Evaluation of Centrifugal Casting Process Parameters for In Situ Fabricated Functionally Gradient Fe-TiC Composite

A gradient Fe-TiC composite was successfully produced via combination of in situ reaction with centrifugal casting techniques. Additionally, some of the effective parameters of the centrifugal casting process have been studied. Cast iron and ferrotitanium, which were used as raw materials, were melted using a high-frequency induction furnace coupled with centrifugal equipment. The microstructure and phase characterization of the fabricated composite was studied by scanning electron microscopy, optical microscopy, and X-ray diffraction. The results show that the production of a pearlite matrix composite reinforced by TiC particles is feasible. The distribution of TiC in the pearlitic matrix is completely uneven as a result of density difference between molten medium and TiC in the centrifugal casting process.     

The combustion behavior of epoxy-based multifunctional electrolytes

Multifunctional or structural electrolytes are characterized by ionic conductivity high enough to be used in the electrochemical devices and mechanical performance suitable for the structural applications. Preliminary insights are provided into the combustion behavior of structural bi-continuous electrolytes based on bisphenol A diglycidyl ether (DGEBA), synthesized using the techniques of reaction induced phase separation and emulsion templating. The effect of the composition of the structural electrolytes and external heat flux on the behavior of the formulations were studied using a cone calorimeter with gases formed during testing analyzed using FTIR. The composition of the formulations investigated was changed by varying the type and amount of the ion conductive part of the bi-continuous electrolyte. Two ionic liquids, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-TFSI) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF₄), as well as a deep eutectic solvent (DES) based on ethylene glycol and choline chloride, were used. The results obtained confirm that time to ignition, heat release rate (HRR), total mass loss, as well as the composition of the gases released during tests depend on the composition of the formulations. Addition of liquid electrolyte is found to reduce the time to ignition by up to 10% and the burning time by between 28% and 60% with the added benefit of reducing the HRR by at least 34%. Gaseous products such as CO₂, CO, H₂O, CH₄, C₂H₂, N₂O, NO, and HCN were detected for all formulations with the gases SO₂, NH₃, HCl, C₂H₄, and NH₃ found to be for certain formulations only.     

Calculation of equilibrium composition in combustion products

For a specific combustion problem involving calculations of several species at equilibrium, it is much simpler to write a special computer program and calculate the concentrations, rather than to use a generalized computer program. To calculate these concentrations, one must solve a set of non-linear algebraic equations. This work describes a procedure in which the Newton-Raphson method and the successive substitution method are combined. It is was found that for these types of problems the value of unknowns and the nature of the equations are such that by adopting the two procedures simultaneously a much faster and reliable convergence is achieved. This study also shows what possible species should be considered for these calculations.     

Reviewing the transport domain: an evolutionary bibliometrics and network analysis

Tracing the trajectory of scientific fields has been recognized by informaticians, nonetheless, little effort has been dedicated to understanding the evolution of the fast-moving research field of transport, quantitatively and qualitatively. This paper identifies intellectual turning points and emerging trends in the area of transport. Using bibliometric methods, co-keyword networks, journal co-citation networks, highly cited categories, and country and institute networks are detected, visualized and discussed. To conduct this analysis, all publications (35,712) in 23 top journals in the field of transport are extracted from the Institute for Scientific Information (Web of Science). The output of this article could be a valuable source for academics and practitioners working in the field of transport planning and those who work in the areas having a strong relationship with transport issues including mathematicians, economics, operation research, management and geography.     

Analytical cracking load estimation of Laminated Veneer Lumber (LVL) beams with holes

Predicting the load-carrying capacity of timber beams with holes cannot be performed by usual analysis methods if the failure of the beam is governed by the crack initiation and propagation around the hole at low load levels. Predicting the cracking load is an important design issue because it corresponds to the load-carrying capacity of the timber beam before the crack propagation. One of the models that can be used for the fracture formulation is that of a beam on elastic foundation. In this model a part of the beam is assumed to follow the conditions of beam with elastic foundation which has spring stiffness equal to the fracture properties of the material in the crack surface. Based on beam on elastic foundation model, the cracking load prediction is the target of the paper. Some closed form solutions for the beam with hole are presented. The formulation has been derived for two cases of pure shear and pure bending moment. Finally a semi-empirical formulation for combination of shear and bending moment in the section is presented. The model predictions are compared with the results of an experimental program showing good correlation. The analytical model can therefore be proposed for future revisions of codes of practice such as the Eurocode 5.     

An algorithm on sign words extraction and recognition of continuous Persian sign language based on motion and shape features of hands

Sign language is the most important means of communication for deaf people. Given the lack of familiarity of non-deaf people with the language of deaf people, designing a translator system which facilitates the communication of deaf people with the surrounding environment seems to be necessary. The system of translating the sign language into spoken languages should be able to identify the gestures in sign language videos. Consequently, this study provides a system based on machine vision to recognize the signs in continuous Persian sign language video. This system generally consists of two main phases of sign words extraction and their classification. Several stages, including tracking and separating the sign words, are conducted in the sign word extraction phase. The most challenging part of this process is separation of sign words from video sequences. To do this, a new algorithm is presented which is capable of detecting accurate boundaries of words in the Persian sign language video. This algorithm decomposes sign language video into the sign words using motion and hand shape features, leading to more favorable results compared to the other methods presented in the literature. In the classification phase, separated words are classified and recognized using hidden Markov model and hybrid KNN-DTW algorithm, respectively. Due to the lack of proper database on Persian sign language, the authors prepared a database including several sentences and words performed by three signers. Simulation of proposed words boundary detection and classification algorithms on the above database led to the promising results. The results indicated an average rate of 93.73 % for accurate words boundary detection algorithm and the average rate of 92.4 and 92.3 % for words recognition using hands motion and shape features, respectively.     

Alteration of ADP-ribosylation in aging rat brain astrocytes

DNA damage and the enzyme poly (ADP-ribose) polymerase (PARP) associated with the pathogenesis of numerous age-related neurodegenerative disorders. Astrocytes play crucial roles in both support metabolic functions and cell viability of the brain. PARP regulates DNA damage and repair in the brain cells. In this study PARP activity and DNA strand break were investigated in the astrocytes isolated from young and aged rat brain. Three and 30-month-old rats were killed by decapitation and brains were removed onto an ice cooled glass plate. Astrocytes were isolated by sucrose density gradient centrifugation and glutamine synthetase (GS) served as a marker of the astrocytes lineage. The specific activity of PARP was assayed in permeabilized cells by measuring the incorporation of the ADPribose moiety of [3H]NAD into the nuclear acceptor proteins. The rate of DNA strand breaks was determined using a fluorescent dye and monitored spectrofluorimetry. An increase (about 75%) in the PARP activity was observed in the whole homogenates of aged rats, whereas this rise was more pronounced (about 360%) when the reaction was measured in the purified astrocyte preparations. The amount of DNA strand breaks was also higher in the astrocytes isolated from the aged brain as compared to that of young levels. The close relationship between the level of DNA strand breaks and PARP activity in the astrocytes suggest that these cells are susceptible to the metabolic alterations in aging. It is concluded that the astrocytes PARP might be considered as a therapeutic target for combating age related neurodegenerative disorders.     

A generalized model to predict minimum particle transport velocities in multiphase air–water horizontal pipes

A new model is proposed to predict minimum flow rates required to constantly move particles in both intermittent and stratified flow regimes. The new model consists of a single‐phase flow model along with an appropriate length scale to be extended to multiphase flow regime. A comparison of the new model with experimental data in a multiphase air–water flow shows that the new model is able to predict minimum flow rates well for a wide range of operating conditions. The new model can capture the effects of particle size, particle concentration, and pipe size as confirmed by experimental data. A comparison of the new model with previously proposed models in the literature shows that the new model improves critical velocity predictions significantly. Moreover, the new model is the only model that takes into account the effect of particle concentration and can predict critical velocity in both intermittent and stratified flow regimes. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2634–2646, 2015