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

Self-Configuring Universal Linear Optical Component

We show how to design an optical device that can perform any linear function or coupling between inputs and outputs. This design method is progressive, requiring no global optimization. We also show how the device can configure itself progressively, avoiding design calculations and allowing the device to stabilize itself against drifts in component properties and to continually adjust itself to changing conditions. This self-configuration operates by training with the desired pairs of orthogonal input and output functions, using sets of detectors and local feedback loops to set individual optical elements within the device, with no global feedback or multiparameter optimization required. Simple mappings, such as spatial mode conversions and polarization control, can be implemented using standard planar integrated optics. In the spirit of a universal machine, we show that other linear operations, including frequency and time mappings, as well as non-reciprocal operation, are possible in principle, even if very challenging in practice, thus proving there is at least one constructive design for any conceivable linear optical component; such a universal device can also be self-configuring. This approach is general for linear waves, and could be applied to microwaves, acoustics and quantum mechanical superpositions

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

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

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

Antlions of Hispaniola (Neuroptera: Myrmeleontidae)

Twelve extant species of antlions are known from Hispaniola including four new species (Eremoleon petrophila, Eremoleon phasma, Purenleon nunezi, Purenleon woodruffi) and one new genus (Peruveleon). Five New World species are transferred into Peruveleon resulting in new combinations: Peruveleon bruneri (Alayo), Peruveleon camposi (Banks), Peruveleon dolichogaster (Navás), Peruveleon dorsalis (Banks), Peruveleon indiges (Walker). Vella fallax haitiensis Smith is considered a new synonym of Vella eggerti Esben-Petersen. Descriptions and records for the species are provided as well as keys to the adults and larvae. The larvae of eleven species were found and reared.Se documentan doce especies de Myrmeleontidae de Hispaniola incluyendo cuatro especies nuevas (Eremoleon petrophila, Eremoleon phasma, Purenleon nunezi, Purenleon woodruffi) y un género nuevo (Peruveleon). Cinco especies son transferidos al género Peruveleon resultando nuevas combinaciones: Peruveleon bruneri (Alayo), Peruveleon camposi (Banks), Peruveleon dolichogaster (Navás), Peruveleon dorsalis (Banks), Peruveleon indiges (Walker). Vella fallax haitiensis Smith es considerado como un sinonimo nuevo de Vella eggerti Esben-Petersen. Se proporcionan descripciones y registros para las especies y claves para los adultos y larvas. Las larvas de once especies fueron descubiertas y asociadas con adultos