Dynamic Response of Bridge-Landslide Parallel System under Earthquake

In order to further understand the instability mechanism and geohazard causation when the main sliding path of the slope body is parallel to the path of the bridge, the corresponding bridge-landslide parallel system is constructed for shaking table tests. This paper summarizes the combination forms of bridge-landslide model under different position and focused on the slope body located above the bridge deck. Firstly, based on the shaking table test results of El Centro (1940), the failure behavior of bridge-landslide parallel system was evaluated, and the changes of acceleration and deformation of bridge pile were subsequently analyzed. Then, the interaction bridge structure and sliding body were explained by the spectral features. The main conclusions are as follows. First, in the model test, the landslide belongs to the thrust-type landslide. Due to the barrier function of the bridge, the main failure site of landslide occurs in the middle and trailing edge of slope body. At the same time, the acceleration value of earthquake waves is 0.3 g, which is the key to this variation. Second, the acceleration response of the measuring points on the bridge pile and landslide increases with the increase of ground elevation. If the slope structure is damaged severely, the deformation response of weak interlayer is inconsistent with the surrounding soil structure. Third, with the increase of excitation power, the dominant frequency of bridge-landslide parallel system gradually transitions from low to high frequency rate, and the interaction of the parallel system weakens the influence of river direction on frequency. Finally, under the same working condition, the dynamic response of the measuring points has obvious regularity with the change of situation. But the response of the same points is not regular due to the different earthquake excitation intensity.

Power Sharing Control Strategy of High-Frequency Chain Matrix Converter Parallel System Based on Adaptive Virtual Impedance

In the high frequency link matrix converter parallel system, the impedance parameters on each line are unequal so that the output power of each converter is not equal. To solve this problem, the reason why the power cannot be divided equally under the droop control strategy is analyzed, and a power sharing strategy based on adaptive virtual impedance is proposed. This strategy introduces virtual impedance in a voltage-current dual-loop system with droop control, and uses the converter’s power information and output power factor to adaptively adjust the amplitude and phase of the virtual impedance, so that different branches have the same equivalent output impedance to compensate The voltage drop on the line impedance, while adding the droop control fine-tuning compensation link, so as to realize the load power sharing. Simulation results show that the proposed strategy can effectively improve the accuracy of output power sharing and ensure the stability of the system output voltage amplitude.

Education, Citizenship, and National Identity in the Sahel

At independence, Sahelian states inherited educational systems rooted in the colonial French model and based on secularism or laïcité. Both during and after colonialism, these formal public educational systems found little popular appeal, and indeed often faced clear resistance at the popular level. By contrast, a parallel system of Islamic education thrived, expanded, and evolved in the region, ranging from traditional Quranic schools to more modern Franco-Arabic schools. In the 1990s, a number of factors began to call into question the viability of this bifurcated educational system. This chapter surveys the trajectory of educational systems in the Muslim societies of the Sahel, and analyzes the forces shaping new hybrid models that are emerging. It examines how reformed educational systems are evolving in ways that diverge from the historical secular model with the potential for producing new models of citizenship deeply imbued with religious identities. The chapter offers an interpretation of the longer-term implications of these changes for national identity and citizenship in a changing Sahel.

Bi-Objective Reliability-Cost Interactive Optimization Model for Series-Parallel System

The paper aims are to determine the bi-objective reliability-cost problem of a series-parallel system by employing an interactive approach. Multi-objective optimization is a design methodology that optimizes a combination of objective functions orderly and concurrently. The fuzzy membership functions have been designated to settle the contrary nature of the objectives. Based on these functions and the moment of the objectives in the form of the weight vector, a crisp optimization design is formed. Lastly, the inherited problem is determined with the aid of the PSO (Particle Swarm Optimization) algorithm and confronted with the genetic algorithm. The solution resembling the various choices of the decision-makers towards the evaluation of their decision are listed. A decision-maker can pick an immeasurable one according to his requirement to reach at the aspired goal.

A multi-objective selective maintenance optimization method for series-parallel systems using NSGA-III and NSGA-II evolutionary algorithms

Aiming at the problem that the downtime is simply assumed to be constant and the limited resources are not considered in the current selective maintenance of the series-parallel system, a three-objective selective maintenance model for the series-parallel system is established to minimize the maintenance cost, maximize the probability of completing the next task and minimize the downtime. The maintenance decision-making model and personnel allocation model are combined to make decisions on the optimal length of each equipment’s rest period, the equipment to be maintained during the rest period and the maintenance level. For the multi-objective model established, the NSGA-III algorithm is designed to solve the model. Comparing with the NSGA-II algorithm that only considers the first two objectives, it is verified that the designed multi-objective model can effectively reduce the downtime of the system.