Delay Measurements Research Articles

Dynamic analysis of a syphilis epidemic model with time delay and control measures

Dynamic analysis of a syphilis epidemic model with time delay and control measures

Highly accurate absolute optical transfer delay measurement over a long distance assisted by the pulse time signal

In this paper, an absolute optical transfer delay measurement method based on pulse time signal, pseudo-random code phase, and microwave phase is proposed. By employing two-stage integer ambiguity resolution, not only can a measurement range of several hundred kilometers be achieved, but sub-picosecond level measurement accuracy can also be attained. A test system was built in the laboratory and experimentally verified on a fiber optic link. The experimental results verify an accuracy of ±0.1 ps in measuring an ultrahigh-accuracy optical delay line. In addition, long fiber is also tested, which proves that a measurement range of at least 100 km can be achieved. The refresh rate of the measurement results can reach 100 ms each time.

Improving Highway Work Zone Mobility in the Developing World: A Systematic Literature Review of Work Zone Delay Measures and Technological Solutions

Improving Highway Work Zone Mobility in the Developing World: A Systematic Literature Review of Work Zone Delay Measures and Technological Solutions

Distributed driving electric vehicle lateral stability control method considering time delay

This paper introduces a novel control method to address lateral stability challenge in distributed driving electric vehicles. By considering inherent time delay and unknown sensor measurement error generated from design, manufacturing, and external disturbances, the proposed approach achieves better robustness. Firstly, we establish a two-degree-of-freedom (2-DOF) dynamic model for lateral motion of an electric vehicle driven by in-wheel motors (EV-DIM). Based on this model, a control system considering time delay and unknown sensor measurement error is constructed. The control system incorporates a controller based on a dual domination gains observer, and its global asymptotic stability is rigorously proved by the Lyapunov method. Numerical simulations and co-simulations via CarSim and Simulink verify the method’s effectiveness. Compared to the sliding mode control, the proposed method shows better performance which indicates this approach promising for enhancing lateral stability of an electric vehicle.

Measurement of Tunable Optical Delay Using Wavelength Conversion and Fiber Dispersion

In fiber communication system, delay elements are essential for coherent receivers and in the situation of time division multiplexing. Optical communication is transmitted with light. It has a propagation delay. So, in this system, the performance of optical delay element is demonstrated on wavelength conversion, effects of single mode fiber (SMF) dispersion and fiber length. A numerical simulation is used to predict the performance of delay element for different experimental conditions. It has been proven that when the wavelength is changed and its element covers the entire C band. The system is used with the suitable optical pump power and various fiber lengths. It is accomplished with the various parameters by using Opti-system Software. The system operates near 1550 nm and generates delays time approximately 2.65 nanoseconds. In this paper, the performance value is also stated the table which is comparison of theorical result and practical result of delay time.

Coaxial cable delay measurement with different methods: analyzing influential factors and quantifying numerical effects

Abstract Most of the timing scenarios call for the need of precise delay measurement and compensation for coaxial cables. However, experience to date has shown that the cable delay can only be characterized by other physical quantities such as time interval or group delay, etc. In this paper, the principles of three existing commonly used measurement methods were discussed and the various factors that can affect the measurement results were analyzed. Measurement setups and the corresponding uncertainty budgets for the three techniques were then designed and explained. With the aim to quantify numerical effects of the influential factors, specific experiments on a 50 m antenna cable were conducted on time interval measurement to obtain the optimal range of the instrument’s trigger level based on external pulses with different rise time settings, as well as on group delay measurement to determine the influence of different frequency aperture settings. Then, experiments using the relatively proper parameters, which we believe, to the optimal extent, would mitigate the measurement uncertainties were performed. In order to ensure the measurement consistency across the methods, the measurement results were compared and cross-validated to obtain the recommended selections of parameters to align the measurements for coaxial cable delay utilizing the different methods.

Clinical Impact of 3- versus 5-Minute Delay and 30- versus 60-Second Intervals on Unattended Automated Office Blood Pressure Measurements.

Guidelines advise automated office blood pressure (AOBP) with an initial 5-minute delay and multiple measurements at least 60 seconds apart. Recent studies suggest that AOBP may be accurate with shorter delays or intervals, but evidence in clinical settings is limited. Patients referred to one hypertension (HTN) center underwent 24-hour ambulatory blood pressure monitoring (ABPM) and one of four non-randomized, unattended AOBP protocols: a 3- or 5-minute delay with a 30 or 60-second interval, i.e., 3min/30sec/30sec, 3/60/60, 5/30/30 and 5/60/60 protocols. HTN was defined as systolic blood pressure ≥140 or diastolic blood pressure ≥90 mmHg. We compared differences in mean blood pressure and HTN classification between average AOBP and awake-time ABPM by t-tests and Fisher's exact test. Among 212 participants (mean 58.9 years, 61% women, 25% Black), there was substantial overlap in the probability distributions of awake-time ABPM and each of the three AOBP measures. Systolic blood pressure means were similar between the 5/60/60 and 3/30/30 protocols and 5/30/30 and 3/60/60 protocols. The 5/30/30 was associated with a higher proportion of systolic HTN, while the 3/60/60 protocol was associated with a higher proportion of diastolic HTN. There were no significant differences in systolic or diastolic HTN between 5/60/60 and 3/30/30 protocols with respect to awake-time ABPM. In this quality improvement study, the shortest AOBP protocol did not differ significantly from the longest protocol. The time savings of shorter protocols may improve AOBP adoption in clinical practice without meaningfully compromising accuracy.

Improving Non-Line-of-Sight Identification in Cellular Positioning Systems Using a Deep Autoencoding and Generative Adversarial Network Model

Positioning service is a critical technology that bridges the physical world with digital information, significantly enhancing efficiency and convenience in life and work. The evolution of 5G technology has proven that positioning services are integral components of current and future cellular networks. However, positioning accuracy is hindered by non-line-of-sight (NLoS) propagation, which severely affects the measurements of angles and delays. In this study, we introduced a deep autoencoding channel transform-generative adversarial network model that utilizes line-of-sight (LoS) samples as a singular category training set to fully extract the latent features of LoS, ultimately employing a discriminator as an NLoS identifier. We validated the proposed model in 5G indoor and indoor factory (dense clutter, low base station) scenarios by assessing its generalization capability across different scenarios. The results indicate that, compared to the state-of-the-art method, the proposed model markedly diminished the utilization of device resources and achieved a 2.15% higher area under the curve while reducing computing time by 12.6%. This approach holds promise for deployment in future positioning terminals to achieve superior localization precision, catering to commercial and industrial Internet of Things applications.

Towards fault-tolerance of IMA with safe dynamic reconfiguration

Integrated Modular Avionics (IMA) is essential to modern avionics. It increases the possibilities for reuse of software and hardware resources by system integrators, through the use of standardized communication interfaces and operating system services. Meanwhile, the safety requirements of DO-297 dictate that the system architecture must prevent common cause failures and that a single failure cannot disable any critical function. As a result, critical functions have to be allocated redundantly to additional resources at integration-time. In the spirit of IMA, it may be desirable to pool together these resources so that they can be allocated to any critical function at run-time. For this, a way to redefine the communication between individual allocations of functions is necessary. In this paper, we demonstrate and evaluate a prototypical implementation of a message router that allows us to dynamically reconfigure the communication between the allocated functions, using only standardized communication interfaces and operating system services of ARINC 653. We discuss the safety implications of such an approach and how it may be possible to mitigate them, evaluate the feasibility of our approach using a combination of end-to-end delay measurements and on-target tracing, and verify our assumptions about the individual factors contributing to the end-to-end delay using a discrete event simulation. We find that the approach is feasible, but the usefulness for critical functions is limited by the communications overhead from routing the messages, insufficient real-time guarantees of standardized operating system services, and missing global time synchronization.

Stock price delay and the cross-section of expected returns: A story of night and day

We examine how individual stock price reacts to intraday and overnight market information. By examining stock betas, we document a stark gap between day beta and night beta and nontrivial asynchronous beta, which captures the slow diffusion of information. We provide evidence that this information delay can predict future stock returns over a one-month period. Long-short portfolios sorted on the gap between day beta and night beta and asynchronous beta generate raw returns of 0.8% and 0.39% and risk-adjusted alphas of 0.77% and 0.28% per month. These results are robust to alternative asset pricing models and when controlling for firm characteristics, such as size, book-to-market ratios, liquidity, investor recognition and limits-to-arbitrage characteristics. We also explore the heterogeneity of the information delay premium and find that the predictive power of information delay for future return is stronger among small, value firms, less visible firms, illiquid firms and firms with higher limit-to-arbitrage. We also provide evidence that our measure of price delay indeed offers incremental information for cross-section return prediction after we explicitly control for the conventional measure of Hou and Moskowitz (2005)’s price delay.

Robust state estimation for uncertain linear discrete systems with state delay and random measurement losses

Robust state estimation for uncertain linear discrete systems with state delay and random measurement losses

Determination of acoustic properties of paraffin oil mixed with activated coal nanoparticles or SPAN80 using only BAW time delay measurement

An important aspect of controlling the properties of liquids relates to their use in modern engines powered by composite materials. In this context, controlling the properties of industrial fluids containing micro- and nanoscale particles is essential. Understanding the temperature-dependent behavior of fluid density and elasticity is crucial for proper engine operation. Seven physical parameters of pure paraffin oil, paraffin oil with varying concentrations of activated coal nanoparticles or sorbitane monooleate (SPAN 80) were simultaneously determined using only BAW time delay measurement in the single experimental run. This technique relies on propagating LBAW through the test fluid and measuring the time delay and amplitude of these waves at different temperatures. By calculating temperature coefficients for velocity, density, time delay, and expansion using well-established formulas the physical properties of fluids under study were determined. The frequency of the LBAW used in the experiment was 13 MHz. The length of the liquid sample in the propagation direction of LBAW was ∼ 5 mm. The experiments were carried out within a temperature range of −20 °C to +90 °C. The volume of the test sample was around 1 milliliter. The comparison of the physical properties of different suspensions under these conditions allows us to demonstrate the dependence of the measured properties on the type and composition of the medium tested.

SuperSIM: a comprehensive benchmarking framework for neural networks using superconductor Josephson devices

Abstract This paper introduces SuperSIM, a benchmarking framework tailored for neural networks using superconducting Josephson devices, specifically focusing on Adiabatic Quantum Flux Parametron (AQFP) based Processing-in-Memory (PIM) architectures. Our framework offers in-depth architecture-level simulations and performance assessments to enhance AQFP PIM chip development. It supports single and multi-bit PIM designs, various AQFP memory cell types, and diverse clocking methods. Additionally, it integrates circuit-level models for precise energy, delay, and area measurements, ensuring accurate performance evaluation. The framework includes application, device, and architectural layers for versatile configurations and cycle-accurate energy, latency, and area simulations. Experiments validate our framework, with case studies on algorithm and architecture-level features, examining data precision, crossbar size, operating frequency and clocking scheme impacts on computational accuracy, energy use, overall latency and hardware cost.

Price delay and herding: evidence from the cryptocurrency market

PurposeThe purpose of this study is to investigate how the price delay of cryptocurrencies to market news affects the herding behavior of investors, particularly during turbulent events such as the COVID-19 period.Design/methodology/approachThe paper investigates the presence of herding behavior by using Cross-Sectional Absolute Deviation (CSAD) measures. We also investigate the herding activity in the crypto traders’ behavior during up and down-market movements periods and under investor extreme sentiment conditions. The speed of cryptocurrencies’ price response to the information embedded in the market is assessed based on the price delay measure proposed by Hou and Moskowitz (2005).FindingsOur findings suggest that cryptocurrencies characterized by high price delays exhibit more herding among investors, thereby highlighting higher degrees of market inefficiencies. This is also apparent during periods of extreme investor sentiment. We also document an asymmetric herding behavior across cryptocurrencies that present different levels of price speed adjustments to market news during bullish and bearish market conditions. Our results are consistent and robust across different sub-periods, various market return estimations and different price delay frequencies.Practical implicationsThe study provides crucial guidelines for investors’ asset allocation and risk management strategies. This study is also valuable to regulators and policymakers, particularly in light of the increasing importance of financial reforms aimed at mitigating market distortions and enhancing the resilience of the cryptocurrency market. More specifically, regulations that improve the market’s information efficiency should be prioritized to speed up the response time of cryptocurrency prices to market information, which can help reduce the investors' herding behavior.Originality/valueThis paper makes a novel contribution to the academic literature by investigating the unexplored relationship between cryptocurrency price delays and the presence of herding behavior among investors, especially in times of uncertainty such as the COVID-19 pandemic.

Attosecond delays in X-ray molecular ionization.

The photoelectric effect is not truly instantaneous but exhibits attosecond delays that can reveal complex molecular dynamics1-7. Sub-femtosecond-duration light pulses provide the requisite tools to resolve the dynamics of photoionization8-12. Accordingly, the past decade has produced a large volume of work on photoionization delays following single-photon absorption of an extreme ultraviolet photon. However, the measurement of time-resolved core-level photoionization remained out of reach. The required X-ray photon energies needed for core-level photoionization were not available with attosecond tabletop sources. Here we report measurements of the X-ray photoemission delay of core-level electrons, with unexpectedly large delays, ranging up to 700 as in NO near the oxygen K-shell threshold. These measurements exploit attosecond soft X-ray pulses from a free-electron laser to scan across the entire region near the K-shell threshold. Furthermore, we find that the delay spectrum is richly modulated, suggesting several contributions, including transient trapping of the photoelectron owing to shape resonances, collisions with the Auger-Meitner electron that is emitted in the rapid non-radiative relaxation of the molecule and multi-electron scattering effects. The results demonstrate how X-ray attosecond experiments, supported by comprehensive theoretical modelling, can unravel the complex correlated dynamics of core-level photoionization.

HOLISMOKES - XII. Time-delay measurements of strongly lensed Type Ia supernovae using a long short-term memory network

Strongly lensed Type Ia supernovae (LSNe Ia) are a promising probe with which to measure the Hubble constant ($H_0$) directly. To use LSNe Ia for cosmography, a time-delay measurement between multiple images, a lens-mass model, and a mass reconstruction along the line of sight are required. In this work, we present the machine-learning network which is a combination of a long short-term memory network (LSTM) and a fully connected neural network (FCNN). The is designed to measure time delays on a sample of LSNe Ia spanning a broad range of properties, which we expect to find with the upcoming Rubin Observatory Legacy Survey of Space and Time (LSST) and for which follow-up observations are planned. With follow-up observations in the $i$ band (cadence of one to three days with a single-epoch $5 depth of 24.5 mag), we reach a bias-free delay measurement with a precision of around 0.7 days over a large sample of LSNe Ia. The is far more general than previous machine-learning approaches such as the random forest (RF) one, whereby an RF has to be trained for each observational pattern separately, and yet the outperforms the RF by a factor of roughly three. Therefore, the is a very promising approach to achieve robust time delays in LSNe Ia, which is important for a precise and accurate constraint on $H_0$.

Corrective Evaluation of Response Capabilities of Flexible Demand-Side Resources Considering Communication Delay in Smart Grids

With the gradual increase in the proportion of new energy sources in the power grid, there is an urgent need for more flexible resources to participate in short-term regulation. The impact of communication network channel quality will continue to magnify, and factors such as communication latency may directly affect the efficiency and effectiveness of resource regulation. In this context of a large number of flexible demand-side resources accessing the grid, this article proposes a bidirectional channel delay measurement method based on MQTT (Message Queuing Telemetry Transport). It can effectively evaluate the real-time performance of communication links, considering that resources mainly access the grid through the public network. Subsequently, focusing on two typical types of resources on the demand side, namely, split air conditioners and central air conditioners, this article proposes an assessment method for correcting the response capabilities of air conditioning resources considering communication latency. Experimental simulations are conducted, and the results demonstrate that under given communication conditions, this method can more accurately estimate the response capability of air conditioners. This provides a basis for formulating more reasonable scheduling strategies, avoiding excessive or insufficient resource regulation caused by communication issues, and aiding the power grid in achieving precise scheduling.

Zeptosecond‐Scale Single‐Photon Gyroscope

AbstractThis work presents an all‐fiber telecom‐range optical gyroscope employing a spontaneous parametric down conversion crystal to produce ultra‐low intensity thermal light by tracing‐out one of the heralded photons. The prototype exhibits a detection limit on photon delay measurements of 249 zs over a 72 s averaging time and 26 zs in differential delay measurements at s averaging. The detection scheme proves to be the most resource‐efficient possible, saturating of the Cramér–Rao bound. These results are groundbreaking in the context of low‐photon regime quantum metrology, paving the way to novel experimental configurations to bridge quantum optics with special or general relativity.

The Comparison of Dry Hydrostatic Delay Measurement from GPS Ground-Based and Space- Based Receiver

The Comparison of Dry Hydrostatic Delay Measurement from GPS Ground-Based and Space- Based Receiver

Cross-correlation technique for phase error correction in reflection mode terahertz time-domain spectroscopy

Terahertz time-domain spectroscopy in reflection mode geometry provides valuable surface and subsurface information, making it suitable for a layer analysis, coating, and non-destructive testing applications. The exchanging of the sample and reference’s position introduces a phase error when the position or alignment of the sample is not precisely maintained during measurements. This micrometer order of pitch error (Δx) between the reference and the sample could lead to an inherent error in the phase spectrum of the sample. In the present work, a novel approach, to the best of our knowledge, based on the cross-correlation with an envelope technique, has been demonstrated to reduce the uncertainty in the phase and reveal the hidden characteristic features of the given sample in THz TDS spectroscopy. In conjunction with experimental verification, we have employed a finite element analysis in COMSOL Multiphysics to simulate a misplacement error between a lossy dielectric medium (n=1.2 to 3.0 and k=0 to 0.9) and a reference. We have investigated the impact of varying properties of the lossy dielectric medium on delay measurements using a cross-correlation with an envelope analysis. We illustrated and demonstrated the advantage of our approach by measuring the optical properties of Teflon, quartz, and RDX by correcting the misalignment of the 15.75, 17.55, and 20.70 µm ranges, respectively.