<p>Composite structures can lower the weight of an airliner significantly. The increased production cost, however, requires the application of cost-effective design strategies. Hence, a comparative value is required which is used for the evaluation of a design solution in terms of cost and weight. The direct operating cost (DOC) can be used as this comparative value; it captures all costs that arise when the aircraft is flown. In this work, a cost/weight optimization framework for composite structures is proposed. It takes into account manufacturing cost, non-destructive testing cost and the lifetime fuel consumption based on the weight of the aircraft, thus using a simplified version of the DOC as the objective function.</p><p>First, the different phases in the design of an aircraft are explained. It is then focused on the advantages and drawbacks of composite structures, the design constraints and allowables, and non-destructive inspection. Further, the topics of multiobjective optimization and the combined optimization of cost and weight are addressed. Manufacturing cost can be estimated by means of different techniques; here, feature-based cost estimations and parametric cost estimations proved to be most suitable for the proposed framework. Finally, a short summary of the appended papers is given.</p><p>The first paper contains a parametric study in which a skin/stringer panel is optimized for a series of cost/weight ratios (weight penalties) and material configurations. The weight penalty, defined as the specific lifetime fuel burn, is dependent on the fuel consumption of the aircraft, the fuel price and the viewpoint of the optimizer. It is concluded that the ideal choice of the design solution is neither low-cost nor low-weight but rather a combination thereof.</p><p>The second paper proposes the inclusion of non-destructive testing cost in the design process of the component, and the adjustment of the design strength of each laminate according to the inspection parameters. Hence, the scan pitch of the ultrasonic testing is regarded as a variable, representing an index for the (guaranteed) laminate quality. It is shown that the direct operating cost can be lowered when the quality level of the laminate is assigned and adjusted in an early design stage.</p>

In recent years, bridge foundations have been in the spotlight throughout the nation. Bridges built over running water are susceptible to erosion or scour around their foundations. The reduction in load capacity to piers and abutments pose a safety risk to highway motorists. It has become necessary for engineers to examine and monitor these "scour critical" bridges. The difficulty arises with subsurface foundations of which very little is known about their construction. Hence, the methods applied to analyzing "Unknown Foundations" have become a necessary topic of research. This thesis explores a method to determine foundation lengths. Similar to Sonic Echo / Impulse Response, this procedure measures reflected shock waves sent through concrete pilings. The technique is non-destructive in nature and is performed near the surface of the foundation. The test is performed on the side of the exposed piling. Current methods are limited by the fact that the tops of most pilings are inaccessible due to pilecaps or beams. Often times, pilings are embedded in stiff soils, which have a dampening effect on the stress waves. This thesis employs a method of analysis that will overcome such limitations and provide engineers with another tool to determine subsurface foundation lengths.

The objective of this thesis is to design and implement a rapid, reconfigurable and portable reader for wirelessly interrogating inductively coupled passive sensors. While the current method of impedance analyzer is sensitive and an accurate, the instruments used are bulky and slow, substantially hampering in-field testing and interrogation of sensors. Current methods cannot provide a quantifiable measure on minimum necessary read-speeds and instrument accuracy desirable for rapid sensing applications. This work summarizes the design and hardware implementation of two reader methods that address the aforementioned requirements. Both reader methods are based on a reflectometer approach: Swept-frequency Reflectometer Reader and Switched-frequency Interrogation Technique (SWIFT). The first method is a much faster alternative to in-lab and in-field testing for structural health monitoring, and is intended as an immediate replacement for the impedance analyzer method. Switched-frequency Interrogation is specifically designed to satisfy the need for rapid and accurate reading, potentially for in-motion sensing applications. This method provides a way of empirically relating minimum necessary read-time required for desired read-ranges. It also facilitates quantification of uncertainty in measurements, which is very critical in determining instrument accuracy in-field. The system design and implementation of both methods are described in detail and experimental results are presented to benchmark the performance of the readers. Issues of instrument reliability and practical limitations are also discussed, with potential solutions. Both methods are intended as universal techniques for wirelessly interrogating coupled passive sensors, not limited to their current form of implementation. / text

Vadovaujantis prof. B. Bitino (2004) mintimis, galima labai aiškiai atskirti moksleivių destruktyvaus elgesio vadybinį (valdymo) lygmenį ir jo praktinio realizavimo (pedagoginį) lygmenį. Visgi vadybinis - administracinis lygmuo negali būti atskirtas nuo tiesioginio pedagoginio proceso jau vien todėl, kad vadybinės priemonės turi remtis konkrečiais auklėjimo uždaviniais, įvertinant tiek teorines šio proceso prielaidas, tiek ir konkrečių taikytinų priemonių efektyvumą. Kitaip tariant, mokinių destruktyvaus elgesio vadyba turi remtis konkrečiais edukologijos, psichologijos ir kitų mokslo sričių, tiriančių asmenybę ir jos raidą, pasiekimais. Tik tuomet ji bus rezultatyvi ir efektyvi. Kita vertus, labai svarbu, kad taikomi vadybiniai modeliai būtų tinkami keliamiems pedagoginiams uždaviniams. Atliktas tyrimas parodė, kad ir mokiniai, ir mokytojai mato nemažai galimybių gerinti auklėjamąjį darbą.. Tačiau mokytojai įvairias vadybines priemones dažniausiai vertina kaip daug efektyvesnes nei mano mokiniai. Ir mokiniai, ir mokytojai vieningai akcentuoja didesnio dėmesio svarbą mokinių tarpusavio santykiams. Tyrimas parodė, kad 6-8 klasių mokiniai nėra pakankamai įsisąmoninę netinkamo (destruktyvaus) elgesio žalą pačiam mokiniui, mokymosi rezultatams ir tarpusavio santykiams su bendraamžiais ir mokytojais. Destruktyvi mokinio elgsena neretai priklauso nuo jo nesugebėjimo realizuoti savąjį „Aš“ pozityviais būdais. Tam turi įtakos ir mokytojo bei kitų specialistų dalykinė kompetencija... [toliau žr. visą tekstą] / According to the prof. B. Bitinas it is possible clearly distinguish between the managerial level of schoolchildren destructive behaviour and it’s practical realization (pedagogical) level. However managerial–administrative level can not be separated from direct pedagogical process because the managerial instruments shall go entirely with the concrete educational tasks, assessing the theoretical preconditions for this process and effectiveness of possible to apply concrete tools. In other words, the management of schoolchildren destructive behaviour has appeal to the concrete achievements of science analysing personality and it’s evolution as educology, psychology and etc. Only then it could be effective and useful. But also it is very important that applied managerial models would be appropriate for raised pedagogical tasks. The accomplished research showed that schoolchildren of 6-8 class do not realize clearly the harm of bad (destructive) behaviour for themselves, learning results and relations between contemporaries and teachers. The appearance of schoolchild destructive behaviour usually depends on incapacity to realize his ego in positive ways. The teacher’s and other specialist’s competence, communication with schoolchildren skills also have influence. Both teachers and schoolchildren often assess similarly the appearance of schoolchildren destructive behaviour, it reasons and effective education methods. But also there are some essential differences. Knowing of... [to full text]

X-Ray Diffraction Contrast Tomography (DCT) is a recently developed, non-destructive synchrotron imaging technique which characterizes microstructure and grain orientation in polycrystalline materials in three dimensions (3D). By combining it with propagation based phase contrast tomography (PCT) it is for the first lime possible to observe in situ the 3D propagation behavior of short fatigue cracks (SFCs) within a set of fully characterized grains (orientation and shape). The combined approach, termed 3D X-ray Tomography of short cracks and Microstructure (3DXTSM), has been developed on the metastable beta titanium alloy "Beta21S". A large part of this work deals with the development of the 3DXTSM methodology. In the combined dataset, each point on the 3D fracture surface can be associated with a multidimensional data structure containing variables describing the grain orientation, the local fracture surface normal and the propagation history. The method uses a surface mesh composed of triangles that describes the crack (in other words: the fracture surface) in the last propagation state measured. Grain orientations, crack fronts, local growth rates and grain boundaries can be visualized by assigning colors to this mesh. The data structure can be interrogated in a number of different ways. Tools for extracting pole figures and pole density distribution functions have been implemented. An algorithm was developed that is capable of measuring the 3D local growth rate of a crack containing branches. The accuracy of the grain boundaries as reconstructed with OCT was evaluated and the elastic constants of Beta21S were determined.

Une mesure adaptative vise à optimiser l'acquisition d'information sur un système à l'aide d'une boucle de rétroaction sur l'appareil de mesure. Dans notre dispositif d'électrodynamique en cavité, nous avons réalisé une mesure adaptative sur un système quantique, le champ micro-onde piégé dans une cavité supraconductrice de très grande finesse. Des atomes de Rydberg circulaires, interagissant dispersivement avec le champ, réalisent une série de mesures dites "faibles", aboutissant à la mesure quantique non destructive du nombre de photons dans le mode. La prise en compte des résultats des mesures successives, de l'action en retour sur le système, et de l'ensemble des imperfections expérimentales, permet à un ordinateur de contrôle d'effectuer une estimation en temps réel de l'état du champ. La phase de l'interféromètre de Ramsey qui définit la mesure réalisée sur les atomes est alors optimisée afin d'extraire un maximum d'information des détections ultérieures. Nous montrons que préparation d'états de Fock est nettement accélérée avec la méthode adaptative, par rapport à un protocole passif utilisant une alternance prédéfinie des phases de mesure. Cette réduction du temps de mesure est d'un grand intérêt en présence de décohérence, et pourrait par exemple être exploitée dans des protocoles de rétroaction quantique existants, où la rapidité de l'estimation d'état est cruciale.

For successful identification of structural defects in plates and pipes, it is essential to understand structural wave propagation characteristics such as dispersion relations. Analytical approaches to identify the dispersion relations of homogeneous, simple plates and circular pipes have been investigated by many researchers. However, for plates or pipes with irregular cross-sectional configurations or multi-layered composite structures, it is almost impossible to obtain the analytical dispersion relations and associated mode shapes. In addition, full numerical modeling approaches such as finite element (FE) methods are not economically feasible for high (e.g., ultrasonic) frequency analyses where an extremely large number of discretized meshes are required, resulting in significantly expensive computation. In order to address these limitations, Hybrid Analytical/Finite Element Methods (HAFEMs) are developed to model composite plates and pipes in a computationally-efficient manner. When a pipe system is used to transport a fluid, the dispersion curves obtained from a “hollow” pipe model can mislead non-destructive evaluation (NDE) results of the pipe system. In this study, the HAFEM procedure with solid elements is extended by developing fluid elements and solid-fluid boundary conditions, resulting in the dispersion curves of fluid-filled pipes. In addition, a HAFEM-based acoustic transfer function approach is suggested to consider a long pipe system assembled with multiple pipe sections with different cross-sections. For the validation of the proposed methods, experimental and full FE modeling results are compared to the results obtained from the HAFEM models. In order to detect structural defect locations in shell structures from defect-induced, subtle wave reflection signals and eliminate direct-excitation-induced and boundary-reflected, relatively-strong wave signals, a time-frequency MUSIC algorithm is applied to ultrasonic wave data measured by using an array of piezoelectric transducers. A normalized, structurally-damped, cylindrical 2-D steering vector is proposed to increase the spatial resolution of time-frequency MUSIC power results. A cross-shaped array is selected over a circular or linear array to further improve the spatial resolution and to avoid the mirrored virtual image effects of a linear array. Here, it is experimentally demonstrated that the proposed time-frequency MUSIC beamforming procedure can be used to identify structural defect locations on an aluminum plate by distinguishing the defect-induced waves from both the excitation-generated and boundary-reflected waves.

This thesis reports on the application of ground penetrating radar (GPR) as a non-destructive technique for the monitoring of ring separation in brick masonry arch bridges. In addition, research is reported on the assessment of the clay capping layer often used in construction as a waterproof backing to arches. The thrust of the research is numerical modelling, verified by large laboratory experiments. Due to the heterogeneity of these structures, the resultant signals from the interaction between the GPR system and the bridge are often complex and hence, hard to interpret. This highlighted the need to create a GPR numerical model that would allow the study of the attributes of reflected signals from various targets within the structure of the bridge. The GPR numerical analysis was undertaken using the finite-difference time-domain (FDTD) method. Since micro regions in the bridge structure need to be modelled, the introduction of subgrids of supporting finer spatial resolution into the standard FDTD method was considered essential in order to economise on the required computational resources. In the main part of this thesis, it is demonstrated how realistic numerical modelling of GPR using the FDTD method could greatly benefit from the implementation of subgrids into the conventional FDTD mesh. This is particularly important when (a) parts of the computational domain need to be modelled in detail (i.e., ring separation between the mortar layers and the brick units, which is the case studied in this thesis); and also (b) when there are features or regions in the overall computational mesh with values of high relative permittivity supporting propagation of waves at very short wavelengths. A scheme is presented that simplifies the process of implementing these subgrids into the traditional FDTD method. This scheme is based on the combination of the standard FDTD method and the unconditionally stable alternating-direction implicit (ADI) FDTD technique. Given that ADI-FDTD is unconditionally stable, its time-step can be set to any value that facilitates the accurate calculation of the electromagnetic fields. By doing so, the two grids can efficiently communicate information across their boundary without requiring to use a time-interpolation scheme. The performance of ADI-FDTD subgrids when implemented into the traditional FDTD method is discussed herein. The developed algorithm can handle cases where the subgrid crosses dielectrically inhomogeneous and/or conductive media. In addition, results from the comparison between the proposed scheme and a commonly employed purely FDTD subgridding technique are presented. After determination of the optimum ADI-FDTD scheme, numerical experiments were conducted and calibrated using GPR laboratory experiments. Good correlations were obtained between the numerical experiments and the actual GPR experiments. It was shown both numerically and experimentally that significant mortar loss between the masonry arch rings can be detected. Dry hairline delaminations between the mortar and the brick masonry are difficult to detect using standard GPR procedures. However, hairline faults containing water produce distinct and detectable GPR responses. In addition, the clay layer was successfully identified and its thickness calculated to a satisfactory accuracy.

Local government has to face new challenges and demands as they approach the 21st century, especially in view of the fact that the South African system of local government has been significantly altered since the first democratic local government elections which were held in November 1995 and July 1996. The integrated development plan (IDP) of a municipality reflects on the municipal council's vision for the long-term development of the municipality with special emphasis on the municipality's most critical development for service delivery purposes. The integrated development plan consists of separate plans developed for new initiatives to fit into the overall strategic planning framework as distinct from the normal operating and capital business plans for each of a Council's existing functions. The plans do not necessarily relate to completely new functions but may relate to changing the way a function operates, enhancing service levels of existing functions or even cutting back services provided by an existing function. Some IDP initiatives may stand apart as individual projects and some may have wide-spread impact across existing functional areas. Emanating from the above is a resultant conflict between administration management of a municipality and the rest of the workforce of the municipality. As a result of the lack of knowledge regarding conflict in a local authority within the framework of an integrated development plan for labour and the need for it to be managed correctly, it was decided to embark on this study and contribute to the existing knowledge on this subject. / Thesis (M.Com. (Industrial Sociology))--North-West University, Potchefstroom Campus, 2007.

South African organizations experienced more conflict in the past ten years because of all the changes in the management of labour relations. Employees at lower, middle and upper management levels within organizations are not well informed about the different types of conflict, the functionality and dysfunctionality of conflict, how conflict takes place within the different job-levels and how to manage and resolve it. Dysfunctional conflict can be destructive and it can affect the productivity of the organization. Because of the lack of knowledge regarding conflict within the steel organization and the necessity for it to be handled correctly, it was decided to seize the opportunity to contribute to the existing knowledge of conflict. Objectives of the study The major objectives of this study are as follows: To determine how literature conceptualizes conflict dynamics by examining theory, industrial sociology, organizational behaviour and general management. To determine the following aspects by means of an empirical study: - What the main reasons are for conflict within the steel organization. - How the handling of conflict differs among the middle and lower job levels within the organization. Research study and methodology The research study is divided into a theoretical and an empirical framework. Chapters 2, 3 and 4 outline the theoretical basis. Various aspects of conflict and handling or managing it are discussed in detail. The study employs the conflict theories of Ralph Dahrendorf and Karl Marx as points of departure, as found in chapter 2, in an attempt to provide a framework for the problem statement and to attempt the attainment of the set of objectives. This chapter discusses conflict and analyzes it as a social interaction characterized by force, strife and animosity. It also offers and analysis of Dahrendorf s and Marx's theories to determine their suitability to the study. Chapter 3 discusses conflict within a business context with reference to functional and dysfunctional conflict. different approaches to conflict. types of conflict, different reactions to conflict as well as its different stages. Chapter 4 addresses the course, handling and management of conflict by analyzing the conflict process while it keeps the theories of Marx and Dahrendorf in mind. Chapter 5 analyzes and describes the data and results found by means of empirical research according to specific statistical methods. The empirical study was conducted among the employees of a steel company. A standardised questionnaire and personal interviews were used. Major findings Chapter 6 consists of analysed information about the assembled data. The major findings of the study support the set of research objectives and prove all of them. Major findings include the following: Cooperation, discipline and communication are problem areas within the steel organization. A large number of employees show dissatisfaction about the nature and extent of their work. Some of the employees misuse their authority and this is a major cause of conflict. A total of 95% of the population show that they would like further training in the dynamics of conflict management. Half of the population show that they are unaware of any policies and procedures of conflict management in the steel company. Conclusion In conclusion as found in chapter 6 the study makes a number of recommendations centring on the training of employees to handle conflict and policy-making about conflict-handling and management. / Thesis (M.A. (Industrial Sociology))--North-West University, Potchefstroom Campus, 2006.