Search results for "force"
showing 10 items of 3423 documents
Optimization of cogging force in a linear permanent magnet generator for the conversion of sea waves energy
2015
In this paper an approach to the optimization of cogging force in a linear permanent magnet generator for the conversion of sea waves energy is presented. We have optimized the cogging force of a linear permanent magnet generator by using a 3D FEM parametric simulation. Several possible design solutions have been computed. A generator has been built and the results of the minimization procedure has been experimentally validated.
The Authorities’ Attitude Towards Treasure Hunting
2012
Shortly after the fall of the Bastille, a London newspaper was scandalized that people had been imprisoned there for mere trifles. Among the prisoners listed was a certain Girard, allegedly a treasure seeker.1 Was treasure seeking indeed merely a trifling offence? What had the courts and law enforcement agencies of premodern Britain and Europe to say about it? As we have seen in Chapter 1, treasure hunting as such was hardly ever illegal. It was, however, riddled with legal difficulties. What percentage of his find would the treasure hunter actually get? What would the fisc demand for the prince’s coffers? In addition to these juridical problems, an important part of pre-modern treasure hun…
Dynamic anomalies at the glass transition of organic van der Waals liquids
1993
Abstract The paper discusses the question of whether there is a characteristic temperature T c above the calorimetric glass transition temperature T g . Mode-coupling theory (MCT) predicts a crossover from liquid- to solid-like dynamics at T c . Neutron scattering and gradient NMR experiments have been carried out to test MCT using the molecular van der Waals liquid ortho -terphenyl as a model system. A significant anomaly of the Debye—Waller factor and a “decoupling” of self-diffusion from viscosity support the MCT predictions. A critical discussion of the relevance of such tests and of the limitations of neutron scattering is presented.
Heptane adsorption in silicalite-1 : molecular dynamics simulation.
2009
Molecular dynamics (MD) simulations have been used to study the adsorption process of n-heptane molecules in silicalite-1 at 300 K. MD simulated results were compared to experimental neutron diffraction (ND) and experimental self-diffusion coefficients. The analysis of MD data indicated a packing of the adsorbed molecules around 4 mol./u.c., which is not the consequence of an enthalpic effect but of an entropic effect. The role of the n-heptane chain flexibility (cis–trans conformation) in relation with the silicalite-1 channel type (straight versus sinusoidal) was outlined and enabled to understand the mobility change arising at 4 mol./u.c., according to previous experimental results. The …
Dynamics of Copolymer Micelles in a Homopolymer Melt: Influence of the Matrix Molecular Weight
2000
We have studied the dynamics of styrene−isoprene (SI) block copolymer micelles in a matrix of linear entangled polyisoprene (PI) chains, using forced Rayleigh scattering (FRS) and dynamic mechanica...
Are compliance constants ill-defined descriptors for weak interactions?
2013
Just as the potential energy can be written as a quadratic form in internal coordinates, so it can also be expanded in terms of generalized forces. The resulting coefficients are termed compliance constants. In this article, the suitability of compliance constants as non-covalent bond strength descriptors is studied (a) for a series of weakly bound hydrogen halide–rare gas complexes applying a configuration interaction theory, (b) for a double stranded DNA 4-mer using approximate density functional methods and finally (c) for a double stranded DNA 20-mer using empirical force fields. Our results challenge earlier studies, which concluded the inappropriateness of compliance constants as soft…
A comparison between a two feedback control loop and a reinforcement learning algorithm for compliant low-cost series elastic actuators
2020
Highly-compliant elastic actuators have become progressively prominent over the last years for a variety of robotic applications. With remarkable shock tolerance, elastic actuators are appropriate for robots operating in unstructured environments. In accordance with this trend, a novel elastic actuator was recently designed by our research group for Serpens, a low-cost, open-source and highly-compliant multi-purpose modular snake robot. To control the newly designed elastic actuators of Serpens, a two-feedback loops position control algorithm was proposed. The inner controller loop is implemented as a model reference adaptive controller (MRAC), while the outer control loop adopts a fuzzy pr…
Skilled workforce scheduling in Service Centres
2009
Abstract The Skilled Workforce Project Scheduling Problem (SWPSP) is a complex problem of task scheduling and resource assignment that comes up in the daily management of many company Service Centres (SC). The SWPSP considers many real characteristics faced daily by the SC: client-company service quality agreements that establish maximum dates for the beginning and the end of tasks with penalties for delays, criticality levels indicating the client-priority in processing each task, generalized precedence relationships that can produce cycle structures, time period and percentage time lags and variable task durations depending on the worker executing the task. Furthermore, the SC workforce i…
Springback Evaluation In Basic Sheet Metal Stamping Processes
2000
In the present paper a measurement technique based on the shadow moire method has been set up in order to evaluate the springback phenomenon in deep drawing operations. Two proper coefficients are introduced to quantitatively describe the effect considered. In particular the proposed technique is able to acquire the final profile of the drawn parts along one or more generatrices, once extracted out from the dies and to compare such profile with the ideal one derived from the dies CAD geometry. The proposed technique has been applied to an axysimmetrical deep drawing operation and moreover the influence of the blankholder force level and of the lubricating conditions have been taken into acc…
An Optical Technique for Springback Measurement in Axisymmetrical Deep Drawing Operations
2001
Abstract In this paper, a measurement technique based on the shadow moire method has been set up to evaluate the springback phenomenon in deep drawing operations. Two proper coefficients are introduced to quantitatively describe the investigated effect. In particular, the proposed technique is able to acquire the final profile of the drawn parts along one or more lateral contour, once extracted out from the dies, and compare such profile with the ideal one derived from the dies CAD geometry. The proposed technique has been applied to an axisymmetrical deep drawing operation, and, moreover, the influence of the blankholder force level and lubricating conditions has been taken into account. T…