Internal Delay Research Articles

Global existence and below up of logarithmic non linear vscoelastic wave equation

In this paper, we consider the following nonlinear vscoelastic wave equations with internal constant delay term. Using the semigroup theory we proved the local existence , the global existence establish by the potential well method, and, we obtain the asymptotic behavior by applying the multiplier method.

A lightweight reversible multi-mode physical unclonable function

Physical Unclonable Function (PUF), a hardware security primitive capable of generating unique fingerprints for chips, is crucial for Internet of Things (IoT) security. However, substantial hardware overhead, low reliability, and high power consumption have hindered the broad application of PUFs in lightweight IoT devices. This paper proposes a solution by leveraging the reversible logic paradigm in PUF design. Specifically, a Multi-Mode (M2) PUF is introduced and is based on configurable ring oscillators and transient effect rings. By configuring signal paths and internal delays, the M2 PUF efficiently generates numerous Challenge-Response Pairs (CRPs) with minimal hardware resources. Implemented on Xilinx Spartan-6 and Xilinx Virtex-7 FPGA platforms, it requires only 1.6 % of the hardware resources to generate a 1-bit response, significantly lower than existing state-of-the-art PUF solutions. The performance metrics for uniqueness, average native reliability, and reliability under different voltage conditions are impressive, registering at 48.23 %, 98.44 %, and 96.08 %, respectively. This structure represents an ideal solution for lightweight PUF design.

Well-posedness and exponential stability of piezoelectric beam with thermal effect and boundary or internal distributed delay

In this work, we focus on a one-dimensional initial-boundary value problem of a thermoelastic piezoelectric beam in the presence of magnetic effects with distributed delay acting in the mechanical equation. The well-posedness of the system is initially demonstrated by applying semigroup theory (Hille-Yosida theorem). Also, based on the construction of a Lyapunov functional, which is equivalent to the energy functional of the problem through multiplier techniques, we show that a unique dissipation through frictional damping is strong enough to ensure exponential stabilization of the model. Next, the results are compared to those of the electrostatic or quasi-static approaches. Moreover, we consider the fully dynamic and electrostatic or quasi-static piezoelectric beams with thermal effects, boundary feedback controllers and boundary distributed delays and using the multipliers technique, we establish an exponential stability result of the solution. Our results are related to the distributed delay weights. Finally, we give some numerical tests to illustrate the theoretical result.

Exponential Stability of a Kirchhoff Plate Equation with Structural Damping and Internal Time Delay

In this manuscript, we investigate the exponential stability of a Kirchhoff plate equation with free boundary conditions in a bounded domain of R2. First, we consider the case where the model is subjected only to structural damping and, using the energy method, we prove the exponential decay of the energy associated with this model. Second, we consider the case where structural damping with a linear internal time delay term is applied, and we use the same technique to derive the exponential stability of the new model. Finally, we examine the scenario where the model is governed by structural damping with an added fractional time delay term and, by constructing an appropriate Lyapunov function, we show that the energy associated with the system is exponentially stable. This work improves upon prior results concerning the Kirchhoff plate equation with frictional damping, where exponential stability could not be achieved.

An experimental and numerical investigation of the thermal performance of phase change materials in different triple-glazed window configurations

Phase Change Materials (PCM) may be excellent thermal insulation due to their poor conductivity and high heat capacity. Researchers are adding PCM to windows. This integration modifies internal surface temperatures and delays peak temperatures to improve indoor thermal comfort. This work investigates experimentally and numerically the impact of the different filling materials in four Triple Glazed Windows (TGW) configurations in an Iraqi environment: the first window filled two cavities with air (standard); the second window has one cavity filled with a PCM and the other with air; the third window has blinders with various tilt angles in one cavity and PCM in the other cavity; and in the fourth window, both cavities are filled with PCM. Numerically utilizing Computational Fluid Dynamics to evaluate the thermal performance of TGW. In August, when the solar radiation was at its maximum (623 W/m2), the results showed that the peak interior surface temperature dropped by 4.51, 13.28 and 11.53 % in the TGW configurations (PCM-air), (blinder-PCM), and (PCM-PCM), compared to the standard TGW. The fourth window increased the time lag by 2 h, effectively shifting the load and in the third window, the best tilt angle blinder is 45°

Orientation-resolved attosecond photoionization delays in the N2O molecule

We present a thorough theoretical and experimental investigation of photoionization time delays in the N2O molecule. Our theory provides actual XUV+IR time-resolved photoelectron spectra as measured in real reconstruction of attosecond beating by interference of two-photon transitions (RABBIT) experiments. This requires not only accounting for the interaction between the XUV field and the neutral molecule, but also between the IR field and the ejected electron, which is only possible through explicit evaluation of a large number of dipole couplings between molecular electronic continuum states. To compare with the results of these calculations we have performed RABBIT experiments in which the ejected electron and the resulting ionic fragments are measured in coincidence, thus allowing us to obtain photoionization delays for a particular orientation of the molecule with respect to the polarization of the XUV and IR fields. We have found very good agreement between calculated and measured RABBIT spectra for both nondissociative and dissociative ionization channels. In particular, we unambiguously show a photoionization delay of about 60 as in the vicinity of a well-known shape resonance of N2O in the nondissociative ionization channel. More importantly, we show a dramatic effect of the IR field in the orientation-resolved ionization delays in the whole photon energy range investigated in this paper (18–40 eV), even at the level of ionization delays (i.e., delays referred to an internal reference delay) where the effect of the IR field is generally assumed to cancel out. Finally, we explicitly show that the problem of spectral congestion inherent to most molecular systems, which usually prevents extraction of photoionization delays, is substantially alleviated by resolving the molecular orientation or, ideally, by resolving both the molecular orientation and the electron emission angle, where access to perfectly isolated ionization channels is possible at specific angles. Published by the American Physical Society 2024

Consensus of Euler–Lagrange Agents With Internal Model Disturbance Rejection and Interconnection Delays

Consensus of Euler–Lagrange Agents With Internal Model Disturbance Rejection and Interconnection Delays

Experimental Evaluation of a Granular Damping Element.

Due to their advantages-longer internal force delay compared to bulk materials, resistance to harsh conditions, damping of a wide frequency spectrum, insensitivity to ambient temperature, high reliability and low cost-granular materials are seen as an opportunity for the development of high-performance, lightweight vibration-damping elements (particle dampers). The performance of particle dampers is affected by numerous parameters, such as the base material, the size of the granules, the flowability, the initial prestress, etc. In this work, a series of experiments were performed on specimens with different combinations of influencing parameters. Energy-based design parameters were used to describe the overall vibration-damping performance. The results provided information for a deeper understanding of the dissipation mechanisms and their mutual correlation, as well as the influence of different parameters (base material, granule size and flowability) on the overall damping performance. A comparison of the performance of particle dampers with carbon steel and polyoxymethylene granules and conventional rubber dampers is given. The results show that the damping performance of particle dampers can be up to 4 times higher compared to conventional bulk material-based rubber dampers, even though rubber as a material has better vibration-damping properties than the two granular materials in particle dampers. However, when additional design features such as mass and stiffness are introduced, the results show that the overall performance of particle dampers with polyoxymethylene granules can be up to 3 times higher compared to particle dampers with carbon steel granules and conventional bulk material-based rubber dampers.

General stability of a triple layer beam with time-varying delay and weak internal damping

Analyzing a triple layer Rao–Nakra beam model which has time-dependent weight function and delay, weak internal damping, with thermal dissipation elements, is our focus. Heat conduction from Fourier’s law was adopted to regulate the thermal dissipation. It is known that when the three equations of the Rao–Nakra beam is directly and globally damped, an exponential stability is achieved. Weak internal damping leads to prolonged resonance, extended vibrational amplitudes and periods, as well as delayed energy dissipation. In this work we will rigorously demonstrate that despite weak internal damping and delay term in the bottom layer’s equation, we can obtain a general stability for the Rao–Nakra beam model. As a result, exponential and polynomial decay can be deduced as particular instances.

Development and Implementation of an FPGA-Embedded Multimedia Remote Monitoring System for Information Technology Server Room Management

Conventional data acquisition systems face challenges in achieving high acquisition speeds and rapid storage of large data volumes using microcontrollers. In contrast, field-programmable gate arrays (FPGAs) offer numerous advantages, including high clock frequencies, minimal internal delays, fast operational speeds, abundant internal RAM resources, and simplified control of complex peripheral circuits. This study presents the design of an FPGA-based multimedia remote monitoring system for information technology server rooms. The proposed system utilizes an FPGA as the primary controller and incorporates environmental sensors, electrical energy sensors, carbon monoxide sensors, smoke sensors, and A/D converter modules to monitor multiple locations within the server room. Simultaneously, the FPGA transmits the collected data from each monitoring point via a serial port to an LCD serial screen for display. An alarm is triggered if any environmental anomalies are detected, indicating abnormal statuses. Additionally, the system employs the fast Fourier transform algorithm and butterfly operations to derive voltage and current AC quantities, while utilizing relative temperature differences to identify equipment faults within the server room. The system is evaluated in terms of functionality, user-friendliness, and reliability. Experimental results demonstrate that all performance measures align with expectations, fulfilling the initial design objectives and highlighting the potential applicability and relevance of FPGA technology in the monitoring field. In addition, a comparison between FPGA and traditional microcontroller systems is performed, showcasing the superior processing speed and performance of the FPGA-based system. This comparative analysis further validates the advantages of using FPGA technology in high-speed data acquisition and monitoring applications.

Abstract WP44: Assessing Timely Care of WI's Critical Access Hospitals Acute Stroke Patients With a Speed and Efficiency Task Force

Introduction: Data indicates that rural residents are at 30% higher risk of stroke. 2 Thirty percent of Wisconsin’s (WI) residents live in a rural area and are more often served by smaller, critical access hospitals (CAH). WI Coverdell Stroke Program (Coverdell) data entry into Get With The Guidelines-Stroke® (GWTG) for 2022 shows 22.3% of stroke patient’s transfer from a spoke, often CAH, to a larger tertiary or hub hospital. To assist Coverdell participating (CAH) in timely care of acute stroke patients, Coverdell, American Heart Association® (AHA), and 32 CAH’s partnered to form a Speed and Efficiency Taskforce (TF). Methods: An agreed upon charter, framework and data goals were established in May 2022. Metrics of EMS pre-notification, arrival to CT, and door to needle (DTN) times were regularly reviewed. Evaluation of patients arriving within 4.5 hours of last known well (LKW), median DTN, and percent DTN < 60 minutes were analyzed in two arrival windows. Hypothesized differences when comparing arrival windows of 0700-1900 and 1901-0659 were that the 1901-0659 window would have extended treatment times due to lack of 24/7 CT coverage and LKW not validated from others. Results: Data analysis for 2022. N=179 • Arrival to CT: 10 minutes faster in 1901-0659 window • Median DTN: 3 minutes faster in 0700-1900 window (71 vs 74 minutes respectively) • % DTN within 60 minutes: 12% higher compliance in 0700-1900 window Conclusions: Coverdell CAH’s are initiating the CT in a timely manner. Times are lower for arrivals between 1901-0659, ruling out delays due to CT tech non-availability. Delays in DTN treatment times within 60 minutes of arrival are more significant in the 1901-0659 arrival timeframe. The potential causes are a delay in telestroke consult with decision to treat, internal hospital delays in mixing and delivering thrombolytics, CT availability, and family/significant others present. Further research regarding arrival time affecting treatment need to be considered.

Synchronization in PLL Networks: Numerical Simulations Using Julia

Clock distribution systems are used in many applications requiring accurate time basis: integrated circuits, computer networks, satellite communications, and Global Position System (GPS). Trying to automatize the design of clock distribution systems, this work presents a general formulation considering the possible topologies and parameters, building a computational tool allowing to design and evaluate the performance of any case to be studied. The developed tool enables to simulate networks setting the number of nodes, internal node parameters, topology, perturbations, and signal propagation delays. The simulation results include response times, synchronization quality, and stability for all types of arrangements: mutually connected, chains, rings, stars, and mixed architectures.

Stabilization of a microbeam system with a boundary or internal distributed delay

In this paper, we consider the microbeam system with distributed delay term on the boundary or into the domain. In both cases, and thanks to a clever combination of spectral decomposition theory of Sz-Nagy-Foias [18] and frequency domain approach and under some additional and suitable assumptions, we prove the exponential stability of the total energy of our considered system.

Anti-lock braking control using an interval type-2 fuzzy neural network scheme for electric vehicles

Control precision and robustness can be regarded as essential challenges of slip ratio control because of the external uncertainties of road conditions and the internal delay response of braking actuators. In addition, it is difficult to obtain a trade-off between braking energy recovery efficiency and braking safety under some extreme braking conditions. To synchronously improve both slip ratio control and braking energy recovery efficiency for different road conditions, an anti-lock braking system (ABS) using a novel interval type-2 fuzzy neural network (IT2FNN) control scheme is proposed for electrohydraulic braking systems. The novel IT2FNN control scheme with five layers is designed to calculate the commanded braking torque. The membership function layer utilizes type-2 fuzzy sets to describe the slip ratio error degree, which enhances the scheme’s anti-interference ability, and the enhanced Karnik-Mendel (EKM) algorithm is used in the type-reduction layer to accelerate computation. Additionally, the network adjusts the parameters of the membership function and rules by decreasing the performance function value corresponding to the braking torque error to improve slip ratio control and enhance the self-adaptation capacity. Simulations showed that IT2FNN control can not only improve slip ratio control performance and decrease the braking torque error but also enhance the energy recovery efficiency of regenerative braking on different road surfaces.

A chemical reaction network implementation of a Maxwell demon.

We study an autonomous model of a Maxwell demon that works by rectifying thermal fluctuations of chemical reactions. It constitutes the chemical analog of a recently studied electronic demon. We characterize its scaling behavior in the macroscopic limit, its performances, and the impact of potential internal delays. We obtain analytical expressions for all quantities of interest: the generated reverse chemical current, the output power, the transduction efficiency, and correlation between the number of molecules. Due to a bound on the nonequilibrium response of its chemical reaction network, we find that, contrary to the electronic case, there is no way for the Maxwell demon to generate a finite output in the macroscopic limit. Finally, we analyze the information thermodynamics of the Maxwell demon from a bipartite perspective. In the limit of a fast demon, the information flow is obtained, its pattern in the state space is discussed, and the behavior of partial efficiencies related to the measurement and feedback processes is examined.

Novel Synchronization Criteria for Non-Dissipative Coupled Networks with Bounded Disturbances and Time-Varying Delays of Unidentified Bounds via Impulsive Sampling Control

The μ−synchronization issues of non-dissipative coupled networks with bounded disturbances and mixed delays are studied in this article. Different from existing works, three kinds of time delays, including internal delays, coupling delays, and impulsive sampling delays, have unidentified bounds and even evolve towards infinity over time, making the concerned network more practical. Considering μ−stability theory and impulse inequality techniques, a hybrid non-delayed and time-delayed impulsive controller including both current and historical state information is designed, and several novel sufficient conditions are derived to make nonlinear complex networks achieve μ−synchronization. Moreover, not only can the constriction of dissipative coupling conditions on network topology be relaxed, but also the restriction of various time delays on impulsive intervals can be weakened, which makes the theoretical achievements in this article more general than the previous achievements. Ultimately, numerical simulations confirm the effectiveness of our results.

Well-Posedness and Energy Decay Rates for a Timoshenko-Type System with Internal Time-Varying Delay in the Displacement

In this work, we consider a Timoshenko-type system in a bounded one-dimensional domain under Dirichlet conditions with time-varying delay and internal friction damping acting in the displacement. First, we show that the system is well-posed using semi-group theory. Then, under appropriate assumptions on the weights of the delay, the stability of system is obtained via a suitable Lyapunov functional.

Synchronization of multi-weighted complex networks with mixed variable delays and uncertainties via impulsive pinning control

In this paper, the synchronization problem in nonlinearly-coupled multi-weighted complex networks with parameter uncertainties and multiple delays, where both internal time-varying delays and multiple coupling time-varying delays are included, is investigated by adopting a pinning impulsive control scheme, which combines the merits of pinning control and impulsive control. Impulsive pinning control ratio has been applied to select controlled nodes at each impulsive instant. Based on the Lyapunov function method, sufficient conditions for achieving complete synchronization of multi-weighted complex networks have been derived. And numerical simulations are presented to demonstrate the validity and efficacy of our derived theoretical results, which show that under the criteria proposed in this paper, multi-weighted complex networks with parameter uncertainties and multiple delays, could achieve complete synchronization by applying pinning impulsive control. Besides, taking bus lines as the network nodes, a public traffic roads network model with multi-weights is established and analyzed numerically as an application of the proposed multi-weighted complex network model.

Internal feedback in the cortical perception–action loop enables fast and accurate behavior

Animals move smoothly and reliably in unpredictable environments. Models of sensorimotor control, drawing on control theory, have assumed that sensory information from the environment leads to actions, which then act back on the environment, creating a single, unidirectional perception-action loop. However, the sensorimotor loop contains internal delays in sensory and motor pathways, which can lead to unstable control. We show here that these delays can be compensated by internal feedback signals that flow backward, from motor toward sensory areas. This internal feedback is ubiquitous in neural sensorimotor systems, and we show how internal feedback compensates internal delays. This is accomplished by filtering out self-generated and other predictable changes so that unpredicted, actionable information can be rapidly transmitted toward action by the fastest components, effectively compressing the sensory input to more efficiently use feedforward pathways: Tracts of fast, giant neurons necessarily convey less accurate signals than tracts with many smaller neurons, but they are crucial for fast and accurate behavior. We use a mathematically tractable control model to show that internal feedback has an indispensable role in achieving state estimation, localization of function (how different parts of the cortex control different parts of the body), and attention, all of which are crucial for effective sensorimotor control. This control model can explain anatomical, physiological, and behavioral observations, including motor signals in the visual cortex, heterogeneous kinetics of sensory receptors, and the presence of giant cells in the cortex of humans as well as internal feedback patterns and unexplained heterogeneity in neural systems.

New general decay results for a fully dynamic piezoelectric beam system with fractional delays under memory boundary controls

In this paper, we investigate the general stability results of a fully dynamic piezoelectric beam system with internal fractional delays under memory boundary controls. Firstly, by introducing two new equations and using two Volterra's inverse operators to deal with fractional delay terms and boundary memory terms, respectively, a new equivalent system is obtained. Secondly, by combining Faedo–Galerkin approximations with the compactness argument, we prove the local existence and uniqueness of weak solution. Finally, under a broader class of kernel functions, by constructing Lyapunov functionals and new equations and applying some technical lemmas, we establish the optimal and explicit energy decay results for two cases, namely, initial values and without imposing initial values equal to 0, that is, . It is worth pointing out that we focus more on the analysis of , because the stability results of are special cases of . This is the first time to analyze the stability of strong coupling problem by combining internal fractional delay and boundary viscoelastic damping. The obtained general decay results are not necessarily exponential or polynomial, which generalize the relevant results in the existing literature.