Maximum Delay Research Articles

Optimal delay in committees

Delay after disagreement in committee decision making may foster information aggregation but is costly ex post. When there is an upper bound on delay that can be credibly imposed, repeated delays can improve the ex ante welfare of committee members. An ex ante optimal dynamic delay mechanism does not impose the maximum credible delay after each disagreement. Instead, it induces in equilibrium start-and-stop cycles where players alternate between making the maximum concession to avoid disagreement and making no concession at all. The start-and-stop feature is robust to modeling delay cost by discounting instead of money-burning, and the optimal mechanism is shown to be “redesign-proof” when there is also an upper bound on the number of rounds of delay that can be credibly imposed.

The impact of the 2009 influenza pandemic on the seasonality of human respiratory syncytial virus: A systematic analysis.

BackgroundSeveral local studies showed that the 2009 influenza pandemic delayed the RSV season. However, no global‐level analyses are available on the possible impact of the 2009 influenza pandemic on the RSV season.ObjectivesWe aim to understand the impact of the 2009 influenza pandemic on the RSV season.MethodsWe compiled data from published literature (through a systematic review), online reports/datasets and previously published data on global RSV seasonality and conducted a global‐level systematic analysis on the impact of the 2009 influenza pandemic on RSV seasonality.ResultsWe included 354 seasons of 45 unique sites, from 26 countries. Globally, the influenza pandemic delayed the onset of the first RSV season by 0.58 months on average (95% CI: 0.42, 0.73; maximum delay: 2.5 months) and the onset of the second RSV season by a lesser extent (0.25 months; 95% CI: 0.12, 0.39; maximum delay: 3.4 months); no delayed onset was observed for the third RSV season. The delayed onset was most pronounced in the northern temperate, followed by the southern temperate, and was least pronounced in the tropics.ConclusionsThe 2009 influenza pandemic delayed the RSV onset on average by 0.58 months and up to 2.5 months. This suggests evidence of viral interference as well as the impact of public health measures and has important implications for preparedness for RSV season during the ongoing COVID‐19 pandemic and future pandemics.

A Low Insertion Loss Variation Trombone True Time Delay in GaAs pHEMT Monolithic Microwave Integrated Circuit

A wideband true time delay is proposed based on 0.25- μm GaAs pHEMT technology. The novel trombone topology is adopted for achieving low variation in insertion loss of different delay states. The fourth-order and second-order inductive all-pass networks (APNs) are operating as delay cells between input and output lines. By selecting different transmission ways, 3 bit with the step of 14 ps and maximum delay range of 98 ps are realized. Measurement results show the insertion loss of 3.8-10.5 dB over the frequency bandwidth of 6-16 GHz. The variation in insertion loss is less than ±1.4 dB. The chip area with pads is 1.955 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and the power consumption is 110 mW.

THE ALLELOPATHICITY OF RED SPRANGLETOP (Leptochloa chinensis L.) AGAINST GERMINATION AND SEEDLING GROWTH OF RICE (Oryza sativa L.)

Red sprangletop (Leptochloa chinensis L.) is a problematic weed of aerobic rice (Oryza sativa L.) that greatly reduces in yield. The laboratory studies were undertaken to confirm allelopathicity of its plant leachates and soil-decomposition plant residues towards emergence and seedling growth of rice. In first experiment, aqueous extracts from various plant parts of red sprangletop (stem, root, leaves, flower and entire plant) at their 5% (w/v) concentration were applied to germinating rice seeds. In second experiment, soil-decomposed red sprangletop plant residues of variable concentrations (2, 4 and 6% w/w) were used as germination media for rice. Among plant parts, red sprangletop leaves showed maximum allelopathic effect by fully inhibiting the germination of rice while its stem could be positioned at second situation as it caused 60, 73, 84.13 and 86 % reductions in germination percentage, germination index, seedling length and seedling dry biomass of rice as compared with control, respectively. This treatment also resulted in maximum delays in mean germination time (up to 4.80 days) and days taken to 50% germination (up to 4.40 days) of rice. The highest concentrated (6%) soil-decomposed plant residue of red sprangletop significantly diminished the germination percentage, germination index, seedling length and seedling vigor index that were 35.13, 23.26 and 41.61% lower than control. It very well may be presumed that liquid concentrates of leave and stem soil-decomposed plant residues of 6% concentration had different kind of allelochemicals that inhibited the germination, seedling growth and development of rice.

Experimental analysis on burning rate and temperature profile produced by pool fire in a curved tunnel as a function of fire location

To analyze the influence of a curved ceiling and fire location on the combustion characteristics in a utility tunnel, the burning rate and temperature profile produced by a pool fire beneath a curved ceiling were investigated experimentally and theoretically. The results showed that oxygen supply and heat feedback from the surrounding form a competitive mechanism, determining the evolution of the burning rate. A qualitative analysis was performed to elucidate this competitive mechanism. With the fire source moving close to the sidewall, the positive influence from the heat feedback is is gradually compensated for by the negative influence from oxygen supply limitation. Moreover, it was inferred that the magnitude of decline of the burning rate near the wall has a positive correlation with heat release rate of the fire source. A characteristic inclined angle was defined to replace the changing angle of the curved ceiling along the ceiling jet path. Based on the definition of the characteristic ‘inclined angle’ concept, the relationship between the temperature profile beneath the curved ceiling centerline, tunnel height and horizontal position from fire source was unified by an empirical model. The maximum temperature delay beneath the curved ceiling centerline produced by the pool fire was analyzed by radial flow and one-dimensional flow. The proposed models for radial flow and one-dimensional flow were validated and could effectively predict the maximum temperature delay, which can be applied in utility tunnel’s fire protection engineering.

Flexible Control of Two-Channel Transmission and Group Delay in an Optomechanical System with Double Quantum Dots Driven by External Field.

With the presence of a driving field applied to double quantum dots and a control field applied on the cavity, the transmission performance and group delay effect of a probe field have been theoretically studied in a hybrid optomechanical system (HOMS). Due to the interaction between the mechanical mode and the double quantum dots system, double optomechanically induced transparency (OMIT) arises in the HOMS. With the assistance of a driving field, the system can be tuned to switch on any one of the two OMIT windows, switch on both of the two OMIT windows or switch off both of the two OMIT windows by dynamically adjusting control of the optical field and the driving field. Furthermore, the transmitted probe fields of the two OMIT windows can be tuned to be absorbed or amplified with proper parameters of the driving field and control field. Moreover, the transmission properties of the two OMIT windows are asymmetrical. One can obtain the maximum group delay time of the probe field by optimizing the amplitude and phase of the driving field. These results provide a new way for constructing optically controlled nanostructured photonic switch and storage devices.

Exact and heuristic approaches to reschedule helicopter flights for personnel transportation in the oil industry

This paper addresses a real-life short-term rescheduling problem of helicopter flights from one onshore airport to several maritime units in the context of the oil industry. This is a complex and challenging problem to solve because of the particular characteristics observed in practice, such as pending flights transferred from previous days with different recovering priorities, changes in flight timetables and helicopter assignments previously planned for the current day, time windows and minimum time intervals between take-offs from the airport and the maritime units, mandatory flight precedence, maximum flight delays, among many others. The problem consists of determining a daily flight reschedule that satisfies operational constraints and recovers all pending flights, while minimizing flight delays and costs related to helicopter usage and reassignments. We propose two mixed integer programming models to formulate the problem with all relevant characteristics, one based on the extension of traditional network flow models and other that relies on a novel event-based representation of the problem. Additionally, we develop an effective heuristic approach based on constructive and improvement heuristics, able to produce high-quality solutions within acceptable computational times. The results of computational experiments with real-life data provided by an oil company highlight the potential of the proposed approaches to support decision making in this context.

Empirical Analysis of Advanced Power Management with Smart Grid Using IoT & Machine Learning

Although with the use of IoT and machine learning in the traditional grid opens new opportunities. There are a few challenges that have constrained their growth. Some of the challenges are discussed here which can open the door for new researches. When we implement IoT, sensors are the basic component which is used to monitor the transmission line, and they depend on battery life so some energy harvesting technique could be implemented. While information is to send to and forth from the smart meter to cloud through a communication network, packet loss and congestion is a challenging issue. Communication protocol should be chosen to minimize the packet loss and delay in a packet. The congestion in a network causes a delay in packets, it degrades the SG performance sometimes exceeds the maximum tolerable delay. So, it is necessary to optimize network design by integrating the minimum number of gateways, and IoT components. To date, there is no unified standard defined for the smart grid, which causes reliability, interoperability, and security issues, So, there is a need for unified standardization. In this paper, we will explore all these challenges in smart grid technology.

Risk of delay evaluation in real-time train scheduling with uncertain dwell times

While trains travel in a railway network, disturbances may arise and corrective decisions to minimize delay propagation may be necessary to solve conflicting track requests. This problem is known in the literature as the real-time Railway Traffic Management Problem (rtRTMP) and its solutions represent plans of operations that minimize delay propagation due to unexpected disturbances. However, uncertainty may still affect such plans and their expected quality in terms of level of service or risk containment. This article proposes a new approach for the assessment of the risk of onset or worsening of delays associated to an rtRTMP solution when dwell times are uncertain and only an interval representation of them is known to the scheduler. To this aim, the Conditional-Value-at-Risk of the maximum train delay is adopted as risk index. In this study we address both modeling and computational issues, developing and testing a graph-based model to use with an innovative numerical method to obtain a real-time risk evaluation for rtRTMP solutions. The proposed approach is applied on a real case study analyzing the effects of uncertainties of different severity. Promising computational results enable to use the methodology to deal with the rtRTMP taking into account the uncertainty on the involved activities and the risk attitude of the decision-makers at the operational level.

Topological approach to studying mechanochemical effects in the processes of corrosion of metals under stress

It is hereby suggested to use a topological approach based on the principles of synergetics and the theory of catastrophes to describe some aspects of the mechanochemical effect of the sign of deformation in stress corrosion phenomena. It was found that a steel plate being located in an aggressive environment and subjected to additional force impact may be informatively considered as a synergistic system. It has been established that the concept of sensitivity to imperfection can be applied to the interpretation of the deformation sign effect. It has been demonstrated that the violation of the symmetry of the sides of a bent plate is made provision for by the structure of standard models - catastrophes of the «ruffle» type. Possible scenarios for the development of mechanochemical effects are considered, taking into account Maxwell’s principles and maximum delay principles. Topological models which describe both the above-mentioned mechanochemical effect of the deformation sign at small times (within 50 s) and its reversal with time are constructed and analyzed. Further possible directions of investigation of mechanochemical effects in the processes of corrosion of metals under stress are formulated.

Consensus of Multi-Agent Systems with Unbounded Time-Varying Delays

In multi-agent systems with increasing communication distances, the communication delay is time-varying and unbounded. In this paper, we describe the multi-agent system with increasing communication distances as the discrete-time system with non-distributed unbounded time-varying delays and study the consensus problem of the system via the distributed control. This paper uses a time-delay system to model the discrete-time system, and the maximum delay in the time-delay system tends to infinity as time goes on. Furthermore, caused by this property, most of convergence analysis methods for bounded time-delay systems are ineffective. Hence, for any finite integer k&gt;0, the finite-dimensional augmented model of the time-delay system is built in the interval [0,k] to study the system state. Under the weaker topological assumption that the topology containing a spanning tree, the system is proved to achieve a consensus if the growth rate of the maximum delay satisfies some mild constraints, which also are constraints on the growth rate of the maximum communication distance between agents. Furthermore, we characterize that the rate of the system achieving a consensus and the growth rate of the maximum delay are negatively correlated. In other words, the rate of the system achieving a consensus and the growth rate of the maximum communication distance between agents are negatively correlated.

Investigation on Speckle-Free Imaging at the Output of a Multimode Fiber under Various Mode Excitation Conditions

Speckle-free imaging using a multimode fiber has been widely used for imaging systems. Generally, previous work has assumed that all the propagating modes of the fiber are uniformly excited, but the modal power distribution is actually affected by excitation conditions. Here, we propose the utilization of a modal analysis method to study the dependence of the speckle contrast on the modal power distribution by changing the tilt angle of the Gaussian beam and on the group delay time difference caused by different fiber lengths. The results of numerical simulations and experiments show that, with an increase in the tilt angle of the Gaussian beam, the modal power is transferred to higher-order modes and the maximum delay difference between excitation modes becomes larger. Therefore, the inter-mode interference effect is effectively weakened, and the speckle contrast is significantly reduced. The increase in fiber length will also make the delay difference between excitation modes larger and thus the speckle contrast is decreased. For the larger tilt angle of the Gaussian beam, only a shorter optical fiber is required to reduce the speckle contrast significantly. Our work further promotes the use of a multimode fiber to produce speckle-free patterns in laser imaging systems.

Delay dependent criteria for the consensus of second‐order multi‐agent systems subject to communication delay

In this paper, a distributed controller is designed for the consensus of multi-agent systems in which each agent has a general second-order linear dynamic and the information is exchanged over a data-delaying communication network. Using the sensitivity of system poles to the parameters of the control protocol, graphical delay-dependent synthesis conditions are derived to tune the controller gains. A systematic procedure is developed to attain maximum tolerable transmission delay in the system. Moreover, simpler condition is provided for the special case where the second-order model is reduced to a double integrator. Simulation results are presented to illustrate the merits of the proposed scheme compared to some recent rival ones in the literature.

An Advanced Angular Velocity Error Prediction Horizon Self-Tuning Nonlinear Model Predictive Speed Control Strategy for PMSM System

In nonlinear model predictive control (NMPC), higher accuracy can be obtained with a shorter prediction horizon in steady-state, better dynamics can be obtained with a longer prediction horizon in a transient state, and calculation burden is proportional to the prediction horizon which is usually pre-selected as a constant according to dynamics of the system with NMPC. The minimum calculation and prediction accuracy are hard to ensure for all operating states. This can be improved by an online changing prediction horizon. A nonlinear model predictive speed control (NMPSC) with advanced angular velocity error (AAVE) prediction horizon self-tuning method has been proposed in which the prediction horizon is improved as a discrete-time integer variable and can be adjusted during each sampling period. A permanent magnet synchronous motor (PMSM) rotor position control system with the proposed strategy is accomplished. Tracking performances including rotor position Integral of Time-weighted Absolute value of the Error (ITAE), the maximal delay time, and static error are improved about 15.033%, 23.077%, and 10.294% respectively comparing with the conventional NMPSC strategy with a certain prediction horizon. Better disturbance resisting performance, lower weighting factor sensitivities, and higher servo stiffness are achieved. Simulation and experimental results are given to demonstrate the effectiveness and correctness.

Controlling sudden transition between classical and quantum decoherence via squeezing phase of the baths

Correlations in the open quantum systems exhibit a rich phenomenology in various decoherent environments. We theoretically study the dynamics of quantum and classical correlations in a two-qubit system, where each qubit is locally subjected to the relevant squeezed vacuum bath through the non-demolition interaction. Specifically, we unveil the effects of the squeezing phase of the bath and squeezing strength on the intriguing phenomena of freezing discord and sudden transition between classical and quantum decoherence. Remarkably, we show that by proper tuning the squeezing phase one can significantly delay the sudden transition time . Interestingly, we found that the maximum delay in may obtain when the phase difference between the squeezing phase and the phase of the coupling strength is π/2. Consequently, an increase in the leads to the enhancement of time-interval during which quantum discord does not affect by environmental noise. On the other hand, we show that squeezing strength plays a negative role in enhancing sudden transition time and preserving quantum discord. Furthermore, we also show that squeezed bath allows the existence of the time-invariant discord for a broader range of Ohmicity parameter s and initial condition ε. Strikingly our study renders new insights to control and sustain quantum correlations against the detrimental effects of decoherence beyond the conventional protocols.

Arbuscular Mycorrhizal Fungi Inoculation Reduced the Growth of Pre-Rooted Olive Cuttings in a Greenhouse

The effect of commercial mycorrhizal fungi on pre-rooted olive cuttings was assessed. The study consisted of two experiments, the first arranged as a factorial design with three cultivars (Cobrançosa, Madural, and Verdeal Transmontana) and three soil treatments (commercial mycorrhizal fungi, zeolites, and control) and the second as a completely randomized design with three treatments (commercial mycorrhizal fungi, sterilized soil, and control). Cobrançosa grew better than the other cultivars, showing good rooting and initial growth features. Mycorrhizal plants showed reduced growth in comparison to those of the untreated control. This result was explained by competition for photosynthates between plant growth and the expansion of fungi hyphae. Cuttings of reduced leaf area and a twin-wall polycarbonate cover of the greenhouse, somewhat opaque to photosynthetic active radiation, may also have contributed to limit the maximum photosynthetic rate and delay the growth of the inoculated plants. Accordingly, in the mycorrhizal pots, the soil organic carbon (C) increased, probably due to the presence of fungi hyphae in soil samples. Zeolites reduced plant dry matter (DM) yield and tissue phosphorus (P) concentration compared to the control, while increasing the availability in the soil of the cations present in their initial composition. Soil sterilization seems to have reduced soil P bioavailability by inactivating soil enzymes. This study showed that the inoculation with mycorrhizal fungi of pre-rooted cuttings can delay their initial growth. Although these plants may be better prepared to grow in the field, in the short term, their lower development can be a problem for the nurseryman.

97 What Are the Main Delays to Surgery After A Patient Presents with An Acute Type A Aortic Dissection?

Abstract Introduction Acute-aortic-dissection (AAD) represents a serious cardiovascular emergency, with an associated mortality of 1-2% per hour after symptom onset. It is known that the relative infrequency of AAD and plausible differentials can negatively impact on a timely diagnosis. Female sex, absence of typical features and high-risk examination findings (hypotension/pulse deficits) shown to delay diagnosis. In UK, services for AAD are centralised, working on established volume/outcome relationships. However, this has the potential to introduce delays in rapidly diagnosing patients without on-site specialist support and in the logistics of transferring patients across large distances. This study aims to report on time taken for patients to receive surgery after first presentation at local hospital and identify points that contribute to maximal delay. Method Retrospective analysis of all operated type-A-aortic-dissections at our hospital in 2019. Hospital database used to identify patients, and local/referring hospital documentation reviewed to establish times. Results Mean time from A&amp;E presentation to surgery is 8-hours-and-30 minutes (4:16–13:43). Largest contributor to delay is time from A&amp;E admission to CT scan. Conclusions Our findings suggest greatest impact on improving times from presentation to surgery is to increase awareness of AAD in regional, non-specialist hospitals and to encourage rapid imaging.

Supervisory Control of Networked Discrete Event Systems With Timing Structure

In this article, we study the supervisory control problem of networked discrete event systems with timing structure assuming bounded communication delays and intermittent loss of observations. The communication between the plant and the supervisor is through a network that can have several channels, and so communication delays may change the order of event observations by the supervisor. We assume a priori knowledge of the minimal activation time of the plant transitions and the maximum communication delays, and propose an equivalent untimed model that takes into account all possible observation delays and also loss of observations. Based on this model, we formulate a networked supervisory control problem and show that it can be converted into an equivalent range control problem. We also address implementation, and, to this end, we present a representation for networked supervisors that is able to deal with possible loss of synchronization between event occurrence and its observation.

Computation offloading optimization for UAV-assisted mobile edge computing: a deep deterministic policy gradient approach

Unmanned Aerial Vehicle (UAV) can play an important role in wireless systems as it can be deployed flexibly to help improve coverage and quality of communication. In this paper, we consider a UAV-assisted Mobile Edge Computing (MEC) system, in which a UAV equipped with computing resources can provide offloading services to nearby user equipments (UEs). The UE offloads a portion of the computing tasks to the UAV, while the remaining tasks are locally executed at this UE. Subject to constraints on discrete variables and energy consumption, we aim to minimize the maximum processing delay by jointly optimizing user scheduling, task offloading ratio, UAV flight angle and flight speed. Considering the non-convexity of this problem, the high-dimensional state space and the continuous action space, we propose a computation offloading algorithm based on Deep Deterministic Policy Gradient (DDPG) in Reinforcement Learning (RL). With this algorithm, we can obtain the optimal computation offloading policy in an uncontrollable dynamic environment. Extensive experiments have been conducted, and the results show that the proposed DDPG-based algorithm can quickly converge to the optimum. Meanwhile, our algorithm can achieve a significant improvement in processing delay as compared with baseline algorithms, e.g., Deep Q Network (DQN).

A novel design of fast and compact all-optical full-adder using nonlinear resonant cavities

In this paper, we report a new design of an all-optical full-adder using two nonlinear resonators. The PhC-based full-adder consists of three input ports (A, B, and C for input bits), two nonlinear resonant cavities, several waveguides, and two output ports (for the SUM and CARRY). Eight silicon rods and a nonlinear rod composed of doped glass form each resonant cavity. The well-known plane wave expansion technique is used to calculate the photonic band structure. It shows a wide photonic bandgap in the wavelength range of 1365–2074 nm covering the C and L optical transmission bands. The finite-difference time-domain method is applied to study the light propagation inside the full-adder. Our numerical results demonstrate when the incoming light intensity increases, the nonlinear optical Kerr effect appears and controls the direction of light emitted inside the structure as desired. The maximum time delay and footprint of the proposed full-adder are about 3 ps and 758.5 μm2, respectively. Therefore, due to the low time delay and small footprint, the presented design can be used as a basic mathematical operator in the all-optical arithmetic logic unit.