bluuebunny/crossref_metadata_2025 huggingface dataset:
Tunable Martensitic Transformation and Magnetic Properties of Sm-Doped NiMnSn Ferromagnetic Shape Memory Alloys
Authors: Hassan Najam ul , Jelani Mohsan , Shah Ishfaq Ahmad , Rehman Khalil Ur , Khan Abdul Qayyum , Rehman Shania , Jamil Muhammad , Kim Deok-kee , Khan Muhammad Farooq
Published: September 2021

NiMnSn ferromagnetic shape memory alloys exhibit martensitic transformation at low temperatures, restricting their applications. Therefore, this is a key factor in improving the martensitic transformation temperature, which is effectively carried out by proper element doping. In this research, we investigated the martensitic transformation and magnetic properties of Ni43Mn46-x SmxSn11 (x = 0, 1, 2, 3) alloys on the basis of structural and magnetic measurements. X-ray diffraction showed that the crystal structure transforms from the cubic L21 to the orthorhombic martensite and gamma (γ) phases. The reverse martensitic and martensitic transformations were indicated by exothermic and endothermic peaks in differential scanning calorimetry. The martensitic transformation temperature increased considerably with Sm doping and exceeded room temperature for Sm = 3 at. %. The Ni43Mn45SmSn11 alloy exhibited magnetostructural transformation, leading to a large magnetocaloric effect near room temperature. The existence of thermal hysteresis and the metamagnetic behavior of Ni43Mn45SmSn11 confirm the first-order magnetostructural transition. The magnetic entropy change reached 20 J·kg−1·K−1 at 266 K, and the refrigeration capacity reached ~162 J·Kg−1, for Ni43Mn45SmSn11 under a magnetic field variation of 0–5 T.
Seismic Envelopes of Coda Decay for Q-coda Attenuation Studies of the Gargano Promontory (Southern Italy) and Surrounding Regions
Authors: Filippucci Marilena , Lucente Salvatore , de Lorenzo Salvatore , Del Pezzo Edoardo , Prosser Giacomo , Tallarico Andrea
Published: September 2021

Here, we describe the dataset of seismic envelopes used to study the S-wave Q-coda attenuation quality factor Qc of the Gargano Promontory (Southern Italy). With this dataset, we investigated the crustal seismic attenuation by the Qc parameter. We collected this dataset starting from two different earthquake catalogues: the first regarding the period from April 2013 to July 2014; the second regarding the period from July 2015 to August 2018. Visual inspection of the envelopes was carried out on recordings filtered with a Butterworth two-poles filter with central frequency fc = 6 Hz. The obtained seismic envelopes of coda decay can be linearly fitted in a bilogarithmic diagram in order to obtain a series of single source-receiver measures of Qc for each seismogram component at different frequency fc. The analysis of the trend Qc(fc) gives important insights into the heterogeneity and the anelasticity of the sampled Earth medium.
Hyperuricemia and Progression of Chronic Kidney Disease: A Review from Physiology and Pathogenesis to the Role of Urate-Lowering Therapy
Authors: Lee Tao Han , Chen Jia-Jin , Wu Chao-Yi , Yang Chih-Wei , Yang Huang-Yu
Published: September 2021

The relationship between hyperuricemia, gout, and renal disease has been investigated for several years. From the beginning, kidney disease has been considered a complication of gout; however, the viewpoints changed, claiming that hypertension and elevated uric acid (UA) levels are caused by decreased urate excretion in patients with renal impairment. To date, several examples of evidence support the role of hyperuricemia in cardiovascular or renal diseases. Several mechanisms have been identified that explain the relationship between hyperuricemia and chronic kidney disease, including the crystal effect, renin–angiotensin–aldosterone system activation, nitric oxide synthesis inhibition, and intracellular oxidative stress stimulation, and urate-lowering therapy (ULT) has been proven to reduce renal disease progression in the past few years. In this comprehensive review, the source and physiology of UA are introduced, and the mechanisms that explain the reciprocal relationship between hyperuricemia and kidney disease are reviewed. Lastly, current evidence supporting the use of ULT to postpone renal disease progression in patients with hyperuricemia and gout are summarized.
Granger Causality among Graphs and Application to Functional Brain Connectivity in Autism Spectrum Disorder
Authors: Ribeiro Adèle Helena , Vidal Maciel Calebe , Sato João Ricardo , Fujita André
Published: September 2021

Graphs/networks have become a powerful analytical approach for data modeling. Besides, with the advances in sensor technology, dynamic time-evolving data have become more common. In this context, one point of interest is a better understanding of the information flow within and between networks. Thus, we aim to infer Granger causality (G-causality) between networks’ time series. In this case, the straightforward application of the well-established vector autoregressive model is not feasible. Consequently, we require a theoretical framework for modeling time-varying graphs. One possibility would be to consider a mathematical graph model with time-varying parameters (assumed to be random variables) that generates the network. Suppose we identify G-causality between the graph models’ parameters. In that case, we could use it to define a G-causality between graphs. Here, we show that even if the model is unknown, the spectral radius is a reasonable estimate of some random graph model parameters. We illustrate our proposal’s application to study the relationship between brain hemispheres of controls and children diagnosed with Autism Spectrum Disorder (ASD). We show that the G-causality intensity from the brain’s right to the left hemisphere is different between ASD and controls.
Trajectory Planning of Robot Manipulator Based on RBF Neural Network
Authors: Song Qisong , Li Shaobo , Bai Qiang , Yang Jing , Zhang Ansi , Zhang Xingxing , Zhe Longxuan
Published: September 2021

Robot manipulator trajectory planning is one of the core robot technologies, and the design of controllers can improve the trajectory accuracy of manipulators. However, most of the controllers designed at this stage have not been able to effectively solve the nonlinearity and uncertainty problems of the high degree of freedom manipulators. In order to overcome these problems and improve the trajectory performance of the high degree of freedom manipulators, a manipulator trajectory planning method based on a radial basis function (RBF) neural network is proposed in this work. Firstly, a 6-DOF robot experimental platform was designed and built. Secondly, the overall manipulator trajectory planning framework was designed, which included manipulator kinematics and dynamics and a quintic polynomial interpolation algorithm. Then, an adaptive robust controller based on an RBF neural network was designed to deal with the nonlinearity and uncertainty problems, and Lyapunov theory was used to ensure the stability of the manipulator control system and the convergence of the tracking error. Finally, to test the method, a simulation and experiment were carried out. The simulation results showed that the proposed method improved the response and tracking performance to a certain extent, reduced the adjustment time and chattering, and ensured the smooth operation of the manipulator in the course of trajectory planning. The experimental results verified the effectiveness and feasibility of the method proposed in this paper.
A Study of Maintenance-Related Education in Swedish Engineering Programs
Authors: Kans Mirka
Published: September 2021

Engineers of today require a holistic understanding of the lifecycle of products and processes, from conceptualization to operations. Maintenance and reliability are areas receiving increased attention due to the contribution to sustainable industry practices. The related literature describes ways to strengthen the education with respect to curricula and teaching, but studies on the extent and content of maintenance-related education in engineering programs are lacking. The purpose of this study is to describe the maintenance-related education content in Swedish engineering programs. The main objects of study are the curricula and courses of engineering programs in Sweden. In total, 123 Bachelor of Engineering and 119 Master of Engineering programs were studied, as well as 36 maintenance-related courses. It was found that 12% of the engineering programs include one or more maintenance-related course, either mandatory or elective. On the Master of Engineering level, only 4% of the programs include mandatory maintenance-related courses. The corresponding number for Bachelor of Engineering programs is 15%. The courses are typically of 6–7.5 credits, but as low as under one credit worth of maintenance-related content is seen, as well as two specialized programs offering up to 60 credits. Of the 36 courses, 20 have a distinct maintenance focus, 2 are degree thesis courses, and 2 are within reliability engineering, while the rest have a focus in other areas. The lack of maintenance-related education makes future engineers less prepared to make good decisions and judgments that might affect the operational phase of the product or system.
Implementation of a Surgery Congress for Medical Students to Learn Transversal Competences. A Case of Student-Led Teaching Activity
Authors: Herrero de la Parte Borja , Santaolalla-Sánchez María , Santaolalla-Sánchez Francisco Javier , García-Alonso Ignacio , Santaolalla Francisco , Sánchez del Rey Ana
Published: September 2021

Background: A dynamic training approach close to clinical work and research is highly requested by health sciences students. The aim of this paper is to present the organizational model of a student-promoted and student-managed surgical congress that encourages the acquisition of transversal competencies among the students in charge of the organization of the Congress. Methods: A two-day surgical congress for medical students organized by themselves was held. Each day comprised two separate sections corresponding to different surgical specialties; sections included three types of activities: conferences, round tables with guest professors, and practical workshops. Once the Congress had finished, an online survey was carried out to evaluate 10 items scored from 1 to 4. To assess the acquisition of transversal competences among the students organizing the congress, three evaluations were carried out by the professor involved in the organization of the congress. Results: The congress had great acceptance among the students, filling 150 available places with an attendance rate of 100%. The survey showed a high assessment of the subjects (3.48/4), conferences (3.48/4) and workshops (3.27/4). Evaluation of the round tables was significantly lower (2/4). A total of 99% considered the congress to have been useful in its formation process and 100% would recommend it. The grade of transversal competences among the students organizing the congress showed a significant increase between the first and the third evaluation, being between 1.24 and 7.25 times higher. Conclusions: the student-led student surgical congress is a well-evaluated activity for medical students, and promotes, among its organizers, the acquisition of transversal competences.
Design of Composite Disturbance Observer and Continuous Terminal Sliding Mode Control for Piezoelectric Nanopositioning Stage
Authors: Qiao Pengyu , Yang Jun , Dai Chen , Xiao Xi
Published: September 2021

The nonlinearities of piezoelectric actuators and external disturbances of the piezoelectric nanopositioning stage impose great, undesirable influences on the positioning accuracy of nanopositioning stage systems. This paper considers nonlinearities and external disturbances as a lumped disturbance and designs a composite control strategy for the piezoelectric nanopositioning stage to realize ultra-high precision motion control. The proposed strategy contains a composite disturbance observer and a continuous terminal sliding mode controller. The composite disturbance observer can estimate both periodic and aperiodic disturbances so that the composite control strategy can deal with the disturbances with high accuracy. Meanwhile, the continuous terminal sliding mode control is employed to eliminate the chattering phenomenon and speed up the convergence rate. The simulation and experiment results show that the composite control strategy achieves accurate estimation of different forms of disturbances and excellent tracking performance.
Effect of the APD Receiver’s Tilted Angle on Channel Capacity for Underwater Wireless Optical Communications
Authors: Ju Meiyan , Shi Hongqiang , Li Yueheng , Huang Ping , Tan Guoping
Published: September 2021

This paper focuses on investigating the effect of the receiver’s tilted angle on the channel capacity of an underwater wireless optical communication (UWOC) system, in which an avalanche photodiode (APD) detector is adopted as the receiver. Under the non-negativity, peak power, and average power constraints, the lower bounds on the capacity of UWOC are derived in detail according to different average-to-peak power ratios. With modeling achieving the maximum of the lower bounds of the capacity as an optimization object, we prove that the proposed optimization issue is in fact a simple convex optimization about the tilted angle of the APD receiver, and then present related theoretical solution for it. Both theoretical analysis and simulation results show that by appropriately tilting the receiver, we can significantly enhance the final capacity performance of the UWOC with APD receiver.
Fault-Tolerant Tracking Control for a Descriptor System under an Unknown Input Disturbances
Authors: Kukurowski Norbert , Pazera Marcin , Witczak Marcin
Published: September 2021

The paper proposes a fault-tolerant tracking control scheme based on a robust observer for a descriptor system. Thus, it is assumed that the described system can be simultaneously occupied by an unknown input disturbance, along with an actuator and sensor faults. Additionally, it is natural to assume that the unknown input disturbance cannot be estimated, which makes the control process more difficult. Moreover, the proposed descriptor system is also occupied by external disturbances. Thus, the robust stability of the proposed control and estimation scheme was guaranteed by using H∞ performance. Consequently, the DC servo-motor laboratory system was used to confirm the correctness and effectiveness of the proposed fault-tolerant tracking control scheme.
Mixed-Carrier Communication for Technology Division Multiplexing
Authors: Hussein Ahmed F. , Saha Dola , Elgala Hany
Published: September 2021

Recently, research on sixth-generation (6G) networks has gained significant interest. 6G is expected to enable a wide-range of applications that fifth-generation (5G) networks will not be able to serve reliably, such as tactile Internet. Additionally, 6G is expected to offer Terabits per second (Tbps) data rates, 10 times lower latency, and near 100% coverage, compared to 5G. Thus, 6G is expected to expand across all available spectrums including terahertz (THz) and optical frequency bands. In this manuscript, mixed-carrier communication (MCC) is investigated as a novel physical layer (PHY) design for 6G networks. The proposed MCC version in this study is based on visible light communication (VLC). MCC enables a unified transmission PHY design to connect devices with different complexities, simultaneously. The design trade-offs and the required signal-to-noise ratio (SNR) per individual modulation schemes embedded within MCC are investigated. The complexity analysis shows that a conventional optical OFDM receiver can capture the high-speed bit-stream embedded within MCC. For a forward error correction (FEC) bit-error-rate (BER) threshold of 3.8×10−3, MCC is optimized to maximize the spectral efficiency by embedding 2-beacon phase-shift keying (2-BnPSK) within an MCC envelope on top of 12 bits per beacon position modulation (BPM) symbol.
Testing the Scalability of the HS-AUTOFIT Tool in a High-Performance Computing Environment
Authors: Di Modica Giuseppe , Evangelisti Luca , Foschini Luca , Maris Assimo , Melandri Sonia
Published: September 2021

In the last years, the development of broadband chirped-pulse Fourier transform microwave spectrometers has revolutionized the field of rotational spectroscopy. Currently, it is possible to experimentally obtain a large quantity of spectra that would be difficult to analyze manually due to two main reasons. First, recent instruments allow obtaining a considerable amount of data in very short times, and second, it is possible to analyze complex mixtures of molecules that all contribute to the density of the spectra. AUTOFIT is a spectral assignment software application that was developed in 2013 to support and facilitate the analysis. Notwithstanding the benefits AUTOFIT brings in terms of automation of the analysis of the accumulated data, it still does not guarantee a good performance in terms of execution time because it leverages the computing power of a single computing machine. To cater to this requirement, we developed a parallel version of AUTOFIT, called HS-AUTOFIT, capable of running on high-performance computing (HPC) clusters to shorten the time to explore and analyze spectral big data. In this paper, we report some tests conducted on a real HPC cluster aimed at providing a quantitative assessment of HS-AUTOFIT’s scaling capabilities in a multi-node computing context. The collected results demonstrate the benefits of the proposed approach in terms of a significant reduction in computing time.
Automatic Estimation of Age Distributions from the First Ottoman Empire Population Register Series by Using Deep Learning
Authors: Can Yekta Said , Kabadayı M. Erdem
Published: September 2021

Recently, an increasing number of studies have applied deep learning algorithms for extracting information from handwritten historical documents. In order to accomplish that, documents must be divided into smaller parts. Page and line segmentation are vital stages in the Handwritten Text Recognition systems; it directly affects the character segmentation stage, which in turn determines the recognition success. In this study, we first applied deep learning-based layout analysis techniques to detect individuals in the first Ottoman population register series collected between the 1840s and the 1860s. Then, we employed horizontal projection profile-based line segmentation to the demographic information of these detected individuals in these registers. We further trained a CNN model to recognize automatically detected ages of individuals and estimated age distributions of people from these historical documents. Extracting age information from these historical registers is significant because it has enormous potential to revolutionize historical demography of around 20 successor states of the Ottoman Empire or countries of today. We achieved approximately 60% digit accuracy for recognizing the numbers in these registers and estimated the age distribution with Root Mean Square Error 23.61.
Influence of DC Electric Field on the Propane-Air Diffusion Flames and NOx Formation
Authors: Kim Sang-Min , Han Kyeong-Soo , Baek Seung-Wook
Published: September 2021

The aim of this research is to investigate the effects of a direct current (DC) electric field on the combustion behavior of a co-flow propane diffusion flame. The flame length and NOx emission were observed and measured. The electric field enhances the combustion process of propane diffusion flame by causing the movement of ions and molecules in the flame, resulting in a change in the shape of the flame. The flame heights decrease with an increase in the applied voltage and polarity, a more dominant effect to be observed with a positive DC electric field. However, for the applied negative polarity, the inner-cone of the propane diffusion flame is shifted by the electric field. Drastic reduction in the NOx emission is observed with an increase in the applied DC voltage and polarity. In the existing system, the reduction percentage of NOx is within the range of 55 to 78%.
An Ultra-Fast Power Prediction Method Based on Simplified LSSVM Hyperparameters Optimization for PV Power Smoothing
Authors: Zhao Zhenxing , Chen Kaijie , Chen Ying , Dai Yuxing , Liu Zeng , Zhao Kuiyin , Wang Huan , Peng Zishun
Published: September 2021

With existing power prediction algorithms, it is difficult to satisfy the requirements for prediction accuracy and time when PV output power fluctuates sharply within seconds, so this paper proposes a high-precision and ultra-fast PV power prediction algorithm. Firstly, in order to shorten the optimization time and improve the optimization accuracy, the single-iteration Gray Wolf Optimization (SiGWO) method is used to simplify the iteration process of the hyperparameters of Least Squares Support Vector Machine (LSSVM), and then the hybrid local search algorithm composed of Iterative Local Search (ILS) and Self-adaptive Differential Evolution (SaDE) is used to improve the accuracy of hyperparameters, so as to achieve high-precision and ultra-fast PV power prediction. The power prediction model is established, and the proposed algorithm is applied in a test experiment which can complete the power prediction within 3 s, and the RMSE is only 0.44%. Finally, combined with the PV-storage advanced smoothing control strategy, it is verified that the performance of the proposed algorithm can satisfy the system’s requirements for prediction accuracy and time under the condition of power mutation in a PV power generation system.
A New Arrangement of Active Coils for Wireless Charging of UAV
Authors: He Zhengwang , Li Zhiyong , Wang Ruoyue , Fan Ying , Xu Minqian
Published: September 2021

This paper presents the design and optimization of a wireless power transfer (WPT) charging system based on magnetically coupled resonant technology, applied to an Unmanned Aerial Vehicle (UAV). In this paper, a charging system, including dual active transmitter coils and a single receiver coil, is proposed. The dual transmitting coils adopt a coaxial structure with different radii. This structure simplifies the calculation of the complex mutual inductance between the coils to a function of mutual inductance only related to the value of the radial misalignment. Aiming toward a constant charging power, the optimal transmission efficiency of electric energy is achieved by controlling the input voltages of the active coils, which are solved via a set of equations defined as Lagrange multipliers. The simulation results of the 570 V and 85,000 Hz system verified the validity of the proposed wireless UAV charging scheme.
Numerical Simulation of Heat Transport Problems in Porous Media Coupled with Water Flow Using the Network Method
Authors: Jiménez-Valera José Antonio , García-Ros Gonzalo , Alhama Iván
Published: September 2021

In the present work, a network model for the numerical resolution of the heat transport problem in porous media coupled with a water flow is presented. Starting from the governing equations, both for 1D and 2D geometries, an equivalent electrical circuit is obtained after their spatial discretization, so that each term or addend of the differential equation is represented by an electrical device: voltage source, capacitor, resistor or voltage-controlled current source. To make this possible, it is necessary to establish an analogy between the real physical variables of the problem and the electrical ones, that is: temperature of the medium and voltage at the nodes of the network model. The resolution of the electrical circuit, by means of the different circuit resolution codes available today, provides, in a fast, simple and precise way, the exact solution of the temperature field in the medium, which is usually represented by abaci with temperature-depth profiles. At the end of the article, a series of applications allow, on the one hand, to verify the precision of the numerical tool by comparison with existing analytical solutions and, on the other, to show the power of calculation and representation of solutions of the network models presented, both for problems in 1D domains, typical of scenarios with vertical flows, and for 2D scenarios with regional flow.
Nonlinear Controller for the Set-Point Regulation of a Buck Converter System
Authors: Campos-Mercado Eduardo , Mendoza-Santos Edwin Fernando , Torres-Muñoz Jorge Antonio , Román-Hernández Edwin , Moreno-Oliva Víctor Iván , Hernández-Escobedo Quetzalcoatl , Perea-Moreno Alberto-Jesus
Published: September 2021

In this paper, we present a nonlinear PID controller based on saturation functions with variable parameters in order to regulate the output voltage of a buck converter in the presence of changes in the input voltage. The main feature of the proposed controller is to bound the control input with a variable parameter to avoid the windup effect generated by the combination of the integral control action and some operation conditions. The main advantages of the proposed nonlinear PID controller are its low computing cost and the simple tuning task to implement the control strategy in an embedded system. The acceptable behavior of the closed-loop system is presented through the simulation and experimental results.
Enhanced Oil Recovery by Hydrophilic Silica Nanofluid: Experimental Evaluation of the Impact of Parameters and Mechanisms on Recovery Potential
Authors: Chandio Tariq Ali , Manan Muhammad A. , Memon Khalil Rehman , Abbas Ghulam , Abbasi Ghazanfer Raza
Published: September 2021

Nanofluids as an EOR technique are reported to enhance oil recoveries. Among all the nanomaterial silica with promising lab results, economic and environmental acceptability are an ideal material for future applications. Despite the potential to enhance recoveries, understanding the two-fold impact of parameters such as concentration, salinity, stability, injection rate, and irreproducibility of results has arisen ambiguities that have delayed field applications. This integrated study is conducted to ascertain two-fold impacts of concentration and salinity on recovery and stability and evaluates corresponding changes in the recovery mechanism with variance in the parameters. Initially, silica nanofluids’ recovery potential was evaluated by tertiary flooding at different concentrations (0.02, 0.05, 0.07, 0.1) wt. % at 20,000 ppm salinity. The optimum concentration of 0.05 wt. % with the highest potential in terms of recovery, wettability change, and IFT reduction was selected. Then nano-flooding was carried out at higher salinities at a nanomaterial concentration of 0.05 wt. %. For the mechanism’s evaluation, the contact angle, IFT and porosity reduction, along with differential profile changes were analyzed. The recovery potential was found at its highest for 0.05 wt. %, which reduced when concentrations were further increased as the recovery mechanisms changed and compromised stability. Whereas salinity also had a two-fold impact with salinity at 30,000 ppm resulting in lower recovery, higher salinity destabilized the solution but enhanced recoveries by enhancing macroscopic mechanisms of pore throat plugging.
Optimization of a Thermomagnetic Heat Engine for Harvesting Low Grade Thermal Energy
Authors: Zeeshan  , Mehmood Muhammad Uzair , Cho Sungbo
Published: September 2021

Thermomagnetic energy harvesters are one form of technology that can be effectively used to extract energy from low grade heat sources, without causing damage to the environment. In this study, we investigated the output performance of our previously designed thermomagnetic heat engine, which was developed to extract thermal energy by exploiting the magnetocaloric effect of gadolinium. The proposed heat engine uses water as the heat transfer fluid, with heat sources at a temperature in the range 20–65 °C. Although this method turned out to be a promising solution to extract thermal energy, the amount of energy extracted through this geometry of thermomagnetic engine was limited and depends on the interaction between magnetic flux and magnetocaloric material. Therefore, in this paper we carry out an in-depth analysis of the designed thermomagnetic heat engine with an integrated approach of numerical simulation and experimental validation. The computational model improved recognition of the critical component to developing an optimized model of the thermomagnetic heat engine. Based on the simulation result, a new working model was developed that showed a significant improvement in the rpm and axial torque generation. The results indicate that the peak RPM and torque of the engine are improved by 34.3% and 32.2%, respectively.
Feasibility Evaluation on Elimination of DC Filters for Line-Commutated Converter-Based High-Voltage Direct Current Projects in New Situations
Authors: Li Xiaodong , Xu Zheng
Published: September 2021

The line-commutated converter (LCC)-based high voltage direct current (HVDC) technology has been widely applied on long-distance and bulk-capacity power transmission occasions. Due to the terrible interferences in the vicinity of communication lines, DC filters (DCFs) are always installed to mitigate the interferences within acceptable levels for almost all in-service overhead line transmission LCC-HVDC schemes. With the rapid development of the communication technology, however, the anti-interference capability of the telephone system has been remarkably improved. Thus, the original purpose of employing DCFs has been virtually absent, and the necessity of the DCFs shall be re-evaluated in sufficient depth not only for new LCC-HVDC projects, but also in the case of refurbishment of older projects. To demonstrate this constructive topic, this paper carries out a commercial ±800 kV/8000 MW LCC-HVDC project as an illustrative example to analyze and discuss those crucial aspects, which may influence the LCC-HVDC stable operation and reliability after removing the DCFs. Then, the paper studies the harmonic voltage/current stresses of the DC equipment, the DC loop low-order harmonic resonances, and the overvoltage under the switching surge and lightning stroke. Finally, it is concluded that the DCF elimination mainly affects the harmonic steady-state stresses of the DC equipment, but has little influence on the transient stresses. For the refurbishment of older projects, the evaluation on the cost between the DCFs’ maintenance cost and the equipment modification is needed for the DCFs’ elimination. For new LCC-HVDC projects, the DCFs’ elimination or at least simplification may be a more economical and attractive alternative, thereby reducing the footprint and cost.
CFD Simulation of a 3D Solar Chimney Integrated with an Axial Turbine for Power Generation
Authors: Danook Suad Hassan , AL-bonsrulah Hussein A. Z. , Hashim Ishak , Veeman Dhinakaran
Published: September 2021

The solar chimney is one of the uninvestigated areas in the possible selection in the field of renewable solar energy utilization. CFD can be demonstrated as a useful tool of figure confidence in the design and employment of a solar chimney. A realistic numerical model for a solar-based updraft power plant for power generation was established through this research work. Iraqi weather in Kirkuk, northern Iraq was considered for this case study. A three-dimensional (3D) simulation of the main geometric dimensions of the Spanish, Manzanares model integrated with a real turbine was performed using computational fluid dynamics (CFD). The turbulent model of RNG k-e, the nongrey discrete coordinate (DO) radiation model, and the solar raytracing algorithm were used. It was observed that the air velocity below the turbine was graded according to the seasons of the year and was at its maximum in July with 18.28 m/s due to the high ambient temperature, and the lowest value was recorded in January with 8.64 m/s. The overall average daily and monthly energy production values for the Kirkuk system were higher than those of the Kubang system, with values of 310 kWh/day and 9314 kWh/month, respectively, for the Kirkuk system, and 246 kWh/day and 7398 kWh/month, respectively, for the Kubang system. The simulation results showed that the electricity generation from the Kirkuk city power plant varied seasonally to be at its maximum value of 14,424 kWh/month in July. This research work will help to determine the possibility of producing electricity in this Kirkuk city, which would then contribute in a great way to reduce the cash spent on electricity.
The Impact of Psychological Distance on Judging Satisfaction with Nuclear Energy Policy via Knowledge Calibration and an Integrated Causal Path Model
Authors: Kim Byoung Joon , Kim Seoyong
Published: September 2021

This study investigated how, through knowledge calibration and a causal path model, psychological distance can explain the level of satisfaction with nuclear energy policy. The investigation used multiple regression analysis and path analysis to explore relationships among variables. Data from 1056 adults revealed that more knowledge-calibrated individuals have more positive attitudes toward nuclear energy policy. In addition, the psychological distance influences policy satisfaction by mediation of perceived risk of nuclear energy. This study aimed to increase the understanding of the dynamic of satisfaction with and acceptance of nuclear energy policy among stakeholders. Thus, based on the construal level theory, the study addressed the importance of knowledge and psychological distance in explaining variation in satisfaction and acceptance about nuclear policy.
The Impact of Electricity Consumption Profile in Underground Mines to Cooperate with RES
Authors: Kaczmarzewski Sylwester , Olczak Piotr , Sołtysik Maciej
Published: September 2021

In Poland, a dynamic increase in the share of renewable energy sources in the national energy mix has been observed in recent years. Until now, these were mainly installations used for the needs of single-family houses and large-scale installations used on the RES auction market. However, due to the fact that the carbon footprint of the offered products is taken into account, this aspect is becoming more and more important. The carbon footprint can be offset by, among others, by covering the energy needs of the industrial plant by its own renewable energy sources. The article analyzes four sample electricity demand profiles of production plants operating in the mining industry, mainly located in Upper Silesia. Using statistical methods, the fitting of potential photovoltaic sources production profiles to the electricity consumption profiles in the analyzed case studies was checked. The analysis was carried out for each hour of the day and for the profiles weighted by the electricity price from the Polish Power Exchange on the Day-Ahead Market, because matching profiles at different hours has a different monetary value and, as a result, a different impact on operation costs. The highest correlation coefficient between electricity consumption and insolation on an annual basis was −0.29 in the Spearman rho-statistic for the case of M1 enterprise. On the other hand, the highest value at the level of 0.48 was achieved by the Pearson r-correlation coefficient determined on a monthly basis between the monetary value of electricity consumed and insolation in June for the M2 enterprise.
Assessment of Social Acceptance for Autonomous Vehicles in Southeastern Poland
Authors: Dudziak Agnieszka , Stoma Monika , Kuranc Andrzej , Caban Jacek
Published: September 2021

New technologies reaching out for meeting the needs of an aging population in developed countries have given rise to the development and gradual implementation of the concept of an autonomous vehicle (AV) and have even made it a necessity and an important business paradigm. However, in parallel, there is a discussion about consumer preferences and the willingness to pay for new car technologies and intelligent vehicle options. The main aim of the study was to analyze the impact of selected factors on the perception of the future of autonomous cars by respondents from the area of Southeastern Poland in terms of a comparison with traditional cars, with particular emphasis on the advantages and disadvantages of this concept. The research presented in this study was conducted in 2019 among a group of 579 respondents. Data analysis made it possible to identify potential advantages and disadvantages of the concept of introducing autonomous cars. A positive result of the survey is that 68% of respondents stated that AV will be gradually introduced to our market, which confirms the high acceptance of this technology by Poles. The obtained research results may be valuable information for governmental and local authorities, but also for car manufacturers and their future users. It is an important issue in the area of shaping the strategy of actions concerning further directions of development on the automotive market.
ERβ in Triple-Negative Breast Cancer: Emerging Concepts and Therapeutic Possibilities
Authors: Monaco Alessandra , Licitra Fabrizio , Di Gisi Martina , Galasso Giovanni , Di Donato Marzia , Giovannelli Pia , Migliaccio Antimo , Castoria Gabriella
Published: September 2021

Despite the improvements in diagnostic and therapeutic approaches, breast cancer still remains one of the world’s leading causes of death among women. Particularly, triple negative breast cancer (TNBC) is characterized by aggressiveness, metastatic spreading, drug resistance and a very high percentage of death in patients. Nowadays, identification of new targets in TNBC appears very compelling. TNBC are considered negative for the estrogen receptor alpha (ERα) expression. Nevertheless, they often express ERβ and its variants. As such, this TNBC subtype still responds to estrogens. While the ERβ1 variant seems to act as a tumor-suppressor, the two variants ERβ2 and 5 exhibit pro-oncogenic activities in TNBC. Thus, ERβ1 activation might be used to limit the growth and spreading as well as to increase the drug sensitivity of TNBC. In contrast, the pro-oncogenic properties of ERβ2 and ERβ5 suggest the possible development and clinical use of specific antagonists in TNBC treatment. Furthermore, the role of ERβ might be regarded in the context of the androgen receptor (AR) expression, which represents another key marker in TNBC. The relationship between AR and ERβ as well as the ability to modulate the receptor-mediated effects through agonists/antagonists represent a challenge to develop more appropriate therapies in clinical management of TNBC patients. In this review, we will discuss the most recent data in the field. Therapeutic implications of these findings are also presented in the light of the discovery of specific ERβ modulators.
Experimental Examination of Vegetative Propagation Methods of Nothofagus antarctica (G. Forst.) Oerst. for Restoration of Fire-Damaged Forest in Torres del Paine National Park, Chile
Authors: Cafourek Josef , Maděra Petr , Střítecký Josef , Adolt Radim , Smola Martin
Published: September 2021

Nothofagus antarctica (Antarctic beech) is one of the main woody plants in the temperate deciduous forests and anti-boreal forests of the southern hemisphere. Since colonization of the Andean-Patagonian region by European settlers, however, stands of this species have been severely affected by fires caused by human activities, considerably reducing their area. To restore these forests to their area occupied before the fires, it is necessary to use artificial regeneration, relying on production of transplants in forest nurseries. Due to the low capacity for seed propagation, we focus on possibilities of producing seedlings by vegetative propagation. In a trial, we collected cuttings during three sets of dates, and attempted to root them using three combinations of substrate and ten combinations of stimulators. Using the most favorable combination of collection period, substrate and stimulator tested resulted in rooting of 23% of the cuttings, which exceeds the documented germination rates for this species.
Virtual Truffle Hunting—A New Method of Burgundy Truffle (Tuber aestivum Vittad.) Site Typing
Authors: Rosa-Gruszecka Aleksandra , Hilszczańska Dorota , Pacioni Giovanni
Published: September 2021

The aim of this study was to enable searches for truffles (Tuber spp.), particularly the Burgundy truffle (T. aestivum Vittad.), to be carried out in forests based on a method that has been constantly developed since 2007 by the Forest Research Institute. The method is termed “Virtual Truffle Hunting” and it takes 12 parameters into account: bedrock, soil pH, Ca+ and CaCO3 content in soil, C/N ratio, soil structure, altitude of terrain, type of forest site, forest structure, the Burgundy truffle host trees, and the presence of particular species including orchids and insects. A simple “Virtual Truffle Hunting” software has also been developed, which makes the use of the method easy, fast, and effective. This method is to ascertain the truffle potential for all areas in which digital maps are not available. In 2015, the method was tested in 20 sites, representing forests in 5 Polish macroregions. Hunting for hypogeous fungi was conducted from June to October with the help of trained dogs. Thanks to this method, 14 new truffle sites were found. The knowledge of environmental conditions conducive to the Burgundy truffle growth enabled us to form an effective tool in order to identify new sites of truffle presence.
Carboxymethyl Cellulose Enhanced Production of Cellulose Nanofibrils
Authors: Kim Yunsang , McCoy Lauren T. , Feit Corbin , Mubarak Shuaib A. , Sharma Suraj , Minko Sergiy
Published: September 2021

Cellulose nanofibrils (CNF) were produced by high-pressure homogenization from kraft pulp in the presence of carboxymethyl cellulose (CMC) of varying molecular weights. CNF pretreated with 250 kD CMC exhibited the maximum specific surface area (SSA) of 641 m2/g, which is comparable to that of CNF pretreated by 2,2,6,6-tetramethyl-piperidinyl-1-oxyl (TEMPO)-meditated oxidation with a high degree of fibrillation. Rheological and microscopic analyses also indicated a high level of fibrillation for the CMC-pretreated CNF. In contrast, the reference CNF without the CMC pretreatment showed a lower level of fibrillation, which was reflected in decreased viscosity and the reduction of SSA by a factor of 19. With the high-degree fibrillation and low toxicity, the CMC pretreatment is a promising method for the production of high-quality CNF in an environmentally friendly way.
Investigation of Non-Linear Rheological Characteristics of Barite-Free Drilling Fluids
Authors: Leusheva Ekaterina , Brovkina Nataliia , Morenov Valentin
Published: September 2021

Drilling fluids play an important role in the construction of oil and gas wells. Furthermore, drilling of oil and gas wells at offshore fields is an even more complex task that requires application of specialized drilling muds, which are non-Newtonian and complex fluids. With regard to fluid properties, it is necessary to manage the equivalent circulation density because its high values can lead to fracture in the formation, loss of circulation and wellbore instability. Thus, rheology of the used drilling mud has a significant impact on the equivalent circulation density. The aim of the present research is to develop compositions of drilling muds with a low solids load based on salts of formate acid and improve their rheological parameters for wells with a narrow drilling fluid density range. Partially hydrolyzed polyacrylamide of different molecular weights was proposed as a replacement for hydrolized polyacrylamide. The experiment was conducted on a Fann rotary viscometer. The article presents experimentally obtained data of indicators such as plastic viscosity, yield point, nonlinearity index and consistency coefficient. Experimental data were analyzed by the method of approximation. Analysis is performed in order to determine the most suitable rheological model, which describes the investigated fluids’ flow with the least error.
Non-Targeted LC-MS Metabolomics Approach towards an Authentication of the Geographical Origin of Grain Maize (Zea mays L.) Samples
Authors: Schütz David , Achten Elisabeth , Creydt Marina , Riedl Janet , Fischer Markus
Published: September 2021

Safety along the food and feed supply chain is an emerging topic and closely linked to the ability to analytical trace the geographical origin of food or feed. In this study, ultra-performance liquid chromatography coupled with electrospray ionization quadrupole-time-of-flight mass spectrometry was used to trace back the geographical origin of 151 grain maize (Zea mays L.) samples from seven countries using a high resolution non-targeted metabolomics approach. Multivariate data analysis and univariate statistics were used to identify promising marker features related to geographical origin. Classification using only 20 selected markers with the Random Forest algorithm led to 90.5% correctly classified samples with 100 times repeated 10-fold cross-validation. The selected markers were assigned to the class of triglycerides, diglycerides and phospholipids. The marker set was further evaluated for its ability to separate between one sample class and the rest of the dataset, yielding accuracies above 89%. This demonstrates the high potential of the non-polar metabolome to authenticate the geographic origin of grain maize samples. Furthermore, this suggests that focusing on only a few lipids with high potential for grain maize authentication could be a promising approach for later transfer of the method to routine analysis.
Effect of Storage Conditions on the Quality of Arbequina Extra Virgin Olive Oil and the Impact on the Composition of Flavor-Related Compounds (Phenols and Volatiles)
Authors: Caipo Leeanny , Sandoval Ana , Sepúlveda Betsabet , Fuentes Edwar , Valenzuela Rodrigo , Metherel Adam H. , Romero Nalda
Published: September 2021

Commercialization of extra virgin olive oil (EVOO) requires a best before date recommended at up to 24 months after bottling, stored under specific conditions. Thus, it is expected that the product retains its chemical properties and preserves its ‘extra virgin’ category. However, inadequate storage conditions could alter the properties of EVOO. In this study, Arbequina EVOO was exposed to five storage conditions for up to one year to study the effects on the quality of the oil and the compounds responsible for flavor. Every 15 or 30 days, samples from each storage condition were analyzed, determining physicochemical parameters, the profiles of phenols, volatile compounds, α-tocopherol, and antioxidant capacity. Principal component analysis was utilized to better elucidate the relationships between the composition of EVOOs and the storage conditions. EVOOs stored at −23 and 23 °C in darkness and 23 °C with light, differed from the oils stored at 30 and 40 °C in darkness. The former was associated with a higher quantity of non-oxidized phenolic compounds and the latter with higher elenolic acid, oxidized oleuropein, and ligstroside derivatives, which also increased with storage time. (E)-2-nonenal (detected at trace levels in fresh oil) was selected as a marker of the degradation of Arbequina EVOO quality over time, with significant linear regressions identified for the storage conditions at 30 and 40 °C. Therefore, early oxidation in EVOO could be monitored by measuring (E)-2-nonenal levels.