1,720,957 research outputs found
Integrated design tools for model-based development of innovative vehicle chassis and powertrain systems
No full textThe paper provides a quick overview on system integration methodologies for advanced vehicle chassis and powertrains through an extension of the model-based design concept. Physics modeling and Driver-In-the-Loop (DIL) simulation techniques are described with an eye on the related hardware and software tools.
In greater detail, the design workflow pivots around a state-of-the-art device: the Driver-In-the-Loop simulator, where subjective, “human” factors can be taken into account together with objective, engineering factors. A framework of complementary tools with integrated functionalities supports the designer in order to merge traditional chassis engineering with advanced vehicle dynamics skills and modern control system design.
An interactive design framework is proposed in order to report the authors’ experience. A self-developed utility for suspension and steering design, specifically conceived for intuitive integration in the design process, is also presented
ON THE TORQUE STEER PROBLEM FOR FRONT-WHEEL-DRIVE ELECTRIC CARS
No full textBeyond the well-known benefits of electric and hybrid powertrains in terms of environmental impact, the peculiar torque curve of electric motors for automotive applications offers extensive opportunities for improved vehicle dynamics control, such as yaw moment control through the application of different tractive forces across the axle: the so-called Torque Vectoring [1]. This is made possible for instance by fitting an independent motor on each wheel of a drive axle.
On the other side, whenever Torque Vectoring is achieved on the front axle it can give birth to the so called torque steer effect: an undesirable influence of tractive or braking torque on the steering [2]. This is perceived by the driver as a “tugging or pulling sensation in the steering wheel, or a veering of the vehicle from the intended path” [3]. The steering feedback and self-aligning properties, often considered a vital portion of the feedback required for safe and intui-tive driving control [4, 5], are thus jeopardized, especially under heavy acceleration. This is very similar to what can be experienced on front-wheel-drive cars featuring a high torque-to-weight ratio, often requiring the adoption of a LSD or active differential device in order to op-timize traction capabilities [6].
The paper presents an approach to the torque steer problem on high-performance electric and hybrid vehicles, where the effects of suspension and steering geometry as well as tyre con-tact patch load variation are taken into account and various design solutions are proposed as an improvement. The VI-grade® software tools for vehicle dynamics analysis are adopted, also in co-simulation with MATLAB-Simulink® whenever an active control strategy is used. The impact on steering feedback quality is assessed through a testing campaign carried out on a state-of-the-art driving simulator
Posizionamento di mezzi in moto ad alta velocità mediante tecniche GNNS ad alta frequenza: confronto con i sensori utilizzati nei sistemi di acquisizione di bordo
No full textIl posizionamento di veicoli in moto ad alta velocità è affetto da una vasta serie di problematiche dovute alla frequenza di acquisizione del segnale e della correzione differenziale. Le difficoltà maggiori sono legate al mantenimento della stabilità di posizionamento in condizioni di visibilità del cielo sfavorevoli e al bisogno di acquisire con frequenze elevate al fine di non perdere informazioni importanti legate alla traiettoria del mezzo in moto.
Le informazioni di posizione ottenute con sistema satellitare possono essere convenientemente integrate con sensori comunemente impiegati per la telemetria, al fine di riferire geograficamente i dati relativi al moto e di valutare l’influenza della traiettoria su tali dati.
I risultati di questa metodologia di rilevamento sono legati fortemente al tipo di strumentazione utilizzata ed alle condizioni ambientali al contorno. E' incoraggiante il comportamento riscontrato in condizioni favorevoli, da approfondire il problema della frequenza di correzione.
Il presente contributo descrive la procedura utilizzata e i risultati ottenuti strumentando un’autovettura impiegata nell’automobilismo da competizione.
GPS positioning of high speed vehicles is limited by several problems due to the signal sampling
rate and differential correction issues. The preservation of a stable positioning in unfavorable
visibility conditions and the need of high sampling rate for the trajectory integrity are the most
relevant difficulties to be considered.
The presented results are strongly dependent on involved instrumentation and external conditions.
Behavior showed in favorable environmental conditions is encouraging; the problem of the
correction frequency needs to be more in depth analyzed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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