E-beam lithography and dry processing for submicron fabrication

Imperial Users onl

Implementation of the Trigonometric LMS Algorithm using Original Cordic Rotation

The LMS algorithm is one of the most successful adaptive filtering algorithms. It uses the instantaneous value of the square of the error signal as an estimate of the mean-square error (MSE). The LMS algorithm changes (adapts) the filter tap weights so that the error signal is minimized in the mean square sense. In Trigonometric LMS (TLMS) and Hyperbolic LMS (HLMS), two new versions of LMS algorithms, same formulations are performed as in the LMS algorithm with the exception that filter tap weights are now expressed using trigonometric and hyperbolic formulations, in cases for TLMS and HLMS respectively. Hence appears the CORDIC algorithm as it can efficiently perform trigonometric, hyperbolic, linear and logarithmic functions. While hardware-efficient algorithms often exist, the dominance of the software systems has kept those algorithms out of the spotlight. Among these hardware- efficient algorithms, CORDIC is an iterative solution for trigonometric and other transcendental functions. Former researches worked on CORDIC algorithm to observe the convergence behavior of Trigonometric LMS (TLMS) algorithm and obtained a satisfactory result in the context of convergence performance of TLMS algorithm. But revious researches directly used the CORDIC block output in their simulation ignoring the internal step-by-step rotations of the CORDIC processor. This gives rise to a need for verification of the convergence performance of the TLMS algorithm to investigate if it actually performs satisfactorily if implemented with step-by-step CORDIC rotation. This research work has done this job. It focuses on the internal operations of the CORDIC hardware, implements the Trigonometric LMS (TLMS) and Hyperbolic LMS (HLMS) algorithms using actual CORDIC rotations. The obtained simulation results are highly satisfactory and also it shows that convergence behavior of HLMS is much better than TLMS.Comment: 12 pages, 5 figures, 1 table. Published in IJCNC; http://airccse.org/journal/cnc/0710ijcnc08.pdf, http://airccse.org/journal/ijc2010.htm

Characterization of molybdenum black coatings with reference to photothermal conversion of solar energy

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.A study of thermal, structural, electrical and optical characteristics of molybdenum black surface coatings on various substrates has been made. The suitability of these coatings for use as selective absorbers for solar collector applications has been assessed. Molybdenum black (Mo black) coatings were prepared by electrodeposition (on aluminium) and a chemcial conversion method (on zinc and electroplated cobalt on nickel plated copper substrates). The solar absorptancer (αs) and thermal emittances (εth) of the coatings were determined from room temperature spectral reflectance measurements in the solar (0.3 to 2.5μm) and infrared regions (2.5 to 50 μm) respectively. The effect of different preparation parameters and substrate pretreatments on the spectral selectivity has been investigated in order to optimize the thermal performance. The spectral selectivity is related to the Mo-black coating thickness and surface roughness together with the microstructure, of the substrate and the intermediate layer. Dip coatings on polished zinc have significant selectivity (αs/ εth = 8.4 when αs = 0.76). The absorptance of the dip coatings is increased to 0.87 with εth = 0.13 by chemical etching of zinc prior to coating deposition. For coatings on electroplated cobalt on nickel plated copper (cobalt (NC) substrate), an absorptance as high as 0.94 has been obtained with an emittance value 0.3. By using an addition agent in the plating solution of cobalt the high emittance can be reduced to 0.1 with αs = 0.91 giving a coating with a relatively high efficiency (82.5%) for photo-thermal energy conversion. A study of the surface composition and microstructure of the coatings has been made using scanning and transmission electron microscopy together with electron diffraction, X-ray diffraction and X-ray photoelectron spectroscopy. The structural investigations indicate that Mo-black coatings contain polycrystals of orthorhombic Mo4O11 with a small proportion of Ni(OH)2. Presence of water and also Mo4O11 in the coatings are evident from IR spectroscopy study. The bandgap of the coating has been determined from optical transmission spectra (1.66 eV) and also from reflectance spectra (0.85 eV). The discrepancy between these two values has been discussed. The refractive indices of the coatings have also been estimated. The band gaps and refractive indices are found to be related to the spectral selectivity of the coatings. The durability test of the coatings shows that the coatings on etched zinc are more resistant to heat treatment than the coatings on unetched zinc. The coatings on cobalt (NC) substrates also show good stability for relatively short periods at temperatures ~400ºC. A study of the electrical properties of Mo-black coatings suggests that at electrical field strengths (greater than 106v/m the dominant conduction process is of the Poole-Frenkel type. The activation energy of the conduction process has been estimated to be -0.56 eV at higher temperatures. The effect of heat treatment on the electrical properties of the coatings has been examined. The dielectric constant of Mo-black has been estimated from A. C. measurements. At high frequency (20 kHz) the value of the dielectric constant is about 4.0.Association of Commonwealth Universities; Department of Mechanical Engineering, Brunel Universit

GWAS Meta-Analysis: Methodology and Application to Human Meiotic Recombination

Human meiotic recombination is critical to successful human reproduction and to maintain genetic diversity. Recombination anomalies are associated with aberrant meiotic outcomes with significant consequences. One important method for studying recombination is genome-wide association studies (GWAS) of recombination phenotypes. Because such studies require nuclear or three-generation family samples that have been genotyped on GWAS chips, the number of suitable datasets is limited. The goal of this dissertation is to develop methods for increasing the available sample sizes for GWAS of recombination phenotypes. We developed two different approaches for increasing sample size. First, we made it possible to include additional family types in the analysis. We developed methods for scoring recombination for half-sibling pedigrees and three generation pedigrees with ungenotyped individuals. Second, we developed a regionally smoothed meta-analysis method for GWAS data, which will allow the combination datasets that have been genotyped on different chips. This method will help increase available sample sizes for recombination studies, but is also applicable to all GWAS studies. The public health significance of this work is that our developments will allow us to find new genes that control recombination and more information about already-known genes. This information can be used for improved treatment and prevention of the consequences of aberrant recombination, including infertility and births with significant chromosomal anomalies

Methionine and Glycine Stabilize Mitochondrial Activity in Sake Yeast During Ethanol Fermentation

Dodatak aminokiselina u fermentacijsku podlogu utječe na rast i aktivnost kvasca, a zadržavanje aktivnosti mitohondrija tijekom alkoholnog vrenja je kritično za aktivnost pivskog kvasca. Međutim, mehanizam djelovanja aminokiselina u fermentacijskoj podlozi i njihov utjecaj na aktivnost mitohondrija pivskog kvasca tijekom vrenja još uvijek nije poznat. U ovom radu smo utvrdili da aminokiseline u fermentacijskoj podlozi, osobito metionin i glicin, stabiliziraju aktivnost mitohondrija kvasca tijekom proizvodnje pića sake. Pomoću mutanta atg32△, koji ima narušenu aktivnost mitohondrija, istražili smo aminokiseline koje povećavaju aktivnost mitohondrija kvasca tijekom vrenja. Identificirali smo metionin i glicin kao aminokiseline koje bi mogle povećati aktivnost mitohondrija kvasca tijekom proizvodnje pića sake. Da bismo to potvrdili, izmjerili smo količinu reaktivnih oblika kisika u kvascu nakon vrenja u podlozi s metioninom i glicinom. Kvasac koji je fermentirao u podlozi s metioninom i glicinom zadržao je relativno veliku količinu reaktivnih oblika kisika u usporedbi s kvascem koji je fermentirao u podlozi bez dodatka aminokiselina. Osim toga, stanice koje su fermentirale u podlozi s dodatkom metionina imale su različit metabolom od stanica koje su fermentirale u podlozi bez dodatka aminokiseline. Rezultati pokazuju da određene aminokiseline, poput metionina i glicina, stabiliziraju aktivnost mitohondrija kvasca tijekom proizvodnje pića sake i na taj način upravljaju aktivnošću kvasca.Addition of amino acids to fermentation media affects the growth and brewing profiles of yeast. In addition, retaining mitochondrial activity during fermentation is critical for the fermentation profiles of brewer’s yeasts. However, a concrete mechanism linking amino acids in fermentation media with mitochondrial activity during fermentation of brewer’s yeasts is yet unknown. Here, we report that amino acids in fermentation media, especially methionine (Met) and glycine (Gly), stabilize mitochondrial activity during fermentation of sake yeast. By utilizing atg32Δ mutant sake yeast, which shows deteriorated mitochondrial activity, we screened candidate amino acids that strengthened the mitochondrial activity of sake yeast during fermentation. We identified Met and Gly as candidate amino acids that fortify mitochondrial activity in sake yeast during fermentation. To confirm this biochemically, we measured reactive oxygen species (ROS) levels in sake yeast fermented with Met and Gly. Yeast cells supplemented with Met and Gly retained high ROS levels relative to the non-supplemented sake yeast. Moreover, Met-supplemented cells showed a metabolome distinct from that of non-supplemented cells. These results indicate that specific amino acids such as Met and Gly stabilize the mitochondrial activity of sake yeast during fermentation and thus manipulate brewing profiles of yeast

Joint workload scheduling and BBU allocation in cloud-RAN for 5G networks

Copyright 2017 ACM. Cloud-radio access network (C-RAN) emerges as a solution to satisfy the demand for a diverse range of applications, massive connectivity, and network heterogeneity. C-RAN uses central cloud network for processing user requests. Efficient management of cloud resources (e.g., computation and transmission resources) is one of the important challenges in C-RAN. In this paper, we investigate a joint workload scheduling and baseband unit (BBU) allocation in Cloud-RAN for 5G networks. First, we establish a queueing model in C-RAN. We then formulate an optimization problem for joint workload scheduling and BBU allocation with the aim to minimize mean response time and aggregate power. Queueing stability and workload conservation constraints are considered in the optimization problem. To solve this problem, we propose an energy efficient joint workload scheduling and BBU allocation (EE-JWSBA) algorithm using the concept of queueing theory. The EE-JWSBA algorithm is evaluated via simulations by considering three different scheduling weights (e.g., random, normalized, and upper limit). Simulation results demonstrate the effectiveness of proposed scheme using different scheduling weights

Isotopic Evaluation on Nitrogen Reduction in Mangrove Ecosystems of Okinawa, Japan

2020東京農業大

The Melanoma Skin Cancer Detection Using Convolutional Neural Network

The most common cause of death for persons in the modern world is melanoma skin cancer. Melanoma is an aggressive kind of skin cancer that typically develops on parts of the body exposed to sunlight, UV radiation, dust, pollution, and microbes. A study found that 79% of humans who do have melanoma skin cancer in its early stages are unaware of having it. When it is finally identified, it may have progressed further into the skin and may have impacted other parts of the body, making treatment extremely difficult and it also makes the survival rate for humans very low. As a result, melanoma skin cancer kills the majority of its victims. If melanoma is identified or recognized in the early stages, then it could have been cured easily and it also has a bigger survival rate for humans. There is an automated system that has been designed with the compilation of data sets with a variety of diagnoses. This automated system will help to detect in early stages of melanoma. Convolutional neural network technology was initially employed in our automated system to classify data. But as a result, our accuracy was poor. Then, we used support vector machines (SVMs) to analyze the entire dataset after categorizing and segmenting the data into zones, using Tensor Flow libraries to implement the entire model. After using the model, we achieve a 96% accuracy rate

Probiotic Characteristics of Pediococcus pentosaceus and Apilactobacillus kunkeei Strains: The lactic Acid Bacteria Isolated from Bangladeshi Natural Honey

Background and Objective: Lactic acid bacteria are known for their strong probiotic effects on the hosts. The probiotic characterization of lactic acid bacteria from Bangladeshi natural honey is limited. The objectives of this study included isolation and assessment of the probiotic and safety characteristics of lactic acid bacteria in Bangladeshi honey. Materials and Methods: Spread and streak plate techniques were used for the bacterial isolation and purification. Isolates were identified using 16S rRNA gene sequence analysis. Agar well diffusion and poisoned food methods were used for antibacterial and antifungal assessments, respectively. Antioxidant activity was carried out based on the microbial free-radical scavenging ability. Microbial autoaggregation, coaggregation and adhesion were assessed using cell sedimentation assay. Blood-agar was used in the hemolytic assay. Antibiotic susceptibility assay was carried out using disc diffusion method. Results and Conclusion: From a total of 25 strains isolated from honey, ten Gram-positive, catalase-negative non-spore-forming isolates were selected and used in agar well diffusion assay. Three of the isolates showed prominent antimicrobial effects with large inhibition zones against all the pathogenic strains, including Bacillus cereus, Staphylococcus aureus, Vibrio cholerae, Salmonella typhi and Candida albicans. Extensive characterization of these isolates was carried out, which revealed their growth and biochemical characteristics and carbohydrate fermentation abilities. Moreover, 16S rRNA gene sequence analysis suggested that the isolates belonged to Pediococcus pentosaceus (two strains) and Apilactobacillus kunkeei. Their tolerance to simulated gastric conditions was assessed in vitro wherein the isolates showed significant survival in low pH, bile salts and phenol. They showed good adhesion ability to ethyl acetate, chloroform and xylene as well as high autoaggregation and coaggregation characteristics. Moreover, free-radical scavenging activity of the isolates suggested the presence of considerable antioxidant effects. In safety assessment, the isolates did not show hemolytic activities and were resistant to several antibiotics. Therefore, these results indicate that honey can be an important source of beneficial lactic acid bacteria species providing several probiotic advantages. Conflict of interest: The authors declare no conflict of interes

Corporate Social Activities of Private Commercial Banks in Bangladesh: An Evaluation

Every business organization has some responsibilities to the people because organizations need people to sell their products. No organization can make profit without selling products to the customers. However, every bank needs customers to sell products for earning profits. In this case, the authority of each bank should accomplish some activities for the well-being of the people in the society. Thus, this paper attempts to evaluate the corporate social activities of private commercial banks in Bangladesh. This paper also tries to explore the problems of corporate social activities accomplished by the private commercial banks in Bangladesh and suggests some measures to enhance the performance of the banks while they are accomplishing social activities for the people in the society