Wyniki wyszukiwania - BazTech

1

Unravelling the Effect of Anthraquinone Metal Salts as Wide-range Plateau Catalysts to Enhance the Combustion Properties of Solid Propellants

Wang Y., Yan Q.-L., An T., Chen B., Ji Y.-P., Wang W., Zhao F.

Central European Journal of Energetic Materials

|

2018

|

Vol. 15, no. 2

376--390

EN

Novel lead and copper salts based on anthraquinone, including 1,8-dihydroxyanthraquinone,1,4,5,8-tetrahydroxyanthraquinone and 1,8-dihydroxy-4,5-dinitroanthraquinone, were prepared and characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), and X-ray fluorescence (XRF). The catalytic effects of these compounds on the decomposition of nitrocellulose (NC) and on the combustion properties of double-base (DB) and composite modified double-base (CMDB) propellants were comprehensively investigated. The results demonstrated that the burning rate is significantly increased (by 200%) in the lower pressure range (2-6 MPa) as compared to the control systems without added anthraquinone-based salts. Concurrently, the pressure exponents (n) were obviously lower, exhibiting a “wide-range plateau” combustion phenomenon in the middle-pressure region. Specifically, for the DB propellants such a plateau region extended from 10 MPa to 16 MPa for n equal to 0.10, from 10 MPa to 18 MPa for n equal to 0.11 and from 8 MPa to 18 MPa when n is 0.05. In the case of RDX-CMDB propellants, the plateau was found to be in the range 6-18 MPa, with n in the range 0.16-0.27, depending on the type of catalyst, in contrast to the reference CMDB sample, which was characterized by n equal to 0.7 for the same pressure range.

2

An Analytic Investigation of "Hot-Spot" Formation in Compressible Energetic Materials

Li X., Zhao F., Liu J.

Central European Journal of Energetic Materials

|

2017

|

Vol. 14, no. 4

806--820

EN

In this paper, the formation of the shock-induced “hot-spot” in compressible energetic materials has been analyzed. By applying the compressible elastic-viscoplastic material model to a hollow sphere, and solving the governing equations with the initial and boundary conditions, this paper proposes an analytic pore collapse model that is able to simulate the viscoplastic deformation which determines the formation of a “hot-spot”. In this new model there are three mechanisms, of which instantaneous deformation and the subsequent quasi-static incompressible deformation dominate “hot-spot” formation, while quasi-static compressible deformation is of little effect. In comparison with the incompressible solution, this model demonstrates that the bulk compressibility has a great influence on “hot-spot” formation, as the degree of the “hot-spot” reaction is a positive quasi-linear function of Poisson’s ratio ν. An error in Kim’s original pore collapse model has also been discussed.

3

Molecular Dynamics Simulation Studies of the CL-20/DNB Co-crystal

Sun T., Xiao J. J., Ji G. F., Zhao F., Xiao H. M.

Central European Journal of Energetic Materials

|

2016

|

Vol. 13, no. 3

677--693

EN

Molecular dynamics (MD) simulation was conducted for a DNB (1,3-dinitrobenzene) crystal, a ε-CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) crystal, a CL-20/DNB co-crystal and a CL-20/DNB composite. From the calculated maximum bond length (Lmax) of the N−NO2 trigger bond, the cohesive energy density (CED) and the binding energy (Ebind), it was found that the CL-20/DNB co-crystal is more insensitive than its composite. Its thermal stability is also better than that of its composite. The pair correlation function (PCF) analysis method was applied to investigate the interfaces between different molecular layers in the CL-20/DNB co-crystal, and in the composite. Additionally, the calculated mechanical data showed that the moduli of the CL-20/DNB co-crystal and its composite are smaller and their elastic elongation and ductility are better than those of the ε-CL-20 and DNB crystals.

4

Ferrite Decarburization of High Silicon Spring Steel in Three Temperature Ranges

Zhao F., Zhang C. L., Liu Y. Z.

Archives of Metallurgy and Materials

|

2016

|

Vol. 61, iss. 3

1715--1722

EN

Surface decarburization of high silicon spring steel in ambient air was studied. The experimental results confirmed the decarburized mechanism under AC1 temperature, in the temperature range of AC1-AC3 and AC3-G. Under AC1 temperature, pearlite spheroidization and surface decarburization are carried out simultaneously and pearlite spheroidization is reinforced. Considering the oxidation loss depth, the “true ferrite decarburized depth” at 850 °C (AC3-G) is still smaller than that at 760°C (AC1-AC3). That is because an “incubation period” must pass away before ferrite decarburization occurs in the temperature range of AC3-G, and the ferrite decarburized rate is limited to being equal to the partial decarburized rate.

5

Inspection optimization model with imperfect maintenance based on a three-stage failure process

Yang R., Zhao F., Kang J., Li H., Teng H.

Eksploatacja i Niezawodność

|

2015

|

Vol. 17, no. 2

165--173

EN

Rolling element bearings are one of the most widely used and vulnerable components in complex systems. The condition monitoring work is very critical for sustaining the system’s availability and reducing the maintenance cost. Shock pulse method (SPM) is a common technique to measure the operating condition of rolling bearings as a three color scheme, e.g., green, yellow and red. This paper proposes an inspection model based on a three-stage failure process which aims to optimize the inspection interval of bearings by minimizing the expected cost per unit time. The three-stage failure process divides the bearings life into three stages before failure: good, minor defective and severe defective stages, corresponding to the three color scheme of SPM. Considering the need to lubricate bearings when the minor defective stage is identified by inspection in industrial applications, we assume that maintenance at the time of inspection identifying the minor defective stage is imperfect. The concept of proportional age reduction is used to model the effect of imperfect maintenance on the instantaneous rates of the minor defective stage, the severe defective stage and failure. Perfect maintenance however is carried out if inspection detects bearings being in the severe defective stage. Failure can be found once it occurs and replacement has to be implemented immediately. Finally, a numerical example is presented to illustrate the effectiveness of the proposed model.

PL

Łożyska toczne są jednymi z najczęściej stosowanych i jednocześnie najbardziej narażonych na uszkodzenia części składowych układów złożonych. Monitorowanie stanu odgrywa bardzo istotną rolę w utrzymaniu dostępności układów i zmniejszeniu kosztów ich obsługi. Metoda impulsów uderzeniowych (SPM) jest powszechnie stosowaną techniką służącą do pomiaru stanu pracy łożysk tocznych, który reprezentowany jest za pomocą kodu trzech kolorów, na przykład, zielonego, żółtego i czerwonego. W artykule zaproponowano model przeglądów oparty na trójfazowym procesie uszkodzenia, który ma na celu optymalizację częstotliwości przeglądów łożysk poprzez minimalizację oczekiwanych kosztów przypadających na jednostkę czasu. Pojęcie trójfazowego procesu uszkodzenia pozwala podzielić żywotność łożyska na trzy fazy przed wystąpieniem uszkodzenia: fazę dobrego stanu, fazę drobnych defektów i fazę poważnych defektów. Podział ten odpowiada kodowi trzech kolorów SPM. Biorąc pod uwagę konieczność smarowania łożysk po zdiagnozowaniu, podczas przeglądu w warunkach przemysłowych, wystąpienia fazy drobnych defektów, zakładamy, że konserwacja w czasie takiego przeglądu jest konserwacją niepełną. Koncepcja proporcjonalnego obniżenia wieku służy do modelowania wpływu niepełnej konserwacji na chwilowe wartości intensywności fazy drobnych defektów, fazy poważnych defektów oraz uszkodzeń. Gdy podczas przeglądu stwierdzi się, że łożysko jest w fazie poważnych defektów, przeprowadza się pełną konserwację. Uszkodzenie zostaje wykryte zaraz po jego wystąpieniu, i wtedy należy dokonać natychmiastowej wymiany łożyska. Pod koniec artykułu, przedstawiono przykład numeryczny, który ilustruje wydajność proponowanego modelu.

6

A Reactive Prediction Based Dynamic Scheduling Method and its Performance Analysis

Zhao F., Zuo Y., Wang J.

Przegląd Elektrotechniczny

|

2013

|

R. 89, nr 5

176-181

EN

The key problem of improving the efficiency of scheduling and the utilization of resource in manufacture system is the model of scheduling. However, the performance of the scheduling is disturbed by the uncertain elements in the system. This paper proposes a dynamic scheduling method which is based on reactive prediction to solve the interference. The mathematical statistics prediction theory is introduced in scheduling by using the mathematical statistics prediction model in the prediction scheduling. The time series data are obtained in the process of forecasting. The efficiency of distribution in the scheduling is improved by the forecasted data. There have three kinds of measurements consist of MSE, MAD and MAPE to analyze seven kinds of classics mathematical statistics prediction methods. The result shows that the dynamic scheduling method can eliminate the interference of the uncertain element in the scheduling.

PL

W artykule przedstawiono metodę optymalizacji harmonogramu zadań w procesie produkcyjnym w celu zwiększenia sprawności i wykorzystania dostępnych środków. Proponowane rozwiązanie oparte jest na predykcji biernej (matematyka statystyczna), która pozwala na dynamiczne szeregowanie zadań. Przeprowadzone badania, wykazały, że zastosowane szeregowanie zadań zapobiega ich interferencji.

7

An Effective Hybrid Particle Swarm Optimization with Decline Disturbance Index for Expanded Job-shop Scheduling Problem

Zhao F., Tang J., Zou J., Di J.

Przegląd Elektrotechniczny

|

2012

|

R. 88, nr 1b

34-38

EN

In this paper, an improved particle swarm optimization with decline disturbance index (DDPSO), is proposed for expanded job-shop scheduling problem (EJSSP). To balance the exploration and exploitation abilities of DDPSO, both PSO-based global search and an adaptive local search are designed and applied simultaneously in the proposed DDPSO. An index was added when the velocity of the particle is prone to stagnation in the middle and later evolution periods. The modification improves the ability of particles to explore the global and local optimization solutions, and reduces the probability of being trapped into the local optima. Theoretical analysis, which is based on stochastic processes, proves that the trajectory of particle is a Markov processes and DDPSO algorithm converges to the global optimal solution with mean square merit. After the exploration based on DDPSO, neighborhood search strategy is used in a local search and an adaptive Meta-Lamarckian strategy is employed to dynamically decide which neighborhood should be selected to stress exploitation in each generation. Simulation results and comparisons with typical algorithms show the effectiveness and robustness of the proposed DDPSO.

PL

Opisano ulepszony al;gorytm mrówkowy z indeksem DDPSO do rozwiązywania problemu EJSSP (expanded job-shop scheduling problem). Dodano indeks kiedy szybkość cząstki jest podatna na stagnację w środku i końcowej części procesu ewolucji. Analiza teoretyczna bazująca na ;procesach stochastycznych dowodzi że trajektoria cząstki jest procesem Markova i algorytm DDPSO pokrywa się z rozwiązaniem globalnego optimum metodą średniokwadratową.

8

A memetic algorithm combined particle swarm optimization with simulated annealing and its application on multiprocessor scheduling problem

Zhao F., Tang J.

Przegląd Elektrotechniczny

|

2012

|

R. 88, nr 11a

292-296

EN

A memetic algorithm, which combines globe search with local search strategies, is presented to deal with the multiprocessor scheduling problem(MSP). During the processes, an improved particle swarm optimization is employed to execute the globe search optimization, and the simulated annealing is adopted to improve the quality of the selected candidates based on a certain strategy. Simulations show that the proposed method performs well on the globe exploration. Experimental results based on MSP show that the algorithm achieved an efficient makespan.

PL

Przedmiotem artykułu jest algorytm memetyczny do optymalizacji szeregowania zadań w systemie wieloprocesorowym (ang. Multiprocessor Scheduling Problem), łączący w sobie strategie wyszukiwania globalnego i lokalnego. W celu optymalizacji wyszukiwania globalnego zastosowano ulepszoną metodę optymalizacji PSO (ang. Particle Swarm Optimization) oraz algorytm symulowanego wyżarzania (ang. Simulated Annealing) w celu poprawy jakości wybranych elementów.