In this paper we discuss the relation and distin ction between 3D objec t recognition and gray image recognition, analyze position and pose of the 3D ob ject influence on range data and describe problem of the 3D object recognition w ith mathematical method. We also generally introduce current 3D object recogniti on methods and key technologies.
Pumping stations are important regulation facilities in a water distribution system. Intake structures can generally have a great influence on the operational state of the pumping station. To analyze the effects of the bell mouth height of the two-way intake on the performance characteristics and the pressure pulsations of a two-way pumping station, the laboratory-sized model pump units with three different intakes were experimentally investigated. To facilitate parameterized control, ellipse and straight lines were used to construct the profile of the bell mouth. The frequency domain and time-frequency domain of the pressure pulsations on the wall of intakes were analyzed by the Welch’s power spectral density estimate and the continuous wavelet transform (CWT) methods, respectively. The results showed that the bell mouth height (H) has significant influences on the uniformity of the impeller inflow and the operation stability of the pump unit. When H = 204 mm, the data fluctuated greatly throughout the test process and the performance curves are slightly lower than the other two schemes. As the bell mouth height gradually decreases, the average pressure difference of each measuring point began to decrease, more homogeneous velocity distribution of impeller inflow can be ensured. The amplitude of blade passing frequency is obvious in the spectrum. While when (H) is more than 164 mm, the main frequency of pressure pulsations at three points fluctuates with the rotation of the impeller. When H decreases to 142 mm, pressure pulsations will be independent of the operating conditions and positions which contributes to the long-term stable operation of the pump unit.
Spectrum based water quality analyzer for comprehensive organic pollution index evaluating is a kind of green measurements with prosperous futures. Due to the low estimation precision of single-spectrum based analyzer and the complementary advantages of multi-spectrums, a modeling method based on information fusion of the ultra-violet absorption spectrum and the fluorescence emission spectrum is adopted for rapid measure of organic pollution indices such as COD, TOC, etc. A module structure is designed for portable realization to perform the field mobile tasks and rapid scene measurements. The experimental results show that this instrument possesses a better prediction capability than single UV based instruments popular in the market.
Taking into account various factors that may influence the groundwater specific vulnerability,including topography,strata,hydrogeology and human activities,this paper selected 9 indices from these factors,and constructed nonlinear fuzzy membership with method of fuzzy comprehensive evaluation.The membership degrees of these indices were calculated,then the groundwater specific vulnerability in Guangzhou was assessed combining with the GIS technology of spatial analysis.The results indicate that the indices of special vulnerability change in the range of 2.99-22.16,and could be divided into 5 grades.It comes to the conclusion that the groundwater in Guangzhou is easily polluted,and there are much obvious regional differences.It is necessary to take different protecting measures to promote sustainable utilization of groundwater resources in Guangzhou.
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