The latest pre-production vehicles on the market show that the major technical challenges posed by integrating a fuel cell system (FCS) within a vehicle—compactness, safety, autonomy, reliability, ...cold starting—have been met. Regarding the ongoing maturity of fuel cell systems dedicated to road transport, the present article examines the advances still needed to move from a functional but niche product to a mainstream consumer product. It seeks to address difficulties not covered by more traditional innovation approaches. At least in long-distance heavy-duty vehicles, fuel cell vehicles (FCVs) are going to play a key role in the path to zero-emissions in one or two decades. Hence the present study also addresses the structuring elements of the complete chain: the latter includes the production, storage and distribution of hydrogen. Green hydrogen appears to be one of the potential uses of renewable energies. The greener the electricity is, the greater the advantage for hydrogen since it permits to economically store large energy quantities on seasonal rhythms. Moreover, natural hydrogen might also become an economic reality pushing the fuel cell vehicle to be a competitive and environmentally friendly alternative to the battery electric vehicle. Based on its own functional benefits for on board systems, hydrogen in combination with the fuel cell will achieve a large-scale use of hydrogen in road transport, as soon as renewable energies become more widespread. Its market will expand from large driving range and heavy load vehicles.
Driven by a small number of niche markets and several decades of application research, fuel cell systems (FCS) are gradually reaching maturity, to the point where many players are questioning the ...interest and intensity of its deployment in the transport sector in general. This article aims to shed light on this debate from the road transport perspective. It focuses on the description of the fuel cell vehicle (FCV) in order to understand its assets, limitations and current paths of progress. These vehicles are basically hybrid systems combining a fuel cell and a lithium-ion battery, and different architectures are emerging among manufacturers, who adopt very different levels of hybridization. The main opportunity of Fuel Cell Vehicles is clearly their design versatility based on the decoupling of the choice of the number of Fuel Cell modules and hydrogen tanks. This enables manufacturers to meet various specifications using standard products. Upcoming developments will be in line with the crucial advantage of Fuel Cell Vehicles: intensive use in terms of driving range and load capacity. Over the next few decades, long-distance heavy-duty vehicles and fleets of taxis or delivery vehicles will develop based on range extender or mild hybrid architectures and enable the hydrogen sector to mature the technology from niche markets to a large-scale market.
Acoustic communication is enabled by the evolution of specialised hearing and sound producing organs. In this study, we performed a large-scale macroevolutionary study to understand how both hearing ...and sound production evolved and affected diversification in the insect order Orthoptera, which includes many familiar singing insects, such as crickets, katydids, and grasshoppers. Using phylogenomic data, we firmly establish phylogenetic relationships among the major lineages and divergence time estimates within Orthoptera, as well as the lineage-specific and dynamic patterns of evolution for hearing and sound producing organs. In the suborder Ensifera, we infer that forewing-based stridulation and tibial tympanal ears co-evolved, but in the suborder Caelifera, abdominal tympanal ears first evolved in a non-sexual context, and later co-opted for sexual signalling when sound producing organs evolved. However, we find little evidence that the evolution of hearing and sound producing organs increased diversification rates in those lineages with known acoustic communication.
The forewing venation homologies of magnifica Huang, Schubnel & Nel,
2020
(genus Legendreia) and its claimed bearing on the origin of the taxon Titanopterida are investigated. New data on two Permian ...stem-orthopterans, drewi Beckemeyer,
2011
(genus Loxoedischa) and reticulata Zalessky,
1934
(genus Iasvia), are provided to complement a sample of Permian and Triassic stem-orthopterans relevant to the case. Various forewing venation homology conjectures (HCs) are assembled in sets which themselves are contrasted using the minimum number of transformations they imply as an optimality criterion. None of the sets including the HC favoured in the original description of magnifica convincingly challenge the view that the Titanopterida derived from the Permian tcholmanvissiids, together forming the Pantcholmanvissiida. Moreover, the most parsimonious set involves an HC different from that provided in the original description of magnifica and well supported by morphological evidence. It predicts that the species is not particularly related to the Pantcholmanvissiida. Instead, further comparison reveals that it is a relative of caeliferans (grasshoppers and locusts), and, incidentally, the earliest one.
Identification of a PEMFC fractional order model Taleb, Miassa Amira; Béthoux, Olivier; Godoy, Emmanuel
International journal of hydrogen energy,
01/2017, Letnik:
42, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The present paper addresses the important issue of monitoring the operating state of the Polymer Electrolyte Membrane Fuel Cell systems. The monitoring system takes a model based approach. Its ...originality lies in adopting a fuel cell fractional order impedance model which permits to provide a better insight into the fuel cell physical phenomena without increasing the number of parameters. This article first validates experimentally the accuracy of the suggested model, using a frequency identification method carried out by nonlinear optimization using single fuel cell experimental impedance spectroscopy data. In a second phase, time series identification is achieved using a least square method specifically designed for fractional order models. The latter method is first verified on registered data which represents a basic tool for offline monitoring. Subsequently it is refined as a recursive tool permitting an online monitoring; it is validated on laboratory test bench.
•The problem addressed: Diagnosis of water problems in a fuel cell.•Development of a new PEMFC fractional order model: more compact and accurate.•Model's parameters considered as good indicators of flooding and drying issues.•Identification of the model's parameters using experimental data: EIS (frequential data), time series current/voltage measurements.•Least square method adapted to fractional order models for offline diagnosis, and recursive least square method for online diagnosis.
•Different DC/DC power converter topologies for Fuel Cell systems are presented.•Advantages and drawbacks of the DC/DC power converter topologies are detailed.•Wide-BandGap semiconductors are ...attractive candidates for design of converters.•Wide-BandGap semiconductors improve efficiency and thermal limits of converters.•Different semiconductor technologies are assessed.
Fuel cell-based power sources are attractive devices. Through multi-stack architecture, they offer flexibility, reliability, and efficiency. Keys to accessing the market are simplifying its architecture and each components. These include, among others, the power converter enabling the output voltage regulation. This article focuses on this specific component. The present paper gives a comprehensive overview of the power converter interfaces potentially favorable for the automotive, railways, aircrafts and small stationary domains. First, with respect to the strategic development of a modular design, it defines the specifications of a basic interface. Second, it inventories the best architecture opportunities with respect to these requirements. Based on this study, it fully designs a basic module and points out the outstanding contribution of the new developed silicon carbide switch technology. In conclusion, this review article exhibits the importance of choosing the right power converter architecture and the related technology. In this context it is highlighted that the output power interface can be efficient, compact and modular. In addition, its features enable a thermal compatibility with many ways of integrating this component in the global fuel cell based power source.
Phylogenetic relationships among subgroups of cockroaches and termites are still matters of debate. Their divergence times and major phenotypic transitions during evolution are also not yet settled. ...We addressed these points by combining the first nuclear phylogenomic study of termites and cockroaches with a thorough approach to divergence time analysis, identification of endosymbionts, and reconstruction of ancestral morphological traits and behaviour. Analyses of the phylogenetic relationships within Blattodea robustly confirm previously uncertain hypotheses such as the sister-group relationship between Blaberoidea and remaining Blattodea, and Lamproblatta being the closest relative to the social and wood-feeding Cryptocercus and termites. Consequently, we propose new names for various clades in Blattodea: Cryptocercus + termites = Tutricablattae; Lamproblattidae + Tutricablattae = Kittrickea; and Blattoidea + Corydioidea = Solumblattodea. Our inferred divergence times contradict previous studies by showing that most subgroups of Blattodea evolved in the Cretaceous, reducing the gap between molecular estimates of divergence times and the fossil record. On a phenotypic level, the blattodean ground-plan is for egg packages to be laid directly in a hole while other forms of oviposition, including ovovivipary and vivipary, arose later. Finally, other changes in egg care strategy may have allowed for the adaptation of nest building and other novelties.
A high portion of the earliest known insect fauna is composed of the so-called 'lobeattid insects', whose systematic affinities and role as foliage feeders remain debated. We investigated hundreds of ...samples of a new lobeattid species from the Xiaheyan locality using a combination of photographic techniques, including reflectance transforming imaging, geometric morphometrics, and biomechanics to document its morphology, and infer its phylogenetic position and ecological role.
sp. nov. possessed a sword-shaped ovipositor with valves interlocked by two ball-and-socket mechanisms, lacked jumping hind-legs, and certain wing venation features. This combination of characters unambiguously supports lobeattids as stem relatives of all living Orthoptera (crickets, grasshoppers, katydids). Given the herein presented and other remains, it follows that this group experienced an early diversification and, additionally, occurred in high individual numbers. The ovipositor shape indicates that ground was the preferred substrate for eggs. Visible mouthparts made it possible to assess the efficiency of the mandibular food uptake system in comparison to a wide array of extant species. The new species was likely omnivorous which explains the paucity of external damage on contemporaneous plant foliage.
This paper aims to optimize real-time control for the degraded mode of a fault-tolerant power architecture but not the fault detection and isolation procedure itself. Such power architecture is ...dedicated to electric vehicles in which it performs the three following essential functions: traction, battery charging, and electric-grid assistance. For safety reasons, in the degraded mode, power control is limited to the traction mode. Thus, for a given torque, the proposed innovative strategy uses a novel current/voltage transform that leads to efficient real-time control of the torque. The key idea is to drive the current without a priori restrictions on its waveform, while minimizing Joule losses, i.e., the effective value of the current. It has been validated on a laboratory test bench. The studied system is based on a three-phase open-end-winding synchronous machine powered by an inverter with three full H-bridges. The last section of the paper analyzes the comparison between the classic sinusoidal current waveforms and the proposed sinusoidal current waveforms while operating on the two remaining motor phases. It results in a 14% increase of the torque produced by the permanent-magnet machine under test and a 14% decrease of the global system losses in traction mode. As a result, the new control strategy enhances traction performance in degraded mode and increases electric-vehicle autonomy in a postfailure condition.
During its 320 Myr evolution, dragon- and damselfly (Odonata) wing morphology underwent intense modifications. The resulting diversity prompted comparative analyses focusing on phylogeny. However, ...homoplasy proved to plague wing-related characters. Concurrently, limited benefits were obtained from considering fossil taxa, similarly impacted. Herein, we investigate two aspects particularly affected by convergence, namely the acquisition of vein-like structuring elements derived from regular cross-venation, termed conamina; and the evolution of butter knife wing shape. Conamen implementation is found to be consistently linked with vein curvature sharpening, itself generating potential breaking points. Conamina therefore likely evolved to address wing integrity issues during ever-more-demanding flight performance. Moreover, an existing conamen is likely to trigger the acquisition of further, associated conamina. As for butter knife shape, previously documented in the extinct Archizygoptera and among damselflies, we report a new, 315 Ma occurrence with the rare species
Haidilaozhen cuiae
gen. et sp. nov. (family Haidilaozhenidae fam. nov.), from the Xiaheyan locality (China). The repeated acquisition of butter knife-shaped wing can be related to slow speed flight and, in turn, predator avoidance. In both cases of iterated regularities, the unique ‘network-and-membrane’ wing design proper to insects is found to compose a strong, constraining factor.
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