Concrete filled tubular arch bridge was widely used in China.The large dead weight and non-integrity of prestressed concrete deck above the arch went against the durability and bridge seismic design.Modified verbundfertigteil (VFT) was proposed as deck in the arch bridge.Modified VFT girder was convenient to fabricate and was light-weighted.Structural analysis was investigated and it proved that modified VFT was an economic solution.Live loaded structural index (LLSI) was proposed to evaluate the steel bridge's efficiency between different structural schemes.
In B class uncertainty appraisement of electric energy meter verification device,the main factor affecting uncertainty appraisement result is all sorts of error source,using electric energy meter verification device integration as error source substitute each independent error source in measure ment part to analyze the influence of uncertainty appraisement of electric energy meter verification de vice,and through the example explains the method using the demarcating error of alternating current meter verification device to substitute the cumulate error of each measurement part in alternating cur rent meter verification device is feasible.The application result shows that this method can reduce cau lationstepandsimplyanalysismethod.
Electromechanical impedance (EMI) based structural health monitoring methods have been successfully applied to various engineering fields. However, the studies on damage quantification using EMI based techniques are still limited. In general, conventional EMI based methods evaluate the changes in the host structure by comparing the difference between impedance responses from undamaged and damaged structures, with statistical damage indicators, i.e. root mean square deviation (RMSD) and cross correlation. These damage indicators can detect the existence of damage in structures, but are not able to precisely locate and identify the severity of damages. This paper presents experimental validations on a novel structural damage identification approach based on the sensitivity of resonance frequency shifts in the impedance and sparse regularization technique. The coupled finite element model of the piezoelectric transducer and host structure is developed and calibrated for the damage quantification. A limited number of measured resonance frequency shifts are used to identify the damage in a number of segments in the host structure. Experimental verifications are conducted on narrow aluminum plates to demonstrate the accuracy and performance of the presented approach. The identification results demonstrate the effectiveness and performance of using the proposed approach for structural damage localization and quantification. To investigate the capacity of impedance based technique for SHM with the proposed approach, numerical studies are further conducted to discuss the sensitivity range of this method.
Although the empirical mode decomposition (EMD) method is an effective tool for noise reduction in lidar signals, evaluating the effectiveness of the denoising method is difficult. A dual-field-of-view lidar for observing atmospheric aerosols is described. The backscattering signals obtained from two channels have different signal-to-noise ratios (SNRs). The performance of noise reduction can be investigated by comparing the high SNR signal and the denoised low SNR signal without a simulation experiment. With this approach, the signal and noise are extracted to one intrinsic mode function (IMF) by the EMD-based denoising; thus, the threshold method is applied to the IMFs. Experimental results show that the improved threshold method can effectively perform noise reduction while preserving useful sudden-change information.
Luziyuan lead zinc iron metal mining area is located in the south of Baoshan-Zhenkang lead, zinc, mercury, rare metal mineralization belt of the southwest Sanjiang metallogenic belt.According to the mine tunnel drilling and logging data, that the ore bodies are controlled by strata and faults, symbiosis and Dali rock, limestone, near ore wall rock skarnization strongly, the research shows that the deposit belongs to sedimentary transformation - skarn Pb Zn Fe polymetallic deposit. [ Mining area within the range of 1:50000, 1:50000 gravity measurements of soil geochemical survey, combined with the large scale mapping of data discovery lead zinc iron copper resources are expected to find in the eastern Luziyuan area Mangxi - Head Mountain Luojiazhai resource replacement area.
By means of the pressure signals of a certain research engine which has an eight axial stage compressor.A method of time-frequency analysis is presented in the paper.Information on the stall inception and development,which has some correlations with the onset-frequency and stall-frequency can be obtained during the engine operations.Therefore,the two main frequencies at the stall inception can be observed in the time-frequency plots.In order to identify the signal of the onset of stall accurately,this paper introduces the technique of the wavelet analysis,and provides an example of the 1st-6th compressor stage signals which are decomposed by Daubechies wavelets.The result indicates that different frequencies show different stall inception prior to the stage stall,and proves the singularity of the signal of stall.The stage of the first stall is ascertained by this method in the paper.
High-quality estimation of surface normal can help reduce ambiguity in many geometry understanding problems, such as collision avoidance and occlusion inference. This paper presents a technique for estimating the normal from 3D point clouds and 2D colour images. We have developed a transformer neural network that learns to utilise the hybrid information of visual semantic and 3D geometric data, as well as effective learning strategies. Compared to existing methods, the information fusion of the proposed method is more effective, which is supported by experiments. We have also built a simulation environment of outdoor traffic scenes in a 3D rendering engine to obtain annotated data to train the normal estimator. The model trained on synthetic data is tested on the real scenes in the KITTI dataset. And subsequent tasks built upon the estimated normal directions in the KITTI dataset show that the proposed estimator has advantage over existing methods.
Time-frequency analysis of structural vibration responses provides essential information for structural system identification, modal updating, and condition assessment. However, spurious peaks introduced by the strong noise will significantly increase the false positive rate as well as compromise the sparse time-frequency signal representation. This paper proposes a high-resolution time-frequency representation approach for nonstationary signals polluted with strong noise. With a high sensitivity to detect slight frequency shift and an immunity to noise effect, the intermittent chaotic of Duffing oscillator system is introduced to accurately identify the time-varying instantaneous frequencies. Furthermore, an adaptive Duffing oscillator array is adopted to improve the instantaneous frequency identification efficiency. The feasibility and effectiveness of the proposed method are verified with numerical and experimental studies. Numerical studies are conducted on a multicomponent synthetic nonstationary signal as well as on a two-story shear building with time-varying stiffness under seismic loads. In experimental validations, the acceleration response of a laboratory bridge model under moving vehicle load is also analyzed by using the proposed approach to obtain the instantaneous frequency variations induced by the bridge–vehicle interaction. These results are compared with those obtained from a method based on empirical wavelet transform and Hilbert transform (EWT-HT), to highlight the superiority of the proposed approach in obtaining high-resolution time-frequency analysis results for nonstationary signals with strong noise.
