Energy comparison between different parallel hybrid vehicles architectures

A great boom of hybrid vehicles has taken place on the automotive market in recent years, in particular, all these vehicles are now equipped with a continuously variable transmission (CVT) thanks to the use of a planetary gear train and two electric motor-generators. The benefit provided by this system is the possibility to optimally control the engine velocity from an energy standpoint; in addition, drive comfort is increased thanks to the continuously variable transmission. However, this is obtained at the cost of some amount of electrical losses in the components necessary to realize the above-mentioned structure. This paper aims to evaluate the overall efficiency of this particular power train on different road missions; the same missions will be simulated at the same time for an identical hybrid vehicle equipped with a conventional transmission system. In order to perform an energy analysis of the two architectures, one has to accurately address the main components generating energy losses: it will be thus presented the set of equations from which the mathematical stationary model of the CVT was obtained and how the different electric components and the internal combustion engine were modeled. In addition, a brief description on the CVT optimization logic will be reported, the validity of this process will be then confirmed by comparing the ICE working points deriving from it and those declared by Toyota. Finally, the fuel economy values coming from various road simulations will be compared in order to determine if or which hybrid architecture proves to be the most efficient one

Conceptual design upgrade on hybrid powertrains resulting from electric improvements

Hybrid vehicles have experienced a great boom in recent years thanks to the increasing spread of \u2018parallel\u2019 architectures, often realized by a planetary gear train (hybrid Synergy Drive). At the same time, an enhancement of electrical and electronic components has been experienced; these improvements especially concern reliability and efficiency. Particularly, the possibility of using supercapacitors with increasing storage performances makes possible to manage higher power flows together with a superior efficiency. These innovations may challenge the architecture used nowadays on medium size cars. The hybrid series architecture, which allows the optimal management of the combustion engine, has been disadvantaged until now by the electric powertrain efficiency. In the current scenario, this architecture could benefit from the above-mentioned technology, becoming a competitive alternative to the actual powertrain configurations. The aim of this article is the efficiency analysis, in order to evaluate the operational energy efficiency achievable thanks to this configuration. This analysis will be carried out considering all the possible working conditions of the different powertrains

Solid-state transformers in locomotives fed through AC lines: A review and future developments

One of the most important innovation expectation in railway electrical equipment is the replacement of the on-board transformer with a high power converter. Since the transformer operates at line-frequency (i.e., 50 Hz or 16 2/3 Hz), it represents a critical component from weight point of view and, moreover, it is characterized by quite poor efficiency. High power converters for this application are characterized by a medium frequency inductive coupling and are commonly referred as Power Electronic Transformers (PET), Medium Frequency Topologies or Solid-State Transformers (SST). Many studies were carried out and various prototypes were realized until now, however, the realization of such a system has some difficulties, mainly related to the high input voltage (i.e., 25 kV for 50 Hz lines and 15 kV for 16 2/3 Hz lines) and the limited performance of available power electronic switches. The aim of this study is to present a survey on the main solutions proposed in the technical literature and, analyzing pros and cons of these studies, to introduce new possible circuit topologies for this application

Soft-switching cells for Modular Multilevel Converters for efficient grid integration of renewable sources

The Modular Multilevel Converter (MMC) concept is a modern energy conversion structure that stands out for a number of interesting features that opens wide application chances in Power Systems, for example for efficient grid integration of renewable sources. In these high-voltage, high-power application fields, a high efficiency is mandatory. In this regard, an interesting and promising development opportunity could be to make soft-switching the elementary converters of the submodules (cells), half H-bridges or full H-bridges, obtaining at the same time the advantage of increasing the switching frequency. The-Active Resonant Commutated Pole Converter (ARCP) or the Auxiliary Quasi Resonant DC-link Inverter (AQRDCL) soft-switching topologies appear adequate for this purpose. This paper is dedicated to examining these development possibilities

Turbocompound power unit modelling for a supercapacitor-based series hybrid vehicle application

In this paper, starting from the measurements available for a 2000 cm3 turbocharged diesel engine, an analytical model of the turbocharger is proposed and validated. The model is then used to extrapolate the efficiency of a power unit with a diesel engine combined with a turbocompound system. The obtained efficiency map is used to evaluate the fuel economy of a supercapacitor-based series hybrid vehicle equipped with the turbocompound power unit. The turbocompound model, in accordance with the studies available in the technical literature, shows that the advantages (in terms of efficiency increase) are significant at high loads. For this reason, turbocompound introduction allows a significant efficiency improvement in a series hybrid vehicle, where the engine always works at high-load. The fuel economy of the proposed vehicle is compared with other hybrid and conventional vehicle configurations

Computational analysis of transport in three-dimensional heterogeneous materials: An OpenFOAM®-based simulation framework

Porous and heterogeneous materials are found in many applications from composites, membranes, chemical reactors, and other engineered materials to biological matter and natural subsurface structures. In this work we propose an integrated approach to generate, study and upscale transport equations in random and periodic porous structures. The geometry generation is based on random algorithms or ballistic deposition. In particular, a new algorithm is proposed to generate random packings of ellipsoids with random orientation and tunable porosity and connectivity. The porous structure is then meshed using locally refined Cartesian-based or unstructured strategies. Transport equations are thus solved in a finite-volume formulation with quasi-periodic boundary conditions to simplify the upscaling problem by solving simple closure problems consistent with the classical theory of homogenisation for linear advection–diffusion–reaction operators. Existing simulation codes are extended with novel developments and integrated to produce a fully open-source simulation pipeline. A showcase of a few interesting three-dimensional applications of these computational approaches is then presented. Firstly, convergence properties and the transport and dispersion properties of a periodic arrangement of spheres are studied. Then, heat transfer problems are considered in a pipe with layers of deposited particles of different heights, and in heterogeneous anisotropic materials

Choosing the optimal dose in sublingual immunotherapy: Rationale for the 300 index of reactivity dose

Sublingual immunotherapy (SLIT) is an effective and well-tolerated method of treating allergic respiratory diseases associated with seasonal and perennial allergens. In contrast to the subcutaneous route, SLIT requires a much greater amount of antigen to achieve a clinical effect. Many studies have shown that SLIT involves a dose-response relationship, and therefore it is important to use a proven clinically effective dose from the onset of treatment, because low doses are ineffective and very high doses may increase the risk of side effects. A well-defined standardization of allergen content is also crucial to ensure consistent quality, potency and appropriate immunomodulatory action of the SLIT product. Several methods of measuring antigenicity are used by manufacturers of SLIT products, including the index of reactivity (IR), standardized quality tablet unit, and bioequivalent allergy unit. A large body of evidence has established the 300 IR dose of SLIT as offering optimal efficacy and tolerability for allergic rhinitis due to grass and birch pollen and HDM, and HDM-induced moderate, persistent allergic asthma. The 300 IR dose also offers consistency of dosing across a variety of different allergens, and is associated with higher rates of adherence and patient satisfaction. Studies in patients with grass pollen allergies showed that the 300 IR dose has a rapid onset of action, is effective in both adults and children in the short term and, when administered pre-coseasonally in the long term, and maintains the clinical benefit, even after cessation of treatment. In patients with HDM-associated AR and/or asthma, the 300 IR dose also demonstrated significant improvements in symptoms and quality of life, and significantly decreased use of symptomatic medication. The 300 IR dose is well tolerated, with adverse events generally being of mild or moderate severity, declining in frequency and severity over time and in the subsequent courses. We discuss herein the most important factors that affect the selection of the optimal dose of SLIT with natural allergens, and review the rationale and evidence supporting the use of the 300 IR dose

Allergen immunotherapy in asthma; what is new?

The use and role of allergen immunotherapy (AIT) in asthma is still a matter of debate, and no definite recommendation about this is made in guidelines, both for the subcutaneous and sublingual routes. This is essentially due to the fact that most controlled randomised trials were not specifically designed for asthma, and that objective measures of pulmonary function were only occasionally considered. Nonetheless, in many trials, favourable results in asthma (symptoms, medication usage, bronchial reactivity) were consistently reported. There are also several meta analyses in favour of AIT, although their validity is limited by a relevant methodological heterogeneity. In addition to the crude clinical effect, a disease modifying action of AIT (prevention of asthma onset and long-lasting effects) have been reported. The safety is an important aspect to consider in asthma. Fatalities were rare: In Europe no fatality was reported in the last three decades, as in the United States in the last 4 years. Based on previous surveys, and common sense, uncontrolled asthma is still recognized as the most important risk factor for severe adverse events. On the contrary, there is no evidence that AIT can worsen or induce asthma. According to the available evidence, AIT can be safely used as add-on treatment when asthma is associated with rhinitis (a frequent condition), provided that asthma is adequately controlled by pharmacotherapy. AIT cannot be recommended or suggested as single therapy. When asthma is the unique manifestation of respiratory allergy, its use should be evaluated case by case

Extracellular release of the ‘differentiation enhancing factor’, a HMG1 protein type, is an early step in murine erythroleukemia cell differentiation

AbstractDifferentiation enhancing factor (DEF) is a 29 kDa protein expressed in murine erythroleukemia (MEL) cells and active in promoting a significant increase in the rate of hexamethylenebisacetamide induced differentiation of these cells. The factor was recently shown to possess an amino acid sequence identical to that reported for one of the HMG1 proteins, designated as ‘amphoterin’ on the basis of its highly dipolar sequence. In the present study, we have expressed DEF cDNA in an E. coli strain and found that the recombinant protein has functional properties identical to those observed with native DEF. Furthermore, we demonstrate that, following MEL cell stimulation with the chemical inducer, DEF is secreted in large amounts in the extracellular medium. In fact, the N-terminal sequence and the partial amino acid sequence of tryptic peptides from the secreted protein correspond to those of DEF isolated from the soluble fraction of resting MEL cells. These results are indicative for an extracellular localization as the site of action of DEF and suggest a novel function for proteins belonging to the HMG1 family. Finally, the early decay of DEF mRNA, in chemical induced MEL cells, support the hypothesis that the involvement of the enhancing factor occurs and is completed in the early phases of cell differentiation