How complicated must an optical component be?

We analyze how complicated a linear optical component has to be if it is to perform one of a range of functions. Specifically, we devise an approach to evaluating the number of real parameters that must be specified in the device design or fabrication, based on the singular value decomposition of the linear operator that describes the device. This approach can be used for essentially any linear device, including space-, frequency-, or time-dependent systems, in optics or in other linear wave problems. We analyze examples including spatial mode converters and various classes of wavelength demultiplexers. We consider limits on the functions that can be performed by simple optical devices such as thin lenses, mirrors, gratings, modulators, and fixed optical filters, and discuss the potential for greater functionalities using modern nanophotonics

Fundamental Limit to Linear One-Dimensional Slow Light Structures

Using a new general approach to limits in optical structures that counts orthogonal waves generated by scattering, we derive an upper limit to the number of bits of delay possible in one-dimensional slow light structures that are based on linear optical response to the signal field. The limit is essentially the product of the length of the structure in wavelengths and the largest relative change in dielectric constant anywhere in the structure at any frequency of interest. It holds for refractive index, absorption or gain variations with arbitrary spectral or spatial form. It is otherwise completely independent of the details of the structure's design, and does not rely on concepts of group velocity or group delay

Experimentally determined aeroacoustic performance and control of several sonic inlets

Low speed wind tunnel tests were conducted to determine the aeroacoustic performance of several model sonic inlets. The results were analyzed to indicate how inlet aeroacoustic characteristics were affected by inlet design and operating conditions. A system for regulating sonic inlet noise reduction was developed and tested. Results indicate that pressure losses at forward velocity may be substantially less than those at static conditions. This is particularly true for translating centerbody inlets with the centerbody extended in the approach and landing position. Operation to simulated takeoff incidence angles of 50 degrees was demonstrated with good inlet performance. Inlet sound pressure level reduction was regulation was regulated to within approximately + or - 1 dB by controlling inlet surface static pressure measured at the diffuser exit

Pilot re-entry guidance and control

Operational problems of manually guided and controlled reentry vehicle

Inlet total pressure loss due to acoustic wall treatment

The effect of diffuser wall acoustic treatment on inlet total pressure loss was experimentally determined. Data were obtained by testing an inlet model with 10 different acoustically treated diffusers differing only in the design of the Helmholtz resonator acoustic treatment. Tests were conducted in a wind tunnel at forward velocities to 41 meters per second for inlet throat Mach numbers of .5 to .8 and angles of attack as high as 50 degrees. Results indicate a pressure loss penalty due to acoustic treatment that increases linearly with the porosity of the acoustic facing sheet. For a surface porosity of 14 percent the total pressure loss was 21 percent greater than that for an untreated inlet

The cave mouth antlions of Australia (Neuroptera: Myrmeleontidae)

Larvae of thirty one species of antlions (Neuroptera: Myrmeleontidae) belonging to eleven genera live in the protection of cave mouths or large rock overhangs in Australia. New taxa proposed here include the following three new genera: Australeon, Newleon, Speleon. The following twelve new species are described: Froggattisca kakadu; Froggattisca rennerensis; Newleon fragilis; Speleon cavernicolus; Speleon pilliga; Speleon yallingup; Stenoleon xanthopsis; Xantholeon cavernicolus; Xantholeon kakadu; Xantholeon newi; Xantholeon pallens; Xantholeon pentlandensis. Two cave species are transferred into a new genus becoming new combinations: Australeon illustris (Gerstaecker), Australeon manselli (New and Matsura). The small non-cave species previously placed in Stenoleon Tillyard are transferred to Bandidus Navás, becoming B. gradostriatus (New), B. copleyensis (New), B. grandithecus (New), and B. navasi (New), new combinations. All known species of six genera (Stenoleon Tillyard, Xantholeon Tillyard, Eophanes Banks and three new genera) are known only in cave mouths. Also, species of Heoclisis Navás, Froggattisca Esben Petersen, Glenoleon Banks, Heoclisis Navás and Myrmeleon Linnaeus contain species living in cave mouths. Two main types of caves are found in Australia; those with loose organic material and those with loose inorganic material. The cave habitat is divided into four zones and several subzones. Many species are restricted to one zone or another but species of Stenoleon may overlap zones. Discussions of the species and some of their biological requirements are provided. One new parasite record is given, an undetermined species of Echthrobacella Girault (Hymenoptera: Encyrtidae) reared from the larvae of Speleon yallingup Miller and Stange. Diagnoses or descriptions are given for all of these cave species including distributional data. Keys to the cave mouth inhabiting antlions of Australia (adults and larvae) are provided including a revised key to the Xantholeon Tillyard.Se documentan treinta uno especies en once géneros de Myrmeleontidae que viven en las entradas de cuevas en Australia y representan mas especies que en cualquier otra parte del mundo. Se describen tres genéros nuevos, Australeon, Newleon, y Speleon y doce especies nuevas: Froggattisca kakadu; Froggattisca rennerensis; Newleon fragilis; Speleon cavernicolus; Speleon pilliga; Speleon yallingup; Stenoleon xanthopsis; Xantholeon cavernicolus; Xantholeon kakadu; Xantholeon newi; Xantholeon pallens y Xantholeon pentlandensis. Dos especies son transferidas en un nueva género resultando en dos combinaciones nuevas: Australeon illustris (Gerstaecker) y Australeon manselli (New and Matsura). Tambien, cuatro especies en el género Stenoleon Tillyard son transferidas al género Bandidus Navas, resultando en cuatro combinaciones nuevas: B. gradostriatus (New), B. copleyensis (New), B. grandithecus (New) y B. navasi (New). Hay dos tipos de cuevas en Australia, unas con detritus orgánicos y otras con detritus principalmente inorgánicas. En algunas cuevas existen cuatro principales zonas de habitación. Todas las especies de cinco géneros (Eophanes Banks, Stenoleon Tillyard, Xantholeon Banks y tres nuevos géneros) están restringidas a las cuevas. Se da un registro nuevo para un parásito, Echthrobacella Girault (Hymenoptera: Encyrtidae) criada de Speleon yallingup Miller and Stange. Se presentan diagnoses o descripciones para todas las especies incluyendo datos sobre distribucion. Se presentan claves para los adultos y larvas de las especies que viven dentro de las cuevas en Australia, incyudendo una clave revisada del genero Xantholeon

Description of a new species of Paranthaclisis Banks from Florida (Neuroptera: Myrmeleontidae)

A new species of Paranthaclisis Banks, P. floridensis (Neuroptera: Myrmeleontidae), is described from Florida and compared to the other described species in the genus. Keys to the adults and larvae are provided.Se describe una nueva especie de Paranthaclisis Banks, P. floridensis (Neuroptera: Myrmeleontidae), de Florida y se la incluye en una clave para las otras especies descriptas del género. Se da una descripción del adulto y de la larva

Clausen's series 3F2(1) with integral parameter differences and transformations of the hypergeometric function 2F2(x)

We obtain summation formulas for the hypergeometric series 3 F 2(1) with at least one pair of numeratorial and denominatorial parameters differing by a negative integer. The results derived for the latter are used to obtain Kummer-type transformations for the generalized hypergeometric function 2 F 2(x) and reduction formulas for certain Kampé de Fériet functions. Certain summations for the partial sums of the Gauss hypergeometric series 2 F 1(1) are also obtained

Certain transformations and summations for generalized hypergeometric series with integral parameter differences

Certain transformation and summation formulas for generalized hypergeometric series with integral parameter differences are derived

Self stabilizing sonic inlet

An inlet suitable for a turbine engine in a STOL, VTOL or CTOL aircraft is described. A circumferentially extended slot is provided in the inner surface of the air inlet at the windward side and downstream of the throat region. The slot communicates with a circumferential plenum chamber formed in the front of the air inlet just behind the lip. Circumferentially extending rows of apertures are provided on the lip establishing two sets of apertures spaced circumferentially away from the slot in opposite directions. The slot removes the boundary layer from the critical portion of the diffuser to minimize or eliminate flow pressure loss or separations resulting from diffusion or tuning. The apertures are in a region of low static pressure on the lip of the inlet and serve as a source of suction to cause air flow into the slot