The large-scale coverage of natural gas makes the composition structure and operation mode of natural gas network more complex, higher requirements are put forward for the effectiveness and accuracy of state estimation. The existing methods for state estimation of natural gas network with noise are all modeled after processing the data with noise, leading to the real data being distorted to a certain extent. With that in mind, a data-driven method is presented in this paper. While solving the problem of state estimation for natural gas network with measurement noise in the input data, filtering and denoising are unnecessary during state estimation, retaining the complete information of real data. It avoids destruction of real data induced by separating noise from measured data owing to different methods and intensities of noise processing. According to the gas flow characteristic equation of natural gas system, the original problem is converted into a weighted low-rank approximation problem, the search space is shrunk to an orthogonal complement space. The selection of initial values is not merely unrestricted but there will be no accumulation and transmission of iteration error. The effectiveness of the proposed method is demonstrated through simulating 10-node natural gas network. Compared with the Newton's method, the data-driven method has superior performance, the RMSE achieves 0.2268 and the MAPE achieves 1.63%.INDEX TERMS Data-driven, natural gas network, measurement noise.

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Considering Taiwan’s mountainous terrain and winding roads, the special-shaped arch bridge may exhibit superior adaptability; therefore, it has a wide range of applications in the domestic construction of bridges. This paper describes the basic theory and analytical process of the special-shaped arch bridge, using case studies to illustrate the static response of the bridge under uniform dead load. Furthermore, this paper discusses the effects of the changes of the bridge’s geometric shape from the static load response. The results show that because the arrangement of the special-shaped arch bridge is distinct from that of the traditional arch bridge, the distributions of the initial and completion cable forces are complex such that obtaining regular stress responses is difficult regardless of whether the bridge is in-plane or out-of-plane. Hence, the arrangement of cable forces should be specifically considered when building an analytic model of a special-shaped arch bridge.

As the coupling relationship between a natural gas system and electricity system deepens, the gas generator set will cause the fluctuation of natural gas systems while meeting the variation in demand of the electricity system. In order to quantify the impact of gas demand uncertainty for gas the generator set on the natural gas systems, an equivalent dynamic natural gas network model is presented in this paper. By introducing the concept of electrical analogy, the natural gas transmission equation is established, so that the gas flow in each pipeline is coupled to be calculated simultaneously. The disturbance factor of a gas demand change in an electrical system is introduced into dynamic modeling of gas networks, and the equivalent dynamic natural gas network model is developed. The proposed model effectively expresses the explicit dynamic response relationship between the pressure at a node and the gas demand of gas-fired generators in the form of an analytical formula, which can sufficiently reflect the dynamic performance of a natural gas system under disturbance of the electricity system with the action of electricity–gas coupling, laying the foundation for dynamic analysis of the electricity–gas system. Case studies on a 5-node natural gas network and the integrated electricity–gas system consisting of a 10-node natural gas network and IEEE 14-bus system indicate that the equivalent dynamic model is capable of effectively describing the dynamic response relationship.