Effectiveness and safety of a sports mouthguard depend on its thickness and material, and the thermoforming process affects these. The purpose of this study was to clarify the effects of differences in molding mechani...Effectiveness and safety of a sports mouthguard depend on its thickness and material, and the thermoforming process affects these. The purpose of this study was to clarify the effects of differences in molding mechanisms on the lower molding temperature limit and molding time in dental thermoforming. Ethylene vinyl acetate resin mouthguard sheet and two thermoforming machines;vacuum blower molding machine and vacuum ejector/pressure molding machine were used. The molding pressures for suction molding were −0.018 MPa for vacuum blower molding and −0.090 MPa for vacuum ejector molding, and for pressure molding was set to 0.090 MPa or 0.450 MPa. Based on the manufacturer’s standard molding temperature of 95˚C, the molding temperature was lowered in 2.5˚C increments to determine the lower molding temperature limit at which no molding defects occurred. In order to investigate the difference in molding time depending on the molding mechanism, the duration of molding pressure was adjusted in each molding machine, and the molding time required to obtain a sample without molding defects was measured. The molding time of each molding machine were compared using one-way analysis of variance. The lower molding temperature limit was 90.0˚C for the vacuum blower machine, 77.5˚C for the vacuum ejector machine, 77.5˚C for the pressure molding machine at 0.090 MPa, and 67.5˚C for the pressure molding machine at 0.45 MPa. The lower molding temperature limit was higher for lower absolute values of molding pressure. The molding time was shorter for pressure molding than for suction molding. Significant differences were observed between all conditions except between the pressure molding machine at 0.090 MPa and 0.45 MPa (P < 0.01). A comparison of the differences in lower molding temperature limit and molding time due to molding mechanisms in dental thermoforming revealed that the lower molding temperature limit depends on the molding pressure and that the molding time is longer for suction molding than for pressure molding.展开更多
In this paper, the method of relaxed boundary conditions is applied to rectangular plates with edges which are a sort of the mixture of simply supported portions and clamped portions, so that the lower limit of fundam...In this paper, the method of relaxed boundary conditions is applied to rectangular plates with edges which are a sort of the mixture of simply supported portions and clamped portions, so that the lower limit of fundamental frequency of such plates is evaluated. A kind of polynomial satisfying the displacement boundary conditions is designed, os that it is enabled to evaluate the upper limit of fundamental frequency by Ritz' method. The practical calculation examples solved by these methods have given satisfactory results. At the end of this paper, it is pointed out that the socalled exact solution of such plates usually evaluated by the force superposition method is essentially a kind of lower limit of solution, if the truncated error of series which occurs in actual calculation is considered.展开更多
Let x 1,x 2,… be independent identically distributed (i.i.d.) random variables, in which x n=0 or 1 and the probability of ｛x n=1｝ is p. Here p is unknown. Let τ be any finite stopping ...Let x 1,x 2,… be independent identically distributed (i.i.d.) random variables, in which x n=0 or 1 and the probability of ｛x n=1｝ is p. Here p is unknown. Let τ be any finite stopping time for (x n,n1). For any sequential sample (x 1,x 2,…,x τ ) and γ∈(0,1), we have given an optimal confidence limit of p with confidence level γ . Some related problems are also discussed.展开更多
For any given positive integer m, let X_i, 1 ≤ i ≤ m be m independent random variables with distributions F_i, 1 ≤ i ≤ m. When all the summands are nonnegative and at least one of them is heavy-tailed, we prove th...For any given positive integer m, let X_i, 1 ≤ i ≤ m be m independent random variables with distributions F_i, 1 ≤ i ≤ m. When all the summands are nonnegative and at least one of them is heavy-tailed, we prove that the lower limit of the ratio ■equals 1 as x →∞. When the summands are real-valued, we also obtain some asymptotic results for the tail probability of the sums. Besides, a local version as well as a density version of the above results is also presented.展开更多
A design of a slot bushing with a volumetric field has been developed, which allows to produce continuous fibers from melts with difficult processing characteristics in order to produce fibers with better operating ch...A design of a slot bushing with a volumetric field has been developed, which allows to produce continuous fibers from melts with difficult processing characteristics in order to produce fibers with better operating characteristics. The operability of the design was confirmed when solving two problems of special technological complexity. 1. 400 and 800 orifice bushings for production of continuous fibers from the basalt melt have been developed and recommended for manufacture. 2. The process of production of continuous fibers from standard glass using 2400 orifice bushing with perforated plates instead of orifice tips without air cooling, has been realized for the first time.展开更多
A method of localization is proposed to lower the high order of equations in FEM calcula- tion for the stability of a complex thin-walled structure.The localized analysis enables us to obtain both the upper and lower ...A method of localization is proposed to lower the high order of equations in FEM calcula- tion for the stability of a complex thin-walled structure.The localized analysis enables us to obtain both the upper and lower limits for the bifurcating point in a whole linear elastic structural system,as well as an ap- proximate solution to asymptotic post-buckling problem.Some numerical examples are included.展开更多
Discontinuous lining is a special form of support in underground excavation. Based on the method of plastic limit analysis, it is found the upper and the lower bound solution of the pressure of circular discontinuous ...Discontinuous lining is a special form of support in underground excavation. Based on the method of plastic limit analysis, it is found the upper and the lower bound solution of the pressure of circular discontinuous lining and discussed support parameter of discontinuous lining and its applicable conditions , which provides theoretical basis for the design and calculation of discontinuous lining.展开更多
介绍了中国《建筑隔震设计标准》(GB/T 51408—2021)(以下简称《隔标》)和美国Minimum design loads and associated criteria for buildings and other structures(ASCE 7-16)隔震设计的相关要求,并针对基于《建筑抗震设计规范》(GB 50...介绍了中国《建筑隔震设计标准》(GB/T 51408—2021)(以下简称《隔标》)和美国Minimum design loads and associated criteria for buildings and other structures(ASCE 7-16)隔震设计的相关要求,并针对基于《建筑抗震设计规范》(GB 50011—2010)(2016年版)(以下简称《抗规》)设计的某9度区近场隔震结构,进行了两国规范的设计对比。按《抗规》设计的隔震结构,仍然能满足《隔标》的设计要求。ASCE 7-16对于隔震支座考虑了老化和环境、测试、制造等因素引起的性能参数变化,并按隔震支座的上限及下限属性进行了结构设计。基于相同地震概率水准(50年超越概率2%)的设计对比研究表明,ASCE 7-16的等效侧力法计算值高于《隔标》,按ASCE 7-16要求选择的地震波反应谱明显高于《隔标》,其时程分析结果也大于中国规范,对隔震支座的性能要求更高。展开更多
Estimation of the plant-available water capacity(PAWC)of soils at a regional scale helps in adopting better land use planning,developing suitable irrigation schedules for crops,and optimizing the use of scarce water r...Estimation of the plant-available water capacity(PAWC)of soils at a regional scale helps in adopting better land use planning,developing suitable irrigation schedules for crops,and optimizing the use of scarce water resources.In the current study,72 soil profiles were sampled from the Barossa region of South Australia to estimate pedo-transfer functions deduced from easily estimated soil properties.These functions were then used to estimate the fixed(10 and 33 kPa)and dynamic pressure head(h_(fc))water contents at field capacity(FC)for minimum drainage flux(0.01 and 0.001 cm d^(-1)),which serves as the upper boundary for plant-available water in soils.The estimated residual water content was corrected for subsoil constraints,especially the exchangeable sodium percentage(ESP).The results showed that the mean values of h_(fc)in sand-dominated light and medium textured soils(i.e.,sand,loamy sand,sandy loam,and loam)varied in a narrow range(15.8-18.2 kPa),whereas those in the clay-dominated heavy textured soils(i.e.,clay loam)showed a wide range(11.3-49.3 kPa).There were large differences in PAWC for dynamic FC(PAWC_(fc))and fixed FC at 10 kPa(PAWC10),33 kPa(PAWC33),and a mix of 10and 33 kPa(PAWC_(10,33))pressure heads depending on soil texture.Normally,the difference between PAWC at 10 kPa and h_(fc)(ΔPAWC_(10))was positive,whereas that between 33 kPa and h_(fc)(ΔPAWC_(33))was negative across all sites.Nevertheless,the estimation of PAWC assuming a fixed FC at 10 and 33 kPa pressures(i.e.,PAWC_(10,33))for sandy,clay,and silty soils reduced the difference between fixed and dynamic pressure PAWCs to<10% across the region.The estimation of PAWC was improved by incorporating the impact of subsoil constraints,such as high ESP,which was more pronounced for clay and silty soils.These findings demonstrate the inherent inconsistencies between static pressure and flux-based dynamic FC estimations in soils.Soil heterogeneity,intra-texture variability,subsoil constraints,and swell-shrink clays can have great impacts on the water retention capacity in response to dynamic and fixed pressure FC values.展开更多
文摘Effectiveness and safety of a sports mouthguard depend on its thickness and material, and the thermoforming process affects these. The purpose of this study was to clarify the effects of differences in molding mechanisms on the lower molding temperature limit and molding time in dental thermoforming. Ethylene vinyl acetate resin mouthguard sheet and two thermoforming machines;vacuum blower molding machine and vacuum ejector/pressure molding machine were used. The molding pressures for suction molding were −0.018 MPa for vacuum blower molding and −0.090 MPa for vacuum ejector molding, and for pressure molding was set to 0.090 MPa or 0.450 MPa. Based on the manufacturer’s standard molding temperature of 95˚C, the molding temperature was lowered in 2.5˚C increments to determine the lower molding temperature limit at which no molding defects occurred. In order to investigate the difference in molding time depending on the molding mechanism, the duration of molding pressure was adjusted in each molding machine, and the molding time required to obtain a sample without molding defects was measured. The molding time of each molding machine were compared using one-way analysis of variance. The lower molding temperature limit was 90.0˚C for the vacuum blower machine, 77.5˚C for the vacuum ejector machine, 77.5˚C for the pressure molding machine at 0.090 MPa, and 67.5˚C for the pressure molding machine at 0.45 MPa. The lower molding temperature limit was higher for lower absolute values of molding pressure. The molding time was shorter for pressure molding than for suction molding. Significant differences were observed between all conditions except between the pressure molding machine at 0.090 MPa and 0.45 MPa (P < 0.01). A comparison of the differences in lower molding temperature limit and molding time due to molding mechanisms in dental thermoforming revealed that the lower molding temperature limit depends on the molding pressure and that the molding time is longer for suction molding than for pressure molding.
文摘In this paper, the method of relaxed boundary conditions is applied to rectangular plates with edges which are a sort of the mixture of simply supported portions and clamped portions, so that the lower limit of fundamental frequency of such plates is evaluated. A kind of polynomial satisfying the displacement boundary conditions is designed, os that it is enabled to evaluate the upper limit of fundamental frequency by Ritz' method. The practical calculation examples solved by these methods have given satisfactory results. At the end of this paper, it is pointed out that the socalled exact solution of such plates usually evaluated by the force superposition method is essentially a kind of lower limit of solution, if the truncated error of series which occurs in actual calculation is considered.
文摘Let x 1,x 2,… be independent identically distributed (i.i.d.) random variables, in which x n=0 or 1 and the probability of ｛x n=1｝ is p. Here p is unknown. Let τ be any finite stopping time for (x n,n1). For any sequential sample (x 1,x 2,…,x τ ) and γ∈(0,1), we have given an optimal confidence limit of p with confidence level γ . Some related problems are also discussed.
基金Supported by the National Natural Science Foundation of China(no.11401415)Tian Yuan Foundation(nos.11226208 and 11426139)+2 种基金Natural Science Foundation of the Jiangsu Higher Education Institutions of China(no.13KJB110025)Postdoctoral Research Program of Jiangsu Province of China(no.1402111C)Jiangsu Overseas Research and Training Program for Prominent University Young and Middle-aged Teachers and Presidents
文摘For any given positive integer m, let X_i, 1 ≤ i ≤ m be m independent random variables with distributions F_i, 1 ≤ i ≤ m. When all the summands are nonnegative and at least one of them is heavy-tailed, we prove that the lower limit of the ratio ■equals 1 as x →∞. When the summands are real-valued, we also obtain some asymptotic results for the tail probability of the sums. Besides, a local version as well as a density version of the above results is also presented.
文摘A design of a slot bushing with a volumetric field has been developed, which allows to produce continuous fibers from melts with difficult processing characteristics in order to produce fibers with better operating characteristics. The operability of the design was confirmed when solving two problems of special technological complexity. 1. 400 and 800 orifice bushings for production of continuous fibers from the basalt melt have been developed and recommended for manufacture. 2. The process of production of continuous fibers from standard glass using 2400 orifice bushing with perforated plates instead of orifice tips without air cooling, has been realized for the first time.
基金Project supported by National Natural Science Foundation of China
文摘A method of localization is proposed to lower the high order of equations in FEM calcula- tion for the stability of a complex thin-walled structure.The localized analysis enables us to obtain both the upper and lower limits for the bifurcating point in a whole linear elastic structural system,as well as an ap- proximate solution to asymptotic post-buckling problem.Some numerical examples are included.
文摘Discontinuous lining is a special form of support in underground excavation. Based on the method of plastic limit analysis, it is found the upper and the lower bound solution of the pressure of circular discontinuous lining and discussed support parameter of discontinuous lining and its applicable conditions , which provides theoretical basis for the design and calculation of discontinuous lining.
文摘介绍了中国《建筑隔震设计标准》(GB/T 51408—2021)(以下简称《隔标》)和美国Minimum design loads and associated criteria for buildings and other structures(ASCE 7-16)隔震设计的相关要求,并针对基于《建筑抗震设计规范》(GB 50011—2010)(2016年版)(以下简称《抗规》)设计的某9度区近场隔震结构,进行了两国规范的设计对比。按《抗规》设计的隔震结构,仍然能满足《隔标》的设计要求。ASCE 7-16对于隔震支座考虑了老化和环境、测试、制造等因素引起的性能参数变化,并按隔震支座的上限及下限属性进行了结构设计。基于相同地震概率水准(50年超越概率2%)的设计对比研究表明,ASCE 7-16的等效侧力法计算值高于《隔标》,按ASCE 7-16要求选择的地震波反应谱明显高于《隔标》,其时程分析结果也大于中国规范,对隔震支座的性能要求更高。
文摘Estimation of the plant-available water capacity(PAWC)of soils at a regional scale helps in adopting better land use planning,developing suitable irrigation schedules for crops,and optimizing the use of scarce water resources.In the current study,72 soil profiles were sampled from the Barossa region of South Australia to estimate pedo-transfer functions deduced from easily estimated soil properties.These functions were then used to estimate the fixed(10 and 33 kPa)and dynamic pressure head(h_(fc))water contents at field capacity(FC)for minimum drainage flux(0.01 and 0.001 cm d^(-1)),which serves as the upper boundary for plant-available water in soils.The estimated residual water content was corrected for subsoil constraints,especially the exchangeable sodium percentage(ESP).The results showed that the mean values of h_(fc)in sand-dominated light and medium textured soils(i.e.,sand,loamy sand,sandy loam,and loam)varied in a narrow range(15.8-18.2 kPa),whereas those in the clay-dominated heavy textured soils(i.e.,clay loam)showed a wide range(11.3-49.3 kPa).There were large differences in PAWC for dynamic FC(PAWC_(fc))and fixed FC at 10 kPa(PAWC10),33 kPa(PAWC33),and a mix of 10and 33 kPa(PAWC_(10,33))pressure heads depending on soil texture.Normally,the difference between PAWC at 10 kPa and h_(fc)(ΔPAWC_(10))was positive,whereas that between 33 kPa and h_(fc)(ΔPAWC_(33))was negative across all sites.Nevertheless,the estimation of PAWC assuming a fixed FC at 10 and 33 kPa pressures(i.e.,PAWC_(10,33))for sandy,clay,and silty soils reduced the difference between fixed and dynamic pressure PAWCs to<10% across the region.The estimation of PAWC was improved by incorporating the impact of subsoil constraints,such as high ESP,which was more pronounced for clay and silty soils.These findings demonstrate the inherent inconsistencies between static pressure and flux-based dynamic FC estimations in soils.Soil heterogeneity,intra-texture variability,subsoil constraints,and swell-shrink clays can have great impacts on the water retention capacity in response to dynamic and fixed pressure FC values.
