Algebraic analysis of Trivium-like ciphers

Trivium is a bit-based stream cipher in the final portfolio of the eSTREAM project. In this paper, we apply the approach of Berbain et al. to Trivium-like ciphers and perform new algebraic analyses on them, namely Trivium and its reduced versions: Trivium-N, Bivium-A and Bivium-B. In doing so, we answer an open question in the literature. We demonstrate a new algebraic attack on Bivium-A. This attack requires less time and memory than previous techniques which use the F4 algorithm to recover Bivium-A's initial state. Though our attacks on Bivium-B, Trivium and Trivium-N are worse than exhaustive keysearch, the systems of equations which are constructed are smaller and less complex compared to previous algebraic analysis. Factors which can affect the complexity of our attack on Trivium-like ciphers are discussed in detail

Loss of coordination in competitive supply chains

Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 161-163).The loss of coordination in supply chains quantifies the inefficiency (i.e. the loss of total profit) due to the presence of competition in the supply chain. In this thesis, we discuss four models: one model with multiple retailers facing the multinomial logit demand, and three supply chain configurations with one supplier and multiple retailers in a i) quantity competition among retailers with substitute products, ii) price competition among retailers with substitute products, and iii) quantity competition among retailers with complement products, producing differentiated products under an affine demand function. As a special case, we also consider the symmetric setting in the four models where all retailers encounter identical demand, marginal costs, quality dierences, and in the multinomial logit demand case, when there are identical variances in the consumers' utility functions. The main contribution in this thesis lies in the precise quantification of the loss of profit due to lack of coordination, through analytical lower bounds. We provide bounds in terms of the eigenvalues of the demand sensitivity matrix, or the demand sensitivities. For the multinomial logit demand model, the lower bounds are in terms of the number of retailers and the predictability of consumer behaviour. We use simulations to provide further insights on the loss of coordination and tightness of the bounds. We find that a supply chain with retailers operating under Bertrand competition offering substitute products is the most ecient with an average profit loss of less than 15%. We also nd that competitive supply chains can be coordinated when offering substitute products.(cont.) This occurs under the symmetric setting when there is a 'reasonable' number of Cournot retailers under intense competition, or when demand is 'more' inelastic in a Bertrand competition setting. As an example, in the presence of six Cournot retailers under intense competition, the profit loss is 2.04%, and when demand is perfectly inelastic in a Bertrand competition, the supply chain is perfectly coordinated with profit loss of 0%. For the multinomial logit demand case, we nd that higher predictability of consumer behaviour (i.e, when consumers' choices are more deterministic) increases profits both under coordination and under competition, and a larger number of retailers decreases profits under competition, but 3 increases profits under coordination. The net result is that efficiency 'deteriorates' when the number of competitive retailers and predictability of consumer behaviour increases.by Koon Soon Teo.S.M

Magnetic superlens-enhanced inductive coupling for wireless power transfer

We investigate numerically the use of a negative-permeability "perfect lens" for enhancing wireless power transfer between two current carrying coils. The negative permeability slab serves to focus the flux generated in the source coil to the receiver coil, thereby increasing the mutual inductive coupling between the coils. The numerical model is compared with an analytical theory that treats the coils as point dipoles separated by an infinite planar layer of magnetic material [Urzhumov et al., Phys. Rev. B, 19, 8312 (2011)]. In the limit of vanishingly small radius of the coils, and large width of the metamaterial slab, the numerical simulations are in excellent agreement with the analytical model. Both the idealized analytical and realistic numerical models predict similar trends with respect to metamaterial loss and anisotropy. Applying the numerical models, we further analyze the impact of finite coil size and finite width of the slab. We find that, even for these less idealized geometries, the presence of the magnetic slab greatly enhances the coupling between the two coils, including cases where significant loss is present in the slab. We therefore conclude that the integration of a metamaterial slab into a wireless power transfer system holds promise for increasing the overall system performance

Banking Strategy COmpetitive Landscape for China Banking Industry

China is one of the most exciting countries for global bankers, the large population and strong economic growth signify amber of business opportunities, but more importantly, it’s increasingly influence on the world economy means no one can neglect the market potential. Given its huge market potential, global bankers, have been constantly seeking market entry and development opportunities in the China’s banking sector. Nonetheless, banking industry is highly regulated, with their product and service offerings, markets, and operations heavily controlled by each country’s regulators. The restriction is particularly severe in China under its socialism political structure. Hence, how global banker, in this case, Standard Chartered Bank (SCB), differentiates itself from the rest of market players, in such a restrictive environment, represent the foremost challenge. The study looks at the competitive forces that govern the banking industry and the strategic interactions between the market players. Opportunities and threats are highlighted in tandem with the analysis of the roles of “complementors” and government, which then serve as an input for SCB’s strategic propositioning in China. Four trends emerge strongly from the study: - The banking sector is experiencing structural change towards more efficient and competitive environment, which, to some extent, put foreign bank at greater disadvantages. - Banking sector lacks the differentiation, but innovation in product features alone, may not work. Service is the best differentiators. - Building up solid government relations is the key factor in doing business in China. - Localisation and adaptation are important, as cultures are always the key barrier. However, the industry is undergoing rapid evolution and SCB has to continually scan the environment, to be on top of every opportunities and threats. More importantly, for any trends that emerge from the banking study, its implications need to be considered within the global strategy framework, as any decisions derived therein, will have spill over effect onto its other market, hence global profitability

Methods for increasing model accuracy and simulation time scales of biological processes with molecular dynamics

This dissertation presents three research projects on novel methods in computational bio- physics. Each of these projects introduces methodologies to extend the capabilities of molecular dynamics simulations in one way or another. In the first chapter, molecular dynamics simulations and the central role they play in the field of structural biology is introduced to give the reader some background on the common basis of the projects. The second chapter describes the first of these projects, where the molecular dynamics flexible fitting method for refining molecular structures of macromolecules using experimental electron density data is extended to be able to handle high-resolution density data, which are becoming increasingly commonplace. The third chapter focuses on adaptive multilevel splitting, a replica-based sampling technique that was employed in molecular dynamics simulations to measure the rate of drug molecule dissociation, a process that occurs on the order of milliseconds and above, which is out of the reach of typical molecular dynamics simulations. In the final chapter, a kinetic model of diffusion is introduced. This model allows simulation of the diffusion of small molecules in arbitrary potentials, for example, those that characterize the space around and within a membrane protein channel. The adaptive discretization scheme allows simulations between the micro- to millisecond time scales, which are typical of diffusive processes. This collection of projects is a snapshot of the diversity and versatility of current problems in structural biology that can be addressed by molecular dynamics simulations. I hope to instill in the reader a sense of how method development in molecular dynamics will expand the contributions of the field to both scientific and practical pursuits in biology

Radar imaging for moving targets

Interest in radar imaging has been growing for the past decades because of its long-range sensing capabilities. Its continued utility and applications in wide-ranging areas is fundamentally dependant on the ability to produce high-quality, artifact-free imagery. The use of radar to identify and image moving targets remains of great interest for both commercial and military usage. However, when imaging moving targets, there will be issues of incorrect positioning or streaking, as the unknown target velocity gives rise to image artifacts. Many techniques have been developed to handle moving objects; however, these techniques make use of the so-called start-stop approximation in which target motion is assumed to be momentarily stationary while it is being interrogated by a radar pulse. A new linearized imaging theory that combines spatial, temporal and spectral aspects of scattered waves has been developed. This thesis considers the performance of these techniques compared to existing imaging schemes. It is shown that the new imaging scheme provides better localization, and is translation invariant in phase-space. It is also shown that the imaging scheme is dependent on the aperture geometry.http://archive.org/details/radarimagingform109454681Republic of Singapore Army author.Approved for public release; distribution is unlimited

Banking Strategy Demography - Future Population Trend: Implication for Banking

The world is going through a major shift in demographic structure that will affect the economies and global markets in a major way over the next few decades. While extensive research has been done on the macro-economic implications of demographic changes, very little research has been conducted on the demographic challenges at an industry level or for firms and on how these firms should react. The banking sector, in particular has received little attention. The project is initiated by the Global Research team of Standard Chartered Bank (SCB). The objective of the project is to study and highlight demographic trends and thereby understand its implications on the banking industry and the strategy of SCB. The study intends to answer the following questions: - What are the key demographic trends facing the world today and in the future over a 20 year time horizon - How will these trends change the structure of the global economy and the banking environment - In view of the changing global market dynamics, what are the indicative opportunities and risks for the future? Where do the greatest opportunities lie and what is the relative intensity (attractiveness rankings) - What implications would these changes, risks and opportunities have on Standard Chartered Bank and what are the strategic options available (product market opportunities) to prepare for the changing dynamics 3 trends have come out strongly as the outcome to the study: - We are already experiencing a structural change of the global economy where the power and opportunities are shifting from the west to east due to an ageing western population and the “demographic dividend” being enjoyed by the Eastern Countries - India and China have been at the top of every list highlighting opportunities. However, the opportunities are not concentrated in Asia alone with the emergence of VISTA and the rise of new emerging markets such as Mexico, Peru, Colombia in Latin America; Saudi Arabia, Iran in the Middle East and Angola, Egypt in Africa. - The rise of the emerging market middle class, redefining the rules of the market The study has been concluded with detailed recommendations that have been arrived at through a combined implication assessment of demographic trends, economic forecasts, industry trends and the competitive landscape

A Direct Assessment of “Obesogenic” Built Environments: Challenges and Recommendations

This paper outlines the challenges faced during direct built environment (BE) assessments of 42 Canadian communities of various income and urbanization levels. In addition, we recommend options for overcoming such challenges during BE community assessments. Direct BE assessments were performed utilizing two distinct audit methods: (1) modified version of Irvine-Minnesota Inventory in which a paper version of an audit tool was used to assess BE features and (2) a Physical Activity and Nutrition Features audit tool, where the presence and positions of all environmental features of interest were recorded using a Global-Positioning-System (GPS) unit. This paper responds to the call for the need of creators and users of environmental audit tools to share experiences regarding the usability of tools for BE assessments. The outlined BE assessment challenges plus recommendations for overcoming them can help improve and refine the existing audit tools and aid researchers in future assessments of the BE