We construct various new BPS states of D-branes preserving 8 supersymmetries. These include super Jackstraws (a bunch of scattered D- or (p, q)-strings preserving supersymmetries), and super waterwheels (a number of D2-branes intersecting at generic angles on parallel lines while preserving supersymmetries). Super D-Jackstraws are scattered in various dimensions but are dynamical with all their intersections following a common null direction. Meanwhile, super (p, q)-Jackstraws form a planar static configuration. We show that the SO(2) subgroup of SL(2, R), the group of classical S-duality transformations in IIB theory, can be used to generate this latter configuration of variously charged (p, q)-strings intersecting at various angles. The waterwheel configuration of D2-branes preserves 8 supersymmetries as long as the 'critical' Born-Infeld electric fields are along the common direction
Sule, L.; Rompas, P. T. D.
The utilization of water energy source is mainly used as a provider of electrical energy through hydroelectric power. The potential utilization of water flow energy is relatively small. The objective of this study is to know the best blade of Savonius waterwheel with various variables such as water discharge, blade number, and loading. The data used the efficiency of waterwheel, variation of blade number, variable water discharge, and loading in the shaft. The test results have shown that the performances of a top-water mill with the semicircular curve where the variation in the number of blades are 4, 6, and 8 at discharge and loading of 0.01587 m3/s and 1000 grams respectively were 9.945%, 13.929%, and 17.056% respectively. The blades number of 8 obtained the greatest performance. The more number of blades the greater the efficiency of the waterwheel Savonius.
Stan Yorke, using easy to follow text, diagrams and photographs, describes the various styles of mill and waterwheel and how they work. The book includes a list of restored mills which are open to the public.
Budiarso; Adanta, Dendy; Warjito; Siswantara, A. I.; Saputra, Pradhana; Dianofitra, Reza
Rapid economic and population growth in Indonesia lead to increased energy consumption, including electricity needs. Pico hydro is considered as the right solution because the cost of investment and operational cost are fairly low. Additionally, Indonesia has many remote areas with high hydro-energy potential. The overshot waterwheel is one of technology that is suitable to be applied in remote areas due to ease of operation and maintenance. This study attempts to optimize bucket dimensions with the available conditions. In addition, the optimization also has a good impact on the amount of generated power because all available energy is utilized maximally. Analytical method is used to evaluate the volume of water contained in bucket overshot waterwheel. In general, there are two stages performed. First, calculation of the volume of water contained in each active bucket is done. If the amount total of water contained is less than the available discharge in active bucket, recalculation at the width of the wheel is done. Second, calculation of the torque of each active bucket is done to determine the power output. As the result, the mechanical power generated from the waterwheel is 305 Watts with the efficiency value of 28%.
Las azudas de Larmahue: una singular manifestación del ingenio humano para regar cultivos en tierras de secano. / The norias or waterwheels of Larmahue, Chile: an unusual manifestation of the human struggle to irrigate crops in dry lands.
Carolina Quilodrán Rubio
Full Text Available Puesto a prueba desde tiempos inmemoriales, el ingenio humano ha creado verdaderas obras de arte para dar respuesta a condiciones adversas. Una prueba de ello son las azudas o ruedas de agua, fruto de la necesidad de conseguir un eficiente riego de los campos destinados al cultivo. Los babilonios ya supieron de sus beneficios. Otras culturas han enriquecido su diseño y perfeccionado su funcionamiento. Y en pleno valle central chileno se puede admirar, hoy en día, las azudas de Larmahue./ Put to test since the dawn of time, human ingenuity has created real works of art in response to adverse conditions. An example of that are the azudas or waterwheels, born from a necessity to obtain efficient irrigation of field crops. The Babylonians knew of their benefits. Other cultures enriched its design and perfected it and, nowadays, in the heart of the Chilean Central Valley you can admire the waterwheels of Larmahue.
The publication imparts information about the personal life and professional sphere of activity of J.A. Segner, Karl Küppers, Maximilian Neu, Hans Bunte, and Felix Meyer, as far as they were involved with the invention of devices for measuring gas flow, especially their involvement in testing the introduction of Rotameters into the medical field. The knowledge that the threat of deportation in October 1940, due to his Jewish background and in view of the politics of the National Socialists at the time, led to Maximilian Neu's committing suicide, is of added historical interest. Together with biographical details, the role played by the Institute of Research in Karlsruhe and the establishment of the Rotameter site in Aachen is presented. The historical outline finishes with a short report of the author's first experience with Rotameters at the Nuffeld Department of Anaesthetics, Oxford University during the Second World War and with his subsequent efforts to introduce Rotameters into anesthesia equipment design in the United States.
Comment on "Most computational hydrology is not reproducible, so is it really science?" by Christopher Hutton et al.: Let hydrologists learn the latest computer science by working with Research Software Engineers (RSEs) and not reinvent the waterwheel ourselves
Hut, R. W.; van de Giesen, N. C.; Drost, N.
The suggestions by Hutton et al. might not be enough to guarantee reproducible computational hydrology. Archiving software code and research data alone will not be enough. We add to the suggestion of Hutton et al. that hydrologists not only document their (computer) work, but that hydrologists use the latest best practices in designing research software, most notably the use of containers and open interfaces. To make sure hydrologists know of these best practices, we urge close collaboration with Research Software Engineers (RSEs).
Al-Jumaily, Khalil E. J.; Tawfi, Sinan Samir
A small hydroelectric power system of an undershot waterwheel was designed, constructed and experimented in the hydraulic channel which has a sluice gate as a small dam. The constructed waterwheel diameter could be changed from 0.4 m to 0.6 m at interval steps of 0.04 m. The number of blades of the constructed waterwheel could be changed from 9 to 12 to 18 and to 36 blades. By increasing the water mass flow rate from 0.341 to 1.765 kg/s at channel cross sectional area (12.75 cm 2 ), the undershot waterwheel generated power which increased to 0.201 Watt, the mechanical efficiency increased to more than 10.8%, and the electrical efficiency increased to more than 80.6%. But the channel efficiency was decreased to 10.9%. while the volumetric efficiency was fixed at 72.9%. The waterwheel efficiency 17.25 m 2 at fixed water mass flow rate (1.765kg/s), the undershot waterwheel generated power system decreased in the following. The generator output power from 0.201 to 0.067 Watt, the mechanical efficiency reduced to 26.7% and the electrical efficiency reduced 94.4% and increased the channel efficiency from 8.6% to 100%, the volumetric efficiency from 70.9% to 75.5%, and the waterwheel efficiency from 85.7%( to 91.3%. The transitional efficiency was fixed at 97.9%. The maximum overall efficiency of the small generated power system was 6.69% at the water head 15.45 cm. The output power was 0.18 Watt. these values obtained when the number of blades 36, number of revolutions per minute 57 rpm, waterwheel diameter 0.44 m, water mass flow rate 1.765 kg/s, and channel cross sectional area 12.75 cm 2 . The theoretical extrapolation of the waterwheel diameter to 2 m with water head of 5 m gives an output generated power of 675 Watt.(Author)
García-Deibe, Ana M; Portela-García, Cristina; Fondo, Matilde; Mota, Antonio J; Sanmartín-Matalobos, Jesús
A decanuclear Cd complex has been found as a carbonate-containing capsule. The structure strongly resembles a ten-blade waterwheel with a central carbonate ligand surrounded by two superimposed Cd(5)O(5) crowns with a pentagonal antiprism-like disposition. The capsule is doubly capped by two pentadentate perchlorate anions.
Gerkema, T.; Gostiaux, L.
In 1835, Gustave Coriolis derived the expression of a force acting in rotating systems, now known as the Coriolis force. His work was inspired by rotating devices such as waterwheels. However, the onerotating device that has always been with us is the Earth itself. Indeed, the earliest studies on
The increasing energy demand and the depletion of fossil fuel reserves caused the waterwheel crisis, it is necessary for innovation to generate alternative energy sources. One of the alternative energy is biogas which can be produced from solid waste of tofu production (SWTP). Utilization of solid waste of tofu production (SWTP) to produce biogas can reduce energy consumption from fossil fuels while reducing the accumulation of garbage because so far most of the solid waste of tofu production...
This Bachelor work deals with the exploitation of water power as a source of energy. The first part concentrates on the history of water exploitation as a source of energy. The second part deals with water mills and their reconstruction to hydraulic water plants. The third part deals with the construction of water-wheels and hydraulic water plants. The following parts deal with the hydro-electric plants and hydraulic water plants with the calculations of efficiency of their machinery.
Benabat Hierro, Yolanda; Pérez Macías, Juan Aurelio
En este trabajo se describe un pozo de noria hispanomusulmán de los alrededores de Niebla, se estudian los materiales cerámicos asociados a él, y se relaciona con la conducción conocida como los Caños de Niebla.______________________________In This work we study an islamic well with waterwheel near Niebla (Huelva, SW Spain). The pottery from this site is anlayzed and relacionated with the islamic waterworks called Caños de Niebla.
Tessmer, R.G. Jr.; Boyle, J.R.; Fish, J.H. III; Martin, W.A.
Wheeling electric power, the transmission of electricity not owned by an electric utility over its transmission lines, is a term not generally recognized outside the electric utility industry. Investigation of the term`s origin is intriguing. For centuries, wheel has been used to describe an entire machine, not just individual wheels within a machine. Thus we have waterwheel, spinning wheel, potter`s wheel and, for an automobile, wheels. Wheel as a verb connotes transmission or modification of forces and motion in machinery. With the advent of an understanding of electricity, use of the word wheel was extended to be transmission of electric power as well as mechanical power. Today, use of the term wheeling electric power is restricted to utility transmission of power that it doesn`t own. Cogeneration refers to simultaneous production of electric and thermal power from an energy source. This is more efficient than separate production of electricity and thermal power and, in many instances, less expensive.
Lu, Jing Tao; Brandbyge, Mads; Hedegard, Per
We derive and employ a semiclassical Langevin equation obtained from path integrals to describe the ionic dynamics of a molecular junction in the presence of electrical current. The electronic environment serves as an effective nonequilibrium bath. The bath results in random forces describing Joule...... heating, current-induced forces including the nonconservative wind force, dissipative frictional forces, and an effective Lorentz-type force due to the Berry phase of the nonequilibrium electrons. Using a generic two-level molecular model, we highlight the importance of both current-induced forces...... and Joule heating for the stability of the system. We compare the impact of the different forces, and the wide-band approximation for the electronic structure on our result. We examine the current-induced instabilities (excitation of runaway "waterwheel" modes) and investigate the signature...
Risk assessment is first explained. For example, for a loss of coolant accident at Sizewell B the estimate of the likelihood that radioactivity would be released involves three numbers:- the frequency of loss of coolant from the reactor; how often the safety pumps which would have to work in case of a loss of coolant have failed when tested; and the chance that the containment round the reactor will fail. As each risk number is small, the combined risk is very small. Using the same method of assessment the risk of an accident affecting public safety at the liquid gas plant on Canvey Island is 1000 larger, but still small and acceptable. Much time and money was spent on establishing the 1000 times lower risk of an accident affecting public safety at the Sizewell reactor. The risk assessment was however, finally accepted. Fast reactors are even safer than pressurised water reactors and use a renewable energy source; their development is strongly advocated. It is noted that the risks from a medieval water-wheel were enormous compared with nuclear risks today. (U.K.)
Körner, A.; Born, L.; Mader, A.; Sachse, R.; Saffarian, S.; Westermeier, A. S.; Poppinga, S.; Bischoff, M.; Gresser, G. T.; Milwich, M.; Speck, T.; Knippers, J.
Smart and adaptive outer façade shading systems are of high interest in modern architecture. For long lasting and reliable systems, the abandonment of hinges which often fail due to mechanical wear during repetitive use is of particular importance. Drawing inspiration from the hinge-less motion of the underwater snap-trap of the carnivorous waterwheel plant (Aldrovanda vesiculosa), the compliant façade shading device Flectofold was developed. Based on computational simulations of the biological role-model’s elastic and reversible motion, the actuation principle of the plant can be identified. The enclosed geometric motion principle is abstracted into a simplified curved-line folding geometry with distinct flexible hinge-zones. The kinematic behaviour is translated into a quantitative kinetic model, using finite element simulation which allows the detailed analyses of the influence of geometric parameters such as curved-fold line radius and various pneumatically driven actuation principles on the motion behaviour, stress concentrations within the hinge-zones, and actuation forces. The information regarding geometric relations and material gradients gained from those computational models are then used to develop novel material combinations for glass fibre reinforced plastics which enabled the fabrication of physical prototypes of the compliant façade shading device Flectofold.
Suprapty, B.; Malani, R.; Minardi, J.
East Kalimantan is a very rich area with water sources, in the form of river streams that branch to the remote areas. The conditions of natural potency like this become alternative solution for area that has not been reached by the availability of electric energy from State Electricity Company. The river water in selected location (catchment area) which is channelled to the canal, pipeline or penstock can be used to drive the waterwheel or turbine. The amount of power obtained depends on the volume/water discharge and headwater (the effective height between the reservoir and the turbine). The water discharge is strongly influenced by the amount of rainfall. Rainfall is the amount of water falling on the flat surface for a certain period measured, in units of mm3, above the horizontal surface in the absence of evaporation, run-off and infiltration. In this study, the prediction of rainfall is done in the area of East Kalimantan which has 13 watersheds which, in principle, have the potential for the construction of Micro Hydro Power Plant. Rainfall time series data is modelled by using AR (Auto Regressive) Model based on FIS (Fuzzy Inference System). The FIS structure of the training results is then used to predict the next two years rainfall.
Anak Agung Adhi Suryawan
Full Text Available Bali memiliki banyak sumber energi aliran air sungai atau saluran irigasi yang mempunyai debit aliran relatif kecil pada head yang rendah, dengan demikian Hydropower dapat memberikan solusi praktis terhadap masalah konservasi energi dan masalah lingkungan. Pada penelitian ini didesain model kincir sudu melengkung ke belakang (back curve vanes skala laboratorium, mengikuti kaidah-kaidah desain turbin air, dengan metode satu busur lingkaran, sehingga pengusaha bengkel nanti dapat membuat sudu kincir air dari potongan pipa besi. Data-data yang diamati adalah : kapasitas aliran (Qa, head (Ha, putaran kincir (n, pada setiap variasi beban, sudut aliran air masuk sudu, dan sudut kelengkungan sudu dengan demikian menjadi jelas karakteristik dari kincir air. Empat sudu yang diuji memiliki sudut kelengkungan sudu (? yang berbeda yaitu 10o, 20o, 30o dan 40o, sudut air masuk (?1 yaitu 2/5 ?, 3/5 ?, 4/5 ? dan 5/5 ?. Hasil penelitian menunjukkan bahwa unjuk kerja sudu lengkung ke belakang dengan besarnya sudut aliran air masuk sudu (?1 yang sesuai/sama dengan sudut kelengkungan sudu (? akan menghasilkan unjuk kerja yang paling baik. Empat sudu yang diuji pada konstan dan variasi kapasitas maka sudut kelengkungan sudu (? = 20o menunjukkan hasil terbaik. Semakin kecil sudut kelengkungan sudu maka unjuk kerja akan semakin baik dalam batas toleransi atas meningkatnya kerugian gesekan/hidrolis dari fluida kerja yang terjadi. Bali has many sources of river water streams or irrigation channels that have relatively small flow discharge at low head, thus Hydropower can provide practical solutions to energy conservation and environmental issues. In this research, the model is designed for the back curve vanes of laboratory scale, following the rules of water turbine design, with the method of one circular arc, so that the workshop entrepreneur can make the waterwheel from the iron pipe binder. The observed data are: flow capacity (Qa, head (Ha, rotation
about one hour with 3 times repeatation RPM 6,917 ± 7,83, angle velocity 0,72 ± 0,77, axis power 0,25 ± 0,27 Watt, accomodated rate of flow 0,0001533 ± 0,0001732 m3/s, kinetic energy 0,36 ± 0,42 Watt, and rate of pump efficiency 67,85%. The maximum high of output can reached by the pump is 1.52 m. This pump can rise water higher than the highest goosebeak on waterwheel and the efficiency is highest than the waterwheel. So, it can be used to irrigate the lands that position is above the water.
Is it restoration or reconciliation? California's experience restoring the Sacramento - San Joaquin River Delta provides lessons learned and pathways forward to sustain critical ecosystem functions and services in a highly managed riverine delta.
Viers, J. H.; Kelsey, R.
Reconciling the needs of nature and people in California's Sacramento - San Joaquin River Delta represents one of the most critical ecosystem management imperatives in western North America. Over 150 years the Delta has been managed for near-term human benefits and in the process 95% of riverine and deltaic wetlands have been lost throughout the region. Despite extensive land conversion and alteration of hydrological and physical processes, the Delta remains important habitat for migratory birds and is home to over 60% of California's native fish species. It is also the waterwheel for the state's vast water distribution network and is maintained by a system of constructed levees that are at risk from catastrophic failure due to sea level rise, floods, and/or seismic activity. Such a collapse would have dire consequences for > 25M humans and world's 10th largest economy that depend on its freshwater. Thus, the ultimate cost of this ecosystem alteration and simplification is a riverscape that is no longer reliable for nature or people. For 30 years, attempts to 'restore' Delta ecosystems and improve reliability have met with mixed results. For example, reconnection of floodplains to floodwaters has resulted in improved ecological health for native fishes and recharge to localized aquifers. Uncoordinated releases of discharges below dams, however, have resulted in diminished water quality and populations of indicator species. Attempts to create wildlife friendly farms have been countered by an increase in perennial agriculture and commensurate increases in irrigation water demand. From these lessons learned, we demonstrate three key components of a reconciled Delta that will be necessary in the future: 1) full restoration of critical habitats, reconnecting land and water to rebuild ecosystem function; 2) landscape redesign, incorporating natural and engineered infrastructure to create a biologically diverse, resilient landscape to support both agriculture and natural