Photonic access concentrator for ATM gigabit switching fabrics

In future broadband communication networks the interest for purely photonic switches is due to the bandwidth mismatch between optical transmission networks and electronic switching nodes. Photonic ATM switching fabrics mainly based on wavelength-switching stages are therefore being studied, to implement high capacity switches with also concentration, multiplexing and demultiplexing functions, using state-of-the-art photonic technology. The architecture of an ATM photonic access concentrator is described in this paper, illustrating the design and implementation of its basic subsystems, the traffic concentrator and the cell multiplexer. The design guidelines are outlined in detail referring to an example, where 128 user lines at 622 Mb/s are given access to 4 outlets at 2.488 Gb/s. The corresponding implementation, based on the systematic use of cell wavelength encoding, makes use either of well-known photonic components, such as Fabry-Perot filters, fiber delay lines, splitters and combiners, either of recently developed devices, like high-speed optical gates and tunable filters and lasers. Finally, the system feasibility is demonstrated presenting the results obtained on a reduced size and speed experimental setup of the cell multiplexer     

Vitamin C Spray Drying: Study of the Thermal Constraint

Temperature variation in the spray drying method has no effect on the ascorbic acid molecule. No chemical interaction between the colloidal silica and the ascorbic acid could be determined, but a physicochemical interaction “absorption” was determined. Colloidal silica improved the final yield of spray drying in proportion to its concentration. No polymorphic forms could be determined in the spray-dried ascorbic acid. Drug release from the ascorbic acid spray dried was found to be dependent on the Aerosil content: highest release rates were obtained with Aerosil.     

Differences between organic and schizophrenic groups on the Halstead-Reitan battery: A reply to Watson.

Questions C. G. Watson's (see PA, Vol 52:Issue 3) attempt to explain apparent inconsistencies in findings between his and the present authors' studies in terms of sample differences. Despite Watson's reanalysis of his data by matched pairs, he fails adequately to control for differences in chronicity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

10-Gb/s transmission of NRZ over 10000 km and solitons over 13500 km error-free in the same dispersion-managed system

A dispersion management scheme that is capable of supporting both dispersion-managed solitons and nonreturn-to-zero (NRZ) data formats as well as intermediate formats is demonstrated for error-free long-haul transmission at 10 Gb/s in excess of 9500 km. This experimental tool ran be used to directly compare the different data formats. Our results suggest that a format between standard solitons and standard NRZ, such as dispersion-managed solitons or phase-modulated NRZ, may have significant advantages.     

Non-uniform wavelets in electromagnetic scattering analysis

Non-uniform wavelets are constructed to benefit from both adaptively refined grids for modelling edge singularities and compression of moment matrices with wavelet bases. They are applied to the analysis of electromagnetic scattering problems     

Prediction and Measurement of Electron Density and Collision Frequency in a Weakly Ionised Pine Fire

Pine litter flame is a weakly ionised medium. Electron-neutral collisions are a dominant form of particle interaction in the flame. Assuming flame electrons to be in thermal equilibrium with neutrals and average electron-neutral collision frequency to be much higher than the plasma frequency, the propagation of microwaves through the flame is predicted to suffer signal intensity loss. A controlled fire burner was constructed where various natural vegetation species could be used as fuel. The burner was equipped with thermocouples and used as a cavity for microwaves with a laboratory quality network analyzer to measure wave attenuation. Electron density and collision frequency were then calculated from the measured attenuation. The parameters are important for numerical prediction of electromagnetic wave propagation in wildfire environments. A controlled pine litter fire with a maximum flame temperature of 1080 K was set in the burner and microwaves (8–10.5 GHz) were caused to propagate through the flame. A microwave signal loss of 1.6–5.8 dB was measured within the frequency range. Based on the measured attenuation, electron density and electron-neutral collision frequency in pine fire were calculated to range from 0.51–1.35?×?10¹⁶ m^?3 and 3.43–5.97?×?10¹⁰ s^?1 respectively.     

Triple corner reflector antenna and its performance in H-plane

An experimental investigation of a novel corner reflector antenna with improved performance is reported. The corner reflector antenna has been structurally modified by attaching two more reflector elements. The parameters such as the primary corner angle, position, width and angle of the secondary elements have significant effects on the H-plane radiation characteristics of the antenna. Certain symmetric configurations of this triple corner reflector (TCR) antenna provide sharp beams with a gain of the order of 3 dB over that of the conventional corner reflector (CR) antenna     

A 9-ns, 1.4-gigabyte/s, 17-ported CMOS register file

Advances in circuit and microarchitecture design have made it possible to develop a 9-ns, 17-ported register file which can support a full 1.4-gigabyte/s bandwidth. With 79000 transistors in a 1-μm CHMOS process, the 4 K register file is a major unit of a microprocessor, which is a 100-MOPS VLSI parallel processing component with an integrated communication unit. The benefit of increased system performance is realized since all connected functional units can receive full bandwidth operand supply. A brief introduction gives a conceptual framework to understand the architecture and bandwidth implications. Various techniques were used to optimize the macroarchitecture by modifying the register file's internal microarchitecture. All aspects of the design including read/write circuitry, cell stability, and special access cells are described     

The influence of temperature and humidity on the life-cycle of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

The development of Ephestia kuehniella was followed carefully on white flour at constant temperatures ranging from 7.5° to 31°C at humidities from 0 to 75% r.h. The lower limit of temperature for complete development was about 12°C although a few adults of a stock collected recently emerged at 10°C. Adults emerged at 28 but not at 31°C. Generally, development took longer and survival was poorer at 40 than at 70% r.h. However, at 20 and 25°C survival was good even at 15% r.h., and at 25°C, 18 out of 50 larvae reached the adult stage at a humidity near 0% r.h. Development was fastest at 25°C, 75% r.h., taking a mean of 74 days from oviposition to adult emergence.Oviposition occurred at 7.5 but not at 5°C. Mating was unsuccessful at 12.5°C. Eggs hatched at all temperatures between 12 and 31°C at every r.h. used. A few eggs from two field stocks hatched at 10°C but none did so at 7.5°C.At 12 C no larvae pupated at humidities below 70% r.h., and none pupated at 31°C at any humidity. Larval development was most rapid at 25°C, 75% r.h., taking about 60 days. The shortest mean pupal period, 9 days, occurred at 28°C, 70% r.h. In an experiment with field stocks, many larvae pupated at 10°C but none at 7.5°C.This study confirms E. kuehniella as essentially a temperate species that prefers heated premises such as bakeries and mills for rapid development. Its ability to develop on food at a low e.r.h. fits it further for life in flour mills.