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This paper addresses the problem of designing secure control for networked multi-agent systems (MASs) under Denial-of-Service (DoS) attacks. We propose a constructive design method based on the interaction topology. The MAS with a non-attack communication topology, modeled by quasi-Abelian Cayley graphs subject to DoS attacks, can be represented as a switched system. Using switching theory, we provide easily implementable sufficient conditions for the networked MAS to remain asymptotically stable despite DoS attacks. Our results are applicable to both continuous-time and discrete-time systems, as well as to discrete-time systems with variable steps or systems that combine discrete and continuous times. [ABSTRACT FROM AUTHOR]

Summary: In this paper, the secure group consensus is investigated via periodic event‐triggered output feedback control for nonlinear multi‐agent systems subject to multiple attacks, where replay attacks and denial‐of‐service attacks are considered simultaneously. To avoid uninterrupted communication between agents, a novel fixed/switching continuous‐discrete compensator is first put forward by introducing a discrete‐time triggering mechanism in relative output signals. Then, with the help of the gain control technique, a compensator‐based periodic event‐triggered secure control protocol is established, which includes a triggering mechanism and an output feedback controller that both are discrete‐time. Particularly, Zeno behavior and continuous monitoring of the triggering function are naturally avoided compared with existing event‐triggered control protocols. Further, by combining the Lyapunov‐Krasovskii functional approach with switching topology theory, the secure group consensus is successfully achieved under the designed secure control protocol, meanwhile, the negative effect of multiple attacks on the system is compensated. Finally, two simulation examples are applied to verify the effectiveness of proposed control protocols. [ABSTRACT FROM AUTHOR]

Among the long-standing efforts to elucidate the physical mechanisms of protein- ligand catch bonding, particular attention has been directed at the family of selectin proteins. Selectins exhibit slip, catch-slip, and slip-catch-slip bonding, with minor structural modifications causing major changes in selectins' response to force. How can a single structural mechanism allow interconversion between these various behaviors? We present a unifying theory of selectin-ligand catch bonding, using a structurally motivated free energy landscape to show how the topology of force-induced deformations of the molecular system produces the full range of observed behaviors. We find that the pathway of bond rupture deforms in non-trivial ways, such that unbinding dynamics depend sensitively on force. This implies a severe breakdown of Bell's theory-a paradigmatic theory used widely in catch bond modeling-raising questions about the suitability of Bell's theory in modeling other catch bonds. Our approach can be applied broadly to other protein-ligand systems. [ABSTRACT FROM AUTHOR]

Mobile payment (m-payment) is no longer an unknown technological innovation due to mobile technology advancement. While many past studies have been conducted in this area, they assume that a user will only need to consider m-payment without cash impediments. Hence, they fail to consider the influence of cash within the study of m-payment. Given this limitation, the study draws on migration, regret, innovation resistance, status quo bias, and incentive theories to examine the switching intention from cash to m-payment based on a push-pull-mooring framework. A total of 250 usable sample sizes were adopted, with the conceptual model empirically validated using a PLS-SEM. All the findings in this study were supported except for the relationship between perceived monetary rewards and switching intention, and the risk barrier and inertia. The findings of this study benefit managers and practitioners from both theoretical and practical backgrounds. [ABSTRACT FROM AUTHOR]

Harvey's (1978) switching theory has been widely used to theorize investments in the built environment. Crucially, in switching theory no distinction has been made between investments in the construction of the newly built environment and investments into the existing built environment. The distinction between these two types of switching is key to unveiling the relations between how value is produced, rents are extracted and interest payments are made as investments flow with the real estate sector, and the implications that such switching has for displacement. I discuss the distinction between different types of switching and the implications thereof by analysing the ebb and flow of investments in Spanish real estate from 2000 to 2007 and from 2014 to 2018. On the one hand, I claim that the two switching waves were qualitatively different in so far as capital was fixed in the built environment through the construction of new buildings between 2000 and 2007, whereas from 2014 to 2018 capital was fixed in existing buildings. In the first switching phase, value was produced and land rents were extracted, whereas the second switching phase was characterized mainly by rent extraction. On the other hand, the first switching moment entailed an increase in housing provision, whereas the second switching moment led to widespread displacement of the population. [ABSTRACT FROM AUTHOR]

Quine showed in Quine (1953) that unate Boolean functions have properties not shared by general functions. Among such properties are the uniqueness of their irredundant sum-of-products representation and the relative ease with which this representation can be obtained. This paper investigates to what extent such properties extend to functions that are unate only in a subset of variables. Some results seem to stand out. For instance, subproducts of unate variables form a "prefix set" which does not depend on the particular irredundant sum-of-product representation. A second result is that every sum-of-products expression is decomposable into parts, one per prefix, that can be minimized independently. Finding the shortest expression can then be (recursively) decomposed into smaller subproblems, a departure from traditional monolithic approaches (McCluskey, 1986; Brayton et al., 1984). The results lead naturally to the definition of the class of block-unate functions, Such functions have a unique irredundant sum-of-products representation, which can be recognized and constructed from a truth table or a minterm list in polynomial time. This is a departure from the general construction problem, which is NP-complete (Allender et al., 2008; Umans et al., 2006). [ABSTRACT FROM AUTHOR]

Starting from a reformulation of the mass balance law based on the Bilby–Kröner–Lee (BKL) decomposition of the deformation gradient tensor, we study some peculiar mechanical aspects of growth in a monophasic continuum by regarding the reformulated mass balance equation as a non-holonomic and rheonomic constraint. Such constraint restricts the admissible rates of the growth tensor, i.e., one of the two factors of the BKL decomposition, to comply with a growth law provided phenomenologically. For our purposes, we put the constraint in Pfaffian form, and treat time as a fictitious, additional Lagrangian parameter, subjected to the condition that its rate must be unitary. Then, by taking some suggestions from the literature, we assume the existence of generalized forces conjugated with the virtual variations of the growth tensor, and we write a constrained version of the Principle of Virtual Work (PVW) that leads to a mixed boundary value problem whose unknowns are the motion, the growth tensor, and the Lagrange multipliers of the considered theory. This allows to extrapolate a physical interpretation of the role that the growth-conjugated forces play on the components of the growth tensor, especially on the distortional ones, i.e., those that are not directly related to the variation of mass of the body. The core message of our work is conceptual: we show that the growth laws usually encountered in the literature, which are prescribed phenomenologically, but may be difficult to justify theoretically, can be put in the framework of the PVW by regarding them as constraints. Moreover, we retrieve more particularized frameworks of growth available in the literature, while being able to switch to a theory of growth of grade one, such as a Cahn–Hilliard model of growth. [ABSTRACT FROM AUTHOR]

Random jump of network communication topology challenges the tracking accuracy of linear switched reluctance motor (LSRM) system. This paper studies the pilot‐following consensus control of the multiple direct‐drive motion system (MDDMS) with semi‐Markov jump topology. The mathematical model of LSRM is constructed and the multi‐phase excitation strategy is studied. The directed graph is used to model the information transmission among the leaders and follower, and a new mechanism consensus based on previous states is provided. A consensus system based on semi‐Markov jump topology is constructed and the problem of consensus is shifted into a problem of stability analysis. A sufficient condition for consensus problem is obtained by using semi‐Markov switching system theory and graph theory. The MDDMS achieves consensus in the form of exponential convergence under the designed consensus controller. Several groups of simulation results verify the effectiveness of the proposed consensus control method. [ABSTRACT FROM AUTHOR]

This research note reviews theories of religious switching and polarization and presents data from national studies to trace how the determinants of religious switching have played out in the lives of US Jews. The growing shares of the most religious and the most secular segments, particularly among the young, explain the hollowing of the middle, and the shifts in the denominational landscape of American Jewry. Utilizing primarily Pew Research Center's 2013 and Pew Research Center's 2020 surveys, this note explores the consequences of religious polarization on cohesion among US Jews broadly and with respect to Israel specifically. [ABSTRACT FROM AUTHOR]

Non-equilibrium work switching simulations and Jarzynski's equation are a reliable method for computing free energy differences, Δ A low → high , between two levels of theory, such as a pure molecular mechanical (MM) and a quantum mechanical/molecular mechanical (QM/MM) description of a system of interest. Despite the inherent parallelism, the computational cost of this approach can quickly become very high. This is particularly true for systems where the core region, the part of the system to be described at different levels of theory, is embedded in an environment such as explicit solvent water. We find that even for relatively simple solute–water systems, switching lengths of at least 5 ps are necessary to compute Δ A low → high reliably. In this study, we investigate two approaches towards an affordable protocol, with an emphasis on keeping the switching length well below 5 ps. Inserting a hybrid charge intermediate state with modified partial charges, which resembles the charge distribution of the desired high level, makes it possible to obtain reliable calculations with 2 ps switches. Attempts using step-wise linear switching paths, on the other hand, did not lead to improvement, i.e., a faster convergence for all systems. To understand these findings, we analyzed the solutes' properties as a function of the partial charges used and the number of water molecules in direct contact with the solute, and studied the time needed for water molecules to reorient themselves upon a change in the solute's charge distribution. [ABSTRACT FROM AUTHOR]

A novel method for measuring the complex magnetic susceptibility of magnetic nanoparticles (MNPs) has been developed by a broadband microstrip line-type probe with a frequency range of up to 50 GHz. Two external orthogonal DC fields, Hhard and Heasy, were applied to change the susceptibility of MNPs (Streptavidin coated, 200 nmϕ, number of MNPs about 1010) based on magnetization switching theory. The susceptibility of MNPs in the liquid, solid state, and after biotin-avidin reaction with polymer beads (2 μmϕ, number of polymer beads about 108) was evaluated. A clear FMR frequency of MNPs and the same FMR frequency shift trend as Hhard changed was observed around 2–10 GHz in both liquid and solid states. The susceptibility of MNPs reached maximum when Hhard was 0.1 T which is approximately equal to Heasy (0.135 T). The maximum values of real and imaginary parts increased by a factor of 3.39 and 1.66 compared to when Hhard was 0. The obtained results indicate that the magnetic anisotropy was successfully controlled in the liquid and solid states of MNPs aggregate. Furthermore, after the biotin-avidin reaction of MNPs with polymer beads, the imaginary part of susceptibility showed a decreasing trend regardless of the increase in Hhard, and its half-width expanded by 35.1% at maximum when Hhard was 0.15 T. [ABSTRACT FROM AUTHOR]

Two-dimensional topological insulator bismuth selenide (Bi2Se3) nanosheets (NSs) embedded in poly-methyl methacrylate (PMMA) are employed for the first time for the resistive switching (RS) application. Hexagonal 2D Bi2Se3 NSs are synthesized by a simple solvothermal method and combine with PMMA at different weight percentages of 2D Bi2Se3. Field emission scanning electron microscopy and transmission electron microscopy along with other characterizations such as X-ray photoelectron spectroscopy and Raman spectroscopy were performed for the characterization of Bi2Se3@PMMA hybrid system. The composite was deposited on a transparent, flexible polyethylene terephthalate substrate to form Ag/Bi2Se3@PMMA/indium doped tin oxide memory cell. I-V characteristics of the device revealed a stable and non-volatile memory effect. The device shows a significantly high resistance (RHRS/RLRS) ratio, more than 103, high retention time (more than 9000 s) with high reproducibility over a large number of (105) ac cycles. From the experimental data, RS performances are explained by using a charge trapping–detrapping mechanism. Owing to the increasing interest in flexible electronics, bending tests are carried out at various bending diameters (10–30 mm) to show the mechanical robustness of the proposed device. [ABSTRACT FROM AUTHOR]

Lithium niobate single-crystal films are interesting for the integration of optoelectronic and surface acoustic wave devices. However, the domains have the preferred orientations, which limit their application in non-volatile memory devices. Here, we fabricated 5% Mg-doped LiNbO3 single-crystal films by ion-slicing of surface layers of bulk lithium niobate single-crystals. The Mg doping can improve the electrical performance of the films with the appearance of a definitive coercive voltage irrespective of applied voltages in polarization-voltage (P-V) hysteresis loops, unlike the undoped films where the apparent coercive voltages in P-V hysteresis loops equal the maximum applied voltages. Subsequent unipolar pulse stressing shows comprehensive charge injection into the films to occur at repetitive periodicities below 0.5 s that can symmetrize P-V hysteresis loops along the voltage axis. The injected charge in contradiction to an internal imprint field can change domain switching dynamics that can be described by the model of a non-ferroelectric passive layer in series with an ideal ferroelectric layer. The dielectric permittivities at low frequencies show the Maxwell-Wager relaxation of the injected charge with the broad distribution of relaxation times. As the periodicity is above 2 s, the injected charge within each cycle can be driven out of the film during intermittent time by the imprint field. This study shows the possibility of charge injection in stabilization of bipolar domain orientations in LiNbO3 single-crystal films. [ABSTRACT FROM AUTHOR]

When we study the Karnaugh map in the switching theory course, we learn that the ones in the map are combined in rectangles whose length and width must be a power of two. The result is the logic function described as a sum of products. This paper shows that we can also make groups where the length and width of the rectangles are equal to three. This results in a logic function that is simpler than the sum of products in terms of logic gates, leading to more hardware-efficient circuits. This idea is extended later in the paper to other groups of elements. Finally, a new perspective on the Karnaugh map that integrates the proposed approach with the conventional one is provided. This can be used in switching theory courses to improve the explanation of the Karnaugh map. [ABSTRACT FROM AUTHOR]

A mixed graph is a set of vertices together with an edge set and an arc set. An (m; n)-mixed graph G is a mixed graph whose edges are each assigned one of m colours, and whose arcs are each assigned one of n colours. A switch at a vertex v of G permutes the edge colours, the arc colours, and the arc directions of edges and arcs incident with v. The group of all allowed switches is Γ. Let k ≥ 1 be a fixed integer and Δ a fixed permutation group. We consider the problem that takes as input an (m,n)- mixed graph G and asks if there is a sequence of switches at vertices of G with respect to Δ so that the resulting (m,n)-mixed graph admits a homomorphism to an (m,n)-mixed graph on k vertices. Our main result establishes that this problem can be solved in polynomial time for k ≤ 2, and is NP-hard for k ≥ 3. This provides a step towards a general dichotomy theorem for the Δ-switchable homomorphism decision problem. [ABSTRACT FROM AUTHOR]

This article presents a Bayesian approach for sequential detection of anomalies in the motion of a target and joint tracking. The anomaly is modeled as a binary (on/off) switching unknown control input that goes into action (begins to exist, or "switches on") thereby modifying the object dynamics; and by ceasing its activity (becoming nonexistent, or "switching off") returns the dynamics to nominal. The developed Bayesian framework brings together random finite set (RFS) theory to represent the switching nature of the anomaly, and optimal joint input and state estimation to sequentially update a hybrid state that incorporates a random vector for the kinematic state and a Bernoulli RFS for the unknown control input. In addition, a closed-form solution, the Gaussian-mixture hybrid Bernoulli filter (GM-HBF), has been developed to provide a customized solution for dynamic anomaly detection in the maritime domain characterized by linear Gaussian target dynamics. Based on the Ornstein–Uhlenbeck dynamic model for vessels, where the evolution of the object velocity is governed by a piecewise mean-reverting stochastic process, the anomaly can be represented by a change in the long-run mean velocity (i.e., the unknown control input) from the nominal condition that forces the vessel to deviate from its standard route. We demonstrate the effectiveness of the proposed GM-HBF in both simulated and real-world maritime surveillance applications and test its performance in the face of false measurements, detection uncertainty, and sensor data gaps. [ABSTRACT FROM AUTHOR]

Keywords: Boolean function; discrete Fourier (Walsh-Hadamard) transform; maximum nonlinearity; amplitude; dimension of a Boolean function; extension of general affine group EN Boolean function discrete Fourier (Walsh-Hadamard) transform maximum nonlinearity amplitude dimension of a Boolean function extension of general affine group 177 192 16 06/17/22 20220601 NES 220601 Note: Originally published in Diskretnaya Matematika (2021) 33,No2, 66-85 (in Russian). Discrete Fourier (Walsh-Hadamard) transform, dimension of a Boolean function, extension of general affine group, Boolean function, maximum nonlinearity, amplitude It is important to note the value of group invariants in problems connected to classification of Boolean functions. [Extracted from the article]

In this study, we consider a new aspect of belief function or Dempster-Shafer theory to define a belief set and cosine similarity measure between two belief sets under uncertainty. For this purpose, firstly, the concept of belief sets will be represented as a triple vector space that is characterized by truth-belief degree, uncertainty-belief degree; and falsity-belief degree. Then, the cosine similarity measure between two belief sets is proposed to determine the degree of similarity between them. This measure is directly defined upon the framework of Dempster-Shafer theory without switching by other theories. Finally, an application of a new method in the decision-making process is provided in the medical diagnosis, when values were presented on the structure of belief set. Furthermore, a numerical example of the medical diagnosis is presented to show the effectiveness and flexibility of the proposed method. [ABSTRACT FROM AUTHOR]

In this work, atomically K1−xNaxNbO3 thin films are taken as examples to investigate the reversible and irreversible effects in a horizon plane, i.e., the changes of domain structures, phase states, free energies, etc., under a z-axis alternating current field via a phase-field method. The simulation results show the driving forces during the charging and discharging process, where there is a variation for the angles of the domain walls from 180° to 90° (and then an increase to 135°), which are the external electric field and domain wall evolution, respectively. As for the phase states, there is a transformation between the orthorhombic and rhombohedral phases which can't be explained by the traditional polarization switching theory. This work provides a reasonable understanding of the alternating current field effect, which is essential in information and energy storage. [ABSTRACT FROM AUTHOR]

Summary: This article investigates the tracking control problem for a kind of chained‐form nonholonomic systems in the presence of unknown time‐varying disturbances and full‐state constraints. First, a finite‐time tracking controller is constructed to drive the action of relay switching, which converts the whole control system into two design stages. In order to handle with the predefined asymmetric state constraints, the original tracking error system is turned into an unconstrained system on the basis of state‐dependent function (SDF) function transformations. In this framework, an adaptive tracking control strategy is proposed by means of backstepping and dynamic surface control. Correspondingly, another tracking control law is also constructed to assure the stability of the tracking error system before the action of switching. The theoretical analysis of stability indicates that the proposed tracking control scheme can guarantee that the output state tracking errors converge to zero and the desired state constraints are not violated. At the same time, all the closed‐loop system signals maintain bounded in entire control process. Finally, the validity of the presented tracking control algorithm is demonstrated by simulation and experiment results. [ABSTRACT FROM AUTHOR]

Twitter has become a popular means of communication used in a variety of fields. This widely used platform has an impact on the way people express themselves and is changing language usage worldwide at an unprecedented pace. This article investigates the reasons for the use of French–English language mixing among French users on Twitter using a topic analysis approach. This analysis draws on Gumperz's theory of conversational switching. In order to collect tweets at a large scale, the data were collected in R using the rtweet package. A total of nine topic categories were identified and analyzed in this article: entertainment, internet/social media, events/community, politics/news, sports, sex/pornography, innovation/technology, fashion/makeup, and business. This study finds that entertainment is the most frequent topic discussed on Twitter. English words, such as trailer, spoil, and live are found in the data. This study enables a deeper understanding of users' linguistic behavior online, and offers insights into future trends in intercultural and cross-language exchanges. [ABSTRACT FROM AUTHOR]

The operating principle of resistive random access memories (RRAMs) relies on the distribution of ionic species and their influence on the electron transport. Taking into account that formation and annihilation of conducting filaments (CFs) is the driving mechanism for the switching effect, it is very important to control the regions where these filaments will evolve. Thus, homolayers of titanium oxide with different oxygen contents were fabricated in order to tune the local electrical and thermal properties of the CFs and narrow down the potential percolation paths. We show that the oxygen content in the top layer of the TiO2-x/TiO2-y bilayer memristors can directly influence the morphology of the layers which affect the diffusion barrier and consequently the diffusivity and drift velocity of oxygen vacancies, yielding in important enhancement of switching characteristics, in terms of spatial uniformity (σ/μ<0.2), enlarged switching ratio (~104), and synaptic learning. In order to address the experimental data, a physical model was applied, divulging the crucial role of temperature, electric potential and oxygen vacancy density on the switching effect and offering physical insights to the SET/RESET transitions and the analog switching. The forming free nature of all the devices in conjunction with the self-rectifying behavior, should also be regarded as important assets towards RRAM device optimization. [ABSTRACT FROM AUTHOR]

Cu2O film based single sandwich structure with complementary resistive switching characteristics is demonstrated. Unlike the conventional complementary resistive switching devices, the Pt/Cu2O/fluorine doped tin oxide sandwich structure is fabricated without anti-serially bipolar resistive switching cells or interfacial layer. In addition, the forming-step is unnecessary to turn on the device, which makes the complementary resistive switching process easy to control. With high resistance ratio, stable retention and reproducible switching properties, this complementary resistive switching device can be used in three dimensional stacked crossbar memory arrays. The switching mechanism is also discussed by developing a conductive path model. [ABSTRACT FROM AUTHOR]

In industrial machinery, position-controlled systems executing repetitive tasks are of significant importance. In such mechanisms, the load-side inertia and torque vary with the angular position of the driven axis, thus imposing a significant nonlinearity in the system dynamics. Linear controllers have a relatively low computational time, but are unable to achieve the required performance over the whole operating region. Nonlinear controllers, such as nonlinear model predictive control (NLMPC), demand an extensive computational time that is difficult to bound. The current Soft Switching Multiple MPC (SSM-MPC) techniques rely solely on the gap metric or weighting techniques to guarantee soft switching between controllers. However, in nonlinear systems with fast dynamics, it may result in poor performance and/or high computational time. In this work, we have addressed these issues by introducing an overlapping cross-over time strategy in the switching unit of the SSM-MPC to ensure a smooth transition when switching in adjacent regions. The key idea behind the overlapping cross-over time strategy is introducing a delay i.e. cross-over time during switching. The cross-over time helps to improve the completeness and non-redundancy of the model bank. The closed loop system stability is guaranteed using Lyapunov theory and a general switching stability proof is provided. The proposed SSM-MPC performance is benchmarked against the available SSM-MPC method and a single linear MPC on a high speed industrial pick and place machine through simulations and experiments. The results verify the superior performance of the presented SSM-MPC with 37.67% reduction in tracking error and 20.36% decrease in control signal oscillations at the highest operating speed of the machine compared to the available SSM-MPC technique without cross-over time. Moreover, in contrast to the nonlinear MPC, it is proven that the computational load of the SSM-MPC is 77.5% lower, which allows implementation in a standard industrial controller. • Introducing the cross-over time for seamless transitions between multiple linear MPCs. • Tailored MPC for nonlinear systems: fast dynamics with strict real-time requirements. • Computationally efficient control method for industrial PLCs. • A general switching stability proof is provided. [ABSTRACT FROM AUTHOR]

This paper proposes a robust multi-model predictive control strategy to solve the path-following control problem of unmanned surface vehicles (USVs) in wide-range speed variations. The dynamic characteristics of USVs tend to vary greatly in wide-range speed variations. A discrete piecewise affine system with polytopic uncertainty is established to describe the speed and steering dynamics characteristics of USVs in wide-range speed variations. Then, an improved adaptive line-of-sight (IALOS) guidance law is designed to adapt the USV maneuvering characteristics in different speed ranges, which features a variable look-ahead distance subject to speed and lateral error. Finally, the speed and heading controllers are designed by combining the multi-model switching control theory and the robust model predictive control algorithm based on linear matrix inequalities (LMIs), and the stability proofs are given. Comparative numerical simulations are performed to validate the effectiveness and superiority of the proposed control strategy. • Dynamic characteristics variations resulting from wide-range speed variations are considered in the path-following control of USV. • A piecewise affine system with polytopic uncertainty is established to guarantee the fidelity and simplicity of the USV dynamic model in wide-range speed variations. • An improved adaptive LOS guidance law is designed to guarantee good dynamic and static path-following performance in wide-range speed variations. • Multi-model predictive speed and heading controllers are designed to guarantee good robustness and input constraint treatment in wide-range speed variations. [ABSTRACT FROM AUTHOR]

In this article, the output consensus tracking problem for a class of heterogeneous multiagent systems (HMASs) with intermittent communications is studied. We first design a local observer for each agent to estimate unmeasurable state information of followers', and an adaptive distributed estimator is constructed for each follower to estimate the leader's state. Then a type of switched and distributed tracking controllers for HMASs are established under the intermittent communications, and relative parameters of the novel controllers are designed via the constructed regulation equation. Furthermore, by using the switching system theory and LMI technology, both the sufficient conditions for HMASs to achieve output consensus tracking and the threshold of communication rate are obtained, and simultaneously the controller gain and observer gain matrices are constructed. Finally, a simulation example is provided for general HMASs to verify the correctness and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Summary: This study presents a power‐enhanced cascaded half‐bridge (HB) diode clamped transformer‐less multilevel inverter for grid‐connected large‐scale photovoltaic (PV) system addressing the problem of unequal power in isolated diode clamped (DC)‐link due to partial shading. The HB diode clamped has the feasibility of increasing double times the DC‐link voltage compared with the conventional cascaded h‐bridge to enhance the inverter's power rating without compromising the count and peak inverse voltage of switching devices. Under partial shading conditions, the DC‐link of individual HB suffers from different voltages and leads to unbalanced capacitor voltages. The proposed control scheme stabilizes the DC‐link voltage of individual HB, extracts maximum active power from PV, and injects the same into the grid. The injected grid current total harmonic distortion satisfies the IEC 61727 and IEEE 1547 standards. PV parasitic capacitance in the transformer‐less grid‐connected system leads to leakage current. In the present work, LC‐filters are placed among the power cells to bring these currents below 30 mA as per German standards VDE V 0126‐1‐1. For the planned inverter, a mathematical model using the switching function theory has been derived. The inverter's performance has been tested under partial shading conditions by using the MatLab/Simulink platform and experimentally verified with the software‐in‐the‐loop real‐time digital simulator OPAL‐RT 5700. [ABSTRACT FROM AUTHOR]

We study the formation of bands of colloidal particles driven by periodic external fields. Using Brownian dynamics, we determine the dependence of the band width on the strength of the particle interactions and on the intensity and periodicity of the field. We also investigate the switching (fieldon) dynamics and the relaxation times as a function of the system parameters. The observed scaling relations were analyzed using a simple dynamic density-functional theory of fluids. [ABSTRACT FROM AUTHOR]

We proposed a basic resistance-switching mechanism for Mott memory based on the SiO2:Pt system to explain why device performance depends on the electrode. The competition between collection current and drift current in SiO2:Pt system was attributed to the polarity of the set voltage depending on the work function of the electrode. The proposed theory, based on the energy band of SiO2:Pt calculated using first-principles calculations, explains the perplexing phenomenon wherein a SiO2:Pt device cannot show reproducible resistance-switching behavior with a symmetric electrode. The theoretical set voltage agrees with prior experimental results, which verifies our theory. [ABSTRACT FROM AUTHOR]

Despite their partial ionic nature, many-layered diatomic crystals avoid internal electric polarization by forming a centrosymmetric lattice at their optimal van der Waals stacking. Here, we report a stable ferroelectric order emerging at the interface between two naturally grown flakes of hexagonal boron nitride, which are stacked together in a metastable non-centrosymmetric parallel orientation. We observe alternating domains of inverted normal polarization, caused by a lateral shift of one lattice site between the domains. Reversible polarization switching coupled to lateral sliding is achieved by scanning a biased tip above the surface. Our calculations trace the origin of the phenomenon to a subtle interplay between charge redistribution and ionic displacement and provide intuitive insights to explore the interfacial polarization and its distinctive “slidetronics” switching mechanism. [ABSTRACT FROM AUTHOR]

The bidirectional buck-boost current-fed isolated dc–dc converter (B3CFIdc) has the advantages of low current stress, high efficiency, and wide power/voltage conversion range. The linear models of buck mode and boost mode of B3CFIdc are originally derived using state-space averaging method. The dual-closed-loop control configuration with the inductor current and output voltage is designed. In order to ensure the stability of both operation modes at the same time, the parameters of the controllers are designed using the method of Hurwitz criterion plus frequency response. The asymptotic stability of the operating conditions with periodic switching between the two modes caused by the periodic fluctuation of input voltage is verified using the linear switching theory. The detailed experimental results verify the correctness of the built small-signal models and the feasibility of the designed closed-loop control configuration and the design rule of the controller parameters. [ABSTRACT FROM AUTHOR]

In this paper, we report a multilevel unipolar resistive switching (RS) phenomenon with negative differential resistance (NDR) effect in Ag/SiO2/Pt sandwich structure. After positive electroforming process with low compliance current (ICC, 10nA), a conductive filament consisting of isolated Ag nanocrystals is formed inside SiO2 layer. Then, an abnormal unipolar resistive switching (RESET voltage is larger than SET voltage) with NDR effect is obtained under negative voltage sweep without ICC. Based on I-V fitting and temperature dependence of the resistance results, we suggest that the abnormal unipolar RS is dominated by the charging/discharging of carriers in Ag nanocrystals. In addition, we demonstrate that the unipolar RS exhibits good performances, including large Roff/Ron ratio, high uniformity, long retention time, and multilevel storage potential. [ABSTRACT FROM AUTHOR]

Within the multiagent systems framework, the relative states between neighbors can be acquired by some on-board sensors, and then the relative state saturations inevitably occur due to the limited sensing capabilities. This paper investigates the consensus problem of nonlinear multiagent systems subject to the relative state saturations. Utilizing the incidence matrix and the edge Laplacian, the consensus problem of nonlinear multiagent systems with the relative state saturations can be cast into the stabilization problem of edge dynamics operating on the constrained set. Three types of protocols, namely continuous, intermittent, and adaptive state feedback protocols are, respectively, proposed for achieving the constrained consensus, and meanwhile yielding consensus values. A consensus analysis is provided by virtue of state saturation theory, switched system theory, adaptive theory, and Lyapunov stability theory. Output feedback protocol is also designed. Finally, the obtained results are applied to connectivity preservation for first-order nonlinear multiagent systems, despite the presence of limited communication range and input constraints. The theoretical results are validated by two simulation examples. [ABSTRACT FROM AUTHOR]

For the containment control problem of autonomous surface vehicles with external disturbances, a novel non-singular fixed-time control scheme is developed, where the multi-ship system consists of real leaders and followers. In contrast with traditional containment cases studied in most of the existing literature, real leaders are required to track the desired trajectories, and the followers need to get into the convex hull spanned by the real leaders in a fixed time. The method for solving the fixed-time containment control problem is divided into the following steps: Firstly, a fixed-time disturbance observer is designed to estimate the external disturbance for the leaders and the followers, and the estimation result is used to compensate for the input of the control system; Second, combined with fixed-time stability theory and a switch function, a non-singular fixed-time trajectory tracking controller for leaders is designed, such that the position tracking error could be bounded within a fixed time; Third, to achieve formation efficiently, a non-singular fixed-time containment controller strategy incorporating with graph theory is proposed for coordinating followers, such that the fixed-time stability can be ensured. Finally, simulation examples are given to demonstrate the effectiveness of the proposed method. • This paper addresses the containment control problem of ASVs by two layers, namely, trajectory tracking and containment formation control. • A non-singular control law is proposed for each follower to accomplish the fixed-time tracking with by the fixed-time stability theory and a switch function. • Based on fixed-time stability theory, an observer is is constructed to estimate the external disturbance, which can be achieved in fixed time. [ABSTRACT FROM AUTHOR]

Multilevel programing and charge transport characteristics of intrinsic SiOx-based resistive switching memory are investigated using TaN/SiOx/n++Si (MIS) and TiW/SiOx/TiW (MIM) device structures. Current transport characteristics of high- and low-resistance states (HRS and LRS) are studied in both device structures during multilevel operation. Analysis of device thermal response demonstrates that the effective electron energy barrier is strongly dependent on the resistance of the programed state, with estimates of 0.1 eV in the LRS and 0.6 eV in the HRS. Linear data fitting and conductance analyses indicate Poole-Frenkel emission or hopping conductance in the low-voltage region, whereas Fowler-Nordheim (F-N) or trap-assisted tunneling (TAT) is indicated at moderate voltage. Characterizations using hopping transport lead to hopping distance estimates of ~1 nm in the LRS for both device structures. Relative permittivity values (εr) were extracted using the Poole-Frenkel formulism and estimates of local filament temperature, where εr values were ~80 in the LRS and ~4 in the HRS, suggesting a strongly polarized medium in the LRS. The onset of F-N tunneling or TAT corresponds to an observed "overshoot" in the I-V response with an estimated threshold of 1.660.2 V, in good agreement with reported electroluminescence results for LRS devices. Resistive switching is discussed in terms of electrochemical reactions between common SiO2 defects, and specific defect energy levels are assigned to the dominant transitions in the I-V response. The overshoot response in the LRS is consistent with TAT through either the Eγ' oxygen vacancy or the hydrogen bridge defect, both of which are reported to have an effective bandgap of 1.7 eV. The SET threshold at ~2.5V is modeled as hydrogen release from the (Si-H)2 defect to generate the hydrogen bridge, and the RESET transition is modeled as an electrochemical reaction that re-forms (SiH)2. The results provide further insights into charge transport and help identify potential switching mechanisms in SiOx-based unipolar resistive switching memory. [ABSTRACT FROM AUTHOR]

In this article, we demonstrate that Tully's fewest-switches surface hopping (FSSH) algorithm approximately obeys the mixed quantum-classical Liouville equation (QCLE), provided that several conditions are satisfied - some major conditions, and some minor. The major conditions are: (1) nuclei must be moving quickly with large momenta; (2) there cannot be explicit recoherences or interference effects between nuclear wave packets; (3) force-based decoherence must be added to the FSSH algorithm, and the trajectories can no longer rigorously be independent (though approximations for independent trajectories are possible). We furthermore expect that FSSH (with decoherence) will be most robust when nonadiabatic transitions in an adiabatic basis are dictated primarily by derivative couplings that are presumably localized to crossing regions, rather than by small but pervasive off-diagonal force matrix elements. In the end, our results emphasize the strengths of and possibilities for the FSSH algorithm when decoherence is included, while also demonstrating the limitations of the FSSH algorithm and its inherent inability to follow the QCLE exactly. [ABSTRACT FROM AUTHOR]

And, last but not least, Prudnikov et al. (article no. 2200700) introduce polyaniline-based organic memristive devices with volatile resistive switching and complex temporal behavior, which are capable of processing 4-bit sequences of data with reliable separation of states. Sparvoli et al. (article no. 2200591) simulated the behavior of neuronal membranes based on graphene oxide memristors and validated the operation of an RC circuit as a possible tool for the analysis of memristor devices. Thanks to this ability, such devices could be a valuable element for the realization of a reservoir computing system for the classification of handwritten digits from the MNIST dataset. [Extracted from the article]

Inhibition in task switching is inferred from n - 2 task repetition costs: slower response times and poorer accuracy for ABA task switching sequences compared to CBA sequences, thought to reflect the persisting inhibition of task A across an ABA sequence. Much work has examined the locus of this inhibition effect, with evidence that inhibition targets response selection processes. Consistent with this, fits of the diffusion model to n - 2 task repetition cost data have shown that the cost is reflected by lower estimates of drift rate, suggesting that inhibition impairs information processing efficiency during response selection. However, we have shown that the n - 2 task repetition cost is confounded with episodic retrieval effects which masquerade as inhibitory costs. The purpose of the current study was to conduct a comprehensive analysis of diffusion model fits to new data within a paradigm that controls for episodic interference. Across four experiments (total N = 191 ), we find evidence that the reduction of drift rate for n - 2 task repetition costs is only evident under conditions of episodic interference, and the cost is absent when this interference is controlled for. In addition, we also find evidence that episodic retrieval influences task preparation processes and response caution. These findings provide important constraints for theories of task switching that suggest inhibition selectively targets response selection processes. [ABSTRACT FROM AUTHOR]

A robust switched predictive control method is designed to deal with the multi-phase batch processes with the inevitable uncertainties, time-varying delay and unknown disturbances. Firstly, the output tracking errors are augmented into the state variables and then the improved robust switched predictive control law is established using the new augmented state variables. To this end, the novel switched system is built to represent the different phases of multi-phase batch processes. Secondly, making full use of the robust predictive control theory, Lyapunov function theory, switched system theory, linear matrix inequality (LMI) theory and mode-dependent average dwell time method, the sufficient conditions in terms of LMI constraints are derived to ensure that the switching system is asymptotically controllable and stable. During the process of derivation, based on the traditional performance indicators, the H-infinite performance index is introduced, so that the system in different phases can still operate stably under the uncertainty and external interference. The average dwell time and the control law gain of each phase are thus calculated by solving these LMI constrains. Ultimately, the simulation results on the injection molding process show that the proposed method can make the controlled system run stably. • Improved robust switched MPC is designed based on a new extended state space model. • The exponential stability conditions of the multi-phase batch process are given. • Mode-dependent average dwell time theory is adopted to solve the average dwell time. [ABSTRACT FROM AUTHOR]

This article presents an innovative technique for the black-box modeling of the conductive emissions of switching circuits from external observations. The proposed methodology relies on the robust and elegant theory of periodically switched linear systems, providing the user with a tool for the generation of frequency-domain augmented linear time-invariant equivalents. The obtained models offer both a remarkable accuracy for different supply conditions and a deep understanding of the inherent switching mechanisms of this class of devices. The proposed framework also enables the derivation of a simplified enhanced Norton representation which outperforms the classical state-of-the-art models based on linear time-invariant approximations. Model parameters are computed via a blind procedure based only on two measurements. The feasibility and strength of the proposed approach are demonstrated on a dc–dc boost power converter and on a dc electrical motor via the prediction of their conducted disturbances. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the leader-following bipartite consensus problem of multiple uncertain Euler-Lagrange (EL) systems over signed switching networks. We first extend the distributed observer for a linear leader system over signed communication networks from the static case to the jointly connected switching case. Based on such a distributed observer and the certainty equivalence principle, we further show that, under the assumptions that the signed switching network is structurally balanced and jointly connected, the leader-following bipartite consensus problem of multiple uncertain EL systems over signed switching networks is solvable by a class of distributed adaptive control law. Our result will then be applied to the leader-following bipartite consensus problem of a group of two-link robot manipulators. [ABSTRACT FROM AUTHOR]

The kinetic approach adapted to describe charge transmission in molecular junctions, is used for the analysis of the photocurrent under conditions of moderate light intensity of the photochromic molecule. In the framework of the HOMO-LUMO model for the single electron molecular states, the analytic expressions describing the temporary behavior of the transient and steady state sequential (hopping) as well as direct (tunnel) current components have been derived. The conditions at which the current components achieve their maximal values are indicated. It is shown that if the rates of charge transmission in the unbiased molecular diode are much lower than the intramolecular singlet-singlet excitation/de-excitation rate, and the threefold degenerated triplet excited state of the molecule behaves like a trap blocking the charge transmission, a possibility of a large peak-like transient switch-on photocurrent arises. [ABSTRACT FROM AUTHOR]

The growing resistive switching database is accompanied by many detailed mechanisms which often are pure hypotheses. Some of these suggested models can be verified by checking their predictions with the benchmarks of future memory cells. The valence change memory model assumes that the different resistances in ON and OFF states are made by changing the defect density profiles in a sheet near one working electrode during switching. The resulting different READ current densities in ON and OFF states were calculated by using an appropriate simulation model with variation of several important defect and material parameters of the metal/insulator (oxide)/metal thin film stack such as defect density and its profile change in density and thickness, height of the interface barrier, dielectric permittivity, applied voltage. The results were compared to the benchmarks and some memory windows of the varied parameters can be defined: The required ON state READ current density of 105 A/cm2 can only be achieved for barriers smaller than 0.7 eV and defect densities larger than 3 × 1020 cm-3. The required current ratio between ON and OFF states of at least 10 requests defect density reduction of approximately an order of magnitude in a sheet of several nanometers near the working electrode. [ABSTRACT FROM AUTHOR]

Within the framework of multiagent systems, relative information can be directly acquired by vehicle-mounted sensors and the relative information constraints inevitably occur due to limited sensing capabilities. This paper investigates observer-based consensus of nonlinear multiagent systems subject to relative state estimate constraints. Each agent’s state is constructed via a state observer, and the relative state estimate is assumed to be confined into a hypercube. In virtue of the edge Laplacian, the consensus problem of nonlinear multiagent systems under this constraint is converted into the stabilization problem of edge dynamics operating on the constrained set. Observer-based intermittent protocol and adaptive protocol are, respectively, designed for achieving consensus. A convergence analysis is provided with the help of state saturation theory, switched system theory and adaptive theory. Finally, the results on consensus with relate state estimate constraints are applied into the consensus problem while preserving the connectedness, and are validated by a simulation example. [ABSTRACT FROM AUTHOR]

In this paper, a novel quasi-resonant flyback converter that mainly comprises two modules of flyback converters is proposed. A relay is connected in series to the input terminals of two transformers, and the transformer input structure is adjusted according to the input voltage to improve the conversion efficiency. In addition, a novel frequency-limiting quasi-resonant control strategy for solving the limitations of the conventional quasi-resonant control strategies is proposed, wherein the switching frequency is increased under light load conditions. Here, the current-mode pulsewidth modulation IC is used as the core controller. The operating principle and design parameters of the converter are analyzed and discussed in detail. The experimental results prove the feasibility of the proposed circuit. [ABSTRACT FROM AUTHOR]