With the emergence of smart and converged home services, the need for the secure and easy interplay of various devices has been increased. Push Button Configuration (PBC) is one of the technologies ...proposed for easy set-up of a secure session between IT and consumer devices. Although the Wi-Fi Direct specification explicitly states that all devices must support the PBC method, its applicability is very limited. This is because the security vulnerability of PBC can be maliciously exploited so that attackers can make illegitimate sessions with consumer devices. To address this problem, this paper proposes a novel Security-enhanced PBC (SePBC) scheme with which we can uncover suspicious or malicious devices. The proposed mechanism has several unique features. First, we develop a secure handshake distance measurement protocol by preventing an adversary sitting outside the region from maliciously manipulating its distance to be fake. Second, it is compatible with the original Wi-Fi PBC without introducing a brand-new methodology. Finally, SePBC uses lightweight operations without CPU-intensive cryptography computation and employs inexpensive H/W. Moreover, it needs to incur little overhead when there is no attack. This paper also designs and implements the proposed SePBC in the real world. Our experimental results and analysis show that the proposed SePBC scheme effectively defeats attacks on PBC while minimizing the modification of the original PBC equipment.
A modeling setup based on the cellular automata (CA) method was developed to model the kinetics of static recrystallization (SRX) in hydroformed steel tubes undergoing the annealing process. In ...addition, the impact of multiaxial deformations on the kinetics of SRX within the hydroformed steel tube was investigated. First, hoop and axial strains developing at the pole of the steel tube during hydroforming were obtained from the digital image correlation measurements. Then, an exact analytical solution was employed to calculate the corresponding hoop and axial stresses at the pole of the bulged tube. Using these biaxial stress–strain curves, the stored energy was calculated for the hydroformed tube specimen. Second, the actual grain topology and crystallographic orientation of grains in the deformed specimen were obtained with the electron backscatter diffraction. Third, the calculated stored energy as well as the microstructural and crystallographic data was incorporated into the CA model as initial conditions to predict the kinetics of SRX in the specimen during annealing. Finally, to assess the accuracy of the CA model, experimental and predicted results were compared in terms of grain topology data including the grain size and aspect ratio distributions, as well as the rate of recrystallization during annealing. A reasonable agreement between the experimental and CA predictions in partial and fully recrystallized specimens was achieved inferring the validity of the developed algorithm and the modeling setup to predict the SRX kinetics during the post-tube hydroforming annealing process.
For 25 Li
2
O–(75 −
x
) B
2
O
3
–
x
Bi
2
O
3
(where
x
= 0, 5, 10, 15, 20, 25, 30, 35, and 40 mol%) glasses, gamma-ray and neutrons attenuation features were explored by theoretical approach using ...ParShield/WinXCOM program, Geant4, and Penelope codes. At
133
Ba (276, 303, 356, and 384 keV),
22
Na (511 and 1280 keV),
137
Cs (662 keV),
54
Mn (835 keV), and
60
Co (1170 and 1330 keV) photon peaks, for all samples, mass attenuation coefficient (
μ
/
ρ
), effective atomic number (
Z
eff
), effective electron density (
N
eff
), half-value layer (HVL), and mean free path (MFP) parameters have been evaluated using ParShield/WinXCOM program. The
μ
/
ρ
values computed by WinXCOM, Geant4, and Penelope codes were compared to check the accuracy, and satisfactory agreement among the values was identified. Moreover, using G
–
P fitting method as a function of penetration depth (1, 5, 10, 15, 20, 25, 30, 35, and 40 mfp) within the photon energy range of 0.015–15 MeV, exposure buildup factor (EBF) and energy absorption buildup factor (EABF) were derived. For all selected glasses, the effectiveness of the neutrons attenuation has been discussed in terms of macroscopic effective removal cross-section (
Σ
R
), coherent scattering cross-section (
σ
cs
), incoherent scattering cross-section (
σ
ics
), absorption cross-section (
σ
A
), and total neutron cross-section (
σ
T
). The ‘
σ
T
’ values have been calculated within 10
−4
–10
−8
MeV neutron energy range using the Geant4 code. The
μ
/
ρ
possessed larger values at the lowest energy and lower values at higher energy regions for all studied glasses. The
μ
/
ρ
,
Z
eff
, HVL, and MFP values showed enhanced γ-ray shielding capability with Bi
2
O
3
content increment in the samples. The 25 Li
2
O–35 B
2
O
3
–40 Bi
2
O
3
(mol%) sample by having larger
Z
eq
and/or
Z
eff
value, faired lower EBF and EABF values. Largest
μ
/
ρ
and
Z
eff
, and minimal HVL, MFP, EBF, and EABF values of 25 Li
2
O–35 B
2
O
3
–40 Bi
2
O
3
(mol%) glass demonstrated its superior γ-ray attenuation ability among all examined glasses. Further, among all glasses, 25 Li
2
O–75 B
2
O
3
(mol%) sample exhibits relatively higher
Σ
R
(0.11326 cm
−1
) and ‘
σ
T
’ (46.109 cm
−1
→ 0.84607 cm
−1
from 1 × 10
−8
MeV → 1×10
−4
MeV neutron energy) values for fast and thermal neutrons attenuation, respectively, indicating its better neutrons absorption competence.
For five B2O3–Bi2O3 glasses, detailedly, γ, neutron, & proton, alpha, and electron (charged particles) shielding efficacies were assessed in this work. The crucial photon attenuating (interaction ...probabilities) parameter i.e., mass attenuation coefficient (μ/ρ) was calculated by Phy-X/PSD software and procured μ/ρ results have been verified through MCNPX, Geant4, & FLUKA codes μ/ρ findings from which a quality unanimity among them was noticed over an energy range of 15 KeV–15 MeV. Following μ/ρ & linear attenuation coefficient (μ) outcomes, Zeff, Neff, HVL, TVL, and MFP have been reckoned and found that all μ/ρ, Zeff, Neff, HVL, TVL, & MFP highly rest on glass chemical contents & photon energy. Zeq and by applying geometric progression (G‒P) fitting parameters (a, b, c, d, & Xk coefficients) EBFs & EABFs were appraised at ten specific penetration depths up to 40 mfp, at energy range of 0.015–15 MeV. The inferred RPE quantities confirmed all chosen glasses quintessential absorption competence for lower energy γ-rays. Utilizing SRIM code the mass stopping powers (MSPs) & projected ranges (PRs) for protons ((ΨP)&(ΦP)) and alpha particles (ΨA)&(ΦA), and with the help of ESTAR database, electron MSP (ΨE) & continuous slowing down approximation (CSDA) ranges for electrons have been approximated at 0.015–15 MeV KE. The fast neutron removal cross-sections (ΣR) were estimated and obtained ΣR was diversified at 0.10978–0.12144 cm−1 range relying on Bi2O3 inclusion in glasses. Based on all acquired outputs, 57.5B2O3-42.5Bi2O3 (mol%) glass possesses superior attenuation capacity for γ-rays and fast neutrons as well as charged particles.
For both the B
O
-Bi
O
-CaO and B
O
-Bi
O
-SrO glass systems,
-ray and neutron attenuation qualities were evaluated. Utilizing the Phy-X/PSD program, within the 0.015-15 MeV energy range, linear ...attenuation coefficients (µ) and mass attenuation coefficients (μ/ρ) were calculated, and the attained μ/ρ quantities match well with respective simulation results computed by MCNPX, Geant4, and Penelope codes. Instead of B
O
/CaO or B
O
/SrO, the Bi
O
addition causes improved
-ray shielding competence, i.e., rise in effective atomic number (
) and a fall in half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP). Exposure buildup factors (EBFs) and energy absorption buildup factors (EABFs) were derived using a geometric progression (G-P) fitting approach at 1-40 mfp penetration depths (PDs), within the 0.015-15 MeV range. Computed radiation protection efficiency (RPE) values confirm their excellent capacity for lower energy photons shielding. Comparably greater density (7.59 g/cm
), larger μ, μ/ρ,
, equivalent atomic number (
), and RPE, with the lowest HVL, TVL, MFP, EBFs, and EABFs derived for 30B
O
-60Bi
O
-10SrO (mol%) glass suggest it as an excellent
-ray attenuator. Additionally, 30B
O
-60Bi
O
-10SrO (mol%) glass holds a commensurably bigger macroscopic removal cross-section for fast neutrons (
) (=0.1199 cm
), obtained by applying Phy-X/PSD for fast neutrons shielding, owing to the presence of larger wt% of 'Bi' (80.6813 wt%) and moderate 'B' (2.0869 wt%) elements in it. 70B
O
-5Bi
O
-25CaO (mol%) sample (B: 17.5887 wt%, Bi: 24.2855 wt%, Ca: 11.6436 wt%, and O: 46.4821 wt%) shows high potentiality for thermal or slow neutrons and intermediate energy neutrons capture or absorption due to comprised high wt% of 'B' element in it.
Determination of mechanical properties in bulged specimens has its own challenges due to their nonhomogeneous geometry. In the present study, a set of empirical hardness-strength-hardening law ...correlations is proposed to estimate the flow behavior of the bulged specimens. To do so, comprehensive empirical strength-hardness correlations applicable for all aluminum alloys were developed by collecting datasets from 16 individual studies. These relationships were then compared with hardness/strength experimental data obtained from heat-treated AA6061 and AA7075 tubular specimens. Then, a set of empirical models was developed to calibrate the coefficients of the Holloman and Voce type hardening laws by utilizing the measured hardness and strength values. Finally, to assure the validity of the proposed model, Rockwell hardness test, conducted on the bulged AA6061 and AA7075, was simulated. To do so, the generated flow behavior of bulged specimens based on hardness measurement was used as input plastic flow data in Abaqus commercial FE software, and the indentation geometry on bulged Al specimens were then compared to the experiments. Comprehensive linear and second-degree polynomial relationships were regressed on compiled data for ultimate tensile and yield strengths, respectively. Reasonable agreement was achieved between hardness-strength relationships obtained for all Al alloys and processed AA6061 and AA7075 tubular samples, confirming that these relationships are applicable for any Al alloys regardless of product type and process design. Finally, although both Holloman and Voce type hardening laws gave reasonable estimation of flow behavior in Al tubular specimens particularly at high strain values, Voce model provided a better estimation in comparison to Holloman hardening law. The FE analysis of Rockwell hardness test confirmed that the proposed hardness-strength-hardening law relationship based on Voce type hardening rule was sufficiently accurate in predicting the flow curve in bulged 6061 and 7075 Al alloys.
Graphene is one of the most favorite materials for materials science research owing to its distinctive chemical and physical properties, such as superior conductivity, extremely larger specific ...surface area, and good mechanical/chemical stability with the flexible monolayer structure. Graphene is considered as a supreme matrix and electron arbitrator of semiconductor nanoparticles for environmental pollution remediation. The present review looks at the recent progress on the graphene-based metal oxide and ternary composites for photocatalysis application, especially for the application of the environmental remediation. The challenges and perspectives of emerging graphene-based metal oxide nanocomposites for photocatalysis are also discussed.
In indoor localization, it is crucial to guarantee a high level of accuracy for various location-based services. An ultrasonic technique is one of the best candidates to meet this need because it is ...capable of performing precise distance measurements as well as enabling nonintrusive localization that requires no receiver to be carried. Nevertheless, its applicability is severely limited by the fact that ultrasonic waves are likely to collide with one another if a multiple access scheme is not equipped, as is usually the case for low-cost ultrasonic sensors. Also, environmental changes such as addition/removal of obstacles or dislocation of sensors themselves may further degrade the localization performance. To remedy these problems, we take a genetic approach to avoid collisions of ultrasonic waves, thereby maximizing the localization accuracy. Specifically, we propose a self-configurable, device-free, and low-cost ultrasonic sensor grouping technique for indoor localization that precisely quantifies the degree of collisions by using kernel distance and forms an optimal number of sensing groups to maximize the spatial reuse as well as to detect environmental changes in real time. Our comprehensive evaluation results on a real testbed demonstrate that it achieves very small localization errors of 20.6-32.6 cm, which is comparable with the size of target, i.e., human body, and detects any environmental change in 5.2-7 s followed by reconfiguring the sensing groups in 10.1-18.4 s.
Supplementary cementitious materials (SCMs) and chemical additives (CA) are incorporated to modify the properties of concrete. In this paper, SCMs such as fly ash (FA), ground granulated blast ...furnace slag (GGBS), silica fume (SF), rice husk ash (RHA), sugarcane bagasse ash (SBA), and tire-derived fuel ash (TDFA) admixed concretes are reviewed. FA (25-30%), GGBS (50-55%), RHA (15-20%), and SBA (15%) are safely used to replace Portland cement. FA requires activation, while GGBS has undergone in situ activation, with other alkalis present in it. The reactive silica in RHA and SBA readily reacts with free Ca(OH)
in cement matrix, which produces the secondary C-S-H gel and gives strength to the concrete. SF addition involves both physical contribution and chemical action in concrete. TDFA contains 25-30% SiO
and 30-35% CaO, and is considered a suitable secondary pozzolanic material. In this review, special emphasis is given to the various chemical additives and their role in protecting rebar from corrosion. Specialized concrete for novel applications, namely self-curing, self-healing, superhydrophobic, electromagnetic (EM) wave shielding and self-temperature adjusting concretes, are also discussed.
An environmentally techno, reasonably viable waste utilization is vital for the sustainability of human civilization. In view of that, orange peel (OP) has been considered for this study to utilize ...as organic waste materials for thermal energy storage application. OP has been pyrolyzed into porous biochar and has been used for the shape stabilization of myristic acid (MA) as phase change materials (PCMs). MA has been loaded in different content inside orange peel biochar and thermal stability and performance of the synthesized PCMs (MAOP samples) have been studied for their suitable applications. Biochar to MA ratio at 1:4 has been found to be optimum for the maximum accommodation of the MA in biochar pores. The highest encapsulation ratio and efficiency have been found 39.60% and 39.13%, respectively whereas the maximum heat storage capability has been found to be 67.2 J/g. Excellent performance against leakage during phase transition and congruent thermal cycle stability have been manifested by all MAOP samples. The superior properties demonstrated by the MAOP samples are attributed to the capillary action, strong surface tension, and space confinement effects offered by the porous structures and the surface functionalities of the biochar.
•Porous biochar has been synthesized from waste orange peels (OP) by pyrolysis.•PCM composites are made by impregnating myristic acid into porous OP biochar.•Highest encapsulation ratio and efficiency are found 39.60% and 39.13%.•Congruent phase change reversibility is found for all biochar/fatty acid composites.•The composite PCMs show leakage free performances during phase transitions.
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