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Studying the flow of the rice particle helps to improve the efficiency of rice processing and reduce energy losses during sorting and transportation. A change in the aspect ratio of rice grains leads to the fact that the layer of particles has a complex surface morphology. As a result, the velocity distribution of rice particles differs from the velocity distribution of classical spherical particles. Experiments show that rice particles flow often has distribution with multiple velocity peaks. When the drum rotation speed is reduced to 1–3 rpm, the flow of rice particles turns into an avalanche mode. It has been found that the avalanche mechanism is the slope of the accumulation surface exceeds the angle of repose, causing the particles to slide and cover the entire rice particle bed.

Frequent earthquakes have brought enormous life and property losses to Taiwan Island, and thus reliable earthquake forecasts are valuable. We form 20 tectonics-based shallow earthquake forecasts of Taiwan Island for the years 2019 and after, each with a different threshold moment magnitude, ranging from 5.45 in steps of 0.05 up to 6.40. Our results suggest that Taiwan Island may experience about 25 Mw ≥ 6.25, 40 Mw ≥ 6.00, 65 Mw ≥ 5.75 and 106 Mw ≥ 5.50 shallow earthquakes every 100 years. We demonstrate the consistency between the forecast results and the seismic catalog used for the forecasts and carry out retrospective tests against the seismic catalogs of Taiwan Island not used in the forecasts, which show higher forecast success relative to previous studies of global earthquake forecasts. We identify three gaps of Mw ≥ 6.40 shallow earthquakes, located in Yilan County, Hualien County and Taitung County. We find a general negative correlation between our Mw ≥ 6.40 shallow earthquake forecast and the population density distribution in Taiwan Island. However, we emphasize that the regions with relatively low forecast values need special attention, because these regions generally have relatively high population densities but may also experience strong earthquakes.

Collapses of braced or tied-back excavations have occurred frequently. However, the influence of the failure of some retaining structure members on the overall safety performance of a retaining system has not been studied. Model tests of failures of retaining piles, struts or anchors were conducted in this study and the load-transfer mechanisms underlying these conditions were analysed. When failures or large deformations occurred in certain piles, the increasing ratios of the bending moments in adjacent piles were much larger in the braced retaining system than in the cantilever system and more easily triggered progressive failure. When the strut elevation was lower or the excavation depth was greater, the degree of influence and range of pile failures became larger. When certain struts or anchors failed, their loads transferred to a few adjacent struts or anchors, possibly leading to further strut or anchor failure. The influence mechanisms of strut or anchor failure on piles were different from those of pile failure. As the number of failed struts or anchors increases, the bending moments of the piles in the failure zone first decrease and then increase to very high values. Therefore, the progressive failure path extends from struts or anchors to piles and will lead to large-scale collapse.

Tunnels buried in liquefiable deposits are vulnerable to liquefaction-induced uplift damage during earthquakes. This paper presents support vector machine (SVM) and artificial neural network (ANN) models to predict the liquefaction-induced uplift displacement of tunnels based on artificial databases generated by the finite difference method. The performance of the SVM and ANN models was assessed using statistical parameters, including the coefficient of determination R2, the mean absolute error, and the root mean squared error. Applications for the above-mentioned approaches are compared and discussed. A relative importance analysis was adopted to quantify the sensitivity of each input variable. The precision of the presented models is demonstrated using centrifuge test results from previous studies.

In this study, the optical flow method is used to measure the velocity distribution of a granular flow in a rectangular quasi-two-dimensional silo. Using the velocity gradient, a free-fall arch (FFA) is obtained and its geometric characteristics are calculated. A parabola-shaped FFA structure is discovered above the orifice in the steady flow state. The shape of the FFA affects the flow rate through the orifice. Furthermore, as jamming begins to occur, the geometry of the FFA disappears gradually from both sides and then from the middle; finally, the FFA disappears completely in the state of jamming. As the boundary between finite-stress and stress-free regions, the FFA facilitates further studies regarding the discontinuity of the stress area above the orifice.

Frequency-modulated continuous-wave (FMCW) interference, as a new technology of laser interferometry, has the advantages of length traceability, large range, high accuracy, simple structure, and optical fiber transmission. Based on the formula of FMCW laser interference displacement, a zero-crossing phase detection algorithm is proposed, which can accurately calculate the initial phase of a cosine signal in a modulation period, and it is successfully applied to the contact laser interference displacement sensor. The experimental results show that the FMCW technology based on the zero-crossing phase detection algorithm can achieve the technical specifications of the contact displacement sensor with a measurement range greater than 15 mm and the standard deviation is less than 0.01 μm. The conversion of noncontact measurement to contact measurement can realize the direct measurement of workpieces with complex surface conditions on the production line, breaking through the limitation of optical measurement and expanding the application of optical fiber interferometry.

Incompressible dipping substrata are commonly encountered in engineering practice. Compared to horizontal underlying strata, the inclined underlying stratum increase the risk of collapse of embankments reinforced with columns because it weakens the restraint of the column base. The objective of this study is to investigate the effectiveness of geosynthetics on improving the embankment stability when the underlying stratum is inclined. The influence of geosynthetic tensile stiffness on the ultimate surcharge and failure mechanism is studied. A deep-seated failure with column tilting occurs when the geosynthetic tensile stiffness is low, whereas a lateral sliding occurs when the geosynthetic tensile stiffness is high. To illustrate the contribution of geosynthetics, the distribution of the lateral pressures acting on the columns is analyzed.

The 0.2% strain offset approach is mostly used to calculate the yield stress and serves as an efficient method for cross-lab comparisons of measured material properties. However, it is difficult to accurately determine the yield of the bone. Especially when computational models require accurate material parameters, clarification of the yield point is needed. We tested 24 cortical specimens harvested from six bovine femora in three-point bending mode, and 11 bovine femoral cortical specimens in the tensile mode. The Young's modulus and yield stress for each specimen derived from the specimen-specific finite element (FE) optimization method was regarded as the most ideal constitutive parameter. Then, the strain offset optimization method was used to find the strain offset closest to the ideal yield stress for the 24 specimens. The results showed that the 0 strain offsets underestimated (- 25%) the yield stress in bending and tensile tests, while the 0.2% strain offsets overestimated the yield stress (+ 65%) in three-point bending tests. Instead, the yield stress determined by 0.007 and 0.05% strain offset for bending and tensile loading respectively, can effectively characterize the biomechanical responses of the bone, thereby helping to build an accurate FE model.

An efficient numerical method for the wideband scattering analysis of the freestanding large-scale finite periodic array is presented using the macro block-characteristic basis function method (MB-CBFM) and the improved frequency-independent reaction (FIR). In the MB-CBFM, the blocks (unit cells) are divided into some types of macro blocks. By analyzing the subarray with the macro blocks, the CBFs for the macro blocks will be obtained. The blocks in the same macro block share the same CBFs. Substituting the CBFs into the moment matrix equation, a reduced matrix equation whose size does not depend on the number of the blocks can be obtained and handled utilizing direct methods. When the MB-CBFM is applied for wideband analysis, the matrix needs to be recomputed. The reduced matrix can be efficiently generated by using the improved FIR, in which the matrix elements are expressed as the product of the geometrical elements and the phase factor. The geometrical elements are computed one time and reused. Only the phase factor needs to be recomputed. Several numerical examples are carried out. Simulation results show that the results of the proposed algorithm agree well with those of other numerical methods. The total CPU time is significantly reduced.

Wind farms (WFs) are important components of smart grid. The modeling and optimal planning of the WF is preliminary before its construction. In this article, a bi-level multi-objective optimization framework is presented, with the aim of simultaneously designing the configuration of wind turbines (WTs) as well as the topology of electrical collector system in an offshore WF. The installation capacity of the WF, the positioning of the WTs and the planning scheme of the electrical system are balanced to achieve a better performance of the WF. In this proposal, there is an outer layer along with two inner layers. The objectives of the outer-layer model are the maximization of the WF’s daily profit rate, the daily average capacity factor, and power quality. It is tackled by the Non-dominated Sorting Genetic Algorithm-III (NSGA-III). The objectives of the two inner layer models are to determine the topology of the electrical system and the generation schedule of other generators, and are solved by means of the Binary Particle Swarm Optimization (BPSO) algorithm and the quadratic programming (QP) method respectively. The WF is assumed to be connected to the IEEE-24 bus test system. The simulation results validate the adaptability and effectiveness of the proposed approach with the main factors that affect the WF layout being analyzed.

A large volume of groundwater is withdrawn annually in Tianjin Municipality, China, to meet agricultural, industrial, and municipal water uses. Groundwater overdraft in the urban districts and the Binhai New District in Tianjin Municipality has caused land subsidence. A series of field observation wells were installed to monitor the long-term groundwater level (GWL). The hydrostratigraphy of the aquifer system underlying Tianjin consists of four aquifer layers. The middle two aquifer layers are the main layers for groundwater withdrawal. The GWL of the top two aquifer layers responded rapidly to recharge from precipitation and seawater intrusion. The GWLs of the bottom two aquifer layers have been dropping steadily over the past 50 years. The aquifer sediments underlying Tianjin Municipality consist mainly of fine sand, silt, and clayey soil. The decline of the GWL has induced substantial land subsidence and led to overconsolidated compressible sediments.

An accurate wake model is essential for the mathematical modeling of a wind farm (WF) and the optimal positioning of wind turbines (WTs). In order to effectively solve the WF layout optimization problem, this paper presents a newly-developed three-dimensional (3D) Gaussian wake model and applies it to the optimization of a WF layout. Firstly, the basic functions of the proposed model are deduced. Secondly, it is validated by wind tunnel measured data, and compared with the one-dimensional (1D) and the two-dimensional (2D) wake models. Then, the 3D Gaussian wake model is applied in the WF layout optimization problems with identical and multiple types of WTs. The optimization objective is to maximize the total output power of the WF with a set of constraints. The Mixed-Discrete Particle Swarm Optimization (MDPSO) algorithm is used to solve the uniform and nonuniform WF layout optimization problems. Test cases of various WF sizes, wind conditions, and different wake models are simulated and analyzed. The simulation results demonstrate that the 3D Gaussian wake model can effectively address the WF layout optimization problem and further illustrate that the nonuniform design is beneficial to increase the WF’s output power.

This study was evaluating how three desensitizing toothpastes used at home influence the effect associated with desensitizing agents after application in the clinic. Fifty dentine disks measure it permeability and 32 dentine disks with similar permeability levels were selected. Following Dental desensitizer treatment, dentine disks were randomly divided into three subgroups (n=10) that received applications of three toothpastes, respectively. The permeability (Lp) of each specimen was measured after each treatment. One specimen was selected from each group for scanning electron microscopy (SEM) observation. After each treatment, the Lp values decreased significantly for each group (p 0.05). After using the Dental desensitizer, Sensodyne, Crest and Colgate desensitizing toothpastes both can continued to reduce the permeability of the dentine disk, and no significant differences were found amongst them.

The hydrogeologic conditions in Tianjin, China, are characterized by a system of multiple alternating aquifers and aquitards and a high groundwater level. Generally, the groundwater system to a depth of 70 m includes one phreatic aquifer and three semiconfined aquifers (AqI–AqIII). The distribution of aquifers varies greatly. Accurate estimates of aquifer parameters from pumping tests are essential in geotechnical engineering practice. In this study, the applicability of different models for estimating hydraulic parameters in a multiaquifer system is analyzed. To avoid errors in the graphic-analytical process and to enhance the efficiency and accuracy, a hybrid algorithm, called GALMA (a genetic algorithm (GA) combined with the Levenberg–Marquardt (LM) algorithm), is used with the Neuman and Witherspoon model and ratio method. The estimated values in the second and third semiconfined aquifers (AqII and AqIII) from various solutions are compared with the measured data. Further validations based on the prediction of the drawdown values are performed via a three dimensional numerical simulation.

In order to improve the dynamic performance and stability of general acceleration slip regulation (ASR) control technology for four-wheel independent drive electric vehicle (4WID EV), an ASR control strategy based on variable gain controller (VGC) is proposed in this paper. First of all, a road identification strategy is designed to identify the current road surface and calculate the optimal slip ratio of the road. Then, the optimal slip ratio is taken as the control target, and the ASR control strategy based on VGC is designed to keeps slip ratio around the optimum slip ratio through controlling the driving torque output, so wheels can make the best of road adhesion to prevent vehicle from slipping. Meanwhile, we analyze the control system state space, and build a scalar function of the system, and prove that the system satisfies Lyapunov large scale asymptotic stability theorem, so the parameters of the VGC does not affect the system stability. Then, in order to meet the requirement of quick dynamic response and no overshoot, parameters selection of VGC is deduced by mathematics. Finally, the co-simulation of Matlab/Simulink and Carsim results show that the proposed control strategy is with the better dynamics and stability, and can better prevent wheel slipping on various roads.

International audience; It is of importance to design observers for multi-variable nonlinear systems with unknown parameters and partially driven by unknown inputs. Such a problem arises in systems subject to disturbances or with inaccessible inputs and in many applications such as parameter identification, fault detection and isolation or cryptography. In this paper, the problem of fixed-time observation for nonlinear dynamical systems with unknown parameter and inputs is studied. Conditions on full/partial state and parameters identification are provided by the the way of an observation algorithm based on differential geometry theory. Then, an uniform differentiator for estimating simultaneously the states and unknown parameters in fixed-time while avoiding observability singularities is designed. An example on topology identification of network systems is described to show the effectiveness of the proposed method.

Nanoparticle delivery to solid tumours over the past ten years has stagnated at a median of 0.7% of the injected dose. Varying nanoparticle designs and strategies have yielded only minor improvements. Here we discovered a dose threshold for improving nanoparticle tumour delivery: 1 trillion nanoparticles in mice. Doses above this threshold overwhelmed Kupffer cell uptake rates, nonlinearly decreased liver clearance, prolonged circulation and increased nanoparticle tumour delivery. This enabled up to 12% tumour delivery efficiency and delivery to 93% of cells in tumours, and also improved the therapeutic efficacy of Caelyx/Doxil. This threshold was robust across different nanoparticle types, tumour models and studies across ten years of the literature. Our results have implications for human translation and highlight a simple, but powerful, principle for designing nanoparticle cancer treatments. Efficient nanoparticle delivery into tumours has been a challenge in the field. It is now shown that the efficiency can be improved substantially when the dose breaches a specific threshold.

International audience; In this article, an observer‐based adaptive boundary iterative learning control law is developed for a class of two‐link rigid‐flexible manipulator with input backlash, the unknown external disturbance, and the endpoint constraint. To tackle the backlash nonlinearities and ensure the vibration suppression, the disturbance observers based upon the iterative learning conception are considered in the adaptive boundary control design. A barrier Lyapunov function is incorporated with boundary control law to restrict the endpoint state. Based on the defined barrier composite energy function, the tracking angle error convergence of the rigid part is guaranteed, and the vibrations of the flexible part are suppressed through the rigorous analysis. Finally, a numerical simulation is provided to illustrate the effectiveness of the proposed control.

Coastal lagoon–tidal inlet systems occur worldwide, and each has its own unique evolution characteristics in relation to its geographical location, sediment characteristics, and tidal current and ocean wave conditions. However, insufficient observation data means that it is often difficult to fully understand the long-term and short-term evolution of ebb-tidal deltas, and it is even more difficult to monitor and warn against their evolution. This study uses long time-series remote sensing data for the period 1962–2018 to investigate the evolution of an ebb-tidal delta in Xincun Lagoon, Hainan Island, China. Four shoal-sandbar breaching and tidal-inlet migration events were observed, and the corresponding periodic variation characteristics of the ebb-tidal delta were documented. A conceptual model for the periodic evolution of ebb-tidal deltas was also proposed. The results showed that the long-period (15–20 years) evolution was controlled by the effects of seabed friction and tidal-scale lagoon resonance, while the changes in the length of the east sand-spit could be used as a significant early warning indicator for shoal-sandbar breaching and tidal-inlet migration events. In addition, both types of event were jointly triggered by typhoon storm-surges and the accompanying heavy rainfall, strong winds, and strong waves. Thus, the periodic evolution process of the ebb-tidal delta in Xincun Lagoon was determined to be a systematic process that is either controlled or influenced by a series of interconnecting factors. Moreover, we concluded that it is both feasible and valuable to establish a monitoring and early warning framework of ebb-tidal deltas through the use of time-series remote sensing images. The results of this study can improve the existing understanding of the processes and driving factors of periodic shoal-sandbar breaching and tidal-inlet migration, and can also increase safety nourishment for coastal lagoon–tidal inlet systems.

Metal-organic frameworks (MOFs) are an emerging class of catalysts that posess large surface area due to intrinsic porosity, and high metal loading. However, they often lack catalytic properties due to the saturated coordination sphere of metal centres. Some MOFs have been found to exhibit good to excellent catalytic activity in a limited number of reactions, resulting from solvent induced changes of the coordination sphere. In this work the coordination sphere changes of Cu(bpy)(H2O)2(BF4)2(bpy) (bpy = 4,4-bipyridine) affected by common solvents with different dipole moments were studied by means of solution-state 1H and 19F NMR. It was found that organic molecules interact with the copper(II) centre and cause structural transformations of Cu-MOF in proportion to both the dipole moment and concentration of solvent. The sensitive NMR resonances reveal an exchange of the BF4¯ anions to DMSO (dimethylsulfoxide) molecules at axial positions of Cu(II) and even breakage of Cu-N and Cu-O bonds in equatorial positions with increasing DMSO concentration. Therefore, solvents with suitable dipole moments (1.7–3.9) can promote structural changes and, thus release highly active sites in the reaction, which can efficiently enhance the activity of Cu-MOF catalysts.

Wheel slipping of four-wheel independent drive electric vehicle on slope will reduce vehicle controllability and driving stability, thereby reducing vehicle safety. In order to solve the problem of wheel slipping and optimize the speed control performance of four-wheel independent drive electric vehicle on slope, an acceleration slip regulation control strategy of slope drive is proposed in this paper. First, we design a road identification algorithm to identify the current road conditions of the four-wheel independent drive electric vehicle, and calculate the optimal slip ratio of the current road surface by curve fitting method. Then, with the optimal slip ratio as the control objective, the acceleration slip regulation control strategy is designed to maximize the utilization of wheel adhesion coefficient to prevent wheel slip. Third, a slope identification algorithm based on Luenberger state observer is designed to identify the various slopes of the uphill and downhill road, after which a torque compensation algorithm is designed according to the identification slope, to compensate for the longitudinal component of vehicle gravity at different slopes. Fourth, a slope torque distribution algorithm is proposed based on acceleration slip regulation and slope identification. Finally, through the joint simulation platform of MATLAB/Simulink and CarSim, it is shown that the proposed control strategy can better restrain wheel slipping on the uphill and downhill road, and has better dynamic characteristics and stability.

Organic matter–disseminated sand (OMDS) is a widely distributed problematic soil in coastal areas of Hainan province, China. Its existence makes the installation of piles difficult and has the risk of insufficient bearing capacity. OMDS is different from other organic soils such as peat in terms of formation, mineral component, organic content, and forms of organic matters. In this study, 20% (w/w) cement together with 7.5% (w/w) lime at a water–cement ratio of 0.45 was mixed with OMDS to improve its mechanical performances. A series of unconsolidated undrained static triaxial test was conducted on the stabilized OMDS to investigate the failure mode, stress–strain relationship, maximum and residue deviator stress, axial strain at failure, and elastic modulus under various confining pressures (0, 200, 300, 400 kPa) and curing time (7d, 14d, 28d). The test results showed that higher confining pressure and longer curing time in general led to higher maximum and residue deviator stress, larger axial strain at failure, and larger secant elastic modulus of cement-stabilized OMDS. The maximum and residue deviator stress of cement-stabilized OMDS increased with curing time and ranged from 500 to 2180 kPa and from 250 to 1800 kPa, respectively. Under elevated confining pressure, maximum deviator stress increased substantially, irrespective of curing time. Secant elastic modulus (E50) increased with confining pressure at these three curing time, from 29 to 42 MPa. Due to the existence of organic matters, the strength of cement-stabilized OMDS was lower than cement-stabilized non-organic sand, regardless of confining pressure and curing time. This study provided new insight into the shear strength behavior of cement-stabilized OMDS under different confining conditions. This will facilitate the design and construction of foundations in this type of soil.

This study focuses on the stability of stone column-supported and geosynthetic-reinforced embankments on soft soil. An upper-bound limit state plasticity failure discretization scheme (known as discontinuity layout optimization (DLO)), which determines the embankment stability without pre-assuming a slip surface, is used. The relationships between the stability of stone column-supported and geosynthetic-reinforced embankments and various influencing parameters, including the soil strength, geometric configuration, reinforcement strength, and area replacement ratio, are analysed. It is found that geosynthetics provide a significant contribution to embankment stability. Two failure mechanisms of geosynthetics (i.e., rupture failure and bond failure) are revealed and the effect of geosynthetics on embankment stability is governed by the failure mode. The application of stone columns mitigates the risk of geosynthetic failure. To provide an analytical solution for primary design in engineering practice, an approach based on the limit equilibrium method is proposed. Validations are performed with the DLO solution to demonstrate the accuracy and reliability of the developed analytical approach.

In this article, a novel artificial intelligence method, i.e. random forest (RF), was adopted as a computer-aided tool to predict the vertical displacement of several pile-supported bridge piers ab...

Porphyrin aggregates have attractive photophysical properties for phototherapy and optical imaging, including quenched photosensitization, efficient photothermal conversion, and unique absorption spectra. Although hydrophobic porphyrin photosensitizers have long been encapsulated into liposomes for drug delivery, little is known about the membrane properties of liposomes with large amphiphilic porphyrin compositions. In this paper, a porphyrin-lipid conjugate was incorporated into liposomes formed of saturated or unsaturated lipids to study the membrane composition-dependent formation of highly ordered porphyrin J-aggregates and disordered aggregates. Porphyrin-lipid readily phase-separates in saturated membranes, forming J-aggregates that are destabilized during the ripple phase below the main thermal transition. Porphyrin-lipid J-aggregates are photostable with a photothermal efficiency of 54 ± 6%, comparable to gold. Even at high porphyrin-lipid compositions, porphyrin J-aggregates coexist with a minority population of disordered aggregates, which are photodynamically active despite being fluorescently quenched. For photothermal applications, liposome formulations that encourage porphyrin-lipid phase separation should be explored for maximum J-aggregation.

With the continuous development of space and sensor technologies during the last 40 years, ocean remote sensing has entered into the big-data era with typical five-V (volume, variety, value, velocity and veracity) characteristics. Ocean remote-sensing data archives reach several tens of petabytes and massive satellite data are acquired worldwide daily. To precisely, efficiently and intelligently mine the useful information submerged in such ocean remote-sensing data sets is a big challenge. Deep learning—a powerful technology recently emerging in the machine-learning field—has demonstrated its more significant superiority over traditional physical- or statistical-based algorithms for image-information extraction in many industrial-field applications and starts to draw interest in ocean remote-sensing applications. In this review paper, we first systematically reviewed two deep-learning frameworks that carry out ocean remote-sensing-image classifications and then presented eight typical applications in ocean internal-wave/eddy/oil-spill/coastal-inundation/sea-ice/green-algae/ship/coral-reef mapping from different types of ocean remote-sensing imagery to show how effective these deep-learning frameworks are. Researchers can also readily modify these existing frameworks for information mining of other kinds of remote-sensing imagery.

Sonodynamic therapy (SDT) is a promising therapeutic platform for minimally invasive cancer treatment in which acoustically susceptible drug agents, sonosensitizers, are activated by deep-tissue-penetrating low frequency ultrasound. Despite growing research in recent years, the field has yet to clearly elucidate broadly applicable mechanisms by which acoustic cavitation triggers sonosensitizer therapeutic activity, creating difficulties in achieving substantial and translatable therapeutic efficacy. In this review, we will critically analyze the proposed mechanisms underlying SDT and overview how nanomedicines can complement and extend these mechanisms to deliver more efficacious SDT. In doing so, we aim to highlight potential avenues toward viable implementation of SDT as a cancer therapy.

Excavations may cause excessive ground movements, resulting in potential damage to laterally adjacent tunnels. The aim of this investigation is to present a simple assessment technique using a multivariate adaptive regression splines (MARS) model, which can map the nonlinear interactions between the influencing factors and the maximum horizontal deformation of tunnels. A high-quality case history in Tianjin, China, is presented to illustrate the effect of excavation on the tunnel deformation and to validate the FEM. The hypothetical data produced by the FEM provide a basis for developing the proposed MARS model. Based on the proposed model, the independent and coupled effects of the input variables (i.e. the normalized buried depth of tunnels Ht/He, the normalized horizontal distance between tunnels and retaining structures Lt/He, and the maximum horizontal displacement of retaining structures, δRmax) on the tunnel response are analysed. The prediction precision and accuracy of the MARS model are validated via the artificial data and the collected case histories.

In this paper, a study on whether the use of polymer would affect the engineering properties of marine clay during and after the consolidation stage was carried out. A polymer, polyacrylamide (PAM)...

Barnacles mating optimizer (BMO) is an evolutionary algorithm that simulates the mating and reproductive behavior of barnacle population. In this article, an improved Barnacles mating optimizer based on logistic model and chaotic map (LCBMO) was proposed to produce the high-quality optimal result. Firstly, the logistic model is introduced into the native BMO to realize the automatic conversion parameters. This strategy maintains a proper relationship between exploitation and exploration. Then, the chaotic map is integrated to enhance the exploitation capability of the algorithm. After that, six variants based on LCBMO are compared to find the best algorithm on benchmark functions. Moreover, to the knowledge of the authors, there is no previous study on this algorithm for multilevel color image segmentation. LCBMO takes Masi entropy as the objective function to find the optimal threshold. By comparing different thresholds, different types of images, different optimization algorithms, and different objective functions, our proposed technique is reliable and promising in solving color image multilevel thresholding segmentation. Wilcoxon rank-sum test and Friedman test also prove that the simulation results are statistically significant.

Background: There has been growing interest in nanobubbles for their potential to extend bubble-mediated ultrasound approaches beyond that of their larger microbubble counterparts. In particular, the smaller scale of nanobubbles may enable them to access the tumor extravascular compartment for imaging and therapy in closer proximity to cancer cells. Compelling preliminary demonstrations of the imaging and therapeutic abilities of nanobubbles have thus emerged, with emphasis on their ability to extravasate. However, studies to date rely on indirect histologic evidence that cannot confirm whether the structures remain intact beyond the vasculature - leaving their extravascular potential largely untapped. Methods: Nanobubble acoustic scattering was assessed using a recently reported ultra-stable formulation at low concentration (106 mL-1) and frequency (1 MHz), over a range of pressures (100-1500 kPa) in a channel phantom. The pressure-dependent response was utilized as a basis for in vivo experiments where ultrasound transmitters and receivers were integrated into a window chamber for simultaneous intravital multiphoton microscopy and acoustic monitoring in tumor-affected microcirculation. Microscopy and acoustic data were utilized to assess passive and active delivery of nanobubbles and determine whether they remained intact beyond the vasculature. Results: Nanobubbles exhibit pressure-dependent nonlinear acoustic scattering. Nanobubbles are also found to have prolonged acoustic vascular pharmacokinetics, and passively extravasate intact into tumors. Ultrasound stimulation of nanobubbles is shown to actively enhance the delivery of both intact nanobubbles and shell material, increasing their spatial bioavailability deeper into the extravascular space. A range of acute vascular effects were also observed. Conclusion: This study presents the first direct evidence that nanobubbles passively and actively extravasate intact in tumor tissue, and is the first to directly capture acute vascular events from ultrasound-stimulation of nanobubbles. The insights gained here demonstrate an important step towards unlocking the potential of nanobubbles and extending ultrasound-based applications.

International audience; In this paper, we investigate the observation and stabilisation problems for a class of linear time-invariant systems, subject to unknown states, and network constraints, including time-delays and event-triggered sampling. A new type of event-triggered mechanism is proposed based on an appropriate storage function, which is chosen larger than the derivative of Lyapunov function. Thus, the convergence of the observer system is guaranteed by the negativity of this storage function. With the utilisation of LMI techniques and the designed novel event-triggered mechanism, as well as the utilisation of a Wirtinger-based inequality, only a slight over-estimation exists in the process of obtaining stability conditions, leading to reduced conservatism. With simulations of a mobile cart system, the effectiveness of this novel event-triggered mechanism is proven through a comparison with a classical event-triggered and also periodic time-triggered mechanisms.

International audience

International audience; Compliant Mechanisms (CMs) present several desired properties for mechanical applications only depending on elastic deformation of the involved compliant beams/flexures. As reported in the current literature, most CM designs utilize straight beams and initially curved beams (ICBs) as the fundamental flexible members. In CM research community, many great contributions regarding modeling these elementary flexible members have been achieved. In this paper, a comprehensive modeling methodology, based on beam theory, has been established to characterize the static planar deflection of slender beam. Then such a methodology has been applied to solve 8 loading scenarios of large beam-deflection problems that exist in the design of CMs. Essentially speaking, all these beam-deflection problems are treated as a type of boundary value problems (BVPs) of an ordinary differential equation (ODE) and solved by a modified collocation method. After that, this methodology has been used to model some representative CMs with large-deflection strokes, such as compliant parallelograms.

Compliant mechanisms (CMs) are used to transfer motion, force, and energy, taking advantages of the elastic deformation of the involved compliant members. A branch of special type of elastic phenomenon called (post) buckling has been widely considered in CMs: avoiding buckling for better payload-bearing capacity and utilizing post-buckling to produce multi-stable states. This paper digs into the essence of beam’s buckling and post-buckling behaviors where we start from the famous Euler–Bernoulli beam theory and then extend the mentioned linear theory into geometrically nonlinear one to handle multi-mode buckling problems via introducing the concept of bifurcation theory. Five representative beam buckling cases are studied in this paper, followed by detailed theoretical investigations of their post-buckling behaviors where the multi-state property has been proved. We finally propose a novel type of bi-stable mechanisms termed as pre-buckled bi-stable mechanisms (PBMs) that integrate the features of both rigid and compliant mechanisms. The theoretical insights of PBMs are presented in detail. To the best of our knowledge, this paper is the first study on the theoretical derivation of the kinematic models of PBMs, which could be an important contribution to this field.

This paper investigates event-triggered (ET) observers for output-sampled nonlinear state affine systems ( x = A ( u ) x + b ( u ) ). In particular, the sampling of the system’s output is aperiodic and decided by a designed system performance based event-triggered mechanism (ETM). Under this novel ETM, the global exponential stability of the observer system is guaranteed. The continuous state estimation is derived by using aperiodic sampled system output. The effectiveness of the proposed observer has been illustrated on a numerical example. For the special constant case of the considered system ( A ( u ) = A ), an LMI based ET observer is also proposed, and finally compared to the system performance based ET observer in a mobile cart system example.

International audience; A procedure of upgrading a linear observer to homogeneous (nonlinear) one is proposed and validated by experiment. The nonlinear observer design is based on the the concept of a linear geometric homogeneity. The simple procedure developed to apply the homogeneous nonlinear observer is based on the parameters provided by the linear observer, which is potential for many applications to improve their performance. A saturation function is introduced to guaranteed the improvement of estimation quality. Finally the theoretical results are confirmed by the QDrone platform of Quanser T M .

Compliant Mechanisms (CMs) present several desired properties for mechanical designs. Conventional rigid-body mechanisms composed of rigid links connected at kinematic joints, serve as devices to transfer motion, force and energy by the movements of rigid links whereas CMs are able to present the same function only through deflection of flexible members. Most designs of CMs in the current literature employ straight beams as the elementary flexible members whereas initially curved beams (ICBs) also provide potential advantages for CMs such as large range of motion and small strain range. This paper presents an efficient spatial compliance analysis method of general ICBs. The spatial compliance analysis of different types of ICBs (such as varying-curvature beams and varying-cross-section beams) was conducted, followed by Finite Element Analysis (FEA) verification. Next, the modeling and optimization of two types of CMs including ICB-based parallelogram mechanisms and ICB-based Ortho-planar springs were carried out by applying screw theory under the framework of position space concept and parameter normalization strategy where a class of anti-buckling translational parallelograms with high load-bearing capacity and a type of compact 2R1T (2 rotational DOF and 1 translational DOF) compliant kinematic joints were obtained. The corresponding FEA was conducted to verify the optimal results.

Embankment stability issues present design and research challenges to geotechnical engineers. Current design methodologies for the stability of embankments on columns are mainly evaluated ...

X-ray induced photodynamic therapy enables chemotherapy-free treatment of deep-tissue cancer with a low dose of X-ray radiation.

Stem cell technology can be used in tissue engineering and regenerative medicine to transplant stem cells of somatic, embryonic, or induced pluripotent origin, which have tremendous potential for the treatment of currently incurable diseases. Stem cells can maintain their stemness through their self-renewal capability while promoting tissue repair and regeneration through differentiation into various target tissue cells. These two major processes of stem cell biology are precisely regulated via extracellular and intracellular signals. Gaseous signaling molecules have recently been identified to play important roles in both physiology and pathophysiology, and inhalable nitric oxide (iNO) has even been applied as a therapeutic agent. Compared with chemical formulations, these molecules have lower molecular weights and are more likely to pass through the blood-brain barrier and between cells. Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S), three major gaseous signaling molecules involved in biological functions, are emerging as regulators of stem cell processes such as self-renewal, differentiation, survival, anti-apoptotic effects, proliferation, and immune rejection. Although many reviews concerning the roles of gaseous signaling molecules in different diseases or systems are available, few have focused on the roles of these molecules in the regulation of stem cells. Therefore, the aim of this paper is to systematically review the current literature on the functions and mechanisms of the gaseous signaling molecules NO, H2S, and CO in different types of stem cells and to summarize the effects of these molecules on stem cell biology and in therapy.

This article presents a novel technique for automatically locating tropical cyclone (TC) centers based on top cloud motions in consecutive geostationary satellite images. The high imaging rate and spatial resolution images of the Gaofen-4 geostationary satellite enable us to derive pixel-wise top cloud motion data of TCs, and from the data, TC spiral centers can be accurately determined based on an entirely different principle from those based on static image features. First, a physical motion field decomposition is proposed to eliminate scene shift and TC migration in the motion data without requiring any auxiliary geolocation data. This decomposition does not generate the artifacts that appear in the results of the previously published motion field decomposition. Then, an algorithm of a motion direction-based index embedded in a pyramid searching structure is fully designed to automatically and effectively locate the TC centers. The test shows that the TC concentric motions are more clearly revealed after the proposed motion field decomposition and the located centers are in good agreement with the cloud pattern centers in a visual sense and also with the best track data sets of four meteorological agencies.

Core samples to a depth of approximately 50 m and undisturbed soil samples were retrieved from eight locations in the Saga Plain, Japan, to investigate the effects of the depositional environment and post-depositional processes on the engineering properties of Quaternary clays in the Saga Plain. The engineering properties of these soil samples were measured, and the test results showed that the clays in the Saga Plain have a high void ratio, high water content, high compressibility, high sensitivity, and low stiffness. The one-dimensional compression curves plotted above the sedimentation compression line proposed by Burland, and the compression index was high, which indicated that the clays had been cemented to some degree. The clays have high strength sensitivity and high stress sensitivity, indicating that they have strong structures. It was considered that a considerable amount of volcanic ash from the four large volcanic eruptions that occurred during the deposition of these clays settled into the clays, resulting in a certain degree of cementation, which was attributed as the main driver of the strong structure in these clays. Comparisons of the NaCl concentration, pH, and oxidation-reduction potential (ORP) of the clay samples representing the initial depositional environment and the current ground environment showed that salt leaching occurred in the Ariake clay formation, and that the ground environment changed. When the NaCl concentration was less than approximately 2 g/L, the strength sensitivity of the Ariake clay samples with low-activity clay minerals significantly increased due to the decrease in the liquid limit and subsequent significant decrease in the remolded undrained shear strength. Therefore, salt leaching was probably a main cause of the high strength sensitivity of the clays in the Saga Plain. The depositional environment at some locations changed from an alkaline, reducing environment, to an acidic, oxidative environment, with the potential to change into a strongly acidic environment, which could have deteriorated the strength of the cement/lime-treated clays in the Saga Plain.

The uniform rigidity ring model is commonly used to design the segmented structures of shield tunnels. However, model tests have been primarily used to study the transverse effective rigidity ratio η with a concentrated force, which is notably different from realistic loading patterns. To obtain more reasonable η values, in this study, tests were performed with a concentrated load on an experimental bench and with a realistic loading pattern in sandy soil in a rigid steel tank. Three types of segmental ring models were designed and tested: straight-jointed, stagger-jointed, and uniform rings. The test results indicated that the η values of the stagger-jointed assembly mode were clearly larger than those of the straight-jointed assembly mode under both loading patterns. η increased as the load increased under the realistic loading conditions, whereas η decreased as the load increased under the concentrated load. More importantly, the η values derived from the realistic load tests were considerably larger than those derived from the concentrated load tests for both assembly modes (i.e., 0.423–0.672 and 0.587–0.761 for the straight-jointed and stagger-jointed assembly modes, respectively), and the former should be recommended for practical engineering applications. Furthermore, formulas relating η to the ratio of the cover depth to the tunnel diameter were proposed for sandy soil.

Assessment of the ultimate bearing capacity of foundations adjacent to slopes is complex as it is highly dependent on the slope geometry and soil properties. Seismic loading may impact both the critical failure mechanism and its associated bearing capacity. The existing approaches for analyzing the seismic bearing capacity of footings near slopes typically employ coefficients developed to fit the conventions of Terzaghi’s bearing capacity equation, herein referred to as the “superposition method.” In this study, a rigorous assessment of the seismic bearing capacity is performed using an upper-bound limit state plasticity framework known as discontinuity layout optimization (DLO), which makes few prior assumptions concerning the failure geometry. Results show that soil properties, slope configuration, and pseudostatic seismic loading all influence the realized failure mechanism and associated bearing capacity. The use of bearing capacity coefficients that fit within the conventional superposition method may underestimate limit loads when the underlying soil provides a relative increase in resistance, but may greatly overestimate bearing capacity when the self-weight of the soil is destabilizing in nature. A set of design charts using direct computational methods for a variety of geometric, geotechnical, and seismic conditions is provided.

In this paper, gold nanoparticles (AuNPs) modified by thiolated calix[n]arene (TCnA, n = 4, 6, 8) were anchored on graphene nanosheets (GN) by π-π stacking interaction between TCnA molecules and GN. Testing of various electrochemical techniques display that the AuNPs@TCnA/GN modified glass carbon electrodes (GCE) show good electrocatalytic property, molecular recognition and enrichment performance toward dopamine (DA) and acetaminophen (AC), and exhibit high current response. In all of modified electrodes, AuNPs@TC8A/GN/GCE shows an outstanding electrochemical response for DA and AC with high sensitivity of 5.08 and 9.76 mA mmol−1 L cm−2, respectively. The analytical curves for DA obtained by differential pulse voltammetry (DPV) are linear in the range from 0.5 to 150 μM and from 0.3 to 1.0 mM. The linear range for AC obtained by DPV is from 0.5 to 120 μM. Besides, AuNPs@TC8A/GN/GCE can be applied to determinate of DA and AC simultaneously, implying the prospect to develop a dual sensor under the same construction platform.

A nanoemulsion with a porphyrin shell (NewPS) was created by the self-assembly of porphyrin salt around an oil core. The NewPS system has excellent colloidal stability, is amenable to different porphyrin salts and oils, and is capable of co-loading with chemotherapeutics. The porphyrin salt shell enables porphyrin-dependent optical tunability. The NewPS consisting of pyropheophorbide a mono-salt has a porphyrin shell of ordered J-aggregates, which produced a narrow, red-shifted Q-band with increased absorbance. Upon nanostructure dissociation, the fluorescence and photodynamic reactivity of the porphyrin monomers are restored. The spectrally distinct photoacoustic imaging (at 715 nm by intact NewPS) and fluorescence increase (at 671 nm by disrupted NewPS) allow the monitoring of NewPS accumulation and disruption in mice bearing KB tumors to guide effective photodynamic therapy. Substituting the oil core with Lipiodol affords additional CT contrast, whereas loading paclitaxel into NewPS facilitates drug delivery.

This paper assesses different retrieval schemes used for the Chinese Gaofen-3 Synthetic Aperture Radar (GF-3 SAR) co-polarized data. The data consist of 4186 GF-3 data points and collocated wind information from sources including the ASCAT scatterometer, HY2A-SCAT scatterometer, and National Data Buoy Center (NDBC) buoy wind data set. The VV-polarized geophysical model function (GMF) is a CMOD7 model while the HH-polarized GMF is a hybrid of the CMOD7 and PR model. Assessments involve comparisons between SAR-derived and collocated winds in terms of the root-mean-square difference (RMSD) and bias. First, a comparison between the two retrieval schemes for the VV-polarized data clearly shows that the optimal scheme performs better than the classical scheme for wind speed retrieval. Comparisons for HH-polarized data show similar results. These experiments indicate that the wind speed RMSDs for the GF-3 co-polarized data are within 2 m/s when using the optimal scheme. Moreover, the wind direction RMSDs from the two schemes have no significant difference, with values near 20°. Overall, these assessments indicate that the GF-3 co-polarized data are sufficient for operational wind speed retrieval using the optimal scheme. However, wind direction retrieval requires further improvement.

Accurate estimates of aquifer parameters are necessary for effective groundwater management and for geotechnical engineering applications. Pumping tests may be employed to estimate the hydraulic conductivity in leaky aquifer/aquitard systems. This work introduces a hybrid algorithm with global search capacity (the Genetic algorithm, GA) and local search capacity—the Levenberg-Marquardt (LM) algorithm—coupled with a modified Neuman-Witherspoon solution for leaky aquifers to estimate the aquifer’s hydraulic parameters from pumping-test data. The GA is employed to determine the initial guesses of the aquifer parameter values. The optimal parameter values are then obtained with the LM algorithm, yielding a mixed GA/LM algorithm, herein named GALMA. Results show that the drawdown trends based on the estimated parameters agree well with measured drawdown. The proposed estimation algorithm identifies aquifer parameters with greater reliability than previous approaches. Verification of the GALMA is carried out based on three pumping tests in a layered aquifer in Tianjin, China, and on four historical case studies involving diverse hydrogeological settings. The excellent match between observed drawdown and GALMA-estimated parameters demonstrates the estimation accuracy and superior performance relative to previously reported estimation methods.