Evolution in economics has been treated mainly as a theoretical journey. The methodological difficulties reside in strict assumptions in order to maintain a tractable model for firm dynamics. Agent-Based Computational modeling could be an important breakthrough for evolutionary applications. However, these models rely on deep interpretations of the complete data. In this study, in depth analysis of Turkish firm level data has been presented with an evolutionary point of view using the method of density estimations. The comprehensiveness of the data is unique to the literature. For modeling purposes, Turkish firms could be seen as representing their birth era. The stagnant nature of firms could also be considered as linked to the lack of managerial delegation in underdeveloped economies.

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In this chapter, small and medium enterprises in Turkey have been analyzed in a timely manner to provide insight into their post-COVID-19 performance. The analysis starts with a snapshot of the firm structure and firm size distribution in Turkey. A brief overview of the course of the COVID-19 pandemic in Turkey has been provided. The policy responses to the economic effects of the health crisis have been discussed. SMEs' medium-term dynamics have been tabulated using the data of opening and closing firms during the first months of the pandemic. Several surveys conducted with SMEs during the pandemic by public and private organizations have been combined to match the business owners' expectations to policy responses. To assess the public response to the shock and the solutions, the stock market performance of SMEs has been compared with large firms using stock market indices of XKOBI, XPGIP, and XU100.

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Objective: Hybrid cardiovascular mock circuits (HMC), designed for dynamic testing of Ventricular Assist Devices (VAD), offer physiologic accuracy by sequestering model complexity in silico and ease of construction by reducing number of model elements in vitro. Despite superior response time and precision, pneumatic actuation is avoided in HMCs due to nonlinear dynamics and noise. We tested the hypothesis that a HMC consisting of a variable elastance-driven numerical circuit coupled to a pneumo-hydraulic physical circuit can be controlled without linearizing system dynamics. Methods: Reference left ventricular and aortic pressures generated in silico were tracked, respectively, in in vitro preload and afterload reservoirs by controlling non-linear pneumatic dynamics using the Lyapunov stability criterion. A centrifugal pump, the speed (i.e. flow) of which was adjusted using PID control, was interposed between the reservoirs and mimicked the VAD under evaluation. The flow of a recirculating gear pump was controlled by the backstepping method to equalize reservoir fluid volumes by rejecting pressure and flow disturbances. Sensor noise was reduced with discrete-time Kalman filtering. Results: Our results showed that normal, failing and assisted cardiovascular physiologies were numerically simulated and tracked at physical VAD terminals with high accuracy. Reservoir volumes remained stable at various combinations of heart rate, pressure, and VAD flow. Conclusion: The HMC described here offers a stable performance testing platform for VAD prototypes. Significance: This is the first proof that hybrid systems using pneumatic actuation at hydraulic interfaces can optimally be regulated with nonlinear controllers to achieve precise reference tracking and robust disturbance rejection.