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Ashtekar-Kodama Gravity as a Classical and Quantum Extension of Loop Quantum Gravity
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作者 Jan Helm 《Journal of Modern Physics》 2024年第6期864-937,共74页
This paper presents a new theory of gravity, called here Ashtekar-Kodama (AK) gravity, which is based on the Ashtekar-Kodama formulation of loop quantum gravity (LQG), yields in the limit the Einstein equations, and i... This paper presents a new theory of gravity, called here Ashtekar-Kodama (AK) gravity, which is based on the Ashtekar-Kodama formulation of loop quantum gravity (LQG), yields in the limit the Einstein equations, and in the quantum regime a full renormalizable quantum gauge field theory. The three fundamental constraints (hamiltonian, gaussian and diffeomorphism) were formulated in 3-dimensional spatial form within LQG in Ashtekar formulation using the notion of the Kodama state with positive cosmological constant Λ. We introduce a 4-dimensional covariant version of the 3-dimensional (spatial) hamiltonian, gaussian and diffeomorphism constraints of LQG. We obtain 32 partial differential equations for the 16 variables E<sub>mn</sub> (E-tensor, inverse densitized tetrad of the metric) and 16 variables A<sub>mn</sub> (A-tensor, gravitational wave tensor). We impose the boundary condition: for large distance the E-generated metric g(E) becomes the GR-metric g (normally Schwarzschild-spacetime). The theory based on these Ashtekar-Kodama (AK) equations, and called in the following Ashtekar-Kodama (AK-) gravity has the following properties. • For Λ = 0 the AK equations become Einstein equations, A-tensor is trivial (constant), and the E-generated metric g(E) is identical with the GR-metric g. • When the AK-equations are developed into a Λ-power series, the Λ-term yields a gravitational wave equation, which has only at least quadrupole wave solutions and becomes in the limit of large distance r the (normal electromagnetic) wave equation. • AK-gravity, as opposed to GR, has no singularity at the horizon: the singularity in the metric becomes a (very high) peak. • AK-gravity has a limit scale of the gravitational quantum region 39 μm, which emerges as the limit scale in the objective wave collapse theory of Gherardi-Rimini-Weber. In the quantum region, the AK-gravity becomes a quantum gauge theory (AK quantum gravity) with the Lie group extended SU(2) = ε-tensor-group(four generators) as gauge group and a corresponding covariant derivative. • AK quantum gravity is fully renormalizable, we derive its Lagrangian, which is dimensionally renormalizable, the normalized one-graviton wave function, the graviton propagator, and demonstrate the calculation of cross-section from Feynman diagrams. 展开更多
关键词 Quantum Gravity Loop Quantum Gravity General Relativity Gravitational Wave Gauge Field Theory Graviton Hamiltonian Constraint Gaussian Constraint Diffeomorphism Constraint
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New Delay Doppler Communication Paradigm in 6G Era:A Survey of Orthogonal Time Frequency Space(OTFS) 被引量:3
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作者 Weijie Yuan Shuangyang Li +4 位作者 Zhiqiang Wei Yuanhao Cui Jiamo Jiang Haijun Zhang Pingzhi Fan 《China Communications》 SCIE CSCD 2023年第6期1-25,共25页
In the 6G era,Space-Air-Ground Integrated Network(SAGIN)are anticipated to deliver global coverage,necessitating support for a diverse array of emerging applications in high-mobility,hostile environments.Under such co... In the 6G era,Space-Air-Ground Integrated Network(SAGIN)are anticipated to deliver global coverage,necessitating support for a diverse array of emerging applications in high-mobility,hostile environments.Under such conditions,conventional orthogonal frequency division multiplexing(OFDM)modulation,widely employed in cellular and Wi-Fi communication systems,experiences performance degradation due to significant Doppler shifts.To overcome this obstacle,a novel twodimensional(2D)modulation approach,namely orthogonal time frequency space(OTFS),has emerged as a key enabler for future high-mobility use cases.Distinctively,OTFS modulates information within the delay-Doppler(DD)domain,as opposed to the timefrequency(TF)domain utilized by OFDM.This offers advantages such as Doppler and delay resilience,reduced signaling latency,a lower peak-to-average ratio(PAPR),and a reduced-complexity implementation.Recent studies further indicate that the direct interplay between information and the physical world in the DD domain positions OTFS as a promising waveform for achieving integrated sensing and communications(ISAC).In this article,we present an in-depth review of OTFS technology in the context of the 6G era,encompassing fundamentals,recent advancements,and future directions.Our objective is to provide a helpful resource for researchers engaged in the field of OTFS. 展开更多
关键词 OTFS 6G delay-Doppler(DD)domain
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Immobilization of Oxyanions on the Reconstructed Heterostructure Evolved from a Bimetallic Oxysulfide for the Promotion of Oxygen Evolution Reaction 被引量:1
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作者 Kai Yu Hongyuan Yang +6 位作者 Hao Zhang Hui Huang Zhaowu Wang Zhenhui Kang Yang Liu Prashanth W.Menezes Ziliang Chen 《Nano-Micro Letters》 SCIE EI CAS CSCD 2023年第10期547-564,共18页
Efficient and durable oxygen evolution reaction(OER)requires the electrocatalyst to bear abundant active sites,optimized electronic structure as well as robust component and mechanical stability.Herein,a bimetallic la... Efficient and durable oxygen evolution reaction(OER)requires the electrocatalyst to bear abundant active sites,optimized electronic structure as well as robust component and mechanical stability.Herein,a bimetallic lanthanum-nickel oxysulfide with rich oxygen vacancies based on the La_(2)O_(2)S prototype is fabricated as a binder-free precatalyst for alkaline OER.The combination of advanced in situ and ex situ characterizations with theoretical calculation uncovers the synergistic effect among La,Ni,O,and S species during OER,which assures the adsorption and stabilization of the oxyanion SO_(4)^(2-)onto the surface of the deeply reconstructed porous heterostructure composed of confining Ni OOH nanodomains by La(OH)_3 barrier.Such coupling,confinement,porosity and immobilization enable notable improvement in active site accessibility,phase stability,mass diffusion capability and the intrinsic Gibbs free energy of oxygen-containing intermediates.The optimized electrocatalyst delivers exceptional alkaline OER activity and durability,outperforming most of the Ni-based benchmark OER electrocatalysts. 展开更多
关键词 Lanthanum-nickel oxysulfide Rare earth metal Immobilization of oxyanions Structural reconstruction Oxygen evolution catalysis
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Fixed-time group consensus of second-order multi-agent systems based on event-triggered control
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作者 武肖帅 孙凤兰 +1 位作者 朱伟 Jürgen Kurths 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第7期329-336,共8页
The problem of fixed-time group consensus for second-order multi-agent systems with disturbances is investigated.For cooperative-competitive network,two different control protocols,fixed-time group consensus and fixed... The problem of fixed-time group consensus for second-order multi-agent systems with disturbances is investigated.For cooperative-competitive network,two different control protocols,fixed-time group consensus and fixed-time eventtriggered group consensus,are designed.It is demonstrated that there is no Zeno behavior under the designed eventtriggered control.Meanwhile,it is proved that for an arbitrary initial state of the system,group consensus within the settling time could be obtained under the proposed control protocols by using matrix analysis and graph theory.Finally,a series of numerical examples are propounded to illustrate the performance of the proposed control protocol. 展开更多
关键词 event-triggered control group consensus multi-agent system fixed-time
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Elucidating the clinical and immunological value of m6A regulatormediated methylation modification patterns in adrenocortical carcinoma
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作者 WENHAO XU HAOMING LI +8 位作者 YASIR HAMEED MOSTAFA A.ABDEL-MAKSOUD SAEEDAH MUSAED ALMUTAIRI AYMAN MUBARAK MOHAMMED AUFY WAEL ALTURAIKI ABDULAZIZ J.ALSHALANI AYMAN M.MAHMOUD CHEN LI 《Oncology Research》 SCIE 2023年第5期819-831,共13页
N6-methyladenosine methylation(m6A)is a common type of epigenetic alteration that prominently affects the prognosis of tumor patients.However,it is unknown how the m6A regulator affects the tumor microenvironment(TME)... N6-methyladenosine methylation(m6A)is a common type of epigenetic alteration that prominently affects the prognosis of tumor patients.However,it is unknown how the m6A regulator affects the tumor microenvironment(TME)cell infiltration in adrenocortical carcinoma(ACC)and how it affects the prognosis of ACC patients yet.The m6A alteration patterns of 112 ACC patients were evaluated,furthermore,the association with immune infiltration cell features was investigated.The unsupervised clustering method was applied to typify the m6A alteration patterns of ACC patients.The principal component analysis(PCA)technique was taken to create the m6A score to assess the alteration pattern in specific malignancies.We found two independent patterns of m6A alteration in ACC patients.The TME cell infiltration features were significantly in accordance with phenotypes of tumor immune-inflamed and immune desert in both patterns.The m6Ascore also served as an independent predictive factor in ACC patients.The somatic copy number variation(CNV)and patients prognosis can be predicted by m6A alteration patterns.Moreover,the ACC patients with high m6A scores had better overall survival(OS)and higher efficiency in immune checkpoint blockade therapy.Our work demonstrated the significance of m6A alteration to the ACC patients immunotherapy.The individual m6A alteration patterns analysis might contribute to ACC patients prognosis prediction and immunotherapy choice. 展开更多
关键词 m6A Tumor microenvironment Adrenocortical carcinoma IMMUNOTHERAPY PROGNOSIS
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Evaluation of the Relation between Cognitive Science and Embodied Cognition
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作者 Elham Shirvani Masoud Shirvani 《World Journal of Neuroscience》 2023年第4期210-227,共18页
This article delves into the intricate relationship between cognitive science and embodied cognition, offering transformative philosophical insights with profound implications for our understanding of the mind-body co... This article delves into the intricate relationship between cognitive science and embodied cognition, offering transformative philosophical insights with profound implications for our understanding of the mind-body connection. In response to the journal’s feedback, we have enhanced the abstract to provide a more comprehensive overview of our study. Background: We trace the historical evolution of ideas, from the inception of cognitive science rooted in analytic philosophy to the groundbreaking contributions of Rodney Brooks and others in the field of artificial intelligence. We also explore the work of scholars such as Agre, Chapman, and Dreyfus, shedding light on the role of cognitive metaphor and the concept of the cognitive unconscious in shaping our understanding of embodied cognition. Purpose: Our study aims to shed light on the central theme that unites these various strands of thought—the rejection of the traditional, transcendental view of the subject in favor of the concept of an embodied subject. This embodied subject actively engages with its environment, shaping consciousness and cognition. This shift in perspective challenges classical epistemological theories and opens new avenues for inquiry. Method: We have conducted a comprehensive literature review to explore the historical development and key concepts in the field of embodied cognition, with a particular focus on the philosophical underpinnings and their integration into cognitive science. Results: Our examination of embodied cognition reveals that the mind is intimately connected to the body, with cognition emerging through interactions with the environment and perceptual experiences. This perspective challenges reductionist notions and demonstrates that mental states cannot be reduced to brain states alone. We also explore the relationship between functionalism and computational states of the brain, illustrating that mental states can be understood in the context of mathematical functions. Conclusion: In conclusion, this paper highlights the profound implications of embodied cognition and suggests that the mind is not isolated from the body but intimately tied to it. This perspective provides a fresh approach to the mind-body problem, emphasizing the role of the environment and perceptual experiences in shaping cognition. We invite further research into the practical applications of embodied cognition in fields like artificial intelligence, robotics, and psychology, and encourage investigations into the intersections between cognitive science and various branches of philosophy, offering valuable insights into the nature of consciousness and cognition. In essence, this study provides a comprehensive overview of the evolution and implications of embodied cognition, laying the groundwork for further research and fostering a deeper appreciation of the profound shifts in perspective that this theory brings to our understanding of the human mind. 展开更多
关键词 Cognitive Science Embodied Cognition Artificial Intelligence
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QSAR Studies on the Toxicity of Nitrobenzenes to Population Growth of Tetrahymena Pyriformis 被引量:9
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作者 XU Jing-bo JING Ti-song +1 位作者 Pauli W. Berger S. 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2002年第3期258-261,共4页
The IGC 50 (50% inhibitory growth concentration) values of 27 nitrobenzenes were determined for the population growth endpoint of Tetrahymena pyriformis . The toxicity order of the observed compounds was found to be a... The IGC 50 (50% inhibitory growth concentration) values of 27 nitrobenzenes were determined for the population growth endpoint of Tetrahymena pyriformis . The toxicity order of the observed compounds was found to be as follows: dinitro compounds>mononitro compounds, dichloronitrobenzenes>monochloronitrobenzenes, meta substituted nitrobenzenes>ortho /para substituted nitrobenzenes(NT, NPh, NAnis) except for the dinitrobenzenes and nitroanilines(DNB, NAn). Quantitative structure activity relationships(QSARs) were developed with the logarithm of the reciprocal of IGC 50 [lg(IGC 50 ) -1 ] in mole liter as dependent variable and six molecular descriptors lg P , 1 X Ⅴ, I, 1K a, ∑σ - and E LUMO as independent variables. Via multiple regression analysis, one best equation was obtained: lg(IGC 50 ) -1 =3.029+0.860∑ σ -+0.341I n=27, r=0.924, r 2=0.854, s=0.265, f=70.44 , Pr> f =0.000 1 The equation was used to estimate IGC 50 for five analogues. 展开更多
关键词 Tetrahymena pyriformis NITROBENZENE QSAR
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Stable single-mode operation of 894.6 nm VCSEL at high temperatures for Cs atomic sensing 被引量:3
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作者 向磊 张星 +3 位作者 张建伟 宁永强 Werner Hofmann 王立军 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第7期130-133,共4页
In this paper, stable single-mode operation at high temperatures is produced by the surface-relief-integrated vertical cavity surface emitting laser(VCSEL). The gain-cavity mode detuning technique is employed to rea... In this paper, stable single-mode operation at high temperatures is produced by the surface-relief-integrated vertical cavity surface emitting laser(VCSEL). The gain-cavity mode detuning technique is employed to realize high operating temperatures for the VCSEL. The surface relief is etched in the centre of the top side as a mode discriminator for the fundamental mode output, and the threshold current minimum is 1.94 mA at high temperatures by the gain-cavity mode detuning technique. Maximum single-fundamental-mode output power of 0.45 mW at 80℃ is obtained, and the side mode suppression ratios(SMSRs) are more than 30 dB with increasing temperature and current, respectively. 展开更多
关键词 single-mode operation surface relief gain-cavity mode detuning vertical cavity surface emitting laser(VCSEL)
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Soil Properties in Two Soil Profiles from Terraces of the Nam Co Lake in Tibet,China 被引量:3
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作者 WANG Liqiang YI Chaolu +2 位作者 Brigitta Sehiitt LIU Kexin ZHOU Liping 《Journal of Mountain Science》 SCIE CSCD 2009年第4期354-361,共8页
This article investigates the soil properties in two soil profiles from the terraces of the Nam Co Lake in Tibet,China. Profile 1,with a slope aspect to east,is 37 m,and profile 2,to southwest,is 32 m above the lake l... This article investigates the soil properties in two soil profiles from the terraces of the Nam Co Lake in Tibet,China. Profile 1,with a slope aspect to east,is 37 m,and profile 2,to southwest,is 32 m above the lake level. Twelve and nine layers were identified in profile 1 and profile 2,respectively,based on the color,texture,structure,moisture content,presence of carbonate,and root density. Grain sizes and measurements of water content,total organic carbon,total inorganic carbon,total carbon,pH value and electrical conductivity were all analyzed for each sample. The results show that soil is poorly developed because of sparse vegetation coverage and weak chemical weathering in the cold and arid area. The results also indicate that the soil properties are different between the two profiles and suggest that soil is better developed in profile 1 than in profile 2. These differences are ascribed to the dissimilarity of landform,vegetation and timing. Profile 1 faces to east as compared with profile 2 facing to southwest and gets less insolation and therefore less evaporation. Thus,vegetation grows better in profile 1 than in profile 2. Radiocarbon dating and OSL dating show that profile 1 underwent a longer soil forming process than profile 2,which is helpful for the soil development in profile 1. 展开更多
关键词 土壤性质 纳木错 西藏 梯田 中国 配置文件 植被覆盖度 土壤剖面
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Graptolite, Chitinozoan and Scolecodont Reflectances and Their Use as Indicators of Thermal Maturity 被引量:2
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作者 Andreas Hoffknecht Rainer Bainer Brocke Bernd-D. Erdtmann 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1993年第1期93-105,125-126,共15页
Based on studies of the reflectance of Ordovician and Silurian zooclasts from 11 sections around the Huangling Anticline, Hubei, China, combined with determination of the conodont colour alteration indices (CAI) and o... Based on studies of the reflectance of Ordovician and Silurian zooclasts from 11 sections around the Huangling Anticline, Hubei, China, combined with determination of the conodont colour alteration indices (CAI) and of infrared spectroscopy of dispersed organic matter from the same or adjacent horizons, it is further proved that reflectances of graptolites, chitinozoans and scolecldonts, like vitrinite and natural bitumen, increase with increasing maturation, but follow different reflectance paths. They may be used, therefore, as thermal maturation indicators. Graptolites display optically strong anisotropy. The maximum reflectance measured from graptolite on polished section cut parallel to the bedding plane is the most suitable for determination of maturation of their host rocks. In polished section chitinozoan and scolecodont show reflectance, but no bireflectance owing to their isotropy. The random reflectance of chitinozoans is higher than that of scolecodonts in the case of the same maturity. By analysing the distribution trends of graptolite, chitionzoan and scolecodont reflectances, the Ordovician and Silurian strata can be subdivided into three areas of maturation in the present region. The potential of oil or gas generation is discussed for each area. The result is basically coincident with the distribution pattern of regional organic maturation presented by CAI and infrared spectroscopic determination of organic matter. 展开更多
关键词 GRAPTOLITE CHITINOZOAN scolecodont reflectance
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Characterization of Aquabacterium parvum sp. Strain B6 during Nitrate-Dependent Fe(Ⅱ) Oxidation Batch Cultivation with Various Impact Factors 被引量:2
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作者 Xiaoxin Zhang Ulrich Szewzyk Fang Ma 《Transactions of Tianjin University》 EI CAS 2017年第4期315-324,共10页
In order to assess the capacity of Aquabacterium parvum sp. strain B6 for nitrate-dependent Fe(Ⅱ) oxidation,batch cultivation was conducted, and its ability to oxidize Fe(Ⅱ) coupled to nitrate reduction in the prese... In order to assess the capacity of Aquabacterium parvum sp. strain B6 for nitrate-dependent Fe(Ⅱ) oxidation,batch cultivation was conducted, and its ability to oxidize Fe(Ⅱ) coupled to nitrate reduction in the presence of diverse organic substrates was studied. Meanwhile, the nitrate-removal rate of B6 with various impact factors was further optimized by the response surface methodology(RSM). The results show that strain B6 is capable of utilizing different organic compounds as substrates for nitrate reduction. Compared with yeast extract, B6 showed a greater potential of chemical oxygen demand(COD)degradation and cell proliferation with acetate and glucose mediums, respectively, while citrate was not beneficial for this process due to its low consumption rate. RSM analysis demonstrated that the maximum nitrate-reduction rate of 30.64% could be achieved with an initial pH of 7.4,incubation temperature of 25.0 °C, and carbon source concentration of 266.10 mg/L. 展开更多
关键词 Nitrate-dependent FE(II) OXIDATION NITRATE reduction Impact factors Optimization Aquabacteria
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Rotary-scaling fine-tuning (RSFT) method for optimizing railway wheel profiles and its application to a locomotive 被引量:7
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作者 Yunguang Ye Yayun Qi +3 位作者 Dachuan Shi Yu Sun Yichang Zhou Markus Hecht 《Railway Engineering Science》 2020年第2期160-183,共24页
The existing multi-objective wheel profile optimization methods mainly consist of three sub-modules:(1)wheel profile generation,(2)multi-body dynamics simulation,and(3)an optimization algorithm.For the first module,a ... The existing multi-objective wheel profile optimization methods mainly consist of three sub-modules:(1)wheel profile generation,(2)multi-body dynamics simulation,and(3)an optimization algorithm.For the first module,a comparably conservative rotary-scaling finetuning(RSFT)method,which introduces two design variables and an empirical formula,is proposed to fine-tune the traditional wheel profiles for improving their engineering applicability.For the second module,for the TRAXX locomotives serving on the Blankenburg–Rubeland line,an optimization function representing the relationship between the wheel profile and the wheel–rail wear number is established based on Kriging surrogate model(KSM).For the third module,a method combining the regression capability of KSM with the iterative computing power of particle swarm optimization(PSO)is proposed to quickly and reliably implement the task of optimizing wheel profiles.Finally,with the RSFT–KSM–PSO method,we propose two wear-resistant wheel profiles for the TRAXX locomotives serving on the Blankenburg–Rubeland line,namely S1002-S and S1002-M.The S1002-S profile minimizes the total wear number by 30%,while the S1002-M profile makes the wear distribution more uniform through a proper sacrifice of the tread wear number,and the total wear number is reduced by 21%.The quasi-static and hunting stability tests further demonstrate that the profile designed by the RSFT–KSM–PSO method is promising for practical engineering applications. 展开更多
关键词 Wheel profile optimization Wear reduction Rotary-scaling fine-tuning Particle swarm optimization Kriging surrogate model
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Railway wheel profile fine-tuning system for profile recommendation 被引量:3
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作者 Yunguang Ye Jonas Vuitton +1 位作者 Yu Sun Markus Hecht 《Railway Engineering Science》 2021年第1期74-93,共20页
This paper develops a wheel profile fine-tuning system(WPFTS)that comprehensively considers the influence of wheel profile on wheel damage,vehicle stability,vehicle safety,and passenger comfort.WPFTS can recommend one... This paper develops a wheel profile fine-tuning system(WPFTS)that comprehensively considers the influence of wheel profile on wheel damage,vehicle stability,vehicle safety,and passenger comfort.WPFTS can recommend one or more optimized wheel profiles according to train operators’needs,e.g.,reducing wheel wear,mitigating the development of wheel out-of-roundness(OOR),improving the shape stability of the wheel profile.Specifically,WPFTS includes four modules:(I)a wheel profile generation module based on the rotary-scaling finetuning(RSFT)method;(II)a multi-objective generation module consisting of a rigid multi-body dynamics simulation(MBS)model,an analytical model,and a rigid–flexible MBS model,for generating 11 objectives related to wheel damage,vehicle stability,vehicle safety,and passenger comfort;(III)a weight assignment module consisting of an adaptive weight assignment strategy and a manual weight assignment strategy;and(IV)an optimization module based on radial basis function(RBF)and particle swarm optimization(PSO).Finally,three cases are introduced to show how WPTFS recommends a wheel profile according to train operators’needs.Among them,a wheel profile with high shape stability,a wheel profile for mitigating the development of wheel OOR,and a wheel profile considering hunting stability and derailment safety are developed,respectively. 展开更多
关键词 Wheel profile fine-tuning system Optimization RECOMMENDATION WEAR Contact concentration index Multi-body dynamics simulation(MBS) Railway wheel
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Breakage of drops and bubbles in a stirred tank: A review ofexperimental studies 被引量:1
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作者 Basim O. Hasan 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第6期698-711,共14页
The rate of breakage of drops and bubbles(fluid particles) in stirred systems is of great consequence on mass,heat, and momentum transport phenomena. Therefore, over the years, the topic has gained a considerable atte... The rate of breakage of drops and bubbles(fluid particles) in stirred systems is of great consequence on mass,heat, and momentum transport phenomena. Therefore, over the years, the topic has gained a considerable attention from the researchers to study and characterize this phenomenon. In present work, the experimental studies of breakage phenomenon in a stirred tank in the last four decades were reviewed. The review highlighted the investigated experimental conditions and the major findings concerning the breakage mechanism and the effect of operating conditions. The discrepancy and contradictions of the outcomes of those studies were specified and discussed. Experimental observations and conclusions concerning the breakage characterization parameters,such as deformation, breakage probability, breakage time, and breakage location were presented and commented on. Possible future refinements and prospective were recommended. The review indicated that there are clear discrepancies and contradictions between previous studies regarding the effect of some operating parameters and the values of breakage time, breakage probability, number of daughter particles, and breakage location relative to the impeller. In addition, there are still many scientific gaps that need to be studied and characterized in future by overcoming specific experimental difficulties and uncertainties. 展开更多
关键词 DROP BUBBLE BREAKAGE Stirred TANK Review BREAKAGE RATE
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Determinants of Farmers’ Perception of Climate Change: A Case Study from the Coastal Region of Bangladesh 被引量:3
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作者 Mohammed Nasir Uddin Wolfgang Bokelmann Emily Shea Dunn 《American Journal of Climate Change》 2017年第1期151-165,共15页
Socio-economic conditions of farmers, especially in the coastal region in Bangladesh, have been severely affected because of climate change. This study was focused on analyzing the farmers’ perception of climate chan... Socio-economic conditions of farmers, especially in the coastal region in Bangladesh, have been severely affected because of climate change. This study was focused on analyzing the farmers’ perception of climate change by examining three vital issues: (1) description of the socioeconomic characteristics of farmers;(2) reporting on the perception of farmers experiences with climatic change;and (3) identification of the socio-economic factors associated with farmers’ perception of climate change. The study area encompasses three villages within the coastal region (Sathkhira district) of Bangladesh, a geographic region where climate change literature has highlighted as prone to accelerated degradation. A logit model, along with weighted indexes for ranking and descriptive statistics, was used to analyze the result of 100 farmers surveyed by questionnaire. We found that the majority of the farmers (88%) perceived changes in climatic conditions. Almost all farmers indicated increases in temperature, droughts, floods, cyclones, salinity level and decreasing rainfall over the last 20 years. The logit model explained that out of the nine factors surveyed;education, family size, farm size, family income, farming experiences and training received were significantly related and influential factors to perception of climate change. Therefore, government and non-governmental organizations are recommended to push forward with interventions, especially focusing on identified factors, in order to strengthen the farmers’ capacity to battle against climate change effects. 展开更多
关键词 Determinants FARMERS PERCEPTION CLIMATE Change COASTAL Region BANGLADESH
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Geology of Mars after the first 40 years of exploration 被引量:2
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作者 Angelo Pio Rossi Stephan van Gasselt 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2010年第7期621-652,共32页
The knowledge of Martian geology has increased enormously in the last 40 yr. Several missions orbiting or roving Mars have revolutionized our understanding of its evolution and geological features, which in several wa... The knowledge of Martian geology has increased enormously in the last 40 yr. Several missions orbiting or roving Mars have revolutionized our understanding of its evolution and geological features, which in several ways are similar to Earth, but are extremely different in many respects. The impressive dichotomy between the two Martian hemispheres is most likely linked to its impact cratering history, rather than internal dynamics such as on Earth. Mars' volcanism has been extensive, very longlived and rather constant in its setting. Water was available in large quantities in the distant past of Mars, when a magnetic field and more vigorous tectonics were active. Exogenic forces have been shaping Martian landscapes and have led to a plethora of landscapes shaped by wind, water and ice. Mars' dynamical behavior continues, with its climatic variation affecting climate and geology until very recent times. This paper tries to summarize major highlights in Mars' Geology, and points to deeper and more extensive sources of important scientific contributions and future exploration. 展开更多
关键词 planets and satellites Mars -- Geology -- surface processes -- interior processes
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Deep learning-based fault diagnostic network of high-speed train secondary suspension systems for immunity to track irregularities and wheel wear 被引量:1
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作者 Yunguang Ye Ping Huang Yongxiang Zhang 《Railway Engineering Science》 2022年第1期96-116,共21页
Fault detection and isolation of high-speed train suspension systems is of critical importance to guarantee train running safety. Firstly, the existing methods concerning fault detection or isolation of train suspensi... Fault detection and isolation of high-speed train suspension systems is of critical importance to guarantee train running safety. Firstly, the existing methods concerning fault detection or isolation of train suspension systems are briefly reviewed and divided into two categories, i.e., model-based and data-driven approaches. The advantages and disadvantages of these two categories of approaches are briefly summarized. Secondly, a 1D convolution network-based fault diagnostic method for highspeed train suspension systems is designed. To improve the robustness of the method, a Gaussian white noise strategy(GWN-strategy) for immunity to track irregularities and an edge sample training strategy(EST-strategy) for immunity to wheel wear are proposed. The whole network is called GWN-EST-1 DCNN method. Thirdly, to show the performance of this method, a multibody dynamics simulation model of a high-speed train is built to generate the lateral acceleration of a bogie frame corresponding to different track irregularities, wheel profiles, and secondary suspension faults. The simulated signals are then inputted into the diagnostic network, and the results show the correctness and superiority of the GWN-EST-1DCNN method. Finally,the 1DCNN method is further validated using tracking data of a CRH3 train running on a high-speed railway line. 展开更多
关键词 High-speed train suspension system Fault diagnosis Track irregularities Wheel wear Deep learning Literature review
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Monitoring of Temporal and Spatial Changes of Land Use and Land Cover in Metropolitan Regions through Remote Sensing and GIS 被引量:1
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作者 Mohamed Ali Mohamed 《Natural Resources》 2017年第5期353-369,共17页
The use of remote sensing techniques and subsequent analysis by means of geographical information system (GIS) offers an effective method for monitoring temporal and spatial changes of landscapes. This work studies th... The use of remote sensing techniques and subsequent analysis by means of geographical information system (GIS) offers an effective method for monitoring temporal and spatial changes of landscapes. This work studies the urbanization processes and associated threats to natural ecosystems and resources in the metropolitan areas of Berlin and Erlangen-Fürth-Nürnber?Schwabach (EFNS). To compute the land use/cover (LULC) of the study areas, a supervised classification of “maximum likelihood” using Landsat data for the years of 1972, 1985, 1998, 2003, and 2015 is used. Results show that the built-up area is the dominant land use in both regions throughout the study period. This land use has increased at the expense of green and open areas in EFNS and at the expense of agricultural land in Berlin. Likewise, 5% of forest in EFNS is replaced with urban infrastructure. However, the amount of forest in Berlin increased by 3%. While EFNS experienced relatively big changes in its water bodies from 1972 to 1985, changes in water bodies in Berlin were rather slight during the last 40 years. The overall accuracy of our remotely sensed LULC maps was between 88% and 94% in Berlin and between 85.87% and 87.4% for EFNS. The combination of remote sensing and GIS appears to be an indispensable tool for monitoring changes in LULC in urban areas and help improving LU planning to avoid environmental and ecological problems. 展开更多
关键词 LAND Use CHANGE CHANGE Detection REMOTE Sensing GIS METROPOLIS City METROPOLITAN Region
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Effects of broccoli extract and various essential oils on intestinal and faecal microflora and on xenobiotic enzymes and the antioxidant system of piglets 被引量:1
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作者 Kristin Mueller Nicole M. Blum +5 位作者 Holger Kluge Rolf Bauerfeind Julia Froehlich Anneluise Mader Karola R. Wendler Andreas S. Mueller 《Open Journal of Animal Sciences》 2012年第2期78-98,共21页
Objective: Since the ban of antibiotics as growth promoting feed additives in the EU in 2006 research in alternatives has gained importance. Phytogenic feed additives represent a heterogenous class of different plant ... Objective: Since the ban of antibiotics as growth promoting feed additives in the EU in 2006 research in alternatives has gained importance. Phytogenic feed additives represent a heterogenous class of different plant derived substances that are discussed to improve the health of farm animals by direct and indirect antioxidant effects and by influencing microbial eubiosis in the gastrointestinal tract. Consequently our study aimed to investigate the influence of broccoli extract and the essential oils of tur- meric, oregano, thyme and rosemary, as selected individual additives, on intestinal and faecal microflora, on xenobiotic enzymes, and on the antioxidant system of piglets. Methods: 48 four weeks old male weaned piglets were assigned to 6 groups of 8. The piglets were housed individually in stainless steel pens with slatted floor. The control group (Con) was fed a diet without an additive for 4 weeks. The diet of group BE contained 0.15 g/kg sulforaphane in form of a broccoli extract. 535, 282, 373 and 476 mg/kg of the essential oils of turmeric (Cuo), oregano (Oo), thyme (To) and rosemary (Ro) were added to the diets of the remaining 4 groups to stan-dardise supplementation to 150 mg/kg of the oils’ key terpene compounds ar-turmerone, carvacrol, thymol and 1,8-cineole. The composition of bacterial microflora was examined by cultivating samples of jejeunal and colonic mucosa and of faeces under specific conditions. The mRNA expression of xenobiotic and antioxidant enzymes was determined by reversing transcrip- tase real time detection PCR (RT-PCR). Total antioxidant status was assayed using the Trolox Equivalent Antioxidant Capacity (TEAC), and lipid peroxidation was determined by measuring thiobarbioturic acid reactive substances (TBA- RS). Results: Compared to Con piglets all additives positively influenced weight gain and feed conversion in week 1. Over the whole trial period no significant differences in performance parameters existed between the experimental groups. Compared to group Con performance of Ro piglets was, however, slightly impaired. Com- pared to Con piglets Cuo, Oo and To increased the ratio of Lactobacilli:E. coli attached to the jejunal mucosa, whereas BE and Ro impaired this ratio slightly. In contrast in colonic mucosa Ro improved Lactobacilli:E. coli ratio. In faecal samples an improvement of Lactobacilli:E. coli ratio could be analysed for To and Ro. Ro was the only additive that reduced the incidence rate of piglets tested positive for enterotoxic E. coli (ETEC). All additives significantly increased jejunal TEAC and reduced TBA-RS. In the liver BE, Cuo, Oo and To increased TEAC in tendency and Ro significantly. Liver TBA-RS were slightly reduced by all additives compared to Con piglets. Whereas the influence of BE, To and Ro on jejunal TEAC mainly was derived from the induction of xenobiotic and antioxidant enzymes (indirect antioxidant effects), Cuo and Oo influenced TEAC by direct antioxidant effects. Discussion and Conclusions: Our results have shown: That within the labiatae oils Oo and To have the potential to improve performance slightly. That phytogenic substances have a small but not sig- nificant influence on intestinal microflora. That phytogenic feed additives up-regulate the anti- oxidant system of piglets either by direct or by indirect antioxidant effects and that they may thereby improve health status. That within the labiatae oils Oo has a high direct antioxidant potential whereas Ro potently induces xenobiotic and antioxidant enzymes. That broccoli extract is an attractive new phytogenic additive, improving antioxidant status by indirect antioxidant effects. That defined combinations of selected phytogenic substances may produce additive effects. That health promoting effects of phytogenic additives in the future should be studied systematically under the challenge with pathogenic microorganisms or food derived to-xins. 展开更多
关键词 Pigs Phytogenic Feed Additives BROCCOLI Extract Essential Oils XENOBIOTIC ENZYMES Antioxidant System
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Data-Driven Discovery of Stochastic Differential Equations 被引量:1
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作者 Yasen Wang Huazhen Fang +12 位作者 Junyang Jin Guijun Ma Xin He Xing Dai Zuogong Yue Cheng Cheng Hai-Tao Zhang Donglin Pu Dongrui Wu Ye Yuan Jorge Gonçalves Jürgen Kurths Han Ding 《Engineering》 SCIE EI CAS 2022年第10期244-252,共9页
Stochastic differential equations(SDEs)are mathematical models that are widely used to describe complex processes or phenomena perturbed by random noise from different sources.The identification of SDEs governing a sy... Stochastic differential equations(SDEs)are mathematical models that are widely used to describe complex processes or phenomena perturbed by random noise from different sources.The identification of SDEs governing a system is often a challenge because of the inherent strong stochasticity of data and the complexity of the system’s dynamics.The practical utility of existing parametric approaches for identifying SDEs is usually limited by insufficient data resources.This study presents a novel framework for identifying SDEs by leveraging the sparse Bayesian learning(SBL)technique to search for a parsimonious,yet physically necessary representation from the space of candidate basis functions.More importantly,we use the analytical tractability of SBL to develop an efficient way to formulate the linear regression problem for the discovery of SDEs that requires considerably less time-series data.The effectiveness of the proposed framework is demonstrated using real data on stock and oil prices,bearing variation,and wind speed,as well as simulated data on well-known stochastic dynamical systems,including the generalized Wiener process and Langevin equation.This framework aims to assist specialists in extracting stochastic mathematical models from random phenomena in the natural sciences,economics,and engineering fields for analysis,prediction,and decision making. 展开更多
关键词 Data-driven method System identification Sparse Bayesian learning Stochastic differential equations Random phenomena
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