Modelling of incident sound wave propagation around sound barriers using cellular automata

In the present study, acoustic wave propagation in the field including sound isolation panel is simulated using Cellular Automata (CA). CA is a discrete system which consists of finite state variables, arranged on a uniform grid. CA dynamics is described by a local interaction rule which is used for computation of new state of each cell from the present state at every time step. In this study a sound field is modeled using CA where the sound isolation panel exists and the numerical simulation results are evaluated quantitatively by the insertion loss. The results showed good correspondence with analytical solutions. © 2012 Springer-Verlag Berlin Heidelberg

Improvements in the acoustical modelling of traffic noise prediction: theoretical and experimental results

2009 - 2010Traffic acoustical noise is one of the most important component of the urban environmental pollution in densely populated areas all over the world. A very recent ACI-Censis study [1] on Italian urban areas shows that car is the favorite mean of transportation for 90% of population. In particular, this study shows that during years ranging from 2000 to 2007, the number of circulating vehicles is grown of 14.5%. To this growth did not always correspond an improvement of national street network. This problem can be evidenced by the high growth of the traffic charge on urban, sub-urban and extra-urban roads, with a clear impact on costs, security and environment, even in term of acoustical noise. A similar tendency can be observed in the framework of many european countries. Traffic noise affects areas surrounding roads especially when high traffic load and high speed conditions occur and can lead to a degradation of the quality of life in residential areas. The impact of noise on mental and physical health and on daily activities has been widely documented in the scientific literature [2, 3, 4]. In particular a continuous exposure to acoustical noise may affect sleep and/or conversation, may lead to perception of annoyance, may cause hearing loss, cardiovascular problems etc. As a consequence, during last years, a large number of anti-noise laws, ordinances and regulations were decreed by many national governments and international institutions. Looking to Italy, it is the D.P.C.M. 01.03.1991 [5] which regulates noise pollution matters, giving the main acoustical elements definitions such as maximum limit of noise exposure in inner and external environment, acoustic zoning criteria, etc. Then the Framework Law n. 447/1995 has defined a general policy on the noise pollution that has been implemented in different decrees and regulations. Among these, one of the most interesting is the D.M.A. 16.03.1998 ”Noise pollution detection and measurement method” (Tecniche di rilevamento e di misurazione dell’inquinamento acustico) which deals with the vehicular and railway noise detection procedure. Moreover the D.Lgs 194/2005 (Attuazione della direttiva 2002/49/CE relativa alla determinazione e alla gestione del rumore ambientale) establishes the method to set the acoustic indicator for the different kind of noise sources such as vehicular traffic. In this Ph.D. thesis our aim is to improve the current prediction tools for traffic noise prediction in non trivial situations such as traffic lights, traffic jam, intersections etc., accounting some aspects of traffic dynamics by the use of traffic models (TM), i.e. following the leader model and Cellular Automata. This thesis is organized as follows. In the first chapter we briefly discuss the main features of sound and noise propagation. In the second chapter we focus our attention on vehicle noise emission and existing traffic noise models (TNM) while in the third we present a new noise prediction procedure: GERIAN2009. In chapter four some general features of physics of road traffic and transportation are discussed. In the last three chapters we propose an integration of traffic noise model and traffic dynamic model in the ”following the leader” and Cellular Automata (CA) framework, with a particular attention on road’s intersection issue. [edited by author]IX n.s

The use of GIS for the development of a fully embedded predictive fire model

Fire is very important for maintaining balance in the ecosystems and is used by fire management across the world to regulate growth of vegetation in natural conservation areas. However, improper management of fire may lead to hazardous behaviour. Fire modelling tools are implemented to provide fire managers with a platform to test and plan fire management activities. Fire modelling occurs in two parts: fire behaviour models and fire spread models, where fire behaviour models account for the behaviour of fires that is used in fire spread models to model the propagation of a fire event. Since fire is a worldwide phenomenon a number of fire modelling approaches have been developed across the world. Most existing fire models only model either fire behaviour or fire spread, but not both, hence full integration of fire models into GIS is not completely implemented. Full integration of environmental modelling in GIS refers to the case where an environmental model such as a fire model is implemented within a GIS environment, without requiring any transfer of data from other external environments. Most existing GIS based fire spread models account for fire propagation in the direction of prevailing winds (or defined fire channels) as opposed to full fire spread in all directions. The purpose of this study is to illustrate the role of GIS in fire management through the development of a fully integrated, predictive, wind driven, surface fire model. The fire model developed in this study models both the risk of fire occurring (fire behaviour model), and the propagation of a fire in case of an ignition incident (fire spread model), hence full integration of fire modelling in a GIS environment. The fire behaviour model is based on prevailing meteorological conditions, the type of vegetation in an area, and the topography. The spread of a fire in this model is determined by the transfer of heat energy and rate of spread of fire, and is developed based on the Cellular Automata (CA) modelling approach. This model considers the spread of fire in all directions instead of the forward wind direction only as is the case in most fire spread models. The fire behaviour model calculates fire intensity and rate of spread which are used in the fire spread model, hence demonstrating the full integration of fire modelling in GIS. No external data exchange with the model occurs except for acquisition of input data such as measured values of environmental conditions. v This cellular automata based fire spread model is developed in the ArcGIS ModelBuilder geoprocessing environment, and requires the development of a custom geoprocessing function tool to facilitate the fast and effective performance of the model. The test study area used in this research is the Kruger National Park because of frequent fire activity that occurs in the park, as a result of management activities and accidental fires, and also because these fires are recorded by park fire ecologists. Validation of the model is achieved by comparison of simulated fire areas after a certain period of time with known location of the fire at that particular time. This is achieved by the mapping of fire scars and active fire areas acquired from MODIS Terra and Aqua images, fire scars are also acquired from the Kruger National Park Scientific Services. Upon evaluation, the results of the fire model show successful simulation of fire area with respect to time. The implementation of the model within the ArcGIS environment is also performed successfully. The study thus concludes that GIS can be successfully used for the development of a fully integrated (embedded) fire model

Epidemiological cellular automata: a case study involving AIDS

The spread of disease is a major health concern in many parts of the world. In the absence of vaccines and treatments, the only method to stop the spread of disease is to control population movements. Human mobility is one of the causes of the geographical spread of emergent human infectious diseases and plays a key role in human-mediated bio-invasion, the dominant factor in the global biodiversity crisis. One of the most serious emergent infectious diseases in the last 30 years or so is AIDS (acquired immunodeficiency syndrome), where multiple pathogen species infect a human body. HIV/AIDS is now considered much more commonplace than previously thought. AIDS leads to interaction effects between the pathogens that may alter previously understood patterns of disease spread. There has been longstanding interest in how to model population movements in order to find optimal control strategies for a particular disease. The simulation models proposed here use cellular automata based on sound mathematical principles and epidemiological theory to model HIV/AIDS to provide a suitable framework to study the spatial spread of disease in different scenarios. This work investigates how probabilistic parameters affect the model in terms of time, location, gender, age and subgroups of the population. The cellular automaton modelling approach is used to forecast numbers of cases in different subgroups. An approach using wavelet transforms analysis is illustrated to understand the impact of delay on the spread of infectious disease. The results confirm that the higher the frequency, then the slower the spread of disease and vice versa. The thesis concludes with showing how co-infection can be modelled in future work on a theoretical base

Fire performance of residential shipping containers designed with a shaft wall system

seven story building made of shipping containers is planned to be built in Barcelona, Spain. This study mainly aimed to evaluate the fire performance of one of these residential shipping containers whose walls and ceiling will have a shaft wall system installed. The default assembly consisted of three fire resistant gypsum boards for vertical panels and a mineral wool layer within the framing system. This work aimed to assess if system variants (e.g. less gypsum boards, no mineral wool layer) could still be adequate considering fire resistance purposes. To determine if steel temperatures would attain a predetermined temperature of 300-350ºC (a temperature value above which mechanical properties of steel start to change significantly) the temperature evolution within the shaft wall system and the corrugated steel profile of the container was analysed under different fire conditions. Diamonds simulator (v. 2020; Buildsoft) was used to perform the heat transfer analysis from the inside surface of the container (where the fire source was present) and within the shaft wall and the corrugated profile. To do so gas temperatures near the walls and the ceiling were required, so these temperatures were obtained from two sources: (1) The standard fire curve ISO834; (2) CFD simulations performed using the Fire Dynamics Simulator (FDS). Post-flashover fire scenarios were modelled in FDS taking into account the type of fuel present in residential buildings according to international standards. The results obtained indicate that temperatures lower than 350ºC were attained on the ribbed steel sheet under all the tested heat exposure conditions. When changing the assembly by removing the mineral wool layer, fire resistance was found to still be adequate. Therefore, under the tested conditions, the structural response of the containers would comply with fire protection standards, even in the case where insulation was reduced.Postprint (published version

Mutual information for the detection of crush conditions

Fatal crush conditions occur in crowds with tragic frequency. Event organizers and architects are often criticised for failing to consider the causes and implications of crush conditions, but the reality is that the prediction of such conditions o ers signi cant challenges. This thesis investigates the use of crush metrics in simulation environments, which can be used to help quantify the danger of crush conditions forming during real life evacuations. An investigation is carried out in the use of computer models for the purpose of simulating building evacuation. From this review we identify the most suitable methodologies for modelling crowd behaviour, and we detail the speci c areas of functionality which must be in place before modellers can incorporate crush analysis into an evacuation simulation. We nd that full treatment of physical force within crowd simulations is precise but computationally expensive; the more common method, human interpretation of simulation output, is computationally \cheap" but subjective and timeconsuming. A technique which admits a low computational cost alternative to the explicit modelling of physical force, yet still o ers a quantitative metric for the level of force present during an in silico evacuation is proposed. This technique and the precise manner in which we apply it to the problem of crush detection is shown and we present the results of initial experiments. To further test the ability of our technique to identify dangerous evacuation conditions, we recreate a well-known historical evacuation. Results of these experiments show that we do o er an e ective and e cient route towards the low cost automatic detection of crush, and an alternative approach to traditional methods

Unconventional Computing and Music: An Investigation into Harnessing Physarum polycephalum

This thesis presents an investigation into developing musical systems with an Unconventional Computing substrate. Computer musicians have found it difficult to access the field of Unconventional Computing, which is likely due to its resource-intensive and complex nature. However, ongoing research is establishing the myxomycete Physarum polycephalum as a universally-accessible and versatile biological computing substrate. As such, the organism is a potential gateway for computer musicians to begin experimenting with aspects of Unconventional Computing. Physarum polycephalum, in its vegetative plasmodium form, is an amorphous unicellular organism that can respond with natural parallelism to the environmental conditions that surround it. This thesis explores the challenges and opportunities related to developing musical systems with Physarum polycephalum. As this area of inquiry is in its infancy, the research took inspiration from a common approach in Unconventional Computing: a journey of exploration and discovery. This journey consisted of a selection of waypoints that provided direction while allowing the research to explore applications of Physarum polycephalum in order to establish how it may be useful in Computer Music. These waypoints guided the research from adapting established prototypes for musical application to developing purpose-made musical demonstrators for use outside of the laboratory. Thus, the thesis reports on a series of Computer Music systems that explore one or more features of Physarum polycephalum's behaviour and physiology. First, the text presents an approach to algorithmic composition that exploits the organism's ability to form and reconfigure graph-like structures. Next, the thesis reports on systems that harness the plasmodium's electrical potential oscillations for sound synthesis and compositional tools. Finally, the thesis presents musical devices that encompass living plasmodium as electrical components. Where applicable, the thesis includes artefacts from demonstrations of these systems, some of which were developed in collaboration with a composer. The findings from this journey demonstrate that Physarum polycephalum is an appropriate substrate for computer musicians wanting to explore Unconventional Computing approaches creatively. Although Physarum polycephalum is relatively robust as a biological substrate, several obstacles arose during this project. This research addressed such obstacles by reviewing and selecting approaches that maintained the organism's accessibility to computer musicians. As a result, the work suggests methods for developing systems with the organism that are practical for the average music technologist and also beneficial to the wider group of scientists investigating Physarum polycephalum for other purposes.Plymouth University HumPA Studentshi

Cellular Metals: Fabrication, Properties and Applications

Cellular solids and porous metals have become some of the most promising lightweight multifunctional materials due to their superior combination of advanced properties mainly derived from their base material and cellular structure. They are used in a wide range of commercial, biomedical, industrial, and military applications. In contrast to other cellular materials, cellular metals are non-flammable, recyclable, extremely tough, and chemically stable and are excellent energy absorbers. The manuscripts of this Special Issue provide a representative insight into the recent developments in this field, covering topics related to manufacturing, characterization, properties, specific challenges in transportation, and the description of structural features. For example, a presented strategy for the strengthening of Al-alloy foams is the addition of alloying elements (e.g., magnesium) into the metal bulk matrix to promote the formation of intermetallics (e.g., precipitation hardening). The incorporation of micro-sized and nano-sized reinforcement elements (e.g., carbon nanotubes and graphene oxide) into the metal bulk matrix to enhance the performance of the ductile metal is presented. New bioinspired cellular materials, such as nanocomposite foams, lattice materials, and hybrid foams and structures are also discussed (e.g., filled hollow structures, metal-polymer hybrid cellular structures)