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
A 37 GHz wide-band programmable divide-by-N frequency divider(FD) composed of a divide-by-2 divider(acting as the first stage) and a divider with a division ratio range of 273–330(acting as the second stage) has been...A 37 GHz wide-band programmable divide-by-N frequency divider(FD) composed of a divide-by-2 divider(acting as the first stage) and a divider with a division ratio range of 273–330(acting as the second stage) has been designed and fabricated using standard 90 nm CMOS technology. The second stage divider consists of a high-speed divide-by-8/9 dual-modulus prescaler, a pulse counter, and a swallow counter. Both the first stage divider(with high speed) and the divide-by-8/9 prescaler employ dynamic current-mode logic(DCML) structure to improve the operating performance. The first stage divider can work from 2 to 40 GHz and the whole divider covers a wide frequency range from 25 to 37 GHz. The input sensitivity is as low as-20 d Bm at 32 GHz and the phase noise at 37 GHz is less than-130 d Bc/Hz at an offset of 1 MHz. The whole chip dissipates 17.88 m W at a supply voltage of 1.2 V and occupies an area of only 730 μm×475 μm.展开更多
用修正法设计任意进制同步计娄数器,是在同步二进制计数器高低位触发器连接具有规律的基础上,个性其中某些位的驱动方程。使之按 N 进制计数器状态计数。修正法较常规用卡诺图化简——求状态方程——求驱动方程的方法,工作效率大为提高...用修正法设计任意进制同步计娄数器,是在同步二进制计数器高低位触发器连接具有规律的基础上,个性其中某些位的驱动方程。使之按 N 进制计数器状态计数。修正法较常规用卡诺图化简——求状态方程——求驱动方程的方法,工作效率大为提高,省去了大量重复的卡诺图化简及繁琐的状态方程,避免了人为因素造成的差错,是一种快速、高效、简便的设计方法。展开更多
This Letter introduces a trigger-controlled Geiger-mode avalanche photodiode （GM-APD）. A hierarchical look- back-upon tree recurrence method is given to predict the performance of trigger-controlled GM-APDs under di...This Letter introduces a trigger-controlled Geiger-mode avalanche photodiode （GM-APD）. A hierarchical look- back-upon tree recurrence method is given to predict the performance of trigger-controlled GM-APDs under different trigger-count upper limits. In addition, the normalized detection probability is defined to evaluate the detection performance of trigger-controlled GM-APDs in typical weak optical signal detection （impulse noise and continuous noise situations）. Theoretical analyses show that the trigger-controlled GM-APD improves the detection performance of GM-APDs in weak optical signal detection via the optimization of the trigger-count upper limit, compared with single-trigger and multi-trigger GM-APDs.展开更多
This study was performed in order to determine visitation at remote areas that would be unaffordable due to logistic reasons. Four TrafxTM vehicle counters, each programmed with different settings, were placed along t...This study was performed in order to determine visitation at remote areas that would be unaffordable due to logistic reasons. Four TrafxTM vehicle counters, each programmed with different settings, were placed along the lone access road to remotely sense the daily use activities and count accuracy at the New Underwood Lake Public Water Access Area. Use was corroborated during daylight hours with game cameras. Data was stratified between weekdays/weekends due to differences between the two periods. Two counter settings, threshold and delay, were best when set at a value of 8, but a value of 16 for delay provided almost equal results. Overall, there were 38 counts of use per day for a total of 2318 over the 61 day period. This study demonstrated how vehicle counters, in combination with game cameras for verification, can aid managers for determining use in remote access areas. Future work may lead to identifying details for producing a surrogate to traditional angler use surveys.展开更多
Neutron detection is used in a wide range of applications in nuclear physics,radiation protection,nuclear fuel cycle,reactor instrumentation,security and industrial measurement.Among the detectors used in this field,w...Neutron detection is used in a wide range of applications in nuclear physics,radiation protection,nuclear fuel cycle,reactor instrumentation,security and industrial measurement.Among the detectors used in this field,we notice the gas-filled 3He proportional counters which have been one of the main detecting tools for thermal and cold neutron detection for many years.This last characteristic has ensured that this detector is one of the best tools for thermal neutron flux measurements in a nuclear reactor control.In the instrumentation and detection laboratory of the Nuclear Research Center,of Birine,we are working toward the design and the development of this type of detectors,indeed,several prototypes of neutron detectors have been realized including the 3He proportional counters.Through this paper,we will present the experimental steps and the obtained results to carry out a 3He proportional counter prototype that was fully developed and tested in our laboratory.A comparison study was made between our detector and a commercial cylindrical 3He neutron detector which was considered in this work as a reference detector:LND252(3He)-PC.The results showed that the characteristics of the gas amplification and the counting plateau for the two counters reference LND 252(3He)-PC and our prototype was of the same order of scale.The experimental tests show that our developed prototype perfect fit with the standard International Electrotechnical Commission(IEC,www.iec.ch)in the operating principle,the technology adopted and obtained technical specifications.展开更多
The new designed at Institute for High Energy Physics （IHEP） technologies ot polystyrene sclntmatol~ ll,aJJu,a 5, molding of polystyrene granules under pressure, melting of granules in forms with mirrors wails, prod...The new designed at Institute for High Energy Physics （IHEP） technologies ot polystyrene sclntmatol~ ll,aJJu,a 5, molding of polystyrene granules under pressure, melting of granules in forms with mirrors wails, production of scintillating granules and detectors on their basis are considered. The main characteristics of the polystyrene scintillators produced by a method of large-block polymerization and a method of extruding of scintillation strips from polymerized blocks are provided in this article also.展开更多
This paper is to detect regions (objects) boundaries, also to isolate and extract individual components from a medical image. This can be done using an active contours to detect regions in a given image, based on tech...This paper is to detect regions (objects) boundaries, also to isolate and extract individual components from a medical image. This can be done using an active contours to detect regions in a given image, based on techniques of curve evolution, Mumford Shah functional for segmentation and level sets. The paper classified the images into different intensity regions based on Markov random field, then detected regions whose boundaries are not necessarily defined by gradient by minimizing an energy of Mumford Shah functional for segmentation which can be seen as a particular case of the minimal partition problem. In the level set formulation, the problem becomes a mean curvature flow like evolving the active contour, which will stop on the desired boundary. The stopping term does not depend on the gradient of the image, as in the classical active contour and the initial curve of level set can be anywhere in the image, and interior contours are automatically detected. The final image segmentation is one closed boundary per actual region in the image.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Project supported by the National Basic Research Program of China(No.2010CB327404)the National Natural Science Foundation of China(No.60901012)
文摘A 37 GHz wide-band programmable divide-by-N frequency divider(FD) composed of a divide-by-2 divider(acting as the first stage) and a divider with a division ratio range of 273–330(acting as the second stage) has been designed and fabricated using standard 90 nm CMOS technology. The second stage divider consists of a high-speed divide-by-8/9 dual-modulus prescaler, a pulse counter, and a swallow counter. Both the first stage divider(with high speed) and the divide-by-8/9 prescaler employ dynamic current-mode logic(DCML) structure to improve the operating performance. The first stage divider can work from 2 to 40 GHz and the whole divider covers a wide frequency range from 25 to 37 GHz. The input sensitivity is as low as-20 d Bm at 32 GHz and the phase noise at 37 GHz is less than-130 d Bc/Hz at an offset of 1 MHz. The whole chip dissipates 17.88 m W at a supply voltage of 1.2 V and occupies an area of only 730 μm×475 μm.
文摘用修正法设计任意进制同步计娄数器,是在同步二进制计数器高低位触发器连接具有规律的基础上,个性其中某些位的驱动方程。使之按 N 进制计数器状态计数。修正法较常规用卡诺图化简——求状态方程——求驱动方程的方法,工作效率大为提高,省去了大量重复的卡诺图化简及繁琐的状态方程,避免了人为因素造成的差错,是一种快速、高效、简便的设计方法。
文摘This Letter introduces a trigger-controlled Geiger-mode avalanche photodiode （GM-APD）. A hierarchical look- back-upon tree recurrence method is given to predict the performance of trigger-controlled GM-APDs under different trigger-count upper limits. In addition, the normalized detection probability is defined to evaluate the detection performance of trigger-controlled GM-APDs in typical weak optical signal detection （impulse noise and continuous noise situations）. Theoretical analyses show that the trigger-controlled GM-APD improves the detection performance of GM-APDs in weak optical signal detection via the optimization of the trigger-count upper limit, compared with single-trigger and multi-trigger GM-APDs.
文摘This study was performed in order to determine visitation at remote areas that would be unaffordable due to logistic reasons. Four TrafxTM vehicle counters, each programmed with different settings, were placed along the lone access road to remotely sense the daily use activities and count accuracy at the New Underwood Lake Public Water Access Area. Use was corroborated during daylight hours with game cameras. Data was stratified between weekdays/weekends due to differences between the two periods. Two counter settings, threshold and delay, were best when set at a value of 8, but a value of 16 for delay provided almost equal results. Overall, there were 38 counts of use per day for a total of 2318 over the 61 day period. This study demonstrated how vehicle counters, in combination with game cameras for verification, can aid managers for determining use in remote access areas. Future work may lead to identifying details for producing a surrogate to traditional angler use surveys.
文摘Neutron detection is used in a wide range of applications in nuclear physics,radiation protection,nuclear fuel cycle,reactor instrumentation,security and industrial measurement.Among the detectors used in this field,we notice the gas-filled 3He proportional counters which have been one of the main detecting tools for thermal and cold neutron detection for many years.This last characteristic has ensured that this detector is one of the best tools for thermal neutron flux measurements in a nuclear reactor control.In the instrumentation and detection laboratory of the Nuclear Research Center,of Birine,we are working toward the design and the development of this type of detectors,indeed,several prototypes of neutron detectors have been realized including the 3He proportional counters.Through this paper,we will present the experimental steps and the obtained results to carry out a 3He proportional counter prototype that was fully developed and tested in our laboratory.A comparison study was made between our detector and a commercial cylindrical 3He neutron detector which was considered in this work as a reference detector:LND252(3He)-PC.The results showed that the characteristics of the gas amplification and the counting plateau for the two counters reference LND 252(3He)-PC and our prototype was of the same order of scale.The experimental tests show that our developed prototype perfect fit with the standard International Electrotechnical Commission(IEC,www.iec.ch)in the operating principle,the technology adopted and obtained technical specifications.
文摘The new designed at Institute for High Energy Physics （IHEP） technologies ot polystyrene sclntmatol~ ll,aJJu,a 5, molding of polystyrene granules under pressure, melting of granules in forms with mirrors wails, production of scintillating granules and detectors on their basis are considered. The main characteristics of the polystyrene scintillators produced by a method of large-block polymerization and a method of extruding of scintillation strips from polymerized blocks are provided in this article also.
文摘This paper is to detect regions (objects) boundaries, also to isolate and extract individual components from a medical image. This can be done using an active contours to detect regions in a given image, based on techniques of curve evolution, Mumford Shah functional for segmentation and level sets. The paper classified the images into different intensity regions based on Markov random field, then detected regions whose boundaries are not necessarily defined by gradient by minimizing an energy of Mumford Shah functional for segmentation which can be seen as a particular case of the minimal partition problem. In the level set formulation, the problem becomes a mean curvature flow like evolving the active contour, which will stop on the desired boundary. The stopping term does not depend on the gradient of the image, as in the classical active contour and the initial curve of level set can be anywhere in the image, and interior contours are automatically detected. The final image segmentation is one closed boundary per actual region in the image.
