Journal articles: 'Delay optimization'

1

Tennakoon, Hiran, and Carl Sechen. "Nonconvex Gate Delay Modeling and Delay Optimization." IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 27, no. 9 (September 2008): 1583–94. http://dx.doi.org/10.1109/tcad.2008.927758.

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Ren, Zhaolin, Zhengyuan Zhou, Linhai Qiu, Ajay Deshpande, and Jayant Kalagnanam. "Delay-Adaptive Distributed Stochastic Optimization." Proceedings of the AAAI Conference on Artificial Intelligence 34, no. 04 (April 3, 2020): 5503–10. http://dx.doi.org/10.1609/aaai.v34i04.6001.

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In large-scale optimization problems, distributed asynchronous stochastic gradient descent (DASGD) is a commonly used algorithm. In most applications, there are often a large number of computing nodes asynchronously computing gradient information. As such, the gradient information received at a given iteration is often stale. In the presence of such delays, which can be unbounded, the convergence of DASGD is uncertain. The contribution of this paper is twofold. First, we propose a delay-adaptive variant of DASGD where we adjust each iteration's step-size based on the size of the delay, and prove asymptotic convergence of the algorithm on variationally coherent stochastic problems, a class of functions which properly includes convex, quasi-convex and star-convex functions. Second, we extend the convergence results of standard DASGD, used usually for problems with bounded domains, to problems with unbounded domains. In this way, we extend the frontier of theoretical guarantees for distributed asynchronous optimization, and provide new insights for practitioners working on large-scale optimization problems.

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Bhattacharya, Prabhati, and Mark R. Virkler. "Optimization for Pedestrian and Vehicular Delay in a Signal Network." Transportation Research Record: Journal of the Transportation Research Board 1939, no. 1 (January 2005): 115–22. http://dx.doi.org/10.1177/0361198105193900114.

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The efficiency of an arterial network can be enhanced by optimizing the user costs incurred because of delays and other socioeconomic factors. Until recently, research mostly focused on minimizing vehicular delay to optimize user costs. Currently, no signal coordination tool exists to balance delays to both vehicles and pedestrians. A methodology that uses known techniques and available tools to identify an optimal signal coordination plan is developed. Pedestrian delay patterns are obtained from previous research. Delay data for vehicles are based on the modeling of peak-hour traffic conditions in urbanized areas of a hypothetical city. The signal optimization software Synchro (Version 3.2) was used to investigate the variations in vehicle delay with different signal coordination plans and offsets. The results reveal that the best offsets for vehicles and pedestrians are not necessarily the same. Consequently, a signal coordination plan that would benefit both should consider the total user costs of the system. The results show that the highest total pedestrian delay can spike up the user costs more than the highest total vehicular delay. The offset that generates the optimal user cost can be different from the best offset for vehicles or pedestrians. Thus, a balance between pedestrian delay and vehicular delay can be achieved to arrive at an optimal signal coordination plan.

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Wang, Xiao-Dong, and Tom Chen. "Performance and Area Optimization of VLSI Systems Using Genetic Algorithms." VLSI Design 3, no. 1 (January 1, 1995): 43–51. http://dx.doi.org/10.1155/1995/26912.

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A new performance and area optimization algorithm for complex VLSI systems is presented. It is widely believed within the VLSI CAD community that the relationship between delay and silicon area of a VLSI chip is convex. This conclusion is based on a simplified linear RC model to predict gate delays. In the proposed optimization algorithm, a nonlinear, non-RC based transistor delay model was used which resulted in a non-convex relationship between the delay and the silicon area of a VLSI chip. Genetic algorithms are better suited for discrete, non-convex, non-linear optimization problems than traditional calculus-based algorithms. By using the genetic algorithms in the performance and area optimization, we are able to find the optimal values for both delay and silicon area for the ISCAS benchmark circuits.

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Lin, Xuemin. "Delay Optimization in Quorum Consensus." Algorithmica 38, no. 2 (October 10, 2003): 397–413. http://dx.doi.org/10.1007/s00453-003-1066-x.

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Yu, Zhengyao, Vikash V. Gayah, and Eleni Christofa. "Person-Based Optimization of Signal Timing." Transportation Research Record: Journal of the Transportation Research Board 2620, no. 1 (January 2017): 31–42. http://dx.doi.org/10.3141/2620-04.

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Recent studies have proposed the use of person-based frameworks for the optimization of traffic signal timing to minimize the total passenger delay experienced by passenger cars and buses at signalized intersections. The efficiency and applicability of existing efforts, however, have been limited by an assumption of fixed cycle lengths and deterministic bus arrival times. An existing algorithm for person-based optimization of signal timing for isolated intersections was extended to accommodate flexible cycle lengths and uncertain bus arrival times. To accommodate flexible cycle lengths, the mathematical program was redefined to minimize total passenger delay within a fixed planning horizon that allowed cycle lengths to vary within a feasible range. Two strategies were proposed to accommodate uncertain bus arrival times: ( a) a robust optimization approach that conservatively minimized delays experienced in a worst-case scenario and ( b) a blended strategy that combined deterministic optimization and rule-based green extensions. The proposed strategies were tested with numerical simulations of an intersection in State College, Pennsylvania. Results revealed that the flexible cycle length algorithm could significantly reduce bus passenger delay and total passenger delay, with negligible increases in car passenger delay. These results were robust to changes in both bus and car flows. For bus arrival times, the robust optimization strategy seemed to be more effective at low levels of uncertainty and the blended strategy at higher levels of uncertainty. The anticipated benefits decreased with increases in the intersection flow ratio because of the lower flexibility of signal timing at the intersection.

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Kuźmiński, Łukasz, Piotr Maśloch, Marek Bazan, Tomasz Janiczek, Krzysztof Halawa, Henryk Wojtaszek, Ireneusz Miciuła, et al. "Management of Delay Optimization at Intersections." Energies 13, no. 12 (June 15, 2020): 3087. http://dx.doi.org/10.3390/en13123087.

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Congestion extends the time of the journey for both people and goods. Therefore, transport solutions should be optimized. Management scientists and technical scientists worked together in order to develop a proprietary solution to increase efficiency in terms of productivity improvements for intelligent transport systems. The most fundamental functions of management have been paired with a detailed analysis of city traffic. The authors developed a method for determining the order of vehicles at traffic lights and connected it with vehicle-to-vehicle communication and GPS signals. As a result, a novel method to increase the throughput of intersections is presented. This solution generates a sound signal in order to inform the driver that the preceding car has started moving forward. The proposed solution leads to the shortening of the reaction time of the drivers waiting in a queue. This situation is most common at red lights. Consequently, the traffic simulation shows that the discharge of queues at traffic lights may be quicker by up to 13.5%. Notably, that proposed solution does not require any modification of the infrastructure as well as any additional devices for vehicle-to-infrastructure communication at the road intersections. To conclude, proper implementation of the proposed solution will certainly contribute to efficiency improvements within intelligent transport systems, with the potential to reduce traffic jams.

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YE, Ping, Yi-Zhong LI, and Qin XIA. "Delay Optimization Based Overlay Routing Strategy." Chinese Journal of Computers 33, no. 1 (April 22, 2010): 36–44. http://dx.doi.org/10.3724/sp.j.1016.2010.00036.

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Intiso, S., I. Kataeva, E. Tolkacheva, H. Engseth, K. Platov, and A. Kidiyarova-Shevchenko. "Time-Delay Optimization of RSFQ Cells." IEEE Transactions on Appiled Superconductivity 15, no. 2 (June 2005): 328–31. http://dx.doi.org/10.1109/tasc.2005.849823.

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Alpert, C. J., A. Devgan, and C. V. Kashyap. "RC delay metrics for performance optimization." IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 20, no. 5 (May 2001): 571–82. http://dx.doi.org/10.1109/43.920682.

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11

Nayak, Anshuman, Malay Haldar, Prith Banerjee, Chunhong Chen, and Majid Sarrafzadeh. "Power Optimization of Delay Constrained Circuits." VLSI Design 12, no. 2 (January 1, 2001): 125–38. http://dx.doi.org/10.1155/2001/65638.

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We present a framework for combining Voltage Scaling (VS) and Gate Sizing (GS) techniques for power optimizations. We introduce a fast heuristic for choosing gates for sizing and voltage scaling such that the total power is minimized under delay constraints. We also use a more accurate estimate for determining the power dissipation of the circuit by taking into account the short circuit power along with the dynamic power. A better model of the short circuit power is used which takes into account the load capacitance of the gates. Our results show that the combination of VS and GS perform better than the techniques applied in isolation. An average power reduction of 73% is obtained when decisions are taken assuming dynamic power only. In contrast, average power reduction is 77% when decisons include the short circuit power dissipation.

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12

Liang, Xiao (Joyce), S. Ilgin Guler, and Vikash V. Gayah. "Traffic Signal Control Optimization in a Connected Vehicle Environment Considering Pedestrians." Transportation Research Record: Journal of the Transportation Research Board 2674, no. 10 (July 22, 2020): 499–511. http://dx.doi.org/10.1177/0361198120936268.

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This paper proposes a connected vehicle-based traffic signal control scheme that seeks to improve both vehicle and pedestrian operations. Real-time information on vehicle speeds and locations is combined with knowledge of pedestrian arrivals to optimize signal timings that minimize a weighted average of vehicle and pedestrian delays. Such real-time pedestrian information might be available using existing sensors—such as pedestrian push buttons or infrared detectors—as well as in a connected environment. The algorithm implements a rolling-horizon optimization framework that optimizes signal phase sequences over some period but only implements the first phase in the optimized sequence. The results reveal that considering pedestrians in the optimization can improve delays to both pedestrians and vehicles compared with ignoring pedestrians. Within the proposed framework, average vehicle delay increases and average pedestrian delay decreases as more weight is assigned to pedestrian delay in the optimization. In general, the average person delay can be minimized when the relative weight between vehicle and pedestrian delay is consistent with the average occupancy rate of cars. However, a different weight may be chosen to prioritize pedestrian movement, if desired. These results are robust under varying demand levels and demand patterns. The effectiveness of the algorithm decreases as the information level of pedestrian arrivals decreases, and the algorithm becomes ineffective when information from fewer than 60% pedestrians is available. However, the detection of more than 60% of pedestrians can likely be achieved using existing technologies and thus would likely be available in a connected environment.

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13

Duda, Jozef. "Lyapunov Matrices Approach to the Parametric Optimization of a System with Two Delays." Archives of Control Sciences 26, no. 3 (September 1, 2016): 367–81. http://dx.doi.org/10.1515/acsc-2016-0020.

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AbstractIn the paper a Lyapunov matrices approach to the parametric optimization problem of time-delay systems with two commensurate delays and a P-controller is presented. The value of integral quadratic performance index of quality is equal to the value of the Lyapunov functional for the initial function of time-delay system. The Lyapunov functional is determined by means of the Lyapunov matrix.

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14

Liu, Wei Qun, and Xiang Kui Chen. "A Delay-Constrained Multicast Routing Balanced-Optimization Algorithm of Link-Sharing." Applied Mechanics and Materials 152-154 (January 2012): 1834–39. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.1834.

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In multimedia network, Quality of service (QoS) provisioning generally assumes more than one QoS measure which implies that QoS routing can be categorized as an instance of routing subject to multiple constraints: delay, cost, bandwidth, etc. We study the problem of constructing multicast trees to meet the QoS requirements of real-time applications where it is necessary to provide bounded delays among the source and all destinations while keeping overall cost of the multicast tree low. So the cost and computational complexity are analyzed as constructing delay-constrained multicast tree. So as to optimize shortest paths, a new algorithm of ORLSB(optimal routing algorithm for link-sharing balance) is proposed.The link selection function of the algorithm not only considers the priority of the destination nodes, but also takes into account the priority of the low delay path based on local information. Because the multicast tree has fewer possible path, the algorithm reduces the probability of creating multicast tree through the minimum delay path and improves the sharing paths. Simulation results show that this algorithm has balanced cost, delay and computational complexity, and has better overall performance.

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15

Balasubramaniam, Pagavathigounder, Shanmugam Lakshmanan, and Rajan Rakkiyappan. "LMI optimization problem of delay-dependent robust stability criteria for stochastic systems with polytopic and linear fractional uncertainties." International Journal of Applied Mathematics and Computer Science 22, no. 2 (June 1, 2012): 339–51. http://dx.doi.org/10.2478/v10006-012-0025-6.

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LMI optimization problem of delay-dependent robust stability criteria for stochastic systems with polytopic and linear fractional uncertaintiesThis paper studies an LMI optimization problem of delay-dependent robust stability criteria for stochastic systems with polytopic and linear fractional uncertainties. The delay is assumed to be time-varying and belong to a given interval, which means that lower and upper bounds of this interval time-varying delay are available. The uncertainty under consideration includes polytopic-type uncertainty and linear fractional norm-bounded uncertainty. Based on the new Lyapunov-Krasovskii functional, some inequality techniques and stochastic stability theory, delay-dependent stability criteria are obtained in terms of Linear Matrix Inequalities (LMIs). Moreover, the derivative of time delays is allowed to take any value. Finally, four numerical examples are given to illustrate the effectiveness of the proposed method and to show an improvement over some results found in the literature.

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Zhou, Wen, Yun Bai, Jiajie Li, Yuhe Zhou, and Tang Li. "Integrated Optimization of Tram Schedule and Signal Priority at Intersections to Minimize Person Delay." Journal of Advanced Transportation 2019 (July 18, 2019): 1–18. http://dx.doi.org/10.1155/2019/4802967.

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Modern trams, as a rapidly developed high-volume transport model, have strict requirements on schedule, because the delay will reduce the attractiveness of public transportation to passengers. To improve punctuality and reliability, Transit Signal Priority (TSP) has been employed at intersections, which can extend or insert green phase to trams. However, extending or inserting the green phase for every tram might lead to heavy delays to crossing vehicles. To address this problem, this study developed an integrated optimization model on tram schedule and signal priority which can balance the delay between trams and other vehicles to minimize person delay. Three conditional strategies named early green, green extension, and phase insertion are proposed for the signal priority. Simultaneously, arrival time, departure time of trams at stations, and stop line are optimized as well. The proposed model is tested with a numerical case and a real-world case at Ningbo tramline in China. The results indicate that the integrated optimization can reduce the average delay of all passengers on trams and other vehicles, compared to timetable optimization only and TSP only. It is also found that the proposed model is able to adapt to the fluctuation in the ratio of tram passenger to auto vehicle user, compared with only minimizing tram passenger delay or auto vehicle user delay.

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17

Du, Gaoming, Chao Tian, Zhenmin Li, Duoli Zhang, Chuan Zhang, Xiaolei Wang, and Yongsheng Yin. "Delay Bound Optimization in NoC Using a Discrete Firefly Algorithm." Electronics 8, no. 12 (December 9, 2019): 1507. http://dx.doi.org/10.3390/electronics8121507.

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The delay bound in system on chips (SoC) represents the worst-case traverse time of on-chip communication. In network on chip (NoC)-based SoC, optimizing the delay bound is challenging due to two aspects: (1) the delay bound is hard to obtain by traditional methods such as simulation; (2) the delay bound changes with the different application mappings. In this paper, we propose a delay bound optimization method using discrete firefly optimization algorithms (DBFA). First, we present a formal analytical delay bound model based on network calculus for both unipath and multipath routing in NoCs. We then set every flow in the application as the target flow and calculate the delay bound using the proposed model. Finally, we adopt firefly algorithm (FA) as the optimization method for minimizing the delay bound. We used industry patterns (video object plane decoder (VOPD), multiwindow display (MWD), etc.) to verify the effectiveness of delay bound optimization method. Experiments show that the proposed method is both effective and reliable, with a maximum optimization of 42.86%.

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Chen, Qiuxia, Ying Liu, and Haoqi Zhu. "Robust Output Feedback Model Predictive Control for a Class of Networked Control Systems with Nonlinear Perturbation." Mathematical Problems in Engineering 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/154158.

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This paper is concerned with the design problem of robust dynamic output feedback model predictive controllers for a class of discrete-time systems with time-varying network-induced delays and nonlinear perturbation. The designed controllers achieve on-line suboptimal receding horizon guaranteed cost such that the system can be stabilized for all admissible uncertainties. A novel delay compensation strategy is proposed to eliminate the effects of the time-varying network-induced delays. By using multistep prediction and the receding optimization, the delay-dependent sufficient condition is derived for the existence of delay compensation controllers. By employing the cone complementarity linearization (CCL) idea, a nonlinear minimization problem with linear matrix inequality (LMI) constraints is formulated to design the desired output feedback controllers, and an iterative algorithm involving convex optimization is presented to solve the nonlinear minimization problem. Finally, an example is given to illustrate the feasibility and effectiveness of the proposed results.

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Lu, Jianchao, and Baris Taskin. "Post-CTS Delay Insertion." VLSI Design 2010 (February 22, 2010): 1–9. http://dx.doi.org/10.1155/2010/451809.

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A post-clock-tree-synthesis (post-CTS) optimization method is proposed that suggests delay insertion at the leaves of the clock tree in order to implement a limited version of clock skew scheduling. Delay insertion is limited on each clock tree branch simultaneous with a global monitoring of the total amount of delay insertion. The delay insertion for nonzero clock skew operation is performed only at the clock sinks in order to preserve the structure and the optimizations implemented in the clock tree synthesis stage. The methodology is implemented as a linear programming model amenable to two design objectives: fixing timing violations or optimizing the clock period. Experimental results show that the clock networks of the largest ISCAS'89 circuits can be corrected post-CTS to resolve the timing conflicts in approximately 90% of the circuits with minimal delay insertion (0.159 clock period per clock path on average). It is also shown that the majority of the clock period improvement achievable through unrestricted clock skew scheduling are obtained through very limited insertion (43% average improvement through 10% of max insertion).

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Michiels, Wim, and Silviu‐Iulian Niculescu. "Characterization of Delay‐Independent Stability and Delay Interference Phenomena." SIAM Journal on Control and Optimization 45, no. 6 (January 2007): 2138–55. http://dx.doi.org/10.1137/050641223.

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Lin, Zhang, Di Chen Liu, Wu Jun, Qing Fen Liao, Yun Lei, and Fei Fei Dong. "Gobal Optimization Based Power System Stablization with WAMS Time Delay Study." Advanced Materials Research 433-440 (January 2012): 7362–67. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.7362.

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It is very important to take into consideration time delay in wide area power system stability; the design of PSS (Power System Stabilizer) should consider global optimization with WAMS (Wide Area Measurement System) time delay. Newly designed PSS should be insensitive to time delay and suppress internal low frequency oscillations. It is used as feedback signal and is real-time synchronous that WAMS signal shows. Power system is modeled with the consideration of time delay. LMI (Linear Matrix Inequalities) is used to solve the stability condition of time delay system. Based on the time-delay effect of the wide-area measurement signals, this paper redesigned the PSS with global optimization of power system. The attached two-area-four-machine system simulation illustrates that wide-area PSS designed by global optimization with the consideration of time-delay can limit internal low frequency oscillation with time-delay insensitivity, and improve the stability of power system. It implements global optimization of PSS with WAMS time delay stability.

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Regitha, M. R., Dr Paul Varghese, Shailesh Sivan, and Antony Nijo. "Handoff Delay Optimization Using Hybrid Prediction Model." International Journal of Networked and Distributed Computing 6, no. 2 (2018): 99. http://dx.doi.org/10.2991/ijndc.2018.6.2.5.

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Montlaur, A., and L. Delgado. "Flight and passenger delay assignment optimization strategies." Transportation Research Part C: Emerging Technologies 81 (August 2017): 99–117. http://dx.doi.org/10.1016/j.trc.2017.05.011.

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Alpert, C. J., A. Devgan, and S. T. Quay. "Buffer insertion for noise and delay optimization." IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 18, no. 11 (1999): 1633–45. http://dx.doi.org/10.1109/43.806808.

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Xiao, Surong, Chubo Liu, Kenli Li, and Keqin Li. "System delay optimization for Mobile Edge Computing." Future Generation Computer Systems 109 (August 2020): 17–28. http://dx.doi.org/10.1016/j.future.2020.03.028.

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Li, Yitong, Wen Zhan, and Lin Dai. "Rate-Constrained Delay Optimization for Slotted Aloha." IEEE Transactions on Communications 69, no. 8 (August 2021): 5283–98. http://dx.doi.org/10.1109/tcomm.2021.3079513.

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Deng, Jian Qiu, and Cui Hao. "Research on State Feedback Controller of the Networked Control System with Long Delay." Applied Mechanics and Materials 536-537 (April 2014): 1183–86. http://dx.doi.org/10.4028/www.scientific.net/amm.536-537.1183.

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This paper addresses the stabilization and optimization problem of networked control systems (NCSs) with long time delays. According to the actual network conditions, the network time delay is divided into the fixed time delay and the random time delay. Then, the stabilization controller is constructed, where the stabilizing control parameters are obtained with cone complementary linearization (CCL) approach and the optimizing control parameters are solved with estimation of distribution algorithm (EDA) algorithm. Simulation results demonstrate the effectiveness of the proposed methods.

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Sehgal, Jaya, and Poonam Arora. "Delay Optimization in VANET Using Ant Colony Optimization and WI-MAX." International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering 03, no. 08 (August 20, 2014): 11405–12. http://dx.doi.org/10.15662/ijareeie.2014.0308067.

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Wu, Yao, Jian Lu, Hong Chen, and Haifei Yang. "Development of an Optimization Traffic Signal Cycle Length Model for Signalized Intersections in China." Mathematical Problems in Engineering 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/954295.

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The primary objective of this study is to develop an optimization traffic signal cycle length model for signalized intersections. Traffic data were collected from 50 signalized intersections in Xi’an city. Using comprehensive delay data, the optimization cycle length model is re-recalibrated to the Chinese traffic conditions based on the Webster delay model. The result showed that the optimization cycle length model takes vehicle delay time, pedestrian crossing time, and drivers’ anxiety into consideration. To evaluate the effects of the optimization cycle length model, three intersections were selected for a simulation. The delay time and queue length based on the optimization cycle length model and the TRRL model were compared. It was found that the delay times and queue lengths with the optimization cycle length model were significantly smaller than those with the TRRL model. The results suggested that the optimization traffic signal cycle length model was more optimal than the TRRL model.

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Glockner, Gregory D. "Effects of Air Traffic Congestion Delays under Several Flow-Management Policies." Transportation Research Record: Journal of the Transportation Research Board 1517, no. 1 (January 1996): 29–36. http://dx.doi.org/10.1177/0361198196151700104.

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Air traffic delays occur when demand for airports or airspace exceeds available capacity. Consequently, these delay effects can be lessened by increasing capacity or by modifying the air traffic demand. Increasing capacity is an important solution, but it is a long-range option involving major changes such as facility construction, fundamental procedural changes, and improvements in navigational equipment. For short-term decision making a tactical-optimization model can suggest alternative flight plans to reduce delays. However, a tactical-optimization model is extremely complex because of the uncertainty in airport-capacity forecasts, which primarily depend on weather. A practical implementation of a tactical-optimization model must therefore make approximations so that a solution may be computed quickly and be of good quality. A practical model framework for the congestion-delay problem is given; this model framework is a generalization of several other flow-management models. Congested situations are simulated, to compare the practical performance of this model to other air traffic management tactics.

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Trifunovic, Danijela, Milan Petrovic, Goran Milasinovic, Bosiljka Vujisic-Tesic, Marija Boricic, Ivana Nedeljkovic, Vera Jelic, et al. "Pacemaker optimization guided by echocardiography in cardiac resynchronization therapy." Srpski arhiv za celokupno lekarstvo 137, no. 7-8 (2009): 416–22. http://dx.doi.org/10.2298/sarh0908416t.

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Introduction. Cardiac resynchronization therapy (CRT) or biventricular pacing is a contemporary treatment in the management of advanced heart failure. Echocardiography plays an evolving and important role in patient selection for CRT, follow-up of acute and chronic CRT effects and optimization of device settings after biventricular pacemaker implantation. In this paper we illustrate usefulness of echocardiography for successful AV and VV timing optimization in patients with CRT. A review of up-to-date literature concerning rationale for AV and VV delay optimization, echocardiographic protocols and current recommendations for AV and VV optimization after CRT are also presented. Outline of Cases. The first case is of successful AV delay optimization guided by echocardiography in a patient with dilated cardiomyopathy treated with CRT is presented. Pulsed blood flow Doppler was used to detect mitral inflow while programming different duration of AV delay. The AV delay with optimal transmittal flow was established. The optimal mitral flow was the one with clearly defined E and A waves and maximal velocity time integral (VTI) of the mitral flow. Improvement in clinical status and reverse left ventricle remodelling with improvement of ejection fraction was registered in our patient after a month. The second case presents a patient with heart failure caused by dilated cardiomyopathy; six months after CRT implantation the patient was still NYHA class III and with a significantly depressed left ventricular ejection fraction. Optimization of VV interval guided by echocardiography was undertaken measuring VTI of the left ventricular outflow tract (LVOT) during programming of different VV intervals. The optimal VV interval was determined using a maximal LVOT VTI. A month after VV optimization our patient showed improvement in LV ejection fraction. Conclusion. Optimal management of patients treated with CRT integrate both clinical and echocardiographic follow-up with, if needed, echocardiographically guided optimization of AV and VV delays, which offers the possibility of additional clinical improvement in such patients.

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Wei, Qiang, Cheng-jun Xie, Xu-ri Kou, and Wei Shen. "Delay Partial Synchronization of Mutual Delay Coupled Boolean Networks." Measurement and Control 53, no. 5-6 (April 15, 2020): 870–75. http://dx.doi.org/10.1177/0020294019882967.

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This paper studies the delay partial synchronization for mutual delay-coupled Boolean networks. First, the mutual delay-coupled Boolean network model is presented. Second, some necessary and sufficient conditions are derived to ensure the delay partial synchronization of the mutual delay-coupled Boolean networks. The upper bound of synchronization time is obtained. Finally, an example is provided to illustrate the efficiency of the theoretical analysis.

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Li, Guangshun, Jiping Wang, Junhua Wu, and Jianrong Song. "Data Processing Delay Optimization in Mobile Edge Computing." Wireless Communications and Mobile Computing 2018 (2018): 1–9. http://dx.doi.org/10.1155/2018/6897523.

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With the development of Internet of Things (IoT), the number of mobile terminal devices is increasing rapidly. Because of high transmission delay and limited bandwidth, in this paper, we propose a novel three-layer network architecture model which combines cloud computing and edge computing (abbreviated as CENAM). In edge computing layer, we propose a computational scheme of mutual cooperation between the edge devices and use the Kruskal algorithm to compute the minimum spanning tree of weighted undirected graph consisting of edge nodes, so as to reduce the communication delay between them. Then we divide and assign the tasks based on the constrained optimization problem and solve the computation delay of edge nodes by using the Lagrange multiplier method. In cloud computing layer, we focus on the balanced transmission method to solve the data transmission delay from edge devices to cloud servers and obtain an optimal allocation matrix, which reduces the data communication delay. Finally, according to the characteristics of cloud servers, we solve the computation delay of cloud computing layer. Simulation shows that the CENAM has better performance in data processing delay than traditional cloud computing.

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Zhou, Xin, Hexin Zhang, Xiaoxiang Hu, Junjun Hui, and Tianmei Li. "Improved Results on Robust Stability for Systems with Interval Time-Varying Delays and Nonlinear Perturbations." Mathematical Problems in Engineering 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/898260.

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This paper investigated delay-dependent robust stability criteria for systems with interval time-varying delays and nonlinear perturbations. A delay-partitioning approach is used in this paper, the delay-interval is partitioned into multiple equidistant subintervals, a new Lyapunov-Krasovskii (L-K) functional contains some triple-integral terms, and augment terms are introduced on these intervals. Then, by using integral inequalities method together with free-weighting matrix approach, a new less conservative delay-dependent stability criterion is formulated in terms of linear matrix inequalities (LMIs), which can be easily solved by optimization algorithms. Numerical examples are given to show the effectiveness and the benefits of the proposed method.

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Bao, Xu, Yanqiu Li, Jianmin Li, Rui Shi, and Xin Ding. "Prediction of Train Arrival Delay Using Hybrid ELM-PSO Approach." Journal of Advanced Transportation 2021 (June 14, 2021): 1–15. http://dx.doi.org/10.1155/2021/7763126.

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In this study, a hybrid method combining extreme learning machine (ELM) and particle swarm optimization (PSO) is proposed to forecast train arrival delays that can be used for later delay management and timetable optimization. First, nine characteristics (e.g., buffer time, the train number, and station code) associated with train arrival delays are chosen and analyzed using extra trees classifier. Next, an ELM with one hidden layer is developed to predict train arrival delays by considering these characteristics mentioned before as input features. Furthermore, the PSO algorithm is chosen to optimize the hyperparameter of the ELM compared to Bayesian optimization and genetic algorithm solving the arduousness problem of manual regulating. Finally, a case is studied to confirm the advantage of the proposed model. Contrasted to four baseline models (k-nearest neighbor, categorical boosting, Lasso, and gradient boosting decision tree) across different metrics, the proposed model is demonstrated to be proficient and achieve the highest prediction accuracy. In addition, through a detailed analysis of the prediction error, it is found that our model possesses good robustness and correctness.

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Li, Xu-Guang, Silviu-Iulian Niculescu, and Arben Çela. "An iterative frequency-sweeping approach for stability analysis of linear systems with multiple delays." IMA Journal of Mathematical Control and Information 36, no. 2 (November 22, 2017): 379–98. http://dx.doi.org/10.1093/imamci/dnx050.

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AbstractIn this article, we study the stability of linear systems with multiple (incommensurate) delays, by extending a recently proposed frequency-sweeping approach. First, we consider the case where only one delay parameter is free while the others are fixed. The complete stability w.r.t. the free delay parameter can be systematically investigated by proving an appropriate invariance property. Next, we propose an iterative frequency-sweeping approach to study the stability under any given multiple delays. Moreover, we may effectively analyse the asymptotic behaviour of the critical imaginary roots (if any) w.r.t. each delay parameter, which provides a possibility for stabilizing the system through adjusting the delay parameters. The approach is simple (graphical test) and can be applied systematically to the stability analysis of linear systems including multiple delays. A deeper discussion on its implementation is also proposed. Finally, various numerical examples complete the presentation.

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Liang, Y. C., R. Zhang, and J. M. Cioffi. "Transmit Optimization for MIMO-OFDM With Delay-Constrained and No-Delay-Constrained Traffic." IEEE Transactions on Signal Processing 54, no. 8 (August 2006): 3190–99. http://dx.doi.org/10.1109/tsp.2006.874769.

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Lien, Chang-Hua, and Ker-Wei Yu. "LMI OPTIMIZATION APPROACH FOR DELAY-DEPENDENT H∞ CONTROL OF TIME-VARYING DELAY SYSTEMS." Asian Journal of Control 8, no. 2 (October 22, 2008): 190–96. http://dx.doi.org/10.1111/j.1934-6093.2006.tb00269.x.

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Li, Rui, Changjiang Zheng, and Wenquan Li. "Optimization Model of Transit Signal Priority Control for Intersection and Downstream Bus Stop." Mathematical Problems in Engineering 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/9487190.

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Transit signal priority has a positive effect on improving traffic condition and level of transit service in the urban area. In this paper, a passenger-based transit signal priority (TSP) optimization model is formulated to optimize intersection signal phasing based on minimizing accessibility-based passenger delay at the intersection and increased waiting-delay at the downstream bus stop simultaneously. Genetic Algorithm is utilized to calculate passenger-based optimization model that is calibrated by evening rush hour actual traffic data (17:30–18:30, October 13th–October 15th, 2015) along Shuiximen Boulevard in Nanjing, China. The performance of the proposed optimization model in decreasing delay and improving system reliability is simulated and evaluated by VISSIM-based simulation platform, and the results illustrate that the proposed optimization model presents promising outcomes in decreasing accessibility-based passenger delay at intersection (average reduction of 12%) and passenger waiting-delay at downstream bus service stop (average reduction of 18%) compared with traditional vehicle-based TSP optimization method in rush hour.

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Dou, Chun-xia, Zhi-sheng Duan, Xing-bei Jia, Xiao-gang Li, Jin-zhao Yang, Ting Gui, and Ye-fei Bi. "Delay-Dependent Robust Stabilization for Nonlinear Large Systems via Decentralized Fuzzy Control." Mathematical Problems in Engineering 2011 (2011): 1–20. http://dx.doi.org/10.1155/2011/605794.

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A delay-dependent robust fuzzy control approach is developed for a class of nonlinear uncertain interconnected time delay large systems in this paper. First, an equivalent T–S fuzzy model is extended in order to accurately represent nonlinear dynamics of the large system. Then, a decentralized state feedback robust controller is proposed to guarantee system stabilization with a prescribedH∞disturbance attenuation level. Furthermore, taking into account the time delays in large system, based on a less conservative delay-dependent Lyapunov function approach combining with linear matrix inequalities (LMI) technique, some sufficient conditions for the existence ofH∞robust controller are presented in terms of LMI dependent on the upper bound of time delays. The upper bound of time-delay and minimizedH∞performance index can be obtained by using convex optimization such that the system can be stabilized and for all time delays whose sizes are not larger than the bound. Finally, the effectiveness of the proposed controller is demonstrated through simulation example.

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Kumar Sharma, Devendra, Brajesh Kumar Kaushik, and R. K. Sharma. "Impact of driver size and interwire parasitics on crosstalk noise and delay." Journal of Engineering, Design and Technology 12, no. 4 (September 30, 2014): 475–90. http://dx.doi.org/10.1108/jedt-08-2012-0036.

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Purpose – The purpose of this research paper is to analyze the combined effects of driver size and coupling parasitics on crosstalk noise and delay for static and dynamically switching victim line. Furthermore, this paper shows the effect of inductance on delay and qualitatively optimizes its value to obtain minimum delay. Design/methodology/approach – The interwire parasitics are the primary sources of crosstalk or coupled noise that may lead to critical delays/logic malfunctions. This paper is based on simulating a pair of distributed resistance inductance capacitance (RLC) interconnects coupled capacitively and inductively for measurements of crosstalk noise/delay. The combined effects of driver sizing and interwire parasitics on peak overshoot noise/delay are observed through simulation program with integrated circuit emphasis (SPICE) simulations for different switching patterns. Furthermore, the analysis of inductive effect on propagation delay as a function of coupling capacitance is carried out and the optimization of delay is worked out qualitatively. The simulations are carried out at 0.13 μm, 1.5 V technology node. Findings – This paper observes the contradictory effects of coupling parasitics on wire propagation delay; however, the effect on peak noise is of a different kind. Further, this paper shows that the driver size exhibits opposite kind of behavior on propagation delay than peak over shoot noise. It is observed that the delay is affected in presence of inductance; thus, the optimization of delay is carried out. Originality/value – The effects of driver sizing and interwire parasitics are analyzed through simulations. The optimum value of coupling capacitance for delay is found qualitatively. These findings are important for designing very large scale integration (VLSI) interconnects.

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Grzyb, Sławomir, and Przemysław Orłowski. "Multi-Objective Control Optimization for Congestion Avoidance in Computer Networks." Modelling, Measurement and Control A 93, no. 1-4 (December 31, 2020): 39–44. http://dx.doi.org/10.18280/mmc_a.931-406.

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Effective congestion control is an issue strongly impacting basic features demanded from modern network environment as reliability, high and stable throughput, and low delays. These characteristics define the quality of communication channels. Optimizing network nodes configuration for only one of mentioned features, can exacerbate other parameters. This paper focuses on avoiding and alleviating network congestions using multi-objective optimization for gain setting of used controllers. Unlike in other presented approaches, in this case the non-stationary, discrete, dynamical model is discussed. The significant advantage of this approach is in the better reflection of the real environment conditions, where the transmission delay is floating. As the further development of the control strategy, the controller with the memory of previous steps have been deployed. Such control strategy mitigates the unfavorable impact of extended delays. Both proposed control strategies tune the presented model of communication channel to alleviate the results of sudden, unexpected network state changes. It is obtained by maximization of available bandwidth usage combined with minimization of buffer utilization. This supports avoiding undesirable congestion effects like packet dropping, retransmissions, high delay, and low network throughput.

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Wang, Mingming, Li Wang, Xinyue Xu, Yong Qin, and Lingqiao Qin. "Genetic Algorithm-Based Particle Swarm Optimization Approach to Reschedule High-Speed Railway Timetables: A Case Study in China." Journal of Advanced Transportation 2019 (March 20, 2019): 1–12. http://dx.doi.org/10.1155/2019/6090742.

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In this study, a mixed integer programming model is proposed to address timetable rescheduling problem under primary delays. The model considers timetable rescheduling strategies such as retiming, reordering, and adjusting stop pattern. A genetic algorithm-based particle swarm optimization algorithm is developed where position vector and genetic evolution operators are reconstructed based on departure and arrival time of each train at stations. Finally, a numerical experiment of Beijing-Shanghai high-speed railway corridor is implemented to test the proposed model and algorithm. The results show that the objective value of proposed method is decreased by 15.6%, 48.8%, and 25.7% compared with the first-come-first-service strategy, the first-schedule-first-service strategy, and the particle swarm optimization, respectively. The gap between the best solution obtained by the proposed method and the optimum solution computed by CPLEX solver is around 19.6%. All delay cases are addressed within acceptable time (within 1.5 min). Moreover, the case study gives insight into the correlation between delay propagation and headway. The primary delays occur in high-density period (scheduled headway closes to the minimum headway), which results in a great delay propagation.

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Liu, Xu, Zhenhao Li, Peng Xu, and Jialing Li. "Joint Optimization for Bandwidth Utilization and Delay Based on Particle Swarm Optimization." IEEE Access 9 (2021): 92125–33. http://dx.doi.org/10.1109/access.2021.3091693.

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Jiang, Yu, Zhaolong Xu, Xinxing Xu, Zhihua Liao, and Yuxiao Luo. "A Schedule Optimization Model on Multirunway Based on Ant Colony Algorithm." Mathematical Problems in Engineering 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/368208.

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In order to make full use of the slot of runway, reduce flight delay, and ensure fairness among airlines, a schedule optimization model for arrival-departure flights is established in the paper. The total delay cost and fairness among airlines are two objective functions. The ant colony algorithm is adopted to solve this problem and the result is more efficient and reasonable when compared with FCFS (first come first served) strategy. Optimization results show that the flight delay and fair deviation are decreased by 42.22% and 38.64%, respectively. Therefore, the optimization model makes great significance in reducing flight delay and improving the fairness among all airlines.

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Zoutendijk, Micha, and Mihaela Mitici. "Probabilistic Flight Delay Predictions Using Machine Learning and Applications to the Flight-to-Gate Assignment Problem." Aerospace 8, no. 6 (May 28, 2021): 152. http://dx.doi.org/10.3390/aerospace8060152.

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The problem of flight delay prediction is approached most often by predicting a delay class or value. However, the aviation industry can benefit greatly from probabilistic delay predictions on an individual flight basis, as these give insight into the uncertainty of the delay predictions. Therefore, in this study, two probabilistic forecasting algorithms, Mixture Density Networks and Random Forest regression, are applied to predict flight delays at a European airport. The algorithms estimate well the distribution of arrival and departure flight delays with a Mean Absolute Error of less than 15 min. To illustrate the utility of the estimated delay distributions, we integrate these probabilistic predictions into a probabilistic flight-to-gate assignment problem. The objective of this problem is to increase the robustness of flight-to-gate assignments. Considering probabilistic delay predictions, our proposed flight-to-gate assignment model reduces the number of conflicted aircraft by up to 74% when compared to a deterministic flight-to-gate assignment model. In general, the results illustrate the utility of considering probabilistic forecasting for robust airport operations’ optimization.

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Jamal, Arshad, Muhammad Tauhidur Rahman, Hassan M. Al-Ahmadi, Irfan Ullah, and Muhammad Zahid. "Intelligent Intersection Control for Delay Optimization: Using Meta-Heuristic Search Algorithms." Sustainability 12, no. 5 (March 2, 2020): 1896. http://dx.doi.org/10.3390/su12051896.

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Traffic signal control is an integral component of an intelligent transportation system (ITS) that play a vital role in alleviating traffic congestion. Poor traffic management and inefficient operations at signalized intersections cause numerous problems as excessive vehicle delays, increased fuel consumption, and vehicular emissions. Operational performance at signalized intersections could be significantly enhanced by optimizing phasing and signal timing plans using intelligent traffic control methods. Previous studies in this regard have mostly focused on lane-based homogenous traffic conditions. However, traffic patterns are usually non-linear and highly stochastic, particularly during rush hours, which limits the adoption of such methods. Hence, this study aims to develop metaheuristic-based methods for intelligent traffic control at isolated signalized intersections, in the city of Dhahran, Saudi Arabia. Genetic algorithm (GA) and differential evolution (DE) were employed to enhance the intersection’s level of service (LOS) by optimizing the signal timings plan. Average vehicle delay through the intersection was selected as the primary performance index and algorithms objective function. The study results indicated that both GA and DE produced a systematic signal timings plan and significantly reduced travel time delay ranging from 15 to 35% compared to existing conditions. Although DE converged much faster to the objective function, GA outperforms DE in terms of solution quality i.e., minimum vehicle delay. To validate the performance of proposed methods, cycle length-delay curves from GA and DE were compared with optimization outputs from TRANSYT 7F, a state-of-the-art traffic signal simulation, and optimization tool. Validation results demonstrated the adequacy and robustness of proposed methods.

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Zhou, Xi Yi, Ge Zhang, and Li Qiang Liu. "Hierarchical Mobile IPv6 Based Handoff Optimization Scheme." Advanced Materials Research 798-799 (September 2013): 460–63. http://dx.doi.org/10.4028/www.scientific.net/amr.798-799.460.

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Hierarchical mobile IPv6 fastens the binding update process of micro mobile handoff and reduces handoff delay. A large number of binding updates and registrations increase signaling load and lengthen handoff delay. For this reason, it is proposed to apply tunneling mechanism to hierarchical mobile IPv6 optimization scheme (T-HMIPv6) to obtain care-of address in advance based on handoff information, conduct duplicate address detection, and complete local binding update while building a tunnel. Simulation experiments show that compared with hierarchical mobile IPv6, this scheme can greatly reduce handoff delay and packet loss rate and effectively improve mobile node's macro handoff performance.

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Cao, Yang, and Jian Wang. "An Optimization Method of Passenger Assignment for Customized Bus." Mathematical Problems in Engineering 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/7914753.

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This study proposes an optimization method of passenger assignment on customized buses (CB). Our proposed method guarantees benefits to passengers by balancing the elements of travel time, waiting time, delay, and economic cost. The optimization problem was solved using a Branch and Bound (B&B) algorithm based on the shortest path for the selected stations. A simulation-based evaluation of the proposed optimization method was conducted. We find that a CB service can save 38.33% in average travel time, 38.33% in average waiting time, and 27.78% in delay penalties, all at an acceptable ticket price. The variations are caused by different degrees of busload. A detailed investigation revealed that a CB can significantly reduce travel time, waiting time, and delays, with the degree of benefits showing a decreasing trend with corresponding increases in busload. This finding indicates that CBs with smaller busloads can more flexibly transport passengers and provide a greater level of benefits. At the same time, a small busload strategy can be implemented more easily and in the near future on a test basis in urban China areas.

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Dixon, Andrew E., Anthony D. Lucey, and Peter W. Carpenter. "Optimization of viscoelastic compliant walls for transition delay." AIAA Journal 32, no. 2 (February 1994): 256–67. http://dx.doi.org/10.2514/3.11980.

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Journal articles on the topic 'Delay optimization'

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