The triple-to-double coincidence ratio （TDCR） method of liquid scintillation count- ing is an absolute measurement method of radioactivity. The formulation of the TDCR method and the established TDCR liquid scintill...The triple-to-double coincidence ratio （TDCR） method of liquid scintillation count- ing is an absolute measurement method of radioactivity. The formulation of the TDCR method and the established TDCR liquid scintillation counter are presented in this paper. The NIST standard reference material （SRM） of tritium water was measured to verify the performance of the TDCR liquid scintillation counter.展开更多
In this article, a Bi4π counting method comprised of Bi4πcounter and a new fundamental measurement method was described, which can measures rather more radionuclides and can achieve accuracy of 0.03% to 0.06% (1σ),...In this article, a Bi4π counting method comprised of Bi4πcounter and a new fundamental measurement method was described, which can measures rather more radionuclides and can achieve accuracy of 0.03% to 0.06% (1σ), in principle. Thecorrectness of this method is demonstrated by measurements of 60Co sources which results of activities compared with 47πβ-γ coincident method are in agreement within the measurement errors, and it is readily achieved to accuracy of 0.2%. Finally, the range of the applications for this Bi4π counting method among one hundred or more important radionuclides is also discussed.展开更多
Considering the importance of axle counter function in detecting the train wheels and determining the clearance or occupancy of a track section, it is important to ensure a safe and reliable performance of this system...Considering the importance of axle counter function in detecting the train wheels and determining the clearance or occupancy of a track section, it is important to ensure a safe and reliable performance of this system. In this paper, in order to improve the sensor performance, the authors have focused on the orientation of magnetic sensors’ coils. In order to improve the detection capability of the system, through measuring the induced voltage in the receiver coil, it is important to adjust the relative orientation of the transmitter and receiver coils. Due to the existence of infinite relative orientations, in order to determine the optimum orientation for the sensor coils, Kriging methods which is one of the Response Surface Methodologies (RSMs) is applied. Finite Element Method (FEM) is utilized to provide sample data, as inputs to the Kriging algorithm. The analysis not only provides the optimum relative orientation of the sensor coils, it also improves analysis time, comparing to field based measurements. The analysis results are validated by the laboratory based data implemented in the control and signaling laboratory of the school of railway engineering and also field based tests in Iranian railway.展开更多
逆向发动机常用于对飞行器进行减速或分离。为研究高空稀薄条件下逆向发动机喷流和自由来流的相互作用,构建了由两个逆向喷流和高超声速自由来流相互干扰形成的稀薄流场。通过直接模拟Monte Carlo(direct simulation Monte Carlo,DSMC)...逆向发动机常用于对飞行器进行减速或分离。为研究高空稀薄条件下逆向发动机喷流和自由来流的相互作用,构建了由两个逆向喷流和高超声速自由来流相互干扰形成的稀薄流场。通过直接模拟Monte Carlo(direct simulation Monte Carlo,DSMC)仿真发现在稀薄来流条件下会形成大面积相互干扰区,且该干扰区存在严重非定常流动现象。初步分析认为,该干扰区的范围和非定常演化过程与自由来流动能和逆向发动机喷流流量紧密相关。展开更多
Aim: As the primary aim of this study, we analysed whether the quality of advice provided by pharmacies in the period between 2014 (baseline study) and 2017 (follow-up study) could actually be increased using a single...Aim: As the primary aim of this study, we analysed whether the quality of advice provided by pharmacies in the period between 2014 (baseline study) and 2017 (follow-up study) could actually be increased using a single written performance feedback given to each pharmacy in 2014. The secondary aim of the follow-up examination was to analyse whether the quality of advice differed depending on the professional group providing the advice. Methodology: To ensure the least possible distortion in the comparison between the baseline and the follow-up studies, the study design used for the follow-up examination in 2017 was not changed compared to the baseline examination in 2014. The data for the follow-up examination were therefore collected using the simulated patient method in all 21 pharmacies in a city in the north-east of Germany. Three female and two male test buyers used four different scenarios for self-medication of acute diarrhoea in all of the pharmacies (a total of 84 test purchases). Results: There were significant differences between the overall results from the baseline study (2014) and the follow-up study (2017) (Wilcoxon signed rank test;z = –2.065, p = 0.039, r = 0.225). In the overall average, the pharmacies in 2017 achieved only 2.7 (30%) of 9 possible points whereas in 2014 they achieved 3.3 (37%). The quality of advice between the professional groups did not show any significant differences (Kruskal-Wallis test: χ2(2) = 1.946;p = 0.378, r = 0.027). Conclusions: The quality of advice for acute diarrhoea in adults declined over time. A written performance feedback intended to improve the quality proved ineffective. Interventions with a far greater impact are required to achieve an improvement in the quality of advice provided.展开更多
The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation meth...The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation method and the Extended Negative Factor Counter method at ab initio level. The result indicated that: (1) Amino acid residues, the molecular orbitals of which composed the main components of frontier orbitals of protein chain L (M), are located at the random coil areas of chain L (alpha helix areas of chain M). Since the random coil is flexible and more easy to change its conformation in the electron transfer process and to reduce the energy of the system, and the structure of the alpha helix is reletively stable, this difference might be one of the causes for the electron transfer in photosynthetic reaction center (PRC) only takes place along the L branch. (2) The His residues which axially coordinated to the 'special pair' P and accessory chlorophyll molecules (ABChls) are essentially important for the E-LUMO levels of P and ABChl. But, the corresponding molecular orbitals of these His residues do not appear in the composition of frontier orbitals of protein chains. It means that the interaction between pigment molecules and protein chains do not influence the contribution to the frontier orbitals of protein chains explicitly, but influences the corresponding E-LUMO levels significantly.展开更多
文摘The triple-to-double coincidence ratio （TDCR） method of liquid scintillation count- ing is an absolute measurement method of radioactivity. The formulation of the TDCR method and the established TDCR liquid scintillation counter are presented in this paper. The NIST standard reference material （SRM） of tritium water was measured to verify the performance of the TDCR liquid scintillation counter.
基金The Project Supported by National Natural Science Foundation of China
文摘In this article, a Bi4π counting method comprised of Bi4πcounter and a new fundamental measurement method was described, which can measures rather more radionuclides and can achieve accuracy of 0.03% to 0.06% (1σ), in principle. Thecorrectness of this method is demonstrated by measurements of 60Co sources which results of activities compared with 47πβ-γ coincident method are in agreement within the measurement errors, and it is readily achieved to accuracy of 0.2%. Finally, the range of the applications for this Bi4π counting method among one hundred or more important radionuclides is also discussed.
文摘Considering the importance of axle counter function in detecting the train wheels and determining the clearance or occupancy of a track section, it is important to ensure a safe and reliable performance of this system. In this paper, in order to improve the sensor performance, the authors have focused on the orientation of magnetic sensors’ coils. In order to improve the detection capability of the system, through measuring the induced voltage in the receiver coil, it is important to adjust the relative orientation of the transmitter and receiver coils. Due to the existence of infinite relative orientations, in order to determine the optimum orientation for the sensor coils, Kriging methods which is one of the Response Surface Methodologies (RSMs) is applied. Finite Element Method (FEM) is utilized to provide sample data, as inputs to the Kriging algorithm. The analysis not only provides the optimum relative orientation of the sensor coils, it also improves analysis time, comparing to field based measurements. The analysis results are validated by the laboratory based data implemented in the control and signaling laboratory of the school of railway engineering and also field based tests in Iranian railway.
文摘逆向发动机常用于对飞行器进行减速或分离。为研究高空稀薄条件下逆向发动机喷流和自由来流的相互作用,构建了由两个逆向喷流和高超声速自由来流相互干扰形成的稀薄流场。通过直接模拟Monte Carlo(direct simulation Monte Carlo,DSMC)仿真发现在稀薄来流条件下会形成大面积相互干扰区,且该干扰区存在严重非定常流动现象。初步分析认为,该干扰区的范围和非定常演化过程与自由来流动能和逆向发动机喷流流量紧密相关。
文摘Aim: As the primary aim of this study, we analysed whether the quality of advice provided by pharmacies in the period between 2014 (baseline study) and 2017 (follow-up study) could actually be increased using a single written performance feedback given to each pharmacy in 2014. The secondary aim of the follow-up examination was to analyse whether the quality of advice differed depending on the professional group providing the advice. Methodology: To ensure the least possible distortion in the comparison between the baseline and the follow-up studies, the study design used for the follow-up examination in 2017 was not changed compared to the baseline examination in 2014. The data for the follow-up examination were therefore collected using the simulated patient method in all 21 pharmacies in a city in the north-east of Germany. Three female and two male test buyers used four different scenarios for self-medication of acute diarrhoea in all of the pharmacies (a total of 84 test purchases). Results: There were significant differences between the overall results from the baseline study (2014) and the follow-up study (2017) (Wilcoxon signed rank test;z = –2.065, p = 0.039, r = 0.225). In the overall average, the pharmacies in 2017 achieved only 2.7 (30%) of 9 possible points whereas in 2014 they achieved 3.3 (37%). The quality of advice between the professional groups did not show any significant differences (Kruskal-Wallis test: χ2(2) = 1.946;p = 0.378, r = 0.027). Conclusions: The quality of advice for acute diarrhoea in adults declined over time. A written performance feedback intended to improve the quality proved ineffective. Interventions with a far greater impact are required to achieve an improvement in the quality of advice provided.
文摘The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation method and the Extended Negative Factor Counter method at ab initio level. The result indicated that: (1) Amino acid residues, the molecular orbitals of which composed the main components of frontier orbitals of protein chain L (M), are located at the random coil areas of chain L (alpha helix areas of chain M). Since the random coil is flexible and more easy to change its conformation in the electron transfer process and to reduce the energy of the system, and the structure of the alpha helix is reletively stable, this difference might be one of the causes for the electron transfer in photosynthetic reaction center (PRC) only takes place along the L branch. (2) The His residues which axially coordinated to the 'special pair' P and accessory chlorophyll molecules (ABChls) are essentially important for the E-LUMO levels of P and ABChl. But, the corresponding molecular orbitals of these His residues do not appear in the composition of frontier orbitals of protein chains. It means that the interaction between pigment molecules and protein chains do not influence the contribution to the frontier orbitals of protein chains explicitly, but influences the corresponding E-LUMO levels significantly.
