•FA and ZS utilize synergistically through ambient temperature geopolymerization.•Low reactivity of fly ash at ambient condition is overcome by addition of ZS.•Slag addition has modified the ...reactivity and more C-(A)-S-H gel is formed.•Compact microstructure with well bridged particles is observed in ZS rich blends.•Paving blocks confirm IS 15658 specification and meet US-EPA 1311 standard.
The potential for practical application of fly ash, zinc slag and their blends for geopolymer synthesis at ambient temperature have been investigated in this paper. Fly ash is an alumino-silicate byproduct suitable for geopolymer reaction, but its low reactivity at ambient condition is the restriction of its bulk utilization. Above limitation can be overcome by blending with zinc slag (ZS). Additionally, ZS contains heavy and toxic metals (Pb, Zn, Cr, Cd, As), which can be stabilize in Al-Si based geopolymer network structure. Isothermal conduction calorimetry (ICC) is used to monitor the geopolymer reaction with time. Slag rich specimens are characterized with higher rate of reaction with augmented peak. The mineralogy and microstructure of the geopolymers have been examined through X-ray diffraction and scanning electron microscope. The detected chief reaction product is N-(C)-A-S-H and C-(N)-A-S-H11(where, N=Na2O, C=CaO, A=Al2O3, S=SiO2 and H=H2O) type hydrated gel. Continual improvement of compressive strength of the geopolymers with increasing slag content is explained with higher degree of reaction, formation of more reaction products and development of compact microstructure. According to toxicity characteristic leaching procedure (TCLP), toxic metals leaching is within permissible limit. Paver blocks using 40−80 wt% ZS has been developed, which meets IS 15,658: 2006 standard and comply with US-EPA specification.
Isothermal conduction calorimetry has been used to study the reaction kinetics of early geopolymerization of fly ash. Fly ash particles were subjected to react with NaOH solution in 2:1 ratio at ...isothermal temperatures of 34, 39, 45, 52, and 60 °C. The reaction kinetic parameters such as activation energy, rate of reaction, and pre-exponential function were calculated using the rate of heat evolution data. It is observed that the geopolymerization reaction followed a nucleation and growth mechanism. The activation energy obtained from an Arrhenius plot was around ~100 kJ mol
−1
.
This work focuses on gainful utilization of low reactive fly ash at ambient temperature into alkali-activated binder with the addition of another industrial waste silico-manganese (SiMn) slag. ...Granulated SiMn slag (GSS) percentage was gradually increased into fly ash-based reference batch. The influence of slag on reactivity of the blends was monitored by isothermal conduction calorimetry. Reactivity was improved with increasing slag content. The structural reorganizations of the resultant binder were detected by peak shifting in Fourier transform infrared spectroscopy study. The positional change of the hump in X-ray diffraction analysis was due to structural rearrangement of the binder. The calcium-rich hydrated product formation was increased with slag inclusion. The fly ash-derived geopolymer gel (N–A–S–H) was coexisted with slag activated gel (C–S–H/C–A–S–H), (where N = Na
2
O, A = Al
2
O
3
, C = CaO, S = SiO
2
, and H = H
2
O) in the blend matrix. EDX analysis confirmed the variation in Si/Al, Ca/Si, and Na/Al ratios of the binder with the alteration of reaction products. The development of better compressive strength in slag-rich binder attributed with the formation of Ca-rich gel phases.
TERS v2.0: An improved version of TERS Nath, S.
Computer physics communications,
November 2009, 2009-11-00, 20091101, Letnik:
180, Številka:
11
Journal Article
Recenzirano
We present a new version of the semimicroscopic Monte Carlo code “TERS”. The procedure for calculating multiple small angle Coulomb scattering of the residues in the target has been modified. ...Target-backing and residue charge-reset foils, which are often used in heavy ion-induced complete fusion reactions, are included in the code.
Program title: TERS v2.0
Catalogue identifier: AEBD_v2_0
Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEBD_v2_0.html
Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland
Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html
No. of lines in distributed program, including test data, etc.: 7309
No. of bytes in distributed program, including test data, etc.: 1 219 555
Distribution format: tar.gz
Programming language: C
Computer: The code has been developed and tested on a PC with Intel Pentium IV processor.
Operating system: Linux
RAM: About 8 Mbytes
Classification: 17.7
External routines: pgplot graphics subroutine library 1 should be installed in the system for generating residue trajectory plots. (The library is included in the CPC distribution file.)
Catalogue identifier of previous version: AEBD_v1_0
Journal reference of previous version: Comput. Phys. Comm. 179 (2008) 492
Does the new version supersede the previous version?: Yes
Nature of problem: Recoil separators are employed to select and identify nuclei of interest, produced in a nuclear reaction, rejecting unreacted beam and other undesired reaction products. It is important to know what fraction of the selected nuclei, leaving the target, reach the detection system. This information is crucial for determining absolute cross section of the studied reaction.
Solution method: Interaction of projectiles with target nuclei is treated event by event, semimicro-scopically. Position and angle (with respect to beam direction), energy and charge state of the reaction products are calculated by Monte Carlo method. Trajectory of each nuclei inside the separator is then calculated by ion optical transfer matrix method. Ratio of the number of trajectories completing their journey up to the detection system to the total number of trajectories is a direct measure of absolute transmission efficiency of the separator.
Reasons for new version: The method for calculating mean squared scattering angle (〈ϑ〉2), used earlier 2, was found to be inadequate particularly for low energy heavy residues. Energy loss of beam in the target-backing foil and energy loss of residues in the charge-reset foil (wherever used) needed to be taken into account for better matching of simulated residue parameters with measurements.
Summary of revisions:1.A new method 3 for calculating multiple small angle Coulomb scattering of residues in the target has been adopted. The change is incorporated in function Weibull() in the program ters_pti2.c.2.Isotopically enriched targets are made on a thin backing foil (usually made of carbon) quite often. Energy loss of beam in the backing foil (assuming beam is made to pass through the backing foil first, which is the usual practice) need to be taken into account. This calls for minor changes in the input file ters_pti2.inp. Following is the modified list of input parameters in this file with explanation.Zp, Ap, Zt, At –Atomic no. and mass no. of projectile and target.Ep –Projectile energy MeV in laboratory.BeamSpot, TarThick –Dia. mm of (circular) beam spot and target thickness mg/cm2.Zback, Aback, BackThick –Atomic no. and mass no. of the backing material and thickness mg/cm2 of the backing foil.Qvalue, ILPM –Q value MeV for CN formation and inverse level density parameter.AlphaNo, ProtonNo, NeutronNo –Numbers of evaporated alphas, protons and neutrons.Salphac –Alpha separation energies MeV, to be left blank if no alpha evaporation.Sprotonc –Proton separation energies MeV, to be left blank if no proton evaporation.Sneutronc –Neutron separation energies MeV, to be left blank if no neutron evaporation.NEVENT –Number of events i.e. residues to be considered by the program (maximum 5×105). The parameters in input line number 4 are new in this version. If the target is backed by a carbon foil of thickness 125 μg/cm2, the input line would look like “6 12 0.125”. If the target is self-supporting, i.e. there is no backing, value of the last parameter (thickness) should be zero. However, the first two parameters must not be left blank or have 0 values. The input line would look like “6 12 0.0” in this case.3.A new function ThinFoil() has been introduced in the program ters_tra2.c. A thin foil can be inserted anywhere along the path of the residues by calling this function using the following syntax: Status = ThinFoil(argument list); if (Status == 0) continue; The function is particularly useful to place a residue charge-reset foil (usually made of carbon) after the target and is described in Table 1.Table 1Description of the function ThinFoil() used in the program ters_tra2.c. Function name is case sensitive.Name of the functionJob of the functionList of argumentsDescription of argumentsThinFoil()To calculate ion energy loss in a thin foilint arg1, int arg2, int arg3arg1=atomic number of the foil material, arg2=mass number of the foil material, arg3=thickness of the foil mg/cm24.There is a minor change in the input file ters_tra2.inp. Following is the modified list of input parameters in this file with explanation.Z0, A0 –Residue atomic number and mass number.E0, A00, q0 –Energy MeV, mass no. and charge state of the reference particle.NEVENT –Number of events i.e. trajectories to be calculated.5.Program/input files which have been modified in this version are suffixed by “2” in their names (before the extension), e.g., ters_pti.c has been renamed ters_pti2.c. The complete list of files included in the distributed code can be viewed in the readme file.
Restrictions: The present version of the code is applicable to complete fusion reactions only. Calculation of transmission efficiency has been illustrated with a specific recoil separator, viz. the Heavy Ion Reaction Analyzer (HIRA) 4,5, at IUAC. One has to make necessary changes in the code, while performing calculations for other recoil separators. Also, atomic number of the residual nucleus should not exceed 92, as the method used for calculating stopping power of ions 6 is valid for Z⩽92. The code can perform energy loss calculation only in elemental targets and foils (i.e. compounds or alloys are not supported). Further, number of events (NEVENT) in ters_tra2.inp should not exceed the same in ters_pti2.inp.
Running time: From few seconds to several minutes depending on the reaction, number of events and separator layout.
References:1 http://www.astro.caltech.edu/~tjp/pgplot/.2 G.R. Lynch, O.I. Dahl, Nucl. Instr. Methods B 58 (1991) 6.3 L. Meyer, Phys. Status Solidi 44 (1971) 253.4 A.K. Sinha, N. Madhavan, J.J. Das, P. Sugathan, D.O. Kataria, A.P. Patro, G.K. Mehta, Nucl. Instr. Methods A 339 (1994) 543.5 S. Nath, Nucl. Instr. Methods A 576 (2007) 403.6 J.F. Ziegler, J.P. Biersack, U. Littmark, The Stopping and Range of Ions in Solids, vol. I, Pergamon Press, Oxford, 1984.
A time-domain novel beamforming algorithm for ultra-wideband (UWB) microwave imaging is furnished in this paper. A monostatic and bistatic antenna setup is utilized to transmit and receive custom UWB ...pulses. This setup is employed to image various metallic and non-metallic threats attached to a human body. The imaging results demonstrate that the proposed beamforming algorithm allows effective reconstruction of different targets for both monostatic and bistatic cases. An ultra-wideband high gain Antipodal Vivaldi Antenna (AVA) is used as the transducer for the proposed imaging setup. The designed transducer demonstrates measured impedance bandwidth from 660 MHz to 15 GHz (182%) with a peak gain of 15 dBi at 8 GHz. The quality and accuracy of the proposed beamforming algorithm is tested outside the anechoic chamber just to make it more convincing in a real-world dynamic scenario. The result shows that different concealed materials can be detected accurately with the beamforming algorithm. To the best of the authors' knowledge, the proposed algorithm can effectively add up the target responses to obtain a clear and distinct image of the metallic and non-metallic targets.
This work presents a flat‐gain antipodal Vivaldi antenna (AVA) for ultra‐wideband (UWB) microwave imaging applications. The proposed antenna demonstrates measured and simulated impedance bandwidth ...from 2.3 GHz to 20 GHz with a flat gain over the band, with minimum gain variation of 2.9 dBi. The antenna is tested initially for its practical utility by measuring its specific absorption rate (SAR) value. The SAR value is observed in the simulator by modeling a realistic homogeneous as well as a heterogeneous breast phantom. The SAR value obtained complies with both American and European standards when averaged over 1 g as well as 10 g of tissue. The designed antenna is further utilized to detect multiple tumors in a realistic homogeneous and heterogeneous breast phantoms developed in the laboratory environment. The widely popular delay and sum (DAS) algorithm is utilized to reconstruct the tumor images. The imaging is done outside the anechoic chamber with an in‐house monostatic microwave imaging setup just to make it more convincing with real‐world dynamic scenario. The homogeneous phantom with four embedded tumors each of radius 4 mm and the heterogeneous phantom with two tumors, one of radius 3.5 mm and another of radius 5 mm are imaged in this work. The imaging results demonstrate that tumors of different sizes can be detected accurately in the case of both homogeneous and heterogeneous breast phantoms. AVA with an oil paper layer for bandwidth enhancement as well for achieving flat‐gain response is first of its kind to be reported in this work Also, the proposed work utilizes different phantoms for imaging several tumors of differing sizes, which has not before been described.
The letter presents a method of frequency to time domain conversion of Scattering Parameter data for microwave imaging applications. The time to frequency domain conversion was initially tested in ...the MATLAB. The testing was conducted in a realistic microwave imaging environment with an antenna and a heterogeneous breast phantom. Note that, the time domain signal obtained from the Vector Network Analyzer (VNA) as well as the time domain signal obtained with the introduced process is similar indicating efficiency of the proposed method. An ultra‐wideband (UWB) signal is transmitted from the transmitting Antipodal Vivaldi Antenna to the breast phantom and the received signals are collected by the same antenna over a monostatic process. A total of 36 antenna rotations were considered while scanning the phantom from various orientations. All the data stored in the VNA is extracted and the proposed frequency to time domain conversion technique was applied to it. Finally, the Delay and Sum beamforming algoirithm was used to reconstruct the target image.
Tuning surface properties of nanoparticles by introducing charge, surface functionalization, or polymer grafting is central to their stability and applications. Here, we show that introducing ...non-DLVO forces like steric and hydrophobic effects in charged silica nanoparticle suspensions through interaction with a nonionic surfactant brings about interesting modulations in their interparticle interaction and phase behavior. The Ludox TM-40 negatively charged silica suspensions thus exhibit liquid–liquid phase separation driven by the onset of interparticle attraction in the system in the presence of the triblock copolymer Pluronic P123. The observed phase separations are thermoresponsive in nature, as they are associated with lower consolute temperatures and a re-entrant behavior as a function of temperature. The nanoparticle–Pluronic system thus undergoes transformation from one-phase to two-phase and then back to one-phase with monotonic increase in temperature. Evolution of the interparticle interaction in the composite system is investigated by dynamic light scattering (DLS), small angle neutron scattering (SANS), zeta potential, rheological, and fluorescence spectroscopy studies. Zeta potential studies show that the charge interaction in the system is partially mitigated through adsorption of a Pluronic micellar layer on the nanoparticle surfaces. Contrast-matching SANS studies suggest that hydrophobic interactions between the adsorbed micellar layer bring about the onset of interparticle attraction in the system. The results are unique and not reported hitherto in charged silica nanoparticle systems.
Repetitive hot rolling followed by hot pressing or hybrid severe plastic deformation (HSPD) of Mg-4Zn-4Gd was performed at 450 °C to produce ultrafine-grains (UFG) in the alloy. The processed ...specimens are compared with conventional 75% hot rolled, solutionized (ST) and as-cast (AC) specimens to study the mechanical and microstructural evolution. Prior to HSPD process, the pre-processed blocks were solutionized at 400 °C for 24 h to obtain the equiaxed and residual stress free alloy for easy plastic deformation up to the high absolute true strain value of 1.39. The hot rolling (R) and hot pressing (P) methods were combined to deform the material in three different combinations in terms of true strains to achieve the final deformation with true strain 1.39 (75% reduction). The HSPDed specimens were subjected to tensile, hardness and fracture toughness (KQ and JⅠC) tests. The 50R50P specimen has shown better improvement in yield strength (σYS = 268 MPa), tensile strength (σTS = 284 MPa)), and hardness (2.21 GPa) amongst other HSPDed specimen. The improvement in mechanical properties of 50R50P alloy is nearly 9%, 6.5%, and 81%, respectively over the 75% rolled specimen and 154%, 65%, and 176%, respectively against ST specimens. However, the elongation of 50R50P specimen has improved only up to ~ 27% than ST specimen. The highest JⅠC fracture toughness of the processed alloy is ~ 23.25 kJ/m2 when pre-crack is normal to rolling direction (RD) and ~ 18.51 kJ/m2 when pre-crack is parallel to RD analysed in 50R50P and 70R16P specimens, respectively. The strengthening mechanisms operating in the processed alloy is due to solid solution strengthening and deformation slip based failure mechanism in fine grained alloys, which were elucidated with the help of high resolution transmission electron microscopy (HRTEM). The HRTEM results are correlated with X-ray diffraction results of processed alloy. Fracture phenomena for different HSPDed specimens were analysed through FE-SEM to understand the failure characteristics of the alloy under static load.
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