bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Canopy Height and Bud Light Exposure on the Early Stages of Flower Development in Prunus persica (L.) Batsch
Authors: Peavey Madeleine , Goodwin Ian , McClymont Lexie
Published: August 2020

The aims of this study were to investigate the sunlight requirements during floral initiation and differentiation for the development of flower buds in ‘Autumn Bright’ nectarine and to explore its source–sink relationship. In early January 2019 (111 days after full bloom), prior to floral initiation and differentiation, 12 new shoots were tagged on 14 trees, with four shoots in each of the low (0–1.2 m), middle (1.2–2.0 m), and high (>2.0 m) canopy heights. Three treatments (bud shading; leaf pluck; bud shading and leaf pluck) were applied to three shoots in each canopy height on the fourth and eighth bud, in addition to a fourth control shoot. Light penetration was measured at the different canopy heights. Buds were assessed in Spring for floral transition, number of floral buds per node, and fruit set. The treatments at the node level had no effect on floral initiation, indicating that sink strength was not promoted by additional light. Light penetration decreased with decreasing canopy height and corresponded with lower floral buds in the low zone. Fruit set was uninfluenced by all treatments. The results of this study emphasised the importance of the availability of photosynthetic assimilates for floral initiation in peach and nectarine trees. Balanced crop load management and summer pruning to enhance canopy sunlight distribution would increase the availability of nutrients for improved floral transition in this cultivar.
Turkish Propolis and Its Nano Form Can Ameliorate the Side Effects of Cisplatin, Which Is a Widely Used Drug in the Treatment of Cancer
Authors: Tatli Seven Pinar , Seven Ismail , Karakus Selcan , Iflazoglu Mutlu Seda , Arkali Gozde , Muge Sahin Yesim , Kilislioglu Ayben
Published: August 2020

This study was performed to determine the effects of chitosan-coated nano-propolis (NP), which is synthesized via a green sonochemical method, and propolis on the side effects of cisplatin (CP), which is a widely used drug in the treatment of cancer. For this aim, 56 rats were divided into seven groups, balancing their body weights (BW). The study was designed as Control, CP (3 mg/kg BW at single dose of CP as intraperitoneal, ip), Propolis (100 mg/kg BW per day of propolis by gavage), NP-10 (10 mg/kg BW of NP per day by gavage), CP + Propolis (3 mg/kg BW of CP and 100 mg/kg BW of propolis), CP + NP-10 (3 mg/kg CP and 10 mg/kg BW of NP), and CP + NP-30 (3 mg/kg BW of CP and 30 mg/kg BW of NP). Propolis and NP (especially NP-30) were preserved via biochemical parameters, oxidative stress, and activation of apoptotic pathways (anti-apoptotic protein: Bcl-2 and pro-apoptotic protein: Bax) in liver and kidney tissues in the toxicity induced by CP. The NP were more effective than propolis at a dose of 30 mg/kg BW and had the potential to ameliorate CP’s negative effects while overcoming serious side effects such as liver and kidney damage.
Comparative Metabolomics Profiling of Polyphenols, Nutrients and Antioxidant Activities of Two Red Onion (Allium cepa L.) Cultivars
Authors: Metrani Rita , Singh Jashbir , Acharya Pratibha , K. Jayaprakasha Guddadarangavvanahally , S. Patil Bhimanagouda
Published: August 2020

Onion is among the most widely cultivated and consumed economic crops. Onions are an excellent dietary source of polyphenols and nutrients. However, onions phytonutrient compositions vary with cultivars and growing locations. Therefore, the present study involved the evaluation of polyphenol, nutritional composition (proteins, nitrogen, and minerals), sugars, pyruvate, antioxidant, and α-amylase inhibition activities of red onion cultivars, sweet Italian, and honeysuckle grown in California and Texas, respectively. The total flavonoid for honeysuckle and sweet Italian was 449 and 345 μg/g FW, respectively. The total anthocyanin for honeysuckle onion was 103 μg/g FW, while for sweet Italian onion was 86 μg/g FW. Cyanidin-3-(6”-malonoylglucoside) and cyanidin-3-(6”-malonoyl-laminaribioside) were the major components in both the cultivars. The pungency of red onions in honeysuckle ranged between 4.9 and 7.9 μmoL/mL, whereas in sweet Italian onion ranged from 8.3 to 10 μmoL/mL. The principal component analysis was applied to determine the most important variables that separate the cultivars of red onion. Overall results indicated that total flavonoids, total phenolic content, total anthocyanins, protein, and calories for honeysuckle onions were higher than the sweet Italian onions. These results could provide information about high quality and adding value to functional food due to the phytochemicals and nutritional composition of red onions.
Ion Acceleration in Multi-Fluid Plasma: Including Charge Separation Induced Electric Field Effects in Supersonic Wave Layers
Authors: Burrows Ross
Published: August 2020

The need to understand the process by which particles, including solar wind and coronal ions as well as pickup ions, are accelerated to high energies (ultimately to become anomalous cosmic rays) motivate a multi-fluid shock wave model which includes kinetic effects (e.g., ion acceleration) in an electromagnetically self-consistent framework. Particle reflection at the cross-shock potential leads to ion acceleration in the motional electric field and thus anisotropic heating and pressure in the shock layer, with important consequences for the multi-fluid dynamics. This motivates development of a multi-fluid model of solar wind electrons and ions treated as fluid, coupled self-consistently with a small population of ions (e.g., pickup ions) dynamically treated as individual particles. Consideration of both the time dependent and steady state regimes, indicate that such a multi-fluid approach is necessary for resolving the, Debye scale, particle reflecting cross-shock potential and subsequent dynamics. To study charge separation effects in narrow, supersonic wave layers we consider a reduction of the system to the steady state for cold ions and hot electrons and find two types of solitary waves inherent to the reduced two-fluid system in this limiting case.
Ameliorated Performance of Sulfonated Poly(Arylene Ether Sulfone) Block Copolymers with Increased Hydrophilic Oligomer Ratio in Proton-Exchange Membrane Fuel Cells Operating at 80% Relative Humidity
Authors: Kim Ae , Vinothkannan Mohanraj , Lee Kyu , Chu Ji , Ryu Sumg , Kim Hwan , Lee Jae-Young , Lee Hong-Ki , Yoo Dong
Published: August 2020

We designed and synthesized a series of sulfonated poly(arylene ether sulfone) (SPES) with different hydrophilic or hydrophobic oligomer ratios using poly-condensation strategy. Afterward, we fabricated the corresponding membranes via a solution-casting approach. We verified the SPES membrane chemical structure using nuclear magnetic resonance (1H NMR) and confirmed the resulting oligomer ratio. Field-emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM) results revealed that we effectively attained phase separation of the SPES membrane along with an increased hydrophilic oligomer ratio. Thermal stability, glass transition temperature (Tg) and membrane elongation increased with the ratio of hydrophilic oligomers. SPES membranes with higher hydrophilic oligomer ratios exhibited superior water uptake, ion-exchange capacity, contact angle and water sorption, while retaining reasonable swelling degree. The proton conductivity results showed that SPES containing higher amounts of hydrophilic oligomers provided a 74.7 mS cm−1 proton conductivity at 90 °C, which is better than other SPES membranes, but slightly lower than that of Nafion-117 membrane. When integrating SPES membranes with proton-exchange membrane fuel cells (PEMFCs) at 60 °C and 80% relative humidity (RH), the PEMFC power density exhibited a similar increment-pattern like proton conductivity pattern.
Novel On-Demand 3-Dimensional (3-D) Printed Tablets Using Fill Density as an Effective Release-Controlling Tool
Authors: Thakkar Rishi , Pillai Amit Raviraj , Zhang Jiaxiang , Zhang Yu , Kulkarni Vineet , Maniruzzaman Mohammed
Published: August 2020

This research demonstrates the use of fill density as an effective tool for controlling the drug release without changing the formulation composition. The merger of hot-melt extrusion (HME) with fused deposition modeling (FDM)-based 3-dimensional (3-D) printing processes over the last decade has directed pharmaceutical research towards the possibility of printing personalized medication. One key aspect of printing patient-specific dosage forms is controlling the release dynamics based on the patient’s needs. The purpose of this research was to understand the impact of fill density and interrelate it with the release of a poorly water-soluble, weakly acidic, active pharmaceutical ingredient (API) from a hydroxypropyl methylcellulose acetate succinate (HPMC-AS) matrix, both mathematically and experimentally. Amorphous solid dispersions (ASDs) of ibuprofen with three grades of AquaSolveTM HPMC-AS (HG, MG, and LG) were developed using an HME process and evaluated using solid-state characterization techniques. Differential scanning calorimetry (DSC), powder X-ray diffraction (pXRD), and polarized light microscopy (PLM) confirmed the amorphous state of the drug in both polymeric filaments and 3D printed tablets. The suitability of the manufactured filaments for FDM processes was investigated using texture analysis (TA) which showed robust mechanical properties of the developed filament compositions. Using FDM, tablets with different fill densities (20–80%) and identical dimensions were printed for each polymer. In vitro pH shift dissolution studies revealed that the fill density has a significant impact (F(11, 24) = 15,271.147, p < 0.0001) and a strong negative correlation (r > −0.99; p < 0.0001) with the release performance, where 20% infill demonstrated the fastest and most complete release, whereas 80% infill depicted a more controlled release. The results obtained from this research can be used to develop a robust formulation strategy to control the drug release from 3D printed dosage forms as a function of fill density.
The Influence of the Accelerated Aging Conditions on the Properties of Polyolefin Geogrids Used for Landfill Slope Reinforcement
Authors: Kiersnowska Agnieszka , Fabianowski Wojciech , Koda Eugeniusz
Published: August 2020

Polyolefin geosynthetics are susceptible to oxidative degradation, which in turn leads to diminished mechanical properties in geotechnical constructions. When using these materials, it is extremely important to determine their durability over time in particularly aggressive conditions. In order to prolong the life of a geosynthetic material, antioxidants are added during the manufacturing process. The function of antioxidants is to prevent polymer oxidation reaction in time. As the antioxidant content is depleted, the polymer becomes less protected towards oxidative attacks. This article describes the aging process of uniaxial (high density polyethylene) HDPE geogrids under the influence of chemical and environmental factors. Evaluations of accelerated aging test of the uniaxial HDPE geogrids were incubated in simulated landfill conditions for a period of 12 months. Three temperatures (25 °C, 45 °C, and 75 °C) were selected for carrying out the aging experiments in aqueous solutions mimicking landfill conditions. The changes observed by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and melt flow index (MFI) correlate with the mechanical properties of the aged geogrid. No significant changes in the FTIR and MFI were observed over the 12 months of accelerated aging tests at none of the three different temperatures. The oxidation induction time (OIT) test showed no antioxidant remaining in the geogrid following eight months of aging test at 75 °C. No significant changes in the influence of accelerated aging tests on the average relative elongation at 25 °C and 45 °C of the tested material were observed. Accelerated aging tests at 75 °C showed that the mean elongation of 12.12% for the sample not subjected to accelerated aging tests (new sample) increased to 19.32% (after 12 months of incubation).
MPPE/SEBS Composites with Low Dielectric Loss for High-Frequency Copper Clad Laminates Applications
Authors: Guo Jianming , Wang Hao , Zhang Caixia , Zhang Qilong , Yang Hui
Published: August 2020

Copper clad laminates (CCLs) with low dissipation factor (Df) are urgently needed in the fields of high-frequency communications devices. A novel resin matrix of modified poly (2,6-dimethyl-1,4-phenylene ether) (MPPE) and styrene-ethylene/butylene-styrene (SEBS) was employed in the fabrication of high-frequency copper clad laminates (CCLs). The composites were reinforced by E-glass fabrics, which were modified with phenyltriethoxysilane (PhTES). The composite laminates obtained exhibited impressive dielectric loss of 0.0027 at 10 GHz when the weight ratio of MPPE to SEBS was 5:1. In order to modify the dielectric constant (Dk), coefficient of thermal expansion (CTE) and other performances of laminates, Li2TiO3 (LT) ceramic powders were introduced into the resin matrix. The composite laminates showed low dielectric loss of 0.0026 at 10 GHz and relatively high flexural strength of 125 MPa when the mass ratio of LT fillers to resin is 0.4. Moreover, the composite laminates all maintain low water uptake (<0.5%). The microstructure and thermal properties of composite laminates filled with LT ceramic powders were also tested. These results show that copper clad laminates prepared with modified polyphenylene ether (MPPE)/SEBS and LT ceramic fillers have strong competitiveness to fabricate printed circuit boards (PCBs) for high-frequency and high-speed applications.
Extending Cellulose-Based Polymers Application in Additive Manufacturing Technology: A Review of Recent Approaches
Authors: Mohan Denesh , Teong Zee Khai , Bakir Afifah Nabilah , Sajab Mohd Shaiful , Kaco Hatika
Published: August 2020

The materials for additive manufacturing (AM) technology have grown substantially over the last few years to fulfill industrial needs. Despite that, the use of bio-based composites for improved mechanical properties and biodegradation is still not fully explored. This limits the universal expansion of AM-fabricated products due to the incompatibility of the products made from petroleum-derived resources. The development of naturally-derived polymers for AM materials is promising with the increasing number of studies in recent years owing to their biodegradation and biocompatibility. Cellulose is the most abundant biopolymer that possesses many favorable properties to be incorporated into AM materials, which have been continuously focused on in recent years. This critical review discusses the development of AM technologies and materials, cellulose-based polymers, cellulose-based three-dimensional (3D) printing filaments, liquid deposition modeling of cellulose, and four-dimensional (4D) printing of cellulose-based materials. Cellulose-based AM material applications and the limitations with future developments are also reviewed.
Controlled Release, Disintegration, Antioxidant, and Antimicrobial Properties of Poly (Lactic Acid)/Thymol/Nanoclay Composites
Authors: Ramos Marina , Fortunati Elena , Beltrán Ana , Peltzer Mercedes , Cristofaro Francesco , Visai Livia , Valente Artur J.M. , Jiménez Alfonso , Kenny José María , Garrigós María Carmen
Published: August 2020

Nano-biocomposite films based on poly (lactic acid) (PLA) were prepared by adding thymol (8 wt.%) and a commercial montmorillonite (D43B) at different concentrations (2.5 and 5 wt.%). The antioxidant, antimicrobial, and disintegration properties of all films were determined. A kinetic study was carried out to evaluate the thymol release from the polymer matrix into ethanol 10% (v/v) as food simulant. The nanostructured networks formed in binary and ternary systems were of interest in controlling the release of thymol into the food simulant. The results indicated that the diffusion of thymol through the PLA matrix was influenced by the presence of the nanoclay. Disintegration tests demonstrated that the incorporation of both additives promoted the breakdown of the polymer matrix due to the presence of the reactive hydroxyl group in the thymol structure and ammonium groups in D43B. Active films containing thymol and D43B efficiently enhanced the antioxidant activity (inhibition values higher than 77%) of the nano-biocomposites. Finally, the addition of 8 wt.% thymol and 2.5 wt.% D43B significantly increased the antibacterial activity against Escherichia coli and Staphylococcus aureus 8325-4, resulting in a clear advantage to improve the shelf-life of perishable packaged food.
Temperature Behavior of Aqueous Solutions of Poly(2-Oxazoline) Homopolymer and Block Copolymers Investigated by NMR Spectroscopy and Dynamic Light Scattering
Authors: Konefał Rafał , Černoch Peter , Konefał Magdalena , Spěváček Jiří
Published: August 2020

1H NMR methods in combination with dynamic light scattering were applied to study temperature behavior of poly(2-isopropyl-2-oxazoline) (PIPOx) homopolymer as well as PIPOx-b-poly(2-methyl-2-oxazoline) (PMeOx) and poly(2-ethyl-2-oxazoline) (PEtOx)-b-PMeOx diblock copolymers in aqueous solutions. 1H NMR spectra showed a different way of phase transition for the main and side chains in PIPOx-based solutions. Additionally, the phase transition is irreversible for PIPOx homopolymer and partially reversible for PIPOx-b-PMeOx copolymer. As revealed by NMR, the phase transition in PEtOx-based copolymers solutions exists despite the absence of solution turbidity. It is very broad, virtually independent of the copolymer composition and reversible with some hysteresis. Two types of water molecules were detected in solutions of the diblock copolymers above the phase transition—“free” with long and “bound” with short spin–spin relaxation times T2. NOESY spectra revealed information about conformational changes observed already in the pre-transition region of PIPOx-b-PMeOx copolymer solution.
Synthesis of New Cyclodextrin-Based Adsorbents to Remove Direct Red 83:1
Authors: Pellicer José A. , Rodríguez-López María Isabel , Fortea María Isabel , Gómez-López Vicente M. , Auñón David , Núñez-Delicado Estrella , Gabaldón José A.
Published: August 2020

Two cyclodextrins (CDs), γ– and hydroxypropyl (HP)–γ–CDs were used to synthesize new adsorbents by using epichlorohydrin (EPI) as cross-linking agent in order to remove Direct Red 83:1 (DR) from water. Both polymers were characterized in terms of Fourier spectroscopy, nuclear magnetic resonance, particle size distribution and thermogravimetric analysis. Experimental data for both polymers were well fitted to the pseudo-second order and intraparticle diffusion model, indicating that in the adsorption both chemical and physical interactions are essential in the removal of DR. Three different isotherm models were analyzed, concluding that γ–CDs–EPI followed the Temkin isotherm and HP–γ–CDs-EPI the Freundlich isotherm, these results suggested that the adsorption was happening onto heterogeneous surfaces. The results of the Gibbs free energy showed that the adsorption was spontaneous at room temperature. In order to eliminate the remaining dye after the polymer treatment, and advanced oxidation process (AOP) was considered, achieving more than 90% of removal combining both mechanisms.
Glycerol Oxidation over Supported Gold Catalysts: The Combined Effect of Au Particle Size and Basicity of Support
Authors: Pakrieva Ekaterina , Kolobova Ekaterina , German Dmitrii , Stucchi Marta , Villa Alberto , Prati Laura , Carabineiro Sónia. A.C. , Bogdanchikova Nina , Cortés Corberán Vicente , Pestryakov Alexey
Published: August 2020

Gold nanoparticles supported on various oxides (CeO2, CeO2/TiO2, MgO, MgO/TiO2, La2O3, La2O3/TiO2) (with 4 wt.% Au loading) were investigated in the liquid (aqueous) phase oxidation of glycerol by molecular oxygen under mild conditions, in the presence of alkaline earth (CaO, SrO and MgO) or alkaline (NaOH) bases. Full conversion and selectivity between 38 and 68% to sodium glycerate were observed on different Au supported catalysts (Au/MgO/TiO2, Au/La2O3/TiO2, Au/CeO2 and Au/CeO2/TiO2). The combined effect of Au particle size and basicity of the support was suggested as the determining factor of the activity. Agglomeration of gold nanoparticles, found after the reaction, led to the deactivation of the catalysts, which prevents the further oxidation of sodium glycerate into sodium tartronate. Promising results were obtained with the use of alkaline earth bases (CaO, SrO, MgO), leading to the formation of free carboxylic acids instead of salts, which are formed in the presence of the more usual base, NaOH.
Performance Analysis and Working Fluid Selection for Single and Two Stages Vapor Compression Refrigeration Cycles
Authors: Saleh Bahaa , Aly Ayman A. , Alsehli Mishal , Elfasakhany Ashraf , Bassuoni Mohamed M.
Published: August 2020

Screening for alternative refrigerants with high energy efficiency and low environmental impacts is one of the highest challenges of the refrigeration sector. This paper investigates the performance and refrigerant screening for single and two stages vapor compression refrigeration cycles. Several pure hydrocarbons, hydrofluorocarbons, hydrofluoroolefins, fluorinated ethers, and binary azeotropic mixtures are proposed as alternative refrigerants to substitute R22 and R134a due to their environmental impacts. The BACKONE equation of state is used to compute the thermodynamic properties of the candidates. The results show that the maximum coefficients of performance (COP) for single and two stage cycles using pure substances are achieved using cyclopentane with values of 4.14 and 4.35, respectively. On the other side, the maximum COP for the two cycles using azeotropic mixtures is accomplished using R134a + RE170 with values of 3.96 and 4.27, respectively. The two-stage cycle presents gain in COP between 5.1% and 19.6% compared with the single-stage cycle based on the used refrigerant. From the obtained results, among all investigated refrigerants, cyclopentane is the most suitable refrigerant for the two cycles from the viewpoint of energy efficiency. However, extra cautions should be taken due to its flammability.
Souvenirs and the Commodification of Sámi Spirituality in Tourism
Authors: Mathisen Stein R.
Published: August 2020

Tangible, material objects sold in tourism contexts are often seen as problematic examples of commercialization, especially when they are marketed as examples of intangible Indigenous cultural heritages, representing Indigenous religion or spirituality. Taking the in situ presentations of examples of Sámi souvenirs connected to religious contexts in souvenir shops as a point of departure, this analysis investigates the complex relations these elements enter, with reference to religion, to the past, to the arts or crafts field, and to questions of ownership. The main theoretical focus is on how these souvenirs are adjusted to general, Western tourism imaginaries. One of the examples of such souvenirs are replicas in different sizes and qualities of the Sámi noaidi’s drum, while other examples discuss the use of the symbols on the drum applied to souvenir products, such as jewelry or other design products. Points of departure are the material souvenirs themselves, contextualized with in situ presentations in shops, on the net, and in social media, and linked to tourism imaginaries. The article tries to show how this in turn is related to still prevailing, general Western understandings of Indigenous Sámi religion and spiritualty.
Religion-Making in the Disney Feature Film, Frozen II: Indigenous Religion and Dynamics of Agency
Authors: Fonneland Trude
Published: August 2020

This paper explores the religion-making potential of a particular secular institution, namely the Walt Disney Studios. Focusing on the animation film Frozen II that was launched in November 2019, the current article enters into debates about the manner in which indigenous religion is part of the commodity presented—how religion is produced, packaged, and staged. In the article I argue that contemporary media-scapes can be seen as agents of religion-making, of religious circulation, and renewal. As such, religion, as it is expressed in Frozen II, is outlined and produced by a particular media-form and shaped as a popular cultural formation. Further discussions about cultural appropriation are highlighted, focusing on how Disney’s reach out for cooperation with the Sámi community can generate new cultural policies and practices.
Changes in the Environmental Sustainability of the Urban Transport System when Introducing Paid Parking for Private Vehicles
Authors: Zakharov Dmitrii , Fadyushin Alexey , Chainikov Denis
Published: August 2020

The work proposes a methodological approach to studying and assessing the environmental sustainability of the transport system of the city. The authors have selected parameters for assessing the environmental sustainability of the transport system and identified significant factors affecting environmental sustainability. A coefficient of environmental sustainability of the urban transport system and a formula for its calculation are proposed. A simulation was used to assess the amount of emissions of harmful substances from the car exhaust gases if the demand structure changes with respect to the means of transport and transportation methods. The paper presents the results of changing the parameters of the traffic flow and demand by means of transport and transportation methods when introducing a parking fee in the central part of the city, changing the cost of parking and expanding the paid parking area.
Classifying Intelligence in Machines: A Taxonomy of Intelligent Control
Authors: Wilson Callum , Marchetti Francesco , Di Carlo Marilena , Riccardi Annalisa , Minisci Edmondo
Published: August 2020

The quest to create machines that can solve problems as humans do leads us to intelligent control. This field encompasses control systems that can adapt to changes and learn to improve their actions—traits typically associated with human intelligence. In this work we seek to determine how intelligent these classes of control systems are by quantifying their level of adaptability and learning. First we describe the stages of development towards intelligent control and present a definition based on literature. Based on the key elements of this definition, we propose a novel taxonomy of intelligent control methods, which assesses the extent to which they handle uncertainties in three areas: the environment, the controller, and the goals. This taxonomy is applicable to a variety of robotic and other autonomous systems, which we demonstrate through several examples of intelligent control methods and their classifications. Looking at the spread of classifications based on this taxonomy can help researchers identify where control systems can be made more intelligent.
OLCI A/B Tandem Phase Analysis, Part 2: Benefits of Sensors Harmonisation for Level 2 Products
Authors: Lamquin Nicolas , Déru Alexis , Clerc Sébastien , Bourg Ludovic , Donlon Craig
Published: August 2020

This study is a follow-up of a full methodology for the homogenisation and harmonisation of the two Ocean and Land Colour Instrument (OLCI) payloads based on the tandem phase analysis. Sentinel-3B was manoeuvred into a tandem configuration with its operational twin Sentinel-3A already in orbit few weeks after its launch, which was followed by a short drift phase during which Sentinel-3B was progressively moved to a specific orbit phasing of 140° separation from the sentinel-3A. Harmonisation is performed at Level 1 for the radiometric alignment of the OLCI-A TOA radiances to the ones of OLCI-B, considering the slight spectral differences between the two instruments. The benefits of this harmonisation for the main Level 2 products are assessed in the present manuscript for both land and water products. The results validate such benefits showing accuracy between the two sensors after harmonisation better than the products requirements specifications. For the water processing branch, this accuracy opens a path toward an ensemble Sentinel-3 system vicarious calibration with ground-truth measurements. For land products, the tandem phase analysis is also an opportunity to demonstrate that the terrestrial chlorophyll index product requires improvements of the preliminary spectral adjustment of the red-edge channel at 709 nm. As comparisons from the measurements acquired over the tandem phase provides confidence in the alignment of the OLCI-A and OLCI-B series of products, preliminary analysis of the measurements acquired over the drift phase provides the first insights into the sensitivity of the processing algorithms to the geometry of acquisition as well as to calibration residuals of the OLCI field-of-view. As the harmonisation currently performs a radiometric alignment of OLCI-A to OLCI-B, the question of the reference sensor for operational implementation of the harmonisation raises concerns on the individual quality of the calibration of each sensor, notably their across-track consistency. Following the investigations performed at Level 1, where relatively strong calibration residuals are shown between the OLCI cameras and very similarly for both instruments; we discuss the impact of these residuals at L2 using an empirical correction and further conclude with the need to address these problematics with more attention in the future. We conclude with the extreme usefulness of the tandem phase analysis, presently for Level 2 products, and the need to further monitor the temporal stability of the cross-calibration of the OLCI payloads with a view to implementing their harmonisation at operational level.
Recent Changes in Water Discharge in Snow and Glacier Melt-Dominated Rivers in the Tienshan Mountains, Central Asia
Authors: Zhang Qifei , Chen Yaning , Li Zhi , Fang Gonghuan , Xiang Yanyun , Li Yupeng , Ji Huiping
Published: August 2020

Global warming has generally led to changes in river runoffs fed by snow and glacier meltwater in mountain ranges. The runoff of the Aksu River, which originates in the Southern Tienshan Mountains, exhibited a positive trend during 1979–2002, but this trend reversed during 2002–2015. Through a comprehensive analysis, this study aims to estimate potential reasons for changes in the runoff of its two contrasting headwaters: the Toxkan and Kumalak Rivers, based on climatic data, the altitude of the 0 °C isotherm, glacier mass balance (GMB), snow cover area (SCA), snow depth (SD) and the sensitivity model. For the Toxkan River, the decrease in spring runoff mainly resulted from reductions in precipitation, whereas the decrease in summer runoff was mainly caused by early snowmelt in spring and a much-reduced snow meltwater supply in summer. In addition, the obvious glacier area reduction in the catchment (decreased to less than 4%) also contributed to the reduced summer runoff. For the Kumalak River, a sharp decrease rate of 10.21 × 108 m3/decade in runoff was detected due to summertime cooling of both surface and upper air temperatures. Reduced summer temperatures with a positive trend in precipitation not only inhibited glacier melting but also dropped the 0 °C layer altitude, resulting in a significant increase in summertime SCA and SD, a slowing of the glacier negative mass balance, and a lowering of the snow-line altitude.
Automated Processing for Flood Area Detection Using ALOS-2 and Hydrodynamic Simulation Data
Authors: Ohki Masato , Yamamoto Kosuke , Tadono Takeo , Yoshimura Kei
Published: August 2020

Rapid and frequent mapping of flood areas are essential for monitoring and mitigating flood disasters. The Advanced Land Observing Satellite-2 (ALOS-2) carries an L-band synthetic aperture radar (SAR) capable of rapid and frequent disaster observations. In this study, we developed a fully automatic, fast computation, and robust method for detecting flood areas using ALOS-2 and hydrodynamic flood simulation data. This study is the first attempt to combine flood simulation data from the Today’s Earth system (TE) with SAR-based disaster mapping. We used Bayesian inference to combine the amplitude/coherence data by ALOS-2 and the flood fraction data by TE. Our experimental results used 12 flood observation sets of data from Japan and had high accuracy and robustness for use under various ALOS-2 observation conditions. Flood simulation contributed to improving the accuracy of flood detection and reducing computation time. Based on these findings, we also assessed the operability of our method and found that the combination of ALOS-2 and TE data with our analysis method was capable of daily flood monitoring.
The Determination of Effective Beamwidth of Ku Band Profiling Radar Based on Waveform Matching Method in the Boreal Forest of Finland
Authors: Zhou Hui , Chen Yuwei , Hu Nan , Dong Yuandan , Xu Xinmin , Feng Ziyi , Hakala Teemu , Hyyppä Juha
Published: August 2020

Radar scientists typically define the radar beamwidth as a half-power beamwidth (HPBW) in the main lobe of the antenna pattern. However, the microwave radiations outside radar HPBW might also backscatter into the radar receiver and change the distribution of the received signal. To determine an actual and effective beamwidth illuminated on the measured targets, we first generate the simulated-waveforms derived from coincident lidar points and radar equation and then develop a waveform matching method to seek out an optimal beamwidth based on the 95% threshold of correlation coefficients between radar waveforms and the simulated-waveforms. The 8565 measurements of a Ku-band profiling radar named Tomoradar and coincident lidar data in a widespread heterogeneous forest area of southern Finland are employed for resolving the effective beamwidth. The results reveal that about 97% of the effective beamwidth are larger than Tomoradar HPBW, but the effective beamwidth could be changeable for each measurement due to variations in the scattering properties of vegetation. Thus, a fixed average effective beamwidth (AEBW) with 0.1-degree resolution is introduced to determine Tomoradar cone according to the effective beamwidth and corresponding proportions. We discover that Tomoradar AEBW is approximately approaching to 8°, which is larger than Tomoradar HPBW of 6°. If we regard AEBW as the actual Tomoradar beamwidth rather than HPBW, the simulated-waveforms have substantially stronger correlation strength with Tomoradar waveforms, and canopy tops derived from lidar data within Tomoradar AEBW are much closer to those extracted from Tomoradar waveforms. The results demonstrate that radar AEBW is a more appropriate reference for designing radar antenna and selecting the region size of validation data such as lidar points or the ground truth. However, considering that radar AEBW is variable for different radar antenna pattern, we suggest that actual radar beamwidth should be defined with a fraction of total radiation energy within radar AEBW, just like the definition of laser divergence of lidar based on the percentage of transmitted laser energy. In this paper, for a forest inventory research case, the fraction of total radiation energy within the AEBW for radar system is supposed to be 91%.
Spatiotemporal Variation of Surface Urban Heat Islands in Relation to Land Cover Composition and Configuration: A Multi-Scale Case Study of Xi’an, China
Authors: Lu Linlin , Weng Qihao , Xiao Da , Guo Huadong , Li Qingting , Hui Wenhua
Published: August 2020

Urban heat islands (UHI) can lead to multiple adverse impacts, including increased air pollution, morbidity, and energy consumption. The association between UHI effects and land cover characteristics has been extensively studied but is insufficiently understood in inland cities due to their unique urban environments. This study sought to investigate the spatiotemporal variations of the thermal environment and their relationships with land cover composition and configuration in Xi’an, the largest city in northwestern China. Land cover maps were classified and land surface temperature (LST) was estimated using Landsat imagery in six time periods from 1995 to 2020. The variations of surface heat island were captured using multi-temporal LST data and a surface urban heat island intensity (SUHII) indicator. The relationship between land cover features and land surface temperature was analyzed through multi-resolution grids and correlation analysis. The results showed that mean SUHII in the study area increased from 0.683 °C in 1995 to 2.759 °C in 2020. The densities of impervious surfaces had a stronger impact on LST than green space, with Pearson’s correlation coefficient r ranging from 0.59 to 0.97. The correlation between normalized difference impervious surface index and LST was enhanced with the enlargement of the grid cell size. The correlations between normalized difference vegetation index and LST reached maxima and stabilized at grid cell sizes of 210 and 240 m. Increasing the total area and aggregation level of urban green space alleviated the negative impacts of UHI in the study area. Our results also highlight the necessity of multi-scale analysis for examining the relationships between landscape configuration metrics and LST. These findings improved our understanding of the spatiotemporal variation of the surface urban heat island effect and its relationship with land cover features in a major inland city of China.
High Sensitivity Microfiber Interferometer Sensor in Aqueous Solution
Authors: Girei Saad Hayatu , Lim Hong Ngee , Ahmad Muhammad Zamharir , Mahdi Mohd Adzir , Md Zain Ahmad Rifqi , Yaacob Mohd Hanif
Published: August 2020

The need for environmental protection and water pollution control has led to the development of different sensors for determining many kinds of pollutants in water. Ammonia nitrogen presence is an important indicator of water quality in environmental monitoring applications. In this paper, a high sensitivity sensor for monitoring ammonia nitrogen concentration in water using a tapered microfiber interferometer (MFI) as a sensor platform and a broad supercontinuum laser as the light source is realized. The MFI is fabricated to the waist diameter of 8 µm producing a strong interference pattern due to the coupling of the fundamental mode with the cladding mode. The MFI sensor is investigated for a low concentration of ammonia nitrogen in water in the wide wavelength range from 1500–1800 nm with a high-power signal provided by the supercontinuum source. The broad source allows optical sensing characteristics of the MFI to be evaluated at four different wavelengths (1505, 1605, 1705, and 1785 nm) upon exposure towards various ammonia nitrogen concentrations. The highest sensitivity of 0.099 nm/ppm that indicates the wavelength shift is observed at 1785 nm operating wavelength. The response is linear in the ammonia nitrogen range of 5–30 ppm with the best measurement resolution calculated to be 0.5 ppm. The low concentration ammonia nitrogen detected by the MFI in the unique infrared region reveals the potential application of this optical fiber-based sensor for rivers and drinking water monitoring.
QA-kNN: Indoor Localization Based on Quartile Analysis and the kNN Classifier for Wireless Networks
Authors: Ferreira David , Souza Richard , Carvalho Celso
Published: August 2020

Considering the variation of the received signal strength indicator (RSSI) in wireless networks, the objective of this study is to investigate and propose a method of indoor localization in order to improve the accuracy of localization that is compromised by RSSI variation. For this, quartile analysis is used for data pre-processing and the k-nearest neighbors (kNN) classifier is used for localization. In addition to the tests in a real environment, simulations were performed, varying many parameters related to the proposed method and the environment. In the real environment with reference points of 1.284 density per unit area (RPs/m2), the method presents zero-mean error in the localization in test points (TPs) coinciding with the RPs. In the simulated environment with a density of 0.327 RPs/m2, a mean error of 0.490 m for the localization of random TPs was achieved. These results are important contributions and allow us to conclude that the method is promising for locating objects in indoor environments.
A Capacitive Feedback Transimpedance Amplifier with a DC Feedback Loop Using a Transistor for High DC Dynamic Range
Authors: Noh Jung-hoon
Published: August 2020

This study proposes a capacitive feedback transimpedance amplifier (CF-TIA) using a transistor in the direct current (DC) feedback loop for high DC dynamic range. In some applications, the background DC input can vary widely from the minimum to the maximum, and TIA have to sense the target signal even on the top of the maximum DC input. In a conventional CF-TIA, however, the allowable DC input is constrained by the value of the resistor in the DC feedback loop. To allow a fairly high DC input, the resistor is set to a very low value. This causes the thermal noise current to increase significantly. The increased thermal noise is always present even in the minimum DC input, thus degrading the overall noise performance. The circuit proposed herein overcomes this shortcoming by using the transistor instead of the resistor. The adverse effect of the parasitic capacitance of the transistor on system stability is compensated for as well. Then, the analyses of the overall frequency response and design parameters, including the cut-off frequency and attenuation ratio associated with system stability, are presented for the proposed circuit. In addition, in order to cope with the problem that stability is dependent on the amount of DC input, a simple method for ensuring system stability regardless of DC component value is introduced. The presented analyses and the method are generalized for all CF-TIA applications.
Low Dimensional Discriminative Representation of Fully Connected Layer Features Using Extended LargeVis Method for High-Resolution Remote Sensing Image Retrieval
Authors: Zhuo Zheng , Zhou Zhong
Published: August 2020

Recently, there have been rapid advances in high-resolution remote sensing image retrieval, which plays an important role in remote sensing data management and utilization. For content-based remote sensing image retrieval, low-dimensional, representative and discriminative features are essential to ensure good retrieval accuracy and speed. Dimensionality reduction is one of the important solutions to improve the quality of features in image retrieval, in which LargeVis is an effective algorithm specifically designed for Big Data visualization. Here, an extended LargeVis (E-LargeVis) dimensionality reduction method for high-resolution remote sensing image retrieval is proposed. This can realize the dimensionality reduction of single high-dimensional data by modeling the implicit mapping relationship between LargeVis high-dimensional data and low-dimensional data with support vector regression. An effective high-resolution remote sensing image retrieval method is proposed to obtain stronger representative and discriminative deep features. First, the fully connected layer features are extracted using a channel attention-based ResNet50 as a backbone network. Then, E-LargeVis is used to reduce the dimensionality of the fully connected features to obtain a low-dimensional discriminative representation. Finally, L2 distance is computed for similarity measurement to realize the retrieval of high-resolution remote sensing images. The experimental results on four high-resolution remote sensing image datasets, including UCM, RS19, RSSCN7, and AID, show that for various convolutional neural network architectures, the proposed E-LargeVis can effectively improve retrieval performance, far exceeding other dimensionality reduction methods.
A Secure and Lightweight Fine-Grained Data Sharing Scheme for Mobile Cloud Computing
Authors: Li Haifeng , Lan Caihui , Fu Xingbing , Wang Caifen , Li Fagen , Guo He
Published: August 2020

With the explosion of various mobile devices and the tremendous advancement in cloud computing technology, mobile devices have been seamlessly integrated with the premium powerful cloud computing known as an innovation paradigm named Mobile Cloud Computing (MCC) to facilitate the mobile users in storing, computing and sharing their data with others. Meanwhile, Attribute Based Encryption (ABE) has been envisioned as one of the most promising cryptographic primitives for providing secure and flexible fine-grained “one to many” access control, particularly in large scale distributed system with unknown participators. However, most existing ABE schemes are not suitable for MCC because they involve expensive pairing operations which pose a formidable challenge for resource-constrained mobile devices, thus greatly delaying the widespread popularity of MCC. To this end, in this paper, we propose a secure and lightweight fine-grained data sharing scheme (SLFG-DSS) for a mobile cloud computing scenario to outsource the majority of time-consuming operations from the resource-constrained mobile devices to the resource-rich cloud servers. Different from the current schemes, our novel scheme can enjoy the following promising merits simultaneously: (1) Supporting verifiable outsourced decryption, i.e., the mobile user can ensure the validity of the transformed ciphertext returned from the cloud server; (2) resisting decryption key exposure, i.e., our proposed scheme can outsource decryption for intensive computing tasks during the decryption phase without revealing the user’s data or decryption key; (3) achieving a CCA security level; thus, our novel scheme can be applied to the scenarios with higher security level requirement. The concrete security proof and performance analysis illustrate that our novel scheme is proven secure and suitable for the mobile cloud computing environment.
Selecting the Best Image Pairs to Measure Slope Deformation
Authors: Yang Wentao
Published: August 2020

Optical remote sensing images can be used to monitor slope deformation in mountain regions. Abundant optical sensors onboard various platforms were designed to provide increasingly high spatial–temporal resolution images at low cost; however, finding the best image pairs to derive slope deformation remains difficult. By selecting a location in the east Tibetan Plateau, this work used the co-registration of optically sensed images and correlation (COSI-Corr) method to analyze 402 Sentinel-2 images from August 2015 to February 2020, to quantify temporal patterns of uncertainty in deriving slope deformation. By excluding 66% of the Sentinel-2 images that were contaminated by unfavorable weather, uncertainties were found to fluctuate annually, with the least uncertainty achieved in image pairs of similar dates in different years. Six image pairs with the least uncertainties were selected to derive ground displacement for a moving slope in the study area. Cross-checks among these image pairs showed consistent results, with uncertainties less than 1/10 pixels in length. The findings from this work could help in the selection of the best image pairs to derive reliable slope displacement from large numbers of optical images.