Diagonal Displacement Research Articles

Member control efficiency and shape control capability of a loaded cable dome

In this paper, the control efficiency of the members and shape control ability of a loaded adaptive cable dome consisting of 16 cables and 4 struts are investigated. The structure uses specially designed cables and electric telescopic struts integrated with an actuation control system, and all members of the structure are length-adjustable. Initially, an intelligent algorithm is employed to solve the structural shape optimization control model, thereby determining the optimal adjustment amounts. Subsequently, active adjustment and active control tests are conducted to evaluate the control efficiency of the members and the shape control capabilities of the cable dome. The results indicate that the ridge and diagonal cables exhibit the most effective control, followed by the upper and lower hoop cables, while the struts show the lowest control efficiency, primarily influencing the displacement of the joints at their two ends. Moreover, the cables' internal force control efficiency is 3–4 times higher than that of the struts. The ridge and diagonal cables' internal force and displacement control efficiency is about 1.5 times higher than that of the upper and lower hoop cables. The loaded test model exhibits the ability to restore the vertical coordinates of upper joints to their target coordinates, while reducing the internal forces of the components by at least 15 %, and the shape control capability of the structure can be enhanced by incorporating various types of active units. The measured values correlate well with the simulation results, validating the accuracy of the simulations.

Multichannel Ka-Band Microwave Oscillator Based on Frequency-Shifted Relativistic Backward-Wave Oscillators

Experiments on summation of linearly polarized Gaussian wave beams in free space from two and four synchronous nanosecond Ka-band relativistic backward wave oscillators (BWOs), each having an output power of about 200 MW with controllably shifted oscillator frequencies have been carried out. An about 0.5% frequency shift in one of the channels was equivalent to a one-period phase delay of the carrier frequency. In a two-channel version of the device, a full beat cycle was obtained for a pulse with quadratic (with respect to the number of sources) enhancement of the power flux density at the interference maximum of the integral directional pattern (DP). In the case of a four-channel device, a diagonal displacement of the DP lobes has been demonstrated.

The Effect of Optic Disc Center Displacement on Retinal Nerve Fiber Layer Measurement Determined by Spectral Domain Optical Coherence Tomography.

PurposeTo investigate the effect of optic disc center displacement on retinal nerve fiber layer (RNFL) measurement determined by spectral domain optical coherence tomography (SD-OCT).MethodsThe optic disc center was manipulated at 1-pixel intervals in horizontal, vertical, and diagonal directions. According to the manipulated optic disc center location, the RNFL thickness data were resampled: (1) at a 3.46-mm diameter circle; and (2) between a 2.5-mm diameter circle and 5.4-mm square. Error was calculated between the original and resampled RNFL measurements. The tolerable error threshold of the optic disc center displacement was determined by considering test-retest variability of SD-OCT. The unreliable zone was defined as an area with 10% or more variability.ResultsThe maximum tolerable error thresholds of optic disc center displacement on the RNFL thickness map were distributed from 0.042 to 0.09 mm in 8 directions. The threshold shape was vertically elongated. Clinically important unreliable zones were located: (1) at superior and inferior region in the vertical displacement; (2) at inferotemporal region in the horizontal displacement, and (3) at superotemporal or inferotemporal region in the diagonal displacement. The unreliable zone pattern and threshold limit varied according to the direction of optic disc displacement.ConclusionsOptic disc center displacement had a considerable impact on whole RNFL thickness measurements. Understanding the effect of optic disc center displacement could contribute to reliable RNFL measurements.

Face-Diagonal 방법 기반의 레이저 간섭계 측정을 이용한 CMM 의 직각도 추정

The out-of-squareness is one of the error sources that affect the positioning accuracy of machine tools and coordinate measuring machines. Laser interferometer is widely used to measure the position and angular errors, and can measure the squareness using an optical square. However, the squareness measurement using the laser interferometer is difficult, as compared to other errors due to complicated optics setup and Abbe’s error occurrence. The effect of out-of-squareness mainly appears at the face-diagonal of the movable plane. The diagonal displacements are also affected by the position dependent geometric errors. In this study, the squareness estimation techniques via diagonal displacement measurement using the laser interferometer without an optical square were proposed. For accurate estimation and measurement time reduction, the errors selected from proposed discriminant were measured. Discrepancy between the proposed technique with the laser interferometer (with an optical square) result was 0.6 µrad.

Topology optimization of supporting structure for seismic response reduction of an arch

A flexible supporting structure that reduces seismic response of an arch is proposed. Topology and cross-sectional areas of the supporting structure modeled as a truss structure are optimized through two steps of static and dynamic optimization problems. In the first step, a flexible supporting structure that has diagonal displacement at the top under horizontal load is obtained by solving static optimization problems. Then, in the second step, the cross-sectional area of the flexible member is optimized to minimize the seismic response acceleration of the arch evaluated by the complete quadratic combination (CQC) method. Time-history seismic response analysis is carried out to show that the response in the normal direction of the roof successfully decreases due to flexibility of the supporting structure; in addition, installing passive energy dissipation devices into the flexible supporting structure is very effective in reducing the tangential response of the arch.

Quantifying the spatial extent of the corollary discharge benefit to transsaccadic visual perception.

Extraretinal information, such as corollary discharge (CD), is hypothesized to help compensate for saccade-induced visual input disruptions. However, support for this hypothesis is largely for one-dimensional transsaccadic visual changes, with little comprehensive information on the spatial characteristics. Here we systematically mapped the two-dimensional extent of this compensation by quantifying the insensitivity to different displacement metrics. Human subjects made saccades to targets positioned at different amplitudes (4° or 8°) and directions (rightward, oblique, or upward). After the saccade the initial target disappeared and, after a blank period, reappeared at a shifted location-a collinear, diagonal, or orthogonal displacement. Subjects reported the perceived shift direction, and we determined the displacement detection based on the perceptual judgments. The two-dimensional insensitivity fields resulting from the perceptual thresholds had spatial features similar to the saccadic eye movement variability: 1) scaled with movement amplitude, 2) oriented (less sensitive to the change) along the saccade vector, and 3) approximately constant in shape when normalized by movement amplitude. In addition, comparing the postsaccadic perceptual estimate of the presaccadic target location to that based solely on the postsaccade visual error showed that overall the perceptual estimate was approximately 50% more accurate and 35% less variable than estimates based solely on this visual information. However, this relationship was not uniform: The benefit of extraretinal information was observed largely for displacements with a component parallel to the saccade vector. These results suggest a graded use of extraretinal information when forming the postsaccadic perceptual evaluation of transsaccadic environmental changes.

Two Important Issues Relevant to Torsional Response of Asymmetric 8-Story RC Building Designed with Direct Displacement based Design Approach

Direct displacement based design (DDBD) is a conceptual framework that directly design a structure to achieve an expected performance level under specified seismic intensity. In this study, two important issues relevant to torsional response of mass eccentric 8-story RC building designed with DDBD approach are investigated. These issues are including the effects of unbalanced mass distribution scenario on the torsional response parameters and the study of these parameters with reference to diagonal displacement. Diagonal displacement is the SRSS combination of the displacement demands along the direction of excitation and orthogonal direction. Three different unbalanced mass distribution scenarios which produce the same mass eccentricity were applied to the plan of the generic structural model to determine the general range of the mass moment of inertia (MMI) variation due to different unbalanced mass distribution scenarios. Expressions were established to correlate MMI and mass eccentricity in each scenario. Results show for slight eccentricities the variation of the MMI is negligible but as eccentricity is increased the range of the variation is extended. Then sensitivity analyses based on finite element method and inelastic time history analysis have been carried out on 8-story RC building frame designed with DDBD approach with different level of mass eccentricity and different MMI. Torsional response parameters in terms of maximum displacement demands of edge elements, maximum diaphragm rotation, maximum nominal relative displacement and maximum nominal rotation is compared with considering diagonal and horizontal displacement demands along seismic excitation.

Natural Convection in a Square Enclosure with a Square Heat Source at Different Horizontal and Diagonal Eccentricities

The present article aims to extend a previous numerical study on the natural convection process in a square enclosure with a vertical eccentric square heat source (cylinder) [1]. Here, we investigated buoyancy-induced convective flow and heat transfer for horizontal and diagonal eccentric displacement in a square cylinder. Numerical studies are performed for Rayleigh numbers in the range 103–106, using our recently developed flexible forcing IB–thermal lattice Boltzmann method scheme [1]. Detailed analysis of isotherms, streamlines, and Nusselt number distribution as functions of Rayleigh number and eccentricity is provided in this paper.

Analysis of Fraction Skill Score properties for a displaced rainy grid point in a rectangular domain

The Fraction Skill Score (FSS) is a recently developed and popular metric used for precipitation verification. A compact analytical expression for FSS is derived for a case with a single displaced rainy grid point in a rectangular domain. The existence of an analytical solution is used to determine some properties of FSS, which might also be applicable in other cases since the rain areas of any shape will asymptote towards this solution if the displacement is sufficiently large. The use of the simple square shape of the neighborhood causes the FSS value to be dependent on the direction of the displacements (not only on the displacement size). The effect is limited in scope but can increase or decrease the FSS value by 0.1. Moving a nearby border closer to the rainy points can either increase or decrease the FSS value, depending on the location of the border. The FSS value near a border can be at most 33% larger than the FSS value in the infinite domain, assuming the same neighborhood size and displacement. The effect of the nearby corner is similar to the effect of the nearby border but is stronger. The useful forecast criteria (FSSuseful) is defined as a value of FSS for a precipitation feature with a displacement half the neighborhood size. FSSuseful for a displaced rainy grid point depends on the orientation of the displacement being the largest for displacements that are parallel to the borders and the smallest for a diagonal displacement for which the value can be as low as 0.42. An analysis of a real dataset was also performed, which showed that the border effect is usually small, but in some cases the effect becomes large (an increase of FSS value up to 70% was identified). The likelihood of a strong border effect in real datasets increases significantly if the neighborhood size at FSS=0.5 is comparable or larger than the domain size.

Experimental study of the vortex-induced vibration of drilling risers under the shear flow with the same shear parameter at the different Reynolds numbers.

A considerable number of studies for VIV under the uniform flow have been performed. However, research on VIV under shear flow is scarce. An experiment for VIV under the shear flow with the same shear parameter at the two different Reynolds numbers was conducted in a deep-water offshore basin. Various measurements were obtained by the fiber bragg grating strain sensors. Experimental data were analyzed by modal analysis method. Results show several valuable features. First, the corresponding maximum order mode of the natural frequency for shedding frequency is the maximum dominant vibration mode and multi-modal phenomenon is appeared in VIV under the shear flow, and multi-modal phenomenon is more apparent at the same shear parameter with an increasing Reynolds number under the shear flow effect. Secondly, the riser vibrates at the natural frequency and the dominant vibration frequency increases for the effect of the real-time tension amplitude under the shear flow and the IL vibration frequency is the similar with the CF vibration frequency at the Reynolds number of 1105 in our experimental condition and the IL dominant frequency is twice the CF dominant frequency with an increasing Reynolds number. In addition, the displacement trajectories at the different locations of the riser appear the same shape and the shape is changed at the same shear parameter with an increasing Reynolds number under the shear flow. The diagonal displacement trajectories are observed at the low Reynolds number and the crescent-shaped displacement trajectories appear with an increasing Reynolds number under shear flow in the experiment.

Flexure and Shear Deformation of GFRP-Reinforced Shear Walls

AbstractExperimental results of midrise RC shear walls under quasistatic cyclic loading were used to investigate the interaction of flexural and shear deformations. Four large-scale shear walls—one reinforced with steel bars and three totally reinforced with glass fiber–reinforced polymer (GFRP) bars—were tested to failure where the behavior was dominated by flexure. It was found that relying on the diagonal displacement transducers tended to overestimate shear deformations by 30 to 50%. To correct the shear deformations, the center of rotation of the tested shear walls was evaluated. Based on experimental results, the fundamental equation of flexural deformation obtained values of the center of rotation (α). Using the suggested values of α produced consistent results for the flexure and shear deformations. Decoupling the total deformation of the tested shear walls into flexural and shear deformations was discussed. Using elastic materials (GFRP bars) gave uniform distributions of shear strains along the ...

A new formulation of laser step diagonal measurement—Three-dimensional case

The laser step-diagonal measurement modifies the diagonal displacement measurement by executing a diagonal as a sequence of single-axis motions. It has been claimed that the step-diagonal test enables the identification of all the volumetric error components, including linear errors, straightness and squareness errors, in three-dimensional space. In this paper, we show that the conventional formulation of the step-diagonal measurement is valid only when implicit assumptions related to the configuration of laser and mirror setups are met, and that its inherent problem is that it is generally not possible to guarantee these conditions when volumetric errors of the machine is unknown. To address these issues, we propose a new formulation of the step-diagonal measurement, in order to accurately identify volumetric errors even under the existence of setup errors. To simplify the discussion, this paper only considers the two-dimensional version of laser step-diagonal measurement to estimate volumetric errors on the XY plane. The effectiveness of the proposed modified identification scheme is experimentally investigated by an application example of two-dimensional laser step diagonal measurement to a high-precision machine tool.

A regular grid imposes a city-block metric on visual space

Purpose. To measure the metric imposed on visual space by the processes that group a grid of points into rows and columns. Method. On each trial the observer viewed (for 200 ms) a grid of small dots (Gaussian blobs), some of which were displaced from their expected locations. On any given trial, either 84 or 108 dots were perturbed, and the subject judged, with feedback, which type of grid had been presented. Dot perturbations all had length equal to 18.75% of the horizontal inter-dot distance but varied in direction over the 16 angles, 0, 22.5, 45, …, 237.5 deg. There were thirty conditions using different histograms of displacement directions, with prescribed displacements assigned randomly to grid-dots on a given trial. From the data we estimate the average impact (in multiples of d') exerted on judgments by displacements in different directions. We take these impacts to reflect the distances in visual space traversed by different displacements. In Expt. 1 the mean grid was 16 by 16, with equal horizontal and vertical spacing. In Expt. 2, the mean grid had 11 rows and 14 columns, with rows 1.25 times farther apart than columns. Results & Conclusions. In Expt. 1, the visual distance traversed by a displaced dot was found to be equal to the sum of the separate distances traversed by the dot in the horizontal and vertical directions. Thus, for example, a diagonal displacement exerted sqrt(2) times the impact of a vertical displacement. We conclude that a regular grid of points imposes a city-block metric on visual space. When rows were 25% farther apart than columns, displacements closer to horizontal than diagonal obeyed a city-block metric as observed in Expt. 1. However, displacements ranging from diagonal up to vertical did not: the visual distance traversed by such a displacement depended only on its vertical projection.

自然発症した披裂軟骨脱臼症の１例

Dislocation of the arytenoid cartilage occurs following medical instrumentation involving the laryngeal cavity or laryngeal injury from outside the larynx. We reported a case of spontaneously posterior dislocation of the arytenoid cartilage. A 53 year-old man suffering from suddenly recurring aphonia and its improvement many over 3 months without laryngeal injury or inducement eventually ceased to improve. Laryngoscopic findings showed that the left vocal fold was tensely prolonged and the vocal process of the arytenoid cartilage on the left side was dislocated posterolaterally. X-ray videofluorography of the larynx on repetitive phonation of /he/ showed abnormally high and diagonal displacement of the vocal fold and the upper structure of the arytenoid cartilage on the left side. Palpating the cricoarytenoid joint on the left side showed abnormal swelling with tenderness. Electomyography of the intrinsic laryngeal muscle on the left side showed normal action potential. From these findings, we diagnosed his voice disorder as spontaneously posterior dislocation of the arytenoid cartilage. We manually reduced it by pulling up a balloon inserted from the piriform sinus of the affected side to the esophagus.

Real-Time Error Compensation Technique and Its Application on NC Machine Tools

This paper presents the method and process of the real-time error compensation (RTEC) on NC machine tools, which includes: identification and measurement of error components, separating and modeling of geometric-thermal error components, geometric-thermal volumetric error synthesis model, compensation control system, performance evaluation of error compensation by the body diagonal displacement measurement, and the industry application of real-time error compensation. The technique has been successfully applied to many different NC machine tools in the plants for practical production, and the machining accuracy of the NC machine tools is improved by an order of magnitude with low cost.

A theoretical analysis of 4 body diagonal displacement measurement and sequential step diagonal measurement

The introduction of B5.54 and ISO230-6 machine tool performance measurement standards are increasing the popularity of laser interferometer diagonal, sequential step diagonal or vector technique for the calibration and compensation of machine tool errors. Reported here is a theoretical analysis of the 4 body diagonal displacement measurement, sequential step diagonal or vector technique, and 3 axes linear displacement measurement. The relations between the 21 rigid body machine positioning errors and the 4 body diagonal displacement measurement; and the sequential step diagonal measurement; and the 3 axes linear displacement measurement were derived. Based on these relations, the advantages and limitations of these measurements have been analyzed.

Geometric error calibration of multi-axis machines using an auto-alignment laser interferometer

This work will report the development and application of an auto-alignment laser interferometer system for the geometric error calibration of CNC multi-axis machines. The system is capable of a diagonal displacement measurement, where multiple machine axes are moved simultaneously, with automatic optic alignment. This capability provides a solution for quick evaluation of the overall volumetric error of a multi-axis machine tool. One application of the system is that the 21 geometric errors of a 3-axis machine can be quickly estimated from the displacement measurements of some determined diagonal lines in the working volume. Compared with a time of several days using a conventional laser interferometer system, it takes only 1 hour for the proposed system to complete the geometry calibration of a 3-axis machine. A method for the roll calibration of a vertical axis is also proposed and demonstrated in this work.

An application of real-time error compensation on a turning center

A real-time error compensation (RTEC) system is developed to correct thermally-induced and geometric errors on a four-axis dual-spindle turning center. These errors vary with different cutting tool positions as well as different thermal conditions, thus real-time correction is required. Two problems in the current RTEC approach are addressed: (1) the difficulty in the actual measurement of error components according to the defined coordinates and (2) the selection of a small set of appropriate temperature variables from numerous candidate thermal sensors on a machine structure. A flexible error measurement method and an optimal temperature variable selection process are proposed to overcome these difficulties. After machine errors were characterized and modeled, the effectiveness of the developed RTEC system was evaluated by using laser inspection and an actual cutting test. The maximal diagonal displacement error is corrected from 75.0 to 7.5 μm. In the cutting test, the part diameter error of a car steering joint is reduced from 60 to 10 μm.

Interim Checks For Machine Tools

Interim checks of machine tools allow preventative maintenance and are a basis for quality assurance in manufacturing. Interim checks should be fast, and therefore fast checks, like the diagonal displacement test, are introduced. Another possibility for interim checks is the manufacturing of standardized test pieces. Possibilities with the ISO test piece for machining centres are discussed. Standardized test pieces or just elements of test pieces or fast and comprehensive tests will give manufacturers more information on their machine tools at lower costs. 1 Why interim checks? The aim of interim checks is to monitor the performance of the machine tool and to recognize any changes in the performance. An optimum monitoring of the machine tool allows machine maintenance before workpieces are out of tolerance or before a mechanical breakdown occurs. On universal NC machine tools programming errors can cause crashes, after those an interim check may provide information on whether the crash caused any damage to the machine. On a single purpose machine tool the periodic check of the workpiece gives the necessary information on the performance of the machine and on any changes in its performance. On a universal machine tool, like a machining centre or a turning centre, the workpieces produced can have significant different features. Transactions on Engineering Sciences vol 16, © 1997 WIT Press, www.witpress.com, ISSN 1743-3533