An iterative learning approach for network contraction: Path finding problem in stochastic time‐varying networks

Path finding problem has a broad application in different fields of engineering. Travel time uncertainty is a critical factor affecting this problem and the route choice of transportation users. The major downside of the existing algorithms for the reliable path finding problem is their inefficiency in computational time. This study aims to develop a network contraction approach to reduce the network size of each specific origin and destination (OD) pair in stochastic time‐dependent networks. The network contraction is based on the comparison of optimistic and pessimistic solutions resulting from minimum and maximum travel time realizations of a Monte‐Carlo simulation (MCS)‐based approach. In this respect, the researchers propose a learning approach to utilize the information of the realizations in the initial iterations of the MCS approach. Implementation of this approach is in place for several OD pairs of two real‐world large‐scale applications. First, it is calibrated for the Chicago downtown network; the performance and accuracy of the proposed approach are investigated by comparing the results against that of the approach without any network contraction. In addition, the Salt Lake City network illustrates the transferability of the approach to other networks. The results demonstrate significant computational improvements, with an acceptable accuracy level relative to the approach without network contraction.     

Evaluation of the Optical and Structural Properties of Constructed Bis-indole Derivatives Using (Sm2O3/SiO2) Catalyst

Silicon - (SiO2/Sm2O3) was successfully synthesized and examined using scanning electron microscopy; X-ray diffraction and Fourier transform infrared spectroscopy. Obtained data shows the formation...     

Characterization of Invert Soda Lime Silica Glasses Containing High Titania Content Together with their Glass Ceramics

Silicon - Collective structural, optical and thermal properties were investigated for some prepared soda lime silicate glasses containing high TiO2 contents (35, 40, 45%). X-ray diffraction and...     

Gamma rays interactions with WO3-doped lead borate glasses

Optical and FT infrared spectral properties of tungsten ions in a host lead borate glass with composition PbO 55%, B₂O₃ 45% (wt%) were studied. The same spectral properties were re-measured after subjecting the samples to successive gamma irradiation. The work was undertaken to justify the state of tungsten ions in such glass system by combined spectral investigations. Optical and FTIR spectral studies were confirmed by investigating electron spin resonance (ESR) of the undoped and WO₃-doped samples before and after gamma irradiation. The optical spectrum of the undoped glass exhibits strong and wide UV absorption bands, which are related to the combined UV spectra of trace iron impurities (Fe³⁺ ions) and that from divalent lead (Pb²⁺) ions. Optical studies of WO₃-doped sample indicate the presence of tungsten ions mostly in the hexavalent W⁶⁺ state. The presence of tungsten ions as structural groups was obtained by comparing the FTIR spectra of the undoped and WO₃-doped samples. ESR spectra confirm the optical and FTIR spectral studies. The studied host lead borate glass has been found to show obvious shielding behavior towards successive gamma irradiation as revealed by the constancy of optical absorption spectral curves.     

Modeling Framework and Decomposition Scheme for On‐Demand Mobility Services with Ridesharing and Transfer

This article presents a modeling framework for the operations of on‐demand mobility services (ODMS) in urban areas. The framework provides the capabilities to analyze ODMS operations while representing emerging services such as ridesharing and transfer. The problem is formulated as a mixed integer program and an efficient decomposition‐based methodology is developed for its solution. The methodology adopts a modified version of the column generation algorithm, which implements iterative decomposition and network augmentation techniques to allow studying networks of moderate size. The results of a set of experiments considering grid and real‐world networks are presented. The results show that increasing the number of passengers willing to rideshare and/or transfer improves the overall performance of ODMS as it increases number of served passengers and associated profit and reduces the number of used vehicles. Although presented as an offline planning tool, the methodology could be adopted for real‐time applications as adequate computational resources become available.     

The Elusory Role of Low Level Doping Transition Metals in Lead Silicate Glasses

A deconvolution method based iterative system was employed for the analysis of Infrared (IR) absorption spectra of some prepared lead silicate unfilled glasses together with samples filled with a low doping level of one of the first 3d-transition metal oxides (TMO’s) (TiO₂→CuO) in the region of 4,000-400 cm^-1. The IR spectra were analyzed to determine, evaluate, differentiate the various vibrational modes and to retrace precisely the role of low level doping of the different TMO’s in the structural changes. The first examination reveals a close similarity between the different transition metals doped samples, but careful inspection indicates there are some minor differences depending on the type of TM ions. These observed data are correlated with the similarity of the 3d orbitals in the neutral atoms and when the atoms are ionized. It was also observed that the 3d orbitals become more stable than the 4s orbitals.     

Structure and properties of CaF<Subscript>2</Subscript>–B<Subscript>2</Subscript>O<Subscript>3</Subscript> glasses

FTIR spectroscopy has been employed to investigate the structure of CaF₂–B₂O₃ glasses. It is proposed that CaF₂ partially modifies the borate network forming \textCa _{1 / 2} ²⁺ [\textBO _{3 / 2} \textF] ^- {\text{Ca}}_{ 1 / 2}^{ 2+ } [{\text{BO}}_{ 3 / 2} {\text{F]}}^{ - } units. The rest of CaF₂ is assumed to build an amorphous network formed of CaF₄ tetrahedra. Analysis of density and molar volume revealed that the volume of CaF₄ tetrahedron in the studied glasses is slightly greater than that in the crystalline form. Data of density, molar volume, and electric conductivity have been correlated with the glass structure. As far as the authors know, CaF₂–B₂O₃ glasses are investigated for the first time.     

Structural,optical, and dielectric characteristics of copper oxide nanoparticles loaded CMC/PEO matrix

Journal of Materials Science - Polymer nanocomposite films were prepared using the casting method through filling a polymer mixture of carboxymethyl cellulose (CMC) and polyethylene oxide (PEO)...