575 research outputs found

    Effect of Nitrogen Fertilizer on the Growth of Wheat in Competition with Fireweed (Kochia Scoparia)

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    An attempt was made to determine comparative effect of nitrogen fertilizer (NH4NO3) on growth and root development of wheat as influenced by various densities of fireweed (Kochia scoparia) under greenhouse conditions. 1. Fireweed grown alone did not show any significant differences in height due to density or fertilizer. 2. When fireweed was grown in association with a uniform stand of wheat, significant differences in height occurred among treatments (densities of fireweed) and among rates of nitrogen fertilization. 3. Nitrogen fertilizer did not significantly increase the growth of wheat when fireweed was present at two, four, and eight plants per phytometer. 4. Nitrogen at the rate of one hundred pounds per acre was better than fifty pounds which in turn increased the length of the roots significantly more than the control (no nitrogen). 5. Nitrogen application increased the dry matter of top growth of weeds when grown alone. 6. Dry matter yield of fireweed grown with wheat was also significantly influenced by densities of weeds. 7. Nitrogen fertilizer increased dry yield of fireweed in presence of wheat crop. 8. Wheat dry matter yield was decreased in presence of fireweed densities but nitrogen fertilizer did not increase dry yield of wheat. 9. One hundred pounds of nitrogen per acre was significantly better than fifty pounds which in turn significantly increased dry matter of roots more than the control. 10. In general, shoot-root ratio decreased in all treatments with added nitrogen

    Simulation of Five Level Diode Clamped Multilevel Inverter

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    The power electronics device which converts DC power to AC power at required output voltage and frequency level is known as inverter. The voltage source inverters produce an output voltage or a current with levels either 0 or +ve or-ve V dc. They are known as two-level inverters. Multilevel inverter is to synthesize a near sinusoidal voltage from several levels of dc voltages. Multilevel inverter has advantage like minimum harmonic distortion. Multi-level inverters are emerging as the new breed of power converter options for high power applications. They typically synthesize the stair-case voltage waveform (from several dc sources) which has reduced harmonic content. Multi-level inverters have many attractive features, high voltage capability, reduced common mode voltages near sinusoidal outputs, low dv/dt, and smaller or even no output filter; sometimes no transformer is required at the input side, called the transformer-less solution, making them suitable for high power applications In this paper a 5-level Diode clamped multilevel inverter is developed by IGBTS using Simulink. Gating signals for these IGBTS have been generated by designing comparators. In order to maintain the different voltage levels at appropriate intervals, the conduction time intervals of IGBT have been maintained by controlling the pulse width of gating pulses[6] (by varying the reference signals magnitude of the comparator). The simulation results for 5-level and THD for the output have been identified by MATLAB/SIMULINK

    Design and Analysis of Multilevel Inverter with Reduced Number of Switches using Multicarrier SPWM Techniques

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    Multi-level inverter has been widely accepted for high voltage applications. Their performance is highly superior to that of conventional two level inverter due to reduced harmonic distortion, lower electromagnetic interference and higher dc link voltages. Multi-level inverter (MLI) has some disadvantages such as increased number of components, complex pulse width modulation control method, and voltage-balancing problem. In order to increase the level of the output, the numbers of switches are increased and losses and complexity also increased. Hence to reduce these losses and complexity, a new topology is designed in this project i.e. Multi-level inverter (MLI) with reduced number of switches. A new inverter topology has been proposed which has superior features over conventional topologies in terms of the required power switches and isolated dc supplies, control requirements and reliability. In the mentioned topology, the switching operation is separated into high- and low-frequency parts. Design and simulation analysis of new 7 level inverter topology with multicarrier spwm techniques is presented in this project thesis using MATLAB/SIMULIN

    Dynamics and ‘normal stress’ evaluation of dilute suspensions of periodically forced prolate spheroids in a quiescent Newtonian fluid at low Reynolds numbers

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    The problem of determining the force acting on a particle in a fluid where the motion of the fluid and the particle is given has been considered in some detail in the literature. In this work, we propose an example of a new class of problems where, the fluid is quiescent and the effect of an external periodic force on the motion of the particle is determined at low non-zero Reynolds numbers. We present an analysis of the dynamics of dilute suspensions of periodically forced prolate spheroids in a quiescent Newtonian fluid at low Reynolds numbers including the effects of both convective and unsteady inertia. The inclusion of both forms of inertia leads to a nonlinear integro — differential equation which is solved numerically for the velocity and displacement of the individual particle. We show that a ‘normal stress’ like parameter can be evaluated using standard techniques of Batchelor. Hence this system allows for an experimentally accessible measurable macroscopic parameter, analogous to the ‘normal stress’, which can be related to the dynamics of individual particles. We note that this ‘normal stress’ arises from the internal fluctuations induced by the periodic force. In addition, a preliminary analysis leading to a possible application of separating particles by shape is presented. We feel that our results show possibilities of being technologically important since the ‘normal stress’ depends strongly on the controllable parameters and our results may lead to insights in the development of active dampeners and smart fluids. Since we see complex behaviour even in this simple system, it is expected that the macroscopic behaviour of such suspensions may be much more complex in more complex flows

    Men and women from the STRIDE clinical trial: An assessment of stimulant abstinence symptom severity at residential treatment entry

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    Background and Objectives Gender‐specific factors associated with stimulant abstinence severity were examined in a stimulant abusing or dependent residential treatment sample (N = 302). Method Bivariate statistics tested gender differences in stimulant abstinence symptoms, measured by participant‐reported experiences of early withdrawal. Multivariate linear regression examined gender and other predictors of stimulant abstinence symptom severity. Results Women compared to men reported greater stimulant abstinence symptom severity. Anxiety disorders and individual anxiety‐related abstinence symptoms accounted for this difference. African American race/ethnicity was predictive of lower stimulant abstinence severity. Discussion and Conclusions Women were more sensitive to anxiety‐related stimulant withdrawal symptoms. Scientific Significance Clinics that address anxiety‐related abstinence symptoms, which more commonly occur in women, may improve treatment outcome. (Am J Addict 2015;XX:XX –XX

    Properties of cellulose/Thespesia Lampas short fibers bio-composite films

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    Abstract: Cellulose was dissolved in pre cooled environment friendly solvent (aq.7% sodium hydroxide+12% urea) and regenerated with 5%H2SO4 as coagulation bath. Using cellulose as matrix and alkali treated short natural fibers extracted from the newly identified Thespesia Lampas plant as reinforcement, the green composite films were prepared. The effect of fiber loading on the tensile properties and thermal stability was studied. The fractographs indicated better interfacial bonding between the fibers and cellulose. The crystallinity of the composite films was found to be lower than the matrix and decreased with increasing fiber content. In spite of better interfacial bonding, the tensile properties of the composites were found to be lower than those of the matrix and decreased with increasing fiber content and this behavior was attributed to the random orientation of the fibers in the composites. The thermal stability of the composite films was higher than the matrix and increased with fiber content

    Methyl N-({[2-(2-meth­oxy­acetamido)-4-(phenyl­sulfan­yl)phen­yl]amino}[(meth­oxy­carbonyl)imino]methyl)carbamate

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    In the title compound, C20H22N4O6S, the phenyl and benzene rings form a dihedral angle of 58.75 (5)°. Intra­molecular N—H⋯O and N—H⋯N hydrogen bonds generate two S(6) and one S(7) ring motif, respectively. In the crystal, mol­ecules are linked via N—H⋯O, N—H⋯N, C—H⋯S and C—H⋯O hydrogen bonds, forming two-dimensional networks parallel to the bc plane

    (E)-1-(4,4′′-Difluoro-5′-meth­oxy-1,1′:3′,1′′-terphenyl-4′-yl)-3-(6-meth­oxy­naphthalen-2-yl)prop-2-en-1-one

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    In the title compound, C33H24F2O3, the central benzene ring makes dihedral angles of 44.71 (10), 47.80 (10) and 63.68 (9)° with the two fluoro-substituted benzene rings and the naphthalene ring system, respectively. In the crystal, mol­ecules are connected via inter­molecular C—H⋯F and C—H⋯O hydrogen bonds. Furthermore, the crystal structure is stabilized by weak C—H⋯π and π–π inter­actions [centroid–centroid distance = 3.6816 (13) Å]
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