Search results

This paper extends the linear complementarity problem formulation of [7] and [8] for normal impact of planar deformable bodies in multibody systems. In the kinematics of impact we consider the normal gaps between the impacting bodies in terms of the generalized coordinates. Then, the generalized coordinate’s vector is formulated in terms of the impact forces using the 5th order implicit Runge‐Kutta approach RADAU5. Substituting the generalized coordinates in the relation of normal gaps together with the complementarity relations of unilateral contact constraints leads to a linear complementarity problem where its solution results in the solution of the impact problem including impact forces and normal gaps. Then, alternatively another formulation on velocity level based on the 4th order explicit Runge‐Kutta is presented. In the presented approach no coefficient of restitution is used for treatment of energy loss during impact and, instead, the material damping is responsible for energy loss. A good agreement between the results of our approach with the results of FEM for soft planar deformable bodies was shown in [7]. Here, we improve the results for stiff planar deformable bodies and show that with a proper selection of eigenmodes, the results on both position and velocity level approach the precise results of FEM provided that an optimal time step of the integration is chosen. We also investigate the effect of considering material damping and some higher eigenfrequencies on the amount of energy which is dissipated during impact based on our approach.

The tensile test is one of the fundamental experiments used to evaluate material properties. Simulating a tensile test can be a replacement of experiments to determine mechanical parameters of a continuous material. The paper aims to discuss these issues.

This research uses a new approach to model a tensile test of a high-carbon steel on the basis of discrete element method (DEM). In this research, the tensile test specimen was created by using a DEM packing theory. The particle-particle bond model was used to establish the internal forces of the tensile test specimen. The particle-particle bond model was first tested by performing two-particle tensile test, then was adopted to simulate tensile tests of the high-carbon steel by using 3,678 particles.

This research has successfully revealed the relationships between the DEM parameters and mechanical parameters by modelling a tensile test. The parametric study demonstrates that the particle physical radius, particle contact radius and bond disc radius can significantly influence ultimate stress and Young’s modulus of the specimen, whereas they slightly impact elongation at fracture. Increasing the normal and shear stiffness, the critical normal and shear stiffness can enable the increase of ultimate stress, however, up to maximum values.

To improve the particle-particle bond model to simulate a tensile test for high-carbon steel, the damping factors for compensating energy loss from transition of particle motions and failure of bonds are required.

This work reinforces the knowledge of applying DEM to model continuous materials.

This research illustrates a new approach to model a tensile test of a high-carbon steel on the basis of DEM.

The purpose of this paper is to construct a continuous time series model to study the thermal creep of rough surfaces in contact.

For normal loading, the contact between rough surfaces can often be modeled as the contact of an effective surface with a rigid fiat surface. A solution for the deformation of such equivalent surface, generated using fractal geometry, can be modified. However, in this study only the case of a single rough surface in contact with a rigid flat surface is considered. In the interface, the material is assumed to follow the idealized constitutive viscoelastic standard linear solid (SLS) model. Fractal geometry, through Cantor set theory, is utilized to model the roughness of the surface.

An asymptotic time series power law is obtained, which associates the creep load, the buck temperature and the creep of the fractal surface.

This law is only valid as long as the creep is of the size of the surface roughness. The modified model admits an analytical solution for the case when the behavior is linear viscoelastic. The proposed model shows a good agreement when compared with experimental results available in the literature.

The purpose of this paper is to analyze how strategic renewal affects the reconfiguration of capabilities. In the context of organizational change in a large utility firm, we examine the evolution of the capability structure, and explain the emergence and persistence of capability gaps.

The paper uses an inductive multiple case study methodology to compare four processes of capability reconfiguration at Eskom, South Africa's electricity supplier.

The results show that strategic renewal unfolds through different processes, which vary in their impact. Some processes have an immediate effect in closing capability gaps. The impact of others is with a significant time lag. Most critical, however, are processes that widen capability gaps. As a result, firms may face severe and persistent performance deficiencies.

Prior research has only marginally addressed the relationship between strategic renewal and capability reconfiguration, and has largely neglected emerging capability gaps.

Strategic renewal may cause unintended crowding out effects of specific capabilities. Managers need to consider these potential implications of strategic renewal.

Understanding the challenges of how to improve the performance of utility services is crucial for economic development, welfare and social inclusion.

This study importantly highlights that the emergence of capability gaps is a common phenomenon rather than an exception in strategic renewal processes. The findings contribute to the strategic renewal literature and to management research in infrastructure sectors.

Neuroarchitecture is a new interdisciplinary research field combining neuroscience and architecture that has developed and expanded since 2000. Neuroarchitecture originated from the divergence of previous multidisciplinary studies on the relationship between humans and the environment. However, scoping reviews of neuroarchitecture in relation to the experience of the built environment are lacking. Thus, this study aimed to provide the background and research trends of neuroarchitecture to contribute to discussions on the built environment.

A general form of scoping review was adopted, following the PRISMA-ScR checklist. For this scoping review emphasizing the embodied implication of neuroarchitecture for the built environment, an evaluation framework was developed consisting of four categories: health, performance, aesthetics and emotion.

This study explores objective techniques, including electroencephalography and functional magnetic resonance imaging, electrocardiogram, electrodermal activity and saliva cortisol, to measure neurophysiological impacts, adopting real, virtual and images of environmental settings. An in-depth review of 25 selected papers revealed the existing empirical research on neuroarchitecture using human physiological measurement tools and representational environment settings to examine the impact of human–environment relationships.

A meta-analysis of theoretical and intervention studies on neuroarchitecture that investigates the multisensory characteristics of the environment is lacking. In addition, the development and application of wearable tools to meet the needs of real environment settings can improve the effectiveness of neurophysiological measurement tools.

Architectural history is the fundamental resource that informs the essence of architecture and design thinking; however, education does not appear to link history to design thinking. A study of architectural history textbooks reveals the inadequacy of relying on the modern paradigm and architecture's typology of styles and periods. Instead, conceptual metaphor theory is recommended as the framework for understanding architectural history from an experiential approach. This study aims to complement architectural history by a new understanding of embodied cognition in generating paradigm change.

This study reviewed architectural history through changing body metaphors in terms of embodied experience. The study examined three different metaphorical structures of the body – nature, machine and neural network – projected on the built environment and experienced in accordance with three periods of architectural history, which are categorized as before modern, modern and after modern.

As a result of the case study, ancient pyramids can attain more empirical meaning as playful spaces than abstract forms, Greek temples as social spaces than symbolic spaces, medieval churches as atmospheric spaces than visually-centric spaces, modern residential buildings as unsustainable machines and contemporary parks as raising awareness of sustainable environment.

Therefore, this article contributes to understandings and knowledge of how built environments are experienced from the perspective of a neural network, to the development of a pedagogical alternative to traditional architectural history, to linking architectural history to design and practice to re-establish the importance and vitality of architectural history and finally to creating a sustainable didactic.

The term architectural management has been in use since the 1960s and forms an essential part of this journal's title. However, the evolution of the architectural management field has not been a smooth affair, coming into, out of, and then back into fashion; and concise definitions continue to be illusive. Architectural management is a powerful tool that can be applied to the benefit of the professional service firm and the total building process, yet it continues to receive scant attention in the professional journals, seen as little more than a specialist interest. This paper charts the development of the architectural management field and takes a critical look at the field in relation to current research and its applicability to those who stand to gain the most from architectural management, the professional service firms. The paper concludes that architectural management is a cultural issue.

The purpose of this paper is to present a methodology for parallel simulation that employs the discrete element method (DEM) and improves the cache performance using Hilbert space filling curves (HSFC).

The methodology is well suited for large-scale engineering simulations and considers modelling restrictions due to memory limitations related to the problem size. An algorithm based on mapping indexes, which does not use excessive additional memory, is adopted to enable the contact search procedure for highly scattered domains. The parallel solution strategy uses the recursive coordinate bisection method in the dynamical load balancing procedure. The proposed memory access control aims to improve the data locality of a dynamic set of particles. The numerical simulations presented here contain up to 7.8 millions of particles, considering a visco-elastic model of contact and a rolling friction assumption.

A real landslide is adopted as reference to evaluate the numerical approach. Three-dimensional simulations are compared in terms of the deposition pattern of the Shum Wan Road landslide. The results show that the methodology permits the simulation of models with a good control of load balancing and memory access. The improvement in cache performance significantly reduces the processing time for large-scale models.

The proposed approach allows the application of DEM in several practical engineering problems of large scale. It also introduces the use of HSFC in the optimization of memory access for DEM simulations.

The purpose of this paper is to investigate the dissipative filtering problem for a flexible manipulator (FM) with randomly occurring uncertainties and randomly occurring missing data.

The randomly occurring phenomena during the filtering procedure are described by Bernoulli sequences. Based on the idea of dissipative theory, the distributed filtering error augmented system is derived for ensuring the prescribed dissipative performance.

By constructing appropriate Lyapunov function, sufficient dissipative filtering conditions are derived such that the filtering error can be approaching zero. Then, the desired distributed filter gains are designed with the help of matrix transformation.

The merit of this paper is proposing a novel distributed filtering framework for an FM with external disturbance under the dissipative framework, which can provide a more applicable filter design.

This work aims at constructing a continuous mathematical, linear elastic, model for the thermal contact conductance (TCC) of two rough surfaces in contact.

The rough surfaces, known to be physical fractal, are modelled using a deterministic Cantor structure. Such structure shows several levels of imperfections and including, therefore, several scales in the constriction of the flux lines. The proposed model will study the effect of the deformation (approach) of the two rough surfaces on the TCC as a function of the remotely applied load.

An asymptotic power law, derived using approximate iterative relations, is used to express the area of contact and, consequently, the thermal conductance as a function of the applied load. The model is valid only when the approach of the two surface in contact is of the order of the surface roughness. The results obtained using this model, which admits closed form solution, are displayed graphically for selected values of the system parameters; the fractal surface roughness and various material properties. The obtained results showed good agreement with published experimental results both in trend and the numerical values.

The model obtained provides further insight into the effect that surface texture has on the heat conductance process. The proposed model could be used to conduct an analytical investigation of the thermal conductance of rough surfaces in contact. This model, although simple (composed of springs), nevertheless works well.