Wyniki wyszukiwania - BazTech

1

Research on the Mechanical Properties and Curing Networks of Energetic GAP/TDI Binders

Ma S., Li Y., Li Y., Li G., Luo Y.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 3

708--725

EN

This research focused on correlations between the macroscopic mechanical performance and microstructures of energetic binders. Initially a series of glycidyl azide polymer (GAP)/toluene diisocyanate (TDI) binders, catalyzed by a mixture of dibutyltin dilaurate (DBTDL) and triphenyl bismuth (TPB), was prepared. Uniaxial tensile testing, and low-field nuclear magnetic resonance and infrared spectroscopy were then used to investigate the mechanical properties, curing networks, and hydrogen bonding (H-bonds) of these binders. Additionally, a novel method based on the molecular theory of elasticity and the statistical theory of rubber elasticity was used to analyze the integrity of the networks. The results showed that the curing parameter R strongly influences the mechanical properties and toughness of the binders, and that a tensile stress (σm) of 1.6 MPa and an elongation (εm) of 1041% was observed with an R value of 1.6. The cross-linking density increased sharply with the curing parameter, but only modestly with an R value ≥ 1.8. The proportion of H-bonds formed by the imino groups increased with the R value and reached 72.61% at an R value of 1.6, indicating a positive correlation between the H-bonds and σm. Molecular entanglement was demonstrated to increase with R and to contribute dramatically to the mechanical performance. The integrity of these networks, evaluated by a correction factor (A), varies with R, and a network of the GAP/TDI binder with an R value of 1.6 is desirable.

2

Numerical research of the viscous effect of the bilge keel on the damping moment

Deng R., Duan W., Ma S., Ma Y.

Polish Maritime Research

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2015

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S 1

67--74

EN

Bilge keels are effective passive devices in mitigating the rolling motion, and the usage of them covers almost all the sea going vessels. This paper focuses on the viscous effect of the bilge keel, ignored the effect of the free surface and the effect of the ship hull, for the general viscous characteristic of the bilge keel. In order to investigate the viscous effect of the bilge keel on the total damping moment, a special 2 dimensional numerical model, which includes a submerged cylinder with and without bilge keels, is designed for the simulation of forced rolling. Three important factors such as bilge keels width, rolling periods, as well as maximal rolling angles are taken into account, and the viscous flow field around the cylinder is simulated by some codes based on the viscous method in different conditions, in which the three factors are coupled. Verification and validation based on the ITTC method are performed for the cylinder without bilge keels in the conditions of different rolling periods and maximal rolling angles. The primary calculation of damping moment induced by the cylinder with 0mm, 4mm, and 10mm width bilge keels shows some interesting results, and a systematic analysis is conducted. The analysis of the damping moment components suggests there is phase difference between the damping moment induced by the cylinder and the bilge keels, and when the bilge keels width reaches a special size, the total damping moment is mitigated. The calculation of the damping moments induced by the cylinder with some larger bilge keels are also performed, and the results suggest that, the damping moment induced by the bilge keels is increased rapidly and becomes the dominant part in the total damping moment while the width of the bilge keels are increased, but the damping moment induced by the cylinder is not changed significantly. Some illustration of the vortices formation and shedding is included, which is the mechanism of the damping moment caused by the bilge keels. The present work shows an interesting problem, and it is useful for the bilge keel design.

3

TEO-CFCC Characteristic Parameter Extraction Method for Speaker Recognition in Noisy Environments

Li L., An D., Zhao D., Rong C., Ma S.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 2a

118--121

EN

This paper proposes TEO-CFCC characteristic parameter extraction method. Signal phase matching is applied to eliminate speech noise on the basis of CFCC characteristic parameter, and then Teager energy operator is added to the acquisition of CFCC characteristic parameter. In this way TEO-CFCC characteristic parameter is obtained and the energy of speech becomes one of the characteristic parameters for speaker recognition. Experiment results show that the recognition accuracy can reach to 83.2% in a -5dB SNR of vehicle interior noise environment by using TEO-CFCC characteristic parameter.

PL

W artykule przedstawiono metodę wyznaczania parametrów charakterystycznych filtru TEO-CFCC. Zastosowano tu dopasowywanie fazowe sygnału, dla eliminacji z mowy szumów oraz operator Teagera do wyrugowania parametrów. Badania eksperymentalne pokazuję, że dokładność rozpoznania głosu wynosi 83,2% przy -5dB SNR we wnętrzu pojazdu.

4

Location-Unaware Node Scheduling Schemes Based on Boundary Nodes in Wireless Sensor Networks

Ma S., Qian J.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1b

71--74

EN

Node scheduling scheme of sensor nodes is one of the most important method to solve the energy-constrained wireless sensor networks. Traditional methods of node scheduling that without location information leads to a node in the border of monitored region first death due to no more chance enter into sleep state, and then the death spread to the central region. This phenomenon is called as inequality sleep problems. To address this problem, we propose a method to determine some boundary nodes only using the minimum cost of nodes and the neighbors’ distance without any location information. We develop a location-Unaware nodes-scheduling schemes based on these determined boundary nodes called as LUNSB. Simulation results demonstrate that B-LUNS not only alleviates the inequality sleep problems, but also prolongs network lifetime.

PL

Jedną z najważniejszych metod ograniczenia energii sieci czujnikowej jest odpowiedni schemat szeregowania węzłów sieci. W tradycyjnych metodach szeregowania węzły na granicy monitorowanego obszaru uszkadzane są jako pierwsze, ponieważ mają małe szanse na wejście w stan spoczynku. Aby rozwiązać ten problem zaproponowano określenie kilku węzłów granicznych przyjmując, jako kryteria, tylko minimalny koszt oraz odległość do sąsiednich węzłów, bez uwzględnienia lokalizacji. Opracowano schematy szeregowania węzłów o nieznanej lokalizacji LUNSB w oparciu o granice zdefiniowane powyżej. Wyniki symulacji wykazują, że B-LUNS nie tylko łagodzą problem nierównego stanu spoczynku ale i przedłużają czas życia sieci.

5

Research on a Fine-Grained Overriding Mechanism Based on Delegation

Jiao D., Liu L., Ma S.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 5b

93-96

EN

Discretionary Overriding of Access Control is a flexible solution that gives the subject of the access control policy the ability to override the denied access. However, the definition of emergency situations is difficult to express in the mechanism, which may render it inefficient in such situations. In the present work, a fine-grained overriding mechanism based on delegation in presented. In the proposed mechanism, the permissions of the Overriding Ability Subject are delegated from the Overriding Permission Subject, so that users with high-level roles can determine whether or not there exists an emergency situation and whether or not to allow overriding.

PL

System DOAC umożliwia dostęp zewnętrzny w sytuacjach wyjątkowych. W pracy zaproponowano subtelny system udzielania zgody na dostęp oraz możliwość uznania przez upoważnionego użytkownika, że sytuacja jest wyjątkowa.

6

Numerical study of the interface heat transfer characteristics of micro-cooler with CNT structures

Zhang Y., Wang S., Ma S., Hu Z., Liu J., Sitek J., Janeczek K.

Elektronika : konstrukcje, technologie, zastosowania

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2012

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Vol. 53, nr 1

17-19

EN

Micro-cooling techniques provide a promising solution for the thermal management of electronics system with increasing microprocessor powers. Carbon nanotubes (CNTs) can be utilized in micro-coolers as basic materials to constitute the heat dissipation structures inside. The interfaces involved in the CNT-based micro-cooler include the one between the CNT and the coolant, and the CNT and the adhesive. The heat transfer through these interfaces plays an important role in the thermal performance of the micro-cooler. In this paper, numerical investigations on thermal resistance across interfaces between the CNT and other materials are carried out by molecular dynamics simulation (MDS), and various cases are studied.

PL

Technika mikrochłodzenia stanowi obiecujące rozwiązanie w zarządzaniu ciepłem systemów elektronicznych wraz ze wzrostem mocy mikroprocesorów. Nanorurki węglowe (CNTs) mogą być wykorzystane w mikroradiatorach, jako podstawowy material służący do tworzenia struktur rozpraszających ciepło w ich wnętrzu. Interfejsami w mikroradiatorach opartych na CNTs są obszary między CNT i substancją chłodzącą oraz między CNT i klejem. Transfer ciepla przez te interfejsy ma istotny wpływ na wydajność mikroradiatora. W artykule ukazano wyniki analiz numerycznych transferu ciepła przez interfejsy pomiędzy CNT i innymi materiałami przeprowadzone za pomocą symulacji dynamiki molekularnej (MDS) dla różnych przypadków.

7

Structure, magnetic and electrical transport properties of Mn4-xAgxN compounds

Feng W. J., Li D., Zhang Q., Deng Y. F., Ma S., Zhang Z. D.

Materials Science Poland

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2009

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Vol. 27, No. 1

33--42

EN

Mn4-xAgxN compounds (x = 0.0, 0.3, 0.6, 1.0) were prepared by milling and subsequently annealing the mixture of Mn2N0.86, Mn, and Ag powders. All compounds display good single-phase characteristics. Both Mn4N and Mn3.7Ag0.3N exhibit ferrimagnetism, and a little Ag replacement of Mn can improve the saturation magnetization. The magnetic transition of Mn3.4Ag0.6N and Mn3AgN below 15 K is from triangular antiferromagnetism to non-coplanar ferrimagnetism, while the ones at 256 and 275 K (Mn3.4Ag0.6N and Mn3AgN, respectively) have been ascribed to the gradual transition, as temperature increases, from the triangular antiferromagnetic structure T5g to a ferrimagnetic-like one. Two minima appear on the p(T) curves for Mn3AgN, with the observation of a positive magnetoresistance throughout the whole tempeature-dependent change.

8

Tetrahydroxyflavanol-modified TiO2 nanoparticles for solid phase extraction of trace Al(III) and Cr(III) from food and natural water samples

Zheng H., Ma S.

Chemia Analityczna

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2009

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Vol. 54, No. 6

1309-1320

EN

In this work, a novel method using a microcolumn packed with tetrahydroxyflavanol-modi-fied TiO, nanoparticles lor simultaneous preconcentration of trace AI(III) and Cr(IlI) prior to their ICP-OHS determination has been developed. Separation/preconcentration conditions, including pll, sample flow rate and volume, as well as elution conditions and the effect of interfering ions on the recovery of the analytes were investigated. At pH 4, absorption capacity of tetrahydroxyflavanol-modified nano-TiO, was 6.75 mg g-1 and 9.69 mg g-1for AI(III) and Cr(III). respectively. Detection limits (3o) of Al(III) and Cr(III) were 0.49 and 0.21 ng mL-1, respectively. The method was successfully applied to the determination of trace Al(III) and Cr(lII) ions in food and water samples with satisfactory results.

PL

Opracowano nową metodę zatężania śladowych ilości Al(III) i Cr(III) przed oznaczaniem techniką ICP OILS z użyciem mikrokolumny wypełnionej nanocząstkami TiO2 modyfikowanymi tetrahydraksyflawanolem. Zoptymalizowano warunki prowadzenia procesu: pH, szybkość przepływu roztworu próbki, warunki wymywania analitów, a także przeszkadzający wpływ wybranych jonów na ich odzysk. Stwierdzono, że przy pH 4 pojemność sorpcyjna zastosowanego złoża wynosiła 6,75 i 9,69 mg g-1 odpowiednio dla AI(III) i Cr(III). Granice wykrywalności Al(lll) i Cr(III) wynosiły odpowiednio 0,49 i 0,21 ng g-1. Metodę z powodzeniem zastosowano do oznaczania śladowych ilości Al(IlI) i Cr(III) w wodach i produktach żywnościowych.

9

Synthesis and Magnetic Property of a New Dialkoxo-Bridged Bicobalt(II) Complex with Triethanolamine as Ligand

Fu M., Ma S., Zhang L.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 1

159--162

10

Synthesis and Characterization of Three Novel Ferromagnetic Copper(II) Binuclear Complexes Bridged by Phthalato

Ma S., Zhang L. Z.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 11

1537-1543

EN

Three novel copper(II) binuclear complexes with phthalate dianion as bridging ligand have been obtained, namely [Cu2(phth)(L)4](ClO4)2, where phth denotes the phthalate dianion and L represents 1,10-phenanthroline (abbreviated as phen), 2,2_-bipyridine (bpy) or 4,4_-dimethyl-2,2_-bipyridine (Me2bpy). Meanwhile, the IR, electronic spectra, ESR spectra and the temperature-dependent magnetic susceptibility of the three complexes were analyzed. The results of the magnetic analyses show a weak ferromagnetic coupling between the paramagnetic ions in all complexes studied.

11

Dicopper(II) with Ferromagnetic Coupling, Antiferromagnetic Dimanganese(II) Complexes Containing 3-Nitro-phthalato as Bridging Ligand: Synthesis and Magnetism

Ma S., Zhang L. -Z., Tang M. -Y., Lu L. -L.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 7

1041-1046

12

Synthesis and Magnetism of Nickel(II) Binuclear Complexes with Oxamide-N,N'-diacetic Acid

Han K., Tian Z., Wei K., Ma S., Lu L., Meng X., Yang X., He M., Gao J.

Polish Journal of Chemistry

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1999

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Vol. 73, nr 9

1451-1456

EN

Three novel -oxamidato binuclear complexes have been synthesized. The temperature dependences of the magnetic susceptibilities. These results are commensurate with antiferromagnetic interaction between the adjacent metal ions.