A self learned invasive weed-mixed biogeography based optimization algorithm for RFID network planning

The optimal placement of the RFID readers inaugurates an ongoing research field, namely the RFID network planning (RNP). The main issue in the RNP is to know how many readers have to be used and what is their best distribution that guarantees fulfillment of multiple objectives. The common RNP objectives are the optimal coverage, readers’ interference avoidance, redundant reader elimination, load balance among deployed readers and minimum power losses, which are considered as conflicting objectives that leads the RNP to be an NP-hard problem need to be solved. The contributions in this paper are: firstly, utilizing both the Biogeography based optimization (BBO) and the Hybrid Invasive Weed-Biogeography based optimization (HIW-BBO) as new algorithms have not used before for solving the RNP. Secondly, we proposed a Self Learning (SL) strategy with a mixed BBO Migration (MBBOM) operation to modify the HIW-BBO algorithm in an algorithm called Self Learned Invasive Weed-Mixed Biogeography based optimization (SLIWMBBO). Thirdly, the performance of the proposed SLIWMBBO algorithm is compared to both the HIW-BBO and the Self Adaptive Cuckoo Search (SACS) optimization algorithms according to a set of 13 benchmark functions. The results of this comparison encourage the application of the SLIWMBBO as an optimization algorithm for solving the complex problems. Lastly, the BBO, HIW-BBO and SLIWMBBO optimization algorithms are used for solving three complex RNP instances and compared to the SACS algorithm. Simulation results of the SLIWMBBO are outstanding and demonstrate its superiority over the compared algorithms.

     

Flexural response analysis of passive and active near-surface-mounted joints: experimental and finite element analysis

The near surface mounted system is considered an innovative strengthening technique used to increase the flexural and shear capacity of RC structures. Although, many researches have been carried out to study the flexural response of NSM joints, further research is still required to cover all the controlling parameters. In this research, the effects of the FRP cross sectional area, end anchoring, and partial bonding of the NSM bars were experimentally investigated. A numerical investigation utilizes the non-linear finite element (FE) modeling was also performed using ANSYS^®. Progressive continuum damage mechanics along with the fracture concepts were employed to simulate the damage initiation and propagation at the epoxy-concrete interface. The developed FE models were calibrated and verified using the obtained experimental results. Based on the good agreement obtained between experimental and FE results, the numerical analysis was extended to conduct an extensive parametric investigation. The numerically investigated parameters included the NSM bar length, tensile steel corrosion, concrete compressive strength, Activating/prestressing the NSM reinforcement, and axial stiffness of the prestressed NSM joints.     

Sucralose as co-crystal co-former for hydrochlorothiazide: development of oral disintegrating tablets

Development of oral disintegrating tablets requires enhancement of drug dissolution and selection of sweetener. Co-crystallization of drugs with inert co-former is an emerging technique for enhancing dissolution rate. The benefit of this technique will become even greater if one of the sweeteners can act as co-crystal co-former to enhance dissolution and mask the taste. Accordingly, the objective of this work was to investigate the efficacy of sucralose as a potential co-crystal co-former for enhancing the dissolution rate of hydrochlorothiazide. This was extended to prepare oral disintegrating tablets. Co-crystallization was achieved after dissolving hydrochlorothiazide with increasing molar ratios of sucralose in the least amount of acetone. The co-crystallization products were characterized using Fourier transform infrared spectroscopy, differential thermal analysis and powder X-ray diffraction. These measurements indicated that co-crystallization process started at a drug sucralose molar ratio of 1:1 and completed at 1:2. The developed co-crystals exhibited faster drug dissolution compared with the control, with co-crystal containing the drug with sucralose at 1:2 molar ratio being optimum. The later was used to prepare fast disintegrating tablets. These tablets had acceptable physical characteristics and showed fast disintegration with subsequent rapid dissolution. The study introduced sucralose as co-crystal co-former for enhanced dissolution and masking the taste.     

Comparative Study of the Layered Perovskites Pr1−xA1+xCoO4, (A = Sr,Ca)

We present structural, magnetic, and electric properties of Pr_1?xCa_1+xCoO₄ layered perovskites and compare them with the results of recently studied Pr_1?xSr_1+xCoO₄. The Rietveld refinements of X‐ray powder diffraction (XRD) patterns indicate that all samples crystallize in the K₂NiF₄‐type structure with space group symmetry I4/mmm. The parent compounds Pr(Ca, Sr)CoO₄ are paramagnetic insulators. Upon increasing x, a variety of different magnetic transitions can be identified. The complex magnetic behavior results from the interplay of competing interactions. The temperature‐dependent electrical resistivity of the samples shows 2D variable range hopping (2D‐VRH). The results are discussed with respect to structure?property relationships.     

Metallic and Superconducting Photonic Crystal

We have investigated the transmittance for two kinds of photonic crystals; (i) One-dimensional metallic photonic crystals (1DMPCs) and (ii) One-dimensional superconducting photonic crystals (1DScPCs). The variance of the intensity and the bandwidth of the transmittance are strongly dependent on the thicknesses and frequencies. We have compared the transmittance spectra in 1DScPCs and 1DMPCs at low frequencies, and we present some details about the transmittance spectra by using Transfer Matrix Method (TMM) at the same conditions.      

Enhancement-mode high electron mobility transistors (E-HEMTs)lattice-matched to InP

The fabrication and characterization of high-speed enhancement-mode InAlAs/InGaAs/InP high electron mobility transistors (E-HEMTs) have been performed. The E-HEMT devices were made using a buried-Pt gate technology. Following a Pt/Ti/Pt/Au gate metal deposition, the devices were annealed in a nitrogen ambient, causing the bottom Pt layer to sink toward the channel. This penetration results in a positive shift in threshold voltage. The dc and RF performance of the devices has been investigated before and after the gate annealing process. In addition, the effect of the Pt penetration was investigated by fabricating two sets of devices, one with 25 nm of Pt as the bottom layer and the other with a 5.0 nm bottom Pt layer. E-HEMTs were fabricated with gate lengths ranging from 0.3 to 1.0 μm. A maximum extrinsic transconductance (g_mext) of 701 mS/mm and a threshold voltage (V_T) of 167 mV was measured for 0.3 μm gate length E-HEMTs. In addition, these same devices demonstrated excellent subthreshold characteristics as well as large off-state breakdown voltages of 12.5 V. A unity current-gain cutoff frequency (f _t) of 116 GHz was measured as well as a maximum frequency of oscillation (f_max) of 229 GHz for 0.3 μm gate-length E-HEMTs     

Making bricks from rice-hull ash

The fuel ash from rice mills has been used for making building-quality bricks when fully decarbonised, but this is not a simple process. The National Research Centre at Dokki, Cairo, has used the partially decarbonised ash with magnesium oxychloride cement to make light-weight bricks with crushing strengths up to 30 kg/cm².     

Optical Properties of New Type of Superconductor-Semiconductor Metamaterial Photonic Crystals

Based on the fundamentals of the characteristic matrix method, we theoretically investigate the optical properties of onedimensional superconductor metamaterial photonic crystals. The photonic crystals are composed of a superconductor layer and two semiconductor metamaterial layers of In_0.53Ga_0.47As with different doping densities. The numerical results show negative values in permittivity of the metamaterial layer along a broad band of the incident radiation. The negative values show a significant effect on the optical properties of the present structure. Moreover, the optical properties of our design can be controlled by different parameters such as thicknesses of the layers, the operating temperature and the doping density. Our results may be suitable for different applications in the optical community.     

Fano Resonance by Means of the One-Dimensional Superconductor Photonic Crystals

In the present work, we introduce a study about the reflectance properties of a one-dimensional superconductor photonic crystal in a different manner. Our structure is designed from alternately layers of high-temperature superconducting material (BSCCO) and a conventional superconducting material (Nb) terminated by the dielectric cap layer. The investigated numerical results are essentially based on the basics of the transfer matrix method and the two-fluid model. The numerical results showed the appearance of two sharp peaks, which are referred to Fano and electromagnetic-induced reflectance resonances. Also, we demonstrate the effects of many parameters on the reflectance properties of Fano resonance and the electromagnetic-induced reflectance. The effects of the constituent layer thicknesses, the number of periods, the operating temperature, the angle of incidence, and the refractive index of the dielectric cap layer are all considered. Finally, the effects of hydrostatic pressure on the Fano and EIR resonances are studied and calculated. This structure can play an important role in optical switching devices.     

Evolution of Phononic Band Gaps in One-Dimensional Phononic Crystals that Incorporate High-<Emphasis Type="Italic">T</Emphasis><Subscript>c</Subscript> Superconductor and Magnetostrictive Materials

In this work, we calculate the reflectance of one-dimensional phononic crystals (1D PnCs) using the transfer matrix method. We present numerical results for two different PnC structures, the first one, PnCs1, contains high- T _c superconducting compound (Bi-2223) and the second, PnCs2, contains a giant magnetostrictive material (Terfenol-D). Magnetostriction is a property of ferromagnetic materials that causes them to change their shape/dimensions when subjected to external magnetic field. PnC studies that dealt with such materials are few. In this study, we focus on discussing the effects of the temperature and the magnetic field on the phononic gaps of these PnCs. For PnCs1, numerical results show that local resonant modes of elastic waves with brilliant sharpness can be realized. In addition, increasing the temperature leads to a decrease in the gap width which can be controlled by the magnetic field due to the effect of the magnetic field on the velocity of waves in the high- T _c superconducting compound, the magnetic field effectively can widen the gap. For PnCs2, numerical results show that the gap width increases by increasing the magnetic field because the magnetostrictive material directly expanded in the presence of the magnetic field.