Leak Test Research Articles

Interfacial property determination from dynamic pendant-drop characterizations.

The properties of the interface between materials have practical implications in various fields, encompassing capillary action, foam and emulsion stability, adhesion properties of materials and mass and heat transfer processes. Studying the dynamics of interfaces is also fundamental for understanding intermolecular interactions, change of molecular conformations and molecular aggregations. Pendant-drop tensiometry and its extension, the oscillating drop method, are simple, versatile methods used to measure surface tension, interfacial tension and interfacial rheological properties. These methods can, however, generate unreliable results because of inadequate material preparation, an incorrect calibration method, inappropriate selection of data for analysis, neglect of optical influences or operating the system outside the linear viscoelastic regime. In addition, many studies fail to report accurate uncertainties. This protocol addresses all these critical points and provides detailed descriptions of some operation tips relating to purifying methods for different kinds of material, the time frame for analyzing measurement data, the correction method for optical effects, implementation of the oscillating method with a common programmable pump and remedies for some common problems encountered during the measurement. Examples of interfacial tension measurements for two- and three-phase systems, as well as interfacial dilational modulus measurements for N2 and surfactant solutions, are provided to illustrate procedural details and results. A single measurement takes minutes to hours to complete, while the entire protocol, including the leak test, cleaning, repeated measurements and data analysis, may take several days.

Feasibility of lung lobectomy through a transdiaphragmatic approach in dogs.

Different pulmonary pathologies may require a partial or total lung lobectomy as treatment. This study compared two techniques for performing a caudal pulmonary lobectomy: a traditional lateral thoracotomy (LT) and a novel transdiaphragmatic (TD) approach. TD and LT approaches were performed on each of 18 canine cadavers. The operator and order of intervention were randomised at the beginning of the study. To compare both techniques, surgical time, percentage of area of lobe removed, incision length and iatrogenic damage were recorded. The mean length of surgery for the TD approach (1155±232.8 seconds) was non-inferior to the LT approach (1126.8±180.6 seconds) (p=0.6131). The mean percentage of the area of caudal lobe that was successfully removed during the TD approach was 25.83±8.95% (range 10.55‒40.72%) of the lobe surface, while 100% of the caudal lobe was removed during the LT approach. There was no statistical difference in iatrogenic damage between the procedures. This is a non-inferiority ex vivo study carried out by three different surgeons, and no leak test was performed after lobectomies. Partial caudal lung lobectomy can be performed in dogs by the TD approach without greater iatrogenic damage or longer surgical duration than the traditional LT approach.

Routine conventional leak test is not required for robotic major pulmonary resections.

We retrospectively evaluated whether or not conventional air leak testing is necessary in robotic major pulmonary resections. After excluding patients who received 2 or more days of postoperative drainage for chylothorax or excessive pleural effusion, 578 patients who underwent major pulmonary resection using minimally invasive approaches between February 2019 and November 2023 at our institution were included in this study. All patients were divided into two groups including thoracoscopic (n = 471) and robotic (n = 107) approaches. Conventional air leak testing was performed in all patients in the thoracoscopic approach but not in the robotic approach. After propensity score matching of patient backgrounds between the two groups, perioperative outcomes were compared (n = 100 each). The primary endpoint was the rate of drain removal on postoperative day (POD) 2 or later. In addition, factors associated with drain removal on POD 2 or later in the robotic group were identified. The rate of drain removal at POD 2 or later was not significantly different between the two groups (p = 0.011). Multivariable analysis to identify factors associated with drain removal at POD2 or later in the robotic approach showed that sealant application (p = 0.002) and lobectomy (vs. segmentectomy, p = 0.034) were significantly associated. In conclusion, even in the absence of air leak testing, a robotic approach for major lung resections can result in a drain removal rate on the day of surgery or POD1 that is comparable to a conventional thoracoscopic approach. However, it may be useful in selected patients requiring sealant placement or undergoing lobectomy.

EP118 - Chronic Vesicouterine Fistula (Youssef's syndrome) Complete Opening of Anterior Uterine Wall in the Urinary Bladder: A- very rare case

Abstract Background Vesicouterine fistula is an uncommon urogenital condition typically following Caesarean sections (C/S). Youssef syndrome, characterized by haematuria, amenorrhea, and urinary incontinence, poses a diagnostic challenge and demands comprehensive assessment. Case report We present a case of a 40-year-old woman with persistent urine incontinence and haematuria for three years post her fourth C/S. Clinical evaluation revealed periodic lower abdominal pain, haematuria, amenorrhea, and urine incontinence. sonography was normally reported, while cystoscopy revealed a complete 5x2 cm opening between the anterior uterine wall and the posterior bladder wall, confirming Youssef syndrome. After a course of antibiotic therapy, surgical intervention was planned. Transabdominal total hysterectomy, partial cystectomy, and repair were performed following meticulous anatomical delineation using cystoscopy. The procedure involved dissecting the vesicouterine attachment, performing partial cystectomy, and eventually total hysterectomy. Closure of the urinary bladder defect with absorbable sutures and a negative leak test concluded the surgery. The patient showed no postoperative complications, with follow-ups at 6 and 12 months indicating complete recovery without complaints.

An audit of perioperative speech pathology intervention on improving enhanced recovery after surgery in oesophagectomy patients

Purpose To evaluate the impact of a speech-language pathology (SLP) pathway on recovery following oesophagectomy. Method An audit was conducted at a single metropolitan public hospital in Sydney, Australia. Patients between 2014–2021 undergoing a three-stage oesophagectomy (n = 41) were included in the study. The sample was divided into two groups, those who received usual care (2014–2019) and those who received perioperative SLP assessment and intervention (2020–2021), with data collected across swallowing and health outcomes. Patient demographics and outcomes between the two groups were compared. Result Patients who received perioperative SLP intervention commenced oral intake faster postoperatively (SLP intervention group Mdn = 6.50 days, IQR = 6.00–7.00; usual care group Mdn = 9.00 days, IQR = 7.00–13.25; p = 0.001). There was no statistically significant difference between groups in rates of aspiration on the postoperative leak test (p = 0.32). No statistically significant differences were found between the two groups in length of hospital stay or number of swallowing-related medical images completed during their admission. Conclusion Perioperative SLP intervention has a positive impact on commencing oral intake following a three-stage oesophagectomy, however, it does not have a significant impact on rates of aspiration postoperatively. This pathway may contribute to enhanced recovery after oesophagectomy.

Volumetric efficiency degradation prediction of axial piston pump based on friction and wear test

The axial piston pump (APP) is being developed towards higher pressure and higher rotational speeds to enhance operational power density. The piston-cylinder friction pair is a critical component of the APP. Due to its lack of self-compensation capability, the leakage of the piston-cylinder friction pair escalates rapidly under increasingly severe wear conditions. An innovative method for predicting the performance degradation and lifespan of APPs based on friction and wear tests has been proposed. This method can effectively predict the performance degradation trends of APPs under different operating conditions. The actual contact force on the piston pair (PP) during operation is determined through dynamic analysis. Friction and wear tests were conducted on 38CrMoAl piston and ZCuPb15Sn8 cylinder materials under various conditions using a testing apparatus. Utilizing friction and wear theory, the volumetric efficiency of APP under various operating conditions was derived as a function of operational time. The reliability of the theoretical analysis was validated through leakage tests on the APP. The results indicate that volumetric efficiency decreases exponentially with increasing working pressure at rated speed. This research provides theoretical guidance and an experimental foundation for the failure prediction of volumetric efficiency degradation in APP.

Six-year analysis of 30-day post-operative leaks for primary sleeve gastrectomy: a MBSAQIP database study.

Sleeve gastrectomy is the most performed bariatric surgery. Post-operative gastric sleeve leaks, although rare, are dreaded complications. This study aims to perform an updated investigation of the factors associated with sleeve leaks. This retrospective cohort study analyzed 692,554 cases from the MBSAQIP database (2016-2021) with CPT code 43,775 for primary sleeve gastrectomy. We excluded emergency operations, conversions/revisions, endoscopic interventions, patient with prior foregut surgery, and open operations. Multivariate logistic regression analysis (STATA version 15) was performed to identify factors associated with sleeve gastrectomy leaks. Out of 692,554 patients, 600,910 (86.77%) patients underwent laparoscopic sleeve gastrectomy, and 91,644 (13.23%) patients underwent robotic sleeve gastrectomy. 1179 (0.17%) developed leaks within 30days; 177(0.19%) were in the robotic group and 1002 (0.17%) in the laparoscopic group with no significant difference in leak rates between two groups on multivariate analysis. Black patients had lower odds of having leaks as compared to white patients (Odds Ratio (OR): 0.68 (0.56-0.82); p < 0.01). Hispanic patients had lower odds of having leak as compared to non-Hispanics. Factors associated with higher leak odds (p < 0.05) included hypertension, GERD, smoking, immunosuppression, increased operating time, and albumin < 3.5g/dl. Higher odds of leaks were observed in years 2016-2019 vs 2020-2021 (OR: 1.44 (1.25-1.65), p < 0.01). Higher odds of leak in operations with general surgeons compared to bariatric surgeons was found (OR: 1.46 (1.04-2.02), p = 0.02); observed only on robotic group on subgroup analysis (OR: 2.2 (1.2-4.2), p = 0.02). Staple line reinforcement, oversewing, and performance of leak test showed no differences in leak rate. Bougie size and distance from pylorus were not associated with changes in leak rate. This study provides updated insights into the factors associated with sleeve leaks, reinforcing information gained from prior studies. A higher association of leak among general surgeons could represent a learning curve for new robotic general surgeons. The overall decreasing trend for gastric sleeve leak is encouraging and may be a sign of improved techniques.

A composite testing method of homologous magnetic flux leakage and motion-induced eddy current for inner and outer defects

Magnetic flux leakage (MFL) testing, widely utilized for pipeline integrity assessments due to its efficiency and accuracy, is often challenged by motion-induced eddy currents (MIEC) that can distort MFL signals. Contrary to traditional perspectives that consider MIEC as detrimental, this paper introduces a novel MFL-MIEC composite testing method. This method leverages MIEC as a complementary technique while sharing the same excitation source. By exploring the generation and influence of MIEC on MFL signals, we simulate optimal probe positions and analyze the effects of defect position, angle, and detection speed on signal quality. Adjustments in the detection coils orientation are shown to enhance signal strength, demonstrating the methods effectiveness in identifying pipeline defects through practical experiments. This approach offers significant potential for widespread application in pipeline assessments.

A novel instrumentation approach for achieving in-situ temperature sensing of a Li-ion cylindrical cell under immersion cooling

Battery thermal management systems are critical for high-performance electric vehicles, where the ability to remove heat and homogenize temperature distributions in single cells and packs are key considerations. Immersion cooling, which immerses the battery in a dielectric fluid, can improve cooling efficiency compared to air cooling. However, stringent instrumentation standards make in-situ monitoring under immersion cooling a difficult challenge. This study proposes a novel cell instrumentation method based on the integrated combination of three O-rings, which for the first time achieves in-situ temperature sensing of batteries under oil-immersed cooling conditions. Reliability of the sealing system and instrumentation methodology is ensured by leakage tests and oil corrosion assessment. Data such as cell impedance and discharge capacity also support the success and reliability of the instrumentation process without affecting the battery performance. Compared with natural air cooling, immersion cooling can reduce the temperature rise during battery operation by >10 °C under high C-rate discharge conditions. However, this is accompanied by an increase in radial temperature gradient. The temperature gradient of the cell with oil immersed reaches a maximum of >7 °C, while the temperature gradient under natural cooling under the same test conditions is only 3 to 4 °C. This leads to intensified temperature inhomogeneity of the cell, which may accelerate the local ageing and degradation. Our instrumentation approach contributes to a deeper understanding of the thermal behaviour of batteries under direct immersion cooling, aiding the development of more advanced cooling strategies and associated battery thermal management models.

Feasibility of triple assessment of the anastomosis using an anastomotic checklist.

Colorectal cancer is the third most common cancer and the second highest cause of cancer mortality in Australia. Despite advances in colorectal surgery, anastomotic leak still occurs in low-risk patients and is a substantial cause of morbidity and mortality. Many operative strategies are used to assess anastomotic integrity such as an air leak test or intraoperative flexible sigmoidoscopy, however an objective anastomotic checklist is yet to be developed and studied. This study aims to develop a photodocumentary anastomotic specific checklist and determine its feasibility for implementation. Patients undergoing left sided colorectal resections with primary anastomosis without a de-functioning ileostomy were prospectively included between May 2021 and December 2022. A photographic checklist assessing anastomotic perfusion, integrity via either air test or endoscopic image, evidence of complete operative doughnut specimens and the assessment of tension was implemented. The feasibility of an anastomotic checklist was externally validated by four independent colorectal surgeons from Australia, New Zealand and United States of America. The anastomotic checklist was completed in 44 patients. Mean age was 62 years, with 43% male and mean BMI 28. Operations included high anterior resection (45%), low anterior resection (18%), ultra-low anterior resection (20%), reversal of Hartmann's (11%). Median length of stay was 4 days. Complications post operatively were documented in six patients with anastomotic leak in 2% and wound infection in 6.8%. Intraclass correlation coefficients were poor amongst all reviewers with air leak and tension having no inter-reviewer correlation. The introduction of an anastomotic checklist was a feasible tool to systematically assess and document anastomotic integrity. Unfortunately, with the small sample size there was significant discrepancy in inter-observer variability, and this led to poor correlation regarding which patients were typically high risk requiring a temporary ileostomy. Larger studies on the implementation of an anastomotic checklist will be needed to evaluate if it is an inherently feasible approach and if there is an effect on anastomotic leak.

Parametric design methodology for yoke-magnetization in magnetic flux leakage detection systems

Magnetic flux leakage (MFL) testing is a widely employed non-destructive testing (NDT) method, particularly for ferromagnetic materials. This paper proposes a systematic design procedure for the yoke-magnetization component in MFL systems utilizing permanent magnets. The dimensions of the yoke-magnetization are parameterized, and the design methodology is formulated in the form of analytical equations based on fundamental engineering principles and optimization techniques. The proposed design procedure outlines all the required parameters and metrics to establish a yoke-magnetization configuration tailored for a specified application, thereby facilitating scalability. The theoretical framework identifies the optimal operating point that maximizes leakage flux while minimizing the magnetic field amplitude. A genetic algorithm is employed to minimize the dimensions of the permanent magnets while maintaining a sufficient magnetic field strength for specimen magnetization. An experimental setup is constructed to validate the accuracy of the proposed design procedure. The experimental results exhibit consistency with finite element method (FEM) simulations conducted using a case study. Specifically, the findings reveal that the thickness of the magnetic bridge significantly impacts the leakage fluxes at defect sites within the specimen. When the thickness of the magnetic bridge is 10 mm, slightly smaller than the optimal thickness of approximately 11 mm, the leakage flux at the defect site leaks out towards the surrounding air insignificantly. In contrast, a thickness of 15 mm is observed to strongly improve the leakage flux at the defect site.

Fabrication of Porous Collagen Scaffolds Containing Embedded Channels with Collagen Membrane Linings.

Tissues and organs contain an extracellular matrix (ECM). In the case of blood vessels, endothelium cells are anchored to a specialized basement membrane (BM) embedded inside the interstitial matrix (IM). We introduce a multi-structural collagen-based scaffold with embedded microchannels that mimics in vivo structures within vessels. Our scaffold consists of two parts, each containing two collagen layers, i.e., a 3D porous collagen layer analogous to IM lined with a thin 2D collagen film resembling the BM. Enclosed microchannels were fabricated using contact microprinting. Microchannel test structures with different sizes ranging from 300 to 800 µm were examined for their fabrication reproducibility. The heights and perimeters of the fabricated microchannels were ~20% less than their corresponding values in the replication PDMS mold; however, microchannel widths were significantly closer to their replica dimensions. The stiffness, permeability, and pore size properties of the 2D and 3D collagen layers were measured. The permeability of the 2D collagen film was negligible, making it suitable for mimicking the BM of large blood vessels. A leakage test at various volumetric flow rates applied to the microchannels showed no discharge, thereby verifying the reliability of the proposed integrated 2D/3D collagen parts and the contact printing method used for bonding them in the scaffold. In the future, multi-cell culturing will be performed within the 3D porous collagen and against the 2D membrane inside the microchannel, hence preparing this scaffold for studying a variety of blood vessel-tissue interfaces. Also, thicker collagen scaffold tissues will be fabricated by stacking several layers of the proposed scaffold.

Leaks after laparoscopic sleeve gastrectomy: 2024 update on risk factors.

Leaks after sleeve gastrectomy remain a deadly complication significantly affecting outcomes and medical costs. The aim of the present review is to provide an updated decalogue on leak prevention. Risk factors of leakage after LSG were examined based on an extensive review of literature (in period time 2016-2024) and summary of evidence was provided using Oxford levels of evidence scale. Pathogenesis of leakage after LSG still remain related to ischemic and mechanical factors and, therefore, no new evidence has been reported. Conversely, some technical aspect of the procedure has changed: bougie size, antrum resection, staple line reinforcement, and intraoperative leak testing. Bougie size 36F is effective and safe achieving similar leakage rate compared to larger bougie sizes (EL:2) 2024 UPDATE; There is no significant difference in the leak rate between restrictive (< 6cm) and conservative (6cm) antrum resection (EL: 1) 2024 UPDATE; Surgical experience and case volume affect the leak rate more consistently than every kind of SLR (EL: 2) 2024 UPDATE; Intraoperative leak test after LSG represents a decision based on surgeon preference in absence of standardization (endoscopy, bubble test, methylene blue, indocyanine green.) and strong detection/prevention rate (EL: 3) 2024 UPDATE.

Capric-lauric & capric-palmitic/modified bentonite composite as phase change materials for thermal energy storage

This paper proposes a new double layer structure shape-stabilized thermal energy storage wallboard (TESW), by employing microwave radiation modified bentonite (Bm) to stabilize capric acid-lauric acid (CA-LA) and capric acid-palmitic acid (CA-PA) as major components of internal and external wallboard. Leakage test showed that CA-LA/Bm and CA-PA/Bm had good morphological stability. The chemical compatibility, phase change behaviors, and microstructure of CA-LA/Bm and CA-PA/Bm were analyzed. The maximal loading capacities of CA-LA/Bm and CA-PA/Bm can be reached 45 % and 50 %, respectively. In addition, the mechanical and thermal performance of CA-LA/Bm and CA-PA/Bm-based thermal energy storage concrete (CL&CP/Bm-TESC) was systematically studied. The Digital Image Correlation (DIC) technology was used to collect and analyze the speckle images of CL&CP/Bm-TESC20 before and after 100 cycles of phase change, determining the evolution of principal strains during the deformation and failure processes. It is worth noting that the numerical simulation results of the designed double layer structure shape-stabilized CA-LA&CA-PA/Bm-based thermal energy storage wallboard (CL&CP/Bm-TESW) show better temperature adjusting performance. These results demonstrate that the prepared composite of CA-LA/Bm and CA-PA/Bm has potential application in the field of thermal energy storage.

(Invited) Detection, Location and Quantification of H2 Gas Leaks Based on Data Collected with Electrochemical Sensors in a Specifically Designed Test Chamber

Hydrogen is one of the most important energy gases as it is carbon free and therefore can result in the emission reduction of the greenhouse gas CO2. However, hydrogen itself is a secondary greenhouse gas. As a secondary greenhouse gas, hydrogen does not directly add to global warming by entrapping heat. Instead, it reacts with molecules in the atmosphere that are needed to remove the greenhouse gas CH4. CH4 is comparably short-lived in the atmosphere with approximately 10 years compared to CO2 which can last in the atmosphere for centuries. However, CH4 traps at least 100 times as much heat as CO2. Considering the difference in heat capacities of CH4 and CO2, combined with the difference in lifetime, if the same amount of CH4 and CO2 were to be released into the atmosphere at the same time, the global warming effect of CH4 would be approximately 28 times higher than the warming effect of CO2. This means, by releasing hydrogen in the atmosphere, the global warming effect is indirectly enhanced by increasing the lifetime of CH4. Therefore, it is essential to be able to detect, locate and quantify hydrogen leaks right away.Due to the ever-growing hydrogen infrastructure including production facilities, transportation systems like pipelines, as well as storage facilities and user end stations, it is essential to create low-cost, low-power sensors that can be deployed in high numbers. Electrochemical sensors have the potential to fulfill all the needed criteria and are already used for the detection of hydrogen. However, in order to use these sensors to not only detect the leak, but also to locate and quantify the amount of hydrogen that leaked into the atmosphere, additional models and algorithms are needed. To our knowledge, no system currently exists on the market that can be used to fulfill all three tasks.We built a test chamber that enabled us to evaluate H2 leaks and to collect data with electrochemical sensors in a controlled room and environment. The chamber has the size of 800 x 400 x 450 mm3 with a total volume of 144 L. We placed seven of our commercial electrochemical sensors that can detect 0 – 250 ppm hydrogen at different positions inside the box. The box was equipped with one gas inlet and one gas outlet to ensure pressure stability inside the box during our leak test. The inlet was connected to a gas tube which was connected to two mass flow controllers as well as to an outlet tube via a three-way valve. This way, it could be ensured that the gas stream had a stable volume and a constant speed. We released controlled amounts of hydrogen into the box and collected the data with our seven sensors. We were able to see a location-dependent sensor response over time for a 1 second leak of H2 which indicates the capability of such a sensor system to be used for the location of a leak.Quantifying hydrogen is a very complex issue. It requires extremely accurate readings and an intelligent algorithm that is capable to use the reading from multiple sensors and turn that into a mass of hydrogen leaked or leaking. The extremely accurate reading is difficult because the zero and span readouts from the electrochemical sensor is dependent on temperature as well as humidity. This means that the readout zero and span will have to be compensated for both temperature and humidity. While we currently use algorithms to compensate for temperature, we found that these algorithms are not good enough when the sensors are used to measure concentrations in the low-ppm or ppb range. We are researching AI and other computational means to include both temperature and humidity in the compensation algorithms and how including both variables in the compensation process can improve the sensors performance at low concentrations. Both the H2 sensor and its deployment capabilities are technologically and economically significant to the rapidly expanding H2 market for protecting human health, the environment, stemming expensive product losses and promoting efficient use.

Enhancing thermal energy storage properties of blend phase change materials using beeswax.

This study aims to use beeswax, a readily available and cost-effective organic material, as a novel phase change material (PCM) within blends of low-density polyethylene (LDPE) and styrene-b-(ethylene-co-butylene)-b-styrene (SEBS). LDPE and SEBS act as support materials to prevent beeswax leakage. The physicochemical properties of new blended phase change materials (B-PCM) were determined using an X-ray diffractometer and an infrared spectrometer, confirming the absence of a chemical reaction within the materials. A scanning electron microscope was used for microstructural analysis, indicating that the interconnection of the structure allowed better thermal conductivity. Thermal gravimetric analysis revealed enhanced thermal stability for the B-PCM when combined with SEBS, especially within its operating temperature range. Analysis of phase change temperature and latent heat with differential scanning calorimetry showed no major difference in the melting point of the various PCM blends created. During the melting/solidification process, the B-PCMs possess excellent performance as characterized by W70/P30 (112.45J.g-1) > W70/P20/S10 (94.28J.g-1) > W70/P10/S20 (96.21J.g-1) of latent heat storage. Additionally, the blends tend to reduce supercooling compared to pure beeswax. During heating and cooling cycles, the B-PCM exhibited minimal leakage and degradation, especially in blends containing SEBS. In comparison to the rapid temperature drop observed during the cooling process of W70/P30, the temperature decline of W70/P30 was slower and longer, as demonstrated by infrared thermography. The addition of LDPE to the PCM reduced melting time, indicating an improvement in the thermal energy storage reaction time to the demand. According to the obtained findings, increasing the SEBS concentration in the composite increased the thermal stability of the resulting PCM blends significantly. Despite the challenges mentioned earlier, SEBS proved to be an effective encapsulating material for beeswax, whereas LDPE served well as a supporting material. Leak tests were performed to find the ideal mass ratio, and weight loss was analyzed after multiple cycles of cooling and heating at 70°C. The morphology, thermal characteristics, and chemical composition of the beeswax/LDPE/SEBS composite were all examined. Beeswax proves to be a highly effective phase change material for storing thermal energy within LDPE/SEBS blends.

Enhancing non-metallic gasket performance with shape memory fibers

This study aims to enhance the sealing performance of non-metallic gaskets by incorporating shape memory fibers. The analytical exploration focuses on analyzing the thermomechanical behavior of Nitinol fibers in their woven state within the gasket. Specifically, the investigation examines the variation of phase transformation zones across the wire cross-section with changes in temperature. Subsequently, a series of SMA fiber-reinforced gasket samples were fabricated, and experimental investigations were conducted to assess the impact of Nitinol fibers on composite gaskets using a helium gas leak test. The results demonstrate that the integration of shape memory alloy wires into the composition of gaskets can significantly improve their sealing performance. Moreover, this study examines a number of pivotal factors such as fiber volume fraction, temperature application, woven fiber arrangement, leakage rates, gasket deformation, contact stress, and structural bending. These comprehensive investigations may provide valuable insights into the efficacy of Nitinol fibers in enhancing gasket sealing performance.

Multi-modality hierarchical attention networks for defect identification in pipeline MFL detection

Abstract Magnetic flux leakage (MFL) testing is widely used for acquiring MFL signals to detect pipeline defects, and data-driven approaches have been effectively investigated for MFL defect identification. However, with the increasing complexity of pipeline defects, current methods are constrained by the incomplete information from single modal data, which fail to meet detection requirements. Moreover, the incorporation of multimodal MFL data results in feature redundancy. Therefore, the multi-modality hierarchical attention networks (MMHAN) are proposed for defect identification. Firstly, stacked residual blocks with cross-level attention module (CLAM) and multiscale 1D-CNNs with multiscale attention module are utilized to extract multiscale defect features. Secondly, the multi-modality feature enhancement attention module (MMFEAM) is developed to enhance critical defect features by leveraging correlations among multimodal features. Lastly, the multi-modality feature fusion attention module (MMFFAM) is designed to dynamically integrate multimodal features deeply, utilizing the consistency and complementarity of multimodal information. Extensive experiments were conducted on multimodal pipeline datasets to assess the proposed MMHAN. The experimental results demonstrate that MMHAN achieves a higher identification accuracy, validating its exceptional performance.

Endobronchial Closure for Peripheral Pulmonary Air Leakage

Introduction: A minimally invasive alternative to surgery for treating pneumothorax has been developed, aiming to reduce risks while maintaining efficacy. This study conducted basic experiments using ex vivo and in vivo pig lung employing a super-thin catheter for treatment. This new device injects fibrin glue directly into the responsible lesion to close the air leak, which has two features: thin design and double-lumen. Methods: The experimental setup involved utilizing trachea and both lung specimens from pigs under positive pressure ventilation. To simulate pneumothorax, artificial fistulas were created on the lung surfaces. The super-thin catheter, guided through a bronchoscope near the fistula, was used to embolize the peripheral bronchus by injecting a fibrin preparation. Then, an air leak test was conducted afterward to assess the efficacy of the treatment. Additionally, a similar pneumothorax model was induced in alive pig under general anesthesia to evaluate its curability. Results: In the extracted pig lungs, embolization was performed in 21 cases, resulting in the cessation of air leaks in 19 cases, corresponding to a 90.5% cure rate. Notably, no major adverse events occurred with the treatment devices. Similarly, in living pigs, pneumothorax was successfully treated, with no recurrence observed up to the seventh postoperative day. Conclusion: The novel treatment device utilizing a super-thin catheter offers a minimally invasive and highly curative option for pneumothorax. These promising results suggest the potential for further development and human clinical trials, which could revolutionize the treatment of pneumothorax, reducing risks and improving outcomes.

A Non-Metallic pipeline leak size recognition method based on CWT acoustic image transformation and CNN

Accurately identifying the pipeline leak size is crucial for risk assessment and timely rescue. In this study, a Convolutional Neural Network (CNN) based on Continuous Wavelet Transform (CWT) acoustic image transformation is proposed to identify small-sized leak in non-metallic pipes. Firstly, one-dimensional acoustic signals are filtered using the Piecewise Aggregate Approximation (PAA) algorithm to reduce noise and storage resource consumption. Then, the filtered signals are transformed into two-dimensional images by CWT to enrich signal feature information, serving as the input for the CNN. Further, a leak size recognition model based on CWT-CNN is established. The effectiveness of this model is verified using experimental data from a non-metallic pipeline leak test. A comparative analysis is conducted on diverse acoustic image transformation methods, including CWT, Gramian Angular Summation Field (GASF), and Relative Position Matrix (RPM). The results demonstrate the superiority of the CWT-CNN model in pipeline leak size recognition. Finally, the impact of the signal length in an acoustic image on recognition accuracy is also examined. The results demonstrate that when the signal length in an acoustic image is 0.75 s, the accuracy obtained by CWT-CNN can reach 95 %.