Stories and signs in an e-learning environment for deaf people

An important field for model-driven development of interfaces is the consideration of users with disabilities. Interface design for deaf people presents specific problems, since it needs to be based on visual communication, incorporating unusual forms of interaction, in particular gesture-based ones. Standard solutions for model-driven development of visual interfaces lack specific constructs for structuring these more sophisticated forms of interaction. This paper discusses such issues in the context of the development of a deaf-centered e-learning environment. Sign Languages enter this context as a suitable alternative communication code, both in video form and through one of their most successful written forms, namely SignWriting.     

Use of web-based materials to teach electric circuit theory

Beginning fall 2001, the Electrical Engineering Department at Texas A&M University, College Station, significantly altered the instructional philosophy of the ELEN 214 Electric Circuit Theory course by introducing more engineering design into the curriculum and adopting the WebCT-based interactive homework submission system. This paper will discuss the use of the Quiz tool within WebCT for the construction of question banks and their publication to a WebCT server. An example, deriving mathematical expressions, which describes electric circuit behavior and helps customize the homework problems to each individual student, are discussed. In other words, in a class of 200 students, each student is presented with an individual homework assignment with a unique set of problems not repeated to anyone else via WebCT. A help desk staffed by senior undergraduates assists the course students in completing the WebCT-based homework on time. WebCT is an essential ingredient in the delivery of the course. The approach presented in this paper can be adapted to any other course in engineering/science that involves mathematical calculations. So far, the course evaluations suggest that the students are more motivated and excited about electrical and computer engineering as a career.     

Mechatronic analysis of a complex transmission chain for performance optimization in a machine tool

Mechatronic models of complex mechanical systems allow to assemble reliable simulators, which can be used to test alternative choices made at component level. When the complexity of the system is significant, however, it is neither easy to model the interactions among different elements, nor immediate to identify the components responsible for a possible loss of performance of the system. Based on a detailed linear model of a complex transmission chain used within a large size machine tool, this paper contributes presenting a methodology, supported by modal analysis, to quantify the sensitivity of each vibration mode to the stiffness of each component. A nonlinear simulator of the transmission has been derived, too, and its remarkable performance in reproducing the experiments is demonstrated. Insight on the role of Coulomb friction is also provided, together with a practical way to split the overall friction between motor and load sides.     

Deep cryogenic treatment of AISI 302 stainless steel: Part I – Hardness and tensile properties

The effects of deep cryogenic treatment (DCT) on the static mechanical properties of the AISI 302 austenitic stainless steel were investigated through experimental testing. The results of the tensile and hardness tests are discussed and compared to data and microstructural observations from the DCT literature concerning the same class of steel. In addition, the influence of two important treatment parameters, such as the soaking-time and the minimum temperature, is analysed through a full factorial design of experiments (DOE) and by means of a first approximation model in order to obtain confirmation and suggestions about the possible use of the DCT as a standard practice to improve the mechanical properties of stainless steels. A particular focus is given to the registered changes of the elastic modulus and of the hardness as representative measures of two different deformation mechanisms.     

Simulation of the entanglement creation for identical particles scattering in a 2D system

In recent years the dynamics of entanglement formation between two distinguishable charged particles has been investigated for scattering events in bulk semiconductors. The aim of this work is to overcome the hypothesis of distinguishable carriers. Here we present a quantitative evaluation of the entanglement dynamics for electron-electron collisions in a 2D system applying a method, suitable for indistinguishable particles, based on the Slater rank and the von Neumann entropy of the reduced density matrix. The quantum entanglement of both spatial and spin degrees of freedom is computed for various initial conditions of the system.     

Design, implementation and clinical tests of a wire-based robot for neurorehabilitation.

This paper presents the development of and clinical tests on NeReBot (NEuroREhabilitation roBOT): a three degrees-of-freedom (DoF), wire-driven robot for poststroke upper-limb rehabilitation. Basically, the robot consists of a set of three wires independently driven by three electric motors. The wires are connected to the patient's upper limb by means of a splint and are supported by a transportable frame, located above the patient. By controlling wire length, rehabilitation treatment (based on the passive or active-assistive spatial motion of the limb) can be delivered over a wide working space. The arm trajectory is set by the therapist through a very simple teaching-by-showing procedure, enabling most common "hands on" therapy exercises to be reproduced by the robot. Compared to other rehabilitation robots, NeReBot offers the advantages of a low-cost mechanical structure, intrinsically safe treatment thanks to the use of wires, high acceptability by the patient, who does not feel constrained by an "industrial-like" robot, transportability (it can be easily placed aside a hospital bed and/or a wheelchair), and a good trade-off between low number of DoF and spatial performance. These features and the very encouraging results of the first clinical trials make the NeReBot a good candidate for adoption in the rehabilitation treatment of subacute stroke survivors. Clinical trials were performed with a 12-patient experimental group and a 12-patient control group. Resulted that the patients who received robotic therapy in addition to conventional therapy showed greater reductions in motor impairment (in terms of Medical Research Council score, the upper limb subsection of the Fugl-Meyer score, and the Motor Status Score) and improvements in functional abilities (as measured by the Functional Independence Measure and its motor component). No adverse effects occurred and the robotic approach was very well accepted. According to these results, the NeReBot therapy may efficaciously complement standard poststroke multidisciplinary rehabilitation and offer novel therapeutic strategies for neurological rehabilitation.     

Multiairport Capacity Management: Genetic Algorithm With Receding Horizon

The inability of airport capacity to meet the growing air traffic demand is a major cause of congestion and costly delays. Airport capacity management (ACM) in a dynamic environment is crucial for the optimal operation of an airport. This paper reports on a novel method to attack this dynamic problem by integrating the concept of receding horizon control (RHC) into a genetic algorithm (GA). A mathematical model is set up for the dynamic ACM problem in a multiairport system where flights can be redirected between airports. A GA is then designed from an RHC point of view. Special attention is paid on how to choose those parameters related to the receding horizon and terminal penalty. A simulation study shows that the new RHC-based GA proposed in this paper is effective and efficient to solve the ACM problem in a dynamic multiairport environment     

Novel tri- and tetrafunctional cholic acid-based initiators for the synthesis of star-shaped poly(L-lactide)s

In this investigation, two novel multifunctional initiators for ring-opening polymerization were synthesized in three steps starting from cholic acid. Thus, cholic acid (1a) and its methyl ester (1b) were quantitatively transformed, via solvent-free reaction with succinic anhydride, to the corresponding 3, 7, 12-tri-hemisuccinate derivatives (3a-b). The polyacidic compounds (3a-b) were treated with thionyl chloride affording the corresponding acyl chlorides 4a-b which, in turn, were reacted with ethylene glycol to give the derivatives 2a-b having three and four primary alcohol end groups. These compounds, fully characterized by ¹H, ¹³C NMR and mass spectrometry, have been assessed as initiators in the ring-opening polymerization of L-lactide using stannous octanoate as catalyst. The resulting three- and four-armed star-shaped poly(L-lactide)s, which were characterized by ¹H NMR, SEC, DSC and TGA analysis, were amorphous, and their glass transition temperatures ranged from 13.7 to 36.5 °C. Additionally, some cholic acid-based star-shaped polylactic structures recently published have been critically reconsidered showing that these molecules, described as star polymers, were actually linear polymers.     

Digital light processing of ceramic components from polysiloxanes

Additive manufacturing using photocurable polymers is one method to answer the increased demand of ceramic structures with complicated morphology by fabricating ceramic parts with high resolution and good surface quality. We introduce here a new method to fabricate SiOC ceramic structures by utilizing a simple physical blend between two different preceramic polysiloxanes, one providing photosensitive acrylate groups while the other one a high ceramic yield. Different blend ratios have been realized and respectively optimized concerning the printing additives and setting times to fabricate exact replications of highly complex polysiloxane structures by Digital Light Processing. After pyrolysis, a uniform, homogenous shrinkage was observed yielding dense, pore- as well as crack-free SiOC ceramics. By adjusting the ratio between the different polysiloxanes, parameters such as the ceramic yield, shrinkage, chemical composition and resolution after pyrolysis could be tailored in a wide range of values.