Latest Articles

Open AccessArticle
Performance Evaluation for China’s Planned CO2-IPDA
Remote Sens. 2017, 9(8), 768; doi:10.3390/rs9080768 (registering DOI) -
Abstract
Active remote sensing of atmospheric XCO2 has several advantages over existing passive remote sensors, including global coverage, a smaller footprint, improved penetration of aerosols, and night observation capabilities. China is planning to launch a multi-functional atmospheric observation satellite equipped with a CO
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Active remote sensing of atmospheric XCO2 has several advantages over existing passive remote sensors, including global coverage, a smaller footprint, improved penetration of aerosols, and night observation capabilities. China is planning to launch a multi-functional atmospheric observation satellite equipped with a CO2-IPDA (integrated path differential absorption Lidar) to measure columnar concentrations of atmospheric CO2 globally. As space and power are limited on the satellite, compromises have been made to accommodate other passive sensors. In this study, we evaluated the sensitivity of the system’s retrieval accuracy and precision to some critical parameters to determine whether the current configuration is adequate to obtain the desired results and whether any further compromises are possible. We then mapped the distribution of random errors across China and surrounding regions using pseudo-observations to explore the performance of the planned CO2-IPDA over these regions. We found that random errors of less than 0.3% can be expected for most regions of our study area, which will allow the provision of valuable data that will help researchers gain a deeper insight into carbon cycle processes and accurately estimate carbon uptake and emissions. However, in the areas where major anthropogenic carbon sources are located, and in coastal seas, random errors as high as 0.5% are predicted. This is predominantly due to the high concentrations of aerosols, which cause serious attenuation of returned signals. Novel retrieving methods must, therefore, be developed in the future to suppress interference from low surface reflectance and high aerosol loading. Full article
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Open AccessArticle
Gauging the Severity of the 2012 Midwestern U.S. Drought for Agriculture
Remote Sens. 2017, 9(8), 767; doi:10.3390/rs9080767 (registering DOI) -
Abstract
Different drought indices often provide different diagnoses of drought severity, making it difficult to determine the best way to evaluate these different drought monitoring results. Additionally, the ability of a newly proposed drought index, the Process-based Accumulated Drought Index (PADI) has not yet
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Different drought indices often provide different diagnoses of drought severity, making it difficult to determine the best way to evaluate these different drought monitoring results. Additionally, the ability of a newly proposed drought index, the Process-based Accumulated Drought Index (PADI) has not yet been tested in United States. In this study, we quantified the severity of 2012 drought which affected the agricultural output for much of the Midwestern US. We used several popular drought indices, including the Standardized Precipitation Index and Standardized Precipitation Evapotranspiration Index with multiple time scales, Palmer Drought Severity Index, Palmer Z-index, VegDRI, and PADI by comparing the spatial distribution, temporal evolution, and crop impacts produced by each of these indices with the United States Drought Monitor. Results suggested this drought incubated around June 2011 and ended in May 2013. While different drought indices depicted drought severity variously. SPI outperformed SPEI and has decent correlation with yield loss especially at a 6 months scale and in the middle growth season, while VegDRI and PADI demonstrated the highest correlation especially in late growth season, indicating they are complementary and should be used together. These results are valuable for comparing and understanding the different performances of drought indices in the Midwestern US. Full article
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Open AccessArticle
Nonlinear Synergetic Governor Controllers for Steam Turbine Generators to Enhance Power System Stability
Energies 2017, 10(8), 1092; doi:10.3390/en10081092 (registering DOI) -
Abstract
This paper proposes a decentralized nonlinear synergetic governor controller (NSGC) for turbine generators to enhance power system stability by using synergetic control theory and the feedback linearization technique. The precise feedback linearization model of a turbine-generator with a steam valve control is obtained,
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This paper proposes a decentralized nonlinear synergetic governor controller (NSGC) for turbine generators to enhance power system stability by using synergetic control theory and the feedback linearization technique. The precise feedback linearization model of a turbine-generator with a steam valve control is obtained, at first, by using a feedback linearization technique. Then based on this model, a manifold is defined as a linear combination of the deviation of the rotor angle, speed deviation, and speed derivative. The control law of the proposed NSGC is deduced and the stability condition of the whole closed-loop system is subsequently analyzed. According to the requirement of the primary frequency regulation, an additional proportional integral (PI) controller is designed to dynamically track the steady-state value of the rotor angle. Case studies are undertaken based on a single-machine infinite-bus system and the New England system, respectively. Simulation results show that the proposed NSGC can suppress the power oscillations and improve transient stability more effectively in comparison with the conventional proportional-integral-derivative (PID) governor controller. Moreover, the proposed NSGC is robust to the variations of the system operating conditions. Full article
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Open AccessFeature PaperArticle
Phase and Microstructural Correlation of Spark Plasma Sintered HfB2-ZrB2 Based Ultra-High Temperature Ceramic Composites
Coatings 2017, 7(8), 110; doi:10.3390/coatings7080110 (registering DOI) -
Abstract
The refractory diborides (HfB2 and ZrB2) are considered as promising ultra-high temperature ceramic (UHTCs) where low damage tolerance limits their application for the thermal protection system in re-entry vehicles. In this regard, SiC and CNT have been synergistically added as
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The refractory diborides (HfB2 and ZrB2) are considered as promising ultra-high temperature ceramic (UHTCs) where low damage tolerance limits their application for the thermal protection system in re-entry vehicles. In this regard, SiC and CNT have been synergistically added as the sintering aids and toughening agents in the spark plasma sintered (SPS) HfB2-ZrB2 system. Herein, a novel equimolar composition of HfB2 and ZrB2 has shown to form a solid-solution which then allows compositional tailoring of mechanical properties (such as hardness, elastic modulus, and fracture toughness). The hardness of the processed composite is higher than the individual phase hardness up to 1.5 times, insinuating the synergy of SiC and CNT reinforcement in HfB2-ZrB2 composites. The enhanced fracture toughness of CNT reinforced composite (up to a 196% increment) surpassing that of the parent materials (ZrB2/HfB2-SiC) is attributed to the synergy of solid solution formation and enhanced densification (~99.5%). In addition, the reduction in the analytically quantified interfacial residual tensile stress with SiC and CNT reinforcements contribute to the enhancement in the fracture toughness of HfB2-ZrB2-SiC-CNT composites, mandatory for aerospace applications. Full article
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Open AccessArticle
Investigation on the Development of a Sliding Mode Controller for Constant Power Loads in Microgrids
Energies 2017, 10(8), 1086; doi:10.3390/en10081086 (registering DOI) -
Abstract
To implement renewable energy resources, microgrid systems have been adopted and developed into the technology of choice to assure mass electrification in the next decade. Microgrid systems have a number of advantages over conventional utility grid systems, however, they face severe instability issues
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To implement renewable energy resources, microgrid systems have been adopted and developed into the technology of choice to assure mass electrification in the next decade. Microgrid systems have a number of advantages over conventional utility grid systems, however, they face severe instability issues due to the continually increasing constant power loads. To improve the stability of the entire system, the load side compensation technique is chosen because of its robustness and cost effectiveness. In this particular occasion, a sliding mode controller is developed for a microgrid system in the presence of constant power loads to assure a certain control objective of keeping the output voltage constant at 480 V. After that, a robustness analysis of the sliding mode controller against parametric uncertainties was performed and the sliding mode controller’s robustness against parametric uncertainties, frequency variations, and additive white Gaussian noise (AWGN) are presented. Later, the performance of the proportional integral derivative (PID) and sliding mode controller are compared in the case of nonlinearity, parameter uncertainties, and noise rejection to justify the selection of the sliding mode controller over the PID controller. All the necessary calculations are reckoned mathematically and results are verified in a virtual platform such as MATLAB/Simulink with a positive outcome. Full article
Open AccessArticle
Venomics of Remipede Crustaceans Reveals Novel Peptide Diversity and Illuminates the Venom’s Biological Role
Toxins 2017, 9(8), 234; doi:10.3390/toxins9080234 (registering DOI) -
Abstract
We report the first integrated proteomic and transcriptomic investigation of a crustacean venom. Remipede crustaceans are the venomous sister group of hexapods, and the venom glands of the remipede Xibalbanus tulumensis express a considerably more complex cocktail of proteins and peptides than previously
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We report the first integrated proteomic and transcriptomic investigation of a crustacean venom. Remipede crustaceans are the venomous sister group of hexapods, and the venom glands of the remipede Xibalbanus tulumensis express a considerably more complex cocktail of proteins and peptides than previously thought. We identified 32 venom protein families, including 13 novel peptide families that we name xibalbins, four of which lack similarities to any known structural class. Our proteomic data confirm the presence in the venom of 19 of the 32 families. The most highly expressed venom components are serine peptidases, chitinase and six of the xibalbins. The xibalbins represent Inhibitory Cystine Knot peptides (ICK), a double ICK peptide, peptides with a putative Cystine-stabilized α-helix/β-sheet motif, a peptide similar to hairpin-like β-sheet forming antimicrobial peptides, two peptides related to different hormone families, and four peptides with unique structural motifs. Remipede venom components represent the full range of evolutionary recruitment frequencies, from families that have been recruited into many animal venoms (serine peptidases, ICKs), to those having a very narrow taxonomic range (double ICKs), to those unique for remipedes. We discuss the most highly expressed venom components to shed light on their possible functional significance in the predatory and defensive use of remipede venom, and to provide testable ideas for any future bioactivity studies. Full article
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Open AccessArticle
Veterinary Pharmaceutics: An Opportunity for Interprofessional Education in New Zealand?
Pharmaceutics 2017, 9(3), 25; doi:10.3390/pharmaceutics9030025 (registering DOI) -
Abstract
Globally pharmacists are becoming increasingly involved in veterinary medicine; however, little is known about the level of interest for pharmacists playing a larger role in animal treatment in New Zealand. A key stakeholder in any progression of pharmacists becoming more involved in the
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Globally pharmacists are becoming increasingly involved in veterinary medicine; however, little is known about the level of interest for pharmacists playing a larger role in animal treatment in New Zealand. A key stakeholder in any progression of pharmacists becoming more involved in the practice of veterinary pharmacy is the veterinary profession. The aim of this study was to investigate views of veterinarians and veterinary students on the role of pharmacists supporting veterinarians with advice on animal medicines. Open interviews were conducted with veterinarians in Dunedin, New Zealand. Veterinary students at Massey University completed an online survey. Most veterinarians do not have regular communication with pharmacists regarding animal care, but believe it may be beneficial. In order to support veterinarians, pharmacists would need further education in veterinary medicine. Veterinary students believe there is opportunity for collaboration between professions provided that pharmacists have a better working knowledge of animal treatment. Most of the veterinary students surveyed perceive a gap in their knowledge concerning animal medicines, specifically pharmacology and compounding. While there is support for pharmacists contributing to veterinary medicine, particularly in the area of pharmaceutics, this is currently limited in New Zealand due to a lack of specialized education opportunities. Full article
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Open AccessFeature PaperArticle
Adaptation: An Agricultural Challenge
Climate 2017, 5(3), 56; doi:10.3390/cli5030056 (registering DOI) -
Abstract
Agriculture is quite sensitive to climate change and to date it has been impacted in many ways. In turn, adaptation to lessen the impacts has attracted increasing attention. Here we discuss private and public roles in adaptation, as well as procedures for the
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Agriculture is quite sensitive to climate change and to date it has been impacted in many ways. In turn, adaptation to lessen the impacts has attracted increasing attention. Here we discuss private and public roles in adaptation, as well as procedures for the evaluation of adaptation projects. Additionally, we discuss adaptation realities and limits that constrain the practical ability of adaptation actions to cope with climate effects. Full article
Open AccessArticle
Sense-making Strategies for the Interpretation of Visualizations—Bridging the Gap between Theory and Empirical Research
Multimodal Technologies Interact. 2017, 1(3), 16; doi:10.3390/mti1030016 (registering DOI) -
Abstract
Making sense of visualizations is often an open and explorative process. This process is still not very well understood. On the one hand, it is an open question which theoretical models are appropriate for the explanation of these activities. Heuristics and theories of
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Making sense of visualizations is often an open and explorative process. This process is still not very well understood. On the one hand, it is an open question which theoretical models are appropriate for the explanation of these activities. Heuristics and theories of everyday thinking probably describe this process better than more formal models. On the other hand, there are only few detailed investigations of interaction processes with information visualizations. We will try to relate approaches describing the usage of heuristics and everyday thinking with existing empirical studies describing sense-making of visualizations. Full article
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