Mathematical programming for constrained minimal problems. Part 1 - Sequential gradient, restoration algorithm

Algorithm using gradient and restoration phases for constrained minimal problem

Low loss, high contrast optical waveguides based on CMOS compatible LPCVD processing: technology and experimental results

A new class of integrated optical waveguide structures is presented, based on low cost CMOS compatible LPCVD processing. This technology allows for medium and high index contrast waveguides with very low channel attenuation. The geometry is basically formed by a rectangular cross-section silicon nitride (Si3N4) filled with and encapsulated by silicon dioxide (SiO2). The birefringence and minimal bend radius of the waveguide is completely controlled by the geometry of the waveguide layer structures. Experiments on typical geometries will be presented, showing excellent characteristics (channel attenuation ≤ 0.1 dB/cm, IL ≤ 1.5 dB, PDL ≤ 0.2 dB, Bg ≤ 1×10-4, bend radius « 1 mm)

An Examination of the Combined Influences of Maternal Cognitions, Affect, and Behavior on Child Outcomes: A Model Comparison Approach

The primary goal of this study was to better understand the combined influence of maternal affect, cognitions and behavior on child internalizing and externalizing behavior. Specifically, mothers and children completed a series of measures designed to assess parenting stress, parenting efficacy, parenting behavior, and child internalizing and externalizing behavior. Participants were 115 mothers and their school-aged children who participated in an outpatient neuropsychological evaluation. Results suggest that child reported maternal warmth and control were important in influencing the development of internalizing behavior in children. Additionally, maternal parenting stress, warmth and control were found to be important influences in the development of externalizing behavior in children. The findings from this study demonstrate that the affective component of parenting (i.e., parenting stress) is the most powerful indicator of child external outcomes. Specifically, how stressed parents feel about being a parent significantly impacts not only how they behave toward their children but also directly affects how their children behave. Finally, an important finding of this research is the unique perspective parents and children have over internalizing and externalizing behaviors and their perceptions of maternal parenting behavior. More specifically, this study suggests that when examining internalizing behavior in children, child perceptions of parenting are the most important consideration; however, when examining externalizing behavior, both maternal and child perceptions of parenting are important to consider. This highlights the importance of understanding both mothers\u27 and children\u27s perceptions of parenting behavior in order to best understand the influence this has over the development of internalizing and externalizing outcomes in children

Ring resonator-based single-chip 1x8 optical beam forming network in LPCVD waveguide technology

Optical ring resonators (ORRs) are good candidates to provide continuously tunable delay in beam forming networks (BFNs) for phased array antenna systems. \ud Delay and splitting/combining elements can be integrated on a single optical chip to form an OBFN. A state-of-the-art 1×8 OBFN chip has been fabricated in LPCVD waveguide technology.\ud It is designed with 1 input and 8 outputs, between which a binary-tree topology is used. A different number of ORRs (up to 7) are cascaded for each output.\ud In this paper, the principle of operation is explained and demonstrated by presenting measurements on the 1×8 OBFN chip

Ring resonator-based Tunable Optical Delay Line in LPCVD Waveguide Technology

Optical circuits providing a time delay to signals modulated on optical carriers are considered important for optical communication systems and phased array antennas. A continuously tunable optical delay line is demonstrated in low-cost CMOS compatible LPCVD planar waveguide technology. The device consists of three cascaded ringresonator all-pass filters with fixed circumference of 2 cm (delay of 0.12 ns and FSR of 8.4 GHz). The measured group delay ranges from 0 ns up to 1.2 ns with a bandwidth of 500 MHz and delay ripple smaller than 1 ps, which is in accordance with the calculations

Optical beam forming for phased-array antennas

The activities of the Telecommunication Engineering (TE) group span the communications spectrum from copper cables, optical fibres, microwaves, radio and electromagnetic compatibility. Our research concentrates on optical signal processing and networks, mobile communications, microwave techniques and radiation from ICs and PCBs [1]. A considerable (and particularly interesting) part of it is related to optical beam forming for phased array antennas, using optical ring resonators.\ud In this article the theoretical basics and practical challenges of this interesting research topic will be summarized.\u

Phased array antenna steering using a ring resonator-based optical beam forming network

A novel beam steering mechanism for a phased array antenna receiver system is introduced. The core of the system is a ring resonator-based integrated optical beam forming network chip. Its principles are explained and demonstrated by presenting some measurement results. The system architecture around the chip is based on a combination of frequency down conversion, filter-based optical single sideband modulation and balanced coherent detection. It is proven that such an architecture has significant advantages with respect to a straightforward architecture using double sideband modulation and direct detection, namely relaxed bandwidth requirements on the optical modulators and detectors, reduced complexity and optical losses of the beam forming chip, and enhanced dynamic range

Broadband phased array antenna steering by means of coherent signal combining in an integrated ring resonator-based optical beamformer

A squint-free, continuously tunable optical beamformer for broadband phased array receive antennas is proposed. The complete system is demonstrated, including E/O and O/E conversions, and optical signal processing. The latter involves delay synchronization and coherent optical combining, which is performed in an integrated ring resonator-based optical beam forming network, realized in low-loss, CMOScompatible TriPleX technology. Successful combination of four beamformer input channels has been demonstrated by means of RF-to-RF measurements

Conformal phased array with beam forming for airborne satellite communication

For enhanced communication on board of aircraft novel antenna systems with broadband satellite-based capabilities are required. The installation of such systems on board of aircraft requires the development of a very low-profile aircraft antenna, which can point to satellites anywhere in the upper hemisphere. To this end, phased array antennas which are conformal to the aircraft fuselage are attractive. In this paper two key aspects of conformal phased array antenna arrays are addressed: the development of a broadband Ku-band antenna and the beam synthesis for conformal array antennas. The antenna elements of the conformal array are stacked patch antennas with dual linear polarization which have sufficient bandwidth. For beam forming synthesis a method based on a truncated Singular Value Decomposition is proposed

Novel ring resonator-based optical beamformer system and experimental results

A novel squint-free, continuously tunable beamformer mechanism for a phased array antenna system is proposed. It consists of filter-based optical single-sideband suppressed-carrier modulation, a fully integrated optical beam forming network using cascades of optical ring resonators as tunable delay elements, and balanced coherent optical detection. The proposed system brings advantages in optical bandwidth requirement, system complexity, and dynamic range, without introducing the problem of beam squint or limited tuning resolution. Some experimental results are presented in order to demonstrate the feasibility of the proposed concept