Hybrid vehicle power management modeling and refinement

The power management strategy in many hybrid vehicles is based on expert rules and thresholds. These rule-based strategies can result in good efficiency in term of fuel economy and emissions if their thresholds and rules are accurate. However, due to the complexity and the non-linearity of the hybrid powertrain, determining accurate thresholds and rules is neither explicit nor straightforward, and experts in most cases fail to define these thresholds and rules with enough accuracy. Based on this fact, the objective of this paper is to propose a method to improve this rule-based strategy by refining its thresholds and rules. To achieve this, we used an optimization method (dynamic programming) to calculate the optimal power management, determine the optimal control signals, and extract efficient thresholds and rules that can be used in real time. Finally, simulation results for the three strategies (optimal, simple and refined strategy) are shown and discussed.     

Nonlinear tire-road friction control based on tire model parameter identification

A hierarchical control structure is a more suitable structural scheme for integrated chassis control. Generally, this type of structure has two main functions. The upper layer manages global control and force allocation, while the bottom layer allocates realized forces with 4 independent local tire controllers. The way to properly allocate these target forces poses a difficult task for the bottom layer. There are two key problems that require attention: obtaining the nonlinear time-varying coefficient of friction between the tire and different road surfaces and accurately tracking the desired forces from the upper layer. This paper mainly focuses on longitudinal tire-road friction allocation and control strategies that are based on the antilock braking system (ABS). Although it is difficult to precisely measure longitudinal tire-road friction forces for frequently changing road surface conditions, they can be estimated with a real-time measurement of brake force and angular acceleration at the wheels. The Magic Formula model is proposed as the reference model, and its key parameters are identified online using a constrained hybrid genetic algorithm to describe the evolution of tire-road friction with respect to the wheel slip. The desired wheel slip, with respect to the reference tire-road friction force from the top layer, is estimated with the inverse quadratic interpolation method. The tire-road friction controller of the extended anti-lock braking system (Ext-ABS) is designed through use of the nonlinear sliding mode control method. Simulation results indicate that acceptable modifications to changes in road surface conditions and adequate stability can be expected from the proposed control strategy.     

Community Fishery Resources Management on Malalison Island,Philippines: R & D Framework,Interventions, and Policy Implications

In 1991, the Aquaculture Department of the Southeast Asian Fisheries Development Center launched a community-based fishery resources management project on Malalison Island, in central Philippines, to help conserve the country's marine resources and to help the fisherfolk rise above their poverty. The eight-year project integrated various disciplines in biology, economics, sociology, public administration, and engineering in its study of fishery resources and fishing communities and in evolving intervention strategies for resource conservation and management, and for community development. The project's most important accomplishment was the inculcation among the fisherfolk of the importance of resource conservation and management. The most important lesson learned was that an enlightened and empowered fisherfolk could be effective managers and responsible users of fishery resources.     

Valuing Recreation and Amenities at San Diego County Beaches

Abstract

Policymakers and analysts concerned with coastal issues often need economic value information to evaluate policies that affect beach recreation. This paper presents economic values associated with beach recreation in San Diego County generated from a recreation demand model that explains a beach user's choice of which beach to visit. These include estimates of the economic values of a beach day, beach closures, and beach amenities.     

Book review

Recreation: Marine Promise, Proceedings of the National Conference on Marine Recreation Susan H. Andersen, Ed., October 2–4, 1975, Newport Beach, California

Parable Beach: A Primer in Coastal Zone Economics by J. W. Devanney III, G. Ashe, and B. Parkhurst, The MIT Press, 1976, 99 pp.

Marine Recreational Fisheries, Proceedings of the First Annual Marine Recreational Fisheries Symposium Henry Clepper, ed., New Orleans, Louisiana, February 27, 1976.     

Preface and Acknowledgments

Abstract

The term “mitigation”; has been used in connection with habitat losses attributable to federal water projects as early as the Rivers and Harbors Act of 1899 and the Fish and Wildlife Coordination Act of 1934. Most of the current requirements to mitigate habitat losses associated with water development projects apply to wetlands, as they are biologically productive and have been destroyed at an increasing rate during recent years by developers seeking prime land in the coastal zone. A case study of the Port of Coos Bay and the City of North Bend, Oregon, provides an actual experience of estuarine mitigation in a dredging project and an airport fill. The case was developed as part of a larger curriculum research study for seaport management. This article is primarily written as a case with a brief introduction and discussion of mitigation requirements, followed by the text of the case and ending with a series of hypotheses for further research.     

Ecology of bottom ice algae: II. Dynamics, distributions and productivity

Spring blooms of bottom ice algae are a common feature of landfast congelation ice in polar regions. Because ice algae are usually associated with a substrate, their population dynamics can be followed with considerable confidence. Although ice algal dynamics are closely related to irradiance, their dynamics and distributions are influenced by other abiotic and biotic factors. Ice algal abundance varies horizontally over all scales examined. Factors such as grazing and nutrient availability may contribute to local and geographic differences. Loss terms for most sea ice assemblages are largely unquantified. Ice algal biomass is most concentrated near the ice-water interface in spring.Environmental factors affecting ice algal abundance and productivity are considered here, emphasizing recent results from several well-studied sites. Biomass accumulation, growth rates and productivity have been documented for spring blooms of bottom interstitial and sub-ice assemblages. On an areal basis biomass accumulation in bottom ice assemblages can be comparable with planktonic systems. At low ambient temperatures and irradiances average specific growth rates (≤ 0.25 d⁻¹) and production rates (≤ 1.0 mg C mg Chl⁻¹ h⁻¹) for ice algae are low. Current methods of measuring productivity are compared. Results are consistently low but variable with little systematic difference among them. At present, apparent differences in productivity between bottom ice assemblages in the Arctic and Antarctic, or among different antarctic assemblages, are so confounded by methodological and other sources of variability that no firm differences can be detected.     

Habitat characteristics as determinant of the structure and spatial distribution of epibenthic and demersal communities of Le Danois Bank (Cantabrian Sea, N. Spain)

The purpose of this paper is to detect and describe general trends in the spatial distribution of epibenthic and demersal communities of Le Danois Bank (El Cachucho) in relation to the environmental variables that characterize their habitat by means of multivariate ordination. Data were derived from two multidisciplinary surveys carried out in October 2003 and April 2004 included in the ECOMARG project. The surveys were focused on the study of the physical scenario, including both geological (seabed characterization from bathymetry and backscatter data) and hydrographic features, and the different compartments of the benthic fauna (endobenthic, epibenthic, suprabenthic and demersal communities). For the present study, epibenthos and demersal species were sampled using two different gears, a 3.5 m beam trawl and a Porcupine 39/52 type baca otter trawl respectively. The total species richness combining both samplers ascended to 221, including 71 species of fishes, 65 crustaceans, 35 molluscs, 29 echinoderms, 10 cnidarians and 5 sponges.Multivariate methods were used for the study of the characteristics of communities and habitats. Hierarchical cluster analysis was applied to calculate and visualize similarities between samples in terms of species composition. To assess the amount of variation of faunal densities related to a set of eight environmental variables, a redundancy analysis (RDA) was used. The set of environmental variables used were: depth, near-bottom temperature and salinity, sedimentary typology (dry weight percentages of coarse sands, medium and fine sands, silt and organic matter) and seafloor reflectivity. Using the spatial distribution of the ranges of depth and seafloor reflectivity that characterize the habitats of the faunal assemblages we defined the spatial distribution of the different communities.The multivariate analysis of 18 beam-trawl samples and 15 otter trawl samples showed the existence of 4 main assemblages associated with the more characteristic habitats of the area. The Callogorgia–Chimaera community live mainly in the areas at the top of the Bank (425–550 m depth), where the sediment coverage is lower and there exists a high presence of rocky outcrops. The Gryphus–Galeus community were found in the areas at the top of the Bank covered by medium and fine sand sediments with low organic matter content. The Phormosoma–Trachyrincus community live on the sedimentary terraces that characterize the Bank break (550–800 m) and the Pheronema–Deania community occupy all the deeper (800–1050 m) sedimentary grounds of the inner basin.