Abstract
Purpose
This paper aims to describe a numerical simulation method of ice accretion on BO105 helicopter blades for predicting the effects of trailing edge flap deflection on ice accretion.
Design/methodology/approach
A numerical simulation method of ice accretion is established based on Myers model. Next, the shape and location of ice accretion of NACA0012 airfoil are calculated, and a comparison between calculated results and experimental data is made to validate the method. This method is used to investigate the effect of trailing edge flap deflection on ice accretion of a rotor blade.
Findings
The numerical method is feasible and effective to study the ice accretion on helicopter rotor blades. The downward deflection of the trailing edge flap affects the shape of the ice.
Practical implications
This method can be further used to predict the ice accretion in actual flights of the helicopters with multielement airfoils.
Originality/value
The numerical simulation method here can lay a foundation of the research about helicopter flight performance in icing condition through predicting the shape and location of ice accretion on rotor blades.
Details
Keywords
Abstract
Purpose
The purpose of this paper is to reduce the acoustic noise of helicopter ducted tail rotor.
Design/methodology/approach
To predict the noise accurately, a thin-body boundary element method (BEM)/Ffowcs Williams–Hawkings method is developed in this paper. It is a hybrid method combining the BEM with computational aeroacoustics and can be used efficiently to predict the propagation of sound wave in the duct.
Findings
Compared with the experimental results, the proposed method of acoustic noise is rather desirable.
Practical implications
Then several geometry parameters are modified to investigate the noise reduction of ducted tail rotor by using the numerical prediction method.
Originality/value
The aerodynamic and acoustic performance of different modification tasks is discussed. These results demonstrate the validity of design parameters modification of ducted tail rotor in acoustic noise reduction.
Details
Keywords
Various time integration methods and time finite element methods have been developed to obtain the responses of structural dynamic problems, but the accuracy and computational…
Abstract
Purpose
Various time integration methods and time finite element methods have been developed to obtain the responses of structural dynamic problems, but the accuracy and computational efficiency of them are sometimes not satisfactory. The purpose of this paper is to present a more accurate and efficient formulation on the basis of the weak form quadrature element method to solve linear structural dynamic problems.
Design/methodology/approach
A variational principle for linear structural dynamics, which is inspired by Noble's work, is proposed to develop the weak form temporal quadrature element formulation. With Lobatto quadrature rule and the differential quadrature analog, a system of linear equations is obtained to solve the responses at sampling time points simultaneously. Computation for multi-elements can be carried out by a time-marching technique, using the end point results of the last element as the initial conditions for the next.
Findings
The weak form temporal quadrature element formulation is conditionally stable. The relation between the normalized length of element and the suggested number of integration points in one element is given by a simple formula. Results show that the present formulation is much more accurate than other time integration methods and its dissipative property is also illustrated.
Originality/value
The weak form temporal quadrature element formulation provides a choice with high accuracy and efficiency for solution of linear structural dynamic problems.
Details
Keywords
The purpose of this paper is to simulate numerical solutions of nonlinear Burgers' equation with two well‐known problems in order to verify the accuracy of the cubic B‐spline…
Abstract
Purpose
The purpose of this paper is to simulate numerical solutions of nonlinear Burgers' equation with two well‐known problems in order to verify the accuracy of the cubic B‐spline differential quadrature methods.
Design/methodology/approach
Cubic B‐spline differential quadrature methods have been used to discretize the Burgers' equation in space and the resultant ordinary equation system is integrated via Runge‐Kutta method of order four in time. Numerical results are compared with each other and some former results by calculating discrete root mean square and maximum error norms in each case. A matrix stability analysis is also performed by determining eigenvalues of the coefficient matrices numerically.
Findings
Numerical results show that differential quadrature methods based on cubic B‐splines generate acceptable solutions of nonlinear Burgers' equation. Constructing hybrid algorithms containing various basis to determine the weighting coefficients for higher order derivative approximations is also possible.
Originality/value
Nonlinear Burgers' equation is solved by cubic B‐spline differential quadrature methods.
Details
Keywords
Maoliang Bu, ChinTe Lin and Shuwen Zhai
This paper investigates how relative environmental regulation influences the flow of foreign direct investment (FDI), and thereby assesses the pollution haven hypothesis (PHH). In…
Abstract
This paper investigates how relative environmental regulation influences the flow of foreign direct investment (FDI), and thereby assesses the pollution haven hypothesis (PHH). In this field, conflicting results exist, partly due to the mere consideration of absolute environmental regulation or the inadequate consideration of endogeneity. Concerning these, we study China’s inward FDI from 26 developed countries and 12 developing countries over 1996–2009, and collect four different environmental regulation indicators at relative values of CO2, SO2, PM10, and an environmental regulation index. Using an instrumental variable approach, we find strong PHH evidence no matter for the subsample of FDI from developed countries or the one from developing countries. Moreover, we show how such results can be masked if failing to consider the endogeneity.
Details
Keywords
Lisa Maria Beethoven Steene, Lisa Gaylor and Jane L. Ireland
The current review aims to focus on how risk and protective factors for self-harm in secure mental health hospitals are captured in the literature.
Abstract
Purpose
The current review aims to focus on how risk and protective factors for self-harm in secure mental health hospitals are captured in the literature.
Design/methodology/approach
Fifty-seven articles were included in a systematic review, drawn from an initial 1,119 articles, post duplicate removal. Databases included Psycinfo, Psycarticles, Psycnet, Web of Science and EBSCO host. A thematic analysis was used, which included a meta-ethnographic approach for considering qualitative papers.
Findings
There was a clear focus on risk factors, with eight identified (in order of occurrence): raised emotional reactivity and poor emotion regulation; poor mental health; traumatic experiences; personality disorder diagnosis and associated traits; increased use of outward aggression – dual harm; constraints of a secure environment and lack of control; previous self-harm and suicide attempts; and hopelessness. Protective factors featured less, resulting in only three themes emerging (in order of occurrence): positive social support and communication; positive coping skills; and hope/positive outlook.
Research limitations/implications
This includes a proposal to move focus away from “risk” factors, to incorporate “needs”, in terms of individual and environmental factors. There is also a need for more attention to focus on developing high quality research in this area.
Originality/value
The research captures an area where a synthesis of research has not been comprehensively undertaken, particularly with regards to capturing protective as well as risk factors.
Details
Keywords
The purpose of this paper is to present some modifications in the spline‐based differential quadrature method (DQM), in order to accelerate the convergence of the method. The…
Abstract
Purpose
The purpose of this paper is to present some modifications in the spline‐based differential quadrature method (DQM), in order to accelerate the convergence of the method. The improvements are explained and examined by the examples of the free vibration of conical shells. The composite laminated shell, as well as isotropic one, are taken under consideration.
Design/methodology/approach
To determine weighting coefficients for the DQM, the spline interpolation with non‐standard definitions of the end conditions is used. One of these definitions combines natural and not‐a‐knot end conditions, while the other one uses the boundary conditions for considered problem as the end conditions. The weighting coefficients can be determined by solving set of equations arising from spline interpolation.
Findings
It is shown that the proposed modifications significantly improve the convergence of the method, especially when the boundary conditions are introduced at the stage of the computation of the weighting coefficients. Unfortunately, the use of this approach is limited to some types of boundary conditions.
Originality/value
The paper describes development of the modified spline interpolation dedicated to DQM and examines the possibility of building boundary conditions into the weighting coefficients at the stage of the computation of these coefficients.
Details
Keywords
Cubic B‐spline differential quadrature methods have been introduced. As test problems, two different solutions of advection‐diffusion equation are chosen. The first test problem…
Abstract
Purpose
Cubic B‐spline differential quadrature methods have been introduced. As test problems, two different solutions of advection‐diffusion equation are chosen. The first test problem, the transportion of an initial concentration, and the second one, the distribution of an initial pulse, are simulated. The purpose of this paper is to simulate the test problems.
Design/methodology/approach
The cubic B‐spline functions are chosen as test functions in order to construct the differential quadrature method. The error between the numerical solutions and analytical solutions are measured using various error norms.
Findings
The cubic B‐spline differential quadrature methods have produced acceptable solution for advection‐diffusion equation.
Originality/value
The advection‐diffusion equation has never been solved by any differential quadrature method based on cubic B‐splines.
Details
Keywords
Wu Yan and Lisa Catherine Ehrich
The purpose of this paper is to provide an understanding of principal preparation and training in China by providing a background discussion of principal preparation in a number…
Abstract
Purpose
The purpose of this paper is to provide an understanding of principal preparation and training in China by providing a background discussion of principal preparation in a number of countries. As an illustration, it provides an overview of the curriculum used in the initial preparation of school principals at Beijing Normal University.
Design/methodology/approach
The paper draws mainly on writing and research from China, Australia and the USA to explore principal preparation and training in China.
Findings
In addition to providing a rich description of principal preparation in China, the paper's main findings comprise seven key challenges that confront China as it endeavours to provide quality principal preparation. These challenges include China's diversity and uneven social, cultural and educational development; limited resources in some regions throughout China; the place and importance of study tours for principal preparation; the teaching approach used to train principals; the process used for assessing principal learning during their training programs; the limited transfer of learning from the classroom to the school environment; and the timing of training for principals.
Practical implications
Each of the challenges arising here raises important practical implications for developers of principal training programs.
Originality/value
The paper paints a picture of principal preparation in China and raises a number of issues and challenges with which it continues to grapple. Of note is that China is not alone in facing some of these ongoing concerns.