404 research outputs found
On coherence of quantum operations by using Choi-Jamio{\l}kowski isomorphism
In quantum information, most information processing processes involve quantum
channels. One manifestation of a quantum channel is quantum operation acting on
quantum states. The coherence of quantum operations can be considered as a
quantum resource, which can be exploited to perform certain quantum tasks. From
the viewpoint of Choi-Jamio{\l}kowski isomorphism, we study the coherence of
quantum operations in the framework of resource theory. We define the phase-out
superoperation and give the operation which transforms the Choi-Jamio{\l}kowski
state of a quantum operation to the Choi-Jamio{\l}kowski state of the another
quantum operation obtained by using the phase-out superoperation to act on the
quantum operation. The set of maximally incoherent superoperations, the set of
nonactivating coherent superoperations and the set of de-phase incoherent
superoperations are defined and we prove that these sets are closed to compound
operation and convex combination of quantum superoperations. Further, we
introduce the fidelity coherence measure of quantum operations and obtain the
exact form of the fidelity coherence measure of the unitary operations on the
single qubit.Comment: 10 pages, no figur
An Algorithm for Idle-State Detection in Motor-Imagery-Based Brain-Computer Interface
For a robust brain-computer interface (BCI) system based on motor imagery (MI), it should be able to tell when the subject is not concentrating on MI tasks (the “idle state”) so that real MI tasks could be extracted accurately. Moreover, because of the diversity of idle state, detecting idle state without training samples is as important as classifying MI tasks. In this paper, we propose an algorithm for solving this problem. A three-class classifier was constructed by combining two two-class classifiers, one specified for idle-state detection and the other for these two MI tasks. Common spatial subspace decomposition (CSSD) was used to extract the features of event-related desynchronization (ERD) in two motor imagery tasks. Then Fisher discriminant analysis (FDA) was employed in the design of two two-class classifiers for completion of detecting each task, respectively. The algorithm successfully provided a way to solve the problem of “idle-state detection without training samples.” The algorithm was applied to the dataset IVc from BCI competition III. A final result with mean square error of 0.30 was obtained on the testing set. This is the winning algorithm in BCI competition III. In addition, the algorithm was also validated by applying to the EEG data of an MI experiment including “idle” task
Novel Wavelet Threshold Denoising Method in Axle Press-Fit Zone Ultrasonic Detection
Axles are important part of railway locomotives and vehicles. Periodic ultrasonic inspection of axles can effectively detect and monitor axle fatigue cracks. However, in the axle press-fit zone, the complex interface contact condition reduces the signal-noise ratio (SNR). Therefore, the probability of false positives and false negatives increases. In this work, a novel wavelet threshold function is created to remove noise and suppress press-fit interface echoes in axle ultrasonic defect detection. The exponential threshold function proposed by Andria [1] can\u27t get a gradual curve for later optimum searching process; and the novel wavelet threshold function with two variables is designed to ensure the precision of optimum searching process. Based on the positive correlation between the correlation coefficient and SNR [2] and with the experiment phenomenon that the defect and the press-fit interface echo have different axle-circumferential correlation characteristics, a discrete optimum searching process for two undetermined variables in novel wavelet threshold function is conducted. The performance of the proposed method is assessed by comparing it with traditional threshold methods using real data. The statistic results of the amplitude and the peak SNR of defect echoes show that the proposed wavelet threshold denoising method not only maintains the amplitude of defect echoes but also has a higher peak SNR
STUDY ON EXTRACTION PROCESS OF TANNINS FROM SEMEN CUSCUTAE AND THEIR ANTI-PAPILLOMA ACTIVITY
The objective of this paper was to study the extraction methods of tannin constituents from Semen Cuscutae and their anti-papilloma effects. Single factor test and orthogonal design methods were used to determine the optimal extraction method; the mouse skin papilloma model induced by DMBA/croton oil was established, which was a classic two-stage carcinogenesis model being used to observe and evaluate the anti-carcinogenic effects of tannins extracted from Semen Cuscutae in different stages. The optimal extraction method of Semen Cuscutae was a 20-fold volume of solvent, a temperature of 50 oC, three times of extraction, with 20 min each, skin papilloma experiment revealed that the number of bearing tumors gradually reduced, and the inhibition rate gradually increased with the increase of dose, in the high-dose group, its inhibition rate reached 70.2%. Tannin extract from Semen Cuscutae has an obvious inhibitory effect on skin papilloma development
ANTI-INFLAMMATORY AND ANALGESIC ACTIVITY OF R.A.P. (RADIX ANGELICAE PUBESCENTIS) ETHANOL EXTRACTS
The objective of this paper was to study the anti-inflammatory and analgesic effects of Radix Angelicae Pubescentis (R.A.P) ethanol extracts. Three classic anti-inflammatory models and two analgesic models were used in this research. In anti-inflammatory tests, all the extracts have a certain inhibition on the acute inflammation induced by xylene, however, 60% ethanol extract significantly inhibited the inflammation in the three models. In analgesic experiment, compared with the blank control group, the comparisons between R.A.P. groups and control group had significant difference (p﹤0.01). The incubation period in mouse writhing test or the tail-curl immersion tests could be extended greatly
The Early Stage Wheel Fatigue Crack Detection Using Eddy Current Pulsed Thermography
The in-service wheel-set quality is one of critical challenges for railway safety, especially for the high-speed train. The defect in wheel tread, initiated by rolling contact fatigue (RCF) damage, is one of the most significant phenomena and has serious influence on rail industry. Eddy current pulsed thermography (ECPT) is studied to compensate the Ultrasonic Testing (UT) method for detection these early stage of fatigue cracks in wheel tread. This paper proposes several induction coils, such as linear coil, Yoke coil and Helmholtz coils, based ECPT method to meet the imaging of multiple cracks and irregular surface in wheel tread through numerical simulation and experimental results. Some features are extracted and studied also to quantify the fatigue crack in term of UT and ECPT. The proposed method greatly enhances the capability for cracks detection and quantitative evaluation compared with previous Non-Destructive Testing (NDT) method in railway
High-performance cVEP-BCI under minimal calibration
The ultimate goal of brain-computer interfaces (BCIs) based on visual
modulation paradigms is to achieve high-speed performance without the burden of
extensive calibration. Code-modulated visual evoked potential-based BCIs
(cVEP-BCIs) modulated by broadband white noise (WN) offer various advantages,
including increased communication speed, expanded encoding target capabilities,
and enhanced coding flexibility. However, the complexity of the
spatial-temporal patterns under broadband stimuli necessitates extensive
calibration for effective target identification in cVEP-BCIs. Consequently, the
information transfer rate (ITR) of cVEP-BCI under limited calibration usually
stays around 100 bits per minute (bpm), significantly lagging behind
state-of-the-art steady-state visual evoked potential-based BCIs (SSVEP-BCIs),
which achieve rates above 200 bpm. To enhance the performance of cVEP-BCIs with
minimal calibration, we devised an efficient calibration stage involving a
brief single-target flickering, lasting less than a minute, to extract
generalizable spatial-temporal patterns. Leveraging the calibration data, we
developed two complementary methods to construct cVEP temporal patterns: the
linear modeling method based on the stimulus sequence and the transfer learning
techniques using cross-subject data. As a result, we achieved the highest ITR
of 250 bpm under a minute of calibration, which has been shown to be comparable
to the state-of-the-art SSVEP paradigms. In summary, our work significantly
improved the cVEP performance under few-shot learning, which is expected to
expand the practicality and usability of cVEP-BCIs.Comment: 35 pages, 5 figure
- …