Inverse analysis procedure to determine flow stress and friction data for finite element modeling of machining

This paper describes an inverse procedure to determine the constitutive constants and the friction conditions in the machining processes using Finite Elements (FE) simulations. In general, the FE modeling of machining processes is an effective tool to analyze the materials machinability under different cutting conditions. However, the use of reliable rheological and friction models represents the basis of a correct numerical investigation. The presented inverse procedure was based on the numerical results obtained using a commercial FE code and was developed considering a specific optimization problem, in which the objective functions that have to be minimized is the experimental/numerical error. This problem was performed by a routine developed in a commercial optimization software. In order to verify the goodness and the robustness of the methodology, it was applied on a Super Duplex Stainless Steel (SDSS) and on an Austenitic Stainless Steel (AUSS) orthogonal machining processes. This work, then, was focused on the identification of the Johnson-Cook (JC) coefficients (A,B,C, n and m) and on the calibration of a Coulomb friction model, in the specific cases of the SAF2507 SDSS and of an AISI 316 Based AUSS Alloy (AISI 316 ASBA). The identification phases were performed considering forces and temperatures experimental data, collected in two specific experimental tasks in which different orthogonal cutting tests were carried out under different cutting parameters conditions.     

The P2X7R-NLRP3 and AIM2 Inflammasome Platforms Mark the Complexity/Severity of Viral or Metabolic Liver Damage

P2X7R-NLRP3 and AIM2 inflammasomes activate caspase-1 and the release of cytokines involved in viral-related liver disease. Little is known about their role in non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steato-hepatitis (NASH). We characterized the role of inflammasomes in NAFLD, NASH, and HCV. Gene expression and subcellular localization of P2X7R/P2X4R-NLRP3 and AIM2 inflammasome components were examined in histopathological preparations of 46 patients with biopsy-proven viral and metabolic liver disease using real-time PCR and immunofluorescence. P2X7R, P2X4R, and Caspase-1 are two- to five-fold more expressed in patients with NAFLD/NASH associated with chronic HCV infection than those with metabolic damage only (p ≤ 0.01 for all comparisons). The AIM2 inflammasome is 4.4 times more expressed in patients with chronic HCV infection, regardless of coexistent metabolic abnormalities (p = 0.0006). IL-2, a cytokine playing a pivotal role during chronic HCV infection, showed a similar expression in HCV and NASH patients (p = 0.77) but was virtually absent in NAFLD. The P2X7R-NLRP3 complex prevailed in infiltrating macrophages, while AIM2 was localized in Kupffer cells. Caspase-1 expression correlated with elastography-based liver fibrosis (r = 0.35, p = 0.02), whereas P2X7R, P2X4R, NRLP3, Caspase-1, and IL-2 expression correlated with circulating markers of disease severity. P2X7R and P2X4R play a major role in liver inflammation accompanying chronic HCV infection, especially when combined with metabolic damage, while AIM2 is specifically expressed in chronic viral hepatitis. We describe for the first time the hepatic expression of IL-2 in NASH, so far considered a peculiarity of HCV-related liver damage.     

Planar mirrors for image-based robot localization and 3-D reconstruction

Planar catadioptric vision sensors consist of a pinhole camera observing a scene being reflected on two (or more) planar mirrors. These systems have recently received an increasing attention because, unlike stereo cameras, can capture two views of the same scene without the need of hardware multi-camera synchronization and calibration. In this paper we explore the original scenario in which a robot manipulator, equipped with a pinhole camera on its end-effector, observes an unknown 3-D scene both directly and reflected through multiple mirrors. We present new multiple-view properties for this scenario and, based on these theoretical results, we present new image-based camera localization and new 3-D scene reconstruction algorithms. Extensive simulation and real-data experiments illustrate the theory and show the effectiveness of the proposed designs.     

Speed up of Video Enhancement based on Human Perception

This paper presents SUVEHP (speed up of video enhancement based on human perception), a human perception-based model oriented to reduce the computational time of digital video restoration. In particular, two specific hypothesis tests able to classify degraded frame regions are proposed. Classification is performed in agreement with regions visual significance in order to enable or inhibit motion compensated enhancement. The level of the proposed hypothesis tests is theoretically assessed. Moreover, extensive experimental results on video sequences affected by additive Gaussian noise show that SUVEHP speeds up some standard motion compensated denoisers up to 60%, preserving or even slightly increasing both the objective and subjective visual quality of the restored sequences.     

Wavelength Conversion Technologies

This paper reports a review of the different technologies used for wavelength conversion in wavelength-division multiplexed networks. The strengths and the weaknesses of the competing technologies, including optoelectronic wavelength conversion, four-wave mixing, difference frequency generation, cross-gain and cross-phase modulation in semiconductor optical amplifiers, are stressed with regard to conversion speed, transparency and regeneration of the converted signal.     

Interactions of white certificates with other policy instruments in Europe

In a tradable white certificate (TWC) scheme, each certificate issued represents a certain amount of energy saved. Used in conjunction with an energy-saving obligation on certain parties in the energy supply chain and with rules for trading, monitoring and verification established, an efficient market for energy savings in sectors not covered by the European Union (EU) Emissions Trading Scheme can be established. However, a plethora of other mechanisms are already in place to promote a more sustainable use of energy in Europe. This paper analyses the interactions (both potential and realised in existing schemes) between TWCs and other policy instruments including tradable green certificates, the European Union Emissions Trading Scheme, the European Union Energy Performance in Buildings Directive as well as taxes, subsidies and loans. Measures implemented through a TWC scheme that reduce the consumption of electricity can make targets under a tradable green certificate scheme easier to attain. Where a tradable green certificate scheme contains relative targets, the target should be increased to achieve the same absolute amount of renewable power. A TWC scheme can also reduce the number of allowances electricity generators will need to surrender under the EU Emissions Trading Scheme. By reducing the available emission rights in the National Allocation Plans, this effect is possible to counteract.

Semi-transparent blotches removal from sepia images exploiting visibility laws

This paper presents a novel model for the removal of semi-transparent blotches on the digitized copy of sepia archive photographs. As these defects cannot be successfully eliminated by conventional interpolation methods, a proper combination of a novel visual distortion and multiresolution analysis is used for performing user-independent detection and restoration. Extensive experimental results and comparative studies show the potential of the proposed model in terms of visual quality and computational complexity.     

Motor selection via impedance-matching for driving nonlinearly damped,resonant loads

This paper presents a novel method for selecting the most appropriate motor–gearhead combination for nonlinearly damped, resonant loads. The method extends to the nonlinear damping case the impedance-matching condition which is used to guarantee a maximum power transfer in linear network theory. In particular, the method is applicable in general to resonant loads where the damping is an odd and memoryless nonlinear function of the velocity. This condition is very common in biomimetic robotics, in particular when designing propulsion systems based on flapping appendages, such as wings or fins, in viscous fluids, such as air or water. The method is graphical in nature and is based on a power vs. impedance-mismatch factor. Such a factor is function of the ratio of the motor armature resistance to the load equivalent resistive impedance reflected at the motor armature, where the latter is nonlinear and depends on the desired kinematics as well as on the transmission ratio and efficiency. The method allows comparing, for a given desired appendage kinematics, all motor–gearhead combinations at once while taking into account all possible constraints such as maximum current, power, and torque.