The wave-induced fluid flow(WIFF) occurring in the ubiquitous layered porous media(e.g.,shales)usually causes the appreciable seismic energy dissipation,which further leads to the frequency dependence of wave velocity...The wave-induced fluid flow(WIFF) occurring in the ubiquitous layered porous media(e.g.,shales)usually causes the appreciable seismic energy dissipation,which further leads to the frequency dependence of wave velocity(i.e.,dispersion) and elastic anisotropy parameters.The relevant knowledge is of great importance for geofluid discrimination and hydrocarbon exploration in the porous shale reservoirs.We derive the wave equations for a periodic layered transversely isotropy medium with a vertical axis of symmetry(VTI) concurrently with the annular cracks(PLPC medium) based on the periodic-layered model and anisotropic Biot's theory,which simultaneously incorporate the effects of microscopic squirt fluid flow,mesoscopic interlayer fluid flow and macroscopic global fluid flow.Notably,the microscopic squirt shorten fluid flow emerges between the annular-shaped cracks and stiff pores,which generates one attenuation peak.Specifically,we first establish the stress-strain relationship and pore fluid pressure in a PLPC medium,and then use them to derive the wave equations by means of the Newton's second law.The plane analysis is implemented on the wave equations to yield the analytic solutions for phase velocities and attenuation factors of four waves,namely,fast P-wave,slow P-wave,SV-wave and SH-wave,and the anisotropy parameters can be therefore computed.Simulation results show that P-wave velocity have three attenuation peaks throughout the full frequency band,which respectively correspond to the influences of interlayer flow,the squirt flow and the Biot flow.Through the results of seismic velocity dispersion and attenuation at different incident angles,we find that the WIFF mechanism also has a significant impact on the dispersion characteristics of elastic anisotropy parameters within the low-mid frequency band.Moreover,it is shown that several poroelastic parameters,such as layer thickness ratio,crack aspect ratio and crack density have notable influence on seismic dispersion and attenuation.We compare the proposed modeled velocities with that given by the existing theory to confirm its validity.Our formulas and result can provide a better understanding of wave propagation in PLPC medium by considering the unified impacts of micro-,meso-and macro-scale WIFF mechanisms,which potentially lays a theoretical basis of rock physics for seismic interpretation.展开更多
Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure throug...Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure through self-priming. However, their pressure frequency and cavitation characteristics remain unclear, resulting in an inability to fully utilize resonance and cavitation erosion to break coal and rock. In this study, high-frequency pressure testing, high-speed photography, and large eddy simulation(LES) are used to investigate the distribution of the pressure frequency band, evolution law of the cavitation cloud, and its regulation mechanism of a continuous waterjet, SOPW, and AFESOPW. The results indicated that the excitation of the plunger pump, shearing layer vortex, and bubble collapse corresponded to the three high-amplitude frequency bands of the waterjet pressure. AFESOPWs have an additional self-priming frequency that can produce a larger amplitude under a synergistic effect with the second high-amplitude frequency band. A better cavitation effect was produced after self-priming the annulus fluid, and the shedding frequency of the cavitation clouds of the three types of waterjets was linearly related to the cavitation number. The peak pressure of the waterjet and cavitation erosion effect can be improved by modulating the waterjet pressure oscillation frequency and cavitation shedding frequency.展开更多
The successful application of perimeter control of urban traffic system strongly depends on the macroscopic fundamental diagram of the targeted region.Despite intensive studies on the partitioning of urban road networ...The successful application of perimeter control of urban traffic system strongly depends on the macroscopic fundamental diagram of the targeted region.Despite intensive studies on the partitioning of urban road networks,the dynamic partitioning of urban regions reflecting the propagation of congestion remains an open question.This paper proposes to partition the network into homogeneous sub-regions based on random walk algorithm.Starting from selected random walkers,the road network is partitioned from the early morning when congestion emerges.A modified Akaike information criterion is defined to find the optimal number of partitions.Region boundary adjustment algorithms are adopted to optimize the partitioning results to further ensure the correlation of partitions.The traffic data of Melbourne city are used to verify the effectiveness of the proposed partitioning method.展开更多
Microbial fuel cells(MFCs)are promising for realizing wastewater remediation and electricity co-generation,which may significantly promote the formation of an environmentally friendly,clean energy society.Unfortunatel...Microbial fuel cells(MFCs)are promising for realizing wastewater remediation and electricity co-generation,which may significantly promote the formation of an environmentally friendly,clean energy society.Unfortunately,most of the available MFCs show relatively low electricity generation.Anodes,the major component of MFCs,play the most critical role in electron transfer and organic decomposition,which directly determine the performance of MFCs.In the past decades,various carbonaceous materials and carbon-supported conductive composites have been extensively exploited to optimize the electron transfer on the anode due to their versatile properties,such as large surface area and excellent electrical conductivity.The development of anode materials with a particular structure and performance to satisfy field-scale long-term operation of MFCs remains a huge research challenge,which attracts great attention and urgently needs in-depth exploration of the material engineering of anodes for MFCs.In this review,recent advances in the development and optimization of anodes for MFCs are summarized,and applications of MFCs with advanced anodes in the remediation of different types of wastewater are discussed.Advances of anodes for promoting electron transfer,microbial attachment and organic decomposition are the main focuses.The superiorities of MFCs on different aspects of wastewater remediation are elucidated,along with perspectives on future research of MFCs,aiming to provide useful guidance in related fields.展开更多
Background:While muscle contractility increases with muscle temperature,there is no consensus on the best warm-up protocol to use before resistance training or sports exercise due to the range of possible warm-up and ...Background:While muscle contractility increases with muscle temperature,there is no consensus on the best warm-up protocol to use before resistance training or sports exercise due to the range of possible warm-up and testing combinations available.Therefore,the objective of the current study was to determine the effects of different warm-up types(active,exercise-based vs.passive)on muscle function tested using different activation methods(voluntary vs.evoked)and performance test criteria(maximum force vs.rate-dependent contractile properties),with consideration of warm-up task specificity(specific vs.non-specific),temperature measurement method(muscle vs.skin),baseline temperatures,and subject-specific variables(training status and sex).Methods:A systematic search was conducted in PubMed/MEDLINE,Scopus,Web of Science,Cochrane,Embase,and ProQuest.Random-effects meta-analyses and meta-regressions were used to compute the effect sizes(ES)and 95%confidence intervals(95%CIs)to examine the effects of warm-up type,activation method,performance criterion,subject characteristics,and study design on temperature-related performance enhancement.Results:The search yielded 1272 articles,of which 33 met the inclusion criteria(n=921).Increasing temperature positively affected both voluntary(3.7%/℃±1.8%/℃(mean±SD),ES=0.28(95%CI:0.14 to 0.41))and evoked(3.2%/℃±1.5%/℃(mean±SD),ES=0.65(95%CI:0.29 to 1.00))rate-dependent contractile properties(dynamic,fast-velocity force production,and rate of force development(RFD))but not maximum force production(voluntary:-0.2%/℃±0.9%/℃(mean±SD),ES=0.08(95%CI:-0.05 to 0.22);evoked:-0.1%/℃±0.8%/℃(mean±SD),ES=-0.20(95%CI:-0.50 to 0.10)).Active warm-up did not induce greater enhancements in rate-dependent contractile properties(p=0.284),maximum force production(p=0.723),or overall function(pooled,p=0.093)than passive warm-up.Meta-regressions did not reveal a significant effect of study design,temperature measurement method,warm-up task specificity,training status,or sex on the effect of increasing temperature(p>0.05).Conclusion:Increasing muscle temperature significantly enhances rate-dependent contractile function(RFD and muscle power)but not maximum force in both evoked and voluntary contractions.In contrast to expectation,no effects of warm-up modality(active vs.passive)or temperature measurement method(muscle vs.skin)were detected,although insufficient data prevented robust sub-group analyses.展开更多
Older adults are at an increased risk of developing knee osteoarthritis.High internal knee abduction moment during daily activities may elevate the risk of knee osteoarthritis.Incline walking exercise has been found t...Older adults are at an increased risk of developing knee osteoarthritis.High internal knee abduction moment during daily activities may elevate the risk of knee osteoarthritis.Incline walking exercise has been found to decrease knee abduction moment in healthy young adults.However,it is unknown if this occurs in healthy older adults.The purpose of this study was to quantify the internal knee abduction moment at different treadmill grades to determine if incline walking could reduce the knee abduction moment in healthy older adults.Twelve healthy older adult males walked on a treadmill at five incline grades(0%,5%,10%,15%,and 20%)at 1.34 m·s^(-1).The primary outcome variable was the internal knee abduction moment.A one-way repeated measures multivariate analysis of variance was performed to determine differences in the dependent variables among incline gradients.Peak knee abduction moment significantly decreased from level walking at all gradients in 10% increments(0%-10%,p<0.001;5%-15%,p<0.002;and 10%-20%,p=0.04).A reduction in knee abduction moment during incline walking could result in decreased knee joint loading on the medial knee compartment.For older adults,who are looking to exercise to improve their health,incline walking may be beneficial to promote lower body strength and cardiovascular ability without inflicting further harm to the aging knee joints.However,because the frontal plane knee joint was of primary interest in this study,further research is needed to determine the effects of incline walking on other joints and in other planes of motion.展开更多
Coal is an essential component of global energy;however,the processes of coal mining and utilization produce significant amounts of coal mine goafs,accompanied by coal-based solid wastes and emitted CO_(2),resulting i...Coal is an essential component of global energy;however,the processes of coal mining and utilization produce significant amounts of coal mine goafs,accompanied by coal-based solid wastes and emitted CO_(2),resulting in severe ecological and environmental challenges.In response to this issue,this study pro-poses a novel approach for filling coal mine goafs using cementitious materials prepared by coal-based solid wastes mineralized with CO_(2)(15%in concentration).The CO_(2) sequestration capacities of individual solid wastes are ranked as follows:carbide slag(CS)>red mud(RM)>fly ash(FA).The performance of filling material prepared from composite solid waste(FA-CS-RM)mineralized with CO_(2) meets the filling requirements of goaf.The filling material(F60C20R20)obtained by CO_(2) mineralization was 14.9 MPa in maximum compressive strength,increasing by 32.2%compared to the non-mineralized material.The prepared filling material exhibits excellent CO_(2) sequestration capacity(i.e.,14.4 kg·t^(−1) in maximum amount of CO_(2) sequestration).According to the analysis of carbon sequestration potential,in China,the annual production of FA,CS,and RM is approximately 899,30,and 107 Mt,respectively in the year of 2023.The utilization of FA,CS,and RM individually can achieve carbon emission reductions of 3.42,10.78,and 0.61 Mt,respectively.The composite solid waste(FA-CS-RM)mineralized with CO_(2) can achieve 1.23 Mt in carbon emissions reduction.Additionally,taking Yellow River Basin of China as a case study,the total volume of underground space in coal mine goafs from 2016 to 2030 is estimated at 8.16 Gm3,indicating that this technology can sequester 0.18 Gt of CO_(2).This approach offers a promising solution for large-scale flue gas CO_(2) sequestration,recycling coal-based solid wastes,and remediating coal mine goafs,contributing to green utilization of coal and the emission reduction of carbon.展开更多
Future 6G communications will open up opportunities for innovative applications,including Cyber-Physical Systems,edge computing,supporting Industry 5.0,and digital agriculture.While automation is creating efficiencies...Future 6G communications will open up opportunities for innovative applications,including Cyber-Physical Systems,edge computing,supporting Industry 5.0,and digital agriculture.While automation is creating efficiencies,it can also create new cyber threats,such as vulnerabilities in trust and malicious node injection.Denialof-Service(DoS)attacks can stop many forms of operations by overwhelming networks and systems with data noise.Current anomaly detection methods require extensive software changes and only detect static threats.Data collection is important for being accurate,but it is often a slow,tedious,and sometimes inefficient process.This paper proposes a new wavelet transformassisted Bayesian deep learning based probabilistic(WT-BDLP)approach tomitigate malicious data injection attacks in 6G edge networks.The proposed approach combines outlier detection based on a Bayesian learning conditional variational autoencoder(Bay-LCVariAE)and traffic pattern analysis based on continuous wavelet transform(CWT).The Bay-LCVariAE framework allows for probabilistic modelling of generative features to facilitate capturing how features of interest change over time,spatially,and for recognition of anomalies.Similarly,CWT allows emphasizing the multi-resolution spectral analysis and permits temporally relevant frequency pattern recognition.Experimental testing showed that the flexibility of the Bayesian probabilistic framework offers a vast improvement in anomaly detection accuracy over existing methods,with a maximum accuracy of 98.21%recognizing anomalies.展开更多
Safe waste disposal is necessary to limit the impact of waste on human health and the environment. This paper evaluates the status of solid waste (SW) disposal in the Wa Municipality, Ghana. The study adopted a descri...Safe waste disposal is necessary to limit the impact of waste on human health and the environment. This paper evaluates the status of solid waste (SW) disposal in the Wa Municipality, Ghana. The study adopted a descriptive research design and applied quantitative and qualitative research methods. 200 questionnaires were administered to two residential areas, each representing high-income, middle-income, and low-income residential dwellings. The study revealed that the majority of the respondents (33.5%) disposed of their SW in open spaces because any collection service did not cover them and those respondents who were covered by a collection service were not satisfied with the collection service due to irregular collection and inconvenient locations of communal collection containers. In addition, all collected SW in the Wa Municipality are openly dumped in illegal dumping sites across the municipality without any form of processing and treatment. The adoption of an integrated solid waste management system could improve SW disposal in the municipality.展开更多
Accurate early classification of elephant flows(elephants)is important for network management and resource optimization.Elephant models,mainly based on the byte count of flows,can always achieve high accuracy,but not ...Accurate early classification of elephant flows(elephants)is important for network management and resource optimization.Elephant models,mainly based on the byte count of flows,can always achieve high accuracy,but not in a time-efficient manner.The time efficiency becomes even worse when the flows to be classified are sampled by flow entry timeout over Software-Defined Networks(SDNs)to achieve a better resource efficiency.This paper addresses this situation by combining co-training and Reinforcement Learning(RL)to enable a closed-loop classification approach that divides the entire classification process into episodes,each involving two elephant models.One predicts elephants and is retrained by a selection of flows automatically labeled online by the other.RL is used to formulate a reward function that estimates the values of the possible actions based on the current states of both models and further adjusts the ratio of flows to be labeled in each phase.Extensive evaluation based on real traffic traces shows that the proposed approach can stably predict elephants using the packets received in the first 10% of their lifetime with an accuracy of over 80%,and using only about 10% more control channel bandwidth than the baseline over the evolved SDNs.展开更多
In many areas around the world, wake surfing has been cited as one of the major causes of lakeshore erosion and turbidity. This paper quantifies the impact related to turbidity and erosion with the use of computationa...In many areas around the world, wake surfing has been cited as one of the major causes of lakeshore erosion and turbidity. This paper quantifies the impact related to turbidity and erosion with the use of computational fluid dynamics (CFD) of boat wakes in shallow water and the build-up of wind driven waves. The energy, type and direction of the boat’s wake are described quantitatively and a table for predicting wind driven waves over varying fetches, depth and wind speeds is provided. The CFD simulation shows that if a wake surf boat is operated 200 ft from shore and in at least 10 ft of water, the environmental impact is minimal.展开更多
In the global south wide range of studies highlight the limitations of the single-modelled public urban water system to meeting the endogenous water preferences of the urban population. Studies also touched on the com...In the global south wide range of studies highlight the limitations of the single-modelled public urban water system to meeting the endogenous water preferences of the urban population. Studies also touched on the complementary roles of private water actors to the single-modelled public water supply system in the urban water supply network. Multiple of urban water supply systems （multi-model） co-exist in the urban landscape of global south. However, it is unclear and largely inconclusive on the suitable and satisfactory urban water supply model that meets the water consumption needs of informal settlement dwellers in the global south. This study draws the experiences of households in the informal settlements using a case-study with cross-sectional survey strategy to assess the suitability of the multi-model urban water supply system for sustainable urban water supply in the informal settlements. A total of 292 households were randomly sampled alongside 35 purposively sampled private water actors and public water departments. The data were collected through face to face interviews. Findings show that water supply services of the multi-model water supply system are inevitably suitable for the water consumption needs of informal settlements’s dwellers. The operation of the multi-model water supply system is flexible and able to accommodate the diverse water consumption preferences and choices of the different socio-economic groups in the informal settlements. We observed that multiplicity of urban water supply system increases households’ access to water but does not necessarily improve the quality of water serve in the informal settlements. The paper recommended for the formalisation and adoption of the multi-model urban water supply system to meet the growing demand for improved water supply and services in the informal settlements.展开更多
Ni-rich LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NCM)cathodes in layered oxide cathodes are attractive for high-energy lithium-ion batteries but suffer from rapid capacity fade and thermal instability at high charge voltages.I...Ni-rich LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NCM)cathodes in layered oxide cathodes are attractive for high-energy lithium-ion batteries but suffer from rapid capacity fade and thermal instability at high charge voltages.In this study,we propose an entropy-assisted multi-element doping strategy to mitigate these issues.Specifically,two routes are designed and compared:bulk-like localized high-entropy doping(BHE-NCM)and surface-distributed high-entropy-zone doping(SHE-NCM).The surface entropy-doped NCM cathode delivers enhanced electrochemical performance,including higher capacity retention under 4.5 V cycling and superior rate capability,compared to both bulk-like and pristine counterparts.Comprehensive material characterization reveals that surface-localized doping stabilizes the layered structure with reduced microcrack formation and creates a uniform dopant-rich surface region with improved thermal and electrochemical stability.Overall,entropy-assisted doping at the near surface zone effectively alleviates structural degradation and interface reactions in Ni-rich NCM,enabling improved cycling performance at high voltage.This work highlights the significance of surface entropy engineering as a promising strategy for designing high-voltage cathodes with improved safety and longevity.展开更多
Slender RC walls are used commonly in mid-and high-rise buildings to resist lateral loads arising from earthquakes and wind forces.To accommodate architectural constraints,facilitate construction,and maximize structur...Slender RC walls are used commonly in mid-and high-rise buildings to resist lateral loads arising from earthquakes and wind forces.To accommodate architectural constraints,facilitate construction,and maximize structural effi-ciency,the majority of these walls have complex configurations,comprising planar and non-planar wall elements that often include regular or irregular patterns of openings.To date most laboratory testing of slender RC walls has employed wall specimens with relatively simple configurations and without openings and coupling action which provides only limited understanding of the impact on performance of the variations in configuration and reinforcement detailing observed in real-world construction.This study presents a 3D continuum modeling approach to improve understanding of the behavior of walls with complex configurations and support recommendations for design of these systems.Planar wall data were used to calibrate the continuum-type modeling approach;experimental data characterizing the response of non-planar walls and walls with openings are used to validate the model.展开更多
High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicle...High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.展开更多
Human exercise performance is influenced by factors related to inherent individual characteristics along with other modifiable factors.During exercise in the heat,sweating provides the major avenue for cooling.When bo...Human exercise performance is influenced by factors related to inherent individual characteristics along with other modifiable factors.During exercise in the heat,sweating provides the major avenue for cooling.When body water losses exceed 2%body mass,changes in physiological responses are observed in a dose-response manner.Human sweat varies in electrolyte content due to differences in ion channel re-absorption in the sweat duct.Moderate hypohydration(>2%body mass)is associated with physical and mental performance impairments,although this depends on the environment(e.g.,warm to hot)and type of exercise(e.g.,endurance)or cognitive task(e.g.,sustained attention,executive function,motor coordination)involved.This begs the question:Is simply adding water the optimal“solution”to improving human performance during events eliciting dehydration?This review focuses on literature applicable to athletes and military personnel during exertion in the heat.Historically,optimally formulating a sports drink to ingest during exercise has focused on appropriate levels of carbohydrate,with more recent interest spanning from higher electrolyte concentrations to amino acid formulations.Evidence to support recommendations regarding beverage bioavailability during exercise comes from studies comparing the appearance of heavy water(tagged within a beverage)in blood.Fluid delivery appears enhanced with moderately concentrated carbohydrate while electrolyte composition plays a lesser role.Despite the robust historical scientific literature related to fluid replacement,the quest for the optimal sports drink during exercise in the heat continues to generate interest considering global warming trends and the increasing numbers of new hydration-related products for exercising individuals.展开更多
Laboratory experiments were conducted in a wave flume on internal solitary wave （ISW） of depression and elevation types propagating over a submarine ridge in semicircular/triangular shape. Tests were arranged in ser...Laboratory experiments were conducted in a wave flume on internal solitary wave （ISW） of depression and elevation types propagating over a submarine ridge in semicircular/triangular shape. Tests were arranged in series for combinations of submarine ridges of different heights and ISW of different amplitudes. The resuhant wave motions were found differing from thee of surface gravity waves. In deeper water, where an ISW of depression-type prevailed, the process of wave breaking displayed downward motion with continuous eddy on the front face of the ridge followed by upward motion towards the apex of the obstacle. Experimental results also suggested that blockage parameter ξ could be applied to classify various degrees of ISW-ridge interaction, i.e., ξ 〈 0.5 for weak interaction, 0.5 〈 ξ 〈 0.7 for moderate interaction, and 0.7 〈 ξ for wave breaking.展开更多
Frequency-tunable microwave signal generation is proposed and experimentally demonstrated with a dual-wavelength single-longitudinal-mode （SLM） erbium-doped fiber ring laser based on a digital Opto-DMD processor and...Frequency-tunable microwave signal generation is proposed and experimentally demonstrated with a dual-wavelength single-longitudinal-mode （SLM） erbium-doped fiber ring laser based on a digital Opto-DMD processor and four-wave mixing （FWM） in a high-nonlinear photonic crystal fiber （PCF）. The high-nonlinear PCF is employed for the generation of the FWM to obtain stable and uniform dual-wavelength oscillation. Two different short passive sub-ring cavities in the main ring cavity serve as mode filters to make SLM lasing. The two lasing wavelengths are electronically selected by loading different gratings on the Opto-DMD processor controlled with a computer. The wavelength spacing can be smartly adjusted from 0.165 nm to 1.08 nm within a tuning accuracy of 0.055 nm. Two microwave signals at 17.23 GHz and 27.47 GHz are achieved. The stability of the microwave signal is discussed. The system has the ability to generate a 137.36-GHz photonic millimeter signal at room temperature.展开更多
Sustainable aviation fuel(SAF)production from biomass and biowaste streams is an attractive option for decarbonizing the aviation sector,one of the most-difficult-to-electrify transportation sectors.Despite ongoing co...Sustainable aviation fuel(SAF)production from biomass and biowaste streams is an attractive option for decarbonizing the aviation sector,one of the most-difficult-to-electrify transportation sectors.Despite ongoing commercialization efforts using ASTM-certified pathways(e.g.,lipid conversion,Fischer-Tropsch synthesis),production capacities are still inadequate due to limited feedstock supply and high production costs.New conversion technologies that utilize lignocellulosic feedstocks are needed to meet these challenges and satisfy the rapidly growing market.Combining bio-and chemo-catalytic approaches can leverage advantages from both methods,i.e.,high product selectivity via biological conversion,and the capability to build C-C chains more efficiently via chemical catalysis.Herein,conversion routes,catalysis,and processes for such pathways are discussed,while key challenges and meaningful R&D opportunities are identified to guide future research activities in the space.Bio-and chemo-catalytic conversion primarily utilize the carbohydrate fraction of lignocellulose,leaving lignin as a waste product.This makes lignin conversion to SAF critical in order to utilize whole biomass,thereby lowering overall production costs while maximizing carbon efficiencies.Thus,lignin valorization strategies are also reviewed herein with vital research areas identified,such as facile lignin depolymerization approaches,highly integrated conversion systems,novel process configurations,and catalysts for the selective cleavage of aryl C-O bonds.The potential efficiency improvements available via integrated conversion steps,such as combined biological and chemo-catalytic routes,along with the use of different parallel pathways,are identified as key to producing all components of a cost-effective,100%SAF.展开更多
The purpose of this paper is to analyze and visualize the exact invariant solution of the nonlinear simplified version of the shallow water equations which are being used to simulate equatorial atmospheric waves of pl...The purpose of this paper is to analyze and visualize the exact invariant solution of the nonlinear simplified version of the shallow water equations which are being used to simulate equatorial atmospheric waves of planetary scales. The method of obtaining the exact solution is based on the Lie group invariance principle. It is shown that the obtained invariant solution has a Fibonacci spiral-like form and has two parameters k and t<sub>0</sub>. We have defined a new model hypermarameter Δ<sub>k</sub>t = t – t<sub>0</sub>, where t is time. The question of particular interest is: can we tune the hypermarameter in order to match the exact solution to the actual Fibonacci spiral? It was discovered that the physically relevant part of the solution matches exactly the Fibonacci spiral.展开更多
基金sponsorship of the National Natural Science Foundation of China (U24B2020,42174139)。
文摘The wave-induced fluid flow(WIFF) occurring in the ubiquitous layered porous media(e.g.,shales)usually causes the appreciable seismic energy dissipation,which further leads to the frequency dependence of wave velocity(i.e.,dispersion) and elastic anisotropy parameters.The relevant knowledge is of great importance for geofluid discrimination and hydrocarbon exploration in the porous shale reservoirs.We derive the wave equations for a periodic layered transversely isotropy medium with a vertical axis of symmetry(VTI) concurrently with the annular cracks(PLPC medium) based on the periodic-layered model and anisotropic Biot's theory,which simultaneously incorporate the effects of microscopic squirt fluid flow,mesoscopic interlayer fluid flow and macroscopic global fluid flow.Notably,the microscopic squirt shorten fluid flow emerges between the annular-shaped cracks and stiff pores,which generates one attenuation peak.Specifically,we first establish the stress-strain relationship and pore fluid pressure in a PLPC medium,and then use them to derive the wave equations by means of the Newton's second law.The plane analysis is implemented on the wave equations to yield the analytic solutions for phase velocities and attenuation factors of four waves,namely,fast P-wave,slow P-wave,SV-wave and SH-wave,and the anisotropy parameters can be therefore computed.Simulation results show that P-wave velocity have three attenuation peaks throughout the full frequency band,which respectively correspond to the influences of interlayer flow,the squirt flow and the Biot flow.Through the results of seismic velocity dispersion and attenuation at different incident angles,we find that the WIFF mechanism also has a significant impact on the dispersion characteristics of elastic anisotropy parameters within the low-mid frequency band.Moreover,it is shown that several poroelastic parameters,such as layer thickness ratio,crack aspect ratio and crack density have notable influence on seismic dispersion and attenuation.We compare the proposed modeled velocities with that given by the existing theory to confirm its validity.Our formulas and result can provide a better understanding of wave propagation in PLPC medium by considering the unified impacts of micro-,meso-and macro-scale WIFF mechanisms,which potentially lays a theoretical basis of rock physics for seismic interpretation.
基金supported by the program for National Natural Science Foundation of China (Nos. 52174173, 52274188, and 52104190)the Joint Funds of the National Natural Science Foundation of China (No. U24A2091)+1 种基金The Natural Science Foundation of Henan Polytechnic University (No. B2021-2)Double FirstClass Initiative of Safety and Energy Engineering (Henan Polytechnic University) (Nos. AQ20240703 and AQ20230304)。
文摘Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure through self-priming. However, their pressure frequency and cavitation characteristics remain unclear, resulting in an inability to fully utilize resonance and cavitation erosion to break coal and rock. In this study, high-frequency pressure testing, high-speed photography, and large eddy simulation(LES) are used to investigate the distribution of the pressure frequency band, evolution law of the cavitation cloud, and its regulation mechanism of a continuous waterjet, SOPW, and AFESOPW. The results indicated that the excitation of the plunger pump, shearing layer vortex, and bubble collapse corresponded to the three high-amplitude frequency bands of the waterjet pressure. AFESOPWs have an additional self-priming frequency that can produce a larger amplitude under a synergistic effect with the second high-amplitude frequency band. A better cavitation effect was produced after self-priming the annulus fluid, and the shedding frequency of the cavitation clouds of the three types of waterjets was linearly related to the cavitation number. The peak pressure of the waterjet and cavitation erosion effect can be improved by modulating the waterjet pressure oscillation frequency and cavitation shedding frequency.
基金Project supported by the National Natural Science Foundation of China(Grant No.12072340)the Chinese Scholarship Council and the Australia Research Council through a linkage project fund。
文摘The successful application of perimeter control of urban traffic system strongly depends on the macroscopic fundamental diagram of the targeted region.Despite intensive studies on the partitioning of urban road networks,the dynamic partitioning of urban regions reflecting the propagation of congestion remains an open question.This paper proposes to partition the network into homogeneous sub-regions based on random walk algorithm.Starting from selected random walkers,the road network is partitioned from the early morning when congestion emerges.A modified Akaike information criterion is defined to find the optimal number of partitions.Region boundary adjustment algorithms are adopted to optimize the partitioning results to further ensure the correlation of partitions.The traffic data of Melbourne city are used to verify the effectiveness of the proposed partitioning method.
文摘Microbial fuel cells(MFCs)are promising for realizing wastewater remediation and electricity co-generation,which may significantly promote the formation of an environmentally friendly,clean energy society.Unfortunately,most of the available MFCs show relatively low electricity generation.Anodes,the major component of MFCs,play the most critical role in electron transfer and organic decomposition,which directly determine the performance of MFCs.In the past decades,various carbonaceous materials and carbon-supported conductive composites have been extensively exploited to optimize the electron transfer on the anode due to their versatile properties,such as large surface area and excellent electrical conductivity.The development of anode materials with a particular structure and performance to satisfy field-scale long-term operation of MFCs remains a huge research challenge,which attracts great attention and urgently needs in-depth exploration of the material engineering of anodes for MFCs.In this review,recent advances in the development and optimization of anodes for MFCs are summarized,and applications of MFCs with advanced anodes in the remediation of different types of wastewater are discussed.Advances of anodes for promoting electron transfer,microbial attachment and organic decomposition are the main focuses.The superiorities of MFCs on different aspects of wastewater remediation are elucidated,along with perspectives on future research of MFCs,aiming to provide useful guidance in related fields.
文摘Background:While muscle contractility increases with muscle temperature,there is no consensus on the best warm-up protocol to use before resistance training or sports exercise due to the range of possible warm-up and testing combinations available.Therefore,the objective of the current study was to determine the effects of different warm-up types(active,exercise-based vs.passive)on muscle function tested using different activation methods(voluntary vs.evoked)and performance test criteria(maximum force vs.rate-dependent contractile properties),with consideration of warm-up task specificity(specific vs.non-specific),temperature measurement method(muscle vs.skin),baseline temperatures,and subject-specific variables(training status and sex).Methods:A systematic search was conducted in PubMed/MEDLINE,Scopus,Web of Science,Cochrane,Embase,and ProQuest.Random-effects meta-analyses and meta-regressions were used to compute the effect sizes(ES)and 95%confidence intervals(95%CIs)to examine the effects of warm-up type,activation method,performance criterion,subject characteristics,and study design on temperature-related performance enhancement.Results:The search yielded 1272 articles,of which 33 met the inclusion criteria(n=921).Increasing temperature positively affected both voluntary(3.7%/℃±1.8%/℃(mean±SD),ES=0.28(95%CI:0.14 to 0.41))and evoked(3.2%/℃±1.5%/℃(mean±SD),ES=0.65(95%CI:0.29 to 1.00))rate-dependent contractile properties(dynamic,fast-velocity force production,and rate of force development(RFD))but not maximum force production(voluntary:-0.2%/℃±0.9%/℃(mean±SD),ES=0.08(95%CI:-0.05 to 0.22);evoked:-0.1%/℃±0.8%/℃(mean±SD),ES=-0.20(95%CI:-0.50 to 0.10)).Active warm-up did not induce greater enhancements in rate-dependent contractile properties(p=0.284),maximum force production(p=0.723),or overall function(pooled,p=0.093)than passive warm-up.Meta-regressions did not reveal a significant effect of study design,temperature measurement method,warm-up task specificity,training status,or sex on the effect of increasing temperature(p>0.05).Conclusion:Increasing muscle temperature significantly enhances rate-dependent contractile function(RFD and muscle power)but not maximum force in both evoked and voluntary contractions.In contrast to expectation,no effects of warm-up modality(active vs.passive)or temperature measurement method(muscle vs.skin)were detected,although insufficient data prevented robust sub-group analyses.
基金funded,in part,by a Ball State University ASPiRE grant.
文摘Older adults are at an increased risk of developing knee osteoarthritis.High internal knee abduction moment during daily activities may elevate the risk of knee osteoarthritis.Incline walking exercise has been found to decrease knee abduction moment in healthy young adults.However,it is unknown if this occurs in healthy older adults.The purpose of this study was to quantify the internal knee abduction moment at different treadmill grades to determine if incline walking could reduce the knee abduction moment in healthy older adults.Twelve healthy older adult males walked on a treadmill at five incline grades(0%,5%,10%,15%,and 20%)at 1.34 m·s^(-1).The primary outcome variable was the internal knee abduction moment.A one-way repeated measures multivariate analysis of variance was performed to determine differences in the dependent variables among incline gradients.Peak knee abduction moment significantly decreased from level walking at all gradients in 10% increments(0%-10%,p<0.001;5%-15%,p<0.002;and 10%-20%,p=0.04).A reduction in knee abduction moment during incline walking could result in decreased knee joint loading on the medial knee compartment.For older adults,who are looking to exercise to improve their health,incline walking may be beneficial to promote lower body strength and cardiovascular ability without inflicting further harm to the aging knee joints.However,because the frontal plane knee joint was of primary interest in this study,further research is needed to determine the effects of incline walking on other joints and in other planes of motion.
基金supported by the National Natural Science Foundation of China(U21A20321 and 22378241)Research Project Supported by Shanxi Scholarship Council of China(2024-015).
文摘Coal is an essential component of global energy;however,the processes of coal mining and utilization produce significant amounts of coal mine goafs,accompanied by coal-based solid wastes and emitted CO_(2),resulting in severe ecological and environmental challenges.In response to this issue,this study pro-poses a novel approach for filling coal mine goafs using cementitious materials prepared by coal-based solid wastes mineralized with CO_(2)(15%in concentration).The CO_(2) sequestration capacities of individual solid wastes are ranked as follows:carbide slag(CS)>red mud(RM)>fly ash(FA).The performance of filling material prepared from composite solid waste(FA-CS-RM)mineralized with CO_(2) meets the filling requirements of goaf.The filling material(F60C20R20)obtained by CO_(2) mineralization was 14.9 MPa in maximum compressive strength,increasing by 32.2%compared to the non-mineralized material.The prepared filling material exhibits excellent CO_(2) sequestration capacity(i.e.,14.4 kg·t^(−1) in maximum amount of CO_(2) sequestration).According to the analysis of carbon sequestration potential,in China,the annual production of FA,CS,and RM is approximately 899,30,and 107 Mt,respectively in the year of 2023.The utilization of FA,CS,and RM individually can achieve carbon emission reductions of 3.42,10.78,and 0.61 Mt,respectively.The composite solid waste(FA-CS-RM)mineralized with CO_(2) can achieve 1.23 Mt in carbon emissions reduction.Additionally,taking Yellow River Basin of China as a case study,the total volume of underground space in coal mine goafs from 2016 to 2030 is estimated at 8.16 Gm3,indicating that this technology can sequester 0.18 Gt of CO_(2).This approach offers a promising solution for large-scale flue gas CO_(2) sequestration,recycling coal-based solid wastes,and remediating coal mine goafs,contributing to green utilization of coal and the emission reduction of carbon.
文摘Future 6G communications will open up opportunities for innovative applications,including Cyber-Physical Systems,edge computing,supporting Industry 5.0,and digital agriculture.While automation is creating efficiencies,it can also create new cyber threats,such as vulnerabilities in trust and malicious node injection.Denialof-Service(DoS)attacks can stop many forms of operations by overwhelming networks and systems with data noise.Current anomaly detection methods require extensive software changes and only detect static threats.Data collection is important for being accurate,but it is often a slow,tedious,and sometimes inefficient process.This paper proposes a new wavelet transformassisted Bayesian deep learning based probabilistic(WT-BDLP)approach tomitigate malicious data injection attacks in 6G edge networks.The proposed approach combines outlier detection based on a Bayesian learning conditional variational autoencoder(Bay-LCVariAE)and traffic pattern analysis based on continuous wavelet transform(CWT).The Bay-LCVariAE framework allows for probabilistic modelling of generative features to facilitate capturing how features of interest change over time,spatially,and for recognition of anomalies.Similarly,CWT allows emphasizing the multi-resolution spectral analysis and permits temporally relevant frequency pattern recognition.Experimental testing showed that the flexibility of the Bayesian probabilistic framework offers a vast improvement in anomaly detection accuracy over existing methods,with a maximum accuracy of 98.21%recognizing anomalies.
文摘Safe waste disposal is necessary to limit the impact of waste on human health and the environment. This paper evaluates the status of solid waste (SW) disposal in the Wa Municipality, Ghana. The study adopted a descriptive research design and applied quantitative and qualitative research methods. 200 questionnaires were administered to two residential areas, each representing high-income, middle-income, and low-income residential dwellings. The study revealed that the majority of the respondents (33.5%) disposed of their SW in open spaces because any collection service did not cover them and those respondents who were covered by a collection service were not satisfied with the collection service due to irregular collection and inconvenient locations of communal collection containers. In addition, all collected SW in the Wa Municipality are openly dumped in illegal dumping sites across the municipality without any form of processing and treatment. The adoption of an integrated solid waste management system could improve SW disposal in the municipality.
基金supported by the National Natural Science Foundation of China(61962016)the Ministry of Science and Technology of China(G2022033002L)+1 种基金National Natural Science Foundation of Guangxi(2022JJA170057)Guangxi Education Department’s Project on Improving the Basic Research Ability of Young and Middleaged Teachers in Universities(2023ky0812,Research on Statistical Network Delay Predictions in Large-scale SDNs).
文摘Accurate early classification of elephant flows(elephants)is important for network management and resource optimization.Elephant models,mainly based on the byte count of flows,can always achieve high accuracy,but not in a time-efficient manner.The time efficiency becomes even worse when the flows to be classified are sampled by flow entry timeout over Software-Defined Networks(SDNs)to achieve a better resource efficiency.This paper addresses this situation by combining co-training and Reinforcement Learning(RL)to enable a closed-loop classification approach that divides the entire classification process into episodes,each involving two elephant models.One predicts elephants and is retrained by a selection of flows automatically labeled online by the other.RL is used to formulate a reward function that estimates the values of the possible actions based on the current states of both models and further adjusts the ratio of flows to be labeled in each phase.Extensive evaluation based on real traffic traces shows that the proposed approach can stably predict elephants using the packets received in the first 10% of their lifetime with an accuracy of over 80%,and using only about 10% more control channel bandwidth than the baseline over the evolved SDNs.
文摘In many areas around the world, wake surfing has been cited as one of the major causes of lakeshore erosion and turbidity. This paper quantifies the impact related to turbidity and erosion with the use of computational fluid dynamics (CFD) of boat wakes in shallow water and the build-up of wind driven waves. The energy, type and direction of the boat’s wake are described quantitatively and a table for predicting wind driven waves over varying fetches, depth and wind speeds is provided. The CFD simulation shows that if a wake surf boat is operated 200 ft from shore and in at least 10 ft of water, the environmental impact is minimal.
文摘In the global south wide range of studies highlight the limitations of the single-modelled public urban water system to meeting the endogenous water preferences of the urban population. Studies also touched on the complementary roles of private water actors to the single-modelled public water supply system in the urban water supply network. Multiple of urban water supply systems （multi-model） co-exist in the urban landscape of global south. However, it is unclear and largely inconclusive on the suitable and satisfactory urban water supply model that meets the water consumption needs of informal settlement dwellers in the global south. This study draws the experiences of households in the informal settlements using a case-study with cross-sectional survey strategy to assess the suitability of the multi-model urban water supply system for sustainable urban water supply in the informal settlements. A total of 292 households were randomly sampled alongside 35 purposively sampled private water actors and public water departments. The data were collected through face to face interviews. Findings show that water supply services of the multi-model water supply system are inevitably suitable for the water consumption needs of informal settlements’s dwellers. The operation of the multi-model water supply system is flexible and able to accommodate the diverse water consumption preferences and choices of the different socio-economic groups in the informal settlements. We observed that multiplicity of urban water supply system increases households’ access to water but does not necessarily improve the quality of water serve in the informal settlements. The paper recommended for the formalisation and adoption of the multi-model urban water supply system to meet the growing demand for improved water supply and services in the informal settlements.
基金supported by the Australian Research Council via Discovery Projects(Nos.DP200103315,DP200103332 and DP230100685)Linkage Projects(No.LP220200920)+1 种基金support from the IONTOF M6 ToF-SIMS(funded by ARC LIEF,LE190100053)the Kratos Axis Ultra XPS(ARC LIEF,LE120100026)。
文摘Ni-rich LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NCM)cathodes in layered oxide cathodes are attractive for high-energy lithium-ion batteries but suffer from rapid capacity fade and thermal instability at high charge voltages.In this study,we propose an entropy-assisted multi-element doping strategy to mitigate these issues.Specifically,two routes are designed and compared:bulk-like localized high-entropy doping(BHE-NCM)and surface-distributed high-entropy-zone doping(SHE-NCM).The surface entropy-doped NCM cathode delivers enhanced electrochemical performance,including higher capacity retention under 4.5 V cycling and superior rate capability,compared to both bulk-like and pristine counterparts.Comprehensive material characterization reveals that surface-localized doping stabilizes the layered structure with reduced microcrack formation and creates a uniform dopant-rich surface region with improved thermal and electrochemical stability.Overall,entropy-assisted doping at the near surface zone effectively alleviates structural degradation and interface reactions in Ni-rich NCM,enabling improved cycling performance at high voltage.This work highlights the significance of surface entropy engineering as a promising strategy for designing high-voltage cathodes with improved safety and longevity.
文摘Slender RC walls are used commonly in mid-and high-rise buildings to resist lateral loads arising from earthquakes and wind forces.To accommodate architectural constraints,facilitate construction,and maximize structural effi-ciency,the majority of these walls have complex configurations,comprising planar and non-planar wall elements that often include regular or irregular patterns of openings.To date most laboratory testing of slender RC walls has employed wall specimens with relatively simple configurations and without openings and coupling action which provides only limited understanding of the impact on performance of the variations in configuration and reinforcement detailing observed in real-world construction.This study presents a 3D continuum modeling approach to improve understanding of the behavior of walls with complex configurations and support recommendations for design of these systems.Planar wall data were used to calibrate the continuum-type modeling approach;experimental data characterizing the response of non-planar walls and walls with openings are used to validate the model.
基金funded by the Department of Energy Office of Vehicle Technologies under the Automotive Lightweighting Materials Program。
文摘High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.
文摘Human exercise performance is influenced by factors related to inherent individual characteristics along with other modifiable factors.During exercise in the heat,sweating provides the major avenue for cooling.When body water losses exceed 2%body mass,changes in physiological responses are observed in a dose-response manner.Human sweat varies in electrolyte content due to differences in ion channel re-absorption in the sweat duct.Moderate hypohydration(>2%body mass)is associated with physical and mental performance impairments,although this depends on the environment(e.g.,warm to hot)and type of exercise(e.g.,endurance)or cognitive task(e.g.,sustained attention,executive function,motor coordination)involved.This begs the question:Is simply adding water the optimal“solution”to improving human performance during events eliciting dehydration?This review focuses on literature applicable to athletes and military personnel during exertion in the heat.Historically,optimally formulating a sports drink to ingest during exercise has focused on appropriate levels of carbohydrate,with more recent interest spanning from higher electrolyte concentrations to amino acid formulations.Evidence to support recommendations regarding beverage bioavailability during exercise comes from studies comparing the appearance of heavy water(tagged within a beverage)in blood.Fluid delivery appears enhanced with moderately concentrated carbohydrate while electrolyte composition plays a lesser role.Despite the robust historical scientific literature related to fluid replacement,the quest for the optimal sports drink during exercise in the heat continues to generate interest considering global warming trends and the increasing numbers of new hydration-related products for exercising individuals.
基金The work was supported bythe National Science Council ,Taiwan,China (Grant No. NSC93-2611-M-110-001)
文摘Laboratory experiments were conducted in a wave flume on internal solitary wave （ISW） of depression and elevation types propagating over a submarine ridge in semicircular/triangular shape. Tests were arranged in series for combinations of submarine ridges of different heights and ISW of different amplitudes. The resuhant wave motions were found differing from thee of surface gravity waves. In deeper water, where an ISW of depression-type prevailed, the process of wave breaking displayed downward motion with continuous eddy on the front face of the ridge followed by upward motion towards the apex of the obstacle. Experimental results also suggested that blockage parameter ξ could be applied to classify various degrees of ISW-ridge interaction, i.e., ξ 〈 0.5 for weak interaction, 0.5 〈 ξ 〈 0.7 for moderate interaction, and 0.7 〈 ξ for wave breaking.
基金supported by the National Basic Research Program of China(Grant No.2010CB327605)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20120005120021)+2 种基金the Fundamental Research Funds for the Central Universities,China(Grant No.2013RC1202)the Program for New Century Excellent Talents in University,China(Grant No.NECT-11-0596)the Beijing Nova Program,China(Grant No.2011066)
文摘Frequency-tunable microwave signal generation is proposed and experimentally demonstrated with a dual-wavelength single-longitudinal-mode （SLM） erbium-doped fiber ring laser based on a digital Opto-DMD processor and four-wave mixing （FWM） in a high-nonlinear photonic crystal fiber （PCF）. The high-nonlinear PCF is employed for the generation of the FWM to obtain stable and uniform dual-wavelength oscillation. Two different short passive sub-ring cavities in the main ring cavity serve as mode filters to make SLM lasing. The two lasing wavelengths are electronically selected by loading different gratings on the Opto-DMD processor controlled with a computer. The wavelength spacing can be smartly adjusted from 0.165 nm to 1.08 nm within a tuning accuracy of 0.055 nm. Two microwave signals at 17.23 GHz and 27.47 GHz are achieved. The stability of the microwave signal is discussed. The system has the ability to generate a 137.36-GHz photonic millimeter signal at room temperature.
基金supported by the Center for Bioenergy Innovation(CBI)supported by the Office of Biological and Environmental Research in the DOE Office of Science and led by Oak Ridge National Laboratory.Oak Ridge National Laboratory is managed by UT-Battelle,LLC for the US DOE under Contract Number DE-AC05-00OR22725+2 种基金authored in part by the Na-tional Renewable Energy Laboratory,operated by Alliance for Sustainable Energy,LLC,for the U.S.Department of Energy(DOE)under Contract No.DE-LC-000L054provided by the U.S.Department of Energy(DOE),Office of Energy Efficiency and Renewable Energy(EERE),and Bioenergy Technologies Office(BETO)at the Pacific Northwest National Laboratory(PNNL)under Contract No.DE-AC05-76RL01830supported by Laboratory Directed Research and Development(LDRD)funding from Argonne National Laboratory,provided by the Director,Office of Science,of the U.S.Department of Energy under Contract No.DE-AC02-06CH11357。
文摘Sustainable aviation fuel(SAF)production from biomass and biowaste streams is an attractive option for decarbonizing the aviation sector,one of the most-difficult-to-electrify transportation sectors.Despite ongoing commercialization efforts using ASTM-certified pathways(e.g.,lipid conversion,Fischer-Tropsch synthesis),production capacities are still inadequate due to limited feedstock supply and high production costs.New conversion technologies that utilize lignocellulosic feedstocks are needed to meet these challenges and satisfy the rapidly growing market.Combining bio-and chemo-catalytic approaches can leverage advantages from both methods,i.e.,high product selectivity via biological conversion,and the capability to build C-C chains more efficiently via chemical catalysis.Herein,conversion routes,catalysis,and processes for such pathways are discussed,while key challenges and meaningful R&D opportunities are identified to guide future research activities in the space.Bio-and chemo-catalytic conversion primarily utilize the carbohydrate fraction of lignocellulose,leaving lignin as a waste product.This makes lignin conversion to SAF critical in order to utilize whole biomass,thereby lowering overall production costs while maximizing carbon efficiencies.Thus,lignin valorization strategies are also reviewed herein with vital research areas identified,such as facile lignin depolymerization approaches,highly integrated conversion systems,novel process configurations,and catalysts for the selective cleavage of aryl C-O bonds.The potential efficiency improvements available via integrated conversion steps,such as combined biological and chemo-catalytic routes,along with the use of different parallel pathways,are identified as key to producing all components of a cost-effective,100%SAF.
文摘The purpose of this paper is to analyze and visualize the exact invariant solution of the nonlinear simplified version of the shallow water equations which are being used to simulate equatorial atmospheric waves of planetary scales. The method of obtaining the exact solution is based on the Lie group invariance principle. It is shown that the obtained invariant solution has a Fibonacci spiral-like form and has two parameters k and t<sub>0</sub>. We have defined a new model hypermarameter Δ<sub>k</sub>t = t – t<sub>0</sub>, where t is time. The question of particular interest is: can we tune the hypermarameter in order to match the exact solution to the actual Fibonacci spiral? It was discovered that the physically relevant part of the solution matches exactly the Fibonacci spiral.
