Search Results (688)

Block 116 has an annual oil production of 10.2 × 10⁴ t, yet the increasing edge-water encroachment has raised the natural decline rate from 7.8% to 11.4%, significantly deteriorating production performance. The field data shows an edge-water rise rate of 0.4 m/a. Since 2023, 11 flank wells have experienced water breakthrough, resulting in a daily loss of 12.6 t and contributing 4.6% to the overall decline. To address these challenges, this study systematically evaluates development characteristics, identifies key influencing factors, and establishes optimal injection–production parameters through an integrated experimental and numerical approach. The research results show that a novel combined flooding formulation—water + foaming agent + polymer (viscoelastic) + N₂—is proposed and validated, achieving the highest recovery efficiency of 63.09%, which is 22.99% higher than conventional waterflooding. This confirms that switching to a multimedium injection strategy at mid- to high-water-cut stages can substantially improve ultimate recovery. Numerical simulation quantitatively delineates the remaining oil distribution across individual sublayers, revealing that residual recoverable reserves (76.6 × 10⁴ t) are predominantly concentrated in five specific sand bodies, providing precise targets for infill drilling. A comprehensive field-scale adjustment strategy is formulated—integrating optimized technical policies, planar and vertical injection–production improvements, and coordinated end-to-end management—which, over the 15-year forecast period, is projected to increase cumulative oil output from 149.4 × 10⁴ t to 168.1 × 10⁴ t, raising the recovery factor by 3.3%. These findings offer both theoretical insights and practical guidance for sidetracking and effective reserve utilization in analogous low-permeability reservoirs within the Changqing Oilfield and beyond. Full article

Introduction: Sarcopenia and frailty are emerging independent risk factors for cardiovascular disease. Sarcopenia represents a decline in function associated with reduced muscle mass. Frailty, defined as a phenotype or the multiple stress model, is associated with weakness and a decline in organ reserve with vulnerability to disease. Frailty and sarcopenia may overlap and have shared clinical risk factors including age and malnutrition. Methods: We performed a literature review of published studies on frailty and sarcopenia with respect to cardiovascular risk factors and body composition. Results: Studies demonstrated that obese sarcopenic or obese frail subjects had a higher prevalence of cardiovascular risk factors such as hypertension, diabetes mellitus, dyslipidaemia, smoking and sedentary lifestyle, which was highly associated with cardiovascular disease. On the other hand, anorexic malnourished frail participants with unintentional weight loss or sarcopenic subjects without obesity had a low prevalence of cardiovascular risk factors, which was less associated with cardiovascular disease. Conclusions: Obesity appears to play a crucial role in mediating the cardiovascular risk of both sarcopenic and frail patients. Full article

As modern electricity system evolve toward smart grids, increasing technological and regulatory complexity makes distribution system planning a challenging task. This paper develops new planning and reliability models to help local distribution companies (LDCs) achieve cost-effective, reliable solutions amid these changes. Furthermore, this paper offers a novel iteration-based optimization model incorporating reliability and security considerations. Also, this work proposes the concept of virtual microgrids to enhance distributed generation (DG) penetration in weak areas, thereby improving reliability where it is most needed. The proposed model reduces an LDC’s total planning cost covering substation and feeder upgrades, market energy purchases, payments to DG owners, energy losses, and operations while ensuring that reliability indices and energy not supplied stay within regulatory limits. To ensure compliance with operational security limits as DG penetration rises, the DG capacity is split into normal operating capacity and reserve capacity. The results confirm the proposed algorithm’s superiority relative to current state-of-the-art planning methodologies. Full article

Extreme droughts can rapidly reshape surface-water patterns in river-connected floodplain wetlands, yet the fine-scale responses of individual dish-shaped sub-lakes remain insufficiently resolved. This study focused on the 2022 extreme drought in Poyang Lake, China’s largest freshwater lake and a globally important floodplain wetland system. The objectives were to quantify wetland landscape changes during the 2022 extreme drought event and to compare the heterogeneous responses of dish-shaped sub-lakes under contrasting surface-water linkage and management-context settings. We developed a high-resolution wetland monitoring framework on the Google Earth Engine platform by integrating Sentinel-2 multispectral imagery, Sentinel-1 synthetic-aperture radar, and the Dynamic World land-cover product. This multi-source approach was designed to reduce spectral confusion among turbid water, saturated mudflats, and exposed lakebeds during extreme low-water stages. Monthly wetland maps were generated for the Poyang Lake National Nature Reserve and compared with a five-year historical baseline from 2017 to 2021. The framework achieved an overall accuracy of 87.44%, with a Kappa coefficient of 0.80. The results revealed a rapid wet-to-dry transition in 2022. The water area contracted by 78.1% from July to September and remained 73.6–74.7% below the historical baseline from September to November. This contraction was accompanied by extensive observable surface-water fragmentation, apparent loss of visible surface-water linkage among sub-lakes, and substantial wetland habitat contraction. Sub-lakes exhibited clearly differentiated drought responses. Sub-lakes with stronger visible surface-water linkage to the main lake generally experienced more rapid water loss during recession, whereas reserve-managed or facility-present sub-lakes retained residual water to varying degrees and may have provided important refugial habitats for waterbirds and aquatic species. These findings suggest that surface-water linkage condition, local topographic setting, and 2022 management context were jointly associated with the heterogeneous drought responses of sub-lakes. The proposed framework provides a tool for monitoring wetland landscape changes associated with extreme drought events, assessing ecological vulnerability, and supporting adaptive water-level management under intensifying climate extremes. Full article

Direct current (DC) bus voltage stability in grid-connected microgrids with multiple energy-storage converter branches is governed by the coupled dynamics of photovoltaic generation, heterogeneous battery storage, and the grid-connected inverter. Conventional independent and droop control methods allocate branch power mainly from local voltage or state-of-charge information, and therefore cannot fully account for converter limits, battery condition, or inverter current admissibility. This paper proposes a constraint-aware predictive energy coordination (CAPEC) method for DC bus stabilization. A DC bus energy model with variable losses is combined with one-step disturbance prediction and a safety governor that allocates storage power according to state of charge (SOC), state of health (SOH), power reserve, thermal margin, current capability, and ramp limits. The grid-connected inverter is treated as a constrained energy regulation path with active power saturation and antiwindup correction. Small-signal and energy function analyses show that CAPEC increases equivalent DC bus damping and yields bounded voltage recovery for feasible references and bounded prediction errors. MATLAB R2023b studies for combined photovoltaic and load variation, grid interface disturbance, and heterogeneous storage conditions show that CAPEC limits the maximum voltage deviation to 2.86 to 6.35 V. A reduced power laboratory experiment further verifies the Case B breaker disturbance and confirms stable DC bus behavior during unplanned grid interface switching. Full article

Variable-speed induction motor drives spend most of their service life at partial load, where rated-flux field-oriented control (FOC) is inefficient and where loss-minimizing control (LMC) recovers a large part of the loss. LMC, however, is brittle in two ways that matter in industry: it is tuned isothermally, so as the windings heat, the rotor-resistance drift detunes the field orientation and corrupts torque; and it treats the loss-optimal flux as a quasi-static set-point, so an abrupt load rise from a light-load, low-flux condition forces a slow flux rebuild that throttles torque. This paper proposes a thermally adaptive economic model predictive controller (TA-EMPC) that retains the energy optimum of LMC while removing both weaknesses. A temperature-coupled total-loss model (machine copper and core loss plus inverter conduction and switching loss) is minimized over a finite horizon subject to a torque-delivery constraint; a reduced-order two-node thermal observer updates the loss-defining resistances online without a temperature sensor; and a load-demand-aware flux-reservation term pre-magnetizes the machine ahead of anticipated torque rises. In simulations on a representative 7.5 kW drive, TA-EMPC matched the energy of static LMC to within 0.3% across pump, conveyor, and fast-cycling duty profiles—both saving 1.4–2.3% of cycle energy relative to rated-flux FOC, and up to about 14.7 efficiency points at very light load—while, unlike LMC, holding the steady torque error below 0.5% when the winding temperature rose by about 95 °C, to a hot steady state near 115 °C (a stator-resistance increase of roughly 37%) (against an 8% error for the non-adaptive scheme) and reducing the torque undershoot during a light-to-heavy load step from about 23% to near zero. All quantitative results reported in this work are obtained entirely in simulation. A per-step operation-count analysis—not an on-target timing measurement—indicates that the condensed quadratic-program formulation with move blocking is executable within the 100 µs sampling interval on a production digital signal controller for the chosen control horizon; experimental validation on a loaded dynamometer bench, together with on-target timing measurement, is identified as future work. The contribution is thus energy-efficient operation delivered with the torque robustness that loss minimization alone does not provide. Full article

An excavation-induced clayey landslide in Jianshui County, Yunnan Province, China, threatens a national refined oil pipeline near the rear slope. Field investigation, borehole logging, laboratory testing, and three-dimensional finite-element analyses were integrated to investigate the excavation–rainstorm instability mechanism and evaluate circular anti-slide piles with toe backfilling. Under natural excavation, the reported factor of safety was 1.39, and the maximum displacement was 2.35 mm. Under a 60 mm/day rainstorm, increased pore-water pressure and saturation in the shallow sliding mass and strongly weathered claystone, together with saturated-state strength parameters, reduced the shear-strength reserve. The deformation and stability analyses yielded a maximum computed displacement of 1.36 m and a factor of safety of 0.95, respectively, indicating pronounced pre-failure deformation and loss of stability. After mitigation, the factor of safety increased to 1.41, while the maximum slope and pile-head displacements were both approximately 6.90 mm. The pile row redistributed nonuniform landslide thrust and reduced deformation transfer toward the pipeline. The results are site-specific engineering estimates for the investigated rainfall and parameter conditions. Full article

Drought stress is a major environmental factor limiting plant growth and distribution, with severe drought leading to plant mortality. This study investigates the physiological mechanisms underlying drought-induced mortality in one-year-old seedlings of the valuable timber tree species Phoebe bournei (Hemsl.) Yang, aiming to clarify the relative roles of hydraulic failure and carbon starvation. A 51-day controlled pot experiment was conducted to simulate progressive drought using 10 experimental groups (n = 6): a well-watered control and four drought treatment groups harvested at key physiological stages. Stage I (baseline) corresponded to a relative soil water content of approximately 89%. Stage II (photosynthetic cessation) was reached after approximately 15 days of water withholding, at a relative soil water content of approximately 60% and a predawn leaf water potential of approximately −3.4 MPa. Stage III (complete leaf wilting) was reached after approximately 36 days of water withholding. Stage IV (stem browning) occurred at a relative soil water content of approximately 18%, after approximately 45–51 days of water withholding. We systematically measured key physiological parameters, including leaf water potential, gas exchange parameters, the percentage loss of xylem conductivity in stems, and the concentrations of non-structural carbohydrates (including soluble sugars and starch) in different tissues. Results showed that stomatal conductance and net photosynthetic rate approached zero when leaf water potential fell to approximately −3.4 MPa. Stem percentage loss of xylem conductivity increased significantly with advancing drought, exceeding 75% at complete leaf wilting and reaching over 98% at stem browning, reflecting a near-complete loss of xylem hydraulic conductance. Concurrently, non-structural carbohydrate concentrations underwent transient accumulation during early drought, reflecting sink-limited carbon dynamics, followed by progressive depletion. Notably, partial non-structural carbohydrate reserves persisted even at the stem browning stage, suggesting that these reserves may have become physically inaccessible or metabolically unavailable rather than entirely exhausted. The findings point to a tightly coupled, sequential interaction between hydraulic failure and carbon starvation across the drought progression. The findings will provide a scientific basis for evaluating drought tolerance, informing adaptive management practices, and ensuring the sustainable cultivation of P. bournei under future climate scenarios. Full article

Internal temperature distributions in black tea fermentation regulate enzymatic oxidation, heat accumulation and fermentation uniformity, but continuous three-dimensional measurements remain difficult in practical processing. We developed a CFD-prior-constrained physics-informed neural network (PINN + CFD) to reconstruct the three-dimensional thermal state of a 1.35 m × 0.96 m × 0.08 m fermentation bed under sparse sensing. Nine sensors at z = 0.04 m were used for training, and six held-out depth-wise sensors at z = 0.02 m and z = 0.06 m were reserved for depth-wise validation. The model integrated measured temperatures, transient heat-transfer physics, convective boundary conditions and a CFD-derived volumetric soft spatial prior, which guided spatial extrapolation rather than serving as ground-truth temperature data. Although the multilayer perceptron achieved the lowest fitting error at the instrumented z = 0.04 m plane, PINN + CFD showed better depth-wise extrapolation, with RMSEs of 0.128, 0.129 and 0.296 °C across the three stages. However, its advantage was stage- and validation-target-dependent: the baseline PINN was slightly better in part of the dynamic-stage validation, and standalone CFD had the lowest surface infrared error in the constant-temperature stage, indicating that PINN + CFD mainly improved spatial extrapolation rather than uniformly minimizing all error metrics. The inferred apparent process-level heat-source index Q_react(t) varied continuously, and its cumulative trajectory showed a descriptive association with cumulative polyphenol loss. These results indicate that PINN + CFD enables physically consistent thermal-state reconstruction within the tested sparsely instrumented black tea fermentation bed. Full article

Global biodiversity loss undermines ecological integrity and natural capital, yet many biodiversity–finance mechanisms still reward activities rather than verified ecological outcomes, reducing accountability and investor confidence. We introduce Verifiable Nature Units (VNUs), a standardised, outcome-based framework that approximates annual change in ecological integrity at 1 km² resolution. The framework combines an anthropogenic disturbance-based Habitat Intactness (HI) index, derived from remote sensing and spatial datasets, with an Indicator Species (IS) layer estimated through repeated on-site monitoring of selected indicator species across at least three functional guilds. Baselines, tolerance buffers, eligibility criteria, and independent verification requirements translate measured outcomes into investable units. In Majete Wildlife Reserve (711 km²), southern Malawi, HI remained consistently high (0.99) from 2018–2024, with localised declines linked to park infrastructure and extreme weather events. Occupancy analyses for six indicator species across four functional guilds showed high and stable park-level performance from 2021–2025, resulting in all 711 potential VNUs being eligible for issuance in 2024/5. The VNU is not an exhaustive measure of ecological integrity; it is a practical, auditable MRV approach for outcome-based biodiversity finance that can adapt as monitoring systems and ecological metrics mature. Full article

In an era characterized by frequent global supply chain disruptions, manufacturers increasingly explore strategies to safeguard operational continuity, including equity participation in upstream suppliers. This paper investigates partial vertical ownership (PVO), defined as a manufacturer’s partial equity stake in an upstream supplier that supports strategic cooperation and risk information access without full vertical integration. We model a single manufacturer, an unreliable primary supplier with private disruption risk information, and a reliable backup supplier. Relative to a non-ownership (NO) baseline, PVO is modeled as a benchmark governance mechanism that can improve the manufacturer’s information set before backup capacity is reserved. The analytical results show that expected profit is convex in the unit stockout penalty under the specified convex capacity cost structure and deterministic demand assumptions. They also show that the information dividend from PVO is governed by the variance of the disruption probability, while its economic magnitude depends on the scale of stockout losses, backup procurement costs, and the equity return condition. By benchmarking PVO against a clarified option contract strategy, we identify parameter regions in which equity-based information access can outperform contractual hedging. The study reframes PVO as a conditional operational hedging instrument and clarifies the assumptions under which it can strengthen supply chain resilience. Full article

This study addresses the operational challenges of developing hard-to-recover reserves such as heavy-oil rims in weakly consolidated sandstone reservoirs of Western Siberia, which account for a significant share of Russia’s resource base. The core challenge is the inevitable solid production during extraction, leading to abrasive wear, erosion, plugging of downhole pumping equipment, frequent failures, and substantial economic losses. The objective of this work is a comprehensive analysis of the causes of sand production and related equipment failures by integrating published research with field failure data. The research methodology includes an analysis of scientific publications and a statistical review of the causes and frequency of Electrical Submersible Pump (ESP) failures in wells produced by the PK formation. The results show that the primary failure causes are erosive wear (predominantly in medium-rate deviated wells) and plugging by produced solids (predominantly in low-rate horizontal wells), which correlate with sand transport regimes and the particle size distribution (PSD) of produced solids. The failure frequency was found to be comparable across different well types, but the equipment damage mechanisms differed significantly. The discussion confirms the necessity for an integrated approach to modeling the “reservoir–sand control screen–wellbore” system to optimize operating parameters and select effective sand control techniques. Full article

Severe metabolic acidosis is a frequent finding in the intensive care unit (ICU) and a critical marker of clinical severity and organ dysfunction, closely linked to acute kidney injury (AKI) due to shared physiological mechanisms and the loss of the kidney’s ability to maintain acid-base homeostasis. Therefore, it represents the biochemical expression of heterogeneous pathophysiological mechanisms related to acid-base balance. These include tissue hypoperfusion, sepsis, mitochondrial dysfunction, accumulation of unmeasured anions, bicarbonate loss, and reduced renal excretion of the acid load. Its presence is associated with increased mortality, greater vasopressor and mechanical ventilation requirements, prolonged ICU stay, and a higher likelihood of renal replacement therapy (RRT). However, pH correction alone does not guarantee clinical improvement. Therefore, contemporary management prioritizes the etiology, severity of the acidemia, and hemodynamic status. In this context, sodium bicarbonate plays a limited and selective role, particularly in severe acidemia with advanced AKI or hyperkalemia, or as temporary supportive therapy while the underlying cause is corrected or extracorporeal support is arranged. Similarly, RRT should be reserved for refractory cases and should not be initiated based solely on isolated pH thresholds. This review analyzes the definition, epidemiology, clinical implications, pathophysiology, and therapeutic strategies for severe metabolic acidosis in critically ill patients, with emphasis on its interaction with AKI, the rational use of bicarbonate, and the timing of RRT initiation. Full article

We compare neural network architectures for aggregate loss triangle reserving under matched data, training, and evaluation protocols, separating architectural choice from hyperparameter configuration across hundreds of training runs. We compare the GRU Baseline of the DeepTriangle framework against two attention-augmented variants on Workers’ Compensation and Private Passenger Auto data from NAIC Schedule P, and we report two findings. First, attention does not improve reserving accuracy on these short triangles. Both attention variants exhibit a bimodal training instability we call “attention collapse”, in which a sizable fraction of seeds degenerate to a naive mean predictor and the remaining seeds do not reliably outperform the Baseline once the full seed distribution and post hoc survivor filters are considered. Adding or removing the padding mask changes the failure rate only modestly, indicating that the issue is not a masking bug but the limited cross-position information available in 9-lag aggregate triangles. Second, hyperparameter configuration is the dominant driver of accuracy: learning rate receives the largest share of impurity-based importance (about 46%) in a Random Forest decomposition, and tuning the GRU Baseline yields a larger gain over Chain–Ladder than any architectural variant tested. The tuned GRU Baseline remains the recommended starting point for aggregate triangle reserving. Full article

In the context of the China Certified Emission Reduction (CCER) market restart, accounting for forestry carbon sinks faces two challenges: ambiguous theoretical classification and the absence of sound measurement standards. To address the lack of reliable value benchmarks for initial measurement and the distortion of income statements caused by subsequent value fluctuations, this paper establishes an accounting measurement system incorporating the “Environmental Value Equivalence Method” and the “Dynamic Fair Value Adjustment Method” and introduces a dedicated “Environmental Equity Reserve” account. The “Environmental Value Equivalence Method” constructs a weighted average benchmark price using observable market inputs such as CEA and CCER prices, which is then adjusted by an ecological adjustment coefficient to establish an initial valuation anchor. For subsequent measurement, the “Dynamic Fair Value Adjustment Method” is applied, under which changes in fair value are recorded directly in the “Environmental Equity Reserve” account rather than in the income statement, thereby isolating unrealized gains and losses during the holding period from current period profit or loss. Using the afforestation carbon sink project in Honghe Prefecture as a case study and drawing on actual transaction data from the CCER market, the study demonstrates the complete operational process from initial recognition and subsequent adjustments to partial disposal. The findings offer a theoretically grounded and practically feasible solution for the accounting treatment of forestry carbon sinks under China’s CCER mechanism. Full article