Abstract:In order to improve the performance of the Internet of Things (IOT) network intrusion detection model, Residual Networks (ResNet) and bidirectional Long-Short Term Memory (LSTM) networks were combined，and an IOT intrusion detection classification model was constructed. For the rapid and batch processing problem of large-scale IOT traffic, multiple traffic samples were converted into grayscale images. Then，the grayscale images were used to construct IOT intrusion detection and classification model which combined with ResNet and bidirectional LSTM network. The network structure and re-usability of the classification model were optimized experimentally，so the optimization model was obtained finally. The classification accuracy of the optimization model is 96.77%, and the running time after the model reuse optimization is 39.85 s. Compared with other machine learning algorithms, the proposed approach achieves good results in both classification accuracy and efficiency. The performance of the proposed model is better than that of traditional intrusion detection model.

Abstract:In order to solve the skyline query problem in partial order domain, this paper proposes an efficient query processing method for the skyline query in the partial order domain to meet people's increasing demand for query efficiency. Firstly, in order to improve the query efficiency of skyline on partially ordered domains, this paper introduces the inverted index into the skyline query and proposes an index structure based on the inverted index. Secondly, the basic algorithm PSP_B (Basic Partially-ordered Skyline Processing based on inverted index, PSP_B) is proposed. The PSP_B consists of two phases: in the first step, each partially ordered domain is converted into two fully ordered domains through mapping function, and then each fully ordered dimension is managed through the inverted index; in the second step, the scan end point is found through scanning the inverted index and the result set is obtained. Thirdly, based on the PSP_B, this paper further proposes an optimization algorithm PSP_I (Improved Partially-ordered Skyline Processing based on inverted index, PSP_I). The PSP_I can further improve the computational efficiency by grouping the data in advance and then indexing them. Finally, a large number of experiments prove the correctness and efficiency of the proposed algorithm.

Abstract:Aiming at the three-dimensional bin loading problem of cargo, a three-dimensional cargo loading model is established. In the model, in order to avoid the phenomenon of rolling over due to the eccentricity during the turn of the goods in the process of transportation, the gravity center constraint during the turn was added to obtain the projection of the gravity center area as an isosceles triangle or isosceles trapezoid. The cargo placement rules expand the remaining space area and increase the diversity of understanding. In order to improve the speed of iterative convergence and enhance its global optimization ability, an improved crow search algorithm is adopted to solve and optimize the model. In the improved algorithm, a multi-probability random walk strategy and a reconciliation strategy are proposed and introduced. The solution repair strategy makes the algorithm suitable for model solving and increases the diversity of solutions as much as possible. The multi-probability random walk strategy is to continue to walk randomly with different probabilities after population iteration, which makes the global optimization ability of the algorithm stronger. Simulation examples and benchmark function test results show that the improved algorithm has obvious optimization effect.

Abstract:In order to solve the problem that traditional methods cannot achieve a good balance between the accuracy and efficiency of SQL injection behavior detection in the real-time high-speed network traffic environment， this paper proposes a method for real-time detection method of SQL injection behavior based on deep learning construction model, and constructs a detection network model called SQLNN based on Convolutional Neural Networks (CNN) and introduces a fast Fourier transform layer. Based on this model, an online detection and adaptive training framework for SQL injection behavior is proposed. For our detection framework, the detection accuracy of the SQL injection statements reaches 99.98%, and it can detect about 10 000 packets containing SQL statements per second. Therefore, it can satisfy the requirements of real-time online detection of SQL injection attacks for detection accuracy and efficiency.

Abstract:In view of the influence of pedestrians on vehicle driving in traffic scenes and the problem that the assisted driving needs to avoid the danger for pedestrians, a pedestrian hazard assessment method based on vehicle-mounted monocular cameras is proposed. Based on the characteristic environment of Chinese cities, this paper divided the driving environment into three scenarios: regular roads, crosswalks, auxiliary roads. Different risk assessment methods are used for each type of scenarios. A convolutional neural network is used to detect and identify pedestrians, auxiliary police, signal lights and sidewalks on the road in the video. Then, it detects the key points of the pedestrian and uses the multi-target tracking method to generate the time series of the pedestrian skeleton. Pedestrian behavior and trend are obtained through LSTM（Long-Short Term Memory Neural Network) analysis of posture sequences. Finally, a pedestrian hazard assessment model is built to realize the pedestrian hazard assessment in multi road scene by synthesizing the video information, pedestrian information and scene information. The experimental results show that the scene classification makes the assessment results of the hazard model more consistent with the actual pedestrian hazard. The proposed model can effectively evaluate the pedestrian hazard and assist the drivers to drive safely.

Abstract:For the exterior design of virtual clay model in automotive industry, a novel variable stiffness brush model and haptic decorating method are proposed using a six DOF input device and based on real-time force feedback technology, and the haptic behavior of virtual 3D brush based on variable stiffness is studied in detail. Firstly, the relationship between brush deformation and endured force is examined by employing the bending spring-mass model to construct the 3D brush mechanical model. Then, the collision detection between virtual hairy brush and virtual 3D object is studied based on a collision algorithm of Weighted Average Distance. An effective ball expanding operation is used to compute the smallest bounding sphere of the bent brush and then to determine the projection plane. The 2D footprint produced between the brush and the projection plane is calculated according to the deformation of the brush at a sampling point, and then, the 3D brush footprint can be obtained by projecting the 2D brush footprint onto the 3D object surface. The 3D brush stroke is formed by controlling the exerted force and superimposing 3D brush footprints along the direction of painting. Experiment results show that the adopted method can effectively enhance the reality to users.

Abstract:In order to mitigate the impact of wind power fluctuation on the power grid, a model predictive control algorithm is proposed to analyze the optimal allocation of energy storage system with different fluctuation rate of wind power. Firstly, based on the model predictive control (MPC) algorithm, the control strategy of using energy storage to smooth the wind power fluctuation is studied, and an optimal configuration model is established. Secondly，the concepts of positive and negative fluctuation rate and cumulative fluctuation rate of wind power are proposed，and the power and capacity allocation strategies of energy storage system under three typical fluctuation rates are analyzed in steps. Finally, three typical scenarios, from the established standard sinusoidal wind power to the randomly selected wind power, are analyzed based on MATLAB software to verify the effectiveness of wind power fluctuation mitigation strategy based on model predictive control algorithm and the cumulative fluctuation rate difference as energy storage size evaluation index, which provides a reference for the friendly grid connection of renewable energy and energy storage optimal configuration.

Abstract:According to the debug requirements of L-DSP, an on-chip debug circuit based on JTAG interface is proposed in this paper, which implements the debug functions such as storage resource access, CPU pipeline control, hardware breakpoint/observation point, and parameter statistics. Compared with the traditional debug mode, the proposed debug circuit realizes the direct transmission of data between peripherals and memory by adding a DT-DMA module, which greatly improves the debug efficiency. The proposed circuit is designed in a 0.18 μm CMOS process with an area of 167 234.76 μm2 and a power consumption of 8.89 mW. And the proposed circuit and L-DSP are verified under the FPGA. The results show that the proposed circuit has complete debug functions and the rate of DT-DMA for transferring debug data is three times faster than that of the CPU.

Abstract:In order to make the model-free adaptive control（MFAC） better solve the control problem with noisy system, this paper examines the noise system and applies improved tracking differentiator in MFAC. Filtering is performed in the feedback process, and a MFAC method based on improved tracking differentiator（ITD） is proposed. The convergence of the algorithm is also proved. The simulation experiment proves that the improved control method can quickly track a given signal and has good resistance to noise interference. Finally, it is applied to the control of the drum water level of circulating fluidized bed （CFB） boiler.

Abstract:In order to reduce the complexity of multilevel voltage space vector modulation （SVPWM） in practical implementation，and improve the real-time performance of multilevel converter system，in this paper，by combining the advantages of phase shift pulse width modulation（PS-PWM） and carrier disposition PWM（PD-PWM），a novel multilevel SVPWM implementation based on carrier configuration is proposed，which can improve the utilization of the DC voltage，reduce the total harmonic distortion（THD） of the output and improve the time complexity of the algorithm，which means the novel algorithm can be easily applied to any level cascaded H bridge converters. In addition，the novel algorithm ensures the power balance between each unit，which keeps the advantage of the modular design. Finally，the effectiveness of the proposed modulation strategy is verified by simulation and experiment.

Abstract:The effects of trace rare earth element Gd on the microstructures and corrosion resistance of 7056 aluminum alloy were investigated by intergranular corrosion（IGC），stress corrosion crack（SCC） and electrochemical corrosion tests, combined with optical microscopy（OM），scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. The experimental results showed that the addition of 0.11% Gd to 7056 aluminum alloy forms L12-Al3（Gd，Zr） dispersion phase, which improved the recrystallization resistance of the alloy by strongly hindering the movement of dislocation and grain-boundary, and allowed the matrix to retain more fine subgrain structure. Compared with the large-angle grain boundary, the corrosion potential difference between the subgrain boundary and the crystal was smaller，and the corrosion driving force was reduced. Compared with 7056 aluminum alloy，7056-Gd aluminum alloy had greater resistance to stress corrosion crack. Its critical stress intensity factor is increased from 5.45 MPa·m1/2 to 10.59 MPa·m1/2. The results of open circuit potential（OCP），electrochemical impedance spectroscopy （EIS） and cyclic polarization curves of the two alloys are consistent, indicating that 7056-Gd aluminum alloy has higher corrosion resistance.

Abstract:As the destruction of the backfill caused by the mining of the ore body can be regarded as a loading process at different loading rates, a uniaxial compression test of cemented filling bodies under five loading rates was carried out in the laboratory. Based on the stress-strain curve of the filling body, according to the principle of energy dissipation and damage mechanics, the energy consumption value of the backfill at different loading rates was calcu lated and the corresponding damage evolution equation was constructed. Therefore, the internal relationship between the energy dissipation of cemented filling and the axial compression time and strain at different loading rates was studied, and the evolution process of energy damage for the cemented filling body under compression was discussed. The results show that unlike high-strength rocks, there is a critical loading rate for cemented backfill . When the loading rate exceeds the critical value, the backfill strength decreases with the increase of loading rate. The pre-peak energy consumption, post-peak energy consumption, strain energy per unit volume, and total energy consumption of the filling body have a quadratic function curve relationship with the loading rate. The total energy consumption of cemented backfill increases with the increase of axial compression time and axial strain in the form of a logistic function. However, the difference in loading rate makes the increase rate of energy consumption value, and the energy consumption of the backfill under the same axial deformation has obvious differences. The compression failure of backfill under different loading rates exhibits the same kind of damage process. The energy damage evolution process of the backfill under uniaxial loading can be divided into four stages: initial damage, stable development of damage, acceleration of damage and damage failure.

Abstract:The effects of quenching water temperature（20 ~ 80 ℃） on the microstructure and mechanical property of 2219 Al alloy forging ring were studied by room temperature tensile test, optical microscope（OM），scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. The results showed that the tensile strength and yield strength first increased and then decreased with the increase of quenching temperature. The elongation anisotropy index of 2219 Al alloy ring forging was significantly increased when the quenching water temperature exceeds 60 ℃ due to the formation of coarse grain boundary precipitates. The high strength and elongation of 2219 Al alloy ring forging was obtained under the quenching water temperature at 40 ℃. The axial tensile strength, yield strength and elongation were 418 MPa，300 MPa and 9.3%, respectively. The radial tensile strength，yield strength and elongation were 420 MPa，300 MPa and 9.8%, respectively. The tangential tensile strength，yield strength and elongation were 447 MPa，329 MPa and 12.6%，respectively.

Abstract:In this paper, different kinds of organic amines were used to modify ZIF-8 catalysts prepared via solvothermal method，and the effects of organic amine structural characteristics on the catalytic activity of ZIF-8 for Knoevenagel condensation reaction were discussed. The results show that ZIF-8 modified by organic amine still maintains the rhombohedral dodecahedron structure and possesses regular morphology，without obvious difference from that of unmodified materials. The BET specific surface areas of ZIF-8 modified by 1，2-propylenediamine，diethylenetriamine and triethylenetetramine are 1 893 m2·g-1，1 885 m2·g-1 and 1 861 m2·g-1，respectively, decreased by about 6.5% compared with that of the unmodified materials, mainly due to the blockage of pores for ZIF-8 by organic amines. When ethanol works as solvent, the amount of catalyst is 0.6 mol%（molar ratio to benzaldehyde），the reaction temperature is 80 ℃. When the reaction time keeps for 210 min，1，2-propanediamine modified ZIF-8 exhibits the highest catalyst activity，and the yield of ethyl α-cyanocinnamate reaches 97.8 %. After 10 cycles，the yield of this reaction is still up to 90 %，an increase of 35.3 % higher than that of unmodified ZIF-8. The studies on the catalytic mechanism of amine-modified ZIF-8 indicate that amines modified ZIF-8 can improve the amount of activity site，while 1，2-propanediamine has a shorter chain and less steric hindrance, making its N sites easier contact with reactants. It combines with the original imidazole N site on ZIF-8 to coordinate with α-H on the methylene of benzaldehyde through lone pair electrons, therefore significantly improving the catalytic activity of the catalyst clearly.

Abstract:To rationally design the best bifunctional water decomposition electrocatalyst with low cost and high activity is significant for achieving efficient conversion and storage of sustainable energy. An improved self-supporting stainless steel mesh electrocatalyst is obtained by the steps of corrosion, immersion and phosphating. The electrochemically modified stainless steel electrocatalyst exhibited excellent electrocatalytic performance for both hydrogen evolution reaction（HER） and oxygen evolution reaction（OER） in alkaline medium，displaying Tafel slope of 87.41 mV·dec-1 and 90.1 mV·dec-1，respectively. At current density of 10 mA·cm-2，the electrochemically modified stainless steel mesh electrocatalyst exhibited low overpotential of 164 mV and 240 mV，allowing it to be used as bifunctional electrocatalyst for overall water splitting with enhanced overall voltage of 1.66 V at10 mA·cm-2.