This paper explores two issues on TOP performance over ATM networks: ABR parameter tuning and performance comparison of binary mode ABR with enhanced UBR services. Of the fifteen parameters defined for ABR, two parameters dominate binary mode ABR performance: Rate Increase Factor (RIF) and Rate Decrease Factor (RDF). Using simulations, we study the effects of these two parameters on TOP over ABR performance. We compare TOP performance with different ABR parameter settings in terms of through-puts and fairness. The effects of different buffer sizes and LAN/WAN distances are also examined. We then compare TOP performance with the best ABR parameter setting with corresponding UBR service enhanced with Early Packet Discard and also with a fair buffer allocation scheme. The results show that TOP performance over binary mode ABR is very sensitive to parameter value settings, and that a poor choice of parameters can result in ABR performance worse than that of the much less expensive UBR-EPD scheme.

In a previous paper Smallwood and Paez (1991) showed how to generate realizations of partially coherent stationary normal time histories with a specified cross-spectral density matrix. This procedure is generalized for the case of multiple inputs with a specified cross-spectral density function and a specified marginal probability density function (pdf) for each of the inputs. The specified pdfs are not required to be Gaussian. A zero memory nonlinear (ZMNL) function is developed for each input to transform a Gaussian or normal time history into a time history with a specified non-Gaussian distribution. The transformation functions have the property that a transformed time history will have nearly the same auto spectral density as the original time history. A vector of Gaussian time histories are then generated with the specified cross-spectral density matrix. These waveforms are then transformed into the required time history realizations using the ZMNL function.

Without the social will, no city can successfully Undertake the planning and programs necessary for meaningful progress toward sustainability. Social will derives from wellsprings of vital societal health. This paper presents an approach to helping cities in APEC member economies initiate a program for developing indicators of sustainability. Representative indicators of social capital and other aspects of civic engagement, as proxies for societal health, are presented.

Analysis of crosswell and three-component seismic data integrated with well logs have produced information on the distribution of subsurface heterogeneities below the In-Tank Precipitation facility at the Savannah River Site (SRS). The travel time P-wave tomogram and reflection imaging delineate lateral and vertical structural details of the formations. In particular, the high-resolution P-wave tomogram captures a low-velocity zone within the carbonates. This zone is surrounded by reflection events between depths of 150 and 200 ft. in the reflection imaging. The reflections are caused by the acoustic impedance contrast between the low velocity zone of `soupy` sand mixtures of unconsolidated materials and the more rigid and dense competent surrounded medium. The time-frequency analysis of full waveforms particle velocity identifies guided waves in form of leaky and normal modes at the depths of about 138 to 150 ft. This resulting change in lithology associated with the presence of guided waves is consistent with a velocity low observed in the vertical velocity profile determined from the inversion of three-component seismic data. This low-velocity zone intercepted by the wells H-BOR-34 and H-BOR-50 correlates with the conductive Griffins Landing Member, which is located above the carbonates. The result of the experiments demonstrate that the present …

We have constructed and fielded a multi-wavelength injection seeded mid-IR OPO source for DIAL. This OPO system was built for ground based remote sensing measurements of species with both broad (300 cm{sup -1}) and narrow absorption bandwidths (0.07 cm{sup -1} FWHM). The OPO utilizes a single frequency tunable diode laser for the injection seeded signal wavelength in the region from 6400 to 6700 cm{sup -1} and an angle phase-matched 5 cm LiNbO3 crystal to provide large tuning excursions on a slow time scale. The pump was a diode pumped Nd:YAG MOPA (9398 cm{sup -1}) running at 180 Hz. This pump source was repeatedly injection seeded with a different wavelength on each of film sequential shots forming a set of three pulses having wavelength separations on the order of 0.4 cm{sup -1} at a three color set repetition rate of 60 Hz. This combination of OPO signal and pump source produced a set of three time staggered idler wavelengths separated by 0.4 cm{sup -1} with the center wavelength tunable from 2700 to 3000 cm{sup -1}. This OPO system was used in field test experiments to detect the release of chemicals from a standoff distance of 3.3 Km. We present key OPO …

Optical parametric oscillators (OPOS) are useful devices to generate tunable radiation. The tuning characteristics of OPOs can lead to their utility in remote sensing applications. We have investigated injection-seeded OPOs to generate narrow-band Mid-JR radiation for this purpose. OPOs exhibit a resonance structure similar to that of a laser`s cavity limiting the frequency choices available. Also, the coupling of the electric fields of the three interacting waves can generate cavity resonances for OPOs which have no cold cavity resonances (i.e. non-resonant OPOS). The potential for generating multiple frequencies simultaneously from a single OPO is discussed. The generation of multiple output frequencies is accomplished by injecting either multiple signal or multiple pump frequencies to the OPO. A seeded SRO is found to be well-suited to generating spectrally pure and stable multi-line output when the input pump field is multiple frequency. The generation of sideband frequencies during multiple seeding is also observed experimentally and addressed theoretically. The spectral purity of the OPO output is related to the frequency separation of the multi-line input as compared to the OPO cavity resonance structure.

Pressures are mounting for a regime to verify the dismantlement of US and Russian warheads, as well as a system of international control over the weapons` fissile materials to assure irreversibility. There are at least four motivating factors for these measures: (1) as the United States and Russia lower their numbers of nuclear weapons, each side seeks assurance that the warheads are actually being dismantled; (2) by accounting for the fissile materials and placing them under effective controls, the potential for smuggling and theft is reduced; (3) a fissile materials cutoff is being discussed at the Conference on Disarmament in Geneva; verification of a US-Russian cutoff, as well as substantial reductions in fissile materials stockpiles, are seen as integral to the cutoff; (4) calls for total nuclear disarmament have greatly increased; dismantlement verification and international control of fissile materials are widely viewed as requisite steps toward this goal. There are many questions to be answered before the United States can agree to a warhead verification regime and international control over excess fissile materials, let alone total nuclear disarmament. Two of the most important are: What are the prospects for effective verification? and How much fissile material can be declared as …

The end of the cold war has resulted in excess plutonium-containing materials (PCMs) in multiple chemical forms. Major problems are associated with the long-term management of these materials: safeguards and nonproliferation issues; health, environment, and safety concerns; waste management requirements; and high storage costs. These issues can be addressed by conversion of the PCMs to glass: however, conventional glass processes require oxide-like feed materials. Conversion of PCMs to oxide-like materials followed by vitrification is a complex and expensive process. A new vitrification process has been invented, the Glass Material Oxidation and Dissolution System (GMODS) to allow direct conversion of PCMs to glass. GMODS directly converts metals, ceramics, and amorphous solids to glass; oxidizes organics with the residue converted to glass; and converts chlorides to borosilicate glass and a secondary sodium chloride stream. Laboratory work has demonstrated the conversion of cerium (a plutonium surrogate), uranium (a plutonium surrogate), Zircaloy, stainless steel, multiple oxides, and other materials to glass. Equipment options have been identified for processing rates between 1 and 100,000 t/y. Significant work, including a pilot plant, is required to develop GMODS for applications at an industrial scale.