bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving Farmer Willingness to Participate in the Transfer of Land Rights in Rural China: A Preference-Based Income Distribution Scheme
Authors: Yan Lei , Lei Xubin , Hong Kairong , Li Hui , Chen Mengyuan
Published: March 2022

Promoting the transfer of rural land is an important way for many developing countries to improve the efficiency of rural land use and develop the rural economy. A reasonable income distribution scheme (IDS) is the key to enhancing farmer willingness to participate in the transfer of rural construction land use rights. However, little attention has been paid to farmers’ preference for the IDS of the transfer of rural collective construction land use rights. This research aims to detect the farmers’ preference for IDS in the process of rural collective land rights transfer. Based on the survey data of 489 farmers in Liuyang City, Hunan Province and Deqing County, Zhejiang Province, China, a random parameter Logit model is used to explore their preference for the IDS of the transfer of rural collective construction land use rights. The results show that, in general, the farmers focus on the income distribution ratio and pension in the IDS, which will significantly improve their utility. There are obvious regional differences in their preference for IDSs. For example, farmers in Liuyang prefer payment in shares, while those in Deqing prefer cash. Thus, the IDS for the transfer of rural collective construction land use rights should be based on the basic principle of ensuring fair land value-added income for the farmers, increased payment forms with social security functions, and reasonable IDSs in accord with the preferences of farmers in different regions, so as to enhance farmer willingness to participate.
Construction of Ecological and Recreation Patterns in Rural Landscape Space: A Case Study of the Dujiangyan Irrigation District in Chengdu, China
Authors: Dong Qidi , Wu Linjia , Cai Jun , Li Di , Chen Qibing
Published: March 2022

The rapid expansion of urbanization has promoted the prosperity of the economy and society but has also caused rural ecological problems. This study takes the Dujiangyan Irrigation District as an example, to construct ecological and recreation patterns, and it breaks through the pattern construction mode of using a single ecological factor that has been used in previous studies. We analyzed the impact of landscape connectivity and area thresholds at different scales on the selection of source areas, and integrated urban construction and human disturbance factors into resistance surface construction. Finally, a comprehensive landscape network combining “ecology and recreation” was determined through the minimum cumulative resistance model. Multiscale landscape connectivity analysis and area threshold setting greatly promoted the results of source identification. After optimization, we identified four ecological corridors and twenty-seven recreational corridors, and the regional landscape security pattern was significantly improved compared with the previous upper planning content. Therefore, this study provides a reference for regional long-term planning and has reference significance for the spatial protection and utilization of rapidly urbanizing areas.
Quantitative Identification of Rural Functions Based on Big Data: A Case Study of Dujiangyan Irrigation District in Chengdu
Authors: Dong Qidi , Cai Jun , Wu Linjia , Li Di , Chen Qibing
Published: March 2022

Urbanization increases the scales of urban spaces and the sizes of their populations, causing the functions in cities and towns to be in short supply. This study carries out functional space identification on the Dujiangyan elite irrigation area based on remote sensing data and point of interest (POI) data from Open Street Map (OSM), enabling the use of POI data to analyze rural functional spaces. Research and development and big data can greatly improve the accuracy of spatial function recognition, but research on rural spaces has limitations regarding the amount of available data. The Dujiangyan Irrigation District has low spatial aggregation levels for functions, scattered functions and linear distributions along roads. The mixing degrees of regional functions are low, the connections between functional elements are insufficient, and the comprehensive functional quality is low. The features of various functional elements in the region are significant, mostly in the discrete distribution mode, and functional compounding has become a trend. Therefore, it is necessary to integrate spatial resources and improve the centrality of cities and towns to realize the optimal allocation of resources and enable the development of surrounding cities and towns.
Artisanal Products and Land-Use Land-Cover Change in Indigenous Communities: The Case of Mezcal Production in Oaxaca, Mexico
Authors: Lira María G. , Davidson-Hunt Iain J. , Robson James P.
Published: March 2022

Artisanal products are considered an alternative to industrial production; however, upon entering global commodity markets, pressures are placed on the territories and customary governance of producer communities. Through the lenses of land system science and telecouplings, this paper examines the links connecting global markets and artisanal products, using the case of mezcal production in an Indigenous community in Oaxaca, Mexico, and the resulting impacts to LULC (land-use and land-cover) dynamics and associated governance. Data were collected through document review, semi-structured interviews, and LULC analysis comparing the years 1993, 2001, 2013, and 2019. Agave crops expanded from 6 to 14% during 1993–2001, stabilized through 2001–2013, and expanded from 14 to 22% during 2013–2019. Market dynamics played a crucial role in the resultant LULC changes, with the biggest impact on tropical dry forest (TDF). The LULC results were coupled with tequila markets during the first two periods, while the third period was linked to new mezcal markets. Our research shows how artisanal production can drive LULC changes. However, customary governance institutions can mediate the relationship between producers and markets to support more sustainable management of territorial resources, including TDF as an ecologically important but locally undervalued forest type.
Land Cover and Land Use Mapping of the East Asian Summer Monsoon Region from 1982 to 2015
Authors: He Yaqian , Oh Jieun , Lee Eungul , Kim Yaeone
Published: March 2022

Owing to the recent intensification of the East Asian summer monsoon, the frequency of floods and dry spells, which commonly affect more than one billion people, is continuously increasing. Thus, understanding the causes of changes in the EASM is paramount. Land cover and land use change can perturb a regional climate system through biogeophysical and biogeochemical processes. However, due to the scarcity of temporally continuous land cover and land use maps, the impact of land cover and land use change on the EASM is still not thoroughly explored. In the present study, this limitation was addressed via the production of annual land cover and land use maps of the East Asian summer monsoon region covering a period of 34 years (1982–2015). This was achieved through a random forest classification of phenological information derived from the Advanced Very High-Resolution Radiometer Global Inventory Modeling and Mapping Studies Normalized Difference Vegetation Index dataset and terrain information from the Advanced Land Observing Satellite World 3D—30 m Digital Surface Model data. Nine ecological zones were involved in the random forest classification and the classified map in 2015 was validated using very high-resolution images obtained from Google Earth. The overall accuracy (73%) of the classification map surpasses the Moderate Resolution Imaging Spectroradiometer and Global Land Surface Satellite land cover products for the same year by ~7% and 4%, respectively. According to our classified maps, croplands and forests significantly increased in the East Asian summer monsoon region from 1982 to 2015. The dominant transition in these three decades was from croplands to forests.
A Comparative Study on the Viability of Normal and Cancerous Cells upon Irradiation with a Steady Beam of THz Rays
Authors: Kovalevska Larysa , Golenkov Olexandr , Kulahina Yelyzaveta , Callender Todd , Sizov Fedir , Kashuba Elena
Published: March 2022

Terahertz (THz) electromagnetic radiation is commonly used in astronomy, security screening, imaging, and biomedicine, among other applications. Such approach has raised the question of the influence of THz irradiation on biological objects, especially the human body. However, the results obtained to date are quite controversial. Therefore, we performed a comparative study on the viability of normal cells and cancer cells upon irradiation with a steady beam of THz rays. We used human peripheral blood mononuclear cells and cancer cell lines. Primary human mononuclear blood cells (monocytes, and B-, and T-cells) showed an increased death rate, determined by cell counting and fluorescence microscopy, upon 0.14 THz irradiation. The effect of THz radiation was different among malignant cells of B- and T-cell origin (Ramos and Jurkat cells) and epithelial cancer cells (MCF7 and LNCaP). This was demonstrated by cell counting and by the alamarBlue assay. In conclusion, THz radiation can result in the death of human primary and malignant cells. However, the mechanism of this phenomenon is largely unknown. Hence, more work should be done to shed some light on the mechanism of action of THz irradiation in living organisms to enhance technologic developments.
Contribution of Hypoxic Exercise Testing to Predict High-Altitude Pathology: A Systematic Review
Authors: Georges Thomas , Menu Pierre , Le Blanc Camille , Ferreol Sophie , Dauty Marc , Fouasson-Chailloux Alban
Published: March 2022

Altitude travelers are exposed to high-altitude pathologies, which can be potentially serious. Individual susceptibility varies widely and this makes it difficult to predict who will develop these complications. The assessment of physiological adaptations to exercise performed in hypoxia has been proposed to help predict altitude sickness. The purpose of this review is to evaluate the contribution of hypoxic exercise testing, achieved in normobaric conditions, in the prediction of severe high-altitude pathology. We performed a systematic review using the databases PubMed, Science Direct and Embase in October 2021 to collect studies reporting physiological adaptations under hypoxic exercise testing and its interest in predicting high-altitude pathology. Eight studies were eligible, concerning 3558 patients with a mean age of 46.9 years old, and a simulated mean altitude reaching of 5092 m. 597 patients presented an acute mountain sickness during their altitude travels. Three different protocols of hypoxic exercise testing were used. Acute mountain sickness was defined using Hackett’s score or the Lake Louise score. Ventilatory and cardiac responses to hypoxia, desaturation in hypoxia, cerebral oxygenation, core temperature, variation in body mass index and some perceived sensations were the highlighted variables associated with acute mountain sickness. A decision algorithm based on hypoxic exercise tests was proposed by one team. Hypoxic exercise testing provides promising information to help predict altitude complications. Its interest should be confirmed by different teams.
The Role of Lifestyle Intervention, in Addition to Drugs, for Diabetic Kidney Disease with Sarcopenic Obesity
Authors: Chen Shu-Hua , Liang Yao-Jen
Published: March 2022

Diabetic kidney disease is the leading cause of end-stage renal disease in developing and developed countries. The growing prevalence and clinical challenges of sarcopenic obesity have been associated with the frailty and disability of diabetic kidney disease. It has been reported that insulin resistance, chronic inflammation, enhanced oxidative stress and lipotoxicity contribute to the pathophysiology of muscle loss and visceral fat accumulation. Sarcopenic obesity, which is diagnosed with dual-energy X-ray absorptiometry, is associated with worse outcomes in kidney disease. Growing evidence indicates that adherence to healthy lifestyles, including low protein diet, proper carbohydrate control, vitamin D supplement, and regular physical training, has been shown to improve clinical prognosis. Based on the higher risk of sarcopenic-obesity-related renal function decline, it has led to the exploration and investigation of the pathophysiology, clinical aspects, and novel approach of these controversial issues in daily practice.
Kinetics of Heterogeneous Background in Stargardt’s Disease over Time
Authors: Rodríguez-Bocanegra Eduardo , Biarnés Marc , Garcia Míriam , Ferraro Lucía Lee , Fischer Manuel Dominik , Monés Jordi
Published: March 2022

Stargardt’s disease (STGD1) is caused by mutations in the ABCA4 gene. Different lesions characterised by decreased autofluorescence levels are found in fundus autofluorescence (FAF) from STGD1 patients and could be used as outcome indicators for disease progression. We investigated the fate of foci with reduced autofluorescence (FRA) within the heterogeneous background of STGD1 patients using FAF imaging. Genetically confirmed STGD1 patients presenting heterogeneous background autofluorescence on high-quality FAF images at a minimum of two visits at least 12 months apart were chosen. A grid centred on the fovea was used to define five different zones. Within each zone, five FRA were randomly selected for each eye. The eccentricity of foci was determined at different time points for each patient. Analysis of 175 randomly chosen FRA showed consistent centrifugal displacement over time, most notably in eyes showing areas with definitely decreased autofluorescence. Interestingly, FRA did not leave an area of hypo-autofluorescence on FAF in locations where they were previously located. These findings may help to better understand STGD1 progression, improve FAF interpretation, and shed light on the nature of heterogeneous background.
In Silico Screening for Pesticide Candidates against the Desert Locust Schistocerca gregaria
Authors: Jackson Graham E. , Gäde Gerd , Marco Heather G.
Published: March 2022

Adipokinetic hormone (AKH) is one of the most important metabolic neuropeptides in insects, with actions similar to glucagon in vertebrates. AKH regulates carbohydrate and fat metabolism by mobilizing trehalose and diacylglycerol into circulation from glycogen and triacylglycerol stores, respectively, in the fat body. The short peptide (8 to 10 amino acids long) exerts its function by binding to a rhodopsin-like G protein-coupled receptor located in the cell membrane of the fat body. The AKH receptor (AKHR) is, thus, a potential target for the development of novel specific (peptide) mimetics to control pest insects, such as locusts, which are feared for their prolific breeding, swarm-forming behavior and voracious appetite. Previously, we proposed a model of the interaction between the three endogenous AKHs of the desert locust, Schistocerca gregaria, and the cognate AKHR (Jackson et al., Peer J. 7, e7514, 2019). In the current study we have performed in silico screening of two databases (NCI Open 2012 library and Zinc20) to identify compounds which may fit the endogenous Schgr-AKH-II binding site on the AKHR of S. gregaria. In all, 354 compounds were found to fit the binding site with glide scores < −8. Using the glide scores and binding energies, 7 docked compounds were selected for molecular dynamic simulation in a phosphatidylcholine membrane. Of these 7 compounds, 4 had binding energies which would allow them to compete with Schgr-AKH-II for the receptor binding site and so are proposed as agonistic ligand candidates. One of the ligands, ZINC000257251537, was tested in a homospecific in vivo biological assay and found to have significant antagonistic activity.
Wear Property and Wear Mechanisms of High-Manganese Austenitic Hadfield Steel in Dry Reciprocal Sliding
Authors: Luo Quanshun , Zhu Jingzhi
Published: March 2022

This paper reports the sliding wear properties and wear mechanisms of Hadfield high-Mn austenitic steel in a dry-sliding reciprocal tribotest against a WC counterpart. The associated wear mechanisms were studied through extensive characterisation of the obtained worn surface using analytical SEM, TEM, XRD and micro-hardness test. The tribotest revealed a coefficient of wear in the scale of 10−14 m3·N−1·m−1 and a coefficient of friction of 0.5–0.6. The steel encountered severe plastic deformation beneath the worn surface leading to a gradient of hardness profile, including the extreme hardening of the worn surface up to HV0.1 8.2 GPa. Despite the severe deformation and significant strain hardening, the steel still retained its austenitic structure without any detectable martensite. The combined surface and cross-sectional microscopic observations and extensive analysis of XRD peak breadth revealed the formation of nano-heterogeneous microstructure including nano-laminate, nanotwins and nanocrystalline beneath the worn surface. Spalling wear was found as the predominant wear mechanism. The spalling wear was caused by the embrittlement of the extremely hardened and nanocrystallised worn surface. Tribo-oxidation was also observed in the resultant wear debris.
Improving the Endoprosthesis Design and the Postoperative Therapy as a Means of Reducing Complications Risks after Total Hip Arthroplasty
Authors: Popov Valentin L. , Poliakov Aleksandr M. , Pakhaliuk Vladimir I.
Published: March 2022

One of the most high-tech, efficient and reliable surgical procedures is Total Hip Arthroplasty (THA). Due to the increase in average life expectancy, it is especially relevant for older people suffering from chronic joint disease, allowing them to return to an active lifestyle. However, the rejuvenation of such a severe joint disease as osteoarthritis requires the search for new solutions that increase the lifespan of a Total Hip Replacement (THR). Current trends in the development of this area are primarily focused on the creation of new materials used in THR and methods for their processing that meet the requirements of biocompatibility, long-term strength, wear resistance and the absence of an immune system response aimed at rejection. This study is devoted to the substantiation of one of the possible approaches to increase the reliability and durability of THR, based on the improvement of the implant design and postoperative rehabilitation technology, potentially reducing the risk of complications in the postoperative period.
Analysis of Grooves Used for Bearing Lubrication Efficiency Enhancement under Multiple Parameter Coupling
Authors: Wang Chao , Wang Mingkai , Zhu Linbo
Published: March 2022

Adding axial groove structures to the surface of bearing inner ring is an effective way to enhance the bearing lubrication efficiency. In this paper, the angular contact ball bearing H7006C was taken as the research object, and through visual simulations and quantitative experiments, systematic analyses and discussions were carried out to find out the relationship between groove-enhancing performance and working conditions. Firstly, simulation models of standard bearing and groove-added bearing were established. By combining the Volume of Fluid (VOF) model, the enhancing mechanism of grooves was found. Secondly, the trend of groove-enhancing performance with the change of rotation speed was studied through simulations and quantitative experiments. On this basis, through multiple parameter coupling, the effects of oil supply amount and nozzle diameter on the groove performance were discussed. The results show that the bottom oil layer is the key for grooves to achieve the lubrication efficiency enhancement, and its distribution can reflect the groove-enhancing performance. The groove width that best adapts to the change of working conditions increases with the increase of oil supply amount and nozzle diameter. To maintain the stability of bottom oil layer, the nozzle diameter should be larger than the groove width. This research is of great significance to the application of grooves in the lubrication efficiency enhancement of high-speed bearing.
Investigation on Deformation Behavior in the Surface of Metal Foil with Ultrasonic Vibration-Assisted Micro-Forging
Authors: Yin Zidong , Yang Ming
Published: March 2022

Excitation of the acoustic field, leading to the Blaha effect, significantly affects the plasticity of a material. In the micro-forming field, the so-called impact effect is found to generate a larger amount of dislocation and produce greater plastic deformation than acoustic softening. In this study, the mechanism of deformation in the surface of the material with ultrasonic vibration assistance was investigated and compared with that in the bulk. Forging tests using a newly developed ultrasonic vibrator were carried out on pure Cu foils with various process conditions. The longitudinal vibration frequency of the ultrasonic transducer was 60 ± 2 kHz, and the vibration amplitude was in an adjustable range of 0~6 μm. Forging tests were carried out at different amplitudes. The result shows that acoustic softening and the impact effect could be separated by an oscilloscope in the micro-forging system. The difference in deformation on the surface asperity caused by acoustic softening and the impact effect is discussed. Compared to acoustic softening, which has a limited effect on the deformation of the surface asperity, the impact effect could create more plastic deformation on the surface asperity. Therefore, the reduction in the surface roughness would increase after the impact effect occurs. In addition, to confirm the mechanism of acoustic softening and the impact effect, the microstructural evolution of specimens, at the surface scale and inner scale, was investigated by electron backscatter diffraction (EBSD). It was found that acoustic softening could create more grain refinement, and with the amplitude increasing, the impact effect would oppositely cause the surface grains to grow. In this study, the mechanism of how the impact effect and acoustic softening affect the deformation behavior of the surface asperity was investigated.
Microscopic Understanding of the Growth and Structural Evolution of Narrow Bandgap III–V Nanostructures
Authors: Zhang Leilei , Li Xing , Cheng Shaobo , Shan Chongxin
Published: March 2022

III–V group nanomaterials with a narrow bandgap have been demonstrated to be promising building blocks in future electronic and optoelectronic devices. Thus, revealing the underlying structural evolutions under various external stimuli is quite necessary. To present a clear view about the structure–property relationship of III–V nanowires (NWs), this review mainly focuses on key procedures involved in the synthesis, fabrication, and application of III–V materials-based devices. We summarized the influence of synthesis methods on the nanostructures (NWs, nanodots and nanosheets) and presented the role of catalyst/droplet on their synthesis process through in situ techniques. To provide valuable guidance for device design, we further summarize the influence of structural parameters (phase, defects and orientation) on their electrical, optical, mechanical and electromechanical properties. Moreover, the dissolution and contact formation processes under heat, electric field and ionic water environments are further demonstrated at the atomic level for the evaluation of structural stability of III–V NWs. Finally, the promising applications of III–V materials in the energy-storage field are introduced.
Bonding Behaviour of Steel Fibres in UHPFRC Based on Alkali-Activated Slag
Authors: Wetzel Alexander , Göbel Daniela , Schleiting Maximilian , Wiemer Niels , Middendorf Bernhard
Published: March 2022

The mechanical performance of fibre-reinforced ultra-high-performance concrete based on alkali-activated slag was investigated, concentrating on the use of steel fibres. The flexural strength is slightly higher compared to the UHPC based on Ordinary Portland Cement (OPC) as the binder. Correlating the flexural strength test with multiple fibre-pullout tests, an increase in the bonding behaviour at the interfacial-transition zone of the AAM-UHPC was found compared to the OPC-UHPC. Microstructural investigations on the fibres after storage in an artificial pore solution and a potassium waterglass indicated a dissolution of the metallic surface. This occurred more strongly with the potassium waterglass, which was used as an activator solution in the case of the AAM-UHPC. From this, it can be assumed that the stronger bond results from this initial etching for steel fibres in the AAM-UHPC compared to the OPC-UHPC. The difference in the bond strength of both fibre types, the brass-coated steel fibres and the stainless-steel fibres, was rather low for the AAM-UHPC compared to the OPC-UHPC.
Studies on Cement Pastes Exposed to Water and Solutions of Biological Waste
Authors: Sujak Agnieszka , Pyzalski Michał , Durczak Karol , Brylewski Tomasz , Murzyn Paweł , Pilarski Krzysztof
Published: March 2022

The paper presents studies on the early stages of biological corrosion of ordinary Portland cements (OPC) subjected to the reactive media from the agricultural industry. For ten months, cement pastes of CEM I type with various chemical compositions were exposed to pig slurry, and water was used as a reference. The phase composition and structure of hydrating cement pastes were characterized by X-ray diffraction (XRD), thermal analysis (DTA/TG/DTG/EGA), and infrared spectroscopy (FT-IR). The mechanical strength of the cement pastes was examined. A 10 to 16% decrease in the mechanical strength of the samples subjected to pig slurry was observed. The results indicated the presence of thaumasite (C3S·CO2·SO3·15H2O) as a biological corrosion product, likely formed by the reaction of cement components with living matter resulting from the presence of bacteria in pig slurry. Apart from thaumasite, portlandite (Ca(OH)2)—the product of hydration—as well as ettringite (C3A·3CaSO4·32H2O) were also observed. The study showed the increase in the calcium carbonate (CaCO3) phase. The occurrence of unreacted phases of cement clinker, i.e., dicalcium silicate (C2S) and tricalcium aluminate (C3A), in the samples was confirmed. The presence of thaumasite phase and the exposure condition-dependent disappearance of CSH phase (calcium silicate hydrate), resulting from the hydration of the cements, were demonstrated.
Application of ANN for Analysis of Hole Accuracy and Drilling Temperature When Drilling CFRP/Ti Alloy Stacks
Authors: Kolesnyk Vitalii , Peterka Jozef , Alekseev Oleksandr , Neshta Anna , Xu Jinyang , Lysenko Bohdan , Sahul Martin , Martinovič Jozef , Hrbal Jakub
Published: March 2022

Drilling of Carbon Fiber-Reinforced Plastic/Titanium alloy (CFRP/Ti) stacks represents one of the most widely used machining methods for making holes to fasten assemblies in civil aircraft. However, poor machinability of CFRP/Ti stacks in combination with the inhomogeneous behavior of CFRP and Ti alloy face manufacturing and scientific community with a problem of defining significant factors and conditions for ensuring hole quality in the CFRP/Ti alloy stacks. Herein, we investigate the effects of drilling parameters on drilling temperature and hole quality in CFRP/Ti alloy stacks by applying an artificial neuron network (ANN). We varied cutting speed, feed rate, and time delay factors according to the factorial design L9 Taguchi orthogonal array and measured the drilling temperature, hole diameter, and out of roundness by using a thermocouple and coordinate measuring machine methods for ANN analysis. The results show that the drilling temperature was sensitive to the effect of stack material layer, cutting speed, and time delay factors. The hole diameter was mainly affected by feed, stack material layer, and time delay, while out of roundness was influenced by the time delay, stack material layer, and cutting speed. Overall, ANN can be used for the identification of the drilling parameters–hole quality relationship.
Evolutionary Analysis of Heterogeneous Granite Microcracks Based on Digital Image Processing in Grain-Block Model
Authors: Liu Guanlin , Chen Youliang , Du Xi , Wang Suran , Fernández-Steeger Tomás Manuel
Published: March 2022

Rocks are natural materials with a heterogeneous microstructure, and the heterogeneity of the microstructure plays a crucial role in the evolution of microcracks during the compression process. A numerical model of a rock with a heterogeneous structure under compression is developed by digital image processing techniques and the discrete element method. On the grain scale, the damage mechanism and microcrack characteristics of a heterogeneous Biotite granite under compression fracture are investigated. First, the process of constructing a digital image-based heterogeneous grain model is described. The microscopic characteristics of geometric heterogeneity, elastic heterogeneity, and contact heterogeneity are all considered in the numerical model. Then, the model is calibrated according to the macroscopic properties of biotite granite obtained in the laboratory, and the numerically simulated microcrack cracking processes and damage modes are obtained with a high degree of agreement compared to the experiments. Numerical simulations have shown the following: (1) Microcracking occurs first at the weak side of the grain boundaries, and the appearance of intragranular shear cracks indicates that the rock has reached its peak strength. (2) The stress concentration caused by the heterogeneity of the microstructure is an essential factor that causes rock cracks and induces rupture. Intragranular cracks occur successively in quartz, feldspar (plagioclase), and biotite, with far more intragranular cracks in quartz and feldspar (plagioclase) than in biotite. (3) Microcracking in quartz occurs as clusters, fork and fracture features, and in feldspar (plagioclase) it tends to cause penetration microcracking, which usually surrounds or terminates at the biotite. (4) As the confining pressure increases, the tensile break between the grains is suppressed and the number of shear cracks increases. At the macro level, the rock failure mode of the numerical model changes from split damage to shear destruction, which is consistent with the law shown in laboratory experiments.
A Novel Process to Recover Gypsum from Phosphogypsum
Authors: Xiao Junhui , Lu Tao , Zhuang Yuanfa , Jin Huang
Published: March 2022

In this study, we investigated a coarse phosphogypsum containing 49.63% SO3, 41.41% CaO, 10.68%, 4.47% SiO2, 1.28% P2O5, 0.11% F, CaSO4·2H2O purity of 80.65%, and whiteness of 27.68. Phosphogypsum contains calcium sulfate dehydrate as the main mineral, with small amounts of brushite, quartz, muscovite, and zoisite. Harmful elements, such as silicon, phosphorus, and fluorine, are mainly concentrated in the +0.15 mm and −0.025 mm fraction, which can be pre-selected and removed by the grading method to further increase the CaSO4·2H2O content. Gypsum was recovered using a direct flotation method, which included one roughing, one scavenging, and two cleaning operations, from −0.15 mm to +0.025 mm. The test results show that a gypsum concentrate with a CaSO4·2H2O purity of 98.94%, CaSO4·2H2O recovery of 80.02%, and whiteness of 37.05 was achieved. The main mineral in the gypsum concentrate was gypsum, and limited amounts of muscovite and zoisite entered the gypsum concentrate because of the mechanical entrainment of the flotation process.
Incorporation of Optical Density into the Blending Design for a Biocement Solution
Authors: Fukue Masaharu , Lechowicz Zbigniew , Fujimori Yuichi , Emori Kentaro , Mulligan Catherine N.
Published: March 2022

The engineering practices for applying the microbial precipitation of carbonates require a design of the blending biocement solution (BCS). The BCS is usually blended with concentrated strains NO-A10, reaction media, such as urea and CaCl2, and a solvent, i.e., water or seawater. To characterize the BCS, the unknown microbial characteristics, such as the cell viability, are complex factors. Therefore, the optical density (OD) was redefined as Rcv OD*, in which OD* was the tentative OD of the BCS used and Rcv was the conversion rate concerning the cell viability. To determine Rcv values, a standard precipitation curve based on the precipitation rate at 24 h was determined. It was found that the curve was expressed by λ1 OD+ λ2 OD2, in which λ1 and λ2 were 8.46 M and −17.633 M, respectively. With this, the Rcv and OD values of unknown BCS were estimated from the results of precipitation tests using arbitrary OD* values. By extending the testing time, the second order term of OD or OD* was negligible. Accordingly, the precipitation amount is expressed as 8.46 OD, in which the OD can be estimated by precipitation tests using arbitrary OD* values of BCSs. Unless the Ca2+ value is dominant, the optimum blending of BCS can be determined by OD. Thus, it is concluded that the blending design of BCS is achieved using 8.46 OD, or 8.46 Rcv OD*, and the standard precipitation curve was defined in this study.
A New Method for the Calculation of Characteristics of Disc Springs with Trapezoidal Cross-Sections and Rounded Edges
Authors: Leininger Dominik Sebastian , Geilen Max Benedikt , Klein Marcus , Oechsner Matthias
Published: March 2022

In the European standards specifying disc spring manufacturing, geometry, shape and characteristic, an edge rounding is prescribed. Common methods for the calculation of disc spring characteristics, even in these standards, are based on a rectangular cross-section. This discrepancy can lead to a considerable divergence of the computed characteristic from the characteristic determined by testing. In literature, this divergence has not yet been examined with regard to rounded edges. In this paper, a new method addressing this problem is introduced. For this purpose, the geometry of idealized disc springs is parameterized. Based on four edge radii and two angles of the inner and outer faces, equations to compute the initial cone angle and the lever arm are introduced. These equations are used to formulate an algorithm to adapt other computation methods to non-rectangular cross-sections and rounded edges. The method is applied to the formulas by Almen–Laszlo, Curti–Orlando, Zheng and those by Kobelev. FE simulations of disc springs with rounded edges and a non-rectangular cross-section were used to verify the new formulas. The results show that the introduced method can be applied to known characteristic computation methods and result in a model expansion taking cross-section variations into account. The adjusted characteristics show more accurate alignment to the FE simulation for the cross-section variations investigated. These findings not only close the geometric gap between the manufacturing guidelines and the computation on an analytical basis, they also define a new parameter space for designs of disc springs and a corresponding force computation method to optimize spring characteristics.
Cross-Sectional Analysis of the Resistance of RC Members Subjected to Bending with/without Axial Force
Authors: Lechman Marek
Published: March 2022

This paper deals with the cross-sectional analysis of the resistance of RC members subjected to a bending moment with or without axial forces. To determine section resistance, the nonlinear material law for concrete in compression is assumed according to Eurocode 2, taking into account the effect of concrete softening. It adequately describes the concrete behavior of RC members up to failure. The idealized stress–strain relation for the reinforcing steel is assumed. For the ring cross-section subjected to bending with axial force and for areas weakened by an opening, normalized resistances have been derived by integrating corresponding equilibrium equations. They are presented in the form of interaction curves and compared with the results of testing conducted on RC eccentrically loaded columns. Furthermore, the ultimate normalized bending moment has been derived for the RC rectangle subjected to bending without axial force. It was applied to the cross-sectional analysis of steel and concrete composite beams consisting of the RC rectangular core located inside a reversed TT-welded profile. Comparative analysis indicated good agreements between the proposed section models and experimental data. The objective of the paper is the dimensioning optimization of the considered cross-sections with the fulfillment of structural safety requirements.
Contribution to Understanding of Synergy between Red Mud and Common Supplementary Cementitious Materials
Authors: Vladić Kancir Ivana , Serdar Marijana
Published: March 2022

Recently, much attention has been paid to the reuse of bauxite residues from alumina production, also known as red mud, in the cement industry. Red mud bears the potential to improve concrete properties due to its favourable chemical composition and particle size. In this work, the synergy between locally available red mud and common supplementary cementitious materials such as fly ash, slag, calcined clay and limestone in cement mixes is investigated. All materials used were sourced from the immediate vicinity of the cement plant. The study of synergy involved the evaluation of the individual chemical reactivity of each material using the R3 test by isothermal calorimetry as well as their joint contribution to the heat of hydration and the composition of the reaction products of the paste and the compressive strength of the mortar. The results show how, by understanding the synergy between the materials, a higher level of cement substitutions can be achieved without compromising the mechanical properties of the mortar.
Factors Influencing the Properties of Extrusion-Based 3D-Printed Alkali-Activated Fly Ash-Slag Mortar
Authors: Yuan Qiang , Gao Chao , Huang Tingjie , Zuo Shenghao , Yao Hao , Zhang Kai , Huang Yanling , Liu Jing
Published: March 2022

The mix proportioning of extrusion-based 3D-printed cementitious material should balance printability and hardened properties. This paper investigated the effects of three key mix proportion parameters of 3D-printed alkali-activated fly ash/slag (3D-AAFS) mortar, i.e., the sand to binder (s/b) ratio, fly ash/ground granulated blast-furnace slag (FA/GGBS) ratio, and silicate modulus (Ms) of the activator, on extrudability, buildability, interlayer strength, and drying shrinkage. The results showed that the loss of extrudability and the development of buildability were accelerated by increasing the s/b ratio, decreasing the FA/GGBS ratio, or using a lower Ms activator. A rise in the s/b ratio improved the interlayer strength and reduces the drying shrinkage. Although increasing the FA/GGBS mass ratio from 1 to 3 led to a reduction of 35% in the interlayer bond strength, it decreased the shrinkage strain by half. A larger silicate modulus was beneficial to the interlayer bond strength, but it made shrinkage more serious. Moreover, a simple centroid design method was developed for optimizing the mix proportion of 3D-AAFS mortar to simultaneously meet the requirements of printability and hardened properties.
Performance Evaluation of Tunnel-Slag-Improved High Liquid Limit Soil in Subgrade: A Case Study
Authors: Zheng Xiaomeng , Shao Zhushan , Zhao Nannan , Li Chenglong , Wu Kui
Published: March 2022

The application of tunnel-slag-improved high liquid limit soil as filling materials in subgrade is a green environmental technology. This study explored the influence of tunnel slag mixing on the physical and mechanical properties of improved soils, based on the engineering background of Liyu highway, Guangxi Province, China. Firstly, the optimal moisture content, maximum dry density, shear strength parameters, California bearing ratio (CBR) and resilience modulus of plain and tunnel-slag-improved high liquid limit soils were experimentally determined. Results showed that the direct utilization of untreated soil was unacceptable in subgrade practice. A significant enhancement of integrity of high liquid limit soils could be obtained by tunnel slag mixing, and the value of 15% was determined as the optimal tunnel slag content in soils, leading to improved soil performance meeting the specification requirements. Then, numerical simulation on the stability of subgrade slope of tunnel-slag-improved soils at the content of 15% was conducted. It also reported the long-term subgrade settlements. The feasibility of utilization of tunnel slag in improving properties of high liquid limit soils was further validated. Finally, a good application of tunnel-slag-improved high liquid limit soil as subgrade filling materials in Liyu highway was achieved. The findings in this study could provide useful guidance for similar engineering.
Integrated Conceptual Mechatronic Design of a Delta Robot
Authors: Portillo-Vélez Rogelio de Jesús , Burgos-Castro Iván Andrés , Vásquez-Santacruz José Alejandro , Marín-Urías Luis Felipe
Published: March 2022

In this paper, a conceptual design of a Delta robot is developed by means of a mechatronic design methodology. A fully integrated conceptual design, clarifying the recurrence of the conceptual design process using black-box/white-box analysis, is presented using the Model Based Systems Engineering (MBSE) paradigm and the SysML language as the formal modeling tool. Multiple designs proposals are then evaluated by the non-linear Choquet integral in order to choose the most appropriate according to a multicriteria requirement. For a preliminary conceptual design, structural parameters for the Delta robot are determined by defining and solving a nonlinear constrained optimization problem, which considers the kinematic model of the robot maximizing its workspace. Both the decision making and the optimization problem are integrated and automated into a common software framework for the design process, by using a standard genetic algorithm and Monte Carlo method to set the optimized conceptual design to be rendered in Computer Aided Design (CAD) software and in a physical prototype, satisfying the technical specifications.
A Novel Experimental Method for Identifying the Flux Linkage Map of a High-Power Medium-Voltage Electrically Excited Synchronous Machine with Double Stator Winding
Authors: Turk Nikola , Cikač Dominik , Bulić Neven , Barbanti Stefano
Published: March 2022

Accurate knowledge of the magnitude and position of the magnetic flux is essential for implementing field-oriented control (FOC) and achieving high-performance behaviour of AC drives. For estimating the flux in a wide range of speeds, so-called hybrid flux estimators, which are a combination of current-model and voltage-model based estimators, are usually used. Since the inductances are used as parameters in the current model, knowledge of the actual flux–current relationship, i.e., of the actual flux linkage map, is inevitable. In this paper, a novel experimental method for identifying the flux linkage map of an electrically excited synchronous machine (EESM) with double stator winding is proposed, which, unlike most existing experimental methods, does not require an additional machine to be used as a load. The flux is determined for different operating points to which the unloaded and sped-up machine is brought to by injecting d- and q-axis stator current components, whereby the current controllers are used to keep them constant for a certain operating point. The proposed method has been used to identify the flux linkage map of a medium-voltage EESM with double stator winding. A more than acceptable accuracy confirmed by comparison with three different analytical methods, together with the fact that it does not require a complex experimental setup, makes the proposed method suitable for the identification of a machine’s flux linkage map in an industrial environment.
Comparison and Verification of Dynamic Simulations and Experiments for a Modified Spur Gear Pair
Authors: Wang Zhi-Gen , Lo Chien-Cheng , Chen Yi-Cheng
Published: March 2022

In this study, static and dynamic analyses of a spur gear pair with linear tip relief and longitudinal crowning were performed. Dynamic experiments were conducted to compare and verify the dynamic analysis results. On the basis of the theory of gearing, the mathematical model of a modified spur gear pair was established. In addition, a finite element mesh generation program was developed according to the mathematical model. Finite element analysis was applied to calculate the contact stress, contact patterns, and mesh stiffness of the gear pair. Moreover, a dynamic analysis was performed to predict the dynamic transmission error (DTE) at various speeds and loads. Dynamic experiments were performed on the spur gear pair by using a gear dynamic tester. Accelerometers were mounted on the gear pair to record the vibrations during gear meshing. The experimental DTE was calculated and compared with the simulated DTE to verify the prediction of the vibration performance of the spur gear pair under different rotational conditions.
Mathematical Modeling and Simulation of Suspended Equipment Impact on Car Body Modes
Authors: Sharma Sunil Kumar , Lee Jaesun , Jang Hong-Lae
Published: March 2022

A passenger railway vehicle’s lightweight design is an efficient technique of reducing energy consumption and dynamic forces between wheel and rail. However, light design results in resonant vibration in a car body. To restrain resonant vibration, a correlation between the suspended equipment variables and the car body’s modal frequency was investigated in this paper. A rigid–flexible general model was developed to examine the impacts of different equipment suspended under the chassis based on mass, location, and frequency on the car body mode. In addition, the numerical model is validated through the experimental result in terms of ride quality. The results demonstrate that the underframe equipment’s suspension characteristics have a significant impact on the mode of the car body, particularly the frequency of the first bending mode. Equipment with a considerable mass should be suspended near the center of the car body to optimize the frequency of the car body’s high-frequency bending. The weight of the equipment has a significant impact on the car body’s first bending frequency. The frequency of heavy equipment should be low enough to promote high-frequency transmissibility and improve the vibration characteristics of the car body.
The Impact of the Wiener Process on the Analytical Solutions of the Stochastic (2+1)-Dimensional Breaking Soliton Equation by Using Tanh–Coth Method
Authors: Al-Askar Farah M. , Mohammed Wael W. , Albalahi Abeer M. , El-Morshedy Mahmoud
Published: March 2022

The stochastic (2+1)-dimensional breaking soliton equation (SBSE) is considered in this article, which is forced by the Wiener process. To attain the analytical stochastic solutions such as the polynomials, hyperbolic and trigonometric functions of the SBSE, we use the tanh–coth method. The results provided here extended earlier results. In addition, we utilize Matlab tools to plot 2D and 3D graphs of analytical stochastic solutions derived here to show the effect of the Wiener process on the solutions of the breaking soliton equation.