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Analysis of Solidification in Spray Atomized and Codeposited Metal-matrix Composites Part Ⅰ: Atomization

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Journal of Materials Science & Technology 1995年第3期11卷 79-90页

作者： V.Erukhimovitch and J.Baram(Materials Engineering Department, ben-gurion university of negev, Beer-Sheva, Israel) ben-gurion univ of negev Beersheva Israel

Fluid mechanics, heat transfer and liquid-to-solid phase transformation are assessed in optimizing the spray atomization and codeposition process parameters for size refinement and microstructural uniformity of the deposited material. Atomization gas velocities, atomized droplets velocities, convective heat transfer coefficients, thermal histories of the solidifying droplets, freezing rates, fraction solid evolution and solid-liquid interface propagation velocity are calculated. The influence, on the deposit microstructural features, of process parameters like the atomization gas pressure, the pouring tube orifice diameter, the geometrical features of the atomization device,the potency of , pre-existing or injected as reinforcement, nucleation sites, the wetting angle between the liquid melt bnd impurity particles acting as preferred nucleation sites, the in-flight distance of the solidifying droplets in the atomization chamber, i5 evaluated. As a result of the evaluation, appropriate choice of the adjustable process parameters for the production of powders and/or deposits with desired grain size and microstructure, can be made.

关键词： Co Figure Atomization Analysis of Solidification in Spray Atomized and Codeposited Metal-matrix Composites Part

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On helical behavior of turbulence in the ship wake

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Journal of Hydrodynamics 2013年第1期25卷 83-90页

作者： GOLBRAIKH Ephim EIDELMAN Alexander SOLOVIEV Alex Physics Department Ben-Gurion University of the Negev Mechanical Engineering Department Ben-Gurion University of the Negev Oceanographic Center NOVA South eastern University

Turbulent ship wake conservation at a long distance is among unsolved problems at present. It is well known that far wakes have a vortical structure and slowly expand with distance. As was obtained by Dubrovin et al., slow expansion of the wake may be related to the distribution of turbulent viscosity in it. In our work we study the effect of helicity in the wake on the behavior of turbulent viscosity. Taking into account the helical nature of the wake, we can clarify the difference between turbulence inside and outside the wake on the one hand and slowing down of its expansion with time on the other hand.

关键词： ship wake turbulent ship wake helical turbulence

Three-dimensional single particle tracking using 4π self-interference of temporally phase-shifted fluorescence

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Light(Science & Applications) 2023年第3期12卷 415-424页

作者： Leanne Maurice Alberto Bilenca Biomedical Engineering Department Ben-Gurion University of the Negev1 Ben Gurion BlvdBe’er-Sheva84105Israel Ilse Katz Institute for Nanoscale Science and Technology Ben-Gurion University of the Negev1 Ben Gurion BlvdBe’er-Sheva84105Israel

Single particle tracking in three dimensions is an indispensable tool for studying dynamic processes in various disciplines,including material sciences,physics,and biology,but often shows anisotropic three-dimensional spatial localization precision,which restricts the tracking precision,and/or a limited number of particles that can be tracked simultaneously over extended *** we developed an interferometric,three-dimensional fluorescence single particle tracking method based on conventional widefield excitation and temporal phase-shift interference of the emitted,high-aperture-angle,fluorescence wavefronts in a greatly simplified,free-running,triangle interferometer that enables tracking of multiple particles at the same time with<10-nm spatial localization precision in all three dimensions over extended volumes(~35×35×2μm^(3))at video rate(25 Hz).We applied our method to characterize the microenvironment of living cells and up to~40μm deep in soft materials.

关键词： materials particle dimensions

Optimized guided mode resonant structure as thermooptic sensor and liquid crystal tunable filter

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Chinese Optics Letters 2009年第8期7卷 667-670页

作者： I.Abdulhalim Department of Electrooptic Engineering Ben Gurion University of the Negev

Applicability of guided mode resonant structures to tunable optical filtering and sensing is demonstrated using nematic liquid crystals. As a sensor, a minimum refractive index detectivity of 10^-5 is demonstrated while as a tunable filter, tunability range of few tens of nanometers with 2-nm bandwidth is presented. The optimum design is achieved by maximizing the evanescent field region in the analyte which maximizes the overlap integral. The device can be operated in reflection or transmission modes at normal incidence. It can also be operated at a single wavelength by measuring the angular profile of the light beam.

关键词： mode Optimized guided mode resonant structure as thermooptic sensor and liquid crystal tunable filter

X-Ray Photoelectron Spectroscopy Study of the Metal/Cermet Interface

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Chinese Physics Letters 2001年第1期18卷 94-96页

作者： LU Hua SHEN Dian-Hong XUE Qi-Kun M.Polak N.Froumin Department of Materials Engineering Ben-Gurion University of the NegevIsrael

Interfacial reactions between aluminium and polycrystalline cermet TiC_(0.6) were investigated using x-ray photoelectron spectroscopy,Auger electron spectroscopy and x-ray *** was found that titanium exists in two chemical *** carbide and oxide of titanium can be detected simultaneously,and the atomic ratio of Ti:C:O is 5:3:*** suggests that TiC^(0.6) is a Ti-oxycarbide or oxygenated TiC composite:Ti_(5)C_(3)O_(2)(TiO_(2)+4TiC_(0.75)).When Al is deposited in vacuum on the Ti-oxycarbide surface,the active Al atoms react chemically only with TiO_(2) at room temperature,but not with Tico.75 in *** reaction products are Al2O3 and theintermetallic compound Als *** the Al/TiC_(0.6) interface at 750℃,Al reacts also with TiC_(0.75) to form a brittle Al_(4)C_(3) phase.

关键词： carbide diffraction. intermetallic

Yaw stability control for a rear double-driven electric vehicle using LPV-H∞ methods

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Science China(Information Sciences) 2018年第7期61卷 82-94页

作者： Yonathan WEISS Liron I.ALLERHAND Shai AROGETI Department of Mechanical Engineering Ben-Gurion University of the Negev Bio Catch

This paper presents a new yaw stability controller for a rear double-driven electric vehicle. A linear parameter varying(LPV) model of the vehicle is formulated using longitudinal speed measurement and tire cornering stiffness estimation. The LPV model is then utilized to design a gain-scheduled H∞controller with guaranteed stability. Results from simulations, performed with Car Sim, show that the new controller improves the vehicle performance and handling even in extreme maneuvers and that it is robust to model parameter uncertainties.

关键词： yaw stability control electric vehicle torque vectoring H_∞ control gain-scheduling

DNA damage and neurodegeneration:the unusual suspect

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Neural Regeneration Research 2017年第9期12卷 1441-1442页

作者： Daniel Stein Debra Toiber Department of Life Sciences Ben-Gurion University of the Negev The Zlotowski Center for Neuroscience Ben-Gurion University of the Negev

Neurodegenerative diseases are caused by the loss of neuro- nal cells. As neurons deteriorate, a patient may experience relatively mild symptoms such as failing to name objects and people. However, with the progression of the disease, symp- toms worsen resulting in loss of independence and a sense of＂loss of oneself＂. Finally, the patient dies from a variety of complications.

关键词： DNA damage and neurodegeneration:the unusual suspect

Sniffing Bacteria with a Carbon-Dot Artificial Nose

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Nano-Micro Letters 2021年第7期13卷 138-152页

作者： Nitzan Shauloff Ahiud Morag Karin Yaniv Seema Singh Ravit Malishev Ofra Paz-Tal Lior Rokach Raz Jelinek Department of Chemistry Ben Gurion University of the Negev84105 Beer ShevaIsrael Department of Biotechnology Engineering Ben Gurion University of the Negev84105 Beer ShevaIsrael Chemistry Department Nuclear Research CenterNegevP.O.Box 900184190 Beer ShevaIsrael Department of Software and Information System Engineering Ben-Gurion University of the NegevBeer ShevaIsrael Ilse Katz Institute for Nanotechnology Ben Gurion University of the Negev84105 Beer ShevaIsrael

Continuous,real-time monitoring and identification of bacteria through detection of microbially emitted volatile molecules are highly sought albeit elusive *** introduce an artificial nose for sensing and distinguishing vapor molecules,based upon recording the capacitance of interdigitated electrodes(IDEs)coated with carbon dots(C-dots)exhibiting different *** of the C-dot-IDEs to volatile molecules induced rapid capacitance changes that were intimately dependent upon the polarities of both gas molecules and the electrode-deposited *** deciphered the mechanism of capacitance transformations,specifically substitution of electrode-adsorbed water by gas molecules,with concomitant changes in capacitance related to both the polarity and dielectric constants of the vapor molecules *** C-dot-IDE gas sensor exhibited excellent selectivity,aided by application of machine learning *** capacitive C-dot-IDE sensor was employed to continuously monitor microbial proliferation,discriminating among bacteria through detection of distinctive“volatile compound fingerprint”for each bacterial *** C-dot-IDE platform is robust,reusable,readily assembled from inexpensive building blocks and constitutes a versatile and powerful vehicle for gas sensing in general,bacterial monitoring in particular.

关键词： Carbon dots Bacterial detection Bacterially emitted volatile molecules Capacitive gas sensors Gas polarity

Habitat use by mountain nyala Tragelaphus buxtoni determined using stem bite diameters at point of browse, bite rates, and time budgets in the Bale Mountains National Park, Ethiopia

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Current Zoology 2013年第6期59卷 707-717页

作者： Solomon A. TADESSE Butt P. KOTLER Mitriani Department for Desert Ecology Blaustein Institutes for Desert Research Ben-Gurion University of the NegevMidreshet Ben-Gurion 84990 Israel

We studied the habitat use of mountain nyala Tragelaphus buxtoni in the northern edge of the Bale Mountains Na- tional Park, Ethiopia. The aims of this study were to：（1） measure and quantify habitat-specific stem bite diameters of mountain nyala foraging on common natural plant species in two major habitat types （i.e. grasslands versus woodlands）, and （2） quantify the bite rates （number of bites per minute） and the activity time budgets of mountain nyala as functions of habitat type and sex-age category. We randomly laid out three transects in each habitat type. Following each transect, through focal animal obser- vations, we assessed and quantified stem diameters at point of browse （dpb）, bite rates, and time budgets of mountain nyala in grasslands versus woodlands. Stem dpb provide a measure of natural giving-up densities （GUDs） and can be used to assess fora- ging costs and efficiencies, with greater stem dpb corresponding to lower costs and greater efficiencies. The results showed that stem dpb, bite rates, induced vigilance, and proportion of time spent in feeding differed between habitats. In particular, mountain nyala had greater stem dpb, higher bite rates, and spent a greater proportion of their time in feeding and less in induced vigilance in the grasslands. In addition, adult females had the highest bite rates, and the browse species Solanum marginatum had the greatest stem dpb. Generally, grasslands provide the mountain nyala with several advantages over the woodlands, including of- fering lower foraging costs, greater safety, and more time for foraging. The study advocates how behavioural indicators and natural GUDs are used to examine the habitat use of the endangered mountain nyala through applying non-invasive techniques. We conclude that the resulting measures are helpful for guiding conservation and management efforts and could be applicable to a number of endangered wildlife species including the mountain nyala .

关键词： Behavioural indicators Bite rates Mountain nyala Natural giving-up densities Non-invasive techniques Stem bite diameters Vigilance