Transfer Distribution Research Articles

High‐Lying Triplet Excitons Utilization of Silole Derivatives Enables their Efficiency Breakthrough in OLEDs

AbstractSiloles are routinely studied in the application of organic light‐emitting diodes (OLEDs) due to their high performances of solid‐state fluorescence property and carrier mobility. The structures of siloles used in electroluminescence device reported so far can only utilize singlet excitons, limiting the device efficiency and commercialization. Seeking to build appliable molecular structures to achieve triplet excitons utilization in silole‐core emitters, two derivatives are designed, Silole‐1DPA‐TRZ and Silole‐1Cz‐TRZ, in which electron acceptor of triazine (TRZ) together with electron donors of diphenylamine (DPA) and carbazole (Cz) modified at 1‐position of silole unit form silole‐D‐A structures. This special molecular design, for the first time, enables triplet excitons harvest via high‐lying reverse intersystem crossing (hRISC) process in silole derivatives with hybridized local and charge‐transfer (HLCT) characteristics. Experimental and theoretical studies show that relative to a stronger charge transfer state of Silole‐1Cz‐TRZ, a more equal local excitation/charge transfer distribution in the HLCT state of Silole‐1DPA‐TRZ is realized, making its application in silole‐based OLED with an efficiency breakthrough of ≈9.1% maximum external quantum efficiency (EQEmax).

Heat/mass transfer augmentation in a leading-edge channel with extended ribs

Gas turbine blade leading-edge cooling is critical due to a high thermal load in the stagnation region. It requires a significant portion of total cooling air supplied to the turbine blade. In order to meet the durability requirement, various cooling schemes are applied. One of the most commonly found in the leading-edge cooling passage is a rib-turbulator design. In this study, a novel rib-turbulator design is investigated for flow and heat transfer characteristics using numerical and experimental methods. The test section was designed to simulate a realistic internal passage, as a triangular channel with a rounded leading-edge. The rib turbulators are installed in a staggered manner. Numerical analyses were performed using a commercial CFD tool, ANSYS CFX. Naphthalene sublimation method was adopted to measure local convective heat/mass transfer distributions. The main geometrical parameter of interest was the extension length of the rib-turbulators (l/e = 0.0, 1.0, 1.5) in the leading-edge region. Based on the parametric study, the optimized case was found, and its heat transfer performance was compared to the baseline (conventional) case. The Reynolds number varied from 20,000 to 40,000. The optimized case showed a 12.7% better heat transfer performance in the leading-edge region than the baseline case at the Reynolds number 30,000 case.

Features of Anti-crisis Financial Support for Regions in Russia

The article examines the Russian central government’s choice of anti-crisis support measures for its regions. Federal transfers and budget loans, which have been the two most common instruments for providing fiscal assistance to support regions in crisis, are studied in detail. Financial assistance to the regions enables regional budgets to remain balanced, but it may also weaken fiscal incentives. Econometric analysis is applied to assess the effects of supporting regional budgets when their tax and non-tax revenues decreased during the period from 2006 to 2020. Special attention is paid to identifying the differences in support for the regions during the crises of 2008–2009, 2014–2015 and 2020, and the differences in the policies pursued during those crisis periods are subjected to various tests. The results of evaluating the econometric models using data from 2006 to 2020 indicated that there was no significant weakening of fiscal incentives outside the crisis periods. Support increased by no more than 20 kopecks per 1 ruble when regional tax and non-tax revenues decreased outside the crisis periods, although that result is not replicable across changes in the regions sampled and in specifications. The federal support policy for the regions in 2009 and 2020, in contrast to 2015, was mostly a response to the amount of the shortfalls in regional budget revenues. The distribution of transfers in 2020 was largely aimed at compensating for reductions in budget revenues. The paper also highlights the difference in the federal policy depending on a given region’s budget capacity: support for wealthy regions was aimed at compensating for shortfalls in income, while support for low-income regions did not correlate with reduced income. The results of this study are correlated with earlier estimates based on Russian data and extend them with an analysis of the 2020 crisis

Using a Multi-Inlet/Outlet Manifold to Improve Heat Transfer and Flow Distribution of a Pin Fin Heat Sink

Abstract The increased power consumption and continued miniaturization of high-powered electronic components have presented many challenges to their thermal management. To improve the efficiency and reliability of these devices, the high amount of heat that they generate must be properly removed. In this paper, a three-dimensional numerical model has been developed and experimentally validated for several manifold heat sink designs. The goal was to enhance the heat sink's thermal performance while reducing the required pumping power by lowering the pressure drop across the heat sink. The considered designs were benchmarked to a commercially available heat sink in terms of their thermal and hydraulic performances. The proposed manifolds were designed to distribute fluid through alternating inlet and outlet branched internal channels. It was found that using the manifold design with 3 channels reduced the thermal resistance from 0.061 to 0.054 °C/W with a pressure drop reduction of 0.77 kPa from the commercial cold plate. A geometric parametric study was performed to investigate the effect of the manifold's internal channel width on the thermohydraulic performance of the proposed designs. It was found that the thermal resistance decreased as the manifold's channel width decreased, up until a certain width value, below which the thermal resistance started to increase while maintaining low-pressure drop values. Where the thermal resistance significantly decreased in the 7 channels design by 16.4% and maintained a lower pressure drop value below 0.6 kPa.

Local heat/mass transfer distributions on the bottom surface of a cavity exposed to an approaching turbulent boundary layer: Aspect ratio effects

We investigate convective transport from the bottom surface of rectangular cavities of depth d exposed to an oncoming boundary layer flow, using experimental and numerical techniques. The effects of cavity width W are explored for cavities with different lengths L in the downstream direction. Depending on the value of L/d (0.52≤L/d≤10), the approaching boundary layer separates and reattach on the bottom surface and establish a new boundary layer, or skims past the open face of the cavity. This results in significantly different convective transport coefficient distributions on the bottom surface. As cavity width is reduced, three-dimensional effects arise, with interaction of vortex systems on the cavity floor. Detailed spatial distributions of the transport coefficient are captured using a mass transfer technique based on naphthalene sublimation. Further insight into the flow structure responsible for the observed distributions is gained through numerical simulations using a k−ω SST model that is first validated using the experimental results by using a heat/mass transfer analogy factor. Flow streamlines from the computations are used to explain how the time averaged streamlines affect the heat transfer at the bottom surface.

Scientific discussion on the essence of state financial regulation of socio-economic inequality in modern conditions

The article is devoted to the analysis of contemporary problems and peculiarities of regulating socio-economic inequality during the crisis and describes the financial crises’ impact mechanism on the state financial regulation evolution of economic inequality.In times of economic crises developed countries make unconditional distributions of money transfers to households to stimulate demand. New liquidity is distributed across the world economy, launching inflationary processes against the backdrop of significant problems with the supply of raw materials and materials due to the consequences of the COVID-19 pandemic. Public interest to the problem of growing socio-economic inequality is increasing along with the rise in the number of dollar millionaires and the financial assets prices. In many ways, this phenomenon is associated with the financial regulation specifics of the economy during times of crises.As a result of the study, the specifics and paradoxes of modern state financial regulation of economic inequality during times of crises have been substantiated, recommendations for state financial regulation of socio-economic inequality during the crisis have been formulated. Regulators should pay particular attention to the top 10 % of the population, for whom there are now many opportunities for tax optimisation and avoidance, with the result that even theoretically effective progressive tax systems do not work properly in practice. Developed countries should promote international tax cooperation to solve this problem, and developing countries should focus on improving their progressive tax systems.

Numerical Simulation On the Perforation Response of Pressurized Pipe Elbows Under Destructive Impact Loading

Abstract Pipe elbows are essential connection components between the storage terminal and conveying pipelines in the petrochemical industry, which are prone to rupture and perforation under various potential impact loads. In this paper, the rupture and perforation responses of pressurized pipe elbows subjected to transverse impact loads were systematically investigated. Perforation phenomena of pipe elbows were qualitatively analyzed to identify the failure modes and features. Perforation mechanisms of mode transition, transient deflection, velocity variation, energy transfer, and stress distribution were systematically discussed. Extensive parametric studies were performed to investigate the deflection and mechanical responses. Parametric equations were established to describe the critical impact resistance. These results revealed the perforation phenomena and impact limits of pipe elbows subjected to impact loads, which are informative for protection design and damage assessment of pressurized pipe elbows.

Active cooling of photovoltaic (PV) cell by acoustic excitation in single-dimpled internal channel

Solar energy is widely advocated by many countries which is the most popular renewable energy. To get the higher efficiency of the photovoltaic (PV) cell, enhancing cooling performance of the coolant channel is important. In this study, the effect of acoustic excitation was analyzed to enhance the cooling performance of internal channel imprinted with single-dimple for solar PV cell system. Various acoustic-excitation frequencies were compared for the optimized cooling performance of dimple-imprint channel. All experiments were conducted under laminar-flow conditions. The experiments indicated that a Strouhal number of 1.1 corresponding to a similar frequency of the vortex shedding within the dimple cavity was most-effective to enhance cooling performance. By analyzing the local heat/mass transfer distributions, the effect of acoustic excitation can be clearly noticed within the dimple cavity where vorticities formed. In the aft-plateau region, heat/mass transfer gradually decreased and the effect of acoustic excitation was minimal. Overall, the area-averaged heat/mass transfer was enhanced by 68% at St = 1.1. Furthermore, when the acoustic excitation was adopted, the area-averaged heat/mass transfer was enhanced by 26–35% in other frequency cases. It was concluded that an appropriate acoustic-excitation frequency could effectively improve the cooling performance of a single-dimple imprinted channel. In the end, the efficiency of PV cell will be enhanced by adopting the acoustic-excitation with dimple imprint cooling channel.

Directional effects in plasmon excitation and transition radiation from an anisotropic 2D material induced by a fast charged particle.

We present a relativistic formulation of the energy loss of a charged particle traversing an anisotropic layer under arbitrary angle of incidence. We use a model for the conductivity tensor describing doped phosphorene, which supports plasmon polariton modes (PPMs) that exhibit a topological transition between elliptic and hyperbolic iso-frequency dispersion curves in the THz to the mid-infrared (MIR) frequency range. The total distribution of the momentum transfer and energy loss of the charged particle goes to excitation of the PPMs followed by their decay in phosphorene (Ohmic losses) and the energy that is emitted as transition radiation (TR). We show that the elliptic modes are efficiently excited in the THz range by relativistic particles, but the corresponding Ohmic distributions do not exhibit significant anisotropy. Contrastingly, hyperbolic modes are efficiently excited in the MIR range by slow particles moving under oblique incidence, producing Ohmic distributions that show strong directionality of propagation with large wavevectors associated with the asymptotes of the hyperbolic dispersion curves. The most dramatic effects of the anisotropic layer conductivity are seen in the angular spectra of the TR, with quite distinct and unexpected shapes of the radiation patterns emitted at the THz and MIR frequencies, even for a normal incidence of the charged particle. Those patterns are substantially skewed for oblique incidence, when they show a marked anisotropy relative to the principal axes of the layer. Such a rich variety of the TR spectra should be readily observable via angle-resolved measurements in a transmission electron microscope.

Investigation of Heat Transfer and Pressure Distribution in Power Law Fluids Flowing through a Rectangular Channel Blocked by a Single Heated Circular Cylinder at Inlet

In this paper, the flow of a power law fluid has been investigated for Newtonian and non‐Newtonian fluids with the temperature distribution in a rectangular channel containing a heated circular cylinder near the inlet with different blockage ratios. The generalized non‐Newtonian power law model coupled with the energy equation is solved numerically, considering power law index in the range of 0.8 ≤ n ≤ 1.2 and Reynolds number in the range from 1000 to 10000. A heated circular cylinder is fixed near the inlet of the channel with blockage ratios (from radius to the height of the channel) of 1 : 10, 2 : 10, and 3 : 10 The governing partial differential equations coupled with energy equation are discretized to investigate the simulation of the current problem with finite element‐based software of COMSOL Multiphysics 5.4. The results are shown with the help of surface plots, tables, and graphs. The computational results for maximum and minimum pressure around the cylinder, temperature along the center line of the cylinder, and local Nusselt number are specially discussed in detail.

Characteristics of embedded triple screw pump based on thermal-fluid-structure coupling

To accommodate special applications where installation space is limited and noise and vibration requirements are high, a new triple screw pump structure was proposed, which was integrated into a servo motor. The design optimizes the profile of the master and slave screws of the embedded triple screw pump. The temperature and pressure fields of the embedded triple screw pump, as well as the heat transfer and pressure distribution between the fluid in the pump and the screw, were investigated through a thermal-fluid-structure approach. The deformation and stresses of the screw were compared for three operating conditions: temperature loading, pressure loading, and thermal-fluid-structure coupling. The results show that the deformation and stresses in the screw tended to increase with increasing pressure and temperature and the pressure load caused more significant deformation and stresses in the screw than the temperature load. The screw deformation caused by pressure loading was found to be the main factor affecting the thermal-fluid-structure coupling. The screw deformation after coupling was smaller than the sum of the screw deformation caused by individual temperature and pressure loads, and the stress values were the same. The results indicate that the coupling action weakens the deformation and stresses in the master and slave screws.

Fiscal redistribution, social welfare and income inequality: ‘doing more’ or ‘more to do’?

ABSTRACT This paper embeds the analysis of fiscal redistribution (FR) within the standard social welfare framework (SWF), which lends itself to a transparent and practical evaluation of the determinants of FR. Differences in FR are decomposed into differences in fiscal effort (the magnitude of redistributive transfers) and in fiscal progressivity (the distribution of net transfers across different income groups). Progressivity is further decomposed into targeting performance (the share of net transfers accruing to lower-income groups) and targeting returns (the social returns to targeting due to differences in the initial income inequality). This highlights the possibility that countries with the exact same redistributive effort (fiscal effort and targeting performance) can have very different levels of FR simply because they have very different levels of initial income inequality. High levels of FR in a country may therefore reflect that it has ‘more to do’ (high initial inequality) as opposed to it ‘doing more’. To illustrate, the paper decomposes differences in FR across 28 EU countries to isolate the importance of initial income inequality in explaining these differences. It also shows how the SWF can be straightforwardly used to test for the existence of the Paradox of Redistribution.

Evidence of the effect of strong stripping channels on the dynamics of the Li8+Ni58 reaction

The $^{8}\mathrm{Li}+^{58}\mathrm{Ni}$ collision is investigated at 23.9, 26.1, 28.7, and 30 MeV bombarding energies. Quasielastic angular distributions and the singles $^{7}\mathrm{Li}$ angular and energy distributions are presented. Coupled-reaction channels (CRC) calculations, which include the coupling of the elastic channel to $^{59}\mathrm{Ni}=^{58}\mathrm{Ni}\phantom{\rule{0.16em}{0ex}}+\phantom{\rule{0.16em}{0ex}}n$ states above and below the neutron threshold, provide a simultaneous description of the quasielastic and transfer distributions and evidence the strong effect of the one-neutron transfer/breakup channels on the quasielastic scattering. The $^{7}\mathrm{Li}$ angular and energy distributions have been also successfully analyzed combining the continuum discretized coupled channels (CDCC) method, for the elastic breakup, and the IAV model of Ichimura, Austern, and Vincent [Phys. Rev. C 32, 431 (1985)], for the nonelastic breakup. These calculations indicate that most of the $^{7}\mathrm{Li}$ yields are due to nonelastic breakup contributions (transfer), whereas elastic breakup plays a minor role.

Bond position function between deformed steel bars and early-age cementitious grout

Pullout tests for the deformed steel bars in early-aged cementitious grout by considering the variables of testing ages, cover thicknesses, and diameters of steel bar were conducted, and the local bond stress–slip relationship at different positions of the anchorage length of steel bar was studied. Results indicated that, with the increase of testing age, the load-slip curves exhibited a higher ultimate load and had steeper ascending and descending branches; however, the slippage at the ultimate load exhibited a decreasing trend. Moreover, with the increase of cover thickness and diameter of steel bar, the ultimate load of pullout specimens increased obviously, while the corresponding slips generally had no obvious correlations. According to an analysis of the measured rebar strain, the distributions of the steel stress and bond stress as well as the relative slip along the embedded length were obtained under different external loads. Steel stress transfer and bond stress distribution parameters were introduced to characterize the nonuniformity of the distributions of the steel stress and bond stress along the steel bar, and the effects of the testing age, cover thickness, and diameter of steel bar on these two parameters were analyzed. Results showed that the both of these two parameters increased with the increasing tensile load, testing age, and cover thickness and with the decreasing diameter of steel bar. Thereafter, the local bond stress-slip relationships along the anchorage length and position functions reflecting the variations of these relationships were proposed.

Impingement/effusion cooling with a hollow cylinder structure for additive manufacturing: Effect of channel gap height

The present study is to investigate the effect of gap height on heat/mass transfer for impingement/effusion cooling of gas turbine hot components, using a hollow cylinder structure created by three perforated plates with two channels. The detailed local heat/mass transfer coefficients on all surfaces of the structure are measured in the test section using a naphthalene sublimation method. Flow characteristics in the structure are revealed using a numerical simulation such as jet impingement, wall jets, and toroidal vortices. The hole spacing (P/D) and thickness of plate (t/D) in the present study are 6 and 1, respectively. The various gap height ratios, which mean the ratios between the gap height of the first channel and that of the second channel, are 1:4 (0.2D-0.8D), 1:1 (0.5D-0.5D), and 4:1 (0.8D-0.2D). Depending on the gap height ratios, heat/mass transfer distributions are obtained differently on each surface of the structure. The area-averaged Sherwood number on each surface shows a large variation ranging from 27% reduction in UM of the Case 3 and 42% increase in UB of the Case 3 with different gap heights at the Reynolds number (ReD) of 7,000. Considering the benefits of heat/mass transfer augmentation and the drawbacks associated with an increase in pressure drop, the structural configuration of the first channel of low gap height and the second channel of high gap height has the highest thermal performance factor, with an improvement of 4.8% at ReD = 7,000. The scale of gap height and wall thickness of the gas turbine hot components should be selected in terms of the total blade wall thickness, number of multi-layers, and manufacturing tolerance in additive manufacturing. Therefore, as gap height for the channel in the laminated structure is limited, the case of the gap height ratios of 1:4, which is the low gap height for the first channel and the high gap height for the second channel, offers the best cooling performance for gas turbine components compared to its counterpart having a high gap height of the first channel and a low gap height of the second channel.

Expenditures on National Projects in the Public Spending System

The paper is devoted to analyzing the category of “public expenditure”, its comparative analysis with the category “budget expenditures” in doctrinal understanding and according to the legislative definition. On the basis of relative and absolute data, the author highlights the trend towards an increase of the share of national projects in the overall structure of public expenditure, as well as the trend towards annual increases in direct expenditures from the federal budget. The author concludes that it is necessary to consolidate the thesis on priority financing of national projects in the allocation of budgetary funds at the federal law level. The author analizes the place of allocations for the implementation of national projects in the updated Budget Classification and determines a number of features of budget financing of national projects. The paper elucidates the legal mechanisms of adjustment of national projects financing on the basis of the legislation, highlights the modernization of financial instruments in the field of public procurement, trends in the field of distribution of the inter-budgetary transfers with co-financing. The author highlights the importance of retrospective analysis of information on the performance of budgetary allocations by the key spending units of federal budget funds in the previous fiscal year for the purpose of prospective planning. The conclusion is made about facilitating the integration of the format of national projects into the system of strategic planning with the medium and long-term perspective.

Surface Temperature Distribution Characteristics of Marangoni Condensation for Ethanol–Water Mixture Vapor Based on Thermal Infrared Images

Marangoni condensation is formed due to the surface tension gradient caused by the local temperature or concentration gradient on the condensate surface; thus, the investigation of the surface temperature distribution characteristics is crucial to reveal the condensation mechanism and heat transfer characteristics. Few studies have been conducted on the temperature distribution of the condensate surface. In this study, thermal infrared images were used to measure the temperature distributions of the condensate surface during Marangoni condensation for ethanol–water mixture vapor. The results showed that the surface temperature distribution of the single droplet was uneven, and a large temperature gradient, approximately 15.6 °C/mm, existed at the edge of the condensate droplets. The maximum temperature difference on the droplet surface reached up to 8 °C. During the condensation process, the average surface temperature of a single droplet firstly increased rapidly and then slowly until it approached a certain temperature, whereas that of the condensate surface increased rapidly at the beginning and then changed periodically in a cosine-like curve. The present results will be used to obtain local heat flux and heat transfer coefficients on the condensing surface, and to further establish the relationship between heat transfer and temperature distribution characteristics.

Influence of braking on dynamic stability of car-trailer combinations

The influence of braking on dynamic stability of a car-trailer combination (CTC) is studied in this paper. The braking is simply modeled and integrated into a single-track model (STM) with a single-axle trailer. On this basis, some fundamentals and analysis results related to system dynamic stability are given through simulation. Furthermore, it is found that the axle load transfer and braking force distribution have a great influence on system dynamic stability. In order to further analyze the influence of these two factors, both of the braking force distribution and the pitch motion are considered in the modeling. Finally, the ideal braking force distribution domain is proposed. Results can be adopted to explain the experimental phenomenon and serve as a guideline for the differential braking strategy in stability control of the CTC.

On the Blast Mitigation Ability of Multiple V-Shape Deflectors

This paper presents a 2D numerical study of v-shape deflectors subjected to high explosive charge detonation. The literature provides many papers concerning the appropriate geometry of blast protection deflectors. Such structures require a relatively high distance between the ground and the vehicle chassis. In most cases, the placement of a deflector is not possible or it cannot cover the whole area under a chassis. An interesting question that arises is to what extent a set of small deflectors would be able to mitigate blast effects. The content of this paper constitutes an answer to this question. Three analyses were conducted: (1) multiplication of triangle components, (2) effect of deflector size, and (3) geometry-induced shock dynamics. The problem was solved with the use of modelling and simulation methods, in particular, CFD-FEM implemented in the LS-DYNA code. It was considered a plain issue in computational fluid dynamics, where space discretization for each option was built with two-dimensional elements to ensure efficient calculations. Deflectors were described using a rigid wall boundary condition, and an adequate simplified detonation model was assumed. The primary measure of the results was reaction force history, with momentum transfer and pressure distribution maps considered supplementary. The studies performed showed that both minimizing the v-shape deflector size and surrounding it with adjacent structures had a negative impact on its blast mitigation effectiveness. However, for each multi-v-shape deflector, some improvement was present, and, therefore, in situations where the installation of a typical protector is not possible due to dimensional requirements, it may offer a compromise solution.

Массоперенос и диффузионное распределение элементов при неравновесной аустенитизации стали 20Х13

Массоперенос и диффузионное распределение элементов при неравновесной аустенитизации стали 20Х13