Self-diffraction appears when the strong laser goes through two-dimensional material suspension, and this spatial self-phase modulation (SPPM) phenomenon can be used to measure nonlinear optical parameters and achieve optical switch. At present, the mechanism of SPPM is still ambiguous. The debate mainly focuses on whether the phenomenon is caused by the nonlinear refractive index of the two-dimensional material or the thermal effect of the laser. The lack of theory limits the dimension of the phase modulation to the radius of the diffraction ring and the vertical imbalance. Therefore, it is urgent to establish a unified and universal SSPM theoretical system of two-dimensional material.

The 4-lobe aluminum alloy helical surface rotors are widely applied in industry, such as superchargers. Generally, the conventional manufacturing processes of aluminum alloy helical surface are time consuming and costly. To make the manufacturing processes more flexible and economical, the forward hot extrusion process is proposed to form the 4-lobe aluminum alloy helical surface rotors. In this work, we implement both simulations and experiments to the forming process of the helical surface, of which the material is 6063 aluminum alloy. The forward hot extrusion process is simulated with finite element method in DEFORM-3D. Based on the simulation method, the influences of different extrusion parameters, such as extrusion temperature, extrusion speed and extrusion ratio, on the extrusion process are studied. According to the numerical simulation results, the optimal case is chosen to carry out the experiment. Furthermore, the experimental results show that the surface is smooth; the toothed fill is full; the twist angle in the length direction is evenly distributed; the value of twist angle is roughly in line with the design angle, which is mainly due to the modified die structure, having a positive and significant effect on the increment of twist angle. Therefore, the twist angle has an increase of about 76%, which verifies the modified die structure.

Friction stir welding provides better retention of ductility and plasticity in comparison to fusion welding and it increases the stability against cracking. This study aims to enhance both the ductility and strength of the welded joints. Tool profile was found to play an important role in retaining ductility, understanding the metal flow behavior and determining the fracture initiating point. The microstructure of different regions in the onion ring was inferred to correlate the strength with the metal flow pattern. The onion ring pattern strengthened the weld nugget. Shoulder and taper threaded profile tool resulted in superior mechanical properties. Microhardness results confirmed that the fracture runs through low hardness areas such as heat affected zone and thermo-mechanically affected zone. The scanning electron microscopic images revealed elongated grains and dimples, justifying ductile mode of fracture.

Water leaching of As₂O₃ from metallurgical dust containing various metals was investigated, serving the purpose of dearsenization and simultaneous metal enrichment especially for indium. Effects of leaching temperature, liquid/solid ratio (LSR) and leaching time were studied. It was found that the initial dissolution was very fast but was then so inhibited by the increasingly dissolved As₂O₃, which makes it difficult to saturate enough arsenic in the leaching solution or in leaching out all the soluble arsenic with excess dosage of water within acceptable time (120 min). Only about 73% of As₂O₃ was extracted under the optimal conditions investigated. Two-step leaching showed similar trends and was thus unnecessary for improving As₂O₃ extraction. These observations could reasonably be accounted for the reversibility of the dissolution reaction. Kinetically, the leaching was described satisfactorily by the semi-empirical Avrami model with the apparent activation energy of 36.08 kJ/mol. The purity of the obtained product AS2O3 could reach 98.7%, while the indium could be enriched in the leaching residue without loss.

Aiming at dealing with the difficulty for traditional emergency rescue vehicle (ECV) to enter into limited rescue scenes, the electro-hydraulic steer-by-wire (SBW) system is introduced to achieve the multi-mode steering of the ECV. The overall structure and mathematical model of the SBW system are described at length. The fractional order proportional-integral-derivative (FOPID) controller based on fractional calculus theory is designed to control the steering cylinder’s movement in SBW system. The anti-windup problem is considered in the FOPID controller design to reduce the bad influence of saturation. Five parameters of the FOPID controller are optimized using the genetic algorithm by maximizing the fitness function which involves integral of time by absolute value error (ITAE), peak overshoot, as well as settling time. The time-domain simulations are implemented to identify the performance of the raised FOPID controller. The simulation results indicate the presented FOPID controller possesses more effective control properties than classical proportional-integral-derivative (PID) controller on the part of transient response, tracking capability and robustness.

Aiming at the issue of yaw and rollover stability control for off-road vehicles with non-pneumatic mechanical elastic wheel (MEW), an integrated control system based on fuzzy differential braking is developed. By simplifying the structure of the MEW, a corresponding fitting brush tire model is constructed and its longitudinal and lateral tire force expressions are set up, respectively. Then, a nonlinear vehicle simulation model with MEW is established to validate the proposed control scheme based on Carsim. The designed yaw and rollover control system is a two-level structure with the upper additional moment controller, which utilizes a predictive load transfer ratio (PLTR) as the rollover index. In order to design the upper integrated control algorithm, fuzzy proportional-integral-derivative (PID) is adopted to coordinate the yaw and rollover control, simultaneously. And the lower control allocator realizes the additional moment to the vehicle by differential braking. Finally, a Carsim-simulink co-simulation model is constructed, and simulation results show that the integrated control system could improve the vehicle yaw and roll stability, and prevent rollover happening.

Spur gears are widely used in the power transmission mechanism of several machines. Due to the transmitted torque, spur gears experience high stresses which could cause gear tooth failure by surface pitting or root fracture. Tip relief and other gear profile modification have been considered for reducing the induced stresses in the gear tooth. In this work, the influence of tip relief on stresses on a pair of identical spur gear was analyzed using commercial FEA software ANSYS, and formulae for estimating contact and bending stresses were derived. Three cases of gear sets were analyzed; a non-modified pair and another two sets with linear and parabolic tip relief profiles. The non-modified gear set frictionless contact stress was validated against the calculated AGMA pitting resistance, Hertzian contact stress and a reported contact stress value in the literature. The four methods agreed well with each other. Similarly, bending stress was also compared with the AGMA bending strength and Lewis bending stress for validation. Then, friction coefficient was varied from 0.0 to 0.3 with increment of 0.1. The gear contact stress increased up to 11% relative to the frictionless case, whereas bending stress decreased by 6%. Linear tip relief modification was carried out for increasing normalised tip relief values of 0.25 to 1.0 with increment of 0.25. The gear frictionless contact and bending stresses decreased by a maximum of 4% and 2%, respectively. Frictional contact stress increased by up to 7.1% and the bending stress is almost identical with the frictionless case. Parabolic tip relief was also carried out with similar normalised tip relief values. Frictionless contact stress decreased by 5% while frictional contact stress increased by up to 11.5% and the bending stress is also almost identical with the frictionless case. Finally, four formulae were introduced for estimating the contact and bending stresses for a tip modified spur gear.

This research develops a new mathematical modeling method by combining industrial big data and process mechanism analysis under the framework of generalized additive models (GAM) to generate a practical model with generalization and precision. Specifically, the proposed modeling method includes the following steps. Firstly, the influence factors are screened using mechanism knowledge and data-mining methods. Secondly, the unary GAM without interactions including cleaning the data, building the sub-models, and verifying the sub-models. Subsequently, the interactions between the various factors are explored, and the binary GAM with interactions is constructed. The relationships among the sub-models are analyzed, and the integrated model is built. Finally, based on the proposed modeling method, two prediction models of mechanical property and deformation resistance for hot-rolled strips are established. Industrial actual data verification demonstrates that the new models have good prediction precision, and the mean absolute percentage errors of tensile strength, yield strength and deformation resistance are 2.54%, 3.34% and 6.53%, respectively. And experimental results suggest that the proposed method offers a new approach to industrial process modeling.

The construction efficiency and quality of tunnel boring machines (TBMs) is largely determined by the service life of cutting tools, which is the result of contact loads in the crushed zone between cutter ring and rock. In this paper, a series of rock breaking tests were conducted with a 216 mm diameter disc cutter and concrete samples. Based on the superposition principle, the distribution of contact loads between disc cutter and rock were obtained by using the truncated singular value decomposition (TSVD). The results show that both the peak value and the whole numerical distribution of the radial strains on the cutter ring increase with the increase of the penetration. The distribution curves of the contact loads show an approximate parabola going downwards, which indicates contact loads are more concentrated. The front non-loading area with a ratio from 1.8% to 5.4% shows an increasing trend with the increase of penetration. However, the change of rear non-loading area is not obvious. It is believed that the conclusions have guidance for the study of rock breaking mechanism and manufacturing process of the disc cutter.

Combining refined composite multiscale fuzzy entropy (RCMFE) and support vector machine (SVM) with particle swarm optimization (PSO) for diagnosing roller bearing faults is proposed in this paper. Compared with refined composite multiscale sample entropy (RCMSE) and multiscale fuzzy entropy (MFE), the smoothness of RCMFE is superior to that of those models. The corresponding comparison of smoothness and analysis of validity through decomposition accuracy are considered in the numerical experiments by considering the white and 1/f noise signals. Then RCMFE, RCMSE and MFE are developed to affect extraction by using different roller bearing vibration signals. Then the extracted RCMFE, RCMSE and MFE eigenvectors are regarded as the input of the PSO-SVM to diagnose the roller bearing fault. Finally, the results show that the smoothness of RCMFE is superior to that of RCMSE and MFE. Meanwhile, the fault classification accuracy is higher than that of RCMSE and MFE.

The vibration signals of multi-fault rolling bearings under nonstationary conditions are characterized by intricate modulation features, making it difficult to identify the fault characteristic frequency. To remove the time-varying behavior caused by speed fluctuation, the phase function of target component is necessary. However, the frequency components induced by different faults interfere with each other. More importantly, the complex sideband clusters around the characteristic frequency further hinder the spectrum interpretation. As such, we propose a demodulation spectrum analysis method for multi-fault bearing detection via chirplet path pursuit. First, the envelope signal is obtained by applying Hilbert transform to the raw signal. Second, the characteristic frequency is extracted via chirplet path pursuit, and the other underlying components are calculated by the characteristic coefficient. Then, the energy factors of all components are determined according to the time-varying behavior of instantaneous frequency. Next, the final demodulated signal is obtained by iteratively applying generalized demodulation with tunable E-factor and then the band pass filter is designed to separate the demodulated component. Finally, the fault pattern can be identified by matching the prominent peaks in the demodulation spectrum with the theoretical characteristic frequencies. The method is validated by simulated and experimental signals.

Nowadays, more and more Android developers prefer to seek help from Q&A website like Stack Overflow, despite the rich official documentation. Several researches have studied the limitations of the official application programming interface (API) documentations and proposed approaches to improve them. However, few of them digged into the requirements of the third-party developers to study this. In this work, we gain insight into this question from multidimensional perspectives of API developers and API users by a kind of cross-validation. We propose a hybrid approach, which combines manual inspection on artifacts and online survey on corresponding developers, to explore the different focus between these two types of stakeholders. In our work, we manually inspect 1000 posts and receive 319 questionnaires in total. Through the mutual verification of the inspection and survey process, we found that the users are more concerned with the usage of API, while the official documentation mainly provides functional description. Furthermore, we identified 9 flaws of the official documentation and summarized 12 aspects (from the content to the representation) for promotion to improve the official API documentations.

Crustal stresses play an important role in both exploration and development in the oil and gas industry. However, it is difficult to simulate crustal stress distributions accurately, because of the incompatibilities that exist among different software. Here, a series of algorithms is developed and integrated in the Petrel2ANSYS to carry out two-way conversions between the 3D attribute models that employ corner-point grids used in Petrel and the 3D finite-element grids used in ANSYS. Furthermore, a modified method of simulating stress characteristics and analyzing stress fields using the finite-element method and multiple finely resolved 3D models is proposed. Compared to the traditional finite-element simulation-based approach, which involves describing the heterogeneous within a rock body or sedimentary facies in detail and simulating the stress distribution, the single grid cell-based approach focuses on a greater degree on combining the rock mechanics described by 3D corner-point grid models with the finely resolved material characteristics of 3D finite-element models. Different models that use structured and unstructured grids are verified in Petrel2ANSYS to assess the feasibility. In addition, with minor modifications, platforms based on the present algorithms can be extended to other models to convert corner-point grids to the finite-element grids constructed by other software.

In this paper, crashworthiness performance of multi-cell conical tubes with new sectional configuration design (i.e. square, hexagonal, octagonal, decagon and circular) has been evaluated under axial and three different oblique loads. The same weight conical tubes were comparatively studied using an experimentally validated finite element model generated in LS-DYNA. Complex proportional assessment (COPRAS) method was then employed to select the most efficient tube using two conflicting criteria, namely peak collapse force (PCF) and energy absorption (EA). From the COPRAS calculations, the multi-cell conical tube with decagonal cross-section (MCDT) showed the best crashworthiness performance. Furthermore, the effects of possible number of inside ribs on the crashworthiness of the decagonal conical tubes were also evaluated, and the results displayed that the tubes performed better as the number of ribs increased. Finally, parameters (the cone angle, θ, and ratio of the internal tube size to the external one, S) of MCDT were optimized by adopting artificial neural networks (ANN) and genetic algorithm (GA) techniques. Based on the multi-objective optimization results, the optimum dimension parameters were found to be θ=7.9°, S=0.46 and θ=8°, S=0.74 from the minimum distance selection (MDS) and COPRAS methods, respectively.

To improve magnetotelluric (MT) nonlinear inversion accuracy and stabilitythis work introduces the deep belief network (DBN) algorithm. Firstlya network frame is set up for training in different 2D MT models. The network inputs are the apparent resistivities of known modelsand the outputs are the model parameters. The optimal network structure is achieved by determining the numbers of hidden layers and network nodes. Secondlythe learning process of the DBN is implemented to obtain the optimal solution of network connection weights for known geoelectric models. Finallythe trained DBN is verified through inversion testsin which the network inputs are the apparent resistivities of unknown modelsand the outputs are the corresponding model parameters. The experiment results show that the DBN can make full use of the global searching capability of the restricted Boltzmann machine (RBM) unsupervised learning and the local optimization of the back propagation (BP) neural network supervised learning. Comparing to the traditional neural network inversionthe calculation accuracy and stability of the DBN for MT data inversion are improved significantly. And the tests on synthetic data reveal that this method can be applied to MT data inversion and achieve good results compared with the least-square regularization inversion.

In this work, a system for recognition of newspaper printed in Gurumukhi script is presented. Four feature extraction techniques, namely, zoning features, diagonal features, parabola curve fitting based features, and power curve fitting based features are considered for extracting the statistical properties of the characters printed in the newspaper. Different combinations of these features are also applied to improve the recognition accuracy. For recognition, four classification techniques, namely, k-NN, linear-SVM, decision tree, and random forest are used. A database for the experiments is collected from three major Gurumukhi script newspapers which are Ajit, Jagbani and Punjabi Tribune. Using 5-fold cross validation and random forest classifier, a recognition accuracy of 96.19% with a combination of zoning features, diagonal features and parabola curve fitting based features has been reported. A recognition accuracy of 95.21% with a partitioning strategy of data set (70% data as training data and remaining 30% data as testing data) has been achieved.

Effective fault detection techniques can help flotation plant reduce reagents consumption, increase mineral recovery, and reduce labor intensity. Traditional, online fault detection methods during flotation processes have concentrated on extracting a specific froth feature for segmentation, like color, shape, size and texture, always leading to undesirable accuracy and efficiency since the same segmentation algorithm could not be applied to every case. In this work, a new integrated method based on convolution neural network (CNN) combined with transfer learning approach and support vector machine (SVM) is proposed to automatically recognize the flotation condition. To be more specific, CNN function as a trainable feature extractor to process the froth images and SVM is used as a recognizer to implement fault detection. As compared with the existed recognition methods, it turns out that the CNN-SVM model can automatically retrieve features from the raw froth images and perform fault detection with high accuracy. Hence, a CNN-SVM based, real-time flotation monitoring system is proposed for application in an antimony flotation plant in China.

One-way roads have potential for improving vehicle speed and reducing traffic delay. Suffering from dense road network, most of adjacent intersections' distance on one-way roads becomes relatively close, which makes isolated control of intersections inefficient in this scene. Thus, it is significant to develop coordinated control of multiple intersection signals on the one-way roads. This paper proposes a signal coordination control method that is suitable for one-way arterial roads. This method uses the cooperation technology of the vehicle infrastructure to collect intersection traffic information and share information among the intersections. Adaptive signal control system is adopted for each intersection in the coordination system, and the green light time is adjusted in real time based on the number of vehicles in queue. The offset and clearance time can be calculated according to the real-time traffic volume. The proposed method was verified with simulation results by VISSiM traffic simulation software. The results compared with other methods show that the coordinated control method proposed in this paper can effectively reduce the average delay of vehicles on the arterial roads and improve the traffic efficiency.

The gas-liquid two-phase swirl flow can increase the gas-liquid two-phase contact area and enhance the heat and mass transfer efficiency between gas and liquid. The swirl flow has important practical application value for promoting gas hydrate formation and ensuring the flow safe of natural gas hydrate slurry. The experimental section was made of plexiglass pipe and the experimental medium was air and water. The flow pattern of the gas-liquid two-phase swirl flow in the horizontal pipe was divided, according to a high-definition camera and the overall characteristics of the gas-liquid interface. The flow pattern map of the gas-liquid two-phase swirl flow in a horizontal pipe was studied. The influence of the flow velocity and vane parameters on pressure drop was investigated. Two types of gas-liquid two-phase swirl flow pressure drop models was established. The homogeneous-phase and split-phase pressure drop models have good prediction on swirl bubble flow, swirl dispersed flow, swirl annular flow and swirl stratified flow, and the predictive error band is not more than 20%.

Nanofluids have attracted many scientists due to their remarkable thermophysical properties. Small percentage of nanoparticles when added to conventional fluid significantly enhances the heat transfer features. Sustainability and efficiency of nanomaterials have key role in the advancement of nanotechnology. This article analyzes the Hall, Ohmic heating and velocity slip effects on the peristalsis of nanofluid. Convective boundary conditions and heat generation/absorption are considered to facilitate the heat transfer characteristics. Governing equations for the peristaltic flow through a curved channel are derived in curvilinear coordinates. The equations are numerically solved under the assumption of long wavelength and small Reynold number. It has been observed that nanofluid enhances the heat transfer rate and reduces the fluid temperature. Hartman number and Hall parameter show reverse behavior in fluid motion and heat transfer characteristics. In the presence of velocity slip, the pressure gradient rapidly decreases and dominant effect is seen in narrow portion of channel.

To evaluate the effect of treating long cracks with the impact crack-closure retrofit (ICR) technique, three rib-to-deck welded specimens with a crack length of about 100 mm were tested. The metallographic structure, crack section, crack propagation life, and stress variation were analyzed. Finite-element models were also developed, and some optimal values of certain parameters are suggested according to the simulated results. The results show that new crack sources are generated on both sides of the ICR-treated region because of the stress distribution. The fatigue lives of cracked specimens with long cracks are significantly improved by the technique. Considerable residual compressive stress is also induced, and so it is suggested that the optimal impact angle to be applied to real bridges should be 70°. The stress at the weld root is distributed uniformly with the crack closed, and the optimal crack-closure depth is 4 mm. To evaluate the effect of different crack-closure depths in tests, it is recommended that a hot-spot stress method which is extrapolated by three reference points should be adopted.

By spraying concrete on inner surface, air-supported fabric structures can be used as formwork to construct reinforced concrete shell structures. The fabric formwork has the finished form of concrete structure. Large deviation from the desired shape of concrete shells still remains as central problem due to dead weight of concrete and less stiffness of fabric formwork. Polyurethane can be used not only as a bonding layer between fabrics and concrete but also as an additional stiffening layer. However, there is little research on mechanical behaviors of the polyurethane shell structure. This paper presents experimental studies on an inflated fabric model with and without polyurethane, including relief pressure tests, vertical loading tests and horizontal loading tests. Experimental results show that the additional polyurethane layer can significantly enhance the stiffness of the fabric formwork. Compared with the experiment, a numerical model using shell layered finite elements has a good prediction. The reinforcement by polyurethane to improve stiffness of air-supported fabric formwork is expected to be considered in the design and construction of the concrete shell, especially dealing with the advance of shape-control.

A binary eutectic mixture composed of tetradecanol (TD) and myristic acid (MA) was maximally absorbed into the microstructures of expanded perlite (EP) and expanded vermiculite (EVMT), respectively, through a self-made vacuum adsorption roller to prepare phase change material (PCM) particle (PCP). Then EP and EVMT-based composite PCM plates were respectively fabricated through a mold pressing method. The thermal property, chemical stability, microstructure and durability were characterized by differential scanning calorimeter (DSC), Fourier transform infrared spectroscope (FT-IR), scanning electron microscope (SEM) and thermal cycling tests, respectively. The results show that both PCPs have high latent heats with 110 J/g for EP-based PCP and more than 130 J/g for EVMT-based PCP, compact microstructure without PCM leakage, stable chemical property and good durability. The research results have proved the feasibility for the vacuum adsorption roller used in the composite PCM fabrication. Results of thermal storage performance experiment indicate that the fabricated PCM plates have better thermal inertia than common building materials, and the thermal storage performance of PCM plates has nonlinearly changed with outside air velocity and temperature increase. Therefore, PCM plates show a significant potential for the practical application of building thermal storage.

The current study aims to evaluate the dynamic response of stabilized cohesive soil using an enzymatic preparation in terms of resilient modulus. We ran a series of resilient modulus testing according to AASHTO T307 on three types of cohesive soil treated with an enzymatic preparation to investigate its potential on roads construction. The results show significant improvement in the resilient modulus values, estimated at 1.4 to 4.4 times that observed for the untreated soil. Because of the complexity in conducting the resilient modulus measurement, we did a regression analysis to produce reliable correlation formula to predict the resilient modulus for untreated and stabilised soil samples involving stress state. The resilient modulus values for the subgrade materials at the anticipated field stresses were determined using a universal model. The enzymatic preparation was applied in pavement of a sample road and evaluated using the plate load test. SEM analysis for soil samples shows improvement in the soil compaction via reduction of voids between soil particles. XRD analysis shows no major structural changes in the treated soils. The enzymatic preparation contains 43 mg/mL of proteins. We used the SDS-PAGE (sodium dodecyl sulphate polyacrylamide gel electrophoresis) technique to identify the main protein components; however, the presence of interfering materials (surfactants) hinders the separation.

This article presents an experimental study on the flexural performance of reinforced concrete (RC) beams with fiber reinforced cementitious composites (FRCC) and hybrid fiber reinforced cementitious composites (HFRCC) in the hinge portion. Beam specimens with moderate confinement were used in the study and tested under monotonic loading. Seven diverse types of FRCC including hybrid composites using fibers in different profiles and in different volumes are employed in this study. Companion specimens such as cylindrical specimens and prism specimens are also used to study the physical properties of composites employed. The moment-curvature, stiffness behavior, ductility, crack pattern and modified flexural damage ratio are the main factors considered in this study to observe the efficacy of the employed hybrid composites. The experimental outputs demonstrate the improved post yield behavior with less rate of stiffness degradation and better damage tolerance capacity than conventional technique.