Out-of-equilibrium dynamics of repulsive Fermi gases in quasi-periodic potentials: a Density Functional Theory study

The dynamics of a one-dimensional two-component Fermi gas in the presence of a quasi-periodic optical lattice (OL) is investigated by means of a Density Functional Theory approach. Inspired by the protocol implemented in recent cold-atom experiments, designed to identify the many-body localization transition, we analyze the relaxation of an initially prepared imbalance between the occupation number of odd and of even sites. For quasi-disorder strength beyond the Anderson localization transition, the imbalance survives for long times, indicating the inability of the system to reach local equilibrium. The late time value diminishes for increasing interaction strength. Close to the critical quasi-disorder strength corresponding to the noninteracting (Anderson) transition, the interacting system displays an extremely slow relaxation dynamics, consistent with sub-diffusive behavior. The amplitude of the imbalance fluctuations around its running average is found to decrease with time, and such damping is more effective with increasing interaction strengths. While our study addresses the setup with two equally intense OLs, very similar effects due to interactions have been observed also in recent cold-atom experiments performed in the tight-binding regime, i.e. where one of the two OLs is very deep and the other is much weaker.Comment: Published version, 8 pages, 5 figure

toward a real time reconfiguration of self adaptive smart assembly systems

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real time assistance to manual assembly through depth camera and visual feedback

Abstract The current fourth industrial revolution significantly impacts on production processes. The personalized production paradigm enables customers to order unique products. The operators assemble an enormous component variety adapting their process from product to product with limited learning opportunities. Digital technologies are increasingly adopted in production processes to improve performance and quality. Considering this framework, this research proposes a hardware/software architecture to assist in real-time operators involved in manual assembly processes. A depth camera captures human motions in relation with the workstation environment whereas a visual feedback guides the operator through consecutive assembly tasks. An industrial case study validates the architecture

towards optimum energy utilization by using the inverters for industrial production

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Plastic Optical Fiber pH Sensor Using a Sol-Gel Sensing Matrix

Current trends in optical sensors, such as miniaturization, flexibility and enhanced sensitivity, are indicating a new chemical route for the development of advanced multifunctional materials for optical applications. Those chemical technologies, which can be more easily customized and allows the inclusion of multiple functionalities within a unique preparation step, are bound to be progressively more and more applied to the preparation of optical materials.In this perspective, the sol-gel technology certainly represents one of the most promising chemical strategies, thanks to numerous advantages mainly related to simplicity and mild operative conditions. It enables creating a glass-like porous structure at room temperature by a two-step acid or base catalyzed reaction involving hydrolysis and condensation, starting with metal alkoxides M(OR)4, which transforms into a rigid three-dimensional metal-oxide network (Brinker, 1990). The sol\u2013gel process has been proved to be flexible enough for an efficient incorporation of organic polymer chains that can behave as flexible links between the metal-oxide domains in the inorganic network, in particular when they are bearing reactive groups that can be involved in the hydrolysis\u2013condensation reactions. The resulting materials are known as organic\u2013inorganic hybrids (Schmidt, 2000), also commonly designated as ceramers due to the combination of the properties of ceramics (high modulus, thermal stability and low coefficient of thermal expansion) with those of organic polymers (high ductility, molecular flexibility and low temperature processing). These materials are often also known as phase-interconnected nanocomposites because of the high level of interconnection between the two phases with domain phase sizes approaching the nanometer scale. Ceramers have a huge potential for application in a variety of advanced technologies (Eckert, 2001; Sanchez, 2011; Kickelkick, 2006), both as structural materials and functional materials, such as catalyst supports, protective coatings (Messori, 2003, 2004a); Toselli, 2007; Fabbri, 2008), sensors (Rovati, 2011; Fabbri, 2011), and active glasses.Optical fiber sensors are traditionally obtain by fully-inorganic sol-gel process that allows the creation of Si-O-Si linkages between the silica core of the optical fiber and the silica porous matrix deriving from the jellification of the sensitive dye-doped colloidal suspension (Cao, 2005). However, this approach cannot be easily applied in the case of plastic optical fibers, due to the ineffective interaction between the organic PMMA optical fiber core (Lin, 2000).The approach proposed in this work consists in the fabrication of a pH sensor based on an organic-inorganic hybrid matrix obtained by a sol-gel process, doped with a pH sensitive indicator, to be applied at the tip of plastic optical fibers. Inside the sensitive element, the organic part of the hybrid glass, polyethylene oxide (PEO), plays a multiple role: (i) it allows good adhesion between the plastic optical fiber and the whole sensitive element; (ii) its weak hydrophilicity permits to tune the kinetic of response of the sensor by influencing thediffusion rate of the analyte inside the porous matrix and its interaction with the indicator; (iii) its nature of organic compound allows better physical and chemical interactions with the organic pH indicator dispersed in the hybrid matrix, thus reducing problems of leaching and enhancing the response rate of the sensor

Continuous haematic pH monitoring in extracorporeal circulation using a disposable florescence sensing element.

During extracorporeal circulation (ECC), blood is periodically sampled and analyzed to maintain the blood-gas status of the patient within acceptable limits. This protocol has well-known drawbacks that may be overcome by continuous monitoring. We present the characterization of a new pH sensor for continuous monitoring in ECC. This monitoring device includes a disposable fluorescence-sensing element directly in contact with the blood, whose fluorescence intensity is strictly related to the pH of the blood. In vitro experiments show no significant difference between the blood gas analyzer values and the sensor readings; after proper calibration, it gives a correlation of R>0.9887, and measuring errors were lower than the 3% of the pH range of interest (RoI) with respect to a commercial blood gas analyzer. This performance has been confirmed also by simulating a moderate ipothermia condition, i.e., blood temperature 32°C, frequently used in cardiac surgery. In ex vivo experiments, performed with animal models, the sensor is continuously operated in an extracorporeal undiluted blood stream for a maximum of 11 h. It gives a correlation of R>0.9431, and a measuring error lower than the 3% of the pH RoI with respect to laboratory techniques

Construction and evaluation of a disposable pH sensor based on a large core plastic optical fiber

The fabrication and characterization of a disposable optical fiber sensor for the detection of pH in the range 5-8 are described. The sensing element is a drop of sol-gel hybrid material containing phenol red and deposited onto the tip of a large core plastic optical fiber. This fiber is also exploited for the optical interrogation. This probe can be used as a disposable part of a measuring system. The dynamic range and temporal response of the sensor are here investigated

Disposable Fluorescence Optical pH Sensor for Near Neutral Solutions

The design, development and performance evaluation of a fluorescence-based pH sensor for on-line measurements is presented. The pKa of the sensing element has been calculated to be 7.9, thus the sensor is suitable for measurement of near neutral solutions. The sensor consists of a low-cost disposable polymer sensing probe, in contact with the solution under test, interrogated by an optoelectronic transduction system. The pH sensitive dye is based on fluorescein O-methacrylate, which has been covalently linked to a hydrogel matrix, realized through the use of HEMA (2-hydroxyethyl methacrylate), HDDA (1,6-hexanediol diacrylate) and PEGDA (polyethylene glycol diacrylate). The optical interrogation setup, together with the electronics, has been developed to acquire and process the fluorescence signal. The sensor works over a pH range between 6.5 and 9.0. In the range between 7.0 and 8.0, the sensor shows a linear behavior with a maximum linearity error of 5%. Thanks to the good performance of the sensing element and transduction system, the short term drift of the reading (measured over 40 min) is lower than 0.15%. The measuring system also exhibits good performance in terms of response time and reproducibility

Automatic assessment of the ergonomic risk for manual manufacturing and assembly activities through optical motion capture technology

Abstract Safeguard the operator health is nowadays a hot topic for most of the companies whose production process relies on manual manufacturing and assembly activities. European legislations, national regulations and international standards force the companies to assess the risk of musculoskeletal disorders of operators while they are performing manual tasks. Furthermore, international corporates typically require their partners to adopt and implement particular indices and procedures to assess the ergonomic risks specific of their industrial sector. The expertise and time required by the ergonomic assessment activity compels the companies to huge financial, human and technological investments. An original Motion Analysis System (MAS) is developed to facilitate the evaluation of most of the ergonomic indices traditionally adopted by manufacturing firms. The MAS exploits a network of marker-less depth cameras to track and record the operator movements and postures during the performed tasks. The big volume of data provided by this motion capture technology is employed by the MAS to automatically and quantitatively assesses the risk of musculoskeletal disorders over the entire task duration and for each body part. The developed hardware/software architecture is tested and validated with a real industrial case study of a car manufacturer which adopts the European Assembly Worksheet (EAWS) to assess the ergonomic risk of its assembly line operators. The results suggest how the MAS is a powerful architecture compared to other motion capture solutions. Indeed, this technology accurately assesses the operator movements and his joint absolute position in the assembly station 3D layout. Finally, the MAS automatically and quantitatively fill out the different EAWS sections, traditionally evaluated through time- and resource-consuming activities

Corrigendum: Corrigendum to 'Learning manual assembly through real-time motion capture for operator training with augmented reality"

Abstract The authors regret that The authors would like to apologise for any inconvenience caused