Presence Of Leak Research Articles

Role of ventilator and nasal interface in pressure transmission during neonatal intermittent positive pressure ventilation: A bench study.

We aimed at evaluating pressure transmission and stability during non-synchronized neonatal nasal intermittent positive pressure ventilation (NIPPV) delivered using five mechanical ventilators and three nasal interfaces. An artificial nose-throat model was connected to a mechanical analog of the infant respiratory system and a breath generator. Ventilation was administrated via a nasal mask (NM), short bi-nasal prongs (SBN), or RAM® cannula. We applied positive end-expiratory pressures (PEEP) of 5 and 10 cmH2 O, inspiratory pressures (PIP) of 15 and 30 cmH2 O, inspiratory times of 0.23, 0.42, and 0.57 s. Measurements were performed with leaks of 0, 1.5, and 4 L/min. The pressure was measured at the airways opening (PAW ) and the glottis (PGL ).The difference between set and delivered pressures (PAW ) was less than ±1 cmH2 O for all ventilators. We documented a significant difference between PAW and PGL in the presence of leaks. With 4 L/min leaks, PEEP dropped by 43%, 49%, and 63% with NM, SBP, and RAM® cannula, respectively; PIP dropped by 58%, 64%, and 74%. On average, the SD of PEEP fluctuations was ±0.60 and ±2.50 cmH2 O for PAW and PGL ; the breath-by-breath SD of PIP was ±0.77 and ±2.06 cmH2 O. During NIPPV, the PIP and PEEP transmission to the glottis is markedly lower than the set values and highly variable. The impact of leaks and nasal interface is much more significant than the differences in ventilators' performance on the efficacy of pressure transmission and stability of non-synchronized ventilator-generated NIPPV.

Technical Performance of Continuous Pressure Insufflators Versus Traditional Insufflators in the Presence of Leaks During Laparoscopic Surgery.

Background. New insufflators have been developed to manage leaks emanating from the working cavity during laparoscopic surgery. Little data have been published to show the performance of these insufflators. This study evaluates the performance of 2 modern continuous pressure insufflators in various leak conditions. Methods. Performance of a new continuous pressure insufflator, EVA15 (Palliare, Galway, Ireland), was compared with that of a continuous pressure insufflator, Airseal intelligent Flow System (iFS) (CONMED, Utica, NY), and a traditional intermittent pressure insufflator, Endoflator 40 (KARL STORZ, Tuttlingen, Germany). Six different leak scenarios were created in a swine model to create different dynamic leak profiles of between 5 and 15L/min. Pressure deviation from setting was measured for each insufflator tested. The following were calculated: (a) mean absolute difference of measured insufflation pressure vs. the insufflator pressure setting for the 50second measurement period (MAD) and (b) standard deviation of the absolute differences (SD). Results. The average mean absolute pressure difference between the EVA15 and Airseal is .27mmHg. However, the average mean absolute pressure difference between the EVA15 and Endoflator 40 is 2.62mmHg. Conclusions. Continuous pressure insufflators provide superior pressure delivery performance in leak situations when compared against a traditional intermittent pressure insufflator. No clinically significant performance difference was observed when comparing the EVA15 and Airseal iFS insufflators in the tested leak situations.

Effectiveness of face masks for the population.

Health authorities and organizations consider non-medical face masks as an additional passive means to prevent virus diffusion. Communication strategies disseminate information among the population that such masks are essential for mitigating virus diffusion. However, scientific studies are not conclusive in showing the undisputed filtration efficiency of fabric/cloth facial masks (both commercial and homemade). This study examines scientific data about the effectiveness of face masks before and during the COVID-19 emergency. Present trends in the making of commercial and homemade fabric/cloth face masks are also examined. Statistical data of published studies are analyzed and compared. Main considerations and sugge-stions are also extracted and discussed. Current approaches are examined for assessing the characteristics and effectiveness of fabric/cloth commercial and homemade face masks intended for the population. Conflicting data exist as to whether non-medical masks have a protective effect from the spread of respiratory viruses. Both medical masks (MDs) and respiratory personal protection equipment (PPE) show a given effectiveness value. Concerning commercial and homemade fabric/cloth masks, giving general indications on the choice of materials and their assemblage is difficult as it is not possible to assess the effectiveness of the filter media with respect to the kind of multiphase fluid that may be emitted upon breathing, sneezing, or coughing under different environmental conditions. This is particularly important because airflow rate, temperature, humidity, and duration of use will affect the performance of filter media. Moreover, while a mask may have excellent filter media, droplets may leak into the face-piece unless there is an adequate facial seal. In the presence of leaks, any type of mask may actually offer less protection independently of its nominal filtering effìciency.

Prelocalization and leak detection in drinking water distribution networks using modeling-based algorithms: a case study for the city of Casablanca (Morocco)

Abstract. The role of a drinking water distribution network (DWDN) is to supply high-quality water at the necessary pressure at various times of the day for several consumption scenarios. Locating and identifying water leakage areas has become a major concern for managers of the water supply, to optimize and improve constancy of supply. In this paper, we present the results of field research conducted to detect and to locate leaks in the DWDN focusing on the resolution of the Fixed And Variable Area Discharge (FAVAD) equation by use of the prediction algorithms in conjunction with hydraulic modeling and the Geographical Information System (GIS). The leak localization method is applied in the oldest part of Casablanca. We have used, in this research, two methodologies in different leak episodes: (i) the first episode is based on a simulation of artificial leaks on the MATLAB platform using the EPANET code to establish a database of pressures that describes the network's behavior in the presence of leaks. The data thus established have been fed into a machine learning algorithm called random forest, which will forecast the leakage rate and its location in the network; (ii) the second was field-testing a real simulation of artificial leaks by opening and closing of hydrants, on different locations with a leak size of 6 and 17 L s−1. The two methods converged to comparable results. The leak position is spotted within a 100 m radius of the actual leaks.

Uniformly optimal multi-sensor design in pipe networks for transient-based leakage localization

The design of sensor placement in water supply pipe networks for the purpose of transient-based leakage localization is investigated. Each sensor is placed at where the Fisher information of measurement concerning leaks is maximized; equivalently, the Cramér–Rao lower bound (CRLB) representing the lower limit of leak localization error is minimized. An explicit algorithm for computing the CRLB with respect to leak parameters in a general pipe network is developed. The presence of leak is considered as stochastic and modeled in a probabilistic framework by assuming that the leak location follows a probabilistic distribution with a support on the whole network. The optimal distribution of the sensors is then computed via a quasi-Monte-Carlo simulation, where the expectation of the CRLB of leak localization error is minimized. The proposed sensor placement methodology is optimal uniformly over all the leak localization methods, all the potential sensor locations and all the situations of leaks. Four examples from a simple single-pipe system to a complex pipe network are presented to illustrate the proposed methodology.

Time windows: The key to improving the early detection of fuel leaks in petrol stations

In this paper, the authors propose the use of time windows to improve the detection of fuel leaks in petrol stations. They employ two-class supervised classifiers that work with feature sets containing representative variables taken from station inventory books that indicate the presence of leaks. Fuel leaks in petrol stations with underground tanks pose a serious problem from an environmental standpoint. Large leaks are very evident, and are therefore detected quickly without the need to use a specific procedure. Small leaks, however, tend to go unnoticed, and if no detection techniques are employed, they are only identified once environmental damage has been done. This makes detecting the leak in the shortest time possible as important as ascertaining when the leak started. The authors show how the use of time windows, which entails having the classifier work with information accumulated over several days, can be used to efficiently resolve the proposed problem, fully complying with the applicable regulation.

Harmonic oscillator tank: A new method for leakage and energy reduction in a water distribution network with pressure driven demand

It is now well established that rate of leakage of water is directly related to the distribution pressure in a network. In this context, pumps can consume up to 60% of the overall energy requirement in the case of pressure driven demand whereby they are solicited for direct supply. In this paper, we investigate the energy efficiency of distribution in an experimental network which is embedded with two levels of leakage (low and high) using three different methods. They are analysed and compared in terms of specific energy consumption and rate of leakage. A novel concept known as the Harmonic Oscillator Tank has been developed whereby the conventional hydropneumatic tank is pressure modulated so as to produce a constant output flowrate within the presence of leaks. Experimental results show that the throughput of the Harmonic Oscillator Tank for a heavy leaking network is highest (86.45%) with the lowest percentage leakage of 13.5% at a specific energy consumption of only 0.354 kWh/m3/day when compared to the other two schemes namely direct pumping and pumping through a variable speed drive in a loop. This Harmonic Oscillator Tank opens up new avenues for reducing energy and leakage in old damaged networks whereby a short or medium-term solution is often required since infrastructure renewal requires time and a massive investment.

Leak-Diagnosis Approach for Water Distribution Networks based on a k-NN Classification Algorithm

This paper proposes an approach based on a k-Nearest Neighbour classification algorithm (k-NN) to identify regions in a water distribution network (WDN) that are affected under presence of leaks. The classification algorithm is trained with numerical data coming from a MATLAB simulator based on a dynamic model of the WDN that involve leaks in its formulation. Concretely, the training is done by using the numerical solutions of a dynamic model of the WDN under several leak cases. The dynamic model is formulated by taking into account typical assumptions of the rigid water column (RWC) theory and using the graph theory. The proposed approach was evaluated in a hydraulic pilot plant.

Development of automated analytical systems for physical and chemical parameters of petroleum products

New devices have been developed for measuring the mass of petroleum products in vertical cylindrical tanks. As a parameter by which to judge the presence of leaks in the tanks, it is proposed to use the change in the mass of the controlled product over time. Special software is used to analyze the obtained measurement results and diagnose the presence and magnitude of leakage.

Very Low Crosstalk Measurement of Substrate Integrated Coaxial Line (SICL)

When designing a microwave circuit involving substrate integrated coaxial lines (SICLs), it is important to know what real crosstalk between SICLs is. A measured crosstalk will be a good reference value in a practical design. In addition, it is also needed to compare and check the crosstalk from the simulation and calculation formula with measured results. However, it is very difficult to measure the crosstalk between SICLs because it is theoretically very low. In this study, for the first time, the crosstalk characteristics of a SICL are evaluated through experimental design and measurements. By adjusting the layout of the structures and implementing controlled experiments, interference caused by the presence of leaks and radiation at the interface and structural transitions is effectively suppressed. The experimental results show that for two parallel SICLs with a length of 30 mm and an interval of 5 mm, the isolation is greater than 80 dB for the measured frequency range of 1–8 GHz, significantly better than the results of the grounded coplanar waveguide (GCPW).

Rapid Diagnostic Test Kit for Point-of-Care Cerebrospinal Fluid Leak Detection.

Cerebrospinal fluid (CSF) leaks can occur when there is communication between the intracranial cavities and the external environment. They are a common and serious complication of numerous procedures in otolaryngology, and if not treated, persistent leaks can increase a patient's risk of developing life-threatening complications such as meningitis. As it is not uncommon for patients to exhibit increased secretions postoperatively, distinguishing normal secretions from those containing CSF can be difficult. Currently, there are no proven, available tests that allow a medical provider concerned about a CSF leak to inexpensively, rapidly, and noninvasively rule out the presence of a leak. The gold standard laboratory-based test requires that a sample be sent to a tertiary site for analysis, where days to weeks may pass before results return. To address this, our group recently developed a semiquantitative, barcode-style lateral-flow immunoassay (LFA) for the quantification of the beta-trace protein, which has been reported to be an indicator of the presence of CSF leaks. In the work presented here, we created a rapid diagnostic test kit composed of our LFA, a collection swab, dilution buffers, disposable pipettes, and instructions. Validation studies demonstrated excellent predictive capabilities of this kit in distinguishing between clinical specimens containing CSF and those that did not. Our diagnostic kit for CSF leak detection can be operated by an untrained user, does not require any external equipment, and can be performed in approximately 20 min, making it well suited for use at the point of care. This kit has the potential to transform patient outcomes.

ВЛИЯНИЕ ПРОТЕЧЕК РАБОЧЕГО ТЕЛА НА КООРДИНАТУ ТОЧКИ МАКСИМАЛЬНОГО РОСТА ДАВЛЕНИЯ СЖАТИЯ

The article discusses the analysis of the parameters of the compression process, which is carried out according to the results of engine indication. The solution to this problem allows us to evaluate the technical condition of the cylinder-piston group parts. According to the requirements of most classification societies, the deviation of the compression pressure on this cylinder from the engine average should not exceed 2.5%. The dependence of the compression pressure value on the pressure of the supercharger makes it difficult to obtain correct diagnostic conclusions about the condition of the cylinder-piston group when the technical condition of the gas turbine compressor deteriorates. The existing publications investigated the position on the indicator diagram of the point at which the rate of increase in compression pressure reaches its maximum, and its position was demonstrated to be almost invariant with respect to pressure. This fact makes it possible to calculate its position relative to the top dead center of the engine even before the start of indexing and to accept the calculated value as a first approximation in the algorithmic synchronization of the display results. However, the leakage of the working medium, inevitably present in the engine, was not considered. Therefore, the problem of the displacement of the coordinate point of the maximum rate of pressure increase in the presence of leaks is legitimate. The task is solved applying a mathematical model consisting of three equations (condition, mass conservation and the first law of thermodynamics), written in a differential form and integrate at each calculated step. As an argument, the selected angle of rotation of the crankshaft of the engine. Nevertheless, to solve such systems of equations analytically considering the leaks in the full formulation is extremely difficult. Therefore the effective flow area of the piston rings was given in modeling the workflow is considered to be constant throughout the calculations. The modeling results determine the position of the point of maximum pressure rise rate on the indicator diagram, which can be used as an indirect indicator in the integral analysis of the engine technical condition

401 - Does the presence of leak on the peri-catheter urethrogram affect the short term outcomes of urethroplasty?

401 - Does the presence of leak on the peri-catheter urethrogram affect the short term outcomes of urethroplasty?

Impact of leaks and ventilation parameters on the efficacy of humidifiers during home ventilation for tracheostomized patients: a bench study

BackgroundDuring invasive ventilation, the upper airway is bypassed and no longer participates in humidification of inspired gases, which is essential to avoid harmful consequences such as endotracheal tube occlusion. In the case of increased air flow, especially in the presence of leaks (intentional or unintentional), the humidification provided by humidifiers may become ineffective. The objective of this bench study was to evaluate the quality of humidification provided by heated humidifiers under various home ventilation conditions.MethodsFive heated humidifiers were tested in eight configurations combining circuit (expiratory valve or vented circuit), tidal volume (600 or 1000 mL) and presence of unintentional leak. Absolute humidity (AH) was measured at the upstream of the test lungs, which were placed in a 34 °C environmental chamber in order to simulate body temperature.ResultsThe AH measured in the valve circuit ranged between 30 mg/L and 40 mg/L and three out of the five humidifiers achieved an AH higher than the recommended level (33 mg/L). With the vented circuit without unintentional leak, when tidal volume was set at 600 mL, all humidifiers reached an AH higher than 33 mg/L except one device; when the tidal volume was set at 1000 mL and unintentional leak was present, four out of the five humidifiers provided an AH lower than 33 mg/L.ConclusionThis study shows that, except under certain home ventilation conditions, such as high tidal volumes with unintentional leak in vented circuit, most heated humidifiers ensure sufficient humidification to avoid the risk of side effect in patients.

Leak detection in low-pressure gas distribution networks by probabilistic methods

The presence of leaks is a prevalent issue for aging gas distribution systems across the globe. These events, if not detected in time, may bring about environmental and health hazards, besides economic losses. Therefore, the development of efficient detection, quantification, and localization methods is crucial to all gas companies worldwide. In this paper, we present a leak monitoring system, called Leak Analytics System (LAS) using a probabilistic approach to determine the location and the rate (severity) of leakage in low-pressure gas distribution networks. This work aims to develop a robust, cost-effective, and real-time online monitoring system for low-pressure gas distribution networks. The leakage events are estimated using pressure and flow data obtained from steady-state modeling of the gas network. The robustness of the methodology is illustrated by analyzing gas networks in the presence of measurement errors, which account for unavoidable sensor noise in flow and pressure data. The feasibility of the proposed method is demonstrated on a small artificial gas network. Moreover, the method is applied to a section of the Singapore gas distribution network for a single as well as multiple leak scenarios. It is also experimentally shown that the severity of the leak and the location for a single leak scenario can be determined within an accuracy of 95% and 80% respectively, even in the presence of strong noise.

Evaluation of Software-Based Early Leak-Warning System in Gulf of Mexico Subsea Flowlines

SummaryEarly detection of subsea pipeline leaks is a very serious and ongoing issue for the oil and gas industry with limited successful cases reported. For example, aerial surveillance of pipelines can be applied only for relatively shallow and concentrated areas, and an advanced technology such as fiber-optic cable can be considered at the significant expense of time and cost for installation and equipment. The objective of this study is to evaluate a software-based leak-detection technique through complex multiphase flow mechanics. More specifically, this study investigates (i) how leak-detection problems can be formulated from a fluid-mechanics viewpoint and (ii) how reliable such a technique can be under conditions resembling the deepwater Gulf of Mexico (GOM). In examining a wide range of scenarios, this study proves that software-based techniques have a potential for playing a key role in the future.First, this study defines a base case selected from the literature review of deepwater GOM flowlines in terms of pressure and temperature conditions, fluid properties, reservoir properties, and flowline characteristics that allows a steady-state flow in pipeline to be determined with no leak present. Next, leaks with certain opening sizes (dleak) at different longitudinal locations (xD = x/L) are positioned, and new steady states in the presence of leaks are calculated. By comparing the two steady-state responses (with and without leak), finally, the changes in two leak-detection indicators [i.e., change in upstream pressure (ΔPin) and change in downstream total flow rate (Δqt out)] can be calculated in a wide range of input parameters. This study presents the results in the form of contour plots for pressure and flow responses.The major finding of this study is that, theoretically, it is possible to estimate both size and longitudinal location of the leak with the two leak-detection indicators in the software-based leak-detection method. The results from various subsea flowline conditions [such as different gas/oil ratios (GORs) and fluid types, water depths, pressures at the receiving facilities, inclination angles, pipe diameters, water cuts, and so on] show that the reliability of this technique is improved when the sink term (i.e., amount of leaking fluid) is more dominant, which, in turn, means that leaks positioned farther upstream, with larger opening size, and occurring at higher pressure inside pipe are relatively easier to detect. In many of the scenarios considered, Δqt out as a leak-detection indicator shows more than a 10% change in the presence of a leak with dleak>1 in., allowing relatively easier activation of a leak-warning system, which demonstrates the robustness of this technique. Other scenarios in which the indicators are less than a few percent changes, however, may be challenging—in those cases, additional responses from other methods (hardware-based or transient simulation) will be helpful.

NON-DESTRUCTIVE LEAK DETECTION IN GALVANIZED IRON PIPE USING NONLINEAR ACOUSTIC MODULATION METHOD

Non-destructive testing is a wide group of analysis techniques used in science and industry to evaluate the properties of a structure without causing damage to it. The main objective of this project is to carry out experiment to detect leakage in pipeline using nonlinear acoustic modulation method. The nonlinear acoustic modulation approach with low frequency excitation and high frequency acoustic wave is used to reveal modulations in the presence of leak. The pipe used in this experiment was galvanized iron pipe. The experiment is started with the experiment of undamaged specimen and followed by the experiment of damaged specimen with manually applied leak. The results obtained are being observed and the difference between the specimen without leak and with leak can be distinguished. The distance of the leak and the distance of the outlet detected is nearly accurate to the exact location which is leak at 4.0 m and outlet at 6.0 m. Therefore, the results demonstrate that leakage can be detected using nonlinear acoustic modulation, and proved the objective of distinguish the difference between the results of specimen without leak and with leak has succeeded. The damage detection process can be eased with the knowledge on the signal features.

Leak Detection in Water Collection and Transmission Networks Using the Minimum Nodal Pressure Measurement

Leak has always been one of the problems in water distribution networks, whose preventing not only results in the saving of water sources but also has profound effects on the maintenance cost of networks. In the present paper, a new method is applied for leak detection in water collection and transmission network. In this method, detection of leak location is performed by pressure difference analysis at junctions and by the help of the relative index of the leak. The pressure measurements should be performed at least at two nodes for two cases of with and without the presence of leak. The minimum number of pressure measurements to form a relative leak index is two. However, in this case, two nodal pressure measurements are too few, and the number of pressure measurement should be increased. Therefore the next option for the number of measurements is three. The investigated network in this research includes 7 wells with an approximate length of 7800 m located in the northwestern city of Mashhad. A real leak with a rate of 7.57 l/s is created at one of the network nodes whose amount is measurable by a volume counter. The real leak is a hypothetical leak which is known in advance, and its magnitude is not necessarily a round number in term of a liter per second. Finally, this leak is identified by the proposed method via 3 nodal pressure measurements.

Endoscopic enteral accesses: Review article

A benefit of enteral nutritional support over the parenteral for acute and chronic diseases has been observed because it is more physiological and is associated with fewer complications. The most frequently used for this purpose are nasoenterals feeding tubes lasting no more than 30 days and percutaneous accesses involving longterm feeding. Prepiloric feeding is appropriate for most critical patients. However, postpiloric feeding, which is achieved with nasojejunal probes, percutaneous endoscopic gastrostomy with jejunal extension (PEG-J) and jejunostomy is indicated for those with regurgitation, aspiration of gastric foods or presence of leaks in the upper tractodigestive. There are several methods for the placement of enteral accesses, the endoscopic being the first choice in most cases, leaving the one performed by radiointervention and surgical for the technically difficult cases. There are advances with new endoscopic techniques such as endoscopic percutaneous jejunostomy by double balloon enteroscopy (PEJ) and endoscopic ultrasound in pacemakers with modified anatomy (Y-Roux) and excluded stomach, as well as the placement of selfexpanding metal prostheses at the duodenal or gastrojejunostomy by endoscopic ultrasound assisted by fluoroscopy guided by double balloon intestinal occlusion in cases of obstruction to the outflow tract by neoplasia. Due to the above, based on patient characteristics and prognosis, there are already more endoscopic options to preserve the enteral route as the main nutritional route in patients with chronic diseases.

0551 BILEVEL PAP EXPERIENCE IN A COMMUNITY SLEEP CENTER

Bilevel titration in OSA is used for patients with CPAP intolerance, or for incomplete correction with maximal CPAP pressure. We present our one year experience with BiLevel use in a community sleep lab. Retrospective data evaluation of all Bilevel patients. Patients undergoing re-titration were excluded from the study. Variables measured included demographics, comorbidities, baseline RDI and titration RDI, use of supplemental oxygen, type of device and interface, presence of leaks, patient’s subjective sensation of sleepiness (ESS), average REM percentage, and time spent under 90% and 88% of oxygen saturation. Patients were subdivided into four subgroups based on lowest achieved RDI: Excellent with RDI < 5, Good RDI < 10, Fair RDI < 15, and Poor with RDI > 15. Of the 133 patients who underwent Bilevel titration, 73 (55%) had excellent RDI, 25 (19%) good RDI, 14 (10%) fair RDI, and 21 (16%) had a poor RDI. In comparison to the excellent RDI group, patients in the poor RDI group had higher overall post RDI and ESS, arousal index, oral leaks, treatment emergent events and central apnea index. They had lower sleep efficiency and spent more time under O2 saturation of 88% (24% vs 17%). Although they had a higher percentage of patients with no leaks, they still had an overall higher percentage of oral leaks. No difference was noted with device type or interface used. 1. 16% of patients did not achieve effective pressure on the first night of titration. 2. As a group they had lower sleep efficiency, higher arousal index, and spent increased time under 88% oxygen saturation. 3 . Oral leaks may have played a role. 4. Would analyse if ineffective EPAP played any role. None.