gear Sets on Bearing Power Losses in Automotive Planetary Gear Trains
Authors: Kwon Hyun Sik
Published: September 2021

In the recent automotive industries, automotive technologies for improving fuel efficiency have focused on the developments of reducing power losses in a transmission. As a well-developed and conventional power transmitting system, an automatic transmission is still widely used in many automotive vehicles. The automatic transmission is co-axially designed with several planetary gear sets and other mechanical parts. The co-axial arrangements and gear helix angles make the transmission necessarily include bearings for supporting loads and allowing relative rotations. In this study, the influences of thrust loads yielded by helix angle directions of planetary gear sets on bearing power losses are presented by performing the structural and power loss analysis. Bearing power losses consist of mechanical and spin power losses. For calculating thrust loads and bearing rotations, a complete transmission model is constructed by using an example structure, and structural analysis is performed for the combinations of helix angle directions of the gear sets. Finally, bearing power losses are computed by using the bearing power loss model, and the results of the entire combinations of helix angle directions are discussed.
The NMD Pathway Regulates GABARAPL1 mRNA during the EMT
Authors: Baudu Timothée , Parratte Chloé , Perez Valérie , Ancion Marie , Millevoi Stefania , Hervouet Eric , Peigney Anne , Peixoto Paul , Overs Alexis , Herfs Michael , Fraichard Annick , Guittaut Michaël , Baguet Aurélie
Published: September 2021

EMT is a reversible cellular process that is linked to gene expression reprogramming, which allows for epithelial cells to undergo a phenotypic switch to acquire mesenchymal properties. EMT is associated with cancer progression and cancer therapeutic resistance and it is known that, during the EMT, many stress response pathways, such as autophagy and NMD, are dysregulated. Therefore, our goal was to study the regulation of ATG8 family members (GABARAP, GABARAPL1, LC3B) by the NMD and to identify molecular links between these two cellular processes that are involved in tumor development and metastasis formation. IHC experiments, which were conducted in a cohort of patients presenting lung adenocarcinomas, showed high GABARAPL1 and low UPF1 levels in EMT+ tumors. We observed increased levels of GABARAPL1 correlated with decreased levels of NMD factors in A549 cells in vitro. We then confirmed that GABARAPL1 mRNA was indeed targeted by the NMD in a 3′UTR-dependent manner and we identified four overlapping binding sites for UPF1 and eIF4A3 that are potentially involved in the recognition of this transcript by the NMD pathway. Our study suggests that 3′UTR-dependent NMD might be an important mechanism that is involved in the induction of autophagy and could represent a promising target in the development of new anti-cancer therapies.
Searching for G-Quadruplex-Binding Proteins in Plants: New Insight into Possible G-Quadruplex Regulation
Authors: Volná Adriana , Bartas Martin , Nezval Jakub , Špunda Vladimír , Pečinka Petr , Červeň Jiří
Published: September 2021

G-quadruplexes are four-stranded nucleic acid structures occurring in the genomes of all living organisms and viruses. It is increasingly evident that these structures play important molecular roles; generally, by modulating gene expression and overall genome integrity. For a long period, G-quadruplexes have been studied specifically in the context of human promoters, telomeres, and associated diseases (cancers, neurological disorders). Several of the proteins for binding G-quadruplexes are known, providing promising targets for influencing G-quadruplex-related processes in organisms. Nonetheless, in plants, only a small number of G-quadruplex binding proteins have been described to date. Thus, we aimed to bioinformatically inspect the available protein sequences to find the best protein candidates with the potential to bind G-quadruplexes. Two similar glycine and arginine-rich G-quadruplex-binding motifs were described in humans. The first is the so-called “RGG motif”-RRGDGRRRGGGGRGQGGRGRGGGFKG, and the second (which has been recently described) is known as the “NIQI motif”-RGRGRGRGGGSGGSGGRGRG. Using this general knowledge, we searched for plant proteins containing the above mentioned motifs, using two independent approaches (BLASTp and FIMO scanning), and revealed many proteins containing the G4-binding motif(s). Our research also revealed the core proteins involved in G4 folding and resolving in green plants, algae, and the key plant model organism, Arabidopsis thaliana. The discovered protein candidates were annotated using STRINGdb and sorted by their molecular and physiological roles in simple schemes. Our results point to the significant role of G4-binding proteins in the regulation of gene expression in plants.
Clinical Characteristics, Care Trajectories and Mortality Rate of SARS-CoV-2 Infected Cancer Patients: A Multicenter Cohort Study
Authors: Benderra Marc-Antoine , Aparicio Ainhoa , Leblanc Judith , Wassermann Demian , Kempf Emmanuelle , Galula Gilles , Bernaux Mélodie , Canellas Anthony , Moreau Thomas , Bellamine Ali , Spano Jean-Philippe , Daniel Christel , Champ Julien , Canouï-Poitrine Florence , Gligorov Joseph ,   on Behalf of the AP-HP/Universities/INSERM COVID-19 Research Collaboration,   Cancer AP-HP Group COVID-19 Task Force,   AP-HP Covid CDW Initiative (ACCI)
Published: September 2021

Background: COVID-19 may be more frequent and more severe in cancer patients than in other individuals. Our aims were to assess the rate of COVID-19 in hospitalized cancer patients, to describe their demographic characteristics, clinical features and care trajectories, and to assess the mortality rate. Methods: This multicenter cohort study was based on the Electronic Health Records of the Assistance Publique-Hôpitaux de Paris (AP-HP). Cancer patients with a diagnosis of COVID-19 between 3 March and 19 May 2020 were included. Main outcome was all-cause mortality within 30 days of COVID-19 diagnosis. Results: A total of 29,141 cancer patients were identified and 7791 (27%) were tested for SARS-CoV-2. Of these, 1359 (17%) were COVID-19-positive and 1148 (84%) were hospitalized; 217 (19%) were admitted to an intensive care unit. The mortality rate was 33% (383 deaths). In multivariate analysis, mortality-related factors were male sex (aHR = 1.39 [95% CI: 1.07–1.81]), advanced age (78–86 y: aHR = 2.83 [95% CI: 1.78–4.51] vs. <66 y; 86–103 y: aHR = 2.61 [95% CI: 1.56–4.35] vs. <66 y), more than two comorbidities (aHR = 2.32 [95% CI: 1.41–3.83]) and C-reactive protein >20 ng/mL (aHR = 2.20 [95% CI: 1.70–2.86]). Primary brains tumors (aHR = 2.19 [95% CI: 1.08–4.44]) and lung cancer (aHR = 1.66 [95% CI: 1.02–2.70]) were associated with higher mortality. Risk of dying was lower among patients with metabolic comorbidities (aHR = 0.65 [95% CI: 0.50–0.84]). Conclusions: In a hospital-based setting, cancer patients with COVID-19 had a high mortality rate. This mortality was mainly driven by age, sex, number of comorbidities and presence of inflammation. This is the first cohort of cancer patients in which metabolic comorbidities were associated with a better outcome.
Machine-Learning Assisted Discrimination of Precancerous and Cancerous from Healthy Oral Tissue Based on Multispectral Autofluorescence Lifetime Imaging Endoscopy
Authors: Duran-Sierra Elvis , Cheng Shuna , Cuenca Rodrigo , Ahmed Beena , Ji Jim , Yakovlev Vladislav V. , Martinez Mathias , Al-Khalil Moustafa , Al-Enazi Hussain , Cheng Yi-Shing Lisa , Wright John , Busso Carlos , Jo Javier A.
Published: September 2021

Multispectral autofluorescence lifetime imaging (maFLIM) can be used to clinically image a plurality of metabolic and biochemical autofluorescence biomarkers of oral epithelial dysplasia and cancer. This study tested the hypothesis that maFLIM-derived autofluorescence biomarkers can be used in machine-learning (ML) models to discriminate dysplastic and cancerous from healthy oral tissue. Clinical widefield maFLIM endoscopy imaging of cancerous and dysplastic oral lesions was performed at two clinical centers. Endoscopic maFLIM images from 34 patients acquired at one of the clinical centers were used to optimize ML models for automated discrimination of dysplastic and cancerous from healthy oral tissue. A computer-aided detection system was developed and applied to a set of endoscopic maFLIM images from 23 patients acquired at the other clinical center, and its performance was quantified in terms of the area under the receiver operating characteristic curve (ROC-AUC). Discrimination of dysplastic and cancerous from healthy oral tissue was achieved with an ROC-AUC of 0.81. This study demonstrates the capabilities of widefield maFLIM endoscopy to clinically image autofluorescence biomarkers that can be used in ML models to discriminate dysplastic and cancerous from healthy oral tissue. Widefield maFLIM endoscopy thus holds potential for automated in situ detection of oral dysplasia and cancer.
Hypofractionated Stereotactic Radiotherapy for the Treatment of Benign Intracranial Meningiomas: Long-Term Safety and Efficacy
Authors: Nguyen Eric K. , Pond Gregory R. , Greenspoon Jeffrey N. , Whitton Anthony C. , Hann Crystal
Published: September 2021

Introduction: Hypofractionated stereotactic radiotherapy (hSRT) has emerged as an alternative to single-fraction stereotactic radiosurgery (SRS) and conventionally fractionated radiotherapy for the treatment of intracranial meningiomas (ICMs). However, there is a need for data showing long-term efficacy and complication rates, particularly for larger tumors in sensitive locations. Methods: A retrospective review was conducted on adult patients with ICMs seen at a tertiary care center. Eligible patients were treated with the CyberKnife platform and had a planned treatment course of 3–5 fractions from 2011–2020. The local control was assessed based on radiographic stability and the late toxicity/radionecrosis rates were recorded. Radiographic progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier method. Results: In total, 62 patients (age 26–87) with 67 treated tumors were included in this study with a median follow-up of 64.7 months. RT was delivered as the primary treatment in 62.7% of cases and for recurrence in 37.3%. The most common tumor locations were the convexity of the brain and the base of the skull. The tumor sizes ranged from 0.1–51.8 cc and the median planning target volume was 4.9 cc. The most common treatment schedule was 18 Gy in 3 fractions. The five-year PFS and OS were 85.2% and 91.0%, respectively. The late grade III/IV toxicity rate was 3.2% and the radionecrosis rate was 4.8%. Conclusions: Based on our data, hSRT remains an effective modality to treat low-grade ICMs with acceptable long-term toxicity and radionecrosis rates. hSRT should be offered to patients who are not ideal candidates for SRS while preserving the benefits of hypofractionation.
Quantum Walk on the Generalized Birkhoff Polytope Graph
Authors: Cação Rafael , Cortez Lucas , de Farias Ismael , Kozyreff Ernee , Khatibi Moqadam Jalil , Portugal Renato
Published: September 2021

We study discrete-time quantum walks on generalized Birkhoff polytope graphs (GBPGs), which arise in the solution-set to certain transportation linear programming problems (TLPs). It is known that quantum walks mix at most quadratically faster than random walks on cycles, two-dimensional lattices, hypercubes, and bounded-degree graphs. In contrast, our numerical results show that it is possible to achieve a greater than quadratic quantum speedup for the mixing time on a subclass of GBPG (TLP with two consumers and m suppliers). We analyze two types of initial states. If the walker starts on a single node, the quantum mixing time does not depend on m, even though the graph diameter increases with it. To the best of our knowledge, this is the first example of its kind. If the walker is initially spread over a maximal clique, the quantum mixing time is O(m/ϵ), where ϵ is the threshold used in the mixing times. This result is better than the classical mixing time, which is O(m1.5/ϵ).
Cross-Correlations in Meat Prices in Brazil: A Non-Linear Approach Using Different Time Scales
Authors: Quintino Derick , Telo da Gama José , Ferreira Paulo
Published: September 2021

Brazil is one of the world’s largest producers and exporters of cattle, chicken and swine. Therefore, co-movements of Brazilian meat prices are important for both domestic and foreign stakeholders. We propose to analyse the cross-correlation between meat prices in Brazil, namely, cattle, swine and chicken, including also in the analysis information from some commodities, namely maize, soya beans, oil, and the Brazilian exchange rate. Our sample covers the recent period which coincided with extensive macroeconomic and institutional changes in Brazil, from 2011 to 2020, and is divided in two periods: (i) presidential pre-impeachment (P1), occurring in August 2016, and; (ii) post-impeachment (P2). Our results indicate that in P1, only the prices of swine and chicken showed a positive and strong correlation over time, and that cattle showed some positive correlation with chicken only in the short run. In P2, there was also a positive and consistent correlation between swine and chicken, and only a positive association with swine and cattle in the long run. For more spaced time scales (days), the changes in the degree of correlation were significant only in the long run for swine and cattle.
Workplace Incivility and Job Satisfaction: Mediation of Subjective Well-Being and Moderation of Forgiveness Climate in Health Care Sector
Authors: Khan Muhammad Safdar , Elahi Natasha Saman , Abid Ghulam
Published: September 2021

Our study investigates the role of subjective well-being and forgiveness climate between workplace incivility and job satisfaction. Drawing on conservation of resource theory, we proposed a model in which workplace incivility is associated with job satisfaction through subjective wellbeing, and forgiveness climate moderates this association. Data was collected through a survey method from 672 nurses and doctors in the health care sector at two different times. Respondents completed workplace incivility and subjective well-being scale at Time 1, and a forgiveness climate and job satisfaction scale at time 2. Findings through PROCESS Macros (Model 5) show that workplace incivility has a negative influence on job satisfaction and subjective well-being. Subjective well-being plays a mediating role in the negative effect of workplace incivility on job satisfaction. Moreover, forgiveness climate moderates the relationship between workplace incivility and job satisfaction. The implications for practice and research are discussed.
A Low-Latency, Low-Power FPGA Implementation of ECG Signal Characterization Using Hermite Polynomials
Authors: Desai Madhav P. , Caffarena Gabriel , Jevtic Ruzica , Márquez David G. , Otero Abraham
Published: September 2021

Automatic ECG signal characterization is of critical importance in patient monitoring and diagnosis. This process is computationally intensive, and low-power, online (real-time) solutions to this problem are of great interest. In this paper, we present a novel, dedicated hardware implementation of the ECG signal processing chain based on Hermite functions, aiming for real-time processing. Starting from 12-bit ADC samples of the ECG signal, the hardware implements filtering, peak and QRS detection, and least-squares Hermite polynomial fit on heartbeats. This hardware module can be used to compress ECG data or to perform beat classification. The hardware implementation has been validated on a Field Programmable Gate Array (FPGA). The implementation is generated using an algorithm-to-hardware compiler tool-chain and the resulting hardware is characterized using a low-cost off-the-shelf FPGA card. The single-beat best-fit computation latency when using six Hermite basis polynomials is under 1 s with a throughput of 3 beats/s and with an average power dissipation around 28 mW, demonstrating true real-time applicability.
A Hybrid-Driven Optimization Framework for Fixed-Wing UAV Maneuvering Flight Planning
Authors: Zhang Renshan , Cao Su , Zhao Kuang , Yu Huangchao , Hu Yongyang
Published: September 2021

Performing autonomous maneuvering flight planning and optimization remains a challenge for unmanned aerial vehicles (UAVs), especially for fixed-wing UAVs due to its high maneuverability and model complexity. A novel hybrid-driven fixed-wing UAV maneuver optimization framework, inspired by apprenticeship learning and nonlinear programing approaches, is proposed in this paper. The work consists of two main aspects: (1) Identifying the model parameters for a certain fixed-wing UAV based on the demonstrated flight data performed by human pilot. Then, the features of the maneuvers can be described by the positional/attitude/compound key-frames. Eventually, each of the maneuvers can be decomposed into several motion primitives. (2) Formulating the maneuver planning issue into a minimum-time optimization problem, a novel nonlinear programming algorithm was developed, which was unnecessary to determine the exact time for the UAV to pass by the key-frames. The simulation results illustrate the effectiveness of the proposed framework in several scenarios, as both the preservation of geometric features and the minimization of maneuver times were ensured.
Modified Variable Step-Size Incremental Conductance MPPT Technique for Photovoltaic Systems
Authors: Owusu-Nyarko Isaac , Elgenedy Mohamed A. , Abdelsalam Ibrahim , Ahmed Khaled H.
Published: September 2021

A highly efficient photovoltaic (PV) system requires a maximum power point tracker to extract peak power from PV modules. The conventional variable step-size incremental conductance (INC) maximum power point tracking (MPPT) technique has two main drawbacks. First, it uses a pre-set scaling factor, which requires manual tuning under different irradiance levels. Second, it adapts the slope of the PV characteristics curve to vary the step-size, which means any small changes in PV module voltage will significantly increase the overall step-size. Subsequently, it deviates the operating point away from the actual reference. In this paper, a new modified variable step-size INC algorithm is proposed to address the aforementioned problems. The proposed algorithm consists of two parts, namely autonomous scaling factor and slope angle variation algorithm. The autonomous scaling factor continuously adjusts the step-size without using a pre-set constant to control the trade-off between convergence speed and tracking precision. The slope angle variation algorithm mitigates the impact of PV voltage change, especially during variable irradiance conditions to improve the MPPT efficiency. The theoretical investigations of the new technique are carried out while its practicability is confirmed by simulation and experimental results.
Microalgal Hydrogen Production in Relation to Other Biomass-Based Technologies—A Review
Authors: Dębowski Marcin , Dudek Magda , Zieliński Marcin , Nowicka Anna , Kazimierowicz Joanna
Published: September 2021

Hydrogen is an environmentally friendly biofuel which, if widely used, could reduce atmospheric carbon dioxide emissions. The main barrier to the widespread use of hydrogen for power generation is the lack of technologically feasible and—more importantly—cost-effective methods of production and storage. So far, hydrogen has been produced using thermochemical methods (such as gasification, pyrolysis or water electrolysis) and biological methods (most of which involve anaerobic digestion and photofermentation), with conventional fuels, waste or dedicated crop biomass used as a feedstock. Microalgae possess very high photosynthetic efficiency, can rapidly build biomass, and possess other beneficial properties, which is why they are considered to be one of the strongest contenders among biohydrogen production technologies. This review gives an account of present knowledge on microalgal hydrogen production and compares it with the other available biofuel production technologies.
Analysis of the RES Potential in Accordance with the Energy Policy of the European Union
Authors: Jałowiec Tomasz , Wojtaszek Henryk
Published: September 2021

There is a need to reduce carbon-based energy and replace it with clean energy in order to counteract the negative effects of climate change. The increase in renewable energy sources may result in savings and the increasing cost of maintaining carbon-based energy. Worldwide involvement is required. The fulfillment of conditions by individual states does not solve the problem. The COVID-19 pandemic has slowed economic growth. It turns out that economic growth is not always associated with increased investments in RES (existing or emerging new clean energy points). We have a new epidemiological threat—Delta—which could become large. This will not improve the situation. Germany is an exemplary country for benchmarking in the field of renewable energy. The worrying fact is that Poland, despite economic growth, does not achieve an even growth in RES. Each of us is required to be involved, to be open to innovation and to act in accordance with the energy policy of the European Union. Basic management functions (planning, organizing, motivating and controlling) are also essential. Failure to meet the demands of the energy policy should be thoroughly verified and consequences should be drawn in order to involve the whole world. The authors thoroughly analyzed many factors that have a significant impact on the success in stopping climate change and increasing RES. With the increase in energy demand, renewable energy is introduced to a greater extent. Additionally, coal energy will be more expensive to maintain. The more RES, the more expensive the energy obtained from mine sources. The investment is an opportunity to meet the demands of RES, but investors are currently only interested in investing in renewable energy in highly developed countries. The decision-making process regarding the implementation of renewable energy sources not only consists in a radical decision to introduce changes, but also in the fulfillment of a number of assumptions regarding the energy policy controlled by the authorities of a given state as part of this action. There is a risk (fear) in underdeveloped countries that they will not be able to finalize this project, either due to the lack of investor interest or the lack of real opportunities due to the failure to meet the guidelines of the energy policy of a given country. It is advisable that state governments facilitate the process as much as possible so that even less developed countries could take advantage of this postulate.
Design and Pinch Analysis of a GFT Process for Production of Biojet Fuel from Biomass and Plastics
Authors: López-Fernández Alejandro , Bolonio David , Amez Isabel , Castells Blanca , Ortega Marcelo , García-Martínez María-Jesús
Published: September 2021

Environmental problems are frequently related to energy use, estimated to grow at 1.6% per year until 2035. The transport sector accounts for 30% of energy demand and aviation is growing around 2.6% per year. Thus, low-emissions policies promote the use of sustainable aviation fuels. This work simulates a gasification and Fischer-Tropsch process to obtain biojet fuel from biomass and plastic waste. Syngas obtained through cogasification is purified by amine scrubbing and subjected to a Fischer-Tropsch process to produce hydrocarbons, which are upgraded for optimal fuel properties. Pinch analysis is applied to minimize energy usage, while Rankine cycles and a cooling tower are designed to cover the demand of electricity and cooling water. Results show that mass yields of the process towards biofuels are 13.06%, with an output of 1697.45 kg/h of biojet fuel. Density, kinematic viscosity, pour and flammability points and the lower calorific value of the biojet fuel comply with the ASTM D7566 standard. Pinch analysis allows to reduce 41.58% and 100% of cooling and heating demands, respectively, using biomass as renewable energy for heating. Moreover, steam generation covers 38.73% of the required electricity. The produced biojet fuel emits 20.14 gCO2eq/MJ and has a minimum selling price of 1.37 EUR/L.
High Flexibility Hybrid Architecture Real-Time Simulation Platform Based on Field-Programmable Gate Array (FPGA)
Authors: Cheng Ruyun , Yao Li , Yan Xinyang , Zhang Bingda , Jin Zhao
Published: September 2021

With the expansion of system scale and the reduction in simulation step size, the design of a power system real-time simulation platform faces many difficulties. The interactive operation of real-time simulation presents the characteristics of phased and centralized. This paper proposes selecting the appropriate simulation method for each sub-network according to the system operation requirements, and the sub-network simulation method can be changed with the change in system operation requirements in the simulation process. In order to change the sub-network simulation method in the simulation process, a high flexibility hybrid architecture real-time simulation platform based on FPGA was designed. The main body of the architecture runs in the high control mode of instruction flow and uses instruction flexibility to realize the requirement of changing methods. The algorithm modularity architecture is used as an auxiliary architecture to reduce the instruction cost and increase the computing power. Finally, the hybrid architecture real-time simulation platform was implemented in the Xilinx VC709 board (Xilinx corporation, San Jose, CA, USA), and the verification results show that under the same system scale, the hybrid architecture simulation platform combined with simulation method changing realizes shorter simulation step and complex interactive operation.
An Improved Super-Twisting High-Order Sliding Mode Observer for Sensorless Control of Permanent Magnet Synchronous Motor
Authors: Zhao Yujiao , Yu Haisheng , Wang Shixian
Published: September 2021

This article presents an improved super-twisting high-order sliding mode observer for permanent magnet synchronous motors to achieve high-performance sensorless control. The proposed observer is able to simultaneously estimate rotor position and speed, as well as track parameter disturbances online. Then, according to the back-EMF model, the sensorless observer is further constructed to improve the estimation effect. The estimated rotor position and speed are used to replace the actual values detected by the sensor, and the estimated parameter disturbances are considered as feedback values to compensate the command voltage. In this way, not only is the estimation accuracy improved, but the robustness against uncertainties is also enhanced. Simulation and experimental results show that the proposed observer can effectively track the rotor position and speed and obtain good dynamic and steady-state performance.
Evaluation of Erosion Discharge Characteristics in Inclined Plane Tracking and Erosion Tests on Silicone Rubber under AC and DC Voltages
Authors: Pevtsov Valeria , Jacob Nathan D. , Kordi Behzad
Published: September 2021

This paper investigates partial discharge (PD) characteristics that lead to the erosion of silicone rubber (SR) polymer under AC stress and DC stress of both polarities. The experiments are performed on high temperature vulcanized (HTV) SR material samples. The inclined plane test apparatus, constructed in accordance with IEC 60587 requirements, is employed to produce the surface partial discharges and the resulting accelerated aging of the specimens. Two commercial instruments are used to obtain the PD data. A concurrent analysis of visual observations of discharge and PD data is performed to classify discharges based on the severity of material degradation that each type causes. Three types of PD are identified and characterized using diagrams of charge magnitude versus time and a signal processing technique called time-frequency mapping. Individual pulse waveshapes of each type of discharge are also analyzed. PD pulse waveforms are analyzed according to their amplitude, energy, pulse width, and frequency spectrum. These pulse waveform parameters are evaluated and compared for the eroding discharge pulses under AC and DC voltage stresses. It is found that the stages of material degradation during IPT are related to the variations in discharge magnitude and the location of pulse clusters on the time-frequency maps.
Review of Technologies and Recent Advances in Low-Temperature Sorption Thermal Storage Systems
Authors: Ayaz Hamza , Chinnasamy Veerakumar , Yong Junhyeok , Cho Honghyun
Published: September 2021

Sorption thermochemical storage systems can store thermal energy for the long-term with minimum amount of losses. Their flexibility in working with sustainable energy sources further increases their importance vis-à-vis high levels of pollution from carbon-based energy forms. These storage systems can be utilized for cooling and heating purposes or shifting the peak load. This review provides a basic understanding of the technologies and critical factors involved in the performance of thermal energy storage (TES) systems. It is divided into four sections, namely materials for different sorption storage systems, recent advances in the absorption cycle, system configuration, and some prototypes and systems developed for sorption heat storage systems. Energy storage materials play a vital role in the system design, owing to their thermal and chemical properties. Materials for sorption storage systems are discussed in detail, with a new class of absorption materials, namely ionic liquids. It can be a potential candidate for thermal energy storage due to its substantial thermophysical properties which have not been utilized much. Recent developments in the absorption cycle and integration of the same within the storage systems are summarized. In addition, open and closed systems are discussed in the context of recent reactor designs and their critical issues. Finally, the last section summarizes some prototypes developed for sorption heat storage systems.
The Role of Discounting in Energy Policy Investments
Authors: Maselli Gabriella , Nesticò Antonio
Published: September 2021

For informing future energy policy decisions, it is essential to choose the correct social discount rate (SDR) for ex-ante economic evaluations. Generally, costs and benefits—both economic and environmental—are weighted through a single constant discount rate. This leads to excessive discounting of the present value of cash flows progressively more distant over time. Evaluating energy projects through constant discount rates would mean underestimating their environmental externalities. This study intends to characterize environmental–economic discounting models calibrated for energy investments, distinguishing between intra- and inter-generational projects. In both cases, the idea is to use two discounting rates: an economic rate to assess financial components and an ecological rate to weight environmental effects. For intra-generational projects, the dual discount rates are assumed to be constant over time. For inter-generational projects, the model is time-declining to give greater weight to environmental damages and benefits in the long-term. Our discounting approaches are based on Ramsey’s growth model and Gollier’s ecological discounting model; the latter is expressed as a function of an index capable of describing the performance of a country’s energy systems. With regards to the models we propose, the novelty lies in the calibration of the “environmental quality” parameter. Regarding the model for long-term projects, another innovation concerns the analysis of risk components linked to economic variables; the growth rate of consumption is modelled as a stochastic variable. The defined models were implemented to determine discount rates for both Italy and China. In both cases, the estimated discount rates are lower than those suggested by governments. This means that the use of dual discounting approaches can guide policymakers towards sustainable investment in line with UN climate neutrality objectives.
A Review on the Thermal-Hydraulic Performance and Optimization of Compact Heat Exchangers
Authors: Liao Gaoliang , Li Zhizhou , Zhang Feng , Liu Lijun , E Jiaqiang
Published: September 2021

Heat exchangers play an important role in power, the chemical industry, petroleum, food and many other industrial productions, while compact heat exchangers are more favored in industrial applications due to their high thermal efficiency and small size. This paper summarizes the research status of different types of compact heat exchangers, especially the research results of heat transfer and pressure drop of printed circuit heat exchangers, so that researchers can have an overall understanding of the development of compact heat exchangers and get the required information quickly. In addition, this paper summarizes and analyzes several main working fluids selected in compact heat exchangers, and puts forward some discussions and suggestions on the selection of working fluids. Finally, according to the existing published literature, the performance evaluation indexes of compact heat exchangers are summarized and compared, which is convenient for developers and researchers to better grasp the design direction.
Evaluation of Energy Transition Scenarios in Poland
Authors: Kochanek Ewelina
Published: September 2021

Long-term energy scenarios form the basis of energy policy-making. In practice, the use of energy scenarios for the effective creation of energy policy differs in each country. Therefore, the aim of this study is to present two possible scenarios for the development of the Polish energy sector, resulting from the current national policy and international commitments of Poland. The study examined the development of the energy mix in Poland in the 2040 perspective, in accordance with the strategic document Energy Policy of Poland (PEP 2040). The analysis took into account four diagnostic features: electricity production, electricity price, the share of renewable energy sources (RES) in final energy consumption, and CO2 emission reduction. In addition, the analysis allowed for the presentation of the implications for the Polish economy and society after the application of the diversified variant with nuclear energy and the diversified variant with natural gas. Both scenarios assume too slow development of RES, and the ambivalent attitude of the Polish political elite towards zero-emission energy sources significantly hinders the development of some of its forms (e.g., onshore wind energy). Unfortunately, both the first and second variants entail a large increase in electricity prices, which will affect the entire economy and increase the level of energy poverty among Poles. The study provides strategic insights on the consequences of Poland’s choice of a specific energy transformation scenario. The results may serve as a starting point for understanding Poland’s restraint towards achieving zero emissions and contribute to the discussion of the direction of development of the Polish energy sector.
Fuel Reactor CFD Multiscale Modelling in Syngas-Based Chemical Looping Combustion with Ilmenite
Authors: Sandu Vlad-Cristian , Cormos Ana-Maria , Cormos Calin-Cristian
Published: September 2021

As global power generation is currently relying on fossil fuel-based power plants, more anthropogenic CO2 is being released into the atmosphere. During the transition period to alternative energy sources, carbon capture and storage seems to be a promising solution. Chemical-looping combustion (CLC) is an energy conversion technology designed for combustion of fossil fuel with advantageous carbon capture capabilities. In this work, a 1D computational fluid dynamics (CFD) multiscale model was developed to study the reduction step in a syngas-based CLC system and was validated using literature data (R=0.99). In order to investigate mass transfer effects, flow rate and particle dimension studies were carried out. Sharper mass transfer rates were seen at lower flow rates and smaller granule sizes due to suppression of diffusion limitations. In addition, a 3D CFD particle model was developed to investigate in depth the reduction within an ilmenite particle, with focus on heat transfer effects. Minor differences of 1 K were seen when comparing temperature changes predicted by the two models during the slightly exothermic reduction reaction with syngas.
Social Energy as the Driving Force behind Crowdfunding—Analysis and Classification of Selected Attributes
Authors: Szewczyk Agnieszka , Stempnakowski Zbigniew
Published: September 2021

Crowdfunding has been part of sharing economy for a few decades. Research into crowdfunding usually concerns its relation to sustainable development and corporate social responsibility, influencing investment decisions, psychological, organizational and financial aspects or the success evaluation of individual campaigns or platforms. Recent research includes empirical case studies, e.g., evaluation of the crowdfunding for minor coarse cereal products through evolutionary game analysis, or the impact of crowdfunding on the willingness to visit local festivals. There is, however, no comprehensive cross-sectional approach to crowdfunding attributes that considers data from various categories. The authors aimed to analyze selected attributes of crowdfunding, namely project categories, the number of backers, campaign duration and profitability, and to classify these attributes. A novelty is the use of the term “social energy” in a different sense than previously found in the scientific literature. An original algorithm for analyzing and classifying selected crowdfunding attributes and measuring the relationship between them was also used. The value of the article is also the practical application of its results. The findings have a practical outcome: they can be used by project creators, potential backers, investors and owners of crowdfunding platforms.
Analytical Formulas for Dispersion and Effective Area in Hollow-Core Tube Lattice Fibers
Authors: Rosa Lorenzo , Melli Federico , Vincetti Luca
Published: September 2021

In this work, we propose analytical formulas for the estimation of dispersion properties and effective area of the fundamental mode of hollow-core inhibited coupling fibers with a microstructured cladding composed by a ring of dielectric tubes. The formulas are based on a model which has already been successfully applied to the estimation of confinement loss. The model takes into account the effects of the coupling of the fundamental core mode with the cladding modes in the context of the single-tube approximation. Effective index, group velocity dispersion, and effective area of the fundamental mode are estimated and compared with the results obtained from numerical simulations, by considering ten different fibers. The comparison shows a good accuracy of the proposed formulas, which do not require any tuning of fitting parameters. On the basis of the analysis carried out, a scaling law relating the effective area to the core radius is also given. Finally, the formulas give a good estimation of the same parameters of other Hollow-core inhibited coupling fibers, such as nested, ice-cream, and kagome fibers.