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1
Massaq, Zakaria, Abdelouahed Abounada, and Mohamed Ramzi. "Fuzzy and predictive control of a photovoltaic pumping system based on three-level boost converter." Bulletin of Electrical Engineering and Informatics 10, no. 3 (2021): 1183–92. http://dx.doi.org/10.11591/eei.v10i3.2605.
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In this work, an efficient control scheme for a double stage pumping system is proposed. On the DC side, a three-level boost converter is employed to maximize the photovoltaic power and to step-up the DC-link voltage. For maximum power point tracking, the classical incremental conductance method is substituted by a fuzzy logic controller. The designed controller estimates the optimal step size which speeds up the tracking process and improves the accuracy of the extracted photovoltaic power. Afterwards, the voltages across the three-level boost converter (TLBC) capacitors are balanced by phase shifting the applied duty ratios. On the motor pump side, a two-level inverter drives the motor pump with the cascaded nonlinear predictive control. The predictive controller is preferred over the conventional field-oriented control because it accelerates the torque response and resists to the change of the engine parameters. The designed controllers are evaluated using MATLAB/Simulink, and compared with the conventional controllers (incremental conductance algorithm and field-oriented control). The robust control scheme of the entire system has increased the hydraulic power by up to 23% during the system start-up and up to 10% in steady state.
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Gallagher, John, and Laurence W. Gill. "The Life Cycle Environmental Performance of On-Site or Decentralised Wastewater Treatment Systems for Domestic Homes." Water 13, no. 18 (2021): 2542. http://dx.doi.org/10.3390/w13182542.
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There is little knowledge regarding the environmental sustainability of domestic on-site or decentralised wastewater treatment systems (DWWTS). This study evaluated six unique life cycle environmental impacts for different DWTTS configurations of five conventional septic tank systems, four packaged treatment units, and a willow evapotranspiration system. Similar freshwater eutrophication (FE), dissipated water (DW), and mineral and metal (MM), burdens were noted between the packaged and conventional system configurations, with the packaged systems demonstrating significantly higher impacts of between 18% and 56% for climate change (CC), marine eutrophication (ME), and fossils (F). At a system level, higher impacts were observed in systems requiring (i) three vs. two engineered treatment stages, (ii) a larger soil percolation trench area, and (iii) pumping of effluent. The evapotranspiration system presented the smallest total environmental impacts (3.0–10.8 lower), with net benefits for FE, ME, and MM identified due to the biomass (wood) production offsetting these burdens. Further analysis highlighted the sensitivity of results to biomass yield, operational demands (desludging or pumping energy demands), and embodied materials, with less significant impacts for replacing mechanical components, i.e., pumps. The findings highlighted the variation in environmental performance of different DWTTS configurations and indicated opportunities for design improvements to reduce their life cycle impacts.
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Meaški, Hrvoje, Ranko Biondić, Jelena Loborec, and Dijana Oskoruš. "The Possibility of Managed Aquifer Recharge (MAR) for Normal Functioning of the Public Water-Supply of Zagreb, Croatia." Water 13, no. 11 (2021): 1562. http://dx.doi.org/10.3390/w13111562.
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With its quantities of groundwater, the Zagreb aquifer is an irreplaceable water-supply resource that forms the basis of the water-supply of Zagreb, the capital and largest city of the Republic of Croatia. The depth of the Zagreb aquifer system is about 100 m at the deepest part, and the two main aquifers of the aquifer system can be separated vertically by low-permeable clay deposits. In the area of the Zagreb aquifer, there are several active and reserve public water-supply sites, the largest of which are Mala Mlaka and Petruševec. The groundwater level of the Zagreb aquifer is directly related to the water levels of the Sava River, so any erosive change in the Sava riverbed decreases the groundwater levels in the aquifer. In the last 50 years, the groundwater levels in the Zagreb aquifer have decreased significantly, being most pronounced in the area of the Mala Mlaka water-supply site. This has affected the normal functioning of the public water-supply because the suction baskets of the pumps in the dug wells at the Mala Mlaka water-supply site occasionally remain partially or completely in the unsaturated aquifer zone during low groundwater levels, which reduces capacity or prevents pumping from these water-supply facilities. Immediately next to the Mala Mlaka water-supply site is the Sava-Odra Canal, which was built to protect Zagreb from flooding and into which the Sava River flows when its flow rate exceeds 2350 m3/s. This reduces the flow rate of the Sava River near Zagreb and the possibility of flooding urban areas. To prevent problems with groundwater levels at the Mala Mlaka water-supply facilities and to enable normal water-supply, even in extremely dry periods, several variants of managed aquifer recharge (MAR) are proposed here. In order to determine the optimal solution for MAR and to enable the normal functioning of one of the main sites of water-supply in the Zagreb water-supply system. Groundwater flow for the period of 2006 to 2010 was simulated for six different variants of MAR. One assumes a constant potential in the Sava-Odra Canal, three are related to recharge from the Sava-Odra Canal with different backwater levels in the infiltration facility (elevations of 114, 114.5, and 115 m a.s.l.), and two with three absorption wells upstream of the Mala Mlaka water pumping station (injection of 300 L/s each and 500 L/s each). The most favorable method to recharge artificially the Zagreb aquifer near the Mala Mlaka pumping station is achieved with an infiltration facility using an elevation of 115 m a.s.l. The use of such a facility will enable the smooth operation of the water pumping station and the possibility of increasing the pumping quantities at the Mala Mlaka water pumping station for the future development of the area.
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Ye, S., Y. Luo, J. Wu, P. Teatini, H. Wang, and X. Jiao. "Three dimensional numerical modeling of land subsidence in Shanghai." Proceedings of the International Association of Hydrological Sciences 372 (November 12, 2015): 443–48. http://dx.doi.org/10.5194/piahs-372-443-2015.
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Abstract. Shanghai city has been suffering land subsidence caused by overly exploitation of ground water since 1921, which is a serious problem for this coastal city with altitude of 2.2–4.8 m above mean sea level. The largest cumulative land subsidence amounted to 2.6 m in the downtown area. Measures to decrease the ground water exploitation, change the pumping aquifers, and increase aquifer artificial recharge have been used to mitigate land subsidence since 1961. It is necessary to develop a proper numerical model to simulate and predict land subsidence. In this study, a decoupled three-dimensional (3-D) finite element land subsidence model including a 3-D ground water flow model and a 3-D geo-mechanical model was developed to simulate the 3-D deformation of the aquifer systems in the center area of Shanghai. The area of downtown Shanghai is 660 km2, with 10 million inhabitants, dense high buildings, and 11 metro lines. The simulation spans the period from 1979 to 1995. Two different assumptions have been tested on the side boundary, i.e., precluding the three components of the displacement, or assuming a free-displacement condition. The distribution of calculated land subsidence and horizontal displacements in different aquifers was analyzed. The computed vertical displacement fitted well with the available observations. It has been verified that the two different assumptions on the lateral boundaries in the geo-mechanical model caused different results just limited on nodes close to boundary. The developed 3-D land subsidence model is reasonable and can be used to simulate and predict 3-D movement of aquifer systems in the center area of Shanghai, which could provide scientific support to local government in controlling land subsidence and differential movements of the land surface.
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Autran, J. L., F. Djahli, B. Balland, C. Plossu, and L. M. Gaborieau. "Three-level charge pumping on submicronic MOS transistors." Solid State Communications 84, no. 6 (1992): 607–11. http://dx.doi.org/10.1016/0038-1098(92)90200-s.
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Davidson, J. H., W. T. Carlson, and W. S. Duff. "Impact of Component Selection and Operation on Thermal Ratings of Drain-Back Solar Water Heaters." Journal of Solar Energy Engineering 114, no. 4 (1992): 219–26. http://dx.doi.org/10.1115/1.2930009.
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A half-factorial, two-level experimental design is used to determine the effects of changes in collector area, storage tank volume, collector flow rate, recirculation flow rate, and storage tank design on thermal rating of a solar drain-back water heating system. Experimental ratings are determined in accordance with the Solar Rating and Certification Corporation guidelines. Storage tank design is varied by using a stratification manifold in place of the standard drop tube. Variations in other component sizes and operating factors are based on current industry standards. Statistical analyses indicate that a change in collector area accounts for nearly 90 percent of the variation in heat output. Doubling collector area from 2.78 m2 to 5.56 m2 increases delivered solar energy by 31 percent. Use of a stratification manifold increases the delivery of solar energy by six percent. Doubling collector flow rate from 0.057 to 0.114 1/s increases solar output by approximately three percent; however, the increase in pumping energy outweighs the benefits of increasing collector flow rate. The effects of recirculation flow rate and tank volume are obscured by experimental error.
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Militaru, L., P. Masson, and G. Guegan. "Three level charge pumping on a single interface trap." IEEE Electron Device Letters 23, no. 2 (2002): 94–96. http://dx.doi.org/10.1109/55.981317.
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Kivi, M. J., and S. Taylor. "SHE injection as studied by three level charge pumping." Microelectronics Journal 27, no. 7 (1996): 687–91. http://dx.doi.org/10.1016/0026-2692(96)00060-2.
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Plant, R. S., and S. E. Belcher. "Numerical Simulation of Baroclinic Waves with a Parameterized Boundary Layer." Journal of the Atmospheric Sciences 64, no. 12 (2007): 4383–99. http://dx.doi.org/10.1175/2007jas2269.1.
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Abstract A dry three-dimensional baroclinic life cycle model is used to investigate the role of turbulent fluxes of heat and momentum within the boundary layer on midlatitude cyclones. Simulations are performed of life cycles for two basic states: with and without turbulent fluxes. The different basic states produce cyclones with contrasting frontal and mesoscale flow structures. The analysis focuses on the generation of potential vorticity (PV) in the boundary layer and its subsequent transport into the free troposphere. The dynamic mechanism through which friction mitigates a barotropic vortex is that of Ekman pumping. This has often been assumed to also be the dominant mechanism for baroclinic developments. The PV framework highlights an additional, baroclinic mechanism. Positive PV is generated baroclinically due to friction to the northeast of a surface low and is transported out of the boundary layer by a cyclonic conveyor belt flow. The result is an anomaly of increased static stability in the lower troposphere, which restricts the growth of the baroclinic wave. The reduced coupling between lower and upper levels can be sufficient to change the character of the upper-level evolution of the mature wave. The basic features of the baroclinic damping mechanism are robust for different frontal structures, with and without turbulent heat fluxes, and for the range of surface roughness found over the oceans.
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Zhu, Wu, Xue-qi Zhang, Zhan-ke Liu, and Qian Zhu. "Spatiotemporal Characterization of Land Subsidence in Guandu (China) Revealed by Multisensor InSAR Observations." Journal of Sensors 2020 (October 15, 2020): 1–13. http://dx.doi.org/10.1155/2020/8855364.
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Excessive groundwater exploitation has brought about severe ground subsidence in Guandu (China), threatening the stability of urban infrastructure. Mapping of the spatiotemporal variations of ground deformation is urgently needed for disaster prevention and mitigation. In this study, multisensor interferometric synthetic aperture radar (InSAR) observations were applied to Guandu to derive the time series deformation from 2007 to 2019. The annual deformation velocity revealed three severe subsiding regions in Guandu. Based on the ascending and descending Sentinel-1 images with overlapping temporal and spatial coverage, two-dimensional vertical and horizontal east–west deformation was calculated and indicated that the deformation in Guandu was dominated by vertical direction. After connecting the multisensor results, long-term ground deformation spanning from January 9, 2007, to September 1, 2019, was produced and showed that the north subsiding region experienced fast followed by slow subsidence, whereas the south subsiding region experienced slow followed by fast subsidence. This difference was due to the changes of groundwater pumping centers and rates. The cumulative maximum subsidence reached 400 mm during the period of 2007–2019. The similar variations in temporal domain between the change of groundwater level and ground deformation suggested that groundwater exploitation accounted for the severe subsidence in Guandu. Our results may provide scientific evidence regarding the sound management of groundwater exploitation to mitigate potential damage to infrastructure and the environment.
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Saks, N. S., and M. G. Ancona. "Determination of interface trap capture cross sections using three-level charge pumping." IEEE Electron Device Letters 11, no. 8 (1990): 339–41. http://dx.doi.org/10.1109/55.57927.
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Sellami, M., M. Bouchemat, M. Kahouadji, and F. Djahli. "Characterization of interface traps on MOS transistor submicronic by the three level charge pumping." Journal de Physique IV (Proceedings) 124 (May 2005): 321–25. http://dx.doi.org/10.1051/jp4:2005124047.
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Abd-Elaty, Ismail, Martina Zeleňáková, Katarína Krajníková, and Hany Abd-Elhamid. "Analytical Solution of Saltwater Intrusion in Costal Aquifers Considering Climate Changes and Different Boundary Conditions." Water 13, no. 7 (2021): 995. http://dx.doi.org/10.3390/w13070995.
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Groundwater contamination due to saltwater intrusion (SWI) has an extreme effect on freshwater quality. Analytical and numerical models could be used to investigate SWI. This study aims to develop an analytical solution to investigate SWI into coastal aquifers which was applied to a real case study at the Middle Nile Delta aquifer (MNDA). The study presented a new formula to predict the difference in depth of freshwater to seawater interface due to a change in boundary conditions. A Computer Program for Simulation of Three-Dimensional Variable-Density Ground-Water Flow and Transport (SEAWAT) is used for groundwater flow simulation and SWI and the results compared with the developed analytical solution. Four scenarios are considered in the study, including; the sea-level rise (SLR), reduction in recharge, over abstraction, and combination after 50 years (2070). The analytical solution gave good results compared to the numerical one where Equiline 1 intruded to 103 and 101.66 km respectively at the base case. The results also gave a good agreement between numerical and the analytical solution for SLR due to climate changes by 52.80 cm where the Equiline 1 reached to 105 and 103.45 km. However, the reduction in aquifer recharge by 18.50% resulted in an intrusion for the Equiline-1 to 111 and 108.25 km from the shoreline. Over pumping due to the increase in population by 89% has increased the SWI to reach 121,110.31 km, while it reached 131 and 111.32 km at a combination of the three scenarios, which represents the highest threatening scenario. Also, the difference between the two solutions reached 1.30%, 1.48%, 2.48%, 8.84%, and 15.02%, respectively for the base case and four scenarios. For the current case study, the analytical model gave good results compared to the numerical one, so that the analytical solution is recommended for similar studies, which could save the time and capabilities of computer required for the numerical solutions.
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Kim, Kee-Jong, and Ohyun Kim. "Identification of Grain-Boundary Trap Properties Using Three-Level Charge-Pumping Technique in Polysilicon Thin-Film Transistors." Japanese Journal of Applied Physics 36, Part 1, No. 3B (1997): 1394–97. http://dx.doi.org/10.1143/jjap.36.1394.
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Autran, Jean-Luc, Bernard Balland, and Daniel Babot. "Three-level charge pumping study of radiation-induced defects at SiSiO2 interface in submicrometer MOS transistors." Journal of Non-Crystalline Solids 187 (July 1995): 211–15. http://dx.doi.org/10.1016/0022-3093(95)00140-9.
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Fořt, Ivan, Václav Machoň, Jiří Hájek, and Eva Fialová. "Liquid circulation in a cylindrical baffled vessel of high height/diameter ratio with two impellers on the same shaft." Collection of Czechoslovak Chemical Communications 52, no. 11 (1987): 2640–53. http://dx.doi.org/10.1135/cccc19872640.
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The paper deals with the experimental study of the indicating particle circulation in a liquid mechanically agitated with two high-speed impellers (two standard turbine impellers or a lower standard turbine and upper six inclined (at 45°) plane blade impeller) on the same shaft in a slender vessel (its height equals double of the vessel diameter) equipped with four radial baffles at its walls under the turbulent flow regime of agitated charge. The visual method of observation of the indicating particle is used to investigate the model system. Four types of the particle circulation are examined: its circulation in the lower part of the system (pumping effect of the lower impeller), its circulation in the upper part of the system (pumping effect of the upper impeller), and the exchangeable circulation between the upper and lower part of the system and vice versa. It follows from the obtained average data of the above-mentioned circulations that the homogeneous circulation of charge in the whole system is reached providing the vertical distance of the high-speed impellers is equal to at least double of their diameter, their pumping capacities being approximately double compared to those reached in the system with one impeller where the off-bottom liquid level height is equal to the vessel diameter. It follows from the comparison of two arrangements, when the upper high-speed impeller pumps liquid either upwards or downwards, that the homogeneous circulation of all the charge agitated is attained in the first of both the cases compared.
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Ali Ben Fathallah, M., A. Ben Othman, and M. Besbes. "Stabilizing a DC Motor Speed of Photovoltaic Pumping System Using a Super Capacitor and Fuzzy Logic Controller." Mekhatronika, Avtomatizatsiya, Upravlenie 20, no. 11 (2019): 669–76. http://dx.doi.org/10.17587/mau.20.669-676.
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In this paper, two issues are discussed in a PV pumping system. Firstly, an evaluation of super capacitor is studied to reassure the storage of electrical energy and solve the intermittence problem of photovoltaic energy production in dark periods. Secondly, a fuzzy logic controller (FLC) is proposed to stabilize, on the one hand, the DC motor speed around a preferred level by the control of duty cycle of DC buck boost converter. On the other hand, FLC serves to control the charge and discharge of super capacitor according to the sunlight levels and its state of charge. In this framework, a complete photovoltaic pumping system model is simulated in MATLAB Simulink to discuss the run results at different levels of sunshine.
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Freedhoff, Helen S. "Cooperative fluorescence by three-level atoms in a strong excitation field." Canadian Journal of Physics 63, no. 1 (1985): 114–21. http://dx.doi.org/10.1139/p85-018.
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When a system of two-level atoms interacts with a very intense field, the phenomena associated with superradiance do not appear in the fluorescent radiation. The question has been raised, "Can pumping by an intense field inhibit the occurrence of superradiance in the fluorescence of a system of three-level atoms to the third (nonresonant) level?" In this paper, we calculate the fluorescence spectrum of 2 three-level atoms. We find that superradiance, while absent in that part of the radiation corresponding to resonance fluoresence, is present in the radiation to the nonresonant level.
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Xiao-Jie Yuan, M. Kivi, S. Taylor, and P. Hurley. "Effects of Fowler-Nordheim stress on interface trap density and emission cross sections in n-MOSFETs studied by three-level charge pumping." IEEE Electron Device Letters 17, no. 5 (1996): 239–41. http://dx.doi.org/10.1109/55.491841.
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Nocera, Alberto, Carmine Antonio Perroni, Vincenzo Marigliano Ramaglia, and Vittorio Cataudella. "Charge and heat transport in soft nanosystems in the presence of time-dependent perturbations." Beilstein Journal of Nanotechnology 7 (March 18, 2016): 439–64. http://dx.doi.org/10.3762/bjnano.7.39.
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Background: Soft nanosystems are electronic nanodevices, such as suspended carbon nanotubes or molecular junctions, whose transport properties are modulated by soft internal degrees of freedom, for example slow vibrational modes. Effects of the electron–vibration coupling on the charge and heat transport of soft nanoscopic systems are theoretically investigated in the presence of time-dependent perturbations, such as a forcing antenna or pumping terms between the leads and the nanosystem. A well-established approach valid for non-equilibrium adiabatic regimes is generalized to the case where external time-dependent perturbations are present. Then, a number of relevant applications of the method are reviewed for systems composed by a quantum dot (or molecule) described by a single electronic level coupled to a vibrational mode. Results: Before introducing time-dependent perturbations, the range of validity of the adiabatic approach is discussed showing that a very good agreement with the results of an exact quantum calculation is obtained in the limit of low level occupation. Then, we show that the interplay between the low frequency vibrational modes and the electronic degrees of freedom affects the thermoelectric properties within the linear response regime finding out that the phonon thermal conductance provides an important contribution to the figure of merit at room temperature. Our work has been stimulated by recent experimental results on carbon nanotube electromechanical devices working in the semiclassical regime (resonator frequencies in the megahertz range compared to an electronic hopping frequency of the order of tens of gigahertz) with extremely high quality factors. The nonlinear vibrational regime induced by the external antenna in such systems has been discussed within the non-perturbative adiabatic approach reproducing quantitatively the characteristic asymmetric shape of the current–frequency curves. Within the same set-up, we have proved that the antenna is able to pump sufficient charge close to the mechanical resonance making single-parameter adiabatic charge pumping feasible in carbon nanotube resonators. The pumping mechanism that we observe is different from that acting in the two parameter pumping and, instead, it is based on an important dynamic adjustment of the mechanical motion of the nanotube to the external drive in the weakly nonlinear regime. Finally, stochastic forces induced by quantum and thermal fluctuations due to the electron charging of the quantum dot are shown to affect in a significant way a Thouless charge pump realized with an elastically deformable quantum dot. In this case, the pumping mechanism is also shown to be magnified when the frequency of the external drive is resonant with the proper frequency of the deformable quantum dot. In this regime, the pumping current is not strongly reduced by the temperature, giving a measurable effect. Conclusion: Aim of this review has been to discuss common features of different soft nanosystems under external drive. The most interesting effects induced by time-dependent perturbations are obtained when the external forcing is nearly resonant with the slow vibrational modes. Indeed, not only the external forcing can enhance the electronic response, but it also induces nonlinear regimes where the interplay between electronic and vibrational degrees of freedom plays a major role.
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WANG, HUI, HONG-TAO ZHANG, and ZHI-PING WANG. "OPTICAL BISTABILITY VIA INCOHERENT PUMPING FIELDS IN SEMICONDUCTOR QUANTUM WELLS." Modern Physics Letters B 25, no. 02 (2011): 97–108. http://dx.doi.org/10.1142/s0217984911025511.
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Under the non-resonant condition, we investigated the optical bistability (OB) in a three-level quantum well system inside a unidirectional ring cavity. We find that the incoherent pumping fields and the quantum interference induced by incoherent pumping fields can affect the optical bistability dramatically, which can be used to manipulate efficiently the threshold intensity and the hysteresis loop. These results are achieved by applying the two incoherent pumping fields, so they are very different from the conventional schemes that coherent driving fields are used to control the optical bistability. Thus, it may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science.
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Kylafis, Nikolaos D. "Theory of Astronomical Masers." Symposium - International Astronomical Union 129 (1988): 223–30. http://dx.doi.org/10.1017/s0074180900134527.
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The theory of astronomical masers is reviewed. As with laboratory masers, masing occurs when a transition between two energy levels of a molecule exhibits inverted populations. In order to present the basic concepts about masers, an idealized two-level system is used. The exact energy level structure is taken into account later on when the pumping of specific molecules is discussed. Unlike laboratory masers, where the radiation must be bounced between two mirrors to accumulate gain, the propagation of radiation in astronomical masers is a lot simpler. This is because astronomical masers are single-pass and broadband. Thus, the main theoretical effort has concentrated on inventing efficient mechanisms that produce population inversion. Specific pumping mechanisms for the three molecules (H2O, SiO, and OH) that exhibit strong masing are presented and their ability to explain the observations is discussed.
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Bauza, D. "Rigorous analysis of two-level charge pumping: Application to the extraction of interface trap concentration versus energy profiles in metal–oxide–semiconductor transistors." Journal of Applied Physics 94, no. 5 (2003): 3239–48. http://dx.doi.org/10.1063/1.1595138.
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Kurzyna, Marcin, and Tomasz Kwapiński. "Electron Pumping and Spectral Density Dynamics in Energy-Gapped Topological Chains." Applied Sciences 11, no. 2 (2021): 772. http://dx.doi.org/10.3390/app11020772.
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Electron pumping through energy-gapped systems is restricted for vanishing local density of states at the Fermi level. In this paper, we propose a topological Su–Schrieffer–Heeger (SSH) chain between unbiased leads as an effective electron pump. We analyze the electron transport properties of topologically trivial and nontrivial systems in the presence of external time-dependent forces in the form of one-Gaussian or two-Gaussian perturbations (train impulses). We have found that the topologically trivial chain stands for much better charge pump than other normal or nontrivial chains. It is important that, during the perturbation, electrons are pumped through the mid-gap temporary states or through the induced sidebands states outside the energy gap. We also analyze the local density of states dynamics during the quench transition between different topological phases of the SSH chain. It turns out that after the quench, the edge topological states migrate through other sites and can temporarily exist in a topologically trivial part of the system. The tight-binding Hamiltonian and the evolution operator technique are used in our calculations.
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Vick, B. D., and R. N. Clark. "Performance of Wind-Electric and Solar-PV Water Pumping Systems for Watering Livestock." Journal of Solar Energy Engineering 118, no. 4 (1996): 212–16. http://dx.doi.org/10.1115/1.2871780.
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The water pumping performance of two wind-electric systems is compared to the water pumping performance of two solar-PV systems. The wind-electric systems were rated at 1.0 kW and 1.5 kW at a wind speed of about 12 m/s, and the rotor diameters were 2.75 m and 3.05 m, respectively. The solar-PV systems were rated at 0.1 kW and 0.9 kW at a radiation level of about 1000 W/m2, and the total solar panel surface areas were 1 and 17 m2, respectively. Both wind-electric systems powered three-phase 230 V a-c induction motors with centrifugal pumps. The smaller of the solar-PV systems powered a d-c motor with a diaphragm pump, and the larger one powered a single phase 230 V a-c induction motor with a centrifugal pump. Only a well pumping depth of 30 m was evaluated for both wind-electric and solar-PV water pumping systems. The 0.1 kW and the 0.9 kW solar water pumping systems can provide enough water for 25 and 75 cattle, respectively, if the incident solar radiation is similar to that of Bushland, TX. The 1.0 kW and 1.5 kW wind-electric water pumping systems can provide enough water for 300 and 400 cattle, respectively, if the wind regime is similar to that of Bushland, TX.
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Dibaj, Mahdieh, Akbar A. Javadi, Mohammad Akrami, et al. "Modelling seawater intrusion in the Pingtung coastal aquifer in Taiwan, under the influence of sea-level rise and changing abstraction regime." Hydrogeology Journal 28, no. 6 (2020): 2085–103. http://dx.doi.org/10.1007/s10040-020-02172-4.
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Abstract A three-dimensional variable-density finite element model was developed to study the combined effects of overabstraction and seawater intrusion in the Pingtung Plain coastal aquifer system in Taiwan. The model was generated in different layers to represent the three aquifers and two aquitards. Twenty-five multilayer pumping wells were assigned to abstract the groundwater, in addition to 95 observation wells to monitor the groundwater level. The analysis was carried out for a period of 8 years (2008–2015 inclusive). Hydraulic head, soil permeability, and precipitation were assigned as input data together with the pumping records in different layers of the aquifer. The developed numerical model was calibrated against the observed head archives and the calibrated model was used to predict the inland encroachment of seawater in different layers of the aquifer. The effects of pumping rate, sea-level rise, and relocation of wells on seawater intrusion were examined. The results show that all layers of the aquifer system are affected by seawater intrusion; however, the lengths of inland encroachment in the top and bottom aquifers are greater compared with the middle layer. This is the first large-scale finite-element model of the Pingtung Plain, which can be used by decision-makers for sustainable management of groundwater resources and cognizance of seawater intrusion in coastal aquifers.
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Huang, Sun Wei, Yue Yu Wang, and Jin Shi. "Research on the Three-Level Inverter Midpoint Potential Algorithm Based on the Charge Balance Theory." Advanced Materials Research 986-987 (July 2014): 1850–53. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.1850.
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In order to achieve high voltage, high-power,two-level inverter need to switch in series which results switch static, dynamic-pressure problems. Three-level inverter solve this problem for its circuit, but this circuit has the midpoint potential imbalances of the DC side, we propose to charge balance theory based on the three-level inverter midpoint potential algorithm to solve the problem, build simulation model to validate the algorithm on the midpoint potential in MATLAB.
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Lin, Zhe, Jiahao Chen, Yusong Zhang, Jianguo Shen, Sheng Li, and Thomas F. George. "Charge Accumulation of Amplified Spontaneous Emission in a Conjugated Polymer Chain and Its Dynamical Phonon Spectra." Molecules 25, no. 13 (2020): 3003. http://dx.doi.org/10.3390/molecules25133003.
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In this article, the detailed photoexcitation dynamics which combines nonadiabatic molecular dynamics with electronic transitions shows the occurrence of amplified spontaneous emission (ASE) in conjugated polymers, accompanied by spontaneous electric polarization. The elaborate molecular dynamic process of ultrafast photoexcitation can be described as follows: Continuous external optical pumping (laser of 70 µJ/cm2) not only triggers the appearance of an instantaneous four-level electronic structure but causes population inversion for ASE as well. At the same time, the phonon spectrum of the conjugated polymer changes, and five local infrared lattice vibrational modes form at the two ends, which break the original symmetry in the system and leads to charge accumulation at the ends of the polymer chain without an external electric field. This novel phenomenon gives a brand-new avenue to explain how the lattice vibrations play a role in the evolution of the stimulated emission, which leads to an ultrafast effect in solid conjugated polymers.
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Mahmoud Ismail, Mohamed, and Ahmed Fahmy Bendary. "FOPID Controller Based AC Pump Supplied from PV Standalone Source Tuned using Fuzzy Logic Type 2." Indonesian Journal of Electrical Engineering and Computer Science 4, no. 1 (2016): 10. http://dx.doi.org/10.11591/ijeecs.v4.i1.pp10-19.
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This paper presents 500 KW three phase standalone photovoltaic systems supplying pumping station consist of four pumps 80 KW rating. The system utilizes a two stage energy conversion power conditioning unit topology composed of a DC-DC boost converter and three level-three phase voltage source inverter (VSI). The Boost converter in this paper is designed to operate in continuous mode and controlled for maximum power point tracking (MPPT). In this paper, the performance of the pumps is improved by adapting the controller of MPPT using different techniques. The system is modeled and studied using MATLAB/Simulink.
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Zhao, Tian, Di Liu, Ke-Lun He, Xi Chen, and Qun Chen. "An Integrated Three-Level Synergetic and Reliable Optimization Method Considering Heat Transfer Process, Component, and System." Energies 13, no. 16 (2020): 4112. http://dx.doi.org/10.3390/en13164112.
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Optimization of heat transfer systems (HTSs) benefits energy efficiency. However, current optimization studies mainly focus on the improvement of system design, component design, and local process intensification separately, which may miss the optimal results and lack reliability. This work proposes a synergetic optimization method integrating levels of the local process, component to system, which could guarantee the reliability of results. The system-level optimization employs the heat current method and hydraulic analysis, the component level optimization adopts heuristic optimization algorithm, and the process level optimization applies the field synergy principle. The introduction of numerical simulation and iteration provides the self-consistency and credibility of results. Optimization results of a multi-loop heat transfer system present that the proposed method can save 16.3% pumping power consumption comparing to results only considering system and process level optimization. Moreover, the optimal parameters of component originate from the trade-off relation between two competing mechanisms of performance enhancement, i.e., the mass flow rate increase and shape variation. Finally, the proposed method is not limited to heat transfer systems but also applicable to other thermal systems.
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Smerdon, B. D., C. A. Mendoza, and A. M. McCann. "Quantitative investigations of the hydraulic connection between a large reservoir and a buried valley aquifer in southern Alberta." Canadian Geotechnical Journal 42, no. 5 (2005): 1461–73. http://dx.doi.org/10.1139/t05-065.
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Quantitative investigations, including two aquifer tests and development of a three-dimensional (3D) groundwater flow model, were required to determine the hydraulic connection between an irrigation reservoir and a buried valley aquifer in southern Alberta. Evidence of seepage was detected in the buried valley aquifer 10 km east of the Pine Coulee reservoir at the onset of filling in 1999, when the reservoir level exceeded an elevation of 1035 m above sea level (a.s.l.). Concern for an increase in the local water table and the creation of artesian conditions in the aquifer prompted this study to determine the approximate location of a seepage window that appeared to be connecting the reservoir and aquifer. Observations of hydraulic head in the aquifer during the pumping tests revealed a barrier boundary when the reservoir level was at an elevation of 1035 m a.s.l. and a recharge boundary condition when the elevation exceeded 1039 m a.s.l. These data were used to calibrate a 3D groundwater flow model, which was needed to determine the hydraulic properties and approximate location of the leakage zone. The quantitative investigation showed that seepage likely occurred through the sideslopes of the flooded coulee, rather than through the low-permeability coulee floor sediments or the embankment dam. Further simulations illustrated the expected seepage rates at various reservoir supply levels and the pumping rates required for relief wells installed in the buried valley aquifer to maintain historic aquifer hydraulic head. A brief postanalysis indicated that the forecasted pumping rates were only 15% lower than have been required to maintain preconstruction water levels in the buried valley aquifer.Key words: dams, seepage analysis, groundwater modelling, buried valley aquifer, pumping test.
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Hamedi, Hamid R., Emmanuel Paspalakis, and Vassilios Yannopapas. "Effective Control of the Optical Bistability of a Three-Level Quantum Emitter near a Nanostructured Plasmonic Metasurface." Photonics 8, no. 7 (2021): 285. http://dx.doi.org/10.3390/photonics8070285.
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We study, theoretically, the phenomena optical bistability and multistability of a hybrid quantum-plasmonic system immersed within an optical ring cavity. The hybrid quantum-plasmonic system consists of a three-level V-type quantum emitter and a two-dimensional plasmonic metasurface of gold nanoshells. The quantum emitter and the plasmonic metasurface are placed in close proximity to each other so that a strong quantum interference of spontaneous emission occurs, which enables the strong modification of optical-bistability/ multistability hysteresis curves. Along with this, the strong interaction between the emitter and the plasmonic metasurface allows for active control of the corresponding bistable threshold intensity. Furthermore, we show that by varying the metasurface-emitter separation, a transition from bistability to multistability of the hybrid system is observed. Lastly, by introducing an additional incoherent pumping in the system, we have the emergence of phenomena, such as probe absorption and gain, with or without population inversion. The results may find technological application in on-chip nanoscale photonic devices, optoelectronics and solid-state quantum information science.
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Tang, Hong Wei, Xi Kun Chen, and Yan Xia Gao. "Study of Topology and Control Strategy of the Bidirectional Energy Storage Converter Based on Three-Level." Applied Mechanics and Materials 397-400 (September 2013): 1169–73. http://dx.doi.org/10.4028/www.scientific.net/amm.397-400.1169.
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To adapt to the requirements of the charging and discharging of the lithium battery, the paper presents a three-level based bidirectional energy storage converter topology.It has strong adaptability and can manage the charge and discharge of multi-series and parallel battery module. The mathematical model of the converter is analyzed, and the two operation modes of the converter control strategy are studied; Analysis the feed-forward decoupling control of three-level rectifier, and the variable scale factor is used to control midpoint potential. The simulation results demonstrate the feasibility of the design.
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Amarnath, Gaini, and Trupti Ranjan Lenka. "Analytical Model Development for Unified 2D Electron Gas Sheet Charge Density of AlInN/GaN MOSHEMT." International Journal of Electronics and Telecommunications 63, no. 4 (2017): 363–68. http://dx.doi.org/10.1515/eletel-2017-0049.
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Abstract We have developed a unified analytical model for computation of 2D electron gas sheet charge density in AlInN/GaN metal-oxide-semiconductor high electron mobility transistor device structure. This model has been developed by incorporating the variation in lowest three energy sub-bands and Fermi level energy in the quantum-well with respect to gate voltage. We noticed that the dependency of lowest sub-band energy with Fermi energy having two fields, which are the lowest sub-band energy is greater and lesser than the Fermi level energy. According to these two fields, we have developed the fermi energy and sheet charge density expressions in each field. By combining each field of the models, developed a unified 2D electron gas sheet charge density model. The Fermi level and sheet charge density are interdependent in the model development. The developed model results are compared with TCAD simulation results and obtain a good consistency between them. This model is fitted to other metal-oxide-semiconductor high electron mobility transistor devices also with modifications in related physical values.
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Mahmoud Ismail, Mohamed. "Daily Constant PV Output Power Supplying AC pumps using Batteries." Indonesian Journal of Electrical Engineering and Computer Science 2, no. 2 (2016): 275. http://dx.doi.org/10.11591/ijeecs.v2.i2.pp275-284.
Full textAbstract:
This paper presents 200 KW three phase standalone photovoltaic systems supplying pumping station consist of four pumps 40 KW rating. The system utilizes a two stage energy conversion power conditioning unit topology composed of a DC-DC boost converter and three level-three phase voltage source inverter (VSI). The Boost converter in this paper is designed to operate in continuous mode and controlled for maximum power point tracking (MPPT). The fluctuating output power of the PV array system during the day is the commonly problem in the power system. In this paper a nickel-Cadmium battery will be used to maintain the output power generated from the PV array supplying the pumps to be constant all the day under different operating conditions. The system is modeled and studied using MATLAB/Simulink
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Mendonça, Anny Key de Souza, and Antonio Cezar Bornia. "Electric power generation in wind farms with pumping kites: levelized cost of energy and sensitivity analysis." Research, Society and Development 9, no. 7 (2020): e666974528. http://dx.doi.org/10.33448/rsd-v9i7.4528.
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This research aims to analyze the levelized level energy cost of energy (LCOE) of wind farms with tethered airfoils. For this, it was considering the technical characteristics of the system, the location of operation, the necessary investments and the characteristics of the Brazilian market, to analyze the levelized cost of energy of three wind farm scenarios: Classic wind farm, Wind farm with tethered airfoils operating in Pumping Kite mode and a hybrid park with the two park configurations studied. The research makes use of the LCOE method. The results indicate that the technology with wired airfoils requires less investment and that wind farms with this technology can generate more energy than a classic wind farm of the same nominal power, since the wired airfoils can exploit high altitude winds, where they are more frequent and strong. The results also indicate that wind farms with wired airfoils are not only economically viable, but produce energy at a level cost, well below the values currently practiced for the sale of energy in the domestic market.
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Shirazi, Najmeh Cheraghi, Abumoslem Jannesari, and Pooya Torkzadeh. "Fast-Transient-Response Low-Voltage Integrated, Interleaved DC–DC Converter for Implantable Devices." Journal of Circuits, Systems and Computers 29, no. 01 (2019): 2050013. http://dx.doi.org/10.1142/s0218126620500139.
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A new self-start-up switched-capacitor charge pump is proposed for low-power, low-voltage and battery-less implantable applications. To minimize output voltage ripple and improve transient response, interleaving regulation technique is applied to a multi-stage Cross-Coupled Charge Pump (CCCP) circuit. It splits the power flow in a time-sequenced manner. Three cases of study are designed and investigated with body-biasing technique by auxiliary transistors: Four-stage Two-Branch CCCP (TBCCCP), the two-cell four-stage Interleaved Two-Branch CCCP (ITBCCCP2) and four-cell four-stage Interleaved Two-Branch CCCP (ITBCCCP4). Multi-phase nonoverlap clock generator circuit with body-biasing technique is also proposed which can operate at voltages as low as CCCP circuits. The proposed circuits are designed with input voltage as low as 300 to 400[Formula: see text]mV and 20[Formula: see text]MHz clock frequency for 1[Formula: see text]pF load capacitance. Among the three designs, ITBCCCP4 has the lowest ramp-up time (41.6% faster), output voltage ripple (29% less) and power consumption (19% less). The Figure-Of-Merit (FOM) of ITBCCCP4 is the highest value among two others. For 400[Formula: see text]mV input voltage, ITBCCCP4 has a 98.3% pumping efficiency within 11.6[Formula: see text][Formula: see text]s, while having a maximum voltage ripple of 0.1% and a power consumption as low as 2.7[Formula: see text]nW. The FOM is 0.66 for this circuit. The designed circuits are implemented in 180-nm standard CMOS technology with an effective chip area of [Formula: see text][Formula: see text][Formula: see text]m for TBCCCP, [Formula: see text][Formula: see text][Formula: see text]m for ITBCCCP2 and [Formula: see text][Formula: see text][Formula: see text]m for ITBCCCP4.
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Tal, Adi, Yishai Weinstein, Stuart Wollman, Mark Goldman, and Yoseph Yechieli. "The Interrelations between a Multi-Layered Coastal Aquifer, a Surface Reservoir (Fish Ponds), and the Sea." Water 10, no. 10 (2018): 1426. http://dx.doi.org/10.3390/w10101426.
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This research examines the interrelations in a complex hydrogeological system, consisting of a multi-layered coastal aquifer, the sea, and a surface reservoir (fish ponds) and the importance of the specific connection between the aquifer and the sea. The paper combines offshore geophysical surveys (CHIRP) and on land TDEM (Time Domain Electro Magnetic), together with hydrological measurements and numerical simulation. The Quaternary aquifer at the southern Carmel plain is sub-divided into three units, a sandy phreatic unit, and two calcareous sandstone (‘Kurkar’) confined units. The salinity in the different units is affected by their connection with the sea. We show that differences in the seaward extent of its clayey roof, as illustrated in the CHIRP survey, result in a varying extent of seawater intrusion due to pumping from the confined units. FEFLOW simulations indicate that the FSI (Fresh Saline water Interface) reached the coastline just a few years after pumping has begun, where the roof terminates ~100 m from shore, while no seawater intrusion occurred in an area where the roof is continuous farther offshore. This was found to be consistent with borehole observations and TDEM data from our study sites. The water level in the coastal aquifer was generally stable with surprisingly no indication for significant seawater intrusion although the aquifer is extensively pumped very close to shore. This is explained by contribution from the underlying Late Cretaceous aquifer, which increased with the pumping rate, as is also indicated by the numerical simulations.
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Yao, Fang Fang, Xiao Jing Zhang, Zhi Qiang Gao, and Xiao Wei Liu. "Design of Charge Pump for Inertial Sensor Drive Circuit." Key Engineering Materials 609-610 (April 2014): 942–51. http://dx.doi.org/10.4028/www.scientific.net/kem.609-610.942.
Full textAbstract:
A transistor-level circuit design of charge pump is introduced to drive the inertial device. The design is made of several big modules, including main charge pump module, band gap reference module, comparator module, oscillating module, control module, temperature protection module. A three-stage charge pump is applied to achieve 5 V to 18 V DC/DC conversion, and each stage uses the cross coupled charge pump circuit, taking body effect, threshold voltage drop and efficiency into account. Considering efficiency and power consumption, the band gap reference module adopts a self-biased op amp. To make the comparator transient response fast, the op amp cascades two inverters. The temperature protection module sets a maximum temperature to protect the charge pump. The control module is composed of a data selector, a two-phase non-overlap clock circuit and a frequency divider to optimize clock signal. Then simulations are given and the charge pump is analyzed, finally the efficiency of charge pump is calculated. Designed in CSMC 0.5um process, the charge pump has an efficiency of 87.63 percent, a 19.85V output voltage, a 100 mA output current, and 6.05mV ripple.
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Liu, Mei, Ying Shi, Guangping Zhang, et al. "Surface-Enhanced Raman Spectroscopy of Two-Dimensional Tin Diselenide Nanoplates." Applied Spectroscopy 72, no. 11 (2018): 1613–20. http://dx.doi.org/10.1177/0003702818794685.
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Surface-enhanced Raman spectroscopy (SERS) is a powerful spectroscopy technique to detect and characterize molecules at a very low concentration level. The two-dimensional (2D) semi-conductor layered material, tin diselenide (SnSe2), is used as a new substrate for enhancing the Raman signals of adsorbed molecules. Three kinds of molecules—Rhodamine 6G (R6G), crystal violet (CV), and methylene blue (MB)—are used as probe molecules to evaluate the SERS performance of SnSe2. The Raman signals of different molecules can be enhanced by SnSe2 nanoplates (NPs). The distinguishable Raman signal of R6G molecules can be obtained for adsorbent concentrations as low as 10−17 mol/L. Based on a detailed analysis of the bandgap structure and opto-electrical properties of SnSe2 NPs, we discuss the process of charge transfer and the Raman enhancement mechanism of SnSe2 NP. The high Raman sensitivity of SnSe2 NPs is related to the charge transfer between molecules and SnSe2, 2D layered structure, and indirect bandgap of few-layered SnSe2. The research results will help to expand the application of SnSe2 in microanalysis, improve the measurement accuracy of SERS, and possibly find use in optoelectronic device integration.
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Dang, V. K., C. Doubre, C. Weber, N. Gourmelen, and F. Masson. "Recent land subsidence caused by the rapid urban development in the Hanoi region (Vietnam) using ALOS InSAR data." Natural Hazards and Earth System Sciences 14, no. 3 (2014): 657–74. http://dx.doi.org/10.5194/nhess-14-657-2014.
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Abstract. Since the 1990s the land subsidence due to the rapid urbanization has been considered a severely destructive hazard in the center of Hanoi City. Although previous studies and measurements have quantified the subsiding deformation in Hanoi center, no data exist for the newly established districts in the south and the west, where construction development has been most significant and where groundwater pumping has been very intensive over the last decade. With a multi-temporal InSAR approach, we quantify the spatial distribution of the land subsidence in the entire Hanoi urban region using ALOS images over the 2007–2011 period. The map of the mean subsidence velocity reveals that the northern bank of the Red River appears stable, whereas some areas in southern bank are subsiding with a mean vertical rate up to 68.0 mm yr−1, especially within the three new urban districts of Hoang Mai, Ha Dong – Thanh Xuan and Hoai Duc – Tu Liem. We interpret the spatial distribution of the surface deformation as the combination of the nature of the unsaturated layer, the lowering of groundwater in the aquifers due to pumping withdrawal capacity, the increase of built-up surfaces and the type of building foundation. The piezometric level in Qp aquifer lowers particularly after 2008, whereas the groundwater level in Qh aquifer remains steady, even if it loses its seasonal fluctuation in urban areas and drawdowns in neighboring water production plants. The time evolution deduced from the InSAR time series is consistent with previous leveling data and shows that the lowering rate of the surface slightly decreases till 2008. The analysis of groundwater levels in instrumented wells shows a correlation between the behavior of groundwater with the urban development and the acceleration of groundwater withdrawal. Also, the time variations suggest that the deformation became non-stationary, with upward and downward transient displacements related to the charge and discharge of the aquifers.
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Ortiz-Soto, Elliott A., George A. Lavoie, Margaret S. Wooldridge, and Dennis N. Assanis. "Thermodynamic efficiency assessment of gasoline spark ignition and compression ignition operating strategies using a new multi-mode combustion model for engine system simulations." International Journal of Engine Research 20, no. 3 (2018): 304–26. http://dx.doi.org/10.1177/1468087417752195.
Full textAbstract:
Advanced combustion strategies for gasoline engines employing highly dilute and low-temperature combustion modes, such as homogeneous charge compression ignition and spark-assisted compression ignition, promise significant improvements in efficiency and emissions. This article presents a novel, reduced-order, physics-based model to capture advanced multi-mode combustion involving spark ignition, homogeneous charge compression ignition and spark-assisted compression ignition operating strategies. The purpose of such a model, which until now was unavailable, was to enhance existing capabilities of engine system simulations and facilitate large-scale parametric studies related to these advanced combustion modes. The model assumes two distinct thermodynamic zones divided by an infinitely thin flame interface, where turbulent flame propagation is captured using a new zero-dimensional formulation of the coherent flame model, and end-gas auto-ignition is simulated using a hybrid approach employing chemical kinetics and a semi-empirical burn rate model. The integrated model was calibrated using three distinct experimental data sets for spark ignition, homogeneous charge compression ignition and spark-assisted compression ignition combustion. The results demonstrated overall good trend-wise agreement with the experimental data, including the ability to replicate heat release characteristics related to flame propagation and auto-ignition during spark-assisted compression ignition combustion. The calibrated model was assessed using a large parametric study, where the predicted homogeneous charge compression ignition and spark-assisted compression ignition operating regions at naturally aspirated conditions were representative of those determined during engine testing. Practical advanced combustion strategies were assessed relative to idealized engine simulations, which showed that efficiency improvements up to 30% compared with conventional spark-ignition operation are possible. The study revealed that poor combustion efficiency and pumping work are the primary mechanisms for efficiency losses for the advanced combustion strategies evaluated.
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Hall, B. V., R. T. Sang, M. Shurgalin, W. R. MacGillivray, M. C. Standage, and P. M. Farrell. "Electron superelastic scattering from states of atomic sodium and rubidium." Canadian Journal of Physics 74, no. 11-12 (1996): 977–83. http://dx.doi.org/10.1139/p96-817.
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This paper reports on the extension of the electron superelastic scattering technique to three new situations. The first considers scattering from the 32P3/2 level of Na that has been excited by two laser modes tuned, respectively, to the transitions from the two hyperfine states of the 32S1/2 ground level. Both coherent and noncoherent modes are treated in a full quantum electrodynamic model of the laser excitation. Under certain conditions, the time-averaged probability of finding an atom in the 32P3/2 level exceeds 0.5. The second situation is electron superelastic scattering from the 32D5/2 level of Na that has been resonantly excited from the ground level via a resonant intermediate level. With the first observation of superelastically scattered electrons from this higher lying level recently recorded, this paper considers the extension of the quantum electrodynamics (QED) model to describe the optical excitation process. Application of superelastic scattering to the 52S1/2–52P3/2 transition of Rb is the third situation considered. The superelastic scattering formalism is extended to allow for a nonzero spin flip cross section for this transition. The resulting optical pumping terms are calculated using the QED model and the method of their determination for the superelastic scattering experiment described. The experimental design necessary to measure all of the collision parameters for this transition is discussed.
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FLORES, F. "ALKALI-ATOM ADSORPTION ON SEMICONDUCTOR SURFACES: METALLIZATION AND SCHOTTKY-BARRIER FORMATION." Surface Review and Letters 02, no. 04 (1995): 513–37. http://dx.doi.org/10.1142/s0218625x95000480.
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Alkali metals deposited on weakly ionic semiconductors are neither reactive nor form large three-dimensional islands, offering an ideal system in which Schottky junctions can be analyzed. In this paper, the alkali-metal-semiconductor interface is reviewed with a special emphasis on the formation of the Schottky barrier. Two regimes are clearly differentiated for the deposition of AMs on a semiconductor: in the high-coverage limit the Schottky barrier is shown to depend, for not very defective interfaces, on the semiconductor charge neutrality level. For low coverages, different one- and two-dimensional structures appear on the semiconductor surface presenting an insulating behavior. For depositions around a metal monolayer, a Mott metal-insulator transition appears; then, the interface Fermi energy is pinned by the metallic density of states at the position determined by the semiconductor charge neutrality level. This situation defines the Schottky barrier height of a thick-metal overlayer.
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KUMAR, GIRISH, VIPUL JAIN, and O. P. GANDHI. "RELIABILITY AND AVAILABILITY ANALYSIS OF MECHANICAL SYSTEMS USING STOCHASTIC PETRI NET MODELING BASED ON DECOMPOSITION APPROACH." International Journal of Reliability, Quality and Safety Engineering 19, no. 01 (2012): 1250005. http://dx.doi.org/10.1142/s0218539312500052.
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Reliability and availability assessment of a complex system in a single model, considering binary states of individual components, using Markov technique is difficult due to state space explosion problem. Inclusion of various types of dependencies in the model further aggravates it. To overcome this, Stochastic Petri net (SPN) modeling based on decomposition is proposed for reliability and availability assessment of mechanical systems. The decomposition is based on three aspects of the system: Hierarchical level, basic structure and dependency. The model is demonstrated at three hierarchical levels. Individual component (level '3') SPN model is developed assuming Weibull failure distribution, while the individual subsystem (level '2') SPN model is developed considering the arrangement of components within the subsystem. The individual model at level '2' is reduced to an equivalent single net model and its equivalent transition rate is derived from its basic structure assuming the independence of components. This along with the dependencies (e.g. repair, standby redundancy) are included in the system model (level '1'). The repair distribution in this model is assumed exponential. Reachable markings are generated for the system model to obtain the reduced state space of Semi-Markov model for assessment of reliability and availability of the system. The steps of the proposed methodology are suggested and these are illustrated for a pumping system, with two pumps; one in standby.
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Brandt, Justin T., Michelle Sneed, and Wesley R. Danskin. "Detection and measurement of land subsidence and uplift using interferometric synthetic aperture radar, San Diego, California, USA, 2016–2018." Proceedings of the International Association of Hydrological Sciences 382 (April 22, 2020): 45–49. http://dx.doi.org/10.5194/piahs-382-45-2020.
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Abstract. Land subsidence associated with groundwater-level declines is stipulated as an “undesirable effect” in California's Sustainable Groundwater Management Act (SGMA), and has been identified as a potential issue in San Diego, California, USA. The United States Geological Survey (USGS), the Sweetwater Authority, and the City of San Diego, undertook a cooperative study to better understand the hydromechanical response of the coastal aquifer system using Interferometric Synthetic Aperture Radar (InSAR) techniques. Three periods of interest were analyzed for this study that correspond to the periods before and after two substantial changes were made to the location and volume of pumpage: (1) April–August 2016 when groundwater levels and land surface elevation were relatively stable during normal pumping, (2) September 2016–May 2017 when groundwater levels recovered and the land surface uplifted during a period of substantially reduced pumping, (3) June 2017–October 2018 when groundwater levels declined and land subsidence occurred when pumpage resumed and expanded to new wells. Spatial and temporal characterization of the hydromechanical response to changes in pumpage is important for managing land subsidence. Further study using InSAR techniques, especially when combined with ground-based geodetic and monitoring-well networks, will provide water managers information to help effectively manage groundwater resources as stipulated in the SGMA.
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Hussan, Md Reyaz, Adil Sarwar, Irfan Khan, Mohd Tariq, Mohammad Tayyab, and Waleed Alhosaini. "An Eleven-Level Switched-Capacitor Inverter with Boosting Capability." Electronics 10, no. 18 (2021): 2262. http://dx.doi.org/10.3390/electronics10182262.
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An 11-level switched-capacitor multilevel inverter (SCMLI) with 2.5 times boosting feature is presented in this paper. It can produce an 11-level output voltage waveform by utilizing 14 switches, 3 capacitors, 2 diodes, and 1 DC source. Only nine driver circuits are needed as the topology has three pairs of complementary switches and two bidirectional switches. It has inherent capacitor self-balancing property as the capacitors are connected across the DC voltage source during several states within a fundamental cycle to charge the capacitors to the input voltage. A detailed comparison shows the effectiveness of the proposed topology in terms of the number of switches, number of capacitors, number of sources, total standing voltage (TSV), efficiency, and boosting ability with the state-of-art recently proposed circuits. Subsequently, the performance of the proposed SCMLI is validated experimentally utilizing the nearest level control (NLC), a fundamental frequency-based switching technique.
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Long, Yu Qiao, Wei Li, Wen Xi Lu, and Ting Ting Cui. "Modeling the Recovery of the Spring Flow and Groundwater Level in a Depleted Karst Aquifer - A Case Study of the Jinci Spring." Applied Mechanics and Materials 448-453 (October 2013): 989–94. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.989.
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A reservoir model is developed to characterize the functioning of the karst aquifer of the Jinci Spring. It is based on the relationship of the groundwater storage deficit and the groundwater level. The relationship is derived from the monitoring data of the aquifer. The model is verified with the monitoring data (1981-2006) and is used to predict the recovery of the Jinci Spring flow and the groundwater level in the aquifer under three exploitation schemes with the future rainfall data provided by the National Climate Center (NCC). The results show that the Jinci Spring will flow out again before 2050 under Scheme I and II. The Xuan Spring will flow out earlier than the Jinci Spring. However, both of the two springs cannot spout under Scheme III. The model takes account of the artificial recharge, pumping and coal mine drainage, and can simulate the spring discharge, karst groundwater level and the storage deficit accurately at an annual time scale. The model is suitable for macroscopic groundwater management.
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Zichichi, Antonino. "The Gap and the origin of the fundamental forces." International Journal of Modern Physics A 31, no. 35 (2016): 1630060. http://dx.doi.org/10.1142/s0217751x1630060x.
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The energy level where the best values of the three fundamental gauge couplings [Formula: see text] converge is at least two orders of magnitude below the Planck energy level. The existence of this Gap could imply that the gravitational force ‘comes into being’ before QED, QFD and QCD. The most interesting consequence of the Gap would then be the existence of matter whose charge is only the gravitational charge. If this is so, events should be detected where only gravitational waves are produced. Primordial black holes (PBHs) would be produced much more frequently than the standard black holes (SBHs) since SBHs would be ‘derivative’ effects produced later, after matter made with protons, electrons, neutrons, and stars can exist. Collisions between PBHs generating only gravitational waves should be more frequent than SBHs collisions.
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Rozlan, Ainul Fauzeeha, Shukri Sulaiman, M. I. Mohamed-Ibrahim, and Isao Watanabe. "Electronic Structure of Muonated La2CuO4." Materials Science Forum 827 (August 2015): 240–42. http://dx.doi.org/10.4028/www.scientific.net/msf.827.240.
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We have performed First Principle computational studies utilizing Molecular-Orbital (MO) Cluster method to examine the electronic structure of muonated La2CuO4. Based on recent works, we investigated three suggested muon sites in La2CuO4. Two possible muon sites are located near the apical oxygen O(a), and the other one is near the planar oxygen O(p). The calculations were performed at the HF/Gen level of theory. The results of our investigation show that there is a very significant covalency effect between copper and oxygen. In the pure system, the effective charge on Cu is 0.77 while the charge on the oxygens is around –1.8. In the muonated system, the charge on Cu reduces to 0.58. The spin density at Cu is 0.78 in the pure system and becomes 0.70 when muon is added. As for the muon, the charge and spin density are +0.22 and –0.0026 respectively.