Pitch Angle Control for a Small-Scale Darrieus Vertical Axis Wind Turbine with Straight Blades (H-type VAWT)

Unlike the horizontal axis wind turbines, only a few studies have been conducted recently to improve the performance of a Darrieus Vertical Axis Wind Turbine with straight blades (H-type VAWT). Pitch angle control technique is used to enhance the performance of an H-type VAWT in terms of power output and self-starting capability. This thesis aims to investigate the performance of an H-type VAWT using an intelligent blade pitch control system. Computational Fluid Dynamics (CFD) is used to determine the optimum pitch angles and study their effects on the aerodynamic performance of a 2D H-type VAWT at different Tip Speed Ratios (TSRs) by calculating the power coefficient (Cp). The results obtained from the CFD model are used to construct the aerodynamic model of an H-type VAWT rotor, which is required to design an intelligent pitch angle controller based on Multi-Layer Perceptron Artificial Neural Networks (MLP-ANN) method. The performance of the blade pitch controller is investigated by adding a conventional controller (PID) to the MLP-ANN controller (i.e., Hybrid controller). For stability analysis, an H-type VAWT is modeled in nonlinear state space by determining the mathematical models for an H-type VAWT components along with Hybrid control scheme. The effectiveness of proposed pitch control system and the CFD results are validated by building an H-type VAWT prototype. This prototype is tested outdoor extensively at different wind conditions for both fixed and variable pitch angle configurations. Results demonstrate that the blade pitching technique enhanced the performance of an H-type VAWT in terms of power output by around 22%

The effects of nano-composites in bulk heterojunction thin-film organic solar cells.

Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.Abstract available in PDF

The Mediating Role of Value Co-creation on the Relationship between Structural supply Chain Orientation and Marketing Adaptiveness: A Structural Equitation Model

the success of the supply chain depends upon the ability to adjust theinterests of various stakeholders of the supply chain members, which is has become a necessity to maintain a competitive advantage in a dynamic environment. SCO affects not only the single firm performance within the supply chain but also the overall performance of the supply chain.Drawing on RBV this study seek to investigate the mediating effect of value co-creation on the relationship between Structural Supply chain orientation and marketing adaptiveness of industrial firms in sudan. the study collected a data from non probability sample of 180 manufacturing firms, This study applies structural equation modelling (SEM) method for data analysis using The result indicates. That both Cooperative Norms and value co-creation significantly contribute to the marketing adaptiveness , also credibility have significance effect on value co-creation . The finding also suggests that value co-creation partially mediates the relationship between structural supply chain orientation(credibility) and marketing adaptiveness. Moreover industrial firms can more adaptability in marketing by maintaining and developing cooperative norms and participating partners in the process of creating value Key Words: Supply chain orientation, Structural SCO, Value co-creation, marketing adaptivenes

Enhancement of glutamine synthetase activity in Paenibacillus polymyxa by optimization of different growth conditions

Biological nitrogen fixation is highly regulated at the transcriptional level by sophisticated regulatory networks that respond to multiple environmental signals. Glutamine synthetase (GS) occupies a central position in cellular metabolism and offer to the cell, a potential point for regulation of biosynthetic function. The aim of this work is to enhance the activity of GS in Paenibacillus polymyxa through altering the constituents of the growth medium, thereby increasing the nitrogen fixation capability. Two bacterial strains were identified as P. polymyxa by 16S rRNA gene (Accession No AB727983). High GS activity was recorded in the two strains, in presence of the divalent cations Mg+2 and Mn+2. Western blot analysis confirmed the presence of the GS at approximately ~60 kDa. GS activity was found to be affected by growth medium, carbon source, nitrogen source and sodium chloride. LB supplemented with 7% glycerol, 0.4% asparagine and 0.15% sodium chloride gave the highest GS activity.Key words: Glutamine, Paenipacillus polymyxa, 16S rRNA, nitrogen fixation, western blot, Mg+2 and Mn+2

A new low molecular mass alkaline cyclodextrin glucanotransferase from Amphibacillus sp. NRC-WN isolated from an Egyptian soda lake

Background: Cyclodextrin glucanotransferase (CGTase) is one of the most industrially important enzymes used in the commercial production of cyclodextrins (CDs). Alkaliphilic bacteria have attracted much interest in the last few decades because of their ability to produce extracellular enzymes that are active and stable at high pH values. Here, we report the isolation of a new CGTase from alkaliphilic bacteria collected from Egyptian soda lakes and describe the purification and biochemical characterization of this CGTase. Results: Screening for CGTase-producing alkaliphilic bacteria from sediment and water samples collected from Egyptian soda lakes located in the Wadi Natrun valley resulted in the isolation of a potent CGTase-producing alkaliphilic bacterial strain, designated NRC-WN. Strain NRC-WN was belonging to genus Amplibacullus by 16S rDNA sequence analysis (similarity: ca. 98%). Among the tested nitrogen and carbon sources, peptone (0.15%, w/v) and soluble starch (0.4%, w/v) allowed maximal CGTase production by Amphibacillus sp. NRC-WN. CGTase was successfully purified from Amphibacillus sp. NRC-WN up to 159.7-fold through a combination of starch adsorption and anion exchange chromatography, resulting in a yield of 84.7%. SDS-PAGE analysis indicated that the enzyme was purified to homogeneity and revealed an estimated molecular mass of 36 kDa, which makes it one of the smallest CGTases reported in the literature. The purified enzyme exhibited maximum activity at 50oC and was stable up to 70oC, retaining 93% of its initial activity after treatment for 1 hr. Furthermore, Ca2+ ions (10 mM) significantly enhanced the thermal stability of the CGTase. The purified enzyme was active and stable over a wide pH range, showing maximal activity at pH 9.5. The enzyme was significantly stimulated by Zn2+, Ca2+ and Co2+ but was completely inhibited in the presence of Fe3+ and mercaptoethanol. The Km and Vmax values of the purified CGTase were estimated to be 0.0434 mg/ml and 3,333.3 mg \u3b2-CD/ml/min, respectively. \u3b2-CD was the predominant product of starch degradation by the Amphibacillus sp. NRC-WN CGTase, followed by \u3b1-and \u3b3-CDs. Conclusions: A new low molecular mass alkaline CGTase was purified from a newly identified alkaliphilic Amphibacillus sp. NRC-WN isolate from the Egyptian soda lakes. The enzyme showed promising thermal and pH stability and a high affinity toward starch as a natural substrate

Factors affecting compliance with the measles vaccination schedule in a Brazilian city

CONTEXT AND OBJECTIVE: The success of vaccination campaigns depends on the degree of adherence to immunization initiatives and schedules. Risk factors associated with children's failure to receive the measles vaccine at the correct age were studied in the city of São Paulo, Brazil. DESIGN AND SETTING: Case-control and exploratory study, in the metropolitan area of São Paulo. METHODS: The caregivers of 122 children were interviewed regarding their perceptions and understanding about the measles vaccination and the disease. RESULTS: The results showed that age, region of residence, marital status and education level were unrelated to taking measles vaccines adequately. Most individuals remembered being informed about the last annual vaccination campaign by television, but no communication channel was significantly associated with vaccination status. The answers to questions about knowledge of the disease or the vaccine, when analyzed alone, were not associated with taking measles vaccinations at the time indicated by health agencies. The results showed that, when parents felt sorry for their children who were going to receive shots, they delayed the vaccination. Most of the children did not take the measles vaccination on the exactly recommended date, but delayed or anticipated the shots. CONCLUSION: It is clear that there is no compliance with the government's recommended measles vaccination schedule (i.e. first dose at nine and second at 15 months of age, as recommended in 1999 and 2000). Feeling sorry for the children receiving shots can delay vaccination taking

PRECODER DESIGN BASED ON INTER-ANTENNA LEAKAGE MINIMIZATION FOR MU-MIMO

Multiple Input Multiple Output (MIMO) is an important technological development that makes use of the spatial dimension hitherto underutilized to increase the channel capacity. MIMO today is an integral part of many up to date wireless standards, such as: IEEE 802.lln for wireless LAN, WiMAX 2, and even the latest ITU-T mobile communication/ L TE-Advanced standard adopted by 3GPP in 20 II. The performance of the Multi-user MIMO (MU- MIMO) broadcast channel highly depends on the precoding scheme used for each user at the transmission front end. The MU-MIMO precoding design process is broadly classified in either of the following two frameworks, namely linear and nonlinear. Given the practical implementation challenges of the nonlinear precoding methods, preference is given to linear methods resulting in simple but high performance and efficient transmission methods. In this thesis, a new MU-MIMO precoding method is developed based on optimizing what is termed as Per-Antenna Signal to Leakage plus Noise Ratio (PA�SLNR). The optimization is facilitated using Fukunaga-Koontz Transform (FKT) that not only overcomes the problem of singularity but also helps reduce computation. Furthermore, we investigate the proposed method on a typical and practical wideband channel where OFDM is used to convert the wideband frequency selective channel into a set of narrow band flat sub-channels. The performance of the proposed method is validated against other methods available in the literature. finally, we extend the use of our proposed method to the extremely important and practical deployment scenario of cellular communication where MU-MIMO precoding is devised for the inter-cell interference cancelation by utilizing, what is known as, Multi-Cell Processing (MCP). We demonstrate the importance of precoding in cellular scenario by the capacity enhancement of both the cell edge users and the overall cellular system