Aeroelastic aspects of Axial Compressor Stage with Self-Recirculating Casing Treatment

For successful implementation of casing treatment designs in axial compressors, apart from the stall margin improvement benefits, aeroelasticity also plays a major role. This manuscript addresses the not often discussed aeroelastic aspects of a new discrete type of passive Self-Recirculating Casing Treatment (RCT) designed for a transonic axial compressor stage. Experiments are carefully designed for synchronized measurement of the unsteady fluidic disturbances and vibrations during rotating stall for compressor with baseline solid casing and Self-RCT. The modal characteristics of the axial compressor rotor-disk assembly are studied experimentally and numerically. Experimentally it is observed that the rotating stall cells excite the blades in their fundamental mode in a compressor with baseline solid casing at the stall flow condition. In contrast, there is no excitation of the blades in the compressor with self-recirculating casing treatment at the same solid casing stall flow condition. Also, the self-recirculating casing treatment compared to the solid casing can significantly reduce the overall vibration levels of the blades that are excited at the stall flow condition. The casing treatment is able to alter the flow field near the tip region of the rotor blade, and hence influencing the forcing function of the rotating cantilever blades to have the aeroelastic benefit.

Gelled Acid vs. Self-Diverting Systems for Carbonate Matrix Stimulation: an Experimental and Field Study

The paper considers the choice of the optimal acid treatment technology using chemical flow divertion, for low-temperature heterogeneous and depleted carbonates, based on the analysis of field data, a complex of physico-chemical and core studies. To increase the efficiency of acid treatments of wells that operate the specified reservoir, two technologies of chemical flow divertion (using a gelled acid (GA) and a self-diverting acid (SDA) are considered in the paper. It was revealed that during acid treatments using SDA a longer exposure time of the reagent in the bottom-hole zone (BHZ) of the well is required, as a result of which the planned efficiency for the conditions of the reservoir under consideration is not achieved. By means of core studies, a higher efficiency of using GA under considered conditions was confirmed. The results of physico-chemical and core studies were used to simulate acidizing and adapt treatment designs. Field study of the treatment technology of producing wells with the use of GA was carried out. According to the results of well logging, there is an increase in the working inflow intervals after treatment. The performed field studies confirmed the results of core studies, theoretical studies and physico-chemical surveys.

A Review of Hydraulic Fracturing Simulation

Along with horizontal drilling techniques, multi-stage hydraulic fracturing has improved shale gas production significantly in past decades. In order to understand the mechanism of hydraulic fracturing and improve treatment designs, it is critical to conduct modelling to predict stimulated fractures. In this paper, related physical processes in hydraulic fracturing are firstly discussed and their effects on hydraulic fracturing processes are analysed. Then historical and state of the art numerical models for hydraulic fracturing are reviewed, to highlight the pros and cons of different numerical methods. Next, commercially available software for hydraulic fracturing design are discussed and key features are summarised. Finally, we draw conclusions from the previous discussions in relation to physics, method and applications and provide recommendations for further research.

Design principles of collateral sensitivity-based dosing strategies

Collateral sensitivity (CS)-based antibiotic treatments, where increased resistance to one antibiotic leads to increased sensitivity to a second antibiotic, may have the potential to limit the emergence of antimicrobial resistance. However, it remains unclear how to best design CS-based treatment schedules. To address this problem, we use mathematical modelling to study the effects of pathogen- and drug-specific characteristics for different treatment designs on bacterial population dynamics and resistance evolution. We confirm that simultaneous and one-day cycling treatments could supress resistance in the presence of CS. We show that the efficacy of CS-based cycling therapies depends critically on the order of drug administration. Finally, we find that reciprocal CS is not essential to suppress resistance, a result that significantly broadens treatment options given the ubiquity of one-way CS in pathogens. Overall, our analyses identify key design principles of CS-based treatment strategies and provide guidance to develop treatment schedules to suppress resistance.

High potency of sequential therapy with only beta-lactam antibiotics

Evolutionary adaptation is a major source of antibiotic resistance in bacterial pathogens. Evolution-informed therapy aims to constrain resistance by accounting for bacterial evolvability. Sequential treatments with antibiotics that target different bacterial processes were previously shown to limit adaptation through genetic resistance trade-offs and negative hysteresis. Treatment with homogeneous sets of antibiotics is generally viewed to be disadvantageous, as it should rapidly lead to cross-resistance. We here challenged this assumption by determining the evolutionary response of Pseudomonas aeruginosa to experimental sequential treatments involving both heterogenous and homogeneous antibiotic sets. To our surprise, we found that fast switching between only β-lactam antibiotics resulted in increased extinction of bacterial populations. We demonstrate that extinction is favored by low rates of spontaneous resistance emergence and low levels of spontaneous cross-resistance among the antibiotics in sequence. The uncovered principles may help to guide the optimized use of available antibiotics in highly potent, evolution-informed treatment designs.

High potency of sequential therapy with only beta-lactam antibiotics

Evolutionary adaptation is a major source of antibiotic resistance in bacterial pathogens. Evolution- informed therapy aims to constrain resistance by accounting for bacterial evolvability. Sequential treatments with antibiotics that target different bacterial processes were previously shown to limit adaptation through genetic resistance trade-offs and negative hysteresis. Treatment with homogeneous sets of antibiotics is generally viewed to be disadvantageous, as it should rapidly lead to cross-resistance. We here challenged this assumption by determining the evolutionary response of Pseudomonas aeruginosa to experimental sequential treatments involving both heterogenous and homogeneous antibiotic sets. To our surprise, we found that fast switching between only β- lactam antibiotics resulted in increased extinction of bacterial populations. We demonstrate that extinction is favored by low rates of spontaneous resistance emergence and low levels of spontaneous cross-resistance among the antibiotics in sequence. The uncovered principles may help to guide the optimized use of available antibiotics in highly potent, evolution-informed treatment designs.

The Individualization of the Little Talks Intervention: Implications for Modular Treatment Designs

Modular treatment designs enable interventionists to adapt intervention content to individual clients, a process referred to as individualization. Little is known about individualization processes and its effects on outcomes in early childhood services. This exploratory study investigated individualization processes undertaken by Early Head Start home visitors as they provided Little Talks, a modularized book-sharing intervention for families. It also examined the effect of individualization on parent involvement in early learning activities. Two indicators of individualization were calculated in this study: (a) the proportion of change in the Little Talks’ lessons sequence and (b) the pace of delivery. Findings showed that most home visitors individualized Little Talks, with the most frequent change being the repetition of lessons. Exploratory regression analysis showed an inverse relationship between home visitors’ individualization behavior and parent involvement, highlighting the need to examine the quality of individualization. Implications for advancing the implementation and study of individualization processes in home visiting are discussed.

Effects of Nurse-Led Intervention Programs Based on Goal Attainment Theory: A Systematic Review and Meta-Analysis

This study aimed to evaluate the effects of the goal attainment theory-based nurse-led intervention programs using a systematic review and meta-analysis. Randomized and non-randomized controlled trials, published from January 2001 to December 2020, were examined using four international databases and four domestic databases. The search, selection, and coding were performed independently by two researchers. R version 4.0.3 and Review Manager (version 5.3) were employed for meta-analysis and quality assessment, respectively. Of the 7529 articles retrieved, 18 were selected for analysis. The random overall effect size of the programs was 0.77 (95% CI = 0.61–0.94). Effect size by dependent variables were 2.36 (95% CI = 0.91–3.82), 1.25 (95% CI = 0.66–1.83), 0.83 (95% CI = 0.55–1.10), 0.64 (95% CI = 0.39–0.89), and 0.58 (95% CI = 0.30–0.85) for interpersonal, cognitive, health behavior, psychological, and indicators of physical health, respectively. Effect size by independent variables were 1.25 (95% CI = 0.86–1.64), 0.76 (95% CI = 0.48–1.03), 0.72 (95% CI = 0.37–1.06), 0.35 (95% CI = 0.21–0.49), and 1.35 (95% CI = −0.15–2.85) for prevention, health promotion, counseling and education, goal-setting and health contract, and parent participation programs, respectively. The effect size by control variables was 1.72 (95% CI = 0.88–2.56) at age ≤17, 0.85 (95% CI = 0.54–1.15) at time (min) 61–90, 1.04 (95% CI = 0.76–1.32) at sessions seven to eight, and 0.93 (95% CI = 0.66–1.19) at duration (weeks) five to eight. Thus, these programs were effective in improving various health aspects. Additionally, they can be recommended in various settings. Because efficacy is also influenced by control variables, considering treatment designs based on intervention characteristics and methodological approaches is warranted.

A Multi-Disciplinary Approach for Well Spacing and Treatment Design Optimization in the Midland Basin Using Lateral Pore Pressure Estimation and Depletion Modeling

With a recent trend in increased infill well development in the Midland basin and other unconventional plays, it has been shown that depletion has a significant impact on hydraulic fracture propagation. This is largely because production drawdown causes in-situ stress changes, resulting in asymmetric fracture growth toward the depleted regions. In turn, this can have a negative impact on production capacity. For the initial part of this study, an infill child well was drilled and completed adjacent to a parent well that had been producing for two years. Due to drilling difficulties, the child well was steered to a new target zone located 125 feet above the original target. However, relative to the original target, treatment data from the new zone indicated abnormal treatment responses leading to a study to evaluate the source of these variations and subsequent mitigation. The initial study was conducted using a pore pressure estimation derived from drill bit geomechanics data to investigate depletion effects on the infill child well. The pore pressure results were compared to the child well treatment responses and bottom hole pressure measurements in the parent well. Following the initial study, additional hydraulic fracture modeling studies were conducted on a separate pad to investigate depletion around the infill wells, determine optimal well spacing for future wells given the level of depletion, and optimize treatment designs for future wells in similar depletion scenarios. A depletion model workflow was implemented based on integrating hydraulic fracture modeling and reservoir analytics for future infill pad development. The geomechanical properties were calibrated by DFIT results and pressure matching of the parent well treatments for the in-situ virgin conditions. Parent well fracture geometries were used in an RTA for an analytical approach of estimating drainage area of the parent wells. These were then applied to a depletion profile in the hydraulic fracture model for well spacing analysis and treatment design sensitivities. Results of the initial study indicated that stages in the new, higher interval had higher breakdown pressures than the lower interval. Additionally, the child well drilled in the lower interval had normal breakdown pressures in line with the parent well treatments. This suggests that treatment differences in the wells were ultimately due to depletion of the offset parent well. Based on the modeling efforts, optimal infill well spacing was determined based on the on-production time of the parent wells. The optimal treatment designs were also determined under the same conditions to minimize offset frac hits and unnecessary completion costs. This case study presents the use of a multi-disciplinary approach for well spacing and treatment optimization. The integration of a novel method of estimating pore pressure and depletion modeling workflows were used in an inventive way to understand depletion effects on future development.