Inequality Conditions Research Articles

Robust Static Output Feedback with Dynamic Disturbance Feed-forward for Lateral Control of Long-combination Vehicles At High Speeds

Abstract A control strategy is proposed to improve the high-speed lateral performance of an A-double (tractor-semitrailer-dolly-semitrailer) combination vehicle using active steering of the front axle of the dolly. The strategy is realized as a H∞-type static output feedback combined with dynamic feed-forward. The static output feedback synthesis is based on a previous work from the literature, while novel linear matrix inequality (LMI) conditions have been derived for dynamic feed-forward synthesis that can also be used for uncertain systems. The proposed controller has a simple structure and is easy to implement from a practical point of view since it requires only the driver steering angle (for feed-forward) and just one articulation angle measurement (for feedback). Obtained using a high-fidelity vehicle model, the synthesis results confirm a significant reduction in the rearward amplifications of the yaw rate and the lateral acceleration as well as the high-speed transient off-tracking during sudden lane change maneuvers.

Sample-data output-feedback parameter variable control of glucose for type 1 diabetes mellitus patients

This paper presents a new approach for nonlinear sampled-data output-feedback control of blood glucose concentration (BGC) in patients with type 1 diabetes mellitus (T1DM). The Bergman minimal model (BMM) describing the glucose-insulin regulatory system is framed as a linear parameter-varying (LPV) model that the sampled glucose measurement with the quantized insulin infusion is considered as input delay. The proposed method utilizes the input-delay approach based on a parameter-dependent Lyapunov–Krasovskii functional (LKF) and provides the parameterized matrix inequality conditions for the design of the controller. Using the slack variables, the design conditions are converted to a new form that can achieve feasible solutions by solving a limited number of bilinear matrix inequality. The proposed architecture guarantees stability in a compact set of states for all the trajectories with the parametric uncertainty to address the issue of inter-patient variability. Simulation results confirm that the proposed sampled-data static output-feedback LPV controller with only glucose measurement regulates the BGC despite the parametric uncertainty and meal disturbances in T1DM patients.

Necessary and sufficient admissibility conditions of dynamic output feedback for singular linear fractional‐order systems

AbstractThis paper studies the stabilization problem for linear continuous‐time singular fractional‐order systems with the fractional‐order satisfying . New formulations of the admissibility for the closed‐loop system by dynamic output feedback controller are obtained using necessary and sufficient (linear matrix inequality) conditions, to generalize existing results in the literature for integer‐order systems. The derived results are validated by numerical examples demonstrating applicability and efficacy of the presented approach.

Entre hedores fecales urbanos, miseria y enfermedades intestinales en Cuernavaca

The underdeveloped urban structure of Cuernavaca deserves to review the serious social effects caused by discharge untreated wastewater into the ravines. That the conditions of urban inequality, poverty and patterns of water pollution associated with human health in this city, would act as a replicable sample with the 780 million people in the underdeveloped world who do not have access to drinking water, with the 2,500 million without sanitation, or, with the 2,000 million that are supplied with drinking water with fecal pathogenic agents.

Fault-Tolerant Periodic Event-Triggered Consensus Under Communication Delay and Multiple Attacks

This article proposes a resilient strategy for leaderless and leader–following consensus in general linear multiagent systems under simultaneous presence of false data injection and denial-of-service (DoS) attacks. To save energy, local control updates and communication between the neighboring agents are based on a distributed periodic event-triggered scheme. Sufficient conditions to guarantee the exponential mean square bounded consensus are derived as linear matrix inequality (LMI) conditions obtained from some delay-dependent Lyapunov–Krasovskii functionals. The proposed design framework computes the required consensus control gain based on a desired level of resilience to DoS. The guaranteed level of resilience in our proposed LMI-based method is less conservative (more realistic) compared to the existing analytical solutions. Two physical constraints, namely nonuniform time-varying communication delay and actuator faults, are also included in the problem formulation to enhance the practicability of the proposed solution. Simulations results demonstrate the effectiveness of the proposed framework in the presence of the considered cyberthreats and physical constraints.

Women's experiences along the ovarian cancer diagnostic pathway in Catalonia: A qualitative study.

Early detection of symptoms and prompt diagnosis of ovarian cancer are considered important avenues for improving patient experiences and outcomes. This qualitative study used a phenomenological approach to perform patient interviews, collecting individual accounts of the prediagnostic phase in women diagnosed and treated for ovarian cancer in 2016-2017. Purposive sampling was used to obtain a diverse sample of 24 participants, while thematic content analysis was used to extract themes and subthemes from interview data. Three themes and nine subthemes were identified. The first theme was women's delay in recognizing symptoms and seeking care, with subthemes on the lack of knowledge about early signs of ovarian cancer, gender-related barriersand false reassurance from negative test results. A second theme was missed opportunities during healthcare encounters, due to misattribution of women's symptoms by their physicians, underestimation of symptom severity and need for mediationand inadequate tests and/or false negative results. Finally, interviews highlighted the use of resources and alternative healthcare pathways, including complementary/alternative medicines, access to private health careand women's capacity for action and decision-making (agency) about their health. Delayed diagnosis of ovarian cancer is rooted in both individual factors (lack of health literacy, reluctance to seek care) and systemic issues (missed opportunities in healthcare encounters, access to timely specialist care). Further research is needed to investigate the extent to which traditional gender roles and socioeconomic inequalities condition women's ability to manage their own health and to interact with health professionals and the health system. In addition to the patient participation during the interviews, one author was a representative of a patient association.

CONCEPTUALIZATION OF DIGITAL MANAGEMENT AS A MODERN TREND

The article is aimed at exploring theoretical aspects of designing a digital management system as a tool for the inclusion of the country in the global system of division of labor and the international cooperation system. The author has found out that digitalization processes substantially affect the system of global division of labor and create conditions for digital inequality, which requires new approaches to management of organizational systems. The article considers the possibilities of digital management initially focused on the activation of inclusion of organizational systems in global division of labor and cooperation processes at a new level of managerial efficiency as such an approach. Keywords: digital management, management, division of labor, cooperation, activation, transformation.

Disturbance observer-based nonfragile fuzzy tracking control of a spacecraft

This paper deals with the nonfragile fuzzy tracking control technique of a spacecraft subject to external disturbances and control gain uncertainties. First, the Takagi–Sugeno (T–S) fuzzy model of the tracking error dynamics is newly derived. Unlike the existing studies, we assume that the controller output is norm bounded and its gain matrix is perturbed because of the aging of the actuator. Next, a fuzzy disturbance observer (DOB) estimating the external disturbance is constructed to enhance the robustness of the control system. Then, a fuzzy controller feeding back the estimated disturbance is designed to attenuate external disturbances. In addition, we establish the linear matrix inequality (LMI) conditions, by which both the H∞ disturbance attenuating performance and the asymptotic stabilization are guaranteed. From the solution to the LMI conditions, we obtain the controller and DOB gain matrices. Finally, a simulation example validates the disturbance estimation and tracking performance of the proposed method.

Linear matrix inequality–based observer design methods for a class of nonlinear systems with delayed output measurements

This article deals with observer design for a class of nonlinear systems subject to delayed output measurements. Using an observer structure borrowed from Targui et al., we propose novel linear matrix inequality conditions ensuring the asymptotic convergence of the estimation error towards zero. We demonstrate analytically that the established linear matrix inequalities are less conservative than that of Targui et al., from a feasibility viewpoint, in the sense that they tolerate larger values of the upper bounds of the delay while guaranteeing the asymptotic convergence of the observer. Such linear matrix inequality conditions are obtained due to the use of a specific Lyapunov–Krasovskii functional, the Young inequality in a judicious way and a reformulation of the Lipschitz condition in a convenient way. We provide two illustrative examples to support the efficiency and superiority of the proposed linear matrix inequality–based techniques.

A Dynamically Dimensioned Search Allowing a Flexible Search Range and Its Application to Optimize Discrete Hedging Rule Curves

The discrete hedging rule for reservoir operation includes time-varying trigger volumes used for the onset and termination of water rationing, which complicates its optimization problems. A dynamically dimensioned search can be easily applied to complex optimization problems, but the performance is relatively limited in constrained optimization problems such as deriving reservoir operation rules. A dynamically dimensioned search allowing for a flexible search range is proposed in this study to efficiently solve constrained optimization problems. The modified algorithm can recursively update the search ranges of decision variables with limited overlaps. The above two algorithms are applied to derive hedging rule curves for three reservoirs. Objective function values are closely converged to optimum solutions, with fewer evaluations using the modified algorithm than those using the traditional algorithm. The modified algorithm restrains an overlapped search range of decision variables and can reduce redundant computational efforts caused by unreasonable candidate solutions that violate inequality conditions.

Analysis and Design of Robust Controller for Polynomial Fractional Differential Systems Using Sum of Squares

This paper discusses the robust stability and stabilization of polynomial fractional differential (PFD) systems with a Caputo derivative using the sum of squares. In addition, it presents a novel method of stability and stabilization for PFD systems. It demonstrates the feasibility of designing problems that cannot be represented in LMIs (linear matrix inequalities). First, sufficient conditions of stability are expressed for the PFD equation system. Based on the results, the fractional differential system is Mittag–Leffler stable when there is a polynomial function to satisfy the inequality conditions. These functions are obtained from the sum of the square (SOS) approach. The result presents a valuable method to select the Lyapunov function for the stability of PFD systems. Then, robust Mittag–Leffler stability conditions were able to demonstrate better convergence performance compared to asymptotic stabilization and a robust controller design for a PFD equation system with unknown system parameters, and design performance based on a polynomial state feedback controller for PFD-controlled systems. Finally, simulation results indicate the effectiveness of the proposed theorems.

Adaptive event‐triggered resilient stabilization for nonlinear semi‐Markov jump systems subject to DoS attacks

AbstractThis article investigates the problem of adaptive event‐triggered resilient stabilization for nonlinear semi‐Markov jump systems with DoS attacks. In this article, both DoS attacks and event‐triggered transmission strategy (ETTS) are considered. The DoS attacks may disturb the event‐triggered strategy, which implies that the original inequality condition of ETTS will no longer be satisfied. Different from the traditional ETTS, the adaptive ETTS is designed to reduce bandwidth usage. Based on the adaptive ETTS and resilient controller, the sufficient condition for stochastic stability of the closed‐loop system is proposed. Then, the calculation method of controller and observer parameters is given in the form of linear matrix inequality. Finally, the proposed adaptive event‐triggered resilient controller is applied to a single‐link robot arm model, which can show effectiveness of the proposed method.

Two novel stability criteria for linear systems with interval time-varying delays

This paper analyses the stability problem of linear systems with interval time-varying delay. In regard to the delay, it has the lower and upper bounds and its derivative is unknown or itself is not differentiable. First of all, it is the first time that the delay-related triple integral terms are used to construct the augmented Lyapunov–Krasovskii functional (LKF) and the delay-related integral quadratic terms are estimated by the third-order free-matrix-based integral inequalities (TFIIs). Then, based on the same LKF and same TFIIs and by introducing two sets of state vectors, the derivative of the LKF is presented as the quadratic and quintic polynomials about the delay respectively. Next, for the quadratic and quintic polynomials, new negative definite conditions (NDCs) are provided to form the linear matrix inequality (LMI) conditions. Finally, the advantages of these two criteria are checked through some classical numerical examples.

Special issue on PID control in the information age: Theoretical advances and applications

Special issue on PID control in the information age: Theoretical advances and applications

Event-based control of a damped linear wave equation

This paper aims at proposing a sufficient matrix inequality condition to carry out the global exponential stability of the wave equation under an event-triggering mechanism that updates a damping source term. The damping is distributed in the whole space but sampled in time. The well-posedness of the closed-loop event-triggered control system is shown. Furthermore, the avoidance of Zeno behavior is ensured provided that the initial data are more regular. The interest of the results is drawn through some numerical simulations.

Observer‐based finite‐time H∞ control of Itô‐type stochastic nonlinear systems

AbstractThis paper investigates the finite‐time control of Itô‐type stochastic nonlinear systems. Considering the transient performance and anti‐interference ability within a given limited time interval, the control strategy of stochastic nonlinear systems is researched. A new sufficient condition for mean‐square finite‐time boundedness for stochastic nonlinear system is developed. Due to the state components are not available, a state observer is designed. Based on the estimated state, an controller is proposed and Linear Matrix Inequality (LMI) conditions are given, which not only guarantee the mean‐square finite‐time boundedness but also satisfy the corresponding performance. Finally, two examples are given to demonstrate the effectiveness of the results.

Fixed-Time Stabilization of Delayed Discontinuous Fuzzy Neural Networks via Delayed Stability Conditions of Filippov Systems

This article aims to propose time-delayed and simplified inequality conditions and establish more novel fixed-time (FXT) stability principles of delayed Filippov systems. First, the sign function is used to unify the orders of the Lyapunov–Krasovskii functional, and the time-delayed term is introduced in the inequality conditions, then some new FXT stability theorems are established and new estimations of the settling time involving delayed parameter are given that are absolutely different from the previous ones. The traditional inequality conditions <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\dot{V}(z)\leq -aV^\alpha (z)-bV^\beta (z)$</tex-math></inline-formula> is optimized and improved. For the purpose of illustrating the applicability, a class of delayed discontinuous fuzzy Cohen–Grossberg neural networks (DDFCGNNs) is studied. Some new criteria are derived, and the FXT stabilization of the addressed DDFCGNNs is achieved. Finally, a representative example and simulations are provided to examine the correctness.

Finite-Time Stabilization of Linear Systems With Unknown Control Direction via Extremum Seeking

In this article, the finite-time stabilization problem is solved for a linear time-varying system with unknown control direction by exploiting a modified version of the classical extremum-seeking algorithm. We propose to use a suitable oscillatory input to modify the system dynamics, at least in an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">average</i> sense, so as to satisfy a differential linear matrix inequality condition, which in turn guarantees that the system’s state remains inside a prescribed time-varying hyperellipsoid in the state space. The finite-time stability (FTS) of the averaged dynamics implies the FTS of the original system, as the distance between the original and the averaged dynamics can be made arbitrarily small by choosing a sufficiently high value of the dithering frequency used by the extremum-seeking algorithm. The main advantage of the proposed approach resides in its capability of dealing with systems with unknown control direction, and/or with a control direction that changes over time. Being FTS a quantitative approach, this article also gives an estimate of the necessary minimum dithering/mixing frequency provided, and the effectiveness of the proposed finite-time stabilization approach is analyzed by means of numerical examples.

Dampak IPM, tingkat pengangguran dan tingkat kemiskinan terhadap ketimpangan pendapatan di Sumatera Bagian Selatan

This study aims to analyze the development of the Human Development Index (HDI), Unemployment Rate, Poverty Levels in the Southern Sumatra Region, analyze the condition of regional development inequality in the Southern Sumatra Provinces and analyze the influence of the Human Development Index (IPM), Unemployment Rate, Level of Poverty on income inequality in southern Sumatra in 2010-2019. This research is a quantitative research. The data used is a cross section of 5 provinces in Southern Sumatra and time series for 2010-2019. The data is processed by panel data analysis with fixed effect regression model. Based on the results of the HDI panel data regression test, the unemployment rate and poverty rate have a significant effect on income in Southern Sumatra. All research variables have a simultaneous effect on income inequality. Partially, the HDI variable and the poverty level have no effect on income inequality, while from the research variable only the Unemployment Rate has a negative effect on income inequality.

Female squirrel monkeys’ (Saimiri boliviensis) responses to inequity in a group context; testing a link between cooperation and inequity responses

Primates of several species respond negatively to receiving less preferred rewards than a partner for completing the same task (inequity responses), either rejecting rewards or refusing to participate in the task when disadvantaged. This has been linked to cooperation, with species that cooperate frequently refusing to participate in inequity tasks (the 'cooperation hypothesis'). However, inequity is a social response, and previous research has involved dyads, precluding studying the effects of additional social partners. While dyads allow for tighter control in experimental settings, dyadic interactions in nature do not take place in a social vacuum, so understanding the role of the social context is needed to verify that the pattern of results supports the cooperation hypothesis. Here we focus on Bolivian squirrel monkeys, Saimiri boliviensis, a highly social species that does not generally cooperate and has not responded to inequity in previous dyadic research, although they do respond to receiving a lower reward than they expected. In the current study, we provide a more nuanced test by studying female Bolivian squirrel monkeys, the demographic most likely to cooperate in both field and laboratory contexts, in a more socially relevant group setting. For some reward values, females responded in both the inequity condition, rejecting less preferred rewards when they were disadvantaged relative to their social group, and a contrast condition, wherein all animals received a lower reward than they expected, making it difficult to disentangle contrast from inequity. As in capuchin monkeys, refusals increased when monkeys were to receive low-value rewards compared to medium-value rewards. These results suggest that the relationship between cooperation and inequity responses may be more nuanced than previously suggested, with demographic, social context and reward value potentially influencing outcomes even within species.