scholarly journals An Improved Shuffled Frog Leaping Algorithm and Its Application in Dynamic Emergency Vehicle Dispatching

2018 ◽  
Vol 2018 ◽  
pp. 1-34 ◽  
Author(s):  
Xiaohong Duan ◽  
Tianyong Niu ◽  
Qi Huang
Keyword(s):  
Real Time ◽  
Prediction Error ◽  
Travel Speed ◽  
Time Dependent ◽  
Emergency Vehicle ◽  
Shuffled Frog Leaping Algorithm ◽  
The Real ◽  
Vehicle Dispatching ◽  
Selection Strategies ◽  
Shuffled Frog Leaping

The traditional method for solving the dynamic emergency vehicle dispatching problem can only get a local optimal strategy in each horizon. In order to obtain the dispatching strategy that can better respond to changes in road conditions during the whole dispatching process, the real-time and time-dependent link travel speeds are fused, and a time-dependent polygonal-shaped link travel speed function is set up to simulate the predictable changes in road conditions. Response times, accident severity, and accident time windows are taken as key factors to build an emergency vehicle dispatching model integrating dynamic emergency vehicle routing and selection. For the unpredictable changes in road conditions caused by accidents, the dispatching strategy is adjusted based on the real-time link travel speed. In order to solve the dynamic emergency vehicle dispatching model, an improved shuffled frog leaping algorithm (ISFLA) is proposed. The global search of the improved algorithm uses the probability model of estimation of distribution algorithm to avoid the partial optimal solution. Based on the Beijing expressway network, the efficacy of the model and the improved algorithm were tested from three aspects. The results have shown the following: (1) Compared with SFLA, the optimization performance of ISFLA is getting better and better with the increase of the number of decision variables. When the possible emergency vehicle selection strategies are 815, the objective function value of optimal selection strategies obtained by the base algorithm is 210.10% larger than that of ISFLA. (2) The prediction error of the travel speed affects the accuracy of the initial emergency vehicle dispatching. The prediction error of ±10 can basically meet the requirements of the initial dispatching. (3) The adjustment of emergency vehicle dispatching strategy can successfully bypassed road sections affected by accidents and shorten the response time.

scholarly journals Emergency Vehicle Dispatching and Redistribution in Highway Network Based on Bilevel Programming

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Xiaohong Duan ◽  
Shouxin Song ◽  
Jiandong Zhao
Keyword(s):  
Bilevel Programming ◽  
Programming Model ◽  
Time Windows ◽  
Emergency Vehicle ◽  
Shuffled Frog Leaping Algorithm ◽  
Coverage Area ◽  
Vehicle Dispatching ◽  
Emergency Vehicles ◽  
Shuffled Frog Leaping ◽  
Bilevel Programming Model

Response time is a key factor in the emergency vehicle dispatching problem. Because regional emergency vehicles are limited, vehicle gaps will be created in the rescue station after vehicles are dispatched to several accidents, which affects quick response to the subsequent incidents. To solve this problem, a bilevel programming model for emergency vehicle dispatching and redistribution is established, of which the optimal objectives are the shortest rescue time for current accidents and the shortest time for vehicle redistribution, and the key constraints are emergency vehicle requirements and accident time windows. In the precondition of effective rescue of current accidents, emergency vehicles are redistributed according to the potential risks in the rescue station coverage area. A bilevel shuffled frog leaping algorithm is proposed to solve the bilevel programming model. The dispatching results of examples show that the model conforms to dispatching decision rule and the bilevel shuffled frog leaping algorithm can resolve the bilevel programming model fast and efficiently.

scholarly journals Improving Ensemble Forecasting Using Total Least Squares and Lead-Time Dependent Bias Correction

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 300 ◽  
Author(s):  
Aida Jabbari ◽  
Deg-Hyo Bae
Keyword(s):  
Least Squares ◽  
Real Time ◽  
Bias Correction ◽  
Lead Time ◽  
Weather Prediction ◽  
Total Least Squares ◽  
Time Dependent ◽  
Precipitation Forecast ◽  
Post Processing ◽  
The Real

Numerical weather prediction (NWP) models produce a quantitative precipitation forecast (QPF), which is vital for a wide range of applications, especially for accurate flash flood forecasting. The under- and over-estimation of forecast uncertainty pose operational risks and often encourage overly conservative decisions to be made. Since NWP models are subject to many uncertainties, the QPFs need to be post-processed. The NWP biases should be corrected prior to their use as a reliable data source in hydrological models. In recent years, several post-processing techniques have been proposed. However, there is a lack of research on post-processing the real-time forecast of NWP models considering bias lead-time dependency for short- to medium-range forecasts. The main objective of this study is to use the total least squares (TLS) method and the lead-time dependent bias correction method—known as dynamic weighting (DW)—to post-process forecast real-time data. The findings show improved bias scores, a decrease in the normalized error and an improvement in the scatter index (SI). A comparison between the real-time precipitation and flood forecast relative bias error shows that applying the TLS and DW methods reduced the biases of real-time forecast precipitation. The results for real-time flood forecasts for the events of 2002, 2007 and 2011 show error reductions and accuracy improvements of 78.58%, 81.26% and 62.33%, respectively.

Active Control of Non-Linear System by a Fuzzy-Optimal Control Technique

2010 ◽  
Author(s):  
Takashi Mochio
Keyword(s):  
Optimal Control ◽  
Nonlinear System ◽  
Control Theory ◽  
Real Time ◽  
Active Control ◽  
Optimal Control Theory ◽  
Time Dependent ◽  
Control Technique ◽  
The Real ◽  
Non Linear System

The purpose of this paper is to estimate the real time vibration control of an actively-controlled nonlinear structure due to non-stationary external loads. When the optimal control theory is adopted as a control law against the concerned task, the derivation of time dependent optimal control gains may be required because of a remarkable non-stationarity of response amplitude. In addition, since the system is nonlinear, it takes more time to calculate those time dependent gains. This means that it is difficult to strictly execute the real time active control with optimal control theory as for the non-stationary and nonlinear system. In this paper, therefore, one approximate technique, coupled fuzzy-optimal control, is proposed in order to realize the real time control of non-stationary and nonlinear system. Finally, results by deterministic analysis based on numerical simulations are compared with those by stochastic analysis using statistical equivalent linearization technique.

Time-dependent FTIR microscopy for mechanism investigations and kinetic measurements in interfacial polymerisation: a microporous polymer film study

2019 ◽  
Vol 10 (22) ◽  
pp. 2769-2773 ◽  
Author(s):  
Dan Ren ◽  
Jet Ing Ngie Yeo ◽  
Tian-Yin Liu ◽  
Xiaolin Wang
Keyword(s):  
Reaction Kinetics ◽  
Polymer Film ◽  
Real Time ◽  
Interfacial Polymerization ◽  
Time Dependent ◽  
Ftir Microscopy ◽  
Kinetic Measurements ◽  
The Real ◽  
Film Study ◽  
Microporous Polymer

The real-time characterisation of interfacial polymerization is demonstrated by using FTIR-mapping spectroscopy with microscopy to deduce the reaction kinetics.

scholarly journals Edge effect detection for real-time cellular analyzer using statistical analysis

RSC Advances ◽  
2017 ◽  
Vol 7 (34) ◽  
pp. 20833-20839 ◽  
Author(s):  
Yinghao Chen ◽  
Shan Chen ◽  
Tianhong Pan ◽  
Xiaobo Zou
Keyword(s):  
Statistical Analysis ◽  
Real Time ◽  
Edge Effect ◽  
Cellular Response ◽  
Time Dependent ◽  
Response Curves ◽  
The Real ◽  
Valid Time ◽  
Smirnov Test

The Smirnov test is used to detect the edge effect, which can help technicians rapidly screen valid time-dependent cellular response curves (TCRCs) in the real time cellular analyzers (RTCA).

Sign in / Sign up

Export Citation Format

Share Document