5,384 research outputs found

    Recent payment trends in the United States

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    Payment systems

    Creating a Portable MP3 Player Three-Band Graphic Equalizer and Amplifier for a Circuits Laboratory Final Project

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    At George Fox University, all engineering students are required to take the sophomore level circuits course. In an effort to more effectively engage the students in the course, a new final project was designed to leverage the interest in music and audio that is shared by undergraduate students. This paper details the design and implementation of a battery powered, three-band graphic equalizer and amplifier for a portable MP3 player or IPOD® and the associated labs and project that accompany it. There are three circuit design elements of the final project, the first teaching students how to use comparators to create a graphic display, the second detailing active filters, and the final lab describing peak rectifiers and the mixer that ties everything together. As a final project experience, each student is given a kit containing a PCB, a speaker, an on/off switch, a batteryholder, and every electronic component required to construct the final system. Students are also required to write a major lab report detailing the operation of the final project. After providing the experience one time, student engagement was noticeably higher, the results of the final project being significantly beyond the expectations of the course instructors

    The check is dead! Long live the check! A Check 21 update

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    Check 21 legislation has enabled the check clearing system to transform from paper to electronics, and much more rapidly than some had predicted. As a result of competition with other payment methods, check use has been declining since the mid-1990s, but because of the rapid adoption of electronic payment methods, checks are evolving and are unlikely to disappear anytime soon. Checks are still a convenient way to initiate some payments, and electronic processing has only made them more competitive with all types of electronic payments.Checks ; Electronic funds transfers

    Factors affecting handling qualities of a lift-fan aircraft during steep terminal area approaches

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    The XV-5B lift-fan aircraft was used to explore the factors affecting handling qualities in the terminal area. A 10 deg ILS approach task was selected to explore these problems. Interception of the glide slope at 457.2 m, glide slope tracking, deceleration along the glide slope to a spot hover were considered. Variations in airplane deck angle, deceleration schedule, and powered-lift management were studied. The overall descent performance envelope was identified on the basis of fan stall, maximum comfortable descent rate, and controllability restrictions. The collective-lift stick provided precise glide slope tracking capability. The pilot preferred a deck-parallel attitude for which he used powered lift to control glide slope and pitch attitude to keep the angle of attack near zero. Workload was reduced when the deceleration schedule was delayed until the aircraft was well established on the glide slope, since thrust vector changes induced flight path disturbances

    The effects of pilot stress factors on handling quality assessments during US/German helicopter agility flight tests

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    Flight tests were conducted with two helicopters to study and evaluate the effects of helicopter characteristics and pilot and task demands on performance in nap-of-the-Earth flight. Different, low-level slalom courses were set up and were flown by three pilots with different levels of flight experience. A pilot rating questionnaire was used to obtain redundant information and to gain more insight into factors that influence pilot ratings. The flight test setups and procedures are described, and the pilot ratings are summarized and interpreted in close connection with the analyzed test data. Pilot stress is discussed. The influence of demands on the pilot, of the helicopter characteristics, and of other stress factors are outlined with particular emphasis on how these factors affect handling-qualities assessment

    A Sequential Two-Step Algorithm for Fast Generation of Vehicle Racing Trajectories

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    The problem of maneuvering a vehicle through a race course in minimum time requires computation of both longitudinal (brake and throttle) and lateral (steering wheel) control inputs. Unfortunately, solving the resulting nonlinear optimal control problem is typically computationally expensive and infeasible for real-time trajectory planning. This paper presents an iterative algorithm that divides the path generation task into two sequential subproblems that are significantly easier to solve. Given an initial path through the race track, the algorithm runs a forward-backward integration scheme to determine the minimum-time longitudinal speed profile, subject to tire friction constraints. With this fixed speed profile, the algorithm updates the vehicle's path by solving a convex optimization problem that minimizes the resulting path curvature while staying within track boundaries and obeying affine, time-varying vehicle dynamics constraints. This two-step process is repeated iteratively until the predicted lap time no longer improves. While providing no guarantees of convergence or a globally optimal solution, the approach performs very well when validated on the Thunderhill Raceway course in Willows, CA. The predicted lap time converges after four to five iterations, with each iteration over the full 4.5 km race course requiring only thirty seconds of computation time on a laptop computer. The resulting trajectory is experimentally driven at the race circuit with an autonomous Audi TTS test vehicle, and the resulting lap time and racing line is comparable to both a nonlinear gradient descent solution and a trajectory recorded from a professional racecar driver. The experimental results indicate that the proposed method is a viable option for online trajectory planning in the near future

    A piloted simulator investigation of stability and control, display and crew-loading requirements for helicopter instrument approach. Part 2: Supporting data

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    Pilot rating comments and standard deviation measures of flight performance and control use are presented

    A ground-simulator investigation of helicopter longitudinal flying qualities for instrument approach

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    A ground-simulation experiment was conducted to investigate the direct and interactive influences of several longitudinal static and dynamic stability parameters on helicopter flying qualities during terminal-area operations in instrument conditions. Variations that were examined included five levels of static control-position gradients ranging from stable to unstable; two levels of dynamic stability for the long-period oscillation; two levels of the steady-state pitch speed gradient; two levels of angle-of-attack stability and pitch-rate damping; and two levels of stability and control augmentation. These variations were examined initially in calm air and thin in simulated light-to-moderate turbulence and wind shear. Five pilots performed a total of 223 evaluations of these parameters for a representative microwave landing system precision approach task conducted in a dual-pilot crew-loading situation

    A piloted simulator investigation of stability and control, display and crew-loading requirements for helicopter instrument approach. Part 1: Technical discussion and results

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    A ground-simulation experiment was conducted to investigate the influence and interaction of flight-control system, fight-director display, and crew-loading situation on helicopter flying qualities during terminal area operations in instrument conditions. The experiment was conducted on the Flight Simulator for Advanced Aircraft at Ames Research Center. Six levels of control complexity, ranging from angular rate damping to velocity augmented longitudinal and vertical axes, were implemented on a representative helicopter model. The six levels of augmentation were examined with display variations consisting of raw elevation and azimuth data only, and of raw data plus one-, two-, and three-cue flight directors. Crew-loading situations simulated for the control-display combinations were dual-pilot operation (representative auxiliary tasks of navigation, communications, and decision-making). Four pilots performed a total of 150 evaluations of combinations of these parameters for a representative microwave landing system (MLS) approach task
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