bluuebunny/crossref_metadata_2025 huggingface dataset:
An Investigation of Various Controller Designs for Multi-Link Robotic System (Robogymnast)
Authors: Abdul samad Bdereddin , Mohamed Mahmoud , Anayi Fatih , Melikhov Yevgen
Published: September 2022

An approach to controlling the three-link Robogymnast robotic gymnast and assessing stability is proposed and examined. In the study, a conventionally configured linear quadratic regulator is applied and compared with a fuzzy logic linear quadratic regulator hybrid approach for stabilising the Robogymnast. The Robogymnast is designed to replicate the movement of a human as they hang with both hands holding the high bar and then work to wing up into a handstand, still gripping the bar. The system, therefore has a securely attached link between the hand element and the ‘high bar’, which is mounted on ball bearings and can rotate freely. Moreover, in the study, a mathematical model for the system is linearised, investigating the means of determining the state space in the system by applying Lagrange’s equation. The fuzzy logic linear quadratic regulator controller is used to identify how far the system responses stabilise when it is implemented. This paper investigates factors affecting the control of swing-up in the underactuated three-link Robogymnast. Moreover, a system simulation using MATLAB Simulink is conducted to show the impact of factors including overshoot, rising, and settling time. The principal objective of the study lies in investigating how a linear quadratic regulator or fuzzy logic controller with a linear quadratic regulator (FLQR) can be applied to the Robogymnast, and to assess system behaviour under five scenarios, namely the original value, this value plus or minus ±25%, and plus or minus ±50%. In order to further assess the performance of the controllers used, a comparison is made between the outcomes found here and findings in the recent literature with fuzzy linear quadratic regulator controllers.
Effects of Ski-Resort Activities and Transhumance Livestock Grazing on Rangeland Ecosystems of Mountain Zireia, Southern Greece
Authors: Kyriazopoulos Apostolos P. , Karatassiou Maria , Parissi Zoi M. , Abraham Eleni M. , Sklavou Paraskevi
Published: September 2022

The objective of the present study was to assess the impacts in time of the ski-resort infrastructure and transhumance livestock grazing on floristic composition, diversity, and rangeland health indices related to ecosystem stability and function. The study was carried out at a site under the pressure of ski resorts and livestock grazing (Ano Trikala) and a site only under the pressure of livestock grazing (Sarantapicho), both located at Mt Zireia, Southern Greece. The plant cover was measured at each site, and the floristic composition was calculated and classified into four functional groups: grasses, legumes, forbs, and woody species. Species richness, ecosystem function and stability landscape indices, diversity indices, and forage value were calculated. According to the results, the development of the ski resort in Ano Trikala had a neglectable negative impact on plant cover (reduced by 5%), while it had a minor impact on species richness and floristic diversity. Livestock grazing had a positive impact on maintaining plant cover in high values. These results suggest that livestock grazing can counterbalance the effects of ski resorts and related activities on plant cover and floristic diversity. Besides the relatively limited effects on the vegetation community, the ski resort significantly negatively impacted landscape composition, function, and stability. Forage value was 25% lower close to the ski resort, mainly due to the significantly lower percentage of legumes. Transhumance livestock grazing should be used as a management tool in ski-resort areas, as it benefits floristic diversity.
Optimization Methods as a Base for Decision Making in Land Consolidation Projects Ranking
Authors: Marinković Goran , Ilić Zoran , Trifković Milan , Tatalović Jelena , Božić Marko
Published: September 2022

Land consolidation (LC) is an activity that brings numerous benefits to rural areas. However, being resource demanding, the LC requires a decision on where it should be provided or where the limited resources should be distributed in order to maximize its effects. In order to avoid the subjective decision maker’s preferences, optimization methods for identifying the priorities are recommended. Bearing in mind that every optimization method could give different results, we proposed the utilization of multiple optimization methods for ranking the cadastral municipalities which are candidates for providing LC. In this research, the main aim was to find if it is possible to avoid the subjective decision making in cadastral municipalities (CM) as a candidate for LC ranking by utilizing the statistical approach. Additionally, in this research, the analysis was provided, varying the number of optimization criteria. In this research, two assumptions were adopted: (1) every single optimization method has the same weight, and (2) the differences between different ranks are results of random errors. After determining the average ranking of a certain cadastral municipality, its interval of ranking is calculated by using the Student’s distribution. Cadastral municipalities that belong within the interval of available resources are candidates for providing LC. In the case study, fifteen cadastral municipalities were researched, including eight and ten criteria for optimization, and results showed that there are significant differences between ranks of cadastral municipalities varying depending on the method utilized.
Measuring City-Level Transit Accessibility Based on the Weight of Residential Land Area: A Case of Nanning City, China
Authors: Le Jianming , Ye Kunhui
Published: September 2022

A large body of research on transit accessibility emphasizes the importance of methods to simulating the real-world travel process. Few efforts have been made to conduct empirical research and comparative analysis of overall city-level transit accessibility. In addition, most of literatures utilize census tracts combined with the buffer method to estimate transit travel demand or available service areas, failing to take into account the reality that different land-uses have their own population. This research aims to develop an overall index of city-level transit accessibility based on the weight of residential land area. We integrated five types of destinations and the coverage of residential area within the transit stop service area to evaluate the overall structural problems of land use and public transportation in the process of urban development. Based on a case study on Nanning City, it was found that the weighted average travel distance is increased by 5.42 km, but the overall weighted travel time of the city is shortened by 7.65 min. In addition, an increase in coverage within the stop threshold and a decrease in the number of residential communities outside the threshold indicate that transit accessibility facilitates urban expansion. The empirical results show that the overall transit accessibility index can provide a reasonable measure criterion for the compact spatial structure and support urban strategic planning and address the problem of land use and public transport in the process of urban development.
Land Certificated Program and Farmland “Stickiness” of Rural Labor: Based on the Perspective of Land Production Function
Authors: Sun Xiaoyu , Zhu Weijing , Chen Aili , Yang Gangqiao
Published: September 2022

The instability of farmland rights is the fundamental reason for the decrease in the “stickiness” of farmland in China. The Land Certificated Program (LCP) plays an important role in clarifying the ownership of land and stabilizing the property rights of land, as well as enhancing the land production function. Most existing literature focuses on the impact of the LCP on non-agricultural labor participation, while research on agricultural labor participation is scarce. This paper analyzes the impact of the LCP on farmland “stickiness” based on the perspective of land production function. This paper also applies propensity score matching (PSM) using CLDS data from 2016 and 2018 to evaluate the policy effect of the LCP on farmland “stickiness”, and conducts heterogeneity analysis and the robustness test. In addition, this paper examines the mechanism of the influence of LCP on farmland “stickiness” by using the mediating effect model. The results of this analysis showed that: (1) The impact of the LCP on farmland “stickiness” is significant, as the rate of agricultural labor participation has increased by 4.8% to 4.9%. (2) The incentive effect is heterogeneous, and has significant impacts on non-professional households, as well as on small and medium-sized of farms. (3) The sensitivity test revealed that unobservable factors do not have an impact on the LCP estimation results, and the results of the PSM estimation were robust. (4) The policy effect of the LCP at the village level also confirms the robustness of the promotion effect and the mechanism. (5) Land production function has a partial mediating effect on the impact of the LCP on farmland “stickiness”. Given these results, we must begin to consolidate, expand and make good use of the results of the LCP, support the connection between smallholders and modern agriculture, and enhance the land production function in order to stabilize agricultural production and realize agricultural modernization.
Reducing Nitrogen Fertilization in Olive Growing by the Use of Natural Chabazite-Zeolitite as Soil Improver
Authors: Medoro Valeria , Ferretti Giacomo , Galamini Giulio , Rotondi Annalisa , Morrone Lucia , Faccini Barbara , Coltorti Massimo
Published: September 2022

In order to improve the sustainability and productivity of modern agriculture, it is mandatory to enhance the efficiency of Nitrogen (N) fertilizers with low-impact and natural strategies, without impairing crop yield and plant health. To achieve these goals, the ZeOliva project conducted an experiment using a zeolite-rich tuff as a soil amendment to improve the efficiency of the N fertilizers and allow a reduction of their inputs. The results of three years of experimentation performed in three different fields in the Emilia-Romagna region (Italy) are presented. In each field, young olive trees grown on zeolite-amended soil (−50% of N-input) were compared to trees grown on unamended soil (100% N-input). Soils and leaves were collected three times every year in each area and analyzed to monitor the efficiency of the zeolite treatment compared to the control. Vegetative measurements were performed along with analysis of pH, Soil Organic Matter and soluble anions in soil samples, whereas total C and N, C discrimination factor and N isotopic signature were investigated for both soils and leaves. Besides some fluctuations of nitrogen species due to the sampling time (Pre-Fert, Post-Fertilization and Harvest), the Total Nitrogen of leaves did not highlight any difference between treatments, which suggest that plant N uptake was not affected by lower N input in the zeolite treatment. Results, including vegetative measurements, showed no significant differences between the two treatments in all the observed variables, although the control received twice the N-input from fertilization. Based on these results, it is proposed that zeolite minerals increased the N retention time in the soil, allowing a better exploitation by plants which led to the same N uptake of the control notwithstanding the reduction in the N inputs. The use of zeolite-rich tuff in olive growing thus allows a reduction in the amount of fertilizer by up to 50% and improves the N use efficiency with many environmental and economic benefits.
Comparative Residents’ Satisfaction Evaluation for Socially Sustainable Regeneration—The Case of Two High-Density Communities in Suzhou
Authors: Chen Jinliu , Pellegrini Paola , Wang Haoqi
Published: September 2022

With the 14th Five-Year Plan for Development, China is promoting people-oriented urban regeneration for residential communities built before 2000. Evaluations of quality of life (QoL) and considerations of social sustainability must play an important role in defining people-oriented regeneration projects. Residents’ satisfaction is an important indicator of QoL and is essential for achieving socially sustainable development. To contribute to the ongoing discussion about people-oriented urban regeneration, this paper studies the correlation between QoL and social sustainability, investigating residents’ perception in high-density communities through a satisfaction evaluation approach based on the QoL index. Two high-density communities in Suzhou were analyzed: Nanhuan, a high-rise, gated community in one of the first expansions of the city in the 80s; and Daoqian, a multi-story, non-gated community in the old town. Both communities have a typical urban morphology and were selected for their exemplary characteristics. The study used a mixed research method: field investigation, on-site interviews, and a survey with over 670 questionnaires conducted and analyzed. It also applied the Structural Equation Model (SEM) to explore and define the satisfaction evaluation factors. The two communities expressed concerns about different factors: in the case of the Nanhuan community, property management and spatial scenario creation were emphasized, whereas in the case of the Daoqian community, unrestricted space mobility, poor existing conditions, and the demand for various facilities and recreation spaces were most prominent. The research found that improving community environmental quality and facilities would, as one would expect, improve residents’ satisfaction in both communities. Still, our research also clearly indicated that diversified spatial activities, currently missing in both cases, and more opportunities for social interaction would enhance residents’ satisfaction. The findings of this study offer some insights regarding socially sustainable community regeneration, as well as decision-making processes and design strategies.
Soil Organic Carbon Storage in Urban Green Space and Its Influencing Factors: A Case Study of the 0–20 cm Soil Layer in Guangzhou City
Authors: Du Jifeng , Yu Mengxiao , Cong Yanguo , Lv Huanzhe , Yuan Zhongyou
Published: September 2022

Urban soils can contribute to organic carbon sequestration. The socioeconomic drivers of soil organic carbon (SOC) in urban areas may differ between regions due to the different land tenure and its derived green space management regimes. Currently, few studies focus on regions where public ownership of land was implemented. We examined the SOC storage and driving factors of urban green spaces in Guangzhou, China at 0–20 cm depth by variance and regression analysis. Our results showed that the total SOC storage did not vary significantly among green space types, with an average value of 2.59 ± 1.31 kg/m2. SOC increased with plot age (2–87 years) by 0.025 kg/m2/year (p = 0.026) and plot size (63–2058 m2) by 0.001 kg/m2/m2 (p = 0.026). Disturbance intensity was negatively correlated to SOC storage. Green space maintenance practices could promote SOC sequestration, but this benefit may be offset by high-intensity disturbances such as trampling, litter and debris removal and fragmentation of green spaces. To increase urban residential SOC storage, except for remediation of compacted soils, it is essential to promote house owners’ initiative in green space management and conservation by improving the current residential green space management regimes.
Influence of Urbanization on Spatio-Temporal Characteristics of Extreme Hourly Precipitation in Shenyang
Authors: Ao Xue , Zhai Qingfei , Zhao Chunyu , Cui Yan , Zhou Xiaoyu , Li Jingwei , Li Mingqian
Published: September 2022

Understanding changes in extreme hourly precipitation is critical to urban planners for building more sustainable and resilient cities. In this study, we use satellite nighttime light data, urban land area data, population, and economic data to objectively classify urban and rural stations. Based on the hourly precipitation data from national meteorological stations in 1974–2020 and from regional automatic weather stations in 2005–2020 in Shenyang (China), the spatio-temporal distribution characteristics of the thresholds, maximums, intensities, and frequencies of extreme hourly precipitation (ExHP) in urban and rural areas are analyzed and compared. The results show that the large-value centers of ExHP thresholds, maximums, and intensities are mainly concentrated in urban areas. Both the frequency and intensity of ExHP at urban stations are obviously larger than those at rural stations, and the peaks mainly appear at night for stations of both two types. From 1974 to 2020, the average frequency and intensity of ExHP at urban stations both show increasing trends, with the increasing rate being much higher than those at rural stations. In terms of temporal variation, precipitation events of the abrupt type are the most frequent, accounting for 48.6% of the total, followed by the growing type (42.7%) and continuous type (8.7%). ExHP events of the abrupt type are mostly concentrated in Kangping County and Faku County of Northern Shenyang, but rarely occur in Xinmin City. ExHP events of the growing type are mainly found in Xinmin City and the municipal district of Shenyang. For urban stations, the ExHP frequency decreases in the early stage of urbanization, while increasing evidently during the rapid urbanization stage. However, the situation is just the opposite for rural stations. This indicates that the rapid urbanization in Shenyang has a certain impact on the increase in ExHP.
Impact of Long-Term Conservation Agriculture Practices on Phosphorus Dynamics under Maize-Based Cropping Systems in a Sub-Tropical Soil
Authors: Anil Ajin S. , Sharma Vinod K. , Jiménez-Ballesta Raimundo , Parihar Chittar M. , Datta Siba P. , Barman Mandira , Chobhe Kapil A. , Kumawat Chiranjeev , Patra Abhik , Jatav Surendra Singh
Published: September 2022

Over the past decade, scientific studies have increasingly concentrated on the effects of global phosphorus (P) scarcity on food security. A comprehensive strategy that considers demand reduction and recycling possibilities is needed to address the global P scarcity. Reduced tillage along with crop residue retention could decrease fixation of P in soil, improve labile P content and enhance organic-P (Po) buildup and its mineralization by phosphatases; this could be an extra benefit of conservation agriculture (CA) in soils. To study the impact of long-term CA on soil organic and inorganic P fractions and their distribution, a long-term field trial was conducted under a maize-based cropping system with different tillage (zero tillage (ZT), permanent bed (PB) and conventional till (CT) and cropping system (maize–wheat–mungbean (MWMb), maize–chickpea–sesbania (MCS), maize–mustard–mungbean (MMuMb) and maize–maize–sesbania (MMS)). Phosphorus dynamics were studied through sequential fractionation (organic and inorganic P) at 0–5 and 5–15 cm soil depth. The findings showed that a higher amount of soluble and loosely bound P (SL-P) was detected in ZT among the inorganic P fractions, whereas iron-bound P (Fe-P), aluminum-bound P (Al-P), reductant soluble P (RES-P) and calcium-bound P (Ca-P) were found higher in CT in both soil depths. Among Organic-P fractions, moderately labile and non-labile Po was found higher in PB and ZT but, in the case of labile Po, it was found insignificant with respect to tillage operations. Significant synergistic effects of winter legume (chickpea) with summer legumes (sesbania and mungbean) in crop rotation were observed on SL-P, Labile Po, Humic acid-Po, Alkaline phosphatase and MBP at 0–5 and 5–15 cm soil depths. Given the potential relevance of understanding P dynamics for efficient P management in long-term conservation agriculture practices, our findings offers critical new insight for the P management for sustainable development.
Walking in China’s Historical and Cultural Streets: The Factors Affecting Pedestrian Walking Behavior and Walking Experience
Authors: Tian Mimi , Li Zhixing , Xia Qinan , Peng Yu , Cao Tianlong , Du Tianmei , Xing Zeyu
Published: September 2022

The urban street has evolved into an important indicator reflecting citizens’ living standard today, and pedestrian walking activity in the streets has been proved to be a major facilitator of public health. Uncertainties, however, exist in the factors affecting pedestrian walking behavior and walking experience in streets. Especially, the factors affecting pedestrian walking behavior and walking experience in the historical and cultural streets. For the study of their main influencing factors, Hefang Street business block and Gongchen Bridge life block in Hangzhou are selected here as the study objects. Both non-participatory and participatory research methods are adopted to collect pedestrian information and observe pedestrians’ ambiguous behavior, specific behavior, and stopping behavior. According to the study result, walking preference, walking time, environmental characteristics, and land-use mix (LUM) significantly impact pedestrian walking motivation. The type differences between Gongchen Bridge life block and Hefang Street business block leads to the difference in pedestrians’ behaviors and their stopping time in business. Meanwhile, gender differences bring pedestrians’ significant differences in walking motivation. Pedestrian walking preference and walking time are positively correlated with walking motivation in both streets. Environmental characteristics and LUM have also been proved to be important influencing factors of pedestrians’ walking motivation. In this article, design and planning strategies are proposed for streets of different types in an attempt to provide reference for the revitalization and utilization of cultural heritage streets.
Small Cultural Forests: Landscape Role and Ecosystem Services in a Japanese Cultural Landscape
Authors: Piras Francesco , Fiore Beatrice , Santoro Antonio
Published: September 2022

Small woods, linear tree formations, or scattered trees in agricultural areas are receiving increasing attention for their multifunctional role, especially if associated to cultural landscapes. Osaki Kodo’s Traditional Water Management System for Sustainable Paddy Agriculture represents one of the most important cultural landscapes (satoyama) of Japan, also included by the FAO in the GIAHS (Globally Important Agricultural Heritage Systems) Programme. Here, local farmers surrounded their farmhouses with small woods, called igune, as a protection from the cold winter wind, creating a peculiar landscape characterized by an intensively cultivated plain dotted with small wood patches. The research aims at deepening the knowledge of igune, evaluating the landscape role and monitoring their changes in the last 20 years, through multitemporal and spatial analyses. In addition, a literature review has been performed to assess other Ecosystem Services (ESs) provided by igune within the study area. Despite the limited overall surface, 1737 igune and small woods currently characterize the area, with 72% of them having a surface smaller than 0.5 hectares. The multitemporal and spatial analyses show that their number, distribution, and spatial pattern remained almost completely unchanged in the last 20 years, testifying their key role in characterizing the local cultural landscape. Least-Cost Path analysis highlighted a crucial role in connecting the two forest nodes of the region, as 90% of the path passes inside more than 70 different igune and small woods. Literature review demonstrated that igune and other small woods still provide various ESs, including ecological network, habitat for various flora and fauna species, firewood, and byproducts, as well as cultural services. This maintenance of the traditional management in cultural forests is crucial not only to retain their landscape role, but mostly for the preservation of the related ESs, as changes in the management can lead to changes in horizontal and vertical structures, and in species composition.
Identifying Key Areas of Green Space for Ecological Restoration Based on Ecological Security Patterns in Fujian Province, China
Authors: Wang Zhenfeng , Liu Yan , Xie Xiangqun , Wang Xinke , Lin Hong , Xie Huili , Liu Xingzhao
Published: September 2022

Urban expansion has resulted in the fragmentation of green spaces. Based on the concept of a living community that integrates mountains, rivers, forests, farmlands, lakes, and grasslands, the extraction of key elements in green spaces of regional ecosystems provides core scientific support for the ecological restoration of territorial spaces. According to the ecological service function importance and ecological sensitivity, the ecological sources were identified in this study. Furthermore, we distinguished the ecological corridors using the minimum cumulative resistance (MCR) model and identified the key areas of green spaces using the circuit theory model. The result showed that (1) 62 ecological sources were present with a total area of 4696 km2, of which green space accounted for 98.19%; meanwhile, 151 ecological corridors (optimal path) were densely distributed in the southwest region around the Daimao and Bopingling mountains. (2) The key areas of ecological restoration in the study area included 17 key ecological sources and 19 key ecological corridors. The area covered by ecological pinch points was 1327 km2, among which 77.54% of green space comprised forest area. The area of ecological barriers was 9647 km2, and the forest area still accounted for the highest proportion (63.92%). (3) Based on a comprehensive analysis of the spatial distribution of key areas of ecological restoration and green spaces, we formulated classified ecological restoration measures. The study findings are expected to provide a reference for planning the ecological restoration of territorial spaces.
Staging St George after the Reformation
Authors: Hopkins Lisa
Published: September 2022

This essay considers various ways in which St George, an important figure in mummers’ plays before the Protestant Reformation, remained a presence in drama and popular entertainment long after one would have expected him to have disappeared. It notes his importance in the agricultural calendar, his strong association with fireworks, his popular designation as a specifically English saint, and some of the customs traditionally observed on his feast day of 23 April. It then moves on to consider some of the plays in which he is mentioned or alluded to, including works by Shakespeare, Christopher Marlowe, Francis Beaumont, and John Fletcher, as well as a romance by Richard Johnson that was later dramatized, and culminates with references in three plays produced by members of the Cavendish family of Bolsover and Welbeck. It argues that referring to St George offered a way of talking about Englishness even when (perhaps especially when) that concept was contested, and also suggests that the legendary folk hero Guy of Warwick, presented in some texts as the son of St George, could sometimes act as a dramatic proxy for the saint.
Graphene-Family Lubricant Additives: Recent Developments and Future Perspectives
Authors: Liu Yanfei , Yu Shengtao , Shi Qiuyu , Ge Xiangyu , Wang Wenzhong
Published: September 2022

Graphene-family materials have been investigated by researchers as promising additives for various lubrication systems due to their unique physical-chemical properties. It has been proven that graphene-family materials can lead to enhanced lubrication and wear-resistance performance, which have potential to reduce the energy losses and carbon emissions, and the wear of machines for industrial applications. Experimental, theoretical, and simulation studies have been performed to investigate the tribological behaviors of graphene-family materials as additives. The tribological properties of graphene-family materials, including graphene, reduced graphene oxide, functionalized graphene, and the combination of graphene-family materials and other materials as additives, and the fundamental mechanism are systematically reviewed and concluded. The authors also discuss the potential engineering applications of graphene-family materials as lubricating additives, and the unsolved issues and optimistic outlooks in the near future.
Effect of ECAP Route Type on the Microstructural Evolution, Crystallographic Texture, Electrochemical Behavior and Mechanical Properties of ZK30 Biodegradable Magnesium Alloy
Authors: Alateyah Abdulrahman I. , Alawad Majed O. , Aljohani Talal A. , El-Garaihy Waleed H.
Published: September 2022

In this study, billets of the ZK30 (Mg-3Zn-0.6 Zr-0.4 Mn, wt%) alloy were Equal Channel Angle Pressing (ECAP) processed for up to four passes of routes Bc (with rotating the sample 90° in the same direction between the subsequent passes), A (without sample rotation), and C (with sample rotating 180°) after each pass at a temperature of 250 °C and a ram speed of 10 mm/min using a die with an internal channel angle of 90°. The microstructural evolution and the crystallographic texture were investigated using a Scanning Electron Microscope (SEM) equipped with the Electron Back-Scatter Diffraction (EBSD) technique. Corrosion measurements were conducted in ringer lactate which is a simulated body fluid. The Vickers microhardness test and tensile tests were conducted for the alloy before and after processing. The as-annealed billets exhibited a bimodal structure as fine grains (more than 3.39 µm) coexisted with almost-equiaxed coarse grains (less than 76.73 µm); the average grain size was 26.69 µm. Further processing until four passes resulted in enhanced grain refinement and full Dynamic Recrystallization (DRX). ECAP processing through 4-Bc, 4-A, and 4-C exhibited significant reductions in grain size until they reached 1.94 µm, 2.89 µm, and 2.25 µm, respectively. Four-pass processing also resulted in the transformation of low-angle grain boundaries into high-angle grain boundaries. The previous conclusion was drawn from observing the simultaneous decrease in the fraction of low-angle grain boundaries and an increase in the fraction of high-angle grain boundaries. The pole figures revealed that 4-Bc, 4-A, and 4-C reduced the maximum texture intensity of the as-annealed billets. The potentiodynamic polarization findings revealed that route Bc is the most effective route in improving the corrosion rate, whereas the Electrochemical Impedance Spectroscopy (EIS) revealed that routes A and Bc improved the corrosion resistance with nearly identical values. Finally, 4-Bc resulted in the highest increase in Vickers hardness, yield stress, and ultimate tensile strength with values of 80.8%, 19.3%, and 44.5%, alongside a 31% improvement in ductility, all compared to the AA condition.
Effect of Post-Heat Treatment Temperature on Interfacial Mechanical Properties of Cold-Rolled Ti/Al Clad Material
Authors: Yoo Sang-Kyu , Kim Ji-Won , Oh Myung-Hoon , Choi In-Chul
Published: September 2022

Titanium and titanium alloys possess low density, high specific strength, and excellent corrosion resistance, but are expensive and have low formability at room temperature. Therefore, to reduce cost and achieve excellent properties, titanium and titanium alloys are jointed with aluminum and its alloys, which are inexpensive and have low density and excellent room temperature formability. Cladding is a widely used solid-state bonding technique, and the post-heat treatment of titanium/aluminum clad materials is required to improve their interfacial properties, which is important to ensure the reliability of Ti/Al-clad materials. The interfacial properties of Ti/Al-clad materials are significantly affected by changes in the microstructure and mechanical properties after the post-heat treatment. Thus, in this study, the relationship between the microstructure and mechanical properties at the interface of Ti/Al-clad materials was analyzed after the post-heat treatment at several different temperatures. The thick diffusion and intermetallic compound layer was formed with post-heat treatment owing to the active diffusion of Al atoms. As a result, their uniaxial and nanomechanical properties were varied with the interfacial characteristics of the Ti/Al-clad material.
Special Issue “Corrosion Resistance of Alloy and Coating Materials”
Authors: Brytan Zbigniew
Published: September 2022

This Special Issue aims to include the latest research findings on the corrosion phenomena that occur in various materials, both solid and coating materials [...]
Water Desalination Using the Once-through Multi-Stage Flash Concept: Design and Modeling
Authors: Thabit Qahtan , Nassour Abdallah , Nelles Michael
Published: September 2022

Thermal water desalination is one of the most important techniques to solve the water scarcity problem in many regions of the world. Out of around 7.8 billion people in the world, only about 6 billion of them have access to clean water; notably, climate change plays a major role in accelerating the evaporation rate of water from water bodies, which in turn increases the scarcity. Multi-stage flash, recognized to have a high rate of water production in comparison with other available technologies, accounts for 35% of water desalination facilities worldwide. This paper presents a detailed Excel model to evaluate the amount of energy required to drive 16 stages of multi-stage flash. This model aims to design and evaluate the amount of thermal energy required for such projects and optimize their performance by calibrating the governing parameters. Furthermore, the 16 stages were simulated via the Ebsilon 13.02 software package to match the results and evaluate the fulfillment of the plant requirements. The temperature drop of the brine stream was 2.34 °C/stage. The top brine temperature was 130 °C. The results show that 29.5 kg/s of superheated steam is required to desalinate 162 kg/s of 2500 kg/s influent mass flow of brine. The effect of water intake temperature was also examined by using Ebsilon. The performance ratio decreased from 5.49 to 2.66 when the water intake temperature decreased from 30 °C to 5 °C.
Electrical and Magnetic Transport Properties of Co2VGa Half-Metallic Heusler Alloy
Authors: Yu Litao , Li Zhe , Zhu Jiajun , Liu Hongwei , Zhang Yuanlei , Cao Yiming , Xu Kun , Liu Yongsheng
Published: September 2022

This study performed a systematic experimental investigation into the structural, magnetic, and transport properties of the Co2VGa Heusler alloy, which was theoretically predicted to exhibit half-metallic ferromagnetism. It has been experimentally found that the studied alloy has a relatively high-ordered L21 cubic structure at room temperature and orders ferromagnetically below ~350 K. Interestingly, by fitting the electric transport data with the properly governing equations in two different temperature regions, the two-magnon scattering process (the T9/2 dependence) appears in the temperature range from 30 to 75 K. Moreover, the magnetoresistance effect changes from a negative value to a positive value when the temperature is below 100 K. Such experimental findings provide indirect evidence that the half-metallic nature of this alloy is retained only when the temperature is below 100 K. On the other hand, the magnetic transport measurements indicate that the anomalous Hall coefficient of this alloy increases when the temperature increases and reaches a relatively high value (~8.3 μΩ·cm/T) at 300 K due to its lower saturated magnetization. By analyzing the anomalous Hall resistivity scale with the longitudinal resistivity, it was also found that the anomalous Hall effect can be ascribed to the combined effect of extrinsic skew scattering and intrinsic Berry curvature, but the latter contribution plays a dominant role.
On-Line Core Losses Determination in ACSR Conductors for DLR Applications
Authors: Riba Jordi-Roger , Liu Yuming , Moreno-Eguilaz Manuel , Sanllehí Josep
Published: September 2022

Dynamic line rating (DLR) is a method that focuses on dynamically determining the maximum allowable current of power lines, while ensuring they operate within safe limits. DLR needs to monitor the temperature and current of the line in real-time, as well as the weather variables in the surroundings of the power line. DLR approaches also require determining the AC resistance of the power line conductors, which is a key parameter that enables it to determine Joule and core losses. This paper presents an approach for an on-line alternating current (AC) resistance estimation of aluminum conductor steel-reinforced (ACSR) conductors to determine the DLR capability of such conductors from real-time conductor and meteorological parameter measurements. For this purpose, conductors with one, two and three layers of aluminum strands are analyzed in detail. Based on the experimental results presented in this paper, two possible approaches are proposed.
Comprehensive Evaluation of the Sustainability of Waste Concrete towards Structural Concrete Application in Freeze-Thaw Environment
Authors: Wei Da , Zhu Pinghua , Gao Shan , Yan Xiancui , Liu Hui , Fan Haifeng
Published: September 2022

To promote the in-situ and structural application of waste concrete in cold regions, the sustainable application potential of waste concrete in a freeze-thaw (F-T) environment was comprehensively evaluated from three aspects of performance, environmental load, and economic benefit. The recycled aggregate concrete (RAC) was produced by recycled coarse aggregate (RCA), which was obtained from the crushing of natural aggregate concrete (NAC) after every F-T 150 cycles until F-T failure. The effects of F-T damage of parent concrete on the physical properties of RCA and mechanical and frost resistance of RAC under 35% flexural stress were studied. Besides, the sustainability of NAC and RAC was compared and analyzed by emergy theory. The results suggested that the physical properties of RCA deteriorated gradually with the accumulation of F-T damage to parent concrete. The RCA obtained from parent concrete that suffered F-T damage could be used as coarse aggregate for structural concrete when F-T damage is smaller than 0.367. The F-T damage of parent concrete had an adverse effect on the mechanical properties and frost resistance of RAC. The frost resistance of RAC obtained from parent concrete with larger F-T damage was worse. The RAC prepared from parent concrete without F-T failure can serve 50 years in cold regions, while that with F-T failure can only serve 30 years. The F-T damage microelements were dispersed in the adhesive mortar of RCA and transferred to RAC, resulting in the reduction of the mechanical properties and frost resistance of RAC. Emergy analysis showed that the reuse of waste concrete after F-T failure required higher economic input, higher environment load, lower output efficiency, and sustainability. The performance, environmental load and economic benefit of RAC prepared by using waste concrete after F-T failure were inferior to that of waste concrete without F-T failure. Waste concrete after F-T failure is not recommended to be used as coarse aggregate for structural concrete.
Dynamic Compressive Mechanical Properties of UR50 Ultra-Early-Strength Cement-Based Concrete Material under High Strain Rate on SHPB Test
Authors: Wang Wei , Zhang Zhonghao , Huo Qing , Song Xiaodong , Yang Jianchao , Wang Xiaofeng , Wang Jianhui , Wang Xing
Published: September 2022

UR50 ultra-early-strength cement-based self-compacting high-strength material is a special cement-based material. Compared with traditional high-strength concrete, its ultra-high strength, ultra-high toughness, ultra-impact resistance, and ultra-high durability have received great attention in the field of protection engineering, but the dynamic mechanical properties of impact compression at high strain rates are not well known, and the dynamic compressive properties of materials are the basis for related numerical simulation studies. In order to study its dynamic compressive mechanical properties, three sets of specimens with a size of Φ100 × 50 mm were designed and produced, and a large-diameter split Hopkinson pressure bar (SHPB) with a diameter of 100 mm was used to carry out impact tests at different speeds. The specimens were mainly brittle failures. With the increase in impact speed, the failure mode of the specimens gradually transits from larger fragments to small fragments and a large amount of powder. The experimental results show that the ultra-early-strength cement-based material has a greater impact compression brittleness, and overall rupture occurs at low strain rates. Its dynamic compressive strength increases with the increase of strain rates and has an obvious strain rate strengthening effect. According to the test results, the relationship curve between the dynamic enhancement factor and the strain rate is fitted. As the impact speed increases, the peak stress rises, the energy absorption density increases, and its growth rate accelerates. Afterward, based on the stress–strain curve, the damage variables under different strain rates were fitted, and the results show that the increase of strain rate has a hindering effect on the increase of damage variables and the increase rate.
Quantum Cutting in Ultraviolet B-Excited KY(CO3)2:Tb3+ Phosphors
Authors: Li Dechuan , Zhu Guangping
Published: September 2022

Highly efficient quantum cutting KY(CO3)2:Tb3+ phosphors excited by ultraviolet B (UVB) and ultraviolet C (UVC) were investigated. The structural and spectroscopic properties were characterized by XRD analysis and fluorescence spectrophotometry, respectively. The results showed that the monoclinic crystal structure of KY(CO3)2:Tb3+ remained in the Tb3+ doping range of 0~100%. In the excitation spectrum, two intense excitation peaks were observed in the ultraviolet range. Under the excitation of 283 nm, the maximum quantum efficiency of KY(CO3)2:0.7Tb3+ could reach 119%. However, the most efficient quantum cutting occurred at the 5K8 excited state in the cross-relaxation of 5K8 + 7F65D4 + 5D4. The Tb3+ content could be selected arbitrarily in the KY(CO3)2 host without any concentration quenching. Optimal quantum cutting concentrations of Tb3+ in KY(CO3)2 were 0.7 and 0.3 for the excitation of UVB and UVC, respectively. UVB-excited phosphors are more popular with high transparency in products such as glass or resin. A quick response code was fabricated by resin to show the hidden information clearly. Therefore, the highly efficient phosphor could be a candidate material for the application in information identification technology.
Growth Mechanism of Semipolar AlN Layers by HVPE on Hybrid SiC/Si(110) Substrates
Authors: Koryakin Alexander A. , Kukushkin Sergey A. , Osipov Andrey V. , Sharofidinov Shukrillo Sh. , Shcheglov Mikhail P.
Published: September 2022

In this work, the growth mechanism of aluminum nitride (AlN) epitaxial films by hydride vapor phase epitaxy (HVPE) on silicon carbide (SiC) epitaxial layers grown on silicon (110) substrates is investigated. The peculiarity of this study is that the SiC layers used for the growth of AlN films are synthesized by the method of coordinated substitution of atoms. In this growth method, a part of the silicon atoms in the silicon substrate is replaced with carbon atoms. As a result of atom substitution, the initially smooth Si(110) surface transforms into a SiC surface covered with octahedron-shaped structures having the SiC(111) and SiC(111¯) facets. The SiC(111)/(111¯) facets forming the angle of 35.3° with the original Si(110) surface act as “substrates” for further growth of semipolar AlN. The structure and morphology of AlN films are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), reflection high-energy electron diffraction (RHEED) and Raman spectroscopy. It is found that the AlN layers are formed by merged hexagonal microcrystals growing in two directions, and the following relation is approximately satisfied for both crystal orientations: AlN(101¯3)||Si(110). The full-width at half-maximum (FWHM) of the X-ray rocking curve for the AlN(101¯3) diffraction peak averaged over the sample area is about 20 arcmin. A theoretical model explaining the presence of two orientations of AlN films on hybrid SiC/Si(110) substrates is proposed, and a method for controlling their orientation is presented.
Wear Mechanisms and Performance of PET Shredder Blade with Various Geometries and Orientations
Authors: Wong Jin Hoong , Karen Wong Min Jin , Bahrin Saffuan Awg , Chua Bih Lii , Melvin Gan Jet Hong , Siambun Nancy Julius
Published: September 2022

Shredder blade is the main component of a shredder machine used in plastic recycling. A comparative performance study was conducted on the shredder blade with different geometries and orientations to understand its wear and shredding mechanism. Identification of the loading distribution along the shredder blades was observed in different orientations. The microstructure and hardness of the worn cutting edge and as-received shredder blade were characterised by optical microscopy, scanning electron microscopy along with the energy dispersive X-ray, X-ray diffraction analysis and hardness testing. The wear mechanism in the shredder blades was categorised as progressive wear. The progressive wear was due to the abrasive, adhesive, and oxidation wear. Recycling efficiency, shredding efficiency, and percentage retention are the parameters used to evaluate the performance of the machine with various geometries and orientations. The best combination of the geometry and orientation is the double-edge shredder blade with spiral orientation, which exhibited recycling efficiency at 97.39 ± 0.04%, shredding efficiency at 69.53 ± 1.32%, and retention at 2.61 ± 0.04%, along with a smaller number of blades recorded severe wear.
Simulation Analysis on Electromagnetic Vibration and Noise of Novel Mechatronic-Electro-Hydraulic Coupler
Authors: Liu Baoquan , Zhang Tiezhu , Zhang Hongxin , Zhang Zhen , Cao Yang
Published: September 2022

The mechatronic-electro-hydraulic coupler (MEHC) is a novel type of multisource coupling power device which integrates a traditional permanent magnet synchronous motor with a swash plate axial piston pump/motor to realize the mutual conversion of electrical energy, mechanical energy, and hydraulic energy. In order to improve the MEHC’s noise, vibration, and harshness performance, an electromagnetic vibration and noise simulation analysis was performed with a six-pole 36-slot motor as the research object. Firstly, the spatial order and frequency of the radial electromagnetic force were deduced by an analytical method. Subsequently, the electromagnetic field was simulated, and the electromagnetic force was extracted via a fast Fourier transform using Ansys/Maxwell software for the numerical verification. Thereafter, the harmonic response module coupled the electromagnetic field with the structural field for the harmonic response analysis. Ultimately, the research results were imported into the harmonic acoustics module for a noise simulation analysis and two different-shape magnetic isolation bridges optimization schemes were proposed. The results suggested that both optimisation solutions could effectively reduce motor vibration and noise. Scheme one reduced the maximum noise by about 6.5% and scheme two by 10.4%. The analysis process and conclusion provide a theoretical basis for the vibration and noise analysis of permanent magnet synchronous motors with different integer slots.