A nanofluid is the suspension of nanoparticles in a base fluid. Nanofluids are promising for heat transfer enhancement due to their high thermal conductivity. Presently, discrepancy exists in nanofluid thermal conductivity data in the literature, and enhancement mechanisms have not been fully understood yet. In the first part of this study, a literature review of nanofluid thermal conductivity is performed. Experimental studies are discussed through the effects of some parameters such as particle volume fraction, particle size, and temperature on conductivity. Enhancement mechanisms of conductivity are summarized, theoretical models are explained, model predictions are compared with experimental data, and discrepancies are indicated. Nanofluid forced convection research is important for practical application of nanofluids. Recent experiments showed that nanofluid heat transfer enhancement exceeds the associated thermal conductivity enhancement, which might be explained by thermal dispersion, which occurs due to random motion of nanoparticles. In the second part of the study, to examine the validity of a thermal dispersion model, hydrodynamically developed, thermally developing laminar Al2O3/water nanofluid flow inside a circular tube under constant wall temperature and heat flux boundary conditions is analyzed by using finite difference method with Alternating Direction Implicit Scheme. Numerical results are compared with experimental and numerical data in the literature and good agreement is observed especially with experimental data, which indicates the validity of the thermal dispersion model for explaining nanofluid heat transfer. Additionally, a theoretical analysis is performed, which shows that usage of classical correlations for heat transfer analysis of nanofluids is not valid.

Determination of thallium is important due to its toxic effects on the environment and human health. Extremely low abundance of thallium in earth crust requires very sensitive and accurate methods for determination of this element. Although volatile compound generation is a sensitive, fast and economical method, thallium determination by this method has not been sufficiently investigated in literature, because of the fact that the formation of volatile forms of this element is a difficult task. A continuous flow volatile compound generation system was developed and parameters that affect the analytical signal were optimized. Sample solutions were acidified with 0.5 mol/L HNO3 and prepared in 0.0005% (v/v) rhodamine B and 1.0 mg/L Pd while 0.5% (m/v) NaBH4 stabilized in 0.5% (m/v) NaOH was used as reductant. Fast decomposition and unstability of thallium volatile species affected system performance negatively. Flow injection volatile compound generation studies were carried out with a special system. After optimizations, LOD and LOQ values were calculated as 12 ng/mL and 40 ng/mL according to peak height values in HNO3 medium. Similarly, in HCl medium LOD and LOQ values were calculated as 14 ng/mL and 45 ng/mL. Addition of Te and Pd to the sample solution containing co-enhancement reagent rhodamine B improved volatile compound generation efficiency in peak height by 3.6 and 9.3, respectively. Type of the acid used was affected peak heights and peak shapes of Tl+ and Tl3+ volatile species and HNO3 medium gave better results. By changing the location of introduction for Ar gas, the sources of memory effects and reasons of peak broadening were investigated. Most of the memory effects were coming from the gas-liquid separator (GLS) or before the GLS, as well as T-tube atomizer. Nature and behavior of Tl volatile species were also investigated and it was found that Tl and also Pd were generated in the form of nanoparticles. Transmission electron microscopic (TEM) measurements prove the presence of Tl nanoparticles in the analyte species transported to the atomizer by the effect of carrier Ar gas.

Today, infrared cameras are used especially for target tracking and surveillance operations. However, they have a high dynamic range output, and the standard display devices cannot handle them. In order to show them on common devices, the dynamic range is cropped. Thus, the contrast of the image is reduced. This is called as the High Dynamic Range (HDR) Compression. Although several algorithms have been proposed for preserving details during the HDR compression process, it cannot be used to enhance the local contrasts of image contents. In this thesis, we compare the performances of contrast enhancement techniques, which are suitable for real time applications. The methods experimented are generally histogram based methods. Some modifications are also proposed in order to reduce computational complexity of the process. Performances of these methods are compared with common objective quality metrics on different image sets.

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The bandwidth-enhancement characteristics of slot-loaded rectangular microstrip antennas constructed on a thin microwave substrate have been investigated in this dissertation. The primary design process about this topic is demonstrated. Firstly, a new antenna design idea is provided from pre-determined antenna design specifications or obtained antenna performances from the previous antenna design, which lead to a novel antenna configuration. From the results of the simulation software IE3DTM, the characteristics of this new antenna configuration are obtained and compared with the experimental results. The antenna configuration is also modified to achieve a final optimal design from the comparison results. The study of the single-feed dual-frequency rectangular microstrip antenna with a pair of bent slots is first presented. By embedding properly-designed slots on a rectangular microstrip patch, the impedance characteristics of this antenna design have been effectively changed to exhibit dual-resonant behavior, which result in the excitation of two adjacent resonant modes with similar radiation characteristics. Furthermore, the two resonant modes can be excited at frequencies very close to each other to form a wider operating bandwidth by embedding additional perturbation slots. Four successful antenna designs with different embedded-slot shapes for bandwidth enhancement have been implemented and discussed in this dissertation.

To achieve two main objectives, viz., to increase the system capacity and having higher data rates, of 3G system for individual users, it comes up to be the unprecedented demand on both communication bandwidth and powerful DSP processing techniques. In this thesis, a new space-time encoding scheme, referred to as the Virtual Constellation Mapping (VCM) scheme associated with the turbo encoder, is devised to enhance transmission data rate and spectral efficiency. It also alleviates the requirement of powerful signal processing technique. In fact, the proposed scheme is very simple and could be used to achieve full utilizing encoding efficiency. It means that the new scheme is easy in practical implementation. To verify the advantages of this new scheme, we apply it to both the 3GPP FDD of WCDMA system and OFDM based Wireless LAN system. First, by comparing the proposed scheme with the conventional standards 3GPP scheme, the information data rate is increased from 384 kbps information data rate to 450.4 kbps, that is 17 % improvement. It should be noted by using the new approach, other system components of 3GPP, e.g., modulation scheme, control bits and the data rate of the QPSK modulators outputs, are all the same. Moreover, this VCM scheme can be applied to the multicarrier modulation or the Wireless LAN with the OFDM modulation. Computer simulation results showed that with the same transmission data rate, our scheme is more robustness compare with the conventional space-time trellis coded OFDM scheme, in high Doppler fading channel. In addition, the proposed scheme required less decoding complexity as the standards, when it is implemented in the 3GPP system and the OFDM system with space-time trellis coding scheme.

Large digital libraries typically contain large collections of heterogeneous resources intended to be delivered to a variety of user communities. One key challenge for these libraries is providing tight integration between resources both within a single collection and across the several collections of the library with out requiring hand coding. One key tool in doing this is elucidating the internal structure of the digital resources and using that structure to form connections between the resources. The heterogeneous nature of the collections and the diversity of the needs in the user communities complicates this task. Accordingly, in this thesis, I describe an approach to implementing a feature identification system to support digital collections that provides a general framework for applications while allowing decisions about the details of document representation and features identification to be deferred to domain specific implementations of that framework. These deferred decisions include details of the semantics and syntax of markup, the types of metadata to be attached to documents, the types of features to be identified, the feature identification algorithms to be applied, and which features should be indexed. This approach results in strong support for the general aspects of developing a feature identification system allowing future work to focus on the details of applying that system to the specific needs of individual collections and user communities.

In this paper, we searched the parameter of BEF (Brightness enhancement film) using commercial FRED server for backlight module. The pattern analysis was carried out to understand its characteristic. The current structures used in LCD backlight are double-layer BEF. In addition, BEF of 3M takes the lion¡¦s share. But this may increase the thickness and cost of backlight module. In order to avoid those disadvantages, we tried to design single-layer BEF and characterize the effect through parameters study by using FRED software simulation. pyramid-shaped microlens array of BEF was constructed. Therefore, the effect of the variation of the structure parameters can be analyzed, such as prismatic degree (£c), prismatic structure on the brightness enhancement. It can be found from the result of simulation that the changes of the prismatic degree (£c) of 85 degree influence the brightness enhancement the most.

Hearing impairment is the number one chronic disability affecting people in the world. Many people have great difficulty in understanding speech with background noise. This is especially true for a large number of elderly people and the sensorineural impaired persons. Several investigations on speech intelligibility have demonstrated that subjects with sensorineural loss may need a 5-15 dB higher signal-to-noise ratio than the normal hearing subjects. While most defects in transmission chain up to cochlea can nowadays be successfully rehabilitated by means of surgery, the great majority of the remaining inoperable cases are sensorineural hearing impaired, Recent statistics of the hearing impaired patients applying for a hearing aid reveal that 20% of the cases are due to conductive losses, more than 50% are due to sensorineural losses, and the rest 30% of the cases are of mixed origin. Presenting speech to the hearing impaired in an intelligible form remains a major challenge in hearing-aid research today. Even-though various methods have been suggested in the literature for the minimization of noise from the contaminated speech signals, they fail to give good SNR improvement and intelligibility improvement for moderate to-severe sensorineural loss subjects. So far, the power and capability of Newton's method, Nonlinear adaptive filtering methods and the feedback type artificial neural networks have not been exploited for this purpose. Hence we resort to the application of all these methods for improving SNR and intelligibility for the sensorineural loss subjects. Digital hearing aids frequently employ the concept of filter banks. One of the major drawbacks of this techniques is the complexity of computation requiring more number of multiplications. This increases the power consumption. Therefore this Thesis presents the new approach to speech enhancement for the hearing impaired and also the construction of filter bank in Digital hearing aid with minimum number of multiplications. The following are covered in this thesis. One of the most important application of adaptive systems is in noise cancellation using adaptive filters. The ANC setup requires two input signals (viz., primary and reference). The primary input consists of the sum of the desired signal and noise which is uncorrelated. The reference input consists of mother noise which is correlated in Some unknown way with noise of primary input. The primary signal is obtained by placing the omnidirectional microphone just above one ear on the head of the KEMAR mannikan and the reference signal is obtained by placing the hypercardioid microphone at the center of the vertebral column on the back. Conventional speech enhancement techniques use linear schemes for enhancing speech signals. So far Nonlinear adaptive filtering techniques are not used in hearing aid applications. The motivation behind the use of nonlinear model is that it gives better noise suppression as compared to linear model. This is because the medium through which signals reach the microphone may be highly nonlinear. Hence the use of linear schemes, though motivated by computational simplicity and mathematical tractability, may be suboptimal. Hence, we propose the use of nonlinear models to enhance the speech signals for the hearing impaired: We propose both Linear LMS and Nonlinear second order Volterra LMS schemes to enhance speech signals. Studies conducted for different environmental noise including babble, cafeteria and low frequency noise show that the second-order Volterra LMS performs better compared to linear LMS algorithm. We use measures such as signal-to-noise ratio (SNR), time plots, and intelligibility tests for performance comparison. We also propose an ANC scheme which uses Newton's method to enhance speech signals. The main problem associated with LMS based ANC is that their convergence is slow and hence their performance becomes poor for hearing aid applications. The reason for choosing Newton's method is that they have high performance adaptive-filtering methods that often converge and track faster than LMS method. We propose two models to enhance speech signals: one is conventional linear model and the other is a nonlinear model using a second order Volterra function. Development of Newton's type algorithm for linear mdel results in familiar Recursive least square (RLS) algorithm. The performance of both linear and non-linear Newton's algorithm is evaluated for babble, cafeteria and frequency noise. SNR, timeplots and intelligibility tests are used for performance comparison. The results show that Newton's method using Volterra nonlinearity performs better than RLS method. ln addition to the ANC based schemes, we also develop speech enhancement for the hearing impaired by using the feedback type neural network (FBNN). The main reason is that here we have parallel algorithm which can be implemented directly in hardware. We translate the speech enhancement problem into a neural network (NN) framework by forming an appropriate energy function. We propose both linear and nonlinear FBNN for enhancing the speech signals. Simulated studies on different environmental noise reveal that the FBNN using the Volterra nonlinearity is superior to linear FBNN in enhancing speech signals. We use SNR, time plots, and intelligibility tests for performance comparison. The design of an effective hearing aid is a challenging problem for sensorineural hearing impaired people. For persons with sensorineural losses it is necessary that the frequency response should be optimally fitted into their residual auditory area. Digital filter enhances the performance of the hearing aids which are either difficult or impossible to realize using analog techniques. The major problem in digital hearing aid is that of reducing power consumption. Multiplication is one of the most power consuming operation in digital filtering. Hence a serious effort has been made to design filter bank with minimum number of multiplications, there by minimizing the power consumption. It is achieved by using Interpolated and complementary FIR filters. This method gives significant savings in the number of arithmetic operations. The Thesis is concluded by summarizing the results of analysis, and suggesting scope for further investigation

<p>This Master Thesis has been conducted at the National Laboratory of Forensic Science (SKL) in Linköping. When images that are to be analyzed at SKL, presenting an interesting object, are of bad quality there may be a need to enhance them. If several images with the object are available, the total amount of information can be used in order to estimate one single enhanced image. A program to do this has been developed by studying methods for image registration and high resolution image estimation. Tests of important parts of the procedure have been conducted. The final results are satisfying and the key to a good high resolution image seems to be the precision of the image registration. Improvements of this part may lead to even better results. More suggestions for further improvementshave been proposed.</p> / <p>Detta examensarbete har utförts på uppdrag av Statens Kriminaltekniska Laboratorium (SKL) i Linköping. Då bilder av ett intressant objekt som ska analyseras på SKL ibland är av dålig kvalitet finns det behov av att förbättra dessa. Om ett flertal bilder på objektet finns tillgängliga kan den totala informationen fråndessa användas för att skatta en enda förbättrad bild. Ett program för att göra detta har utvecklats genom studier av metoder för bildregistrering och skapande av högupplöst bild. Tester av viktiga delar i proceduren har genomförts. De slutgiltiga resultaten är goda och nyckeln till en bra högupplöst bild verkar ligga i precisionen för bildregistreringen. Genom att förbättra denna del kan troligtvis ännu bättre resultat fås. Även andra förslag till förbättringar har lagts fram.</p>