Introduction to frames

This survey gives an introduction to redundant signal representations called frames. These representations have recently emerged as yet another powerful tool in the signal processing toolbox and have become popular through use in numerous applications. Our aim is to familiarize a general audience with the area, while at the same time giving a snapshot of the current state-of-the-art

Discrete Wavelet Transforms

The discrete wavelet transform (DWT) algorithms have a firm position in processing of signals in several areas of research and industry. As DWT provides both octave-scale frequency and spatial timing of the analyzed signal, it is constantly used to solve and treat more and more advanced problems. The present book: Discrete Wavelet Transforms: Algorithms and Applications reviews the recent progress in discrete wavelet transform algorithms and applications. The book covers a wide range of methods (e.g. lifting, shift invariance, multi-scale analysis) for constructing DWTs. The book chapters are organized into four major parts. Part I describes the progress in hardware implementations of the DWT algorithms. Applications include multitone modulation for ADSL and equalization techniques, a scalable architecture for FPGA-implementation, lifting based algorithm for VLSI implementation, comparison between DWT and FFT based OFDM and modified SPIHT codec. Part II addresses image processing algorithms such as multiresolution approach for edge detection, low bit rate image compression, low complexity implementation of CQF wavelets and compression of multi-component images. Part III focuses watermaking DWT algorithms. Finally, Part IV describes shift invariant DWTs, DC lossless property, DWT based analysis and estimation of colored noise and an application of the wavelet Galerkin method. The chapters of the present book consist of both tutorial and highly advanced material. Therefore, the book is intended to be a reference text for graduate students and researchers to obtain state-of-the-art knowledge on specific applications

Convergence of packet communications over the evolved mobile networks; signal processing and protocol performance

In this thesis, the convergence of packet communications over the evolved mobile networks is studied. The Long Term Evolution (LTE) process is dominating the Third Generation Partnership Project (3GPP) in order to bring technologies to the markets in the spirit of continuous innovation. The global markets of mobile information services are growing towards the Mobile Information Society. The thesis begins with the principles and theories of the multiple-access transmission schemes, transmitter receiver techniques and signal processing algorithms. Next, packet communications and Internet protocols are referred from the IETF standards with the characteristics of mobile communications in the focus. The mobile network architecture and protocols bind together the evolved packet system of Internet communications to the radio access network technologies. Specifics of the traffic models are shortly visited for their statistical meaning in the radio performance analysis. Radio resource management algorithms and protocols, also procedures, are covered addressing their relevance for the system performance. Throughout these Chapters, the commonalities and differentiators of the WCDMA, WCDMA/HSPA and LTE are covered. The main outcome of the thesis is the performance analysis of the LTE technology beginning from the early discoveries to the analysis of various system features and finally converging to an extensive system analysis campaign. The system performance is analysed with the characteristics of voice over the Internet and best effort traffic of the Internet. These traffic classes represent the majority of the mobile traffic in the converged packet networks, and yet they are simple enough for a fair and generic analysis of technologies. The thesis consists of publications and inventions created by the author that proposed several improvements to the 3G technologies towards the LTE. In the system analysis, the LTE showed by the factor of at least 2.5 to 3 times higher system measures compared to the WCDMA/HSPA reference. The WCDMA/HSPA networks are currently available with over 400 million subscribers and showing increasing growth, in the meanwhile the first LTE roll-outs are scheduled to begin in 2010. Sophisticated 3G LTE mobile devices are expected to appear fluently for all consumer segments in the following years

Digitally fabricated low cost housing: material, joint and prototype

Motivated by the global housing deficit and limited natural resources, this study aims to utilize digital fabrication technologies coupled with local sustainable materials in the quest for alternative, adequate low-cost housing solutions for the less fortunate population, mainly in developing countries. The thesis is structured into two main parts: a theoretical and an empirical study. The theoretical part identifies the research problem and lays the foundation of knowledge, as well as defines the motivating questions, aim, objectives, scope, methodology and tools used throughout the thesis. An overview of fundamental concepts of mechanisation, standardisation, prefabrication, mass housing, and mass customisation is provided. Different types of prefabricated housing are presented followed by a discussion of select architect-led and industry-led early precedents in prefabrication. The theoretical part also includes an analysis of state-of-the-art built projects or prototypes of digitally fabricated houses. Through this analysis, how these prototypes respond to housing problems is addressed and an observation is made of how these built projects can be categorised into main streams or different trends. After defining the potentials and limitations of these precedents, a number of design criteria or design guidelines are proposed forming the basis for the proposition of a housing system that addresses these drawbacks under the name “Housing System 01”. The second part of the thesis is a Design-Build-Evaluate empirical study in which the proposed housing system combining concepts of complete off-site prefabrication with modular parametric localised digital fabrication is outlined. Given the necessity of cost reductions, an integral joining system (snap-fit) using an agricultural residue panel material is tested as the principal method for the construction of wall assemblies. The study proves that by using integral joints, it is possible to involve the end-user of the housing unit in the construction activities promoting the concept of “Self-Build”, as the simplicity of the system allows for the participation of end-users with no previous construction expertise thereby decreasing cost. A set of mechanical tests are performed to characterise wheat straw panels and then snap-fit joints are dimensioned within the elastic limits of this specific material. Three partial wall assembly prototypes are built. One axial compression test is performed on one of the prototypes. The tests show that the material and the joint system promise to provide a viable construction system as an alternative low-cost housing solution. Further optimisation and more physical structural testing are needed to address more complex forces and loading scenarios

Generative Reciprocity: A Computational Approach for Performance-Based and Fabrication-Aware Design of Reciprocal Systems

Using the capabilities of computation and digital fabrication this thesis provides a basis for a novel process of design to fabrication for reciprocal systems. In the traditional sense, reciprocal structures combine the advantages of timber as a renewable source of construction material and low-energy production with the modular fabrication, fabrication efficiency, structural capacities, and elegance of reciprocal interconnection of members. The unique benefits of reciprocal systems come from their discrete geometry, which simplifies the connection detailing and provides freedom for local and global variations in the system. However, this reduction in construction complexity and flexibility of local variation is replaced with geometrical complexity due to numerous compatibility constraints coupled with the structural behavior of the system. This research therefore identifies the key design parameters and design constraints of reciprocal systems. The results demonstrate the complex coupling of geometry, structural performance and fabrication in these systems, hence an essential need for application of an integrative design process. Through the application of computation, simulation, and digital fabrication this research proposes an integrative computational design process which can effectively address the coupling of design, analysis and fabrication of reciprocal systems and accommodate design exploration and optimization. First, a novel computational method for geometric modelling and form-finding is presented to resolve the compatibility constraints and generate the essential geometric and topological data for analysis and fabrication. Second, a flexible and scalable analysis method is implemented to study the interplay of the design parameters and the structural behavior of reciprocal systems. A comprehensive parametric study reveals a complex relationship between the geometric parameters and the structural performance and demonstrates the essential need for a real-time performance feedback for optimal design of free-form reciprocal systems. Third, a generalizable and efficient fabrication process is proposed for reciprocal systems with 3-D module geometry using 5-axis CNC machinery. Towards this goal, four different connection types are proposed, and different fabrication parameters are studied through digital and physical prototyping, destructive structural testing, detailed finite element simulation, and fabrication of a scaled structure. The results are summarized as a guideline for selection of the main fabrication parameters including joint detailing and fabrication tolerances. The computational design process is then developed by rethinking and replacing the conventional direct incremental development by a modular integrative computational process using multi-directional dataflow between different design phases. Finally, the proposed framework is used for a full-scale design to fabrication case study to validate the applicability of the proposed design process.PHDArchitectureUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/155121/1/oliyan_1.pd

The DIRC Particle Identification System for the BABAR Experiment

A new type of ring-imaging Cherenkov detector is being used for hadronic particle identification in the BABAR experiment at the SLAC B Factory (PEP-II). This detector is called DIRC, an acronym for Detection of Internally Reflected Cherenkov (Light). This paper will discuss the construction, operation and performance of the BABAR DIRC in detail

Far-infrared absorption and dispersion studies on methyl iodide solutions

A far-infrared dispersive liquid cell has been developed in collaboration with the National Physical Laboratory. This New Liquid Cell enables both the absorption coefficient and refractive index of a liquid to be accurately determined over the complete far-infrared frequency range. The New Liquid Cell has been used to make dispersive measurements of methyl iodide liquid and methyl iodide in a range of non-polar solvents. These were: carbon disulphide; carbon tetrachloride; n-heptane; n-decane; n-hexadecane and Santotrac 40 (an industrial traction fluid). This data has been combined with microwave measurements, enabling the total orientational correlation functions and the band moments to be determined. Results have also been obtained on the rates of reorientation and static angular correlations of methyl iodide molecules. This information on the liquid dynamics of methyl iodide has been used to elucidate the molecular environment of the solvents using methyl iodide as a probe molecule, which has given evidence for the presence of discrete solute 'pools' within the solvent environment for the longer chain length n-alkanes. Two theoretical models for molecular reorientation have been fitted to the experimental data. The first, a second order truncation of the Mori formalism though giving a good fit to the experimental far-infrared absorption coefficient and refractive index spectra, gave values for the molecular torques that did not agree with measured values. The second, a physically more meaningful model is based on the motion of a molecule which is described by a gaussian distribution of librational frequencies within a molecular cage, gives molecular torque values that agree well with experimental results