bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of AM Parameters on Surface Roughness Obtained in PLA Parts Printed with FFF Technology
Authors: Buj-Corral Irene , Sánchez-Casas Xavier , Luis-Pérez Carmelo J.
Published: July 2021

Fused filament fabrication (FFF) 3D printing technology allows very complex parts to be obtained at a relatively low cost and in reduced manufacturing times. In the present work, the effect of main 3D printing parameters on roughness obtained in curved surfaces is addressed. Polylactic acid (PLA) hemispherical cups were printed with a shape similar to that of the acetabular part of the hip prostheses. Different experiments were performed according to a factorial design of experiments, with nozzle diameter, temperature, layer height, print speed and extrusion multiplier as variables. Different roughness parameters were measured—Ra, Rz, Rku, Rsk—both on the outer surface and on the inner surface of the parts. Arithmetical mean roughness value Ra and greatest height of the roughness profile Rz are usually employed to compare the surface finish among different manufacturing processes. However, they do not provide information about the shape of the roughness profile. For this purpose, in the present work kurtosis Rku and skewness Rsk were used. If the height distribution in a roughness profile follows a normal law, the Rku parameter will take a value of 3. If the profile distribution is symmetrical, the Rsk parameter will take a value of 0. Adaptive neural fuzzy inference system (ANFIS) models were obtained for each response. Such models are often employed to model different manufacturing processes, but their use has not yet been extended to 3D printing processes. All roughness parameters studied depended mainly on layer height, followed by nozzle diameter. In the present work, as a general trend, Rsk was close to but lower than 0, while Rku was slightly lower than 3. This corresponds to slightly higher valleys than peaks, with a rounded height distribution to some degree.
An Injectable Hybrid Gelatin Methacryloyl (GelMA)/Phenyl Isothiocyanate-Modified Gelatin (Gel-Phe) Bioadhesive for Oral/Dental Hemostasis Applications
Authors: Chang Wan-Chun , Tai Au-Zou , Tsai Nian-Yun , Li Yi-Chen Ethan
Published: July 2021

Biomaterials are widely used for effectively controlling bleeding in oral/dental surgical procedures. Here, gelatin methacryloyl (GelMA) was synthesized by grafting methacrylic anhydride on gelatin backbone, and phenyl isothiocyanate-modified gelatin (Gel-Phe) was synthesized by conjugating different gelatin/phenyl isothiocyanate molar ratios (G/P ratios) (i.e., 1:1, 1:5, 1:10, 1:15, 1:25, 1:50, 1:100, and 1:150) with gelatin polymer chains. Afterward, we combined GelMA and Gel-Phe as an injectable and photo-crosslinkable bioadhesive. This hybrid material system combines photo-crosslinking chemistry and supramolecular interactions for the design of bioadhesives exhibiting a highly porous structure, injectability, and regulable mechanical properties. By simply regulating the G/P ratio (1:1–1:15) and UV exposure times (15–60 s), it was possible to modulate the injectability and mechanical properties of the GelMA/Gel-Phe bioadhesive. Moreover, we demonstrated that the GelMA/Gel-Phe bioadhesive showed low cytotoxicity, a highly porous network, and the phenyl-isothiourea and amine residues on Gel-Phe and GelMA polymers with synergized hemostatic properties towards fast blood absorption and rapid clotting effect. An in vitro porcine skin bleeding and an in vitro dental bleeding model confirmed that the bioadhesive could be directly extruded into the bleeding site, rapidly photo-crosslinked, and reduced blood clotting time by 45%. Moreover, the in situ crosslinked bioadhesive could be easily removed from the bleeding site after clotting, avoiding secondary wound injury. Overall, this injectable GelMA/Gel-Phe bioadhesive stands as a promising hemostatic material in oral/dental surgical procedures.
Effect of Printing Parameters on the Tensile Properties of 3D-Printed Polylactic Acid (PLA) Based on Fused Deposition Modeling
Authors: Hsueh Ming-Hsien , Lai Chao-Jung , Chung Cheng-Feng , Wang Shi-Hao , Huang Wen-Chen , Pan Chieh-Yu , Zeng Yu-Shan , Hsieh Chia-Hsin
Published: July 2021

In order to optimize the efficiency of the Fused deposition modeling (FDM) process, this study used polylactic acid (PLA) material under different parameters (the printing angle and the raster angle) to fabricate specimens and to explore its tensile properties. The effect of the ultraviolet (UV) curing process on PLA materials was also investigated. The results showed that the printing and raster angles have a high impact on the tensile properties of PLA materials. The UV curing process enhanced the brittleness and reduced the elongation of PLA material. Different effects were observed on tensile strength and modulus of specimens printed with different parameters after UV curing. The above results will be a great help for researchers who are working to achieve sustainability of PLA materials and FDM technology.
Bi-Functional Catalyst/Sorbent for a H2-Rich Gas from Biomass Gasification
Authors: Micheli Francesca , Mattucci Enrica , Courson Claire , Gallucci Katia
Published: July 2021

The aim of this work is to identify the effect of the CaO phase as a CO2 sorbent and mayenite (Ca12Al14O33) as a stabilizing phase in a bi-functional material for CO2 capture in biomass syngas conditioning and cleaning at high temperature. The effect of different CaO weight contents is studied (0, 56, 85, 100 wt%) in sorbents synthesized by the wet mixing method. These high temperature solid sorbents are upgraded to bi-functional compounds by the addition of 3 or 6 wt% of nickel chosen as the metal active phase. N2 adsorption, X-ray diffraction, scanning electronic microscopy, temperature-programmed reduction analyses and CO2 sorption study were performed to characterize structural, textural, reducibility and sorption properties of bi-functional materials. Finally, sorption-enhanced reforming of toluene (chosen as tar model), of methane then of methane and toluene with bi-functional compounds were performed to study the best material to improve H2 content in a syngas, provided by steam biomass gasification. If the catalytic activity on the sorption enhanced reforming of methane exhibits a fast fall-down after 10–15 min of experimental test, the reforming of toluene reaches a constant conversion of 99.9% by using bi-functional materials.
Analytical Continuation within the Freundlich Adsorption Model. Comment on Edet, U.A.; Ifelebuegu, A.O. Kinetics, Isotherms, and Thermodynamic Modeling of the Adsorption of Phosphates from Model Wastewater Using Recycled Brick Waste. Processes 2020, 8, 665
Authors: Vigdorowitsch Michael , Pchelintsev Alexander N. , Tsygankova Liudmila E.
Published: July 2021

Using experimental data for the adsorption of phosphates out of wastewater on waste recycled bricks, published independently in MDPI Processes before (2020), this message re-visits the mathematical theory of the Freundlich adsorption model. It demonstrates how experimental data are to be deeper treated to model the saturation regime and to bridge a chasm between those areas where the data fit the Freundlich power function and where a saturation of surface adsorption centers occurs.
Hydrogen for Maritime Application—Quality of Hydrogen Generated Onboard Ship by Electrolysis of Purified Seawater
Authors: Bacquart Thomas , Moore Niamh , Wilmot Robbie , Bartlett Sam , Morris Abigail Siân Olivia , Olden James , Becker Hans , Aarhaug Thor Anders , Germe Sebastien , Riot Patrick , Murugan Arul , Mattelaer Vincent
Published: July 2021

Maritime transport is investigating several options to reduce its greenhouse gases and air pollutant emissions. An experimental ship, Energy Observer, is using excess renewable energy to generate onboard hydrogen by electrolysis of purified seawater. As a promising option for storing energy, it can provide on-demand energy to the ship through a hydrogen fuel cell (FC). As hydrogen FCs lifetime and performance are correlated to hydrogen quality, the hydrogen produced onboard needs to be monitored. This study assesses the probability of contaminants presence for this electrolyser, using purified seawater and supports the results with a hydrogen fuel quality analysis from the Energy Observer ship. It demonstrates that an electrolyser using onboard purified seawater can generate hydrogen of a quality compliant with ISO 14687:2019. Additional contaminants (i.e., ions, heavy metal) were also measured. The study highlights the potential contaminants to be monitored and future research on new contaminants from seawater to further develop hydrogen fuel for maritime applications.
Gas Migration in the Aspect of Safety in the Areas of Mines Selected for Closure
Authors: Chećko Jarosław , Howaniec Natalia , Paradowski Krzysztof , Smolinski Adam
Published: July 2021

One of the main hazards occurring in post-mining areas is the uncontrolled migration of gases to the surface, which may pose a serious threat to life and health. These gases are mainly methane and carbon dioxide, in smaller amounts ethane and higher hydrocarbons, carbon oxide, hydrogen sulfide, and radon. Methane migrating into the lower levels of buildings, garages, cable ducts, and sewage systems reaching the concentrations of above 5% may cause an explosion hazard. The concentration of carbon dioxide over 4% also represents a serious threat to life. Moreover, carbon dioxide and methane, emitted into the atmosphere, constitute a considerable source of greenhouse gases. The methane could be utilized, yet it is necessary to develop effective capture and purification methods with the first step of determination being its migration routes. The paper presents the application of numerical modelling with the use of TOUGHv2.0 software, which enabled effective simulation of the multiphase flow, applying adsorption and diffusion phenomena. The results of gas migration modelling were compared to the outcomes of geological tests, and the obtained results were satisfying. It was observed that both geological investigation and computer simulations are proper tools for investigation of the phenomenon of gas migration and identification of gas hazard areas on the surface, constituting the basis for development of effective methane capture methods for further application.
Deep Hedging under Rough Volatility
Authors: Horvath Blanka , Teichmann Josef , Žurič Žan
Published: July 2021

We investigate the performance of the Deep Hedging framework under training paths beyond the (finite dimensional) Markovian setup. In particular, we analyse the hedging performance of the original architecture under rough volatility models in view of existing theoretical results for those. Furthermore, we suggest parsimonious but suitable network architectures capable of capturing the non-Markoviantity of time-series. We also analyse the hedging behaviour in these models in terms of Profit and Loss (P&L) distributions and draw comparisons to jump diffusion models if the rebalancing frequency is realistically small.
Pre-Launch Radiometric Characterization of EMI-2 on the GaoFen-5 Series of Satellites
Authors: Zhao Minjie , Si Fuqi , Zhou Haijin , Jiang Yu , Ji Chunyan , Wang Shimei , Zhan Kai , Liu Wenqing
Published: July 2021

The environmental trace gas monitoring instrument (EMI) is a space-borne imaging spectrometer onboard GaoFen-5, which was launched in May 2018, covering wavelengths in the range of 240–710 nm to measure NO2, O3, HCHO, and SO2. An advanced EMI-2 instrument with a higher spatial resolution and sufficient signal-to-noise is currently planned for launch on the GaoFen-5(02) satellite in 2021. The EMI-2 instrument bidirectional scattering distribution function (BSDF) is obtained from the absolute irradiance and radiance calibration on-ground. Based on EMI-2 earth and sun optical paths, the key factors of BSDF parameters are introduced. An NIST-calibrated 1000 W FEL quartz tungsten halogen lamp and a 2D turntable are adopted for the absolute irradiance calibration. A large aperture integrating sphere system is used for the absolute radiance calibration. Based on absolute irradiance and radiance calibration functions, the BSDF parameters are obtained, with accuracy of 4.9% for UV1, 4.3% for UV2, 4.1% for VIS1, and 4.2% for VIS2. The on-ground measurement results show that the reflectance spectrum can be calculated from BSDF parameters. On-orbit application of the EMI-2 instrument BSDF are also discussed.
Shallow Shear-Wave Velocity Structure beneath the West Lake Area in Hangzhou, China, from Ambient-Noise Tomography
Authors: Chen Zhongen , Bao Xuewei , Yang Wencai
Published: July 2021

Urban geophysical exploration plays an important role in the sustainable development of and the mitigation of geological hazards in metropolitan areas. However, it is not suitable to implement active seismic methods in densely populated urban areas. The rapidly developing ambient-noise tomography (ANT) method is a promising technique for imaging the near-surface seismic velocity structure. We selected the West Lake area of the city of Hangzhou as a case study to probe the shallow subsurface shear-wave velocity (Vs) structure using ANT. We conducted seismic interferometry on the ambient-noise data recorded by 28 seismograph stations during a time period of 17 days. Fundamental-mode Rayleigh-wave group- and phase-velocity dispersion data were measured from cross-correlation functions and then inverted for a 3D Vs model of the uppermost 1 km that covers an area of about 7 km × 8 km. The tomographic results reveal two prominent anomalies, with high velocities in the southwest and low velocities in the northeast. The fast anomaly corresponds to the presence of limestone and sandstone, whereas the slow anomaly is due to the relatively low-velocity rhyolite and volcanic tuff in the area. The boundary between the two anomalies lies to the NE of an NW–SE trending fault, indicating that the fault dips toward the NE. In addition, the pronounced low-velocity anomalies appear under the Baoshi mountain, likely due to the thick rhyolite and volcanic tuff beneath the extinct volcano. Our results correlate well with regional geological features and suggest that ANT could be a promising technique for facilitating the exploration of urban underground space.
Arc-Induced Long-Period Fiber Gratings at INESC TEC. Part I: Fabrication, Characterization and Mechanisms of Formation
Authors: Rego Gaspar , Caldas Paulo , Ivanov Oleg V.
Published: July 2021

In this work, we reviewed the most important achievements of INESC TEC related to the fabrication of long-period fiber gratings using the electric arc technique. We focused on the fabrication setup, the type of fiber used, and the effect of the fabrication parameters on the gratings’ transmission spectra. The theory was presented, as well as a discussion on the mechanisms responsible for the formation of the gratings, supported by the measurement of the temperature reached by the fiber during an electric arc discharge.
Noninvasive In Vivo Estimation of Blood-Glucose Concentration by Monte Carlo Simulation
Authors: Haque Chowdhury Azimul , Hossain Shifat , Kwon Tae-Ho , Kim Ki-Doo
Published: July 2021

Continuous monitoring of blood-glucose concentrations is essential for both diabetic and nondiabetic patients to plan a healthy lifestyle. Noninvasive in vivo blood-glucose measurements help reduce the pain of piercing human fingertips to collect blood. To facilitate noninvasive measurements, this work proposes a Monte Carlo photon simulation-based model to estimate blood-glucose concentration via photoplethysmography (PPG) on the fingertip. A heterogeneous finger model was exposed to light at 660 nm and 940 nm in the reflectance mode of PPG via Monte Carlo photon propagation. The bio-optical properties of the finger model were also deduced to design the photon simulation model for the finger layers. The intensities of the detected photons after simulation with the model were used to estimate the blood-glucose concentrations using a supervised machine-learning model, XGBoost. The XGBoost model was trained with synthetic data obtained from the Monte Carlo simulations and tested with both synthetic and real data (n = 35). For testing with synthetic data, the Pearson correlation coefficient (Pearson’s r) of the model was found to be 0.91, and the coefficient of determination (R2) was found to be 0.83. On the other hand, for tests with real data, the Pearson’s r of the model was 0.85, and R2 was 0.68. Error grid analysis and Bland–Altman analysis were also performed to confirm the accuracy. The results presented herein provide the necessary steps for noninvasive in vivo blood-glucose concentration estimation.
Antennas and Propagation: A Sensor Approach
Authors: Tamas Razvan D.
Published: July 2021

Antennas are essentially transducers, as they convert electromagnetic fields into signals and vice versa [...]
Experimental Demonstration of 3 × 3 MIMO LED-to-LED Communication Using RGB Colors
Authors: Jung Hyunwoo , Kim Sung-Man
Published: July 2021

Optical wireless communication (OWC) is one of the promising candidates for beyond fifth-generation communication (B5G). Depending on the type of transmitters, receivers, and information carriers applied in the system, OWC can be categorized into visible light communication, light fidelity, free-space optical communication, optical camera communication, etc. In addition to these OWC subcategories, this paper proposes light-emitting diode (LED)-to-LED communication as another subcategory of OWC technique. Furthermore, we show an experimental demonstration of the multiple-input multiple-output (MIMO) LED-to-LED communication system using red, green, and blue colored LEDs. We believe that LED-to-LED communication is an effective solution to resolve the communication burden arising from massive connectivity in B5G internet of things. Along with the measurement results of the transmitter LED, receiver LED, and the channel properties, it is shown that the MIMO LED-to-LED system is able to successfully recover the transmitted signal with low inter-channel interferences due to the receiver LED’s unique characteristics. Finally, the bit error rate (BER) performance of the MIMO LED-to-LED system is shown in comparison with the BER performance of the single-input single-output (SISO) LED-to-LED system. We successfully implemented the 3 × 3 MIMO LED-to-LED communication system using RGB colors at a data rate of 30.62 kbps over a 10 cm transmission distance along with direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) modulation and zero-forcing (ZF) equalizer.
Design of Flow Velocity and Direction Monitoring Sensor Based on Fiber Bragg Grating
Authors: Zhang Hao , Zhong Zhixin , Duan Junmiao , Liu Guangxun , Hu Junhai
Published: July 2021

The real-time monitoring of the flow environment parameters, such as flow velocity and direction, helps to accurately analyze the effect of water scour and provide technical support for the maintenance of pier and abutment foundations in water. Based on the principle of the Fiber Brag Grating sensor, a sensor for monitoring the flow velocity and direction in real-time is designed in this paper. Meanwhile, the theoretical calculation formulas of flow velocity and direction are derived. The structural performance of the sensor is simulated and analyzed by finite element analysis. The performance requirements of different parts of the sensor are clarified. After a sample of the sensor is manufactured, calibration experiments are conducted to verify the function and test the accuracy of the sensor, and the experimental error is analyzed. The experimental results indicate that the sensor designed in this paper achieves a high accuracy for the flow with a flow velocity of 0.05–5 m/s and the flow velocity monitoring error is kept within 7%, while the flow direction monitoring error is kept within 2°. The sensor can meet the actual monitoring requirements of the structures in water and provide reliable data sources for water scour analysis.
A Comprehensive Computer-Assisted Diagnosis System for Early Assessment of Renal Cancer Tumors
Authors: Shehata Mohamed , Alksas Ahmed , Abouelkheir Rasha T. , Elmahdy Ahmed , Shaffie Ahmed , Soliman Ahmed , Ghazal Mohammed , Abu Khalifeh Hadil , Salim Reem , Abdel Razek Ahmed Abdel Khalek , Alghamdi Norah Saleh , El-Baz Ayman
Published: July 2021

Renal cell carcinoma (RCC) is the most common and a highly aggressive type of malignant renal tumor. In this manuscript, we aim to identify and integrate the optimal discriminating morphological, textural, and functional features that best describe the malignancy status of a given renal tumor. The integrated discriminating features may lead to the development of a novel comprehensive renal cancer computer-assisted diagnosis (RC-CAD) system with the ability to discriminate between benign and malignant renal tumors and specify the malignancy subtypes for optimal medical management. Informed consent was obtained from a total of 140 biopsy-proven patients to participate in the study (male = 72 and female = 68, age range = 15 to 87 years). There were 70 patients who had RCC (40 clear cell RCC (ccRCC), 30 nonclear cell RCC (nccRCC)), while the other 70 had benign angiomyolipoma tumors. Contrast-enhanced computed tomography (CE-CT) images were acquired, and renal tumors were segmented for all patients to allow the extraction of discriminating imaging features. The RC-CAD system incorporates the following major steps: (i) applying a new parametric spherical harmonic technique to estimate the morphological features, (ii) modeling a novel angular invariant gray-level co-occurrence matrix to estimate the textural features, and (iii) constructing wash-in/wash-out slopes to estimate the functional features by quantifying enhancement variations across different CE-CT phases. These features were subsequently combined and processed using a two-stage multilayer perceptron artificial neural network (MLP-ANN) classifier to classify the renal tumor as benign or malignant and identify the malignancy subtype as well. Using the combined features and a leave-one-subject-out cross-validation approach, the developed RC-CAD system achieved a sensitivity of 95.3%±2.0%, a specificity of 99.9%±0.4%, and Dice similarity coefficient of 0.98±0.01 in differentiating malignant from benign tumors, as well as an overall accuracy of 89.6%±5.0% in discriminating ccRCC from nccRCC. The diagnostic abilities of the developed RC-CAD system were further validated using a randomly stratified 10-fold cross-validation approach. The obtained results using the proposed MLP-ANN classification model outperformed other machine learning classifiers (e.g., support vector machine, random forests, relational functional gradient boosting, etc.). Hence, integrating morphological, textural, and functional features enhances the diagnostic performance, making the proposal a reliable noninvasive diagnostic tool for renal tumors.
Screen Printing Carbon Nanotubes Textiles Antennas for Smart Wearables
Authors: Ibanez Labiano Isidoro , Arslan Dilan , Ozden Yenigun Elif , Asadi Amir , Cebeci Hulya , Alomainy Akram
Published: July 2021

Electronic textiles have become a dynamic research field in recent decades, attracting attention to smart wearables to develop and integrate electronic devices onto clothing. Combining traditional screen-printing techniques with novel nanocarbon-based inks offers seamless integration of flexible and conformal antenna patterns onto fabric substrates with a minimum weight penalty and haptic disruption. In this study, two different fabric-based antenna designs called PICA and LOOP were fabricated through a scalable screen-printing process by tuning the conductive ink formulations accompanied by cellulose nanocrystals. The printing process was controlled and monitored by revealing the relationship between the textiles’ nature and conducting nano-ink. The fabric prototypes were tested in dynamic environments mimicking complex real-life situations, such as being in proximity to a human body, and being affected by wrinkling, bending, and fabric care such as washing or ironing. Both computational and experimental on-and-off-body antenna gain results acknowledged the potential of tunable material systems complimenting traditional printing techniques for smart sensing technology as a plausible pathway for future wearables.
An Electrochemical Ti3C2Tx Aptasensor for Sensitive and Label-Free Detection of Marine Biological Toxins
Authors: Ullah Najeeb , Chen Wei , Noureen Beenish , Tian Yulan , Du Liping , Wu Chunsheng , Ma Jie
Published: July 2021

Saxitoxin (STX) belongs to the family of marine biological toxins, which are major contaminants in seafood. The reference methods for STX detection are mouse bioassay and chromatographic analysis, which are time-consuming, high costs, and requirement of sophisticated operation. Therefore, the development of alternative methods for STX analysis is urgent. Electrochemical analysis is a fast, low-cost, and sensitive method for biomolecules analysis. Thus, in this study, an electrolyte-insulator-semiconductor (EIS) sensor based on aptamer-modified two-dimensional layered Ti3C2Tx nanosheets was developed for STX detection. The high surface area and rich functional groups of MXene benefited the modification of aptamer, which had specific interactions with STX. Capacitance-voltage (C-V) and constant-capacitance (ConCap) measurement results indicated that the aptasensor was able to detect STX with high sensitivity and good specificity. The detection range was 1.0 nM to 200 nM and detection limit was as low as 0.03 nM. Moreover, the aptasensor was found to have a good selectivity and two-week stability. The mussel tissue extraction test suggested the potential application of this biosensor in detecting STX in real samples. This method provides a convenient approach for low-cost, rapid, and label-free detection of marine biological toxins.
Water Extraction Method Based on Multi-Texture Feature Fusion of Synthetic Aperture Radar Images
Authors: Zhu Wenbin , Dai Zheng , Gu Hong , Zhu Xiaochun
Published: July 2021

Lakes play an important role in the water ecosystem on earth, and are vulnerable to climate change and human activities. Thus, the detection of water quality changes is of great significance for ecosystem assessment, disaster warning and water conservancy projects. In this paper, the dynamic changes of the Poyang Lake are monitored by Synthetic Aperture Radar (SAR). In order to extract water from SAR images to monitor water change, a water extraction algorithm composed of texture feature extraction, feature fusion and target segmentation was proposed. Firstly, the fractal dimension and lacunarity were calculated to construct the texture feature set of a water object. Then, an iterated function system (IFS) was constructed to fuse texture features into composite feature vectors. Finally, lake water was segmented by the multifractal spectrum method. Experimental results showed that the proposed algorithm accurately extracted water targets from SAR images of different regions and different imaging modes. Compared with common algorithms such as fuzzy C-means (FCM), the accuracy of the proposed algorithm is significantly improved, with an accuracy of over 98%. Moreover, the proposed algorithm can accurately segment complex coastlines with mountain shadow interference. In addition, the dynamic analysis of the changes of the water area of the Poyang Lake Basin was carried out with the local hydrological data. It showed that the extracted results of the algorithm in this paper are a good match with the hydrological data. This study provides an accurate monitoring method for lake water under complex backgrounds.
Reusing Geopolymer Waste from Matrices Based on Metakaolin or Fly Ash for the Manufacture of New Binder Geopolymeric Matrices
Authors: Hattaf Rabii , Aboulayt Abdelilah , Samdi Azzedine , Lahlou Nouha , Ouazzani Touhami Mohamed , Gomina Moussa , Moussa Redouane
Published: July 2021

The increasing use of geopolymer materials in the construction and civil engineering sectors generates a large amount of non-biodegradable waste that will end up in landfills. It is therefore necessary to anticipate solutions for the proper management of this waste. In this work, new geopolymer materials were fabricated by partially replacing the reactive raw minerals (fly ash, FA, or metakaolin, MK) with used geopolymers (fully fly ash-based, FAref, or metakaolin-based, MKref), in order to develop a strategy to reuse geopolymer waste. Their workability and setting behavior were studied in the fresh state, and the geopolymerization process was investigated by calorimetry and by electrochemistry. Mechanical properties and the ability for coating mineral aggregates were assessed, and the resulting adhesion properties were analyzed using matrix/sand mortars. It appears that the new geopolymer materials as well as the mortars are endowed with good performances. The compressive strengths are above 50 MPa and therefore meet the requirements of different construction materials. This demonstrates the recyclability of geopolymer materials. Moreover, an analysis of the influence of the substitution of recycled geopolymers on the setting and on the mechanical performances of mortars makes it possible to propose a binder-recycled geopolymer interaction model for the formation of new binding matrices.
Recycled Asphalt Pavement Materials in Transport Pavement Infrastructure: Sustainability Analysis & Metrics
Authors: Zhao Yunpeng , Goulias Dimitrios , Peterson Dominique
Published: July 2021

Transportation infrastructure is one of the largest consumers of natural materials. To improve the environmental quality and sustainable development of transportation infrastructure, it is important to implement sustainable strategies in pavement construction and rehabilitation. The use of recycled materials is a key element in generating sustainable pavement designs to save natural resources, reduce energy, greenhouse gas emissions, and costs. The objective of this study was to propose a methodology for assessing the environmental and economic life-cycle benefits when using recycled asphalt pavement (RAP) materials in highway projects. Previous studies on life cycle analysis (LCA) using RAP focused on the economics and/or environmental impacts during the material production process. Thus, there is a need to consider sustainability analysis at all stages of construction and rehabilitation during the performance period of pavement structures. This study addresses this need with the proposed methodology. The suggested approach could be potentially implemented in a pavement management system (PMS) so as to introduce sustainability principles in optimizing alternative rehabilitation strategies. The methodology includes various steps for the analysis, starting with condition assessment of the existing highway, identifying alternative structural pavement designs, predicting service life, setting up alternative rehabilitation strategies, and conducting life cycle environmental and economic analysis. To demonstrate the value of the methodology, a comparative parametric study was conducted on two real case study projects representing actual field conditions for primary roads in Maryland. These case studies were used in order to quantify the economic savings and environmental benefits of using different levels of RAP in highway rehabilitation. The results of the analysis indicate that incorporating RAP in pavement rehabilitation can contribute substantially to cost savings and environmental impact reduction (e.g., greenhouse gas emission, energy, water, and hazardous waste). The benefits illustrated in this study are expected to encourage wide adoption of the proposed methodology and the use of recycled materials in highway construction and rehabilitation. The methodology is transferable where similar materials and highway construction techniques are used.
Evaluating STEM-Based Sustainability Understanding: A Cognitive Mapping Approach
Authors: Petrun Sayers Elizabeth L. , Craig Christopher A. , Skonicki Emily , Gahlon Grace , Gilbertz Susan , Feng Song
Published: July 2021

Management education holds promise for addressing deficiencies in interuniversity science, technology, engineering, and mathematics (STEM), as well as sustainability curricula. Accordingly, we designed, developed, implemented, and longitudinally evaluated interdisciplinary STEM-based curricula in the United States. Students in five sections of business management courses and two sections of STEM courses received a STEM-based sustainability intervention (i.e., an interdisciplinary STEM and sustainability module). To assess student outcomes following the intervention and examine the feasibility of cognitive mapping as a student learning assessment tool, we implemented a pre- and post-course modified cognitive mapping assessment in treatment and comparison courses. To interpret the results, we ran descriptives, correlations, paired sample t tests, and principal component analysis. The t tests suggest that when all coding categories are considered, those participating in curricular interventions listed significantly more sustainability terms. The principal component analysis results demonstrate that treatment courses improved variability explained by 7.23% between pre- and post-tests but declined by 8.22% for comparison courses. Overall, linkages became stronger between parent code categories for treatment courses and weaker for comparison courses. These findings add to existing research related to cognitive mapping and demonstrate the ability of the method to capture changes in student outcomes after exposure to STEM-based sustainability curriculum.
Adaptive Reuse and Sustainability Protocols in Italy: Relationship with Circular Economy
Authors: Marika Gaballo , Beatrice Mecca , Francesca Abastante
Published: July 2021

This paper explores the enhancement of adaptive reuse (AR) of buildings through the lens of the sustainability protocols within the context of circular economy (CE) in Italy. Cities and the built environment can play a key role in the transition to a CE, especially considering the documented negative global impact due to resource consumption and waste generation. This is recognised among the principles of circularity defined by the European Commission towards a general strategy for a sustainable built environment, which encourages initiatives of building reuse and land consumption reduction. It has been proven that the AR of vacant buildings can bring environmental, social, and economic benefits towards an urban strategy based on CE principles by generating useful values to support innovative development dynamics. In this perspective, the sustainability protocols can be identified as useful tools to pursue strategies for spreading the culture of sustainable build environment. Considering the huge vacant Italian architectural heritage, this paper aims to analyze how the most widely used sustainability protocols in the Italian context currently address the enhancement of the reuse of buildings, to improve environmental, social, and economic quality in the built environment. We discuss the results highlighting how and which sustainability protocols better intercept these issues, providing grounds for future development.
Data Integration for Diet Sustainability Analyses
Authors: Conrad Zach , Stern Alexandra , Love David C. , Salesses Meredith , Cyril Ashley , McDowell Acree , Blackstone Nicole Tichenor
Published: July 2021

Diet sustainability analyses are stronger when they incorporate multiple food systems domains, disciplines, scales, and time/space dimensions into a common modeling framework. Few analyses do this well: there are large gaps in food systems data in many regions, accessing private and some public data can be difficult, and there are analytical challenges, such as creating linkages across datasets and using complex analytical methods. This article summarizes key data sources across multiple domains of food system sustainability (nutrition, economic, environment) and describes methods and tools for integrating them into a common analytic framework. Our focus is the United States because of the large number of publicly available and highly disaggregated datasets. Thematically, we focus on linkages that exist between environmental and economic datasets to nutrition, which can be used to estimate the cost and agricultural resource use of food waste, interrelationships between healthy eating and climate impacts, diets optimized for cost, nutrition, and environmental impacts, and others. The limitations of these approaches and data sources are described next. By enhancing data integration across these fields, researchers can be better equipped to promote policy for sustainable diets.
Scenario Simulation of the Impact of China’s Free-Trade Zone Construction on Regional Sustainable Development: A Case Study of the Pearl River Delta Urban Agglomeration
Authors: Liu Xiaofei , Wang Zhenbo , Cui Xuegang
Published: July 2021

Regional sustainable development is a complex process driven by multiple factors, such as the economy, society, and environment. China has made a series of major adjustments and devised plans, including the establishment of a pilot free-trade zone, to promote regional sustainable development. The pilot free-trade zone, characterized by free trade and the opening up of institutions, changes the path and mode of regional sustainable development to a certain extent. However, an effective empirical quantitative analysis to verify the impact of the pilot free-trade zone on regional sustainable development is lacking. This paper employs the system dynamics method to predict the social–economic–environmental development trends and key control factors of the Pearl River Delta urban agglomeration by considering the unique advantages of system dynamics. The construction of a pilot free-trade zone was set as a control variable to analyze its promoting effect on regional sustainable development. Next, the most suitable model for sustainable development for the future was determined. The results indicate that the construction of the pilot free-trade zone led to significant growth in indicators such as import and export trade, total economic volume, income, and labor force, all of which are conducive to regional sustainable development. Practically, the simulation results provide decision support for promoting the sustainable development of the Pearl River Delta urban agglomeration.
Envisioning Happy Places for All: A Systematic Review of the Impact of Transformations in the Urban Environment on the Wellbeing of Vulnerable Groups
Authors: Cassarino Marica , Shahab Sina , Biscaya Sara
Published: July 2021

Urban planning and design can impact mental health, but it is unclear how ever-growing and changing cities can sustain the psychological wellbeing of vulnerable groups, who are among the most mentally sensitive to spatial inequalities. This systematic review synthesised quantitative and qualitative studies on urban design interventions and their impact on wellbeing in vulnerable groups. Using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, we searched five online databases from inception to May 2020. A total of 10 papers were included. We found mixed evidence of benefits for wellbeing linked to urban regeneration projects or focused interventions (green spaces, transport, security). Interventions that were centred around participation, sustainable living, and quality of design (e.g., perceived sense of safety) were associated with increased residential satisfaction and wellbeing, particularly among low-income communities and women. Risk of bias was low to medium, but there was high methodological heterogeneity; studies were mainly from Western countries, and none of the included studies investigated the experiences of people with disabilities, migrants, or racial minorities. This review highlights the importance of inclusive and sustainable design interventions to create happy places for all strata of society, although further investigation is warranted.
Spatial Analysis of Mangrove Forest Management to Reduce Air Temperature and CO2 Emissions
Authors: Sumarmi Sumarmi , Purwanto Purwanto , Bachri Syamsul
Published: July 2021

Surabaya is a coastal city that is still developing. Like other developing cities, Surabaya highly suppresses mangrove forests for residential, industrial, and other areas. Mangrove forests supply oxygen for the population of Surabaya. Forest mangroves reduce the effects of global warming and preserve sustainable coastal ecosystems. This research aimed to (1) map temperature changes in Surabaya over a period of 20 years (1996–2016) by using remote sensing and GIS, and (2) examine mangrove forests’ ability to absorb CO2 and decrease the impact of global warming in Surabaya. Research results showed that: (1) on the basis of the analysis of the temperature surface area, temperatures changed significantly between 1996 and 2016. Temperature changes can be classified into low, moderate, or high. The low-temperature area of 21–30 °C followed a different pattern. Each year, changes in the high-surface-temperature area were in the range of 31–42 °C. Changes highly increased in the period of 2006–2016. This indicates that Surabaya experienced a significant temperature increase in 2016. (2) There was correlation between the change in mangrove forest cover and the change in temperature; CO2 concentration in mangrove, vegetation, and water areas decreased as it grew in areas used for construction, such as factories, residences, and roads. CO2 concentration in Surabaya showed a distribution in the “high” and “extremely high” categories. The high category was 27.5%, and the extremely high category was 67.5%. The sample point in both the moderate and low category was around 25%.
Improved Adaptive Hamiltonian Control Law for Constant Power Load Stability Issue in DC Microgrid: Case Study for Multiphase Interleaved Fuel Cell Boost Converter
Authors: Thounthong Phatiphat , Mungporn Pongsiri , Nahid-Mobarakeh Babak , Bizon Nicu , Pierfederici Serge , Guilbert Damien
Published: July 2021

The cascaded connection of power converters in a DC microgrid may cause instabilities. Indeed, power converters operating as external loads exhibit constant power load (CPL) behaviors. In this study, the design of the feedback controller of a multi–cell interleaved fuel cell (FC) step–up power circuit is based on the adaptive Hamiltonian control law. It includes two integral terms to confirm that there is no steady-state error in the DC bus voltage, and to guarantee the current balancing of each input inductor current. The design confirms that the desired equilibrium point is (locally) asymptotically stable by using the Lyapunov stability proof. The control approach is validated via digital simulations and experimental tests performed with a 2500 W FC converter supplied by an FC/reformer size of 2500 W and 50 V.
Environmental Sustainability and the Inclusion of Geomorphosites in Tourist Activity—Case Study: The Baiului Mountains, Romania
Authors: Barbălată (Alb) Ligia , Comănescu Laura
Published: July 2021

This paper presents the sustainability of the relief at geomorphosites in terms of tourist activity and how tourism can affect the relief by presenting the major sustainable tourism issues. For the study area, the Baiului Mountains from Romania were chosen. In addition, we present the method for assessing tourist and exploitation values of geomorphological sites in the tourist area of Romania. Jean-Pierre Pralong first used the method and it aims to qualify the potential in terms of scenic, scientific, cultural and economic values and the use of this potential in terms of degree and modality of exploitation. It was based on the study of 10 geomorphological sites in the area of the Baiului Mountains. We present each geomorphosite and its scale for every value. Finally, we develop an analysis of the potential and use of the studied geomorphosites and the relationship between the reliefs and tourism.
Mix Design Effects on the Durability of Alkali-Activated Slag Concrete in a Hydrochloric Acid Environment
Authors: Teymouri Mohammad , Behfarnia Kiachehr , Shabani Amirhosein
Published: July 2021

Because of its high strength, energy reduction, and low environmental impact, researchers have encouraged considering alkali-activated slag concrete (AASC) as a potential alternative to conventional concrete. In this study, the impact of mix design parameters on the durability of AASC, made with ground granulated blast furnace slag and activated with different alkaline solutions (NaOH, KOH, and Na2SiO3) immersed up to six months in a hydrochloric acid bath with pH = 3, has been investigated. A total of 13 mix designs were made in a way that, in addition to the type of alkaline solution, considered three other parameters, namely the molarity of alkaline solutions, the weight ratio of alkaline solutions to slag, and the weight ratio of alkaline solutions to sodium silicate. Visual inspections displayed that the AASC samples almost remained intact after exposure to an HCl acid solution with pH = 3 for up to 6 months, while the OPC sample experienced deleterious deterioration. The results clearly show that AASC outperformed OPC concrete when it comes to durability in an HCl acid solution. The strength reduction and weight loss of AASC compared with OPC concrete were approximately one-tenth and one-fifth, respectively. The AASC samples containing potassium hydroxide showed a higher strength reduction and weight loss in the HCl acid solution than the samples made with sodium hydroxide.
The Attractiveness of Urban Complexes: Economic Aspect and Risks of Environmental Pollution
Authors: Trifković Milan , Kuburić Miroslav , Nestorović Žarko , Jovanović Goca , Kekanović Milan
Published: July 2021

Urbanization and intensive economic activities and growth are closely related. On the other hand, the economic, especially industrial activities cause the pollution of urban areas. In spite of that risk for human health, people strive to live in conditions which offer more chances for improved quality of life. In this paper the connection between the economic chances and healthy risk issues are investigated. To determine the rate of attractiveness of urban complexes the authors introduced the relation between gross domestic product of urban area and the air quality index, called economic attractiveness of urban area. This ratio is quite stable because changes of gross domestic product per capita and air quality index are not expected to be too dynamic and unpredictable. Additionally, the errors in the measuring of gross domestic product and air quality index are quite small and could not affect the result significantly. The results showed that correlation between gross domestic product and air quality index is negative, i.e., that higher gross domestic product per capita (GDP/c) is related with lower air quality index which means greater quality of air. In addition, the coefficient of economic attractiveness showed that urban areas with highest gross domestic product do not have to be the most attractive areas if the air quality index is higher.