To investigate the fire endurance of wood beams exposed to three-side fire, we conducted bearing capacity tests of two wood beams and experiments of five wood beams exposed to three-side fire. The finite element softw...To investigate the fire endurance of wood beams exposed to three-side fire, we conducted bearing capacity tests of two wood beams and experiments of five wood beams exposed to three-side fire. The finite element software ANSYS was also used to predict the fire endurance of those beams with the indirect order coupling method. It was found that the fire endurance decreases as the load level increases, and the reduction ratio tends to decrease. In the case of a certain load level, the fire endurance is improved if the section size is increased or covered by the fire protection coating. The central deformation increases as the fire duration increases, and the ratio of increase tends to rise. On another note, an increase in the density of wood leads to a rise in the fire endurance of a given beam. From the finite element method (FEM) calculation results, the fire endurance decreases as the load level increases, and the reduction ratio tends to decrease. When the load level is greater than 0.5, the fire endurance is significantly reduced, and it does not change significantly when the load level changes. Lastly, for a load level magnitude below 0.5, the fire endurance and load level are proportional to one another.展开更多
To investigate the charring rate of timber beams exposed to three-side fire, a total of fifteen new and used Douglas-Fir timber beams in four groups exposed to three-side fire were experimentally studied, together wit...To investigate the charring rate of timber beams exposed to three-side fire, a total of fifteen new and used Douglas-Fir timber beams in four groups exposed to three-side fire were experimentally studied, together with the finite element analyses of the temperature distribution in the beam section. The durations of fire exposure were 0 (on a test piece), 10, 15, 20 and 30 min, according to the ISO 834 standard fire curve. The charring depth of each timber beam was calculated by averaging the values at one-third and two-thirds along each cross section to give the charring rate of timber beams. It was found that the timber beam's charring rate reduces as the duration of fire exposure increases and the vertical charring rate is slightly higher than the horizontal one. The areas of beam sections reduce due to charring and the strength and stiffness of the pyrolysis layer near the charring edge decrease owing to the high-temperature. The average horizontal and vertical charring rates are 0.98 and 1.08 mm/min, respectively. To take into account the difference between the test furnace temperature curve and the ISO 834 stand- ard fire curve, some corrections were made for these data to yield the solution for charring rate. With the help of the finite element software ANSYS, the temperature distribution of the wood's cross-section was analyzed. The longer the exposure time is, the greater the effect of density will impose on the distribution of temperature, but the moisture content has no effect.展开更多
功耗攻击是一种通过统计电路的功耗信息得到敏感数据信息的攻击手段。作为电路的重要组成单元,触发器的抗功耗攻击水平与电路的安全性能息息相关,为此提出一种抗功耗攻击型触发器。通过引入“预充电-求值-放电”三阶段逻辑,提出了改进...功耗攻击是一种通过统计电路的功耗信息得到敏感数据信息的攻击手段。作为电路的重要组成单元,触发器的抗功耗攻击水平与电路的安全性能息息相关,为此提出一种抗功耗攻击型触发器。通过引入“预充电-求值-放电”三阶段逻辑,提出了改进型的三阶段动态电流模式逻辑D触发器(improved three-phase dynamic current mode logic-based D flip-flop,TDyCML_FF),避免了因负载电容不均衡引起的电路功耗不恒定等安全问题。同时对三阶段逻辑结构进行了改进,由电路内部节点信号生成放电信号,从而避免通过减缓时钟频率或消除放电信号对其进行攻击,提高了电路的抗功耗攻击性能。通过Hspice仿真实验,并引入归一化能量偏差(NED)和归一化标准偏差(NSD)2个量化参数,将TDyCML_FF感应放大逻辑触发器(SABL_FF)、三阶段双轨预充电逻辑触发器(TDPL_FF)等抗功耗攻击型触发器进行了对比,证明TDyCML_FF具有较高的抗功耗攻击性能。展开更多
In order to study the mechanical properties of damaged reinforced concrete(RC)beams reinforced with ultra-high-performance concrete(UHPC),a four-point bending test was conducted to systematically investigate the influ...In order to study the mechanical properties of damaged reinforced concrete(RC)beams reinforced with ultra-high-performance concrete(UHPC),a four-point bending test was conducted to systematically investigate the influence of factors such as the number of reinforcement surfaces and the degree of damage.The results indicate that single-sided repaired beams have certain advantages in crack resistance performance,but are more disadvantageous in ultimate bearing capacity,with obvious debonding phenomenon before the end of loading.Compared with single-sided reinforcement,the cracking load of the three-sided reinforced beam increased by an average of 1.85 times,the ultimate bearing capacity increased by an average of 177.5%,and a good UHPC-RC combination effect could be formed,which could work synergistically until the end of loading.The degree of pre damage has a significant impact on the crack resistance performance of reinforced beams,while its impact on the ultimate bearing capacity is relatively limited.When the pre splitting width of the RC beam increases from 0.2 mm to 0.4 mm,the ultimate bearing capacity decreases by 28.33%.展开更多
近年来,随着摩尔定律逐渐放缓,晶上系统(System on wafer, SoW)技术作为最热门的“超越摩尔”技术路线之一,已经成为先进封装领域的研究热点。基于晶上系统技术,将传统的毫米波收发前端阵列组件进行三维重构集成,可实现全新的轻薄化毫...近年来,随着摩尔定律逐渐放缓,晶上系统(System on wafer, SoW)技术作为最热门的“超越摩尔”技术路线之一,已经成为先进封装领域的研究热点。基于晶上系统技术,将传统的毫米波收发前端阵列组件进行三维重构集成,可实现全新的轻薄化毫米波晶上阵列,具有“三免”(免连接器、免电缆、免管壳封装)的颠覆性结构。本文针对毫米波晶上阵列的自动化测试需求,创新性提出一种毫米波双面晶圆测试方法,突破了多尺寸双面晶圆可靠固定、双面探针精确对准和自动切换以及扎针强度精确控制和实时调节等关键技术,在此基础上研制出毫米波双面晶圆自动测试平台,解决了毫米波收发前端晶上阵列三维测试的难点,对毫米波晶上系统的测试具有重大参考价值。展开更多
基金Project supported by the National Natural Science Foundation of China (No. 51178115)the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Shanghai Rising-Star Program (Nos. 11QH1402100 and 07QB14031), China
文摘To investigate the fire endurance of wood beams exposed to three-side fire, we conducted bearing capacity tests of two wood beams and experiments of five wood beams exposed to three-side fire. The finite element software ANSYS was also used to predict the fire endurance of those beams with the indirect order coupling method. It was found that the fire endurance decreases as the load level increases, and the reduction ratio tends to decrease. In the case of a certain load level, the fire endurance is improved if the section size is increased or covered by the fire protection coating. The central deformation increases as the fire duration increases, and the ratio of increase tends to rise. On another note, an increase in the density of wood leads to a rise in the fire endurance of a given beam. From the finite element method (FEM) calculation results, the fire endurance decreases as the load level increases, and the reduction ratio tends to decrease. When the load level is greater than 0.5, the fire endurance is significantly reduced, and it does not change significantly when the load level changes. Lastly, for a load level magnitude below 0.5, the fire endurance and load level are proportional to one another.
基金supported by the National Natural Science Foundation of China (Grant No. 51178115)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘To investigate the charring rate of timber beams exposed to three-side fire, a total of fifteen new and used Douglas-Fir timber beams in four groups exposed to three-side fire were experimentally studied, together with the finite element analyses of the temperature distribution in the beam section. The durations of fire exposure were 0 (on a test piece), 10, 15, 20 and 30 min, according to the ISO 834 standard fire curve. The charring depth of each timber beam was calculated by averaging the values at one-third and two-thirds along each cross section to give the charring rate of timber beams. It was found that the timber beam's charring rate reduces as the duration of fire exposure increases and the vertical charring rate is slightly higher than the horizontal one. The areas of beam sections reduce due to charring and the strength and stiffness of the pyrolysis layer near the charring edge decrease owing to the high-temperature. The average horizontal and vertical charring rates are 0.98 and 1.08 mm/min, respectively. To take into account the difference between the test furnace temperature curve and the ISO 834 stand- ard fire curve, some corrections were made for these data to yield the solution for charring rate. With the help of the finite element software ANSYS, the temperature distribution of the wood's cross-section was analyzed. The longer the exposure time is, the greater the effect of density will impose on the distribution of temperature, but the moisture content has no effect.
文摘功耗攻击是一种通过统计电路的功耗信息得到敏感数据信息的攻击手段。作为电路的重要组成单元,触发器的抗功耗攻击水平与电路的安全性能息息相关,为此提出一种抗功耗攻击型触发器。通过引入“预充电-求值-放电”三阶段逻辑,提出了改进型的三阶段动态电流模式逻辑D触发器(improved three-phase dynamic current mode logic-based D flip-flop,TDyCML_FF),避免了因负载电容不均衡引起的电路功耗不恒定等安全问题。同时对三阶段逻辑结构进行了改进,由电路内部节点信号生成放电信号,从而避免通过减缓时钟频率或消除放电信号对其进行攻击,提高了电路的抗功耗攻击性能。通过Hspice仿真实验,并引入归一化能量偏差(NED)和归一化标准偏差(NSD)2个量化参数,将TDyCML_FF感应放大逻辑触发器(SABL_FF)、三阶段双轨预充电逻辑触发器(TDPL_FF)等抗功耗攻击型触发器进行了对比,证明TDyCML_FF具有较高的抗功耗攻击性能。
文摘In order to study the mechanical properties of damaged reinforced concrete(RC)beams reinforced with ultra-high-performance concrete(UHPC),a four-point bending test was conducted to systematically investigate the influence of factors such as the number of reinforcement surfaces and the degree of damage.The results indicate that single-sided repaired beams have certain advantages in crack resistance performance,but are more disadvantageous in ultimate bearing capacity,with obvious debonding phenomenon before the end of loading.Compared with single-sided reinforcement,the cracking load of the three-sided reinforced beam increased by an average of 1.85 times,the ultimate bearing capacity increased by an average of 177.5%,and a good UHPC-RC combination effect could be formed,which could work synergistically until the end of loading.The degree of pre damage has a significant impact on the crack resistance performance of reinforced beams,while its impact on the ultimate bearing capacity is relatively limited.When the pre splitting width of the RC beam increases from 0.2 mm to 0.4 mm,the ultimate bearing capacity decreases by 28.33%.
文摘近年来,随着摩尔定律逐渐放缓,晶上系统(System on wafer, SoW)技术作为最热门的“超越摩尔”技术路线之一,已经成为先进封装领域的研究热点。基于晶上系统技术,将传统的毫米波收发前端阵列组件进行三维重构集成,可实现全新的轻薄化毫米波晶上阵列,具有“三免”(免连接器、免电缆、免管壳封装)的颠覆性结构。本文针对毫米波晶上阵列的自动化测试需求,创新性提出一种毫米波双面晶圆测试方法,突破了多尺寸双面晶圆可靠固定、双面探针精确对准和自动切换以及扎针强度精确控制和实时调节等关键技术,在此基础上研制出毫米波双面晶圆自动测试平台,解决了毫米波收发前端晶上阵列三维测试的难点,对毫米波晶上系统的测试具有重大参考价值。
