Search results
1 – 10 of over 33000Jinjing Li, Cathal O’Donoghue, Jason Loughrey and Ann Harding
The purpose of this paper is to investigate the state of the art in static and dynamic games (or inter‐firm relationships). This research area has changed significantly over the…
Abstract
Purpose
The purpose of this paper is to investigate the state of the art in static and dynamic games (or inter‐firm relationships). This research area has changed significantly over the last 25 years through the development of phenomena such as the supply chain and the progressive overcoming of monopolistic and oligopolistic frameworks. By exploring the state of the art in inter‐firm relationships, this paper aims to identify the most suitable research methods to be used by future research in this domain and to highlight the major areas under investigation.
Design/methodology/approach
This research adopts both qualitative and quantitative approaches. The qualitative approach describes the technical differences between static and dynamic methods and gives evidence of their appropriateness when applied to a game. Quantitative analysis transforms some of the information extracted from the qualitative analysis into categorical variables in order to obtain an indication of the major issues still to be addressed.
Findings
The resulting findings identify the extent of the use of static and dynamic modelling in previous research and how their use has changed over time, what resolution methods need to be applied when investigating inter‐firm relationship, what features influence this decision and what research areas still remain unexplored.
Originality/value
The existing literature on the modelling of static and dynamic games lacks an exhaustive review. Several contributions investigate the literature on inter‐firms relationships and review numerous issues, but focus only on static or dynamic modelling. This paper fills this gap by reviewing a number of theoretical papers.
Details
Keywords
Chao Wang, Guofu Yin, Zhengyu Zhang, Shuiliang Wang, Tao Zhao, Yan Sun and Dangguo Yang
– The purpose of this paper is to introduce a novel method for developing static aeroelastic models based on rapid prototyping for wind tunnel testing.
Abstract
Purpose
The purpose of this paper is to introduce a novel method for developing static aeroelastic models based on rapid prototyping for wind tunnel testing.
Design/methodology/approach
A metal frame and resin covers are applied to a static aeroelastic wind tunnel model, which uses the difference of metal and resin to achieve desired stiffness distribution by the stiffness similarity principle. The metal frame is made by traditional machining, and resin covers are formed by stereolithgraphy. As demonstrated by wind tunnel testing and stiffness measurement, the novel method of design and fabrication of the static aeroelastic model based on stereolithgraphy is practical and feasible, and, compared with that of the traditional static elastic model, is prospective due to its lower costs and shorter period for its design and production, as well as avoiding additional stiffness caused by outer filler.
Findings
This method for developing static aeroelastic wind tunnel model with a metal frame and resin covers is feasible, especially for aeroelastic wind tunnel models with complex external aerodynamic shape, which could be accurately constructed based on rapid prototypes in a shorter time with a much lower cost. The developed static aeroelastic aircraft model with a high aspect ratio shows its stiffness distribution in agreement with the design goals, and it is kept in a good condition through the wind tunnel testing at a Mach number ranging from 0.4 to 0.65.
Research limitations/implications
The contact stiffness between the metal frame and resin covers is difficult to calculate accurately even by using finite element analysis; in addition, the manufacturing errors have some effects on the stiffness distribution of aeroelastic models, especially for small-size models.
Originality/value
The design, fabrication and ground testing of aircraft static aeroelastic models presented here provide accurate stiffness and shape stimulation in a cheaper and sooner way compared with that of traditional aeroelastic models. The ground stiffness measurement uses the photogrammetry, which can provide quick, and precise, evaluation of the actual stiffness distribution of a static aeroelastic model. This study, therefore, expands the applications of rapid prototyping on wind tunnel model fabrication, especially for the practical static aeroelastic wind tunnel tests.
Details
Keywords
Junan Ji, Zhigang Zhao, Shi Zhang and Tianyuan Chen
This paper aims to propose an energetic model parameter calculation method for predicting the materials’ symmetrical static hysteresis loop and asymmetrical minor loop to improve…
Abstract
Purpose
This paper aims to propose an energetic model parameter calculation method for predicting the materials’ symmetrical static hysteresis loop and asymmetrical minor loop to improve the accuracy of electromagnetic analysis of equipment.
Design/methodology/approach
For predicting the symmetrical static hysteresis loop, this paper deduces the functional relationship between magnetic flux density and energetic model parameters based on the materials’ magnetization mechanism. It realizes the efficient and accurate symmetrical static hysteresis loop prediction under different magnetizations. For predicting the asymmetrical minor loop, a new algorithm is proposed that updates the energetic model parameters of the asymmetrical minor loop to consider the return-point memory effect.
Findings
The comparison of simulation and experimental results verifies that the proposed parameters calculation method has high accuracy and strong universality.
Originality/value
The proposed parameter calculation method improves the existing parameter calculation method’s problem of relying on too much experimental data and inaccuracy. Consequently, the presented work facilitates the application of the finite element electromagnetic field analysis method coupling the hysteresis model.
Details
Keywords
Rongrong Zhang and Yoshio Kanazaki
The purpose of this paper is to test static tradeoff against pecking order models of capital structure in Japanese firms.
Abstract
Purpose
The purpose of this paper is to test static tradeoff against pecking order models of capital structure in Japanese firms.
Design/methodology/approach
The static tradeoff and pecking order models are tested on a sample of 1,325 non‐financial Japanese firms between 2002 and 2006.
Findings
Empirical results prove that both models can explain some part of the capital structure. The static tradeoff model shows that firm leverage is affected by several determinants, and the pecking order model displays similar movements between net debt retired and financial surplus. However, both models have shortcomings. The static tradeoff model fails to explain the negative correlation between profitability and firm leverage, and the pecking order model fails to explain the low deficit coefficient.
Originality/value
The paper, because of the inconsistent results in prior studies, tests static tradeoff against pecking order models, with the data of Japanese firms.
Details
Keywords
Lafaiet Silva, Nádia Félix Silva and Thierson Rosa
This study aims to analyze Kickstarter data along with social media data from a data mining perspective. Kickstarter is a crowdfunding financing plataform and is a form of…
Abstract
Purpose
This study aims to analyze Kickstarter data along with social media data from a data mining perspective. Kickstarter is a crowdfunding financing plataform and is a form of fundraising and is increasingly being adopted as a source for achieving the viability of projects. Despite its importance and adoption growth, the success rate of crowdfunding campaigns was 47% in 2017, and it has decreased over the years. A way of increasing the chances of success of campaigns would be to predict, by using machine learning techniques, if a campaign would be successful. By applying classification models, it is possible to estimate if whether or not a campaign will achieve success, and by applying regression models, the authors can forecast the amount of money to be funded.
Design/methodology/approach
The authors propose a solution in two phases, namely, launching and campaigning. As a result, models better suited for each point in time of a campaign life cycle.
Findings
The authors produced a static predictor capable of classifying the campaigns with an accuracy of 71%. The regression method for phase one achieved a 6.45 of root mean squared error. The dynamic classifier was able to achieve 85% of accuracy before 10% of campaign duration, the equivalent of 3 days, given a campaign with 30 days of length. At this same period time, it was able to achieve a forecasting performance of 2.5 of root mean squared error.
Originality/value
The authors carry out this research presenting the results with a set of real data from a crowdfunding platform. The results are discussed according to the existing literature. This provides a comprehensive review, detailing important research instructions for advancing this field of literature.
Details
Keywords
– The purpose of this paper is to present a methodology for the evaluation of transport aircraft fuselages constructed in a semi-monocoque design.
Abstract
Purpose
The purpose of this paper is to present a methodology for the evaluation of transport aircraft fuselages constructed in a semi-monocoque design.
Design/methodology/approach
A fuselage barrel was computed statically and dynamically using finite element methods. Static analysis was conducted using a global/local approach in which the section loads of the global model were used as load introduction in the local model. Subsequently, a crash analysis was performed, and the results from both disciplines were evaluated by either an optimization or parameter variation algorithm.
Findings
The presented process chain has been developed for use in preliminary design stages to assess aircraft configurations with regard to statics and dynamics. Parameter variation and optimization were conducted, proving functionality of the methodology.
Research limitations/implications
In this early stage of methodology development only one exemplary static load case is considered and the fuselage design is limited to a constant section.
Practical implications
The presented process chain shows an approach to couple different disciplines to reduce the analysis time in aircraft preliminary design phase.
Originality/value
This methodology couples static design and crashworthiness aspects at an early design stage to avoid time- and cost-intensive redesign in subsequent detailed design stages. The process chain introduced in this paper uses a parameterized approach, making this methodology applicable for each fuselage in semi-monocoque design.
Details
Keywords
Grzegorz Drałus and Jerzy Świątek
The purpose of this paper is to present research in the area of the modeling of complex systems using feed‐forward neural network.
Abstract
Purpose
The purpose of this paper is to present research in the area of the modeling of complex systems using feed‐forward neural network.
Design/methodology/approach
Applications of multilayer neural networks with supervisor learning on the own simulator program wrote in Borland® Pascal Language. Series‐parallel identification method is applied. Tapped delay lines (TDL) in static neural networks for modeling of dynamic plants are used. Gradient and heuristic learning algorithms are applied. Three kinds of calibration of learning and testing data are used.
Findings
This paper illustrates that feed‐forward multilayer neural networks can model complex systems. Feed‐forward multilayer neural networks with TDL can be used to build global dynamic models of complex systems. It is possible to compare the quality both models.
Research limitations/implications
The learning and testing data from real systems to tune neuronal models require use of calibrating these data to range 0‐1.
Practical implications
The models quality depends on kind of calibration learning data from real system and depends on kind of learning algorithms.
Originality/value
The method and the learning algorithms discussed in the paper can be used to create global models of complex systems. The multilayer neural network with TDL can be used to model complex dynamic systems with low dynamics.
Details
Keywords
Jonathan B. Dressler and Jeffrey R. Stokes
This paper aims to identify factors that affect agricultural mortgage default and prepayment.
Abstract
Purpose
This paper aims to identify factors that affect agricultural mortgage default and prepayment.
Design/methodology/approach
Using a sample of farm credit system loans, prepayment and default are modeled as competing risks with potentially non‐stationary covariates using a statistical/econometric technique called survival snalysis (SA).
Findings
The analysis suggests that the primary drivers of prepayment and default are the rate of interest charged by the lender at origination and the borrower's current ratio at origination. Tests of the existence of a geographic effect indicate that despite bank management belief to the contrary, branches may not be homogeneous.
Research limitations/implications
This analysis would be improved if more data were available in an easily obtainable manner to control for unobserved heterogeneity. Unobserved heterogeneity or incomplete specification within a model can be problematic. Inferences among regression coefficients can be problematic in that the estimates have inflated variances and unreliable test statistics. In addition, more frequent measures of the time‐varying covariates could be obtained to improve upon the SA models presented above. Future analyses could also incorporate other sections of the agricultural credit association portfolio, as well as a comparison to variable rate notes. One other logical next step would be to obtain loan collateral values to obtain estimates of the exposure at default, and the loss given default, or the estimates needed for the advanced internal ratings based approach described in the Basel Accords.
Originality/value
This paper provides a method for lenders to measure and model mortgage termination, an important consideration for risk managers when determining capital adequacy described in the Basel Accords.
Details
Keywords
The purpose of this paper is to enhance the predictive power of bankruptcy prediction models by taking the past values of firms’ financial ratios as benchmark. For this purpose…
Abstract
Purpose
The purpose of this paper is to enhance the predictive power of bankruptcy prediction models by taking the past values of firms’ financial ratios as benchmark. For this purpose, the paper proposes an indicator variable expressing the time trends of financial ratios.
Design/methodology/approach
The proposed measure uses the minimum and the maximum of financial ratios from the previous period as benchmarks in order to give a more complete picture about the present financial performance of firms. The most popular classification methods of bankruptcy prediction were employed: discriminant analysis, logistic regression, decision trees. Sample specific results and conclusions were avoided by applying tenfold stratified cross-validation.
Findings
The empirical results suggest that the proposed measure can increase the predictive performance of bankruptcy prediction models compared to models based solely on static financial ratios. The results gave evidence for the fact that the firms’ past financial performance is a useful benchmark for evaluating the risk of future insolvency.
Originality/value
The proposed concept is completely new to the literature and practice of bankruptcy prediction. Similar concept has not been published to date. The suggested dynamization approach has three important advantages. It is easy to compute from time series of financial ratios. It is applicable within any classifier irrespective of its mathematical background. The performance of models can be enhanced without the necessity of giving up the interpretability of bankruptcy models, so the proposed measure may play very important role in the practice of credit scoring modeling as well.
Details