TS fuzzy robust L1 control for nonlinear systems with persistent bounded disturbances

In this paper, a novel technique for Takagi–Sugeno (TS) model-based robust L₁ controller design of nonlinear systems is proposed. Two synthesis methods based on quadratic and non-quadratic Lyapunov functions are considered. To design the robust stabilizing controller, a new approach for deriving sufficient conditions associated with the L₁ performance criterion in terms of strict linear matrix inequality is proposed. This novel technique results in less pre-chosen scalar design variables and calculation burden. Furthermore, deriving the controller synthesis conditions via a non-quadratic Lyapunov function (NQLF) relaxes the obtained conditions. Therefore, the proposed approaches not only efficiently minimize the effect of persistent bounded disturbance, but also are applicable for wider classes of TS systems. Furthermore, some new lemmas are proposed to facilitate strict LMI formulation and to provide more degrees of freedom. Finally, several numerical and practical examples are presented to show the merits of this paper.     

Startups by recent university graduates and their faculty: Implications for university entrepreneurship policy

Earlier research on the role of universities in fostering entrepreneurial economic development almost exclusively covers spin-offs by faculty and staff. In contrast, we provide general evidence from the U.S. showing that the gross flow of start-ups by recently graduated students with an undergraduate degree in science or engineering is at least an order of magnitude larger than the spin-offs by their faculty, that a recent graduate is twice as likely as her Professor to start a business within three years of graduation, and that the graduates’ spin-offs are not of low quality. Three case studies illustrate how universities may stimulate science and engineering students and recent graduates to create new firms of high quality. We conclude that transforming university goals and practices toward increasing start-ups led by faculty might not be the most effective way for universities to stimulate entrepreneurial economic development.     

Microfluidic conformal coating of non-spherical magnetic particles

We present the conformal coating of non-spherical magnetic particles in a co-laminar flow microfluidic system. Whereas in the previous reports spherical particles had been coated with thin films that formed spheres around the particles; in this article, we show the coating of non-spherical particles with coating layers that are approximately uniform in thickness. The novelty of our work is that while liquid-liquid interfacial tension tends to minimize the surface area of interfaces—for example, to form spherical droplets that encapsulate spherical particles—in our experiments, the thin film that coats non-spherical particles has a non-minimal interfacial area. We first make bullet-shaped magnetic microparticles using a stop-flow lithography method that was previously demonstrated. We then suspend the bullet-shaped microparticles in an aqueous solution and flow the particle suspension with a co-flow of a non-aqueous mixture. A magnetic field gradient from a permanent magnet pulls the microparticles in the transverse direction to the fluid flow, until the particles reach the interface between the immiscible fluids. We observe that upon crossing the oil-water interface, the microparticles become coated by a thin film of the aqueous fluid. When we increase the two-fluid interfacial tension by reducing surfactant concentration, we observe that the particles become trapped at the interface, and we use this observation to extract an approximate magnetic susceptibility of the manufactured non-spherical microparticles. Finally, using fluorescence imaging, we confirm the uniformity of the thin film coating along the entire curved surface of the bullet-shaped particles. To the best of our knowledge, this is the first demonstration of conformal coating of non-spherical particles using microfluidics.     

Aging and social security system in Pakistan: policy challenges,opportunities, and role of China–Pakistan Economic Corridor (CPEC)

ABSTRACT

The purpose of this research is to highlight the aging and elderly care in Pakistan, a country considered the seventh most populous country in the world with an estimated population of 220 million people (citation, 2017). In 2013, Pakistan signed a MoU with China for 56 billion in US$ to create opportunities for the youngsters, but there was no story of opportunity included for the senior citizens. An attempt has been made to raise awareness of the plight of seniors to the Pakistan Government’s attention; however since there is no formal policy dedicated to elders from the Chinese mega MoU and political instability, only little has been accomplished to better the lives of older adults. Modernization has had a major impact on the life of older Pakistani, and not always a positive effect. This research focuses on the important issues that are making the lives of senior citizens more difficult. The issues include psychological factors, anxiety, physical issues, and environmental issues. The research concludes while many factors are making the lives of senior citizens problematic, seniors are still living a satisfied life because they are not depending on their children or others. Senior citizens demand and desire time with their children and grandchildren. Increases found in elders’ psychological problems are likely correlated with modernization. Unfortunately, the China–Pakistan Economic Corridor (CPEC) and the mega project remain totally for the younger population with no economic prospects for elders to directly benefit. Thus, the question remains what will be the outcome for Pakistani seniors?     

Simulation of gait asymmetry and energy transfer efficiency between unilateral and bilateral amputees

Efficient walking or running requires symmetrical gait. Gait symmetry is one of the key factors in efficient human dynamics, kinematics and kinetics. The desire of individuals with a lower-limb amputation to participate in sports has resulted in the development of energy-storing-and-returning (ESR) feet. This paper analyses a case study to show the effect of symmetry and asymmetry as well as energy transfer efficiency during periodic jumping between simulated bilateral and unilateral runners. A custom gait analysis system is developed as part of this project to track the motion of the body of a physically active subject during a set of predefined motions. Stance and aerial times are accurately measured using a high speed camera. Gait frequency, the level of symmetry and the non-uniform displacement between left and right foot and their effects on the position of the Centre of Mass (CM) were used as criteria to calculate both peak energies and transformation efficiency. Gait asymmetry and discrepancy of energy transfer efficiency between the intact foot and the ESR are observed. It is concluded that unilateral runners require excessive effort to compensate for lack of symmetry as well as asymmetry in energy transfer, causing fatigue which could be a reason why bilateral amputee runners using ESR feet have a superior advantage over unilateral amputees.