• 2008–2017 Bogota River Water Quality Assessment based on the Water Quality Index

      Daissy Milena Díaz-Casallas; Mario Fernando Castro-Fernández; Elvira Bocos; Carlos Enrique Montenegro-Marin; Rubén González Crespo (MDPI AG, 2019-03-01)
      This article provides a deep analysis of the water quality at the upper basin of the Bogota River (Colombia) between 2008 and 2017. The Water Quality Index has been the indicator employed to determine the ecological status of the river. This index was chosen in order to normalize the analysis, given that it is commonly used by the Institute of Hydrology, Meteorology and Environmental Studies, a government agency of the Ministry of Environment and Sustainable Development of Colombia, to determine the state of surface effluents. The results obtained were organized in a double-entry matrix in order to relate the variables of the sample period and the sampling station. The research revealed an insufficient quality of water, demonstrating that the high stretch of the Bogota River basin has, in general, regular or acceptable water quality, while only five stations showed an acceptable status. Surprisingly, the stations located close to the wastewater treatment plants of the municipalities of Choconta, Suesca, Gachancipa, and Tocancipa, as well as Rio Negro, have a poor water quality, discharging a high load of contaminants into the river. Although great efforts have been made by Colombian authorities to restore the critical state of the majority of their aquatic ecosystems, recent implementation of policies and instruments have not shown significant achievements yet. For this reason, this study aims to present a powerful decision-tool for the monitoring and evaluation of correction measures implemented on this river basin. The data used in this research were provided by the Regional Autonomous Corporation of Cundinamarca.
    • 2050 Scenarios for Long-Haul Tourism in the Evolving Global Climate Change Regime

      Jako Volschenk; Marius Ungerer; Shaun Vorster (MDPI AG, 2012-12-01)
      Tourism and its “midwife”, aviation, are transnational sectors exposed to global uncertainties. This scenario-building exercise considers a specific subset of these uncertainties, namely the impact of the evolving global climate change regime on long-haul tourism (LHT), with a 2050 horizon. The basic problematique is that unconstrained growth in aviation emissions will not be compatible with 2050 climate stabilisation goals, and that the stringency and timing of public policy interventions could have far-reaching impacts — either on the market for future growth of LHT, or the natural ecosystem on which tourism depends. Following an intuitive-logic approach to scenario-building, three meta-level scenarios that can be regarded as “possible” futures for the evolution of LHT are described. Two of these, i.e., the “grim reaper” and the “fallen angel” scenarios, are undesirable. The “green lantern” scenario represents the desired future. Long-haul tourist destinations should heed the early warning signals identified in the scenario narratives, and contribute towards realising the desired future. They should further guard against being passive victims if the feared scenarios materialise, by adapting, repositioning early upon reading the signposts, hedging against risks, and seizing new opportunities.
    • 2052: A Global Forecast for the Next Forty Years. By Jorgen Randers, Chelsea Green Publishing, 2012; 304 pages. Price US$ 24.95 ISBN 978-1-60358-467-8

      Shu-Kun Lin (MDPI AG, 2012-10-01)
      Forty years ago, The Limits to Growth study addressed the grand question of how humans would adapt to the physical limitations of planet Earth. It predicted that during the first half of the 21st century the ongoing growth in the human ecological footprint would stop—either through catastrophic “overshoot and collapse”—or through well-managed “peak and decline.”
    • 2D Versus 3D: The Relevance of the Mode of Presentation for the Economic Valuation of an Alpine Landscape

      Michael Getzner; Barbara Färber; Claudia Yamu (MDPI AG, 2016-06-01)
      In order to value the transformation of landscapes from an economic perspective, survey respondents are usually presented with pictures of various landscapes with the aim to visualize differences in their appearance. The current paper presents a classroom experiment ascertaining differences, and potential advantages and disadvantages, of 2D versus 3D (stereoscopic) presentations of landscape changes. The landscape to be valued was a traditional Alpine pasture in the Austrian Alps as a prominent example of natural and cultural heritage (traditional economy and specific ecology). Two alternative scenarios included, on the one hand, changes in agricultural uses, leading to natural afforestation (reforestation) and decay of existing infrastructure (e.g., hiking trails). On the other hand, significantly extended tourism infrastructure (e.g., new attractions for visitors) was presented. Two groups were presented manipulated pictures (2D/non-stereoscopic), and 3D (stereoscopic) presentations with 3D glasses, respectively. Both groups were then asked for their perception of landscape changes. It turns out that significant differences between the two groups could be detected in terms of the frequency of vacations at Alpine pastures. For instance, respondents in the 3D stereoscopic group stated a significantly higher frequency of trips. However, on the other hand, they did not state a significantly different willingness-to-pay to prevent landscape changes disadvantageous in terms of sustainability. The study results thus suggest that the mode of presentation may affect the valuation of landscape changes depending on the valuation instrument.
    • 36th Cordoba Guitar Festival: Spectator Analysis Using Structural Equation Modelling (SEM)

      Juan V. Fruet-Cardozo; Jesús C. Pérez-Gálvez; Carol Jara-Alba; Gema Gómez-Casero (MDPI AG, 2019-02-01)
      The Cordoba Guitar Festival is one of the most important cultural events in Spain. This article analyses the musical preferences, satisfaction, attitudinal loyalty, and behavioural loyalty of spectators who attended the 36th festival held in July 2016, as well as the festival’s economic impact on the city. These characteristics of the public give rise to the four hypotheses of this study. To achieve this aim, a structural equation model (SEM) was used. The results −χ<sup>2</sup> = 27.79, with the <i>p</i>-value found to be <i>p</i> = P (χ<sup>2</sup> ≥ 27.79) = 0.224—show the goodness-of-fit of the model and indicate that the observed data do fit the expected dataset. The results therefore allow us to accept the proposed hypotheses concerning the influence of different latent factors, such as musical preferences, loyalty, and satisfaction with the festival. This is the main focus with which the present study has been written. Regarding the economic impact, the Festival raised 1.2 million euros, that is, slightly more than 73,000 euros per day. The amount, although not very high, is important as additional income for the city. The conclusions show the need to consider the preferences of the spectator as an essential tool to enable the continuation and longevity of the Cordoba Guitar Festival—an important cultural destination.
    • 3D Digital Heritage Models as Sustainable Scholarly Resources

      Erik Champion; Hafizur Rahaman (MDPI AG, 2019-04-01)
      If virtual heritage is the application of virtual reality to cultural heritage, then one might assume that virtual heritage (and 3D digital heritage in general) successfully communicates the need to preserve the cultural significance of physical artefacts and intangible heritage. However, digital heritage models are seldom seen outside of conference presentations, one-off museum exhibitions, or digital reconstructions used in films and television programs. To understand why, we surveyed 1483 digital heritage papers published in 14 recent proceedings. Only 264 explicitly mentioned 3D models and related assets; 19 contained links, but none of these links worked. This is clearly not sustainable, neither for scholarly activity nor as a way to engage the public in heritage preservation. To encourage more sustainable research practices, 3D models must be actively promoted as scholarly resources. In this paper, we also recommend ways researchers could better sustain these 3D models and assets both as digital cultural artefacts and as tools to help the public explore the vital but often overlooked relationship between built heritage and the natural world.
    • 3D Virtual Itinerary for Education Using Google Earth as a Tool for the Recovery of the Geological Heritage of Natural Areas: Application in the “Las Batuecas Valley” Nature Park (Salamanca, Spain)

      Antonio Miguel Martínez-Graña; José González-Delgado; Silvia Pallarés; José Luis Goy; Jorge Civis Llovera (MDPI AG, 2014-11-01)
      The objective of this study is to develop a methodology that enhances the value and position of the geological heritage of any natural area in the world using a 3D virtual itinerary. Field applications of this geological itinerary enable students to participate actively in teaching and learning theoretical concepts in the earth sciences and engineering. The educational resources, which include a virtual itinerary, a flight simulator, a field notebook with questionnaires, videos, and an augmented reality developed with Google Earth, provide a familiar and effective learning environment that can be implemented by students daily using new technologies (smartphones, tablets, and iPods) and can leverage the power of computer games to achieve the objectives of a specific curriculum. The implementation of geological content in an interactive, educational game has been employed in compulsory levels of secondary education, high school, and college in Batuecas Valley. The geomatic applications are free as they can be accessed from existing computer labs.
    • 3DPortCityMeasure: Methodology for the Comparative Study of Good Practices in Port–City Integration

      María J. Andrade; João Pedro Costa; José Blasco López (MDPI AG, 2020-01-01)
      Most port cities have a long history of investment in the waterfront, adapting these spaces to improve the quality of life of its inhabitants and increase the tourist interest of the city, in a 50-year process of waterfront regeneration that started in the late 1960s. Even though one of the drivers of development in today’s port cities continues to be the transfer of knowledge and experiences between different cases, not all these cities have achieved their goals, nor have all done so in a sustainable way. This article exposes a new methodology, motivated by the need to carry out a comparative study of good practices of port−city integration for twelve specific cases. To enable a comparison of intangible realities such as port−city integration, it is mandatory to have a common benchmark to quantify features of cities from different cases. The 3DPortCityMeasure methodology is intended to provide a framework for analysing port-city integration, with results that supply an immediate understanding of each case. This tool enables direct comparative evaluation and provides support for land use planning and urban design approaches. The results show that the proposed approach for measuring intangible factors in the field of the port−city relationship is a very useful tool, novel in this discipline, and fully applicable to other cases and other urban issues.
    • 5 Key Challenges and Solutions for Governing Complex Adaptive (Food) Systems

      Mollie Chapman; Susanna Klassen; Maayan Kreitzman; Adrian Semmelink; Kelly Sharp; Gerald Singh; Kai M. A. Chan (MDPI AG, 2017-09-01)
      There is increasing recognition in academic circles of the importance of adaptive governance for the sustainability of social-ecological systems, but little examination of specific implications for the 34% of land-use where human activities are pervasive but potentially commensurate with functioning ecosystems: agricultural production systems. In this paper, we argue for the need to view food systems and agro-ecosystems as multi-scalar complex adaptive systems and identify five key challenging characteristics of such systems: multi-causality; cumulative impacts; regime shifts; teleconnections and mismatch of scales. These characteristics are necessary features of multi-scalar adaptive systems, and apply equally to social and natural subsystems. We discuss the implications of these characteristics for agricultural production systems and consider how governance can rise to these challenges. We present five case studies that highlight these issues: pollinator declines; payments for ecosystem services; pest control and pesticide resistance; downstream aquatic systems in Tasman Bay, New Zealand; and riparian buffers in Puget Sound, USA. From these case studies we derive recommendations for managing agricultural systems, both specific and general. Ultimately, adaptive governance of agro-ecosystems will likely hinge upon three paradigm shifts: viewing farmers and ranchers not only as food producers but also as land and water managers; seeking not yield maximization but rather resilient management of food ecosystems; and critically, as it transcends the production-system literature, engaging broad audiences not only as consumers but also citizens.
    • 5G Mobile Services and Scenarios: Challenges and Solutions

      Yousaf Bin Zikria; Sung Won Kim; Muhammad Khalil Afzal; Haoxiang Wang; Mubashir Husain Rehmani (MDPI AG, 2018-10-01)
      The Fifth generation (5G) network is projected to support large amount of data traffic and massive number of wireless connections. Different data traffic has different Quality of Service (QoS) requirements. 5G mobile network aims to address the limitations of previous cellular standards (i.e., 2G/3G/4G) and be a prospective key enabler for future Internet of Things (IoT). 5G networks support a wide range of applications such as smart home, autonomous driving, drone operations, health and mission critical applications, Industrial IoT (IIoT), and entertainment and multimedia. Based on end users’ experience, several 5G services are categorized into immersive 5G services, intelligent 5G services, omnipresent 5G services, autonomous 5G services, and public 5G services. In this paper, we present a brief overview of 5G technical scenarios. We then provide a brief overview of accepted papers in our Special Issue on 5G mobile services and scenarios. Finally, we conclude this paper.
    • 90 Days of COVID-19 Social Distancing and Its Impacts on Air Quality and Health in Sao Paulo, Brazil

      Daniela Debone; Mariana V. da Costa; Simone G. E. K. Miraglia (MDPI AG, 2020-09-01)
      The COVID-19 pandemic has imposed a unique situation for humanity, reaching up to 5623 deaths in Sao Paulo city during the analyzed period of this study. Due to the measures for social distancing, an improvement of air quality was observed worldwide. In view of this scenario, we investigated the air quality improvement related to PM<sub>10</sub>, PM<sub>2.5</sub>, and NO<sub>2</sub> concentrations during 90 days of quarantine compared to an equivalent period in 2019. We found a significant drop in air pollution of 45% of PM<sub>10</sub>, 46% of PM<sub>2.5</sub>, and 58% of NO<sub>2</sub>, and using a relative-risk function, we estimated that this significant air quality improvement avoided, respectively, 78, 337, and 387 premature deaths, respectively, and prevented approximately US$ 720 million on health costs. Moreover, we estimated that 5,623 deaths by COVID-19 represent an economic health loss of US$ 10.5 billion. Both health and economic gains associated with air pollution reductions give a positive perspective of the efforts towards keeping air pollution reduced even after the pandemic, highlighting the importance of improving the strategies of air pollution mitigation actions, as well as the crucial role of adopting efficient measures to protect human health both during and after the COVID-19 global health crisis.
    • A <i>p</i>-Robust Green Supply Chain Network Design Model under Uncertain Carbon Price and Demand

      Ruozhen Qiu; Shunpeng Shi; Yue Sun (MDPI AG, 2019-10-01)
      The problem of designing a multi-product, multi-period green supply chain network under uncertainties in carbon price and customer demand is studied in this paper. The purpose of this study is to develop a robust green supply chain network design model to minimize the total cost and to effectively cope with uncertainties. A scenario tree method is applied to model the uncertainty, and a green supply chain network design model is developed under the <i>p</i>-robustness criterion. Furthermore, the solution method for determining the lower and upper bounds of the relative regret limit is introduced, which is convenient for decision-makers to choose the corresponding supply chain network structure through the tradeoff between risk and cost performance. In particular, to overcome the large scale of the model caused by a high number of uncertain scenarios and reduce the computational difficulty, a scenario reduction technique is applied to filter the scenarios. Numerical calculations are executed to analyze the influence of relevant parameters on the performance of the designed green supply chain network. The results show that the proposed <i>p</i>-robust green supply chain network design model can effectively deal with carbon and demand uncertainties while ensuring cost performance, and can offer more choices for decision-makers with different risk preferences.
    • A 10-Year Statistical Analysis of Heavy Metals in River and Sediment in Hengyang Segment, Xiangjiang River Basin, China

      Jingwen Tang; Liyuan Chai; Huan Li; Zhihui Yang; Weichun Yang (MDPI AG, 2018-04-01)
      Heavy metal elements in water and surface sediments were characterized in Hengyang river segment in Xiangjiang River basin, one of China’s most important heavy metal control and treatment region. Data of heavy metal monitoring results in water and sediment for 10 years were acquired from an environmental monitoring program in the main channel of the studied area. Descriptive and exploratory statistical procedures were performed to reveal the characteristics of the sample distributions of heavy metal elements. The sample distributions of heavy metal elements were largely skewed right. Data censoring and too severe rounding in the water monitoring data were identified to have caused discretization in the sample distributions. Temporal and spatial characteristics of the data sets were addressed. The chromium (Cr) in the sediment possessed unique behavior, and this could be caused by a rapid deposition and releasing process.
    • A Balancing Method of Mixed-model Disassembly Line in Random Working Environment

      Xuhui Xia; Wei Liu; Zelin Zhang; Lei Wang; Jianhua Cao; Xiang Liu (MDPI AG, 2019-04-01)
      Disassembly is a necessary link in reverse supply chain and plays a significant role in green manufacturing and sustainable development. However, the mixed-model disassembly of multiple types of retired mechanical products is hard to be implemented by random influence factors such as service time of retired products, degree of wear and tear, proficiency level of workers and structural differences between products in the actual production process. Therefore, this paper presented a balancing method of mixed-model disassembly line in a random working environment. The random influence of structure similarity of multiple products on the disassembly line balance was considered and the workstation number, load balancing index, prior disassembly of high demand parts and cost minimization of invalid operations were taken as targets for the balancing model establishment of the mixed-model disassembly line. An improved algorithm, adaptive simulated annealing genetic algorithm (ASAGA), was adopted to solve the balancing model and the local and global optimization ability were enhanced obviously. Finally, we took the mixed-model disassembly of multi-engine products as an example and verified the practicability and effectiveness of the proposed model and algorithm through comparison with genetic algorithm (GA) and simulated annealing algorithm (SA).
    • A Bamboo Treatment Procedure: Effects on the Durability and Mechanical Performance

      Quoc-Bao Bui; Anne-Cécile Grillet; Hoang-Duy Tran (MDPI AG, 2017-08-01)
      Bamboo is a natural material having a fast reproduction and high mechanical strengths. However, when a bio-based material in general, and bamboo in particular are expected to be a construction material, their sensitivity to moisture and their durability are usually questionable. Indeed, it is well known that these materials do not possess the same performance in the long-term, when compared to industrial materials. Sustainable solutions for the bamboo treatment still need to be investigated. The present study explores the oil-heated treatment with different types of oils, like flax or sunflower oils. The present investigation concentrates on mechanical properties and durability of treated bamboos to assess the effectiveness of these kinds of treatment. First, bamboo specimens were treated to decrease their sensitivity to moisture and improve their durability. Different conditions of treatment were tested: treatment at 100 °C or 180 °C; with flax oil, sunflower oil, or without oil; treatment durations of 1 h, 2 h, or 3 h; and, different cooling methods and cooling durations. Then, mechanical and durability tests were carried out on untreated and treated bamboos: uniaxial compression tests, 3 points bending tests, water immersion tests, and humidity tests. The results showed that some tested treatment methods could increase both the durability and the compressive strength of treated specimens, compared to untreated bamboo. The best results were observed on specimens treated at 180 °C during 1 h or 2 h without oil, and then cooled in 20 °C sunflower oil.
    • A Basic Study on a Rectangular Plane Space Sound Absorber Using Permeable Membranes

      Kimihiro Sakagami; Takeshi Okuzono; Yu Somatomo; Kota Funahashi; Masahiro Toyoda (MDPI AG, 2019-04-01)
      In this communication, the sound absorption characteristics of rectangular-shaped plane space sound absorbers without any backing structure using permeable membranes (PMs) are measured by reverberation room method. First, three types of PMs, in this study woven fabrics, are selected with different flow resistances and surface densities. They are prepared in the plane rectangular-shaped space absorbers of two different sizes. The measured results are discussed through comparison with the existing theoretical and measured results for absorbers of the other shapes or configurations. The present results and discussion demonstrate that the reverberation absorption coefficients of the proposed absorbers are low at low frequencies and converge to a moderately high value at high frequencies. Especially, ones with higher flow resistance than the air impedance converge to a value greater than 0.5, which is a theoretically estimated maximum absorption coefficient of infinite single-leaf PM. This is inferred to be attributed mainly to area effect. From these results the proposed absorbers can be used effectively despite of their very simple structure. Also it is found that the proposed absorber can offer higher sound absorption than permeable membrane absorbers of other shapes or configuration. Regarding the effect of the size, the absorbers of smaller size offer higher absorption coefficients regardless of material properties of the PMs used in the experiments.
    • A Bayesian Network-Based Integrated for Flood Risk Assessment (InFRA)

      Hongjun Joo; Changhyun Choi; Jungwook Kim; Deokhwan Kim; Soojun Kim; Hung Soo Kim (MDPI AG, 2019-07-01)
      Floods are natural disasters that should be considered a top priority in disaster management, and various methods have been developed to evaluate the risks. However, each method has different results and may confuse decision-makers in disaster management. In this study, a flood risk assessment method is proposed to integrate various methods to overcome these problems. Using factor analysis and principal component analysis (PCA), the leading indicators that affect flood damage were selected and weighted using three methods: the analytic hierarchy process (AHP), constant sum scale (CSS), and entropy. However, each method has flaws due to inconsistent weights. Therefore, a Bayesian network was used to present the integrated weights that reflect the characteristics of each method. Moreover, a relationship is proposed between the elements and the indicators based on the weights called the Integrated Index for Flood Risk Assessment (InFRA). InFRA and other assessment methods were compared by receiver operating characteristics (ROC)-area under curve (AUC) analysis. As a result, InFRA showed better applicability since InFRA was 0.67 and other methods were less than 0.5.
    • A Behavioral Model of Managerial Perspectives Regarding Technology Acceptance in Building Energy Management Systems

      Jacky Chin; Shu-Chiang Lin (MDPI AG, 2016-07-01)
      The Building Energy Management System (BEMS), a well-known system that has been implemented in some energy corporations, has become attractive to many companies seeking to better monitor their energy consumption efficiency. This study investigated the external factors that influence acceptance of the BEMS from managerial perspectives. An extended model based on the Technology Acceptance Model (TAM) was created to evaluate the implementation of the BEMS in the manufacturing industries. A structural equation modeling (SEM) approach was used to analyze the model by adopting compatibility, features, technology complexity, and perceived risk as the external variables, and integrating the five dimensions of perceived ease of use, perceived usefulness, attitude, user satisfaction, and behavioral intention. The analysis results indicated that the external factors positively influenced users’ behavioral intention to use the BEMS through expected satisfaction, perceived ease of use, and perceived usefulness. Suggestions for BEMS developers are provided as well.
    • A Benchmarking System for Domestic Water Use

      Dexter V. L. Hunt; Christopher D. F. Rogers (MDPI AG, 2014-05-01)
      The national demand for water in the UK is predicted to increase, exacerbated by a growing UK population, and home-grown demands for energy and food. When set against the context of overstretched existing supply sources vulnerable to droughts, particularly in increasingly dense city centres, the delicate balance of matching minimal demands with resource secure supplies becomes critical. When making changes to "internal" demands the role of technological efficiency and user behaviour cannot be ignored, yet existing benchmarking systems traditionally do not consider the latter. This paper investigates the practicalities of adopting a domestic benchmarking system (using a band rating) that allows individual users to assess their current water use performance against what is possible. The benchmarking system allows users to achieve higher benchmarks through any approach that reduces water consumption. The sensitivity of water use benchmarks are investigated by making changes to user behaviour and technology. The impact of adopting localised supplies (i.e., Rainwater harvesting—RWH and Grey water—GW) and including "external" gardening demands are investigated. This includes the impacts (in isolation and combination) of the following: occupancy rates (1 to 4); roof size (12.5 m2 to 100 m2); garden size (25 m2 to 100 m2) and geographical location (North West, Midlands and South East, UK) with yearly temporal effects (i.e., rainfall and temperature). Lessons learnt from analysis of the proposed benchmarking system are made throughout this paper, in particular its compatibility with the existing Code for Sustainable Homes (CSH) accreditation system. Conclusions are subsequently drawn for the robustness of the proposed system.
    • A Benefit–Cost Analysis of Food and Biodegradable Waste Treatment Alternatives: The Case of Oita City, Japan

      Micky A. Babalola (MDPI AG, 2020-03-01)
      As the generation of food scrap, kitchen, and biodegradable wastes increases, the proper handling of these wastes is becoming an increasingly significant concern for most cities in Japan. A substantial fraction of food and biodegradable waste (FBW) ends up in the incinerator. Therefore, an analytic hierarchy process (AHP) benefit−cost analysis technique was employed in this study to compare different FBW treatment technologies and select the most appropriate FBW disposal technology for Oita City. The four FBW treatment options considered were those recommended by the Japanese Food Waste Recycling Law: anaerobic digestion, compost, landfill, and incineration, which is currently in use. The fundamental AHP was separated into two hierarchy structures for benefit analysis and cost analysis. The criteria used in these two analyses were value added, safety, efficiency, and social benefits for benefit analysis, and cost of energy, cost of operation and maintenance, environmental constraints, and disamenity for cost analysis. The results showed that anaerobic digestion had the highest overall benefit while composting had the least cost overall. The benefit−cost ratio result showed that anaerobic digestion is the most suitable treatment alternative, followed by composting and incineration, with landfill being the least favored. The study recommends that composting could be combined with anaerobic digestion as an optimal FBW management option in Oita City.