High penetration of Photovoltaic (PV) systems is variable resource as challenges to the stability and power quality of electrical grids. Accurate prediction of PV power has been recognized as a way to solve this problem. Due to PV power periodicity and non-stationary characteristics, traditional power prediction methods based on linear or time series models are no longer applicable. Methods based on neural networks are widely used for power prediction for PV system. Considering the training time and network accuracy, this paper discusses the factors in the prediction model. The number of nodes in the hidden layer that the network accuracy is high and the training time is guaranteed is determined, rather than just using the formula. After determining the number of nodes in the hidden layer, this paper presents a method combining artificial neural network (ANN) and wavelet decomposition (WD) for power prediction for PV system. Solar irradiance and other six parameters are chosen as the input of the hybrid model based on WD and ANN. The output of the neural network is reconstructed to obtain the final predicted power. The proposed model are validated by experimental data to predict the output power of PV system effectively and accurately, which is useful to enhance the safety and stability of the electrical grid.

To solve the problem in the large deformation of surrounding rock of highly nonlinear time sequence problem,the Gaussian process regression(GPR)theory is introduced,which can handle small samples and highly nonlinear problems.Two tunnels are selected as typical samples: Japan Nagasaki Ureshino Tunnel and Sichuan Wangdeng Tunnel,for the long-term monitoring data from the training sample,using GPR method to build the tun-nel surrounding rock large deformation forecast model.Main conclusions:①compared with the traditional forecas-ting models such as ANN,SVM,GM(1,1),GPR prediction model can be more accurate to predict tunnel vault subsidence value and the net convergence value;②on a large rock mass deformation inflection point of nonlinear phase,its forecast trend more accord with the engineering practice,can be more reasonable for large deformation of surrounding rock of the early stage of implementation, and then as soon as possible to realize the construction of early warning and support scheme comparison optimization;③GPR algorithm is verified by engineering examples, can be efficient and accurate to predict the deformation of surrounding rock of the tunnel,can provide reference for similar projects.

Image processing technology has been developed rapidly in recent years, and altering the content of an image is easy for everyone, but may be illegal for an attacker. Thus, it is urgent and necessary to overcome this problem to protect the integrity and authenticity of images. Watermarking is a powerful technique proposed to solve this problem. This paper introduces a robust image watermarking algorithm working in the wavelet domain, embedding the watermark information into the third level low frequency coefficients after the three-level discrete wavelet transform (DWT) and singular value decomposition (SVD). Additionally, to improve the robustness to geometric attacks, the affine-scale-invariant feature transform (ASIFT) is applied to obtain feature points which are invariant to geometric attacks. Then, features of acquired points between the watermarked image and the received image are used to realize the resynchronization to improve the robustness. Experimental results show that the proposed algorithm achieves great balance between robustness and imperceptibility, and is robust against geometric attacks, JPEG compression, noise addition, cropping, median filters, and so on.

A simplified approach for the nonlinear analysis of the load-displacement response of a single pile is presented using the load-transfer approach. In the present method, a hyperbolic model is adopted to simulate the load-displacement response of both the pile base and the shaft. Using the Mindlin displacement solution of the elastic half-space, the pile end settlement induced by the skin friction of pile is calculated. Based on the present analytical method, a highly effective iterative computer program is developed for the analysis of the response of a single pile. The validity of the present method is then demonstrated with the results of the load tests carried on instrumented piles. The calculated results indicate that at all loading levels, the proposed method is generally in good agreement with the well-documented field test results and the calculated results derived from other approaches. It is noted the pile head displacement obtained from the present approach increases with increasing failure ratio of skin friction and end resistance at the same loading level. It is also observed that the influence of the failure ratio of skin friction to the pile head displacement is slightly larger than the influence of the pile end resistance.

In order to control production blasting and optimize mining operation, it is important to study the step topography vibration amplification and attenuation effect in the open-pit mine. Surface particle vibration velocity attenuation characteristics, the formation, and change rules of the terrain effect were studied by analyzing the field measured data. Results show that local amplification effect and local attenuation amplification effect of particle vibration velocity are obvious. Amplification effect associates with bench height, and the attenuation effect is closely related with the distance from the vibration source and distance from the top. With the increase of elevation, vibration magnification of the particle on the top was 1.1∼1.4. Because of the influence of the terrain effect, particle vibration velocity on the slope toe was obviously inhibitory. Based on the measured data, elevation amplification factor and clamping effect factor which influence blasting vibration velocity are put forward, and a new mathematical model considering the attenuation coefficient, the elevation amplification coefficient, and the clamping effect coefficient for predicting the blasting vibration velocity of the step topography is further improved. The regression analysis results show that the fitting coefficient of determination of the new prediction model is 0.8152 in horizontal and 0.8902 in vertical, respectively, and the prediction error is less than 20%, which is much better than other formulas. This new model provides effective reference for blasting seismic wave propagation law research of slope engineering.

With the rapid development of computer technologies, a number of image modification methods have emerged, which have great impacts on the security of image information. Therefore, it is necessary to protect the integrity and authenticity of digital images, and digital watermarking technique consequently becomes a research hotspot. An effort is made to survey and analyze advancements of image watermarking algorithms based on singular value decomposition (SVD) in recent years. In the first part, an overview of watermarking techniques is presented and then mathematical theory of SVD is given. Besides, SVD watermarking model, features, and evaluation indexes are demonstrated. Various SVD-based watermarking algorithms, as well as hybrid watermarking algorithms based on SVD and other transforms for copyright protection, tamper detection, location, and recovery are reviewed in the last part.

Watermarking techniques can be applied in digital images to maintain the authenticity and integrity for copyright protection. In this paper, scale-invariant feature transform (SIFT) is combined with local digital watermarking and a digital watermarking algorithm based on SIFT, singular value decomposition (SVD), and all phase biorthogonal transform (APBT) is proposed. It describes the generation process of the SIFT algorithm in detail and obtains a series of scale-invariant feature points. A large amount of candidate feature points are selected to obtain the neighborhood which can be used to embed the watermark. For these selected feature points, block-based APBT is carried out on their neighborhoods. Moreover, a coefficients matrix of certain APBT coefficients is generated for SVD to embed the encrypted watermark. Experimental results demonstrate that the proposed watermarking algorithm has stronger robustness than some previous schemes. In addition, APBT-based digital watermarking algorithm has good imperceptibility and is more robust to different combinations of attacks, which can be applied for the purpose of copyright protection.

Currently, most digital image watermarking schemes are affected by geometric attacks like rotation, scaling, and translation (RST). In the watermark embedding process, a robust watermarking scheme is proposed against RST attacks. In this paper, three-level discrete wavelet transform (DWT) is applied to the original image. The three-level low frequency sub-band is decomposed by the singular value decomposition (SVD), and its singular values matrix is extracted for watermarking embedding. Before the watermarking extraction, the keypoints are selected by scale-invariant feature transform (SIFT) in the original image and attacked image. By matching the keypoints in two images, the RST attacks can be precisely corrected and the better performance can be obtained. The experimental results show that the proposed scheme achieves good performance of imperceptibility and robustness against common image processing and malicious attacks, especially geometric attacks.

Manufacturers of photovoltaic panels typically only provide electrical parameters under standard reference condition (SRC) that is not sufficient to determine their overall performance. It is important for designers to find a flexible and reliable method to model and accurately predict I-V characteristics under varying operating conditions. This paper proposes a method to predict the I-V characteristics of a PV panel under varying operating conditions by combining the single diode model and explicit analytical model. The method takes temperature and solar irradiance as inputs and produces I-V characteristics under any operating condition as outputs, including the maximum power point, fill-factor, and entire I-V curve. Considering the aging effect, the parameters under the measured reference condition (MRC) are used for calculation instead of the manufacturer data at SRC where the process is as follows: (1) the shape parameters in the explicit analytical model were calculated from measurements at MRC; (2) the physical parameters in the single diode model were identified from the measured data at MRC and used for the prediction; (3) the physical parameters under any operating condition were calculated based on the dependence of the physical parameters on the temperature and solar irradiance; (4) the I-V characteristics were described and analyzed using the explicit analytical model because of its simplicity and explicit expression. Outdoor experiments were performed to validate the proposed method. Our calculated results show reasonable agreement with the experimental results. (C) 2017 Elsevier Ltd. All rights reserved.

As "the cancer of the engineering", expansive soil is widely distributed in China. To systematically evaluate the risk grade of expansive soil cut slope stability during construction, based on research results of 22 expansive soil road sections constructed in Guangxi, Yunnan, Henan, Beijing of China, the risk surroundings, factors and feedback information of risk management are analyzed; and the hierarchy model is established consisting of two indexes layer with 8 main evaluation indices. Grading standard of evaluation indices are established by statistics and theoretical analysis; and the weights of evaluation indices are obtained by using analytic hierarchy process. The dynamic recognition model of expansive soil cut slope stability is eventually established by using fuzzy recognition theory and analytic hierarchy process (FAHP). The preliminary assessment of risk surroundings and secondary dynamic assessment of risk factors and feedback information of expansive soil cut slope of Nanyou road was carried out by using the established model; and then the calculated results are compared with field situation. The results indicate that the assessment results are basically in a good agreement with the observed results, so as to verify the rationality and practicability of the proposed model. The dynamic risk assessment methodology and model can provide a powerful tool for quantitative assessment of expansive soil cut slopes stability during the whole construction process.

In this paper,the tunnel collapse accident occurred in under building Wangdeng tunnel was taken as an exam-ple.Wangdeng tunnel was located in a meizoseismal area due to the 5·12 Wenchuan earthquake.The basic characteristics of tunnel collapse were analysed.Combined with the tunnel seismic prediction technology (TSP),the paper systematically introduced the collapse prediction,genetic mechanism and treatment measures for phyllite tunnel in meizoseismal area. Based on the long time monitoring data of surrounding rock deformation and pressure between surrounding rock and primary support,the tunnel collapse treatment scheme was checked to be highly efficient and rational.The engineering experience could be taken as a significant reference for other similar projects.

Elevation effect is an important content of the research on propagation law of blasting seismic wave. Based on the numerical simulation and theoretical analysis, the inducement and characteristics of elevation effect are revealed. The results indicate that vibration amplification effect is induced in a certain elevation. The amplification factor doesn’t increase monotonously. Amplification and attenuation effects on blasting vibration velocity exist simultaneously. According to the data analysis and theoretical analysis, a prediction model of vibration velocity on step topography is put forward.

A coupling analysis model is proposed to study the hydro-mechanical response of the fluid flow in fractured rock mass with the method of discontinuous deformation analysis (DDA). A model of fractured rock mass is generated with the DDA method. Based on this model, the fracture water network is also generated with the matrix search method. In the fluid flow analysis, the cubic law is applied to study the steady flow along the fractures using the steady-state equilibrium iteration method. Hydraulic pressure is treated as a line loading in the DDA framework, and the aperture and hydraulic pressure in the fracture line are updated every iteration step, followed by the coupled motion equations expressed in the DDA framework, to study the interaction between the fluid flow along the fractures and the movement of the rock blocks. A real case of cavern excavation is selected to study the influence of fluid flow with water tunnel during the excavation and operation phases with the proposed DDA coupled 2D hydro-mechanical model. The results show that the DDA coupled hydro-mechanical model is suitable for the stability and seepage analysis of practical engineering problems.

Based on joint statistics from the in-situ survey, using numerical simulation technique of joint network (Monte-Carlo method), the calculation model of fractured rock mass is generated. Underground seepage discharge filed in fractured rock mass surrounding storage caverns is analyzed by using distinct element method. The result of simulation has shown good agreement with surveying data. Two cases have been simulated that is water curtains is installed and is not installed. Water pressure distributions in joints are investigated in these two cases. It is shown that in the case without water curtain the groundwater in joints which locate the upper of underground caverns is drained out and water sealed conditions is completely unrealized. When water curtain pressure is set at 0.3MPa, can underground water seal the storage caverns.

The distribution of hydraulic pressure in fractured rock mass surrounding caverns after excavation and technique of stochastic generation of joint network are investigated based on discrete element method. In order to seal the oil in underground caverns with water in the actual engineering, a water curtain with water pressure is installed, and the changes of hydraulic pressure are simulated with a series of curtain pressures. It is shown that some joints that have been drained out during excavation can not be saturated if the water curtain pressure is less than a certain value. Water curtain pressure with a certain value gives a strong safe guarantee of saving oil in the underground petroleum storage caverns.

Function P-sets is a new mathematical model and structure, which is a new theory and method of studying the laws of dynamic information system. P-information law is the dynamic information law generated by function P-sets, which is information law pair composed of internal P-information and outer P-information law . Using the dynamic and law character-istics of P-information law, the study of attribute control and attribute control theorems of P-information are presented. Finally, the application of attribute control in image border information stabilization is given.

In studying axial hybrid magnetic bearing (HMB) for suspension in five degree of freedom (DOF), the relationship between radial electromagnetic force and magnetic bearing structural parameters and permanent magnet parameters should be calculated. In order to overcome the lack of analytical calculation model for radial electromagnet force of axial HMB, based on magnetic circuit analysis and calculation of magnetic conductance for each parts, the analytical calculation model for radial electromagnet force of axial HMB is proposed in this paper. The analytical formulation of radial electromagnetic force is derived by using virtual displacement method and demagnetization characteristics of the rare earth permanent magnet. It is found that the radial electromagnetic force increases with the radial displacement increasing approximately in linear relationship, and the radial force and stiffness decreases with the axial gap increasing. The radial electromagnetic force increased and then saturated with increasing permanent magnet effective length. The model of axial HMB is simulated by finite-element method software and the simulation results are basically in agreement with the calculated results.

Underground seepage discharge field in fractured rock mass surrounding storage caverns is analyzed by using discrete element method and stochastic joint-generation method. Meanwhile water pressure distributions in joints are investigated with a series of curtain pressures and compared with no water curtain. In the case without water curtain the groundwater in joints which locate the upper of underground caverns is drained out and water-seal conditions are completely unrealized. When the water curtain pressure is less than a certain value, the joints that have been drained out can not be saturated, and only the water curtain pressure exceeds this certain value, can groundwater seal the storage caverns.

Real time monitoring system of digitized agricultural water supply is a complex engineering. In this paper, the software and hardware design principal of real time monitoring and management system in water resources and the integrated characteristics of structure are introduced. The general planning of real time monitoring system in integrated system in agriculture water supply is proposed. This system, which is based on info technology and relies on computer technology, remote controlling and automatic technology, collects, transports and processes the water resource and its related info in the managed area in real time. The water resources are dispatched and distributed using scientific decisive mathematical model. The whole structure of the system can be divided into three parts: central management system, wireless communication net and enterprise subnet system. Some critical problems are discussed and demonstrated fully. This system has advanced performance and applicable prospect. The great social and economic benefit has been created by using real time monitoring system of agricultural water supply in the North area in Shandong province, China. By contrasting the year of 2005, the effect of conventional analysis is that the volume of scarcity of water in agricultural water supply system reaches 49.16 million m3. While the volume of scarcity of water is 35.48 million m3 by scientific management, so the volume of scarcity of water decreases 13.68 million m3. This means that we can save 13.68 million m3 water every year by optimizing the existing water resource. So it is necessary to dispatch the existing water resource scientifically on time and space, and the profit is great. The system has opened a new way for agriculture in China.

A series of Zn1-xCoxO,Ti1-xCoxO2,(In1-xCox)2O3 magnetic semiconductor films with high concentration of the transitional metal Co element(concentrated magnetic semiconductor) were prepared by sputtering machine.The super performance of the materials,such as the high Currie temperature above room temperature,high spin polarization ratio,and large magneto-optical Kerr effect were found in the concentrated magnetic semiconductor films.The electric transport properties were also systematically studied by experiments and theories,and a spin dependent variable range hopping model was proposed.The concentrated magnetic semiconductors are different from the conventional dilute magnetic semiconductors,and they may become good spin injection source and new transparent magneto-optical material.