Evaluation of the coupled multielectrode array sensor as a real-time corrosion monitor

Coupled multielectrode array sensors made of carbon steel and stainless steels were evaluated and compared with electrochemical noise (EN) sensors. Good correlations between sensor signals and solution corrosivity were observed for all multielectrode array sensors. Some correlation between the average pit index and solution corrosivity was observed for the carbon steel EN sensors, but not for the stainless steel EN sensors. The time-average noise resistances from the stainless steel EN sensors correlate well with solution corrosivity. There were, however, large random fluctuations and drifting for all EN signals, which make the EN sensors unreliable as real-time monitors.     

A nano-plasmonic HMIM waveguide based concurrent dual-band BPF using circular ring resonator

This article analyzes the transmission line characteristics of plasmonic hybrid metal insulator metal (HMIM) waveguide, circular ring resonator (CRR) based dual-band band-pass filters with two transmission poles in both pass-bands in the optical regime using coupled line feed. The transmission line characteristics of an HMIM waveguide, such as characteristic impedance (ZPV), effective refractive index (neff) and propagation length (Lspp), have been obtained by using full wave simulation. Using basic HMIM slot waveguide, a CRR with periodic loading of double- and triple-ring CRR is numerically analyzed. Two input ports have been used for excitation, which are located at the separation of 180° positions along the CRR, and are coupled with the ring by parallel coupled lines, producing the dual pass-bands with the synchronous excitation of two transmission poles. The proposed double-ring dual-band band-pass filter (DR-DB-BPF) offers 35 dB extinction ratio (ER), 299.69 nm free spectral range (FSR) and narrow band full width half maximum (FWHM) of 78.057—112.43 nm. The triple-ring DB-BPF (TR-DB-BPF) has 22.5 dB ER, FSR of 292.18 nm and FWHM of 42.751—59.58 nm. The proposed filters are very useful in the development of dual-band filters for electronic photonic integrated circuits (EPICs), as the optical signals are filtered at two wavelengths simultaneously.     

Topology design and bridge-capacity assignment for interconnecting token ring LANs: A simulated annealing approach

We address the problem of determining the topology and bridge-capacity assignments for a network connecting a number of token rings via source-routing bridges. The objective is to minimize the cost of bridge installations while meeting the network users' performance requirements. The problem is modeled as a mixed 0–1 integer program. A comparison is given between two solution algorithms: a simulated annealing algorithm using the flow-deviation algorithm for each routing subproblem, and a drop algorithm using the simplex method for the same subproblems to provide benchmark solutions. In the former algorithm, the routing subproblem is formulated as a nonlinear program with penalty functions to model node and link capacity constraints, and in the latter as a multicommodity flow model with the same capacity constraints. Computational results show that the simulated-annealing/flow-deviation algorithm produced substantially better solutions than the LP-based drop algorithm.     

Experimental measurement of gain in erbium-doped fluoride fiber amplifier in the 850-nm signal band

In this letter, we report an efficient single-mode Er/sup 3+/ doped fluoride fiber amplifier (EDFFA) in the 850 mn signal band. The Ti-sapphire laser was used to pump the EDFFA at 792 mm with an estimated absorbed pump power of 35 mW. The EDFFA used a 4.2 meter long NA=0.39, /spl lambda//sub c/=850 nm fluoride fiber as the active medium. A peak gain of 25 dB was observed at 852 mm. The gain was measured for a 10 nm region between 847.5 mn and 857.5 nm. The 3 dB gain bandwidth is less than 3 nm. However, the gain exceeded 20 dB over wavelength region of at least 7.5 nm. The gain and the gain bandwidth can be further increased by optimizing the length of the active fiber.     

Comparison of satellite and cellular architectures for downlink broadcast data transmission

Traditional voice and video‐oriented networks such as the cellular and satellite networks are being increasingly used to carry data traffic. We endeavour to compare the downlink broadcast performance of the two architectures against each other on the basis of energy consumption, end‐to‐end delay and maximum stable throughput. The architectures are modelled as systems of Geo/G/1 queues. Queuing theory arguments and then sample‐path based comparisons are used to show that the satellite architecture while being more energy‐efficient has a higher delay and a lower maximum throughput. The variation of energy and delay with the total number of receiver nodes is also studied. Copyright © 2006 John Wiley & Sons, Ltd.     

The Impact of Mobility on Cellular Network Configuration

This paper proposes a model for configuring cellular networks to study the dynamics of mobility between a single cell and its adjacent cells. It differs from most models considered in the literature by explicitly incorporating the dependency between the handoff rate and the system state. Besides, the handoff rate is also a function of cell size and subscriber mobility. Extensive computational experiments were done to study the impact of various input parameters on specific performance measures. Several observations are made regarding the system performance and as to how they are affected by the complex interaction between subscriber mobility, cell size, number of channels and the mean call initiation rate. The results of these experiments show that the proposed model, where handoff rates are state-dependent, captures additional traffic due to mobility when compared to the traditional method of modeling handoffs using information about the average behavior. Finally, the economic impact of mobility on system configuration decisions is analyzed. Though an approximation, the above work provides interesting insights about the impact of mobility in configuring cellular networks.     

Waveguide Cross Section and Background Magnetic Field Tapers for Broadbanding a Gyro-TWT

The gyro-TWT in a cylindrical waveguide of linearly-tapered cross section was analyzed for the gain-frequency response, using the Pierce-type gain equation. The taper in the waveguide cross section was adjusted for wide device bandwidths, either by changing the taper angle, while keeping the interaction length to be constant, or by changing the interaction length, while keeping the initial and final radii of the waveguide constant. Tapering led to the prediction of wide bandwidths, though at the cost of gain, as compared to a non-tapered device. The range of the DC background magnetic flux density relative to its grazing-point value was identified as a crucial parameter for large gains, with appreciable bandwidths, and minimum mode mixing in a tapered device, the latter in general facing more mode competition than a non-tapered device.     

The effect of deterministic spatial variations in retrograde wellimplants on shallow trench isolation for sub-0.18 μm CMOS technology

The high energy retrograde well implants for sub-0.18 microns CMOS are done at a normal or near normal incidence to minimize the shadowing due to the thick photoresist edges. The endstation geometry in a high energy implanter results in an incident angle variation across the wafer, which causes strong spatial variations in the well profile and can negatively impact device performance. We show that the spatial variations can have significant impact on shallow trench isolation (STI), by causing in a deterministic pattern the failure of STI devices on a wafer. These spatial variations are important and need to be taken into consideration for STI design