416 research outputs found
Secure Hop-by-Hop Aggregation of End-to-End Concealed Data in Wireless Sensor Networks
In-network data aggregation is an essential technique in mission critical
wireless sensor networks (WSNs) for achieving effective transmission and hence
better power conservation. Common security protocols for aggregated WSNs are
either hop-by-hop or end-to-end, each of which has its own encryption schemes
considering different security primitives. End-to-end encrypted data
aggregation protocols introduce maximum data secrecy with in-efficient data
aggregation and more vulnerability to active attacks, while hop-by-hop data
aggregation protocols introduce maximum data integrity with efficient data
aggregation and more vulnerability to passive attacks.
In this paper, we propose a secure aggregation protocol for aggregated WSNs
deployed in hostile environments in which dual attack modes are present. Our
proposed protocol is a blend of flexible data aggregation as in hop-by-hop
protocols and optimal data confidentiality as in end-to-end protocols. Our
protocol introduces an efficient O(1) heuristic for checking data integrity
along with cost-effective heuristic-based divide and conquer attestation
process which is in average -O(n) in the worst scenario- for
further verification of aggregated results
Solvation Free Energies of K+, Rh+ and Cs+ Ions in Methanol-N,N-dimethylformamide Mixtures
The selective solvation of K+,Rb+and Cs+ ions has been studied
at 25 DCby solubility measurements. The solubility of tetraphenylboride
salts, KBPh4, RbBPh4 and CsBPh4 increases with the
addition of N,N-dimethylformamide (DMF) to methanol (CH30H)
solutions. From the solubility data, the solvation free energies
of the ions under consideration are evaluated on applying the
asymmetric tetraphenylarsonium-tetraphenylboride (ΔG° Ph4As+>
>ΔG° Ph4B-) assumption and their values are discussed
Surface investigation of chitosan film with fatty acid monolayers
The surface pressure- molecular area (ï°-A) isotherm curves of two fatty acids of different chain lengths, i.e. stearic (C18) and arachidic (C20) acids, were obtained by using Langmuir-Blodgett (LB) technique. Results showed clear isotherm plots with limiting mean molecular area around 21 Ă
2 for both acids. However, the monolayer was found to collapse at higher than 33 mN m-1 and 21 mN m-1 for stearic acid and arachidic acid respectively. The effect of Langmuir-Blodgett monolayers of the acids was investigated by atomic force microscopy (AFM). Chitosan film, before and after dipping in water, was also studied by means of AFM so that it could be used for comparison. It was found that the surface of chitosan was more homogeneous and smoother after dipping in water. In addition, more homogeneous surfaces were achieved after transferring a layer of the fatty acid onto the substrate
Electron impact excitation-ionization of molecules
In the last few decades, the study of atomic collisions by electron-impact has made significant advances. The most difficult case to study is electron impact ionization of molecules for which many approximations have to be made and the validity of these approximations can only be checked by comparing with experiment.
In this thesis, I have examined the Molecular three-body distorted wave (M3DW) or Molecular four-body distorted wave (M4DW) approximations for electron-impact ionization. These models use a fully quantum mechanical approach where all particles are treated quantum mechanically and the post collision interaction (PCI) is treated to all orders of perturbation. These electron impact ionization collisions play central roles in the physics and chemistry of upper atmosphere, biofuel, the operation of discharges and lasers, radiation induced damage in biological material like damage to DNA by secondary electrons, and plasma etching processes.
For the M3DW model, I will present results for electron impact single ionization of small molecules such as Water, Ethane, and Carbon Dioxide and the much larger molecules Tetrahydrofuran, phenol, furfural, 1-4 Benzoquinone. I will also present results for the four-body problem in which there are two target electrons involved in the collision. M4DW results will be presented for dissociative excitation-ionization of orientated D2. I will show that M4DW calculations using a variational wave function for the ground state that included s- and p- orbital states give better agreement to the experimental measurements than a ground state approximated as a product of two 1s-type Dyson orbitals --Abstract, page iv
The preparation and characterization of chitosan/poly (vinyl alcohol) blended films : mechanical, thermal and surface investigations
In this study, blends of chitosan (CS) and polyvinyl alcohol (PVA) (CS/PVA) having various proportions were prepared and characterized by universal mechanical tester, the differential scanning calorimetry (DSC) and contact angle measurements. Studying the mechanical properties of the films showed that blending improved the tensile strength, which increased with increasing PVA content up to 40% while the elongation% at break of the blends was decreased compared to that of the pure components. The obtained results of DSC suggested that some interaction between chitosan and PVA mostly took place. Static water contact angle measurements showed an improvement in the wettability of the obtained films
Taxonomic revision of the genus Scorpiurus L. (Fabaceae)
The morphological and anatomical characteristics of different parts were utilized to reassess the taxonomic status in Scorpiurus L. species naturally growing in Egypt. There were significant differences among the studied species of plants and hence the results clearly showed two distinct species. Based on the studied morphological and anatomical differences S. muricatus L. is differentiated into three different varieties. These are muricatus L., laevigatus (Sibth. & Sm.) Boiss. and subvillosus (L.) Fiori. An artificial key to both species and varieties are provided
Solar Pond Driven Air Conditioning Using Seawater Bitterns and MgCl<sub>2</sub> as the Desiccant Source
Solar energy is used for a wide range of applications such as electricity production, desalination, cooling, heating, etc. Solar-based technologies are widely spread and increasingly studied in the industry. This theoretical and experimental study focuses on solar ponds as a desiccant and low-grade energy source. A thermal model has been developed for a salinity gradient solar pond (SGSP) with a non-convective zone split into 10 sub-zones. A solar pond was constructed and used as a case study for the validation of the predictive model capabilities. The dimensional characteristics of the pond, as well as the solar radiation intensity and ambient temperature data obtained from the meteorological data, were used to produce the solar pondâs zone thermal behaviour data. With regards to the thermal behaviour measurements obtained from the solar pond, the predicted data were found to be higher. There is a significant difference between the real-world and meteorological data obtained, the difference between the predicted and real-world pond temperature data was also attributed to the fact that the actual absorbed solar radiation was reduced due to wall shading effect, turbidity and insufficient duration of operation of the pond. In the following year, the stored heat from the previous summer would be expected to improve thermal storage values obtained partially
Physical layer authenticated image encryption for Iot network based on biometric chaotic signature for MPFrFT OFDM system
In this paper, a new physical layer authenticated encryption (PLAE) scheme based on the multi-parameter fractional Fourier transformâOrthogonal frequency division multiplexing (MP-FrFT-OFDM) is suggested for secure image transmission over the IoT network. In addition, a new robust multi-cascaded chaotic modular fractional sine map (MCC-MF sine map) is designed and analyzed. Also, a new dynamic chaotic biometric signature (DCBS) generator based on combining the biometric signature and the proposed MCC-MF sine map random chaotic sequence output is also designed. The final output of the proposed DCBS generator is used as a dynamic secret key for the MPFrFT OFDM system in which the encryption process is applied in the frequency domain. The proposed DCBS secret key generator generates a very large key space of (Formula presented.). The proposed DCBS secret keys generator can achieve the confidentiality and authentication properties. Statistical analysis, differential analysis and a key sensitivity test are performed to estimate the security strengths of the proposed DCBS-MP-FrFT-OFDM cryptosystem over the IoT network. The experimental results show that the proposed DCBS-MP-FrFT-OFDM cryptosystem is robust against common signal processing attacks and provides a high security level for image encryption application. © 2023 by the authors
Solvation Free Energies of K+, Rh+ and Cs+ Ions in Methanol-N,N-dimethylformamide Mixtures
The selective solvation of K+,Rb+and Cs+ ions has been studied
at 25 DCby solubility measurements. The solubility of tetraphenylboride
salts, KBPh4, RbBPh4 and CsBPh4 increases with the
addition of N,N-dimethylformamide (DMF) to methanol (CH30H)
solutions. From the solubility data, the solvation free energies
of the ions under consideration are evaluated on applying the
asymmetric tetraphenylarsonium-tetraphenylboride (ΔG° Ph4As+>
>ΔG° Ph4B-) assumption and their values are discussed
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