Wyniki wyszukiwania - BazTech

1

Feasibility study on the submerged floating tunnel in Qiongzhou Strait, China

Jiang B., Liang B., Wu S.

Polish Maritime Research

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2018

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S 2

4--11

EN

Abstract: Currently, one of the challenging tasks for Chinese engineering community is to construct a water-way crossing of Qiongzhou Strait in the south of China. This project has also gained significant attention from researchers in academia. The study presented herein is centered on providing a feasible solution for ac-complishing the above mentioned task. Initially, different alternatives as the best location, judged on the basis of the environmental constraints, are studied. Then the comparison between various structural solutions such as suspension bridge, submarine tunnel and SFT is presented. Among these solutions, SFT appears to be a very suitable alternative for Qiongzhou Strait waterway crossing due to distinctive advantages, like shorter distance, lower cost, less impact on environment and navigation, etc. Based on the appropriate conception for cross sections, support systems, materials, joints and connection schemes, a numerical model is developed by means of the FEM software ANSYS/Fluent. It is then analyzed under the influence of different environmental loading conditions, varying the wave heights and lengths, current velocities and water depths, which are typical in Qiongzhou Strait. The numerical results reveal that the proposed SFT solution performs safely even under extreme weather conditions.

2

Three-dimensional discrete element method simulation of core disking

Wu S., Wu H., Kemeny J.

Acta Geophysica

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2018

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Vol. 66, no. 3

267--282

EN

The phenomenon of core disking is commonly seen in deep drilling of highly stressed regions in the Earth’s crust. Given its close relationship with the in situ stress state, the presence and features of core disking can be used to interpret the stresses when traditional in situ stress measuring techniques are not available. The core disking process was simulated in this paper using the three-dimensional discrete element method software PFC3D (particle flow code). In particular, PFC3D is used to examine the evolution of fracture initiation, propagation and coalescence associated with core disking under various stress states. In this paper, four unresolved problems concerning core disking are investigated with a series of numerical simulations. These simulations also provide some verification of existing results by other researchers: (1) Core disking occurs when the maximum principal stress is about 6.5 times the tensile strength. (2) For most stress situations, core disking occurs from the outer surface, except for the thrust faulting stress regime, where the fractures were found to initiate from the inner part. (3) The anisotropy of the two horizontal principal stresses has an effect on the core disking morphology. (4) The thickness of core disk has a positive relationship with radial stress and a negative relationship with axial stresses.

3

Investigation of low-sidelobe beampattern controlling methods for acoustic transmitting array of underwater vehicles

He Z., Shi Q., Wu S.

Polish Maritime Research

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2017

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S 2

103--110

EN

In underwater unmanned vehicles, complex acoustic transducer arrays are always used to transmitting sound waves to detect and position underwater targets. Two methods of obtaining low-sidelobe transmitting beampatterns for acoustic transmitting arrays of underwater vehicles are investigated. The first method is the boundary element model optimization method which used the boundary element theory together with the optimization method to calculate the driving voltage weighting vector of the array. The second method is the measured receiving array manifold vector optimization method which used the measured receiving array manifold vectors and optimization method to calculate the weighting vector. Both methods can take into account the baffle effect and mutual interactions among elements of complex acoustic arrays. Computer simulation together with experiments are carried out for typical complex arrays. The results agree well and show that the two methods are both able to obtain a lower sidelobe transmitting beampattern than the conventional beamforming method, and the source level for each transmitting beam is maximized in constraint of the maximum driving voltage of array elements being constant. The effect of the second method performs even better than that of the first method, which is more suitable for practical application. The methods are very useful for the improvement of detecting and positioning capability of underwater unmanned vehicles.

4

Different Patterns of Changes in Foliar Carbon Isotope Composition Along Altitude

He Z., Zhan S., Wang W., Hu L., Wu S.

Polish Journal of Ecology

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2017

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Vol. 65, nr 2

227--235

EN

Three types of alpine plant species, Carex montis-everestii, Quercus aquifolioides and Stipa capillacea, along an altitudinal gradient of 3005-5025 m on the Tibetan Plateau, were chosen to test the generality of the hypothesis that foliar carbon isotope composition (δ13C) of C3 plants increases significantly with altitude and to determine climate drivers shaping its altitudinal pattern. Temperature and relative humidity showed significantly negative correlations with altitude; however, precipitation and soil water potential remained unchanged with altitude. Foliar δ13C of C. montis-everestii, Q. aquifolioides, S. capillacea alone or combined together did not significantly increase with altitude, which does not support the leading hypothesis of increased foliar δ13C with altitude. There was no difference in foliar δ13C among all three species. Multi-factor correlation analyses showed that temperature, precipitation and relative humidity alone did not affect foliar δ13C of C. montis-everestii and S. capillacea, but conferred significant effects on foliar δ13C of Q. aquifolioides.

5

Generalized integrated importance measure for system performance evaluation: application to a propeller plane system

Dui H., Chen L., Wu S.

Eksploatacja i Niezawodność

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2017

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Vol. 19, no. 2

279--286

PL

Miara zintegrowanej ważności (IIM) pozwala oceniać szybkość zmian wydajności systemu powstałych w wyniku przejścia elementu systemu z jednego stanu do drugiego. IIM pozwala rozważać scenariusze, w których szybkość przejścia elementu z jednego stanu do drugiego jest stała. Jest to jednak sprzeczne z założeniem degradacji, zgodnie z którym wydajność systemu obniża się, w związku z czym, szybkość przejścia może z upływem czasu ulegać zwiększeniu. Rozkład Weibulla opisuje żywotność danego elementu, co wykorzystuje się w wielu różnych zastosowaniach technicznych do modelowania złożonych zbiorów danych. W przedstawionej pracy, rozszerzono IIM uzyskując nową miarę ważności, która pozwala rozważać scenariusze, w których szybkość przejścia elementu z jednego stanu do drugiego w wyniku degradacji jest zależną od czasu funkcją rozkładu Weibulla. Przyjęto, że warunkowy rozkład prawdopodobieństwa elementu przebywającego w pewnym stanie jest rozkładem Weibulla, gdzie dany jest kolejny stan do którego ma przejść dany element. Badania nad nową miarą ważności umożliwiają identyfikację najważniejszych elementów podczas trzech różnych okresów czasu życia systemu, co odpowiada charakterystyce rozkładów Weibulla. Dla ilustracji, wyprowadzono pewne właściwości probabilistyczne i zastosowano rozszerzoną miarę ważności do analizy przykładu rzeczywistego układu śmigłowca.

EN

The integrated importance measure (IIM) evaluates the rate of system performance change due to a component changing from one state to another. The IIM simply considers the scenarios where the transition rate of a component from one state to another is constant. This may contradict the assumption of the degradation, based on which system performance is degrading and therefore the transition rate may be increasing over time. The Weibull distribution describes the life of a component, which has been used in many different engineering applications to model complex data sets. This paper extends the IIM to a new importance measure that considers the scenarios where the transition rate of a component degrading from one state to another is a time-dependent function under the Weibull distribution. It considers the conditional probability distribution of a component sojourning at a state is the Weibull distribution, given the next state that component will jump to. The research on the new importance measure can identify the most important component during three different time periods of the system lifetime, which is corresponding to the characteristics of Weibull distributions. For illustration, the paper then derives some probabilistic properties and applies the extended importance measure to a real-world example (i.e., a propeller plane system).

6

Automatic parameters selection of Gabor filters with the imperialism competitive algorithm with application to retinal vessel segmentation

Farokhian F., Yang C., Demirel H., Wu S., Beheshti I.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 1

246--254

EN

Retinal images play an important role in the early diagnosis of diseases such as diabetes. In the present study, an automatic image processing technique is proposed to segment retinal blood vessels in fundus images. The technique includes the design of a bank of 180 Gabor filters with varying scale and elongation parameters. Furthermore, an optimization method, namely, the imperialism competitive algorithm (ICA), is adopted for automatic parameter selection of the Gabor filter. In addition, a systematic method is proposed to determine the threshold value for reliable performance. Finally, the performance of the proposed approach is analyzed and compared with that of other approaches on the basis of the publicly available DRIVE database. The proposed method achieves an area under the receiver operating characteristic curve of 0.953 and an average accuracy of up to 0.9392. Thus, the results show that the proposed method is well comparable with alternative methods in the literature.

7

Mechanical Properties of Magnesium Alloys Produced by the Heated Mold Continuous Casting Process

Okayasu M., Wu S., Tanimoto T., Takeuchi S.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

208--216

EN

Investigation of the tensile and fatigue properties of cast magnesium alloys, created by the heated mold continuous casting process (HMC), was conducted. The mechanical properties of the Mg-HMC alloys were overall higher than those for the Mg alloys, made by the conventional gravity casting process (GC), and especially excellent mechanical properties were obtained for the Mg₉₇Y₂Zn₁-HMC alloy. This was because of the fine-grained structure composed of the α-Mg phases with the interdendritic LPSO phase. Such mechanical properties were similar levels to those for conventional cast aluminum alloy (Al_84.7Si_10.5Cu_2.5Fe_1.3Zn₁ alloys: ADC12), made by the GC process. Moreover, the tensile properties (σ and ε_f) and fatigue properties of the Mg₉₇Y₂Zn₁-HMC alloy were about 1.5 times higher than that for the commercial Mg₉₀Al₉Zn₁-GC alloy (AZ91). The high correlation rate between tensile properties and fatigue strength (endurance limit: σ_l) was obtained. With newly proposed etching technique, the residual stress in the Mg₉₇Y₂Zn₁ alloy could be revealed, and it appeared that the high internal stress was severely accumulated in and around the long-period stacking-order phases (LPSO). This was made during the solidification process due to the different shrinkage rate between α-Mg and LPSO. In this etching technique, micro-cracks were observed on the sample surface, and amount of micro-cracks (density) could be a parameter to determine the severity of the internal stress, i.e., a large amount to micro-cracks is caused by the high internal stress.

8

A new simple local muscle recovery model and its theoretical and experimental validation

Ma L., Zhang W., Wu S., Zhang Z.

International Journal of Occupational Safety and Ergonomics

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2015

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Vol. 21, No. 1

86--93

EN

This study was conducted to provide theoretical and experimental validation of a local muscle recovery model. Muscle recovery has been modeled in different empirical and theoretical approaches to determine work-rest allowance for musculoskeletal disorder (MSD) prevention. However, time-related parameters and individual attributes have not been sufficiently considered in conventional approaches. A new muscle recovery model was proposed by integrating time-related task parameters and individual attributes. Theoretically, this muscle recovery model was compared to other theoretical models mathematically. Experimentally, a total of 20 subjects participated in the experimental validation. Hand grip force recovery and shoulder joint strength recovery were measured after a fatiguing operation. The recovery profile was fitted by using the recovery model, and individual recovery rates were calculated as well after fitting. Good fitting values (r2 > .8) were found for all the subjects. Significant differences in recovery rates were found among different muscle groups (p < .05). The theoretical muscle recovery model was primarily validated by characterization of the recovery process after fatiguing operation. The determined recovery rate may be useful to represent individual recovery attribute.

9

Evaluation of the biocompatibility of a hydroxyapatite-CaTiO3 coating in vivo

Wu S., Tu B., Lin J., Wang Z., Wang X., Shen M., Hu R.

Biocybernetics and Biomedical Engineering

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2015

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Vol. 35, no. 4

296--303

EN

Objective: This study was designed to evaluate the biocompatibility and osteointegrative activity of hydroxyapatite (HA)-CaTiO3, titanium substrate, traditional HA coating and CaTiO3 coating via an animal experiment. Method: Four types of screws (type 1: coated with HA; type 2: coated with CaTiO3; type 3: coated with HA-CaTiO3; type 4: untreated titanium screws) were implanted into femur bone of 48 New Zealand rabbits. Histological and mechanical investigations were employed at the end of 2, 4, 8 and 12 weeks to evaluate the material osteointegration. Results: (1) All of the experimental rabbits were healthy during the experiment process. (2) Histological investigation showed fully regenerated and well integrated bone tissue surrounding the screws coated with HA, HA-CaTiO3 and CaTiO3. (3) Mechanical investigation showed that the bonding strength of HA-CaTiO3 coating was significantly higher than that of CaTiO3 coating or titanium materials without coating, but was lower than those coated with HA. Conclusion: HA-CaTiO3 coating possesses similar admirable biocompatibility and osteointegration activity with HA coating, indicating a promising coating material for implants in orthopedics.

10

Monocular Vision-based Sensor for Autonomous Mobile Robot Localization by Circular Markers

Lu J., Shi J., Wu S.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1b

131--133

EN

To navigate reliably in indoor environments, a mobile robot must know where it is. This paper is concerned with the design of a monocular vision-based algorithm for on-line estimation of a mobile robot’s location using circular markers. The algorithm is based on 3-D analytic geometry, which is capable of estimating both the orientation and the position of the camera by a single camera image. The method can be used for camerarobot calibration for eye-on-hand systems, and autonomous mobile robot guidance. Laboratory experiments using a moving cylindrical object demonstrate both the accuracy and stability of the method.

PL

Robot mobilny, aby wiarygodnie nawigować we wnętrzu, musi znać swoje położenie. Opracowanie, w celu oszacowania bieżącego położenia robota, koncentruje się na projekcie algorytmu opartego o obraz jedno-okularowy, z zastosowaniem markerów kołowych. Algorytm przeprowadza analizę w geometrii 3D, co umożliwia oszacowanie zarówno orientacji jak i położenia kamery na podstawie danych obrazu z jednej kamery. Metoda może być zastosowana do kalibracji robota-kamery w systemie oko-ręka i do sterowania autonomicznym robotem mobilnym. Zademonstrowano eksperymenty laboratoryjne z wykorzystaniem obiektu cylindrycznego, analizując zarówno dokładność jak i stabilność metody.

11

Transfer characteristic shift technique for full input range In pipelined ADCs with background calibration

Ning N., Sui Z., Chen H., Xu S., Zhang S., Zheng J., Wu S., Yu Q.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 11a

214-2017

EN

A transfer characteristic shift technique has been proposed in this paper. By shifting the transfer characteristic of the sub-stage under calibration in pipelined ADC, a full input range is realized for pipelined ADC with background calibration. Pseudorandom sequence (PN) signal with maximum amplitude of Vref/4 can be injected into the multiplying digital-to-analog converter (MDAC) which speeds up the convergence process. Simulation results shows that the technique can achieve full input range and fast convergence speed simultaneously with small hardware cost In pipelined ADCs with PN signal based background calibration.

PL

W artykule przedstawiono metodę przesunięcia charakterystyki przesyłu potokowych przetworników analogowo-cyfrowych. Badania symulacyjne dowodzą, że proponowana technika pozwala na wykorzystanie pełnego zakresu wejściowego przetwornika oraz szybką konwergencję, przy niewielkich wymaganiach sprzętowych.

12

System Dynamic Model of Risk Element Transmission in Project Chain

Li C., Lu G., Ma P., Wu S.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 7b

308--310

EN

It is important to realize that the risk of one project will affect other projects as well. Based on risk element transmission theory, firstly, this paper established a risk element transmission model between two projects by using system dynamics methodology. And then this paper stimulated the variations of the risk element transmission impact when the owner and the contractor hold different risk-sharing ratios. The simulation results indicate that the transmission impact of risk element will enjoy an accelerated growth with the increase of the contractor’s risk-sharing ratio.

PL

W artykule analizuje się możliwość przenoszenia ryzyka między różnymi projektami. Wprowadzono pojęcie współczynnika przenoszenia ryzyka.

13

Generation of Electronic Nautical Chart Data for Assessment of Navigational Safety in Harbour and Waterway Design

Guan K., Shi C., Wu S., Xu T.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2010

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Vol. 4, no. 1

17--22

EN

Navigational simulator is widely applied in the assessment of Navigational Safety in the harbour and waterway design. According to the needs of ENC(Electronic Nautical Chart) data in the navigational assessment, this paper analyzes the source of ENC data, such as S-57 data, MVCF(Military Vector Chart Format) data and CAD(Computer Aided Design) data. An effective method of ENC data generation has been developed. Special techniques are investigated for generating ENC data, such as ENC data structure design-ing, chart data conversion, digitization method of raster images of CAD design drawing, optimization ap-proaches and data integration methods. Software has been developed to edit the chart data with good perfor-mance. The technologies developed in this paper have been applied to more than 100 practical projects and successful results have been obtained.

14

Design of the state predictive model following control system with time-delay

Wang D., Wu S., Okubo S.

International Journal of Applied Mathematics and Computer Science

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2009

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Vol. 19, no 2

247-254

EN

Time-delay systems exist in many engineering fields such as transportation systems, communication systems, process engineering and, more recently, networked control systems. It usually results in unsatisfactory performance and is frequently a source of instability, so the control of time-delay systems is practically important. In this paper, a design of the state predictive model following control system (PMFCS) with time-delay is discussed. The bounded property of the internal states for the control is given, and the utility of this control design is guaranteed. Finally, examples are given to illustrate the effectiveness of the proposed method, and state predictive control techniques are applied to congestion control synthesis problems for a TCP/AQM network.

15

Rapid determination of loratadine in medicine and bio-fluids using a myoglobin-luminol chemiluminescence system

Wang Z., He X., Wu S., Song Z.

Chemia Analityczna

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2009

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Vol. 54, No. 3

471-481

EN

A sensitive chemiluminescence method for determination of loratadine has been presented. The method is based on the inhibitory effect of loratadine on the chemiluminescence reaction between luminol and myoglobin. The decrement in chemiluminescence intensity changed linearly with the logarithm of loratadine concentration over the range 0.1 -100.0 ng mL-1(R-1 = 0.9992) with a detection limit of 0.03 ng L-1(3&sigma). At a flow rate of 2.0 mL min-1, the complete analytical process could be performed within 30 s including sampling and washing, with a relative standard deviation of less than 3.0% (n = 7). Without any pretreat-ment the proposed procedure was applied to the determination of loratadine in tablets, human serum, and urine samples with recoveries of 91.7-108.3%, 90.1-103.3%, and 94.6-107.6%, respectively.

PL

Przedstawiono czułą chemiluminescencyjną metodę oznaczania loratadyny. W metodzie wykorzystano hamujące działanie loratadyny na chemiluminescencję powstającą podczas reakcji między luminolem i mioglobiną. Natężenie chemiluminescencji zmniejszało się liniowo wraz ze wzrostem logarytmu stężenia loratadyny w zakresie 0,1-100 ng mL2 (R2 = 0,9992), a granica wykrywalności wynosiła 0.03 ng mL2 (3σ). Przy przepływie 2,0 mL min~' kompletne oznaczenie mogło być wykonane w ciągu 30 s (włączając próbkowanie i przemywanie), przy czym względne odchylenia standardowe wynosiło mniej niż 3% (n = 7). Metodę zastosowano do oznaczania loratadyny w tabletkach, we krwi ludzkiej i w moczu, bez wstępnego przygotowania; odzysk wynosił odpowiednio: 91,7-108,3%, 90, l-l 03,3% oraz 94,6-107,6%.