Wyniki wyszukiwania - BazTech

1

Water-exit process modeling and added-mass calculation of the submarine-launched missile

Yang J., Feng J., Li Y., Liu A., Hu J., Ma Z.

Polish Maritime Research

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2017

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S 3

152--164

EN

In the process that the submarine-launched missile exits the water, there is the complex fluid solid coupling phenomenon. Therefore, it is difficult to establish the accurate water-exit dynamic model. In the paper, according to the characteristics of the water-exit motion, based on the traditional method of added mass, considering the added mass changing rate, the water-exit dynamic model is established. And with help of the CFX fluid simulation software, a new calculation method of the added mass that is suit for submarine-launched missile is proposed, which can effectively solve the problem of fluid solid coupling in modeling process. Then by the new calculation method, the change law of the added mass in water-exit process of the missile is obtained. In simulated analysis, for the water-exit process of the missile, by comparing the results of the numerical simulation and the calculation of theoretical model, the effectiveness of the new added mass calculation method and the accuracy of the water-exit dynamic model that considers the added mass changing rate are verified.

2

One step purification of impurities in the leachate of weathered crust elution-deposited rare earth ores

Zhou F., Feng J., Wang Z., Xu Y., Zhang Z., Chi R.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

1188--1199

EN

It is necessary to control and reduce the high content of Al3+, Cu2+ and Pb2+ ions in the leachate of weathered crust elution-deposited rare earth ore to facilitate the rare earth recovery and the quality of rare earth products. Neither NH4HCO3 nor Na2S are suitable for removal of all impurity ions and meanwhile maintain high rare earth recovery. Conventionally, NH4HCO3 is firstly adopted to remove Al3+, and then Cu2+ and Pb2+ are removed by using Na2S. This two steps purification process is quite long and results in lots of complication in operation. In this paper, a one-step purification by using the compound of NH4HCO3 and Na2S was proposed to remove Al3+, Cu2+ and Pb2+. The results showed that after purification 89% Cu, 92% Pb and 74% Al were removed from the leachate solution by using 0.1 M compound of NH4HCO3/Na2S, while maintaining 89% rare earth. The optimal purification parameters were: volume ratio of NH4HCO3 to Na2S of 9:1, volume ratio of compound to leachate of 0.05:1, precipitation time of 30 min.

3

Eddy current density asymmetric distribution of damper bars in bulb tubular turbine generator

Qiu H., Fan X., Yi R., Feng J., Wu J., YANG C., ZHAO H.

Archives of Electrical Engineering

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2017

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Vol. 66, nr 3

571--581

EN

The major reasons that cause the damage of damper bars in the leeward side are found in this paper. It provides a route for the structure optimization design of a hydro generator. Firstly, capacity of a 24 MW bulb tubular turbine generator is taken as an example in this paper. The transient electromagnetic field model is established, and the correctness of the model is verified by the comparison of experimental results and simulation data. Secondly, when the generator is operated at rated condition, the eddy current density distributions of damper bars are studied. And the asymmetric phenomenon of the eddy current density on damper bars is discovered. The change laws of the eddy currents in damper bars are determined through further analysis. Thirdly, through the study of eddy current distributions under different conditions, it is confirmed that the stator slots and armature reaction are the main factors to affect the asymmetric distribution of the eddy current in damper bars. Finally, the studies of the magnetic density distribution and theoretical analysis revealed the asymmetric distribution mechanism of eddy current density.

4

Numerical Study of the Effect of Furrows on Biosonar Beamforming in Aselliscus Stoliczkanus Bat

He W., Feng J., Gao L., Zhang Z., Lu H.

Archives of Acoustics

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2017

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Vol. 42, No. 3

395--399

EN

The Aselliscus Stoliczkanus bat, studied here, has intricately shaped structures surrounding the nostrils. These structures are hypothesised to have influence on animals’ acoustic radiation patterns. Using micro-tomography scanning technique, a 3D digital model of the noseleaf is reconstructed and biosonar beam pattern is analysed using a finite element method based on the 3D noseleaf model. The present research focuses on the conspicuous furrows in noseleaf, and our analysis allows to conclude the followings: a) structural details in noseleaf of Aselliscus Stoliczkanus bat can produce acoustic effects even if it is not adjacent to the nostrils, b) the furrows possess frequency-selective characteristics, c) the furrows have the function to manipulate the direction and width of the outgoing ultrasound wave.

5

Lifetime Distribution and Associated Inference of Systems with Multiple Degradation Measurements Based on Gamma Processes

Pan Z., Feng J., Sun Q.

Eksploatacja i Niezawodność

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2016

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Vol. 18, no. 2

307--313

EN

With development of science and technology, many engineering systems take on high reliable characteristic and usually have complex structure and failure mechanisms, with their reliability being evaluated by multiple degradation measurements. In certain physical situations, the degradation of these performance characteristics would be always positive and strictly increasing. Therefore, the gamma process is usually considered as a degradation process due to its independent and non-negative increments properties. In this paper, we suppose that a system has multiple dependent performance characteristics and that their degradation can be modeled by gamma processes. For such a multivariate degradation involving three or more performance characteristics, we propose to use a multivariate Birnbaum-Saunders distribution and its marginal distributions to approximate the reliability function and give the corresponding lifetime distribution. And then, the inferential method for the model parameters is developed. Finally, for an illustration of the proposed model and method, a simulated example is discussed and some computational results are presented.

PL

Wraz z rozwojem nauki i techniki, powstaje coraz więcej systemów inżynieryjnych o wysokich parametrach niezawodnościowych, które zwykle charakteryzują się złożoną strukturą i złożonymi mechanizmami uszkodzeń. Ocena niezawodności w przypadku takich systemów wymaga pomiarów współwystępujących procesów degradacji . W pewnych sytuacjach fizycznych, degradacja właściwości użytkowych systemu będzie zawsze dodatnia oraz ściśle rosnąca. Proces degradacji jest zwykle procesem gamma, który charakteryzują niezależne i nieujemne przyrosty. W niniejszej pracy, założono, że system ma wiele zależnych charakterystyk pracy oraz że ich degradację można modelować procesem gamma. W przypadkach takiej wielowymiarowej degradacji obejmującej trzy lub więcej charakterystyk pracy zaproponowano zastosowanie rozkładu Birnbauma-Saundersa (uwzględniającego wiele zmiennych) oraz jego rozkładów brzegowych do aproksymacji funkcji niezawodności oraz określania odpowiadającego jej rozkładu czasu pracy. Opracowano metodę wnioskowania dla parametrów modelu. Wreszcie, dla zilustrowania proponowanego modelu oraz metody, omówiono przykład symulacyjny oraz przedstawiono niektóre wyniki obliczeniowe.

6

Stability control of propeller Autonomous Underwater Vehicle based on combined sections method

Qi D., Feng J., Liu A., Hu J., Xu H., Li Y., Ashraf M. A.

Polish Maritime Research

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2015

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S 1

157--162

EN

Learning from the motion principle of quadrotor, a symmetric propeller AUV, which has small size and low velocity is designed. Compared with the AUV equipped with rudders, it has better maneuverability and manipulation at low velocity. According to the Newton-Euler method, the 6 DOF kinematic model and dynamic model of the propeller AUV are established. A stability controller that consists of 3 different PID controllers is designed. It makes the depth and attitude angle as trigger conditions, and the relevant controller is chosen in different moving process. The simulation experiments simulate ideal motion state and disturbed motion state, and experiments results show that the stability controller based on combined sections method can make the best of mature technology of PID, and meet the control requirements in different stages. It has a higher respond speed and accuracy, improving the stability of the propeller AUV under the disturbance of complex ocean currents.

7

Phytoremediation of phenol using Polygonum orientale and its antioxidative response

Wang K., Cai J., Xie S., Feng J., Wang T.

Archives of Environmental Protection

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2015

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Vol. 41, no. 3

39--46

EN

Polygonum orientale with beautiful red flowers can be found as one dominant species in the vicinity of most water bodies and wetlands in China. However, its phytoremediation potential has not been sufficiently explored because little is known about its resistance to inorganic or organic pollutants. We investigated P. orientale response to low and moderate levels of phenol stress (≤ 80 mg L-1). Endpoints included phenol tolerance of P. orientale and the removal of the pollutant, antioxidant enzyme activities, damage to the cell membrane, osmotic regulators and photosynthetic pigments. In plant leaves, phenol stress significantly increased the activities of peroxidase (POD) and catalase (CAT), as well as the contents of proline, soluble sugars and carotenoids, whereas superoxide dismutase (SOD), H2O2 and electrolyte leakage (EL) levels remained unaltered. On the other hand, there were significant decreases of soluble protein and chlorophyll contents. We demonstrated that, in combination with phenol tolerance and its removal, P. orientale has efficient protection mechanisms against phenol-induced oxidative damage (≤ 80 mg L-1). We propose that P. orientale could be used as an alternative and interesting material in the phytoremediation of phenol.

8

DC-Link Voltage Balancing Method with Reduced CommonMode Voltage for a Five-Level ANPC Inverter

Wang K., Li Y., Zheng Z., Xu L., Feng J.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 3b

32--34

EN

This paper presents a DC-link voltage balancing method with reduced common-mode voltage for a five-level active neutral-point clamped (ANPC) inverter. The DC-link voltage balancing method is based on zero-sequence voltage injection using carrier-based PWM. By further limiting the range of injected zero-sequence voltages, the amplitude of common-mode voltage can be reduced to 1/4 of the dc-link voltage. Experimental results are presented to verify the validity of this method.

PL

W artykule przedstawiono metodę balansowania napięciami kondensatorów obwodu pośredniczącego DC dla pięcio-poziomowego falownika Active NPC z redukcją napięcia common-mode. W metodzie wykorzystywana jest modulacja PWM z falą nośną i sygnałem kolejności zerowej, o regulowanym zakresie aplikacji. Przedstawiono wyniki eksperymentalne.

9

Wear properties of hemp, ramie and linen fabrics after liquid ammonia/crosslinking treatment

Li J., Feng J., Zhang H., Zhang J.

Fibres & Textiles in Eastern Europe

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2010

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Vol. 18, no. 5 (82)

81--85

EN

Desized and scoured hemp, ramie and linen fabrics were treated with liquid ammonia over practical ranges, followed by crosslink finishing with modified DMDHEU (Clariant Chemical Co). Appearance qualities, as well as comfort and mechanical properties were measured to investigate the wear behavior of all-cellulosic fabrics. The crease recovery, washing shrinkage and other appearance qualities of cellulosic fabrics were improved by NH3 treatment and especially by liquid ammonia pretreatment in conjunction with crosslink finishing. The moisture regain of the cellulosic fibers was increased by NH3 treatment, but on the other hand, water retention was decreased. The air permeability, moisture permeability and other comfort properties of the cellulosic fabrics were decreased by crosslink finishing, whereas those of NH3/crosslinked fabrics were greater than untreated ones. As a pretreatment for crosslink finishing, liquid ammonia significantly improved the tensile strength retention and tear strength in cellulosic fabrics compared to crosslink finishing alone.

PL

Tkaniny z konopi, ramii oraz lnu po usunięciu klejonki i odtłuszczeniu obrabiano ciekłym amoniakiem i sieciowano DMDHEU (Clariant Chemical Co). W celu określenia zachowania podczas użytkowania tkanin z włókien celulozowych oceniano ich wygląd oraz właściwości mechaniczne. Obróbka NH3 i wstępne działanie ciekłym azotem w połączeniu z sieciowaniem poprawiły odporność tkaniny na gniecenie, kurczliwość po praniu oraz inne cechy wyglądu tkanin. Absorpcja włókien celulozowych wzrosła po obróbce NH3, ale z innej strony, spadła retencja wody. Po sieciowaniu pogorszyła się przepuszczalność powietrza i wilgoci, a także inne właściwości użytkowe tkanin, podczas gdy te same cechy tkanin obrabianych NH3 i sieciowanych były lepsze niż tkanin nie obrabianych. Poprzedzenie sieciowania obróbką ciekłym amoniakiem znacząco polepsza wytrzymałość w porównaniu do tkanin poddanych samemu sieciowaniu.