Renewable 1,4-Butanediol

The purpose of this project is to design a commercial-scale facility to produce 50 million pounds per year of 1,4-butanediol (BDO) from a renewable feedstock. A genetically engineered strain of Escherichia coli developed by Genomatica, Inc. will metabolize a molasses feed, delivered from an adjacent sugar and ethanol facility, into BDO. The BDO product purity and quality must meet or exceed current commercial requirements for polymer-grade material to be acceptable to prospective customers. The innovative technology to produce environmentally-friendly BDO will convert biomass-derived and renewable feedstocks in fewer steps than traditional petrochemical routes, with no toxic byproducts and minimal greenhouse gas emissions. Our BDO plant will be built in São Paulo, Brazil. This location was chosen due to its proximity to our sister sugar and ethanol facility. Despite the need to stop production for three months in mid-December through mid-March during the rainy season, when our sister plant will cease its molasses production, we determined that the low cost per amount of sugar from the Brazilian molasses will outweigh the ability to run year-round in a corn-based facility in the Midwestern United States. To account for the downtime associated with the rainy season, our facility has included extra molasses storage capacity to extend production for an additional month after our sister facility shuts down. We also anticipate 10 days of downtime due to maintenance and cleaning, which will result in about 290 days of full-scale facility operation. An economic analysis of our design demonstrated profitability after the first year of operation. Our feed materials, corn steep liquor, oleic acid, process water, and molasses, will cost us a total of about $200 per ton of BDO produced. But our vinasse co-product, which will be sold back to our sister sugar and ethanol plant for fertilizer, will result in additional revenues of$190 per ton of BDO produced. The selling price of the vinasse is discounted by 70% of the current fertilizer market price since we are selling it back to our sister facility, in return for discounted molasses and electricity. The direct permanent investment of the plant will be about $10.5 million and startup costs will be about$1.5 million, which results in a total permanent investment of $13.5 million. The net present value (NPV) of our facility with 15 years of production is$283 million and the internal rate of return (IRR) is 157%. We intend to sell our 99% pure BDO at $2,420 per ton produced, which will result in revenues of$72.5 million per year based on our commercial-scale production of 8,600 pounds of BDO per hour. Due to the profitability of our design, we will be able to sell our BDO at the low end of the U.S. market price range of $2,420 –$2,840 per ton, as was reported in the third quarter of 2010. Future research may need to be conducted to find out if additional equipment is needed in the actual plant, or if we were too optimistic on our pricing for the raw materials and utilities

Development of Possible Go-Around Criteria for Transport Aircraft

This paper adds data to help with the development of possible go-around criteria for transport category aircraft. Presently, airline procedures state that pilots make a go-around decision using multiple criteria at 1000 or 500 ft above the ground, or so-called gates. An experiment conducted on three level-D full-flight simulators investigated the conditions from which pilots cannot successfully recover from an unstable approach and make a normal landing. In addition, pilots' perceptions of risk under these various unstable approach conditions and resulting landings were assessed. Six crews, comprised of a captain and a first officer from the same airline, participated in each simulator. Both the captain and the first officer flew approaches and landings from 55 different initial conditions with varying gate heights, localizer deviations, glideslope deviations, reference-speed deviations, and rate of descents. The initial condition at the starting gate mainly affected longitudinal touchdown deviation and rate of descent at touchdown, with reference-speed deviation having the most significant effect. Results show little difference in touchdown performance for conditions from the 300-ft and 500-ft gates. Conditions at the 100-ft gate introduced significant differences in touchdown performance. Reference-speed and localizer deviation at the starting gate had the strongest influences on perceived risk and go-around decision. In line with other studies, these findings suggest that a 300-ft go-around gate might be acceptable. More research is required to investigate the effects of environmental and runway variables before possible go-around criteria for transport category aircraft can be defined

Pilot Evaluation of Proposed Go-Around Criteria for Transport Category Aircraft

The primary objective of this study was to capture pilot feedback and decision-making with regard to proposed, hypothetical, go-around criteria that were developed based on previous research. A secondary objective of the study was to assess crew members' awareness of the aircraft state on approach. An experiment was conducted using Boeing 737-800 and Airbus A330-200 level D full-flight simulators, in which pilots flew multiple approaches which were on the borderline of the proposed go-around criteria at 300 ft. Pilots were instructed that they could either execute a go-around or land the airplane on each run, forcing a decision for the borderline cases at 300 ft. Pilots were instructed to go around if the aircraft was outside of the go-around criteria at 300 ft or if either pilot was uncomfortable with the approach. The results revealed that: 1) the most important factors which drove go-around decision-making during the experiment were airspeed and localizer deviation, 2) the objective data suggested that the 300-ft gate is viable, although many pilots were still uncomfortable with that gate height; perhaps more emphasis on checking stability at 1,000 ft and 500 ft would make more pilots comfortable with the 300-ft go-around gate, 3) allowing for momentary deviations should be considered, and 4) the acceptability of the criteria is highly dependent on given pilot's risk tolerance. Overall, the proposed criteria performed well, and most pilots would find the criteria acceptable with some minor adjustments

Multi-Nation WPT Demonstration Experiments

A project originating with Georgia Institute of Technology is described in which the International Space Station (ISS) serves as an experimental platform for the relay of energy from space to earth. The multi-nation test will feature the transmission of small amounts of solar-generated electric power from the ISS using millimeter waves, for the purposes of collecting atmospheric propagation data and testing technologies for power beaming, aiming, and reception. This initiative represents an early first-step towards installation of a global Space Solar Power Grid emphasizing international collaboration, synergy with the terrestrial energy industry and with retail power beaming markets. The technical paper on which this visualization is based is listed in References below. Advisors: Prof. N. Komerath, Prof. D. Flournoy, Kyle Perkins (Designer) Five-Nation - Broadband from Space Journal on Vimeo

Comparison of Endothelial Cell Loss by Specular Microscopy between Phacoemulsification and Manual Small-Incision Cataract Surgery

Aim: To compare the endothelial cell loss between phacoemulsification and manual small‑incision cataract surgery (SICS). Endothelial cell loss was also compared in phacoemulsification group by temporal clear corneal incision (CCI) and by superior scleral incision (SI) technique.Materials and Methods: A total of 200 eyes of 200 patients were included in the study. Cases were randomly divided into two equal groups. Group A had undergone phacoemulsification and Group B had under gone manual SICS. In Group A 50 cases were performed by temporal CCI and remaining 50 cases were performed by superior SI technique. Endothelial cell count was evaluated by using a noncontact specular microscope.Results: Mean endothelial cell loss (cells/mm2) in Group A was 307.80 (12.33%), 397.79 (15.93%), and 421.69 (16.89%) on 1 week, 6 week, and 3 month postoperative period, respectively. In Group B, it was 270.86 (10.63%), 385.22 (15.12%), and 413.68 (16.24%) on 1 week, 6 week, and 3 month postoperative period, respectively. There was no clinical and statistically significant difference (P > 0.05) between the two groups. The mean endothelial cell loss in Group A by CCI was 340.68 (13.61%), 427.80 (17.08%), and 448.70 (17.92%) and by SI was 274.92 (11.05%), 367.78 (14.78%), and 394.68 (15.83%) on 1 week, 6 week, and 3 month postoperative period respectively. There was statistically significant difference in endothelial cell loss at 1 week (P < 0.05) but it was not statistically significant on 6 week and 3 month postoperatively (P > 0.05).Conclusion: There was no clinically or statistically significant difference in endothelial cell loss or visual acuity between phacoemulsification and manual SICS at 3 month postoperative period.Keywords: Endothelial cell count, manual small incision cataract surgery, phacoemulsification, specular microscop

A Simulation-Based Framework for Structural Loads Assessment during Dynamic Maneuvers

Federal Aviation Regulations pertaining to structural integrity are key drivers in aircraft design and certification, and often involve critical loads occurring during dynamic maneuvers. In the context of increasing costs of testing and the general trend towards parametric design, there is a need for a more thorough consideration of such dynamic load cases earlier in the design process. In this work, a simulation framework is introduced to assess structural requirements stemming from such dynamic load conditions. Relevant aspects of the dynamics of the aircraft, the control system, and the pilot are modeled in order to simulate the maneuver and thereafter obtain inertial and aerodynamic loads on the empennage during the simulated maneuver. The loads are then translated into structural shear forces and bending moments through structural post-processing routines. This approach is demonstrated for the case of a representative business jet during the checked pitch maneuver. The analyses are repeated for three weight conditions and over the flight envelope for the aircraft from which the load cases resulting in the most constraining loads are determined

Provisional Restorative Materials In Fixed Prosthodontics: A Comprehensive Review

ABSTRACT The need for accurate provisional restorations has led to the introduction of a multitude of materials for the same, with considerable variation in physical, chemical and biologic properties. Polymethylmethacrylatebased materials have long dominated the arena of provisional restorative materials, but the advent of newer resin based materials with superior handling characteristics has broadened the spectrum of temporization. While the choice of a particular material, or technique rests solely with the clinician, and varies as per patient needs; an insight has been provided here, dissecting the merits and demerits of each material, with the sole aim of affording a better understanding and improving clinical performance