Recrystallized grains, less than 200 nm in diameter were observed in heavily shear zones of a high strength low alloy steel and a Ni-based alloy, and Also grain refinement, less than 3 μm in diameter was made in high...Recrystallized grains, less than 200 nm in diameter were observed in heavily shear zones of a high strength low alloy steel and a Ni-based alloy, and Also grain refinement, less than 3 μm in diameter was made in high purity aluminum by ECAE at ambient temperature. The experimental results showed that high strain rate and large deformation could induce dynamic recrystallization.Based on dislocation dynamics and grain orientation change enhanced by plastic deformation,a model for the recrystallization process is developed. The model is used to explain the ultra fine grains which are formed at a temperature still much lower than that for the conventional recrystallization展开更多
To investigate the mechanisms of microwave induced pacemaker cell injuries, Wistar rats and the primary pacemaker cells of newborn Wistar rats were exposed to microwave at average power density of 50 mW/cm2. Slower sp...To investigate the mechanisms of microwave induced pacemaker cell injuries, Wistar rats and the primary pacemaker cells of newborn Wistar rats were exposed to microwave at average power density of 50 mW/cm2. Slower spontaneous beating rate, intercellular Ca2＋ aggregation and cell membrane perforation were detected immediately after the exposure. Moreover, hyperpolarizationactivated cyclic nucleotide-gated cation channel 4 （HCN4） was down-regulated immediately after the exposure and up-regulated at 12 h after the exposure. In the sinoatrial node （SAN） of the rats,展开更多
A 2.4GHz 0.18μm CMOS gain-switched single-end Low Noise Amplifier （LNA） and a passive mixer with no external balun for near-zero-IF （Intermediate Frequency）/RF （Radio Frequency） applications are described. The ...A 2.4GHz 0.18μm CMOS gain-switched single-end Low Noise Amplifier （LNA） and a passive mixer with no external balun for near-zero-IF （Intermediate Frequency）/RF （Radio Frequency） applications are described. The LNA, fabricated in the 0.18μm 1P6M CMOS technology, adopts a gain-switched technique to increase the linearity and enlarge the dynamic range. The mixer is an IQ-based passive topology. Measurements of the CMOS chip are performed on the FR-4 PCB and the input is matched to 50Ω. Combining LNA and mixer, the front-end measured performances in high gain state are： -15dB of Sll, 18.5dB of voltage gain, 4.6dB of noise figure, 15dBm of IIP3, 85dBm to -10dBm dynamic range. The full circuit drains 6mA from a 1.8V supply.展开更多
Er was doped into porous Si by immersing the porous Si sample in a saturated ErCl3,ethanol solution. Sharp and intense 1.54 μm photoluminescence caused by intra-4f-shefl transitions in Er3+ ions was observed up to ro...Er was doped into porous Si by immersing the porous Si sample in a saturated ErCl3,ethanol solution. Sharp and intense 1.54 μm photoluminescence caused by intra-4f-shefl transitions in Er3+ ions was observed up to room temperature. It is shown that the immersing process is valid to dope Er in high concentration in porous Si. Time resolved study of the Er-doped porous Si revealed that the doped Er3+ ions are excited by energy transfer from photo-generated electron-hole pairs in the host. The energy back transfer process from the excited 4f electrons in the Er3+ion to the host is not a dominant factor to quench the Er-related emission in porous Si. Ourresults are well explained by a proposed model in which an intermediate state was introduced.展开更多
Dear Editor,Multiple evanescent white dot syndrome （MEWDS） was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with ...Dear Editor,Multiple evanescent white dot syndrome （MEWDS） was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with fluorescein angiography （FA） and electrophysiology suggested that MEWDS to be a disease in the retinal pigment epithelium （RPE） or outer retina, while recent studies with spectral- domain optical coherence tomography （SD-OCT） suggested it may be an outer retinal disease due to observation of hyperreflective material in outer retina and subtle disruptionsof the ellipsoid zone without RPE disruption.展开更多
As an indication of the Earth＇s mass distribution, the principal moments of inertia （PMOI, i.e., A, B, C） of the Earth are the basic parameters in studies of the global dynamics of the earth, like earth nutation, a...As an indication of the Earth＇s mass distribution, the principal moments of inertia （PMOI, i.e., A, B, C） of the Earth are the basic parameters in studies of the global dynamics of the earth, like earth nutation, and the geophysics. From the aspect of observation, the PMOI can be calculated from the spherical coefficients of observed gravity field. In this paper, the PMOI are calculated directly according to its definition with the figures of the Earth＇s interior derived by a generalized theory of the hydrostatic equilibrium figure of the Earth. We obtain that the angle between the principal axis of the maximum moment of PMOI and the rotational axis is 0.184~, which means that the other two principal axes are very closely in the equatorial plane. Meanwhile, B-A is 1.60 x 10-5 MR2, and the global dynamical flattening （H） is calculated to be 3.29587 ~ 10-3, which is 0.67% different from the latest observation derived value Hobs（3.273795 × 10 ^-3） （Petit and Luzum, 2010）, and this is a significant improvement from the 1.1% difference between the value of H derived from traditional theories of the figure of the Earth and the value of Hobs. It shows that we can calculate the PMOI and H with an appropriate accuracy by a gener- alized theory of the hydrostatic equilibrium figure of the Earth.展开更多
Heat engines based on reciprocating machines remain in demand as energy converters in a variety of industries around the world.The aim of the study was to evaluate the gas-dynamic,consumable and heat exchange characte...Heat engines based on reciprocating machines remain in demand as energy converters in a variety of industries around the world.The aim of the study was to evaluate the gas-dynamic,consumable and heat exchange characteristics of non-stationary air flows in a supply system with transverse profiling of valve channels based on experimental studies.Valve channels with cross sections in the form of a circle,square and triangle were used to control the consumable and heat exchange characteristics of the flows in the supply system of the reciprocatingengine model.The article presents data on changes in local velocity,volumetric airflow and instantaneous heat transfer coefficient of non-stationary airflow in supply systems with different valve channel designs.A spectral analysis of the pulsations of the local heat transfer coefficient was also performed.The Nusselt number was calculated for the studied supply systems.The figured valve channels lead to an increase in the volumetric airflow through the supply systemupto32%comparedwiththe basic configuration.The useof a square valve channel leads to suppression of heat transfer(drop is about 15%)compared to the basic supply system,and the use of a triangular valve channel causes an intensification of heat transfer(growth is about 17.5%).The obtained data can be useful for refining mathematical models,adjusting machine learning algorithms,and improving design methods for supply systems of reciprocating machines to improve their technical,economic,and environmental characteristics.展开更多
以认知诊断和动态评估两者基本的心理计量模型:MLTM for MS和MRMLC相结合作为切入点,提出了基于认知诊断的动态评估方案及数据统计分析方法。为探讨该方案和数据分析方法的可行性,以儿童图形推理能力为例展开实证研究。研究结果显示:(1...以认知诊断和动态评估两者基本的心理计量模型:MLTM for MS和MRMLC相结合作为切入点,提出了基于认知诊断的动态评估方案及数据统计分析方法。为探讨该方案和数据分析方法的可行性,以儿童图形推理能力为例展开实证研究。研究结果显示:(1)基于认知诊断的动态评估方案是可以实现的、其数据分析方法也是可行的;(2)该方案不仅可以测量潜在水平,还可以测量其涉及的认知成分和策略的变化;(3)无论是当前水平还是潜在水平,高年级儿童都更擅长采用较复杂、有效的认知加工成分和策略。展开更多
文摘Recrystallized grains, less than 200 nm in diameter were observed in heavily shear zones of a high strength low alloy steel and a Ni-based alloy, and Also grain refinement, less than 3 μm in diameter was made in high purity aluminum by ECAE at ambient temperature. The experimental results showed that high strain rate and large deformation could induce dynamic recrystallization.Based on dislocation dynamics and grain orientation change enhanced by plastic deformation,a model for the recrystallization process is developed. The model is used to explain the ultra fine grains which are formed at a temperature still much lower than that for the conventional recrystallization
文摘To investigate the mechanisms of microwave induced pacemaker cell injuries, Wistar rats and the primary pacemaker cells of newborn Wistar rats were exposed to microwave at average power density of 50 mW/cm2. Slower spontaneous beating rate, intercellular Ca2＋ aggregation and cell membrane perforation were detected immediately after the exposure. Moreover, hyperpolarizationactivated cyclic nucleotide-gated cation channel 4 （HCN4） was down-regulated immediately after the exposure and up-regulated at 12 h after the exposure. In the sinoatrial node （SAN） of the rats,
文摘A 2.4GHz 0.18μm CMOS gain-switched single-end Low Noise Amplifier （LNA） and a passive mixer with no external balun for near-zero-IF （Intermediate Frequency）/RF （Radio Frequency） applications are described. The LNA, fabricated in the 0.18μm 1P6M CMOS technology, adopts a gain-switched technique to increase the linearity and enlarge the dynamic range. The mixer is an IQ-based passive topology. Measurements of the CMOS chip are performed on the FR-4 PCB and the input is matched to 50Ω. Combining LNA and mixer, the front-end measured performances in high gain state are： -15dB of Sll, 18.5dB of voltage gain, 4.6dB of noise figure, 15dBm of IIP3, 85dBm to -10dBm dynamic range. The full circuit drains 6mA from a 1.8V supply.
文摘Er was doped into porous Si by immersing the porous Si sample in a saturated ErCl3,ethanol solution. Sharp and intense 1.54 μm photoluminescence caused by intra-4f-shefl transitions in Er3+ ions was observed up to room temperature. It is shown that the immersing process is valid to dope Er in high concentration in porous Si. Time resolved study of the Er-doped porous Si revealed that the doped Er3+ ions are excited by energy transfer from photo-generated electron-hole pairs in the host. The energy back transfer process from the excited 4f electrons in the Er3+ion to the host is not a dominant factor to quench the Er-related emission in porous Si. Ourresults are well explained by a proposed model in which an intermediate state was introduced.
文摘Dear Editor,Multiple evanescent white dot syndrome （MEWDS） was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with fluorescein angiography （FA） and electrophysiology suggested that MEWDS to be a disease in the retinal pigment epithelium （RPE） or outer retina, while recent studies with spectral- domain optical coherence tomography （SD-OCT） suggested it may be an outer retinal disease due to observation of hyperreflective material in outer retina and subtle disruptionsof the ellipsoid zone without RPE disruption.
文摘As an indication of the Earth＇s mass distribution, the principal moments of inertia （PMOI, i.e., A, B, C） of the Earth are the basic parameters in studies of the global dynamics of the earth, like earth nutation, and the geophysics. From the aspect of observation, the PMOI can be calculated from the spherical coefficients of observed gravity field. In this paper, the PMOI are calculated directly according to its definition with the figures of the Earth＇s interior derived by a generalized theory of the hydrostatic equilibrium figure of the Earth. We obtain that the angle between the principal axis of the maximum moment of PMOI and the rotational axis is 0.184~, which means that the other two principal axes are very closely in the equatorial plane. Meanwhile, B-A is 1.60 x 10-5 MR2, and the global dynamical flattening （H） is calculated to be 3.29587 ~ 10-3, which is 0.67% different from the latest observation derived value Hobs（3.273795 × 10 ^-3） （Petit and Luzum, 2010）, and this is a significant improvement from the 1.1% difference between the value of H derived from traditional theories of the figure of the Earth and the value of Hobs. It shows that we can calculate the PMOI and H with an appropriate accuracy by a gener- alized theory of the hydrostatic equilibrium figure of the Earth.
基金supported by the Russian Science Foundation(Grant No.23-29-00022).
文摘Heat engines based on reciprocating machines remain in demand as energy converters in a variety of industries around the world.The aim of the study was to evaluate the gas-dynamic,consumable and heat exchange characteristics of non-stationary air flows in a supply system with transverse profiling of valve channels based on experimental studies.Valve channels with cross sections in the form of a circle,square and triangle were used to control the consumable and heat exchange characteristics of the flows in the supply system of the reciprocatingengine model.The article presents data on changes in local velocity,volumetric airflow and instantaneous heat transfer coefficient of non-stationary airflow in supply systems with different valve channel designs.A spectral analysis of the pulsations of the local heat transfer coefficient was also performed.The Nusselt number was calculated for the studied supply systems.The figured valve channels lead to an increase in the volumetric airflow through the supply systemupto32%comparedwiththe basic configuration.The useof a square valve channel leads to suppression of heat transfer(drop is about 15%)compared to the basic supply system,and the use of a triangular valve channel causes an intensification of heat transfer(growth is about 17.5%).The obtained data can be useful for refining mathematical models,adjusting machine learning algorithms,and improving design methods for supply systems of reciprocating machines to improve their technical,economic,and environmental characteristics.
文摘以认知诊断和动态评估两者基本的心理计量模型:MLTM for MS和MRMLC相结合作为切入点,提出了基于认知诊断的动态评估方案及数据统计分析方法。为探讨该方案和数据分析方法的可行性,以儿童图形推理能力为例展开实证研究。研究结果显示:(1)基于认知诊断的动态评估方案是可以实现的、其数据分析方法也是可行的;(2)该方案不仅可以测量潜在水平,还可以测量其涉及的认知成分和策略的变化;(3)无论是当前水平还是潜在水平,高年级儿童都更擅长采用较复杂、有效的认知加工成分和策略。
