Sensitivity Function Trade-offs for Networks with a String Topology

We present two sensitivity function trade-offs that apply to a class of networks with a string topology. In particular we show that a lower bound on the H-infinity norm and a Bode sensitivity relation hold for an entire family of sensitivity functions associated with growing the network. The trade-offs we identify are a direct consequence of growing the network, and can be used to explain why poorly regulated low frequency behaviours emerge in long vehicle platoons even when using dynamic feedback

Then, There Were Nine: The Forgotten Higher Schools of Imperial Japan

Following the Meiji Restoration of 1868, Japan hurried to modernize all aspects of the new nation-state and prevent colonization by Western powers. As a critical element in that effort, a centralized system of education was created, compulsory schooling instituted, and advanced schools were established. A further development saw, in a single Taisho decade of the 1920s, the birth of nine higher schools of an articulated structure with progressive pedagogical perspective. In the following Showa era, Japan’s defeat in the Second World War resulted in a wide-ranging reshuffling of its education system, first imposed by the victorious Allied Occupation Forces. In that process, with little appreciation of the significance of their venture, all of the unique institutions were summarily abolished in 1950. This article traces the history of the obliterated schools and closely examines the virtues of their educational approach in the light of modern studies from the East and West

Ensuring educational opportunities for children in conflict-affected contexts : A case study of Syrian refugee-managed schools in Turkey

The key actor within the scope of refugee education has been shifting from external agencies to the refugees themselves over time. In recent years, refugees have taken the initiative to fulfill their demands for education. Ninety percent of Syrian refugees residing in Turkey live outside of the refugee camp and some part of them run independent schools in urban areas. However, the actual dynamics of their education are not outwardly reflected in statistics such as school enrollment ratio and remain largely unknown. The objective of this study is to examine the school operation mechanisms managed by Syrian urban refugees. The fieldwork took place in two southern Turkish provinces adjacent to the Syrian border for nine weeks in total during 2013 and 2015. Interviews and participant observations were conducted with Syrian school stakeholders. This study reveals four factors below as characteristics of elements allowing school education by Syrian refugees in Turkey to function: (1) Partial cooperative relationship between the stakeholders of the education for Syrian refugees; (2) Involvement of Turkish governmental organizations and responses by each school; (3) Connections between international/domestic supporters and Syrian schools; and (4) Ensuring diploma certificates and the impact the certificates have on student lives. Currently, it is difficult for unstably managed Syrian schools alone to respond to all the educational demands from Syrian refugees hoping for bridges to higher education. However, it is true that the expansion of education is being facilitated by activities by Syrian refugees themselves

Hypertracking and Hyperrejection: Control of Signals beyond the Nyquist Frequency

This paper studies the problem of signal tracking and disturbance rejection for sampled-data control systems, where the pertinent signals can reside beyond the so-called Nyquist frequency. In light of the sampling theorem, it is generally understood that manipulating signals beyond the Nyquist frequency is either impossible or at least very difficult. On the other hand, such control objectives often arise in practice, and control of such signals is much desired. This paper examines the basic underlying assumptions in the sampling theorem and pertinent sampled-data control schemes, and shows that the limitation above can be removed by assuming a suitable analog signal generator model. Detailed analysis of multirate closed-loop systems, zeros and poles are given, which gives rise to tracking or rejection conditions. Robustness of the new scheme is fully characterized; it is shown that there is a close relationship between tracking/rejection frequencies and the delay length introduced for allowing better performance. Examples are discussed to illustrate the effectiveness of the proposed method here

Algebraic connectivity of layered path graphs under node deletion

This paper studies the relation between node deletion and the algebraic connectivity for a graph with a hierarchical structure represented by layers. The problem is motivated by a mobile robot formation control guided by a leader. In particular, we consider a scenario in which robots may leave the network resulting in the removal of the nodes and the associated edges. We show that the existence of at least one neighbor in the upper layer is crucial for the algebraic connectivity not to deteriorate by node deletion

Scale Free Bounds on the Amplification of Disturbances in Mass Chains

We give a method for designing a mechanical impedance to suppress the propagation of disturbances along a chain of masses. The key feature of our method is that it is scale free. This means that it can be used to give a single, fixed, design, with provable performance guarantees in mass chains of any length. We illustrate the approach by designing a bidirectional control law in a vehicle platoon in a manner that is independent of the number of vehicles in the platoon