A Dynamic Method to Predict the Earthquake-Triggered Sliding Displacement of Slopes

The earthquake-induced permanent displacement is an important index of the potential damage to a slope during an earthquake. The Newmark method assumes that a slope is a rigid-plastic body, and the seismic responses of sliding masses or seismic forces along the slide plane are ignored. The decoupled method considers no relative displacement across the sliding plane, so it overpredicts the seismic response of the sliding mass. Both dynamic and sliding analyses are performed in the coupled method, but when Ts/Tm is large, the results are unconservative. In this paper, a method is proposed to predict the earthquake-triggered sliding displacement of slopes. The proposed method is based on the Newmark rigid method, coupled method, and decoupled method considering both the forces at the sliding interface and the system dynamics under critical conditions. For the flexible system, the displacements are calculated with different stiffness values, and the results show that as the stiffness increases and tends to infinity, the critical acceleration and displacements of the proposed method are close to those of the Newmark method. The proposed method is also compared with the Newmark method with the period ratio Ts/Tm. At small values of Ts/Tm, the flexible system analysis results of the displacement are more conservative than those of the rigid block model; at larger values of Ts/Tm, the rigid block model is more conservative than the flexible system.

The Effects of Steering Locomotion on User Preference and Accuracy in Virtual Environments

Locomotion in virtual environments presents challenges due to the discrepancy between the virtual and the real-world space. Teleportation has been suggested for rapid transit and low cybersickness. However, users often find the method disorienting and difficult over short distances. This is problematic in many gaming scenarios where moderate distances are common. We examined three methods of self-directed, steering locomotion for short to mid-range distances. The methods were pointing, head, and semi-decoupled head and controller. The decoupled method was to explore if game console navigation would be preferred due to familiarity. The experiment focused on user preference and accuracy and had 19 participants. We anticipated that more intuitive methods would be preferred. The pointing method had the greatest impact on accuracy. History of motion sickness susceptibility and prior use of video games did not affect preference with participants favoring the pointing method twice as often over the head method and with none preferring the semi-decoupled method. The pointing method also had lower average illness scores, although not statistically significant. The results suggest that pointing provides an accurate method of locomotion while also being a lower cybersickness option for steering navigation.

A Robotic System with Robust Remote Center Motion Constraint for Endometrial Regeneration Surgery

Surgical robots have been widely used in various surgeries in order to improve and facilitate the surgeries. However, there is no robot intended for endometrial regeneration surgery which is a new therapy to restore women’s fertility by using stem cells. Endometrial regeneration surgery requires processing endometrium and transplanting stem cells with the minimal trauma to uterus. In this paper, we introduce a surgical robotic system which consists of a dexterous hysteroscope, a supporting arm and additional novel instruments to facilitate the operations and decrease trauma to the uterus. To protect the cervix of the uterus, remote center of motion (RCM) constraint is required. First, the supporting arm and the hysteroscope are controlled separately in kinematics in order to ensure that the RCM constraint and the hysteroscope’s shape and posture are predictable. Then, a task decoupled method is used to improve the robustness of the RCM constraint. The experiments show that our method is more robust and achieves higher accuracy of RCM. Besides, the master slave control of robot with RCM constraint is also verified.

Capacitive versus Overlap Decoupling of Adjacent Radio Frequency Phased Array Coil Elements: An Imaging Robustness Comparison When Sample Load Varies for 3 Tesla MRI

Phased array (PA) receive coils are built such that coil elements approximate independent antenna behavior. One method of achieving this goal is to use an available decoupling method to decouple adjacent coil elements. The purpose of this work was to compare the relative performance of two decoupling methods as a function of variation in sample load. Two PA receive coils with 5 channels (5-ch) each, equal outer dimensions, and formed on 12 cm diameter cylindrical phantoms of conductivities 0.3, 0.6, and 0.9 S/m were evaluated for relative signal-to-noise ratio (SNR) and parallel imaging performance. They were only tuned and matched to the 0.6 S/m phantom. Simulated and measured axial, sagittal, and coronal 5-ch PA coil SNR ratios were compared by dividing the overlap by the capacitive decoupled coil SNR results. Issues related to the selection of capacitor values for the two decoupling methods were evaluated by taking the ratio of the match and tune capacitors for large and small 2 channel (2-ch) PA coils. The SNR ratios showed that the SNR of the two decoupling methods were very similar. The inverse geometry-factor maps showed similar but better overall parallel imaging performance for the capacitive decoupled method. The quotients for the 2-ch PA coils’ maximum and minimum capacitor value ratios are 3.28 and 1.38 for the large and 3.28 and 2.22 for the small PA. The results of this paper demonstrate that as the sample load varies, the capacitive and overlap decoupling methods are very similar in relative SNR and this similarity continues for parallel imaging performance. Although, for the 5-ch coils studied, the capacitive decoupling method has a slight SNR and parallel imaging advantage and it was noted that the capacitive decoupled coil is more likely to encounter unbuildable PA coil configurations.

Study of Power System Load Flow Using FPGA and LabVIEW

The capability to rapidly execute the power flow (PF) calculations permit engineers in assured with stay bigger assured within the dependability, protection, and economical operation of their system within the case of planned or unplanned instrumentality failures. The purpose of this work is to investigate the use of FPGA characteristics to speed up power flow computing time for the on-line monitoring system of a power system. The work comprises which is the development of the Power flow program using the Fast-decoupled method based on FPGA (Field Programmable Gate Array), and LABVIEW (graphical programming environment). The program delivered very satisfactory results to solve a 30-bus test system. These findings suggest that in general that differences between the proposed work and the conventional fast decoupled method are satisfactory. As for the execution time, because the FPGA uses parallel solutions, the performance of the proposed method is faster. Also, the engagement of the FPGA and the LabVIEW program presented an effective monitoring system for observing the power system.