Stable and highly sensitive gas sensors based on semiconducting oxide nanobelts

©2002 American Institute of Physics. The electronic version of this article is the complete one and can be found online at: : http://link.aip.org/link/?APPLAB/81/1869/1DOI:10.1063/1.1504867Gas sensors have been fabricated using the single-crystalline SnO₂ nanobelts. Electrical characterization showed that the contacts were ohmic and the nanobelts were sensitive to environmental polluting species like CO and NO₂ , as well as to ethanol for breath analyzers and food control applications. The sensor response, defined as the relative variation in conductance due to the introduction of the gas, is 4160% for 250 ppm of ethanol and 21550% for 0.5 ppm NO₂ at 400 °C. The results demonstrate the potential of fabricating nanosized sensors using the integrity of a single nanobelt with a sensitivity at the level of a few ppb

Design and Analysis of a Fibre-Shaped Micro-Actuator for Robotic Gripping

A prototype of an automatic micropositioning system was developed. This prototype uses a shape memory alloy (SMA) actuator, a dedicated PI controller and a piece of software to command a desired motion profile for the actuator. The proposed micropositioning system is characterized by a 4 mm stroke, a 1 μm resolution and a 70 g nominal force and can be commanded directly from a personal computer and without human retroaction. The closed loop positioning resolution (1 μm) is obtained in spite of inaccurate system behaviour during its movement

A Compliant PKM Mesomanipulator: Kinematic and Dynamic Analyses.

The kinematic and dynamic analyses of a PKM mesomanipulator are addressed in this paper: the proposed robot architecture allows only pure translations for the mobile platform, while the presence of flexure hinges introduces compliance into the structure. The analytical solutions to direct and inverse kinematic problems are evaluated after a brief introduction of the basic adopted nomenclature, the manipulator workspace and the robot singularity configurations are then described, and the analytical solution to the inverse dynamic problem is presented. Thereafter, an overview on some of the simulations results obtained through a software implementation of the described algorithms is addressed, and the most salient aspects of this topic are summarized in the final conclusions

Innovative modular SMA actuator

A modular design for a shape memory actuator is proposed. The actuator is able to perform linear movements, while the modularity allows force and/or stroke improvements. Experimental results show how the behavior of the proposed implementation is sufficient for a wide class of problems and can be improved with proper developments

Robotics rehabilitation of the elbow based on surface electromyography signals

Physical rehabilitation based on robotic systems has the potential to cover the patient’s need of improvement of upper extremity functionalities. In this article, the state of the art of resistant and assistive upper limb exoskeleton robots and their control are thoroughly investigated. Afterward, a single-degree-of-freedom exoskeleton matching the elbow–forearm has been advanced to grant a valid rehabilitation therapy for persons with physical disability of upper limb motion. The authors have focused on the control system based on the use of electromyography signals as an input to drive the joint movement and manage the robotics arm. The correlation analysis between surface electromyography signal and the force exerted by the subject was studied in objects’ grasping tests with the purpose of validating the methodology. The authors developed an innovative surface electromyography force–based active control that adjusts the force exerted by the device during rehabilitation. The control was validated by an experimental campaign on healthy subjects simulating disease on an arm, with positive results that confirm the proposed solution and that open the way to future researches

Automatic Procedures as Help for Optimal Cam Design

ABSTRACT In this work we suggest a synthesis of recent results obtained on the application of soft-computing techniques to solve typical automatic machines design problems. Particularly, here we show an optimization method based on the application of a specialized algorithms ruled by a generalized software procedures, which appears able to help the mechanical designer in the first part of the design process, when he has to choose among different wide classes of solutions. In this frame, among the different problems studied, we refer here about the choice of the best class of motion profiles, to be imposed to a cam follower, which must satisfy prefixed design specifications. A realistic behaviour of the system is considered and the parameter model identification is set up by a soft computing procedure. The design, based on theoretical knowledge, sometimes is not sufficient to fulfil desired dynamical performances, in this situation, a residual optimization is achieved with the help of another optimizing method. The problem of a cam-follower design is presented. A class of motion profiles and the best theoretical motion profile is selected by an evolutionary algorithm. A realistic model is considered and its parameter identification is achieved by a genetic algorithm. The residual optimization is achieved by a servomotor optimized by another genetic algorithm. Evolutionary approach is used during all the design process and, as was shown, it allows really interesting performance in terms of simplicity of the design process and in terms of performance of the product

Precision point design of a cam indexing mechanism

This work regards on the design of a cylindrical cam indexing mechanism with a motion law that passes through a positional precision point. A numerical algorithm is proposed to solve this problem and, particularly, a genetic algorithm. The algorithm and the encoding of the problem are described

A Novel Logic and Approach to Speed up Simulation and Analysis of Production Systems

The paper describes a novel logic to model, simulate and analyze production systems using Discrete Event Simulation tools. An adaptable and flexible DES model has been developed to represent different manufacturing environments. The goal of the proposed DES-based parametric model is to offer to industrial analysts a compact, fast and easy way to configure and use decision support tools. The logic is based on elementary structures with a vertical multilayer architecture that permits entities to access and loop in multiple times. Since it has been assumed manufacturing systems are combination of elementary parts, the architecture of the model becomes quite simple since representing few structures only, and the simulation of heterogeneous systems is the result of as many iterations as needed by a user. This approach is adaptable both to SMEs and large companies, permitting to avoid the use of dedicated SW and allocated skilled person

Non-separability, locality and criteria of reality: a reply to Waegell and McQueen

Using a ‘reformulation of Bell’s theorem’, Waegell and McQueen (2020) argue that any empirically adequate theory that is local and does not involve retro-causation or fine-tuning must be a many-worlds theory. They go on to analyze several prominent many-worlds interpretations and conclude that non-separable many-worlds theories whose ontology is given by the wavefunction involve superluminal causation, while separable many-worlds theories (e.g. Waegell, 2021; Deutsch and Hayden 2000) do not. I put forward three claims. (A) I challenge their argument for relying on a non- trivial, unquestioned assumption about elements of reality which allows Healey’s approach (Healey, 2017b) to evade their claim. In an attempt to respond to (A), Waegell and Mc- Queen may restrict their claim to theories which satisfy such an assumption, however, I also argue that (B) their argument fails to prove even the so weakened claim, as exem- plified by theories that are both non-separable and local. Finally, (C) by arguing for the locality of the decoherence-based Everettian approach (Wallace, 2012) I refute Waegell and McQueen’s claim that wavefunction-based ontologies, and more generally non-separable ontologies, involve superluminal causation. I close with some doubtful remarks about separable Everettian interpretations as compared to non-separable ones

Automating the simulation of SME processes through a discrete event parametric model

At the factory level, the manufacturing system can be described as a group of processes governed by complex weaves of engineering strategies and technologies. Decision- making processes involve a lot of information, driven by managerial strategies, technological implications and layout constraints. Many factors affect decisions, and their combination must be carefully managed to determine the best solutions to optimize performances. In this way, advanced simulation tools could support the decisional process of many SMEs. The accessibility of these tools is limited by knowledge, cost, data availability and development time. These tools should be used to support strategic decisions rather than specific situations. In this paper, a novel approach is proposed that aims to facilitate the simulation of manufacturing processes by fast modelling and evaluation. The idea is to realize a model that is able to be automatically adapted to the user’s specific needs. The model must be characterized by a high degree of flexibility, configurability and adaptability in order to automatically simulate multiple/heterogeneous industrial scenarios. In this way, even a SME can easily access a complex tool, perform thorough analyses and be supported in taking strategic decisions. The parametric DES model is part of a greater software platform developed during COPERNICO EU funded project