98 research outputs found
Fluid dynamics influence on submerged palm leaflet vibrations
No full textThis study investigates the vibrational behavior of palm leaflets submerged under varying conditions in water, focusing on flexible cantilever beams made from a coke can material. The beams, with dimensions including a thickness of 0.102 mm, a density of 850 kg/m3, and a Young's modulus of 5 GPa, were subjected to controlled sinusoidal motion using a shaker. Laser Doppler vibrometry was employed to analyze the vibration characteristics. The experiments were conducted within a 150-l fluid tank to minimize wall effects, ensuring accurate flow dynamics near the oscillating structure. Standard room temperature conditions prevailed, with assumed fluid properties of density and dynamic viscosity. The results demonstrate that increasing the submerged length of the beam in water significantly reduced both its first mode frequency and quality factor. These changes primarily stemmed from fluid loading effects and heightened damping within the submerged environment. The surrounding fluid added mass and viscous resistance to the beam, altering its natural frequency and decreasing its ability to sustain high-quality vibrations. This research underscores the pivotal role of fluid-structure interaction in influencing the vibrational dynamics of submerged cantilever beams, highlighting implications for various engineering applications where such interactions are critical.</p
Another reason science and the imagination of modern India
No full text"Another Reason is a bold and innovative study of the intimate relationship between science, colonialism, and the modern nation. Gyan Prakash, one of the most influential historians of India writing today, explores in fresh and unexpected ways the complexities, contradictions, and profound importance of this relationship in the history of the subcontinent. He reveals how science served simultaneously as an instrument of empire and as a symbol of liberty, progress, and universal reason - and how, in playing these dramatically different roles, it was crucial to the emergence of the modern nation." "Throughout, Prakash draws on major and minor figures on both sides of the colonial divide, including Mahatma Gandhi, Jawaharlal Nehru, the nationalist historian and novelist Romesh Chunder Dutt, Prafulla Chandra Ray (author of A History of Hindu Chemistry), Rudyard Kipling, Lord Dalhousie, and John Stuart Mill."--BOOK JACKET
Study on hydraulic regenerative braking system used in hybrid
No full textThe consumption of fossil fuels is one of the biggest problems being faced by humankind presently. With the increase in the demand of fuel, as increasing productivity is the prime concern in day to day life, the natural resources are getting depleted at a faster pace and hence there arises the necessity to develop and innovate novel environmental friendly methods and technology that employs alternative energy source to power heavy moving vehicles and offroad machineries which are being employed in different terrains. Hydraulic Regenerative braking system is one of the most researched and progressive area currently being applied in various machineries to address the issue of energy regeneration during braking. It is an eminent branch of hybrid hydraulic technology, having vantage of maximum power density and the potentiality to accept the high frequencies of charging and discharging. Relatively lower energy density and complicated coordinating operation between two power source required a special energy, control strategy to maximize the fuel saving potential. This paper takes into account the scope, advantage, limitation and application of hydraulic hybrids regenerative braking system of hydraulic hybrids regenerative braking system.</p
Leakage and its effects in various hydraulics driven system
No full textThis paper brings forward the various leakages and its effects which are associated with hydraulic system. Leakage is the main gradual leak in fluid power system, which is usually caused by the impurity in the oil and wear of matching surfaces between parts and lead to the change of the gap value. It results in reduction of system flow as well as the loss of system pressure, resulting in the decreasing of overall system efficiency. In fluid power system, internal leakage may occur in various components such as gear pump, reversing valve and hydraulic cylinder and external leakage at the shaft seal or the connecting parts. Effect of leakage on system can be observed using sensors.</p
Experimental analysis of non-uniform cantilever beam in fluid with variable depth
No full textIn this work, we present the comprehensive study of uniform and non-uniform cantilever beams made of flexible coke can material with density 2700 kg/m3 and Young’s modulus 80.81GPa vibrating in water. The length, width and thickness of the uniform beam are taken as 5 cm, 2 cm and 0.102 mm. For non-uniform beams, the width of the fixed end of the beam is taken as 2 cm and free end width are taken as 3 cm for diverging section and 1 cm for converging section. The beams are excited using shaker and their vibration characteristics have been observed using the Laser Doppler Vibrometer (LDV). The fluid loading and dissipation effect due to water on first bending mode frequency and corresponding quality factor/damping ratio are analysed for the uniform and non-uniform vibrating cantilever beam as the wet portion of the beam increases from zero length to its full length. Finally, the results are compared with the frequencies and quality factor the beams vibrating in ambient air. It is found that the frequency of diverging beam is approximately 11.64 % less and for converging beam it is approximately 27.4 % higher than that of uniform cantilever beam. The quality factor which is inversely proportional to damping ratio is 78 % less in diverging beam and 27 % more in converging beam as compared to that of uniform beam. Finally, as the length of beam in water increases, both frequencies and quality factors reduce due to fluid loading and damping effect. It is also noticed that as the beams are completed submerged in water, both the frequencies and quality factor for converging beams are found to be more as compared to uniform and diverging beams.</p
Modelling and Analysis of the Hydraulic System Parameters Under Different Loading Conditions
No full textHydraulic systems are widely used in modern heavy machinery for their advantages, including high-power density, rapid response, load stiffness, controllability, stability, and ease of operation. These systems rely on hydraulic pumps, motors, and valves, utilizing pressurized fluid for efficient power generation and transmission. Hydraulic oil, with its incompressible nature, is commonly employed as the working fluid. This paper analyses the impact of leakage on a hydraulic system, focusing on a cylinder, pump, motor, valve, and relief valve. Using MATLAB, the simulation compares parameters such as flow, speed, acceleration, and pressure under different loads to assess leakage effects. Understanding hydraulic system behaviour under various loads optimizes operation and power transmission. Findings enhance hydraulic system design, aiding decision-making in leakage prevention and load management.</p
PID controller with feed forward estimation used for fault tolerant control of hydraulic system
No full textThe paper stresses on the designing and implementation of a nonlinear offline feed forward controller in association with a PID controller as a fault tolerant control measure for a closed loop hydraulic system. An off-line nonlinear feed forward control with proportional pressure relief valve (PRV) loading on the loading pump has been developed using the subsystem models without taking into considerations the oil compressibility, valve dynamics and leakages associated with various components of the hydraulic circuit. A PID feedback has been utilized in real-time to deal with the unmodeled features and the modelling approximations. The characteristics of the speed response are significantly influenced by the disturbances related to external torque, change in the input magnitude as well as system parameters like inertia load and supply pressure. The real-time control showed that the experimental and predicted closed–loop control performances justify each other quite well. Hence, the PID gains were estimated quite effectively with the help of the developed simulation tool here. The control model produced good agreement between the demanded and real-time speed response for various loading conditions such as step load, sinusoidal load, variable load, triangular load etc.</p
Distinguishing ’Sugar’, ’Gravel, ’Flowers’ and ’Fish’ mesoscale cloud patterns in the trades using cluster analysis
No full textIn this thesis we are interested in distinguishing patterns of mesoscale cloud patterns in the trades. Specifically, whether Sugar, Gravel, Fish and Flowers patterns can objectively be identified using physical quantities. For this purpose, we use cloud fraction data attained by the CORAL Ka-Band cloud radar at the Barbados Cloud Observatory during the boreal winter seasons of 2018, 2019 and 2020. These cloud fraction data represents the curves up until a height of 4 km for a given 6-hour interval of time. We do this to see if these clusters match up with the labels assigned to each cloud fraction curve obtained from a classification model used in Schulz (2021). Firstly, we map the cloud fraction curves onto points on a finite dimensional space using functional principal component analysis. We subsequently apply K-means, Gaussian Mixture Models and Mean Shift clustering onto the pre-processed dataset to identify any robust clusters. We have been able to attain robust Sugar-like clusters for K-means for 3 and 4 partitions and Mean Shift with bandwidth λ ≈ 585. This provides evidence that we are able to use cloud fraction data to distinguish Sugar. However, the same can not be said for Gravel, Fish and Flowers as we have not been able to identify them in our analysis. It is suggested for future research to do sensitivity analysis in the height interval of the cloud fraction data, that outliers are omitted and that the labeled data from Schulz (2021) are used instead of the mean and spread of the data pertaining to those labels.Applied Mathematics | Applied Physic
Correction:Idelalisib exposure before allogeneic stem cell transplantation in patients with follicular lymphoma: an EBMT survey
Full text linkThe article “Idelalisib exposure before allogeneic stem cell transplantation in patients with follicular lymphoma: an EBMT survey”, written by Leopold Sellner, Johannes Schetelig, Linda Koster, Goda Choi, Didier Blaise, Dietrich Beelen, Fabrizio Carnevale Schianca, Jakob Passweg, Urs Schanz, Emmanuel Gyan, Federica Sora, Nicolaus Kröger, Gerald. G. Wulf, Gwendolyn Van Gorkom, Jiri Mayer, Corentin Orvain, Jean Henri Bourhis, Pavel Jindra, Victoria Potter, Francesco Zallio, Elisabeth Vandenberghe, Stephen Robinson, Patrick J. Hayden, Ibrahim Yakoub-Agha, Silvia Montoto, Peter Dreger, on behalf of the European Society for Blood and Marrow Transplantation Lymphoma and Chronic Malignancies Working Parties, was originally published Online First without Open Access. After publication in volume 55, issue 12, page 2335–2338, the author decided to opt for Open Choice and to make the article an Open Access publication.</p
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