Wyniki wyszukiwania - BazTech

1

Analysis of an N-policy GI/M/1 queue in a multi-phase service environment with disasters

Jiang T., Ammar S. I., Chang B., Liu L.

International Journal of Applied Mathematics and Computer Science

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2018

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Vol. 28, no. 2

375--386

EN

This paper investigates an N-policy GI/M/1 queue in a multi-phase service environment with disasters, where the system tends to suffer from disastrous failures while it is in operative service environments, making all present customers leave the system simultaneously and the server stop working completely. As soon as the number of customers in the queue reaches a threshold value, the server resumes its service and moves to the appropriate operative service environment immediately with some probability. We derive the stationary queue length distribution, which is then used for the computation of the Laplace– Stieltjes transform of the sojourn time of an arbitrary customer and the server’s working time in a cycle. In addition, some numerical examples are provided to illustrate the impact of several model parameters on the performance measures.

2

Calculating study of the turbine at last stage flow field in the small volume flow condition

Jiang T., Jin J., Wang Z., Cao L., Li B.

Polish Maritime Research

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2017

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S 3

23--27

EN

Based on basic equation and boundary layer theory of pneumodynamics, the thesis conducts numerical modeling and theoretical analysis on the last stage of turbine characteristics at a small volume flow by using FLUENT, gives an emphasized analysis on the position of first occurrence of backflow and its expansion direction and comes up with flow structure of the turbine flow field at last stage in the small volume flow condition. In connection with specific experiments, it puts forward the flow model of backflow occurring in the last stage field and the solution to the model. The flow field at last stage for a 100MW turbine in the small volume flow condition that is calculated by using the model is basically in conformity to the actual result.

3

Reverse flotation of ultrafine magnetic concentrate by using mixed anionic/cationic collectors

Lu D., Hu Y., Li Y., Jiang T., Sun W., Wang Y.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

724--736

EN

Compared to reverse cationic flotation, the advantages of reverse anionic flotation include relatively lower sensitivity to slimes and lower reagent cost. Besides, anionic collectors were found to have excellent capability of selectively separating an ultrafine magnetite ore. Addition of a small amount of cationic collector into the anionic collector as the collector mixture can improve the metallurgical results of removing silicates in reverse flotation. In this paper, NaOL and DDA were used for reverse flotation of the ultrafine magnetic concentrate. The separation performance of the collector mixture was investigated at different ratios of NaOL and DDA. The results showed that a better separation performance was obtained for the collector mixture than for NaOL alone. There was an optimal molar ratio between NaOL and DDA equal to 10:1. In the flotation system with the presence of the collector mixture, the good selectivity was found when starch was used as a depressor for magnetite and CaO was used as an activator for quartz. The influences of starch and CaO dosages on the separation performance of magnetite, quartz and chlorite had been investigated through micro-flotation tests. The infrared spectral analysis showed stretching vibration peaks of chemical adsorption of the collector mixture on the magnetite surface. The peaks were not present when starch was used as the depressor for magnetite. The closed flotation tests on the magnetic concentrate with the particle size of -25 μm were performed in the laboratory. The Fe concentrate assaying 64.52 % was obtained with Fe recovery of 80.66%, for the Fe content of feed equal to 52.98%.

4

Full-automatic computer aided system for stem cell clustering using content-based microscopic image analysis

Li C., Huang X., Jiang T., Xu N.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 3

540--558

EN

Stem cells are very original cells that can differentiate into other cells, tissues and organs, which play a very important role in biomedical treatments. Because of the importance of stem cells, in this paper we propose a full-automatic computer aided clustering system to assist scientists to explore potential co-occurrence relations between the cell differentiation and their morphological information in phenotype. In this proposed system, a multi-stage Content-based Microscopic Image Analysis (CBMIA) framework is applied, including image segmentation, feature extraction, feature selection, feature fusion and clustering techni-ques. First, an Improved Supervised Normalized Cuts (ISNC) segmentation algorithm is newly introduced to partition multiple stem cells into individual regions in an original microscopic image, which is the most important contribution in this paper. Then, based on the seg-mented stem cells, 11 different feature extraction approaches are applied to represent the morphological characteristics of them. Thirdly, by analysing the robustness and stability of the extracted features, Hu and Zernike moments are selected. Fourthly, these two selected features are combined by an early fusion approach to further enhance the properties of the feature representation of stem cells. Finally, k-means clustering algorithm is chosen to classify stem cells into different categories using the fused feature. Furthermore, in order to prove the effectiveness and usefulness of this proposed system, we carry out a series of experiments to evaluate our methods. Especially, our ISNC segmentation obtains 92.4% similarity, 96.0% specificity and 107.8% ration of accuracy, showing the potential of our work.

5

Study on pre-concentration efficiency of wolframite from tungsten ore using gravity and magnetic separations

Lu D., Wang Y., Jiang T., Sun W., Hu Y.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 2

718--728

EN

Pre-concentration is effectively applied in recovering wolframite from tungsten ore, due to its benefits of further upgrading tungsten ore and improving separation efficiency. The most important pre-concentration techniques for tungsten ore include gravity separation and magnetic separation, based on the fact that there are appreciable differences, between the desired wolframite and the gangue minerals, in density and magnetic susceptibility. This study investigated the separation efficiency of gravity pre-concentration (Falcon Concentrator) and high-gradient magnetic pre-concentration (SLon VPHGMS) for the beneficiation of a Canada tungsten ore. It is a low-grade type of ore with high silica and arsenic content, and an average content of WO3 is about 0.45%. The optimum conditions for different operational parameters of two pre-concentration separators were studied on this low-grade material. The results presented in this paper suggested that although both pre-concentration techniques were effective for producing pre-concentrates containing high WO3, magnetic pre-concentration showed significantly better separation efficiency. Over 90% of the feed was rejected as the final tailings, meanwhile, over 85% of arsenic minerals were removed with tailings, while the WO3 loss was less than 15%.

6

Phytoplankton pigments and functional community structure in relation to environmental factors in the Pearl River Estuary

Chai C., Jiang T., Cen J., Ge W., Lu S.

Oceanologia

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2016

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No. 58 (3)

201--211

EN

Two cruises were undertaken in the Pearl River Estuary in November 2011 and March 2012 to analyze the distribution of phytoplankton pigments and to define the relationships of pigment indices and functional community structure with environmental factors. Among 22 pigments, 17 were detected by high-performance liquid chromatography. Chlorophyll a was found in all samples, with a maximum of 7.712 μg L-1 in spring. Fucoxanthin was the most abundant accessory pigment, with mean concentrations of 2.914 μg L-1 and 0.207 μg L-1 in spring and autumn, respectively. Chlorophyll a, chlorophyll c2, fucoxanthin, diadinoxanthin, and diatoxanthin were high in the northern or northwest estuary in spring and in the middle-eastern and northeast estuary in autumn. Chlorophyll b, chlorophyll c3, prasinoxanthin, and peridinin were similarly distributed during the two cruises. Chlorophyll a and fucoxanthin positively correlated with nutrients in spring, whereas 19′-hex-fucoxanthin and 19′-but-fucoxanthin negatively correlated. The biomass proportion of microphytoplankton (BPm) was higher in spring, whereas that of picophytoplankton (BPp) was higher in autumn. BPm in spring was high in areas with salinity <30, but BPp and the biomass proportion of nanophytoplankton (BPn) were high in areas with salinity >30. BPm increased but BPn reduced with the increase in nutrient contents. By comparison, BPp reduced with the increase in nutrient contents in spring, but no relationship was found between BPp and nutrient contents in autumn. The ratios of photosynthetic carotenoids to photoprotective carotenoids in the southern estuary approached unity linear relationship in spring and were under the unity line in autumn.

7

Impact of the Volute Basic Circle Diameter of Sewage Pump on Pressure Pulsation

Li W., Shi W., Jiang X., Jiang T., Chen B.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 3b

232--235

EN

The unsteady flow field in the channel sewage pump with three different basic circle diameters of volutes were numerically simulated based on the Fluent commercial software, using the standard k-ε turbulence model, the SIMPLE algorithm, and the sliding mesh technique. By setting pressure measurement points, the pressure pulsation in different positions can be obtained. The impact of the basic circle diameter of volute on the internal pressure pulsation characteristics of a sewage pump was analyzed based on frequency domain and time domain graphs. The results show that the smaller the basic circle diameter of volute is, the more turbulent the pressure pulsation is. The Coefficient of pressure pulsation amplitude reaches the maximum value with small gaps in the volute and impeller clearance. The closer the monitoring point to the cutwater, the greater the amplitude of pressure pulsation. In a flow channel of volute, the pressure fluctuation presents cyclical changes, and a small gap flow reaches the strongest unsteady characteristics. Pressure pulsation cycle is associated with the number of impeller blades and a period of three peaks is the blade passing frequency. The dominant frequency of pressure pulsation is 73.5Hz, which is the threefold frequency of rotation frequency.

PL

W artykule przedstawiono wyniki i opis symulacji przepływu w pompie kanalizacyjnej z trzema różnymi średnicami sprężyn napędowych. W badaniach wykorzystano oprogramowanie Fluent, jeden ze standardowych modeli turbulencji (k-epsilon), algorytm SIMPLE oraz technikę siatki przesuwnej. W analizie skupiono się na przypadku wystąpienia zakłóceń przepływu w kanale. Dokonano analizy wyników i przedstawiono wnioski.

8

Entropy Based Intrusion-tolerant Key Management Scheme with Updatability for Unattended Wireless Sensor Network

Jiang T., Wang L.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1b

33--36

EN

An Unattended Wireless Sensor Network (UWSN) collects the sensing data by using Mobile Sinks (MSs) which will save the battery power and prolong the network lifetime. Unfortunately, UWSNs are usually deployed in unreachable and hostile environments where MSs, who are given too much privilege, can be easily compromised. This will result in security problems. Thus, their security issues should be carefully addressed to deal with node compromise. In this paper, we present a novel key management scheme employing Blundo symmetric polynomial mechanism and the reverse hash chain to secure UWSNs. From the information entropy perspective, we prove that our scheme is intrusion-tolerant against conspiracy attack of t nodes in every group and show that our scheme is robust against node compromised attacks compared with relative schemes.

PL

W niedozorowanych bezprzewodowych sieciach czujnikowych (UWSN) stosuje się zbieranie danych przy pomocy mobilnych stacji (mobile sink,MS). Dzięki temu uzyskuje się oszczędności w poborze mocy baterii oraz wydłużenie czasu życia sieci. UWSN są często umieszczane w niedostępnym i wrogim środowisku, gdzie MS, którym dano za dużo uprawnień, mogą być łatwo skompromitowane. To stwarza problemy bezpieczeństwa, szczególnie starannie rozpatrywane w przypadku kompromitacji węzłów sieci. W opracowaniu, w celu zabezpieczenia UWSN, przedstawiono nowy schemat zarządzania kluczem, wykorzystujący mechanizm symetrycznego wielomianu Blundo i odwrócony ciąg kodowy. Rozpatrując entropię informacji dowiedziono, że, w porównaniu do innych schematów, nasz schemat jest odporny na włamanie wobec ataków na t węzłów w każdej grupie oraz jest silny wobec ataków węzłów skompromitowanych.

9

Research on Metamodel Consistency Verification Based on First-order Logical Inference

Jiang T.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 1b

132-136

EN

Domain-Specific Metamodeling Language (DSMML) defined by informal method cannot strictly represent its structural semantics, so its properties such as consistency cannot be holistically and systematically verified. In response, the paper proposes an approach for verifying metamodels consistency based on formalization of DSMML named XMML. Firstly, we describe our approach of formalization, and then, the approach of consistency verification of XMML and its metamodels based on first-order logical inference is presented, finally, the formalization automatic mapping engine for metamodels is designed and relevant test is performed to show the feasibility of our formal method.

PL

W artykule zaproponowano metodę weryfikacji metamodelu DSMML (Domain Specific Metamodeling Language). Weryfikacja bazuje na interferencji logicznej pierwszego rzędu.

10

Przyspieszone badania degradacji przy stałym naprężeniu w analizie diod superelektroluminescencyjnych i wrażliwości parametrycznej

Li X., Jiang T., Sun F., Ma J.

Eksploatacja i Niezawodność

|

2010

|

nr 2

21-26

PL

Ruchy Browna są jednym z najpotężniejszych procesów stochastycznych w ciągłym czasie i ciągłej przestrzeni, który ma też mocne podstawy fi zyczne. W analizie przyspieszonych badań degradacji (ADT), rozkład odwrotny gaussowski, będący rozkładem czasu pierwszego przejścia ruchu Browna z dryfem (drift Brownian motion), staje się bardzo popularnym modelem predykcji statystycznej życia i niezawodności produktów. Diody superelektroluminescencyjne (SLD) o długiej żywotności i wysokiej niezawodności mają wiele zalet fi zycznych, które sprawiają, że zastępują one diody laserowe (LD) oraz diody elektroluminescencyjne (świecące) (LED) i mają szerokie zastosowanie w czujnikach światłowodowych. W niniejszym artykule przeprowadzono badania ADT diody SLD przy stałym naprężeniu. Aby ocenić możliwość zastosowania rozkładu odwrotnego gaussowskiego do badań diod SLD, określono najpierw trwałość i niezawodność SLD na podstawie danych o spadku mocy optycznej uzyskanych z badania ADT prowadzonego przy stałym naprężeniu. Następnie przeprowadzono analizy wrażliwości parametrycznej w trzech wymiarach: niezawodności, czasu życia i parametru analitycznego. Wreszcie, kierując się wynikami analizy wrażliwościowej, przedstawiono niektóre zasady planowania i przeprowadzania testów ADT przy stałym naprężeniu.

EN

Brownian motion is one of the most powerful stochastic processes in continuous time and continuous space and has a good physics background. For the analysis of accelerated degradation testing (ADT), the inverse Gaussian (IG) distribution, which is the fi rst passage time distribution of the drift Brownian motion (DBM), becomes a very popular statistical prediction model of product life and reliability. Instead of laser diode (LD) and Light Emitting Diode (LED), long-life and high-reliability super-luminescent diode (SLD) has many physical advantages and has been widely used in optical fi ber sensors. In this paper, the constant stress ADT (CSADT) of SLD was conducted. In order to evaluate the applicability of IG distribution to SLD, we fi rst estimate the life and reliability of SLD based on the optical power degradation data collected in CSADT. Then parameter sensitivity analyses are conducted in the 3-dimensions of reliability, lifetime and the analytic parameter. Finally, according to the sensitive analysis results, some CASDT planning and testing principles are presented.