We aimed to enable an accurate assessment of the emergency capability of subway shield construction, and promote the construction of emergency capability of enterprises, so as to better guarantee the sustainable development of subway shield construction. In this paper, the cloud model is used to evaluate the emergency capability of subway shield construction. First, based on the emergency work of subway shield construction, this paper constructs an evaluation index system for the emergency capability of subway shield construction, with four first-grade indices and 23 second-grade indices. Second, the subjective and objective combination of the DEMATEL and entropy weight methods are used to determine the index weight. At the same time, a cloud model is introduced to construct a model for the evaluation of the emergency capability of subway shield construction. Finally, a case study is carried out, and the results show that this evaluation model can be used to accurately evaluate the emergency capability of subway shield construction, and can determine its level and obtain the cloud map of the emergency capability of subway shield construction of the enterprise. From the evaluation results, we can find the weak links and existing problems in the emergency capability of subway shield construction, which will help enterprises to take improvement measures. The evaluation results are broadly consistent with the conclusions of the annual work report on enterprise emergency management, verifying the scientificity and effectiveness of the evaluation method.
Function for the limitations of existing analog power, a PID algorithm based on high-precision digital power design. DSP and FPGA technology to do with digital PID regulator, produced by the digital PID algorithm to control the PWM wave chopper to control the main circuit, thereby replacing the traditional analog PID regulator. Experiments show that: a flexible system structure change, according to system requirements, for a variety of digital PID control variable, the circuit is more simple, more accurate, more versatile.
Abstract The Baihetan superhigh arch dam is the largest hydropower station under construction in the world. Columnar jointed basalt (CJB) is widely distributed and densely jointed at the foundation of the Baihetan superhigh arch dam and poses a potential risk to its overall stability. A method of overburden consolidation grouting of the rock mass is proposed that solves the problem of unloading relaxation of CJB due to excavation of the exposed rock mass. The results show the following. 1) The method of nonoverburden grouting cannot achieve the quality inspection standard requirement that at least 90% of the wave velocities be greater than or equal to 4200 m/s, and the overall wave velocity of the rock mass before excavation is greater than that after grouting. 2) After overburden consolidation grouting of the rock mass, which includes controlling grouting pressure and concentration and performing perforation and sequence grouting, the water permeability of the inspection holes is less than 3 Lu, more than 90% of the wave velocities in the rock mass are greater than 4200 m/s, and the integrity of the rock mass is greatly improved. 3) The problems of conventional consolidation grouting technology are solved to protect the thin layer of breccia lava at the foundation of the Baihetan dam. In addition, the problem of unloading relaxation of CJB due to exposure to consolidation grouting is solved in the Baihetan superhigh arch dam project. This application has reference significance for the design and application of consolidation grouting in similar projects.
This article proposes a new discrete-time predictive sliding mode control (DPSMC) for a parallel micropositioning piezostage to improve the motion accuracy in the presence of cross-coupling hysteresis nonlinearities and input constraints. Unlike the traditional linear discrete-time sliding mode control (DSMC), the proposed DPSMC is chattering free and has a faster convergence rate thanks to the design of a nonlinear discrete-time fast integral terminal sliding mode surface. Moreover, by combining with the receding horizon optimization, the sliding mode state is predicted to follow the expected trajectory of a predefined continuous sliding mode reaching law, which also allows the proposed controller to explicitly deal with constraints. The stability of the closed-loop system is analyzed under the model disturbances and constraints, and proves that the proposed DPSMC can offer a smaller quasi-sliding mode bandwidth than the traditional DSMC. The effectiveness of the proposed controller is validated by a series of numerical simulations and experiments. Results demonstrate the advantages of proposed DPSMC over the traditional DSMC method.
Recently, neural implicit representations have been applied in the mapping process of simultaneous localization and mapping (SLAM), accompanied by less storage overhead and continuous representation. Nevertheless, related methods use a single neural network to represent the whole scene, resulting in forgetting the observed regions caused by the limited capacity of a single network in the large-scale scene. Several methods encode the scene into implicit voxels to avoid parameter forgetting while the memory is sacrificed. In this letter, we introduce a scalable mapping framework that utilizes extensible Neural Implicit Spatial Blocks (NISB) with fixed size to cover the entire scene by incrementally creating multiple Multi-Layer Perceptron (MLP) networks. In evaluations against alternative methods on 3 datasets of indoor environments, our method Avoids forgetting the observed areas during the mapping process with a small memory footprint and smoothly updates the global map at 2 Hz.
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