Terahertz Technology and Its Applications

The Terahertz frequency range (0.1 – 10)THz has demonstrated to provide many opportunities in prominent research fields such as high-speed communications, biomedicine, sensing, and imaging. This spectral range, lying between electronics and photonics, has been historically known as “terahertz gap” because of the lack of experimental as well as fabrication technologies. However, many efforts are now being carried out worldwide in order improve technology working at this frequency range. This book represents a mechanism to highlight some of the work being done within this range of the electromagnetic spectrum. The topics covered include non-destructive testing, teraherz imaging and sensing, among others

The Solid State Simulation of the Structure and Vibrational Modes of Organic, Hybrid Organometallic and Inorganic Species Using the CRYSTAL09 Code.

An investigation of the structural and vibrational information of organic, hybrid organometallic and inorganic species was conducted using solid-state density functional theory (DFT). In this work the solid state DFT modeling was accomplished using the CRYSTAL09 code to simulate the geometries and vibrational modes of a variety of systems. These studies included: (1) the investigation of three polymorphs of vanadium phosphate, (2) three studies involving the use of 5-(4-pyridyl)tetrazole, and lastly (3) the crystal structure and simulation of α,α,α’,α’-tetrabromo-p-xylene. The studies involving 5-(4-pyridyl)tetrazole are comprised of (a) the comparison of a new polymorph to previously published crystallographic information of the free base 5-(4-pyridyl)tetrazole, (b) the comparison of two hydrohalide salts of 5-(4-pyridyl)tetrazole, and lastly, (c) comparing three isomorphous transition metal complexes with 5-(4-pyridyl)tetrazole as a ligand. In the majority of these systems, with the exception of the polymorphs of vanadium phosphate, terahertz (THz) spectroscopy was used to probe the intermolecular interactions in these molecular crystals. These studies aim to increase the understanding of what effect subtle structural, compositional, or packing differences have on the vibrational normal modes, in particular in the region from 0-100 cm-1 known as the terahertz region. It was found that subtle differences in the structure, composition, or packing could have large and varying effects on the vibrational modes, especially in the terahertz region. In particular, there are no universal trends in the shifting of vibrational frequency; however, the nature of the normal mode has the greatest effect when comparing systems that have compositional differences

59th Annual Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 59th annual meeting of the Rocky Mountain Conference on Magnetic Resonance, co-endorsed by the Colorado Section of the American Chemical Society and the Society for Applied Spectroscopy. Held in Snowbird, Utah, July 22-27, 2018

Investigating biomedical applications with terahertz pulsed imaging in reflection geometry.

Sy, Ming Yiu.Thesis (M.Phil.)--Chinese University of Hong Kong, 2011.Includes bibliographical references (p. 95-100).Abstracts in English and Chinese.Abstract --- p.1Acknowledgments --- p.5List of figures --- p.9List of tables --- p.13List of abbreviations --- p.14List of publications and awards --- p.15Awards --- p.16Chapter Chapter 1 --- Introduction --- p.17Chapter 1.1 --- Terahertz radiation --- p.18Chapter 1.1.1 --- Terahertz sources --- p.19Chapter 1.1.2 --- Terahertz systems --- p.20Chapter 1.1.3 --- Reflection and Transmission geometries --- p.21Chapter 1.2 --- Terahertz biomedical applications --- p.24Chapter 1.2.1 --- Biomolecules --- p.24Chapter 1.2.2 --- THz biomedical imaging --- p.25Chapter 1.2.3 --- THz Spectroscopy --- p.26Chapter 1.3 --- Objectives --- p.26Chapter 1.4 --- Structure of this thesis --- p.26Chapter Chapter 2 --- Theory and experimental system --- p.28Chapter 2.1 --- Theory --- p.28Chapter 2.1.1 --- Propagation of electromagnetic field through dielectric media --- p.29Chapter 2.1.2 --- A de-noising method --- p.32Chapter 2.1.3 --- Baseline calculation --- p.34Chapter 2.1.4 --- Frequency-dependent Refractive Index and Absorption Coefficient.. --- p.37Chapter 2.2 --- Experimental Configuration --- p.41Chapter 2.2.1 --- Terahertz generation and detection --- p.41Chapter 2.2.2 --- Configuration of our system --- p.44Chapter 2.2.3 --- Hand-held TPI Setup --- p.46Chapter 2.3 --- Data Structure --- p.48Chapter 2.4 --- Pre-processing and the user interface --- p.49Chapter 2.4.1 --- Data pre-processing 1 (Chopping) --- p.49Chapter 2.4.2 --- Data pre-processing 2 (Angle selection) --- p.50Chapter 2.4.3 --- The user interface for the data processing --- p.52Chapter Chapter 3 --- Ex-v/vo experiment: investigating the origin of contrast --- p.54Chapter 3.1 --- Liver Cirrhosis --- p.54Chapter 3.1.1 --- Liver --- p.54Chapter 3.1.2 --- Liver cirrhosis --- p.54Chapter 3.1.3 --- The trend of liver cirrhosis --- p.56Chapter 3.1.4 --- Technique for diagnosing liver cirrhosis --- p.57Chapter 3.2 --- Experiment protocol --- p.58Chapter 3.2.1 --- Formalin fixing --- p.58Chapter 3.2.2 --- Sample preparation --- p.58Chapter 3.2.3 --- Formalin fixing protocol --- p.60Chapter 3.2.4 --- Histopathology --- p.61Chapter 3.2.5 --- Protocol for measuring sample water content --- p.61Chapter 3.3 --- Results and discussion --- p.62Chapter 3.3.1 --- Optical parameters of the fresh and fixed samples --- p.62Chapter 3.3.2 --- Consistency with previous results --- p.63Chapter 3.3.3 --- The relationship between water content and optical parameters --- p.64Chapter 3.3.4 --- Conclusion --- p.68Chapter Chapter 4 --- In-vivo experiment: imaging of human skin --- p.69Chapter 4.1 --- Human skin --- p.69Chapter 4.1.1 --- The structure of human skin --- p.69Chapter 4.1.2 --- Skin thickness --- p.70Chapter 4.1.3 --- The structure and regeneration of stratum corneum --- p.70Chapter 4.1.4 --- Stratum corneum related Skin disease --- p.72Chapter 4.2 --- Combing reflections of electromagnetic wave --- p.73Chapter 4.3 --- Experiment protocol --- p.74Chapter 4.3.1 --- THz response of human skin --- p.74Chapter 4.3.2 --- Protocol for measuring human skin --- p.75Chapter 4.4 --- Results and discussion --- p.76Chapter 4.4.1 --- The variation due to the position --- p.76Chapter 4.4.2 --- The variation due to the temperature and humidity --- p.78Chapter 4.4.3 --- Discussion --- p.79Chapter Chapter 5 --- Noise evaluation --- p.80Chapter 5.1 --- The main noise source --- p.80Chapter 5.2 --- SNR and DR --- p.80Chapter 5.2.1 --- Signal to noise ratio (SNR) --- p.80Chapter 5.2.2 --- Dynamic range (DR) --- p.81Chapter 5.2.3 --- SNRVS DR --- p.82Chapter 5.3 --- Simulation of noise impact on the complex refractive index --- p.83Chapter 5.3.1 --- Methodology --- p.83Chapter 5.3.2 --- SNR: Simulation results and discussions --- p.85Chapter 5.3.3 --- DR: Simulation results and discussions --- p.87Chapter 5.3.4 --- Conclusion --- p.89Chapter Chapter 6 --- Conclusion and future work --- p.90Chapter 6.1 --- Conclusion --- p.90Chapter 6.1.1 --- A summary of Terahertz pulsed imaging (TPI) techniques --- p.90Chapter 6.1.2 --- Our system and calculations --- p.90Chapter 6.1.3 --- Terahertz spectroscopy of liver cirrhosis: investigating the origin of contrast --- p.91Chapter 6.1.4 --- In-v/vo study: skin measurement --- p.91Chapter 6.1.5 --- SNR sensitivity --- p.92Chapter 6.2 --- Suggestions for future work --- p.92Chapter 6.2.1 --- Algorithms --- p.92Chapter 6.2.2 --- Understanding the origin of contrast --- p.93Chapter 6.2.3 --- Application in cardiovascular diagnosing imaging --- p.93Chapter 6.3 --- Concluding remarks --- p.94References --- p.9

A Comprehensive Review on Process and Technological Aspects of Wood-Plastic Composites

This review deals with recent works on the process and technological aspects of wood-plastic composites (WPCs) manufacturing.WPCs relate to any composites that are built from wood and non-wood fibers and thermoplastic polymers. Recent progress relevant to wood-plastic composites has been reviewed in this article. The process and technological aspects of WPC, such as raw materials, fabrication, mechanical, physical, thermal, and morphological properties, were outlined comprehensively. The manufacturing process of WPCs is an important aspect of WPCs production. Manufacturing methods like compression molding and pultrusion have some limitations. Extrusion and injection molding processes are the most widely used in WPCs due to their effectiveness. Recent developments dealing with WPCs and the use of different kinds of nanofillers in WPCs have also been presented and discussed. Nanoclays are widely used as nanofillers in WPCs because they represent an eco-friendly, readily available in large quantity, and inexpensive filler. WPCs can be found in a wide range of applications from construction to the automotive industry.Keywords: additive manufacturing, adhesion, fabrication techniques, mechanical and physical properties, wood-plastic composite

Radio frequency non-destructive testing and evaluation of defects under insulation

PhD ThesisThe use of insulation such as paint coatings has grown rapidly over the past decades. However, defects and corrosion under insulation (CUI) still present challenges for current non-destructive testing and evaluation (NDT&E) techniques. One of such challenges is the large lift-off introduced by thick insulation layer. Inaccessibility due to insulation leads corrosion and defects to be undetected, which can lead to catastrophic failure. Furthermore, lift-off effects due to the insulation layers reduce the sensitivities. The limitations of existing NDT&E techniques heighten the need for novel approaches to the characterisation of corrosion and defects under insulation. This research project is conducted in collaboration with International Paint®, and a radio frequency non-destructive evaluation for monitoring structural condition is proposed. High frequency (HF) passive RFID in conjunction with microwave NDT is proposed for monitoring and imaging under insulation. The small-size, battery-free and cost-efficient nature of RFID makes it attractive for long-term condition monitoring. To overcome the limitations of RFID-based sensing system such as effective monitoring area and lift-off tolerance, microwave NDT is proposed for the imaging of larger areas under thick insulation layers. Experimental studies are carried out in conjunction with specially designed mild steel sample sets to demonstrate the detection capabilities of the proposed systems. The contributions of this research can be summarised as follows. Corrosion detection using HF passive RFID-based sensing and microwave NDT is demonstrated in experimental feasibility studies considering variance in surface roughness, conductivity and permeability. The lift-off effects introduced by insulation layers are reduced by applying feature extraction with principal component analysis and non-negative matrix factorisation. The problem of thick insulation layers is overcome by employing a linear sweep frequency with PCA to improve the sensitivity and resolution of microwave NDT-based imaging. Finally, the merits of microwave NDT are identified for imaging defects under thick insulation in a realistic test scenario. In conclusion, HF passive RFID can be adapted for long term corrosion monitoring of steel under insulation, but sensing area and lift-off tolerance are limited. In contrast, the microwave NDT&E has shown greater potential and capability for monitoring corrosion and defects under insulation