Wyniki wyszukiwania - BazTech

1

The impact of changes in pore structure on the compressive strength of sulphoaluminate cement concrete at high temperature

Tchekwagep J. J. K., Zhao P., Wang S., Huang S., Cheng X.

Materials Science Poland

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2021

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Vol. 39, No. 1

75--85

EN

The internal pore structure of sulphoaluminate cement concrete (SACC) significantly affects its mechanical properties. The main purpose of this study was to establish the relationship between pore structure changes and compressive strength after exposure to elevated temperatures. SACC samples that had been cured for 12 months were dried to a constant weight and then exposed to different temperatures (100 °C, 200 °C and 300 °C), after which the compressive strength and pore structure were measured. The pore structure of SACC was quantitatively described by mercury intrusion porosimetry (MIP) and nitrogen adsorption results. The results showed that with increased temperature, the porosity of the SACC samples also increased and the pore structure was gradually destroyed. Moreover, the SACC’s compressive strength gradually decreased with increasing temperature. The relationship between compressive strength and porosity was in close agreement with the compressive strength–porosity equation proposed by Schiller. Therefore, after extensive exposure to elevated temperature, the changes in SACC’s compressive strength can be quantitatively described by the Schiller equation.

2

Prediction of the height of overburden fractured zone in deep coal mining: case study

Han Y., Cheng J., Huang Q., Zou D. H. S., Zhou J., Huang S., Long Y.

Archives of Mining Sciences

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2018

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Vol. 63, no. 3

617--631

EN

In the process of coal extraction, a fractured zone is developed in the overburden above the goaf. If the fractured zone is connected with an aquifer, then water inrush may occur. Hence, research and analysis of the height of overburden fractured zone (HOFZ) are of considerable significance. This study focuses on the HOFZ determination in deep coal mining. First, general deformation failure characteristics of overburden were discussed. Second, a new method, numerical simulation by orthogonal design(NSOD), have been proposed to determinate the HOFZ in deep coal mining. Third, the validity of NSOD is verified in the practical application, compared with empiric al formula in Chinese Regulations and in-situ test. These three methods were applied to determine the HOFZ of working face No. 111303 in No. 5 coal mine. The pre dicted HOFZ of NSOD is found to be similar to the result of the in-situ test (8.9% relative error), whereas the HOFZ calculated by the empirical formula has extremely large error (25.7% relative error). Results show that the NSOD can reliably predict the HOFZ in deep coal mining and reduce time and expenses required for in-situ test.

PL

W trakcie prowadzenia wydobycia węgla w warstwie skalnej leżącej ponad zrobami powstaje strefa spękań. Jeśli nieciągłości te związane są z formacjami wodonośnymi, może nastąpić nagły wypływ wód do kopalni. Stąd też waga problemu i konieczność badania wysokości strefy spękań w warstwach nadkładu zalegających nad wyrobiskiem. W pracy tej główny nacisk położono na określenie wysokości strefy spękań warstwy nadkładu zalegającej ponad wyrobiskiem w kopalni podziemnej. W pierwszej części pracy przedstawiono główne charakterystyki powstawania deformacji i pęknięć w warstwach nadkładu. Następnie zaproponowano nową metodę symulacji numerycznych w układzie ortogonalnym i jej wykorzystanie do określania wysokości strefy spękań w warstwach nadkładu w kopalni podziemnej. Następnie powyższą metodę zweryfikowano w praktycznym zastosowaniu, jako poziomy odniesienia wykorzystano odpowiednie wzory empiryczne określone w przepisach obowiązujących w Chinach oraz wyniki pomiarów in-situ. Powyższe trzy metody zastosowane zostały do określenia wysokości strefy spękań w warstwach nadkładu przy prowadzeniu ściany 111303 w kopalni węgla nr 5. Wyniki obliczeń wysokości strefy spękań uzyskane w oparciu o zaproponowaną nową metodę w dużym stopniu pokrywały się z wynikami pomiarów in-situ (błąd względny 8.9%); podczas gdy obliczenia wysokości strefy spękań w oparciu o odpowiednie wzory empiryczne obarczone były dużym błędem (błąd względny 25.7%). Uzyskane wyniki wskazują wiarygodność obliczeń w oparciu o zaproponowaną metodę, co pozwoli na ograniczenie czasu i kosztów związanych z wykonywaniem pomiarów in-situ.

3

Temporal characteristics detection and attribution analysis of hydrological time-series variation in the seagoing river of southern China under environmental change

Chen L., Wang Y., Touati B., Guan H., Leng G, Liu W., Lv S., Huang S., Pan Z.

Acta Geophysica

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2018

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Vol. 66, no. 5

1151--1170

EN

Environmental changes have led to a growing conflict between water supply and demand in Qinjiang River. This paper used the data of monthly rainfall, runoff, evaporation and air temperature during the period from 1956 to 2016 and combined 3-year running mean, linear regression method, Mann–Kendall test and R/S analysis method to analyze the change trend of each factor, combined Mann–Kendall test, cumulative anomaly method and slide t test to analyze the variation of each factor and combined Morlet continuous wavelet analysis to identify periodic oscillations. In this paper, the influences of climate change and human activities on the runoff of the Qinjiang River were qualitatively assessed from the aspects of trend, variation and periodicity and the contributions of climate change and human activities to runoff reduction were quantitatively assessed using evaporation difference method and an improved comparative method of the slope changing ratio of cumulative quantity (SCRCQ).The following results were obtained: (1) From 1956 to 2016, the rainfall showed a weak increasing trend, whereas the runoff depth and the evaporation exhibited significant decreasing trend and the air temperature exhibited a significant increasing trend. The rainfall and air temperature will continuously increase, whereas runoff and evaporation will continuously decrease in the future. (2) Rainfall exhibited no significant variation, whereas there were two variation points (1986 and 2003) in the runoff, three variation points (1974, 1986 and 2011) in evaporation and one variation point (1996) in air temperature. (3) Features of rainfall exhibited similarities to periodic changes in runoff, whereas rainfall exhibited significant difference with evaporation and air temperature. (4) Human activities contributed mainly to the runoff reduction. The contribution of human activities to runoff reduction increased from 43.78 to 61.17% in BR period (1983–2003) and increased from 61.17 to 72.66% in CR period (2004–2016). This indicated that the contribution of human activities to runoff reduction increased continuously. The impact of human activities on the reduction in runoff in the Qinjiang River Basin is mainly due to the irrigation, industrial and urban residents’ water use, which is caused by the growth of population and the growth of economic index.

4

Simultaneous quantitative determination of active components in Tetrastigma hemsleyanum by RP-HPLC coupled with diode array detection

Zhu Y., Yin Q., Du P., Huang S., Yang Y.

Acta Chromatographica

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2018

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Vol. 30, no. 3

186--190

EN

An effective, reliable, and sensitive reversed-phase high-performance liquid chromatography (RP-HPLC) with diode array detector (DAD) method was investigated for simultaneous determination of polydatin, isoquercitrin, resveratrol, and nicotiflorin in Tetrastigma hemsleyanum. The chromatographic separation of the four compounds was carried out on a Welchrom ODS column (4.6 mm × 250 mm, 5 μm) by gradient elution with phosphoric acid (H3PO4) aqueous solution (0.4%)–methanol as the mobile phase, at the temperature of 30 °C and a flow rate of 1.0 mL/min. The detection wavelength was set at 270 nm. Under optimum conditions, the baseline separation of these four compounds can be performed within 30 min. The developed method was validated in terms of detection limit, quantification limit, linearity, precision, and recovery tests. Eventually, the established HPLC–DAD method was successfully applied to the simultaneous determination of polydatin, isoquercitrin, resveratrol, and nicotiflorin in the extract of herb T. hemsleyanum.

5

Numerical test on polystyrene tunnel seismic-isolation material

He J., Chen W., Zhao W., Huang S., Yao Y.

Polish Journal of Chemical Technology

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2016

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Vol. 18, nr 3

122--127

EN

Stress-strain mechanical properties of polystyrene foam plastic material were tested under different loading conditions. An empirical constitutive model for describing metal materials was proposed for the polystyrene plastic foam. The static and dynamic tests results show that the ductility and watertightness of the polystyrene plastic foam are significantly improved. At the same time, in order to check its seismic-isolation property, the high-performance foam concrete as filling materials of Galongla tunnel in Tibet was simulated by FEM. The simulated results show that the polystyrene plastic foam can remarkably decrease the stress and the plastic zone in final lining, so it can effectively reduce the seismic damage of the tunnel. Considering the seismic-isolation property and low price of polystyrene plastic foam, it is a good reference for the anti-seismic design of tunnels in high intensity zones.

6

Dynamic Characteristic Analysis of the Needle Multi-linkage Mechanism in a Carpet Tufting Machine’s Driving System

Xu Y., Sun Z., Huang S., Sheng X., Chi X.

Fibres & Textiles in Eastern Europe

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2016

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Vol. 24, no. 3 (117)

103--109

EN

In a typical carpet tufting machine, kinematic and dynamic characteristics of the needle multi-linkage mechanism are the important factors affecting the quality of the tufting carpet. For providing a rational basis for mechanism design and vibration characteristic analysis, a mathematical model of the needle multi-linkage mechanism is constructed using the complex vector analysis method. On the basis of the model, kinematic characteristic curves and dynamic characteristic curves of the needle multi-linkage mechanism are analyzed by simulation methods. Finally experimental validation of the alternating load dynamic characteristics is performed on the needle multi-linkage mechanism in a typical carpet tufting machine. The results prove the theoretical analysis validity of the needle multi-linkage mechanism.

PL

W typowej maszynie wiążącej dywany charakterystyki kinematyczne i dynamiczne mechanizmu napędzającego układ igieł są bardzo ważnym czynnikiem określającym jakość wytwarzanych dywanów. Dla otrzymania racjonalnej podstawy dla projektowania mechanizmu i analizy charakterystyk wibracyjnych opracowano matematyczny model mechanizmu napędzającego igły. Przy opracowaniu modelu zastosowano metodę kompleksowej analizy wektorowej. Posłużyło to do otrzymania kinematycznych i dynamicznych krzywych przebiegu. Przebiegi te analizowano za pomocą metod symulacji. Następnie oceniono wyniki eksperymentalnie stosując typową maszynę do wytwarzania dywanów. Wyniki potwierdziły prawidłowość przyjętych teoretycznie zależności.

7

Fabrication of polymer microcomponents using CO2 laser melting technique

Tan W. S., Zhou J. Z., Huang S., Zhu W. L., Meng X. K.

Polimery

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2015

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T. 60, nr 3

192--198

EN

A new method of laser melting molding to produce high-efficiency and high-quality polymer microcomponents was proposed. Numerical simulation was used to analyze the temperature changes of polymer melt during the laser irradiation process. An orthogonal experiment was also employed to investigate the factors influencing molding accuracy. The molding experiments were conducted on molds with various degrees of roughness, and the surface quality of the molded pieces was tested. The simulation analysis and experimental results showed that the laser power plays a critical role in improving the repetition accuracy. The next factors are irradiation time and mold temperature, followed by molding force. Optimized technological parameters (1.2 W of laser power, 6 mm of laser beam width, 6 s irradiation time, 150 N molding force, and 80 °C mold temperature) were applied to obtain a molded pieces with high repetition accuracy and a microstructure dimensional deviation of less than 1 µm. Using a mold with lower surface roughness provides that we can obtain a molded piece with lower roughness, the roughness difference between the mold and the molded piece was less than 0.012 µm.

PL

Zaproponowano nową metodę formowania mikroelementów polimerowych z zastosowaniem topienia laserowego, zapewniającą wysoką wydajność oraz dobrą jakość wytwarzanych mikroelementów. Istotnym parametrem procesu, wpływającym na jakość formowanych elementów, jest temperatura stopu polimeru. Do analizy zmian tej temperatury pod wpływem napromieniania laserem zastosowano symulację numeryczną. Zastosowano także ortogonalny plan eksperymentu w celu zbadania czynników wpływających na dokładność formowania. Formowania przeprowadzono z użyciem form o różnych stopniach chropowatości i zbadano jakość powierzchni mikroelementów. Analiza wyników symulacji i badań eksperymentalnych wykazała, że moc lasera odgrywa kluczową rolę w uzyskaniu powtarzalnej dokładności. Kolejnymi czynnikami są czas napromieniowania i temperatura formy oraz siły formujące. Zoptymalizowane parametry technologiczne (moc lasera 1,2 W, szerokość wiązki lasera 6mm, czas napromieniania 6 s, siła formująca 150 N i temperatura formowania 80 °C) zastosowano do formowania elementów z powtarzalną dużą dokładnością odtwarzania wymiarów (odchylenia wymiarów nie przekraczały 1 µm). Użycie form o mniejszej chropowatości powierzchni pozwalało także uzyskać mniejszą chropowatość mikroelementów, przy czym różnica chropowatości formy i otrzymanego elementu była mniejsza niż 0,012 µm.

8

3D loss and heat analysis at the end region of 4-poles 1150 MW nuclear power turbine generator

Zhou G., Han L., Fan Z, Liao Y., Huang S.

Archives of Electrical Engineering

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2014

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Vol. 63, nr 1

47-61

EN

To study the principle of loss and heat at the end region of large 4-poles nuclear power turbine generator, 3D transient electromagnetic field and 3D steady temperature field finite element (FE) models of the end region are established respectively. Considering the factors such as rotor motion, core non-linearity and time-varying of electromagnetic field, the anisotropic heat conductivity and different heat dissipation conditions of stator end region, a 50 Hz, 1150 MW, 4-poles nuclear power turbine generator is investigated. The loss and heat at the generator end region are calculated respectively at no-load and rated-load, and the calculation results are compared with the test data. The result shows that the calculation model is accurate and the generator design is suitable. The method is valuable for the research of loss and heat at the end region of large 4-poles nuclear power turbine generator and the improvement of the generator’s operation stability. The method has been applied successfully for the design of the larger nuclear power turbine generators.

9

A Modelling Approach for Workflow Constrained by Inputs and Outputs

Zheng C., Huang S., Liu X., Yao Y.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 3b

156--160

EN

Workflow systems have been studied for years, but there is not so much research in workflow testing. The key point for workflow testing is to model a workflow. In this paper, a formalized definition of workflow constrained by inputs and outputs is presented first. Based on the definition and the traditional Petri Net, a kind of I/O_WF_NET model is proposed. In that model, the activities of the workflow are modelled as transitions and the inputs and outputs of an activity are modelled as places. The modelling approach for workflow constrained by inputs and outputs is also presented. And a case study is given to show how to apply this approach and the validity of the proposed modelling method.

PL

W artykule przedstawiono model przepływu pracy (workflow), oparty na schemacie Petri Net. Wstępnie zdefiniowano sam model wraz z ograniczeniami wejść i wyjść. Na tej podstawie prowadzono dalsze prace. Opisano sposób modelowania przepływu informacji oraz elementów wejścia i wyjścia. Przeprowadzono także badanie warunkach rzeczywistych w celu weryfikacji proponowanego modelu.

10

Projection of low flow conditions in Germany under climate change by combining three RCMs and a regional hydrological model

Huang S., Krysanova V., Hattermann F.F.

Acta Geophysica

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2013

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Vol. 61, no. 1

151--193

EN

The present study is aimed to: (a) project future low flow conditions in the five largest river basins in Germany, and (b) to account for the projections uncertainties. The eco-hydrological model SWIM was driven by different regional climate models (REMO, CCLM, and Wettreg) to simulate daily river discharg es in each study basin. The 50-year low flow was estimated for the period 1961 to 2000, and its return period was assessed for two scenario periods, 2021-2060 and 2061-2100, using the generalized extreme value distribu tion. The 50-year low flow is likely to occur more frequently in western, southern, and parts of central Ger- many after 2061, as suggested by more than or equal to 80 per cent of the model runs. The current low flow period (from August to September) may be extended until late autumn at the end of this century. The return period of 50-year deficit volume shows a similar temporal and spatial pattern of change as for the low flow, indicating slightly less severe con- ditions with lower confidence. When compared with flood projections for the same area using the same models, the severer low flows projected in this study appear more pronounced, consistent, and have lower uncertainty.

11

Climatological drivers of changes in flood hazard in Germany

Hattermann F.F., Kundzewicz Z.W., Huang S., Vetter T., Gerstengarbe F.-W., Werner P.

Acta Geophysica

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2013

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Vol. 61, no. 2

463--477

EN

Since several destructive floods have occurred in Germany in the last decades, it is of considerable interest and relevance (e.g., when undertaking flood defense design) to take a closer look at the climatic factors driving the changes in flood hazard in Germany. Even if there also exist non-climatic factors controlling the flood hazard, the present paper demonstrates that climate change is one main driver responsible for the increasing number of floods. Increasing trends in temperature have been found to be ubiquitous in Germany, with impact on air humidity and changes in (intense) precipitation. Growing trends in flood pronecirculation pattern and heavy precipitation are significant in many regions of Germany over a multi-decade interval and this can be translated into the rise of flood hazard and flood risk.

12

Mathematic Simulating of Levofloxacin Release from Chitosan Nano/Microparticles

Guan J., Cheng P., Huang S., Li Z., Wu J., Gao P., Wang X., Zhang H.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 7b

345--349

EN

Chitosan based levofloxacin nano/microparticles were prepared by ionotropic gelatin and emulsion crosslinking technique. Their in vitro release profiles showed that microparticles had better sustaining delivery property than nanoparticles. The best fitting kinetics for nanoparticles and microparticles were First Order and Diffusion-Relaxation model respectively. The result suggests that levofloxacin delivery from nanoparticles was mainly controlled by diffusion process only, and that from microparticles was dominated by both diffusion and relaxation process.

PL

Mikro- i nanoelementy lekarstwa levofloaxin były wytwarzane techniką sieciowania emulsji. Dla lepszego dopasowania kinematyki opracowano model matematyczny. Stwierdzono że nanocząstki dostarczają materiał przez dyfuzję podczas gdy mikrocząstki wykorzystują też relaksację.

13

On (…)-centralizers of semiprime rings

Huang S., Haetinger C.

Demonstratio Mathematica

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2012

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Vol. 45, nr 1

29-34

EN

Let R be a semiprime ring with center Z(R) and (…) be a surjective ho-omorphism. In this paper, we prove that T is a (…)-centralizer if one of the following holds: (…).

14

Seasonal temperature extremes in Potsdam

Kundzewicz Z.W., Huang S.

Acta Geophysica

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2010

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Vol. 58, no. 6

1115-1133

EN

The awareness of global warming is well established and results from the observations made on thousands of stations. This paper complements the large-scale results by examining a long time-series of highquality temperature data from the Secular Meteorological Station in Potsdam, where observation records over the last 117 years, i.e., from January 1893 are available. Tendencies of change in seasonal temperature- related climate extremes are demonstrated. "Cold" extremes have become less frequent and less severe than in the past, while “warm” extremes have become more frequent and more severe. Moreover, the interval of the occurrence of frost has been decreasing, while the interval of the occurrence of hot days has been increasing. However, many changes are not statistically significant, since the variability of temperature indices at the Potsdam station has been very strong.

15

An automatic hybrid method for retinal blood vessel extraction

Yang Y., Huang S., Rao N.

International Journal of Applied Mathematics and Computer Science

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2008

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Vol. 18, no 3

399-407

EN

The extraction of blood vessels from retinal images is an important and challenging task in medical analysis and diagnosis. This paper presents a novel hybrid automatic approach for the extraction of retinal image vessels. The method consists in the application of mathematical morphology and a fuzzy clustering algorithm followed by a purification procedure. In mathematical morphology, the retinal image is smoothed and strengthened so that the blood vessels are enhanced and the background information is suppressed. The fuzzy clustering algorithm is then employed to the previous enhanced image for segmentation. After the fuzzy segmentation, a purification procedure is used to reduce the weak edges and noise, and the final results of the blood vessels are consequently achieved. The performance of the proposed method is compared with some existing segmentation methods and hand-labeled segmentations. The approach has been tested on a series of retinal images, and experimental results show that our technique is promising and effective.

16

Novel statistical approach for segmentation of brain magnetic resonance imaging using an improved expectation maximization algorithm

Yang Y., Huang S.

Optica Applicata

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2006

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Vol. 36, nr 1

125-136

EN

In this paper, an improved expectation maximization (EM) algorithm called statistical histogram based expectation maximization (SHEM) algorithm is presented. The algorithm is put forward to overcome the drawback of standard EM algorithm, which is extremely computationally expensive for calculating the maximum likelihood (ML) parameters in the statistical segmentation. Combining the SHEM algorithm and the connected threshold region-growing algorithm that is used to provide a priori knowledge, a novel statistical approach for segmentation of brain magnetic resonance (MR) image data is thus proposed. The performance of our SHEM based method is compared with those of the EM based method and the commonly applied fuzzy C-means (FCM) segmentation. Experimental results show the proposed approach to be effective, robust and significantly faster than the conventional EM based method.