Age Estimation Based on Computed Tomography Analysis of the Scapula.

Background and Objectives: Age estimation from skeletal remains and in living individuals is an important issue for human identification, and also plays a critical role in judicial proceedings for migrants. Forensic analysis of ossification centers is the main evaluation method for age estimation, and ossification degree can be determined using computed tomography analysis. The purpose of this study is to investigate the applicability of CT (computed tomography) in the analysis of left scapula ossification centers, for forensic age estimation in Turkish society. Materials and Methods: We analyzed six ossification centers of the left scapula and these ossification centers are the coracoid, subcoracoid, coracoid apex, acromial, glenoid, and inferior angle ossification centers. A pediatric radiologist analyzed these six ossification centers of the scapula by using a staging method defined by Schmeling et al. in 2004. Two months after the first assessment, 20 randomly selected cases was reanalyzed by the first observer and by another pediatric radiologist. Correlation between the age and ossification stage was assessed using Spearman's nonparametric correlation test. Linear regression analysis was performed using a backwards model. Cohen's kappa coefficient was used for evaluating interobserver and intraobserver variability. Results: In this retrospective study, 397 (248 male and 149 female) cases were evaluated. Ages ranged between 7.1 and 30.9. The mean age was 19.83 ± 6.49. We determined a positive significant correlation between the age and the ossification stages of ossification centers analyzed in both sexes. In each ossification center, except inferior angle, all of the stage 1 and 2 cases in both sexes were under 18 years old. Intraobserver and interobserver evaluations showed that reproducibility and consistency of the method was relatively good. Conclusions: The present study indicated that CT analysis of scapula ossification centers might be helpful in forensic age assessment of living individuals and dry bones

Cost-efficient approximation of linear systems with repeated and multi-channel filtering configurations

It is possible to obtain either exact realizations or useful approximations of linear systems or matrix-vector products arising in many different applications, by synthesizing them in the form of repeated or multi-channel filtering operations in fractional Fourier domains, resulting in much more efficient implementations with acceptable decreases in accuracy. By varying the number and configuration of filter blocks, which may take the form of arbitrary flow graphs, it is possible to trade off between accuracy and efficiency in the desired manner. The proposed scheme constitutes a systematic way of exploiting the information inherent in the regularity or structure of a given linear system or matrix, even when that structure is not readily apparent

Performance prediction of a jumbo drill in ankara-pozanti motorway tunnel (Turkey)

In this study, the performance prediction of a jumbo drill used in Pozanti-Ankara Motorway Tunnel (Kirkgecit-1) was investigated. The performance of the drill was observed in once every 50 meters of the tunnel route. Rock blocks were collected from each observation points for the laboratory tests. In addition, joint count was performed on the tunnel face in each observation point. Schmidt hammer, P-wave velocity, impact strength and density values of the rock samples were determined in the laboratory. For each observation point, volumetric joint count (JV), which is defined as the sum of the number of joints per meter for each joint set, was calculated from joint measurements. Penetration rates of the drill were firstly correlated with rock properties. It was found that there was no correlation between the penetration rate and intact rock properties. This is due to the fact that rock properties belonging to each observation point are approximately same. Then, penetration rates were correlated with Jv values and found strong correlation. Penetration rate linearly decreases with increasing Jv values. Concluding remark is that, if the intact rock properties are approximately same, drilling performance of jumbo drill depends largely on the discontinuities on the rock mass

A comparison and identification study of dry sliding wear behaviour of Al/B4CP and Mg/B4CP composites for automobile disk brakes

SAE 2014 World Congress and Exhibition -- 8 April 2014 through 10 April 2014 -- Detroit, MI -- 104424The brake friction materials in an automotive brake system play an important role in the overall braking performance of a vehicle. Metal Matrix Composites (MMCs) have been widely investigated and applied due to their advantages of improved strength, stiffness and increased wear resistance over the monolithic alloys in automobile industries. In this paper, Al/B 4CP and Mg/B4CP composites were compared to find a suitable candidate material for automotive disk brake application, in terms of wear behavior results of the materials. In addition, the experimental data was also used to model this behavior by identification. The measured tangential force was considered as the input parameter, whereas the weight loss as the output parameter. Preliminary results of this work showed that B4CP addition improved wear resistance of both aluminum and magnesium matrix composites. Additionally, the study pointed out that identified models provide a reliable and cost effective tool for wear prediction. Copyright © 2014 SAE International

Space-bandwidth-efficient realizations of linear systems

One can obtain either exact realizations or useful approximations of linear systems or matrix-vector products that arise in many different applications by implementing them in the form of multistage or multichannel fractional Fourier-domain filters, resulting in space-bandwidth-efficient systems with acceptable decreases in accuracy. Varying the number and the configuration of filters enables one to trade off between accuracy and efficiency in a flexible manner. The proposed scheme constitutes a systematic way of exploiting the regularity or structure of a given linear system or matrix, even when that structure is not readily apparent. (C) 1998 Optical Society of America