Search

Chaotic systems are often used as random sequence generators due to their excellent pseudo-randomness, but there is limitation that the discretization of complex chaotic systems requires a long computational time. Therefore, a parallel discretization method for chaotic system, and an accelerated chaotic image secure communication system based on the Zynq-7000 platform are proposed in this paper. Firstly, a 3-dimensional (3-D) chaotic system is constructed to generate random sequence, which has high Shannon entropy (SE) complexity. Then, chaotic system is parallelly discretized through finite state machine, which sequences are combined with scrambling and diffusion algorithms to construct an accelerated chaotic image secure communication system. Finally, the secure communication process based on the Zynq-7000 platform is completed, and the analysis of hardware experimental results shows that the system has safe performances, simple structure and excellent operational efficiency. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOC) have been proven to cause considerable harm to both the ecological environment and human health. Anthropogenic VOC emissions are primarily generated by the industrial sector. The utilization of porous carbon as an adsorbent has emerged as an effective method for the efficient removal of VOC from industrial sources. However, during the actual production processes, VOC exhaust gases are often mixed with water vapor, which poses challenges for adsorption purification. This review provides a comprehensive overview of the remarkable advancements in various carbon materials in terms of their ability to adsorb both VOC and water vapor. Additionally, it systematically summarizes the influence of surface groups on adsorbents and the molecular properties of VOC on their adsorption by carbon materials. Furthermore, this review introduces the mechanism underlying adsorption-adsorbent interactions and discusses the construction of models for adsorbing water vapor and VOC. The challenges associated with the application of carbon materials for VOC adsorption in humid environments are also addressed. This review aims to offer theoretical and technical guidance for the effective purification of moist VOC waste gases emitted from industrial sources, thereby achieving precise control of VOC emissions. [ABSTRACT FROM AUTHOR]

In this paper, a combination of theoretical modeling, finite element simulation, and experimental methods is employed to investigate the forming mechanism and evolutionary pattern of the stagnant region during mechanical scratching with a diamond wedge tool. The study is structured as follows: Firstly, a theoretical calculation model for the geometric parameters of the stagnant region on the formed groove surface is established based on the contact friction partition mechanism and slip-line field theory. The model indicates that the geometric parameters lB-sg, lV-sg, and ∆lsg of the stagnant region are determined by the length of the stagnant region lp-sg in the plastic flow plane and the transformation parameters. Secondly, the formation process of the stagnant region in mechanical scratching is investigated using an orthogonal cutting simulation model with a negative rake angle tool. The results reveal that the stagnant region is a plastic deformation region formed due to the geometrical characteristics of the negative front surface of the scratching tool and its excessive extrusion, which leads to the formation of adhesive friction within the material. Thirdly, the characteristics of the stagnant region are determined through scratching experiments. Compared to the material in the plastic flow region, the material within the stagnant region exhibits finer and denser microstructures, reduced surface hardening peaks and hardened layer depths, and significantly improved surface roughness. Finally, the evolutionary pattern of the stagnant region under the influence of scratching processing parameters is examined based on the theoretical calculation model of the geometric parameters and the scratching experiment. The findings indicate that as the wedge angle of the scratching tool decreases, the relief angle increases, the absolute value of the rotation angle around the Y-axis decreases, the scratching speed decreases, and the material's plastic adherence improves, the PI/k value decreases, the lp-sg value increases, and consequently, the geometric parameters lB-sg, lV-sg, and ∆lsg of the stagnant region on the formed groove surface also increase. The deviation analysis of the geometric parameters of the stagnant region reveals a consistent trend between the theoretical and experimental values of lV-sg and ∆lsg, with maximum deviations of 15 μm and 4.13%, respectively. This study provides theoretical and experimental evidence for the establishment of the theoretical model of the stagnant region in mechanical scratching, the analysis of its forming mechanism, and the control of the stagnant region geometric parameters on the formed groove surface. [ABSTRACT FROM AUTHOR]

In order to identify the time-varying frequency and amplitude of structural vibration based on the bridge structural health monitoring data and obtain the cable force of cable-stayed bridges in real time, a spectrum analysis method based on amplitude and phase estimation (APES) was proposed in this study. The amplitude spectrum of the acceleration data is first calculated by the APES method, the real-time spectrogram of the cable is obtained by the sliding window method. Then the modal frequency and amplitude are automatically extracted from the real-time spectrum by using a frequency extrusion post-processing technique, which can be regarded as the average value of the instantaneous frequency and amplitude respectively. Next, the fundamental frequency of the cable is extracted by using an automatic identification method, and the performance of the proposed method is verified. Finally, real-time scoring of cable forces and structural condition assessment is achieved with consideration of the moderation index model as well as the material strength. The results show that the APES method can use shorter calculation samples than the traditional Fast Fourier Transform (FFT) to obtain higher resolution and more accurate amplitude, which provides a theoretical basis for the real-time identification of fundamental frequency based on short-term monitoring data. The frequency extrusion post-processing-algorithm can reduce the spectrum recognition delay and improve timeliness of the cable force evaluation. The time-varying cable force with an interval of 10 s can be used to reflect the health status of the cable in time. The research results can provide technical support for the real-time extraction of cable force of long-span cable-stayed bridges, and can also provide an effective basis for component condition evaluation and bridge maintenance decision-making. [ABSTRACT FROM AUTHOR]

The editorial in "Lasers in Medical Science" discusses the successful treatment of Becker's Nevus using a combination of continuous low-fluence Q-switched Nd: YAG 1064 nm laser and long-pulsed Nd: YAG 1064 nm laser. Two cases are presented, showing significant improvement in pigmentation and hair removal with minimal adverse effects. The treatment approach offers a novel and effective option for patients with Becker's Nevus resistant to traditional laser therapies, providing promising results and high patient satisfaction levels. The study was supported by grants from the Shandong Provincial Natural Science Foundation. [Extracted from the article]

In order to improve the performance of sliding mode observer in detecting the state of induction motor, a state detection method based on particle swarm optimization (PSO)-backstepping (BS)-sliding mode observer (SMO) is proposed in this paper. In this method, the controller is constructed and the parameters of the control rate are optimized, so that the tracking accuracy and robustness of the new observer are improved relative to conventional observer, exponential observer, PI and PID. Firstly, the state equation of the induction motor under stator and rotor winding fault and stator current sensor fault is established. Secondly, the new sliding mode observer is designed using the backstepping method based on the new reaching law. Then, the new fitness function and PSO is used to optimize the parameters of the new sliding mode observer. Finally, the simulation comparison experiment of stator current state detection is carried out under the simulated fault condition of induction motor. The feasibility of the method is verified by comparing the state tracking situation and the state detection error. The comparative experimental results show that the method has less jitter, stronger robustness, and higher state tracking accuracy when detecting stator current states under different faults. [ABSTRACT FROM AUTHOR]

Stochastic resonance (SR) is a method to enhance weak characteristic signals, but the classical model like Duffing oscillation is limited by fewer parameters when it is applied to detect different signals. Consider chaotic system with the characteristics of adjustable parameters and wide dimensions, from the perspective of chaos to induce SR, which is studied to discover the conversion conditions between chaos and SR system. Firstly, the mechanism of a class of Lorenz-like SR system for SR generation is studied, whose parameters relationship meeting the moving point transition and parameters range satisfying the maximum Lyapunov exponent (MLE) are analyzed. Secondly, within the determined parameters range, the optimal parameters are searched by particle swarm optimization (PSO) to output signal with optimal signal-to-noise ratio (SNR). Finally, the output fault signal after highlighting the characteristics is diagnosed by utilizing extreme learning machine (ELM). The experimental results show that the fault signal is detected and diagnosed efficiently and accurately. [ABSTRACT FROM AUTHOR]

In order to detect the fault of induction motor quickly and accurately, a new fault detection method based on backstepping sliding mode observer is proposed in this paper. The new sliding mode observer has good robustness to unknown load disturbance, can effectively weaken the chattering phenomenon, and has better response speed and stability than exponential and traditional observers. Firstly, the backstepping controller is designed according to the mathematical model of induction motor. Secondly, based on the backstepping method, the sliding mode control is introduced, and a new reaching law sliding mode observer is designed to estimate the stator current and speed. After comparing the actual value with the observed value, the self-detection of induction motor fault is realized. Then, the Simulink model under different fault conditions is established to simulate the three faults of stator winding fault, rotor winding fault and simultaneous fault of stator and rotor winding. The comparative experimental results show that the new sliding mode observer based on backstepping can accurately and sensitively detect different types of early micro faults, which has a certain reference value for the engineering application of fault detection. [ABSTRACT FROM AUTHOR]

Convolutional neural networks (CNNs) have greatly promoted the development of artificial intelligence. In general, CNNs with high performance are over-parameterized, requiring massive calculations to process and predict the data. It leads CNNs unable to apply to exiting resource-limited intelligence devices. In this paper, we propose an efficient model compression framework based on knowledge distillation to train a compact student network by a large teacher network. Our key point is to introduce a positive-unlabeled (PU) classifier to promote the compressed student network to learn the features of the prominent teacher network as much as possible. During the training, the PU classifier is to discriminate the features of the teacher network as high-quality and discriminate the features of the student network as low-quality. Simultaneously, the student network learns knowledge from the teacher network through the soft-targets and attention features. Extensive experimental evaluations on four benchmark image classification datasets show that our method outperforms the prior works with a large margin at the same parameters and calculations cost. When selecting the VGGNet19 as the teacher network to train on the CIFAR dataset, the student network VGGNet13 achieves 94.47% and 75.73% accuracy on the CIFAR-10 and CIFAR-100 datasets, which improved 1.02% and 2.44%, respectively. [ABSTRACT FROM AUTHOR]

In order to accurately track the state of the doubly fed induction generator (DFIG) for wind power systems and implement its fault detection, an event-triggered sliding mode observer based on particle swarm optimization (PSO-ET-SMO) is proposed in this paper. First, the sliding mode observer (SMO) is designed according to the rotor current state space equation of the DFIG. Then, a new event-triggered mechanism (NETM) is proposed for the designed SMO, and the constructed fitness function is optimized by using Particle Swarm Optimization (PSO) algorithm, so as to obtain the optimal parameters of the SMO. Finally, to verify the effectiveness of the proposed method in this paper, the fault detection of the DFIG for wind power systems is performed by using the sequence of residuals between the rotor current output values and the sliding mode observations. The innovation of this work is that a NETM is designed by combining sliding mode reaching law, and this mechanism is introduced into the design of SMO. The simulation results show that the proposed method not only reduces sliding mode chattering, but also improves the tracking effect of SMO and detects faults accurately. At the same time, due to the action of the NETM, the transmission burden between the SMO and the DFIG is also reduced. [ABSTRACT FROM AUTHOR]

Traditional fault recognition algorithms can only identify the known classes of fault in wind turbine systems(WTs). These faults have already appearedin the WTs, thus, the fault recognition algorithm can identify the classesof them. However, if a new classfault didnot happen in the WTs before, the traditional fault recognition algorithm can only identify it as known class of fault, which results in an incorrect identification. Toaddress this problem, a new class fault recognition method based on semi-supervised deep learning(SDL-NCFR)is proposed. Firstly, multiple WTs signals are used as input and features are extracted by convolutional autoencoder network; secondly, the initialization model is built with compressed features as input to the classifier and error feature map as input to the detector; finally, the detector will put new class fault instances into the buffer. When the buffer overflows, the algorithm starts to update, thus achieving the purpose of identifying new class faults. The experimental results show that the average accuracy of the initialized model could reach more than 98%. The accuracy of updated model could still reach 89.39%, and the detection rate could reach 99.50%, the recall reached 88.76%, the precision reached 92.03%, and the F1 score reached 90.36% respectively. The experimental results show that the proposed algorithm can effectively solve the problem of identifying new class faults in WTs, and the accuracy is much higher than that of traditional detection methods. [ABSTRACT FROM AUTHOR]

The movement presented by chaos is violent oscillation, making the system unstable, which often is harmful in engineering. Therefore, how to suppress chaotic state quickly is a research hotspot in the field of control. Compared with integer-order system, fractional-order chaotic system has more complex dynamic characteristics, and it is often difficult to control the dynamic system into a stable periodic motion. In this paper, a new sliding mode controller was proposed after newly constructing a fractional-order chaotic system, to make the chaotic system enter a predetermined motion state quickly and maintain stability. Firstly, a new five-dimensional fractional-order chaotic system was constructed, analyzing its dynamic characteristics through the 0–1 test. Then, a sliding mode controller was designed, with proved stability to regulate the motion state of chaotic system. Finally, the circuit realization and control process simulation of the five-dimensional fractional-order chaotic system were carried out. The experimental results show that the proposed sliding mode controller has simple structure, but fast response and excellent control effect. [ABSTRACT FROM AUTHOR]

In this paper, a five-dimensional hyperchaotic system for secure communication based on MCU is proposed. First, a five-dimensional hyperchaotic system is constructed and the features such as equilibrium stability and Lyapunov exponents are analyzed. The states of this system with different parameters are studied, including periodic, hyperchaotic and chaotic state. Next, the complexity of system is analyzed. By analyzing the complexity of each dimension, the correctness of system selection is verified and the dimension with the highest complexity is selected for communication encryption. Then, the hardware circuit is designed. The encryption and decryption of square wave signal are completed through simulation which realizing the secure communication. Finally, the accuracy of system and the algorithm of realizing chaos of MCU are adjusted, and the system after adjustment is in a chaotic state verified by 0–1 test, the chaos is successfully generated by MCU. Using MCU can reduce the hardware cost of signal encryption greatly, and apply five-dimensional hyperchaotic system to secure communication can not only improve the security but also enhance the anti-interference ability in the process of signal transmission. [ABSTRACT FROM AUTHOR]

This paper presented a novel six-dimensional hyperchaotic system and constructed a new chaotic communication encryption method to take advantage of every dimensional sequence of the system. Based on the existing four-dimensional Lorenz system, a new six-dimensional hyperchaotic system is proposed and some related dynamic characteristics of the system are analyzed. To improve the security of communication, the signals are decomposed into n groups of linearly independent data, and the n groups of data are linked with n-dimensional sequence s of the system. A circuit simulation experiment is performed to verify the effectiveness of the method. The experimental results show that combining n groups of linearly independent data with n-dimensional chaotic sequences increases the utilization of chaotic sequences and improves the security of secure communication. [ABSTRACT FROM AUTHOR]

This paper proposes a novel seven-dimensional fractional-order chaotic system applied to secure communication. First, a seven-dimensional fractional order system is constructed by selecting an arbitrary fractional order q. Then, the chaotic and non-chaotic dynamic behaviors of the system are analyzed by 0–1 Test, and the correctness is verified by phase diagram comparison and complexity analysis. Then, the corresponding fractional-order chaotic circuit is designed, and the phase image which is basically consistent with the experimental simulation results is obtained. Finally, the seven-dimensional fractional-order chaotic system is used to complete the signal encryption and decryption test to achieve secure communication. This indicates that the seven-dimensional fractional-order chaotic system proposed to this paper has more complex dynamic characteristics and can be used for secure communication. [ABSTRACT FROM AUTHOR]

Port-wine stains (PWS) affect 0.3 to 0.5% of newborns and pulsed dye laser (PDL) remains the treatment of choice. However, no reliable study regarding the benefits of more frequent has been conducted. We designed the present study to evaluate whether more frequent PDL treatments in infantile patients would achieve further lightening of erythema. We prospectively investigated 20 infants with PWS. Two adjacent sites were both treated for a 12-week duration and randomly allocated to be treated for seven sessions at 2-week intervals or three sessions at 6-week intervals. The efficacy outcome 2 months after the final treatment was determined by visual and chromameter evaluation. Sixteen patients completed the study with a total of 54 treatment sites. Similar results were observed in the two groups. The average blanching rates were 42.93% (SD = 27.92%) and 43.81% (SD = 32.80%) for PDL treatments with seven and three sessions, respectively (p = 0.374). Partial recovery from the laser treatment was more frequently observed and side effects were significantly higher at 2-week follow-ups (p < 0.001), resulting in a total of 3-13 weeks for skin recovery. More frequent PDL treatments do not necessarily increase efficacy in infantile PWS patients. Considering the potential risks and added costs, this practice may not be of benefit. (Clinical trial registration number: ChiCTR-ONC-17010857). [ABSTRACT FROM AUTHOR]

EMLA cream was developed to reduce pain during pulsed-dye laser (PDL) treatment; however, no standard assessment for the therapeutic outcomes of PDL with EMLA creams thus far available. This comparative, prospective clinical trial evaluates laser efficacy and pain reduction during PDL treatment with EMLA cream for local topical anesthesia. Nineteen patients with untreated port-wine stain (PWS) were treated using PDL and examined in this study. Treatment specifications included Vbeam® PDL (Candela Corp.), 595-nm wavelength, 9 J/cm2 radiant exposure, 0.45 ms pulse duration, 10 mm spot size, and cryogen spray cooling (40 ms cooling plus a 20 ms delay). A topical anesthetic (EMLA cream: 2.5% lidocaine and 2.5% prilocaine) and a placebo were applied to two respective testing areas on all patients prior to treatment. The visual analog scale (VAS) was used for pain assessment. Clinical therapeutic outcomes were evaluated by visual evaluation and with the use of a chromameter 2 months after 3PDL treatments. The average VAS scores were 3.15 ± 0.95 and 8 ± 0.57 for the EMLA cream site and the placebo site, respectively, at a significance level p < 0.001. The EMLA cream site and the placebo site had clearance or fading rates of 45.08 and 44.12%, respectively (p < 0.05). No serious side effects were reported. Patients reported a consistent decrease in pain during PDL treatment when the topical anesthetic EMLA cream was administered. Treatment of PWS by PDL with EMLA cream does not lead to a decrease in efficacy or an increase in side effects; instead, it significantly reduces pain during treatment. EMLA cream is a safe and effective local topical anesthetic for PWS treatment by PDL. [ABSTRACT FROM AUTHOR]

Diagnosis and monitoring of early high-flow vascular malformations could be a meaningful pursuit. However, there has been no ideal method for their long-term monitoring and prognosis. We examined 21 early high-flow vascular malformations in this study and deemed that high-frequency color Doppler ultrasound could be regarded as the first diagnostic and monitoring choice for early high-flow vascular malformations at present. [ABSTRACT FROM AUTHOR]

Developing fault detection is very important for improving the equipment reliability and saving energy consumption. As compared with neural networks, extreme learning machine (ELM) is based on statistical learning theory, which has advantages of better classification ability and generalization performance. This paper presents a novel approach for fault detection and diagnosis based on Firefly-Chaos Algorithm and Extreme Learning Machine. The experiment result indicates this proposed method is effective for Analog Circuit fault detection and diagnosis and the model generalization ability is favorable. [ABSTRACT FROM AUTHOR]

A new three-dimensional autonomous chaotic system is proposed in this paper. It analyzes dynamic behaviors of this new system, including the stability of equilibria, the system dissipativity, poincare maps, Lyapunov exponent, bifurcation, wave forms, and spectrum. Numeral simulation is performed in Matlab. A chaotic circuit is designed, and the corresponding circuit simulation is conducted. The results show that the chaotic attractor exists in the new system. The synchronization problem of the chaotic system is solved with a synchronization method, and its synchronization circuit is designed. Numeral simulation and circuit simulation show that the synchronization problem of this chaotic system proposed is solved. [ABSTRACT FROM AUTHOR]

In this paper, we present a new recursive method to compute higher order sensitivities of node voltages, as well as those of circuit performances (gain, input and output impedances, or reflection coefficients) with respect to all circuit parameters. Using the sensitivity coefficients we formulate multivariate polynomial equations. Fault identification is obtained by solving these equations with respect to element deviations. This task can be accomplished by using a multivariable Newton-Raphson procedure (mNR) for solving nonlinear multivariable equations. [ABSTRACT FROM AUTHOR]

In 2011, four H3N2 swine influenza viruses (SIVs) were isolated from nasal swabs of four pigs (800 nasal swabs were collected from pigs showing influenza-like symptoms) in Guangdong province, China. Four different genotypes of H3N2 appeared among pigs in southern China, including wholly human-like H3N2 viruses, intermediate (1975) double-reassortant human H3N2 viruses (resulting from reassortment between an early human lineage and a recent human lineage), recent double-reassortant human H3N2 viruses, and avian-like H3N2 viruses. Because pigs can support the reassortment of human and avian influenza viruses, our surveillance should be enhanced as a part of an overall pandemic preparedness plan. [ABSTRACT FROM AUTHOR]

This paper presents a novel procedure for analog implementation of wavelet transform in switched-current (SI) circuits. An improved hybrid PSO-SQP optimization is employed to precisely approximate the impulse response of a filter to the wavelet base function in time domain. The SI first- and second-order section circuits with minimum coefficients are designed based on infinite-impulse-response digital filter technology. Cascode techniques are occupied to reduce the effects of parasitic elements. Based on these SI first- and second-order section circuits, a parallel wavelet circuit structure is presented to synthesize the approximated wavelet base function. By adjusting the switch clock frequency, the wavelets at different scales can be realized. The Gaussian wavelet is selected as an example to illustrate the design procedure. Simulation results demonstrate the feasibility of the proposed procedure for analog wavelet transform in SI circuits. [ABSTRACT FROM AUTHOR]