This paper studies phantom linear scalar field （LSF） and phantom non-linear Born-Infeld （NLBI） scalar field with square potential of the form V（Ф） =1/2m^2Ф^2. The equation of state parameter w（z）, and evolut...This paper studies phantom linear scalar field （LSF） and phantom non-linear Born-Infeld （NLBI） scalar field with square potential of the form V（Ф） =1/2m^2Ф^2. The equation of state parameter w（z）, and evolution of scale factor a（t） in both phantom LSF and phantom NLBI scalar model are explored. The age of universe Hot and the transition redshift Z are obtained. The Gold data set of 157-SN-Ia is used to constrain parameters of the two models by numerical calculation. The phantom LSF is slightly better than the phantom NLBI type scalar field model for a large m. Although a smaller m corresponding to a slower rolling of field Ф better fits the observation data, the difference between phantom NLBI scalar field and phantom LSF is not distinct in this case.展开更多
This paper reviews the development of f(R) gravity theory and Phantom and Quintessence fields. Specifically, we present a new general action of f(R) gravity and Phantom and Quintessence fields coupled to scalar curvat...This paper reviews the development of f(R) gravity theory and Phantom and Quintessence fields. Specifically, we present a new general action of f(R) gravity and Phantom and Quintessence fields coupled to scalar curvature. Then, we deduce Euler-Lagrange Equations of different fields, matter tensor and effective matter tensor. Additionally, this paper obtains the general pressure, density and speed sound of the new general field action, and investigates different cosmological evolutions with inflation. Further, this paper investigates a general f(R) gravity theory with a general matter action and obtains the different field equations, general matter tensor and effective matter tensor. Besides, this paper obtains the effective Strong Energy Condition (SEC) and effective Null Energy Condition (NEC). Then, we prove that when f(R) approaches to R, the effective SEC and the effective NEC approach to the usual SEC and the usual NEC, respectively. Finally, this paper presents a general action of f(R) gravity, Quintessence and Phantom fields and their applications.展开更多
We present the Empirical Formula (EF) to calculate the phantom scatter factor, S<sub>p</sub>, of small radiation fields under charge particle dis-equilibrium conditions. The Empirical Formula (EF) was veri...We present the Empirical Formula (EF) to calculate the phantom scatter factor, S<sub>p</sub>, of small radiation fields under charge particle dis-equilibrium conditions. The Empirical Formula (EF) was verified by examining the calculated data with experimentally measured data utilizing the anthropomorphic phantom in twelve different combinations of beam entry and point location, where the value for S<sub>p</sub> per tissue composition was within 3% in 8/12 cases, 5% in 1/12 cases, and 10% in 3/12 cases. Our results showed a good agreement with experimental data to less than 1% when the ion chamber was surrounded by the homogeneous tissue, whether lung, soft tissue, or bone. Indicating that the prediction of the equation is valid, and it can be reliably used for phantom scatter factor calculation for different homogeneous media under charge particle dis- equilibrium conditions.展开更多
We investigate the phantom dark energy model derived from the scalar field with a negative kinetic term. By assuming a particular relation between the time derivative of the phantom field and the Hubble function, an e...We investigate the phantom dark energy model derived from the scalar field with a negative kinetic term. By assuming a particular relation between the time derivative of the phantom field and the Hubble function, an exact solution of the model is constructed. Absence of the ＇big rip＇ singularity is shown explicitly. We then derive special features of phantom dark energy model and show that its predictions are consistent with all astrophysical observations.展开更多
Abstract: The aim of this study was to develop a cheap, locally made and friendly applicable phantom for gamma camera quality control and to test its validity relative to standard results (intrinsic and extrinsic spat...Abstract: The aim of this study was to develop a cheap, locally made and friendly applicable phantom for gamma camera quality control and to test its validity relative to standard results (intrinsic and extrinsic spatial linearity and intrinsic and extrinsic uniformity) of gamma camera SPECT. And the significance of this experimental study was to introduce a multi-purpose phantom for gamma camera which could overcome the risk accompanied by quality control test procedure such as detector crystal damage and the appearance of moiré patterns. The results of the developed phantom showed an average count difference of 0.7% relative to the standard phantom and about 4% in X- to Y-axis directions relative to the standard phantom. Also, the measured absolute linearity was 0.63 mm in X direction and 0.64 mm in Y direction for the UFOV compare with 0.70 mm value of acceptance test. And the I.U. and D.U. of the developed phantom were 3.18% and 2.27% respectively for the UFOV relative to the standard phantom I.U. and D.U. (2.0% and 1.5%) for the UFOV respectively.展开更多
In this study,we investigate the expansion of the FRLW universe in the open,closed,and flat geometries.The universe is dominated by a scalar field(spatially homogeneous)as a source of dark energy.We consider the three...In this study,we investigate the expansion of the FRLW universe in the open,closed,and flat geometries.The universe is dominated by a scalar field(spatially homogeneous)as a source of dark energy.We consider the three different classes of scalar fields-quintessence,tachyonic,and phantom field-for our analysis.A mathematical analysis is carried out by considering these three scalar fields with exponential and power-law potentials.Both potentials give exponential expansion in the open,closed,and flat FRLW universes.It is found that quintessence,tachyonic,and phantom scalar fields are indistinguishable under the slow roll approximation.展开更多
磁热声成像(MMTAI)是一种新型的人体疾病早期检测电阻抗成像技术,融合了传统电阻抗成像高对比度和超声成像高分辨率的优势。为了验证磁热声成像针对生物组织的可行性,研究了磁热声成像的原理,并搭建了相应的实验系统。研究结果表明:将...磁热声成像(MMTAI)是一种新型的人体疾病早期检测电阻抗成像技术,融合了传统电阻抗成像高对比度和超声成像高分辨率的优势。为了验证磁热声成像针对生物组织的可行性,研究了磁热声成像的原理,并搭建了相应的实验系统。研究结果表明:将低电导率目标体置于μs级脉冲宽度的脉冲磁场中,会在目标体内产生涡流,目标体吸收焦耳热后瞬时膨胀并发出声信号,声信号含有目标体的电导率信息;利用电磁场与声场理论所推导的目标体声源计算式反映了声源与电导率之间的关系;对磁-热-声多场耦合作用下产生的热声信号进行检测和分析,再利用时间反演法重建声源分布;将含质量分数10%氯化钠的凝胶仿体模型置于μs级脉冲宽度的脉冲磁场中,采用中心频率为1 MHz的超声换能器采集超声信号,信号被放大60 d B后的峰峰值约为4 m V,利用旋转凝胶仿体采集的100组信号所重建的热声图像能反映低电导率凝胶仿体的电导率分布。此实验验证了该方法用于低电导率介质成像的可行性,为该方法用于生物组织成像的研究提供了依据。展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos.10573012, 10575068）, and the Shanghai Municipal Science and Technology Commission （Grant No.04dz05905）
文摘This paper studies phantom linear scalar field （LSF） and phantom non-linear Born-Infeld （NLBI） scalar field with square potential of the form V（Ф） =1/2m^2Ф^2. The equation of state parameter w（z）, and evolution of scale factor a（t） in both phantom LSF and phantom NLBI scalar model are explored. The age of universe Hot and the transition redshift Z are obtained. The Gold data set of 157-SN-Ia is used to constrain parameters of the two models by numerical calculation. The phantom LSF is slightly better than the phantom NLBI type scalar field model for a large m. Although a smaller m corresponding to a slower rolling of field Ф better fits the observation data, the difference between phantom NLBI scalar field and phantom LSF is not distinct in this case.
文摘This paper reviews the development of f(R) gravity theory and Phantom and Quintessence fields. Specifically, we present a new general action of f(R) gravity and Phantom and Quintessence fields coupled to scalar curvature. Then, we deduce Euler-Lagrange Equations of different fields, matter tensor and effective matter tensor. Additionally, this paper obtains the general pressure, density and speed sound of the new general field action, and investigates different cosmological evolutions with inflation. Further, this paper investigates a general f(R) gravity theory with a general matter action and obtains the different field equations, general matter tensor and effective matter tensor. Besides, this paper obtains the effective Strong Energy Condition (SEC) and effective Null Energy Condition (NEC). Then, we prove that when f(R) approaches to R, the effective SEC and the effective NEC approach to the usual SEC and the usual NEC, respectively. Finally, this paper presents a general action of f(R) gravity, Quintessence and Phantom fields and their applications.
文摘We present the Empirical Formula (EF) to calculate the phantom scatter factor, S<sub>p</sub>, of small radiation fields under charge particle dis-equilibrium conditions. The Empirical Formula (EF) was verified by examining the calculated data with experimentally measured data utilizing the anthropomorphic phantom in twelve different combinations of beam entry and point location, where the value for S<sub>p</sub> per tissue composition was within 3% in 8/12 cases, 5% in 1/12 cases, and 10% in 3/12 cases. Our results showed a good agreement with experimental data to less than 1% when the ion chamber was surrounded by the homogeneous tissue, whether lung, soft tissue, or bone. Indicating that the prediction of the equation is valid, and it can be reliably used for phantom scatter factor calculation for different homogeneous media under charge particle dis- equilibrium conditions.
文摘We investigate the phantom dark energy model derived from the scalar field with a negative kinetic term. By assuming a particular relation between the time derivative of the phantom field and the Hubble function, an exact solution of the model is constructed. Absence of the ＇big rip＇ singularity is shown explicitly. We then derive special features of phantom dark energy model and show that its predictions are consistent with all astrophysical observations.
文摘Abstract: The aim of this study was to develop a cheap, locally made and friendly applicable phantom for gamma camera quality control and to test its validity relative to standard results (intrinsic and extrinsic spatial linearity and intrinsic and extrinsic uniformity) of gamma camera SPECT. And the significance of this experimental study was to introduce a multi-purpose phantom for gamma camera which could overcome the risk accompanied by quality control test procedure such as detector crystal damage and the appearance of moiré patterns. The results of the developed phantom showed an average count difference of 0.7% relative to the standard phantom and about 4% in X- to Y-axis directions relative to the standard phantom. Also, the measured absolute linearity was 0.63 mm in X direction and 0.64 mm in Y direction for the UFOV compare with 0.70 mm value of acceptance test. And the I.U. and D.U. of the developed phantom were 3.18% and 2.27% respectively for the UFOV relative to the standard phantom I.U. and D.U. (2.0% and 1.5%) for the UFOV respectively.
文摘In this study,we investigate the expansion of the FRLW universe in the open,closed,and flat geometries.The universe is dominated by a scalar field(spatially homogeneous)as a source of dark energy.We consider the three different classes of scalar fields-quintessence,tachyonic,and phantom field-for our analysis.A mathematical analysis is carried out by considering these three scalar fields with exponential and power-law potentials.Both potentials give exponential expansion in the open,closed,and flat FRLW universes.It is found that quintessence,tachyonic,and phantom scalar fields are indistinguishable under the slow roll approximation.
文摘磁热声成像(MMTAI)是一种新型的人体疾病早期检测电阻抗成像技术,融合了传统电阻抗成像高对比度和超声成像高分辨率的优势。为了验证磁热声成像针对生物组织的可行性,研究了磁热声成像的原理,并搭建了相应的实验系统。研究结果表明:将低电导率目标体置于μs级脉冲宽度的脉冲磁场中,会在目标体内产生涡流,目标体吸收焦耳热后瞬时膨胀并发出声信号,声信号含有目标体的电导率信息;利用电磁场与声场理论所推导的目标体声源计算式反映了声源与电导率之间的关系;对磁-热-声多场耦合作用下产生的热声信号进行检测和分析,再利用时间反演法重建声源分布;将含质量分数10%氯化钠的凝胶仿体模型置于μs级脉冲宽度的脉冲磁场中,采用中心频率为1 MHz的超声换能器采集超声信号,信号被放大60 d B后的峰峰值约为4 m V,利用旋转凝胶仿体采集的100组信号所重建的热声图像能反映低电导率凝胶仿体的电导率分布。此实验验证了该方法用于低电导率介质成像的可行性,为该方法用于生物组织成像的研究提供了依据。
