bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy-Efficient Adaptive Sensing Scheduling in Wireless Sensor Networks Using Fibonacci Tree Optimization Algorithm
Authors: Wu Liangshun , Cai Hengjin
Published: July 2021

Wireless sensor networks are appealing, largely because they do not need wired infrastructure, but it is precisely this feature that renders them energy-constrained. The duty cycle scheduling is perceived as a contributor to the energy efficiency of sensing. This paper developed a novel paradigm for modeling wireless sensor networks; in this context, an adaptive sensing scheduling strategy is proposed depending on event occurrence behavior, and the scheduling problem is framed as an optimization problem. The optimization objectives include reducing energy depletion and optimizing detection accuracy. We determine the explicit form of the objective function by numerical fitting and found that the objective function aggregated by the fitting functions is a bivariate multimodal function that favors the Fibonacci tree optimization algorithm. Then, with the optimal parameters optimized by the Fibonacci tree optimization algorithm, the scheduling scheme can be easily deployed, and it behaves consistently in the coming hours. The proposed “Fibonacci Tree Optimization Strategy” (“FTOS”) outperforms lightweight deployment-aware scheduling (LDAS), balanced-energy scheduling (BS), distributed self-spreading algorithm (DSS) and probing environment and collaborating adaptive sleeping (PECAS) in achieving the aforementioned scheduling objectives. The Fibonacci tree optimization algorithm has attained a better optimistic effect than the artificial bee colony (ABC) algorithm, differential evolution (DE) algorithm, genetic algorithm (GA) algorithm, particle swarm optimization (PSO) algorithm, and comprehensive learning particle swarm optimization (CLPSO) algorithm in multiple runs.
Machine Learning Approach for Fatigue Estimation in Sit-to-Stand Exercise
Authors: Aguirre Andrés , Pinto Maria J. , Cifuentes Carlos A. , Perdomo Oscar , Díaz Camilo A. R. , Múnera Marcela
Published: July 2021

Physical exercise (PE) has become an essential tool for different rehabilitation programs. High-intensity exercises (HIEs) have been demonstrated to provide better results in general health conditions, compared with low and moderate-intensity exercises. In this context, monitoring of a patients’ condition is essential to avoid extreme fatigue conditions, which may cause physical and physiological complications. Different methods have been proposed for fatigue estimation, such as: monitoring the subject’s physiological parameters and subjective scales. However, there is still a need for practical procedures that provide an objective estimation, especially for HIEs. In this work, considering that the sit-to-stand (STS) exercise is one of the most implemented in physical rehabilitation, a computational model for estimating fatigue during this exercise is proposed. A study with 60 healthy volunteers was carried out to obtain a data set to develop and evaluate the proposed model. According to the literature, this model estimates three fatigue conditions (low, moderate, and high) by monitoring 32 STS kinematic features and the heart rate from a set of ambulatory sensors (Kinect and Zephyr sensors). Results show that a random forest model composed of 60 sub-classifiers presented an accuracy of 82.5% in the classification task. Moreover, results suggest that the movement of the upper body part is the most relevant feature for fatigue estimation. Movements of the lower body and the heart rate also contribute to essential information for identifying the fatigue condition. This work presents a promising tool for physical rehabilitation.
Crack Size Identification for Bearings Using an Adaptive Digital Twin
Authors: Piltan Farzin , Kim Jong-Myon
Published: July 2021

In this research, the aim is to investigate an adaptive digital twin algorithm for fault diagnosis and crack size identification in bearings. The main contribution of this research is to design an adaptive digital twin (ADT). The design of the ADT technique is based on two principles: normal signal modeling and estimation of signals. A combination of mathematical and data-driven techniques will be used to model the normal vibration signal. Therefore, in the first step, the normal vibration signal is modeled to increase the reliability of the modeling algorithm in the ADT. Then, to help challenge the complexity and uncertainty, the data-driven method will solve the problems of the mathematically based algorithm. Thus, first, Gaussian process regression is selected, and then, in two steps, we improve its resistance and accuracy by a Laguerre filter and fuzzy logic algorithm. After modeling the vibration signal, the second step is to design the data estimation for ADT. These signals are estimated by an adaptive observer. Therefore, a proportional-integral observer is then combined with the proposed technique for signal modeling. Then, in two stages, its robustness and reliability are strengthened using the Lyapunov-based algorithm and adaptive technique, respectively. After designing the ADT, the residual signals that are the difference between original and estimated signals are obtained. After that, the residual signals are resampled, and the root means square (RMS) signals are extracted from the residual signals. A support vector machine (SVM) is recommended for fault classification and crack size identification. The strength of the proposed technique is tested using the Case Western Reserve University Bearing Dataset (CWRUBD) under diverse torque loads, various motor speeds, and different crack sizes. In terms of fault diagnosis, the average detection accuracy in the proposed scheme is 95.75%. In terms of crack size identification for the roller, inner, and outer faults, the proposed scheme has average detection accuracies of 97.33%, 98.33%, and 98.33%, respectively.
The ‘Ride’ Feeling during Running under Field Conditions—Objectified with a Single Inertial Measurement Unit
Authors: Bräuer Sabrina , Kiesewetter Pierre , Milani Thomas L. , Mitschke Christian
Published: July 2021

Foot rollover and the ‘ride’ feeling that occurs during heel–toe transition during running have been investigated mostly in laboratory settings due to the technical requirements of ‘golden standard’ measurement devices. Hence, the purpose of the current study was to investigate ‘ride’ and rollover with a heel cap-mounted inertial measurement unit (IMU) when running under field conditions to get realistic results. Twenty athletes ran on a 1 km outdoor track with five different shoe conditions, only differing in their midsole bending stiffness. The peak angular velocity (PAV) in the sagittal plane of the shoe was analyzed. The subjective evaluation of the ‘ride’ perception during heel–toe transition was rated on a visual analogue scale. The results revealed that PAV and ‘ride’ varied for the different shoes. The regression analysis showed that PAV has a significant impact on the ‘ride’ rating (R2 = 0.952; p = 0.005). The shoe with a medium midsole bending stiffness had the lowest value for PAV (845.6 deg/s) and the best rating of perceived ‘ride’ on average. Our results show that IMU can be used as a low-cost method to investigate the heel–toe transition during field-running. In addition, we found that midsole bending stiffness influenced PAV and the subjective feeling of ‘ride’.
Deep Learning for Efficient and Optimal Motion Planning for AUVs with Disturbances
Authors: Parras Juan , Apellániz Patricia A. , Zazo Santiago
Published: July 2021

We use the recent advances in Deep Learning to solve an underwater motion planning problem by making use of optimal control tools—namely, we propose using the Deep Galerkin Method (DGM) to approximate the Hamilton–Jacobi–Bellman PDE that can be used to solve continuous time and state optimal control problems. In order to make our approach more realistic, we consider that there are disturbances in the underwater medium that affect the trajectory of the autonomous vehicle. After adapting DGM by making use of a surrogate approach, our results show that our method is able to efficiently solve the proposed problem, providing large improvements over a baseline control in terms of costs, especially in the case in which the disturbances effects are more significant.
Time-Domain and Monostatic-like Frequency-Domain Methods for Bistatic SAR Simulation
Authors: Di Martino Gerardo , Iodice Antonio , Natale Antonio , Riccio Daniele
Published: July 2021

In recent years, an increasing interest has been devoted to bistatic SAR configurations, which can be effectively used to improve system performance and/or to increase the amount of physical information retrievable from the observed scene. Within this context, the availability of simulation tools is of paramount importance, for both mission planning and processing algorithm verification and testing. In this paper, a time domain simulator useful to obtain the point-spread function and the raw signal for the generic bistatic SAR configuration is presented. Moreover, we focus on the case of two bistatic configurations, which are of considerable interest in actual SAR applications, i.e., the translational invariant SAR and the one-stationary SAR acquisition geometries, for which we obtain meaningful expressions of the Transfer Functions. In particular, these expressions are formally equal to those obtained for the monostatic SAR configuration, so that the already available monostatic simulator can be easily adapted to these bistatic cases. The point-target raw signals obtained using the (exact) time domain simulator and the (approximated) frequency domain one are compared, with special attention to acquisition geometries that may be of practical interest in Formation-Flying SAR applications. Results show that the phase difference between raw signals simulated with the two approaches is, in all cases, smaller (and often much smaller) than about 10 degrees, except that at the very edge of the raw signals, where however, it does not exceed about 50 degrees.
Algebraic Connectivity Control in Distributed Networks by Using Multiple Communication Channels
Authors: Griparić Karlo
Published: July 2021

The effectiveness of collaboration in distributed networks, such as sensor networks and multi-agent systems, relies on nodes’ ability to exchange information. The availability of various communication protocols with different technical properties opens the possibility to guarantee connectivity during a system’s operation in any condition. A communication network can be represented by a graph on which connectivity can be expressed by a well-known algebraic connectivity value or Fiedler value. It is one of the most important tools used in many applications where connectivity preservation is required. In this paper, a trust-based consensus algorithm for algebraic connectivity estimation has been implemented. To guarantee the accomplishment of the global objective and the system’s performance, our contributions include: (i) a novel decentralized framework for combining multiple communication channels in a resulting channel and (ii) a decentralized algebraic connectivity control law that dynamically changes the number of agents in the system during operation. The proposed algebraic connectivity control strategy has been evaluated in simulations and in a real multi-robot system using two channels with different properties and initial topologies.
Physical, Physiological, and Technical Demands in Ultimate Frisbee Small-Sided Games: Influence of Pitch Size
Authors: Kajiki Masanobu , Yamashita Yuto , Inada Ryosuke , Matsumoto Takaaki
Published: July 2021

Small-sided games (SSGs) are common drills used in various team sports, but the exercise intensity in ultimate Frisbee SSG has not yet been investigated. To clarify the physical, physiological, and technical demands of ultimate Frisbee SSG, we investigated the influence of pitch size on exercise intensity during SSG. Nine male college ultimate Frisbee players played (3 vs. 3) SSG on small (SSGS: 30 × 15 m) and large (SSGL: 40 × 20 m) pitches; both SSGs comprised of four 4 min periods, interspersed by 5 min of passive recovery. Players’ mean heart rate (170 ± 8 and 171 ± 7 bpm), peak heart rate (184 ± 7 and 184 ± 5 bpm), and blood lactate concentration (11.3 ± 4.7 and 11.8 ± 4.6 mmol/L) were similar in SSGS and SSGL, respectively. The total distance covered (1984 ± 166 m and 1702 ± 80 m) and the distance covered during quick (860 ± 112 m and 696 ± 69 m) and high-intensity running (439 ± 95 and 255 ± 44) in SSGL were significantly longer than those in SSGS (p < 0.05). Conversely, the number of accelerations (45 ± 3 and 41 ± 3) and decelerations (44 ± 3 and 40 ± 4), catching errors (2 ± 1 and 1 ± 1), and turnovers (8 ± 2 and 6 ± 2) in SSGS were significantly greater than those in SSGL (p < 0.05). This study suggests that ultimate Frisbee SSG provides high-intensity training, which stimulates the glycolytic pathway. Furthermore, manipulating SSG pitch size effectively modulates the physical demands of SSG.
Assessment of Regional Fisheries Management Organizations Efforts toward the Precautionary Approach and Science-Based Stock Management and Compliance Measures
Authors: Ogawa Mervin , Reyes Joseph Anthony L.
Published: July 2021

The sustainable management of the ocean as a global food source has been prominent in recent debates due to the disproportionate rate of human consumption, depletion of fish stocks and shortcomings in conservation efforts. Criticisms from various sectors on the effectiveness of Regional Fisheries Management Organizations (RFMO) in relation to their mandates have prompted performance reviews (PRs) to evaluate their efforts in fisheries management. Among concerns are slow implementation of comprehensive harvest strategies which use science-based indicators and management principles. Moreover, RFMOs are expected to apply the precautionary approach, in the hopes of anticipating, monitoring, preventing and mitigating potential threats. The emergent themes are revealed through content analysis pertaining to cooperation and compliance being essential to fisheries management activities in conjunction with choosing the right operational approaches and the proper implementation of various fisheries regulations. Government mandates and stakeholder’s recommendations support fisheries management organizations to function more effectively. This article discusses the role of coercive, normative and mimetic pressures in RFMOs activities, as described in recent performance reviews. It then analyses how RFMOs have implemented the precautionary approach together with science-based stock management and compliance measures, utilizing recent PRs to assess progress on relevant recommendations.
Is There Coupling Effect between Financial Support and Improvement of Human Settlement? A Case Study of the Middle and Lower Regions of the Yangtze River, China
Authors: Yan Weimin , Peng Benhong , Wei Guo , Wan Anxia
Published: July 2021

Currently, there are opposing views on the issue of whether financial support plays a role in improving the human settlement. This article is dedicated to exploring the mutual influence of financial support and the improvement of human settlements from the perspective of coupling effects, and determining the characteristics of coupling and coordination to promote the sustainable development of China and developing countries. This paper uses the entropy method and the coupling coordination model to estimate the coupling and coordination types of financial support and human settlements in seven provinces in the middle and lower reaches of the Yangtze River from 2005 to 2018. In addition, the spatial autocorrelation model is adopted to determine the spatial agglomeration characteristics of the coupling and coordination of financial support and human settlements. All in all, this paper believes that financial support has improved the human settlements, and that there is a coupling effect. Specifically, the coupling coordination value of financial support and human settlements fluctuated from 0.034 to 0.436, showing an inverted U-shaped development trend as a whole. In addition, the correlation between financial support and the improvement of the human settlements is currently in the stage of barely balanced development, and there is a gap between benign and coordinated development. Secondly, the coupling and coordination between financial support and human settlements has significant spatial agglomeration characteristics, and the coupling effect in the eastern region is weaker than that in the western region. In particular, Jiangxi was mainly distributed as high to high agglomeration, and Jiangsu was mainly distributed as high to low agglomeration. It has formed a coupling and coordinated development area with Jiangsu-Jiangxi as the axis, radiating the development of adjacent areas. This research reveals the heterogeneity of financial support to the improvement of human settlements in different regions, portrays the coupling characteristics of financial support and the improvement of human settlements, and provides ideas for the coordinated development of the two.
Data Usage and the Legal Stability of Transactions for the Commercial Operation of Autonomous Vessels Based on Digital Ownership in Korean Civil Law
Authors: Lee Changhee , Kim Yulseong , Shin Youngran
Published: July 2021

Stakeholders in the maritime industry have agreed to expand commercial operations by developing autonomous vessels, the epitome of innovative technologies. However, they are still concerned about the risks of infringing on the rights and interests of individuals or organizations linked to data transactions. Based on Locke’s theory of property ownership, and the assurance of absolute ownership as specified in the Constitution of the Republic of Korea, the business model is still in its early stages. This study examined the concept, transaction structure, and application scope of data activating digital platforms to support data transactions, and aid in advancing the new business sector for commercial operations of maritime autonomous surface ships (MASSs). Consequently, this study contributes to and recognizes the future value of knowledge and intellectual property related to maritime data. This is achieved by defining the intellectual property emerging from newer avenues, such as MASSs, blockchain technology, and smart ports, that are consequential to the rapid development of the maritime industry.
Pt(dithiolene)-Based Colorimetric Chemosensors for Multiple Metal-Ion Sensing
Authors: Son Heawon , Jang Seohyeon , Lim Gayoung , Kim Taeyong , Nam Inho , Noh Dong-Youn
Published: July 2021

Colorimetric chemosensors are widely employed for in-field analysis to detect transition metal ions in real-time with the naked eye. Colorimetric chemosensors have attracted considerable attention because they can conveniently provide quantitative and qualitative information at a low cost. However, the development of colorimetric chemosensors for multiple-ion sensing where metal cations coexist has been limited. For this reason, we developed a new type of transition metal ion sensing material by selectively replacing functional groups on (diphosphine)Pt(dmit) molecules. The terminal groups of the diphosphine ligand were successfully substituted by the cyclohexyl groups, increasing the electron density of the thione moiety. Due to the electron donation ability of the cyclohexyl terminal groups, the proposed chemosensing material was able to selectively detect the mixture of Hg2+, Cu2+, and Ag+ in the presence of many types of interfering cations. To gain insight into the binding mechanisms between the metal ions and the developed (dchpe)Pt(dmit) molecule, density functional theory calculations were also performed.
An Analysis of the Potential for the Formation of ‘Nodes of Persisting Complexity’
Authors: King Nick , Jones Aled
Published: July 2021

Human civilisation has undergone a continuous trajectory of rising sociopolitical complexity since its inception; a trend which has undergone a dramatic recent acceleration. This phenomenon has resulted in increasingly severe perturbation of the Earth System, manifesting recently as global-scale effects such as climate change. These effects create an increased risk of a global ‘de-complexification’ (collapse) event in which complexity could undergo widespread reversal. ‘Nodes of persisting complexity’ are geographical locations which may experience lesser effects from ‘de-complexification’ due to having ‘favourable starting conditions’ that may allow the retention of a degree of complexity. A shortlist of nations (New Zealand, Iceland, the United Kingdom, Australia and Ireland) were identified and qualitatively analysed in detail to ascertain their potential to form ‘nodes of persisting complexity’ (New Zealand is identified as having the greatest potential). The analysis outputs are applied to identify insights for enhancing resilience to ‘de-complexification’.
Linking Food and Resource Access to Medical Care Access in Maputo, Mozambique
Authors: McCordic Cameron , Frayne Bruce , Sunu Naomi
Published: July 2021

Background: Rapid urbanization coupled with evolving threats from both communicable and non-communicable diseases underscore the vulnerability of urban healthcare systems. Building resilient healthcare systems and increasing access to socioeconomic resources is key for achieving sustainable development goals (SDGs). The city of Maputo (Mozambique) provides a helpful case study for the analysis of this situation. Methods: This investigation analyzes household survey data to determine the predictors of consistent household medical care access (SDG 3) in Maputo. Using those identified predictors, the study identifies key segments of households in Maputo that are vulnerable to disease given their inconsistent access to medical care. Results: The results indicate that households with inconsistent medical care access (SDG 3) also suffer from severe food insecurity (SDG 2) and inconsistent access to a cash income (SDG 8), water (SDG 6), and electricity (SDG 7). Conclusions: This study identifies challenges to the achievement of SDG 3 in Maputo, where households that are likely to need medical care under the strain of impoverished living conditions are also the least likely to have consistent access to needed medical care.
EU Policies Driving Entrepreneurial Competences—Reflections from the Case of EntreComp
Authors: Seikkula-Leino Jaana , Salomaa Maria , Jónsdóttir Svanborg Rannveig , McCallum Elin , Israel Hazel
Published: July 2021

The United Nations’ Sustainable Development Goals promote entrepreneurial competences as a means of supporting young people to innovate, start businesses, and create jobs. Furthermore, the European Union considers entrepreneurial skills to be essential in creating welfare and economic sustainability. Empowering individuals with entrepreneurship education, an entrepreneurial mindset and behaviors, are tools to develop human capital. This article explores how European policies can drive development of entrepreneurial competences by examining the case of the European Framework for Entrepreneurial Competences (EntreComp) and its integration into education and training development in different countries. With this research, we contribute education development from the practical point of view by analyzing how a cross section of actors, using EntreComp as a European framework for entrepreneurial competences, see that entrepreneurial learning has been realized and could be further supported in transnational education contexts. We will also expand the theoretical discussion of entrepreneurship education from the perspective of education sciences, as we have not previously obtained clarifying results or conclusions on how, for example, the educational change related to the development of entrepreneurship education should be implemented. The research data was collected through a case study, for which an online survey including both quantitative and qualitative approaches was conducted in 2020. Responses from 348 respondents from 47 countries were analyzed through an extended model for learning originally conceptualized by Shulman and Shulman (2004). The findings suggest that EntreComp has been widely recognized as a critical driver of competence in entrepreneurial education. However, a lack of shared vision and development of practice in the use of EntreComp can hinder the effective implementation of the framework. Thus, further support and guidance are needed in promoting the learning process of policymakers, educators, trainers, and other stakeholders, on both micro- and macro-level education design, to support successful adoption and adaptation of the policy-driven frameworks.
200 Years of Feminisation of Professions in Poland—Mechanism of False Windows of Opportunity
Authors: Świgost-Kapocsi Agnieszka
Published: July 2021

This paper presents the problem of the female labour market in Poland and the phenomenon of the feminisation of selected occupations. The main aim was to identify the mechanisms behind the feminisation of occupations in Poland and its consequences by combining considerations of labour market theory with development path theories. This research employed various methods such as the method of analysis of secular trends, as well as a critical reinterpretation of the literature review. Data from the 19th century to 2019 were analysed. The textile industry, education, local public administration, and social care are included in the analysis. The research motivation was to answer the question as to when and under what conditions the selected occupations were feminised. The mechanism of false windows of opportunity was identified, as well as times when the windows of opportunity to enter a given occupation opened and closed for women. Specifically, the research findings described that the female labour market is dependent on the male labour market and thus windows of opportunity offer new employment opportunities but with limited possibilities and under poorer conditions.
Sustaining University English as a Foreign Language Learners’ Writing Performance through Provision of Comprehensive Written Corrective Feedback
Authors: Cheng Xiaolong , Zhang Lawrence Jun
Published: July 2021

Writing is regarded as a crucial skill in English language curricula at the secondary and tertiary levels in the Chinese education system. Currently, Chinese teachers of English as a foreign language (EFL) often adopt a product approach to teaching EFL writing, in which they emphasize the quality of their students’ written products and show little concern with the writing process. To help L2 learners achieve sustainable development of their writing proficiency, teachers employ a comprehensive approach to correct their students’ language errors as a common practice. However, empirical studies regarding its efficacy on different dimensions of L2 writing are insufficient. This study intended to fill this lacuna in a Chinese EFL context, which investigated the effects of sustained comprehensive written corrective feedback (WCF) on accuracy, complexity, fluency, and content and organization quality of EFL students’ writing. Quasi-experimental in design, it involved a comparison group and a treatment group receiving four sessions of direct comprehensive WCF. Results show that such WCF contributed to writing accuracy and fluency over time. Our textual analysis further reveals that it particularly benefited students’ grammatical accuracy, reducing some rule-based grammatical error types. However, it showed limited effects on complexity, content, or organization of students’ writing. Interestingly, the comparison group did not improve any dimensions of their writing. Possible implications are also discussed.
Factors Influencing Corporate Social Responsibility Disclosure and Its Impact on Financial Performance: The Case of Vietnam
Authors: Nguyen Thanh Hung , Vu Quang Trong , Nguyen Duc Minh , Le Hoang Long
Published: July 2021

The study examines the impact of company size, industry sensitivity, government ownership, liquidity and company age on Corporate Social Responsibility Disclosure (CSRD) in 2019 annual reports of listed companies on the Vietnam stock market. We also consider the relationship between CSRD and the financial performance measured by return on assets (ROA) and return on equity (ROE). This study uses descriptive statistics and regression methods to test research hypotheses. The empirical findings show that company characteristics, including firm size, liquidity, government ownership and environmental industry sensitivity, are positively associated with firms’ CSRD level. Firm age does not influence the CSRD of listed companies. The CSRD significantly affects both ROA and ROE. Our study provides several suggestions to promote the CSR information disclosure of listed companies and enhance their social responsibility for sustainable development.
D-distance Risk Factor for Transmission Line Maintenance Management and Cost Analysis
Authors: Luejai Waraporn , Suwanasri Thanapong , Suwanasri Cattareeya
Published: July 2021

In this paper, a D-distance risk factor was proposed to prioritize high-voltage transmission lines from high to low risk in transmission line maintenance and renovation management. Various conditions and importance assessment criteria together with the weighting and scoring method were proposed to calculate both the renovation and importance indices of transmission lines. The scores of different test methods and visual inspection were differentiated from zero to five as end-of-life to very good condition to evaluate the condition of the line and its components. Additionally, the scores of different importance criteria were modified to assess the line importance from low to high importance. Moreover, the analytic hierarchy process was applied to determine the important weight of all test methods and importance criteria, which were evaluated by utility experts. The renovation and importance indices were combined in a risk matrix to finally determine the risk of the line by using the D-distance technique. Later, the risk of every transmission line was plotted in a risk matrix to prioritize and manage maintenance tasks. Finally, a maintenance cost was analyzed by applying the D-distance risk factor and compared with the replacement cost of a new transmission line for maintenance planning and cost minimization. Twenty out of 115, 230 and 500 kV transmission lines fleet in Thailand were practically analyzed with actual data. The results were realistic to feasibly implement in a transmission system for sustainable management.
The Critical Importance of Adopting Whole-of-Life Strategies for Polymers and Plastics
Authors: Moad Graeme , Solomon David Henry
Published: July 2021

Plastics have been revolutionary in numerous sectors, and many of the positive attributes of modern life can be attributed to their use. However, plastics are often treated only as disposable commodities, which has led to the ever-increasing accumulation of plastic and plastic by-products in the environment as waste, and an unacceptable growth of microplastic and nanoplastic pollution. The catchphrase “plastics are everywhere”, perhaps once seen as extolling the virtues of plastics, is now seen by most as a potential or actual threat. Scientists are confronting this environmental crisis, both by developing recycling methods to deal with the legacy of plastic waste, and by highlighting the need to develop and implement effective whole-of-life strategies in the future use of plastic materials. The importance and topicality of this subject are evidenced by the dramatic increase in the use of terms such as “whole of life”, “life-cycle assessment”, “circular economy” and “sustainable polymers” in the scientific and broader literature. Effective solutions, however, are still to be forthcoming. In this review, we assess the potential for implementing whole-of-life strategies for plastics to achieve our vision of a circular economy. In this context, we consider the ways in which given plastics might be recycled into the same plastic for potential use in the same application, with minimal material loss, the lowest energy cost, and the least potential for polluting the environment.
Information System Purchase and Integration Contingencies When Companies Merge
Authors: Engelseth Per , Sadowski Adam , Janusz Artur , Awaleh Fahad
Published: July 2021

This study grounds empirically the purchasing and further integration of an implemented information system set in the frenzied context of a corporate merger. A single longitudinal case study from the Norwegian pelagic seafood industry provides a detailed long-term account of developing the information system prior to, during and after a merger in the seafood industry that relies on wild catch. It is characterised by high dependence on features of nature and society to secure sustainable production. Contingency theory together with a process view of production reveals how interactions unfold over time to develop the new unified information system. Features of integration, interaction and interdependency represent different facets of information system purchase and development. The merger process represents an abnormality for the organisation as a continuous entity. Information system development in the case, therefore, takes place in a weakly integrated network of merging firms with severe time constraints. Given high uncertainty, solutions emerge through interaction. Deterministic optimisation is, in this context, a fluffy managerial dream. Normally, information system purchase and information system development involve reciprocal interdependencies involving mutual adjustments through intensive technologies and tight interaction among all parties involved. The coercive behaviour of management seeking efficiencies overrules these planning ideals. This indicates that purchasing, in a corporate merger context, is complex and approached as a complex system in a network. Solutions used in this approach originate because of emergent-networked interaction.
Gemini Principles-Based Digital Twin Maturity Model for Asset Management
Authors: Chen Long , Xie Xiang , Lu Qiuchen , Parlikad Ajith Kumar , Pitt Michael , Yang Jian
Published: July 2021

Various maturity models have been developed for understanding the diffusion and implementation of new technologies/approaches. However, we find that existing maturity models fail to understand the implementation of emerging digital twin technique comprehensively and quantitatively. This research aims to develop an innovative maturity model for measuring digital twin maturity for asset management. This model is established based on Gemini Principles to form a systematic view of digital twin development and implementation. Within this maturity model, three main dimensions consisting of nine sub-dimensions have been defined firstly, which were further articulated by 27 rubrics. Then, a questionnaire survey with 40 experts involved is designed and conducted to examine these rubrics. This model is finally illustrated and validated by two case studies in Shanghai and Cambridge. The results show that the digital twin maturity model is effective to qualitatively evaluate and compare the maturity of digital twin implementation at the project level. It can also initiate the roadmap for improving the performance of digital twin supported asset management.
Techno-Economic Assessment of Battery Electric Trains and Recharging Infrastructure Alternatives Integrating Adjacent Renewable Energy Sources
Authors: Streuling Christoph , Pagenkopf Johannes , Schenker Moritz , Lakeit Kim
Published: July 2021

Battery electric multiple units (BEMU) are an effective path towards a decarbonized regional rail transport on partly electrified rail lines. As a means of sector coupling, the BEMU recharging energy demand provided through overhead line islands can be covered from decentralized renewable energy sources (RES). Thus, fully carbon-free electricity for rail transport purposes can be obtained. In this study, we analyze cost reduction potentials of efficient recharging infrastructure positioning and the feasibility of covering BEMU energy demand by direct-use of locally produced renewable electricity. Therefore, we set up a model-based approach which assesses relevant lifecycle costs (LCC) of different trackside electrification alternatives comparing energy supply from local RES and grid consumption. The model-based approach is applied to the example of a German regional rail line. In the case of an overhead line island, the direct-use of electricity from adjacent wind power plants with on-site battery storage results in relevant LCC of EUR 173.4 M/30a, while grid consumption results in EUR 176.2 M/30a whereas full electrification results in EUR 224.5 M/30a. Depending on site-specific factors such as existing electrification and line lengths, BEMU operation and partial overhead line extension can lead to significant cost reductions of recharging infrastructure as compared to full electrification.
Wellness Tourism—New Challenges and Opportunities for Tourism in Salou
Authors: Andreu Marta Gemma Nel-lo , Font-Barnet Alba , Roca Marc Espasa
Published: July 2021

Following a long history of using various strategies and policies for diversification and seasonal adjustment in the face of the challenges of achieving economic, social, and environmental sustainability, sun and beach destinations should also consider targeting the wellness tourism market as a post pandemic opportunity and long-term solution. Salou is a mature sun and beach destination in the Mediterranean, but one which, for some time, has had an increasing commitment to family and sports tourism as a result of a strategic renewal process. Now, with the impact of the coronavirus pandemic, the destination management organization is considering the evolution of the model, the internalization of sustainability as a fundamental value, and the impact of different markets. In this study, we examined the challenges the Salou Tourist Board has faced during the development of a post pandemic model for sustainable tourism and what strategies it has adopted in response. We also considered the opportunities and competitive advantages that Salou has in the field of wellness tourism. The results obtained should encourage the continuation of work that promotes the environmental axis of sustainability and adds value to the natural resources on which it depends, including the sea and the landscape, while maintaining the environmental quality of the resources.
Beyond Cultural and Historic Values, Sustainability as a New Kind of Value for Historic Buildings
Authors: Onecha Belén , Dotor Alicia , Marmolejo-Duarte Carlos
Published: July 2021

In attempts to improve the energy efficiency of protected historical buildings, two barriers arise. The first is the restrictions imposed by authorities that are responsible for cultural heritage preservation. The second is the exclusion of protected buildings from strict compliance with energy efficiency requirements in current regulations, such as the issue of an Energy Performance Certificate, which removes them from conventional channels of public policies. Both of these issues put heritage in a delicate situation, especially when they are intended for privately developed residential uses. This paper presents a methodology for assessing and establishing a trade-off between energy performance and the cultural value of heritage buildings through the comprehensive analysis of a case study: the retrofitting of Can Armengol Palace in Palma de Mallorca (Spain). The study revealed (1) the need to objectify the cultural values of the building as far as possible to identify conflicts with the strategies of energy efficiency improvement; and (2) the appropriateness of considering every aspect of a rehabilitation intervention in a global simultaneous approach, not just energy aspects. The method that was used had five steps: acquiring a deep knowledge of the building configuration, assessing the building performance for every legal requirement, identifying cultural values, defining intervention criteria, and analyzing intervention effects on the protected elements of the building. The most important contribution in this study is the detailed and extended definition of architectural heritage values and the consideration of interventions resulting from sustainability retrofits as a new kind of value, that reflects current worries, for which future generations will remember us.
Effects of the Feeding Rate on Growth Performance, Body Composition, and Hematological Properties of Juvenile Mandarin Fish Siniperca scherzeri in a Recirculating Aquaculture System
Authors: Kim Yi-Oh , Oh Sung-Yong , Kim Taewon
Published: July 2021

The effects of feeding rate (0.5%, 1.0%, 1.5%, 2.0%, 2.5%, and 3.0% body weight [BW] per day [BW day−1]) on the growth, body composition, and blood properties of juvenile mandarin fish, Siniperca scherzeri, (initial BW 18.4 ± 0.2 g) were investigated in a water recirculating aquaculture system. Triplicate groups of fish were fed an experimental diet (55.4% protein, 14.1% lipid) for 10 weeks. Weight gain and specific growth rate increased with increasing feeding rates of up to 2.5% BW day−1, after which no significant increase in growth was observed. Feed efficiency, protein efficiency ratio, and protein retention were not significantly different among the fish fed 1–2.5% BW day−1 but decreased significantly in those fed 3.0% BW day−1. The lipid content of fish fed 2.5% BW day−1 was significantly higher than that at 0.5–1.5% BW day−1. The total plasma cholesterol content was significantly lower in fish fed 0.5 BW day−1 than fish provided with other feeding rates. Based on the growth, feed efficiency, body composition, and blood content analyses, including regression analysis, the optimal feeding rate for juvenile S. scherzeri weighing between 18 g and 54 g was estimated at 1.88–2.80% BW day−1 depending on weight gain, specific growth rate, and feed efficiency under 26.9 °C conditions.
COVID-19 Vaccination: What Do We Expect for the Future? A Systematic Literature Review of Social Science Publications in the First Year of the Pandemic (2020–2021)
Authors: Pratici Lorenzo , Singer Phillip McMinn
Published: July 2021

The Covid-19 pandemic has had wide-reaching societal and economic effects and a return to “normal” will take years to accomplish. In light of this situation, the most important advancement since COVID-19′s emergence has been the development of multiple, life-saving, vaccines. Academic research on vaccine has been extensive. It is estimated that in only one year it has been produced more published and indexed papers on this single issue than in the last twenty years on any other single issue, thus, necessitating some organization. This research consists of a systematic literature review of the social science publication on COVID-19 published in the first year of the pandemic (February 2020 to March 2021). This review is important because it occurs at a time when vaccines have begun their global distribution and the best efforts to address the pandemic is through vaccination programs. In this research, 53 papers published in relevant journals are analyzed out of the almost 30,000 articles retrieved from Scopus database. The analysis conducted relies on two different types: descriptive analysis (evolution at the time of citations; evolution over time of keywords; bibliographical mapping of countries, the top 10 most influential papers), and bibliometric analysis for content evaluation. A cluster analysis was performed for the latter. Clustering the research papers, based on the actual content of papers, found there to be five research areas: (1) economic aspects; (2) ethics and legal aspects; (3) health communication; (4) policies and crisis management, and (5) political issues. Yet, this article’s results paint a picture of literature that has not yet considered the full scope of COVID-19’s effect on the economic, political, and population level health and well-being. Nor has it considered these effects across the global community, suggesting new potential areas of research and giving a perspective of what we should expect for the future.
Local Structure and Dynamics of Functional Materials Studied by X-ray Absorption Fine Structure
Authors: Miyanaga Takafumi
Published: July 2021

X-ray absorption fine structure (XAFS) is a powerful technique used to analyze a local electronic structure, local atomic structure, and structural dynamics. In this review, I present examples of XAFS that apply to the local structure and dynamics of functional materials: (1) structure phase transition in perovskite PbTiO3 and magnetic FeRhPd alloys; (2) nano-scaled fluctuations related to their magnetic properties in Ni–Mn alloys and Fe/Cr thin films; and (3) the Debye–Waller factors related to the chemical reactivity for catalysis in polyanions and ligand exchange reaction. This study shows that the local structure and dynamics are related to the characteristic function of the materials.
Quadruple Roman Domination in Trees
Authors: Kou Zheng , Kosari Saeed , Hao Guoliang , Amjadi Jafar , Khalili Nesa
Published: July 2021

This paper is devoted to the study of the quadruple Roman domination in trees, and it is a contribution to the Special Issue “Theoretical computer science and discrete mathematics” of Symmetry. For any positive integer k, a [k]-Roman dominating function ([k]-RDF) of a simple graph G is a function from the vertex set V of G to the set {0,1,2,…,k+1} if for any vertex u∈V with f(u)<k, ∑x∈N(u)∪{u}f(x)≥|{x∈N(u):f(x)≥1}|+k, where N(u) is the open neighborhood of u. The weight of a [k]-RDF is the value Σv∈Vf(v). The minimum weight of a [k]-RDF is called the [k]-Roman domination number γ[kR](G) of G. In this paper, we establish sharp upper and lower bounds on γ[4R](T) for nontrivial trees T and characterize extremal trees.
Refinements of Wilker–Huygens-Type Inequalities via Trigonometric Series
Authors: Bercu Gabriel
Published: July 2021

The study of even functions is important from the symmetry theory point of view because their graphs are symmetrical to the Oy axis; therefore, it is essential to analyse the properties of even functions for x greater than 0. Since the functions involved in Wilker–Huygens-type inequalities are even, in our approach, we use cosine polynomials expansion method in order to provide new refinements of the above-mentioned inequalities.
On New Formulas of Fibonacci and Lucas Numbers Involving Golden Ratio Associated with Atomic Structure in Chemistry
Authors: Battaloglu Rifat , Simsek Yilmaz
Published: July 2021

The main purpose of this paper is to give many new formulas involving the Fibonacci numbers, the golden ratio, the Lucas numbers, and other special numbers. By using generating functions for the special numbers with their functional equations method, we also give many new relations among the Fibonacci numbers, the Lucas numbers, the golden ratio, the Stirling numbers, and other special numbers. Moreover, some applications of the Fibonacci numbers and the golden ratio in chemistry are given.
Rutin-Functionalized Multi-Walled Carbon Nanotubes: Molecular Docking, Physicochemistry and Cytotoxicity in Fibroblasts
Authors: Neto Conrado , Lima Felipe , Morais Renata , de Andrade Lucas , de Lima Renata , Chaud Marco , Pereira Matheus , de Albuquerque Júnior Ricardo , Cardoso Juliana , Zielińska Aleksandra , Souto Eliana , Lima Álvaro , Severino Patrícia
Published: July 2021

Multi-Walled Carbon Nanotubes (MWCNT) have been functionalized with rutin through three steps (i. reaction step; ii. purification step; iii. drying step) and their physicochemical properties investigated with respect to morphological structure, thermal analysis, Fourier Transform Infrared Spectroscopy (FTIR), and cytotoxicity. The molecular docking suggested the rutin-functionalized MWCNT occurred by hydrogen bonds, which was confirmed by FTIR assays, corroborating the results obtained by thermal analyses. A tubular shape, arranged in a three-dimensional structure, could be observed. Mild cytotoxicity observed in 3T3 fibroblasts suggested a dose–effect relationship after exposure. These findings suggest the formation of aggregates of filamentous structures on the cells favoring the cell penetration.