An Investigation of the Ability to Recover from Transients Following Failures for Single-Pilot Rotorcraft

A moving-base simulation was conducted to investigate a pilot's ability to recover from transients following single-axis hard-over failures of the flight-control system. The investigation was performed in conjunction with a host simulation that examined the influence of control modes on a single pilot's ability to perform various mission elements under high-workload conditions. The NASA Ames large-amplitude-motion Vertical Motion Simulator (VMS) was utilized, and the experimental variables were the failure axis, the severity of the failure, and the airspeed at which the failure occurred. Other factors, such as pilot workload and terrain and obstacle proximity at the time of failure, were kept as constant as possible within the framework of the host simulation task scenarios. No explicit failure warnings were presented to the pilot. Data from the experiment are shown, and pilot ratings are compared with the proposed handling-qualities requirements for military rotorcraft. Results indicate that the current proposed failure transient requirements may need revision

The Fed's entry into check clearing reconsidered

Check collection systems ; Federal Reserve System

An analysis of ultraviolet spectra of Extreme Helium Stars and new clues to their origins

Abundances of about 18 elements including the heavy elements Y and Zr are determined from Hubble Space Telescope Space Telescope Imaging Spectrograph ultraviolet spectra of seven extreme helium stars (EHes): LSE 78, BD+10 2179, V1920 Cyg, HD 124448, PV Tel, LS IV -1 2, and FQ Aqr. New optical spectra of the three stars -- BD+10 2179, V1920 Cyg, and HD 124448 were analysed. The abundance analyses is done using LTE line formation and LTE model atmospheres especially constructed for these EHe stars. The stellar parameters derived from an EHe's UV spectrum are in satisfactory agreement with those derived from its optical spectrum. Adopted abundances for the seven EHes are from a combination of the UV and optical analyses. Published results for an additional ten EHes provide abundances obtained in a nearly uniform manner for a total of 17 EHes, the largest sample on record. The initial metallicity of an EHe is indicated by the abundance of elements from Al to Ni; Fe is adopted to be the representative of initial metallicity. Iron abundances range from approximately solar to about one-hundredth of solar. Clues to EHe evolution are contained within the H, He, C, N, O, Y, and Zr abundances. Two novel results are (i) the O abundance for some stars is close to the predicted initial abundance yet the N abundance indicates almost complete conversion of initial C, N, and O to N by the CNO-cycles; (ii) three of the seven stars with UV spectra show a strong enhancement of Y and Zr attributable to an s-process. The observed compositions are discussed in light of expectations from accretion of a He white dwarf by a CO white dwarf.Comment: 126 pages, 15 figures, 20 Tables, accepted for publication in the Ap

Tunable Integrated-Optics Nanoscaled Devices Based on Magnetic Photonic Crystals

Magnetooptical properties of magnetic photonic crystals have been investigated in the view of their possible applications for the modern integrated-optics devices. A "transfer matrices" formalism was expanded for the case of oblique light incidence on the periodic nanoscaled magnetic multilayered systems. Several new effects such as the Faraday effect dependence on the incidence angle and the tunability of the bandgap defect modes spectral location by external magnetic fields were found. Several possibilities of one-dimensional magnetic photonic crystals applications for the optical devices are discussed. Initial steps towards the practical implementation of the proposed devices are reported.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Lunar mining of oxygen using fluorine

Experiments during the first year of the project were directed towards generating elemental fluorine via the electrolysis of anhydrous molten fluorides. Na2SiF6 was dissolved in either molten NaBF4 or a eutectic (minimum-melting) mixture of KF-LiF-NaF and electrolyzed between 450 and 600 C to Si metal at the cathode and F2 gas at the anode. Ar gas was continuously passed through the system and F2 was trapped in a KBr furnace. Various anode and cathode materials were investigated. Despite many experimental difficulties, the capability of the process to produce elemental fluorine was demonstrated

Don't break a leg: Running birds from quail to ostrich prioritise leg safety and economy in uneven terrain

Cursorial ground birds are paragons of bipedal running that span a 500-fold mass range from quail to ostrich. Here we investigate the task-level control priorities of cursorial birds by analysing how they negotiate single-step obstacles that create a conflict between body stability (attenuating deviations in body motion) and consistent leg force–length dynamics (for economy and leg safety). We also test the hypothesis that control priorities shift between body stability and leg safety with increasing body size, reflecting use of active control to overcome size-related challenges. Weight-support demands lead to a shift towards straighter legs and stiffer steady gait with increasing body size, but it remains unknown whether non-steady locomotor priorities diverge with size. We found that all measured species used a consistent obstacle negotiation strategy, involving unsteady body dynamics to minimise fluctuations in leg posture and loading across multiple steps, not directly prioritising body stability. Peak leg forces remained remarkably consistent across obstacle terrain, within 0.35 body weights of level running for obstacle heights from 0.1 to 0.5 times leg length. All species used similar stance leg actuation patterns, involving asymmetric force–length trajectories and posture-dependent actuation to add or remove energy depending on landing conditions. We present a simple stance leg model that explains key features of avian bipedal locomotion, and suggests economy as a key priority on both level and uneven terrain. We suggest that running ground birds target the closely coupled priorities of economy and leg safety as the direct imperatives of control, with adequate stability achieved through appropriately tuned intrinsic dynamics

Apparatus and method for high-speed characterization of surfaces

This invention permits rapid determination of a three-dimensional contour of an object. The apparatus directs a laser beam onto a point on an object, and the scattered light is received by a position sensitive detector (PSD). The location at which scattered light is received can be related to the displacement of the point on the object, using basic trigonometry. The laser beam is deflected non-mechanically, by passing it through a crystal whose index of refraction is varied in a controlled manner. By proper control of the index of refraction, one can scan the beam across a desired area of the object, without using any moving parts, and can therefore obtain complete information about the contour of the object. The device operates without making any conventional images, and is therefore much faster than comparable devices of the prior art. Also, the laser and beam deflector can be housed in a small optical head which enables the device to reach normally inaccessible areas. The device can compare the test object with a reference object, or it can compare two objects for differences

Space station thermal control surfaces

Mission planning documents were used to analyze the radiator design and thermal control surface requirements for both space station and 25-kW power module, to analyze the missions, and to determine the thermal control technology needed to satisfy both sets of requirements. Parameters such as thermal control coating degradation, vehicle attitude, self eclipsing, variation in solar constant, albedo, and Earth emission are considered. Four computer programs were developed which provide a preliminary design and evaluation tool for active radiator systems in LEO and GEO. Two programs were developed as general programs for space station analysis. Both types of programs find the radiator-flow solution and evaluate external heat loads in the same way. Fortran listings are included

The Ogoni of Nigeria

The Ogoni are a minority ethnic people who live in the Western Niger Delta Region of southern Nigeria. During the 1970s, Ogoniland, or the Ogoni Nation, became part of the Rivers State of Nigeria. There are approximately 500,000 Ogoni who represent less than 0.05 percent of Nigeria\u27s 100 to 120 million people. The population density of this region equals 1,233 people per square mile, making it one of the most densely populated areas of Nigeria. Reliable information about the origin of the Ogoni is limited. Archaeological and oral historical evidence suggests that the Ogoni have inhabited the area for over 500 years. Presently, two theories exist about the origin of this people. First, the Ogoni may have migrated into their present territory from across the Imo River sometime around the eighteenth or the nineteenth century. Vestiges of this migration are two Ogoni villages, Warife and Utetuk, that still exist at the other side of the river. Warife still speak Khana, whereas Utetuk have adopted the customs and language of Annang, a neighboring tribe in the Akwa Ibom State. When they arrived in the region, the Ogoni did not find this area to be occupied. As a consequence, they were able to keep their identity from their neighbors-the Ibibios in the southeast, the Igbos to the north, the Ikwerres to the west, and the Andoni and Ijaws to the south. According to this theory, the first Ogoni settlement was in the Khana kingdom, followed by Tai, Gokana, and Eleme, respectively. The Ogoni Nation grew from these first settlements. The second theory claims that the Ogoni people came on the trading ships, which often visited Bonny, a small city-state island in the delta. They began to settle in Bonny until their population began to outgrow the little town. This necessitated their migration further inland. Once they arrived at Bonny, the resident Ibani people referred to the new arrivals as the Igoni or strangers. As time passed, the Ibani then became known as the Ogoni. Today, in Bonny, people say that the Ogoni and the Ibani are brothers. It is quite possible that Ogoni residence on this island in the delta prevented them from being captured during the slave raids that ravaged the mainland

The Ogoni of Nigeria

The Ogoni are a minority ethnic people who live in the Western Niger Delta Region of southern Nigeria. During the 1970s, Ogoniland, or the Ogoni Nation, became part of the Rivers State of Nigeria. There are approximately 500,000 Ogoni who represent less than 0.05 percent of Nigeria\u27s 100 to 120 million people. The population density of this region equals 1,233 people per square mile, making it one of the most densely populated areas of Nigeria. Reliable information about the origin of the Ogoni is limited. Archaeological and oral historical evidence suggests that the Ogoni have inhabited the area for over 500 years. Presently, two theories exist about the origin of this people. First, the Ogoni may have migrated into their present territory from across the Imo River sometime around the eighteenth or the nineteenth century. Vestiges of this migration are two Ogoni villages, Warife and Utetuk, that still exist at the other side of the river. Warife still speak Khana, whereas Utetuk have adopted the customs and language of Annang, a neighboring tribe in the Akwa Ibom State. When they arrived in the region, the Ogoni did not find this area to be occupied. As a consequence, they were able to keep their identity from their neighbors-the Ibibios in the southeast, the Igbos to the north, the Ikwerres to the west, and the Andoni and Ijaws to the south. According to this theory, the first Ogoni settlement was in the Khana kingdom, followed by Tai, Gokana, and Eleme, respectively. The Ogoni Nation grew from these first settlements. The second theory claims that the Ogoni people came on the trading ships, which often visited Bonny, a small city-state island in the delta. They began to settle in Bonny until their population began to outgrow the little town. This necessitated their migration further inland. Once they arrived at Bonny, the resident Ibani people referred to the new arrivals as the Igoni or strangers. As time passed, the Ibani then became known as the Ogoni. Today, in Bonny, people say that the Ogoni and the Ibani are brothers. It is quite possible that Ogoni residence on this island in the delta prevented them from being captured during the slave raids that ravaged the mainland