Real-time Delay Research Articles

ADHD-related sex differences in fronto-subcortical intrinsic functional connectivity and associations with delay discounting

BackgroundAttention-deficit/hyperactivity disorder (ADHD) is associated with atypical fronto-subcortical neural circuitry and heightened delay discounting, or a stronger preference for smaller, immediate rewards over larger, delayed rewards. Recent evidence of ADHD-related sex differences in brain structure and function suggests anomalies in fronto-subcortical circuitry may differ among girls and boys with ADHD. The current study examined whether the functional connectivity (FC) within fronto-subcortical neural circuitry differs among girls and boys with ADHD compared to same-sex typically developing (TD) controls and relates to delay discounting.MethodsParticipants include 8–12-year-old children with ADHD (n = 72, 20 girls) and TD controls (n = 75, 21 girls). Fronto-subcortical regions of interest were functionally defined by applying independent component analysis to resting-state fMRI data. Intrinsic FC between subcortical components, including the striatum and amygdala, and prefrontal components, including ventromedial prefrontal cortex (vmPFC), anterior cingulate cortex (ACC), and anterior dorsolateral prefrontal cortex (dlPFC), was compared across diagnostic groups overall and within sex. Correlations between intrinsic FC of the six fronto-subcortical pairs and delay discounting were also examined.ResultsBoth girls and boys with ADHD show atypical FC between vmPFC and subcortical regions including the striatum (stronger positive FC in ADHD) and amygdala (weaker negative FC in ADHD), with the greatest diagnostic effects among girls. In addition, girls with ADHD show atypical intrinsic FC between the striatum and dlPFC components, including stronger positive FC with ACC and stronger negative FC with dlPFC. Further, girls but not boys, with ADHD, show heightened real-time delay discounting. Brain–behavior correlations suggest (1) stronger negative FC between the striatal and dlPFC components correlated with greater money delay discounting across all participants and (2) stronger FC between the amygdala with both the dlPFC and ACC components was differentially related to heightened real-time discounting among girls and boys with and without ADHD.ConclusionsOur findings suggest fronto-subcortical functional networks are affected in children with ADHD, particularly girls, and relate to delay discounting. These results also provide preliminary evidence of greater disruptions in fronto-subcortical FC among girls with ADHD that is not due to elevated inattention symptom severity, intellectual reasoning ability, age, or head motion.

Real-time tropospheric delay retrieval with GPS, GLONASS, Galileo and BDS data

The precise point positioning (PPP) is a promising technology for the real-time retrieval of atmospheric parameters with a single receiver in anywhere, all-weather and any time. The real-time atmospheric parameters can be applied to the time-critical meteorology, such as the severe weather nowcasting. The PPP is a satellite-based technology. Multi-constellation integration can enhance satellite geometry and increase measurement redundancy so that the solutions of atmospheric parameters are expected to be improved. Currently, the Global Navigation Satellite System (GNSS) family includes recovered GLONASS and modernized GPS as well as the emerging Galileo and BDS. A week of GNSS observations from 160 stations are processed to retrieve the tropospheric zenith total delay (ZTD) in real time. The four-constellation mixed real-time precise products including satellite orbit and clock corrections are adopted, and their quality is evaluated. The performance of ZTD estimates is assessed in terms of accuracy and convergence time by comparing with final tropospheric ZTD products provided by two analysis centers. The ZTDs retrieved from different constellation combinations (i.e., GPS/GLONASS/Galileo/BDS, GPS/GLONASS, and GPS-only), different processing models for ionospheric delays (i.e., ionospheric-free (IF) combined PPP, and uncombined (UC) PPP), and different modes (i.e., real-time mode, and post-processing mode) are compared.

Signed Real-Time Delay Multiply and Sum Beamforming for Multispectral Photoacoustic Imaging

Reconstruction of photoacoustic (PA) images acquired with clinical ultrasound transducers is usually performed using the Delay and Sum (DAS) beamforming algorithm. Recently, a variant of DAS, referred to as Delay Multiply and Sum (DMAS) beamforming has been shown to provide increased contrast, signal-to-noise ratio (SNR) and resolution in PA imaging. The main reasons for the use of DAS beamforming in photoacoustics are its simple implementation, real-time capability, and the linearity of the beamformed image to the PA signal. This is crucial for the identification of different chromophores in multispectral PA applications. In contrast, current DMAS implementations are not responsive to the full spectrum of sound frequencies from a photoacoustic source and have not been shown to provide a reconstruction linear to the PA signal. Furthermore, due to its increased computational complexity, DMAS has not been shown yet to work in real-time. Here, we present an open-source real-time variant of the DMAS algorithm, signed DMAS (sDMAS), that ensures linearity in the original PA signal response while providing the increased image quality of DMAS. We show the applicability of sDMAS for multispectral PA applications, in vitro and in vivo. The sDMAS and reference DAS algorithms were integrated in the open-source Medical Imaging Interaction Toolkit (MITK) and are available as real-time capable implementations.

Detecting Breaks in Real Time: A Panel Forecasting Approach

We develop a new Bayesian panel regression approach to estimating an unknown number of breaks and forecasting future outcomes in the presence of scarce information from new regimes. Our approach allows the parameters to be heterogeneous across units but assumes that the timing of breaks is common. Exploiting information in the cross-section greatly increases our ability to detect breaks more rapidly in real time compared with univariate time-series approaches applied separately to each cross-sectional unit. Rapid break detection along with shrinkage of the parameter estimates towards a common prior turn out to be key to generating accurate out-of-sample forecasts. In an empirical application to inflation dynamics in 28 EU countries, we find that our heterogeneous panel forecasting method detects breaks with little delay in real time and that this translates into significantly improved out-of-sample forecasts relative to a range of existing methods.

Stochastic prediction of train delays in real-time using Bayesian networks

In this paper we present a stochastic model for predicting the propagation of train delays based on Bayesian networks. This method can efficiently represent and compute the complex stochastic inference between random variables. Moreover, it allows updating the probability distributions and reducing the uncertainty of future train delays in real time under the assumption that more information continuously becomes available from the monitoring system. The dynamics of a train delay over time and space is presented as a stochastic process that describes the evolution of the time-dependent random variable. This approach is further extended by modelling the interdependence between trains that share the same infrastructure or have a scheduled passenger transfer. The model is applied on a set of historical traffic realisation data from the part of a busy corridor in Sweden. We present the results and analyse the accuracy of predictions as well as the evolution of probability distributions of event delays over time. The presented method is important for making better predictions for train traffic, that are not only based on static, offline collected data, but are able to positively include the dynamic characteristics of the continuously changing delays.

FPGA implementation of adaptive time delay estimation for real‐time near‐field electromagnetic ranging

SummaryThe near‐field electromagnetic ranging systems exploit the near‐field phase behavior of low frequency signals for indoor real‐time ranging. Conventionally, phase detector is used to determine the phase of electric and magnetic fields. Subsequently, the phase difference is used to estimate a distance value. In adaptive time delay estimation approach, the time delay between electric and magnetic signals is used instead of phase difference for an estimation. This method does not require a priori knowledge of the transmitting signals and can obtain better performance in low signal‐to‐noise ratio environment. In this paper, we propose a digital near‐field electromagnetic ranging system design and implement it on field‐programmable gate array. This system is composed of time delay estimator, frequency estimator, and received signal strength indicator. A maximum correntropy criterion–based explicit time delay estimation algorithm with a delay in the coefficient update is implemented to estimate the time delay in real time. The fast Fourier transform and received signal strength indicator modules determine the signal frequency and the signal strength received, respectively. Our experimental results indicate that the delayed maximum correntropy criterion–based explicit time delay estimation algorithm has fast convergence rate and good steady‐state performance in an impulsive noise environment.

A Wideband Array Beamforming Method of Conformal Array Based by All-pass Digital Filters

In wideband signal beamforming, the traditional phase-shift method causes pattern pointing deviation and sidelobe widening, so the true time delay should be used to compensate the cannel delay accurately. In this paper, in view of the conformal array wideband beamforming of low computational complexity and high delay precision from a real-time processing, it proposes divide the real-time delay into integer and fractional parts. The low-order FIR filter and the high-order FIR filter are cascaded to used to form the digital beam forming device. The simulation result indicates that, the method proposed in this paper can effectively solve the pattern pointing deviation and sidelobe widening problems.

3:00 PM Abstract No. 141 Interventional radiology patient throughput: application of lean sigma methodology and real-time delay dashboard to improve operations and patient experience

Implementation of large scale EMRs are problematic for optimization of patient experience. A large interventional radiology center performing up to 1000 procedures every month developed a customized, unique, unit-specific patient delay dashboard with real-time feedback to mitigate patient delays. Due to various inefficiencies and limitations, 28% of outpatients are delayed more than 60 minutes past their scheduled procedure start time. The purpose of this project is to achieve a 50% short-term reduction in patient delays greater than 60 minutes and a long-term 50% decrease in delays overall. Additional areas of focus include patient experience e-survey scores, procedure room downtime, reduced PACU capacity, denied insurance days, and financial cost. A multidisciplinary team utilized Lean Sigma methodology for this quality improvement project. A computer application was developed to calculate delays using daily EMR data extracts sent via sftp to our data base. The app supplies a real-time color-coded patient delay dashboard which is prominently displayed on flat screens throughout the department, and alerts staff to individual patient delays in real time with green, yellow, orange, and red lights. A bundled set of interventions targeted preprocedure care coordination and scheduling, outpatient prerounding, reduction of the PT/INR requirement, and the development of an IR bedside service. Patient delays were reduced by 27% in the > 60 minute category (p>0.05) from a baseline 5-month period in January 2016 to a corresponding period in May 2017. Top box scores for timeliness improved 21% on patient e-surveys (n = 802). An anticipated reduction in hospital insurance denied days, due to improved throughput, facilitated funding to open an additional procedure suite and add the bedside services team. Interventions resulted in significant improvement in patient delays, patient experience scores, and denied days. The invention, design, and implementation of a real-time unit-specific dashboard supplied by a data dump from the EMR was invaluable in helping to promote team awareness and transparency regarding delays and throughput.

Evaluating the First-Mover's Advantage in Announcing Real-Time Delay Information

(1) Problem definition: Internet-based technology advancements have enabled service providers to disseminate real-time delay estimates to customers who are strategic and delay-sensitive. In a market with two service providers who compete for market share, we investigate whether one of the service providers (the technology leader L) should make the first move to announce her real-time delay information, when her competitor (the follower F) can opt to respond. (2) Academic/Practical Relevance: From L's viewpoint, it is crucial to evaluate the impact of delay announcements on her market share and whether the technology investment required for such an initiative is justified---an important question that has not been addressed in the delay announcement literature in such a setting. (3) Methodology: We model and analyze the leader-follower setting as a sequential game and employ continuous-time Markov chains to address the queueing aspects of our research questions. (4) Results: We find that L's optimal action depends on the relative service capacities of the service providers: When L has significantly lower service capacity (roughly more than 20% lower), it is optimal for her to initiate delay announcements. On the other hand, when she has significantly higher capacity (roughly more than 20% higher), it is optimal for her not to initiate delay announcements. When service capacities are not significantly different, her optimal action depends on system load. (5) Managerial Implications: Managers of service providers with significantly higher service capacities should expect market share erosion to result from real-time delay broadcast. For a significantly lower-capacity service provider, delay announcements can be considered a strategic remedy for capacity shortage.

Adaptive time-delay estimation based on normalized maximum correntropy criterion for near-field electromagnetic ranging

Indoor location systems can track objects using near-field electromagnetic ranging technology (NFER). However, the ranging error can be large because the phase difference between the electronic and magnetic fields cannot be measured directly. This study proposes a method that adopts an adaptive time-delay estimation algorithm based on a normalized maximum correntropy criterion (NMCC-ATDE) instead of exploiting the phase behavior of the electromagnetic signal for near-field ranging. In the NMCC-ATDE algorithm, the input signal is normalized to mitigate any sudden increase in the input signal. As our simulation results reveal, compared to the algorithms based on maximum correntropy criterion and normalized least mean square, the NMCC-ATDE algorithm can estimate the time delay in real time with a fast convergence rate and small steady-state error.

Modeling and analyzing real-time wireless sensor and actuator networks using actors and model checking

Programmers often use informal worst-case analysis and debugging to ensure that schedulers satisfy real-time requirements. Not only can this process be tedious and error-prone, it is inherently conservative and thus likely to lead to an inefficient use of resources. We propose to use model checking to find a schedule which optimizes the use of resources while satisfying real-time requirements. Specifically, we represent a Wireless sensor and actuator network (WSAN) as a collection of actors whose behaviors are specified using a Java-based actor language extended with operators for real-time scheduling and delay representation. We show how the abstraction mechanism and the compositionality of actors in the actor model may be used to incrementally build a model of a WSAN's behavior from node-level and network models. We demonstrate the approach with a case study of a distributed real-time data acquisition system for high-frequency sensing using Timed Rebeca modeling language and the Afra model checking tool.

Constrained Controller Design for Real-time Delay Recovery in Metro Systems

Constrained Controller Design for Real-time Delay Recovery in Metro Systems

Real-time DSP-based time delay estimation using two sensors

ABSTRACTThere are few available approaches for time delay estimation (TDE) which offer with a potential to be implemented as real-time-embedded systems. Most of these lose accuracy in reverberant and highly noisy environments. In this paper, we initially proposed a 2-dimensional (2D) signal based on the cross-correlation. Then, we proposed two approaches for TDE, based on this 2D signal. There are two main advantages for using the proposed approaches. The first merit is that using a large amount of information about the correlation between the received signals allows a more robust TDE against noise and reverberation, when compared to the other possible techniques. The second one is that the number of samples to calculate the TDE algorithms is decreasing significantly, which is reducing the computational complexity. This paper also proposes a feasible hardware structure to implement the proposed approaches on digital signal processor embedded systems in real time.

Proof of principle of an on-line digitizer with ±18 ppm repeatability and 1.2 μs real-time delay for power converters control loop

The proof of principle of an on-line digitizer designed to be integrated into the digital control loop of a high-voltage modulator for ultra-repeatable power converters is presented. The presented selective analogue zoom allows digitizing with ± 18 ppm repeatability the voltage around the nominal level (10 V± 1 V) and, at the same time, the initial transients with relaxed performance. In addition, in order not to jeopardize the digital control loop stability, the whole digitizing system has to introduce a low real-time delay; this is assessed to be less than 1.2 μs. Initially, the specifications of the real-time control are presented and translated into data acquisition requirements. Then, the main design choices of the digitizer are discussed and Pspice simulation results are reported to validate the concept design. Finally, experimental results of a validation case study developed for the power converter designed at ETH Zurich and University of Laval for the new linear particle accelerator under study at CERN, the Compact LInear Collider CLIC, are reported and compared with the simulation outcomes.

Greater delay discounting among girls, but not boys, with ADHD correlates with cognitive control

ABSTRACTCognitive neuroscience models suggest both reward valuation and cognitive control contribute to reward-based decision-making. The current study examined the relationship between cognitive control and delay discounting (i.e., choosing smaller, immediate over larger, delayed rewards) in a large sample of boys and girls diagnosed with attention-deficit/hyperactivity disorder (ADHD; N = 95) and typically developing control children (TD; N = 59). Specifically, we examined performance on multiple measures of cognitive control (i.e., Go/No-Go task, Stop Signal task, and Spatial Span task) and delay discounting (i.e., Classic Delay Discounting and Real-Time Delay Discounting tasks), as well as the relationship between these measures. Results indicated that sex moderated the effects of group on task performance. Specifically, girls with ADHD, but not boys with the disorder, exhibited atypical delay discounting of real-time rewards. Results from correlational analyses indicated that delay discounting and cognitive control were not significantly correlated in the overall sample. Multiple regression analyses demonstrated that among girls with ADHD poorer spatial working memory and inhibitory control predicted greater real-time discounting. Collectively, findings provide support for distinct patterns of cognitive control and delay discounting among school-aged girls and boys with ADHD. Additionally, findings suggest that among girls with ADHD, those who exhibit relatively poor working memory and inhibitory control might be a particularly vulnerable subgroup with the greatest propensity to exhibit maladaptive decision-making.

Efficient Ignorance: Information Heterogeneity in a Queue

How would the growing prevalence of real-time delay information affect a service system? We consider a single-server queueing system where customers arrive according to a Poisson process and the service time follows an exponential distribution. There are two streams of customers, one informed about real-time delay and the other uninformed. The customers’ uninformed behavior may be due to information ignorance or rational behavior in the presence of an information fee. We characterize the equilibrium behavior of customers with information heterogeneity and investigate how the presence of a larger fraction of informed customers affects the system performance measures, i.e., throughput and social welfare. We show that the effects of growing information prevalence on system performance measures are determined by the equilibrium joining behavior of uninformed customers. Perhaps surprisingly, we find that throughput and social welfare can be unimodal in the fraction of informed customers. In other words, some amount of information heterogeneity in the population can lead to more efficient outcomes, in terms of the system throughput or social welfare, than information homogeneity. For example, under a very mild condition, throughput in a system with an offered load of 1 will always suffer if there are more than 58% of informed customers in the population. Moreover, it is shown that for an overloaded system with offered load sufficiently higher than 1, social welfare always reaches its maximum when some fraction of customers is uninformed of the congestion level in real time. The online appendix is available at https://doi.org/10.1287/mnsc.2017.2747 . This paper was accepted by Gad Allon, operations management.

All-optical tunable delay line based on nonlinearities in a chalcogenide microfiber coil resonator

We propose an all-optical tunable delay line based on nonlinear effects in a two-turn chalcogenide microfiber coil resonator (MCR). Continuous rotation of light due to coupling between the two uniform MCR turns at the resonance induces a time delay. Using numerical simulation, we show the possibility of designing a continuously tunable all-optical and real-time delay line, taking advantage of the high Kerr nonlinear effect in a chalcogenide glass-based MCR. The threshold power for making the Kerr nonlinearity in the chalcogenide sulfide glass (Ge20Ga5Sb10S65, also known as 2S2G) MCR is less than 0.1 W. By selecting an appropriate pump power, one can adjust the time delay in the proposed MCR delay line as desired. Results of numerical simulations show that the time delay in an appropriately designed two-turn MCR can be tuned in the range of 24–147 ps with a bandwidth of ∼4.1 GHz. Pulse broadening and distortion related to group velocity dispersion (GVD) and the self-phase modulation (SPM) effect of the proposed microfiber coil delay line (MCDL) are also studied.

Property Analysis of the Real-Time Uncalibrated Phase Delay Product Generated by Regional Reference Stations and Its Influence on Precise Point Positioning Ambiguity Resolution

The real-time estimation of the wide-lane and narrow-lane Uncalibrated Phase Delay (UPD) of satellites is realized by real-time data received from regional reference station networks; The properties of the real-time UPD product and its influence on real-time precise point positioning ambiguity resolution (RTPPP-AR) are experimentally analyzed according to real-time data obtained from the regional Continuously Operating Reference Stations (CORS) network located in Tianjin, Shanghai, Hong Kong, etc. The results show that the real-time wide-lane and narrow-lane UPD products differ significantly from each other in time-domain characteristics; the wide-lane UPDs have daily stability, with a change rate of less than 0.1 cycle/day, while the narrow-lane UPDs have short-term stability, with significant change in one day. The UPD products generated by different regional networks have obvious spatial characteristics, thus significantly influencing RTPPP-AR: the adoption of real-time UPD products employing the sparse stations in the regional network for estimation is favorable for improving the regional RTPPP-AR up to 99%; the real-time UPD products of different regional networks slightly influence PPP-AR positioning accuracy. After ambiguities are successfully fixed, the real-time dynamic RTPPP-AR positioning accuracy is better than 3 cm in the plane and 8 cm in the upward direction.

Phân tích các kỹ thuật đánh giá chậm trễ tiến độ dự án xây dựng - Ứng dụng thực tế tại dự án Luồng cho tàu biển tải trọng lớn vào sông Hậu

Schedule delays occur frequently in construction projects around the world and Vietnam; it probably leads to damages, impacts on financial matters and even causes myriad disputes in litigation among project parties. Hence, many delay analysis techniques have been proposed and used for analyzing schedule delay problems, namely the real-time delay, concurrent delay, pacing delay, acceleration schedule, float ownership and its consumption, resource allocation and productivity loss. However, no universal technique can solve all complex project situations and is widely accepted by project participants due to the inability of existing approaches to address thoroughly all aforementioned delay issues. This paper examines current delay analysis techniques by applying a real case study to identify which is the most ideal technique to give a reliable and an accurate result that can ensure a greatly acceptable outcome in resolving delay claims. Study results revealed that currently ideal technique is still necessary improved because of its shortcomings. Further researches may also develop an effective approach in full compliance with professional softwares that can solve all identified delay schedule-related problems.

FRAM for the Cherenkov Telescope Array: an update

The Cherenkov Telescope Array (CTA) is a project to build a new generation ground-based gammaray observatory. The FRAM – F(/Ph)otometric Robotic Atmospheric Monitor – is a device, which can provide it with the Vertical Aerosol Optical Depth (VAOD) maps in the field of view of the CTA in almost real time (delay in minutes). The FRAM is a small fast robotic astronomical telescope with a large field of view and a sensitive CCD camera. It uses stellar photometry to measure atmospheric extinction across the field of view and uses it to calculate the VAOD. In this contribution, results of first few months of operations of the prototype and outlook for deployment at the CTA site will be presented.