Stability and moment bounds under utility-maximising service allocations: Finite and infinite networks

We study networks of interacting queues governed by utility-maximising service-rate allocations in both discrete and continuous time. For finite networks we establish stability and some steady-state moment bounds under natural conditions and rather weak assumptions on utility functions. These results are obtained using direct applications of Lyapunov–Foster-type criteria, and apply to a wide class of systems, including those for which fluid-limit-based approaches are not applicable. We then establish stability and some steady-state moment bounds for two classes of infinite networks, with single-hop and multi-hop message routes. These results are proved by considering the infinite systems as limits of their truncated finite versions. The uniform moment bounds for the finite networks play a key role in these limit transitions.

Probing the Tz=−3/2 nuclei via magnetic moment measurements

The neutron-deficient region of the nuclear chart provides unique opportunities to study several important effects near the proton-drip line pertaining to nuclear structure and nuclear astrophysics.The present article focuses on nuclei with isospin Tz=−3/2 in terms of the spin polarization and the ground state magnetic moment. An experiment on measuring the ground state moment pf 35K by employing the β-NMR technique leads to several interesting results that pose challenging questions to theory.

Transition process of abrupt climate change based on global sea surface temperature over the past century

A new detection method has been proposed to study the transition process of abrupt climate change. With this method, the climate system transiting from one stable state to another can be verified clearly. By applying this method to the global sea surface temperature over the past century, several climate changes and their processes are detected, including the start state (moment), persist time, and end state (moment). According to the spatial distribution, the locations of climate changes mainly have occurred in the Indian Ocean and western Pacific before the middle twentieth century, in the 1970s in the equatorial middle-eastern Pacific, and in the middle and southern Pacific since the end of the twentieth century. In addition, the quantitative relationship between the transition process parameters is verified in theory and practice: (1) the relationship between the rate and stability parameters is linear, and (2) the relationship between the rate and change amplitude parameters is quadratic.

Transition process of abrupt climate change based on global sea surface temperature over the past century

We propose a new concept of abrupt climate change transition and create a novel detection method to identify the transition process. With this method, how the climate system transits from one stable state to another could be verified clearly. By applying this method to the global sea surface temperature data over the past century, several climate change processes are detected, including their starting state (moment), persist time, and ending state (moment) etc. According to the spatial distributions, the locations of climate changes mainly occurred in Indian ocean and western Pacific before the middle twentieth century, while the climate changes in 1970s located in equatorial middle-eastern Pacific, and the climate changes happened in the middle and southern Pacific since the end twentieth century. In addition, an quantitative relationship among the transition process parameters has been exposed in theory and practice, which the relationship between the rate and stability parameters is linear, and the relationship between the rate and change amplitude parameters is quadratic.

Optimization Model and Algorithm in Microbial Continuous Fermentation Process

In this paper, a nonlinear dynamical system is proposed to describe glycerol bioconversion to 1,3-propanediol (1,3-PD) in continuous fermentation process. Some important properties of the system are then discussed. To maximize the concentration of 1,3-PD at the steady-state moment, an optimization model by taking the concentration of glycerol in the feed flow and the dilution rate as optimization variables is presented. Finally, an improved Particle Swarm Optimization (PSO) algorithm is developed to seek the optimal solution. Numerical results show that the concentration of 1,3-PD at the steady-state moment is increased considerably.