The Role of Network Topologies in the Optical Core of IP-over-WDM Networks with Static Wavelength Routing

In this paper, we present a performance analysis of network topologies for the optical core of IP-over-WDM networks with static wavelength routing. The performance analysis is focused on regular degree four topologies, and, for comparison purposes, degree three topologies are also considered. It is shown that the increase of the nodal degree from three (degree three topology with smallest diameter) to four (degree four topology with smallest diameter) improves the network performance if a larger number of wavelengths per link is available. However, the influence of wavelength interchange on the nodal degree gain is small. The performance of regular degree four topologies with smallest diameter is also compared with the performance of mesh–torus topologies (which are also degree four topologies), and it is shown that the blocking probability of degree four topologies with smallest diameter is about two orders of magnitude lower than the blocking probability of mesh–torus topologies. It is also presented a performance comparison of WDM-based networks with nodal degrees ranging from two to five and it is shown that the increase of the nodal degree from two to three leads to high nodal degree gains, while de increase of the nodal degree from four to five leads to low nodal degree gains. These results show that degree three and degree four topologies are very attractive for use in the optical core of IP-over-WDM networks.     

Noise modeling for RF CMOS circuit simulation

The RF noise in 0.18-/spl mu/m CMOS technology has been measured and modeled. In contrast to some other groups, we find only a moderate enhancement of the drain current noise for short-channel MOSFETs. The gate current noise on the other hand is more significantly enhanced, which is explained by the effects of the gate resistance. The experimental results are modeled with a nonquasi-static RF model, based on channel segmentation, which is capable of predicting both drain and gate current noise accurately. Experimental evidence is shown for two additional noise mechanisms: 1) avalanche noise associated with the avalanche current from drain to bulk and 2) shot noise in the direct-tunneling gate leakage current. Additionally, we show low-frequency noise measurements, which strongly point toward an explanation of the 1/f noise based on carrier trapping, not only in n-channel MOSFETs, but also in p-channel MOSFETs.     

Realization of modular multidimensional complex digital filters using GIC concept

It is known that complex digital filters possess certain advantages over real digital filters in processing complex signals such as increased computational speed and efficiency. In this paper, a simple and systematic procedure which can be implemented through a computer program is presented for realizing a specific class of multidimensional (M-D) complex digital filters. The proposed filter structures are derived from analog reference configurations comprising generalized immittance converters and resistors by making use of wave concept. These filters possess many salient properties such as low noise, low sensitivity and capability of realizing multiple transfer functions simultaneously which are inherited from the reference analog filters they are derived from. These features make them attractive for very large-scale integrated (VLSI) implementation. It is shown that the proposed filter structures can be obtained directly from the specified M-D discrete transfer function without the need for realizing any analog reference configuration.     

Deep‐UV Photochemistry and Patterning of (Aminoethylaminomethyl)phenethylsiloxane Self‐Assembled Monolayers

The 193 nm photochemistry of (aminoethylaminomethyl)phenethylsiloxane (PEDA) self‐assembled monolayers (SAMs) under ambient conditions is described. The primary photodegradation pathways at low exposure doses (< 100 mJ cm^–2) are benzylic C–N bond cleavage (ca. 68 %), with oxidation of the benzyl C to the aldehyde, and Si–C bond cleavage (ca. 32 %). Amine‐containing photoproducts released from the SAM during exposure remain physisorbed on the surface, where they undergo secondary photolysis leading to their complete degradation and removal after ca. 1200 mJ cm^–2. NaCl(aq) post‐exposure rinsing removes the physisorbed materials, showing that degradation of the original PEDA species (leaving Si–OH) is substantially complete after ca. 450 mJ cm^–2. Consequently, patterned, rinsed PEDA SAMs function as efficient templates for fabrication of high‐resolution, negative‐tone, electroless metal and DNA features with good selectivity at low dose (i.e., ca. 400 mJ cm^–2) via materials grafting to the intact amines remaining in the unirradiated PEDA SAM regions.     

Short-term frequency stability of clock generators for multigigahertz rapid-single-flux quantum digital circuits

Superconducting digital systems based on Josephson junctions have generally used a synchronous timing strategy. A master clock signal is used to delimit a data window during which the system changes state and data is transferred from one block to the next. The temporal stability of the clock signal has a profound effect on the performance of rapid single flux quantum (RSFQ) digital systems. In particular, short-term clock fluctuations, or clock jitter, can degrade system performance due to the hazard of timing constraint violations. The successful development of large-scale RSFQ digital systems will require highly stable multigigahertz on-chip clock sources. To meet this need, methods for characterizing and measuring the short-term stability of such sources are required. We identify the relevant figure of merit to characterize and compare various clocks: the cycle-to-cycle standard deviation of the clock periods. We present experimental techniques for the measurement of this figure of merit and apply them to the measurement of jitter in a clock generator used often in RSFQ systems, the ring oscillator. High-frequency phase noise measurements found the jitter of a 9.6-GHz clock to be in the range from 0.6% to 0.36% of the clock period. The measured values of clock jitter fell within the 95% confidence interval of our stochastic circuit simulations. This was sufficient evidence to conclude that thermal noise from the resistors in the circuit may be the dominant source of jitter in the ring oscillator.     

FDTD simulation of 30 /spl mu/m diameter polymer micro-ring

Numerical results on polymer surrounded by an air micro-ring coupled to waveguides are presented. The FDTD method predicts a filter width of 1.4 nm and an extraction efficiency of almost 80% for a gap of 0.15 /spl mu/m.     

Examining pre-adoption interest in online innovations: an exploratory study of e-service personalization in the public sector

In order to better understand why public organizations develop interest in online innovations, this paper develops a revised model of technological innovation with an emphasis on socio-technical factors associated with electronic service delivery. This model focuses on three primary dimensions of online innovation: perceived need, technical capacity, and risk mitigation. It is hypothesized that these three dimensions will have the greatest influence on the development of pre-adoption interest in a new online innovation. This model is then used to examine a single online innovation, personalization of online government information and services. Data from a survey of local governments is used to test the theory. A regression model was estimated from the survey data. Results suggest that perceived need, financial costs, and the ability to mitigate the risks associated with privacy issues each influence the level of interest in personalized online services. The results suggest that public organizations must find reliable means of determining external demand for online innovations, as well as reducing the risks associated with each specific type of online innovation prior to adoption.