Association of Iris Structural Measurements with Corneal Biomechanics in Myopic Eyes

Purpose. To evaluate the relationship between iris sectional parameters on swept-source optical coherence tomography (SS-OCT) with corneal biomechanics measured by Corneal Visualization Scheimpflug Technology (Corvis ST) in young adults with myopia. Methods. 117 patients with myopia aged ≥18 years were recruited from the Eye Hospital of Wenzhou Medical University, who had complete SS-OCT and Corvis ST data. Only the left eye of each participant was selected for analysis. Iris sectional parameters included iris thickness at 750 μm from the scleral spur (IT750), iris sectional area (I-area), and iris curvature (I-curv) measured from four quadrants. Associations between the iris parameters and corneal biomechanics were analyzed using linear regression models. Results. The mean age of the included young adults was 26.26 ± 6.62 years old with 44 males and 73 females. The iris parameters were different among the four quadrants. The nasal, temporal, and inferior quadrants of IT750, together with nasal and temporal quadrants of I-area, were correlated with corneal biomechanical parameters after being adjusted for age, gender, pupil diameter, and axial length. Thicker IT750 and larger I-area were related to a softer cornea. However, no association was found between I-curv and corneal biomechanics. Conclusions. Iris sectional parameters measured from SS-OCT images were associated with corneal biomechanical properties in myopic eyes. Thicker IT750 and larger I-area indicate a softer cornea. IT750 and I-area may provide useful information on corneal biomechanical properties in myopic eyes.

DETERMINATION OF THE OPTIMAL CURVATURE OF ELASTIC DEFORMED CABLES IN THE MIDDLE OF THE SPAN IN A HANGING COATING BY USING THE MATHCAD COMPUTER SYSTEM

The paper presents the theoretical results of improving and refining the general methodology for selecting the cross section of a flexible elastic thread for cable-stayed using the capabilities of computer programs. A technique is proposed for finding the optimal curvature of the cable in the middle of the span by compiling the target function of the cable cost and coverage and determining its minimum. The hanging coating of the building is considered, consisting of parallel-located flexible cables. Coating elements are laid on them. It is assumed that the load is evenly distributed over the curved surface of the coating. With this application of load, the sag curve is adopted as a chain line. In the calculation, two states of the thread are considered. In the first state, it is loaded with a linear load uniformly distributed along its length from its own weight. In the second state, the thread is loaded with the total calculated linear load evenly distributed along its length. To select the cross section of the thread, the maximum longitudinal force arising in it in the second state is determined, which depends on the curvature in the middle of the span. This curvature is determined on the basis that the difference between the lengths of the thread in the first and second states is equal to the elastic elongation according to Hooke's law. Using ordinary algebraic methods, solving the problem is quite complicated. Therefore, it was proposed to solve it using the MathCAD computer system. With the found value of the curvature in the middle of the span, the required cross-sectional area of the thread is calculated. After that, the appropriate rope is selected according to the assortment. To optimize the cable-stayed coating, the optimal curvature in the middle of the span is determined in the first state, at which the total cost of cable-stayed and coating will be minimal. For this purpose, the objective function of the cost of the cable and the coverage that lies on this cable has been compiled. To determine the optimal curvature, it is proposed to accept a series of values of this curvature with some step in a certain range. For each curvature, the value of the objective function is calculated. Using the MathCAD computer system, it is proposed to build the graph of the objective function and find the value of the optimal curvature at which this function has a minimum. After that, it is proposed to find the corresponding optimal sagging arrow. The proposed method allows us to determine the optimal parameters of the hanging coating with parallel cables on the basis of the minimum cost, as well as to calculate the necessary cross-sectional parameters of the flexible cable from the strength condition.

Finite element model of laminate construction element with multi-phase microstructure

The article describes a method of creating a mesoscale finite element model of a fabric reinforced laminate that replicates the smallest repetitive fragment of its microstructure – RUC (Repetitive Unit Cell). The model takes into account the influence of the number and orientation of layers, the weave of the reinforcement fabric as well as manufacturing technology on the strength and stiffness of the laminate. The constants of the finite elements forming RUC (equivalent cross-sectional parameters, limit values of forces ensuring layer integrity) are determined experimentally by performing uncomplicated tests of specimens of a particular laminate. A special preprocessor was developed to generate the finite element model of the construction element from laminate, which automatically creates the so-called batch file defining the model. The usefulness of the preprocessor was checked by simulating a three-point bending test of a laminate door beam of a passenger car. The obtained calculation results were verified experimentally.

Study regarding the Establishment of Cross-sectional Parameters of Forming Taps

In the paper is presented some consideration regarding the parameters that influence the cross sectionalparameters of forming tap. It is taking into account the parameters that have a great influence on the ridges of theforming taps which determine the contour shape of the forming tap’s ridges, the radius of the ridge profile, anddetermination of the radial chamfer relief of the forming tap.Also are shown the influence of the correlation angle on ridge thread that determine the contact area between thetop of the working ridge and of the part subjected to plastic deformation in order to avoid its cutting.

Modeling and Experimentation of the Unidirectional Orthodontic Force of Second Sequential Loop Orthodontic Archwire

The abnormal tooth arrangement is one of the most common clinical features of malocclusion which is mainly caused by the tooth root compression malformation. The second sequential loop is mostly used for the adjusting of the abnormal tooth arrangement. Now, the shape devise of orthodontic archwire depends completely on the doctor’s experience and patients’ feedback, this practice is time-consuming, and the treatment effect is unstable. The orthodontic-force of the different parameters of the second sequence loop, including different cross-sectional parameters, material parameters, and characteristic parameters, was compared and simulated for the abnormal condition of root compression deformity. In this paper, the analysis and experimental study on the unidirectional orthodontic-force were carried out. The different parameters of the second sequential loop are analyzed, and the equivalent beam deflection theory is used to analyze the relationship between orthodontic-force and archwire parameters. Based on the structural analysis of the second sequential loop, the device for measuring orthodontic force has been designed. The orthodontic force with different structural characteristics of archwire was compared and was measured. Finally, the correction factor was developed in the unidirectional orthodontic-force forecasting model to eliminate the influence of inherent error. The average relative error rate of the theoretical results of the unidirectional orthodontic-force forecasting model is between 12.6% and 8.75%, which verifies the accuracy of the prediction model.

Characterization of drag reduction performance over rotating microgrooves with different cross-sections

This paper presents a study of cross-sectional parameters and optimal drag reduction performance specifically for drag reduction in rotating microgroove applications. Rotating triangular microgrooves with nine asymmetrical and symmetrical cross-sections were numerically studied. In addition, a representative symmetrical rotating microgroove was experimentally tested. Positive asymmetrical microgrooves (including symmetrical microgrooves) were found to be sensitive to rotating Reynolds numbers and produced more significant drag reduction. Compared with a dimensioned asymmetry variable and other dimensionless parameters, the dimensionless asymmetry variable i+ could be used to describe drag reduction performance, which captured both the influence of microgroove cross-sectional asymmetry and turbulence intensity. A maximum drag reduction of up to 8.9% was obtained at 9.2 i+. With the exception of the torque, the velocity shift obtained from dimensionless velocity profiles could also be used to predict drag reduction performance, which has the potential for wider and more comprehensive application for any drag reduction technology.

Solid rocket motor design using a surrogate model

Purpose This study aims to determine the relationship between sectional geometric parameters of a slotted solid rocket propellant on structural integrity and internal ballistic performance of a rocket motor by using response surface method. Design/methodology/approach Zero-dimensional (0D) ballistic solver is developed and validated to determine the effects of sectional geometric parameters on internal ballistic performance of a rocket motor. Additionally, effects of these parameters on structural strength of the system are examined by performing linear viscoelastic finite element analysis under plane strain assumption. Results of the 0D internal ballistic analyses are used as an input to the structural analysis. Findings Different response surfaces are constructed to represent the characteristic variation of solid propellant’s structural strength and internal ballistic performance with respect to design variables. Originality/value Coupled analysis methodology in terms of structural strength and internal ballistic performance presented in this work facilitates many designers who are working on solid rocket motor development. This study represents graphical results summarizing effects of sectional parameters of a slotted grain on both internal ballistic performance and structural strength results. Additionally, graphical results summarizing the effects of sectional parameters on structural strength and internal ballistic performance provide useful information for researchers that lessens design period. Finally, validations presented in this work can also be used as a benchmark reference for different studies.

Wavelet and index methods for the identification of pool–riffle sequences

The accuracy of hydraulic models depends on the quality of the bathymetric data they are based on, whatever the scale at which they are applied (e.g., 2D or 3D reach-scale modeling for local flood studies or 1D modeling for network-scale flood routing). The along-stream (longitudinal) and cross-sectional geometry of natural rivers is known to vary at the scale of the hydrographic network (e.g., generally decreasing slope, increasing width, etc.), allowing parameterizations of main cross-sectional parameters with proxy such as drainage area or a reference discharge quantile (an approach coined downstream hydraulic geometry, DHG). However, higher-frequency morphological variability is known to occur for many stream types, associated with varying flow conditions along a given reach: alternate bars, pool-riffle sequences, meanders, etc. To better take this high-frequency variability in bedforms into account in hydraulic models, a first step is to design robust methods to characterize the scales at which it occurs. In this paper, we propose and benchmark several methods to identify bedform sequences in pool-riffle morphology, for six small French rivers: the first one called the index method, based on three morphological and hydraulic descriptors; the second one called wavelet ridge extraction, performed on the continuous wavelet transform (CWT) of bed elevation. Finally, these new methods are compared with the bedform differencing technique (BDT, O’Neill and Abrahams (1984)), compared by computing a score that gives a percentage of agreement along the total surveyed length and by calculating the number of bedforms and the pool spacings for each method. The three methods were found to give similar results on average for wavelength estimation, with agreement from 64% to 84% and a similar number of bedforms identified. The filter-like behavior of the wavelet ridge analysis tends to give more robust results for the estimation of mean bedform amplitude, which varies from 0.30 to 0.81 with an SNR (signal-to-noise ratio) from 2.68 to 7.91. Otherwise, BDT gives higher mean bedform amplitude but lower SNR values from 0.85 to 1.73.

The concept of modification and analysis of the strength of steel roadway supports for coal mines in the Soma Basin in Turkey

The article presents a comparison of the roadway supports currently used in mines in the Soma basin in Turkey with new one proposed by Huta Łabędy and Central Mining Institute (GIG) in terms of resistance parameters and work in conditions of specific loads. The strength analysis of the frame was carried out using the finite element method, using the COSMOS/M program, based on the methodology developed and applied in GIG. The frame models were built corresponding to their geometry and cross-sectional parameters of the sections used. Beam elements (BEAM3D) were used for building models, which were given cross-sectional parameters of the V36 section. This resulted in three frame models that were loaded in three ways (three load variants). The first option included roof load, acting on the roof bar in a uniform manner, at a length of about 3.0 m. In the second variant, the same load was adopted but the resistance of the side wall was omitted. However, in the third variant, the same roof load was assumed in addition to a side load, acting on the sliding arch, at a length of about 3.0 m, a value corresponding to half the load of the roof. As a result of the calculations carried out, the distribution of reduced stresses in the analysed frames and the maximum load values were obtained. The proposed roadway supports retain the functionality of the previously used frames in terms of width, height, cross-sectional area of the support and the number of elements. They are characterised by the same weight and at the same time, they have up to 24% more load capacity because of the replacement of straight sections of curved side sections. This treatment was possible by forming individual elements of the arch with two bending radii. The additional load increase was obtained by using S550W steel.