Abstract
Robotic operation is an effective way to upgrade the live-line maintenance safety, efficiency, and quality. This paper proposes an impedance control-based teleoperation system to improve the ...adaptability of live-line maintenance robot in outdoors environment. The key technology of this system is utilizing three virtual spring-damper systems to model the elastic connection between the end-effector of slave manipulator and the environment, between the end-effector of slave manipulator and the counterpart of master haptic device, and between the end-effector of master haptic device and its base, respectively. Experiment results show that, under control of our proposed teleoperation system, the slave manipulator is able to track the motion of master haptic device and the robot is able to complete a set of complex action to peel the coat off the cable.
Maintenance in transmission networks is an economical way to reduce upgrading network costs without decreasing its reliability. Hence, new studies regarding transmission expansion planning (TEP) must ...take into account the effects of maintenance in order to obtain realistic and economic expansion investment plans. This work presents a novel framework for multistage TEP, considering line maintenance, i.e. the expansion cost of the transmission system, network losses, costs of old-line replacement and maintenance, cost of newly constructed line maintenance, and cost of replaced line maintenance, are simultaneously optimised. The advantage of this approach is the fact that the lifetimes of the lines that are replaced, retained, and added to the transmission system are changing during the expansion horizon. These lifetimes have an impact on the maintenance expenses. Annual maintenance costs are also affected by the inflation rate. Hence, both the lifetime and inflation rate roles are integrated into the proposed model. The robustness and effectiveness of the model are tested on the IEEE 24-bus test system, using a particle swarm optimisation algorithm. The results show that the proposed formulation finds more economic investment plans for TEP when compared with those found using static formulations considering the maintenance available in specialised literature.
In robot-assisted live-line maintenance, bilateral teleoperation is still a popular and effective approach in assisting operators to accomplish hazards tasks. Particularly, teleoperation under ...overhead power lines attach greater expectation on safe operation and telepresence. In this article, we propose a visual-haptic bilateral teleoperation strategy, i.e., EMGP-VH , based on visual guidance, haptic constraint and mixed reality (MR) augmentation. To the best of our knowledge, electromagnetic field is first applied to serve the path planning of teleoperation in live-line maintenance. In visual guidance, EMG-potential fields are integrated into RRT* to calculate a low-energy path. At the same time, real-time haptic constraint is calculated based on a tube virtual fixture. MR augmentation also works as an indispensable part in both the platform construction and visual guidance. Our proposal has been extensively compared using seven objective performances and three subjective questionnaires both in simulation and real-world experiment with five different scenes and two approaches state-of-the-art, respectively. Functionality of EMGP-RRT* and effectiveness of haptic constraint are further analyzed. Results show that EMGP-RRT* has significant improvements both in searching efficiency and safety performances; and the proposed system ( EMGP-VH ) significantly contributes to improving telepresence and ensuring safe operations during live-line maintenance, resulting in a 30% reduction in operation time and a 60% decrease in trajectory offset.
With the advent of new technologies and more modern aircraft, many of the maintenance jobs traditionally scheduled for periodic block checks can now be performed in the ‘‘line maintenance” ...environment, i.e., during layovers between scheduled flights of an aircraft. This flexibility can be exploited to reduce maintenance costs and improve fleet utilisation of an airline. In this paper we introduce and study the Line Maintenance Scheduling Problem (LMSP). The LMSP assigns jobs to available maintenance opportunities, defined by aircraft routes, and sets the starting time for each job. Its objective is to minimise the deviation from this schedule with respect to given due dates for each task, without exceeding resource capacity at the airports at any moment. We formulate the LMSP as a mixed integer programming problem, and describe and compare two solution approaches for this problem: an integrated exact solution algorithm, which solves job assignment and timetabling simultaneously, and a sequential, heuristic approach. We tested our algorithms on a set of instances inspired on data provided by an industry partner. Our experiments show the applicability of both approaches on realistic settings: the exact approach was able to find the optimal solution for all instances, in less than 10 min on average. Our analysis also shows with an example that line maintenance can be more efficient when capacity is spatially spread, even if the total capacity is reduced.
•We identify a gap in the literature regarding line mantainace sheduling in the airline industry.•We introduce and provide a MIP formulation for the aircraft Line Maintenance Scheduling Problem (LMSP).•We develop two solution approaches: an integrated exact algo-rithm (ILMSP) and a sequential heuristic (SLMSP).•We test our algorithms on a set of instances, inspired on real data provided by an industry partner.•We show the potential for applicability for both approaches, achieving optimality on every tested instance in an average execution time of ten minutes.
As part of a central line-associated bloodstream infections prevention initiative, our academic medical center formed a dedicated nursing team to assist with central line insertions and provide ...support with caring for difficult lines and dressings. During the program's first 3 years, the proportion of insertion-related central line-associated bloodstream infections occurring in areas within the team's scope declined overall by 47%.
Objective
To identify the risk factors for failure of first‐line poly (ADP‐ribose) polymerase inhibitor (PARPi) maintenance therapy in patients with advanced ovarian cancer.
Method
Patients with ...stage III‐IV epithelial ovarian cancer who received first‐line PARPi maintenance therapy were retrospectively reviewed. Clinicopathologic factors were compared between two groups—recur/progression of disease (PD) and non‐recur/PD.
Results
In total, 191 patients were included. Median follow‐up was 9.9 months, and recurrence rate was 20.9%. BRCA mutations were found in 63.4% patients. Postoperative residual tumor (60.5% vs. 37.8%), non‐high grade serous carcinoma (HGSC) (15.0% vs. 6.0%), neoadjuvant chemotherapy (NAC) (55.0% vs. 35.8%), and pre‐PARPi serum CA‐125 levels ≥23.5 U/mL (35.9% vs. 15.2%) were more frequently observed in the recur/PD group. Multivariate Cox‐regression analysis revealed pre‐PARPi serum CA‐125 levels ≥23.5 U/mL (HR, 2.17; 95%CI, 1.03–4.57; p = 0.042), non‐HGSC (3.28; 1.20–8.97; p = 0.021), NAC (2.11; 1.04–4.26; p = 0.037), and no BRCA mutation (2.23; 1.12–4.44; p = 0.023) as independent risk factors associated with poor progression‐free survival (PFS). A subgroup analysis according to BRCA mutation status showed that pre‐PARPi serum CA‐125 levels ≥26.4 U/mL were the only independent risk factor for poor PFS in women with BRCA mutations (2.75; 1.03–7.39; p = 0.044). Non‐HGSC (5.05; 1.80–14.18; p = 0.002) and NAC (3.36; 1.25–9.04; p = 0.016) were independent risk factors in women without BRCA mutations.
Conclusion
High pre‐PARPi serum CA‐125 levels, non‐HGSC histology, NAC, and no BRCA mutation might be risk factors for early failure of first‐line PARPi maintenance therapy. In women with BRCA mutations, high pre‐PARPi serum CA‐125 levels, which represent a large tumor burden before PARPi, were the only independent risk factor for poor PFS.
Maintenance plays a major role in air transport management. Airlines are looking to reduce aircraft unavailability. Optimizing maintenance is a perspective to increase the operational potential of ...aircraft and offers novel managerial implications. Maintenance tasks are traditionally organized in periodic blocks of activities. In the modern aviation, more and more maintenance jobs can be performed between two flights, which is called Line Maintenance Scheduling Problem (LMSP). The expected goal of our paper is to propose an operational schedule that can be directly executed by maintainers, i.e. assigning a start time to each elementary activity and a resource to perform it. This new problem is named Operational Aircraft Line Maintenance Scheduling Problem (OALMSP). A scheduling assistant could help airlines to reduce maintenance costs and resource management. Planners have to respect task deadlines imposed by regulations, precedence constraints between certain operations and also ensure the availability of resources in order to perform specific actions. This problem is an extension of a Resource Constrained Project Scheduling Problem (RCPSP). In this article, we propose an industrial application of an automatic aircraft line maintenance scheduler based on a Constraint Programming (CP) model. The flexibility of our approach means we can easily adapt to airline use cases without changing the properties of the model. The optimization problem is generally made up of several objectives ordered according to their importance. The objectives are respectively to plan as many tasks as possible according to their priority, then to minimize both the use of resources and the deviation time between scheduled dates and target dates of tasks. The lexicographical order enables the use of human reasoning and the management of business priorities. A constructive search strategy is designed to compute a satisfying schedule within an acceptable execution time for industry application. A practical use case based on real airline data is presented and the results are compared with those found by an industrial solver taken as a reference.
•A multi-objective optimization for Operational Aircraft Line Maintenance Scheduling.•A Constraint Programming model is proposed to schedule maintenance for a medium-size fleet over a mid-term horizon time in a few minutes.•Experiments are carried out in a maintenance use case using real input data.•Results comparison with a referential industrial solution.
Live-line maintenance is an effective means to ensure the reliability of the power system. When linemen float between the high-voltage conductors and the ground potential towers, the discharge ...characteristics of air gaps are significantly affected. In this article, simplified experiments are carried out to simulate the linemen by a floating conductor. The discharge characteristics of air gaps when the floating conductor is in different positions are studied. An experimental platform with a long air gap containing a floating conductor is used to obtain the breakdown voltage and the discharge path of air gaps under a positive switching impulse. The experimental results show that the existence of a floating electrode affects the air gap breakdown voltage and the discharge path. When the transverse displacement is 80 cm, almost all the discharge paths directly connect the high voltage electrode and plane electrode. Furthermore, the influencing factors of discharge path and breakdown voltage are analyzed, and the fitting equations of breakdown voltage and discharge path probability considering spatial position coordinates are established. Finally, the easy breakdown region considering discharge path is proposed, which provides a theoretical reference for quantitative analysis of the path of linemen entering high potential safely, and to improve the working efficiency of live-line maintenance.
Replacement of lightning arrester is one of the common tasks in live-line maintenance, and peg-in-hole assembly is a very difficult operation for a robot, because there are visual inaccuracy and ...force model uncertainty in the process of assembly. This paper presents a new implementation approach fusing signals of vision detection and fuzzy force to realize the high efficiency peg-in-hole assembly by a manipulator autonomously. YOLOv3 is applied as the visual detection network for rough alignment. In the phase of precise hole-searching, we establish a two-dimensional hole-searching model by fusing signal of vision detection and fuzzy force as the condition of state transitions, and propose a new semi-supervised learning network to optimize the hole-searching routine. The performance of the approach is verified by experiments in the simulation environment and the laboratory environment.
•Dividing the peg-in-hole assembly into two phases.•Targets detected by YOLOv3 in the phase of rough alignment.•Establishing a hole-searching model by fusing the signals of vision and force.•Generative Mapping and Searching Network for optimizing the hole-searching routine.•The network is trained in the virtual environment and applied in the actual scene.
Based on a multi‐year research engagement with practice, we present a novel solution design for frontlog scheduling in aircraft line maintenance and offer theoretical insights into buffer management ...in operations. The field problem of the case airline was to improve departure reliability for long‐haul aircraft without increasing maintenance resources, and without using backup aircraft. Frontlog scheduling is the purposeful introduction of over‐maintenance as a buffer of maintenance tasks that can be opportunistically postponed. A detailed simulation of the solution introduced in the airline's operations indicates a performance frontier shift, concurrently improving departure reliability, and reducing maintenance cost. We position the novel practice in operations and maintenance management literature, arguing that the frontlog creates a new type of time buffer, available in contexts where capacity serves predictable as well as unpredictable demand. Further theoretical elaboration leads us to reconceptualize buffer management along time and capacity dimensions, reducing inventory to a special case of time buffering.
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