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  • 1
    Publication Date: 2016-02-21
    Description: In recent years, we have seen many applications of secure query in two-tiered wireless sensor networks. Storage nodes are responsible for storing data from nearby sensor nodes and answering queries from Sink. It is critical to protect data security from a compromised storage node. In this paper, the Communication-efficient Secure Range Query (CSRQ)—a privacy and integrity preserving range query protocol—is proposed to prevent attackers from gaining information of both data collected by sensor nodes and queries issued by Sink. To preserve privacy and integrity, in addition to employing the encoding mechanisms, a novel data structure called encrypted constraint chain is proposed, which embeds the information of integrity verification. Sink can use this encrypted constraint chain to verify the query result. The performance evaluation shows that CSRQ has lower communication cost than the current range query protocols.
    Electronic ISSN: 1424-8220
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Published by MDPI Publishing
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  • 2
    Publication Date: 2016-06-23
    Description: Nitrogen is an essential nutrient element in crop photosynthesis and yield improvement. Thus, it is urgent and important to accurately estimate the leaf nitrogen contents (LNC) of crops for precision nitrogen management. Based on the correlation between LNC and reflectance spectra, the hyperspectral LiDAR (HSL) system can determine three-dimensional structural parameters and biochemical changes of crops. Thereby, HSL technology has been widely used to monitor the LNC of crops at leaf and canopy levels. In addition, the laser-induced fluorescence (LIF) of chlorophyll, related to the histological structure and physiological conditions of green plants, can also be utilized to detect nutrient stress in crops. In this study, four regression algorithms, support vector machines (SVMs), partial least squares (PLS) and two artificial neural networks (ANNs), back propagation NNs (BP-NNs) and radial basic function NNs (RBF-NNs), were selected to estimate rice LNC in booting and heading stages based on reflectance and LIF spectra. These four regression algorithms were used for 36 input variables, including the reflectance spectral variables on 32 wavelengths and four peaks of the LIF spectra. A feature weight algorithm was proposed to select different band combinations for the LNC retrieval models. The determination coefficient (R2) and the root mean square error (RMSE) of the retrieval models were utilized to compare their abilities of estimating the rice LNC. The experimental results demonstrate that (I) these four regression methods are useful for estimating rice LNC in the order of RBF-NNs > SVMs > BP-NNs > PLS; (II) The LIF data in two forms, including peaks and indices, display potential in rice LNC retrieval, especially when using the PLS regression (PLSR) model for the relationship of rice LNC with spectral variables. The feature weighting algorithm is an effective and necessary method to determine appropriate band combinations for rice LNC estimation.
    Electronic ISSN: 2072-4292
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by MDPI Publishing
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  • 3
    Publication Date: 2016-10-09
    Description: A hollow fiber temperature sensor filled with graphene-Ag composite nanowire and liquid is presented and numerically characterized. The coupling properties and sensing performances are analyzed by finite element method (FEM) using both wavelength and amplitude interrogations. Due to the asymmetrical surface plasmon resonance sensing (SPR) region, the designed sensor exhibits strong birefringence, supporting two separate resonance peaks in orthogonal polarizations. Results show that x-polarized resonance peak can provide much better signal to noise ratio (SNR), wavelength and amplitude sensitivities than y-polarized, which is more suitable for tempertature detecting. The graphene-Ag composite nanowire filled into the hollow fiber core can not only solve the oxidation problem but also avoid the metal coating. A wide temperature range from 22 ∘ C to 47 ∘ C with steps of 5 ∘ C is calculated and the temperature sensitivities we obtained are 9.44 nm/ ∘ C for x-polarized and 5.33 nm/ ∘ C for y-polarized, much higher than other sensors of the same type.
    Electronic ISSN: 1424-8220
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Published by MDPI Publishing
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  • 4
    Publication Date: 2017-06-24
    Description: Reclaimed water is useful for replenishing dried up rivers in North China, although changes in water quality could be an issue. Therefore, it is essential to understand the spatio-temporal variation and the controlling factors of water quality. Samples of Yongding River water were collected seasonally, and 24 water quality parameters were analyzed in 2015. All waters were alkaline, and nitrate-nitrogen was the main form of nitrogen, while phosphorus was mostly below detection level. The water quality parameters varied in time and space. Cluster analysis showed a distinct difference between winter and the other seasons and between the natural river section and the section with reclaimed water. Based on the analysis of Gibbs plots, principal component analysis, and ionic relationships, the water chemistry was controlled by dissolution of rocks in natural river section, the quality of replenished water, the effects of dilution, and the reaction of aqueous chemistry in the reclaimed water section. The positive oxidation environment in most of the river water was conducive to the formation of nitrate-nitrogen by nitrification, and not conducive to denitrification.
    Electronic ISSN: 2073-4441
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI Publishing
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  • 5
    Publication Date: 2018-05-12
    Description: IJERPH, Vol. 15, Pages 964: Biodegradation of Di-(2-ethylhexyl) Phthalate by Rhodococcus ruber YC-YT1 in Contaminated Water and Soil International Journal of Environmental Research and Public Health doi: 10.3390/ijerph15050964 Authors: Ting Yang Lei Ren Yang Jia Shuanghu Fan Junhuan Wang Jiayi Wang Ruth Nahurira Haisheng Wang Yanchun Yan Di-(2-ethylehxyl) phthalate (DEHP) is one of the most broadly representative phthalic acid esters (PAEs) used as a plasticizer in polyvinyl chloride (PVC) production, and is considered to be an endocrine-disrupting chemical. DEHP and its monoester metabolites are responsible for adverse effects on human health. An efficient DEHP-degrading bacterial strain Rhodococcus ruber YC-YT1, with super salt tolerance (0–12% NaCl), is the first DEHP-degrader isolated from marine plastic debris found in coastal saline seawater. Strain YC-YT1 completely degraded 100 mg/L DEHP within three days (pH 7.0, 30 °C). According to high-performance liquid chromatography–mass spectrometry (HPLC-MS) analysis, DEHP was transformed by strain YC-YT1 into phthalate (PA) via mono (2-ethylehxyl) phthalate (MEHP), then PA was used for cell growth. Furthermore, YC-YT1 metabolized initial concentrations of DEHP ranging from 0.5 to 1000 mg/L. Especially, YC-YT1 degraded up to 60% of the 0.5 mg/L initial DEHP concentration. Moreover, compared with previous reports, strain YC-YT1 had the largest substrate spectrum, degrading up to 13 kinds of PAEs as well as diphenyl, p-nitrophenol, PA, benzoic acid, phenol, protocatechuic acid, salicylic acid, catechol, and 1,2,3,3-tetrachlorobenzene. The excellent environmental adaptability of strain YC-YT1 contributed to its ability to adjust its cell surface hydrophobicity (CSH) so that 79.7–95.9% of DEHP-contaminated agricultural soil, river water, coastal sediment, and coastal seawater were remedied. These results demonstrate that R. ruber YC-YT1 has vast potential to bioremediate various DEHP-contaminated environments, especially in saline environments.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by MDPI Publishing
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  • 6
    Publication Date: 2017-05-11
    Description: Spherical microphone arrays have been paid increasing attention for their ability to locate a sound source with arbitrary incident angle in three-dimensional space. Low-frequency sound sources are usually located by using spherical near-field acoustic holography. The reconstruction surface and holography surface are conformal surfaces in the conventional sound field transformation based on generalized Fourier transform. When the sound source is on the cylindrical surface, it is difficult to locate by using spherical surface conformal transform. The non-conformal sound field transformation by making a transfer matrix based on spherical harmonic wave decomposition is proposed in this paper, which can achieve the transformation of a spherical surface into a cylindrical surface by using spherical array data. The theoretical expressions of the proposed method are deduced, and the performance of the method is simulated. Moreover, the experiment of sound source localization by using a spherical array with randomly and uniformly distributed elements is carried out. Results show that the non-conformal surface sound field transformation from a spherical surface to a cylindrical surface is realized by using the proposed method. The localization deviation is around 0.01 m, and the resolution is around 0.3 m. The application of the spherical array is extended, and the localization ability of the spherical array is improved.
    Electronic ISSN: 1424-8220
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Published by MDPI Publishing
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  • 7
    Publication Date: 2018-08-08
    Description: Acid-sensing ion channels (ASICs) have emerged as important, albeit challenging therapeutic targets for pain, stroke, etc. One approach to developing therapeutic agents could involve the generation of functional antibodies against these channels. To select such antibodies, we used channels assembled in nanodiscs, such that the target ASIC1a has a configuration...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 8
    Publication Date: 2015-12-17
    Description: This paper proposes an optimal design of a middle motor integrated into a mid-drive unit for pedal electric cycles. This middle motor is an axial-flux permanent magnet brushless DC motor with a stator plate. Facing this plate is a rotor plate that acts as an eccentric component of a cycloidal reducer next to the stator. Both the middle motor and cycloidal reducer are easily installed on the same axle of the bike crankset. In the preliminary design, driving requirements are used to make the middle motor specifications. The numbers of stator slots and magnet poles on the rotor were chosen to achieve the best winding factor, and the winding layout was determined accordingly. A one-dimensional magnetic circuit model of the middle motor was built, and its shape was optimized utilizing a multifunctional optimization system tool. Finally, the resulting design was verified and refined by a finite element analysis. A prototype of the middle motor was fabricated with a stator made of a soft magnetic composite and integrated with a cycloidal reducer. Experimental results show that the motor has a sinusoidal back electromotive force. Additionally, it is easily controlled by sinusoidal currents with acceptable torque and speed curves.
    Electronic ISSN: 1996-1073
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI Publishing
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  • 9
    Publication Date: 2015-10-27
    Description: To minimize cargo theft during transport, mobile radio frequency identification (RFID) grouping proof methods are generally employed to ensure the integrity of entire cargo loads. However, conventional grouping proofs cannot simultaneously generate grouping proofs for a specific group of RFID tags. The most serious problem of these methods is that nonexistent tags are included in the grouping proofs because of the considerable amount of time it takes to scan a high number of tags. Thus, applying grouping proof methods in the current logistics industry is difficult. To solve this problem, this paper proposes a method for generating multilayered offline grouping proofs. The proposed method provides tag anonymity; moreover, resolving disputes between recipients and transporters over the integrity of cargo deliveries can be expedited by generating grouping proofs and automatically authenticating the consistency between the receipt proof and pick proof. The proposed method can also protect against replay attacks, multi-session attacks, and concurrency attacks. Finally, experimental results verify that, compared with other methods for generating grouping proofs, the proposed method can efficiently generate offline grouping proofs involving several parties in a supply chain using mobile RFID.
    Electronic ISSN: 1424-8220
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Published by MDPI Publishing
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  • 10
    Publication Date: 2017-02-27
    Description: According to the published literature, we surmise that particulate matter (PM) concentration, individually, may be less important than components in explaining health effects. PM2.5 (aerodynamic diameter 〈2.5 μm) had similar cytotoxicity (e.g., cell viability reduction, oxidative damage, inflammatory effects and genetic toxicity) on different types of cells. The studies of cells are readily available for detailed mechanistic investigations, which is more appropriate for learning and comparing the mechanism caused by single or mixed ingredients coating a carbon core. No review exists that holistically examines the evidence from all components-based in vitro studies. We reviewed published studies that focus on the cytotoxicity of normal PM2.5. Those studies suggested that the toxicity of mixed compositions differs greatly from the single ingredients in mixed components and the target cells. The cytotoxic responses caused by PM2.5 components have not shown a consistent association with clear, specific health effects. The results may be beneficial for providing new targets for drugs for the treatment of PM2.5-related diseases.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by MDPI Publishing
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