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This study addresses the issue of robust H∞ control for a class of uncertain Takagi-Sugeno fuzzy systems with distributed time delay and non-linear perturbations. By employing a new Lyapunov-Krasovskii functional together with linear matrix inequality (LMI) technique, a new set of delay-dependent conditions are derived to achieve the robust stabilisation of uncertain fuzzy systems for a prescribed disturbance attenuation level γ > 0. The state feedback H∞ control law can be obtained by solving the corresponding LMIs. Further, some numerical examples are provided to demonstrate the effectiveness of the obtained results. The results reveal that the proposed theory significantly improve the allowable upper bounds of the delays over some existing results. [ABSTRACT FROM AUTHOR]

This study is concerned with the problem of state estimation using delayed measurements, especially when the delay is uncertain. In real-world applications, measurements are often randomly delayed, and hence not immediately available to the filter when taken by a sensor. By modelling uncertain delay as a probabilistic density function, the effect of uncertain delayed measurements is accounted for by the proposed estimator, combined with the augmented state Kalman filter. Use of the uncertain delay model resolves the randomness of the delay, and the augmentation is used to handle the delayed measurements. Consequently, the proposed algorithm is able to provide consistent estimates, regardless of the uncertainty of the delay. Monte Carlo simulations using one-dimensional particle were conducted with three kinds of representative uncertainty models, based on Gaussian, gamma and uniform distributions. The simulations verified the reliability and consistency of the proposed estimator. [ABSTRACT FROM AUTHOR]

In multi-radio multi-channel wireless mesh networks (MRMC WMNs), the performance of transmission control protocol (TCP) significantly deteriorates when non-congestion packet losses occur. TCP-hop-oriented network Coding (HONC) is proposed in this study to improve the performance of TCP with hop-oriented network coding in MRMC WMNs. It combines a block of inter- and intra-flow packets that share a same next-hop node by random linear network coding, and then it forwards and acknowledges these blocks hop by hop. Distributed rate control and path selection algorithm is introduced to effectively utilise network resources and balance load from congested paths to non-congested ones. The simulations show that TCP-HONC achieves a significant throughput gain. Meanwhile, the end-to-end delay and delay jitter of TCP-HONC are relatively small even with a high loss rate. TCP-HONC outperforms TCP/NCend-to-end by 236% and TCP/NChop-by-hop by 143% in throughput and reduces the average end-to-end delay to 27 and 90%, when the packet loss rate on each link is 35%. Moreover, the resource is fairly allocated to different flows. TCP-HONC is also capable of balancing load among different paths and the queue length on bottleneck links is stable. The throughput gain achieved by TCP-HONC is the result of re-encoding data at intermediate nodes and the derived delay reduction benefits from the one-hop ACK and retransmission scheme. [ABSTRACT FROM AUTHOR]

The considered problem is robust controllability of linear systems with both multiple delays in control and structured parametric uncertainties. Under the assumption that the linear nominal system with multiple control delays is controllable, a sufficient condition is proposed to preserve the assumed property when system uncertainties are introduced. The application of the proposed sufficient condition is demonstrated in two examples. [ABSTRACT FROM AUTHOR]

This study presents a novel composite right/left-handed transmission line (CRLH TL) unit cell with high time-delay (TD) efficiency for the design of true-time-delay lines (TTDLs). Shorter inter-digital fingers are used in a symmetrical CRLH TL unit cell to reduce the size by 58% and form a compact CRLH TL unit cell. This reduces the left-handed (LH) capacitance, which is compensated by using open-circuited metallic vias on the fingers. A TTDL constructed by cascading a number of compact CRLH TL unit cells is designed and studied using computer simulation, and then fabricated on a PCB for measurements. For performances comparison, two other TTDLs of the same length implemented using the symmetrical CRLH TL unit cells and right-handed transmission line (RH TL) are also designed, fabricated and measured. Simulation and measurement results show that, for the same length of 30 mm, the TTDL implemented using the compact CRLH TL unit cells has much longer time delay than that of using the symmetrical CRLH TL unit cells and the RH TL. [ABSTRACT FROM AUTHOR]

Transmitted reference pulse cluster (TRPC) signalling was recently proposed for robust low-rate ultra-wideband (UWB) communications. TRPC provides significant performance gains over conventional transmitted reference (TR) UWB, and overcomes the critical long delay line problem associated with TR UWB. Thus, it is suited for practical implementation of a UWB communication system. The compact spacing of the pulses in TRPC leads to inter-pulse interference (IPI). In this study, the authors show that there exists an asymmetry between the two conditional distributions of the autocorrelation decision variable because of this IPI. This implies that the conventional zero decision threshold (ZDT) is not optimal for a TRPC autocorrelation receiver, and hence the authors derive the optimal maximum likelihood decision threshold. The authors propose two practical techniques for threshold determination. The first technique employs a training sequence whereas the other simply uses the decision variables of the received data signals to estimate the threshold. Simulation results show that in terms of the bit error rate (BER) performance, both the training-assisted adaptive decision threshold (TA-ADT) and the data-assisted ADT (DA-ADT) can achieve significant gains over the conventional ZDT-based detection for TRPC. [ABSTRACT FROM AUTHOR]

Designing a non-ideal delay line (DL) with phase distortion in a transmitted-reference ultra-wideband system with an autocorrelation receiver is a great technical challenge. Differing from the currently empirical design method of DL, a semi-analytic approach is proposed through Gaussian approximation of the expression for conditional bit error rate (BER), based on investigation on the degradation of average BER caused by a group delay ripple range (GDRR) over independent Nakagami-m fading channels. This GDRR-based design method can directly evaluate its effects on the system performance and determine the acceptable phase distortion level to trade-off the BER performance and system complexity. [ABSTRACT FROM AUTHOR]

In this Letter, the authors investigate the use of carbon nanotube-based field effect transistors (CNTFET) for the design of a ternary static random access memory (SRAM). The authors consider two designs - one using 8 transistors and the other using 14 transistors. Using circuit simulation models for CNTFETs, the authors show that both designs produce a functional ternary SRAM cell. The authors also measure the delay and power of the read-and-write operation of the ternary SRAM created using both models and show that the delays are comparable. [ABSTRACT FROM AUTHOR]

An improved technique to stabilise a class of first-order linear time-invariant dynamics with two delays is presented. It proposes to design a controller in which delay cross-talk feature (or delay coupling) is utilised to enhance the system's stability characteristics. The authors present some comparative observations vis-à-vis an earlier pioneering study, which is a widely used point of reference for this class of systems, however, without the delay cross-talk effect. Furthermore, the treatment here profits from a recently introduced methodology, called the 'cluster treatment of characteristic roots (CTCR)', for the stability assessment of these systems, differently from the earlier suggested procedures. With the introduction of the delay cross-talk term, the authors show that the new system may become stable for larger delay zones, which is otherwise impossible. In the text, we present several case studies to display the outcome of such a tool. [ABSTRACT FROM AUTHOR]

In this study, both full 3D electromagnetic and equivalent circuit modelling of a radio frequency microelectromechanical systems (RF MEMS) single-pole eight-throw rotary switch are reported for the first time. Excellent agreement has been achieved between measurements and modelled performance for frequencies up to 12 GHz. In order to validate the effectiveness of the modelling, a 2-bit true time delay phase shifter having a centre frequency of 2 GHz has been demonstrated. The traditional topology of the switched delay line was adopted with two rotary switches employed for signal routing. This phase shifter represents the first ever application of any RF MEMS rotary switch. It is shown that the switch model can accurately predict the measured performance of the phase shifter, without the need for adding new circuit elements or tweaking of model parameters. The low measured root mean square deviations of insertion phase from the predicted responses increase as 1.3°, 1.9°, 2.5° and 3.4° when the phase states are stepped through 0°, 90°, 180° and 270°, respectively. [ABSTRACT FROM AUTHOR]

Applications such as voice and video require network paths that satisfy several different quality of service (QoS) metrics, such as delay, jitter, packet loss rate and availability. The calculation of paths under multiple QoS metrics, such as the above four metrics, is a difficult problem since these metrics are in general incompatible. The authors propose a simple method for combining the above four QoS metrics into a single composite QoS metric which can be used as a link cost in Dijkstra's algorithm in order to calculate a path. The authors evaluated the proposed method in a multi-domain routing environment where domain reachability information is available through a service oriented architecture paradigm, and they show that it outperforms two commonly used methods. The results are also applicable to routing within a single domain. [ABSTRACT FROM AUTHOR]

This study addresses the stabilisation problem for a class of networked control systems (NCSs) with time delays and packet losses. Motivated by the fact that static state feedback control shows offset in the plant output when non-zero disturbance acts on NCSs, the proposed method emphasises the implementation issue and employs state feedback integral control to achieve non-zero disturbance rejection and zero steady-state error. The resulting closed-loop system is transformed into a discrete-time switched system, and the stability conditions are derived in terms of linear matrix inequalities (LMIs). The corresponding stabilising controller design technique is also developed based on the stability conditions. Simulation and experimental examples are given to illustrate the effectiveness of the obtained results. [ABSTRACT FROM AUTHOR]

A new control method for network-based control systems, with guaranteed closed-loop stability, is proposed. The method substantially enhances the conventional networked model-based predictive control (NMBPC) schemes. In conventional NMBPC methods, associated with a pre-specified range of possible time delays, a vector of stabilising control signals is determined and transmitted to the plant side of the network, where, based on the actually occurred time delay, just one entry of the control vector is selected and applied to the plant. In practice, stability issues may arise when the network time delay is not small enough. A modified method, using the plant-input mapping (PIM) discretisation technique, with the possibility of guaranteeing the closed-loop stability is introduced. In order to alleviate the deficiency of some existing transfer function-based methods, which implicitly assume a non-realistic zero initial condition at the outset of every sampling instant, a state-space representation is proposed. Simulation studies on well-known benchmark problems demonstrate the effectiveness of the proposed PIM-based NMBPC method. [ABSTRACT FROM AUTHOR]

This work describes a lumped-element balun for use in a miniature, coplanar waveguide frequency tripler pseudomorphic high electron mobility transistor microwave monolithic integrated circuit. The measurement results of the balun show a 1-dB gain balance and a 10 degrees phase balance from 11.6 to 13 GHz. It was used in the design of a 36-GHz monolithic tripler at the input port. A resonant inductor and capacitor (LC) filter was used to eliminate the fundamental frequency and a phase delay line was employed to enhance the third harmonic in the tripler. At 36 GHz, the tripler achieved as minimum conversion loss of 6.7 dB at an input power of 13 dBm; the suppressions of the fundamental and second harmonic frequencies were 24 and 27 dB, respectively. [ABSTRACT FROM AUTHOR]

A new memory-reliable controller design for a class of discrete-time systems with time-varying input delays is proposed. By assuming that the actuator fault obeys a certain probabilistic distribution, a new practical actuator fault model is presented. Based on this fault model and the known past information, an augmented system with time-varying delay or non-delay, similar to switched systems, is established. By using the Lyapunov-Krasovskii approach, a sufficient condition for the existence of reliable controller is expressed by linear matrix inequalities. An illustrative example is exploited to show the effectiveness of the proposed design procedures. [ABSTRACT FROM AUTHOR]

Most scan-based designs implement the scan enable as a slow speed global control signal, and can therefore only implement launch-on-capture (LOC) delay tests. Launch-on-shift (LOS) tests are generally more effective, achieving higher fault coverage with significantly fewer test vectors, but requiring a fast scan enable. A low cost solution for implementing LOS tests by adding a small amount of logic in each flip-flop to align the slow scan enable signal to the clock edge is presented. The new design is much more efficient when compared with other recent proposals and can support full LOS testing. It can be further modified for mixed LOC/LOS tests that achieve transition delay fault coverage approaching 95% for the ISCAS89 benchmarks. [ABSTRACT FROM AUTHOR]

Class-based traffic treatment frameworks, such as differentiated service (DiffServ), have been proposed to solve the scalability problem of flow-based approach for quality of service (QoS) provisioning. While these frameworks provide service differentiation according to traffic classes, the provision of QoS guarantee for individual flows, within a class, remains a challenging problem. In the paper, the authors present a novel multiservices mechanism, which is able to provide service curves assurance for per-flow deterministic delay guarantees. The core component of this mechanism is a new packet scheduling algorithm, called flow-state-dependent packet scheduling (FDPS), to handle different flows within the same class to provide end-to-end scheduling delay bound guarantees. The mechanism is based on an analysis that guides the flow admission control operation for class-based queueing delay bound. Using the packets' flow-states, FDPS provides fine granularity packet service differentiation within each class. By means of this property, the proposed mechanism achieves per-flow end-to-end delay bound independent of the number of intermediate nodes along the path of the flow. Another notable feature is that it can be integrated into a DiffServ framework as an enhancement for deterministic QoS guarantees. The performance of this mechanism is mathematically analysed to demonstrate its enhancements and ns-2 simulation experiments are used to validate the analytical results. [ABSTRACT FROM AUTHOR]

The realisation of switched-capacitor decimation filters employing transfer functions with fewer number of poles (outside the origin of the z plane) than zeros is presented. The design approach exploits trade-offs involving filter complexity, power consumption and sensitivity with respect to capacitance ratio errors. The filter structure is obtained by the polyphase decomposition of IIR transfer functions, and implemented by low-noise tapped delay lines comprising cascaded track-and-hold stages with staggered clocks. The main theoretical results are verified by computer-aided simulations and laboratory measurements carried out on a prototype decimation filter. [ABSTRACT FROM AUTHOR]

Traces collected at monitored points around the Internet contain representative performance information about the paths their probes traverse. If processed appropriately, basic measurement attributes, such as delay and loss, can be used to output conclusions about the performance status of the network, with subsequent applications in fault and performance management, network provisioning, traffic engineering and performance prediction. However, the task of analysis and extracting such valuable information from measurements only remains challenging. The Weibull mixture model, a method to characterise end-to-end network delay measurements within a few simple, accurate, representative and handleable parameters using a finite combination of Weibull distributions is presented. The model parameters are related to meaningful delay characteristics, such as average peak and tail behaviour in a daily profile, and can be optimally found using an iterative algorithm known as expectation maximisation. Studies on such parameter evolution can reflect current workload status and all possible network events impacting packet dynamics, with further applications in network management. The model is further tested and validated with real GPS synchronised measurements taken across the Internet, donated by RIPE NCC. [ABSTRACT FROM AUTHOR]

In deep-submicron technology, minimising the propagation delay and power consumption on buses is the most important design objective in system-on-chip design. In particular, the coupling effects between wires on the bus that can cause serious problems such as crosstalk delay, noise and power consumption. Most of the previous work on bus encoding targeted either (1) minimising the power consumption on bus, (2) minimising the crosstalk delay, or (3) exploiting the known probabilistic information of data, but not all of them. The authors propose a new bus-encoding algorithm that not only minimises the dynamic power consumption on bus but also eliminates the crosstalk delay. The authors achieve the combined objective of (1) and (2) by analysing, formulating and solving the problem of minimising a weighted sum of the self-transition and cross-coupled transition activities on bus in the context of the concept of self-shield encoding. From experiments using a set of benchmark designs, it is shown that the proposed encoding technique consumes 15.4–47.4% less power than existing techniques while totally eliminating the crosstalk delay. [ABSTRACT FROM AUTHOR]

A novel cyclic-prefix based delay-spread estimation technique for wireless OFDM systems is proposed. in particular, the authors propose a technique for estimating the delays and powers of multipath components when the channel is sparse, i.e. a few strong multipaths distantly spaced in time, and a technique for estimating the RMS delay-spread when the channel has a large number of sample-spaced multipath components. The proposed techniques are based on a multiple-argument correlation function which exhibits change of gradient according to the delay path arrival pattern, i.e delay times and powers. Numerical results demonstrate the accuracy of the proposed techniques in estimating the relative timing and the power of delay paths for a sparse multipath channel, and the RMS delay-spread for a sample-spaced multipath channel. Moreover, the RMS delay-spread estimation can be used adaptively to operate the MMSE channel estimation process in the OFDM receiver at near optimum. [ABSTRACT FROM AUTHOR]

A criterion for the global asymptotic stability and uniqueness of the equilibrium point of uncertain cellular neural networks with delay is presented. The uncertainties are assumed to be norm-bounded. The criterion is computationally efficient, since it is in the form of a linear matrix inequality. [ABSTRACT FROM AUTHOR]

The problem of sliding-mode control for a class of neutral delay systems with uncertainties in both the state matrices and the input matrix is considered. By selecting a sliding surface depending on the current state and delayed state, the paper gives a sufficient condition in terms of linear matrix inequalities (LMIs) such that the closed-loop system is guaranteed to be asymptotically stable. When LMIs are feasible, the design of the sliding surface and the slidingmode control law can be easily obtained by convex optimisation. State trajectories are attracted onto the sliding surface in a finite time and remain there for all subsequent time. A simulation illustrates the application of the method. [ABSTRACT FROM AUTHOR]

Describes a hybrid phase measuring system which is an adaptive development of traditional phase locked loops. Digital delay line; Vector field representation of propagating deep water ocean gravity waves; Compromise between phase error and the time taken to recover the tracking mode.

A novel mixed-mode 50% duty cycle corrector (DCC) based on a digital process is proposed. The DCC adopts both digital and analogue correction methods in which a half cycle delay line is used for coarse correction, and an analogue feedback loop based on full-MOSFETs for further fine tuning to achieve fast settling and high precision. The rising edge of the output clock has a constant delay compared to the input clock, which makes the DCC easy to cooperate with a delay locked loop. Simulated results using 0.13 µm CMOS technology show that the output duty cycle is corrected to 50±0.22% throughout the input duty cycle range from 20 to 80% in the frequency range 200 MHz-2 GHz. [ABSTRACT FROM AUTHOR]

The learning curves of the filtered-X least-mean-square (LMS) algorithm are theoretically obtained using a statistical-mechanics approach. The direction cosines among the vectors of an adaptive filter, its shifted filters, and an unknown system are treated as macroscopic variables. Assuming that the tapped-delay line is sufficiently long, simultaneous differential equations are obtained that describe the dynamical behaviours of the macroscopic variables in a deterministic form. The equations are solved analytically and show that the obtained theory quantitatively agrees with computer simulations. In the analysis, neither the independence assumption nor the few-taps assumption is used. [ABSTRACT FROM AUTHOR]

A single-sided left- and right-handed metamaterial, which is called a triangular left- and right-handed resonator composed of symmetric paired triangular split-rings and middle wires, is discussed. The frequency dependence of the transmittance shows a right-handed transmission window centred around 9.9 GHz and a left-handed transmission peak around 10.9 GHz, both displaying comparable high transmission levels. The left- and right-handed behaviour is assessed by retrieved effective parameters, surface current distribution and comparison of the phase delay between two slabs of different units. [ABSTRACT FROM AUTHOR]

Presented is a new state-tracking migration policy which is adaptively integrated with immediate restart and selective preemption techniques for risk-resilient job allocation in high-throughput computing environments. The proposed approach guarantees the maximum reduction of inevitable delays with relatively low migration costs. Simulation results show that the integrated migration policy averagely outperforms the conventional mechanisms by 26% in makespan and 33% in throughput, respectively, under various job's burstiness. [ABSTRACT FROM AUTHOR]

A wide duty cycle range and small static phase error synchronous mirror delay (SMD) for system-on-chip (SoC) applications is presented. The conventional SMD accepts only the pulsed clock signal and has large static phase error. The proposed SMD uses the edge-trigger mirror delay cell to enlarge the input duty cycle range and the blocking edge-trigger scheme to ensure functionality and performance. Moreover, phase error can be reduced by the proposed delay-matching structure and fine-tuning delay line with a high-resolution delay cell. Simulation results of SMD show that the input clock duty cycle range is from 20 to 80% and the worst static phase error under different process, voltage, and temperature conditions can achieve 18 ps at 400 MHz. [ABSTRACT FROM AUTHOR]

Unlike conventional blind signal separation (BSS) methods estimating unmixing channels, an improved BSS method by estimating mixing channels in time domain is presented. Compared to the unmixing channels with IIR characteristics the mixing channels can be approximated by FIR filters with fewer time delays, and the proposed method demonstrates superior performance for the same training data. [ABSTRACT FROM AUTHOR]

A new second-order all-pass filter with maximum achievable delay-bandwidth-product (DBW) is presented. The proposed circuit will be used as a wideband delay element in impulse radio ultra-wideband transceivers. Benefiting from a simple architecture, the proposed circuit achieves a 60 ps delay across a 10 GHz bandwidth, which is the largest delay ever reported over such a wide bandwidth. In addition, the most noticeable advantage of this delay circuit is the small variation of group delay across a wide frequency range, which means negligibly small phase distortion introduced by the circuit. [ABSTRACT FROM AUTHOR]

A technique for the distortion reduction of delayed pulses in single and cascaded slow light delay lines is demonstrated. The method is based on the overlap of different independent Brillouin gains. With three Brillouin lines a distortion reduction of around 30% in a two-segment delay line was achieved. [ABSTRACT FROM AUTHOR]

A new method of recovering the group delay of a fibre Bragg grating (FBG) by iterative processing of the amplitude of the measured transmission spectrun is described. This method is extremely simple, fast and accurate, and works well for any type of FBG, even when the measured spectra are fairly noisy. [ABSTRACT FROM AUTHOR]

A design of a tunable microwave photonic filter for noise suppression and channel interference mitigation in the front-end stage after the receiving antenna of an UMTS base station is presented. The filter provides a tunable and very high selective performance (5 MHz along the 1935–1977 MHz band) with 14 dB suppression in the stopband using 30 fibre Bragg gratings and a reconfigurable dispersive delay line. [ABSTRACT FROM AUTHOR]

A variable optical delay circuit that employs a fibre loop with highly nonlinear fibre parametric wavelength converters is described. The delay time is determined from the number of circulations, which is controlled by the initially selected wavelength of the signal. No additional amplifier to compensate for the circulation loss is required. [ABSTRACT FROM AUTHOR]

A novel sampling scheme for coarse-fine time-to-digital converters (TDCs), whose architecture commonly comprises a synchronous counter as a coarse part and delay-line based phase interpolator as a fine part, is proposed. The presented approach eliminates any error in the coarse counter and is superior in terms of mean time between failures as well as complexity, area and power consumption in comparison to previously reported solutions. [ABSTRACT FROM AUTHOR]

An analogously fine-tunable delay line in a standard 90 nm CMOS technology is proposed for use in on-chip measurements of asynchronous digital circuit elements. The implemented delay line achieves a maximum delay of 155 ps together with the possibility to fine and coarse tune the delay. Owing to its truly analogue tuning it can overcome the limitation of the minimum step sizes found in digital controllable delay lines. Performance verification of a produced test chip showed that a timing resolution of sub-picosecond is attained. Therefore the timing resolution of the proposed delay line exceeds that of common digital delay lines. [ABSTRACT FROM AUTHOR]

Time difference amplification is a technique which has been developed previously to facilitate the measurement of temporal events in circuits whose magnitudes are decreasing with the advances in technology. A technique is proposed which extends the time input difference (ΔTinput) range achieved by current methods from 40 to 70 ps. [ABSTRACT FROM AUTHOR]

Worst-case delay analysis is important for avionics full duplex switched Ethernet (AFDX) standardised as ARINC 664. The flow model of virtual link (VL) in the worst-case delay analysis of AFDX is inaccurate, which depends only on the parameters of VL and ignores the impact from the network, so it makes the worst-case delay analysis of AFDX impractical. A worst-case flow model of VL, which takes the worst impact from the network into account, is proposed to mend the worst-case delay analysis of AFDX. This worst-case flow model of VL is applied in one of the main theoretical approaches for worst-case delay analysis, the network calculus approach. It assists the network calculus approach to get the real upper bound of delay for VL. [ABSTRACT FROM AUTHOR]

The proposed ultrasound beamformer is based on the delay-and-sum beamforming principle. The circuit consists of several programmable delay lines. Each delay line is constructed by pipeline-operated sample-and-hold (S/H) stages with digitally-assisted delay control, which ensure delay-independent gain and good timing accuracy. The summation is realised in the charge domain using the charge-averaging method, which consumes virtually no extra die area or power. A prototype beamformer has been fabricated in a 0.35 µm CMOS process to interface nine transducer elements. Measurement results show that this circuit consumes much less power and chip area than the prior art, while maintaining good accuracy and flexibility. [ABSTRACT FROM AUTHOR]

A new sigma delta (ΣΔ) modulator suitable for ultra-low power data converters is introduced. The proposed architecture is based on time encoding and quantisation using voltage controlled delays such as digital inverters. The delays together with a phase comparator implement a synchronous pulse width modulator (PWM) and a discrete time integrator. An additional analogue integrator provides second-order noise shaping and compensates the nonlinearity of the digital delay. Time quantisation of the two-level PWM signal allows implementing a multibit modulator without requiring linear multibit DACs. [ABSTRACT FROM AUTHOR]

An analysis of the delay characteristic of a voltage-controlled delay line (VCDL) exploiting a dual-input interpolating delay cell is presented and a design technique to incorporate the VCDL for a multiphase delay-locked loop is proposed. A recurrence relation of delay time of each delay cell in the VCDL and its closed-form expression show that the delay of each delay cell converges to a specific value with an error-decaying rate which depends on the weight of interpolation. A weight-adjusted delay cell is inserted to reduce the initial error and thereby the delay of the following delay cell converges fast. The validity of the analysis and the feasibility of the proposed scheme are verified by circuit simulation. [ABSTRACT FROM AUTHOR]

Distributional forms of Little's law relate the steady-state distributions of the number of customers in a queueing system (system content) and the time a customer spends in the system (delay). A new law for discrete-time multiserver queues is discussed, with single-slot service times, a first-come-first-served discipline and heterogeneous server interruptions. [ABSTRACT FROM AUTHOR]

An experiment was performed on the signal cancellation loop that utilises a carrier wave (CW) and wideband code division multiple access (WCDMA) signals to show that negative group delays can be used to cancel out positive group delays. According to the closed loop measurements, a 30 dB signal cancellation for a CW signal and a WCDMA 4FA signal were obtained over a 30 MHz bandwidth at the WCDMA downlink band, with a fabricated two-stage planar negative group delay circuit. [ABSTRACT FROM AUTHOR]

Electro-optical control of the terahertz phase in continuous-wave photomixing terahertz systems allows the determination of both terahertz amplitude and phase with a single sampling point per frequency. It is experimentally demonstrated that spectroscopic measurements can be performed by an order of magnitude faster with the single sampling point method without performance degradation compared to the standard delay line technique. [ABSTRACT FROM AUTHOR]

A new coherence-free optical delay line signal processing structure based on an unbalanced Mach-Zehnder interferometer containing an optical frequency shifter is presented. A coherence-free notch filter response is obtained by frequency shifting the delayed optical signal. Results demonstrate a significant improvement of the filter response stability and of the signal-to-noise ratio compared to the conventional delay line signal processor. [ABSTRACT FROM AUTHOR]

The surface acoustic wave (SAW) properties of delay lines with double electrode interdigital transducers on GdCa4O(BO3)3 crystal were measured at high temperatures. Low insertion loss changes and approximately linear dependence of the centre frequencies of the delay lines were obtained in the temperature range 20–500°C. For the XZ, YX and ZX orientations, temperature coefficients of frequency of about -80, -52, and -76 ppm/°C, respectively, were obtained. This crystal is promising for application in SAW high-temperature sensors. [ABSTRACT FROM AUTHOR]

A contention resolution scheme for slotted optical packet switching networks is proposed. The optical switch is augmented using auxiliary output ports connected to an auxiliary switch through fibre delay lines. The node architecture is illustrated and the results of the model show that packet blocking probability is improved using the proposed scheme. [ABSTRACT FROM AUTHOR]

A formula to predict the available path number in wideband mobile propagation is proposed. It is based on the authors' previously proposed empirical path delay profile model. The predicted values are in good agreement with measured data, demonstrating that the proposed formula is valid. [ABSTRACT FROM AUTHOR]

All-optical programmable logic must use recirculating delay lines for storage. Two approaches to minimising the latency inherent in delayline- based systems by treating the layout of code and data in memory as an integer linear programming (ILP) problem are presented. It is shown that, although this approach can generate optimal code for small routines, it will not scale enough to compile useful programs. [ABSTRACT FROM AUTHOR]