Shock Flow Research Articles

Consumer negative opinions on stock returns: evidence from E-commerce reviews in China

This study investigates the significance of e-commerce consumer opinions regarding value in China’s A-share market. By analyzing a large dataset comprising over 18 million online consumer reviews on JD.com, we demonstrate that sentiments expressed in e-commerce reviews can influence stock returns. This indicates that consumer opinions on the e-commerce platform contain valuable information that can impact the stock market. Our findings show that Consumer Negative Sentiment Tendency (CNST) and One-Star Tendency (OST) have a negative effect on expected stock returns, even after controlling for firm characteristics such as market risk, illiquidity, idiosyncratic volatility, and asset growth. Further analysis indicates that CNST demonstrates stronger predictive power within the home appliance industry, under high sentiment conditions, in growth companies, and among firms with lower accounting transparency. We also find that CNST negatively predicts revenue surprises, earnings surprises, and cash flow shocks. These results suggest that consumer opinions and sentiments derived from e-commerce reviews highlight firms’ intrinsic worth and prospects. Future research could explore how firms, including suppliers and logistics companies, can leverage the information conveyed by consumer opinions on e-commerce platforms.

Relativistic Low Angular Momentum Advective Flows Onto Black Hole and Associated Observational Signatures

Abstract We present simulation results examining the presence and behavior of standing shocks in zero-energy low angular momentum advective accretion flows and explore their (in)stability properties, taking into account various values of specific angular momentum, λ 0. Within the range 10−50R g (where R g denotes the Schwarzschild radius), shocks are discernible for λ 0 ≥ 1.75. In the special relativistic hydrodynamic simulation when λ 0 = 1.80, we find the merger of two shocks resulted in a dramatic increase in luminosity. We present the impact of external and internal flow collisions from the funnel region on luminosity. Notably, oscillatory behavior characterizes shocks within 1.70 ≤ λ 0 ≤ 1.80. Using free–free emission as a proxy for analysis, we show that the luminosity oscillations between frequencies of 0.1−10 Hz for λ 0 range as 1.7 ≤ λ 0 ≤ 1.80. These findings offer insights into quasi-periodic oscillation emissions from certain black hole X-ray binaries, exemplified by GX 339-4. Furthermore, for the supermassive black hole at the Milky Way's center, Sgr A*, oscillation frequencies between 10−6 and 10−5 Hz were observed. This frequency range, translating to one cycle every few days, aligns with observational data from X-ray telescopes such as Chandra, Swift, and XMM-Newton.

Effect of artificial viscosity on shocked particle-laden flows for staggered grid Lagrangian methods

Effect of artificial viscosity on shocked particle-laden flows for staggered grid Lagrangian methods

Computational investigation of moving shock interaction with a granular particle curtain using a coupled Eulerian–Lagrangian approach

The objective of this research is to investigate the influence of a moving shock wave on a dense particle curtain using a coupled supersonic Eulerian–Lagrangian solver. The numerical investigation seeks to gain a deeper understanding of the interactions between particles and gas flow through a four-way coupling approach that incorporates interparticle collisions. Upon interaction, the particle curtain undergoes rapid expansion, generating transmitted and reflected shocks. This work focuses on how different particle arrangements affect the fluid flow dynamics and vice versa. By systematically varying the shock Mach number, we elucidate the effects of these interactions across a range of shock strengths, providing a comprehensive picture of the phenomenon. Our findings reveal the crucial role of particle properties and interparticle forces in shaping the dynamics of shock–granular interactions, paving the way for a deeper understanding of multiphase shock flows in various applications.

Investigation of the two-phase flow and heat transfer characteristics with different inlet and outlet arrangements in the ionic liquid compressor for the hydrogen refuelling station

The ionic liquid compressor is a prospective device for hydrogen pressurisation in the hydrogen refuelling station. Ionic liquids are introduced into the compressor chamber between hydrogen and the free piston for lubrication, sealing and cooling. Therefore, it is essential to investigate the two-phase flow and heat transfer since they impact the operational efficiency of the compressor. In this research, numerical simulation using the volume of fluid method was taken out to study the two-phase flow and heat exchange characteristics of hydrogen and ionic liquids in one compression process with four different inlet and outlet arrangements. The results showed that the inlet flow shock caused severe deformation of the phase interface, producing a large number of droplets and bubbles, which significantly enhanced the heat transfer. This deformation was greatly influenced by inlet and outlet arrangements. In general, the axial inlet design caused more obvious interface distortion than the radial one, enlarging the heat transfer area while also raising the risk of the piston being exposed. The recommended structure was the axial decentralised inlet form, which avoided piston exposure while maximizing the heat transfer area, with a hydrogen temperature rise of 16.24 K and a polytropic index of 1.11.

Study of the N2 vibrational relaxation behaviors via the CO rovibrational thermometry.

This paper performed a comprehensive study of the thermal nonequilibrium effects of CO/Ar mixtures with various degrees of N2 additions and probed the N2 relaxation behaviors via the CO rovibrational thermometry. The rovibrational temperature time histories of shock-heated CO/N2/Ar mixtures were measured via a laser-absorption technique, and the corresponding vibrational relaxation data were summarized at 1890-3490K. The measured results were compared with predictions from the Schwartz-Slawsky-Herzfeld (SSH) formula and the state-to-state (StS) approach (treating CO and N2 as pseudo-species). The vibrational state-specific inelastic rate coefficients for N2-N2 collisions were supplemented using the mixed quantum-classical calculations. The StS predictions, informed by experimentally measured pressures, showed good agreement with experimental data. Additionally, the impact of coupling between flow dynamics and StS kinetics behind reflected shock waves was evaluated using two different one-dimensional approaches, which provide limiting bounds (accounting for unsteady flow and end wall effects) in post-reflected shock flow conditions. Moreover, the vibrational relaxation data of the N2-N2 system were modified via sensitivity analysis to improve the performance of the SSH formula. Further analysis highlighted that the vibration-vibration-translation path provides an efficient way for vibrational energy transfer between CO and N2, resulting in almost the same vibrational temperature time histories for CO and N2. Therefore, the N2 relaxation behaviors can be characterized by the CO rovibrational thermometry, considering N2 is infrared inactive. Finally, the heat sink effects and the reflected-shock-bifurcation phenomena were highlighted.

Does Liquidity Management Induce Fragility in Treasury Prices? Evidence from Bond Mutual Funds

Abstract Mutual funds investing in illiquid corporate bonds actively manage Treasury positions to buffer redemption shocks. This liquidity management practice can transmit non-fundamental fund flow shocks onto Treasuries, generating excess return volatility. Consistent with this hypothesis, we find that Treasury excess return volatility is positively associated with bond fund ownership, and this pattern is more pronounced among funds conducting intensive liquidity management. Causal evidence is provided by exploiting the U.S. Securities and Exchange Commission’s 2017 Liquidity Risk Management Rule. Evidence also suggests that the COVID-19 Treasury market turmoil was attributed to intensified liquidity management, an unintended consequence of the 2017 Liquidity Risk Management Rule. (JEL G01, G12, G14, G23)

Abstract 4119250: Partial versus Full ECMO Support in Combined Cardiogenic and Septic Shock – ELSO Registry Analysis

Background: There remains paucity of data on patient outcomes with combined cardiogenic and septic shock requiring veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support. While guidelines exist on target VA-ECMO flow in cardiogenic shock patients, optimal (partial versus full) flow in combined shock remains largely unknown. Methods: We queried the Extracorporeal Life Support Organization registry to identify patients in combined cardiogenic and septic shock supported with VA-ECMO between 2017 and 2022. Patients were categorized into either partial or full ECMO support based on ECMO flow at 24 hours indexed to body surface area. Partial support was defined as < 2.2 liters/m2 while full support was ≥2.2 liters/m2. Patients with other forms of mechanical circulatory support, VA-ECMO as bridge to advanced therapies or discharged on VA-ECMO were excluded from the analysis. Primary outcome of interest was survival to discharge. Baseline characteristics including center volumes and Charlson co-morbidity index were compared between survivors and non survivors. Predictors of mortality were identified using multivariable logistical regression model. Results: A total of 452 patients with combined shock supported with VA-ECMO were identified. Overall mortality was 63%. Patients that survived to discharge were younger (46.3 vs 53 years, p < 0.001) and had lower BMI (29.3 vs 31.1, p = 0.041), Charlson co-morbidity index (1.4 vs 2.0, p = 0.01) and rates of pre-ECMO cardiac arrest (28.7% vs 39.4%, p = 0.023). Survivors were also more likely to be at high [> 25 ECMO runs per year] volume centers compared to low [≤ 10 ECMO runs per year] volume centers (62.3% vs 20.4%, p = 0.04). Patients receiving full ECMO support had a higher likelihood of survival to discharge than partial support (42.6% vs 33.8%, p = 0.063), although it did not reach statistical significance. [Table 1] Indexed VA-ECMO flow at 24 hours was also associated with improved outcomes when assessed as continuous variable. [ Figure 1] Advanced age [aOR 1.02, 95% CI 1.01-1.04, p < 0.001], pre-ECMO cardiac arrest [aOR 1.71, 95% CI 1.11-2.65, p = 0.016] and baseline Charlson co-morbidity index [aOR 1.13, 95% CI 1.01-1.28, p = 0.043] were all associated with increased mortality after adjustment for baseline differences. Conclusion: Mortality among patients requiring VA-ECMO for combined cardiogenic and septic shock is high. Full circulatory support may be associated with improved survival in this cohort.

A Model of the C iv λ λ1548, 1550 Doublet Line in T Tauri Stars

The C iv doublet in the UV has long been associated with accretion in T Tauri stars. However, it is still unclear where and how the lines are formed. Here, we present a new C iv line model based on the currently available accretion shock and accretion flow models. We assume axisymmetric, dipolar accretion flows with different energy fluxes and calculate the properties of the accretion shock. We use Cloudy to obtain the carbon level populations and calculate the emerging line profiles assuming a plane-parallel geometry near the shock. Our model generally reproduces the intensities and shapes of the C iv emission lines observed from T Tauri stars. We find that the narrow component is optically thin and originates in the postshock, while the broad component is optically thick and emerges from the preshock. We apply our model to seven T Tauri stars from the Hubble Ultraviolet Legacy Library of Young Stars as Essential Standards Director’s Discretionary program (ULLYSES), for which the consistently determined accretion shock properties are available. We can reproduce the observations of four stars, finding that the accretion flows are carbon-depleted. We also find that the chromospheric emission accounts for less than 10% of the observed C iv line flux in accreting T Tauri stars. This work paves the way toward a better understanding of hot line formation and provides a potential probe of abundances in the inner disk.

Numerical Investigation of Two-Phase Shock Waves in CO2 Flows Using a Modified Hertz–Knudsen Model

Abstract Understanding the complex behavior of two-phase shocks in CO2 flows is essential for a variety of applications, including carbon capture and storage () and transcritical refrigeration cycles. This study presents a comprehensive numerical investigation of two-phase shock waves using the multispecies user-defined real gas model in Ansys Fluent. The simulations are performed for de-Laval nozzles, exploring the two-phase shock features for three-dimensional (3D), two-dimensional (2D), and two-dimensional axisymmetric geometries. The nonequilibrium condensation, subsequent evaporation, and denucleation occurring across the shock are modeled through a set of user-defined scalar transport equations implemented within Ansys Fluent. The two-phase computational fluid dynamics (CFD) simulations are carried out in proximity to the critical point where real gas effects are relevant. The CO2 real gas properties are computed using an in-house Python code and integrated into the solver via user-defined functions as external look-up tables. This study provides valuable insights into the physical processes underlying two-phase shocks in CO2 flows and their sensitivity to geometric variations and thermodynamic conditions. The findings contribute to the development and modification of predictive models and optimized designs for systems involving two-phase CO2 flows. The results highlight the influence of geometry configurations and thermodynamic conditions on shock location and intensity, providing comparisons for shock waves occurring in two-phase flows and supercritical single-phase flows.

Hybrid-Vlasov Modelling of Ion Velocity Distribution Functions Associated with the Kelvin–Helmholtz Instability with a Density and Temperature Asymmetry

The Kelvin–Helmholtz instability (KHI), characterized by vortices forming at a perturbed velocity shear layer, is a prominent candidate mechanism for mass, momentum, and energy transport across boundaries with velocity shear in various space plasma environments. It is of particular interest at the flanks of Earth’s magnetopause, which separates the plasma of the magnetosphere from the adjacent shocked solar wind flow in the magnetosheath. In the present study, we use local hybrid-Vlasov simulations to investigate the ion velocity distribution functions (VDFs) associated with KHI in a magnetopause-like, transverse velocity shear layer setting (magnetic field perpendicular to the shear plane). We look for signatures of ion finite Larmor radius (FLR) effects, which could be utilized in spacecraft measurements to recognize when such effects are active, influencing KHI evolution and driving plasma mixing. We show that when a density/temperature asymmetry exists across the shear layer, FLR effects produce a heat flux along the vortex edges. With a magnitude (≳0.1 mW m−2) that is a significant fraction of the total magnetosheath energy flux, the heat flux provides a distinct signature that could be measured with a single spacecraft. During the late nonlinear stage of KHI, mixed non-Maxwellian ion VDFs are additionally found within the vortices. Our results are also valid in the presence of a small magnetic shear across the magnetopause.

Decomposition of CH3NH2${\rm CH}_3{\rm NH}_2$: Implications for CHx/NHy${\rm CH}_{\rm {\it x}}/{\rm NH}_{\rm {\it y}}$ radical–radical reactions

AbstractExperiments on methylamine () decomposition in shock tubes, flow reactors, and batch reactors have been re‐examined to improve the understanding of hydrocarbon/amine interactions and constrain rate constants for + reactions. In high‐temperature shock tube experiments, the rapid thermal dissociation of provides a fairly clean source of and radicals, allowing an assessment of reactions of with and NH. At the lower temperatures in batch and flow reactors, is mostly consumed by reaction with H to form + ; these results are useful in determining the fate of the radical. Interpretation of these data, along with flow reactor data for the /H system at lower temperature, indicates that at temperatures up to about 1400 K at atmospheric pressure and above 2000 K at 100 atm, the + reaction forms mainly methylamine. At sufficiently high temperature, H‐abstraction to form + NH and addition–elimination to form + H become competitive. The + NH reaction, with a rate constant close to collision frequency, forms + H, also leading into the hydrocarbon amine pool. Thus, methylamine can be expected to be an important intermediate in co‐combustion of natural gas and ammonia, and more work on the chemistry of is desirable.

Low-angular-momentum General Relativistic Magnetohydrodynamic Accretion Flows around Rotating Black Holes with Shocks

We investigate the global structure of the general relativistic magnetohydrodynamic (GRMHD) accretion flows around Kerr black holes containing shock waves, where the disk is threaded by radial and toroidal magnetic fields. We self-consistently solve the GRMHD equations that govern the flow motion inside the disk and for the first time, to our knowledge, we obtain the shock-induced global GRMHD accretion solutions around weakly as well as rapidly rotating black holes for a set of fundamental flow parameters, such as energy ( E ), angular momentum ( L ), radial magnetic flux (Φ), and isorotation parameter (F). We show that shock properties—namely, the shock radius (r sh), compression ratio (R), and shock strength (Ψ)—strongly depend on E , L , Φ, and F. We observe that the shock in the GRMHD flow continues to exist for a wide range of the flow parameters, which allows us to identify the effective domain of the parameter space in the L–E plane where shock solutions are feasible. Moreover, we examine the modification of the shock parameter space and find that it shifts towards the lower-angular-momentum values with increasing Φ and black hole spin (a k). Finally, we compute the critical radial magnetic flux (Φcri) that admits shocks in GRMHD flows and ascertain that Φcri is higher (lower) for a black hole of spin a k = 0.99 (0.0) and vice versa.

Dollar reserves and U.S. yields: Identifying the price impact of official flows

By exploiting changes in the volatility of U.S. Treasury yields and foreign official (FO) flows into U.S. Treasuries after the 2008 Global Financial Crisis, we identify a FO flow shock via heteroskedasticity in a structural VAR. We estimate that a $100B FO flow shock moves 5 and 10-year U.S. yields by about 100 basis points within a month. An event study of the intraday U.S. Treasury yield curve response to Japan’s FX intervention in September 2022 validates our VAR estimates. Our findings imply that a 1% reduction in the Dollar share of China’s reserves could raise long-term U.S. yields by about 20 basis points.

Measurements of no rotational and vibrational temperatures behind a normal shock in hypervelocity flow via absorption spectroscopy

Measurements of no rotational and vibrational temperatures behind a normal shock in hypervelocity flow via absorption spectroscopy

A self-consistent unified solid-multiphase flow shock model under complex thermodynamic states: For the application of mass-loaded single-turn coils

Single-turn coil (STC) is a destructive pulsed magnet aiming at 100–300 T magnetic field. Mass-loading is the method to increase STC magnetic field. In this study, a unified solid-multiphase flow model is proposed to solve the shock contact problem between the conductor and mass-loading material. This model gives the approach to equate the solid to viscid fluid and equate the melted material to solid and derives the constitutive model for the conductor under non-adiabatic state. Especially, the method to calculate non-adiabatic modulus is investigated. The results show that the equivalent viscosity of solid decreases as the strain rate rises. Moreover, the equivalent shear modulus of the melted solid increases as the strain rate rises, and considering this equivalent shear modulus rather than setting it to zero improves the simulation convergence significantly. This model can provide not only theoretical support for the optimal design of destructive pulse magnets but also methods for theoretical modeling of other types of electromagnetic explosion and shock contact experiments under non-adiabatic condition.

At‐the‐market equity offerings and cash flow shortfalls: Evidence from real estate investment trusts

AbstractThis article examines how access to at‐the‐market (ATM) equity offering programs can help mitigate the adverse effect of temporary cash flow shortfalls on firm performance. Using asset‐level exposure to the spread of COVID‐19 as a proxy for a REIT's sensitivity to a future operational cash flow shock, we find that ATM program access reduces the magnitude of the negative performance effect by nearly 70%. We extend our analysis outside of the pandemic period to provide further evidence of the broader importance of ATM program access as an important source of financial flexibility during more general periods of cash flow uncertainty.

Conceptual design methodology and performance evaluation of turbine-based combined cycle inward-turning inlet with twin-design points

Turbine-based combined cycle (TBCC) engines attract intensive attention due to adequate high working efficiency within the full speed range of air-breathing vehicles. Challenges of TBCC engines lie mostly in common-used components in particular the inlet system, which needs to satisfy the mass flow distribution of different sub-engines and to reconcile the performance requirement in the full speed range. In the present work, a new conceptual design methodology of the three-dimensional inward-turning TBCC inlet with twin-design points is proposed according to the basic flow field with double incident shock waves. The shock structures and flow field parameters at the high-speed design point Ma=4 and mass flow distribution at the low-speed design point Ma=3 both can be designed by the basic flow field. On that basis, a typical inlet model is designed and the corresponding aerodynamic performance is evaluated at two design points. Simulation results prove that the shock structure, the mass flow distribution, and the averaged throat parameters of the TBCC inlet are all consistent with the basic flow field with sufficient accuracy at twin-design points, where the maximum relative error is only 6.3%. Meanwhile, the aerodynamic performance of the inlet shows that the inlet has stable and efficient operation characteristics, which fully affirms the feasibility of the design method.

The enigma of the ‘smoker's paradox’: Results from a single-center registry of patients with STEMI undergoing primary percutaneous coronary intervention

BackgroundSmoker's paradox usually refers to the observation of a favorable outcome of smoking patients in acute myocardial infarction. MethodsFrom April 2006 to December 2018 a population of 2456 patients with ST segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (pPCI) were prospectively enrolled in the MATRIX registry. Ischemic time, clinical, demographics, angiographic data, and 1-year follow-up were collected. ResultsAmong 2546 patients admitted with STEMI, 1007 (41 %) were current smokers. Smokers were 10 years younger and had lower crude in-hospital and 1-year mortality (1.5 % vs 6 %, p < 0.0001 and 5 % vs 11 %, p < 0.0001), shorter ischemic time (203 [147–299] vs 220 [154–334] minutes, p = 0.002) and shorter decision time (60 [30–135] vs 70 [36–170] minutes, p = 0.0063). Smoking habit [OR:0.37(95 % CI:0.18–0.75)-p < 0.01], younger age [OR 1.06 (95%CI:1.04–1.09)-p < 0.001] and shorter ischemic time [OR:1.01(95%CI:1.01–1.02)-p < 0.05] were associated to lower in-hospital mortality. Only smoking habit [HR:0.65(95 % CI: 0.44–0.9)–p = 0.03] and younger age [HR:1.08 (95%CI:1.06–1.09)–p < 0.001] were also independently associated to lower all-cause death at 1-year follow-up. After propensity matching, age, cardiogenic shock and TIMI flow <3 were associated with in-hospital mortality, while smoking habit was still associated with reduced mortality. Smoking was also associated with reduced mortality at 1-year follow-up (HR 0.54, 95 % CI [0.37–0.78]; p < 0.001). ConclusionsSmoking patients show better outcome after PCI for STEMI at 1-year follow-up. Although “Smoking paradox” could be explained by younger age of patients, other factors may have a role in the explanation of the phenomenon.

A modified fifth‐order WENO‐Z scheme based on the weights of the reformulated adaptive order WENO scheme

AbstractA modified fifth‐order WENO‐Z scheme is proposed by analogy with the non‐normalized weights of the reformulated fifth‐order adaptive order (AO) WENO scheme. We show that if the original fifth‐order WENO‐AO scheme is rewritten as the form of the conventional WENO combination, the resulting non‐normalized weights can be divided into three parts: a constant one term, a local stencil smoothness measure term and a global stencil smoothness measure term. In order to make use of the latter two terms for constructing a modified WENO‐Z scheme with enhanced performance, we change the form of the third term and introduce an adaptive scaling factor to adjust the contributions from the second and third terms. Numerical examples show that the modified fifth‐order WENO‐Z scheme has the advantage of high resolution in smooth regions and sharp capturing of discontinuities, and it can obtain evidently better results for shocked flows with small‐scale structures compared with the recently developed WENO‐Z+ and WENO‐Z+M schemes.