Localization is one of the key components in the operation of self-driving cars. Owing to the noisy global positioning system (GPS) signal and multipath routing in urban environments, a novel, ...practical approach is needed. In this study, a sensor fusion approach for self-driving cars was developed. To localize the vehicle position, we propose a particle-aided unscented Kalman filter (PAUKF) algorithm. The unscented Kalman filter updates the vehicle state, which includes the vehicle motion model and non-Gaussian noise affection. The particle filter provides additional updated position measurement information based on an onboard sensor and a high definition (HD) map. The simulations showed that our method achieves better precision and comparable stability in localization performance compared to previous approaches.
Abstract Background context Anterior decompression and fusion (ADF) for ossification of the posterior longitudinal ligament (OPLL) is technically demanding and associated with complications. Although ...various factors affecting clinical outcome have been investigated in posterior decompression, prognostic factors of ADF remain unclear. Purpose The purpose of the study was to identify surgical outcome and prognostic factors of ADF for cervical myelopathy due to OPLL. Study design This was a retrospective case study. Patient sample Between 2005 and 2012, 913 patients underwent decompression surgery for cervical OPLL at our institution. Among them, 131 who underwent ADF and 221 who underwent laminoplasty were enrolled. Inclusion criteria were (1) diagnosis of OPLL; (2) cervical compressive myelopathy; and (3) no trauma, infection, tumor, or previous surgery. We excluded 60 patients with ADF and 157 patients with laminoplasty owing to inadequate follow-up or absence of preoperative myelopathy. Finally, 71 patients with ADF and 64 patients with laminoplasty were enrolled in this study (mean follow-up, 48 vs 41 months). Outcome measures Neurologic assessment was conducted using the Japanese Orthopedic Association (JOA) scoring system for cervical myelopathy. Rate of neurologic improvement was calculated by comparing preoperative and postoperative JOA scores. Methods We investigated the effects of such variables as age, gender, body mass index (BMI), presence of diabetes mellitus (DM), smoking history, type of OPLL, shape of the ossified lesion, occupying ratio of OPLL, presence of intramedullary increased signal intensity (ISI) on magnetic resonance imaging (MRI), and sagittal alignment of the cervical spine on surgical outcome. Severity of ISI was classified into three groups based on T2-weighted sagittal MRI as follows: Grade 0, none; Grade 1, ISI limited to one disc level; or Grade 2, ISI beyond one disc level. This work was supported by the 2013 Korea Health Technology R&D Project of the Ministry of Health and Welfare of the Republic of Korea (A120254). Results In patients with an occupying ratio ≥60% or with presence of ISI on MRI, ADF yielded better surgical outcome than laminoplasty. A higher ISI grade (B=−28.5, p=.000) and a higher occupying ratio (B=0.88, p=.04) were significantly associated with a lower recovery rate (R=0.56, p=.006). Older age also was associated with a lower recovery rate. Gender, BMI, presence of DM, smoking history, type of OPLL, shape of the ossified lesion, and cervical alignment were not associated with recovery rate. Conclusion Anterior decompression and fusion has favorable outcome in patients with an occupying ratio ≥60% or with presence of ISI on MRI. Presence of higher ISI grade, higher occupying ratio, and older age were associated with a poor long-term surgical prognosis. Therefore, evaluating ISI and occupying ratio on preoperative MRI is important for selecting the appropriate surgical approach and for predicting clinical outcome after surgery for cervical compressive myelopathy due to OPLL.
The location of the vehicle is a basic parameter for self-driving cars. The key problem of localization is the noise of the sensors. In previous research, we proposed a particle-aided unscented ...Kalman filter (PAUKF) to handle the localization problem in non-Gaussian noise environments. However, the previous basic PAUKF only considers the infrastructures in two dimensions (2D). This previous PAUKF 2D limitation rendered it inoperable in the real world, which is full of three-dimensional (3D) features. In this paper, we have extended the previous basic PAUKF’s particle weighting process based on the multivariable normal distribution for handling 3D features. The extended PAUKF also raises the feasibility of fusing multisource perception data into the PAUKF framework. The simulation results show that the extended PAUKF has better real-world applicability than the previous basic PAUKF.
Abstract
Recently, the xEV market has been expanding by strengthening regulations on fossil fuel vehicles. It is essential to ensure the safety and reliability of batteries, one of the core ...components of xEVs. Furthermore, estimating the battery’s state of health (SOH) is critical. There are model-based and data-based methods for SOH estimation. Model-based methods have limitations in linearly modeling the nonlinear internal state changes of batteries. In data-based methods, high-quality datasets containing large quantities of data are crucial. Since obtaining battery datasets through measurement is difficult, this paper supplements insufficient battery datasets using time-series generative adversarial network and compares the improvement rate in SOH estimation accuracy through long short-term memory and gated recurrent unit based on recurrent neural networks. According to the results, the average root mean square error of battery SOH estimation improved by approximately 25%, and the learning stability improved by approximately 40%.
Location is one of the most important parameters of a self-driving car. To filter the sensor noise, we proposed the extended particle-aided unscented Kalman filter (PAUKF). Although the performance ...of the PAUKF improved, it still needed parameter tuning as other Kalman filter applications do. The characteristic of noise is important to the filter’s performance; the most important parameters therefore are the variances of the measurement. In most Kalman filter research, the variance of the filter is tuned manually, costing researchers plenty of time and yielding non-optimized results in most applications. In this paper, we propose a method that improves the performance of the extended PAUKF based on the coordinate descent algorithm by learning the most appropriate measurement variances. The results show that the performance of the extended PAUKF improved compared to the manually tuned extended PAUKF. By using the proposed training algorithm, practicability, training time efficiency and the estimation precision of the PAUKF improved compared to previous research.
Abstract Background Context Laminoplasty is a major surgical method used to treat patients with cervical ossification of the posterior longitudinal ligament (OPLL). Sometimes, patients with cervical ...OPLL demonstrate postoperative kyphosis despite sufficient preoperative lordosis. Recently, the impact of T1 slope has emerged as a predictor of kyphotic alignment change after laminoplasty. However, the relationship between T1 slope and postoperative cervical alignment change is not yet fully established. Purpose The goals of the present study were to investigate the relationship between T1 slope and loss of cervical lordosis (LCL), and to identify the role of T1 slope as a predictor of postoperative kyphosis after laminoplasty in patients with OPLL. Study Design This is a retrospective case study. Patient Sample Between January 2011 and January 2012, 64 consecutive patients who underwent cervical laminoplasty for OPLL were enrolled (male:female ratio=47:17; mean age=55.9 years). Cervical spine lateral radiographs in neutral, flexion, and extension were taken before surgery and at 2-year follow-up. Outcome Measures The C2–C7 Cobb angle, cervical range of motion (ROM), T1 slope, neck tilt, and C2–C7 sagittal vertical axis (SVA) were measured from lateral radiographs of the cervical spine preoperatively and postoperatively at 2-year follow-up. Methods Patients were divided into two groups according to preoperative T1 slope, and the postoperative cervical alignment change was compared between the groups. Postoperative kyphosis and LCL incidence were also evaluated at 2-year follow-up. The relationships between postoperative cervical alignment change and preoperative variables, including age, T1 slope, cervical ROM, C2–C7 SVA, and T1 slope minus C2–C7 Cobb angle (T1S−CL), were investigated. Results Patients were divided into two groups above and below median preoperative T1 slope (23.2°). There were no differences in age, sex, type of OPLL, or operation level between the two groups. Patients with higher preoperative T1 slope demonstrated significantly more lordotic preoperative cervical alignment (p=.001). Patients with higher preoperative T1 slope were more likely to exhibit postoperative LCL (p=.03), and when it occurred the degree of LCL was greater (p=.06). In multiple linear regression analysis, higher T1 slope (B=0.414, p=.04) and lower T1S−CL (B=−0.412, p=.03) were significantly associated with more postoperative LCL. In spite of these results, postoperative kyphosis did not occur more frequently in patients with higher T1 slope (p=.64). Conclusions Patients with higher T1 slope had more lordotic curvature before surgery and demonstrated more LCL at 2-year follow-up. Cervical alignment was compromised after laminoplasty, and the degree of LCL was correlated with preoperative T1 slope. After laminoplasty for cervical OPLL, patients with higher T1 slope tended to exhibit a greater LCL yet did not drift into frank postoperative kyphosis.
The average shear‐wave velocity within the top 30 m from the surface, VS30, represents site characteristics including the soil classification and site amplification that are essential information for ...building codes and seismic design. A novel method to determine a VS30 model based on a composite analysis of borehole standard penetration test numbers (SPT N) and horizontal‐to‐vertical (H/V) spectral ambient noise ratios is introduced. A national VS30 model for South Korea is determined using the method. The shear‐wave velocity structures beneath 20 nationwide broadband seismic stations are determined using the H/V analysis. The SPT N data are collected from 175,619 nationwide densely‐distributed boreholes. The shear‐wave velocity models from SPT N values are calibrated for the local reference velocity models from H/V analysis. A representative relationship between the SPT N values and shear‐wave velocities is introduced. A national VS30 model for South Korea is determined using the calibrated SPT N models at the nationwide boreholes. The VS30 model is verified by comparisons with local field measurements. The proposed model is consistent with the USGS model based on a surface slope analysis. The VS30 structure presents high correlation with geological and topographic features. The VS30 values are low in coastal (low topographic) areas, and high in mountain (high topographic) areas. Apparent linear relationship is observed between VS30 and topography. The western and southeastern coastal regions may be vulnerable to strong seismic shaking.
Plain Language Summary
Seismic ground motions are an important factor to control the seismic damages. The seismic amplification is highly dependent on the shear‐wave velocities at shallow depths ≤30 m, VS30. We introduce a novel method to determine a VS30 model based on the standard penetration test numbers (SPT N) from nationwide 175,619 boreholes and horizontal‐to‐vertical spectral ambient noise ratios (H/V ratios) from 20 broadband seismic stations. We determine a VS30 model for South Korea. The shear‐wave velocity structures beneath broadband seismic stations are used for local reference velocity models. The shear‐wave velocity models from SPT N values are calibrated for the local reference velocity models from the seismic stations. We determine a representative relationship between the SPT N values and shear‐wave velocities. We determine a high‐resolution VS30 model using the calibrated SPT N models at boreholes. The proposed model is verified by comparisons with other results. The VS30 structure presents high correlation with geological and topographic characteristics. The VS30 values are low in coastal areas, and high in mountain areas. The western and southeastern coastal regions may be vulnerable to strong ground motions during earthquakes.
Key Points
A novel method based on SPT N values and H/Vratios is proposed for determination of national VS30 model for South Korea
A high‐resolution national VS30 model can be calculated using the calibrated SPT N data at densely distributed boreholes
The VS30 model presents high correlation with geological and topographic features
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•Selective separation of quartz from apatite can be obtained using the collector at pH 3.•Adsorption of the collector on the mineral surface occures by electrostatic ...attraction.•Higher selective separation obtained due to higher adsorption of collector on quartz surface.•Hydrophobic interaction energy improved due to the collector adsorbed on the quartz surface.•Quartz particle can be reversely floated efficiently by high hydrophobicity interaction.
Dodecylamine hydrochloride (DAHC) surfactant was used as a collector for effective apatite recovery through flotation separation in siliceous phosphate ore, wherein quartz is the main gangue mineral. The roles of pH and collector concentration were investigated, and the adsorption of the collector on the minerals and related properties were systematically studied by measuring zeta potential, contact angle, surface tension, and adsorption density. When the collector concentration was 5×10−5M, 23.7% P2O5 grade was achieved for a conditioning time of 10min. However, the separation performance of the flotation was lower at pH 7 regardless of the collector concentration. Thus, more collector molecules are adsorbed on the quartz surface than the apatite surface at pH 3 and 5×10−5M of collector, resulting in separation of quartz and apatite. The extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, which considers the hydrophobic interaction energy, revealed that the improved flotation performance is attributed to a hydrophobic attractive force that is a consequence of the collector adsorption. Therefore, the results of flotation of artificially mixed minerals further revealed that optimization of the amine collector concentration and pH value can selectively separate quartz from apatite.
This paper presents an adaptive speed controller based on artificial intelligent technique to improvethe performance of classical Direct Torque Control (DTC) for Permanent Magnet Synchronous Motor ...(PMSM) drives. The proposed method applies back propagation (BP) based neural network (NN) to tune the parameters of classical proportional-integral (PI) speed controller. Comparisons between conventional PI speed controller and proposed method are carried out by Simulation.Simulation results demonstrate that conventional DTC system based on the proposed NN speed controller can achieve higher performance with fast speed response, small overshoot and robustness.
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