bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of CaCO3 Nanoparticles on the Mechanical and Photo-Degradation Properties of LDPE
Authors: Zapata Paula , Palza Humberto , Díaz Boris , Armijo Andrea , Sepúlveda Francesca , Ortiz J. , Ramírez Maria , Oyarzún Claudio
Published: December 2018

CaCO3 nanoparticles of around 60 nm were obtained by a co-precipitation method and used as filler to prepare low-density polyethylene (LDPE) composites by melt blending. The nanoparticles were also organically modified with oleic acid (O-CaCO3) in order to improve their interaction with the LDPE matrix. By adding 3 and 5 wt% of nanofillers, the mechanical properties under tensile conditions of the polymer matrix improved around 29%. The pure LDPE sample and the nanocomposites with 5 wt% CaCO3 were photoaged by ultraviolet (UV) irradiation during 35 days and the carbonyl index (CI), degree of crystallinity (χc), and Young’s modulus were measured at different times. After photoaging, the LDPE/CaCO3 nanocomposites increased the percent crystallinity (χc), the CI, and Young’s modulus as compared to the pure polymer. Moreover, the viscosity of the photoaged nanocomposite was lower than that of photoaged pure LDPE, while scanning electron microscopy (SEM) analysis showed that after photoaging the nanocomposites presented cavities around the nanoparticles. These difference showed that the presence of CaCO3 nanoparticles accelerate the photo-degradation of the polymer matrix. Our results show that the addition of CaCO3 nanoparticles into an LDPE polymer matrix allows future developments of more sustainable polyethylene materials that could be applied as films in agriculture. These LDPE-CaCO3 nanocomposites open the opportunity to improve the low degradation of the LDPE without sacrificing the polymer’s behavior, allowing future development of novel eco-friendly polymers.
New Alkoxy Flavone Derivatives Targeting Caspases: Synthesis and Antitumor Activity Evaluation
Authors: Moreira Joana , Ribeiro Diana , Silva Patrícia M. A. , Nazareth Nair , Monteiro Madalena , Palmeira Andreia , Saraiva Lucília , Pinto Madalena , Bousbaa Hassan , Cidade Honorina
Published: December 2018

The antitumor activity of natural flavonoids has been exhaustively reported. Previously it has been demonstrated that prenylation of flavonoids allows the discovery of new compounds with improved antitumor activity through the activation of caspase-7 activity. The synthesis of twenty-five flavonoids (4–28) with one or more alkyl side chains was carried out. The synthetic approach was based on the reaction with alkyl halide in alkaline medium by microwave (MW) irradiation. The in vitro cell growth inhibitory activity of synthesized compounds was investigated in three human tumor cell lines. Among the tested compounds, derivatives 6, 7, 9, 11, 13, 15, 17, and 18 revealed potent growth inhibitory activity (GI50 < 10 μM), being the growth inhibitory effect of compound 13 related with a pronounced caspase-7 activation on MCF-7 breast cancer cells and yeasts expressing human caspase-7. A quantitative structure-activity relationship (QSAR) model predicted that hydrophilicity, pattern of ring substitution/shape, and presence of partial negative charged atoms were the descriptors implied in the growth inhibitory effect of synthesized compounds. Docking studies on procaspase-7 allowed predicting the binding of compound 13 to the allosteric site of procaspase-7.
A New Polyoxygenated Flavonol Gossypetin-3-O-β-d-Robinobioside from Caesalpinia gilliesii (Hook.) D. Dietr. and In Vivo Hepatoprotective, Anti-Inflammatory, and Anti-Ulcer Activities of the Leaf Methanol Extract
Authors: Emam Mahmoud , El Raey Mohamed A. , El-Haddad Alaadin E. , El Awdan Sally A. , Rabie Abdel-Gawad M. , El-Ansari Mohamed A. , Sobeh Mansour , Osman Samir M. , Wink Michael
Published: December 2018

A hitherto unknown polyoxygenated flavonol robinobioside (gossypetin-3-O-β-d-robinobioside) was isolated from the leaves of Caesalpinia gilliesii along with thirteen known phenolic secondary metabolites. The isolated compounds were characterized using spectroscopic analysis, including 1D and 2D NMR and mass spectrometry (MS) analyses. The extract reduced the level of liver damage in CCl4-induced liver injury in rats. A decrease of the liver biomarkers—aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and an increase of total antioxidant capacity (TAC) levels—were observed similar to the liver protecting drug silymarin. In addition, the extract showed promising activity against carrageenan-induced paw edema in rats and protected their stomachs against ethanol-induced gastric ulcers in a concentration dependent fashion. The observed activities could be attributed to the high content of antioxidant polyphenols. Our results suggest that the C. gilliesii has the capacity to scavenge free radicals and can protect against oxidative stress, and liver and stomach injury.
Electrochemical Deposition of Gold Nanoparticles on Reduced Graphene Oxide by Fast Scan Cyclic Voltammetry for the Sensitive Determination of As(III)
Authors: Zhao Guo , Liu Gang
Published: December 2018

In this study, a stable, sensitive electrochemical sensor was fabricated by the electrochemical codeposition of reduced graphene oxide (rGO) and gold nanoparticles on a glassy carbon electrode (rGO-Aunano/GCE) using cyclic voltammetry (CV), which enabled a simple and controllable electrode modification strategy for the determination of trace As(III) by square wave anodic stripping voltammetry (SWASV). SWASV, CV, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the electrochemical properties and morphology of the proposed sensing platform. The number of sweep segments, the deposition potential and the deposition time were optimized to obtain ideal sensitivity. The presence of rGO from the electroreduction of graphene oxide on the sensing interface effectively enlarged the specific surface area and consequently improved the preconcentration capacity for As(III). The rGO-Aunano/GCE sensor exhibited outstanding detection performance for As(III) due to the combined effect of Aunano and rGO formed during the electroreduction process. Under the optimized conditions, a linear range from 13.375 × 10−9 to 668.75 × 10−9 mol/L (1.0 to 50.0 μg/L) was obtained with a detection limit of 1.07 × 10−9 mol/L (0.08 μg/L) (S/N = 3). The reproducibility and reliability of the rGO-Aunano/GCE sensor were also verified by performing 8 repetitive measurements. Finally, the rGO-Aunano/GCE sensor was used for the analysis of real samples with satisfactory results.
First Generation Amperometric Biosensing of Galactose with Xerogel-Carbon Nanotube Layer-By-Layer Assemblies
Authors: Labban Najwa , Wayu Mulugeta B. , Steele Ciara M. , Munoz Tess S. , Pollock Julie A. , Case William S. , Leopold Michael C.
Published: December 2018

A first-generation amperometric galactose biosensor has been systematically developed utilizing layer-by-layer (LbL) construction of xerogels, polymers, and carbon nanotubes toward a greater fundamental understanding of sensor design with these materials and the potential development of a more efficient galactosemia diagnostic tool for clinical application. The effect of several parameters (xerogel silane precursor, buffer pH, enzyme concentration, drying time and the inclusion of a polyurethane (PU) outer layer) on galactose sensitivity were investigated with the critical nature of xerogel selection being demonstrated. Xerogels formed from silanes with medium, aliphatic side chains were shown to exhibit significant enhancements in sensitivity with the addition of PU due to decreased enzyme leaching. Semi-permeable membranes of diaminobenzene and resorcinol copolymer and Nafion were used for selective discrimination against interferent species and the accompanying loss of sensitivity with adding layers was countered using functionalized, single-walled carbon nanotubes (CNTs). Optimized sensor performance included effective galactose sensitivity (0.037 μA/mM) across a useful diagnostic concentration range (0.5 mM to 7 mM), fast response time (~30 s), and low limits of detection (~80 μM) comparable to literature reports on galactose sensors. Additional modification with anionic polymer layers and/or nanoparticles allowed for galactose detection in blood serum samples and additional selectivity effectiveness.
Investigation of Bunch Compressor and Compressed Electron Beam Characteristics by Coherent Transition Radiation
Authors: Suphakul Sikharin , Zen Heishun , Kii Toshiteru , Ohgaki Hideaki
Published: December 2018

A magnetic chicane bunch compressor for a new compact accelerator-based terahertz (THz) radiation source at the Institute of Advanced Energy, Kyoto University, was completely installed in March 2016. The chicane is employed to compress an electron bunch with an energy of 4.6 MeV generated by a 1.6-cell photocathode radio frequency (RF)-gun. The compressed bunch is injected into a short planar undulator for THz generation by coherent undulator radiation (CUR). The characteristics of the bunch compressor and the compressed bunch were investigated by observing the coherent transition radiation (CTR). The CTR spectra, which were analyzed by using a Michelson interferometer, and the compressed bunch length were also estimated. The results were that the chicane could compress the electron bunch at a laser injection phase less than 45 degrees, and the maximum CTR intensity was observed at a laser injection phase around 24 degrees. The optimum value of the first momentum compaction factor was around −45 mm, which provided an estimated rms bunch length less than 1 ps.
Patterning the Axes: A Lesson from the Root
Authors: Di Mambro Riccardo , Sabatini Sabrina , Dello Ioio Raffaele
Published: December 2018

How the body plan is established and maintained in multicellular organisms is a central question in developmental biology. Thanks to its simple and symmetric structure, the root represents a powerful tool to study the molecular mechanisms underlying the establishment and maintenance of developmental axes. Plant roots show two main axes along which cells pass through different developmental stages and acquire different fates: the root proximodistal axis spans longitudinally from the hypocotyl junction (proximal) to the root tip (distal), whereas the radial axis spans transversely from the vasculature tissue (centre) to the epidermis (outer). Both axes are generated by stereotypical divisions occurring during embryogenesis and are maintained post-embryonically. Here, we review the latest scientific advances on how the correct formation of root proximodistal and radial axes is achieved.
Self-Healable Supramolecular Vanadium Pentoxide Reinforced Polydimethylsiloxane-Graft-Polyurethane Composites
Authors: Berkem Ali Sabri , Capoglu Ahmet , Nugay Turgut , Sancaktar Erol , Anac Ilke
Published: December 2018

The self-healing ability can be imparted to the polymers by different mechanisms. In this study, self-healing polydimethylsiloxane-graft-polyurethane (PDMS-g-PUR)/Vanadium pentoxide (V2O5) nanofiber supramolecular polymer composites based on a reversible hydrogen bonding mechanism are prepared. V2O5 nanofibers are synthesized via colloidal route and characterized by XRD, SEM, EDX, and TEM techniques. In order to prepare PDMS-g-PUR, linear aliphatic PUR having one –COOH functional group (PUR-COOH) is synthesized and grafted onto aminopropyl functionalized PDMS by EDC/HCl coupling reaction. PUR-COOH and PDMS-g-PUR are characterized by 1H NMR, FTIR. PDMS-g-PUR/V2O5 nanofiber composites are prepared and characterized by DSC/TGA, FTIR, and tensile tests. The self-healing ability of PDMS-graft-PUR and composites are determined by mechanical tests and optical microscope. Tensile strength data obtained from mechanical tests show that healing efficiencies of PDMS-g-PUR increase with healing time and reach 85.4 ± 1.2 % after waiting 120 min at 50 °C. The addition of V2O5 nanofibers enhances the mechanical properties and healing efficiency of the PDMS-g-PUR. An increase of healing efficiency and max tensile strength from 85.4 ± 1.2% to 95.3 ± 0.4% and 113.08 ± 5.24 kPa to 1443.40 ± 8.96 kPa is observed after the addition of 10 wt % V2O5 nanofiber into the polymer.
Synthesis of Diblock Polyampholyte PAMPS-b-PMAPTAC and Its Adsorption on Bentonite
Authors: Lin Ling , Luo Yuanhao , Li Xin
Published: December 2018

To study the adsorption of polyampholyte on bentonite (Bent), a block polyampholyte, PAMPS-b-PMAPTAC, comprised of 2-Acrylamido-2-Methylpropane Sulfonic Acid (AMPS) units and Methacrylamido Propyl Trimethyl Ammonium Chloride (MAPTAC) units, was synthesized using reversible addition-fragmentation chain transfer polymerization (RAFT) method. The block polyampholyte samples were characterized by FTIR, 1H NMR and Gel Permeation Chromatography (GPC). The microstructure of block polyampholyte and random polyampholyte in deionized water indicated that uneven distribution of charged groups increased the entanglement of polymer chains. Addition of salt weakened the electrostatic interactions among charged groups, and, therefore, increased the zeta potential of polyampholyte in aqueous solutions. The adsorptive behaviors of PAMPS-b-PMAPTAC on Bent were studied using elemental analysis, and the effects of external factors were considered. The adsorption equilibrium of polymers on Bent was reached after 12 h. Increased temperature and increased salinity exerted a positive and negative effect on the adsorption of polyampholyte, respectively. The molecular weight played as the decisive factor for the adsorption of polyampholyte in the absence of NaCl, while the content of cationic groups acted as the main factor in the presence of NaCl. Block polyampholyte exhibited higher adsorption than random polyampholyte in the absence of salt. XRD results also indicated that block polyampholyte had a better intercalation effect than random polyampholyte.
Characterization of Pores and Fractures in Soft Coal from the No. 5 Soft Coalbed in the Chenghe Mining Area
Authors: Wei Pan , Liang Yunpei , Zhao Song , Peng Shoujian , Li Xuelong , Meng Ran
Published: December 2018

The characteristics of the pore structure and gas migration in soft coalbeds are the premise of evaluating gas discharge in soft coalbeds. To explore the pore structure characteristics of soft coal masses, the No. 5 soft coalbed in the eastern zone of Chenghe Mining Area, was investigated and compared with the No. 5 hard coalbed in the western zone. By using a mercury intrusion method, low-temperature liquid nitrogen adsorption, and scanning electron microscopy (SEM), the pore structure characteristics of the No. 5 coalbed were explored. Moreover, based on fractal theory, the pore structure of coal was characterized. The results showed the pores in soft coal mainly appeared as small pores and micropores in which the small pores accounted for nearly half of the total pore volume. Mesopores and macropores were also distributed throughout the soft coal. The mercury-injection and mercury-ejection curves of soft coal showed significant hysteresis loops, implying that pores in coal samples were mainly open while the mercury-injection curve of hard coal was consistent with its mercury-ejection curve, showing no hysteresis loop while having an even segment, which indicated that closed pores occupied the majority of the pore volume in the coal samples. The curves of low-temperature nitrogen adsorption of soft coal all follow an IV-class isotherm. Moreover, the fractal dimensions of soft coal are respectively larger than the fractal dimensions of hard coal. It can be seen that the characterization of pores and fractures of the soft coal was different from the hard coal in the western distinct of the old mining area. The gas prevention and control measures of soft coal should be formulated according to local conditions.
Economic Feasibility Analysis of Shale Gas Extraction from UK’s Carboniferous Bowland-Hodder Shale Unit
Authors: Ahmed Muhammad , Rezaei-Gomari Sina
Published: December 2018

For many years, shale gas exploitation has been generating contradictory views in the UK and remains subject of rising debates throughout these years. Favorably backed by the government, looking upon it as potential mechanism for gas import independency and competitiveness in global gas industry while strongly opposed by stakeholders (mainly public), idea of shale gas exploitation remains disputed with no substantial progress in past years. And this irresolution is worsened by obscurity of estimates for potential reserves and conflicting assessments on potential impact of shale gas. Yet, in case shale industry is signaled to search and extract resources, there remains another scrutiny stage that shale industry will be subjected to i.e., its extraction must be economically feasible as extracting unconventional resources is financially expensive and riskier than conventional. Hence, this study aims at analyzing the economics of UK’s most prolific Bowland shale play development by a financial model that discovers gas prices range required to earn capital cost on investment in Bowland shale play and is tested on three development plans where it determines that based on given set of hypothesis and past decade’s average gas price of $6.52/Mcf, none of the development plans hold enough probability of adding value, however, hybrid plan formulated by combination of consistent drilling and refracturing proves as economically sustainable with a RGP mean $7.21/Mcf, significantly lower than $9.76/Mcf mean for ‘drilling only’ plan. It is found that required gas price is most sensitive to initial production rate and drilling costs where ±10% variation offsets RGP by ≈ ±8% and ±7%.
Renewable Energy as an Underutilised Resource in Cities: Germany’s ‘Energiewende’ and Lessons for Post-Brexit Cities in the United Kingdom
Authors: Sait Mohammed Adil , Chigbu Uchendu Eugene , Hamiduddin Iqbal , De Vries Walter Timo
Published: December 2018

Renewable energy remains an underutilised resource within urban environments. This study examines the ongoing German Energiewende (energy transition) as an example of renewable energy being treated as a necessary resource for urban development. It departs from existing literature by operationalising the Advocacy Coalition Framework (ACF), taking a policy systems approach to analyse (and explain) the cases of three German cities—Munich, Berlin, and Freiburg. This approach helps draw lessons for future UK energy scenarios by placing more abstract conceptions of Sustainable Energy Transitions (SETs) within the context of UK cities, post-Brexit. By discussing five main themes: the shift from government to governance; the need to break ‘carbon lock-in’; renewable energy innovation as an underutilised resource; developing governance strategies for renewable energy resources; the shift from policy to practice, the study yields a detailed reconceptualisation of approaches to renewable energy resource-use policy. The novelty of this study lies in its response to these challenges, taking a policy systems approach to energy governance. The article concludes with a proposed integrated framework. The framework, which is based on multi-scalar and multi-stakeholder integrated energy governance strategy, reconsiders the way in which renewable energy resources are seen in current governance terms in the UK. The framework presents a new approach to renewable energy resource-use policy that embraces innovation, responsible governance, and inclusive processes, (alongside thinking beyond simply technical solutions) to considering the socio-economic impacts of policy decisions in cities.
The Preliminary Results for Five-System Ultra-Rapid Precise Orbit Determination of the One-Step Method Based on the Double-Difference Observation Model
Authors: Ye Fei , Yuan Yunbin , Tan Bingfeng , Deng Zhiguo , Ou Jikun
Published: December 2018

The predicted parts of ultra-rapid orbits are important for (near) real-time Global Navigation Satellite System (GNSS) precise applications; and there is little research on GPS/GLONASS/BDS/Galileo/QZSS five-system ultra-rapid precise orbit determination; based on the one-step method and double-difference observation model. However; the successful development of a software platform for solving five-system ultra-rapid orbits is the basis of determining and analyzing these orbits. Besides this; the different observation models and processing strategies facilitate to validate the reliability of the various ultra-rapid orbits. In this contribution; this paper derives the double-difference observation model of five-system ultra-rapid precise orbit determination; based on a one-step method; and embeds this method and model into Bernese v5.2; thereby forming a new prototype software platform. For validation purposes; 31 days of real tracking data; collected from 130 globally-distributed International GNSS Service (IGS) multi-GNSS Experiment (MGEX) stations; are used to determine a five-system ultra-rapid precise orbit. The performance of the software platform is evaluated by analysis of the orbit discontinuities at day boundaries and by comparing the consistency with the MGEX orbits from the Deutsches GeoForschungsZentrum (GFZ); between the results of this new prototype software platform and the ultra-rapid orbit provided by the International GNSS Monitoring and Assessment System (iGMAS) analysis center (AC) at the Institute of Geodesy and Geophysics (IGG). The test results show that the average standard deviations of orbit discontinuities in the three-dimension direction are 0.022; 0.031; 0.139; 0.064; 0.028; and 0.465 m for GPS; GLONASS; BDS Inclined Geosynchronous Orbit (IGSO); BDS Mid-Earth Orbit (MEO); Galileo; and QZSS satellites; respectively. In addition; the preliminary results of the new prototype software platform show that the consistency of this platform has been significantly improved compared to the software package of the IGGAC.
Earth Observation Actionable Information Supporting Disaster Risk Reduction Efforts in a Sustainable Development Framework
Authors: Lorenzo-Alonso Alberto , Utanda Ángel , Aulló-Maestro María E. , Palacios Marino
Published: December 2018

Disaster risk reduction (DRR) is a high priority on the agenda of main stakeholders involved in sustainable development, and earth observation (EO) can provide useful, timely, and economical information in this context. This short communication outlines the European Space Agency’s (ESA) specific initiative to promote the use and uptake of satellite data in the global development community: Earth Observation for Sustainable Development (EO4SD). One activity area under EO4SD is devoted to disaster risk reduction (EO4SD DRR). Within this project, a team of European companies and institutions are tasked to develop EO services for supporting the implementation of DRR in International Financial Institutions’ (IFI) projects. Integration of satellite-borne data and ancillary data to generate insight and actionable information is thereby considered a key factor for improved decision-making. To understand and fully account for the essential user requirements (IFI and client states), engagement with technical leaders is crucial. Fit-for-purpose use of data and comprehensive capacity building eventually ensure scalability and long-term transferability. Future perspectives of EO4SD and DRR regarding mainstreaming are also highlighted.
Making Landsat Time Series Consistent: Evaluating and Improving Landsat Analysis Ready Data
Authors: Qiu Shi , Lin Yukun , Shang Rong , Zhang Junxue , Ma Lei , Zhu Zhe
Published: December 2018

Recently, the United States Geological Survey (USGS) has released a new dataset, called Landsat Analysis Ready Data (ARD), which is designed specifically for facilitating time series analysis. In this study, we evaluated the temporal consistency of this new dataset and recommended several processing streamlines for improving data consistency. Specifically, we examined the impacts of data resampling, cloud/cloud shadow detection, Bidirectional Reflectance Distribution Function (BRDF) correction, and topographic correction on the temporal consistency of the Landsat Time Series (LTS). We have four major observations. First, single-resampled data (ARD) are generally more consistent than double-resampled data (re-projected Collection 1 data), but the difference is very minor. Second, the improved cloud and cloud shadow detection approach (e.g., Fmask 4.0 vs. 3.3) moderately increased data consistency. Third, BRDF correction contributed the most in making LTS consistent. Finally, we corrected the topographic effects by using several widely used algorithms, including Sun-Canopy-Sensor (SCS), a semiempirical SCS (SCS+C), and Illumination Correction (IC) algorithms, however they were found to have very limited or even negative impacts on the consistency of LTS. Therefore, we recommend using Landsat ARD with the improved cloud and cloud shadow detection approach (Fmask 4.0), and with BRDF correction for routine time series analysis.
Crop Classification Based on Temporal Information Using Sentinel-1 SAR Time-Series Data
Authors: Xu Lu , Zhang Hong , Wang Chao , Zhang Bo , Liu Meng
Published: December 2018

With the increasing temporal resolution of space-borne SAR, large amounts of intensity data are now available for continues land observations. Previous researches proved the effectiveness of multitemporal SAR in land classification, but the characterizations of temporal information were still inadequate. In this paper, we proposed a crop classification scheme, which made full use of multitemporal SAR backscattering responses. In this method, the temporal intensity models were established by the K-means clustering method. The intensity vectors were treated as input features, and the mean intensity vectors of cluster centers were regarded as the temporal models. The temporal models summarized the backscatter evolutions of crops and were utilized as the criterion for crop discrimination. The spectral similarity value (SSV) measure was introduced from hyperspectral image processing for temporal model matching. The unlabeled pixel was assigned to the class to which the temporal model with the highest similarity belonged. Two sets of Sentinel-1 SAR time-series data were used to illustrate the effectiveness of the proposed method. The comparison between SSV and other measures demonstrated the superiority of SSV in temporal model matching. Compared with the decision tree (DT) and naive Bayes (NB) classifiers, the proposed method achieved the best overall accuracies in both VH and VV bands. For most crops, it either obtained the best accuracies or achieved comparable accuracies to the best ones, which illustrated the effectiveness of the proposed method.
Assimilating Multiresolution Leaf Area Index of Moso Bamboo Forest from MODIS Time Series Data Based on a Hierarchical Bayesian Network Algorithm
Authors: Xing Luqi , Li Xuejian , Du Huaqiang , Zhou Guomo , Mao Fangjie , Liu Tengyan , Zheng Junlong , Dong Luofan , Zhang Meng , Han Ning , Xu Xiaojun , Fan Weiliang , Zhu Di’en
Published: December 2018

The highly accurate multiresolution leaf area index (LAI) is an important parameter for carbon cycle simulation for bamboo forests at different scales. However, current LAI products have discontinuous resolution with 1 km mostly, that makes it difficult to accurately quantify the spatiotemporal evolution of carbon cycle at different resolutions. Thus, this study used MODIS LAI product (MOD15A2) and MODIS reflectance data (MOD09Q1) of Moso bamboo forest (MBF) from 2015, and it adopted a hierarchical Bayesian network (HBN) algorithm coupled with a dynamic LAI model and the PROSAIL model to obtain high-precision LAI data at multiresolution (i.e., 1000, 500, and 250 m). The results showed the LAIs assimilated using the HBN at the three resolutions corresponded with the actual growth trend of the MBF and correlated significantly with the observed LAI with a determination coefficient (R2) value of >0.80. The highest-precision assimilated LAI was obtained at 1000-m resolution with R2 values of 0.91. The LAI assimilated using the HBN algorithm achieved better accuracy than the MODIS LAI with increases in the R2 value of 2.7 times and decreases in the root mean square error of 87.8%. Therefore, the HBN algorithm applied in this study can effectively obtain highly accurate multiresolution LAI time series data for bamboo forest.
Retrieval of Chlorophyll a from Sentinel-2 MSI Data for the European Union Water Framework Directive Reporting Purposes
Authors: Ansper Ave , Alikas Krista
Published: December 2018

The European Parliament and The Council of the European Union have established the Water Framework Directive (2000/60/EC) for all European Union member states to achieve, at least, “good” ecological status of all water bodies larger than 50 hectares in Europe. The MultiSpectral Instrument onboard European Space Agency satellite Sentinel-2 has suitable 10, 20, 60 m spatial resolution to monitor most of the Estonian lakes as required by the Water Framework Directive. The study aims to analyze the suitability of Sentinel-2 MultiSpectral Instrument data to monitor water quality in inland waters. This consists of testing various atmospheric correction processors to remove the influence of atmosphere and comparing and developing chlorophyll a algorithms to estimate the ecological status of water in Estonian lakes. This study shows that the Sentinel-2 MultiSpectral Instrument is suitable for estimating chlorophyll a in water bodies and tracking the spatial and temporal dynamics in the lakes. However, atmospheric corrections are sensitive to surrounding land and often fail in narrow and small lakes. Due to that, deriving satellite-based chlorophyll a is not possible in every case, but initial results show the Sentinel-2 MultiSpectral Instrument could still provide complementary information to in situ data to support Water Framework Directive monitoring requirements.
Measurement Structures of Image Compressive Sensing for Green Internet of Things (IoT)
Authors: Li Ran , Duan Xiaomeng , Li Yanling
Published: December 2018

Image compressive sensing (CS) is a potential imaging scheme for green internet of things (IoT). To further make CS-based sensor adaptable to low bandwidth and low power, this paper focuses on finding a good measurement structure, i.e., the organization and storage format of CS measurements. Three potential measurement structures are proposed in this paper, respectively raster structure (RA), patch structure, and layer structure (LA). RA stores CS measurements of each column in an image, and PA packets CS measurements of overlapping patches forming an image. LA enables the measuring of small blocks and recovery of large blocks. All of the three structures avoid high computation complexity and huge memory in the process of measuring and recovery, and efficiently suppress the annoying blocking artifacts which often occur in traditional block structures. Experimental results show that RA, PA, and LA can efficiently reduce blocking artifacts, and produce comforting visual qualities. LA, especially, presents both good time-distortion and rate-distortion performance. By this paper, it is proved that LA is a suitable measurement structure for green IoT.
Fog Architectures and Sensor Location Certification in Distributed Event-Based Systems
Authors: Castro-Jul Fátima , Díaz-Redondo Rebeca P. , Fernández-Vilas Ana , Chabridon Sophie , Conan Denis
Published: December 2018

Since smart cities aim at becoming self-monitoring and self-response systems, their deployment relies on close resource monitoring through large-scale urban sensing. The subsequent gathering of massive amounts of data makes essential the development of event-filtering mechanisms that enable the selection of what is relevant and trustworthy. Due to the rise of mobile event producers, location information has become a valuable filtering criterion, as it not only offers extra information on the described event, but also enhances trust in the producer. Implementing mechanisms that validate the quality of location information becomes then imperative. The lack of such strategies in cloud architectures compels the adoption of new communication schemes for Internet of Things (IoT)-based urban services. To serve the demand for location verification in urban event-based systems (DEBS), we have designed three different fog architectures that combine proximity and cloud communication. We have used network simulations with realistic urban traces to prove that the three of them can correctly identify between 73% and 100% of false location claims.
A Time-Varying Filter for Doppler Compensation Applied to Underwater Acoustic OFDM
Authors: Mirhedayati Roudsari Habib , Bousquet Jean-François
Published: December 2018

This paper describes a Doppler compensation algorithm to improve the reliability of orthogonal frequency division multiplexing (OFDM). To compensate for the time-varying Doppler effect in a mobile deployment scenario, first the time-scaling factor over a wideband channel is estimated using pilot tones inserted in each OFDM symbol. Then, using a time-varying resampling technique, the Doppler effect is compensated during the reception of each OFDM symbol in the frame. To predict the performance of the system in relatively shallow waters, a software channel model is developed that is able to simulate a wide variety of dynamic shallow water deployment scenario. The performance of the algorithm was tested for two extreme frequency ranges during sea trials, the first at 2 kHz for a long-range application, and the second at 125 kHz for a short range telemetry link. For the 2-kHz system, a 16-bps mobile link in which the platform was moving at 1 m/s was demonstrated to have a bit error rate on the order of 10 − 3 , while, for the 125-kHz telemetry application, a 2000-bps link was enabled with a bit error rate of 0.03 at a low SNR equal to 5.5 dB.
Robust and Real-Time Detection and Tracking of Moving Objects with Minimum 2D LiDAR Information to Advance Autonomous Cargo Handling in Ports
Authors: Vaquero Victor , Repiso Ely , Sanfeliu Alberto
Published: December 2018

Detecting and tracking moving objects (DATMO) is an essential component for autonomous driving and transportation. In this paper, we present a computationally low-cost and robust DATMO system which uses as input only 2D laser rangefinder (LRF) information. Due to its low requirements both in sensor needs and computation, our DATMO algorithm is meant to be used in current Autonomous Guided Vehicles (AGVs) to improve their reliability for the cargo transportation tasks at port terminals, advancing towards the next generation of fully autonomous transportation vehicles. Our method follows a Detection plus Tracking paradigm. In the detection step we exploit the minimum information of 2D-LRFs by segmenting the elements of the scene in a model-free way and performing a fast object matching to pair segmented elements from two different scans. In this way, we easily recognize dynamic objects and thus reduce consistently by between two and five times the computational burden of the adjacent tracking method. We track the final dynamic objects with an improved Multiple-Hypothesis Tracking (MHT), to which special functions for filtering, confirming, holding, and deleting targets have been included. The full system is evaluated in simulated and real scenarios producing solid results. Specifically, a simulated port environment has been developed to gather realistic data of common autonomous transportation situations such as observing an intersection, joining vehicle platoons, and perceiving overtaking maneuvers. We use different sensor configurations to demonstrate the robustness and adaptability of our approach. We additionally evaluate our system with real data collected in a port terminal the Netherlands. We show that it is able to accomplish the vehicle following task successfully, obtaining a total system recall of more than 98% while running faster than 30 Hz.
General Architecture for Development of Virtual Coaches for Healthy Habits Monitoring and Encouragement
Authors: Benítez-Guijarro Antonio , Ruiz-Zafra Ángel , Callejas Zoraida , Medina-Medina Nuria , Benghazi Kawtar , Noguera Manuel
Published: December 2018

Good health is the result of a healthy lifestyle, where caring about physical activity and nutrition are key concerns. However, in today’s society, nutritional disorders are becoming increasingly frequent, affecting children, adults, and elderly people, mainly due to limited nutrition knowledge and the lack of a healthy lifestyle. A commonly adopted therapy to these imbalances is to monitor physical activity and daily habits, such as recording exercise or creating custom meal plans to count the amount of macronutrients and micronutrients acquired in each meal. Nowadays, many health tracking applications (HTA) have been developed that, for instance, record energy intake as well as users’ physiological parameters, or measure the physical activity during the day. However, most existing HTA do not have a uniform architectural design on top of which to build other applications and services. In this manuscript, we present system architecture intended to serve as a reference architecture for building HTA solutions. In order to validate the proposed architecture, we performed a preliminary evaluation with 15 well recognized experts in systems and software architecture from different entities around world and who have estimated that our proposal can generate architecture for HTA that is adequate, reliable, secure, modifiable, portable, functional, and with high conceptual integrity. In order to show the applicability of the architecture in different HTA, we developed two telemonitoring systems based on it, targeted to different tasks: nutritional coaching (Food4Living) and physical exercise coaching (TrainME). The purpose was to illustrate the kind of end-user monitoring applications that could be developed.
Characterization of a Patch Antenna Sensor’s Resonant Frequency Response in Identifying the Notch-Shaped Cracks on Metal Structure
Authors: Ke Liang , Liu Zhiping , Yu Hanjin
Published: December 2018

Patch antenna sensor is a novel sensor that has great potential in structural health monitoring. The two resonant frequencies of a patch antenna sensor are affected by the crack on its ground plane, which enables it to sense the crack information. This paper presents a detailed characterization of the relationship between the resonant frequencies of a patch antenna sensor and notch-shaped cracks of different parameters, including the length, the orientation, and the center location. After discussing the principle of crack detection using a patch antenna sensor, a parametric study was performed to understand the response of the sensor’s resonant frequencies to various crack configurations. The results show that the crack parameters affect the resonant frequencies in a way that can be represented by the crack’s cutting effect on the sensor’s current flow. Therefore, we introduced a coefficient φ to comprehensively describe this interaction between the crack and the current distribution of the antenna radiation modes. Based on the definition of coefficient φ , an algorithm was proposed for predicting the resonant frequency shifts caused by a random notch-shaped crack and was verified by the experimental measurements. The presented study aims to provide the foundation for the future use of the patch antenna sensor in tracking the propagation of cracks of arbitrary orientation and location in metal structures.
Markov Chain Realization of Multiple Detection Joint Integrated Probabilistic Data Association
Authors: Huang Yuan , Song Taek Lyul , Cheagal Dae Hoon
Published: December 2018

In multiple detection target tracking environments, PDA-based algorithms such as multiple detection joint integrated probabilistic data association (MD-JIPDA) utilize the measurement partition method to generate measurement cells. Thus, one-to-many track-to-measurements associations can be realized. However, in this structure, the number of joint data association events grows exponentially with the number of measurement cells and the number of tracks. MD-JIPDA is plagued by large increases in computational complexity when targets are closely spaced or move cross each other, especially in multiple detection scenarios. Here, the multiple detection Markov chain joint integrated probabilistic data association (MD-MC-JIPDA) is proposed, in which a Markov chain is used to generate random data association sequences. These sequences are substitutes for the association events. The Markov chain process significantly reduces the computational cost since only a few association sequences are generated while keeping preferable tracking performance. Finally, MD-MC-JIPDA is experimentally validated to demonstrate its effectiveness compared with some of the existing multiple detection data association algorithms.
An Untraceable Data Sharing Scheme in Wireless Sensor Networks
Authors: Chen Dong , Lu Wei , Xing Weiwei , Wang Na
Published: December 2018

With the wide application of wireless sensor networks (WSNs), secure data sharing in networks is becoming a hot research topic and attracting more and more attention. A huge challenge is securely transmitting the data from the source node to the sink node. Except for eavesdropping the information stored in the packages, the adversary may also attempt to analyze the contextual information of the network to locate the source node. In this paper, we proposed a secure data sharing approach to defend against the adversary. Specifically, we first design a secret key mechanism to guarantee the security of package delivery between a pair of nodes. Then, a light-weighted secret sharing scheme is designed to map the original message to a set of shares. Finally, the shares are delivered to the sink node independently based on a proper random routing algorithm. Simulation results illustrate that our approach can defend against the eavesdropping and tracing-back attack in an energy-efficient manner.
Cooperation of Voltage Controlled Active Power Filter with Grid-Connected DGs in Microgrid
Authors: Munir Hafiz Mudassir , Zou Jianxiao , Xie Chuan , Guerrero Josep M.
Published: December 2018

Due to the excessive use of nonlinear loads and inverter interfaced distributed generators, harmonic issues have been regarded as a major concern in power distribution systems. Therefore, harmonic compensation in microgrids is a subject of current interest. Consequently, a novel direct harmonic voltage-controlled mode (VCM) active power filter (APF) is proposed to mitigate the harmonics in a cooperative manner and provide a better harmonic compensation performance of less than 5%. Due to the dispersive characteristics of renewable energy resources, voltage feedback based on a harmonic compensation control loop is implemented for the first time. This system can be smoothly combined with the current control loop. Our method proposes a better performance while mitigating the harmonics in comparison with conventional resistive active power filters (R-APF). Based on direct voltage detection at the point of common coupling (PCC), the proposed VCM-APF can therefore be seamlessly incorporated with multiple grid-connected generators (DGs) to enhance their harmonic compensation capabilities. The advantage of this scheme is that it avoids the need for designing and tuning the resistance, which was required in earlier conventional control schemes of R-APF for voltage unbalance compensation. Additionally, our scheme does not require the grid and load current measurements since these can be carried out at the PCC voltage, which further reduces the implementation cost of the system. Furthermore, the simulation results show the significance of proposed method.
Changes in Pre-Service Teachers’ Values, Sense of Agency, Motivation and Consumption Practices: A Case Study of an Education for Sustainability Course
Authors: Merritt Eileen , Hale Annie , Archambault Leanna
Published: December 2018

Teacher education has a critical role to play as people around the world strive to reach the Sustainable Development goals. Education for sustainability (EfS) aims to motivate and prepare educators to create a more sustainable future through education. The purpose of this case study was to explore pre-service teachers’ changes in their values, sense of agency, consumption practices and motivation after participation in a required EfS course. Students were enrolled in a hybrid course that conveyed content through digital stories followed by reflections, in-class discussions and activities. Ninety-one undergraduate students completed pre- and post-course surveys. Students reported significant changes in their beliefs about the relevance of sustainability education, attitudes toward sustainable development, self-efficacy, locus of control and sustainable consumption practices. Qualitative analysis of an open-ended question served to triangulate quantitative findings. Results support the need and potential for EfS courses for educators, particularly in the United States where such courses are not typically required or even offered at most universities.
Range-Gated Imaging System for Underwater Monitoring in Ocean Environment
Authors: Mariani Patrizio , Quincoces Iñaki , Haugholt Karl , Chardard Yves , Visser Andre , Yates Chris , Piccinno Giuliano , Reali Giancarlo , Risholm Petter , Thielemann Jens
Published: December 2018

High-quality video observations are very much needed in underwater environments for the monitoring of several ecosystem indicators and to support the sustainable development and management of almost all activities in the ocean. Reliable video observations are however challenging to collect, because of the generally poor visibility conditions and the difficulties to deploy cost-effective sensors and platforms in the marine environment. Visibility in water is regulated by natural light availability at different depths, and by the presence of suspended particles, scattering incident light in all directions. Those elements are also largely variable in time and space, making it difficult to identify technological solutions that can be used in all conditions. By combining state-of-the-art “time of flight” (ToF) image sensors and innovative pulsed laser illumination, we have developed a range-gated camera system (UTOFIA) that enables affordable and enhanced 3D underwater imaging at high resolution. This range-gated solution allows users to eliminate close-range backscattering, improving quality of the images and providing information on the distance of each illuminated object, hence giving access to real-time 3D measurements. Furthermore, as the system is based on pulsed laser light, it is almost independent of natural light conditions and can achieve similar performances at an extended depth range. We use this system to collect observations in different oceanographic conditions and for different applications, including aquaculture monitoring, seafloor mapping, litter identifications and structure inspection. Performances are evaluated by comparing images to regular cameras and by using standard targets to assess accuracy and precision of distance measurements. We suggest that this type of technology can become a standard in underwater 3D imaging to support the future development of the ocean economy.