Advanced Filler Network Characterization in Rubber

The present work is aimed at introducing new characterization techniques in filled rubber compounds. Rubber fillers such as carbon black are often used to enhance the physical properties of rubber compounds. With a sufficient amount of carbon black, a percolated filler network is formed, spanning the volume of the rubber compound. This phenomenon not only significantly improves the mechanical material behaviour, but also introduces a more complex mechanical response. Further enhancement is possible with the addition of reinforcing resins such as Novolaks, phenol–formaldehyde resins with a formaldehyde-to-phenol molar ratio of less than one. Based on the systematic studies performed, the two reinforcing materials are observed to exhibit synergistic behaviour resulting from their physical and chemical interaction. The reinforcing resin modifies the activity of the filler surface creating a more compact filler network. This leads to a lower filler network percolation threshold as well as increasing the reinforcing behaviour. This conclusion was derived from various thermo-mechanical measurements such as temperature stress scanning relaxation (TSSR) and dynamic mechanical analysis (DMA). The findings were also validated with advanced microscopical techniques such as atomic force microscopy (AFM) and transmission electron microscopy (TEM). A direct consequence of the filler network is a strain dependent behaviour such as the dynamic and quasi-static strain dependent softening effects known as Payne and Mullins effects, respectively. Within the conventional dynamic mechanical analysis (DMA) of rubber compounds, the mechanical response signal is often assumed to be rheologically linear (sinusoidal function) since in Fourier space, the first harmonic is more pronounced than the subsequent higher harmonics. However, valuable information contained in the higher harmonics can be utilised in order to further characterise the compound properties. One such approach is the large amplitude oscillatory shear (LAOS) technique which analyses the harmonics as a function of large strain deformation. While several studies have contributed to the understanding of this strain dependent nonlinearity, less emphasis was placed on the nonlinearity of the frequency domain. Utilising a resonance-based high frequency DMA, nonlinearities in the frequency domain were established by the observation of the superharmonic resonance, for the first time in rubber technology. Two distinct nonlinearities were observed, polymer induced nonlinearity and filler induced nonlinearity. The new method based on the superharmonic resonance has been successfully applied to characterise the filler network through the evaluation of the microdispersion of carbon black and its interaction with reinforcing resins.Die vorliegende Arbeit hat das Ziel, innovative Methoden zur Charakterisierung von gefüllten Kautschukmischungen einzuführen. Füllstoffe, wie Ruß, werden in Kautschuk eingesetzt, um seine physikalischen Eigenschaften zu verstärken. Mit einer ausreichenden Menge an Ruß wird ein perkolierendes Netzwerk erzeugt, das das Volumen der Kautschukmischung durchdringt. Diese Erscheinung verstärkt nicht nur das mechanische Materialverhalten, sondern führt zu einer komplexeren mechanischen Reaktion. Eine weitere Verstärkung ist durch den Einsatz netzwerkbildender Harze möglich, z.B. von Novolaken, Phenolharzen mit einem Formaldehyd-Phenol-Verhältnis kleiner eins. Auf der Basis von systematischen Studien wird ein synergistisches Verhalten der beiden verstärkenden Materialien infolge ihrer physikalischen und chemischen Wechselwirkung beobachtet. Das Verstärkungsharz verändert die Aktivität der Füllstoffoberfläche und erzeugt damit ein kompakteres Füllstoffnetzwerk. Dies führt zu einer reduzierten Perkolationsschwelle sowie zu einer zusätzlich höheren Verstärkung. Diese Schlussfolgerung wurde aus Messungen mit verschiedenen thermomechanischen Verfahren abgeleitet, wie der anisothermen Spannungsrelaxation (TSSR) und der dynamisch-mechanischen Analyse (DMA). Die Ergebnisse wurden auch mit anspruchsvollen mikroskopischen Techniken validiert, wie der Rasterkraftmikroskopie (AFM) und Transmissionselektronenmikroskopie (TEM). Eine direkte Folge des Füllstoffnetzwerks ist die Entstehung eines dehnungsabhängigen Verhaltens, das als dynamischer oder quasi-statischer Erweichungseffekt beobachtet und jeweils als Payne- oder Mullins-Effekt bezeichnet wird. Bei der dynamisch-mechanischen Analyse (DMA) von Kautschukmischungen wird häufig eine Linearität der Antwort in Bezug auf das angelegte Verformungssignal angenommen, da die Stärke der ersten Harmonischen viel höher ist als die der nachfolgenden Harmonischen. Es gibt jedoch wertvolle Informationen in den höheren Harmonischen, die verwendet werden könnten, um die Materialeigenschaften weiter zu charakterisieren. Ein solcher Ansatz ist die LAOS-Technik (engl. Large Amplitude Oscillatory Shear), mit der die Harmonischen als Funktion der Dehnung analysiert werden. Während einige Studien bereits zum Verständnis dieses dehnungsabhängigen Phänomens beigetragen haben, wurde weniger Wert auf die Nichtlinearität im Frequenzbereich gelegt. Unter Verwendung einer resonanzbasierten Hochfrequenz-DMA wurden erstmals in der Kautschuktechnologie Nichtlinearitäten im Frequenzraum durch Beobachtung von superharmonischen Resonanzen festgestellt. Zwei unterschiedliche Typen von Nichtlinearitäten wurden beobachtet, die polymerinduzierte und die füllstoffinduzierte Nichtlinearität. Die neue Methode auf der Basis der superharmonischen Resonanz wurde zur Charakterisierung des Füllstoffnetzwerkes durch Bewertung der Mikrodispersion von Ruß und dessen Wechselwirkung mit verstärkenden Harzen erfolgreich eingesetzt

Compact rover surveying and laser scanning for BIM development

This paper presents a custom made small rover based surveying, mapping and building information modeling solution. Majority of the commercially available mobile surveying systems are larger in size which restricts their maneuverability in the targeted indoor vicinities. Furthermore their functional cost is unaffordable for low budget projects belonging to developing markets. Keeping in view these challenges, an economical indigenous rover based scanning and mapping system has developed using orthogonal integration of two low cost RPLidar A1 laser scanners. All the instrumentation of the rover has been interfaced with Robot Operating System (ROS) for online processing and recording of all sensorial data. The ROS based pose and map estimations of the rover have performed using Simultaneous Localization and Mapping (SLAM) technique. The perceived class 1 laser scans data belonging to distinct vicinities with variable reflective properties have been successfully tested and validated for required structural modeling. Systematically the recorded scans have been used in offline mode to generate the 3D point cloud map of the surveyed environment. Later the structural planes extraction from the point cloud data has been done using Random Sampling and Consensus (RANSAC) technique. Finally the 2D floor plan and 3D building model have been developed using point cloud processing in appropriate software. Multiple interiors of existing buildings and under construction indoor sites have been scanned, mapped and modelled as presented in this paper. In addition, the validation of the as-built models have been performed by comparing with the actual architecture design of the surveyed buildings. In comparison to available surveying solutions present in the local market, the developed system has been found faster, accurate and user friendly to produce more enhanced structural results with minute details

A Comprehensive Survey on Signcryption Security Mechanisms in Wireless Body Area Networks

WBANs (Wireless Body Area Networks) are frequently depicted as a paradigm shift in healthcare from traditional to modern E-Healthcare. The vitals of the patient signs by the sensors are highly sensitive, secret, and vulnerable to numerous adversarial attacks. Since WBANs is a real-world application of the healthcare system, it’s vital to ensure that the data acquired by the WBANs sensors is secure and not accessible to unauthorized parties or security hazards. As a result, effective signcryption security solutions are required for the WBANs’ success and widespread use. Over the last two decades, researchers have proposed a slew of signcryption security solutions to achieve this goal. The lack of a clear and unified study in terms of signcryption solutions can offer a bird’s eye view of WBANs. Based on the most recent signcryption papers, we analyzed WBAN’s communication architecture, security requirements, and the primary problems in WBANs to meet the aforementioned objectives. This survey also includes the most up to date signcryption security techniques in WBANs environments. By identifying and comparing all available signcryption techniques in the WBANs sector, the study will aid the academic community in understanding security problems and causes. The goal of this survey is to provide a comparative review of the existing signcryption security solutions and to analyze the previously indicated solution given for WBANs. A multi-criteria decision-making approach is used for a comparative examination of the existing signcryption solutions. Furthermore, the survey also highlights some of the public research issues that researchers must face to develop the security features of WBANs.publishedVersio

Effectively Predicting the Presence of Coronary Heart Disease Using Machine Learning Classifiers

Coronary heart disease is one of the major causes of deaths around the globe. Predicating a heart disease is one of the most challenging tasks in the field of clinical data analysis. Machine learning (ML) is useful in diagnostic assistance in terms of decision making and prediction on the basis of the data produced by healthcare sector globally. We have also perceived ML techniques employed in the medical field of disease prediction. In this regard, numerous research studies have been shown on heart disease prediction using an ML classifier. In this paper, we used eleven ML classifiers to identify key features, which improved the predictability of heart disease. To introduce the prediction model, various feature combinations and well-known classification algorithms were used. We achieved 95% accuracy with gradient boosted trees and multilayer perceptron in the heart disease prediction model. The Random Forest gives a better performance level in heart disease prediction, with an accuracy level of 96%.publishedVersio

Efficient and Secure Key Management and Authentication Scheme for WBSNs Using CP-ABE and Consortium Blockchain

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Association between environmental tobacco smoke and dental caries amongst 5-14 years old children in Karachi, Pakistan.

Objective:To determine the association between environmental tobacco smoke and dental caries.Methods:This cross-sectional study was conducted in peri-urban and urban areas of Karachi, from February to August 2014, and comprised children aged 5-14 years. A pre-coded questionnaire for environmental tobacco smoke and food frequency questionnaire for dietary habits were used. Dental examination of children was done to detect caries. Cox-proportional hazard algorithm was used to measure the association of environmental tobacco smoke with dental caries at multivariable level. STATA version 12.0 was used for statistical analysis.Result:Of the 500 children, 250(50%) each were from peri-urban and urban localities. The prevalence of dental caries was 336(67.2%).Family members of 154(30.8%) participants reported smoking. After adjusting for junk food intake, in-between meals, age, plaque index, dental visits and socio-economic status, the association between environmental tobacco smoke and dental caries remained statistically significant (p30 minutes of environmental tobacco smoke exposure, respectively.Conclusions:Environmental tobacco smoke was found to be associated with dental caries

Modelling the determinants and Sustainability of Current Account of Pakistan

The study investigated the determinants of the current account deficit from 1976 to 2020 for the economy of Pakistan, and its sustainability. The persistent deficit is necessary to be sustainable if it will be paid off shortly otherwise it will pile up external debt. The conventional methodology concluded that current account deficit (CAD) of Pakistan is unsustainable, albeit one measure suggests sustainability. There is cointegration among variables and domestic saving, external debt, fiscal deficit and trade deficit has positive whereas exchange rate and worker’s remittances have a negative relation with the current account, all the results are significant. The negative sign of the error correction term confirms restoration of equilibrium and it is also significant. Bidirectional causality is reported between the worker’s remittances, exchange rate and external debt with CAD. Unidirectional causality is seen from CAD to trade deficit and fiscal deficit. The diagnostic tests of the model confirm robustness. The government should favour an investment-friendly environment to increase economic activity in the country besides improving domestic savings and reducing the external deficit

Blockchain-Based Land Registration System: A Conceptual Framework

Land registration authorities are frequently held accountable for the alleged mismanagement and manipulation of land records in various countries. Pakistan’s property records are especially vulnerable to falsification and corruption because of the country’s poverty. Different parties therefore claim varying degrees of authority over a specific piece of land. Given the fact that this data has been consolidated, it has become significantly more vulnerable to security threats. The goal of decentralized system research has been to increase the reliability of these systems. In order to fix the flaws of centralized systems, blockchain-based decentralized systems are currently in development. By using significant land record registration models as the basis for this research, we hope to create a proof-of-concept system or framework for future use. Pakistan’s land registration agency will benefit from our proposed conceptual framework. For the Pakistani government to implement a decentralized land record registry system, we propose a conceptual framework that outlines the essential components.publishedVersio