Generic simulation models of communication systems

2002 ◽  
Author(s):  
A. Cohen ◽  
R. Mrabet
Keyword(s):  
Communication Systems ◽  
Simulation Models

scholarly journals Modeling and Simulation of MIMO Mobile-to-Mobile Wireless Fading Channels

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Gholamreza Bakhshi ◽  
Reza Saadat ◽  
Kamal Shahtalebi
Keyword(s):  
Fading Channels ◽  
Communication Systems ◽  
Cross Correlation ◽  
Reference Model ◽  
Simulation Models ◽  
Space Time ◽  
Closed Form Expression ◽  
Scattering Model ◽  
Analysis And Design ◽  
Special Cases

Analysis and design of multielement antenna systems in mobile fading channels require a model for the space-time cross-correlation among the links of the underlying multipleinput multiple-output (MIMO) Mobile-to-Mobile (M-to-M) communication channels. In this paper, we propose the modified geometrical two-ring model, a MIMO channel reference model for M-to-M communication systems. This model is based on the extension of single-bounce two-ring scattering model for flat fading channel under the assumption that the transmitter and the receiver are moving. Assuming single-bounce scattering model in both isotropic and nonisotropic environment, a closed-form expression for the space-time cross-correlation function (CCF) between any two subchannels is derived. The proposed model provides an important framework in M-to-M system design, where includes many existing correlation models as special cases. Also, two realizable statistical simulation models are proposed for simulating both isotropic and nonisotropic reference model. The realizable simulation models are based onSum-of-Sinusoids (SoS)simulation model. Finally, the correctness of the proposed simulation models is shown via different simulation scenarios.

scholarly journals Improving the Performance of MIMO Fading Channel Simulators Using New Parameterization Method: تحسين أداء نموذج محاكاة الخفوت للأقنية MIMO باستخدام خوارزميات جديدة لحساب المعاملات

2020 ◽  
Vol 4 (4) ◽  
Author(s):  
Omar Yousuf Alzoubi
Keyword(s):  
Modeling And Simulation ◽  
Fading Channels ◽  
Communication Systems ◽  
Simulation Models ◽  
Original Method ◽  
Doppler Spread ◽  
Mimo Channel ◽  
Isotropic Scattering ◽  
Modified Method ◽  
Lp Norm

The research aims to modeling and simulation of fading channels for providing necessary tool to develop communication systems. The modeling and simulation of MIMO fading channels is studied for both isotropic- and non-isotropic scattering cases for one-ring model, so in this context, three methods for MIMO simulation channel models are studied: Extended Method of Exact Doppler Spread (EMEDS), Modified Method of Equal Areas (MMEA) and Method Lp-Norm (LPNM). Three new methods are also suggested to design the simulation model of MIMO channel: Modified Extended Method of Exact Doppler Spread (MEMEDS), New Modified Method of Equal Areas (NMMEA) and Modified Lp-Norm method (MLPNM). The performance of each proposed method is compared with the original method by comparing the statistical properties ACF, 2D-CCF and CF of both reference and simulation models.

Correlation of Pore Structure and Permeability by SEM-Image Analysis

1990 ◽  
Vol 48 (1) ◽  
pp. 428-429
Author(s):  
C. A. Callender ◽  
Wm. C. Dawson ◽  
J. J. Funk
Keyword(s):  
Image Analysis ◽  
Pore Structure ◽  
Imaging System ◽  
Pore Space ◽  
Simulation Models ◽  
Image Analyzer ◽  
Imaging Data ◽  
Sem Images ◽  
Thin Sections ◽  
Rock Types

The geometric structure of pore space in some carbonate rocks can be correlated with petrophysical measurements by quantitatively analyzing binaries generated from SEM images. Reservoirs with similar porosities can have markedly different permeabilities. Image analysis identifies which characteristics of a rock are responsible for the permeability differences. Imaging data can explain unusual fluid flow patterns which, in turn, can improve production simulation models.Analytical SchemeOur sample suite consists of 30 Middle East carbonates having porosities ranging from 21 to 28% and permeabilities from 92 to 2153 md. Engineering tests reveal the lack of a consistent (predictable) relationship between porosity and permeability (Fig. 1). Finely polished thin sections were studied petrographically to determine rock texture. The studied thin sections represent four petrographically distinct carbonate rock types ranging from compacted, poorly-sorted, dolomitized, intraclastic grainstones to well-sorted, foraminiferal,ooid, peloidal grainstones. The samples were analyzed for pore structure by a Tracor Northern 5500 IPP 5B/80 image analyzer and a 80386 microprocessor-based imaging system. Between 30 and 50 SEM-generated backscattered electron images (frames) were collected per thin section. Binaries were created from the gray level that represents the pore space. Calculated values were averaged and the data analyzed to determine which geological pore structure characteristics actually affect permeability.

Plant peptide hormone signalling

2015 ◽  
Vol 58 ◽  
pp. 115-131 ◽  
Author(s):  
Ayane Motomitsu ◽  
Shinichiro Sawa ◽  
Takashi Ishida
Keyword(s):  
Communication Systems ◽  
Cell Communication ◽  
Peptide Hormone ◽  
Peptide Hormones ◽  
Target Cells ◽  
Signalling Molecules ◽  
Receptor Complexes ◽  
Environmental Responses ◽  
Plant Life Cycle ◽  
Multicellular Organisms

The ligand–receptor-based cell-to-cell communication system is one of the most important molecular bases for the establishment of complex multicellular organisms. Plants have evolved highly complex intercellular communication systems. Historical studies have identified several molecules, designated phytohormones, that function in these processes. Recent advances in molecular biological analyses have identified phytohormone receptors and signalling mediators, and have led to the discovery of numerous peptide-based signalling molecules. Subsequent analyses have revealed the involvement in and contribution of these peptides to multiple aspects of the plant life cycle, including development and environmental responses, similar to the functions of canonical phytohormones. On the basis of this knowledge, the view that these peptide hormones are pivotal regulators in plants is becoming increasingly accepted. Peptide hormones are transcribed from the genome and translated into peptides. However, these peptides generally undergo further post-translational modifications to enable them to exert their function. Peptide hormones are expressed in and secreted from specific cells or tissues. Apoplastic peptides are perceived by specialized receptors that are located at the surface of target cells. Peptide hormone–receptor complexes activate intracellular signalling through downstream molecules, including kinases and transcription factors, which then trigger cellular events. In this chapter we provide a comprehensive summary of the biological functions of peptide hormones, focusing on how they mature and the ways in which they modulate plant functions.

Instruction Using Augmentative and Alternative Communication Supports: Description of Current Practices by Speech-Language Pathologists Who Work With Children With Autism Spectrum Disorder

2020 ◽  
Vol 29 (2) ◽  
pp. 586-596 ◽  
Author(s):  
Kaitlyn A. Clarke ◽  
Diane L. Williams
Keyword(s):  
Autism Spectrum Disorder ◽  
Augmentative And Alternative Communication ◽  
Communication Systems ◽  
Diagnostic Category ◽  
Children With Autism ◽  
Autism Spectrum ◽  
Spectrum Disorder ◽  
Alternative Communication ◽  
Speech Language Pathologists ◽  
Processing Differences

Purpose The aim of this research study was to examine common practices of speech-language pathologists (SLPs) who work with children with autism spectrum disorder (ASD) with respect to whether or not SLPs consider processing differences in ASD or the effects of input during their instruction. Method Following a qualitative research method, how SLPs instruct and present augmentative and alternative communication systems to individuals with ASD, their rationale for method selection, and their perception of the efficacy of selected interventions were probed. Semistructured interviews were conducted as part of an in-depth case report with content analysis. Results Based on completed interviews, 4 primary themes were identified: (a) instructional method , (b) input provided , (c) decision-making process , and (d) perceived efficacy of treatment . Additionally, one secondary theme, training and education received , was identified . Conclusions Clinicians reported making decisions based on the needs of the child; however, they also reported making decisions based on the diagnostic category that characterized the child (i.e., ASD). The use of modeling when teaching augmentative and alternative communication to individuals with ASD emerged as a theme, but variations in the method of modeling were noted. SLPs did not report regularly considering processing differences in ASD, nor did they consider the effects of input during instruction.

Thoughts on Grammar Intervention in AAC

2008 ◽  
Vol 17 (2) ◽  
pp. 43-49 ◽  
Author(s):  
Marc Fey
Keyword(s):  
Language Impairment ◽  
Specific Language Impairment ◽  
Augmentative And Alternative Communication ◽  
Communication Systems ◽  
Target Language ◽  
Alternative Communication ◽  
Physical Limitations ◽  
Communication Needs ◽  
Communication Interventions ◽  
Planning Intervention

Abstract In this article, I propose that, for several reasons, grammar should be an early focus of communication interventions for young children using augmentative and alternative communication (AAC) systems. The basic goals for such programs should be to facilitate the child's comprehension of the language of the community, or the target language, thus leading the way to literacy, and to foster the child's use of symbol combinations that mirror the grammatical patterns of speaking children acquiring the target language, even if they cannot be fully grammatically complete. I introduce five principles that underlie most successful approaches to grammar interventions with children with specific language impairment. My initial attempts to apply these principles to interventions with children with complex communication needs indicate that they may be of considerable value to clinicians planning intervention programs. On the other hand, the challenges posed by the intellectual and physical limitations of many AAC users and their communication systems make it necessary to modify at least Principle 5 if the basic goals of intervention are to be met.

Helping the General Education Team Support Students Who Use AAC

2012 ◽  
Vol 21 (3) ◽  
pp. 82-91 ◽  
Author(s):  
Carole Zangari
Keyword(s):  
Academic Achievement ◽  
General Education ◽  
Communication Skills ◽  
Communication Systems ◽  
General Education Teachers ◽  
Practice Opportunities ◽  
Support Students ◽  
Successful Students

Abstract To be successful, students who use AAC and attend general education classes require extensive supports and frequent practice with their communication systems. In this article, I explore the challenges faced by educational teams and discuss strategies for helping general education teachers, paraprofessionals, and others provide the AAC learning and practice opportunities these students need to maximize their communication skills and academic achievement.

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