An optimized robust filtering algorithm for uncertain discrete-time systemsis presented. To get a series of computational equations, the uncertain part generated by theuncertain systematic matrix in the expression of ...An optimized robust filtering algorithm for uncertain discrete-time systemsis presented. To get a series of computational equations, the uncertain part generated by theuncertain systematic matrix in the expression of the error-covariance matrix of time update stateestimation is optimized and the least upper bound of the uncertain part is given. By means of theseresults, the equivalent systematic matrix is obtained and a robust time update algorithm is builtup. On the other hand, uncertain parts generated by the uncertain observation matrix in theexpression of the error-covariance matrix of measurement update state estimation are optimized, andthe largest lower bound of the uncertain part is given. Thus both the time update and measurementupdate algorithms are developed. By means of the matrix inversion formula, the expression structuresof both time update and measurement update algorithms are all simplified. Moreover, the convergencecondition of a robust filter is developed to make the results easy to application. The results offlight data processing show that the method presented in this paper is efficient.展开更多
The effectiveness of deep-bed filtration with respect to suspension formed during the preceding processes is evaluated by the test of filterability. The properties and concentration of the suspension being filtered ar...The effectiveness of deep-bed filtration with respect to suspension formed during the preceding processes is evaluated by the test of filterability. The properties and concentration of the suspension being filtered are affected by the efficiency of the preceding aggregation and separation processes. The basic principles of the test of filterability are based on the mechanistic model of filtration. The equations in the mathematical model of the mechanistic conception of filtration are derived from the theory of filtration. The arrangement of the pilot filtration plant for the determination of filterability of flocculent suspension is presented in this paper. The test of filterability is carried out with a thin-layer filter element. The design of a filter element arrangement and its installation are also disclosed in this paper. The inter-dependence of the coefficient of filtration efficiency on the specific volume of intercepted suspensions, filter media grain sizes and different filtration velocities are graphically presented. In addition, the effect of the filter bed clogging resulting from the properties of different suspensions on the head loss generated, the length of filtration cycle and quality of filtrate produced are also shown in this paper.展开更多
Retrofitting older vehicles with diesel particulate filter（DPF） is a cost-effective measure to quickly and efficiently reduce particulate matter emissions. This study experimentally analyzes real-world performance o...Retrofitting older vehicles with diesel particulate filter（DPF） is a cost-effective measure to quickly and efficiently reduce particulate matter emissions. This study experimentally analyzes real-world performance of buses retrofitted with CRT DPFs. 18 in-use Euro III technology urban and intercity buses were investigated for a period of 12 months. The influence of the DPF and of the vehicle natural aging on buses fuel economy are analyzed and discussed. While the effect of natural deterioration is about 1.2%–1.3%, DPF contribution to fuel economy penalty is found to be 0.6% to 1.8%, depending on the bus type. DPF filtration efficiency is analyzed throughout the study and found to be in average 96% in the size range of 23–560 nm. Four different load and non-load engine operating modes are investigated on their appropriateness for roadworthiness tests. High idle is found to be the most suitable regime for PN diagnostics considering particle number filtration efficiency.展开更多
Generation of polydisperse KCl aerosol with a new salt aerosol generator was investigated, Special attention was paid on particles with diameters between 3 and 10 μm. The main improvement consists of the different ro...Generation of polydisperse KCl aerosol with a new salt aerosol generator was investigated, Special attention was paid on particles with diameters between 3 and 10 μm. The main improvement consists of the different routes of KCl solution droplets. In traditional generators, the solution droplets travel through one cylinder; while in the case analyzed here, after spray atomization, the droplets travel through two cylinders in series. The first cylinder was fed with warm air and the second one with cold air. In such way, the complete evaporation of the water from the droplets can be ensured. The influencing factors of the generated aerosol size distribution were investigated. The data measured show that the concentration of generated aerosol becomes higher both increasing the flow rate of the KCI solution injected in the first cylinder and increasing the concentration in the solution. The temperature of solution influences mainly the generation of smaller KCI particles （0,3-3 μm）. The amount of hot air used in the generation process increases the concentration of larger KC1 particles （〉3 μm） while cold air does not have the same effect. The aerosol generator is able to generate KC1 aerosol stably. This instrument can be used effectively for testing air filters for automotive.展开更多
The accuracy of the HB2 standard model attitude measurement has an important impact on the hypersonic wind tunnel data assessment.The limited size of the model and the existence of external vibrations make it challeng...The accuracy of the HB2 standard model attitude measurement has an important impact on the hypersonic wind tunnel data assessment.The limited size of the model and the existence of external vibrations make it challenging to obtain real-time reliable attitude measurement.To reduce the influence of attitude errors on test results,this paper proposes a Quaternion Nonlinear Complementary Filter(QNCF)attitude determination algorithm based on Microelectromechanical Inertial Measurement Unit(MEMS-IMU).Firstly,the threshold-based PI control strategy is adopted to eliminate noise effect according to the Acceleration Magnitude Detector(AMD).Then,the flexible quaternion method is updated to carry out attitude estimation which is operational and easy to be embedded in the Field Programmable Gate Array(FPGA).Finally,a high-precision three-axis turntable test and a hypersonic wind tunnel test are performed.The results show that the pitchroll attitude errors are within 0.05°and 0.08°in the high-precision three-axis turntable test in a calculation time of 100 s respectively,and the attitude error is within 0.3°after the elastic angle correction in the hypersonic wind tunnel test.The proposed method can provide accurate real-time attitude reference for the analysis of the actual movement of the model,exhibiting certain engineering application value with robustness and simplicity.展开更多
In this paper,we investigate the matched filter based spectrum sensing in a more reasonable cognitive radio(CR) scenario when the primary user(PU) has more than one transmit power levels,as regulated in most standards...In this paper,we investigate the matched filter based spectrum sensing in a more reasonable cognitive radio(CR) scenario when the primary user(PU) has more than one transmit power levels,as regulated in most standards,i.e.,IEEE 802.11 Series,GSM,LTE,LTE-A,etc.This new multiple primary transmit power(MPTP) scenario is specialized by two different targets:detecting the presence of PU and identifying the power level.Compared to the traditional binary sensing where only the presence of PU is checked,SU may attain more information about the primary network(making CR more "intelligent") and design the subsequent optimization strategy.The key technology is the multiple hypothesis testing as opposed to the traditional binary hypothesis testing.We discuss two situations under whether the channel phase is known or not,and we derive the closed form solutions for decision regions and several performance metrics,from which some interesting phenomenons are observed and the related discussions are presented.Numerical examples are provided to corroborate the proposed studies.展开更多
With the fast development of bridge construction in mountainous and seismic areas,it is necessary to conduct related research. Based on the design of a shaking table model test,here are the following test results: the...With the fast development of bridge construction in mountainous and seismic areas,it is necessary to conduct related research. Based on the design of a shaking table model test,here are the following test results: the filtering effect exists in soil and is affected by the dynamic constraint conditions,the amplitude is strengthened around the natural frequency and weakened in other frequency bands in the Fourier spectrum. Since the acceleration scaling effect occurred on a sloped surface,the acceleration response decreases from the outside to the inside in soil. The dynamic response is relatively strong near the slip surface in bedrock due to the reflection of seismic waves. The failure mode of landslide is decided by the slope angle and slipping mass distribution, and the test shows the front row stabilizing piles should keep a proper distance from bridge foundation so that seismic resistance can be guaranteed for the bridge foundation.展开更多
This paper deals with the characterisation and study of physico-chemical stability of ceramic filters from clays and rice husk obtained from the far north region of Cameroon (Logone Valley) and their application in po...This paper deals with the characterisation and study of physico-chemical stability of ceramic filters from clays and rice husk obtained from the far north region of Cameroon (Logone Valley) and their application in potable water treatment. Clays from Mouka were characterized by FTIR analysis. The results showed that the filter formulated with a mixture containing 80% clay and 20% rice husk of 100 μm in size each gave the lowest filter shrinkage rate;these formulated filters were chosen for the remaining work. Leaching tests showed that with filters at a sintering temperature of 830°C the leaching was not observed under neutral (pH 6.8) and acidic (pH 5) conditions as compared to 950°C and 1000°C where the leaching was observed. In basic (pH 9) condition, all the filters obtained released ions. Leaching tests revealed that the conductivity of the leachate for the filters sintered at 830°C was lower than those sintered at 950°C and 1000°C. Meanwhile, conductivity decreases with increasing sintering temperature (temperature up to 830°C) due to the fact that ceramization starts as from 850°C that leads to an amorphous state that favours chemical stability, the leaching ions were Fe2+, Ca2+, Mg2+ and Al3+. The ceramic filters sintered at 950°C were applied to the filtration of water and the performance in terms of turbidity reduction was 95% and the flow rate after 50 minutes was 100 × 10−3 L/h.展开更多
In this paper, the quality of image encryption using filter bank with lifting scheme has been studied and evaluated. Many extensive techniques have been applied to examine the security of the image encryption using th...In this paper, the quality of image encryption using filter bank with lifting scheme has been studied and evaluated. Many extensive techniques have been applied to examine the security of the image encryption using the filter bank cipher with one or two rounds. To analyze and evaluate the proposed scheme, many parameters have been employed, such as, histogram analysis, correlation coefficient, global entropy, block entropy, avalanche effect, number of pixel change rate (NPCR), unified average change intensity (UACI), compression friendliness, exhaustive key analysis, and key sensitivity test. The simulation results showed that, the quality of the image encryption passes all these tests. Moreover, it reaches or excels the current state-of-the-arts. So that, the proposed image encryption process produces random-like output from the statistical point of views.展开更多
In order to realize the real-time and precise test for a weapon system of a certain type of fighter,a signal classification method according to attributes is proposed,common input channels for multiple signals are con...In order to realize the real-time and precise test for a weapon system of a certain type of fighter,a signal classification method according to attributes is proposed,common input channels for multiple signals are configured optimally,and a test adapter and an adaptive signal conditioning module is designed. The hardware of conditioning module can be configured flexibly and the programmable test range can be adjusted owing to programmable multiplexer. An FPGA adaptive filter is designed by the calculated filter coefficient vectors with LMS method to solve the problem of parallel test of fighter weapon system in electromagnetic interference environment. The adaptive signal conditioning technology is characterized by high efficiency,precision and integration. Its application makes the test system successful to conduct real-time and parallel test for a weapon system,which is developed based on VXI bus and virtual-instrument technology.展开更多
为满足地基大口径主焦点式望远镜的多谱段观测需求,对比研究了滤光片切换机构的结构形式。针对传统形式滤光轮机构的缺点,设计了一种沿光轴圆周均布式的新型滤光轮机构,以实现将不同透过谱段的滤光片依次在光路中切入和切出。该滤光轮...为满足地基大口径主焦点式望远镜的多谱段观测需求,对比研究了滤光片切换机构的结构形式。针对传统形式滤光轮机构的缺点,设计了一种沿光轴圆周均布式的新型滤光轮机构,以实现将不同透过谱段的滤光片依次在光路中切入和切出。该滤光轮机构由驱动组件和滤光片组件组成,与传统形式滤光轮机构相比,该机构安装时无需与光轴偏置,充分利用了光轴圆周空间,能够减小对主镜的遮拦。首先,介绍了滤光轮机构的组成及工作原理,并对关键部件进行了选型计算。随后,对滤光轮机构进行了模态分析,其一阶固有频率为108 Hz。最后,对滤光轮机构进行了切换精度测量、滤光片面形精度检测以及高低温试验。检测和试验结果表明,该滤光轮机构的滤光片切入后偏心误差最大为0.1 mm,滤光片面形精度均方根(Root Mean Square,RMS)值均优于λ/30,在系统的工作温度范围内切换顺畅无卡滞。该滤光轮机构能够满足大口径主焦点式望远镜的多谱段观测要求,为滤光轮设计提供了新思路。展开更多
基金Chinese Excellent Youth Science F oundation ( 6992 5 3 0 6) and Aeronautical Foundation Project
文摘An optimized robust filtering algorithm for uncertain discrete-time systemsis presented. To get a series of computational equations, the uncertain part generated by theuncertain systematic matrix in the expression of the error-covariance matrix of time update stateestimation is optimized and the least upper bound of the uncertain part is given. By means of theseresults, the equivalent systematic matrix is obtained and a robust time update algorithm is builtup. On the other hand, uncertain parts generated by the uncertain observation matrix in theexpression of the error-covariance matrix of measurement update state estimation are optimized, andthe largest lower bound of the uncertain part is given. Thus both the time update and measurementupdate algorithms are developed. By means of the matrix inversion formula, the expression structuresof both time update and measurement update algorithms are all simplified. Moreover, the convergencecondition of a robust filter is developed to make the results easy to application. The results offlight data processing show that the method presented in this paper is efficient.
文摘The effectiveness of deep-bed filtration with respect to suspension formed during the preceding processes is evaluated by the test of filterability. The properties and concentration of the suspension being filtered are affected by the efficiency of the preceding aggregation and separation processes. The basic principles of the test of filterability are based on the mechanistic model of filtration. The equations in the mathematical model of the mechanistic conception of filtration are derived from the theory of filtration. The arrangement of the pilot filtration plant for the determination of filterability of flocculent suspension is presented in this paper. The test of filterability is carried out with a thin-layer filter element. The design of a filter element arrangement and its installation are also disclosed in this paper. The inter-dependence of the coefficient of filtration efficiency on the specific volume of intercepted suspensions, filter media grain sizes and different filtration velocities are graphically presented. In addition, the effect of the filter bed clogging resulting from the properties of different suspensions on the head loss generated, the length of filtration cycle and quality of filtrate produced are also shown in this paper.
基金financially supported by Egged Israel Transport Cooperative Society Ltd.
文摘Retrofitting older vehicles with diesel particulate filter（DPF） is a cost-effective measure to quickly and efficiently reduce particulate matter emissions. This study experimentally analyzes real-world performance of buses retrofitted with CRT DPFs. 18 in-use Euro III technology urban and intercity buses were investigated for a period of 12 months. The influence of the DPF and of the vehicle natural aging on buses fuel economy are analyzed and discussed. While the effect of natural deterioration is about 1.2%–1.3%, DPF contribution to fuel economy penalty is found to be 0.6% to 1.8%, depending on the bus type. DPF filtration efficiency is analyzed throughout the study and found to be in average 96% in the size range of 23–560 nm. Four different load and non-load engine operating modes are investigated on their appropriateness for roadworthiness tests. High idle is found to be the most suitable regime for PN diagnostics considering particle number filtration efficiency.
基金Project(2010EME006) supported by Open Fund of the Key Laboratory of Environmental Medicine Engineering of Ministry of Education of China Project(51008063) supported by the National Natural Science Foundation of China+1 种基金 Project(3203000601) supported by the Postdoctoral Key Research Program from Southeast University, China Project(2011BAJ03B05) supported by the National Science and Technology Pillar Program during the 12th Five-Year Plan Period of China
文摘Generation of polydisperse KCl aerosol with a new salt aerosol generator was investigated, Special attention was paid on particles with diameters between 3 and 10 μm. The main improvement consists of the different routes of KCl solution droplets. In traditional generators, the solution droplets travel through one cylinder; while in the case analyzed here, after spray atomization, the droplets travel through two cylinders in series. The first cylinder was fed with warm air and the second one with cold air. In such way, the complete evaporation of the water from the droplets can be ensured. The influencing factors of the generated aerosol size distribution were investigated. The data measured show that the concentration of generated aerosol becomes higher both increasing the flow rate of the KCI solution injected in the first cylinder and increasing the concentration in the solution. The temperature of solution influences mainly the generation of smaller KCI particles （0,3-3 μm）. The amount of hot air used in the generation process increases the concentration of larger KC1 particles （〉3 μm） while cold air does not have the same effect. The aerosol generator is able to generate KC1 aerosol stably. This instrument can be used effectively for testing air filters for automotive.
文摘The accuracy of the HB2 standard model attitude measurement has an important impact on the hypersonic wind tunnel data assessment.The limited size of the model and the existence of external vibrations make it challenging to obtain real-time reliable attitude measurement.To reduce the influence of attitude errors on test results,this paper proposes a Quaternion Nonlinear Complementary Filter(QNCF)attitude determination algorithm based on Microelectromechanical Inertial Measurement Unit(MEMS-IMU).Firstly,the threshold-based PI control strategy is adopted to eliminate noise effect according to the Acceleration Magnitude Detector(AMD).Then,the flexible quaternion method is updated to carry out attitude estimation which is operational and easy to be embedded in the Field Programmable Gate Array(FPGA).Finally,a high-precision three-axis turntable test and a hypersonic wind tunnel test are performed.The results show that the pitchroll attitude errors are within 0.05°and 0.08°in the high-precision three-axis turntable test in a calculation time of 100 s respectively,and the attitude error is within 0.3°after the elastic angle correction in the hypersonic wind tunnel test.The proposed method can provide accurate real-time attitude reference for the analysis of the actual movement of the model,exhibiting certain engineering application value with robustness and simplicity.
基金supported in part by the National Basic Research Program of China(973 Program)under Grant 2013CB336600the Beijing Natural Science Foundation under Grant 4131003+1 种基金the National Natural Science Foundation of China under Grant{61201187,61422109}the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions under Grant YETP0110
文摘In this paper,we investigate the matched filter based spectrum sensing in a more reasonable cognitive radio(CR) scenario when the primary user(PU) has more than one transmit power levels,as regulated in most standards,i.e.,IEEE 802.11 Series,GSM,LTE,LTE-A,etc.This new multiple primary transmit power(MPTP) scenario is specialized by two different targets:detecting the presence of PU and identifying the power level.Compared to the traditional binary sensing where only the presence of PU is checked,SU may attain more information about the primary network(making CR more "intelligent") and design the subsequent optimization strategy.The key technology is the multiple hypothesis testing as opposed to the traditional binary hypothesis testing.We discuss two situations under whether the channel phase is known or not,and we derive the closed form solutions for decision regions and several performance metrics,from which some interesting phenomenons are observed and the related discussions are presented.Numerical examples are provided to corroborate the proposed studies.
基金supported by the China Railway Ministry of Railway's Research and Development Project(Grant No.Z2012-061)
文摘With the fast development of bridge construction in mountainous and seismic areas,it is necessary to conduct related research. Based on the design of a shaking table model test,here are the following test results: the filtering effect exists in soil and is affected by the dynamic constraint conditions,the amplitude is strengthened around the natural frequency and weakened in other frequency bands in the Fourier spectrum. Since the acceleration scaling effect occurred on a sloped surface,the acceleration response decreases from the outside to the inside in soil. The dynamic response is relatively strong near the slip surface in bedrock due to the reflection of seismic waves. The failure mode of landslide is decided by the slope angle and slipping mass distribution, and the test shows the front row stabilizing piles should keep a proper distance from bridge foundation so that seismic resistance can be guaranteed for the bridge foundation.
文摘This paper deals with the characterisation and study of physico-chemical stability of ceramic filters from clays and rice husk obtained from the far north region of Cameroon (Logone Valley) and their application in potable water treatment. Clays from Mouka were characterized by FTIR analysis. The results showed that the filter formulated with a mixture containing 80% clay and 20% rice husk of 100 μm in size each gave the lowest filter shrinkage rate;these formulated filters were chosen for the remaining work. Leaching tests showed that with filters at a sintering temperature of 830°C the leaching was not observed under neutral (pH 6.8) and acidic (pH 5) conditions as compared to 950°C and 1000°C where the leaching was observed. In basic (pH 9) condition, all the filters obtained released ions. Leaching tests revealed that the conductivity of the leachate for the filters sintered at 830°C was lower than those sintered at 950°C and 1000°C. Meanwhile, conductivity decreases with increasing sintering temperature (temperature up to 830°C) due to the fact that ceramization starts as from 850°C that leads to an amorphous state that favours chemical stability, the leaching ions were Fe2+, Ca2+, Mg2+ and Al3+. The ceramic filters sintered at 950°C were applied to the filtration of water and the performance in terms of turbidity reduction was 95% and the flow rate after 50 minutes was 100 × 10−3 L/h.
文摘In this paper, the quality of image encryption using filter bank with lifting scheme has been studied and evaluated. Many extensive techniques have been applied to examine the security of the image encryption using the filter bank cipher with one or two rounds. To analyze and evaluate the proposed scheme, many parameters have been employed, such as, histogram analysis, correlation coefficient, global entropy, block entropy, avalanche effect, number of pixel change rate (NPCR), unified average change intensity (UACI), compression friendliness, exhaustive key analysis, and key sensitivity test. The simulation results showed that, the quality of the image encryption passes all these tests. Moreover, it reaches or excels the current state-of-the-arts. So that, the proposed image encryption process produces random-like output from the statistical point of views.
基金Sponsored by the Key Equipment Research Project of Air Force of China (KJZ06119)
文摘In order to realize the real-time and precise test for a weapon system of a certain type of fighter,a signal classification method according to attributes is proposed,common input channels for multiple signals are configured optimally,and a test adapter and an adaptive signal conditioning module is designed. The hardware of conditioning module can be configured flexibly and the programmable test range can be adjusted owing to programmable multiplexer. An FPGA adaptive filter is designed by the calculated filter coefficient vectors with LMS method to solve the problem of parallel test of fighter weapon system in electromagnetic interference environment. The adaptive signal conditioning technology is characterized by high efficiency,precision and integration. Its application makes the test system successful to conduct real-time and parallel test for a weapon system,which is developed based on VXI bus and virtual-instrument technology.
文摘为满足地基大口径主焦点式望远镜的多谱段观测需求,对比研究了滤光片切换机构的结构形式。针对传统形式滤光轮机构的缺点,设计了一种沿光轴圆周均布式的新型滤光轮机构,以实现将不同透过谱段的滤光片依次在光路中切入和切出。该滤光轮机构由驱动组件和滤光片组件组成,与传统形式滤光轮机构相比,该机构安装时无需与光轴偏置,充分利用了光轴圆周空间,能够减小对主镜的遮拦。首先,介绍了滤光轮机构的组成及工作原理,并对关键部件进行了选型计算。随后,对滤光轮机构进行了模态分析,其一阶固有频率为108 Hz。最后,对滤光轮机构进行了切换精度测量、滤光片面形精度检测以及高低温试验。检测和试验结果表明,该滤光轮机构的滤光片切入后偏心误差最大为0.1 mm,滤光片面形精度均方根(Root Mean Square,RMS)值均优于λ/30,在系统的工作温度范围内切换顺畅无卡滞。该滤光轮机构能够满足大口径主焦点式望远镜的多谱段观测要求,为滤光轮设计提供了新思路。
