Ali Fuat Ergenc

Extended Kronecker Summation for Cluster Treatment of LTI Systems with Multiple Delays

A new procedure is presented for determining the kernel and the offspring hypersurfaces for general linear time invariant (LTI) dynamics with multiple delays. These hypersurfaces, as they have very recently been introduced in a concept paper [R. Sipahi and N. Olgac, Automatica, 41 (2005), pp. 1413-1422], form the basis of the overriding paradigm which is called the cluster treatment of characteristic roots (CTCR). In fact, these two sets of hypersurfaces exhaustively represent the locations in the domain of the delays where the system possesses at least one pair of imaginary characteristic roots. To determine the kernel and offspring we use the extraordinary features of the “extended Kronecker summation” operation in this paper. The end result is that the infinite-dimensional problem reduces to a finite-dimensional one (and preferably into an eigenvalue problem). Following the procedure described in this paper, we are able to shorten the computational time considerably in determining these hypersurfaces. We demonstrate these concepts via some example case studies. One of the examples treats a 3-delay system. For this case another interesting perspective, called the “building block,” is also utilized to display the kernel in three-dimensional space in the domain of “spectral delays.”

“Delay Scheduling”: A New Concept for Stabilization in Multiple Delay Systems

A trajectory-tracking problem is considered for a linear time invariant (LTI) dynamics with a fixed control law. However, the feedback line is affected by multiple time delays. The stability of the dynamics becomes a complex problem. It is well known that time-delayed LTI systems may exhibit multiple stable operating zones (which we call pockets) in the space of the delays. Our aim in this paper is to locate and experimentally validate these pockets. For the analytical determination of the pockets we utilize a new methodology, the cluster treatment of characteristic roots (CTCR). The study results in several interesting conclusions. (i) The systems may exhibit better control performance (for instance, faster disturbance rejection) for larger time delays. (ii) Consequently, we propose a unique and interesting utilization of the time delays as agents to enhance the control performance, the delay scheduling technique.

Rotationally oscillating drill (Ros-Drill©) for mouse icsi without using mercury

Intracytxoplasmic sperm injection (ICSI) is an important assisted reproductive technology (ART). Due to deployment difficulties and low efficiency of the earlier (conventional) version of ICSI, especially in the mouse, a piezo‐assisted ICSI technique had evolved as a popular ART methodology in recent years. An important and remaining problem with this technique, however, is that it requires small amounts of mercury to stabilize the pipette tip when piezoelectric force pulses are applied. To eliminate this problem we developed and tested a completely different and mercury‐free technology, called the “Ros‐Drill©” (rotationally oscillating drill). The technique uses microprocessor‐controlled rotational oscillations on a spiked micropipette without mercury or piezo. Preliminary experimental results show that this new microinjection technology gives high survival rate (>70% of the injected oocytes) and fertilization rate (>80% of the survived oocytes), and blastocyst formation rates in early trials (∼50% of the survived oocytes). Blastocysts created by Ros‐Drill© ICSI were transferred into the uteruses of pseudopregnant surrogate mothers and healthy pups were born and weaned. The Ros‐Drill© ICSI technique is automated and therefore; it requires a very short preliminary training for the specialists, as evidenced in many successful biological trials. These advantages of Ros‐Drill© ICSI over conventional and piezo‐assisted ICSI are clearly demonstrated and it appears to have resolved an important problem in reproductive biology. Mol. Reprod. Dev. 75: 1744–1751, 2008.

EXTENDED KRONECKER SUMMATION FOR DETERMINING THE KERNEL AND OFFSPRING OF LTI SYSTEMS WITH MULTIPLE DELAYS

Abstract A new concept is presented for determining the kernel and the offspring hypersurfaces for general LTI dynamics with multiple delays. These hypersurfaces, as they are very recently introduced in a concept paper (Sipahi and Olgac 2005), form the basis of the overriding paradigm which is called the “Cluster Treatment of Characteristic Roots (CTCR)”. In fact, these two sets of hypersurfaces exhaustively represent the locations in the domain of the delays where the system possesses at least one pair of imaginary characteristic roots. To determine these kernel and offspring we use the extraordinary features of “Extended Kronecker Summation” operation in this paper. The end result is that the infinite dimensional problem reduces to a finite dimensional one (and preferably into an eigenvalue problem). Following the procedure described in this paper we are able to shorten the computational time considerably in determining these hypersurfaces. We demonstrate these concepts via some example case studies.

Sign Inverting Control logic for time delayed systems, with experiments

A new control strategy is introduced in this paper for Linear Time Invariant (LTI) systems with a single time delay. Earlier research findings on this class of systems reveal the delay intervals for stable operation, exhaustively, exactly and completely. The newly developed Sign Inverting Control (SIC) logic suggests a very practical procedure of reversing the sign of the feedback control gain, in order to argument the stable delay intervals. The sign reversal concept is based on some interesting mathematical features of LTI-Time Delay Systems (LTI-TDS) which were first recognised under a recent paradigm called the Cluster Treatment of Characteristic Roots (CTCR). Example case studies as well as the experimental trials demonstrate the practicality and the advantages of the new logic, Sign Inverting Control law.

Design of a Hardware and Software based Test Bed for Railway Signalization Systems

Abstract It is vital that an interlocking system is thoroughly tested before its deployment. The conduction of the tests of an interlocking system on the real field is cumbersome and expensive. It is necessary that fast and efficient methods are utilized to test the hardware and the software of interlocking systems before its final installation. In this manuscript, the design of hardware and software based test beds for a railway signalization system is presented.

Use of non-identical multiple delayed resonators in active suspension systems of railway vehicles

In this study, an active suspension system with multiple non-identical delayed resonators (DR) is proposed in order to, suppress vibrations that are caused by railway track irregularities. Mathematical models for a railway vehicle and track irregularities are given. In addition to this, methods on choosing the physical parameters and the design steps of multiple DR are mentioned. Simulations using the approximate mechanical parameters of a Shinkansen SKS300 train are made. Results and comparison with other methods are also given to evaluate the success of the proposed method.

An Experimental Study for Delay-Independent State-Feedback Controller Design

Abstract In this study, a method for determining delay-independent stability zones of the general LTI dynamics with multiple delays against parametric uncertainties is presented. The method is utilized to design a delay-independent state-feedback controller and verified experimentally for a two-tank liquid level control system. The method is based on extended kronecker summation(EKS) to investigate controller parameter space for delay-independent stability(DIS) of the system. The main aim of the paper is recalling a new sufficient condition for determination of controller parameter space for DIS and presenting the application of methodology for a physical experimental case study.

A Matrix Technique for Dominant Pole Placement of Discrete-Time Time-Delayed Systems

Abstract A matrix method is introduced for determination of robust-stability zones of the general linear time invariant discrete-time dynamics with large delays against parametric uncertainties. The technique employs Kronecker Product and unique properties of palindrome polynomials. These polynomials are subset of self-inversive polynomials which exert advantageous tools for examination of the distribution of its zeros. The main motivation in this paper is to develop a practical tool for determination of robust stability zones against parametric uncertainties and dominant pole assignment in discrete-time domain. A sufficient condition for robust stability and dominant pole assignment is presented. The procedure for the solution is demonstrated via some example case studies.

On the Geometric Characteristics of Cell Membrane Using Rotationally Oscillating Drill (Ros-Drill©)

ICSI (intracytoplasmic sperm injection) is a broadly utilized assisted reproductive technology. A number of new versions of the procedure have evolved lately, such as piezo-assisted ICSI technique. An important problem with this technique, however, is that it requires small amounts of mercury to stabilize the pipette tip. A completely different and mercury-free technology, called the “Ros-Drill©” (rotationally oscillating drill) was developed by the group of the authors. It uses microprocessor-controlled rotational oscillations of a spiked micropipette for piercing. One of the key issues is to determine when to start the oscillations. It is based on the cell deformation prior to the membrane piercing. In-situ measurements are needed for this protocol. The contribution of this paper is the utilization of computer vision for these measurements. The triggering logic is correlated to the cell membrane curvature variations along the vision-detected membrane line segment. Such a tool becomes very helpful for automating the Ros-Drill operation.Copyright