169,757 research outputs found
Voltage-current based algorithm for the on-line estimation of equivalent internal resistance of Lithium-Cobalt-Oxide cells at different aging levels
No full textThis paper deals with the problem of the identification of lithium cell parameters to be correlated with the cell level of aging. Three identical Lithium-Cobalt-Oxide (LCO) commercial cells at three different State-of-Life (SOL) values are experimentally tested, and two parameter estimations are applied, focusing on the cell internal resistance, which appears significantly sensitive to different cell aging levels. After displaying how the single cells under study can be calibrated through an off-line procedure by means of equivalent electrical circuit approach, the development of a voltage-current based algorithm to be applied on-line and capable of estimating an 'equivalent internal resistance' to be correlated with cell SOL is proposed. The robustness and the online applicability of the algorithm is tested on different realistic scenarios, as well as different State-of-Charge levels. Results confirm the capability of the proposed algorithm to be potentially applied for the online State-of-Life estimation for lithium cells
On the hybridization of microcars with hybrid ultracapacitors and Li-Ion batteries storage systems
No full textThe objective proposed by the EU to drastically reduce vehicular CO2 emission for the years up to 2030 requires an increase of propulsion systems- efficiency, and accordingly, the improvement their technology. Hybrid electric vehicles could have a chance of achieving this, by recovering energy during braking phases, running in pure electric mode and allowing the internal combustion engine to operate under better efficiency conditions, while maintaining traditionally expected vehicle performances (mileage, weight, available on-board volume, etc.). The energy storage systems for hybrid electric vehicles (HEVs) have different requirements than those designed for Battery Electric Vehicles (BEVs); high specific power is normally the most critical issue. Using Li-ion Batteries (LiBs) in the designing of on-board Energy Storage Systems (ESS) based only on power specifications gives an ESS with an energy capacity which is sufficient for vehicle requirements. The highest specific power LiBs are therefore chosen among those technologically available. All this leads to an ESS design that is strongly stressed over time, because current output is very high and very rapidly varies, during both traction and regeneration phases. The resulting efficiency of the ESS is correspondingly lowered, and LiBs lifetime can be relevantly affected. Such a problem can be overcome by adopting hybrid storage systems, coupling LiBs and UltraCapacitors (UCs); by properly dimensioning and controlling the ESS- components, in fact, the current output of the batteries can be reduced and smoothed, using UCs during transients. In this paper, a simulation model, calibrated and validated on an engine testbed, has been used to evaluate the performances of a hybrid storage HEV microcar under different operative conditions (driving cycles, environment temperature and ESS State of Charge). Results show that the hybridization of the powertrain may reduce fuel consumption by up to 27%, while LiBs lifetime may be more than doubled
Size shrinking of composite bosons for increasing density in the BCS to Bose-Einstein crossover
No full textWe consider a system of fermions in the continuum case at zero temperature, in the strongcoupling
limit of a short-range attraction when composite bosons form as bound-fermion pairs. We examine
the density dependence of the size of the composite bosons at leading order in the density (\dilute limit"),
and show on general physical grounds that this size should decrease with increasing density, both in three
and two dimensions. We then compare with the analytic zero-temperature mean-eld solution, which
indeed exhibits the size shrinking of the composite bosons both in three and two dimensions. We argue,
nonetheless, that the two-dimensional mean-eld solution is not consistent with our general result in the
\dilute limit", to the extent that mean eld treats the scattering between composite bosons in the Born
approximation which is known to break down at low energy in two dimensions
Ageing effects on batteries of high discharge current rate
No full textAmong the various stress factors determining the ageing of the battery when cycled at high discharge currents, the temperature increase was identified as the main operating mechanism. In order to quantify the improvement of the battery pack cycle life with load levelling, a model was developed to calculate the temperature inside the battery. A curve correlating the battery cycle number with the internal temperature of the battery was designed. As a result, it was calculated that the differential temperature decreased from 11°C in the high stressed battery down to 1.5 °C in the load-levelled system. © 2017 MOBI -Mobility, Logistics and Automotive Technology Research Centre
High-Detail Fault Segmentation: Deep Insight into the Anatomy of the 1983 Borah Peak Earthquake Rupture Zone (Mw 6.9, Idaho, USA)
No full textFollowing observations made in a survey campaign along the Lost River Fault (Idaho, USA) in 2019, we integrate both original and previously published data to obtain a detailed segmentation of the fault sections that failed in the 1983 Borah Peak earthquake (Mw 6.9). The earthquake ruptured the topographic surface with an oblique-normal faulting mechanism, activating two SW-dipping fault segments (Thousand Springs and Warm Springs) and a branching SSW-dipping fault (Arentson Gulch Fault) and producing coseismic surface ruptures with up to 3m of vertical separation. We augment the 1983 earthquake description by interpreting high-resolution topography and fault mapping. We use quality vertical separation data, rupture zone width measurements, and fault slip data to analyze major and minor structural-geometric complexities, highlighting a partition of the deformation and a fault segmentation into four detail levels (i.e., segments, sections, subsections, and sectors). Our work provides new details of the 1983 Borah Peak earthquake, constraints for paleoseismic and seismotectonic studies, and a methodological approach applicable in other areas of the world. Our fault-slip data show variations along faultstrike that we interpret as kinematic partitioning. In 1983, the main southern segment had a large rupture zone width, while the northern segment localized the deformation. The distributed ruptures accommodate a large portion of the rupture length (~19.5 km versus 31 km for the main rupture) and displacement (~66%). 83% of the surface faulting and 80% of the displacement are located at the hanging wall of the main rupture. There is a strong correlation between vertical separation, rupture zone width, rupture position (footwall or hanging wall), and fault geometry. We highlight the control of the obliquity and kinematic partitioning in the surface expression of the earthquake propagation. We interpret the coseismic (i.e., 1983) and long-term (i.e., Quaternary) behavior, showing that the two activated segments had similar cumulated behaviors in distributing the deformation between synthetic and antithetic ruptures, despite the different geometries. Our results have implications for fault rupture behavior with application to rupture hazard. © 2022. Simone Bello et al. Exclusive Licensee GeoScienceWorld. Distributed under a Creative Commons Attribution License (CC BY 4.0
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Experimental Demonstration of Linear Least Squares-based Longitudinal Power Monitoring over a Raman-amplified C+L Link
No full textWe present the first experimental demonstration of a linear least squares-based longitudinal power monitoring algorithm over a C+L link with full backward Raman amplification, transmitting 64-GBaud PDM-QPSK signals over 9x60-km spans of SMF
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
- …
