Partitioning strategy for efficient nonlinear finite element dynamic analysis on multiprocessor computers

A computational procedure is presented for the nonlinear dynamic analysis of unsymmetric structures on vector multiprocessor systems. The procedure is based on a novel hierarchical partitioning strategy in which the response of the unsymmetric and antisymmetric response vectors (modes), each obtained by using only a fraction of the degrees of freedom of the original finite element model. The three key elements of the procedure which result in high degree of concurrency throughout the solution process are: (1) mixed (or primitive variable) formulation with independent shape functions for the different fields; (2) operator splitting or restructuring of the discrete equations at each time step to delineate the symmetric and antisymmetric vectors constituting the response; and (3) two level iterative process for generating the response of the structure. An assessment is made of the effectiveness of the procedure on the CRAY X-MP/4 computers

Development of fisheries co-management in Cambodia : a case study and its implications

The livelihoods and food security of many Cambodians depend heavily on inland capture fisheries, so the sustainable management of these fisheries is very important. Notwithstanding, the sustainability of Mekong fisheries is threatened by increasing fishing pressure and habitat modifications. Current management is considered insufficiently capable of controlling levels of exploitation and achieving equitable distribution of the resource, and the Cambodian government is promoting co-management initiatives as a way of addressing these issues. Using an institutional analysis approach, the current performance of co-management in a Mekong mainstream fishery was assessed, and factors limiting success identified. Results suggest that performance and sustainability of co-management are currently constrained by a lack of clearly defined property rights and resource boundaries, a mismatch between resource scale and management initiatives, and an absence of enabling legislation. Furthermore, objectives for management differ between stakeholders and are not well defined overall. While enabling legislation due to come into effect shortly is expected to improve performance and sustainability of co-management, boundary and scale issues will continue to pose challenges to co-management in open systems such as the Mekong mainstream. As a result, calls for innovative solutions, such as a federation of co-management schemes, will continue. In addition, increasing dependence on fishing, and external threats to resources need to be addressed if sustainability is to be improvedFishery management, Inland fisheries, Cambodia,

Continuum modeling of large lattice structures: Status and projections

The status and some recent developments of continuum modeling for large repetitive lattice structures are summarized. Discussion focuses on a number of aspects including definition of an effective substitute continuum; characterization of the continuum model; and the different approaches for generating the properties of the continuum, namely, the constitutive matrix, the matrix of mass densities, and the matrix of thermal coefficients. Also, a simple approach is presented for generating the continuum properties. The approach can be used to generate analytic and/or numerical values of the continuum properties

Socioeconomics and values of resources in great Lake-Tonle Sap and Mekong-Bassac area : results from a sample survey in Kampong Chhnang, Siem Reap and Kandal provinces, Cambodia

Socioeconomics aspects, Fishery economics, Cambodia,