Low observable technology is used in order to prevent detection, or to delay detection. Radar cross section is an important parameter in aircraft survivability since it measures how detectable an object is with radar. To find the radar cross section Maxwell's equations are solved numerically in the time-domain using a finite difference scheme. This numerical method called Finite Difference Time Domain is very suitable for structures including complex materials. However, this numerical method needs to be verified for large scale simulations, due to numerical dispersion errors. Therefore it is desirable to verify the accuracy of the numerical simulations. In this project, the analytical solution to the multiple scattering by two spheres is implemented using the T-matrix formulation. The analytical solution to the scattering problem is first validated with the analytical Mie-series solution then compared to the Finite Difference Time Domain implementation. The results imply that the difference between the numerical and analytical solution is larger for higher frequencies and larger computational volumes. / Smygteknik används för att förhindra detektering, eller för att fördröja detektion av ett flygplan. Radarmålarea är en viktig parameter för skyddsprestanda hos flygplan eftersom den mäter hur detekterbar ett föremål är med radar. För att hitta radarmålarean löses Maxwells ekvationer numeriskt i tidsdomänen med hjälp av ett finit differensschema. Den numeriska metoden som kallas Finita differensmetoden i tidsdomän, är mycket lämplig för strukturer med komplexa material. Den numeriska metoden behöver valideras för storskaliga simuleringar eftersom det förekommer felaktigheter på grund av den numeriska dispersionen. Därför är det önskvärt att kontrollera riktigheten av de numeriska simuleringarna. I detta projekt, är den analytiska lösningen till multipelspridning av två sfärer implementerad med hjälp av T-matrismetoden. Den analytiska lösningen på spridningsproblemet valideras först mot den analytiska Mie-serielösningen och sedan jämförs den med resultatet av simuleringarna med Finita differensmetoden i tidsdomän. Resultaten antyder att skillnaden mellan den numeriska och analytiska lösningen är större för högre frekvenser och större beräkningsvolymer.

Master of Science / Department of Biology / A. Lorena Passarelli / Cydia pomonella granulovirus (CpGV) is a member of the Baculoviridae family of viruses. The CpGV open reading frame 46 (CpGV-ORF46) predicts a 545 amino acid protein that shares homology with matrix metalloproteases (MMPs), a family of zinc-dependent endopeptidases that degrade extracellular matrix proteins. In silico analyses revealed the presence of putative mmp genes in all species from the Betabaculovirus genus, while no mmps were identified in members of the Alphabaculovirus, Gammabaculovirus or Deltabaculovirus genera. Unlike most cellular MMPs, baculovirus MMPs do not have a propeptide domain, a domain involved in regulating MMP activation, or a hemopexin-like domain, which is necessary for substrate binding and specificity in many MMPs. However, Betabaculovirus MMPs do contain a predicted conserved zinc-binding motif (HEXGHXXGXXHS/T) within their catalytic domain. The function of CpGV-MMP and its effects on baculovirus replication in cultured cells and insect larvae were investigated. CpGV-MMP was expressed in and purified from Escherichia coli, and activity was measured using a generic MMP substrate in vitro. CpGV-MMP had in vitro activity and its activity was specifically inhibited by MMP inhibitors. To study the effects of CpGV-MMP on virus replication and dissemination, CpGV-MMP was expressed from Autographa californica nucleopolyhedrovirus (AcMNPV) under the control of a strong and constitutive promoter, the Drosophila heat shock 70 protein promoter. Expression of CpGV-MMP did not affect virus replication in cultured cells. The effects of expressing CpGV-MMP from AcMNPV during larval infection were evaluated in the presence or absence of the AcMNPV chitinase and cathepsin genes. Insect bioassays showed that the absence of cathepsin resulted in a significant delay in larval time of death; however, this delay was compensated by expression of CpGV-MMP. In addition, larval time of death was accelerated when cathepsin, chitinase, and CpGV-MMP were all expressed. Finally, we determined the effects of CpGV-MMP on larvae melanization and liquefaction. CpGV-MMP was able to promote larvae melanization in the absence of cathepsin. CpGV-MMP, in the absence of cathepsin, was not able to promote larvae liquefaction. When chitinase was engineered to be secreted from cells, CpGV-MMP rescued liquefaction in the absence of cathepsin. In conclusion, CpGV-MMP is a functional MMP which can enhance larvae mortality with the presence of cathepsin. In addition, CpGV-MMP can promote larvae melanization; however, it can only promote liquefaction when chitinase is engineered to be secreted from cells.

Call number: LD2668 .T4 1984 W53 / Master of Science

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / In this paper, we propose a dual-band switched beam system operating at 4.05 and 7.4 GHz. This system comprise of a dual frequency Butler matrix feeding a microstrip antenna array. Very good agreement is shown between measured and simulated data. The system can provide a tilted beam of ±13° and ±48° at the lowest frequency band and ±9° and ±27° at the higher frequency band.

In the field of aeronautics (Aircraft, helicopters, space launchers...), as in the field of the automobile, reducing the harmful effects of acoustics constitutes a major concern at the international level and justifies the call for further research. With these challenges in mind, the manufacturers have expressed the need for simple models immediately available as early as the stage of preliminary drafts. This Master's Thesis presents the study and the validation of three different approaches to meet this industrial need. The first approach is based on the propagation of waves in the structure; the second approach uses the technique of SEA by calculating the equivalent damping; and the last approach uses the modal technique.In the three approaches, the transfer matrix method has been used to study the succession of layers. Applying these approaches to some aircraft structures confirm their relevance in relation to more exact and costly methods, such as the finite elements method.

This thesis presents the research work regarding the solution of a localization problem in indoor WLANs by introducing a distributive time division multiplexed localization technique based on the convex semidefinite programming. Convex optimizations have proven to give promising results but have limitations of computational complexity for a larger problem size. In the case of localization problem the size is determined depending on the number of nodes to be localized. Thus a convex localization technique could not be applied to real time tracking of mobile nodes within the WLANs that are already providing computationally intensive real time multimedia services. Here we have developed a distributive technique to circumvent this problem such that we divide a larger network into computationally manageable smaller subnets. The division of a larger network is based on the mobility levels of the nodes. There are two types of nodes in a network; mobile, and stationery. We have placed the mobile nodes into separate subnets which are tagged as mobile whereas the stationary nodes are placed into subnets tagged as stationary. The purpose of this classification of networks into subnets is to achieve a priority-based localization with a higher priority given to mobile subnets. Then the classified subnets are localized by scheduling them in a time division multiplexed way. For this purpose a time-frame is defined consisting of finite number of fixed duration time-slots such that within the slot duration a subnet could be localized. The subnets are scheduled within the frames with a 1:n ratio pattern that is within n number of frames each mobile subnet is localized n times while each stationary subnet consisting of stationary nodes is localized once. By using this priority-based scheduling we have achieved a real time tracking of mobile node positions by using the computationally intensive convex optimization technique. In addition, we present that the resultant distributive technique can be applied to a network having diverse node density that is a network with its nodes varying from very few to large numbers can be localized by increasing frame duration. This results in a scalable technique. In addition to computational complexity, another problem that arises while formulating the distance based localization as a convex optimization problem is the high-rank solution. We have also developed the solution based on virtual nodes to circumvent this problem. Virtual nodes are not real nodes but these are nodes that are only added within the network to achieve low rank realization. Finally, we developed a distributive 3D real-time localization technique that exploited the mobile user behaviour within the multi-storey indoor environments. The estimates of heights by using this technique were found to be coarse. Therefore, it can only be used to identify floors in which a node is located.

Solar Wireless Networked Control Systems (SWNCS) are a style of distributed control systems where sensors, actuators, and controllers are interconnected via a wireless communication network. This system setup has the benefit of low cost, flexibility, low weight, no wiring and simplicity of system diagnoses and maintenance. However, it also unavoidably calls some wireless network time delays and packet dropout into the design procedure. Solar lighting system offers a clean environment, therefore able to continue for a long period. SWNCS also offers multi Service infrastructure solution for both developed and undeveloped countries. The system provides wireless controller lighting, wireless communications network (WI-FI/WIMAX), CCTV surveillance, and wireless sensor for weather measurement which are all powered by solar energy.

Thesis (MBA)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Over the last 20-30 years, the adoption of matrix management has become ever increasingly popular especially in organizations developing new products and product lines. As with any new organizational design or structure, problems are experienced. These problems must be managed constructively in order for the organization to realize the design/structure's full potential. When managing problems associated with the matrix design, simple solutions can be sought: • Know what the matrix can do, as well as know its limitations. • Communicate this to all levels of staff in the organization. • Ensure that conflict that arises from a dual command system is dealt with quickly. On the other hand, capitalize on the matrix structure's advantages such as retain more information, multi-skill staff and realize economies of scale. The above are "old" management principles, however very sound. The matrix in itself will not determine the success or the failings of the organization. The responsibility lies with the management team and the maturity level of the organization. / AFRIKAANSE OPSOMMING: Die implementering van matriks bestuur, het gedurende die afgelope 2-3 dekades toenemend gewild geraak, veral in ondernemings wat nuwe produkte- of produklyne ontwikkel. Dit is inherent aan nuwe organisatoriese ontwerp of struktuurwysiging dat probleme ondervind word. Hierdie probleme moet konstruktiefbestuur word, sodat die organisasie die volle potensiaal van die nuwe of veranderde ontwerp of struktuur kan benut. Wanneer probleeme aangaande die matriks ontwerp bestuur word, kan eenvoudige oplossings oorweeg word: • Bekom 'n grondige kennis van die vermoëns van die matriks, sowel as die beperkings daarvan. • Verseker dat alle vlakke van personeel in die organisasie ten volle ingelig is. • Pas konflik bestuur tydig toe indien probleme ontstaan ingeval van 'n tweeledige rapportering/opdragstelsel. Kapitaliseer egter op die voordele van matriks bestuur: • Versamel en bestuur verbeterde inligting en inligtingstelsels. • Opleiding van personeel vir meerdoelige take. • Meer ekonomiese aanwending van beskikbare bronne. Bogenoemde is "ou", maar tog bewese en gesonde bestuurspraktyke. Die matriks self, kan nie die sukses of mislukking van 'n organisasie bepaal nie. Hierdie verantwoordlikheid is die taak van die bestuurspan en die vermoënsvlak van die organisasie.

Thesis (MBA)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Organisations are struggling to cope with the pace of change and the pressure is on for them either to adapt or die. Consequently, project management has become the sought after management process to deal with this unprecedented rate of change and for survival. Why is project management so attractive recently? Is it because of its emphasis on teamwork and multidisciplinary approach? Of course yes. Its holistic approach makes it very useful in unfamiliar and risky projects in which information is either scanty or overwhelming. As the business environment continues to become more chaotic, project management will continue to be the management tool of the 21st Century. The use of matrix organisation has been spreading in the last ten years in response to a number of new needs. It has usually been a compromise between contradictory requirements and particularly between pressures for a responsive and self-contained project or product organisation and the greater efficiency, expertise and the economies of scale of a functional or departmental structure. It has been seen as a way of dealing with greater environmental complexity and as a more democratic alternative to traditional hierarchical structures. This study project focuses on matrix management as a structuring tool for organisations in this century. The literature study is conducted within the field of project management although matrix management can fall in other fields of organisational development or strategic management. A guide to successful matrix management in organisations with specific reference to project management is examined by addressing questions like, why matrix management is important for project management? What are the obstacles in organisations to the application of matrix management? What are the rules and guidelines to make matrix management successful in organisations? These and other questions on this subject are answered. / AFRIKAANSE OPSOMMING: Organisasies sukkel om tred te hou met die vinnige tempo van verandering. Daar is voortdurend meer druk op organisasies om aan te pas ten einde te oorleef. Om hierdie ongekende druk op verandering en oorlewing te verwerk, het projekbestuur 'n gesogte bestuursproses geword. Is dit omdat projekbestuur klem lê op spanwerk en multi-dissiplinêre benadering? Die antwoord is vanselfsprekend ja. Die holistiese benadering van projekbestuur maak dit toepaslik in ongewone en riskante projekte waar informasie kan wissel tussen uiters skaars of oorweldigend baie. Soos wat die sake-omgewing meer chaoties word, behoort projekbestuur sy status as die bestuurstegniek van die 21 ste eeu voort te sit. Die aanwending van die matriksorganisasie het in die laaste tien jaar, in antwoord of verskeie nuwe behoeftes, uitgebrei. Die organisasie-tipe is normaalweg 'n kompromis tussen teenstrydige vereistes, en in besonder tussen die druk vir 'n lewenskragtige en selfonderhoudende projek- of produkorganisasie, en die groter doeltreffendheid, kundigheid, en ekonomieë van skaal van 'n funksionele of departementele struktuur. Die word gesien as 'n manier om met meer komplekse omgewings oor die weg te kom, en ook as 'n meer demokratiese alternatief tot die klassieke hierargiese struktuur. Hierdie studie-projek fokus op matrikbestuur as 'n tegniek van die organisasie-ontwerp vir hierdie nuwe eeu. Die literatuurstudie word beperk tot die veld van projekbestuur, alhoewel daar ook in ander studievelde van organisasie-ontwikkeling of strategiese bestuur aandag aan matrikbestuur gegee word. 'n Riglyn vir suksesvolle matriksbestuur in organisasies, met spesifieke verwysing na projekbestuur, word ondersoek deur seker pertinente vrae te vra. Waarom is matriksbestuur belangrik vir projekbestuur? Watter struikelblokke is daar in organisasies met betrekking tot die toepassing van matriksbestuur? Wat is die reëls en riglyne vir die suksessvolle aanwending van matriksbestuur in organisasies? Antwoorde op hierdie, en ander soortgelyke vrae rondom die onderwerp, word met hierdie studie verskaf.

The research is framed on the premise that designing buildings that can adapt by accommodating change easier and more cost-effectively provides an effective means to a desired end a more sustainable built environment. In this context, adaptability can be viewed as a means to decrease the amount of new construction (reduce), (re)activate underused or vacant building stock (reuse) and enhance disassembly/ deconstruction of components (reuse, recycle) - prolonging the useful life of buildings (reduce, reuse, recycle). The aim of the research is to gain a holistic overview of the concept of adaptability in the construction industry and provide an improved framework to design for, deploy and implement adaptability. An over-arching research question was posited to guide the inquiry: how can architects understand, communicate, design for and test the concept of adaptability in the context of the design process? The research followed Dubois and Gadde s (2002) systematic combining as an over-arching approach that continuously moves between the empirical world and theoretical models allowing the co-evolution of data collection and theory from the beginning as part of a non-linear process with the objective of matching theory with reality. An initial framework was abducted from a preliminary collection of data from which a set of mixed research methods was deployed to explore adaptability (interviews, building case studies, dependency structural matrices, practitioner surveys and workshop). Emergent from the data is an expanded and revised theory on designing for adaptability consisting of concepts, models and propositions. The models illustrate many of the casual links between the physical design structure of the building (e.g. plan depth, storey height) and the soft contingencies of a messy design/construction/occupation process (e.g. procurement route, funding methods, stakeholder mindsets). In an effort to enhance building adaptability, the abducted propositions suggest a shift in the way the industry values buildings and conducts aspects of the design process and how designer s approach designing for adaptability.