Today developed countries mainly participate in international trade via their foreign affiliates and intermediate goods are more frequently traded as a result of increasingly deepening international divisions of labou...Today developed countries mainly participate in international trade via their foreign affiliates and intermediate goods are more frequently traded as a result of increasingly deepening international divisions of labour.Against this background,the current trade statistical system that is characterized by the statistical principle of cross-border trade and production,and the custom’s registration data collection method,greatly exaggerate the trade imbalance between China and America. Consequently,it is necessary for the Chinese nation to overcome the shortcomings of the current statistical system so as to evaluate more fairly the trade imbalance between China and America by referring to the Ownership-Based Framework of the complimentary statistical system under the US Current Account.This article, on the basis of the statistical principle of oumership,attempts to regulate the distorted trade imbalance resulting from the current trade statistical system,and aims for an increased understanding of the trade imbalance between China and America from a theoretical background,as well as from the points of view of practitioners and decision makers.展开更多
Safety-critical system （SCS） has highly demand for dependability, which requires plenty of resource to ensure that the system under test （SUT） satisfies the dependability requirement. In this paper, a new SCS rapi...Safety-critical system （SCS） has highly demand for dependability, which requires plenty of resource to ensure that the system under test （SUT） satisfies the dependability requirement. In this paper, a new SCS rapid testing method is proposed to improve SCS adaptive dependability testing. The result of each test execution is saved in calculation memory unit and evaluated as an algorithm model. Then the least quantity of scenario test case for next test execution will be calculated according to the promised SUT＇s confidence level. The feedback data are generated to weight controller as the guideline for the further testing. Finally, a compre- hensive experiment study demonstrates that this adaptive testing method can really work in practice. This rapid testing method, testing result statistics-based adaptive control, makes the SCS dependability testing much more effective.展开更多
We theoretically study the statistics of photon emission of single multi-level quantum system by employing the generating functions approach developed recently. The generalized decay constants are included in single m...We theoretically study the statistics of photon emission of single multi-level quantum system by employing the generating functions approach developed recently. The generalized decay constants are included in single multi-level quantum system with quasi-degenerated levels in this work although they are normally neglected in the absence of （quasi-）degeneracies in multi-level quantum system within the rotating wave approximation. The quantum beats, the line shapes and the Mandel＇s Q parameters, etc. are studied.展开更多
We investigate the influence of the field fluctuations to the emission photons of V-type three-level systems.The emission intensity I and Mandel＇s Q parameter show stochastic resonance with respect to the pure dephas...We investigate the influence of the field fluctuations to the emission photons of V-type three-level systems.The emission intensity I and Mandel＇s Q parameter show stochastic resonance with respect to the pure dephasing constantγp.The amplitude fluctuation of the field causes these systems to lose their coherence.On the other hand,the amplitude fluctuation provides a new interference method for these systems.The quantum beats are shown in the orthogonal system.展开更多
During the evolution of the global economic, high and new technology industry has become the main driver to impel the global economy growth via technological advancement, and the main means to guarantee the sustainabl...During the evolution of the global economic, high and new technology industry has become the main driver to impel the global economy growth via technological advancement, and the main means to guarantee the sustainable development of the global economy. In the view of China’s situation, this article analyzes the experiences of OECD in high and new technology industry and gives a statistics index system along with the evaluation method to estimate the development of high and new technology industry.展开更多
Recent experiments have demonstrated the realization of the three-dimensional quantum Hall effect in highly anisotropic crystalline materials, such as ZrTe|_5 and BaMnSb_2. Such a system supports chiral surface states...Recent experiments have demonstrated the realization of the three-dimensional quantum Hall effect in highly anisotropic crystalline materials, such as ZrTe|_5 and BaMnSb_2. Such a system supports chiral surface states in the presence of a strong magnetic field, which exhibit a one-dimensional metal-insulator crossover due to suppression of surface diffusion by disorder potential. We study the nontrivial surface states in a lattice model and find a wide crossover of the level-spacing distribution through a semi-Poisson distribution. We also discover a nonmonotonic evolution of the level statistics due to the disorder-induced mixture of surface and bulk states.展开更多
In the new era,the impact of emerging productive forces has permeated every sector of industry.As the core production factor of these forces,data plays a pivotal role in industrial transformation and social developmen...In the new era,the impact of emerging productive forces has permeated every sector of industry.As the core production factor of these forces,data plays a pivotal role in industrial transformation and social development.Consequently,many domestic universities have introduced majors or courses related to big data.Among these,the Big Data Management and Applications major stands out for its interdisciplinary approach and emphasis on practical skills.However,as an emerging field,it has not yet accumulated a robust foundation in teaching theory and practice.Current instructional practices face issues such as unclear training objectives,inconsistent teaching methods and course content,insufficient integration of practical components,and a shortage of qualified faculty-factors that hinder both the development of the major and the overall quality of education.Taking the statistics course within the Big Data Management and Applications major as an example,this paper examines the challenges faced by statistics education in the context of emerging productive forces and proposes corresponding improvement measures.By introducing innovative teaching concepts and strategies,the teaching system for professional courses is optimized,and authentic classroom scenarios are recreated through illustrative examples.Questionnaire surveys and statistical analyses of data collected before and after the teaching reforms indicate that the curriculum changes effectively enhance instructional outcomes,promote the development of the major,and improve the quality of talent cultivation.展开更多
With the implementation of General Senior High School Mathematics Curriculum Standards(2017 Edition,Revised in 2020),probability and statistics,as important carriers of the core mathematical competencies“mathematical...With the implementation of General Senior High School Mathematics Curriculum Standards(2017 Edition,Revised in 2020),probability and statistics,as important carriers of the core mathematical competencies“mathematical modeling”and“data analysis,”have increasingly highlighted their educational value.By summarizing the historical evolution of probability and statistics thinking and combining with teaching practice cases,this study explores its unique role in cultivating students’core mathematical competencies.The research proposes a project-based teaching strategy relying on real scenarios and empowered by technology.Through cases,it demonstrates how to use modern educational technology to realize the whole-process exploration of data collection,model construction,and conclusion verification,so as to promote the transformation of middle school probability and statistics teaching from knowledge imparting to competency development,and provide a practical reference for curriculum reform.展开更多
This paper focuses on the ideological and political construction of the course“Probability Theory and Mathematical Statistics.”Aiming at the current situation in teaching where emphasis is placed on knowledge impart...This paper focuses on the ideological and political construction of the course“Probability Theory and Mathematical Statistics.”Aiming at the current situation in teaching where emphasis is placed on knowledge imparting while value guidance is neglected,and combined with the requirements of ideological and political education policies in the new era,this paper explores the integration path between professional courses and ideological and political education.Through literature analysis,case comparison,and empirical research,the study proposes a systematic implementation plan covering the design of teaching objectives,the reconstruction of teaching content,and the optimization of the evaluation system.The purpose is to cultivate students’sense of social responsibility and innovative awareness by excavating the ideological and political elements in mathematics.The research results provide practical reference for colleges and universities to deepen the reform of ideological and political education in courses,and promote the implementation of the fundamental task of fostering virtue through education in STEM education.展开更多
Reconfigurable intelligent surface(RIS)is a promising candidate technology of the upcoming Sixth Generation(6G)communication system for its ability to provide unprecedented spectral and energy efficiency increment thr...Reconfigurable intelligent surface(RIS)is a promising candidate technology of the upcoming Sixth Generation(6G)communication system for its ability to provide unprecedented spectral and energy efficiency increment through passive beamforming.However,it is challenging to obtain instantaneous channel state information(I-CSI)for RIS,which obliges us to use statistical channel state information(S-CSI)to achieve passive beamforming.In this paper,RIS-aided multiple-input single-output(MISO)multi-user downlink communication system with correlated channels is investigated.Then,we formulate the problem of joint beamforming design at the AP and RIS to maximize the sum ergodic spectral efficiency(ESE)of all users to improve the network capacity.Since it is too hard to compute sum ESE,an ESE approximation is adopted to reformulate the problem into a more tractable form.Then,we present two joint beamforming algorithms,namely the singular value decomposition-gradient descent(SVD-GD)algorithm and the fractional programming-gradient descent(FP-GD)algorithm.Simulation results show the effectiveness of our proposed algorithms and validate that 2-bits quantizer is enough for RIS phase shifts implementation.展开更多
The ability to accurately simulate the time evolu-tion of quantum systems stands as a cornerstone of modern molecular science.It provides the essential mechanistic bridge between a system’s microscopic structure and ...The ability to accurately simulate the time evolu-tion of quantum systems stands as a cornerstone of modern molecular science.It provides the essential mechanistic bridge between a system’s microscopic structure and its macroscopic function,a challenge first envisioned by Feynman.The central difficulty,and the unifying theme of this Special Topic,is the problem of“complexity”:a multifaceted challenge arising from the interplay of strongly coupled electronic and vibrational degrees of freedom,quantum statistics,and the non-trivial,often non-Markovian,memory effects exerted by a surrounding environment.展开更多
Variation of reservoir physical properties can cause changes in its elastic parameters. However, this is not a simple linear relation. Furthermore, the lack of observations, data overlap, noise interference, and ideal...Variation of reservoir physical properties can cause changes in its elastic parameters. However, this is not a simple linear relation. Furthermore, the lack of observations, data overlap, noise interference, and idealized models increases the uncertainties of the inversion result. Thus, we propose an inversion method that is different from traditional statistical rock physics modeling. First, we use deterministic and stochastic rock physics models considering the uncertainties of elastic parameters obtained by prestack seismic inversion and introduce weighting coefficients to establish a weighted statistical relation between reservoir and elastic parameters. Second, based on the weighted statistical relation, we use Markov chain Monte Carlo simulations to generate the random joint distribution space of reservoir and elastic parameters that serves as a sample solution space of an objective function. Finally, we propose a fast solution criterion to maximize the posterior probability density and obtain reservoir parameters. The method has high efficiency and application potential.展开更多
Ocean waves are the core environmental elements affecting the movements and structure design of ships. Statistical analysis of wave parameters is the basis for the establishment of long-term ship environmental adaptab...Ocean waves are the core environmental elements affecting the movements and structure design of ships. Statistical analysis of wave parameters is the basis for the establishment of long-term ship environmental adaptability prediction model. The observations from coastal stations, buoys, altimeters and volunteer ships that cover from 1993 to 2011 were interpolated into miller Ion-lat grids by using bilinear method and the analytical fields of ocean waves were given. By using optimal interpolation, the analysis wave fields were assimilated into the WAVEWATCH III （WW3） simulation results. From the assimilated results, the wave rose statistics, the wave height of muitiyear return period and the extreme 2-D wave spectrum are related to the ship seakeeping were calculated. Finally, the wave statistics in China offshore were analyzed in detail.展开更多
To take into account the influence of uncetainties on the dynamic response of the vibro-acousitc structure, a hybrid modeling technique combining the finite element method（FE）and the statistic energy analysis（SEA）...To take into account the influence of uncetainties on the dynamic response of the vibro-acousitc structure, a hybrid modeling technique combining the finite element method（FE）and the statistic energy analysis（SEA） is proposed to analyze vibro-acoustics responses with uncertainties at middle frequencies. The mid-frequency dynamic response of the framework-plate structure with uncertainties is studied based on the hybrid FE-SEA method and the Monte Carlo（MC）simulation is performed so as to provide a benchmark comparison with the hybrid method. The energy response of the framework-plate structure matches well with the MC simulation results, which validates the effectiveness of the hybrid FE-SEA method considering both the complexity of the vibro-acoustic structure and the uncertainties in mid-frequency vibro-acousitc analysis. Based on the hybrid method, a vibroacoustic model of a construction machinery cab with random properties is established, and the excitations of the model are measured by experiments. The responses of the sound pressure level of the cab and the vibration power spectrum density of the front windscreen are calculated and compared with those of the experiment. At middle frequencies, the results have a good consistency with the tests and the prediction error is less than 3. 5dB.展开更多
In order to reduce the enormous pressure to environmental monitoring work brought by the false sewage monitoring data, Grubbs method, box plot, t test and other methods are used to make depth analysis to the data, pro...In order to reduce the enormous pressure to environmental monitoring work brought by the false sewage monitoring data, Grubbs method, box plot, t test and other methods are used to make depth analysis to the data, providing a set of technological process to identify the sewage monitoring data, which is convenient and simple.展开更多
With the illustration of a specific problem, this paper demonstrates that using Monte Carlo Simulation technology will improve intuitive effect of teaching Probability and Mathematical Statistics course, and save inst...With the illustration of a specific problem, this paper demonstrates that using Monte Carlo Simulation technology will improve intuitive effect of teaching Probability and Mathematical Statistics course, and save instructors' effort as well.And it is estimated that Monte Carlo Simulation technology will be one of the major teaching methods for Probability and Mathematical Statistics course in the future.展开更多
“Four classes of enterprises above designated size”(hereinafter called four-classes enterprises)refer to objects of statistical survey that have reached a certain scale in China’s current statistical method system,...“Four classes of enterprises above designated size”(hereinafter called four-classes enterprises)refer to objects of statistical survey that have reached a certain scale in China’s current statistical method system,including four classes in national economy,namely,industrial enterprises above designated size,construction and real estate development and management enterprises above qualifications,wholesale and retail,catering and accommodation enterprises,and service enterprises above designated size,which are the primary part of national economic and social development activities.This paper is focused on analyzing the practice and difficulties in the current statistics work of four-classes enterprises,and then this paper proposes some recommendations.展开更多
AIM To provide a quantitative assessment of theassociation between type 2 diabetes mellitus （T2DM）and the risk of colorectal cancer （CRC）.METHODS： Systematic review was conductedthorough MEDLINE, EMBASE, Cochrane...AIM To provide a quantitative assessment of theassociation between type 2 diabetes mellitus （T2DM）and the risk of colorectal cancer （CRC）.METHODS： Systematic review was conductedthorough MEDLINE, EMBASE, Cochrane Library, and ISI Web of knowledge databases till 31st January 2014.This meta-analysis included the cohort studies thatillustrated relative risk （RR） or odds ratio estimateswith 95%CI for the predictive risk of CRC by T2DM.Summary relative risks with 95%CI were analyzed byusing an effects summary ratio model. Heterogeneityamong studies was assessed by the Cochran＇s Q and I 2statistics.RESULTS： The meta analysis of 8 finally selectedstudies showed a positive correlation of T2DM withthe risk of CRC as depicted by effects summary RRof 1.21 （95%CI： 1.02-1.42）. Diabetic women showedgreater risk of developing CRC as their effect summaryRR of 1.22 （95%CI： 1.01-49） with significant overallZ test at 5% level of significance was higher than theeffect summary RR of 1.17 （95%CI： 1.00-1.37） of menshowing insignificant Z test. The effect summary RRof 1.19 with 95%CI of 1.07-1.33 indicate a positiverelationship between DM and increased risk of CRCwith significant heterogeneity （I 2 = 92% and P -value 〈0.05）.CONCLUSION： Results from this systematic reviewand meta-analysis report that diabetic people have anincreased risk of CRC as compared to non-diabetics.展开更多
基金Project supported by Provincial Natural Science Foundation of Anhui Universities(Approval number:KJ2007B258)
文摘Today developed countries mainly participate in international trade via their foreign affiliates and intermediate goods are more frequently traded as a result of increasingly deepening international divisions of labour.Against this background,the current trade statistical system that is characterized by the statistical principle of cross-border trade and production,and the custom’s registration data collection method,greatly exaggerate the trade imbalance between China and America. Consequently,it is necessary for the Chinese nation to overcome the shortcomings of the current statistical system so as to evaluate more fairly the trade imbalance between China and America by referring to the Ownership-Based Framework of the complimentary statistical system under the US Current Account.This article, on the basis of the statistical principle of oumership,attempts to regulate the distorted trade imbalance resulting from the current trade statistical system,and aims for an increased understanding of the trade imbalance between China and America from a theoretical background,as well as from the points of view of practitioners and decision makers.
基金the National 863 Program under Grant No. 2006AA01Z173.
文摘Safety-critical system （SCS） has highly demand for dependability, which requires plenty of resource to ensure that the system under test （SUT） satisfies the dependability requirement. In this paper, a new SCS rapid testing method is proposed to improve SCS adaptive dependability testing. The result of each test execution is saved in calculation memory unit and evaluated as an algorithm model. Then the least quantity of scenario test case for next test execution will be calculated according to the promised SUT＇s confidence level. The feedback data are generated to weight controller as the guideline for the further testing. Finally, a compre- hensive experiment study demonstrates that this adaptive testing method can really work in practice. This rapid testing method, testing result statistics-based adaptive control, makes the SCS dependability testing much more effective.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10674083 and 10874102)partially by the Research Fund for the Doctoral Program of Higher Education(Grant No.200804220004)the support from the National Found for Fostering Talents of Basic Science(NFFTBS)(Grant No.J0730318)
文摘We theoretically study the statistics of photon emission of single multi-level quantum system by employing the generating functions approach developed recently. The generalized decay constants are included in single multi-level quantum system with quasi-degenerated levels in this work although they are normally neglected in the absence of （quasi-）degeneracies in multi-level quantum system within the rotating wave approximation. The quantum beats, the line shapes and the Mandel＇s Q parameters, etc. are studied.
基金supported by the National Natural Science Foundation of China(Grand Nos.91021009,21073110,and 11374191)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2013AQ020)+1 种基金the Postdoctoral Science Foundation of China(Grant No.2013M531584)the Doctoral Program of Higher Education of China(Grant Nos.20130131110005 and 20130131120006)
文摘We investigate the influence of the field fluctuations to the emission photons of V-type three-level systems.The emission intensity I and Mandel＇s Q parameter show stochastic resonance with respect to the pure dephasing constantγp.The amplitude fluctuation of the field causes these systems to lose their coherence.On the other hand,the amplitude fluctuation provides a new interference method for these systems.The quantum beats are shown in the orthogonal system.
文摘During the evolution of the global economic, high and new technology industry has become the main driver to impel the global economy growth via technological advancement, and the main means to guarantee the sustainable development of the global economy. In the view of China’s situation, this article analyzes the experiences of OECD in high and new technology industry and gives a statistics index system along with the evaluation method to estimate the development of high and new technology industry.
基金Supported by the National Natural Science Foundation of China (Grant No.11674282)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDB28000000)。
文摘Recent experiments have demonstrated the realization of the three-dimensional quantum Hall effect in highly anisotropic crystalline materials, such as ZrTe|_5 and BaMnSb_2. Such a system supports chiral surface states in the presence of a strong magnetic field, which exhibit a one-dimensional metal-insulator crossover due to suppression of surface diffusion by disorder potential. We study the nontrivial surface states in a lattice model and find a wide crossover of the level-spacing distribution through a semi-Poisson distribution. We also discover a nonmonotonic evolution of the level statistics due to the disorder-induced mixture of surface and bulk states.
文摘In the new era,the impact of emerging productive forces has permeated every sector of industry.As the core production factor of these forces,data plays a pivotal role in industrial transformation and social development.Consequently,many domestic universities have introduced majors or courses related to big data.Among these,the Big Data Management and Applications major stands out for its interdisciplinary approach and emphasis on practical skills.However,as an emerging field,it has not yet accumulated a robust foundation in teaching theory and practice.Current instructional practices face issues such as unclear training objectives,inconsistent teaching methods and course content,insufficient integration of practical components,and a shortage of qualified faculty-factors that hinder both the development of the major and the overall quality of education.Taking the statistics course within the Big Data Management and Applications major as an example,this paper examines the challenges faced by statistics education in the context of emerging productive forces and proposes corresponding improvement measures.By introducing innovative teaching concepts and strategies,the teaching system for professional courses is optimized,and authentic classroom scenarios are recreated through illustrative examples.Questionnaire surveys and statistical analyses of data collected before and after the teaching reforms indicate that the curriculum changes effectively enhance instructional outcomes,promote the development of the major,and improve the quality of talent cultivation.
基金2021 Annual Research Project of Yili Normal University(2021YSBS012)。
文摘With the implementation of General Senior High School Mathematics Curriculum Standards(2017 Edition,Revised in 2020),probability and statistics,as important carriers of the core mathematical competencies“mathematical modeling”and“data analysis,”have increasingly highlighted their educational value.By summarizing the historical evolution of probability and statistics thinking and combining with teaching practice cases,this study explores its unique role in cultivating students’core mathematical competencies.The research proposes a project-based teaching strategy relying on real scenarios and empowered by technology.Through cases,it demonstrates how to use modern educational technology to realize the whole-process exploration of data collection,model construction,and conclusion verification,so as to promote the transformation of middle school probability and statistics teaching from knowledge imparting to competency development,and provide a practical reference for curriculum reform.
基金Shaanxi Provincial 14th Five-Year Plan for Educational Science Research(SGH24Q481)。
文摘This paper focuses on the ideological and political construction of the course“Probability Theory and Mathematical Statistics.”Aiming at the current situation in teaching where emphasis is placed on knowledge imparting while value guidance is neglected,and combined with the requirements of ideological and political education policies in the new era,this paper explores the integration path between professional courses and ideological and political education.Through literature analysis,case comparison,and empirical research,the study proposes a systematic implementation plan covering the design of teaching objectives,the reconstruction of teaching content,and the optimization of the evaluation system.The purpose is to cultivate students’sense of social responsibility and innovative awareness by excavating the ideological and political elements in mathematics.The research results provide practical reference for colleges and universities to deepen the reform of ideological and political education in courses,and promote the implementation of the fundamental task of fostering virtue through education in STEM education.
基金partially supported by the National Key Research and Development Project under Grant 2020YFB1806805Science and Technology on Communication Networks Laboratorysupported by China Scholarship Council.
文摘Reconfigurable intelligent surface(RIS)is a promising candidate technology of the upcoming Sixth Generation(6G)communication system for its ability to provide unprecedented spectral and energy efficiency increment through passive beamforming.However,it is challenging to obtain instantaneous channel state information(I-CSI)for RIS,which obliges us to use statistical channel state information(S-CSI)to achieve passive beamforming.In this paper,RIS-aided multiple-input single-output(MISO)multi-user downlink communication system with correlated channels is investigated.Then,we formulate the problem of joint beamforming design at the AP and RIS to maximize the sum ergodic spectral efficiency(ESE)of all users to improve the network capacity.Since it is too hard to compute sum ESE,an ESE approximation is adopted to reformulate the problem into a more tractable form.Then,we present two joint beamforming algorithms,namely the singular value decomposition-gradient descent(SVD-GD)algorithm and the fractional programming-gradient descent(FP-GD)algorithm.Simulation results show the effectiveness of our proposed algorithms and validate that 2-bits quantizer is enough for RIS phase shifts implementation.
文摘The ability to accurately simulate the time evolu-tion of quantum systems stands as a cornerstone of modern molecular science.It provides the essential mechanistic bridge between a system’s microscopic structure and its macroscopic function,a challenge first envisioned by Feynman.The central difficulty,and the unifying theme of this Special Topic,is the problem of“complexity”:a multifaceted challenge arising from the interplay of strongly coupled electronic and vibrational degrees of freedom,quantum statistics,and the non-trivial,often non-Markovian,memory effects exerted by a surrounding environment.
基金supported by the National Science and Technology Major Project(No.2011 ZX05007-006)the 973 Program of China(No.2013CB228604)the Major Project of Petrochina(No.2014B-0610)
文摘Variation of reservoir physical properties can cause changes in its elastic parameters. However, this is not a simple linear relation. Furthermore, the lack of observations, data overlap, noise interference, and idealized models increases the uncertainties of the inversion result. Thus, we propose an inversion method that is different from traditional statistical rock physics modeling. First, we use deterministic and stochastic rock physics models considering the uncertainties of elastic parameters obtained by prestack seismic inversion and introduce weighting coefficients to establish a weighted statistical relation between reservoir and elastic parameters. Second, based on the weighted statistical relation, we use Markov chain Monte Carlo simulations to generate the random joint distribution space of reservoir and elastic parameters that serves as a sample solution space of an objective function. Finally, we propose a fast solution criterion to maximize the posterior probability density and obtain reservoir parameters. The method has high efficiency and application potential.
基金supports from National Natural Science Foundation of China (No. 41406032 and No. 41376014)Open Fund of State Key Laboratory of Satellite Ocean Environment Dynamics (No. SOED1305)
文摘Ocean waves are the core environmental elements affecting the movements and structure design of ships. Statistical analysis of wave parameters is the basis for the establishment of long-term ship environmental adaptability prediction model. The observations from coastal stations, buoys, altimeters and volunteer ships that cover from 1993 to 2011 were interpolated into miller Ion-lat grids by using bilinear method and the analytical fields of ocean waves were given. By using optimal interpolation, the analysis wave fields were assimilated into the WAVEWATCH III （WW3） simulation results. From the assimilated results, the wave rose statistics, the wave height of muitiyear return period and the extreme 2-D wave spectrum are related to the ship seakeeping were calculated. Finally, the wave statistics in China offshore were analyzed in detail.
基金Science and Technology Support Planning of Jiangsu Province(No.BE2014133)the Open Foundation of Key Laboratory of Underw ater Acoustic Signal Processing(No.UASP1301)the Prospective Joint Research Project of Jiangsu province(No.BY2014127-01)
文摘To take into account the influence of uncetainties on the dynamic response of the vibro-acousitc structure, a hybrid modeling technique combining the finite element method（FE）and the statistic energy analysis（SEA） is proposed to analyze vibro-acoustics responses with uncertainties at middle frequencies. The mid-frequency dynamic response of the framework-plate structure with uncertainties is studied based on the hybrid FE-SEA method and the Monte Carlo（MC）simulation is performed so as to provide a benchmark comparison with the hybrid method. The energy response of the framework-plate structure matches well with the MC simulation results, which validates the effectiveness of the hybrid FE-SEA method considering both the complexity of the vibro-acoustic structure and the uncertainties in mid-frequency vibro-acousitc analysis. Based on the hybrid method, a vibroacoustic model of a construction machinery cab with random properties is established, and the excitations of the model are measured by experiments. The responses of the sound pressure level of the cab and the vibration power spectrum density of the front windscreen are calculated and compared with those of the experiment. At middle frequencies, the results have a good consistency with the tests and the prediction error is less than 3. 5dB.
文摘In order to reduce the enormous pressure to environmental monitoring work brought by the false sewage monitoring data, Grubbs method, box plot, t test and other methods are used to make depth analysis to the data, providing a set of technological process to identify the sewage monitoring data, which is convenient and simple.
文摘With the illustration of a specific problem, this paper demonstrates that using Monte Carlo Simulation technology will improve intuitive effect of teaching Probability and Mathematical Statistics course, and save instructors' effort as well.And it is estimated that Monte Carlo Simulation technology will be one of the major teaching methods for Probability and Mathematical Statistics course in the future.
文摘“Four classes of enterprises above designated size”(hereinafter called four-classes enterprises)refer to objects of statistical survey that have reached a certain scale in China’s current statistical method system,including four classes in national economy,namely,industrial enterprises above designated size,construction and real estate development and management enterprises above qualifications,wholesale and retail,catering and accommodation enterprises,and service enterprises above designated size,which are the primary part of national economic and social development activities.This paper is focused on analyzing the practice and difficulties in the current statistics work of four-classes enterprises,and then this paper proposes some recommendations.
文摘AIM To provide a quantitative assessment of theassociation between type 2 diabetes mellitus （T2DM）and the risk of colorectal cancer （CRC）.METHODS： Systematic review was conductedthorough MEDLINE, EMBASE, Cochrane Library, and ISI Web of knowledge databases till 31st January 2014.This meta-analysis included the cohort studies thatillustrated relative risk （RR） or odds ratio estimateswith 95%CI for the predictive risk of CRC by T2DM.Summary relative risks with 95%CI were analyzed byusing an effects summary ratio model. Heterogeneityamong studies was assessed by the Cochran＇s Q and I 2statistics.RESULTS： The meta analysis of 8 finally selectedstudies showed a positive correlation of T2DM withthe risk of CRC as depicted by effects summary RRof 1.21 （95%CI： 1.02-1.42）. Diabetic women showedgreater risk of developing CRC as their effect summaryRR of 1.22 （95%CI： 1.01-49） with significant overallZ test at 5% level of significance was higher than theeffect summary RR of 1.17 （95%CI： 1.00-1.37） of menshowing insignificant Z test. The effect summary RRof 1.19 with 95%CI of 1.07-1.33 indicate a positiverelationship between DM and increased risk of CRCwith significant heterogeneity （I 2 = 92% and P -value 〈0.05）.CONCLUSION： Results from this systematic reviewand meta-analysis report that diabetic people have anincreased risk of CRC as compared to non-diabetics.
