This paper presents a fast approach in the method of moments(MoM) analysis so as to obtain the non-uniform current distributions of cylindrical antennas with electrically large *** oblique incident field in its genera...
详细信息
ISBN:
(纸本)078037486X
This paper presents a fast approach in the method of moments(MoM) analysis so as to obtain the non-uniform current distributions of cylindrical antennas with electrically large *** oblique incident field in its general form and a delta-gap source are considered in the formulation of non-uniform current distributions. In the Galerkin's MoM procedure,the Fourier cosine series is considered as the entire domain basis function *** this formulation,the kernel is represented by a series of weighted spherical Hankel functions of the second kind and the convergence of this series is *** the result,the computation time is *** package is used to obtain and plot the current distributions along the cylindrical antennas.
Summary form only given. A novel scheme for passive synchronization of two independently mode-locked laser oscillators in a master slave configuration is presented. As an example the scheme is used to synchronize a pi...
详细信息
Summary form only given. A novel scheme for passive synchronization of two independently mode-locked laser oscillators in a master slave configuration is presented. As an example the scheme is used to synchronize a picosecond mode-locked Nd:YVO/sub 4/ laser (at 1064 nm) as the slave and a femtosecond mode-locked Ti:sapphire laser (around 850 nm) as the master oscillator. All optical synchronization is achieved by modulating the intracavity losses of the slave laser with the pulse train of the master oscillator.
Summary form only given. Modulation of intracavity losses is a powerful tool for controlling the laser dynamics, e.g. for active mode-locking and for synchronization of different lasers. In this paper we present an op...
详细信息
Summary form only given. Modulation of intracavity losses is a powerful tool for controlling the laser dynamics, e.g. for active mode-locking and for synchronization of different lasers. In this paper we present an optical device that allows for fast modulation of the intracavity losses by external illumination. The device is designed as a nonlinear semiconductor Fabry-Perot etalon consisting of two Bragg reflectors with a center wavelength of 1064 nm at the backside and the frontside of a 5-/spl mu/m-thick nonlinear medium - an InGaAs layer. The indium content is chosen such that the bandgap energy is 1.28 eV (/spl lambda//sub gap/ = 970 nm). While the device is highly reflecting for wavelengths longer than /spl lambda//sub gap/ around 1064 nm, radiation with /spl lambda/ < /spl lambda//sub gap/ generates carriers which change the index of refraction and, therefore, the reflectivity of the device in the vicinity of a Fabry-Perot resonance. To characterize the capabilities of the optically controlled Fabry-Perot-modulator (FPM), we performed a spectrally resolved two color pump probe measurement.
We introduce a class of multilevel recursive incomplete LU preconditioning techniques (RILUM) for solving general sparse matrices. This technique is based on a recursive two by two block incomplete LU factorization on...
详细信息
A new methodology is presented in this paper for resource management in a metacomputing environment using a hierarchy of homogeneous agents that has the capability of service discovery. The PACE [6] tools are used to ...
详细信息
Parallel programs executing on non-dedicated SMPs should be adaptive, that is, they should be able to execute on a dynamically varying environment without loss of efficiency. This paper defines a unified set of servic...
详细信息
high-performance networks require sophisticated management systems to identify sources of bottlenecks and detect faults. At the same time, the impact of network queries on the latency and bandwidth available to the ap...
详细信息
Gossip protocols provide a means by which failures can be detected in large, distributed systems in an asynchronous manner without the limits associated with reliable multicasting for group communications. However, in...
Gossip protocols provide a means by which failures can be detected in large, distributed systems in an asynchronous manner without the limits associated with reliable multicasting for group communications. However, in order to be effective with application recovery and reconfiguration, these protocols require mechanisms by which failures can be detected with system-wide consensus in a scalable fashion. This paper presents three new gossip-style protocols supported by a novel algorithm to achieve consensus in scalable, heterogeneous clusters. The round-robin protocol improves on basic randomized gossiping by distributing gossip messages in a deterministic order that optimizes bandwidth consumption. Redundant gossiping is completely eliminated in the binary round-robin protocol, and the round-robin with sequence check protocol is a useful extension that yields efficient detection times without the need for system-specific optimization. The distributed consensus algorithm works with these gossip protocols to achieve agreement among the operable nodes in the cluster on the state of the system featuring either a flat or a layered design. The various protocols are simulated and evaluated in terms of consensus time and scalability using a high-fidelity, fault-injection model for distributed systems comprised of clusters of workstations connected by high-performance networks.
Wireless systems, and mobile ad hoc networks in particular, are more likely to experience transmission and routing errors than their wired counterpart. Factors like the lack of infrastructure, node mobility, and rando...
详细信息
Wireless systems, and mobile ad hoc networks in particular, are more likely to experience transmission and routing errors than their wired counterpart. Factors like the lack of infrastructure, node mobility, and random radio link quality can contribute to significantly higher error rates in these networks. In addition, errors have a more serious impact on the network's resources, due to limitations in bandwidth and battery power inherent to the wireless ad hoc environment. This further complicates the task of designing scalable routing protocols, since larger networks are likely to experience even more errors, which may lead to slower convergence, longer end-to-end delay and unnacceptably high number of retransmissions. In this paper, we focus on the impact of error prevention and recovery on the scaling properties of on-demand protocols for ad hoc networks. Our analytical study, based on the evaluation of the Witness Aided Routing (WAR) and the Dynamic Source Routing (DSR) protocols, shows that the lack of localized intervention in handling errors translates eventually into lack of scalability, both in terms of performance and resource consumption. As route length increases, the performance of DSR degrades dramatically, especially in the presence of fluctuating wireless link quality. Even for small routes, DSR's lack of an error handling mechanism leads to very low probability of success when there is a non-zero probability that links are not bidirectional. On the other hand, WAR remains relatively insensitive both to the length of the route and to variations in mobility and call rates, and has a higher tolerance to radio link instability. This indicates that lacalized error correction can increase route effectiveness and alleviate the effects of short-lived radio link problems to an extent that allows the protocol to scale with the network size.
暂无评论