Analyses of the effects of some parameters were performed to determine the admittance functions in a common two-compartment building with background porosity by the imposed excitation method.Variations of the magnific...Analyses of the effects of some parameters were performed to determine the admittance functions in a common two-compartment building with background porosity by the imposed excitation method.Variations of the magnification factors of fluctuating internal pressures were analyzed using 96 model cases under random fluctuating external pressure,and then corresponding design equations were fitted.The results show that the Helmholtz resonance peaks of the admittance functions in both compartments increase with increasing the area of windward or partition wall opening.With increasing the volume of the compartment with an external opening,the resonance peak in this compartment at the higher Helmholtz frequency significantly decreases,at the same time,the resonance peak in the other compartment at the lower Helmholtz frequency also decreases.With increasing the volume of the compartment with background porosity,both resonance peaks in this compartment at the lower and higher Helmholtz frequencies decrease,meanwhile,the resonance peak at the lower Helmholtz frequency for the other compartment also decreases,whereas the resonance peak at the higher Helmholtz frequency increases.Both resonance peaks of the admittance functions in the two compartments decrease with increasing the amplitude of fluctuating external pressure coefficients or reference wind speed.展开更多
The successful confinement of the arc by the flux band depends on the welding process parameters for achieving single-pass,multi-layer, and ultra-narrow gap welding. The sidewall fusion depth, the width of the heat-af...The successful confinement of the arc by the flux band depends on the welding process parameters for achieving single-pass,multi-layer, and ultra-narrow gap welding. The sidewall fusion depth, the width of the heat-affected zone, and the line energy are utilized as comprehensive indications of the quality of the welded joint. In order to achieve well fusion and reduce the heat input to the base metal.Three welding process characteristics were chosen as the primary determinants, including welding voltage, welding speed, and wire feeding speed. The metamodel of the welding quality index was built by the orthogonal experiments. The metamodel and NSGA-Ⅱ(Non-dominated sorting genetic algorithm Ⅱ) were combined to develop a multi-objective optimization model of ultra-narrow gap welding process parameters. The results showed that the optimized welding process parameters can increase the sidewall fusion depth, reduce the width of the heataffected zone and the line energy, and to some extent improve the overall quality of the ultra-narrow gap welding process.展开更多
In this paper a mixed finite element method for the convection dominated diffusion problems with small parameter ε is presented,the effect of the parameter ε on the approximation error is considered and a su...In this paper a mixed finite element method for the convection dominated diffusion problems with small parameter ε is presented,the effect of the parameter ε on the approximation error is considered and a sufficient condition for optimal error estimates is derived.The paper also shows that under some conditions,the standard finite element method only gives a bounded solution,however the mixed finite element method gives a convergent one. Received March 1,1997. 1991 MR Subject Classification: 65N30,65M15.展开更多
Objective:To investigate the correlation of variables between dominant and non-dominant eyes in healthy young people.Methods:300 cases(600 eyes)of healthy young volunteers recruited in our hospital from March 2020 to ...Objective:To investigate the correlation of variables between dominant and non-dominant eyes in healthy young people.Methods:300 cases(600 eyes)of healthy young volunteers recruited in our hospital from March 2020 to February 2022were selected as the research objects.The general data of the volunteers were collected and the dominant eye,diopter,biological parameters and retinal blood flow density were detected.We compared all the test indexes of volunteers with different dominant eyes,and compared the refractive parameters,biological parameters and retinal blood flow density between the dominant and non-dominant eyes of volunteers.Results:Among the 300volunteers,62.67%(188/300)had the right eye as the dominant eye and 37.33%(112/300)had the left eye as the dominant eye.There was no significant difference in gender,BMI and equivalent spherical lens(SE)among the subjects with different dominant eyes(P>0.05).The SE and spherical diopter(S)of dominant eye were higher than that of non-dominant eye(P<0.05),but there was no significant difference between the dominant and non-dominant eye(C)(P>0.05);There was no significant difference in SE and C between dominant and non-dominant eye in volunteers with SE difference≤0.5 D and 0.51-1.25 D(P>0.05),and spherical diopter(S)of dominant eye was higher than that of non-dominant eye(P<0.05);The difference of SE was 1.26-2.00 D,>2.00 D,the SE and spherical diopter(S)of dominant eye were higher than those of non-dominant eye(P<0.05),but there was no significant difference between the dominant and non-dominant eye C(P>0.05).The levels of RA and CA in the dominant eye of 300 volunteers were lower than those in the non-dominant eye.The RA and CA levels of the dominant eye were lower than those of the non-dominant eye in volunteers with RA difference≤0.50 D,0.51-1.25 D,1.26-2.00 D,>2.00 D(P<0.05).There was no significant difference in the levels of axial length(AL),central corneal thickness(CCT),anterior chamber depth(ACD)and lens thickness(LT)between the dominant and non-dominant eyes(P>0.05).The levels of superficial retinal capillary layer(SVC),deep retinal capillary layer(DVC)and mean retinal blood flow density(RET)in dominant eyes were lower than those in non-dominant eyes.The level of AC in non-dominant eyes was higher than that in non-dominant eyes(P<0.05).Conclusion:The dominant eye of healthy young people is mostly the right eye,which has nothing to do with gender,age and BMI.Meanwhile,the biological parameters between the dominant and non-dominant eye were basically the same,the mean retinal blood flow density of the dominant eye was lower than that of the non-dominant eye,but its AC was higher than that of the non-dominant eye.展开更多
This paper is motivated by the concept of the signed k-domination problem and dedicated to the complexity of the problem on graphs. For any fixed nonnegative integer k, we show that the signed k-domination problem is ...This paper is motivated by the concept of the signed k-domination problem and dedicated to the complexity of the problem on graphs. For any fixed nonnegative integer k, we show that the signed k-domination problem is NP-complete for doubly chordal graphs. For strongly chordal graphs and distance-hereditary graphs, we show that the signed k-domination problem can be solved in polynomial time. We also show that the problem is linear-time solvable for trees, interval graphs, and chordal comparability graphs.展开更多
基金Projects(51278367,50878159)supported by the National Natural Science Foundation of ChinaProject(90715040)supported by the Major Research Program of National Natural Science Foundation of China
文摘Analyses of the effects of some parameters were performed to determine the admittance functions in a common two-compartment building with background porosity by the imposed excitation method.Variations of the magnification factors of fluctuating internal pressures were analyzed using 96 model cases under random fluctuating external pressure,and then corresponding design equations were fitted.The results show that the Helmholtz resonance peaks of the admittance functions in both compartments increase with increasing the area of windward or partition wall opening.With increasing the volume of the compartment with an external opening,the resonance peak in this compartment at the higher Helmholtz frequency significantly decreases,at the same time,the resonance peak in the other compartment at the lower Helmholtz frequency also decreases.With increasing the volume of the compartment with background porosity,both resonance peaks in this compartment at the lower and higher Helmholtz frequencies decrease,meanwhile,the resonance peak at the lower Helmholtz frequency for the other compartment also decreases,whereas the resonance peak at the higher Helmholtz frequency increases.Both resonance peaks of the admittance functions in the two compartments decrease with increasing the amplitude of fluctuating external pressure coefficients or reference wind speed.
基金Project was supported by National Natural Science Foundation of China(Grant No.62173170).
文摘The successful confinement of the arc by the flux band depends on the welding process parameters for achieving single-pass,multi-layer, and ultra-narrow gap welding. The sidewall fusion depth, the width of the heat-affected zone, and the line energy are utilized as comprehensive indications of the quality of the welded joint. In order to achieve well fusion and reduce the heat input to the base metal.Three welding process characteristics were chosen as the primary determinants, including welding voltage, welding speed, and wire feeding speed. The metamodel of the welding quality index was built by the orthogonal experiments. The metamodel and NSGA-Ⅱ(Non-dominated sorting genetic algorithm Ⅱ) were combined to develop a multi-objective optimization model of ultra-narrow gap welding process parameters. The results showed that the optimized welding process parameters can increase the sidewall fusion depth, reduce the width of the heataffected zone and the line energy, and to some extent improve the overall quality of the ultra-narrow gap welding process.
文摘In this paper a mixed finite element method for the convection dominated diffusion problems with small parameter ε is presented,the effect of the parameter ε on the approximation error is considered and a sufficient condition for optimal error estimates is derived.The paper also shows that under some conditions,the standard finite element method only gives a bounded solution,however the mixed finite element method gives a convergent one. Received March 1,1997. 1991 MR Subject Classification: 65N30,65M15.
文摘Objective:To investigate the correlation of variables between dominant and non-dominant eyes in healthy young people.Methods:300 cases(600 eyes)of healthy young volunteers recruited in our hospital from March 2020 to February 2022were selected as the research objects.The general data of the volunteers were collected and the dominant eye,diopter,biological parameters and retinal blood flow density were detected.We compared all the test indexes of volunteers with different dominant eyes,and compared the refractive parameters,biological parameters and retinal blood flow density between the dominant and non-dominant eyes of volunteers.Results:Among the 300volunteers,62.67%(188/300)had the right eye as the dominant eye and 37.33%(112/300)had the left eye as the dominant eye.There was no significant difference in gender,BMI and equivalent spherical lens(SE)among the subjects with different dominant eyes(P>0.05).The SE and spherical diopter(S)of dominant eye were higher than that of non-dominant eye(P<0.05),but there was no significant difference between the dominant and non-dominant eye(C)(P>0.05);There was no significant difference in SE and C between dominant and non-dominant eye in volunteers with SE difference≤0.5 D and 0.51-1.25 D(P>0.05),and spherical diopter(S)of dominant eye was higher than that of non-dominant eye(P<0.05);The difference of SE was 1.26-2.00 D,>2.00 D,the SE and spherical diopter(S)of dominant eye were higher than those of non-dominant eye(P<0.05),but there was no significant difference between the dominant and non-dominant eye C(P>0.05).The levels of RA and CA in the dominant eye of 300 volunteers were lower than those in the non-dominant eye.The RA and CA levels of the dominant eye were lower than those of the non-dominant eye in volunteers with RA difference≤0.50 D,0.51-1.25 D,1.26-2.00 D,>2.00 D(P<0.05).There was no significant difference in the levels of axial length(AL),central corneal thickness(CCT),anterior chamber depth(ACD)and lens thickness(LT)between the dominant and non-dominant eyes(P>0.05).The levels of superficial retinal capillary layer(SVC),deep retinal capillary layer(DVC)and mean retinal blood flow density(RET)in dominant eyes were lower than those in non-dominant eyes.The level of AC in non-dominant eyes was higher than that in non-dominant eyes(P<0.05).Conclusion:The dominant eye of healthy young people is mostly the right eye,which has nothing to do with gender,age and BMI.Meanwhile,the biological parameters between the dominant and non-dominant eye were basically the same,the mean retinal blood flow density of the dominant eye was lower than that of the non-dominant eye,but its AC was higher than that of the non-dominant eye.
文摘This paper is motivated by the concept of the signed k-domination problem and dedicated to the complexity of the problem on graphs. For any fixed nonnegative integer k, we show that the signed k-domination problem is NP-complete for doubly chordal graphs. For strongly chordal graphs and distance-hereditary graphs, we show that the signed k-domination problem can be solved in polynomial time. We also show that the problem is linear-time solvable for trees, interval graphs, and chordal comparability graphs.
基金重庆市教育委员会科学技术研究项目“三峡水库消落带土地利用变化对土壤抗侵蚀的影响研究”(KJQN202000502)重庆师范大学基金项目“酸沉降和土壤施加磷对马尾松林碳氮磷化学计量特征的影响研究”(20XLB005)中挪国际合作项目“N_(2)O emissions from N saturated subtropical forest in South China”(193725/S30)。
