A Fast Multilevel Fuzzy Transform Image Compression Method

We present a fast algorithm that improves on the performance of the multilevel fuzzy transform image compression method. The multilevel F-transform (for short, MF-tr) algorithm is an image compression method based on fuzzy transforms that, compared to the classic fuzzy transform (F-transform) image compression method, has the advantage of being able to reconstruct an image with the required quality. However, this method can be computationally expensive in terms of execution time since, based on the compression ratio used, different iterations may be necessary in order to reconstruct the image with the required quality. To solve this problem, we propose a fast variation of the multilevel F-transform algorithm in which the optimal compression ratio is found in order to reconstruct the image in as few iterations as possible. Comparison tests show that our method reconstructs the image in at most half of the CPU time used by the MF-tr algorithm.

Influence of backstreaming ions on spot size of 2 MeV electron beam

Influence of backstreaming ions from the target on spot size of focused 2 MeV electron beam was considered. The 2D version of the particle-in-cell code KARAT was used to study the formation of the ions stream and dynamics of the electron beam. It was shown that light species emitted from the target can disrupt the beam. The emission of low-ionized states of tantalum cannot disrupt the beam during about 30 ns or longer. A few non-invasive techniques of mitigation of the beam disruption were considered. Final magnetic lens with fast variation of magnetic field of several hundred Ampere-turns per nanosecond is capable to stabilize initial spot size of the compressed beam at the target.

HIGH FREQUENCY ELECTRICAL OSCILLATIONS IN CAVITIES

If the interior of a conducting cavity (such as a capacitor or a coaxial cable) is supplied with a very high-frequency electric signal, the information between the walls propagates with an appreciable delay, due to the _niteness of the speed of light. The con_guration is typical of cavities having size larger than the wavelength of the injected signal. Such a non rare situation, in practice, may cause a break down of the performances of the device. We show that the classical Coulomb's law and Maxwell's equations do not correctly predict this behavior. Therefore, we provide an extension of the modeling equations that allows for a more reliable determination of the electromagnetic _eld during the evolution process. The main issue is that, even in vacuum (no dielectric inside the device), the fast variation of the signal produces sinks and sources in the electric _eld, giving rise to zones where the divergence is not zero. These regions are well balanced, so that their average in the domain is zero. However, this behavior escapes the usual treatment with classical electromagnetism.

Research on SQL injection detection technology based on SVM

SQL injection, which has the characteristics of great harm and fast variation, has always ranked the top of the OWASP TOP 10, which has always been a hot spot in the research of web security. In view of the difficulty of detecting unknown attacks by the existing rule matching method, a method of SQL injection detection based on machine learning is proposed. And the author analyses the method of SQL injection feature extraction, f Finally, the word2vec method is selected to process the text data of the HTTP request, which can effectively represent the SQL injection features containing the attack payload. Training and classification of processed samples with SVM algorithm, The experiment shows that this method effectively solves the problem of SQL injection to the mutation and the high leakage rate of the rule matching. By comparing with the classification results of statistical features, this SQL injection classification model has a higher detection rate.

A CFD Study with Fuzzy Logic Pitch Angle Turbine Control Implementation for OWC Generation System

The paper takes the improvement of the performance for an OWC converter from the mechanical side. A FEM model of the OWC conversion structure was proposed, studied and simulated using a CFD simulator. A novel wave generation method was applied through the RWMD method (Real Wave Model Simulator) instead of using an ordinary sin wave generator on the tank to make the waves the closest possible to the real sea waves. A mechanical prototype was built for this purpose to get an oscillated wave model. On the electrical side, a pitch angle control system based on fuzzy set was applied on the turbine to be auto-adapted for the fast variation of the airflow speed to establish and maximize the extracted power from the OWC device. The model have been studied, simulated, implemented and tested to validate the obtained results.

Research on a New Control Strategy of Multi-Energy Complementary Isolated Power System

Aiming at a kind of multi-energy complementary isolated power system in Tibet ali area, which consists of photovoltaic (PV) station with storage device, hydro generator, and diesel generator, a new control strategy was presented. According to the power system characteristics, analyzed the new control strategy, it can realize the grid power output with zero steady-state error. In the DIgSILENT/PowerFactory simulation environment, building the multi-energy complementary isolated power system model and simulation based on the control strategy, the system can track the fast variation of the PV array output power or other output power. Two studied cases verify the control strategy.

A New Improved Perturbation and Observation MPPT Control Algorithm in Photovoltaic System

The conventional perturbation and observation (P&O) method is combined by the target tracking technique of data fusion, the adaptive multi-mode MPPT control algorithm is put forward for the first time. The reasonable and long step is selected to insure tracking velocity, the target tracking algorithm is adoptted for weaken and restrain vibration, the target maneuvering detection technique is put to use to judge whether the system is “lose control ” in fast variation environments, the repeat starting up perturbation and observation (P&O) method in order to strengthen system stability .The experimental result shows the correctness and validity of the method.