Wyniki wyszukiwania - BazTech

1

Analysis of the influence on expressway safety of ramps

Hu J. J., Li F., Han B., Yao J.

Archives of Transport

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2017

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Vol. 43, iss. 3

43--51

EN

As the very important parts of the expressway system, on and off ramps have a great effect on the operation effect of expressways. Once congestion occurs at on and off ramps, it will directly affect the safety of the expressway and vehicles. So this paper first analyzes the location design of on ramps, the length and the influences on the expressway running state of off ramp downstream traffic state, and establishes the expressway operation models based at on and off ramps. The expressway operation models include off ramp delay model, on ramp delay model, expressway delay model and side road delay model under the influence of the distance between on and off ramp and traffic volume. At the same time, the paper analyzes the connection between the traffic operation state and traffic safety, and establishes the expressway safety model based on congestion degree. Through simulation verification, the impact of on and off ramp on the security of the expressway is analyzed. In the simulation, safety rank division is simulated to verify and safety index of different safety ranks. Finally the paper concludes that the delay caused by traffic of the on and off ramps can decrease the safety of expressway.

2

Traffic fatalities prediction based on support vector machine

Li T., Yang Y., Wang Y., Chen C., Yao J.

Archives of Transport

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2016

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Vol. 39, iss. 3

21--30

EN

To effectively predict traffic fatalities and promote the friendly development of transportation, a prediction model of traffic fatalities is established based on support vector machine (SVM). As the prediction accuracy of SVM largely depends on the selection of parameters, Particle Swarm Optimization (PSO) is introduced to find the optimal parameters. In this paper, small sample and nonlinear data are used to predict fatalities of traffic accident. Traffic accident statistics data of China from 1981 to 2012 are chosen as experimental data. The input variables for predicting accident are highway mileage, vehicle number and population size while the output variables are traffic fatality. To verify the validity of the proposed prediction method, the back-propagation neural network (BPNN) prediction model and SVM prediction model are also used to predict the traffic fatalities. The results show that compared with BPNN prediction model and SVM model, the prediction model of traffic fatalities based on PSO-SVM has higher prediction precision and smaller errors. The model can be more effective to forecast the traffic fatalities. And the method using particle swarm optimization algorithm for parameter optimization of SVM is feasible and effective. In addition, this method avoids overcomes the problem of “over learning” in neural network training progress.

3

Effect of Some Variables on the Fibre Packing Pattern in a Yarn Cross-section for Vortex Spun Yarn

Zou Z., Zheng S, Cheng L, Xi B, Yao J.

Fibres & Textiles in Eastern Europe

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2014

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Vol. 22, no. 2 (104)

40--46

EN

This paper examined the influence of various parameters such as fibre fineness, yarn count, distance from the front roller nip point to the hollow spindle, nozzle pressure and yarn delivery speed on the fibre packing pattern in a yarn cross-section for vortex spun yarn. Cross-section images of vortex spun yarns were used to evaluate the fibre packing pattern. Results from different variables influencing the fibre packing pattern for vortex spun yarn were also analysed. The results indicated that the fibre fineness, yarn count, distance from the front roller nip point to the hollow spindle, nozzle pressure and yarn delivery speed are all significant parameters for yarn hairiness and fibre packing density in a vortex spun yarn cross-section.

PL

Badano wpływ grubości włókien, masy liniowej przędzy, odległości przedniej rolki do wydrążonego wrzeciona, ciśnienia w dyszy i szybkości podawania przędzy na upakowanie włókien w przekroju poprzecznym przędzy przędzionej systemem vortex. Zdjęcia przekrojów poprzecznych przędzy zostały wykorzystane dla oceny upakowania włókien. Wyniki analizy rozkładów włókien wykazały, że wszystkie badane parametry mają wydatny wpływ na upakowanie i włochatość w przędzy przędzionej systemem vortex.

4

Low atmospheric density measurement based on Rayleigh scattering of an ultraviolet laser

Wang R, Yao J., Zhong K., Miao Y., Cui H., Zhao X., Miao Y., Zhang C.

Optica Applicata

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2013

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Vol. 43, nr 3

597--605

EN

The qualitative measurement of low atmospheric density in the air flow field has been investigated in this paper. The supersonic flow field with Mach number of 1.5 around the NACA0006 aerofoil has been numerically simulated and the transient slight pressure and low density atmosphere have been experimentally determined based on Rayleigh scattering of a 266 nm ultraviolet laser. The scattering patterns have been effectively captured under different atmospheric pressure of 4.5, 92, 470 and 710 Pa with laser energy of only 0.5 mJ. It has been demonstrated that in the pressure range from 4.5 to 1100 Pa, corresponding to the atmospheric density from 4.8105×10–5 kg/m3 to 1.279×10–2 kg/m3, the scattering intensity of an ultraviolet laser is linear to the pressure and density with the slope coefficient of 0.00968 a.u./Pa and 0.83226 a.u./(kg/m3×10–3). It has been proved that Rayleigh scattering is a promising technology for observation of instantaneous and multidimensional distribution of a supersonic flow field.

5

Interference effect in a dual microresonator-coupled Mach-Zehnder interferometer

Lu Y., Huang X., Fu X., Wen W., Yao J.

Optica Applicata

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2012

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Vol. 42, nr 1

23-29

EN

We present a theoretical study of interference effect in a Mach-Zehnder interferometer in which two microresonators are side coupled to both arms of the interferometer. The results show that sharp asymmetric Fano resonance, coupled resonator induced transparency and absorption effects can be created in such a structure. We demonstrate that these effects arise from interference between a resonance mode and a continuing propagating mode with asymmetric phase difference, destructive interference between two overcoupled resonance modes, and constructive interference between an overcoupled resonance mode and an undercoupled mode or a continuing propagating mode with symmetric phase differences, respectively. These effects may offer a better understanding of the analogous effects in atomic medium and also make optical resonators a potential device to utilize these effects.

6

A surface-plasmon-resonance sensor based on photonic-crystal-fiber with large size microfluidic channels

Bing P., Yao J., Lu Y., Li Z.

Optica Applicata

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2012

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Vol. 42, nr 3

481-491

EN

A surface-plasmon-resonance (SPR) sensor based on photonic-crystal-fiber (PCF) with large size microfluidic channels is proposed. The size of the microfluidic channels with gold coating can be enlarged by reducing the number of the holes in the second layer, so the structure of the PCF is simple and easy to manufacture. It is propitious for metal coating and infiltration of microfluidic. The contact area of sample and metal film is increased, and the interface is closer to the core, so the energy coupling between the plasmon mode and the core-guided mode is easier. Numerical results indicate that the excitation of the plasmon mode is sensitive to the change of the refractive index of adjacent analyte. Sensitivity of the sensor is comparable to the ones of the best existing waveguide sensors. The amplitude resolution is demonstrated to be as low as 3.3×10-5 RIU, and the spectral resolution is 5×10-6 RIU (where RIU means the refractive index unit). The refractive index of microfluidic can be measured effectively.

7

Surface plasmon resonance sensor based on photonic crystal fiber filled with silver nanowires

Fu X., Lu Y., Huang X., Hao C., Wu B., Yao J.

Optica Applicata

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2011

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Vol. 41, nr 4

941--951

EN

Silver nanowire filled photonic crystal fibers are proposed in this paper to achieve surface plasmon resonance sensors and overcome the complicacy and difficulty of coating the holes in the photonic crystal fiber. Optical field distributions of these fibers at different wavelengths are calculated and simulated using the finite element method (FEM), and the sensing properties are discussed in both areas of resonant wavelength and intensity detection. Numerical simulation results show that carefully designed structure of the sensor brings about an excellent effect, with both spectral and intensity sensitivity in the range of 4×10-5-5×10-5 RIU, better than in the case of similar structures coated with metal film, and the fabrication is expected to be simplified.