Principle Of Stability Research Articles

Monotonicity and discretization of Hammerstein integrodifference equations

<p style='text-indent:20px;'>The paper provides sufficient conditions for monotonicity, subhomogeneity and concavity of vector-valued Hammerstein integral operators over compact domains, as well as for the persistence of these properties under numerical discretizations of degenerate kernel type. This has immediate consequences on the dynamics of Hammerstein integrodifference equations and allows to deduce a local-global stability principle.</p>

The Global Peace Mandate of the United Nations Security Council, Conflict Management and the Israeli-Palestinian Question

The United Nations global conflict management strategy is based on certain fundamental assumptions that require serious re-examination in the twenty-first century. This study is focused on the United Nations Security Council, its global peace maintenance responsibility mandated by the United Nations Charter and the protracted Israeli-Palestinian conflict. The doctrinal approach was employed for this study. This is with aim to assess the long-standing violence between Israel and Palestine and a possible way of effective management and possible resolution, which is the sole responsibility of the United Nations Security Council. The study shed more light on the role of the Security Council, its efforts and its challenges that are hampering warring nations from settling their disputes. The study concluded that, although the United Nations Security Council has played vital roles in instituting global peace, which is the fundamental principle of macroeconomic stability, the reforms of the Council is at the top of the most pressing global political issues facing the international community. Therefore, among the recommendations of this study is that, the reformation of the Council to mirror the present globalized world political order is of utmost significance in order to provide room for effective regional or continental representation, just as a representative government is well suited for a federating country. This would enable effective representation via regional or continental powers creating a platform for feasibly effective conflict management and possible resolution of interstate conflicts.

Impact of public financial policy on implementing the principle of stability

The paper addresses the issues of implementing the principle of stability, when the state, changing the rates of taxes, fees and other mandatory payments, should not only focus on replenishing resources to fulfil its obligations to society, but also stimulate economic activity. Discretion has been researched into regarding the implementation of public financial policy in the context of applying the principle of stability, which could be carried out taking into account the target interpretation of the system of legal regulators, when the law enforcement body chooses the regulator whose application will lead to a more reasonable and fair result. It is about the subsidiary application of independent regulators.
 The author focuses on the fact that from the standpoint of the principle of the rule of law and in view of the formation of supranational law, including financial, consideration of principles and morality is the primary step before applying the provisions of the law. It is not legitimate to form the practice of law enforcement against the fundamental principles of law. The following levels of principles have been defined: 1) supranational; 2) national. Issues have been addressed in the paper that it is strategically correct, if the rule of law does not correspond to the principle, then it is necessary to recognize it as illegal and apply the principles, simultaneously changing the rules of the law. It has been proposed that when adopting legislation on normative acts, it is necessary to shift the hierarchy to the principle from the norm-law. The author focuses on the fact that, in order to achieve national and public interests, the Verkhovna Rada of Ukraine has the right to change the provisions of the law, to adopt new laws that change the legal regulation, contradicting the previous legal norms. Thus, the provisions of previous laws are automatically terminated.
 The procedural discretion has been identified as related to a fairly wide scope of the court’s powers in carrying out procedural activities for the purpose of resolving the pending dispute. Both general principles of law and relevant procedural principles, as well as principles of the specialized field of material law, are taken into account. One of the key issues remains the promotion of trust in public authorities, in particular, on the part of the participants in the judicial process. The limiting factors of discretion have been addressed in the paper as legal regulations and factual circumstances of the case. Establishing the factual circumstances of the case is carried out in combination with the evaluation and interpretation of legal facts or structures, justification of the legal position.

Legal positions of the Constitutional Court of Ukraine: analysis of legal doctrine

It is indicated that constitutional control is defined as one of the main elements of legal protection of the constitution. The difficulty of defining its nature is expressed in the ambiguity of approaches among scientists regarding the analysis of this concept. The science of constitutional law distinguishes two approaches to the understanding of constitutional control – broad and narrow. The authors note that, summarizing the specified formulations, it can be argued that they reflect only one of the aspects of understanding constitutional control – from the point of view of the functional approach. That is, to a greater extent,the emphasis is placed on checking the constitutionality of laws and other acts. In the understanding of the authors, supporters of the functional approach, constitutional control is only constitutional regulatory control.The research presented in the work gives grounds for the conclusion that the issue of clarifying the legal nature of the legal positions of the Constitutional Court of Ukraine is ambiguous and has not yet been resolved. This is connected, first of all, with a complex and multifaceted understanding of the role, status and place of the body of constitutional jurisdiction in the system of state authorities. The absence of a legislative definition of this concept does not contribute to clarifying the nature of the Court’s legal positions. Despite this, the term is actively used both by the Court in its decisions and by the scientific community in order to reflect the arguments that determine the position of the Constitutional Court of Ukraine on law enforcementissues. Legal positions also acquire normative mandatory content, which follows from the form of expression in which they are reflected – acts of the Constitutional Court of Ukraine. At the same time, legal positions can be expressed both in the motivating and in the resolutive part of the decision. The need to ensure the immutability of the Court’s legal positions is a continuation of the principle of legal certainty and stability of the Constitution as the Basic Law of Ukraine. However, the question of the possibility of revision of legal positions by the Constitutional Court becomes more urgent in connection with the partial politicalinvolvement of the Court in the previous years of its activity, which requires revision of certain positions due to changes in the socio-political structure of the state. The outlined question, along with others, is definitely an additional subject of a separate scientific study.

Three-Stage-Impulse Control of Memristor-Based Chen Hyper-Chaotic System

In this paper, on the basis of the three-dimensional Chen system, a smooth continuous nonlinear flux-controlled memristor model is used as the positive feedback term of this system, a hyper-chaotic circuit system is successfully constructed, and a simulated equivalent circuit is built for simulation using Multisim software, which agrees with the numerical simulation results by comparison. Meanwhile, a new impulsive control mode called the three-stage-impulse is put forward. It is a cyclic system with three components: continuous inputs are exerted in the first and third parts of the cycle while giving no input in the second part of the cycle, an impulse is exerted at the end of each continuous subsystem, the controller is simple in structure and effective in stabilizing most existing nonlinear systems. The Chen hyper-chaotic system will be controlled based on the three-stage-impulse control method combined with the Lyapunov stability principle. At the end of this paper, we have employed and simulated a numerical example; the experimental results show that the controller is effective for controlling and stabilizing the newly designed hyper-chaotic system.

Finite-Time Control of High-Speed Train With Guaranteed Steady-State and Transient Performance

With considering the inevitable factors of input nonlinearity, aerodynamic resistance, in-train force, external disturbance and unknown actuator failures, this paper investigates the position/velocity finite-time tracking control problem of high-speed train (HST) to improve the steady-state (tracking accuracy) and transient performance (overshoot and settling time) of the traction/braking control system. Since the traction/braking control system of HST requires rapid reaction speed to ensure the safe and reliable operation, an integer-order finite-time controller (IO-FTC) is developed firstly by utilizing finite-time control theory to improve the system transient performance. On the basis of ensuring the system transient performance, a fractional-order finite-time controller (FO-FTC) is designed by using the fractional stability principle and fractional integral to further improve the system steady-state performance and its robustness and anti-jamming capability. It should be noted that both IO-FTC and FO-FTC are essentially independent of the system model and can produce proper traction/braking force with only the actual and desired position/velocity of the leading vehicle. And the settling time of the system can be adjusted through the selection of different control parameters. The feasibility and effectiveness of the designed controllers are verified by theoretical analysis and simulation studies. And the developed methods are compared with the PID controller. Simulation results make it clear that the proposed methods are superior to PID.

Interactive responses of root and shoot of camphor tree (Cinnamomum camphora L.) to asymmetric disturbance treatments.

Plant root and shoot growth are closely interrelated, though the connotation of root-shoot balance should not be limited to their connectivity in biomass and physiological indicators. Their directional distribution of mass in architecture and the resulting root-shoot interactions are the keys to understanding the dynamic balance of the below- and above-ground organs related to tree anchorage. This study focuses on the 4-year-old camphor tree (Cinnamomum camphora L.) as a system to observe the biomass distribution in response to the asymmetric disturbance treatments of biased root (BRT), inclined trunk (ITT), and half-crown (HCT) in a controlled cultivation experiment using the minirhizotron technique. We found an inverse relationship of biomass distribution of crowns to roots in BRT and opposite asymmetries of roots with crowns in response to the ITT and HCT treatments. We also observed higher net photosynthesis rate (Pn ), water use efficiency, and chlorophyll content in the leaves on the side opposite the lean in ITT, and higher Pn , transpiration rate, and chlorophyll content on the root-bias side in BRT, which is consistent with the nutrient allocation strategies of allocating nutrients across plant organs in an optimal way to obtain 'functional equilibrium' and adapt to the stressed environment. Furthermore, the asymmetrical growth transformation of first-level branch length from the root-bias side to the opposite side in BRT, and a similar transformation of root length from the crown-bias side to the opposite side in HCT, imbues further theoretical support of the nutrient allocation strategy and the biomechanical stability principle, respectively. In summary, this study is the first to identify opposite interaction between below- and above-ground biomass distributions of the camphor tree. The findings enrich the connotation of root-shoot interactions and help to realize root design for the silviculture management of urban forests.

Adaptive neural network–based trajectory tracking non-affine control of hovercraft with double-loop constraint performance

This study investigates the design of a trajectory tracking constraint control method for hovercraft non-affine formulations via neural network approximation. The tracking scheme comprises an outer closed-loop of attitude and an inner closed-loop of velocity (double-loop). First, a performance function is devised to constrain the attitude errors and then a transformed error function is introduced to simplify it into an equivalent unconstrained control system. Next, an improved asymmetric integral barrier Lyapunov function is designed to address asymmetric velocity constraint problems, which can guarantee the safe turning motion or performance required at high speed. Furthermore, neural networks are employed to estimate the unknown terms of each subsystem, which solve system uncertainties and non-affine dynamics problems. The double closed-loop control system is ultimately uniformly bounded by utilizing the Lyapunov stability principle. Finally, simulation results are presented to verify the tracking performance and effectiveness of the proposed control strategy.

Weak-strong uniqueness for volume-preserving mean curvature flow

In this note, we derive a stability and weak-strong uniqueness principle for volume-preserving mean curvature flow. The proof is based on a new notion of volume-preserving gradient flow calibrations, which is a natural extension of the concept in the case without volume preservation recently introduced by Fischer, Hensel, Laux and Simon (2021). The first main result shows that any strong solution with certain regularity is calibrated. The second main result consists of a stability estimate in terms of a relative entropy, which is valid in the class of distributional solutions to volume-preserving mean curvature flow.

Reticular chemistry for the rational design of mechanically robust mesoporous merged-net metal-organic frameworks

Reticular chemistry for the rational design of mechanically robust mesoporous merged-net metal-organic frameworks

Adaptive Chattering-Free PID Sliding Mode Control for Tracking Problem of Uncertain Dynamical Systems

Aiming at the trajectory tracking problem with unknown uncertainties, a novel controller composed of proportional-integral-differential sliding mode surface (PIDSM) and variable gain hyperbolic reaching law is proposed. A PID-type sliding mode surface with an inverse hyperbolic integral terminal sliding mode term is proposed, which has the advantages of global convergence of integral sliding mode (ISM) and finite time convergence of terminal sliding mode (TSM), and the control effect is significantly improved. Then, a variable gain hyperbolic approach law is proposed to solve the sliding mode approaching velocity problem. The variable gain term can guarantee different approaching velocities at different distances from the sliding mode surface, and the chattering problem is eliminated by using a hyperbolic function instead of the switching function. The redesign of the sliding mode surface and the reaching law ensures the robustness and tracking accuracy of the uncertain system. Adaptive estimation can compensate for uncertain disturbance terms in nonlinear systems, and the combination with sliding mode control further improves the tracking accuracy and robustness of the system. Finally, the Lyapunov stability principle is used for stability analysis, and the simulation study verifies that the proposed control scheme has the advantages of fast response, strong robustness, and high tracking accuracy.

Benchmarking Dynamic Balancing Controllers for Humanoid Robots

This paper presents a comparison study of three control design approaches for humanoid balancing based on the Center of Mass (CoM) stabilization and body posture adjustment. The comparison was carried out under controlled circumstances allowing other researchers to replicate and compare our results with their own. The feedback control from state space design is based on simple models and provides sufficient robustness to control complex and high Degrees of Freedom (DoFs) systems, such as humanoids. The implemented strategies allow compliant behavior of the robot in reaction to impulsive or periodical disturbances, resulting in a smooth and human-like response while considering constraints. In this respect, we implemented two balancing strategies to compensate for the CoM deviation. The first one uses the robot’s capture point as a stability principle and the second one uses the Force/Torque sensors at the ankles to define a CoM reference that stabilizes the robot. In addition, was implemented a third strategy based on upper body orientation to absorb external disturbances and counterbalance them. Even though the balancing strategies are implemented independently, they can be merged to further increase balancing performance. The proposed strategies were previously applied on different humanoid bipedal platforms, however, their performance could not be properly benchmarked before. With this concern, this paper focuses on benchmarking in controlled scenarios to help the community in comparing different balance techniques. The key performance indicators (KPIs) used in our comparison are the CoM deviation, the settling time, the maximum measured orientation, passive gait measure, measured ankles torques, and reconstructed Center of Pressure (CoP). The benchmarking experiments were carried out in simulations and using the facility at Istituto Italiano di Tecnologia on the REEM-C humanoid robot provided by PAL robotics inside the EU H2020 project EUROBENCH framework.

Defending Art. 51 of theCode: Comments on Smith & al. (2022)

AbstractSmith & al. (2022), Hammer & Thiele (2021), and some other authors recently discussed and proposed dramatic changes to theInternational Code of Nomenclature of algae, fungi, and plants(ICN) aimed at the provisions allowing rejection and replacement of valid and legitimate names that reflect the “colonial and imperialist power” or may be considered, at least by some experts and users, as “culturally offensive or inappropriate” because of several broadly and vaguely formulated reasons, such as names considered to be “derogatory or insulting to a person or group of people”, those honoring “a person that the taxonomic community agrees should not be honoured”, and even any name that “otherwise causes deep offense”. These proposals and their possible outcomes were analyzed and criticized in my article (Mosyakin, 2022), which was, in turn, criticized in a recent article by Smith & al. (2022). In the present note I respond to that criticism, discuss additional cases of possible “culturally offensive or inappropriate” names, and provide additional evidence of possible (and, in my opinion, highly probable) confrontational and disruptive outcomes in case if the proposals to reject “culturally offensive or inappropriate” names are accepted and incorporated into theICN. I appeal to the international community of taxonomists to reject such proposals, to protect the fundamental Preamble 1 and Art. 51 of theICN, to protect the scientific freedom and principles of nomenclatural stability and political neutrality, and to protect our science from politically motivated decisions. The Pandora's Box of anticipated fights for or against “culturally offensive and inappropriate names” should remain firmly closed. Scientists in general and plant taxonomists in our case should firmly stand for the common values of scientific freedom, mutual understanding and respect, tolerance, reconciliation, a bold, open‐minded and honest view of history (including history of taxonomy), and, specifically, the principle of neutrality of biological nomenclature well expressed in Art. 51 of theICN. Essentially the same provisions in earlier versions of theCodeor other earlier rules of botanical nomenclature served well the generations of taxonomists and users of taxonomic information, preventing unnecessary conflicts between people and peoples over names of organisms, which someone sometime somehow may or may not consider “culturally offensive or inappropriate”. Preamble 1 and Art. 51 of theICNare crucial tools for maintaining nomenclatural stability, civility, and tolerance in our diverse, complicated and, unfortunately, not so peaceful present‐day world, and especially in our science of biological taxonomy reflecting the amazing diversity of the living world of our planet.

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.

Discovering design principles of collagen molecular stability using a genetic algorithm, deep learning, and experimental validation

Collagen is the most abundant structural protein in humans, providing crucial mechanical properties, including high strength and toughness, in tissues. Collagen-based biomaterials are, therefore, used for tissue repair and regeneration. Utilizing collagen effectively during materials processing ex vivo and subsequent function invivo requires stability over wide temperature ranges to avoid denaturation and loss of structure, measured as melting temperature (Tm). Although significant research has been conducted on understanding how collagen primary amino acid sequences correspond to Tm values, a robust framework to facilitate the design of collagen sequences with specific Tm remains a challenge. Here, we develop a general model using a genetic algorithm within a deep learning framework to design collagen sequences with specific Tm values. We report 1,000 de novo collagen sequences, and we show that we can efficiently use this model to generate collagen sequences and verify their Tm values using both experimental and computational methods. We find that the model accurately predicts Tm values within a few degrees centigrade. Further, using this model, we conduct a high-throughput study to identify the most frequently occurring collagen triplets that can be directly incorporated into collagen. We further discovered that the number of hydrogen bonds within collagen calculated with molecular dynamics (MD) is directly correlated to the experimental measurement of triple-helical quality. Ultimately, we see this work as a critical step to helping researchers develop collagen sequences with specific Tm values for intended materials manufacturing methods and biomedical applications, realizing a mechanistic materials by design paradigm.

Automatic Control of Food Machinery Based on Neural Network and Computational Torque Compounding

In order to improve the effect of automatic control of food machinery, this paper combines neural network and computational torque compounding to study the automatic control system of food machinery to improve the effect of automatic control of food machinery. Moreover, this paper studies the problem of strong time-varying nonlinear friction disturbance in the servo motion system, and analyzes the friction nonlinearity at low speed and commutation motion of the system. In addition, this paper introduces the application requirements for the nonlinear friction compensation control method, and proves that the designed controller can maintain the stability of the system under the condition of strong nonlinear time-varying friction through the Lyapunov stability principle. The experimental study shows that the control strategy given in this paper can not only effectively improve the tracking speed of the joints, but also effectively alleviate the later tremor, and the automatic control effect of food machinery based on neural network and computational torque compounding has certain effects.

Vacancy Hardening and Ordering in Rhenium Tungsten Carbides

Vacancies generally reduce the number of chemical bonds and hence cause structural softening. It is puzzling, however, that substoichiometric Re0.5W0.5C0.4 with 60% carbon vacancies was identified as a superhard material. Here, we report the underlying mechanism responsible for such anomalous vacancy-induced hardening in the Re0.5W0.5C1–x system via first-principles calculations. The shear stiffness and hardness increase consistently with rising carbon vacancy concentration in Re0.5W0.5C1–x and reach the maximum at about x = 40%. Such an unexpected hardening phenomenon originates from a gradual relief of the shear-unstable dd bonding and unfavorable pd antibonding interactions owing to the formation of C-vacancies. We further predict that the simultaneous ordered vacancies of W and C atoms can produce a cubic crystalline Re2/3W1/3C that is isomorphic with the NbO type. The calculations on vibrational, mechanical, and electronic properties reveal that this phase has considerable structural stability and is a hard metallic material. This work not only elucidates the intriguing mechanism responsible for the vacancy hardening in this class of systems but also provides a new principle for the structural stability of other transition-metal compounds.

Seismic Stability from Low Ductility to Enhanced Resilience

AbstractThe fundamental basis for seismic stability is clear – during an earthquake, a building must be capable of carrying gravity loads while developing large inelastic deformations and associated lateral displacements. However, structural design to achieve this performance objective is complex and depends upon multiple system parameters. In current seismic provisions, the global destabilizing effects of gravity are typically considered with simplistic models that may not properly address the actual inelastic stability response of building structures. Building systems with high ductility are used extensively in high‐seismic regions, but in moderate‐seismic regions, systems with low ductility are ubiquitous. The inelastic responses of low‐ductility and high‐ductility systems are starkly different, and life safety must be ensured across this wide variation in behavior. This paper will discuss foundational seismic stability principles and explore the range of inelastic response that is associated with conventional seismic systems and novel next‐generation systems. Results from large‐scale component tests, full‐scale frame tests and numerical earthquake simulations will be used to demonstrate several important concepts: (1) high‐ductility response is an insufficient, and not always necessary, condition for seismic stability; (2) the most critical parameter for seismic stability is persistent secondary stiffness; (3) emerging technologies like recentering, which limit damage, are promising solutions for enhanced seismic resilience.

A novel synchronization control with index adjuster for stochastic neural networks via trace similarity

Based on the stability of the error system, we focus on the synchronization control of Stochastic Neural Networks (SNNs) with Time-Varying Delays (TVD). In order to observe the effect of the slave system following the drive system, we carry out the output result analysis of networks based on logic framework for the drive-follow systems. The constructive method and extremum theory are utilized to prove that the sample traces are similar to the state traces of the systems. For achieving the efficient control of the error system, the gain matrix of the controller with index regulator is designed to adjust the intensity of the parameters. Through one contrast analysis, the proposed control method is superior to the control approach given by comparative literature. Employing rigorous derivation, the exponential synchronous conditions are obtained based on trace similarity and the Lyapunov stability principle. In particular, one numerical example with three neurons fully validates the obtained results.

Are mining companies mature for mine closure? An approach for evaluating preparedness

Evaluating how well a mining company is prepared to close an operating mine can help in managing the risks of not achieving closure goals and intended future site conditions. Considering international best practices recommendations, we developed and tested a procedure to evaluate, during the operational phase, the preparedness of companies to close a mine. Based on the principles of physical stability, chemical stability, socioeconomic transition, and post-mining land use, a weighted checklist containing 69 best practice statements was tested in three operating metal mines in Northeastern Brazil. The best practice statements and their respective weights were submitted to a 12-member expert group. The practices are organized in four assessment areas: (i) mine closure documents, (ii) physical and chemical stability, (iii) costs and financial provisioning, and (iv) community engagement and social transition. In applying the tool, evidence is collected by document review, interviews and site inspections, and evaluated using professional judgement to determine a level of achievement for each group of practices. A preparedness index is then calculated and a preparedness level is obtained. All field-tested mines ranked high for cost and financial provisioning, possibly reflecting they are publicly-owned companies, but ranked in the medium range for the three other assessment areas, indicating a risk of negative legacy. Their preparedness for closure should be a matter of concern for investors, regulators and communities.