703 research outputs found
PKS: A photogrammetric key-frame selection method for visual-inertial systems built on ORB-SLAM3
No full textKey-frame selection methods were developed in the past years to reduce the complexity of frame processing in visual odometry (VO) and visual simultaneous localization and mapping (VSLAM) algorithms. Key-frames help increasing algorithm's performances by sparsifying frames while maintaining its accuracy and robustness. Unlike current selection methods that rely on many heuristic thresholds to decide which key-frame should be selected, this paper proposes a photogrammetric-based key-frame selection method built upon ORB-SLAM3. The proposed algorithm, named Photogrammetric Key-frame Selection (PKS), replaces static heuristic thresholds with photogrammetric principles, ensuring algorithm’s robustness and better point cloud quality. A key-frame is chosen based on adaptive thresholds and the Equilibrium Of Center Of Gravity (ECOG) criteria as well as Inertial Measurement Unit (IMU) observations. To evaluate the proposed PKS method, the European Robotics Challenge (EuRoC) and an in-house datasets are used. Quantitative and qualitative evaluations are made by comparing trajectories, point clouds quality and completeness and Absolute Trajectory Error (ATE) in mono-inertial and stereo-inertial modes. Moreover, for the generated dense point clouds, extensive evaluations, including plane-fitting error, model deformation, model alignment error, and model density and quality, are performed. The results show that the proposed algorithm improves ORB-SLAM3 positioning accuracy by 18% in stereo-inertial mode and 20% in mono-inertial mode without the use of heuristic thresholds, as well as producing a more complete and accurate point cloud up to 50%. The open-source code of the presented method is available at https://github.com/arashazimi0032/PKS
Expression analysis of protein inhibitor of activated STAT (PIAS) genes in IFNβ-treated multiple sclerosis patients [Corrigendum]
No full textTaheri M, Azimi G, Sayad A, et al. J Inflamm Res. 2018;11:457–463.On page 457, Author list and Correspondence, the last author’s name was misspelt. The correct name is Soudeh Ghafouri-Fard.Read the original articl
Ali Banisadr
No full textAli Banisadr's first major monograph delves into the Iranian painter's influences and practice. Preeminent Iranian-American artist Ali Banisadr's canvases depict a complex swirl of action and abstracted figuration across a stagelike picture plane. Varied histories inform these paintings, ranging from the artist's synesthesia, to Persian miniatures, to the multi-figure works of Brueghel and Bosch, and the gestural imaginations of Willem de Kooning and Max Ernst. Born in Tehran in 1976, Ali Banisadr grew up during the Islamic revolution and the eight-year Iran-Iraq War. In 1988, he and his family emigrated to Turkey and then to California. In 2000, he moved to New York City where he currently lives and works. --Publisher's descriptio
Isolation of resonance in acoustic backscatter from elastic targets using adaptive estimation schemes
No full textThe problem of underwater target detection and classification from acoustic backscatter is the central focus of this paper. It has been shown that at certain frequencies the acoustic backscatter from elastic targets exhibits certain resonance behavior which closely relates to the physical properties of the target such as dimension, thickness, and composition. Several techniques in both the time domain and frequency domain have been developed to characterize the resonance phenomena in acoustic backscatter from spherical or cylindrical thin shells. The purpose of this paper is to develop an automated approach for identifying the presence of resonance in the acoustic backscatter from an unknown target by isolating the resonance part from the specular contribution. An adaptive transversal filter structure is used to estimate the specular part of the backscatter and consequently the error signal would provide an estimate of the resonance part. An important aspect of this scheme lies in the fact that it does not require an underlying model for the elastic return. The adaptation rule is based upon fast Recursive Least Squares (RLS) learning. The approach taken in this paper is general in the sense that it can be applied to targets of unknown geometry and thickness and, further, does not require any a priori information about the target and/or the environment. Test results on acoustic data are presented which indicate the effectiveness of the proposed approach.The work of M. R. Azimi-Sadjadi was supported by the ASEE-ONR program under the High Area Rate Recon. Project. The work of J. Wilbur and G. J. Dobeck was supported by the ONR
Bioassay-directed isolation of quaternary benzylisoquinolines from Berberis integerrima with bactericidal activity against Brucella abortus
No full textBerberis integerrima Bonge. (Syn: Berberis densiflora Boiss. & Buhse) is a shrub widely distributed in Middle East and central part of Asia. An ethnobotanical study revealed that indigenous and tribal people in Iran use B. integerrima root decoction for treatment of brucellosis. Therefore, the aim of this study was bioassay directed isolation of antibacterial compounds from this plant based on their in vitro bactericidal activity against Brucella abortus. Briefly, the ethanol extract of B. integerrima was fractioned and subjected to preliminary antibacterial screening tests against Brucella. The more active fraction (Fr.3) was subjected to purification by repeated chromatography systems. Quaternary benzylisoquinoline alkaloids including columbamine, palmatine, berberine, and jatrorhizine were four main components identified in the selected active fraction. Except for berberine which is reported before, palmatine, columbamine and jatrorhizine are isolated for the first time from this plant. Anti-brucellosis properties of isolated compounds 1-4 were studied against B. abortus under different test conditions. In minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) results, jatrorhizine (4) showed more antibacterial activity with MIC and MBC of 0.78 and 1.56 μg/mL, respectively. In both agar well diffusion and disk diffusion ANOVA results showed that there were statistically significant differences between compounds 1-4 versus placebo in all of the tested concentration (P <0.001). In conclusion, all of four alkaloids showed potent antibacterial activity against B. abortus but jatrorhizine and columbamine with free hydroxyl group on C-3 or C-2 showed more activity than palmatine and berberine without any free hydroxyl group on their structures. The antibacterial effects of columbamine (15 μg/mL) and jatrorhizine (15 μg/mL) were comparative to streptomycin (10 μg/mL) as standard drug which candidate them for more pharmacological researches to find new antibacterial agents against brucellosis
1938 revisited? Should doors open wider to Syrian refugees?
No full textDoes it seem that every time the world watches refugees flee violence and persecution while politicians claim their country can\u27t possibly take in asylum seekers, we lamentingly claim that the world will never again turn its back on these people.
And yet the next time we seem people streaming out of a war zone with nothing but their families and the shirts on their back we forget the promise we made the last time this happened?
For a world that promised \u27Never Again\u27 after World War II, how much have we actually learned from the handling of refugee crises of the past? Are we making the same mistakes over and over again?
Do you see echoes of the treatment of Jews fleeing the Holocaust in government rhetoric about refugees from Syria and Iraq? And if so, what explains this short-sightedness?
Guests
Dai Le, Founder of DAWN (Diverse Australasian Women’s Network)
Professor Klaus Neumann, Historian at Swinburne University and author of Across the Seas: Australia\u27s Response to Refugees: A History
Akram Azimi, Sociologist at the University of Western Australia and 2013 Young Australian of the Yea
Wave-Induced Currents Within Mangrove Forest
No full textMangroves are tidal trees commonly observed along the sheltered shorelines of most tropical (from equator to 23.5° North and South latitude) and few subtropical (23.5° to 40° North and South latitude) countries. These plants are adapted to loose wet soils, saline habitats and periodic tidal submergence. With more attention paid into the approach of building with nature, natural coastal defence strategies are gaining more importance as an asset in addressing the coastal squeeze that is prevalent not only in urban areas, but also in agriculture and industrial areas that are located along the coastline. Mangroves are receiving more attention due to their coastal protective role against wave and hydrodynamic forcings as well as their ability to adapt to sea level rise. Mangrove vegetation attenuates and damps the hydrodynamics forcings by providing obstacles to the flows and creating drag. To date and to the knowledge of the author, no study has been conducted on interaction of the wave-induced currents with mangrove vegetation. This lack of relevant studies may be due to the fact that mangrove forests and the foreshore in front of the mangroves are usually of very gently sloping bed (varying in order of 1:300 to 1:1500). This means that in order to conduct physical model experiments to study wave-induced current within a mangrove forest, a very large wave basin is required in order to conduct modelling without using a very large scale factor difference between prototype and model. This is to ensure that the relevant processes are representing prototype as closely as possible, as well as to be measureable. Numerical modelling of the interaction of wave-induced current with mangrove vegetation is yet to be conducted due to the lack of measured data for validation, both field as well as experimental measurements. An experiment by Hulsbergen (1973) was selected as validation data for current study. The main objective of the study is to understand the difference of nearshore processes for (stationary) tidal gradient-driven and oblique wave-driven current for both with and without mimic mangrove vegetation. The scope of the study involves desktop analysis of the main validation data and other relevant and similar experiments, assessment of reliability of Delft3D for the study, validation against measured data, and simulation of various hydraulic conditions for condition with mangrove forest. Among questions answered in this study are the extent of wave-induced longshore current damping within mangrove forest, the significance of wave-induced longshore current within mangrove forest, the effects of bed slope and mangrove density on wave-induced current and the extent of model’s reliability for current study. It was shown that the damping of wave-induced longshore current is more than 80% and the contribution of waveinduced current to the total velocity can be more than 70%. Of course, both of the above was specific to the bathymetry, mangrove properties and hydraulic conditions specified within current study. Furthermore, it was shown that bed slope and mangrove density affect wave-induced longshore current within the mangrove forest. It was also found that current model setup has its limitations.Civil Engineering | Hydraulic Engineering | Coastal Engineerin
Change in Attitude in Renal Function in Major Beta Thalassemia
No full textThalassemia is a multisystemic disease in the field of hemolysis and chronic anemia caused by the erythropoietic disorder. The severe effects of iron overload from continuous blood transfusion iron chelators side effects, and involvement of multiple organs in thalassemias such as heart failure, liver, and endocrine dysfunction can all affect kidney function. Although there has been much debate about changes in renal function in thalassemia for many years, the presence of hyperfiltration and ultimately, decreased renal function in almost all studies. It seems for the researchers to look beyond kidney function in a thalassemia perspective, because of secretory biomarkers of proximal tubular renal cells that are sensitive to pathologic agents, which may be a good indicator of the courses of treatment and prognosis of patients. Future studies will be sooner or later.
*Corresponding Author: Malihe Najafpour; Email: [email protected]
Please cite this article as: Malaki M, Najafpour M, Talebi M, Azimi A. Change in Attitude in Renal Function in Major Beta Thalassemia. Arch Med Lab Sci. 2020;6:1-5 (e24). https://doi.org/10.22037/amls.v6.3305
Wheel-soil interaction modelling for rover simulation and analysis
No full textAppropriate modelling of the interaction between wheel and terrain is a key element in simulating wheeled mobile robots and analyzing their functionality on soft terrain. In this thesis, two modelling approaches, with their implementation in a multi-body dynamics environment and their experimental validation, are introduced. The first approach is based on well-established semi-empirical terramechanics models. The multi-pass effect is considered in the implementation by storing terrain deformation and changes in hardening of soil under the wheel. A high-resolution height-field (HF) is used to model the terrain surface, with relevant information stored in the HF vertices. A novel framework is developed for implementation of this model in a multi-body dynamics environment. For every wheel in contact with soft soil, unilateral contact constraints are added to the solver in the normal direction. Terramechanics forces in the tangent plane and the resistant moment are formulated as set-valued functions associated with kinematic constraints on their complementary variables. The new formulation leads to the dynamics representation in the form of a linear complementarity problem. The properties of these constraints are set based on the soil reactions determined from the semi-empirical terramechanics model, at every time-step of the simulation. With this approach, fast and stable simulation is achieved. In the second approach, normal and shear stress distributions in the contact area are determined using continuum mechanics with a computationally efficient technique compared to finite element modelling. The author proposes a velocity field in the vicinity of the contact area motivated by the physical nature of the problem. Using this field, the incremental changes to the stress field are determined by resorting to classical elasto-plasticity theory and an appropriate constitutive relation for soil. As opposed to finite element approaches, which model the soil in contact with the wheel as a high-resolution mesh, our approach focuses on the wheel-soil contact patch only. This localized representation provides the basis for fast wheel-soil interaction modelling. By combining this approach with a height-field as terrain representation, elasto-plastic soil deformation and changes in the hardening state of soil are directly captured. In addition, because of the elasto-plastic representation for soil, energy dissipation during soil compaction is directly captured. The dynamic slip-sinkage behaviour of the wheel and the semi-elliptical shape of the normal stress distribution under the wheel are natural outcomes of the proposed model. The results obtained from the proposed approach are compared with experimental data available in the literature, which show good agreement between the model and experiments under various ranges of wheel slippage and loading conditions.Moreover, an extensive set of experiments was conducted using a version of the Juno rover (Juno II), owned by the Canadian Space Agency (CSA). The analysis of the results shows good agreement between the experimental rover behaviour and the simulation runs using both models developed.Afin de simuler et d'analyser les mouvements de robots mobiles (rovers) sur terrain déformable, il est essentiel de correctement modéliser les interactions entre les roues du véhicule et le terrain. Dans cette thèse, deux approches de modélisation seront présentées et analysées, avec leurs mises en œuvre dans un environnement de simulation en temps réel. La première approche est basée sur un modèle semi-empiriques de mécanique des sols. L'effet du passage répété d'un véhicule sur le terrain est pris en compte par le stockage de la déformation du terrain et du durcissement du sol sous les roues. Un champ de hauteur (Height Field) à haute résolution est utilisé pour modéliser la surface du terrain; les informations nécessaires sont stockées dans les sommets du champ de hauteur. Une approche originale est développée pour la mise en œuvre dans l'engin de simulation. Pour chaque roue en contact avec le sol mou, une contrainte de contact unilatéral est ajouté au solveur pour la direction normal au mouvement. Les forces dans le plan tangent, issus de la mécanique des sols, et la résistance au moment sont traités comme des fonctions multivaluées associées à des contraintes cinématique pour les variables complémentaires. Cette nouvelle formulation conduit à une représentation dynamique sous forme d'un problème de complémentarité linéaire. Les propriétés des contraintes sont définies en fonction des réactions du sol, calculées par le modèle semi-empirique à chaque pas de simulation. Avec cette approche, une simulation rapide et stable est obtenue. Dans la seconde approche, la répartition des contraintes normales et de cisaillement dans la zone de contact est déterminée en utilisant la mécanique des milieux continus avec une technique de calcul efficace par rapport à la modélisation par éléments finis. Nous proposons l'utilisation d'un champ de vitesses au voisinage de la zone de contact, dans une approche motivée par la nature physique du problème. Avec ce champ de vitesse, les changements progressifs du champ de contraintes sont calculées en recourant à la théorie d'élasto-plasticité classique et à une relation de comportement appropriée pour les sols. Contrairement aux approches par éléments finis, qui modélisent le sol en contact avec la roue comme un maillage haute résolution, notre approche est axée uniquement sur l'aire de contact roue-sol. En combinant cette approche avec un champ de hauteur comme représentation du terrain, la déformation élasto-plastique du sol et les changements dans le durcissement du sol sont directement pris en compte. En outre, en raison de la représentation élasto-plastique du sol, la dissipation d'énergie au cours du compactage du sol est aussi directement prise en compte. Le comportement dynamique de compaction et de glissement de la roue et la forme semi-elliptique de la répartition des contraintes normales sous la roue sont les résultats naturels du modèle proposé. Les résultats obtenus par cet approche sont comparés à des données disponibles dans des études expérimentales, et montre un bon accord avec la théorie pour un large domaine de valeur de glissement et de charge. En outre, un vaste ensemble d'expériences ont été menées en utilisant une version du rover Juno (Juno II) de l'Agence spatiale canadienne (ASC). L'analyse des résultats montre un bon accord entre le comportement expérimental des rovers et des simulations utilisant les deux modèles développés
Design of residential complexes with emphasize on the role of roof on reducing energy consumption
No full textDocumentos apresentados no âmbito do reconhecimento de graus e diplomas estrangeirosHuman life from the beginning and during all eras has been directly related to the production and consumption of energy. Technology advancement is dependent on energy and its consumption, Limited reserves of fossil fuels, as well as environmental pollution resulted from their consumption has stimulated issues related to environment and energy. Thus, in recent years, using renewable energy sources is a major concern of modern human because in addition of being renewable, they are very diverse too. That is why that now a day and in industrialized countries this issue is followed seriously. And in this way, especially in the construction sector, much attention has been paid to designing and developing samples proportionate to this objective. Thus, energy saving in these buildings can have a significant impact in reducing consumption of fossil energies
Roof is one of the main components of the building which is generally neglected by building designers. Through examining thermal performance and tracking their changes during different hours and seasons and direct using of solar source, one can achieve effective ways to reform component design, and found out that such an architectural element to what extent can be effective in loss of energy or indirect energy saving, especially in urban areas.
The research investigates thermal behavior of roof shape, according to the mean radiant temperature which is one component of the thermal comfort, in sloping roofs of residential complexes in the Karaj City. (The dominant form of the ceiling in the study area).
At first ,in this research ,library studies and analytical happened ,and in the next section, computational simulation as research methodology are applied.In this section alternativesare modeled and compute based on four types of roofs with different angles. At the end, the final results of analysis, show the best form and angle for reduce the waste of energy in this area that are used in final design
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