Practical Stability Research Articles

Passivating Grain Boundary Defects with Tris(hydroxymethyl)aminomethane to Achieve Efficient and Stable Tin-Based Perovskite Solar Cells

Although tin (Sn)-based perovskite is regarded as a good substitute for a lead-based analogue due to its environmental friendliness and suitable band gap, Sn-based perovskite solar cells (PSCs) still need to overcome practical stability and efficiency problems. Here, a passivation material tris(hydroxymethyl)aminomethane (THAM) with amino and multihydroxyl groups is added into the formamidinium tin iodide (FASnI3) perovskite to reduce the defect state density and unnecessary nonradiative recombination of the film, which eventually not only improves the light absorption ability and film crystallinity but also inhibits the oxidation of Sn2+. Applications of the THAM-doped FASnI3 perovskite films into PSCs acquire a high power conversion efficiency of 9.18%. Moreover, the storage stabilities of PSCs are obviously prolonged because of the improved Sn-based perovskite film quality, showing excellent stability of 550 h to keep 85% of its initial efficiency (in an N2 environment).

Semi-passivity and practical stability for switched discrete-time nonlinear systems

This paper concerns semi-passivity and practical stability of a switched discrete-time nonlinear system. First, semi-passivity concept is proposed to achieve broader application. It means that each subsystem is passive outside a ball on its active time interval. Then, practical stability of switched nonlinear system is obtained by investigating the energy changing of the inactive subsystem. Second, semipassivity conditions are given. Based on these conditions, a more general switching law than ‘min’ switching law is designed to achieve semi-passivity. Third, the feedback semipassification problem for such a system is solved by designing a set of controllers and a switching law dependent on state. Finally, the validity of the obtained result is verified by its application to a thermal system.

A Financial Model of the 100% Medicare Practice

Payment & Practice Management| June 2023 A Financial Model of the 100% Medicare Practice Johnathan Pregler, MD, FASA; Johnathan Pregler, MD, FASA Search for other works by this author on: This Site PubMed Google Scholar Mahesh Vaidyanathan, MD, MBA; Mahesh Vaidyanathan, MD, MBA Search for other works by this author on: This Site PubMed Google Scholar David S. Larsen, MD, FASA; David S. Larsen, MD, FASA Search for other works by this author on: This Site PubMed Google Scholar Michael C. Lewis, MD, FASA; Michael C. Lewis, MD, FASA Search for other works by this author on: This Site PubMed Google Scholar Elmer Choi, MD, PhD, MBA, FASA; Elmer Choi, MD, PhD, MBA, FASA Search for other works by this author on: This Site PubMed Google Scholar Christopher J. Young, MD, FASA; Christopher J. Young, MD, FASA Search for other works by this author on: This Site PubMed Google Scholar Stephen E. Comess, BSN, MHSA Stephen E. Comess, BSN, MHSA Search for other works by this author on: This Site PubMed Google Scholar ASA Monitor June 2023, Vol. 87, 1–6. https://doi.org/10.1097/01.ASM.0000938772.47169.77 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn Email Cite Icon Cite Get Permissions Search Site Citation Johnathan Pregler, Mahesh Vaidyanathan, David S. Larsen, Michael C. Lewis, Elmer Choi, Christopher J. Young, Stephen E. Comess; A Financial Model of the 100% Medicare Practice. ASA Monitor 2023; 87:1–6 doi: https://doi.org/10.1097/01.ASM.0000938772.47169.77 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll PublicationsASA Monitor Search Advanced Search Topics: medicare, economics What are the implications of a single-payer health system in which private insurance would be eliminated and practice finances would be solely based on Medicare as it exists today. This paradigm would be a unique and especially problematic issue for anesthesiologists. Presently, the profession is faced by an inimitable discrepancy in the Medicare payments for anesthesia services. This is known as the “33% Problem.” While Medicare reimbursement payments for other specialties represent between 75% and 85% of their commercial rates, compensation for anesthesia services is less than one-third of commercial rates. In fact, recently it has been concluded by some that actual Medicare payments are probably in the mid-20% range. If this was the universal payment system, it would introduce a significant threat to the long-term stability of most anesthesiology practices. Many groups address the compensation “shortfall” described above by negotiating to fill the revenue gap with payments from hospitals.... You do not currently have access to this content.

Practical Finite-Time Sampled-Data Output Feedback Stabilization for a Class of Upper-Triangular Nonlinear Systems With Input Delay

Practical Finite-Time Sampled-Data Output Feedback Stabilization for a Class of Upper-Triangular Nonlinear Systems With Input Delay

Implantable smart hyperthermia nanofibers for cancer therapy: Challenges and opportunities.

Nanofibers (NFs) with practical drug-loading capacities, high stability, and controllable release have caught the attention of investigators due to their potential applications in on-demand drug delivery devices. Developing novel and efficient multidisciplinary management of locoregional cancer treatment through the design of smart NF-based systems integrated with combined chemotherapy and hyperthermia could provide stronger therapeutic advantages. On the other hand, implanting directly at the tumor area is a remarkable benefit of hyperthermia NF-based drug delivery approaches. Hence, implantable smart hyperthermia NFs might be very hopeful for tumor treatment in the future and provide new avenues for developing highly efficient localized drug delivery systems. Indeed, features of the smart NFs lead to the construction of a reversibly flexible nanostructure that enables hyperthermia and facile switchable release of antitumor agents to eradicate cancer cells. Accordingly, this study covers recent updates on applications of implantable smart hyperthermia NFs regarding their current scope and future outlook. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants.

Assessing the role of institutional effectiveness on carbon sequestration: the case of China's nature reserve policy

PurposeCarbon storage in protected land is a practical climate stabilization strategy. It is increasingly being recognized as an essential means of safeguarding biomass carbon and improving local ecological conditions. Yet, increasing soil carbon sequestration by setting aside nature reserves does not depend only on the scale of the reserve but more so on the implementation and enforcement of the reserve protection policy. This paper aims to discuss the aforementioned issues.Design/methodology/approachThe authors show how nature reserves established and managed by different administrative levels affect carbon sequestration. Empirically, the authors estimate a time-varying difference-in-difference model that exploits China's distinct four-layered hierarchical nature reserve management system at the county level.FindingsThe findings show that higher administrative level (i.e. national and provincial) nature reserves have no effects on the carbon dynamic. However, reserves managed by lower administrative levels (i.e. prefecture- and county-level) are associated with reduced carbon sequestration. The results imply local governments fail to fulfil their responsibilities for nature reserves protection, leading to increased extractive activities and declined ecological biomass. Research limitations/implicationsResponsibility and accountability mechanisms for the violation of the nature reserves requirements need to be stipulated accordingly. Greater emphasis should be placed on nature reserves at the base level. The central government should continue efforts toward the establishment of ad hoc and independent management agencies at the ground-management level that are free of influence from base-level governments.Originality/valueThe heterogeneity in the performance of nature reserves across administrative levels confirms that ecosystem service quality is highly dependent on establishment, management and supervision. This provides a better understanding of the socio-ecological interdependence of protected areas.

Practical semiglobal uniform exponential stability of nonlinear nonautonomous systems

UDC 517.9 We solve the following twofold problem: In the first part, we deduce Lyapunov sufficient conditions for practical uniform exponential stability of nonlinear perturbed systems under different conditions for the perturbed term. The second part presents a converse Lyapunov theorem for the notion of semiglobal uniform exponential stability for parametrized nonlinear time-varying systems. We establish the possibility of application of a perturbed parametrized system, by using Lyapunov theory, to the investigation of the robustness properties that may provide practical semiglobal uniform exponential stability with respect to perturbations.

Practical Exponential Stability of Two Dimensional Nonlinear Switched Positive Systems in the Roesser Model

Practical Exponential Stability of Two Dimensional Nonlinear Switched Positive Systems in the Roesser Model

Boosting oxygen reduction catalysis by introducing Fe bridging atoms between Pt nanoparticles and N-doped graphene

Introducing heterometals into Pt/C catalyst to construct multi-metal catalyst for improving the intrinsic activity is a rational strategy which can optimize the over-strong *O adsorption of Pt nanoparticles for oxygen reduction reaction (ORR). However, the practical activity and stability of such carbon supported Pt-based bimetallic catalysts are simultaneously limited by the conductivity degradation and deactivation caused by the weaker interaction between Pt and carbon support. Herein, by taking advantage of the precise control and self-limiting reaction of atomic layer deposition, we construct a novel Pt-Fe-NG structure in which Fe atoms play the bridging role between Pt nanoparticles and the N-doped graphene by multistep deposition. Impressively, the obtained catalyst exhibits an outstanding ORR half-wave potential of 0.948 V, a total four-electron pathway and superior durability over 10,000 cycles. The mass activity of the catalyst at 0.9 V is 15 times higher than that of commercial Pt/C. Moreover, when used as the cathode catalyst of Zn-air battery, the Pt-Fe-NG performs a maximum density power of 230 mW cm-2 and excellent stability after 180 discharge–charge cycles. The experimental results and theoretical calculations indicate that Fe bridging atoms play the role of elevating the d-band center of Pt nanoparticles and enhancing the interaction between Pt nanoparticles and carbon support, which paves a pathway for constructing novel multi-metal catalysts.

Novel ZnO/Ag nanohybrids prepared from Ag+-doped layered zinc hydroxides as highly active photocatalysts for the degradation of dyes and Ciprofloxacin

The design and the synthesis of highly active nanohybrid photocatalysts for environmental remediation is a topical issue in the context of sustainable development. The hybridization of a semiconductor with noble metal nanoparticles (NPs) has been demonstrated to be a versatile strategy to restrict the recombination of photogenerated electron-hole pairs and thus increase the photocatalytic activity. However, the uniform association of nanosized metal particles with ZnO NPs remains a challenge. Herein, a novel synthesis of ZnO NPs hybridized with Ag(0) NPs is presented. Ag+-doped layered zinc hydroxides (LZHs) were prepared in aqueous solution in the presence of triethanolamine and subsequently Ag+ ions were photoreduced into metallic Ag NPs embedded into LZHs. The LZHs not only promote the dispersion of Ag NPs but also limit their growth. The Ag(0)-doped LZHs obtained after hydrothermal treatment was finally transformed into ZnO/Ag nanohybrids by a mild thermal treatment at 300 °C for 5 min, which allows high interface coupling between ZnO and Ag NPs. ZnO associated with 3 mol% Ag exhibits the highest photocatalytic activity for the degradation of dyes (Rhodamine B and Remazol Brillant Blue R) and of the Ciprofloxacin antibiotic. The high photocatalytic performance of the ZnO/Ag(3) nanohybrid originates from the charge transfer in the ZnO/Ag nanohybrid and from the enhanced harvesting of visible light. The ZnO/Ag(3) photocatalyst also exhibits a high practical stability, indicating its great potential for real photocatalytic applications.

Formulation of Impulsive Ecological Systems Using the Conformable Calculus Approach: Qualitative Analysis

In this paper, an impulsive conformable fractional Lotka–Volterra model with dispersion is introduced. Since the concept of conformable derivatives avoids some limitations of the classical fractional-order derivatives, it is more suitable for applied problems. The impulsive control approach which is common for population dynamics’ models is applied and fixed moments impulsive perturbations are considered. The combined concept of practical stability with respect to manifolds is adapted to the introduced model. Sufficient conditions for boundedness and generalized practical stability of the solutions are obtained by using an analogue of the Lyapunov function method. The uncertain case is also studied. Examples are given to demonstrate the effectiveness of the established results.

Quantized control for switched systems suffered by deception attacks and unknown disturbance

AbstractThe purpose of this paper is designing a feedback controller based on quantized sampled data to stabilize a continuous‐time switched system affected by unknown disturbance and deception attacks. Suppose that the switch is slow enough in the sense of dwell‐time and average dwell‐time, and the attacker's energy is limited by restraining the number and duration of deception attacks, we design a communication and control strategy based on mode switching and data tampering. By approximating the reachable set for the stabilizing stage and searching stage, respectively, we establish the increasing/decreasing rate of Lyapunov function under different cases. On this basis, the sufficient conditions which constrain average dwell‐time and sampling period are obtained to ensure the exponential decay and practical stability of the closed‐loop system. Furthermore, we also verify that the searching stage can be recovered within an unknown limited time under the influence of unknown disturbance and deception attacks. Two‐tank system is adopted at last to show the effectiveness of the proposed algorithm framework.

A Method for Risk Assessment Evaluating the Safety, Stability and Efficacy in Clinical Practice of Anticancer Drug Preparations in the Centralized Compounding Unit of the Veneto Institute of Oncology-IRCCS.

Preparation of injectable anticancer drugs in hospital pharmacies is a high-risk activity that requires a proper risk assessment (RA) and quality assurance system (QAS) to ensure both a decrease in risk associated with chemotherapy compounding and high quality of the final product, especially in terms of its microbiological stability. At the centralized compounding unit (UFA) of the Italian Hospital IOV-IRCCS, a quick and deductive method was applied to evaluate the "added value" provided by each prescribed preparation, and its RA was calculated applying a formula that integrates different pharmacological, technological and organizational aspects. According to specific RA range values, the preparations were divided into different risk levels, in order to determine the QAS to be adopted, according to the Italian Ministry of Health guidelines, whose adherence was meticulously evaluated through a specific self-assessment procedure. A review of the scientific literature was carried out to integrate the risk-based predictive extended stability (RBPES) of drugs with data concerning their physiochemical and biological stability. Based on the self-assessment comprising all microbiological validations of the working area, personnel and products, the microbiological risk level within the IOV-IRCCS' UFA was defined through the creation of a transcoding matrix, conferring a microbiological stability to preparations and vial leftovers of a maximum of 7 days. The calculated RBPES were successfully integrated with stability data from the literature, leading to the drafting of a stability table of drugs and preparations in use in our UFA. Our methods allowed us to perform an in-depth analysis of the highly specific and technical process of anticancer drug compounding in our UFA, ensuring a certain grade of quality and safety to preparations, especially in terms of microbiological stability. The resulting RBPES table represents an invaluable tool with positive repercussions at organizational and economic levels.

Output Feedback Control for Spacecraft Attitude System with Practical Predefined-Time Stability Based on Anti-Windup Compensator

This paper investigates the problem of output feedback attitude control for rigid spacecraft subject to inertia matrix uncertainty, space disturbance, and input saturation. Firstly, a model transformation is adopted to convert an attitude system with immeasurable angular velocity into a new system. All states of the new converted system are measurable and available for feedback; however, the system contains mismatched uncertainty resulting from the coordinate transformation. Then, an adaptive nonsingular back-stepping control with practical predefined-time convergence is designed. To resolve the problem of input saturation, an anti-windup compensator is developed. It is analytically proved that the spacecraft attitude and angular velocity are practical predefined-time stable, such that the convergence time is a given tunable constant. The simulation results reveal that the proposed control framework provides rapid attitude maneuver and actuator saturation elimination.

Design and test of a multi capacity integrated HTS thin film reconfigurable current limiter

This paper proposes and tests the YBa2Cu3O7-x (YBCO) thin film based multi capacity integrated high temperature superconducting thin film reconfigurable current limiter (HTS-TFRCL). Generally, reconfigurable concepts are widely employed in the microwave communication and antenna fields to design and fabricate the device with multiple operation performance, by choosing different circuit structures. Thus reconfigurable concept can be employed in the design of HTS thin film current limiter integrated different limiting capacity in one thin film device against the different levels of fault current. Considering there is few relevant work focused on the application of reconfigurable concept design in HTS current limiting field, the YBCO thin film based HTS-TFRCL is proposed and tested for the first time in this paper. It can be found from preliminary verification experiment carried out in our laboratory that, the proposed HTS-TFRCL has the multi current limiting capacity (its current limiting capacities are 50 VA, 90 VA, 120 VA, and 170 VA at 65 VAC, respectively), it can operate as expected to limit the fault currents under different voltages. Therefore, the HTS-TFRCL proposed in this paper can offer the multiple current limiting modes and capacities to limit the different levels of fault current, according to the practical operation requirements, the compactness, fabricating cost, stability and reliability of the current protection system can be further improved.

Finite time course keeping control for unmanned surface vehicles with command filter and rudder saturation

This paper studies the problem of course keeping control for unmanned surface vehicle (USV) with servo dynamic characteristics, environmental disturbances and model’s uncertainties, and rudder saturation. Considering the characteristics of the rudder servo system (RSS), a nonlinear Norrbin model with second-order rudder is reconstructed, and proposes a finite time simple and practical course controller by the finite time dynamic surface control (FTDSC) technology, which achieve excellent finite time command filter. Then, the nonlinear disturbance observer (NDOB) is applied to estimate the lumped disturbances, which is easy to implement in engineering. Meanwhile, the bandwidth between the controller and the observer is studied, which affects the convergence speed of the observer. Besides, finite time dynamic auxiliary systems with smooth switching function (FTADS-SSF) is designed to compensate for rudder physical constraints with finite time convergence. Further practical finite time stability analysis indicates that the entire system is uniformly ultimately bounded (UUB). Finally, simulation comparison results have been demonstrated the proposed strategy.

A switched servo constraints control for the smart vibratory roller in unmanned compaction

A novel control method for the smart vibratory roller in the unmanned compaction has been proposed in the paper, in which the traditional path tracking problem of the smart vibratory roller is creatively considered as the servo constraints following issue (one of the frontier topics in the control field of mechanical systems). According to the construction technology, a series of servo constraints are designed for the smart vibratory roller in the various compaction processes. By following the formulated servo constraints, the task of the unmanned compaction could be automatically fulfilled by the smart vibratory roller. In order to ensure the compaction quality in the servo constraints-following, the uncertainties in the unmanned construction may not be ignored by the smart vibratory roller (e.g., the varying stiffness and damping coefficients of the compaction materials, the disturbances of the vibration frequency and the roughness). Those uncertain factors are time-varying and unknown. A robust algorithm is proposed to estimate the real-time information of the uncertainties during the compaction construction. With the estimated uncertainty information, a switched servo constraints control for the unmanned compaction is constructed. The performance of the control system is theoretically verified by the practical stability theory (i.e., uniform boundedness and uniform ultimate boundedness under the compaction uncertainties). The feasibility of the proposed control method is illustrated by the simulation of an unmanned double drum vibratory roller in the compaction construction.

Nonsingular Fixed-Time Control of Nonstrict Feedback MIMO Nonlinear System With Asymptotically Convergent Tracking Error

In this paper, the research on fixed-time tracking control problem of multiple-input multiple-output (MIMO) nonlinear systems with non-strict feedback control structure is carried out. By means of the fuzzy logic systems (FLSs), the unknown system nonlinear dynamics are identified, and the “algebraic loop problem” is solved. Then, through the combination of adaptive back-stepping recursive technology and adding power integration technology, a non-singular fixed-time adaptive tracking control scheme is presented. Under the action of the presented control scheme, the system can track the specified reference signal within a fixed time independent of the initial state of the system, and the tracking control error can converge to zero asymptotically. Next, on the basis of the fixed-time Lyapunov stability theory, the practical fixed-time stability of the closed-loop system is theoretically demonstrated. Finally, two simulations verify the validity and practicability of the proposed control scheme.

Robust Stability Analysis of a Simple Data-Driven Model Predictive Control Approach

In this paper, we provide a theoretical analysis of closed-loop properties of a simple data-driven model predictive control (MPC) scheme. The formulation does not involve any terminal ingredients, thus allowing for a simple implementation without (potential) feasibility issues. The proposed approach relies on an implicit description of linear time-invariant systems based on behavioral systems theory, which only requires one input-output trajectory of an unknown system. For the nominal case with noise-free data, we prove that the data-driven MPC scheme ensures exponential stability for the closed loop if the prediction horizon is sufficiently long. Moreover, we analyze the robust data-driven MPC scheme for noisy output measurements for which we prove closed-loop practical exponential stability. The advantages of the presented approach are illustrated with a numerical example.

Adaptive event-based fixed-time tracking design for strict-feedback nonlinear systems with unknown control coefficients

In this paper, we propose a novel Nussbaum-type design to cope with the problem in nonlinear dynamical systems with unknown control directions. First, a Nussbaum-based Lyapunov analysis for fixed-time stability is investigated to lay the theoretical foundation. On this basis, the Nussbaum-type adaptive backstepping control is designed with dynamic surface filters to avoid repeated differentiation. To further reduce the computational complexity, an event-triggered mechanism is combined with the Nussbaum-type gain design. With the above design schemes, the practical fixed-time stability of the overall feedback systems can be guaranteed with theoretical discussion. Finally, the feasibility of the presented design is validated by two simulation examples made in the end.