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Inhibition of TICT can significantly increase the brightness of fluorescent materials. Accurate prediction of TICT is thus critical for the quantitative design of high-performance fluorophores and AIEgens. TICT of 14 types of popular organic fluorophores were modeled with time-dependent density functional theory (TD-DFT). A reliable and generalizable computational approach for modeling TICT formations was established. To demonstrate the prediction power of our approach, we quantitatively designed a boron dipyrromethene (BODIPY)-based AIEgen which exhibits (almost) barrierless TICT rotations in monomers. Subsequent experiments validated our molecular design and showed that the aggregation of this compound turns on bright emissions with ca. 27-fold fluorescence enhancement, as TICT formation is inhibited in molecular aggregates.

Three polysulfates P1, P2 and P3 containing two representative AIE-active groups, tetraphenyl ethylene and naphthylamide, were successfully synthesized based on a sulfur(VI) fluoride exchange (SuFEx) click reaction. Their solid fluorescence was studied in detail and liquid fluorescence emission could be tuned by choosing solvents with different polarities. P1 with a branched structure showed higher fluorescence emission than P2 and P3 both in the solid state and in organic solutions because of the more crowded local environment of the tetraphenyl ethylene group in the main chain. Moreover, all the polymers exhibited typical aggregation induced emission (AIE) effects in the solid state and in DMF/water solutions. Furthermore, their two-photon fluorescence behaviours were similar to their one-photon fluorescence behaviours in different organic solvents and in 90% DMF/water solutions. Interestingly, they could selectively detect cyanide ions with lower detection limits in water on account of the anion–π interactions between the naphthylamide groups and the cyanide ions. The detection limits of P1 (0.137 μM) and P2 (0.131 μM) are lower than P3 (0.145 μM), which may be attributed to the more exposed active sites of the P1 and P2 nanoparticles (NPs). All the results indicate that these polymers have higher sensitivity and better applicability for cyanide ion detection in water and in living cells.

This study provides a new embedded linear model (ELM) three-dimensional fuzzy PID control method for a bionic autonomous underwater vehicle (AUV), which is disturbed by ocean waves. The uncertainty of the ocean waves will make it difficult for the AUV to achieve good sailing quality, especially near the sea surface. In view of this problem, an ELM fuzzy PID controller, which adopts three-dimensional fuzzy control rules, is designed. In the ELM fuzzy PID controller, a linear model of AUV is established in order to actively perceive the effect of waves on AUV. Hence, the wave disturbance can be reflected in the control signal earlier and faster. Finally, three simulations are carried out to verify the control effect of the ELM fuzzy PID controller. An ocean wave disturbance model is established in order to simulate the force and the moment acting on the AUV. The results imply that compared with the classical PID controller and normal fuzzy PID controller, the ELM fuzzy PID controller can significantly enhance the stability of AUV and make the response faster and overshoot smaller.

This paper is devoted to solving the stacking sequence optimization problem of symmetrical laminated composite cylindrical shells subjected to hydrostatic pressure. First, a conventional genetic algorithm (GA) coupled with a finite element analysis optimization method is developed to search for the best laminations with the maximum buckling pressure. These optimal laminations share similar extensional stiffness coefficient ratios A11/A22 and bending stiffness coefficient ratios D11/D22 because the two ratios of the optimal lamination fluctuate slightly around a specific value. Based on this phenomenon, a stiffness coefficient-based method (SCBM) is then proposed. The method is integrated with the GA and the stiffness coefficient calculation to identify the lamination whose stiffness coefficient ratios (A11/A22 and D11/D22) are closest to those obtained previously. The effectiveness of the SCBM is validated by comparison with the optimal results. The proposed method is then extended to more complex symmetrical laminations. Finite element analysis is also coupled with the GA as a control group. Comparisons reveal that the two methods lead to similar characteristic lamination patterns and maximum buckling pressures, which suggests that the SCBM works well for complex laminations. Moreover, the SCBM is found to be significantly more efficient because it only needs to calculate the stiffness coefficients rather than analyse the entire structure during the optimization.

Materials that display aggregation induced emission (AIE) can offer large contrast ratio for highly sensitive fluorescence based applications such as sensing and imaging. Conventional AIE chromophores are generally based on improved emission quantum yield due to reduced nonradiative decay rates by restriction of intramolecular motion. In this work we present another type of AIE phenomenon with a totally different working mechanism. It is based on aggregation induced plasmon coupling of metal nanoparticles (NPs) to simultaneously enhance the excitation efficiency and radiative decay rate of chromophores. The unique surface plasmon resonance (SPR) properties of noble metal NPs can give rise to a significantly enhanced local electric field to modulate the optical properties of nearby chromophores. Plasmon coupling interactions between adjacent metal NPs can cause giant enhancement in the local electric field and consequently even stronger enhancing capability. The working principle was demonstrated by using rhodamine B isothiocyanate (RiTC) as the model chromophore and cysteine as the coupling agent to induce aggregation of noble metal NPs. The fluorescence of RiTC was pre-quenched by attaching to the surface of Au and core–shell Au@Ag NPs. Upon addition of cysteine to induce the aggregation of RiTC conjugated Au@Ag NPs, the fluorescence of RiTC was significantly enhanced to a level much beyond that of fluorescence recovery. A series of core–shell Au@Ag NPs with different Ag shell thicknesses have been prepared to optimize the performance of aggregation induced plasmon coupling enhanced fluorescence. The optimum enhancement effect was achieved for Au@Ag NPs with a 5.6 nm Ag shell, which enhanced the fluorescence intensity of RiTC in the coupled nanostructures to be 44.8 times stronger than that of pre-quenched RiTC and 7.6 times that of free RiTC. Based on this method, the limit of detection of 3.4 pM was obtained for the detection of cysteine, which is highly selective and more sensitive than most previously reported methods. This quenched-enhanced (off–on) method is highly sensitive, simple, straightforward and universal, and can be easily extended for the detection of other analytes.

In this research, a real-time nowcasting system for regional landslide-hazard assessment under extreme-rainfall conditions was established by integrating a real-time rainfall data retrieving system, a landslide-susceptibility analysis program (TRISHAL), and a real-time display system to show the stability of regional slopes in real time and provide an alert index under rainstorm conditions for disaster prevention and mitigation. The regional hydrogeological parameters were calibrated using a reverse-optimization analysis based on an RGA (Real-coded Genetic Algorithm) of the optimization techniques and an improved version of the TRIGRS (Transient Rainfall Infiltration and Grid-based Regional Slope-Stability) model. The 2009 landslide event in the Xiaolin area of Taiwan, associated with Typhoon Morakot, was used to test the real-time regional landslide-susceptibility system. The system-testing results showed that the system configuration was feasible for practical applications concerning disaster prevention and mitigation.

We consider static black holes in Einstein gravity and study parameters characterizing the black hole size, namely the radii of the horizon ${R}_{+}$, photon sphere ${R}_{\mathrm{ph}}$, and black hole shadow ${R}_{\mathrm{sh}}$. We find a sequence of inequalities $\frac{3}{2}{R}_{+}\ensuremath{\le}{R}_{\mathrm{ph}}\ensuremath{\le}\frac{1}{\sqrt{3}}{R}_{\mathrm{sh}}\ensuremath{\le}3M$, where $M$ is the black hole mass. These are consistent with and beyond the previously known upper bounds in literature. The Schwarzschild black hole saturates all the inequalities, making it the biggest of all for a given mass. The inequalities include an upper bound of entropy for any quantum system with a given energy. We also point out that some black holes satisfying the dominant energy condition can trap photons to form a stable photon shield outside the event horizon, but the shadow hides it from an observer at infinity.

With the increasing diameter of deep-water bored piles, the risk of buckling deformation of super-large-diameter steel casings (SLDSC) during the dynamic impact driving process has increased dramatically. However, the risk factors involved in this process are yet to be ascertained. This study is based on the Xihoumen Rail-Road Bridge project, in which the steel casing used in the pile foundation has a design diameter of 6.8 m. LS-DYNA simulation software was used for numerical modelling. The influences of factors such as the casing wall thickness, hammering output energy, and the initial defect ovality were considered. The stress response, displacement depth (z-displacement), and buckling characteristics of SLDSC under axial impact load were studied. The reliability of the numerical modelling was also verified. The results show that for thin walls, the generated axial stress is great, and it is likely that buckling deformation can occur, thereby making it more difficult to drive the SLDSC to the designed depth. Relatively small hammering energy is insufficient to drive the SLDSC to the desired depth. As the hammering energy continues to increase, the increasing rate of z-displacement drops, and it is more likely to trigger non-axisymmetric buckling and curling of the SLDSC. For great initial defect ovality, the non-axisymmetric axial critical stress is small and is likely to trigger deformation accidents of the SLDSC, in which the buckling characteristics develops along the initial defect. Finally, for SLDSC used in relevant projects, it is recommended to have a wall thickness of 74–76 mm and hammering output energy of 1800–2000 KJ to control the ovality below 30 mm during manufacturing and transportation. The research results can provide a theoretical basis for the reasonable determination of wall thicknesses for SLDSC, the usage and debugging of special hammering equipment, and the control of defects during the manufacturing and transportation processes, thereby reducing the risks of buckling and deformation accidents during the axial impact driving process.

Flapping foils have been widely studied with the aim of achieving improved self-propelling efficiency and developing a new type of energy harvester. This study investigated the interaction of a flapping foil and the oncoming von Karman wake generated by a D-section cylinder. Distance between foil and cylinder, flapping frequency, and foil thickness are studied for the effects on the hydrodynamic performance of the flapping foil. The highest propulsive efficiency with the value of 50.33% was obtained when the non-dimensional frequency was 0.3, and the flapping foil operated as an energy harvester when the oscillating frequency was close to that of the wake. Furthermore, the original drag-generating flapping motion provided thrust when the foil thickness reached 20%. The definition of energy transformation ratio (RET) was supplemented. Equations for the propulsive efficiency and energy harvesting efficiency were unified into one formula using RET. When the value was in the ranges of (−1,1) and (-Infinity, −1), the flapping foil operated as a propeller and an energy harvester, respectively. To summarize, the oncoming von Karman wake excited the flapping motion, indicating that a macro-underwater vehicle would perform better following a blunt body and an energy harvester with a flapping foil structure would work more efficiently behind underwater structures, such as the pillars of offshore platforms.

The usage of composite material helps reducing structure’s weight in many conditions. In this paper, The Composite Ring Stiffened Cylindrical Hulls used by Unmanned Underwater Vehicles is optimized in various depths. The optimization aims to reducing the weight of the composite ring stiffened cylindrical hulls. Two candidate composite materials, T700/Epoxy and B(4)5505/Epoxy, are chosen to form the outer shell and stiffeners. Number and shape of the stiffeners, ply angles, and the number of the plies are considered. The Multi-Island Genetic Algorithm (MIGA) is performed in MATLAB and a new two-step method is proposed in crossover operations. ANSYS parametric design language is integrated in optimization procedure to ensure the acceptance of the optimal result. The results reveal that the proposed two-step method for multi-island genetic algorithm is efficiency and robust in reducing the weight of the composite ring stiffened cylindrical hulls. The weight for optimized composite ring stiffened cylindrical hulls with T700/Epoxy shells and B(4)5505/Epoxy stiffeners is 10.5% lighter than that with single composite material when the operating depth is 200 m.

Winglet has been widely used in aviation industries to improve the performance of aircraft. However, according to the authors' knowledge, the effect of winglet on underwater gliders has not been investigated in detail. This paper aims to investigate the impact of winglet on hydrodynamic performance and gliding trajectory of a blended-wing-body underwater glider (BWBUG). The hydrodynamic performance of the BWBUG without winglet (BWBUG-I) is firstly calculated. Then the hydrodynamic performance of BWBUG with winglet (BWBUG-II) is analyzed and compared. To estimate the influence of winglet on gliding trajectory, a dynamic model is established by considering the buoyancy and pitch regulating system. From the CFD results, the lift force acting on the glider is increased by the winglet, while the drag force remains at the same level. The lift-to-drag ratio is thereby improved. By comparing trajectories, the average gliding ratio for BWBUG-II is 5.10, 2.2% higher than 4.99 for BWBUG-I. With the winglet, the extreme attack angle is reduced from 7.2° to 6.1° when switching from rising to diving. The steady gliding speed is improved by 6.3%, and the squat depth is reduced by 11% under particular condition.

AdS black holes show richer transition behaviors in extended phase space by assuming the cosmological constant and its conjugate quantity to behave like thermodynamic pressure and thermodynamic volume. We study the extended thermodynamics of charged dilatonic AdS black holes in a class of Einstein–Maxwell-dilaton theories that can be embedded in gauged supergravities in various dimensions. We find that the transition behaviors of higher dimensional dilatonic AdS black holes are different from the four dimensional counterparts, and new transition behaviors emerge in higher dimensions. First, there exists a standard Van der Waals transition only in a five dimensional dilatonic AdS black hole with two equal charges. Second, there emerges a new phase transition branch in negative pressure region in six and seven dimensional dilatonic black holes with two equal charges. Third, there emerge transition behaviors in higher dimensional black hole with single charge cases, which are absent in four dimensions.

Flapping foils are studied to achieve an efficient propeller. The performance of the flapping foil is influenced by many factors such as oncoming vortices, heaving amplitude, and geometrical parameters. In this paper, investigations are performed on flapping foils to assess its performance in the wake of a D-section cylinder located half a diameter in front of the foil. The effects of heaving amplitude and foil thickness are examined. The results indicate that oncoming vortices facilitate the flapping motion. Although the thrust increases with the increasing heaving amplitude, the propelling efficiency decreases with it. Moreover, increasing thickness results in higher efficiency. The highest propelling efficiency is achieved when the heaving amplitude equals ten percent of the chord length with a symmetric foil type of NACA0050 foil. When the heaving amplitude is small, the influence of the thickness tends to be more remarkable. The propelling efficiency exceeds 100% and the heaving amplitude is 10% of the chord length when the commonly used equation is adopted. This result demonstrates that the flapping motion extracts some energy from the oncoming vortices. Based on the numerical results, a new parameter, the energy transforming ratio (RET), is applied to explicate the energy transforming procedure. The RET represents that the flapping foil is driven by the engine or both the engines and the oncoming vortices with the range of RET being (0, Infini) and (−1, 0), respectively. With what has been discussed in this paper, the oncoming wake of the D-section cylinder benefits the flapping motion which indicates that the macro underwater vehicle performs better following a bluff body.

In this study, three full-scale orthotropic steel plates set with single U rib, double U ribs and three U ribs were fabricated based on the mechanical characteristics of Changhong bridge in Ningbo. Several displacement and strain measuring points were selected as the analysis indexes, and two loading modes of axial and biased loading were designed. The buckling shape, out of plane displacement and strain variation law of the components under different loading conditions were analyzed. The DIC method was used to analyze the buckling and force transfer mechanism of the component in the loading process. Moreover, the finite element simulation and parameter analysis were carried out under eight component parameters by using ANSYS software. Through the experimental and parameter analysis in this paper, the instability mode, change of out of plane displacement, strain distribution and force transfer mechanism of orthotropic steel plates under different loading modes were obtained, which can provide reference value for the stability study of orthotropic steel plate and orthotropic steel box girder.

Welding residual stress is inherent to welding of U-rib stiffened plates and it is a “fact of life” that must be accounted for by designers. In this study, the welding residual stresses of U-rib stiffened plates were investigated through numerical and experimental methods. The influencing factors on the welding residual stress are based on a) two full-scale residual stress tests and b) a series of numerical parameter analyses. Regarding the U-rib residual stress, the maximum tensile stress decreased as the U-rib thickness increased, whereas an opposite trend is observed for the maximum compression stress. For the subpanel residual stress, the maximum compressive stress increased with the increase of the U-rib thickness, while the maximum tensile stress decreased first and then increased. As the subpanel thickness increased, the maximum residual tensile/compressive stress and the maximum U-rib compressive stress decreased, and the U-rib tensile stress increased. The influence of the subpanel thickness on the residual stress is reduced as the U-rib thickness increased. The material yield strength has a minor effect on the extreme value of the residual stress of the subpanel and has a certain effect on the tensile stress distribution interval. The maximum residual tensile stress of the U-rib is approximately proportional to the material yield strength. According to these results, this study presents a simplified distribution diagram for the welding residual stress of the U-rib stiffened plate. It has been verified that the simplified distribution diagram can provide a valuable reference for the design of steel bridges.

Gold (Au) nanoparticles display enhanced near-infrared (NIR) photothermal effects upon the formation of clusters. We studied the photothermal properties of Au nanosphere clusters on the single-particle level using photothermal heterodyne imaging (PTHI) microscopy to understand the enhancement mechanisms. NIR photothermal responses of Au nanoparticle clusters were found to significantly increase from monomers to trimers. The averaged PTHI signal intensity of Au nanosphere dimers and trimers is ∼10 and ∼25 times that of monomers. The NIR photothermal effect of clustered nanospheres strongly correlates with their longitudinal plasmon mode. Clustered Au nanospheres were demonstrated to exhibit dual-capability NIR photothermal imaging and therapy of human prostate cancer cells with high efficiency and selectivity. This strategy can be potentially utilized for simultaneous cancer imaging and therapy with 3D selectivity.

This paper presents a practical methodology for designing group piles of a bridge foundation that can minimize the construction cost. The constraint functions for the designed pile group are constructed according to the design code currently adopted in local engineering practice. A new procedure based on the discrete Lagrange multiplier (DLM) method is proposed for searching the optimal solution. Seven real-world design cases are used to test the validity and the performance of the proposed procedure and algorithm, in which the DLM solutions are compared with the global optimum solutions obtained by the exhaustive searching method (ESM). Vast improvement in the computational efficiency is achieved, as the DLM method can find local minimum solutions in less than 2.0 to 4.0 minutes whereas the time required with the ESM is 10,000 to 25,000 times longer. In the case studies presented, the construction costs in conjunction with the use of the DLM method differ from the global minimum costs by less than 6.0%, but the savings over the original designs can be as high as 13% to 56%.

We study the conductivities and entanglement structures of two different holographic gapped systems at zero density in the presence of boundaries within AdS/BCFT. The first gapped system is described by the Einstein-scalar gravity and the second one is the dual of AdS soliton geometry. We show that in both these two systems the bulk and boundary conductivities along the spatial direction of the boundary of BCFT are trivial. For the first system, when we increase the size of the subsystem the renormalized entanglement entropy is always non-negative and monotonically decreasing with discontinuous, or continuous, or smooth behavior, depending on the effective tension of the brane. While for the AdS soliton with a boundary, the renormalized entanglement entropy only exhibits a discontinuous drop when we increase the size of the subsystem., Comment: 36 pages, 17 figures, published version