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Prediction of credit risk with an ensemble model: a correlation-based classifier selection approach

JOURNAL OF MODELLING IN MANAGEMENT 2022年第4期17卷 1078-1097页

作者： Xiong, Zhibin Huang, Jun South China Normal Univ Shipai Campus Sch Math Sci Guangzhou Peoples R China Angelo State Univ Dept Management & Mkt San Angelo TX 76909 USA

Purpose Ensemble models that combine multiple base classifiers have been widely used to improve prediction performance in credit risk evaluation. However, an arbitrary selection of base classifiers is problematic. The purpose of this paper is to develop a framework for selecting base classifiers to improve the overall classification performance of an ensemble model. Design/methodology/approach In this study, selecting base classifiers is treated as a feature selection problem, where the output from a base classifier can be considered a feature. The proposed correlation-based classifier selection using the maximum information coefficient (MIC-CCS), a correlation-based classifier selection under the maximum information coefficient method, selects the features (classifiers) using nonlinear optimization programming, which seeks to optimize the relationship between the accuracy and diversity of base classifiers, based on MIC. Findings The empirical results show that ensemble models perform better than stand-alone ones, whereas the ensemble model based on MIC-CCS outperforms the ensemble models with unselected base classifiers and other ensemble models based on traditional forward and backward selection methods. Additionally, the classification performance of the ensemble model in which correlation is measured with MIC is better than that measured with the Pearson correlation coefficient. Research limitations/implications The study provides an alternate solution to effectively select base classifiers that are significantly different, so that they can provide complementary information and, as these selected classifiers have good predictive capabilities, the classification performance of the ensemble model is improved. Originality/value This paper introduces MIC to the correlation-based selection process to better capture nonlinear and nonfunctional relationships in a complex credit data structure and construct a novel nonlinear programming model for base classifiers select

关键词： Risk analysis nonlinear programming Modeling Data analytics Credit risk prediction Ensemble model Correlation-based classifier selection Maximum information coefficient nonlinear optimization

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Minimum-lap-time optimisation and simulation

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VEHICLE SYSTEM DYNAMICS 2021年第7期59卷 1069-1113页

作者： Massaro, M. Limebeer, D. J. N. Univ Padua Dept Ind Engn Padua Italy Univ Johannesburg Dept Elect & Elect Engn Sci Johannesburg South Africa

The paper begins with a survey of advances in state-of-the-art minimum-time simulation for road vehicles. The techniques covered include both quasi-steady-state and transient vehicle models, which are combined with trajectories that are either pre-assigned or free to be optimised. The fundamentals of nonlinear optimal control are summarised. These fundamentals are the basis of most of the vehicular optimal control methodologies and solution procedures reported in the literature. The key features of three-dimensional road modelling, vehicle positioning and vehicle modelling are also summarised with a focus on recent developments. Both cars and motorcycles are considered.

关键词： Lap-time simulation optimisation road modelling quasi-steady-state optimal control nonlinear programming g-g map free-trajectory Formula One MotoGP NASCAR

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Optimization of start-up operation for centrifugal chiller 18

Optimization of start-up operation for centrifugal chiller

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18th IFAC Workshop on Control Applications of Optimization (CAO)

作者： Okazaki, Hirotaka Ono, Hitoi Yanai, Noritaka Mitsubishi Heavy Ind Co Ltd Kobe Hyogo Japan

In this study, we derived an operating profile that minimizes startup time using a rigorous physical model that takes into account the characteristics of the compressors and heat exchangers that make up a centrifugal chiller, as well as the phase change and flow of the refrigerant. As an optimization method, we used the direct method of transforming the original infinite optimal control problem into a finite-dimensional nonlinear programming problem. We were able to derive an operation profile that reduces the startup time while satisfying the constraints compared to conventional operations and confirmed that the model and optimization method are effective for optimal design of equipment and control logic. Copyright (C) 2022 The Authors.

关键词： Optimal control nonlinear programming Physical models Sequential control Function approximation Differential algebraic equations Dynamic optimization

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Collaborative transmit resource scheduling and waveform selection for target tracking in multistatic radar system

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IET RADAR SONAR AND NAVIGATION 2021年第3期15卷 209-225页

作者： Wang, Yijie Shi, Chenguang Wang, Fei Zhou, Jianjiang Nanjing Univ Aeronaut & Astronaut Key Lab Radar Imaging & Microwave Photon Minist Educ Nanjing 210016 Peoples R China Sci & Technol Electroopt Control Lab Luoyang Peoples R China

This paper proposes a collaborative transmit resource scheduling and waveform selection (CTRSWS) strategy for target tracking in multistatic radar system which consists of one transmitter and an arbitrary number of receivers. The main mechanism of the proposed CTRSWS strategy is to exploit the optimisation technique to jointly optimise the illumination power, dwell time, waveform bandwidth, and pulse length under the constraints of several resource budgets and the predefined waveform library, aiming at improving the low probability of intercept (LPI) performance and target tracking accuracy of multistatic radar system simultaneously. The analytical expressions for the probability of intercept and the trace of the predicted error covariance matrix corresponding to the target state estimation are derived and adopted to evaluate the LPI performance and target tracking accuracy, respectively. Subsequently, the resulting non-convex and non-linear optimisation problem is resolved by an efficient and fast four-stage solution methodology. Several numerical results are provided to verify the effectiveness and superiority of the proposed CTRSWS scheme in terms of the achievable LPI performance and target tracking accuracy of multistatic radar system.

关键词： concave programming covariance matrices nonlinear programming probability radar tracking state estimation target tracking telecommunication scheduling

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Model-optimization-guided neural network (MOGNN) applied to chemical processes

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APPLIED SOFT COMPUTING 2024年 167卷

作者： Siqueira, Felipe Macedo Freitas de Sousa Santos, Lizandro Univ Fed Fluminense Dept Chem & Petr Engn Rua Passo Patria 156 BR-24210240 Niteroi RJ Brazil

In this work, a Model-Optimization-guided Neural Network (MOGNN) is proposed to optimize chemical processes. The model is trained with pre-selected process data, resulting from optimization of engineering models described by systems of algebraic equations. MOGNN aims to predict the optimal operating points for a range of input variables. The models were simulated in the Unisim-Design (R) process simulator for training data generation and optimized in Python using the Particle Swarm Optimization algorithm. The resulting models were applied to optimize two chemical engineering cases. The results showed that the computational cost of optimization corresponded to 0.83% and 2.12%, respectively, about the simulation cost for a given input dataset. Also, both processes revealed good alignment between the predicted profiles and the simulator data, while their respective objective function profiles yielded an average improvement of 9.61 % and 18.83% for the two examples.

关键词： Machine learning nonlinear programming Process simulation

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Optimization-Aided, Low-Energy Transfers via Vertical Instability Around Earth-Moon L1

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2021年第2期44卷 389-398页

作者： Oshima, Kenta Hiroshima Inst Technol Hiroshima 7315193 Japan

A study proposes the combined use of the vertical instability and optimization techniques to compute low-energy transfers changing the inclination and the out-of-plane amplitude substantially around L1in the Earth–moon CR3BP. The method consists of three stages of optimizations. The first stage computes initial guesses for manifold-guided transfers by maximizing the inclination while avoiding escapes from the vicinity of L1 against the strong horizontal instability. The CR3BP describes the motion of a massless particle P3, under the gravitational influences of two massive bodies, P1 and P2 of masses m1 and m2 (m1 > m2), respectively. The model assumes that P1 and P2 revolve in circular orbits around their barycenter.

关键词： Low Energy Trajectory Moon Earth nonlinear programming Near Rectilinear Halo Orbit Earth Centered Inertial Spacecraft Trajectories Mathematical Models Ecliptic Europa

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Optimization of periodic input waveforms for global entrainment of weakly forced limit-cycle oscillators

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nonlinear DYNAMICS 2021年第3期105卷 2247-2263页

作者： Kato, Yuzuru Zlotnik, Anatoly Li, Jr-Shin Nakao, Hiroya Tokyo Inst Technol Dept Syst & Control Engn Tokyo 1528552 Japan Los Alamos Natl Lab Appl Math & Plasma Phys Los Alamos NM 87545 USA Washington Univ Dept Elect & Syst Engn St Louis MO 63130 USA

We propose a general method for optimizing periodic input waveforms for global entrainment of weakly forced limit-cycle oscillators based on phase reduction and nonlinear programming. We derive averaged phase dynamics from the mathematical model of a limit-cycle oscillator driven by a weak periodic input and optimize the Fourier coefficients of the input waveform to maximize prescribed objective functions. In contrast to the optimization methods that rely on the calculus of variations, the proposed method can be applied to a wider class of optimization problems including global entrainment objectives. As an illustration, we consider two optimization problems, one for achieving fast global convergence of the oscillator to the entrained state and the other for realizing prescribed global phase distributions in a population of identical uncoupled noisy oscillators. We show that the proposed method can successfully yield optimal input waveforms to realize the desired states in both cases.

关键词： nonlinear oscillation Synchronization Phase reduction Optimization nonlinear programming

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Considerations and design goals for unbalanced optimal power flow benchmarks

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ELECTRIC POWER SYSTEMS RESEARCH 2024年 235卷

作者： Geth, Frederik Chapman, Archie C. Heidari, Rahmat Clark, Jordan GridQube Brisbane Australia Univ Queensland Brisbane Australia CSIRO Energy Business Unit Newcastle Australia

Distribution network constrained mathematical optimization is key technology to enable advanced distribution network management. In recent years, a growing amount of articles on the development of such models and algorithms have been published. Benchmarking of different approaches is crucial to establish performance trade-offs between accuracy, reliability and computational intensity. Today, practitioners tend to take ad -hoc approaches, building on power flow data sets but adding customer extensions to establish information such as voltage/current/power bounds and to parameterize pre -defined objective functions. To foster progress in this field, in this work we discuss (i) a number of design trade-offs and pitfalls related to benchmarking, (ii) develop a data model and mathematical specification for (up -to) four -wire optimal power flow, and (iii) develop some initial data sets. The data sets are provided through open -access initiatives under a creative commons license, and a reference implementation of the mathematical model is made available with a permissive license. For ease -of -use, and to maximize uptake in the community, we establish a tiered approach to the benchmark development with a multi -year plan.

关键词： Unbalanced optimal power flow Numerical optimization Benchmarking nonlinear programming

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Stability of Asymmetric Parallel Tunnels in Cohesive-Frictional Soils

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INTERNATIONAL JOURNAL OF GEOMECHANICS 2024年第1期24卷 04023256-04023256页

作者： Xiao, Yao Cheng, Zhouyang Hou, Zhenkun Zhang, Rui Guangdong Univ Technol Sch Civil & Transportat Engn Guangzhou 510006 Peoples R China Guangzhou Construct Engn Co Ltd Guangzhou 510030 Peoples R China Guangzhou Municipal Construct Grp Co Ltd Guangzhou 510030 Peoples R China Changsha Univ Coll Civil Engn Changsha 410022 Peoples R China

In this paper, finite-element limit analysis (FELA) in conjunction with nonlinear programming was developed and applied to evaluate the stability of asymmetric parallel circular tunnels in cohesive-frictional soils subjected to surcharge pressure. Based on the feasible arc interior point algorithm, a new imprecise step search algorithm was proposed to improve the speed of solving the optimization models. Meanwhile, an empirical judgment criterion was established for detecting the infeasibility of the problem. Based on the FELA method, the lower bound and upper bound for the dimensionless stability number were obtained, which account for the influence of material properties, including the overburden stress factor gamma D/c and the soil internal frictional angle phi, and geometric parameters, such as the normalized spacing ratio S/D, cover depth ratio H/D, and diameter ratio R/D of two tunnels. To obtain tight bounds for the failure load of the problem, an adaptive remeshing strategy was used in all of the numerical simulations. To facilitate practitioners' use, the calculated results were presented in the form of design tables and charts, and the failure modes for different parameters were compared and discussed. The stability numbers obtained from the present analysis are applicable to estimate the stability of asymmetric parallel circular tunnels in cohesive-frictional soils subjected to surcharge pressure. From the failure modes, engineers can identify critical sections of the asymmetric parallel tunnels where additional reinforcement or support may be required. This information can help to ensure that the asymmetric parallel tunnels remain stable during construction and in service, reducing the potential for failure and increasing the safety of the tunnels.

关键词： Asymmetric parallel tunnels Stability Finite-element limit analysis nonlinear programming Failure mechanism

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Hybrid-Field-Aware Two-Stage Beamforming Scheme for XL-MIMO Systems

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IEEE Internet of Things Journal 2025年

作者： Gao, Tianbao Song, Yunchao Liu, Chen Yin, Zhisheng Cheng, Nan Ge, Dan Nanjing University of Posts and Telecommunications college of Electronic and Optical Engineering Nanjing210023 China Xidian University State Key Laboratory of ISN and School of Telecommunications Engineering Xi’an710071 China

In this paper, we propose a hybrid-field-aware two-stage beamforming (HFA-TSB) scheme for extremely large-scale MIMO (XL-MIMO) systems. The HFA-TSB scheme can reduce the high pilot overhead associated with channel estimation by leveraging statistical channel state information (SCSI). Utilizing our derived ergodic spectral efficiency (SE), which relies solely on SCSI, we can eliminate the interference resulting from the non-orthogonality of near-field polar domain codewords. Specifically, the HFA-TSB scheme comprises two stages: pre-beamforming and precoding. In the pre-beamforming stage, we use SCSI to design the pre-beamforming matrix, focusing on eliminating interference among asymptotically orthogonal channels. This can establish an equivalent reduced-dimensional channel matrix, which can be estimated using less pilot overhead. Additionally, to address the interference caused by the non-orthogonality of near-field codewords, we derived an ergodic SE that relies solely on SCSI. Using this as an optimization objective, the pre-beamforming matrix design problem is formulated as a 0-1 integer nonlinear programming problem, which is challenging to solve. To address this, we propose a constraint-driven two-phase greedy beam selection algorithm for identifying effective beams. In the precoding stage, we design the precoder based on the estimated equivalent sparse channel to effectively mitigate any residual inter-user interference. Simulations validate the superior performance of our proposed HFA-TSB scheme in terms of net SE. © 2014 IEEE.

关键词： nonlinear programming

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