η method of numerical integration

In the finite element dynamic analysis, the governing partial differential equations are first discretized in space and then the resulting equations are integrated with respect to time. The time integration is an important aspect of the entire analysis since efficiency, economy and accuracy of the solution depends on it, to a large extent. In this paper, a new one step implicit algorithm known as method suitable for wave propagation problems is introduced. The proposed algorithm includes a term defining an impulse load vector which permits the use of time increments that can be controlled solely by accuracy requirements. The stability and accuracy characteristics of the proposed method are compared with those of the other available methods.     

σ-ε-Design method

RILEM Technical CommitteesRILEM TC 162-TDF: Test and Design Methods for Steel Fibre Reinforced Concrete Recommendations

σ-ε-Design method     

Abelès method revisited

The Abelès method is a classical method for determining the refractive index of dielectric thin films. In this paper we examine the main features of the method in a formal manner, using closed-form equations, and we show that the method is ambiguous in certain yet unreported situations.     

DASCO — a new classification method

Frank, I.E., 1988. DASCO — a new classification method. Chemometrics and Intelligent Laboratory Systems, 4: 215-222.A new classification method, called DASCO, is introduced and compared with discriminant analysis and SIMCA. After discussing the algorithmic similarities and differences of the three methods, their predictive capabilities are examined in a simulation study of 24 different data sets. Finally DASCO's performance is demonstrated on some chemical classification problems.     

Novel method to produce β-TCP scaffolds

The production of ceramic scaffolds by a novel method was reported in this work. The method comprised the mixture of colloidal silica and β-tricalcium phosphate (β-TCP) powder, where paraffin microspheres were further added to provide the porosity in the scaffold after firing. Thermo-gravimetric analysis showed that the paraffin was completely degraded before 550 °C, where the heat treatment at 1100 °C was enough to remove the paraffin and provide porosity and mechanical strength. The scaffold had an open porosity, but with poor pore interconnection. The density of the scaffold was 1.11 ± 0.03 g/cm³ with a porosity of 64.98 ± 1.1%, and the compression strength was 5.02 ± 1.2 MPa.     

Fuzzy α-discounting method for multi-criteria decision-making

The α-Discounting Method was developed to be an alternative to and extension of the Analytical Hierarchy Process (AHP) to solve multi-criteria decision-making (MCDM) problems with non-commensurable and conflicting criteria. In contrast to the AHP, this method works not only for pairwise comparisons but also for n-wise comparisons if relative importance of criteria can be expressed in a system of linear homogenous equations. This method also has a comparative advantage as it can transform those MCDM problems, classified as inconsistent by the AHP, into a consistent form. This study briefly compares the two methods and then develops the Fuzzy α-Discounting Method for Multi-Criteria Decision Making (Fα-DM MCDM). Two illustrative fuzzy MCDM problems from the literature have been solved to show how the Fα-DM MCDM works.     

Hydroxyapatite–zirconia composites preparedby precipitation method

Chemical routes to prepare ceramic precursor powders are frequently envisaged, especially when the aspects related to the microstructure are important and need to be controlled. An understanding of which parameters of synthesis and thermal treatment can influence the mechanical properties of hydroxyapatite compounds is essential for the production of such materials. Hydroxyapatite–zirconia composites have been prepared, in this study, by a precipitation method. This led to the formation of homogeneous powders with a very defined particle-size distribution. Ceramic pellets prepared from these powders were easily compacted and sintered without cracking. As expected, the presence of the zirconia phase improved composite densities and appeared to have an important role in thermal stabilization of the hydroxyapatite phase.     

A meshfree method: meshfree weak–strong (MWS) form method,for 2-D solids

A novel meshfree weak–strong (MWS) form method is proposed based on a combined formulation of both the strong-form and the local weak-form. In the MWS method, the problem domain and its boundary is represented by a set of distributed points or nodes. The strong form or the collocation method is used for all nodes whose local quadrature domains do not intersect with natural (Neumann) boundaries. Therefore, no numerical integration is required for these nodes. The local weak-form, which needs the local numerical integration, is only used for nodes on or near the natural boundaries. The locally supported radial point interpolation method and the moving least squares approximation are used to construct the meshfree shape functions. The final system matrix will be sparse and banded for computational efficiency. Numerical examples of two-dimensional solids are presented to demonstrate the efficiency, stability, accuracy and convergence of the proposed meshfree method.     

Through-thickness strength measurements using Arcan’s method

This paper presents results obtained from the experimental study on the behaviour of glass/epoxy butterfly-shaped specimens tested under pure shear and biaxial loadings using an Arcan device. Notch-to-notch longitudinally and perpendicularly oriented fibre specimens, respectively referred to as Mat31 and Mat32 ones have been tested with different loading angles ranging from 0° to 90°. The fracture mode was more or less repetitive for Mat31 specimens whereas it depended on the loading direction for Mat32 type, for which the number of cracks and the obliqueness relative to the notch-to-notch line, decreased as the test angle increased. The comparison of failure envelopes has demonstrated that Mat31 specimens are much more resistant whatever the loading angle. However, strengths at failure of Mat32 type are in good agreement with Hashin’s failure criterion, for pure shear tests up to 30° loading angles. Mat31 specimens’ failure stresses were overestimated by the criterion, although similarities in trends were noticed.     

Eigenvalue analysis for acoustic problem in 3D by boundary element method with the block Sakurai–Sugiura method

This paper presents accurate numerical solutions for nonlinear eigenvalue analysis of three-dimensional acoustic cavities by boundary element method (BEM). To solve the nonlinear eigenvalue problem (NEP) formulated by BEM, we employ a contour integral method, called block Sakurai–Sugiura (SS) method, by which the NEP is converted to a standard linear eigenvalue problem and the dimension of eigenspace is reduced. The block version adopted in present work can also extract eigenvalues whose multiplicity is larger than one, but for the complex connected region which includes a internal closed boundary, the methodology yields fictitious eigenvalues. The application of the technique is demonstrated through the eigenvalue calculation of sphere with unique homogenous boundary conditions, cube with mixed boundary conditions and a complex connected region formed by cubic boundary and spherical boundary, however, the fictitious eigenvalues can be identified by Burton–Miller's method. These numerical results are supported by appropriate convergence study and comparisons with close form.     

A heuristic 0–1 integer programming method

Summary In this paper, we present a novel relaxation method for the integer programming problem:Ax=b,A {–1,0,+1}^m×N,x {0,1}^N, N>m. The report includes experimental results of problems with up tom=100 equations andN=400 variables.     

创造思维方法(method for creative thought)

亦即创造性思维方法 ,是破除传统思维定势的束缚之后获得创造文明、或者能正确解决问题的思维方法。创造思维有时又称之为创造性劳动 ,可以分为科学创造思维和一般创造思维创造思维方法(method for creative thought)     

Modeling brittle–ductile failure transition with meshfree method

In this work, the element-free Galerkin (EFG) method is used to simulate the transition from brittle to ductile failure under finite deformation. A Galerkin formulation incorporating the Johnson–Cook damage model is implemented in numerical simulations. The constitutive update and the cracking method incorporated in the EFGM are described. Numerical simulations are compared with the experimental results performed by Kalthoff et al. They show that the proposed meshfree algorithm works well and it is confirmed that the proposed method provides a convenient and yet accurate means for study of failure transition.     

Flexibility-based structural damage identification using Gauss–Newton method

Structural damage will change the dynamic characteristics, including natural frequencies, modal shapes, damping ratios and modal flexibility matrix of the structure. Modal flexibility matrix is a function of natural frequencies and mode shapes and can be used for structural damage detection and health monitoring. In this paper, experimental modal flexibility matrix is obtained from the first few lower measured natural frequencies and incomplete modal shapes. The optimization problem is then constructed by minimizing Frobenius norm of the change of flexibility matrix. Gauss–Newton method is used to solve the optimization problem, where the sensitivity of flexibility matrix with respect to structural parameters is calculated iteratively by only using the first few lower modes. The optimal solution corresponds to structural parameters which can be used to identify damage sites and extent. Numerical results show that flexibility-based method can be successfully applied to identify the damage elements and is robust to measurement noise.     

Phase-shifting moireí method with an atomic force microscope

Using a phase-shifting technique with an atomic force microscope (AFM), we propose a phase-shifting AFM scanning moiré method. The phase shifting is realized in four steps from 0 to 2pi by a piezoscanner in the AFM. The measurement method and experimental techniques are described in detail. For demonstration this method is applied to determine the phase distribution in the AFM moiré of a 1200-line/mm holographic grating used to measure the thermal deformation in a Quad FlatPack electronic package.     

A new method for measuring the shape and size of the plastic zones around slit ends — the direct showing method

The direct showing method is a new method for measuring the plastic zones by using photoelastic coating technique. An experimental study for the plastic zones of four kinds of metal thin plate tensile specimens containing slits has been made by the method. Some typical experimental results and primary knowledge have been given in this paper. Non-symmetrical isochromatic fringe patterns and plastic zones were observed in annealed B3 thin steel plate specimens. This non-symmetrical phenomenon is well worth further research.     

Direct meshless local Petrov–Galerkin method for elastodynamic analysis

This article describes a new and fast meshfree method based on a generalized moving least squares (GMLS) approximation and the local weak forms for vibration analysis in solids. In contrast to the meshless local Petrov–Galerkin method, GMLS directly approximates the local weak forms from meshless nodal values, which shifts the local integrations over the low-degree polynomial basis functions rather than over the complicated MLS shape functions. Besides, if the method is set up properly, all local integrals have the same value if all local subdomains have the same shape. These features reduce the computational costs, remarkably. The new technique is called direct meshless local Petrov–Galerkin (DMLPG) method. In DMLPG, the stiff and mass matrices are constructed by integration against polynomials. This overcomes the main drawback of meshfree methods in comparison with the finite element methods (FEM). The Newmark scheme is adapted as a time integration method, and numerical results are presented for various dynamic problems. The results are compared with the exact solutions, if available, and the FEM solutions.     

Preparation of chitosan–hyaluronate double-walled microspheres by emulsification-coacervation method

Chitosan (CHS)−hyaluronate (HA) double-walled microspheres were prepared by emulsification-coacervation method. Tripolyphosphate (TPP) acted as ion crosslinker. The effects of oil/water volume ratio, surfactant, solution pH, TPP concentration, HA concentration, and emulsification time on microspheres fabrication and morphology were examined by Zeta (ζ) potential, Scanning electron microscopy (SEM) and Fourier-transform infrared spectrometry (FT-IR). It was found that TPP concentration, solution pH, surfactant and emulsification time were crucial factors for microspheres fabrication. Spherical microspheres with smooth surface were formed when TPP concentration was 8% or higher. The optimal pH for microspheres formation ranged from 6.0 to 7.0. As for surfactant, the microspheres obtained when span80 was applied alone were shapelier compared with those obtained when both span80 and tween80 were applied. With insufficient emulsification time, vacuous microcapsules, but not compact microspheres were formed. In addition, oil/water volume ratio and HA concentration also affected the microspheres morphology, but less importantly.     

A new active error compensatory method of machinery accuracy†

A new active error compensatory method for on-line cutting control has been developed for reduction of the form errors in machining. This approach is a combination of in-process gauging and model active compensatory control. In this approach, there are two features of substantial importance: stochastic modelling and optimum forecasting. Through stochastic modelling, the cutting tool error motions can be represented by a simple model without the necessity of obtaining the complex cause-and-effect relationships between various errors and error sources, and more importantly, it is possible to account for both repeatable and non-repeatable parts of errors. Optimum forecasting is an important prerequisite for a rational control strategy, considering the inevitable time delay associate with sensing, computation and actuation. The proposed control method was implemented for the control of cylindricity in boring operations. Through the controller simulation based on experimental measurements, the improvement in cylindricity accuracy confirms the effectiveness of this proposed strategy