A 0.5 V tunable complex filter for Bluetooth and Zigbee using OTAs

A 12th-order low voltage tunable differential complex filter for bluetooth and Zigbee applications is proposed in this paper. The filter is based on improved controllable transconductors operating with the ultra-low supply voltage of 0.5 V. Simulation results using a triple-well 0.13 μm CMOS technology verify the filter operation fulfilling all the requirements for the complex filtering stage in bluetooth or Zigbee receivers. The in-band group delay variation is 0.79 μs for bluetooth and 0.46 μs for Zigbee. The image rejection ratio is greater than 71 dB and the achieved in-band spurious free dynamic range is 42 dB.     

Evaluation of visual feedback techniques for virtual grasping with bare hands using Leap Motion and Oculus Rift

Virtual Reality - Bare hand interaction (BHI) allows users to use their hands and fingers to interact with digital content without any attached devices or accessories. For BHI to realize widespread...     

Foldings and grazings of tori in current controlled interleaved boost converters

Interleaved boost converters (IBCs) are used when energy conversion is required at high current levels. Such converter systems may undergo various nonlinear phenomena which can affect their performance adversely. In this paper, we study an IBC and demonstrate the first instability through a Neimark–Sacker bifurcation, resulting in a torus. An analysis based on the calculation of the monodromy matrix reveals that the torus has a rather strange form as the complex Floquet multipliers that became unstable have a real value close to ?1. We show that further variation in a parameter can result in novel nonlinear phenomena where the torus itself folds and grazes a switching manifold, resulting in a ‘wobbling’ of the closed loop that represents the torus in discrete time. Numerical and analytical results validate our work. Copyright © 2013 John Wiley & Sons, Ltd.     

Evaluating the mixing of organic aerosol components using high-resolution aerosol mass spectrometry

According to the pseudo-ideal mixing assumption employed in practically all chemical transport models, organic aerosol components from different sources interact with each other in a single solution, independent of their composition. This critical assumption greatly affects modeled organic aerosol concentrations, but there is little direct experimental evidence to support it. A main experimental challenge is that organic aerosol components from different sources often look similar when analyzed with an aerosol mass spectrometer. We developed a new experimental method to overcome this challenge, using isotopically labeled compounds ((13)C or D) and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). We generated mixtures of secondary organic aerosol (SOA) from isotopically labeled toluene and from unlabeled α-pinene and used the HR-ToF-AMS data to separate these different SOA types. We evaluated their interaction by comparing the aerosol mass yields of toluene and α-pinene when the SOA was formed in these mixtures to their yields when the SOA was formed in isolation. At equilibrium, our results are consistent with pseudo-ideal mixing of anthropogenic and biogenic SOA components from these chemically dissimilar precursors.     

Microbial population, physicochemical quality, and allergenicity of molluscs and shrimp treated with cobalt-60 gamma radiation

Frozen molluscs (squid, octopuses, and cuttlefish) and crustaceans (shrimp) were irradiated using a cobalt-60 gamma source, at different doses, in order to investigate the effects of gamma radiation on their microbial population, organoleptic characteristics, lipid profile, and tropomyosin content. Irradiation of shrimp and squid with either 2.5 or 4.7 kGy reduced mesophilic bacteria contamination to low or nondetectable levels, respectively, whereas irradiation of octopus and cuttlefish with the same doses reduced the bacterial population. Irradiation treatment had no significant (P > 0.05) effect on the total lipid content and the major detected classes of polar and neutral lipids, whereas it significantly (P < 0.05) increased the contents of neutral lipids in octopus mantle and in shrimp muscle and cephalothorax samples. The total fatty acid content and the omega-3: omega-6 fatty acid ration was not affected. A dose-dependent significant (P < 0.05) decrease in the ratio of polyunsaturated fatty acids:saturated fatty acids was observed. With the increase in radiation dose, redness (a) and yellowness (b) values showed a variation, whereas the lightness (L) value was significantly (P < 0.05) decreased in mollusc mantles and shrimp muscle and increased in shrimp cephalothorax. The total of color changes ( delta E) increased (P < 0.05) as the dose increased. Significant (P < 0.05) changes in textural properties were observed with radiation treatment in octopus tentacles and in squid and cuttlefish mantle. The amount of tropomyosin, which is the major mollusc and crustacean allergen in the irradiated organisms, was reduced by gamma radiation, depending on the dose.     

Blast-related fracture patterns: a forensic biomechanical approach

Improved protective measures and medical care has increased the survivability from battlefield injuries. In an attempt to reduce the debilitating consequences of blast injury, understanding and mitigating the effects of explosion on the extremities is key. In this study, forensic biomechanical analyses have been applied to determine mechanisms of injury after the traumatic event. The aims of this study were (i) to determine which effects of the explosion are responsible for combat casualty extremity bone injury in two distinct environments, namely open, free-field (open group), and in vehicle or in cover (enclosed group), and (ii) to determine whether patterns of combat casualty bone injury differed between environments. Medical records of casualties admitted to a military hospital in Afghanistan were reviewed over a six-month period. Explosive injuries have been sub-divided traditionally into primary, secondary and tertiary effects. All radiographs were independently reviewed by a military radiologist, a team of military orthopaedic surgeons and a team of academic biomechanists, in order to determine ‘zones of injury’ (ZoIs), and their related mechanisms. Sixty-two combat casualties with 115 ZoIs were identified. Thirty-four casualties in the open group sustained 56 ZoIs; 28 casualties in the enclosed group sustained 59 ZoIs. There was no statistical difference in mean ZoIs per casualty between groups (p = 0.54). There was a higher proportion of lower limb injuries in the enclosed group compared with the open group (p < 0.05). Of the casualties in the open group, 1 ZoI was owing to the primary effects of blast, 10 owing to a combination of primary and secondary blast effects, 23 owing to secondary blast effects and 24 owing to tertiary blast effects. In contrast, tertiary blast effects predominated in the enclosed group, accounting for 96 per cent of ZoIs. These data clearly demonstrate two distinct injury groups based upon the casualties'' environment. The enclosed environment appears to attenuate the primary and secondary effects of the explosion. However, tertiary blast effects were the predominant mechanism of injury, with severe axial loading to the lower extremity being a characteristic of the fractures seen. The development of future mitigation strategies must focus on reducing all explosion-related injury mechanisms. Integral to this process is an urgent requirement to better understand the behaviour of bone in this unique environment.     

Denting of internally pressurized tubes under lateral loads

The present work examines the structural response of tubular members subjected to lateral quasi-static loading, imposed by wedge-shaped denting devices, in the presence of internal pressure. First, tubes are modeled with shell finite elements, accounting for geometric and material nonlinearities, and the numerical results are in good agreement with available denting test data from internally pressurized pipes. Using the finite element tools, a parametric study is conducted and load-deflection curves are obtained for different levels of pressure, for various wedge shapes and for different types of boundary conditions. It is found that the presence of internal pressure increases significantly the denting force. The effects of yield anisotropy on the denting resistance are also examined. A simplified three-dimensional analytical model is also developed, based on rate-of-energy balance, which yields closed-form expressions for the denting force and the corresponding denting length. The model, introduced elsewhere for non-pressurized tubes, is enhanced to include the pressure effects, accounting for different types of pipe end conditions, as well as the effects of plastic anisotropy. The analytical solution compares very well with finite element results, and illustrates tube denting response in a clear and elegant manner.     

A Public Key Cryptosystem Based on Non-abelian Finite Groups

We present a new approach to designing public-key cryptosystems based on covers and logarithmic signatures of non-abelian finite groups. Initially, we describe a generic version of the system for a large class of groups. We then propose a class of 2-groups and argue heuristically about the system’s security. The system is scalable, and the proposed underlying group, represented as a matrix group, affords significant space and time efficiency. This work was partially supported by a Federal Earmark grant for Research in Secure Telecommunication Networks (2004-05).