Topics in complex systems

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Fundamental laws of physics, although successful in explaining many phenomena observed in nature and society, cannot account for the behaviour of complex, non-Hamiltonian systems. Much effort has been devoted to better understanding the topological properties of these systems. Neither ordered nor disordered, these systems of high variability are found in many areas of science. Studies on sandpiles, earthquakes and lattice gases have all yielded evidence of complexity in the form of power law distributions. This scalefree characteristic is believed to be the hall-mark of complexity known as self-organised criticality. Systems in the self-organised critical state regulate themselves and are resistant to error and attacks. The aim of this thesis is to further current knowledge of complex systems by proposing and analysing three models of real systems. Statistical mechanics and numerical simulations are used to analyse these models. The first model mimics herd behaviour in social groups and encompasses growth and addition. It has been found that when the growth rate is fast enough, the group size distribution conforms to a power law. When the growth rate is slow, the system runs out of free agents in finite time. The second model aims to capture the basic empirical measurements from hospital waiting lists. This model illustrates how the power law distributions found in empirical studies might arise, but also indicates that these distributions are unlikely to be caused by the preferential behaviour of patients or physicians. The third model is a salary comparison model; the salary distributions of most of its variants are power laws. Both mean field and 1-d versions of the model are analysed, and differences between the two versions are identified by looking at the mean absolute difference between the salaries in each version

Recent observation and measurements of diboson processes from the ATLAS experiment

This review covers results at a centre-of-mass energy of $\sqrt{s}=13$ TeV from the ATLAS experiment that have been published, or submitted for publication, up to April 2020. It summarizes results on the inclusive production cross-section measurements of boson pairs and of the electroweak production of diboson in association with two jets. The measurements either use the full integrated luminosity of 139 $\text{fb}^\text{-1}$ collected by the ATLAS detector at the LHC from 2015 to 2018, or a partial dataset of 36 $\text{fb}^\text{-1}$. The inclusive production rates of diboson are studied to high precision. These measurements provide stringent tests of the electroweak sector of the Standard Model and allow search for new physics via anomalous triple and quartic gauge boson couplings

Sudden cardiac death

Sudden cardiac death (SCD) continues to be a major health issue in many countries including Malaysia due to its large magnitude in all-cause mortality as well as the emotional and socioeconomic impact of the deceased leaving the love ones behind in an abrupt manner. Data in Malaysia shows that the majority of sudden natural deaths are due to sudden cardiac death and are in the productive age group of 41 to 50 years. A study in Germany pointed out that about 90% people who died of SCD actually had warning signs such as chest pain, breathlessness, nausea, vomiting, dizziness and fainting before they collapsed. The majority belonged to the high-risk group for SCD having had previous medical histories including coronary artery disease, cardiomyopathies, valvular heart disease, congenital heart disease, underlying electrophysiological abnormalities or are taking drugs which are capable of provoking ventricular tachyarrhythmias. The key step is to define a sequence of risk stratifiers that will identify patients who are at risk but in whom implantation of expensive devices will be cost-effective. Amongst the investigative tools proven to be helpful to achieve this are ECG screening for left ventricular hypertrophy, increased QRS width, T-wave alternans, heart rate variability, baroreceptor responsiveness, QT dispersion, and T-wave heterogeneity; Holter monitoring to demonstrate ventricular arrhythmias; and stress test in identifying ischaemia. Prompt action is crucial since restoring circulation as fast as possible improves the chances of survival. Family members and caregivers of people with heart disease and at increased risk should be trained to recognise symptoms and perform cardiopulmonary resuscitation (CPR) to reduce the likelihood of death from cardiac arrest. Training and prevention efforts should focus on how to recognise the emergency, CPR training, and automated external defibrillator (AED) use. An implantable cardioverter-defibrillator (ICD) is the preferred therapeutic modality in most survivors of SCD. The incidence of SCD can be reduced by improving the current situation through selection of high risk groups for initiation of therapies, education to the public on the awareness of early warning symptoms and early emergency management that should be readily available in the communit

Study On Various Adhesion Mechanism For A Wall Climbing Robot

A wall-climbing robot has provoked high attention worldwide ever since it was born in 1960’s. The main function of a wall-climbing robot to survey human being in highly hazardous and dangerous working environment. The aim of this study is to design and develop adhesion mechanism for a wall climbing robot that is adaptable to the various wall surface. Study of various adhesion mechanism and the design structure on wall climbing robot is required in order to understand the concept and function of a wall climbing robot. The adhesion mechanism used in this wall climbing robot is pushing mechanism with propeller and magnetic attachment system on wheel design to allow the robot stick and move against the vertical wall surface. High torque motor that controlled by the motor-driven which attach with Arduino UNO is used to cover the friction and gravitational force when the robot is moving. With the aid of the Arduino IDE software, the algorithm is built up and the theoretical result is generated to verify the force needed to support the robot move on the vertical wall surface. However, the robot is able to attach on the vertical surface but unable to move against the vertical surface of the ferromagnetic cupboard. The failure analysis is described as power loss and the thrust force generated not strong enough to support the robot move against the vertical surface. Lastly, the concept of adhesion mechanism is work but there is some improvement that can be considered to improve the stability and performance of wall climbing robot

The feasibility of quarry dust powder suspension for surface modification of tungsten carbide cobalt

Among composite materials, tungsten carbide cobalt (WC-Co) has a huge application in the industrial sector, especially in the mould and die industry. However, those mould and die material will wear out after some service time. Considering the hardness and high cost of WC-Co, most industries decided to dispose and buy new moulds and dies rather than repair them after wear. Thus, the surface modification of WC-Co is necessary to increase its lifespan and service time. In this study, the surface modification of WC-Co was done by using the electrical discharge coating (EDC) with quarry dust suspension. Before the experiment, the characteristic of quarry dust was investigated, which included the element composition and chemical compound, particle size and surface morphology. A Sodick AQ35L die-sinker EDM machine was used to conduct the EDC process. The effect of coating parameters (peak current (Ip) and pulse on time (Ton)) on the surface roughness, Vickers micro-hardness and layer thickness were investigated. A Respond Surface Methodology (RSM) matrix created by Minitab software was used to determine the parameter effects and the optimum parameters of this research. The quarry dust in different concentrations were compared and their effect to the characteristics of coated surface were also determined. The results show that the optimum parameters to achieve a hard surface, thick coating layer and low value of surface roughness were found to be at Ip = 4 A and Ton = 341 μs. Besides, the best coated surface finish without the micropores and microcracks can be obtained by using 10 g/l of quarry dust powder. Coating layer thickness was strongly affected by the quarry dust concentration. These results demonstrated the capability of reusing and recycling quarry dust as an environmental friendly coating material for surface modification of tungsten carbide cobalt (WC-Co) by using EDC process

Influence of intercalation-exfoliation-reduction technique towards the physico-chemical of VPO catalysts

Four VPO catalysts were synthesized through intercalation and exfoliation in various alcohols and subsequent reduction of the exfoliated VOPO4 sheets with various alcohols to produce VOHPO40.5H2O. The resulting VOHPO40.5H2O that undergoes the intercalation-exfoliation-reduction (IER) process will be further activated into VPO catalysts, and addition of 1 mole Bi(NO3)35H2O in the first stage of this experiment has also being investigated. The synthesized materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and temperature-programmed reduction (TPR) in H2. Catalytic evaluation of the IER-treated and Bi-doped VPO catalysts was also studied on microreactor. The VPO catalyst produced through IER using 2-butanol and ethanol with addition of Bi, IERC(2Bu-Et)RBi1, gave the highest MA selectivity due to reactive O 2- species released from the additional crystalline V 5+ phase formed by doping 1 bismuth as promoter (O 2-V 5+ pair) at relative lower temperature. Nevertheless, the VPO catalyst produced through IER using isobutanol, IERC(isoBu), gave the highest activity due to high amount of reactive O - species released from V 4+ phase (O - V 4+ pair) whereby the IERC(isoBu) catalyst synthesized consists of high percentage of V 4+ (93)

Capital Punishment in Singapore: A Critical Analysis of State Justifications From 2004 to 2018

This article examines state justifications for capital punishment in Singapore. Singapore is a unique case study because capital punishment has largely been legitimised and justified by state officials. It illustrates how Singapore justifies capital punishment by analysing official discourse. Discussion will focus on the government’s narrative on capital punishment, which has been primarily directed against drug trafficking. Discussion will focus on Singapore’s death penalty regime and associated official discourse that seeks to justify state power to exercise such penalties, rather than the ethics and proportionality of capital punishment towards drug-related crimes. Critical analysis from a criminological perspective adds to the growing body of literature that seeks to conceptualise social and political phenomena in South-East Asia. &nbsp

Internet-Based Advisory System for Automotive Spare Parts Industry

The purpose of this project is to design an e-commerce website, suitable for the current needs in automobile spare parts industry. A current survey is done on some local and international automobile spare parts websites. The review shows that this websites have some weakness and limitations. Based on the limitations, this system is designed to overcome the problems and try to satisfy user needs. The special element about this system is that it has an advisory system and portal link. This advisory system is able to recommend suitable spare parts for user. The website will then link user in the relevant company to buy the recommended spare parts. Finally, this project has recommended some future design and considerations to further enhance the development of future project

Relationship of SARS-CoV to other pathogenic RNA viruses explored by tetranucleotide usage profiling

BACKGROUND: The exact origin of the cause of the Severe Acute Respiratory Syndrome (SARS) is still an open question. The genomic sequence relationship of SARS-CoV with 30 different single-stranded RNA (ssRNA) viruses of various families was studied using two non-standard approaches. Both approaches began with the vectorial profiling of the tetra-nucleotide usage pattern V for each virus. In approach one, a distance measure of a vector V, based on correlation coefficient was devised to construct a relationship tree by the neighbor-joining algorithm. In approach two, a multivariate factor analysis was performed to derive the embedded tetra-nucleotide usage patterns. These patterns were subsequently used to classify the selected viruses. RESULTS: Both approaches yielded relationship outcomes that are consistent with the known virus classification. They also indicated that the genome of RNA viruses from the same family conform to a specific pattern of word usage. Based on the correlation of the overall tetra-nucleotide usage patterns, the Transmissible Gastroenteritis Virus (TGV) and the Feline CoronaVirus (FCoV) are closest to SARS-CoV. Surprisingly also, the RNA viruses that do not go through a DNA stage displayed a remarkable discrimination against the CpG and UpA di-nucleotide (z = -77.31, -52.48 respectively) and selection for UpG and CpA (z = 65.79,49.99 respectively). Potential factors influencing these biases are discussed. CONCLUSION: The study of genomic word usage is a powerful method to classify RNA viruses. The congruence of the relationship outcomes with the known classification indicates that there exist phylogenetic signals in the tetra-nucleotide usage patterns, that is most prominent in the replicase open reading frames

Effect of calcination temperature on the characteristics of MoV oxides prepared via reflux method

In this study, MoV mixed oxides with a molar ratio of 10:3 were prepared by reflux method. The samples were subjected to various calcination temperatures in order to investigate the physicochemical properties of the oxide affected by the parameter. Samples were characterised by XRD, TG/DTA, BET surface area, SEM and TPR. By imposing various calcination temperatures, phase evolutions were observed. However, these changes do not significantly affect the morphology, surface area, particle size and reducibility of the oxide. Still, the best calcination temperature can be chosen to arrive at the effective catalyst necessary for the desired catalytic reaction