A first order system least squares method for the Helmholtz equation

We present a first order system least squares (FOSLS) method for the Helmholtz equation at high wave number k, which always deduces Hermitian positive definite algebraic system. By utilizing a non-trivial solution decomposition to the dual FOSLS problem which is quite different from that of standard finite element method, we give error analysis to the hp-version of the FOSLS method where the dependence on the mesh size h, the approximation order p, and the wave number k is given explicitly. In particular, under some assumption of the boundary of the domain, the L2 norm error estimate of the scalar solution from the FOSLS method is shown to be quasi optimal under the condition that kh/p is sufficiently small and the polynomial degree p is at least O(\log k). Numerical experiments are given to verify the theoretical results

Knowledge management, absorptive capacity and organisational culture: A case study from Chinese SMEs

Copyright © 2008 Inderscience Enterprises Ltd. This is the author's accepted manuscript. The final published article is available from the link below.Based on the analysis of an innovative medium sized enterprise from mainland China, this paper investigated the Knowledge Management (KM) issues by focusing on its KM enablers and process. This paper attempts to investigate how Chinese enterprises absorb knowledge from external sources; how they developed culture to facilitate Knowledge Management Processes (KMPs) and what major challenges they raise for the future by looking at the case study of a Chinese Small and Medium-sized Enterprises (SMEs). The case study indicates that Chinese enterprises emphasised knowledge acquisition and the capacities of knowledge absorption, application, creation, sharing and integration as vital to sustaining competitive advantage for these firms. Corporative organisational culture also has significant impact on the KM in those enterprises

Learning Single-Image Depth from Videos using Quality Assessment Networks

Depth estimation from a single image in the wild remains a challenging problem. One main obstacle is the lack of high-quality training data for images in the wild. In this paper we propose a method to automatically generate such data through Structure-from-Motion (SfM) on Internet videos. The core of this method is a Quality Assessment Network that identifies high-quality reconstructions obtained from SfM. Using this method, we collect single-view depth training data from a large number of YouTube videos and construct a new dataset called YouTube3D. Experiments show that YouTube3D is useful in training depth estimation networks and advances the state of the art of single-view depth estimation in the wild

Critical knowledge management factors and organizational performance: An investigation of Chinese hi-tech enterprises

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 28/05/2008.This study sets out to explore the critical factors of knowledge management (KM) that impact on the organizational performance of Chinese enterprises. It attempts to investigate the relationships among KM factors including KM strategy, KM enablers (Organizational culture, Organization structure, People, and Technology), KM processes, and organizational performance. The conceptual framework of knowledge management guiding this research is developed from prior research (Alavi, 1997; Davenport, 1999; Lam, 2000; Leonard-Barton, 1995; Nonaka and Takeuchi, 1995; Ramireza nd Dickenson, 2006; Zack, 1999). Previous KM research in the Chinese context has focused on the use of object-perspective measures such as number of created ideas or patents. There appears to be a relative neglect of the relationships between those KM factors. This research focused on exploring the relationships between those KM factors and investigating how they impact on organizational performance in the context of an emerging economy - China. This research adopted the mixed-methods (Creswell, 2003) methodological approach, which involved the use of qualitative and quantitative methods in addressing the research questions raised in this study. The results of this research suggest that organizational culture variables are found to be essential for knowledge creation. In particular, trust is a significant predictor of all knowledge creation processes. The findings of this study confirm that enterprises will be able to obtain strategic benefits of KM through effective knowledge creation processes. The research findings also imply that companies should align their knowledge strategies along with knowledge creation processes. The key to understanding KM in the Chinese context is recognizing the networking nature of the Chinese society which operates on the basis of "Guanxi". In Chinese enterprises, the socialization and externalization elements are remarkably similar to the Japanese situation that Nonaka and Takeuchi (1995) described, as the Chinese are highly networked, hold tacit knowledge within these networks and are prepared to make this knowledge explicit only within the context of these pre-existing relationships. The departmental focus of Chinese enterprises mean that the combination of tacit knowledge is not straightforward, while learning-by-doing is important to sustain their development. The research also indicates that internalization is also problematic in Chinese enterprises because of individuals' fear of admitting mistakes. The implication of the findings for knowledge management and research is discussed

Synthesis of carbon and tungsten based thin films by plasma enhanced chemical vapor deposition

The main objective of this thesis is to find optimum discharge conditions in plasma reactors to realize controlled synthesis of various carbon-based materials with desired properties. Experimental conditions including substrate biasing, substrate pretreatment, gas flow rate, catalyst coating, and the type of carbon source, play important roles in controlling the nucleation and growth of carbon-based materials. In this Ph.D. work, the effects of various processing factors on nucleation and growth of carbon based materials were systematically investigated. The work has led to a better understanding of how each experimental parameter affects the carbon-based materials growth. Optimization of experiment conditions based on this understanding is beneficial for the controlled synthesis of carbon-based materials with desired properties. In addition, the controlled synthesis of tungsten-based nanostructures using a hot filament reactor was studied.The main results presented in this thesis are: (1) Synthesis of well-aligned carbon nanotube or carbon nanocone films with a glow discharge under a negative substrate biasing. The electric field in the plasma sheath above the substrate has been found to play an important role in controlling the alignment and orientation of nanotubes or nanocones. (2) Synthesis of high purity diamond films using solid graphite as the carbon source by graphite etching. The technique provides a route to realizing deposition of high quality diamond films at low substrate temperatures (typically as low as 350 ℃). (3) Successful synthesis of high quality diamond films on aluminum-coated steels using a graphite etching technique. The aluminum interlayer effectively reduces the graphitization which occurs on a steel substrate. (4) Synthesis of nanocrystalline diamond films with smooth surfaces under high gas flow rates with a positive substrate biasing. Both high gas flow rate and positive biasing effectively increase the nucleation density of diamond and therefore reduce the diamond grain size. (5) Synthesis of high purity crystalline tungsten or tungsten oxide nanorod films by optimizing the filament temperature in a hot filament reactor