A hybrid model of fuzzy goal programming and grey numbers in continuous project time,cost, and quality tradeoff

The purpose of this paper is to develop current mathematical models of cost, time, and quality tradeoffs in conditions that parameters of project activities are estimated uncertainly by grey numbers. In some projects like construction projects, activities can be done within a much shorter time by increasing in the resources, while project's cost may rise at the same time. In such situations, managers are usually required to determine the best combination of cost, time, and quality parameters of the activities, although their information regarding these parameters is limited and rather incomplete. The greyness of these parameters in the proposed method can aid managers to deal with these conditions. The most important aspect of the proposed model is that it considers uncertainty of the project planning data in the form of grey numbers. A combination of fuzzy goal programming and grey linear programming is also developed to solve the proposed model. Finally, this model will provide the managers with a stronger ability to face with uncertainty in project management and planning. The application of this model is examined in a numerical example. As its major finding, the model determines an optimal range in which the project managers can respond to intrinsic changes that may occur in the parameters during a project.     

Photo-electrochemistry of metallic titanium/mixed phase titanium oxide

In this study, the effect of potassium hydroxide concentration in anodization bath, anodization time, and calcination temperature on the photo-electrochemical behavior of metallic titanium/mixed phase titanium oxide is investigated. Further, the phase structure of a titanium oxide photocatalyst prepared on a titanium electrode through a high-voltage anodization method is examined. The study exploits photo-electrochemical, Fourier transform infrared spectroscopy attenuated total reflectance (FTIR–ATR), X-ray diffraction, and Raman spectroscopic methods to obtain better insights into the mechanism of mixed-phase titanium oxide formation. In this regard, the photo-electrochemical properties of the photocatalysts prepared in single excitation energy, violet light (410 nm), were investigated. The anodization time and the potassium hydroxide concentration in the anodization bath have significant effects on the photo-electrochemical properties of the photocatalysts. The experiments show that the effect of potassium hydroxide concentration is a function of the anodization potential applied, demonstrating different patterns as the anodization potential changes. Furthermore, FTIR-ATR, X-ray diffraction, and Raman spectroscopic studies reveal that the extended anodization times decrease the population of OH-containing groups, leading to lower photo-electrochemical performance. On the other hand, the formation of anatase phases becomes more favorable only in the extended anodization times before application of the calcination process. Additionally, the calcination temperature has a significant impact on the anatase to rutile ratio. Finally, increasing potassium hydroxide concentration leads to the formation of an amorphous titanium oxide layer. It can be concluded that the obtained information might have a significant impact on the preparation of titanium oxide and other metal oxide photocatalysts through the high voltage anodization process.     

Semantic Interoperability of Heterogeneous Semantic Resources

This paper presents a three-step approach to enhance interoperability between heterogeneous se- mantic resources. Firstly, we construct homogeneous representations of these resources in a pivot format, namely OWL DL, with respect to the semantics expressed by the original representation languages. Secondly, mappings are established between concepts of these standardised resources and stored in a so-called articulation ontology. Thirdly, an approach for ranking those mappings is suggested in order to best fit users' needs. This approach is currently being implemented in the Semantic Resources “Interoperabilisation” and Linking System (SRILS). The mapping results as well as the work to be done are discussed.     

A multiple multilayer perceptron neural network with an adaptive learning algorithm for thyroid disease diagnosis in the internet of medical things

The Journal of Supercomputing - Medical information systems such as Internet of Medical Things (IoMT) are gained special attention over recent years. X-ray and MRI images are important sources of...     

Evaluating the Optical Properties of TiO2 Nanofluid for a Direct Absorption Solar Collector

Recent studies specify that designated nanofluids may increase the proficiency of direct absorption solar thermal collectors. To determine the efficiency of nanofluids in solar applications, their capability to change light energy to thermal energy must be identified (i.e., the absorption spectrum of the solar material). In view of that, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (200– 1100 nm). In the first decade of nanofluid research, most of the focus was on measuring and modeling the fundamental thermophysical properties of nanofluids (i.e., thermal conductivity, density, viscosity, and convection coefficients). Lately, considerable focus is given to the fundamental optical properties of nanofluids. However, the effect of particle size, shape, and volume fraction of nanoparticles as well as alternation of the base fluids, which can significantly affect scattering and absorption, have not been addressed to date in the literature. In this study, the effects of size and concentration of TiO₂ nanoparticles on the extinction coefficient were analyzed using the Rayleigh approach. The results show that smaller particle size (<20 nm) has a nominal effect on the optical properties of nanofluids. Volume fraction is linearly proportionate to the extinction coefficient. Considering a nanoparticle size of 20 nm, almost 0% transmissivity is obtained for wavelengths ranging from 200 to 300 nm. However, a sudden increase of 71% in transmissivity is noted from 400 nm, gradually increasing to 88% and becoming similar to that of water at 900 nm. Promising results are observed for volume fractions below 0.1%.     

Airborne hyperspectral discrimination of tree species with different ages using discrete wavelet transform

In this article, the capability of discrete wavelet transform (DWT) to discriminate tree species with different ages using airborne hyperspectral remote sensing is investigated. The performance of DWT is compared against commonly used traditional methods, i.e. original reflectance and first and second derivatives. The hyperspectral data are obtained from Thetford forest of the UK, which contains Corsican and Scots pines with different ages and broadleaved tree species. The discrimination is performed by employing three different spectral measurement techniques (SMTs) including Spectral Angle Mapper (SAM), Spectral Information Divergence (SID), and a combination of SAM and SID. Five different mother wavelets with a total of 50 different orders are tested. The wavelet detail coefficient (CD) from each decomposition level and combination of all CDs plus the approximation coefficient from the final decomposition level (C-All) are extracted from each mother wavelet. The results show the superiority of DWT against the reflectance and derivatives for all the three SMTs. In DWT, C-All provided the highest discrimination accuracy compared to other coefficients. An overall accuracy difference of about 20–30% is observed between the finest coefficient and C-All. Amongst the SMTs, SID provided the highest accuracy, while SAM showed the lowest accuracy. Using DWT in combination with SID, an overall accuracy up to around 71.4% is obtained, which is around 13.5%, 14.7%, and 27% higher than the accuracies achieved with reflectance and first and second derivatives, respectively.     

Frequency modulation response due to the intensity modulation of fiber-grating Fabry–Perot lasers

A comprehensive study on the small-signal frequency modulation (FM) characteristics of a fiber-grating Fabry–Perot (FGFP) laser is numerically conducted. Fiber Bragg grating (FBG) is used as a wavelength selective element to control the properties of the laser output by controlling the external optical feedback (OFB) level. In addition to the external OFB level, the effect of other parameters such as temperature, injection current, cavity volume, nonlinear gain compression factor, linewidth enhancement factor, and fiber-grating (FG) parameters on FM characteristics of the laser are investigated. The study is performed by modifying a set of rate equations that are solved by considering the effects of external OFB and ambient temperature (T) variations. The temperature dependence (TD) of FM characteristics is calculated according to TD of laser parameters instead of using well-known Pankove relationship. Results show that the optimum external fiber length (L_ext) is 3.1?cm and the optimum range of working temperature for FGFP laser is within?±?2?°C from the FBG reference temperature (T_o). Also, it is shown that antireflection (AR) coating reflectivity and the linewidth enhancement factor have no significant effect on the FM response. The FM spectra peak amplitude is less than 5?dB with 5?mW output power. Good temperature stability is also obtained.     

Layer-by-Layer Electrochemical Assembly of Pt/Phosphomolybdic Acid/Poly(diphenylamine)/PGE for Electrocatalytic Oxidation of Methanol

Journal of Electronic Materials - In this work, a layer-by-layer (LbL) electrochemical assembly was fabricated comprising alternating layers of poly(diphenylamine) (PDPA), phosphomolybdic acid...     

70-Gb/s amplitude-shift-keyed system with 10-GHz clock recovery circuit using duty cycle division multiplexing

The performance of ASK over DCDM for up to seven channels is reported. The aggregate bit rate of 70 Gb/s is achieved with only 160-GHz modulation bandwidth. The clock and data recovery are realized at 10-GHz clock rate, which is very economic and efficient. At 7 × 10 Gb/s, the worst receiver sensitivity of −10 dBm, OSNR of 41.5 dB and chromatic dispersion tolerance of ±7 ps/nm are achieved. Whereas, for the best channel, the receiver sensitivity, OSNR, and chromatic dispersion tolerance are −23.5 dBm, 29 dB, and ±36 ps/nm, respectively.