Study of pedicles and spinal canal diameters at the level of lumbar vertebral in normal adult Saudi population using computed tomography

The values of normal transverse (interpedicular) and sagittal (midsagittal) diameters are different at various levels of lumbar spinal canal in individuals of the same race and differ at identical levels in individuals of various races. The aim of the study was to determine normal reference range of the lumbar spinal canal dimensions and to evaluate lumbar pedicle dimensions with respect to spinal level, age, gender in Saudi population by using Computed Tomography. This study was conducted in Najran province (K.S.A), archival abdominal CT scan images from PACS in hospitals were used. The data of this study was collected from 210 (102 male and 108 female) normal Saudi adults individuals with different ages, gender over a period of 20 months (2019 - 2021). The mean spinal canal transverse distance (SCTR) showed steady decrease from L1 to L4, as there was an increasing in (SCTR) at L5 relative to L4, The mean spinal canal anteroposterior diameter (SCAP) showed a decrease from L1 to L3, and then a gradual increase from L4 to L5 (Fig.4-10). This pattern was observed in males only as there was an increase of female (SCAP) at L2 and L5, and no significant gender difference was noted at any lumbar level for (SCAP) The mean pedicle width (PW) showed steady increase from L1 to L5. While the mean pedicle height (PH) showed a gradual decrease from L1 to L5. The study conclude that Computed tomography is a reliable method for determining the morphological measurements of the spinal canal and pedicles diameter.

Study on combined machine for the subsurface soil treatment

The purpose of the study is to substantiate the relative position of the working bodies of a combined machine for non-fall tillage of winter crops. The design scheme and the principle of operation of the combined machine are given. The basic principles and methods of classical mechanics, mathematical analysis and statistics were used in this study. It is established that the most optimal design scheme of a combined machine for non-tillage of the soil and its preparation for sowing of repeated crops is considered to be a scheme consisting of non-tillage cases with crushers, a battery with cut-out spherical disks and a roller. According to the results of theoretical and experimental studies, it was found that with a longitudinal distance between the shaft-free bodies of 40 cm and a transverse distance of 90 cm, a longitudinal distance from the toe of the ploughshare to the center of the support wheel of 50 cm and a longitudinal distance from the toe of the ploughshare of the shaft-free body to the axis of rotation of the cut-out spherical disk of 120 cm, a longitudinal distance from the axis of rotation of the cut-out spherical disk to the center of the roller of 75 cm, high-quality tillage with minimal energy costs is provided.

Estimating Lane Change Duration for Overtaking in Nonlane-Based Driving Behavior by Local Linear Model Trees (LOLIMOT)

Lane change (LC) is one of the main maneuvers in traffic flow. Many studies have estimated LC duration directly by using lane-based data. The current research presents an estimate of LC duration for overtaking maneuver in nonlane-based traffic flow. In this paper, the LC duration is estimated implicitly by modeling lateral speed and applying the length of required lateral movement to complete the LC maneuver. In lateral speed modeling, the local linear model tree is applied which consists of three variables: the initial lateral distance, longitudinal speed, and time to collision (TTC), which itself is a function of the relative speed of follower and the distance between the two vehicles. The initial lateral distance is the relative transverse distance from which the following vehicle initializes the LC. The range of lateral speed was estimated between 0.5 and 5 km/h, which resulted in the LC duration between 2.5 and 24 sec. The results indicate that the lateral and longitudinal speed would be inversely related, while the lateral speed and the initial transverse distance as well as TTC would be directly related. The findings also indicate that TTC can be assumed as the most important factor affecting lateral speed. TTC at 8 sec can be considered as the threshold for its effect on the LC duration since at longer TTCs, and the lateral speed has remained almost constant. When TTC is longer than 8 sec, it would not affect the LC duration.

Behaviour Analysis of Left-Turning Mopeds at Signal Controlled Intersections – A Case Study in Yancheng City

Mopeds (electric bicycles and light motorcycles) are commonly used as a personal transportation mode in China. However, the understanding of characteristics of left-turning mopeds at signal-controlled intersections has been relatively limited. To bridge this gap, firstly, this paper proposed a video conversion method of moped movement data acquisition. Then, a method of data accuracy verification was introduced by comparing the results between the field experiment and the video conversion method. Secondly, the ideal traffic space for left-turn mopeds from different entrances was defined to analyse the characteristics of the left-turning mopeds at intersections. Further, three indicators, namely, transverse distance, the proportion of left-turning mopeds with crossing behaviour, and the average number of avoidance behaviour, were proposed and used to analyse the asymmetrical characteristics behaviour, crossing behaviour, and avoidance behaviour. Finally, based on empirical data collected from five signal-controlled intersections, the proposed methods and behaviours were analysed. This paper provides both a valid method of obtaining the position data of mopeds and a reliable basis for improving the safety of left-turning moped riders at urban signal-controlled intersections.

Experimental Measurements and Numerical Investigations on the Aerodynamic Performance and Internal Flow Fields of Tangential Admission Volutes for Steam Turbines

Steam turbines are applied in production plants characterized by very large injections of steam. For this reason, the design and optimization of the admission are fundamentals to obtain an adequate level of turbine efficiency and ensure uniform flow at the inlet of the low pressure stages downstream the injection. In conjunction with a flexible operation and partial load conditions, it is important to estimate the losses appearing at those admissions sufficiently. The aerodynamic performance and flow field of the individual tangential admission volute and tangential admission volute coupled with the downstream vanes were experimentally measured and numerically simulated in this paper. The total pressure loss, outlet flow angle and mass flow rate of the individual tangential admission volute at three different outlet Mach numbers and tangential admission volute coupled with the downstream vanes at four different inlet total pressures were measured. The flow field of the experimental tangential admission volute for the steam turbine was numerically investigated using threedimensional Reynolds-Averaged Navier-Stokes (RANS) and SST turbulence model. The numerical aerodynamic parameters of the tangential admission volute were in good agreement with the experimental data. The accuracy of the presented numerical method was validated. The flow field and aerodynamic parameters of tangential admission volute coupled with the downstream vanes were discussed under different inlet total pressure flow conditions. Then, three volute cases with different transverse distance were designed to investigate the influence of different outlet airflow angles on the aerodynamic performance of the downstream vanes. Results show that the outlet airflow angle of the individual tangential admission volute and tangential admission volute coupled with the downstream vanes usually keep constants when the inlet total pressure is increases. The averaged outlet airflow angle of the individual tangential admission volute and tangential admission volute coupled with the downstream vanes equal 152.0° and 166.6°, respectively. Comparing with the individual tangential admission volute, the outlet airflow angle of the tangential admission volute coupled with the downstream vanes is more uniform. The total pressure loss and mass flow rate of the individual tangential admission volute and tangential admission volute coupled with the downstream vanes increase with the inlet total pressure. With the increase of the inlet total pressure, the total pressure loss coefficient of the individual tangential admission volute increases from 0.73% to 1.64%. In the same case, the total pressure loss of the tangential admission volute coupled with the downstream stator vane increases from 0.82% to 2.66%. The average airflow angle of the volute increases with the increase of the transverse distance. With the increase of the transverse distance, the total pressure loss coefficient of the volute increases and the total pressure loss coefficient of the vanes decreases. At the same time, the total pressure loss coefficient of the whole model decreases at first and then increases. The present work provides the reference for the design and performance analysis of the tangential admission volute for the steam turbines.

Effects of Fin Arrangements on Thermal Hydraulic Performance of Supercritical Nitrogen in Printed Circuit Heat Exchanger

The printed circuit heat exchanger (PCHE) with discontinuous fins is a novel type of compact and highly efficient plate heat exchanger, which has superior thermal hydraulic performance. The morphology and characteristics of the flow channel greatly affect the performance of the PCHE. The discontinuous airfoil fins are used in PCHE channel design because they can affect the flow and heat transfer by increasing the heat transfer area and the disturbance in the channel. In this paper, the effects of different staggered distance (Ls) and transverse distance (Lv) of airfoil fin arrangements on the heat transfer and flow of supercritical nitrogen in the PCHE are numerically simulated using ANSYS Fluent. Simulation results and subsequent analysis show that the appropriate decrease in Ls and reduction in Lv between the two rows of fins can improve the convective heat transfer of the PCHE. A fully staggered arrangement of fins (Ls = 1.2) and an appropriate increase in the Lv can mitigate pressure drop. The comprehensive performance of different channel geometries is compared by the performance evaluation criteria (PEC) in this study. It is shown that considering flow resistance and heat transfer, the comprehensive heat transfer performance can be enhanced by properly increasing the staggered distance and the vertical distance between fins. When Ls = 1.2 mm and Lv = 1.25 mm, the PEC value of the staggered channel is the highest, which is 11.6% higher than that of the parallel channel on average.

A DESCRIPTIVE STUDY OF MORPHOMETRIC DATA OF FEMORAL CONDYLES BY DIRECT METHOD TO DETERMINE DIFFERENCE ON RIGHT & LEFT SIDE IN RAJASTHAN REGION

Background: There are no published studies on the anthropometry of the distal femur in the Indian population. Hence the results obtained from this study would provide valuable data on the average dimensions of the distal femur which can serve as guidelines for designing a suitable femoral component of total knee prostheses for this population. Methods: After applying inclusion and exclusion criteria 41 dried femur of each side (total 82) of unknown age and sex will be selected for present study. The maximum anteroposterior distance & maximum transverse distance of lateral femoral condyle, maximum anteroposterior distance & maximum transverse distance of medial femoral condyle width was measured. Results: In the present study the mean AP diameter of the medial condyle on right side was 54.55±6.88 mm and on left side was 54.36±3.56 mm, The mean Transverse diameter of the medial condyle was 27.33±3.09 mm and 25.03±1.99 mm on right and left side respectively. In AP diameter parameters no statistically significant difference found between right and left side because p value was >.05 for both parameters. But in Transverse diameter parameters are statistically significant found between right and left side because p value was <.05. Conclusion: On comparison between right and left side measurements, no significant difference was found between values of parameters of right and left sided femur. This information will be useful to negate the need of side specific measurements for implant Keywords: Femur, left, Right

Combination machine for soil cultivation and sowing grain

The purpose of the study is to substantiate the design scheme and parameters of the working bodies of a combined machine for tillage and sowing grain on sloping lands. The authors have developed a machine that performs technological operations for tillage, grain sowing, and ridge formation to prevent water erosion. The design diagram is given. The basic principles and methods of classical mechanics, mathematical analysis, and statistics were used in this study. Theoretical and experimental studies have established that using a chisel-shaped ripper with loosening knives as a loosening working body provides high-quality loosening of the soil. When the longitudinal and transverse distances between the rippers are 62.5 and 15 cm, respectively, the longitudinal distance between the rear ripper and the housing is 60 cm, and the transverse distance between the buildings is 90 cm, high-quality soil loosening, and grain sowing are achieved with minimal energy consumption.

Two-dimensional flow field distribution characteristics of flocking drainage pipes in tunnel

With the rapid development of traffic infrastructure in China, the problem of crystal plugging of tunnel drainage pipes becomes increasingly salient. In order to build a mechanism that is resilient to the crystal plugging of flocking drainage pipes, the present study used the numerical simulation to analyze the two-dimensional flow field distribution characteristics of flocking drainage pipes under different flocking spacings. Then, the results were compared with the laboratory test results. According to the results, the maximum velocity distribution in the flow field of flocking drainage pipes is closely related to the transverse distance h of the fluff, while the longitudinal distance h of the fluff causes little effect; when the transverse distance h of the fluff is less than 6.25D (D refers to the diameter of the fluff), the velocity between the adjacent transverse fluffs will be increased by more than 10%. Moreover, the velocity of the upstream and downstream fluffs will be decreased by 90% compared with that of the inlet; the crystal distribution can be more obvious in the place with larger velocity while it is less at the lower flow rate. The results can provide theoretical support for building a mechanism to deal with and remove the crystallization of flocking drainage pipes.