AIM: To compare the functional outcomes of patients who underwent open surgery vs Ponseti method for the management of idiopathic clubfoot and to determine whether correlations exist between functional outcome and rad...AIM: To compare the functional outcomes of patients who underwent open surgery vs Ponseti method for the management of idiopathic clubfoot and to determine whether correlations exist between functional outcome and radiographic measurements.METHODS: A meta-analysis of the literature was conducted for studies concerning primary treatment of patients with idiopathic clubfoot. We searched PubM ed Medline, EMBASE, and the Cochrane Library databases from January 1950 to October 2011. Meta-analyses were performed on outcomes from 12 studies. Pooled means, SDs, and sample sizes were either identified in the results or calculated based on the results of each study.RESULTS: Overall, 835 treated idiopathic clubfeet in 516 patients were reviewed. The average follow-up was 15.7 years. Patients managed with Ponseti method did have a higher rate of excellent or good outcome than patients treated with open surgery(0.76 and 0.62, respectively), but not quite to the point of statistical significance(Q = 3.73, P = 0.053). Age at surgery wasnot correlated with the functional outcome for the surgically treated patients(r =-0.32, P = 0.68). A larger anteroposterior talocalcaneal angle was correlated with a higher rate of excellent or good outcomes(r = 0.80, P = 0.006). There were no other significant correlations between the functional and radiographic outcomes.CONCLUSION: The Ponseti method should be considered the initial treatment of idiopathic clubfeet, and open surgery should be reserved for clubfeet that cannot be completely corrected.展开更多
Natural gas hydrate(NGH),considered as a type of premium energy alternative to conventional hydrocarbons,has been broadly studied.The estimate of the total NGH resources in the world has decreased by more than 90%sinc...Natural gas hydrate(NGH),considered as a type of premium energy alternative to conventional hydrocarbons,has been broadly studied.The estimate of the total NGH resources in the world has decreased by more than 90%since the first evaluation in 1973.Geographic and geophysical conditions of the South China Sea(SCS)are favorable for the formation of NGH,which has been proved by drilling results up to date.The recoverability of the NGH in the SCS has been confirmed by the production tests using both vertical and horizontal wells.Since 2001,35 estimates of NGH resources in the SCS have been made,with relatively stable results varying between 600 and 900×109 ton oil equivalent.In these estimations,the volumetric method was commonly adopted,but the geological conditions,the migration-accumulation mechanisms of NGH,and the practical recoverability were not considered.These estimates cannot be regarded as evaluated resources according to the international resource evaluation standards,but are at most about prospective gas content of NGH,thus inefficient for guiding explorations and developments.To solve these problems,this study divides the past NGH surveys in the SCS into seven stages,acquires key geological parameters of every stage based on previous studies and analogy with other areas,evaluates the NGH resources of these seven stages by using the volumetric method,then adopts a new trend-analysis method to simulate the downward trend of these estimates,and finally predicts the NGH resources in the SCS at 2025 and 2030.The downward trend is because of the continuous improvement of NGH understanding over time,which is consistent with the trend of global NGH estimates.At the present stage(from 2019 to 2021),the average technically recoverable resource(ATRR)is 7.0×10^(12)m^(3),and the estimates of 2025 and 2030 ATRR are 6.46×10^(12)m^(3) and 4.01×10^(12)m^(3)respectively,with a difference of less than 40%.Therefore,it can be inferred that the ATRR of NGH in the SCS is between 4.0 and 6.5×10^(12)m^(3),with an average of 5.25×10^(12)m^(3).展开更多
OBJECTIVE： To evaluate the effectiveness and safety of the Xingnao Kaiqiao needling method for treating acute ischemic stroke.DATA SOURCES： We retrieved relevant randomized controlled trials involving Xingnao Kaiqia...OBJECTIVE： To evaluate the effectiveness and safety of the Xingnao Kaiqiao needling method for treating acute ischemic stroke.DATA SOURCES： We retrieved relevant randomized controlled trials involving Xingnao Kaiqiao acupuncture for treatment of acute ischemic stroke. The China National Knowledge Infrastructure, Weipu Information Resources System, Wanfang Medical Data System, Chinese Biomedical Literature Database, Cochrane Library, and Pub Med were searched from June 2006 to March 2016.DATA SELECTION： We analyzed randomized and semi-randomized clinical controlled trials that compared Xingnao Kaiqiao acupuncture with various control treatments, such as conventional drugs or other acupuncture therapies, for treatment of acute ischemic stroke. The quality of articles was evaluated according to the Cochrane Handbook for Systematic Reviews of Interventions（Version 5.1）, and the study was carried out using Cochrane system assessment methods. Rev Man 5.2 was used for the meta-analysis of the included studies.OUTCOME MEASURES： The mortality rate, disability rate, activities of daily living（Barthel Index）, and clinical efficacy were observed.RESULTS： Twelve studies met the inclusion criteria for this review. The meta-analysis showed that between Xingnao Kaiqiao acupuncture and the control treatment, Xingnao Kaiqiao acupuncture reduced the disability rate [risk ratio（RR） = 0.51, 95% confidence interval（CI） = 0.27-0.98, z = 2.03, P 〈 0.05], elevated the activities of daily living（weighted mean difference = 12.23, 95% CI： 3.66-20.08, z = 2.80, P 〈 0.005）, and had greater clinical efficacy（RR = 1.61, 95% CI： 1.23-2.09, z = 3.53, P 〈 0.0004）. However, there was no significant difference in mortality rate（RR = 0.61, 95% CI： 0.15-2.45, z = 0.70, P 〉 0.05）. CONCLUSION： The Xingnao Kaiqiao needling method is effective and safe for acute ischemic stroke. However, there was selective bias in this study, and the likelihood of measurement bias is high. Thus, more high-quality randomized controlled trials are needed to provide reliable evidence of the efficacy and safety of Xingnao Kaiqiao acupuncture in the treatment of acute ischemic stroke.展开更多
Objective:Skill competence is essential for nursing students and experiential teaching method has become increasingly popular in China’s nursing education.To systematically evaluate the effects of experiential teachi...Objective:Skill competence is essential for nursing students and experiential teaching method has become increasingly popular in China’s nursing education.To systematically evaluate the effects of experiential teaching method on the development of nursing students’skill competence,and to provide evidence for nursing education.Methods:The China National Knowledge Infrastructure,VIP,Wanfang Data,PubMed,and Web of Science databases were searched from their inception until November 28,2019.We screened the studies according to inclusion and exclusion criteria,extracted the data,and assessed the quality.Then,a meta-analysis was conducted.Results:Totally 15 studies were included,and 1,633 nursing students were analyzed by Review Manager5.3 and Stata15.1 software.The results show that the experiential teaching method can significantly improve nursing students’nursing skills such as training(SMD=1.05,95%CI:0.95–1.16,P=0.000),learning interest(ES=0.93,95%CI:0.79–1.06),ability to analyze and solve problems(ES=0.75,95%CI:0.55–0.94),ability to judge and innovative thinking(ES=1.01,95%CI:0.77–1.25),abilities of understanding and perception(ES=0.59,95%CI:0.34–0.83),and teaching satisfaction(ES=1.26,95%CI:1.13–1.4).Conclusions:The results suggest that the experiential teaching method is more effective for the nursing students’skill competence than traditional teaching in China.However,due to the heterogeneity and bias risk,a large sample and high-quality studies are needed in future to confirm its effectiveness.展开更多
The separation-of-variable(SOV)methods,such as the improved SOV method,the variational SOV method,and the extended SOV method,have been proposed by the present authors and coworkers to obtain the closed-form analytica...The separation-of-variable(SOV)methods,such as the improved SOV method,the variational SOV method,and the extended SOV method,have been proposed by the present authors and coworkers to obtain the closed-form analytical solutions for free vibration and eigenbuckling of rectangular plates and circular cylindrical shells.By taking the free vibration of rectangular thin plates as an example,this work presents the theoretical framework of the SOV methods in an instructive way,and the bisection–based solution procedures for a group of nonlinear eigenvalue equations.Besides,the explicit equations of nodal lines of the SOV methods are presented,and the relations of nodal line patterns and frequency orders are investigated.It is concluded that the highly accurate SOV methods have the same accuracy for all frequencies,the mode shapes about repeated frequencies can also be precisely captured,and the SOV methods do not have the problem of missing roots as well.展开更多
Objective:This article uses a meta-analysis system to evaluate the clinical efficacy of the method of spleen-invigorating,kidney-tonifying and blood-activating combined with western medicine in the treatment of diabet...Objective:This article uses a meta-analysis system to evaluate the clinical efficacy of the method of spleen-invigorating,kidney-tonifying and blood-activating combined with western medicine in the treatment of diabetic nephropathy,in order to provide evidence-based medicine for the clinical treatment of this disease.Methods:Computer search(January 2009 to June 2020)published in CNKI,Wanfang database,and Weipu Chinese Science and Technology Journal Database with simple western medicine conventional treatment(control group)and on the basis of control group Randomized Controlled Trial(RCT)of the treatment of diabetic nephropathy with spleen-invigorating,kidney-tonifying and blood-activating(experimental group),and manual retrieval of relevant literature that meets the inclusion criteria.Two researchers independently carried out literature screening,and used the improved Jadad rating scale for quality evaluation,and finally used RevMan5.3 statistical software for meta-analysis.Results:A total of 15 randomized controlled trials were included,with a total of 1218 patients,including 621 in the experimental group and 597 in the control group.Meta-analysis showed that the experimental group was improving clinical efficacy(OR=4.35,95%CI[3.12,6.08],P<0.00001),FPG(MD=-0.49,95%CI[-0.89,-0.09],P=0.02),24h urine protein quantification(MD=-0.54,95%CI[-0.90,-0.18],P=0.003),mALB(MD=-15.95,95%CI[-18.12,-13.79],P<0.0001),BUN(MD=-1.79,95%CI[-2.99,-0.59],P=0.004),SCr(MD=-47.63,95%CI[-83.43,-11.83],P=0.009),TC(MD=-1.02,95%CI[-1.42,-0.62],P<0.00001),etc.may be better than the control group;The test group is improving TG(MD=-1.02,95%CI[-1.42,-0.62],P<0.00001)there is no significant difference compared with the control group.Conclusion:The method of spleen-invigorating,kidney-tonifying and blood-activating combined with conventional western medicine treatment of diabetic nephropathy may be superior to conventional western medicine treatment in terms of improving clinical efficacy,FPG,24h urine protein quantification,mALB,BUN,SCr,TC,etc.However,due to the small number and low quality of the literature included in this study,more in-depth research needs to further expand the sample size and include higher quality RCTs.展开更多
This study aims to develop a chloride diffusion simulation method that considers the hydration microstructure and pore solution properties during the hydration of tricalcium silicate(C3S).The method combines the hydra...This study aims to develop a chloride diffusion simulation method that considers the hydration microstructure and pore solution properties during the hydration of tricalcium silicate(C3S).The method combines the hydration simulation,thermodynamic calculation,and finite element analysis to examine the effects of pore solution,including effect of electrochemical potential,effect of chemical activity,and effect of mechanical interactions between ions,on the chloride effective diffusion coefficient of hydrated C3S paste.The results indicate that the effect of electrochemical potential on chloride diffusion becomes stronger with increasing hydration age due to the increase in the content of hydrated calcium silicate;as the hydration age increases,the effect of chemical activity on chloride diffusion weakens when the number of diffusible elements decreases;the effect of mechanical interactions between ions on chloride diffusion decreases with the increase of hydration age.展开更多
To analyze the differences in the transport and distribution of different types of proppants and to address issues such as the short effective support of proppant and poor placement in hydraulically intersecting fract...To analyze the differences in the transport and distribution of different types of proppants and to address issues such as the short effective support of proppant and poor placement in hydraulically intersecting fractures,this study considered the combined impact of geological-engineering factors on conductivity.Using reservoir production parameters and the discrete elementmethod,multispherical proppants were constructed.Additionally,a 3D fracture model,based on the specified conditions of the L block,employed coupled(Computational Fluid Dynamics)CFD-DEM(Discrete ElementMethod)for joint simulations to quantitatively analyze the transport and placement patterns of multispherical proppants in intersecting fractures.Results indicate that turbulent kinetic energy is an intrinsic factor affecting proppant transport.Moreover,the efficiency of placement and migration distance of low-sphericity quartz sand constructed by the DEM in the main fracture are significantly reduced compared to spherical ceramic proppants,with a 27.7%decrease in the volume fraction of the fracture surface,subsequently affecting the placement concentration and damaging fracture conductivity.Compared to small-angle fractures,controlling artificial and natural fractures to expand at angles of 45°to 60°increases the effective support length by approximately 20.6%.During hydraulic fracturing of gas wells,ensuring the fracture support area and post-closure conductivity can be achieved by controlling the sphericity of proppants and adjusting the perforation direction to control the direction of artificial fractures.展开更多
In the independent electro-hydrogen system(IEHS)with hybrid energy storage(HESS),achieving optimal scheduling is crucial.Still,it presents a challenge due to the significant deviations in values ofmultiple optimizatio...In the independent electro-hydrogen system(IEHS)with hybrid energy storage(HESS),achieving optimal scheduling is crucial.Still,it presents a challenge due to the significant deviations in values ofmultiple optimization objective functions caused by their physical dimensions.These deviations seriously affect the scheduling process.A novel standardization fusion method has been established to address this issue by analyzing the variation process of each objective function’s values.The optimal scheduling results of IEHS with HESS indicate that the economy and overall energy loss can be improved 2–3 times under different optimization methods.The proposed method better balances all optimization objective functions and reduces the impact of their dimensionality.When the cost of BESS decreases by approximately 30%,its participation deepens by about 1 time.Moreover,if the price of the electrolyzer is less than 15¥/kWh or if the cost of the fuel cell drops below 4¥/kWh,their participation will increase substantially.This study aims to provide a more reasonable approach to solving multi-objective optimization problems.展开更多
In this paper,we develop an advanced computational framework for the topology optimization of orthotropic materials using meshless methods.The approximation function is established based on the improved moving least s...In this paper,we develop an advanced computational framework for the topology optimization of orthotropic materials using meshless methods.The approximation function is established based on the improved moving least squares(IMLS)method,which enhances the efficiency and stability of the numerical solution.The numerical solution formulas are derived using the improved element-free Galerkin(IEFG)method.We introduce the solid isotropic microstructures with penalization(SIMP)model to formulate a mathematical model for topology opti-mization,which effectively penalizes intermediate densities.The optimization problem is defined with the numerical solution formula and volume fraction as constraints.The objective function,which is the minimum value of flexibility,is optimized iteratively using the optimization criterion method to update the design variables efficiently and converge to an optimal solution.Sensitivity analysis is performed using the adjoint method,which provides accurate and efficient gradient information for the optimization algorithm.We validate the proposed framework through a series of numerical examples,including clamped beam,cantilever beam,and simply supported beam made of orthotropic materials.The convergence of the objective function is demonstrated by increasing the number of iterations.Additionally,the stability of the iterative process is analyzed by examining the fluctuation law of the volume fraction.By adjusting the parameters to an appropriate range,we achieve the final optimization results of the IEFG method without the checkerboard phenomenon.Comparative studies between the Element-Free Galerkin(EFG)and IEFG methods reveal that both methods yield consistent optimization results under identical parameter settings.However,the IEFG method significantly reduces computational time,highlighting its efficiency and suitability for orthotropic materials.展开更多
Understanding the wind power potential of a site is essential for designing an optimal wind power conditioning system. The Weibull distribution and wind speed extrapolation methods are powerful mathematical tools for ...Understanding the wind power potential of a site is essential for designing an optimal wind power conditioning system. The Weibull distribution and wind speed extrapolation methods are powerful mathematical tools for efficiently predicting the frequency distribution of wind speeds at a site. Hourly wind speed and direction data were collected from the National Aeronautics and Space Administration (NASA) website for the period 2013 to 2023. MATLAB software was used to calculate the distribution parameters using the graphical method and to plot the corresponding curves, while WRPLOTView software was used to construct the wind rose. The average wind speed obtained is 3.33 m/s and can reach up to 5.71 m/s at a height of 100 meters. The wind energy is estimated to be 1315.30 kWh/m2 at a height of 100 meters. The wind rose indicates the prevailing winds (ranging from 3.60 m/s to 5.70 m/s) in the northeast-east direction.展开更多
Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the structure.Therefore,it is particularly significant to identify the structural modal parameters accordi...Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the structure.Therefore,it is particularly significant to identify the structural modal parameters according to the monitoring data information in the structural health monitoring(SHM)system,so as to provide a scientific basis for structural damage identification and dynamic model modification.In view of this,this paper reviews methods for identifying structural modal parameters under environmental excitation and briefly describes how to identify structural damages based on the derived modal parameters.The paper primarily introduces data-driven modal parameter recognition methods(e.g.,time-domain,frequency-domain,and time-frequency-domain methods,etc.),briefly describes damage identification methods based on the variations of modal parameters(e.g.,natural frequency,modal shapes,and curvature modal shapes,etc.)and modal validation methods(e.g.,Stability Diagram and Modal Assurance Criterion,etc.).The current status of the application of artificial intelligence(AI)methods in the direction of modal parameter recognition and damage identification is further discussed.Based on the pre-vious analysis,the main development trends of structural modal parameter recognition and damage identification methods are given to provide scientific references for the optimized design and functional upgrading of SHM systems.展开更多
Objective:To evaluate the effectiveness and safety of Bushen Huoxue prescription in the treatment of recurrent spontaneous abortion(RSA)due to prethrombotic state(PTS).Methods:Databases such as CNKI,WanFang,VIP,CBM,Pu...Objective:To evaluate the effectiveness and safety of Bushen Huoxue prescription in the treatment of recurrent spontaneous abortion(RSA)due to prethrombotic state(PTS).Methods:Databases such as CNKI,WanFang,VIP,CBM,PubMed,Embase,and Cochrane Library were searched for randomized controlled trials on Bushen Huoxue prescription in treating RSA due to PTS from inception to March 2021;meta-analysis was performed by RevMan Version 5.3.0 following quality evaluation.Results:Seven trials were included,with 496 patients;the meta-analysis indicated that Bushen Huoxue prescription has advantages on the improvement of total clinical effective rate[RR=1.22,95%CI(1.10,1.35),Z=3.80(P=0.0001)],embryo survival rate at pregnancy of 12 weeks[RR=1.25,95%CI(1.10,1.41),Z=3.53(P=0.0004)],D-dimer levels[SMD=-1.59,95%CI(-2.20,-0.97),Z=5.07(P<0.00001)],and fibrinogen levels[MD=-1.00,95%CI(-1.29,-0.70),Z=6.61(P<0.00001)],but the statistical heterogeneity was significant;in terms of incidence of adverse reactions,there was no statistical difference between Bushen Huoxue prescription and western medicine.Conclusion:Compared with western medicine alone,Bushen Huoxue prescription alone or in combination with western medicine showed significant advantages in improving the overall clinical efficiency,embryonic survival rate at 12 weeks of pregnancy,and reducing D-dimer values as well as fibrinogen levels,without any significant difference in the incidence of adverse effects;however,the number of included studies is small and there are drawbacks,such as small sample size and low quality;therefore,high-quality clinical studies with large sample size and rigorous trial designs are needed in the future to provide a reliable basis for the effectiveness and safety of TCM in reducing the incidence of RSA due to prethrombotic state.展开更多
Due to the heterogeneity of rock masses and the variability of in situ stress,the traditional linear inversion method is insufficiently accurate to achieve high accuracy of the in situ stress field.To address this cha...Due to the heterogeneity of rock masses and the variability of in situ stress,the traditional linear inversion method is insufficiently accurate to achieve high accuracy of the in situ stress field.To address this challenge,nonlinear stress boundaries for a numerical model are determined through regression analysis of a series of nonlinear coefficient matrices,which are derived from the bubbling method.Considering the randomness and flexibility of the bubbling method,a parametric study is conducted to determine recommended ranges for these parameters,including the standard deviation(σb)of bubble radii,the non-uniform coefficient matrix number(λ)for nonlinear stress boundaries,and the number(m)and positions of in situ stress measurement points.A model case study provides a reference for the selection of these parameters.Additionally,when the nonlinear in situ stress inversion method is employed,stress distortion inevitably occurs near model boundaries,aligning with the Saint Venant's principle.Two strategies are proposed accordingly:employing a systematic reduction of nonlinear coefficients to achieve high inversion accuracy while minimizing significant stress distortion,and excluding regions with severe stress distortion near the model edges while utilizing the central part of the model for subsequent simulations.These two strategies have been successfully implemented in the nonlinear in situ stress inversion of the Xincheng Gold Mine and have achieved higher inversion accuracy than the linear method.Specifically,the linear and nonlinear inversion methods yield root mean square errors(RMSE)of 4.15 and 3.2,and inversion relative errors(δAve)of 22.08%and 17.55%,respectively.Therefore,the nonlinear inversion method outperforms the traditional multiple linear regression method,even in the presence of a systematic reduction in the nonlinear stress boundaries.展开更多
Shock wave caused by a sudden release of high-energy,such as explosion and blast,usually affects a significant range of areas.The utilization of a uniform fine mesh to capture sharp shock wave and to obtain precise re...Shock wave caused by a sudden release of high-energy,such as explosion and blast,usually affects a significant range of areas.The utilization of a uniform fine mesh to capture sharp shock wave and to obtain precise results is inefficient in terms of computational resource.This is particularly evident when large-scale fluid field simulations are conducted with significant differences in computational domain size.In this work,a variable-domain-size adaptive mesh enlargement(vAME)method is developed based on the proposed adaptive mesh enlargement(AME)method for modeling multi-explosives explosion problems.The vAME method reduces the division of numerous empty areas or unnecessary computational domains by adaptively suspending enlargement operation in one or two directions,rather than in all directions as in AME method.A series of numerical tests via AME and vAME with varying nonintegral enlargement ratios and different mesh numbers are simulated to verify the efficiency and order of accuracy.An estimate of speedup ratio is analyzed for further efficiency comparison.Several large-scale near-ground explosion experiments with single/multiple explosives are performed to analyze the shock wave superposition formed by the incident wave,reflected wave,and Mach wave.Additionally,the vAME method is employed to validate the accuracy,as well as to investigate the performance of the fluid field and shock wave propagation,considering explosive quantities ranging from 1 to 5 while maintaining a constant total mass.The results show a satisfactory correlation between the overpressure versus time curves for experiments and numerical simulations.The vAME method yields a competitive efficiency,increasing the computational speed to 3.0 and approximately 120,000 times in comparison to AME and the fully fine mesh method,respectively.It indicates that the vAME method reduces the computational cost with minimal impact on the results for such large-scale high-energy release problems with significant differences in computational domain size.展开更多
The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained expe...The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained experimentally through tests on specimens under multiaxial loading with that calculated by the variance method. In the statistical approach criteria, several methods have been developed but we have presented only one method, namely the variance method using the equivalent stress. She assumes that the fracture plane orientation is the one on which the variance of the equivalent stress is maximum. Three types of equivalent stress are defined for this method [1]: normal stress, shear stress and combined normal and shear stress. The results obtained were compared with experimental results for multiaxial cyclic stress states, and it emerges that the variance method for the case of combined loading is conservative as it gives a better prediction of the fracture plane.展开更多
To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based sim...To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based simulation(NNS)method with higher accuracy and better efficiency was proposed.The NNS method consisted of three main steps.First,the parameters of blast loads,including the peak pressures and impulses of cylindrical charges with different aspect ratios(L/D)at different stand-off distances and incident angles were obtained by two-dimensional numerical simulations.Subsequently,incident shape factors of cylindrical charges with arbitrary aspect ratios were predicted by a neural network.Finally,reflected shape factors were derived and implemented into the subroutine of the ABAQUS code to modify the CONWEP model,including modifications of impulse and overpressure.The reliability of the proposed NNS method was verified by related experimental results.Remarkable accuracy improvement was acquired by the proposed NNS method compared with the unmodified CONWEP model.Moreover,huge efficiency superiority was obtained by the proposed NNS method compared with the CEL method.The proposed NNS method showed good accuracy when the scaled distance was greater than 0.2 m/kg^(1/3).It should be noted that there is no need to generate a new dataset again since the blast loads satisfy the similarity law,and the proposed NNS method can be directly used to simulate the blast loads generated by different cylindrical charges.The proposed NNS method with high efficiency and accuracy can be used as an effective method to analyze the dynamic response of structures under blast loads,and it has significant application prospects in designing protective structures.展开更多
[Objectives]To make a systematic evaluation on the therapeutic efficacy of purgation and catharsis method combined with western medicine in treatment of severe pneumonia.[Methods]The literatures were retrieved from Ch...[Objectives]To make a systematic evaluation on the therapeutic efficacy of purgation and catharsis method combined with western medicine in treatment of severe pneumonia.[Methods]The literatures were retrieved from China Knowledge Infrastructure(CNKI),Chinese science and technology journal full-text database(VIP database,VIP),Wanfang Data,the Chinese biomedical database,PubMed,Embase,and the Cochrane Library.The retrieval time was set to the period from the creation of the database to June 2020.The randomized controlled trial(RCT)was conducted on the comparison between the purgation and catharsis method combined with western medicine and the western medicine alone in the treatment of severe pneumonia.The literature information was extracted and the methodological quality of the included literature was evaluated according to the bias risk assessment tool developed by the Cochrane Collaboration.Meta-analysis was performed with the aid of RevMan 5.3 software for the patient response rate,acute physiology and chronic health evaluations II(APACHE II),clinical pulmonary infection score(CPIS),oxygenation index(OI),procalcitonin(PCT),mechanical ventilation time,etc.[Results]A total of 20 articles were included,involving a total of 1661 patients,and the literature quality was low.Meta analysis results showed that compared with the treatment by western medicine alone,the purgation and catharsis method combined with western medicine can further improve the response rate[RR=1.21,95%CI(1.14,1.27),P<0.00001],and reduce the APACHE II score[WMD=-5.92,95%CI(-7.94,-3.89),P<0.00001],reduce CPIS score[WMD=-1.41,95%CI(-1.70,-1.12),P<0.00001],increase oxygenation index[WMD=39.52,95%CI(29.39,49.65),P<0.00001],reduce PCT level[WMD=-2.85,95%CI(-3.68,-2.01),P<0.00001],shorten the mechanical ventilation time[WMD=-13.00,95%CI(-16.51,-9.48),P<0.00001].[Conclusions]Within the scope of the study included,the purgation and catharsis method combined with western medicine in the treatment of severe pneumonia can further reduce the pulmonary infection,reduce PCT levels,increase oxygenation index,and improve vital organ functions,thereby improving clinical efficacy,shortening the mechanical ventilation time(MVT),and reducing the economic burden of patients.展开更多
The identification of the traction acting on a portion of the surface of an anisotropic solid is very important in structural health monitoring and optimal design of structures. The traction can be determined using in...The identification of the traction acting on a portion of the surface of an anisotropic solid is very important in structural health monitoring and optimal design of structures. The traction can be determined using inverse methods in which displacement or strain measurements are taken at several points on the body. This paper presents an inverse method based on the method of fundamental solutions for the traction identification problem in two-dimensional anisotropic elasticity. The method of fundamental solutions is an efficient boundary-type meshless method widely used for analyzing various problems. Since the problem is linear, the sensitivity analysis is simply performed by solving the corresponding direct problem several times with different loads. The effects of important parameters such as the number of measurement data, the position of the measurement points, the amount of measurement error, and the type of measurement, i.e., displacement or strain, on the results are also investigated. The results obtained show that the presented inverse method is suitable for the problem of traction identification. It can be concluded from the results that the use of strain measurements in the inverse analysis leads to more accurate results than the use of displacement measurements. It is also found that measurement points closer to the boundary with unknown traction provide more reliable solutions. Additionally, it is found that increasing the number of measurement points increases the accuracy of the inverse solution. However, in cases with a large number of measurement points, further increasing the number of measurement data has little effect on the results.展开更多
文摘AIM: To compare the functional outcomes of patients who underwent open surgery vs Ponseti method for the management of idiopathic clubfoot and to determine whether correlations exist between functional outcome and radiographic measurements.METHODS: A meta-analysis of the literature was conducted for studies concerning primary treatment of patients with idiopathic clubfoot. We searched PubM ed Medline, EMBASE, and the Cochrane Library databases from January 1950 to October 2011. Meta-analyses were performed on outcomes from 12 studies. Pooled means, SDs, and sample sizes were either identified in the results or calculated based on the results of each study.RESULTS: Overall, 835 treated idiopathic clubfeet in 516 patients were reviewed. The average follow-up was 15.7 years. Patients managed with Ponseti method did have a higher rate of excellent or good outcome than patients treated with open surgery(0.76 and 0.62, respectively), but not quite to the point of statistical significance(Q = 3.73, P = 0.053). Age at surgery wasnot correlated with the functional outcome for the surgically treated patients(r =-0.32, P = 0.68). A larger anteroposterior talocalcaneal angle was correlated with a higher rate of excellent or good outcomes(r = 0.80, P = 0.006). There were no other significant correlations between the functional and radiographic outcomes.CONCLUSION: The Ponseti method should be considered the initial treatment of idiopathic clubfeet, and open surgery should be reserved for clubfeet that cannot be completely corrected.
基金financially supported by the CAS consultation project“South China Sea Oil and Gas Comprehensive Development Strategy”(2019-ZW11-Z-035)the National Basic Research Program of China(973 Program)(2006CB202300,2011CB201100)the National High-Tech R&D Program of China(863 Program)(2013AA092600)。
文摘Natural gas hydrate(NGH),considered as a type of premium energy alternative to conventional hydrocarbons,has been broadly studied.The estimate of the total NGH resources in the world has decreased by more than 90%since the first evaluation in 1973.Geographic and geophysical conditions of the South China Sea(SCS)are favorable for the formation of NGH,which has been proved by drilling results up to date.The recoverability of the NGH in the SCS has been confirmed by the production tests using both vertical and horizontal wells.Since 2001,35 estimates of NGH resources in the SCS have been made,with relatively stable results varying between 600 and 900×109 ton oil equivalent.In these estimations,the volumetric method was commonly adopted,but the geological conditions,the migration-accumulation mechanisms of NGH,and the practical recoverability were not considered.These estimates cannot be regarded as evaluated resources according to the international resource evaluation standards,but are at most about prospective gas content of NGH,thus inefficient for guiding explorations and developments.To solve these problems,this study divides the past NGH surveys in the SCS into seven stages,acquires key geological parameters of every stage based on previous studies and analogy with other areas,evaluates the NGH resources of these seven stages by using the volumetric method,then adopts a new trend-analysis method to simulate the downward trend of these estimates,and finally predicts the NGH resources in the SCS at 2025 and 2030.The downward trend is because of the continuous improvement of NGH understanding over time,which is consistent with the trend of global NGH estimates.At the present stage(from 2019 to 2021),the average technically recoverable resource(ATRR)is 7.0×10^(12)m^(3),and the estimates of 2025 and 2030 ATRR are 6.46×10^(12)m^(3) and 4.01×10^(12)m^(3)respectively,with a difference of less than 40%.Therefore,it can be inferred that the ATRR of NGH in the SCS is between 4.0 and 6.5×10^(12)m^(3),with an average of 5.25×10^(12)m^(3).
基金supported by the Support Program(Ⅱ)of Hundreds of Universities Outstanding Innovative Talents in Hebei Province of China,No.BR2-104
文摘OBJECTIVE： To evaluate the effectiveness and safety of the Xingnao Kaiqiao needling method for treating acute ischemic stroke.DATA SOURCES： We retrieved relevant randomized controlled trials involving Xingnao Kaiqiao acupuncture for treatment of acute ischemic stroke. The China National Knowledge Infrastructure, Weipu Information Resources System, Wanfang Medical Data System, Chinese Biomedical Literature Database, Cochrane Library, and Pub Med were searched from June 2006 to March 2016.DATA SELECTION： We analyzed randomized and semi-randomized clinical controlled trials that compared Xingnao Kaiqiao acupuncture with various control treatments, such as conventional drugs or other acupuncture therapies, for treatment of acute ischemic stroke. The quality of articles was evaluated according to the Cochrane Handbook for Systematic Reviews of Interventions（Version 5.1）, and the study was carried out using Cochrane system assessment methods. Rev Man 5.2 was used for the meta-analysis of the included studies.OUTCOME MEASURES： The mortality rate, disability rate, activities of daily living（Barthel Index）, and clinical efficacy were observed.RESULTS： Twelve studies met the inclusion criteria for this review. The meta-analysis showed that between Xingnao Kaiqiao acupuncture and the control treatment, Xingnao Kaiqiao acupuncture reduced the disability rate [risk ratio（RR） = 0.51, 95% confidence interval（CI） = 0.27-0.98, z = 2.03, P 〈 0.05], elevated the activities of daily living（weighted mean difference = 12.23, 95% CI： 3.66-20.08, z = 2.80, P 〈 0.005）, and had greater clinical efficacy（RR = 1.61, 95% CI： 1.23-2.09, z = 3.53, P 〈 0.0004）. However, there was no significant difference in mortality rate（RR = 0.61, 95% CI： 0.15-2.45, z = 0.70, P 〉 0.05）. CONCLUSION： The Xingnao Kaiqiao needling method is effective and safe for acute ischemic stroke. However, there was selective bias in this study, and the likelihood of measurement bias is high. Thus, more high-quality randomized controlled trials are needed to provide reliable evidence of the efficacy and safety of Xingnao Kaiqiao acupuncture in the treatment of acute ischemic stroke.
文摘Objective:Skill competence is essential for nursing students and experiential teaching method has become increasingly popular in China’s nursing education.To systematically evaluate the effects of experiential teaching method on the development of nursing students’skill competence,and to provide evidence for nursing education.Methods:The China National Knowledge Infrastructure,VIP,Wanfang Data,PubMed,and Web of Science databases were searched from their inception until November 28,2019.We screened the studies according to inclusion and exclusion criteria,extracted the data,and assessed the quality.Then,a meta-analysis was conducted.Results:Totally 15 studies were included,and 1,633 nursing students were analyzed by Review Manager5.3 and Stata15.1 software.The results show that the experiential teaching method can significantly improve nursing students’nursing skills such as training(SMD=1.05,95%CI:0.95–1.16,P=0.000),learning interest(ES=0.93,95%CI:0.79–1.06),ability to analyze and solve problems(ES=0.75,95%CI:0.55–0.94),ability to judge and innovative thinking(ES=1.01,95%CI:0.77–1.25),abilities of understanding and perception(ES=0.59,95%CI:0.34–0.83),and teaching satisfaction(ES=1.26,95%CI:1.13–1.4).Conclusions:The results suggest that the experiential teaching method is more effective for the nursing students’skill competence than traditional teaching in China.However,due to the heterogeneity and bias risk,a large sample and high-quality studies are needed in future to confirm its effectiveness.
基金supported by the National Natural Science Foundation of China(12172023).
文摘The separation-of-variable(SOV)methods,such as the improved SOV method,the variational SOV method,and the extended SOV method,have been proposed by the present authors and coworkers to obtain the closed-form analytical solutions for free vibration and eigenbuckling of rectangular plates and circular cylindrical shells.By taking the free vibration of rectangular thin plates as an example,this work presents the theoretical framework of the SOV methods in an instructive way,and the bisection–based solution procedures for a group of nonlinear eigenvalue equations.Besides,the explicit equations of nodal lines of the SOV methods are presented,and the relations of nodal line patterns and frequency orders are investigated.It is concluded that the highly accurate SOV methods have the same accuracy for all frequencies,the mode shapes about repeated frequencies can also be precisely captured,and the SOV methods do not have the problem of missing roots as well.
基金The second round of construction project of the National Traditional Chinese Medicine School Inheritance Studio of the State Administration of Traditional Chinese Medicine(Guo TCM Ren Jiao Han[2019]No.62)Scientific Research Project of the Shaanxi Provincial Administration of Traditional Chinese Medicine(No.2019-ZZ-LC006)Shaanxi The construction project of famous traditional Chinese medicine inheritance studio of Provincial Administration of Traditional Chinese Medicine(No.2019017).
文摘Objective:This article uses a meta-analysis system to evaluate the clinical efficacy of the method of spleen-invigorating,kidney-tonifying and blood-activating combined with western medicine in the treatment of diabetic nephropathy,in order to provide evidence-based medicine for the clinical treatment of this disease.Methods:Computer search(January 2009 to June 2020)published in CNKI,Wanfang database,and Weipu Chinese Science and Technology Journal Database with simple western medicine conventional treatment(control group)and on the basis of control group Randomized Controlled Trial(RCT)of the treatment of diabetic nephropathy with spleen-invigorating,kidney-tonifying and blood-activating(experimental group),and manual retrieval of relevant literature that meets the inclusion criteria.Two researchers independently carried out literature screening,and used the improved Jadad rating scale for quality evaluation,and finally used RevMan5.3 statistical software for meta-analysis.Results:A total of 15 randomized controlled trials were included,with a total of 1218 patients,including 621 in the experimental group and 597 in the control group.Meta-analysis showed that the experimental group was improving clinical efficacy(OR=4.35,95%CI[3.12,6.08],P<0.00001),FPG(MD=-0.49,95%CI[-0.89,-0.09],P=0.02),24h urine protein quantification(MD=-0.54,95%CI[-0.90,-0.18],P=0.003),mALB(MD=-15.95,95%CI[-18.12,-13.79],P<0.0001),BUN(MD=-1.79,95%CI[-2.99,-0.59],P=0.004),SCr(MD=-47.63,95%CI[-83.43,-11.83],P=0.009),TC(MD=-1.02,95%CI[-1.42,-0.62],P<0.00001),etc.may be better than the control group;The test group is improving TG(MD=-1.02,95%CI[-1.42,-0.62],P<0.00001)there is no significant difference compared with the control group.Conclusion:The method of spleen-invigorating,kidney-tonifying and blood-activating combined with conventional western medicine treatment of diabetic nephropathy may be superior to conventional western medicine treatment in terms of improving clinical efficacy,FPG,24h urine protein quantification,mALB,BUN,SCr,TC,etc.However,due to the small number and low quality of the literature included in this study,more in-depth research needs to further expand the sample size and include higher quality RCTs.
基金Funded by the Natural Science Foundation of Jiangsu Province(No.BK20241529)China Postdoctoral Science Foundation(No.2024M750736)。
文摘This study aims to develop a chloride diffusion simulation method that considers the hydration microstructure and pore solution properties during the hydration of tricalcium silicate(C3S).The method combines the hydration simulation,thermodynamic calculation,and finite element analysis to examine the effects of pore solution,including effect of electrochemical potential,effect of chemical activity,and effect of mechanical interactions between ions,on the chloride effective diffusion coefficient of hydrated C3S paste.The results indicate that the effect of electrochemical potential on chloride diffusion becomes stronger with increasing hydration age due to the increase in the content of hydrated calcium silicate;as the hydration age increases,the effect of chemical activity on chloride diffusion weakens when the number of diffusible elements decreases;the effect of mechanical interactions between ions on chloride diffusion decreases with the increase of hydration age.
基金funded by the project of the Major Scientific and Technological Projects of CNOOC in the 14th Five-Year Plan(No.KJGG2022-0701)the CNOOC Research Institute(No.2020PFS-03).
文摘To analyze the differences in the transport and distribution of different types of proppants and to address issues such as the short effective support of proppant and poor placement in hydraulically intersecting fractures,this study considered the combined impact of geological-engineering factors on conductivity.Using reservoir production parameters and the discrete elementmethod,multispherical proppants were constructed.Additionally,a 3D fracture model,based on the specified conditions of the L block,employed coupled(Computational Fluid Dynamics)CFD-DEM(Discrete ElementMethod)for joint simulations to quantitatively analyze the transport and placement patterns of multispherical proppants in intersecting fractures.Results indicate that turbulent kinetic energy is an intrinsic factor affecting proppant transport.Moreover,the efficiency of placement and migration distance of low-sphericity quartz sand constructed by the DEM in the main fracture are significantly reduced compared to spherical ceramic proppants,with a 27.7%decrease in the volume fraction of the fracture surface,subsequently affecting the placement concentration and damaging fracture conductivity.Compared to small-angle fractures,controlling artificial and natural fractures to expand at angles of 45°to 60°increases the effective support length by approximately 20.6%.During hydraulic fracturing of gas wells,ensuring the fracture support area and post-closure conductivity can be achieved by controlling the sphericity of proppants and adjusting the perforation direction to control the direction of artificial fractures.
基金sponsored by R&D Program of Beijing Municipal Education Commission(KM202410009013).
文摘In the independent electro-hydrogen system(IEHS)with hybrid energy storage(HESS),achieving optimal scheduling is crucial.Still,it presents a challenge due to the significant deviations in values ofmultiple optimization objective functions caused by their physical dimensions.These deviations seriously affect the scheduling process.A novel standardization fusion method has been established to address this issue by analyzing the variation process of each objective function’s values.The optimal scheduling results of IEHS with HESS indicate that the economy and overall energy loss can be improved 2–3 times under different optimization methods.The proposed method better balances all optimization objective functions and reduces the impact of their dimensionality.When the cost of BESS decreases by approximately 30%,its participation deepens by about 1 time.Moreover,if the price of the electrolyzer is less than 15¥/kWh or if the cost of the fuel cell drops below 4¥/kWh,their participation will increase substantially.This study aims to provide a more reasonable approach to solving multi-objective optimization problems.
基金supported by the Graduate Student Scientific Research Innovation Project through Research Innovation Fund for Graduate Students in Shanxi Province(Project No.2024KY648).
文摘In this paper,we develop an advanced computational framework for the topology optimization of orthotropic materials using meshless methods.The approximation function is established based on the improved moving least squares(IMLS)method,which enhances the efficiency and stability of the numerical solution.The numerical solution formulas are derived using the improved element-free Galerkin(IEFG)method.We introduce the solid isotropic microstructures with penalization(SIMP)model to formulate a mathematical model for topology opti-mization,which effectively penalizes intermediate densities.The optimization problem is defined with the numerical solution formula and volume fraction as constraints.The objective function,which is the minimum value of flexibility,is optimized iteratively using the optimization criterion method to update the design variables efficiently and converge to an optimal solution.Sensitivity analysis is performed using the adjoint method,which provides accurate and efficient gradient information for the optimization algorithm.We validate the proposed framework through a series of numerical examples,including clamped beam,cantilever beam,and simply supported beam made of orthotropic materials.The convergence of the objective function is demonstrated by increasing the number of iterations.Additionally,the stability of the iterative process is analyzed by examining the fluctuation law of the volume fraction.By adjusting the parameters to an appropriate range,we achieve the final optimization results of the IEFG method without the checkerboard phenomenon.Comparative studies between the Element-Free Galerkin(EFG)and IEFG methods reveal that both methods yield consistent optimization results under identical parameter settings.However,the IEFG method significantly reduces computational time,highlighting its efficiency and suitability for orthotropic materials.
文摘Understanding the wind power potential of a site is essential for designing an optimal wind power conditioning system. The Weibull distribution and wind speed extrapolation methods are powerful mathematical tools for efficiently predicting the frequency distribution of wind speeds at a site. Hourly wind speed and direction data were collected from the National Aeronautics and Space Administration (NASA) website for the period 2013 to 2023. MATLAB software was used to calculate the distribution parameters using the graphical method and to plot the corresponding curves, while WRPLOTView software was used to construct the wind rose. The average wind speed obtained is 3.33 m/s and can reach up to 5.71 m/s at a height of 100 meters. The wind energy is estimated to be 1315.30 kWh/m2 at a height of 100 meters. The wind rose indicates the prevailing winds (ranging from 3.60 m/s to 5.70 m/s) in the northeast-east direction.
基金supported by the Innovation Foundation of Provincial Education Department of Gansu(2024B-005)the Gansu Province National Science Foundation(22YF7GA182)the Fundamental Research Funds for the Central Universities(No.lzujbky2022-kb01)。
文摘Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the structure.Therefore,it is particularly significant to identify the structural modal parameters according to the monitoring data information in the structural health monitoring(SHM)system,so as to provide a scientific basis for structural damage identification and dynamic model modification.In view of this,this paper reviews methods for identifying structural modal parameters under environmental excitation and briefly describes how to identify structural damages based on the derived modal parameters.The paper primarily introduces data-driven modal parameter recognition methods(e.g.,time-domain,frequency-domain,and time-frequency-domain methods,etc.),briefly describes damage identification methods based on the variations of modal parameters(e.g.,natural frequency,modal shapes,and curvature modal shapes,etc.)and modal validation methods(e.g.,Stability Diagram and Modal Assurance Criterion,etc.).The current status of the application of artificial intelligence(AI)methods in the direction of modal parameter recognition and damage identification is further discussed.Based on the pre-vious analysis,the main development trends of structural modal parameter recognition and damage identification methods are given to provide scientific references for the optimized design and functional upgrading of SHM systems.
基金National Natural Science Foundation of China Project(Project Number:81603656)Shaanxi University of Traditional Chinese Medicine 2017 Annual Scientific Research Program Project(Project Number:2017PY10)Infertility Innovation Team(Project Number:132041929).
文摘Objective:To evaluate the effectiveness and safety of Bushen Huoxue prescription in the treatment of recurrent spontaneous abortion(RSA)due to prethrombotic state(PTS).Methods:Databases such as CNKI,WanFang,VIP,CBM,PubMed,Embase,and Cochrane Library were searched for randomized controlled trials on Bushen Huoxue prescription in treating RSA due to PTS from inception to March 2021;meta-analysis was performed by RevMan Version 5.3.0 following quality evaluation.Results:Seven trials were included,with 496 patients;the meta-analysis indicated that Bushen Huoxue prescription has advantages on the improvement of total clinical effective rate[RR=1.22,95%CI(1.10,1.35),Z=3.80(P=0.0001)],embryo survival rate at pregnancy of 12 weeks[RR=1.25,95%CI(1.10,1.41),Z=3.53(P=0.0004)],D-dimer levels[SMD=-1.59,95%CI(-2.20,-0.97),Z=5.07(P<0.00001)],and fibrinogen levels[MD=-1.00,95%CI(-1.29,-0.70),Z=6.61(P<0.00001)],but the statistical heterogeneity was significant;in terms of incidence of adverse reactions,there was no statistical difference between Bushen Huoxue prescription and western medicine.Conclusion:Compared with western medicine alone,Bushen Huoxue prescription alone or in combination with western medicine showed significant advantages in improving the overall clinical efficiency,embryonic survival rate at 12 weeks of pregnancy,and reducing D-dimer values as well as fibrinogen levels,without any significant difference in the incidence of adverse effects;however,the number of included studies is small and there are drawbacks,such as small sample size and low quality;therefore,high-quality clinical studies with large sample size and rigorous trial designs are needed in the future to provide a reliable basis for the effectiveness and safety of TCM in reducing the incidence of RSA due to prethrombotic state.
基金funded by the National Key R&D Program of China(Grant No.2022YFC2903904)the National Natural Science Foundation of China(Grant Nos.51904057 and U1906208).
文摘Due to the heterogeneity of rock masses and the variability of in situ stress,the traditional linear inversion method is insufficiently accurate to achieve high accuracy of the in situ stress field.To address this challenge,nonlinear stress boundaries for a numerical model are determined through regression analysis of a series of nonlinear coefficient matrices,which are derived from the bubbling method.Considering the randomness and flexibility of the bubbling method,a parametric study is conducted to determine recommended ranges for these parameters,including the standard deviation(σb)of bubble radii,the non-uniform coefficient matrix number(λ)for nonlinear stress boundaries,and the number(m)and positions of in situ stress measurement points.A model case study provides a reference for the selection of these parameters.Additionally,when the nonlinear in situ stress inversion method is employed,stress distortion inevitably occurs near model boundaries,aligning with the Saint Venant's principle.Two strategies are proposed accordingly:employing a systematic reduction of nonlinear coefficients to achieve high inversion accuracy while minimizing significant stress distortion,and excluding regions with severe stress distortion near the model edges while utilizing the central part of the model for subsequent simulations.These two strategies have been successfully implemented in the nonlinear in situ stress inversion of the Xincheng Gold Mine and have achieved higher inversion accuracy than the linear method.Specifically,the linear and nonlinear inversion methods yield root mean square errors(RMSE)of 4.15 and 3.2,and inversion relative errors(δAve)of 22.08%and 17.55%,respectively.Therefore,the nonlinear inversion method outperforms the traditional multiple linear regression method,even in the presence of a systematic reduction in the nonlinear stress boundaries.
基金supported by the National Natural Science Foundation of China(Grant Nos.12302435 and 12221002)。
文摘Shock wave caused by a sudden release of high-energy,such as explosion and blast,usually affects a significant range of areas.The utilization of a uniform fine mesh to capture sharp shock wave and to obtain precise results is inefficient in terms of computational resource.This is particularly evident when large-scale fluid field simulations are conducted with significant differences in computational domain size.In this work,a variable-domain-size adaptive mesh enlargement(vAME)method is developed based on the proposed adaptive mesh enlargement(AME)method for modeling multi-explosives explosion problems.The vAME method reduces the division of numerous empty areas or unnecessary computational domains by adaptively suspending enlargement operation in one or two directions,rather than in all directions as in AME method.A series of numerical tests via AME and vAME with varying nonintegral enlargement ratios and different mesh numbers are simulated to verify the efficiency and order of accuracy.An estimate of speedup ratio is analyzed for further efficiency comparison.Several large-scale near-ground explosion experiments with single/multiple explosives are performed to analyze the shock wave superposition formed by the incident wave,reflected wave,and Mach wave.Additionally,the vAME method is employed to validate the accuracy,as well as to investigate the performance of the fluid field and shock wave propagation,considering explosive quantities ranging from 1 to 5 while maintaining a constant total mass.The results show a satisfactory correlation between the overpressure versus time curves for experiments and numerical simulations.The vAME method yields a competitive efficiency,increasing the computational speed to 3.0 and approximately 120,000 times in comparison to AME and the fully fine mesh method,respectively.It indicates that the vAME method reduces the computational cost with minimal impact on the results for such large-scale high-energy release problems with significant differences in computational domain size.
文摘The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained experimentally through tests on specimens under multiaxial loading with that calculated by the variance method. In the statistical approach criteria, several methods have been developed but we have presented only one method, namely the variance method using the equivalent stress. She assumes that the fracture plane orientation is the one on which the variance of the equivalent stress is maximum. Three types of equivalent stress are defined for this method [1]: normal stress, shear stress and combined normal and shear stress. The results obtained were compared with experimental results for multiaxial cyclic stress states, and it emerges that the variance method for the case of combined loading is conservative as it gives a better prediction of the fracture plane.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52271317 and 52071149)the Fundamental Research Funds for the Central Universities(HUST:2019kfy XJJS007)。
文摘To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based simulation(NNS)method with higher accuracy and better efficiency was proposed.The NNS method consisted of three main steps.First,the parameters of blast loads,including the peak pressures and impulses of cylindrical charges with different aspect ratios(L/D)at different stand-off distances and incident angles were obtained by two-dimensional numerical simulations.Subsequently,incident shape factors of cylindrical charges with arbitrary aspect ratios were predicted by a neural network.Finally,reflected shape factors were derived and implemented into the subroutine of the ABAQUS code to modify the CONWEP model,including modifications of impulse and overpressure.The reliability of the proposed NNS method was verified by related experimental results.Remarkable accuracy improvement was acquired by the proposed NNS method compared with the unmodified CONWEP model.Moreover,huge efficiency superiority was obtained by the proposed NNS method compared with the CEL method.The proposed NNS method showed good accuracy when the scaled distance was greater than 0.2 m/kg^(1/3).It should be noted that there is no need to generate a new dataset again since the blast loads satisfy the similarity law,and the proposed NNS method can be directly used to simulate the blast loads generated by different cylindrical charges.The proposed NNS method with high efficiency and accuracy can be used as an effective method to analyze the dynamic response of structures under blast loads,and it has significant application prospects in designing protective structures.
基金Nanchong City R&D Funding Project(19YFZJ0005):Clinical Study on the Efficacy and Safety Evaluation of Catharsis,Stasis Elimination and Perfusion Method in Treating Severe Patients with Gastrointestinal DysfunctionProject of Famous Old Chinese Physicians Case Research Center of Nanchong City(YAZX19-Y-07):Study on Chief Physician Xu Shihong's Clinical Experience and Academic Thoughts of Syndrome Differentiation in the Treatment of COPD.
文摘[Objectives]To make a systematic evaluation on the therapeutic efficacy of purgation and catharsis method combined with western medicine in treatment of severe pneumonia.[Methods]The literatures were retrieved from China Knowledge Infrastructure(CNKI),Chinese science and technology journal full-text database(VIP database,VIP),Wanfang Data,the Chinese biomedical database,PubMed,Embase,and the Cochrane Library.The retrieval time was set to the period from the creation of the database to June 2020.The randomized controlled trial(RCT)was conducted on the comparison between the purgation and catharsis method combined with western medicine and the western medicine alone in the treatment of severe pneumonia.The literature information was extracted and the methodological quality of the included literature was evaluated according to the bias risk assessment tool developed by the Cochrane Collaboration.Meta-analysis was performed with the aid of RevMan 5.3 software for the patient response rate,acute physiology and chronic health evaluations II(APACHE II),clinical pulmonary infection score(CPIS),oxygenation index(OI),procalcitonin(PCT),mechanical ventilation time,etc.[Results]A total of 20 articles were included,involving a total of 1661 patients,and the literature quality was low.Meta analysis results showed that compared with the treatment by western medicine alone,the purgation and catharsis method combined with western medicine can further improve the response rate[RR=1.21,95%CI(1.14,1.27),P<0.00001],and reduce the APACHE II score[WMD=-5.92,95%CI(-7.94,-3.89),P<0.00001],reduce CPIS score[WMD=-1.41,95%CI(-1.70,-1.12),P<0.00001],increase oxygenation index[WMD=39.52,95%CI(29.39,49.65),P<0.00001],reduce PCT level[WMD=-2.85,95%CI(-3.68,-2.01),P<0.00001],shorten the mechanical ventilation time[WMD=-13.00,95%CI(-16.51,-9.48),P<0.00001].[Conclusions]Within the scope of the study included,the purgation and catharsis method combined with western medicine in the treatment of severe pneumonia can further reduce the pulmonary infection,reduce PCT levels,increase oxygenation index,and improve vital organ functions,thereby improving clinical efficacy,shortening the mechanical ventilation time(MVT),and reducing the economic burden of patients.
基金funded by Vice Chancellor of Research at Shiraz University(grant 3GFU2M1820).
文摘The identification of the traction acting on a portion of the surface of an anisotropic solid is very important in structural health monitoring and optimal design of structures. The traction can be determined using inverse methods in which displacement or strain measurements are taken at several points on the body. This paper presents an inverse method based on the method of fundamental solutions for the traction identification problem in two-dimensional anisotropic elasticity. The method of fundamental solutions is an efficient boundary-type meshless method widely used for analyzing various problems. Since the problem is linear, the sensitivity analysis is simply performed by solving the corresponding direct problem several times with different loads. The effects of important parameters such as the number of measurement data, the position of the measurement points, the amount of measurement error, and the type of measurement, i.e., displacement or strain, on the results are also investigated. The results obtained show that the presented inverse method is suitable for the problem of traction identification. It can be concluded from the results that the use of strain measurements in the inverse analysis leads to more accurate results than the use of displacement measurements. It is also found that measurement points closer to the boundary with unknown traction provide more reliable solutions. Additionally, it is found that increasing the number of measurement points increases the accuracy of the inverse solution. However, in cases with a large number of measurement points, further increasing the number of measurement data has little effect on the results.
