scholarly journals A Review of Hybrid Electric Architectures in Construction, Handling and Agriculture Machines

2021 ◽  
Author(s):  
Francesco Mocera ◽  
Aurelio Somà
Keyword(s):  
Pollutant Emissions ◽  
Valuable Alternative ◽  
Specific Field ◽  
Current State ◽  
Long Time ◽  
Hybrid Electric ◽  
Application Fields ◽  
Work Done ◽  
Aftertreatment Systems ◽  
Alternative Solutions

Recent regulations on pollutant emissions have pushed working machines manufacturers towards research and development efforts to meet the strict limits imposed. For a long time, the use of gas aftertreatment systems have been the most widely accepted solution to reduce the amount of pollutants produced per unit of work done. However, lower emissions limits lead to larger systems and consequently higher difficulties in vehicle integration. Thus, alternative solutions have been studied in the last years to solve the emissions problem using wisely the on-board space. Hybrid electric technologies represent a valuable alternative in this direction. In this work, a review of the current state of the art in the adoption of hybrid and electric technologies on working vehicles is proposed. Due to the high amount of application fields and concepts for special applications, the analysis focused on the three major fields which however includes most of the working machines: Construction, Handling and Agriculture. This work highlights how the requirements of each specific field, strongly affects the design of an optimal hybrid electric architectures.

Comparative analysis on the effects of diesel particulate filter and selective catalytic reduction systems on a wide spectrum of chemical species emissions

2018 ◽  
Author(s):  
Z. Gerald Liu ◽  
Devin R. Berg ◽  
Thaddeus A. Swor ◽  
James J. Schauer‡
Keyword(s):  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Diesel Particulate Filter ◽  
Catalytic Reduction ◽  
Wide Spectrum ◽  
Chemical Species ◽  
Pollutant Emissions ◽  
Particulate Filter ◽  
Diesel Particulate ◽  
Aftertreatment Systems

Two methods, diesel particulate filter (DPF) and selective catalytic reduction (SCR) systems, for controlling diesel emissions have become widely used, either independently or together, for meeting increasingly stringent emissions regulations world-wide. Each of these systems is designed for the reduction of primary pollutant emissions including particulate matter (PM) for the DPF and nitrogen oxides (NOx) for the SCR. However, there have been growing concerns regarding the secondary reactions that these aftertreatment systems may promote involving unregulated species emissions. This study was performed to gain an understanding of the effects that these aftertreatment systems may have on the emission levels of a wide spectrum of chemical species found in diesel engine exhaust. Samples were extracted using a source dilution sampling system designed to collect exhaust samples representative of real-world emissions. Testing was conducted on a heavy-duty diesel engine with no aftertreatment devices to establish a baseline measurement and also on the same engine equipped first with a DPF system and then a SCR system. Each of the samples was analyzed for a wide variety of chemical species, including elemental and organic carbon, metals, ions, n-alkanes, aldehydes, and polycyclic aromatic hydrocarbons, in addition to the primary pollutants, due to the potential risks they pose to the environment and public health. The results show that the DPF and SCR systems were capable of substantially reducing PM and NOx emissions, respectively. Further, each of the systems significantly reduced the emission levels of the unregulated chemical species, while the notable formation of new chemical species was not observed. It is expected that a combination of the two systems in some future engine applications would reduce both primary and secondary emissions significantly.

scholarly journals Multi-Task Optimization and Multi-Task Evolutionary Computation in the Past Five Years: A Brief Review

Mathematics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 864
Author(s):  
Qingzheng Xu ◽  
Na Wang ◽  
Lei Wang ◽  
Wei Li ◽  
Qian Sun
Keyword(s):  
Evolutionary Computation ◽  
Explicit Knowledge ◽  
Optimization Problems ◽  
Effective Means ◽  
Typical Application ◽  
The Past ◽  
Current State ◽  
Evolution Algorithms ◽  
Application Fields

Traditional evolution algorithms tend to start the search from scratch. However, real-world problems seldom exist in isolation and humans effectively manage and execute multiple tasks at the same time. Inspired by this concept, the paradigm of multi-task evolutionary computation (MTEC) has recently emerged as an effective means of facilitating implicit or explicit knowledge transfer across optimization tasks, thereby potentially accelerating convergence and improving the quality of solutions for multi-task optimization problems. An increasing number of works have thus been proposed since 2016. The authors collect the abundant specialized literature related to this novel optimization paradigm that was published in the past five years. The quantity of papers, the nationality of authors, and the important professional publications are analyzed by a statistical method. As a survey on state-of-the-art of research on this topic, this review article covers basic concepts, theoretical foundation, basic implementation approaches of MTEC, related extension issues of MTEC, and typical application fields in science and engineering. In particular, several approaches of chromosome encoding and decoding, intro-population reproduction, inter-population reproduction, and evaluation and selection are reviewed when developing an effective MTEC algorithm. A number of open challenges to date, along with promising directions that can be undertaken to help move it forward in the future, are also discussed according to the current state. The principal purpose is to provide a comprehensive review and examination of MTEC for researchers in this community, as well as promote more practitioners working in the related fields to be involved in this fascinating territory.

scholarly journals Detecting hotspots of atmosphere–vegetation interaction via slowing down – Part 1: A stochastic approach

2013 ◽  
Vol 4 (1) ◽  
pp. 63-78 ◽  
Author(s):  
S. Bathiany ◽  
M. Claussen ◽  
K. Fraedrich
Keyword(s):  
Climate Models ◽  
Stochastic Approach ◽  
General Context ◽  
Grid Cells ◽  
Climate System Model ◽  
Local Loss ◽  
Slowing Down ◽  
Current State ◽  
Long Time ◽  
Sudden Transition

Abstract. An analysis of so-called early warning signals (EWS) is proposed to identify the spatial origin of a sudden transition that results from a loss in stability of a current state. EWS, such as rising variance and autocorrelation, can be indicators of an increased relaxation time (slowing down). One particular problem of EWS-based predictions is the requirement of sufficiently long time series. Spatial EWS have been suggested to alleviate this problem by combining different observations from the same time. However, the benefit of EWS has only been shown in idealised systems of predefined spatial extent. In a more general context like a complex climate system model, the critical subsystem that exhibits a loss in stability (hotspot) and the critical mode of the transition may be unknown. In this study we document this problem with a simple stochastic model of atmosphere–vegetation interaction where EWS at individual grid cells are not always detectable before a vegetation collapse as the local loss in stability can be small. However, we suggest that EWS can be applied as a diagnostic tool to find the hotspot of a sudden transition and to distinguish this hotspot from regions experiencing an induced tipping. For this purpose we present a scheme which identifies a hotspot as a certain combination of grid cells which maximise an EWS. The method can provide information on the causality of sudden transitions and may help to improve the knowledge on the susceptibility of climate models and other systems.

scholarly journals 20 years of African Neuroscience: Waking a sleeping giant

2020 ◽  
Author(s):  
MB Maina ◽  
U Ahmad ◽  
HA Ibrahim ◽  
SK Hamidu ◽  
FE Nasr ◽  
...  
Keyword(s):  
Brain Research ◽  
Demographic Data ◽  
Model Systems ◽  
Depth Information ◽  
Current State ◽  
Neuroscience Research ◽  
Global North ◽  
New Policies ◽  
The Uk ◽  
Work Done

Understanding the function and dysfunction of the brain remains one of the key challenges of our time. However, an overwhelming majority of brain research is carried out in the Global North, by a minority of well-funded and intimately interconnected labs. In contrast, with an estimated one neuroscientist per million people in Africa, news about neuroscience research from the Global South remains sparse. Clearly, devising new policies to boost Africa’s neuroscience landscape is imperative. However, the policy must be based on accurate data, which is largely lacking. Such data must reflect the extreme heterogeneity of research outputs across the continent’s 54 countries distributed over an area larger than USA, Europe and China combined. Here, we analysed all of Africa’s Neuroscience output over the past 21 years. Uniquely, we individually verified in each of 12,326 publications that the work was indeed performed in Africa and led by African-based researchers. This step is critical: previous estimates grossly inflated figures, because many of Africa’s high-visibility publications are in fact the result of internationally led collaborations, with most work done outside of Africa. The remaining number of African-led Neuroscience publications was 5,219, on average only ~5 per country and year. From here, we extracted metrics such as the journal and citations, as well as detailed information on funding, international collaborations and the techniques and model systems used. We link these metrics to demographic data and indicators of mobility and economy. For reference, we also extracted the same metrics from 220 randomly selected publications each from the UK, USA, Australia, Japan and Brazil. Our unique dataset allows us to gain accurate and in-depth information on the current state of African Neuroscience research, and to put it into a global context. This in turn allows us to make actionable recommendations on how African research might best be supported in the future.

scholarly journals Enabling the potential of hybrid electric propulsion through lean-burn-combustion turbofans

2021 ◽  
Vol 5 ◽  
pp. 164-176
Author(s):  
Stavros Vouros ◽  
Mavroudis Kavvalos ◽  
Smruti Sahoo ◽  
Konstantinos Kyprianidis
Keyword(s):  
Electric Propulsion ◽  
Direct Injection ◽  
Operating Cost ◽  
Pollutant Emissions ◽  
Civil Aviation ◽  
Lean Burn ◽  
Lean Direct Injection ◽  
Direct Operating Cost ◽  
Hybrid Electric ◽  
The Impact

Hybrid-electric propulsion has emerged as a promising technology to mitigate the adverse environmental impact of civil aviation. Boosting conventional gas turbines with electric power improves mission performance and operability. In this work the impact of electrification on pollutant emissions and direct operating cost of geared turbofan configurations is evaluated for an 150-passenger aircraft. A baseline two-and-a-half-shaft geared turbofan, representative of year 2035 entry-into-service technology, is employed. Parallel hybridization is implemented through coupling a battery-powered electric motor to the engine low-speed shaft. A multi-disciplinary design space exploration framework is employed comprising modelling methods for multi-point engine design, aircraft sizing, performance and pollutant emissions, mission and economic analysis. A probabilistic approach is developed considering uncertainties in the evaluation of direct operating cost. Sensitivities to electrical power system technology levels, as well as fuel price and emissions taxation are quantified at different time-frames. The benefits of lean direct injection are explored along short-, medium-, and long-range missions, demonstrating 32% NO<italic><sub>x</sub></italic> savings compared to traditional rich-burn, quick-mix, lean-burn technologies in short-range operations. The impact of electrification on the enhancement of lean direct injection benefits is investigated. For hybrid-electric powerplants, the take-off-to-cruise turbine entry temperature ratio is 2.5% lower than the baseline, extending the corresponding NO<italic><sub>x</sub></italic> reductions to the level of 46% in short-range missions. This work sheds light on the environmental and economic potential and limitations of a hybrid-electric propulsion concept towards a greener and sustainable civil aviation.

Legislative Politics

2017 ◽  
Author(s):  
Olivier Costa
Keyword(s):  
Comparative Literature ◽  
Political Regime ◽  
Legislative Politics ◽  
New Work ◽  
Legislative Studies ◽  
Current State ◽  
French Case ◽  
Long Time ◽  
French Political Science ◽  
Over Time

This chapter proposes an assessment of the state of the study of legislative politics in France. It starts with a review of how the study of legislative politics has developed comparatively over time and identifies the major current debates in the comparative literature. Then it turns to the French case, explaining its weaknesses and peculiarities, and assessing the current state of legislative studies in France. We see that, for a long time, legislative studies were rare in the landscape of French political science. Things, though, have evolved since the end of the 1990s, when there was a renewed scholarly interest in central institutions and actors of the French political regime as well as the emergence of new work that was better connected with the methods, theories, and topics of mainstream legislative studies. Finally, we underline some dimensions of the agenda for the future study of legislative politics in France.

Strengthening and performance assessing historical cinema hall balcony according to new Turkish Earthquake Code

2021 ◽  
Vol 7 (1) ◽  
pp. 27
Author(s):  
Memduh Karalar ◽  
Murat Çavuşli
Keyword(s):  
Performance Analysis ◽  
Three Dimensional ◽  
Performance Evaluations ◽  
Current Status ◽  
Current State ◽  
Long Time ◽  
History Of ◽  
And Performance ◽  
Special Computer Program ◽  
Study Performance

Strengthening historical buildings and evaluating their performances make great contributions to both the history of the country and the tourism of the country. In this study, performance analysis and evaluations of the historical cinema hall balcony, which was built in 1933 by a French company and served to Zonguldak province for a long time, are presented in detail. This cinema hall was frequently used by local people between 1933 and 1999 and hosted many Yeşilçam movies. Firstly, examinations were performed in the historical cinema hall and the areas (columns, beams and floors) that were damaged in time were identified. According to the obtained information, it was determined that there were significant damages in the carrier system of the building and there were visible cracks and damages in the columns of the cinema hall. It was also observed that explosions occurred in one of the main carrier columns of the balcony. After the core samples taken from the balcony were tested in the laboratory, the current status of the carrier elements and reinforcements were determined with the help of an x-ray rebar scanner. After all these processes, the structure was modeled as three dimensional (3D) using a special computer program and performance evaluations were performed regarding the current state of the structure. As a result of the performance evaluation, it was determined that the balcony of the historical cinema hall could not survive anymore and would collapse over time. It was concluded that there were great damages especially on the balcony columns and a reinforcement should be made on a total of 6 columns. Strengthening was made to 4 different main columns and a performance analysis was performed again in strengthened structure. After strengthening, it was understood that the columns of the balcony of the cinema hall could survive for a long time.

Current state of heart surgery in relation to some views on modern surgical science

1927 ◽  
Vol 23 (3) ◽  
pp. 340-347
Author(s):  
V. L. Bogolyubov
Keyword(s):  
Internal Medicine ◽  
Gastrointestinal Tract ◽  
Biliary Tract ◽  
Heart Surgery ◽  
Surgical Intervention ◽  
Progressive Movement ◽  
Current State ◽  
Long Time ◽  
Sphere Of Influence

Modern surgery is taking over more and more organs, recapturing more and more areas of internal medicine. We see that in its great progressive movement surgery gradually involves within its sphere of influence a whole range of diseases that previously belonged exclusively to the sphere of internal medicine, such as some diseases of the gastrointestinal tract, biliary tract, lungs, etc. We see that even those organs, which until so recently were considered inaccessible to the art of the surgeon, are beginning to be subject to surgical intervention. Such last inviolable organ, on which the hand of the surgeon has not encroached for a long time, is the heart.

Influence of Low Ambient Temperatures on the Exhaust Gas and Deposit Composition of Gasoline Engines

2021 ◽  
pp. 1-11
Author(s):  
Dominik Appel ◽  
Fabian P. Hagen ◽  
Uwe Wagner ◽  
Thomas Koch ◽  
Henning Bockhorn ◽  
...  
Keyword(s):  
Internal Combustion Engines ◽  
Gasoline Engine ◽  
Cold Start ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Ex Situ ◽  
Exhaust Gas ◽  
Gasoline Engines ◽  
Ambient Temperatures ◽  
Aftertreatment Systems

Abstract To comply with future emission regulations for internal combustion engines, system-related cold-start conditions in short-distance traffic constitute a particular challenge. Under these conditions, pollutant emissions are seriously increased due to internal engine effects and unfavorable operating conditions of the exhaust aftertreatment systems. As a secondary effect, the composition of the exhaust gases has a considerable influence on the deposition of aerosols via different deposition mechanisms and on fouling processes of exhaust gas-carrying components. Also, the performance of exhaust gas aftertreatment systems may be affected disadvantageously. In this study, the exhaust gas and deposit composition of a turbocharged three-cylinder gasoline engine is examined in-situ upstream of the catalytic converter at ambient and engine starting temperatures of -22 °C to 23 °C using a Fourier-transform infrared spectrometer and a particle spectrometer. For the cold start investigation, a modern gasoline engine with series engine periphery is used. In particular, the investigation of the behavior of deposits in the exhaust system of gasoline engines during cold start under dynamic driving conditions represents an extraordinary challenge due to an average lower soot concentration in the exhaust gas compared to diesel engines and so far, has not been examined in this form. A novel sampling method allows ex-situ analysis of formed deposits during a single driving cycle. Both, particle number concentration and the deposition rate are higher in the testing procedure of Real Driving Emissions (RDE) than in the inner-city part of the Worldwide harmonized Light vehicles Test Cycle (WLTC). In addition, reduced ambient temperatures increase the amount of deposits, which consist predominantly of soot and to a minor fraction of volatile compounds. Although the primary particle size distributions of the deposited soot particles do not change when boundary conditions change, the degree of graphitization within the particles increases with increasing exhaust gas temperature.

scholarly journals Synergy Effects in Electric and Hybrid Electric Aircraft

Aerospace ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 32 ◽  
Author(s):  
Teresa Donateo ◽  
Claudia Lucia De Pascalis ◽  
Antonio Ficarella
Keyword(s):  
Power System ◽  
Unmanned Aerial Vehicle ◽  
Weight Ratio ◽  
Electric Power System ◽  
Pollutant Emissions ◽  
Synergic Effect ◽  
Vtol Uav ◽  
Aerial Vehicle ◽  
Hybrid Electric ◽  
Different Levels

The interest in electric and hybrid electric power system has been increasing, in recent times, due to the benefits of this technology, such as high power-to-weight ratio, reliability, compactness, quietness, and, above all, elimination of local pollutant emissions. One of the key factors of these technologies is the possibility to exploit the synergy between powertrain, structure, and mission. This investigation addresses this topic by applying multi-objective optimization to two test cases — a fixed-wing, tail-sitter, Vertical Take-off and Landing Unmanned Aerial Vehicle (VTOL-UAV), and a Medium-Altitude Long-Endurance Unmanned Aerial Vehicle (MALE-UAV). Cruise time and payload weight were selected as goals for the first optimization problem, while fuel consumption and electric endurance were selected for the second one. The optimizations were performed with Non-dominated Sorting Genetic Algorithm-II (NSGA-II) and S-Metric Selection Evolutionary Multiobjective Algorithm (SMS-EMOA), by taking several constraints into account. The VTOL-UAV optimization was performed, at different levels (structure only, power system only, structure and power system together). To better underline the synergic effect of electrification, the potential benefit of structural integration and multi-functionalization was also addressed. The optimization of the MALE-UAV was performed at two different levels (power system only, power system, and mission profile together), to explore the synergic effect of hybridization. Results showed that large improvements could be obtained, either in the first test case when, both, the powertrain design and the aircraft structure were considered, and in the optimization of the hybrid electric UAV, where the optimization of the aircraft flight path gave a strong contribution to the overall performances.

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