Comparison of frontal crash compatibility metrics between battery-electric and internal-combustion-engine passenger vehicles

OBJECTIVE

The objective of this study was to determine if there are any emerging issues related to battery-electric vehicles' (BEVs') geometry, force distribution, and extra weight that may make them more aggressive partners in front-to-front crashes through comparisons of stiffness metrics derived from crash tests.

METHODS

We examined load cell wall data from the National Highway Traffic Safety Administration's (NHTSA's) New Car Assessment Program full-width frontal crash test at 56 km/h. Fourteen BEVs, ranging in class from small cars to large SUVs, were compared with 92 internal-combustion-engine (ICE) vehicles, ranging in class from small cars to midsize pickups. We selected vehicles based on the test results available in the NHTSA Vehicle Crash Test Database, and there were no tests of battery-electric (BE) pickups. Data included load-cell-wall force-time histories and longitudinal vehicle acceleration from the body structure. We constructed force-displacement diagrams and calculated static, dynamic, energy-equivalent, and initial front-end-stiffness metrics from load cell wall forces, vehicle acceleration, and static front-end crush measurements for each vehicle. Linear regression models were applied to the metrics for comparison between powertrains.

RESULTS

BE cars and BE SUVs weighed more than their ICE counterparts, on average 369 kg and 286 kg more, respectively. Initial (200 mm and 400 mm), energy-equivalent and dynamic front-end-stiffness metrics, average height of force, and individual maximum forces, when compared with vehicle shadow, were not statistically different between powertrains. Static stiffness (p = 0.04) and initial stiffness (300 mm; p = 0.05) decreased for BEVs with greater shadow and increased with greater shadow for ICE vehicles. When controlling for vehicle shadow, dynamic crush was greater (p = 0.01), the percentage of center force was lower (p < 0.001), and maximum peak force was higher (p = 0.01) for BEVs compared with ICE vehicles. For the Kia Niro BEV and ICE pair, the 329 kg heavier BEV had a 165 mm longer crush distance, which resulted in lower forces and stiffness metrics compared with the traditional ICE counterpart.

CONCLUSION

Overall, this study indicates that current BEVs are not excessively aggressive in terms of stiffness metrics for frontal crash compatibility compared with ICE vehicles.

Predicting Design Solutions with Scenarios Considering the Quality of Materials and Products Based on a Life Cycle Assessment (LCA)

The advancement of quality and environmentally sustainable materials and products made from them has improved significantly over the last few years. However, a research gap is the lack of a developed model that allows for the simultaneous analysis of quality and environmental criteria in the life-cycle assessment (LCA) for the selection of materials in newly designed products. Therefore, the objective of the research was to develop a model that supports the prediction of the environmental impact and expected quality of materials and products made from them according to the design solution scenarios considering their LCA. The model implements the GRA method and environmental impact analysis according to the LCA based on ISO 14040. The model test was carried out for light passenger vehicles of BEV with a lithium-ion battery (LiFePO4) and for ICEV. The results indicated a relatively comparable level of quality, but in the case of the environmental impact throughout the life-cycle, the predominant amount of CO2 emissions in the use phase for combustion vehicles. The originality of the developed model to create scenarios of design solutions is created according to which the optimal direction of their development in terms of quality and environment throughout LCA can be predicted.

Differential temporal release and lipoprotein loading in B. thetaiotaomicron bacterial extracellular vesicles

Bacterial extracellular vesicles (BEVs) contribute to stress responses, quorum sensing, biofilm formation and interspecies and interkingdom communication. However, the factors that regulate their release and heterogeneity are not well understood. We set out to investigate these factors in the common gut commensal Bacteroides thetaiotaomicron by studying BEV release throughout their growth cycle. Utilising a range of methods, we demonstrate that vesicles released at different stages of growth have significantly different composition, with early vesicles enriched in specifically released outer membrane vesicles (OMVs) containing a larger proportion of lipoproteins, while late phase BEVs primarily contain lytic vesicles with enrichment of cytoplasmic proteins. Furthermore, we demonstrate that lipoproteins containing a negatively charged signal peptide are preferentially incorporated in OMVs. We use this observation to predict all Bacteroides thetaiotaomicron OMV enriched lipoproteins and analyse their function. Overall, our findings highlight the need to understand media composition and BEV release dynamics prior to functional characterisation and define the theoretical functional capacity of Bacteroides thetaiotaomicron OMVs.

An extensive review on hybrid electric vehicles powered by fuel cell-enabled hybrid energy storage system

To overcome the air pollution and ill effects of IC engine-based transportation (ICEVs), demand of electric vehicles (EVs) has risen which reduce *gasoline consumption, environment degradation and energy wastage, but barriers-short driving range, higher battery cost and longer charging time-slow down its wide adoptions and commercialization. Although to overcome such issues, EV variants -HEVs and PHEVs-were also brought into the market but not that successful either. The use of ICE in HEVs and PHEVs increases fossil fuel dependency. Thus, the research focus shifted towards fuel cell-powered electric vehicles (FCEVs) which offer negligible emission and higher efficiency than EV variants. Though a moderate research work has been done on FCEVs, still its wide expansion is limited, facing severe challenges commonly related to fuel cost, selection of energy units, power electronic interfacing, component sizing and energy management. This paper presents an extensive exploration on EV variants, their issues, an in-depth comparison of latest topologies for FCEVs and optimum arrangement of HESS, designed by energy unit's integration, i.e. FC, battery and UCs, to encounter the dynamic power demand and develop a performant model for transportation. In last, progress and possible future research areas are discussed. In short, this paper reveals all contemporary information of FCHEV technology to the scientists and scholars who are working in this particular arena.

Self-expanding vs. balloon-expandable transcatheter heart valves in small aortic annuli

Background

Clinical consequences of prosthesis-patient mismatch (PPM) after transcatheter aortic valve replacement (TAVR) is currently in the focus of clinical research. Patients with small aortic annulus are at higher risk to display PPM. Data on incidence and clinical consequences of PPM after TAVR with either balloon-expandable (BEV) or self-expanding (SEV) transcatheter heart valves in small aortic annulus are sparse.

Methods

Patients with small aortic annulus (perimeter < 72 mm or aortic annulus area < 400 mm2) who underwent BEV or SEV with contemporary transcatheter heart valve types were identified from the institutional TAVR database. Propensity score matching was applied for imbalanced baseline characteristics between patients undergoing BEV or SEV. Echocardiography and clinical follow-up beyond 3 years was reported following VARC-3 recommendations. Primary endpoint was the incidence of pre-discharge PPM and its association with 3-year mortality.

Results

From a total of 507 patients with small aortic annulus, 192 matched patient pairs with SEV or BEV were identified. Mean age was 81 ± 7 (SEV) vs. 81 ± 6 (BEV) years (p = 0.5), aortic annulus perimeter was 69 ± 3 vs.69 ± 3 mm, (p = 0.8), annulus area was 357 ± 27 vs.357 ± 27 mm2 (p = 0.8), and EuroScore II was 5.8 ± 6.6 vs.5.7 ± 7.2 (p = 0.9). SEV resulted in less moderate (20% vs. 31%, p < 0.001) and severe pre-discharge PPM (9% vs.18%, p < 0.001) compared to BEV. At discharge (7 ± 4 vs. 12 ± 9 mmHg, p = 0.003) and at 1-year follow-up (7 ± 5 vs.13 ± 3 mmHg, p < 0.001), SEV displayed lower mean gradients compared to BEV. Estimated survival after SEV was 85% (95% confidence interval (CI): 80%-90%) at 1 year, 80% (95% CI: 75%-86%) at 2 years, and 71% (95% CI: 65%-78%) at 3 years; estimated survival after BEV was 87% (95% CI: 82%-92%) at 1 year, 81% (95% CI: 75%-86%) at 2 years, and 72% (95% CI: 66%-79%) at 3 years, with no significant difference among the groups (p = 0.9) Body surface area (OR: 1.35, p < 0.001), implantation of BEV (odds ratio (OR): 3.32, p < 0.001), and the absence of postdilatation (OR: 2.16, p < 0.001) were independent risk factors for any PPM. At 3 years, patients without PPM had a higher 3-year survival compared with patients with ≥moderate PPM (77% vs. 67%, p = 0.03).

Conclusion

BEV implantation in patients with small annulus was associated with a twofold higher incidence of pre-discharge severe PPM compared to SEV implantation. Survival at 3 years after TAVR was similar after BEV and SEV. However, patients with the absence of pre-discharge PPM had a higher 3-year survival compared to patients with ≥moderate PPM.

Technical Note: Combination of multiple EPID imager layers improves image quality and tracking performance of low contrast-to-noise objects

PURPOSE

We hypothesized that combining multiple amorphous silicon flat panel layers increases photon detection efficiency in an electronic portal imaging device (EPID), improving image quality and tracking accuracy of low-contrast targets during radiotherapy.

METHODS

The prototype imager evaluated in this study contained four individually programmable layers each with a copper converter layer, Gd₂ O₂ S scintillator, and active-matrix flat panel imager (AMFPI). The imager was placed on a Varian TrueBeam linac and a Las Vegas phantom programmed with sinusoidal motion (peak-to-peak amplitude = 20 mm, period = 3.5 s) was imaged at a frame rate of 10 Hz with one to four layers activated. Number of visible circles and CNR of least visible circle (depth = 0.5 mm, diameter = 7 mm) was computed to assess the image quality of single and multiple layers. A previously validated tracking algorithm was employed for auto-tracking. Tracking error was defined as the difference between the programmed and tracked positions of the circle. Pearson correlation coefficient (R) of CNR and tracking errors was computed.

RESULTS

Motion-induced blurring significantly reduced circle visibility. During four cycles of phantom motion, the number of visible circles varied from 11-23, 13-24, 15-25, and 16-26 for one-, two-, three-, and four-layer imagers, respectively. Compared with using only a single layer, combining two, three, and four layers increased the median CNR by factors of 1.19, 1.42, and 1.71, respectively and reduced the average tracking error from 3.32 mm to 1.67 mm to 1.47 mm, and 0.74 mm, respectively. Significant correlations (P~10^-9 ) were found between the tracking error and CNR.

CONCLUSION

Combination of four conventional EPID layers significantly improves the EPID image quality and tracking accuracy for a poorly visible object which is moving with a frequency and amplitude similar to respiratory motion.

Life cycle assessment of mobility options using wood based fuels--comparison of selected environmental effects and costs

An environmental assessment and a cost analysis were conducted for mobility options using electricity, hydrogen, ethanol, Fischer-Tropsch diesel and methane derived from wood. Therefore, the overall life cycle with regard to greenhouse gas emissions, acidifying emissions and fossil energy demand as well as costs is analysed. The investigation is carried out for mobility options in 2010 and gives an outlook to the year 2030. Results show that methane utilization in the car is beneficial with regard to environmental impacts (e.g. 58.5 g CO2-eq./km) and costs (23.1 €-ct./km) in 2010, especially in comparison to hydrogen usage (132.4 g CO2-eq./km and 63.9 €-ct./km). The electric vehicle construction has high environmental impacts and costs compared to conventional vehicles today, but with technical improvements and further market penetration, battery electric vehicles can reach the level of concepts with combustion engines in future applications (e.g. cost decrease from 38.7 to 23.4 €-ct./km).