The structural health status of Hunan Road Bridge during its two-year service period from April 2015 to April 2017 was studied based on monitored data. The Hunan Road Bridge is the widest concrete self-anchored suspension bridge in China at present. Its structural changes and safety were evaluated using the health monitoring data, which included deformations, detailed stresses, and vibration characteristics. The influences of the single and dual effects comprising the ambient temperature changes and concrete shrinkage and creep (S&C) were analyzed based on the measured data. The ANSYS beam finite element model was established and validated by the measured bridge completion state. The comparative analyses of the prediction results of long-term concrete S&C effects were conducted using CEB-FIP 90 and B3 prediction models. The age-adjusted effective modulus method was adopted to simulate the aging behavior of concrete. Prestress relaxation was considered in the stepwise calculation. The results show that the transverse deviations of the towers are noteworthy. The spatial effect of the extra-wide girder is significant, as the compressive stress variations at the girder were uneven along the transverse direction. General increase and decrease in the girder compressive stresses were caused by seasonal ambient warming and cooling, respectively. The temperature gradient effects in the main girder were significant. Comparisons with the measured data showed that more accurate prediction results were obtained with the B3 prediction model, which can consider the concrete material parameters, than with the CEB-FIP 90 model. Significant deflection of the midspan girder in the middle region will be caused by the deviations of the cable anchoring positions at the girder ends and tower tops toward the midspan due to concrete S&C. The increase in the compressive stresses at the top plate and decrease in the stresses at the bottom plate at the middle midspan will be significant. The pre-deviations of the towers toward the sidespan and pre-lift of the midspan girder can reduce the adverse influences of concrete S&C on the structural health of the self-anchored suspension bridge with extra-wide concrete girder.

The luminance in the road tunnel threshold zone attracts broad attention due to its enormous energy consumption and direct influence on tunnel transportation security. Current lighting design methods in threshold zones mostly adopt the reduction coefficient method. However, the determination of reduction coefficient k simply considers tunnel design speed and flow rate, while excluding outside tunnel luminance and threshold zone color temperature and luminance, which have a major impact on driver visual adaptation. Existing problems in the determination of k value are analyzed; a visual performance experiment is utilized; and the reaction time of drivers in changeable outside tunnel luminance and threshold zone color temperature and luminance conditions is obtained; thus, the equations concerning reduction coefficient variation law are derived. In the end, a comparative analysis is made of the k values of the reduction coefficient stipulated by various norms under different color temperature conditions.

The key parameters of the adhesive layer of a reinforcing patch are of great significance and affect the ability to suppress crack propagation in an Al–Li alloy patch-reinforced structure. This paper proposes a method to determine the key parameters of the adhesive layer of adhesively bonded joints in the Al–Li alloy patch-reinforced structure. A zero-thickness cohesive zone model (CZM) was selected to simulate the adhesive layer’s fracture process, and an orthogonal simulation was designed to compare against the test results. A three-dimensional progressive damage model of an Al–Li alloy patch-reinforced structure with single-lap adhesively bonded joints was developed. The simulation’s results closely agree with the test results, demonstrating that this method of determining the key parameters is likely accurate. The results also verify the correctness of the cohesive strength and fracture energy, the two key parameters of the cohesive zone model. The model can accurately predict the strength and fracture process of adhesively bonded joints, and can be used in research to suppress crack propagation in Al–Li alloy patch-reinforced structures.

Taking advantage of the new standard HTML5, we designed an online tool called a browser/server-based glaucoma image database builder (BGIDB) for the demarcation of the optic disk and cup’s ellipse-like boundaries. The B-spline interpolation algorithm is used, and a specially designed algorithm is proposed for classifying the disease grade according to the disc damage likelihood scale criterion, which is correlated strongly with the glaucoma process by quantity. This tool exhibits the best performance with a low overlapping error of 4.34% for the optic disk demarcation and 8.31% for the optic cup demarcation. It also has preferable time-consuming as compared to other tools and is a cross-platform system. This tool has already been utilized in building the ophthalmic image database in the cooperation of Center for Ophthalmic Imaging Research and The Second Xiangya Hospital.

The fatigue performance of a workpiece depends on its surface quality. In traditional fatigue life prediction, the effect of surface quality is commonly accounted for by using empirical correction factors, which is imprecise when safety is of great concern. For surface quality, the surface topography is an important parameter, which introduces stress concentration that reduces the fatigue life. It is not feasible to test the stress concentration of different surface topographies. On the one hand, it is time-consuming and high-cost, and on the other hand, it cannot reflect the general statistical characteristics. With the help of surface reconstruction technology and interpolation method, a more efficient and economic approach is proposed, where FE simulation of workpiece with the reconstructed surface topography is used as a foundation for fatigue life prediction. The relationship between surface roughness (S_a) and fatigue life of the workpiece is studied with the proposed approach.

A low-temperature superconducting quantum interference device (low-Tc SQUID) can improve the depth of exploration. However, a low-Tc SQUID may lose its lock owing to oscillations in the current or the occurrence of spikes when the transmitter is switched off. If a low-Tc SQUID loses its lock, it becomes impossible for the low-Tc SQUID TEM system to function normally and stably for a long period of time. This hinders the practical use of the system. In field experiments, the transmitting current is accurately measured, the voltage overshoot and current spike data are recorded, and the gradient of the primary magnetic field at the center of the transmitting loop is calculated. After analyzing the results of field experiments, it was found that when the gradient of the primary magnetic field far exceeds the slew rate of a low-Tc SQUID, the low-Tc SQUID loses its lock. Based on the mechanisms of the transmitting oscillation, an RC serial and multi-parallel capacity snubber circuit used to suppress such oscillation is proposed. The results of simulation and field experiments show that, when using a 100 m×100 m transmitting loop, the gradient of the primary magnetic field is suppressed from 101.4 to 2.4 mT/s with a transmitting current of 40 A, and from 29.6 to 1.4 mT/s with a transmitting current of 20 A. Therefore, it can be concluded that the gradient of the primary magnetic field is below the slew rate of a low-Tc SQUID after adopting the proposed RC serial and multi-parallel capacity snubber circuit. In conclusion, the technique proposed in this paper solves the problem of a lost lock of a low-Tc SQUID, ensuring that the low-Tc SQUID TEM system functions stably for a long period of time, and providing technical assurance for ground TEM exploration at an additional depth.

Incorporating aluminum particles into viscous medium was proposed to improve the thermal conductivity of the viscous medium and the efficiency of warm viscous pressure forming (WVPF) process. The influence of aluminum particles on a viscous medium was investigated through settling, thermal conductivity, and compression experiments. Warm viscous pressure bulging (WVPB) experiments were conducted on polyetherimide (PEI) and AZ31B magnesium alloy sheets to determine the influence of the aluminum particles size and fraction on the forming efficiency and formed specimens based on the heating preparation times and profile curves, wall thicknesses and surface roughness values of the bulging specimens. The results show that the thermal conductivity of the viscous medium and the WVPF efficiency can be greatly improved via the addition aluminum particles with appropriate size and fraction under certain temperature condition, but have less influence on other properties of viscous medium.

This study presents experimental and numerical investigations of simply supported steel reinforced concrete (RC) beams under fire. The temperature field of cross sections, the vertical deflection at mid-span, and specifically the axial expansion displacement at beam-ends were measured during the fire tests. A novel finite element (FE) model of a RC beam under fire was developed, in which the water loss in the heat transfer analysis and the concrete transient strain in the mechanical analysis were considered. Based on the validated FE model proposed in this study, parametric studies were conducted to investigate the effects of the beam type, the protective layer thickness, and the load ratio on the thermal and mechanical behavior of simply supported RC beams. It was found that greater fire resistance and fire performance of girder beams in comparison to secondary beams contributed to the non-structural reinforcements, which effectively compensated for the reduced tensile capacities of structural reinforcements because of the degradation of the material properties. In addition, the history of normal stress distributions of concrete under fire can be divided into three phases: expansion, stress redistribution and plateau phases.

To study the rock breaking method under the free surface induced by disc cutter, the rock breaking simulations were first conducted based on the discrete element method, and the dynamic process of rock breaking under the free surface was studied including stressed zone, crush zone, crack initiation and propagation. Then the crack propagation conditions, specific energy, etc. under different free surface distance (S) were also investigated combined with linear cutting experiments. The results show that the rock breaking process under the free surface induced by disc cutter is dominated by tension failure mode. There exists a critical S to promote crack propagation to free surface effectively. And this rock breaking method can improve the rock breaking force and breaking efficiency significantly when proper.

Reduction of Cr(VI) using zero-valent iron (ZVI) could not only decrease the amounts of chemicals used for reduction, but also decrease the discharge of sludge. In order to find a desirable ZVI material, reduction of Cr(VI) with a relative high concentration using different kinds of ZVI powders (mainly carbon differences) including reduced Fe, grey cast iron, pig iron, nodular pig iron was carried out. Parameters such as ZVI dosage, type and size affecting on Cr(VI) reduction were firstly examined and grey cast iron was selected as a preferable reducing material, followed by pig iron. Additionally, it was found that the parameters had significant influences on experimental kinetics. Then, morphology and composition of the sample before and after reaction were characterized by SEM, EPMA and XPS analyses to disclose carbon effect on the reducibility. In order to further interpret reaction mechanism, different reaction models were constructed. It was revealed that not only the carbon content could affect the Cr(VI) reduction, but also the carbon structure had an important effect on its reduction.

We introduce the artificial fish swarm algorithm for heading motion model identification and control parameter optimization problems for the “Ocean Rambler” unmanned wave glider (UWG). First, under certain assumptions, the rigid-flexible multi-body system of the UWG was simplified as a rigid system composed of “thruster + float body”, based on which a planar motion model of the UWG was established. Second, we obtained the model parameters using an empirical method combined with parameter identification, which means that some parameters were estimated by the empirical method. In view of the specificity and importance of the heading control, heading model parameters were identified through the artificial fish swarm algorithm based on tank test data, so that we could take full advantage of the limited trial data to factually describe the dynamic characteristics of the system. Based on the established heading motion model, parameters of the heading S-surface controller were optimized using the artificial fish swarm algorithm. Heading motion comparison and maritime control experiments of the “Ocean Rambler” UWG were completed. Tank test results show high precision of heading motion prediction including heading angle and yawing angular velocity. The UWG shows good control performance in tank tests and sea trials. The efficiency of the proposed method is verified.

Copper porous materials have been manufactured by the method of powder metallurgy. Electrolytic copper powders and atomized copper powders are used as matrix material. Methylcellulose and paraffin are used as porogen. The influence of porogen type and copper powder morphology on the property of copper porous materials is investigated as well. The results show that copper porous materials with paraffin as porogen have lower porosity and permeability compared with materials using methylcellulose as porogen, due to the different pore-forming mechanisms. The pore forming mechanism of methylcellulose is thermal decomposition, while the pore forming mechanism of paraffin is melting–evaporation. The morphology of copper powders affects the contact state between adjacent powders, which further influence the sintering shrinkage. The porous materials using arborescent copper powders as matrix have lower porosity, smaller pore size and lower permeability, compared with materials with atomized copper powders as matrix.

Power-line interference is one of the most common noises in magnetotelluric (MT) data. It usually causes distortion at the fundamental frequency and its odd harmonics, and may also affect other frequency bands. Although trap circuits are designed to suppress such noise in most of the modern acquisition devices, strong interferences are still found in MT data, and the power-line interference will fluctuate with the changing of load current. The fixed trap circuits often fail to deal with it. This paper proposes an alternative scheme for power-line interference removal based on frequency-domain sparse decomposition. Firstly, the fast Fourier transform of the acquired MT signal is performed. Subsequently, a redundant dictionary is designed to match with the power-line interference which is insensitive to the useful signal. Power-line interference is separated by using the dictionary and a signal reconstruction algorithm of compressive sensing called improved orthogonal matching pursuit (IOMP). Finally, the frequency domain data are switched back to the time domain by the inverse fast Fourier transform. Simulation experiments and real data examples from Lu-Zong ore district illustrate that this scheme can effectively suppress the power-line interference and significantly improve data quality. Compared with time domain sparse decomposition, this scheme takes less time consumption and acquires better results.

Cooperative driving around intersections has aroused increasing interest in the last five years. Meanwhile, driving safety in non-signalized intersections has become an issue that has attracted attention globally. In view of the potential collision risk when more than three vehicles approach a non-signalized intersection from different directions, we propose a driving model using cooperative game theory. First, the characteristic functions of this model are primarily established on each vehicle’s profit function and include safety, rapidity and comfort indicators. Second, the Shapley theorem is adopted, and its group rationality, individual rationality, and uniqueness are proved to be suitable for the characteristic functions of the model. Following this, different drivers’ characteristics are considered. In order to simplify the calculation process, a zero-mean normalization method is introduced. In addition, a genetic algorithm method is adopted to search an optimal strategy set in the constrained multi-objective optimization problem. Finally, the model is confirmed as valid after simulation with a series of initial conditions.

We reported the fabrication of highly porous graphene/TiO₂ composite nanofibers in the form of a nonwoven mat by electrospinning followed by calcination in air at 450 °C. The graphene can uniformly disperse in highly porous TiO₂ nanofibers. The highly porous graphene/TiO₂ composite nanofibers exhibited excellent catalytic activities. The new method for producing graphene/TiO₂ composite nanofibers is versatile and can be extended to fabricate various types of metal oxide and graphene nanocomposites.

The technological mineralogy of the potash feldspar was investigated and a new collector named Yb105 was adopted to remove iron from potash feldspar ores. The technological mineralogy results indicate that the main components of the ore were feldspar, sericite, quartz and kaolinite, and iron mainly existed in limonite and hematite, most of which can be removed by beneficiation. The results show the benzohydroxamic acid can not only increase the recovery of iron and reduce the consumption of oleic acid collector, but also enhance the collecting performance of oleic acid at low temperature, which can realize the flotation of the ores at a low temperature and play an important role in saving energy to some extent. Compared with oleic oil, the benzohydroxamic acid had a great advantage in removing iron from potash feldspar, a potash feldspar concentrate with Fe grade of 0.23%, K₂O grade of 12.59% and Na₂O grade of 0.26% was obtained by flotation with Yb105 as collector, and the yield of the concentrate was 82.55%.

In view of the structure and action behavior of mechatronic systems, a method of searching fault propagation paths called maximum-probability path search (MPPS) is proposed, aiming to determine all possible failure propagation paths with their lengths if faults occur. First, the physical structure system, function behavior, and complex network theory are integrated to define a system structural-action network (SSAN). Second, based on the concept of SSAN, two properties of nodes and edges, i.e., the topological property and reliability property, are combined to define the failure propagation property. Third, the proposed MPPS model provides all fault propagation paths and possible failure rates of nodes on these paths. Finally, numerical experiments have been implemented to show the accuracy and advancement compared with the methods of Function Space Iteration (FSI) and the algorithm of Ant Colony Optimization (ACO).

Because of its ease of implementation, a linear PID controller is generally used to control robotic manipulators. Linear controllers cannot effectively cope with uncertainties and variations in the parameters; therefore, nonlinear controllers with robust performance which can cope with these are recommended. The sliding mode control (SMC) is a robust state feedback control method for nonlinear systems that, in addition having a simple design, efficiently overcomes uncertainties and disturbances in the system. It also has a very fast transient response that is desirable when controlling robotic manipulators. The most critical drawback to SMC is chattering in the control input signal. To solve this problem, in this study, SMC is used with a boundary layer (SMCBL) to eliminate the chattering and improve the performance of the system. The proposed SMCBL was compared with inverse dynamic control (IDC), a conventional nonlinear control method. The kinematic and dynamic equations of the IRB-120 robot manipulator were initially extracted completely and accurately, and then the control of the robot manipulator using SMC was evaluated. For validation, the proposed control method was implemented on a 6-DOF IRB-120 robot manipulator in the presence of uncertainties. The results were simulated, tested, and compared in the MATLAB/Simulink environment. To further validate our work, the results were tested and confirmed experimentally on an actual IRB-120 robot manipulator.

Most research on anomaly detection has focused on event that is different from its spatial-temporal neighboring events. It is still a significant challenge to detect anomalies that involve multiple normal events interacting in an unusual pattern. In this work, a novel unsupervised method based on sparse topic model was proposed to capture motion patterns and detect anomalies in traffic surveillance. scale-invariant feature transform (SIFT) flow was used to improve the dense trajectory in order to extract interest points and the corresponding descriptors with less interference. For the purpose of strengthening the relationship of interest points on the same trajectory, the fisher kernel method was applied to obtain the representation of trajectory which was quantized into visual word. Then the sparse topic model was proposed to explore the latent motion patterns and achieve a sparse representation for the video scene. Finally, two anomaly detection algorithms were compared based on video clip detection and visual word analysis respectively. Experiments were conducted on QMUL Junction dataset and AVSS dataset. The results demonstrated the superior efficiency of the proposed method.

Gob-area roof rupture movement is a key disturbance factor for gob-side entry retaining. The characteristics of gob-area sequential roof collapse of overlying strata and superposed disturbance mechanism for gob-side entry retaining are obtained via physical simulation and theoretical analysis, in which the scope of disturbed strata is enlarged from main roof to fracture zone. The experiment reveals that as a working face advances, roof strata sequentially collapse from bottom to top and produce multiple disturbances to gob-side entry retaining. Key strata among the overlying strata control each collapse. Main roof subsidence is divided into three stages: flexure subsidence prior to rupture, rotational subsidence during rupture and compressive subsidence after rupture. The amounts of deformation evident in each of the three stages are 15%, 55% and 30%, respectively. After the master stratum collapses, main roof subsidence approaches its maximum value. The final span of the key stratum determines the moment and cycling of gob-side entry retaining disturbances. Main roof subsidence influences the load on the filling wall. The sequential roof collapse of overlying strata results in fluctuations in the gob-side entry retaining deformation. Calculation formulae for the final span of the key stratum and the filling wall load are obtained via theoretical analysis. A control method for the stability of the gob-side entry retaining’s surrounding rock is proposed, which includes 3 measures: a “dual-layer” proactive anchorage support, roadside filling with dynamic strength matching and auxiliary support during disturbance. Finally, the gob-side entry retaining of the Xiaoqing mine E1403 working face is presented as an engineering case capable of verifying the validity of the research conclusions.

Based on the nonlinear Mohr-Coulomb failure criterion and the associated flow rules, the three-dimensional (3-D) axisymmetric failure mechanism of shallow horizontal circular plate anchors that are subjected to the ultimate pullout capacity (UPC) is determined. A derivative function of the projection function for projecting the 3-D axisymmetric failure surface on plane is deduced using the variation theory. By using difference principle, the primitive function of failure surface satisfying boundary condition and numerical solution to its corresponding ultimate pullout capacity function are obtained. The influences of nonlinear Mohr-Coulomb parameters on UPC and failure mechanism are studied. The result shows that UPC decreases with dimensionless parameter m and uniaxial tensile strength increases but increases when depth and radius of plate anchor, surface overload, initial cohesion, geomaterial density and friction angle increase. The failure surface is similar to a symmetrical spatial funnel, and its shape is mainly determined by dimensionless parameter m; the surface damage range expands with the increase of radius and depth of the plate anchor as well as initial cohesion but decreases with the increase of dimensionless parameter m and uniaxial tensile strength as well as geomaterial density. As the dimensionless parameter m=2.0, the numerical solution of UPC based on the difference principle is proved to be feasible and effective through the comparison with the exact solution. In addition, the comparison between solutions of UPC computed by variation method and those computed by upper bound method indicate that variation method outperforms upper bound method.

Short suspension system has an indispensable effect on vehicle handling and ride, so, optimization of vehicle suspension system is one of the most effective methods, which could considerably enhance the vehicle stability and controllability. Motion control, stability maintenance and ride comfort improvement are fundamental issues in design of suspension system of off-road vehicles. In this work, a dependent suspension system mostly used in off-road vehicles is modeled using Trucksim software. Then, geometric parameters of suspension system are optimized using integrated anti-roll bar and coiling spring in a way that ride comfort, handling and stability of vehicle are improved. The simulation results of suspension system and variations of geometric parameters due to road roughness and different steering angles are presented in Trucksim and effects of optimization of suspension system during various driving maneuvers in both optimized and un-optimized conditions are compared. The simulation results indicate that the type of suspension system and geometric parameters have significant effect on vehicle performance.