Fishing the line depends on reserve benefits, individual losing at boundary and movement preference

Whether fishing around the marine reserve edge can enhance harvested yields is an important issue in fisheries management. To solve the conundrum is difficult because of the lack of a matched boundary condition. Here, we derive a new boundary condition by considering individual losing at habitat boundaries. With the suitable boundary condition, our results suggest that individuals with high growth rate inside but low growth rate outside the reserve and high movement preference to a large marine reserve boundary can enhance yields benefits from fishing around the marine reserve edge. The findings provide theoretical cautions for fishing near some new reserves in which population growth rate might be low. Moreover, our boundary condition is general enough for the universal phenomenon of losing individual at habitat boundaries such as being applied into classic theories in refuge design to explain some previous counter-intuitive phenomena more reasonably.

Possibility of Using Fourier’s Differential Equation in Cooling Process of Meat Steaks

Summary: In this paper, based on derived differential equation for the heat transfer and a suitable boundary condition (equation of heat exchange), the appropriate model of cooling of meat stakes in the form of a flat plate is set up. By using theory of similarity, Fourier and Biot criterion is defined, which allowed setting criterial equation of temperature field which included an unnamed temperature and geometric criterion. For solving the obtained criterial equation, existing diagrams of temperature functions were utilized, which were specified by analytical method for the core, the surface and the interior of the observed model. The proposed model is used for analytical solving of a number of practical problems in the cooling process of meat steaks in a gaseous environment. Particular focus has been on the temperature of the surface and core of steak as well as ambient temperature and cooling time. Also, it was shown that proposed model can be used to define temperatures or temperature field along the thickness of steak, depending on the distance from the central plane. Special possibility of applying the model is for the case of preventing freezing steaks, when their temperature is maintained within specified limits.

DQM to Simulate 3D Vortex Structure of Cuboid Cavity Driven Flow

The vortex structure of lid-driven flow in a cuboid cavity with one or a pair of moving lids is numerated using the differential quadrature method (DQM). According to the characteristics of cavity driven flow, the dimensionless governing equations and its boundary conditions used to describe the flow are established. Based on a non-staggered grid technology, the polynomial-based DQM is combined with the SIMPLE strategy to solve three-dimensional (3D) cavity driven flow. The suitable boundary condition for pressure correction equation on a non-staggered system is implemented and the continuity equation on the boundary is enforced to be satisfied. The 3D vortex structure distributions in a cuboid cavity are obtained for different Reynolds numbers and different driving modes. The analysis shows that the DQM is very suitable for the simulation of 3D vortex structure in a cavity.

PATH-INTEGRAL FORMULATION OF CASIMIR EFFECTS IN SUPERSYMMETRIC QUANTUM ELECTRODYNAMICS

The path-integral method of calculating the Casimir energy between two parallel conducting plates is developed within the framework of supersymmetric quantum electrodynamics at vanishing temperature as well as at finite temperature. The choice of the suitable boundary condition for the photino on the plates is argued and the physically acceptable condition is adopted which eventually breaks the supersymmetry. The photino mass term is introduced in the Lagrangian and the photino mass dependence of the Casimir energy and pressure is fully investigated.

Non-equilibrium flow through a nozzle

Vibrationally relaxing flow through a nozzle is examined in the case when the amount of energy in the lagging mode is small. It is shown that there exists a ‘boundary-layer’ region in which relatively large departures from equilibrium occur. The position of this region is given by the type of criterion that has previously been used to predict the onset of ‘freezing’. An analytical solution for the distribution of the vibrational energy in the nozzle is obtained for a particular nozzle geometry, and an expression for the final asymptotic ‘frozen’ value of the vibrational energy far downstream is found. This asymptotic solution can be obtained from conditions at the ‘freezing’ point provided a suitable boundary condition is applied there.