Reverse Stress Research Articles

Finite element analyses of the effect of weld overlay sizing on residual stresses of the dissimilar metal weld in PWRs

Dissimilar metal welds are commonly used in various types of reactors to connect low alloy steel nozzles and austenitic stainless steel piping systems. To mitigate the degradation of stainless steel pipe welds that are affected by intergranular stress corrosion cracking in BWRs, weld overlays have been implemented to provide the structural reinforcement. They have also been applied to repair dissimilar metal welds at nozzles in BWRs and PWRs. A weld overlay can favorable reverse residual stresses from tensile to compressive around interior of the susceptible materials. The ASME Code Case N-504 series suggest that the evaluation of repaired welds should consider residual stresses that are generated by the weld overlay with other applied loads on the system. This study considers a dissimilar metal weld that joins the low alloy steel nozzle to the stainless steel safe end in a typical PWR, and is to calculate the post-overlay residual stress states using ANSYS finite element analysis software. Based on the stress report and site survey of the hot leg nozzle, models for analyzing residual stresses were developed on various assumptions. Computational results demonstrate that the weld overlay process probably provides compressive distributions of axial and hoop residual stresses at the inside surface of the dissimilar metal weld. The residual stress distributions that are induced by weld overlays of various sizes are compared to determine the effect of weld overlay sizing on the residual stresses in the original weld. The comparison reveals that weld overlay length has a greater effect on residual stresses than weld overlay thickness. As the applied overlay length increases, the compressive residual stresses increase markedly. Each nozzle/safe end design is somewhat unique; using a feasible weld overlay dimension in consideration of technical and economic is necessary. This investigation has provided a reference for optimizing the weld overlay design of dissimilar metal welds in PWRs.

Temperature stress and fertility reversibility in wild abortive CMS lines of rice for quality hybrid seed production

CMS lines are highly sensitive to temperature change for the sterility status. Determination of critical temperature for sterility breakdown in wild abortive cytoplasmic male sterile (WA-CMS) lines under field condition is essential for efficient seed production planning. CMS lines IR58025A and IR68897A were grown at different dates of sowing to give exposure to a series of temperature regime and day length at natural field condition. At panicle initiation stages, temperatures below 28.5 °C, the CMS lines were sterile and at temperatures below 30 °C, the lines became partially sterile. Above 30 °C, the CMS line reverted to fertile. The highest pollen sterility was recorded (98.3%) during the long day condition while the lowest was recorded (43.5%) during the short day condition indicating the effect of both temperature and day-length on break down of sterility. Differential expression of floral characters like panicle exertion and stigma was found with variation in temperature. This simple field-driven technique can be successfully employed to work out the functional temperature for fertility reversibility which is of utmost importance for planning seed production and maintenance of genetic purity of the hybrids. The technique will aid in designing seed production planning for hybrid rice locally in any rice-growing area of the world in the present scenario of restrictions in export and import of agricultural commodities.

Managing bank risk through the crisis perspective from Malaysia

This paper considers the practical implications of the COVID-19 crisis for risk management in a bank in Malaysia and goes on to draw more general conclusions. It is suggested that standard strategic and credit risk-management practices will need to be taken to the next level in order for banks to better prepare for 2021. Recommendations have been given for improving stress testing and credit risk assessment so as to provide enhanced information on the basis of which difficult decisions can be made. In particular, it is suggested that greater use of reverse stress testing will be beneficial. This use should be coupled with more sophisticated relationships between macroeconomic scenarios and potential credit losses, which will give the bank management a much improved control over uncertainties in the macroeconomy. It is also suggested that banks apply a similar, more formalised (stress testing) approach to credit risk assessment of their larger customers so that a realistic assessment of their repayment ability can be made. Finally, some hard thinking about the future shape of banking needs to be carried out and positions taken in terms of technology, staffing levels, office space and product offerings.

Structural Controls on Alteration Stages at the Chuquicamata Copper-Molybdenum Deposit, Northern Chile

AbstractAll existing bench and tunnel vein and fault structural data with identified mineral infill, acquired in Chuquicamata, were georeferenced, digitized, and, according to their mineralogy, assigned to one or more of the major alteration events developed between 35 and 31 Ma. Veins and faults were separated into two main stages: (1) the late magmatic and potassic stage that comprises the background potassic and the propylitic alteration and (2) the hydrothermal stage composed by early (intense potassic), main (principal and late sericite; hydrothermal stages H1 through H4), and late (advanced argillic alteration) hydrothermal events. The spatial distribution of the propylitic to late-hydrothermal events that plotted within the major fault framework indicate these had either permeable or impermeable (±barrier) behavior through time. The area of the deposit was divided into 600 square grids measuring 100 × 100 m, and a stress orientation analysis was carried out for every propylitic to late-hydrothermal alteration event. The analysis indicates that the local principal horizontal stress (σH) trajectories are nonlinear and noncoaxial through the successive alteration events, differing from the previous and following stages, and in the majority of cases do not coincide with the approximate east-northeast orientation of the inferred tectonic far-field stress orientation. The differences between the stress trajectories, away from the far-field stress orientation throughout the evolution of the system, are considered to be principally related to the dynamic variations experienced by the stress components, such as thermal-magmatic stresses linked to temperature fluctuations due to cooling or heating by progressive igneous/hydrothermal activity and/or elastic, overburden-related stresses associated with reaccommodations developed during uplift and erosion. The estimated stresses resulting after erosional unroofing and decreasing temperature indicate that the maximum horizontal stress varied as the system evolved from the commonly accepted depth of emplacement of ~6 km. During the late magmatic, background potassic, and intense potassic stages, the calculated differential stress was contractional, decreasing to an isotropic state at the contraction-extension stress reversal that hosted the main hydrothermal H1 through H3 events, to finally become extensional at the shallow late-hydrothermal event. The most significant mineralization occurred at the time of stress reversal, coincidental with the sericite and quartz-sericite events (H1-H4), associated with hydrothermal fluid accumulation, overpressuring, and multiple-orientated hydraulic fracture development.The Chuquicamata study suggests that the local stress control involved in the emplacement of porphyry copper systems is fundamentally related to variable and progressive heat energy release, associated with igneous and hydrothermal activity, and to the elastic stresses derived from uplift and unloading, rather than to a constant far-field tectonic stress. The continuous local stress fluctuations led to bulk stress readjustments and cyclical stress-fluid interactions for local fault reactivation, damage zone modification, brecciation, permeability creation/destruction, and fluid focusing, as well as the discharge of hydrothermal fluids throughout the evolution of the system.

Micellar TIA1 with folded RNA binding domains as a model for reversible stress granule formation

TIA1, a protein critical for eukaryotic stress response and stress granule formation, is structurally characterized in full-length form. TIA1 contains three RNA recognition motifs (RRMs) and a C-terminal low-complexity domain, sometimes referred to as a "prion-related domain" or associated with amyloid formation. Under mild conditions, full-length (fl) mouse TIA1 spontaneously oligomerizes to form a metastable colloid-like suspension. RRM2 and RRM3, known to be critical for function, are folded similarly in excised domains and this oligomeric form of apo fl TIA1, based on NMR chemical shifts. By contrast, the termini were not detected by NMR and are unlikely to be amyloid-like. We were able to assign the NMR shifts with the aid of previously assigned solution-state shifts for the RRM2,3 isolated domains and homology modeling. We present a micellar model of fl TIA1 wherein RRM2 and RRM3 are colocalized, ordered, hydrated, and available for nucleotide binding. At the same time, the termini are disordered and phase separated, reminiscent of stress granule substructure or nanoscale liquid droplets.

Analysis on degradation mechanisms of normally-off p-GaN gate AlGaN/GaN high-electron mobility transistor* *Project supported by the Equipment Developing Advanced Research Program of China (Grant No. 6140A24030107).

The degradation mechanisms of enhancement-mode p-GaN gate AlGaN/GaN high-electron mobility transistor was analyzed extensively, by means of drain voltage stress and gate bias stress. The results indicate that: (i) High constant drain voltage stress has only a negligible impact on the device electrical parameters, with a slightly first increase and then decrease in output current; (ii) A negative shift of threshold voltage and increased output current were observed in the device subjected to forward gate bias stress, which is mainly ascribed to the hole-trapping induced by high electric field across the p-GaN/AlGaN interface; (iii) The analyzed device showed an excellent behavior at reverse gate bias stress, with almost unaltered threshold voltage, output current, and gate leakage current, exhibiting a large gate swing in the negative direction. The results are meaningful and valuable in directing the process optimization towards a high voltage and high reliable enhanced AlGaN/GaN high-electron mobility transistor.

Quantification of principal horizontal stresses inside a tunnel: An application of Fracture induced Electromagnetic Radiation (FEMR) technique in the Darjeeling-Sikkim Himalayas

Characterization of recent stresses, delineation of the locations of active faults/landslide prone slip planes and forecasting earthquakes are some of the emerging applications of the Fracture Induced Electromagnetic Radiation (FEMR) technique. It is believed that such radiation is polarized along the direction of maximum compression and proportional to the maximum applied shear stress. In this paper, we have demonstrated the use of the FEMR technique to calculate the magnitude and directions of principal horizontal stresses inside a tunnel of ~240 m length over a hilly road between Jorethang and Mayong near the village of Miyong in Sikkim, India by taking 11 “cross-sectional” measurements using a portable FEMR recording device called ANGEL-M. Although a reverse stress regime is obvious and established over the Himalayas, the results show a normal stress regime prevailing over this shallow, near-surface region of the tunnel and the direction of maximum shear stress changes along the tunnel length. The results were explained with the aid of a simple clay analogue model where normal reactivation of a thrust plane with changing dips was simulated. With this communication, we hope to encourage scientists and engineers to deploy the FEMR technique which is lesser known but quicker, non-destructive, cheaper, and more accessible than conventional methods in evaluating tunnel safety by calculating shallow stresses locally modified inside a tunnel.

Improved the C–V Curve Shift, Trap State Responsiveness, and Dynamic R ON of SBDs by the Composite 2-D–3-D Channel Heterostructure Under the OFF-State Stress

In this article, the C-V curve shift, trap densities responsiveness,and dynamic R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> of AlGaN/GaN/GaN:C (SH:C) and AlGaN/GaN/graded-AlGaN:Si/GaN:C (DH:Si/C) heterostructure Schottky barrier diodes (SBDs) have been systematically analyzed. Due to additional 3-D electrons in graded-AlGaN:Si layer, the composite 2-D-3-D channel of DH:Si/C has a higher carrier concentration. Reducing the OFF-state electric field strength through AlGaN:Si insert layer, a smaller positive shift of C-V curve is achieved under OFF-state stress. Due to the charge shielding effect of AlGaN:Si insert layer, trapping/detrapping effects in GaN:C buffer under the OFF-state stress are well suppressed. Compared with SH:C heterostructure, the trap density responsiveness of DH:Si/C heterostructure under OFF-state stress is significantly reduced. At the same time, trap density responsiveness of the upper channel is immune to OFF-state electric stress time. In addition, the proposed SBDs show lower ON-resistance with on reverse bias stress and better dynamic performance with on reverse stress time.

Piecewise Linear Plastic Potentials as a Tool for Calculating Plane Transient Temperature Stresses

A numerical-analytical solution of a one-dimensional problem of the theory of temperature stresses on the evolution of plane stress states under conditions of heating and subsequent cooling of a round plate made of an elastoplastic material is constructed. The plate is heated in such a way that the level of the bell-shaped temperature distribution increases in proportion to the time up to the set maximum value. After that, the heating source is removed and then cooling occurs in natural conditions. It is shown that following the conditions of piecewise-linear plastic potentials at any calculated time of the deformation process, integration of the equilibrium equation establishes dependences connecting reversible and irreversible deformations and stresses with the temperature distribution. The yield point is assumed to be quadratically dependent on temperature; elastic moduli, specific heat and thermal expansion coefficient are considered constant. It was found that the problem under consideration in the framework of the Tresca-Saint Venant plastic potential has no solution, but it can be solved in the framework of the Ishlinsky – Ivlev plastic potential.

Gate threshold voltage instability and on-resistance degradation under reverse current conduction stress on E-mode GaN-HEMTs

This paper investigates device characteristic shift of E-mode GaN-HEMTs, especially focusing on stress effects under reverse current conduction. Experimental results exhibit that power losses of reverse current conduction is relatively higher than that of forward current conduction. After forward and reverse stress, gate threshold voltages were shifted to negative. On the other hand, on-resistances were increased depending on time duration in the both stress conditions. From our analysis, the electrical parameters shift could be caused by the gate contact and gate electrode degradation.

Hydrogen peroxide potentiates defense system in presence of sulfur to protect chloroplast damage and photosynthesis of wheat under drought stress.

The involvement of hydrogen peroxide (H2 O2 ) combined with sulfur (S) was studied in the protection of the photosynthetic performance of wheat (Triticum aestivum L.) under drought stress. The mechanisms of S-assimilation, the activity of antioxidants, glucose sensitivity, water and osmotic relations and abscisic acid (ABA) content were the focus. The combined application of 50 μM H2 O2 and 100 mg S kg-1 soil (sulfur) resulted in a marked increase in S-assimilation and activity of antioxidant enzymes, with decreased glucose sensitivity and ABA content causing improvement in the structure and function of the photosynthetic apparatus under drought stress. The photosynthetic performance, pigment system (PS) II activity, and growth were improved conspicuously by H2 O2 in the presence of S, as H2 O2 induced S-assimilation capacity, the activity of antioxidant enzymes, and GSH synthesis under drought stress. Our study shows that H2 O2 is more effective in the reversal of drought stress in the presence of S through its influence on S-assimilation, glucose sensitivity, and antioxidant system. These results provide evidence for the effectiveness of H2 O2 in improving photosynthesis under drought stress in the presence of S.

Digitally controlled GaN‐based MHz active clamp flyback converter with dynamic dead time optimisation for AC–DC adapter

The active clamp flyback (ACF) converter utilising gallium nitride (GaN) devices with high-switching frequency and high efficiency is impressive in system miniaturisation for AC–DC adapters. Owing to poor reverse conduction of GaN devices, the improper dead time between two switches can cause large power consumption in high frequency. This study proposes a dynamic dead time optimisation technique for GaNs ideal zero-voltage switching (ZVS) to address the issue. It adjusts the clamp switch on time to avoid large reverse conduction voltage stress on the main switch in different loads conditions. In addition, a new control scheme for clamp switch is introduced for enhancing efficiency in light to medium load. These techniques are experimentally verified on a 45 W (20 V/2.25 A) prototype of an ACF converter with a field-programmable gate array. The controller enables the system to operate at 1 MHz and dynamically modulates the dead-time under universal input and full load. With the light load ZVS control scheme, the system can achieve a maximum efficiency of 94.12 and 80.23% in the worst case. The prototyped converter can achieve power density (exclude case and controller) of 18 W/in3.

Repeated exposure to transient obstructive sleep apnea–related conditions causes an atrial fibrillation substrate in a chronic rat model

High night-to-night variability in obstructive sleep apnea (OSA) is associated with atrial fibrillation (AF). Obstructive apneas are characterized by intermittent deoxygenation-reoxygenation and intrathoracic pressure swings during ineffective inspiration against occluded upper airways. We elucidated the effect of repeated exposure to transient OSA conditions simulated by intermittent negative upper airway pressure (INAP) on the development of an AF substrate. INAP (48 events/4 h; apnea-hypopnea index 12 events/h) was applied in sedated spontaneously breathing rats (2% isoflurane) to simulate mild-to-moderate OSA. Rats without INAP served as a control group (CTR). In an acute test series (ATS), rats were either killed immediately (n = 9 per group) or after 24 hours of recovery (ATS-REC: n = 5 per group). To simulate high night-to-night variability in OSA, INAP applications (n = 10; 24 events/4 h; apnea-hypopnea index 6/h) were repeated every second day for 3 weeks in a chronic test series (CTS). INAP increased atrial oxidative stress acutely, represented in decreases of reduced to oxidized glutathione ratio (ATS: INAP: 0.33 ± 0.05 vs CTR: 1 ± 0.26; P = .016), which was reversible after 24 hours (ATS-REC: INAP vs CTR; P = .274). Although atrial oxidative stress did not accumulate in the CTS, atrial histological analysis revealed increased cardiomyocyte diameters, reduced connexin 43 expression, and increased interstitial fibrosis formation (CTS: INAP 7.0% ± 0.5% vs CTR 5.1% ± 0.3%; P = .013), which were associated with longer inducible AF episodes (CTS: INAP: 11.65 ± 4.43 seconds vs CTR: 0.7 ± 0.33 seconds; P = .033). Acute simulation of OSA was associated with reversible atrial oxidative stress. Cumulative exposure to these transient OSA-related conditions resulted in AF substrates and was associated with increased AF susceptibility. Mild-to-moderate OSA with high night-to-night variability may deserve intensive management to prevent atrial substrate development.

Three-Dimensional Geomechanical Modeling and Analysis of Refracturing and “Frac-Hits” in Unconventional Reservoirs

Field experience has demonstrated that infill well fractures tend to propagate towards the primary well, resulting in well-to-well interference, or so-called “frac-hits”. Frac-hits are a major concern in horizontal well refracturing because they adversely affect the productivity of both wells. This paper provides a 3D geomechanical study of the problem for the first time in order to better understand frac-hits in horizontal well refracturing and its mitigating solutions. To our knowledge, this is the only refracturing study focused on fracture mechanics and within the context of coupled proroelasticity using a single model. The modeling is based on the fully coupled 3D model, GeoFrac-3D, which is capable of simulating multistage fracturing of multiple horizontal wells. The model couples pore pressure to stresses, and makes it possible to create dynamic models of fracture propagation. The modeling results show that production from production well fractures leads to a nonuniform reduction of the reservoir pore pressure around the production well and in between fractures, leading to an anisotropic decrease of the total stress, potentially resulting in stress reorientation and/or reversal. The decrease in the total stress components in the vicinity of the production fractures creates an attraction zone for infill well hydraulic fractures. The infill well fractures tend to grow asymmetrically towards the lower stress zone. The risk of frac-hits and the impact on the “parent” and “infill” well production vary according to the reservoir stress regime, in situ stress anisotropy, and production time. By optimizing well and fracture spacing, fracturing fluid viscosity, and the timing of refracturing job, frac-hit problems can be minimized. The simulation results demonstrate that the risks of frac-hits can be potentially mitigated by repressurization of the production well fractures before fracturing the infill well.

Assessment of small-scale deformation characteristics and stress-strain behavior of NiTi based shape memory alloy using nanoindentation

The study is focused to understand the micro-mechanisms that govern the deformation behavior of a Ni-rich NiTi alloy at the sub-micron scale. This alloy undergoes reversible stress induced martensitic transformation leading to pseudoelasticity. Correspondingly, significant strain recoverability is noted. In this investigation, nanoindentation is utilized as the primary experimental tool. Various parameters including the indenter tip configuration, size and applied load levels are varied systematically. It is observed that compared to the most commonly used sharp Berkovich indenter tip, blunt spherical tip imposes reduced amount of strain and strain-gradient within the indentation volume. This opens up the window for systematically varying the sequential deformation modes in NiTi. Further in-depth analysis revealed that optimum combination of indenter tip configuration, size and applied load level is prerequisite to appreciate the pseudoelastic mechanism in NiTi. Most importantly, a tailored and simplified protocol is formulated for converting nanoindentation load-displacement response to corresponding indentation-stress-strain behavior for pseudoelastic alloy. These indentation-stress-strain curves featuring the signature deformation characteristics of NiTi alloy are realized without utilizing any specialized experimental modes. In a nutshell, this study highlights the importance of choosing adequate nanoindentation parameters for assessing the functional characteristics of pseudoelastic NiTi system at sub-micron scale. Accordingly, overall localized deformation behavior of this unique alloy is investigated.

Relationship between the matric suction and the shear strength in unsaturated soil

To understand the shear strength properties for unsaturated soil with different matric suction values, a modified triaxial test device was used. The matric suction is considered an important contributor to unsaturated shear strength properties. In this research, the modified triaxial testing machine is used to control the matric suction and to avoid the turbulence and bubbles during test, which keep the matric suction in positive value. The range of the matric suction used is from (0–100) kPa and the it was applied by increments of (10) kPa in each time. It was concluded that the relationship between the shear strength and the matric suction is divided into two parts, the first part is linear and the second is non-linear. The point between the two parts represents a point of reversal stress the two parts which is also considered as the peak stress point. The matric suction increases the soil elasticity, and all the stress variables also increase the angle of the internal friction between the soil particles. The maximum shear stress occurs at a larger matric suction with increase of confining pressure.

Oleanolic Acid Decreases IL-1β-Induced Activation of Fibroblast-Like Synoviocytes via the SIRT3-NF-κB Axis in Osteoarthritis.

Synovial inflammation is a major pathological feature of osteoarthritis (OA), which is a chronic degenerative joint disease. Fibroblast-like synoviocytes (FLS), localized in the synovial membrane, are specialized secretory cells. During OA synovitis, FLS produce chemokines and cytokines that stimulate chondrocytes to secrete inflammatory cytokines and activate matrix metalloproteinases (MMPs) in FLS. Recent studies have demonstrated that sirtuin 3 (SIRT3) performs as a key regulator in maintaining mitochondrial homeostasis in OA. This study aims at ascertaining whether SIRT3 is involved in OA synovitis. The overexpression (OE) and knockdown (KD) of SIRT3 are established by short hairpin RNA (shRNA) and recombinant plasmid in human FLS. The anti-inflammatory effect of SIRT3 underlying in oleanolic acid- (OLA-) prevented interleukin-1β- (IL-1β-) induced FLS dysfunction is then evaluated in vitro. Additionally, the molecular mechanisms of SIRT3 are assessed, and the interaction between SIRT3 and NF-κB is investigated. The data suggested that SIRT3 can be detected in human synovial tissues during OA, and OLA could elevate SIRT3 expression. OE-SIRT3 and OLA exhibited equal authenticity to repress inflammation and reverse oxidative stress changes in IL-1β-induced human FLS dysfunction. KD-SIRT3 was found to exacerbate inflammation and oxidative stress changes in human FLS. Furthermore, it was found that SIRT3 could directly bind with NF-κB, resulting in the suppression of NF-κB activation induced by IL-1β in human FLS, which then repressed synovial inflammation in OA. In general, the activation of SIRT3 by OLA inhibited synovial inflammation by suppressing the NF-κB signal pathway in FLS, and this suggested that SIRT3 is a potential target for OA synovitis therapy.

Verification of Fracture Reorientation and Analysis of Influence Factors in Multiple Fracturing Treatment

A fracture will be initiated and propagated along the direction of maximum horizontal stress in fracturing treatment; however, in refracturing stimulation, the new fracture may be initiated and propagated along a different direction from the initial one. This is defined as a fracture reorientation. It is difficult to predict fracture reorientation due to the variation of formation properties after long-term production. To verify the existence of fracture reorientation and analyze its influencing factors in multiple fracturing treatment, experimental and numerical simulations are presented in this paper. Firstly, multiple fracturing stimulation is carried out with a self-assembled large true triaxial apparatus, and the fracture reorientation is successfully induced by changing the injection pressure and initial stresses in multiple fracturing processes. Then, numerical coupled hydromechanical modeling of the actual field production and injection well pattern is performed. In particular, the stress reversal region, which indicates the distance of fracture reorientation, and the factors that influence the reorientation are analyzed. The laboratory experiment and numerical simulation results show that the fracture reoriented angle obtained can be perpendicular to the initial fracture. Stress field and formation pressure are the two main factors that influence the fracture reorientation. With higher pressure differences and lower initial horizontal stress differences, the area in which it is possible to initiate reoriented fracture will be larger. The fractures of wells in the early production stage are hard to reorient due to the high formation and borehole pressure difference, and the fracture reorientation area will be expanded until the pressure difference is low to a certain value. This research result can guide oilfield stimulation treatments.

Reverse Stress Testing: Scenario Design for Macroprudential Stress Tests

We propose a systematic algorithmic reverse-stress testing methodology to create ``worst scenarios for regulatory stress tests by accounting for losses that arise from distressed portfolio liquidations. First, we derive the optimal bank response for any given shock. Then, we introduce an algorithm which systematically generates scenarios that exploit the key vulnerabilities in banks' portfolio holdings and thus maximize contagion despite banks' optimal response to the shock. We apply our methodology to data of the 2016 European Banking Authority (EBA) stress test, and design worst case scenarios for the portfolio holdings of European banks at the time. Using spectral clustering techniques, we group 10'000 worst-case scenarios into twelve geographically concentrated families. Our results show that even though there is a wide range of different scenarios within these twelve families, each cluster tends to affect the same banks. An ``Anna Karenina principle of stress testing emerges: Not all stressful scenarios are alike, but every stressful scenario stresses the same banks. These findings suggest that the precise specification of a scenario is not of primal importance as long as the most vulnerable banks are targeted and sufficiently stressed. Finally, our methodology can be used to uncover the weakest links in the financial system and thereby focus supervisory attention on these, thus building a bridge between macro-prudential and micro-prudential stress tests.

Low Mach number fluctuating hydrodynamics model for ionic liquids

We present a new mesoscale model for ionic liquids based on a low Mach number fluctuating hydrodynamics formulation for multicomponent charged species. The low Mach number approach eliminates sound waves from the fully compressible equations leading to a computationally efficient incompressible formulation. The model uses a Gibbs free energy functional that includes enthalpy of mixing, interfacial energy, and electrostatic contributions. These lead to a new fourth-order term in the mass equations and a reversible stress in the momentum equations. We calibrate our model using parameters for [DMPI+][F6P-], an extensively-studied room temperature ionic liquid (RTIL), and numerically demonstrate the formation of mesoscopic structuring at equilibrium in two and three dimensions. In simulations with electrode boundaries the measured double layer capacitance decreases with voltage, in agreement with theoretical predictions and experimental measurements for RTILs. Finally, we present a shear electroosmosis example to demonstrate that the methodology can be used to model electrokinetic flows.