Si-PIN photodetectors having features such as low cost,small size,low weight,low voltage,and low power consumption are widely used as radiation detectors in electronic personal dosimeters(EPDs).The technical parameter...Si-PIN photodetectors having features such as low cost,small size,low weight,low voltage,and low power consumption are widely used as radiation detectors in electronic personal dosimeters(EPDs).The technical parameters of EPDs based on the Si-PIN photodetectors include photon energy response(PER),angular response,inherent error,and dose rate linearity.Among them,PER is a key parameter for evaluation of EPD measurement accuracy.At present,owing to the limitations of volume,power consumption,and EPD cost,the PER is usually corrected by a combination of single-channel counting techniques and filtering material methods.However,the above-mentioned methods have problems such as poor PER and low measurement accuracy.To solve such problems,in this study,a 1024-channel spectrometry system using a Si-PIN photodetector was developed and fullspectrum measurement in the reference radiation fields was conducted for radiation protection.The measurement results using the few-channel spectroscopy dose method showed that the PER could be controlled within±14%and±2%under the conditions of two and three energy intervals,respectively,with different channel numbers.The PER measured at 0°angle of radiation incidence meets the-29%to+67%requirements of IEC 61526:2010.Meanwhile,the channel number and counts-to-dose conversion factors formed in the experiment can be integrated into an EPD.展开更多
Effective atomic numbers for photon energy absorption(ZPEA_(eff)) and their corresponding electron numbers (NPEA_(eff)), and effective macroscopic removal cross sections of fast neutrons(RR) were calculated for 27 dif...Effective atomic numbers for photon energy absorption(ZPEA_(eff)) and their corresponding electron numbers (NPEA_(eff)), and effective macroscopic removal cross sections of fast neutrons(RR) were calculated for 27 different types of three-dimensional dosimeters, four types of phantom materials, and water. The values of ZPEA_(eff) and NPEA_(eff) were obtained using the direct method for energies ranging from 10 keV to 20 MeV. Results are presented relative to water, for direct comparison over the range of examined energies. The effect of monomers that are used in polymer gel dosimeters on the water equivalence is discussed. The relation between Σ_R and hydrogen content was studied. Micelle gel dosimeters are highly promising because our results demonstrate perfect matching between the effective atomic number, electron density number, and fast neutron attenuation coefficient of water.展开更多
A theory of （4＋1）-dimensional gravity is developed on the basis of the teleparallel theory equivalent to general relativity. The fundamental gravitational field variables are the five-dimensional vector fields （pe...A theory of （4＋1）-dimensional gravity is developed on the basis of the teleparallel theory equivalent to general relativity. The fundamental gravitational field variables are the five-dimensional vector fields （pentad）, defined globally on a manifold M, and gravity is attributed to the torsion. The Lagrangian density is quadratic in the torsion tensor. We then give the exact five-dimensional solution. The solution is a generalization of the familiar Schwarzschild and Kerr solutions of the four-dimensional teleparallel equivalent of general relativity. We also use the definition of the gravitational energy to calculate the energy and the spatial momentum.展开更多
A perfect fluid with self-similarity of the second kind is studied within the framework of the teleparallel equivalent of general relativity （TEGR）. A spacetime which is not asymptotically fiat is derived. The energ...A perfect fluid with self-similarity of the second kind is studied within the framework of the teleparallel equivalent of general relativity （TEGR）. A spacetime which is not asymptotically fiat is derived. The energy conditions of this spacetime are studied. It is shown that after some time the strong energy condition is not enough to satisfy showing a transition from standard matter to dark energy. The singularities of this solution are discussed.展开更多
We derive two new retarded solutions in the teleparallel theory equivalent to general relativity （TEGR）. One of these solutions gives a divergent energy. Therefore, we use the regularized expression of the gravitati...We derive two new retarded solutions in the teleparallel theory equivalent to general relativity （TEGR）. One of these solutions gives a divergent energy. Therefore, we use the regularized expression of the gravitational energymomentum tensor, which is a coordinate dependent. A detailed analysis of the loss of the mass of Bondi space-time is carried out using the flux of the gravitational energy-momentum.展开更多
The energy--momentum tensor, which is coordinate-independent, is used to calculate energy, momentum and angular momentum of two different tetrad fields. Although, the two tetrad fields reproduce the same space--time t...The energy--momentum tensor, which is coordinate-independent, is used to calculate energy, momentum and angular momentum of two different tetrad fields. Although, the two tetrad fields reproduce the same space--time their energies are different. Therefore, a regularized expression of the gravitational energy--momentum tensor of the teleparallel equivalent of general relativity （TEGR）, is used to make the energies of the two tetrad fields equal. The definition of the gravitational energy--momentum is used to investigate the energy within the external event horizon. The components of angular momentum associated with these space--times are calculated. In spite of using a static space--time, we get a non-zero component of angular momentum! Therefore, we derive the Killing vectors associated with these space--times using the definition of the Lie derivative of a second rank tensor in the framework of the TEGR to make the picture more clear.展开更多
We apply the energy momentum and angular momentum tensor to a tetrad field, with two unknown functions of radial coordinate, in the framework of a teleparallel equivalent of general relativity （TEGR）. The definition...We apply the energy momentum and angular momentum tensor to a tetrad field, with two unknown functions of radial coordinate, in the framework of a teleparallel equivalent of general relativity （TEGR）. The definition of the gravitational energy is used to investigate the energy within the external event horizon of the dyadosphere region for the Reissner-NordstrSm black hole. We also calculate the spatial momentum and angular momentum.展开更多
对于均匀、各向同性、幂律硬化的金属材料,以锥形端头小冲杆对试样圆面中心法向施加压载荷,提出基于能量密度等效的,用于描述试样几何尺寸、材料本构关系参数、载荷和位移之间关系的锥-小冲杆试验(cone small punch test,C-SPT)载荷-位...对于均匀、各向同性、幂律硬化的金属材料,以锥形端头小冲杆对试样圆面中心法向施加压载荷,提出基于能量密度等效的,用于描述试样几何尺寸、材料本构关系参数、载荷和位移之间关系的锥-小冲杆试验(cone small punch test,C-SPT)载荷-位移模型,并提出获取材料应力-应变关系和力学性能指标的锥-小冲杆试验新方法。通过有限元分析不同弹性模量、屈服强度和硬化指数的100种预设材料进行新方法的数值验证,及对3种金属材料完成CSPT。结果表明:由新方法预测的应力-应变关系与有限元分析预设曲线和传统单轴拉伸试验结果吻合良好,此外,由新方法获得的抗拉强度与单轴拉伸试验结果误差较小。展开更多
A theory of（N＋1）-dimensional gravity is developed on the basis of the teleparallel equivalent of general relativity（TEGR）.The fundamental gravitational field variables are the（N＋1）-dimensional vector fields,de...A theory of（N＋1）-dimensional gravity is developed on the basis of the teleparallel equivalent of general relativity（TEGR）.The fundamental gravitational field variables are the（N＋1）-dimensional vector fields,defined globally on a manifold M,and the gravitational field is attributed to the torsion.The form of Lagrangian density is quadratic in torsion tensor.We then give an exact five-dimensional spherically symmetric solution（Schwarzschild（4＋1）-dimensions）.Finally,we calculate energy and spatial momentum using gravitational energy-momentum tensor and superpotential 2-form.展开更多
A theory of （1＋1）-dimensional gravity is constructed on the basis of the teleparallel equivalent of general relativity. The fundamental field variables are the tetrad fields ei^μ and the gravity is attributed to t...A theory of （1＋1）-dimensional gravity is constructed on the basis of the teleparallel equivalent of general relativity. The fundamental field variables are the tetrad fields ei^μ and the gravity is attributed to the torsion. A dilatonic spherically symmetric exact solution of the gravitational field equations characterized by two parameters M and Q is derived. The energy associated with this solution is calculated using the two-dimensional gravitational energy- momentum formula.展开更多
Munitions contain casings that consume explosive energy.The blast load(e.g.,peak overpressure and maximum impulse)intensity generated by ammunition explosion will be lower than that generated by a bare charge with equ...Munitions contain casings that consume explosive energy.The blast load(e.g.,peak overpressure and maximum impulse)intensity generated by ammunition explosion will be lower than that generated by a bare charge with equal mass.To evaluate the blast load of a cased charge under different conditions,the equivalent bare mass needs to be calculated.However,the accuracy of existing correlations strongly depends on the empirical determination of relevant controlling parameters and lacks theoretical clarification.In this paper,new correlations are proposed based on a more rigorous theoretical derivation,considering both the mechanical behaviors of the casing’s material and the change of the polytropic exponent during the expansion process of the explosion products.The controlling parameters are attributed to the rupture radius ratio and the polytropic exponent of detonation products expansion to casing rupture state.The reasonability is validated by both comprehensive numerical simulations with dynamic mechanical constitutive model and theoretical derivations.The results calculated by the new correlation show better agreement with the experimental results than those calculated by previous correlations,and the results difference is explained in more consistency with the thermos-physical properties of the charge and mechanical behaviors of casing material.Furthermore,the correlation of the cased-to-bare impulse ratio is also theoretically improved,providing a more accurate theoretical basis for both the equivalent bare mass and impulse evaluation for a cased charge.展开更多
Correction factors of both Rem-meters, the 10 inch diameter single-sphere Remmeter and the standard A-B Rem-meter, were estimated for measuring high energy neutron dose equivalent outside a concrete shielding wall and...Correction factors of both Rem-meters, the 10 inch diameter single-sphere Remmeter and the standard A-B Rem-meter, were estimated for measuring high energy neutron dose equivalent outside a concrete shielding wall and the effects that the emitted neutron spectra become remarkably "harder" penetrated through a concrete shielding wall, and the energy response of the Rem-meter were taken in account. The estimated results could be applied in the measurement of neutron dose equivalent for the intermediate energy heavy ion reactions to avoid the difficulty induced by the energy response of the Rem-meters.展开更多
基金This work was partly supported by the National Key Scientific Instruments to Develop Dedicated Program(Nos.2013YQ090811 and 2016YFF0103800)the National Key Research and Development Program(No.2017YFF0211100).
文摘Si-PIN photodetectors having features such as low cost,small size,low weight,low voltage,and low power consumption are widely used as radiation detectors in electronic personal dosimeters(EPDs).The technical parameters of EPDs based on the Si-PIN photodetectors include photon energy response(PER),angular response,inherent error,and dose rate linearity.Among them,PER is a key parameter for evaluation of EPD measurement accuracy.At present,owing to the limitations of volume,power consumption,and EPD cost,the PER is usually corrected by a combination of single-channel counting techniques and filtering material methods.However,the above-mentioned methods have problems such as poor PER and low measurement accuracy.To solve such problems,in this study,a 1024-channel spectrometry system using a Si-PIN photodetector was developed and fullspectrum measurement in the reference radiation fields was conducted for radiation protection.The measurement results using the few-channel spectroscopy dose method showed that the PER could be controlled within±14%and±2%under the conditions of two and three energy intervals,respectively,with different channel numbers.The PER measured at 0°angle of radiation incidence meets the-29%to+67%requirements of IEC 61526:2010.Meanwhile,the channel number and counts-to-dose conversion factors formed in the experiment can be integrated into an EPD.
文摘Effective atomic numbers for photon energy absorption(ZPEA_(eff)) and their corresponding electron numbers (NPEA_(eff)), and effective macroscopic removal cross sections of fast neutrons(RR) were calculated for 27 different types of three-dimensional dosimeters, four types of phantom materials, and water. The values of ZPEA_(eff) and NPEA_(eff) were obtained using the direct method for energies ranging from 10 keV to 20 MeV. Results are presented relative to water, for direct comparison over the range of examined energies. The effect of monomers that are used in polymer gel dosimeters on the water equivalence is discussed. The relation between Σ_R and hydrogen content was studied. Micelle gel dosimeters are highly promising because our results demonstrate perfect matching between the effective atomic number, electron density number, and fast neutron attenuation coefficient of water.
文摘A theory of （4＋1）-dimensional gravity is developed on the basis of the teleparallel theory equivalent to general relativity. The fundamental gravitational field variables are the five-dimensional vector fields （pentad）, defined globally on a manifold M, and gravity is attributed to the torsion. The Lagrangian density is quadratic in the torsion tensor. We then give the exact five-dimensional solution. The solution is a generalization of the familiar Schwarzschild and Kerr solutions of the four-dimensional teleparallel equivalent of general relativity. We also use the definition of the gravitational energy to calculate the energy and the spatial momentum.
文摘A perfect fluid with self-similarity of the second kind is studied within the framework of the teleparallel equivalent of general relativity （TEGR）. A spacetime which is not asymptotically fiat is derived. The energy conditions of this spacetime are studied. It is shown that after some time the strong energy condition is not enough to satisfy showing a transition from standard matter to dark energy. The singularities of this solution are discussed.
文摘We derive two new retarded solutions in the teleparallel theory equivalent to general relativity （TEGR）. One of these solutions gives a divergent energy. Therefore, we use the regularized expression of the gravitational energymomentum tensor, which is a coordinate dependent. A detailed analysis of the loss of the mass of Bondi space-time is carried out using the flux of the gravitational energy-momentum.
文摘The energy--momentum tensor, which is coordinate-independent, is used to calculate energy, momentum and angular momentum of two different tetrad fields. Although, the two tetrad fields reproduce the same space--time their energies are different. Therefore, a regularized expression of the gravitational energy--momentum tensor of the teleparallel equivalent of general relativity （TEGR）, is used to make the energies of the two tetrad fields equal. The definition of the gravitational energy--momentum is used to investigate the energy within the external event horizon. The components of angular momentum associated with these space--times are calculated. In spite of using a static space--time, we get a non-zero component of angular momentum! Therefore, we derive the Killing vectors associated with these space--times using the definition of the Lie derivative of a second rank tensor in the framework of the TEGR to make the picture more clear.
文摘We apply the energy momentum and angular momentum tensor to a tetrad field, with two unknown functions of radial coordinate, in the framework of a teleparallel equivalent of general relativity （TEGR）. The definition of the gravitational energy is used to investigate the energy within the external event horizon of the dyadosphere region for the Reissner-NordstrSm black hole. We also calculate the spatial momentum and angular momentum.
文摘对于均匀、各向同性、幂律硬化的金属材料,以锥形端头小冲杆对试样圆面中心法向施加压载荷,提出基于能量密度等效的,用于描述试样几何尺寸、材料本构关系参数、载荷和位移之间关系的锥-小冲杆试验(cone small punch test,C-SPT)载荷-位移模型,并提出获取材料应力-应变关系和力学性能指标的锥-小冲杆试验新方法。通过有限元分析不同弹性模量、屈服强度和硬化指数的100种预设材料进行新方法的数值验证,及对3种金属材料完成CSPT。结果表明:由新方法预测的应力-应变关系与有限元分析预设曲线和传统单轴拉伸试验结果吻合良好,此外,由新方法获得的抗拉强度与单轴拉伸试验结果误差较小。
文摘A theory of（N＋1）-dimensional gravity is developed on the basis of the teleparallel equivalent of general relativity（TEGR）.The fundamental gravitational field variables are the（N＋1）-dimensional vector fields,defined globally on a manifold M,and the gravitational field is attributed to the torsion.The form of Lagrangian density is quadratic in torsion tensor.We then give an exact five-dimensional spherically symmetric solution（Schwarzschild（4＋1）-dimensions）.Finally,we calculate energy and spatial momentum using gravitational energy-momentum tensor and superpotential 2-form.
文摘A theory of （1＋1）-dimensional gravity is constructed on the basis of the teleparallel equivalent of general relativity. The fundamental field variables are the tetrad fields ei^μ and the gravity is attributed to the torsion. A dilatonic spherically symmetric exact solution of the gravitational field equations characterized by two parameters M and Q is derived. The energy associated with this solution is calculated using the two-dimensional gravitational energy- momentum formula.
文摘Munitions contain casings that consume explosive energy.The blast load(e.g.,peak overpressure and maximum impulse)intensity generated by ammunition explosion will be lower than that generated by a bare charge with equal mass.To evaluate the blast load of a cased charge under different conditions,the equivalent bare mass needs to be calculated.However,the accuracy of existing correlations strongly depends on the empirical determination of relevant controlling parameters and lacks theoretical clarification.In this paper,new correlations are proposed based on a more rigorous theoretical derivation,considering both the mechanical behaviors of the casing’s material and the change of the polytropic exponent during the expansion process of the explosion products.The controlling parameters are attributed to the rupture radius ratio and the polytropic exponent of detonation products expansion to casing rupture state.The reasonability is validated by both comprehensive numerical simulations with dynamic mechanical constitutive model and theoretical derivations.The results calculated by the new correlation show better agreement with the experimental results than those calculated by previous correlations,and the results difference is explained in more consistency with the thermos-physical properties of the charge and mechanical behaviors of casing material.Furthermore,the correlation of the cased-to-bare impulse ratio is also theoretically improved,providing a more accurate theoretical basis for both the equivalent bare mass and impulse evaluation for a cased charge.
文摘Correction factors of both Rem-meters, the 10 inch diameter single-sphere Remmeter and the standard A-B Rem-meter, were estimated for measuring high energy neutron dose equivalent outside a concrete shielding wall and the effects that the emitted neutron spectra become remarkably "harder" penetrated through a concrete shielding wall, and the energy response of the Rem-meter were taken in account. The estimated results could be applied in the measurement of neutron dose equivalent for the intermediate energy heavy ion reactions to avoid the difficulty induced by the energy response of the Rem-meters.
