Sharif Digital Repository

High strength TRIP-aided steel sheets with high formability and better ductility are of industrial interest. Texture control and retained austenite characterization are considered as the main factors with respect to the formability and ductility. Processing parameter such as initial conditions of hot rolling, cold rolling to final size of sheet, intercritical annealing after cold rolling and subsequent isothermal heat treatment to achieve TRIP specification in product, affect bulk texture of sheets. Moreover, chemical composition of steel should be noted especially because it can change the intensity of orientation and final macro texture of sheet. In this work, the effect of cold rolling... 

Optimization of high strength and high formability of multiphase cold rolled sheet TRIP-aided steels is based on the composition and the austempering conditions. The effect of intercritical annealing temperature on the volume fraction and carbon concentration of the retained austenite was investigated in two different TRIP-aided steels. Experimental results show that the optimum annealing temperatures are 860 °C for Al-containing and 810 °C for Si-containing TRIP steels. It was demonstrated that the measurement of retained austenite can be successfully performed for textured TRIP steels by XRD. © 2006 Elsevier Inc. All rights reserved  

In developed multiphase high strength, high formability TRIP-aided steel, Luders bands are observed similar to conventional low carbon steels. Retained austenite as the most effective constituent in TRIP steels, is responsible for Luders band formation as well as other properties such as formability, physical and mechanical properties. In the present study, a correlation between the Luders strain and the retained austenite characterization is proposed and verified by experimental evidences of the work carried out on two types of TRIP steel sheets. Intercritical annealing of cold rolled TRIP steels at different temperatures change the volume fraction of the retained austenite as well as the... 

Being able to track objects that surround us is key for planning actions in dynamic environments. However, rigorous cognitive models for tracking of one or more objects are currently lacking. In this study, we asked human subjects to judge the time to contact (TTC) a finish line for one or two objects that became invisible shortly after moving. We showed that the pattern of subject responses had an error variance best explained by an inverse Gaussian distribution and consistent with the output of a biased drift-diffusion model. Furthermore, we demonstrated that the pattern of errors made when tracking two objects showed a level of dependence that was consistent with subjects using a single... 

In this research, the interaction between electroencephalogram (EEG) and, a cardiac parameter, photoplethysmogram (PPG), using connectivity measures to emphasize the importance of autonomic nervous system over the central nervous system during a deception is investigated. In this survey, connectivity analysis was applied, since it can provide information flow of brain regions; moreover, lying and truth appear to be cohered with the flow of information in the brain. Initially, a new wavelet-based approach for EEG/PPG effective connectivity fusion was introduced; then, it was validated for 41 subjects. For each subject, after extracting specific wavelet component of EEG and PPG signals, an... 

Deception is mentioned as an expression or action which hides the truth and deception detection as a concept to uncover the truth. In this research, a connectivity analysis of Electro Encephalography study is presented regarding cognitive processes of an instructed liar/truth-teller about identity during an interview. In this survey, connectivity analysis is applied because it can provide unique information about brain activity patterns of lying and interaction among brain regions. The novelty of this paper lies in applying an open-ended questions interview protocol during EEG recording. We recruited 40 healthy participants to record EEG signal during the interview. For each subject,... 

In this work, the effect of hot deformation temperature on microstructure and mechanical properties of micro alloyed steel was studied. The results indicated that by decreasing the deformation temperature final microstructure is refined and the volume fraction of grain boundary ferrite is increased and some pearlite is produced. Therefore both the yield strength and ultimate tensile strength is increased, while the toughness is preserved in comparison to a ferritic-pearlitic microstructure. Also a model was developed to relate the deformation condition to the volume fraction of acicular ferrite at mixed microstructure. © 2008 Elsevier Ltd. All rights reserved  

The effect of cooling rate after hot deformation on the microstructure and mechanical properties of a commercial microalloyed forging steel (30MSV6 grade) was investigated using the hot compression test. Hot compression test was performed at 1150 and 925 °C followed by air cooling at different rates. Final microstructures and mechanical properties were evaluated by optical microscopy and shear punch test (SPT), respectively. The results indicated that by increasing the cooling rate, the as-received ferritic-pearlitic microstructure changes to the acicular ferrite, bainite or martensite. It is shown that both yield and ultimate strength increase but the ductility decreases significantly. At a... 

Axial crushing behavior and crashworthiness characteristics of thin-walled steel tubes containing annular grooves are experimentally studied. The grooves determine the position of the folds and control the buckling mode of deformation. The aims are improving the uniformity of the load-displacement behavior and predicting energy absorption capacity of the tubes. Grooves are cut circumferentially and alternately inside and outside the tubes at predetermined intervals, Quasi-static axial crushing tests are performed with different groove distances. Photographs are taken during axial buckling and the specimens after crushing are sectioned axially to carry out the measurements. The deformation... 

The initial buckling load of a tube corresponds to the peak load in the first buckling cycle. In practice, this load is very important for crashworthiness design that gives an indication of the force required to initiate collapse and hence begin the energy absorption process. In this paper, the effects of grooves on the initial buckling load of thin-walled tubes under axial compression are investigated. The grooves are introduced in the tube to force the plastic deformation to occur at predetermined intervals along the tube. The aims are improve the uniformity of the load-displacement behaviour of axially crushed tubes, predict and control the collapse load of the tube. An analytical study... 

Crashworthiness characteristics of thin-walled steel tubes containing annular grooves are experimentally studied. The grooves are introduced in the tube to force the plastic deformation to occur at predetermined intervals along the tube. The aims are improving the uniformity of the load-displacement behaviour and predicting energy absorption capacity of the tubes. Quasi-static axial crushing tests are performed with different groove distances. Load-displacement curves are described and energy absorption and mean post-buckling load are determined. The results show that the load-displacement curve and energy absorbed by the axial crushing of tubes could be controlled by the introduction of... 

Supercritical fluid extraction is a new technology that could be effectively used to treat oil-contaminated drill cuttings generated during drilling for oil and gas. In this work, the solubility of oil-contaminated drill cuttings in supercritical carbon dioxide is obtained by an experimental flow type apparatus. The solubility was measured at 200 bar pressure, over a temperature range of 55-79.5°C. The measured solubility and experimental data for oil in drill cuttings were correlated using the PC-SAFT, PR and SRK EOS models, without any adjustable parameters. Average absolute derivations of less than 15.1 %, 98.7 %, and 99.3 % are achieved between predicted and experimental values for the... 

The influence of different parameters such as welding pressure, rotational speed, and traverse speed on the weld properties has been evaluated earlier but there are some important parameters yet to be thoroughly investigated. In this study, an effort has been made to determine the influence of different ratios of rotational speed/traverse speed on mechanical properties of different zones of friction stir welded AZ31 magnesium alloy. Mechanical properties of different zones were determined by a shear punch test. It was found out that increasing the aforementioned ratio leads to a slight decrease in yield and ultimate strength of the stir zone and the transitional zone. It was also observed... 

In engineering practice, the space occupied by high conductivity materials together with the cost are the two elements of major concern. Therefore, seeking for more efficient designs of high conductivity pathways ('inserts'), embedded into a heat generating body constitutes a formidable challenge. The main idea of this paper is to introduce new patterns for the highly conductive pathways, called 'fork-shaped' configurations. Essentially, two types of fork-shaped pathways, 'F1' and 'F2' are introduced. Numerical results demonstrate that, these two configurations of highly conductive pathways, remarkably surpass the latest configurations reported in the literature, with the same amount of high... 

This paper presents a novel hybrid approach for intrusion detection in computer networks. The proposed approach combines an evolutionary based fuzzy system with an artificial immune system to generate high quality fuzzy classification rules. The performance of final fuzzy classification system has been investigated using the KDD-Cup99 benchmark dataset. The results indicate that in comparison to several traditional techniques, such as C4.5, Naïve Bayes, k-NN and SVM, the proposed hybrid approach achieves better classification accuracies for most of the classes of the intrusion detection classification problem. Therefore, the resulted fuzzy classification rules can be used to produce a... 

Introduction: The application of doxorubicin (DOX) in cancer therapy has been limited due to its drug resistance and poor internalization. Graphene oxide (GO) nanostructures have the capacity for DOX delivery while promoting its cytotoxicity in cancer. Areas covered: The favorable characteristics of GO nanocomposites, preparation method, and application in cancer therapy are described. Then, DOX resistance in cancer, GO-mediated photothermal therapy, and DOX delivery for cancer suppression are described. Preparation of stimuli-responsive GO nanocomposites, surface functionalization, hybrid nanoparticles, and theranostic applications are emphasized in DOX chemotherapy. Expert opinion: GO... 

A novel intelligent semi-active control system for an eleven degrees of freedom passenger car's suspension system using magnetorheological (MR) damper with neuro-fuzzy (NF) control strategy to enhance desired suspension performance is proposed. In comparison with earlier studies, an improvement in problem modeling is made. The proposed method consists of two parts: a fuzzy control strategy to establish an efficient controller to improve ride comfort and road handling (RCH) and an inverse mapping model to estimate the force needed for a semi-active damper. The fuzzy logic rules are extracted based on Sugeno inference engine. The inverse mapping model is based on an artificial neural network... 

Using CNG as an additive for gasoline is a proper choice due to higher octane number of CNG enriched gasoline with respect to that of gasoline. As a result, it is possible to use gasoline with lower octane number in the engine. This would also mean the increase of compression ratio in SI engines resulting in higher performance and lower gasoline consumption. Over the years, the use of simulation codes to model the thermodynamic cycle of an internal combustion engine have developed tools for more efficient engine designs and fuel combustion. In this study, a thermodynamic cycle simulation of a conventional four-stroke spark-ignition engine has been developed. The model is used to study the... 

With the declining energy resources and increase of pollutant emissions, a great deal of efforts has been focused on the development of alternatives for fossil fuels. One of the promising alternative fuels to gasoline in the internal combustion engine is natural gas [1-5]. The application of natural gas in current internal combustion engines is realistic due to its many benefits. The higher thermal efficiency due to the higher octane value and lower exhaust emissions including CO2 as a result of the lower carbon to hydrogen ratio of the fuel are the two important feature of using CNG as an alternative fuel. It is well known that computer simulation codes are valuable economically as a cost...