Location Of Reference Point Research Articles

Concordance and reproducibility in the location of reference points for a volumetric craniofacial analysis: Cross-sectional study.

Considering the limitations of visualization that occur even with the use of radiographs, the cone beam computed tomography (CBCT) becomes more attractive to diagnose and propose an assertive treatment plan. This study aimed to evaluate intra and interobserver reproducibility, and concordance of 31 reference points we described considering visualization tools and the three planes of space in a bimaxillary CBCT. Three observers located in triplicate the 31 reference points in the CBCT of six healthy patients. Friedman test was used to compare intraobserver paired samples, and interobserver concordance was determined by the intraclass correlation coefficient (ICC) with ranges>0.75 (excellent), between 0.60 and 0.74 (good), between 0.40 and 0.59 (sufficient) and<0.40 (poor). The P value was set at<0.05. A high ICC (>0.75%) was obtained by comparing the x, y, and z values at the location of landmark points. Excellent ICC>0.75 was for 81.7% and poor<0.40 was 7.5% in the interobserver evaluation. Data showed that 25 points had excellent concordance on the x-plane, 25 on the y-plane, and 26 on the z-plane (0.75%). Intraobserver concordance analysis indicated that location of anatomical reference points on bimaxillary CBCT is performed with great reproducibility by interpreting their location with a clear description in the three planes of space. Complexity of achieving a good precision degree in the manual marking of reference points caused by convexities of the anatomical structures involved, might explain the variability found. The systematized location of the reference points would contribute to reduce such variability.

Computer-Aided Assessment of Three-Dimensional Standard Bone Morphology of the Distal Radius.

The present study attempted to define the three-dimensional (3D) locations of reference points and standard measures of the distal radius of a normal wrist joint. One hundred wrists from 50 males and 50 females who matched the age distribution (19-95 years old, mean: 56.0 years old) were evaluated. Computed tomography (CT) images of normal wrist joints acquired for comparison with the affected side were used. The absence of a previous history and complaints in the unaffected wrist was confirmed in an interview and with medical records. Three-dimensional images of the distal radius were reconstructed using the data obtained from CT scans. The site at which the major axis of the radial diaphysis contacted the distal radius joint surface was defined as the origin. The 3D coordinates of reference points for the radial styloid process (1), sigmoid notch volar edge (2), and sigmoid notch dorsal edge (3) as well as the barycenter for the joint surface and joint surface area were evaluated. A slope of the line connecting coordinates 1-2 in the coronal plane was evaluated as the 3D radial inclination (3DRI) and that connecting coordinates 2-3 in the sagittal plane as the 3D palmar tilt (3DPT). Each measurement value was compared between males and females. The positions of each reference point from the origin were as follows: (1) 14.2 ± 1.3/12.6 ± 1.1 mm for the distal-palmar-radial position; (2) 19.3 ± 1.3/16.9 ± 1.3 mm for the proximal-palmar-ulnar position; (3) 15.6 ± 1.4/14.1 ± 0.9 mm for the proximal-dorsal-ulnar position; and (barycenter) 4.1 ± 0.7/3.7 ± 0.7 mm for the proximal-volar-ulnar position for males and females, respectively. The areas of the radius articular surface were 429.0 ± 67.9/347.6 ± 44.6 mm2 for males and females, respectively. The 3DRI and 3DPT were 24.2 ± 4.0/25.7 ± 3.1° and 10.9 ± 5.1/13.2 ± 4.4° for males and females, respectively. Significant differences were observed in all measurement values between males and females (p &lt; 0.01). The reference points and measured values obtained in the present study will serve as criteria for identifying the dislocation direction and reduction conditions of distal radius fractures in 3D images.

Evaluating the relation of posterior occlusal plane to ala-tragal line according to age and sex.

Occlusal plane orientation affects the esthetic, function, and success of removable or fixed prostheses. The most prevalent index for determination of this plane is the ala-tragus line while there are controversies in the exact location of tragus reference point.

A Review of Factors Influencing Rolling Shear in CLT and Test Methodology

Abstract Rolling shear (RS) is one of the key design parameters that influence the out-of-plane bending stiffness of cross-laminated timber (CLT) panels and thus affects the design and performance of CLT floor and wall systems. Various experimental methods are currently used to determine the RS capacity of CLT panels and feedstock. Some methods have been adapted to measure RS properties of clear wood such as Iosipescu, Arcan, and single cube apparatus, but there is no specific standard test method to accurately determine the RS stiffness or strength of CLT feedstock. This article presents a comprehensive review of potential RS test methods and highlights the importance of considering RS in CLT design. Test methods were thoroughly reviewed, and critically evaluated for their relative advantages and shortcomings. It was shown that sample preparation, testing procedure, and post-processing of results can significantly affect experimental outcomes, especially the RS modulus. It is recommended that in addition to current recommendations in CEN - EN 408, Timber Structures – Structural Timber and Glued Laminated Timber – Determination of Some Physical and Mechanical Properties, further specifications should be outlined in regards to plate material and type, glue type, and, more importantly, the relative location of reference points used for deformation measurement to ensure consistent and reliable comparison of RS characteristics reported by researchers. An equation was derived, and is presented, that ensures the vertical load passes through the centroid of the inclined specimen to avoid eccentricity in the specimen and moment transfer at the base of the plates. The effect of various factors on RS properties have been reviewed.

CRISPR-mediated multiplexed live cell imaging of nonrepetitive genomic loci with one guide RNA per locus

Three-dimensional (3D) structures of the genome are dynamic, heterogeneous and functionally important. Live cell imaging has become the leading method for chromatin dynamics tracking. However, existing CRISPR- and TALE-based genomic labeling techniques have been hampered by laborious protocols and are ineffective in labeling non-repetitive sequences. Here, we report a versatile CRISPR/Casilio-based imaging method that allows for a nonrepetitive genomic locus to be labeled using one guide RNA. We construct Casilio dual-color probes to visualize the dynamic interactions of DNA elements in single live cells in the presence or absence of the cohesin subunit RAD21. Using a three-color palette, we track the dynamic 3D locations of multiple reference points along a chromatin loop. Casilio imaging reveals intercellular heterogeneity and interallelic asynchrony in chromatin interaction dynamics, underscoring the importance of studying genome structures in 4D.

Application of genetic algorithm for determining the locations of reference points of local navigation system and minimizing their number

In this paper, the problem of minimization of the number of local navigation system (LNS) reference points (RPs) and RPs’ location optimization is posed according to the criterion of ensuring the factor of geometric dilution of precision (GDOP) averaged over the space is not worse than a given one. According to authors’ best knowledge, this is the first time such a problem has been posed and solved. An approximate numerical solution to the problem based on a genetic algorithm is proposed. The effectiveness of the proposed method is assessed by simulating the placement of a different number of ranging LNS RPs in rooms of various configurations and comparing the result with the quasi-optimal result of a complete numerical search of all possible locations of the LNS anchors. The conclusion is made on the applicability of the proposed method for solving the problem and the prospects of building on its basis a tool for automating the development of positional LNS to reduce the development time and the cost of infrastructure.

Measurements and Simulation Study of Daylight Availability and Its Impact on the Heating, Cooling and Lighting Energy Demand in an Educational Building

This paper deals with the impact of the use of daylight on the overall energy demand for heating, cooling, and lighting in educational buildings. The energy performance of buildings is currently of the utmost importance as current European regulations, starting from 31st December 2020 impose that all new buildings must meet nearly zero-energy building requirements. This paper presents a study of the illuminance distribution in an educational room obtained from measurements and simulation results using two different models. One of the models, integrated with a thermal simulation software, was used to estimate the impact of daylight on the energy demand. The analysis included the use of various window types, lighting control system, reference point location, and daylight calculation model for a sample room in an educational building. Results of the analysis indicate that, due to the high share of lighting demand (reaching up to 78% of the primary energy balance), there is a need to take into account the efficiency of lighting systems during the design process to correctly determine the actual energy balance of a building, increase the quality of the design of lighting systems, as well as to select the optimal parameters of windows.

Automatic detection of anatomical landmarks of the aorta in CTA images.

Computed tomography angiography (CTA) is one of the most common vascular imaging modalities. However, for clinical use, it still requires laborious manual analysis. This study demonstrates the feasibility of a fully automated technology for the accurate detection and identification of several anatomical reference points (landmarks), commonly used in intravascular imaging. This technology uses two different approaches, specially designed for the detection of aortic root and supra-aortic and visceral branches. In order to adjust the parameters of the developed algorithms, a total of 33 computed tomography scans with different types of pathologies were selected. Furthermore, a total of 30 independently selected computed tomography scans were used to assess their performance. Accuracy was evaluated by comparing the locations of reference points manually marked by human experts with those that were automatically detected. For supra-aortic and visceral branches detection, average values of 91.8 % for recall and 98.8 % for precision were obtained. For aortic root detection, the average difference between the positions marked by the experts and those detected by the computer was 5.7 ± 7.3 mm. Finally, diameters and lengths of the aorta were measured at different locations related to the extracted landmarks. Those measurements agreed with the values reported by the literature. Graphical abstract Schematic description of the proposed algorithm. The input includes an already segmented aorta (left), there are two main sub-processes related to the detection of branches and roots (center), and the output includes the segmented original aorta with the branches and the detected landmarks superimposed (right).

Indoor Fingerprint Localization Algorithm Based on Variable Weight Using Channel State Information

In order to solve the problems of indoor fingerprint localization algorithm based on static weight, such as low positioning accuracy and poor environmental adaptability, a variable weight indoor based on channel state information with Euclidean distance as weight reference is proposed. In the preprocessing stage, the collected CSI amplitude values are first subjected to Butterworth low-pass filtering denoising processing, and then the values of each sampling point are averaged, and the reference point location fingerprint database is established by combining the known coordinates. The weight index α is introduced in the online positioning stage, and the nearest neighbor is found by the KNN algorithm with the CSI eigenvalue reference. Then the weight index β is introduced, and the Euclidean distance is used as the weight reference, and the nearest neighbor is weighted. Get the coordinates of the target position. The experimental results show that the indoor fingerprint localization algorithm proposed by this scheme has higher positioning accuracy and less fluctuation of positioning error than the traditional KNN-based indoor fingerprint localization algorithm.

Boundary characteristic orthogonal polynomials method in the vibration analysis of multi-span plates acting upon a moving mass

The Boundary Characteristic Orthogonal Polynomials (BCOP) method is used in this study in order to analyze multi-span plates traversed by a moving inertia load traveling on an arbitrary path with constant velocity. The plate is assumed to be free from any support at the longitudinal edges and the spans are made by simply supported constraints at width, i.e. SFSF. The plate's mode shapes are generated by the BCOP method while the boundary condition is satisfied over all computational modes. A free vibration analysis is done in order to find natural frequency. The governing differential equations of motion are derived by Hamilton's principle and the solution in the time domain is found by using the Matrix Exponential method after modeling the problem in state space. All of the convective inertia terms are included in the acceleration derivatives and the responses are presented both for the load moving on the plate's surface ignoring/including the mass inertia effect. A comprehensive parametric study on the plate's mid-spans is carried out for the single, two- and three-span plates, investigating Dynamic Amplification Factor (DAF) versus non-dimensional velocity (V). The effect of mass and aspect ratio along with the location of reference point of calculation on the dynamic behavior of a multi-span plate is investigated and many graphs are generated as spectra. One can easily find the critical velocity as well as the peak deflection for each case study by introducing a corrective factor. The solution under moving mass excitation is obtained by the factor if the same response for moving load is known.

Camera calibration method with checkerboard pattern under complicated illumination

Camera calibration is a key step in three-dimensional (3-D) reconstruction; however, the calibration accuracy and stability often suffer from complicated illumination in real applications. The camera calibration method using the checkerboard pattern is improved for high-precision calibration under complicated illumination. First, an improved Harris corner detector based on color constancy, as well as a subpixel optimization method based on prior knowledge of the checkerboard, are proposed to overcome the influence of bad lighting. Second, a checkerboard pattern with a central circle point is designed for better reference point location for uneven illumination. The checkerboard identification by Delaunay triangulation is also improved for the situation of discontinuity caused by over-saturation. Finally, the camera parameter optimization process is improved to reduce the calibration error produced by complicated illumination. Experimental results show that the improvements achieve more accurate and stable calibration results in complicated lighting conditions compared with traditional methods.

The problem of credibility studies on deformations of engineering objects in the geologically unstable area of Szczecin

The location of reference points in deformation studies of engineering objects is often associated with low reliability of the obtained measurement results. This concerns the lack of proper diagnosis of the geological structure of the area. The reliability of deformation measurements is also low when we obtain data that only characterize the effects and not the cause-and-effects. The authors reviewed the influence of geological conditions on the formation of deformations of some engineering objects. The reference points were located in the immediate vicinity of the facilities, without taking into account the geological structure of the areas where the facilities were located. The proposed test method is based on a three-segment control and measurement system. An example of such considerations is the engineering facilities on the Grodzka and Ostrów Grabowski Island in the Szczecin area. The basic issue is to locate geologically stable areas in the vicinity of monitored engineering objects on the basis of geological substrate assessment and to analyse archival materials concerning periodical measurements of class 1 and 2 levelling lines in the Szczecin area. Reference points are located, which constitute the first segment of the control and measurement system. Subsequent segments of the system are organized with reference to the points of the first segment. This method provides reliable data on deformations of engineering objects.

Vertical Displacements Analysis of Measurements Achieved by Laser Station

Measurements of vertical displacements using geodetic methods consist in the determination of changes in the location of reference points on the object or of its whole components. Such measurements require a high accuracy which can be ensured by the application of appropriate measuring instruments and measurement technologies. Modern measurement methods enable us to undertake tasks which traditional methods could not handle, and the required precision is guaranteed. This article describes an analysis of measurements of vertical displacements taken by means of a coordinate laser station, Leica TDRA 6000, as an alternative for measurements performed by precise levelling. An original approach to the stabilisation of measurement points is presented and technical guidelines for measurements are provided. An analysis of the data obtained from the measurements allowed us to formulate conclusions regarding the measurement technology in question and the accuracy of the results.

К вопросу развития теории базирования в машиностроении

Basic regulations of basing theory are considered, its drawbacks are emphasized. The additional concepts are offered: theoretical, actual schemes of basing, a three-point basis, a scheme of the location of reference points on the basis and changes in statements of concepts.

Improvement of Computer-Aided Manufacturing (CAM) Software for Laser Machining

In this paper, effective and user friendly CAM software is presented that automatically generates any three dimensional complex toolpaths according to a CAD drawing. In advanced manufacturing, often it is essential to scan the sample following a complex trajectory which consists of short (few microns) and multidirectional moves. The reported CAM software offers constant velocity for all short trajectory elements and provides an efficient shift of tool path direction in sharp corners of a tool trajectory, which is vital for any laser, based precision machining. The software also provides fast modification of tool path, automatic and efficient sequencing of path elements in a complicated tool trajectory, location of reference point and automatic fixing of geometrical errors in imported drawing exchange files (DXF) or DWG format files.

Novel experimental design for high pressure-high temperature electrical resistance measurements in a "Paris-Edinburgh" large volume press.

We present a novel experimental design for high sensitivity measurements of the electrical resistance of samples at high pressures (0-6 GPa) and high temperatures (300-1000 K) in a "Paris-Edinburgh" type large volume press. Uniquely, the electrical measurements are carried out directly on a small sample, thus greatly increasing the sensitivity of the measurement. The sensitivity to even minor changes in electrical resistance can be used to clearly identify phase transitions in material samples. Electrical resistance measurements are relatively simple and rapid to execute and the efficacy of the present experimental design is demonstrated by measuring the electrical resistance of Pb, Sn, and Bi across a wide domain of temperature-pressure phase space and employing it to identify the loci of phase transitions. Based on these results, the phase diagrams of these elements are reconstructed to high accuracy and found to be in excellent agreement with previous studies. In particular, by mapping the locations of several well-studied reference points in the phase diagram of Sn and Bi, it is demonstrated that a standard calibration exists for the temperature and pressure, thus eliminating the need for direct or indirect temperature and pressure measurements. The present technique will allow simple and accurate mapping of phase diagrams under extreme conditions and may be of particular importance in advancing studies of liquid state anomalies.

Rapid ranging through evaluation of image distortion

Distortion is an undesirable aberration found in optical imaging systems, necessitating numerical calibration. However, the fact that image distortion changes with observation distance can be used for ranging. This study developed a rapid, passive-ranging technique, which is simple, incurs low costs, results in minimal interference, and requires few parameters. After determining the location of reference points, the relationship between the normalized mean distortion of images and observation distance is described using two mathematical models, one of which is based on distortion theory and the other is derived from the curve fitting of the experimental results. Analyzing the instantaneous rate of image distortion can also assist in ranging. The proposed technique demonstrates high sensitivity at closer observation distances, but loses effectiveness as observation distances increase.

Sensitivity analysis and parameter estimation of heat transfer and material flow models in friction stir welding

Although numerical models of heat transfer and material flow have contributed to understand the underlying mechanisms of friction stir welding (FSW), there are certain input model parameters that can not be easily determined. Thus, the model predictions do not always agree with experimental results. In this work, sensitivity analysis and parameter estimation were applied to test heat transfer and material flow models. A forward-difference approximation was used to compute the sensitivity of the solution with respect to the unknown model parameters. The Levenberg-Marquardt (LM) method was applied to solve the nonlinear parameter estimation problem. The numerical models were developed by the finite element method (FEM). The way in which the unknown model parameters independently affect the results and the importance of the location of reference points that take part in the objective function were determined.

Adaptive subset offset for systematic error reduction in incremental digital image correlation

Digital image correlation (DIC) relies on a high correlation between the intensities in the reference image and the target image. When decorrelation occurs due to large deformation or viewpoint change, incremental DIC is utilized to update the reference image and use the correspondences in this renewed image as the reference points in subsequent DIC computation. As each updated reference point is derived from previous correlation, its location is generally of sub-pixel accuracy. Conventional subset which is centered at the point results in subset points at non-integer positions. Therefore, the acquisition of the intensities of the subset demands interpolation which is proved to introduce additional systematic error. We hereby present adaptive subset offset to slightly translate the subset so that all the subset points fall on integer positions. By this means, interpolation in the updated reference image is totally avoided regardless of the non-integer locations of the reference points. The translation is determined according to the decimal of the reference point location, and the maximum are half a pixel in each direction. Such small translation has no negative effect on the compatibility of the widely used shape functions, correlation functions and the optimization algorithms. The results of the simulation and the real-world experiments show that adaptive subset offset produces lower measurement error than the conventional method in incremental DIC when applied in both 2D-DIC and 3D-DIC.

Protein motifs retrieval by SS terns occurrences

This paper describes a new approach to the analysis of protein 3D structure based on the Secondary Structure (SS) representation. The focus is here on structural motif retrieval. The strategy is derived from the Generalized Hough Transform (GHT), but considering as structural primitive element, the triplet of SSs. The triplet identity is evaluated on the triangle having the vertices on the SS midpoints, and is represented by the three midpoints distances. The motif is characterized by the complete set of triplets, so the Reference Table (RT) has a tuple for each triplet. Tuples contain, beside the discriminant component (the three edge lengths), the mapping rule, i.e. the Reference Point (RP) location referred to the triplet. In the macromolecule to be analyzed, each possible triplet is searched in the RT and every match gives a contribution to a candidate location of the RP. Presence and location of the searched motif are certified by the collection of a number of contribution equal (obviously in absence of noise and ambiguities) to the RT cardinality (i.e. the number of motif triplets). The approach is tested on twenty proteins selected randomly from the PDB, but having a different number of SSs ranging from 14 to 46. The retrieval of all possible structural blocks composed by three, four and five SSs (very compact and completely distributed) have been conducted. The results show valuable performances for precision and computation time.