Archive for September, 2008
Effect of Reaction Temperature on The performance of Thermal Swing Sorption Enhanced Reaction Process for Simultaneous Production of Fuel Cell Grade H2 and Compressed CO2 from Synthesis Gas
A novel cyclic thermal swing sorption enhanced reaction (TSSER) process concept was recently proposed for simultaneous production of fuel-cell grade H2 and compressed CO2 from a synthesis gas containing CO and H2O. The process carried out the catalytic water gas shift (WGS) reaction (CO + H2O ↔ CO2 + H2) with simultaneous removal of CO2 from the reaction zone by a reversible, hydrophobic, CO2 selective chemisorbent in order to circumvent the thermodynamic limitation of the WGS reaction and enhance the rate of the forward reaction. The chemisorbent was periodically regenerated using the principles of thermal swing adsorption by purging the sorber-reactor with super heated steam at different pressures and temperatures. Several intermediate process steps were employed to produce a pure and compressed CO2 by-product during the thermal desorption process.
New experimental data are reported to demonstrate that high purity H2 can be directly produced by sorption-enhanced water gas shift (WGS) reaction using synthesis gas (CO + H2O) as sorber-reactor feed gas. An admixture of a commercial WGS catalyst and a proprietary CO2 chemisorbent (K2CO3 promoted hydrotalcite or Na2O promoted alumina) was used in the sorber-reactor for removal of CO2, the WGS reaction by-product, from the reaction zone. The promoted alumina was found to be a superior CO2 chemisorbent for this application because (a) it could directly produce a fuel-cell grade H2 product (<10-20 ppm CO) at reaction temperatures of 200 and 400 oC, and (b) it produced ~ 45.6% more high purity H2 product per unit amount of sorbent than the promoted hydrotalcite at 400 oC. Furthermore, the specific fuel-cell grade H2 productivity by the promoted alumina at a reaction temperature of 200 oC was ~ 3.6 times larger than that at 400 oC. These striking differences in the performance of the two CO2 chemisorbents were caused by the differences in their CO2 sorption equilibria and kinetics.
Differences in territory quality and subsequent behavioral changes of male beaugregory damselfish, Stegastes leucostictus
When territory quality can vary over time, natural selection should have favored animals with behavioral flexibility in order to modulate the cost of defense in accordance with territory quality. This requires assessment of the territory followed by appropriate types and intensities of behavior. We examined this hypothesis using male beaugregory damselfish by enhancing territory quality using artificial breeding sites and comparing their behavior to males on natural sites. Males on artificial sites reproduce at higher levels than males on natural sites. In Experiment 1, our aim was to determine if a behavioral syndrome existed between courtship and aggressive behaviors across different quality sites. We found that behaviors were correlated on natural sites, but not artificial. When changes in territory quality occurred, courtship and aggression were not correlated and males had high levels of behaviors on high quality (artificial) territories. These results indicate that males assess their current territories and adjust behaviors accordingly. In Experiment 2, the value of reproduction was explored by giving males a choice between courting a female (potential reproduction) or attacking an egg predator (potential loss of eggs). A significant interaction was seen between the territory type and the stimuli: males on natural sites spent more time courting females and less time defending, while males on artificial sites behaved oppositely. Thus, males defending low quality territories invest in courtship while devaluing the relative importance of an egg predator while males defending high quality sites invest more in repelling the egg predator than attracting the female.
Syllables are chunks in Mandarin, not in Spanish or English
Uncertainty still characterizes the role of syllables in language production within and across languages. We examined the hypotheses that syllables channel phonological encoding in European languages, perhaps more strongly in Romance than in Germanic languages, and that syllables are themselves primary encoding units in Chinese. We report parallel disyllable word-pair recitation experiments in three languages using variants of a classic design in which first syllable alignment is crossed with phonological overlap (e.g., aligned CVC: ham.let ham.per; unaligned CV ma.lice mag.net). › Continue reading
Recognizing The Enemy: Combining Reinforcement Learning with Strategy Selection using Case-Based Reasoning
This paper presents CBRetaliate, an agent that combines Case-Based Reasoning (CBR) and Reinforcement Learning (RL) algorithms. Unlike most previous work where RL is used to improve accuracy in the action selection process, CBRetaliate uses CBR to allow RL to respond more quickly to changing conditions. CBRetaliate combines two key features: it uses a time window to compute similarity and stores and reuses complete Q-tables for continuous problem solving.We demonstrate CBRetaliate on a team-based first-person shooter game, where our combined CBR+RL approach adapts quicker to changing tactics by an opponent than standalone RL.