Dissertations / Theses on the topic 'Light tube'

STACEE (Solar Tower Atmospheric Cerenkov Effect Experiment) is a ground-based gamma-ray telescope. Using a large array of mirrors from a solar heliostat facility to capture Cerenkov light from gamma-ray showers in the atmosphere, STACEE plans to lower the threshold available to ground-based gamma-ray telescopes. Determining the threshold of STACEE is reliant upon understanding the components of the telescope. The photomultiplier tubes used to convert the Cerenkov light to electronic signals need to be carefully characterized as a part of this process. We describe a method to determine the gain of the photomultiplier tubes using an uncalibrated light source. Using a statistical model, the output distribution of a photomultiplier tube with a fixed-amplitude, pulsed light source can be used to determine the gain.

Daylight penetration into a deep interior space can be achieved by using a light tube strategy. This research investigates how effective a room's ceiling cavity can be as a daylight transporting system. The design, therefore, tries to answer the question "What is the optimal geometry for a ceiling cavity and inlet aperture to bring deeper daylight penetration and achieve a higher illumination level, measured at the back of a room, than that achieved by a typical high window opening?" Corporate affiliate 3M assisted this project by providing a prismatic and highly specular surface to cover the underlying geometry of the ceiling cavity. A 16' deep room section with a high window opening on one side was constructed as a test cell. Inside, sensors were set up to allow light measurement at task level along the depth of the room. Light rays were deflected by the geometry of the ceiling cavity, through a number of internal reflections on the highly reflective film surface, to a diffuser at the back. The three most promising geometric designs from scaled model tests were selected, installed and tested for efficiency in the full-scale test cell.
Master of Science

This thesis deals with the measurement of light tubes efficiency in laboratory conditions during lighting by almost direct light rays. It also deals with the measurement of the spectral reflectance of the reflective materials available on the Czech market. The comparison of the efficiency of different light routes and also the determination of the spectral qualities of different reflective materials are the aims of this thesis. The light tubes were measured by means of the cubic integrator. The light source was moved and manoeuvred by means of the automatic goniophotometer. The light source flow was determined by the method of the zonal flows. The data were calculated in the Matlab programme. The evaluation is both in the graphic and in the numeric forms. The result of the thesis is both the comparison of the reflective materials for light tubes qualities, and the evaluation of efficiency of the assigned light routes. The optimal variant can be then selected during designing of the light tubes route according to the results of the measurements.

Most of the research on high strain rate effects on wood since the 1950s has been on impact loading. Very limited work has been conducted on full-scale wood specimens under blast loading. In North America, the prevalence of these structures makes them susceptible to unintended blast effects. The question on how to retrofit and protect these structures against blast loads has still not been addressed adequately, and design provisions for new wood structures against blast are not comprehensive. Far-field explosion effects were simulated using the University of Ottawa shock tube. Twenty-five light-frame wood stud walls were tested dynamically. The research program aimed to determine the response of light-frame wood stud walls to blast loads that correspond to the heavy to blow-out damage levels. The results showed that, under idealized simply supported end conditions, the stud walls failed in flexure. Under heavier loads, ripping of sheathing commonly used in light-frame wood structures was observed, which caused premature failure of the assembly because the load was not fully distributed to the studs. The use of stiffer sheathing or reinforcing the sheathing provided a better load path and the wall was capable of reaching its full capacity. The effect of using realistic boundary connection details was investigated, and the results showed that typical connection detailing performed poorly under blast loads. Designed steel brackets connecting the studs to the rim-joist allowed for the studs to reach their full capacity. An analytical single degree-of-freedom model was generated using material properties obtained from static testing. The model was validated using the experimental results from the shock tube testing. Also, a catcher system consisting of welded-wire-mesh was incorporated into the wall system in order to diminish debris throw.

Deliberate and accidental explosions along with the heightened risk of loss of life and property damage during such events have highlighted the need for research in the behaviour of materials under high strain rates. Where an extensive body of research is available on steel and concrete structures, little to no details on how to address the design or retrofitting of wood structures subjected to a blast threat are available. Studies reported in the literature that focused on full scale light-frame wood structures did not quantify the increase in capacity due to the dynamic loading while the studies that did quantify the increase mostly stems from small clear specimens that are not representative of the behaviour of structural size members with defects. Tests on larger-scale specimens have mostly focused on the material properties and not the structural behaviour of subsystems. Advancements in design and construction techniques have greatly contributed to the emergence of taller and safer wood structures which increase potential for blast threat. This thesis presents results on the flexural behaviour of light-frame wood stud walls subjected to shock wave loading using the University of Ottawa shock tube. The emphasis is on the overall behaviour of the wall subsystem, especially the interaction between the sheathing and the studs through the nailed connection. The approach employed in this experimental program was holistic, where the specimens were investigated at the component and the subsystem levels. Twenty walls consisting of 38 mm x 140 mm machine stress-rated (MSR) studs spaced 406 mm on center and sheathed with two different types and sheathing thicknesses were tested to failure under static and dynamic loads. The experimental results were used to determine dynamic increase factors (DIFs) and a material predictive model was validated using experimental data. The implications of the code are also discussed and compared to the experimental data. Once validated, an equivalent single-degree-of-freedom (SDOF) model incorporating partial composite action was used to evaluate current analysis and design assumptions. The results showed that a shock tube can effectively be used to generate high strain-rate flexural response in wood members and that the material predictive model was found suitable to effectively predict the displacement resulting from shock wave loading. Furthermore, it was found that current analysis and design approaches overestimated the wall displacements.

Since the invention of Laser (in 1960) and low loss optical fiber (in 1966) [1], extensive research in fiber-optic sensing technology has made it a well-defined and matured field [1]. The measurement of physical parameters (such as temperature and pressure) in extremely harsh environment is one of the most intriguing challenges of this field, and is highly valued in the automobile industry, aerospace research, industrial process monitoring, etc. [2]. Although the semiconductor based sensors can operate at around 500oC, sapphire fiber sensors were demonstrated at even higher temperatures [3]. In this research, a novel sensor structure is proposed that can measure both pressure and temperature simultaneously. This work effort consists of design, fabrication, calibration, and laboratory testing of a novel structured temperature compensated pressure sensor. The aim of this research is to demonstrate an accurate temperature measurement, and pressure measurement using a composite Fabry-Perot interferometer. One interferometer measures the temperature and the other accurately measures pressure after temperature compensation using the temperature data from the first sensor.
Master of Science

Poor water quality is a global health concern affecting one billion people around the world. It is important to monitor water sources in order to maintain the quality of our drinking water and to avoid disease outbreaks. Targeting Escherichia coli as a faecal indicator is a widely used procedure, but the current methods are time consuming and not adequate to prevent spreading of faecal influence.   This Master thesis demonstrates the development of a near infrared fluorescence flow cytometer sensor system targeting Escherichia coli, using fluorescently labeled chicken IgY antibodies. The near infrared light was chosen to avoid fluorescence from blue-green algae that are present in the water source.   The hardware was developed with a 785  nm laser line to detect Alexa Fluor 790 labeled antibodies, using a photomultiplier tube or two different CMOS cameras. The antibodies were labeled using a commercial labeling kit, and evaluated using antibody binding assays and the developed hardware.   The IgY antibodies were successfully labeled with Alexa Fluor 790 and the function was maintained after the labeling process. The result demonstrates the principles of the sensor system and how it solved to the problem with fluorescence from blue-green algae. An aperture was used to overcome the suboptimal laser and filter setup, and to increase the sensitivity of the system. However, only a small fraction of the cells could be detected, due to challenges with the focal depth and loss of sensitivity in the photomultiplier tube at near infrared wavelengths. Further development is required to create a working product.

This thesis deals with the illuminance space through light guide. It describes it's basic principles, technical features and ways of differentiation between the technologies. The thesis also includes latest methods for evaluation of illumination of space supported by various computer simulations.

This work is focused on exploring a unique integration of techniques, Raman micro-spectroscopy and atomic force microscopy (AFM), which when combined offer more than the sum of their respective parts. The non-invasive chemical specificity afforded by Raman spectroscopy, combined with the nanoscale-resolution topographic imaging of AFM offer much individually. The physics underlying the practical application of each technique is very general; Raman spectroscopy detects molecular vibrational shifts using light, and AFM uses a physical probe to interact with a surface to provide topographic (and mechanical) information. As a result, there are few restrictions to the possible samples that can be studied with these techniques, from semiconductors and geological crystals, through to simple organic chemical structures all the way to complex biological molecules and systems such as cells and tissue. In this work, a synthetic biomaterial composed of diphenylalanine (FF) peptide units which self-assemble into strong tubular structures is used as a sample of interest when exploring the different possibilities available from a combined Raman-AFM instrument. First, the combined system was set up in order to perform tip-enhanced Raman spectroscopy (TERS), a technique promising Raman spectroscopic imaging at the resolution of AFM imaging. A relatively young technique, TERS has huge potential in extending the reach of Raman spectroscopic imaging to the nanoscale, at a regime where a great deal of structure exists, but is usually blurred by conventional diffraction-limited Raman microspectroscopy. A major focus in this work is addressing a current problem with TERS: the fabrication of suitable probes. TERS typically utilizes AFM tips modified to have a silver nanoparticle, capable of locally enhancing the Raman signal, attached at the probe apex. A new method is presented here that promises several improvements over existing approaches, as the entire fabrication can be performed in-situ on the instrument. Tips produced in this way are then characterized by electron microscopy and tested on FF nanotubes. Following this, several techniques for the synthesis of silver nanoparticles are explored for use in TERS. Here, the focus is particularly on decahedral nanoparticles, which can be grown into rod shaped particles with well- defined shapes and sizes. These are important considerations for obtaining the desired enhancing properties for TERS probes. Finally, the AFM-Raman instrument is used to investigate the mechanical properties of FF tubes using several methods. AFM force spectroscopy of tubes suspended across a gap can be used in conjunction with a bending beam theory to measure the Young's modulus of individual tubes. A new type of co-localized experiment using polarized Raman spectroscopy on a suspended tube under various forces from the AFM is tested, and subsequently information relating to the hydrogen bonding network is used, in conjunction with existing X-ray data, to determine the molecular contributions to the modulus using a simple model for amyloid fibrils. Each experiment operates at the single fibril level, with the same fibrils being used, such that different methods can be compared for a single FF tube.

Augalo derlingumo didinimas ir derliaus kokybės gerinimas – vienas iš svarbiausių žemės ūkio mokslų prioritetų. Valgomoji bulvė (Solanum tuberosum L.) – svarbus maisti-nis augalas, kurio auginimo ir paplitimo geografija didesnė nei kukurūzų, ryžių ir kviečių. Pagrindinė bulvių produkcija – stiebagumbiai, kurie naudojami ne tik maistui, pašarui, bet ir alternatyviems tikslams: bioplastikų, krakmolo, spirito gamybai (Šlapakauskas, Du-chovskis, 2008). Bulvių pasėlio augimas labai priklauso nuo sėklai naudojamų stiebagumbių koky-bės. Pagal fiziologiją bulvė sudėtingas augalas, kurio augimo, vystymosi bei stiebagumbių laikymo sąlygos įtakoja jų dygimą (Cristiansen et al., 2006). Bulvių stiebagumbių dygi-mas – vienas iš svarbiausių veiksnių, nulemiančių kero stiebų skaičių, kurie yra derlių įtakojantis faktorius (Allen et al., 1992). Siekiant paankstinti derlių, suformuoti tankų, produktyvų pasėlį stiebagumbių daigi-nimui gali būti naudojami egzogeniniai augimo reguliatoriai – sintetiniai fitohormonų analogai, kurie leidžia pakeisti augalo hormonų statusą, modifikuoti metabolizmo proce-sus. J. Lazauskas (2001) teigia, kad geriausia bulves daiginti natūraliomis šviesos sąlygo-mis, ne aukštesnėje nei 17 oC temperatūroje, 35–45 dienas iki sodinimo, tuomet jų daigai būna trumpi ir stiprūs. Tačiau kai stiebagumbių daiginimo metu trūksta šviesos ar būna netinkama temperatūra, pumpurai būna ne vienodo dydžio, silpni. Mokslininkai plačiai tiria abiotinių veiksnių (šviesos, temperatūros)... [toliau žr. visą tekstą]
Research problem. Plant productivity enhancement and yield quality improvement are one of the top priorities for agricultural sciences. The potato (Solanum tuberosum L.) is a staple crop, whose cultivation and distribution geography is larger than that of maize, rice and wheat. The main potato produce is tubers which are used not only for food and feed but also for alternative purposes – production of bioplastics, starch and spirits (Šlapakauskas, Duchovskis, 2008). Potato crop performance is highly reliant on the quality of tubers used as seed material. In terms of physiology, the potato is a complex plant whose growth, development and tuber storage conditions influence sprouting (Cristiansen et al., 2006). Potato tuber sprouting is one of the prime factors determining the number of stems per potato plant, which is also a factor, which influences potato yield (Allen et al., 1992). Seeking to advance potato maturity and harvesting and to achieve a dense, productive stand, exogenous growth regulators can be used for tuber sprouting. These growth regulators are synthetic analogues of phytohormones that enable changes in plant hormonal status and modification of metabolic processes. J. Lazauskas (2001) suggests that to achieve short and strong sprouts, it is most efficient to sprout potato tubers under natural light conditions at a temperature no higher than 17 oC, 35–45 days prior to planting. However, a shortage of light during tuber sprouting or inadequate temperature result... [to full text]

In a worldwide pursuit for more Accident Tolerant nuclear Fuel (ATF), the quest to obtain and certify alternative nuclear fuel cladding tubes for light-water nuclear power reactors is still a key challenge. One of the facets in this program to develop more ATF is the heat transfer evaluation between the various proposed clad tubes manufactured from suitable replacement materials and the current problematic zirconium-alloy based clad tubes used in nuclear power reactors. For the heat transfer analysis, the accurate measurement of the temperature on the heat transfer surface of heated tubes to be tested was one of the important objectives for the effective analysis of the heat transfer characteristics to the water coolant. After extensive investigations, a suitable technique was developed and validated against recognised forced-convection heat transfer correlations. The results showed that this technique was well suited for external forced convection heat transfer studies from heated surfaces exposed to forced convection water coolants.
Dissertation (MSc)--University of Pretoria, 2019.
Mechanical and Aeronautical Engineering
MSc (Applied Science - Mechanics)
Unrestricted

The goal of this diploma’s thesis is to inform about present development of light sources, new technologies and about achieved parameters of these light sources. The thesis is mainly directed to describe efficiency of transformation electric energy to light at single types of light sources. There are described the concrete technical parameters of sources quoted by manufacturers and the contructional solution of single types of light sources. There is created a graphic comparation of electrotechnical and light parameters of the light sources.

碩士
東海大學
工業工程與經營資訊學系
94
Among the display industry, one of the major investment targets of Taiwanese government at the present, the back light unit manufacturing is the most important downstream sector. Carbon Nano-tube Back Light Unit (CNT-BLU) is a highly potential product which can be used as the back light source in place of the current back light unit for display product. Until now, the development of CNT-BLU is still in the research and development stage. Therefore, the production of CNT-BLU encounters various process problems that are detected by engineers based on their experience. The processes of determining the causes of the manufacturing process problems usually take considerable time and cost in the R&D stage. This study constructs a CNT-BLU manufacturing process problem analysis model on the basis of failure mode and effect analysis (FMEA) which integrates the techniques of the fault tree analysis (FTA), cause and effect diagram, fuzzy Delphi and fuzzy inference. This study extensively reviews the literature related to the current problems of manufacturing process and showed the validity of the proposed model. After conducting a real-world case comparison, we find that the differences between the analytic result and the actual result are insignificant. From the results of this study, the capability of conducting process problem analysis of this model has been justified. The model also provides a useful tool for those who are interested in the analysis of CNT-BLU manufacturing process problems.

碩士
明志科技大學
電子工程研究所
102
Carbon reduction proceed from everyday life is an inevitable trend is also the subject of an important project. In practice, in addition to the general public when we do a dress up of LED energy-saving lamps, electronic of research and development related to the production staff also need to study more with constant diligence and investigate from the design. 　　The purposes of this study, we will do for traditional Buck - Switching power circuit with non-use electrolytic capacitors and then to enhance the power life. We will use the classic AC-DC Driver IC-9910 and use the external DC control function. After the circuit divides, keep the output and input to synchronization and then enhance the power factor. Then applied to the power supply design for LED T8 light tube, at the same time we will meet the LED lamp regulatory requirements of the Energy Star

碩士
國立中興大學
材料科學與工程學系所
100
Layered double hydroxide (LDH) nanostructure film with highly oriented have been fabricated on inert substrate such as AEBE glass and InGaN-based light-emitting diodes by one-step, room-temperature process, in which the chemical formula of the oriented ultrathin film is Li2Al4(CO3)(OH)12．mH2O confirmed by GAXRD. This study simply immersed the tablet-shaped specimen lying flat in a aqueous alkaline Al3+- and Li+ -containing solution. The solution was prepared by dissolving AlLi intermetallic compound (IMC) in distilled water. This method is simple, rapid, and may be readily extended to some other inert substrate. As an example, Li-Al-CO3 LDH thin film was coated on AEBA glass in only 40 minutes, the treated specimen demonstrates almost 100 % transparency to visible light and exhibits UV shielding ability in UV-B to UV-C region (minimum about 85 % UV transparency). In another case, nano-scale Li-Al LDH-covered InGaN-based LEDs has been realized in only 30 minutes, that the light output power of the LDH (thin)-LED had a 31.2 % enhancement at 20-mA operating current, compared to standard InGaN-based LEDs (ST-LEDs). After calcinating the as-grown Li-Al LDH film (via hanging method) at high temperature (600 ℃) for 12 hours, a LiAlO2/γ-Al2O3 porous micro-sheet film was obtained on porous 316L stainless steel tube, in which the porous oxide film offers a application possibilities to be a intermetallic diffusion barrier.

碩士
國防大學理工學院
材料科學與工程碩士班
103
Optimization of anode for field emission tube (FET) was studied in this thesis. The study of this thesis contains three sections. The first section mainly focuses on development of the fabrication process for FET anode. Different types of conductive layers were prepared for the transmissive and reflective FET respectively. The results indicate that the annealing atmosphere and temperature would affect the quality of the conductive layers. Also, the ratio of phosphor slurry was improved to enhance the uniformity of the phosphor layer. The second section investigated the influence of different modification on the light-emitting efficiency of ZnS phosphor. The ZnS phosphor powders were modified with ultrasonic vibration or ball milling and then thermally annealed to reduce defects from the modification process. The third section of this thesis combined the anode conductive layer prepared from the optimal parameters with the modified ZnS phosphor to prepare field emission anode. The results of field emission test, the spectrum and lighting efficiency were compared with those of anode prepared from unmodified ZnS phosphor. The results show that the illumination performance of FETs with modified ZnS phosphor was 38% higher than those from unmodified phosphor.

Bile acids are physiologically important metabolites, which are synthesized in liver as the end products of cholesterol metabolism and then secreted into the intestines. They play a critical role in the digestion and absorption of fats and fat-soluble vitamins through emulsifications. The amphipathic and chiral nature of bile acids makes their unique building blocks for assembling supramolecular structures including vesicles, fibers, ribbons and hollow tubes. Lithocholic acid (LCA) is a secondary bile acid. Our studies show LCA can self-assemble into helical tubes in aqueous solution by the linear aggregation and fusion of vesicles. The objective of this dissertation is to tune the structure of helical tubes and functionalize them by the co-assembly of ionic LCA and cationic cetyltrimethylammonium bromide (CTAB) and ionic LCA and cationic cyanine dye (CD), respectively. The first part of this dissertation focuses on the ionic-assembly of LCA and CTAB to synthesize the helical tubes with varied diameters and pitches. Our studies show that LCA and CTAB can self-assemble into helical tubes in NH4OH aqueous solution. The diameter of the helical tubes can be changed by adjusting the molar ratio of LCA and CTAB. The pitch of the helical tubes can be tuned by varying NH4OH concentrations. Differential scanning calorimetry studies indicate that there is a homogeneous composition distribution in the LCA/CTAB helical tubes. X-ray diffraction analysis studies show that the helical tubes have multibilayer walls with an average d-spacing of 4.11nm. We demonstrate that the helical tubes with varied diameters and pitches can be transformed into helical silica through the sol-gel transcription of tetraethoxysilane (TEOS). The second part of this dissertation is to use the ionic self-assembly of LCA and CD to design light-harvesting tubes by mimicking green sulfur bacteria that are known to be a highly efficient photosynthesizer. X-ray diffraction and optical spectra show that LCA and CD can co-assemble into J- or H-aggregate tubes, depending the condition under which the self-assembly occurs. We demonstrate the feasibility of using the J-aggregate nanotubes in the sensitive and selective detection of mercury (II) ions by the photoinduced electron transfer under sunlight. The presence of mercury (II) ions in aqueous solution could be detected for concentrations as low as 10 pM.
Ph.D.
Doctorate
Materials Science Engineering
Engineering and Computer Science
Materials Science and Engineering

碩士
國立中央大學
企業管理學系碩士在職專班
98
Due to the high market price, it is hard to promote LED tubes nowadays. The market price of LED tubes is 17.5 times than that of fluorescent tubes. Although the advantages of LED tubes are energy saving and eco-friendly, it doesn’t help to earn a high market price. Normally, a total new product （disruptive innovation） takes time to phase in the market because no one know the product in the beginning stage. Or even end users know the products but are not familiar with theirs advantages. Or end uses know the advantages of the products very well, but can’t afford to pay such a price. LED tubes are facing the high market price issue and can’t cross the chasm between Market introduction stage and Growth stage. In accounting, fluorescent tubes belong to expense account. However, the life span of LED tubes is almost 50,000 hours. After studying definition of Accounting, law or government regulations, LED tubes can belong to asset account. Due to this change of cost behavior, for enterprises, the loan can be collateralized by LED tubes and then the fund dispatching can be more flexible. The purchase decision of LED tubes should be complex. Buyers should consider the total cost, included products performance, durable time and saving energy cost, not the market price only. For the business model of LED tubes, the lump sum, installment or lease all can execute well. However in buyer views, if for the long period project, the installment model is the best choice. If for the short period project, the lease should be the best choice. In seller views, whether the project is for long or short period, the lease model is the best choice. Usually innovations are hard to cross the chasm because of the high market price. If we modify our business model to lease, all innovations can have opportunities to enlarge the market share.

博士
國立清華大學
化學系
94
Abstract Conjugated polymers are organic semiconductors and, as such, are of great potential importance for device fabrication. Such devices include light-emitting diodes, light emitting electrochemical cells, photovoltaic cells, thin-film transistors, and plastic lasers. The discovery of electroluminescence in conjugated polymers gave an impetus to the development of light emitting devices for display technology. New monosubstituted poly(phenylacetylene)s (PPAs) P1-P6 were synthesized by using the transition metal catalyst WCl6 and organometallic cocatalyst Et3SiH in toluene at rt in good yields. The polymers produced were brown to dark purple solids and soluble in organic solvents such as toluene, chloroform, dichloromethane, THF, xylene etc. The weight-average molecular weight (Mw) was ranging from 4 × 104 to 5 × 105. IR and NMR studies confirmed the structure of the polymers. The stereo structure of the polymers was confirmed by 1H NMR and it can be concluded that WCl6 produces trans-rich polymers together with less than 10% cis-rich polymers. The polymers were found by TGA studies to begin losing weight at ca. 350 ℃ under nitrogen, which shows that P1-P6 are thermally more stable than poly(phenyl acetylene) (PPA). UV-visible spectra of P1-P6 showed large red-shifted absorption maximum as compared with that of PPA. The fluorescence spectra of polymers P1, P4, P5 and P6 showed blue emission (~414 nm), while P2 and P3 showed purple emission upon excitation of their THF solution. A new disubstituted polyacetylene was synthesized with the transition metal catalyst NbCl5 with the cocatalyst n-Bu4Sn in toluene at RT in good yield. The polymer was bright fluorescent yellow color solid with an Mw of ca. 2.8 × 105. The polymer was found to be highly soluble in most of the organic solvents such as toluene, chloroform, dichloromethane, THF, xylene etc. The structure of the polymer was confirmed by spectroscopic analysis such as NMR and IR. The polymer was thermally stable due to the presence of phenylethynyl group at the para-position, which showed 5% weight loss at about 386 ℃. The polymer showed absorption maximum at ca. 292 nm and the photoluminescence showed blue-green emission upon excitation at their absorption maximum in THF solution. Solid state absorption and emission showed no aggregation, due to the steric hindrance of the tolane and hexyl group on the polymer backbone. The optical and thermal properties of the polymer PhPO were found to be much better than the parent polymer PPhA-6. A series of new poly(phenylene ethynylene) homopolymers (PE-1 and PE-2) copolymers (PE-3 to PE-7), with phenyl, fluorene, carbazole and pyrene units, were synthesized by the Pd catalyzed coupling reaction in good yields. The structures of the polymers were confirmed by IR and NMR spectroscopies and their weight average molecular weights were measured by GPC in THF eluent. The polymers in general showed the temperature of 5% weight loss appeared at ca. 281-358 ℃. The polymers exhibited emission in blue region and blue-green-light in THF solution upon excitation at their absorption maximum. Due to aggregate formation, polymers showed red-shifted absorptions and emissions in their solid state films as compared with their solutions. Solvent-induced aggregation of PE-1 and PE-2 showed strong polymer chain interaction both in absorption and emission spectra. While the solvent-induced aggregation of polymers PE-3, PE-5, and PE-6 showed strong polymer chain interaction in the emission spectra and weak polymer chain interaction in the absorption spectra. Interestingly the solvent-induced aggregation of PE-4 and PE-7 showed very weak polymer chain interaction in both absorption and emission spectra. We have synthesized various oligo(phenylene ethynylene)s (OPEs) by Pd catalyzed coupling reaction with good yields, in which alkyl and alkoxy groups were introduced as side chains and fluorene, carbazole and pyrene were introduced as alternating aryl units in their chromophoric chain. The oligomers are highly soluble in most of the organic solvents such as chloroform, toluene, ethyl acetate, THF, dichloromethane, DMSO, DMF etc. The structure of the oligomers was confirmed by means of various spectroscopic analyses. The oligomers in general showed the weight loss temperature of 5% appeared at ca. 312-485 ℃, and the weight retention at 900 ℃ was much higher, i.e., 80 to 40%. The thermal properties of oligomers showed liquid crystalline phases for OPE-5 and OPE-11 and they showed nematic schlieren textures, while OPE-6 showed smectic focal conic textures upon cross-polarized optical microscope observation. The solid state film of oligomers showed red-shifted emission and absorption from their solution spectra due to aggregate formation in the solid state. Finally, we have synthesized polymer nanotubes and carbon nanotubes using the poly(phenylene ethynylene)s of PE-3 and PE-6 using alumina membrane template with an average pore size diameter of ca. ~200 nm. The carbon nanotubes were prepared by heating the alumina membrane template containing the polymer tube nanostructures at 700 ℃. By this template nanostructuring method, both polymer nanotubes and carbon nanotubes were formed with a very good mechanical strength. The tubes are circular hollow and the surface was very smooth. After complete removal of the alumina membrane, the average outer diameter of polymer nanotubes and carbon nanotubes were in well agreement with the pore diameter (~200 nm) of alumina membrane template. The carbon nanotubes prepared from polymer PE-6 at 700 ℃ are turbostatic in nature.

Omnipresence of heterogeneity is conspicuous in all creations of nature. Heterogeneity manifests itself in many forms at different scales, both in time and space. Engineering domain being an exotic fusion of human creativity and ever-increasing demands exemplifies the ubiquity of heterogeneity. Surprisingly, the plethora of materials we see around seem to stem from myriad combination of few base materials identified as elements in chemistry. Further, a simple rearrangement of atoms in these materials leads to allotropes with startling contrasts in properties. Similarly, micro- and meso-scales in heterogeneous materials also dis-play this phenomenon. Human requirements propelled by necessities and wants have leveraged heterogeneity deliberately or naively. In the context of engineering materials, light weight heterogeneous materials like composites and cellular solids are outstanding inventions from the last century. The present thesis highlights this phenomenon on a meso-scale to explore generalized variants of circular and elliptical honeycomb structures (HCSs) with an emphasis on their effective transverse elastic responses, a crucial pillar of engineering design and analysis. Homogenized or effective properties are an extension of continuum hypothesis, conceived for ease in analyses. E ective properties are employed in multi-scale analyses resulting in less complex models for analysis, for example, for predicting the speed of wave propogation. The thesis extends and generalizes existing close-packed circular and elliptical HCSs to more broader configurations. Simpler periodic arrangement of the unit cells from numerous exotic possibilities directly incorporates Design for Manufacture and Assembly (DFMA) philosophy and o ers a potential scope for analysis by simpler tools resulting in handy expressions which are of great utility for designer engineers. In this regard, analytical expressions for moduli having compact forms in the case of circular HCS are developed by technical theories and rigorous theory of elasticity. Regression analysis expressions for the moduli of elliptical HCS are presented, and the elasticity solutions for the same are highlighted. The thesis consists of seven chapters with Chapter 1 presenting generalized circular and elliptical HCSs as a potential avenue beyond composite materials. Following a survey of pertinent HCS literature of these HCSs, research gaps and scope are delineated. Chapter 2 briefly y summarizes the ideas, concepts and tools including analytical and numerical methods. This chapter sets the ground for the analysis of generalized circular and elliptical HCS in the following four chapters. Following the classification of the circular HCSs, Chapter 3 assesses the complete transverse elastic responses of generalized circular HCS through technical theories which are a first-order approximation. Here, thin ring theory and the more elaborate curved beam theory are employed as models to assess the moduli. Normal moduli - E and - are obtained by employing Castigliano method, while shear moduli (G ) are obtained by solving the differential equations derived in terms of displacements. Compact expressions for moduli presented wherever possible furnish the designer with a range of moduli for different configurations and modular ratios (Ey=Ex). The results show the range of applicability of technical theories within 5% of FEA. For hexagonal arrays, these results are more refined than those in literature; while the same are new for other configurations. Surprisingly, the more elaborate curved beam theory offers no better results than the thin ring theory. Chapter 4 extends the aforementioned task of assessing the complete trans-verse elastic moduli of generalized circular HCS by employing rigorous theory of elasticity (TOE) which is a second-order approximation. Utilizing Airy stress function in polar coordinates, the boundary value problems resulting from modeling of the circular HCS under different loads are solved analytically in conjunction with FEA employing contact elements. Contact elements circumvent the point loads which give finite values of displacements in technical theories and singular values in TOE. A widely used idea of employing distributed load, statically equivalent to point load, is invoked to empower TOE. The distributed load is assumed a priori and the contact length is obtained from FEA employing con-tact elements. Thus, FEA compliments the present analytical methods. Results demonstrate a very good match between analytical method in conjunction with FEA and numerical results from FEA; the error is within 5% for very thick ring (thickness-radius ratio 0.5). Further, computationally and numerically efficient expressions for displacements give better results with same computational facility. To illustrate the effect of coating on effective moduli, a limited study based on thin ring theory and elasticity theories is undertaken in Chapter 4. The study explores the effects of moduli and thickness ratios of substrate to coating on the effective normal moduli. Employing thin ring theory with only flexure as the bending mode, we get compact expressions giving good match for very thin rings in all confifigurations. The elasticity approach presented for square array demonstrates a very good match with FEA for thick rings. Coatings offer a strategy to increase the effective moduli with same dimensions. Chapter 5 broadens the scope of circular HCS by considering elliptical HCSs. While generalized circular HCS can cater to anisotropic requirement to an extent, larger spectrum is offered by considering elliptical honeycomb structures. In this regard, a generalized version of concentric thin coated elliptical HCS is investigated for transverse moduli. Thin HCSs are explored by technical theories as in circular HCS. However, a lack of exact compact-form expressions necessitates the use of regression analysis. The resulting expressions are presented in terms of ellipticity ratio describing the ovality of the ellipse and geometric parameters. Normal moduli are obtained by Castigliano method implemented in MATHE-MATICA, but shear moduli are obtained from FEA employing beam elements. The need for FEA employing beam elements stems from the subtle fact that Castigliano method implicitly assumes preclusion of rigid body motions, while shear loading for shear moduli evaluation entails rigid body motions. Interestingly, curved beam theory, as in circular HCS, offers no better refinement in assessing the moduli as compared to thin ring theory. The graphs showing the moduli with respect to thickness and modular ratios are presented as design maps to aid the designer. Chapter 6 extends the works of thin concentric coated elliptical to thicker concentric and a novel confocal elliptical HCS, a variant of elliptical HCS. In this regard, thick concentric and confocal elliptical HCS by elasticity approach are attempted for a simple case. Airy stress function in polar coordinates is tried for concentric elliptical HCS. Confocal HCS analysis employs stress function in terms of elliptical coordinate system. After proving the correctness of the stress function for both the cases by comparing the reconstructed boundary conditions with actual boundary conditions, the restrictions in solving the case of rings under load over a small region is highlighted. A parametric study for moduli is under-taken by employing FEA. These are presented as design graphs which compare and contrast the two variants of elliptical HCS on the same graphs. The modular ratio (Ey=Ex) is conspicuously more for confocal elliptical HCS than concentric elliptical HCS. Chapter 7 gives the conclusions in a nutshell, and explores the feasibility of stress evaluation of heterogeneous media on the lines of effective media theory.