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The discrete element method (DEM) was used to stimulate creep processes in granular materials. The authors present the main features of the numerical model, which include a new viscous mechanism for particle sliding, a new feedback technique for maintaining constant stress during creep, and a scaling technique that allowed monitoring the long‐term creep behaviour of a granular assembly. The creep behaviour of the numerical model exhibited the essential characteristics of soil creep—a creep rate that decreased rapidly with time, an increase in the creep rate with the applied deviator stress, and the beginning of creep rupture. The model's numerical performance is discussed, and representative results are presented.

A new contact detection technique for discrete element modeling is described. This technique is suitable for a large family of particle shapes that are based on the dilation process from mathematical morphology. In the dilation process an arbitrary shape is dilated by placing the center of a sphere of fixed diameter at every point in the basic shape. Defining a contact between two objects in this class is equivalent to determining which spheres amongst the infinite number that compose each object is in contact. The algorithm is derived for general ellipsoidal particles and demonstrated with a series of biaxial deformation simulations using a range of ellipsoidal particle shapes.

The paper reviews existing empirical research where long-term performance (LTP) of firms is the dependent variable. The purpose of this paper is to structure and classify the existing research, outline the shortcomings, and chart the avenues for future research in the area of LTP.

The paper is a review of the existing empirical literature. It surveys the existing studies and proposes new directions of empirical research.

The paper argues that there is a disconnection between the principal theories in strategy and the existing empirical findings. In particular, while the resource-based view (RBV) and dynamic capabilities view aim to predict sustainable competitive advantage and sustainable firm performance, few empirical papers examine the LTP consequences of resources and dynamic capabilities.

The paper shows where future research efforts should be concentrated by outlining shortcomings in existing research.

The paper compares ways to measure LTP that will be useful to corporate executives. The paper also outlines factors that have been shown to affect LTP. These findings can be used by executives planning their strategy.

The paper is a first review of LTP. It also contributes to the debate in strategy on the RBV and dynamic capabilities.

In the first part of this series of papers on the combined finite/discrete element simulation of shot peening processes, different contact interaction laws for 2D cases are extensively studied with special attention given to the proper selection of the parameter values involved, which is one of the key issues for successful direct simulation. In addition, computational issues including contact forces, partial contact, energy dissipation, and rheological representation are addressed. Numerical examples for a single shot impact system simulated by the coupled finite/discrete element method using different interaction laws are provided to verify the proposed approaches. The results are also compared with those obtained by using only finite element methods. Findings obtained by performing 2D simulations will, in the subsequent article, be used in realistic computational simulations of 3D shot peening processes.

Discrete element methods are numerical procedures for simulating the complete behaviour of systems of discrete, interacting bodies. Three important aspects of discrete element programs are examined: (1) the representation of contacts; (2) the representation of solid material; and (3) the scheme used to detect and revise the set of contacts. A proposal is made to define what constitutes a discrete element program, and four classes of such programs are described: the distinct element method, modal methods, discontinuous deformation analysis and the momentum‐exchange method. Several applications and examples are presented, and a list is given of suggestions for future developments.

The aim of this chapter is to help library administrators understand the concept of Service Design, and to maintain that any consideration of the future of library spaces should begin with a service design focused approach.

The chapter is a combination of general review, literature review, case study, and conceptual paper. It focuses on describing the basics of the concept, highlighting essential resources for further understanding, highlighting service design specifically applied in libraries, and providing one case study of an academic library undergoing a master planning project utilizing the lens of Service Design. The chapter will conclude by emphasizing the importance of attaining an appropriate understanding and buy-in for the Service Design process by library administrators and staff in order for its effective implementation.

Practical implications to employing Service Design to library spaces are endless, and span that gamut from making smart decisions based on user input and evidence, to creating spaces and services that are relevant to library users. Employing a Service Design approach to library building projects helps administrators position themselves to advocate for needed technology and funding in the highly competitive resource arena. The ideas gleaned from this chapter can be applied in any library: academic, public, special, or school. The results will be different, because every library has a unique group of users, but the processes employed are the same.

Library literature related to Service Design is slim but slowly emerging. This chapter fills a gap in literature geared specifically to administrators as well as building design and redesign projects.

Application of the discrete element method (DEM) to real scale engineering problems involving three‐dimensional modelling of large, non‐spherical particles must consider the inertia tensor and temporal change in the orientation of the particles when calculating the rotational motion. This factor has commonly been neglected in discrete element modelling although it will significantly influence the dynamic behaviour of non‐spherical particles. In this paper two methods, vector transformation and tensor transformation, for calculation of the rotational motion of particles in response to applied moments are presented. The methods consider the inertia tensor and the local object frame of arbitrary shaped particles and suggest solutions for the non‐linear Euler equations for calculation of their rotational motion. They are discussed with respect to implementation into a discrete element code and assessed in terms of their accuracy and computational efficiency.

A general overview is presented on applications of the discrete element method (DEM) to granular media. A literature survey is performed of static and dynamic simulations using random arrays of compliant particles, and forty‐two references published mostly in the last ten years are identified and categorized according to a number of relevant criteria. It is concluded that the interest in the use of the technique is rapidly increasing in the research and engineering community, with applications concentrated in soil mechanics, rock mechanics, grain flow and engineering problems. Additional studies and verifications of some numerical aspects of the DEM technique are suggested including parametric studies and comparisons. Program CONBAL‐2 (CONTACT + TRUBAL in 2D) developed by the authors based on TRUBAL created by Strack and Cundall, is described. CONBAL‐2 uses the complete Mindlin solution for the contact between two spheres and thus can be used for small strain and cyclic loading. The program is applied to study the cyclic response of uniform, medium dense to dense rounded quartz sand. Cyclic strain‐controlled loading at constant volume is applied to isotropically consolidated, random arrays of 531 spheres, using cyclic strains ranging from 10–4% to 10–1%. The calculated shear modulus, Gmax, constrained modulus, D, and Poisson's ratio at small strains are correlated with the confining pressure, the porosity of the array, and the coordination number. The calculated variations of secant modulus and damping ratio with cyclic strain compare favourably with the experimental results on sands compiled by Seed and Idriss. Finally, ‘pore water pressure buildup’ and cyclic stiffness degradation of the material with number of cycles is calculated at a cyclic strain of 10–1%, and the prediction is found to represent closely cyclic undrained experiments on sands. The existence of a threshold strain, yt ≈ 10–2%, found experimentally, is also predicted by the simulations.

Though the problem of resolving translational motion in particle methods is a relatively straightforward task, the complications of resolving rotational motion are non‐trivial. Many molecular dynamics and non‐deformable discrete element applications employ an explicit integration for resolving orientation, often involving products of matrices, which have well‐known drawbacks. The purpose of this paper is to investigate commonly used algorithms for resolving rotational motion and describe the application of quaternion‐based approaches to discrete element method simulations.

Existing algorithms are compared against a quaternion‐based reparameterization of both the central difference algorithm and the approach of Munjiza et al. for finite/discrete element modeling (FEM/DEM) applications for the case of torque‐free precession.

The resultant algorithms provide not only guaranteed orthonormality of the resulting rotation but also allow assumptions of small‐angle rotation to be relaxed and the use of a more accurate Taylor expansion instead.

The approaches described in this paper balance ease of implementation within existing explicit codes with computational efficiency and accuracy appropriate to the order of error in many discrete element method simulations.