Siga este enlace para ver otros tipos de publicaciones sobre el tema: Placement and trajectory design.
Artículos de revistas sobre el tema "Placement and trajectory design"
Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros
Consulte los 50 mejores artículos de revistas para su investigación sobre el tema "Placement and trajectory design".
Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.
También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.
Explore artículos de revistas sobre una amplia variedad de disciplinas y organice su bibliografía correctamente.
1
Landau, Damon. "Efficient Maneuver Placement for Automated Trajectory Design". Journal of Guidance, Control, and Dynamics 41, n.º 7 (julio de 2018): 1531–41. http://dx.doi.org/10.2514/1.g003172.
Texto completo
2
Wang, Xianfeng, Huaqiao Wang y Jun Xiao. "Research on a fiber ring generating algorithm for manufacturing fiber composite rotating structures of complex geometry". Transactions of the Canadian Society for Mechanical Engineering 42, n.º 3 (1 de septiembre de 2018): 233–38. http://dx.doi.org/10.1139/tcsme-2017-0042.
Texto completoResumen
Due to its light weight and high strength, carbon fiber reinforcement resin based composite (CFRC) has been widely used in aerospace, military, and many other industries. As the manufacturing technology develops, the geometry of CFRC components has seen significant changes, such as closed surface from the traditional open surface, or quite sophisticated topologies from simple shapes. As a result, fabrication of CFRC is confronted with challenging issues related to the design of fiber placement trajectory for optimal performance. In this paper, a trajectory generating algorithm is proposed based on the centroid curve of a quasi-rotational structure, where the centroid curve is the connection of centroids of the cross-sections of the structure. After the centroid curve of the component is achieved, the cross-section profiles perpendicular to the centroid curve can be determined. An efficient number of profiles are identified to avoid any overlap among neighboring profiles along the centroid curve. In this manner, the essential data for ultimate trajectory design are eventually obtained that can precisely reflect placement angles. The present work will effectively enhance the accuracy of trajectory of fiber placement and promote the mechanical property of CFRC components.
3
Krüger, Marie T., Alexis P. R. Terrapon, Alexander Hoyningen, Chan-Hi Olaf Kim, Arno Lauber y Oliver Bozinov. "Posterior Fossa Approaches Using the Leksell Vantage Frame with a Virtual Planning Approach in a Series of 10 Patients—Feasibility, Accuracy, and Pitfalls". Brain Sciences 12, n.º 12 (24 de noviembre de 2022): 1608. http://dx.doi.org/10.3390/brainsci12121608.
Texto completoResumen
The open-face design of the Leksell Vantage frame provides many advantages. However, its more rigid, contoured design offers less flexibility than other frames. This is especially true for posterior fossa approaches. This study explores whether these limitations can be overcome by tailored frame placement using a virtual planning approach. The posterior fossa was accessed in ten patients using the Leksell Vantage frame. Frame placement was planned with the Brainlab Elements software, including a phantom-based (virtual) pre-operative planning approach. A biopsy was performed in all patients; in four, additional laser ablation surgery was performed. The accuracy of virtual frame placement was compared to actual frame placement. The posterior approach was feasible in all patients. In one case, the trajectory had to be adjusted; in another, the trajectory was switched from a right- to a left-sided approach. Both cases showed large deviations from the initially planned frame placement. A histopathological diagnosis was achieved in all patients. The new Leksell Vantage frame can be used to safely target the posterior fossa with a high diagnostic success rate and accuracy. Frame placement needs to be well-planned and executed. This can be facilitated using specific software solutions as demonstrated.
4
Wray, Steven, Ronnie Mimran, Sasidhar Vadapalli, Snehal S. Shetye, Kirk C. McGilvray y Christian M. Puttlitz. "Pedicle screw placement in the lumbar spine: effect of trajectory and screw design on acute biomechanical purchase". Journal of Neurosurgery: Spine 22, n.º 5 (mayo de 2015): 503–10. http://dx.doi.org/10.3171/2014.10.spine14205.
Texto completoResumen
OBJECT Low bone mineral density in patients undergoing lumbar spinal surgery with screws is an especially difficult challenge because poor bone quality can severely compromise the maximum achievable purchase of the screws. A relatively new technique, the cortical bone screw trajectory, utilizes a medialized trajectory in the caudocephalad direction to engage a greater amount of cortical bone within the pars interarticularis and pedicle. The objectives of this cadaveric biomechanical study were to 1) evaluate a cortical screw system and compare its mechanical performance to the traditional pedicle screw system; 2) determine differences in bone quality associated with the cortical screw trajectory versus the normal pedicle screw insertion technique; 3) determine the cortical wall breach rate with both the cortical and traditional screw trajectories; and 4) determine the performance of the traditional screw in the cortical screw trajectory. METHODS Fourteen fresh frozen human lumbar spine sections (L1–5) were used in this study (mean age 57 ± 19 years). The experimental plan involved drilling and tapping screw holes for 2 trajectories under navigation (a traditional pedicle screw and a cortical screw) in both high-and low-quality vertebrae, measuring the bone quality associated with these trajectories, placing screws in the trajectories, and evaluating the competence of the screw purchase via 2 mechanical tests (pullout and toggle). The 3 experimental variants were 1) traditional pedicle screws placed in the traditional pedicle screw trajectory, 2) traditional pedicle screws placed in the cortical screw trajectory, and 3) cortical screws placed in the cortical screw trajectory. RESULTS A statistically significant increase in bone quality was observed for the cortical trajectories with a cortical screw (42%; p < 0.001) and traditional pedicle screw (48%; p < 0.001) when compared to the traditional trajectory with a traditional pedicle screw within the high-quality bone group. These significant differences were also found in the lowquality bone cohort. All mechanical parameter comparisons (screw type and trajectory) between high-quality and lowquality samples were significant (p < 0.01), and these data were all linearly correlated (r ≥ 0.65) to bone mineral density. Not all mechanical parameters determined from pullout and toggle testing were statistically significant between the 3 screw/trajectory combinations. The incidence of cortical wall breach with the cortical or traditional pedicle screw trajectories was not significantly different. CONCLUSIONS The data demonstrated that the cortical trajectory provides denser bone that allows for utilization of smaller screws to obtain mechanical purchase that is equivalent to long pedicle screws placed in traditional pedicle screw trajectories for both normal- and low-quality bone. Overall, this biomechanical study in cadavers provides evidence that the cortical screw trajectory represents a good option to obtain fixation for the lumbar spine with low-quality bone.
5
Garell, P. Charles, Roman Mirsky, M. Daniel Noh, Christopher M. Loftus, Patrick W. Hitchon, M. Sean Grady, Ralph G. Dacey y Matthew A. Howard. "Posterior ventricular catheter burr-hole localizer". Journal of Neurosurgery 89, n.º 1 (julio de 1998): 157–60. http://dx.doi.org/10.3171/jns.1998.89.1.0157.
Texto completoResumen
✓ Proper ventricular catheter placements are associated with improved shunt performance. When placing ventricular catheters via the posterior approach, the surgeon must determine an optimum trajectory and then pass a catheter along that trajectory. The incidence of optimal posterior catheter placements is increased by using a posterior catheter guide (PCG); however, errors may still occur because of poor selection of a posterior burr-hole site. In this report an easy-to-use posterior burr-hole localizer (Localizer) is described that defines the optimum burr-hole location based on geometric relationships involving the ear and supraorbital rims. The basic design principle of the Localizer was formulated and tested by using neuronavigational imaging tools to examine normal adult ventricular anatomy in relation to surface landmarks and by reviewing imaging studies obtained in 50 adult patients with hydrocephalus. Subsequently, the Localizer was used in 28 consecutive patients scheduled to undergo shunt surgery performed by using the PCG. In all cases the catheter entered the ventricle on the first pass and postoperative imaging studies demonstrated successful placement in the ipsilateral anterior horn. There were no catheter-related complications. These early results indicate that the Localizer and PCG devices may be safe and effective when used in combination for placement of posterior ventricular catheters.
6
Choi, Woo-hyeok y Yukio Takeda. "Geometric Design and Prototyping of a (2-RRU)-URR Parallel Mechanism for Thumb Rehabilitation Therapy". Machines 9, n.º 3 (26 de febrero de 2021): 50. http://dx.doi.org/10.3390/machines9030050.
Texto completoResumen
In this paper, the geometrical design of a (2-RRU)-URR (where R and U stand for the revolute and universal joints, respectively) parallel mechanism was demonstrated for thumb rehabilitation therapy. This paper consists of two parts: the design procedure for the development of a thumb rehabilitation device and the user experiment with the prototype. Because the hand generally has a limited working area, the design of the hand attachment parts and the placement of the actuators requires careful consideration of the various factors. Along with the kinematic requirements of the device, the interaction between the mechanism and the fingers must be considered. The proposed mechanism has three actuators placed in the hand attachment. When the mechanism is attached to the hand, there is the possibility of collisions between the fingers of the user and the mechanism. Two design candidates were devised while considering the limited working area of the hand and the need to avoid collisions. Due to the dependency of the workspace on the placement of the actuators, a comparison of the workspace of the two candidate designs and the target workspace was carried out. The target workspace was determined through the use of thumb trajectory measurement data. A prototype was manufactured using 3D printed plastic and aluminum materials. To confirm the practical performance of the prototype, user experiments were conducted in which a comparison between the thumb measurement data and the controlled trajectory of each person was done. Motion in two directions, specifically, adduction–abduction and flexion–extension were performed. The results showed that the controlled trajectory of flexion–extension were closely matched to the thumb measurement trajectory. Finally, the experimental results are discussed.
7
Lang, Ke, Xiaoying Nie, Yongjian Huai y Yuanyuan Chen. "Research on object placement method based on trajectory recognition in Metaverse". Metaverse 2, n.º 2 (6 de julio de 2021): 13. http://dx.doi.org/10.54517/m.v2i2.2104.
Texto completoResumen
<p>Many studies focus on only one aspect while placing objects in virtual reality environment, such as efficiency, accuracy or interactivity. However, striking a balance between these aspects and taking into account multiple indicators is important as it is the key to improving user experience. Therefore, this paper proposes an efficient and interactive object placement method for recognizing controller trajectory in virtual reality environment. For creating user-friendly feedback, we visualize the intersection of the ray and the scene by linking the controller motion information and the ray. The trajectory is abstracted as point-clouds for matching, and the corresponding object is instantiated at the center of the trajectory. To verify the interactive performance and user satisfaction with this method, we carry out a study on user experience. The results show that both the efficiency and interaction interest are improved by applying our new method, which provides a good idea for the interactive design of virtual reality layout applications.</p>
8
Lang, Ke, Xiaoying Nie, Yongjian Huai y Yuanyuan Chen. "Research on object placement method based on trajectory recognition in Metaverse". Metaverse 2, n.º 2 (6 de julio de 2021): 13. http://dx.doi.org/10.54517/met.v2i2.2104.
Texto completoResumen
<p>Many studies focus on only one aspect while placing objects in virtual reality environment, such as efficiency, accuracy or interactivity. However, striking a balance between these aspects and taking into account multiple indicators is important as it is the key to improving user experience. Therefore, this paper proposes an efficient and interactive object placement method for recognizing controller trajectory in virtual reality environment. For creating user-friendly feedback, we visualize the intersection of the ray and the scene by linking the controller motion information and the ray. The trajectory is abstracted as point-clouds for matching, and the corresponding object is instantiated at the center of the trajectory. To verify the interactive performance and user satisfaction with this method, we carry out a study on user experience. The results show that both the efficiency and interaction interest are improved by applying our new method, which provides a good idea for the interactive design of virtual reality layout applications.</p>
9
Altalbe, Ali A., Aamir Shahzad y Muhammad Nasir Khan. "Design, Development, and Experimental Verification of a Trajectory Algorithm of a Telepresence Robot". Applied Sciences 13, n.º 7 (3 de abril de 2023): 4537. http://dx.doi.org/10.3390/app13074537.
Texto completoResumen
Background: Over the last few decades, telepresence robots (TRs) have drawn significant attention in academic and healthcare systems due to their enormous benefits, including safety improvement, remote access and economics, reduced traffic congestion, and greater mobility. COVID-19 and advancements in the military play a vital role in developing TRs. Since then, research on the advancement of robots has been attracting much attention. Methods: In critical areas, the placement and movement of humans are not safe, and researchers have started looking at the development of robots. Robot development includes many parameters to be analyzed, and trajectory planning and optimization are among them. The main objective of this study is to present a trajectory control and optimization algorithm for a cognitive architecture named auto-MERLIN. Optimization algorithms are developed for trajectory control. Results: The derived work empirically tests the solutions and provides execution details for creating the trajectory design. We develop the trajectory algorithm for the clockwise direction and another one for the clockwise and counterclockwise directions. Conclusions: Experimental results are drawn to support the proposed algorithm. Self-localization, self-driving, and right and left turn trajectories are drawn. All of the experimental results show that the designed TR works properly, with better accuracy and only a slight jitter in the orientation. The jitter is found due to the environmental factor caught by the sensors, which can be filtered easily. The results show that the proposed approach is less complex and provides better trajectory planning accuracy.
10
Wu, Chenyu, Shuo Shi, Shushi Gu, Lingyan Zhang y Xuemai Gu. "Deep Reinforcement Learning-Based Content Placement and Trajectory Design in Urban Cache-Enabled UAV Networks". Wireless Communications and Mobile Computing 2020 (14 de agosto de 2020): 1–11. http://dx.doi.org/10.1155/2020/8842694.
Texto completoResumen
Cache-enabled unmanned aerial vehicles (UAVs) have been envisioned as a promising technology for many applications in future urban wireless communication. However, to utilize UAVs properly is challenging due to limited endurance and storage capacity as well as the continuous roam of the mobile users. To meet the diversity of urban communication services, it is essential to exploit UAVs’ potential of mobility and storage resource. Toward this end, we consider an urban cache-enabled communication network where the UAVs serve mobile users with energy and cache capacity constraints. We formulate an optimization problem to maximize the sum achievable throughput in this system. To solve this problem, we propose a deep reinforcement learning-based joint content placement and trajectory design algorithm (DRL-JCT), whose progress can be divided into two stages: offline content placement stage and online user tracking stage. First, we present a link-based scheme to maximize the cache hit rate of all users’ file requirements under cache capacity constraint. The NP-hard problem is solved by approximation and convex optimization. Then, we leverage the Double Deep Q-Network (DDQN) to track mobile users online with their instantaneous two-dimensional coordinate under energy constraint. Numerical results show that our algorithm converges well after a small number of iterations. Compared with several benchmark schemes, our algorithm adapts to the dynamic conditions and provides significant performance in terms of sum achievable throughput.
11
AGUILAR-IBÁÑEZ, CARLOS, MIGUEL SUÁREZ-CASTAÑÓN y HEBERTT SIRA-RAMÍREZ. "CONTROL OF THE CHUA'S SYSTEM BASED ON A DIFFERENTIAL FLATNESS APPROACH". International Journal of Bifurcation and Chaos 14, n.º 03 (marzo de 2004): 1059–69. http://dx.doi.org/10.1142/s0218127404009594.
Texto completoResumen
In this paper, we present a flatness based control approach for the stabilization and tracking problem, for the well-known Chua chaotic circuit, that includes an additional input. We introduce two feedback controller design options for the set-point stabilization and the trajectory tracking problem: a direct pole placement approach, and Generalized Proportional Integral (GPI) approach based only on measured inputs and outputs.
12
Ahmad, Izanoordina. "Geometric sensitivity of beacon placement using airborne mobile anchors". Bulletin of Electrical Engineering and Informatics 8, n.º 4 (1 de diciembre de 2019): 1333–42. http://dx.doi.org/10.11591/eei.v8i4.1589.
Texto completoResumen
Locating fixed sensing devices with a mobile anchor is attractive for covering larger deployment areas. However, the performance sensitivity to the geometric arrangement of anchor beacon positions remains unexplored. Therefore, localization using new RSSI-based localization algorithm, which uses a volumetric probability distribution function is proposed to find the most likely position of a node by information fusion from several mobile beacon radio packets to reduce error over deterministic approaches. This paper presents the guidelines of beacon selection that leads to design the most suitable trajectory, as a trade-off between the energy costs of travelling and transmitting the beacons versus the localization accuracy.
13
Matsumaru, Takafumi, Yasutada Horiuchi, Kosuke Akai y Yuichi Ito. "Truly-Tender-Tailed Tag-Playing Robot Interface Through Friendly Amusing Mobile Function". Journal of Robotics and Mechatronics 22, n.º 3 (20 de junio de 2010): 301–7. http://dx.doi.org/10.20965/jrm.2010.p0301.
Texto completoResumen
To expand use of the mobile robot Step-On Interface (SOI), originally targeting maintenance, training, and recovery of human physical and cognitive functions, we introduce a “Truly-Tender-Tailed” (T3, pronounced tee-cube) tag-playing robot as a “Friendly Amusing Mobile” (FAM) function. Displaying a previously prepared bitmap (BMP) image and speeding up display make it easy to design button placement and other screen parameters using a painting software package. The BMP-image scope matrix simplifies step detection and recognition and the motion trajectory design editor facilitates robot behavior design.
14
Ashouri-Sanjani, Mehran, Shima Mohammadi-Moghadam, Parisa Azimi y Navid Arjmand. "Design, Fabrication, and Accuracy of a Novel Noncovering Lock-Mechanism Bilateral Patient-Specific Drill Guide Template for Nondeformed and Deformed Thoracic Spines". HSS Journal®: The Musculoskeletal Journal of Hospital for Special Surgery 17, n.º 2 (4 de marzo de 2021): 213–22. http://dx.doi.org/10.1177/1556331621996331.
Texto completoResumen
Background: Pedicle screw (PS) placement has been widely used in fusion surgeries on the thoracic spine. Achieving cost-effective yet accurate placements through nonradiation techniques remains challenging. Questions/Purposes: Novel noncovering lock-mechanism bilateral vertebra-specific drill guides for PS placement were designed/fabricated, and their accuracy for both nondeformed and deformed thoracic spines was tested. Methods: One nondeformed and 1 severe scoliosis human thoracic spine underwent computed tomographic (CT) scanning, and 2 identical proportions of each were 3-dimensional (3D) printed. Pedicle-specific optimal (no perforation) drilling trajectories were determined on the CT images based on the entry point/orientation/diameter/length of each PS. Vertebra-specific templates were designed and 3D printed, assuring minimal yet firm contacts with the vertebrae through a noncovering lock mechanism. One model of each patient was drilled using the freehand and one using the template guides (96 pedicle drillings). Postoperative CT scans from the models with the inserted PSs were obtained and superimposed on the preoperative planned models to evaluate deviations of the PSs. Results: All templates fitted their corresponding vertebra during the simulated operations. As compared with the freehand approach, PS placement deviations from their preplanned positions were significantly reduced: for the nonscoliosis model, from 2.4 to 0.9 mm for the entry point, 5.0° to 3.3° for the transverse plane angle, 7.1° to 2.2° for the sagittal plane angle, and 8.5° to 4.1° for the 3D angle, improving the success rate from 71.7% to 93.5%. Conclusions: These guides are valuable, as the accurate PS trajectory could be customized preoperatively to match the patients’ unique anatomy. In vivo studies will be required to validate this approach.
15
Janiga, Damian, Daniel Podsobiński, Paweł Wojnarowski y Jerzy Stopa. "End-Point Model for Optimization of Multilateral Well Placement in Hydrocarbon Field Developments". Energies 13, n.º 15 (31 de julio de 2020): 3926. http://dx.doi.org/10.3390/en13153926.
Texto completoResumen
Drilling cost is one of the most critical aspects in the reservoir management plan. Costs may exceed a million dollars; thus, optimal designing of the well trajectory in the reservoir and completion are essential. The implementation of a multilateral well (MLW) in reservoir management has great potential to optimize oil production. The object of this study is to develop an integrated workflow of end-point multilateral well placement optimization integrated with the reservoir simulator supported by artificial intelligence (AI) methods. The paper covers various types of MLW construction, including: horizontal, bi-, tri-, and quad-lateral wells. For quad-lateral wells, the capital expenditure is highest; nevertheless, acceleration of oil production affects the project’s NPV (net present value), indicating the type of well that is most promising to implement in the reservoir. Tri- and quad-lateral wells can operate for 12.1 and 9.8 years with a constant production rate. The decreasing hydrocarbon production rate is affected by reservoir pressure and the reservoir water production rate. Other well design patterns can accelerate water production. The well’s optimal trajectory was evaluated by the genetic algorithm (GA) and particle swarm optimization (PSO). The major difference between the GA and PSO optimization runs is visible with respect to water production and is related to the modification of one well branch trajectory in a reservoir. The proposed methodology has the advantage of easy implementation in a closed-loop optimization system coupled with numerical reservoir simulation. The paper covers the solution background, an implementation example, and the model limitations.
16
Peiyuan, Wang, Li Yong, Wang Xianfeng y Xiao Jun. "Research on Fiber Placement Trajectory Design Algorithm for the Free-Form Surface with Given Ply Orientation Information". Polymers and Polymer Composites 19, n.º 2-3 (marzo de 2011): 203–8. http://dx.doi.org/10.1177/0967391111019002-323.
Texto completo
17
Özsoy, C., A. Kural y A. Kuzucu. "Pole-Placement Position Control of a Hydraulic Robot Arm". Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 208, n.º 3 (agosto de 1994): 149–56. http://dx.doi.org/10.1243/pime_proc_1994_208_323_02.
Texto completoResumen
This paper discusses a single-input single-output discrete-time model developed to control joint position of a manipulator design for painting purposes. The input of the discrete-time model is the voltage into the control valve, and the output is the joint displacement. The model parameters are identified by using input-output data collected from the actual system. Recursive least-squares, square root, V-D factorization and variable forgetting factor methods were used for the estimation, and a good match between the model and actual system responses was obtained. The best estimation results were found by the U-D factorization algorithm according to the sum of the squared errors. Since identification results indicate a non-minimum phase system, a pole-placement self-tuning controller is designed for the purpose of joint trajectory control. The control signal computed off-line is applied to the electrohydraulic drive system and the perfect performance of the pole-placement controller is shown by the experimental studies.
18
Wang, Xinran, Hailin Ren, Anil Kumar y Pinhas Ben-Tzvi. "Design and Analysis of a Variable Inertia Spatial Robotic Tail for Dynamic Stabilization". Biomimetics 5, n.º 4 (25 de octubre de 2020): 55. http://dx.doi.org/10.3390/biomimetics5040055.
Texto completoResumen
This paper presents the design of a four degree-of-freedom (DoF) spatial tail and demonstrates the dynamic stabilization of a bipedal robotic platform through a hardware-in-loop simulation. The proposed tail design features three active revolute joints with an active prismatic joint, the latter of which provides a variable moment of inertia. Real-time experimental results validate the derived mathematical model when compared to simulated reactive moment results, both obtained while executing a pre-determined trajectory. A 4-DoF tail prototype was constructed and the tail dynamics, in terms of reactive force and moments, were validated using a 6-axis load cell. The paper also presents a case study where a zero moment point (ZMP) placement-based trajectory planner, along with a model-based controller, was developed in order for the tail to stabilize a simulated unstable biped robot. The case study also demonstrates the capability of the motion planner and controller in reducing the system’s kinetic energy during periods of instability by maintaining ZMP within the support polygon of the host biped robot. Both experimental and simulation results show an improvement in the tail-generated reactive moments for robot stabilization through the inclusion of prismatic motion while executing complex trajectories.
19
Răileanu, Silviu, Theodor Borangiu, Ionuț Lențoiu y Mihnea Constantinescu. "Optimizing Energy Consumption of Industrial Robots with Model-Based Layout Design". Sustainability 16, n.º 3 (25 de enero de 2024): 1053. http://dx.doi.org/10.3390/su16031053.
Texto completoResumen
The paper describes the development of an optimization model for the layout of an industrial robot relative to known locations of served machines and operations to be performed. Robotized material handling applications, defined by trajectories (paths, speed profiles) and final points, are considered in this research. An energy-monitoring framework set up by joint velocities provides input data that are fed to the optimization model. The physical placement of the robot base stands for the decisional variables, while the objective function is represented by the total distance covered by individual joints along established task routes transposed into energy consumption. The values of the decisional variables are restricted by trajectory constraints (waypoints on paths), joint operating values and link dimensions. Modelling technique and practical results using the Microsoft Solver optimization tool from Excel for Microsoft 365, Version 2312 are reported for SCARA-type robots. The performance of the optimization model is compared with actual measurements of consumed energy on an Adept Cobra S600 SCARA robot.
20
Rotondo, Damiano, Fatiha Nejjari y Vicenç Puig. "Robust Quasi–LPV Model Reference FTC of a Quadrotor Uav Subject to Actuator Faults". International Journal of Applied Mathematics and Computer Science 25, n.º 1 (1 de marzo de 2015): 7–22. http://dx.doi.org/10.1515/amcs-2015-0001.
Texto completoResumen
Abstract A solution for fault tolerant control (FTC) of a quadrotor unmanned aerial vehicle (UAV) is proposed. It relies on model reference-based control, where a reference model generates the desired trajectory. Depending on the type of reference model used for generating the reference trajectory, and on the assumptions about the availability and uncertainty of fault estimation, different error models are obtained. These error models are suitable for passive FTC, active FTC and hybrid FTC, the latter being able to merge the benefits of active and passive FTC while reducing their respective drawbacks. The controller is generated using results from the robust linear parameter varying (LPV) polytopic framework, where the vector of varying parameters is used to schedule between uncertain linear time invariant (LTI) systems. The design procedure relies on solving a set of linear matrix inequalities (LMIs) in order to achieve regional pole placement and H∞ norm bounding constraints. Simulation results are used to compare the different FTC strategies.
21
Pirouz, Behrouz, Stefania Anna Palermo, Seyed Navid Naghib, Domenico Mazzeo, Michele Turco y Patrizia Piro. "The Role of HVAC Design and Windows on the Indoor Airflow Pattern and ACH". Sustainability 13, n.º 14 (15 de julio de 2021): 7931. http://dx.doi.org/10.3390/su13147931.
Texto completoResumen
The purpose of heating, ventilation, and air conditioning (HVAC) systems are to create optimum thermal comfort and appropriate indoor air quality (IAQ) for occupants. Air ventilation systems can significantly affect the health risk in indoor environments, especially those by contaminated aerosols. Therefore, the main goal of the study is to analyze the indoor airflow patterns in the heating, ventilation, and air conditioning (HVAC) systems and the impact of outlets/windows. The other goal of this study is to simulate the trajectory of the aerosols from a human sneeze, investigate the impact of opening windows on the number of air changes per hour (ACH) and exhibit the role of dead zones with poor ventilation. The final goal is to show the application of computational fluid dynamics (CFD) simulation in improving the HVAC design, such as outlet locations or airflow rate, in addition to the placement of occupants. In this regard, an extensive literature review has been combined with the CFD method to analyze the indoor airflow patterns, ACH, and the role of windows. The airflow pattern analysis shows the critical impact of inflow/outflow and windows. The results show that the CFD model simulation could exhibit optimal placement and safer locations for the occupants to decrease the health risk. The results of the discrete phase simulation determined that the actual ACH could be different from the theoretical ACH as the short circuit and dead zones affect the ACH.
22
Molter, Alexandre, Otávio A. Alves da Silveira, Jun S. Ono Fonseca y Valdecir Bottega. "Simultaneous Piezoelectric Actuator and Sensor Placement Optimization and Control Design of Manipulators with Flexible Links Using SDRE Method". Mathematical Problems in Engineering 2010 (2010): 1–23. http://dx.doi.org/10.1155/2010/362437.
Texto completoResumen
This paper presents a control design for flexible manipulators using piezoelectric actuators bonded on nonprismatic links. The dynamic model of the manipulator is obtained in a closed form through the Lagrange equations. Each link is discretized using finite element modal formulation based on Euler-Bernoulli beam theory. The control uses the motor torques and piezoelectric actuators for controlling vibrations. An optimization problem with genetic algorithm (GA) is formulated for the location and size of the piezoelectric actuator and sensor on the links. The natural frequencies and mode shapes are computed by the finite element method, and the irregular beam geometry is approximated by piecewise prismatic elements. The State-Dependent Riccati Equation (SDRE) technique is used to derive a suboptimal controller for a robot control problem. A state-dependent equation is solved at each new point obtained for the variables from the problem, along the trajectory to obtain a nonlinear feedback controller. Numerical tests verify the efficiency of the proposed optimization and control design.
23
Schütz, Laura, Caroline Brendle, Javier Esteban, Sandro M. Krieg, Ulrich Eck y Nassir Navab. "Usability of Graphical Visualizations on a Tool-Mounted Interface for Spine Surgery". Journal of Imaging 7, n.º 8 (21 de agosto de 2021): 159. http://dx.doi.org/10.3390/jimaging7080159.
Texto completoResumen
Screw placement in the correct angular trajectory is one of the most intricate tasks during spinal fusion surgery. Due to the crucial role of pedicle screw placement for the outcome of the operation, spinal navigation has been introduced into the clinical routine. Despite its positive effects on the precision and safety of the surgical procedure, local separation of the navigation information and the surgical site, combined with intricate visualizations, limit the benefits of the navigation systems. Instead of a tech-driven design, a focus on usability is required in new research approaches to enable advanced and effective visualizations. This work presents a new tool-mounted interface (TMI) for pedicle screw placement. By fixing a TMI onto the surgical instrument, physical de-coupling of the anatomical target and navigation information is resolved. A total of 18 surgeons participated in a usability study comparing the TMI to the state-of-the-art visualization on an external screen. With the usage of the TMI, significant improvements in system usability (Kruskal–Wallis test p < 0.05) were achieved. A significant reduction in mental demand and overall cognitive load, measured using a NASA-TLX (p < 0.05), were observed. Moreover, a general improvement in performance was shown by means of the surgical task time (one-way ANOVA p < 0.001).
24
Mateichyk, Vasyl, Anatolii Soltus, Eduard Klimov, Nataliia Kostian, Miroslaw Smieszek y Sergii Kovbasenko. "Regularities of Changes in the Motion Resistance of Wheeled Vehicles along a Curvilinear Trajectory". Machines 11, n.º 5 (21 de mayo de 2023): 570. http://dx.doi.org/10.3390/machines11050570.
Texto completoResumen
The value of the motion resistance is one of the important characteristics that determines the technical and operational properties of the vehicle, in particular its fuel economy under operating conditions. This article summarizes the approaches to determining the rolling resistance of a wheeled vehicle in straight motion, which is a separate case from curved motion. The value of this parameter is one of the vehicle components of the motion resistance along a curved path. The regularities of changes in the motion resistance of a two-axle wheeled vehicle along a curvilinear trajectory are determined based on the determination of the motion resistance of individual wheels, which considers resistance to rectilinear motion and additional resistance along a curved path caused by the twisting and lateral displacement of the wheel disc relative to the tire patch. Analytical dependences of changes in the motion resistance along a curvilinear trajectory of two-axle vehicles with the design features of transmission, placement of tires, and their characteristics were obtained. It was found that reducing the radius of curvature of the trajectory to the minimum turning radius increases the motion resistance coefficient for the investigated vehicles by 1.68−2.04 times in relation to the rolling resistance coefficient in straight motion.
25
Kang, Bongsoo, Benny Yeung y James K. Mills. "Two-time scale controller design for a high speed planar parallel manipulator with structural flexibility". Robotica 20, n.º 5 (septiembre de 2002): 519–28. http://dx.doi.org/10.1017/s02635747020004265.
Texto completoResumen
SummaryPlanar parallel manipulators, with potential applications in high speed, high acceleration tasks such as electronic component placement, would be subject to mechanical vibration due to high inertial forces acting on the linkages and other components. To achieve high throughput capability, such motion induced vibration would have to be damped quickly, to reduce settling time of the platform position and orientation. This paper develops a two-time scale dynamic model of a three-degree-of-freedom planar parallel manipulator with structurally flexible linkages. Based on the two-time scale model, a composite controller, consisting of a computed torque controller for the slow time-scale or rigid body subsystem dynamics, and a linear-quadratic state-feedback regulator for the fast time-scale flexible dynamic subsystem, is designed. Simulation results show that the composite control scheme permits the parallel manipulator platform to follow a given desired trajectory, while damping structural vibration arising due to excitation from inertial forces.
26
Tai, Bruce L., Deborah Rooney, Francesca Stephenson, Peng-Siang Liao, Oren Sagher, Albert J. Shih y Luis E. Savastano. "Development of a 3D-printed external ventricular drain placement simulator: technical note". Journal of Neurosurgery 123, n.º 4 (octubre de 2015): 1070–76. http://dx.doi.org/10.3171/2014.12.jns141867.
Texto completoResumen
In this paper, the authors present a physical model developed to simulate accurate external ventricular drain (EVD) placement with realistic haptic and visual feedbacks to serve as a platform for complete procedural training. Insertion of an EVD via ventriculostomy is a common neurosurgical procedure used to monitor intracranial pressures and/or drain CSF. Currently, realistic training tools are scarce and mainly limited to virtual reality simulation systems. The use of 3D printing technology enables the development of realistic anatomical structures and customized design for physical simulators. In this study, the authors used the advantages of 3D printing to directly build the model geometry from stealth head CT scans and build a phantom brain mold based on 3D scans of a plastinated human brain. The resultant simulator provides realistic haptic feedback during a procedure, with visualization of catheter trajectory and fluid drainage. A multiinstitutional survey was also used to prove content validity of the simulator. With minor refinement, this simulator is expected to be a cost-effective tool for training neurosurgical residents in EVD placement.
27
Lu, En, Wei Li, Xuefeng Yang, Mengbao Fan y Yufei Liu. "Modelling and Composite Control of Single Flexible Manipulators with Piezoelectric Actuators". Shock and Vibration 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/2689178.
Texto completoResumen
The piezoelectric actuators are used to investigate the active vibration control of flexible manipulators in this paper. Based on the assumed mode method, piezoelectric coupling model, and Hamilton’s principle, the dynamic equation of the single flexible manipulator (SFM) with surface bonded actuators is established. Then, a singular perturbation model consisted of a slow subsystem and a fast subsystem is formulated and used for designing the composite controller. The slow subsystem controller is designed by fuzzy sliding mode control method, and the linear quadratic regulator (LQR) optimal control method is used to design fast subsystem controller. Furthermore, the changing trends of natural frequencies along with the changes in the position of piezoelectric actuators are obtained through the ANSYS Workbench software, by which the optimal placement of actuators is determined. Finally, numerical simulations and experiments are presented. The results demonstrate that the method of optimal placement is feasible based on the maximal natural frequency, and the composite controller presented in this paper can not only realize the trajectory tracking of the SFM and has a good result on the vibration suppression.
28
Anil Kumar CH, Ramana Kumar K.V., Paul T Joyes y Padmanabhan P. "Open Surgical Guides – A Novel Concept in Computer Guided Implantology". International Journal of Research in Pharmaceutical Sciences 11, SPL4 (25 de diciembre de 2020): 817–22. http://dx.doi.org/10.26452/ijrps.v11ispl4.4079.
Texto completoResumen
Dental implants have become so popular that more than 5 million implants are placed each year by dentists in the United States alone. However, it is generally observed that a majority of implants are placed in a less-than-ideal manner. Computer-guided surgeries are proven to have a positive impact on implant placement as well as implant treatment planning. But, despite the indisputable compensations, only a partial number of clinicians regularly practice directed transplant surgery nowadays. This article aims to examine the challenges in guided implant surgery and how a novel concept of the open guide is trying to solve these issues. The latter was used during a CT scan and was eventually converted into an actual surgical guide. However, using conventional guides is not a guarantee for proper implant placement. The reason for that was inherent in their design. Conventional guides take marvelous leeway in the drilling trajectory and no drilling depth control. Using them relies on several variables that may not be trustworthy, such as hand stability, patient immobility, and another person’s feedback on the drilling angle. Bone quality can also affect the osteotomy in situations of immediate implant placement, as the drills commonly bounce off dense bone affecting the angulation and point of entry. From a safety perspective, conventional guides do not consider the patient’s relevant anatomy.
29
Famellos, Petros, Athanasios Skevas, Asterios Koutsiadis, Christos Koutsouras y Pericles Panagiotou. "Design and Analysis of a Base Bleed Unit for the Drag Reduction of a High-Power Rocket Operating at Transonic Speeds". Aerospace 11, n.º 5 (12 de mayo de 2024): 385. http://dx.doi.org/10.3390/aerospace11050385.
Texto completoResumen
In the present study, a passive flow device is considered for drag reduction purposes through implementation in a transonic high-power rocket. The high-power rocket serves as a reference platform that, apart from the operating conditions, enforces several constraints in terms of available volume and placement locations. A step-by-step methodology is suggested, where the unit is initially broken down into an inlet and an outlet component. The flow field is investigated by means of computational modeling (CFD), where the Reynolds-averaged Navier–Stokes equations are solved coupled with turbulence models that vary depending on the design phase and the individual component. In the first design phase, the best alternative configuration is selected for each component by comparing mass flow rates and discharge coefficients. In the second design phase, each component is analyzed in greater detail based on the first phase results. Indicatively, the protruding inlet diffuser-type channel is converted into a protruding inlet nozzle-type channel to avoid choked flow phenomena, and a nozzle geometry is selected as the outlet amongst the other considered scenarios. The two components are eventually integrated into a common base bleed unit and a final assessment is made. The computational results are used to predict the performance and trajectory of the rocket through a well-established trajectory software. The overall methodology is validated against full-scale test flight data. The results show that the base bleed unit developed in the framework of this study yields a drag reduction of approximately 15% at transonic speeds without impacting the rocket mass and stability.
30
Yi, Minghui, Fei Liu, Wuxiang Zhang y Xilun Ding. "Formation Mechanism and Modeling Method of Wrinkling Defects in Variable Angle Tow Steering Fiber Placement". Aerospace 9, n.º 10 (19 de octubre de 2022): 620. http://dx.doi.org/10.3390/aerospace9100620.
Texto completoResumen
Variable angle tow steering technology is capable of manufacturing complex aviation parts with a trajectory of intricate curvature planned based on stress or profile characteristics, which greatly improves the forming efficiency, design flexibility and mechanical properties of composite structures. In view of the forming defects such as buckling and wrinkles caused by the lateral bending of fiber prepreg tow, a theoretical buckling model based on the Rayleigh Ritz method, the principle of minimum potential energy and the viscoelastic foundation is established, in which the adhesion coefficient is characterized by the degree of intimate contact to introduce process parameters. On the basis of the contact mechanics analysis, the distribution of the compaction pressure and bending stress is studied to improve the theoretical model, and the critical buckling load and the minimum radius of the tow under the normal and tangential contact conditions are determined precisely. Finally, the finite element models of compaction and variable angle steering placement are proposed, and the theoretical model and simulation model are verified by corresponding trials. It is demonstrated that defects can be effectively suppressed through optimizing process parameters.
31
Wang, Dongli, Jun Xiao, Xiangwen Ju, Mingyue Dou, Liang Li y Xianfeng Wang. "Numerical and Experiment Studies of Different Path Planning Methods on Mechanical Properties of Composite Components". Materials 14, n.º 20 (15 de octubre de 2021): 6100. http://dx.doi.org/10.3390/ma14206100.
Texto completoResumen
The purpose of this paper is to study the effects of different trajectory planning methods on the mechanical properties of components. The scope of the research includes finite element simulation calculation and experimental tests of the actual structure. The test shall be carried out in the whole load range until the failure of the structure occurs. Taking the composite conical shell as an example, a variable angle initial path generation method of the conical shell surface is proposed, and the parallel offset algorithms based on partition and the circumferential averaging are proposed to fill the surface. Then, finite element analysis is carried out for the paths that satisfy the manufacturability requirements, the analysis results show that the maximum deformation and maximum transverse as well as longitudinal stress of fiber of circumferential averaging variable angle path conical shell are reduced by 16.3%, 5.85%, and 19.76%, respectively, of that of the partition variable angle path. Finally, the strength analysis of conical shells manufactured by different trajectory design schemes is carried out through finite element analysis and actual failure tests. The finite element analysis results are in good agreement with the experimental results of the actual structure. The results show that the circumferential uniform variable angle has good quality, and it is proved that the path planning algorithm that coordinates path planning and defect suppression plays an important role in optimizing placement trajectory and improving mechanical properties of parts.
32
Benzinane, Oussama y Andreas Rauh. "Combined Observer-Based State Feedback and Optimized P/PI Control for a Robust Operation of Quadrotors". Axioms 13, n.º 5 (23 de abril de 2024): 285. http://dx.doi.org/10.3390/axioms13050285.
Texto completoResumen
This paper deals with a discrete-time observer-based state feedback control design by taking into consideration bounded parameter uncertainty, actuator faults, and stochastic noise in an inner control loop which is extended in a cascaded manner by outer PI- and P-control loops for velocity and position regulation. The aim of the corresponding subdivision of the quadrotor model is the treatment of the control design in a systematic manner. In the inner loop, linear matrix inequality techniques are employed for the placement of poles into a desired area within the complex z-plane. A robustification of the design towards noise is achieved by optimizing both control and observer gains simultaneously guaranteeing stability in a predefined bounded state domain. This procedure helps to reduce the sensitivity of the inner control loop towards changes induced by the outer one. Finally, a model-based optimization process is employed to tune the parameters of the outer P/PI controllers. To allow for the validation of accurate trajectory tracking, a comparison of the novel approach with the use of a standard extended Kalman filter-based linear-quadratic regulator synthesis is presented to demonstrate the superiority of the new design.
33
Kao, Yang-Ta, Hsiau-Wen Lin y Dai-Yi Qiu. "Implementation of Offline Consumer Behavior Tracking". International Journal of Pattern Recognition and Artificial Intelligence 35, n.º 09 (4 de mayo de 2021): 2150028. http://dx.doi.org/10.1142/s0218001421500282.
Texto completoResumen
Due to declining trading volume growth in e-commerce platforms, physical channels have attracted considerable investments from various large international companies (e.g. Alibaba, JD, Walmart, Wanda, and Wuzhou International). However, e-commerce platforms can track consumers’ behaviors (attraction to landing page design, clicks on certain products, consumer behavior trajectory tracking, clicks on advertisements, and internal link optimization of product pages), a feat unachievable in current physical channels. Consequently, this study attempted to apply the characteristics of online channels in a physical channel by using image object tracking and image detection techniques. Through this inclusion, physical channels are capable of providing consumers with more favorable experience and interaction, and brick-and-mortar store owners can obtain a more accurate understanding of consumer behaviors of store consumers. Information acquired through this system can be provided to store owners to serve as reference for merchandise placement, arrangement of display shelves, and consumer circulation path planning. This study used the technique of image processing to locate the Region of Interest and applied object tracking to get the consumer’s trajectory which successfully implemented the consumer-tracking characteristics of online platforms in a physical channel while retaining the unique experience of the physical channel. This results in a win–win scenario for businesses and consumers.
34
Levin, Ruslan Yur’evich y Valeriy Aleksandrovich Maslennikov. "The influence of the placement method of fuel dispenserson the refueling cycle of vehicles". Vestnik MGSU, n.º 5 (mayo de 2015): 103–10. http://dx.doi.org/10.22227/1997-0935.2015.5.103-110.
Texto completoResumen
Logistics of production processes at a gas station is a critical point in the system of petroleum products, on the operation of which the effectiveness and sustainability of the transport sector depends. The provision and supply of road transportation of petroleum products is one of the most urgent tasks.Technological processes of reception, storage of fuel and refuelling of motor vehicles on petrol stations needs a scientific study of their structure and organization. At the design stage of a gas station, it is necessary to consider quite a lot of different fac- tors: the configuration of the area under the gas station, the scheme of arrangement and the number of fuel dispensers, the trajectory of motion and the design of vehicles, calls to the station, distance between cars on duty, between the elements of buildings and equipment, as well as the requirements for fire, building, public, sanitary-epidemiological and state regulations. Therefore, the designer has a great opportunity for varying the parameters of the elements of the station, especially when considering the characteristics of the fueled vehicles.Typical projects at a same power station include various sizes, the seizure of land to build a station changes from planning decisions and the locations of all its technological elements. For increase of functioning efficiency of transportation systems of petroleum products in modern conditions on the basis of the design and technical innovations it is necessary to conduct special studies.Research planning decisions for a refueling station led to the conclusion that the placement of technological equipment in the refueling area has a certain impact on the length of vehicles service. Improving the layout of the refueling zone several times re- duces the loss of the components of the refueling cycle time and increase the capacity of the station.Information base describing the stages of a gas station includes parts of refueling cycle time and allows choosing the optimal variant of fuel dispensers at the fueling area. The rational layout of columns can reduce the time of customer service and increase the capacity of the object.
35
Tran, Anh-Minh Duc, Tri-Vien Vu y Quang-Dung Nguyen. "A Study on General State Model of Differential Drive Wheeled Mobile Robots". Journal of Advanced Engineering and Computation 7, n.º 3 (30 de septiembre de 2023): 174. http://dx.doi.org/10.55579/jaec.202373.417.
Texto completoResumen
This study introduces a novel approach by representing a multi-input-multi-output (MIMO) differential drive wheel mobile robot (DDWMR) using the standard state space representation for the first time. This representation facilitates the application of analysis and control system design techniques to MIMO systems. Specifically, the investigation delves into stability, controllability, observability, input-output interaction, and the relative gain array of the DDWMR model. To demonstrate the concept, the established methodology employs the conventional pole placement controller design technique to formulate a state feedback control law for trajectory tracking in the DDWMR system, utilizing both a nominal and a generalized model. The generalized model incorporates distinct parameters for the left and right motor-wheel systems, unlike the nominal model where they are assumed to be identical. Simulation results highlight that accounting for the asymmetric characteristics through the controller derived from the generalized model yields superior performance compared to the nominal model-based controller. Furthermore, the proposed model can be served as an illustrative platform for evaluating innovative MIMO control methodologies in prospective studies.
36
Pokalai, Kunakorn, David Kulikowski, Raymond L. Johnson, Manouchehr Haghighi y Dennis Cooke. "Development of a new approach for hydraulic fracturing in tight sand with pre-existing natural fractures". APPEA Journal 56, n.º 1 (2016): 225. http://dx.doi.org/10.1071/aj15017.
Texto completoResumen
Hydraulic fracturing in tight gas reservoirs has been performed in the Cooper Basin for decades in reservoirs containing high stress and pre-existing natural fractures, especially near faults. The hydraulic fracture is affected by factors such as tortuosity, high entry pressures, and the rock fabric including natural fractures. These factors cause fracture plane rotation and complexities, leading to fracture disconnection or reduced proppant placement during the treatment. In this paper, rock properties are estimated for a targeted formation using well logs to create a geomechanical model. Natural fracture and stress azimuths within the interval were interpreted from borehole image logs. The image log interpretations inferred that fissures are oriented 30–60° relative to the maximum horizontal stress. Next, diagnostic fracture injection test (DFIT) data was used with the poro-elastic stress equations to predict tectonic strains. Finally, the geomechanical model was history-matched with a planar 3D hydraulic fracturing simulator, and gave more insight into fracture propagation in an environment of pre-existing natural fractures. The natural fracture azimuths and calibrated geomechanical model are input into a framework to evaluate varying scenarios that might result based on a vertical or inclined well design. A well design is proposed based on the natural fracture orientation relative to the hydraulic fracture that minimises complexity to optimise proppant placement. In addition, further models and diagnostics are proposed to aid predicting the hydraulically induced fracture geometry, its impact on gas production, and optimising wellbore trajectory to positively interact with pre-existing natural fractures.
37
Farhad Asadi, Mahdi Khorram y S Ali A Moosavian. "Bio-inspired central pattern generator for development of Cartesian motor skills for a Quadruped Robot". World Journal of Advanced Research and Reviews 12, n.º 1 (30 de octubre de 2021): 066–85. http://dx.doi.org/10.30574/wjarr.2021.12.1.0485.
Texto completoResumen
Central Pattern Generator (CPG) plays a significant role in the generation of diverse and stable gaits patterns for animals as well as controlling their locomotion. The main contributions of this paper are the ability to develop the Cartesian motor skills and coordinating legs of the quadruped robot for gait adaption and its nominal characteristics with CPG approach. Primary, a predefined relationship between an excitation signal and essential parameters of the CPG design is programmed. Next, the coordinated oscillator's rhythmic patterns by CPG and accordingly output gait diagrams for each foot of the robot are attained. Then, these desirable features such as predictive modulation and programming the gait event sequences including leg-lifting sequences and step length, duration of the time of each footstep within a gait, coordination of swing and stance phases of all legs are calculated in terms of different spatio_temporal vectors. Furthermore, a novel Cartesian footstep basis function is designed based on the robot characteristics and consequently, the associated spatio-temporal vectors can be inserted to it, which caused to spanning the space of possible gait timing in Cartesian space. Next, Cartesian footstep planner can be computed the swing foot trajectories in workspace along movement axes and then according to these footholds and feet placement, ZMP (Zero Moment Point) reference trajectory will be calculated and obtained. Therefore, COG (Center of Gravity) trajectory can be computed by designing a preview controller on the basis of the desired ZMP trajectory. Finally, to demonstrate the effectiveness of the proposed algorithm, it is implemented on a quadruped robot on both simulation or experimental implementations and the results are compared and discussed with other references.
38
Haelermans, Carla, Timo Huijgen, Madelon Jacobs, Mark Levels, Rolf van der Velden, Lynn van Vugt y Sanne van Wetten. "Using Data to Advance Educational Research, Policy, and Practice: Design, Content, and Research Potential of the Netherlands Cohort Study on Education". European Sociological Review 36, n.º 4 (15 de julio de 2020): 643–62. http://dx.doi.org/10.1093/esr/jcaa027.
Texto completoResumen
Abstract In many countries, the quality of (large-scale quantitative) educational research is threatened by data challenges. In this article, we present an innovative data research project from the Netherlands in which many of the challenges that come forward in previous literature are addressed. The Netherlands Cohort Study on Education [in Dutch abbreviated as NCO (Nationaal Cohortonderzoek Onderwijs)] uses longitudinal register data on track placement of cohorts of pupils in primary and secondary education from Statistics Netherlands, which will be combined with school admin data on pupils’ performance and data from the major (inter)national surveys. NCO maps pupils’ pathways and performances through primary and secondary education and their trajectory into tertiary education. NCO so far covers more than 10 complete cohorts and is complemented with the newest data every year. These registers are made available at Statistics Netherlands. A major contribution of NCO is that data from school administrative systems and additional research projects are linked with administrative register data, thereby creating a unique data set that enriches not only research, but also policy and practice. This data brief elaborates on the possibilities of this database by exploring and following one of the cohorts over time.
39
Aksen, Ukte, Alim Rustem Aslan y Umit Deniz Goker. "Comprehensive Six-Degrees-of-Freedom Trajectory Design and Optimization of a Launch Vehicle with a Hybrid Last Stage Using the PSO Algorithm". Applied Sciences 14, n.º 9 (1 de mayo de 2024): 3891. http://dx.doi.org/10.3390/app14093891.
Texto completoResumen
Increased performance with reduced overall cost, and precise design and optimization of launch systems are critical to affordability. In this respect, the use of hybrid motors has increased to ease handling based on motor selection. In the current study, the launch vehicle’s performance is enhanced by incorporating a hybrid rocket motor into the last stage and optimized using particle swarm optimization to develop a six-degrees-of-freedom tool. This modification aims to increase payload placement flexibility, facilitate handling, and reduce costs. Thanks to the interactive subsystems within this research, this innovative study more comprehensively considers the launch vehicle trajectory design problem, allowing the simultaneous consideration of the effect of launch vehicle geometry along with other parameters in the system. In this context, the proposed method is applied to the Minotaur-I launch vehicle, and contributions of the detailed design and optimization are presented. Optimization results show that the percentage differences between these models for the original vehicle were observed to be 11.55% in velocity and 8.02% in altitude. However, there were differences of 10.06% and 48.8%, 15.8% and 23.2%, and 19.5% and 78.9% in altitudes and velocities when the center of gravity and moment of inertia changes were neglected, and constant aerodynamic coefficients were assumed, respectively. In all these cases, it was observed that the flight path angle was not close to zero. Moreover, the same mission was achieved by the launch vehicle with the optimized hybrid last stage and the propulsion performance was increased by about 7.64% based on the specific impulse and total impulse-over-weight ratio.
40
Brooks, Deborah, Elizabeth Beattie, Elaine Fielding, Katy Wyles y Helen Edwards. "Long-term care placement: The transitional support needs and preferences of spousal dementia caregivers". Dementia 21, n.º 3 (6 de diciembre de 2021): 794–809. http://dx.doi.org/10.1177/14713012211056461.
Texto completoResumen
Background and objectives Many spousal caregivers experience stress, depression, loneliness, guilt and grief when placing a partner with dementia into long-term care. However, there is little research about their transitional support experiences, needs and preferences. This study aimed to gain a deeper understanding of these issues from spousal caregiver and long-term care facility staff perspectives, to inform subsequent support and intervention development. Research design and methods Semi-structured interviews and small group discussions were held separately with spousal caregivers ( n = 9) and care facility staff ( n = 11). Criterion and variation sampling aimed to ensure a range of experiences and perspectives. The ‘Framework’ approach was utilised for data analysis. Interpretation was with respect to underpinning models of stress-grief process in dementia caregiving. Findings A range of informational, psychoeducational and psychosocial supports were identified to help spousal caregivers cope better with the stressors and losses experienced throughout the transition from home to long-term care. Improved education about disease progression, information relating to long-term care provision, peer support and dementia-specific grief counselling were deemed important. Opportunities for better support within care facilities were also identified. Support should be tailored to individual needs and preferences. Discussion and implications The findings suggest a supportive care framework be developed, encompassing the trajectory from assessment for and admission into long-term care to end-of-life and post-bereavement support. Spousal caregivers should have their support needs assessed by trained health or social care professionals and be offered a range of support options as appropriate.
41
Larson, Blake T., Arthur G. Erdman, Nikolaos V. Tsekos, Essa Yacoub, Panagiotis V. Tsekos y Ioannis G. Koutlas. "Design of an MRI-Compatible Robotic Stereotactic Device for Minimally Invasive Interventions in the Breast†". Journal of Biomechanical Engineering 126, n.º 4 (1 de agosto de 2004): 458–65. http://dx.doi.org/10.1115/1.1785803.
Texto completoResumen
The objective of this work was to develop a robotic device to perform biopsy and therapeutic interventions in the breast with real-time magnetic resonance imaging (MRI) guidance. The device was designed to allow for (i) stabilization of the breast by compression, (ii) definition of the interventional probe trajectory by setting the height and pitch of a probe insertion apparatus, and (iii) positioning of an interventional probe by setting the depth of insertion. The apparatus is fitted with five computer-controlled degrees of freedom for delivering an interventional procedure. The entire device is constructed of MR compatible materials, i.e. nonmagnetic and non-conductive, to eliminate artifacts and distortion of the MR images. The apparatus is remotely controlled by means of ultrasonic motors and a graphical user interface, providing real-time MR-guided planning and monitoring of the operation. Joint motion measurements found probe placement in less than 50 s and sub-millimeter repeatability of the probe tip for same-direction point-to-point movements. However, backlash in the rotation joint may incur probe tip positional errors of up to 5 mm at a distance of 40 mm from the rotation axis, which may occur for women with large breasts. The imprecision caused by this backlash becomes negligible as the probe tip nears the rotation axis. Real-time MR-guidance will allow the physician to correct this error. Compatibility of the device within the MR environment was successfully tested on a 4 Tesla MR human scanner.
42
Wu, Ai-Min, Wenhai Wang, Hui Xu, Zhong-Ke Lin, Xin-Dong Yang, Xiang-Yang Wang, Hua-Zi Xu y Yong-Long Chi. "A novel computed method to reconstruct the bilateral digital interarticular channel of atlas and its use on the anterior upper cervical screw fixation". PeerJ 4 (23 de febrero de 2016): e1737. http://dx.doi.org/10.7717/peerj.1737.
Texto completoResumen
Purpose.To investigate a novel computed method to reconstruct the bilateral digital interarticular channel of atlas and its potential use on the anterior upper cervical screw fixation.Methods.We have used the reverse engineering software (image-processing software and computer-aided design software) to create the approximate and optimal digital interarticular channel of atlas for 60 participants. Angles of channels, diameters of inscribed circles, long and short axes of ellipses were measured and recorded, and gender-specific analysis was also performed.Results.The channels provided sufficient space for one or two screws, and the parameters of channels are described. While the channels of females were smaller than that of males, no significant difference of angles between males and females were observed.Conclusion.Our study demonstrates the radiological features of approximate digital interarticular channels, optimal digital interarticular channels of atlas, and provides the reference trajectory of anterior transarticular screws and anterior occiput-to-axis screws. Additionally, we provide a protocol that can help make a pre-operative plan for accurate placement of anterior transarticular screws and anterior occiput-to-axis screws.
43
Tanksley, John A., Brian C. Werner, Evan J. Conte, David P. Lustenberger, M. Tyrrell Burrus, Stephen F. Brockmeier, F. Winston Gwathmey y Mark D. Miller. "ACL Roof Impingement Revisited: Does the Independent Femoral Drilling Technique Avoid Roof Impingement With Anteriorly Placed Tibial Tunnels?" Orthopaedic Journal of Sports Medicine 5, n.º 5 (1 de mayo de 2017): 232596711770415. http://dx.doi.org/10.1177/2325967117704152.
Texto completoResumen
Background: Anatomic femoral tunnel placement for single-bundle anterior cruciate ligament (ACL) reconstruction is now well accepted. The ideal location for the tibial tunnel has not been studied extensively, although some biomechanical and clinical studies suggest that placement of the tibial tunnel in the anterior part of the ACL tibial attachment site may be desirable. However, the concern for intercondylar roof impingement has tempered enthusiasm for anterior tibial tunnel placement. Purpose: To compare the potential for intercondylar roof impingement of ACL grafts with anteriorly positioned tibial tunnels after either transtibial (TT) or independent femoral (IF) tunnel drilling. Study Design: Controlled laboratory study. Methods: Twelve fresh-frozen cadaver knees were randomized to either a TT or IF drilling technique. Tibial guide pins were drilled in the anterior third of the native ACL tibial attachment site after debridement. All efforts were made to drill the femoral tunnel anatomically in the center of the attachment site, and the surrogate ACL graft was visualized using 3-dimensional computed tomography. Reformatting was used to evaluate for roof impingement. Tunnel dimensions, knee flexion angles, and intra-articular sagittal graft angles were also measured. The Impingement Review Index (IRI) was used to evaluate for graft impingement. Results: Two grafts (2/6, 33.3%) in the TT group impinged upon the intercondylar roof and demonstrated angular deformity (IRI type 1). No grafts in the IF group impinged, although 2 of 6 (66.7%) IF grafts touched the roof without deformation (IRI type 2). The presence or absence of impingement was not statistically significant. The mean sagittal tibial tunnel guide pin position prior to drilling was 27.6% of the sagittal diameter of the tibia (range, 22%-33.9%). However, computed tomography performed postdrilling detected substantial posterior enlargement in 2 TT specimens. A significant difference in the sagittal graft angle was noted between the 2 groups. TT grafts were more vertical, leading to angular convergence with the roof, whereas IF grafts were more horizontal and universally diverged from the roof. Conclusion: The IF technique had no specimens with roof impingement despite an anterior tibial tunnel position, likely due to a more horizontal graft trajectory and anatomic placement of the ACL femoral tunnel. Roof impingement remains a concern after TT ACL reconstruction in the setting of anterior tibial tunnel placement, although statistical significance was not found. Future clinical studies are planned to develop better recommendations for ACL tibial tunnel placement. Clinical Relevance: Graft impingement due to excessively anterior tibial tunnel placement using a TT drilling technique has been previously demonstrated; however, this may not be a concern when using an IF tunnel drilling technique. There may also be biomechanical advantages to a more anterior tibial tunnel in IF tunnel ACL reconstruction.
44
Benda, Vojtech, Jan Kubicek, Roman Madeja, David Oczka, Martin Cerny y Kamila Dostalova. "Design of Proposed Software System for Prediction of Iliosacral Screw Placement for Iliosacral Joint Injuries Based on X-ray and CT Images". Journal of Clinical Medicine 12, n.º 6 (9 de marzo de 2023): 2138. http://dx.doi.org/10.3390/jcm12062138.
Texto completoResumen
One of the crucial tasks for the planning of surgery of the iliosacral joint is placing an iliosacral screw with the goal of fixing broken parts of the pelvis. Tracking of proper screw trajectory is usually done in the preoperative phase by the acquisition of X-ray images under different angles, which guide the surgeons to perform surgery. This approach is standardly complicated due to the investigation of 2D X-ray images not showing spatial perspective. Therefore, in this pilot study, we propose complex software tools which are aimed at making a simulation model of reconstructed CT (DDR) images with a virtual iliosacral screw to guide the surgery process. This pilot study presents the testing for two clinical cases to reveal the initial performance and usability of this software in clinical conditions. This model is consequently used for a multiregional registration with reference intraoperative X-ray images to select the slide from the 3D dataset which best fits with reference X-ray. The proposed software solution utilizes input CT slices of the pelvis area to create a segmentation model of individual bone components. Consequently, a model of an iliosacral screw is inserted into this model. In the next step, we propose the software CT2DDR which makes DDR projections with the iliosacral screw. In the last step, we propose a multimodal registration procedure, which performs registration of a selected number of slices with reference X-ray, and based on the Structural Similarity Index (SSIM) and index of correlation, the procedure finds the best match of DDR with X-ray images. In this pilot study, we also provide a comparative analysis of the computational costs of the multimodal registration upon various numbers of DDR slices to show the complex software performance. The proposed complex model has versatile usage for modeling and surgery planning of the pelvis area in fractures of iliosacral joints.
45
Apuzzo, Michael L. J., John H. Neal, Cheryl H. Waters, Alan J. Appley, Stuart D. Boyd, William T. Couldwell, Vickie H. Wheelock y Leslie P. Weiner. "Utilization of Unilateral and Bilateral Stereotactically Placed Adrenomedullary-Striatal Autografts in Parkinsonian Humans: Rationale, Techniques, and Observations". Neurosurgery 26, n.º 5 (1 de mayo de 1990): 746–57. http://dx.doi.org/10.1227/00006123-199005000-00003.
Texto completoResumen
Abstract A limited clinical pilot study involving an amalgam of specialized disciplines including neurology, neuropharmacology, neuropsychology, neurosurgery, neuroanesthesia, neuroradiology, surgical pathology, neuropathology, and urological surgery was organized to clarify issues related to patient selection, optimization of grafting materials, design of a safe, effective, standardized, and reproducible surgical technique, and possible modification of clinical patterns. After initial assessment of 82 Parkinsonian patients for periods of 6 to 20 months, 10 (age, 39-68 years) were selected for unilateral or bilateral adrenomedullary autografts to the caudate nucleus with ependymal and cerebrospinal fluid contact, employing image-directed stereotactic methods. Selection was made only after clear definition of clinical pattern and optimization of medication responses. Adrenal glands were harvested by a retroperitoneal approach (mean estimated blood loss < 75 ml). Care was taken to maximize the graft content of medullary tissue. Stereotactic methods afforded standardized, reproducible, precise targeting and transit trajectory with unilateral or bilateral placement of materials within the striatum (tissue volume, 80 mm3) with access to the ventricular fluid of the frontal horn. Considerable variability in satisfactory donor medullary tissue was encountered. One patient did not undergo grafting because of unsatisfactory medullary tissue. No significant surgical complications were noted and all patients were ready for discharge 7 days after surgery. One patient who manifested no apparent clinical change died 6 weeks after bilateral grafting of unrelated causes during a lithotripsy procedure. Postmortem examination disclosed precise graft placement with a paucity of structurally preserved medullary cells. Postoperative observations, including parameters of clinical observation, medication schedules and records, patient and family commentaries, and imaging studies (computed tomograms and single photon emission computed tomograms), have been made for periods from 16 to 20 months. Sustained improvement in preexisting clinical patterns and reduction in drug requirements were observed in 4 of 8 patients. No increased benefit could be ascribed to bilateral graft placement. These observations would indicate a primary role for stereotactic methodology for cerebral graft placement, as it affords a minimally invasive but precise, safe, and reproducible surgical method. In addition, the clinical observations indicate favorable alterations in the established pattern of the disorder, which would justify further cautious exploration of alternate donor sources or refinements of biological graft site manipulations.
46
Pakzaban, Peyman. "A noninvasive laser-guided preincision localizer for spine surgery". Journal of Neurosurgery: Spine 10, n.º 2 (febrero de 2009): 145–53. http://dx.doi.org/10.3171/2008.10.spi08463.
Texto completoResumen
Object The design and utilization of a novel device for noninvasive preincision localization of the target spine segment during lumbar spine surgery is presented. Methods The device consists of 4 low-energy laser diodes, emitting planar beams, mounted around the perimeter of a ring at right angles to each other. The beams are used to align 2 radiopaque cables hanging off the sides of the patient with the target spine segment and the radiographic source and film. The performance of the device in guiding the placement of the skin incision was prospectively evaluated in 76 consecutive patients undergoing unilateral 1-level microsurgical lumbar laminotomy. Preincision lateral radiographs obtained with the device were compared with postincision localizing radiographs in all patients. Results In all patients, the location of the incision guided by the final preincision radiograph was found to precisely overlie the target segment as confirmed by a postincision radiograph, the latter obtained after exposure of the underlying laminae. In no instance was it necessary to extend the incision, modify the surgical trajectory, or repeat the postincision radiograph due to improper incision placement. The device's radiopaque cables were clearly visualized on radiography as they traversed the spine image, regardless of body mass index. The initial preincision radiograph based on the surgeon's estimate of the location of the target site localized the target segment in 58 patients (76.3%) and an adjacent segment in the remaining 18 patients (23.7%). Accuracy of the surgeon's initial estimate of the target site (but not accuracy of the device) was found to be inversely associated with body mass index (p < 0.001), thickness of the subcutaneous fat layer overlying the spine (p < 0.001), and presence of transitional lumbosacral anatomy (p = 0.03). Conclusions The localization device presented herein provides accurate noninvasive localization of the target spine segment and guides precise placement of the incision over the target segment during lumbar spine surgery.
47
Eby, Adam, Peter Early, Simon Roe, Karl Kraus, Yuan Lingnan y Jonathan Mochel. "Computed Tomographic Evaluation of Mid-thoracic Vertebral Corridors in Normal French Bulldogs". European Journal of Veterinary Medicine 2, n.º 1 (1 de febrero de 2022): 1–3. http://dx.doi.org/10.24018/ejvetmed.2022.2.1.21.
Texto completoResumen
Objectives: (1) To report internal measurements of thoracic vertebral bone morphology and (2) identify safe and clinically applicable surgical implant corridors in the T7-T9 thoracic vertebrae of French Bulldogs.
Study Design: Observational, cross‐sectional, descriptive study.
Sample Population: Seven client-owned French Bulldogs with normal thoracic vertebrae.
Methods: Computed tomographic (CT) studies of normal French Bulldogs were reviewed. Multiplanar reconstruction of the CT images was used to determine thoracic vertebral corridors. Corridor measurements included the width, length, insertion distance off midline, and angle off midline (sagittal) for each thoracic vertebra. One‐way analysis of variance was used to detect differences between groups.
Results: Measurements of vertebral corridor width (p>0.9848), length (p>0.8113), implant center (p>0.9282) and angle (p>0.3609) did not differ between each vertebra. The average vertebral corridor width was 4.5 ± 0.7 mm. The average corridor length was 17.2 ± 2.5 mm. The average corridor angle was 22.3 ± 1.9 °. The mean distance the proposed implant center was from the vertebral midline was 8.2 ± 1.1 mm. Inter-observer agreement of corridor length and implant center was good but poor for corridor angle and width.
Conclusion: Based on average corridor width and length, commercially available cortical screws or pins can be utilized for implants in this region of the thoracic spine. The angle of corridor trajectory from a dorsal approach seems most applicable for T7-T9.
Clinical Significance: Vertebral corridors can be measured using CT-MPR, and implant specifications and angles derived. Surgical guides can also be created to guide implant placement. This approach provides a simple and accurate method to guide the placement of thoracic vertebral implants.
48
I. Zi, Chollom, Tamunobereton -ari I. y Horsfall I. Opiriyabo. "DETERMINATION OF GEOMECHANICAL ROCK PROPERTY IN THE ESTIMATION OF SANDING IN FIELD “A” IN CENTRAL NIGER DELTA". Earth Science Malaysia 5, n.º 2 (29 de diciembre de 2020): 71–76. http://dx.doi.org/10.26480/esmy.02.2021.71.76.
Texto completoResumen
Well logs data from four wells were analysed for determining the petrophysical and geomechanical properties of two reservoirs in the study area. The parameters derived from these properties were used to predict the likelihood of the occurrence of sanding in the reservoirs of interest. Five sand production methods were used in predicting sanding in the reservoirs of interest. The results obtained from these sand prediction methods all showed that the reservoirs were not likely to produce sanding during drilling exploration and production. Reservoir geomechanical study has a significant role that cannot be neglected in the development of various hydrocarbon exploitation procedures, such as in the exploration and production, drilling and field development phase. The role of geomechanical properties have great impact on the drill bit selection, optimization of well trajectory placement, casing design, wellbore stability analysis, safe mud weight window (SMWW) prediction and sand production. Sand production is a serious problem widely existing in oil/gas production. The problems resulting from sand influx include abrasion of downhole tubular/casing, subsurface safety valve and surface equipment, casing/tubing buckling, failure of casing or liners from removal of surrounding formation, compaction and erosion; and loss of production caused by sand bridging in tubing and/or flow lines.
49
Amer, Muhammad Attique, Muhsan Ehsan y Muhammad Javid Akhtar. "Significance of real-time petro-physical data for an optimal remote geosteering operation in complex geological reservoirs". Geology, Geophysics and Environment 47, n.º 3 (11 de noviembre de 2021): 125–30. http://dx.doi.org/10.7494/geol.2021.47.3.125.
Texto completoResumen
In the last decade, the oil industry has transitioned from primarily drilling vertical wells to a majority of extended reach complex horizontal wells with help of geosteering techniques for better reservoir and production efficiencies. The overall objective of geosteering and well placement has helped to maximize reservoir contact by the keeping well trajectory in the pay zone with the help of quality real-time data, especially in these uncertain times of pandemic due to COVID-19. This paper illustrates the immense impact of real-time data feeds (special logging tools/images) at operation centers with the full remote expert support of multidisciplinary teams. The proper data communication mechanism is also helpful to share the information across asset teams in a timely manner to drill complex wells remotely. To achieve the desired geosteering objective, experts monitor and evaluate the real-time petro-physical data of a landing well and design the well path accordingly to stay in the pay zone/horizon. During this collaborative and integrated geosteering process, the geological and petro-physical variables like the reservoir architecture, permeability and porosity distribution, and fluid contacts are also being used to update the reservoir models in real-time, based on the latest subsurface information for better reservoir management, operational performance and timely decision making.
50
Al Yateem, Karam. "Technology Focus: Intelligent Operations (May 2023)". Journal of Petroleum Technology 75, n.º 05 (1 de mayo de 2023): 74–75. http://dx.doi.org/10.2118/0523-0074-jpt.
Texto completoResumen
The first paper selected for this Intelligent Fields Technical Focus presents the use of a unique artificial-intelligence (AI) technique from the fourth industrial revolution—dual heuristic dynamic programming—to address business opportunities associated with optimization. The background, methodology, and novelty presented by the authors are clear; however, they need to benchmark their efforts and claims of improvement with peers. The second paper demonstrates well-structured content, though the topic is detailed, with the introduction of a digital laboratory called Ibtikar toward the enablement of connecting to open-source tools with the use of AI. The collaboration in research and development, as well as addressing challenges of upstream oil and gas requirements, is commendable. The authors, however, do not address associated security concerns concerning the open-source aspect of the technology. The third paper presents a combination of technologies used to automate daily data acquisition and model updates from production databases and run a supervised machine-learning model to continuously calibrate the network model. Recommended additional reading at OnePetro: www.onepetro.org. SPE 207188 Design and Development of a Solar-Powered Pump System With Liquid-Level Sensor and Controller Using Internet of Things Technology by Chinonyelum Ejimuda, Afe Babalola University, et al. SPE 211314 Improved Field Production Planning and Cost Optimization Using Predictive Analytical Choke Performance Model and Intelligent Alarms in an Integrated Platform by Ayesha Alsaeedi, Adnoc, et al. SPE 211367 Multidisciplinary Data Integration for Artificial-Intelligence-Assisted Well Placement and Trajectory-Design Optimization Under Uncertainty by Shi Su, SLB, et al.