Injection Phase Research Articles

Feasibility of ultra-low volume contrast pulmonary arterial injection protocol for CTA in TAVI candidates with severe renal failure

Abstract Introduction Computer tomography angiography (CTA) has an important role in patient screening before TAVI. The high volumes of iodinated contrast media (CM) injected during the examination represents the main limitation of CTA with a dose-dependent association with contrast-induced nephropathy. Purpose Show the feasibility of an ultra-low-dose CM pulmonary arterial injection protocol for CTA in TAVI candidates in high risk patients with severe renal failure. Methods In our retrospective study seventy-seven (77) patients with CKD on stage 3b or worse (eGFR ≤ 45/min/1.73 m2) underwent pre-procedural CTA for TAVI-planning with a pulmonary arterial administration of CM. All CTA examinations were performed using a Dual Source 256-slice CT system. All enhanced CT acquisitions were performed using our dedicated biphasic injection protocol composed of two connected phases of contrast medium injection using different amount of CM (8, 10, 15 and 20 ml) according to BMI (<22 kg/m2; 22-24 kg/m2; 24-28 kg/m2; >28 kg/m2). The CM was administered directly into the pulmonary artery in all patients. For each examination was measured Intraluminal attenuation at thoraco-abdominal aorta and along the ilio-femoral vessels using the ROI (mean SD in HU) as objective image parameters (Picture 1). Serum creatinine and the eGFR were recorded pre-TAVI CT scan and after the procedures as reference of CM to renal function. Results CTA was successfully performed in all patients. Mean creatinine was 2.25 ± 0,76 mg/dL and mean GFR was 26.5± 8.1 mL/min/m2. Mean vessel attenuation was 352±164 HU at the aortic annulus, 238.1 ± 141,3 HU in the aortic arch and 266±168 in the iliac arteries (Picture 2). The mean image noise was 28.2 ± 7 HU in the aortic annulus, 24.4 ± 10,9 in the right external iliac artery, and 25. ± 12,8 HU in the left external iliac artery. After CTA examination, a total of 74 patients (96%) underwent TAVI. Mean CM dose administered during TAVI procedure was 150,6 ± 85,8. Three patients (3.9%) were abolished for TAVI. Postprocedural settings complications were recorded. A total of 31 patients (41%) had grade 1 paravalvular regurgitation, 10 patients (14%) grade 2. No cases of valve embolization or anulus rupture occured. No major vascular complications occured. No significant differences between creatine and eGFR pre and post procedures (p<0,001). Conclusions The use of an ultra-low-dose CM pulmonary arterial injection protocol for CTA in TAVI candidates does not affect the renal function and procedural success rate is high and the clinical outcomes after TAVI is satisfactory according to the litterature.

Chemical enhanced oil recovery using carbonized ZIF-67 MOFs and sulfonated copolymers at high reservoir temperatures

Traditional nanoparticle and polymer-based enhanced oil recovery methods face challenges such as nanoparticle agglomeration and polymer adsorption, particularly at elevated reservoir temperatures. This study introduces hybrid polymeric nanofluids, combining carbonized Zeolitic Imidazolate Framework-67 (ZIF-67) with sulfonated copolymers to address these issues. Viscosity tests were conducted at 25 °C, 50 °C, 75 °C, and 90 °C, revealing a 39.67 % increase in viscosity at 90 °C, attributed to electrostatic and hydrogen bond interactions. For subsequent analyses—stability, adsorption, and core flooding—75 °C was selected as the representative high reservoir temperature. Stability assessments, confirmed via UV–Vis spectroscopy, demonstrated nanofluid durability over at least seven days. Carbonized ZIF-67 reduced polymer adsorption on rock surfaces, enhancing oil recovery and reducing environmental impact. Dynamic core flooding experiments showed a 45.8 % improvement in oil recovery by the hybrid nanofluid on carbonate rock samples. The hybrid nanofluid increased RF and RRF, improving the mobility ratio and redirecting flow to lower-permeability zones, reducing unswept oil and enhancing macroscopic sweep efficiency. Winsor Type III emulsification during the post-flooding phase of polymer-nanoparticle injection significantly improved trapped oil mobilization. Reduced contact angles from 170° to 100° altered the wettability, enhancing oil recovery. Carbonized ZIF-67 nanoparticles increased viscous forces, reduced capillary forces, and minimized polymer adsorption. The polymeric nanofluid achieved a capillary number of 1.0 × 10−3, two orders higher than that of polymer alone, resulting in superior performance. Injectivity optimization showed shear rates of 15.9 s−1 in 1700 mD cores and 79.8 s−1 in 80 mD cores, causing pressure drops of 15 psi and 1200 psi, respectively. This highlights injectivity challenges in 80 mD cores, while cores ≥ 290 mD are ideal for our polymer-nanoparticle hybrid applications.

8008 Insulin-like Growth Factor-1 (IGF-1) Level Fluctuations and Patient Reported Outcomes (PROMS) During Treatment with Long-acting Somatostatin Receptor Ligands (SRLs) for Acromegaly: a Prospective Study

Abstract Disclosure: I. Remba-Shapiro: None. J.R. Schweizer: None. K.J. Liebert: Consulting Fee; Self; Crinetics, Recordati Rare Diseases, Novo Nordisk. K. Schilbach: None. M. Adams: Consulting Fee; Self; Chiesi. N.A. Tritos: None. M. Bidlingmaier: Consulting Fee; Self; Ipsen, Ionis Pharmaceuticals Inc., Novartis Pharmaceuticals, Novo Nordisk, Pfizer, Inc., Roche Pharmaceuticals. L.B. Nachtigall: Consulting Fee; Self; Crinetics. Grant Recipient; Self; Amryt, Recordati Rare Diseases. Background: SRLs are the most used medical therapy for acromegaly. Some patients report symptoms of acromegaly towards the end of the injection cycle even when IGF-1 levels are controlled. IGF-1 fluctuations within an injection cycle have been observed. In this study we investigated the variability of biochemical markers and PROMS in patients receiving long-acting SRLs. Methods: Subjects with acromegaly controlled with monthly lanreotide depot or octreotide LAR were recruited. Blood samples at 1 and 4 weeks after SLR injection were collected in 2 consecutive cycles. Clinical characteristics were evaluated. Quality of life (QoL) surveys included: Acromegaly Quality of Life Questionnaire (AcroQoL) (higher scores = better QoL) and Patient Assessed Acromegaly Symptom Questionnaire (PASQ) (higher scores = worse QoL). Week 1 vs. week 4 values were compared. Quest Diagnostics LC-MS assay was used to measure IGF-1. Coefficient of variation (CV = (IGF-1 SD)/(IGF-1 mean)%) of IGF-1 was calculated. Values ≤5% were interpreted as being a consequence of assay variability. Variables are presented as mean (SD) and compared using t-test; p <0.05 was considered significant. Results: Patients (6 women, 4 men) had a mean age of 56.1 (15.4) years. Eight underwent TSS. One had diabetes mellitus, 3 had hypertension. Mean IGF-1 index (IGF-1 x upper limit of normal) at screening was 0.63 (0.23). BMI was 27.7 (5.8) kg/m2. IGF-1 index at week 1 was 0.57 [0.16] vs. 0.61 [0.23] at week 4, p=0.271. Insulin levels were lower in week 1 vs. week 4 (7.3 [4.4] vs. 9.7 [6.0]mIU/mL p=0.041). There were no significant differences in GH, glucose, weight, blood pressure and ring size in week 1 vs. week 4. PASQ varied significantly within the injection cycle with higher scores in week 4 (18.1 [10.8]) compared to week 2 (16.1 [10.4] p=0.032) and week 3 (14.2 [8.8] p= 0.002). ACROQoL scores did not differ by injection phase. IGF-1 increased more than assay CV from week 1 to week 4 in 8/20 (40%) determinations. An ROC curve identified an IGF-1 index cutoff of 0.57 at week 4 (AUC: 0.812, p=0.021) as a predictor of IGF-1 index increase within the injection cycle (CV > 5%): sensitivity 88%, specificity 75%. Five patients had IGF-1 index > 0.57 at week 4 during both cycles (range 0.60-1.2). In this group, mean IGF-1 index was higher at week 4 vs. week 1 (0.77 [0.21] vs. 0.66 [0.14] p=0.026). The 5 patients with IGF-1 index < 0.57 at week 4 had no difference in IGF-1 index between week 4 and week 1 (0.48 [0.14] vs. 0.44 [0.09] p=0.144). Conclusions: This prospective study of patients with acromegaly controlled with long-acting SRLs demonstrates injection phase variability in self-reported symptoms by PASQ. An IGF-1 index > 0.57 at the end of the cycle may warrant injection phase-dependent monitoring. Larger studies to confirm the IGF-1 cutoff above which patients should be monitored in a cycle-dependent manner will allow an individualized approach to optimize management. Presentation: 6/2/2024

Effect of ignition timing and hydrogen injection phase on HDI engine combustion and NOx emissions

ABSTRACT In order to improve the ITE and reduce NOx emissions in direct-injected hydrogen (HDI) engines under at medium and high loads, the effects of IT and hydrogen injection phase on the combustion and NOx emission characteristics of the HDI engine at high rpm and medium load were investigated numerically. The base engine is a four-cylinder turbocharged direct-injected gasoline (GDI) engine, which is modified into a HDI engine with direct-injected hydrogen fuel. The simulation is performed using GT-Power software. The operating condition of HDI engine is set to 5500 rpm and 50% load. Firstly, IT is optimized, and then based on the IT optimization results, the hydrogen injection phase is optimized. The results show that as the IT is advanced, the maximum pressure rise rate (MPRR) shows a gradual increasing trend, while the combustion intensity and the indicated thermal efficiency (ITE) increases firstly and then decreases, and the former reaches a maximum value at 25° CA BTDC, while the latter reaches a maximum value of 40.5% at 18°CA BTDC. In addition, the nitrogen oxide (NOx) emissions decrease as the IT is delayed. Based on 18°CA BTDC of IT, the results indicated that the later the moment of hydrogen injection, the higher the MPRR, resulting in the greater the knock intensity. The ITE is less affected by the hydrogen injection phase. When the hydrogen injection phase is delayed, NOx emissions increase slightly.

Effects of Aqueous Solubility and Geochemistry on CO2 Storage in Offshore Basins

The increasing global focus on carbon capture and storage (CCS) has highlighted the potential for offshore CO2 sequestration, particularly following recent successes in onshore projects. This research investigates the qualitative analysis of carbon trapping efficiency in offshore basins, employing a GEM simulator to incorporate factors such as aqueous solubility and geochemistry. The findings reveal that anticlines represent ideal geological structures for carbon storage, effectively trapping a significant portion of injected CO2. For effective mineralization, it is crucial to dissolve CO2 into saline aquifers to generate H+, which facilitates the release of Ca2+ and Al3+ from anorthite. This process leads to the dissolution of anorthite and the precipitation of kaolinite, while calcite transitions from a dissolved state to a precipitated state over time. The analysis indicates that structural trapping provides the highest storage contribution during the injection phase, whereas residual gas trapping becomes dominant by the end of the simulation. Notably, it is observed that the storage contribution of structural trapping decreases from 28.39% to 19.05%, and the percentage increase in storage contributions of residual gas, solubility, ionic, and mineral trapping are 4.12%, 3.25%, 1.69%, and 0.28% for CO2 plus water injection, thereby improving the long-term security of CO2 storage in offshore basins. It is most beneficial to optimize the layout and design of the injection well to ensure a uniform distribution of carbon dioxide and to increase the injection rate.

Two‐phase flows simulations in a space‐time framework for injection molding applications: Comparison with experimental results

AbstractHigh‐resolution numerical simulations of the injection molding process are crucial for precise process and part behavior prediction and tool fabrication. However, the complex flow behavior with high shear rates, rapid cooling as well as the nonlinear material properties post many challenges, and efficient high‐resolution numerical analysis is still subject to research. This study presents a simplified numerical description of the polymer flow and cooling during the injection phase, aiming for efficient and yet accurate simulations of the process. The in‐house finite‐element solver XNS is used to simulate the polymer and air flows, as a two‐phase flow, using the level‐set method. The injected polymer is characterized as a shear‐thinning flow using the non‐Newtonian Cross‐Williams‐Landel‐Ferry rheology model. To reduce the computational time, other polymer model effects such as a precise crystallization kinetics model during the injection phase have been neglected as a result of the findings of a previous study. Heading towards more efficient computations, we use a space‐time discretization, which has a higher convergence rate than commonly used time discretizations and can allow future mesh refinement in time, particularly convenient for our application. The results of the simulation are compared to the propagation of the flow front in an injection molding process of a plate part. The flow front is traced in‐situ by three aligned infrared sensors that detect the temperature increase from the mold wall. The time of flow front propagation between two sensors is in good agreement with experimental results. The peak temperature is calculated lower as compared to the experiment; however the temperature gradients are in good agreement validating the numerical model presented here.

Numerical simulation of seasonal underground hydrogen storage: Role of the initial gas amount on the round-trip hydrogen recovery efficiency

Subterranean structures such as aquifers and depleted gas reservoirs (DGRs) offer a scalable, high-pressure, secure, cost-efficient, and ecologically friendly means of hydrogen (H2) storage. Underground H2 storage (UHS) has emerged as a potential solution to alleviate the imbalance between the fluctuating renewable energy generation and the demand for a constant energy supply. Quantifying the recovery efficiency is of paramount importance in the effort toward large-scale UHS. In this numerical simulation study, we employed a high-resolution grid for the discretization of a synthetic (but realistic) heterogeneous anticline intended as a H2 storage facility, and we assessed the H2 recovery efficiency, and the purity of produced gas associated with UHS in natural reservoirs involving different pre-existing gases and their quantities. All of these studies included an initial phase of cushion gas injection, followed by 4 cycles of H2 storage operations composed of injection-idle-withdrawal periods. The simulation results indicated that the H2 round-trip recovery efficiency RH increased (a) with an increasing number of storage cycles, routinely exceeding 90% and providing evidence of a self-enhancement or self-optimization H2 recovery mechanism and (b) with an increasing amount of pre-existing gas in the storage zone prior to the H2 injections — at the end of the 4-cycle test, the highest RH is associated with a DGR with a pre-existing gas consisting of residual CH4 and additional injected N2, and the lowest RH corresponds to an aquifer with no cushion gas. Conversely, the H2 mass fraction of the produced gas FHQ (a) increased with an increasing number of storage cycles, but (b) decreased rapidly with an increasing amount of pre-existing gas. The presence of a pre-existing gas inevitably leads to severe contamination of the produced H2, which never exceeds 40% in the produced gas, can be as low as 4% in early cycles, and cannot be used as a H2 fuel without gas separation. Aquifer storage without a cushion gas may exhibit the lowest H2 recovery (about 75% in the long run), but yields practically pure H2 that does not require further processing before use. A positive conclusion is that, under the conditions of this study, total H2 losses (including H2 escaping into the caprock, and inaccessible H2 dissolved in the aqueous phase of the formation or remaining in the gas storage zone) are limited and manageable, indicating the technical feasibility of geologic H2 storage.

Mechanical integrity analysis of caprock during the CO2 injection phase

Abstract CO2 geological storage is one of the important means to mitigate the greenhouse effect. The safe underground storage of CO2 largely depends on the mechanical integrity of the caprock. This paper establishes a fluid-solid coupling model for CO2 geological storage to study the changes in pore pressure, vertical displacement, and effective stress in the caprock during the CO2 injection process. Combined with the Mohr-Coulomb criterion, the study determines whether mechanical failure occurs in the caprock. The results indicate that, at the beginning of CO2 injection, significant changes occur in the pore pressure, vertical displacement, and effective stress at the bottom of the caprock near the injection well, which then tend to stabilize; the maximum pore pressure at the bottom of the caprock reaches 36.08 MPa; the caprock near the injection well is considered the most critical area, where the risk of mechanical failure is highest; at the end of CO2 injection, the stress state does not reach the limit, and the caprock remains stable.

Rapid and simultaneous determination of ultrashort-, short- and long- chain perfluoroalkyl substances by a novel liquid chromatography mass spectrometry method

Per- and Polyfluoroalkyl Substances (PFAS) are a group of persistent organic pollutants that have received considerable attention from public and regulatory groups. Due to regulations of long-chain PFAS, the use of short-chain and ultrashort-chain PFAS is rapidly growing. Thus, there is an urgent need to develop quantitative methods for determining PFAS with different chain lengths in various environmental matrices. This study introduces an innovative liquid chromatography-mass spectrometry (LC-MS) system combining large volume injection (LVI) and online solid phase extraction (SPE). This system incorporates three columns: a reverse-phase (RP) column, a weak anion exchange (WAX) trap column, and a hybrid HILIC/ion-exchange (HILIC/IE) column, controlled by two valves. With valve switching, ultrashort-chain PFAS that are not retained by the RP column are enriched by the trap column, while other PFAS are separated by the RP column. The trapped ultrashort PFAS are then transferred to the HILIC/IE column for further separation. The LVI significantly enhances the method's sensitivity, allowing for rapid and simultaneous determination of ultrashort-, short- and long- chain PFAS in aqueous samples. The matrix effects from various environmental samples were evaluated, and the results indicate that this unique LC-MS method is suitable for analyzing all chain-length PFAS in various matrices, including surface water, sewage effluent, and seawater. Finally, this novel LC-MS method was applied to quantify PFAS in various water samples.

Numerical Study on Optimization of Combustion Cycle Parameters and Exhaust Gas Emissions in Marine Dual-Fuel Engines by Adjusting Ammonia Injection Phases

Decarbonizing maritime transport hinges on transitioning oil-fueled ships (98.4% of the fleet) to renewable and low-carbon fuel types. This shift is crucial for meeting the greenhouse gas (GHG) reduction targets set by the IMO and the EU, with the aim of achieving climate neutrality by 2050. Ammonia, which does not contain carbon atoms that generate CO2, is considered one of the effective solutions for decarbonization in the medium and long term. However, the concurrent increase in nitrogen oxide (NOx) emissions during the ammonia combustion cycle, subject to strict regulation by the MARPOL 73/78 convention, necessitates implementing solutions to reduce them through optimizing the combustion cycle. This publication presents a numerical study on the optimization of diesel and ammonia injection phases in a ship’s medium-speed engine, Wartsila 6L46. The study investigates the exhaust gas emissions and combustion cycle parameters through a high-pressure injection strategy. At an identified 7° CAD injection phase distance between diesel and ammonia, along with an optimal dual-fuel start of injection 10° CAD before TDC, a reduction of 47% in greenhouse gas emissions (GHG = CO2 + CH4 + N2O) was achieved compared to the diesel combustion cycle. This result aligns with the GHG reduction target set by both the IMO and the EU for 2030. Additionally, during the investigation of the thermodynamic combustion characteristics of the cycle, a comparative reduction in NOx of 4.6% was realized. This reduction is linked to the DeNOx process, where the decrease in NOx is offset by an increase in N2O. However, the optimized ammonia combustion cycle results in significant emissions of unburnt NH3, reaching 1.5 g/kWh. In summary, optimizing the combustion cycle of dual ammonia and diesel fuel is essential for achieving efficient and reliable engine performance. Balancing combustion efficiency with emission levels of greenhouse gases, unburned NH3, and NOx is crucial. For the Wartsila 6L46 marine diesel engine, the recommended injection phasing is A710/D717, with a 7° CAD between injection phases.

Multiphysics framework for cost-effective, long-term monitoring of carbon storage in a carbonate reservoir

We evaluate an effective and cost-efficient multiphysics approach for long-term monitoring of carbon storage in carbonate reservoirs. A key focus of our study is to advocate for a cost-effective, long-term monitoring strategy for carbon storage projects through the integration of surface and borehole multiphysics measurements. By leveraging technologies related to electromagnetic (EM) and gravity methods, we present a framework that addresses the monitoring of the dynamic behavior of injected CO2 over an extended period. The modeling setup integrates realistic static reservoir models with simulated dynamic saturation models to provide results as close as possible to real experimental conditions. Results demonstrate the high sensitivity of EM fields to changes in reservoir CO2 saturation, especially when surface-to-reservoir acquisition configurations are adopted. Additionally, gravity simulations, employing three-axis vector surface gravity measurements and borehole vector gravity, effectively capture density variations over time. Our proposed framework highlights the sequential use of seismic imaging for preinjection site characterization and the transition to EM and gravity surveys for continuous monitoring during and after the injection phases. The multiphysics simulation results performed on realistic carbon storage conditions contribute to the evolving landscape of effective geophysical CO2 monitoring technology for reliable long-term reservoir management.

RPV top and bottom break SBLOCA with passive emergency core cooling system using ATLAS test facility

A SBLOCA test, named as C2.1 in the frame of the OECD/NEA ATLAS3 project, using a passive emergency core cooling system (PECCS) was performed by Korea Atomic Energy Research Institute (KAERI). In the test, two simultaneous 2-inch equivalent breaks occurred at top and bottom nozzles of the reactor pressure vessel of ATLAS test facility. The main purpose of the test is to investigate thermal hydraulic transient behavior in a reactor coolant system (RCS) during a SBLOCA scenario and to evaluate the effectiveness of PECCS. From the observation on thermal hydraulic phenomena during the test, the test period was divided into three characteristic phases such as pressure plateau, safety injection, and clad temperature re-increase phases. Continuous inventory loss of the primary loop through two break nozzles led to a primary system pressure decrease and a clad temperature increase. Even though high-pressure safety injection tanks (HPSITs) were actuated in an early stage of the pressure plateau phase, safety injection from HPSITs, however, were not actually injected. Safety injection flows from the HPSITs and SITs were practically injected to the downcomer only after the opening of automatic depressurization valves (ADVs). With a continuous decrease of a primary system pressure, low-pressure (LP) injection was started. However, LP injection could not change the increasing trend of the clad temperatures. Post-test calculations were performed using MARS-KS 1.4, and calculation results were compared with those of the test.

GRB 210610B: The Internal and External Plateau as Evidence for the Delayed Outflow of Magnetar

After launching a jet, outflows of magnetar were used to account for the achromatic plateau of afterglow and the early X-ray flux plateau known as “internal plateau”. The lack of detecting magnetic dipole emission together with the energy injection feature in a single observation poses confusion until the long gamma-ray burst (GRB) 210610B is detected. GRB 210610B is presented with an optical bump following an early X-ray plateau during the afterglow phase. The plateau followed by a steep decline flux overlays in the steadily decaying X-ray flux with index α X,1 ∼ 2.06, indicating an internal origin and that can be fitted by the spin-down luminosity law with the initial plateau luminosity log10LX∼48.29ergs−1 and the characteristic spin-down timescale T ∼ 2818 s. A subsequent bump begins at ∼4000 s in the R band with a rising index α R,1 ∼ − 0.30 and peaks at ∼14125 s, after which a decay index α R,2 ∼ 0.87 and finally transiting to a steep decay with α R,3 ∼ 1.77 achieve the closure relation of the external shock for the normal decay phase as well as the magnetar spin-down energy injection phase, provided that the average value of the photon index Γ γ = 1.80 derived from the spectral energy distributions (SEDs) between the X-ray and optical afterglow. The closure relation also works for the late X-ray flux. Akin to the traditional picture of GRB, the outflow powers the early X-ray plateau by dissipating energy internally and collides with the leading decelerating blast burst as time goes on, which could interpret the exotic feature of GRB 210610B. We carry out a Markov Chain Monte Carlo simulation and obtain a set of best parameters: ϵ B ≃ 4.7 × 10−5, ϵ e ≃ 0.15, E K,iso ≃ 4.6 × 1053erg, Γ0 ≃ 832, A * ≃ 0.10, L inj,0 ≃ 3.55 × 1050erg s−1. The artificial light curve can fit the afterglow data well. After that, we estimated the average Lorentz factor and the X-ray radiation efficiency of the later ejecta are 35% and 0.13%, respectively.

Accelerating CO2 Storage Site Characterization through a New Understanding of Favorable Formation Properties and the Impact of Core-Scale Heterogeneities

CO2 sequestration in deep geologic formations can permanently reduce atmospheric CO2 emissions and help to abate climate change. Target formations must undergo a time- and resource-intensive site evaluation process, assessing storage capacity, environmental safety, and suitability for CO2 trapping via reactive transport models based on data from a limited number of core samples. As such, simulations are often simplified and omit heterogeneities in formation properties that may be significant but are not well understood. To facilitate more rapid site assessment, this work first defines the aquifer properties of favorable storage formations through the analysis of promising and active storage sites. Data show quartz is the most prevalent formation mineral with carbonate minerals, highly reactive with injected CO2, present in over 75% of formations. Porosity and permeability data are highly clustered at 10–30% and 10–1000 mD. Field-scale reactive transport simulations are then constructed and used to analyze CO2 trapping efficiency. The models consider porosity and carbonate mineral heterogeneity as well as the impacts of typical temperature gradients. Simulated sequestration efficiencies are compared to results from a comparable homogenous model to understand the implications of aquifer non-uniformities. The results show a lower sequestration efficiency in the homogeneous model during the injection phase. During the post-injection phase, the homogenization of porosity and carbonate mineralogy results in a higher sequestration efficiency. Incorporating the temperature gradient also increases the sequestration efficiency. Importantly, the maximum deviation between the homogeneous and heterogeneous simulations at the end of the 50-year study period is only ~10%. Larger impacts may be incurred for properties outside the defined, promising ranges suggested here.

Plasmoid drift and first wall heat deposition during ITER H-mode dual-SPIs in JOREK simulations

The heat flux mitigation during the thermal quench (TQ) by the shattered pellet injection (SPI) is one of the major elements of disruption mitigation strategy for ITER. It’s efficiency greatly depends on the SPI and the target plasma parameters, and is ultimately characterised by the heat deposition on to the plasma facing components. To investigate such heat deposition, JOREK simulations of neon-mixed dual-SPIs into ITER baseline H-mode and a ‘degraded H-mode’ with and without good injector synchronization are performed with focus on the first wall heat flux and its energy impact. It is found that low neon fraction SPIs into the baseline H-mode plasmas exhibit strong major radial plasmoid drift as the fragments arrive at the pedestal, accompanied by edge stochasticity. Significant density expulsion and outgoing heat flux occurs as a result, reducing the mitigation efficiency. Such drift motion could be mitigated by injecting higher neon fraction pellets, or by considering the pre-disruption confinement degradation, thus improving the radiation fraction. The radiation heat flux is found to peak in the vicinity of the fragment injection location in the early injection phase, while it relaxes later on due to parallel impurity transport. The overall radiation asymmetry could be significantly mitigated by good synchronization. Time integration of the local heat flux is carried out to provide its energy impact for wall heat damage assessment. For the baseline H-mode case with full pellet injection, melting of the stainless steel armour of the diagnostic port could occur near the injection port, which is acceptable, without any melting of the first wall tungsten tiles. For the degraded H-mode cases with quarter-pellet SPIs, which have 1/4 total volume of a full pellet, the maximum energy impact approaches the tolerable limit of the stainless steel with un-synchronized SPIs, and stays well below such limit for the perfectly synchronized ones.

Enhancing Combustion Stability in Biodiesel Engines: The Plausibility of n-Butanol Injection Phasing and Reactivity-Controlled Compression Ignition–An Experimental Endeavour

This study explores the synergistic effect of injection phasing on reactivity-controlled compression ignition strategies upon the combustion and stability indices of biodiesel-fuelled single-cylinder four-stroke diesel engines. Mahua Biodiesel was used as the primary fuel, and n-butanol was injected into the manifold to achieve that strategy. The tests were conducted with varying the start of pilot-main injection timing, energy share of biodiesel in split injection and energy share of butanol. This work also entails the various combustion characteristics and the corresponding consequences on the engine’s performance-emission. Ignition delay is shortened with retarded injection timing. At the same time, combustion duration is reduced with higher butanol share and advanced injection timing of biodiesel. The butanol injection and advanced pilot biodiesel injection timing revealed the advancement of combustion phasing. In conjunction with n-butanol port fuel injection, the current study demonstrates the noteworthy and potential superiority of n-butanol as the less reactive constituent. Shortened ignition delay exhibited improved performance and UHC-CO footprint. This study highlights the maximum reduction in regulated emissions compared to operations solely relying on 100% biodiesel. The occurrence of CA50 at 5°–7° CA revealed a maximum decrease in NOX-UHC-CO-CO2 emissions compared to the B100 fuelled strategy. The reduction percentages observed were 53.4%, 97%, 81.1%, and 53.2%, respectively.

Mechanisms for Microseismicity Occurrence Due to CO2 Injection at Decatur, Illinois: A Coupled Multiphase Flow and Geomechanics Perspective

ABSTRACT We numerically investigate the mechanisms that resulted in induced seismicity occurrence associated with CO2 injection at the Illinois Basin–Decatur Project (IBDP). We build a geologically consistent model that honors key stratigraphic horizons and 3D fault surfaces interpreted using surface seismic data and microseismicity locations. We populate our model with reservoir and geomechanical properties estimated using well-log and core data. We then performed coupled multiphase flow and geomechanics modeling to investigate the impact of CO2 injection on fault stability using the Coulomb failure criteria. We calibrate our flow model using measured reservoir pressure during the CO2 injection phase. Our model results show that pore-pressure diffusion along faults connecting the injection interval to the basement is essential to explain the destabilization of the regions where microseismicity occurred, and that poroelastic stresses alone would result in stabilization of those regions. Slip tendency analysis indicates that, due to their orientations with respect to the maximum horizontal stress direction, the faults where the microseismicity occurred were very close to failure prior to injection. These model results highlight the importance of accurate subsurface fault characterization for CO2 sequestration operations.

Fully automated explainable abdominal CT contrast media phase classification using organ segmentation and machine learning.

Contrast-enhanced computed tomography (CECT) provides much more information compared to non-enhanced CT images, especially for the differentiation of malignancies, such as liver carcinomas. Contrast media injection phase information is usually missing on public datasets and not standardized in the clinic even in the same region and language. This is a barrier to effective use of available CECT images in clinical research. The aim of this study is to detect contrast media injection phase from CT images by means of organ segmentation and machine learning algorithms. A total number of 2509 CT images split into four subsets of non-contrast (class #0), arterial (class #1), venous (class #2), and delayed (class #3) after contrast media injection were collected from two CT scanners. Seven organs including the liver, spleen, heart, kidneys, lungs, urinary bladder, and aorta along with body contour masks were generated by pre-trained deep learning algorithms. Subsequently, five first-order statistical features including average, standard deviation, 10, 50, and 90 percentiles extracted from the above-mentioned masks were fed to machine learning models after feature selection and reduction to classify the CT images in one of four above mentioned classes. A 10-fold data split strategy was followed. The performance of our methodology was evaluated in terms of classification accuracy metrics. The best performance was achieved by Boruta feature selection and RF model with average area under the curve of more than 0.999 and accuracy of 0.9936 averaged over four classes and 10 folds. Boruta feature selection selected all predictor features. The lowest classification was observed for class #2 (0.9888), which is already an excellent result. In the 10-fold strategy, only 33 cases from 2509 cases (∼1.4%) were misclassified. The performance over all folds was consistent. We developed a fast, accurate, reliable, and explainable methodology to classify contrast media phases which may be useful in data curation and annotation in big online datasets or local datasets with non-standard or no series description. Our model containing two steps of deep learning and machine learning may help to exploit available datasets more effectively.

Separation of hydrogen from 10 % hydrogen + methane mixtures using double-stage Vacuum Swing Adsorption (VSA)

Transportation of hydrogen by blending it into the existing natural gas infrastructure is one economical way of having a green future. After co-transportation of hydrogen this way, hydrogen deblending from natural gas is needed at various locations for different end-users. The hydrogen content in pipelines at the primary injection phase will be low (<20 %) which makes the separation challenging. The goal of the current study is to investigate the extraction of high purity hydrogen from a 10 % hydrogen + natural gas mixture using Vacuum Swing Adsorption (VSA). A four-bed VSA plant using activated carbon was used to conduct the experiments in our lab using a binary mixture of 10 % H2 + CH4 (% mol/mol). High purity hydrogen (99 %) was achieved at 102 kPa feed pressure. After validation of our simulation tool with experimental results, Aspen Adsorption software was used to assess the performance of producing 99 % hydrogen purity using a double-stage VSA process at small scale. Results revealed that achieving high-purity hydrogen using a double-stage VSA, by upgrading H2 from 10 % to 50 % in the first stage and then to 99 % H2 in the second stage leads to better separation performance and less energy consumption than a single stage VSA for the same separation target. Afterwards, a five-bed double VSA system at industrial scale was simulated using Aspen Adsorption, to produce high hydrogen purity from a representative 10 % hydrogen + natural gas mixture. High purity hydrogen (>99 %) along with high recovery (>82 %) were achieved at a feed pressure of 110 kPa.

Shear Wave Velocity Applications in Geomechanics with Focus on Risk Assessment in Carbon Capture and Storage Projects

Shear wave velocity (Vs) has significant applications in geoengineering investigations. With the ongoing rise in carbon capture and storage (CCS) initiatives, the role of Vs in monitoring the CO2 sequestration sites is escalating. Although many studies have been conducted to assess CCS-induced risks, no inclusive research has been conducted integrating those investigations. This study strives to collate and integrate the applications of Vs in geoscience with an emphasis on CCS risk assessment. Based on this research, major CCS-induced risks were detected: induced seismicity, caprock failure, groundwater contamination, fault reactivation, and reservoir deformation. These risks were inclusively described, and the mathematical formulations incorporating the Vs parameter in risk analysis were elaborated. It was concluded that Vs applications can be further extended in monitoring CO2 plume migration, optimizing CO2 injection pressures, preventing shallow water contamination, and predicting CCS-induced seismic events. All these applications require fully coupled hydromechanical analysis based on poroelasticity theory. Hence, various factors including pore pressure, in situ stresses, faults distribution, and poroelastic parameters must be carefully determined before the CO2 injection phase. The mathematical formulations presented in the present study are quite applicable for granting the safety and long-term success of subsurface carbon sequestration.