Urban street canyons formed by high-rise buildings restrict the dispersion of vehicle emissions, which pose severe health risks to the public by aggravating roadside air quality. However, this issue ...is often overlooked in city planning. This paper reviews the mechanisms controlling vehicle emission dispersion in urban street canyons and the strategies for managing roadside air pollution. Studies have shown that air pollution hotspots are not all attributed to heavy traffic and proper urban design can mitigate air pollution. The key factors include traffic conditions, canyon geometry, weather conditions and chemical reactions. Two categories of mitigation strategies are identified, namely traffic interventions and city planning. Popular traffic interventions for street canyons include low emission zones and congestion charges which can moderately improve roadside air quality. In comparison, city planning in terms of building geometry can significantly promote pollutant dispersion in street canyons. General design guidelines, such as lower canyon aspect ratio, alignment between streets and prevailing winds, non-uniform building heights and ground-level building porosity, may be encompassed in new development. Concurrently, in-street barriers are widely applicable to rectify the poor roadside air quality in existing street canyons. They are broadly classified into porous (e.g. trees and hedges) and solid (e.g. kerbside parked cars, noise fences and viaducts) barriers that utilize their aerodynamic advantages to ease roadside air pollution. Post-evaluations are needed to review these strategies by real-world field experiments and more detailed modelling in the practical perspective.
Display omitted
•Key influences are canyon geometry, traffic and weather conditions, and chemical reactions.•Traffic interventions in street canyons lead to moderate improvement of roadside air quality.•Well-designed canyon geometry significantly enhances dispersion of emissions.•Combining solid and porous in-street barriers is more effective than individual use.•Traffic control and in-street barriers are more implementable than canyon geometry design.
A direct regeneration of cathode materials from spent LiFePO
4
batteries using a solid phase sintering method has been proposed in this article. The spent battery is firstly dismantled to separate ...the cathode and anode plate, and then the cathode plate is soaked in DMAC organic solvent to separate the cathode materials and Al foil at optimal conditions of 30 min at 30 °C and solid liquid ratio of 1 : 20 g ml
−1
. XRD and SEM results of the spent LiFePO
4
after separation show that there are some impurity phase components and irregular morphologies with many agglomerations. The spent materials are regenerated at appropriate temperatures with doping of new LiFePO
4
at different ratios. Battery capacities from regenerated LiFePO
4
can reach over 120 mA h g
−1
at 0.1C discharge conditions, especially with the highest value of 144 mA h g
−1
with a doping ratio of 3 : 7 at 700 °C. The rate capabilities and cycling performance of batteries made from regenerated LiFePO
4
with doping at 600 °C and 700 °C are generally better than those at 800 °C. All the performances of batteries made from regenerated LiFePO
4
with pure phase and uniform morphology can meet the basic requirements for reuse.
A direct regeneration of cathode materials from spent LiFePO
4
batteries using a solid phase sintering method has been proposed in this article.
Realizing quantum speedup for practically relevant, computationally hard problems is a central challenge in quantum information science. Using Rydberg atom arrays with up to 289 qubits in two spatial ...dimensions, we experimentally investigate quantum algorithms for solving the Maximum Independent Set problem. We use a hardware-efficient encoding associated with Rydberg blockade, realize closed-loop optimization to test several variational algorithms, and subsequently apply them to systematically explore a class of graphs with programmable connectivity. We find the problem hardness is controlled by the solution degeneracy and number of local minima, and experimentally benchmark the quantum algorithm's performance against classical simulated annealing. On the hardest graphs, we observe a superlinear quantum speedup in finding exact solutions in the deep circuit regime and analyze its origins.
Arterial hemodynamic shear stress and blood vessel stiffening both significantly influence the arterial endothelial cell (EC) phenotype and atherosclerosis progression, and both have been shown to ...signal through cell-matrix adhesions. However, the cooperative effects of fluid shear stress and matrix stiffness on ECs remain unknown. To investigate these cooperative effects, we cultured bovine aortic ECs on hydrogels matching the elasticity of the intima of compliant, young, or stiff, aging arteries. The cells were then exposed to laminar fluid shear stress of 12 dyn/cm2. Cells grown on more compliant matrices displayed increased elongation and tighter EC-cell junctions. Notably, cells cultured on more compliant substrates also showed decreased RhoA activation under laminar shear stress. Additionally, endothelial nitric oxide synthase and extracellular signal-regulated kinase phosphorylation in response to fluid shear stress occurred more rapidly in ECs cultured on more compliant substrates, and nitric oxide production was enhanced. Together, our results demonstrate that a signaling cross talk between stiffness and fluid shear stress exists within the vascular microenvironment, and, importantly, matrices mimicking young and healthy blood vessels can promote and augment the atheroprotective signals induced by fluid shear stress. These data suggest that targeting intimal stiffening and/or the EC response to intima stiffening clinically may improve vascular health.
ABSTRACT
The presented work investigates the possible formation of terrestrial planets in the habitable zone (HZ) of the exoplanetary system HD 141399. In this system, the HZ is located approximately ...between the planets c (a = 0.7 au) and d (a = 2.1 au). Extensive numerical integrations of the equations of motion in the pure Newtonian framework of small bodies with different initial conditions in the HZ are performed. Our investigations included several steps starting with 500 massless bodies distributed between planets c and d in order to model the development of the disc of small bodies. It turns out that after some 106 yr, a belt-like structure analogue to the main belt inside Jupiter in our Solar system appears. We then proceed with giving the small bodies masses (∼ Moon mass) and take into account the gravitational interaction between these planetesimal-like objects. The growing of the objects – with certain percentage of water – due to collisions is computed in order to look for the formation of terrestrial planets. We observe that planets form in regions connected to mean motion resonances (MMR). So far there is no observational evidence of terrestrial planets in the system of HD 141399 but from our results we can conclude that the formation of terrestrial planets – even with an appropriate amount of water necessary for being habitable – in the HZ would have been possible.
As a core component of AC drive electric locomotive, performance of inverter-fed motor directly influences the stability and reliability of locomotive running. However, insulation early failures ...occur frequently. Presently, polyimide film, as a special type of engineering plastic film, widely applied in turn to turn insulation and turn to ground insulation of inverter-fed motors is a kind of basic insulating material. This paper investigates charge transport mechanism and space charge characteristics of polyimide films based on measuring and comparing space charge accumulation threshold field between corona-resistant and common polyimide films and analyzing the effect of temperature on space charge distribution. The results reveal that space charge accumulation threshold field of corona-resistant polyimide film is higher than that of common polyimide film; the adding of nano-particles effectively increases dielectric properties of corona-resistant film. Additionally, raising temperature promotes the electrode injecting charge and increases the charge energy and conductivity which gradually enhances space charge number and extends trapping position into the bulk, closely related to polyimide film insulation aging and breakdown which is an important characteristic.
The bullwhip effect, also known as demand information amplification, is one of the principal obstacles in supply chains. In recent decades, extensive studies have explored its operational causes and ...have proposed corresponding solutions in the context of production inventory and supply chain systems. However, the underlying assumption of these studies is that human decision-making is always rational. Yet, this is not always the case, and an increasing number of recent studies have argued that behavioural and psychological factors play a key role in generating the bullwhip effect in real-world supply chains. Given the prevalence of such research, the main objective of this study is to provide a systematic literature review on the bullwhip effect from the behavioural operations perspective. Using databases, including Scopus, Wiley Online Library, Google Scholar and Science Direct, we selected, summarised and analysed 53 academic studies. We find that most studies build their models and simulations based on the ‘beer distribution game’ and analyse the results at the individual level. We also demonstrate the importance of studying human factors in the bullwhip effect through adapting Sterman's double-loop learning model. Based on this model, we categorise and analyse the behavioural factors that have been studied and identify the explored behavioural factors for future research. Based on our findings, we suggest that future studies could consider social and cultural influences on decision-making in studying the bullwhip effect. In addition, further aspects of human mental models that cause this effect can be explored.
In simulating two-phase combustion, most Reynolds-averaged Navier–Stokes (RANS) simulation and large-eddy simulation (LES) used Eulerian–Lagrangian (E–L) modeling (Eulerian treatment of gas phase and ...Lagrangian treatment of particles/droplets) which needs much more computational time than the Eulerian–Eulerian (E–E) or two-fluid modeling. However, in the E–E modeling, the problem of how to reduce the computation time for poly-dispersed particles is encountered . To solve this problem, the present author proposed an Eulerian–Eulerian–Lagrangian (E–E–L) modeling of two-phase combustion for both RANS modeling and LES. The E–E–L modeling is an Eulerian treatment of gas phase and a combined Eulerian–Lagrangian treatment of particles/droplets, in which the particle velocity and concentration are solved by Eulerian modeling, and particle temperature and mass change due to reaction are solved by Lagrangian modeling. In this paper, a review is given for an E–E–L modeling of coal combustion, its application in RANS simulation and its possible application in LES. For E–E–L LES, an energy equation model of two-phase sub-grid scale (SGS) stresses accounting for the interaction between two-phase SGS stresses is suggested, and a second-order moment SGS (SOM-SGS) turbulence-chemistry model is adopted to simulate gas-phase reaction in two-phase combustion. These SGS models were separately assessed by comparison with experiments.
Graphic abstract
Effect of solutes on grain refinement Fan, Z.; Gao, F.; Wang, Y. ...
Progress in materials science,
January 2022, 2022-01-00, 20220101, Letnik:
123
Journal Article
Recenzirano
Odprti dostop
Grain refinement not only enhances the mechanical performance of as-cast metallic materials but also provides an effective mechanism for controlling cast defects, such as macro-segregation, porosity ...and coarse second phase particles. Therefore, understanding grain refinement of alloys with different solute additions is of both theoretical and practical importance. Although extensive research has been carried out over many decades and significant progress has been made on the subject, such historical research has not delivered the desirable scientific understanding, and many critical questions remain open. Adopting a hybrid approach between review and overview, in this paper, we firstly provide a brief review on the historical research on the solute effect on grain refinement in the literature, then present the recent advances in the understanding of the subject in a holistic manner, and finally offer a summary of the factors that hindered progress in the past, key advances made in recent years and some suggestions for future research directions.
Characterization of porous media is essential in a wide range of biomedical and industrial applications. Microstructural features can be probed non-invasively by diffusion magnetic resonance imaging ...(dMRI). However, diffusion encoding in conventional dMRI may yield similar signatures for very different microstructures, which represents a significant limitation for disentangling individual microstructural features in heterogeneous materials. To solve this problem, we propose an augmented multidimensional diffusion encoding (MDE) framework, which unlocks a novel encoding dimension to assess time-dependent diffusion specific to structures with different microscopic anisotropies. Our approach relies on spectral analysis of complex but experimentally efficient MDE waveforms. Two independent contrasts to differentiate features such as cell shape and size can be generated directly by signal subtraction from only three types of measurements. Analytical calculations and simulations support our experimental observations. Proof-of-concept experiments were applied on samples with known and distinctly different microstructures. We further demonstrate substantially different contrasts in different tissue types of a post mortem brain. Our simultaneous assessment of restriction size and shape may be instrumental in studies of a wide range of porous materials, enable new insights into the microstructure of biological tissues or be of great value in diagnostics.
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