Ppj Paul van den Bosch

Mathematical modeling confirms the length-dependency of telomere shortening

Telomeres, the ends of chromosomes, shorten with each cell division in human somatic cells, because of the end-replication problem, C-strand processing and oxidative damage. On the other hand, the reverse transcriptase telomerase can add back telomeric repeats at the telomere ends. It has been suggested that once telomeres have reached a critical length, cells cease proliferation, also known as senescence. Evidence is accumulating that telomere shortening and subsequent senescence might play a crucial role in life-threatening diseases. So far, mathematical models described telomere shortening as an autonomous process, where the loss per cell division does not depend on the telomere length itself. In this study, published measurements of telomere distributions in human fibroblasts and human endothelial cells were used to show that telomeres shorten in a length-dependent fashion. Thereafter, a mathematical model of telomere attrition was composed, in which a shortening factor and an autonomous loss were incorporated. It was assumed that the percentage of senescence was related to the percentage of telomeres below a critical length. The model was compared with published data of telomere length and senescence of human endothelial cells using the maximum likelihood method. This enabled the estimation of physiologically important parameters and confirmed the length-dependency of telomere shortening.

Technical Communique: Optimal closed-loop identification test design for internal model control

In this work, optimal closed-loop test design for control is studied. Simple design formulas are derived based on the asymptotic theory of Ljung. The control scheme used is internal model control (IMC) and the design constraint is the power of the process output or that of the reference signal. The test signal is applied at the setpoint. The results give clear guidelines for closed-loop identification applications.

Subspace-based parameter estimation of exponentially damped sinusoids using prior knowledge of frequency and phase

Subspace-based parameter estimators, like HTLS in nuclear magnetic resonance spectroscopy, are efficient and accurate in estimating parameters of a sum of exponentially damped sinusoids. But they suffer from a serious drawback that little prior knowledge can be incorporated which is important for the resolution and accuracy. Recently, one type of prior knowledge, known frequency and damping of some exponentials, has been successfully incorporated into HTLS. In this paper, another type of prior knowledge, known frequency and phase of some exponentials, is incorporated into HTLS. In addition, some variants are derived which allow some combinations of prior knowledge of frequency, damping and phase. The benefit of the new extended HTLS methods is confirmed via a simulation study. The same ideas can be used directly in other subspace-based parameter estimation methods as well.

Fuel reduction potential of energy management for vehicular electric power systems

In the near future a significant increase in electric power consumption in vehicles is to be expected. To limit the associated increase in fuel consumption and exhaust emissions, smart strategies for the generation, storage/retrieval, distribution and consumption of the electric power can be used. This paper considers a vehicle configuration with a conventional drive train. Two energy management strategies that control the alternator power are analysed: a regenerative braking strategy and a more advanced strategy based on optimisation techniques. The potential behind these strategies is analysed by studying the typical characteristics of components that are directly related to the energy flow in the vehicle. It is shown that operating the internal combustion engine at the highest efficiency will not inherently lead to the lowest fuel consumption. Subsequently, engineering rules are presented to evaluate the performance that can be expected for each strategy. The component characteristics are included as input parameters to make the method generally applicable. To show the value of the engineering rules, the potential fuel reduction is computed for a specific vehicle configuration and driving cycle and compared with simulations results.

State fusion with unknown correlation: Ellipsoidal intersection

Some crucial challenges of estimation over sensor networks are reaching consensus on the estimates of different systems in the network and separating the mutual information of two estimates from their exclusive information. Current fusion methods of two estimates tend to bypass the mutual information and directly optimize the fused estimate. Moreover, both the mean and covariance of the fused estimate are fully determined by optimizing the covariance only. In contrast to that, this paper proposes a novel fusion method in which the mutual information results in an additional estimate, which defines a mutual mean and covariance. Both variables are derived from the two initial estimates. The mutual covariance is used to optimize the fused covariance, while the mutual mean optimizes the fused mean. An example of decentralized state estimation, where the proposed fusion method is applied, shows a reduction in estimation error compared to the existing alternatives.

Non-linear full-car modeling and sky-hook control for a direct-drive active suspension system

At Eindhoven University of Technology an active suspension system has been developed [1]. This system is superior to other active suspension in terms of bandwidth and power consumption. This active suspension system was tested on a quarter car setup and showed improvements of up to 48% in comfort [2]. In order to implement this suspension in a test vehicle with the same improvements, a non-linear full-car model is developed in this paper which is used to simulate and design various controllers. The non-linear model incorporates non-linear damping, bump stops, actuator saturation and actuator friction. To model the friction in the actuator a combination of Coulomb and viscous friction is used. To model the MacPherson suspension strut, two methods are described and compared. Also the implications of using acceleration sensors which are placed in line with the MacPherson strut are discussed. It is shown that the placement of the acceleration sensors limits the control performance during vehicle acceleration and cornering

Modeling and Identification of a 3-DOF Planar Actuator with Manipulator

The goal of this paper is to describe the identification and modeling of a 3-degree-of-freedom (DOF) platform with a manipulator on top of it, which is magnetically levitated by 9 voice-coil actuators. This 3-DOF experimental setup is a pre-prototype of a 6-DOF magnetically levitated platform with manipulator in order to study combined control of both the platform and manipulator.

Criteria for demand response systems

The topic of demand side management is currently becoming more important than ever, in parallel with the further deregulation of the electricity sector, and the increasing integration of renewable energy sources. A historical review of automation integration in power system control assists in identifying established operational rules of contemporary systems, which subsequently evoke fundamental requirements for demand response applications. The scope of this paper is to provide a set of infrastructural, architectural and operational criteria for demand response systems, to support the process of establishing standards and procedures. An effort is made to address the views of system and market operators, deregulated utilities, ancillary service providers and customers.

Infrared wireless data transfer for real-time motion control

Abstract In this paper several wireless solution are compared for their suitability for real-time control of a fast motion system. From the comparison, Very Fast Infrared (VFIR) communication link has been found to be an attractive solution for presented wirelessly controlled manipulator. Because standard VFIR even does no meet demands on minimal delay, a new infrared (IR) wireless link has been developed based on modification of VFIR standard. Presented IR wireless link can transmit 64 data bits from input port of the transmitter to the output port of the receiver in less than 7 microseconds. This time was achieved by custom packet and data processing. Such a delay makes the wireless link indistinguishable from a wired link up to sampling frequency of a few kHz. Several tests are presented which prove the delay and the maximal reliable range of about 0.7 m with CRC error rate better than 10 −7 .

Adaptive control strategies for productive toner printers

This chapter discusses design considerations for industrial systems and processes when embedded systems allow to intelligently influence the system in real-time. It is shown that in such embedded systems the capability to adapt themselves to changing environments and/or to different operating conditions has to be exploited. If properly done, almost all performance indicators like accuracy, speed, robustness, insensitivity for disturbances, will improve. The challenge is to first study the process for which the behaviour has to be improved. Based on the characteristics of the process and its disturbances, one wishes to select among the hundreds of tools to achieve its goals. For the professional printer, this design process and its many compromises and choices will be illustrated. Consequently, the professional printer will be analysed for its specific characteristics whose behaviour can be influenced during printing. Based on these characteristics, appropriate control approaches are discussed in more detail to show how control can cope with uncertainty or changing parameters. With extensive and illustrative examples the various methods are compared and it is shown why some control approaches are preferred solutions in the large number of problems that are faced by professional printers.