Wang Xiaohui, Zhang Xiaoqing and Yang Dasheng
The purpose of this paper is to propose an efficient algorithm for computing the transient responses on wind turbine (WT) towers struck by lightning.
Abstract
Purpose
The purpose of this paper is to propose an efficient algorithm for computing the transient responses on wind turbine (WT) towers struck by lightning.
Design/methodology/approach
The tower is modeled as an electric network and a set of formulas are given for calculating the related electrical parameters. The parameters of grounding rods are also proposed. Based on the numerical representation of the transient characteristics of inductive elements, the electric network is converted into an equivalent circuit. The transient responses are obtained from the equivalent circuit by using circuit analysis method.
Findings
The calculated results are in good agreement with results computed by a hybrid method in frequency and time domain, which demonstrating the validity of the proposed method.
Originality/value
The transient responses on WT towers struck by lightning are computed using the numerical calculation method directly in time domain and electric field, electromagnetic field and induced potentials will be computed from the responses directly, which can provide guidelines for lightning protection design.
Details
Keywords
Dasheng Ji and B. Wade Brorsen
The purpose of this paper is to develop an option pricing model applicable to US options. The lognormality assumption that has typically been imposed with past binomial and…
Abstract
Purpose
The purpose of this paper is to develop an option pricing model applicable to US options. The lognormality assumption that has typically been imposed with past binomial and trinomial option pricing models is relaxed. The relaxed lattice model is then used to determine skewness and kurtosis of distributions of futures prices implied from option prices.
Design/methodology/approach
The relaxed lattice is based on Gaussian quadrature. The markets studied include corn, soybeans, and wheat. Skewness and kurtosis are implied by minimizing the squared deviations of actual option premia from predicted premia.
Findings
Positive skewness is the major source of nonnormality, but both skewness and kurtosis are important as the trinomial model that considers kurtosis has greater accuracy than the binomial model. The out‐of‐sample forecasting accuracy of the relaxed lattice models is better than the Black‐Scholes model in most, but not all cases.
Research limitations/implications
The model might benefit from using option prices from more than one day. The implied skewness and kurtosis were quite variable and using more data might reduce this variability.
Practical implications
Empirical results mostly show positive implied skewness, which suggests extreme price rises were more likely than extreme price decreases.
Originality/value
The relaxed lattice is a new model and the results about implied higher moments are new for these commodities. There are competing models available that should be able to get similar accuracy, so one key advantage of the new approach is its simplicity and ease of use.
Details
Keywords
Vikas Gupta, Shveta Singh and Surendra S. Yadav
Small and medium enterprises (SMEs) play a crucial role in national economies worldwide, generating employment and contributing to innovation. This study tries to investigate the…
Abstract
Purpose
Small and medium enterprises (SMEs) play a crucial role in national economies worldwide, generating employment and contributing to innovation. This study tries to investigate the performance of the newly started IPO platform for the SMEs in India through a two-staged framework developed to measure pre-market and post-market underpricing separately and the impact of economic policy uncertainty (EPU) on the IPO returns using the EPU index which is based on newspaper coverage frequency. Further, the long-run performance of SME IPOs and the factors affecting the same have also been analyzed. The two-staged framework is helpful in capturing the impact of different factors separately on the two distinctive markets and providing effective investment strategies to the investors.
Design/methodology/approach
A sample of 384 SME IPOs issued during 2012–2018 has been analyzed using robust regression analysis.
Findings
The study highlights the fact that there are differences in the factors affecting pre-market and post-market underpricing and reports that investors subscription rate, issue expenses, lead manager reputation and EPU are positively associated, whereas the age of the firm is negatively associated with the pre-market underpricing, and lead manager reputation positively impacts the post-market underpricing whereas issue premium and pre-market underpricing are negatively associated. Pre-market underpricing subsumes all the impact of EPU (publicly available information) in it, hence providing credence to the semi-strong market hypothesis of the Efficient Market Hypothesis (EMH). The long-run performance of SME IPOs increases with time, and lead manager reputation, pre-market and post-market underpricing are positively related to the one-year return whereas issue size, turnover and issue expense are negatively related.
Originality/value
This paper is believed to be the first attempt to analyze the performance of SME IPOs by disaggregating IPO underpricing. The findings of this study will have a great insight for the investors and policymakers.