Operating Regimes Research Articles

Improved thermal stability and electrical conductivity of dysprosium doped barium zirconium cerate electrolyte

Acceptor-doped perovskites based on the BaCeO3 have been extensively investigated as promising candidates for proton-conducting electrolyte at intermediate temperatures. This operational regime is characterized by proton conduction facilitated via hydroxyl protons that effectively occupy vacancies of oxide ions within the perovskite crystal lattice structure. While the trade-off parameters (proton conductivity and chemical stability) concern the utility of cerium-based electrolytes, acceptor doped compounds hinder the mobility of protons due to dopant-charge and dopant-host interactions. However, Dy-doped compounds reveal a promising behavior relative to most acceptor substituents with marginal constraints at higher doping concentration. As a result, a threshold doping range is essential to combat material inconsistencies such as cationic disorder to proton trapping effect. Therefore in the present study we synthesize the single-phase dysprosium and zirconium co-doped barium cerate at different doping concentrations (BaCe0.8-xZr0.2DyxO3-δ (x = 0.0–0.20)) to showcase the chemical inertness of the compound against oxidizing and reducing atmospheres preserving high ionic conductivity. According to our experimental outcomes, higher ionic conductivity among wet atmospheric conditions suggests the role of moisture to contribute additional charge carriers among the Dy-doped samples via explicitly generated oxygen vacancies. As a result, BaCe0.65Zr0.2Dy0.15O3-δ demonstrates a highest total conductivity, reaching 2.44 x 10-2 S cm−1 at 575 °C, with an associated activation energy of 0.61 eV within the temperature range of 300–600 °C. The study also reveals the optimal operating temperature of the proton conducting electrolyte to avoid mixed ionic (H+ and O2–) conduction.

A two-sided equilibrium model of Vehicle-to-Vehicle charging platform

A novel mobile charging service utilizing vehicle-to-vehicle (V2V) charging technology has been proposed as a complement to fixed charging infrastructure (CI), enabling electric vehicles (EVs) to exchange electricity. This study develops a two-sided equilibrium model for a V2V charging platform, where the demand-side charging vehicles (CVs) choose between charging piles and the V2V platform, and the supple-side discharging vehicles (DVs) decide whether to provide discharging services. The V2V platform matches CVs with DVs, receiving compensation from CV owners and reimbursing DV owners. To explore the strategic interactions between the V2V platform and fixed CI operators, we construct an analytical bi-level model that examines different operation regimes, including competitive and cooperative scenarios, i.e., non-cooperative game and Nash Bargaining game. The lower-level model is a two-sided equilibrium model that quantifies charging and discharging choices of EV owners, while the upper-level model optimizes the pricing decisions of the V2V platform and fixed CI operator. Numerical results indicate that the introduction of the V2V platform can reduce the overall charging costs, thus encourage the use of public charging services. Furthermore, it is suggested that the V2V platform be managed by independent enterprises, rather than existing fixed CI operators, to promote the EVs at relatively low charging costs.

MHD stability trends and improved performance of LHD inward-shifted configurations: The role of the neutral beam current drive and thermal plasma density

The aim of the present study is to analyze the effect of the neutral beam current drive (NBCD), thermal plasma density, and NBI operational regime on the stability of pressure gradient-driven modes (PGDM) and Alfvén eigenmodes (AE) in LHD inward-shifted configurations. The stabilization of n/m=1/2 PGDM (n toroidal mode and m poloidal mode) is observed in the discharge 167 800 during the co-NBCD phase. The iota profile evolution measured by motional stark effect diagnostic may indicate the iota profile up-shift caused by the co-NBCD can induce a non-resonant transition of the rational surface 1/2 before the mode stabilization. The evolution of the iota profile and continuum gaps in the discharge 167 805 during the ctr-NBCD phase leads to the stabilization of the AE, caused by the narrowing of the continuum gap as the iota profile down-shift. Opposite stability trends are identified for PGDM and AE stability with respect to the thermal plasma density. A larger thermal plasma density (larger thermal β) further enhances PGDM although the continuum gaps are narrower leading to configurations with stable AEs. The linear stability of AEs is analyzed using the gyro-fluid FAR3d code to reproduce the AE stability trends observed in the experiments with respect to the NBCD and thermal plasma density. The analysis of hypothetical scenarios dedicated to study different NBI operational regimes with respect to EP energy, and β and radial density profiles indicate off-axis NBI operation shows a higher EP β threshold to destabilize AEs compared to on-axis configuration. This is explained by the presence of a TAE gap in the inner plasma region, easily destabilized by an on-axis NBI injection. The control of the NBCD and thermal plasma in the discharge 167 800 shows a transitory stabilization of PGDM and AEs, as well as an improved discharge performance identified by an increment of the neutron fluxes.

Compact modeling of short-channel effects in back-gated 2D negative capacitance (NC) FETs

The negative capacitance field-effect transistor with 2D channel material (2D NC-FET) holds significant promise for low-power applications owing to its remarkable resilience against short-channel effects (SCEs) and favorable noise characteristics. In this study, we establish a compact current–voltage (I–V) model for short-channel back-gated 2D NC-FETs with metal-ferroelectric-metal–insulator–semiconductor structure by self-consistently solving the two-dimensional Poisson, drift–diffusion and Landau–Khalatnikov equations. The proposed model is valid and continuous throughout the entire operating regime, including the fully-depleted region, partly-depleted region, and accumulation region. Furthermore, we derive analytical equations for the threshold voltage ( VTH ) and subthreshold swing ( SS ) of back-gated 2D NC-FETs based on the developed I–V model. Lastly, we elucidate the influence mechanisms of various device parameters and voltage bias on the subthreshold characteristics of short-channel back-gated 2D NC-FETs using the proposed I–V model in conjunction with analytical expressions of VTH and SS . Our findings reveal that back-gated 2D NC-FETs shows unconventional degradation behavior in VTH and SS, resulting from the competition between traditional SCEs and novel negative capacitance effects.

Voltage-controlled nonlinear optical properties in gold nanofilms via electrothermal effect

Dynamic control of the optical properties of gold nanostructures is crucial for advancing photonics technologies spanning optical signal processing, on-chip light sources and optical computing. Despite recent advances in tunable plasmons in gold nanostructures, most studies are limited to the linear or static regime, leaving the dynamic manipulation of nonlinear optical properties unexplored. This study demonstrates the voltage-controlled Kerr nonlinear optical response of gold nanofilms via the electrothermal effect. By applying relatively low voltages (~10 V), the nonlinear absorption coefficient and refractive index are reduced by 40.4% and 33.1%, respectively, due to the increased damping coefficient of gold nanofilm. Furthermore, a voltage-controlled all-fiber gold nanofilm saturable absorber is fabricated and used in mode-locked fiber lasers, enabling reversible wavelength-tuning and operation regimes switching (e.g., mode-locking—Q-switched mode-locking). These findings advance the understanding of electrically controlled nonlinear optical responses in gold nanofilms and offer a flexible approach for controlling fiber laser operations.

Comprehensive assessment of blood–brain barrier opening and sterile inflammatory response: unraveling the therapeutic window

Microbubbles (MBs) combined with focused ultrasound (FUS) has emerged as a promising noninvasive technique to permeabilize the blood–brain barrier (BBB) for drug delivery into the brain. However, the safety and biological consequences of BBB opening (BBBO) remain incompletely understood. This study aims to investigate the effects of two parameters mediating BBBO: microbubble volume dose (MVD) and mechanical index (MI). High-resolution MRI-guided FUS was employed in mouse brains to assess BBBO by manipulating these two parameters. Afterward, the sterile inflammatory response (SIR) was studied 6 h post-FUS treatment. Results demonstrated that both MVD and MI significantly influenced the extent of BBBO, with higher MVD and MI leading to increased permeability. Moreover, RNA sequencing revealed upregulation of major inflammatory pathways and immune cell infiltration after BBBO, indicating the presence and extent of SIR. Gene set enrichment analysis identified 12 gene sets associated with inflammatory responses that were significantly upregulated at higher MVD or MI. A therapeutic window was established between therapeutically relevant BBBO and the onset of SIR, providing operating regimes to avoid damage from stimulation of the NFκB pathway via TNFɑ signaling to apoptosis. These results contribute to the optimization and standardization of BBB opening parameters for safe and effective drug delivery to the brain and further elucidate the underlying molecular mechanisms driving sterile inflammation.

Operation regimes of spinal circuits controlling locomotion and role of supraspinal drives and sensory feedback.

Locomotion in mammals is directly controlled by the spinal neuronal network, operating under the control of supraspinal signals and somatosensory feedback that interact with each other. However, the functional architecture of the spinal locomotor network, its operation regimes, and the role of supraspinal and sensory feedback in different locomotor behaviors, including at different speeds, remain unclear. We developed a computational model of spinal locomotor circuits receiving supraspinal drives and limb sensory feedback that could reproduce multiple experimental data obtained in intact and spinal-transected cats during tied-belt and split-belt treadmill locomotion. We provide evidence that the spinal locomotor network operates in different regimes depending on locomotor speed. In an intact system, at slow speeds (< 0.4 m/s), the spinal network operates in a non-oscillating state-machine regime and requires sensory feedback or external inputs for phase transitions. Removing sensory feedback related to limb extension prevents locomotor oscillations at slow speeds. With increasing speed and supraspinal drives, the spinal network switches to a flexor-driven oscillatory regime and then to a classical half-center regime. Following spinal transection, the model predicts that the spinal network can only operate in the state-machine regime. Our results suggest that the spinal network operates in different regimes for slow exploratory and fast escape locomotor behaviors, making use of different control mechanisms.

The Cost of Impatience in Dynamic Matching: Scaling Laws and Operating Regimes

We study matching queues with abandonment. The simplest of these is the two-sided queue with servers on one side and customers on the other, both arriving dynamically over time and abandoning if not matched by the time their patience elapses. We identify nonasymptotic and universal scaling laws for the matching loss due to abandonment, which we refer to as the “cost of impatience.” The scaling laws characterize the way in which this cost depends on the arrival rates and the (possibly different) mean patience of servers and customers. Our characterization reveals four operating regimes identified by an operational measure of patience that brings together mean patience and utilization. The four regimes subsume the regimes that arise in asymptotic (heavy-traffic) approximations. The scaling laws, specialized to each regime, reveal the fundamental structure of the cost of impatience and show that its order of magnitude is fully determined by (i) a “winner-take-all” competition between customer impatience and utilization, and (ii) the ability to accumulate inventory on the server side. Practically important is that when servers are impatient, the cost of impatience is, up to an order of magnitude, given by an insightful expression where only the minimum of the two patience rates appears. Considering the trade-off between abandonment and capacity costs, we characterize the scaling of the optimal safety capacity as a function of costs, arrival rates, and patience parameters. We prove that the ability to hold inventory of servers means that the optimal safety capacity grows logarithmically in abandonment cost and, in turn, slower than the square-root growth in the single-sided queue. This paper was accepted by Baris Ata, stochastic models and simulation. Supplemental Material: The online appendix and data files are available at https://doi.org/10.1287/mnsc.2023.01513 .

A Clean and Health-Care-Focused Way to Reduce Indoor Airborne Bacteria in Calf House with Long-Wave Ultraviolet.

Long-term exposure to a relatively high concentration of airborne bacteria emitted from intensive livestock houses could potentially threaten the health and welfare of animals and workers. There is a dual effect of air sterilization and promotion of vitamin D synthesis for the specific bands of ultraviolet light. This study investigated the potential use of A-band ultraviolet (UVA) tubes as a clean and safe way of reducing airborne bacteria and improving calf health. The composition and emission characteristics of airborne bacteria were investigated and used to determine the correct operating regime of UVA tubes in calf houses. Intermittent exceedances of indoor airborne bacteria were observed in closed calf houses. The measured emission intensity of airborne bacteria was 1.13 ± 0.09 × 107 CFU h-1 per calf. Proteobacteria were the dominant microbial species in the air inside and outside calf houses. After UVA radiation, the indoor culturable airborne bacteria decreased in all particle size ranges of the Anderson sampler, and it showed the highest reduction rate in the size range of 3.3-4.7 μm. The results of this study would enrich the knowledge of the source characteristics of the airborne bacteria in intensive livestock farming and contribute to the environmental control of cattle in intensive livestock production.

Determination of operational flow regime and heat transfer performance optimization of mono and hybrid nanofluids using FOM and sensitivity analysis

Nanofluids are considered as the most suitable replacement for conventional coolants due to their augmented thermal properties. The current study focuses on the operational suitability of different nanofluids (45 nanofluids) and estimates their heat transfer performance through Figure of merit (FOM) analysis. To perform an FOM-based ranking of these nanofluids, the heat transfer coefficient, friction factor, and pumping power of several nanofluids were also calculated. The effect of varying the volumetric concentration (0.01–1 vol%) on the pumping power, heat transfer coefficient, and thermo-physical characteristics of several nanofluids was examined. Different process and design parameters like pressure drop, flow velocity, mass flow rate, internal channel diameter, fluid temperature gradient, and wall temperature of the system were varied to check their effect on heat transfer coefficient, friction factor, and pumping power. Based on the FOM analysis, the authors determined that the majority of the nanofluids (26 nanofluids) investigated can be used in both laminar and turbulent flow regimes. The heat transfer coefficient decreases with increasing nanoparticle concentration. Therefore, it is essential to keep the concentration at an optimum level to attain the desired heat transfer performance. Among various key findings from the study, authors reported that the friction factor and pumping power of the nanofluid increases when the pressure drops and the channel’s internal diameter increases, while with increasing flow velocity, the friction factor and pumping power decrease. The authors also suggest that the pressure drop should be limited to 1–1.003 bar, the flow velocity should be greater than 1.4–1.5 m/s and the internal diameter should be 0.02 m to maintain the friction factor below 0.1. The aforementioned parameters are crucial when optimizing the heat transfer performance of a cooling system using nanofluid as a coolant.

Стабілізація обертання ротора Дар'є сумісними змінами довжини лопатей і траверс

With the ever-increasing prices of and demand for traditional fuels and the decreasing availability thereof, renewable energy sources, such as wind energy, are gaining enormous popularity. First of all, this branch of "green" energy is environmentally friendly. A significant increase in the use of wind power plants (WPPs) is observed all over the world. Modern WPPs are of two types: vertical- and horizontal-axis ones. Vertical-axis WPPs, in contrast to horizontal-axis ones, have a number of specific design advantages, such as, for example, insensitivity to the wind direction, which significantly simplify their design and increase their reliability. The operation of vertical-axis WPPs involves the need to stabilize their operating regimes, the main objective of which is to stabilize electricity production in conditions of a variable wind speed using appropriate stabilization systems (SSs). In SS development, use is made of various control algorithms, which make a basis for harnessing physical principles of SS construction. Recently, SSs based on blade swept area variation have become widespread. Such systems, unlike systems based on, for example, generator load variation, actually use the adaptation of WPPs to a variable wind speed, and they dispense with the need for mechanical dissipation of excess energy by resistance forces and, to some extent, with the need to transfer it to the support. The last point significantly reduces the load on the rotor-to-generator transmission systems and alleviates the requirements for anchor systems in the case of WPPs installed on floating platforms. In terms of design, the stabilization of vertical-axis WPPs by swept area variation can be performed in three ways: by varying the blade length, varying the length of the traverses whereby the blades are attached to the rotor shaft, and by simultaneously varying the length of the blades and the traverses, i.e., by varying WPP rotor configuration. The elaboration of approaches to the development of algorithms for the stabilization of vertical-axis WPPs controlled by rotor configuration variation is an important and promising task. The goal of this paper is to develop efficient algorithms for stabilizing the variable-configuration WPP rotor speed providing the stability and operability of the channels of blade and traverse length variation in their simultaneous operation. The problem is solved using methods of the classical theory of automatic control and mathematical simulation. The novelty lies in extending the concept of control by swept area variation to Darrieus vertical-axis WPPs, synthesizing efficient algorithms for stabilizing the rotor speed of Darrieus vertical-axis WPPs controlled by rotor configuration variation, and determining conditions for their stability and operability. The algorithms and approach developed may be used in substantiating design solutions for Darrieus vertical-axis WPPs.

Controlling the spectral persistence of a random laser

Random lasers represent a relatively undemanding technology for generating laser radiation that displays unique characteristics of interest in sensing and imaging. Furthermore, they combine the classical laser’s nonlinear response with a naturally occurring multimode character and easy fabrication, explaining why they have been recently proposed as ideal elements for complex networks. The typical configuration of a random laser consists of a disordered distribution of scattering centers spatially mixed into the gain medium. When optically pumped, these devices exhibit spectral fluctuations from pulse to pulse or constant spectra, depending on the pumping conditions and sample properties. Here, we show clear experimental evidence of the transition from fluctuating (uncorrelated) to persistent random laser spectra, in devices in which the gain material is spatially separated from the scattering centers. We interpret these two regimes of operation in terms of the number of cavity round trips fitting in the pulse duration. Only if the cavity round-trip time is much smaller than the pulse duration are modes allowed to interact, compete for gain, and build a persisting spectrum. Surprisingly this persistence is achieved if the pumping pulse is long enough for radiation in the cavity to perform some 10 round trips. Coupled-mode theory simulations support the hypothesis. These results suggest an easy yet robust way to control mode stability in random lasers and open the pathway for miniaturized systems, as, for example, signal processing in complex random laser networks.

The Influence of Pump-Turbine Specific Speed on Hydraulic Transient Processes

The main porpose of this paper is to perform and present at transient process analysis on the influence of different specific speeds (nq) of the three-model pump-turbines that may implemented at the hydropower pump storage plant (HPSP) Bajina Basta, Serbia. The intention is to analyze the operation regimes along the S-shaped characteristic curve, which creates difficulties in calculations during the load-rejection process. These problems are manifested by an unusual increase in water pressure, followed by an increase in machine vibrations, thus threatening the stability of machine operation. The subject of this research is the four-quadrant (4Q) characteristic curves, presented in the form of Suter curves (the head and momentum parameters (Wh and Wm), in dependence of angle (θ)) for different wicket gate openings, of the three pump-turbine models with different specific speeds (nq = 27, nq = 38 and nq = 50). These 4Q characteristics are used as input data for numerical code developed to calculate the simultaneous load rejection of both pump-turbines. The numerical code is based on the method of characteristics and applied to the test case at HPSP. This is especially relevant when dealing with characteristic S-shaped curves that may lead to serious instability in operation during the transient process. The calculation results show changes in the pressure, speed of rotation and discharge of the machine operation regimes, but the important findings are reflected in further application of the results to determine the parametric flow and speed (Q11 and n11) trajectories of the operating points, where the unstable behavior of a pump-turbine operating in turbine mode is presented and periodically the trajectories also pass through the reverse pump zone.

A dynamically equivalent atomistic electrochemical paradigm for the larger-scale experiments.

Electrochemical systems possess a considerable part of modern technologies, such as the operation of rechargeable batteries and the fabrication of electronic components, which are explored both experimentally and computationally. The largest gap between the experimental observations and atomic-level simulations is their orders-of-magnitude scale difference. While the largest computationally affordable scale of the atomic-level computations is ∼ns and ∼nm, the smallest reachable scale in the typical experiments, using very high-precision devices, is ∼s and ∼μm. In order to close this gap and correlate the studies in the two scales, we establish an equivalent simulation setup for the given general experiment, which excludes the microstructure effects (i.e., solid-electrolyte interface), using the coarse-grained framework. The developed equivalent paradigm constitutes the adjusted values for the equivalent length scale (i.e., lEQ), diffusivity (i.e., DEQ), and voltage (i.e., VEQ). The time scale for the formation and relaxation of the concentration gradients in the vicinity of the electrode matches for both smaller scale (i.e., atomistic) equivalent simulations and the larger scale (i.e., continuum) experiments and could be utilized for exploring the cluster-level inter-ionic events that occur during the extended time periods. The developed model could offer insights for forecasting experiment dynamics and estimating the transition period to the steady-state regime of operation.

Superluminal light propagation in a three-level ladder system

Superluminal light propagation is typically accompanied by significant absorption that might prevent its observation in realistic samples. We propose an all-optical implementation exploiting the two-photon resonance in three-level media to overcome this problem. With several computational methods, we analyze three possible configurations of optically-dressed systems and identify an optimal configuration for superluminal propagation. Due to the far-detuned operating regime with low absorption, this scenario avoids the usual need for population inversion, gain assistance or nonlinear optical response. Our analysis covers a broad parameter space and aims for the identification of conditions where significant pulse advancement can be achieved at high transmission levels. In this context, a figure of merit is introduced accounting for a trade-off between the desired group-index values and transmission level. This quantity helps to identify the optimal characteristics of the dressing beam.

Performance and Emission Characterization of a High-Injection Pressure Common Rail Diesel Engine Fueled by Blended Diesel and TiO2 Nanoparticles.

Abstract How to increase engine power and reduce fuel consumption and emission is an important target that engine designers try to achieve it. One of the most promising approaches to realise this goal is adding nano additives to fuel. Titanium dioxide (TiO2) blended with biofuels get wide studies by researchers using conventional diesel engines at different operating regimes. This work aims to prolong these investigations using diesel fuel, rather than biofuels, on a high injection pressure (1400 – 1600 bar) common rail diesel engine at wide operating conditions and different TiO2 concentrations. Experimental outcomes show an increase in peak cylinder pressure up to 8.51% than pure diesel when using 100 ppm TiO2 concentration. Also, BSFC has been decreased by 36%, and BTE increased by 48% compared to pure diesel at high speeds and loads. NOx and CO2 emissions raised by 35.3% and 40.3% respectively, while CO emissions decreased by 35%. These results could be a reason for further studies for TiO2 using different sizes, at wider engine regimes and mixture strengths.

Problems of Countering Terrorism in the Decisions of the Constitutional Court of the Russian Federation

The paper elucidates the problems related to various aspects of counter-terrorism activities in Russia. This activity involves the use of a set of political, socio-economic, information and propaganda, legal, special and other measures, the possibility of introducing a legal regime for a counter-terrorism operation, as well as ensuring the restoration of the rights of persons affected by the actions of terrorists. The author examines the content of the legal standing of the Constitutional Court of the Russian Federation concerning the forms and methods of antiterrorist activities, including the criteria for evaluating the legal restrictions applied in this case, their admissibility and proportionality. Special attention is paid to constitutionally significant aspects of the consideration of criminal cases on terrorism, problems of anti-terrorist protection of transport and other infrastructure facilities, issues of social protection of military personnel, law enforcement officers and other persons engaged in countering terrorism. The author explains the significance of the legal standings defined by the Constitutional Court of the Russian Federation, the nature of their impact on law-making and law enforcement activities in the area under consideration.

Theoretical analysis of passively mode-locked semiconductor ring lasers.

In this paper, the theoretical analysis of the passive mode-locked semiconductor ring lasers (PML-SRLs) is investigated based on a travelling wave model. It is found that both the optical confinement factor and the injection current make great contributions to the operation regime and the performance of PML-SRLs. All operation regimes of PML-SRLs are governed by the transient gain-loss balance. Such balance is closely associated with the relationship among the stimulated rate in the semiconductor optical amplifier (SOA), the carrier lifetime in the saturated absorber (SA), and the roundtrip time of the ring resonator. Furthermore, our investigation indicates that the mode-locked state of such PML-SRLs is independent of the passive waveguide, but the performance degrades with the increased waveguide loss or the shortened waveguide length, once the material bandwidth is wide enough. Another discovery is that it is possible to achieve the high energy pulse in the PML-SRL with shortening the passive length and narrowing the gain spectrum meanwhile. Overall, such investigations should benefit designing the required PML-SRLs and achieving the high performance.

Highly efficient solid-state vortex laser in a robust and simple configuration.

Vortex beams, known as a typical form of structured light, possess numerous applications in various fields. Their widespread application prospects have then sparked an in-depth analysis of the generation and manipulation of vortex modes in an active cavity, as well as the development of high-performance vortex lasers. In this paper, we report on a new class of highly efficient and high-power Nd:YAG vortex lasers in a robust and compact configuration, which allows direct generation of vortex beams with an easily controllable topological charge both in the continuous-wave and pulsed operation regimes. The on-demand generation of intracavity vortex modes is realized based on a Q-plate by controlling the geometric phase inside the laser resonator. The maximum output power in the continuous-wave regime is 4.11 W with a slope efficiency of 37.9%. Besides, the vortex pulses are also achieved by including a Cr:YAG crystal in the cavity as a saturable absorber. The shortest pulse width is 142.8 ns at a pulse repetition rate of 232.6 kHz, with a maximum average output power of 1.05 W. Vortex modes with other topological charges can be obtained by simply changing the corresponding Q-plate without sacrificing the lasing efficiency. The experimental results can shed some light on the design and building of highly efficient and high-power vortex lasers together with a well-defined controllable topological charge, aiming at some specific applications.

A Review of Coupled Geochemical–Geomechanical Impacts in Subsurface CO2, H2, and Air Storage Systems

Increased demand for decarbonization and renewable energy has led to increasing interest in engineered subsurface storage systems for large-scale carbon reduction and energy storage. In these applications, a working fluid (CO2, H2, air, etc.) is injected into a deep formation for permanent sequestration or seasonal energy storage. The heterogeneous nature of the porous formation and the fluid–rock interactions introduce complexity and uncertainty in the fate of the injected component and host formations in these applications. Interactions between the working gas, native brine, and formation mineralogy must be adequately assessed to evaluate the efficiency, risk, and viability of a particular storage site and operational regime. This study reviews the current state of knowledge about coupled geochemical–geomechanical impacts in geologic carbon sequestration (GCS), underground hydrogen storage (UHS), and compressed air energy storage (CAES) systems involving the injection of CO2, H2, and air. Specific review topics include (1) existing injection induced geochemical reactions in these systems; (2) the impact of these reactions on the porosity and permeability of host formation; (3) the impact of these reactions on the mechanical properties of host formation; and (4) the investigation of geochemical-geomechanical process in pilot scale GCS. This study helps to facilitate an understanding of the potential geochemical–geomechanical risks involved in different subsurface energy storage systems and highlights future research needs.