Objective:To analyze the perioperative respiratory care methods and application value in children with congenital heart disease.Methods:60 children with congenital heart disease(treated from January 2021 to October 20...Objective:To analyze the perioperative respiratory care methods and application value in children with congenital heart disease.Methods:60 children with congenital heart disease(treated from January 2021 to October 2023)were screened and divided into two groups randomly.Each group consisted of 30 cases.The perioperative routine was used in the control group.The observation group underwent the perioperative routine along with better respiratory care.Oxygenation indicators,surgical complications,and family satisfaction levels of the groups were compared.Results:There was no significant difference in the oxygenation index between the two groups of children at admission(P>0.05).At discharge,the oxygenation indicators in the observation group were better than those of the control group,and the incidence of surgical complications was lower than that of the control group.The total satisfaction of family members in the observation group was higher than that of the control group(P<0.05).Conclusion:During the perioperative period for children with congenital heart disease,the implementation of respiratory care,which mainly involves symptomatic care,catheter care,sputum suction care,etc.,can actively improve the oxygenation indicators,reduce surgical complications,and promote faster and better recovery,of children with congenital heart disease.展开更多
The technology of drilling tests makes it possible to obtain the strength parameter of rock accurately in situ. In this paper, a new rock cutting analysis model that considers the influence of the rock crushing zone(R...The technology of drilling tests makes it possible to obtain the strength parameter of rock accurately in situ. In this paper, a new rock cutting analysis model that considers the influence of the rock crushing zone(RCZ) is built. The formula for an ultimate cutting force is established based on the limit equilibrium principle. The relationship between digital drilling parameters(DDP) and the c-φ parameter(DDP-cφ formula, where c refers to the cohesion and φ refers to the internal friction angle) is derived, and the response of drilling parameters and cutting ratio to the strength parameters is analyzed. The drillingbased measuring method for the c-φ parameter of rock is constructed. The laboratory verification test is then completed, and the difference in results between the drilling test and the compression test is less than 6%. On this basis, in-situ rock drilling tests in a traffic tunnel and a coal mine roadway are carried out, and the strength parameters of the surrounding rock are effectively tested. The average difference ratio of the results is less than 11%, which verifies the effectiveness of the proposed method for obtaining the strength parameters based on digital drilling. This study provides methodological support for field testing of rock strength parameters.展开更多
To solve the Laplacian problems,we adopt a meshless method with the multiquadric radial basis function(MQRBF)as a basis whose center is distributed inside a circle with a fictitious radius.A maximal projection techniq...To solve the Laplacian problems,we adopt a meshless method with the multiquadric radial basis function(MQRBF)as a basis whose center is distributed inside a circle with a fictitious radius.A maximal projection technique is developed to identify the optimal shape factor and fictitious radius by minimizing a merit function.A sample function is interpolated by theMQ-RBF to provide a trial coefficient vector to compute the merit function.We can quickly determine the optimal values of the parameters within a preferred rage using the golden section search algorithm.The novel method provides the optimal values of parameters and,hence,an optimal MQ-RBF;the performance of the method is validated in numerical examples.Moreover,nonharmonic problems are transformed to the Poisson equation endowed with a homogeneous boundary condition;this can overcome the problem of these problems being ill-posed.The optimal MQ-RBF is extremely accurate.We further propose a novel optimal polynomial method to solve the nonharmonic problems,which achieves high precision up to an order of 10^(−11).展开更多
Based on a total of 16 indicators selected from the tourism and transport industries,an evaluation index system of the coupling and coordination development level of tourism and transport is constructed.The entropy va...Based on a total of 16 indicators selected from the tourism and transport industries,an evaluation index system of the coupling and coordination development level of tourism and transport is constructed.The entropy value method and the coupling coordination degree model are used to conduct an empirical study on the development level and coupling coordination level of the transport and tourism industries in Chengdu City from 2011 to 2020.The results show that,on the whole,the coupling coordination degree of transport and tourism in Chengdu is poor and has been in a state of mild to moderate dysfunction.The development level of tourism lagged behind the development of transport from 2011 to 2012,and the two were in a state of mild dysfunction.However,from 2013 onwards,the development level of tourism was prioritized over the development level of transport.This shift caused the coupling coordination degree of the two industries to decline sharply to 0.23305 in 2013.The development level of the tourism industry increased again,reaching 0.34206 in 2019,which marked an improvement.Consequently,the coordination degree of the transport and tourism industries evolved from moderate dislocation to mild dislocation.Finally,the results of the empirical research are analyzed,and corresponding suggestions are put forward to promote the sustainable growth of the transport and tourism industries in Chengdu City.These suggestions aim to improve the coupled and coordinated development level of the two industries.展开更多
In dielectrometry,traditional analytical and numerical algorithms are difficultly employed in complex resonant cavities.For a special kind of structure(a rotating resonant cavity),the body of revolution finite-element...In dielectrometry,traditional analytical and numerical algorithms are difficultly employed in complex resonant cavities.For a special kind of structure(a rotating resonant cavity),the body of revolution finite-element method(BOR-FEM)is employed to calculate the resonant parameters and dielectric parameters.In this paper,several typical resonant structures are selected for analysis and verification.Compared with the resonance parameter values in the literature and the simulation results of commercial software,the error of the BOR-FEM calculation is less than 0.9%and a single solution time is less than 1 s.Reentrant coaxial resonant cavities loaded with dielectric materials are analyzed using this method and compared with simulation results,showing good agreement.Finally,in this paper,the established BOR-FEM method is successfully applied with a machined cavity for the accurate measurement of the complex dielectric constant of dielectric materials.The test specimens were machined from polytetrafluoroethylene,fused silica and Al_(2)O_(3),and the test results showed good agreement with the literature reference values.展开更多
This paper presents an enhanced version of the standard shooting method that enables problems with two unknown parameters to be solved.A novel approach is applied to the analysis of the natural vibrations of Euler-Ber...This paper presents an enhanced version of the standard shooting method that enables problems with two unknown parameters to be solved.A novel approach is applied to the analysis of the natural vibrations of Euler-Bernoulli beams.The proposed algorithm,named as two-parameter multiple shooting method,is a new powerful numerical tool for calculating the natural frequencies and modes of multi-segment prismatic and non-prismatic beams with different boundary conditions.The impact of the axial force and additional point masses is also taken into account.Due to the fact that the method is based directly on the fourth-order ordinary differential equation,the structures do not have to be divided into many small elements to obtain an accurate enough solution,even though the geometry is very complex.To verify the proposed method,three different examples are considered,i.e.,a three-segment non-prismatic beam,a prismatic column subject to non-uniformly distributed compressive loads,and a two-segment beam with an additional point mass.Numerical analyses are carried out with the software MATHEMATICA.The results are compared with the solutions computed by the commercial finite element program SOFiSTiK.Good agreement is achieved,which confirms the correctness and high effectiveness of the formulated algorithm.展开更多
The accurate measurement of parameters such as the cavity-loaded quality factor(Q_(L))and half bandwidth(f_(0.5))is essential for monitoring the performance of superconducting radio-frequency cavities.However,the conv...The accurate measurement of parameters such as the cavity-loaded quality factor(Q_(L))and half bandwidth(f_(0.5))is essential for monitoring the performance of superconducting radio-frequency cavities.However,the conventional"field decay method"employed to calibrate these values requires the cavity to satisfy a"zero-input"condition.This can be challenging when the source impedance is mismatched and produce nonzero forward signals(V_(f))that significantly affect the measurement accuracy.To address this limitation,we developed a modified version of the"field decay method"based on the cavity differential equation.The proposed approach enables the precise calibration of f_(0.5) even under mismatch conditions.We tested the proposed approach on the SRF cavities of the Chinese Accelerator-Driven System Front-End Demo Superconducting Linac and compared the results with those obtained from a network analyzer.The two sets of results were consistent,indicating the usefulness of the proposed approach.展开更多
In this study,we develop and empirically test a valuation model for a commonly encountered option in office leases:a tenant’s option to renew at future market rent(a fair market value)with lease termination as the ma...In this study,we develop and empirically test a valuation model for a commonly encountered option in office leases:a tenant’s option to renew at future market rent(a fair market value)with lease termination as the maturity date.The model integrates decision analysis with real options analysis and market risk with private risks.“Option value”is defined as the private value of the option to either party pre-contract,while“option price”assumes a fair agreement between transacting parties and can be positive(rental premium paid)or negative(rental discount offered).Without manifest expectations,an analysis of a sample of office leases supports the model’s logic with price estimates in a practical range.The tenants’option price/value is shown to have a negative relationship with the original/renewal lease term;conversely,the landlords’option value is positively related to the original/renewal term.Comparative analyses show that transaction costs have a positive effect on tenants’option value and on prices,while vacancy costs and the vacancy period are both positively related to the landlords’option value and negatively related to price.Market rent is found to have a negative relationship with option price.Overall,this study provides a theoretical analysis and empirical tests of the value of a real option that allows option holders to renew/extend their contracts at a fair market value.展开更多
The normal distribution, which has a symmetric and middle-tailed profile, is one of the most important distributions in probability theory, parametric inference, and description of quantitative variables. However, the...The normal distribution, which has a symmetric and middle-tailed profile, is one of the most important distributions in probability theory, parametric inference, and description of quantitative variables. However, there are many non-normal distributions and knowledge of a non-zero bias allows their identification and decision making regarding the use of techniques and corrections. Pearson’s skewness coefficient defined as the standardized signed distance from the arithmetic mean to the median is very simple to calculate and clear to interpret from the normal distribution model, making it an excellent measure to evaluate this assumption, complemented with the visual inspection by means of a histogram and a box-and-whisker plot. From its variant without tripling the numerator or Yule’s skewness coefficient, the objective of this methodological article is to facilitate the use of this latter measure, presenting how to obtain asymptotic and bootstrap confidence intervals for its interpretation. Not only are the formulas shown, but they are applied with an example using R program. A general rule of interpretation of ∓0.1 has been suggested, but this can only become relevant when contextualized in relation to sample size and a measure of skewness with a population or parametric value of zero. For this purpose, intervals with confidence levels of 90%, 95% and 99% were estimated with 10,000 draws at random with replacement from 57 normally distributed samples-population with different sample sizes. The article closes with suggestions for the use of this measure of skewness.展开更多
Cruise value chain is to take the exchange of cruise products and services as the core in a certain spatial scope,and enterprises with core advantages within or between different industries establish associations in a...Cruise value chain is to take the exchange of cruise products and services as the core in a certain spatial scope,and enterprises with core advantages within or between different industries establish associations in accordance with certain technical and economic conditions,so as to realise the multi-dimensional extension and value appreciation of the cruise value chain in the vertical and horizontal links,and ultimately establish a chain-network type of enterprise strategic alliance.This paper tries to analyse the value-added factors of the cruise industry chain by constructing a multi-level hierarchical structural model with reference to the influencing factor analysis methods of relevant literature-DEMATEL(Decision Making Experiment and Evaluation Experiment)and ISM(Interpretative Structural Model).The study shows that the innovation and scale value-added module in the upstream of the cruise industry chain is the core module of value-added of the whole cruise industry chain,and the value-added mainly originates from the design and manufacturing of cruise ships.The middle reaches of the cruise industry chain are mainly cruise operation enterprises,and the specificity of cruise operation determines that its brand value-added is mainly accomplished through the global layout of multinational corporations,and the cruise brand is able to drive the consumption demand and has value-added ability.The downstream value-added of the cruise industry chain is mainly realised through the increase in profits of cruise tourism service products.展开更多
Since the introduction of the concept, studies on valuation of ecosystem services have been overwhelming, in cognizance of its great significance. In this article, the authors took Northeast China as the study area an...Since the introduction of the concept, studies on valuation of ecosystem services have been overwhelming, in cognizance of its great significance. In this article, the authors took Northeast China as the study area and applied the published coefficients for the world by Costanza to calculate the ecosystem services values through a spatial convolution method. The convolution analysis was done with a square processor with 5×5 neighborhood cells. The results showed that the ecosystem services value for the study area in the year 2003 was US$44 990 million which is US$89 million less than the value without operation, and the main contributions for that decrease were from water bodies, wetlands and estuaries. It is expected that this article can attract more interest to explore this field adopting geographic methods.展开更多
To reduce the stitching error of circularity measurement of small cylindrical workpieces(Diameter less than 3 mm)by the segmenting-stitching method,arc contour extraction is analyzed in this paper.The coordinates of c...To reduce the stitching error of circularity measurement of small cylindrical workpieces(Diameter less than 3 mm)by the segmenting-stitching method,arc contour extraction is analyzed in this paper.The coordinates of cross-sectional circle of a small cylindrical part are segmented into several equal arcs to be obtained by a two-dimensional coordinate measuring machine.The circularity contour of the small cylindrical part can be formed by stitching a series of arc contours which are calculated by the obtained arc coordinate data.Due to the different measuring pressure angles of different measuring positions,the accuracy of obtained arc coordinate points is different.The bigger the pressure angle is,the accurate the obtained arc coordinate data are.The experiments show that the accuracy of two ends of the arc data is not as good as the central part.Therefore,the two ends of the obtained arc data are appropriately to be cut off,namely,only the central part of the arc data are extracted to be used for the stitching.As a result,the mean value of the matching coefficient is enhanced by 12%,the deviation between the overlap part of the neighbouring arc contour is reduced by 26%,and the average curvature of the arc contours is improved with the extraction method.Thus,the accuracy of the stitched circularity contour can be improved by this extraction procedure in the segmenting-stitching method for the circularity measurement of the small cylindrical parts.展开更多
International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to me...International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to measure the risks of international oil and gas projects. For this purpose, this paper constructs a probabilistic model that is based on the traditional economic evaluation model, and introduces value at risk(VaR) which is a valuable risk measure tool in finance, and applies Va R to measure the risks of royalty contracts, production share contracts and service contracts of an international oil and gas project. Besides, this paper compares the influences of different risk factors on the net present value(NPV) of the project by using the simulation results. The results indicate:(1) risks have great impacts on the project's NPV, therefore, if risks are overlooked, the decision may be wrong.(2) A simulation method is applied to simulate the stochastic distribution of risk factors in the probabilistic model. Therefore, the probability is related to the project's NPV, overcoming the inherent limitation of the traditional economic evaluation method.(3) VaR is a straightforward risk measure tool, and can be applied to evaluate the risks of international oil and gas projects. It is helpful for decision making.展开更多
Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. ...Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. A circular zone counting (CZC) method is proposed in this paper, by combining the Duffing oscillator's phase trajectory feature and numerical calculation for quickly and accurately identifying state transition and determining the critical value, to realize a high- efficiency weak signal detection. Detailed model analysis and method construction of the CZC method are introduced. Numerical experiments into the reliability of the proposed CZC method compared with the maximum Lyapunov exponent (MLE) method are carried out. The CZC method is demonstrated to have better detecting ability than the MLE method, and furthermore it is simpler and clearer in calculation to extend to engineering application.展开更多
Objective: We adopted the area under the curve (AUC) of oral glucose tolerance test (OGTT) as a measure method of the severity of maternal hyperglycemia and investigated its relationship with adverse perinatal outcome...Objective: We adopted the area under the curve (AUC) of oral glucose tolerance test (OGTT) as a measure method of the severity of maternal hyperglycemia and investigated its relationship with adverse perinatal outcomes among women with and without gestational diabetes mellitus (GDM). Research design and methods: This is a retrospective cohort study. Our study group collected the medical records of 15,296 women who received perinatal care in 15 hospitals in Beijing and who delivered from July 1, 2013, to December 31, 2013. And several original articles on this cohort have been published. In this study, we analyze the relationship between AUC and adverse perinatal outcomes, so that in multiple pregnant cases, patients with pre-pregnancy diabetes, hypertension, and abnormal kidney function and those who did not receive a 75-g OGTT were excluded. A Chi-squared test and logistic regression analysis were used to determine the associations. Results: In total, 13,561 women were included. As the AUC of OGTT increased, the prevalence of macrosomia (odds ratio [OR] 1.059, 95% confidence interval [95% CI] 1.029 - 1.090, p < 0.001) and hypertensive diseases (OR 1.106, 95% CI 1.064 - 1.149, p < 0.001) also increased. For patients with same levels of AUC values, no significant differences in the risk of macrosomia, preterm birth and neonatal complications were observed between the GDM and non-GDM groups. Women with an AUC higher than 14.20 (mmol * h/L) had a higher risk of adverse outcomes regardless of the presence of GDM. Conclusions: The AUC could be a measure method of the severity of maternal hyperglycemia, and women with a high AUC should undergo aggressive management to avoid adverse outcomes regardless of the presence of GDM.展开更多
The current manuscript makes use of the prominent iterative procedure, called the Adomian Decomposition Method (ADM), to tackle some important special differential equations. The equations of curiosity in this study a...The current manuscript makes use of the prominent iterative procedure, called the Adomian Decomposition Method (ADM), to tackle some important special differential equations. The equations of curiosity in this study are the singular equations that arise in many physical science applications. Thus, through the application of the ADM, a generalized recursive scheme was successfully derived and further utilized to obtain closed-form solutions for the models under consideration. The method is, indeed, fascinating as respective exact analytical solutions are accurately acquired with only a small number of iterations.展开更多
In this paper, we firstly define a decreasing sequence {Pn(S)} by the generation of the Sierpinski gasket where each Pn(S) can be obtained in finite steps. Then we prove that the Hausdorff measure Hs(S) of the Sierpin...In this paper, we firstly define a decreasing sequence {Pn(S)} by the generation of the Sierpinski gasket where each Pn(S) can be obtained in finite steps. Then we prove that the Hausdorff measure Hs(S) of the Sierpinski gasket S can be approximated by {Pn(S)} with Pn(S)/(l + l/2n-3)s≤Hs(S)≤ Pn(S). An algorithm is presented to get Pn(S) for n ≤5. As an application, we obtain the best lower bound of Hs(S) till now: Hs(S)≥0.5631.展开更多
This article attempts to investigate the measure effect of rubble roadbed engineering in permafrost regions of Qinghai-Tibet Plateau. As a case study, Chaidaer-Muli Railway is used to evaluate the measure effect of ru...This article attempts to investigate the measure effect of rubble roadbed engineering in permafrost regions of Qinghai-Tibet Plateau. As a case study, Chaidaer-Muli Railway is used to evaluate the measure effect of rubble roadbed engineering in permafrost regions. The AHP(Analytic Hierarchy Process) method is thus employed to establish the evaluation indicator system. The evaluation factor is selected by analyzing the mutual relation between the permafrost environment and roadbed engineering. Thus, a hierarchical structure model is established based on the selected evaluation indices. Each factor is weighted to determine the status in the evaluation system, and grading standards are built for providing a basis for the evaluation. Then, the fuzzy mathematical method is introduced to evaluate the measure effect of rubble roadbed engineering in permafrost regions along the Chadaer-Muli Railway. Results show that most of the permafrost roadbed is in a preferable condition(b) along the Chaidaer-Muli Railway due to rubble engineering measures. This proportion reaches to 86.1%. The proportion in good(a), general(c) and poor states(d) are 0.0%, 7.5% and 6.4%, respectively, in all the evaluation sections along the Chaidaer-Muli Railway. Ground-temperature monitoring results are generally consistent with AHP-FUZZY evaluation results. This means that the AHP-FUZZY method can be applied to evaluate the effect of rubble roadbed engineering measures in permafrost regions. The effect evaluation of engineering measures will provide timely and effective feedback information for further engineering design. The series of engineering measures will more effectively protect permafrost stability.展开更多
The recently proposed interface propagation-based method has shown its advantages in obtaining the thermal conductivity of phase change materials during solid-liquid transition over conventional techniques. However, i...The recently proposed interface propagation-based method has shown its advantages in obtaining the thermal conductivity of phase change materials during solid-liquid transition over conventional techniques. However, in previous investigation, the analysis on the measurement error was qualitative and only focused on the total effects on the measurement without decoupling the influencing factors. This paper discusses the effects of influencing factors on the measurement results for the interface propagation-based method. Numerical simulations were performed to explore the influencing factors, namely model simplification, subcooling and natural convection, along with their impact on the measurement process and corresponding measurement results. The numerical solutions were provided in terms of moving curves of the solid-liquid interface and the predicted values of thermal conductivity. Results indicated that the impact of simplified model was strongly dependent on Stefan number of the melting process. The degree of subcooling would lead to underestimated values for thermal conductivity prediction. The natural convection would intensify the heat transfer rate in the liquid region, thereby overestimating the obtained results of thermal conductivity. Correlations and experimental guidelines are provided. The relative errors are limited in ±1.5%,±3%and ±2% corresponding to the impact of simplified model, subcooling and natural convection, respectively.展开更多
In this article, we give a description of measure-valued processes with interactive stochastic flows. It is a unified construction for superprocesses with dependent spatial motion constructed by Dawson, LI, Wang and s...In this article, we give a description of measure-valued processes with interactive stochastic flows. It is a unified construction for superprocesses with dependent spatial motion constructed by Dawson, LI, Wang and superprocesses of stochastic flows constructed by Ma and Xiang.展开更多
文摘Objective:To analyze the perioperative respiratory care methods and application value in children with congenital heart disease.Methods:60 children with congenital heart disease(treated from January 2021 to October 2023)were screened and divided into two groups randomly.Each group consisted of 30 cases.The perioperative routine was used in the control group.The observation group underwent the perioperative routine along with better respiratory care.Oxygenation indicators,surgical complications,and family satisfaction levels of the groups were compared.Results:There was no significant difference in the oxygenation index between the two groups of children at admission(P>0.05).At discharge,the oxygenation indicators in the observation group were better than those of the control group,and the incidence of surgical complications was lower than that of the control group.The total satisfaction of family members in the observation group was higher than that of the control group(P<0.05).Conclusion:During the perioperative period for children with congenital heart disease,the implementation of respiratory care,which mainly involves symptomatic care,catheter care,sputum suction care,etc.,can actively improve the oxygenation indicators,reduce surgical complications,and promote faster and better recovery,of children with congenital heart disease.
基金supported by the National Key Research and Development Program of China(No.2023YFC2907600)the National Natural Science Foundation of China(Nos.42077267,42277174 and 52074164)+2 种基金the Natural Science Foundation of Shandong Province,China(No.ZR2020JQ23)the Opening Project of State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology(No.KFJJ21-02Z)the Fundamental Research Funds for the Central Universities,China(No.2022JCCXSB03).
文摘The technology of drilling tests makes it possible to obtain the strength parameter of rock accurately in situ. In this paper, a new rock cutting analysis model that considers the influence of the rock crushing zone(RCZ) is built. The formula for an ultimate cutting force is established based on the limit equilibrium principle. The relationship between digital drilling parameters(DDP) and the c-φ parameter(DDP-cφ formula, where c refers to the cohesion and φ refers to the internal friction angle) is derived, and the response of drilling parameters and cutting ratio to the strength parameters is analyzed. The drillingbased measuring method for the c-φ parameter of rock is constructed. The laboratory verification test is then completed, and the difference in results between the drilling test and the compression test is less than 6%. On this basis, in-situ rock drilling tests in a traffic tunnel and a coal mine roadway are carried out, and the strength parameters of the surrounding rock are effectively tested. The average difference ratio of the results is less than 11%, which verifies the effectiveness of the proposed method for obtaining the strength parameters based on digital drilling. This study provides methodological support for field testing of rock strength parameters.
基金supported by the the National Science and Technology Council(Grant Number:NSTC 112-2221-E239-022).
文摘To solve the Laplacian problems,we adopt a meshless method with the multiquadric radial basis function(MQRBF)as a basis whose center is distributed inside a circle with a fictitious radius.A maximal projection technique is developed to identify the optimal shape factor and fictitious radius by minimizing a merit function.A sample function is interpolated by theMQ-RBF to provide a trial coefficient vector to compute the merit function.We can quickly determine the optimal values of the parameters within a preferred rage using the golden section search algorithm.The novel method provides the optimal values of parameters and,hence,an optimal MQ-RBF;the performance of the method is validated in numerical examples.Moreover,nonharmonic problems are transformed to the Poisson equation endowed with a homogeneous boundary condition;this can overcome the problem of these problems being ill-posed.The optimal MQ-RBF is extremely accurate.We further propose a novel optimal polynomial method to solve the nonharmonic problems,which achieves high precision up to an order of 10^(−11).
基金Chongqing University of Science and Technology Postgraduate Innovation Program Project(Project No.YKJCX2320902)。
文摘Based on a total of 16 indicators selected from the tourism and transport industries,an evaluation index system of the coupling and coordination development level of tourism and transport is constructed.The entropy value method and the coupling coordination degree model are used to conduct an empirical study on the development level and coupling coordination level of the transport and tourism industries in Chengdu City from 2011 to 2020.The results show that,on the whole,the coupling coordination degree of transport and tourism in Chengdu is poor and has been in a state of mild to moderate dysfunction.The development level of tourism lagged behind the development of transport from 2011 to 2012,and the two were in a state of mild dysfunction.However,from 2013 onwards,the development level of tourism was prioritized over the development level of transport.This shift caused the coupling coordination degree of the two industries to decline sharply to 0.23305 in 2013.The development level of the tourism industry increased again,reaching 0.34206 in 2019,which marked an improvement.Consequently,the coordination degree of the transport and tourism industries evolved from moderate dislocation to mild dislocation.Finally,the results of the empirical research are analyzed,and corresponding suggestions are put forward to promote the sustainable growth of the transport and tourism industries in Chengdu City.These suggestions aim to improve the coupled and coordinated development level of the two industries.
基金the National Natural Science Foundation of China(Grant No.62001083)the Guangdong Provincial Key Research and Development Project,China(Grant No.2020B010179002).
文摘In dielectrometry,traditional analytical and numerical algorithms are difficultly employed in complex resonant cavities.For a special kind of structure(a rotating resonant cavity),the body of revolution finite-element method(BOR-FEM)is employed to calculate the resonant parameters and dielectric parameters.In this paper,several typical resonant structures are selected for analysis and verification.Compared with the resonance parameter values in the literature and the simulation results of commercial software,the error of the BOR-FEM calculation is less than 0.9%and a single solution time is less than 1 s.Reentrant coaxial resonant cavities loaded with dielectric materials are analyzed using this method and compared with simulation results,showing good agreement.Finally,in this paper,the established BOR-FEM method is successfully applied with a machined cavity for the accurate measurement of the complex dielectric constant of dielectric materials.The test specimens were machined from polytetrafluoroethylene,fused silica and Al_(2)O_(3),and the test results showed good agreement with the literature reference values.
文摘This paper presents an enhanced version of the standard shooting method that enables problems with two unknown parameters to be solved.A novel approach is applied to the analysis of the natural vibrations of Euler-Bernoulli beams.The proposed algorithm,named as two-parameter multiple shooting method,is a new powerful numerical tool for calculating the natural frequencies and modes of multi-segment prismatic and non-prismatic beams with different boundary conditions.The impact of the axial force and additional point masses is also taken into account.Due to the fact that the method is based directly on the fourth-order ordinary differential equation,the structures do not have to be divided into many small elements to obtain an accurate enough solution,even though the geometry is very complex.To verify the proposed method,three different examples are considered,i.e.,a three-segment non-prismatic beam,a prismatic column subject to non-uniformly distributed compressive loads,and a two-segment beam with an additional point mass.Numerical analyses are carried out with the software MATHEMATICA.The results are compared with the solutions computed by the commercial finite element program SOFiSTiK.Good agreement is achieved,which confirms the correctness and high effectiveness of the formulated algorithm.
基金supported by the project of Large Research Infrastructures"China initiative Accelerator-Driven System"(No.2017-000052-75-01-000590)"Studies of intelligent LLRF control algorithms for superconducting RF cavities"(No.E129851YR0)the National Natural Science Foundation of China(No.12205344).
文摘The accurate measurement of parameters such as the cavity-loaded quality factor(Q_(L))and half bandwidth(f_(0.5))is essential for monitoring the performance of superconducting radio-frequency cavities.However,the conventional"field decay method"employed to calibrate these values requires the cavity to satisfy a"zero-input"condition.This can be challenging when the source impedance is mismatched and produce nonzero forward signals(V_(f))that significantly affect the measurement accuracy.To address this limitation,we developed a modified version of the"field decay method"based on the cavity differential equation.The proposed approach enables the precise calibration of f_(0.5) even under mismatch conditions.We tested the proposed approach on the SRF cavities of the Chinese Accelerator-Driven System Front-End Demo Superconducting Linac and compared the results with those obtained from a network analyzer.The two sets of results were consistent,indicating the usefulness of the proposed approach.
基金research grants(P0030199 and P0038209)from the Hong Kong Polytechnic University。
文摘In this study,we develop and empirically test a valuation model for a commonly encountered option in office leases:a tenant’s option to renew at future market rent(a fair market value)with lease termination as the maturity date.The model integrates decision analysis with real options analysis and market risk with private risks.“Option value”is defined as the private value of the option to either party pre-contract,while“option price”assumes a fair agreement between transacting parties and can be positive(rental premium paid)or negative(rental discount offered).Without manifest expectations,an analysis of a sample of office leases supports the model’s logic with price estimates in a practical range.The tenants’option price/value is shown to have a negative relationship with the original/renewal lease term;conversely,the landlords’option value is positively related to the original/renewal term.Comparative analyses show that transaction costs have a positive effect on tenants’option value and on prices,while vacancy costs and the vacancy period are both positively related to the landlords’option value and negatively related to price.Market rent is found to have a negative relationship with option price.Overall,this study provides a theoretical analysis and empirical tests of the value of a real option that allows option holders to renew/extend their contracts at a fair market value.
文摘The normal distribution, which has a symmetric and middle-tailed profile, is one of the most important distributions in probability theory, parametric inference, and description of quantitative variables. However, there are many non-normal distributions and knowledge of a non-zero bias allows their identification and decision making regarding the use of techniques and corrections. Pearson’s skewness coefficient defined as the standardized signed distance from the arithmetic mean to the median is very simple to calculate and clear to interpret from the normal distribution model, making it an excellent measure to evaluate this assumption, complemented with the visual inspection by means of a histogram and a box-and-whisker plot. From its variant without tripling the numerator or Yule’s skewness coefficient, the objective of this methodological article is to facilitate the use of this latter measure, presenting how to obtain asymptotic and bootstrap confidence intervals for its interpretation. Not only are the formulas shown, but they are applied with an example using R program. A general rule of interpretation of ∓0.1 has been suggested, but this can only become relevant when contextualized in relation to sample size and a measure of skewness with a population or parametric value of zero. For this purpose, intervals with confidence levels of 90%, 95% and 99% were estimated with 10,000 draws at random with replacement from 57 normally distributed samples-population with different sample sizes. The article closes with suggestions for the use of this measure of skewness.
基金Tropical Ocean University 2023 Provincial Key Discipline Construction Project-Business Administration.Project of the National Social Science Foundation:Research on the Cooperation Mechanism and Realisation Path for the Cooperative Development of the Cruise Industry in the Countries Surrounding the South China Sea(19XJY001)Key Laboratory of the Ministry of Culture and Tourism on Data Mining,Monitoring and Early Warning Technology for Island Tourism Resources(KLITRDMM 2022-15).
文摘Cruise value chain is to take the exchange of cruise products and services as the core in a certain spatial scope,and enterprises with core advantages within or between different industries establish associations in accordance with certain technical and economic conditions,so as to realise the multi-dimensional extension and value appreciation of the cruise value chain in the vertical and horizontal links,and ultimately establish a chain-network type of enterprise strategic alliance.This paper tries to analyse the value-added factors of the cruise industry chain by constructing a multi-level hierarchical structural model with reference to the influencing factor analysis methods of relevant literature-DEMATEL(Decision Making Experiment and Evaluation Experiment)and ISM(Interpretative Structural Model).The study shows that the innovation and scale value-added module in the upstream of the cruise industry chain is the core module of value-added of the whole cruise industry chain,and the value-added mainly originates from the design and manufacturing of cruise ships.The middle reaches of the cruise industry chain are mainly cruise operation enterprises,and the specificity of cruise operation determines that its brand value-added is mainly accomplished through the global layout of multinational corporations,and the cruise brand is able to drive the consumption demand and has value-added ability.The downstream value-added of the cruise industry chain is mainly realised through the increase in profits of cruise tourism service products.
基金funded by the Major Program of National Natural Science Foundation of China (40930101)National Technology Introduction Program of China (948 Program,2009-Z31)the Key Project of the Commonweal Foundation of China's National Academy (2010-02)~~
文摘Since the introduction of the concept, studies on valuation of ecosystem services have been overwhelming, in cognizance of its great significance. In this article, the authors took Northeast China as the study area and applied the published coefficients for the world by Costanza to calculate the ecosystem services values through a spatial convolution method. The convolution analysis was done with a square processor with 5×5 neighborhood cells. The results showed that the ecosystem services value for the study area in the year 2003 was US$44 990 million which is US$89 million less than the value without operation, and the main contributions for that decrease were from water bodies, wetlands and estuaries. It is expected that this article can attract more interest to explore this field adopting geographic methods.
基金supported by the National Defense Basic Scientific Research Program of China(Grant numbers JCKY2019427D002)
文摘To reduce the stitching error of circularity measurement of small cylindrical workpieces(Diameter less than 3 mm)by the segmenting-stitching method,arc contour extraction is analyzed in this paper.The coordinates of cross-sectional circle of a small cylindrical part are segmented into several equal arcs to be obtained by a two-dimensional coordinate measuring machine.The circularity contour of the small cylindrical part can be formed by stitching a series of arc contours which are calculated by the obtained arc coordinate data.Due to the different measuring pressure angles of different measuring positions,the accuracy of obtained arc coordinate points is different.The bigger the pressure angle is,the accurate the obtained arc coordinate data are.The experiments show that the accuracy of two ends of the arc data is not as good as the central part.Therefore,the two ends of the obtained arc data are appropriately to be cut off,namely,only the central part of the arc data are extracted to be used for the stitching.As a result,the mean value of the matching coefficient is enhanced by 12%,the deviation between the overlap part of the neighbouring arc contour is reduced by 26%,and the average curvature of the arc contours is improved with the extraction method.Thus,the accuracy of the stitched circularity contour can be improved by this extraction procedure in the segmenting-stitching method for the circularity measurement of the small cylindrical parts.
基金supported by the Young Fund of Shanxi University of Finance and Economics(No.QN-2018002)National Natural Science Foundation of China(No.71774105)the Fund for Shanxi Key Subjects Construction(FSKSC)and Shanxi Repatriate Study Abroad Foundation(No.2016-3)
文摘International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to measure the risks of international oil and gas projects. For this purpose, this paper constructs a probabilistic model that is based on the traditional economic evaluation model, and introduces value at risk(VaR) which is a valuable risk measure tool in finance, and applies Va R to measure the risks of royalty contracts, production share contracts and service contracts of an international oil and gas project. Besides, this paper compares the influences of different risk factors on the net present value(NPV) of the project by using the simulation results. The results indicate:(1) risks have great impacts on the project's NPV, therefore, if risks are overlooked, the decision may be wrong.(2) A simulation method is applied to simulate the stochastic distribution of risk factors in the probabilistic model. Therefore, the probability is related to the project's NPV, overcoming the inherent limitation of the traditional economic evaluation method.(3) VaR is a straightforward risk measure tool, and can be applied to evaluate the risks of international oil and gas projects. It is helpful for decision making.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61172047 and 61071025)
文摘Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. A circular zone counting (CZC) method is proposed in this paper, by combining the Duffing oscillator's phase trajectory feature and numerical calculation for quickly and accurately identifying state transition and determining the critical value, to realize a high- efficiency weak signal detection. Detailed model analysis and method construction of the CZC method are introduced. Numerical experiments into the reliability of the proposed CZC method compared with the maximum Lyapunov exponent (MLE) method are carried out. The CZC method is demonstrated to have better detecting ability than the MLE method, and furthermore it is simpler and clearer in calculation to extend to engineering application.
文摘Objective: We adopted the area under the curve (AUC) of oral glucose tolerance test (OGTT) as a measure method of the severity of maternal hyperglycemia and investigated its relationship with adverse perinatal outcomes among women with and without gestational diabetes mellitus (GDM). Research design and methods: This is a retrospective cohort study. Our study group collected the medical records of 15,296 women who received perinatal care in 15 hospitals in Beijing and who delivered from July 1, 2013, to December 31, 2013. And several original articles on this cohort have been published. In this study, we analyze the relationship between AUC and adverse perinatal outcomes, so that in multiple pregnant cases, patients with pre-pregnancy diabetes, hypertension, and abnormal kidney function and those who did not receive a 75-g OGTT were excluded. A Chi-squared test and logistic regression analysis were used to determine the associations. Results: In total, 13,561 women were included. As the AUC of OGTT increased, the prevalence of macrosomia (odds ratio [OR] 1.059, 95% confidence interval [95% CI] 1.029 - 1.090, p < 0.001) and hypertensive diseases (OR 1.106, 95% CI 1.064 - 1.149, p < 0.001) also increased. For patients with same levels of AUC values, no significant differences in the risk of macrosomia, preterm birth and neonatal complications were observed between the GDM and non-GDM groups. Women with an AUC higher than 14.20 (mmol * h/L) had a higher risk of adverse outcomes regardless of the presence of GDM. Conclusions: The AUC could be a measure method of the severity of maternal hyperglycemia, and women with a high AUC should undergo aggressive management to avoid adverse outcomes regardless of the presence of GDM.
文摘The current manuscript makes use of the prominent iterative procedure, called the Adomian Decomposition Method (ADM), to tackle some important special differential equations. The equations of curiosity in this study are the singular equations that arise in many physical science applications. Thus, through the application of the ADM, a generalized recursive scheme was successfully derived and further utilized to obtain closed-form solutions for the models under consideration. The method is, indeed, fascinating as respective exact analytical solutions are accurately acquired with only a small number of iterations.
文摘In this paper, we firstly define a decreasing sequence {Pn(S)} by the generation of the Sierpinski gasket where each Pn(S) can be obtained in finite steps. Then we prove that the Hausdorff measure Hs(S) of the Sierpinski gasket S can be approximated by {Pn(S)} with Pn(S)/(l + l/2n-3)s≤Hs(S)≤ Pn(S). An algorithm is presented to get Pn(S) for n ≤5. As an application, we obtain the best lower bound of Hs(S) till now: Hs(S)≥0.5631.
基金supported by the National Natural Science Foundation of China (Nos. 41501079 and 91647103)the self-determined Project Funded by State Key Laboratory of Frozen Soil Engineering (No. SKLFSE-ZQ-43)the Foundation for Excellent Youth Scholars of NIEER, CAS
文摘This article attempts to investigate the measure effect of rubble roadbed engineering in permafrost regions of Qinghai-Tibet Plateau. As a case study, Chaidaer-Muli Railway is used to evaluate the measure effect of rubble roadbed engineering in permafrost regions. The AHP(Analytic Hierarchy Process) method is thus employed to establish the evaluation indicator system. The evaluation factor is selected by analyzing the mutual relation between the permafrost environment and roadbed engineering. Thus, a hierarchical structure model is established based on the selected evaluation indices. Each factor is weighted to determine the status in the evaluation system, and grading standards are built for providing a basis for the evaluation. Then, the fuzzy mathematical method is introduced to evaluate the measure effect of rubble roadbed engineering in permafrost regions along the Chadaer-Muli Railway. Results show that most of the permafrost roadbed is in a preferable condition(b) along the Chaidaer-Muli Railway due to rubble engineering measures. This proportion reaches to 86.1%. The proportion in good(a), general(c) and poor states(d) are 0.0%, 7.5% and 6.4%, respectively, in all the evaluation sections along the Chaidaer-Muli Railway. Ground-temperature monitoring results are generally consistent with AHP-FUZZY evaluation results. This means that the AHP-FUZZY method can be applied to evaluate the effect of rubble roadbed engineering measures in permafrost regions. The effect evaluation of engineering measures will provide timely and effective feedback information for further engineering design. The series of engineering measures will more effectively protect permafrost stability.
基金Project(51606224) supported by the National Natural Science Foundation of China
文摘The recently proposed interface propagation-based method has shown its advantages in obtaining the thermal conductivity of phase change materials during solid-liquid transition over conventional techniques. However, in previous investigation, the analysis on the measurement error was qualitative and only focused on the total effects on the measurement without decoupling the influencing factors. This paper discusses the effects of influencing factors on the measurement results for the interface propagation-based method. Numerical simulations were performed to explore the influencing factors, namely model simplification, subcooling and natural convection, along with their impact on the measurement process and corresponding measurement results. The numerical solutions were provided in terms of moving curves of the solid-liquid interface and the predicted values of thermal conductivity. Results indicated that the impact of simplified model was strongly dependent on Stefan number of the melting process. The degree of subcooling would lead to underestimated values for thermal conductivity prediction. The natural convection would intensify the heat transfer rate in the liquid region, thereby overestimating the obtained results of thermal conductivity. Correlations and experimental guidelines are provided. The relative errors are limited in ±1.5%,±3%and ±2% corresponding to the impact of simplified model, subcooling and natural convection, respectively.
基金Foundation item: Support by the Natural Science Foundation of Henan Province(2004601018)
文摘In this article, we give a description of measure-valued processes with interactive stochastic flows. It is a unified construction for superprocesses with dependent spatial motion constructed by Dawson, LI, Wang and superprocesses of stochastic flows constructed by Ma and Xiang.