Schell D.J.,National Renewable Energy Laboratory |
Dowe N.,National Renewable Energy Laboratory |
Chapeaux A.,P2 Science |
Nelson R.S.,National Renewable Energy Laboratory |
Jennings E.W.,National Renewable Energy Laboratory
Accurate mass balance and conversion data from integrated operation is needed to fully elucidate the economics of biofuel production processes. This study explored integrated conversion of corn stover to ethanol and highlights techniques for accurate yield calculations. Acid pretreated corn stover (PCS) produced in a pilot-scale reactor was enzymatically hydrolyzed and the resulting sugars were fermented to ethanol by the glucose-xylose fermenting bacteria, Zymomonas mobilis 8b. The calculations presented here account for high solids operation and oligomeric sugars produced during pretreatment, enzymatic hydrolysis, and fermentation, which, if not accounted for, leads to overestimating ethanol yields. The calculations are illustrated for enzymatic hydrolysis and fermentation of PCS at 17.5% and 20.0% total solids achieving 80.1% and 77.9% conversion of cellulose and xylan to ethanol and ethanol titers of 63 g/L and 69 g/L, respectively. These procedures will be employed in the future and the resulting information used for techno-economic analysis. © 2016 Elsevier Ltd. Source
Ho I.W.-H.,Hong Kong Polytechnic University |
Lam P.P.,P2 Science |
Chong P.H.J.,Nanyang Technological University |
Liew S.C.,Chinese University of Hong Kong
IEEE Transactions on Mobile Computing
There has been an increasing interest in deploying wireless mesh networks (WMNs) for communication and video surveillance purposes thanks to its low cost and ease of deployment. It is well known that a major drawback of WMN is multihop bandwidth degradation, which is primarily caused by contention and radio interference. The use of mesh nodes with multiple radios and channels has been regarded as a straightforward solution to the problem in the research community. However, we demonstrate in this paper through real-world experiments that such an approach cannot resolve the multihop TCP throughput degradation problem in IEEE 802.11n mesh networks. With extensive experimentation, we verify that the degradation is principally caused by the increase in TCP Round-Trip Time (RTT) when the number of hops increases. TCP throughput is fundamentally limited inversely by the RTT. We find that the multihop TCP throughput (up to five hops) when using 802.11n is no better than when using 802.11a, despite the much higher data rate 802.11n. We attempt to use multiple parallel TCP connections as a remedy to the problem, and it turns out that the wireless bandwidth can be fully utilized with a sufficient number of parallel streams. In general, our results give a key message that TCP tuning (e.g., setting the correct TCP buffers and use of parallel streams) is of paramount importance in high-bandwidth multihop wireless mesh networks that employ the latest wireless standards. These tuning techniques have to be implemented into commercial products to fully leverage the ever advancing wireless technologies to support the growing demand of multihop communications in wireless mesh networks. © 2014 IEEE. Source
Popova O.,Russian Academy of Sciences |
Borovicka J.,Czech Republic Astronomical Institute |
Hartmann W.K.,Planetary Science Institute |
Spurny P.,Czech Republic Astronomical Institute |
And 3 more authors.
Meteoritics and Planetary Science
We have assembled data on 13 cases of meteorite falls with accurate tracking data on atmospheric passage. In all cases, we estimate the bulk strength of the object corresponding to its earliest observed or inferred fragmentation in the high atmosphere, and can compare these values with measured strengths of meteorites in the taxonomic class for that fall. In all 13 cases, the strength corresponding to earliest observed or inferred fragmentation is much less than the compressive or tensile strength reported for that class of stony meteorites. Bulk strengths upon atmospheric entry of these bodies are shown to be very low, 0.1 to approximately 1MPa on first breakup, and maximal strength on breakup as 1-10MPa corresponding to weak and "crumbly" objects, whereas measured average tensile strength of the similar meteorite classes is about 30MPa. We find a more random relation between bulk sample strength and sample mass than is suggested by a commonly used empirical power law. We estimate bulk strengths on entry being characteristically of the order of 10-1-10-2 times the tensile strengths of recovered samples. We conclude that pre-entry, meter-scale interplanetary meteoroids are typically highly fractured or in some cases rubbly in texture, presumably as a result of their parent bodies' collisional history, and can break up under stresses of a few megapascals. The weakness of some carbonaceous objects may result from very porous primordial accretional structures, more than fractures. These conclusions have implications for future asteroid missions, sample extraction, and asteroid hazard mitigation. © The Meteoritical Society, 2011. Source
News Article | April 6, 2014
P2 Science Inc., a New Haven, Conn.-based specialty chemical company, raised $1m in funding. Backers included Connecticut Innovations (CI), which made a $500k investment through its Eli Whitney Equity Fund, and Elm Street Ventures. The company intends to use the funds for additional partner and customer commitments. Led by Neil Burns, chief executive officer, P2 Science produces consumer and industrial product ingredients from soy, canola, palm and other oils, as well as wood, grass and other plant-based feedstocks. In addition to new proprietary ingredients, the company’s products will include vegetable-based equivalents of chemical ingredients previously only available from petrochemical sources. It has begun manufacturing product ingredients using a pilot reactor installed at its lab in Science Park.
News Article | March 25, 2013
P2 Science, Inc., a New Haven, Conn.-based specialty chemical company developing a novel class of surfactants, raised an $200k in funding from Connecticut Innovations. Led by CEO Neil Burns and CSO Patrick Foley, P2 Science has developed a novel chemical process, known as hybrid ozonolysis, that enables the conversion of biomass, including vegetable oils, into aldehydes for use in fragrances and flavors and into di-acids for use in cosmetics and polymers. The products, derived from soy, canola, palm and other oils, will replace chemical ingredients previously only available from petrochemical sources, thus meeting the demand for “green” alternatives in the marketplace. The company has licensed some of its intellectual property from Yale University and has established a collaborative relationship with the University of Alberta. P2 Science had received pre-seed funding of $150k from CI in 2012 (read here). Other investors include Elm Street Ventures.