Source Reconstruction of Atmospheric Releases with Limited Meteorological Observations Using Genetic Algorithms

A genetic algorithm is paired with a Lagrangian puff atmospheric model to reconstruct the source characteristics of an atmospheric release. Observed meteorological and ground concentration measurements from the real-world Dipole Pride controlled release experiment are used to test the methodology. A sensitivity study is performed to quantify the relative contribution of the number and location of sensor measurements by progressively removing them. Additionally, the importance of the meteorological measurements is tested by progressively removing surface observations and vertical profiles. It is shown that the source term reconstruction can occur also with limited meteorological observations. The proposed general methodology can be applied to reconstruct the characteristics of an unknown atmospheric release given limited ground and meteorological observations.     

Improved retrieval of sea ice total concentration from spaceborne passive microwave observations using numerical weather prediction model fields: An intercomparison of nine algorithms

The accuracy of the sea ice concentration estimates in polar regions is reduced by the effects of atmospheric emission and absorption. A method is presented where a fast atmospheric radiative transfer model and Numerical Weather Prediction (NWP) model fields are used to correct brightness temperatures before they enter the sea ice concentration algorithm. The skill of the method is a function of the errors in the NWP model fields modulated by the sensitivities of the sea ice concentration algorithm used. The NWP model fields representing the most significant atmospheric parameters, i.e. water vapour, cloud liquid water, surface temperature and wind speed over open water are evaluated using remote sensing data. For wind speed and total water vapour, it is found that the standard deviation of the difference is less than the RMS error quoted for the remote sensing algorithms. The best consistency is found for water vapour followed by wind speed. The NWP model cloud liquid water displays standard deviations much higher than the RMS error of the remote sensing algorithm and close to the total average content. Nine sea ice concentration algorithms are further evaluated in a sensitivity study to the above-mentioned atmospheric constituents using a detailed atmospheric radiative transfer model. The result shows that the class of algorithms based solely on the 19 and 37 GHz vertically polarised channels display the smallest sensitivity to all three atmospheric parameters: total water vapour, wind speed and cloud liquid water. Finally, it is demonstrated that this method overcomes many problems associated with conventional weather filtering over mixed ice-water and new-ice pixels and allows the retrieval of sea ice concentrations below 10%.     

基于高层气象大数据的风电场中长期风功率预测研究

针对风电场风电功率波动性强,中长期风功率预测精度不高的问题,本文提出了一种基于高层气象数据的风电场中长期风功率预测方法。首先通过规则化和规范化高层气象数据,找出并完善与风功率强相关的气象因素;其次,结合大气运动方程与和下降梯度方程,建立高层气象数据的演变物理模型;随后,采用大数据聚类和挖掘等算法,对多维度海量高层大气数据进行分类,并基于数据对推导的高层大气数据模型进行训练和修正;最后,基于模型和大数据机器学习方法,构建高层大气运动数据和风电场历史数据之间规律,采用统计分析与物理模型相结合方法,对风电场中长期风功率进行预测。通过结合中国西南某地的风资源数据对某风电场中长期风功率进行预测,证明本文提出的方法能有效提高风电场中长期风功率预测精度。     

移动传感器网络中路径扫描覆盖问题研究

扫描覆盖作为无线传感器网络中的重要应用之一,通过规划移动传感器对区域内兴趣点（POI）进行定期覆盖,因此相较于传统覆盖方法能以更低廉的成本监测POI。研究最少传感器数量-最小罚时路径扫描覆盖问题,即通过调度移动传感器扫描给定路径上的POI集合,使传感器使用数量及产生的POI总罚时成本之和最小。将该问题转换为整数规划,并基于该问题的特殊结构设计贪心算法和遗传算法,以求解大规模实例。在遗传算法基础上引入模拟退火操作,以设计一种遗传模拟退火算法,从而提高求解质量和算法局部寻优能力。实验结果表明,所提贪心算法、遗传算法及遗传模拟退火算法均有较好的收敛性,贪心算法求解质量相对较差,但求解速度快;遗传算法解的质量更好,但存在不稳定的问题,局部寻优能力较弱;遗传模拟退火算法的局部寻优能力和求解稳定性明显增强,解的质量优于其他两种算法。     

Coupling of logistic regression analysis and local search methods for characterization of water distribution system contaminant source

Accidental or intentional drinking water contamination has long been and remains a major threat to water security throughout the world. An inverse problem can be constructed, given sensor measurements in a water distribution system (WDS), to identify the contaminant source characteristics by integrating a WDS simulation model with an optimization method. However, this approach requires numerous compute-intensive simulation runs to evaluate potential solutions; thus, determining the best source characteristic within a reasonable computational time is challenging. In this paper, we describe the development of a WDS contamination characterization algorithm by coupling a statistical model with a heuristic search method. The statistical model is used to identify potential source locations of contamination and a local search aims at further refining contaminant source characteristics. Application of the proposed approach to two illustrative example water distribution networks demonstrates its capability of adaptively discovering contaminant source characteristics as well as evaluating the degree of non-uniqueness of solutions. The results also showed that the local search as an optimizer has better performance than a standard evolutionary algorithm (EA).     

基于STC单片机的气象监测系统的设计与应用

为了较精准地检测多种气象要素,设计了基于STC单片机的气象监测系统。该系统采用光伏离网户用系统进行供电,以STC15W单片机为核心,利用空气质量传感器模组、风速风向传感器以及温湿度传感器对相关气象信息进行在线实时监测;通过串口通信、模数转换、单总线通信读取相应传感器数据;以原厂提供的数据转换公式及滤波算法,换算出各个传感器监测的气象数据,并进行显示。测试结果表明,该系统能够有效监测多个气象要素信息,且稳定性良好,实时性高,监测精度高。     

Achievable accuracy in Gaussian plume parameter estimation using a network of binary sensors

The Gaussian plume model is the core of most regulatory atmospheric dispersion models. The parameters of the model include the source characteristics (e.g. location, strength) and environmental parameters (wind speed, direction, atmospheric stability conditions). The paper presents a theoretical analysis of the best achievable accuracy in estimation of Gaussian plume parameters in the context of a continuous point-source release and using a binary sensor network for acquisition of measurements. The problem is relevant for automatic localisation of atmospheric pollutants with applications in public health and defence. The theoretical bounds of achievable accuracy provide a guideline for sensor network deployment and its performance under various environmental conditions. The bounds are compared with empirical errors obtained using a Markov chain Monte Carlo (MCMC) parameter estimation technique.     

Information-driven receptor placement for contaminant source determination

Isolating the source of an unknown contaminant emission is a challenging problem when provided with only a limited and noisy set of mean concentration measurements. A Bayesian approach to this inverse problem yields estimates for the source parameters (location and strength) which depend directly on the quality of the information obtained from an array of detectors. If the data are of poor quality, uncertainties associated with the source parameter estimates may be large, necessitating further exploration (e.g., using mobile detection) in order to better isolate the putative source. We employ Bayesian experimental design with the goal of strategically placing an additional detector in order to maximize the ‘expected information’ contained in subsequent posterior distributions for the source parameters. The methodology is demonstrated using synthetic data from detectors lying in a horizontally homogeneous, neutrally-stratified atmospheric surface layer. Markov chain Monte Carlo and a posterior sampling technique are used to calculate the expected information over a grid of potential detector locations, and an auxiliary detector measuring both mean concentration and turbulent scalar fluxes is added where the expected information reaches a maximum. The updated posterior distribution (calculated based on the additional measurements) yields significantly improved estimates for the source location and strength.     

A link between dispersion models and monitoring data: The estimate of source term

An important application of real-time atmospheric dispersion models is the link between model results and field measurements to achieve an estimate of the source term of a continous realease. In this paper a method for the evaluation of the emission rate (STEP: Source Term Estimate Program) is presented. STEP doesn't depend on the dispersion model used and is based on few, simple considerations about the cause of the commonly observed scatter between measured and computed concentration values at fixed sample points. The results of two STEP tests are presented: firstly, it has been validated against a set of tracer data collected during two meteorological and diffusion campaigns; secondly, a sensitivity study with respect to meteorological parameters and to the number of monitoring data available was carried out.     

具有提前ö拖期惩罚的热轧钢管批调度问题研究

建立了具有提前／拖期惩罚的热轧钢管批调度问题的混合整数非线性规划模型，提出并证明了给定合同排序下的最优组批方式，从而将原问题转化为易求解的合同排序问题．同时，建立了转化问题的数学模型并设计了遗传算法．仿真实验验证了模型和算法的有效性．     

The reduced cost branch and bound algorithm for mixed integer programming

A different branch and bound algorithm for mixed integer programming is presented. Unlike standard linear programming based branch and bound algorithms, where a single fractional variable (or Special Ordered Set) is selected for problem separation, the proposed method selects groups of variables for separation on the basis of their reduced cost in an LP relaxation. The proposed method restricts a large portion of the integer variables to zero on one branch. The net effect is that the original integer program is solved by optimizing a series of smaller, more tightly restricted, integer programs. The authors have programmed the algorithm using the Extended Control Language of the IBM MPSX/370-MIP/370 mixed integer programming package. Computational results are presented that demonstrate the efficiency of the method on problems where the $\text{0}\text{1}$ variables are partitioned into multiple choice constraints containing special ordered sets of variables. While the computational results are limited to this class of problems the algorithm can, in theory, be applied to any mixed integer programming problem.     

GPS模拟器在无人机仿真中的设计与应用

为模拟无人机在真实大气环境下,存在风场干扰以及传感器存在误差条件下的导航控制,设计出一种GPS模拟器,简化了风模型和紊流模型,给出了GPS模拟器的设计思路以及在传感器偏差与常值风干扰下的设计原理;最后利用常值风干扰仿真,验证了风场估计算法的正确性;仿真表明,用矢量三角形估计法将常值风场与传感器误差模型估计出来后得到的风场数据修正航程推算,提高定位精度达到了较好的控制效果;该GPS模拟器可以为无人机仿真系统提供闭环控制条件,能够很好地模拟无人机在真实大气环境中的导航与制导控制,具有一定的实用价值。     

Meteorological effects on sulphur dioxide concentrations on the area of Turbigo

This paper presents the relationship between meteorological parameters and sulphur dioxide concentrations in the area of Turbigo. A large number of sulphur dioxide sources are located in this area: they are both urban and industrial emissions. Mean half hourly SO₂ measurements were recorded over a three year period at five monitoring stations. Meteorological data were taken by a meteorological station in this network and included mean halfhourly measurements of wind direction and speed, air temperature, atmospheric pressure, relative humidity and rainfall. The SO₂ data were classified by the meteorological parameters, singly and in combination. From the analysis of the effects of various meteorological parameters, wind direction was found to be the parameter best correlated with pollution concentration. Additional results regarding the seasonal cycles of pollution levels are also presented. The work is also based on a set of statistical and graphic techniques.     

Scheduling prioritized patients in emergency department laboratories

This research focuses on scheduling patients in emergency department laboratories according to the priority of patients’ treatments, determined by the triage factor. The objective is to minimize the total waiting time of patients in the emergency department laboratories with emphasis on patients with severe conditions. The problem is formulated as a flexible open shop scheduling problem and a mixed integer linear programming model is proposed. A genetic algorithm (GA) is developed for solving the problem. Then, the response surface methodology is applied for tuning the GA parameters. The algorithm is tested on a set of real data from an emergency department. Simulation results show that the proposed algorithm can significantly improve the efficiency of the emergency department by reducing the total waiting time of prioritized patients.     

A Receding Horizon Control algorithm for adaptive management of soil moisture and chemical levels during irrigation

The capacity to adaptively manage irrigation and associated contaminant transport is desirable from the perspectives of water conservation, groundwater quality protection, and other concerns. This paper introduces the application of a feedback-control strategy known as Receding Horizon Control (RHC) to the problem of irrigation management. The RHC method incorporates sensor measurements, predictive models, and optimization algorithms to maintain soil moisture at certain levels or prevent contaminant propagation beyond desirable thresholds. Theoretical test cases are first presented to examine the RHC scheme performance for the control of soil moisture and nitrate levels in a soil irrigation problem. Then, soil moisture control is successfully demonstrated for a center-pivot system in Palmdale, CA where reclaimed water is used for agricultural irrigation. Real-time soil moisture, temperature, and meteorological data were streamed wirelessly to a field computer to enable autonomous execution of the RHC algorithm. The RHC scheme is demonstrated to be a viable strategy for achieving water reuse and agricultural objectives while minimizing negative impacts on environmental quality.     

Source term estimation of a hazardous airborne release using an unmanned aerial vehicle

Gaining information about an unknown gas source is a task of great importance with applications in several areas, including responding to gas leaks or suspicious smells, quantifying sources of emissions, or in an emergency response to an industrial accident or act of terrorism. In this paper, a method to estimate the source term of a gaseous release using measurements of concentration obtained from an unmanned aerial vehicle (UAV) is described. The source term parameters estimated include the three‐dimensional location of the release, its emission rate and other important variables needed to forecast the spread of the gas using an atmospheric transport and dispersion model. The parameters of the source are estimated by fusing concentration observations from a gas detector on‐board the aircraft, with meteorological data and an appropriate model of dispersion. Two models are compared in this paper, both derived from analytical solutions to the advection–diffusion equation. Bayes’ theorem, implemented using a sequential Monte Carlo algorithm, is used to estimate the source parameters to take into account the large uncertainties in the observations and formulated models. The system is verified with novel, outdoor, fully automated experiments, where observations from the UAV are used to estimate the parameters of a diffusive source. The estimation performance of the algorithm is assessed subject to various flight path configurations and wind speeds. Observations and lessons learned during these unique experiments are discussed, and areas for future research are identified.     

一种基于遗传算法的无线传感器网络节点优化方法

针对基于无线传感器网络的测控系统的特殊性,提出了在满足测控节点连通约束条件下使节点数量最少的模型,并采用遗传算法进行优化计算.为了提高节点多时的收敛速度,提出了基于二分法的遗传算法,结果表明该算法可以大大减少染色体长度.提高优化收敛速度,最后给出了实例.     

基于HGA的冲压车间生产计划与调度的集成优化

根据车身厂冲压车间和生产库房的实际情况,研究了冲压件成批生产的Job-shop车间生产计划和调度的集成优化问题,给出该问题的非线性混合整数规划模型,并采用混合遗传算法进行求解。遗传算法中,给出一种新的启发式规则来改善初始解集,通过与递阶分解方法进行比较,得出该算法对求解该类问题有着很好的效果。     

Evolutionary induction of stochastic context free grammars

This paper describes an evolutionary approach to the problem of inferring stochastic context-free grammars from finite language samples. The approach employs a distributed, steady-state genetic algorithm, with a fitness function incorporating a prior over the space of possible grammars. Our choice of prior is designed to bias learning towards structurally simpler grammars. Solutions to the inference problem are evolved by optimizing the parameters of a covering grammar for a given language sample. Full details are given of our genetic algorithm (GA) and of our fitness function for grammars. We present the results of a number of experiments in learning grammars for a range of formal languages. Finally we compare the grammars induced using the GA-based approach with those found using the inside-outside algorithm. We find that our approach learns grammars that are both compact and fit the corpus data well.