Time Delay Analysis Research Articles

Relativistic time delay analysis of pulsar signals near ultracompact objects

Relativistic time delay analysis of pulsar signals near ultracompact objects

Prediction method of particle size qualification rate of high-pressure roller mill based on end-edge-cloud synergy

The pass rate of granules is an essential indicator during the high-pressure grinding process, as it accurately reflects the processing quality. Currently, the pass rate of granules is detected primarily based on manual experience judgments or offline inspections. Hence, this article presents a methodology for predicting the pass rate of granularity via an optimized support vector regression approach improved through genetic algorithms. Initially, a time-delay analysis method based on the particle swarm optimization algorithm is applied to mitigate the effects of time delays between the granularity pass rate and other data, thus aligning the dataset on a temporal scale. Subsequently, the feature data were selected using the maximum information coefficient analysis technique, which identified the most significant variables for inclusion in the training and testing sets of the predictive model. Predictions are then made using a support vector machine model that has been enhanced via genetic algorithm optimization. Furthermore, an online prediction model has been established, enabling real-time forecasting of the granularity pass rate and online model updates through root mean square propagation gradient descent optimization algorithm. This method leverages end-edge-cloud collaboration to provide a smart detection mechanism for the throughput rate of particles in high-pressure grinding mills. Experimental results demonstrate that, compared to traditional time-delay analysis, the improved time-delay analysis method proposed in this study is more effective and accurate. Simultaneously, the ɛ-GASVR granularity pass-rate prediction model proposed in this article achieved an R2 of 0.89.

Flow control and imbibition dynamics studies in paper membranes using inert additives

Regulating fluid transport and efficiently controlling imbibition dynamics across the surface of paper assays may increase the detection sensitivity in medical diagnostic applications. The present paper deals with inert additives strategically implemented on various cellulose-based filter-paper membrane surfaces to control the flow dynamics. Studies have been carried out to investigate the effect of additive positioning, additive amount, and the cascading effect of the additive on time delay. Fluid-imbibed images have been processed via mean grayscale intensity variation to understand the saturation extent qualitatively. The tactical application of additives resulted in a flow time increment of up to 121.6 %. A flow time delay analysis was carried out to display the effect of the influencing parameters. Further, imbibition dynamics in the additive-laden paper membrane were captured using a modified Lucas-Washburn model. Finally, the extent of reusability of the paper membranes used was investigated using various drying procedures.

Uncertainty Degradation Model for Initiating Explosive Devices Based on Uncertain Differential Equations

The performance degradation of initiating explosive devices is influenced by various internal and external factors, leading to uncertainties in their reliability and lifetime predictions. This paper proposes an uncertain degradation model based on uncertain differential equations, utilizing the Liu process to characterize the volatility in degradation rates. The ignition delay time is selected as the primary performance parameter, and the uncertain distributions, expected values and confidence intervals are derived for the model. Moment estimation techniques are employed to estimate the unknown parameters within the model. A real data analysis of ignition delay times under accelerated storage conditions demonstrates the practical applicability of the proposed method.

Kinetic insights into ammonia-hydrogen doped ignition and emission assisted by nanosecond pulsed discharge

Non-equilibrium plasma is applied for the first time to ignite the ammonium-hydrogen mixture and reduce the NOx/N2O emission with effect in this work. Gas chromatography (GC) experiments as well as a detailed kinetic model, including neutral molecules, free radicals, charged particles, vibratory excited states, and electron excited states, are integrated to investigate the kinetic process of ammonia-hydrogen doped ignition and NOx/N2O emission facilitated by nanosecond pulsed discharge. The numerical model closely matches the GC-measured values of NH3 consumption, H2 increase, and N2O production. Pathway fluxes of important species and sensitivity analysis of ignition delay time reveal that the addition of non-equilibrium plasma has an obvious promotion effect on ammonia and hydrogen-doped oxidation and ignition. The initial ignition temperature significantly impacts the ignition delay time, with a more pronounced plasma-promotion effect observed at lower temperatures. Conversely, as the hydrogen mixing ratio increases, the ignition delay time decreases, yet the generation of NO and N2O increases. This is attributed to the heightened production of H and NH through elementary reactions such as NH3+HNH2+ H2, H + O2O + OH, and OH + H2H + H2O. Nevertheless, NO and N2O emissions are reduced by 1-2 orders of magnitude with plasma assistance compared to auto-ignition. The reduction in NO emissions can be attributed to increased consumption in the pathway of NO + NH2N2 + H2O and decreased formation in the pathways of HNO + O2HO2 + NO and NH + NON2O + H. Additionally, it was discovered that the electron attachment dissociation reaction e + N2O → O− + N2 predominantly contributes to the reduction of N2O. These research findings significantly contribute to advancing our understanding of the kinetics involved in ammonia-hydrogen doped ignition and emissions, particularly with plasma assistance, for potential engine applications.

A review of research on social studies instruction for students with intellectual disabilities.

The content of social studies encompasses various topics such as culture, citizenship, values, geography, and history. However, social studies has historically been an under-researched academic content area for students with intellectual disabilities. The aim of this study was to identify and summarize empirical research on social studies instruction for students with intellectual disabilities. We searched for articles in two electronic databases from 2000 to 2023. We applied seven inclusion criteria to 1709 articles that emerged in databases. A total of 13 empirical studies met the inclusion criteria. We conducted a narrative review across these 13 studies. Results showed that students with intellectual disabilities improved social studies skills through effective instructional strategies including graphic organizers, technology-based instruction, time delay, and task analysis. Also, social studies instruction for students with intellectual disabilities mostly focused on history and geography. We discussed the findings along with their limitations and provided recommendations for future research.

Externalities from the confinement of a railway: Analysis of the barrier effect

In this paper, we present a mixed qualitative-quantitative approach to analyse the multiple dimensions of the barrier effect caused by the removal of all at-level pedestrian crossings on a railway in a residential area of Santiago, Chile, as part of a new suburban rail service. A set of interviews with a wide range of stakeholders is followed by a quantitative analysis of time delays and extra discomfort for pedestrians, as we measure both the horizontal and vertical detours on walking distance and time, due to having to cross on pedestrian overpasses and underpasses. We find that (i) the new suburban rail service is a source of social inclusion on a metropolitan scale (accessibility gains) and of social exclusion on a more local scale, due to a barrier effect (ii) the confinement of the railway produces strong negative impacts on pedestrians that need to cross the railway, by increasing walking times and by worsening their perception of security and comfort (iii) underpasses and overpasses increase between twofold and fourfold the time needed to cross the railway on average, relative to the case of at-level crossings, (iv) taking into account the increased physical burden and insecurity perceived on overpasses and underpasses, weighted walking times increase up to ten times relative to at-level crossing, and (v) women, elderly people and pedestrians with heavy luggage are more affected by the increased walking time. Traditional methods employed to analyse large-scale transport projects should assess the negative implications of the barrier effect on local communities, as well as the relief measures designed to reduce local segregation, especially in vulnerable communities. The results of this study are useful to quantify the social value of such relief measures, particularly in highly unequal urban settings.

Bias-dependent electron velocity and short-channel effect in scaling sub-100 nm InAlN/GaN HFETs

This work reports on the extraction and simulation of the electron velocity–gate voltages relationship for sub-100 nm InAlN/GaN heterojunction field-effect transistors (HFETs). A peak electron velocity (ve) at an electron density (ns) of 0.41 × 1013 cm−2 was observed at 1.06 × 107 cm/s in an InAlN/GaN HFET with 60 nm gate length (Lg) by delay time analysis. The ve at a high ns of 1.5 × 1013 cm−2 was observed at 0.6 × 107 cm/s. This peak ve behavior is explained by polarization Coulomb field (PCF) scattering and optical phonon scattering based on a Monte Carlo method. As Lg scaled from 350 to 60 nm, the current gain cutoff frequency (fT) and transconductance (gm) were improved. However, the thermal performance was degraded with a bad figure of merit P150 °C. Although a weakening of the control capability of Vgs on ns (Δns/ΔVgs) was observed in the shorter Lg device, which leads to a decrease in device gm, the larger electron velocity by the increased lateral electric field (E) and the larger Δve/ΔVgs by the increased PCF scattering still enhance the peak gm. Results indicate that the enhancement of Δve/ΔVgs is a vital method to strengthen the modulation of the gate on current and to suppress the short channel effect in GaN HFET. Our work supports a deeper understanding and analysis of sub-100 nm InAlN/GaN HFET device performance and physical mechanisms.

A comprehensive study of orbital evolution of LMC X-4: existence of a second derivative of the orbital period

ABSTRACT We report here results from pulse arrival time delay analysis of the eclipsing high-mass X-ray binary (HMXB) pulsar LMC X-4 using observations made with the Rossi X-ray Timing Explorer, XMM–Newton, NuSTAR (Nuclear Spectroscopic Telescope ARray), and AstroSat. Combining the orbital parameters determined from these observations with the historical measurements dating back to 1998, we have extended the Tπ/2 epoch history of LMC X-4 by about 4600 binary orbits spanning about 18 yr. We also report mid-eclipse time measurements (Tecl) using data obtained from wide-field X-ray monitors of MAXI-GSC (Monitor of All-sky X-ray Image – Gas Slit Camera) and Swift-BAT (Burst Alert Telescope). Combining the new Tπ/2 and Tecl estimates with all the previously reported values, we have significantly improved the orbital evolution measurement, which indicates that the orbital period is evolving at a time-scale ($P_{\rm orb}/\dot{P}_{\rm orb}$) of about 0.8 Myr. For the first time in an accreting X-ray pulsar system, we confirm the existence of a second derivative of the orbital period, having an evolution time-scale ($\dot{P}_{\mathrm{ orb}}/\ddot{P}_{\mathrm{ orb}}$) of about 55 yr. Detection of a second derivative of the orbital period in LMC X-4 makes its orbital evolution time-scale more uncertain, which may also be true for other HMXBs. Independent solutions for the orbital evolution measurement using the mid-eclipse data and the pulse timing data are consistent with each other, and help us put an upper limit of 0.009 on the eccentricity of the binary system.

Double Hopf bifurcation analysis of time delay coupled active control system

In this paper, the stability analysis of double Hopf bifurcation is carried out based on the time delay coupled active control system by using the related theory of bifurcation analysis. We got the stability switching region of the system with respect to time delay. The time delay and coupling strength are selected as the bifurcation parameters, then the normal form of the coupled time delay active control system is obtained by using the multi-scale method, and the dynamic behavior near the bifurcation point is obtained. So the parameter region of the stable periodic solution and the stable quasi-periodic solution are obtained. The analytical solution of the system is then solved by using the multi-frequency homotopy analysis method (MFHAM) to verify the existence of the unstable periodic solution. Finally, numerical simulation is executed to verify the theoretical results.

Time-delayed causal network analysis of meteorological variables and air pollutants in Baguio city

Air pollution contributes significantly to climate change and has recently become a significant concern. Previous studies on the interplay between air quality and the environment, such as meteorological variables, have hinted at their relevance in predicting air quality. While air quality prediction has been extensively explored, only a few studies have investigated the causal interactions, and no study has looked into identifying time-delayed causality between individual meteorological factors and air pollutants. In this work, we have deployed sensors in Baguio City, renowned as the “Summer Capital of the Philippines”, and collected data from September 2022 to April 2023. Convergent Cross Mapping (CCM) is then used to infer the time-delayed causation network for PM1, PM2.5, PM10, VOC, and local meteorological variables. Baguio City faces environmental challenges from urbanization and influx of tourists. Here, the top meteorological variables are identified and characterized according to the strength and delay of influences on air pollutants. Wind direction emerges as a leading influencer driving air quality instantly, while pollutants reciprocate with delayed feedback. Temperature holds sway after a day, with pollutants impacting it after eight days on average. Furthermore, links from wind speed to PM concentrations are observed as mediators in causal pathways. Here, the maximum lag delay is only nine days. This work highlights the intricate interdependence of local meteorological factors and air quality, pioneering the identification of time delays that optimize causal influences between these variables. The results of this work offer valuable insights into environmental management and the formulation of mitigation measures.

A time-delayed evolutionary game analysis of new energy vehicles development considering subsidy and carbon tax

With economic and social development, the transport sector is growing rapidly, leading to a surge in energy consumption and environmental degradation. New Energy Vehicles (NEVs) are regarded as an important tool to alleviate energy and environmental issues, but the market share of NEVs in China is low, and how to increase the market share of NEVs is an urgent issue. This study constructs an evolutionary game model between local governments and automakers to explore the evolutionary stable strategy (ESS) of both under different combinations of subsidy and carbon tax, aiming to find rational policies to promote the development of the NEVs. Considering the possible delay effect of the game process, a time-delayed differential equation is established to analyze the effects of random time delay on the stability of the system. Finally, a numerical simulation is carried out to obtain the following conclusions: constant subsidy and carbon tax policy is not conducive to the proliferation of NEVs, variable subsidy and carbon tax policy is effective in the short term, and variable subsidy and constant carbon tax policy is effective in the long term; strengthening the entry of carbon tax can help to develop the NEVs industry; the initial value will affect the evolution of system under constant policy; excessive time delay can cause the system to lose its original stability.

Experimental analysis and numerical simulation of ignition delay time of diesel fuel using a shock tube

The present work consisted in developing a computational routine for prediction and characterization ignition delay time, pressure, temperature generated and energy released in the combustion process in a shock tube. Mathematical modeling considered the high-pressure region of the shock tube known as the conducted section. The Lazarus code compiler was used to generate the unstructured triangular meshes and to implement the computational routines to simulate the propagation of shock waves inside the shock tube. The mathematical modeling used the geometric parameters of the shock tube of the combustion laboratory of the Federal University of Minas Gerais and was based only on the displacement of the shock wave after the diaphragm rupture. The main objective of the work was the development of computational routines to characterize the shock wave parameters of the ignition delay times of conventional diesel to validate the experimental tests carried out in the shock tube conducted by Santana et al. [3] and compare it with the experimental tests and numerical simulations carried out by other authors available in the literature. A linear regression of the experimental tests conducted by Santana et al. [3] with conventional diesel was performed to obtain the Arrhenius equation for numerical simulation of the ignition delay time of diesel under the following conditions: temperatures from 880 to 1300 K, pressures 24 bar and equivalence ratio 1. The results show good prediction between experimental tests and numerical simulations. Were found delay times ranging from 425 to 1890 μs. Considering all temperature range, the difference between the experimental and simulated test was approximately 15%, this difference also can be explained by the measurement in the shock tube, that the ignition delay time was calculated by the time difference between the passage of the shock wave by the pressure sensor and the start of the ignition detected by the luminosity detection sensor. This work is relevant because it was developed computational routine in open software and the results achieved in the simulation were considered satisfactory, since they are in the same order of magnitude as the results found in the experimental tests carried out by Santana et al. [3] and other works.

Adaptive contrastive learning based network latency prediction in 5G URLLC scenarios

With the increasing demand for 5G Ultra-Reliable Low Latency Communication (URLLC), accurate network time delay analysis is crucial. However, current network latency prediction models designed for 5G URLLC scenarios overlook the multiple downstream tasks case, such as network intrusion detection, recognition of network operational states, and decision-making for network resource scheduling.Furthermore, the robustness of the models needs to be enhanced. In this paper, we propose a Contrastive Convolutional Structure for Network Delay (CCSND), an adaptive contrastive learning framework that utilizes a temporal representation extraction module for capturing temporal periodicity and statistical features. To improve robustness and adaptability in time-series representation, CCSND designs strategic data augmentation methods, including temporal segmentation and delay obscuration. Experiment results on several real-world 5G URLLC scenario datasets demonstrate the superior performance of the proposed CCSND. It outperforms the current state-of-the-art Informer model by 38.7% and the traditional LSTM model by 64.5% in terms of mean squared error (MSE). Our code can be accessed at https://github.com/MerelyBreeze/CCSND.

Designing Immersive Tools for Expert and Worker Remote Collaboration

Remote collaboration between on-site workers and remote experts is challenging due to physical limitations and lack of context sharing. Immersive technologies like Augmented Reality (AR) offer innovative interaction methods. However, workers still need wearable or handheld devices, and restricted viewpoints limit remote experts and overall efficiency. This paper aims to design a framework that enables expert presence and improves worker usability, fostering greater collaboration. Our methodology involves using a collaborative robot (cobot) with a camera, projector, smartphone, and a Virtual Reality (VR) interface. The result enables images and 3D captures of the workspace to be shared with the remote expert, who can freely manipulate the cobot to project inspection guidance cues. This autonomy enhances the expert’s involvement and frees the worker to focus on other essential tasks. We detail the proposed architecture design and setup. Finally, we evaluate the system using time delay and latency technical analysis.

Advanced delay-time analysis applied to carbon black powder production

Advanced delay-time analysis applied to carbon black powder production

Influence of fluidelastic vibration frequency on predicting damping controlled instability using a quasi-steady model in a normal triangular tube array

Researchers have applied theoretical and CFD models for years to analyze the fluidelastic instability (FEI) of tube arrays in steam generators and other heat exchangers. The accuracy of each approach has typically been evaluated using the discrepancy between the experimental critical flow velocity and the predicted value. In the best cases, the predicted critical flow velocity was within an order of magnitude comparable to the measured one. This paper revisits the quasi-steady approach for damping controlled FEI in a normal triangular array with a pitch ratio of P/d=1.375. The method addresses the fluidelastic frequency at the stability threshold as an input parameter for the approach. The excellent agreement between the estimated stability thresholds and the equivalent experimental results suggests that the fluidelastic frequency must be included in the quasi-steady analysis, which requires minimal computing time and experimental data. In addition, the model allows a simple time delay analysis regarding flow convective and viscous effects.

Experimental investigation and theoretical analysis of the breakdown time delay and jitter of multi-gap gas switch gaps.

The gas gap of a multi-gap gas switch can be classified as trigger and self-breakdown gaps based on the breakdown condition. A two-gap gas switch consisting of a trigger gap and a self-breakdown gap is developed to independently study the breakdown characteristics of these two types of switch gaps. Trigger experiments for the switch are conducted under various trigger voltage rise rates and different working coefficients. The experimental results indicate that the trigger gap has significantly more jitter than the self-breakdown gap, and the overall performance of the gas switch is determined primarily by the trigger gap. A novel pre-ionization structure with disks is implemented into the two-gap gas switch, considerably decreasing the breakdown delay of the trigger gap and reducing the jitter to a quarter or even less compared to that without pre-ionization. A calculation model of the breakdown time delay for the trigger gap is provided based on the foundational development of the avalanche. The probability distribution of the time required for the initial electron generation is derived in the absence of pre-ionization. The calculated breakdown time delay agrees well with the experimental results in cases with and without pre-ionization under most trigger settings. The method and principle of calculating the breakdown time delay can analyze the collapse of a gas gap with different electrode configurations (quasi-uniform or uniform electrical fields) and various gas media under a nanosecond pulse voltage.

A Robust Control for a Controllable Suspension System with an Input Time Delay

In this study, a state feedback robust control strategy with time delay dependence for the uncertainty, fault, and input time delay of a vehicle’s controllable suspension system is designed. Firstly, based on the working principle of the adjustable damping suspension system, the total damping force of the suspension is divided into “foundation damping force” and “controllable damping force”, taking the adjustable damping interval as the constraint boundary, which varies with the actuating velocity. Furthermore, based on the sensitivity analysis of the input time delay’s relationship with damping force disturbance, it exerts influence on the controllable damping force part. The associated uncertainty and fault are defined through linear fraction transformation and proportional gain, respectively, and the two are decoupled from the control mechanism. Then, based on the Lyapunov stability theory, a robust control law for the time-delay-dependent H∞ state feedback is designed and transformed into a linear matrix inequality convex optimization problem to solve. Finally, the feasibility and effectiveness of the proposed method are verified by designing different combinations of uncertainty and fault tests and by comparing and analyzing these with the time-delay-independent H2/H∞ robust control strategy under random and pulse road excitation.

Closed-form expressions for the pure time delay in terms of the input and output Laguerre spectra

The pure time delay operator is considered in continuous and discrete time under the assumption of the input signal being integrable (summable) with square. Then the input and the output signals are uniquely given by their Laguerre spectra. It is shown that a discrete convolution operator with polynomial Markov parameters constitutes a common description of the delay operator in the continuous and discrete case. Closed-form expressions for the delay value in terms of the output and input Laguerre spectra are derived. The expressions hold for any feasible value of the Laguerre parameter and can be utilized for e.g. building time-delay estimators that allow for non-persistent input. A simulation example is provided to illustrate the principle of Laguerre-domain time-delay modeling and analysis with perfect disturbance rejection.