Pressure Regime Research Articles

Impact of parasitic heat fluxes on deep sub-ambient radiative coolers under variable pressure

Passive daytime radiative cooling has proven to be a promising technology which allows objects to cool down by shedding heat to space, acting as a large thermal sink. However, the end equilibrium temperature of a radiative sky cooler (RSC) is limited by the parasitic heat fluxes. Operating RSC in vacuum suppresses the convective heat fluxes, but realizing commercial deep sub-ambient RSC system is rather challenging due to system complexity and sub-component material constraints. In this work, the behavior of the RSC under varying pressure and sub-component system parameters like thermal conductivity of medium and holder and back reflectors is studied. An analytical model is developed taking these parameters as input to analyze and predict RSC performance. A spectrally selective RSC with silver back reflector and polysilazane polymer as emitter having emissivity of 0.85 in the atmospheric window is fabricated to study its deep sub-ambient cooling performance. Through sequential measurements done under controlled environment using liquid nitrogen as cryogenic heat sink, the influence of individual parasitic heat fluxes on the RSC under variable pressure is comprehensively investigated. A sub-ambient cooling of 10 °C under ambient pressure, and 33 °C at a decreased pressure of 1.63 × 10-3 Pa was achieved. The experimental results are in good agreement with our modeled prediction. Subjected on intended usage and desired cooling performance from the RSC system, a rational design of sub-components and operational pressure regimes can be suggested from this study. We believe that these findings have multiple practical implications for designing future deep sub-ambient RSC systems and explores scopes for optimization.

The reactive flow evolution of the polymer-bonded explosive PBX 9502: Experiments and model validation in extreme pressure regimes

The shock-to-detonation transition properties of the triaminotrinitrobenzene based PBX 9502 high explosive (HE) are experimentally and computationally explored in extremely high input pressure conditions. These include both slightly sub-Chapman–Jouguet and overdriven input pressure conditions, namely, ∼25 and ∼31 GPa, respectively. Our experiments capture the transient buildup of a shock-induced reaction via measurement of HE and polymethyl methacrylate window interface particle velocity profiles for a variety of sample thicknesses for this insensitive HE. These observations necessitate extremely thin explosive samples, and the high rates of reaction provide a considerable challenge to optical diagnostics. Samples at these thicknesses also provide an opportunity for evaluation of potential micro-structure effects on the resulting shock-to-detonation-transition measurements. To address this, the thin samples are also characterized via x-ray micro-computed tomography. Finally, a pair of previously established continuum-level detonation performance modeling approaches for PBX 9502 were used to analyze the experiments. The employed model variants crucially differ in their definition of each model’s empirical reaction rate functional form, utilization of shock state quantities, and local flow variable dependencies. As a result, the present experiments provide a novel platform to evaluate the quantitative and qualitative consequences stemming from these modeling choices in a challenging initiation scenario, largely beyond the chosen calibration range of either model. This new experimental information will provide a platform for both improved physics and model parameterizations for this well-studied explosive.

Wearable Capacitive Tactile Sensor Based on Porous Dielectric Composite of Polyurethane and Silver Nanowire.

In recent years, the implementation of wearable and biocompatible tactile sensing elements with sufficient response into healthcare, medical detection, and electronic skin/amputee prosthetics has been an intriguing but challenging quest. Here, we propose a flexible all-polyurethane capacitive tactile sensor that utilizes a salt crystal-templated porous elastomeric framework filling with silver nanowire as the composite dielectric material, sandwiched by a set of polyurethane films covering silver nanowire networks as electrodes. With the aids of these cubic air pores and conducting nanowires, the fabricated capacitive tactile sensor provides pronounced enhancement of both sensor compressibility and effective relative dielectric permittivity across a broad pressure regime (from a few Pa to tens of thousands of Pa). The fabricated silver nanowire-porous polyurethane sensor presents a sensitivity improvement of up to 4-60 times as compared to a flat polyurethane device. An ultrasmall external stimulus as light as 3 mg, equivalent to an applied pressure of ∼0.3 Pa, can also be clearly recognized. Our all-polyurethane capacitive tactile sensor based on a porous dielectric framework hybrid with conducting nanowire reveals versatile potential applications in physiological activity detection, arterial pulse monitoring, and spatial pressure distribution, paving the way for wearable electronics and artificial skin.

Basin-Scale Hydraulic Evaluation of Groundwater Flow Controlled Biogenic Gas Migration and Accumulation in the Central Pannonian Basin

Biogenic or microbial methane has an increasing share in the global gas resource base, though its exploration still faces challenges and welcomes innovations. Critical elements of its migration and accumulation models are the groundwater flows which gather and transport the gas in aqueous solution, and the seal rocks or aquifers which lead groundwater flows horizontally over great distances. This paper intends to introduce the hydraulic trap concept into these models, which is able to drive fluids horizontally without an overlying seal rock. Since hydraulic traps can evolve as a result of the interplay of regional groundwater flow systems, the basin-scale hydraulic evaluation methodology which was developed for the analysis of these systems was further improved by this study to focus on their interplay. The improved methodology was applied on measured hydraulic data in a study area in the Central Pannonian Basin (Hungary) around the Hajdúszoboszló gas field where as a result, the first groundwater flow controlled dissolved biogenic gas migration and accumulation model could be set up. In addition, the proposed methodology can be used in any terrestrial sedimentary basin, and in particular, where topography-driven flow systems are underlaid by an abnormal pressure regime.

On lift enhancement and noise reduction in serrated gurney flap airfoil of wind turbines using proper orthogonal decomposition

Based on the steady simulation results obtained by the SST k-ω turbulence model, large eddy simulation (LES) and proper orthogonal decomposition (POD) are used to examine the static pressure and vorticity modes of the wind turbine airfoil with serrated Gurney flaps (SGFs) and the baseline at α = 12° and 20°. The effect of SGF on the aerodynamic performance and radiated noise is investigated, and the influence of serration's span structure on the vorticity mode distribution is discussed. By analyzing the main modes and mode coefficients of the flow field, the mechanism of lift enhancement and noise reduction of SGF is explained. The results indicate that an airfoil with a SGF(ASGF) of 6.7%c width and 0.8%c height can effectively improve the lift coefficient within the investigated attack angles, delay stall by about 3°, and reduce the radiated noise of the airfoil by 0.51 and 4.40 dB, respectively, at 12° and 20°. Static pressure distribution analysis reveals that the SGF can significantly widen the positive pressure zone of the pressure surface, improve the ultra-low pressure regime of the suction surface, and make the pressure distribution on the suction surface more uniform, which increase the lift-drag ratio of ASGF. The POD method effectively extracts the most relevant mode of the airfoil surface radiated noise. The unsteady feature of the main flow of the airfoil is the vortices on the suction surface. The ASGF can effectively restrain the vortex separation on the suction surface and reduce the vorticity, delaying the stall and reducing the radiated noise of the airfoil surface.

Expertise-based systematic guidelines for chiller retrofitting in healthcare facilities

Air Conditioning and Mechanical Ventilation (ACMV) generally consume more than half of the energy consumption in commercial buildings in a tropical region. In healthcare facilities, the ACMV systems must comply with the following crucial parameters: indoor air quality, which greatly impacts the thermal comfort of occupants, as well as pressure regime regulations and standards, particularly in critical areas. Due to the high cost of operating the ACMV system, many health facilities in Malaysia have embarked on energy efficiency initiatives. Many have replaced their chillers with magnetic-bearing chiller compressors to benefit from cost reduction. However, despite the replacement, it was found that not all healthcare facilities benefited fully from improved air condition systems other than the higher chillers' coefficient of performance obtained from the new installation. The paper's main contribution is to offer a comprehensive and systematic guideline for facility managers to evaluate healthcare facilities ACMV systems and provides solutions that match the healthcare facilities ventilation requirements standards in making effective decision before embarking chiller retrofitting. The proposed guideline is based on the experience and observation of the expertise through energy auditing of the ACMV system and chiller retrofitting evaluation at the healthcare facilities in Malaysia. It may contribute towards more cost-effective management of ACMV system at healthcare facilities in Malaysia while assisting facility managers on chiller retrofitting decision making. More importantly, the guideline has the potential to support sustainable performance of the ACMV system.

High-pressure response of vibrational properties of b-As x P1–x : in situ Raman studies

The structural evolution of black arsenic-phosphorous (b-As x P1–x ) alloys with varying arsenic concentrations was investigated under hydrostatic pressure using in situ Raman spectroscopy. High-pressure experiments were conducted using a diamond anvil cell, which revealed pressure-induced shifts in vibrational modes associated with P–P bonds (A 1 g , A 2 g , ), As–As bonds (A 1 g , A 2 g , ), and As–P bonds in b-As x P1–x alloys. Two distinct pressure regimes were observed. In the first regime (region I), all vibrational modes exhibited a monotonic upshift, indicating phonon hardening due to hydrostatic pressure. In the second regime (region II), As0.4P0.6 and As0.6P0.4 alloys displayed a linear blueshift (or negligible change in some modes) at a reduced rate, suggesting local structural reorganization with less compression on the bonds. Notably, the alloy with the highest As concentration, As0.8P0.2, exhibited anomalous behavior in the second pressure regime, with a downward shift observed in all As–As and As–P Raman modes (and some P–P modes). Interestingly, the emergence of new peaks corresponding to the Eg mode and A 1g mode of the gray-As phase was observed in this pressure range, indicating compressive strain-induced structural changes. The anomalous change in region II confirms the formation of a new local structure, characterized by elongation of the P–P, As–As, and As–P bonds along the zigzag direction within the b-As x P1–x phase, possibly near the grain boundary. Additionally, a gray-As phase undergoes compressive structural changes. This study underscores the significance of pressure in inducing structural transformations and exploring novel phases in two-dimensional materials, including b-As x P1–x alloys.

Phylotranscriptomic analyses reveal deep gene tree discordance in Camellia (Theaceae)

Gene tree discordance is a significant legacy of biological evolution. Multiple factors can result in incongruence among genes, such as introgression, incomplete lineage sorting (ILS), gene duplication or loss. Resolving the background of gene tree discordance is a critical way to uncover the process of species diversification. Camellia, the largest genus in Theaceae, has controversial taxonomy and systematics due in part to a complex evolutionary history. We used 60 transcriptomes of 55 species, which represented 15 sections of Camellia to investigate its phylogeny and the possible causes of gene tree discordance. We conducted gene tree discordance analysis based on 1,617 orthologous low-copy nuclear genes, primarily using coalescent species trees and polytomy tests to distinguish hard and soft conflict. A selective pressure analysis was also performed to assess the impact of selection on phylogenetic topology reconstruction. Our results detected different levels of gene tree discordance in the backbone of Camellia, and recovered rapid diversification as one of the possible causes of gene tree discordance. Furthermore, we confirmed that none of the currently proposed sections of Camellia was monophyletic. Comparisons among datasets partitioned under different selective pressure regimes showed that integrating all orthologous genes provided the best phylogenetic resolution of the species tree of Camellia. The findings of this study reveal rapid diversification as a major source of gene tree discordance in Camellia and will facilitate future investigation of reticulate relationships at the species level in this important plant genus.

Top-Down Protein Analysis by Tandem-Trapped Ion Mobility Spectrometry/Mass Spectrometry (Tandem-TIMS/MS) Coupled with Ultraviolet Photodissociation (UVPD) and Parallel Accumulation/Serial Fragmentation (PASEF) MS/MS Analysis.

"Top-down" proteomics analyzes intact proteins and identifies proteoforms by their intact mass as well as the observed fragmentation pattern in tandem mass spectrometry (MS/MS) experiments. Recently, hybrid ion mobility spectrometry-mass spectrometry (IM/MS) methods have gained traction for top-down experiments, either by allowing top-down analysis of individual isomers or alternatively by improving signal/noise and dynamic range for fragment ion assignment. We recently described the construction of a tandem-trapped ion mobility spectrometer/mass spectrometer (tandem-TIMS/MS) coupled with an ultraviolet (UV) laser and demonstrated a proof-of-principle for top-down analysis by UV photodissociation (UVPD) at 2-3 mbar. The present work builds on this with an exploration of a top-down method that couples tandem-TIMS/MS with UVPD and parallel-accumulation serial fragmentation (PASEF) MS/MS analysis. We first survey types and structures of UVPD-specific fragment ions generated in the 2-3 mbar pressure regime of our instrument. Notably, we observe UVPD-induced fragment ions with multiple conformations that differ from those produced in the absence of UV irradiation. Subsequently, we discuss how MS/MS spectra of top-down fragment ions lend themselves ideally for probability-based scoring methods developed in the bottom-up proteomics field and how the ability to record automated PASEF-MS/MS spectra resolves ambiguities in the assignment of top-down fragment ions. Finally, we describe the coupling of tandem-TIMS/MS workflows with UVPD and PASEF-MS/MS analysis for native top-down protein analysis.

Defect-induced confinement in zirconium metal-organic frameworks for enhanced hydrogen adsorption

Hydrogen is an essential gas to multiple industrial processes, and due to its high gravimetric density, it promises a large potential as a clean energy source. The risks of hydrogen at low pressures, however, have deterred substantial progress in improving hydrogen storage technology. Metal-organic frameworks (MOFs) are crystalline porous materials that have emerged as excellent gas adsorbents, and their gas storage properties can be tuned using a variety of synthetic methods. Herein, we leveraged the tunability and porosity of MOFs to introduce defect engineering as a method to improve hydrogen storage technology at low pressure regimes in two zirconium-based MOFs (Zr-MOFs), UiO-66 and NU-403, which feature ideal pore apertures (7 Å) for studying the confinement effect and ease of defect engineering. By reducing the number of defects in these Zr-MOFs, and thereby decreasing the quantity of larger pores, we can induce a structural confinement effect that increases the selectivity of hydrogen adsorption. A combination of thermogravimetric analysis (TGA) and nuclear magnetic resonance (NMR) spectroscopic analysis enabled quantification of the defect levels, confirming that each sample exhibits a distinct level of defectiveness. Gas adsorption measurements revealed that the adsorption of hydrogen is greatly enhanced in samples with fewer defects, while the calculated isosteric heats of enthalpy (Qst) indicate that there are no open metal sites in these MOFs that could be the cause. Overall, we can conclude that defect engineering for pore tailoring is a viable strategy to enhance hydrogen adsorption at low-pressure regimes.

Deciphering the origin(s) of H and Cl in Apollo 15 quartz monzodiorites: Evidence for multiple processes and reservoirs

Apollo 15 quartz monzodiorites (QMDs) are reported to contain some of the most deuterium-depleted apatite found in lunar samples. In this study, apatite from six Apollo 15 QMDs, including three samples from 15405 not previously investigated, were analyzed for their H and Cl isotopes. Apatite in 15405 are extremely 2H (or D)-poor, with δD values ranging from −658 ± 53 to −378 ± 113‰, comparable to apatite data from related samples 15403 and 15404. In addition to new H isotope data, the first Cl-isotope data for lunar QMDs are presented. Apatite in 15405 and related samples are enriched in 37Cl with respect to Earth, with measured δ37Cl values ranging from +13 to +37‰. These values are within the reported δ37Cl range for KREEP-rich samples. The fact that the Cl isotopic composition of apatite in QMDs are similar to those in other lunar lithologies, but the H isotopic data are distinct and unique, provides possible further evidence for the existence of a D-poor reservoir in the lunar interior. Raman spectroscopy of the silica polymorph in sample 15405 reveals it to be a mixture of quartz and cristobalite. Based on available experimental data on the stability of various silica phases over a range of pressure and temperature regime, a deep-seated origin in the crust for QMDs may be possible which would support an endogenous origin of the H-Cl isotope systematics of the QMDs. The role of impact-induced transformation of silica phases and its contributing towards low D/H ratio in apatite, however, cannot be ruled out.

Weathering the hunt: The role of barometric pressure in predator insects' foraging behaviour.

Abiotic factors strongly influence ecological interactions and the spatial distribution of organisms. Despite the essential role of barometric pressure, its influence on insect behaviour remains poorly understood, particularly in predators. The effect of barometric pressure variation can significantly impact biological control programs involving entomophagous insects, as they must efficiently allocate time and energy to search for prey in challenging environments. We investigated how predatory insects from different taxonomic groups (Coleoptera, Dermaptera and Neuroptera) adapt their foraging behaviour in response to variations in barometric pressure (low, medium and high). We also examined the response of different life stages to changes in pressure regimes during foraging activities. Our results showed that the searching time of Doru luteipes (Dermaptera: Forficulidae) was faster in a favourable high-pressure regime, whereas Chrysoperla externa (Neuroptera: Chrysopidae) and Eriopis connexa (Coleoptera: Coccinellidae) had similar searching times under varying pressure regimes. Although no differences in prey feeding time were observed among the studied species, the consumption rate was influenced by low barometric pressure leading to a decrease in the number of preyed eggs. Moreover, we provide novel insights into how hemimetabolous (D. luteipes) and holometabolous (E. connexa) species at different life stages respond to barometric pressure. Doru luteipes nymphs and adults had similar consumption rates across all pressure regimes tested, whereas E. connexa larvae consumed fewer eggs under low barometric pressure, but adults were unaffected. This highlights the importance of investigating how abiotic factors affect insects foraging efficiency and predator-prey interactions. Such studies are especially relevant in the current context of climate change, as even subtle changes in abiotic factors can have strong effects on insect behaviour. Barometric pressure is a key meteorological variable that serve as a warning signal for insects to seek shelter and avoid exposure to weather events that could potentially increase their mortality. Understanding the effects of barometric pressure on predatory insects' behaviour can help us develop more effective pest management strategies and promote the resilience of agroecosystems. We provide new insights into the complex relationship between barometric pressure and predator-prey interactions.

An investigation of fatigue response of well cement under cyclic loading and impact on zonal isolation performance

Cyclic bottomhole pressure fluctuation is very prevalent in modern well construction and enhanced petroleum recovery applications and poses a great challenge to annular seal integrity and successful zonal isolation, even in cases where the cement seal exhibits excellent initial quality. Thus, annular sealants must be designed to mitigate or minimize the deleterious effects of cyclic pressure fluctuations on the annular seal. Optimal cement designs for this purpose require a proper understanding of damage modes and mechanisms associated with a cyclic pressure regime, as well as the impact of the cement mechanical integrity evolution on the leakage of the cemented annulus. Using four cement formulations with distinct mechanical and microstructural properties, we investigated the mechanical integrity evolution and leakage characteristics of cemented pipe specimens subjected to confinement pressure fluctuations. Via microscopic inspection of the cement/pipe interface after pressure cycling and permeability measurements during pressure cycling, we attempted to correlate cement properties with leakage and suggest a recommendation for optimal cement design and successful zonal isolation in wellbores subjected to cyclic pressure. Test data indicate that under high enough pressure variation, interfacial cracking at the cement pipe interface is unavoidable and the cement seal's ability to maintain zonal isolation will be dependent on the microstructural morphology and microscale mechanical resilience of the cement formulation. Stiffer conventional cements also appear to have a higher chance of leakage through non-interfacial fractures than their more flexible counterparts. Latex cements show great promise for effective zonal isolation under cyclic bottomhole pressure conditions and should be studied in more detail.

Ultrahigh vacuum pressure measurement using magneto-optical trap on atom chip

In this work, the UHV background pressure as low as 1.1×10−10 Torr has been measured using the loss rate characteristics of a vapor-loaded magneto-optical trap (MOT) formed on an atom chip in a UHV chamber. The loss rate due to non-rubidium (Rb) gases in the background in the chamber has been estimated by operating the MOT in low cooling beam intensities and low Rb pressure regimes simultaneously. Using this approach, we minimized the contributions of the intra-trap collisions as well as background MOT species collisions to the measured trap loss rate in our setup. These results can be useful for development of cold-atom based UHV pressure standards.

Ground state dynamically stable phases for fluorine in the TPa pressure regime by evolutionary algorithms

In this work, we tested ab initio methods combined with evolutionary algorithms for searching stable crystalline structures for solid fluorine in the Tera-Pascal (TPa) regime. We performed several structural searches using the USPEX code, at pressures that spanned the range from 1 to 5 TPa, considering up to 16 atoms per unit-cell for selected pressures. Our findings partially support recent studies by validating the transformation of fluorine from a molecular form, Cmca, into an intermediate polymeric form before its eventual dissociation. Enthalpy comparisons between candidate structures of fluorine at high pressure show a direct transition from the molecular phase Cmca into a Pm¯3n extended structure at 2.7 TPa, the later consisting of linear chains and independent atoms, which disagrees with previous conflicting reports that proposed two other intermediate phases to also exist as stable crystalline forms close to 3 TPa at zero temperature.

An anisotropic stellar fluid configuration with vanishing complexity

In this work, we construct a new stellar model in the regime of anisotropic fluid pressure using the concept of vanishing complexity for spherically symmetric fluid distributions (Herrera in Phys Rev D 97:044010, 2018) and a convenient ansatz in order to close the Einstein’s field equations. The resulting model fulfills the fundamental physical acceptability stellar conditions for a specific set of compactness factor. The stability and its response against fluctuations in the matter sector is also investigated.

Artificial neural network modelling for predicting classical air pressure profile curves in building drainage systems

Water trap seal loss can lead to the ingress of foul odours from the sewer network carrying harmful pathogens which can affect the health of building occupants. This loss is due to excessive negative or positive pressures within the system as a consequence of rapidly changing flow due to the unsteady nature of air and water flow discharges from appliances. This pressure regime within the system is often represented by a pressure profile along the height of the main vertical stack in the Building Drainage System (BDS). Experimental data from peer-reviewed literature and data from a unique 34-storey drainage test rig have been used as pressure profile data (Test data) for an Artificial Neural Network (ANN) model. Discharge input height (storey number) and discharge flow rate are considered to be the two independent input parameters and the pressure along the vertical stack is considered to be the output. In this work, both a Feed Forward and Back Propagation (FFBP) ANN model and a Radial Basis Function (RBF) ANN model have been used to train the algorithm. The work has confirmed the applicability of the FFBP-ANN model for steady two-phase fluid flow phenomena in BDS and allows for the prediction of pressures in a system for which no pressure data exists, by the prediction of modelled weights, based only on its physical and flow characteristics. Practical Application: Of great concern to designers of building drainage systems (BDS) is the control of pressure fluctuations within the system to prevent water trap seal loss. Prediction of a pressure profile based on the characteristics of the building – e.g. height, location of water discharge, discharge flow rate and ventilation type, would therefore increase confidence in designs, particularly in tall buildings. The work presented here addresses, for the first time, the applications of two ANN models for predicting the pressure profile in the BDS vertical stack of multi-storey buildings.

Positive and Negative Pressure Regimes in Anisotropically Strained V2O3 Films

AbstractThe metal‐insulator phase transitions in V2O3 are considered archetypal manifestations of Mott physics. Despite decades of research, the effects of doping, pressure, and anisotropic strains on the transitions are still debated. To understand how these parameters control the transitions, anisotropically strained pure V2O3 films are explored with nearly the same contraction along the c‐axis, but different degrees of ab‐plane expansion. With small ab‐plane expansion, the films behave similar to bulk V2O3 under hydrostatic pressure. However, with large ab‐plane expansion, the films are driven into the “negative pressure” regime, similar to that of Cr‐doped V2O3, exhibiting clear coexistence of paramagnetic insulator and paramagnetic metal phases between 180–500 K. This shows that c‐axis contraction alone, or an increase in c/a ratio is insufficient for inducing “negative pressure” effects. Actually, c‐axis contraction alone destabilizes the two insulating phases of V2O3, whereas a‐axis expansion tends to stabilize them. The effects of strain are modeled using density functional theory providing good agreement with experimental results. The findings show that chemical pressure alone cannot account for the phase diagram of (V1−xCrx)2O3. This work enables to manipulate a Mott transition above room temperature, thereby expanding the opportunities for applications of V2O3 in novel electronics.

In Situ Stress Determination Based on Acoustic Image Logs and Borehole Measurements in the In-Adaoui and Bourarhat Hydrocarbon Fields, Eastern Algeria

The study of in situ stress from image logs is a key factor for understanding regional stresses and the exploitation of hydrocarbon resources. This work presents a comprehensive geomechanical analysis of two eastern Algerian hydrocarbon fields to infer the magnitudes of principal stress components and stress field orientation. Acoustic image logs and borehole measurements were used in this research to aid our understanding of regional stress and field development. The studied In-Adaoui and Bourarhat fields encompass a combined thickness of 3050 m of Paleozoic and Mesozoic stratigraphy, with the primary reservoir facies in the Ordovician interval. The Ordovician sandstone reservoir interval indicates an average Poisson’s ratio (v) of 0.3, 100–150 MPa UCS, and 27–52 GPa Young’s modulus (E). Direct formation pressure measurements indicate that the sandstone reservoir is in a hydrostatic pore pressure regime. Density-derived vertical stress had a 1.1 PSI/feet gradient. Minimum horizontal stress modeled from both Poisson’s ratio and an effective stress ratio-based approach yielded an average 0.82 PSI/feet gradient, as validated with the leak-off test data. Drilling-induced tensile fractures (DITF) and compressive failures, i.e., breakouts (BO), were identified from acoustic image logs. On the basis of the DITF criterion, the maximum horizontal stress gradient was found to be 1.57–1.71 PSI/feet, while the BO width-derived gradient was 1.27–1.37 PSI/feet. Relative stress magnitudes indicate a strike-slip stress regime. A mean SHMax orientation of N130°E (NW-SE) was interpreted from the wellbore failures, classified as B-quality stress indicators following the World Stress Map (WSM) ranking scheme. The inferred stress magnitude and orientation were in agreement with the regional trend of the western Mediterranean region and provide a basis for field development and hydraulic fracturing in the low-permeable reservoir. On the basis of the geomechanical assessments, drilling and reservoir development strategies are discussed, and optimization opportunities are identified.

Lab-scale ballistic and safety property investigations of LMP-103S

LMP-103S is a storable, green, ammonium dinitramide (ADN)-based liquid monopropellant with significant potential owing to its improved specific impulse (≥ 6%) and density (∼24%) in comparison to hydrazine, and its superior safety and handling characteristics. LMP-103S already has a significant history of thruster testing and flight heritage. However, its baseline combustion behavior is a surprisingly understudied topic. Constant-volume strand burner experiments with LMP-103S are reported herein for pressures between 0.69 and 34.5 MPa (100 – 5,000 psia). Linear burning rates were measured from transient pressure data and high-speed video. Visible and near-IR emission spectra were recorded as well. Phenomenological combustion behaviors are reported for the entire pressure range as deduced from these diagnostics, and two clear pressure regimes are observed. Hydrodynamic instabilities and supercritical combustion processes dominate the combustion behavior in the low- and high-pressure regimes, respectively. Supporting experiments include thermal cook-off of LMP-103S and impact sensitivity testing of ADN crystals extracted from LMP-103S solution. The data presented herein significantly expand upon those available in the literature for LMP-103S, and the phenomenological combustion behavior deduced from transient, high-speed video data improve upon the state-of-the-art knowledge regarding ADN-based liquid monopropellants.