Agent‐based task representation and processing in pervasive computing environment

Abstract

It is an effective approach to adopt software agent in pervasive computing (Per‐Com) environment. Meanwhile, task execution is the key problem which is affected directly by task representation method in Per‐Com environment. The task of agent in Per‐Com environment is dynamic and changeful, so the task representation should be flexible and agent‐oriented. However, most of the existing task representation methods cannot present task relationship clearly and lack unified format, which leads to a drawback that the corresponding task processing efficiency is not satisfying. In this paper, firstly, an agent‐based Per‐Com architecture is presented in which the agent is endowed with certain role. Secondly, through analyzing task relationship, an agent role based task relationship tree (TRT) model and an XML‐based agent task representation method are proposed. Thirdly, based on TRT, an agent task decomposing and online multi‐agent scheduling algorithm are presented to solve time‐optimal problems. Meanwhile, a load balancing strategy based on probability is proposed to increase agent utilization. Finally, a prototype of an application on traffic monitoring is presented. The results of evaluation indicate that the architecture is feasible and the simulation tests of time performance indicate that the proposed TRT‐based task processing methods have a better performance than others. Copyright © 2009 John Wiley & Sons, Ltd.

Synthetic Formatotrophs for One‐Carbon Biorefinery

“…Studies on the development of formatotrophic E. coli strains up to date can be summarized as follows. To enable E. coli to utilize FA only or FA and CO 2 , various synthetic FA assimilation pathways ( Table 1 ) were constructed by the development of novel enzymes, [ 39 ] enzyme engineering, [ 40 ] and reconstruction of FA assimilation pathways ( Figure ). [ 28–31 ] The synthetic FA assimilation pathways lead to the biosynthesis of one of the three core metabolites, acetyl‐CoA, dihydroxyacetone phosphate (DHAP), and pyruvate, from FA only or FA and CO 2 ( Figure ).…”

“…In another study, the synthetic acetyl‐CoA (SACA) pathway [ 40 ] was introduced in E. coli to produce one acetyl‐CoA molecule from two FA molecules using two ATP and two NADH molecules (Figure 2b and Table 1). In this pathway, FALD is first synthesized from FA by Acs and Acdh, similar to the Fls pathway.…”

“…This synthetic FA assimilation pathway is promising because the enzymes employed for FA assimilation were selected from native formatotrophs, which possess much higher enzyme activities [ 45 ] than those of de novo enzymes. [ 39,40 ] In addition, the theoretical maximum biomass yield by this synthetic FA assimilation pathway (5.7 gDCW mol of FA −1 ) was calculated to be the highest compared to those of other native and synthetic FA assimilation pathways (CBB cycle, 4.8 gDCW mol of FA −1 ; Fls pathway, 4.9 gDCW mol of FA −1 ; serine cycle, 5 gDCW mol of FA −1 ) based on flux balance analysis using E. coli metabolic model. [ 41 ] Most importantly, pyruvate can be easily converted to diverse chemicals through the native metabolic pathways in E. coli .…”