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profiled side channel analysis is considered as the most powerful side channel analysis by obtaining a copy of the attacking targe. With the population of deep learning technology in side channel analysis, Benadjila. R et al. proposed a profiled side attacks strategy based on convolutional neural network for AES with first-order mask countermeasure. However, this paper only implements training analysis while keeping the number of convolutional layers in the convolution module consistent and without trying to use common convolution kernel sizes. This paper conducts parameter selection experiments on the number of convolutional layers under the convolution module in the convolutional neural network and the size of the commonly used convolution kernel, and proposes a new optimized network model.As a result, this model can find out the correct key within 54 traces, which is better than the 180 traces record of Benadjila. R et al.

Earth pressure is the most important type of load acting on the supporting structure of a foundation pit, and it is also a key factor in the design of foundation pit supporting. However, in engineering practice, the calculated value differs greatly from the actual value, which puzzles many engineers. This paper analyzes the field measured data of the earth pressure of the foundation pit in Minghucheng (Jinan city), and compares the calculated values of the Rankine active earth pressure and the passive earth pressure theory. The analysis finds that: (1) The measured value is between the active earth pressure and the passive earth pressure, and as the excavation of the foundation pit and the inward displacement of the supporting structure, the measured earth pressure value becomes smaller and approaches the active earth pressure. (2) When the pre-stressed anchors is applied, due to the fastening effect of the anchors, the earth pressure behind the supporting pile has a tendency to increase. (3) The theoretical value of Rankine’s active earth pressure in the soil-rock combination is obviously lower than the measured values.

In this study, the monocrystalline silicon (c-Si) solar cell irradiated by 100 KeV proton beams at various fluences is investigated. A one-dimensional two-layer carrier density wave model has been developed to estimate the minority carrier lifetime of n-region and p-region of the non-irradiated c-Si solar cell by best fitting with the experimental photocarrier radiometry (PCR) signal (the amplitude and the phase). Furthermore, the lifetime is used to determine the initial defect density of the quasi-neutral region (QNR) of the solar cell to predict its I–V characteristics. The theoretically predicted short-circuit current density (Jsc), and open-circuit voltage (Voc) of the non-irradiated samples are in good agreement with experiment. Then a three-region defect distribution model for the c-Si solar cell irradiated by proton beams is carried out to describe the defect density distribution according to Monte Carlo simulation results and the initial defect density of the non-irradiated sample. Finally, we find that the electrical measurements of Jsc and Voc of the solar cells irradiated at different fluences using 100 KeV proton beams are consistent with the PCR predicting results.

An inverse analysis methodology is developed to simultaneously identify the thermal diffusivities and subsurface defect of carbon fiber reinforced polymer (CFRP) laminate through lock-in thermographic phase (LITP) profile reconstruction. A hybrid algorithm that combines simulation annealing algorithm (SA) and Nelder–Mead simplex search method (NM) is proposed to minimize the objective function constructed by LITP profile for determination of the thermal diffusivities ( α x and α z ) and subsurface defect characteristics (size D and depth H D ). For the hybrid method, SA is used to find a better feasible initial-guessed solution for NM. Numerical examples show that LITP has the merit of identifying the thermal diffusivities of CFRP laminate by inverse analysis. In comparison with SA and NM, respectively, the hybrid method can be converged to yield good estimates faster and more efficiently. Experimental and simulation LITP of defective regions are used to determine the thermal diffusivities and the size and depth of subsurface defect. The results show that the estimated thermal diffusivities and the size and depth of defect are in good agreement with the reference values, and the relative deviations are less than 5%. Nevertheless, this approach can only be applied for the determination of thermal diffusivities of CFRP laminate with subsurface defect.

Edge detection is an important technology in image segmentation, feature extraction and other digital image processing areas. Boundary contains a wealth of information in the image, so to extract defects’ edges in infrared images effectively enables the identification of defects’ geometric features. This paper analyzed the detection effect of classic edge detection operators, and proposed fuzzy C-means (FCM) clustering-Canny operator algorithm to achieve defects’ edges in the infrared images. Results show that the proposed algorithm has better effect than the classic edge detection operators, which can identify the defects’ geometric feature much more completely and clearly. The defects’ diameters have been calculated based on the image edge detection results.

An investigation on SiC coated carbon–carbon (C/C) composite plates has been undertaken by pulsed thermography. The heat transfer model has been built and the finite element method (FEM) is applied to solve the thermal model. The simulation results show that defects with DA/DP smaller than one can hardly be detected by an infrared camera with the sensitivity of 0.02 °C. Certificated experiments were performed on the built pulsed thermography system. The thermal wave signals have been processed by subtracting background image method (SBIM), pulsed phase thermography (PPT), and temperature–time logarithm fitting method (TtLFM). The limit DA/DP of defects in SiC coated C/C composite plates with the thickness of 6 mm that can be detected by pulsed thermography with the presented signal analysis algorithms has been obtained.

This paper describes the quantitative analysis of the boundary, location and depth of subsurface defects by lock-in thermography. The phase difference between defective areas and non-defective areas illustrates the qualitative analysis of the boundary and the location of the subsurface defect. In order to accurately estimate the size, location and depth of the defects, the phase is normalised, the heat transfer partial differential equation (PDE) model is used to filter the noise of normalised phase image and the differential normalised phase profile is employed to determine the boundary and location of the defect. The profile of the differential normalised phase distribution has maximum, minimum and zero points that help to quantitatively determine the boundary and location of the subsurface defect. An artificial neural network (ANN) is proposed to determine the depth of the subsurface defect. Experimental results for a steel plate, a carbon fibre-reinforced polymer (CFRP) sheet–foam sandwich, and honeycomb structure composites with artificial subsurface defects show good agreement with the actual values.

A novel non-destructive ultrasound infrared lock-in thermography (ULT) testing method was presented in order to detect metal specimens with subsurface contacting interfacial defects. An experimental platform was built. Experiments had been carried out to Q235 plates with different testing parameters. The testing effect of amplitude and phase images was analyzed, and the relation between amplitude difference, phase difference, signal-to-noise ratio and modulation frequency was discussed. An adaptive neuro-fuzzy inference system model was built to forecast the depth of defects.

By investigating the influence of the difference of refractive index between core and cladding (nco-ncl), normalized frequency (V ) and core radius (?) on both the intramodal and intermodal nonlinear coefficients (NCs) respectively, we design a novel weakly-coupled four-mode fiber with low nonlinearity. In general, under the premise of ensuring the low NCs between two non-degenerate modes, this design can reduce the intermodal NCs (< 0.5 W-1 \cdot km-1) between two degenerate modes and optimizes the parameters of differential group delays (DGDs) and chromatic dispersion. The optimized few mode fiber (FMF) is eligible for transmission and mode de-multiplexing in the receiver.

This paper systematically presents the information about a sustainable city and the process of putting forward, developing and evolving the concept, and it provides an analysis of some current main views in the studies of sustainable cities. In this paper, it is argued that the construction of a sustainable city should not be carried out simply by bringing the concept of sustainable development down to the city level; sustainable development should be more materialized, scenario focused, and localized at the city level, and it should be internalized into the various dimensions of the construction of a city at the special temporal and spatial scales of a city. Based on literature reviews, this paper holds that there are three drawbacks in the current understanding of a sustainable city, mainly including: First, emphasis is placed on the internal equilibrium of a city, but no attention is paid to the negative environmental externalities of other cities or areas and the compensation for them; second, the ultimate goal of sustainable development — achieving equilibrium — is excessively stressed, while the embodiment of the stages of development and regional differences in the goal of sustainable development is overlooked; third, the form of the city is a key indicator for building a sustainable city, but this indicator is basically unavailable in the current definitions of sustainable cities. The definition and theory of a sustainable city should fully reflect the temporal and spatial nodes of differentiation in a sustainable city and the dynamic relationship of equilibrium between the systems of a city and the surrounding areas; its definition and theory should also realistically address the urban needs and the practice of the sustainable development of a city. Based on a comprehensive analysis, this paper stresses that a sustainable city is a city in which the form of the city is scientifically designed in line with a certain social and economic development level, and environmental conditions in order to optimize the internal and external functions, improve the system of urban governance, achieve a dynamic equilibrium among economic development, environmental safety, resource utilization and social equity, continuously enhance its capability for coping with risks, make it more livable, and provide positive externalities in perspectives of economy, environment and social governance for other cities.

In this letter, a nonlinear photothermal characteristic of dental tissues has been verified by photothermal radiometry at a given frequency with changing of the laser intensity. Subsequently, the high-frequency heterodyne lock-in thermography (HeLIT) scheme has been introduced to overcome shortages of the low infrared camera frame rate and the poor signal-noise ratio. The smooth surface tooth was artificially demineralized at a different time, and then it was detected by HeLIT, Results illustrated that the phase delay increases with the extension of the demineralized treatment time. The comparison experiments between HeLIT and the homodyne lock-in thermography for detecting artificial caries were carried out. Experimental results illustrated that the HeLIT has the merits of high sensitivity and specificity in detecting early caries.

Inspection of aerospace components has always been a challenge. Lock-in thermography is an active technique which is popularly being used for the nondestructive evaluation of subsurface defects in composite materials such as carbon-fiber-reinforced-polymer (CFRP) in aircraft structures. CFRP-foam layered structure composite is often used for anti-heat and adiabatic material in aerospace components. In this paper, a finite element analysis (FEA) of 3D heat conduction is developed in order to investigate the behavior of thermal waves in the CFRP-foam layered structure plates with finite thickness under convective and radiate conditions. The FEA simulation is then utilized to predict the magnitude and phase differences produced by CFRP face-sheet subsurface defects to obtain the optimum inspection parameters. The simulation results are compared with the experimental data. The use of optimum inspection parameters of lock-in thermography to detect PVC modeling defects of CFRP-foam layered structure is also presented in this paper.

A space monocrystalline silicon (c-Si) solar cell under low-energy (< 1 MeV) electron irradiation was investigated using noncontact photocarrier radiometry (PCR). Monte Carlo simulation (MCS) was employed to characterize the effect of different energy electron irradiation on the c-Si solar cell. The carrier transport parameters (carrier lifetime, diffusion coefficient, and surface recombination velocities) were obtained by best fitting the experimental results with a theoretical one-dimensional two-layer PCR model. The results showed that the increase of the irradiation electron energy caused a large reduction of the carrier lifetime and diffusion length. Furthermore, the rear surface recombination velocity of the Si:p base of the solar cell at the irradiation electron energy of 1 MeV was dramatically enhanced due to 1 MeV electron passing through the whole cell. Short-circuit current (Isc) degradation evaluated by PCR was in good agreement with that obtained by electrical measurement.

In this paper, the modulated laser-induced excess minority carrier density wave (CDW) of bipolar semiconductor is developed. An analytical expression of CDW in frequency domain is introduced. The numerical simulations are carried out to analyze the effects of minority carrier transport parameters (minority carrier lifetime, diffusion coefficient, and two surfaces recombination velocities) on response of laser-induced photocarrier radiometry (PCR) signal to frequency for semiconductor silicon wafer. The PCR amplitude increases with increasing the minority carrier lifetime, and decreased with increasing the carrier diffusion coefficient and surface recombination velocity. In contrast, the PCR phase lag decreases with increasing the minority carrier lifetime, and increases with increasing the carrier diffusion coefficient and surface recombination velocity. The silicon (Si) wafer with an artificial defect (mechanical scratch) on the surface is experimentally investigated by PCR scanning image system. The distribution maps of the minority carrier transport parameters are obtained by best-fitting method which is based on the carrier density wave analytical expression, and the influences of the artificial defect on carrier transport parameters are discussed in detail. The experimental results indicate that the surface recombination velocity and carrier diffusivity at artificial damaged location are dramatically increased compared with those in the healthy region. The carrier bulk lifetime of whole Si wafer is obtained to be about 38.33 μs by PCR scanning image measurements. Simultaneously, quasi steady-state photoconductance (QSSPC) method is used to measure the carrier effective lifetime of Si wafer, and it is about 33.85 μs. Therefore, the carrier bulk lifetime of Si wafer by PCR scanning image measurement is in good agreement with the QSSPC measurement. However, QSSPC measurement could obtain only the carrier effective lifetime of Si wafer. Furthermore, PCR scanning image measurement can be employed to measure the carrier transport parameters with high resolution in comparison with QSSPC measurement, and to evaluate the localized imperfection.

An analytic mathematical model of modulated laser-induced minority carrier density wave of silicon solar cells is developed, and light-induced carrier recombination radiation luminescence method (photocarrier radiometry (PCR)) is employed to detect the doping concentration, impedance and carrier transport parameters. The double knee characteristics of frequency domain response curve are investigated, and in a small ac signal case, the equivalent circuit topology structure of a solar cell is constructed. Through simulation analysis based on minority carrier density wave mathematical model, the effects of doping concentration, resistance and carrier transport parameters on the PCR frequency domain response are investigated. Donor/acceptor concentration, shunt resistance and carrier transport parameters of Si solar cell are obtained by PCR frequency-scanning experiments and multi-parameter fitting. The results show that the first knee position of PCR-detected large-area solar-cell frequency domain response curve is determined by the capacitive effect. The simplified mathematical model can be used to quantitatively describe and determine the doping concentration, shunt resistance and carrier transport parameters of silicon solar cell.