5,132 research outputs found
Long-Range Surface Plasmon Polariton Active Structures Based on Optically-Pumped Dye-Doped Polymer Gain Media
No full textSolid state organic gain medium using optically-pumped dye molecules doped in a polymer host is considered as the top cladding of a long-range surface plasmon polariton (LRSPP) structure to enable active plasmonic devices with interesting applications operating in the near-infrared.The gain media is a thin film of PMMA (poly (methyl methacrylate)) doped with ~ 0.9 wt% organic dye molecules of IR-140 and is pump optically using 8 nsec laser pulses at 810 nm to enable stimulated emission by excited dye molecules to the LRSPP mode at ~ 880 nm.The gain media was modeled through rate equations for a four-level energy system, relating the small signal gain coefficient to the dye photo-physical parameters, dye concentration and pump irradiance. Distributed Bragg reflector (DBR) and distributed feedback (DFB) lasers were proposed using Bragg reflectors based on modulation of the metal stripe width, forming a stepped-in-width Bragg grating in the LRSPP waveguide. Single mode surface plasmon DFB and DBR lasers were designed at 882 nm, by applying coupled-mode theory and transfer matrix method (TMM).The IR-140 doped PMMA gain medium was experimentally characterized. The maximum available material gain was identified for various pump intensities and two possible pump polarization in the gain media using the variable stripe length (VSL) method. The maximum available material gain agreed well with the theoretical gain modeling performed previously.The DFB lasers and passive Bragg gratings were fabricated in the microfabrication laboratories at Center for Research in Photonics in University of Ottawa. Main fabrication processes included electron beam lithography to create stepped-in-width Bragg grating patterns with sharp corners and edges, with features as small as 150 nm.Passive Bragg gratings were successfully characterized by my colleague showing a clear dip in the transmittance spectra (~ 40%) at the designed Bragg wavelength 882 nm.DFB lasers were characterized and successfully demonstrated a highly narrowed (FWHM ~ 0.2 nm) single mode lasing peak at 882 nm. The mode profile from the DFBs’ output facet was captured by an infrared camera showing a tiny bright spot surrounded with dim spontaneous emission
Statistical and modal analysis of surface pressure fluctuations in tornado-like vortices
No full textSurface pressure measurement is a general tool for evaluating wind flow qualitatively and quantitatively. Due to its complex temporal and spatial features, modal analysis is an interesting tool to be used for interpretation and discussion. The most common technique for modal representation is proper orthogonal decomposition (POD), also referred to as principal component analysis. However, it is believed that POD sometimes fails to extract meaningful features of the pressure field. To remove the non-physical POD modes and provide a closer physical description of the pressure field, an advanced method independent component analysis (ICA) is applied. Furthermore, these two methods are generalized in the frequency domain, called dynamic POD and dynamic ICA, to provide the temporal evolutions of coherent structures over the spatial domain. Modal analysis is used to isolate the different coherent structures in tornado-like vortices, e.g., wandering, vortex breakdown, and two-cell structure, and find the spectral characteristic of each phenomenon. Moreover, a comparison of modal analysis between the current paper and the previous paper on the velocity field {see Karami et al., ["Coherent structures in tornado-like vortices,"Phys. Fluids 31, 085118 (2019)]} presents new insight into the pressure-velocity correlation of the POD modes
Branched AND/OR graphs: Toward flexible and adaptable human-robot collaboration
No full textIn this work, we present a framework for human-robot collaboration allowing the human operator to alter the robot plan execution online. To achieve this goal, we introduce Branched AND/OR graphs, an extension to AND/OR graphs, to manage flexible and adaptable human-robot collaboration. In our study, the operator can alter the plan execution using two implementations of Branched AND/OR graphs for learning by demonstration, using kinesthetic teaching, and task repetition. Finally, we demonstrated the effectiveness of our framework in a defect spotting scenario where the operator supervises robot operations and modifies online the plan when necessary
Investigating 3D reconstruction of non-collaborative surfaces through photogrammetry and photometric stereo
No full text3D digital reconstruction techniques are extensively used for quality control purposes. Among them, photogrammetry and photometric stereo methods have been for a long time used with success in several application fields. However, generating highly-detailed and reliable micro-measurements of non-collaborative surfaces is still an open issue. In these cases, photogrammetry can provide accurate low-frequency 3D information, whereas it struggles to extract reliable high-frequency details. Conversely, photometric stereo can recover a very detailed surface topography, although global surface deformation is often present. In this paper, we present the preliminary results of an ongoing project aiming to combine photogrammetry and photometric stereo in a synergetic fusion of the two techniques. Particularly, hereafter, we introduce the main concept design behind an image acquisition system we developed to capture images from different positions and under different lighting conditions as required by photogrammetry and photometric stereo techniques. We show the benefit of such a combination through some experimental tests. The experiments showed that the proposed method recovers the surface topography at the same high-resolution achievable with photometric stereo while preserving the photogrammetric accuracy. Furthermore, we exploit light directionality and multiple light sources to improve the quality of dense image matching in poorly textured surfaces
Knowledge-based software engineering : a software quality management expert system prototype
No full textExpert system/Knowledge-based technology is a branch of the discipline of Artificial Intelligence. The purpose of this research is to examine whether this technology can be successfully applied to mainstream software engineering to improve the quality of software production. It is argued that software engineering is in crisis [1] and ES/KBS technology, though a relatively new technology, can assist in software engineering. The approach we take is to investigate the shortcomings of software engineering and outstanding characteristics of Expert/Knowledge-Based systems. Being a young discipline, software engineering provides a set of worthy research fronts amongst which is Knowledge-Based Software engineering. Reports of many successful knowledge-based systems, as applied to different domain, have encouraged us to examine software engineering issues which can be addressed by knowledge based techniques. Demands for high quality software systems are now on the increase, owing to the affordability of computer hardware created by breakthroughs in this technology. Currently, the software community cannot cope with this increased pressure. There is growing evidence to suggest that failed software systems are causing losses of revenue and competitiveness due to lack of quality.In order to address the quality issue and incorporate the advantages of Knowledge-based technology we devised the Quality Optimiser, discussed in [2], as our initial commitment. The type of knowledge to be included in the Quality Optimiser expert system overlaps largely with the SEI's Capability Maturity Model which is one of the research avenues tackling software quality. As a result, we have decided to focus on CMM as a suitable application domain area.</p
Data for: A Compressible Hyper-Viscoelastic Material Constitutive Model for Human Brain Tissue and the Identification of Its Parameters
No full textThe experimental mechanical response of the brain reported in the literatur
Chemical Variability in the Composition of Zhumeria majdae (Rech. F. & Wendelbo) Essential Oil According to Storage Time and Temperature
No full textZhumeria majdae (Rech. F. & Wendelbo) is an aromatic herb belonging to the Lamiaceae family, traditionally employed in the Persian medicine for the treatment of a wide number of diseases. In the present study, the chemical composition of Z. majdae essential oil obtained from the plant’s aerial features, and stored at various temperatures (refrigerator temperature 4 °C, freezer temperature −20 °C, and room temperature 20 ± 3 °C) and times (0, 3, 6, and 9 months) was studied. The essential oil was isolated through hydrodistillation, and its composition was evaluated by gas chromatography/mass spectrometry (GC/MS). The results showed that the composition of essential oils changed as a function of the various storage temperatures and times. Linalool (34.85–48.45%), camphor (27.09–39.17%), limonene (1.97–4.88%), and camphene (1.6–4.84%) made up the main volatile compounds which showed differences in their concentrations according to the various storage conditions. Notably, when compared to a non-stored treatment sample (analyzed immediately after essential oil collection), the amount of linalool and camphor increased in all samples stored in all conditions of temperature and time, with the exception of the samples stored for nine months at room temperature. On the other hand, limonene and camphene contents decreased during the storage treatments, showing that the highest content of these compounds occurred in the non-stored treatment. Essential oil storage at the freezer temperature and for three months storage time resulted in the highest average value of the major constituents, highlighting these as the best conditions for obtaining the highest content of the major compounds
Talent AndTalent Management In Organizations
No full textABSTRACT: The main aim of this paper is to develop a conceptual framework for literature on the
consequences of talented employees and talent management. Talent management is one of the most important
issues in all organizations. It is very important to identify the talented employees and use them in strategic jobs.
This article is to review near the past twenty years of the importance of using talents. At the result of this
research, provide the necessary information and knowledge in the field of discovering and employing valuecreation
and talent management process in the all organizations
Additional descriptions of Ameroseius aegyptiacus (NASR & ABOU- AWAD) and Ameroseius lanceosetis LIVSHITZ & MITROFANOV (Acari: Ameroseiidae), with a revised key to the ameroseiid mites of Iran
No full textHajizadeh, Jalil, Karami, Fatemeh, -A, A (2017): Additional descriptions of Ameroseius aegyptiacus (NASR & ABOU- AWAD) and Ameroseius lanceosetis LIVSHITZ & MITROFANOV (Acari: Ameroseiidae), with a revised key to the ameroseiid mites of Iran. Linzer biologische Beiträge 49 (2): 1323-1334, DOI: http://doi.org/10.5281/zenodo.541065
The variability of thymol and carvacrol contents reveals the level of antibacterial activity of the essential oils from different accessions of Oliveria decumbens
No full textOliveria decumbens (Apiaceae) is an aromatic herb traditionally employed in the Persian medicine for the treatment of infectious and gastrointestinal disorders. In the present study, we analyzed the chemical composition of essential oils obtained from different Iranian populations and evaluated their efficacy on a panel of human pathogens (Staphylococcus aureus and Escherichia coli), probiotic (Bacillus subtilis), and phytopathogens (Clavibacter michiganensis, Curtobacterium flaccumfaciens, Xanthomonas citri, and Agrobacterium tumefaciens). The gas chromatographic-mass spectrometry analysis put in evidence four main volatile constituents such as thymol (20.3–36.4%), carvacrol (18.8–33.1%), γ-terpinene (10.6–25.9%), and p-cymene (9.5–17.3%), though with significant variability from an essential oil to another. Notably, the oils from the populations sited in Nourabad Mamasani and Dehdasht showed the highest amount of the phenolic monoterpenes thymol (36.4 and 35.2%, respectively) and carvacrol (33.1 and 30.6%, respectively). The antibacterial activity of O. decumbens essential oils was assessed by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods, showing high activity for the samples from Nourabad Mamasani and Dehdasht populations exhibiting high level of the above phenolics. The obtained MIC and MBC values (mg/ml) were in the ranges 0.0625–2 mg/ml and 1–16 mg/ml, respectively. Noteworthy, in some cases, the antibacterial activity of O. decumbens essential oils was higher than that of chloramphenicol used as positive control. The average MBCs displayed by the O. decumbens samples showed that C. flaccumfaciens had the highest sensitivity to the essential oils. Based on these results, our work shed light on selected O. decumbens populations deserving proper breeding and cultivation strategies in order to warrantee production of bioactive essential oils to be used at pharmaceutical and agricultural level to combat several pathogens
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