Predicting roadheader performance by using artificial neural network

With growing use of roadheaders in the world and its significant role in the successful accomplishment of a tunneling project, it is a necessity to accurately predict performance of this machine in different ground conditions. On the other hand, the existence of some shortcomings in the prediction models has made it necessary to perform more research on the development of the new models. This paper makes an attempt to model the rate of roadheader performance based on the geotechnical and geological site conditions. For achieving the aim, an artificial neural network (ANN), a powerful tool for modeling and recognizing the sophisticated structures involved in data, is employed to model the relationship between the roadheader performance and the parameters influencing the tunneling operations with a high correlation. The database used in modeling is compiled from laboratory studies conducted at Azad University at Science and Research Branch, Tehran, Iran. A model with architecture 4-10-1 trained by back-propagation algorithm is found to be optimum. A multiple variable regression (MVR) analysis is also applied to compare performance of the neural network. The results demonstrate that predictive capability of the ANN model is better than that of the MVR model. It is concluded that roadheader performance could be accurately predicted as a function of unconfined compressive strength, Brazilian tensile strength, rock quality designation, and alpha angle R ² = 0.987. Sensitivity analysis reveals that the most effective parameter on roadheader performance is the unconfined compressive strength.     

Fabrication of magnetic β-CD/chitosan nanocomposite as an efficient and recyclable dye adsorbent

ABSTRACT

In this work, novel magnetic nanocomposite adsorbents were prepared by crosslinking β-cyclodextrin (β-CD) onto chitosan backbones by using epichlorohydrin as a crosslinker and in the presence of Fe₃O₄ nanoparticles. The composition of β-CD-chitosan nanocomposites was characterized via FTIR, XRD, TEM, SEM, and VSM. Then, the as-prepared nanocomposites were treated for elimination of methyl orange (MO). The results indicated that the adsorption of MO exhibited a maximum adsorption capacity of 314 mg g^?1 at 25°C. Moreover, the rates and isotherm data of adsorption matched excellent at different MO concentrations (10, 60, and 120 mg/L) using second-order and Langmuir models with the regression coefficient (R²) of 0.9993 and 9990, respectively. Besides, the thermodynamic data confirmed MO adsorption as an endothermic process. The adsorbent was also confirmed as good materials for re-use and maintained 88% of its initial adsorption capacity for MO after the fifth regeneration cycles. In conclusion, the synthesized magnetic nanocomposites can be applied as cost-effective dye adsorbents with high regeneration efficiency.     

Predicting missing contacts in mobile social networks

Experimentally measured contact traces, such as those obtained in a conference setting by using short range wireless sensors, are usually limited with respect to the practical number of sensors that can be deployed as well as the number of available human volunteers. Moreover, most previous experiments in this field can report only partial contact information since not everyone participating in the experiment carries a sensor device. Previously collected contact traces have significantly contributed to the development of more realistic human mobility models. This in turn has influenced proposed routing algorithms for Delay Tolerant Networks where human contacts play a vital role in message delivery. By exploiting time-spatial properties of contact graphs as well as the popularity and social information of mobile nodes, we propose a novel method to reconstruct the missing parts of contact graphs where only a subset of nodes are able to sense contacts.     

Stability analysis in nuclear reactor using Lyapunov exponent

A simple model for nuclear reactor is proposed. With increasing the fuel concentration, our minimal model shows two successive phases; subcritical and supercritical. In subcritical regime, the neutron population grows with increasing the fuel concentration. In the supercritical state, the Lyapunov exponent is positive implying that the neutron diffusion phenomena are spatiotemporal chaos. In the present paper, the infinite multiplication factor curve is qualitatively reproduced for fuel concentration. We have derived the critical fuel concentration based on the Lyapunov exponents. The basic objective of the work is to improve the prediction of the critical neutron population with respect to the fuel concentration.     

Thermal Buckling of Imperfect Deep Functionally Graded Spherical Shell

Thermal buckling analysis of deep imperfect functionally graded (FGM) spherical shell is considered in this paper. A mixture of ceramic and metal is considered for the FGM shell and the material properties, such as the modulus of elasticity and coefficient of thermal expansion, vary by a power law function through the thickness. Employing the Sanders non-linear kinematic relations, total potential energy function is derived and the equilibrium and stability equations are obtained for the imperfect shell. Approximate solutions satisfying the simply supported boundary condition are assumed and using the Galerkin method the error due to the approximation is minimized. The geometrically imperfect shell is considered and three types of thermal loadings, such as the uniform temperature rise (UTR), linear temperature rise through the thickness (LTR), and non-linear temperature rise through the thickness (NLTR) are considered and their associated buckling temperatures are obtained. The effects of different temperature functions and the magnitude of initial geometric imperfection are examined on the thermal buckling loads of the shell.     

Impact Behavior of Intrinsically Brittle Nanoparticles: A Molecular Dynamics Perspective

Impact behavior of intrinsically brittle materials at the nanoscale is a topic of growing interest, for instance, in aerosol deposition and cold spraying of ceramic materials. In this work, we examine the behavior of single-crystalline brittle nanoparticles upon impact on a rigid substrate, within the framework of a molecular dynamics model. The model is based on Lennard-Jones formulation, where brittleness is brought about by using a relatively small cut-off interaction distance. Simulations have been carried out for different values of particle size and velocity. The results show that despite the induced brittleness, particles start to deform without breaking into fragments, as the particle size falls below a critical value. They also indicate that the deformation of particles can be accompanied by poly-crystallization and bonding to the substrate. The necessary conditions for deformation and bonding are also predicted in view of an analytical model of impact and fracture, considering the effects of particle size and surface energy. The results are summarized into a parameter selection map, providing an overview of the conditions for successful deposition of intrinsically brittle materials, in terms of particle size and velocity. The predictions are interpreted with respect to the results of the relevant kinetic spraying studies.     

On the Analysis of Well Test Data Influenced by Capillary Pressure

The focus of this study is on the analysis of capillary pressure effects on well test data. Ignoring the capillary pressure is one of the assumptions that have been applied in all multiphase well test analysis approaches. In this work we investigate the influences of capillary pressure on the analysis of pressure transient data in a solution gas drive reservoir and in a reservoir containing oil and water. Reservoir simulations were performed to generate pressure and saturation data for each case and the pressure responses and the fluids saturation distribution for drawdown and build-up tests for two cases with and without capillary pressure are compared. According to the results of this study, it has been concluded that the influences of capillary pressure on fluids saturation behavior in build-up test due to importance of capillary force than viscose force in this period is more noticeable. Though the effects of capillary pressure lead to differences in the fluids saturation behavior but the authors have not observed dissimilarity in the pressure responses affected by capillary pressure for draw down and build-up test in the both reservoirs under study.     

Influence of the sunflower oil content,cooking temperature and cooking time on the physical and sensory properties of spreadable cheese analogues based on UF white‐brined cheese

In this study, a cheese analogue was produced based on UF white‐brined cheese by replacing the dairy fat with sunflower oil and cooking at different temperatures and times. Hardness, adhesiveness, meltability and oiling‐off were used to evaluate the suitability of the final product. Partial replacement of dairy cream with sunflower oil led to an increase in the adhesiveness, oiling‐off and spreadability while decreasing the hardness of the cheese. Optimum operating conditions were found to be 85 °C for the cooking temperature, 14.12 min for the cooking time and 27.14% w/w for the sunflower oil content.     

Construction of deformed photon-added nonlinear coherent states with negative m for the one-mode field in a Kerr medium

In this paper, based on the nonlinear coherent states formalism and using the Hamiltonian for a single mode field in a Kerr medium, the deformed photon-added nonlinear coherent states with negative m corresponding to the nonharmonic oscillators are constructed. In addition, some of the nonclassical properties associated with these states such as the Mandel parameter, quadrature squeezing and second-order correlation function are investigated. It is found that the deformed photon-added nonlinear coherent states with negative m for the one-mode field in a Kerr medium are nonclassical states.     

Efficient co‐cultivation of human fibroblast cells (HFCs) and adipose‐derived stem cells (ADSs) on gelatin/PLCL nanofiber

In this study, we investigated whether the nanofibers produced by natural‐synthetic polymers can probably promote the proliferation of co‐cultured adipose‐derived stem cells/human fibroblast cells (ADSs/HFCs) and synthesis of collagen. Nanofiber was fabricated by blending gelatin and poly (L‐lactide co‐ɛ‐caprolactone) (PLCL) polymer nanofiber (Gel/PLCL). Cell morphology and the interaction between cells and Gel/PLCL nanofiber were evaluated by FESEM and fluorescent microscopy. MTS assay and quantitative real‐time polymerase chain reaction were applied to assess the proliferation of co‐cultured ADSs/HFCs and the collagen type I and III synthesis, respectively. The concentrations of two cytokines including fibroblast growth factor‐basic and transforming growth factor‐β1 were also measured in culture medium of co‐cultured ADSs/HDCs using enzyme‐linked immunosorbent assay assay. Actually, nanofibers exhibited proper structural properties in terms of stability in cell proliferation and toxicity analysis processes. Gel/PLCL nanofiber promoted the growth and the adhesion of HFCs. Our results showed in contact co‐culture of ADSs/HFCs on the Gel/PLCL nanofiber increased cellular adhesion and proliferation synergistically compared to non‐coated plate. Also, synthesis of collagen and cytokines secretion of co‐cultured ADSs/HFCs on Gel/PLCL scaffolds is significantly higher than non‐coated plates. To conclude, the results suggest that Gel/PLCL nanofiber can imitate physiological characteristics in vivo and enhance the efficacy of co‐cultured ADSs/HFCs in wound healing process.Inspec keywords: biomedical materials, enzymes, adhesion, fluorescence, polymer fibres, tissue engineering, wounds, nanofibres, cellular biophysics, molecular biophysics, gelatin, biochemistry, nanomedicine, field emission scanning electron microscopy, nanofabricationOther keywords: cell morphology, cell proliferation, efficient cocultivation, HFCs, ADSs, gelatin‐PLCL nanofiber, natural‐synthetic polymers, cocultured adipose‐derived stem cells‐human fibroblast cells, FESEM, fluorescent microscopy, MTS assay, quantitative real‐time polymerase chain reaction, collagen type I synthesis, collagen type III synthesis, cytokines, transforming growth factor‐β1, fibroblast growth factor‐basic growth factor‐β1, culture medium, enzyme‐linked immunosorbent assay assay, structural properties, toxicity analysis, cellular adhesion, physiological characteristics in vivo, wound healing