Threshold decision is an important function of nuclear instrument control system based on physical parameters threshold decision. Because the conventional decision methods lack correlation with time and conditions, by...Threshold decision is an important function of nuclear instrument control system based on physical parameters threshold decision. Because the conventional decision methods lack correlation with time and conditions, by analyzing the existing methods, some optimized methods are adopted. Considering safety, those methods are improved in data processing algorithms, floating threshold with multiple values, association with specific working condition, etc. These measures im- prove the nuclear instrument control system in fault tolerance and fault diagnosis, especially, the shutdown number of nucle- ar power plant decreases.展开更多
With the simultaneous rise of energy costs and demand for cloud computing, efficient control of data centers becomes crucial. In the data center control problem, one needs to plan at every time step how many servers t...With the simultaneous rise of energy costs and demand for cloud computing, efficient control of data centers becomes crucial. In the data center control problem, one needs to plan at every time step how many servers to switch on or off in order to meet stochastic job arrivals while trying to minimize electricity consumption. This problem becomes particularly challenging when servers can be of various types and jobs from different classes can only be served by certain types of server, as it is often the case in real data centers. We model this problem as a robust Markov decision process(i.e., the transition function is not assumed to be known precisely). We give sufficient conditions(which seem to be reasonable and satisfied in practice) guaranteeing that an optimal threshold policy exists. This property can then be exploited in the design of an efficient solving method, which we provide.Finally, we present some experimental results demonstrating the practicability of our approach and compare with a previous related approach based on model predictive control.展开更多
We propose genuine （k, m）-threshold controlling schemes for controlled teleportation via multi-particle entangled states, where the teleportation of a quantum state from a sender （Alice） to a receiver （Bob） is u...We propose genuine （k, m）-threshold controlling schemes for controlled teleportation via multi-particle entangled states, where the teleportation of a quantum state from a sender （Alice） to a receiver （Bob） is under the control of m supervisors such that k （k≤ m） or more of these supervisors can help Bob recover the transferred state. By construction, anyone of our quantum channels is a genuine multipartite entangled state of which any two parts are inseparable. Their properties are compared and contrasted with those of the well-known GHZ, W, and linear cluster states, and also several other genuine multipartite entangled states recently introduced in the literature.展开更多
We present a （t, .n） threshold multiparty controlled quantum teleportation protocol of an arbitrary m-qubit quantum state between two remote parties. The unknown m-qubit quantum state can be recovered by the receive...We present a （t, .n） threshold multiparty controlled quantum teleportation protocol of an arbitrary m-qubit quantum state between two remote parties. The unknown m-qubit quantum state can be recovered by the receiver under control of a subset of the n controllers if the number of the subset is larger than or equal to a threshold, say, t, but not for any t - 1 or fewer controllers. Our scheme seems to be more practical and more flexible than other existing protocols. The quantum resource required is just m Einstein-Podolsky-Rosen （EPR） pairs plus some single photons. The techniques required are only Bell state measurement, single-qubit unitary operation and yon Neumann measurement. So our scheme is also feasible with present-day technique.展开更多
The emergence of a new network architecture,known as Software Defined Networking(SDN),in the last two decades has overcome some drawbacks of traditional networks in terms of performance,scalability,reliability,securit...The emergence of a new network architecture,known as Software Defined Networking(SDN),in the last two decades has overcome some drawbacks of traditional networks in terms of performance,scalability,reliability,security,and network management.However,the SDN is vulnerable to security threats that target its controller,such as low-rate Distributed Denial of Service(DDoS)attacks,The low-rate DDoS attack is one of the most prevalent attacks that poses a severe threat to SDN network security because the controller is a vital architecture component.Therefore,there is an urgent need to propose a detection approach for this type of attack with a high detection rate and low false-positive rates.Thus,this paper proposes an approach to detect low-rate DDoS attacks on the SDN controller by adapting a dynamic threshold.The proposed approach has been evaluated using four simulation scenarios covering a combination of low-rate DDoS attacks against the SDN controller involving(i)a single host attack targeting a single victim;(ii)a single host attack targeting multiple victims;(iii)multiple hosts attack targeting a single victim;and(iv)multiple hosts attack targeting multiple victims.The proposed approach’s average detection rates are 96.65%,91.83%,96.17%,and 95.33%for the above scenarios,respectively;and its average false-positive rates are 3.33%,8.17%,3.83%,and 4.67%for similar scenarios,respectively.The comparison between the proposed approach and two existing approaches showed that it outperformed them in both categories.展开更多
In this article, a model of a weed control threshold forecast system has been established, with related model solving, data checking, database setting up, and system engineering illustration. Moreover, it is tested by...In this article, a model of a weed control threshold forecast system has been established, with related model solving, data checking, database setting up, and system engineering illustration. Moreover, it is tested by a software with data from a sugar cane planting experimental field in Yunnan, China. The methodology behind the detailed system analysis, design, and engineering has been discussed. The issue of how to create a dynamic data-dependent forecast model of a threshold forecast system, whose threshold changes according to the change of planting environment has been solved. Hence an effective solution has been initiated for further development on an agricultural expert system.展开更多
Since Tian Jun proposed the difference expansion embedding technique,based on which,many reversible watermarking techniques were proposed.However,these methods do not perform well when the payload is high.In this pape...Since Tian Jun proposed the difference expansion embedding technique,based on which,many reversible watermarking techniques were proposed.However,these methods do not perform well when the payload is high.In this paper,we proposed an expandable difference threshold controlled scheme for these three methods.Experiments show that our scheme improves the performance of these three methods for heavy payload.展开更多
Purpose: To test the concept of Statistical Process Control (SPC) as a Quality Assurance (QA) procedure for dose verifications in external beam radiation therapy in conventional and 3D Conformal Radiotherapy (3D-CRT) ...Purpose: To test the concept of Statistical Process Control (SPC) as a Quality Assurance (QA) procedure for dose verifications in external beam radiation therapy in conventional and 3D Conformal Radiotherapy (3D-CRT) treatment of cervical cancer. Materials and Methods: A study of QA verification of target doses of 198 cervical cancer patients undergoing External Beam Radiotherapy (EBRT) treatments at two different cancer treatment centers in Kenya was conducted. The target doses were determined from measured entrance doses by the diode in vivo dosimetry. Process Behavior Charts (PBC) developed by SPC were applied for setting Action Thresholds (AT) on the target doses. The AT set was then proposed as QA limits for acceptance or rejection of verified target doses overtime of the EBRT process. Result and Discussion: Target doses for the 198 patients were calculated and SPC applied to test whether the action limits set by the Process Behavior Charts could be applied as QA for verified doses in EBRT. Results for the two sub-groups of n = 3 and n = 4 that were tested produced action thresholds which are within clinical dose specifications for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. Conclusion: Action thresholds set by SPC were within the clinical dose specification of ±5% uncertainty for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. So the concept of SPC could be applied in setting QA action limits for dose verifications in EBRT.展开更多
随着高比例新能源的接入,互联电力系统不同控制区间的电源结构差异日益增大,有些控制区新能源装机增加、常规机组减少导致调频需求增加但控制能力下降。传统联络线功率频率偏差控制(tie-line power and frequency bias control,TBC)模...随着高比例新能源的接入,互联电力系统不同控制区间的电源结构差异日益增大,有些控制区新能源装机增加、常规机组减少导致调频需求增加但控制能力下降。传统联络线功率频率偏差控制(tie-line power and frequency bias control,TBC)模式下的控制性能评价标准(control performance standard,CPS)标准,通过频率偏差系数来确定各控制区的考核阈值,却未考虑各控制区客观电源结构的影响,在高比例新能源电力系统中的不适应性日益凸显。首先分析了现有CPS标准的前提条件与内涵,揭示了CPS标准在高比例新能源电力系统中的不适应性,进而提出了控制区固有区域控制偏差(area control area,ACE)标准差的概念,利用固有ACE标准差确定考核阈值,提出了CPS标准的改进方法,并与原有CPS标准进行了对比。最后通过算例分析,验证了所提出改进标准比原有CPS标准更加公平合理。展开更多
混合级联型高压直流输电(high voltage direct current,HVDC)系统综合了电网换相换流器(line commutated converter,LCC)和模块化多电平换流器(modular multilevel converters,MMC)的优势,具有良好的工程应用前景,该文对该系统后续换相...混合级联型高压直流输电(high voltage direct current,HVDC)系统综合了电网换相换流器(line commutated converter,LCC)和模块化多电平换流器(modular multilevel converters,MMC)的优势,具有良好的工程应用前景,该文对该系统后续换相失败预判及抑制开展了研究。首先,明确了换相失败恢复期间各阶段控制器交互作用以及换相电压跌落产生的后续换相失败风险。其次,在考虑MMC与LCC端口直流电压交互作用和混合级联型HVDC系统中各控制器作用的基础上,提出了一种通过对比换相电压有效值与阈值电压的后续换相失败预判方法;然后,提出了MMC提供持续无功支持和动态更改定关断角控制(constant extinction angle control,CEAC)中关断角指令值的协调控制策略,以实现后续换相失败抑制;最后,在PSCAD/EMTDC中搭建了相应的混合级联系统电磁暂态仿真模型,对预判方法的准确性和抑制策略的有效性进行了验证。展开更多
目的建立测定艾司唑仑原料中基因毒性杂质甲醛的柱前衍生高效液相色谱方法,考察国内4家企业艾司唑仑原料中甲醛含量水平。方法色谱柱为CAPCELL PAK C8柱,流动相为水-乙腈(60:40),流速为1.0 mL/min,检测波长为360 nm,柱温为30℃,进样量...目的建立测定艾司唑仑原料中基因毒性杂质甲醛的柱前衍生高效液相色谱方法,考察国内4家企业艾司唑仑原料中甲醛含量水平。方法色谱柱为CAPCELL PAK C8柱,流动相为水-乙腈(60:40),流速为1.0 mL/min,检测波长为360 nm,柱温为30℃,进样量为10μL。结果甲醛2,4-二硝基苯腙在浓度0.05~1μg/mL范围内与峰面积线性关系良好(r=0.9998);检测限和定量限分别为6和20μg/g;进样精密度和重复性试验的RSD分别为0.2%和1.4%(n=6);平均加样回收率为101.8%,RSD为0.8%(n=6)。1家企业的2批原料中甲醛含量远超过控制阈值,另外5批原料中甲醛含量均小于定量限。结论建立的甲醛测定方法准确度高,灵敏度强。建议甲醛含量超过控制阈值的生产企业制定合理的控制策略。展开更多
Long departure-taxi-out time leads to significant airport surface congestion, fuel-burn costs, and excessive emissions of greenhouse gases. To reduce these undesirable effects, a Predicted taxi-out time-based Dynamic ...Long departure-taxi-out time leads to significant airport surface congestion, fuel-burn costs, and excessive emissions of greenhouse gases. To reduce these undesirable effects, a Predicted taxi-out time-based Dynamic Pushback Control(PDPC) method is proposed. The implementation of this method requires two steps: first, the taxi-out times for aircraft are predicted by the leastsquares support-vector regression approach of which the parameters are optimized by an introduced improved Firefly algorithm. Then, a dynamic pushback control model equipped with a linear gate-hold penalty function is built, along with a proposed iterative taxiway queue-threshold optimization algorithm for solving the model. A case study with data obtained from Beijing International airport(PEK) is presented. The taxi-out time prediction model achieves predictive accuracy within 3 min and 5 min by 84.71% and 95.66%, respectively. The results of the proposed pushback method show that total operation cost and fuel-burn cost achieve a 14.0% and 21.1%reduction, respectively, as compared to the traditional K-control policy.(3) From the perspective of implementation, using PDPC policy can significantly reduce the queue length in taxiway and taxi-out time. The total operation cost and fuel-burn cost can be curtailed by 37.2% and 52.1%,respectively, as compared to the non-enforcement of any pushback control mechanism. These results show that the proposed pushback control model can reduce fuel-burn costs and airport surface congestion effectively.展开更多
基金Research Project of Hunan Province Education Department(No.14C0972)
文摘Threshold decision is an important function of nuclear instrument control system based on physical parameters threshold decision. Because the conventional decision methods lack correlation with time and conditions, by analyzing the existing methods, some optimized methods are adopted. Considering safety, those methods are improved in data processing algorithms, floating threshold with multiple values, association with specific working condition, etc. These measures im- prove the nuclear instrument control system in fault tolerance and fault diagnosis, especially, the shutdown number of nucle- ar power plant decreases.
文摘With the simultaneous rise of energy costs and demand for cloud computing, efficient control of data centers becomes crucial. In the data center control problem, one needs to plan at every time step how many servers to switch on or off in order to meet stochastic job arrivals while trying to minimize electricity consumption. This problem becomes particularly challenging when servers can be of various types and jobs from different classes can only be served by certain types of server, as it is often the case in real data centers. We model this problem as a robust Markov decision process(i.e., the transition function is not assumed to be known precisely). We give sufficient conditions(which seem to be reasonable and satisfied in practice) guaranteeing that an optimal threshold policy exists. This property can then be exploited in the design of an efficient solving method, which we provide.Finally, we present some experimental results demonstrating the practicability of our approach and compare with a previous related approach based on model predictive control.
基金Supported by National Natural Science Foundation of China under Grant Nos.11004050 and 10874019Key Project of Chinese Ministry of Education under Grant No.211119+2 种基金Scientific Research Fund of Hunan Provincial Education Department of China under Grant Nos.10B013 and 09A013Excellent Talents Program of Hengyang Normal University of China under Grant No.2010YCJH01Science Foundation of Hengyang Normal University of China under Grant No.10B69
文摘We propose genuine （k, m）-threshold controlling schemes for controlled teleportation via multi-particle entangled states, where the teleportation of a quantum state from a sender （Alice） to a receiver （Bob） is under the control of m supervisors such that k （k≤ m） or more of these supervisors can help Bob recover the transferred state. By construction, anyone of our quantum channels is a genuine multipartite entangled state of which any two parts are inseparable. Their properties are compared and contrasted with those of the well-known GHZ, W, and linear cluster states, and also several other genuine multipartite entangled states recently introduced in the literature.
基金Supported by the National Basic Research Program of China (973 Program) under Grant No.2007CB311100the National Natural Science Foundation of China under Grant No.60873191+3 种基金the National High Technology Research and Development Program of China under Grant No.2006AA01Z419the Major Research plan of the National Natural Science Foundation of China under Grant No.90604023the Scientific Research Common Program of Beijing Municipal Commission of Education under Grant No.KM200810005004the Scientific Research Foundation for the Youth of Beijing University of Technology under Grant No.97007016200701
文摘We present a （t, .n） threshold multiparty controlled quantum teleportation protocol of an arbitrary m-qubit quantum state between two remote parties. The unknown m-qubit quantum state can be recovered by the receiver under control of a subset of the n controllers if the number of the subset is larger than or equal to a threshold, say, t, but not for any t - 1 or fewer controllers. Our scheme seems to be more practical and more flexible than other existing protocols. The quantum resource required is just m Einstein-Podolsky-Rosen （EPR） pairs plus some single photons. The techniques required are only Bell state measurement, single-qubit unitary operation and yon Neumann measurement. So our scheme is also feasible with present-day technique.
基金This work was supported by Universiti Sains Malaysia under external grant(Grant Number 304/PNAV/650958/U154).
文摘The emergence of a new network architecture,known as Software Defined Networking(SDN),in the last two decades has overcome some drawbacks of traditional networks in terms of performance,scalability,reliability,security,and network management.However,the SDN is vulnerable to security threats that target its controller,such as low-rate Distributed Denial of Service(DDoS)attacks,The low-rate DDoS attack is one of the most prevalent attacks that poses a severe threat to SDN network security because the controller is a vital architecture component.Therefore,there is an urgent need to propose a detection approach for this type of attack with a high detection rate and low false-positive rates.Thus,this paper proposes an approach to detect low-rate DDoS attacks on the SDN controller by adapting a dynamic threshold.The proposed approach has been evaluated using four simulation scenarios covering a combination of low-rate DDoS attacks against the SDN controller involving(i)a single host attack targeting a single victim;(ii)a single host attack targeting multiple victims;(iii)multiple hosts attack targeting a single victim;and(iv)multiple hosts attack targeting multiple victims.The proposed approach’s average detection rates are 96.65%,91.83%,96.17%,and 95.33%for the above scenarios,respectively;and its average false-positive rates are 3.33%,8.17%,3.83%,and 4.67%for similar scenarios,respectively.The comparison between the proposed approach and two existing approaches showed that it outperformed them in both categories.
文摘In this article, a model of a weed control threshold forecast system has been established, with related model solving, data checking, database setting up, and system engineering illustration. Moreover, it is tested by a software with data from a sugar cane planting experimental field in Yunnan, China. The methodology behind the detailed system analysis, design, and engineering has been discussed. The issue of how to create a dynamic data-dependent forecast model of a threshold forecast system, whose threshold changes according to the change of planting environment has been solved. Hence an effective solution has been initiated for further development on an agricultural expert system.
基金the National High Technology Research and Development Program (863) of China (No.2007AA02Z452) the National Natural Science Foundation of China (Nos.30570511 and 30770589)
文摘Since Tian Jun proposed the difference expansion embedding technique,based on which,many reversible watermarking techniques were proposed.However,these methods do not perform well when the payload is high.In this paper,we proposed an expandable difference threshold controlled scheme for these three methods.Experiments show that our scheme improves the performance of these three methods for heavy payload.
文摘Purpose: To test the concept of Statistical Process Control (SPC) as a Quality Assurance (QA) procedure for dose verifications in external beam radiation therapy in conventional and 3D Conformal Radiotherapy (3D-CRT) treatment of cervical cancer. Materials and Methods: A study of QA verification of target doses of 198 cervical cancer patients undergoing External Beam Radiotherapy (EBRT) treatments at two different cancer treatment centers in Kenya was conducted. The target doses were determined from measured entrance doses by the diode in vivo dosimetry. Process Behavior Charts (PBC) developed by SPC were applied for setting Action Thresholds (AT) on the target doses. The AT set was then proposed as QA limits for acceptance or rejection of verified target doses overtime of the EBRT process. Result and Discussion: Target doses for the 198 patients were calculated and SPC applied to test whether the action limits set by the Process Behavior Charts could be applied as QA for verified doses in EBRT. Results for the two sub-groups of n = 3 and n = 4 that were tested produced action thresholds which are within clinical dose specifications for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. Conclusion: Action thresholds set by SPC were within the clinical dose specification of ±5% uncertainty for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. So the concept of SPC could be applied in setting QA action limits for dose verifications in EBRT.
文摘随着高比例新能源的接入,互联电力系统不同控制区间的电源结构差异日益增大,有些控制区新能源装机增加、常规机组减少导致调频需求增加但控制能力下降。传统联络线功率频率偏差控制(tie-line power and frequency bias control,TBC)模式下的控制性能评价标准(control performance standard,CPS)标准,通过频率偏差系数来确定各控制区的考核阈值,却未考虑各控制区客观电源结构的影响,在高比例新能源电力系统中的不适应性日益凸显。首先分析了现有CPS标准的前提条件与内涵,揭示了CPS标准在高比例新能源电力系统中的不适应性,进而提出了控制区固有区域控制偏差(area control area,ACE)标准差的概念,利用固有ACE标准差确定考核阈值,提出了CPS标准的改进方法,并与原有CPS标准进行了对比。最后通过算例分析,验证了所提出改进标准比原有CPS标准更加公平合理。
文摘目的建立测定艾司唑仑原料中基因毒性杂质甲醛的柱前衍生高效液相色谱方法,考察国内4家企业艾司唑仑原料中甲醛含量水平。方法色谱柱为CAPCELL PAK C8柱,流动相为水-乙腈(60:40),流速为1.0 mL/min,检测波长为360 nm,柱温为30℃,进样量为10μL。结果甲醛2,4-二硝基苯腙在浓度0.05~1μg/mL范围内与峰面积线性关系良好(r=0.9998);检测限和定量限分别为6和20μg/g;进样精密度和重复性试验的RSD分别为0.2%和1.4%(n=6);平均加样回收率为101.8%,RSD为0.8%(n=6)。1家企业的2批原料中甲醛含量远超过控制阈值,另外5批原料中甲醛含量均小于定量限。结论建立的甲醛测定方法准确度高,灵敏度强。建议甲醛含量超过控制阈值的生产企业制定合理的控制策略。
基金partially supported by the National Natural Science Foundation of China-Civil Aviation Joint Fund(Nos.U1533203,U1233124.)
文摘Long departure-taxi-out time leads to significant airport surface congestion, fuel-burn costs, and excessive emissions of greenhouse gases. To reduce these undesirable effects, a Predicted taxi-out time-based Dynamic Pushback Control(PDPC) method is proposed. The implementation of this method requires two steps: first, the taxi-out times for aircraft are predicted by the leastsquares support-vector regression approach of which the parameters are optimized by an introduced improved Firefly algorithm. Then, a dynamic pushback control model equipped with a linear gate-hold penalty function is built, along with a proposed iterative taxiway queue-threshold optimization algorithm for solving the model. A case study with data obtained from Beijing International airport(PEK) is presented. The taxi-out time prediction model achieves predictive accuracy within 3 min and 5 min by 84.71% and 95.66%, respectively. The results of the proposed pushback method show that total operation cost and fuel-burn cost achieve a 14.0% and 21.1%reduction, respectively, as compared to the traditional K-control policy.(3) From the perspective of implementation, using PDPC policy can significantly reduce the queue length in taxiway and taxi-out time. The total operation cost and fuel-burn cost can be curtailed by 37.2% and 52.1%,respectively, as compared to the non-enforcement of any pushback control mechanism. These results show that the proposed pushback control model can reduce fuel-burn costs and airport surface congestion effectively.
