Multi-device anonymous authentication

Recently, a few pragmatic and privacy protecting systems for authentication in multiple systems have been designed. The most prominent examples include Pseudonymous Signatures for German personal identity cards and Anonymous Attestation. The main properties are that a user can authenticate himself with a single private key (stored on a smart card), but nevertheless the user’s IDs in different systems are unlinkable. We develop a solution which enables a user to achieve the above-mentioned goals while using more than one personal device, each holding a single secret key, but different for each device. Our solution is privacy preserving: it will remain hidden for the service system which device is used. Nevertheless, if a device gets stolen, lost or compromised, the user can revoke it (leaving his other devices intact). In particular, in this way we create a strong authentication framework for cloud users, where the cloud does not learn indirectly personal data. Our solution is based on a novel cryptographic primitive, called Pseudonymous Public Key Group Signature.

     

A statistical filtering method for denoising of micro-force measurements

Precise measurement of mechanical forces is crucial to efficient micro-manufacturing. The quality of such measurements depends heavily on the properties of the noise inevitably accompanying every measurement process. In the micro-range, the signal-to-noise ratio tends to be very low, and the noise dynamic varies for different frequencies. In result, common denoising methods that assume white noise perform poorly in this setting. In this paper, a novel, easily implementable denoising method based on a local statistic of the measured data’s spectrum is proposed. By testing it on a representative dataset, it is shown that the proposed method is robust and stable. Particularly, it allows for an efficient retrieval of the force signal encountered in micro-milling processes.     

Periodic autoregressive model identification using genetic algorithms

Periodic autoregressive (PAR) models extend the classical autoregressive models by allowing the parameters to vary with seasons. Selecting PAR time‐series models can be computationally expensive, and the results are not always satisfactory. In this article, we propose a new automatic procedure to the model selection problem by using the genetic algorithm. The Bayesian information criterion is used as a tool to identify the order of the PAR model. The success of the proposed procedure is illustrated in a small simulation study, and an application with monthly data is presented.     

Communication Requirements and Interconnect Optimization for High-End Scientific Applications

The path toward realizing next-generation petascale and exascale computing is increasingly dependent on building supercomputers with unprecedented numbers of processors. To prevent the interconnect from dominating the overall cost of these ultrascale systems, there is a critical need for scalable interconnects that capture the communication requirements of ultrascale applications. It is, therefore, essential to understand high-end application communication characteristics across a broad spectrum of computational methods, and utilize that insight to tailor interconnect designs to the specific requirements of the underlying codes. This work makes several unique contributions toward attaining that goal. First, we conduct one of the broadest studies to date of high-end application communication requirements, whose computational methods include: finite difference, lattice Boltzmann, particle-in-cell, sparse linear algebra, particle-mesh ewald, and FFT-based solvers. Using derived communication characteristics, we next present the fit-tree approach for designing network infrastructure that is tailored to application requirements. The fit-tree minimizes the component count of an interconnect without impacting application performance compared to a fully connected network. Finally, we propose a methodology for reconfigurable networks to implement fit-tree solutions. Our Hybrid Flexibly Assignable Switch Topology (HFAST) infrastructure, uses both passive (circuit) and active (packet) commodity switch components to dynamically reconfigure interconnects to suit the topological requirements of scientific applications. Overall, our exploration points to several promising directions for practically addressing the interconnect requirements of future ultrascale systems.     

The replacement of chromate by molybdate in phosphoric acid-based etch solutions for aluminium alloys

Corrosion inhibition of aluminium alloys in the acidic solutions is important in the aluminium finishing industry (stripping solutions for anodic films). Sodium molybdate is a potential replacement for chromate-containing species used in the stripping solutions. It was tested as the corrosion inhibitor of 2024 aluminium alloy in orthophosphoric acid solutions. A corrosion rate of the alloy as a function of an initial concentration of sodium molybdate and temperature was determined by using gravimetric and gasometric methods. The corrosion rate was significantly lower in the solutions containing over 5?mM of sodium molybdate when compared to the uninhibited solution. The inhibition efficiency decreased with the increase of the temperature for the constant concentration of sodium molybdate. Sodium molybdate reduced the corrosion of the alloy by adsorption as well as formation of insoluble corrosion products on the alloy.     

Some thoughts on bondability and strength of gold wire bonding

The bonding mechanisms of gold, to give the desired strength of wire bonding, still require detailed investigation, including establishing adequate and reliable testing procedures. The current practices for analysing the mechanisms of wire bonding are inadequate and do not provide a comprehensive picture. This is because the focus of the tests is not clear, which causes variation in the results obtained, changing the conclusions about the responsible mechanism. Furthermore, as the size of Au wire bonds decreases, the mechanism responsible for thermosonic Au wire bonding may change. This paper provides a comprehensive analysis of the current and possible future methods for elaborating the bonding mechanism and strength of thermosonic Au wire bonds. We discuss the testing methods, their limitations and advantages, and suggest ways in which they can be improved.     

Ultrathin films of co-sputtered CrZrx alloys on polymeric substrates

This experimental study combines the research topics of ultrathin films on polymeric substrates with binary transition metal alloys. Chrome zirconium (CrZr_x), ca. 60 nm, was co-sputtered onto pre-coated polymeric substrates having a glass transition temperature below 150 °C. As a consequence of this, the ultrathin films are deposited under vacuum at temperatures below 100 °C, over time frames of only 1 to 2 min. For the ultrathin CrZr_x alloy films we report the coexistence of the body centred cubic and Ω-hexagonally close packed phase within a narrow Zr concentration range. The influence of this atomic structure, in combination with the electron structure of the ultrathin CrZr_x film, on the optical and mechanical performance is investigated. Results show the change in structure with elemental composition correlates with variations in the molecular orbital filling of the atoms, thus yielding changes in the optical reflectivity and the resistance to abrasion.     

Infrared transmittance model for pyrometric monitoring of surface quality of thin diamond films

The thickness and surface roughness of thin diamond films grown on quartz substrates are studied in the paper using a model of changes in the infrared transmission ratio associated with multiple constructive interference within a thin crystal film. On the other hand, the model is referred to periodic variations of the apparent temperature of the substrate measured by the two-color pyrometer. Obtained results are then compared with those of other similar studies, and the AFM measurements. Some discrepancy between the results from infrared and AFM data is explained in terms of optical absorption of the crystal, which is neglected in the transmittance model.     

Thermal characterization of screen printed conductive pastes for RFID antennas

Thermal resistance is an essential aspect of electronic circuits designing. It leads to unexpected changes in electronic components during their work. In this study, new materials for screen printed RFID tag's antennas were characterized in terms of their resistance to thermal exposure. Polymer materials containing silver flakes, silver nanopowder, carbon nanotubes or conductive polymer PEDOT:PSS were elaborated and used for antenna printing on flexible materials. In order to verify their long term susceptibility to damages caused by the changing environmental conditions, the temperature cycling test was used in three different temperature ranges: +65 °C, −12 °C, −40 °C/+85 °C (3 h in each temp., dwell time 1 h). The highest durability to thermal exposure exhibited the paste with carbon nanotubes dispersed in poly(methyl methacrylate) PMMA and the lowest one – the paste with conductive polymer PEDOT:PSS.     

An integrated approach to the optimization of in-plant wastewater interception with mass and property constraints

This article addresses the problem of in-plant pollution prevention for processes with multiple streams, containing pollutants and environmentally undesirable properties through mass exchange networks (MEN). In-plant interception is used to adjust the concentrations and properties of the wastewater streams. A pinch-based disjunctive-optimization approach is adopted. The determination of the pinch point (being the most constrained thermodynamic and practical operating condition) is critical for determination of optimum design conditions. The selection of the appropriate mass separating agent(s) (MSAs) is based on thermodynamic and economic considerations. A screening procedure modeled through mathematical programming is developed with disjunctive constraints to screen alternatives and invoke the proper models when a certain technology is to be utilized. A case study is solved to illustrate the proposed approach.