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Fault detection in subsea pipelines is a difficult problem for several reasons, and one of the most important is the inaccessibility of the system. This criticality can be overcome by using transient test-based techniques. Such an approach is based on the execution of safe transients that result in small over pressures (i.e., on the order of a few meters of water column). In our companion paper, the procedure involving the transient tests was described in detail. This paper analyses the results of the field tests carried out and identifies wall deterioration in some sections of the pipeline. Attention is focused on the numerical procedure based on the joint use of a 1-D numerical model simulating transients in the pressurized flow and analytical relationships and providing the transient response of anomalies such as leaks and wall deterioration. The results obtained are essentially confirmed by the survey carried out by divers.

This study was conducted with the aim of developing a circuit system that enables the measurement of the moisture content and ion concentration with a simple circuit configuration. Our previous studies have shown that soil can be represented by an equivalent circuit of a parallel circuit of resistors and capacitors. We designed a circuit that can convert the voltage transient characteristics of the soil when a current is applied to it into a square wave and output frequency information and developed an algorithm to analyze the two types of square waves and calculate R and C. Normal operation was confirmed in the range of 10 kΩ–1 MΩ for the designed circuit, and the calculation algorithm matched within a maximum error of 5%, thus confirming the validity of the program. These successfully confirmed the changes in the water content and ionic concentration. The soil moisture content measurement succeeded in measuring a maximum error of about 10%, except at one point, and the soil ion concentration measurement succeeded in measuring a maximum error of 6.6%. A new, simple, noise-resistant moisture content and ion concentration measurement circuit system with square wave output has been realized.

To improve the transient response performance of digitally-controlled DC–DC switching converters, a fuzzy logic control proportional-integral–differential (FLC–PID) controller with both coefficient and error modifications is presented in this paper. The controller consists of a PID compensator and two fuzzy logic controllers (FLCers): one that adjusts the control coefficients of PID compensator and another that modifies voltage error input to it. These two FLCers have different fuzzy input subsets (FIS), leading to multiple modifications of control coefficients and voltage error for PID compensator. Consequently, the proposed controller results in finer FIS than a conventional FLC–PID controller without significantly increasing the hardware cost. Experimental results demonstrate that it yields a better transient performance in a DC–DC switching converter than does a conventional FLC–PID controller that only modifies the PID control coefficients: the transient performance can be improved by at least 50% and the required hardware resources can be reduced by at least 20%.

This study investigates the horizontal transient response of partially embedded pile groups in multilayered transversely isotropic soils. The dynamic equation of pile groups is derived using the FEM by considering pile–pile interaction. The flexibility matrix is presented by applying the fundamental transient solutions of multilayered transversely isotropic soils. Then, the interaction solution between the piles and soils is obtained by using a FEM–BEM coupled method. The correctness of the present solution is validated by comparing the results with those in existing literature. Numerical examples are given to explore how free-standing length, pile–soil stiffness ratio, pile spacing ratio, soil’s transverse isotropy and stratification affect the horizontal transient response of partially embedded pile groups.

Magneto-electro-elastic (MEE) materials are widely utilized across various fields due to their multi-field coupling effects. Consequently, investigating the coupling behavior of MEE composite materials is of significant importance. The traditional finite element method (FEM) remains one of the primary approaches for addressing such issues. However, the application of FEM typically necessitates the use of a fine finite element mesh to accurately capture the heterogeneous properties of the materials and meet the required computational precision, which inevitably leads to a reduction in computational efficiency. To enhance the computational accuracy and efficiency of the FEM for heterogeneous multi-field coupling problems, this study presents the coupling magneto-electro-elastic multiscale finite element method (CM-MsFEM) for heterogeneous MEE structures. Unlike the conventional multiscale FEM (MsFEM), the proposed algorithm simultaneously constructs displacement, electric, and magnetic potential multiscale basis functions to address the heterogeneity of the corresponding parameters. The macroscale formulation of CM-MsFEM was derived, and the macroscale/microscale responses of the problems were obtained through up/downscaling calculations. Evaluation using numerical examples analyzing the transient behavior of heterogeneous MEE structures demonstrated that the proposed method outperforms traditional FEM in terms of both accuracy and computational efficiency, making it an appropriate choice for numerically modeling the dynamics of heterogeneous MEE structures.

This work presents the nonlinear transient response of imperfect functionally graded material (FGM) folded plates having square and circular cutouts. The top and the bottom layers of the imperfect FGM folded plate is made of pure ceramic and pure metal, respectively and the effective elastic property at any point along the thickness is estimated according to the rule of mixture. First-order shear deformation theory in conjunction with eight-noded isoparametric element and five degrees of freedom per node along with von Karman type nonlinearity is used in the development of the finite element method (FEM) based formulation. A global type imperfection (G1) is modelled using an imperfection function. The governing differential equation is obtained using total Lagrangian formulation. Further, the Newmark average acceleration method in conjunction with modified Newton–Raphson is used to obtain the nonlinear transient response of the functionally graded material folded plate. The results obtained from the present finite element formulation are first compared for a wide range of parameters to establish the correctness of the present finite element formulation. The parametric study is carried out to investigate the effect of cutout size, cutout shape, amplitude of geometric imperfection, crank angle and boundary condition on the nonlinear transient response of an imperfect functionally graded material folded plate having cutout.

Based on an 0.18 μm process, this paper proposes a fully integrated 1.8 V output 300 mA load low-dropout linear regulator (LDO) with a fast transient response. By inserting a transient-enhanced biased Class AB super source follower at the gate of the output power transistor, this LDO can quickly adjust the gate voltage of the power transistor without additional power consumption. By adding an active capacitor circuit composed of a fast comparator with offset voltage at the output point, this LDO can quickly charge/discharge the transient current and accelerate the transient response without reducing the circuit stability. Simulation results show that the proposed LDO has an output voltage of 1.8 V, when the input voltage is 2 V to 5 V while consuming 66.4 μA of quiescent current. The proposed capless LDO has a 1.94 µV/mA load regulation, a 0.55 mV/V linear regulation, and a −60 dB@1 kHz power supply rejection. When the load current steps from 3 mA to 300 mA in 300 ns, the LDO settles in 400 ns with an overshoot and undershoot of 67 mV and 86 mV, respectively.

Introduction Based on the modified couple stress theory and the hyperbolic tangential mixed shear deformation theory, the free vibration and the transient responses of the functionally graded piezoelectric (FGP) sandwich microplates with considering the thermal–electric effects are investigated. Methods By introducing the porosity volume fraction, the perfect FGP sandwich mocroplate are destroyed and porous FGP sandwich plates are constructed. Electro-elastic material properties of porous FGP microplate vary across the thickness based on the modified power-law model. The governing equations derived from Hamilton's principle are solved analytically. Results By comparisons with the FEM simulation results and the previous results in the literature, the accuracy of the present established models is confirmed. Then the influences of thermal loadings, porosity volune fraction, material gradation, length scale to thickness ratios and facesheet thickness on the dynamic behaviors of FGP sandwich microplates are discussed. Significance These research can provide a theoretical basis for the accurate design of smart structures made of functionally graded piezoelectric materials.

Image thresholding is one of the fastest and most effective methods of detecting objects in infrared images. This paper proposes an infrared image thresholding method based on the functional approximation of the histogram. The one-dimensional histogram of the image is approximated to the transient response of a first-order linear circuit. The threshold value for the image segmentation is formulated using combinational analogues of standard operators and principles from the concept of the transient behavior of the first-order linear circuit. The proposed method is tested on infrared images gathered from the standard databases and the experimental results are compared with the existing state-of-the-art infrared image thresholding methods. We realized through the experimental results that our method is well suited to perform infrared image thresholding.

This paper presents a fast transient response low-dropout (LDO) regulator with all-NPN push–pull buffer in 0.6-μm bipolar process. In order to improve the transient response, an all-NPN push–pull buffer is proposed. Based on single Miller capacitance (SMC), the use of the all-NPN push–pull buffer overcomes the shortcomings of the equivalent series resistance (ESR) that requires strict output capacitor types. Besides, the proposed merging structure of bandgap reference and error amplifier not only improves the transient response, but also simplifies the circuit and reduces the output noise. Implemented and fabricated in a 0.6-μm bipolar process, the proposed LDO regulator occupies an active area of 1.6 mm 2 . The measured maximum load current is 200 mA, and the circuit can work at the load current of 300 mA. Moreover, the measured line regulation and load regulation are 0.8 mV/V and 0.09 mV/mA, respectively.