In Maizhokunggar County of Lhasa City,the Xizang Autonomous Region,a precious intangible cultural heritage is preserved-the traditional craft of Zaxoi drum making,which carries profound historical and cultural signifi...In Maizhokunggar County of Lhasa City,the Xizang Autonomous Region,a precious intangible cultural heritage is preserved-the traditional craft of Zaxoi drum making,which carries profound historical and cultural significance.After hundreds of years,its unique value continues to shine through the passage of time.For more than 40 years,Kongcho Dondrup,an inheritor of this craftsmanship,has poured his heart into preserving and promoting this ancient art.展开更多
A study has been reported on <sup>208</sup>Pb/<sup>206</sup>Pb and <sup>207</sup>Pb/<sup>206</sup>Pb ratio variations in ancient drums and Cu-., Pb- ores from Guangxi, C...A study has been reported on <sup>208</sup>Pb/<sup>206</sup>Pb and <sup>207</sup>Pb/<sup>206</sup>Pb ratio variations in ancient drums and Cu-., Pb- ores from Guangxi, China and can indicate that the Cu- and Pb- bearing ores for making the Beiliu and the Lingshan type drums were taken from Tongshiling of Beiliu County and its vicinity, that were not only ancient sites for smelting the copper ores, but possibly also for casting the bronze drums. Some of the Lengshuichong type drums have abnormal Pb isotopic ratios, which means that they were made of special ore sources, one of the possibilities is that the ore material or the drums were transported from South- East Asia to Guangxi Province, because they have been excavated there too.展开更多
A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is ba...A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is based on the assumptions that the difference of temperature along the longitudinal axis of the boiler drum is negligible with changes only in the radial direction and the circumferential direction, and that the outer surface of drum is thermaUy insulated. Combining this model with the control-volume method provides temperatures at different points on a cross-section of the drum. With the temperature data, the stresses and the life expectancy of the boiler drum are derived according to the ASME code. Applying this method to the cold start-up process of a 300 MW boiler demonstrated the absence of errors caused by the boundary condition assumptions on the inner surface of the drum and testified that the method is an applicable technique for the online stress monitoring and fatigue life analysis of boiler drums.展开更多
Adding a moving baffle to the drum is a new way to enhance the motion and mixing of particles in rotating drums.To obtain its influence on binary particles,horizontal rotating drums provided with a moving baffle were ...Adding a moving baffle to the drum is a new way to enhance the motion and mixing of particles in rotating drums.To obtain its influence on binary particles,horizontal rotating drums provided with a moving baffle were investigated by discrete element method(DEM).AtΩ=15 r/min,increasing the length of moving baffle can increase the fluctuation amplitude of average particle velocity.AtΩ=60 r/min,the influence of the moving baffle on the average velocity fluctuation tends to be more random.At both rotational speeds,the moving baffle causes the average particle velocity to fluctuate more sharply.The moving baffle can enhance particle mixing.AtΩ=15 r/min,the moving baffle with length ofδ=1/3 can best enhance particle mixing.However,atΩ=60 r/min,only the moving baffle with a specific length(δ=1/4)can enhance mixing.This basic research has a positive reference value for the application of the moving baffle in industry.展开更多
An analysis of the efficiency of the ginning of cotton fibers with two saw cylinders has been carried out. In comparison to a one-cylinder machine, the 2 cylinder approach can help to preserve the natural characterist...An analysis of the efficiency of the ginning of cotton fibers with two saw cylinders has been carried out. In comparison to a one-cylinder machine, the 2 cylinder approach can help to preserve the natural characteristics of cotton fiber and seeds. This technology allows economizing electricity and decreasing damage to fiber and also increases the productivity of the machine.展开更多
One of the primary reasons leading to bulging and cracking in a coke drum is the severe temperature gradient due to cyclic temperature variation. Based on the twodimensional heat conduction theory, an analytical solut...One of the primary reasons leading to bulging and cracking in a coke drum is the severe temperature gradient due to cyclic temperature variation. Based on the twodimensional heat conduction theory, an analytical solution of the transient temperature field in the coke drum is obtained, which is different from the known FEM results. The length of the coke drum is considered finite. The dynamic boundary conditions caused by fluid uninterrupted rising in oiling and watering stages are simulated with the iteration method. Numerical results show that the present theoretical model can accurately describe basic features of the transient temperature field in the coke drum. Effects of the geometry of the coke drum and the rising velocity of quench water on the axial temperature gradient are also discussed.展开更多
Braking efficiency is characterized by reduced braking time and distance,and therefore passenger safety depends on the design of the braking system.During the braking of a vehicle,the braking system must dissipate the...Braking efficiency is characterized by reduced braking time and distance,and therefore passenger safety depends on the design of the braking system.During the braking of a vehicle,the braking system must dissipate the kinetic energy by transforming it into heat energy.A too high temperature can lead to an almost total loss of braking efficiency.An excessive rise in brake temperature can also cause surface cracks extending to the outside edge of the drum friction surface.Heat transfer and temperature gradient,not to forget the vehicle’s travel environment(high speed,heavy load,and steeply sloping road conditions),must thus be the essential criteria for any brake system design.The aim of the present investigation is to analyze the thermal behavior of different brake drum designs during the single emergency braking of a heavy-duty vehicle on a steeply sloping road.The calculation of the temperature field is performed in transient mode using a three-dimensional finite element model assuming a constant coefficient of friction.In this study,the influence of geometrical brake drum configurations on the thermal behavior of brake drums with two different materials in grey cast iron FG200 and aluminum alloy 356.0 reinforced with silicon carbide(SiC)particles is analyzed under extreme vehicle braking conditions.The numerical simulation results obtained using FE software ANSYS are qualitatively compared with the results already published in the literature.展开更多
The double drum drive is widely used on the mine belt conveyor, which are divided the rigid connected double drums and separately driving double drums according to connected method of two drums. Because of the change ...The double drum drive is widely used on the mine belt conveyor, which are divided the rigid connected double drums and separately driving double drums according to connected method of two drums. Because of the change of real work condition, the load distribution is changed on the two drive drums, which may produce a slippage between a drum and belt. Slippage may intensify the wear of the drum, and sometimes causing the fire of the belt. This restricts the development toward narrow belt, high velocity and large power of belt conveyor. In this paper, the factors affecting the load distribution of two drums of double drum belt conveyor are systematically analyzed and some computing formulas derived, by these formulas, the actual lcad distribution on the two drums of rigid connected or separately driving belt conveyor can be separately calculated.These formulas also can be as the theory base for adjusting the driving force of two drums.展开更多
The objective of this original pilot study was to determine if the Drums Alive<span style="white-space:nowrap;"><sup>®</sup></span> Kids Beats intervention could provide stati...The objective of this original pilot study was to determine if the Drums Alive<span style="white-space:nowrap;"><sup>®</sup></span> Kids Beats intervention could provide statistically significant improvements to physical and motor skill performance on participants with Developmental Delays (DD) using the Dusseldorf Motor-Proficiency-Test for children (MOT 4-6) model. The researchers selected the research-based Drums Alive Kids Beat intervention because of its multidisciplinary methodology that in previous studies demonstrated positive effects on physiological, psychological, neurological, educational, rhythmical, and socio-emotional literacy. Facilitators used standardized Drums Alive approved lesson plans and equipment to conduct the intervention through a battery of music, movement and drumming-centered exercises and activities. The 30 participants were German students between 4.9 and 10.2 years of age, without any inclusion or exclusion characteristics, who were divided into three groups consisting of two intervention groups: IG Kindergarten (IG Kinder), IG Elementary<span style="font-family:;" "=""><span style="font-family:Verdana;"> (IG Elem) with varied physical, social, and emotional DD that affected gross and fine motor skills, movement, coordination, and behavioral control;and, a Control Group (CG) that had normal physical and motor skill development (</span><b><span style="font-family:Verdana;">Table 1</span></b><span style="font-family:Verdana;">). The results of the study suggested that the Drums Alive Kids Beats intervention provided statistically significant improvements in physical and motor skill performance in children with DD, namely, 24% improvement (IG Kinder), 14% (IG Elem) vice a minor 4% improvement (CG). Of note, during this study to measure physical capability pre- and post-intervention, the facilitators noticed significant improvements in behavior in both IG groups;therefore, they chose to conduct a collateral study to measure six behavioral domains which will be documented in a future publication to demonstrate the exclusive relationship between the Drums Alive Kids Beats intervention and improvement in behavior.</span></span>展开更多
The purpose of this study was to determine if the Drums Alive Kids Beats intervention could improve behavior in children with developmental delays (DD). The original pilot study that this study on behavior is linked t...The purpose of this study was to determine if the Drums Alive Kids Beats intervention could improve behavior in children with developmental delays (DD). The original pilot study that this study on behavior is linked to is titled, “The Effects of a Drums Alive<sup> </sup>Kids Beats Intervention on the Physical Performance and Motor Skills of Children with Developmental Delays,” which was published in the December edition of the Open Journal of Pediatrics (OJPED, Vol.11 No.4 2021). During the facilitation of said intervention on physical and motor skills, the facilitators noticed unanticipated improvements in behavior, both individually and as a community through better awareness, self-control, self-efficacy, social interaction, and positive energy. Therefore, while maintaining the integrity of the MOT 4 - 6 testing protocols and Drums Alive intervention, a parallel study was conducted to objectively measure six behavioral domains, namely, motivation, impulse control, coordination, concentration, implementation of tasks, and creativity using a self-designed measurement tool with three elements for each domain that was approved by Dr. Heiner Lagenkamp, Department of Sports and Physical Activities, Teaching and Research, Ruhr University, Germany. The 20 participants were German students between 5.10 and 10.2 years of age with no inclusion or exclusion characteristics who were divided into two intervention groups, IG Kindergarten (IG Kinder) and IG Elementary (IG Elem), with varied DD, i.e., transgressive behavior, ADHD, ADD, autism, anger management, visual acuity, self-control, and self-esteem. During the MOT 4 - 6 study and Drums Alive Kids Beats intervention, the facilitators monitored and assessed each participant for pre- and post-performance vis a vis behavior concurrently with physical and motoric skills. As the original study provided statistically significant improvements of between 14% - 24% in physical and motor skill performance with regards to overall scoring and 7 subdivisions of tasks, the results of this parallel study on behavior, with its 6 domains and 18 elements of between 24% - 28%, were even more compelling. The evidence indicated that the Drums Alive Kids Beats intervention with its multidisciplinary approach of music, movement, and drumming, could be used as an effective tool and therapeutic approach to improve behavior in children with developmental delays.展开更多
In this paper, we study the effects of the presence and shape of side walls and of the overall length of rotating cylindrical drums on the mixing of particles with differing sizes by application of the discrete elemen...In this paper, we study the effects of the presence and shape of side walls and of the overall length of rotating cylindrical drums on the mixing of particles with differing sizes by application of the discrete element method (DEM). By varying the semi-axis of the spheroidally shaped side walls and the length of the overall drum, we observe the formation of circulation patterns near the side walls. Although there is a vast amount of literature studying mixing regimes in rotating drums, little is known about the effect of the side walls of the drum on particle mixing. The results of our study demonstrate that introducing curved side walls induces a strong circulation pattern near these side walls, but has, paradoxically, a negative impact on mixing and actually promotes segregation. The cause for this segregation is the difference in velocity of differently sized particles near the curved side walls. Large particles accumulate at the curved side walls, whereas small particles move away from the curved side walls. When the length of the drum is increased, the overall effect of the side walls is decreased, although it does remain observable, even in very large drums.展开更多
Ⅰ. INTRODUCTIONBronze drum culture was well developed in China since more than 2500 years ago to 1828 A.D. Ancient drums are representatives of the historical culture of minority people living in southern China. The ...Ⅰ. INTRODUCTIONBronze drum culture was well developed in China since more than 2500 years ago to 1828 A.D. Ancient drums are representatives of the historical culture of minority people living in southern China. The early drums, Wanjiaba and Shizhaishan types unearthed in Yunnan have been investigated by lead isotopes in this note. The scientific basis for the lead method was described in Refs. [2, 3] and the isotopic ratios were corrected with the NBS-981 standard shown in Table 1. Based on the experimental results, we would like展开更多
In this paper, we study the asymptotics of the spectrum of the Dirichlet （or Neumann） Laplacian in a bounded open set ΩR<sup>n</sup>（n≥1） with irregular but nonfractal boundary Ω. We give a partial ...In this paper, we study the asymptotics of the spectrum of the Dirichlet （or Neumann） Laplacian in a bounded open set ΩR<sup>n</sup>（n≥1） with irregular but nonfractal boundary Ω. We give a partial resolution of the Weyl conjecture, i.e. for the counting function Ni（λ）（i=0: Dirichlet; i=i: Neumann）, we have got a precise estimate of the remainder term Ψ<sub>i</sub>（λ）=φ（λ）-N<sub>i</sub>（λ） for large λ, where φ（λ） is the Weyl term. This implies that for the irregular but nonfractal drum Ω, not only the volume |Ω|<sub>n</sub> is spectral invariant but also the area of boundary |Ω|<sub>n-1</sub> might be spectral invariant as well.展开更多
The theory of flow similarity has not been well established for granular flows, in contrast to the case for conventional fluids, owing to a lack of reliable and general constitutive laws for their continuum descrip- t...The theory of flow similarity has not been well established for granular flows, in contrast to the case for conventional fluids, owing to a lack of reliable and general constitutive laws for their continuum descrip- tion. A rigorous investigation of the similarity of velocity fields in different granular systems would he valuable to theoretical studies. However, experimental measurements face technological and physical problems. Numerical simulations that employ the discrete element method （DEM） may be an alterna- tive to experiments by providing similar results, where quantitative analysis could be implemented with virtually no limitation. In this study, the similarity of velocity fields is investigated for the rolling regime of rotating drums by conducting simulations based on the DEM and using graphics processing units. For a constant Froude number, it is found that the particle-to-drum size ratio plays a dominant role in the determination of the velocity field, while the velocity field is much more sensitive to some material properties than to others. The implications of these findings are discussed in terms of establishing theoretical similarity laws for granular flows.展开更多
A regular tetrahedron is the simplest three-dimensional structure and has the largest non-sphericity. Mixing of tetrahedral particles in a thin drum mixer was studied by the soft-sphere-imbedded pseudo- hard particle ...A regular tetrahedron is the simplest three-dimensional structure and has the largest non-sphericity. Mixing of tetrahedral particles in a thin drum mixer was studied by the soft-sphere-imbedded pseudo- hard particle model and compared with that of spherical particles. The two particle types were simulated with different rotation speeds and drum filling levels. The Lacey mixing index and Shannon information entropy were used to explore the effects of sphericity on the mixing and motion of particles. Moreover, the probability density functions and mean values and variances of motion velocities, including translational and rotational, were computed to quantify the differences between the motion features of tetrahedra and spheres. We found that the flow regime depended on the particle shape in addition to the rotation speed and filling level of the drum. The mixing of tetrahedral particles was better than that of spherical particles in the rolling and cascading regimes at a high filling level, whereas it may be poorer when the filling level was low. The Shannon information entropy is better than the Lacey mixing index to evaluate mixing because it can reflect the real change of flow regime from the cataracting to the centrifugal regime, whereas the mixing index cannot.展开更多
Particle distribution in the cross-section of the flighted rotating drum(FRD)is critical to the analysis of heat and mass transfer between gas and solids.In this work,the particle tracking velocimetry(PTV)method is ap...Particle distribution in the cross-section of the flighted rotating drum(FRD)is critical to the analysis of heat and mass transfer between gas and solids.In this work,the particle tracking velocimetry(PTV)method is applied to study the influence of the number of flights on the particle motion in FRDs.The drum,installed with 1,4,8,or 12 rectangular flights,is filled with plastic balls to 15%and operated at various rotating speeds ranging from 10 rpm to 30 rpm.The results show that the number of flights has different effects on the holdup ratio and cascading rate of single flight and active flights.With 8 and 12 flights,the FRD produces a larger and more stable particle ratio of the dilute phase.Moreover,DEM simulations agree with PTV measurements,whereas literature models show significant deviations.展开更多
The skirt-to-shell junction weld on coke drums is susceptible to fatigue failure due to severe thermal cyclic stresses. One method to decrease junction stress is to add slots near the top of the skirt, thereby reducin...The skirt-to-shell junction weld on coke drums is susceptible to fatigue failure due to severe thermal cyclic stresses. One method to decrease junction stress is to add slots near the top of the skirt, thereby reducing the local stiffness close to the weld. The most common skirt slot design is thin relative to its circumferential spacing. A new slot design, which is significantly wider, is proposed. In this study, thermal-mechanical elastoplastic 3-D finite element models of coke drums are created to analyze the effect of different skirt designs on the stress/strain field near the shell-to-skirt junction weld, as well as any other critical stress locations in the overall skirt design. The results confirm that the inclusion of the conventional slot design effectively reduces stress in the junction weld. However, it has also been found that the critical stress location migrates from the shell-to-skirt junction weld to the slot ends. A method is used to estimate the fatigue life near the critical areas of each skirt slot design. It is found that wider skirt slots provide a significant improvement on fatigue life in the weld and slot area.展开更多
LetΩ,with finite Lebesgue measure|Ω|,be a non-empty open subset of R,andΩ=∪∞j-1Ωj,where the open setsΩj are pairwise disjoint and the boundaryГ=■Ωhas Minkowski dimension D∈(0,1).In this paper we study the D...LetΩ,with finite Lebesgue measure|Ω|,be a non-empty open subset of R,andΩ=∪∞j-1Ωj,where the open setsΩj are pairwise disjoint and the boundaryГ=■Ωhas Minkowski dimension D∈(0,1).In this paper we study the Dirichlet eigenvalues problem on the domainΩand give the exact second asymptotic term for the eigenvalues,which is related to the Minkowski dimension D.Meanwhile,we give sharp lower bound estimates for Dirichlet eigenvalues for such one-dimensional fractal domains.展开更多
Countries from the Global South strengthen ties,showcase innovation and expand cooperation at the eighth CIIE Ahuge crowd gathered at the Ugandan Pavilion in the National Exhibition Hall of the eighth China Internatio...Countries from the Global South strengthen ties,showcase innovation and expand cooperation at the eighth CIIE Ahuge crowd gathered at the Ugandan Pavilion in the National Exhibition Hall of the eighth China International Import Expo(CIIE)in Shanghai on the morning of 6 November,as performers danced to the passionate beats of African drums.展开更多
文摘In Maizhokunggar County of Lhasa City,the Xizang Autonomous Region,a precious intangible cultural heritage is preserved-the traditional craft of Zaxoi drum making,which carries profound historical and cultural significance.After hundreds of years,its unique value continues to shine through the passage of time.For more than 40 years,Kongcho Dondrup,an inheritor of this craftsmanship,has poured his heart into preserving and promoting this ancient art.
文摘A study has been reported on <sup>208</sup>Pb/<sup>206</sup>Pb and <sup>207</sup>Pb/<sup>206</sup>Pb ratio variations in ancient drums and Cu-., Pb- ores from Guangxi, China and can indicate that the Cu- and Pb- bearing ores for making the Beiliu and the Lingshan type drums were taken from Tongshiling of Beiliu County and its vicinity, that were not only ancient sites for smelting the copper ores, but possibly also for casting the bronze drums. Some of the Lengshuichong type drums have abnormal Pb isotopic ratios, which means that they were made of special ore sources, one of the possibilities is that the ore material or the drums were transported from South- East Asia to Guangxi Province, because they have been excavated there too.
基金Funded by the National Science and Technology Support Project of China (No. 2006BAA03B02-03)
文摘A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is based on the assumptions that the difference of temperature along the longitudinal axis of the boiler drum is negligible with changes only in the radial direction and the circumferential direction, and that the outer surface of drum is thermaUy insulated. Combining this model with the control-volume method provides temperatures at different points on a cross-section of the drum. With the temperature data, the stresses and the life expectancy of the boiler drum are derived according to the ASME code. Applying this method to the cold start-up process of a 300 MW boiler demonstrated the absence of errors caused by the boundary condition assumptions on the inner surface of the drum and testified that the method is an applicable technique for the online stress monitoring and fatigue life analysis of boiler drums.
基金Project(51676032)supported by the National Natural Science Foundation of ChinaProject(IRT_17R19)supported by the Program for Changjiang Scholars and Innovative Research Team in University,China
文摘Adding a moving baffle to the drum is a new way to enhance the motion and mixing of particles in rotating drums.To obtain its influence on binary particles,horizontal rotating drums provided with a moving baffle were investigated by discrete element method(DEM).AtΩ=15 r/min,increasing the length of moving baffle can increase the fluctuation amplitude of average particle velocity.AtΩ=60 r/min,the influence of the moving baffle on the average velocity fluctuation tends to be more random.At both rotational speeds,the moving baffle causes the average particle velocity to fluctuate more sharply.The moving baffle can enhance particle mixing.AtΩ=15 r/min,the moving baffle with length ofδ=1/3 can best enhance particle mixing.However,atΩ=60 r/min,only the moving baffle with a specific length(δ=1/4)can enhance mixing.This basic research has a positive reference value for the application of the moving baffle in industry.
文摘An analysis of the efficiency of the ginning of cotton fibers with two saw cylinders has been carried out. In comparison to a one-cylinder machine, the 2 cylinder approach can help to preserve the natural characteristics of cotton fiber and seeds. This technology allows economizing electricity and decreasing damage to fiber and also increases the productivity of the machine.
基金Project supported by the National Natural Science Foundation of China (Nos. 10372035 and10902043)the Key Laboratory of Diagnosis of Fault in Engineering Structures of Guangdong Province of China
文摘One of the primary reasons leading to bulging and cracking in a coke drum is the severe temperature gradient due to cyclic temperature variation. Based on the twodimensional heat conduction theory, an analytical solution of the transient temperature field in the coke drum is obtained, which is different from the known FEM results. The length of the coke drum is considered finite. The dynamic boundary conditions caused by fluid uninterrupted rising in oiling and watering stages are simulated with the iteration method. Numerical results show that the present theoretical model can accurately describe basic features of the transient temperature field in the coke drum. Effects of the geometry of the coke drum and the rising velocity of quench water on the axial temperature gradient are also discussed.
文摘Braking efficiency is characterized by reduced braking time and distance,and therefore passenger safety depends on the design of the braking system.During the braking of a vehicle,the braking system must dissipate the kinetic energy by transforming it into heat energy.A too high temperature can lead to an almost total loss of braking efficiency.An excessive rise in brake temperature can also cause surface cracks extending to the outside edge of the drum friction surface.Heat transfer and temperature gradient,not to forget the vehicle’s travel environment(high speed,heavy load,and steeply sloping road conditions),must thus be the essential criteria for any brake system design.The aim of the present investigation is to analyze the thermal behavior of different brake drum designs during the single emergency braking of a heavy-duty vehicle on a steeply sloping road.The calculation of the temperature field is performed in transient mode using a three-dimensional finite element model assuming a constant coefficient of friction.In this study,the influence of geometrical brake drum configurations on the thermal behavior of brake drums with two different materials in grey cast iron FG200 and aluminum alloy 356.0 reinforced with silicon carbide(SiC)particles is analyzed under extreme vehicle braking conditions.The numerical simulation results obtained using FE software ANSYS are qualitatively compared with the results already published in the literature.
文摘The double drum drive is widely used on the mine belt conveyor, which are divided the rigid connected double drums and separately driving double drums according to connected method of two drums. Because of the change of real work condition, the load distribution is changed on the two drive drums, which may produce a slippage between a drum and belt. Slippage may intensify the wear of the drum, and sometimes causing the fire of the belt. This restricts the development toward narrow belt, high velocity and large power of belt conveyor. In this paper, the factors affecting the load distribution of two drums of double drum belt conveyor are systematically analyzed and some computing formulas derived, by these formulas, the actual lcad distribution on the two drums of rigid connected or separately driving belt conveyor can be separately calculated.These formulas also can be as the theory base for adjusting the driving force of two drums.
文摘The objective of this original pilot study was to determine if the Drums Alive<span style="white-space:nowrap;"><sup>®</sup></span> Kids Beats intervention could provide statistically significant improvements to physical and motor skill performance on participants with Developmental Delays (DD) using the Dusseldorf Motor-Proficiency-Test for children (MOT 4-6) model. The researchers selected the research-based Drums Alive Kids Beat intervention because of its multidisciplinary methodology that in previous studies demonstrated positive effects on physiological, psychological, neurological, educational, rhythmical, and socio-emotional literacy. Facilitators used standardized Drums Alive approved lesson plans and equipment to conduct the intervention through a battery of music, movement and drumming-centered exercises and activities. The 30 participants were German students between 4.9 and 10.2 years of age, without any inclusion or exclusion characteristics, who were divided into three groups consisting of two intervention groups: IG Kindergarten (IG Kinder), IG Elementary<span style="font-family:;" "=""><span style="font-family:Verdana;"> (IG Elem) with varied physical, social, and emotional DD that affected gross and fine motor skills, movement, coordination, and behavioral control;and, a Control Group (CG) that had normal physical and motor skill development (</span><b><span style="font-family:Verdana;">Table 1</span></b><span style="font-family:Verdana;">). The results of the study suggested that the Drums Alive Kids Beats intervention provided statistically significant improvements in physical and motor skill performance in children with DD, namely, 24% improvement (IG Kinder), 14% (IG Elem) vice a minor 4% improvement (CG). Of note, during this study to measure physical capability pre- and post-intervention, the facilitators noticed significant improvements in behavior in both IG groups;therefore, they chose to conduct a collateral study to measure six behavioral domains which will be documented in a future publication to demonstrate the exclusive relationship between the Drums Alive Kids Beats intervention and improvement in behavior.</span></span>
文摘The purpose of this study was to determine if the Drums Alive Kids Beats intervention could improve behavior in children with developmental delays (DD). The original pilot study that this study on behavior is linked to is titled, “The Effects of a Drums Alive<sup> </sup>Kids Beats Intervention on the Physical Performance and Motor Skills of Children with Developmental Delays,” which was published in the December edition of the Open Journal of Pediatrics (OJPED, Vol.11 No.4 2021). During the facilitation of said intervention on physical and motor skills, the facilitators noticed unanticipated improvements in behavior, both individually and as a community through better awareness, self-control, self-efficacy, social interaction, and positive energy. Therefore, while maintaining the integrity of the MOT 4 - 6 testing protocols and Drums Alive intervention, a parallel study was conducted to objectively measure six behavioral domains, namely, motivation, impulse control, coordination, concentration, implementation of tasks, and creativity using a self-designed measurement tool with three elements for each domain that was approved by Dr. Heiner Lagenkamp, Department of Sports and Physical Activities, Teaching and Research, Ruhr University, Germany. The 20 participants were German students between 5.10 and 10.2 years of age with no inclusion or exclusion characteristics who were divided into two intervention groups, IG Kindergarten (IG Kinder) and IG Elementary (IG Elem), with varied DD, i.e., transgressive behavior, ADHD, ADD, autism, anger management, visual acuity, self-control, and self-esteem. During the MOT 4 - 6 study and Drums Alive Kids Beats intervention, the facilitators monitored and assessed each participant for pre- and post-performance vis a vis behavior concurrently with physical and motoric skills. As the original study provided statistically significant improvements of between 14% - 24% in physical and motor skill performance with regards to overall scoring and 7 subdivisions of tasks, the results of this parallel study on behavior, with its 6 domains and 18 elements of between 24% - 28%, were even more compelling. The evidence indicated that the Drums Alive Kids Beats intervention with its multidisciplinary approach of music, movement, and drumming, could be used as an effective tool and therapeutic approach to improve behavior in children with developmental delays.
基金funded by the Deutsche Forschungsgemein-schaft(DFG,German Research Foundation)-Project-ID 422037413-TRR 287.
文摘In this paper, we study the effects of the presence and shape of side walls and of the overall length of rotating cylindrical drums on the mixing of particles with differing sizes by application of the discrete element method (DEM). By varying the semi-axis of the spheroidally shaped side walls and the length of the overall drum, we observe the formation of circulation patterns near the side walls. Although there is a vast amount of literature studying mixing regimes in rotating drums, little is known about the effect of the side walls of the drum on particle mixing. The results of our study demonstrate that introducing curved side walls induces a strong circulation pattern near these side walls, but has, paradoxically, a negative impact on mixing and actually promotes segregation. The cause for this segregation is the difference in velocity of differently sized particles near the curved side walls. Large particles accumulate at the curved side walls, whereas small particles move away from the curved side walls. When the length of the drum is increased, the overall effect of the side walls is decreased, although it does remain observable, even in very large drums.
基金Project supported by Structure Research Laboratory, USTC, Academia Sinica.
文摘Ⅰ. INTRODUCTIONBronze drum culture was well developed in China since more than 2500 years ago to 1828 A.D. Ancient drums are representatives of the historical culture of minority people living in southern China. The early drums, Wanjiaba and Shizhaishan types unearthed in Yunnan have been investigated by lead isotopes in this note. The scientific basis for the lead method was described in Refs. [2, 3] and the isotopic ratios were corrected with the NBS-981 standard shown in Table 1. Based on the experimental results, we would like
基金Partially supported by the National Natural Science Foundation of Chinathe Grant of Chinese State Education Committee.
文摘In this paper, we study the asymptotics of the spectrum of the Dirichlet （or Neumann） Laplacian in a bounded open set ΩR<sup>n</sup>（n≥1） with irregular but nonfractal boundary Ω. We give a partial resolution of the Weyl conjecture, i.e. for the counting function Ni（λ）（i=0: Dirichlet; i=i: Neumann）, we have got a precise estimate of the remainder term Ψ<sub>i</sub>（λ）=φ（λ）-N<sub>i</sub>（λ） for large λ, where φ（λ） is the Weyl term. This implies that for the irregular but nonfractal drum Ω, not only the volume |Ω|<sub>n</sub> is spectral invariant but also the area of boundary |Ω|<sub>n-1</sub> might be spectral invariant as well.
基金supported by the National Key Basic Research Program of China under grant no.2015CB251402the NationalNatural Science Foundation of China under grant nos.21206167, 21225628,and 51106168the Chinese Academy of Sciences under grant nos.XDA07080203(the Strategic Priority Research Program) and XXH12503-02-03-03
文摘The theory of flow similarity has not been well established for granular flows, in contrast to the case for conventional fluids, owing to a lack of reliable and general constitutive laws for their continuum descrip- tion. A rigorous investigation of the similarity of velocity fields in different granular systems would he valuable to theoretical studies. However, experimental measurements face technological and physical problems. Numerical simulations that employ the discrete element method （DEM） may be an alterna- tive to experiments by providing similar results, where quantitative analysis could be implemented with virtually no limitation. In this study, the similarity of velocity fields is investigated for the rolling regime of rotating drums by conducting simulations based on the DEM and using graphics processing units. For a constant Froude number, it is found that the particle-to-drum size ratio plays a dominant role in the determination of the velocity field, while the velocity field is much more sensitive to some material properties than to others. The implications of these findings are discussed in terms of establishing theoretical similarity laws for granular flows.
文摘A regular tetrahedron is the simplest three-dimensional structure and has the largest non-sphericity. Mixing of tetrahedral particles in a thin drum mixer was studied by the soft-sphere-imbedded pseudo- hard particle model and compared with that of spherical particles. The two particle types were simulated with different rotation speeds and drum filling levels. The Lacey mixing index and Shannon information entropy were used to explore the effects of sphericity on the mixing and motion of particles. Moreover, the probability density functions and mean values and variances of motion velocities, including translational and rotational, were computed to quantify the differences between the motion features of tetrahedra and spheres. We found that the flow regime depended on the particle shape in addition to the rotation speed and filling level of the drum. The mixing of tetrahedral particles was better than that of spherical particles in the rolling and cascading regimes at a high filling level, whereas it may be poorer when the filling level was low. The Shannon information entropy is better than the Lacey mixing index to evaluate mixing because it can reflect the real change of flow regime from the cataracting to the centrifugal regime, whereas the mixing index cannot.
文摘Particle distribution in the cross-section of the flighted rotating drum(FRD)is critical to the analysis of heat and mass transfer between gas and solids.In this work,the particle tracking velocimetry(PTV)method is applied to study the influence of the number of flights on the particle motion in FRDs.The drum,installed with 1,4,8,or 12 rectangular flights,is filled with plastic balls to 15%and operated at various rotating speeds ranging from 10 rpm to 30 rpm.The results show that the number of flights has different effects on the holdup ratio and cascading rate of single flight and active flights.With 8 and 12 flights,the FRD produces a larger and more stable particle ratio of the dilute phase.Moreover,DEM simulations agree with PTV measurements,whereas literature models show significant deviations.
文摘The skirt-to-shell junction weld on coke drums is susceptible to fatigue failure due to severe thermal cyclic stresses. One method to decrease junction stress is to add slots near the top of the skirt, thereby reducing the local stiffness close to the weld. The most common skirt slot design is thin relative to its circumferential spacing. A new slot design, which is significantly wider, is proposed. In this study, thermal-mechanical elastoplastic 3-D finite element models of coke drums are created to analyze the effect of different skirt designs on the stress/strain field near the shell-to-skirt junction weld, as well as any other critical stress locations in the overall skirt design. The results confirm that the inclusion of the conventional slot design effectively reduces stress in the junction weld. However, it has also been found that the critical stress location migrates from the shell-to-skirt junction weld to the slot ends. A method is used to estimate the fatigue life near the critical areas of each skirt slot design. It is found that wider skirt slots provide a significant improvement on fatigue life in the weld and slot area.
基金The research has been supported by the grants from National Natural Science Foundation of China(Grants No.11631011).
文摘LetΩ,with finite Lebesgue measure|Ω|,be a non-empty open subset of R,andΩ=∪∞j-1Ωj,where the open setsΩj are pairwise disjoint and the boundaryГ=■Ωhas Minkowski dimension D∈(0,1).In this paper we study the Dirichlet eigenvalues problem on the domainΩand give the exact second asymptotic term for the eigenvalues,which is related to the Minkowski dimension D.Meanwhile,we give sharp lower bound estimates for Dirichlet eigenvalues for such one-dimensional fractal domains.
文摘Countries from the Global South strengthen ties,showcase innovation and expand cooperation at the eighth CIIE Ahuge crowd gathered at the Ugandan Pavilion in the National Exhibition Hall of the eighth China International Import Expo(CIIE)in Shanghai on the morning of 6 November,as performers danced to the passionate beats of African drums.
