Reliable Multi-Path Routing Schemes for Real-Time Streaming

In off-line streaming, packet level erasure resilient Forward Error Correction (FEC) codes rely on the unrestricted buffering time at the receiver. In real-time streaming, the extremely short playback buffering time makes FEC inefficient for protecting a single path communication against long link failures. It has been shown that one alternative path added to a single path route makes packet level FEC applicable even when the buffering time is limited. Further path diversity, however, increases the number of underlying links increasing the total link failure rate, requiring from the sender possibly more FEC packets. We introduce a scalar coefficient for rating a multi-path routing topology of any complexity. It is called Redundancy Overall Requirement (ROR) and is proportional to the total number of adaptive FEC packets required for protection of the communication. With the capillary routing algorithm, introduced in this paper we build thousands of multi-path routing patterns. By computing their ROR coefficients, we show that contrary to the expectations the overall requirement in FEC codes is reduced when the further diversity of dual-path routing is achieved by the capillary routing algorithm.Comment: Emin Gabrielyan, "Reliable Multi-Path Routing Schemes for Voice over Packet Networks", ICDT'06, International Conference on Digital Telecommunications, Cote d'Azur, France, 29-31 August 2006, pp. 65-7

The Lived Experiences of Four Professional Development Directors in Urban Public School Districts

This research study was conducted on four urban professional development directors. A qualitative research framework was embraced to hear four administrators describe their perceptions of professional development programs and the factors they believe impact teachers in their districts; as well as how the administrators describe their personal attributes contributing to their programs. The goal of my study was to expand the narrow research base concerning the lived experiences of urban professional development directors, whose voices and experiences can inform others about relevant issues and leading urban professional development programs. In order to create a stronger understanding of the director’s perceptions on leading urban professional development programs, this study examined constructed meanings through a narrative interpretive lens. This qualitative study utilized the authentic words of the participants to convey their story, as it yielded a rich representation of the thoughts depicted. Data was gathered through in-depth, open-ended interviews and semi-structured interviews through which the events, beliefs and perceptions molded the phenomenon under investigation. Analysis of the data transpired immediately after each interview. Analytic conclusions were formed by classifying ideas and statements from the data to determine that significant constructs, themes and patterns surfaced. The findings of this study produced the following as it connected to the voices of the four urban professional development directors and their perceptions of successful professional development programs: (1) multi-faceted professional development programs had to be created by each director; (2) the teacher was perceived as the dominant vehicle impacting student success; (3) programs that helped increase teacher confidence were a priority for each director. Two secondary themes emerged supporting the primary themes. The secondary themes were (1) strong strategic planning ability and (2) a high sense of accountability

Ferrate(VI), Ferrate(V), and Ferrate(IV) Oxidation of Microcystin-LR, Flumequine, and Sulfadiazine: Oxidized Products

Microcystin (MC-LR) is a potent toxin and its presence in drinking water create a serious risk to human health. This paper presents the degradation of MC-LR in water by iron-based molecules, ferrates (Fe^VIO4^2- , Fe^VO4^3- , and Fe^IVO4^4- ) at pH 7.0. The oxidized products (OPs) were analyzed at various concentrations of ferrate species. Product studies showed the fragmentation of the cyclic MC-LR by all ferrates, which varied with the concentration and the oxidation state of ferrates. Three predominant degradation pathways are proposed, involving hydroxylation and breakage of peptide bond of MCLR. The extent of hydroxylation of MC-LR by Fe^VI was more than by Fe^V and Fe^IV. Fe^VI oxidation has potential to generate OPs with low molecular weight. Additionally, three pH (4.0, 7.0 and 9.0) were investigated to learn their on three pathways of MC-LR by Fe^VI, Fe^V , and Fe^IV. Analysis of peak areas of OPs showed that acidic conditions greatly facilitated the hydroxylation by three ferrates compared with the neutral and basic pH. Antibiotics have recently attracted increasing concern worldwide due to their ubiquitous occurrence and negative ecological effects on aquatic organisms. This paper investigated the oxidation kinetics and mechanisms of sulfadiazine (SDZ), a representative sulfonamide, by Fe^VI. The results showed that the reaction followed the second-order kinetics, and the rate constants decreased with the increasing pH from 4.0 to 10.0. Eleven OPs of SDZ were identified, and three initial pathways were proposed, including SO2 extrusion, deamination, and hydroxylation, of which the involvement of SO2 extrusion was first demonstrated during FeVI oxidation of SDZ. In addition, the removal of flumequine (FLU), a representative fluoroquinolone antibiotic, by Fe^VI, Fe^V , and Fe^IV species and the effect of ammonia were studied. The results indicated that Fe^VI exhibited a higher capability for the elimination of FLU than Fe^V and Fe^IV. Furthermore, the presence of ammonia enhanced the removal efficiency of FLU by Fe^VI and Fe^V . The reason was proposed to be the formation of higher reactive Fe^VI -ammonia and Fe^V -ammonia complexes than un-complexed ferrate species. Mechanical analysis indicated that these complexes reacted faster at the double bond moiety of the quinolone ring of FLU

Multi-color and artistic dithering

A multi-color dithering algorithm is proposed, which converts a barycentric combination of color intensities into a multi-color non-overlapping surface coverage. Multi-color dithering is a generalization of standard bi-level dithering. Combined with tetrahedral color separation, multi-color dithering makes it possible to print images made of a set of non-standard inks. In contrast to most previous color halftoning methods, multi-color dithering ensures by construction that the different selected basic colors are printed side by side. Multi-color dithering is applied to generate color images whose screen dots are made of artistic shapes (letters, symbols, ornaments, etc.). Two dither matrix postprocessing techniques are developed, one for enhancing the visibility of screen motives and one for the local equilibration of large dither matrices. The dither matrix equilibration process corrects disturbing local intensity variations by taking dot gain and the human visual system transfer function into account. Thanks to the combination of the presented techniques, high quality images can be produced, which incorporate at the micro level the desired artistic screens and at the macro level the full color image. Applications include designs for advertisements and posters as well as security printing. Multi-color dithering also offers new perspectives for printing with special inks, such as fluorescent and metallic inks

N-Ink Printer Characterization with Barycentric Subdivision

Printing with a large number of inks, also called N-ink printing, is a challenging task. The challenges comprise spectral modelling of the printer, color separation, halftoning, and limitations of the amount of inks. Juxtaposed halftoning, a perfectly dot-off-dot halftoning method, has proven to be useful to address some of these challenges. However, for juxtaposed halftones, prediction of colors as a function of ink area-coverages has not yet been fully investigated. The goal of this paper is to introduce a spectral prediction model for N-ink juxtaposed-halftone prints. As the area-coverage domain of juxtaposed inks forms a simplex, we propose a cellular subdivision of the area-coverage domain using barycentric subdivision of simplexes. The barycentric subdivision provides algorithmically straightforward means to design and implement an N-ink color prediction model. Within the subdomain cells, the Yule-Nielsen spectral Neugebauer model is used for the spectral prediction. Our proposed model is highly accurate for prints with a large number of inks while requiring a relatively low number of calibration samples

Halftoning by rotating non-Bayer dispersed dither arrays

We propose a new operator for creating rotated dither threshold arrays. This new discrete one- to-one rotation operator is briefly explained. We analyze its application to different dispersed- dot dither arrays such as hexagonal dispersed dither arrays and 3X3 matrix-based Bayer- expanded dither arrays and compare the results with the ones obtained by rotating standard Bayer dither arrays. We show that the rotation operator introduced new lower-frequency components that, for example in the case of rotated dispersed-dot Bayer dither, produces a slight clustering effect, improving the tone reproduction behavior of the halftone patterns. In other cases, such as hexagonal dispersed dither, these new lower frequency components are responsible for strong interferences in the rotated halftone array. When applied to 3x3 matrix- based Bayer-expanded dither arrays, the rotation operator induces sequences of short horizontal and vertical patterns that have very good tone reproduction behavior in the dark tones. Besides their used in black and white printing, rotated dispersed-dot dither halftoning techniques have also been successfully applied to in-phase color reproduction on inkjet printers