bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibacterial-Integrated Collagen Wound Dressing for Diabetes-Related Foot Ulcers: An Evidence-Based Review of Clinical Studies
Authors: N. Amirrah Ibrahim , Mohd Razip Wee Mohd Farhanulhakim , Tabata Yasuhiko , Bt Hj Idrus Ruszymah , Nordin Abid , Fauzi Mh Busra
Published: September 2020

Diabetic foot ulcer (DFU) is a chronic wound frequently delayed from severe infection. Wound dressing provides an essential barrier between the ulcer and the external environment. This review aimed to analyse the effectiveness of antibacterial collagen-based dressing for DFU treatment in a clinical setting. An electronic search in four databases, namely, Scopus, PubMed, Ovid MEDLINE(R), and ISI Web of Science, was performed to obtain relevant articles published within the last ten years. The published studies were included if they reported evidence of (1) collagen-based antibacterial dressing or (2) wound healing for diabetic ulcers, and (3) were written in English. Both randomised and non-randomised clinical trials were included. The search for relevant clinical studies (n) identified eight related references discussing the effectiveness of collagen-based antibacterial wound dressings for DFU comprising collagen impregnated with polyhexamethylene biguanide (n = 2), gentamicin (n = 3), combined-cellulose and silver (n = 1), gentian violet/methylene blue mixed (n = 1), and silver (n = 1). The clinical data were limited by small sample sizes and multiple aetiologies of chronic wounds. The evidence was not robust enough for a conclusive statement, although most of the studies reported positive outcomes for the use of collagen dressings loaded with antibacterial properties for DFU wound healing. This study emphasises the importance of having standardised clinical trials, larger sample sizes, and accurate reporting for reliable statistical evidence confirming DFU treatment efficiency.
Resorcinol-Formaldehyde (RF) as a Novel Plasticizer for Starch-Based Solid Biopolymer Electrolyte
Authors: Selvanathan Vidhya , Ruslan Mohd Hafidz , Aminuzzaman Mohammod , Muhammad Ghulam , Amin N. , Sopian Kamaruzzaman , Akhtaruzzaman Md.
Published: September 2020

A starch-resorcinol-formaldehyde (RF)-lithium triflate (LiTf) based biodegradable polymer electrolyte membrane was synthesized via the solution casting technique. The formation of RF crosslinks in the starch matrix was found to repress the starch’s crystallinity as indicated by the XRD data. Incorporation of the RF plasticizer improved the conductivity greatly, with the highest room-temperature conductivity recorded being 4.29 × 10−4 S cm−1 achieved by the starch:LiTf:RF (20 wt.%:20 wt.%:60 wt.%) composition. The enhancement in ionic conductivity was an implication of the increase in the polymeric amorphous region concurrent with the suppression of the starch’s crystallinity. Chemical complexation between the plasticizer, starch, and lithium salt components in the electrolyte was confirmed by FTIR spectra.
Synthesis of a New Imidazole Amino Acid Ionic Liquid Polymer and Selective Adsorption Performance for Tea Polyphenols
Authors: Luo Yingjie , Huang Xiaoxia , Yao Shun , Peng Lincai , Li Fulin , Song Hang
Published: September 2020

A series of imidazolium ionic liquid monomers with L-Proline anions (ViImCn-L-Pro and (ViIm)2Cn(L-Pro)2) were firstly synthesized, after which new copolymer materials were prepared by polymerization of the ionic liquid monomers with N,N′-methylene diacrylamide (MBA). Polymerization conditions, including the ratio of Ils(ViImCn-L-Pro or (ViIm)2Cn(L-Pro)2) and MBA, solvent, ionic liquids and initiator’s amount, were investigated and found to have an important effect on the adsorption capacity. Polymerization conditions were shown to have more significant impacts on adsorption capacities in the following order: the ratio of Ils and MBA > the amount of initiator > ionic liquids > solvent. The polymers were characterized by IR, EA, SEM, particle size distribution and TG. One of the polymers exhibited the highest selective adsorption capacity of tea polyphenols (521 mg/g). which was significantly higher than other adsorption media. The absorbed tea polyphenols could be desorbed readily with 2% hydrochloric acid methanol solution as eluent. The polymer material could maintain a higher adsorption capacity after four reuses. Based on this polymer, a new method for the efficient separation of tea polyphenols from tea water could be developed.
A Numerical Investigation on Droplet Bag Breakup Behavior of Polymer Solution
Authors: Chu Guidong , Qian Lijuan , Zhong Xiaokai , Zhu Chenlin , Chen Zhongli
Published: September 2020

The deformation and breakup of a polymer solution droplet plays a key role in inkjet printing technology, tablet-coating process, and other spray processes. In this study, the bag breakup behavior of the polymer droplet is investigated numerically. The simple coupled level set and volume of fluid (S-CLSVOF) method and the adaptive mesh refinement (AMR) technique are employed in the droplet breakup cases at different Weber numbers and Ohnesorge numbers. The nature of the polymer solution is handled using Herschel–Bulkley constitutive equations to describe the shear-thinning behavior. Breakup processes, external flow fields, deformation characteristics, energy evolutions, and drag coefficients are analyzed in detail. For the bag breakup of polymer droplets, the liquid bag will form an obvious reticular structure, which is very different from the breakup of a Newtonian fluid. It is found that when the aerodynamic force is dominant, the increase of the droplet viscous force will prolong the breakup time, but has little effect on the final kinetic energy of the droplet. Moreover, considering the large deformation of the droplet in the gas flow, a new formula with the cross-diameter (Dcro) is introduced to modify the droplet drag coefficient.
Development and Evaluation of Superabsorbent Hydrogels Based on Natural Polymers
Authors: Batista Rejane A. , Espitia Paula J. P. , Vergne Daviane M. C. , Vicente António A. , Pereira Paula A. C. , Cerqueira Miguel A. , Teixeira José A. , Jovanovic Jelena , Severino Patricia , Souto Eliana B. , Cardoso Juliana C.
Published: September 2020

Superabsorbent hydrogels (SAHs) are three dimensional networks formed by polymers that can absorb aqueous solution of over 100% of their initial weight. This work aimed to develop and characterize SAHs of Chitosan/Xanthan gum (CG), Chitosan/Alginate (CA) and controlled Chitosan (C), Xanthan gum (G), and Alginate (A) produced using “onion-like” methodology. The swelling performance, the morphological structure, the crystallinity, and the Fourier transformed infrared spectroscopy characteristics of SAH were used for the characterization of polyelectrolytes complex. Swelling analysis showed that chitosan has a strong influence on the maintenance of hydrogels structure after swelling, mainly in the acid environment (pH = 2). The chitosan hydrogel presented around 3000% of acidic fluid absorption after 24 h. The chitosan:xanthan gum (1:1 and 2:1 named as C1G1 and C2G1, respectively) hydrogels were the best combination regarding swelling performance in an acid environment, reaching 1665% and 2024%, respectively, as well at pH 7.0, presenting 1005% (C1G1) and 667% (C2G1). Scanning electron microscopy analysis showed samples with pores, and with different shapes. The X-ray diffraction showed the presence of a characteristic peak at 2θ = 20° in all developed composition because of the crystalline nature of chitosan. This work shows the possibility of developing eco-friendly biopolymer-based SAHs at a low cost with a good swelling capacity and stability.
Platinum-Catalyzed Hydrosilylation in Polymer Chemistry
Authors: Lukin Ruslan Yu. , Kuchkaev Aidar M. , Sukhov Aleksandr V. , Bekmukhamedov Giyjaz E. , Yakhvarov Dmitry G.
Published: September 2020

This paper addresses a review of platinum-based hydrosilylation catalysts. The main field of application of these catalysts is the curing of silicone polymers. Since the 1960s, this area has developed rapidly in connection with the emergence of new polymer compositions and new areas of application. Here we describe general mechanisms of the catalyst activity and the structural effects of the ligands on activity and stability of the catalysts together with the methods for their synthesis.
Grafting with RAFT—gRAFT Strategies to Prepare Hybrid Nanocarriers with Core-shell Architecture
Authors: L. M. Gonçalves José , J. Castanheira Edgar , P. C. Alves Sérgio , Baleizão Carlos , Farinha José Paulo
Published: September 2020

Stimuli-responsive polymer materials are used in smart nanocarriers to provide the stimuli-actuated mechanical and chemical changes that modulate cargo delivery. To take full advantage of the potential of stimuli-responsive polymers for controlled delivery applications, these have been grafted to the surface of mesoporous silica particles (MSNs), which are mechanically robust, have very large surface areas and available pore volumes, uniform and tunable pore sizes and a large diversity of surface functionalization options. Here, we explore the impact of different RAFT-based grafting strategies on the amount of a pH-responsive polymer incorporated in the shell of MSNs. Using a “grafting to” (gRAFT-to) approach we studied the effect of polymer chain size on the amount of polymer in the shell. This was compared with the results obtained with a “grafting from” (gRAFT-from) approach, which yield slightly better polymer incorporation values. These two traditional grafting methods yield relatively limited amounts of polymer incorporation, due to steric hindrance between free chains in “grafting to” and to termination reactions between growing chains in “grafting from.” To increase the amount of polymer in the nanocarrier shell, we developed two strategies to improve the “grafting from” process. In the first, we added a cross-linking agent (gRAFT-cross) to limit the mobility of the growing polymer and thus decrease termination reactions at the MSN surface. On the second, we tested a hybrid grafting process (gRAFT-hybrid) where we added MSNs functionalized with chain transfer agent to the reaction media containing monomer and growing free polymer chains. Our results show that both modifications yield a significative increase in the amount of grafted polymer.
Wall Slip Behaviour of Polymers Based on Molecular Dynamics at the Micro/Nanoscale and Its Effect on Interface Thermal Resistance
Authors: Lou Yan , Wu Gang , Feng Yanfeng
Published: September 2020

Taking the Poiseuille flow of a molten polymer in parallel plates as the research object and polymethyl methacrylate (PMMA) as the research material, an all-atom analysis model of the molecular dynamic flow of polymer macromolecules is established according to the Navier slip law. The effects of wall wettability and external pressure on the wall slip behaviour of polymer macromolecules, as well as the spatial evolution process of the entanglement–unentanglement process of polymer chains near the wall under different shearing effects, were studied. The interface thermal resistance rule was explored, and an interface thermal resistance model considering the wall slip behaviour was established. Finally, a micro-injection experiment was used to verify the validity and accuracy of the model. The results show that when the wall is hydrophobic, the polymer melt exhibits significant wall slip. As the external pressure increases, the wall slip speed and the slip length increase. However, after a certain pressure is exceeded, the growth rate of the slip length is basically zero. As the external pressure increases, the PMMA molecular chains gradually start to separate, the single molecular chain becomes untangled from the entangled grid, and the chain detaches from the wall after exceeding a certain threshold. Wall slip reduces the interface thermal resistance between the solid–liquid interface and enhances the interface heat transfer performance. The interface thermal resistance value calculated by molecular dynamics can more accurately reflect the heat conduction rule of the solid–liquid interface at the micro/nanoscale than that measured by the thermal resistance experiment, indicating that the micro/nano interface thermal resistance obtained by molecular dynamics simulation is reliable.
Influence of Environmental Factors on the Swelling Capacities of Superabsorbent Polymers Used in Concrete
Authors: Jung Andre , Endres Manuel B. , Weichold Oliver
Published: September 2020

Superabsorbent polymers (SAP) are of major interest as materials to control the cement hydration process. The swelling behavior of the SAPs significantly influences the performance of the resulting concrete by slowly releasing polymer-bound water in order to maintain a consistent w/c value. A round-robin test conducted by the RILEM Technical Committee 260-RSC showed that the same batch of polymer can lead to large deviations in concrete performance and this was assumed to originate in different storage conditions of the SAP. In this contribution the change in the performance of two SAPs, a crosslinked poly(acrylate) and a crosslinked poly(acrylate-co-acrylamide), was assessed after ageing in standard climate, at 50 °C, and under UV irradiation. During storage in standard climate or 50 °C, ageing led to dehydration of the SAP, and this subsequently led to a higher water uptake during swelling. By contrast, UV irradiation reduced the water uptake, most likely as a result of photo-crosslinking. Dynamic water vapor sorption experiments indicated a strong dependence of the water uptake on both the ambient humidity and the temperature. As a result, cement mixtures containing SAP must be calculated on the dry mass of the SAP rather than the actual weight on site. A standard procedure of how to pack and handle SAP to be used in concrete is also provided.
Enhanced Intestinal Immune Response in Mice after Oral Administration of Korea Red Ginseng-Derived Polysaccharide
Authors: Park Do Hwi , Han Byungcheol , Shin Myoung-Sook , Hwang Gwi Seo
Published: September 2020

(1) Background: The immunostimulatory role of the polysaccharide fraction (KRG-P) of Korea red ginseng (KRG) was studied in cells. However, its immunomodulatory activity is unknown. Therefore, we investigated the chemical properties of KRG-P and its intestinal immune responses in vitro and in vivo. (2) Methods: KRG-P monosaccharide composition and molecular weight were determined using high-performance liquid and size-exclusion chromatography systems. Immunoglobulin A (IgA) and α-defensin-1 transcript levels were measured using a SYBR Green qRT-PCR; defensin-1, Granulocyte-macrophage colony-stimulating factor (GM-CSF), and IgA protein levels were determined using Western blotting and ELISA kits. (3) Results: The molecular weight of KRG-P was estimated to be 106 kDa, and it contained neutral sugar (74.3%), uronic acid (24.6%), and proteins (1%). In vitro studies of intestinal immunomodulatory activity of KRG-P indicated that GM-CSF and IgA levels increased in Peyer’s patch cells to higher levels than those obtained with KRG and induced bone marrow cell proliferation. In in vivo study, oral KRG-P administration to mice upregulated the expression of α-defensin-1 and IgA in the small intestinal tissue and that of secreted IgA in the feces. (4) Conclusions: KRG-P contributed to the modulation of intestinal immunity and maintenance of intestinal homeostasis against intestinal infection.
Design and Characterization of a Fluidic Device for the Evaluation of SIS-Based Vascular Grafts
Authors: Riveros Alejandra , Cuellar Monica , Sánchez Paolo F. , Muñoz-Camargo Carolina , Cruz Juan C. , Sandoval Néstor , Lopez Mejia Omar D. , Briceño Juan C.
Published: September 2020

Currently available small diameter vascular conduits present several long-term limitations, which has prevented their full clinical implementation. Commercially available vascular grafts show no regenerative capabilities and eventually require surgical replacement; therefore, it is of great interest to develop alternative regenerative vascular grafts (RVG). Decellularized Small Intestinal Submucosa (SIS) is an attractive material for RVG, however, the evaluation of the performance of these grafts is challenging due to the absence of devices that mimic the conditions found in vivo. Thereby, the objective of this study is to design, manufacture and validate in silico and in vitro, a novel fluidic system for the evaluation of human umbilical vein endothelial cells (HUVECs) proliferation on SIS-based RVG under dynamical conditions. Our perfusion and rotational fluidic system was designed in Autodesk Inventor 2018. In silico Computational Fluid Dynamics (CFD) validation of the system was carried out using Ansys Fluent software from ANSYS, Inc for dynamical conditions of a pulsatile pressure function measured experimentally over a rigid wall model. Mechanical and biological parameters such as flow regime, pressure gradient, wall shear stress (WSS), sterility and indirect cell viability (MTT assay) were also evaluated. Cell adhesion was confirmed by SEM imaging. The fluid flow regime within the system remains laminar. The system maintained sterility and showed low cytotoxicity levels. HUVECs were successfully cultured on SIS-based RVG under both perfusion and rotation conditions. In silico analysis agreed well with our experimental and theoretical results, and with recent in vitro and in vivo reports for WSS. The system presented is a tool for evaluating RVG and represents an alternative to develop new methods and protocols for a more comprehensive study of regenerative cardiovascular devices.
Hydrothermal Carbonization of Olive Tree Pruning as a Sustainable Way for Improving Biomass Energy Potential: Effect of Reaction Parameters on Fuel Properties
Authors: González-Arias Judith , Sánchez Marta Elena , Martínez Elia Judith , Covalski Camila , Alonso-Simón Ana , González Rubén , Cara-Jiménez Jorge
Published: September 2020

Hydrothermal carbonization (HTC) allows the conversion of organic waste into a solid product called hydrochar with improved fuel properties. Olive tree pruning biomass (OTP), a very abundant residue in Mediterranean countries, was treated by HTC to obtain a solid fuel similar to coal that could be used in co-combustion processes. Three different reaction temperatures (220, 250, and 280 °C) and reaction times (3, 6, and 9 h) were selected. The hydrochars obtained were extensively analyzed to study their behavior as fuel (i.e., ultimate, proximate, fiber and thermogravimetric analysis, Fourier-transform infrared spectroscopy (FTIR), activation energy, and combustion performance). The concentrations of cellulose, hemicellulose, and lignin in the samples depict a clear and consistent trend with the chemical reactions carried out in this treatment. Regarding O/C and H/C ratios and HHV, the hydrochars generated at more severe conditions are similar to lignite coal, reaching values of HHV up to 29.6 MJ kg−1. The higher stability of the solid is reflected by the increase of the activation energy (≈60 kJ mol−1), and ignition temperatures close to 400 °C. With this, HTC is a proper thermal treatment for the management of raw OTP biomass and its further conversion into a solid biofuel.
Improvement of Energy Efficiency and Productivity in an Electric Arc Furnace through the Modification of Side-Wall Injector Systems
Authors: Sung Yonmo , Lee Sangyoun , Han Kyungmoon , Koo Jaduck , Lee Seongjae , Jang Doyoung , Oh Changyong , Jang Byunghwa
Published: September 2020

The energy cost of producing steel in an electric arc furnace (EAF) has a sizable influence on the prices of natural gas and electricity. Therefore, it is important to use these energies efficiently via a tailored oxy-fuel combustion burner and oxygen lance. In this study, an important modification of the side-wall injector system in the EAF at Hyundai Steel Incheon works was implemented to reduce electrical energy consumption and improve productivity. A protruding water-cooled copper jacket, including a newly designed burner, was developed to reduce the distance between the jet nozzle and the molten steel. In addition, the jet angles for the burner and lance were separately set for each scrap melting and refining mode. The modifications led to a reduction in electrical energy consumption of 5 kWh/t and an increase in productivity of approximately 3.1 t/h. Consequently, total energy cost savings of 0.3 USD/t and a corresponding annual cost savings of approximately 224,000 USD/year were achieved.
Joint Use of Spaceborne Microwave Sensor Data and CYGNSS Data to Observe Tropical Cyclones
Authors: Wang Shiwei , Shi Shuzhu , Ni Binbin
Published: September 2020

The joint use of spaceborne microwave sensor data and Cyclone Global Navigation Satellite System (CYGNSS) data to observe tropical cyclones (TCs) is presented in this paper. The Soil Moisture Active and Passive (SMAP) radiometer was taken as an example of a spaceborne microwave sensor, and its data and the CYGNSS data were fused to fix the center of a TC and to measure the maximum wind speed around the TC inner core. This process included data preprocessing, image fusion, determination of the TC center position, and the estimation of the TC’s intensity. For all of the observed hurricanes, the experimental results demonstrated that the proposed method obtains a more complete structure of the TC and can measure the surface wind speed around the TC inner core at more frequent intervals compared to the case where the SMAP radiometer data or the CYGNSS data are employed alone. Furthermore, when comparing the TC tracks obtained by the proposed method with the best tracks provided by the National Hurricane Center (NHC), we found that the mean absolute error values ranged between 18.4 and 46 km, the standard deviation varied between 15.1 and 28.2 km, and both of these were smaller than the values obtained by only using the CYGNSS data. In addition, when comparing the maximum wind speed around the TC inner core obtained by the proposed method with the best track peak winds estimated by the NHC, we found that the mean absolute error values ranged between 7.7 and 15.7 m/s, the root-mean-square difference values varied between 8.6 and 18 m/s, the correlation coefficients varied between 0.1782 and 0.9877, the bias values varied between −8.5 and 4.5 m/s, and all of these values were smaller in most cases, than those obtained by only using the CYGNSS data.
3D Reconstruction of a Complex Grid Structure Combining UAS Images and Deep Learning
Authors: Knyaz Vladimir A. , Kniaz Vladimir V. , Remondino Fabio , Zheltov Sergey Y. , Gruen Armin
Published: September 2020

The latest advances in technical characteristics of unmanned aerial systems (UAS) and their onboard sensors opened the way for smart flying vehicles exploiting new application areas and allowing to perform missions seemed to be impossible before. One of these complicated tasks is the 3D reconstruction and monitoring of large-size, complex, grid-like structures as radio or television towers. Although image-based 3D survey contains a lot of visual and geometrical information useful for making preliminary conclusions on construction health, standard photogrammetric processing fails to perform dense and robust 3D reconstruction of complex large-size mesh structures. The main problem of such objects is repeated and self-occlusive similar elements resulting in false feature matching. This paper presents a method developed for an accurate Multi-View Stereo (MVS) dense 3D reconstruction of the Shukhov Radio Tower in Moscow (Russia) based on UAS photogrammetric survey. A key element for the successful image-based 3D reconstruction is the developed WireNetV2 neural network model for robust automatic semantic segmentation of wire structures. The proposed neural network provides high matching quality due to an accurate masking of the tower elements. The main contributions of the paper are: (1) a deep learning WireNetV2 convolutional neural network model that outperforms the state-of-the-art results of semantic segmentation on a dataset containing images of grid structures of complicated topology with repeated elements, holes, self-occlusions, thus providing robust grid structure masking and, as a result, accurate 3D reconstruction, (2) an advanced image-based pipeline aided by a neural network for the accurate 3D reconstruction of the large-size and complex grid structured, evaluated on UAS imagery of Shukhov radio tower in Moscow.
Calibration of Industrial Cameras for Aerial Photogrammetric Mapping
Authors: Kolecki Jakub , Kuras Przemysław , Pastucha Elżbieta , Pyka Krystian , Sierka Maciej
Published: September 2020

This paper details the development of a camera calibration method purpose-built for use in photogrammetric survey production. The calibration test field was established in a hangar, where marker coordinates were measured using a high-precision survey methodology guaranteeing very high accuracy. An analytical model for bundle adjustment was developed that does not directly use the coordinates of field calibration markers but integrates bundle adjustment and survey observations into a single process. This solution, as well as a classical calibration method, were implemented in a custom software, for which the C++ source code repository is provided. The method was tested using three industrial cameras. The comparison was drawn towards a baseline method, OpenCV implementation. The results point to the advantages of using the proposed approach utilizing extended bundle adjustment.
LDAP: Lightweight Dynamic Auto-Reconfigurable Protocol in an IoT-Enabled WSN for Wide-Area Remote Monitoring
Authors: Rahman Gazi M. E. , Wahid Khan A.
Published: September 2020

IoT (Internet of Things)-based remote monitoring and controlling applications are increasing in dimensions and domains day by day. Sensor-based remote monitoring using a Wireless Sensor Network (WSN) becomes challenging for applications when both temporal and spatial data from widely spread sources are acquired in real time. In applications such as environmental, agricultural, and water quality monitoring, the data sources are geographically distributed, and have little or no cellular connectivity. These applications require long-distance wireless or satellite connections for IoT connectivity. Present WSNs are better suited for densely populated applications and require a large number of sensor nodes and base stations for wider coverage but at the cost of added complexity in routing and network organization. As a result, real time data acquisition using an IoT connected WSN is a challenge in terms of coverage, network lifetime, and wireless connectivity. This paper proposes a lightweight, dynamic, and auto-reconfigurable communication protocol (LDAP) for Wide-Area Remote Monitoring (WARM) applications. It has a mobile data sink for wider WSN coverage, and auto-reconfiguration capability to cope with the dynamic network topology required for device mobility. The WSN coverage and lifetime are further improved by using a Long-Range (LoRa) wireless interface. We evaluated the performance of the proposed LDAP in the field in terms of the data delivery rate, Received Signal Strength (RSS), and Signal to Noise Ratio (SNR). All experiments were conducted in a field trial for a water quality monitoring application as a case study. We have used both static and mobile data sinks with static sensor nodes in an IoT-connected environment. The experimental results show a significant reduction (up to 80%) of the number of data sinks while using the proposed LDAP. We also evaluated the energy consumption to determine the lifetime of the WSN using the LDAP algorithm.
A Vector Operation to Extract Second-Order Terrain Derivatives from Digital Elevation Models
Authors: Hu Guanghui , Dai Wen , Li Sijin , Xiong Liyang , Tang Guoan
Published: September 2020

Terrain derivatives exhibit surface morphology in various aspects. However, existing spatial change calculation methods for terrain derivatives are based on a mathematical scalar operating system, which may disregard the directional property of the original data to a certain extent. This situation is particularly true in second-order terrain derivatives, in which original data can be terrain derivatives with clear directional properties, such as slope or aspect. Thus, this study proposes a mathematical vector operation method for the calculation of second-order terrain derivatives. Given the examples of the first-order terrain derivatives of slope and aspect, their second-order terrain derivatives are calculated using the proposed vector method. Directional properties are considered and vectorized using the following steps: rotation-type judgment, standardization of initial direction, and vector representation. The proposed vector method is applied to one mathematical Gaussian surface and three different ground landform areas using digital elevation models (DEMs) with 5 and 1 m resolutions. Comparison analysis results between the vector and scalar methods show that the former achieves more reasonable and accurate second-order terrain derivatives than the latter. Moreover, the vector method avoids overexpression or even exaggeration errors. This vector operation concept and its expanded methods can be applied in calculating other terrain derivatives in geomorphometry.
A Near Real-Time Method for Forest Change Detection Based on a Structural Time Series Model and the Kalman Filter
Authors: Puhm Martin , Deutscher Janik , Hirschmugl Manuela , Wimmer Andreas , Schmitt Ursula , Schardt Mathias
Published: September 2020

The increasing availability of dense time series of earth observation data has incited a growing interest in time series analysis for vegetation monitoring and change detection. Vegetation monitoring algorithms need to deal with several time series characteristics such as seasonality, irregular sampling intervals, and signal artefacts. While common algorithms based on deterministic harmonic regression models account for intra-annual seasonality, inter-annual variations of the seasonal pattern related to shifts in vegetation phenology due to different temperature and rainfall are usually not accounted for. We propose a transition to stochastic modelling and present a near real-time change detection method that combines a structural time series model with the Kalman filter. The model continuously adapts to new observations and allows to better separate phenology-related deviations from vegetation anomalies or land cover changes. The method is tested in a forest change detection application aiming at the assessment of damages caused by storm events and insect calamities. Forest changes are detected based on the cumulative sum control chart (CUSUM) which is used to decide if new observations deviate from model-based forecasts. The performance is evaluated in two test sites, one in Malawi (dry tropical forest) and one in Austria (temperate deciduous, coniferous and mixed forests) based on Sentinel-2 time series. Both forest areas are characterized by a distinct, but temporally varying leaf-off season. The presented change detection method shows overall accuracies above 99%, users’ accuracies of 76.8% to 88.6%, and producers’ accuracies of 68.2% to 80.4% for the forest change stratum (minimum mapping unit: 0.1 ha). Results are based on visually interpreted points derived by stratified random sampling. A further analysis revealed that increasing the time series density by merging data from two Sentinel-2 orbits yields better forest change detection accuracies in comparison to using data from one orbit only. The resulting increase in users’ accuracy amounts to 7.6%. The presented method is capable of near real-time processing and could be used for a variety of automated forest monitoring applications.
Applications of Remote Sensing in Precision Agriculture: A Review
Authors: Sishodia Rajendra P. , Ray Ram L. , Singh Sudhir K.
Published: September 2020

Agriculture provides for the most basic needs of humankind: food and fiber. The introduction of new farming techniques in the past century (e.g., during the Green Revolution) has helped agriculture keep pace with growing demands for food and other agricultural products. However, further increases in food demand, a growing population, and rising income levels are likely to put additional strain on natural resources. With growing recognition of the negative impacts of agriculture on the environment, new techniques and approaches should be able to meet future food demands while maintaining or reducing the environmental footprint of agriculture. Emerging technologies, such as geospatial technologies, Internet of Things (IoT), Big Data analysis, and artificial intelligence (AI), could be utilized to make informed management decisions aimed to increase crop production. Precision agriculture (PA) entails the application of a suite of such technologies to optimize agricultural inputs to increase agricultural production and reduce input losses. Use of remote sensing technologies for PA has increased rapidly during the past few decades. The unprecedented availability of high resolution (spatial, spectral and temporal) satellite images has promoted the use of remote sensing in many PA applications, including crop monitoring, irrigation management, nutrient application, disease and pest management, and yield prediction. In this paper, we provide an overview of remote sensing systems, techniques, and vegetation indices along with their recent (2015–2020) applications in PA. Remote-sensing-based PA technologies such as variable fertilizer rate application technology in Green Seeker and Crop Circle have already been incorporated in commercial agriculture. Use of unmanned aerial vehicles (UAVs) has increased tremendously during the last decade due to their cost-effectiveness and flexibility in obtaining the high-resolution (cm-scale) images needed for PA applications. At the same time, the availability of a large amount of satellite data has prompted researchers to explore advanced data storage and processing techniques such as cloud computing and machine learning. Given the complexity of image processing and the amount of technical knowledge and expertise needed, it is critical to explore and develop a simple yet reliable workflow for the real-time application of remote sensing in PA. Development of accurate yet easy to use, user-friendly systems is likely to result in broader adoption of remote sensing technologies in commercial and non-commercial PA applications.
Stereo Dense Image Matching by Adaptive Fusion of Multiple-Window Matching Results
Authors: Han Yilong , Liu Wei , Huang Xu , Wang Shugen , Qin Rongjun
Published: September 2020

Traditional stereo dense image matching (DIM) methods normally predefine a fixed window to compute matching cost, while their performances are limited by the matching window sizes. A large matching window usually achieves robust matching results in weak-textured regions, while it may cause over-smoothness problems in disparity jumps and fine structures. A small window can recover sharp boundaries and fine structures, while it contains high matching uncertainties in weak-textured regions. To address the issue above, we respectively compute matching results with different matching window sizes and then proposes an adaptive fusion method of these matching results so that a better matching result can be generated. The core algorithm designs a Convolutional Neural Network (CNN) to predict the probabilities of large and small windows for each pixel and then refines these probabilities by imposing a global energy function. A compromised solution of the global energy function is utilized by breaking the optimization into sub-optimizations of each pixel in one-dimensional (1D) paths. Finally, the matching results of large and small windows are fused by taking the refined probabilities as weights for more accurate matching. We test our method on aerial image datasets, satellite image datasets, and Middlebury benchmark with different matching cost metrics. Experiments show that our proposed adaptive fusion of multiple-window matching results method has a good transferability across different datasets and outperforms the small windows, the median windows, the large windows, and some state-of-the-art matching window selection methods.
Land Use/Land Cover Changes and Their Driving Factors in the Northeastern Tibetan Plateau Based on Geographical Detectors and Google Earth Engine: A Case Study in Gannan Prefecture
Authors: Liu Chenli , Li Wenlong , Zhu Gaofeng , Zhou Huakun , Yan Hepiao , Xue Pengfei
Published: September 2020

As an important production base for livestock and a unique ecological zone in China, the northeast Tibetan Plateau has experienced dramatic land use/land cover (LULC) changes with increasing human activities and continuous climate change. However, extensive cloud cover limits the ability of optical remote sensing satellites to monitor accurately LULC changes in this area. To overcome this problem in LULC mapping in the Ganan Prefecture, 2000–2018, we used the dense time stacking of multi-temporal Landsat images and random forest algorithm based on the Google Earth Engine (GEE) platform. The dynamic trends of LULC changes were analyzed, and geographical detectors quantitatively evaluated the key driving factors of these changes. The results showed that (1) the overall classification accuracy varied between 89.14% and 91.41%, and the kappa values were greater than 86.55%, indicating that the classification results were reliably accurate. (2) The major LULC types in the study area were grassland and forest, and their area accounted for 50% and 25%, respectively. During the study period, the grassland area decreased, while the area of forest land and construction land increased to varying degrees. The land-use intensity presents multi-level intensity, and it was higher in the northeast than that in the southwest. (3) Elevation and population density were the major driving factors of LULC changes, and economic development has also significantly affected LULC. These findings revealed the main factors driving LULC changes in Gannan Prefecture and provided a reference for assisting in the development of sustainable land management and ecological protection policy decisions.
Study of the Influence of Phase Noise on the MEMS Disk Resonator Gyroscope Interface Circuit
Authors: Zhang Wenbo , Chen Weiping , Yin Liang , Di Xinpeng , Chen Dongliang , Fu Qiang , Zhang Yufeng , Liu Xiaowei
Published: September 2020

In this paper, a detailed analysis of the influence of phase noise on the micro-electro-mechanical system (MEMS) disk resonator gyroscope (DRG) is presented. Firstly, a new time-varying phase noise model for the gyroscope is established, which explains how the drive loop circuit noise converts into phase noise. Different from previous works, the time-varying phase noise model in this paper is established in mechanical domain, which gain more physical insight into the origin of the phase noise in gyroscope. Furthermore, the impact of phase noise on DRG is derived, which shows how the phase noise affects angular velocity measurement. The analysis shows that, in MEMS DRG, the phase noise, together with other non-ideal factors such as direct excitation of secondary resonator, may cause a low frequency noise in the output of the gyroscope system and affect the bias stability of the gyroscope. Finally, numerical simulations and experiment tests are designed to prove the theories above.
WSN-Assisted UAV Trajectory Adjustment for Pesticide Drift Control
Authors: Hu Jie , Wang Tuan , Yang Jiacheng , Lan Yubin , Lv Shilei , Zhang Yali
Published: September 2020

Unmanned Aerial Vehicles (UAVs) have been widely applied for pesticide spraying as they have high efficiency and operational flexibility. However, the pesticide droplet drift caused by wind may decrease the pesticide spraying efficiency and pollute the environment. A precision spraying system based on an airborne meteorological monitoring platform on manned agricultural aircrafts is not adaptable for. So far, there is no better solution for controlling droplet drift outside the target area caused by wind, especially by wind gusts. In this regard, a UAV trajectory adjustment system based on Wireless Sensor Network (WSN) for pesticide drift control was proposed in this research. By collecting data from ground WSN, the UAV utilizes the wind speed and wind direction as inputs to autonomously adjust its trajectory for keeping droplet deposition in the target spraying area. Two optimized algorithms, namely deep reinforcement learning and particle swarm optimization, were applied to generate the newly modified flight route. At the same time, a simplified pesticide droplet drift model that includes wind speed and wind direction as parameters was developed and adopted to simulate and compute the drift distance of pesticide droplets. Moreover, an LSTM-based wind speed prediction model and a RNN-based wind direction prediction model were established, so as to address the problem of missing the latest wind data caused by communication latency or a lack of connection with the ground nodes. Finally, experiments were carried out to test the communication latency between UAV and ground WSN, and to evaluate the proposed scheme with embedded Raspberry Pi boards in UAV for feasibility verification. Results show that the WSN-assisted UAV trajectory adjustment system is capable of providing a better performance of on-target droplet deposition for real time pesticide spraying with UAV.
A New Long-Term Marine Biodiversity Monitoring Program for the Knowledge and Management in Marine Protected Areas of the Mexican Caribbean
Authors: Perera-Valderrama Susana , Cerdeira-Estrada Sergio , Martell-Dubois Raúl , Rosique-de la Cruz Laura , Caballero-Aragón Hansel , Valdez-Chavarin Jaime , López-Perea José , Ressl Rainer
Published: September 2020

In the Mexican Caribbean, 15 marine protected areas (MPAs) have been established for managing and protecting marine ecosystems. These MPAs receive high anthropogenic pressure from coastal development, tourism, and fishing, all in synergy with climate change. To contribute to the MPAs’ effectiveness, it is necessary to provide a long-term observation system of the condition of marine ecosystems and species. Our study proposes the establishment of a new marine biodiversity monitoring program (MBMP) focusing on three MPAs of the Mexican Caribbean. Five conservation objects (COs) were defined (coral reefs, seagrass beds, mangroves, marine turtles, and sharks-rays) for their ecological relevance and the pressures they are facing. Coral reef, seagrass and mangroves have multiple biological, biogeochemical and physical interactions. Marine turtles are listed as endangered species, and the status of their populations is unknown in the marine area of the MPAs. Elasmobranchs play a key role as top and medium predators, and their populations have been poorly studied. Indicators were proposed for monitoring each CO. As a technological innovation, all information obtained from the MBMP will be uploaded to the Coastal Marine Information and Analysis System (SIMAR), a public, user-friendly and interactive web platform that allows for automatic data management and processing.
Automotive Aftermarket Forecast in a Changing World: The Stakeholders’ Perceptions Boost!
Authors: Laborda Juan , Moral María José
Published: September 2020

This study presents a methodology for forecasting the medium– and long–term real revenues of the automotive post–sales service sectors, assuming the automobile industry is nowadays undergoing a deep process of transformation. There are several conditioning factors, usage as well as environmental reasons, that makes past times an unreasonable guide for a future forecast. Firstly, we estimate, using regression models, the most important variables for the automobile sector that will affect the long–term forecasts of the automotive aftermarket’s revenues. Secondly, we apply participatory methods to quantify the impact of the new conditioning factors. This is a research tool used for the Spanish automotive aftermarket. Our results indicate how stakeholders’ perceptions modulate the forecasts for those economic sectors involved in a disrupted changing business model.
Analysis of the Patent of a Protective Cover for Vertical-Axis Wind Turbines (VAWTs): Simulations of Wind Flow
Authors: Moleón Baca Jose Alberto , Expósito González Antonio Jesús , Gutiérrez Montes Candido
Published: September 2020

This paper presents a numerical and experimental analysis of the patent of a device to be used in vertical-axis wind turbines (VAWTs) under extreme wind conditions. The device consists of two hemispheres interconnected by a set of conveniently implemented variable section ducts through which the wind circulates to the blades. Furthermore, the design of the cross-section of the ducts allows the control of the wind speed inside the device. These ducts are intended to work as diffusers or nozzles, depending on the needs of the installation site. Simulations were performed for the case of high-speed external wind, for which the ducts act as diffusers to reduce wind speed and maintain a well-functioning internal turbine. Four different patent designs were analyzed, focusing on turbine performance and generated power. The results indicate that the patent allows the generation of electric power for a greater range of wind speeds than with a normal wind turbine. The results support that this patent may be a good alternative for wind power generation in geographic areas with extreme weather conditions or with maintained or strong gusty wind. Experimental tests were carried out on the movement of the blades using the available model. Finally, the power curve of the model of this wind turbine was obtained.
Corporate Foundations as Partnership Brokers in Supporting the United Nations’ Sustainable Development Goals (SDGs)
Authors: Gehringer Theresa
Published: September 2020

Rather than limiting themselves to acting as mere financial intermediaries of corporate philanthropic funds, corporate foundations (CFs) may contribute to the achievement of the Sustainable Development Goals (SDGs) as partnership brokers. Based on the literature on the SDGs, cross-sector partnerships, the influence of the private sector on the SDGs, and institutional philanthropic involvement in the SDGs, this paper shows how the unique characteristics of CFs and their position between the business sector and civil society make them ideal partnership brokers in cross-sector collaborations. Furthermore, this study examines how CFs approach the Agenda 2030 with respect to their activities and strategies. Following an explorative research approach, data were collected through an online survey among CF managers in Switzerland, Liechtenstein, and Germany. The findings suggest that, in order to contribute more effectively to the SDGs, CFs should make more and better use of their capacities in bridging institutional logics, pooling resources, and initiating partnerships between different sectors.