Mechanization of and experience with a triplex fly-by-wire backup control system

A redundant three-axis analog control system was designed and developed to back up a digital fly-by-wire control system for an F-8C airplane. Forty-two flights, involving 58 hours of flight time, were flown by six pilots. The mechanization and operational experience with the backup control system, the problems involved in synchronizing it with the primary system, and the reliability of the system are discussed. The backup control system was dissimilar to the primary system, and it provided satisfactory handling through the flight envelope evaluated. Limited flight tests of a variety of control tasks showed that control was also satisfactory when the backup control system was controlled by a minimum-displacement (force) side stick. The operational reliability of the F-8 digital fly-by-wire control system was satisfactory, with no unintentional downmodes to the backup control system in flight. The ground and flight reliability of the system's components is discussed

Mechanization of and experience with a triplex fly-by-wire backup control system

A redundant three axis analog control system was designed and developed to back up a digital fly by wire control system for an F-8C airplane. The mechanization and operational experience with the backup control system, the problems involved in synchronizing it with the primary system, and the reliability of the system are discussed. The backup control system was dissimilar to the primary system, and it provided satisfactory handling through the flight envelope evaluated. Limited flight tests of a variety of control tasks showed that control was also satisfactory when the backup control system was controlled by a minimum displacement (force) side stick. The operational reliability of the F-8 digital fly by wire control system was satisfactory, with no unintentional downmodes to the backup control system in flight. The ground and flight reliability of the system's components is discussed

Variable-camber systems integration and operational performance of the AFTI/F-111 mission adaptive wing

The advanced fighter technology integration, the AFTI/F-111 aircraft, is a preproduction F-111A testbed research airplane that was fitted with a smooth variable-camber mission adaptive wing. The camber was positioned and controlled by flexing the upper skins through rotary actuators and linkages driven by power drive units. The wing camber and control system are described. The measured servoactuator frequency responses are presented along with analytical predictions derived from the integrated characteristics of the control elements. A mission adaptive wing system chronology is used to illustrate and assess the reliability and dependability of the servoactuator system during 1524 hours of ground tests and 145 hours of flight testing

Flight test of a resident backup software system

A new fault-tolerant system software concept employing the primary digital computers as host for the backup software portion has been implemented and flight tested in the F-8 digital fly-by-wire airplane. The system was implemented in such a way that essentially no transients occurred in transferring from primary to backup software. This was accomplished without a significant increase in the complexity of the backup software. The primary digital system was frame synchronized, which provided several advantages in implementing the resident backup software system. Since the time of the flight tests, two other flight vehicle programs have made a commitment to incorporate resident backup software similar in nature to the system described in this paper

Learning Strong Substitutes Demand via Queries

This paper addresses the computational challenges of learning strong substitutes demand when given access to a demand (or valuation) oracle. Strong substitutes demand generalises the well-studied gross substitutes demand to a multi-unit setting. Recent work by Baldwin and Klemperer shows that any such demand can be expressed in a natural way as a finite list of weighted bid vectors. A simplified version of this bidding language has been used by the Bank of England. Assuming access to a demand oracle, we provide an algorithm that computes the unique list of weighted bid vectors corresponding to a bidder's demand preferences. In the special case where their demand can be expressed using positive bids only, we have an efficient algorithm that learns this list in linear time. We also show super-polynomial lower bounds on the query complexity of computing the list of bids in the general case where bids may be positive and negative. Our algorithms constitute the first systematic approach for bidders to construct a bid list corresponding to non-trivial demand, allowing them to participate in `product-mix' auctions

Diagnostically assessing Western Australian Year 11 students\u27 engagement with theory in Visual Arts

Theory linked to visual arts’ responding outcomes, is fundamental to the visual arts curriculum in facilitating visual literacy, or students’ ability to assemble meaning from, and construct new imagery. Without visual literacy, year 11 students are limited in understanding and fully participating in our technological, image-based society. Subsequently, a mixed methods doctoral study was undertaken to investigate students’ engagement in visual arts theory tasks, as increased engagement in theory was anticipated to improve students’ visual literacy outcomes. A diagnostic instrument was created to measure year 11 students’ prior learning in visual arts theory, as well as their cognitive and psychological engagement. Interviews with year 11 students, visual arts teachers, and some principals or representatives, supported the development of the instrument and contextualised the findings. Whilst the research is ongoing, findings suggest measuring students’ engagement facilitates the diagnosis of key issues and knowledge gaps affecting students’ learning. Initial findings also confirm limited psychological engagement acts as a barrier to learning in visual arts’ theory

Cross-cultural and experiential learning in El Salvador for extension specialists : lessons learned in the field

A delegation from Lincoln University (LU) Cooperative Extension of Missouri participated in a 12-day exchange program that included visits to communities and institutions in Central and Western El Salvador. The delegation included LU Native Plants Program (LU-NPP) staff and members of four communities in Missouri. The objectives were: 1. For the LU delegation to be immersed in the Salvadoran culture and learn how communities protect their resources and use native plants in their daily lives; 2. To exchange lessons learned between the LU-NPP, Salvadoran educators, producers, farmers, and communities; and 3. Identify organizations or agencies interested in forming alliances with the LU-NPP. Joint collaborative efforts between LU and organizations in El Salvador will help empower small farmers and will further advance agricultural and ecological education for low-income students in El Salvador and in Missouri. During site visits, local leaders from different agencies and community organizations and the LU delegation engaged in conversations to learn from each other's experiences. Salvadoran specialists were surprised to learn that Lincoln University also works with low-income communities and that farms in Missouri do not only grow cash crops. Many of the Native Plant Program's lessons learned in Missouri could be adopted in El Salvador to help small farmers and rural entrepreneurs. Evaluations from participants of this exchange program indicate that the delegation members increased their level of understanding of Latino culture and some had the opportunity to practice their Spanish skills which they can also use in Missouri. This program was funded by the USDA National Institute of Food and Agriculture (NIFA) and was part of two Capacity Building Grants

Solving Strong-Substitutes Product-Mix Auctions

This paper develops algorithms to solve strong-substitutes product-mix auctions. That is, it finds competitive equilibrium prices and quantities for agents who use this auction's bidding language to truthfully express their strong-substitutes preferences over an arbitrary number of goods, each of which is available in multiple discrete units. (Strong substitutes preferences are also known, in other literatures, as $M^\natural$-concave, matroidal and well-layered maps, and valuated matroids). Our use of the bidding language, and the information it provides, contrasts with existing algorithms that rely on access to a valuation or demand oracle to find equilibrium. We compute market-clearing prices using algorithms that apply existing submodular minimisation methods. Allocating the supply among the bidders at these prices then requires solving a novel constrained matching problem. Our algorithm iteratively simplifies the allocation problem, perturbing bids and prices in a way that resolves tie-breaking choices created by bids that can be accepted on more than one good. We provide practical running time bounds on both price-finding and allocation, and illustrate experimentally that our allocation mechanism is practical