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    An Unbiased Grey Model Based on Euler Polynomial and Its Application in China's Primary Energy Production
    Shuliang Li, Ying Wang, Ruifeng Zheng, Wei Meng, Dajin Zeng
    The Journal of Grey System    2025, 37 (2): 1-15.  
    Abstract239)           
    A key property of grey prediction models is their unbiased nature, which focuses on eliminating discontinuity between differencing and differentiation during their construction. Meanwhile, an unbiased proof is required to ensure this property. In this paper, an unbiased EDGM(1,1) model incorporating Euler polynomials is constructed. Firstly, this model integrates Euler polynomials and a time disturbance parameter into the classical GM(1,1) model, enabling this EDGM(1,1) model to flexibly handle sequences with various data characteristics. Subsequently, the difference and its discrete forms are derived, and the latter is then solved using the least squares method and mathematical induction. Then the Particle Swarm Optimization (PSO) algorithm is implemented to improve the model's parameters. Secondly, the compatibility of the EDGM(1,1) model is demonstrated, and its unbiasedness towards three characteristic sequences is proven based on Cramer's rule. Finally, the performance of the EDGM(1,1) model is evaluated comprehensively against five competing models using three metrics: MAPE, RMSE, and R². The comparative analysis shows that the EDGM(1,1) model outshines other models in robustness and accuracy. Furthermore, the novel model is designed to forecast China's primary energy outputs, aiming to provide references for energy policies and decision-making. 
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    GreyShot: Zeroshot and Privacy-preserving Recommender System by GM(1,1) Model 
    Hao Wang
    The Journal of Grey System    2025, 37 (2): 16-22.  
    Abstract219)           
    Every recommendation engineer needs to face the cold start problem when building his system. During the past decades, most scientists adopted transfer learning and meta learning to solve the problem. Although notable exceptions such as ZeroMat etc. have been invented in recent years, cold-start problem remains a challenging problem for many researchers. In this paper, we build a zeroshot and privacypreserving recommender system algorithm GreyShot using GM(1,1) model by taking advantage of the Poisson-Pareto property of the online rating data. Our approach relies on no input data and is effective in generating both accurate and fair results. In conclusion, zeroshot problem of recommender systems could be effectively solved by grey system methods such as GM(1,1). 
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    Multivariate Fractional Grey Model for Port Throughput Prediction 
    Xinyu Wang, Xinquan Liu, Yingyi Huang, Che-Jung Chang, Jianhong Guo
    The Journal of Grey System    2025, 37 (2): 23-32.  
    Abstract355)           
    Accurate prediction of port throughput is critical for enhancing the precision of port construction decisions. However, identifying the factors influencing port throughput and constructing a robust predictive model remain significant challenges. To address this issue, this paper develops a modeling framework based on grey systems theory. First, grey relational analysis is employed to identify the relevant factors impacting changes in port throughput. These influencing factors are then utilized to construct a multivariate weighted fractional grey model for throughput prediction. To enhance the predictive capability of the grey model, this study establishes an error-based objective function to determine the model's fractional order, followed by corrections to the residual sequence using Long Short-Term Memory (LSTM) neural networks to improve prediction accuracy. To validate the effectiveness of the proposed method, empirical analysis is conducted using port throughput data from Guangxi Province, with comparisons made against four commonly used models. The experimental results demonstrate that the grey modeling framework proposed in this paper achieves high accuracy, with a 0.67% reduction in mean absolute percentage error (MAPE) outperforming alternative models. Furthermore, the model predicts a rapid growth trend in port throughput in Guangxi over the next three years, suggesting that expanding the utilization rate of existing port infrastructure and accelerating investments in capacity expansion are critical for meeting future demand. These results highlight the model's potential as a decision-support tool for strategic planning in the port and logistics sectors. 
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    A Novel Discrete Grey Model for China’s Carbon Emissions Forecasting 
    Xinyu Zhang, Jun Zhang, Siqi Dong
    The Journal of Grey System    2025, 37 (2): 33-49.  
    Abstract165)           
    Carbon emission projections are pivotal in addressing global climate change and advancing green, low-carbon development. Accurate forecasts of China's carbon emissions provide critical insights for policymakers to understand future emission trends and potential peak levels, thereby enabling the formulation of scientifically grounded and practical mitigation strategies. Discretization has proven to be an effective approach for enhancing the accuracy of grey prediction models. To further refine the performance of discrete grey prediction models, this study integrates integer-order polynomials with time fractional power terms to develop an optimized discrete grey prediction model, DGMPT(1,1,N, ), the particle swarm optimization (PSO) algorithm is utilized to optimize hyperparameters. To validate the model's superiority and predictive accuracy, this study applies it to the carbon emission data of Xinjiang, Shaanxi, and Gansu provinces in China. Empirical results demonstrate that, based on the mean absolute percentage error (MAPE) criterion, the proposed model achieves the lowest MAPE values in both the training and prediction datasets across all three case studies. Finally, the proposed model is employed to forecast China's carbon emissions over the next decade. The results indicate that under current conditions, China is unlikely to achieve its peak carbon emissions by 2030. This underscores the urgency of implementing effective and comprehensive policy measures to improve carbon emission systems and foster a sustainable emission environment. 
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    Research on Construction of a Novel Grey Clustering Model Based on Possibility Functions Considering Dynamic Contribution Degree and Its Application 
    Shuaishuai Geng, Zhaohan Hu, Jing Jia, Xiao Xu, Sandang Guo
    The Journal of Grey System    2025, 37 (2): 50-62.  
    Abstract216)           
    This paper evaluates the high-quality development of national central cities by proposing a novel grey clustering method for the comprehensive assessment of their developmental levels. This approach facilitates dynamic analysis of urban development status and contributes to the theoretical framework of grey evaluation methods, thereby providing a robust foundation for urban development decision-making. The proposed method addresses the limitations inherent in traditional grey possibility function clustering models, particularly their inadequacy for panel data analysis and their lack of dynamic measurement capabilities in evaluating indicator systems. The novel model incorporates time weighting by optimizing the weights of time point index attributes to derive time domain attribute weights. For panel data, observed values are integrated into a comprehensive evaluation framework, facilitating dimension reduction and the transformation of panel data into cross-sectional data. Subsequently, grey clustering analysis is applied to the cross-sectional data. The validity and feasibility of the proposed model in handling panel data are verified through an evaluation and analysis of the high-quality development of national central cities. 
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    Model Validation and Visualization Techniques of Grey Relational Analysis 
    Honghua Wu, Yafang Li, Xue Han, Aqin Hu
    The Journal of Grey System    2025, 37 (2): 63-76.  
    Abstract218)           
    To address issues in the validation and analysis methods of panel data-based grey relational analysis models (PD-GRA), this paper introduces various validation methods for the PD-GRA model, including Collision Testing Analysis (CTA), Stability Testing Analysis (STA), Permutation Testing Analysis (PTA), Rolling Window Time Analysis (RWTA), along with corresponding visualization techniques. These approaches are designed to analyze the robustness of grey relational analysis model (GRA). First, the concepts of strong and weak collisions for the GRA model are defined, along with their occurrences at different levels. Conclusions on strong and weak collisions are drawn for different GRA formulas. Second, STA, PTA, and RWTA are systematically presented to evaluate the stability of PD-GRA model from different perspectives. Meanwhile, visualizations for these three tests are also provided. Finally, a simulation analysis is conducted to examine the collision behavior of traditional GRA models. A case study is then used to apply STA, PTA, and RWTA to the PD-GRA model, accompanied by visualizations, offering deeper insights into the model's performance. 
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    Optimization of Petrochemical Energy Management System Based on Grey-Improved Parallel Moth Flame Optimization 
    Hongxia Chen, Bin Zhao
    The Journal of Grey System    2025, 37 (2): 77-86.  
    Abstract118)           
    In order to improve the profit, reduce the shutdown loss and enhance the environment benefit, an optimization model of petrochemical energy manage system is established based on improved parallel moth flame optimization algorithm (IPMFOA). Firstly, the petrochemical energy management system optimization model is constructed, and the object function and constraint condition are confirmed. Secondly, an Grey-IPMFOA is established. Finally, an energy management system of refinery in a petrochemical company is selected as research object to carry out optimization analysis based on proposed Grey-IPMFOA and other three optimization algorithms, results show that proposed optimization can get best optimal effect and highest optimal efficiency. In addition, proposed Grey-IPMFOA has better convergence performance and computation complexity. The energy management system after optimization has high profit, low shutdown loss and high environment benefit. 
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    Grey Double-layer Particle Swarm Optimization Algorithm of Testability Allocation for Complex Systems in the Context of Grey Information 
    Youpeng Liu, Zhigeng Fang, Shiyun Zhang, Cuiping Niu, Jingru Zhang
    The Journal of Grey System    2025, 37 (2): 87-99.  
    Abstract127)           
    The conventional series system and parallel system are no longer able to adequately address the current system condition due to the rapid advancement of science. If faults are not identified and isolated, any system failure can lead to the inability to perform a single task or even multiple tasks. In order to promptly identify and isolate faults, the systems must have high testability. However, problems like omitting structural elements in testability influencing factors and ambiguous testability-related data make standard approaches useless when building and resolving testability allocation models. The grey optimization approach will lose a lot of grey information if a planning model is employed for solution, which will lead to large inaccuracies. Therefore, this paper proposes a testability allocation model for complex systems in the setting of grey information, and proposes the grey double-layer particle swarm optimization algorithm to solve the model. First, the particular factor that influence the testability allocation process is identified. Second, this paper proposes the TOPSIS method based on the improvement of grey entropy weight and determines the weights of the subsystems. Then, this paper proposes the grey nonlinear planning testability allocation model, and proposes the grey double-layer particle swarm optimization algorithm to solve the model. Finally, the viability and efficacy of the model are demonstrated by strength testing and comparison with other algorithms. 
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    Risk Assessment of Human Resource Crises in Offshore Engineering Design Enterprises Using a Grey Evaluation Model #br#
    Tao Li, Luping Zhang, Haoyu Zhang
    The Journal of Grey System    2025, 37 (2): 100-114.  
    Abstract122)           
    This study investigates human resource crisis management in Offshore Engineering Design (OED) enterprises, focusing on the specific challenges faced by Chinese firms. The research develops a comprehensive early warning indicator system, integrating 15 qualitative and 21 quantitative indicators across five key dimensions. Given the limitations posed by insufficient data and inherent uncertainties in the evaluation process, this study also presented a grey evaluation method to construct a risk assessment model for OED human resource crises. A case study of AOED reveals critical issues, including inefficiencies in performance assessment and high staff turnover, underscoring the need for enhanced management strategies. The findings contribute to improving OED human resource management and provide a foundation for future research on predictive models in OED contexts.
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    Complex Decision Making in Counties Socio-Economic and Security Contexts through Grey Clustering 
    Camelia Delcea, Constantin Marius Profiroiu, Alina Georgiana Profiroiu, Bianca Raluca Cibu, Ionuț Nica, Liviu-Adrian Cotfas
    The Journal of Grey System    2025, 37 (2): 115-135.  
    Abstract125)           
    This paper examines the impact of varying the significance of socio-economic and security indicators on the satisfaction levels of citizens across different counties in Romania and Republic of Moldova. Using grey clustering analysis, a powerful tool offered by the grey systems theory, the counties are grouped into three clusters based on citizen satisfaction. Five different scenarios are explored, each assigning distinct weights to socio-economic and security indexes to evaluate their influence on the clustering outcomes. The findings indicate that increasing the emphasis on socio-economic factors leads to more counties experiencing higher levels of citizen satisfaction, particularly in Romania, where socio-economic stability is more robust. On the other hand, placing greater importance on security factors exposes governance-related challenges, as a clear division between the counties in Romania and Republic of Moldova can be observed. While when considering the security indexes, more counties are pushed in the higher levels of satisfaction clusters for the counties in Republic of Moldova, an opposite trend can be encountered for the counties in Romania. 
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    Prediction of China’s Fossil Energy Consumption Using GRNN-Based Grey Multivariable Model
    Jiayi Liu, Jun Zhang
    The Journal of Grey System    2025, 37 (3): 1-10.  
    Abstract194)           
    In view of the dominant position of fossil energy in global energy consumption and the environmental problems caused by excessive use of fossil energy, accurate prediction of fossil energy consumption is of great significance for formulating scientific energy policies and optimizing energy structure. Traditional forecasting methods have limitations when dealing with small samples, nonlinear and multi-factor problems, while grey system theory and neural network model are good at dealing with uncertainty and nonlinear mapping respectively. Therefore, this study hybridizes the generalized regression neural network (GRNN) model on the basis of the dynamic nonlinear grey delay multivariable Logistic model, i.e. NGDM(1, N), and constructs grey NGDM(1, N)-GRNN hybrid model to further optimize the prediction results. Particle swarm optimization (PSO) algorithm was used to optimize grey model parameters, and the optimal smoothing factor of GRNN model was found through cross-validation, which improved the prediction accuracy of the model. The empirical results show that compared with the single NGDM(1, N) model and GRNN model, the proposed hybrid model has smaller errors in the short-term prediction of fossil energy consumption, and has better forecasting effect.
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    Forecasting the Amount of Urban Domestic Waste Clearance in China With an Optimized Grey Convolution Model
    Sandang Guo, Xu Han, Jing Jia, Shuaishuai Geng
    The Journal of Grey System    2025, 37 (3): 11-23.  
    Abstract145)           
    Accurate forecasting of urban domestic waste clearance in China is essential for advancing the sustainable development of urbanization. To this end, this paper proposes a novel nonlinear grey convolution model that incorporates background value optimization. Firstly, this model introduces power exponents to enhance its ability to capture the nonlinear characteristics of the system. And then, it also analyzes the sources of errors in the background value calculation of traditional models and effectively addresses this issue by incorporating dynamic interpolation coefficients. Besides, the optimal hyperparameters of the model are determined using particle swarm optimization (PSO). In two distinct case studies, the proposed model was rigorously compared with five forecasting models across three distinct domains, consistently demonstrating its superior performance.
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    The Generalized Grey Bass Model and Its Applications
    Zhaoya Zhang, Naiming Xie, Yingjie Yang, Xiaolei Wang
    The Journal of Grey System    2025, 37 (3): 24-36.  
    Abstract122)           
    The grey Bass model serves as a valuable tool in forecasting time series portraying inverted U-shaped characteristics. However, the existing grey Bass model still has some issues in inaccuracies for the Cusum operator and the rationale behind selecting the initial value for parameter estimation. To improve the accuracy and applicability of the grey Bass model, the generalized grey Bass model is developed, incorporating the physics-preserving Cusum operator with second-order accuracy. Initially, the relationship between the generalized grey Bass and the traditional grey Bass models is elucidated via parameter transformation. Subsequently, opting for the first observation as the initial value is proven to be not only accurate but also a highly efficient strategy. Additionally, extensive simulations are conducted to compare both models in terms of robustness against discretization errors, measurement noise, and sample size. Finally, the generalized grey Bass model is applied to two real-world cases and evaluated against competitive models regarding accuracy and stability. Results demonstrate that the generalized grey Bass model exhibits superior precision and exceptional modeling performance.

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    A Variable-order Nonlinear Discrete Grey Multivariate Model with New Information Priority Accumulation and Its Applications
    Yang Cao, Min Sun, Qinqin Shen, Xiaofei Liu
    The Journal of Grey System    2025, 37 (3): 37-49.  
    Abstract130)           
    In order to overcome some defects of the existing grey multivariate convolution model with new information priority accumulation (GMCN(1,N)), such as the neglect of variable heterogeneity analysis, the weak capability in nonlinear feature extraction, and the mismatch between model parameter estimation and time response function, based on the ideas of variable-order accumulation and discrete grey models and by introducing an additional nonlinear correction term, a variable-order nonlinear discrete grey multivariate model with new information priority accumulation is proposed. Basic properties of the new model are analyzed. Solution structure as well as model parameters are derived. In addition, the quantum particle swarm optimization algorithm is adopted to seek for the optimal accumulation orders. Finally, the proposed model is applied to two practical cases for multidimensional evaluation. The results indicate that the new model outperforms the classic GM(1,N) model, the existing GMCN(1,N) model, and several recently proposed grey multivariate models in terms of both fitting and prediction accuracy, demonstrating better stability and generalization capability.
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    Grey Forecasting Modeling for Deteriorating Inventory with Price Dependent Demand
    Xiaolei Wang, Naiming Xie
    The Journal of Grey System    2025, 37 (3): 50-60.  
    Abstract88)           
    To tackle the challenges of inventory models in practical applications, this paper introduces a grey forecasting modeling approach to uncover the inventory differential equation and subsequently develops an inventory optimization model. Firstly, for deteriorating products with price-dependent demand, this article formulates a differential equation to describe inventory levels by analyzing the inventory system and develops an optimization model aimed at maximizing inventory profits. Based on the idea of grey forecasting modeling, this article discusses the problem description of identifying the inventory differential equation. Then, by using the cumulative generation operator, the parameter estimation of the inventory differential equation is transformed into a regression problem. A numerical example is presented to illustrate the steps of grey forecasting modeling. The simulation results validate the feasibility of the grey forecasting modeling in the simulation case.
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    A Novel Grey MCDM Model Assessing Macroeconomic Performance of G7 Countries
    Alptekin Ulutaş, Ayse Topal, Darjan Karabasevic, Edmundas Kazimeras Zavadskas, Muzaffer Demirbaş, Salim Üre
    The Journal of Grey System    2025, 37 (3): 61-72.  
    Abstract208)           
    Macroeconomic indicators offer critical insights into the economic performance of nations. The potential variability of these factors necessitates formulating policies and implementing actions to counteract any adverse situations that may arise. This research aims to evaluate the macroeconomic performances of the seven developed nations, known as the G7 nations. The research identified imports of goods and services, exports of goods and services, gross fixed capital formation, gross domestic savings, unemployment, population, current account balance, inflation, consumer prices gross domestic product as criteria for performance assessment. An integrated framework integrating the LOPCOW-G and RAWEC-G methodologies is presented to assess the macroeconomic performance of G7 nations within the study's framework. The weight values derived from the LOPCOW-G technique indicate that the current account balance is the most significant factor influencing macroeconomic success. The RAWEC-G technique findings indicate that Japan had the highest economic performance, while the USA demonstrated the lowest economic performance.
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    Analysis of Grey Correlation Between Professional Layout and Industrial Structure in Xinjiang Higher Vocational Colleges
    Ping Wang, Jiaming Liang, Jihong Sun
    The Journal of Grey System    2025, 37 (3): 73-82.  
    Abstract93)           
    The rapid development of the economy in Xinjiang has brought about an increased emphasis on the coordination between the major layout and the industrial structure of Xinjiang higher vocational colleges. This study investigates the correlation between the major layouts of these institutions and the regional industrial structure through the use of an integrated grey system framework. The employment of grey correlation modeling (ρ=0.5) and a particle swarm-optimized fractional grey prediction model (FGM(1,1) with r=0.75) has led to the following three key findings: Firstly, the overall major layout of higher vocational colleges in Xinjiang is largely consistent with the current industrial structure demand. Secondly, it will be necessary to strengthen the construction of majors related to emerging industries and modern service industries to adapt to changes in the industrial structure. Thirdly, the findings prove that the fractional-order grey prediction model is an advanced scientific approach to adapt the major layout to regional industries, which provides a better tool in serving local economic and social development. These findings validate the efficacy of fractional grey models in the realm of vocational education planning, offering a replicable framework for the management of industrial transition in developing regions.
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    EEG-GRA Cross-Sequence Feature Extraction Method for Operator Cognitive Fatigue
    Lidan Chen, Xi Liu, Ying Lin
    The Journal of Grey System    2025, 37 (3): 83-95.  
    Abstract126)           
    This paper introduces an advanced EEG-GRA cross-sequence feature extraction method for operator cognitive fatigue detection in industrial settings. Our research addresses key limitations in conventional approaches through three technical innovations: (1) an intelligent adaptive time-varying weight function system that continuously calibrates to operator cognitive states, (2) an advanced multi-scale analysis framework incorporating state-of-the-art wavelet decomposition, and (3) a sophisticated cross-sequence feature fusion mechanism that leverages spatial correlations across EEG channels. Comprehensive performance evaluation reveals significant quantifiable improvements: the system achieves a 45% reduction in processing time (from 100ms to 55ms), enabling genuine real-time monitoring capabilities; detection accuracy shows a remarkable increase of 17.5 percentage points (from 76% to 93.5%); and signal quality demonstrates a substantial improvement of 5.3dB (from 15dB to 20.3dB). These advances are achieved while simultaneously reducing computational demands, with algorithmic optimization decreasing complexity from O(n²) to O(n log n) and memory requirements reduced by 38%. Field implementation in a nuclear power plant control room involving 30 operators under rigorous operational conditions validated the system's exceptional reliability, maintaining 99.99% uptime during 12-hour continuous monitoring shifts. Statistical analysis confirms the significance of these improvements (p < 0.01), establishing a new benchmark for industrial safety systems across high-risk sectors.
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    Application of Grey Programming in the Configuration of Commercial Gymnasium Equipment
    Shanqing Yan, Xianyun Chu
    The Journal of Grey System    2025, 37 (3): 96-105.  
    Abstract96)           
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    Enhancing False Information Detection in Social Networks Using Grey Relational Clustering
    Yufeng Huang, Lianfeng Lai, Tingcheng Chang
    The Journal of Grey System    2025, 37 (3): 106-119.  
    Abstract91)           
    In the digital age, the rapid dissemination of false information on social networks presents certain societal challenges. Traditional detection methods have some limitations in handling data uncertainty and incompleteness common in social media environments. Therefore, this study proposes a grey relational clustering model, tentatively integrating content features, user behaviors, and propagation network features to better address data uncertainty and incompleteness. Preliminary comparative experiments with conventional machine learning and deep learning approaches indicate that our model maintains accuracy above 85% even when 30% of data is missing, and achieves an accuracy of 92% and an F1-score of 0.92 on complete datasets. Additionally, the model demonstrates certain advantages in computational efficiency, being approximately 2.5 times faster than traditional machine learning models and about 9 times faster than BERT. This research hopes to contribute modestly to real-time false information detection by providing a relatively efficient and somewhat adaptive analytical tool for social media environments.
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