3,431 research outputs found
Battery choice and management for New Generation Electric Vehicles
Different types of electric vehicles (EVs) have been recently designed with the aim of solving pollution problems caused by the emission of gasoline-powered engines. Environmental problems promote the adoption of new-generation electric vehicles for urban transportation. As it is well known, one of the weakest points of electric vehicles is the battery system. Vehicle autonomy and, therefore, accurate detection of battery state of charge (SoC) together with battery expected life, i.e., battery state of health, are among the major drawbacks that prevent the introduction of electric vehicles in the consumer market. The electric scooter may provide the most feasible opportunity among EVs. They may be a replacement product for the primary-use vehicle, especially in Europe and Asia, provided that drive performance, safety, and cost issues are similar to actual engine scooters. The battery system choice is a crucial item, and thanks to an increasing emphasis on vehicle range and performance, the Li-ion battery could become a viable candidate. This paper deals with the design of a battery pack based on Li-ion technology for a prototype electric scooter with high performance and autonomy. The adopted battery system is composed of a suitable number of cells series connected, featuring a high voltage level. Therefore, cell equalization and monitoring need to be provided. Due to manufacturing asymmetries, charge and discharge cycles lead to cell unbalancing, reducing battery capacity and, depending on cell type, causing safety troubles or strongly limiting the storage capacity of the full pack. No solution is available on the market at a cheap price, because of the required voltage level and performance, therefore, a dedicated battery management system was designed, that also includes a battery SoC monitoring. The proposed solution features a high capability of energy storing in braking conditions, charge equalization, overvoltage and undervoltage protection and, obviously, SoC information in order to optimize autonomy instead of performance or vice-versa
Publication and patent analysis of European researchers in the field of production technology and manufacturing systems
This paper develops a structured comparison among a sample of European researchers in the field of Production Technology and Manufacturing Systems, on the basis of scientific publications and patents. Researchers are evaluated and compared by a variegated set of indicators concerning (1) the output of individual researchers and (2) that of groups of researchers from the same country. While not claiming to be exhaustive, the results of this preliminary study provide a rough indication of the publishing and patenting activity of researchers in the field of interest, identifying (dis)similarities between different countries. Of particular interest is a proposal for aggregating analysis results by means of maps based on publication and patent indicators. A large amount of empirical data are presented and discusse
Supermassive Black Holes in Early-Type Galaxies: Relationship with Radio Emission and Constraints on the Black Hole Mass Function
Using recently published estimates - based on high spatial resolution
spectroscopy - of the mass M_{BH} of nuclear black holes for a sample of nearby
galaxies, we explore the dependence of galaxy nucleus emissivity at various
wavelengths on M_{BH}. We confirm an almost linear scaling of the black hole
mass with the baryonic mass of the host spheroidal galaxy. A remarkably tight
relationship is also found with both nuclear and total radio centimetric flux,
with a very steep dependence of the radio flux on M_{BH} (P\propto
M_{BH}^{2.5}). The high-frequency radio power is thus a very good tracer of a
super-massive black hole, and a good estimator of its mass. This, together with
the lack of significant correlations with the low-energy X-ray and far-IR flux,
supports the view that advection-dominated accretion is ruling the energy
output in the low-accretion rate regime. Using the tight dependence of total
radio power on M_{BH} and the rich statistics of radio emission of galaxies, we
derive an estimate of the mass function of remnants in the nearby universe.
This is compared with current models of quasar and AGN activity and of the
origin of the hard X-ray background (HXRB). As for the former, continuous
long-lived AGN activity is excluded by the present data with high significance,
whereas the assumption of a short-lived, possibly recurrent, activity pattern
gives remarkable agreement. The presently estimated black hole mass function
also implies that the HXRB has been produced by a numerous population (\sim
10^{-2} Mpc^{-3}) of moderately massive (M_{BH}\sim 10^7 M_\odot) black holes.Comment: 9 LaTex pages, 6 PS figures, accepted for publication in MNRA
Learning Musical Contour on a Tabletop
Many successful tabletop applications for music making have been developed, and the technology has been investigated from different perspectives. Yet, to date, despite optimistic claims regarding their potential as learning tools, their role in helping people to explore, acquire, and rea- son about musical concepts has been sparsely researched. We have developed an exploratory study around a simple tabletop application that allows people to make music using a visual representation of melodic contour. Our aim is to understand whether and how such system might help peo- ple to reason about music in terms of contour while at the same time affording an enjoyable music making experience to musically untrained people. Our findings suggest that the system has potential as a learning tool, especially for beginners, but tutoring is still necessary to acquire, use, and express concepts precisely
Clustering of the Diffuse Infrared Light from the COBE DIRBE maps. III. Power spectrum analysis and excess isotropic component of fluctuations
The cosmic infrared background (CIB) radiation is the cosmic repository for
energy release throughout the history of the universe. Using the all-sky data
from the COBE DIRBE instrument at wavelengths 1.25 - 100 mic we attempt to
measure the CIB fluctuations. In the near-IR, foreground emission is dominated
by small scale structure due to stars in the Galaxy. There we find a strong
correlation between the amplitude of the fluctuations and Galactic latitude
after removing bright foreground stars. Using data outside the Galactic plane
() and away from the center () we extrapolate
the amplitude of the fluctuations to cosec. We find a positive intercept
of nW/m2/sr at 1.25, 2.2,3.5 and 4.9 mic
respectively, where the errors are the range of 92% confidence limits. For
color subtracted maps between band 1 and 2 we find the isotropic part of the
fluctuations at nW/m2/sr. Based on detailed numerical and
analytic models, this residual is not likely to originate from the Galaxy, our
clipping algorithm, or instrumental noise. We demonstrate that the residuals
from the fit used in the extrapolation are distributed isotropically and
suggest that this extra variance may result from structure in the CIB. For
2\deg< \theta < 15^\deg, a power-spectrum analysis yields firm upper limits
of (\theta/5^\deg) \times\delta F_{\rm rms} (\theta) < 6, 2.5, 0.8, 0.5
nW/m2/sr at 1.25, 2.2, 3.5 and 4.9 mic respectively. From 10-100 mic, the upper
limits <1 nW/m2/sr.Comment: Ap.J., in press. 69 pages including 24 fig
Asymptotic defectiveness of manufacturing plants: an estimate based on process learning curves
The paper describes a method for a preliminary estimation of asymptotic defectiveness of a manufacturing plant based on the prediction of its learning curve estimated during a p-chart setting up. The proposed approach provides process managers with the possibility of estimating the asymptotic variability of the process and the period of revision of p-chart control limits. An application of the method is also provided
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