1,721,139 research outputs found
Wind Energy System with Matrix Converter
No full textKeeping in mind the end goal to address energy issues, considering financial and natural variables, a Wind Energy Conversion System (WECS) is bit-by-bit gaining interest as the suitable source of renewable energy. In this chapter, a direct AC-AC Matrix Converter (MC) is utilized to interface an isolated static load fed from the WECS. Due to the advantage of lower cost, maintenance simplicity and short circuit self-protection, the self-excited induction generator is used to generate electric energy. The MC is used instead of the conventional rectifier-inverter converter because it does not contain the bulky size capacitor, the ability of controlling the input displacement factor and the unity factor can be achieved. Moreover, the MC can be provided in a simple construction, and gives a wide range of output frequency. In comparison with cycloconverter, the MC can give an output frequency that may be equal, less or greater than input frequency. This chapter introduces a modified algorithm for space vector modulation that reduces the total harmonic distortion of the output voltage so the size and cost of the required filter can be reduced. Moreover, a modified open loop control of matrix converter with indirect space vector modulation is introduced to provide constant frequency and output voltage even if the wind speed changed
In-The-Wild Reading Activity Evaluation Using Self-Supervision
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Electrochemical Characterization of Some Electroactive Nucleophilic Substitution Reactions
No full textThis thesis submitted in partial fulfillment of the requirements for the degree of
Master of Philosophy (M.Phil) in Chemistry.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 149-154).The substitution reaction of Catechol in presence of Imidazole, L-Arginine and L-Serine have been studied by cyclic voltammetry, controlled potential coulometry and differential pulse voltammetry techniques using Glassy carbon (GC), Gold (Au) and Platinum (Pt) electrodes. The voltammetric studies have been carried out by varying the composition of Catechol, Imidazole, L-Arginine and L-Serine in the buffer solution of different pH, different electrodes and scan rate.
Pure Imidazole, L-Arginine and L-Serine are electro-inactive whereas pure Catechol is electro-active. In the second scan of potential, a new anodic peak appears at the lower potential and the oxidation and reduction peak shifted with respect of pure catechol after addition of Imidazole, L- Arginine and L-Serine in catechol solution. At the same time the anodic and cathodic peak current decreases significantly compared with the pure catechol that indicates the participation of reaction of o-benzoquinone with Imidazole, L-Arginine and L-Serine. The reaction products generated from the reaction of catechol in presence of Imidazole, L-Arginine and L-Serine are assumed to be 4-(1H-imidazol-1-yl)cyclohexa- 3,5-diene-1,2-dione- 2-amino-4-(1-(3,4-dioxocyclo hexa-1,5-dien-1-yl)guanidino)-4- oxobutanoic acid and 3-hydroxy-2-((3-hydroxy-4-oxocyclohexa-2,5-dien-1- ylidene)amine)propanoic acid respectively that undergo electron transfer at more negative potentials than the Catechol. The electro –synthesized products generated from Catechol with Imidazole, L-Arginine and L-Serine were isolated. The formation of Catechol-nucleophile adducts are also confirmed by FTIR spectra.
The pH effect of catechol in presence of Imidazole, L-Arginine and L-Serine has been investigated in different pH from 3 to 11. From the experiment it has been observed that almost no new anodic peak appeared after repetitive cycling at pH 3-5 (acidic media) and pH 9-11 (basic media). At pH 7, the o-benzoquinone undergoes nucleophilic attack by the amines that is reflected from voltammetric new anodic peak, A0 appeared after repetitive cycling. The slopes of the peak potential, Ep vs pH plot has determined graphically as the anodic peaks of Catechol-Imidazole (60 mV/pH), Catechol-Arginine (56mV/pH) and Catechol-Serine (61.5 mV/pH) at 0.1V/s.Md. Rabiul IslamMaster of Philosophy (M.Phil) in Chemistr
Nitrate Electrochemical Sensor Comprising Silver Nanoparticles Carbon Nanotubes Composite
No full textThe cost-effectiveness, functionality, and ease of use of the nanomaterial-enabled electrochemical sensors make them ideal for routine, on-site detection of the nitrate ions (NO3-) in a variety of environmental samples. The excellent developments and adaptable characteristics of the nanomaterials have significantly increased the analytical functioning of the electrochemical nitrate (NO3-) sensors. Nitrate detection would go a long way toward aiding in the management and control of such ions and their devastating effects on air pollution. Additionally, the detection of nitrate ions (NO3-) in an aqueous solution is significantly complicated by the variable quantity and signal overlap with other ions. The objective of this research was to detect nitrate ions using glassy carbon electrodes modified with silver nanoparticles carbon nanotubes composite and outer layer: chitosan. Glassy carbon electrodes/carbon nanotubes/Silver nanoparticles/chitosan electrodes (GCE/MWCNT/AgNPs/CS) were constructed and used to detect nitrate ions. GCE/MWCNT/AgNPs/CS sensor has demonstrated a lower detection limit and higher sensitivity (~30 mA/Μ) fhe nitrate detection (NO3-) when compared with the glassy carbon electrodes alone. Under optimal experimental conditions, the fabricated sensor (GCE/MWCNT/AgNPs/CS) exhibited a LOD of ~8 μM with a correlation coefficient of 0.99 and a greater linear range of 0 – 900 μM
Processing conditions for quality improvement of parboiled rice
No full text筑波大学University of Tsukuba博士（農学）Doctor of Philosophy in Agricultural Science2001【要旨】thesi
TECHNICAL EFFICIENCY OF BORO RICE CULTIVATION IN JAMALPUR DISTRICT
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Submitted to the Faculty of Agribusiness Management,
Sher-e-Bangla Agricultural University, Dhaka,
in Partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE (MS)
IN
AGRICULTURAL ECONOMICSBangladesh is the country with distinct agricultural setting. It is the most populous
country in the world with 163.7 million populations and population density of 1103
person per square kilometer. Boro rice production plays an important role in achieving
food security of Bangladesh. Due to high population growth rate, food security has
become a burning issue in Bangladesh economy where 21.8 percent people lived under
poverty level. Efficiency of Boro rice producer is an important factor because of rice is
the staple food in Bangladesh. Annual consumption of rice is 134.02 kg. per capita in
Bangladesh. This study attempted to examine the profitability and technical efficiency
level of Boro rice farmers and inefficiency factors which affects production. One
hundred and twenty (120) Boro rice farmers has been selected through simple random
sampling procedure from three villages under Jamalpur Sadar upazila of Jamalpur
district which comprising of 40 farmers from each village. The study has employed
Cobb-Douglas stochastic frontier production function to estimate technical efficiency
for Boro rice cultivation. Result reveals that per hectare total cost of production was
Tk. 114931.68 per hectare. Gross returns was Tk. 120600.43 and net returns was Tk.
5668.75. Per hectare yields of Boro rice was found 6940 kg. Benefit Cost Ratio (BCR)
was found 1.05 which implied that one taka investment in Boro rice production
generated Tk. 1.05. The mean technical efficiency of the Boro rice was 87 percent.
Human labour, seeds, fertilizers, insecticides, irrigation and power tiller (for land
preparation) were important factors for production of Boro rice. Education, experience,
farm size and training has expected negative sign which can reduce the farmer’s
inefficiency in the study area. The study also identified some problems faced by the
Boro rice growers and suggested some recommendations to improve the present Boro
rice production
Innovation, human capital and economic growth: international evidence
No full textThis thesis empirically examines the roles of innovation and human capital in
improving economic growth for a large number of developed and developing countries. It
contains three essays. The first essay investigates the effects of R&D intensity and
technology transfer on total factor productivity growth. It also examines whether
productivity growth depends on human capital and its interaction with distance to the
technological frontier. Using several indicators of innovative activity and product variety,
the results suggest that R&D intensity has a significant direct and positive effect on
productivity growth only in high income OECD countries, whereas the same effect for
R&D-based absorptive capacity is only found in developing countries. Moreover, human
capital-based absorptive capacity is found to be weakly significant in developing countries.
Autonomous technology transfer is found to have a significant effect in stimulating
productivity growth in both groups of countries.
The second essay studies whether the contribution of human capital to productivity
growth depends on its composition and proximity to the technology frontier. Using
different levels of human capital data from several sources, the results indicate that the
growth-enhancing effects of skilled human capital increase with proximity to the
technology frontier only in high and medium income countries. Unskilled human capital
contributes more to growth in low income countries, as they move closer to the technology
frontier. Female workers with secondary education generate more productivity growth than
male workers in low income countries, whereas male workers with tertiary education
contribute more to productivity growth than female workers in high and medium income
countries. Mature workers with tertiary education are more growth-enhancing for high and
medium income countries, whereas younger workers with secondary education are more
growth improving for low income countries.
The third and final essay examines the joint effects of both the quantity and quality
of human capital in improving productivity growth. Using different measures of human
capital quantity and quality, the results suggest that the growth effects of educational
attainment can be significantly enhanced when the quality of schooling is improved. The
magnitude of the joint effect of quantity and quality is found to be dominated by
small class size and the performance in cognitive skills tests in science and mathematics.
The contribution of the quality-adjusted human capital is found to be stronger in
developing countries. Human capital is growth enhancing, but to gain a deeper insight one
needs to examine its composition and distinguish between quality and quantity
Méthodes d'apprentissage automatique à faible complexité pour la reconnaissance de gestes inter-sessions et inter-sujets à partir de HD-sEMG = Low-complexity machine learning methods for intersession/subject gesture recognition from HD-sEMG
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