Dependability issues in visual–haptic interfaces

Dependability of a system is commonly referred to its reliability, its availability and its maintenability (RAM), but when this concept is applied to user interfaces there is no common agreement on what aspects of user–system interaction are related to a satisfactory RAM level for the whole system. In particular, when dealing with haptic systems, interface dependability may become a crucial issue in medical and in military domains when life-critical systems are to be manipulated or where costly remote control operations are to be performed, like in industrial processes control or in aerospace/automotive engineering and manufacturing. This paper discusses the role of dependability in haptic user interfaces, aiming to the definition of a framework for the assessment of the usability and dependability properties of haptic systems and their possible correlations. The research is based on the analysis of a visual–haptic-based simulator targeted to maintenance activity training for aerospace industry which is taken as a case study. As a result, we propose a novel framework able to collect and then process relevant interaction data during the execution of haptic tasks, enabling to analyze dependability vs. usability correlations.     

Asymptotically Optimal Solutions for Small World Graphs

We consider the problem of determining constructions with an asymptotically optimal oblivious diameter in small world graphs under the Kleinberg’s model. In particular, we give the first general lower bound holding for any monotone distance distribution, that is induced by a monotone generating function. Namely, we prove that the expected oblivious diameter is Ω(log ² n) even on a path of n nodes. We then focus on deterministic constructions and after showing that the problem of minimizing the oblivious diameter is generally intractable, we give asymptotically optimal solutions, that is with a logarithmic oblivious diameter, for paths, trees and Cartesian products of graphs, including d-dimensional grids for any fixed value of d. The research was partially funded by the European project COST Action 293, “Graphs and Algorithms in Communication Networks” (GRAAL).     

Post-transplant proteinuria associated with everolimus: Definition of main features with proteomics

Little is known on both the composition and mechanism(s) of proteinuria associated with the use of mTOR inhibitors, in particular of Everolimus (E). We characterized urinary proteins utilizing an integrated proteomics approach (quantitative essays, 2‐DE, MALDI‐TOF, Western blot) in 48 renal transplant recipients who were alternatively treated with E (n = 31) or with enteric coated mycophenolic acid (EC‐MPA) (n = 17). Twelve E patients (39%) developed high (>3 g/day) or intermediate proteinuria (1–3 g) compared to four (23%) of the EC‐MPA group. Urinary proteins (p<0.001), β2 microglobulin (p<0.001) and α1microglobulin (p<0.025) were higher in E than in EC‐MPA, appeared more rapidly and were inversely correlated with the day of treatment. Proteomics showed a marked increase of all urinary components in E and EC‐MPA patients, major changes involving typical components of glomerular damage (albumin, α1‐Zn glycoprotein, α2HS glycoprotein, leucin‐richα2‐glycoprotein) and specific bio‐markers for E (clusters of α1‐antitrypsin fragments and monoclonal λ chains). Finally, inter‐α‐trypsin‐inhibitor heavy chain H4 precursor was decreased in E and EC‐MPA urine compared to normal urine. In conclusion, E induced massive and generalized proteinuria of mixed glomerular and tubular origin that was correlated with the start of treatment and reached a nephrotic range in few cases. Specific urinary markers reflect renal alterations related to the transplant or specific alterations associated with the drug.     

A novel technique for the direct determination of multimode equivalent circuit models for substrate integrated waveguide discontinuities

A novel technique is presented for the automatic, self‐consistent and direct determination of wide‐band lumped‐element equivalent circuit models of substrate integrated waveguide discontinuities. This technique is based on the full‐wave analysis of substrate integrated waveguide components by using the Boundary Integral‐Resonant Mode Expansion method, which provides a generalized admittance matrix of the components in the form of a pole expansion in the frequency domain. This expression of the admittance matrix permits to directly identify the topology of a multimodal equivalent circuit and the values of its lumped elements, thus avoiding any initial guess or fitting procedure. The basic theory of the full‐wave analysis method and the procedure for determining the equivalent circuit model are reported. The features of the proposed technique are detailed through the modeling of an iris‐like discontinuity. Moreover, this technique is validated by modeling substrate integrated waveguide filters, whose frequency response is compared with numerical and experimental results. The proposed method can be adopted to obtain libraries of parametric models of substrate integrated waveguide discontinuities, which can be included in computer aided design tools. The multimodal parametric model of an iris‐like discontinuity is presented and discussed. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

A self-adaptive multi-engine solver for quantified Boolean formulas

In this paper we study the problem of engineering a robust solver for quantified Boolean formulas (QBFs), i.e., a tool that can efficiently solve formulas across different problem domains without the need for domain-specific tuning. The paper presents two main empirical results along this line of research. Our first result is the development of a multi-engine solver, i.e., a tool that selects among its reasoning engines the one which is more likely to yield optimal results. In particular, we show that syntactic QBF features can be correlated to the performances of existing QBF engines across a variety of domains. We also show how a multi-engine solver can be obtained by carefully picking state-of-the-art QBF solvers as basic engines, and by harnessing inductive reasoning techniques to learn engine-selection policies. Our second result is the improvement of our multi-engine solver with the capability of updating the learned policies when they fail to give good predictions. In this way the solver becomes also self-adaptive, i.e., able to adjust its internal models when the usage scenario changes substantially. The rewarding results obtained in our experiments show that our solver AQME—Adaptive QBF Multi-Engine—can be more robust and efficient than state-of-the-art single-engine solvers, even when it is confronted with previously uncharted formulas and competitors.     

Analysis of laminar-to-turbulent transition for isothermal gas flows in microchannels

In this work the laminar-to-turbulent transition in microchannels of circular cross-section is studied experimentally. In order to single out the effects of relative roughness, compressibility and channel length-to-diameter ratio on the Reynolds number at which transition occurs, experimental runs have been carried out on circular microchannels in fused silica—smooth for all purposes—and in stainless steel (which possess a high surface roughness), with a diameter between 125 and 180 μm and a length of 5–50 cm through which nitrogen flows. For each tube the friction factor has been computed. The values of the critical Reynolds number have been determined plotting the Poiseuille number (i.e., the product of the friction factor, f, times the Reynols number, Re) as a function of the average Mach number between inlet and outlet. The transitional regime was found to start no earlier than at values of the Reynolds number around 1,800–2,000. It has been observed that surface roughness has no effect on the hydraulic resistance in the laminar region for a relative roughness lower than 4.4%, and that friction factor obeys the Poiseuille law, if it is correctly computed taking compressibility into account. It is found that recent correlations for the prediction of the critical Reynolds number in microchannels that link the relative roughness of the microtubes to the critical Reynolds number do not agree with the present results.     

Comments on “Adaptive variable structure set-point control ofunderactuated robots”

In this note, we point out the fallacies of above mentioned paper by Su et al. (ibid. vol.44 (1999)) concerning the stabilization of underactuated robots     

Practical network security: experiences with ntop

As networks become large and heterogeneous, network administrators need efficient tools for monitoring network activities and enforcing global security. In open environments such as universities and research organisations, it is rather difficult to prevent access to core network resources without restricting users’ freedom.Ntop is an open-source web-based traffic measurement and monitoring application written by the authors and widely available on the Internet. This paper shows how ntop can also be effectively used for network security as it is able to identify potential intruders and security flaws, as well as discover misconfigured or faulty applications that generate suspicious traffic.     

Improved In Situ Characterization of Electrochemical Interfaces Using Metasurface-Driven Surface-Enhanced IR Absorption Spectroscopy

Electrocatalysis plays a crucial role in realizing the transition toward a zero-carbon future, driving research directions from green hydrogen generation to carbon dioxide reduction. Surface-enhanced infrared absorption spectroscopy (SEIRAS) is a suitable method for investigating electrocatalytic processes because it can monitor with chemical specificity the mechanisms of the reactions. However, it remains difficult to detect many relevant aspects of electrochemical reactions such as short-lived intermediates. Herein, an integrated nanophotonic-electrochemical SEIRAS platform is developed and experimentally realized for the in situ investigation of molecular signal traces emerging during electrochemical experiments. A platinum nano-slot metasurface featuring strongly enhanced electromagnetic near fields is implemented and spectrally targets the weak vibrational mode of the adsorbed carbon monoxide at ≈2033 cm⁻¹. The metasurface-driven resonances can be tuned over a broad range in the mid-infrared spectrum and provide high molecular sensitivity. Compared to conventional unstructured platinum films, this nanophotonic-electrochemical platform delivers a 27-fold improvement of the experimentally detected characteristic absorption signals, enabling the detection of new species with weak signals, fast conversions, or low surface concentrations. By providing a deeper understanding of catalytic reactions, the nanophotonic-electrochemical platform is anticipated to open exciting perspectives for electrochemical SEIRAS, surface-enhanced Raman spectroscopy, and other fields of chemistry such as photoelectrocatalysis.