Yes / Empirical results of an electrically small printed monopole antenna is described with fractional bandwidth of 185% (115 MHz–2.90 GHz) for return-loss better than 10 dB, peak gain and radiation efficiency at 1.45 GHz of 2.35 dBi and 78.8%, respectively. The antenna geometry can be approximated to a back-to-back triangular shaped patch structure that is excited through a common feed-line with a meander-line T-shape divider. The truncated ground-plane includes a central stub located underneath the feed-line. The impedance bandwidth of the antenna is enhanced with the inclusion of meander-line slots in the patch and four double split-ring resonators on the underside of the radiating patches. The antenna radiates approximately omnidirectionally to provide coverage over a large part of VHF, whole of UHF, entire of L-band and some parts of S-band. The antenna has dimensions of 48.32×43.72×0.8 mm3, which is corresponding with the electrical size of 0.235λ_0×0.211λ_0×0.003λ_0, where λ_0 is free-space wavelength at 1.45 GHz. The proposed low-profile low-cost antenna is suitable for application in wideband wireless communications systems. / H2020-MSCA-ITN-2016 SECRET-722424 and UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1

The emergence of silicon-carbide (SiC) devices has been a 'game changer' in the field of power electronics. With desirable material properties such as low-loss characteristics, high blocking voltage, and high junction temperature operation, they are expected to drastically increase the power density of power electronics systems. Recent state-of-the-art designs show the power density over 17 ; however, certain factors limit the power density to increase beyond this limit. In this dissertation, three key factors are selected to increase the power density of SiC-based grid-connected three-phase converters. Throughout this dissertation, the techniques and strategies to increase the power density of SiC three-phase converters were investigated. Firstly, a magnetic integration method was introduced for the coupled inductors in the interleaved three-phase converters. Due to limited current-capacity compared to the silicon insulated-gate bipolar transistors (Si-IGBTs), discrete SiC devices or SiC modules, operate in parallel to handle a large current. When three-phase inverters are paralleled, interleaving can be used, and coupled inductors are employed to limit the circulating current. In Chapter 2, the conventional integration method was extended to integrate three coupled inductors into two; one for differential-mode circulating current and the other for common-mode circulating current. By comparing with prior research work, a 20% reduction in size and weight is demonstrated. From Chapter 3 to Chapter 5, a full-SiC uninterruptible power supply (UPS) was investigated. With the high switching frequency and fast switching dynamics of SiC devices, strategies on electromagnetic inference become more important, compared to Si-IGBT based inverters. Chapter 3 focuses on a common-mode equivalent circuit model for a topology and pulse width modulation (PWM) scheme selection, to set a noise mitigation strategy in the design phase. A three terminal common-mode electromagnetic interference (EMI) model is proposed, which predicts the impact of the dc-dc stage and a large battery-rack on the output CM noise. Based on the model, severe deterioration of noise by the dc-dc stage and battery-rack can be predicted. Special attention was paid on the selection of the dc-dc stage's topology and the PWM scheme to minimize the impact. With the mitigation strategy, a maximum 16 dB reduction on CM EMI can be achieved for a wide frequency range. In Chapter 4, an active PWM scheme for a full-SiC three-level back-to-back converter was proposed. The PWM scheme targets the size reduction of two key components: dc-link capacitors and a common-mode EMI filter. The increase in switching frequency calls for a large common-mode EMI filter, and dc-link capacitors in the three-level topology may take a considerable portion in the total volume. To reduce the common-mode noise emission, different combinations of the voltage vectors are investigated to generate center-aligned single pulse common-mode voltage. By such an alignment of common-mode voltage with different vector combinations, noise cancellation between the rectifier and the inverter can be maximally utilized, while the balancing of neutral point voltage can be achieved by the transition between the combinations. Also, to reduce the size of the dc-link capacitor for the three-level back-to-back converter, a compensation algorithm for neutral point voltage unbalance was developed for both differential-mode voltage and the common-mode voltage of the ac-ac stage. The experimental results show a 4 dB reduction on CM EMI, which leads to a 30% reduction on the required CM inductance value. When a 10% variation of neutral point voltage can be handled, the dc-link capacitance can be reduced by 56%. In Chapter 5, a 20 kW full-SiC UPS prototype was built to demonstrate a possible size-reduction with the proposed PWM scheme, as well as a selection of topologies and PWM schemes based on the model. The power density and efficiency are compared with the state-of-the-art Si-IGBT based UPSs. Chapter 6 seeks to improve power density by a change in a modulation method. Triangular conduction mode (TCM) operation of the three-level full-SiC inverter was investigated. The switching loss of SiC devices is reported to be concentrated on the turn-on instant. With zero-voltage turn-on of all switches, the switching frequency of a three-level three-phase SiC inverter can be drastically increased, compared to the hard-switching operation. This contributes to the size-reduction of the filter inductors and EMI filters. Based on the design to achieve a 99% peak efficiency, a comparison was made with a full-SiC three-level inverter, operating in continuous conduction mode (CCM), to verify the benefit of the soft switching scheme on the power density. A design procedure for an LCL filter of paralleled TCM inverters was developed. With 3.5 times high switching frequency, the total weight of the filter stage of the TCM inverter can be reduced by 15%, compared to that of the CCM inverter. Throughout this dissertation, techniques for size reduction of key components are introduced, including coupled inductors in parallel inverters, an EMI filter, dc-link capacitors, and the main boost inductor. From Chapter 2 to 5, the physical size or required value of these key components could be reduced by 20% to 56% by different schemes such as magnetic integration, EMI mitigation strategy through modeling, and an active PWM scheme. An optimization result for a full-SiC UPS showed a 40% decrease in the total volume, compared to the state-of-the-art Si-IGBT solution. Soft-switching modulation for SiC-based three-phase inverters can bring a significant increase in the switching frequency and has the potential to enhance power-density notably. A three-level three-phase full-SiC 40 kW PV inverter with TCM operation contributed to a 15% reduction on the filter weight. / Doctor of Philosophy / The power density of a power electronics system is regarded as an indicator of technological advances. The higher the power density of the power supply, the more power it can generate with the given volume and weight. The size requirement on power electronics has been driven towards tighter limits, as the dependency on electric energy increases with the electrification of transportation and the emergence of grid-connected renewable energy sources. However, the efficiency of a power electronics system is an essential factor and is regarded as a trade-off with the power density. The size of power electronics systems is largely impacted by its magnetic components for filtering, as well as its cooling system, such as a heatsink. Once the switching frequency of power semiconductors is increased to lower the burden on filtering, more loss is generated from filters and semiconductors, thus enlarging the size of the cooling system. Therefore, considering the efficiency has to be maintained at a reasonable value, the power density of Si-based converters appears to be saturated. With the emergence of wide-bandgap devices such as silicon carbide (SiC) or gallium nitride (GaN), the switching frequency of power devices can be significantly increased. This is a result of superior material properties, compared to Si-based power semiconductors. For grid-connected applications, SiC devices are adopted, due to the limitations of voltage ratings in GaN devices. Before commercial SiC devices were available, the power density of SiC- based three-phase inverters was expected to go over 20 𝑘𝑊 𝑑𝑚3 ⁄ . However, the state-of-the art designs shows the power density around 3 ~ 4 𝑘𝑊 𝑑𝑚3 ⁄ , and at most 17 𝑘𝑊 𝑑𝑚3 ⁄ . The SiC devices could increase the power density, but they have not reached the level expected. The adoption of SiC devices with faster switching was not a panacea for power density improvement. This dissertation starts with an analysis of the factors that prevent power density improvement of SiC-based, grid-connected, three-phase inverters. Three factors were identified: a limited increase in the switching frequency, large high-frequency noise generation to be filtered, and smaller but still significant magnetic components. Using a generic design procedure for three-phase inverters, each chapter seeks to frame a strategy and develop techniques to enhance the power density. For smaller magnetic components, a magnetic integration scheme is proposed for paralleled ac-dc converters. To reduce the size of the noise filter, an accurate modeling approach was taken to predict the noise phenomena during the design phase. Also, a modulation scheme to minimize the noise generation of the ac-ac stage is proposed. The validity of the proposed technique was verified by a full-SiC three-phase uninterruptible power supply with optimized hardware design. Lastly, the benefit of soft-switching modulation, which leads to a significant increase in switching frequency, was analyzed. The hardware optimization procedure was developed and compared to hard-switched three-phase inverters.

Yes / Purpose - The COVID-19 pandemic has caused significant disruptions to global supply chains (SCs), affecting the production, distribution, and transportation of goods and ser- vices. To mitigate these disruptions, it is essential to identify the barriers that have im- peded the seamless operation of SCs. This study identifies these barriers and assesses their impact on supply chain network (SCN). Design/methodology/approach - To determine the relative importance of different bar- riers and rank the affected industries, a hybrid approach was employed, combining the best-worst method (BWM) and the technique for order preference by similarity to an ideal solution (TOPSIS). To accommodate the inherent uncertainties associated with the pan- demic, a triangular fuzzy TOPSIS was used to represent the linguistic variable ratings provided by decision-makers. Findings - The study found that the airlines and hospitality industry was the most affected by the barriers, accounting for 46% of the total, followed by the healthcare industry (23%), the manufacturing industry (19%), and finally the consumer and retail industry (17%). Research limitation/implications - This study is limited to the four critical industries and nine identified barriers. Other industries and barriers may have different weights and rankings. Nevertheless, the findings offer valuable insights for decision-makers in SC management, aiding them in mitigating the impact of COVID-19 on their operations and enhancing their resilience against future disruptions. Originality/value - This study enhances our understanding of COVID-19’s impact on SCN and provides a framework for assessing disruptions using multi-criteria decision-making processes. The hybrid approach of BWM and TOPSIS in a fuzzy environment is unique and offers potential applicability in various evaluation contexts.

With the advances in the computing world, computational fluid dynamics (CFD) is becoming more and more critical tool in the field of fluid dynamics. In the past few decades, a huge number of CFD models have been developed with ever improved performance. In this research a robust CFD model, called Riemann2D, is extended to model flow over a mobile bed and applied to a full scale dam break problem. Riemann2D, an object oriented hyperbolic solver that solves shallow water equations with an unstructured triangular mesh and using high resolution shock capturing methods, provides a generic framework for the solution of hyperbolic problems. The object-oriented design of Riemann2D has the flexibility to apply the model to any type of hyperbolic problem with the addition of new information and inheriting the common components from the generic part of the model. In a part of this work, this feature of Riemann2D is exploited to enhance the model capabilities to compute flow over mobile beds. This is achieved by incorporating the two dimensional version of the one dimensional non-capacity model for erodible bed hydraulics by Cao et al. (2004). A few novel and simple algorithms are included, to track the wet/dry and dry/wet fronts over abruptly varying topography and stabilize the solution while using high resolution shock capturing methods. The negative depths computed from the surface gradient by the limiters are algebraically adjusted to ensure depth positivity. The friction term contribution in the source term, that creates unphysical values near the wet/dry fronts, are resolved by the introduction of a limiting value for the friction term. The model is validated using an extensive variety of tests both on fixed and mobile beds. The results are compared with the analytical, numerical and experimental results available in the literature. The model is also tested against the actual field data of 1957 Malpasset dam break. Finally, the model is applied to simulate dam break flow of Warsak Dam in Pakistan. Remotely sensed topographic data of Warsak dam is used to improve the accuracy of the solution. The study reveals from the thorough testing and application of the model that the simulated results are in close agreement with the available analytical, numerical and experimental results. The high resolution shock capturing methods give far better results than the traditional numerical schemes. It is also concluded that the object oriented CFD model is very easy to adapt and extend without changing the generic part of the model.

This multi-disciplinary study explores a field of enquiry at the boundaries of information science and development studies. It is concerned with the facilitation of knowledge processes - processes of knowledge exchange and co-creation - in the international development sector. Additionally, this study considers the importance of human relationships and social networks (and power), and studies these in knowledge intermediation projects. The main gaps that are addressed regard the understanding of intermediating knowledge process concerned with learners situated (partly) across cultural, language, and political boundaries in developing countries. Such projects/programmes/approaches, coined South-South knowledge exchanges by the World Bank, have only seen very limited amount of research; the foci of this research are human relationships and initiation acts, which add further novelty. By mirroring ideas of triangular and South-South collaboration the thesis explores knowledge intermediation projects and three roles played by actors participating in such projects: the intermediary and facilitator of knowledge processes (usually backed by a funding body), someone sharing knowledge (knowledge holders), and someone learning from others (knowledge seeker). This study not only shows how these roles apply to knowledge intermediation projects but also addresses their influence on relational elements at the interpersonal level. Two case studies are used to show how knowledge intermediation projects in the international development sector are shaped by their approach (demand initiated, facilitator/funder initiated), especially in terms of the relationships they foster. The sociology of knowledge approach to discourse analysis (SKAD) is used in the study of the case studies, which is supplemented by social network analysis. After linking the discovered relationship patterns to the initiation acts in the respective case studies a picture emerges that offers two broad insights. Firstly, facilitator/funder initiation of South-South knowledge intermediation projects appears to lead to many potential relationships, most of them irrelevant to an individual and, therefore, unestablished. Secondly, demand initiation of South-South knowledge intermediation projects appears to lead to very few, yet highly relevant, relationships.

Made available in DSpace on 2016-04-28T20:37:52Z (GMT). No. of bitstreams: 1 Claudia Dias Rosa.pdf: 1256770 bytes, checksum: 1ce30b3fd4fcaef04c1ea6b5cb6b0780 (MD5) Previous issue date: 2011-10-25 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Devoted to Winnicottian psychoanalysis, this study has the following objectives: a) to analyze the father s contribution to the personal maturational process in its various stages; b) to explain possible paternal failures and how they are connected with the etiology of emotional disorders; c) to illustrate these failures and their consequences from early stages to that of triangular relationships. At the beginning of life, although the baby is not mature enough to establish a relationship with the father as a father, the paternal presence is fundamental to help the mother to be good enough or to make this task difficult to the mother. In the stage of concern, the child may be helped or not by the father in regard to the capacity of tolerating the conflict between love and hate. Finally, in the stage of triangular relationships, once the healthy child is already mature enough to establish, as a full person, direct relationships with the father (as a full person too), paternal contributions or failures influence directly the solution of the child s conflicts in regard to handling his/her instinctual drive s of genital order in his/her interpersonal relationships. Paternal failures were evaluated from the theoretical perspective and examined based on some clinical cases presented by Winnicott, according to maturational criteria which he suggested for the understanding of the etiology of emotional disorders / Este estudo, dedicado à psicanálise winnicottiana, tem por objetivo: a) analisar a contribuição do pai para o processo de amadurecimento pessoal em seus diversos estágios, b) explicitar as possíveis falhas paternas e a maneira como elas se relacionam com a etiologia dos distúrbios emocionais, c) ilustrar essas falhas e suas consequências, desde os estágios iniciais até o estágio das relações triangulares. No início da vida, ainda que o bebê não tenha suficiente maturidade para estabelecer uma relação com o pai como pai, a presença paterna é fundamental para ajudar a mãe a ser suficientemente boa ou prejudicá‐la nessa tarefa. No estágio do concernimento, a criança pode ser ajudada ou não pelo pai na aquisição da capacidade para tolerar o conflito entre o amor e o ódio. Por fim, no estágio das relações triangulares uma vez que a criança sadia já adquiriu maturidade suficiente para estabelecer, como pessoa inteira, relações diretas com o pai (sendo este também uma pessoa inteira), as contribuições ou as falhas paternas influenciam diretamente a resolução dos conflitos da criança relativos à administração dos seus impulsos instintuais do tipo genital em suas relações interpessoais. As falhas paternas foram avaliadas do ponto de vista teórico e estudadas a partir de alguns casos clínicos apresentados por Winnicott, seguindo os critérios maturacionais por ele propostos para a compreensão da etiologia dos transtornos emocionais

[pt] Essa tese apresenta uma abordagem alternativa para orçamento de capital, denominada Métodos Modificados de Avaliação de Projetos de Investimentos em Ambiente Fuzzy, para avaliação de projetos em condições de incerteza. O desenvolvimento da abordagem proposta está dividido em duas fases: na primeira fase, é estabelecido um modelo determinístico generalizado que prevê explicitamente a utilização dos custos de oportunidade associados com os fluxos de caixa intermediários de um projeto de investimento empresarial. Os pressupostos implícitos dos métodos modificados da taxa interna de retorno e do valor presente líquido são incluídos nos métodos do índice de lucratividade e do tempo de retorno do investimento total. Os indicadores resultantes são o índice de lucratividade modificado e o tempo de retorno do investimento modificado. Essa abordagem unificada tem a propriedade de coincidir as decisões de aceitação / rejeição de projetos de investimentos de mesmos horizontes de vida e escalas com as do valor presente líquido modificado e, portanto, maximizam a riqueza do acionista. Na segunda fase, números fuzzy triangulares são utilizados para representar as incertezas das variáveis de um projeto de investimento: os fluxos de caixa, as taxas de financiamento e de reinvestimento e a taxa de desconto ajustada ao risco. Os indicadores fuzzy resultantes são o valor presente líquido modificado, a taxa interna de retorno modificada, o índice de lucratividade modificado e o tempo de retorno do investimento modificado. A aplicação de custos de oportunidades e de critérios difusos para a atribuição dos valores das variáveis permite obter resultados mais realistas e compatíveis com as condições de mercado. Devido à complexidade dos cálculos envolvidos, novas funções financeiras de uso amigável são desenvolvidas utilizando Visual Basic for Applications do MS-Excel: três, para avaliação de projetos em condições de certeza (MVPL, MIL e MTRI) e quatro para avaliação em condições de incerteza (MVPLfuzzy, MTIRfuzzy, MILfuzzy e MTRIfuzzy). A principal contribuição dessa tese é a elaboração de uma nova abordagem unificada para orçamento de capital em condições de incerteza que enfatiza os pontos fortes dos métodos modificados do valor presente líquido e da taxa interna de retorno, enquanto contorna os conflitos e as desvantagens individuais dos métodos convencionais. Os resultados mostram que os métodos propostos são mais vantajosos e mais simples de se utilizar que outros métodos de avaliação de investimentos em condições de incerteza. / [en] This thesis presents an alternative approach to capital budgeting, named Fuzzy Modified Methods of Capital Budgeting, for evaluating investment projects under uncertainties. The development of the proposed approach is divided into two phases: in the first stage, a general deterministic model that explicitly provides for the use of the opportunity costs associated with the interim cash flows of a project is established. The implicit assumptions of the modified internal rate of return and modified net present value methods are included in the index of profitability and in the total payback period. The resulting indicators are the modified index of profitability and the modified total payback period. This unified approach has the property to match the decisions of acceptance / rejection of investment projects with same horizons of life and same scales with the decisions of the modified net present value method and therefore maximize shareholder wealth. In the second phase, triangular fuzzy numbers are used to represent the uncertainties of the project variables: cash flows and reinvestment, financing and risk-adjusted discount rates. The resulting indicators are the fuzzy modified net present value, the fuzzy modified internal rate of return, the fuzzy modified index of profitability and the fuzzy modified total payback period. The application of opportunity costs and fuzzy criteria for determining the variables allows obtaining more realists and consistent results with the market conditions. Due to the complexity of the calculations involved, new MS-Excel financial functions are developed by using Visual Basic for Applications: three functions for evaluating projects under conditions of certainty (MVPL, MIL and MTRI) and four functions for evaluating projects under uncertainties (MVPLfuzzy, MTIRfuzzy, MILfuzzy and MTRIfuzzy). The main contribution of this thesis is to develop a unifying approach to capital budgeting under uncertainty that emphasizes the strengths of the methods of modified net present value and modified internal rate of return, while bypassing the individual conflicts and drawbacks of the conventional methods. Results show that the proposed methods are more advantageous and simpler to use than other methods of investment appraisal under uncertainties.

隨著全球化經濟時代的來臨，台灣不可避免的將處於一個大競爭之環境中，為提高競爭力並降低營運成本，於是中小企業，甚至大型企業紛紛精簡人事成本及大幅裁員，或僅保留行政中心部門，而將生產線完全外部化（外包或廠外委託加工）。在台灣，外包制度等廠外勞動絕不僅是扮演企業生產的輔助性角色，其對於台灣經濟成長具有絕對地貢獻。外包制度中的勞工雖提供本身僅有的勞動力供企業使用，但往往因被視為次級勞動力市場之勞工，無法立於初級勞動力市場之勞工地位而享有勞動法的保障，不論其勞動報酬或工作條件通常低於從事類似性質工作的初級勞動力市場之勞工（歧視待遇）。 外包與代工依照傳統民法與現存勞動法的見解，應該屬於承攬契約的一種，而言典型的雇傭契約。所以現存理論上，從事代工與外包之承攬人與發包人（定作人）間的關係僅為承攬之關係，並非雇用關係，自然也不得享有勞動法中勞工之特殊保障。但在台灣社會社世界趨勢，是否即可簡單地聲稱該承攬人並非該定作人之受雇人，所以不受勞動法之涵蓋，該發包人（定作人）可以完全免除對於承攬人之社會義務呢？顯然ILO並不同意如此看法，國際勞動總署（International Labour Office）在1997年第85會期便對此議題進行討論並做成關於承攬勞動之具體的提案公約（以下稱承攬勞動公約）與提案建議書。雖然各會員國質疑ILO之承攬勞動公約是否在獨立承攬人的與傳統受雇人間成立第三種種類的勞工？承攬勞工是否享有完全的受雇人保障？使用人事業單位與承攬勞工之關係如何？此提案公約是否過度地侵犯了傳統商業之領域而影響了契約自由與經營選擇權的自由？但就勞工保護之目的言，ILO之承攬勞動公約及建議書僅係披露日漸增加的類雇用關係之承攬，而建立起一套遊戲規則。 雖然承攬勞動公約及建議書迄今尚未正式通過，但藉由對於公約及建議書內容之分析探討，應可以瞭解未來勞動力市場之趨勢及ILO的期待，最後透過本國法律體系與司法實務的分析，提出公約適用上可能的問題並促進所謂「承攬勞工」之保障。 / The first discussion of the question of contract labour took place at the 85th Session (1997) of the International Labour Conference. The International Labour Office prepared and communicated to the governments of member States a report containing a proposed Convention and a proposed Recommendation concerning contract labour, based on the conclusions adopted by the Conference at its 85thSession.based on this proposal text, named "Contract Labour Convention" and "Contract Labour Recommendation", "contract labour" was defined as "work performed for a natural or legal person (referred to as a "user enterprise") by a person (referred to as a "contract worker") where the work is performed by the worker personally under actual conditions of dependency on or subordination to the user enterprise and these conditions are similar to those that characterize an employment relationship under national law and practice and where either: (1) the work is performed pursuant to a direct contractual arrangement between the worker and the user enterprise; or (2) the worker is provided for the user enterprise by a subcontractor or an intermediary", resembling a specific relationship between "contract of service" and "contract for service". But the amendments or comments from member government of ILO were very complicated and strict, main confusion as follow: will the proposal Convention result in a brand new type of workers or "third category" of workers out of independent contractor and traditional employee? Will so called "contract worker" entitle to be covered by labour law and enjoy full employee''s right? Will an ILO instrument that deals with matters outside the direct employment relationship be inconsistent with current commercial law and practice and the policy of reducing the regulatory burden on business or improving employment opportunities? Would Contract labour be an extremely broad and complicated issue? Although lots of member governments took a oppositive position, but for the purpose of worker protection, "Contract Labour Convention" set up a new equal playing rule, might be too advanced but would be helpful and just. Although "Contract Labour Convention" still didn''t be approved by ILC, but through analyzing and discussing the proposal Convention text, we would realize the trend of future labour market and the expectancy of ILO. After analyzing national law structure and judgments of court and finding the inconsistent with proposal Convention, we would work out the problems and improve the protection of so-called "contract worker".

Abstract This study focuses on the development of a plate-shell element using the vector form intrinsic finite element (VFIFE) method to analyze the structural behavior of thin shell structure subjected to various exerting forces. The shell element employed here is the flat three-node triangular shell element proposed by Bathe and Ho, which is obtained by superimposing CST (constant strain triangle) element with DKT (discrete Kirchhoff theory) triangular plate element. The nodal coordinates, displacements, rotations, and the motion equations of the structure are defined in a fixed global set of coordinates. The strains of the shell element, the element internal nodal forces and the element stiffness matrix are defined in terms of co-rotational coordinates, which are corresponding to the configuration of the shell element. Based on the co-rotational coordinate principle, the nodal displacement between two adjacent time steps can be separated into displacements induced from rigid body motion or deformation, and the incremental internal nodal forces can also be obtained. Finally, following the Newton's 2nd law, the equations of motion can be built to analyze the dynamic responses of thin shell structures. The theory derived in this study, were further verified to be able to simulate the behavior of thin shell structures subjected to both static and dynamic loadings. This new analytical model was proved to be an effective tool that can be an alternertive to traditional finite element procedure to solve for complicated engineering problems in thin shell structures.

Many physical problems lead to boundary value problems for partial differential equations, which can be solved with the finite element method. In order to construct adaptive solution algorithms or to measure the error one aims at reliable a posteriori error estimators. Many such estimators are known, as well as their theoretical foundation. Some boundary value problems yield so-called anisotropic solutions (e.g. with boundary layers). Then anisotropic finite element meshes can be advantageous. However, the common error estimators for isotropic meshes fail when applied to anisotropic meshes, or they were not investigated yet. For rectangular or cuboidal anisotropic meshes a modified error estimator had already been derived. In this paper error estimators for anisotropic tetrahedral or triangular meshes are considered. Such meshes offer a greater geometrical flexibility. For the Poisson equation we introduce a residual error estimator, an estimator based on a local problem, several Zienkiewicz-Zhu estimators, and an L_2 error estimator, respectively. A corresponding mathematical theory is given.For a singularly perturbed reaction-diffusion equation a residual error estimator is derived as well. The numerical examples demonstrate that reliable and efficient error estimation is possible on anisotropic meshes. The analysis basically relies on two important tools, namely anisotropic interpolation error estimates and the so-called bubble functions. Moreover, the correspondence of an anisotropic mesh with an anisotropic solution plays a vital role. AMS(MOS): 65N30, 65N15, 35B25