617 research outputs found
Low-energy standby-sparing for hard real-time systems
No full textTime-redundancy techniques are commonly used in real-time systems to achieve fault tolerance without incurring high energy overhead. However, reliability requirements of hard real-time systems that are used in safety-critical applications are so stringent that time-redundancy techniques are sometimes unable to achieve them. Standby sparing as a hardware redundancy technique can be used to meet high reliability requirements of safety-critical applications. However, conventional standby-sparing techniques are not suitable for low-energy hard real-time systems as they either impose considerable energy overheads or are not proper for hard timing constraints. In this paper we provide a technique to use standby sparing for hard real-time systems with limited energy budgets. The principal contribution of this work is an online energy management technique which is specifically developed for standby-sparing systems that are used in hard real-time applications. This technique operates at runtime and exploits dynamic slacks to reduce the energy consumption while guaranteeing hard deadlines. We compared the low-energy standby-sparing (LESS) system with a low-energy time redundancy system (from a previous work). The results show that for relaxed time constraints, the LESS system is more reliable and provides about 26% energy saving as compared to the time-redundancy system. For tight deadlines when the time redundancy system is not sufficiently reliable (for safety-critical application), the LESS system preserves its reliability but with about 49% more energy consumptio
Suicide as a Passage Through Silent Issues: A Case Study of Suicide Attempt Survivors in Tehran Zeinab Kouchakian Alireza Kaldi Alireza Mohsenitabrizi
No full textSuicide as a Passage Through Silent Issues: A Case Study of Suicide Attempt Survivors in Tehran Zeinab Kouchakian[1] , Alireza Kaldi[2] , Alireza Mohsenitabrizi[3] Received: 06/4/2018 Accepted: 22/12/2018 Abstract Suicide, as a conscious action in hurting oneself causing death, is among the social issues of human society that is increasing day by day. Suicide epidemiological studies inIran have shown that attempting suicide and committing an act of suicide is increasing. Using a qualitative approach, and based on the grounded theory of the social and cultural reasons behind suicide attempt, the current study aims to investigate the interaction between the person who commits suicide and his/her family, group and society as well as its relationship with suicide attempt. Through this, the present study seeks to find a more vivid image of the relationship between [1]. Ph.D. student of Cultural Sociology, Islamic Azad University, Science and Research Branch of Tehran. [email protected] [2]. Professor of Sociology, Faculty of Social Welfare and Rehabilitation Sciences, Tehran, Iran (Corresponding Author). [email protected] [3]. Professor of Sociology, Faculty of Social Sciences, University of Tehran, Iran [email protected]
Coded aperture imaging of nuclear fusion in the plasma focus device
No full textThe Coded Aperture Imaging (CAI) technique has been used to image the deuterium-deuterium (D-D) fusion source in the NX2 plasma focus (PF) device, using protons emitted from the D(d,p)T reaction. CAI is a form of multiplexed pinhole imaging which uses many small pinholes arranged in specific patterns so as to obtain images with the good spatial resolution expected for a small pinhole, together with high brightness and signal-to-noise ratio (SNR) associated with a much larger open aperture. Our theoretical study of CAI led us to the conclusion that for extended sources, such as the PF pinch, coded mask patterns of relatively low open fraction (i.e. significantly less than 50%) are optimal. Therefore the mask patterns used in our experimental work are based on Singer cyclic difference sets. Monte Carlo simulations of CAI and pinhole imaging were performed in order to validate our theoretical SNR formulae and test our decoding algorithm. CR-39 polymer nuclear track detectors were used to register the ~3 MeV protons emitted from the PF pinch. As an additional test of the CR-39 detector scanning procedures, theoretical formulae, and CAI decoding algorithm, various source shapes were simulated experimentally using a 226Ra alpha particle source. As anticipated, the obtained alpha particle CAI images were found to be considerably better than the corresponding single-pinhole images. Significantly, this work represents the first application of the CAI technique to imaging the fusion source in a plasma focus device.The time-integrated neutron yield and anisotropy for each NX2 plasma focus shot were measured using fast- neutron detectors based on the production of radioactive 6He via the 9Be(n,α)6He reaction. The newly fabricated detectors comprise a beryllium metal sheet sandwiched between two large-area xenon-filled proportional counters. A methodology was developed for calculating the absolute neutron response function of these beryllium activation detectors, based on: the 9Be(n,α)6He reaction cross-section, energy calibration of the proportional counters, and numerical simulations (using MCNP5) of neutron and beta-particle interactions.In one series of experiments, five CAI cameras with identical masks were employed simultaneously: one placed on-axis (0°) and four at 45° to the plasma focus axis at the distances of 10.3 cm and 4.9 cm from the source respectively, to investigate the spatial distribution of D-D fusion in the NX2 PF device operated in pure D2 gas and with a PF bank energy of 1.6 kJ. These conditions represent the neutron-optimized regime, for which the neutron yield is typically 1-3×108 n/shot. In a second series of experiments, two larger coded masks: mask-1345 (91×15 array and 341 holes each 0.3 mm side) and mask-4680 (104×45 arrays and 585 holes each 0.27 mm side) were placed at 90° to the plasma focus axis to investigate the fusion source in pure deuterium and deuterium-krypton admixture working gases. The number of proton tracks registered on the CR-39 detectors per shot was typically (1-3)×105. The results clearly show the different size, density and shape of the fusion source in pure D2 and D2-Kr admixture operation. For this second series of experiments, an x-ray pinhole imaging system with suitable filtering was employed simultaneously to record the associated xray images of the hot dense pinched plasma column for comparison with the fusion source images. A plastic scintillation detector was used to measure the time-resolved neutron signal, while the time-resolved hard x-ray pulse was measured using both cesium-iodide and barium-fluoride scintillation detectors.The results show little apparent correlation between the shape of the D-D fusion source and the corresponding soft x-ray image of the plasma pinch. For pure D2 discharges the proton CAI images show a reasonably symmetrical “cigar-shaped” fusion source surrounding the pinch column, without any appreciable indication of m = 0 or m = 1 plasma instabilities. Soft x-ray emission from the pinch column is much stronger for D2-Kr admixture operation than for pure D2 operation, and micro-pinches are frequently present within the main pinch column. Despite this, there are again no discernable indications of plasma instabilities in the associated proton CAI images. Proton CAI images show that the D-D fusion source is much narrower (i.e. of smaller diameter) for D2-Kr admixture operation of the NX2 than it is for pure D2 operation. It is concluded that a collective mechanism of deuteron acceleration occurs throughout the length of the pinch column in the NX2 device, and therefore the fusion is distributed rather evenly around the pinch column. Although m = 0 instabilities in the pinch column may initiate deuteron acceleration, the fast deuterons and resulting fusion are not concentrated within, or around, m = 0 instabilities
Semi-rigid floor-to-wall connections using side-framed lightweight steel structures : Concept development
No full textAuthor statement Alireza Bagheri Sabbagh: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Writing – original draft, Visualization, Shahabeddin Torabian: Conceptualization, Methodology, Validation, Investigation, Resources, Writing – review & editing, Visualization.Peer reviewe
Crossing the mirror into maternal waters: the ethics and aesthetics of Becoming-other in Ella Hickson’s The Writer (2018)
No full textThe past two decades of contemporary British drama have been marked by an upsurge of interest in the exploration of the ethics, aesthetics and politics of authorship along with the relational dynamics among the author, the work and audience/reader. One of the latest and paradigmatic examples of this trend is Ella Hickson’s The Writer (2018), a play informed by a queer feminist sensibility and distinguished by its aesthetics, its form, and its political critique of theatre as an institute underpinned by phallogocentric and heteronormative discourses. Accordingly, the essay will demonstrate how the queering of gender and genre are indelibly intertwined in the play. The Writer queers conventional theatrical form not only by deconstructing its “economy” and “forms” of hegemonic subjectivity, expression, and desire; but also by incorporating a surreal scene and various metatheatrical moments – to develop a more evental (or feminine) form characterised by formal transgression, abstraction, and excess. The Writer queers gender by pondering the dynamics of an evental love-sex relationship between the female writer (the protagonist) and her female lover along with a surreal experience of intimacy between the writer and mythical Semele. To effectively ponder the thematic and formal preoccupations of The Writer, this essay develops a nuanced conceptual framework whose premises include Irigaray’s “the female imaginary”, Deleuze’s “becoming-other”, Cixous’s “écriture feminine”, Lyotard’s “the figural” and Derrida’s “chora”
Deep Brain Stimulation (DBS) and Implant-friendly (IF) Mode Calculator
No full textRepository includes MATLAB codes. Raw input and and output files may be requested by emailing the author. The code that supports the findings of this study is openly available at https://github.com/AliSaMRI/DBS_IF_Mode_CalculatorThe purpose of this study is to present a strategy to calculate the implant-friendly (IF) excitation modes—which mitigate the radiofrequency (RF) heating at the contacts of deep brain stimulation (DBS) electrodes—of multi-channel RF coils at 7T.
Methods:
An induced RF current on an implantable electrode generates a scattered magnetic field whose left-handed circularly polarizing component (B1+) is approximated using a -mapping technique and subsequently utilized as a gauge for the electrode’s induced current. Using this approach, the relative induced currents due to each channel of a multi-channel RF coil on the DBS electrode were calculated. The IF modes of the corresponding multi-channel coil were determined by calculating the null space of the relative induced currents. The proposed strategy was tested and validated for unilateral and bilateral commercial DBS electrodes (directional lead, Infinity DBS system, Abbott Laboratories) placed inside a uniform phantom by performing heating and imaging studies on a 7T MRI scanner using a 16-channel transceive RF coil.
Results:
Individual IF modes nor shim solutions obtained from IF modes did not induce significant temperature increase when used for a high-power Turbo Spin Echo sequence. In contrast, shimming with the scanner’s toolbox (i.e., based on per-channel B1+ fields) resulted in a more than 2°C temperature increase for the same amount of input power.
Conclusion:
A strategy for calculating the IF modes of a multi-channel RF coil is presented. This strategy was validated using a 16-channel RF coil at 7T for unilateral and bilateral commercial DBS electrodes inside a uniform phantom.Sadeghi-Tarakameh, Alireza; DelaBarre, Lance; Zulkarnain, Nur Izzati Huda; Harel, Noam; Eryaman, Yigitcan. (2023). Deep Brain Stimulation (DBS) and Implant-friendly (IF) Mode Calculator. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/h56h-bd77
Dynamics of erythrocytes, vesicles and capsules in shear flow: the role of membrane bending stiffness and membrane viscosity
No full textThree-dimensional numerical simulations using immersed boundary/front-tracking
method are considered to study the dynamics and deformation of microscopic deformable cells with elastic and viscoelastic membranes suspended in linear shear flow. The objective in this thesis is to understand the complex fluid/structure interaction problem for membrane-bound soft matter in dilute suspensions. The numerical model includes all essential properties of the cell membrane, namely, the resistance against shear deformation, area dilatation, and bending, as well as the viscosity difference between the cell interior and suspending fluids. In addition, the Kelvin–Voigt viscoelastic model is incorporated to account for the effect of membrane viscosity. Our numerical technique is able to simulate complex dynamics of vesicles, capsules, and red blood cells in the tank-treading, breathing, trembling, and tumbling modes. A detailed comparison of the numerical results for vesicles is made with various theoretical models and experiments. It is found that the applicability of the theoretical models is limited to quasi-spherical vesicles. We show that near the transition between the tank-treading and tumbling dynamics, both the vacillating-breathing-like motion characterized by a smooth ellipsoidal shape, and the trembling-like motion characterized by a highly deformed shape are possible. We also present phase diagrams of the single red blood cell dynamics in linear shear flow. We find that the cell dynamics is often more complex than the well-known tank-treading, tumbling, and swinging motion and is characterized by an extreme variation of the cell shape. Identifying such complex shape dynamics termed here as breathing dynamics, is the focus of this study. Further, we find a very good agreement between our numerical and the theoretical and experimental results on the tank-treading frequency of red blood cells, which is often measured in experiments and used to extract the mechanical properties of the cell. A comprehensive analysis of the influence of the membrane viscosity on buckling, deformation and dynamics is given for initially spherical or oblate capsules. The major finding here is that the membrane viscosity leads to buckling in the range of shear rates in which no buckling is observed for capsules with purely elastic membrane.Ph. D.Includes bibliographical referencesIncludes vitaby Alireza Zarif Khalili Yazdan
Ultralight Membrane Structures Toward a Sustainable Environment
No full textThe building construction industry is the largest anthropogenic source of pollution, with massive energy consumption and substantial CO2 emissions. Lightweight tension structures allow the simultaneous implementation of several sustainable strategies by using recyclable low-carbon structural membranes offering a greener alternative to glass and other cladding materials. Their efficient structural load-bearing mechanisms result in significant weight savings in buildings and a drastic reduction of the environmental impact associated with material production, transportation, use, and disposal. A subgroup of lightweight materials, structural fabrics, and foils has been gaining popularity among designers and architects in recent years because of their desirable features such as high stiffness, strength, ductility, durability, and functional properties. While these structural membranes open new crucial perspectives for the clean energy transition and have been recently employed worldwide, their full potential is still limited by the lack of construction codes, advanced optimization tools, and comprehensive viscous-thermo-mechanical constitutive models. This chapter aims to foster the design of membrane structures by presenting their basic principles and recent advancements in the field. It covers the design approaches, employed materials and efforts in their characterization and modeling, implications on the sustainability of the built environment, current challenges, and future pathways from both academic research and engineering design viewpoints.Team Marcel Sluite
Knowledge Type Identification in API Documentation
No full text<p>This release contains the source code and instruction on how to obtain the dataset to reproduce the results presented in the following paper</p>
<pre><code>@inproceedings{FMM19,
title={On Using Machine Learning to Identify Knowledge in API Reference Documentation},
author={Fucci, Davide and M. Alizadeh B., Alireza and Maalej, Walid},
booktitle={27th ACM Joint European Software Engineering Conference and Symposium on the Foundations of Software Engineering},
pages={103--112},
year={2019},
doi={10.1145/3338906.3338943}
organization={IEEE}
}
</code></pre>
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