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RESIDENSITY : a carbon analysis of residential typologies
RESIDENSITY: A Carbon Analysis of Residential Typologies' is the culmination of a seven-year study analysing nine building typologies to understand the relationships between building densities and the amount of land and infrastructure required to support them.0The book investigates how much embodied and consumed carbon is used in each typology and how it affects density and open space from the viewpoint of sustainability, carbon emissions, and carbon sequestration. The study determines which building typology is the most sustainable on a comparative basis. Nine prototypical buildings were designed - Megatall, Supertall, High-Rise, Mid-Rise, Low-rise, Courtyard, Three-Flat, Urban Single-Family, and Suburban Single-Family - set within nine prototypical communities. The study designates an archetypal residential community of 2,000 units with an average unit size of 150 sm as a reasonable and representative cross section of different housing typologies.
Book
Investigation on the Linear Energy Storage and Dissipation Laws of Rock Materials Under Uniaxial Compression
To investigate the energy evolution characteristics of rock materials under uniaxial compression, the single-cyclic loading–unloading uniaxial compression tests of four rock materials (Qingshan granite, Yellow sandstone, Longdong limestone and Black sandstone) were conducted under five unloading stress levels. The stress–strain curves and failure characteristics of rock specimens under the single-cyclic loading–unloading uniaxial compression tests basically corresponded with those of under uniaxial compression, which indicates that single-cyclic loading–unloading has minimal effects on the variations in the loading–deformation response of rocks. The input energy density, elastic energy density and dissipated energy density of four rocks under five unloading stress levels were calculated using the graphical integration method, and variation characteristics of those three energy density parameters with different unloading stress levels were explored. The results show that all three energy density parameters above increased nonlinearly with increasing unloading stress level as quadratic polynomial functions. Meanwhile, both the elastic and dissipated energy density increased linearly when the input energy density increased, and the linear energy storage and dissipation laws for rock materials were observed. Furthermore, a linear relationship between the dissipated and elastic energy density was also proposed. Using the linear energy storage or dissipation law, the elastic and dissipated energy density at any stress levels can be calculated, and the internal elastic (or dissipated) energy density at peak compressive strength (the peak elastic and dissipated energy density for short) can be obtained. The ratio of the elastic energy density to dissipated energy density with increasing input energy density was investigated using a new method, and the results show that this ratio tends to be constant at the peak compressive strength of rock specimens.
Journal Article
A study of the characteristics of white noise using the empirical mode decomposition method
Based on numerical experiments on white noise using the empirical mode decomposition (EMD) method, we find empirically that the EMD is effectively a dyadic filter, the intrinsic mode function (IMF) components are all normally distributed, and the Fourier spectra of the IMF components are all identical and cover the same area on a semi-logarithmic period scale. Expanding from these empirical findings, we further deduce that the product of the energy density of IMF and its corresponding averaged period is a constant, and that the energy-density function is chi-squared distributed. Furthermore, we derive the energy-density spread function of the IMF components. Through these results, we establish a method of assigning statistical significance of information content for IMF components from any noisy data. Southern Oscillation Index data are used to illustrate the methodology developed here.
Journal Article
Electron acceleration in laboratory-produced turbulent collisionless shocks
Astrophysical collisionless shocks are among the most powerful particle accelerators in the Universe. Generated by violent interactions of supersonic plasma flows with the interstellar medium, supernova remnant shocks are observed to amplify magnetic fields
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and accelerate electrons and protons to highly relativistic speeds
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–
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. In the well-established model of diffusive shock acceleration
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, relativistic particles are accelerated by repeated shock crossings. However, this requires a separate mechanism that pre-accelerates particles to enable shock crossing. This is known as the ‘injection problem’, which is particularly relevant for electrons, and remains one of the most important puzzles in shock acceleration
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. In most astrophysical shocks, the details of the shock structure cannot be directly resolved, making it challenging to identify the injection mechanism. Here we report results from laser-driven plasma flow experiments, and related simulations, that probe the formation of turbulent collisionless shocks in conditions relevant to young supernova remnants. We show that electrons can be effectively accelerated in a first-order Fermi process by small-scale turbulence produced within the shock transition to relativistic non-thermal energies, helping overcome the injection problem. Our observations provide new insight into electron injection at shocks and open the way for controlled laboratory studies of the physics underlying cosmic accelerators.
In laser–plasma experiments complemented by simulations, electron acceleration is observed in turbulent collisionless shocks. This work clarifies the pre-acceleration to relativistic energies required for the onset of diffusive shock acceleration.
Journal Article
Practical evaluation of prelithiation strategies for next‐generation lithium‐ion batteries
With the increasing market demand for high‐performance lithium‐ion batteries with high‐capacity electrode materials, reducing the irreversible capacity loss in the initial cycle and compensating for the active lithium loss during the cycling process are critical challenges. In recent years, various prelithiation strategies have been developed to overcome these issues. Since these approaches are carried out under a wide range of conditions, it is essential to evaluate their suitability for large‐scale commercial applications. In this review, these strategies are categorized based on different battery assembling stages that they are implemented in, including active material synthesis, the slurry mixing process, electrode pretreatment, and battery fabrication. Furthermore, their advantages and disadvantages in commercial production are discussed from the perspective of thermodynamics and kinetics. This review aims to provide guidance for the future development of prelithiation strategies toward commercialization, which will potentially promote the practical application of next‐generation high‐energy‐density lithium‐ion batteries. Considering the pressing need for standard prelithiation techniques for large‐scale production, herein, together with experts from the industry, we summarize the advantages and challenges of each prelithiation strategy from material synthesis to battery fabrication, and elaborate the scientific principles for lithiation. By evaluating the practicality of various prelithiation approaches, we seek to bridge the gap between academia and industry.
Journal Article
Insights into layered–tunnel dynamic structural evolution based on local coordination chemistry regulation for high‐energy‐density and long‐cycle‐life sodium‐ion oxide cathodes
The pursuit of high energy density while achieving long cycle life remains a challenge in developing transition metal (TM) oxide cathode materials for sodium‐ion batteries (SIBs). Here, we present a concept of precisely manipulating structural evolution via local coordination chemistry regulation to design high‐performance composite cathode materials. The controllable structural evolution process is realized by tuning magnesium content in Na 0.6 Mn 1− x Mg x O 2 , which is elucidated by a combination of experimental analysis and theoretical calculations. The substitution of Mg into Mn sites not only induces a unique structural evolution from layered–tunnel structure to layered structure but also mitigates the Jahn–Teller distortion of Mn 3+ . Meanwhile, benefiting from the strong ionic interaction between Mg 2+ and O 2− , local environments around O 2− coordinated with electrochemically inactive Mg 2+ are anchored in the TM layer, providing a pinning effect to stabilize crystal structure and smooth electrochemical profile. The layered–tunnel Na 0.6 Mn 0.95 Mg 0.05 O 2 cathode material delivers 188.9 mAh g −1 of specific capacity, equivalent to 508.0 Wh kg −1 of energy density at 0.5C, and exhibits 71.3% of capacity retention after 1000 cycles at 5C as well as excellent compatibility with hard carbon anode. This work may provide new insights of manipulating structural evolution in composite cathode materials via local coordination chemistry regulation and inspire more novel design of high‐performance SIB cathode materials. image
Journal Article
Calculation of Strain Energy Density Function Using Ogden Model and Mooney–Rivlin Model Based on Biaxial Elongation Experiments of Silicone Rubber
Strain energy density functions are used in CAE analysis of hyperelastic materials such as rubber and elastomers. This function can originally be obtained only by experiments using biaxial deformation, but the difficulty of such experiments has made it almost impossible to put the function to practical use. Furthermore, it has been unclear how to introduce the strain energy density function necessary for CAE analysis from the results of biaxial deformation experiments on rubber. In this study, parameters of the Ogden and Mooney–Rivlin approximations of the strain energy density function were derived from the results of biaxial deformation experiments on silicone rubber, and their validity was verified. These results showed that it is best to determine the coefficients of the approximate equations for the strain energy density function after 10 cycles of repeated elongation of rubber in an equal biaxial deformation state, followed by equal biaxial elongation, uniaxial constrained biaxial elongation, and uniaxial elongation to obtain these three stress–strain curves.
Journal Article
A review of solid electrolytes for safe lithium-sulfur batteries
Due to the high specific capacity, low cost, and environmental friendliness, lithium-sulfur batteries hold great potential to become the mainsiay of next-generation energy storage system. Regarding the composition of sulfur/carbon in cathode, flammable organic liquid electrolyte, and lithium metal anode, great concerns about the safety have been raised. Hence solid-electrolyte-based lithium-sulfur batteries, as one alternative route for safe batteries, are highly interested. This review highlights the recent research progress of lithium-sulfur batteries with solid electrolytes. Both sulfide solid electrolytes and oxide solid electrolytes are included. The sulfide solid electrolytes are mainly employed in all-solid-state lithium-sulfur batteries, while the oxide solid electrolytes are applied in hybrid electrolyte for lithium-sulfur batteries. The challenges and perspectives in this field are also featured on the basis of its current progress.
Journal Article
A New In Situ Prepared MOF‐Natural Polymer Composite Electrolyte for Solid Lithium Metal Batteries with Superior High‐ Rate Capability and Long‐Term Cycling Stability at Ultrahigh Current Density
Lithium metal batteries hold promise for energy storage applications but suffer from uncontrolled lithium dendrites. In this study, a new composite membrane based on modified natural polymer and ZIF‐67 is designed and prepared by the in situ composite method for the first time. Among them, a modified natural polymer composed of lithium alginate (LA) and polyacrylamide (PAM) can be obtained by electrospinning. Importantly, the polar functional groups of natural polymers can interact by hydrogen bonding and MOFs can construct lithium‐ion transport channels. Consequently, compared with LA‐PAM electrolyte without MOF, the electrochemical stability window of ZIF‐67‐LA‐PAM electrolyte becomes wider from 4.5 to 5.2 V, and the lithium‐ion transference number (tLi+) enhances from 0.326 to 0.627 at 30°C. It is worth noting that the symmetric cells with ZIF‐67‐LA‐PAM have superior stable cycling performance at 40 and 100 mA cm−2, and a high rate at 10C and 20C for LFP cells. Besides, the cell with NCM811 high‐voltage cathode can run stably for 400 cycles with an initial discharge capacity of 136.1 mAh g−1 at 0.5C. This work provides an effective method for designing and preparing MOF‐natural polymer composite electrolytes and exhibits an excellent application prospect in high‐energy‐density lithium metal batteries. A natural polymer composite electrolyte is prepared by in situ synthesis of ZIF‐67 on a modified lithium alginate electrospinning membrane. The assembled cells can run stably for 1300 h at 100 mA cm−2 for symmetric cells, 1600 cycles at 20C for LFP cells, and even 400 cycles at 2C for pouch cells. The obtained electrolyte can also well adapt to the NCM811 electrode.
Journal Article
Recent advances and challenges in the design of Li–air batteries oriented solid‐state electrolytes
Solid‐state Li–air batteries with ultrahigh energy density and safety are promising for long‐range electric vehicles and special electronics. However, the challenging issues of developing Li–air battery‐oriented solid‐state electrolytes (SSEs) with high ionic conductivity, interfacial compatibility, and stability to boost reversibility, increase stable triple‐phase boundaries, and protect the Li anode in an open system substantially impede their applications. Herein, we systematically summarize the recent progress achieved in terms of SSEs for Li–air batteries, and describe in detail the basic characteristics of SSE|air cathode interfaces and SSE|Li anode interfaces. First, the major characteristics of SSEs in Li–air batteries in terms of ionic/electronic conductivity, chemical/electrochemical/thermal stability, mechanical strength, and interfacial compatibility are briefly introduced according to three types of SSEs: inorganic, organic, and hybrid SSEs. Second, key strategies of integrating catalytic sites, porous structures, and electronic conductors with SSEs to enhance triple‐phase boundaries at the SSE|air cathode for improving Coulombic efficiency are described in detail. Moreover, the protection of Li metal from H2O, CO2, O2, and redox mediators at the SSE|Li anode to ensure safety is elaborately overviewed. Finally, future opportunities and perspectives on three important topics of three‐dimensional structural integration, external field assistance, and operando characterizations are proposed for advanced solid‐state Li–air batteries. The recent progress achieved in terms of SSEs for Li–air batteries is systematically summarized. First, the major characteristics of SSEs in Li–air batteries in terms of ionic/electronic conductivity, chemical/electrochemical/thermal stability, mechanical strength, and interfacial compatibility are briefly introduced. Second, key strategies of integrating catalytic sites, porous structures, and electronic conductors with SSEs to enhance triple‐phase boundaries at the SSE|air cathode are described in detail. Finally, protection of Li metal from H2O, CO2, O2, and redox mediators at the SSE|Li anode to ensure safety is elaborately overviewed.
Journal Article