The increasing global demand for energy and environmental concerns have provoked a shift from exhaustible, fossil fuel based energy to renewable energy sources. It is clear that wind energy will play ...an important role in satisfying our current and future energy demands. In this paper, a horizontal configuration of a Savonius wind turbine is proposed to be mounted on the upstream edge of a building, in such a way that its low performance is improved by taking advantage of the flow acceleration generated by the edge of the building. The importance of integrated simulations which include both the building and the turbine is shown and it is also demonstrated that the individual calculations of the flow around the building and the turbine individually cannot be superposed. Following the validation of our methodology with experimental data, we calculate the performance of the Savonius wind turbines placed in the vicinity of the edge of the building top. The position, blade number, and circumferential length are then investigated when the turbine is mounted on a building. The objective is to better understand wind turbine behavior for low speed urban environments. The flow fields of conventional Savonius and cup type turbines are solved using Computational Fluid Dynamics (CFD) in 3D domains. The optimal configuration shows an improvement in the power coefficient from 0.043 to 0.24, representing an improvement of 450%. The improvement also demonstrates that although cup type blades show very poor performance in free stream flow, they perform well in the right environment.
•Validation of Power Coefficient calculation from CFD for a Savonius turbine.•Analysis of the flow around a building mounted Savonius turbine.•Demonstration that Savonius turbines are inefficient when installed on buildings.•Developed of a drag based turbine that works in synergy with the building aerodynamics.
A
bstract
Using a total of 5
.
25 fb
−
1
of
e
+
e
−
collision data with center-of-mass energies from 4.236 to 4.600 GeV, we report the first observation of the process
e
+
e
−
→ ηψ
(2
S
) with a ...statistical significance of 4.9 standard deviations. The data sets were collected by the BESIII detector operating at the BEPCII storage ring. We measure the yield of events integrated over center-of-mass energies and also present the energy dependence of the measured cross section.
The article analyzes the efficiency of geothermal energy extraction method. Different regions of the Russian Federation were analyzed. Available geothermal energy extraction technologies using ...nomograms were analyzed. The nomograms describe the dynamics of outlet changes in temperatures and the amount of energy produced at various coefficients of thermal conductivity and heat capacity of rocks. The nomograms used for selection of suitable geothermal energy production technologies depending on geological and physical conditions were developed. Based on geological and physical characteristics of the bottomhole formation zone, such well parameters as the radii of the casing and the tubing and coolant velocity, outlet temperatures and thermal capacity of the well were calculated. The more efficient technology was selected.
A
bstract
Using 10
.
1
×
10
9
J/ψ
events produced by the Beijing Electron Positron Collider (BEPCII) at a center-of-mass energy
s
= 3
.
097 GeV and collected with the BESIII detector, we present a ...search for the rare semi-leptonic decay
J/ψ → D
−
e
+
ν
e
+ c.c. No excess of signal above background is observed, and an upper limit on the branching fraction ℬ(
J
/
ψ
→
D
−
e
+
ν
e
+
c
.
c
.) < 7.1 × 10
−8
is obtained at 90% confidence level. This is an improvement of more than two orders of magnitude over the previous best limit.
The mathematical model of volcanic treatment by means of conductive heat transfer from the well surrounding rocks has been suggested. We have shown that one of the ways of producing geothermal energy ...is to heat liquid in the double-tube monobore well. Water is pumped to the annulus between pump-compressor pipe (PCP) and casing pipe. Flowing down to the bottom hole, the liquid is heated up from a casing wall through convective and conductive thermal conductivity which adjoins surrounding rocks. The caloric goes to surrounding rocks from the earth crust interior. The heat flow is at an average equal to 50 MW/sq.m, it can differ depending on the region. The heated to the bottomhole water is lifted back to a surface through the PCP. To minimize heat wastes when lifting, PSP should be made of heat-insulating material. We suggest a multifaceted approach, combining the disposal of low-temperature geothermal energy which contained in the extracted product by means of thermopiles with utilization of the hydrokinetic energy, flood water through the system of formation-pressure maintenance by means of the hydroelectric turbine.
The article describes the innovative approach when predicting the resource potential efficiency of petrothermal energy. Various geothermal gradients representative of Bashkortostan and Tatarstan ...republics regions were considered. With the help of nomograms, the authors analysed fluid temperature dependency graphs at the outlet and the thermal power versus fluid velocity along the wellbore. From the family of graphs plotted by us, velocities corresponding to specific temperature were found. Then, according to thermal power versus velocity curve, power levels corresponding to these velocities relative to the selected fluid temperature were found. On the basis of two dependencies obtained, nomograms were plotted. The result of determining the petrothermal energy production efficiency is a family of isocline lines that enables one to select the optimum temperature and injection rate to obtain the required amount of heat for a particular depth and geothermal gradient.
The electromagnetic form factors (EMFFs) of the nucleon represent the simplest structure observables and serve as a testing ground for our understanding of the strong interaction. Using 669 pb−1 of ...data collected for a momentum transfer q2 (= −Q2) between 4.0 and 9.5 GeV2, the BESIII experiment obtained the most precise results on the nucleon magnetic form factor GM (the EMFF ratio Rem) up to date, with a relative precision of 1.8% (3.4%) for the proton and preliminary results with 8.9% (28%) for the neutron. An interesting oscillating behavior has been observed in the effective FF for both proton and neutron after the subtraction of the dipole-like parameterization, with an almost orthogonal phase difference between proton and neutron, indicating an unknown intrinsic dynamic hidden in the nucleon structure.
We report a study of the processes of e^{+}e^{-}→K^{+}D_{s}^{-}D^{*0} and K^{+}D_{s}^{*-}D^{0} based on e^{+}e^{-} annihilation samples collected with the BESIII detector operating at BEPCII at five ...center-of-mass energies ranging from 4.628 to 4.698 GeV with a total integrated luminosity of 3.7 fb^{-1}. An excess of events over the known contributions of the conventional charmed mesons is observed near the D_{s}^{-}D^{*0} and D_{s}^{*-}D^{0} mass thresholds in the K^{+} recoil-mass spectrum for events collected at sqrts=4.681 GeV. The structure matches a mass-dependent-width Breit-Wigner line shape, whose pole mass and width are determined as (3982.5_{-2.6}^{+1.8}±2.1) MeV/c^{2} and (12.8_{-4.4}^{+5.3}±3.0) MeV, respectively. The first uncertainties are statistical and the second are systematic. The significance of the resonance hypothesis is estimated to be 5.3 σ over the contributions only from the conventional charmed mesons. This is the first candidate for a charged hidden-charm tetraquark with strangeness, decaying into D_{s}^{-}D^{*0} and D_{s}^{*-}D^{0}. However, the properties of the excess need further exploration with more statistics.
Abstract
The article describes a thermal vacuum bench for studying the thermal modes of photodetectors. The bench allows simulating various thermal impacts on photodetectors in a wide range of ...temperatures.
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