Coupled Diffusional/Displacive Transformations

The displacive transformation of austenite to ferrite in steels containing both substitutional and interstitial elements has been studied. The aim was to establish the conditions under which plates of the product phase can form with a partial redistribution of the interstitial element during nonequilibrium nucleation and growth. An earlier model describing such 'coupled diffusional/displacive transformation' (CDDT) has been applied over a wide range of carbon concentrations, revealing a variety of discrepancies. It was found that the theory correctly predicts the variation in the martensite-start temperature with carbon concentration, but fails to estimate the corresponding changes in the bainite-start temperatures of the same steels. Thus, the accuracy claimed by the original theory appears fortuitous for bainite. The failure is attributed to the fact that the model does not include any variation in the stored energy as a function of transformation temperature. The nature of the required variation in stored energy with temperature was calculated by fitting against available data and the CDDT model was modified appropriately. The estimated variation in stored energy is consistent with an expectation that when the yield strength is exceeded at a high enough temperature, plastic accommodation of the shape change should lead to a reduction in the stored energy. The modified model predicted a sharper transition from growth involving full partitioning of carbon, to diffusionless growth when applied to a number of alloyed steels. This abrupt transition from paraequilibrium to diffusionless growth is in fact consistent with experiments; Widmanstatten ferrite at all temperatures is known to grow at a rate controlled by the diffusion of carbon in the austenite ahead of the interface, whereas the growth rate of bainite subunits is much larger then might be expected from carbon diffusion-controlled growth. Considerable work is also reported on how bainite transformation might be described by the CDDT model, but significant difficulties remain. Another model was developed to study the kinetics of the partitioning of carbon from supersaturated ferrite into residual austenite. The time required was estimated analytically and using a finite difference model. It was found that in all the cases investigated, the analytical solution underestimates the diffusion time, the discrepancy increasing at lower temperatures, or when the concentration of substitutional solutes which stabilise austenite is reduced. This is attributed to the fact that the analytical method fails to take account of the coupling of the diffusion fluxes that arise in both the austenite and the ferrite. The results were first discussed in the context of displacive transformations in steels. The model was latter extended to the non-ferrous, Ag-44.9Cd at.% alloy. This alloy undergoes a $\beta$$_{2}$ - $\alpha$$_{1}$ transformation which is sometimes called "bainite" by virtue of the fact that the plates appear to be different in composition from the parent phase. The $\alpha$$_{1}$ plates could on the other hand, form without diffusion, the cadmium partitioning into the $\beta$$_{2}$ matrix after formation. The results are compared with published data, but they indicate that there is a need for more accurate diffusion data before definitive conclusions can be made on the mechanism of transformation

Machine Health Monitoring and Fault Diagnosis Techniques Review in Industrial Power-Line Network

The machinery arrangements in industrial environment normally consist of motors of diverse sizes and specifications that are provided power and connected with common power-bus. The power-line could be act as a good source for travelling the signal through power-line network and this can be leave a faulty symptom while inspection of motors. This influence on other neighbouring motors with noisy signal that may present some type of fault condition in healthy motors. Further intricacy arises when this type of signal is propagated on power-line network by motors at different slip speeds, power rating and many faulty motors within the network. This sort of convolution and diversification of signals from multiple motors makes it challenging to measure and accurately relate to a certain motor or specific fault. This chapter presents a critical literature review analysis on machine-fault diagnosis and its related topics. The review covers a wide range of recent literature in this problem domain. A significant related research development and contribution of different areas regarding fault diagnosis and traceability within power-line networks will be discussed in detail throughout this chapter

Robust adaptive anti-synchronization control of multiple uncertain chaotic systems of different orders

The precise anti-synchronization control of uncertain chaotic systems has always remained an interesting problem. The anti-synchronization control of multiple different orders uncertain chaotic systems increases the complexity and enhances the security of the information signal in secure communications. Hence, it confines the hacking in digital communication systems. This paper proposes a novel adaptive control technique and studies the double combination anti-synchronization of multiple different orders uncertain chaotic systems. The proposed adaptive feedback control technique consists of three fundamental nonlinear components. Each component accomplishes a different objective; (i) stability of the closed-loop, (ii) smooth and fast convergence behaviour of the anti-synchronization error, and (iii) disturbance rejection. The theoretical analysis in (i) to (iii) uses the Lyapunov stability theory. This paper also provides parameters adaptation laws that stabilize the uncertain parameters to some constants. The paper discusses the simulation results of two representative examples of four different orders uncertain chaotic systems. These examples demonstrate anti-synchronization among hyperchaotic Lü, uncertain chaotic Shimizu Morioka, uncertain second-order nonlinear duffing, and uncertain parametrically excited second-order nonlinear pendulum systems. The computer-based simulation results certify the efficiency and performance of the proposed anti-synchronization control approach and compare them with peer works

Ibn Khaldun’s Views on Man, Society and State in the Light of al-Muqaddimah

The discipline of sociology emerged in the Modern West not more than two centuries ago. The main sociological themes, especially about an individual and society, seems to be incoherent rather contradictory as there are a plethora of opinions of sociologists regarding positioning the place of an individual and society. One group of sociologists lay tremendous emphasis upon the open-ended and unlimited freedom of an individual and denies any social or state intervention in deciding the fate thereof (Ackerman, 2008). On the other hand, other group of sociologists put all their efforts to over-emphasise the significance of society or state whereby the role of an individual is narrowed or reduced to be merely a tool in the whole mechanism of state machinery (MacKinnon, 2000). The fact is that both are important for over-all development and reducing the role of either aspects will culminate at grave imbalance in the existing world. The emergence of Modern Western powers, after multitude of layers of dark ages, assumed the charge of all walks of life not only in so-called developed countries rather influenced the thought and style of Asian and African countries as well. The mega project was to ensure and export the sociological underpinnings based on Euro-centric model of globe to the third world. This paper is a humble effort to bring forth the much coherent and refined ideas about an individual and society. Ibn Khaldun, way before the emergence of Modern sociology, laid the foundation of the discipline and discussed valuable discourses about mainstream themes of sociology in general and about man and society in particular. He sees a natural coherence and a systematic progression between an individual and society. The aim of this paper is to investigate the views of Ibn Khaldun regarding an individual and society in the light of his magnum opus Al-Muqaddimah. The researcher has ensured to quote directly from the main source with reference to Arabic passages to retain the originality of work. The significance of the study is that it helps exploring the views of Muslim sociologist Ibn Khaldun other than the western prism. Ibn Khaldun explains the full account of an individual, society and state and deliberates upon the unique social orientation of human beings

THE DURABILITY ASPECTS AND BOND STRENGTH OF RUBBERCRETE CONTAINING NANO SILICA

Crumb rubber is product from the processed waste scrap tire which is non-biodegradable and threat to environment. One of common usage of crumb rubber is production of concrete containing crumb rubber or rubbercrete. Rubbercrete contribute a lot of benefits such low density, good thermal resistivity, and high ductility. Adverse effect of rubbercrete strength of the concrete is decreased as percentage of crumb rubber added increased. This is due to physical properties of crumb rubber that repels water make the adhesion between cement and aggregate decreased. Nano silica is widely used nowadays and found can increase the compressive strength of concrete. Nanosilica works as filler in the empty spaces in the concrete particles. It acts as nucleation of the hydrated products resulting in the improvement of concrete hydration rate of the concrete proving in the high early strength of concrete containing nano silica. Thus nano silica is proven can improve the transition zone between aggregates and cement paste. Hence, in this research, we believe by adding nano silica in the rubbercrete, the nano silica will overcome the problem of decreasing in strength of rubbercrete as a matter of fact, creating a concrete that have both high ductile properties and high strength. In these studies, 0, 5, 10, 15, and 20 weights % of rubber crumbs with respect to fine aggregate is added to the concrete. The type of w/c used for the concrete containing crumb rubber is 0.41, 0.57 and 0.68 accordingly. For increasing the concrete compressive strength, 1, 3 and 5% of nano silica were introduced to the rubber containing concrete with respect to cementitios material. For the concrete containing nano silica and crumb rubber the w/c ratio used only 0.57. The mixture schemes for measuring the 28 day compressive strengths and bond strength were performed according to ACI standard. After that the durability aspect and bond strength of the concrete were tested according to BS EN 12393 and ASTM C234 1999. Result show that by adding nano silica in the concrete mixture containing crumb rubber, it counterpart the weakness of cubbercrete which low in strength. The porosity and permeability of the concrete also decrease by adding nano silica in the rubbercrete

Advocacy journalism and climate justice in a Global Southern country

Being among the world’s most affected countries by climate change, Pakistan is facing a variety of cases of climate injustice committed by internal and external drivers. Waisbord’s referred “Advocate-journalist” model carries a good potential to advocate these injustices to stimulate democratic dialogue among the audience that eventually pushes leadership to make eco-friendly policies. This study critically analyses advocacy journalism coverage of cases of local and regional climate injustice in the editorial contents of mainstream Pakistani newspapers by using the quantitative content analysis method. Results reveal that selected newspapers gave inappropriate coverage to climate injustice issues both in quantity and quality. Besides muddled local and regional climate injustice issues’ priorities, editorialists also excessively recommended dirty energy solutions to the policymakers. The final analysis suggests that the findings of climate and energy-related scientific studies were not being reflected in the advocacy journalism contents as well. This failure of “advocate-journalist” model to perform its normative role of potentially advocating the cases of climate injustice with compelling scientific evidence seems to attribute to the political economy of the press or editorial inattention. As a way out of this journalistic lack, Waisbord’s endorsed “civic advocacy” groups must intervene to plug the loopholes

Experimental investigation on synthesis, characterization, stability, thermo-physical properties and rheological behavior of MWCNTs-kapok seed oil based nanofluid

Several researchers devoted their efforts for the thermal conductivity enhancement of Carbon Nanotubes (CNTs) based nanofluids as CNTs have excellent thermal properties. However, limited research is reported on the detailed thermo-physical properties of CNTs and oil based nanofluids. In this work, the one-step method synthesis of a new MWCNTs-Kapok seed oil based nanofluid at constant nanoparticle concentration (0.1 wt./wt.) is reported. The nanofluid is characterized by FESEM, FTIR, visual stability analysis and thermophysical properties are experimentally measured. The viscosity found in the range of (0.049–10.101¿Pa·s), the thermal conductivity of (0.165–0.207¿W/m·K) and enhancement of thermal conductivity (6.1538%) were observed. Moreover, the viscosity decreases, and thermal conductivity increases with an increase in temperature. The experimentally obtained data are found in agreement with existing models and modified correlations. The rheological behavior showed that nanofluid is non-Newtonian in nature and exhibiting shear thinning or pseudo plastic behavior.Preprin