An optimization principle for deriving nonequilibrium statistical models of Hamiltonian dynamics

A general method for deriving closed reduced models of Hamiltonian dynamical systems is developed using techniques from optimization and statistical estimation. As in standard projection operator methods, a set of resolved variables is selected to capture the slow, macroscopic behavior of the system, and the family of quasi-equilibrium probability densities on phase space corresponding to these resolved variables is employed as a statistical model. The macroscopic dynamics of the mean resolved variables is determined by optimizing over paths of these probability densities. Specifically, a cost function is introduced that quantifies the lack-of-fit of such paths to the underlying microscopic dynamics; it is an ensemble-averaged, squared-norm of the residual that results from submitting a path of trial densities to the Liouville equation. The evolution of the macrostate is estimated by minimizing the time integral of the cost function. The value function for this optimization satisfies the associated Hamilton-Jacobi equation, and it determines the optimal relation between the statistical parameters and the irreversible fluxes of the resolved variables, thereby closing the reduced dynamics. The resulting equations for the macroscopic variables have the generic form of governing equations for nonequilibrium thermodynamics, and they furnish a rational extension of the classical equations of linear irreversible thermodynamics beyond the near-equilibrium regime. In particular, the value function is a thermodynamic potential that extends the classical dissipation function and supplies the nonlinear relation between thermodynamics forces and fluxes

Labour importation and unemployment of local workers in Taiwan

[[abstract]]Since the 1990s the labor market in Chinese Taipei has seen increasing employment of foreign workers vis-à-vis increasing local unemployment. The situation has sparked policy debates and calls for restricting the importation of foreign workers. Do foreign workers take away jobs from domestic workers? To what extent can domestic unemployment be attributed to labor importation? Who are the domestic workers affected by labor importation? These questions were explored using data from the 1996–99 Manpower Utilization Surveys. The study found that on the whole, there is no distinct relationship between labor importation and domestic unemployment. However, foreign labor does have a positive influence on employment for managerial/professional workers and a negative effect for the semi- and less-skilled construction workers. The use of foreign workers seems to affect domestic unemployment in sectors which are foreign labor-intensive sectors such as electronics and construction. Foreign workers do not complement domestic workers in managerial and professional occupations in foreign labor-intensive industries. The complementary effect becomes evident when all industries are considered in the model.[[notice]]補正完畢[[journaltype]]國外[[booktype]]紙本[[countrycodes]]PH