Evaluation of Bus Vibration Comfort Based on Passenger Crowdsourcing Mode

Vibration comfort is an important factor affecting the quality of service (QoS) of bus. In order to make people involved in supervising bus’s vibration comfort and improve passengers’ riding experience, a novel mode of passenger crowdsourcing is introduced. In this paper, comfort degree of bus vibration is calculated from bus’s vibration signals collected by passengers’ smartphones and sent through WiFi to the Boa web server which shows the vibration comfort on the LCD deployed in bus and maybe trigger alarm lamp when the vibration is beyond the threshold. Three challenges here have been overcome: firstly, space coordinate transformation algorithm is used to solve the constant drift of signals collected; secondly, a low-pass filter is designed to isolate gravity from signals real-timely via limited computing resources; thirdly, an embedded evaluation system is developed according to the calculation procedure specified by criterion ISO 2631-1997. Meanwhile, the model proposed is tested in a practical running environment, the vibration data in whole travel are recorded and analyzed offline. The results show that comfort degree of vibration obtained from the experimental system is identical with the truth, and this mode is proved to be effective.

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MTF Compensation Combining Reciprocal Cell with Shift Invariance Wavelet

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.48-49.719 ◽

2011 ◽

Vol 48-49 ◽

pp. 719-723

Author(s):

Zhao Jun Liu ◽

Zhi Zhang ◽

De Shen Xia

Keyword(s):

Cutoff Frequency ◽

Band Pass Filter ◽

Test Results ◽

Pass Filter ◽

Low Pass Filter ◽

Low Pass ◽

Shift Invariance ◽

Band Pass ◽

Better Than

On remote sensing imaging platform, quality of image is normally degraded by aliasing. The low-pass filter is commonly used to dealiasing. However low-pass filter introduces error for frequencies above its cutoff frequency. And the removed aliasing is also valuable information. To retain the valuable information, we propose a restoration based on band-pass filter. Firstly, the image is transformed into frequency domain. A restoration of reciprocal cell is adopted. It is based on geometrical characteristics of sensors. As a result, the superposition parts are separated from spectrum inside the bandwidth. Then aliasing spectrum is put into right position. Inverse filter is used to deblurring and remove the color noise. Finally, the shift invariance wavelet is combined to reduce the white noise. The test results indicate that the proposed restoration is better than conventional restorations. Valuable information of the restored spectrum is more than degraded spectrum. So this proposed method will be beneficial in the field of practical projects.

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Improvement of tomographic reconstruction in bone SPECT

Nuklearmedizin ◽

10.1055/s-0038-1623932 ◽

2006 ◽

Vol 45 (01) ◽

pp. 35-40 ◽

Cited By ~ 1

Author(s):

G. Heidrich ◽

C.O. Sahlmann ◽

U. Siefker ◽

H. Luig ◽

C. Werner ◽

...

Keyword(s):

Iterative Algorithm ◽

Iterative Reconstruction ◽

Wiener Filter ◽

Filtered Backprojection ◽

Maximal Interval ◽

Pass Filter ◽

Low Pass Filter ◽

Low Pass ◽

Bone Spect

Summary Aim: The comparison between iterative reconstruction and filtered backprojection in the reconstruction of bone SPECT in the diagnosis of skeletal metastases. Patients, methods: 47 consecutive patients (vertebral segments: n = 435), with suspected malignancy of the vertebral column, were examined by bone scintigraphy and MRI (maximal interval between the two procedures ± 5 weeks). The SPECT-data were reconstructed with an iterative algorithm (ISA) and with filtered backprojection. We defined semiquantitative criteria in order to assess the quality of the tomograms. Conventional reconstruction was performed both by a Wiener-filter and a low-pass-filter. Iterative reconstruction was performed by the ISA algorithm. The clinical evaluation of the different reconstruction algorithms was performed by MRI as the gold-standard. Results: Sensitivity (%): 87.3 (ISA), 86.4 (low-pass), 79.7 (Wiener); specificity (%): 95.3 (ISA), 95 (low-pass), 85.4 (Wiener). The sensitivity of iterative reconstructed SPECT and low-pass reconstructed SPECT was significantly higher (p <0.05) compared with the sensitivity of SPECT reconstructed by the Wiener-filter. The specificity of iterative reconstruction ISA and low-pass-filter reconstructed SPECT were significantly higher compared with the SPECT data reconstructed by the Wiener-filter. ISA was significantly superior to the Wiener- SPECT relating to all criteria of quality. Iterative reconstruction was significantly superior to the low-pass-SPECT relating to 2 of 3 criteria. In addition the Wiener-SPECT was significantly inferior to the low-pass-SPECT regarding to 2 of 3 criteria. Conclusion: In our series the iterative algorithm ISA was the method of choice in the reconstruction of bone SPECT data. In comparison with conventional algorithms ISA offers a significantly higher quality of the tomograms and yields a high diagnostic accuracy.

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Enhancing the abilities in assessing slurry pumps' performance degradation and estimating their remaining useful lives by using captured vibration signals

Journal of Vibration and Control ◽

10.1177/1077546315604522 ◽

2015 ◽

Vol 23 (12) ◽

pp. 1925-1937 ◽

Cited By ~ 14

Author(s):

Peter W Tse ◽

Dong Wang

Keyword(s):

State Space ◽

State Space Model ◽

Performance Degradation ◽

Health Indicator ◽

Pass Filter ◽

Low Pass Filter ◽

Vibration Signals ◽

Space Model ◽

Low Pass ◽

Nonlinear State

Slurry pumps are widely used to transport abrasive slurry that contains oil and sands. Because of the abrasive nature, the impellers inside the pumps wear easily. Severe impeller wear may cause unexpected pump failure that leads to substantial oil production loss. To assess the impeller performance degradation and then estimate its remaining useful life (RUL), an efficient prognostic method has been designed. For assessing the impeller performance degradation, statistical features were extracted from vibration signals collected from on-site operating slurry pumps. Their corresponding frequency spectra were generated after the vibration signals were processed by a low-pass filter. Here, the low-pass filter aims to retain impeller-related vibration components, such as the pump vane-passing frequency and its harmonics. Principal component analysis was then applied to reduce the dimensionality of the extracted statistical features to one dimensionality, which was used to construct a health indicator to reflect the health evolution of the impeller over time. For estimating the impeller's RUL, a nonlinear state space model was designed to track its temporal health indicator. An efficient unscented transform method was employed to iteratively estimate the joint posterior probability density function of the parameters of the nonlinear state space model. After the proper nonlinear state space model had been determined, extrapolations of the nonlinear state space model to a specified alert threshold were used to estimate the impeller's RUL. Vibration signals captured from on-site operating slurry pumps were used to verify the effectiveness of the proposed prognostic method. The results show that prediction accuracy of the estimated RULs have been improved as compared to those generated by other recently developed slurry pump prognostic methods. Moreover, the more the temporal vibration data is available, the better the performance of the state space model; hence, the higher the accuracy in predicting the impeller's RUL.

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Analysis and Suppression of High-Frequency Harmonics of High Power Photovoltaic Inverter System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.556-562.1573 ◽

2014 ◽

Vol 556-562 ◽

pp. 1573-1576

Author(s):

Pei Deng ◽

You Xin Yuan ◽

Liang Yuan ◽

Ping Kuang ◽

Jing Chen

Keyword(s):

High Power ◽

High Frequency ◽

Electric Energy ◽

Photovoltaic System ◽

Pass Filter ◽

Low Pass Filter ◽

Result Show ◽

Low Pass ◽

Energy Grid

According to the growing need for renewable energy. Grid-connected photovoltaic system is used in many territories. To suppress the high-frequency harmonics of high power photovoltaic inverter, a LC low pass filter (LPF) has been proposed in this paper. The following have been done in the study: analysis of the high power photovoltaic inverter system and its harmonics, method of high-frequency harmonics suppression, and simulation of high-frequency harmonics suppression. According to the normalization method, the parameters of LPF are calculated. Then the parameters are put into a simulation model. The simulation result show that THD is 7.26%. It is much less than the former 78.19%. So it can be widely used in power system to suppress the high-frequency and to ensure the quality of electric energy.

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Toward Improvement of Resistance Testing Reliability

Journal of Engineering and Technological Sciences ◽

10.5614/j.eng.technol.sci.2021.53.2.1 ◽

2021 ◽

Vol 53 (2) ◽

pp. 210201

Author(s):

I. K.A.P. Utama ◽

Dian Purnamasari ◽

I Ketut Suastika ◽

Nurhadi Nurhadi ◽

Giles Thomas

Keyword(s):

Test Performance ◽

Resistance Testing ◽

Pass Filter ◽

Low Pass Filter ◽

Testing Procedures ◽

Benchmark Tests ◽

Low Pass ◽

Resistance Data ◽

Track Test

. Periodically conducting a benchmark test with estimated uncertainty is important to improve the quality of resistance predictions and understand the influence of instrumentation, testing procedures and analysis techniques. The LHI-007 Ro-Ro Ferry ship model, made available by the Maritime Research Institute Netherlands (MARIN), was used for benchmark testing from 2010 to 2018 at the Indonesian Hydrodynamic Laboratory. Comparisons were made between filtering the resistance data with a low-pass filter and with a Kalman filter. This work shows how benchmark tests can be used to track test performance over a longer period and proposes techniques to improve the uncertainty in the resistance results.

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