Experimental Simulation Analysis Research Articles

A robust image encryption algorithm based on Chua's circuit and compressive sensing

In terms of Chua's circuit system, compressive sensing (CS) and Haar wavelet, a novel image compression-encryption scheme (CES) is proposed in this paper. Firstly, the plaintext image is decomposed into approximate component and detail components through Haar wavelet. Then the approximate component is diffused by the threshold processing of local binary patterns (LBP) operator-based chaotic sequence which is produced by the combination of Chua's circuit and Logistic map. Next, the Lissajous map is applied to generate the chaos-combined asymptotic deterministic random measurement matrices (CADRMM) which are employed to measure the detail components in different compression ratios. In addition, the combination of mapped approximate and detail components is shuffled by the Logistic map. The experimental results and simulation analysis prove that the proposed cryptosystem is capable of reducing data for transmission and has good security performance under various attacks, especially for the shear and noise attacks.

Molten salt assistant synthesis of three-dimensional cobalt doped graphitic carbon nitride for photocatalytic N2 fixation: Experiment and DFT simulation analysis

In this work, three-dimensional cobalt doped graphitic carbon nitride was synthesized by molten salt assistant method. XRD, N2 adsorption, SEM, XPS, UV–Vis spectroscopy, N2-TPD and Photoluminescence were used to characterize the prepared catalysts. The result shows that the addition of molten salt remarkably changes the morphology of as-prepared catalyst. Cobalt exists as coordinative Co-N bond, which can chemisorb and activate N2 molecules, and promote the electron transfer from catalyst to the nitrogen molecules. The as-prepared cobalt doped g-C3N4 displays the NH4+ production rate of 5.8 mg·L−1·h−1·gcat−1, which is 24 times of bulk g-C3N4. Density functional theory (DFT) simulations show that cobalt doping can not only prolong NN bond which activate N2 molecules, but promote the electrons-holes separation efficiency of g-C3N4. The d orbit of cobalt easily acts as a channel for transferring electrons from the transition metal to the N2 molecule, which enhances the N2 photofixation ability.

Influence of spacer insulator material temperature characteristics on its electric properties

Spacer insulators are important insulating component of gas insulated switchgear(GIS). In order to analyze the influence of spacer insulator materials temperature characteristics on the electric performance, we tested the temperature distribution under work condition and the temperature characteristics of the material's relative permittivity. Then established a spacer insulator simulation model in finite element numerical simulation software to calculate its temperature and electric field. Using the temperature test results as a reference to verify the temperature calculation, and in order to analyze changes of the electric field along the surface of the spacer insulator, the temperature characteristics of relative permittivity have to be considered. Through the experimental research and simulation analysis, we found that the temperature characteristics of the spacer insulator materials have great impacts on the spacer insulator performance. When the temperature increases, the material relative permittivity also increases. In the low-temperature region of spacer insulator, the electric field intensity along the surface increases, so the electrical performance deteriorates. The conclusion of this paper can provide an important reference for further research about spacer insulator's working performance analysis.

Nutrients management and planting time adaptation to climate change for wet season rice production in subtropical India

The projected adverse impact of climate change on food grain production of tropical and subtropical latitudes necessitates the development of suitable agro-adaptations. We used open top chamber (OTC) experimental facility and simulation analysis to study the effect of elevated [CO2] with varying nutrients management on rice grain yield and to evaluate planting time adjustment as adaptation to climate change. The OTC experiments with ambient [CO2] level ([CO2] ~390 ppm) and elevated [CO2] (25% higher than the ambient) using cultivar ‘Swarna sub1 (140–145 days)’ were conducted during wet season of the years 2011 and 2012 at West Medinipur, India. Using CERES model, we simulated rice grain yield for future climate scenario (A1B) during the years 2020 (2010–2039) and 2080 (2071–2099) at four selected locations of the subtropical India. The elevated [CO2] in OTC increased panicle number, but decreased filled grain number per panicle, 1000-grain weight and grain yield. The increasing [CO2] had smaller adverse impact for integrated nutrients management as compared with chemical fertiliser. The model simulated grain yield reduction of 6.1−13.0% during 2020 and 14.4 −25.0% during 2080 with rising temperature 1.6 and 4.6°C, respectively, compared with the base period (1961–1990). Early planting during 25 June to 25 July received closure favourable temperature and rainfall during the crop growing period, hence had better adaptation to the climate change. Increasing dose of integrated nutrients and early planting is expected to minimise the adverse impact of climate change on rice production of the subtropical India.

Application research of image recognition technology based on CNN in image location of environmental monitoring UAV

UAV remote sensing has been widely used in emergency rescue, disaster relief, environmental monitoring, urban planning, and so on. Image recognition and image location in environmental monitoring has become an academic hotspot in the field of computer vision. Convolution neural network model is the most commonly used image processing model. Compared with the traditional artificial neural network model, convolution neural network has more hidden layers. Its unique convolution and pooling operations have higher efficiency in image processing. It has incomparable advantages in image recognition and location and other forms of two-dimensional graphics tasks. As a new deformation of convolution neural network, residual neural network aims to make convolution layer learn a kind of residual instead of a direct learning goal. After analyzing the characteristics of CNN model for image feature representation and residual network, a residual network model is built. The UAV remote sensing system is selected as the platform to acquire image data, and the problem of image recognition based on residual neural network is studied, which is verified by experiment simulation and precision analysis. Finally, the problems and experiences in the process of learning and designing are discussed, and the future improvements in the field of image target location and recognition are prospected.

Density correlation in liquid surfaces: Bedeaux-Weeks high order terms and non capillary wave background

We present Molecular Dynamics (MD) simulations of liquid-vapor surfaces, and their Intrinsic Sampling Method analysis, to get a quantitative test for the theoretical prediction of the capillary wave (CW) effects on density correlation done by Bedeaux and Weeks (BW) in 1985. The results are contrasted with Wertheim's proposal which is the first term in BW series and are complemented with a (formally defined and computational accessible) proposal for the background of non-CW fluctuations. Our conclusion is that BW theory is both accurate and needed since it may differ significantly from Wertheim's proposal. We discuss the implications for the analysis of experimental X-ray surface diffraction data and MD simulations.

Experimental and numerical simulation analysis on creep crack growth behavior of CLAM steel

The experiment and numerical simulation were performed to analyze the creep crack growth behavior of China Low Activation Martensitic (CLAM) steel under temperatures ranging from 500 °C to 600 °C with a step of 50 °C. The creep crack growth micro-mechanism under multiaxial state of stress was investigated with the compact tension (CT) specimens. The creep crack growth rates were simulated based on the Nikbin-Smith-Webster (NSW) model. The difference of the crack propagation behavior is correlated with the evolution of two types of precipitates: Cr-rich M23C6 and W-rich M6C phases. The coarsening of M23C6 carbides and the precipitation of M6C phase particles lead to dissolving of the solid solution elements and deteriorating the creep properties during the testing processes.

Mechanical property and damage evolution of concrete interface of ballastless track in high-speed railway: Experiment and simulation

The interface damage of ballastless tracks in high-speed railway is considered as one of the most critical damage problems, however, the mechanical property and damage evolution of the concrete interface of ballastless tracks are rarely ascertained, and maintenance of the interface damage has been a heavy burden on the modern railway networks. This work aims to reveal the damage constitutive relationship and fatigue performance of the concrete interface of double-clock ballastless track based on experimental tests and simulation analysis. Firstly, by making the composite specimen composed of half track-slab concrete and half supporting-layer concrete and by designing experiment programs for the interface cracking test, the full-field evolution of strain distribution of the specimen under monotonic splitting loading is obtained based on the digital image correlation (DIC) technique, and the key parameters of a cohesive zone model for describing the interface stress-displacement relationship is determined. Subsequently, the interface damage evolution is investigated by applying cyclic splitting loads, and the interface fatigue S-N curve is acquired and validated by comparing with relevant references. It is found that the fatigue life of the concrete interface can be easily predicted with only knowing its secondary growth rate of the opening displacement amplitude. Furthermore, to elucidate the practical application of the experiment data and proposed models, the interface damage evolution of the double-block ballastless track under monotonic and cyclic temperature gradient loads are investigated, respectively. Simulation results show that much attentions should be paid to the negative temperature gradient load (below −60 °C/m) that could cause initiation of interface cracks. The proposed fatigue S-N curve enable a convenient and effective prediction for the interface fatigue damage of ballastless track with different service state under random loading cycles.

Technical engineering design, thermal experimental and economic simulation analysis of absorption cooling/heating systems in China

In low temperature heat sources driven cooling/heating absorption systems, there are many equipment combinations. Usually, there are contradictions between the equipment efficiency and their economy; for example, the high efficiency- solar collector usually has a high price. So, in this paper, ten absorption cooling/heating systems with different heat sources and different absorption technologies are investigated for technical-economic-thermal analysis. The heat sources are flat plate solar collector, evacuated U-pipe solar collector and middle-temperature high efficiency solar collector and waste heat. The absorption chillers are 1-effect LiBr absorption chiller, 2-effect LiBr absorption chiller, novel 1–2 effect LiBr absorption chiller and novel high efficiency-heat-recovery ammonia water absorption system. The results show that 2-effect absorption chiller with heat source of waste heat is the most optimized choice, which lowest payback period is about 1.9 years. The second choices are the 2-effect LiBr absorption system with novel middle-temperature solar collectors/natural gases and the novel ammonia water absorption system with waste heat sources.

Tests and Analysis of a Small-Scale Hybrid-Type DC SFCL Prototype

In recent years, high-voltage dc power transmission is widely developed in the world. However, it is difficult for the existing dc breaker to cut off the fault transmission line with large short-circuit fault current. In a short-circuit fault of dc systems, short-circuit fault current is composed of initial transient impulse current and steady-state fault current. Therefore, a hybrid-type dc superconducting fault current limiter (SFCL) is proposed with two-stage current limiting capability. In the early stage of short-circuit fault, initial transient impulse current is limited by inductance and resistance. In the later stage of short-circuit fault, a sustained and steady current-limiting resistance is provided by the dc SFCL. A small-scale prototype of the dc SFCL is developed and the parameter design of the dc SFCL prototype is presented. According to the experimental tests and simulation analysis, the design scheme's effectiveness can be confirmed from high current-limiting ratio. Based on experimental tests and simulation analysis, the current-limiting characteristics and energy loss characteristics of the hybrid-type dc SFCL have been well verified.

Evaluation and modeling scouring and sedimentation around downstream of large dams

Flip buckets are often used at the end of chute spillways to dissipate energy and direct flow to submergence plunge pool and especially in large dams. Flip buckets with central deviation also are a specific and new design of these buckets that have a transverse slope and are mixed in plan with a curvature. In this paper, the experimental and numerical simulation study of sediment scouring in such flip bucket has been targeted. Extensive experimental data are obtained from physical model studies conducted at Water Research Institute, Iran. The flow field with various flood discharges in a range of Froude numbers (Fr = $$V/\sqrt {gh}$$ : 3.5–7.5) in Flow3D model was compared to experimental results obtained from a similar model. Analyzing the simulated models in the Flow3D model and comparing the results with the experimental model, the hydraulic parameters of the pressure, velocity and depth of flow are determined. Considering the accuracy of the numerical model in simulating bed scouring, this model can be used for similar cases in large dams. The results of the simulation model compare well with the experimental results in parameters of the maximum scour depth, profile scouring and the ridge height which accumulates around downstream of the scour hole. This investigation improves the understanding of bed topography effects of downstream dams in high-velocity jet impact based on experimental observations and simulation analysis.

Experimental and numerical simulation analysis of R-290 air conditioner leak

Different mass R-290 (propane) leaked into the room from the inside and outside of a split type air conditioner indoor unit, and the refrigerant concentration was measured by infrared gas sensors. A CFD mode for RAC indoor unit including heat exchanger and fan was developed and verified by the test data. Through experiment and simulation, the dispersion characteristics of the refrigerant under different conditions were studied. The influence of installation height, leak point location, airflow rate and angle were tested and analyzed. Using velocity and concentration contours, jet camber resulted from leaked refrigerant and Coanda flow were illustrated clearly. The airflow volume at speed greater than 0.2 m/s could be applied directly to assess the effect of airflow on refrigerant mixing and diffusion.

Implicit authentication protocol and self-healing key management for WBANs

In recent years, the rapid development of computer science and technology brings health care into the information era. As a typical representation, wireless body area networks (WBANs) has also promoted the development of medical technology into a higher field. However, collecting data from users seriously affects personal privacy and security, that WBANs needs to overcome. In order to resolve the flaws of the existing secure authentication protocols in WBANs, we propose a lightweight implicit authentication protocol based on the Elliptic Curve Qu-Vantone (ECQV) algorithm. Moreover, we take advantage of the bidirectional key chain to design a group key management protocol between the personal digital assistance (PDA) and each of cluster head sensor nodes. The security and performance analysis show that our protocol can be performed with perfect forward security and backward security in data communication. In addition, the experimental simulation and theoretic analysis show that our protocol is more suitable for WBANs.

Revealing the essence of luminescence energy transformation from silica surfaces

Up to now, the underlying mechanism of the energy dissipation process of mechanoluminescence (ML) is still dubious. It is challengeable and significant to take the initiative to control in terms of light intensity and colour. Here, by rubbing silica surface against other materials, we are able to detect a controllable luminous energy emission, the colour as well as the intensity of which can be dominated by the crystal structural state of silica. The results show that Purplish blue light is observed between quartz and alumina, while the light emitted from the interfaces of amorphous silica and alumina is orange red which is also affected by external force. The basics of such phenomenon are well explained by both experimental and theoretical simulation analysis. Our results show that the emitted light colour transition from purplish blue to orange red, is suggested to be strongly related to the increase of defect centers in amorphous silica resulting from the structural changes in the rubbing surface. Our work provides a promising way for controlling mechanoluminescence, as well as a deep view into the basic mechanism of ML light emission.

Experimental and FEM Simulation Analysis of Lateral Extrusion Process on Bimetal Cross Fitting

The purpose of this paper is to study combines the finite element method model and experimental on bimetal cross fitting by lateral extrusion process. Fabricating bimetallic cross fitting by lateral extrusion technique remains some difficulties like taking the product out of the die hardly, harming the die longevity since the high compressive force and friction effects. The Finite Element Method (FEM) results of bimetal cross fitting lateral extrusion process were obtained from ABAQUS software such as: Stress distribution, metal flow and influence of sleeve thickness. Numerical results were compared with the experimental results shown a good agreement. The bimetal cross fitting has been successfully fabricated by lateral extrusion process. The results showed a close agreement between the numerical simulation and experimental analysis of bimetal cross fitting.

Experimental and Numerical Simulation Analysis of the Blocking Layer in an Electromagnetic Induction-Controlled Automated Steel Teeming System

Experimental and Numerical Simulation Analysis of the Blocking Layer in an Electromagnetic Induction-Controlled Automated Steel Teeming System

The Role of Heterogeneity and the Dynamics of Voluntary Contributions to Public Goods: An Experimental and Agent-Based Simulation Analysis

This paper examines the role of heterogeneous agents in the study of voluntary contributions to public goods. A human-subject experiment was conducted to classify agent types and determine their effects on contribution levels. Data from the experiment was used to build and calibrate an agent-based simulation model. The simulations display how different compositions of agent preference types affect the contribution levels. Findings indicate that the heterogeneity of cooperative preferences is an important determinant of a population’s contribution pattern.

Embedded Applications of MS-PSO-BP on Wind/Storage Power Forecasting

Higher proportion wind power penetration has great impact on grid operation and dispatching, intelligent hybrid algorithm is proposed to cope with inaccurate schedule forecast. Firstly, hybrid algorithm of MS-PSO-BP (Mathematical Statistics, Particle Swarm Optimization, Back Propagation neural network) is proposed to improve the wind power system prediction accuracy. MS is used to optimize artificial neural network training sample, PSO-BP (particle swarm combined with back propagation neural network) is employed on prediction error dynamic revision. From the angle of root mean square error (RMSE), the mean absolute error (MAE) and convergence rate, analysis and comparison of several intelligent algorithms (BP, RBP, PSO-BP, MS-BP, MS-RBP, MS-PSO-BP) are done to verify the availability of the proposed prediction method. Further, due to the physical function of energy storage in improving accuracy of schedule pre-fabrication, a mathematical statistical method is proposed to determine the optimal capacity of the storage batteries in power forecasting based on the historical statistical data of wind farm. Algorithm feasibility is validated by application of experiment simulation and comparative analysis.

Experiment and ANSYS simulation analysis for metal aluminum solid and fluid conversion

In this paper, study on metal aluminum solid and fluid conversion was carried out by using crucible resistance furnace, and observing the phenomenon of metal aluminum solid and fluid conversion. In the experiment, the same shape aluminum block was kept under the same heating rate and heated by the resistance furnace. The experimental results show that the melting point of metal aluminum is between 650°C and 660°C, and after the melting point, the metal aluminum began to melt when it maintained for a long period of time, however, when the temperature is higher than the melting point, the aluminum will melt very quickly. In addition, in ANSYS simulation, the solid aluminum melted completely at 670°C in 5430 seconds, much longer than the actual experiment, it due to the heating rate was faster, not in an ideal experimental environment and there is heat exchange with the outside world and convection, at the same time, the aluminum block may contain impurities, so the actual melting time could be shorter than the simulation. In this paper, it was explored for the liquid and solid conversion in depth, and had a certain actual value.

Failure Analysis of an Aluminum Chiller Pipe by Experimental Simulation and Stress Analysis

An explosion at a food processing plant was initially attributed during scene investigation to a separated butt weld in aluminum piping associated with an ammonia-based refrigeration system. The piping failed at a weld with no obvious gross plastic deformation and, on this basis primarily, was incorrectly determined to have failed by fatigue. A series of tests on exemplar welded pipe specimens was conducted to establish fractographic characteristics for the various failure modes. Finite element stress analyses were also conducted to assist in the fracture mode determination. The results of the exemplar tests and stress analyses demonstrated that the subject weld fracture occurred via a single-event overstress due to post-explosion collapse of the adjacent roof truss.