Characterising a Design Fire for a Deliberately Lit Fire Scenario

Deliberately lit fires make up over 15% of all fires in New Zealand buildings yet they are typically omitted from the design brief for fire engineering purposes. This report examines where deliberately lit fires should be included as part of the fire engineering design by examination of all deliberately lit fires recorded in the New Zealand Fire Incident Reporting System (NZ FIRS) between the years 1996 and 2006. The main types of buildings identified where consideration of deliberately lit fires within the design would provide benefits are: · Prisons · Psychiatric institutions · Schools · Crowd activities · Attached accommodation The report also examined what is required to include deliberately lit fires as part of the design process. Based on an analysis of the fire incident statistics, the majority of deliberately lit fires are the result of unplanned activities and existing design fires will be adequate. Two critical fire scenarios were identified as exceeding these requirements, the ignition of multiple fires and the use of accelerants. Greater life safety benefits are obtained by considering accelerants. In the case of multiple fires, each fire is likely to be within the capabilities of a fire engineered building however a number of such fires may overwhelm the fire protection features of a building. A number of issues for the fire engineer to consider are briefly discussed. In the case of accelerants, a number of experiments were completed to characterise the heat release rate and species production of a Molotov cocktail based on the fuel volume used. A second round of experiments extended this work by examining the scenario where a Molotov cocktail containing 1000 milliliters of petrol was deployed within a stairwell

A comparison of component-based software engineering and model-driven development from the ProCom perspective

Component-based software engineering (CBSE) and model-driven development (MDD) are two approaches for handling software development complexity. In essence, while CBSE focuses on the construction of systems from existing software modules called components; MDD promotes the usage of system models which after a series of transformations result with an implementation of the desired system. Even though they are different, MDD and CBSE are not mutually exclusive. However, there has not been any substantial research about what their similarities and differences are and how they can be combined. In this respect, the main goal of this thesis is to summarize the theoretical background of MDD and CBSE, and to propose and apply a systematic method for their comparison. The method takes into account the different effects that these development paradigms have on a wide range of development aspects. The comparison results are then summarized and analyzed. The thesis also enriches the theoretical discussion with a practical case study comparing CBSE and MDD with respect to ProCom, a component model designed for the development of component-based embedded systems in the vehicular-, automation- and telecommunication domains. The aforementioned comparison method is refined and applied for this purpose. The comparison results are again summarized, analyzed and proposals about future work on ProCom are made

Brokering techniques for managing three-tier applications in distributed cloud computing environments

© 2015 Dr. Nikolay GrozevCloud computing is a model of acquiring and using preconfigured IT resources on demand. Cloud providers build and maintain large data centres and lease their resources to customers in a pay-as-you-go manner. This enables organisations to focus on their core lines of business instead of building and managing in-house infrastructure. Such in-house IT facilities can often be either under or over utilised given dynamic and unpredictable workloads. The cloud model resolves this problem by allowing organisations to flexibly resize/scale their rented infrastructure in response to the demand. The confluence of these incentives has caused the recent widespread adoption of cloud services. However, cloud adoption has introduced challenges in terms of service unavailability, regulatory compliance, low network latency to end users, and vendor lock-in. These factors are of special importance for large scale interactive web-facing applications, which observe unpredictable workload spikes and need to serve users worldwide with low latency. The utilisation of multiple cloud sites (i.e. a Multi-Cloud) has emerged as a promising solution. Multi-Cloud approaches also facilitate cost reduction by taking advantage of the diverging prices in different cloud sites. The 3-Tier architectural model is the de-facto standard approach to build interactive web systems. It divides the application in three tiers: (i) presentation tier which implements the user interfaces, (ii) domain tier implementing the core business logic, and (iii) data tier managing the persistent storage. This logical division most often leads to deployment separation as well. This thesis investigates dynamic approaches for workload distribution and resource provisioning (a.k.a. brokering) of 3-Tier applications in a Multi-Cloud environment. It advances the field by making the following key contributions: 1. A performance model and a simulator for 3-Tier applications in one and multiple clouds. 2. A system architecture for brokering 3-Tier applications across clouds, which considers latency, availability, and regulatory requirements and minimises the overall operational costs. 3. An approach for Virtual Machine (VM) type selection that reduces the total cost within a cloud site. It uses online machine learning techniques to address the variability of both the application requirements and the capacity of the underlying resources. 4. A rule-based domain specific model for regulatory requirements, which can be interpreted by a rule inference engine. 5. Design and implementation of a workload redirection system that directs end users to the individual cloud sites in a Multi-Cloud environment

Performance Modelling and Simulation of Three-Tier Applications in Cloud and Multi-Cloud Environments

A significant number of Cloud applications follow the 3-tier architectural pattern. Many of them serve customers worldwide and must meet non-functional requirements such as reliability, responsiveness and Quality of Experience (QoE). Thus the flexibility and scalability offered by clouds make them a suitable deployment environment. Latest developments show that using multiple clouds can further increase an application’s reliability and user experience to a level that has not been achievable before. However, the research in scheduling and provisioning 3-tier applications in clouds and across clouds is still in its infancy. To foster the research efforts in the area, we propose an analytical performance model of 3-tier applications in Cloud and Multi-Cloud environments. It takes into account the performance of the persistent storage and the heterogeneity of cloud data centres in terms of Virtual Machine (VM) performance. Furthermore, it allows for modelling of heterogeneous workloads directed to different data centres. Based on our model, we have extended the CloudSim simulator, through which we validate the plausibility of our approach. The conducted experiments with the RUBiS workload show that the predicted performance characteristics by the simulation approximate well those of the modelled system

The Law of Parsimony and the Negative Charge of the Bubbles

Why the bubbles are negatively charged? This is almost 100 years old question, which many scientists have striven and still are striving to answer using the latest developments of the MD simulations and various physical analytical methods. We scrutinize with this paper the basic literature on this topic and conduct our own analysis. Following the philosophical law of parsimony: “Entities should not be multiplied without necessity”, we assume that the simplest explanation is the right one. It is well known that the negative change of the Gibbs free energy is a solid criterion for spontaneous process. Hence, we calculated the energies of adsorption of OH−, H3O+ and HCO3− ions on the air/water interface using the latest theoretical developments on the dispersion interaction of inorganic ions with the air/water interface. Thus, we established that the adsorption of OH− and HCO3− ions is energetically favorable, while the adsorption of H3O+ is energetically unfavorable. Moreover, we calculated the change of the entropy of these ions upon their transfer from the bulk to the air/water interface. Using the well-known formula ΔG = ΔH − TΔS, we established that the adsorption of OH− and HCO3− ions on the air/water interface decreases their Gibbs free energy. On the contrary, the adsorption of H3O+ ions on the air/water interface increases their Gibbs free energy. Thus, we established that both OH− and HCO3− ions adsorb on the air/water interface, while the H3O+ ions are repelled by the latter. Therefore, electrical double layer (EDL) is formed at the surface of the bubble–negatively charged adsorption layer of OH− and HCO3− ions and positively charged diffuse layer of H3O+ ions

Investigation of Interfacial Free Energy of Three-Phase Contact on a Glass Sphere in Case of Cationic-Anionic Surfactant Aqueous Mixtures

The wetting of adsorbed surfactants solids is important for various technological applications in particular for the process of foam flotation. The present work aims at calculating the surface tensions of the three phase interfaces at different surfactant concentrations using the Girifalco and Good method. For this purpose, the surface tension and contact angle vs. surfactant concentration of the test substances amines and sulfonates and their mixture were measured for liquid–air interface. Calculated surface tension of solid–air interface vs. concentration for C10 amine and mixed systems are close to those for the liquid–air surface, but are slightly lower. In the case of mixed systems, the graph has a specific structure similar to that of liquid–air surface dependence. In contrast to the solid–air interface results, the solid–liquid surface tension values are significantly lower. In case of the mixed surfactant systems, C10amine/C10 sulfonate, a synergetic effect on the surface tension is observed. The specific behavior of the mixed systems is interpreted with the emergence of aggregates consisting of the anionic and cationic surfactants. It is shown that in the whole area of concentrations complete wetting does not occur

Electrostatic Forces in Control of the Foamability of Nonionic Surfactant

Can the DLVO theory predict the foamability of flotation frothers as MIBC (methyl isobutyl carbinol)? The flotation froth is a multi-bubble system, in which the bubbles collide, thus either coalescing or rebounding. This scenario is driven by the hydrodynamic push force, pressing the bubbles towards each other, the electrostatic and van der Waals forces between the bubbles, and the occurrence of the precipitation of the dissolved air between the bubbles. We studied the foamability of 20 ppm MIBC at constant ionic strength I = 7.5 × 10−4 mol/L at different pH values in the absence and presence of modified silica particles, which were positively charged, thus covering the negatively charged bubbles. Hence, we observed an increase in the foamability with the increase in the pH value until pH = 8.3, beyond which it decreased. The electrostatic repulsion between the bubbles increased with the increase in the pH value, which caused the electrostatic stabilization of the froth and subsequently an increase in the foamability. The presence of the particles covering the bubbles boosted the foamability also due to the steric repulsion between the bubbles. The decrease in the foamability at pH > 8.3 can be explained by the fact that, under such conditions, the solubility of carbon dioxide vanished, thus making the aqueous solution supersaturated with carbon dioxide. This caused the precipitation of the latter and the emergence of microbubbles, which usually make the bubbles coalesce. Of course, our explanation remains a hypothesis

Comparative Corrosion Characterization of Hybrid Zinc Coatings in Cl−-Containing Medium and Artificial Sea Water

The presented investigations demonstrate the corrosion behavior and protective ability of hybrid zinc coatings specially designed for combined protection of low-carbon steel from localized corrosion and biofouling. Polymer-modified copper oxide (CuO) nanoparticles as widely used classic biocide are applied for this purpose, being simultaneously electrodeposited with zinc from electrolytic bath. The corrosion behavior of the hybrid coatings is evaluated in a model corrosive medium of 5% NaCl solution and in artificial sea water (ASW). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) are used to characterize the surface morphology of pure and hybrid zinc coatings. Contact angle measurements are realized with an aim to determine the hydrophobicity of the surface. X-ray photoelectron spectroscopy (XPS) is applied for evaluation of the chemical composition of the surface products appearing as a result of the corrosion treatment. Potentiodynamic polarization (PDP) curves and polarization resistance (Rp) measurements are used to estimate the protective characteristics in both model corrosive media. The results obtained for the hybrid coatings are compared with the corrosion characteristics of ordinary zinc coating with the same thickness. It was found that the hybrid coating improves the anticorrosion behavior of low-carbon steel during the time interval of 35 days and at conditions of external polarization. The tests demonstrate much larger corrosion resistance of the hybrid coating in ASW compared to 5% NaCl solution. The obtained results indicated that the proposed hybrid zinc coating has a potential for antifouling application in marine environment