Platinum(II), palladium(II), nickel(II), and gold(I) complexes of the “electrospray-friendly” thiolate ligands 4-SC₅H₄N- and 4-SC₆H₄OMe-

The series of platinum(II), palladium(II), and nickel(II) complexes [ML₂(dppe)] [M = Ni, Pd, Pt; L = 4-SC₅H₄N or 4-SC₆H₄OMe; dppe = Ph₂PCH₂CH₂PPh₂] containing pyridine-4-thiolate or 4-methoxybenzenethiolate ligands, together with the corresponding gold(I) complexes [AuL(PPh3)], were prepared and their electrospray ionization mass spectrometric behavior compared with that of the thiophenolate complexes [M(SPh)₂(dppe)] (M = Ni, Pd, Pt) and [Au(SPh)(PPh₃)]. While the pyridine-4-thiolate complexes yielded protonated ions of the type [M + H]+ and [M + 2H]²+ ions in the Ni, Pd, and Pt complexes, an [M + H]+ ion was only observed for the platinum derivative of 4-methoxybenzenethiolate. Other ions, which dominated the spectra of the thiophenolate complexes, were formed by thiolate loss and aggregate formation. The X-ray crystal structure of [Pt(SC₆H₄OMe-4)₂(dppe)] is also reported

Piloting considerations for terminal area operations of civil tiltwing and tiltrotor aircraft

The existing body of research to investigate airworthiness, performance, handling, and operational requirements for STOL and V/STOL aircraft was reviewed for its applicability to the tiltrotor and tiltwing design concepts. The objective of this study was to help determine the needs for developing civil certification criteria for these aircraft concepts. Piloting tasks that were considered included configuration and thrust vector management, glidepath control, deceleration to hover, and engine failure procedures. Flight control and cockpit display systems that have been found necessary to exploit the low-speed operating characteristics of these aircraft are described, and beneficial future developments are proposed

Flight Dynamics Aspects of a Large Civil Tiltrotor Simulation Using Translational Rate Command

An in-depth analysis of a Large Civil Tiltrotor simulation with a Translational Rate Command control law that uses automatic nacelle deflections for longitudinal velocity control and lateral cyclic for lateral velocity control is presented. Results from piloted real-time simulation experiments and offline time and frequency domain analyses are used to investigate the fundamental flight dynamic and control mechanisms of the control law. The baseline Translational Rate Command conferred handling qualities improvements over an attitude command attitude hold control law but in some scenarios there was a tendency to enter PIO. Nacelle actuator rate limiting strongly influenced the PIO tendency and reducing the rate limits degraded the handling qualities further. Counterintuitively, increasing rate limits also led to a worsening of the handling qualities ratings. This led to the identification of a nacelle rate to rotor longitudinal flapping coupling effect that induced undesired pitching motions proportional to the allowable amount of nacelle rate. A modification that applied a counteracting amount of longitudinal cyclic proportional to the nacelle rate significantly improved the handling qualities. The lateral axis of the Translational Rate Command conferred Level 1 handling qualities in a Lateral Reposition maneuver. Analysis of the influence of the modeling fidelity on the lateral flapping angles is presented. It is showed that the linear modeling approximation is likely to have under-predicted the side-force and therefore under-predicted the lateral flapping at velocities above 15 ft/s. However, at lower velocities, and therefore more weakly influenced by the side force modeling, the accelerations that the control law commands also significantly influenced the peak levels of lateral flapping achieved

Toward an Understanding of Beaver Management as Human and Beaver Densities Increase

Estimates of beaver (Castor canadensis) density play an important role in wildlife managers’ decisions about beaver population management, because managers anticipate higher incidence of problem complaints when a beaver population increases. To manage the impacts of beavers in an urbanizing landscape, managers need better information on changes in stakeholder beliefs and attitudes as beaver and human densities reach high levels. We conducted additional analysis of data collected in 2002 through mail surveys of residents in New York and Massachusetts to test hypothesized relationships between beaver density and damage experience, attitudes toward beavers, and norms about beaver management actions. Consistent with previous research, we found a correlation between personal experience with beaver-related problems, lower acceptance capacity for beavers, and higher acceptability of lethal beaver management actions. In comparison to residents living in areas with low beaver density, residents of areas with high beaver density were more likely to: experience beaver-related problems; believe that beaver-related damage had greatly increased in their area; express a preference for beaver population reduction; express less tolerant attitudes toward beaver presence; and accept lethal control of beavers as a response to beaver-related problems. These findings add to understanding of wildlife acceptance capacity, generally, and tolerance of beavers specifically. Based on our findings, we propose a conceptual model representing key dynamic interrelationships between stakeholder attitudes, norms, and common beaver management practices. We discuss a causal loop diagram representing the model to illuminate the challenges wildlife managers are likely to face as the context for beaver management changes. The model articulates the dynamic complexity of urban beaver management and fills a gap in the literature by conceptualizing beaver management as a coupled human–natural system. Such models may aid communication in locales where high densities of beaver and people set the stage for human–wildlife conflict and emergence of disruptive wildlife management issues

How do Suburban Coyote Attacks Affect Residents’ Perceptions? Insights from a New York Case Study

Understanding the human dimensions of human-coyote conflicts in metropolitan areas has taken on greater importance as coyotes (Canis latrans) have established themselves as the top predator in many urban ecosystems across North America. Though uncommon, coyote attacks on humans do occur in metropolitan areas and often receive widespread media coverage. Little research has been done to clarify how media coverage of these uncommon events may influence urban residents’ attitudes toward coyotes. In 2010, two children in Westchester County, New York, were injured in coyote attacks. In fall 2010 and winter 2011, the authors replicated a 2006 telephone survey in two areas of Westchester County, to assess possible changes in residents’ coyote-related experiences, attitudes, and risk perceptions. We documented a substantial, short-term increase in local newspaper coverage about coyotes immediately after the attack. Over 90% of local residents were aware of July 2010 attacks and nearly all residents with awareness reported exposure to media coverage of the attacks (supporting the hypothesis that such media coverage can have an agenda-setting effect). In comparison to 2006 levels, we documented an increase in concern about problems coyotes may cause, concern about coyote-related safety threats to children, and a decline in the proportion of local residents who believed that coyote-related risk to children was acceptably low. The 2006-2010 data comparisons provide support for a media framing hypothesis (i.e., that exposure to media coverage about the attacks made thoughts of human safety more salient, contributing to at least a short-term influence on concern about coyotes). Yet, in early 2011, months after local media coverage of coyotes had returned to background levels, concern about coyotes and coyote-related threats to children remained significantly higher than 2006 levels (i.e., effects continued after media priming ceased). This result suggests that factors other than media priming are needed to explain elevated levels of concern. We hypothesize that awareness of a new impact associated with coyotes (i.e., safety risk to children) may have driven change in resident’s perceptions of coyote-related risk and tolerance for coyote presence. Findings suggest that interventionists with interests in promoting wildlife conservation in urban ecosystems have a window of opportunity in which coyote-related messages may be attended to by local residents. Through efforts to enhance self-efficacy and teach residents how they can reduce the likelihood of a negative interaction with coyotes, interventionists can help human residents learn to live with this mesopredator in urban ecosystems

Sports Holdings in the Southeastern Conference University Libraries: Football as a Case Study

Of the twelve National Collegiate Athletic Association’s (NCAA) Division I Football Bowl Subdivision conferences, the Southeastern Conference (SEC) has attained prominence. But how do the SEC’s university libraries fare when evaluated for their football holdings? While university libraries develop their collections mainly to support research and teaching functions, according to accepted collection development practice, the extent to which sports of local importance are represented in their collections is a subject given little attention in the professional literature. In order to help close the gap, this study evaluates the football holdings of the 12 SEC university library systems using the checklist method of each library’s Online Public Access Catalog (OPAC) system from a remote location. The evaluation is meant to serve as a case study of sports holdings in the SEC libraries by using an authoritative checklist consisting of the best fiction and nonfiction football books. The checklist method, which compares a library’s holdings to an authoritative list, is an effective means of identifying collection strengths and weaknesses

An Investigation of Large Tilt-Rotor Hover and Low Speed Handling Qualities

A piloted simulation experiment conducted on the NASA-Ames Vertical Motion Simulator evaluated the hover and low speed handling qualities of a large tilt-rotor concept, with particular emphasis on longitudinal and lateral position control. Ten experimental test pilots evaluated different combinations of Attitude Command-Attitude Hold (ACAH) and Translational Rate Command (TRC) response types, nacelle conversion actuator authority limits and inceptor choices. Pilots performed evaluations in revised versions of the ADS-33 Hover, Lateral Reposition and Depart/Abort MTEs and moderate turbulence conditions. Level 2 handling qualities ratings were primarily recorded using ACAH response type in all three of the evaluation maneuvers. The baseline TRC conferred Level 1 handling qualities in the Hover MTE, but there was a tendency to enter into a PIO associated with nacelle actuator rate limiting when employing large, aggressive control inputs. Interestingly, increasing rate limits also led to a reduction in the handling qualities ratings. This led to the identification of a nacelle rate to rotor longitudinal flapping coupling effect that induced undesired, pitching motions proportional to the allowable amount of nacelle rate. A modification that counteracted this effect significantly improved the handling qualities. Evaluation of the different response type variants showed that inclusion of TRC response could provide Level 1 handling qualities in the Lateral Reposition maneuver by reducing coupled pitch and heave off axis responses that otherwise manifest with ACAH. Finally, evaluations in the Depart/Abort maneuver showed that uncertainty about commanded nacelle position and ensuing aircraft response, when manually controlling the nacelle, demanded high levels of attention from the pilot. Additional requirements to maintain pitch attitude within 5 deg compounded the necessary workload

Evaluation of two cockpit display concepts for civil tiltrotor instrument operations on steep approaches

A piloted simulation experiment was conducted using the NASA Ames Research Center Vertical Motion Simulator to evaluate two cockpit display formats designed for manual control on steep instrument approaches for a civil transport tiltrotor aircraft. The first display included a four-cue (pitch, roll, power lever position, and nacelle angle movement prompt) flight director. The second display format provided instantaneous flight path angle information together with other symbols for terminal area guidance. Pilots evaluated these display formats for an instrument approach task which required a level flight conversion from airplane-mode flight to helicopter-mode flight while decelerating to the nominal approach airspeed. Pilots tracked glide slopes of 6, 9, 15 and 25 degrees, terminating in a hover for a vertical landing on a 150 feet square vertipad. Approaches were conducted with low visibility and ceilings and with crosswinds and turbulence, with all aircraft systems functioning normally and were carried through to a landing. Desired approach and tracking performance was achieved with generally satisfactory handling qualities using either display format on glide slopes up through 15 degrees. Evaluations with both display formats for a 25 degree glide slope revealed serious problems with glide slope tracking at low airspeeds in crosswinds and the loss of the intended landing spot from the cockpit field of view

An Investigation of Large Tilt-Rotor Short-Term Attitude Response Handling Qualities Requirements in Hover

A piloted simulation investigation was conducted using the NASA Ames Vertical Motion Simulator to study the impact of pitch, roll and yaw attitude bandwidth and phase delay on handling qualities of large tilt-rotor aircraft. Multiple bandwidth and phase delay pairs were investigated for each axis. The simulation also investigated the effect that the pilot offset from the center of gravity has on handling qualities. While pilot offset does not change the dynamics of the vehicle, it does affect the proprioceptive and visual cues and it can have an impact on handling qualities. The experiment concentrated on two primary evaluation tasks: a precision hover task and a simple hover pedal turn. Six pilots flew over 1400 data runs with evaluation comments and objective performance data recorded. The paper will describe the experiment design and methodology, discuss the results of the experiment and summarize the findings

An Investigation of Rotorcraft Stability-Phase Margin Requirements in Hover

A cooperative study was performed to investigate the handling quality effects from reduced flight control system stability margins, and the trade-offs with higher disturbance rejection bandwidth (DRB). The piloted simulation study, perform on the NASA-Ames Vertical Motion Simulator, included three classes of rotorcraft in four configurations: a utility-class helicopter; a medium-lift helicopter evaluated with and without an external slung load; and a large (heavy-lift) civil tiltrotor aircraft. This large aircraft also allowed an initial assessment of ADS-33 handling quality requirements for an aircraft of this size. Ten experimental test pilots representing the U.S. Army, Marine Corps, NASA, rotorcraft industry, and the German Aerospace Center (DLR), evaluated the four aircraft configurations, for a range of flight control stability-margins and turbulence levels, while primarily performing the ADS-33 Hover and Lateral Reposition MTEs. Pilot comments and aircraft-task performance data were analyzed. The preliminary stability margin results suggest higher DRB and less phase margin cases are preferred as the aircraft increases in size. Extra care will need to be taken to assess the influence of variability when nominal flight control gains start with reduced margins. Phase margins as low as 20-23 degrees resulted in low disturbance-response damping ratios, objectionable oscillations, PIO tendencies, and a perception of an incipient handling qualities cliff. Pilot comments on the disturbance response of the aircraft correlated well to the DRB guidelines provided in the ADS-33 Test Guide. The A D-3S3 mid-term response-to-control damping ratio metrics can be measured and applied to the disturbance-response damping ratio. An initial assessment of LCTR yaw bandwidth shows the current Level 1 boundary needs to be relaxed to help account for a large pilot off-set from the c.g. Future efforts should continue to investigate the applicability/refinement of the current ADS-33 requirements to large vehicles, like an LCTR