1,095 research outputs found
Side-channel Analysis of Subscriber Identity Modules
Subscriber identity modules (SIMs) contain useful forensic data but are often locked with a PIN code that restricts access to this data. If an invalid PIN is entered several times, the card locks and may even destroy its stored data. This presents a challenge to the retrieval of data from the SIM when the PIN is unknown. The field of side-channel analysis (SCA) collects, identifies, and processes information leaked via inadvertent channels. One promising side-channel leakage is that of electromagnetic (EM) emanations; by monitoring the SIM\u27s emissions, it may be possible to determine the correct PIN to unlock the card. This thesis uses EM SCA techniques to attempt to discover the SIM card\u27s PIN. The tested SIM is subjected to simple and differential electromagnetic analysis. No clear data dependency or correlation is apparent. The SIM does reveal information pertaining to its validation routine, but the value of the card\u27s stored PIN does not appear to leak via EM emissions. Two factors contributing to this result are the black-box nature of PIN validation and the hardware and software SCA countermeasures. Further experimentation on SIMs with known operational characteristics is recommended to determine the viability of future SCA attacks on these devices
An investigation into process related fouling of chromatographic supports
This work focuses on the integration of chromatography, specifically ion exchange chromatography (lEC), within a process. Chromatography is commonly used after pretreatment of the crude process stream by at least one processing step designed to remove foulants and competitors which significantly alter the separation and may irreversibly damage the support. Since chromatography represents a considerable proportion of process costs, significant effort is made to reduce the amount of contaminants reaching the chromatographic stage by the use of pre-treatment, incurring a penalty in reduced product yield, increased process time and increased capital/operating costs. The selection of the appropriate pre-treatment is restricted by a lack of knowledge concerning the sensitivity of the chromatography to key contaminants. The development of methods for evaluating the susceptibility to specific foulants is the aim of this work. Initially a test separation of an intracellular enzyme, yeast alcohol dehydrogenase (ADH), was used to determine the changes in chromatographic separations with a variety of process stream compositions. By monitoring the yield and purity of the ADH , the performance was shown to be load and time dependant. This approach was unable to provide a general quantitative analysis: other techniques were used to elicit how the fouling occurred. Frontal analysis was used to relate changes in the chromatographic performance to a decrease in the effective diffusivity of the ion exchange support. The technique was rapid and could be used to define the limit of the feed stream loading. Moment analysis was used to determine a change in the effective diffusivity and the packed column axial dispersion for both functional ion exchange and the base matrices, but required rigorous experiments to obtain consistent results. Results indicated particulate fouling to be a major source of performance change, and that fouling species acted together to produce effects absent when the fouling species was present on it's own. The methods described are generic in application and could provide a basis for improving the integration of chromatography into processes
Topological Defects in Twisted Bundles of Two-Dimensionally Ordered Filaments
Twisted assemblies of filaments in ropes, cables and bundles are essential
structural elements in wide use in macroscopic materials as well as within the
cells and tissues of living organisms. We develop the unique, non-linear
elastic properties of twisted filament bundles that derive from generic
properties of two-dimensional line-ordered materials. Continuum elasticity
reveals a formal equivalence between the elastic stresses induced by bundle
twist and those induced by the positive curvature in thin, elastic sheets.
These geometrically-induced stresses can be screened by 5-fold disclination
defects in lattice packing, and we predict a discrete spectrum elastic energy
groundstates associated with integer numbers of disclinations in cylindrical
bundles. Finally, we show that elastic-energy groundstates are extremely
sensitive to defect position in the cross-section, with off-center
disclinations driving the entire bundle to buckle, adopting globally writhing
configurations.Comment: 4.1 pages; 3 figure
From calculators to 21st century computing: successes and opportunities in digital technology for textiles
U radu se daje pregled primjena digitalne tehnologije u tekstilnim industrijama od sredine 20. stoljeÄa do 21. stoljeÄa. Na poÄetku je opisan napredak alata koji se koriste. Nakon toga se u poglavljima porikazuje estetski dizajn, strojevi i postupci, te uporaba digitalne tehnologije u veleprodaji i maloprodaji. Postoje velike moguÄnosti u podruÄju tehniÄkog oblikovanja i virtualnih pogona, ali programska rjeÅ”enja proiziÅ”la iz znanstvenih istraživanja joÅ” nisu dospjela do industrije.The paper reviews the applications of digital technology to the textile industries from the mid-20th century to the 21st century. The advances in the available tools are first described. Sections then cover aesthetic design, machines and operations, and commercial and retail, all of which are in general use. For engineering design and the āvirtual catwalkā, there are great opportunities but software from academic research has hardly been taken up by industry
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