Simulation evaluation of a low-altitude helicopter flight guidance system adapted for a helmet-mounted display

A computer aiding concept for low-altitude helicopter flight was developed and evaluated in a real-time piloted simulation. The concept included an optimal control trajectory-generation algorithm based upon dynamic programming and a helmet-mounted display (HMD) presentation of a pathway-in-the-sky, a phantom aircraft, and flight-path vector/predictor guidance symbology. The trajectory-generation algorithm uses knowledge of the global mission requirements, a digital terrain map, aircraft performance capabilities, and advanced navigation information to determine a trajectory between mission way points that seeks valleys to minimize threat exposure. The pilot evaluation was conducted at NASA ARC moving base Vertical Motion Simulator (VMS) by pilots representing NASA, the U.S. Army, the Air Force, and the helicopter industry. The pilots manually tracked the trajectory generated by the algorithm utilizing the HMD symbology. The pilots were able to satisfactorily perform the tracking tasks while maintaining a high degree of awareness of the outside world

AC Power Monitoring System Provides Individual Circuit Energy Consumption Data

Motivated by high energy costs, people and organizations want to cut back on their energy consumption. However, the only feedback consumers typically receive is a monthly bill listing their total electricity usage (in kWh). Some companies have begun developing systems that allow households and organizations to monitor their energy usage for individual circuits. Available systems are expensive so a CU engineering senior design team has designed, fabricated, and tested a system for use at Cedarville University. The AC power monitoring system has the ability to measure energy consumption for each individual circuit in the breaker panel, store the data, and then provide the user with visual feedback on energy usage behavior. The basic system provides the proof of concept for future senior design teams. After more testing is completed, further development of this product will be needed by other senior design teams. Eventually, this energy monitoring system could be expanded to include larger loads such as HVAC systems and refrigeration units. It is also envisioned that future projects might be able to provide the user with suggestions for changing and improving energy usage behavior. Failure prediction of equipment on individual circuits could also stem from this initial project. For this project, it has been clearly shown that the concept is feasible, expandable, and cost-effective

AC Power Monitoring System

Motivated by high energy costs, people and organizations want to cut back on their energy consumption. However, the only feedback consumers typically receive is a monthly bill listing their total electricity usage (in kWh). Some companies have begun developing systems that allow households and organizations to monitor their energy usage for individual circuits. Available systems are expensive so a CU engineering senior design team has designed, fabricated, and tested a system for use at Cedarville University. The AC power monitoring system has the ability to measure energy consumption for each individual circuit in the breaker panel, store the data, and then provide the user with visual feedback on energy usage behavior. The basic system provides the proof of concept for future senior design teams. After more testing is completed, further development of this product will be needed by other senior design teams. Eventually, this energy monitoring system could be expanded to include larger loads such as HVAC systems and refrigeration units. It is also envisioned that future projects might be able to provide the user with suggestions for changing and improving energy usage behavior. Failure prediction of equipment on individual circuits could also stem from this initial project. For this project, it has been clearly shown that the concept is feasible, expandable, and cost-effective

Design and test of a small single stage turbine

http://www.archive.org/details/designtestofsmal00dearU.S. Navy (U.S.N.) authors

A comparison of A-level performance in economics and business studies: how much more difficult is economics?

This paper uses ALIS data to compare academic performance in two subjects often viewed as relatively close substitutes for one another at A-level. The important role of GCSE achievement is confirmed for both subjects. There is evidence of strong gender effects and variation in outcomes across Examination Boards. A counterfactual exercise suggests that if the sample of Business Studies candidates had studied Economics nearly 40% of those who obtained a grade C or better in the former subject would not have done so in the latter. The opposite exercise uggests that 12% more Economics candidates would have achieved a grade C or better if they had taken Business Studies. In order to render a Business Studies A-level grade comparable to an Economics one in terms of relative difficulty, we estimate that a downward adjustment of 1.5 UCAS points should be applied to the former subject. This adjustment is lower than that suggested by correction factors based on conventional subject pair analysis for these two subjects

Climatic variability during the last millennium in Western Iceland from lake sediment records

The aim of this research was to create a decadal-scale terrestrial quantitative palaeoclimate record for NW Iceland from lake sediments for the last millennium. Geochemical, stable isotope and chironomid reconstructions were obtained from a lake sequence constrained by tephra deposits on the Snæfellsnes peninsula, western Iceland. Obtaining a quantitative record proved problematic, but the qualitative chironomid record showed clear trends associated with past summer temperatures, and the sedimentological records provided evidence for past changes in precipitation, mediated through catchment soil in-wash. When the full range of chronological uncertainty is considered, four clear phases of climatic conditions were identified: (1) a relatively warm phase between AD 1020 and 1310; (2) a relatively stable period between AD 1310 and 1510, cooler than the preceding period but still notably warmer than the second half of the millennium; (3) a consistent reduction of temperatures between AD 1560 and 1810, with the coolest period between AD 1680 and 1810; and (4) AD 1840–2000 has temperatures mainly warmer than in the preceding two centuries, with a rising trend and increased variability from c. AD 1900 onwards. The reconstructions show clearly that the first half of the millennium experienced warmer climatic conditions than the second half, with a return to the warmer climate only occurring in the last c. 100 years. Much of the variability of the chironomid record can be linked to changes in the North Atlantic Oscillation (NAO). The reconstructions presented can track low-frequency and long-term trends effectively and consistently but high-resolution and calibrated quantitative records remain more of a challenge – not just in finding optimal sedimentary deposits but also in finding the most reliable proxy. It is this that presents the real challenge for Holocene climate reconstruction from this key area of the North Atlantic. Keywords : iceland, palaeolimnology, chironomids, little ice age, medieval climate anomaly, north atlantic oscillatio

A 10-year experience of infection following carotid endarterectomy with patch angioplasty

ObjectiveAlthough infection following carotid endarterectomy is rare, consequences of this seldom seen complication can be devastating. Polyester, polytetrafluoroethylene (PTFE), and vein patches have all been used by many institutions for patch angioplasty, each with reported cases of infection following surgery. Our institution has preferentially used PTFE for the majority of cases, and here, we report our experience with postoperative infection following endarterectomy over the last decade.MethodsFrom January 2000 through July 2009, we treated infections following carotid endarterectomy in 25 patients.ResultsOf the 25 patients undergoing treatment for postoperative infection, 21 had PTFE patches placed during the initial surgery. The remaining four consisted of two polyester patches and two bovine pericardial patches. Twenty-three of the 25 initial endarterectomies were performed at our institution, and the other two were referrals. The majority of cases (56%) were due to gram-positive organisms, with only two cases being polymicrobial. The interval from the original surgery to clinical presentation ranged from 7 days to 85 months, with 20 patients (80%) presenting within 60 days of the first operation. Thirteen patients underwent incision and drainage with antibiotics, and 12 patients underwent definitive surgical treatment. Four received patch excision with vein patch angioplasty, four received patch excision with vein interposition, and four received sternocleidomastoid flaps. The 30-day stroke rate was 8%, and the freedom from recurrent infection was 100% at a mean follow-up of 32 months.ConclusionInfection following carotid endarterectomy occurs <1% of the time; however, the potential for morbidity is significant. Our results show that most infections following PTFE patch angioplasty occur in the early postoperative period (<60 days) and that simple drainage with antibiotics may be an adequate form of treatment in select cases

Design and flight evaluation of an integrated navigation and near-terrain helicopter guidance system for night-time and adverse weather operations

NASA and the U.S. Army have designed, developed, and flight evaluated a Computer Aiding for Low Altitude Helicopter Flight (CALAHF) guidance system. This system provides guidance to the pilot for near terrain covert helicopter operations. It automates the processing of precision navigation information, helicopter mission requirements, and terrain flight guidance. The automation is presented to the pilot through symbology on a helmet-mounted display. The symbology is a 'pilot-centered' design which preserves pilot flexibility and authority over the CALAHF system's automation. An extensive flight evaluation of the system has been conducted using the U.S. Army's NUH-60 STAR (Systems Testbed for Avionics Research) research helicopter. The evaluations were flown over a multiwaypoint helicopter mission in rugged mountainous terrain, at terrain clearance altitudes from 300 to 125 ft and airspeeds from 40 to 110 knots. The results of these evaluations showed that the pilots could precisely follow the automation symbology while maintaining a high degree of situational awareness

E-learning as a tool for knowledge transfer through traditional and independent study at two UK higher educational institutes: a case study

Much has been made of the advances in computer aided learning activities. Websites, virtual campus, the increased use of Web CT and chat rooms and further advances in the use of WebCT are becoming more commonplace in UK universities. This paper looks for ways of changing higher education students’ perception of the usefulness of recommended internet web sites for learning purposes, with the intention of increasing the usage rate of recommended module web-sites. The change could represent an adaptation of the existing, well-known technology to change students’ perception regarding its potentially formative role. Subsequently, the outcomes from this preliminary research could be used in order to enhance the quality of the Internet use for teaching and learning purposes

Development status and potential program for development of proliferation-resistant molten-salt reactors

Preliminary studies of existing and conceptual molten-salt reactor (MSR) designs have led to the identification of conceptual systems that are technologically attractive when operated with denatured uranium as the principal fissile fuel. These denatured MSRs would also have favorable resource-utilization characteristics and substantial resistance to proliferation of weapons-usable nuclear materials. The report presents a summary of the current status of technology and a discussion of the major technical areas of a possible base program to develop commercial denatured MSRs. The general areas treated are (1) reactor design and development, (2) safety and safety related technology, (3) fuel-coolant behavior and fuel processing, and (4) reactor materials. A substantial development effort could lead to authorization for construction of a molten-salt test reactor about 5 years after the start of the program and operation of the unit about 10 years later. A prototype commercial denatured MSR could be expected to begin operating 25 years from the start of the program. The postulated base program would extend over 32 years and would cost about $700 million (1978 dollars, unescalated). Additional costs to construct the MSTR,$600 million, and the prototype commercial plant, $1470 million, would bring the total program cost to about$2.8 billion. Additional allowances probably should be made to cover contingencies and incidental technology areas not explicitly treated in this preliminary review