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When considering disintegration of spatial networks, the topological relationships between nodes and their geographical positions are taken into account. In the case of regional attacks, the targeted nodes are determined based on the size of the region and the geographical relationships between nodes. In this paper, a new metric is proposed on top of region centrality (RC) to describe the importance of nodes within local regions in spatial networks. We define the weighted sum of the number of connections between nodes within a local region and the number of connections between nodes within the local region and nodes outside the local region as local connectivity. This metric integrates topological information with geographical information. From a mathematical perspective, RC is a special case of local connectivity. In addition, we propose a hybrid spatial network disintegration strategy based on two metrics, namely local connectivity and RC. From experimental results, our strategy outperforms traditional approaches and demonstrates a stronger ability to completely disintegrate the network. [ABSTRACT FROM AUTHOR]

The performance of the perturbed‐chain statistical associating fluid theory‐type equations of state (PC‐SAFT‐type EOSs) is compromised in predicting properties of pure compounds in the critical region. In our previous research, we introduced an improved volume‐translated rescaled PC‐SAFT EOS (VTR‐PC‐SAFT EOS) by incorporating a dimensionless distance‐function. Such VTR‐PC‐SAFT EOS is built based on a critical point‐based PC‐SAFT EOS that can reproduce the critical temperature, critical pressure, and critical molar volume of pure compounds. VTR‐PC‐SAFT EOS is found to significantly improve the accuracy of phase behavior predictions in both critical and noncritical regions for pure compounds. In this study, we assess the performance of VTR‐PC‐SAFT EOS in reproducing the critical and noncritical properties of 251 pure compounds, encompassing 20 distinct chemical species. The testing results indicate that, compared to the other three PC‐SAFT‐type EOSs, the VTR‐PC‐SAFT EOS can consistently provide more accurate representations of critical and noncritical properties of 251 pure compounds. [ABSTRACT FROM AUTHOR]

Based on the previously developed simplified method for constructing the equation of state for liquid and vapor phases, the thermodynamically consistent analytical equation of state for liquid and gaseous nitrogen in the molecular cryogenic conditions is obtained. While constructing the equation of state, the Mie–Gruneisen form was used as the sum of potential and thermal components for pressure and internal energy. The cold components of pressure and internal energy are described by a potential of the Born–Meyer type. For the thermal components, a simplifying approximation is adopted, which follows from the condition for the constant heat capacity and the dependence of Gruneisen function on the volume. When determining the equation of state for the vapor and liquid phases of nitrogen, the method of minimizing the standard deviation of the experimental and calculated data on isothermal compressibility, including the critical region and the phase equilibrium line, was used. The resulting equation of state for nitrogen makes it possible to study the phenomena associated with the processes of evaporation and condensation of nitrogen when modeling multiphase flows, taking into account interfacial heat and mass transfer under conditions of low pressures and cryogenic temperatures. [ABSTRACT FROM AUTHOR]

The introduction of renewable energy introduces operational challenges for the modern multi-energy system. To accommodate the uncertainty, this paper proposes an online probabilistic energy flow for the hydrogen-power-heat system. First, a hydrogen-power-heat system model is established to depict the interdependency of multiple energy, in which hydrogen fuel cells interconnect hydrogen, power, and heat systems by converting the hydrogen into power and heat. The probabilistic energy flow is further built considering the uncertain wind power. An efficient algorithm based on multi-parametric programming (MPP) is proposed to enhance the computational performance of probabilistic multi-energy flow for online applications. The parameter region of the probabilistic multi-energy flow in MPP model is divided into multiple critical regions (CR). Each CR reveals a unique mapping relationship from uncertain wind power to system optimal solutions. Probabilistic energy flow could be quickly calculated based on mapping relationship rather than solving optimization problem. Therefore, the proposed method could be applied in online energy flow calculation. Numerical results tested on a 6–6-8 system and an improved 40–118 − 13 system validate the accuracy and efficiency of the proposed method in probabilistic energy flow calculation. • Online rapid computational method for probabilistic energy flow is proposed for hydrogen-power-heat system. • Parameter hyperspace of uncertain wind power in multi-parametric programming is divided into a set of critical regions. • Mapping relationship is applied to quickly obtain optimal solution. • Two test systems are provided to validate effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In recent years, the CO 2 super/transcritical power cycle has gained significant attention as the most widely studied power cycle. The accurate thermodynamic properties data is very important for cycle design and performance analysis. In this study, the Kiselev's crossover method based on the renormalization group theory is used to improve the classic SRK equation of state in non-critical region and reproduce the critical fluctuation phenomenon in critical region. The nonlinear equations method and interior-point method are used in the parameter fitting of crossover SRK (CSRK) to get the optimal parameters. The replaced method avoids the problem that Newton iteration method is prone to divergence and falling into local optima. The thermodynamic properties of CO 2 including the VLE properties, heat capacity and speed of sound are calculated by CSRK, respectively. The results show the calculation of the non-critical region is improved, and the critical fluctuation phenomenon in the near-critical region is described accurately, especially the second-order thermodynamic properties calculation results is improved from 3.65 % to 2.80 % compared with our previous work. [ABSTRACT FROM AUTHOR]

In many-to-one patterns of wireless sensor networks, the energy hole problem is a crucial issue that ultimately causes to reduce the network lifetime considerably. Since the closer nodes locating to the base station/sink spend more energy than the nodes in the outer regions, as a result, these nodes will die soon and fast. During the last decades, several schemes have been proposed to overcome the energy holes and enhance the network lifetime. Based on previous related works in uniform node deployment strategies, the innermost layer is prone to energy holes due to high traffic load compared with outer layers. However, recognition of the critical region (the region with the most energy holes in the network) is an important issue that has not been addressed in non-uniform node deployment strategies yet. Likewise, complete energy balancing has not been taken into consideration in most prior studies. Therefore, in this paper, first, we propose an equation to find the critical region in many-to-one networks; meanwhile, we present equations to gain the required initial energy in these networks in order to maximize the network lifetime and remove the energy hole problem by completely balancing energy consumption and with no extra nodes. Afterwards, the proposed model is compared to the other previous strategies based on two scenarios. The final results indicate that the proposed method can maximize the network lifetime. Besides, it requires less total energy than other previous works, including Ferng and q-switch strategies. [ABSTRACT FROM AUTHOR]

Trisomy 18, commonly known as Edwards syndrome, is the second most common autosomal trisomy among live born neonates. Multiple tissues including cardiac, abdominal, and nervous systems are affected by an extra chromosome 18. To delineate the complexity of anomalies of trisomy 18, we analyzed cultured amniotic fluid cells from two euploid and three trisomy 18 samples using single-cell transcriptomics. We identified 6 cell groups, which function in development of major tissues such as kidney, vasculature and smooth muscle, and display significant alterations in gene expression as detected by single-cell RNA-sequencing. Moreover, we demonstrated significant gene expression changes in previously proposed trisomy 18 critical regions, and identified three new regions such as 18p11.32, 18q11 and 18q21.32, which are likely associated with trisomy 18 phenotypes. Our results indicate complexity of trisomy 18 at the gene expression level and reveal genetic reasoning of diverse phenotypes in trisomy 18 patients.

Taiwan is a world-leader in wafer foundry services and IC packaging and testing. Wire bonding is a crucial process in the overall IC-packaging industry chain. Thus, this paper proposes a process-quality evaluation model for wire bonding with multiple gold wires. We chose process quality indices as a tool of evaluation fully mirroring process yield and quality levels. These indices contain unknown parameters and thus require sample data to estimate. We first derived the uniformly minimum variance unbiased estimator of the indices and calculated the upper confidence limits of the indices based on DeMorgan's theorem and Boole's inequality. The upper confidence limits of the indices were then employed to create a confidence interval-based fuzzy membership function, in order to improve the accuracy of estimation as well as solve the problem of uncertainty of the measured data. Next, we obtained the fuzzy critical value and used index estimates and the fuzzy critical value to establish fuzzy test rules. Next, we marked the fuzzy critical value on the axes of a radar chart, which is a visualization evaluation tool, and connected neighboring critical points to create a critical region in the form of a regular polygon. The observed values of the indices were then marked on the axes to produce a visualized fuzzy radar evaluation chart. This fuzzy radar evaluation chart has a solid foundation in statistical inference, and evaluation rules were established using precise fuzzy test methods. Not only is this fuzzy radar evaluation chart easy to use, but it also reduces the chance of misinterpretations made by sampling errors, so that the accuracy of evaluation can be enhanced.

In the face of the budget cuts and increased size of industry infrastructure, one of the top priorities for industry infrastructure protection is to identify critical regions by vulnerability analysis. Then, limited resources can be allocated to those critical regions. Unfortunately, difficulties can be observed in existing approaches of vulnerability analysis. Some of them are unavailable due to the insufficient data. Others are susceptible to human biases. Here, we propose an approach to overcome these difficulties based on the location data of failure events. The critical geographic regions are determined by the risk ranking of different candidate regions. Risk is calculated by integrating the probability of the failure event occurring (risk uncertainty) and total failure cost (the severity of failure consequences) in each candidate region. By changing the modeled object from the components to the region where the whole industry infrastructure is located, it collects the rarely failure events which are dispersed in different positions of the industry infrastructure to provide sufficient data, then the probability can be obtained by using a Poisson point process and kernel density estimation. Meanwhile, the application of hypothesis testing avoids the susceptibility of the approach to human biases by verifying the correctness of the assumptions used in the approach. Finally, a case study of this approach is performed on a pipeline network in Kansas, USA. In addition to the validation of the feasibility of our approach, risk uncertainty is proven to be less instructive for identifying critical regions than the severity of failure consequences.

[Objectives] The service life of a modern LNG carrier is normally no less than 40 years,which makes the hull bear much more structural alternating cyclic stress than other types of merchant cargo ship with an average service life of 20 to 25 years. There fore,it is necessary to perform fatigue strength analysis of LNG carriers.[Methods] In this paper,The study of the fatigue strength of large membrane LNG carriers such as a 170 000 m3 LNG is conducted adopting the spectral fatigue analysis method. Based on the wave environment of the North Atlantic Ocean and a 40-year designed fatigue life goal with full loading departure and ballast departure loading conditions,with optimization in some areas,the cumulative fatigue damage and fatigue life are calculated according to spectral analysis.[Results] The results show that,the optimized fatigue strength of the ship structure meets design requirements.[Conclusions] This paper proposes the design optimization of critical regions and corresponding hotspots,and puts forward recommendations for quality control during construction and operation to improve structural fatigue performance,thereby providing references and support for the study of large membrane LNG carrier fatigue strength and related hull quality control in the construction and operation stages.

Robust look-ahead dispatch (RLAD) is essential to manage uncertainties in power systems. As its key step, the worst-case scenario identification (WCSI) problem is cast to a max-min program. This computationally intensive procedure has to be performed repeatedly, impairing the computational efficiency of RLAD. To address this issue, an efficient RLAD scheme incorporating critical region preparation in gap time is proposed. The computation burden is mostly transferred from the online decision stage to the gap time via a customized technique based on multi-parametric programming. The accuracy of computing the critical regions is validated by the test in a six-bus system, and the proposed method is shown to cut down 21% of total iterations and save computational time dramatically by the test in a practical-scale system in Northeastern China. [ABSTRACT FROM AUTHOR]

We develop a passive control strategy for suppressing thermoacoustic instability in a bluff-body stabilized premixed turbulent combustor. When the equivalence ratio is varied, there is a transition from combustion noise to thermoacoustic instability via intermittency in the combustor. We perform simultaneous acoustic pressure, 2D-PIV, and CH * chemiluminescence measurements to capture the pressure fluctuations, the velocity field, and the heat release rate (HRR) field during the transition. We measure the spatial distribution of the amplitude of turbulent velocity at the acoustic frequency, time-averaged vorticity, time-averaged HRR, and Rayleigh index and identify various regions of significance. We implement a passive control strategy by targeting these regions with a steady injection of secondary micro-jet of air to optimize the injection location and determine the critical region. Targeting the critical region with secondary air leads to greater than 20 dB suppression of the dominant thermoacoustic mode. We observe that the coherent structure forming from the shear layer following the dump plane gets suppressed, leading to an incoherent spatial distribution of HRR fluctuations. We find that the turbulent velocity amplitude correctly identifies the critical region for optimized passive control during thermoacoustic instability. In contrast, the Rayleigh index identifies the region of the most significant acoustic driving; however, it does not identify the region most sensitive to control. Finally, we extend our analysis by determining the spatial distribution of the Hurst exponent measured from the turbulent velocity field. We show that the Hurst exponent identifies the critical region during thermoacoustic instability and intermittency, unlike the other physical measures. Thus, we develop a smart passive control method by combining the need for finding critical regions in the combustor with the predictive capabilities of the Hurst exponent. [ABSTRACT FROM AUTHOR]

Fibroblast growth factor receptor‐like 1 (FGFRL1) encodes a transmembrane protein that is related to fibroblast growth factor receptors but lacks an intercellular tyrosine kinase domain. in vitro studies suggest that FGFRL1 inhibits cell proliferation and promotes cell differentiation and cell adhesion. Mice that lack FGFRL1 die shortly after birth from respiratory distress and have abnormally thin diaphragms whose muscular hypoplasia allows the liver to protrude into the thoracic cavity. Haploinsufficiency of FGFRL1 has been hypothesized to contribute to the development of congenital diaphragmatic hernia (CDH) associated with Wolf‐Hirschhorn syndrome. However, data from both humans and mice suggest that disruption of one copy of FGFRL1 alone is insufficient to cause diaphragm defects. Here we report a female fetus with CDH whose 4p16.3 deletion allows us to refine the Wolf‐Hirschhorn syndrome CDH critical region to an approximately 1.9 Mb region that contains FGFRL1. We also report a male infant with isolated left‐sided diaphragm agenesis who carried compound heterozygous missense variants in FGFRL1. These cases provide additional evidence that deleterious FGFRL1 variants may contribute to the development of CDH in humans. [ABSTRACT FROM AUTHOR]

The temperature dependence of the electric resistivity measured in various magnetic fields was analyzed by the vortex glass theory and the thermally activated flux motion (TAFM) theory. The vortex glass-to-vortex liquid (GTL) transition Tg obtained from the analysis shows a temperature dependence of BgT=B01-T/Tcm. The vortex liquid region is divided into the critical region existing in a finite temperature region just above Tg and the TAFM region present in the finite temperature region above it. In the critical region, the activation energy is expressed as Ueff=kBTTc-T/(Tc-Tg), whereas in the TAFM region, the activity energy is expressed as temperature-nonlinear UT,B=U0B1-tq. In the GTL transition, (Ca0.85La0.15)10(Pt3As8)(Fe2As2)5 maintains the 3D vortex structure without exhibiting dimension crossover of the vortex, but Ca10(Pt3As8)((Fe0.92Pt0.08)2As2)5 exhibits the dimension crossover from the 3D vortex glass to the 2D vortex liquid.

Dramatic changes of thermophysical properties in the vicinity of critical point brings significant accelerating effect on the thermodynamic transitions of fluid. This study performs a confined geometric design with CO 2 fluids passing through the critical zone in microchannel. Such a problem formulation combines the compressible Navier-Stokes equations with different property formulations to obtain critical anomaly effects at complex critical transport coefficients. Three equations of state (van der Waals (vdW), Redlich-Kwong (R-K) and Peng-Robinson (P-R) state equations) and their corresponding thermodynamic relations are derived in solving the governing equations of flow and heat transfer equations. Basic results are found to be consistent with theoretical asymptotic analysis, with linearly curves of pressure and a sudden shift of density (425 kg/m3–502 kg/m3) and velocity (0.82 m/s to 0.97 m/s) profiles when the microchannel flow across the critical region. The cascade effect between weakened radial thermal conductivity (λ ∼ (ρ – 1)-1/2, c p ∼ (ρ - 1)−2) and enhanced fluid expansion (β p ∼ (ρ - 1)−2) in the critical region is also shown to cause a sharp negative transition in temperature. In addition, the simulations demonstrate a qualitative comparison for three state equations, and the distinctions in quantitative terms (negative temperature value are −0.1 (vdW), −0.17 (R-K), and − 0.23(P-R)) are found to originate from stronger divergence characteristics (the specific heat c p and thermal expansion coefficients β p) in P-R gases than vdW and R-K gases. [ABSTRACT FROM AUTHOR]

The integration of multienergy systems (MES) provides an important opportunity to increase the technical, economic, and environmental performance of the overall system compared with separately operated energy systems. The operation of district MES encounters numerous uncertainties such as fluctuations in energy prices as well as loads in different energy forms. In this paper, we formulate a probabilistic optimal energy flow (P-OEF) model of a district MES into a linear program (LP) problem based on the linear energy hub model. We propose an improved multiparametric LP (MPLP) based online dictionary-learning approach to efficiently calculate the P-OEF problem. We then derive a generalized critical region theory of the MPLP problem to jointly consider the change of parameters in terms of both the objective function and the constraints of P-OEF in MES. Finally, we explore the physical significance of the MPLP's critical region in the P-OEF problem. We perform a case study to verify the validity and effectiveness of the proposed approach compared to the traditional Monte Carlo approach for the P-OEF of the MES. [ABSTRACT FROM AUTHOR]

With the emerging application of near-critical fluid, the subject of equation of state (EoS) covering the critical point is of great significance as the thermodynamic behavior of fluids near the critical point is different. Although many different EoSs are available for fluids at the moment, the ones which can give good quantitative results are still rare. Therefore, it is essential to have a suitable model for proper prediction of fluids behavior and their thermodynamic properties near the critical region. In this study, the crossover translation, which applies the asymptotic behavior of fluids and scaling laws near and far from the critical point, was used. Thermodynamic properties including density, vapor pressure and isochoric heat capacity of fifteen pure components in the saturated state and single-phase region on different isotherms were investigated near the critical point by Soave-Redlich-Kwong (SRK) equation of state and crossover SRK EoS and the results were compared with experimental data. According to the results, crossover SRK EoS predicted all of the mentioned properties with quantitative accuracy. The average absolute percent deviation (AAPD) of the saturated liquid density, saturated vapor density, density on isotherms, vapor pressure and isochoric heat capacity based on crossover SRK EoS were 0.0060,0.1287, 0.0171, 0.057 and 2.53, respectively. [ABSTRACT FROM AUTHOR]

Approaching the critical region of hydrocarbon + water mixtures will lead to an unusual increment in miscibility. In this research, CPA EoS is satisfactorily applied to predict the properties of three hydrocarbon + water mixtures at near/supercritical temperatures. First, CPA EoS is applied to evaluate the density of pure water and hydrocarbons in a range of pressure at various temperatures. To make a comparison on CPA models, both SRK and PR are accounted in the physical term of the model. In the case of pure hydrocarbons, the effect of volume shift correction (VS) on modeling results is also investigated. Afterwards, CPA EoS is used to predict the density of mixtures and relative volume change of mixing for hydrocarbon rich phase of mixtures at various temperatures. The results revealed that CPA EoS would be a reliable choice to predict complex behavior of hydrocarbon + water mixtures in a wide range of pressures and temperatures. • SRK/PR-CPA are applied to estimate excess volume of water + hydrocarbon mixtures at high temperatures near critical region. • Impacts of pressure and temperature change, and volume shift on density and excess volume of mixtures are investigated. • The CPA models can predict densities of these complex mixtures with/without tuning the adjusting parameters. [ABSTRACT FROM AUTHOR]

The reliability analysis of structural systems is generally difficult when limit state function (LSF) is implicitly defined especially by black-box models in engineering. To balance analysis efficiency and accuracy, an improved approach named BIS-FC is proposed in this paper based on the Beta-spherical importance sampling (BIS) framework with the innovative concept of critical region defined by combination with First Order Reliability Method (FORM). The critical region is defined by the hyper-tangent plane of LSF at the Most Probable Point (MPP) and its parallel hyperplanes according to the convex or concave features of LSF, wherein the samples are of both high occurrence probability and high misjudgment risk due to the linearization assumption of FORM. BIS-FC only conducts LSF analysis for the BIS samples located in the critical region, and the other samples are directly identified as safe or failure according to the linearized hyperplanes. Thus large computational cost can be saved compared to the original BIS, and meanwhile, the analysis accuracy can be greatly enhanced compared to FORM. An iterative process is proposed to properly define the critical region, based on which reliability is analyzed sequentially until the stopping criteria for desired estimation error level and stable convergence are satisfied. The algorithms of BIS-FC for both single and multiple MPP situations are developed and testified with six numerical examples and one satellite structural engineering problem. The results demonstrate the effectiveness of BIS-FC regarding good balance between efficiency and accuracy. [ABSTRACT FROM AUTHOR]

Highlights • The thermal-hydraulic performance of a PCHE was investigated numerically. • The effect of sCO 2 thermophysical properties on flow and heat transfer was discussed. • The values of friction coefficient and Nusselt number were compared to the analytical solutions. Abstract A numerical analysis of the developing laminar flow and conjugate heat transfer in a rectangular micro-channel was performed for supercritical CO 2 and liquid sodium as working fluids for better understanding of the flow and heat transfer mechanisms. Three-dimensional Navier-Stokes, energy, and Laplace equations describing simultaneously developing flow and conjugate heat transfer in multiple micro-channels were solved numerically using Fluent code for the parallel- and counter-flow arrangements. The physical and transport properties of CO 2 at supercritical conditions and their influence on fluid flow and heat transfer are presented and discussed. Liquid sodium and supercritical CO 2 (sCO 2) were used as the heat transfer and hot and cold working fluids, respectively. The values of friction coefficient and Nusselt number predicted by the numerical analysis were compared to the analytical solutions from the literature. Numerical results show that large variations in sCO 2 properties in the critical and pseudo-critical regions affect the flow and heat transfer. This effect diminishes for operating conditions (pressure and temperature) further away from the Critical Point. Also, in the fully-developed region the local values of wall shear stress and heat transfer coefficient are not constant, but are strong functions of the local heat flux at the solid-fluid interface which varies due to large variation in sCO 2 properties. [ABSTRACT FROM AUTHOR]

Accurate results for fluids at thermal equilibrium, valid both outside and inside the critical region, are difficult to obtain due to the singular nature of this region. However, for simple models like interacting hard spheres and the Ising model high accuracy has been obtained by use of SCOZA (self-consistent Ornstein-Zernike approximation). Here this approach is extended to one component fluids more generally. Outside the critical region good analytic approximations may be obtained by use of statistical mechanical results that are adjusted to experimental data and/or computer simulations. However, such approximations typically will be of mean field type in the sense that the usual singular behavior in the critical region and in the transition to it, is not present. Here the SCOZA is generalized such that approximations accurate outside the critical region are utilized as basic input in the SCOZA problem. The singular behavior is connected to correlations of increasing range that develop as the critical point is approached. These correlations contribute both to the internal energy and compressibility of the fluid, and they give another contribution to the SCOZA partial differential equation. Accurate results in the critical region are expected to be obtained by adjusting one or a few parameters. • The SCOZA is extended to fluids more generally. Earlier it was developed to improve upon the MSA. • By this extension also equations of state known well outside the critical region, can be input to the SCOZA problem. • The SCOZA gives a rather accurate description of the critical region with its singular behavior. • Solution of the SCOZA problem is expected to give accurate results also in the critical region for the fluid of interest. [ABSTRACT FROM AUTHOR]

The mining risks and the landscape impact on the regional system of the Apuseni Mountains. A region can be considered to be critical, when inside of it can occur or it is likely to manifest imminent risk factors (natural or anthropogenic), possibly triggering some risk phenomena that may have negative consequences and can disturb the functionality and the dynamic equilibrium state of the territorial system, the Apuseni Mountains can be included within such a category, that is the critical regions. In the Apuseni Mountains regional system, act or have acted (with obvious traces present) a number of risk factors that have left their mark on the geographical landscape and especially on its functionality, jeopardizing the viability of the territorial system itself and its future development. These factors are either natural or anthropogenic and their effects will be analyzed further, identifying risk phenomena that they cause and the landscape impact.

The territorial system of the Apuseni Mountains can be considered a critical region from a geo-demographic viewpoint. This is due to two major geo-demographic risks that affect it at present, namely the massive migration, mainly of the young and adult population, and the severe decrease in birth rate, also as a consequence of migration. These two processes determine the main two geo-demographic risks within the Apuseni Mountains: on the one hand, depopulation and the geo-demographic decline of the settlements and, on the other hand, population ageing. The present study aims to analyse the latter by focussing on the Land of the Moţi. Conclusions emphasise a rather severe process of demographic ageing. The rate of the old age group increased from 17.9% in 1992 to 25.2% in 2011. All the 16 administrative-territorial units under analysis recorded an increase in the rate of the old age group. In 2011, the ratio of the extreme age groups (young population/old age group) is above the unit (1) both in the region as a whole and in the majority of its administrative units.

The critical point is the end point of a phase equilibrium curve; liquid and its vapor can coexist under designated points. Close to the critical point, thermophysical properties present clear variations, especially in the region of 0.85 P cr ∼ P cr . Latent heat and liquid density in this region decrease more quickly than in lower-pressure areas, resulting in unique boiling heat transfer behavior. This region is also called the near-critical region. However, only a few scholars have discussed the heat transfer phenomenon; thus, it is difficult to ascertain the near-critical region’s properties and characteristics from extant literature. In the present study, we conduct experimental investigations to explore the specificities of the heat transfer characteristics of carbon dioxide in horizontal flow within the near-critical region in a circular channel with a diameter of 4 mm. The operating pressure ranges from 6.26 MPa to 7.3 MPa with a mass flow rate between 200 and 400 kg/m 2  s, heat flux between 5 and 140 kW/m 2 , and test section inlet temperature of −5 °C. Then, we examine the inner-wall temperature and heat transfer coefficient profiles at different pressures within the near-critical region. The results show that at high heat flux, departure from nucleate boiling (DNB) phenomenon presents with a sudden decrease in the heat transfer coefficient in the subcooled region. The higher the heat flux, the more seriously deteriorating the heat transfer is. Interestingly, the temperature reaches its peak in the post-DNB region rather than at the critical vapor quality point. With an increase in pressure, DNB occurs early with lower vapor quality, and the temperature peak decreases at the given heat flux and mass flux. On the contrary, DNB is delayed with an increase in mass flux. A series of boiling heat transfer correlations in a subcooled region, two-phase flow region, and superheated region are proposed in addition to a new predictive correlation for critical heat flux in the near-critical region at a given mass flux. [ABSTRACT FROM AUTHOR]

This experimental work is aimed at characterizing the effect of scraper board (SB) in reducing the rotating air layer around a grinding wheel and introducing the better method of application of scraper board and fluid delivery into the grinding zone. Zero pressure at the grinding zone is reported to achieve by placing the scraper board at an optimal location along the wheel periphery. The grinding ratio improved by 35.6% and 119%, surface roughness decreased by 36% and 54.2% while the requirement of specific energy is reduced by 50.8% and 57.3% when scraper board is positioned at the critical distance in comparison to the 57.5° position and no scraper board respectively. [ABSTRACT FROM AUTHOR]