bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear and Nonlinear Normal Interface Stiffness in Dry Rough Surface Contact Measured Using Longitudinal Ultrasonic Waves
Authors: Taghizadeh Saeid , Dwyer-Joyce Robert Sean
Published: June 2021

When two rough surfaces are loaded together contact occurs at asperity peaks. An interface of solid contact regions and air gaps is formed that is less stiff than the bulk material. The stiffness of a structure thus depends on the interface conditions; this is particularly critical when high stiffness is required, for example in precision systems such as machine tool spindles. The rough surface interface can be modelled as a distributed spring. For small deformation, the spring can be assumed to be linear; whilst for large deformations the spring gets stiffer as the amount of solid contact increases. One method to measure the spring stiffness, both the linear and nonlinear aspect, is by the reflection of ultrasound. An ultrasonic wave causes a perturbation of the contact and the reflection depends on the stiffness of the interface. In most conventional applications, the ultrasonic wave is low power, deformation is small and entirely elastic, and the linear stiffness is measured. However, if a high-powered ultrasonic wave is used, this changes the geometry of the contact and induces nonlinear response. In previous studies through transmission methods were used to measure the nonlinear interfacial stiffness. This approach is inconvenient for the study of machine elements where only one side of the interface is accessible. In this study a reflection method is undertaken, and the results are compared to existing experimental work with through transmission. The variation of both linear and nonlinear interfacial stiffnesses was measured as the nominal contact pressure was increased. In both cases interfacial stiffness was expressed as nonlinear differential equations and solved to deduce the contact pressure-relative surface approach relationships. The relationships derived from linear and nonlinear measurements were similar, indicating the validity of the presented methods.
A Biased Proportional-Integral-Derivative-Incorporated Latent Factor Analysis Model
Authors: Sui Jialu , Yin Jian
Published: June 2021

Nowadays, as the number of items is increasing and the number of items that users have access to is limited, user-item preference matrices in recommendation systems are always sparse. This leads to a data sparsity problem. The latent factor analysis (LFA) model has been proposed as the solution to the data sparsity problem. As the basis of the LFA model, the singular value decomposition (SVD) model, especially the biased SVD model, has great recommendation effects in high-dimensional sparse (HiDs) matrices. However, it has the disadvantage of requiring several iterations before convergence. Besides, the model PID-incorporated SGD-based LFA (PSL) introduces the principle of discrete PID controller into the stochastic gradient descent (SGD), the learning algorithm of the SVD model. It could solve the problem of slow convergence speed, but its accuracy of recommendation needs to be improved. In order to make better solution, this paper fuses the PSL model with the biased SVD model, hoping to obtain better recommendation result by combining their advantages and reconciling their disadvantages. The experiments show that this biased PSL model performs better than the traditional matrix factorization algorithms on different sizes of datasets.
Affinity-Based Task Scheduling on Heterogeneous Multicore Systems Using CBS and QBICTM
Authors: Abbasi Sohaib Iftikhar , Kamal Shaharyar , Gochoo Munkhjargal , Jalal Ahmad , Kim Kibum
Published: June 2021

This work presents the grouping of dependent tasks into a cluster using the Bayesian analysis model to solve the affinity scheduling problem in heterogeneous multicore systems. The non-affinity scheduling of tasks has a negative impact as the overall execution time for the tasks increases. Furthermore, non-affinity-based scheduling also limits the potential for data reuse in the caches so it becomes necessary to bring the same data into the caches multiple times. In heterogeneous multicore systems, it is essential to address the load balancing problem as all cores are operating at varying frequencies. We propose two techniques to solve the load balancing issue, one being designated “chunk-based scheduler” (CBS) which is applied to the heterogeneous systems while the other system is “quantum-based intra-core task migration” (QBICTM) where each task is given a fair and equal chance to run on the fastest core. Results show 30–55% improvement in the average execution time of the tasks by applying our CBS or QBICTM scheduler compare to other traditional schedulers when compared using the same operating system.
Vision-Based Path Guidance to Achieve Dies-Free Roller Hemming Process
Authors: Huang Yi-Ping , Jiang Bor-Tung , Wu Chia-Hung , Chang Jen-Yuan
Published: June 2021

Due to its high production flexibility, roller hemming has become the mainstream process for forming and joining metal sheets in the automotive industry. The traditional roller hemming process requires specific dies to support sheet metal parts and repeated offline manual adjustment of hemming routes, resulting in high die costs, high time consumption, and excessive labor inputs. The universal platform presented in this paper could replace specific dies to effectively reduce costs and expand production flexibility. To reach this objective, a vision-based automatic compensation path to achieve a dies-free roller hemming process is proposed and investigated in this paper. Hand–eye sensor modules assisted by multi-coordinate synchronization calibration for the roller hemming were designed to reconstruct three-dimensional (3-D) shape data of the incoming materials. Results from the proposed system were validated with experimental measurements for the sheet offset and the compensation of the arm hemming position, showing that the single-axis error can be reduced to ≤0.1 mm.
Hierarchical Electrode Switching Device Design for Distributed Single-Channel Electrical Resistivity Tomography System
Authors: Xia Xin , Pan Yu-Ying , Liu Xiao-Lei , Jia Yong-Gang
Published: June 2021

An electrode switching device (ESD) is one of the most important components of electrical resistivity tomography (ERT). It is a ligament and relay between a testing circuit and testing electrodes. Existing ESD uses a plane structure to realize the interconnection between ports and testing electrodes. Taking Wenner testing as an example, each electrode needs four additional switches. In this report, a new hardware saving ESD (HESD) is made with a hierarchical structure for a single-channel distributed ERT. HESD has two-layered switches to realize the conversion process. The first layer of 16 switches can realize four pairs of unrepeated connection between four ports—AMNB and four Lines—L1–L4. The second layer establishes the non-overlapping joints between four lines—L1–L4 and four testing electrodes. Each electrode only needs one switch for an 1D test, which has been wildly used in soil science, ocean probing, and contaminated surveys, and an odd number layer test. With the newly designed HESD, three fourths of the cost of hardware (switch) was saved compared with the conventional ESD. In addition, with two more switches, HESD was able to complete a 2D survey. The new two-layer HESD saves hardware costs and shows advantages in maintenance, system tests, and miniaturization, especially when many electrodes are required in an ERT system, which is very common in practice.
On Characteristics of Ice Ridges and Icebergs for Design of Ship Hulls in Polar Regions Based on Environmental Design Contours
Authors: Leira Bernt J. , Chai Wei , Radhakrishnan Gowtham
Published: June 2021

Ice ridges and icebergs generally pose a major threat to both ships and offshore facilities that operate in Polar regions. In many cases these features will govern the structural design loads associated with the Ultimate Limit State (ULS) and the Accidental Limit State (ALS). In general, a large number of load cases must be considered in order to ascertain an adequate structural resistance. Alternatively, conservatively high values of the relevant design parameters can be applied, which implies cost penalties. Accordingly, it is natural to consider methods that can serve to reduce the number of relevant load cases. Based on relevant information about the statistical properties of the parameters that characterize ice ridges and icebergs, the most likely combinations of these parameters for design purposes are highly relevant. On this background, the so-called environmental contour method is applied. Probabilistic models of the key parameters that govern the ship and ice interaction process are introduced. Subsequently, the procedure referred to as inverse reliability methods (IFORM) is applied for identification of the environmental contour. Different forms (i.e., dimensions) of environmental contours are generated to reflect the characteristics of the interaction process. Furthermore, the effect of an increasing correlation between the basic parameters is studied. In addition, the increase of the design parameter values for increasing encounter frequencies is illustrated.
Skeleton Tracking Accuracy and Precision Evaluation of Kinect V1, Kinect V2, and the Azure Kinect
Authors: Tölgyessy Michal , Dekan Martin , Chovanec Ľuboš
Published: June 2021

The Azure Kinect, the successor of Kinect v1 and Kinect v2, is a depth sensor. In this paper we evaluate the skeleton tracking abilities of the new sensor, namely accuracy and precision (repeatability). Firstly, we state the technical features of all three sensors, since we want to put the new Azure Kinect in the context of its previous versions. Then, we present the experimental results of general accuracy and precision obtained by measuring a plate mounted to a robotic manipulator end effector which was moved along the depth axis of each sensor and compare them. In the second experiment, we mounted a human-sized figurine to the end effector and placed it in the same positions as the test plate. Positions were located 400 mm from each other. In each position, we measured relative accuracy and precision (repeatability) of the detected figurine body joints. We compared the results and concluded that the Azure Kinect surpasses its discontinued predecessors, both in accuracy and precision. It is a suitable sensor for human–robot interaction, body-motion analysis, and other gesture-based applications. Our analysis serves as a pilot study for future HMI (human–machine interaction) designs and applications using the new Kinect Azure and puts it in the context of its successful predecessors.
Association of miRNA and mRNA Levels of the Clinical Onset of Multiple Sclerosis Patients
Authors: Piotrzkowska Danuta , Miller Elzbieta , Kucharska Ewa , Niwald Marta , Majsterek Ireneusz
Published: June 2021

Multiple sclerosis (MS) is a demyelinating disease characterized by chronic inflammation of the central nervous system, in which many factors can act together to influence disease susceptibility and progression. To date, the exact cause of MS is still unclear, but it is believed to result from an abnormal response of the immune system to one or more myelin antigens that develops in genetically susceptible individuals after their exposure to a, as yet undefined, causal agent. In our study, we assessed the effect of microRNAs on the expression level of neuroprotective proteins, including neurotrophins (BDNF and NT4/5), heat shock proteins (HSP70 and HSP27), and sirtuin (SIRT1) in peripheral blood mononuclear cells in the development of multiple sclerosis. The analysis of dysregulation of miRNA levels and the resulting changes in target mRNA/protein expression levels could contribute to a better understanding of the etiology of multiple sclerosis, as well as new alternative methods of diagnosis and treatment of this disease. The aim of this study was to find a link between neurotrophins (BDNF and NT4), SIRT1, heat shock proteins (HSP27 and HSP27), and miRNAs that are involved in the development of multiple sclerosis. The analysis of the selected miRNAs showed a negative correlation of SIRT1 with miR-132 and miR-34a and of BDNF with 132-3p in PBMCs, which suggests that the miRNAs we selected may regulate the expression level of the studied genes.
The Spatial Structure of Yazd Courtyard Houses: A Space Syntax Analysis of the Topological Characteristics of the Courtyard
Authors: Zolfagharkhani Mina , Ostwald Michael J.
Published: June 2021

An important “architectural type” in Iranian history is the Yazd courtyard house. This historic building type features a walled boundary that contains a complex pattern of open (to the sky), semi-enclosed and enclosed spaces. The planning of the courtyard in these houses has typically been interpreted as either a response to changing socio-cultural values or to local climatic conditions. Such theories about the planning of these houses are based on a series of assumptions about (i) the numbers of courtyards and rooms they contain, (ii) their unchanging nature over time and (iii) a topological pattern existing in the relationship between the courtyard and the rest of the plan. Yet, these assumptions, all of which have an impact on the socio-cultural or climatic interpretation of this famous architectural type, have never been tested. In response, this paper uses a computational and mathematical method drawn from Space Syntax to measure the spatial topology of 37 plans of Yazd’s most significant courtyard houses. These houses, which are classified by the Yazd Cultural Heritage Organization, were constructed between the 11th and 20th CE centuries and are all exemplars of this type. This paper develops three hypotheses around the assumptions found in past research about the characteristic planning of the Yazd courtyard house. Then, using quantitative measures derived from plan graph analysis, the paper develops a series of longitudinal trends to test the hypotheses and explore changes that have occurred in this architectural type over time.
Aqueous Extraction of Seed Oil from Mamey Sapote (Pouteria sapota) after Viscozyme L Treatment
Authors: Tacias-Pascacio Veymar G. , Rosales-Quintero Arnulfo , Rodrigues Rafael C. , Castañeda-Valbuena Daniel , Díaz-Suarez Pablo F. , Torrestiana-Sánchez Beatriz , Jiménez-Gómez Erik F. , Fernandez-Lafuente Roberto
Published: June 2021

In this study, aqueous enzymatic extraction (AEE) was evaluated during the process of obtaining oil from mamey sapote seed (OMSS). Viscozyme L enzyme complex was used at pH 4 and 50 °C during the optimization of the extraction process by central composite design and response surface methodology. Optimal conditions were: 3.5% (w/w) of enzyme (regarding the seed weight), 5.5 h of incubation time, 235 rpm of agitation rate, and 1:3.5 of solid-to-liquid ratio. These conditions enabled us to obtain an OMSS yield of 66%. No statistically significant differences were found in the fatty acid profile and physicochemical properties, such as the acid and iodine values and the percentage of free fatty acids, between the oil obtained by AEE or by the conventional solvent extraction (SE). However, the oxidative stability of the oil obtained by AEE (11 h) was higher than that obtained by SE (9.33 h), therefore, AEE, in addition to being an environmentally friendly method, produces a superior quality oil in terms of oxidative stability. Finally, the high oil content in mamey sapote seed, and the high percentage of oleic acid (around 50% of the total fatty acid) found in this oil, make it a useful edible vegetable oil.
New Stable Cell Lines Derived from the Proximal and Distal Intestine of Rainbow Trout (Oncorhynchus mykiss) Retain Several Properties Observed In Vivo
Authors: Pasquariello Rolando , Verdile Nicole , Pavlovic Radmila , Panseri Sara , Schirmer Kristin , Brevini Tiziana A. L. , Gandolfi Fulvio
Published: June 2021

We derived two novel cell lines from rainbow trout (RT) proximal (RTpi-MI) and distal intestine (RTdi-MI) and compared them with the previously established continuous cell line RTgutGC. Intestinal stem cells, differentiating and differentiated epithelial cells, and connective cells were found in all cell lines. The cell lines formed a polarized barrier, which was not permeable to large molecules and absorbed proline and glucose. High seeding density induced their differentiation into more mature phenotypes, as indicated by the downregulation of intestinal stem cell-related genes (i.e., sox9, hopx and lgr5), whereas alkaline phosphatase activity was upregulated. Other enterocyte markers (i.e., sglt1 and pept1), however, were not regulated as expected. In all cell lines, the presence of a mixed population of epithelial and stromal cells was characterized for the first time. The expression by the stromal component of lgr5, a stem cell niche regulatory molecule, may explain why these lines proliferate stably in vitro. Although most parameters were conserved among the three cell lines, some significant differences were observed, suggesting that characteristics typical of each tract are partly conserved in vitro as well.
Crystal Chemistry and Structural Complexity of the Uranyl Carbonate Minerals and Synthetic Compounds
Authors: Gurzhiy Vladislav V. , Kalashnikova Sophia A. , Kuporev Ivan V. , Plášil Jakub
Published: June 2021

Uranyl carbonates are one of the largest groups of secondary uranium(VI)-bearing natural phases being represented by 40 minerals approved by the International Mineralogical Association, overtaken only by uranyl phosphates and uranyl sulfates. Uranyl carbonate phases form during the direct alteration of primary U ores on contact with groundwaters enriched by CO2, thus playing an important role in the release of U to the environment. The presence of uranyl carbonate phases has also been detected on the surface of “lavas” that were formed during the Chernobyl accident. It is of interest that with all the importance and prevalence of these phases, about a quarter of approved minerals still have undetermined crystal structures, and the number of synthetic phases for which the structures were determined is significantly inferior to structurally characterized natural uranyl carbonates. In this work, we review the crystal chemistry of natural and synthetic uranyl carbonate phases. The majority of synthetic analogs of minerals were obtained from aqueous solutions at room temperature, which directly points to the absence of specific environmental conditions (increased P or T) for the formation of natural uranyl carbonates. Uranyl carbonates do not have excellent topological diversity and are mainly composed of finite clusters with rigid structures. Thus the structural architecture of uranyl carbonates is largely governed by the interstitial cations and the hydration state of the compounds. The information content is usually higher for minerals than for synthetic compounds of similar or close chemical composition, which likely points to the higher stability and preferred architectures of natural compounds.
Effect of High Pressure and Temperature on the Evolution of Si Phase and Eutectic Spacing in Al-20Si Alloys
Authors: Zhang Rong , Zou Chunming , Wei Zunjie , Wang Hongwei
Published: June 2021

The microstructure of the Si phase in Al-20Si alloys solidified under high pressure was investigated. The results demonstrate that the morphology of Si phase transformed (bulk→short rod→long needle) with the increase of superheat temperature under high pressure. At a pressure of 3 GPa and a superheat temperature of 100 K, a microstructure with a uniform distribution of fine Si phases on the α-Al matrix was obtained in the Al-20Si alloy. In addition, a mathematical model was developed to analyze the spacing variation of the lamellar Al-Si eutectics under the effect of pressure. The lamellar Al-Si eutectics appeared at 2 GPa and superheat temperatures of 70–150 K, and at 3 GPa and superheat temperatures of 140–200 K. With the increase of pressure from 2 GPa to 3 GPa, the average spacing of lamellar Al-Si eutectics decreased from 1.2–1.6 μm to 0.9–1.1 μm. In binary alloys, the effect of pressure on the eutectic spacing is related to the volume change of the solute phase from liquid to solid. When the volume change of the solute phase from liquid to solid is negative, the lamellar eutectic spacing decreases with increasing pressure. When it is positive, the eutectic spacing increases with increasing pressure.
Phenetic and Genetic Variability of Continental and Island Populations of the Freshwater Copepod Mastigodiaptomus ha Cervantes, 2020 (Copepoda): A Case of Dispersal?
Authors: Cervantes-Martínez Adrián , Gutiérrez-Aguirre Martha Angélica , Suárez-Morales Eduardo , Jaime Sarahi
Published: June 2021

The diversity of freshwater zooplankton is still little known in Mexico, particularly in reference to insular zooplankton communities. Diaptomid copepods (Crustacea: Copepoda: Calanoida) are a widespread group worldwide, and Mexico harbours high diaptomid diversity. Based on a recent sampling of freshwater zooplankton on a Caribbean Island of Mexico, we present the first record of a diaptomid copepod from an island freshwater ecosystem. It shows the well-known tendency of Neotropical diaptomids to have restricted distributional patterns and high levels of endemism. The species recorded, Mastigodiaptomus ha (Cervantes-Martínez, 2020) appears to have a restricted distribution in the Yucatan Peninsula (YP), and the island as well. In order to explore potential differences between the island and continental populations of this species, its phenetic and genetic diversity was analysed by performing morphological comparisons and also by exploring differences of the habitat conditions and genetic sequences (CO1 gene). Our analysis revealed a low (average = 0.33%) genetic divergence between both populations; likewise, both the morphology and habitat conditions closely resemble each other in these two populations. The low genetic divergence between the continental and island populations of M. ha suggests an early common origin of the species in the geological history of the YP.
Cerebral CT Perfusion in Acute Stroke: The Effect of Lowering the Tube Load and Sampling Rate on the Reproducibility of Parametric Maps
Authors: Ioannidis Georgios S. , Christensen Søren , Nikiforaki Katerina , Trivizakis Eleftherios , Perisinakis Kostas , Hatzidakis Adam , Karantanas Apostolos , Reyes Mauricio , Lansberg Maarten , Marias Kostas
Published: June 2021

The aim of this study was to define lower dose parameters (tube load and temporal sampling) for CT perfusion that still preserve the diagnostic efficiency of the derived parametric maps. Ninety stroke CT examinations from four clinical sites with 1 s temporal sampling and a range of tube loads (mAs) (100–180) were studied. Realistic CT noise was retrospectively added to simulate a CT perfusion protocol, with a maximum reduction of 40% tube load (mAs) combined with increased sampling intervals (up to 3 s). Perfusion maps from the original and simulated protocols were compared by: (a) similarity using a voxel-wise Pearson’s correlation coefficient r with in-house software; (b) volumetric analysis of the infarcted and hypoperfused volumes using commercial software. Pearson’s r values varied for the different perfusion metrics from 0.1 to 0.85. The mean slope of increase and cerebral blood volume present the highest r values, remaining consistently above 0.7 for all protocol versions with 2 s sampling interval. Reduction of the sampling rate from 2 s to 1 s had only modest impacts on a TMAX volume of 0.4 mL (IQR −1–3) (p = 0.04) and core volume of −1.1 mL (IQR −4–0) (p < 0.001), indicating dose savings of 50%, with no practical loss of diagnostic accuracy. The lowest possible dose protocol was 2 s temporal sampling and a tube load of 100 mAs.
Correlation of Native Liver Parenchyma T1 and T2 Relaxation Times and Liver Synthetic Function Tests: A Pilot Study
Authors: Fahlenkamp Ute Lina , Kunkel Jan , Ziegeler Katharina , Neumann Konrad , Adams Lisa Christine , Engel Günther , Böker Sarah Maria , Makowski Marcus Richard
Published: June 2021

MR relaxometry increasingly contributes to liver imaging. Studies on native relaxation times mainly describe relation to the presence of fibrosis. The hypothesis was that relaxation times are also influenced by other inherent factors, including changes in liver synthesis function. With the approval of the local ethics committee and written informed consent, data from 94 patients referred for liver MR imaging, of which 20 patients had cirrhosis, were included. Additionally to standard sequences, both native T1 and T2 parametric maps and T1 maps in the hepatobiliary phase of gadoxetate disodium were acquired. Associations with laboratory variables were assessed. Altogether, there was a negative correlation between albumin and all acquired relaxation times in cirrhotic patients. In non-cirrhotic patients, only T1 values exhibited a negative correlation with albumin. In all patients, bilirubin correlated significantly with post-contrast T1 relaxation times, whereas native relaxation times correlated only in cirrhotic patients. Evaluating patients with pathological INR values, post-contrast relaxation times were significantly higher, whereas native relaxation times did not correlate. In conclusion, apart from confirming the value of hepatobiliary phase T1 mapping, our results show a correlation of native T1 with serum albumin even in non-cirrhotic liver parenchyma, suggesting a direct influence of liver’s synthesis capacity on T1 relaxation times.
Variable-Order Fractional Models for Wall-Bounded Turbulent Flows
Authors: Song Fangying , Karniadakis George Em
Published: June 2021

Modeling of wall-bounded turbulent flows is still an open problem in classical physics, with relatively slow progress in the last few decades beyond the log law, which only describes the intermediate region in wall-bounded turbulence, i.e., 30–50 y+ to 0.1–0.2 R+ in a pipe of radius R. Here, we propose a fundamentally new approach based on fractional calculus to model the entire mean velocity profile from the wall to the centerline of the pipe. Specifically, we represent the Reynolds stresses with a non-local fractional derivative of variable-order that decays with the distance from the wall. Surprisingly, we find that this variable fractional order has a universal form for all Reynolds numbers and for three different flow types, i.e., channel flow, Couette flow, and pipe flow. We first use existing databases from direct numerical simulations (DNSs) to lean the variable-order function and subsequently we test it against other DNS data and experimental measurements, including the Princeton superpipe experiments. Taken together, our findings reveal the continuous change in rate of turbulent diffusion from the wall as well as the strong nonlocality of turbulent interactions that intensify away from the wall. Moreover, we propose alternative formulations, including a divergence variable fractional (two-sided) model for turbulent flows. The total shear stress is represented by a two-sided symmetric variable fractional derivative. The numerical results show that this formulation can lead to smooth fractional-order profiles in the whole domain. This new model improves the one-sided model, which is considered in the half domain (wall to centerline) only. We use a finite difference method for solving the inverse problem, but we also introduce the fractional physics-informed neural network (fPINN) for solving the inverse and forward problems much more efficiently. In addition to the aforementioned fully-developed flows, we model turbulent boundary layers and discuss how the streamwise variation affects the universal curve.
Hybrid Multicarrier Random Space Vector PWM for the Mitigation of Acoustic Noise
Authors: Madasamy P. , Verma Rajesh , Bharatiraja C. , J. Barnabas Paul Glady , Srihari T. , Munda Josiah Lange , Mihet-Popa Lucian
Published: June 2021

The pulse width modulation (PWM) inverter is an obvious choice for any industrial and power sector application. Particularly, industrial drives benefit from the higher DC-link utilization, acoustic noise, and vibration industrial standards. Many PWM techniques have been proposed to meet the drives’ demand for higher DC-link utilization and lower harmonics suppression and noise reductions. Still, random PWM (RPWM) is the best candidate for reducing the acoustic noises. Few RPWM (RPWM) methods have been developed and investigated for the AC drive’s PWM inverter. However, due to the lower randomness of the multiple frequency harmonics spectrum, reducing the drive noise is still challenging. These PWMs dealt with the spreading harmonics, thereby decreasing the harmonic effects on the system. However, these techniques are unsuccessful at maintaining the higher DC-link utilizations. Existing RPWM methods have less randomness and need complex digital circuitry. Therefore, this paper mainly deals with a combined RPWM principle in space vector PWM (SVPWM) to generate random PWM generation using an asymmetric frequency multicarrier called multicarrier random space vector PWM (MCRSVPWM). he SVPWM switching vectors with different frequency carrier are chosen with the aid of a random bi-nary bit generator. The proposed MCRSVPWM generates the pulses with a randomized triangular carrier (1 to 4 kHz), while the conventional RPWM method contains a random pulse position with a fixed frequency triangular carrier. The proposed PWM is capable of eradicating the high-frequency unpleasant acoustic noise more effectually than conventional RPWM with a shorter random frequency range. The simulation study is performed through MATLAB/Simulink for a 2 kW asynchronous induction motor drive. Experimental validation of the proposed MCRSVPWM is tested with a 2 kW six-switch (Power MOSFET–SCH2080KE) inverter power module-fed induction motor drive.
Collision Avoidance Geographic P2P-RPL in Multi-Hop Indoor Wireless Networks
Authors: Choi Yunyoung , Park Jaehyung , Jung Jiwon , Kwon Younggoo
Published: June 2021

In home and building automation applications, wireless sensor devices need to be connected via unreliable wireless links within a few hundred milliseconds. Routing protocols in Low-power and Lossy Networks (LLNs) need to support reliable data transmission with an energy-efficient manner and short routing convergence time. IETF standardized the Point-to-Point RPL (P2P-RPL) routing protocol, in which P2P-RPL propagates the route discovery messages over the whole network. This leads to significant routing control packet overhead and a large amount of energy consumption. P2P-RPL uses the trickle algorithm to control the transmission rate of routing control packets. The non-deterministic message suppression nature of the trickle algorithm may generate a sub-optimal routing path. The listen-only period of the trickle algorithm may lead to a long network convergence time. In this paper, we propose Collision Avoidance Geographic P2P-RPL, which achieves energy-efficient P2P data delivery with a fast routing request procedure. The proposed algorithm uses the location information to limit the network search space for the desired route discovery to a smaller location-constrained forwarding zone. The Collision Avoidance Geographic P2P-RPL also dynamically selects the listen-only period of the trickle timer algorithm based on the transmission priority related to geographic position information. The location information of each node is obtained from the Impulse-Response Ultra-WideBand (IR-UWB)-based cooperative multi-hop self localization algorithm. We implement Collision Avoidance Geographic P2P-RPL on Contiki OS, an open-source operating system for LLNs and the Internet of Things. The performance results show that the Collision Avoidance Geographic P2P-RPL reduced the routing control packet overheads, energy consumption, and network convergence time significantly. The cooperative multi-hop self localization algorithm improved the practical implementation characteristics of the P2P-RPL protocol in real world environments. The collision avoidance algorithm using the dynamic trickle timer increased the operation efficiency of the P2P-RPL under various wireless channel conditions with a location-constrained routing space.
Topological Review of Quasi-Switched Boost Inverters
Authors: Barath JG Nataraj , Soundarrajan Ayyasamy , Stepenko Serhii , Husev Oleksandr , Vinnikov Dmitri , Nguyen Minh-Khai
Published: June 2021

This paper presents a comprehensive review based on the features and drawbacks of the quasi-switched boost inverter (qSBI) topologies. The qSBI derived configurations are well suitable for low power applications due to their reduced number of components. This work focuses on the topological review of qSBI derived topologies and serves as a reference for further derivation and research on the selection of suitable topology for the specific renewable energy applications, particularly based on the photovoltaic (PV) converters.
Triple-Band Uniform Circular Array Antenna for a Multi-Functional Radar System
Authors: Kim Ilkyu , Lee Sun-Gyu , Lee Jeong-Hae
Published: June 2021

A phased array radar has been developed toward an effective means for integrating multiple functionalities into one radar platform. The radar system necessitates the ability to operate at multiple frequencies simultaneously. In this paper, a triple-band uniform radial sub-array using a shared aperture antenna is proposed for a multi-functional radar system. An efficient placement of different radiating elements is realized based on the radial displacement of the circular array. In addition, multi-layer feed networks are used to reduce the intricacy of integrating several feed networks into one antenna. The reasonable matching characteristics and far-field gain are acquired at the S-band, C-band, and X-band. The measured results of the prototype are presented, and the results are compared to the simulation, which showed a good agreement.
AREEBA: An Area Efficient Binary Huff-Curve Architecture
Authors: Sajid Asher , Rashid Muhammad , Jamal Sajjad Shaukat , Imran Malik , Alotaibi Saud S. , Sinky Mohammed H.
Published: June 2021

Elliptic curve cryptography is the most widely employed class of asymmetric cryptography algorithm. However, it is exposed to simple power analysis attacks due to the lack of unifiedness over point doubling and addition operations. The unified crypto systems such as Binary Edward, Hessian and Huff curves provide resistance against power analysis attacks. Furthermore, Huff curves are more secure than Edward and Hessian curves but require more computational resources. Therefore, this article has provided a low area hardware architecture for point multiplication computation of Binary Huff curves over GF(2163) and GF(2233). To achieve this, a segmented least significant digit multiplier for polynomial multiplications is proposed. In order to provide a realistic and reasonable comparison with state of the art solutions, the proposed architecture is modeled in Verilog and synthesized for different field programmable gate arrays. For Virtex-4, Virtex-5, Virtex-6, and Virtex-7 devices, the utilized hardware resources in terms of hardware slices over GF(2163) are 5302, 2412, 2982 and 3508, respectively. The corresponding achieved values over GF(2233) are 11,557, 10,065, 4370 and 4261, respectively. The reported low area values provide the acceptability of this work in area-constrained applications.
Temperature Dependent Analytical Model for the Threshold Voltage of the SiC VJFET with a Lateral Asymmetric Channel
Authors: Ghedira Sami , Fargi Abdelaali , Besbes Kamel
Published: June 2021

The wide-bandgap (WBG) semiconductor devices for modern power electronics require intensive efforts for the analysis of the critical aspects of their operation. In recent years, silicon carbide (SiC) based field effect transistor have been extensively investigated. Motivated by the significant employment of the SiC Vertical Junction Field Effect transistors with lateral channel (LC-VJFET) in the development of high-voltage and high temperature applications, the properties of the LC-VJFET device are investigated in this work. The most important normally-ON LC-VJFET parameter is their threshold voltage (VTh), which is defined as the gate-to-source voltage necessary to block the device. The higher complexity of the blocking operation of the normally-ON device makes the accurate knowledge of the VTh as a fundamental issue. In this paper, a temperature dependent analytical model for the threshold voltage of the normally-ON LC-VJFET is developed. This analytical model is derived based on a numerical analysis of the electrical potential distribution along the asymmetrical lateral channel in the blocking operation. To validate our model, the analytical results are compared to 2D numerical simulations and experimental results for a wide temperature range.
RYEL: An Experimental Study in the Behavioral Response of Judges Using a Novel Technique for Acquiring Higher-Order Thinking Based on Explainable Artificial Intelligence and Case-Based Reasoning
Authors: Rodríguez Oconitrillo Luis Raúl , Vargas Juan José , Camacho Arturo , Burgos Álvaro , Corchado Juan Manuel
Published: June 2021

The need for studies connecting machine explainability with human behavior is essential, especially for a detailed understanding of a human’s perspective, thoughts, and sensations according to a context. A novel system called RYEL was developed based on Subject-Matter Experts (SME) to investigate new techniques for acquiring higher-order thinking, the perception, the use of new computational explanatory techniques, support decision-making, and the judge’s cognition and behavior. Thus, a new spectrum is covered and promises to be a new area of study called Interpretation-Assessment/Assessment-Interpretation (IA-AI), consisting of explaining machine inferences and the interpretation and assessment from a human. It allows expressing a semantic, ontological, and hermeneutical meaning related to the psyche of a human (judge). The system has an interpretative and explanatory nature, and in the future, could be used in other domains of discourse. More than 33 experts in Law and Artificial Intelligence validated the functional design. More than 26 judges, most of them specializing in psychology and criminology from Colombia, Ecuador, Panama, Spain, Argentina, and Costa Rica, participated in the experiments. The results of the experimentation have been very positive. As a challenge, this research represents a paradigm shift in legal data processing.
A New RBF Neural Network-Based Fault-Tolerant Active Control for Fractional Time-Delayed Systems
Authors: Wang Bo , Jahanshahi Hadi , Volos Christos , Bekiros Stelios , Khan Muhammad Altaf , Agarwal Praveen , Aly Ayman A.
Published: June 2021

Recently, intelligent control techniques have received considerable attention. In most studies, the systems’ model is assumed to be without any delay, and the effects of faults and failure in actuators are ignored. However, in real practice, sensor malfunctioning, mounting limitation, and defects in actuators bring about faults, failure, delay, and disturbances. Consequently, applying controllers that do not consider these problems could significantly deteriorate controllers’ performance. In order to address this issue, in the current paper, we propose a new neural network-based fault-tolerant active control for fractional time-delayed systems. The neural network estimator is integrated with active control to compensate for all uncertainties and disturbances. The suggested method’s stability is achieved based on the concept of active control and the Lyapunov stability theorem. Then, a fractional-order memristor system is investigated, and some characteristics of this chaotic system are studied. Lastly, by applying the proposed control scheme, synchronization results of the fractional time-delayed memristor system in the presence of faults and uncertainties are studied. The simulation results suggest the effectiveness of the proposed control technique for uncertain time-delayed nonlinear systems.
Tree Height Growth Modelling Using LiDAR-Derived Topography Information
Authors: Kobal Milan , Hladnik David
Published: June 2021

The concepts of ecotopes and forest sites are used to describe the correlative complexes defined by landform, vegetation structure, forest stand characteristics and the relationship between soil and physiography. Physically heterogeneous landscapes such as karst, which is characterized by abundant sinkholes and outcrops, exhibit diverse microtopography. Understanding the variation in the growth of trees in a heterogeneous topography is important for sustainable forest management. An R script for detailed stem analysis was used to reconstruct the height growth histories of individual trees (steam analysis). The results of this study reveal that the topographic factors influencing the height growth of silver fir trees can be detected within forest stands. Using topography modelling, we classified silver fir trees into groups with significant differences in height growth. This study provides a sound basis for the comparison of forest site differences and may be useful in the calibration of models for various tree species.
Exploration of Semantic Geo-Object Recognition Based on the Scale Parameter Optimization Method for Remote Sensing Images
Authors: Wang Jun , Jiang Lili , Qi Qingwen , Wang Yongji
Published: June 2021

Image segmentation is of significance because it can provide objects that are the minimum analysis units for geographic object-based image analysis (GEOBIA). Most segmentation methods usually set parameters to identify geo-objects, and different parameter settings lead to different segmentation results; thus, parameter optimization is critical to obtain satisfactory segmentation results. Currently, many parameter optimization methods have been developed and successfully applied to the identification of single geo-objects. However, few studies have focused on the recognition of the union of different types of geo-objects (semantic geo-objects), such as a park. The recognition of semantic geo-objects is likely more crucial than that of single geo-objects because the former type of recognition is more correlated with the human perception. This paper proposes an approach to recognize semantic geo-objects. The key concept is that a single geo-object is the smallest component unit of a semantic geo-object, and semantic geo-objects are recognized by iteratively merging single geo-objects. Thus, the optimal scale of the semantic geo-objects is determined by iteratively recognizing the optimal scales of single geo-objects and using them as the initiation point of the reset scale parameter optimization interval. In this paper, we adopt the multiresolution segmentation (MRS) method to segment Gaofen-1 images and tested three scale parameter optimization methods to validate the proposed approach. The results show that the proposed approach can determine the scale parameters, which can produce semantic geo-objects.
B-Type Natriuretic Peptides and High-Sensitive Troponin I as COVID-19 Survival Factors: Which One Is the Best Performer?
Authors: de Falco Renato , Vargas Maria , Palma Daniela , Savoia Marcella , Miscioscia Anna , Pinchera Biagio , Vano Martina , Servillo Giuseppe , Gentile Ivan , Fortunato Giuliana
Published: June 2021

Increased concentrations of B-type natriuretic peptide (BNP), N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity troponin I (HsTnI) in COVID-19 patients have already been reported. The aim of this study is to evaluate which of these common markers of cardiac disease is the most useful predictor of fatal outcome in COVID-19 patients. One hundred and seventy-four patients affected with COVID-19 were recruited, and markers of cardiac disease and the clinical history of the patients were collected at admission in the infectious disease unit or intensive care unit. NT-proBNP, BNP and HsTnI values were higher in in-hospital non-surviving patients. Receiver operating characteristic (ROC) curve analysis of NT-proBNP, BNP and HsTnI was performed, with NT-proBNP (AUC = 0.951) and HsTnI (AUC = 0.947) being better performers (p = 0.01) than BNP (AUC = 0.777). Logistic regression was performed assessing the relation of HsTnI and NT-proBNP to fatal outcome adjusting for age and gender, with only NT-proBNP being significant. The population was then divided into two groups, one with higher NT-proBNP values at admission than the cut-off resulted from the ROC curve (511 ng/L) and a second one with lower values. The Kaplan–Meier analysis showed an absence of fatal outcome in the group of patients with NT-proBNP values lower than the cut-off (p < 0.001). NT-proBNP proved to be the best prognostic tool for fatal outcome among markers of cardiac disease in COVID-19 patients.
Uric Acid as a Predictor for Early Allograft Dysfunction after Living Donor Liver Transplantation: A Prospective Observational Study
Authors: Hu Li-Min , Tsai Hsin-I , Lee Chao-Wei , Chen Hui-Ming , Lee Wei-Chen , Yu Huang-Ping
Published: June 2021

Early allograft dysfunction (EAD) is a postoperative complication that may cause graft failure and mortality after liver transplantation. The objective of this study was to examine whether the preoperative serum uric acid (SUA) level may predict EAD. We performed a prospective observational study, including 61 donor/recipient pairs who underwent living donor liver transplantation (LDLT). In the univariate and multivariate analysis, SUA ≤4.4 mg/dL was related to a five-fold (odds ratio (OR): 5.16, 95% confidence interval (CI): 1.41–18.83; OR: 5.39, 95% CI: 1.29–22.49, respectively) increased risk for EAD. A lower preoperative SUA was related to a higher incidence of and risk for EAD. Our study provides a new predictor for evaluating EAD and may exert a protective effect against EAD development.
Adherence to European Guidelines for Treatment and Management of Pancreatic Exocrine Insufficiency in Chronic Pancreatitis Patients
Authors: Khan Mashroor , Rutkowski Wiktor , Vujasinovic Miroslav , Löhr Johannes Matthias
Published: June 2021

European evidence-based guidelines for the treatment and management of chronic pancreatitis (CP) have been made available following the harmonizing diagnosis and treatment of CP across Europe (HaPanEU) initiative by the United European Gastroenterology (UEG). The aim of this study was to evaluate adherence to the guideline recommendations in the management of patients with pancreatic exocrine insufficiency (PEI) at Karolinska University Hospital in Stockholm. UEG guideline recommendations were evaluated and categorized into 55 different quality indicators (QIs). Data from a retrospective cohort of CP patients being treated at Karolinska University Hospital were evaluated with regard to overall adherence as well as adherence to specific QIs. A total number of 118 patients out of 956 patients diagnosed with CP were eligible for inclusion with mean overall adherence of 61.9% to the defined QIs. A significant difference in mean overall adherence was shown between patients diagnosed with CP prior to 1 January 2016 and following 1 January 2016 (59.3% and 67.7% respectively, p = 0.004), with linear regression analysis also demonstrating improvement correlating to date of diagnosis (p = 0.002). In conclusion, diagnosis and treatment of PEI improved after the HaPanEU guidelines became available and is continuously improving; however, there is room for further improvement.