An investigation of hybrid energy storage system in multi-speed electric vehicle

© 2017 Elsevier Ltd Thanks to the lower overall emission of Electric Vehicles, the promising transportation has attracted numerous attentions from industry and academy. However, as a consequence of lower energy density in widely adopted electrochemical energy source-battery, the driving range per charge presents a major barrier for electric vehicle's large-scale commercialization. Additionally, the limited battery life and extra costs associated with its replacement are other negative factors that hinder the development of electric vehicle. Currently, the one-speed gearbox is dominant in electric vehicles' market though it is only a trade-off between manufacturing cost and vehicle performance. Therefore, multi-speed electrified powertrains have been proposed and investigated in this paper to pursue the improvement of energy efficiency and dynamic performance without increasing battery size. In addition, supercapacitor, as the supplementary to battery, is combined with multi-speed transmissions to improve driving range and battery life. The combination of two advanced technologies are investigated in both B and E-class electric vehicle. Results demonstrate that considerable benefits attained for both small and large passenger vehicles through the application of multi-speed transmissions. The effectiveness of hybrid energy storage system in protecting battery from damage is verified. The relationship of hybrid energy storage system and multi-speed transmission is reported

Development of continuously variable transmission and multi-speed dual-clutch transmission for pure electric vehicle

© 2018, © The Author(s) 2018. Pure electric vehicles, as a promising alternative to conventional fossil fuel–powered passenger vehicles, provide outstanding overall energy-utilizing efficiency by omitting the internal combustion engine. However, because of lower energy density in battery energy storage, the driving range per charge is limited by this electrochemical power source, leading to a so-called range phobia and presenting a major barrier for large-scale commercialization. The widely adopted single-reduction gear in pure electric vehicles typically do not achieve the diverse range of functional needs that are present in multi-speed conventional vehicles, most notably acceleration performance and top speed requirements. Consequently, special-designed multi-speed pure electric vehicle–powertrains have been compared and investigated for these applications in this article. Through the optimizing of multiple gear ratios and creating special shifting strategies, a more diverse range of functional needs is realized without increasing the practical size of the electric motor and battery. This article investigates the performance improvements of pure electric vehicle realized through utilization of multi-speed dual-clutch transmissions and continuously variable transmissions. Results reveal that there can be significant benefits attained for pure electric vehicles through multi-speed transmissions. Simulation results shows that continuously variable transmission and two-speed transmission are the two most promising transmissions for pure electric vehicle in different classes, respectively

Synthesis, crystal structure, magnetic and electronic properties of the caesium-based transition metal halide Cs<inf>3</inf>Fe<inf>2</inf>Br<inf>9</inf>

The diversity of halide materials related to important solar energy systems such as CsPbX3 (X = Cl, Br, I) is explored by introducing the transition metal element Fe. In particular a new compound, Cs3Fe2Br9 (space group P6_3/mmc with a = 7.5427(8) and c = 18.5849(13) {\AA}), has been synthesized and found to contain 0D face-sharing Fe2Br9 octahedral dimers. Unlike its isomorph, Cs3Bi2I9, it is black in color, has a low optical bandgap of 1.65 eV and exhibits antiferromagnetic behavior below TN = 13 K. Density functional theory calculations shed further light on these properties and also predict that the material should have anisotropic transport characteristics

A novel shift control concept for multi-speed electric vehicles

© 2018 Elsevier Ltd This paper proposes a novel synchronizer ‘Harpoon-Shift’ aiming at improving the comfort and efficiency of gearbox, meanwhile, simplifying the shifting control strategy for multi-speed electric vehicles. It will overcome one of the biggest shortcomings of traditional synchronizer system with frictional cone clutch. Experiment is established to investigate the torque and speed responses during the engagement of gears pairs. Then, based on previous testing results, the relationship of the peak torque and minimum speed difference to implement gear shifting with various spring coefficients is investigated. In addition, a mathematical model of the Harpoon-Shift system is developed to simulate the engagement process. The simulation results of system transient responses are validated against the data measured on testing rig. The model is then improved to study the impact of the rotating inertia, speed and speed difference on the torsional vibration and required time of engagement. Both of the simulation and experimental results show the significant improvement of proposed synchronizer to conventional cone clutch synchronizer

Pulmonary Embolism Incidence and Fatality Trends in Chinese Hospitals from 1997 to 2008: A Multicenter Registration Study

BACKGROUND: There has not been sufficient evidence to support the Asians being less susceptible to pulmonary embolism (PE) than other ethnicities, because the prevalence of PE/deep venous thrombosis (DVT) in different racial and ethnic groups has not been carefully studied until recently except in Caucasians. To test the hypothesis that the Chinese population has a lower risk for PE, this study comprehensively assessed the hospital-based incidence and case fatality rates for PE during the 1997-2008 in China. METHODS: A registration study of patients with suspected PE syndromes admitted to 60 level-3 hospitals involved in the National Cooperative Project for the Prevention and Treatment of Venous Thromboembolism (NCPPT) was conducted from January 1997 to December 2008. The only exclusion criterion was an age of less than 18 years. Helical computed tomography scan, ventilation-perfusion lung scintigraphy or pulmonary angiography was carried out before or after hospitalization. All images were reviewed and evaluated independently by two specialists. RESULTS: A total of 18,206 patients were confirmed with PE from 16,972,182 hospital admissions. The annual incidence was 0.1% (95% CI: 0.1% to 0.2%). The overall incidence of PE in male patients (0.2%, 95% CI: 0.1% to 0.3%) was higher than that in female patients (0.1% and 95% CI: 0.0% to 0.1%). An increasing incidence gradient for PE was noticed from Southern to Northern China. In addition, the case fatality rate was apparently decreasing: 25.1% (95% CI: 16.2% to 36.9%) in 1997 to 8.7% (95% CI: 3.5% to 15.8%) in 2008. CONCLUSIONS: Our findings suggest the relatively stable PE incidence and decreasing fatality trends in Chinese hospitals may be partially attributable to the implementation of the NCCPT and suggest the government should reevaluate the severity of PE so that health resources for the prevention, diagnosis and treatment of PE could be used to their fullest

Blue laser directed energy deposition of aluminum with synchronously enhanced efficiency and quality

Directed energy deposition (DED) of aluminum with infrared lasers faces many processing issues, e.g., poor formability, pore formation, high reflectivity, all lowering the productivity. In this paper, we developed and applied a 2 kW high-power (450 nm) blue laser directed energy deposition (BL-DED) of a nano-TiB2 decorated AlSi10Mg composite. The single-track experiment reveals that the required power density of blue laser to form fully melted track is lower than that of an infrared laser (1060 nm). Under the laser power of 900 W with a scanning speed of 4 mm/s, the width and depth of molten pool is approximately 2500 µm and 350 µm respectively with blue laser, while the powders are not fully melted with infrared laser, owing to aluminum's higher absorption at blue laser wavelengths. The area fraction of equiaxed grains accounts for as high as 63% at 4 mm/s. To the best of our knowledge, this result is the highest area fraction of equiaxed grains in a single-track molten pool of DED process. Such a high fraction is mainly due to the low thermal gradient (8 × 105 K/m) of the flat-top blue laser and the refining effect of nano TiB2 particles. Our work demonstrates that high-power blue laser has enhanced both efficiency and build quality compared to DED of aluminum alloys and composites using an infrared laser, which also promises to help process other high-reflectivity materials like copper alloys

Regional and local emissions in red river delta, Northern Vietnam

Fine (PM2.2) and coarse (PM2.2–10) particles concurrently collected in urban (Hanoi) and rural (Lucnam) areas were analyzed for ionic and elemental compositions to provide input for PMF receptor modeling of emission sources in the Red River Delta (RRD), a key economic development region in Vietnam. Long-range transport (LRT) aerosol, coal fly ash from major coal-fired plants in RRD, and marine aerosols are regional sources, which explain the minor variability of the mass concentrations of fine particles across the region. Local sources include soil/resuspended road dust, local coal fly ash, and biomass burning. Soil/resuspended road dust is the largest source component of coarse particles at the two sites. It is more abundant in Hanoi than in Lucnam reflecting the urban–rural contrast in traffic and construction works. Receptor models reveal the incorporation of secondary sulfate, nitrate, and ammonium into the various primary particles, i.e., soot, minerals, soil organic matter, and sea salt. Soot particles from LRT carry the largest amounts of sulfate and ammonium mass concentrations measured at the two sites. Based on receptor models, the yields and possible chemical forms of secondary sulfate, nitrate, and ammonium in different types of primary particles can be inferred

Questionnaire study to gain an insight into the manufacturing and fitting process of artificial eyes in children: an ocularist perspective

Purpose To gain an insight into the manufacturing and fitting of artificial eyes in children and potential improvements to the process. Method An online qualitative survey was distributed to 39 ocularists/prosthetists in Europe and Canada. Participants were recruited through purposive sampling, specifically maximum variation sampling from the researcher’s contacts and an online search. Results The findings highlighted the current impression technique as being the most difficult yet most important part of the current process for both the ocularist and child patient. Negatively affecting obtaining a good impression, the child patients distress can be reduced by their parents by providing encouragement, reassurance, practicing the insertion and removal of the artificial eye and being matter of fact. Whilst improvements to the current process provided mixed views, the incorporation of current technology was perceived as not being able to meet the requirements to produce aesthetically pleasing artificial eyes. Conclusion The current artificial eye process can be seen as an interaction with its success being dependent on the child patient’s acceptance and adjustment which is dependent on the factors associated to the process. Investigation into the needs of the patient and whether technology can improve the process are the next steps in its advancement