Internal Delay Research Articles

English

Modern DSP systems are often well suited to VLSI implementation. Indeed, they are often technically feasible or economically viable only if implemented using VLSI technologies.. The paper is focused on the design of an efficient VLSI architecture for FIR filters which aims at reducing the power consumption and also to reduce the hardware complexity. In the existing method, design of folded FIR filter based on conventional multiplier is presented. It does not allow the internal pipelining delays to be exploited. It leads to significant increase in hardware as well as considerable increase in power consumption. It leads to less throughput and increases hardware complexity. In the proposed method, design of folded finite-impulse response (FIR) filters based on pipelined carry-save multiplier is presented . The design is considered at the bit-level and the internal delays of the pipelined multiplier array are fully exploited in order to reduce hardware complexity. Partially folded architectures are also proposed which are implemented by cascading a number of folded FIR filters. The proposed schemes are compared as to the aspect of hardware complexity with a straightforward implementation of a folded FIR filter based on the conventional multipier . The comparison reveals that the proposed schemes may require 20%–30% less hardware. Due to the lesser carry propagation, the proposed method can achieve low power consumption and higher computational speed strategy.

A Field-Programmable Gate Array (FPGA) TDC for the Fermilab SeaQuest (E906) Experiment and Its Test with a Novel External Wave Union Launcher

We developed a field-programmable gate array (FPGA) TDC module for the tracking detectors of the Fermilab SeaQuest (E906) experiment, including drift chambers, proportional tubes, and hodoscopes. This 64-channel TDC module had a 6U VMEbus form factor and was equipped with a low-power, radiation-hardened Microsemi ProASIC3 Flash-based FPGA. The design of the new FPGA firmware (Run2-TDC) aimed to reduce the data volume and data acquisition (DAQ) deadtime. The firmware digitized multiple input hits of both polarities while allowing users to turn on a multiple-hit elimination logic to remove after-pulses in the wire chambers and proportional tubes. A scaler was implemented in the firmware to allow for recording the number of hits in each channel. The TDC resolution was determined by an internal cell delay of 450 ps. A measurement precision of 200 ps was achieved. We used five kinds of tests to ensure the qualification of 93 TDCs in mass production. We utilized the external wave union launcher in our test to improve the TDC's measurement precision and also to illustrate how to construct the Wave Union TDC using an existing multi-hit TDC without modifying its firmware. Measurement precision was improved by a factor of about two (108 ps) based on the four-edge wave union. Better measurement precision (69 ps) was achieved by combining the approaches of Wave Union TDC and multiple-channel ganging.

A 1.33 μW 8.02-ENOB 100 kS/s successive approximation ADC with supply reduction technique for implantable retinal prosthesis.

This paper presents a chip level 9 bits Charge Folding Successive-Approximation-Register (SAR) Analog-to-Digital Converter (ADC) to be used in a CMOS image sensor for retinal prosthesis. It has a maximum single-ended input range of 1.8 V but only uses a supply voltage of 0.9 V for the entire ADC through the Charge Folding method. Therefore, the input range is no longer limited by the supply rail as in conventional SAR ADC. Moreover, the ADC is controlled by an internal delay line based Asynchronous Clock Generator which can be programmed to adjust the resolution of the ADC from 5 to 9 bits. Therefore, resolution adaptation function can be applied to improve the energy efficiency up to 15%. The test chip is implemented in 0.18 μm CMOS process and occupies an area of 0.15 mm(2). At 0.9 V and 100 kS/s, the 9 bit s ADC consumes 1.33 μW and achieves an energy efficiency of 51.3 fJ/conversion-step . In addition, the power consumption can be further reduced by scaling the supply voltage and sampling frequency. At 100 kS/s, this ADC is capable of converting the input signal at a rate equivalent to 30 frames/s for a pixel array up to 3200 pixels.

Interplay between internal delays and coherent oscillations in delayed coupled noisy excitable systems

Numerical study of variations in coherence of spike trains produced by two stochastically perturbed FitzHugh–Nagumo excitable systems with internal and coupling time-delays is performed. Both, the internal time-delay and the interaction time-delay in some domains of values can substantially increase the coherence but the interplay of the two delays can also lead to quite incoherent spike trains. Numerically observed dependence of the coherence on the delays is qualitatively explained by considering the bifurcations in the system caused by the variations of the values of the internal and the interaction time-lags.

Device-Based Asynchronous Ranging and Node Identification for Wireless Sensor Networks

A fundamental problem when locating sensors in a network is to reliably estimate the distance between pairs of sensors. Since security of sensor networks is vulnerable in the wireless environment, this paper proposes a device-based ranging and node identification scheme, which can be applied to provide secure position information for wireless sensor applications. By generalizing the asynchronous distance estimation technology (distance estimation via asynchronous clocks), a device-based distributed distance estimation method is presented. Moreover, based on the physical property of a device, the communication delay (e.g., internal component delay, difference of the clocks, and response delay) between two wireless sensors may be used to identify the normal wireless sensors, to renew the network node information, and to enhance the reliability of distance estimation. The proposed device-based asynchronous ranging and node identification algorithm is shown to be feasible for identifying malicious sensor nodes in the network and is superior to the delay attack-resilient clock synchronization scheme with regard to the successful detection rate of antinodes and ranging accuracy.

The Application of Cascade Control Based on DMC in Stripping Section Temperature Control System

Predictive control is one of the robust control algorithms that suitable for computerized implementation, and requests lower accuracy of the model. It has been widely used in process control recently. Considering the features of distillation column stripping section, such as complex internal mechanism, time-varying parameters and large time delay, the DMC-PID cascade control strategy is adopted. The simulation results show that this strategy combined the advantages of predictive control and cascade control, can make distillation column stripping section have good dynamic and static characteristic in the presence of external disturbance and time delay. The performances are better than DMC and conventional PID control.

Coverage Optimization and Power Reduction in SFN Using Simulated Annealing

An approach that predicts the propagation, models the terrestrial receivers and optimizes the performance of single frequency networks (SFN) for digital video broadcasting in terms of the final coverage achieved over any geographical region, enhancing the most populated areas, is proposed in this paper. The effective coverage improvement and thus, the self-interference reduction in the SFN is accomplished by optimizing the internal static delays, sector antenna gain, and both azimuth and elevation orientation for every transmitter within the network using the heuristic simulated annealing (SA) algorithm. Decimation and elevation filtering techniques have been considered and applied to reduce the computational cost of the SA-based approach, including results that demonstrate the improvements achieved. Further representative results for two SFN in different scenarios considering the effect on the final coverage of optimizing any of the transmitter parameters previously outlined or a combination of some of them are reported and discussed in order to show both, the performance of the method and how increasing gradually the complexity of the model for the transmitters leads to more realistic and accurate results.

Pinning synchronization of hybrid-coupled directed delayed dynamical network via intermittent control.

This paper concerns the problem of exponential synchronization for a class of general delayed dynamical networks with hybrid coupling via pinning periodically intermittent control. Both the internal delay and coupling delay are taken into account in the network model. Meanwhile, the transmission delay and self-feedback delay are involved in the delayed coupling term. By establishing a new differential inequality, several simple and useful exponential synchronization criteria are derived analytically. It is shown that the controlled synchronization state can vary in comparison with the conventional synchronized solution, and the degree of the node and the inner delayed coupling matrix play important roles in the controlled synchronization state. By choosing different inner delayed coupling matrices and the degrees of the node, different controlled synchronization states can be obtained. Furthermore, the detail pinning schemes deciding what nodes should be chosen as pinned candidates and how many nodes are needed to be pinned for a fixed coupling strength are provided. The simple procedures illuminating how to design suitable intermittent controllers in real application are also given. Numerical simulations, including an undirected scale-free network and a directed small-world network, are finally presented to demonstrate the effectiveness of the theoretical results.

Output-feedback sampled-data control design for linear parameter-varying systems with delay

In this paper, we address the sampled-data output-feedback control design problem for continuous-time linear parameter-varying systems with time-varying delay in the system states. Due to the combination of the plant's continuous-time dynamics and the controller's discrete-time dynamics connected through A/D and D/A converter devices, the closed-loop system is a hybrid system. In order to analyse this hybrid system from stability and performance perspectives we use the input-delay approach to map the closed-loop system into the continuous-time domain with delay in the states. This results in a closed-loop system containing two types of delays, the system internal delay and the one imposed by the mapping. Next, we use delay-dependent conditions for analysis of stability and -norm performance which result in a sampled-data control synthesis procedure. The proposed output-feedback sampled-data controller is obtained based on the solution to a linear matrix inequality optimisation problem using a set of appropriately defined slack variables. A numerical example of a milling machine is presented to demonstrate the viability of the proposed sampled-data control design method to satisfy the stability and performance objectives even with a varying sampling rate.

Validation of an active transponder for KOMPSAT-5 SAR image calibration

This paper describes the development and validation of a transportable active transponder designed for the image calibration of Korea Multi-Purpose Satellite-5 (KOMPSAT-5) with a synthetic aperture radar (SAR). Ground targets are essential in SAR image calibration. The environment for the deployment of ground targets for SAR image calibration should provide uniformity and minimum interference. The Amazon or deserts are regarded as desirable environments. However, such environments for SAR image calibration are difficult to find in Korea. Thus, it will be advantageous to have an active transponder whose performance will not be severely limited by the absence of such uniform environment. We have therefore developed an active transponder which has an adjustable internal delay and into which the orbit data of an arbitrary satellite can be loaded. The stored obit data with the aid of an internal global positioning system (GPS) receiver and gyroscope enables the active transponder to point to a selected satellite. In addition, a virtual deployment of the active transponder is possible due to its adjustable internal delay. Thus, the developed active transponder can be deployed at any place without environmental constraint. The performance of the developed active transponder is validated using the satellite TerraSAR-X, which is already in operation. The test results show that the active transponder is successfully compliant with the requirements for KOMPSAT-5 image calibration.

Calibration and Validation of Airborne InSAR Geometric Model

The image registration or geo-coding is a very important step for many applications of airborne interferometric Synthetic Aperture Radar (InSAR), especially for those involving Digital Surface Model (DSM) generation, which requires an accurate knowledge of the geometry of the InSAR system. While the trajectory and attitude instabilities of the aircraft introduce severe distortions in three dimensional (3-D) geometric model. The 3-D geometrical model of an airborne SAR image depends on the SAR processor itself. Working at squinted model, i.e., with an offset angle (squint angle) of the radar beam from broadside direction, the aircraft motion instabilities may produce distortions in airborne InSAR geometric relationship, which, if not properly being compensated for during SAR imaging, may damage the image registration. The determination of locations of the SAR image depends on the irradiated topography and the exact knowledge of all signal delays: range delay and chirp delay (being adjusted by the radar operator) and internal delays which are unknown a priori. Hence, in order to obtain reliable results, these parameters must be properly calibrated. An Airborne InSAR mapping system has been developed by the Institute of Remote Sensing and Digital Earth (RADI), Chinese Academy of Sciences (CAS) to acquire three-dimensional geo-spatial data with high resolution and accuracy. To test the performance of the InSAR system, the Validation/Calibration (Val/Cal) campaign has carried out in Sichun province, south-west China, whose results will be reported in this paper.

On the filtered Smith predictor for MIMO processes with multiple time delays

This paper discusses about a unified implementation structure of the filtered Smith predictor (FSP) for MIMO processes with multiple time delays. Two kinds of dead-time free models are analyzed in order to extend the original properties of the SISO Smith predictor to MIMO processes with multiple time delays. It is demonstrated that FSP strategy can be applied to control open-loop unstable processes with multiple time delays by considering a model without any input, output or internal coupling delays. Moreover, for open-loop stable processes, it is shown that the FSP scheme can be used to speed-up disturbance rejection of processes with multiple time delays by using a nominal model without delay. Different simulation examples are used to illustrate the proposed strategy properties and advantages over other MIMO time-delay compensators. The results may be considered to control either square or non-square processes.

Stability, coherent spiking and synchronization in noisy excitable systems with coupling and internal delays

We study the onset and the adjustment of different oscillatory modes in a system of excitable units subjected to two forms of noise and delays cast as external or internal according to whether they are associated with inter- or intra-unit activity. Conditions for stability of a single unit are derived in case of the linearized perturbed system, whereas the interplay of noise and internal delay in shaping the oscillatory motion is analyzed by the method of statistical linearization. It is demonstrated that the internal delay, as well as its coaction with external noise, drive the unit away from the bifurcation controlled by the excitability parameter. For the pair of interacting units, it is shown that the external/internal character of noise primarily influences frequency synchronization and the competition between the noise-induced and delay-driven oscillatory modes, while coherence of firing and phase synchronization substantially depend on internal delay. Some of the important effects include: (i) loss of frequency synchronization under external noise; (ii) existence of characteristic regimes of entrainment, where under variation of coupling delay, the optimized unit (noise intensity fixed at resonant value) may be controlled by the adjustable unit (variable noise) and vice versa, or both units may become adjusted to coupling delay; (iii) phase synchronization achieved both for noise-induced and delay-driven modes.

Decay rate estimates for a weak viscoelastic beam equation with time-varying delay

Abstract We consider a weak viscoelastic beam equation with internal time-varying delay u t t + Δ 2 u − M ( ‖ ∇ u ‖ 2 ) Δ u + σ ( t ) ∫ 0 t g ( t − s ) Δ u ( s ) d s + 0 u t + a 1 u t ( x , t − τ ( t ) ) = 0 . By introducing suitable energy and Lyapunov functionals, we establish general decay estimates for the energy, which depends on the behavior of both σ and g .

The role of coupling strength and internal delay between compartments in shaping the bursting behavior of cortical neuron

Bursting is a typical firing behavior intrinsically existing in neurons from many brain regions, which has been thought to have functional roles in neuronal reliable signaling and synaptic plasticity. Meanwhile, many factors have been put forward to participate in the modulation of bursting behavior during the past decades. Here, in this research, the modulation of bursting behaviors was numerically investigated in a two-compartment model of cortical pyramidal neuron using the coupling strength and time delay between compartments as control parameters. By means of computer simulations, we showed that, for larger coupling strengths and smaller delays between the two compartments, a wide range of regular bursting can be observed, while too large coupling strengths and time delays would cause the model neuron to be quiescent. In addition, the dynamical firing range of regular spiking can be also obtained, which has two parts: one part corresponds to small coupling strengths irrespective of the values of time delay, while another part corresponds to larger coupling strengths and delays. These results suggested that coupling strength and internal time delay between the inner compartments possess potential roles in modulating the dynamical bursting behavior of neurons.

Energy decay of solutions for a wave equation with a constant weak delay and a weak internal feedback

In this paper, we consider the wave equation with a weak internal constant delay term: u 00 (x, t) Dxu(x, t) + m1(t) u 0 (x, t) + m2(t) u 0 (x, t t) = 0 in a bounded domain. Under appropriate conditions on m1 and m2, we prove global existence of solutions by the Faedo-Galerkin method and establish a decay rate estimate for the energy using the multiplier method.

Cluster Synchronization of Stochastic Complex Networks with Markovian Switching and Time-Varying Delay via Impulsive Pinning Control

This paper studies the cluster synchronization of a kind of complex networks by means of impulsive pinning control scheme. These networks are subject to stochastic noise perturbations and Markovian switching, as well as internal and outer time-varying delays. Using the Lyapunov-Krasovskii functional, Itö’s formula, and some linear matrix inequalities (LMI), several novel sufficient conditions are obtained to guarantee the desired cluster synchronization. At the end of this writing, a numerical simulation is given to demonstrate the effectiveness of those theoretical results.

다목적실용위성 5호의 SAR 영상 검·보정을 위한 이동형 능동 트랜스폰더 개발

다목적실용위성 5호는 영상 레이더(SAR: Synthetic Aperture Radar)을 탑재하여 야간이나 구름이 있는 지역에 대해서도 지속적인 영상촬영이 가능하다. 발사 후 초기 운영 시험에서는 SAR 탑재체에 의해 관측된 영상에 대한 기하 및 복사 보정을 수행한다. 이러한 보정은 지표상의 위치 및 RCS(Radar Cross Section)을 알고 있는 보정장치에서 반사된 SAR 신호에 의해 나타난 영상 픽셀에서의 위치 및 값을 이용하여 처리된다. 이러한 보정을 위해 기존 반사기와 달리 능동 트랜스폰더는 RCS 값을 변경할 수 있으며, 내부 시간 지연 기능에 의해 가상의 위치로 이동하는 효과를 영상에서 나타낼 수 있다. 본 논문에서는 능동 트랜스폰더의 개발에 필요한 요구사항을 도출하여 이로부터 설계, 조립 및 시험결과를 정리하였다. KOMPSAT-5(KOrea Multi-Purpose SATellite-5) has a benefit of continuously conducting its mission in all weather and even night by loading SAR(Synthetic Aperture Radar) payload, which is different from optical sensor of KOMPSAT-2 satellite. During IOT(In-Orbit Test) periods, SAR image calibration should be conducted through ground target of which location and RCS is pre-determined. Differently from the conventional corner reflector, active transponder has a capability to change its internal transfer gain and delay, which allows active transponder to be shown in a pixel of SAR image with very high radiance and virtual location. In this paper, the development of active transponder is presented from design to I&T(Integration and Test).

GENERAL DECAY RATE ESTIMATE FOR THE ENERGY OF A WEAK VISCOELASTIC EQUATION WITH AN INTERNAL TIME-VARYING DELAY TERM

In this paper we consider the weak viscoelastic equation with an internal time-varying delay term $$u_{tt}(x,t)-\Delta u(x,t)+\alpha(t)\int_{0}^{t}g(t-s)\Delta u(x,s)\, {\rm d}s +a_{0}u_{t}(x,t)+a_{1}u_{t}(x,t-\tau(t))=0$$ in a bounded domain. By introducing suitable energy and Lyapunov functionals, under suitable assumptions, we establish a general decay rate estimate for the energy, which depends on the behavior of both $\alpha$ and $g$.

Patient care pathways under the model of integrating tuberculosis service with general hospitals in China

To report care pathways of tuberculosis (TB) patients under the integrated model, where TB clinical service is provided by a general hospital instead of the TB dispensary, with the aim of providing policy recommendations for TB care reforms in China. Six counties implementing the integrated model were randomly selected, and 50 TB patients in each county participated in a questionnaire survey. Of the 301 participants, 82 visited only the TB designated hospital. A patient visited a median of two health providers in total. The median external provider delay and internal provider delay were 1 and 0 day, respectively. The median out-of-pocket medical costs were US$379 in total; US$293 in the TB units and US$0 in other health units in the TB designated hospital. Logistic regression analyses suggested that patients who visited the primary care facilities first tended to have longer external delays (OR = 5.71) than patients who visited the other hospitals (OR = 10.16). The integrated model is promising as it reported relatively fewer patient pathways and shorter delays than the dispensary model. However, the integrated model did not reduce patient out-of-pocket costs.