METHOD OF EXCITATION OF QUASI LONGITUDINAL ACOUSTIC WAVES IN LAYERED STRUCTURES

The analysis of methodological possibilities of excitation of quasi-longitudinal (QL) acoustic waves of the megahertz frequency range in layered structures GaN-on-sapphire is studied and carried out. Volume-type transducers polarized by plate thickness are used to generate and detect QL waves. It is concluded that quasilongitudinal modes (QL) can be excited by this method – the so-called Anisimkin (AN) waves, for which the displacement plane is localized in the film plane and the displacement direction is directed along the wave vector.

Displacement Velocity and Strain Analysis of Opak Fault Monitoring Stations

The Opak Fault is an active fault that can potentially cause earthquakes in Yogyakarta. Periodic monitoring of the Opak Fault activity was previously used more GNSS observation data from the measurement campaign by the Geodesi Geometri dan Geodesi Fisis (GGGF) Laboratory Team, Geodetic Engineering Department, Faculty of Engineering, Universitas Gadjah Mada. However, there are several CORS BIG stations located in Yogyakarta. The CORS BIG data is used to increase the precision of the Opak Fault monitoring station. Therefore, the addition of the CORS is evaluated to obtain a displacement in the monitoring station. The computation of the displacement velocity value of the Opak Fault monitoring station has been done before using the Linear Least Square Collocation and grid search methods. The other method, namely the kriging method, needs to be evaluated for producing a more precise displacement velocity value. The research data includes GNSS campaign and CORS BIG data for six years, 2013 to 2020. The CORS stations around DIY are JOGS and CBTL. The GNNS data were processed to determine the solution for the daily coordinate, displacement, and standard deviation values for each Opak Fault monitoring station. The displacement velocity value is generated by the Linear Least Square method then reduced from the influence of the Sunda Block. The velocity value is used in the strain value estimation around the Opak Fault area at each station using the kriging method combined with the gaussian sequential simulation technique. The estimated displacement velocities are examined for statistical significance compared to the research of Adam (2019) and Pinasti (2019). This research generates the value of the displacement velocity in the east and north components of 12.39 to 30.99 mm/year and 1.96 to -14.11 mm/year, respectively. The displacement direction of all monitoring stations is dominant to the southeast. The Sunda Block reduced the displacement velocity. The east and north components are -2.32 to 2.28 mm/year and -0.52 to 4.2 mm/year, respectively. The displacement direction is towards the northwest. The strain estimation using the kriging method combined with the gaussian sequential simulation technique obtained an average strain value of 0.05 microstrain/year. The result of the data processing at each station has different arrow lengths, meaning that each location has a different strain value.

THE PUSHOUT STRENGTH OF CONCRETE PAVEMENT SLAB AND CLAY SOIL LAYERS

The frictional forces between the concrete slab and base has been combined with the movements of the horizontal slab that have been induced by variations of the moisture and temperature in concrete slabs. The frictional drag that acts on the slab bottom as a result of base friction is in an opposite horizontal slab displacement direction, and resist movements of the horizontal slab. A condition of smoother interface provides lower resistance to slab movement. On the other hand, rough interfaces are beneficial in the reduction of the load-related stresses. As bonding degree between slab and foundation affects the friction that has been mobilized at interface, a realistic evaluation of friction of the interface is required for the rational designs of the concrete pavement. In this work, push-off test has been performed. Based upon results of the friction tests, the friction characteristics of concrete and soil have been researched. The parameters that influence the maximal displacement and friction coefficient are (interface state, rate of movement) for friction and (rate of movement, interface condition) for the displacements, respectively. Finally, once the applied force reaches a stable state, the frictional force increases dramatically. The most important influence on this force is the interface state, which is accompanied by movement rate. The change of the interface from a smooth to a rough surface increases the overall coefficient of friction.

A New Measurement of Anisotropic Relative Permeability and Its Application in Numerical Simulation

In this paper, we used a self-developed anisotropic cubic core holder to test anisotropic relative permeability by the unsteady-states method, and introduced the anisotropic relative permeability to the traditional numerical simulator. The oil–water two-phase governing equation considering the anisotropic relative permeability is established, and the difference discretization is carried out. We formed a new oil–water two-phase numerical simulation method. It is clear that in a heterogeneous rock with millimeter to centimeter scale laminae, relative permeability is an anisotropic tensor. When the displacement direction is parallel to the bedding, the residual oil saturation is high and the displacement efficiency is low. The greater the angle between the displacement direction and the bedding strike, the lower the residual oil saturation is, the higher the displacement efficiency is, and the relative permeability curve tends towards a rightward shift. The new simulator showed that the anisotropic relative permeability not only affects the breakthrough time and sweep range of water flooding, but also has a significant influence on the overall water cut. The new simulator is validated with the actual oilfield model. It could describe the law of oil–water seepage in an anisotropic reservoir, depict the law of remaining oil distribution of a typical fluvial reservoir, and provide technical support for reasonable injection-production directions.

Prediction of Mean Responses of RC Bridges Considering the Incident Angle of Ground Motions and Displacement Directions

Inelastic dynamic analyses were carried out using 3D and 2D models to predict the mean seismic response of four-span reinforced concrete (RC) bridges considering directionality effects. Two averaging methods, including an advanced method considering displacement direction, were used for the prediction of the mean responses to account for different incident angles of ground motion records. A method was developed to predict the variability of the mean displacement predictions due to variability in the incident angles of the records for different averaging methods. When the concepts of averaging in different directions were used, significantly different predictions were obtained for the directionality effects. The accuracy of the results obtained using 2D and 3D analyses with and without the application of the combination rules for the prediction of the mean seismic demands considering the incident angle of the records was investigated. The predictions from different methods to account for the records incident angles were evaluated probabilistically. Recommendations were made for the use of the combination rules to account for the directivity effects of the records and to predict the actual maximum displacement, referred to as the maximum radial displacement.

Investigating the effects of combinations of irregularities on seismic ductility demands and mean response for four-span RC bridges considering displacement direction

The effects of combinations of different types of irregularities have not been studied in details in the past and current seismic design codes do not address this issue appropriately. In this research, 76 regular and irregular bridges with irregularities in both superstructure and substructure were designed and evaluated to investigate the impact of combinations of irregularities on the seismic ductility demands. The irregularity parameters considered in this study include irregularities in span arrangement, different lengths of columns, different abutments support conditions and different stiffness of superstructure. The bridges were designed and checked according to AASHTO provisions. Inelastic time history analysis was conducted using OpenSees software and ductility demands in bridge columns for different bridge configurations were predicted. Predictions of ductility demands were based on the mean responses obtained using a number of ground motion records. Finally, the effect of considering displacement directions in predicting the mean bridge response (i.e., using different methods for predicting the mean response) for irregular and regular bridges was investigated. The results indicate that the combinations of irregularities can significantly increase the ductility demands in some cases compared to the case of regular bridges.

A Time-Motion Analysis of the Cross-Over Step Block Technique in Volleyball: Non-Linear and Asymmetric Performances

Blocking performance in volleyball is strongly affected by the time in which the action is executed. This study analyzes the time-motion variables in terms of the player’s role and movement direction (right or left), in different phases of the displacement and jump actions in the cross-over step block technique. A kinematic analysis was conducted with 10 senior male volleyball players. Two series of five repetitions were each recorded and classified in terms of middle-blockers (block in the center and sides of the net) and wing-players (only block in the sides). The results showed that the middle-blockers were significantly slower than the wing-players in the first (0.75 ± 0.24 vs. 0.66 ± 0.19 sec; p = 0.020; ES = −0.37 ± 0.30) and fourth phases (0.33 ± 0.8 vs. 0.29 ± 0.8 sec; p = 0.001; ES = −0.44 ± 0.31), and in the total time for blocking (3.15 ± 0.6 vs. 3 ± 0.58 sec; p = 0.003; ES = −0.23 ± 0.31). Overall, players were significantly faster when moving to the right side, showing performance asymmetries. The fastest phases were also performed just before the jump. These findings provide specific knowledge about the cross-over step block technique in its different phases and displacement direction. This information can be used to improve the movement time in the first defensive action in volleyball.

A Vision-Based Method for Determining Aircraft State during Spin Recovery

This article proposes a vision-based method of determining in which of the three states, defined in the spin recovery process, is an aircraft. The correct identification of this state is necessary to make the right decisions during the spin recovery maneuver. The proposed solution employs a keypoints displacements analysis in consecutive frames taken from the on-board camera. The idea of voting on the temporary location of the rotation axis and dominant displacement direction was used. The decision about the state is made based on a proposed set of rules employing the histogram spread measure. To validate the method, experiments on flight simulator videos, recorded at varying altitudes and in different lighting, background, and visibility conditions, were carried out. For the selected conditions, the first flight tests were also performed. Qualitative and quantitative assessments were conducted using a multimedia data annotation tool and the Jaccard index, respectively. The proposed approach could be the basis for creating a solution supporting the pilot in the process of aircraft spin recovery and, in the future, the development of an autonomous method.

Reverse fracture displacement direction closed reduction technique (RCRT) for the treatment of valgus impacted femoral neck fracture

Background Impacting locked in fracture site of valgus impacted femoral neck fracture may be the difficulty to achieve anatomical reduction. The aim of this article is to introduce a novel technique to successful complete anatomical reduction. Methods After identify the fracture classification and displace direction. Two 2.0 mm diameter kirschners wire were inserted crossing the femoral head and fixed into acetabular bone. under the continuous image guiding and monitoring, reversing fracture displacement direction with internal rotation and abduction of the hip to complete the closed reduction. results anatomical reduction was achieved in X-ray and CT data postoperative. conclusions This technique provides anatomical reduction, simple procedure, and few interference of internal environment of hip and fracture site in valgus impacted femoral neck fracture.