Wyniki wyszukiwania - BazTech

1

Study on the optimization and performance of TDMA allocation algorithm in ships’ ad hoc networks

Han X., Li Y., Liu G.

Polish Maritime Research

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2018

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S 2

170--175

EN

This paper analyzes the requirements of the information transmission network of ship integrated condition monitoring system, and proposes a design scheme of ship condition monitoring system based on wireless ad hoc network. The wireless ad hoc network protocol was designed, its networking process was analyzed in detail, and the network transmission performance of the monitoring system was tested. The results proved the feasibility of the system. The above solution can be used for the transmission of ship state information that satisfies the requirements of wireless transmission, and has important theoretical and practical significance. The slot allocation algorithm has been receiving extensive attention as an important part of the TDMA system research. This paper analyzes the summarization and summarization of TDMA time slot assignment algorithms from several aspects such as slot synchronization, existing slot allocation algorithm, and slot assignment model, laying an important foundation for researchers to do further research. In the TDMA system, time is divided into non-overlapping time frames, and the time frames are divided into non-overlapping time slots. Each node in the network performs corresponding operations in each time slot.

2

Permeability of P and K-nutrient through polystyrene membrane from aqueous solutions of urea + KH2PO4

Deng X., Liu K., Han X., Hu X., Zheng S.

Polish Journal of Chemical Technology

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2018

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Vol. 20, nr 4

113--122

EN

With the polymer-coated fertilizer as background, the permeability of P- and K-nutrient through a representative polymer membrane-polystyrene membrane were investigated by measuring their permeability in the solutions of KH2 PO4 -water and urea-KH2 PO4 water at nominal temperature of 298 K using the Ussing chamber method. To analyze and interpret the variation of permeability with solute concentration, the solubility of permeate in polymer membrane were determined experimentally and the permeate diffusion coefficient were assessed by the measurements of density and apparent molar volume of the aqueous fertilizer solutions. An interesting “increase-decrease” trend for the permeability of both phosphorous (P)-nutrient, and potassium (K)-nutrient fertilizer with permeate concentration was observed, in which the increases in permeability at low concentrations of permeate could be attributed to the increase in solubility of KH2 PO4 in polymer while the decreases in permeability at high concentrations was due to the decrease in diffusion coefficient of permeate in polymer membrane. Finally, the release kinetics of these nutrients from a PS-coated urea-KH2 PO4 compound fertilizer granule was predicted using the Shaviv’s model along with the permeability data of P- and K-nutrient generated.

3

Mechanical properties and abrasive wear behaviors of in situ nano-TiCx/Al–Zn–Mg–Cu composites fabricated by combustion synthesis and hot press consolidation

Gao Y. Y., Qiu F., Shu S. L., Wang L., Chang F., Hu W., Han X., Li Q., Jiang Q. C.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 1

179--187

EN

The in situ nano-TiCx/Al–Zn–Mg–Cu composites with different TiCx content (20, 25 and 30 vol.%) were successfully fabricated by combustion synthesis and hot press consolidation in Al–Ti–C/CNTs systems. The compressive properties and abrasive wear resistance of the composites improved with the increase in the TiCx content. The transformation of carbon source from pure C black to the mixture of C black and CNTs to pure CNTs in Al–Ti–C/CNTs systems leaded to a significant improvement in the compressive properties and wear resistance of the composites as well as a significant decrease in the average size of TiCx particles. The average size of the nano-TiCx particles in 30 vol.% TiCx/Al–Zn–Mg–Cu composite synthesized by the carbon source of CNTs reached 81 nm, moreover, the yield strength (σ0.2), the ultimate compression strength (σUCS) and the fracture strain (ɛf) of the composite reached 597 MPa, 882 MPa and 21.7%, respectively.

4

Quantitative determination of glycerol in antarctic krill (Euphausia superba Dana) by high-performance thin-layer chromatography

Han X., Liu D.

Acta Chromatographica

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2018

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Vol. 30, no. 4

274--277

EN

In this reported study, a direct high-performance thin-layer chromatographic (HPTLC) method was developed to qualitatively detect and quantitatively determine glycerol in Antarctic krill for the first time. This procedure was based on the extraction of glycerol by ultrasonic solvent extraction with anhydrous ethanol, silica-gel column chromatographic separation, HPTLC detection and quantification using methylene chloride–methanol (5:1, v/v) as the developing solvent and alkaline potassium permanganate as chromogenic agent. The content of glycerol was 1.3725 ± 0.218 mg/g in freeze-dried Antarctic krill. The structure of glycerol in the Antarctic krill was subsequently determined by gas chromatography–mass spectrometry (GC–MS) which verified the presence of the material in the krill. The HPTLC method exhibited excellent accuracy with a recovery of 90.1–103.3% and good precision with a relative standard deviation (RSD) of 1.59–4.84%. The results clearly exhibited the applicability of the proposed for quantifying glycerol in Antarctic krill.

5

Spatial distribution, environmental risk and source of heavy metals in street dust from an industrial city in semi-arid area of China

Han X., Lu X.

Archives of Environmental Protection

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2017

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Vol. 43, no. 2

10--19

EN

Environmental risks associated with Co, Cr, Cu, Mn, Ni, Pb, V and Zn in street dust collected from Baotou, a medium-sized industrial city in a semi-arid area of northwest China, were assessed by using enrichment factor and the potential ecological index. Their spatial distributions and sources in the dust were analyzed on the basis of geostatistical methods and multivariate statistical analysis, respectively. The results indicate that street dust in Baotou has elevated heavy metal concentrations, especially of Co, Cr, Cu, Pb and Zn. Co in the dust was significantly enriched. Cr and Pb were from moderate to significant enrichment. Cu and Zn were from minimal to moderate enrichment, whereas Mn, Ni and V in the dust were from deficient to minimal enrichment. The ecological risk levels of Co and Pb in the dust were moderate to considerable and low to moderate, respectively, whereas those of other heavy metals studied in the dust presented low ecological risk. Different distribution patterns were found among the analyzed heavy metals. Three main sources of these heavy metals were identified. Cr, Mn, Ni and V originated from nature and industrial activities. Cu, Pb and Zn derived mainly from traffic sources, and Co was mainly from construction sources.

6

Electrochemical Behavior of Ascorbic Acid and Uric Acid in the Presence of Micelles and Their Selective Determination Application

Gao Z., Peng J., Han X.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 3

441-454

EN

The electrochemical behavior of ascorbic acid (AA) and uric acid (UA) in both aqueous cetylpyridinium bromide (CPB) and sodium dodecyl benzene sulfonate (SDBS) micellar solutions have been studied by cyclic voltammetry. The oxidation peak potentials shift more negatively, and the peak currents increase in aqueous CPB micellar solutions for AA and UA. However, the oxidation peak potentials shift more positively, and the peak currents decrease in aqueous SDBS micellar solutions for AA and UA. Therefore, CPB can enhance the electrochemical oxidation reaction for AA and UA, and SDBS hinders the electrochemical oxidation reaction. The electrochemical kinetic parameters for AA and UA in both aqueous CPB and SDBS micellar solutions are determined by chronocoulometry (CC) and chronoamperometry (CA). The charge transfer coefficients _ and the electrode reaction rate constants kf for AA and UA are enhanced in aqueous CPB micellar solutions, but reduced in aqueous SDBS micellar solutions. The pulse differential voltammetric behavior for AAand UAare also investigated in this work. The experimental results show that the oxidation peak potentials forAAandUAare separated by 270mVin the presence ofCPB in aqueous PBS (phosphate buffer solution, pH 6.8) solutions. Thus, AA and UA can be selectively determined in aqueous CPB micellar solutions, especially selectively determination of UA in the presence of excess of AA is possible. According to our work, the practical application of the results can be used to determineUAin human urine and serum samples, the determination results are satisfied.