bluuebunny/crossref_metadata_2025 huggingface dataset:
Physical, Psychological and Social Frailty Are Predictive of Heart Failure: A Cross-Sectional Study
Authors: Uchmanowicz Izabella , Pasieczna Aleksandra H. , Wójta-Kempa Monika , Gobbens Robbert J. J. , Młynarska Agnieszka , Faulkner Kenneth M. , Czapla Michał , Szczepanowski Remigiusz
Published: January 2022

Background: Little is known about frailty among patients hospitalized with heart failure (HF). To date, the limited information on frailty in HF is based on a unidimensional view of frailty, in which only physical aspects are considered when determining frailty. The aims of this study were to study different dimensions of frailty (physical, psychological and social) in patients with HF and the effect of different dimensions of frailty on the incidence of heart failure. Methods: The study used a cross-sectional design and included 965 patients hospitalized for heart failure and 164 healthy controls. HF was defined according to the ESC guidelines. The Tilburg Frailty Indicator (TFI) was used to assess frailty. Probit regression analyses and chi-square statistics were used to examine associations between the occurrence of heart failure and TFI domains of frailty. Results: Patients diagnosed with frailty were 15.3% more likely to develop HF compared to those not diagnosed with frailty (p < 0.001). An increase in physical, psychological and social frailty corresponded to an increased risk of HF of 2.9% (p < 0.001), 4.4% (p < 0.001) and 6.6% (p < 0.001), respectively. Conclusions: We found evidence of the association between different dimensions of frailty and incidence of HF.
Reflex Locomotion Therapy for Balance, Gait, and Fatigue Rehabilitation in Subjects with Multiple Sclerosis
Authors: Carratalá-Tejada María , Cuesta-Gómez Alicia , Ortiz-Gutiérrez Rosa , Molina-Rueda Francisco , Luna-Oliva Laura , Miangolarra-Page Juan Carlos
Published: January 2022

This study evaluates the effects of a rehabilitation program based on reflex locomotion therapy (RLT) on balance, gait, and fatigue in patients with multiple sclerosis (MS). Twenty-three patients diagnosed with MS participated in this study. Reversal design was carried out. The assessment tools included the Berg Balance Scale (BBS), the Performance Oriented Mobility Assessment (POMA), the Fatigue Severity Scale (FSS) and the instrumental analysis of the gait recorded by Vicon Motion System®. We analyzed spatio-temporal parameters and kinematic variables of the hip, knee, and ankle joints. Additionally, the Client Satisfaction Questionnaire (CSQ-8) was administrated. We did find a significant improvement in balance and gait tools after the RLT period. Regarding instrumental analysis, the statistical analysis of spatio-temporal parameters showed a significant improvement in stride length, double support, and velocity after the RLT period. Concerning kinematic parameters, the analysis showed improvements in hip and knee range of motion (ROM) after RLT period. RLT could improve gait and balance in patients with MS. The patients reported a high level of satisfaction with the therapy received.
The Deficit Schizophrenia Subtype Is Associated with Low Adherence to the Mediterranean Diet: Findings from a Case–Control Study
Authors: Kowalski Krzysztof , Bogudzińska Bogna , Stańczykiewicz Bartłomiej , Piotrowski Patryk , Bielawski Tomasz , Samochowiec Jerzy , Szczygieł Krzysztof , Plichta Piotr , Misiak Błażej
Published: January 2022

Accumulating evidence indicates that individuals with schizophrenia show poor dietary habits that might account for increased susceptibility to cardiovascular diseases in this population. However, it remains unknown whether this observation can be generalized over the whole population of individuals with schizophrenia. Therefore, in this study we aimed to investigate dietary habits, in terms of adherence to the Mediterranean diet (MD) in subjects with the deficit subtype of schizophrenia (SCZ-D), those with non-deficit subtype (SCZ-ND), and healthy controls (HCs). We recruited 45 individuals with SCZ-ND, 40 individuals with SCZ-D, and 60 HCs. Dietary habits were assessed using the Food Frequency Questionnaire-6 with a 12-month recall. Adherence to MD was decreased only in subjects with SCZ-D compared with HCs. Lower adherence to MD was associated with significantly higher levels of clinician-rated and self-reported negative symptoms (including alogia, avolition, and anhedonia). No significant correlations of adherence to MD with depressive symptoms were found. Lower adherence to MD was related to significantly higher body mass index in subjects with schizophrenia, but not in HCs. Our results indicate that poor adherence to MD is associated with a diagnosis of SCZ-D, higher severity of negative symptoms, and greater risk of developing overweight or obesity.
Vat Photopolymerization Additive Manufacturing of Functionally Graded Materials: A Review
Authors: Nohut Serkan , Schwentenwein Martin
Published: January 2022

Functionally Graded Materials (FGMs) offer discrete or continuously changing properties/compositions over the volume of the parts. The widespread application of FGMs was not rapid enough in the past due to limitations of the manufacturing methods. Significant developments in manufacturing technologies especially in Additive Manufacturing (AM) enable us nowadays to manufacture materials with specified changes over the volume/surface of components. The use of AM methods for the manufacturing of FGMs may allow us to compensate for some drawbacks of conventional methods and to produce complex and near-net-shaped structures with better control of gradients in a cost-efficient way. Vat Photopolymerization (VP), a type of AM method that works according to the principle of curing liquid photopolymer resin layer-by-layer, has gained in recent years high importance due to its advantages such as low cost, high surface quality control, no need to support structures, no limitation in the material. This article reviews the state-of-art and future potential of using VP methods for FGM manufacturing. It was concluded that improvements in printer hardware setup and software, design aspects and printing methodologies will accelerate the use of VP methods for FGMs manufacturing.
Detrital Zircon Provenance in the Sediments in the Southern Okinawa Trough
Authors: Zhu Bowen , Zeng Zhigang
Published: January 2022

The provenance of sediments in the Southern Okinawa Trough since the late Holocene has been a controversial scientific issue during the past 20 years. Previous studies based on isotope proxies generally indicated Taiwanese rivers as the primary source in the Southern Okinawa Trough since the late Holocene. Based on the zircon U-Pb geochronology, this study identified how sediments from the Yangtze River/East China Sea shelf had contributed significantly to the Southern Okinawa Trough in the past 624 a BP. Notably, this study found two Paleoarchean zircon grains, which indicated they originated from older orogenic belts. These data shed new light on the provenance of sediments, and a partial supply from the mainland of China cannot be excluded.
A Method for Measuring Hydrodynamic Force Coefficients Applied to an Articulated Concrete Mattress
Authors: An Hongwei , Hu Xiaoyuan , Draper Scott , Cheng Liang , Lubis Binsar , Kimiaei Mehrdad
Published: January 2022

A physical model testing method to determine the hydrodynamic force coefficients of an object is proposed and applied to an articulated concrete mattress placed on a flat surface under steady current condition. The test setup, which comprises of a pulley system that is able to pull the concrete mattress in either direction relative to the flow (e.g., with the flow direction or against the flow direction) and one load cell to measure the force required to pull the mattress, is simple and straightforward. Writing the equations of load balance for two different pulling directions allows the force coefficients to be deduced. The novelty and advantages of the method are that it completely removes the difficulties associated with measuring forces on individual concrete blocks and isolating the mattresses from contacting the solid surface, which were common in conventional test methods for measuring hydrodynamic forces on structures founded on a solid surface. A series of flume tests have been conducted to demonstrate the validity of the proposed method. It is expected that the proposed testing method is applicable to a wide range of structures, bed surfaces and flow conditions.
Morphological Development and Behaviour of a Shoreface Nourishment in the Portuguese Western Coast
Authors: Pinto Celso Aleixo , Taborda Rui , Andrade César , Baptista Paulo , Silva Paulo Alves , Mendes Diogo , Pais-Barbosa Joaquim
Published: January 2022

Current coastal protection strategy in Portugal defines beach and shoreface nourishment as a valid measure to mitigate coastal erosion in some erosional hot-spots, being considered as an adaptation measure under the present climate change scenario, including the impacts of sea level rise. However, scant objective data on shoreface nourishments are available to evaluate performance of this type of intervention in mitigating beach erosion and managing coast risk. We present the first monitoring results of a ≈2.4 × 106 m3 shoreface nourishment on the Aveiro coast (Costa Nova—Ílhavo), the largest until now in Portugal, focusing on its morphological development, impacts on adjacent beaches due to alongshore spreading and cross-shore redistribution, and contribution to the sediment budget of the nourished sediment cell. The analyses are based on high-resolution coastal monitoring data, provided by the Portuguese COaStal MOnitoring Program (COSMO). A Multiple Monitoring Cell (MMC) approach was used to evaluate local and feeder efficiency of the nourishment, sediment budget exchanges within both the placement and wider survey domains (≈1 km2 and 12 km2, respectively). Results show rapid (ca. 6 months) morphological change over the placement area, with a decrease of about 40% of the initial volume. Fast onshore sediment redistribution explains part of this change, placed sand having merged with the pre-existing bar system increased the volume of the shallower nearshore. Longshore transport is reflected by increasing the robustness of the bar downdrift of the placement area and also explains the negative sediment budget (0.75 × 106 m3) of the survey domain, which corresponds to losses through its southern boundary. Sediment spreading also induced accretion of the subaerial section of Costa Nova beaches in front of the placement area, reversing their long-term erosive trend. In contrast, this trend persisted at downdrift beaches. This suggests that the time lag of the subaerial beach response to this intervention increases with the distance to the placement area, and reversal of the erosive trend will only be noticeable in the following years. This study provides new insights on the time scales of beach response to high-magnitude shoreface interventions in high-energy wave-dominated sandy coasts, which will support decision making regarding similar operations designed to manage erosional hot-spots elsewhere.
Floating Behavior of a Composite Bucket Foundation under the Combined Action of Wind and Waves
Authors: Zhao Xing , Zhang Puyang , Le Conghuan , Ding Hongyan
Published: January 2022

In this study, a composite bucket foundation (CBF) was investigated by taking into account the reflection and refraction effects of waves. A numerical model for the motion responses of the structure under different wave heights and wave periods was built based on the 3D potential flow theory. The model was verified against the test results for analyzing the stability and seakeeping performance of the foundation under the action of waves. Under the combined action of wind and waves, the possible scenarios of floating under wind and waves of different scales and directions were simulated, and the mooring force and motion response peaks and laws of the structure were established, aiming to improve the safety of composite bucket foundation transport and provide technical support for floating construction.
Enhancing the Biocontrol Potential of the Entomopathogenic Fungus in Multiple Respects via the Overexpression of a Transcription Factor Gene MaSom1
Authors: Du Yanru , Xia Yuxian , Jin Kai
Published: January 2022

Entomopathogenic fungi play important roles in the control of populations of agricultural and disease vector pests in nature. The shortcomings of mycoinsecticides for pest management in the field cannot be completely overcome by improving single biocontrol properties of fungi. Therefore, enhancing the biocontrol potential of entomopathogenic fungi in multiple respects by genetic engineering is desirable. Transcription factors are usually involved in various important processes during fungal growth and pathogenesis via regulating a series of genes, and are important candidates for fungal improvement via genetic engineering. Herein, overexpression of MaSom1, a key transcription factor gene in the cAMP/PKA pathway, improves the biocontrol traits of Metarhizium acridum in multiple respects. When compared with WT, the MaSom1-overexpression strains exhibit enhanced tolerances to UV-B and heat shock, with increased mean 50% inhibition times by 66.9% and 155.2%, respectively. Advanced conidiation emerged accompanied by increased conidial yield up to 3.89 times after 3-day incubation for the MaSom1-overexpression strains compared to WT. Furthermore, when compared with WT, the virulence of the MaSom1-overexpression strains was also increased with the mean 50% lethality times reduced by 21.8% to 23.8%. Taken together, the MaSom1-overexpression improved the biocontrol potential of M. acridum in multiple respects. Our results provide insights into the application of key transcription factors for genetic engineering and offer a credible way to further improve the biocontrol potential of entomopathogenic fungi.
COVID-19: Barriers to Physical Activity in Older Adults, a Decline in Health or Economy?
Authors: Jiao Jiao , Supriya Rashmi , Chow Bik C. , Baker Julien S. , Dutheil Frédéric , Gao Yang , Chan Sze-Hoi , Liang Wei , Li Feifei , Tao Dan
Published: January 2022

Since spring 2020, in response to the global threat of the Coronavirus Disease 2019 (COVID-19) pandemic, several governments implemented emergency policies and regulations to prevent further transmission of the disease (Portegijs et al [...]
SDMob: SDN-Based Mobility Management for IoT Networks
Authors: Rabet Iliar , Selvaraju Shunmuga Priyan , Fotouhi Hossein , Alves Mário , Vahabi Maryam , Balador Ali , Björkman Mats
Published: January 2022

Internet-of-Things (IoT) applications are envisaged to evolve to support mobility of devices while providing quality of service in the system. To keep the connectivity of the constrained nodes upon topological changes, it is of vital importance to enhance the standard protocol stack, including the Routing Protocol for Lossy Low-power Networks (RPL), with accurate and real-time control decisions. We argue that devising a centralized mobility management solution based on a lightweight Software Defined Networking (SDN) controller provides seamless handoff with reasonable communication overhead. A centralized controller can exploit its global view of the network, computation capacity, and flexibility, to predict and significantly improve the responsiveness of the network. This approach requires the controller to be fed with the required input and to get involved in the distributed operation of the standard RPL. We present SDMob, which is a lightweight SDN-based mobility management architecture that integrates an external controller within a constrained IoT network. SDMob lifts the burden of computation-intensive filtering algorithms away from the resource-constrained nodes to achieve seamless handoffs upon nodes’ mobility. The current work extends our previous work, by supporting multiple mobile nodes, networks with a high density of anchors, and varying hop-distance from the controller, as well as harsh and realistic mobility patterns. Through analytical modeling and simulations, we show that SDMob outperforms the baseline RPL and the state-of-the-art ARMOR in terms of packet delivery ratio and end-to-end delay, with an adjustable and tolerable overhead. With SDMob, the network provides close to 100% packet delivery ratio (PDR) for a limited number of mobile nodes, and maintains sub-meter accuracy in localization under random mobility patterns and varying network topologies.
Progress in Dust Modelling, Global Dust Budgets, and Soil Organic Carbon Dynamics
Authors: Chen Weixiao , Meng Huan , Song Hongquan , Zheng Hui
Published: January 2022

Dust emission is an important corollary of the soil degradation process in arid and semi-arid areas worldwide. Soil organic carbon (SOC) is the main terrestrial pool in the carbon cycle, and dust emission redistributes SOC within terrestrial ecosystems and to the atmosphere and oceans. This redistribution plays an important role in the global carbon cycle. Herein, we present a systematic review of dust modelling, global dust budgets, and the effects of dust emission on SOC dynamics. Focusing on selected dust models developed in the past five decades at different spatio-temporal scales, we discuss the global dust sources, sinks, and budgets identified by these models and the effect of dust emissions on SOC dynamics. We obtain the following conclusions: (1) dust models have made considerable progress, but there are still some uncertainties; (2) a set of parameters should be developed for the use of dust models in different regions, and direct anthropogenic dust should be considered in dust emission estimations; and (3) the involvement of dust emission in the carbon cycle models is crucial for improving the accuracy of carbon assessment.
Assessment of Key Feeding Technologies and Land Use in Dairy Sheep Farms in Spain
Authors: Bastanchury-López María Teresa , De-Pablos-Heredero Carmen , Martín-Romo-Romero Santiago , García Antón
Published: January 2022

Familiar mixed dairy sheep farm is the most widespread system in the Mediterranean basin, in Latin America and in developing countries (85%). There is a strong lack of technological adoption in packages of feeding and land use in small-scale farms. To increase competitiveness, it would be of great interest to deepen the knowledge of how innovation was selected, adopted, and spread. The objective of this research was to select strategic feeding and land use technologies in familiar mixed dairy sheep systems and later assess dairy sheep farms in Spain. This objective was assessed by combining qualitative and quantitative methodologies. In the first stage, with the aim to identify and select the appropriate technologies, a panel of 107 experts in dairy sheep production was used. A questionnaire was applied to all of them with successive rounds using Delphi methodology. Later, these technologies were grouped by principal components analysis (PCA) and cluster analysis (CA). In a second stage the technological results from a random sample of 157 farms in the Center of Spain were collected. The technologies selected were linked to the technological adoption level of the farms in Castilla la Mancha by a multiple regression model. Ten technologies were selected by the 107 experts. Four factors were retained by PCA that explained at 67.11% of variance. The first factor is related to feeding strategies, the second to land use for livestock production, the third to efficient management of land resources or ecoefficiency and the fourth to by-products use. The expert evaluation was grouped in three clusters using the Ward’s method and the squared Euclidean distance measure, where the second showed higher values in the adoption level of each technology. The multiple regression model explained the relationship between the technologies and the technological level of the farms (R2 73.53%). The five technologies selected were: use of unifeed (1), supplemental feeding (5), grazing (6), raw materials production (7) and sustainable use of water and soil (10). These ten technologies identified can be directly extended to small-scale dairy farms from other countries in the Mediterranean basin and Latin America. This technological selection was supported from the broad and diverse panel of experts used. Besides, five technologies identified by the quantitative model will be able to be taken into account for the development of public innovation policies. They are direct technologies and easy to apply on the farm and seeking increased viability through innovation vs. intensification.
On the Syntax of Existential Sentences in Najdi Arabic
Authors: Alharbi Bader
Published: January 2022

The existential sentence is a noncanonical sentence type that is used crosslinguistically to assert the (non)existence of one or more entities. It consists of a set of syntactic items that includes an expletive, pivot, and coda. Two different syntactic analyses have been identified in the literature for the existential construction. The first type of analysis, the standard analysis, treats the existential sentence as a nonraising counterpart of copular sentences. In this analysis, both existential and copular sentences are derived from a single underlying structure, which takes the pivot as a subject and the coda as a predicate. The other type of analysis, the nonstandard analysis, treats the existential sentence differently from the copular sentence. In this analysis, the copular verb takes the pivot NP as its complement, and the coda is treated as an adjunct. The purpose of this paper is to examine the syntactic status of the three syntactic items, namely, the expletive fiih, the pivot NP, and the coda XP, in the existential construction in the dialect of Najdi Arabic (NA). Using the nonstandard analysis, I propose that the existential pronoun fiih is an NP merged in the Spec, vP, the pivot is an NP complement selected by a copular verb, and the coda is an adjunct that serves as either an internal or external modifier. This work about NA existentials may fruitfully contribute to the ongoing discussion on the syntax of existential constructions. Examining existential constructions in various unrelated languages may help obtain a better understanding of this interesting syntactic phenomenon, thereby enabling a more plausible analysis.
Genetic Diversity Analysis of Mitochondrial Cytb Gene, Phylogeny and Phylogeography of Protected Griffon Vulture (Gyps fulvus) from Serbia
Authors: Davidović Slobodan , Marinković Saša , Kukobat Mila , Mihajlović Milica , Tanasić Vanja , Hribšek Irena , Tanasković Marija , Stamenković-Radak Marina
Published: January 2022

Once a widespread and common species across the region of southeast Europe, the Griffon vulture is now confined to small and isolated populations across the Balkan Peninsula. The population from Serbia with 290 couples represents its biggest and most viable population that can serve as an important reservoir of genetic diversity from which the birds can be used for the region’s reintroduction or recolonization programs. To estimate the level of genetic diversity, the mitochondrial Cytb gene from 58 unrelated birds sampled during the marking in the nests was sequenced and compared to the homologous Griffon vulture sequences available in publicly accessible online databases. Phylogeographic analysis based on Cytb sequences showed that the most frequent haplotype is found in all Griffon vulture populations and that each population possesses private haplotypes. Our data suggest that the Griffon vulture population from Serbia should be used as a source population for restocking and reintroduction programs in the region. The observed genetic differentiation between the populations from the Iberian and Balkan Peninsulas suggest that the introduction of foreign birds from remote populations should be avoided and that birds from indigenous or neighboring populations, if available, should be used instead.
Reactions of 4H-1,2,6-Thiadiazine Sulfides
Authors: Kalogirou Andreas S. , Koutentis Panayiotis A.
Published: January 2022

3,5-Dichloro-4H-1,2,6-thiadiazin-4-one reacts with benzo[d]thiazole-2-thiol (1 equiv) and triethylamine (1 equiv) to give 3-(benzo[d]thiazol-2-ylthio)-5-chloro-4H-1,2,6-thiadiazin-4-one in 71% yield. The reactivity of this compound with methoxide is explored and compared with that of 3-chloro-5-(phenylthio)-4H-1,2,6-thiadiazin-4-one.
Analysis for DC and RF Characteristics Recessed-Gate GaN MOSFET Using Stacked TiO2/Si3N4 Dual-Layer Insulator
Authors: Min So-Ra , Cho Min-Su , Lee Sang-Ho , Park Jin , An Hee-Dae , Kim Geon-Uk , Yoon Young-Jun , Seo Jae-Hwa , Jang Jae-Won , Bae Jin-Hyuk , Lee Sin-Hyung , Kang In-Man
Published: January 2022

The self-heating effects (SHEs) on the electrical characteristics of the GaN MOSFETs with a stacked TiO2/Si3N4 dual-layer insulator are investigated by using rigorous TCAD simulations. To accurately analyze them, the GaN MOSFETs with Si3N4 single-layer insulator are conducted to the simulation works together. The stacked TiO2/Si3N4 GaN MOSFET has a maximum on-state current of 743.8 mA/mm, which is the improved value due to the larger oxide capacitance of TiO2/Si3N4 than that of a Si3N4 single-layer insulator. However, the electrical field and current density increased by the stacked TiO2/Si3N4 layers make the device’s temperature higher. That results in the degradation of the device’s performance. We simulated and analyzed the operation mechanisms of the GaN MOSFETs modulated by the SHEs in view of high-power and high-frequency characteristics. The maximum temperature inside the device was increased to 409.89 K by the SHEs. In this case, the stacked TiO2/Si3N4-based GaN MOSFETs had 25%-lower values for both the maximum on-state current and the maximum transconductance compared with the device where SHEs did not occur; Ron increased from 1.41 mΩ·cm2 to 2.56 mΩ·cm2, and the cut-off frequency was reduced by 26% from 5.45 GHz. Although the performance of the stacked TiO2/Si3N4-based GaN MOSFET is degraded by SHEs, it shows superior electrical performance than GaN MOSFETs with Si3N4 single-layer insulator.
Numerical Investigation of the Seismic Performance of Steel Frames with Energy-Dissipating Composite Walls
Authors: Wei Ding , Suizi Jia
Published: January 2022

To improve the seismic performance of steel frame buildings in rural areas, an energy-dissipating composite wall (EDCW) assembled from concrete-filled steel tubular columns and concrete sheet walls was designed. Cyclic loading tests were simulated using the finite element method (FEM) to analyse the seismic performance of the EDCW. The reliability of numerical modelling and analysis was verified by comparing the hysteretic curves obtained by the finite element model with those obtained by previous experiments. The EDCW was designed for installation in a two-storey steel frame, and the FEM was used to determine the seismic performance of the steel frame, including the deformation and failure characteristics, hysteresis curves, and skeleton curves. The numerical simulation results showed that the EDCW dissipated most of the seismic energy and thus substantially improved the seismic performance of the frame. The seismic performances of 16 frames were compared to investigate the effects of the span ratio of the steel frame to the EDCW, the installation location of the EDCW, and the stiffness of the steel frame on the seismic performance of the frame.
Application of Pre-Wetted High Titanium Heavy Slag Aggregate in Cement Concrete
Authors: Zhang Tao , Huang Bei
Published: January 2022

High titanium heavy slag is one kind of solid waste that exists in large amounts in the southwest of China. In this paper, this high titanium heavy slag is used as natural pre-wetted material in concrete because of its porous structure. Three kinds of aggregates are used in this concrete. The first one is natural limestone and river sand. The second one is dry slag fine aggregate and coarse aggregate. The third one is pre-wetted coarse slag aggregate and dry slag fine aggregate. The strength, dry shrinkage, autogenous shrinkage, relative humidity, pore size distribution, stress–strain relationship, micro-hardness and chloride penetration of concrete composed of the above three aggregates are tested in this study. The results show that pre-wetted slag aggregate is a suitable internal curing material. The concrete with pre-wetted slag aggregate shows higher strength, lower shrinkage and smaller porosity. The water absorbed in the slag aggregate can be released effectively to increase the relative humidity, accelerate hydration, improve porosity and increase the interface strength.
Fatigue Analysis of the Microturbine Rotor Disc Made of 7075 Aluminium Alloy Using a New Hybrid Calculation Method
Authors: Zych Paweł , Żywica Grzegorz
Published: January 2022

Today, where the production of any kind of device may have a negative impact on the environment, it is crucial to produce machines that are as efficient as possible but that can also be strong enough to withstand harsh operating conditions for a long time. That is why this paper raises the issue of the fatigue analysis of high-speed axial-flow microturbines whose components are made of commonly used 7075 aluminium alloy. The paper presents different methods that can be used to estimate and increase the fatigue life of a turbine disc. The object of study is a 10-kilowatt vapour microturbine. The various mechanical, flow and thermal loads that can occur during the operation of the microturbine have been analysed so that the most important ones can be taken into account in the final considerations. Stress calculations were performed using analytical equations, and the finite element method (FEM) was also used. Using the stresses obtained and material characteristics, fatigue analysis was conducted. Then, new hybrid calculation methods were proposed, taking into account both analytical and numerical approaches that do not require the use of ready-made programs dedicated to fatigue analysis. To verify these methods, calculations were performed for two rotor discs with different geometries. These methods can be used by both engineers and scientists in the design process of various microturbines when fatigue calculations are performed.
Influence of Friction Stir Process on the Physical, Microstructural, Corrosive, and Electrical Properties of an Al–Mg Alloy Modified with Ti–B Additives
Authors: Moustafa Essam B. , Alazwari Mashhour A. , Abushanab Waheed Sami , Ghandourah Emad Ismat , Mosleh Ahmed O. , Ahmed Haitham M. , Taha Mohamed A.
Published: January 2022

In this study, two successive methods were used to improve the grain structure and the mechanical and physical properties of Al 5052 aluminum alloy. The modifying elements, 0.99 wt.% of titanium (Ti) and 0.2 wt.% of boron (B), were added during the casting process. After solidification, single- and double-pass friction stir processing (FSP) were performed to achieve additional grain refinement and disperse the newly formed phases well. The addition of Ti–B modifiers significantly improved the mechanical and physical properties of the Al 5052 aluminum alloy. Nevertheless, only a 3% improvement in microhardness was achieved. The ultimate strength (US), yield strength (YS), and elastic modulus were investigated. In addition, the electrical conductivity was reduced by 56% compared to the base alloys. The effects of grain refinement on thermal expansion and corrosion rate were studied; the modified alloy with Ti–B in the as-cast state showed lower dimension stability than the samples treated with the FSP method. The grain refinement significantly affected the corrosion resistance; for example, single and double FSP passes reduced the corrosion rate by 11.4 times and 19.2 times, respectively. The successive FSP passes, resulting in a non-porous structure, increased the bulk density and formed precipitates with high bulk density.
Recent Advances in Imidazolium-Based Dicationic Ionic Liquids as Organocatalysts: A Mini-Review
Authors: Pandolfi Fabiana , Bortolami Martina , Feroci Marta , Fornari Anastasia , Scarano Vincenzo , Rocco Daniele
Published: January 2022

Imidazolium-based dicationic ionic liquids (DILs) are gaining considerable space in the field of organocatalysis mainly due to the opportunities in offering new possible applicable structural variations. In addition to the well-known variables which made the ionic liquids (ILs) famous as the type of cation and anion used, the nature of the molecular spacer moiety turns out a further possibility to improve some physicochemical properties, for example, solubility, acidity, electrochemical behavior, and so on. For this reason, this class of ionic liquids has been considered as possible competitors to their corresponding monocationic salts in replacing common catalysts in organic synthesis, particularly in cases in which their bidentate nature could positively affect the catalytic activity. This mini-review is intended to highlight the progress carried out in the last six years in the field of organocatalysis, including DILs as such and as hybrids with polymers, nanomaterials, and composites.
Assist-As-Needed Control Strategy of Bilateral Upper Limb Rehabilitation Robot Based on GMM
Authors: Li Maoqin , Zhang Jiaji , Zuo Guokun , Feng Guang , Zhang Xueliang
Published: January 2022

Robotic-assisted rehabilitation therapy has been shown to be effective in improving upper limb motor function and the daily behavior of patients with motor dysfunction. At present, the majority of upper limb rehabilitation robots can only move in the two-dimensional plane, and cannot adjust the assistance mode in real-time according to the patient’s rehabilitation needs. In this paper, according to the shortcomings of the current rehabilitation robot only moving in the two-dimensional plane, a type of bilateral mirror upper limb rehabilitation robot structure with the healthy side assisting the affected side is proposed. This can move in three-dimensional space. Additionally, an assist-as-needed (AAN) control strategy for upper limb rehabilitation training is proposed based on the bilateral upper limb rehabilitation robot. The control strategy adopts Gaussian Mixture Model (GMM) and impedance controller to maximize the patient’s rehabilitation effect. In the task’s design, there is no need to rely on the assistance of the therapist, only the patients who completed the task independently. GMM guides the rehabilitation robot to provide different assistance for the patients at different task stages and induces the patients to complete the rehabilitation training independently by judging the extent to which the patients can complete the task. Furthermore, in this paper, the effectiveness of the proposed control strategy was verified by three volunteers participating in a two-dimensional task. The experimental results show that the proposed AAN control strategy can effectively provide appropriate assistance according to the classification stage of the interaction between the patients and the rehabilitation robot, and thus, patients can better achieve the rehabilitation effect during the rehabilitation task as much as possible.
An Improved Deadbeat Current Controller of PMSM Based on Bilinear Discretization
Authors: Zhao Lei , Chen Zhen , Wang Haoyu , Li Li , Mao Xuefei , Li Zhen , Zhang Jiyang , Wu Dengyun
Published: January 2022

Based on the bilinear discretization mathematical model of permanent magnet synchronous motor (PMSM), an improved incremental deadbeat current prediction control algorithm is proposed. Aiming at the system instability caused by the forward Euler discretization method, this paper combines the deadbeat current prediction control and the improved bilinear discretization method to improve the system stability. Further, the proposed controller considers the two-beat delay of a digital system to make the mathematical model more accurate. Moreover, the proposed bilinear discretization predictive current controller is not affected by the permanent magnet flux of the motor. Then, the system stability conditions of the proposed controller are analyzed. The simulation and experimental results verify the feasibility and effectiveness of the proposed method.
The Effect of Rotating Speeds on the Cavitation Characteristics in Hydraulic Torque Converter
Authors: Guo Meng , Liu Cheng , Yan Qingdong , Wei Wei , Khoo Boo Cheong
Published: January 2022

Hydraulic torque converter is a kind of high speed rotating machine using viscosity hydraulic oil as working medium, and its internal flow field is very complex. Thereby cavitation can occur easily in the working process, resulting in severe degradation of torque converter performance, noise, vibration and even failure. In order to reveal the effect of rotating speeds on the cavitation characteristics, a full flow passage geometry and a computational fluid dynamics (CFD) model with cavitation were developed to analyze the flow behavior in the torque converter. The results show that cavitation occurs when the speed difference between pump and turbine exceeds 1400 rpm for the basic model torque converter, which could be used as a useful indicator for the occurrence and degree of severity of flow cavitation. The increase of pump rotating speed or the decrease of speed ratio will intensify cavitation, which reduces the hydraulic transmission capacity and efficiency by over 20%, and seriously alters the shape, size, vapor volume fraction and region of cavitation bubbles. In extreme cases, more than 80% of the area on the suction side of the stator blade could be covered by cavitation bubbles. Moreover, the increase of pump rotating speed also changes the critical cavitation number and extends the cavitation range towards high speed ratio conditions not previously affected. These findings can provide guidance on how to choose the operating conditions of the hydraulic torque converter and how to improve its hydrodynamic performance and stability.
Numerical Solutions to Wave Propagation and Heat Transfer Non-Linear PDEs by Using a Meshless Method
Authors: Flores Jesús , García Ángel , Negreanu Mihaela , Salete Eduardo , Ureña Francisco , Vargas Antonio M.
Published: January 2022

The applications of the Eikonal and stationary heat transfer equations in broad fields of science and engineering are the motivation to present an implementation, not only valid for structured domains but also for completely irregular domains, of the meshless Generalized Finite Difference Method (GFDM). In this paper, the fully non-linear Eikonal equation and the stationary heat transfer equation with variable thermal conductivity and source term are solved in 2D. The explicit formulae for derivatives are developed and applied to the equations in order to obtain the numerical schemes to be used. Moreover, the numerical values that approximate the functions for the considered domain are obtained. Numerous examples for both equations on irregular 2D domains are exposed to underline the effectiveness and practicality of the method.
Latin American Agri-Food Exports, 1994–2019: A Gravity Model Approach
Authors: Ayuda María-Isabel , Belloc Ignacio , Pinilla Vicente
Published: January 2022

This study analyses the causes of the strong growth in the agri-food exports of Latin America between 1994 and 2019. To do this, a series of gravity models are estimated, using as a dependent variable the agri-food exports of 15 Latin American countries to their 185 principal trading partners. The empirical specification is based on the gravity theory of trade, according to which, trade between two countries is determined by the size of both of their markets and their transport costs. Other variables have also been included, considering the theoretical foundations proposed for the gravity model. We initially used the PPML estimator since it is the method that provides estimates with the best properties. We later compared these results with those obtained through OLS and the Heckman selection model. Our findings show that the growth in agri-food exports is explained by factors of both supply and demand, but that the latter plays a more important role since we have obtained evidence of a reverse home-market effect. Furthermore, we can conclude that the creation of regional trade agreements, such as NAFTA, MERCOSUR, CACM, APEC, and TPP, has significantly favoured agri-food exports in the region.
IGA-Energetic BEM: An Effective Tool for the Numerical Solution of Wave Propagation Problems in Space-Time Domain
Authors: Aimi Alessandra , Boiardi Ariel Surya
Published: January 2022

The Energetic Boundary Element Method (BEM) is a recent discretization technique for the numerical solution of wave propagation problems, inside bounded domains or outside bounded obstacles. The differential model problem is converted into a Boundary Integral Equation (BIE) in the time domain, which is then written into an energy-dependent weak form successively discretized by a Galerkin-type approach. Taking into account the space-time model problem of 2D soft-scattering of acoustic waves by obstacles described by open arcs by B-spline (or NURBS) parametrizations, the aim of this paper is to introduce the powerful Isogeometric Analysis (IGA) approach into Energetic BEM for what concerns discretization in space variables. The same computational benefits already observed for IGA-BEM in the case of elliptic (i.e., static) problems, is emphasized here because it is gained at every step of the time-marching procedure. Numerical issues for an efficient integration of weakly singular kernels, related to the fundamental solution of the wave operator and dependent on the propagation wavefront, will be described. Effective numerical results will be given and discussed, showing, from a numerical point of view, convergence and accuracy of the proposed method, as well as the superiority of IGA-Energetic BEM compared to the standard version of the method, which employs classical Lagrangian basis functions.
The Projection of Gamification and Serious Games in the Learning of Mathematics Multi-Case Study of Secondary Schools in Italy
Authors: Malvasi Viviana , Gil-Quintana Javier , Bocciolesi Enrico
Published: January 2022

Our research was born with the objective of evaluating the level of gamification of high schools in Italy, specifically for mathematics, and the use of the serious game of chess as a resource for learning this discipline. The methodology is a mixed design, based on the combination of quantitative and qualitative techniques. Regarding the quantitative design, the instrument used was a questionnaire filled out by 4845 adolescents living in Italy. The qualitative methodology has focused on the analysis of the discourse of 12 in-depth interviews with mathematics teachers from high schools. Among the main results, we found that teachers, although unconsciously, apply gamification in classrooms (without having had any training about it) and, despite recognizing the mathematical benefits of chess, they do not use this game as a serious game. Our study confirms that gamification deserves more because of the benefits it brings, especially for a subject that scares students and demands greater motivation.
SinLU: Sinu-Sigmoidal Linear Unit
Authors: Paul Ashis , Bandyopadhyay Rajarshi , Yoon Jin Hee , Geem Zong Woo , Sarkar Ram
Published: January 2022

Non-linear activation functions are integral parts of deep neural architectures. Given the large and complex dataset of a neural network, its computational complexity and approximation capability can differ significantly based on what activation function is used. Parameterizing an activation function with the introduction of learnable parameters generally improves the performance. Herein, a novel activation function called Sinu-sigmoidal Linear Unit (or SinLU) is proposed. SinLU is formulated as SinLU(x)=(x+asinbx)·σ(x), where σ(x) is the sigmoid function. The proposed function incorporates the sine wave, allowing new functionalities over traditional linear unit activations. Two trainable parameters of this function control the participation of the sinusoidal nature in the function, and help to achieve an easily trainable, and fast converging function. The performance of the proposed SinLU is compared against widely used activation functions, such as ReLU, GELU and SiLU. We showed the robustness of the proposed activation function by conducting experiments in a wide array of domains, using multiple types of neural network-based models on some standard datasets. The use of sine wave with trainable parameters results in a better performance of SinLU than commonly used activation functions.
Adaptive Sliding Mode Control of Robot Manipulators with System Failures
Authors: Li Rui , Yang Liang , Chen Yong , Lai Guanyu
Published: January 2022

This paper presents a novel adaptive sliding mode controller for a class of robot manipulators with unknown disturbances and system failures, which can well achieve the asymptotic tracking, and avoid some possible singularity problems. A new virtual controller is designed such that the chosen Lyapunov function can be transformed into a non-Lipschitz function, based on which, the system states can arrive at the specified sliding surface within a finite time regardless of the existence of system failures/faults. By fusing an integral fast terminal nonsingular SMC and a robust adaptive technique, the tracking error can be steered into a preset range in a set time and some possible singularity problems are avoided elegantly. With our proposed scheme, the loss coefficient is well estimated, and the stability of the system can be guaranteed even in the presence of the total loss of actuator outputs. The experiment and simulation results are presented to illustrate the effectiveness of the proposed control scheme.
Improving Calculus Curriculum in Engineering Degrees: Implementation of Technological Applications
Authors: López-Díaz María Teresa , Peña Marta
Published: January 2022

The teaching of mathematics has always concerned all the professionals involved in engineering degrees. Curently students have less interest in these studies, what has caused an increase of this concern. The lack of awareness of students about the significance of mathematics in their careers, provoke the decrease of undergraduate students’ motivation, which derives in a low interest in engineering degrees. The aim of this work is that engineering students achieve a greater motivation and involvement in first academic courses, through the implementation of real and technological applications related to their degrees in the learning of mathematical concepts. To this end, the 2019/2020 and 2020/2021 academics years, the seminar “Applications of Multivariable Calculus in Engineering” has been held in Universitat Politècnica de Catalunya-BarcelonaTech (UPC), based on the teaching of Multivariable Calculus by the execution of real problems where calculus concepts are necessary to solve them. With the aim of analyzing students’ motivation and assessment of the seminar, anonymous surveys and personal interviews have been conducted. The number of attending students to the sessions in each academic year has been 16 and all of them have been participants in the surveys and interviews. The results show that students’ responses were generally positive and they agree that their motivation to the subject Multivariable Calculus has increased with the use of real applications of mathematics. The execution of practical problems with engineering applications improves the acquirement of mathematical concepts, what could imply an increase of students’ performance and a decrease of the dropout in the first academic courses of engineering degrees.