bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecularly Imprinted Polymer-Based Optical Sensor for Isopropanol Vapor
Authors: Pathak A. K. , Limprapassorn P. , Kongruttanachok N. , Viphavakit C.
Published: August 2022

Recent advances have allowed the monitoring of several volatile organic compounds (VOCs) in human exhaled breath, and many of them are being utilized as a biomarker to diagnose several diseases, including diabetes. Among several VOCs, isopropanol (IPA) has been reported as a common volatile compound in the exhaled breath of patients with type 1 and type 2 diabetes. In this article, an experimental approach is discussed to develop a highly selective and sensitive IPA vapor sensor system. The fabricated sensor is comprised of a small and portable glass slide coated with molecularly imprinted polymer containing specific binding sites compatible with IPA molecules. The developed sensor is based on the wavelength interrogation technique. The fabricated device is analyzed for the detection of IPA vapor with different concentrations varying from 50% to 100%. The sensor exhibits maximum sensitivities of 0.37, 0.30, and 0.62 nm/%IPA, respectively, for 30, 60, and 90 min, respectively, and an excellent sensitivity of 0.63 nm/%IPA for 120 min exposure along with good selectivity among a similar class of VOCs. The major features of the sensor i.e., small size, portability, cost-effectiveness, high sensitivity, and good selectivity, make it a potential candidate for diabetes monitoring. The promising results of the sensor illustrate its potential in diabetes monitoring applications.
Analysis of Landscape Pattern Evolution and Driving Forces Based on Land-Use Changes: A Case Study of Yilong Lake Watershed on Yunnan-Guizhou Plateau
Authors: Ma Guoqiang , Li Qiujie , Yang Shuyu , Zhang Rong , Zhang Lixun , Xiao Jianping , Sun Guojun
Published: August 2022

In order to explore the landscape pattern evolution and driving forces of the Yilong Lake watershed, the combined method of supervised classification with manual visual interpretation based on the landsat5TM/8OLI remote sensing image data sources was used to establish a high-precision spatial distribution information database of the Yilong Lake watershed. Landscape index was used to analyze the distribution and spatial pattern change characteristics of various land-use types. Based on correlation and principal component analysis, we discuss the relationship between the change characteristics of land-use type, distribution and spatial pattern, and the interference of local socio-economic development and natural factors. The results show that: (1) In the past 30 years, the land-use types of the Yilong Lake watershed are mainly forest, garden plot and cultivated land. The forest area decreased significantly by 30.45 km2, of which the fastest reduction stage was from 2000 to 2005, with a total reduction of 20.56 km2. The garden plot conversion is relatively large, with a total of 181.69 km2 transferred out, of which 28.84 km2 has become unused land, respectively. (2) In the past 30 years, the maximum patch index decreased by 9.94% and the patch density index increased by 14.25%, indicating that the landscape fragmentation in the whole basin increased. The Shannon diversity index showed an increasing process; the aggregation index showed a decreasing process. (3) The change in landscape pattern in the watershedwas closely related to economic growth, population growth, social affluence and agricultural development. Natural factors, social factors and economic indicators are significantly positively correlated with patch density, edge density, landscape shape index and Shannon diversity index, and significantly negatively correlated with the largest patch index and the contagion index. On the whole, the wetlands in the basin are shrinking and the landscape diversity is changing. Reducing the excessive impact of human activities on the watershed ecosystem is a key factor for the local protection of wetland resources and the maintenance of wetland ecological functions.
An Analysis on the Determining Factors of Farmers’ Land-Scale Management: Empirical Analysis Based on the Micro-Perspective of Farmers in China
Authors: Li Xiang , Lee Hyukku
Published: August 2022

In the context of continuous improvement in China’s land system, the development of the rural economy is insufficient, and the growth of farmers’ income lacks sustainable momentum. The development of the internet and agricultural socialization services has had a huge impact on farmers’ land-scale management. In particular, the proliferation of internet technology in rural areas could affect farmers’ use of agricultural socialization services and increase farmers’ willingness to operate their land on a large scale. However, there is a lack of empirical evidence on the impact of the internet and agricultural socialization services on farmers’ land-scale management decisions. This study constructs a probit model using the cross-sectional data of the nationally representative CFPS2018, and empirically tests the influencing factors of farmers’ land-scale management decisions and the mechanism of heterogeneity. The research results show that, first, the popularity of the internet significantly promoted farmers’ decisions towards land rented-out, but has no significant impact on land rented-in; second, agricultural socialization services are significantly negatively correlated with farmers’ decisions towards land rented-out, but the internet may moderate this inhibitory effect and has an incentive effect on farmers’ land rented-in; third, the results of heterogeneity analysis show that the impact of the internet and agricultural socialization services on farmers’ land-scale management decisions vary with income levels and regions. Therefore, the policy direction should focus on making “internet + agriculture” and agricultural socialization services benefit all farmers, to more effectively improve the efficiency of rural land use and promote the optimal allocation of rural resources.
Spatial Planning Implementation Effectiveness: Review and Research Prospects
Authors: Li Guan , Wang Liping , Wu Cifang , Xu Zhongguo , Zhuo Yuefei , Shen Xiaoqiang
Published: August 2022

The question of how to implement spatial planning more effective is a fundamental but very difficult one and one that has been of great interest to both the academic and practical community. However, a comprehensive review of the conceptual models and methodological systems for evaluating spatial planning implementation, and the existing practical research results of various types of spatial planning implementation evaluation, are yet to be presented. The study systematically reviews the main research findings in the field of spatial planning implementation from four aspects: conceptual analysis, measurement methods, evaluation frameworks and evaluation methods. This study found three distinct evolutionary features of research in this field: (1) The evaluation concept changes from complete rationality to limited rationality; (2) research methodology changes from a simple closed system to a complex open system; (3) the research perspective shifts from the map to the main body of planning implementation behavior. It is suggested that an important part of future research lies in establishing a system for evaluating the effectiveness based on a single subject who is an actor in the planning implementation process. On this basis, the micro-influencing mechanisms of planning implementation effects will then be explored. Deepening the research to the individual level will help improve planning implementation’s effectiveness.
Popularizing Structural Geology: Exemplary Structural Geosites from the Apuan Alps UNESCO Global Geopark (Northern Apennines, Italy)
Authors: Frassi Chiara , Amorfini Alessia , Bartelletti Antonio , Ottria Giuseppe
Published: August 2022

Popularizing endogenic geological processes that act deep on the Earth during geologic time producing orogenic belts requires a great effort. Consequently, geosites dealing with structural geology are surveyed with a lower frequency. Geological structures, however, may strongly control and model the territory and/or trigger the exogenous processes responsible for a specific landform/landscape. We describe here three geosites in the Apuan Alps UNESCO Global Geopark (Tuscany, Italy) to highlight their geoheritage values. We used the classical methods applied in structural geology to conceive and design three new interpretative panels of structural geosites using simple language and graphic schemes that facilitate the understanding of geological structures. The three selected structures were produced by different deformation regimes and at different structural depths. The first geosite is the boundary between the metamorphic and non-metamorphic rocks and represents the boundary of the Apuan Alps tectonic window. The second geosite is the spectacular Mt. Forato natural arch and the third represents a beautiful example of folds. Each panel is characterized by QR codes that allow the reader to access a short geological glossary, the Apuan Alps Geopark website, and a short evaluation survey on the quality of the interpretative panel.
Protecting Traditional Agricultural Landscapes by Promoting Industrial Integration Development: Practices from Important Agricultural Heritage Systems (IAHS) Sites in China
Authors: Zhang Yongxun , Li Xiande
Published: August 2022

Traditional agricultural landscapes (TAL) have a long history. They have received significant attention due to concerns regarding their multiple functions and scarcity. Important Agricultural Heritage Systems (IAHS), designated by the FAO or some countries, are typical TAL that are facing conservation problems. This study takes IAHS as an example and examines the pathway and coordinating mechanism that industrial integration development (IID) uses to promote TAL conservation using available literature reviews and field surveys in IAHS sites. The findings suggest that the main pathways protecting IAHS, depending on IID, include increasing product price by IAHS branding, diversifying farmers’ income by developing special resources, and employing more seasonal surplus laborers by extending local industrial chains. Building a fair and reasonable benefit coordination mechanism among stakeholders in IID is crucial to prompt IAHS conservation. It rests on accurately identifying key stakeholders in IAHS conservation, selecting industrial organization modes that are suitable to an IAHS site, and introducing beneficial distribution mechanisms that can encourage farmers to stay on the farm. The case studies show that diversifying income channels and increasing income with industrial development are the main forces driving farmers to protect IAHS. The IID based on IAHS resources and the win-win benefit distribution principle are key to sustainable conservation.
Experimental Investigation of Triboelectrification Behaviour in the Friction Process
Authors: Li Guobin , Yang Sifan , Xing Pengfei , Liu Ting , Gao Honglin , Song Yuchao , Zhang Hongpeng
Published: August 2022

The triboelectrification phenomenon can occur during the friction process of metal contact pairs. An in-depth understanding of triboelectrification behaviour is incredibly beneficial to controlling friction and wear. However, due to the complexity of the driving mechanism, it is still challenging to gain a thorough understanding of the triboelectrification behaviour of metal–metal contact pairs. To further reveal the triboelectrification behaviour during the friction process of metal pairs, wear experiments of GCr15 steel–cast iron were carried out on a CFT-I tribometer under oil-free and oil lubrication conditions. The triboelectric current signal was collected during the investigation, and its variation was discussed. The result shows that the varying trend of the triboelectric current was consistent with that of the friction coefficient in the friction process. The triboelectrification of similar metal contact pairs primarily driven by material transfer was closely related to friction and wear conditions.
Wear Properties of C-MoS2-PTFE Composite Coating Prepared on 4032 Aluminum Alloy
Authors: Chen Xuehui , Zhang Yuxi , Li Congmin , Huang Lei , Wang Yu , Gao Ting , Zhang Zhenbin , Liu Wei
Published: August 2022

A large number of joint friction pairs work during the work of scroll compressors, resulting in high energy consumption and short service life of scroll compressors. To improve the tribological performance of friction pairs of the scroll compressors, the C-MoS2-PTFE (Polytetrafluoroethylene) lubrication coating is prepared through spraying technology on the surface of 4032 aluminum alloy, a common material for scroll compressors. The microstructure of the C-MoS2-PTFE coating was analyzed by X-ray diffractometer (XRD) and scanning electron microscope (SEM), and the wear behavior of the coating under different loads was studied by reciprocating friction and wear testing machine and three-dimensional profiler. The surface of the grinding marks was analyzed by SEM and energy density spectrum (EDS). The performance was compared with the anodized film of 4032 aluminum alloy and the Ni-coated coating of 4032 aluminum alloy. The experimental results show that the C-MoS2-PTFE coating has a dense structure, and the hardness is 35 HV0.1. Under dry friction conditions, the C-MoS2-PTFE coating has excellent wear reduction and wear resistance, and the coefficient of friction and wears rate under different loads are less than those of the anodized film of 4032 aluminum alloy and the Ni-plated coating. The wear mechanisms of C-MoS2-PTFE coating are fatigue wear, adhesive wear, abrasive wear, and oxidation wear under different loads.
Improved Mechanical and Corrosion Properties of Powder Metallurgy Austenitic, Ferritic, and Martensitic Stainless Steels by Liquid Phase Sintering
Authors: Ku Ming-Hsiang , Tsao Lung-Chuan , Tsai Yu-Jin , Lin Zih-Jie , Wu Ming-Wei
Published: August 2022

Powder metallurgy (PM) has been widely used to produce various steels in industry, mainly due to its capabilities for manufacturing nearly net-shaped products and mass production. To improve the performances of PM stainless steels, the roles of 0.6 wt% B additive in the microstructures, mechanical properties, and corrosion resistances of PM 304L austenitic, 410L ferritic, and 410 martensitic stainless steels were investigated. The results showed that adding 0.6 wt% B significantly improved the sintered densities of the three kinds of stainless steels due to the liquid phase sintering (LPS) phenomenon. The borides in 304L + 0.6B, 410L + 0.6B, and 410 + 0.6B were rich in B and Cr atoms but deficient in Fe, Ni, or C atoms, as analyzed by electron probe micro-analysis. Furthermore, the B additive contributed to the improved apparent hardness and corrosion resistance of PM stainless steels. In the 410L stainless steel, the 0.6 wt% B addition increased the corrosion voltage from −0.43 VSCE to −0.24 VSCE and reduced the corrosion current density from 2.27 × 10−6 A/cm2 to 1.93 × 10−7 A/cm2. The effects of several factors, namely: porosity; the generation of boride; the matrix/boride interfacial areas; Cr depletion; and the microstructure on the corrosion performances are discussed. The findings clearly indicate that porosity plays a predominant role in the corrosion resistances of PM austenitic, ferritic, and martensitic stainless steels.
Durability and Property Study of Decade Old Crumb Rubber Concrete Cored Specimens
Authors: Duan Fuqiang , Zhu Han , Ibrahim Yasser E. , Adamu Musa
Published: August 2022

Crumb rubber concrete (CRC) is a concrete that contains rubber crumbs. This article presents a study of three experiments on long aged CRC specimens that were cored from a decade old CRC bridge deck in Tianjin, China. The three experimental tests conducted were: (1) the flexural stress–strain test on semi-circular disk specimens; (2) the accelerated steel-rebar corrosion test and (3) the carbonation test. In addition, the in situ carbonation test was also carried out on the CRC bridge deck. The flexural stress–strain test results showed that the CRC semi-circular disk specimens exhibited a ductile pattern and high-energy absorbing capacity with its flexural tensile strength being at 5 MPa and the flexural modulus of 10 GPa. The steel corrosion rust rate via the calculation of steel mass loss before and after the test in the accelerated steel-rebar corrosion test remained extremely low. The carbonation test results showed that in comparison with the prediction of two popular carbonation models, the carbonation in the CRC bridge deck took place at a much slower rate during the last 13 years. All of the results obtained in this study are reported for the first-time and indicate that these CRC cored specimens exhibit good mechanical properties and excellent durability characteristics after a decade in service, which may provide the technical knowledge for the possible future application of CRC in concrete constructions.
Results of a Surface Roughness Comparison between Stylus Instruments and Confocal Microscopes
Authors: Mínguez-Martínez Alberto , Maresca Piera , Caja Jesús , Oliva Jesús de Vicente y
Published: August 2022

This article presents the results of an LMM-R-2019 interlaboratory comparison. Such comparisons of different families of measuring instruments are one of the activities conducted among the calibration laboratories to maintain their ISO 17025 accreditation. Given that the study of surface roughness is becoming increasingly important in the field of dimensional metrology, the comparison focused on determining the Ra parameter on a pseudorandom metallic roughness standard using two types of measuring instruments: physical contact (stylus instruments) and optical (confocal microscopes). Among the aspects studied was whether the roughness measurements obtained using calibrated confocal microscopes could be compared with those using traditional methods since optical instruments obtain measurements more quickly and responsively than do stylus instruments. The results showed that roughness measurements using confocal microscopes are comparable with those from a traditional stylus instrument.
A Novel Method of Si and Si3N4 Powder Resources Recycling: Cold Bonding Briquettes
Authors: Xiong Yuandong , Li Ying , Chen Huiting , Qiu Dejin , Wei Shiyu , Saxén Henrik , Yu Yaowei
Published: August 2022

Silicon nitride (Si3N4) and silicon powder (Si) are two kinds of harmful solid waste in industrial production. As an environmental and low-consumption method, the cold-bonding technique is a novel method to utilize the problem of powder resource cycling. In this experiment, mechanical and high-temperature properties of Si and Si3N4 briquettes were studied after cold bonding. The results are as follows: (1) The compressive strength of the Si and Si3N4 briquettes increased with the improvement of molding pressure. With the same binder (1 wt.%) and water (10 wt.%) addition, the compressive strength of the Si3N4 briquette arrived at 12,023.53 N under 40 Mpa molding pressure, which is much higher than that of the Si briquette (942.40 N). The Si particles are uneven and irregular, which leads to an intense arch bridge effect in the Si briquette and the compressive strength decrease. Compared with Si powder, the particle size and shape of Si3N4 is small, uniform, and regular. The influence of the arch bridge effect is smaller than that in the Si briquette. (2) After being treated at 1473 K for 1 h, the compressive strength of the Si briquette increased to 5049.83 N, and the compressive strength of the Si3N4 briquette had a slight change. The surface of the briquettes was contacted with oxygen and reacted to form an outer shell which mainly contains SiO2 in the high-temperature treatment. FT-IR results have shown there were no extra impurities in cold-bonded briquettes when using the organic binder. (3) The microstructure of the cross section of the Si and Si3N4 briquettes after high-temperature treatment presented that oxygen entered the briquette through the pores and continued to react with the Si and Si3N4. The outer shell of the Si briquette grew and thickened continuously with the oxygen spreading in the Si briquette. However, because of the smaller particle size and regular shape, little oxygen diffused in the Si3N4 briquette. The outer shell of the Si3N4 briquette is fairly thin, so the compressive strength did not change too much.
Design and Experimental Evaluation of an In-Wheel Flux-Switching Machine for Light Vehicle Application
Authors: Mendonça Gabriel A. , Galo Diogo P. V. , Sales Luís Carlos M. , Cardoso Filho Braz J. , Maia Thales A. C.
Published: August 2022

Restrictive regulations regarding emissions and fossil fuel consumption lead to the electric vehicle being an alternative to replace conventional internal combustion engine vehicles. The pure electric powertrain technology and the charging infrastructure are still immature in some markets, where increasing the overall vehicle efficiency by energy harvesting means can be a more viable solution. This paper presents the design and experimental validation of an in-wheel flux-switching machine for regenerative braking in a light passenger vehicle. Later, the energy can be used for fuel handling and reforming, performance enhancement, increasing efficiency, and reducing emissions. Feasibility and technological challenges are also discussed. The Maxwell–Fourier method and a novel steady-state equivalent circuit presented in this paper are used for geometry sensitivity analysis and optimization routine.
Design and Load Distribution Analysis of the Mismatched Cycloid-Pin Gear Pair in RV Speed Reducers
Authors: Li Xuan , Tang Linggao , He Haidong , Sun Lining
Published: August 2022

The current loaded tooth contact analysis of cycloid drives based on the assumption of theoretical positions of ring pins ignores the deviations caused by manufacturing errors and elastic deformations, which are not in agreement with reality. To fill this gap, an improved load distribution model of the mismatched cycloid-pin gear pair with ring pin position deviations is presented for a component-level analysis. Firstly, with the cycloid gear tooth profile geometry defined, the unloaded tooth contact analysis is applied as a pre-processor to determine the potential contact points, the gear backlash, and the rotation angle of the cycloid gear. Secondly, due to the statically indeterminate structure of the multi-tooth contact, a varying nonlinear contact stiffness is introduced to establish the relation between force and deformation. Then, the force and moment equilibrium equations with compatibility conditions are solved by using an iterative approach. With this, detailed parametric case studies are presented to verify the correctness of the proposed model by comparing it with those predicted by the current model and to demonstrate the influences of ring pin position deviations on the distributed load, contact stress, loaded transmission error, and instantaneous gear ratio of the mismatched cycloid-pin gear pair. This study provides a deeper investigation into the load distribution characteristics of the cycloid drive and therefore can be employed to assist in gear design.
Mechanism Design and Performance Analysis of a Sitting/Lying Lower Limb Rehabilitation Robot
Authors: Dong Fangyan , Li Haoyu , Feng Yongfei
Published: August 2022

To meet the various need of stroke patients’ rehabilitation training and carry out complex task training in real scenes, the structure of a lower limb rehabilitation robot with movements in the sagittal plane and coronal plane is usually complicated. A new sitting/lying lower limb rehabilitation robot (LOBO) with a simple mechanism form is proposed, which is designed based on a 2-PRR parallel mechanism. First, the kinematics, singularity, and condition number of the 2-PRR parallel mechanism are analyzed, which provides the basis for mechanism parameter design. Then, through the proportional–derivative control principle, real-time tracking of LOBO’s designed trajectory is realized. Finally, the length parameters of volunteers’ lower limbs are collected, and experimental verification is conducted in LOBO’s passive training mode. The experimental results show the feasibility of LOBO’s movement in the human sagittal and coronal planes. LOBO will help human lower limbs realize the synchronous continuous rehabilitation training of hip, knee, and ankle joints spatially, which could drive the rehabilitation movement of patients’ lower limbs in the sagittal plane and coronal plane in future clinical research. LOBO can also be applied to muscle strength training for the elderly to combat the effects of aging.
Millimeter-Wave Radar and Vision Fusion Target Detection Algorithm Based on an Extended Network
Authors: Qi Chunyang , Song Chuanxue , Zhang Naifu , Song Shixin , Wang Xinyu , Xiao Feng
Published: August 2022

The need for a vehicle to perceive information about the external environmental as an independent intelligent individual has grown with the progress of intelligent driving from primary driver assistance to high-level autonomous driving. The ability of a common independent sensing unit to sense the external environment is limited by the sensor’s own characteristics and algorithm level. Hence, a common independent sensing unit fails to obtain comprehensive sensing information independently under conditions such as rain, fog, and night. Accordingly, an extended network-based fusion target detection algorithm for millimeter-wave radar and vision fusion is proposed in this work by combining the complementary perceptual performance of in-vehicle sensing elements, cost effectiveness, and maturity of independent detection technologies. Feature-level fusion is first used in this work according to the analysis of technical routes of the millimeter-wave radar and vision fusion. Training and test evaluation of the algorithm are carried out on the nuScenes dataset and test data from a homemade data acquisition platform. An extended investigation on the RetinaNet one-stage target detection algorithm based on the VGG-16+FPN backbone detection network is then conducted in this work to introduce millimeter-wave radar images as auxiliary information for visual image target detection. We use two-channel radar and three-channel visual images as inputs of the fusion network. We also propose an extended VGG-16 network applicable to millimeter-wave radar and visual fusion and an extended feature pyramid network. Test results showed that the mAP of the proposed network improves by 2.9% and the small target accuracy is enhanced by 18.73% compared with those of the reference network for pure visual image target detection. This finding verified the detection capability and algorithmic feasibility of the proposed extended fusion target detection network for visually insensitive targets.
Study on the Factors Affecting the Wheel–Rail Lateral Impact of the Forepart of the Curved Switch Rail
Authors: Liao Bo , Luo Yanyun
Published: August 2022

In the switch rail section of a high-speed turnout, the wheel–rail lateral impact of the forepart of the curved switch rail is the most important factor affecting the passing performance. In order to reduce the lateral impact and improve the passing safety, a complete vehicle–track multi-body dynamics model is devised in this paper. The variation of the wheel–rail relationship when the train passes through is analyzed. The lateral force and derailment coefficient are calculated under different parameters, and the wear index is also calculated under some working conditions. The results show that properly reducing the lateral damping of the curved switch rail can effectively reduce the wheel–rail lateral force and derailment coefficient of this section, while keeping the track shape undamaged. The optimization of rail cant design plays an important role in alleviating lateral wheel–rail impact. Decreasing the height reduction of the switch rail is helpful to optimize the lateral force of the forepart of the curved switch rail. The selection of a suitable cutting mode for switch blade and reasonable control of the wheel–rail impact angle as well as passing speed have positive effects on controlling the lateral wheel–rail impact of the forepart of the curved switch rail.
A Matrix Spline Method for a Class of Fourth-Order Ordinary Differential Problems
Authors: Tung Michael , Defez Emilio , Ibáñez Javier , Alonso José , Real-Herráiz Julia
Published: August 2022

Differential matrix models provide an elementary blueprint for the adequate and efficient treatment of many important applications in science and engineering. In the present work, we suggest a procedure, extending our previous research results, to represent the solutions of nonlinear matrix differential problems of fourth order given in the form Y(4)(x)=f(x,Y(x)) in terms of higher-order matrix splines. The corresponding algorithm is explained, and some numerical examples for the illustration of the method are included.
Fractional-Order Memristive Wilson Neuron Model: Dynamical Analysis and Synchronization Patterns
Authors: Vivekanandan Gayathri , Mehrabbeik Mahtab , Natiq Hayder , Rajagopal Karthikeyan , Tlelo-Cuautle Esteban
Published: August 2022

Fractional nonlinear systems have been considered in many fields due to their ability to bring memory-dependent properties into various systems. Therefore, using fractional derivatives to model real-world phenomena, such as neuronal dynamics, is of significant importance. This paper presents the fractional memristive Wilson neuron model and studies its dynamics as a single neuron. Furthermore, the collective behavior of neurons is researched when they are locally and diffusively coupled in a ring topology. It is found that the fractional-order neurons are bistable in some values of the fractional order. Additionally, complete synchronization, lag synchronization, phase synchronization, and sine-like synchronization patterns can be observed in the constructed network with different fractional orders.
Weighted Mean Inactivity Time Function with Applications
Authors: Di Crescenzo Antonio , Toomaj Abdolsaeed
Published: August 2022

We consider an extension of the mean inactivity time based on a non-negative weight function. We show various properties of the new notion, and relate it to various functions of interest in reliability theory and information measures, such as the dynamic cumulative entropy, the past entropy, the varentropy, and the weighted cumulative entropy. Moreover, based on the comparison of weighted mean inactivity times, we introduce and study a new stochastic order and compare it with other suitable orders. We also discuss some results about the variance of transformed random variables and the weighted generalized cumulative entropy. Then, we investigate certain connections with the location-independent riskier order. Finally, we pinpoint several characterizations and preservation properties of the new stochastic order under shock models, random maxima, and notions of renewal theory.
A Thermal-Hydrological-Mechanical-Chemical Coupled Mathematical Model for Underground Coal Gasification with Random Fractures
Authors: Zhang Zhizhen , Yang Xiao , Shang Xiaoji , Yang Huai
Published: August 2022

In this paper, in order to understand the development process and influencing factors of coal underground gasification, taking the two-dimensional underground gasification area of the plane as the simulation object, the characteristics of the multi-physical field coupling process of exudate mass heat transfer and combustion gasification reaction in the process of horizontal coal seam underground gasification are analyzed, and a two-dimensional mathematical model of thermal-hydrological-mechanical-chemical coupling of a porous medium is established. The temperature distribution of coal rock from the gasification point, the distribution of gas water vapor pressure and stress-strain, the temperature contour distribution of fractured coal rocks of different densities of heterogeneity, and the influence of different water-oxygen ratios and different fractured coal rocks on the gas components generated by the gasification reaction were studied. The results show that the tensile damage caused by the tensile strain volume expansion of the coal underground gasification center, the shear damage caused by the compression of the edge compressive strain volume, and the temperature conduction rate decrease with the increase in the coal rock fracture, but in the heterogeneous coal rock, the greater the fracture density, the faster the temperature conduction rate, which has a certain impact on the gasification combustion reaction. The ratio of CO2, H2 and CO in the case of simulating that the water-to-oxygen ratio is 1:2, 1:1, and 2:1 is 1:0.85:0.73, 1:1.1:0.97, and 1:1.76:1.33, respectively. At a water-oxygen ratio of 2:1, the concentration ratio is the most ideal, and the main gases, CO, CO2, and H2, are 32%, 21%, and 37%. Furthermore, the reaction rate increases with the increase of fracture density. The gas component concentration simulated in this paper has good consistency with the results of the previous experimental data, which has important guiding significance for the underground coal gasification project.
Mathematical Modelling of Harmful Algal Blooms on West Coast of Sabah
Authors: Yussof Fatin Nadiah , Maan Normah , Md Reba Mohd Nadzri , Khan Faisal Ahmed
Published: August 2022

Algal bloom is a condition in which there is a massive growth of algae in a certain region and it is said to be harmful when the bloom causes damage effects. Due to the tremendous impact of harmful algal bloom (HAB) on some aspects, this research proposes the mathematical modelling of an HAB model to describe the process of HAB together with population dynamics. This research considers the delay terms in the modelling since the liberation of toxic chemicals by toxin-producing phytoplankton (TPP) is not an instantaneous process in which the species need to achieve their maturity. A model of fish interaction is also being studied to show the effect of HAB on fish species. Time delay is incorporated for the mortality of fish due to the consumption of toxic zooplankton. Stability analysis is conducted and numerical simulations are applied to obtain the analytical results which highlight the critical values for the delay parameters. The existence of Hopf bifurcation is established when the delay passes the threshold value. The results of both models show that the inclusion of the delay term affects the model by stabilizing and destabilizing the model. Therefore, this research shows the effect of an inclusion delay term on the model and also gives knowledge and an understanding of the process of HAB occurrence as well as the effect of HAB on fish populations.
System of Generalized Variational Inclusions Involving Cayley Operators and XOR-Operation in q-Uniformly Smooth Banach Spaces
Authors: Iqbal Javid , Rajpoot Arvind Kumar , Islam Monirul , Ahmad Rais , Wang Yuanheng
Published: August 2022

In this paper, we consider and study a system of generalized variational inclusions involving Cayley operators and an XOR-operation in q-uniformly smooth Banach spaces. To obtain the solution of the system of generalized variational inclusions involving Cayley operators and an XOR-operation, we use some properties of Cayley operators as well as an XOR-operation. We also discuss the convergence criterion. In support of our main result, we provide an example.
Parabolic Hessian Equations Outside a Cylinder
Authors: Dai Limei , Guo Xuewen
Published: August 2022

In this article, we mainly review the parabolic Hessian equation on the exterior region. The existence and uniqueness of solutions with asymptotic properties to the exterior problem of the parabolic Hessian equation were obtained by using the Perron method.
Secure Group Communications Using Twisted Group Rings
Authors: Gómez Olvera María Dolores , López Ramos Juan Antonio , Torrecillas Jover Blas
Published: August 2022

In this paper we introduce a Group Key Management protocol following the idea of the classical protocol that extends the well-known Diffie–Hellman key agreement to a group of users. The protocol is defined in a non-commutative setting, more precisely, in a twisted dihedral group ring. The protocol is defined for an arbitrary cocycle, extending previous key agreements considered for two users. The main objective of this work is to show that there is no lack of security derived from the fact that a larger amount of public information is known by an external observer.
Topic Network Analysis Based on Co-Occurrence Time Series Clustering
Authors: Lin Weibin , Wu Xianli , Wang Zhengwei , Wan Xiaoji , Li Hailin
Published: August 2022

Traditional topic research divides similar topics into the same cluster according to clustering or classification from the perspective of users, which ignores the deep relationship within and between topics. In this paper, topic analysis is achieved from the perspective of the topic network. Based on the initial core topics obtained by the keyword importance and affinity propagation clustering, co-occurrence time series between topics are constructed according to time sequence and topic frequency. Subsequence segments of each topic co-occurrence time series are divided by sliding windows, and the similarity between subsequence segments is calculated. Based on the topic similarity matrix, the topic network is constructed. The topic network is divided according to the community detection algorithm, which realizes the topic re-clustering and reveals the deep relationship between topics in fine-grained. The results show there is no relationship between topic center representation and keyword popularity, and topics with a wide range of concepts are more likely to become topic network centers. The proposed approach takes into account the influence of time factors on topic analysis, which not only expands the analysis in the field of topic research but also improves the quality of topic research.
Design and Control Strategy of Soft Robot Based on Gas–Liquid Phase Transition Actuator
Authors: Lin Guojian , Huang Wenkai , Hu Chuanshuai , Xiao Junlong , Zhou Fobao , Zhang Xiaolin , Liang Jiajian , Liang Jiaqiao
Published: August 2022

In this paper, a soft robot driven by a gas–liquid phase transition actuator with a new structure is designed; The soft robot is driven by the pressure generated by electrically induced ethanol phase transition. The gas–liquid phase transition drive was found to be able to generate a larger driving force by using only low voltage. Compared with the gas drive of a traditional soft robot, gas–liquid phase transition-driven soft robot does not require a complex circuit system and a huge external energy supply air pump, making its overall structure more compact. At the same time, because of the new structure of the actuator on the soft robot, the soft robot has good gas tightness and less recovery time. A reinforcement depth learning control strategy is also added so that the soft robot with this actuator could better grip objects of different sizes and weights.
On the Forced Vibration of Bending-Torsional-Warping Coupled Thin-Walled Beams Carrying Arbitrary Number of 3-DoF Spring-Damper-Mass Subsystems
Authors: Chen Jun , Liu Xiang
Published: August 2022

This paper presents an analytical transfer matrix modeling framework for the forced vibration of a bending-torsional-warping coupling Euler-Bernoulli thin-walled beam carrying an arbitrary number of three degree-of-freedom (DOF) spring-damper-mass (SDM) subsystems. The thin-walled beam is divided into a series of distinct sub-beams whose ends are connected to the SDM subsystems. The transfer matrix for each sub-beam is developed based on the exact shape functions of the bending-torsional-warping coupling Euler-Bernoulli theory. Each SDM system is modelled by a set of effective springs based on the dynamic condensation method. The governing matrix equation is formulated based on the compatibility conditions of the placement and the force at the common interfaces of two adjacent sub-beams. Then, a closed-form expression for the frequency response function of the thin-walled beam system is proposed. The results computed by the proposed method achieve good agreement with those obtained by the conventional finite-element method, which shows the accuracy and reliability of the proposed method. The effects of the system parameters on the vibration transmission and vibration isolation properties of the thin-walled beam system are studied. The presented method can simultaneously consider arbitrary number of SDM subsystems and boundary conditions. Furthermore, none of the associated matrices are larger than 12 × 12, which provides a significant computational advantage.
Influence of Binomial Crossover on Approximation Error of Evolutionary Algorithms
Authors: Wang Cong , He Jun , Chen Yu , Zou Xiufen
Published: August 2022

Although differential evolution (DE) algorithms perform well on a large variety of complicated optimization problems, only a few theoretical studies are focused on the working principle of DE algorithms. To make the first attempt to reveal the function of binomial crossover, this paper aims to answer whether it can reduce the approximation error of evolutionary algorithms. By investigating the expected approximation error and the probability of not finding the optimum, we conduct a case study comparing two evolutionary algorithms with and without binomial crossover on two classical benchmark problems: OneMax and Deceptive. It is proven that using binomial crossover leads to the dominance of transition matrices. As a result, the algorithm with binomial crossover asymptotically outperforms that without crossover on both OneMax and Deceptive, and outperforms on OneMax, however, not on Deceptive. Furthermore, an adaptive parameter strategy is proposed which can strengthen the superiority of binomial crossover on Deceptive.
AI-Empowered Attack Detection and Prevention Scheme for Smart Grid System
Authors: Kumari Aparna , Patel Rushil Kaushikkumar , Sukharamwala Urvi Chintukumar , Tanwar Sudeep , Raboaca Maria Simona , Saad Aldosary , Tolba Amr
Published: August 2022

The existing grid infrastructure has already begun transforming into the next-generation cyber-physical smart grid (SG) system. This transformation has improved the grid’s reliability and efficiency but has exposed severe vulnerabilities due to growing cyberattacks and threats. For example, malicious actors may be able to tamper with system readings, parameters, and energy prices and penetrate to get direct access to the data. Several works exist to handle the aforementioned issues, but they have not been fully explored. Consequently, this paper proposes an AI-ADP scheme for the SG system, which is an artificial intelligence (AI)-based attack-detection and prevention (ADP) mechanism by using a cryptography-driven recommender system to ensure data security and integrity. The proposed AI-ADP scheme is divided into two phases: (i) attack detection and (ii) attack prevention. We employed the extreme gradient-boosting (XGBoost) mechanism for attack detection and classification. It is a new ensemble learning methodology that offers many advantages over similar methods, including built-in features, etc. Then, SHA-512 is used to secure the communication that employs faster performance, allowing the transmission of more data with the same security level. The performance of the proposed AI-ADP scheme is evaluated based on various parameters, such as attack-detection accuracy, cycles used per byte, and total cycles used. The proposed AI-ADP scheme outperformed the existing approaches and obtained 99.12% accuracy, which is relatively high compared to the pre-existing methods.
Significance of the Coriolis Force on the Dynamics of Carreau–Yasuda Rotating Nanofluid Subject to Darcy–Forchheimer and Gyrotactic Microorganisms
Authors: Ahmad Bilal , Ahmad Muhammad , Ali Liaqat , Ali Bagh , Hussein Ahmed , Shah Nehad , Chung Jae
Published: August 2022

In this study, the significance of the Coriolis force on the dynamics of Carreau—Yasuda flow toward a continuously stretched surface subject to the Darcy–Forchheimer law is investigated. The nanoparticles are incorporated due to their unusual characteristics (e.g., extraordinary thermal conductivity), which are significant in heat exchangers and advanced nanotechnology. To avoid possible sedimentation of tiny particles, the gyrotactic microorganisms must be incorporated. The goal of this research was to find out the dynamics of three-dimensional rotational flow for nanofluids under the influence of Darcy–Forchheimer with the thermophoresis effect and motile microorganisms. The equations governing mass, momentum, and energy equations are formalized using partial derivatives, which may subsequently be transformed into dimensionless differential shapes using the personifications of apposite similarity transformations. The MATLAB application bvp4c was used in conjunction with a shooting technique to solve a nonlinear mathematical model based on ordinary differential equations. It was observed that the base fluid velocities decreased against higher input of rotation and porosity parameters; moreover, the Brownian motion and thermophoresis increased the temperature profile.
The Stochastic Team Orienteering Problem with Position-Dependent Rewards
Authors: Panadero Javier , Barrena Eva , Juan Angel A. , Canca David
Published: August 2022

In this paper, we analyze both the deterministic and stochastic versions of a team orienteering problem (TOP) in which rewards from customers are dynamic. The typical goal of the TOP is to select a set of customers to visit in order to maximize the total reward gathered by a fixed fleet of vehicles. To better reflect some real-life scenarios, we consider a version in which rewards associated with each customer might depend upon the order in which the customer is visited within a route, bonusing the first clients and penalizing the last ones. In addition, travel times are modeled as random variables. Two mixed-integer programming models are proposed for the deterministic version, which is then solved using a well-known commercial solver. Furthermore, a biased-randomized iterated local search algorithm is employed to solve this deterministic version. Overall, the proposed metaheuristic algorithm shows an outstanding performance when compared with the optimal or near-optimal solutions provided by the commercial solver, both in terms of solution quality as well as in computational times. Then, the metaheuristic algorithm is extended into a full simheuristic in order to solve the stochastic version of the problem. A series of numerical experiments allows us to show that the solutions provided by the simheuristic outperform the near-optimal solutions obtained for the deterministic version of the problem when the latter are used in a scenario under conditions of uncertainty. In addition, the solutions provided by our simheuristic algorithm for the stochastic version of the problem offer a higher reliability level than the ones obtained with the commercial solver.