In order to alleviate the impact of the old bridge by the environment and its own life and the problem of increasing maintenance cost, the intelligent building integrated evaluation system based on ...BIM technology is proposed. Firstly, based on BIM technology, an all-weather hardware monitoring system is constructed by using multiple sensors laid on the bridge. The software communicates with the monitoring system through 5G public network and applies the unique advantages of deep neural network in classification to the assessment of the health status of old bridges with the help of the multiclassification convolutional neural network embedded in the software. The test results show that the preprocessed data is imported into the health diagnosis module for training, and the training accuracy reaches about 70%, and the loss curve is stable at about 0.5. Conclusion. The system meets the design requirements and solves the problem of difficult health diagnosis caused by long monitoring period and low efficiency of old bridges. The system has advantages of low difficulty in obtaining parameters, high precision, and accurate health assessment.
In this paper, a novel dynamic model of coupling translation joints with subsidence for time-varying load in a planar mechanical system is established. One translational joint has four working ...scenarios, which are free motion, one corner rub-impact, two adjacent corners rub-impact and two opposite corners rub-impact. However, the rub-impact of double coupling translation joints are not a simple superposition of these scenarios, but rather a more complex rub-impact configuration that should be considered in this model. An adaptive fourth-order Runge–Kutta method is utilized to solve the dynamic differential equations. After that, we discuss the dynamic behavior of the rub-impact coupling by taking a triplex member of the crosshead slider, piston rod and piston slider as an example in the reciprocating compressor system. The results show that the double coupling translation joints experience free motion, continuous contact motion and rub-impact motion. The difference is that, in the rub-impact motion, for the crosshead slider there only appears one single corner and two adjacent corners impacting the guide, while the coupling piston slider experiences multiple rub-impact situations including one single corner, two adjacent corners and two opposite corners impacting the guide. Moreover, the results reveal that the subsidence has a significant influence on the rub-impact behavior of the coupling translation joints, and the greater the subsidence, the more severe the vibration response of the slider impacting the guide. Finally, in this rub-impact coupling system, the existence of chaotic behavior is confirmed by the Poincaré section and the largest Lyapunov exponent approaches.
To study the influence of the geometric structure of the probe coil on the electromagnetic characteristics of the eddy current probe in the process of eddy current testing, based on the principle of ...eddy current testing, different probe coil models were established using finite element software. These geometric structure parameters include the difference between the inner and outer radius, thickness, and equivalent radius. The magnetic field distribution around the probe is simulated and analyzed under different parameters, and the detection performance of the probe is judged in combination with the change rate of the magnetic field around the probe coil. The simulation results show that at a closer position, increasing the difference between the inner and outer radii, reducing the thickness, and reducing the equivalent radius are beneficial to improve the resolution of the probe coil. At a far position, reducing the difference between the inner and outer radii, increasing the thickness, and reducing the equivalent radius are beneficial to improve the resolution of the probe coil. At the same time, the accuracy of the simulation data is verified by comparing the theoretical values with the simulated values under different conditions. Therefore, the obtained conclusions can provide a reference and basis for the optimal design of the probe structure.
In this paper, a nonlinear dynamic model of the single-stage reciprocating compressor system with a rub-impact fault caused by subsidence is developed, considering the piston rod flexibility. ...Meanwhile, different rub-impact scenarios of the crosshead including no corner, a single corner, two opposite corners, and two adjacent corners of the crosshead impacting on the slide, are considered in this model. Numerical simulation results show that the subsidence, time-varying load, and piston rod flexibility have significant effects on the vibration response of the reciprocating compressor system with rub-impact, where the larger the subsidence and time-varying load, the more intense the vibration response. Moreover, compared to the rigid piston rod, the flexible piston rod causes the system to generate stronger shock. In the rub-impact, the crosshead appeared in three different motion modes: noncontact; permanent contact; and collision – and most of the collisions occur in the form of two adjacent corners impacting on the slide. In addition, strange attractors are observed in the phase space trajectories, and the existence of chaotic behavior is verified using the Poincaré section method and maximum Lyapunov exponent method.
Customer citizenship behavior in the online shopping environment is vital to the success of e-retailers. However, it is unclear whether and how service recovery expectation and recovery justice ...predict customer citizenship behavior in e-retailing settings. Grounded on the expectation confirmation theory and social exchange theory, this study examined the influence of service recovery expectation and recovery justice on customer citizenship behavior with a serial mediation of recovery expectation confirmation and post-recovery satisfaction. A total of 774 samples from e-shoppers with most impressive (
N
= 401) and most recent (
N
= 373) service recovery experience were collected to test the hypotheses using structural equation modeling and bootstrapping procedures. This study reveals that service recovery expectation has a negative impact on recovery expectation confirmation, while recovery justice positively affects recovery expectation confirmation, which is further positively correlated with post-recovery satisfaction and customer citizenship behavior. Moreover, recovery expectation confirmation and post-recovery satisfaction play a serial mediation in the relationship between service recovery expectation and recovery justice, and customer citizenship behavior. Our study contributes to the growing body of customer citizenship behavior literature by offering an alternative perspective (i.e., service recovery) to understand what encourage or impede customer citizenship behavior, and expands service recovery literature by combining service recovery expectation and recovery justice into a framework and revealing the expectation–confirmation mechanism through which they influence post-recovery satisfaction in online shopping setting.
Solar-driven CO2 conversion to chemical fuels in an aqueous solution is restricted not only by photocatalysts but also by mass transfer. Here, a regulatable three-phase interface on a porous ...fixed-bed is constructed for efficient C–C coupling in photocatalytic CO2 reduction. The photocatalytic results show that ∼90% selectivity towards C2+ products is obtained by a Cu/Cd0.5Zn0.5S photocatalyst, with a yield of 6.54 μmol/h (an irradiation area of 0.785 cm2), while only 0.94 μmol/h (an irradiation area of 19.625 cm2) is achieved with a commonly used suspension photocatalytic reactor. We find that under the same CO2 feed rate, the local CO2 concentration in this porous fixed-bed photoreactor is obviously higher than in the suspension photoreactor. The larger local CO2 coverage derived from a higher CO2 supply and aggregation enhances the C–C coupling, thereby generating more C2+. Even an observable three-phase interface on the porous fixed-bed can be regulated by adjusting the CO2 supply, for which the optimal gas inlet rate is 5–10 sccm.
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•A homemade porous fixed-bed photoreactor for overcoming the mass transfer bottleneck was designed and constructed.•A three-phase interface was formed and regulated by adjusting CO2 feed, while a K+ tracer experiment was used to observe it.•Local CO2 concentration from the three-phase interface enhanced ∗CO–COH coupling, with ∼90% selectivity to C2+ products.
In this work, based on the nine kinds of rub-impact scenarios of one single translational joint, we discuss 42 kinds of coupling rub-impact scenarios of double translational joints with subsidence ...for a triplex member including crosshead slider, piston rod, and piston slider. The two sliders are connected by a flexible piston rod. The flexible piston rod alternates between a straight rod and a S-curve rod in the rub-impact. A novel dynamic model of coupling rub-impact system with subsidence is established considering complex rub-impact scenarios and the flexibility of the piston rod. The dynamic equations are solved by the fourth-order Runge–Kutta approach. The numerical simulation results show that the subsidence has a significant effect on the rub-impact scenarios of the double translational joints, and the larger the subsidence is, the more intense the rub-impact. Moreover, the stability of coupling rub-impact system with double translational joints is investigated. The chaotic phenomenon of the coupling rub-impact system can be observed in the phase space trajectory. The existence of chaotic behavior is further confirmed by the Poincaré section method.
This paper focuses on designing a unified approach for computing the projection onto the intersection of a one-norm ball or sphere and a two-norm ball or sphere. We show that the solutions of these ...problems can all be determined by the root of the same piecewise quadratic function. We make use of the special structure of the auxiliary function and propose a novel bisection algorithm with finite termination. We show that the proposed method possesses quadratic time worst-case complexity. The efficiency of the proposed algorithm is demonstrated in numerical experiments, which show the proposed method has linear time complexity in practice.
8-Aminoquinoline (AQ) is a widely used bidentate auxiliary in metal-catalyzed directed C–H functionalization reactions. Herein, we report an efficient and chemoselective method to convert various ...N-quinolyl carboxamides to primary amides with the treatment of a stoichiometric amount of 2-iodoxybenzoic acid oxidant or the combination of a catalytic amount of 2-iodobenzoic acid and Oxone co-oxidant in mixed solvents of H2O and HFIP. Its unique compatibility with the Phth-protected α-amino acid (αAA) substrates enhances the overall synthetic utility of the AQ-directed palladium-catalyzed C–H functionalization strategy for synthesis of complex αAAs.
Although β-arrestins (ARRBs) regulate diverse physiological and pathophysiological processes, their functions and regulation in Parkinson's disease (PD) remain poorly defined. In this study, we show ...that the expression of β-arrestin 1 (ARRB1) and β-arrestin 2 (ARRB2) is reciprocally regulated in PD mouse models, particularly in microglia. ARRB1 ablation ameliorates, whereas ARRB2 knockout aggravates, the pathological features of PD, including dopaminergic neuron loss, neuroinflammation and microglia activation in vivo, and microglia-mediated neuron damage in vitro. We also demonstrate that ARRB1 and ARRB2 produce adverse effects on inflammation and activation of the inflammatory STAT1 and NF-κB pathways in primary cultures of microglia and macrophages and that two ARRBs competitively interact with the activated form of p65, a component of the NF-κB pathway. We further find that ARRB1 and ARRB2 differentially regulate the expression of nitrogen permease regulator-like 3 (Nprl3), a functionally poorly characterized protein, as revealed by RNA sequencing, and that in the gain- and loss-of-function studies, Nprl3 mediates the functions of both ARRBs in microglia inflammatory responses. Collectively, these data demonstrate that two closely related ARRBs exert opposite functions in microglia-mediated inflammation and the pathogenesis of PD which are mediated at least in part through Nprl3 and provide novel insights into the understanding of the functional divergence of ARRBs in PD.
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