The STAR experiment provides measurements of single and double-spin asymmetries in longitudinally and transversely polarized
p
+
p
collisions at
s
= 200 and 510 GeV to deepen our understanding on the ...proton spin structure and dynamics of parton interactions over a wide range of collision energy, momentum and rapidity of the various produced probes. Polarized processes with
W
±
production allow us to study the spin-flavor structure of the proton. Recent results obtained by STAR on the double longitudinal asymmetry,
A
LL
, of pion and jet production at
s
= 200 and 510 GeV, the single longitudinal,
A
L
, and transverse,
A
N
, asymmetry of
W
±
production at
s
= 510 GeV are overviewed. STAR results on azimuthal single transverse asymmetry of pion in
p
↑
+ (
p
,
Au
) and jet + π
±
in
p
↑
+
p
collisions are discussed. The proposed Forward Calorimeter System (FCS) and Forward Tracking System (FTS) upgrades at STAR would significantly improve the capabilities of existing detectors for measurements of observables such as asymmetries of pion, jet, Drell-Yan pairs produced at forward rapidities.
The results of a fractal analysis of Monte Carlo AuAu events at the c.m. collision energy of
GeV on the basis of the method of the System of Equations of P-basic Coverage (SePaC) are presented. A ...MultiPhase Transport (AMPT) model is used to generate collision events. The transverse momentum
of negatively charged particles detected in the pseudorapidity range of
in events of different centrality between (0–5)
and (30–40)
is considered as the variable under study. Sets of random events and Monte Carlo fractals are compared. The difference in the behavior of the dependence of the fraction of events reconstructed as fractals on the parameters of the method for different types of data are demonstrated. Optimum values of the parameters for an analysis of AMPT AuAu events are found. It is indicated that the portion of Prtn events reconstructed as fractals depend on the centrality and multiplicity in AuAu and random events, respectively. Insignificant distinctions in the behavior of the distributions with respect to dimension
for different centrality classes are found. Two event classes differing in the shape of transverse-moment spectra are singled out among AMPT AuAu events.
Abstract Using a wind tunnel, a series of model finned flat tube copper radiators was studied. All geometrical parameters of the studied radiators were fixed except for the height of the fin, which ...was varied in the range from 5 to 20 mm. It was found that the global water-air heat transfer coefficient weakly depends on the water flow rate and significantly depends on the air flow rate. Correlations between the Nusselt and Reynolds numbers for fins with different heights are found. Based on the obtained correlations, a procedure for scaling the heat exchanger, verified experimentally, is proposed. The experiments performed demonstrate the efficiency and time-saving potential of the proposed method for choosing the optimal finned flat tube heat exchanger for adsorption heat conversion systems.
-Scaling of inclusive spectra as a manifestation of self-similarity and fractality of hadron interactions is illustrated. The scaling for negative particle production in
collisions from BES-I program ...at RHIC is demonstrated. The scaling variable
depends on the momentum fractions of the colliding objects carried by the interacting constituents, and on the momentum fractions of the fragmenting objects in the scattered and recoil directions carried by the inclusive particle and its counterpart, respectively. Structures of the colliding objects and fragmentation processes in final state are expressed by fractal dimensions. Medium produced in the collisions is described by a specific heat. The scaling function
reveals energy, angular, multiplicity, and flavor independence. It has a power behavior at high
(high
). Based on the entropy principle and
-scaling, energy loss as a function of the collision energy, centrality and transverse momentum of inclusive particle is estimated. New conservation law including fractal dimensions is found. Quantization of fractal dimensions is discussed.
•The criteria for optimal AdHex for air conditioning cycle were formulated.•AdHex should provide the maximal power per unit of its volume.•Heat removal should be balanced with heat generation due to ...adsorption.•Mathematical model of AdHex performance was proposed and experimentally verified.•The optimal geometry of AdHex for considered air conditioning cycle was suggested.
Adsorption heat transformation (AHT) makes it possible to accumulate and use renewable energy and waste heat. This emerging technology is based on the reversible adsorption-desorption of vapour by an adsorbent. One of the most crucial factors affecting the AHT efficiency is heat transfer in the system "adsorbent-heat exchanger"(AdHex), which depends on the AdHex geometrical parameters. For designing compact and efficient units, it is necessary to maximize the AHT useful power per AdHex unit volume. Therefore, the optimization of AdHex geometry is an essential and urgent task. In this purpose the intensity of heat transfer and heat generation inside the restricted volume of AdHex have to be properly balanced. The aim of this work is to find out the optimal geometry of AdHex for adsorption chilling application with use of “methanol-LiCl/SiO2” working pair. The procedure for defining the optimal AdHex geometry is based on finding the compromise between the volume of the adsorbent granules placed inside the AdHex and number of plate channels and fins. The results of calculations were experimentally verified.
Fuel rod assemblies with tight lattice bundles are considered promising for increasing the conversion rate and heat transfer in small modular reactors. The main feature of the flow in a tight lattice ...rod bundle is the formation of quasi-periodic large-scale velocity oscillations in the gap between fuel rods. These oscillations enhance mixing between the subchannels and significantly increase heat transfer between the fuel rods and the coolant. The large-scale oscillations are directly related to the pitch-to-diameter (P/D) ratio of the rod bundle and the Reynolds number. In this study, we experimentally investigate the unsteady flow structure in a gap between a flat wall and three rods with a relative pitch P/D = 1.077 using time-resolved particle image velocimetry (TR-PIV) technique. The obtained TR-PIV velocity vector fields were used to analyze flow characteristics, including two- and three-dimensional mean velocity, velocity fluctuations, and Reynolds stress profiles. We also examined the influence of the Reynolds number on flow oscillations in the gap. The spatial most energy-intensive flow modes were further analyzed using the proper orthogonal decomposition (POD) method. Our results indicate the presence of several traveling waves propagating along the flow. Modulation of flow oscillations in the gap was observed. These findings are consistent with those of other researchers.
Two-phase bubble flows have been used in many technological and energy processes as processing oil, chemical and nuclear reactors. This explains large interest to experimental and numerical studies ...of such flows last several decades. Exploiting of optical diagnostics for analysis of the bubble flows allows researchers obtaining of instantaneous velocity fields and gaseous phase distribution with the high spatial resolution non-intrusively. Behavior of light rays exhibits an intricate manner when they cross interphase boundaries of gaseous bubbles hence the identification of the bubbles images is a complicated problem. This work presents a method of bubbles images identification based on a modern technology of deep learning called convolutional neural networks (CNN). Neural networks are able to determine overlapping, blurred, and non-spherical bubble images. They can increase accuracy of the bubble image recognition, reduce the number of outliers, lower data processing time, and significantly decrease the number of settings for the identification in comparison with standard recognition methods developed before. In addition, usage of GPUs speeds up the learning process of CNN owning to the modern adaptive subgradient optimization techniques.
Monte Carlo (MC)
events at an energy of
= 200 GeV, obtained using the AMPT generator, MC fractals, and events with randomly distributed particles are analyzed by the
method. The dependence of the ...portion
of the events under study, defined as fractals, on the method parameter
is investigated. It has been established that the hypotheses of independent and dependent formation of fractals correspond to different regions of behavior of
for AMPT
events. The
method makes it possible to extract AMPT
events with equal fractal dimensions
at different levels. The distribution of events by
are different for used hypotheses. Events identified by the hypothesis of independent devision have a group of leading particles according to
,
and the remaining ones exhibit exponential behavior of the
spectrum. The use of background suppression criteria describing the statistical characteristics of structures at different levels showed that a significant part of the events identified by the independent devision hypothesis have the same structures and can be interpreted as fractals. Events reconstructed by the dependent devision hypothesis are suppressed.
The possibility of controlling the composition of lateral nanowires by the method of growth under quasi-equilibrium conditions in a quasi-closed volume from indium, phosphorus, and arsenic vapors ...with Au catalyst in the “vapor-liquid-solid” mechanism has been demonstrated for the first time. It has been experimentally shown that the additional presence of arsenic in the indium-phosphorus source leads to the coalescence of catalytic gold droplets at the initial stage of the growth, which determines the further morphology and growth kinetics of nanostructures. An additional formation of indium phosphide nanostructures with a composition different from that of the main nanowires was found. The results of the studies expand the possibilities of the developed method for obtaining lateral nanowires on gallium arsenide substrates.
Objectives Long-term durability after endovascular aortic repair is influenced by stent graft migration causing types I and III endoleaks. Flow induced displacement forces have been shown to have the ...potential to cause migration. In this study, the influence of the distal diameter of iliac limb stent grafts and the shape of graft curvature on flow induced displacement forces, were investigated. Methods In an experimental pulsatile flow model mimicking aortic conditions in vivo, flow induced displacement forces at the proximal and distal ends of iliac limb stent grafts were studied at different angles (0–90°) and perfusion pressures (145/80, 170/90, 195/100 mmHg). Bell-bottomed, tapered, and non-tapered stent grafts and also asymmetric stent graft curvatures at 90° bend were studied. Measurements of graft movement were performed at all studied angulations and graft shapes. Results For all stent graft diameters, flow induced displacement forces increased with higher pressure and increased stent graft angulation. Forces in the bell-bottom graft were considerably higher than in tapered and non-tapered grafts, with a markedly elevated peak force at the distal end (proximal end, 2.3 ± 0.06 N and distal end, 6.9 ± 0.05 N compared with 1.7 ± 0.08 N and 1.6 ± 0.08 N in non-tapered grafts; p < .001 both). Peak forces in tapered and non-tapered grafts were not significantly different between the proximal and distal end. In asymmetric stent graft curvatures, a significant increase in displacement forces was observed in the attachment zone that was closest to the stent graft bend. Graft movement increased with greater displacement forces. Conclusion Flow induced displacement forces in iliac limb stent grafts are significant and are influenced by distal stent graft diameter and the shape of the graft curvature. The displacement forces are particularly high at the large distal end of bell-bottom grafts. Wide iliac arteries treated with bell-bottom stent grafts may require more vigilant surveillance and improved stent graft fixation.
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