Construction Of Theoretical Model Research Articles

COSMA-RF: New intelligent model based on chaos optimized slime mould algorithm and random forest for estimating the peak cutting force of conical picks

Since conical pick cutting is a complex process of multi-factor coupling effects, theoretical model construction for cutting force prediction is a quite difficult task. In this paper, various novel intelligent models based on chaos-optimized slime mould algorithm (COSMA) and random forest (RF) are proposed for this task. In the proposed COSMA-RF methods, the chaos algorithms with the ergodicity and randomness are introduced to chaotically determine the initial position to form a COSMA, and the SMA and COSMA are used to tune the hyperparameters of RF and mean square error are assigned as a fitness function. Consequently, 205 data samples having seven variables (tensile strength of the rock σt, compressive strength of the rock σc, cone angle θ, cutting depth d, attack angle γ, rake angle α and back-clearance angle β) and one output parameter peak cutting force (PCF) are collected from previous literature. Additionally, the performance of optimal COSMA-RF models is comprehensively compared with the existing theoretical formulae and four common machine algorithms, namely RF, extreme gradient boosting, extreme learning machine and back propagation neural network. The results indicate that Logistic map optimized SMA (LSMA), Sine map optimized SMA (SINSMA) and Sinusoidal map optimized SMA (SSMA) have better convergence ability and accuracy compared with original SMA. LSMA-RF, SINSMA-RF and SSMA-RF models yield better PCF prediction performance compared with theoretical formulae and common machine algorithms. Furthermore, sensitive analysis shows σt, σc, d and β are significantly sensitive to PCF.

Optimization of Spatial Pattern of Land Use: Progress, Frontiers, and Prospects.

Due to high-intensity human disturbance and rapid climate change, optimizing the spatial pattern of land use has become a pivotal path to restoring ecosystem functions and realizing the sustainable development of human–land relationships. This review uses the literature analysis method combined with CiteSpace to determine current research progress and frontiers, challenges, and directions for further improvement in this field. The main conclusions include the following: (a) research on the optimization of spatial pattern of land use has transformed from pattern description orientation to sustainable development orientation to ecological restoration orientation. Its research paradigm has changed from pattern to function to well-being; (b) the research frontier mainly includes spatial pattern of land use that takes into account the unity of spatial structure and functional attributes, the ecological mechanism and feedback effect of change in spatial pattern of land, the theoretical framework and model construction of land use simulation and prediction based on multiple disciplines and fields, and the adaptive management of sustainable land use in the context of climate change; (c) based on current research challenges, we integrate the research on landscape ecology and ecosystem service flows to develop an “element sets–network structure–system functions–human well-being” conceptual model. We also propose the strengthening of future research on theoretical innovation, spatiotemporal mechanism selection, causal emergence mechanism, the transformation threshold, and uncertainty. We provide innovative ideas for achieving sustainable management of land systems and territorial spatial planning with the aim of improving the adaptability of land use spatial optimization. This is expected to strengthen the ability of land systems to cope with ecological security and climate risks.

Modeling of Surface Nuclear Magnetic Resonance Based on Prepolarization and Its Application in Urban Shallow Measurements

Surface nuclear magnetic resonance (SNMR) technology is a geophysical method to directly measure the water content and saturated porosity of aquifers by exciting the nuclear magnetic resonance (NMR) phenomenon of hydrogen nuclei in groundwater. With the natural Earth magnetic field B0 as the background detection field, the SNMR signals, which usually exist only within a range of tens of nanovolts, are very likely to be submerged in widespread environmental noise. The prepolarization (PP) method with artificial application of an active field to enhance NMR signals has been gradually applied to the SNMR field, and this method is expected to overcome existing problems and to gain further development in more high-noise detection environments, e.g., urban engineering detection. However, when PP is introduced to SNMR, difficulties in data interpretation focus on the theoretical formula derivation and model construction. In this paper, we studied the state of the detected target under a PP field. Based on currently available measurement processes, we established the corresponding PP-SNMR forward equations and modeling for groundwater. It was proven by simulation and actual measurements that the research in this study can interpret actual field detection data. In addition, compared with the conventional PP-SNMR theory, the proposed improved method can effectively avoid detected aquifer misestimation. The results gained in this study compensate for the shortcomings of the current PP-SNMR theory, which is of significance to the development and application of high-power PP-SNMR technology.

Analysis of Theoretical and Experimental Research on Bubble Parameters and Gas-liquid Interaction in Bubble Flow

Bubble flow is a phenomenon in which gas flows with liquid in the form of bubbles, which widely exists in production and life. As an important part of fluid mechanics, bubble flow also has a certain impact on the actual production process. This work briefly summarizes the development of research on bubble flow in recent years. Firstly, a brief introduction to the development process and current situation of bubble flow in chronological order is presented, and the main difficulties related to the research and development of bubble flow are also pointed out, including the complicated gas-liquid distribution pattern and the exchange of materials and energy between gas and liquid phases, which slow down scholars’ research progress. Then, several theoretical models for bubble flow research are introduced. These models take bubble parameters into account, including the ultimate velocity of bubble rising, the transfer of energy and matter in the coalescence, and rupture of the bubble, the phase distribution of the bubble in the tube, and the interaction between the bubble and the liquid (the shear stress produced by bubbles affecting the turbulence field). This work briefly explains the ideas of each model and the results obtained, compares and analyzes their advantages, disadvantages and limitations, and predicts the theoretical and technical means required for subsequent theoretical model construction. Finally, part of the experimental research is summarized, along with the process and technical means of each experiment as well as the relationship between the experimental results and the theoretical research. It is hoped that this work could help to have a preliminary understanding of the research process and research methods of bubble flow, and provide some perspectives for incorporating bubble flow hydrodynamic theory into industrial applications and real life.

Impact of Energy Structure Adjustment and Environmental Regulation on Air Pollution in China: Simulation and Measurement Research by the Dynamic General Equilibrium Model

In recent years, the average concentration of PM2.5 in China's air pollution has generally declined, but literature discussing reasons for the decline are scarce. This study provides an explanation of the reasons for the decline in China's air pollution through theoretical model construction and simulation. Firstly, a DGE (Dynamic General Equilibrium) model, including time and space dimensions, is used to describe the mechanism for energy structure adjustment and environmental regulation affecting air pollution in China. Secondly, the parameters of the theoretical model are adjusted for simulation. The simulation results show that the government environmental control has positive policy effect, both in reducing air pollution and in promoting economic growth, while energy structure adjustment only works in curbing air pollution. Further simulations found that the effectiveness of government environmental control depends on whether there are regional differences in policy implementation and the choice of policy paths. Thirdly, panel data from 286 cities at prefecture level and above in China from 2010 to 2018 verified the simulation. The empirical results verified the availability of government environmental control and energy structural adjustment in improving air quality. From the analysis of heterogeneity, the government environmental control showed better air pollution control effect in big cities, and the policy effect of government environmental control was gradually improving over time. The following policy implications are proposed: research on alternative energy sources, adjustment of energy structure, and the coordinated development of government environmental control in various regions are the main strategies for improving air quality. Adopting the "fast first and then slow" governance policy, designing the "north first and then south," and "heavy first and lighter" air pollution control measures can achieve better control effects.

Binary tree pricing method of farmland management right mortgage based on machine learning and complex network algorithm

At present, the mortgage loan of farmland contractual management right is in the pilot and exploration stage. In this overall environment, how to formulate an appropriate pricing model according to the particularity of farmland property right and the actual situation is the theoretical support to be solved. On the basis of theoretical analysis, model construction and analysis of existing problems, this paper establishes a binary tree pricing method of farmland management right mortgage based on machine learning and complex network algorithm. This paper analyzes the basic theory of rural land management right mortgage pricing and constructs the pricing model. Based on the Markov decision process model of dynamic pricing problem, this paper proposes the solution algorithm and proposes the dynamic pricing solution for this paper from two aspects of value function and strategy gradient reinforcement learning algorithm. This paper analyzes the basic principle of A3C algorithm and expounds the algorithm design and neural network architecture for the specific dynamic pricing problem in this paper. The dynamic pricing method of rural land mortgage based on deep reinforcement learning designed in this paper can well predict the real price of rural land management right mortgage pricing and effectively optimize the mortgage loan environment of rural contracted land management right, which is the innovation of financial system in the current new rural construction.

Research on Multi-Target Network Security Assessment with Attack Graph Expert System Model

With the rapid development of the Internet, network attacks often occur, and network security is widely concerned. Searching for practical security risk assessment methods is a research hotspot in the field of network security. Network attack graph model is an active detection technology for the attack path. From the perspective of the attacker, it simulated the whole network attack scenario and then presented the dependency among the vulnerabilities in the target network in the way of directed graph. It is an effective tool for analyzing network vulnerability. This paper describes in detail the common methods and tools of network security assessment and analyzes the construction of theoretical model of attack graph, the optimization technology of attack graph, and the research status of qualitative and quantitative analysis technology of attack graph in network security assessment. The attack graph generated in the face of large-scale network is too complex to find the key vulnerability nodes accurately and quickly. Optimizing the attack graph and solving the key attack set can help the security manager better understand the security state of the nodes in the network system, so as to strengthen the security defense ability and guarantee the security of the network system. For all kinds of loop phenomena of directed attribute attack graph, the general method of eliminating loop is given to get an acyclic attack graph. On the basis of acyclic attack graph, an optimization algorithm based on path complexity is proposed, which takes atomic attack distance and atomic weight into consideration, and on the basis of simplified attack graph, minimum-cost security reinforcement is carried out for the network environment. Based on the ant colony algorithm, the adaptive updating principle of changing pheromone and the local searching strategy of the adaptive genetic algorithm are proposed to improve the ant colony algorithm. The experimental results show that compared with the ant colony algorithm, the improved ant colony algorithm can speed up the process of solving the optimal solution. When the number of attack paths is large, the advantages of the improved ant colony algorithm in solving accuracy and late search speed are more obvious, and it is more suitable for large-scale networks.

Hanger forces optimization of ground test device on deployable structure

When using suspension method to simulate the microgravity environment, part of the hanger forces are used to offset the influence of gravitational field on the deployable structure, while the other part produces additional forces that affect the driving forces and precision of the deployable structure. In order to reduce the adverse effect of hanger forces, and avoid the construction of complex finite element theoretical model, an optimization method based on adaptive genetic algorithm with MATLAB and Nastran co-simulation is proposed. Then, the hanger forces are optimized, and the deployable structure deformation has been reduced 49%. It suggests that the adverse effect of hanger forces has been effectively reduced and the proposed optimization method works well.

CONCEPTUAL MODEL FOR SME DIGITAL TRANSFORMATION DURING THE COVID-19 PANDEMIC TIME IN INDONESIA: R-DIGITAL TRANSFORMATION MODEL

Digital transformation is one that has been accelerated in response to the COVID-19 pandemic that has hit the world since the end of 2019. As a sector that has proven reliable in facing the SME crisis, it is encouraged to accelerate its digital transformation process due to the distance limitation policy imposed during the pandemic. This article aims to assess the importance of understanding the right digital transformation model for each SME, especially in taking advantage of the accelerated momentum due to the social restriction policies imposed during the COVID-19 pandemic, because choosing the right model will provide a better probability of successful transformation. This research is qualitative research through content analysis to produce a theoretical model construction of the digital transformation model for SMEs in Indonesia which we call the reasonable digital transformation model for SME (R-DT for SME). The conclusion obtained is that based on the mapping of the digital transformation of SMEs in Indonesia on the R-DT model, it can be concluded that: (1) The main trigger for DT UKM is the external driver, not many internal drivers have been found, especially during the COVID-19 pandemic. what is done is still reactive in nature and tends to only follow the steps of the transformation of other actors so as not to create a uniqueness of the said SMEs which will result in the loss of opportunities to have a competitive advantage over competitors; (2) In general, the implementers of DT UKM have set a strategic imperative for their decision to carry out digital transformation, but have not set a measurable milestones so that the digital transformation carried out cannot be measured the level of success; (3) DT which is done in general is to change some of the company's operations to digital, this shows the low digital maturity of SMEs in Indonesia today.

Numerical simulation on dynamic damage evolution of high pure copper with different grain sizes

High-purity (HP) copper targets with grain sizes of 50, 130 and 200 μm are constructed by using the Voronoi method. Damage nucleation points are randomly prefabricated at the grain boundaries. A two-dimensional axisymmetric finite element model is established to simulate the spallation experiment of HP copper target. The effects of grain size and loading stress on the macro- mechanical response and meso-damage evolution of HP copper spallation are studied and compared with the relevant experimental results. Based on the analysis of free surface velocity profiles, the effects of grain size on the location of pull back velocity rebound point, velocity rebound slope and velocity rebound amplitude are revealed. It is demonstrated that the spalling strength corresponds to the peak value of tensile stress in the damage zone, which essentially represents the critical stress of micro damage nucleation or early growth. Based on the characteristic analysis of damage evolution nephogram, the evolution process of localized plastic strain field around the micro-voids in the growth and coalescence process is reproduced, and the strong dependence of micro-void coalescence behavior on grain size is clarified. The loading stress amplitude has little effect on the location of pull back velocity rebound point, but has a significant effect on the growth and coalescence behavior of micro-voids. The slope and amplitude of pull back velocity rebound increase with loading stress increasing, which is consistent with the relevant experimental result. With the increase of the loading stress, the micro-voids grow from independent growth to coalescence, thus forming spalling surface. The physical process of damage evolution determines the wave oscillation characteristics after the pull-back rebound point. The numerical simulation results reproduce the physical process of damage evolution and its influence on the macroscopic mechanical response, which is of great significance for further understanding spall damage evolution mechanism and theoretical model construction.

Proposal of Spherical Speed Reducer that Constraints Rotation Axis of Intermediate Balls and Construction of Theoretical Rotation Transmission Model for the Reducer

Proposal of Spherical Speed Reducer that Constraints Rotation Axis of Intermediate Balls and Construction of Theoretical Rotation Transmission Model for the Reducer

Research on Evaluation Method of Ecological Environment Quality Based on the Improvement of Human Settlement Environment

Against the background that ecological environment quality has become a hot research topic in recent years, ecological environment quality assessment has emerged as an emerging discipline. By adopting scientific methods, it objectively and quantitatively reveals the real situation of ecological environment quality, and is committed to providing support basis for environmental protection and comprehensive prevention and control. Therefore, how to develop a reasonable eco-environmental quality assessment system has become the focus of attention. Based on this, this paper summarizes the research results in this field at home and abroad, and discusses and illustrates the main existing evaluation methods and evaluation models through horizontal and vertical analysis. The development status of ecological environment quality evaluation research field and the application characteristics of different evaluation methods are analyzed, some problems in theoretical innovation, model construction and application of conclusions are discussed, and the development trend of ecological environment quality evaluation research is proposed based on this.

Theoretical Foundation and Model Construction of Comprehensive Evaluation of Distribution Network

As my country's economy has shifted from a stage of rapid growth to a stage of high-quality development. The scale of the distribution network is gradually increasing, and the manpower, material and financial resources involved are increasing day by day. Therefore, scientific comprehensive investment evaluation and decision-making for the distribution network is of great significance to the sustainable development of the distribution network. Based on hierarchical analysis method and entropy weight method, this paper proposes an evaluation model of analytic hierarchy process based on entropy weight. Score the indicators of 142 substations in a city, and calculate the comprehensive score of each substation. According to the evaluation results, relevant suggestions are given for the next stage of investment in different power supply stations in a certain city. On this basis, the analytic hierarchy process based on entropy weight is improved. Combining the variable weight theory to optimize the weight calculated by the model, and then obtain a more reasonable comprehensive score of the substation.

Linking Corporate Social Responsibility (CSR) and Organizational Performance: the moderating effect of corporate reputation

The study empirically investigates the relationship between corporate social responsibility (CSR) and organizational performance from the perspective of European multinational firms. Further, the study examines the effectiveness of corporate reputation as a moderator on CSR-organizational performance linkages. Final data comprised 340 responses collected from senior executives/managers working in European multinational firms. A two-stage approach was used to analyze the association: stage 1 involved theoretical model construction using the strategic paradigm of literature; in stage 2, hierarchical regression analysis was performed to examine the relevant relationships. Results have shown that CSR, when exercised towards external stakeholders, influences organizational performance. Moreover, this influence has been found to vary between well-established, reputable firms and business firms with weaker reputations.

Optical properties of electrochemically etched N-type silicon wafers for solar cell applications

Abstract The presented experiments and studies are intended for photovoltaic applications of crystalline silicon. This work deals with chemical treatment of the surface of n-type silicon wafers with different resistivity to reduce their reflectivity. Chemical surface treatment of silicon is an alternative method to using the antireflection layer. Optical losses caused by the reflection of light from the surface of the solar cells significantly reduce their efficiency. The investigated samples were prepared by the electrochemical etching method in the solution based on hydrofluoric acid and ethanol. The analysis of the prepared samples is divided into two parts, namely experimental measurements, and theoretical modeling. Experimental measurements are performed using UV-VIS spectroscopy, spectroscopic ellipsometry and SEM microscopy. Theoretical modeling is based on the construction and optimization of theoretical model of optical response (reflectivity and ellipsometric parameters) to determine the effective refractive index and thickness of formed structure. Effective refractive index of studied samples in theoretical model of optical response is based on Looyenga effective medium approximation and Tauc-Lorentz dispersion model.

International capital flows in club of convergence

PurposeThe paper analyzes the pattern of international capital flows, accounting for the convergence on economic growth.Design/methodology/approachThe paper employs an empirical analysis combined with a theoretical model. The evidence is based on a cross-section regression over a sample of 172 economies. And the model is an open multi-country overlapping generation (OLG) economy.FindingsThe empirical evidence records that the pattern of international capital flows in the club of convergence can diverge from the pattern in the club of unconvergence. A higher productivity growth rate is associated with more net capital inflows in the club of convergence but less net capital inflows in the club of unconvergence. The theory shows that proximity to world technology frontier can explain the divergence of capital flows.Research limitations/implicationsThe result can account for controversies between theories on the cross-border capital flows: allocation puzzle, up-hill capital flows and neoclassical growth model.Originality/valueThe paper combines both the empirical analysis with the theoretical model construction to account for the role of convergence of economic growth on determining the pattern of international capital flows.

Construction of Theoretical Model for Sustainable Development in Future Mathematical Teachers of Higher Education

In this paper, the authors have identified the main features of constructing a theoretical model of the content part of the future mathematics teachers' training system in a pedagogical institution of higher education in Ukraine in the context of the implementation of the education model for sustainable development. In order to build such a model, the authors have organized a study in the form of an expert survey of specialists in the field of education, specialists in fundamental mathematical disciplines and in the methodic of teaching mathematics, master students, as well as mathematics teachers - participants in retraining courses. The authors have determined the discipline (methodic of teaching mathematics) which became the basis for the model of the content of the future mathematics teachers' training system in the context of the implementation of the education model for sustainable development. The above course in the content such choice has been confirmed by the integration properties and capabilities of the discipline, the potential of its substantive and methodological components for the generalization and systematization of mathematical, pedagogical, natural-scientific and humanitarian knowledge and skills, as well as for the formation of systemic thinking. When studying the issue including a special course in the content part of teacher staff training program, aimed directly at creating an understanding of a human's role and one's dependence on nature, at creating a peaceful and open society, where everyone would have equal rights and opportunities, the authors have distinguished disagreements in experts' opinions.

Theoretical model construction and structure optimization of electromagnetic flow transducer based on neural network

Theoretical model construction and structure optimization of electromagnetic flow transducer based on neural network

Construction of theoretical model of traditional Chinese medicine intelligent manufacturing

In the process of transforming and upgrading of traditional Chinese medicine( TCM) intelligent manufacturing,the TCM enterprises lack systematic and in-depth research on intelligent manufacturing of TCM,leading to insufficient understanding of relevant concepts,development direction,development content and other aspects,to some extent,causing fuzzy and chaotic phenomena. The theoretical model,as a higher expression level of scientific thinking,has the function of interpretation and prediction,and can provide theoretical basis as well as guide for scientific research. Therefore,this article aims to construct a theoretical model of TCM intelligent manufacturing based on the concept of flexible production and intelligent equipment for some unhealthy phenomena in the development process of TCM intelligent manufacturing. In the TCM intelligent manufacturing system,with theory model as the core,the new-generation information technology was integrated with the TCM manufacturing technology to realize the integration of informationization and industrilization as well as the landing of theoretical model. Then,a 3 D simulation model was established to provide a visual environment for intelligent manufacturing of TCM and simulate the virtual reality throughout the TCM intelligent manufacturing process. The new theoretical model in this paper,to a certain extent,can play a guiding role in the development of TCM intelligent manufacturing,and can also provide reference for the realization of TCM intelligent manufacturing.

Theoretical Model Construction and Empirical Verification of Protective Action Decision Making during Disaster: Structural Equation Modeling of the Social Survey on Landslide Disasters in Oita Prefecture

Theoretical Model Construction and Empirical Verification of Protective Action Decision Making during Disaster: Structural Equation Modeling of the Social Survey on Landslide Disasters in Oita Prefecture