Time-to-go based three-dimensional multi-missile spatio-temporal cooperative guidance law: A novel approach for maneuvering target interception.

This research presents a novel approach called 'Time-to-target-based multi-missile spatio-temporal cooperative guidance' This approach enables the simultaneous guidance of multiple missiles, allowing them to intercept a maneuvering target from different terminal intercept angles to maximize damage. The article introduces a finite-time optimal cooperative guidance technique to reduce the load on missile engines in the line-of-sight (LOS) direction. It proposes a time-varying sliding mode guidance scheme, which is parameterized by the remaining flight time, for both longitudinal and lateral LOS directions. The scheme helps prevent excessive initial acceleration in the longitudinal and lateral LOS directions while ensuring intercept angle constraints. The time-varying cooperative guidance law proposed in this study enables the simultaneous interception of a maneuvering target with different terminal intercept angles at the moment of terminal intercept. The numerical simulation results indicate that the multi-missile spatio-temporal cooperative guidance method is effective, superior, and robust. The method enables multiple missiles to achieve the minimum acceptable intercept distance at different terminal intercept angles while optimizing fuel in the LOS direction.

Three-dimensional impact-angle-constrained cooperative guidance strategy against maneuvering target.

In order to improve the multiple-missile cooperative attack capability and penetration capability, this paper investigates two three-dimensional impact-angle-constrained cooperative guidance strategies against maneuvering target for controllable thrust missiles. First, a three-dimensional nonlinear guidance model is established that does not assume small missile lead angles in the guidance process. Second, in the line-of-sight (LOS) direction of the cluster cooperative guidance strategy, the proposed guidance algorithm transforms the simultaneous attack problem into a second-order multiagent consensus problem, which effectively solves the practical problem of low guidance precision provoked by the time-to-go estimation. Then, by combining second-order sliding mode control (SMC) and nonsingular terminal SMC theory, the guidance algorithms in the normal and lateral directions to the LOS are designed, respectively, so that the multi-missile can accurately attack a maneuvering target while satisfying the impact angle constraints. Finally, by utilizing the second-order multiagent consensus tracking control in the leader-following cooperative guidance strategy, a novel leader-following time consistency algorithm is investigated to ensure that the leader and followers can attack the maneuvering target simultaneously. Moreover, the stability of the investigated guidance algorithms is proved mathematically. The effectiveness and superiority of the proposed cooperative guidance strategies are verified by numerical simulations.

Computer-Assisted 3-Dimensional-Planned Corrective Osteotomy for Symptomatic Fracture Malunion: An Ulna-Only Case Study.

We present a case of an ulna malunion managed with computer-assisted 3-dimensional planned corrective osteotomy in a patient with a history of distal radius fracture treated with open reduction internal fixation and concurrent distal ulna fracture treated conservatively. The distal ulnar diaphyseal deformity was complex and existed in multiple planes, including a clinically significant rotational deformity. Preoperative computed tomography scans were used to plan 3-dimensional guides for the osteotomy, which were subsequently printed and used during surgery. After surgery, our radiologic findings showed a high degree of accuracy and the patient demonstrated pain-free, full range of motion and returned to contact sports 4 months after surgery. This could be a reliable and precise option for complex ulnar diaphyseal malunion corrective surgery.

[Establishment of percutaneous nephrolithotomy pathway guided by C-arm CT].

Objective: To investigate the feasibility and advantages of establishing percutaneous nephrolithotomy pathway guided by C-arm CT. Methods: The data of 258 patients who were established a percutaneous nephrolithotomy pathway under the guidance of C-arm CT in the Department of Interventional Medicine of the First Affiliated Hospital of Zhengzhou University from January 2012 to December 2019 were retrospectively analyzed, including168 males and 90 females, and aged 19-88 (60±11) years. There were 84 cases of single stone, 174 cases of multiple stone, and 18 cases of cast stone. The stone size was 9-42 (22±6) mm. Among them, dual access was established in 18 cases, and nephrolithotomy access was established in 276 cases. The three-dimensional guiding function of C-arm CT was used to puncture the target calyces and establish the percutaneous nephrolithotomy pathway. Results: The pathway was successfully established in 258 cases at the first time, with a success rate of 93.5%; successfully established in 15 cases at the second time, with a success rate of 98.9%; and unable to establish in 3 cases, with a failure rate of 1.1%. The operation time was (7.9-32.5) min, with an average of (16±5) min. The lithotripsy time was (25-115) min, with an average of (43±8) min. The intraoperative blood lose was (45-420) ml, with an average of (75±11) ml. There were 23 cases with postoperative calculus residual (8.3%). Postoperative complications included fever in 86 cases (33.3%), which improved after symptomatic treatment. Postoperative hematuria was observed in 128 patients (49.6%) with varying degrees of gross hematuria, among which 2 patients (0.72%) were treated with arterial embolization due to excessive bleeding and ineffective conservative treatment, while the hematuria disappeared after symptomatic treatment in the rest of the patients. Conclusion: The method of establishing percutaneous nephrolithotomy pathway under the guidance of C-arm CT was simple to operate. Especially for patients without hydronephrosis, this method had a high success rate and low complications, which was worthy of clinical promotion and reference.

Giving up knowledge is almost never a good idea: an interview with Dr Evan Zahn.

The history of congenital interventional cardiology has seen numerous groundbreaking innovations typically related to the introduction of a new device or a novel treatment technique. Similarly, imaging of cardiac defects has changed dramatically over the past decades, although some of the advancements have seemed to omit the catheterisation laboratories. Rotational angiography, one of the imaging techniques for guidance of cardiac catheterisation currently referred to as "advanced", in fact was described already in 1960s.1 More recently its improved version, including three-dimensional reconstruction (3DRA), became a valuable intra-procedural imaging tool in interventional cardiology and neuroradiology.2 Dr Evan Zahn was one of the pioneers of 3DRA in the field of congenital cardiology, setting an example for many to follow. With his innovative publication and subsequent lecture at 2011 Pediatric and Adult Interventional Cardiac Symposium (PICS-AICS) on "The Emerging Use of 3-Dimensional Rotational Angiography in Congenital Heart Disease" he motivated many to explore benefits of this modality to strive for improved procedural outcomes and reduced patients' burden of cardiac catheterisation3. I was one of those to take Dr Zahn's thoughts and implement them into routine workflow.4-6 However, almost a decade after Dr Zahn shared his important work, despite tremendous efforts by teams from Utrecht, (Netherlands) and Columbus (Ohio, United States of America) to popularise 3D imaging in catheterisation laboratory during dedicated meetings, two-dimensional (2D) angiography does not seem to be threatened in many, otherwise-progressive, laboratories. During the recent 30th Japanese Pediatric Interventional Cardiology (JPIC) meeting I had the opportunity to ask Dr Zahn why giving up knowledge is almost never a good idea, what is technology's natural order of things, and why the technology has to be more than just exciting, pretty, and new.

Magnetic resonance and computed tomography imaging fusion for live guidance of percutaneous pulmonary valve implantation.

INTRODUCTION: Until recently, two-dimensional (2D) angiography was the mainstay of guidance for percutaneous pulmonary valve implantation (PPVI). Recent advances in fusion software have enabled direct fusion of pre-intervention imaging, magnetic resonance imaging (MRI) or computed tomography (CT) scans, to create a reliable three-dimensional (3D) roadmap for procedural guidance. AIM: To report initial two-center experience with direct 2D-3D image fusion for live guidance of PPVI with MRI- and CT-derived 3D roadmaps. MATERIAL AND METHODS: We performed a prospective study on PPVIs guided with the new fusion imaging platform introduced in the last quarter of 2015. RESULTS: 3D guidance with an MRI- (n = 14) or CT- (n = 8) derived roadmap was utilized during 22 catheterizations for right ventricular outflow tract balloon sizing (n = 7) or PPVI (n = 15). Successful 2D-3D registration was performed in all but 1 patient. Six (27%) patients required intra-procedural readjustment of the 3D roadmap due to distortion of the anatomy after introduction of a stiff wire. Twenty-one (95%) interventions were successful in the application of 3D imaging. Patients in the CT group received less contrast volume and had a shorter procedural time, though the differences were not statistically significant. Those in the MRI group had significantly lower weight adjusted radiation exposure. CONCLUSIONS: With intuitive segmentation and direct 2D-3D fusion of MRI or CT datasets, VesselNavigator facilitates PPVI. Our initial data show that utilization of CT-derived roadmaps may lead to less contrast exposure and shorter procedural time, whereas application of MRI datasets may lead to lower radiation exposure.