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Journal articles on the topic 'Reachability Parameter'
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Cassez, Franck, Peter Gjøl Jensen, and Kim Guldstrand Larsen. "Verification and Parameter Synthesis for Real-Time Programs using Refinement of Trace Abstraction*." Fundamenta Informaticae 178, no. 1-2 (2021): 31–57. http://dx.doi.org/10.3233/fi-2021-1997.
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We address the safety verification and synthesis problems for real-time systems. We introduce real-time programs that are made of instructions that can perform assignments to discrete and real-valued variables. They are general enough to capture interesting classes of timed systems such as timed automata, stopwatch automata, time(d) Petri nets and hybrid automata. We propose a semi-algorithm using refinement of trace abstractions to solve both the reachability verification problem and the parameter synthesis problem for real-time programs. All of the algorithms proposed have been implemented and we have conducted a series of experiments, comparing the performance of our new approach to state-of-the-art tools in classical reachability, robustness analysis and parameter synthesis for timed systems. We show that our new method provides solutions to problems which are unsolvable by the current state-of-the-art tools.
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Dirr, Gunther, and Michael Schönlein. "Uniform and L-ensemble reachability of parameter-dependent linear systems." Journal of Differential Equations 283 (May 2021): 216–62. http://dx.doi.org/10.1016/j.jde.2021.02.032.
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Islam, Md Ariful, Rance Cleaveland, Flavio H. Fenton, Radu Grosu, Paul L. Jones, and Scott A. Smolka. "Probabilistic reachability for multi-parameter bifurcation analysis of cardiac alternans." Theoretical Computer Science 765 (April 2019): 158–69. http://dx.doi.org/10.1016/j.tcs.2018.02.005.
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Koutris, Paraschos, and Shaleen Deep. "The Fine-Grained Complexity of CFL Reachability." Proceedings of the ACM on Programming Languages 7, POPL (2023): 1713–39. http://dx.doi.org/10.1145/3571252.
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Many problems in static program analysis can be modeled as the context-free language (CFL) reachability problem on directed labeled graphs. The CFL reachability problem can be generally solved in time O ( n 3 ), where n is the number of vertices in the graph, with some specific cases that can be solved faster. In this work, we ask the following question: given a specific CFL, what is the exact exponent in the monomial of the running time? In other words, for which cases do we have linear, quadratic or cubic algorithms, and are there problems with intermediate runtimes? This question is inspired by recent efforts to classify classic problems in terms of their exact polynomial complexity, known as fine-grained complexity. Although recent efforts have shown some conditional lower bounds (mostly for the class of combinatorial algorithms), a general picture of the fine-grained complexity landscape for CFL reachability is missing. Our main contribution is lower bound results that pinpoint the exact running time of several classes of CFLs or specific CFLs under widely believed lower bound conjectures (e.g., Boolean Matrix Multiplication, k -Clique, APSP, 3SUM). We particularly focus on the family of Dyck- k languages (which are strings with well-matched parentheses), a fundamental class of CFL reachability problems. Remarkably, we are able to show a Ω( n 2.5 ) lower bound for Dyck-2 reachability, which to the best of our knowledge is the first super-quadratic lower bound that applies to all algorithms, and shows that CFL reachability is strictly harder that Boolean Matrix Multiplication. We also present new lower bounds for the case of sparse input graphs where the number of edges m is the input parameter, a common setting in the database literature. For this setting, we show a cubic lower bound for Andersen’s Pointer Analysis which significantly strengthens prior known results.
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Wu, Di, and Xenofon Koutsoukos. "Reachability analysis of uncertain systems using bounded-parameter Markov decision processes." Artificial Intelligence 172, no. 8-9 (2008): 945–54. http://dx.doi.org/10.1016/j.artint.2007.12.002.
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Arias, Jaime, Kyungmin Bae, Carlos Olarte, Peter Csaba Ölveczky, and Laure Petrucci. "A Rewriting-logic-with-SMT-based Formal Analysis and Parameter Synthesis Framework for Parametric Time Petri Nets." Fundamenta Informaticae 192, no. 3-4 (2024): 261–312. http://dx.doi.org/10.3233/fi-242195.
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This paper presents a concrete and a symbolic rewriting logic semantics for parametric time Petri nets with inhibitor arcs (PITPNs), a flexible model of timed systems where parameters are allowed in firing bounds. We prove that our semantics is bisimilar to the “standard” semantics of PITPNs. This allows us to use the rewriting logic tool Maude, combined with SMT solving, to provide sound and complete formal analyses for PITPNs. We develop and implement a new general folding approach for symbolic reachability, so that Maude-with-SMT reachability analysis terminates whenever the parametric state-class graph of the PITPN is finite. Our work opens up the possibility of using the many formal analysis capabilities of Maude—including full LTL model checking, analysis with user-defined execution strategies, and even statistical model checking—for such nets. We illustrate this by explaining how almost all formal analysis and parameter synthesis methods supported by the state-of-the-art PITPN tool Roméo can be performed using Maude with SMT. In addition, we also support analysis and parameter synthesis from parametric initial markings, as well as full LTL model checking and analysis with user-defined execution strategies. Experiments show that our methods outperform Roméo in many cases.
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Geng, Jie, Ying Li, Hailong Guo, Huan Zhang, and Chuan Lv. "Spatial Data-Based Automatic and Quantitative Approach in Analyzing Maintenance Reachability." Applied Sciences 12, no. 24 (2022): 12804. http://dx.doi.org/10.3390/app122412804.
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Reachability, as a vital parameter in product maintainability design, exerts a tremendous influence in practical maintenance, especially in the usage stage. To decrease subjectivity in maintenance reachability analysis, this study proposes an automatic and quantitative approach based on the spatial data of the human arm to implement maintenance reachability analysis. The approach focused on two aspects, namely, accuracy and efficiency. In terms of accuracy, the presented methodology starts from the maintenance spot where the human hand is attached. An original global data sequence set was generated, including the wrist, elbow, and shoulder joints, under the constraints of kinematics, in which a data sequence represents an arm motion. Moreover, the surrounding objects are represented by their geometric data, in which each data sequence is analyzed to judge whether collision occurs between arm segments and surrounding objects. In this filtering process, the data sequence is retained if the aforementioned collision does not occur. In terms of efficiency, owing to the large number of global data sequences, the efficiency of the interval selection in collision calculation is also taken into consideration in this methodology. Unlike the traditional methods in the virtual environment, the starting point is the maintenance spot, rather than the human body. Hence, nearly all possibilities of arm postures are considered in a global perspective with little subjective involvement, which enhances the automation and objectivity in maintenance reachability analysis to a certain extent. The case study shows the usability and feasibility by a practical maintenance scene.
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Kumar, Alok, Bhagyashree Umathe, and Atul Kelkar. "A Koopman Reachability Approach for Uncertainty Analysis in Ground Vehicle Systems." Machines 12, no. 11 (2024): 753. http://dx.doi.org/10.3390/machines12110753.
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Recent progress in autonomous vehicle technology has led to the development of accurate and efficient tools for ensuring safety, which is crucial for verifying the reliability and security of vehicles. These vehicles operate under diverse conditions, necessitating the analysis of varying initial conditions and parameter values. Ensuring the safe operation of the vehicle under all these varying conditions is essential. Reachability analysis is an important tool to certify the safety and stability of the vehicle dynamics. We propose a reachability analysis approach for evaluating the response of the vehicle dynamics, specifically addressing uncertainties in the initial states and model parameters. Reachable sets illustrate all the possible states of a dynamical system that can be obtained from a given set of uncertain initial conditions. The analysis is crucial for understanding how variations in initial conditions or system parameters can lead to outcomes such as vehicle collisions or deviations from desired paths. By mapping out these reachable states, it is possible to design systems that maintain safety and reliability despite uncertainties. These insights help to ensure the stability and reliability of the vehicles, even in unpredictable conditions, by reducing accidents and optimizing performance. The nonlinearity of the model complicates the computation of reachable sets in vehicle dynamics. This paper proposes a Koopman theory-based approach that utilizes the Koopman principal eigenfunctions and the Koopman spectrum. By leveraging the Koopman principal eigenfunction, our method simplifies the computational process and offers a formal approximation for backward and forward reachable sets. First, our method effectively computes backward and forward reachable sets for a nonlinear quarter-car model with fixed parameter values. Furthermore, we applied our approach to analyze the uncertainty response for cases with uncertain parameters of the vehicle model. When compared to time-domain simulations, our proposed Koopman approach provided accurate results and also reduced the computational time by half in most cases. This demonstrates the efficiency and reliability of our proposed approach in dynamic systems uncertainty analysis using the reachable sets.
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Huu Sach, Pham. "Reachability for discrete-time dynamical set-valued systems depending on a parameter." Optimization 48, no. 1 (2000): 17–42. http://dx.doi.org/10.1080/02331930008844492.
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Qian, Moshu, Guanghua Zhong, Xinggang Yan, Heyuan Wang, and Yang Cui. "A Closed-Loop Brain Stimulation Control System Design Based on Brain-Machine Interface for Epilepsy." Complexity 2020 (April 14, 2020): 1–15. http://dx.doi.org/10.1155/2020/3136715.
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In this study, a closed-loop brain stimulation control system scheme for epilepsy seizure abatement is designed by brain-machine interface (BMI) technique. In the controller design process, the practical parametric uncertainties involving cerebral blood flow, glucose metabolism, blood oxygen level dependence, and electromagnetic disturbances in signal control are considered. An appropriate transformation is introduced to express the system in regular form for design and analysis. Then, sufficient conditions are developed such that the sliding motion is asymptotically stable. Combining Caputo fractional order definition and neural network (NN), a finite time fractional order sliding mode (FFOSM) controller is designed to guarantee reachability of the sliding mode. The stability and reachability analysis of the closed-loop tracking control system gives the guideline of parameter selection, and simulation results based on comprehensive comparisons are carried out to demonstrate the effectiveness of proposed approach.
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Levy, Orin, and Yishay Mansour. "Optimism in Face of a Context:Regret Guarantees for Stochastic Contextual MDP." Proceedings of the AAAI Conference on Artificial Intelligence 37, no. 7 (2023): 8510–17. http://dx.doi.org/10.1609/aaai.v37i7.26025.
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We present regret minimization algorithms for stochastic contextual MDPs under minimum reachability assumption, using an access to an offline least square regression oracle. We analyze three different settings: where the dynamics is known, where the dynamics is unknown but independent of the context and the most challenging setting where the dynamics is unknown and context-dependent. For the latter, our algorithm obtains regret bound (up to poly-logarithmic factors) of order (H+1/pₘᵢₙ)H|S|³ᐟ²(|A|Tlog(max{|?|,|?|} /?))¹ᐟ² with probability 1−?, where ? and ? are finite and realizable function classes used to approximate the dynamics and rewards respectively, pₘᵢₙ is the minimum reachability parameter, S is the set of states, A the set of actions, H the horizon, and T the number of episodes. To our knowledge, our approach is the first optimistic approach applied to contextual MDPs with general function approximation (i.e., without additional knowledge regarding the function class, such as it being linear and etc.). We present a lower bound of ?((TH|S||A|ln|?| /ln|A| )¹ᐟ² ), on the expected regret which holds even in the case of known dynamics. Lastly, we discuss an extension of our results to CMDPs without minimum reachability, that obtains order of T³ᐟ⁴ regret.
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Thomas, J., D. Dumur, S. Olaru, and J. Buisson. "Reachability and Robust Control of PWA Systems with Parameter Variations and Bounded Disturbance." IFAC Proceedings Volumes 41, no. 2 (2008): 10190–95. http://dx.doi.org/10.3182/20080706-5-kr-1001.01724.
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Zhang, Yedi, Lei Huang, Pengfei Gao, Fu Song, Jun Sun, and Jin Song Dong. "Verification of Bit-Flip Attacks against Quantized Neural Networks." Proceedings of the ACM on Programming Languages 9, OOPSLA1 (2025): 984–1014. https://doi.org/10.1145/3720471.
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In the rapidly evolving landscape of neural network security, the resilience of neural networks against bit-flip attacks (i.e., an attacker maliciously flips an extremely small amount of bits within its parameter storage memory system to induce harmful behavior), has emerged as a relevant area of research. Existing studies suggest that quantization may serve as a viable defense against such attacks. Recognizing the documented susceptibility of real-valued neural networks to such attacks and the comparative robustness of quantized neural networks (QNNs), in this work, we introduce BFAVerifier, the first verification framework designed to formally verify the absence of bit-flip attacks against QNNs or to identify all vulnerable parameters in a sound and rigorous manner. BFAVerifier comprises two integral components: an abstraction-based method and an MILP-based method. Specifically, we first conduct a reachability analysis with respect to symbolic parameters that represent the potential bit-flip attacks, based on a novel abstract domain with a sound guarantee. If the reachability analysis fails to prove the resilience of such attacks, then we encode this verification problem into an equivalent MILP problem which can be solved by off-the-shelf solvers. Therefore, BFAVerifier is sound, complete, and reasonably efficient. We conduct extensive experiments, which demonstrate its effectiveness and efficiency across various activation functions, quantization bit-widths, and adversary capabilities.
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Lakatos, Eszter, and Michael P. H. Stumpf. "Control mechanisms for stochastic biochemical systems via computation of reachable sets." Royal Society Open Science 4, no. 8 (2017): 160790. http://dx.doi.org/10.1098/rsos.160790.
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Controlling the behaviour of cells by rationally guiding molecular processes is an overarching aim of much of synthetic biology. Molecular processes, however, are notoriously noisy and frequently nonlinear. We present an approach to studying the impact of control measures on motifs of molecular interactions that addresses the problems faced in many biological systems: stochasticity, parameter uncertainty and nonlinearity. We show that our reachability analysis formalism can describe the potential behaviour of biological (naturally evolved as well as engineered) systems, and provides a set of bounds on their dynamics at the level of population statistics: for example, we can obtain the possible ranges of means and variances of mRNA and protein expression levels, even in the presence of uncertainty about model parameters.
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Ayhan, Bulent, Chiman Kwan, Bence Budavari, Jude Larkin, and David Gribben. "Preflight Contingency Planning Approach for Fixed Wing UAVs with Engine Failure in the Presence of Winds." Sensors 19, no. 2 (2019): 227. http://dx.doi.org/10.3390/s19020227.
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Preflight contingency planning that utilizes wind forecast in path planning can be highly beneficial to unmanned aerial vehicles (UAV) operators in preventing a possible mishap of the UAV. This especially becomes more important if the UAV has an engine failure resulting in the loss of all its thrust. Wind becomes a significant factor in determining reachability of the emergency landing site in a contingency like this. The preflight contingency plans can guide the UAV operators about how to glide the aircraft to the designated emergency landing site to make a safe landing. The need for a preflight or in-flight contingency plan is even more obvious in the case of a communication loss between the UAV operator and UAV since the UAV will then need to make the forced landing autonomously without the operator. In this paper, we introduce a preflight contingency planning approach that automates the forced landing path generation process for UAVs with engine failure. The contingency path generation aims true reachability to the emergency landing site by including the final approach part of the path in forecast wind conditions. In the contingency path generation, no-fly zones that could be in the area are accounted for and the contingency flight paths do not pass through them. If no plans can be found that fulfill reachability in the presence of no-fly zones, only then, as a last resort, the no-fly zone avoidance rule is relaxed. The contingency path generation utilizes hourly forecast wind data from National Oceanic and Atmospheric Administration for the geographical area of interest and time of the flight. Different from past works, we use trochoidal paths instead of Dubins curves and incorporate wind as a parameter in the contingency path design.
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Gao, Lijun, and Yuqiang Wu. "H∞Control for Stochastic Systems with Markovian Switching and Time-Varying Delay via Sliding Mode Design." Mathematical Problems in Engineering 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/898172.
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This paper addresses the problem ofH∞control for a class of uncertain stochastic systems with Markovian switching and time-varying delays. The system under consideration is subject to time-varying norm-bounded parameter uncertainties and an unknown nonlinear function in the state. An integral sliding surface corresponding to every mode is first constructed, and the given sliding mode controller concerning the transition rates of modes can deal with the effect of Markovian switching. The synthesized sliding mode control law ensures the reachability of the sliding surface for corresponding subsystems and the global stochastic stability of the sliding mode dynamics. A simulation example is presented to illustrate the proposed method.
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Badings, Thom, Licio Romao, Alessandro Abate, and Nils Jansen. "Probabilities Are Not Enough: Formal Controller Synthesis for Stochastic Dynamical Models with Epistemic Uncertainty." Proceedings of the AAAI Conference on Artificial Intelligence 37, no. 12 (2023): 14701–10. http://dx.doi.org/10.1609/aaai.v37i12.26718.
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Capturing uncertainty in models of complex dynamical systems is crucial to designing safe controllers. Stochastic noise causes aleatoric uncertainty, whereas imprecise knowledge of model parameters leads to epistemic uncertainty. Several approaches use formal abstractions to synthesize policies that satisfy temporal specifications related to safety and reachability. However, the underlying models exclusively capture aleatoric but not epistemic uncertainty, and thus require that model parameters are known precisely. Our contribution to overcoming this restriction is a novel abstraction-based controller synthesis method for continuous-state models with stochastic noise and uncertain parameters. By sampling techniques and robust analysis, we capture both aleatoric and epistemic uncertainty, with a user-specified confidence level, in the transition probability intervals of a so-called interval Markov decision process (iMDP). We synthesize an optimal policy on this iMDP, which translates (with the specified confidence level) to a feedback controller for the continuous model with the same performance guarantees. Our experimental benchmarks confirm that accounting for epistemic uncertainty leads to controllers that are more robust against variations in parameter values.
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Guo, Wanjin, Ruifeng Li, Yaguang Zhu, Tong Yang, Rui Qin, and Zhixin Hu. "A Robotic Deburring Methodology for Tool Path Planning and Process Parameter Control of a Five-Degree-of-Freedom Robot Manipulator." Applied Sciences 9, no. 10 (2019): 2033. http://dx.doi.org/10.3390/app9102033.
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Industrial robotics is a continuously developing domain, as industrial robots have demonstrated to possess benefits with regard to robotic automation solutions in the industrial automation field. In this article, a new robotic deburring methodology for tool path planning and process parameter control is presented for a newly developed five-degree-of-freedom hybrid robot manipulator. A hybrid robot manipulator with dexterous manipulation and two experimental platforms of robot manipulators are presented. A robotic deburring tool path planning method is proposed for the robotic deburring tool position and orientation planning and the robotic layered deburring planning. Also, a robotic deburring process parameter control method is proposed based on fuzzy control. Furthermore, a dexterous manipulation verification experiment is conducted to demonstrate the dexterous manipulation and the orientation reachability of the robot manipulator. Additionally, two robotic deburring experiments are conducted to verify the effectiveness of the two proposed methods and demonstrate the highly efficient and dexterous manipulation and deburring capacity of the robot manipulator.
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Zhang, Xizheng, Yaonan Wang, and Xiaofang Yuan. "H∞ Robust T-S Fuzzy Design for Uncertain Nonlinear Systems with State Delays Based on Sliding Mode Control." International Journal of Computers Communications & Control 5, no. 4 (2010): 592. http://dx.doi.org/10.15837/ijccc.2010.4.2518.
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This paper presents the fuzzy design of sliding mode control (SMC) for nonlinear systems with state delay, which can be represented by a Takagi-Sugeno (TS) model with uncertainties. There exist the parameter uncertainties in both the state and input matrices, as well as the unmatched external disturbance. The key feature of this work is the integration of SMC method with H∞ technique such that the robust asymptotically stability with a prescribed disturbance attenuation level γ can be achieved. A sufficient condition for the existence of the desired SMC is obtained by solving a set of linear matrix inequalities (LMIs). The reachability of the specified switching surface is proven. Simulation results show the validity of the proposed method.
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Tang, Chunhua, Han Wang, Zhiwen Wang, Xiangkun Zeng, Huaran Yan, and Yingjie Xiao. "An improved OPTICS clustering algorithm for discovering clusters with uneven densities." Intelligent Data Analysis 25, no. 6 (2021): 1453–71. http://dx.doi.org/10.3233/ida-205497.
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Most density-based clustering algorithms have the problems of difficult parameter setting, high time complexity, poor noise recognition, and weak clustering for datasets with uneven density. To solve these problems, this paper proposes FOP-OPTICS algorithm (Finding of the Ordering Peaks Based on OPTICS), which is a substantial improvement of OPTICS (Ordering Points To Identify the Clustering Structure). The proposed algorithm finds the demarcation point (DP) from the Augmented Cluster-Ordering generated by OPTICS and uses the reachability-distance of DP as the radius of neighborhood eps of its corresponding cluster. It overcomes the weakness of most algorithms in clustering datasets with uneven densities. By computing the distance of the k-nearest neighbor of each point, it reduces the time complexity of OPTICS; by calculating density-mutation points within the clusters, it can efficiently recognize noise. The experimental results show that FOP-OPTICS has the lowest time complexity, and outperforms other algorithms in parameter setting and noise recognition.
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Lin, Conghao. "Kinematic Analysis, Workspace Optimization, and Structural Validation of the XB4 Robotic Arm for Intelligent Manufacturing." Applied and Computational Engineering 142, no. 1 (2025): 188–99. https://doi.org/10.54254/2755-2721/2025.kl22303.
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Advancements in automation have led to widespread adoption of robotic arms in industrial, medical, and service sectors, accelerating intelligent transformation. This study investigates the XB4 robotic arm by analyzing its kinematics, workspace reachability, and structural reliability using the modified Denavit-Hartenberg (D-H) parameter method, Monte Carlo simulations, and finite element analysis. A refined link coordinate system is established, and MATLAB simulations are conducted to evaluate workspace distribution. Additionally, structural analysis verifies the strength and rigidity of the robotic arms base. Results demonstrate that the XB4 robotic arm exhibits high kinematic accuracy, an optimized workspace, and robust structural integrity, making it well-suited for automation in complex industrial environments. The findings provide theoretical guidance for robotic arm design and optimization, facilitating advancements in intelligent manufacturing.
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Tran, Anh-Tuan, Van Van Huynh, and Thinh Lam-The Tran. "Apply Honey Barger Algorithm to double integral sliding mode observer for stable load frequency in multi-area power system." Journal of Advanced Engineering and Computation 8, no. 3 (2024): 187. http://dx.doi.org/10.55579/jaec.202483.465.
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A randomness of load demand and plant uncertainties causes frequency deviation in linked power plants. Based on the double-integral sliding mode observer (DISMO) integrated Honey Badger algorithm (HBA), a novel LFC for a multi-area power plant (MAPP) is introduced in this article. The main aim is to minimize frequency offset, finite time, and aggregate instability of controllable loads subject to the balance of the power on the MAPP. Firstly, the suggested observer is developed to ensure an exact estimation of the actual signal for the controller input signal. Secondly, a double-integral sliding surface (DISS) is introduced based on estimated signals the designed observer gains. Then, a new SMC rule is designed to ensure finite time reachability and eliminate the chattering and oscillating troubles. Thirdly, in this regard, the proposed sliding surface is designed with four selected parameters. Regarding this, to maximize the ability of the suggested SMCer, the optimized controller parameters are determined by HBA. The robustness of the suggested scheme is examined by various case studies on the LFC models in a single-area power plant (SAPP) and MAPP under different load disturbances and parameter uncertainties.
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Ren, Yan, Zhenghua Liu, Xiaodong Liu, and Yu Zhang. "A Chattering Free Discrete-Time Global Sliding Mode Controller for Optoelectronic Tracking System." Mathematical Problems in Engineering 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/951492.
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Aiming at the uncertainties including parameter variations and external disturbances in optoelectronic tracking system, a discrete-time global sliding mode controller (DGSMC) is proposed. By the design of nonlinear switching function, the initial state of control system is set on the switching surface. An adaptive discrete-time reaching law is introduced to suppress the high-frequency chattering at control input, and a linear extrapolation method is employed to estimate the unknown uncertainties and commands. The global reachability for sliding mode and the chattering-free property are proven by means of mathematical derivation. Numerical simulation presents that the proposed DGSMC scheme not only ensures strong robustness against system uncertainties and small tracking error, but also suppresses the high-frequency chattering at control input effectively, compared with the SMC scheme using conventional discrete-time reaching law.
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He, Zhaolan, Xue Wang, Zongwei Gao, and Jingjie Bai. "Sliding Mode Control Based on Observer for a Class of State-Delayed Switched Systems with Uncertain Perturbation." Mathematical Problems in Engineering 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/614878.
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This paper is concerned with a state observer-based sliding mode control design methodology for a class of continuous-time state-delayed switched systems with unmeasurable states and nonlinear uncertainties. The advantages of the proposed scheme mainly lie in which it eliminates the need for state variables to be full accessible and parameter uncertainties to be satisfied with the matching condition. Firstly, a state observer is constructed, and a sliding surface is designed. By matrix transformation techniques, combined with Lyapunov function and sliding surface function, a sufficient condition is given to ensure asymptotic stability of the overall closed-loop systems composed of the observer dynamics and the estimation error dynamics. Then, reachability of sliding surface is investigated. At last, an illustrative numerical example is presented to prove feasibility of the proposed approaches.
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Peng, Chuanlang, Qingchun Feng, Zhengwei Guo, et al. "Structural Parameter Optimization of a Tomato Robotic Harvesting Arm: Considering Collision-Free Operation Requirements." Plants 13, no. 22 (2024): 3211. http://dx.doi.org/10.3390/plants13223211.
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The current harvesting arms used in harvesting robots are developed based on standard products. Due to design constraints, they are unable to effectively avoid obstacles while harvesting tomatoes in tight spaces. To enhance the robot’s capability in obstacle-avoidance picking of tomato bunches with various postures, this study proposes a geometric parameter optimization method for a 7 degree of freedom (DOF) robotic arm. This method ensures that the robot can reach a predetermined workspace with a more compact arm configuration. The optimal picking posture for the end-effector is determined by analyzing the spatial distribution of tomato bunches, the main stem position, and peduncle posture, enabling a quantitative description of the obstacle-avoidance workspace. The denavit–hartenberg (D-H) model of the harvesting arm and the expected collision-free workspace are set as constraints. The compactness of the arm and the accessibility of the harvesting space serve as the optimization objectives. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) multi-objective genetic algorithm is employed to optimize the arm length, and the results were validated through a virtual experiment using workspace traversal. The results indicate that the optimized structure of the tomato harvesting arm is compact, with a reachability of 92.88% in the workspace, based on the collision-free harvesting criteria. This study offers a reference for structural parameter optimization of robotic arms specialized in fruit and vegetable harvesting.
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Saad, Wajdi, Anis Sellami, and Germain Garcia. "Robust stabilization of one-sided Lipschitz nonlinear systems via adaptive sliding mode control." Journal of Vibration and Control 26, no. 7-8 (2019): 399–412. http://dx.doi.org/10.1177/1077546319889413.
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In this paper, the problem of adaptive sliding mode control for varied one-sided Lipschitz nonlinear systems with uncertainties is investigated. In contrast to existing sliding mode control design methods, the considered models, in the current study, are affected by nonlinear control inputs, one-sided Lipschitz nonlinearities, unknown disturbances and parameter uncertainties. At first, to design the sliding surface, a specific switching function is defined. The corresponding nonlinear equivalent control is extracted and the resulting sliding mode dynamic is given. Novel synthesis conditions of asymptotic stability are derived in terms of linear matrix inequalities. Thereafter, to ensure the reachability of system states and the occurrence of the sliding mode, the sliding mode controller is designed. Any knowledge of the upper bound on the perturbation is not required and an adaptation law is proposed. At last, two illustrative examples are introduced.
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Rauh, Andreas, Marco Kletting, and Eberhard P. Hofer. "Interval techniques for enclosures of regions of reachability and controllability and for guaranteed state and parameter estimation of dynamical systems." PAMM 7, no. 1 (2007): 1023009–10. http://dx.doi.org/10.1002/pamm.200700788.
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Paul, Mridul, and Ajanta Das. "Service Level Agreements for Smart Healthcare in Cloud." International Journal of Grid and High Performance Computing 9, no. 4 (2017): 57–70. http://dx.doi.org/10.4018/ijghpc.2017100104.
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With the advancement of Cloud computing, the adoption of cloud service in various industries is fast increasing. This is evident in the healthcare domain where the adoption is on the rise recently. However, the research contribution in this domain has been limited to certain functions. While cloud can increase availability, reachability of services, it is critical to design the healthcare service before provisioning. Besides, it is important to formulate Service Level Agreements (SLAs) to ensure that consumers can get guaranteed service from the service provider. The objective of this paper is to design the cloud based smart services for patient diagnostics. This research specifically defines service architecture for patients, physicians and diagnostic centers. In order to measure the proposed services, metrics of each SLA parameter is described with its functional and non-functional requirements. This paper also explains a case study implementation of a basic patient service using Google App Engine.
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Bashkin, E. B., P. A. Baskakov, R. V. Ershova, and A. Yu Plotnikov. "General issues of artificial general intelligence." Journal of Digital Economy Research 1, no. 3 (2023): 79–101. http://dx.doi.org/10.24833/14511791-2023-3-79-101.
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Online education industry has been growing strongly in recent years. The market for educational platforms that provides access to online learning is growing every year. With the increasing growth of online course enrollment, the interest of researchers to study the effectiveness of online learning is increasing. This paper summarizes the results of a study of online courses on the Stepik educational platform. The courses selected for analysis were divided into three groups according to the parameter of learners’ “reachability” to the end of training. The process of course completion by 36226 online course participants was analyzed. The main purpose of the study was to identify the factors affecting the yield parameter. The data obtained in the study suggest that the design of online courses does not affect the learning effectiveness and the yield parameter. We attribute such results to the fact that “instructional presence” and “social presence” are almost completely absent in the online learning process, as interaction with the instructor and other learners is minimized. “Cognitive presence” formed through interaction with the educational material is insufficient to form the level of engagement necessary to complete the learning. The study also identified the main points of “falling out” of learners from the educational process and formulated the strategies that learners resort to. The obtained data indicate that the parameter of profitability and effectiveness of online learning is most influenced by the qualitative (psychological) criteria of learners. The conclusion of this article suggests the main directions for further research, which can contribute to obtaining more complete data on the factors affecting the effectiveness of online learning.
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Barragan-Vite, Irving, Joselito Medina-Marin, Norberto Hernandez-Romero, and Gustavo Erick Anaya-Fuentes. "A Petri Net-Based Algorithm for Solving the One-Dimensional Cutting Stock Problem." Applied Sciences 14, no. 18 (2024): 8172. http://dx.doi.org/10.3390/app14188172.
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This paper addresses the one-dimensional cutting stock problem, focusing on minimizing total stock usage. Most procedures that deal with this problem reside on linear programming methods, heuristics, metaheuristics, and hybridizations. These methods face drawbacks like handling only low-complexity instances or requiring extensive parameter tuning. To address these limitations we develop a Petri-net model to construct cutting patterns. Using the filtered beam search algorithm, the reachability tree of the Petri net is constructed level by level from its root node to find the best solution, pruning the nodes that worsen the solution as the search progresses through the tree. Our algorithm is compared with the Least Lost Algorithm and the Generate and Solve algorithm over five datasets of instances. These algorithms share some characteristics with ours and have proven to be effective and efficient. Experimental results demonstrate that our algorithm effectively finds optimal and near-optimalsolutions for both low and high-complexity instances. These findings confirm that Petri nets are suitable for modeling and solving the one-dimensional cutting stock problem.
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Chini, Peter, Roland Meyer, and Prakash Saivasan. "Fine-Grained Complexity of Safety Verification." Journal of Automated Reasoning 64, no. 7 (2020): 1419–44. http://dx.doi.org/10.1007/s10817-020-09572-x.
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Abstract We study the fine-grained complexity of Leader Contributor Reachability ($${\textsf {LCR}} $$ LCR ) and Bounded-Stage Reachability ($${\textsf {BSR}} $$ BSR ), two variants of the safety verification problem for shared memory concurrent programs. For both problems, the memory is a single variable over a finite data domain. Our contributions are new verification algorithms and lower bounds. The latter are based on the Exponential Time Hypothesis ($${\textsf {ETH}} $$ ETH ), the problem $${\textsf {Set~Cover}} $$ Set Cover , and cross-compositions. $${\textsf {LCR}} $$ LCR is the question whether a designated leader thread can reach an unsafe state when interacting with a certain number of equal contributor threads. We suggest two parameterizations: (1) By the size of the data domain $${\texttt {D}}$$ D and the size of the leader $${\texttt {L}}$$ L , and (2) by the size of the contributors $${\texttt {C}}$$ C . We present algorithms for both cases. The key techniques are compact witnesses and dynamic programming. The algorithms run in $${\mathcal {O}}^*(({\texttt {L}}\cdot ({\texttt {D}}+1))^{{\texttt {L}}\cdot {\texttt {D}}} \cdot {\texttt {D}}^{{\texttt {D}}})$$ O ∗ ( ( L · ( D + 1 ) ) L · D · D D ) and $${\mathcal {O}}^*(2^{{\texttt {C}}})$$ O ∗ ( 2 C ) time, showing that both parameterizations are fixed-parameter tractable. We complement the upper bounds by (matching) lower bounds based on $${\textsf {ETH}} $$ ETH and $${\textsf {Set~Cover}} $$ Set Cover . Moreover, we prove the absence of polynomial kernels. For $${\textsf {BSR}} $$ BSR , we consider programs involving $${\texttt {t}}$$ t different threads. We restrict the analysis to computations where the write permission changes $${\texttt {s}}$$ s times between the threads. $${\textsf {BSR}} $$ BSR asks whether a given configuration is reachable via such an $${\texttt {s}}$$ s -stage computation. When parameterized by $${\texttt {P}}$$ P , the maximum size of a thread, and $${\texttt {t}}$$ t , the interesting observation is that the problem has a large number of difficult instances. Formally, we show that there is no polynomial kernel, no compression algorithm that reduces the size of the data domain $${\texttt {D}}$$ D or the number of stages $${\texttt {s}}$$ s to a polynomial dependence on $${\texttt {P}}$$ P and $${\texttt {t}}$$ t . This indicates that symbolic methods may be harder to find for this problem.
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Lisac, Melanie, Lutz Reimers, Klaus-Dirk Henke, and Sophia Schlette. "Access and choice – competition under the roof of solidarity in German health care: an analysis of health policy reforms since 2004." Health Economics, Policy and Law 5, no. 1 (2010): 31–52. http://dx.doi.org/10.1017/s1744133109990144.
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AbstractThis paper analyses the influence of recent German health care reforms, the Statutory Health Insurance Modernization Act 2004 and the Statutory Health Insurance Competition Strengthening Act 2007, on different dimensions of access and choice. More specifically, we look at and discuss the effects of these policies on the availability, reachability and affordability of health care as well as on their impact on consumers’ choice of insurers and providers. Generally, patients in Germany enjoy a high degree of free access and a lot of freedom to choose, partly leading to over- and misuse of health services. Concerning choice of insurers, one result of our analysis is that in the statutory health insurance system, the introduction of a greater variety of benefit packages will develop into an additional parameter of choice. In contrast to that, insurees more and more accept certain restrictions of choice and direct access to providers by enrolling into new forms of care (such as gatekeeping-, disease management- and integrated care programmes). However, they might benefit from better quality of care and more options for products and services that best fit their needs.
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Nazeer, Irfan, Tabasam Rashid, and Muhammad Tanveer Hussain. "Cyclic connectivity index of fuzzy incidence graphs with applications in the highway system of different cities to minimize road accidents and in a network of different computers." PLOS ONE 16, no. 9 (2021): e0257642. http://dx.doi.org/10.1371/journal.pone.0257642.
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A parameter is a numerical factor whose values help us to identify a system. Connectivity parameters are essential in the analysis of connectivity of various kinds of networks. In graphs, the strength of a cycle is always one. But, in a fuzzy incidence graph (FIG), the strengths of cycles may vary even for a given pair of vertices. Cyclic reachability is an attribute that decides the overall connectedness of any network. In graph the cycle connectivity (CC) from vertex a to vertex b and from vertex b to vertex a is always one. In fuzzy graph (FG) the CC from vertex a to vertex b and from vertex b to vertex a is always same. But if someone is interested in finding CC from vertex a to an edge ab, then graphs and FGs cannot answer this question. Therefore, in this research article, we proposed the idea of CC for FIG. Because in FIG, we can find CC from vertex a to vertex b and also from vertex a to an edge ab. Also, we proposed the idea of CC of fuzzy incidence cycles (FICs) and complete fuzzy incidence graphs (CFIGs). The fuzzy incidence cyclic cut-vertex, fuzzy incidence cyclic bridge, and fuzzy incidence cyclic cut pair are established. A condition for CFIG to have fuzzy incidence cyclic cut-vertex is examined. Cyclic connectivity index and average cyclic connectivity index of FIG are also investigated. Three different types of vertices, such as cyclic connectivity increasing vertex, cyclically neutral vertex and, cyclic connectivity decreasing vertex, are also defined. The real-life applications of CC of FIG in a highway system of different cities to minimize road accidents and a computer network to find the best computers among all other computers are also provided.
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Fridovich-Keil, David, Andrea Bajcsy, Jaime F. Fisac, et al. "Confidence-aware motion prediction for real-time collision avoidance1." International Journal of Robotics Research 39, no. 2-3 (2019): 250–65. http://dx.doi.org/10.1177/0278364919859436.
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One of the most difficult challenges in robot motion planning is to account for the behavior of other moving agents, such as humans. Commonly, practitioners employ predictive models to reason about where other agents are going to move. Though there has been much recent work in building predictive models, no model is ever perfect: an agent can always move unexpectedly, in a way that is not predicted or not assigned sufficient probability. In such cases, the robot may plan trajectories that appear safe but, in fact, lead to collision. Rather than trust a model’s predictions blindly, we propose that the robot should use the model’s current predictive accuracy to inform the degree of confidence in its future predictions. This model confidence inference allows us to generate probabilistic motion predictions that exploit modeled structure when the structure successfully explains human motion, and degrade gracefully whenever the human moves unexpectedly. We accomplish this by maintaining a Bayesian belief over a single parameter that governs the variance of our human motion model. We couple this prediction algorithm with a recently proposed robust motion planner and controller to guide the construction of robot trajectories that are, to a good approximation, collision-free with a high, user-specified probability. We provide extensive analysis of the combined approach and its overall safety properties by establishing a connection to reachability analysis, and conclude with a hardware demonstration in which a small quadcopter operates safely in the same space as a human pedestrian.
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Bolshakov, D. Yu. "On relations in science: the case of the scientific journal editorial board." Scholarly Research and Information 4, no. 1-2 (2021): 23–32. http://dx.doi.org/10.24108/2658-3143-2021-4-1-2-19-28.
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This article analyses the connections between members of the editorial board of a scientific journal which are formed based on their reviews of scientific articles. It is shown that the connections can be represented as a graph. The research uses the data for six years of article reviewing in the scientific and technical Journal of "Almaz — Antey" Air and Space Defence Corporation.The methods of analysis are combinatorics and graph theory, as well as the relevant graph characteristics: adjacency matrix, incidence matrix, reachability matrix, graph fullness and connectivity, nearest neighbours graph and graph spanning tree.It is shown that cooperation of the reviewers of the Journal helps plot a connected graph with links between any two vertices, i.e. between any reviewers.The graph is analysed and the methods of its application to calculate the Journal’s scientometric indicators are demonstrated. As the research reveals, a journal that publishes articles in numerous disciplines forms connections between all reviewers and this parameter can be indicative of interchangeability within the scientific fields or, conversely, of a joint work in this scientific field when reviewing manuscripts. Based on the research results, it is possible to search for new reviewers in the areas where competencies are underdeveloped. And by the areas where competencies are strong, we can determine the core competence of the reviewers of a scientific journal, reflecting the main focus of the evaluated scientific research.The work resulted in the formulated scientometric indicators of the journal, which can be used to search for and involve new reviewers or to represent data on a strong team of reviewers on a specific topic, as well as on a new scientific field just emerging for research.
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Meyer, Pierre-Jean. "Reachability Analysis of Neural Networks with Uncertain Parameters." IFAC-PapersOnLine 56, no. 2 (2023): 4822–27. http://dx.doi.org/10.1016/j.ifacol.2023.10.1249.
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Sundar, S., and Z. Shiller. "Constrained Optimization of Multi-Degree-of-Freedom Mechanisms for Near-Time-Optimal Motions." Journal of Mechanical Design 116, no. 2 (1994): 412–18. http://dx.doi.org/10.1115/1.2919394.
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This paper presents a method to design multi-degree-of-freedom mechanisms for near-time optimal motions. The design objective is to select system parameters, such as link lengths and actuator sizes, that will minimize the optimal motion time of the mechanism along a given path. The exact time-optimization problem is approximated by a simpler procedure that maximizes the acceleration near the end points. Representing the directions of maximum acceleration with the acceleration lines, and the reachability constraints as explicit functions of the design parameters, we transform the constrained optimization to a simpler curve-fitting procedure. This problem is formulated analytically, permitting the use of efficient gradient-based optimizations instead of the zero order optimization that is otherwise required. It is shown that with the appropriate choice of variables, the reachability constraints for planar mechanisms are linear in the design parameters. Consequently, the reachability of the entire path can be guaranteed by satisfying the reachability of only two extreme points along the path. This greatly simplifies the optimization problem since it reduces the dimensionality of the constraints and it permits the use of efficient projection methods. Examples for optimizing the dimensions of a five-bar planar mechanism demonstrate close correlation between the approximate and the exact solutions and better computational efficiency of the constrained optimization over previous penalty-based methods.
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Sukhanov, A. V. "The Output of a Group of Aircraft to a Given Position at a Given Time." Mekhatronika, Avtomatizatsiya, Upravlenie 25, no. 6 (2024): 315–19. http://dx.doi.org/10.17587/mau.25.315-319.
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The article considers an algorithm for controlling a group of aircraft providing a given location of aircraft in space at a given time. When controlling a group of unmanned aerial vehicles, it is often necessary to bring them to the specified positions at a given time. Reachability areas and optimal control methods can be used to bring aircraft to specified positions. The application of reachability domains for solving problems of controlling a group of aircraft is considered. The article also provides an analysis of the method of calculating the reachability areas and an example of calculating the reachability areas of a rocket. A problem for a group of aircraft is considered, for which reachability domains are used in a group way. Aircraft with specific characteristics and initial parameters are used for modeling. The task is solved in two stages. The reachability regions in the vertical plane are approximated by triangles. The equations were integrated by the Runge-Kutta method with a constant step. For an aircraft whose motion is determined by a system of equations with a control constraint under given initial conditions, it is necessary to define a control program that provides a minimum of functionality. Thus, the optimal control problem is reduced to a boundary value problem: to find a solution to a system of equations whose phase coordinates satisfy the initial conditions and boundary conditions. In addition, according to the maximum principle, the Hamilton function under optimal control should reach a maximum. Moreover, the control must satisfy the restriction. The construction of reachability areas and the choice of programs based on the maximum principle makes it possible to bring a group of aircraft to a given position at a given time.
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Sidorenko, Gennady. "External Estimators of the Reachability Set of Nonlinear Discrete Systems." Bulletin of Baikal State University 29, no. 1 (2019): 107–12. http://dx.doi.org/10.17150/2500-2759.2019.29(1).107-112.
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On the one hand, nonlinear discrete systems are natural generalization of linear discrete systems. On the other hand, various economic and, especially, technical systems have, basically, a nonlinear nature. Therefore, research of mathematical models of these systems is a relevant issue for implementing various procedures of systems analysis and decision making. Clusters of trajectories of the considered systems can be generated both by the parameters interpreted as control circuits, and by the parameters interpreted as perturbations. Quite general results of reachability sets estimation of nonlinear discrete systems, including a number of well-known achievements in this field as a consequence, are offered. As specification of these approaches, quadratic estimators of the reachability set of nonlinear discrete systems are received.
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Yu, Ai Bing, Nan Zhao, Yan Lin Wang, and Xin Li Tian. "Interpretative Structural Modeling for Ceramic Grindability System." Key Engineering Materials 359-360 (November 2007): 194–98. http://dx.doi.org/10.4028/www.scientific.net/kem.359-360.194.
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Based on systematic engineering theory and method, interpretative structural model of ceramic grindability system was set up. Property parameters, grinding parameters and grindability indexes were selected as system elements. The adjacency matrix between system elements was constructed. The reachability matrix was calculated according to adjacency matrix. By calculation of reachability matrix and classification, interpretative structural model of the ceramic grindability system was obtained. The system model could describe the relationship between the ceramic grindability and system elements. The grindability system model also provides a fundamental theoretical reference for the research on the grindability of ceramic materials. The weight of each influencing factor of ceramic grindability can be calculated by applying the system model. The grindability of ceramic materials can be evaluated objectively and comprehensively.
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Amigó, José M., Guillem Duran, Ángel Giménez, José Valero, and Oscar Martinez Bonastre. "Modeling a New AQM Model for Internet Chaotic Behavior Using Petri Nets." Applied Sciences 11, no. 13 (2021): 5877. http://dx.doi.org/10.3390/app11135877.
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Formal modeling is considered one of the fundamental phases in the design of network algorithms, including Active Queue Management (AQM) schemes. This article focuses on modeling with Petri nets (PNs) a new scheme of AQM. This innovative AQM is based on a discrete dynamical model of random early detection (RED) for controlling bifurcations and chaos in Internet congestion control. It incorporates new parameters (α,β) that make possible better stability control over oscillations of an average queue length (AQL) at the router. The PN is validated through the matrix equation approach, reachability tree, and invariant analysis. The correctness is validated through the key properties of reachability, boundedness, reversibility, deadlock, and liveness.
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Huang, Yushen, Ertai Luo, Stanley Bak, and Yifan Sun. "Reachability analysis for linear systems with uncertain parameters using polynomial zonotopes." Nonlinear Analysis: Hybrid Systems 56 (May 2025): 101571. https://doi.org/10.1016/j.nahs.2024.101571.
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Rauh, Andreas, and Julia Kersten. "Transformation of Uncertain Linear Systems with Real Eigenvalues into Cooperative Form: The Case of Constant and Time-Varying Bounded Parameters." Algorithms 14, no. 3 (2021): 85. http://dx.doi.org/10.3390/a14030085.
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Continuous-time linear systems with uncertain parameters are widely used for modeling real-life processes. The uncertain parameters, contained in the system and input matrices, can be constant or time-varying. In the latter case, they may represent state dependencies of these matrices. Assuming bounded uncertainties, interval methods become applicable for a verified reachability analysis, for feasibility analysis of feedback controllers, or for the design of robust set-valued state estimators. The evaluation of these system models becomes computationally efficient after a transformation into a cooperative state-space representation, where the dynamics satisfy certain monotonicity properties with respect to the initial conditions. To obtain such representations, similarity transformations are required which are not trivial to find for sufficiently wide a-priori bounds of the uncertain parameters. This paper deals with the derivation and algorithmic comparison of two different transformation techniques for which their applicability to processes with constant and time-varying parameters has to be distinguished. An interval-based reachability analysis of the states of a simple electric step-down converter concludes this paper.
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Smolka, Bogdan, and Damian Kusnik. "On the application of the reachability distance in the suppression of mixed Gaussian and impulsive noise in color images." Multimedia Tools and Applications 79, no. 43-44 (2020): 32857–79. http://dx.doi.org/10.1007/s11042-020-09550-w.
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Abstract In this paper, we address the problem of mixed Gaussian and impulsive noise reduction in color images. A robust filtering technique is proposed, which is utilizing a novel concept of pixels dissimilarity based on the reachability distance. The structure of the denoising method requires the estimation of the impulsiveness of each pixel in the processing block using the introduced local reachability concept. Furthermore, we determine the similarity of each pixel in the block to the central patch consisting of the processed pixel and its neighbors. Both measures are calculated as an average of modified reachability distances to the most similar pixels of the central patch and the final filtering output is a weighted average of all pixels belonging to the processing block. The proposed technique was compared with widely used filtering methods and the performed experiments proved its satisfying denoising properties. The introduced filtering design is insensitive to outliers and their clusters introduced by the impulsive noise process, preserves details and is able to efficiently suppress the Gaussian noise while enhancing the image edges. Additionally, we proposed a method which estimates the noise contamination intensity, so that the proposed filter is able to adaptively tune its parameters.
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Shehata, Mohamed Ghazy. "New Sliding Mode Controller Based on Second Order Reachability Law." Applied Mechanics and Materials 704 (December 2014): 357–61. http://dx.doi.org/10.4028/www.scientific.net/amm.704.357.
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Sliding mode control systems provide robust and simple means for controlling linear and nonlinear plants whose parameters may vary within known boundaries. The existence of an ideal sliding mode requires fast switching, which induces chattering in the system, may excite high frequency plant dynamics and consequently affect the stability of the system. This paper proposes a new simple sliding mode controller based on second order reachability law. The reachability condition in this paper is based not only on the first derivative of the switching function but also on its second derivative. The proposed controller alleviates chattering, guarantees zero steady state error, and offers smooth transients for the system states. To demonstrate the validity of the proposed controller, a second order system is used as a workbench example. The simulation results of the workbench example using MATLAB illustrate the feasibility and efficacy of the proposed controller.
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Yeung, Chung-Kwong, Kwok-Wai Lam, Jo Lai-Ken Cheung, et al. "Overcoming Abdominal and Pelvic Cavity Workspace Constraints in Robotic-Assisted NOTES." Journal of Robotics 2020 (May 18, 2020): 1–8. http://dx.doi.org/10.1155/2020/8590539.
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Despite early enthusiasm in robotic-assisted NOTES, several technical challenges exist. Various spinopelvic anatomical constraints can significantly act as obstacles and affect entry and space availability for the deployment of straight and rigid transvaginal/transanal NOTES instruments. Anatomical constraints such as the sacral slope, position, and distance to the target organs are defined. Transvaginal access to the surgical site required a high insertion angle between 20° and 30° to overcome the pronounced sacral slope resulting in dexterity and reachability limitations. A new set of robotic parameters was generated to introduce a 7 degrees of freedom robotic arm. Workspace simulation and phantom precision measurements have shown a significant improvement in the reachability and maneuverability of the robotic platform. While the robotic arms provided stable dexterity, it is constrained when reaching target sites in larger patients. This study has provided an insight and a solution in rigid instrument design, paving a safe route for transvaginal/transanal access for abdominal surgeries towards robotic-assisted NOTES.
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Ramos-Paja, Carlos Andres, Juan David Bastidas-Rodriguez, and Andres Julian Saavedra-Montes. "Sliding-Mode Control of a Photovoltaic System Based on a Flyback Converter for Microinverter Applications." Applied Sciences 12, no. 3 (2022): 1399. http://dx.doi.org/10.3390/app12031399.
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A method to design a sliding-mode control of a photovoltaic system based on a flyback converter is proposed. First, the photovoltaic system is modeled to design the sliding-mode controller and to select the parameters of a maximum power point tracking algorithm. Then, the detailed design of the sliding-mode controller is presented, which includes the establishment of the sliding surface. The transversality, reachability, and equivalent control tests are also developed. Because the power extraction of the PV system is carried out through a P&O MPPT algorithm, the selection of the perturbation magnitude, the perturbation period, and the maximum switching frequency is integrated into the control design. Additionally, since the derivative of the MPPT output could prevent the achievement of the reachability test, a filter to limit that derivative is also integrated into the design process. The whole method is illustrated in an application example where the data of a BP585 PV module and a real flyback converter are used. Once the parameters were obtained, circuital simulations performed in PSIM validated the intended operation of a PV system composed of a PV module and a flyback converter, which is connected to a source that produces the perturbations of an AC grid.
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Zhao, Haijuan, Juan Ma, and Qinqi Xu. "A Novel Asynchronous Sliding Mode Design for Switched Systems under Input–Output Finite-Time Stability." Electronics 12, no. 21 (2023): 4519. http://dx.doi.org/10.3390/electronics12214519.
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In this work, the input–output finite-time stability (IO-FTS) of a class of continuous-time switched systems characterized by uncertainties and subjected to external disturbances is studied under asynchronous switching by means of the sliding mode control (SMC) method. The IO-FTS poses a finite-time constraint problem, which involves addressing two main issues: firstly, ensuring that the state trajectory of the switched system reaches the given sliding mode surface within the specified time, and secondly, achieving IO-FTS for the closed-loop switched system during asynchronous switching. To address these issues, we apply a partitioning strategy and construct asynchronous sliding mode controllers with adjustable parameters to ensure the reachability of the system’s state trajectory within a finite time. Subsequently, we employ a multiple Lyapunov function (MLF) approach to provide sufficient conditions that ensure IO-FTS during the whole phase [0,T] for the resulting switched system. Additionally, we analyze the asynchronous characteristics concerning the reachability phase of the designed sliding surface, considering the system’s switching properties. Finally, we demonstrate the efficacy of the proposed approach with a numerical example.
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Schmitt, Jochen, Leonie Sundmacher, Boris Augurzky, et al. "Krankenhausreform in Deutschland: Populationsbezogenenes Berechnungs- und Simulationsmodell zur Planung und Folgenabschätzung." Monitor Versorgungsforschung 2024, no. 03 (2024): 37–50. http://dx.doi.org/10.24945/mvf.03.24.1866-0533.2606.
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Background: Due to the increasing shortage of specialists, disproportionately rising costs and inadequate quality of care, Germany is planning a fundamental hospital reform. The government commission has developed the central principles for this reform. The aim is to achieve a centralization of hospital services in oversupplied metropolitan areas by planning according to groups of services based on defined requirements for structural quality. The economic pressure to increase the number of cases shall be reduced through the introduction of a reserve payment and by dividing hospitals into levels - at least by transparent information for the general public. So far, however, there has been no generic model to determine the significance of specific care providers considering population needs (reachability), capacity of a hospital location, and the number and severity of treated patients. Methods: We developed a generic model to determine the significance of hospital location-related care and the need for the various groups of services. The model may also be used to assess reserve financing. For the model, the groups of services were divided into four categories according to degree of specialization and urgency with limits of reachability of 30, 45, 90 and 180 minutes. Gravity models were used to simulate the population-based significance of care providers for each group of services. In the basic model, the allocation of the significance was based exclusively on the reachability for the population living within the respective reachability corridor. In extended models, the historical number of cases and their case severity were also taken into account in order to account for current care capacities and existing choices of the population regarding, among other things, the quality of care. The model was implemented on the basis of nationwide data provided in accordance with § 21 data (of the German law for hospital remuneration). We then determined the effects of weighting the three influencing variables (i) population, (ii) number of cases and (iii) case severity on the significance of the hospital sites. Using the example of "endoprosthetics of the knee" (service group 14.2 in North Rhine-Westphalia) in the federal state of Saxony, the effect of concentration on the distribution of the reserve budgets and on the accessibility of the population was illustrated. The importance of care determined in this way is contrasted with a key value that reflects the need for hospitals in terms of securing care in rural areas. Results: From the approximately 16.5 million somatic treatment cases in 2021, 98.5% could be assigned to one of the 60 somatic groups of services according to North Rhine-Westphalia model. The simulation models show a differentiated picture for the various service groups. For the majority of service groups, a moderate concentration of services does not lead to relevant restrictions in terms of reachability. Exclusively considering the population to be cared for (basic model) would lead to significant shifts in the financing of running costs, which are, however, very well mitigated by considering the historic number and severity of cases (extended models). As an example, we show the effects for the service group "endoprosthetics of the knee" in the federal state of Saxony compared to the extrapolation at location level. Discussion: The empirically based simulation model proposed here takes into account reachability, patient preference and hospital capacity and offers a scientific way of comparing the regional significance of care providers as well as the necessity of hospital locations for each service group against the background of the state's obligation to provide care and to make economical use of resources. The simulation model is meant to support hospital planning (here: the allocation of groups of services) in the federal states and to guide rational planning. It is also suitable for the management of financial resources in the context of hospital reform. It also enables an impact analysis. The model is not intended to automate planning or otherwise make rigid specifications. The calculations should be regarded as exemplary. The weights of all parameters can be varied. However, the reachability thresholds and the parameterization of the simulation model should be defined jointly by federal and state governments in terms of a common set of objectives.
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Xue, Yan-Mei, Bo-Chao Zheng, and Dan Ye. "Quantized Feedback Control Design of Nonlinear Large-Scale Systems via Decentralized Adaptive Integral Sliding Mode Control." Mathematical Problems in Engineering 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/718924.
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A novel decentralized adaptive integral sliding mode control law is proposed for a class of nonlinear uncertain large-scale systems subject to quantization mismatch between quantizer sensitivity parameters. Firstly, by applying linear matrix inequality techniques, integral-type sliding surface functions are derived for ensuring the stability of the whole sliding mode dynamics and obtaining the prescribed boundedL2gain performance. Secondly, the decentralized adaptive sliding mode control law is developed to ensure the reachability of the sliding manifolds in the presence of quantization mismatch, interconnected model uncertainties, and external disturbances. Finally, an example is shown to verify the validity of theoretical results.