A Partial Parallel Airport Gate Assignment Supported by a Knowledge－based System Combined with Mathematical Programming

The gate assignment at an airport is one of the major activities in airport operations.With the increase of passenger traffic volumes and the number of flights, the complexity of this task and the factors to be considered have increased significantly, and an efficient gate utilizationhas received considerable attention. For overcoming the shortcomings of previous gate assignmentapproaches, this paper presents a partial parallel gate assignment approach, by which more factorsconcerning aircraft and gates can be collsidered at the same time. This paper also presents themethod of using a knowledge-based system combined with a mathematical programming method forgetting an optimized feasible assignment solution. By this way, it is more easily to get the solutionthat satisfies both the static and dynamic situations,and thus it may adapt well to meet the needsof actual use to rea-time operations. An experimental prototype has been implemented, and a casestudy is presented at the end of the paper.

Research on Flight First Service Model and Algorithms for the Gate Assignment Problem

Aiming at the problem of gate allocation of transit flights,a flight first service model is established.Under the constraints of maximizing the utilization rate of gates and minimizing the transit time,the idea of“first flight serving first”is used to allocate the first time,and then the hybrid algorithm of artificial fish swarm and simulated annealing is used to find the optimal solution.That means the fish swarm algorithm with the swallowing behavior is employed to find the optimal solution quickly,and the simulated annealing algorithm is used to obtain a global optimal allocation scheme for the optimal local region.The experimental data show that the maximum utilization of the gate is 27.81%higher than that of the“first come first serve”method when the apron is not limited,and the hybrid algorithm has fewer iterations than the simulated annealing algorithm alone,with the overall passenger transfer tension reducing by 1.615;the hybrid algorithm has faster convergence and better performance than the artificial fish swarm algorithm alone.The experimental results indicate that the hybrid algorithm of fish swarm and simulated annealing can achieve higher utilization rate of gates and lower passenger transfer tension under the idea of“first flight serving first”.

Airport gate assignment problem with deep reinforcement learning

With the rapid development of air transportation in recent years,airport operations have attracted a lot of attention.Among them,airport gate assignment problem(AGAP)has become a research hotspot.However,the real-time AGAP algorithm is still an open issue.In this study,a deep reinforcement learning based AGAP(DRL-AGAP)is proposed.The optimization object is to maximize the rate of flights assigned to fixed gates.The real-time AGAP is modeled as a Markov decision process(MDP).The state space,action space,value and rewards have been defined.The DRL-AGAP algorithm is evaluated via simulation and it is compared with the flight pre-assignment results of the optimization software Gurobiand Greedy.Simulation results show that the performance of the proposed DRL-AGAP algorithm is close to that of pre-assignment obtained by the Gurobi optimization solver.Meanwhile,the real-time assignment ability is ensured by the proposed DRL-AGAP algorithm due to the dynamic modeling and lower complexity.

MULTI-OBJECTIVE PROGRAMMING FOR AIRPORT GATE REASSIGNMENT

To improve the efficiency of gate reassignment and optimize the plan of gate reassignment,the concept of disruption management is introduced,and a multi-objective programming model for airport gate reassignment is proposed.Considering the interests of passengers and the airport,the model minimizes the total flight delay,the total passengers′walking distance and the number of flights reassigned to other gates different from the planned ones.According to the characteristics of the gate reassignment,the model is simplified.As the multi-objective programming model is hard to reach the optimal solutions simultaneously,a threshold of satisfactory solutions of the model is set.Then a simulated annealing algorithm is designed for the model.Case studies show that the model decreases the total flight delay to the satisfactory solutions,and minimizes the total passengers′walking distance.The least change of planned assignment is also reached.The results achieve the goals of disruption management.Therefore,the model is verified to be effective.

Quality Assurance for Respiratory-Gated Radiotherapy Using the Real-Time Tumor-Tracking Radiotherapy System

Purpose: Respiratory-gated radiation therapy (RT) using the real-time tumor-tracking radiotherapy (RTRT) system is an effective technique for managing tumor motion. High dosimetric and geometric accuracy is needed;however, quality assurance (QA) for respiratory-gated RT using the RTRT system has not been reported. The purpose of this study was to perform QA for respiratorygated RT using the RTRT system. Materials and Methods: The RTRT system detected the position of the fiducial marker and radiation delivery gated to the motion of the marker was performed. The dynamic anthropomorphic thorax phantom was positioned at the isocenter using the fiducial marker in the phantom. The phantom was irradiated only when the fiducial marker was within a three-dimensional gating window of ±2 mm from the planned position. First, the absolute doses were measured using anionization chamber inserted in the phantom under the stationary, gating and non-gating state for sinusoidal (nadir-to-peak amplitude [A]: 20 - 40 mm, breathing period [T]: 2 - 4 s) and the basic respiratory patterns. Second, the dose profiles were measured using Gafchromic films in the phantom under the same conditions. Differences between dose profiles were calculated to evaluate the dosimetric and geometric accuracy. Finally, differences between the actual and measured position of the fiducial marker were calculated to evaluate the tracking accuracy for sinusoidal and basic respiratory patterns. Results: For the sinusoidal patterns, the relative doses were 0.93 for non-gating and 0.99 for gating (A = 20 mm, T = 2 s), 0.94 for non-gating and 1.00 for gating (A = 20 mm, T = 4 s), 0.55 for non-gating and 1.00 for gating (A = 40 mm, T = 4 s), respectively. For the basic respiratory pattern, the relative doses were 1.00 for non-gating and 1.00 for gating, respectively. Compared to the stationary conditions, the differences in lateral distance between the 90% dose of dose profiles were 6.23 mm for non-gating and 0.36 mm for gating (A = 20 mm, T = 2 s), 8.79 mm for non-gating and 1.73 mm for gating (A = 20 mm, T = 4 s), 18.37 mm for non-gating and 0.67 mm for gating (A = 40 mm, T = 4 s), respectively. For the basic respiratory pattern, those were 5.23 mm for non-gating and 0.35 mm for gating. The root mean square (RMS) values of the tracking error were 0.18 mm (A = 20 mm, T = 2 s), 0.14 mm (A = 20 mm, T = 4 s), and 0.21 mm (A = 40 mm, T = 4 s) for sinusoidal and 0.79 mm for the basic respiratory pattern, respectively. Conclusion: We conducted QA for respiratory-gated RT using the RTRT system. The respiratory-gated RT using the RTRT system reduced the blurring effects on dose distribution with high dosimetric and geometric accuracy.

A greedy algorithm based on joint assignment of airport gates and taxiways in large hub airports

With the rapid development of civil aviation in recent years,the management and assignment of airport resources are becoming more and more difficult.Among the various airport resources,gates and taxiways are very important,therefore,many researchers focus on the airport gate and taxiway assignment problem.However,the joint assignment algorithm of airport gates and taxiways with realistic airport data has not been well studied.A greedy algorithm based on joint assignment of airport gates and taxiways using the data of a large hub airport in China is proposed.The objective is maximizing the ratio of fixed gates and minimizing the ratio of taxiway collisions.Simulation results show that it outperforms other assignment schemes.

High Accuracy and Real-Time Gated Viewing Laser Radar

A gated viewing laser radar has an excellent performance in underwater low light level imaging, and it also provides a viable solution to inhibit backscattering. In this paper, a gated viewing imaging system according to the demand for real-time imaging is presented, and then the simulation is used to analyze the performance of the real-time gated viewing system. The range accuracy performance is limited by the slice number, the width of gate, the delay time step, the initial delay time, as well as the system noise and atmospheric turbulence. The simulation results indicate that the highest range accuracy can be achieved when the system works with the optimal parameters. Finally, how to choose the optimal parameters has been researched.

Assigning Real-Time Tasks in Environmentally Powered Distributed Systems

Harvesting energy for execution from the environment (e.g., solar, wind energy) has recently emerged as a feasible solution for low-cost and low-power distributed systems. When real-time responsiveness of a given application has to be guaranteed, the recharge rate of obtaining energy inevitably affects the task scheduling. This paper extends our previous works in?[1] [2] to explore the real-time task assignment problem on an energy-harvesting distributed system. The solution using Ant Colony Optimization (ACO) and several significant improvements are presented. Simulations compare the performance of the approaches, which demonstrate the solutions effectiveness and efficiency.

High performance reconfigurable hardware system for real-time image processing

A novel reconfigurable hardware system which uses both muhi-DSP and FPGA to attain high performance and real-time image processing are presented. The system structure and working principle of mainly processing multi-BSP board, extended multi-DSP board are analysed. The outstanding advantage is that the communication among different board components of this system is supported by high speed link ports ＆ serial ports for increasing the system performance and computational power. Then the implementation of embedded real-time operating systems （RTOS） by us is discussed in detail. In this system, we adopt two kinds of parallel structures controlled by RTOS for parallel processing of algorithms. The experimental results show that exploitive period of the system is short, and maintenance convenient. Thus it is suitable for real-time image processing and can get satisfactory effect of image recognition.

Real-Time Upstream Services Demonstration in Orthogonal Frequency Division Multiplexing- Passive Optical Network System

Abstract： Real-time digital service and mul- timedia service upstream transmission in Dig- ital Signal Processing （DSP）-based Orthogo- nal Frequency Division Multiplexing-Passive Optical Network （OFDM-PON） is experimen- tally demonstrated with Centralised Light Sou- rce （CLS） configuration in this paper. After transmitted over 25 km Standard Single Mode Fibre （SSMF） with -16.5 dBm optical power at receiver, the Bit Error Rate （BER） is 9.5 ×10^-11. The implementations of digital domain up-conversion and down-conversion based on Field Programmable Gate Array （FPGA） are int- roduced, which can reduce the cost of In-ph- ase and Quadrature （IQ） radio frequency mix- ers utilised at transmitter and receiver. A car- rier synchronization algorithm is implemented for compensating carrier offset. A channel eq- ualization algorithm is adopted for compen- sating the damage of channel. A new structure of Frequency Synchronization Unit （FSU） des- igned in FPGA is also proposed to cope with the frequency shifting at receiver.

考虑候机区拥挤的机场廊桥再分配优化研究

为缓解高峰时段机场候机厅内局地过度拥挤现象,对既有廊桥分配方案进行再优化,构建数学优化模型,以最小化各登机口候机区域客流密度最大值为目标,综合考虑停机位预分配方案、前后航班及相邻登机口航班时刻、候机厅面积等约束,在不影响廊桥利用率的前提下,优化候机区客流时空分布,避免因局地过度拥挤而诱增潜在的管理风险。鉴于模型的计算复杂性,运用遗传算法进行优化求解。实例计算结果显示:算法收敛性能良好;优化后候机区内局地的客流密度峰值下降近50%,候机厅资源利用均衡性明显改善,对应均方差指标降幅超过51%,表明所提方法实现了预期效果,可提升机场运行管理水平和服务质量。

机场停机位分配问题研究现状与展望

为提高机场场面资源利用效率,大量文章研究停机位分配问题的优化模型与求解算法。首先,概述了停机位分配问题概念。其次,从旅客、机场、航空公司和鲁棒性等不同维度,梳理了停机位分配问题优化目标的研究现状,并归纳了停机位分配问题的约束条件。从数学规划法、智能优化法两个维度综述了停机位分配问题的求解算法,并比较了不同算法优缺点。最后,从考虑交互关系的多目标优化、实现动态实时分配、多资源联合分配、创新优化算法和考虑不确定因素五个方面展望了停机位分配问题研究的发展趋势。

Robust Assignment of Airport Gates with Operational Safety Constraints

This paper reviews existing approaches to the airport gate assignment problem （AGAP） and presents an optimization model for the problem considering operational safety constraints. The main objective is to minimize the dispersion of gate idle time periods （to get robust optimization） while ensuring appropriate matching between the size of each aircraft and its assigned gate type and avoiding the potential hazard caused by gate apron operational conflict. Genetic algorithm is adopted to solve the problem, An illustrative example is given to show the effectiveness and efficiency of the algorithm. The algorithm performance is further demonstrated using data of a terminal from Beijing Capital International Airport （PEK）.

基于启发式算法的停机位分配研究

针对当前机场停机位资源紧张以及航班延误等问题,本文研究了机场停机位资源分配问题。首先,依据机场停机位资源分配的相关规定,将其转化为目标函数和约束条件,构建了以最小化停机位使用的整数规划模型。其次,考虑飞机与停机位属性匹配的问题,提出了基于属性匹配的启发式算法,对停机位分配问题进行求解。最后,通过使用CPLEX软件对小规模问题进行精确的求解,以验证模型的准确性,并应用启发式算法对某机场的大规模分配问题进行研究。实验结果表明,本文构建的模型和算法能有效应对机场现实运营中的停机位分配问题,且效果良好。

基于排序算法的机场停机位分配问题研究

停机位分配作业关系到整个机场的系统运作,其作用相当重要。通过分析航班占用停机位的特性,建立停机位分配问题的排序模型,然后考虑"先到先服务"的规则并通过引入机位标号函数和航班标号函数设计一种求解模型的标号算法,该算法的计算复杂性为O(nm),最后将该算法应用于一个算例,说明该算法为利用计算机进行停机位自动分配并优化停机位结果提供了一种可行手段。

机场登机口优化调度算法及实证

在图论的基础上建立了旅客登机口优化安排的网络模型,给出了它的优化算法。考虑到在登机口调度的实际运作中存在着飞机停场的时间限制、"航班对"的限制和机型与登机口的匹配等限制,提出了该理论模型在使用中的实用算法,并用首都机场18个登机口优化安排334个航班的例子证实了这种算法在缩短旅客步行距离和提高设施利用率方面的显著效果。该算法也可以用于到港飞机停靠廊桥的优化安排,以减少旅客从廊桥到行李房步行的总距离。

一种新的停机位分配优化模型

针对国内机场目前基本依据经验分配停机位的情况,基于传统滑行路径的理念,建立了降低旅客进出机场飞行区时间的停机位分配模型.在满足场面运行安全约束及可接受延误水平下,寻求时间最小的分配方案.通过机场的地面网络数据、运行模式以及航班计划等信息,利用计算机仿真对模型进行了算法设计,并利用MATLAB编程进行了计算,与机场地面容量评估系统(ACES)中的停机位随机分配模型进行了对比.结果显示:与随机分配模型相比,旅客飞行区平均停留时间减少9.7%,机场地面容量提高5.7%,冲突次数和延误时间分别降低9.4%、6.4%.因此,机场运行效率与资源配置情况得到改善,所提模型与算法有效.

机场停机位指派模型及算法

为探索中小型机场停机位指派问题有效合理的解决方法,以乘客最小行走距离为优化目标,建立了中小型机场停机位整数规划指派模型,利用改进的启发式算法进行了求解。该算法可以缩小搜索空间,在最坏情况下的计算复杂度是多项式的,优于CPLEX软件的指数级计算复杂度,具有更高的计算效率;与CPLEX结果相比,距离误差仅为5.2%,指派结果令人满意。

基于航空排放的机场停机位分配优化

随着航空业的快速发展,航空排放对大气环境的影响日益严重。机场停机位分配优化研究,对航空绿色发展具有重要意义。基于场面运行规则,航空器排放、近机位利用率等多目标,建立一种使航空器排放量最小,近机位利用率最大的机场停机位分配优化模型,并通过南京禄口国际机场某日航班数据实例验证。结果表明:由于近机位利用率的提升,航空器的HC、NO x、CO、SO x和颗粒物(particulate matter,PM)排放量分别减少12.33%、7.81%、12.66%、11.06%和11.17%;地面保障设备(ground support equipment,GSE)的HC、NO x、CO、PM排放量分别减少9.59%、4.63%、14.34%、13.64%;远机位旅客平均花费时间减少42.31%。可见提出的优化模型增加了近机位利用率,减少了机场航空排放,减少了远机位旅客平均花费时间,验证了模型有效性。

民用机场停机位优化配置

停机位配置指为到港或离港航班指定适宜的登机口,确保航班正点。航班停机位的高效、合理安排是机场地面作业中的一项核心任务。本文在系统分析国内繁忙机场停机位配置情况的基础上,提出以旅客登转机时间(旅客满意度)、机型与停机位类型匹配(机场效益)为优化目标,同时考虑航班类型(国内短途、国际长途)、航班数量与密度(忙时、闲时)、停机时间的停机位配置的数学模型,并设计求解模型的禁忌搜索(TS)算法。数值仿真证明了模型和算法的有效性。