Based on the theory of continuum mechanics of multi-pbase media, a mathematical model and non-linear FEM equation of the coupling instability problem of solid-fluid biphase media for coal-methane outburst under finite...Based on the theory of continuum mechanics of multi-pbase media, a mathematical model and non-linear FEM equation of the coupling instability problem of solid-fluid biphase media for coal-methane outburst under finite deformation are established. The critical conditions of the surface instability are presented as the singularity of the total stiffness matrices of the coal body for coal-methaue outburst. That means the deformtion or the coal body emerges bifurcatiou phenomena. The numerical simulation of a typical outburst is made.展开更多
The mechanical effects of bolt-mesh-anchor coupling support in deep tunnels were studied by using a numerical method, based on deep tunnel coupling supporting techniques and non-linear deformation mechanical theory of...The mechanical effects of bolt-mesh-anchor coupling support in deep tunnels were studied by using a numerical method, based on deep tunnel coupling supporting techniques and non-linear deformation mechanical theory of rock mass at great depths.It is shown that the potential of a rigid bolt support can be efficiently activated through the coupling effect between a bolt-net support and the surrounding rock.It is found that the accumulated plastic energy in the surrounding rock can be sufficiently transformed by the coupling effect of a bolt-mesh-tray support.The strength of the surrounding rock mass can be mobilized to control the deforma-tion of the surrounding rock by a pre-stress and time-space effect of the anchor support.The high stress transformation effect can be realized by the mechanical coupling effect of the bolt-mesh-anchor support, whereby the force of the support and deformation of the surrounding rock tends to become uniform, leading to a sustained stability of the tunnel.展开更多
Combining vacuum preloading technology and electroosmosis can improve the treatment effect of soft soil foundation by utilizing the advantages of both methods.Many studies indicate that the soil electrical potential i...Combining vacuum preloading technology and electroosmosis can improve the treatment effect of soft soil foundation by utilizing the advantages of both methods.Many studies indicate that the soil electrical potential is non-linearly distributed in the treatment process by the combined method.However,in the previous theoretical study,the non-linear-distribution impacts of soil’s electrical potential on soft soil foundation treatment have not been considered.It is always assumed to be linear distribution,which is different from the experimental results.In this paper,the coupling consolidation model of this technology under the two-dimensional plane strain condition is initially established;and the well resistance effect,the vacuum load decreasing along the soil depth and the non-linear variation of electrical potential in the soil are considered.Then,the analytical solutions of the average excess pore water pressure and soil’s consolidation degree in the anode affected area are acquired based on the soil’s electrical potential distribution.Finally,the rationality of the analytical solution is testified by conducting an experimental model test,which proves the scientificity of the analytical solution.The analytical solution is adopted to better predict the dissipation of excess pore water pressure and soil consolidation degree when using the combined technology.This study can provide a reference with more accuracy for the engineering practices of this combined technology in the future.展开更多
Electroceuticals are medical devices that employ electric signals to alter the activity of specific nerve fibers to achieve therapeutic effects. The rapid growth of RF microelectronics has resulted in the development ...Electroceuticals are medical devices that employ electric signals to alter the activity of specific nerve fibers to achieve therapeutic effects. The rapid growth of RF microelectronics has resulted in the development of very small, portable, and inexpensive shortwave and microwave radio frequency (RF) amplifiers, raising the possibility of utilizing these new RF technologies to develop non-contact electroceutical devices. However, the bio-electromagnetics literature suggests that beyond 10 MHz, RF fields cannot influence biological tissue, beyond simple heating, because effective demodulation mechanisms at these frequencies do not exist in the body. However, RF amplifiers operating at or near saturation have non-linear interactions with complex loads, and if body tissue creates a complex loading condition, the opportunity exists for the coupled system to produce non-linear effects, that is, the equivalent of demodulation may occur. Correspondingly, exposure of tissue to pulsed RF energy could result in the creation of low frequency demodulation components capable of influencing tissue activity. Here, we develop a one-dimen- sional, numerical simulation to investigate the complex loading conditions under which such demodulation could arise. Applying these results in a physical prototype device, we show that up to7.5% demodulation can be obtained for a 40 MHz RF field pulsed at 1 KHz. Implications for this research include the possibility of developing wearable, electromagnetic electroceutical de- vices.展开更多
变压器是重要的变电站设备,然而在地震中会遭受各种形式的破坏。由220 k V套管和变压器组成的体系为试验对象,进行变压器–套管体系振动台试验,测得满足IEEE 693需求反应谱的地震波激励下的体系关键位置的地震响应;以El Centro波激励下...变压器是重要的变电站设备,然而在地震中会遭受各种形式的破坏。由220 k V套管和变压器组成的体系为试验对象,进行变压器–套管体系振动台试验,测得满足IEEE 693需求反应谱的地震波激励下的体系关键位置的地震响应;以El Centro波激励下体系的地震响应为例,分析加速度和位移响应沿体系高度的分布情况;最后探讨变压器升高座和套管的地震响应机理。得到体系基本动力特性,且在峰值为0.3 g地震波激励下套管法兰出现渗油、垫片松动震害。分析表明:当套管法兰抗弯刚度较大时,变压器箱体箱壁的面外刚度不足引起套管动力响应放大和升高座摆动,套管振动与升高座摆动耦合在一起,两者绕升高座根部整体摆动;然而套管法兰刚度变小时,套管绕其根部法兰开始摆动,套管振动与升高座摆动耦合作用变弱。展开更多
为研究地震作用下硬管母线连接特高压电气设备之间的动力相互作用,进行了由硬管母线连接的1 000 k V避雷器和电容电压式互感器（CVT）组成的互连耦合结构体系的振动台试验。通过白噪声扫频和抗震试验,测定了设备频率以及关键部位的位移...为研究地震作用下硬管母线连接特高压电气设备之间的动力相互作用,进行了由硬管母线连接的1 000 k V避雷器和电容电压式互感器（CVT）组成的互连耦合结构体系的振动台试验。通过白噪声扫频和抗震试验,测定了设备频率以及关键部位的位移、应变和加速度响应。对比分析等效单体设备与互连耦合结构的地震响应,获得了硬管母线对电气设备地震响应的影响规律。结果表明：与等效单体设备相比,互连耦合结构的设备频率、位移和应变响应均有所降低,可采用在单体设备顶端施加配重的方式来等效简化互连耦合结构;由于硬管母线和滑动金具阻尼耗能的影响,高频互感器设备的地震响应降幅较大,其频率和应变响应的降幅均为21%。互连耦合结构在双向激励下的设备地震响应与单向激励时相比有所放大,放大倍数在1.19~1.22之间。展开更多
文摘Based on the theory of continuum mechanics of multi-pbase media, a mathematical model and non-linear FEM equation of the coupling instability problem of solid-fluid biphase media for coal-methane outburst under finite deformation are established. The critical conditions of the surface instability are presented as the singularity of the total stiffness matrices of the coal body for coal-methaue outburst. That means the deformtion or the coal body emerges bifurcatiou phenomena. The numerical simulation of a typical outburst is made.
基金Projects 2006CB202200 supported by the National Basic Research Program of ChinaNCET07-0800 by the Program for New Century Excellent Talents in Universities
文摘The mechanical effects of bolt-mesh-anchor coupling support in deep tunnels were studied by using a numerical method, based on deep tunnel coupling supporting techniques and non-linear deformation mechanical theory of rock mass at great depths.It is shown that the potential of a rigid bolt support can be efficiently activated through the coupling effect between a bolt-net support and the surrounding rock.It is found that the accumulated plastic energy in the surrounding rock can be sufficiently transformed by the coupling effect of a bolt-mesh-tray support.The strength of the surrounding rock mass can be mobilized to control the deforma-tion of the surrounding rock by a pre-stress and time-space effect of the anchor support.The high stress transformation effect can be realized by the mechanical coupling effect of the bolt-mesh-anchor support, whereby the force of the support and deformation of the surrounding rock tends to become uniform, leading to a sustained stability of the tunnel.
基金Project(51979087)supported by the National Natural Science Foundation of ChinaProject(BK20180776)supported by the Jiangsu Natural Science Foundation,ChinaProject(202006710002)supported by the China Scholarship Council。
文摘Combining vacuum preloading technology and electroosmosis can improve the treatment effect of soft soil foundation by utilizing the advantages of both methods.Many studies indicate that the soil electrical potential is non-linearly distributed in the treatment process by the combined method.However,in the previous theoretical study,the non-linear-distribution impacts of soil’s electrical potential on soft soil foundation treatment have not been considered.It is always assumed to be linear distribution,which is different from the experimental results.In this paper,the coupling consolidation model of this technology under the two-dimensional plane strain condition is initially established;and the well resistance effect,the vacuum load decreasing along the soil depth and the non-linear variation of electrical potential in the soil are considered.Then,the analytical solutions of the average excess pore water pressure and soil’s consolidation degree in the anode affected area are acquired based on the soil’s electrical potential distribution.Finally,the rationality of the analytical solution is testified by conducting an experimental model test,which proves the scientificity of the analytical solution.The analytical solution is adopted to better predict the dissipation of excess pore water pressure and soil consolidation degree when using the combined technology.This study can provide a reference with more accuracy for the engineering practices of this combined technology in the future.
文摘Electroceuticals are medical devices that employ electric signals to alter the activity of specific nerve fibers to achieve therapeutic effects. The rapid growth of RF microelectronics has resulted in the development of very small, portable, and inexpensive shortwave and microwave radio frequency (RF) amplifiers, raising the possibility of utilizing these new RF technologies to develop non-contact electroceutical devices. However, the bio-electromagnetics literature suggests that beyond 10 MHz, RF fields cannot influence biological tissue, beyond simple heating, because effective demodulation mechanisms at these frequencies do not exist in the body. However, RF amplifiers operating at or near saturation have non-linear interactions with complex loads, and if body tissue creates a complex loading condition, the opportunity exists for the coupled system to produce non-linear effects, that is, the equivalent of demodulation may occur. Correspondingly, exposure of tissue to pulsed RF energy could result in the creation of low frequency demodulation components capable of influencing tissue activity. Here, we develop a one-dimen- sional, numerical simulation to investigate the complex loading conditions under which such demodulation could arise. Applying these results in a physical prototype device, we show that up to7.5% demodulation can be obtained for a 40 MHz RF field pulsed at 1 KHz. Implications for this research include the possibility of developing wearable, electromagnetic electroceutical de- vices.
文摘为研究地震作用下硬管母线连接特高压电气设备之间的动力相互作用,进行了由硬管母线连接的1 000 k V避雷器和电容电压式互感器（CVT）组成的互连耦合结构体系的振动台试验。通过白噪声扫频和抗震试验,测定了设备频率以及关键部位的位移、应变和加速度响应。对比分析等效单体设备与互连耦合结构的地震响应,获得了硬管母线对电气设备地震响应的影响规律。结果表明：与等效单体设备相比,互连耦合结构的设备频率、位移和应变响应均有所降低,可采用在单体设备顶端施加配重的方式来等效简化互连耦合结构;由于硬管母线和滑动金具阻尼耗能的影响,高频互感器设备的地震响应降幅较大,其频率和应变响应的降幅均为21%。互连耦合结构在双向激励下的设备地震响应与单向激励时相比有所放大,放大倍数在1.19~1.22之间。
