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The rate of destruction of 18F via the 18F + p reactions is of importance in both novae and X-ray burster explosive scenarios. The rate of the competing destructive reactions, 18F(p,γ)19Ne and 18F(p,α)15O, depend upon the level structure of the compound nucleus 19Ne. The first experiment in this thesis examines the level structure of 19Ne about the 18F + p threshold via elastic 15O(α,α)15O scattering. The experiment was performed at the CRC Louvain-la-Neuve. A radioactive 15O beam bombarded a thick 4He gaseous target with elastically scattered alpha particles detected using segmented silicon detectors. An R-matrix approach was used to analyse the data and extract the resonance parameters Er and Ѓα. Particular emphasis was placed on extracting information regarding the possible 3/2+ doublet, the parameters of which, to date, have been inferred from the mirror nucleus 19F. The nominal values for the doublet taken from the mirror are Er = 8 and 38 keV, with Ѓα = 0.27 and 1.3 keV respectively. Following this new analysis it has been found that the doublet straddles the threshold at Er = -22 and 3 keV, with Ѓα = 0.15 and 3.3 keV respectively. S-factor calculations and interference effects were also examined. The 18Ne(α,p)21Na reactions is believed to be a key process in X-ray bursters. It is thought to be a possible HCNO-breakout reaction; the mechanism responsible for producing energy to drive the X-ray burster. To date the reaction has been studied both directly and indirectly. The results from each previous experiment show su cient discrepancies to warrant a re-examination of the reaction rate. As such, the second experiment presented in this thesis revolves around a new direct measurement of 18Ne(α,p). The experiment was undertaken at the CRC Louvain-la-Neuve, where, a radioactive 18Ne beam impinged upon a thin gaseous 4He target. The beam energy was chosen to provide data points in common with previous experiments at Er = 1.7 and 2.5 MeV. Reaction protons were detected via a segmented silicon detector telescope system. The total cross section calculated at Er = 2.5 MeV is 1.22 0.151 mb. An upper limit for the cross-section of 0.0208 mb was evaluated at Er = 1.7 MeV.

While the data traffic has increased through the years, the average revenue per user (ARPU) remains flat. Thus, mobile network operators need to find a solution for how to support the growing amounts of traffic at fixed revenue per user. Similarly, the number of roaming users has increased, but according to recent European Union (EU) regulations, mobile network operators have to lower their charges for roaming to zero by June 2017. While this decrease in roaming charges will benefit European roaming users, mobile network operators have to cover their expenses for their own roaming subscribers, thus they have to find a way to lower their operational expenses (OPEX). Additionally, it is important for operators to consider how they might actually benefit from the removal of roaming charges. This project will focus on roaming in 4th generation (4G) mobile networks. A common roaming scenario would include three different networks: the Home Public Land Mobile Network (HPLMN) a transit network, and a Visited Public Land Mobile Network (VPLMN). Normally, both the signaling traffic and the media payloads traverse these networks, thus causing additional latencies and increasing OPEX. However, in recent years, a new mechanism, called local breakout (LBO), was introduced that can lower the costs of roaming and avoid unnecessary traffic while meeting a roaming user's needs. The goal of LBO is to decrease the operator's OPEX when supporting roaming subscribers. A secondary goal of LBO is to reduce the latencies experienced by roaming subscribers during their sessions. Achieving both of these goals will satisfy both operators and consumers. This thesis project analyzes Voice over Long Term Evolution roaming with the aim of presenting the various alternative architectures for Voice over LTE roaming, compare them in different scenarios, and evaluating them based on criteria defined during this project. The conclusion is that the best solution that is applicable to all the mobile network operators for all the possible roaming scenarios does not exist yet. The various VoLTE roaming architectures can be chosen by the mobile network providers according to their needs. / Datatrafiken har ökat genom åren men den genomsnittliga intäkten per användare (ARPU) är fortfarande oförändrad. Mobilnätsoperatörer bör hitta en lösning för att kunna stödja den växande mängden trafik på fasta intäkter per användare. Samtidigt har antalet roaming användare ökat. Enligt de senaste reglerna från Europeiska unionen (EU) måste mobiloperatörer sänka sina roamingkostnader till noll senast juni 2017. Denna minskning av roamingavgifterna kommer att gynna europeiska roaminganvändare, men mobilnätoperatörer måste samtidigt täcka sina kostnader för sina egna roamingabonnenter. Detta medför att mobilnätoperatörer måste hitta ett sätt att sänka sina driftskostnader (OPEX). Dessutom är det viktigt för operatörerna att fundera över hur de faktiskt kan utnyttja denna uteslutning av roamingavgifter. Detta projekt kommer att fokusera på roaming i den 4:e generationens (4G) mobila nät. Ett vanligt roaming scenario skulle omfatta tre olika nätverk: Home Public Land Mobile Network (HPLMN), transitnätverk, och en Visited Public Land Mobile Network (VPLMN). Vanligen är det både signaleringstrafik och media som passerar dessa nätverk. Det leder till ytterligare latenstider och ökande driftskostnader. Under de senaste åren har en ny mekanism som kallas för Local BreakOut (LBO) införts. Detta används för att sänka kostnaderna för roaming och undvika onödig trafik, samtidigt som den bemöter roaming användarens behov. Målet med LBO är att minska Operatörens OPEX när den stödjer roaming abonnenter. Ett sekundärt mål av LBO är att minska latensen för roamingabonnenter under sina sessioner. Uppnående av båda dessa mål kommer att tillfredsställa både operatörer och konsumenter. Detta examensarbete analyserar Voice over Long Term Evolution roaming i syfte att presentera de olika alternativa arkitekturer för Voice over LTE roaming, jämföra dem i olika scenarier, och utvärdera dem utifrån kriterier som fastställs under detta projekt.

<p>  </p> <p>The use of headed reinforcement in concrete has found an increasing interest in construction applications. From shear reinforcement in walls to longitudinal reinforcement in beams and columns, there is a growing need to understand the behavior of headed rebars. A headed rebar is a deformed bar with a head attached to its end and while similar anchorage devices such as headed studs and hooked rebars are well established in theory with design equations developed, headed reinforcement lack this level of knowledge and hence, their application in industry is limited.</p> <p>Current code provisions such as fib Model Code 2010 allow the design of headed rebars as (1) a hooked bar, (2) a headed stud, and (3) using experimental results. Moreover, ACI 318-19 only contains a design equation for the development length of headed rebars but not its capacity. While the literature has justified the approximation of the capacity of headed rebars with hooked bars through a multitude of studies comparing both anchorage devices. Such a justification is not well-founded for headed studs due to a scarcity of studies comparing headed rebars to headed studs. Moreover, there is a lack of design equations accurately predicting the behavior of headed rebars in several parameters. All these issues emanate from the complexity of headed rebars due to their joint mechanism of anchorage coming from both resistance along the rebar deformations and bearing on the head.</p> <p>This study aims to better understand the behavior of headed bars by numerically analyzing the influence of different parameters on their performance. Furthermore, direct comparisons are made between headed reinforcement, headed studs, and straight bars to segregate the effect of the bond along the shaft and the bearing at the head on the behavior of headed bars. </p> <p>The parameters included in this study are embedment depth, edge distance, and concrete compressive strength. The numerical models are verified using a 3D non-linear finite element software MASA (Macroscopic Space Analysis) which employs the microplane model with relaxed kinematic constraint as the constitutive laws of concrete. Two numerical approaches, which differ only in the interface properties between the head and concrete, are validated against experimental results before carrying out the parametric study. Several properties including head, concrete, and bond stresses, along with ultimate capacities and crack patterns are extracted from the models and analyzed. Moreover, the load-displacement graphs of headed rebars, studs, and straight rebars are compared and contrasted. Assessments and theories about the discrepancies between the behavior of headed studs and rebars are stipulated. Finally, potential methods for formulating design equations are proposed for future studies.</p>

Noise control in the heating, ventilation and air-conditioning (HVAC) systems is one of the critical design parameters in measuring the occupant comfort. The noise generated by air-handling units propagates through the ducts in the axial as well as transverse direction. Noise radiated in the transverse direction from the duct walls excited by the internal sound field is called the breakout noise. An analytical formulation has been developed in this thesis in order to predict the breakout noise by incorporating three-dimensional effects along with the acoustical and structural wave coupling phenomena. The first step in the breakout noise prediction is to calculate the interior acoustic response and flexural vibration displacement of the compliant walls. Dynamic interaction between the internal acoustic subsystem and flexible structural subsystem has been expressed in terms of the modal characteristics of the uncoupled response of the acoustic and structural sub-systems. Solutions of the inhomogeneous wave equation are rearranged in terms of impedance and mobility, and the equations describing the complete system are expressed in terms of matrices, which result in a compact matrix formulation. Examples of the formulation are a rectangular cavity with one flexible wall and a rectangular cavity with four-flexible walls. The formulation is modified to incorporate complex boundary conditions by means of appropriate Green’s functions. It is implemented for flexible wall duct using the modified cavity Green’s function. Another objective of the present investigation is to understand the coupling phenomenon and its effect on the compliant wall vibration displacement. The developed three-dimensional analytical analysis of the breakout noise is convenient to implement on the computer, and also to extend the sub-system level model to the system level model in order to analyze a complex acoustic-structural system for the breakout noise problem. The extent of coupling is calculated using a transfer factor based on the uncoupled natural frequencies of the acoustic and structural subsystems. It is observed from the free vibration analysis that a coupling between the cavity and the flexible panel exists in the vicinity of an uncoupled acoustic natural frequency. If a strong coupling occurs between an acoustic mode and a panel mode, then damping of structural subsystem would control it. The cavity volume changes stiffness of the panel, which in turn affects noise radiation in the stiffness-controlled region. The second step is to calculate the sound power radiated from complaint wall. The wall vibration velocity is a linear combination of the uncoupled flexural modes of the structural subsystem. It is substituted into the Rayleigh integral and Kirchhoff– Helmholtz (KH) integral formulation to predict the sound pressure radiated by the vibrating duct wall. The radiated sound power can be obtained by integrating the acoustic intensity over the surface of the flexible duct wall making use of appropriate expressions for radiation impedance. The radiation impedance terms involve a quadruple integral. Evaluation of this integral is quite complex and poses formidable computational challenges. These have been overcome by means of a co-ordinate transformation. Sound power radiation from flexible walls of the plenum and duct walls has been calculated using an equivalent plate model. Analytical results are corroborated with numerical models. The second part of thesis deals with a one-dimensional model to predict the breakout noise from a thin rectangular duct with different end conditions like anechoic termination, rigid-end termination, and the open-end termination. This model incorporates acoustic reflection effects in the duct internal sound field by using standing wave pattern by means of the transfer matrix approach. A one-dimensional prediction method based on the four-pole parameters has been developed to evaluate the lagged duct performance in terms of the breakout noise reduction. Radiation impedance of a duct is calculated by three different methods: (i) finite line source model (ii) finite cylinder model, and (iii) equivalent plate model based on fundamental bending mode of the duct. It is observed that the proposed model that uses the equivalent plate model for the lagged duct and the line source model for the bare duct is appropriate to predict the transverse insertion loss of the lagging, particularly at the lower frequencies that are of primary interest for reducing the breakout noise of rectangular ducts. The bare duct breakout noise results are compared with those of the corresponding 3-D analytical models. It shows that the one-dimensional model captures the overall mean pattern of breakout noise very well. The third part of the thesis examines the internal acoustic field and thence the transmission loss (TL) of a rectangular expansion chamber, the inlet and outlet of which are situated at arbitrary locations of the chamber; i.e., the sidewall or the face of the chamber. The four-pole parameters have been expressed in terms of an appropriate Green’s function of a rectangular cavity with homogeneous boundary conditions. A transfer matrix formulation has been developed for the yielding-wall rectangular chambers by considering structural-acoustic coupling. It may be combined readily with the transfer matrices of the other constituent elements upstream and downstream in order to compute the overall transmission loss or insertion loss. Wherever applicable, parametric studies have been conducted to evolve the design guidelines for minimizing the breakout noise from the HVAC ducts, plenums and cavities.

This thesis deals with creation of breakout prediction model implemented via artificial neural network in MATLAB, hence it contains theoretical description of artificial neural networks and also presents how the networks were used for the breakout prediction problem. In addition, models of heat conduction through the mold wall were created and used for generating neccesary data for proper training of artificial neural network. The thesis contains proper description of used numerical methods for solving the heat conduction problems. In the thesis are presented partial results and also results of testing created artificial neural network with usage of real data.

The use<b></b>of lightweight concrete in the concrete industry provides economical and practical advantages. Structural anchors are commonly used in the industry for various structural applications. In <i>ACI 318-19: Building Code Requirements for Structural Concrete and Commentary</i>, a modification factor, λ<i>_a</i>, is specified for the calculated design strengths of anchors installed in lightweight concrete that experience concrete or bond failure. The modification factor consists of the general lightweight concrete modification factor,λ, specified in the code multiplied by an additional reduction factor dependent on the anchor and failure type. For the concrete breakout strength of expansion and screw anchors in lightweight concrete, the value of λ<i>_a</i>is specified as 0.8λ. For the concrete breakout strength of cast-in anchors in lightweight concrete, the value of λ<i>_a</i>is 1.0λ. In both cases, however, the specified value of λ<i>_a</i>is based on limited test data. A research program was therefore conducted to provide the data needed for more appropriate lightweight modification factors. A primary objective of the research was to evaluate the concrete breakout strengths of cast-in, expansion, and screw anchors installed in lightweight concrete by conducting a systematic experimental program that included various types of lightweight concrete. More specifically, the experimental program included tension tests on torque-controlled expansion anchors, displacement-controlled expansion anchors, and screw anchors from four manufacturers in addition to tension tests on cast-in headed stud anchors. A total of seven concrete types were included in the research: one normalweight concrete mixture and six lightweight concrete mixtures. The lightweight concrete included sand-lightweight and all-lightweight mixtures composed ofexpanded shale, clay, and slate aggregates. The results of the experimental program are compared to limited data available from previous tension tests on anchors in lightweight concrete. Based on the results of the research, revised lightweight concrete modification factors for the concrete breakout design strengths of the anchor types included in the test program are provided.

Extreme hurricane events of the past decade are responsible for several drag embedment anchor (DEA) mooring failures of mobile offshore drilling platforms stationed within the Gulf of Mexico. A proposed failure mechanism is caused by out-of-plane loading. The current status of DEA holding capacity is based on empirical design charts and does not include the effects of out-of-plane loading. Experimental modeling using a 1:10 scale generic DEA was performed at the Haynes Coastal Engineering Laboratory at Texas A & M University to examine the effects of out-of-plane load conditions. Instrumentation and specialized devices were constructed to measure the anchor's trajectory through a representative sample of Gulf of Mexico clay with average un-drained shear strength of 0.764 kPa (16 psf). The sediment basin allowed for drag distances of 4.87 m (16 ft) and an embedment depth of 1.37 m (4.5 ft). The measurements included pitch and roll of the anchor and line tension measured at the shank pad-eye. The variables modeled were fluke angle settings of 22°, 36° and 50°. The initial towline angle was varied from a minimum of 5° to upwards of 20°. Surface out-of-plane angles of 45° and 90° and embedment loading of 15°, 30° and 45° were examined. Curves of the ultimate holding capacity with respect to the out-of-plane towline angle and ultimate embedment depth were developed as functions of out-of-plane loading angles. Analysis of the rate effect indicates that a 46 percent increase in towing velocity causes an average 3 percent increase of holding capacity. The 50° fluke angle embeds an average of 0.7 fluke lengths deeper and has a holding capacity of 0.73 units greater than the 36° setting. The surface out-of-plane tests have a 5.1 percent reduction in holding capacity as the out-of-plane load angle increases from 45° to 90°. For all one fluke length initial towing distance tests, the ultimate holding capacity increases and the ultimate embedment depth decreases as the out-of-plane towing angle increases from 15° to 45°. The three fluke length initial towing distance tests indicate a contrasting trend, in that as the out-of-plane tow angle increases, both the ultimate holding capacity and ultimate embedment depth decrease.

Mathematical modelling using advanced approach based on the neural networks has been applied to the control and the quality optimisation in the main processes of steelwork such as the ladle metallurgical treatment and continuous casting. Particular importance has been given to the improvement of breakout prediction system and the reduction in the rate of false alarm generated by the conventional breakout detection system. Prediction of the chemical composition and temperature of liquid steel in the ladle has been achieved by neural networks and linear model. This prediction can be considered as a soft sensor. Slab surface temperature stabilisation on the basis of the casting events has been controlled by a neural networks algorithm, that gives an improvement in the surface temperature fluctuation in comparison to the conventional control system which is based on the PID controller. Quality monitoring and classification is also achieved by a neural network which is related to the breakout detection system. This technique achieves a classification of different defects based on the different alarm signal given by the breakout prediction system. Fault detection and process monitoring is developed using neural networks modelling. All models are developed on basis of practical operating database obtained from the iron and steel industry.

This research demonstrates the usage of numerical acoustics to model sound and vibrational energy propagation in HVAC ducts and plenums. Noise and vibration in HVAC systems propagates along three primary paths that can be classified as airborne direct, airborne indirect and structure-borne. The airborne direct path was simulated using acoustic FEM with special boundary conditions to handle the diffuse acoustic field loading and the baffled termination. The insertion loss for a number of different plenum geometries was compared to published measurement results. Results were in good agreement both below and above the cutoff frequency. Additionally, the airborne indirect path, often termed breakout noise by the HVAC community, was assessed using Statistical Energy Analysis (SEA). This path was examined experimentally by placing a loudspeaker inside the air handler and measuring the sound power transmitted through the walls. SEA results compared favorably with the measured results in one-third octave bands even at low frequencies. Finally, the structure-borne path was considered by exciting the walls of the aforementioned air handler using an electromagnetic shaker. The panel vibration and the sound power radiated from the panels were measured. Results were compared with the SEA with good agreement provided that SEA loss factors were determined experimentally.