Stereophonic acoustic echo cancellation employing selective-tap adaptive algorithms

Published versio

New product development in an emerging economy: analysing the role of supplier involvement practices by using Bayesian Markov chain Monte Carlo technique

The research question is whether the positive relationship found between supplier involvement practices and new product development performances in developed economies also holds in emerging economies. The role of supplier involvement practices in new product development performance is yet to be substantially investigated in the emerging economies (other than China). This premise was examined by distributing a survey instrument (Jayaram’s (2008) published survey instrument that has been utilised in developed economies) to Malaysian manufacturing companies. To gauge the relationship between the supplier involvement practices and new product development (NPD) project performance of 146 companies, structural equation modelling was adopted. Our findings prove that supplier involvement practices have a significant positive impact on NPD project performance in an emerging economy with respect to quality objectives, design objectives, cost objectives, and “time-to-market” objectives. Further analysis using the Bayesian Markov Chain Monte Carlo algorithm, yielding a more credible and feasible differentiation, confirmed these results (even in the case of an emerging economy) and indicated that these practices have a 28% impact on variance of NPD project performance. This considerable effect implies that supplier involvement is a must have, although further research is needed to identify the contingencies for its practices

The converse of the passivity and small-gain theorems for input-output maps

We prove the following converse of the passivity theorem. Consider a causal system given by a sum of a linear time-invariant and a passive linear time-varying input-output map. Then, in order to guarantee stability (in the sense of finite L2-gain) of the feedback interconnection of the system with an arbitrary nonlinear output strictly passive system, the given system must itself be output strictly passive. The proof is based on the S-procedure lossless theorem. We discuss the importance of this result for the control of systems interacting with an output strictly passive, but otherwise completely unknown, environment. Similarly, we prove the necessity of the small-gain condition for closed-loop stability of certain time-varying systems, extending the well-known necessity result in linear robust control.Comment: 15 pages, 3 figure

Stabilization of Cascaded Two-Port Networked Systems Against Nonlinear Perturbations

A networked control system (NCS) consisting of cascaded two-port communication channels between the plant and controller is modeled and analyzed. Towards this end, the robust stability of a standard closed-loop system in the presence of conelike perturbations on the system graphs is investigated. The underlying geometric insights are then exploited to analyze the two-port NCS. It is shown that the robust stability of the two-port NCS can be guaranteed when the nonlinear uncertainties in the transmission matrices are sufficiently small in norm. The stability condition, given in the form of "arcsin" of the uncertainty bounds, is both necessary and sufficient.Comment: 8 pages, in preparation for journal submissio

Convergence of cytokines and hypoxia on colorectal cancer angiogenesis

Over-expression of Epidermal Growth Factor (EGF) and hypoxia are features of colorectal cancer (CRC). Such observations have helped develop novel therapies such as cetuximab, a recombinant monoclonal EGF receptor antibody antagonist. Recent studies uncovered a pro-angiogenic role for EGF but it is unclear whether this is mediated by Vascular Endothelial Growth Factor (VEGF) in CRC. Moreover, it is unknown whether hypoxia synergises with EGF to accentuate their individual pro-angiogenic effects. The aim of the study was to investigate the angiogenic effect promoted by EGF in combination with hypoxia in CRC. CRC cell lines Colo 201 and Caco-2 were stimulated with EGF and/or exposed to 1% O2 or dimethyloxalylglycine (DMOG), a hypoxia-mimetic. Gene and protein expression of hypoxia inducible factor (HIF)-1α, HIF-2α and VEGF were assessed. Gene signatures of CRC cells following EGF, hypoxia and DMOG stimulations were assessed by angiogenesis PCR arrays. The functional significance was assessed by human umbilical vein endothelial cell (HUVEC) migration assay co-cultured with Caco-2. HIF-1α and VEGF protein were upregulated in Caco-2 with EGF and DMOG stimulation. However, Colo 201 demonstrated an increase in VEGF mRNA and protein only under hypoxia but not with EGF. The discrepancy in responses to EGF was attributed to differences in ERK kinase signalling between the two cell types. PCR angiogenesis arrays also identified angiopoietin-like 4 and ephrin A3 as novel genes which were upregulated by HIF overexpression, and stabilin-1, a gene specifically downregulated by EGFR-activation. Functional relevance was confirmed by HUVEC migration assay, demonstrating similar numbers of migrated HUVEC cell numbers in co-cultures with Caco-2 pre-stimulated with EGF and DMOG compared to unstimulated controls. In conclusion, EGF receptor activation plays a role in CRC angiogenesis by increasing VEGF and HIF-1α protein expression, although such effect is dependent upon functional ERK MAPK signalling. However, hypoxia and DMOG consistently exerted an over-riding stimulus in significantly promoting expression of angiogenic mediators to drive endothelial migration and angiogenesis in CRC

The Contemporary Malaysian Fantastic Film: Imagining an Alternative Modernity

The thesis posits that contemporary Malaysian fantastic films possess critical characteristics: they offer an alternative version of an imagined community and undermine the status quo. These films deploy elements of fantasy to negotiate the dominant notions of cultural and national identity in Malaysia. However, my study notes that the degree of resistance in such films is contingent on how well the filmmakers navigate the censorship guidelines, and negotiate with the authorities, and highlight the ongoing tension between artistic freedom and state control in film production. Most filmmakers of the fantastic genre do not produce films that are explicitly critical as such. As I will demonstrate, they need to navigate the productive dimension of censorship. My key aim is to overcome the limitation of Malaysian cinema scholarship that focuses exclusively on censorship as prohibitive. This thesis aims to broaden the scope of research on Malaysian cinema by examining the role of censorship in shaping the emergence and development of the fantastic film as a genre. Rather than simply viewing censorship as a hindrance to creative expression, this thesis argues that censorship can also be productive and lead to new forms of artistic expression. Alongside textual analysis, I interview filmmakers and study the history and recent change in censorship practices to gain a deeper understanding of current fantastic film practices in Malaysia. By doing so, the study hopes to contribute to a more nuanced understanding of how Malaysian national and ethnic identity is constructed in film. My thesis proposes a definition of the fantastic film that identifies several stylistic features constructing an alternative national identity, thereby promoting diverse notions of belonging. The Malaysian fantastic films are intertextual. They deploy Computer Graphic Imagery (CGI), and their representation of religious and racial identities explore interaction between official and unofficial definitions of nationhood. In 2003 the Malaysian censorship policy was revised, thus, allowing the production of fantastic films which had been banned for decades. This shift came with new censorship guidelines that aimed to impose control influenced by the rise of Islamisation and the emphasis on Malay paramountcy. In times of political and ideological crisis the stylistic strategies invoked in these films become crucial in negotiating with the authority and offering relief when other institutions fail. This thesis argues that fantastic films have the tendency to perform criticism with such films serving to present an alternative version of an imagined community and questioning the status quo. The thesis delineates several types of Malaysian fantastic films in terms of stylistic features that construct an alternative national identity and promote different notions of belonging, which are often facilitated by religious influences, racial identity and technological advancement in presenting the conflict of interests between the public and private definitions of nationhood

Robust stability conditions for feedback interconnections of distributed-parameter negative imaginary systems

Sufficient and necessary conditions for the stability of positive feedback interconnections of negative imaginary systems are derived via an integral quadratic constraint (IQC) approach. The IQC framework accommodates distributed-parameter systems with irrational transfer function representations, while generalising existing results in the literature and allowing exploitation of flexibility at zero and infinite frequencies to reduce conservatism in the analysis. The main results manifest the important property that the negative imaginariness of systems gives rise to a certain form of IQCs on positive frequencies that are bounded away from zero and infinity. Two additional sets of IQCs on the DC and instantaneous gains of the systems are shown to be sufficient and necessary for closed-loop stability along a homotopy of systems.Comment: Submitted to Automatica, A preliminary version of this paper appeared in the Proceedings of the 2015 European Control Conferenc