Digital electronic engine control history

Full authority digital electronic engine controls (DEECs) were studied, developed, and ground tested because of projected benefits in operability, improved performance, reduced maintenance, improved reliability, and lower life cycle costs. The issues of operability and improved performance, however, are assessed in a flight test program. The DEEC on a F100 engine in an F-15 aircraft was demonstrated and evaluated. The events leading to the flight test program are chronicled and important management and technical results are identified

X-29 flight-research program

The X-29A aircraft is the first manned, experimental high-performance aircraft to be fabricated and flown in many years. The approach for expanding the X-29 flight envelope and collecting research data is described including the methods for monitoring wind divergence, flutter, and aeroservoelastic coupling of the aerodynamic forces with the structure and the flight-control system. Examples of the type of flight data to be acquired are presented along with types of aircraft maneuvers that will be flown. A brief description of the program management structure is also presented and the program schedule is discussed

Equations for the determination of humidity from dewpoint and psychrometric data

A general expression based on the Claperon-Clausius differential equation that relates saturation vapor pressure, absolute temperature, and the latent heat of transformation was derived that expresses saturation vapor pressure as a function of absolute temperature. This expression was then used to derive general expressions for vapor pressure, absolute humidity, and relative humidity as functions of either dewpoint and ambient temperature or psychrometric parameters. Constants for all general expressions were then evaluated to give specific expressions in both the international system of units and U.S. customary units for temperatures above and below freezing

Measurements of sonic booms generated by an airplane flying at Mach 3.5 and 4.8

Sonic booms generated by the X-15 airplane flying at Mach numbers of 3.5 and 4.8 were measured. The experimental results agreed within 12 percent with results obtained from theoretical methods. No unusual phenomena related to overpressure were encountered. Scaled data from the X-15 airplane for Mach 4.8 agreed with data for an SR-71 airplane operating at lower Mach numbers and similar altitudes. The simple technique used to scale the data on the basis of airplane lift was satisfactory for comparing X-15 and SR-71 sonic boom signatures

Closing the design loop on HiMAT (highly maneuverable aircraft technology)

The design methodology used in the HiMAT program and the wind tunnel development activities are discussed. Selected results from the flight test program are presented and the strengths and weaknesses of testing advanced technology vehicles using the RPV concept is examined. The role of simulation on the development of digital flight control systems and in RPV's in particular is emphasized

Montrul, Silvina: The acquisition of heritage languages

The last two decades have witnessed a dramatic increase in the interest in heritage language acquisition, maintenance, and attrition by both scholar and layman alike. The formal study of heritage languages and the status of their grammars have in many ways served as an important missing, complementary subfield of inquiry in our quest to better understand bi- and multilingual grammars in the mind and society. To date, what this nascent field has been sorely lacking is a volume – or a canonical set of works – that functions as a solid reference upon which future research can be built. In this work Silvina Montrul takes on the unenviable task of presenting this type of reference work for both specialist and neophyte to this ever-growing field of study. In my estimation, this book is an invaluable resource for a wide audience, although it is probably most useful for scholars new to the field

John J. McCarthy and Joe Pater (eds.): Harmonic grammar and harmonic serialism.

This volume contains chapters that explore and extend advances in formal investigations of grammar that employ violable constraints in the analysis of individual languages, the study of linguistic typology, and the learnability of grammars. Initial investigations in a generative framework that employs violable constraints took place in Optimality Theory (OT) (Prince & Smolensky, 1993/2004). It is worth noting that although “representational constraints had of course long existed as a means of formally expressing restrictions on linguistic structures, […] the notion that one constraint could compel the violation of another had never been given much attention before OT” (p. vii). The violable constraints in OT are strictly ranked with respect to one another, preventing the possibility of multiple violations of lower-ranked constraints accumulating and ‘ganging up’ on higher ranked ones. Harmonic Grammar (HG) is an alternative version of a grammar model that employs violable, ranked constraints (as is commonplace in OT) which uses weighted constraints in place of strictly ranked ones. Pater (this volume) highlights two potential advantages that an HG may have over an OT-model: Firstly, as initially noted by Prince (2003), there are asymmetric trade-offs on gang effects (based on the fact that the weighted constraint violations in HG can lead to gang effects of lower weighted constraints under certain circumstances), which are simply not possible in OT. Secondly, “the promise of weighted constraint theories of Universal Grammar derives from the ability of HG to generate attested patterns that fall out of the reach of OT using the same sets of constraints” (p. 2). Here Pater points to previous research (in particular, Flemming, 2001) that shows the difficulty that OT has in establishing compatibility with scalar constraints. This potential issue purportedly receives a more straightforward account in HG. The inclusion of weighted constraints permits new theories concerning which constraints (Con) exist. Initially, analyses in OT assumed a parallel theory of candidate generation and evaluation. There is no reason, however, that single iterative applications of the generation (Gen) and evaluation (Eval) of candidates cannot replace parallel evaluations. Harmonic Serialism (HS), see McCarthy (this volume) for a detailed introduction, combines the inclusion of weighted violable constraints in serial evaluation of candidates. The contributions in this volume consist of studies that show the advantages and challenges associated with current research within the HG and HS models

Progovac, Liliana: Evolutionary syntax.

In this monograph, Liliana Progovac (LP) challenges this mainstream assumption in presenting her case for a gradualist, adaptationist approach to the evolution of syntax