Zero-watermark technique,embedding watermark without modifying carriers,has been broadly applied for copyright protection of images.However,there is little research on audio zerowatermark.This paper proposes an audio ...Zero-watermark technique,embedding watermark without modifying carriers,has been broadly applied for copyright protection of images.However,there is little research on audio zerowatermark.This paper proposes an audio zero-watermark scheme based on energy relationship between adjacent audio sections.Taking use of discrete wavelet transformation(DWT),it gets power approximations,or energies,of audio segments.Then,it extracts the audio profile,i.e.the zero-watermark,according to the relative size of energies of consecutive fragments.The experimental results demonstrate that the proposed scheme is robust against general malicious attacks including noise addition,resampling,low-pass filtering,etc.,and this approach effectively solves the contradiction between inaudibility and robustness.展开更多
A new system for measuring low-ohmic standard resistors through a dual current sources bridge is introduced.It is used for low resistance measurements from 1 mΩto 1Ωat 1∶1 ratio,which is suitable for the laboratori...A new system for measuring low-ohmic standard resistors through a dual current sources bridge is introduced.It is used for low resistance measurements from 1 mΩto 1Ωat 1∶1 ratio,which is suitable for the laboratories without cryogenic current comparators(CCC)or direct current comparators(DCC)bridges.Behavior of this bridge is evaluated by comparing its measured values with the unknown resistor values obtained by another method.The accuracy of the introduced bridge is in the level of 10-5 for the 1 mΩresistor,and in the level of 10-4 for the 10 mΩ,100 mΩand 1Ωresistors.Moreover,a dual voltage sources system for the measurement of DC standard resistors from 1 kΩto 100 MΩis also presented.In this system,a modification is made on the modified Wheatstone bridge to evaluate its performance by adding another digital multimeter to measure the ratio between the unknown and the standard resistors simultaneously.This bridge is verified by comparing the measured values of 10 kΩresistor obtained by the two methods with its actual value.The bridge accuracy is in the level of 10-6 except for the 1 kΩresistor,and the bridge asymmetry is also evaluated.It is found the asymmetry is in the level of 10-6 for the resistors from 10 kΩto 100 MΩand in the level of 10-5 for 1 kΩresistors.The introduced bridges operations are controlled by LabVIEW programs designed specially for this purpose,and the expanded uncertainty is also evaluated for all measurement results.展开更多
In this paper, we work on compact quasi-Einstein metrics and prove several gap results. In the first part, we get a gap estimate for the first nonzero eigenvalue of the weighted Laplacian, by establishing a comparison...In this paper, we work on compact quasi-Einstein metrics and prove several gap results. In the first part, we get a gap estimate for the first nonzero eigenvalue of the weighted Laplacian, by establishing a comparison theorem for the weighted heat kernel. In the second part, we establish two gap results for the Ricci curvature and the scalar curvature, based on which some rigid properties can be derived.展开更多
基金This work is supported by the National Natural Science Foundation of China under Grant No. 61170269, No. 61170272, No. 61202082, Beijing Natural Science Foundation under Grant No. 4122026, the Fundamental Research Funds for the Central Universities under Grant No. BUPT2013RC0308, No. BUPT2013RC0311, and Scientific Research Common Program of Beijing Municipal Commission of Education under Grant No. KM201210015007, KM201210015006.
文摘Zero-watermark technique,embedding watermark without modifying carriers,has been broadly applied for copyright protection of images.However,there is little research on audio zerowatermark.This paper proposes an audio zero-watermark scheme based on energy relationship between adjacent audio sections.Taking use of discrete wavelet transformation(DWT),it gets power approximations,or energies,of audio segments.Then,it extracts the audio profile,i.e.the zero-watermark,according to the relative size of energies of consecutive fragments.The experimental results demonstrate that the proposed scheme is robust against general malicious attacks including noise addition,resampling,low-pass filtering,etc.,and this approach effectively solves the contradiction between inaudibility and robustness.
文摘A new system for measuring low-ohmic standard resistors through a dual current sources bridge is introduced.It is used for low resistance measurements from 1 mΩto 1Ωat 1∶1 ratio,which is suitable for the laboratories without cryogenic current comparators(CCC)or direct current comparators(DCC)bridges.Behavior of this bridge is evaluated by comparing its measured values with the unknown resistor values obtained by another method.The accuracy of the introduced bridge is in the level of 10-5 for the 1 mΩresistor,and in the level of 10-4 for the 10 mΩ,100 mΩand 1Ωresistors.Moreover,a dual voltage sources system for the measurement of DC standard resistors from 1 kΩto 100 MΩis also presented.In this system,a modification is made on the modified Wheatstone bridge to evaluate its performance by adding another digital multimeter to measure the ratio between the unknown and the standard resistors simultaneously.This bridge is verified by comparing the measured values of 10 kΩresistor obtained by the two methods with its actual value.The bridge accuracy is in the level of 10-6 except for the 1 kΩresistor,and the bridge asymmetry is also evaluated.It is found the asymmetry is in the level of 10-6 for the resistors from 10 kΩto 100 MΩand in the level of 10-5 for 1 kΩresistors.The introduced bridges operations are controlled by LabVIEW programs designed specially for this purpose,and the expanded uncertainty is also evaluated for all measurement results.
基金supported by Natural Science Foundation of Jiangsu Province (Grant No. BK20141235)
文摘In this paper, we work on compact quasi-Einstein metrics and prove several gap results. In the first part, we get a gap estimate for the first nonzero eigenvalue of the weighted Laplacian, by establishing a comparison theorem for the weighted heat kernel. In the second part, we establish two gap results for the Ricci curvature and the scalar curvature, based on which some rigid properties can be derived.
