Finite difference time domain analysis of fractal antennas used in wireless communications

The advances in wireless technology and the ever-growing demand for multiband and smaller antennas in wireless communications has led to the field of mathematics known as fractal. The use of fractal geometry in antenna design has created a significant amount of interest within the wireless communications societies and most importantly, antenna design. This thesis investigates the performance and optimization of fractal antennas used in wireless communications. The principle analytical tool utilized in the study is the Finite Difference Time Domain technique (FDTD). This numerical method was applied to calculate the electromagnetic propagation characteristics of the Sierpinski gasket and Koch snowflake fractal antennas. Numerical results were computed for the two fractal antennas and compared to a conventional antenna. The input impedance, radiation pattern, the return loss and far field condition of these antennas are computed and analyzed. The Finite Difference Time Domain (FDTD) simulated results were collected and showed to be in good agreement

Mutualism in Architecture: An Architecture of the In-Between

Architecture is a system of complex relationships. Embodied within architecture are ideas concerning built and natural form and how these two types of form interact to produce what we define as architecture. Built form without natural form is building. Natural form without building is landscape. It is this in-between area where architecture lies. Mutualism is a process by which two seemingly opposite organisms interact in such a way as to benefit one another. It is through this approach that architecture can aspire to be more than a building. Mutualistic architecture, by its very nature, is a holistic system with the whole greater than the sum of its parts. Individual parts alone do not constitute architecture. Architecture emerges when the parts are assembled into a single organism. Examination of both the built form and the natural form must be analyzed and then synthesized to determine how they will interact in a mutualisc and harmonious way. Through the use of mutualism, architecture no longer is an either/or proposal but rather a more inclusive both/and. The series of relationships inherent in mutualistic architecture exist on the site, building and part scale. Architecture is an inclusive discipline that, if allowed, can result in interesting and unique solutions. Architecture is not built form devoid of its presence of nature. A mutualistic architecture is, by its very definition, an inclusive discipline that allows for diversity and integration. In a symbiotic architecture, the built environment and the non man-made world exist in harmony within an architectural design

A Woman’s Identity as Depicted in Angelou’s Poem “Woman Work”

This article analyzes Maya Angelou‟s poem “Woman Work”. This poem talks about identity which is described by Maya Angelou through her feelings and ideas. The objective of this research is to study Maya Angelou‟s search of identity which is depicted through the poem.This article uses an expressive approach because this approach is the most suitable for learning the poet‟s perspective on woman identity through her works. Library research is employed to support the analysis.The result of the analysis implies that the speaker‟s position is a woman who has a role in society as a mother, worker and slave. The speaker carries out all jobs in the house and outside. However, the speaker expresses a process of her journey to find her identity which is reflected in the poem. The speaker tries to prove that identity is an important part of her qualities that must be maintained.In this poem the speaker indicates that she becomes a woman who is more confident and proud. It is the result of her process of maturity that is expressed by her that makes her realizes the truth of her identity. The speaker reveals the process of her life that is faced by her to display that she is a strong woman

A Potential-Field-Based Multilevel Algorithm for Drawing Large Graphs

The aim of automatic graph drawing is to compute a well-readable layout of a given graph G=(V,E). One very popular class of algorithms for drawing general graphs are force-directed methods. These methods generate drawings of G in the plane so that each edge is represented by a straight line connecting its two adjacent nodes. The computation of the drawings is based on associating G with a physical model. Then, the algorithms iteratively try to find a placement of the nodes so that the total energy of the physical system is minimal. Several force-directed methods can visualize large graphs containing many thousands of vertices in reasonable time. However, only some of these methods guarantee a sub-quadratic running time in special cases or under certain assumptions, but not in general. The others are not sub-quadratic at all. We develop a new force-directed algorithm that is based on a combination of an efficient multilevel strategy and a method for approximating the repulsive forces in the system by rapidly evaluating potential fields. The worst-case running time of the new method is O(|V| log|V|+|E|) with linear memory requirements. In practice, the algorithm generates nice drawings of graphs containing up to 100000 nodes in less than five minutes. Furthermore, it clearly visualizes even the structures of those graphs that turned out to be challenging for other tested methods

NO SIMPLE TRADEOFFS: CENTAUREA PLANTS FROM AMERICA ARE BETTER COMPETITORS AND DEFENDERS THAN PLANTS FROM THE NATIVE RANGE

Two non-mutually exclusive hypotheses for invasive success have important evolutionary implications. The \u27natural enemies\u27 hypothesis posits that exotic invaders explode in abundance because they are not suppressed by specialist herbivore consumers in their invaded range. The \u27novel weapons\u27 hypothesis posits that exotic invaders explode in abundance because they possess biochemicals that are more effective against evolutionarily naïve plants, microbes, and generalist herbivores than against those species that have evolved tolerance in their communities of origin. I explored the potential for novel allelopathic or herbivore defense biochemicals as a potential alternative mechanism to tradeoff-driven evolution of increased competitive ability in invasive plants by comparing growth, reproduction, competitive effect and response, and defense capabilities of invasive North American populations of Centaurea maculosa to populations in Europe, where the species is native. I found that Centaurea from North America were larger, but produced fewer flowers than plants from European populations. North American Centaurea demonstrated much stronger competitive effects and responses than European Centaurea against North American grasses. Importantly, competitive superiority did not appear to come at a cost to herbivore defense. North American Centaurea genotypes were better defended against specialist and generalist consumers, and showed both a stronger inhibitory effect on the consumers (resistance) and a better ability to grow in response to attack by herbivores (tolerance). Better defense by North Americans corresponded with higher constitutive levels of biochemical defense compound precursors, tougher leaves, and more leaf trichomes than Europeans. North American F1 progeny of field collected lines retained the traits of larger size and greater leaf toughness suggesting that genetic differences, rather than maternal effects, caused the intercontinental differences. My results indicate that the evolution of increased competitive ability may not always be driven by simple physiological tradeoffs between the allocation of energy or resources to growth or to defense. Instead, I hypothesize that new plant neighbors and generalist herbivores encountered by Centaurea in its invaded range appear to exert strong directional selection on the weed\u27s competitive and defense traits

Feasibility study of Preventing Snow Accumulations on Roofs using Airflows

This thesis is intended to contribute to research in cold climate engineering. Further it intends to provide a principle solution for structural and avalanche safety due to snowfall on roofs. We have conducted a feasibility study of preventing snow from accumulating on roofs using airflows. This includes empirical, numerical and experimental methods. Snow loads on roofs makes great impact on structural safety and is the cause of annual injuries due to snow removal. Studies have shown that incidents related to snow clearing activities occurs more frequent in winter seasons with heavy snowfall (Bylund, Johansson & Albertsson, 2016, p. 107). At the same time, several climate projections predict that the annual rainfall will increase significantly, along with increased global temperature. However, for several places in cold climate regions, the rise in temperature will not be enough for the rain to stay liquified. The consequences of increased snowfall can be severe, especially for lightweight structures or structures built according to outdated standards. Regardless of the climate changes, risks for humans associated with snow loads on roofs is present. To assess the risks for human and assets a PHA is conducted and supported by risk matrices and bow-tie method. The experiments are based on empiricism and CFD simulations of airflows. To generate airflows, a compressor was used as source and pneumatic hoses from Festo was applied. The falling snow seemed to behave as intended - to a certain extent - by the influence of airflows. Due to challenges related to the experiments, we were not able to efficiently prevent snow from accumulating at the surface. However, from the results and discussion it emerges potentials for achieving the purpose. If the design chosen in this study is applicable and how it can be improved is concluded in the last chapter, followed by suggestions for further work

Real-time rendering and simulation of trees and snow

Tree models created by an industry used package are exported and the structure extracted in order to procedurally regenerate the geometric mesh, addressing the limitations of the application's standard output. The structure, once extracted, is used to fully generate a high quality skeleton for the tree, individually representing each section in every branch to give the greatest achievable level of freedom of deformation and animation. Around the generated skeleton, a new geometric mesh is wrapped using a single, continuous surface resulting in the removal of intersection based render artefacts. Surface smoothing and enhanced detail is added to the model dynamically using the GPU enhanced tessellation engine. A real-time snow accumulation system is developed to generate snow cover on a dynamic, animated scene. Occlusion techniques are used to project snow accumulating faces and map exposed areas to applied accumulation maps in the form of dynamic textures. Accumulation maps are xed to applied surfaces, allowing moving objects to maintain accumulated snow cover. Mesh generation is performed dynamically during the rendering pass using surface o�setting and tessellation to enhance required detail

Thinking and Learning through Creative Movement in the Classroom

In the past decade, the American school system has come under scrutiny. American children are scoring lower than children from other countries on standardized tests. What can be done to ensure that American students are able to compete in the technological world of today? Many educators believe that in order for children to fulfill their potential, they must be given more than information and knowledge. They must be taught how to think, how to use the knowledge they learn in school. Researchers such as Robert H. Ennis (1987, 1993) and Matthew Lipman (1995) believe thinking must be advanced in the schools. It must be practiced. Teachers must challenge their students and provide them with opportunities to make decisions, solve problems and be creative. Other researchers such as Harvard University\u27s Howard Gardner believe students will learn better if all of their intelligences are nurtured. This theory advances the belief that there is more to intelligence than an inborn general intelligence factor. The Multiple Intelligence (MI) theory believes that human cognitive competence is better described in terms of a set of abilities, talents, or mental skills, which we call \u27intelligences (Gardner, 1993 p. 15). The seven identified are the musical, bodily-kinesthetic, logical-mathematical, linguistic, spatial, interpersonal and intrapersonal. Gardner and his colleagues hold that students will benefit from instruction incorporating more than the verbal and logical intelligences. This thesis examines the aforementioned trends of teaching thinking skills and utilizing a multiple intelligence approach in the classroom. It then presents creative movement as a classroom activity which stimulates intelligences often overlooked in the classroom while also promoting critical and creative thinking skills in children. It has been shown in studies that movement can stimulate a child\u27s interest in school (Fowler, 1994). Creative movement stimulates decision making, problem solving and communication skills as well as the creative affinity needed to produce excellent thinkers. All of this research culminates in the development of a workshop for elementary school teachers. The workshop is designed to introduce teachers to creative movement so they have the knowledge and confidence to utilize creative movement as an educational tool within their own classrooms

Decentralized and adaptive sensor data routing

Wireless sensor network (WSN) has been attracting research efforts due to the rapidly increasing applications in military and civilian fields. An important issue in wireless sensor network is how to send information in an efficient and adaptive way. Information can be directly sent back to the base station or through a sequence of intermediate nodes. In the later case, it becomes the problem of routing. Current routing protocols can be categorized into two groups, namely table-drive (proactive) routing protocols and source-initiated on-demand (reactive) routing. For ad hoc wireless sensor network, routing protocols must deal with some unique constraints such as energy conservation, low bandwidth, high error rate and unpredictable topology, of which wired network might not possess. Thus, a routing protocol, which is energy efficient, self-adaptive and error tolerant is highly demanded. A new peer to peer (P2P) routing notion based on the theory of cellular automata has been put forward to solve this problem. We proposed two different models, namely Spin Glass (Physics) inspired model and Multi-fractal (Chemistry) inspired model. Our new routing models are distributed in computation and self-adaptive to topological disturbance. All these merits can not only save significant amount of communication and computation cost but also well adapt to the highly volatile environment of ad hoc WSN. With the cellular automata Cantor modeling tool, we implemented two dynamic link libraries (DLL) in C++ and the corresponding graphic display procedures in Tcl/tk. Results of each model’s routing ability are discussed and hopefully it will lead to new peer to peer algorithms, which can combine the advantages of current models