Comparative study on multibody vehicle dynamics models based on subsystem synthesis method using Cartesian and joint coordinates

AbstractThe subsystem synthesis method has been developed in order to improve computational efficiency for a multibody vehicle dynamics model. Using the subsystem synthesis method, equations of motion of the base body and each subsystem can be solved separately. In the subsystem synthesis method, various coordinate systems can be used and various integration methods can be applied in each subsystem, as long as the effective mass matrix and the effective force vector are properly produced. In this paper, comparative study has been carried out for the subsystem synthesis method with Cartesian coordinates and with joint relative coordinates. Two different integration methods such as an explicit integrator and an explicit implicit integrator are employed. In order to see the accuracy and computational efficiency from the different models based on the different coordinate systems and different integration methods, a rough terrain run simulations has been carried out with a 6 × 6 off-road multibody vehicle model

Engineering new bone tissue in vitro on highly porous poly(Α-hydroxyl acids)/hydroxyapatite composite scaffolds

Engineering new bone tissue with cells and a synthetic extracellular matrix (scaffolding) represents a new approach for the regeneration of mineralized tissues compared with the transplantation of bone (autografts or allografts). In the present work, highly porous poly( L -lactic acid) (PLLA) and PLLA/hydroxyapatite (HAP) composite scaffolds were prepared with a thermally induced phase separation technique. The scaffolds were seeded with osteoblastic cells and cultured in vitro . In the pure PLLA scaffolds, the osteoblasts attached primarily on the outer surface of the polymer. In contrast, the osteoblasts penetrated deep into the PLLA/HAP scaffolds and were uniformly distributed. The osteoblast survival percentage in the PLLA/HAP scaffolds was superior to that in the PLLA scaffolds. The osteoblasts proliferated in both types of the scaffolds, but the cell number was always higher in the PLLA/HAP composite scaffolds during 6 weeks of in vitro cultivation. Bone-specific markers (mRNAs encoding bone sialoprotein and osteocalcin) were expressed more abundantly in the PLLA/HAP composite scaffolds than in the PLLA scaffolds. The new tissue increased continuously in the PLLA/HAP composite scaffolds, whereas new tissue formed only near the surface of pure PLLA scaffolds. These results demonstrate that HAP imparts osteoconductivity and the highly porous PLLA/HAP composite scaffolds are superior to pure PLLA scaffolds for bone tissue engineering. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res 54: 284–293, 2001Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34419/1/16_ftp.pd

The secondary prophylactic efficacy of beta-blocker after endoscopic gastric variceal obturation for first acute episode of gastric variceal bleeding

Background/AimsThe most appropriate treatment for acute gastric variceal bleeding (GVB) is currently endoscopic gastric variceal obturation (GVO) using Histoacryl®. However, the secondary prophylactic efficacy of beta-blocker (BB) after GVO for the first acute episode of GVB has not yet been established. The secondary prophylactic efficacy of BB after GVO for the first acute episode of GVB was evaluated in this study.MethodsNinety-three patients at Soonchunhyang University Hospital with acute GVB who received GVO using Histoacryl® were enrolled between June 2001 and March 2010. Among these, 42 patients underwent GVO alone (GVO group) and 51 patients underwent GVO with adjuvant BB therapy (GVO+BB group). This study was intended for patients in whom a desired heart rate was reached. The rates of rebleeding-free survival and overall survival were calculated for the two study groups using Kaplan-Meyer analysis and Cox's proportional-hazards model.ResultsThe follow-up period after the initial eradication of gastric varices was 18.14±25.22 months (mean±SD). During the follow-up period, rebleeding occurred in 10 (23.8%) and 21 (41.2%) GVO and GVO+BB patients, respectively, and 39 patients died [23 (54.8%) in the GVO group and 16 (31.4%) in the GVO+BB group]. The mean rebleeding-free survival time did not differ significantly between the GVO and GVO+BB groups (65.40 and 37.40 months, respectively; P=0.774), whereas the mean overall survival time did differ (52.54 and 72.65 months, respectively; P=0.036).Conclusions Adjuvant BB therapy after GVO using Histoacryl® for the first acute episode of GVB could decrease the mortality rate relative to GVO alone. However, adjuvant BB therapy afforded no benefit for the secondary prevention of rebleeding in GV

Position Prediction in Space System for Vehicles Using Artificial Intelligence

This paper deals with the prediction of the future location of vehicles, which is attracting attention in the era of the fourth industrial revolution and is required in various fields, such as autonomous vehicles and smart city traffic management systems. Currently, vehicle traffic prediction models and accident prediction models are being tested in various places, and considerable progress is being made. However, there are always errors in positioning when using wireless sensors due to various variables, such as the appearance of various substances (water, metal) that occur in the space where radio waves exist. There have been various attempts to reduce the positioning error in such an Internet of Things environment, but there is no definitive method with confirmed performance. Of course, location prediction is also not accurate. In particular, since a vehicle moves rapidly in space, it is increasingly affected by changes in the environment. Firstly, it was necessary to develop a spatial positioning algorithm that can improve the positioning accuracy. Secondly, for the data generated by the positioning algorithm, a machine learning method suitable for position prediction was developed. Based on the above two developed algorithms, through experiments, we found a means to reduce the error of positioning through radio waves and to increase the accuracy of positioning. We started with the idea of changing the positioning space itself from a three-dimensional space into a two-dimensional one. With changes in the time and space of radio wave measurement, the location was measured by transforming the spatial dimension to cope with environmental changes. This is a technology that predicts a location through machine learning on time series data using a direction angle classification technique. An experiment was conducted to verify the performance of the proposed technology. As a result, the accuracy of positioning was improved, and the accuracy of location prediction increased in proportion to the learning time. It was possible to confirm the prediction accuracy increase of up to 80% with changes. Considering that the accuracy result for location prediction presented by other researchers is 70%, through this study, the result was improved by 10% compared to the existing vehicle location prediction accuracy. In conclusion, this paper presents a positioning algorithm and machine learning methodology for vehicle positioning. By proving its usefulness through experiments, this study provides other researchers with a new definition of space for predicting the location of a vehicle, and a machine learning method using direction angles

Data from: Combination of shear-wave elastography and color Doppler: feasible method to avoid unnecessary breast excision of fibroepithelial lesions diagnosed by core needle biopsy

Background: We evaluated shear-wave elastography (SWE) and color Doppler ultrasonography (US) features for fibroepithelial lesions (FELs), and to evaluate their utility to differentiate fibroadenomas (FAs) and phyllodes tumors (PTs). Methods: This retrospective study included 67 FELs pathologically confirmed (49 FAs, 18 PTs). B-mode US, SWE and color Doppler US were performed for each lesion. Mean elasticity (Emean), maximum elasticity (Emax), and vascularity were determined by SWE and Doppler US. Diagnostic performances were calculated to differentiate FAs and PTs. Equivocal FELs diagnosed by core needle biopsy (CNB) were further analyzed. Results: Median Emean and Emax were significantly lower for FAs than PTs (Emean, 15.7 vs. 66.7 kPa; Emax, 21.0 vs. 76.7 kPa, P43.9 kPa, 89.8%; Emax >46.1 kPa, 79.6%) than B-mode US (42.9%) (P0.05). The combination of SWE and Doppler US with ‘Emean>43.9 kPa or high vascularity (≥2 vessel flows)’ showed a higher area under the curve (0.786 vs. 0.687) and higher diagnostic values than B-mode US (sensitivity, 100 vs. 94.4 %; specificity, 57.1 vs. 42.9 %; positive predictive value, 46.2 vs. 37.8 %; negative predictive value, 100 vs. 95.5 %), without statistical significance (P>0.05). Of the 30 equivocal FELs, all lesions with ‘Emean≤43.9 kPa and low vascularity (0-1 vessel flow)’ (23.3%, 7/30) were finally confirmed as FAs by excision. Conclusion: FAs have a tendency to have less stiffness and lower vascularity than PTs. Combined SWE and color Doppler US may help patients with equivocal FELs diagnosed by CNB avoid unnecessary excision