Aluminium alloys generally present low weldability by traditional fusion welding process. Development of the friction stir welding (FSW) has provided an alternative improved way of producing aluminium joints in a faster and reliable manner. The quality of a weld joint is stalwartly influenced by process parameter used during welding. An approach to develop a mathematical model was studied for predicting and optimizing the process parameters of dissimilar aluminum alloy (AA6351 T6-AA5083 H111) joints by incorporating the FSW process parameters such as tool pin profile, tool rotational speed welding speed and axial force. The effects of the FSW process parameters on the ultimate tensile strength (UTS) of friction welded dissimilar joints were discussed. Optimization was carried out to maximize the UTS using response surface methodology (RSM) and the identified optimum FSW welding parameters were reported.

The hot deformation behaviors of Al-Zn-Mg-Sc-Zr alloy were investigated in a temperature range of 340–500 °C and a strain rate range of 0.001–10 s⁻¹ using uniaxial compression test on Gleeble-1500 thermal simulation machine. The results show that the flow stress increases with increasing strain and tends to be constant after a peak value. The flow stress increases with increasing strain rate and decreases with increasing deformation temperature. The phenomenon of dynamic recovery and dynamic recrystallization can be observed by microstructural evolutions. Based on the hyperbolic Arrhenius-type equation, the true stresstrue strain data from the tests were employed to establish the constitutive equation considering the effect of the true strain on material constants (α, β, Q, n and A), which reveals the dependence of the flow stress on strain, strain rate and deformation temperature. The predicted stress-strain curves are in good agreement with experimental results, which confirms that the developed constitutive equations are suitable to research the hot deformation behaviors of Al-Zn-Mg-Sc-Zr alloy.

ZnO-Bi₂O₃-based varistor ceramics doped with Eu₂O₃ in a range from 0 to 0.4% were obtained by high-energy ball milling and fired at 900–1 000 °C for 2 h. XRD and SEM were applied to determine the phases and microstructure of the varistor ceramics. A DC parameter instrument was applied to investigate the electronic properties and V-I characteristics. The XRD analysis of Eu₂O₃-doped ZnO-Bi₂O₃-based varistor ceramics shows that the ZnO, Eu-containing Bi-rich, Zn₇Sb₂O₁₂-type spinel and Zn₂Bi₃Sb₃O₁₄-type which is the pyrochlore phase are present. With increasing Eu₂O₃ content, the average size of ZnO grain firstly decreases and then increases. The grain boundary defect model was particularly used to explain the excellent nonlinearity of ZnO-Bi₂O₃-based varistor ceramics with the addition of 0.1 % Eu₂O₃ and sintered at 950 °C.

Maghemite-silica particulate nanocomposites were prepared by modified 2-step sol-gel process. Superparamagnetic maghemite nanoparticles were successfully produced using Massart’s procedure. Nanocomposites consisting of synthesized maghemite nanoparticles and silica were produced by dispersing the as-synthesized maghemite nanoparticles into the silica particulate form. The system was then heated at 140 °C for 3 d. A variety of mass ratios of Fe₂O₃/SiO₂ was investigated. Moreover, no surfactant or other unnecessary precursor was involved. The nanocomposites were characterized using XRD, BET and AGM. The XRD diffraction patterns show the reflection corresponding to maghemite nanoparticles and a visible wide band at 2θ from 20° to 35° which are the characteristics of the amorphous phase of the silica gel. The patterns also exhibit the presence of only maghemite and SiO₂ amorphous phase, which indicates that there is no chemical reaction between the silica particulate gel and maghemite nanoparticles to form other compounds. The calculated crystallite size for encapsulated maghemite nanoparticles is smaller than the as-synthesized maghemite nanoparticles indicating the dissolution of the nanoparticles. Very high surface area is attained for the produced nanocomposites (360–390 m²/g). This enhances the sensitivity and the reactivity of the nanocomposites. The shapes of the magnetization curves for nanocomposites are very similar to the as-synthesized maghemite nanoparticles. Superparamagnetic behaviour is exhibited by all samples, indicating that the size of the maghemite nanoparticles is always within the nanometre range. The increase in iron content gives rise to a small particle growth.

The fluid flow characteristics of the single bunch inclined jet impingement were investigated with different jet flow velocities, nozzle diameters, jet angles and jet-to-target distances for ultra-fast cooling technology. The results show that the peak pressure varying significantly from nearly 0.5 to above 13.4 kPa locates at the stagnation point with different jet diameters, and the radius of impact pressure affected zone is small promoted from 46 to 81 mm in transverse direction, and 50 to 91 mm in longitude direction when the jet flow velocity changes from 5 to 20 m/s. However, the fluid flow velocity is relatively smaller near the stagnation point, and increases gradually along the radius outwards, then declines. There is an obvious anisotropic characteristic that the flow velocity component along the jet direction is about twice of the contrary one where the jet anlge is 60°, jet diameter is 5 mm, jet length is 8 mm and jet height is 50 mm.

Double-layered pellet (DLP) roasting is a novel pretreatment method for sulfur and arsenic-bearing gold concentrates. In this process, preparation of DLPs is a fundamental step which is required to produce DLPs with favorable mechanical strength and thermal stability. Studies were carried out to investigate the affecting factors and conditions on the preparation and properties of DLPs. The results show that moisture content has significant influence on DLPs preparation. With the increase of moisture content in the range of no more than 9.8%, drop resistance and compressive strength of green DLPs are raised and the pelletizing dynamics is improved accordingly. The optimum conditions are determined as moisture content of 9.8%, coating time of 14–16 min, drying temperature <80 °C and drying gas velocity <1.2 m/s. When DLPs prepared under these conditions are roasted at 600 °C for 1 h, favorable removal and solidifying rates can be obtained, in which the removal rates of arsenic and sulfur are 94.38% and 82.55%, and the solidifying rates of arsenic and sulfur reach 99.62% and 99.79%, respectively. These results promise industrial application of DLP roasting.

Protein Rad23, a nucleotide excision repair factor, mainly involves in repairing the DNA damage from environment, such as UV light. The function of Rad23 protein involved in DNA damage repair from many environmental factors has been studied extensively, but it is not clear from ultraviolet irradiation. To further investigate the photo-protective function of Rad23 protein on HeLa cells damaged from UV light irradiation, firstly, HeLa cells were irradiated by UV light and incubated with the fusion protein of pCold-Rad23, then the cell viability and apoptosis rate were detected by MTT and Hoechst33342/PI fluorescent staining, respectively. The results show that the recombinant Rad23 protein can protect the HeLa cells from UV irradiation, and inhibit the apoptosis of HeLa cell by UV irradiation.

Two types of coaxial self-balancing robots (CSBR) were proposed, one can be used as a mobile robot platform for parts transporting in unmanned factory or as an inspector in dangerous areas, and the other can be used as a personal transporter ridden in cities. Mechanical designing and control structures as well as control strategies were described and compared in order to get a general way to develop such robots. A state feedback controller and a fuzzy controller were designed for the robot using DC servo motors and the robot using torque motors, respectively. The experiments indicate that the robots can realize various desired operations smoothly and agilely at the velocity of 0.6 m/s with an operator of 65 kg. Furthermore, the robustness of the controllers is revealed since these controllers can stabilize the robot even with unknown external disturbances.

In order to explore the precise dynamic response of the maglev train and verify the validity of proposed controller, a maglev guideway-electromagnet-air spring-cabin coupled model is developed in the first step. Based on the coupled model, the stresses of the modules are analyzed, and it is pointed out that the inherent nonlinearity, the inner coupling, misalignments between the sensors and actuators, and external disturbances are the main issues that should be considered for the maglev engineering. Furthermore, a feedback linearization controller based on the mathematical model of a maglev module is derived, in which the nonlinearity, coupling and misalignments are taken into account. Then, to attenuate the effect of external disturbances, a disturbance observer is proposed and the dynamics of the estimation error is analyzed using the input-to-state stability theory. It shows that the error is negligible under a low-frequency disturbance. However, at the high-frequency range, the error is unacceptable and the disturbances can not be compensated in time, which lead to over designed fluctuations of levitation gap, even a clash between the upper surface of electromagnet and lower surface of guideway. To solve this problem, a novel nonlinear acceleration feedback is put forward to enhancing the attenuation ability of fast varying disturbances. Finally, numerical comparisons show that the proposed controller outperforms the traditional feedback linearization controller and maintains good robustness under disturbances.

A method for improving the level of reliability of distribution systems is presented by employing an integrated voltage sag mitigation method that comprises a two-staged strategy, namely, distribution network reconfiguration (DNR) followed by DSTATCOM placement. Initially, an optimal DNR is applied to reduce the propagated voltage sags during the test period. The second stage involves optimal placement of the DSTATCOM to assist the already reconfigured network. The gravitational search algorithm is used in the process of optimal DNR and in placing DSTATCOM. Reliability assessment is performed using the well-known indices. The simulation results show that the proposed method is efficient and feasible for improving the level of system reliability.

The essential requirements of the end-effector of large space manipulator are capabilities of misalignment tolerance and soft capture. According to these requirements, an end-effector prototype combining the tendon-sheath transmission system with steel cable snaring mechanism was manufactured. An analysis method based on the coordinate transformation and the projection of key points of the mechanical interface was proposed, and it was a guideline of the end-effector design. Furthermore, the tendon-sheath transmission system was employed in the capture subassembly to reduce the inertia of the capture mechanism and enlarge the capture space. The capabilities of misalignment tolerance and soft capture were validated through the dynamic simulation in ADAMS software. The results of the capture simulation and experiment show that the end-effector has outstanding capabilities of misalignment tolerance and soft capture. The translation misalignments in radial directions are ±100 mm, and angular misalignments about pitch and yaw are ±15°.

LuGre model has been widely used in friction modeling and compensation. However, the new friction regime, named prestiction regime, cannot be accurately characterized by LuGre model in the latest research. With the extensive experimental observations of friction behaviors in the prestiction, some variables were abstracted to depict the rules in the prestiction regime. Based upon the knowledge of friction modeling, a novel friction model including the presliding regime, the gross sliding regime and the prestiction regime was then presented to overcome the shortcomings of the LuGre model. The reason that LuGre model cannot estimate the prestiction friction was analyzed in theory. Feasibility analysis of the proposed model in modeling the prestiction friction was also addressed. A parameter identification method for the proposed model based on multilevel coordinate search algorithm was presented. The proposed friction compensation strategy was composed of a nonlinear friction observer and a feedforward mechanism. The friction observer was designed to estimate the friction force in the presliding and the gross sliding regimes. And the friction force was estimated based on the model in the prestiction regime. The comparative trajectory tracking experiments were conducted on a simulator of inertially stabilization platforms among three control schemes: the single proportional-derivative (PD) control, the PD with LuGre model-based compensation and the PD with compensator based on the presented model. The experimental results reveal that the control scheme based on the proposed model has the best tracking performance. It reduces the peak-to-peak value (PPV) of tracking error to 0.2 mrad, which is improved almost 50% compared with the PD with LuGre model-based compensation. Compared to the single PD control, it reduces the PPV of error by 66.7%.

A simple control structure in servo system is occasionally needed for simple industrial application which precise and high control performance is not exessively important so that the cost production can be reduced efficiently. Simplified vector control, which has simple control structure, is utilized as the permanent magnet synchronous motor control algorithm and genetic algorithm is used to tune three PI controllers used in simplified vector control. The control performance is obtained from simulation and investigated to verify the feasibility of the algorithm to be applied in the real application. Simulation results show that the speed and torque responses of the system in both continuous time and discrete time can achieve good performances. Furthermore, simplified vector control combined with genetic algorithm has a similar performance with conventional field oriented control algorithm and possible to be realized into the real simple application in the future.

As the sampling rates of the inner loop and the outer loop of the target tracking control system are different, a typical digital multi-rate control system was formed. If the traditional single-rate design method was applied, the low sampling rate loop will seriously impact the dynamical characteristic of the system. After analyzing and calculating the impact law of the low sampling rate loop to the bandwidth and the stability of the tracking system, a kind of multi-rate control system design method was introduced. Corresponding to the different sampling rates of the inner loop and the outer loop, the multi-rate control strategy was constituted by a high sampling rate sub-controller and a low sampling rate sub-controller. The two sub-controllers were designed separately and connected by means of the sampling rate converter. The low sampling rate controller determined the response rapidity of the system, while the high sampling rate controller applied additionally effective control outputs to the system during a sampling interval of the low sampling rate controller. With the introduced high and low sampling rates sub-controllers, the tracking control system can achieve the same performance as a single-rate controller with high sampling rate, yet it works under a much lower sampling rate. The simulation and experimental results show the effectiveness of the introduced multi-rate control design method. It reduces the settling time by 5 times and the over shoot by 4 times compared with the PID control.

The joint optimization of detection threshold and waveform parameters for target tracking which comes from the idea of cognitive radar is investigated for the modified probabilistic data association (MPDA) filter. The transmitted waveforms and detection threshold are adaptively selected to enhance the tracking performance. The modified Riccati equation is adopted to predict the error covariance which is used as the criterion function, while the optimization problem is solved through the genetic algorithm (GA). The detection probability, false alarm probability and measurement noise covariance are all considered together, which significantly improves the tracking performance of the joint detection and tracking system. Simulation results show that the proposed adaptive waveform-detection threshold joint optimization method outperforms the adaptive threshold method and the fixed parameters method, which will reduce the tracking error. The average reduction of range error between the adaptive joint method and the fixed parameters method is about 0.6 m, while that between the adaptive joint method and the adaptive threshold only method is about 0.3 m. Similar error reduction occurs for the velocity error and acceleration error.

To solve the problem of sealing between the barrel and the rubber ring of shell body during an launching process of aerodynamic extinguishing cannon, a rubber sealing model with bionic dimpled characteristics was established based on the theory of bionic dimpled drag reduction and the principle of rubber sealing. In condition that the bionic dimpled characteristic diameters were 1, 2, 3, 4, and 5 mm, respectively, by numerical simulation, the influence of the installing compression of the rubber sealing ring on its surface stress and deformation was analyzed, and sealing performance of the rubber ring with different diameters of bionic dimpled was studied. The results show that the deformation of rubber ring appears prominent nonlinear characteristics when compression is increased from 1.5 mm to 2.5 mm. When the compression is 2.5 mm, the equivalent compression stress on the sealing areas of both sides of the rubber seal is greater than the working pressure of aerodynamic extinguishing cannon, which could meet the sealing requirement and would not cause leakage. So the rubber sealing ring with bionic dimpled surface possesses a good sealing characteristic and has no negative effect on the sealing of shell body; When the compression is 2.5 mm, the larger equivalent stress on the edge of sealing ring and the more even stress distribution in the high pressure area are generated due to the smaller compressive stress on the bionic dimple areas, which lays a foundation for the drag reduction characteristics of the shell body’s rubber ring with bionic dimpled surface.

Non-rigid point matching has received more and more attention. Recently, many works have been developed to discover global relationships in the point set which is treated as an instance of a joint distribution. However, the local relationship among neighboring points is more effective under non-rigid transformations. Thus, a new algorithm taking advantage of shape context and relaxation labeling technique, called SC-RL, is proposed for non-rigid point matching. It is a strategy that joints estimation for correspondences as well as the transformation. In this work, correspondence assignment is treated as a soft-assign process in which the matching probability is updated by relaxation labeling technique with a newly defined compatibility coefficient. The compatibility coefficient is one or zero depending on whether neighboring points preserving their relative position in a local coordinate system. The comparative analysis has been performed against four state-of-the-art algorithms including SC, ICP, TPS-RPM and RPM-LNS, and the results denote that SC-RL performs better in the presence of deformations, outliers and noise.

Gaussian process (GP) has fewer parameters, simple model and output of probabilistic sense, when compared with the methods such as support vector machines. Selection of the hyper-parameters is critical to the performance of Gaussian process model. However, the common-used algorithm has the disadvantages of difficult determination of iteration steps, over-dependence of optimization effect on initial values, and easily falling into local optimum. To solve this problem, a method combining the Gaussian process with memetic algorithm was proposed. Based on this method, memetic algorithm was used to search the optimal hyper parameters of Gaussian process regression (GPR) model in the training process and form MA-GPR algorithms, and then the model was used to predict and test the results. When used in the marine long-range precision strike system (LPSS) battle effectiveness evaluation, the proposed MA-GPR model significantly improved the prediction accuracy, compared with the conjugate gradient method and the genetic algorithm optimization process.

In order to study the variation of machine tools’ dynamic characteristics in the manufacturing space, a Kriging approximate model is proposed. Finite element method (FEM) is employed on the platform of ANSYS to establish finite element (FE) model with the dynamic characteristic of combined interface for a milling machine, which is newly designed for producing aero engine blades by a certain enterprise group in China. The stiffness and damping of combined interfaces are adjusted by using adaptive simulated annealing algorithm with the optimizing software of iSIGHT in the process of FE model update according to experimental modal analysis (EMA) results. The Kriging approximate model is established according to the finite element analysis results utilizing orthogonal design samples by taking into account of the range of configuration parameters. On the basis of the Kriging approximate model, the response surfaces between key response parameter and configuration parameters are obtained. The results indicate that configuration parameters have great effects on dynamic characteristics of machine tools, and the Kriging approximate model is an effective and rapid method for estimating dynamic characteristics of machine tools in the manufacturing space.

Single-axis rotation technique is often used in the marine laser inertial navigation system so as to modulate the constant biases of non-axial gyroscopes and accelerometers to attain better navigation performance. However, two significant accelerometer nonlinear errors need to be attacked to improve the modulation effect. Firstly, the asymmetry scale factor inaccuracy enlarges the errors of frequent zero-cross oscillating specific force measured by non-axial accelerometers. Secondly, the traditional linear model of accelerometers can hardly measure the continued or intermittent acceleration accurately. These two nonlinear errors degrade the high-precision specific force measurement and the calibration of nonlinear coefficients because triaxial accelerometers is urgent for the marine navigation. Based on the digital signal sampling property, the square coefficients and cross-coupling coefficients of accelerometers are considered. Meanwhile, the asymmetry scale factors are considered in the I-F conversion unit. Thus, a nonlinear model of specific force measurement is established compared to the linear model. Based on the three-axis turntable, the triaxial gyroscopes are utilized to measure the specific force observation for triaxial accelerometers. Considering the nonlinear combination, the standard calibration parameters and asymmetry factors are separately estimated by a two-step iterative identification procedure. Besides, an efficient specific force calculation model is approximately derived to reduce the real-time computation cost. Simulation results illustrate the sufficient estimation accuracy of nonlinear coefficients. The experiments demonstrate that the nonlinear model shows much higher accuracy than the linear model in both the gravimetry and sway navigation validations.

Compared to the rank reduction estimator (RARE) based on second-order statistics (called SOS-RARE), the RARE employing fourth-order cumulants (referred to as FOC-RARE) is capable of dealing with more sources and mitigating the negative influences of the Gaussian colored noise. However, in the presence of unexpected modeling errors, the resolution behavior of the FOC-RARE also deteriorate significantly as SOS-RARE, even for a known array covariance matrix. For this reason, the angle resolution capability of the FOC-RARE was theoretically analyzed. Firstly, the explicit formula for the mathematical expectation of the FOC-RARE spatial spectrum was derived through the second-order perturbation analysis method. Then, with the assumption that the unexpected modeling errors were drawn from complex circular Gaussian distribution, the theoretical formulas for the angle resolution probability of the FOC-RARE were presented. Numerical experiments validate our analytical results and demonstrate that the FOC-RARE has higher robustness to the unexpected modeling errors than that of the SOS-RARE from the resolution point of view.

Practical techniques for smooth geodesic patterning of membrane structures were investigated. For the geodesic search, adjustment of the subplane of the extracted elements series was proposed, and various spline approximation methods were used to flatten the strip for the generation of a smooth pattern. This search approach is very simple, and the geodesic line could be easily attained by the proposed method without the need for a difficult computation method. Smooth cutting patterning can also be generated by spline approximation without the noise in discrete nodal information. Additionally, the geodesic cutting pattern saved about 21% of the required area for the catenary model due to the reduction of the curvature of the planar pattern seam line.

In recent years, using message ferries as mechanical carriers of data has been shown to be an effective way to collect information in sparse wireless sensor networks. As the sensors are far away from each other in such highly partitioned scenario, a message ferry needs to travel a long route to access all the sensors and carry the data collected from the sensors to the sink. Typically, practical constraints (e.g., the energy) preclude a ferry from visiting all sensors in a single tour. In such case, the ferry can only access part of the sensors in each tour and move back to the sink to get the energy refilled. So, the energy-constrained ferry route design (ECFRD) problem is discussed, which leads to the optimization problem of minimizing the total route length of the ferry, while keeping the route length of each tour below a given constraint. The ECFRD problem is proved to be NP-hard problem, and the integer linear programming (ILP) formulation is given. After that, efficient heuristic algorithms are proposed to solve this problem. The experimental results show that the performances of the proposed algorithms are effective in practice compared to the optimal solution.

Based on the observation that there exists multiple information in a pixel neighbor, such as distance sum and gray difference sum, local information enhanced LBP (local binary pattern) approach, i.e. LE-LBP, is presented. Geometric information of the pixel neighborhood is used to compute minimum distance sum. Gray variation information is used to compute gray difference sum. Then, both the minimum distance sum and the gray difference sum are used to build a feature space. Feature spectrum of the image is computed on the feature space. Histogram computed from the feature spectrum is used to characterize the image. Compared with LBP, rotation invariant LBP, uniform LBP and LBP with local contrast, it is found that the feature spectrum image from LE-LBP contains more details, however, the feature vector is more discriminative. The retrieval precision of the system using LE-LBP is 91.8% when recall is 10% for bus images.

A new parallel architecture for quantified boolean formula (QBF) solving was proposed, and the prediction model based on machine learning technology was proposed for how sharing knowledge affects the solving performance in QBF parallel solving system, and the experimental evaluation scheme was also designed. It shows that the characterization factor of clause and cube influence the solving performance markedly in our experiment. At the same time, the heuristic machine learning algorithm was applied, support vector machine was chosen to predict the performance of QBF parallel solving system based on clause sharing and cube sharing. The relative error of accuracy for prediction can be controlled in a reasonable range of 20%–30%. The results show the important and complex role that knowledge sharing plays in any modern parallel solver. It shows that the parallel solver with machine learning reduces the quantity of knowledge sharing about 30% and saving computational resource but does not reduce the performance of solving system.

High intensity focused ultrasound (HIFU) therapy is an effective method in clinical treatment of tumors, in order to explore the bio-heat conduction mechanism of in multi-layer media by concave spherical transducer, temperature field induced by this kind of transducer in multi-layer media will be simulated through solving Pennes equation with finite difference method, and the influence of initial sound pressure, absorption coefficient, and thickness of different layers of biological tissue as well as thermal conductivity parameter on sound focus and temperature distribution will be analyzed, respectively. The results show that the temperature in focus area increases faster while the initial sound pressure and thermal conductivity increase. The absorption coefficient is smaller, the ultrasound intensity in the focus area is bigger, and the size of the focus area is increasing. When the thicknesses of different layers of tissue change, the focus position changes slightly, but the sound intensity of the focus area will change obviously. The temperature in focus area will rise quickly before reaching a threshold, and then the temperature will keep in the threshold range.

A new human action recognition approach was presented based on chaotic invariants and relevance vector machines (RVM). The trajectories of reference joints estimated by skeleton graph matching were adopted for representing the nonlinear dynamical system of human action. The C-C method was used for estimating delay time and embedding dimension of a phase space which was reconstructed by each trajectory. Then, some chaotic invariants representing action can be captured in the reconstructed phase space. Finally, RVM was used to recognize action. Experiments were performed on the KTH, Weizmann and Ballet human action datasets to test and evaluate the proposed method. The experiment results show that the average recognition accuracy is over 91.2%, which validates its effectiveness.

A novel regularization-based approach is presented for super-resolution reconstruction in order to achieve good tradeoff between noise removal and edge preservation. The method is developed by using L1 norm as data fidelity term and anisotropic fourth-order diffusion model as a regularization item to constrain the smoothness of the reconstructed images. To evaluate and prove the performance of the proposed method, series of experiments and comparisons with some existing methods including bi-cubic interpolation method and bilateral total variation method are carried out. Numerical results on synthetic data show that the PSNR improvement of the proposed method is approximately 1.0906 dB on average compared to bilateral total variation method, and the results on real videos indicate that the proposed algorithm is also effective in terms of removing visual artifacts and preserving edges in restored images.

Due to the nature of ultra-short-acting opioid remifentanil of high time-varying, complex compartment model and low-accuracy of plasma concentration prediction, the traditional estimation method of population pharmacokinetics parameters, nonlinear mixed effects model (NONMEM), has the abuses of tedious work and plenty of man-made jamming factors. The Elman feedback neural network was built. The relationships between the patients’ plasma concentration of remifentanil and time, patient’ age, gender, lean body mass, height, body surface area, sampling time, total dose, and injection rate through network training were obtained to predict the plasma concentration of remifentanil, and after that, it was compared with the results of NONMEM algorithm. In conclusion, the average error of Elman network is −6.34%, while that of NONMEM is 18.99%. The absolute average error of Elman network is 27.07%, while that of NONMEM is 38.09%. The experimental results indicate that Elman neural network could predict the plasma concentration of remifentanil rapidly and stably, with high accuracy and low error. For the characteristics of simple principle and fast computing speed, this method is suitable to data analysis of short-acting anesthesia drug population pharmacokinetic and pharmacodynamics.

Nowadays, a certain amount of landfills in China were constructed without horizontal liner system. The research conducted focuses mainly on the contaminants from landfill leachate migrating in the aquifer of a fractured granite area, and pollution predictions for groundwater were made by establishing numerical model with Visual Modflow combining field investigation like geological surveys, drilling, geophysical explorations, hydrogeological experiments, water quality analysis. The transportation of the chloride ion from landfill in the aquifer was simulated in the model with time frames of 2 555, 3 650, 5 475 and 7 300 d. The model shows that from 2 555 d to 7 300 d starting from 2003, the chloride ion migrated from 900 m to 1 300 m, respectively, along the groundwater flow. The results indicate that as leachate plume migrated in the aquifer, the concentration of the pollutants can be up to 19.74 to 251.76 times that of background value. The research proves that the leachate poses a threat to the local water body and offers a reference towards groundwater pollution prevention for fractured granite landfill sites.

The 2-dimensional unsteady aerodynamic forces, in the context of both a thin airfoil where theory of potential flow is always applicable and a bluff bridge-deck section where separated flow is typically induced, are investigated from a point of view of whether or not they conform to the principle of linear superposition in situations of various structural motions and wind gusts. It is shown that some basic preconditions that lead to the linear superposability of the unsteady aerodynamic forces in cases of thin airfoil sections are no longer valid for a bluff section. Theoretical models of bridge aerodynamics such as the one related to flutter-buffeting analysis and those concerning aerodynamic admittance (AA) functions, however, necessitate implicitly this superposability. The contradiction revealed in this work may throw light on the perplexing problem of AA functions pertaining to the description of buffeting loads of bridge decks. Some existing theoretical AA models derived from flutter derivatives according to interrelations valid only for thin airfoil theories, which have been employed rather extensively in bridge aerodynamics, are demonstrated to be illogical. Finally, with full understanding of the preconditions of the applicability of linear superposability of the unsteady aerodynamic forces, suggestions in regard to experiment-based AA functions are presented.

Traditional gust load factor (GLF) method, inertial wind load (IWL) method and tri-component method (LRC+IWL) cannot accurately analyze the wind-induced responses of super-large cooling towers, so the real combination formulas of fluctuating wind-induced responses and equivalent static wind loads (ESWLSs) were derived based on structural dynamics and random vibration theory. The consistent coupled method (CCM) was presented to compensate the coupled term between background and resonant response. Taking the super-large cooling tower (H=215 m) of nuclear power plant in Jiangxi Province, China, which is the highest and largest in China, as the example, based on modified equivalent beam-net design method, the aero-elastic model for simultaneous pressure and vibration measurement of super-large cooling tower is firstly carried out. Then, combining wind tunnel test and CCM, the effects of self-excited force on the surface pressures and wind-induced responses are discussed, and the wind-induced response characteristics of background component, resonant component, coupled term between background and resonant response, fluctuating responses, and wind vibration coefficients are discussed. It can be concluded that wind-induced response mechanism must be understood to direct the wind resistant design for super-large cooling towers.

Recently, the radial point interpolation meshfree method has gained popularity owing to its advantages in large deformation and discontinuity problems, however, the accuracy of this method depends on many factors and their influences are not fully investigated yet. In this work, three main factors, i.e., the shape parameters, the influence domain size, and the nodal distribution, on the accuracy of the radial point interpolation method (RPIM) are systematically studied and conclusive results are obtained. First, the effect of shape parameters (R, q) of the multi-quadric basis function on the accuracy of RPIM is examined via global search. A new interpolation error index, closely related to the accuracy of RPIM, is proposed. The distribution of various error indexes on the R-q plane shows that shape parameters q ∈ [1.2, 1.8] and R ∈ [0, 1.5] can give good results for general 3-D analysis. This recommended range of shape parameters is examined by multiple benchmark examples in 3D solid mechanics. Second, through numerical experiments, an average of 30–40 nodes in the influence domain of a Gauss point is recommended for 3-D solid mechanics. Third, it is observed that the distribution of nodes has significant effect on the accuracy of RPIM although it has little effect on the accuracy of interpolation. Nodal distributions with better uniformity give better results. Furthermore, how the influence domain size and nodal distribution affect the selection of shape parameters and how the nodal distribution affects the choice of influence domain size are also discussed.

According to the characteristics of thin-layer rolling and pouring construction technology and the complicated mechanical behavior of the roller compacted concrete dam (RCCD) construction interface, a constitutive model of endochronic damage was established based on the endochronic theory and damage mechanics. The proposed model abandons the traditional concept of elastic-plastic yield surface and can better reflect the real behavior of rolled control concrete. Basic equations were proposed for the fluid-solid coupling analysis, and the relationships among the corresponding key physical parameters were also put forward. One three-dimensional finite element method (FEM) program was obtained by studying the FEM type of the seepage-stress coupling intersection of the RCCD. The method was applied to an actual project, and the results show that the fluid-solid interaction influences dam deformation and dam abutment stability, which is in accordance with practice. Therefore, this model provides a new method for revealing the mechanical behavior of RCCD under the coupling field.

A simplified probabilistic analysis of geomembrane punctures from granular material was presented when subjected to liquid pressure. The probability distribution of contact force between geomembrane and granular material was obtained based on the principle of equal probability and assumptions that grains are spheres with constant size. A particle flow code PFC^3D was employed to simulate the contact process which indicates a good agreement with the theoretical probabilistic analysis. The odds of geomembrane puncture from grains of constant size were obtained by evaluating the puncture force which should not exceed the puncture resistance of geomembrane. The effects of grain radius, grain rigidity and liquid pressure were studied in more detail and displayed in graphs. Both high-level of liquid pressure and large grain can result in high risk of geomembrane puncture. The influence of grain rigidity on the geomembrane puncture odds is significant. For granular material with a grain size distribution, the geomembrane puncture odds can be estimated by the grain size distribution, served as weight function and it is a cautious design if the largest grain is chosen as the design grain size.

A new hybrid optimization algorithm was presented by integrating the gravitational search algorithm (GSA) with the sequential quadratic programming (SQP), namely GSA-SQP, for solving global optimization problems and minimization of factor of safety in slope stability analysis. The new algorithm combines the global exploration ability of the GSA to converge rapidly to a near optimum solution. In addition, it uses the accurate local exploitation ability of the SQP to accelerate the search process and find an accurate solution. A set of five well-known benchmark optimization problems was used to validate the performance of the GSA-SQP as a global optimization algorithm and facilitate comparison with the classical GSA. In addition, the effectiveness of the proposed method for slope stability analysis was investigated using three case studies of slope stability problems from the literature. The factor of safety of earth slopes was evaluated using the Morgenstern-Price method. The numerical experiments demonstrate that the hybrid algorithm converges faster to a significantly more accurate final solution for a variety of benchmark test functions and slope stability problems.

Long time monitoring is acquired to obtain the displacement data for displacement-based geotechnical material back analysis, and these data are hard to be measured under some special condition, such as earthquake. For a simple homogeneous slope, the position of a critical failure surface is determined by value of c/tan ϕ. Utilizing upper bound theorem of limit analysis, the external work rate and internal energy for normal slope under earthquake forces are given, and the formula for minimum safety factor is derived. On this basis, the equation of slip surface and the surface depth of a given position are solved. In this way, the strength parameter can be analyzed by known slip surface depth. For practical use, the surface depth for a given slope under varying strength parameter is presented. Finally, two examples are given to show its simplicity and effectiveness.

To assess the effectiveness of vacuum preloading combined electroosmotic strengthening of ultra-soft soil and study the mechanism of the process, a comprehensive experimental investigation was performed. A laboratory test cell was designed and applied to evaluate the vacuum preloading combined electroosmosis. Several factors were taken into consideration, including the directions of the electroosmotic current and water induced by vacuum preloading and the replenishment of groundwater from the surrounding area. The results indicate that electroosmosis together with vacuum preloading improve the soil strength greatly, with an increase of approximately 60%, and reduce the water content of the soil on the basis of consolidation of vacuum preloading, however, further settlement is not obvious with only 1.7 mm. The reinforcement effect of vacuum preloading combined electroosmosis is better than that of electroosmosis after vacuum preloading. Elemental analysis using X-ray fluorescence proves that the soil strengthening during electroosmotic period in this work is mainly caused by electroosmosis-induced electrochemical reactions, the concentrations of Al₂O₃ in the VPCEO region increase by 2.2%, 1.5%, and 0.9% at the anode, the midpoint between the electrodes, and the cathode, respectively.

Based on Biot’s theory and considering the properties of a cavity, the boundary integral equations for the numerical simulation of wave scattering around a cavity with a circular cross-section embedded in saturated soil are obtained using integral transform methods. The Cauchy type singularity of the boundary integral equation is discussed. The effectiveness of the properties of soil mass and incident field on the dynamic stress concentration and pore pressure concentration around a cavity is analyzed. Our results are in good agreement with the existing solution. The numerical results of this work show that the dynamic stress concentration and pore pressure concentration are influenced by the degree of fluid-solid coupling as well as the pore compressibility and water permeability of saturated soil. With increased degree of fluid-solid coupling, the dynamic stress concentration improves from 1.87 to 3.42 and the scattering becomes more significant. With decreased index of soil mass compressibility, the dynamic stress concentration increases and its maximum reaches 3.67. The dynamic stress concentration increases from 1.64 to 3.49 and pore pressure concentration improves from 0.18 to 0.46 with decreased water permeability of saturated soil.

Isotropic consolidation test and consolidated-undrained triaxial test were first undertaken to obtain the parameters of the modified cam-clay (MCC) model and the behavior of natural clayey soil. Then, for the first time, numerical simulation of the two tests was performed by three-dimensional finite element method (FEM) using ABAQUS program. The consolidated-drained triaxial test was also simulated by FEM and compared with theoretical results of MCC model. Especially, the behaviors of MCC model during unloading and reloading were analyzed in detail by FEM. The analysis and comparison indicate that the MCC model is able to accurately describe many features of the mechanical behavior of the soil in isotropic consolidation test and consolidated-drained triaxial test. And the MCC model can well describe the variation of excess pore water pressure with the development of axial strain in consolidated-undrained triaxial test, but its ability to predict the relationship between axial strain and shear stress is relatively poor. The comparison also shows that FEM solutions of the MCC model are basically identical to the theoretical ones. In addition, Mandel-Cryer effect unable to be discovered by the conventional triaxial test in laboratories was disclosed by FEM. The analysis of unloading-reloading by FEM demonstrates that the MCC model disobeys the law of energy conservation under the cyclic loading condition if the elastic shear modulus is linearly pressure-dependent.

X-style arch bridge on high-speed railways (HSR) is one kind of complicated long-span structure, and the track-bridge interaction is essential to ensure the safety and smoothness of HSR. Taking an X-style steel-box arch bridge with a main span of 450 m on HSR under construction for example, a new integrative mechanic model of rail-stringer-cross beam-suspender-pier-foundation coupling system was established, adopting the nonlinear spring element simulating the longitudinal resistance between track and bridge. The transmission law of continuous welded rail (CWR) on the X-style arch bridge was researched, and comparative study was carried out to discuss the influence of several sensitive factors, such as the temperature load case, the longitudinal resistance model, the scheme of longitudinal restraint conditions, the introverted inclination of arch rib, the stiffness of pier and abutment and the location of the rail expansion device. Calculating results indicate that the longitudinal resistance has a significant impact upon the longitudinal forces of CWR on this kind of bridge, while the arch rib’s inclination has little effect. Besides, temperature variation of arch ribs and suspenders should be taken into account in the calculation. Selecting the restraint system without longitudinally-fixed bearing and setting the rail expansion devices on both ends are more reasonable.

The decision-making and optimization of two-echelon inventory coordination were analyzed with service level constraint and controllable lead time sensitive to order quantity. First, the basic model of this problem was established and based on relevant analysis, the original model could be transformed by minimax method. Then, the optimal order quantity and production quantity influenced by service level constraint were analyzed and the boundary of optimal order quantity and production quantity was given. According to this boundary, the effective method and tactics were put forward to solve the transformed model. In case analysis, the optimal expected total cost of two-echelon inventory can be obtained and it was analyzed how service level constraint and safety factor influence the optimal expected total cost of two-echelon inventory. The results show that the optimal expected total cost of two-echelon inventory is constrained by the higher constraint between service level constraint and safety factor.

A critical safe distance (CSD) model in V2V (vehicle-to-vehicle) communication systems was proposed to primarily enhance driving safety by disseminating warning notifications to vehicles when they approach calculated CSD. By elaborately analyzing the vehicular movement features especially when braking, our CSD definition was introduced and its configuration method was given through dividing radio range into different communication zones. Based on our definition, the needed message propagation delay was also derived which could be used to control the beacon frequency or duration. Next, the detailed CSD expressions were proposed in different mobility scenarios by fully considering the relative movement status between the front and rear vehicles. Numerical results show that our proposed model could provide reasonable CSD under different movement scenarios which eliminates the unnecessary reserved inter-vehicle distance and guarantee the safety at the same time. The compared time-headway model always shows a smaller CSD due to focusing on traffic efficiency whereas the traditional braking model generally outputs a larger CSD because it assumes that the following car drives with a constant speed and did not discuss the scenario when the leading car suddenly stops. Different from these two models, our proposed model could well balances the requirements between driving safety and traffic throughput efficiency by generating a CSD in between the values of the two models in most cases.