The behavior of nonlinear pulsatile flow of incompressible blood contained in an elastic tube is examined. The theory takes into account the nonlinear convective terms of the Navier-Stokes equations. The motion of the arterial wall is characterized by a set of linearized differential equations. The region bounded by the flexible arterial wall is mapped into a fixed area in which numerical discretization takes place. The finite element method (Galerkin weighted residual approach) is used for the solution of this nonlinear system. The results obtained are pressure distribution, velocity profile, flow rate and wall displacements along the elastic tube (20 cm long).
The toggle–brace–damper system (TBDS) is an effective displacement amplification damper occupying a large building space. The small deformation solution, which is widely used, cannot describe the feature that the displacement amplification capacity varies with the lateral displacement of the TBDS. This is not conducive to investigate the performance of the TBDS comprehensively. Therefore, the geometric design and optimization of the TBDS are lack of a theoretical basis. A generalized toggle–brace–damper system (GTBDS), a generalized form of TBDS, is proposed. It has a flexible layout and optimizes the space available. We also introduce an amplification factor of displacement increment (AFDI) that can accurately describe the performance of the GTBDS. The amplification capacity and the geometric sensitivity are two aspects of the performance. The influence of geometric parameters on the performance of the GTBDS is clarified based on the AFDI. Some regulations are also proposed to compare the performance of GTBDSs with different geometric constructions. Two geometric parameter optimization methods of the GTBDS are proposed to balance its amplification capacity, operation safety and geometric sensitivity. The relationship between the displacement amplification capacity and the energy dissipation capacity of the GTBDS is examined. The existing modal energy dissipation method (MEDM) is extended to calculate the additional damping ratio (ADR) provided by the GTBDS. Combining the calculation method of ADR and the geometric optimization methods of GTBDS, a multiperformance objectives design method of the GTBDS is proposed. The case analysis verifies the effectiveness and the feasibility of the design method.
The input-output table is very comprehensive and detailed in describing the national economic systems with abundant economic relationships, which contain supply and demand information among various industrial sectors. The complex network, a theory, and method for measuring the structure of a complex system can depict the structural characteristics of the internal structure of the researched object by measuring the structural indicators of the social and economic systems, revealing the complex relationships between the inner hierarchies and the external economic functions. In this paper, functions of industrial sectors on the global value chain are to be distinguished with bipartite graph theory, and inter-sector competitive relationships are to be extracted through resource allocation process. Furthermore, quantitative analysis indices will be proposed under the perspective of a complex network, which will be used to bring about simulations on the variation tendencies of economies’ status in different situations of commercial intercourses. Finally, a new econophysics analytical framework of international trade is to be established.
Seismic performance assessment of water distribution systems (WDSs) based on hydraulic simulation is essential for resilience evaluation of WDSs under earthquake disasters. The assessment is mainly to determine how the water supply will be affected due to pipe breaks caused by the earthquake, with the water supply loss estimated based on the loss of supply to nodes. Existing research works usually use the average or overall performance metric of all user nodes as the system performance indicator without considering user nodes’ individual performance and criticality. This paper proposes a framework to evaluate the importance of user nodes considering post-earthquake rescue service and the seismic performance of individual user nodes in the WDS, which supports the pipeline renovation plan to improve the performance of critical user nodes. The importance of user nodes is evaluated by a multi-index model, including the indices for daily service, post-earthquake rescue service, and network topology influence of user nodes. These indices evaluate the importance of user nodes in terms of their roles for daily water service, emergent rescue service, and water transmission to other nodes, respectively. Fragility model of pipelines evaluates the earthquake-induced damages of the WDS, and the seismic performance assessment of the WDS system is performed by the hydraulic model of the WDS with pipeline damages. The proposed framework is implemented in an actual WDS; the results show that the importance classification to user nodes by multi-index approach can identify the critical user nodes for post-earthquake rescue service, which traditional methods may ignore. The importance classification and seismic performance of individual user nodes make it feasible to check the seismic performance of critical user nodes and formulate a targeted pipeline renovation plan to focus limited resources on critical user nodes.
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