Search Results (93)

This study addresses the challenge of non-uniform fracture propagation in multi-cluster staged fracturing of horizontal wells by proposing a three-dimensional dynamic simulation method for temporary plugging fracturing, grounded in a fully coupled fluid–solid damage theory framework. A Tubing-CZM (cohesive zone model) coupling model was developed to enable real-time interaction computation of flow distribution and fracture propagation. Focusing on the Xinjiang X Block reservoir, this research systematically investigates the influence mechanisms of reservoir properties, engineering parameters (fracture spacing, number of perforation clusters, perforation friction), and temporary plugging parameters on fracture propagation morphology and fluid allocation. Our key findings include the following. (1) Increasing fracture spacing from 10 m to 20 m enhances intermediate fracture length by 38.2% and improves fracture width uniformity by 21.5%; (2) temporary plugging reduces the fluid intake heterogeneity coefficient by 76% and increases stimulated reservoir volume (SRV) by 32%; (3) high perforation friction (7.5 MPa) significantly optimizes fracture uniformity compared to low-friction (2.5 MPa) scenarios, balancing flow allocation ratios between edge and central fractures. The proposed dynamic flow diversion control criteria and quantified temporary plugging design standards provide critical theoretical foundations and operational guidelines for optimizing unconventional reservoir fracturing. Full article

The growing application of carbon fiber-reinforced polymers (CFRPs) in construction opens new possibilities for replacing traditional materials such as steel, particularly in strengthening and retrofitting concrete structures. CFRP materials offer notable advantages, including high tensile strength, low self-weight, corrosion resistance, and the ability to be tailored to complex geometries. This paper provides a comprehensive review of current technologies used to strengthen concrete columns, with a particular focus on the application of fiber-reinforced polymer (FRP) tubes in composite column systems. The manufacturing processes of FRP composites are discussed, emphasizing the influence of resin types and fabrication methods on the mechanical properties and durability of composite elements. This review also analyzes how factors such as fiber type, orientation, thickness, and application method affect the load-bearing capacity of both newly constructed and retrofitted damaged concrete elements. Furthermore, the paper identifies research gaps concerning the use of perforated CFRP tubes as internal reinforcement components. Considering the increasing interest in innovative column strengthening methods, this paper highlights future research directions, particularly the application of perforated CFRP tubes combined with external composite strengthening and self-compacting concrete (SCC). Full article

Proper determination of the bottomhole pressure in a gas lift well is essential to enhance production, tackle operating concerns, and use the least amount of gas. Mechanistic models, empirical correlation, and hybrid models are usually limited by the requirements for calibration, large amounts of inputs, or limited scope of work. Through this study, sixteen well-tested machine learning (ML) models, such as genetic programming-based symbolic regression and neural networks, are developed and studied to accurately predict flowing BHP at the perforation depth, using a dataset from 304 gas lift wells. The dataset covers a variety of parameters related to reservoirs, completions, and operations. After careful preprocessing and analysis of features, the models were prepared and tested with cross-validation, random sampling, and blind testing. Among all approaches, using the L-BFGS optimizer on the neural network gave the best predictions, with an R² of 0.97, low errors, and better accuracy than other ML methods. Upon using SHAP analysis, it was found that the injection point depth, tubing depth, and fluid flow rate are the main determining factors. Further using the model on 30 unseen additional wells confirmed its reliability and real-world utility. This study reveals that ML prediction for BHP is an effective alternative for traditional models and pressure gauges, as it is simpler, quicker, more accurate, and more economical. Full article

Passive, compound, and active augmented heat transfer (AHT) methods in a countercurrent flow concentric tube heat exchanger (CCTHE) were explored and examined in this work. The finite volume method using ANSYS Fluent 2021 R2 was applied to evaluate the fluid flow and heat transfer characteristics of a CCTHE in each AHT study. The influence of the circular perforated insert at varied quantities (N) was analyzed in a passive AHT study. A comparable heat transfer improvement of 41.8% was recorded at an insert quantity of N = 7; however, a notable decreasing trend in the thermal performance factor (α) indicated that pressure drop increases as the number of inserts increases. In the active AHT study, the inner pipe rotation at 300 rad/s resulted in a heat transfer rate enhancement of 428%. The compound AHT method employed rotating perforated inserts at various rotational speeds, which resulted in a heat transfer rate increase of 47.5% at 300 rad/s and N = 7. This work demonstrated how each type of flow disturbance affected the heat transfer rate inside a CCTHE and investigated the effectiveness of each method through the evaluation of α. Full article

Intra-abdominal and gastrointestinal mucormycosis are less frequent than rhino-orbito-cerebral and pulmonary mucormycosis, but highly lethal. Their diagnosis remains challenging due to the non-specific clinical presentation. We collected English-language cases of intra-abdominal and gastrointestinal mucormycosis in non-haematological and non-neonatal patients published up to October 2024. This review analysed the epidemiological, clinical, and therapeutic charts of 290 cases. A proportion of 53.4% were reported from India and the USA. The main predisposing conditions were diabetes, solid organ transplant, ICU, and corticosteroid treatment. The most common site was the stomach (53.8%). Gastrointestinal perforation, skin breakdown, and abdominal wall infection were sources of intra-abdominal localisation. The most common symptoms were abdominal pain, vomiting, and gastrointestinal bleeding. The diagnosis relied on histology (93.8%), mycology with microscopy and culture (38.8%), and molecular methods (9.9%). Mortality (52.9%) was lower when treatment was intravenous amphotericin B, combined or not with surgery. Prompt treatment, essential for a favourable outcome, relies on early suspicion and diagnosis. Gastrointestinal and intra-abdominal mucormycosis should also be suspected in patients admitted in ICU with ventilation/nasogastric tube and corticosteroids and those with abdominal trauma or surgery, presenting abdominal distension, pain, and GI bleeding. Mycological diagnosis including direct examination, culture and Mucorales qPCR on tissue should assist with rapid diagnosis and thus treatment. Full article

In order to improve the acoustic performance of honeycomb sandwich structures, a Helmholtz-type honeycomb sandwich acoustic metamaterial (HHSAM) was proposed. The theoretical and finite element models were established by calculating the acoustic impedance of multiple parallel Helmholtz resonators (HR). By comparing the sound absorption of the single and multiple HR, it was found that the simulation results were basically consistent with the theoretical calculations. The sound absorption and insulation performance of the honeycomb panels, the honeycomb perforated panels, and the HHSAM structure were compared through impedance tube experiments. The results showed that, over a wide frequency range, the acoustic performance of the HHSAM structure was superior to that of the other two structures. Under scattered sound field conditions, the reverberation room results showed that the sound absorption of the HHSAM structure was better than that of the honeycomb panel in the frequency range of 100–5000 Hz. The noise reduction coefficient (NRC) of the honeycomb panel was 0.1, indicating almost no sound absorption effect in engineering. The NRC of the HHSAM structure could reach 0.35. In terms of sound insulation, the HHSAM structure was more prominent in the 400–4000 Hz range than the honeycomb panel. In the frequency range of 500–1600 Hz, the transmission loss of the HHSAM was 5 dB higher than that of the honeycomb panel. Full article

Over 250,000 gastrostomy tubes (G-tubes) are placed annually in the United States. Percutaneous endoscopic gastrostomy (PEG) is the most widely used clinical method for placing G-tubes within the stomach. However, endoscope detectability is limited due to the scattering of light by tissues. Poor organ visibility and low sensitivity of the palpation techniques cause blind needle insertions, which cause colon/liver perforations, abdominal bleeding, and gastric resections. Additionally, imaging artifacts and the poor distinguishability between water-filled tissues make ultrasound (US) imaging-based techniques incompatible with G-tube placement. The risk of ionizing radiation exposure and the confinement of fluoroscopy to radiology suites limits its bedside utility in patients. Considering these limitations, we propose to design a safe, point-of-care integrated US and photoacoustic (PA) imaging system for accurate G-tube placement procedures, for a broad spectrum of patients, and to characterize the system’s effectiveness. Our proposed technology utilizes a clinically safe contrast agent and a dual-wavelength approach for precise procedures. Our ex vivo tissue studies indicated that PA imaging accurately differentiates the different organs at specific wavelengths. Our characterization studies revealed that PA imaging could detect lower concentrations of Indocyanine Green (ICG) dye coating the colon wall, minimizing the risk of ICG dye-related toxicity and providing safer G-tube placements. Full article

Background: Acute colonic pseudo-obstruction (ACP) is a life-threatening, rare condition of non-mechanical colon dilatation that can result in bowel ischaemia and perforation. The aetiology is relatively unknown but includes older age coupled with high comorbidity, decreased parasympathetic activity, certain medications, chemoradiotherapy and recent surgery. There are limited research data on ACP following reversal of ileostomy after ultra-low anterior resections (ULAR), thus this systematic review included cases from various types of bowel surgeries. Methods: A comprehensive literature search of relevant articles was conducted using the EMBASE, Medline, PubMed, Cochrane, and Scopus databases. Two cases of ACP following ileostomy reversal after ULAR for rectal cancer were also reported from the authors’ rural institution. This systematic review was conducted according to PRISMA 2020 guidelines. Results: A total of 522 studies were screened of which five case reports were included. Two case series (six patients) and the two patients from the authors’ rural institution developed ACP following reversal of ileostomy post-ULAR with potential causes being the > 6 months’ time from initial surgery to reversal causing prolonged colonic mucosal inflammation and reduced wall contractile strength. Anastomotic leak and chemoradiotherapy were other considerations. One of the rural patients developed right colon ischaemia and perforation needing urgent laparotomy, right hemicolectomy and formation of end ileostomy and mucous fistula. Conservative treatment included aperients, enemas, flatus tube, bedside or endoscopic decompression, and neostigmine. Conclusions: Early recognition is vital to treat ACP with medical therapy and decompression to prevent bowel ischaemia and perforation. Further research is needed to better characterise the aetiology, incidence and management strategies for this rare condition. Full article

A novel L-shaped concrete-filled steel tube (CFST) column is proposed in this study. A finite element model of the column is developed using ABAQUS software to analyze its load transfer mechanism and axial compressive behavior. The effects of factors such as the steel strength, steel tube thickness, support plate configuration, and perforation of the support plates on the compressive performance of the column are investigated. The simulation results reveal that the column exhibits robust axial compressive performance. Increasing the steel strength and incorporating support plates (SP) effectively enhance the column’s compressive bearing capacity and positively influence the bearing capacity coefficient (δ). However, increasing the steel tube thickness results in a reduction in δ, indicating that the rate of increase in the bearing capacity diminishes with increasing thickness. The failure mode is primarily characterized by local buckling in the midsection of the steel tube’s concave corner. Measures such as increasing the steel strength and tube thickness and the use of support plates help to mitigate buckling at the concave corner, improve concrete confinement, and enhance the overall compressive performance of the column. Full article

The primary aim of this work was to share the results from a Research Project supported by the Italian National Research Council, which led to the development of a versatile jacketed tower bioreactor. Designed to optimize oxygen transfer efficiency and process control, the reactor incorporated a reciprocating air compressor, centrifugal pumps, a draft tube with or without perforated plates, and a series of gas–liquid ejectors. Its flexible design enabled operation in both airlift and ejector-loop modes, making it suitable for a wide range of aerobic fermentation processes. By sharing the detailed engineering design, operational procedures of this pilot-scale bioreactor, as well as its performance data when cultivating yeasts on whey and potato wastewater, a detailed blueprint was given to researchers seeking to advance bioreactor technology, particularly in the context of emerging fields like cultured meat production, pharmaceutical manufacturing, and environmental bioremediation. Full article

Acoustic metamaterials offer new opportunities for controlling sound waves through engineered material configurations at the sub-wavelength scale. In this research, we present the optimization of a resonance-controlled acoustic metamaterial based on a sandwich structure composed of perforated plexiglass disks, honeycomb structures, and added metal masses. The innovative approach consists of integrating perforated plexiglass disks interspersed with honeycomb structures, which act as multiple and complex Helmholtz resonators, and adding metal masses to introduce resonances at specific frequencies. The metamaterial’s acoustic properties were experimentally characterized using an impedance tube (Kundt tube), allowing the measurement of the Sound Absorption Coefficient (SAC) over an expansive frequency selection. The results demonstrate a substantial enhancement in sound absorption at the target frequencies, demonstrating the effectiveness of the introduced resonances. Numerical simulations using an Artificial Neural Network (ANN) model in MATLAB environment were used to analyze the distribution of resonances and optimize the structural configuration. To effectively evaluate the acoustic properties of the metamaterial, various configurations were analyzed using perforated plexiglass disks combined with different layers of honeycombs arranged in a sandwich structure with a thickness ranging from 41 to 45 mm. A comparison of these configurations revealed a notable increase in the Sound Absorption Coefficient (SAC) when employing three layers of perforated plexiglass disks and adding masses to the first disk (about 14%). This study highlights the potential of resonance-controlled metamaterials for advanced applications in noise control and acoustic engineering. Full article

Background/Objectives: Perforations represent rare but serious complications in ERCP. Although several therapeutic algorithms have been proposed to properly address these potentially life-threatening events, there is still no clear consensus on their management. We conducted a single-center retrospective study in order to assess the incidence of ERCP-related perforations and their management, as well as clinical outcomes. Methods: The hospital’s electronic database was searched in order to identify all the patients who developed ERCP-related perforations in the period 1 October 2018–30 June 2023. Perforations were classified according to the Stapfer classification. Conservative management included frequent abdominal examinations, the monitoring of vital signs, white blood cell count, complete bowel rest, nasogastric tube placement, and the administration of intravenous fluids and antibiotics. Endoscopic management included biliary stent placement and/or closing observed defects with clips. Results: We recorded eight (1.29%) cases of ERCP-related perforations out of the 619 procedures conducted. We observed six (75%) Stapfer type II and two (25%) type IV perforations. In all but one patient (87.5%), the indication for ERCP was bile duct stones. Seven patients (87.5%) were subjected to sphincterotomy (87.5%) and three (37.5%) to “pre-cuts”. All but one patient was treated conservatively (87.5%), with two of them—in which type II perforations were recognized intraprocedurally—also receiving endoscopic treatment with stent placement. On the day of ERCP, one patient with a type II perforation was operated on; suturing of the duodenum followed by duodenal exclusion was applied. Management was successful in all the patients, with a mean hospitalization time of 16.6 ± 4.78 days. Conclusions: Conservative and endoscopic management appear to be associated with good outcomes in Stapfer type II perforations. Nevertheless, an individual multidisciplinary approach involving endoscopists and a hepatobiliary surgeon is essential in order to properly guide the treatment. Full article

In recent years, the optimization of diesel engine exhaust mufflers has predominantly targeted acoustic performance, while the impact on engine power performance has often been overlooked. Therefore, this paper proposes a parallel perforated tube expansion muffler and conducts a numerical analysis of its acoustic and aerodynamic performance using the finite element method. Then, a Kriging model is established based on the Design of Experiments to reveal the impact of different parameter couplings on muffler performance. With transmission loss (TL) and pressure loss (PL) as the optimization objectives, a multi-objective optimization study is carried out using the competitive multi-objective particle swarm optimization (CMOPSO). The optimization results indicate that this method can simplify the optimization model and improve optimization efficiency. After CMOPSO calculation, the average TL of the muffler increased from 27.3 dB to 31.6 dB, and the PL decreased from 1087 Pa to 953 Pa, which reduced the exhaust noise and improved the fuel economy of the engine, thus enhancing the overall performance of the muffler. This work provides a reference and guidance for the optimal design of mufflers for small agricultural diesel engines. Full article

This paper investigates the application of Schlieren flow visualization for detecting leaks in pipelines carrying high-temperature fluids. Two experimental setups were constructed: one with a 25 mm PTFE tube featuring a 2 mm diameter perforation, and another with a 100 mm diameter pipe insulated with an aluminum jacket and featuring a 12 mm leak gap. A single-mirror-off-axis Schlieren system, employing a 150 mm diameter parabolic mirror, was used to visualize the leaks. The temperature of the leaking air varied between 20 and 100 °C, while the ambient temperature was maintained at 14 °C. To quantify the leaks, the coefficient of variation for pixel intensity within the leak region was calculated. Results showed that for the PTFE tube, leaks became detectable when the temperature difference exceeded 34 °C, with the coefficient of variation surpassing 0.1. However, in the insulated pipe, detecting clear leak patterns was challenging. This research demonstrates the potential of Schlieren visualization as a valuable tool in enhancing pipeline leak detection. Full article

With advancements in the exploration and development of deep and ultra-deep oil and gas resources, the number of ultra-deep wells continues to rise globally. This trend places higher demands on testing technology. The combined perforating and testing technique, an established method for deep and ultra-deep wells, faces challenges. Frequent test operation failures due to perforation detonation failure increase down-hole complexity, restricting the timeliness of testing operations. Current methods use mechanical calibration software to calculate the minimum safety factor of the tubing string for safety assessments. However, without a thorough understanding of perforation detonation failure theory, existing mechanical analysis software remains unreliable for assessing well safety during operations. Simply using the safety factor method lacks reliability and cannot explain the causes of perforation detonation failure. This paper examines an ultra-deep well, referred to as TW1, to analyze perforation detonation failure mechanisms. Through metal microstructure examinations, chemical composition analysis, electron microscope scanning, and numerical simulation, the study yields the following insights: (1) The packer mandrel of Well TW1 fractured due to overstress from the detonation waves. (2) Detonation wave propagation patterns along the tubing string during perforation become apparent. (3) Simulation methods reconstruct the perforation detonation process, calculating effective stress at different tubing string positions over time. (4) It introduces an innovative approach for assessing perforation detonation failure mechanisms through a combination of laboratory testing and simulation modeling. Full article