Novel disc like molecules based on hexa-n-alkoxy benzoates of triphenylene were synthesised at Hull university. The compounds exhibited thermotropic liquid crystalline behaviour. The compounds differed chemically based upon the number and position of methyl additions to the ester benzoate linkage. Unsymmetrical compounds based on hexa-n-alkoxy triphenylenes were also examined. A number of techniques were employed to observe and measure the physical properties of these compounds. Polarising optical microscopy was used to observe and record the phase behaviour. Typical schlieren nematic textures were often observed in the liquid crystalline phase. The transition temperatures of the phase transitions were recorded to within +/-0.1 °C. Methyl additions to the ester benzoate linkage plays a major role in determining transition temperatures and also the ranges of liquid crystal phase. X-ray diffraction investigations allowed the molecular planar spacings to be measured, use of a heating stage enabled measurements to be taken in the liquid crystalline phase. All the samples produced a diffuse broad diffraction ring in the liquid crystalline phase, indicating that the samples are not highly ordered and that they are likely to have adopted a hexagonal packing arrangement. Planar spacings measured were in the range 22 - 30A, only one sample, DB26, showed a diffraction ring corresponding to a planar spacing of 4.1A, indicating that molecular columns or partial columns were able to form from molecules stacking one on top of another. Thus methyl groups on the ester benzoate linkage disrupt the formation of columns, in turn reducing transition temperatures. A number of methods of successfully aligning the discotic materials using surface treatments are presented. Rubbed PVA and HTAB layers aligned the samples hometropically, while SiO deposited layers aligned the samples homogeneously. (The SiO deposition used an evaporation angle of 45°, a deposition angle of 5° is commonly used to obtain homotropic alignment of calamitic materials.) Methods that produced homogeonous alignment of calamitic materials produced hometropically aligned discotic materials and vice-versa. FTIR allows conformational information about a molecule to be determined. The CH[2] wagging region was investigated to determine conformational information relating to the alkyl arms. Combination of FTIR and aligned samples allowed the alignment process to be investigated, it was determined that the alignment of the molecules occurs in a series of stages, the triphenylene cores align first on cooling, followed by the ester benzoate linkages and finally the alkyl arms. Computer modelling simulations allowed various molecular conformations to be observed, combination with X-ray diffraction data allowed molecular structures to be generated. The software allowed various molecular dimensions to be easily measured and the effect and extent of interdigitation of molecular arms to be observed. The molecular dynamics calculations were only able to calculate energy minimisations for crystalline structures, but the crystalline results offered valuable insights into the liquid crystalline structures and behaviour.

This thesis is focused on a study on modeling and measurement of the indoor radio and infrared channels. Both channels have been studied, compared and their vital differences identified. Initially, an infrared channel model was developed that was not similar to any existing models for the infrared domain. The wireless diffuse infrared channel is solely used indoors and is usually confined within a room. Conventional channel models are described, but their disadvantage is heavy time and processor requirements. A new model is introduced, in which the approach is different from the traditional methods in the way that it discretises the delay range instead of the physical characteristics of the environment. The new model offers accurate results without the increased time and processor requirements compared with traditional techniques. Following the characterisation of the infrared channel, a wideband radio propagation campaign took place in two different buildings that allowed valuable insight into the mobile radio channel. Time domain analysis of the measurement results allowed the careful study of the radio channel and produced interesting results as far as RMS delay spread and Power Delay Statistics are concerned. It has been shown that the RMS delay spread is not always dependent on antenna separation, while it was found to be highly dependent on the clutter present on the measurement environment. The infrared model was finally converted to account for radio propagation. Traditional channel models for indoor propagation prediction are described, while the major differences of the infrared and radio channel are mentioned. The radio channel prediction benefits from the accuracy of the infrared model, where a very high accuracy is necessary in order to predict the effect of scattering. A simple measurement campaign has been introduced in order to validate the results of the simulation tool and a comparison with the most important wideband channel models has been performed, along with higher frequency measurements where scattering is more important. The results present a good fit to the measurements and models in the literature, and empirical conclusions relative to the scattering characteristics of the radio channel are drawn from these comparisons.

Infrared thermography was used to evaluate Carbon Fiber Reinforced Panels (CFRP) and optimize the inspection process so that a set of guidelines can be established in order to be efficient and effective. It has been shown in previous work that when a material is heated up the heat will diffuse through the material at a constant rate. However, if there is a defect in the material, such as a delamination, this defect will act like an insulator. When this happens the heat cannot penetrate as quickly as the rest of the material so the surface above the defect shows up hotter than the rest of the material. An operator looks for inconsistent temperatures in the sample to determine the quality of the piece. Samples with simulated defects were made and modeled using a finite element program. Heat will be applied to the models and the temperature profiles analyzed. Along with changing the heat and time, different post-processing techniques were used to improve the method in determining defects in the sample. Once this has been optimized, actual CFRP with the same simulated defects was experimentally tested using the conditions from the analytical model. The analytical and experimental data was compared to insure that the testing process has been optimized. A standardized process was developed for evaluating the CFRPs using infrared thermography.

Please read the abstract in the section 00front of this document / Dissertation (MEng (Electronic Engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted

Introduction: Process analytical technologies are systems for the analysis and control of manufacturing processes to assure acceptable end-product quality. This is achieved by timely measurements of critical parameters and performance attributes of raw material and in-process material and processes. The introduction of process analytical technology using near infrared analysis was investigated in three areas, namely incoming raw material analysis, blend uniformity analysis and moisture determination in the fluid bed dryer. Methodology: Incoming raw material identification - The FOSS XDS rapid content analyzer was used for the development of a NIR method for the identification and material qualification of starch maize and lactose monohydrate. Blend uniformity analysis – The SP15 Laboratory Blender fitted with near infrared probe was utilized for the study. Two types of blend experiments were designed to monitor the distribution of magnesium stearate (lubricant) in the blend, namely, a powder blend utilizing lactose monohydrate and a granule blend utilizing Ridaq® granule. Software methods were developed to monitor the standard deviation of the absorbance at the wavelengths that were specific for lactose monohydrate, Ridaq® granule and magnesium stearate. To confirm the prediction of end-point using near infrared, results were verified using an atomic absorption method for magnesium stearate. The blends were sampled at the selected time intervals corresponding to three states of the blend, namely, before end-point, at end-point and after end-point using a sampling plan. An additional six blends were conducted for the granule blend and sampled when the standard deviation had reached a value below 3 x 10-6 at the magnesium stearate wavelength at four consecutive data points (standard deviation value extrapolated from blends carried out to predetermined time intervals). Moisture determination in the fluid bed dryer – Moisture values for two products (Product A and Product B) were retrospectively collected from past production batches. A process capability study was conducted on the moisture values to determine if the current process was in a state of control. Results and Discussion: Incoming raw material identification – The algorithms used for the spectral library were able to distinguish between the raw materials selected. The spectral library positively identified the starch maize and lactose monohydrate samples that were not present in the library. The negative challenge with pregelatinised starch and tablettose demonstrated that the spectral library was able to differentiate between closely related compounds. Blend uniformity analysis – Blends sampled at the predetermined time intervals demonstrated a homogeneous state when the standard deviation of the absorbance was low and a non-homogeneous state when the standard deviation of the absorbance was high, thus near infrared prediction on the state of the blend was confirmed by the standard analytical methods. The series of Ridaq® granule and magnesium stearate blends sampled when the standard deviation was below 3 x 10-6 were homogeneous with the exception of one blend that was marginally out of specification. Blend durations were significantly lower than the standard blend durations used in the facility and ranged from 112 to 198 seconds. Moisture determination in the fluid bed dryer – From the process capability study of the two products it was noted that Product A is stable but can still be optimized while Product B is at a desirable state. The statistical evaluation of the moisture values for Product A and Product B demonstrated that the use of the product temperature to monitor the moisture gave consistent results. The current process is stable and capable of producing repeatable results although near infrared provides a means for continuously monitoring the product moisture and allows one to take action to prevent over-drying or under-drying. Conclusion: From the investigations conducted, it can be seen that there is definitely a niche for process analytical technology at this pharmaceutical company. The implementation is a gradual process of change, which may take time, probably several years (Heinze & Hansen 2005).

Although there have been recorded many spectra of dispersions of reactive and unreactive molecules in inert matrices, there has been no real attempt to explain quantitatively the nature of the forces and interactions of these matrices that act on the molecular vibrations of the trapped species. In the present study the infra-red spectra of formaldehyde and water in solid argon and nitrogen matrices and of solid formaldehyde are used as a basis for a discussion and analysis of the conditions that prevail in such matrices. Isotope effects, molecular association, inter-molecular coupling, rotation, the effect of trapping in different lattice positions, and matrix-gas frequency shifts are considered in the Interpretation of the observed spectra. / Science, Faculty of / Chemistry, Department of / Graduate

A number of N-substituted-3-hydroxy-3-phenylphthal-imidines and some of the isomeric amides have been prepared in order to study changes in the infrared spectra of these compounds due to structural changes in the molecule, particularly with reference to a hydroxyl band at 3.0µ and a carbonyl band at 5.75µ.

The present work is a part of a systematic investigation of the frequency shifts in infrared absorption produced by changing to the anions carbonyl containing acidic compounds.

Autonomous firefighting platforms are being developed to support firefighters.  One aspect of this is location of a fire inside a structure.  A multi-spectral sensor platform and fire location algorithm was developed in this research to locate a fire indoors autonomously. The multi-spectral sensor platform used a long wavelength infrared (LWIR) camera and ultraviolet (UV) sensor.  The LWIR camera was chosen for its ability to see through smoke, while the UV sensor was selected for its ability to discriminate between fires and non-fire hot objects.  The fire location algorithm by radiation emission (FLARE) developed in this research used the multi-spectral sensor data to provide the robot heading angle toward the fire. The system was tested in a large-scale structural fire facility.  A series of 20 different scenarios were used to evaluate the robustness of the system including different fuel types, structural features, non-fire hot objects, and potential robot positions within the enclosure.  This demonstrated that FLARE could direct a robot towards the fire regardless of these variables. Directional fire discrimination was added to the platform by limiting the field of view of the UV sensor to that of the LWIR cameras.  Three methods were evaluated to limit the field of view of a UV sensor. These included angled plate housing, bulb cover, and slit opening housing methods. The slit opening housing method was recommended for ease of implementation and size required to limit the field of view of the sensor to the desired value. / Master of Science

Indiana University-Purdue University Indianapolis (IUPUI) / Infrared (IR) polarizers have been widely used in military and commercial applications. Controlling the polarization of incident light is one of major issues in the detector systems. However, conventional polarimetric IR detectors require series of polarizers and optical components, which increase the volume and weight of the system. In this research, stacked 1-dimensional (1-D) subwavelength grating structures were studied to develop compact size IR polarimetric detector by using surface plasmonic polariton. Experimental parameters were optimized by Finite Difference Time Domain (FDTD) simulation. Effects of gold (Au) grating size, numbers of stacked gratings, and dielectric space height were tested in the FDTD study. The fabrication of grating layers was conducted by using nanoimprint lithography. The samples were characterized by scanning electron microscopy. IR transmissions in transverse magnetic (TM) and transverse electric (TE) modes were measured by Fourier transform infrared spectroscopy (FTIR).