Comparison of diagnostic accuracy of 2D and 3D measurements to determine opportunistic screening of osteoporosis using the proximal femur on abdomen-pelvic CT

Objectives To compare the osteoporosis-predicting ability of computed tomography (CT) indexes in abdomen-pelvic CT using the proximal femur and the reliability of measurements in two- and three-dimensional analyses. Methods Four hundred thirty female patients (age range, 50–96 years) who underwent dual-energy X-ray absorptiometry and abdominal-pelvic CT within 1 month were retrospectively selected. The volumes of interest (VOIs) from the femoral head to the lesser trochanter and the femoral neck were expressed as 3DFemur. Round regions of interest (ROIs) of image plane drawn over the femoral neck touching the outer cortex were determined as 2Dcoronal. In HU histogram analysis (HUHA), the percentages of HU histogram ranges related to the ROI or VOI were classified as HUHAFat (<0 HU) and HUHABone (126 HU≤). Diagnostic performance, correlation analysis and measurement reliability were analyzed by receiver operating characteristic curves, correlation coefficient and interobserver correlation coefficient (ICC), respectively. Results AUCs of each HUHA and mean-HU measurement on 2D-ROI and 3D-VOI were 0.94 or higher (P < 0.001). Both 3DFemur-Mean-HU and 3DFemur-HUHABone showed the highest AUC (0.96). The cut-off value of 3DFemur-Mean-HU was 231HU or less, (sensitivity: 94.8%; specificity: 85.0%; correlation coefficient: −0.65; P <0.001) for diagnosis of osteoporosis. There was no superiority between AUCs in 2D-ROI and 3D-VOI measurements (P > 0.05). Reliability of the 3D-VOI measurement showed perfect agreement (ICC ≥ 0.94), and 2D-ROI showed moderate to good agreement (ICC range: 0.63~0.84). Conclusions CT indexes on 3D-VOI for predicting femoral osteoporosis showed similar diagnostic accuracy with better reproducibility of measurement, compared with 2D-ROI.

Image-based visual servoing with depth estimation

For the depth estimation problem in the image-based visual servoing (IBVS) control, this paper proposes a new observer structure based on Kalman filter (KF) to recover the feature depth in real time. First, according to the number of states, two different mathematical models of the system are established. The first one is to extract the depth information from the Jacobian matrix as the state vector of the system. The other is to use the depth information and the coordinate point information of the two-dimensional image plane as the state vector of the system. The KF is used to estimate the unknown depth information of the system in real time. And an IBVS controller gain adjustment method for 6-degree-of-freedom (6-DOF) manipulator is obtained using fuzzy controller. This method can obtain the gain matrix by taking the depth and error information as the input of the fuzzy controller. Compared with the existing works, the proposed observer has less redundant motion while solving the Jacobian matrix depth estimation problem. At the same time, it will also be beneficial to reducing the time for the camera to reach the target. Conclusively, the experimental results of the 6-DOF robot with eye-in-hand configuration demonstrate the effectiveness and practicability of the proposed method.

Design and Development of an Automated Dual-Mode Microscopic System Using Electrically Tunable Lenses

Maintaining telecentricity and zooming in microscopic systems with prolonged depths of focus is a difficult challenge because these properties degrade while moving to different axial planes in the extended focal depth. In this paper, we propose the proof of concept for an automated dual-mode microscopic system that combines two electrically tunable lenses (ETLs) with a variable numerical aperture controller placed. It acts as a viable solution to allow both multiplane microscopic zooming and telecentricity with consistent image resolution throughout the objective's extended focal depth. The image plane remains fixed for both the modes of operation, namely telecentricity and multiplane zooming. To validate the performance of the proposed idea, both simulations and experiments are carried out at various ETL curvature ranges. Over the whole zoom distance range, the experimental zoom ratio is determined to range from −2.723X to −34.42X. The experimental and simulation findings are compared and found to be quite similar, with magnification error percentages of 2.26% for zoom mode and 1.27% for telecentric mode. The comprehensive explanation of simulation and experimental results demonstrate the feasibility of the proposed method for both multiplane zoom and telecentric operations on a single platform in microscopic applications.

Autonomous UAV System for Cleaning Insulators in Power Line Inspection and Maintenance

The inspection and maintenance tasks of electrical installations are very demanding. Nowadays, insulator cleaning is carried out manually by operators using scaffolds, ropes, or even helicopters. However, these operations involve potential risks for humans and the electrical structure. The use of Unmanned Aerial Vehicles (UAV) to reduce the risk of these tasks is rising. This paper presents an UAV to autonomously clean insulators on power lines. First, an insulator detection and tracking algorithm has been implemented to control the UAV in operation. Second, a cleaning tool has been designed consisting of a pump, a tank, and an arm to direct the flow of cleaning liquid. Third, a vision system has been developed that is capable of detecting soiled areas using a semantic segmentation neuronal network, calculating the trajectory for cleaning in the image plane, and generating arm trajectories to efficiently clean the insulator. Fourth, an autonomous system has been developed to land on a charging pad to charge the batteries and potentially fill the tank with cleaning liquid. Finally, the autonomous system has been validated in a controlled outdoor environment.

Multi-Frequency Image Completion via a Biologically-Inspired Sub-Riemannian Model with Frequency and Phase

We present a novel cortically-inspired image completion algorithm. It uses five-dimensional sub-Riemannian cortical geometry, modeling the orientation, spatial frequency and phase-selective behavior of the cells in the visual cortex. The algorithm extracts the orientation, frequency and phase information existing in a given two-dimensional corrupted input image via a Gabor transform and represents those values in terms of cortical cell output responses in the model geometry. Then, it performs completion via a diffusion concentrated in a neighborhood along the neural connections within the model geometry. The diffusion models the activity propagation integrating orientation, frequency and phase features along the neural connections. Finally, the algorithm transforms the diffused and completed output responses back to the two-dimensional image plane.

Impact angle guidance law to prevent the detection degradation of a seeker

An impact angle control guidance (IACG) law applicable to a homing missile equipped with a strapdown imaging seeker is investigated against a stationary target. Given an impact angle constraint, usually a detour is generated and the change of the look angle is inevitable. A rapid change of the look angle can cause a fast relative target motion in the seeker’s image plane, which can lead to a motion blur effect. The main contribution of the paper is that an IACG law is designed to minimize the look angle rate to prevent the loss of the target signal. Based on the variational approach, the optimal look angle rate that satisfies the impact angle constraint is derived, and the guidance law is designed to follow the optimal look angle rate. Using various weighting functions, a guidance law that has low sensitivity to the initial condition is also developed. Numerical simulation supports the performance of the guidance law. The result illustrates that the proposed guidance law reduces the rate of look angle in comparison with other IACG laws.

Kinematic projection in modern technologies

The trajectories and coordinates of unmanned aircrafts spatial location determination is researched with the help of kinematic projection means. The methodology offered below considers the formation of two mobile and independent kinematic projection centers raised into the air by drones. The electromagnetic radio waves emitted by them, penetrating an unknown aircraft object, form two independent projecting rays intersecting at the searched aircraft location point. In this case, the searched object spatial location instantaneous (at a certain point in time) point will be placed on an imaginary “picture plane” on a line connecting the points projections generated by drones interceptors projecting rays. As far as all of the projection objects in this case are movable, all the moving trajectory projection of the searched aircraft will be displayed on the monitor. The introduction of another “picture plane”, perpendicular to the main one, will help to build an axonometric mapping not only for projections, but also for the aircraft spatial movement trajectory itself. Each point of this trajectory gives an information about the “instantaneous” coordinates of the aircraft spatial location. The method of application of kinematic projection for display of a trajectory of movement and search of coordinates of moving objects is described. In kinematic projection, all its key components, namely the object, the center of projection, the image plane and the projecting rays, are in continuous motion with certain speeds and accelerations. Kinematic projection deepens the field of practical application of descriptive geometry. This is confirmed by the example of practical application of kinematic projection presented in the article for improvement of remote control of tillage equipment in automated land treatment complexes. The main technical support for the practical application of kinematic projection are stationary radio towers or unmanned aerial vehicles (BPLA), such as drones. They are equipped with video cameras and electromagnetic radiation devices. This equipment serves as a center of kinematic projection. The projecting rays generated by the projection center will be received by a stationary command post (center). It is equipped with a radar system (radar) and modern computer equipment with appropriate software. This equipment, in this case, performs the function of a “picture plane”, which will reflect the trajectory of agricultural machinery. Actuators and controls of the movement of tillage equipment are equipped with receivers of control radio waves and means of automated control. The use of kinematic projection helps to improve the quality of tillage. This is ensured by the fact that its use is carried out automatically and eliminates possible errors of operators. Kinematic projection can also be used in military affairs to detect enemy drones in the airspace. In this case, use a kind of kinematic projection with its two centers of generation of projecting rays. This is an example of the solution of the so-called “inverse problem” of kinematic projection, which provides the ability to search for the coordinates of the motion of the projected object at a known trajectory of its motion. The main advantage of kinematic projection is the ability to identify and display an object on a computer screen not only in a flat view, but also taking into account its spatial coordinates.