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This paper presents a coastal migration index (CMI) useful for decision-making in the current scenario of sea-level rise (SLR) due to climate change. The CMI includes coastal human population density, degree of urbanization, and coastal-flooding penetration. Quantitative and qualitative statistical techniques and the geographic information system ArcGIS View 9.0 were used. Further, a panel of fifteen international experts in coastal management issues was consulted to establish and validate the CMI. Results led to three index components based on 22 indicators. CMI was applied in the state of Tamaulipas, Mexico and in Santiago de Cuba province, Cuba. According to CMI estimates, the risk levels associated with SLR for human settlements analyzed in Mexico and Cuba were 5.3% and 11.0%, respectively. The most severely affected communities will require resettlement. Meanwhile, the CMI determined that 15.8% of the Mexican territory studied will be able to withstand the effects of SLR through the management of engineering works that will protect human settlements. The CMI determined that 79.0%, in the case of Tamaulipas, as well as 89.0% of the Cuban territory, will not require new policies or guidelines to promote conservation and protection of coastal natural resources. Lastly, the method used allowed for creation of a CMI stoplight map useful to coastal decision-makers to adopt sound management actions.

Several transient wave trains containing an isolated plunging or spilling breaker at a prescribed location were generated in a two-dimensional wave flume using an energy focusing technique. Surface elevation measurements of each transient wave train were made at locations before and after breaking. Applying a nonlinear deterministic decomposition approach to the measured elevation, the free-wave components of the transient wave train were derived by excluding the contribution from bound-wave components. The comparison of the amplitude or energy spectra of free-wave components before and after a breaker can accurately reveal the energy dissipation as a function of frequency. It is found that the energy loss is almost exclusively from wave components at frequencies higher than the spectral peak frequency. Although the energy density of the wave components of frequencies near the peak frequency is the largest, they do not significantly gain or lose energy after the breaking. It is also observed that wave components of frequencies significantly below or near the peak frequency gain a small portion (about 12%) of energy lost by the high-frequency waves. These findings are quite different from the empirical formulas presently used for determining wave dissipation due to wave breaking. Hence, they have important implications to the ocean wave energy budget, specially to the energy transfer at frequencies below and near the spectral peak frequency.

Hydrographic data from the Gulf of Mexico (gulf) provide evidence that a western boundary current was set up by the interaction of an anticyclonic Loop Current (LC) ring with the continental margin of the western gulf during March-August 1985. The March 1985 geostrophic circulation reveals a remnant anticyclonic ring colliding with the slope. During this collision, two cyclonic rings were shed as the anticyclone transferred vorticity to the surrounding slope water. During July-August 1985, the ring triad weakened and evolved into a ∼900-km-long, north flowing, along-slope, western boundary current and cyclonic-anticyclonic ring pairs distributed throughout the central and western gulf. This western boundary current attained maximum northward flow speeds of 25 cm s−1 and an 8.3-Sv mass transport between 94°–96°W at 25°N. Our March-August 1985 observations reveal that the residence time and decay period of LC anticyclones in the western gulf may exceed 150 days. Within this time period the western gulf's cyclonic-anticyclonic vorticity field decayed ∼50%. Thus the western boundary current's evolutionary period, from its gestation to its absolute decay, is estimated to be of the order of 300 days. Although the presence of a western boundary current in the gulf has been attributed to the annual wind stress curl cycle [Sturges, 1993], our analyses of the western gulf March and July-August 1985 ring-driven geostrophic circulation and corresponding (January, February and May, June 1985) monthly mean synoptic wind stress curl distributions reveal that these constitute competing forcing mechanisms for the gulf's regional circulation. However, when very strong local forcing such as large eddies are present, the wind-driven background circulation is overwhelmed by such eddy forcing.

The winter water mass distributions in the western Gulf of Mexico, affected by the collision of a Loop Current anticyclonic ring, during January 1984 are analyzed. Two principal modes of Gulf Common Water (GCW) formation, arising from the dilution of the Caribbean Subtropical Underwater (SUW), are identified. Within the western gulf continental slope to the east of Tamiahua, the GCW is formed by the collision of anticyclonic rings. During these collision events, the SUW, entrapped at the core (200 m depth) of these features, is diluted by low salinity (36.1≤S≤36.3‰) water from the uppermost layer of the main thermocline. The end product of this mixture is GCW, which is further diluted by low salinity coastal water within the western gulf continental shelf. The second GCW formation mode is associated to the northerly wind stress which propagates over the western gulf during winter. During January, 1984, this wind stress gave rise to a 175 m mixed layer. This convective mixing destroyed the static stability of the summer thermocline and allowed for the partial dilution of the SUW with low salinity (S≤36.3‰) water from the western gulf continental shelf. Within the western gulf's upper 2000 m, the following water masses were identified to be present: GCW, SUW, Tropical Atlantic Central Water and associated dissolved oxygen minimum stratum, Antarctic Intermediate Water remnant, a mixture of the Caribbean Intermediate Water and the upper portion of North Atlantic Deep Water (NADW), and the NADW itself. The topographic distribution of these water masses' strata was dictated by the cyclonic-anticyclonic baroclinic circulation that evolved from the anticyclone's collision to the east of Tamiahua. Between the cyclonic and anticyclonic domains, the maximum pressure differential of these water masses' core occurrences was 150 to 280 dbar. The topographic transition zone defined by these strata occurred between the cyclonic and anticyclonic domains and coincided unambiguously with the anticyclone's collision zone. Within the continental shelf, we identified low temperature (12°C) and low salinity (31‰) coastal waters contributed by river runoff. Driven by the northerly wind stress, these coastal waters were advected toward the south hugging the coastline. The coastal and continental shelf waters demarcated a sea surface temperature, salinity, and dissolved oxygen discontinuity region that coincided with the horizontal baroclinic flow transition zone associated to the anticyclone's collision.

The most prevalent P2P application today is file sharing, both among scientific users and the general public. A fundamental process in file sharing systems is the search mechanism. The unstructured nature of real-world large-scale complex systems poses a challenge to the search methods, becasuse global routing and directory services are impractical to implement. In this paper, a new ant-colony algorithm, Adaptive Neighboring-Ant Search (AdaNAS), for the semantic query routing problem (SQRP) in a P2P network is presented. The proposed algorithm incorporates an adaptive control parameter tuning technique for runtime estimation of the time-to-live (TTL) of the ants. AdaNAS uses three strategies that take advantage of the local environment: learning, characterization, and exploration. Two classical learning rules are used to gain experience on past performance using three new learning functions based on the distance traveled and the resources found by the ants. The experimental results show that the AdaNAS algorithm outperforms the NAS algorithm where the TTL value is not tuned at runtime.

A great amount of natural and artificial systems can be represented as a complex network, where the entities of the system are related of non-trivial form. Thus, the network topology is the pattern of the interactions between entities. The characterization of complex networks allows analyzing, classifying and modeling the topology of complex networks. The degree distribution is a characterization function used in the analysis of complex networks. In this work a comparative study of the degree distribution for three different instances of the Internet was carried out, with information about the interconnection of domains. The Internet has a degree distribution power-law, that is, it has a great amount of weakly connected domains while a few domains have a great number of connections. Our results show that Internet has a dynamic growing maintaining the degree distribution power-law through the time, independently of the growth in the number of domains and its connections.

Wave energy dissipation and energy transfer among wave components during the directional wave breaking are investigated experimentally. Directional breaking waves in deep water were simulated by focusing the multi-frequency and multi-directional wave components at a designed location based on constant wave amplitude and constant wave steepness frequency spectrum. The incipient and plunging breakers with the same spectral characteristics were generated by applying the different scale factors on wave amplitude. The time series of surface wave elevation were measured around the wave focusing point using a wave gauge array to examine the variation of directional spreading function. The free wave components of a directional wave train are separated from bound wave components by nonlinear decomposition based on directional hybrid wave model accurate up to second order. The local free wave components derived from nonlinear decomposition still include directional dispersion effect. A spatial variation of free wave packet due to directional dispersion is estimated by comparing incipient breaking wave packets at corresponding locations. When the bound wave components and directional dispersion effect are removed from the plunging breaking wave train, a variation of the directional wave spectrum of resultant free wave components before and after the wave breaking is solely responsible to wave energy dissipation and transfer between free wave components. By comparing free wave components of a plunging breaking wave packet before and after the wave breaking, the characteristics of energy dissipation and energy transfer caused by wave breaking are investigated and their dependences on frequency are analyzed. The breaking in deep water significantly dissipates wave energy in the upper region of peak-frequency band while enhances wave energy slightly in the low-frequency band by energy transfer.

This paper proposes new frequency dependence for the empirical formulas presently used to determine wave energy dissipation in ocean wave models. Using an energy focusing technique, several unidirectional transient wave trains were generated. Each of the transient wave train contained an isolated plunging or spilling breaker. By comparing the energy spectra of free-wave components before and after breaker it was found that: 1)the energy loss as function of frequency is almost exclusively from wave components at frequencies higher than the spectral peak frequency; 2)although the energy density of the wave components near the peak frequency are the largest, they do not significantly gain or lose energy after breaking; and 3)wave components of frequencies significantly below or near the peak frequency gain a small portion (about 12%) of energy lost by the high-frequency waves. The empirical formulas presently used to determine white-capping dissipation (Komen et al. 1994; Tolman and Chalikov 1996; Booij 1999) do not agree with the above spectral distribution of energy dissipation. Analysis of the dissipation distribution obtained by Meza et al. (2000), suggest that the dependence of the dissipation rate on the frequency should be described by, (ωωp) (1 − (ωωp) E(ω), where ω is the wave frequency, ωp is the spectral peak frequency and E(ω) is the energy density spectrum. An energy dissipation source function with such a frequency dependence is being implemented and tested in a third generation wind wave model.Copyright © 2002 by ASME

During October-November 1986 the baroclinic circulation of the central and western Gulf of Mexico was dominated by an anticyclonic ring that was being bisected by two north and south flanking cyclonic rings. The baroclinic circulation revealed a well-defined cyclonic-anticyclonic-cyclonic triad system. The anticyclone's collision against the western gulf continental slope at 22.5°N, 97°W originated the north and south flanking cyclonic rings. The weakening of the anticyclone's relative vorticity, during the collision, was compensated by along-shelf north (26 cm s−1) and south (58 cm s−1) jet currents and by the anticyclone's flanking water mass's gain of cyclonic vorticity from lateral shear contributed by east (56 cm s−1) and west (42 cm s−1) current jets with individual mass transports of ∼18 Sv. Within the 0–1000 and 0–500 dbar layers and across 96°W the magnitudes of the colliding westward transports were 17.80 and 8.59 Sv, respectively. These corresponding transports were 85 and 94% balanced by along-shelf jet currents north and south of the anticyclone's collision zone. This indicates that only minor amounts (