The effects of non-magnetic atom vacancy on structural, martensitic phase transitions and the corresponding magnetocMoric effect in MnCoGel-x alloys are investigated using x-ray diffraction and magnetic measurements. ...The effects of non-magnetic atom vacancy on structural, martensitic phase transitions and the corresponding magnetocMoric effect in MnCoGel-x alloys are investigated using x-ray diffraction and magnetic measurements. The introduction of non-magnetic atom vacancy leads to the decrease of the martensitic transition temperature and realizes a temperature window where magnetic and martensitic phase transitions can be tuned together. Moreover, the giant magnetocaloric effect accompanied with the coupled magnetic-structural transition is ob- tained. It is observed that the peak values of magnetic entropy change of MnCoGeo.97 are about -13.9, -35.1 and -47.4J.kg-1K-1 for △H = 2, 5, 7T, respectively.展开更多
调谐黏滞质量阻尼器(Tuned Viscous Mass Damper,TVMD)是一种有效的被动惯容减震装置,本文针对地震作用下建筑结构TVMD阻尼比增效效应与优化设计展开研究。将TVMD对结构自身阻尼耗能功率的控制效果归纳为TVMD等效附加阻尼比,并基于随机...调谐黏滞质量阻尼器(Tuned Viscous Mass Damper,TVMD)是一种有效的被动惯容减震装置,本文针对地震作用下建筑结构TVMD阻尼比增效效应与优化设计展开研究。将TVMD对结构自身阻尼耗能功率的控制效果归纳为TVMD等效附加阻尼比,并基于随机振动理论推导了等效附加阻尼比的理论表达式。为了使TVMD更具实际应用价值,TVMD理论上应取得比同阻尼系数的黏滞阻尼器(VD)更大的等效附加阻尼比,这一现象定义为TVMD阻尼比增效效应,并定义了阻尼比增效系数来量化评估阻尼比增效效应。将等效附加阻尼比和阻尼比增效系数均作为优化目标,提出了TVMD最优设计参数理论解。参数分析结果表明,本文解具有良好的稳定性和适用性,为了更高效地发挥阻尼比增效效应,推荐TVMD质量比不超过0.3或阻尼比不超过0.1。以某七层标准钢框架结构作为工程算例展示了TVMD设计流程,并验证了本文解的有效性和优越性。算例分析结果表明,使用本文解设计TVMD能显著放大其阻尼元件变形,表现出了理想的阻尼比增效效应。与传统解相比,本文解还具有另一个明显优势,即保证TVMD的减震效果优于同阻尼系数的VD,不存在减震效率问题。展开更多
We investigated the structural and optical properties of amorphous-SiGe thin films synthesized via a low-cost, high-growth rate deposition method. Films were formed by e-beam evaporation of mixed pellets of Si and Ge....We investigated the structural and optical properties of amorphous-SiGe thin films synthesized via a low-cost, high-growth rate deposition method. Films were formed by e-beam evaporation of mixed pellets of Si and Ge. Film composition was varied by changing the weight ratio of Si and Ge pellets mixture. Films were amorphous with a composition uniform. Ge-rich films are in tensile stress, while Si-rich films are in compressive stress. As the Ge fraction increases (from 22 at.% to 94 at.%), the optical bandgap decreases (from 1.7 eV to 0.9 eV) and the photosensitivity of the films extends into IR band of solar spectrum. By changing the weighted ratio of the evaporation source mixture, the bandgap and optical sensitivity of a-SiGe films can be easily tuned. Our studies prove that a-SiGe films are a tunable absorber. This can be used for photo-detector, photovoltaic and microelectronic applications to extend the spectral response.展开更多
We present the fabrication and testing of a silicon carbide(SiC)balanced mass double-ended tuning fork that survives harsh environments without compromising the device strain sensitivity and resolution bandwidth.The d...We present the fabrication and testing of a silicon carbide(SiC)balanced mass double-ended tuning fork that survives harsh environments without compromising the device strain sensitivity and resolution bandwidth.The device features a material stack that survives corrosive environments and enables high-temperature operation.To perform high-temperature testing,a specialized setup was constructed that allows the tuning fork to be characterized using traditional silicon electronics.The tuning fork has been operated at 600 ℃ in the presence of dry steam for short durations.This tuning fork has also been tested to 64 000 G using a hard-launch,soft-catch shock implemented with a light gas gun.However,the device still has a strain sensitivity of 66 Hz/με and strain resolution of 0.045 με in a 10 kHz bandwidth.As such,this balanced-mass double-ended tuning fork can be used to create a variety of different sensors including strain gauges,accelerometers,gyroscopes,and pressure transducers.Given the adaptable fabrication process flow,this device could be useful to micro-electro-mechanical systems(MEMS) designers creating sensors for a variety of different applications.展开更多
The beam-beam effects in a hadron collider with an unprecedented energy scale were studied.These effects are strongly related to the attainable luminosity of the collider.Long-range interactions were identified as the...The beam-beam effects in a hadron collider with an unprecedented energy scale were studied.These effects are strongly related to the attainable luminosity of the collider.Long-range interactions were identified as the major factor limiting the dynamic aperture,which is strongly dependent on the crossing angle,β*,and bunch population.Different mitigation methods of the beam-beam effects were addressed,with a focus on the compensation of long-range interactions by electric curren wires.The CEPC-SPPC project is a two-stage large circular collider,with a first-stage circular electron-positron collider(CEPC)and a second-stage super proton-proton collider(SPPC).The design of the SPPC aims to achieve a center-of-mass energy of 75 TeV and peak luminosity of approximately 1×10^(35) cm^(-2)s^(-1).We studied the beam-beam effects in the SPPC and tested the effectiveness of the mitigation methods.We found that with compensation using electric current wires,the dynamic aperture is at an acceptable level.Moreover,considering the significant emittance damping in this future proton-proton collider the beam-beam effects and compensation are more complicated and are studied using long-term tracking.It was found that with a smaller emittance,the head-on interactions with a crossing angle become more prominent in reducing the beam stability,and combined head-on and long-range compensation is needed to improve the beam quality.When the reduction in population owing to burnoff was included,it was found that the coupling between the transverse and longitudinal planes at smaller emittance is the main driving source of the instabilities.Thus,crab cavities and emittance control are also necessary than just the compensation of the long-range interactions to improve the beam stability.This study serves as an example for studying the beam-beam effects in future proton-proton colliders.展开更多
砂岩油气储层在地震剖面上一般表现为“亮点”,但钻探发现四川盆地中江气田的一些砂岩储层在地震剖面上表现为“暗点”,不易识别。这里依据钻测井资料,采用地震正演模拟方法分析了这些储层地震响应表现为“暗点”的机制,认为是Ⅱb类AVO(...砂岩油气储层在地震剖面上一般表现为“亮点”,但钻探发现四川盆地中江气田的一些砂岩储层在地震剖面上表现为“暗点”,不易识别。这里依据钻测井资料,采用地震正演模拟方法分析了这些储层地震响应表现为“暗点”的机制,认为是Ⅱb类AVO(Amplitude variation with offset)响应砂岩在特定厚度的薄层调谐作用下,在叠前道集中发生了极性反转,从而使得原本在叠后剖面上应为较“亮点”的反射变成了“暗点”。针对这种储层隐蔽机制,采用高分辨处理与AVO分析相结合的方法,成功识别出了消隐的河道砂储层,为“暗点”型薄砂岩储层的识别提供了可参考的成功范例。展开更多
采用半波长交流输电方式时,当线路的自然长度不足半个波长时,需要对电气波长进行人工调谐。基于传输线理论模型的电容调谐网络,要求调谐电容必须均匀分布在整个输电线路上,根据半波长输电条件(即线路的电气长度等于1个工频半波)推导出...采用半波长交流输电方式时,当线路的自然长度不足半个波长时,需要对电气波长进行人工调谐。基于传输线理论模型的电容调谐网络,要求调谐电容必须均匀分布在整个输电线路上,根据半波长输电条件(即线路的电气长度等于1个工频半波)推导出调谐电容值计算公式,并结合某1 000 k V交流输电线路参数,分别仿真不同调谐电容数时的调谐效果。结果表明,并非补偿点数量越多,调谐效果就越好。当调谐电容数达到8时,调谐效果趋于稳定,即满足了半波长输电要求,同时使得调谐电容数目最少。展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11504222
文摘The effects of non-magnetic atom vacancy on structural, martensitic phase transitions and the corresponding magnetocMoric effect in MnCoGel-x alloys are investigated using x-ray diffraction and magnetic measurements. The introduction of non-magnetic atom vacancy leads to the decrease of the martensitic transition temperature and realizes a temperature window where magnetic and martensitic phase transitions can be tuned together. Moreover, the giant magnetocaloric effect accompanied with the coupled magnetic-structural transition is ob- tained. It is observed that the peak values of magnetic entropy change of MnCoGeo.97 are about -13.9, -35.1 and -47.4J.kg-1K-1 for △H = 2, 5, 7T, respectively.
文摘调谐黏滞质量阻尼器(Tuned Viscous Mass Damper,TVMD)是一种有效的被动惯容减震装置,本文针对地震作用下建筑结构TVMD阻尼比增效效应与优化设计展开研究。将TVMD对结构自身阻尼耗能功率的控制效果归纳为TVMD等效附加阻尼比,并基于随机振动理论推导了等效附加阻尼比的理论表达式。为了使TVMD更具实际应用价值,TVMD理论上应取得比同阻尼系数的黏滞阻尼器(VD)更大的等效附加阻尼比,这一现象定义为TVMD阻尼比增效效应,并定义了阻尼比增效系数来量化评估阻尼比增效效应。将等效附加阻尼比和阻尼比增效系数均作为优化目标,提出了TVMD最优设计参数理论解。参数分析结果表明,本文解具有良好的稳定性和适用性,为了更高效地发挥阻尼比增效效应,推荐TVMD质量比不超过0.3或阻尼比不超过0.1。以某七层标准钢框架结构作为工程算例展示了TVMD设计流程,并验证了本文解的有效性和优越性。算例分析结果表明,使用本文解设计TVMD能显著放大其阻尼元件变形,表现出了理想的阻尼比增效效应。与传统解相比,本文解还具有另一个明显优势,即保证TVMD的减震效果优于同阻尼系数的VD,不存在减震效率问题。
文摘We investigated the structural and optical properties of amorphous-SiGe thin films synthesized via a low-cost, high-growth rate deposition method. Films were formed by e-beam evaporation of mixed pellets of Si and Ge. Film composition was varied by changing the weight ratio of Si and Ge pellets mixture. Films were amorphous with a composition uniform. Ge-rich films are in tensile stress, while Si-rich films are in compressive stress. As the Ge fraction increases (from 22 at.% to 94 at.%), the optical bandgap decreases (from 1.7 eV to 0.9 eV) and the photosensitivity of the films extends into IR band of solar spectrum. By changing the weighted ratio of the evaporation source mixture, the bandgap and optical sensitivity of a-SiGe films can be easily tuned. Our studies prove that a-SiGe films are a tunable absorber. This can be used for photo-detector, photovoltaic and microelectronic applications to extend the spectral response.
文摘We present the fabrication and testing of a silicon carbide(SiC)balanced mass double-ended tuning fork that survives harsh environments without compromising the device strain sensitivity and resolution bandwidth.The device features a material stack that survives corrosive environments and enables high-temperature operation.To perform high-temperature testing,a specialized setup was constructed that allows the tuning fork to be characterized using traditional silicon electronics.The tuning fork has been operated at 600 ℃ in the presence of dry steam for short durations.This tuning fork has also been tested to 64 000 G using a hard-launch,soft-catch shock implemented with a light gas gun.However,the device still has a strain sensitivity of 66 Hz/με and strain resolution of 0.045 με in a 10 kHz bandwidth.As such,this balanced-mass double-ended tuning fork can be used to create a variety of different sensors including strain gauges,accelerometers,gyroscopes,and pressure transducers.Given the adaptable fabrication process flow,this device could be useful to micro-electro-mechanical systems(MEMS) designers creating sensors for a variety of different applications.
基金supported by the National Natural Science Foundation of China (Nos. 11575214, 11527811, and 11805218)the Fermi Research Alliance+1 种基金LLCunder contract no. DE-AC02-07CH11359with the U.S. Department of Energy。
文摘The beam-beam effects in a hadron collider with an unprecedented energy scale were studied.These effects are strongly related to the attainable luminosity of the collider.Long-range interactions were identified as the major factor limiting the dynamic aperture,which is strongly dependent on the crossing angle,β*,and bunch population.Different mitigation methods of the beam-beam effects were addressed,with a focus on the compensation of long-range interactions by electric curren wires.The CEPC-SPPC project is a two-stage large circular collider,with a first-stage circular electron-positron collider(CEPC)and a second-stage super proton-proton collider(SPPC).The design of the SPPC aims to achieve a center-of-mass energy of 75 TeV and peak luminosity of approximately 1×10^(35) cm^(-2)s^(-1).We studied the beam-beam effects in the SPPC and tested the effectiveness of the mitigation methods.We found that with compensation using electric current wires,the dynamic aperture is at an acceptable level.Moreover,considering the significant emittance damping in this future proton-proton collider the beam-beam effects and compensation are more complicated and are studied using long-term tracking.It was found that with a smaller emittance,the head-on interactions with a crossing angle become more prominent in reducing the beam stability,and combined head-on and long-range compensation is needed to improve the beam quality.When the reduction in population owing to burnoff was included,it was found that the coupling between the transverse and longitudinal planes at smaller emittance is the main driving source of the instabilities.Thus,crab cavities and emittance control are also necessary than just the compensation of the long-range interactions to improve the beam stability.This study serves as an example for studying the beam-beam effects in future proton-proton colliders.
文摘砂岩油气储层在地震剖面上一般表现为“亮点”,但钻探发现四川盆地中江气田的一些砂岩储层在地震剖面上表现为“暗点”,不易识别。这里依据钻测井资料,采用地震正演模拟方法分析了这些储层地震响应表现为“暗点”的机制,认为是Ⅱb类AVO(Amplitude variation with offset)响应砂岩在特定厚度的薄层调谐作用下,在叠前道集中发生了极性反转,从而使得原本在叠后剖面上应为较“亮点”的反射变成了“暗点”。针对这种储层隐蔽机制,采用高分辨处理与AVO分析相结合的方法,成功识别出了消隐的河道砂储层,为“暗点”型薄砂岩储层的识别提供了可参考的成功范例。
文摘采用半波长交流输电方式时,当线路的自然长度不足半个波长时,需要对电气波长进行人工调谐。基于传输线理论模型的电容调谐网络,要求调谐电容必须均匀分布在整个输电线路上,根据半波长输电条件(即线路的电气长度等于1个工频半波)推导出调谐电容值计算公式,并结合某1 000 k V交流输电线路参数,分别仿真不同调谐电容数时的调谐效果。结果表明,并非补偿点数量越多,调谐效果就越好。当调谐电容数达到8时,调谐效果趋于稳定,即满足了半波长输电要求,同时使得调谐电容数目最少。
