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Quantifying the natural growth rate of hepatocellular carcinoma:A real-world retrospective study in southwestern China
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作者 Li Tu Hong Xie +6 位作者 Qi Li Ping-Gui Lei Pei-Ling Zhao Fan Yang Chi Gong Yuan-Lin Yao Shi Zhou 《World Journal of Hepatology》 2024年第5期800-808,共9页
BACKGROUND In recent years,approximately half of the newly diagnosed cases and mortalities attributed to hepatocellular carcinoma(HCC)have been reported in China.Despite the high incidence of HCC,there remains a pauci... BACKGROUND In recent years,approximately half of the newly diagnosed cases and mortalities attributed to hepatocellular carcinoma(HCC)have been reported in China.Despite the high incidence of HCC,there remains a paucity of data regarding the natural growth pattern and the determination of optimal surveillance intervals specific to the Chinese population.AIM To quantify the natural tumor growth pattern of HCC in regional China.METHODS A retrospective analysis was performed on patients from a single institution in Southwest China who had undergone two or more serial dynamic computed tomography or magnetic resonance imaging scans between 2014 and 2020,without having received any anti-cancer therapy.Tumor growth was assessed using tumor volume doubling time(TVDT)and tumor growth rate(TGR),with volumes measured manually by experienced radiologists.Simple univariate linear regression and descriptive analysis were applied to explore associations between growth rates and clinical factors.RESULTS This study identifies the median TVDT for HCC as 163.4 d,interquartile range(IQR)72.1 to 302.3 d,with a daily TGR of 0.42%(IQR 0.206%-0.97%).HCC growth patterns reveal that about one-third of tumors grow indolently with TVDT exceeding 270 d,another one-third of tumors exhibit rapid growth with TVDT under 90 d,and the remaining tumors show intermediate growth rates,with TVDT ranging between 3 to 9 months.CONCLUSION The identified TGRs support biannual surveillance and follow-up for HCC patients in certain regions of China.Given the observed heterogeneity in HCC growth,further investigation is warranted. 展开更多
关键词 Hepatocellular carcinoma Natural tumor growth pattern Tumor volume doubling time Tumor growth rate Realworld retrospective study
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Values of the Times of Marx's Theory of Science and Technology Progress and Utilization of Natural Resources 被引量:1
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作者 Jiefang ZHU 《Meteorological and Environmental Research》 CAS 2020年第4期78-82,共5页
Marx's theory of scientific and technological progress and utilization of natural resources is an indispensable and important part of Marx's economic theory.To realize the harmonious unification of man and nat... Marx's theory of scientific and technological progress and utilization of natural resources is an indispensable and important part of Marx's economic theory.To realize the harmonious unification of man and nature,man must correctly understand the effect of scientific and technological progress on the use of natural resources,fundamentally solve the problem that scientific and technological progress cannot replace the position of natural resources in economic development,and objectively evaluate the relationship between human power and the power of nature.Grasping and comprehending the scientific connotation of Marx's theory of scientific and technological progress and utilization of natural resources has a very important theoretical value and practical significance for saving and effectively using natural resources and building an environment-friendly society. 展开更多
关键词 Scientific and technological progress Utilization of natural resources Values of the times
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Ten Times the Risk of Diabetes Genes Have Been Found
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《科技传播》 2014年第14期15-15,共1页
The gene mutation,found in the population of Greenland,will give clues to the different causes of the condition,say Danish scientists.The research,published in Nature,adds to evidence genetics plays a role in the chan... The gene mutation,found in the population of Greenland,will give clues to the different causes of the condition,say Danish scientists.The research,published in Nature,adds to evidence genetics plays a role in the chances of developing diabetes. 展开更多
关键词 GENETICS MUTATION times carrying nature LIFESTYLE
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The foundation of the theory of the universe dark energy and its nature
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作者 Murad Shibli 《Natural Science》 2011年第3期165-185,共21页
Surprisingly recent astronomical observations have provided strong evidence that our universe is not only expanding, but also is expanding at an accelerating rate. This paper pre- sents a basis of the theory of univer... Surprisingly recent astronomical observations have provided strong evidence that our universe is not only expanding, but also is expanding at an accelerating rate. This paper pre- sents a basis of the theory of universe space- time dark energy, a solution of Einstein’s cosmological constant problem, physical interpretation of universe dark energy and Einstein’s cosmological constant Lambda and its value ( = 0.29447 × 10-52 m-2), values of universe dark energy density 1.2622 × 10-26 kg/m3 = 6.8023 GeV, universe critical density 1.8069 × 10-26 kg/m3 = 9.7378 GeV, universe matter density 0.54207 × 10-26 kg/m3 = 2.9213 GeV, and universe radiation density 2.7103 × 10-31 kg/m3 = 1.455 MeV. The interpretation in this paper is based on geometric modeling of space-time as a perfect four- dimensional continuum cosmic fluid and the momentum generated by the time. In this modeling time is considered as a mechanical variable along with other variables and treated on an equal footing. In such a modeling, time is considered to have a mechanical nature so that the momentum associated with it is equal to the negative of the universe total energy. Since the momentum associated with the time as a mechanical variable is equal to the negative system total energy, the coupling in the time and its momentum leads to maximum increase in the space-time field with 70.7% of the total energy. Moreover, a null paraboloid is obtained and interpreted as a function of the momentum generated by time. This paper presents also an interpretation of space-time tri-dipoles, gravity field waves, and gravity carriers (the gravitons). This model suggests that the space-time has a polarity and is composed of dipoles which are responsible for forming the orbits and storing the space-time energy-momentum. The tri-di- poles can be unified into a solo space-time dipole with an angle of 45 degrees. Such a result shows that the space-time is not void, on the contrary, it is full of conserved and dynamic energy-momentum structure. Furthermore, the gravity field waves is modeled and assumed to be carried by the gravitons which move in the speed of light. The equivalent mass of the graviton (rest mass) is found to be equal to 0.707 of the equivalent mass of the light photons. Such a result indicates that the lightest particle (up to the author’s knowledge) in the nature is the graviton and has an equivalent mass equals to 2.5119 x 10-52 kg. Based on the fluidic nature of dark energy, a fourth law of thermodynamics is proposed and a new physical interpretation of Kepler’s Laws are presented. Additionally, based on the fact that what we are observing is just the history of our universe, on the Big Bang Theory, Einstein’s General Relativity, Hubble Parameter, cosmic inflation theory and on NASA’s observation of supernova 1a, then a second-order (parabolic) parametric model is obtained in this proposed paper to describe the accelerated ex- pansion of the universe. This model shows that the universe is approaching the universe cosmic horizon line and will pass through a critical point that will influence significantly its fate. Considering the breaking symmetry model and the variational principle of mechanics, then the universe will witness an infinitesimally stationary state and a symmetry breaking. As result of that, our universe will experience in the near future, a very massive impulse force in the order 1083 N. Subsequently, the universe will collapse. Finally, simulation results are demonstrated to verify the analytical results. 展开更多
关键词 DARK ENERGY nature of DARK ENERGY Expansion of the UNIVERSE Einstein’s Cosmological Constant UNIVERSE Mass/Energy Densities Space-Time DIPOLES GRAVITONS Fourth Law of thermodynamics Fate of the UNIVERSE Kelper’s Laws
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A NEW METHOD FOR FINDING THE NATURAL FREQUENCY SET OF A LINEAR TIME-INVARIANT NETWORK
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作者 吴雪 孙雨耕 《Transactions of Tianjin University》 EI CAS 1997年第2期28-35,共8页
提出了一种求线性定常n阶网络的固有频率集的新方法,给出了通用方程的推导及证明.该方法首次将n阶网络的固有频率与n端口网络参数相联系,方程形式简洁对偶,物理意义明确,求解简捷规范且不会产生丢根现象,具有通用性和系统性.
关键词 线性定常n阶网络 固有频率 n端口网络
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Is the September 5,2022,Luding MS6.8 earthquake an‘unexpected’event? 被引量:1
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作者 Shengfeng Zhang Zhongliang Wu Yongxian Zhang 《Earthquake Science》 2023年第1期76-80,共5页
After the September 5,2022(Beijing time).Luding Ms6.8 earthquake(29.59°N.102.08°E.depth 16 km.according to the initial determination by the China Earthquake Networks Center(CENC)).field investigation was car... After the September 5,2022(Beijing time).Luding Ms6.8 earthquake(29.59°N.102.08°E.depth 16 km.according to the initial determination by the China Earthquake Networks Center(CENC)).field investigation was carried out by the China Earthquake Administration(CEA).which associated the earthquake to the Moxi segment on the south part of the Xianshuihe fault system.This segment,with horizontal slip rate 5-10 mm/a.locates in the convergent part among the Xianshuihe fault. 展开更多
关键词 Luding MS6.8 earthquake ‘nowcasting earthquakes’ ‘natural time’ earthquake potential score(EPS)
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Identifying the occurrence time of an impending major earthquake:a review 被引量:1
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作者 Panayiotis A.Varotsos Nicholas V.Sarlis Efthimios S.Skordas 《Earthquake Science》 CSCD 2017年第4期209-218,共10页
The procedure through which the occurrence time of an impending major earthquake can be determined is reviewed in the light of the recent advances. This can be achieved by analyzing in natural time the seismicity in t... The procedure through which the occurrence time of an impending major earthquake can be determined is reviewed in the light of the recent advances. This can be achieved by analyzing in natural time the seismicity in the candidate area. To apply this general procedure, we need two important elements: first, to know when we should start the analysis, i.e., set the natural time equal to zero. This is the time at which the system enters the critical stage. Second a reliable estimation of the candidate epicentral area. If geoelectrical measurements are taken and the VAN method (after the initials of the three researchers Varotsos, Alexopoulos and Nomicos)is applied, both these elements become available upon the recording of a precursory Seismic Electric Signals (SES) activity, because its initiation marks the time when the system enters the critical stage, and in addition the SES data enable the determination of the epicentral area of the impending mainshock. On the other hand, if geoelectrical data are lacking, we make use of the following two recent findings by means of natural time analysis: First, the fluctuations of the order parameter of seismicity in a large area exhibit a minimum a few months before a major earthquake almost simultaneously with the initiation of an SES activity. Second, a spatiotemporal study of this minimum unveils an estimate of the epicentral area of the impending major earthquake. Two examples are given that refer to the strongest earthquakes that occurred in Greece and Japan during the last 3 decades, i.e., the Mw6.9 earthquake in southwestern Greece on 14 February 2008 and the Mw9.0 Tohoku earthquake in Japan on 11 March 2011. 展开更多
关键词 Seismic Electric Signals VAN method Natural time analysis Earthquake prediction
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A tentative model for the explanation of B?th law using the order parameter of seismicity in natural time 被引量:1
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作者 Konstantina A. Papadopoulou Efthimios S. Skordas Nicholas V. Sarlis 《Earthquake Science》 CSCD 2016年第6期311-319,共9页
Using the order parameter of seismicity defined in natural time, we suggest a simple model for the expla- nation of Bath law, according to which a mainshock differs in magnitude from its largest aftershock by approxim... Using the order parameter of seismicity defined in natural time, we suggest a simple model for the expla- nation of Bath law, according to which a mainshock differs in magnitude from its largest aftershock by approximately 1.2 regardless of the mainshock magnitude. In addition, the validity of Bath law is studied in the Global Centroid Moment Tensor catalogue by using two different aftershock definitions. It is found that the mean of this difference, when considering all the pairs mainshock-largest aftershock, does not markedly differ from 1.2 and the corresponding distributions do not depend on the mainshock's magnitude threshold in a statistically significant manner. Finally, the analysis of the cumulative distribution functions provides evidence in favour of the proposed model. 展开更多
关键词 Bath law . Aftershocks .Order parameter .Natural time
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Beyond Spacetime Geometry—The Death of Philosophy and Its Quantum Reincarnation 被引量:1
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作者 Wen-Ran Zhang 《Journal of Modern Physics》 2012年第9期1272-1284,共13页
Contrary to the “end” and “death” assertions on philosophy, this paper predicts an equilibrium-based and harmony-centered scientific reincarnation of philosophy. Logically, the reincarnation is backed by a formal ... Contrary to the “end” and “death” assertions on philosophy, this paper predicts an equilibrium-based and harmony-centered scientific reincarnation of philosophy. Logically, the reincarnation is backed by a formal system and a background independent geometry that transcends spacetime. Physically, it is supported by definable quantum causality and bipolar logical unifications of matter and antimatter, particle and wave, big bang and black hole, relativity and quantum entanglement. Philosophically, it is distinguished from Western metaphysics and dialectics as well as the Dao of Laozi. It is named a quantum reincarnation for its central claim that YinYang bipolar quantum entanglement is the source of causality for the Being of beings following the 2nd law of thermodynamics. Thus, it presents a modest unification of science and philosophy for their reciprocal interaction (Note: Equilibrium subsumes non-equilibrium and quasi—equilibrium as local non-equilibriums can form global equilibrium or quasi-equilibrium). 展开更多
关键词 End and Death of PHILOSOPHY BIPOLAR QUANTUM Entanglement YinYang BIPOLAR GEOMETRY Formal YinYang COSMOLOGY nature of Time QUANTUM Reincarnation of PHILOSOPHY
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On the Weissenberg effect of turbulence
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作者 Yu-Ning Huang Wei-Dong Su Cun-Biao Lee 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2019年第4期236-245,I0003,共11页
Within the framework of the Navier–Stokes equations,the Weissenberg effect of turbulence is investigated.We begin with our investigation on the elastic effect of homogeneous turbulent shear flow.First,in the sense of... Within the framework of the Navier–Stokes equations,the Weissenberg effect of turbulence is investigated.We begin with our investigation on the elastic effect of homogeneous turbulent shear flow.First,in the sense of Truesdell(Physics of Fluids,1964)on the natural time of materials,we derive the natural time of turbulence,and use it together with the natural viscosity of turbulence derived in the article of Huang et al.(Journal of Turbulence,2003)to define the natural Weissenberg number of turbulence as a measure of the elastic effect of homogeneous turbulence.Second,we define a primary Weissenberg number of turbulence,which in laminar flow reduces to the Weissenberg number widely applied in rheology to characterize the elasticity of visco-elastic fluids.Our analysis based on the experimental results of Tavoularis and Karnik(Journal of Fluid Mechanics,1989)indicates that the larger is the Weissenberg number of turbulence,the more elastic becomes the turbulent flow concerned.Furthermore,we put forth a general Weissenberg number of turbulence,which includes the primary Weissenberg number of turbulence as a special case,to measure the overall elastic effects of turbulence.Besides,it is shown that the general Weissenberg number can also be used to characterize the elastic effects of non-Newtonian fluids in laminar flow. 展开更多
关键词 NORMAL stress DIFFERENCE Natural time of TURBULENCE Weissenberg NUMBER of TURBULENCE ELASTIC EFFECT Non-Newtonian fluid
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The impacts of market reform on the market penetration of natural gas-fired electricity and renewable energy in China 被引量:4
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作者 Li-Jing Zhu Yan Li +2 位作者 Yan-Yan Tang Yao-Ming Li Qi Zhang 《Petroleum Science》 SCIE CAS CSCD 2017年第4期831-841,共11页
Natural gas-fired electricity(NGFE) is expected to play a more important role in the future due to its characteristics of low pollution, high efficiency and flexibility. However, its development in China is impeded by... Natural gas-fired electricity(NGFE) is expected to play a more important role in the future due to its characteristics of low pollution, high efficiency and flexibility. However, its development in China is impeded by its high regulation price compared with coal power. Market reform is therefore of vital importance to promote the penetration of NGFE. The objective of this study is to analyze the impacts of market reform and the renewable electricity(RE) subsidy policy on the promotion of NGFE and RE. A dynamic game-theoretic model is developed to analyze the interaction among the NG supplier, the power sector and the power grid. Three scenarios are proposed with different policies, including a fixed regulation price of NG and electricity, real-time pricing(RTP) of NG and electricity, and subsidy targeted at RE. The results show that:(1) market reform can sharply decrease the NG price and consequently promote the development of NGFE and RE;(2) subsidy targeted at RE not only promotes the penetration of NGFE and RE, but also increases the utilization ratio of renewables significantly;(3) market reform and the subsidy also enhance consumers’ welfare by reducing their power consumption expenditure. 展开更多
关键词 Natural gas-fired electricity Renewable electricity Real-time pricing Market reform Game-theoretic model
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Identifying the occurrence time of an impending mainshock:a very recent case
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作者 Panayiotis A.Varotsos Nicholas V.Sarlis +2 位作者 Efthimios S.Skordas Stavros-Richard G.Christopoulos Mary S.Lazaridou-Varotsos 《Earthquake Science》 CSCD 2015年第3期215-222,共8页
The procedure by means of which the occurrence time of an impending mainshock can be identified by analyzing in natural time the seismicity in the candidate area subsequent to the recording of a precursory seismic ele... The procedure by means of which the occurrence time of an impending mainshock can be identified by analyzing in natural time the seismicity in the candidate area subsequent to the recording of a precursory seismic electric signals(SES) activity is reviewed. Here, we report the application of this procedure to an MW5.4 mainshock that occurred in Greece on 17 November 2014. This mainshock(which is pretty rare since it is the strongest in that area for more than half a century) was preceded by an SES activity recorded on 27 July 2014, and the results of the natural time analysis reveal that the system approached the critical point(mainshock occurrence) early in the morning on 15 November 2014. 展开更多
关键词 Seismic electric signals Natural time analysis Earthquake prediction Critical phenomena
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Study and Simulated the Natural Radioactivity (NORM) U-238, Th-232 and K-40 of Igneous and Sedimentary Rocks of Al-Atawilah (Al-Baha) in Saudi Arabia
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作者 Bashayer M. Al-Zahrani Haifa S. Alqannas Safia H. Hamidalddin 《World Journal of Nuclear Science and Technology》 2020年第4期171-181,共11页
In this work, gamma-ray spectroscopy based on semiconductor hyper pure germanium (HPGe) detector was used to evaluate the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the ... In this work, gamma-ray spectroscopy based on semiconductor hyper pure germanium (HPGe) detector was used to evaluate the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) for thirty samples of igneous and sedimentary rocks of Al-Atawilah (Al-Baha). The mean values of the activity concentrations of U-238 (Ra-226), Th-232, K-40 and Cs-137 in the igneous samples are found as (11.0, 11.50, 1172.71, 1.47) Bq/Kg respectively. In the sedimentary rocks, the mean values of the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) equal to (12.04, 13.18, 1131.36, 1.60) Bq/Kg respectively. The averages of radiological hazards (<em>Ra</em><sub><em>eq</em></sub>, <em>H</em><sub><em>ex</em></sub> and <em>I</em><sub><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&gamma;</span></span></em></sub>) were calculated and found to be within the UNSCEAR permissible limit values (370 Bq/kg for <em>Ra</em><sub><em>eq</em></sub>, and 1 for <em>H</em><sub><em>ex</em></sub> and <em>I</em><sub><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&gamma;</span></span></em></sub>), except for a slight increase of average value of <em>I</em><sub><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&gamma;</span></span></em></sub> in the igneous rock samples (1.36). The results indicate that the dose rate values depend on the kind of rocks (high in some igneous rock samples, and most of sedimentary rock samples have low dose rate). The activities of naturalnuclides were predicted and simulated in T time using a written MATLAB R2020a script based on the average activity concentrations and respective half-lives of U-238 and Th-232 series, and K-40, this is to evaluate the future effects of natural radionuclides on the population and estimate the human inputs in the future. 展开更多
关键词 Natural Radioactivity Gamma-Ray Spectroscopy Activity Concentration Igneous and Sedimentary Rocks Simulated in T Time
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Discussion on the Theory of Pricking Blood in Nei Jing from the Perspective of Time
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作者 Jing-Jie Yang Hai-Yan Ren 《History & Philosophy of Medicine》 2020年第2期47-53,共7页
Objective:The purpose of this paper is to explore the influence of time factors recorded in Nei Jing,such as changes of Yin Yang in four seasons,the wax and wane of the moon and the rhythm of Yin Yang in a day,on pric... Objective:The purpose of this paper is to explore the influence of time factors recorded in Nei Jing,such as changes of Yin Yang in four seasons,the wax and wane of the moon and the rhythm of Yin Yang in a day,on pricking blood therapy.Methods:The contents of pricking blood according to time in Nei Jing is studied by using the method of literature review.Results:Through the research,this paper concludes that(1)pricking blood according to time takes"the correspondence between nature and man"as the dominant thought,"meridian Qi and Blood"as the regulating object,and"time factor"as the specie operation key,which reflects the influence of time on pricking blood therapy;(2)pricking blood therapy has different speci行c operations according to different time,which can be roughly divided into three situations.One is to prick blood according to the change of seasons,pricking shallowly with expelling less blood in spring and summer and pricking deeply with squeezing more blood out in autumn and winter.The second is pricking blood according to the laws of moon's wax and wane.When the moon is born,the amount of bleeding should be less;when the moon is full,the amount of bleeding should be more;when the moon wanes,pricking blood therapy should not be used.Thirdly,take pricking blood therapy according to circadian rhythm.It is more suitable to use pricking blood therapy in the morning than afternoon.Conclusion:As a characteristic therapy of TCM,pricking blood embodies the idea of"the correspondence between nature and man"in TCM.Adopting different pricking blood rules according to the change of time can improve the clinical therapeutic effect.The thought of pricking according to time plays an important guiding role in the application of pricking blood therapy in clinic. 展开更多
关键词 Nei Jing CIRCADIAN RHYTHM Pricking BLOOD Pricking BLOOD according to TIME CORRESPONDENCE between nature and man MERIDIAN Qi and BLOOD
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Theory and Application of Natural-Based Wavelet Method
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作者 Yanhua Cao Mengcheng Chen Baogen Xu 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2019年第6期86-90,共5页
Wavelet method is often used in analyzing trend and period of time sequence. When using wavelet method one serious problem is different chosen wavelet basis and scale would lead to different results. Sometimes, the re... Wavelet method is often used in analyzing trend and period of time sequence. When using wavelet method one serious problem is different chosen wavelet basis and scale would lead to different results. Sometimes, the results vary greatly. To overcome this problem and to improve the accuracy and efficiency, a new method denoted by Natural-based Wavelet Method is introduced and extended. It can be proved that the proposed method in fact is a special class of discrete wavelet. At first, two numerical examples are designed to show the capacity of the novel method. Second, this method is applied to a precipitation series. According to wavelet analysis and short-range precipitation prediction, this precipitation exists a faintly increasing trend. Through the analysis, the studied precipitation has two major periods: 11 and 41 years. The results validate that the Natural-based Wavelet Method used in application of multi-complicated observed data is suitable. It is easy to write the source code of the proposed method. When new information appears, new information can be easily added into the original sequence, this is another advantage of the proposed method. 展开更多
关键词 natural-based wavelet method long-time precipitation sequence short-range precipitation time sequence
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The Quantitative Identification of Regional Mine and Natural Earthquakes and Its Application
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作者 Liu Xiqiang Du Yihe +3 位作者 Xu Bo Li Hong Shen Ping Zhang Ping 《Earthquake Research in China》 2005年第3期269-281,共13页
Earthquake Administration of Liaoning Province, Shenyang 100031, China Based on the Morlet wavelet transform and digital data from the Fushun and Beizhen seismic stations, Liaoning Province, we put forward a new metho... Earthquake Administration of Liaoning Province, Shenyang 100031, China Based on the Morlet wavelet transform and digital data from the Fushun and Beizhen seismic stations, Liaoning Province, we put forward a new method in the paper, called time-frequency energy attenuation factor (α-value). The characteristics of the α-value and its variation with magnitude of natural and mine earthquakes are studied, and the statistic relations between the α-value and specific earthquake magnitude are obtained. From the results, some conclusions can be drawn as follows: (1) in general, the α-values of mine and natural earthquakes of the same intensity have obvious difference and the ranges of their variation do not overlap each other; (2) the α-value decreases with the increase of earthquake magnitude, and the α-value of mine earthquake decreases faster than that of natural earthquake; (3) based on the earthquake magnitude and on the relations between the α-value and earthquake magnitude, we can distinguish the mine earthquakes from the natural ones; (4) the difference in focal mechanism of mine and natural earthquakes would be the main cause for obvious difference of the α-value; (5) the α-value variation is relatively steady for mine and natural earthquakes that occur in the same region, but it has obvious regional difference. The above results are of inspirational meaning for the study of abnormal change of the α-value before strong earthquakes. 展开更多
关键词 地震 煤矿 地球构造 地质条件 自然应力
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Variation of the Energy Field of Longmenshan Fault Zone before the Wenchuan M_S 8. 0 Earthquake
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作者 Yang Mingzhi Ma Heqing 《Earthquake Research in China》 2012年第3期355-364,共10页
During the process of preparation and occurrence of a large earthquake,the stress-strain state along the fault zone has close relation with the weak seismicity around the fault zone. The seismic energy release near th... During the process of preparation and occurrence of a large earthquake,the stress-strain state along the fault zone has close relation with the weak seismicity around the fault zone. The seismic energy release near the fault zone before an earthquake can better reflect the dynamic process of earthquake preparation. Thus,in this paper,the method of natural orthogonal function expansion has been adopted to discuss the time variation about the energy field of the seismic activity along the Longmenshan fault zone before the Wenchuan M_S 8. 0 earthquake,2008. The results show that evident short-term rise changes appeared in the time factors of the typical field corresponding to several key eigenvalues of the energy field along the Longmenshan fault zone before the Wenchuan earthquake,probably being the short-term anomaly message for this earthquake. Through contrastive analysis of earthquake examples such as the 1976 Tangshan earthquake,the authors think that the study of time variation of energy field of seismicity along active fault zone will be helpful for conducting intentional and intensive earthquake monitoring and forecast in active fault regions with high seismic risk based on medium- and long-term earthquake trend judgment. 展开更多
关键词 龙门山断裂带 能源领域 地震前 汶川 地震短期异常 地震活动性 唐山大地震 活动断裂带
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Helmholtz Theorems, Gauge Transformations, General Covariance and the Empirical Meaning of Gauge Conditions
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作者 Andrew Chubykalo Augusto Espinoza Rolando Alvarado Flores 《Journal of Modern Physics》 2016年第9期1021-1044,共24页
It is well known that the use of Helmholtz decomposition theorem for static vector fields , when applied to the time dependent vector fields , which represent the electromagnetic field, allows us to obtain instan... It is well known that the use of Helmholtz decomposition theorem for static vector fields , when applied to the time dependent vector fields , which represent the electromagnetic field, allows us to obtain instantaneous-like solutions all along . For this reason, some people thought (see e.g. [1] and references therein) that the Helmholtz theorem cannot be applied to time dependent vector fields and some modification is wanted in order to get the retarded solutions. However, the use of the Helmholtz theorem for static vector fields is correct even for time dependent vector fields (see, e.g. [2]), so a relation between the solutions was required, in such a way that a retarded solution can be transformed in an instantaneous one, and conversely. On this paper we want to suggest, following most of the time the mathematical formalism of Woodside in [3], that: 1) there are many Helmholtz decompositions, all equally consistent, 2) each one is naturally related to a space-time structure, 3) when we use the Helmholtz decomposition for the electromagnetic potentials it is equivalent to a gauge transformation, 4) there is a natural methodological criterion for choosing the gauge according to the structure postulated for a global space-time, 5) the Helmholtz decomposition is the manifestation at the level of the fields that a gauge is involved. So, when we relate the retarded solution to the instantaneous one what we do is to change the gauge and the space-time. And, if the Helmholtz decompositions are related to a space-time structure, and are equivalent to gauge transformations, each gauge transformation is natural for a specific space-time. In this way, a Helmholtz decomposition for Euclidean space is equivalent to the Coulomb gauge and a Helmholtz decomposition for the Minkowski space is equivalent to the Lorenz gauge. This leads us to consider that the theories defined by different gauges may be mathematically equivalent, because they can be related by means of a gauge transformation, but they are not empirically equivalent, because they have quite different observational consequences due to the different space-time structure involved. 展开更多
关键词 Helmholtz theorem Gauge Transformations Space-Time Transformations Symmetries of Differential Equations Underdetermination of Systems of Differential Equations Natural Covariance
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天然气管道可靠性增长预测方法研究
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作者 张鹏 宋文琦 +2 位作者 肖博文 刘为 赵明 《中国安全生产科学技术》 CAS CSCD 北大核心 2024年第1期114-120,共7页
为减少天然气管道投产前的设计和制造缺陷,提高使用寿命、运行可靠性和安全性、减少后期维修费用,通过统计模型结合试验数据实现对天然气管道可靠性增长水平的预测,提出天然气管道可靠性增长预测方法;分析常用可靠性增长模型并结合天然... 为减少天然气管道投产前的设计和制造缺陷,提高使用寿命、运行可靠性和安全性、减少后期维修费用,通过统计模型结合试验数据实现对天然气管道可靠性增长水平的预测,提出天然气管道可靠性增长预测方法;分析常用可靠性增长模型并结合天然气管道可维修、小子样的特点,将Duane模型与AMSAA模型应用于天然气管道,结合点估计、趋势检验、拟合优度检验、区间估计和标准差,得出天然气管道可靠性增长模型,预测可靠性增长并进行实例验证。研究结果表明:Duane模型与AMSAA模型作为天然气管道可靠性增长试验具有可行性;其中AMSAA模型更具优势,得出天然气管道的瞬时无故障工作时间(MTBF)估计值可达到试验目标值,并预测MTBF达到2000 h时所需要的试验时间为317954611.3 h,未来第51次故障预测区间为[848.4609,939.6226],误差为1.25%,方法具有良好的适用性,可有效预测天然气管道可靠性增长。研究结果可为天然气管道设计改进提供指导。 展开更多
关键词 天然气管道 可靠性增长 DUANE模型 AMSAA模型 MTBF
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税收征管规范化与企业盈余管理--基于税务行政处罚裁量基准的准自然实验
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作者 刘秋平 吴愉正 《盐城工学院学报(社会科学版)》 2024年第2期46-52,共7页
以2013—2022十年里我国A股上市公司数据为样本探究税收征管规范化与企业盈余管理之间的关系。研究结果表明,各地税务行政处罚裁量基准的实施显著降低了企业的盈余管理水平,并且进一步发现该现象在非国有产权性质和内部控制薄弱的企业... 以2013—2022十年里我国A股上市公司数据为样本探究税收征管规范化与企业盈余管理之间的关系。研究结果表明,各地税务行政处罚裁量基准的实施显著降低了企业的盈余管理水平,并且进一步发现该现象在非国有产权性质和内部控制薄弱的企业中更为明显。 展开更多
关键词 税收征管 盈余管理 税务行政处罚裁量基准 准自然实验 多时点双重差分法
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