Wyniki wyszukiwania - BazTech

1

Different Ignition Responses of Powdery and Bulky 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) Based Polymer-bonded Explosives under Ultra-high Voltage Electrostatic Discharge

Lyu Z., Long X., Li Z., Dai X., Deng C., He S., Li M., Yao K., Wen Y.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 2

283--298

EN

The electric spark induced ignition mechanism for explosives needs further study. The ignition of powdery and bulky TATB by electrostatic discharge (ESD) was investigated. Up to 200 kV ultra-high voltage ESD was applied to powdery and bulky explosives of two TATB-based polymer-bonded explosives (named PBX-1 and PBX-2). The results showed that the spark sensitivities of powdery and bulky explosives are extremely different for the same formulation. The 50% ignition voltages of powdery PBX-1 and PBX-2 were 10.8 kV and 8.5 kV, respectively, while the values for the bulky samples (tablets) were not less than 200 kV. Both heat and the electric field can be transmitted into the powdery samples, on the other hand only the electric field can be transmitted into the bulk samples. The electric field has a smaller contribution while the heat has a larger contribution to the ignition during an ESD, i.e., the thermal effect plays a main role in the ignition process. Our experimental results are in good agreement with recent results calculated by density functional theory.

2

Controlled Synthesis and Application of Nano-energetic Materials Based on the Copper Oxide/Al System

He S., Chen J., Yang G., Qiao Z., Li J.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 1

129--144

EN

Nanothermite composites containing metal oxide and metal fuel are attracting attention due to their outstanding combustion characteristics. The morphology of metal oxide is important for the performance of nanothermite composites. In this paper, branch-, plate-, sphere-, and hollow sphere-like CuO nano/microstructures were synthesized via a facile hydrothermal process. The CuO/Al based nanothermites were prepared via ultrasonic mixing of the asobtained CuO products and nano-Al. The combustion behaviour of CuO/Al based nanothermites was analyzed by DSC and laser ignition. This study shows that this nanoscale mixing resulted in a large interfacial contact area and low diffusional resistance between the fuel and the oxidizer, and the reaction reflects large energy and laser ignition sensitivity.

3

Design and test of a new high-current electronic current transformer with a Rogowski coil

Zhang M., Li K., He S., Wang J.

Metrology and Measurement Systems

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2014

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Vol. 21, nr 1

121--132

EN

This paper describes the design and test of a new high-current electronic current transformer based on a Rogowski coil. For better performances, electronic current transformers are used to replace conventional electro-magnetic inductive current transformers based on ferromagnetic cores and windings to measure high-current on the high voltage distribution grids. The design of a new high-current electronic current transformer is described in this paper. The principal schemes of the prototype and partial evaluation results are presented. Through relative tests it is known that the prototype has a wide dynamic range and frequency band, and it can allow high accuracy measurements.

4

An on-site calibration system for electronic instrument transformers based on LabVIEW

Zhang M., Li K., Wang J., He S.

Metrology and Measurement Systems

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2014

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Vol. 21, nr 2

257--270

EN

Electronic voltage transformers (EVT) and electronic current transformers (ECT) are important instruments in a digital substation. For simple, rapid and convenient development, the paper proposed an on-site calibration system for electronic instrument transformers based on LabVIEW. In the system, analog signal sampling precision and dynamic range are guaranteed by the Agilent 3458A digital multimeter, and data synchronization is also achieved based on a self-developed PCI synchronization card. To improve the measurement accuracy, an error correction algorithm based on the Hanning window interpolation FFT has good suppression of frequency fluctuation and inter-harmonics interference. The human-computer interface and analysis algorithm are designed based on LabVIEW, and the adaptive communication technology is designed based on IEC61850 9-1/2. The calibration system can take into account pairs of digital output and analog output of the electronic voltage/current transformer calibration. The results of system tests show that the calibration system can meet the requirements of 0.2 class calibration accuracy, and the actual type test and on-site calibration also show that the system is easy to operate with convenience and satisfactory stability.

5

Separating Storm surge from Tidal Level Based on Wavelet Packet Transform

He S., Zhou W.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 3b

107--109

EN

A method of wavelet packet transformation (WPT) is presented in this paper, which regards the tidal level as a signal with containing different frequency of astronomical tidal components and storm surge components. The tidal level signal can be decomposed serials of frequency bands signals by using WPT to carry out time-frequency analysis for procuring the representative frequency bands of storm surge. Then the storm surge process gained by reconstructing the exclusive decomposed wavelet packet coefficients. Taken the typhoon NO.9608 measured tidal level of Xiamen tide station as an example, the storm surge calculates by using the presented method, which compared the value calculated by transformation linear method with the measured value. The result shows that the suggested method can preferably separate storm surge and provide a new way to separate storm surge from short-term tidal level material.

PL

W artykule przedstawiono algorytm realizacji transformaty Falkowej, analizujący dane o astronomicznych parametrach pływów oraz podniesieniu się poziomu morza w czasie sztormu (nagon). Opracowana metoda pomaga w efektywnym odróżnieniu tych dwóch zjawisk, co ogranicza ryzyko fałszywego alarmu. Na podstawie rzeczywistych danych, dokonano jej porównania z metodami liniowymi, co wykazało sprawniejsze działanie.

6

A Hybrid Invasive Weed Optimization with Feasibility-Based Rule for Constrained Optimization Problem

Chen H., Zhou P., Guo P., Ouyang X., He S., Zheng H.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 4

160-167

EN

During the past decade, hybrid algorithms combining evolutionary computation and constraint-handling techniques is one of the most popular method to solve constrained optimization problems. Usually, penalty functions are often used in constrained optimization. But it is difficult to strike the right balance between objective and penalty functions. As a novel population-based algorithm, invasive weed optimization (IWO) algorithm has gained wide applications in a variety of fields, especially for unconstrained optimization problems. In this paper, a hybrid IWO (HIWO) with a feasibility-based rule is proposed to solve constrained optimization problems. The feasibility-based rule does not need additional parameters, which is different from penalty functions. In addition, the complex method is used to provide direction for weed evolution, which can accelerate the convergence speed. Simulation and comparisons based on several well-studied benchmarks demonstrate the effectiveness, efficiency and robustness of the proposed HIWO.

PL

W artykule przedstawiono opracowaną metodę optymalizacji z funkcją kosztu, bazującą na hybrydowej metodzie IWO (ang. Hybrid Invasive Weed Optimizastion) oraz regułach związanych z wykonalnością. Zasady wykonalności, w przeciwieństwie do funkcji kar, nie wymagają dodatkowych parametrów. Dodatkowo zastosowano kompleksową metodę określania kierunki ewolucji trawy w algorytmie IWO, co pozwala na przyspieszenie konwergencji. Przeprowadzone badania symulacyjne i porównawcze dowodzą skuteczności i sprawności proponowanej metody HIWO.

7

Synthesis of claw-like CuO and its catalytic activity in the thermal decomposition of ammonium perchlorate

Wang J., He S., Li Z., Jing X., Zhang M.

Materials Science Poland

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2009

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Vol. 27, No. 2

501--507

EN

Claw-like CuO was prepared by solution process at 100 °C simply by using copper nitrate and hexamethylenetetramine for 3 h. The structure and morphology of resulting CuO powders were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. CuO nanocrystals were studied as an additive for promoting the thermal decomposition of ammonium perchlorate. With the addition of the claw-like CuO nanocrystals, thermal decomposition temperature of ammonium perchlorate decreased. CuO nanocrystals showed catalytic activity on the decomposition of ammonium perchlorate.

8

Controllable synthesis of ZnO nanostructures by a simple solution route

Wang J., He S., Zhang S., Li Z., Yang P., Jing X., Zhang M., Jiang Z.

Materials Science Poland

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2009

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Vol. 27, No. 2

477--484

EN

Flower-shaped ZnO nanostructures, composed of ZnO nanorods, and sphere-shaped ZnO nanoclusters, composed of ZnO nanosheets, were synthesized by reacting zinc acetate dehydrate with sodium hydroxide and polyethylene glycol-20000 (PEG-20000) at 180 °C for 4 h in solution. The thickness of individual nanosheets is about 40-60 nm. The nanorods are of hexagonal shape with sharp tips, and have basic diameters of ca. 450-550 nm. The ZnO nanostructures were characterized by scanning electron microscropy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared, and Raman scattering measurements. The results demonstrated that the synthesized products are single crystalline with wurtzite hexagonal phase, the sphere-shaped ZnO grew in the [100] direction and the flower-shaped ZnO grew in the [001] direction.

9

The study of residual stresses in cold drawn steel wire by means of X-ray diffraction and finite element simulation

Van Houtte P., He S., Mei F., Sarban A.

Hutnik, Wiadomości Hutnicze

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2005

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Vol. 72, nr 2

133-136

EN

Residual stresses caused by cold drawing of low carbon steel wires have been studied. A wire was drawn from 20 mm diameter until 18 mm in one pass. An elastoplastic FEM simulation was performed using several constitutive models for the material. One of them takes the anisotropy due to the crystallographic texture into account. The predicted residual stresses were then compared with those obtained by X-ray diffraction measurements. A good agreement was found.

PL

W pracy przedstawiono analizę naprężeń własnych otrzymanych w procesie ciągnienia drutów wykonanych ze stali niskowęglowej. Drut ciągnięto ze średnicy 20 mm na średnicę 18 mm w jednym ciągu. Przedstawiono wyniki symulacji komputerowej opartej na metodzie elementów skończonych dla elastoplastycznego modelu odkształcenia ciała, użyto kilku modeli konstytutywnych materiału. Jeden z nich uwzględniał anizotropię związaną z teksturą krystalograficzną. Przewidywane naprężenia własne porównano z otrzymanymi z pomiarów dyfrakcji promieniowania rentgenowskiego i otrzymano dużą zgodność wyników.