Source Of Leakage Research Articles

Does crude oil output aid economy boom or curse in Nigeria? An inference from “Dutch disease”

PurposeA reflection on some supposed oil exporting states constantly reminds of the (in) validity of the resource curse hypothesis and environmental consequences of oil exploration. In Africa, especially the case of Nigeria, the argument has remained whether the country's voluminous deposit of crude oil has positively affected the livelihood of the people. The study aims to examine the impact of oil production on the income level in Nigeria.Design/methodology/approachIn this context, the study first examined validity of Dutch disease in Nigeria, thus providing a foundation to further establish the resource curse hypothesis. As such, the impact of crude oil production (CRUDE), square of crude oil production (CRUDESQ), crude oil reserves (RESERVES) and population (POP) on economic growth over the period of 1980–2018 is examined through the combination of autoregressive distributed lag (ARDL), fully-modified ordinary least square (FMOLS) and canonical cointegration regression (CCR) methods.FindingsWhile the study revealed the existence of Dutch disease in Nigeria, the resource curse hypothesis is also valid. However, the study found that the resource curse hypothesis in Nigeria can be over-turned when the CRUDE attains a certain maximum threshold, i.e. when crude oil output is doubled over time. In addition, either of crude RESERVES or oil rent (RENT) is seen as a limiting factor to economic growth while POP poses a positive and desirable impact on the country's economic development.Originality/valueThus, the implication of a U-shaped relationship between oil production and income level is that Nigeria's natural resources exploration could be employed to over-turn the potential of resource curse hypothesis by increasing exploration while the sources of leakages and misappropriation of the oil revenues are deliberately mitigated. Other useful socio-economic policies were proposed for the Government.

Novelty Messages Filtering for Multi Agent Privacy-Preserving Plannin

In multi-agent planning, agents jointly compute a plan that achieves mutual goals, keeping certain information private to the individual agents. Agents' coordination is achieved through the transmission of messages, but they can be a source of privacy leakage as they can permit a malicious agent to collect information about other agents' search processes and states. In this paper, we investigate the usage of novelty techniques in the context of (decentralised) multi-agent privacy preserving planning, addressing the challenges related to the agents' privacy and performance. In particular, we show that novelty based techniques allow a significant reduction on the number of messages transmitted among agents, increasing their privacy levels and also their performances. An experimental study analyses the effectiveness of our techniques and compares them with the state of-the-art. Finally, we examine the robustness of our approach considering different delays in the messages transmission as would occur in overloaded networks, due for example to massive attacks or critical situations.

Vacuum leakage location based on cross-correlation wavenumber domain imaging method with a 64-element ultrasonic sensor array.

Vacuum leakage is extremely harmful to aircraft and needs to be discovered as soon as possible. Aiming at the problem of vacuum leakage location, this paper proposes a cross-correlation wavenumber domain imaging method. This method obtains the time-space domain information of the leakage elastic wave through the array sensor and transforms it into the frequency-wavenumber domain through the three-dimensional Fourier transform. The direction of the maximum value of the wavenumber vector represents the direction of the leakage source. In the algorithm, the cross-correlation operation is added, and the synchronous acquisition of multiple array elements is replaced by the polling scan method, which greatly improves the possibility of the realization of the algorithm. A 64-element ultrasonic sensor was fabricated and the method was verified. The results show that the method proposed in this paper can realize the continuous leakage signal direction of the planar structure and is applicable to the leakage holes of different apertures, and it has the potential for application on orbiting spacecraft and aircraft.

Risk identification and technical modifications reduce the incidence of post-cholecystectomy bile leakage: analysis of 5675 laparoscopic cholecystectomies

PurposeThe main sources of post-cholecystectomy bile leakage (PCBL) not involving major duct injuries are the cystic duct and subvesical/hepatocystic ducts. Of the many studies on the diagnosis and management of PCBL, few addressed measures to avoid this serious complication. The aim of this study was to examine the causes and mechanisms leading to PCBL and to evaluate the effects of specific preventative strategies.MethodsA prospectively maintained database of 5675 consecutive laparoscopic cholecystectomies was analysed. Risk factors for post-cholecystectomy bile leakage were identified and documented and technical modifications and strategies were adopted to prevent this complication. The incidence, causes and management of patients who suffered bile leaks were studied and their preoperative characteristics, operative data and postoperative outcomes were compared with patients where potential risks were identified and PCBL avoided and with the rest of the series.ResultsTwenty-five patients (0.4%) had PCBL (7 expected and less than half requiring reintervention): 11 from cystic ducts (0.2%), 3 from subvesical ducts (0.05%) and 11 from unconfirmed sources (0.2%). The incidence of cystic duct leakage was significantly lower with ties (0.15%) than with clips (0.7%). Fifty-two percent had difficulty grades IV or V, 36% had empyema or acute cholecystitis and 16% had contracted gallbladders. Twelve patients required 17 reinterventions before PCBL resolved; 7 percutaneous drainage, 6 ERCP and 4 relaparoscopy. The median hospital stay was 17 days with no mortality. Hepatocystic ducts were encountered in 72 patients (1.3%) and were secured with loops (54.2%), ties (25%) or sutures (20.8%) with no PCBL. Eighteen sectoral ducts were identified and secured.ConclusionLigation of the cystic duct reduces the incidence of PCBL resulting from dislodged endoclips. Careful blunt dissection in the proper anatomical planes avoiding direct or thermal injury to subvesical and sectoral ducts and a policy of actively searching for hepatocystic ducts during gallbladder separation to identify and secure them can reduce bile leakage from such ducts.

Federated learning based atmospheric source term estimation in urban environments

Establishing an accurate and efficient source term estimation (STE) system is of great significance for identifying unknown gas leakage sources in urban environments. Many successful STE methods have been proposed, while most of them assume there is only one point source. However, the complicated urban atmospheric dispersion and the massive sensor data in distributed edge devices pose new challenges. To address these issues, this paper proposes a method to convert measured concentrations into visual features, which retains the characteristics of diffusion and the layout of obstacles. Then, a federated STE (FL-STE) framework is proposed to extract knowledge from local models collaboratively without collecting all privacy data, in which a deep neural network is used to recognize the relationship between visual features and source terms. Furthermore, we construct an urban dispersion dataset with multiple obstacles and sources by FDS simulation. Various empirical studies prove the efficiency of the proposed method.

Probabilistic human health-risk assessment and influencing factors of aromatic hydrocarbon in groundwater near urban industrial complexes in Northeast China

Organic pollutants are common in the environment, very difficult to remove, and pose a serious threat to human health. Probabilistic risk assessment advances conservative single-point estimation and brings a new perspective to risk assessment. From 2009 to 2019, we monitored the distribution of major pollutants in an industrial park in Northeastern China. The result showed the maximum concentration of benzene reached 73,680 μg/L in 2009, benzo[a]pyrene reached 36.80 ng/L in 2016. These concentrations are significantly above the levels set by Chinese regulatory agencies. The single-factor index increases year by year, and pollutants gradually spread from the pollution leakage source to surrounding areas. A new method was used to quantify the human health risk from groundwater organic pollution accurately, based on the triangular fuzzy numbers coupled with the Monte Carlo simulation. The Monte Carlo simulation was used to simulate the triangular fuzzy numbers. This simplified the operation between the triangular fuzzy numbers and their function successfully and obtained the risk as a set of values. The results indicated that non-carcinogenic risk was negligible in all age groups (children, adolescents, and adults). Conversely, when it comes to carcinogenic risks, adults were about 50–270 times the tolerable level of risk due to long exposure years and wide skin contact areas. Oral ingestion played an essential role in total exposure (>90%) compared to dermal contact. Control of exposure duration and intake should be prioritized when making decisions to reduce risk uncertainty. Monte Carlo simulation–triangular fuzzy numbers can effectively reduce the risk of uncertainty and reflect the complex conditions of the groundwater environment for small amounts of data or inaccurate data.

Emission source tracing based on bionic algorithm mobile sensors with artificial olfactory system

AbstractThe leakage of hazardous chemicals and toxic volatile substances in the atmosphere may cause serious consequences such as explosion and poisoning. To identify the unknown leakage locations and gas compositions, a mobile robot system to trace the leak source in the outdoor was investigated. First, two bionic searching algorithms, Zigzag and Silkworm algorithms, were tested with outdoor experiments for locating the leak source. The results showed that the locating errors of these two algorithms were within 0.5 m in 10 by 20 m search space, but the failing ratio of Zigzag and Silkworm algorithm was still high (about 40–50%). Therefore, an improved tracing algorithm combining the Silkworm and Zigzag algorithm, called as zigzag–Silkworm algorithm, was proposed. Compared with Silkworm and Zigzag algorithms, zigzag–Silkworm algorithm had a higher success ratio of 80% in outdoor source tracing tests, and the searching efficiency was enhanced, the efficiency parameter L: L0 has improved from 2.58 for Silkworm and 2.66 for Zigzag to 2.17 for zigzag–Silkworm. Then, in order to identify the composition of the leaked gases during the source tracing, an artificial olfaction system (AOS) based on the gas sensor array and support vector machine was set on the mobile robot. The test results in the source tracing experiments with ammonia and ethanol emissions indicated that the recognition accuracy of emission gases reached to 99% with AOS equipped on the robot. Therefore, the mobile robot system equipped with the zigzag–Silkworm algorithm and the AOS is feasible to trace the leakage source and identify the emission composition in the outdoor leakage event with good performance in efficiency and accuracy although some underlying problems still need to be addressed in future work.

Flexible and Modular Fully Metallic Housing Concept for Solid Oxide Fuel Cells

The state-of-the-art alumina oxide housings used in single cell test rigs are fragile, inflexible and expensive. They are designed for a specific cell geometry, a change of the cell type - changing the cell thickness - or a change in the cell size is not intended and is thus associated with an immense expenditure of effort and time. In detail, the state-of-the-art ceramic frame concept is vulnerable to a fracturing of the frame or an insufficient contacting of the cell if a change in the cell thickness occurs. The connection of the ceramic housing with the typically metallic tubing of the gas supply is fragile, prone to develop leakages and is time consuming to replace and thereby prevents a change of the cell size. Gold wire seals used at the cathode side are a common source of leakage. Furthermore, the whole ceramic housing is sensitive to fracturing due thermal or load induced stress, and thus prevents fast thermal cycling of the specimen.This paper presents a modular, fully metallic housing concept which enables a fast and easy change of the cell size due to the utilization of a baseplate and a robustness towards different cell thicknesses due to the usage of a flexible metallic frame. The utilization of metal instead of alumina oxide reduces the manufacturing costs. Furthermore, an additional sealing on the cathode side enables a separation of the contacting pressure via a pneumatic piston from the sealing pressure applied via metallic screws. The force of the sealing pressure is not applied onto the cell and is thereby limited by the material constraints and not by the mechanical stability of the cell. For accurate voltage measurements, sense wires are separated from the current collection and are electrically isolated from the metallic housing. Thermocouples are used to measure the temperature distribution inside the anodic part of the housing, as close as possible to the cell. The chromium evaporation of the cathode part of the housing is reduced by a protective coating and the utilization of double layered tubes. In the end, the results of preliminary tests are presented.

Diagnostic Yield of Intrathecal Gadolinium MR Myelography for CSF Leak Localization.

Intrathecal gadolinium magnetic resonance (MR) myelography can be used to localize various types of spinal cerebrospinal fluid (CSF) leaks; however, its diagnostic yield is not well known. We sought to determine the diagnostic yield of MR myelography in patients with spontaneous intracranial hypotension. Aretrospective review was performed on all patients who had undergone intrathecal gadolinium MR myelography at our institution from 2002 to 2020 for suspected spinal CSF leak. The MR myelography images were reviewed for the presence or absence of aspinal CSF leak site. Images were also evaluated for the presence an extradural fluid collection. A total of 97patients were included in the final cohort. The average age was 52.6years; 67.0% were female, 4 patients underwent 2 examinations each, yielding atotal of 101 MR myelograms. The source of aspinal CSF leak was localized in 14patients. The diagnostic yield for CSF leak localization on intrathecal gadolinium MR myelography was 14/101 (13.9%) per GdM examination and 14/97 (14.4%) per patient. Among the subset of patients without extradural fluid collections, the yield was 15.7% per examination. All detected leaks were either CSF-venous fistulas or distal nerve root sleeve tears. Intrathecal gadolinium MR myelography is capable of localizing CSF-venous fistulas and distal nerve root sleeve tears; however, our data show that it has alimited diagnostic yield. We suggest that other modalities may be abetter first step before attempting intrathecal gadolinium MR myelography.

Assessment of Marine Coastal Water Pollution from Karachi Harbour Pakistan

: In Pakistan, marine pollution is a major problem that is caused by the waste from industrial, municipal,agronomy, and oil leak sources. The pollutant loads along with the coastline areas near Karachi is received fromterrestrial contaminants including discharges from Karachi Harbour located on the estuary of the Lyari river. Karachigenerates 472 Million Gallon per Day (MGD) of wastewater out of which only 55 MGD is treated and the rest isdischarged in the sea. The prevailing sewage treatment plants are functioning at reduced capacity due to the insufficienttransmission capacity of interceptors. Water sampling was carried out from the Lyari River and five different selectedcoastal point around Karachi harbour for physicochemical parameters and selected heavy metals. Results show that theKarachi Harbour area is noticeably polluted, whereas; the coastal environment in the vicinity of Karachi is also underthe stress of pollution. High COD and BOD5 values were noticed at the Lyari river samples and the sampling locationsclose to the Lyari river outfall area. The Pb, Cd, Ni, and Hg heavy metals that pollute marine water are found. Thissituation is due to the discharge of mixed effluents of industrial and domestic wastes as well as dredging, cargohandling, dumping of ship waste and other coastal activities. The highest value of pollution observed at KarachiHarbour which is near Lyari river mouth, where the domestic and industrial effluents with organic and inorganic wasteshave a greater influence on the water quality and the marine environment. At present, there is no effective controllingmechanism for industries to treat their waste, nor has any investigation to assess increasing marine pollution beencarried out. As a result, there is an adverse impact on fish habitat and mangroves, corrosion of cargo ships, navalvessels and the residents living in the coastal area. Therefore, the government agencies and industrial sectors shouldwork together to avert marine pollution and attain total environmental sustainability.

Prevention of information leakage through channels of spurious electromagnetic radiation and interference: research models

Problem statement. The investigation the currently used methods for determining the sources of information leakage threats from the basic hardware and systems (BHaS) through the spurious electromagnetic radiation and interference (SERaB) channels on the object of informatization (OoI), gives grounds to assert that they have a number of disadvantages. The lack of а formal interpretation for process dynamics of the SERaB information collecting and implementing measures to prevent information leakage requires development of a systematic approach to improving the ways and means of protecting confidential information from leakage through SERaB channels.The purpose. Development of mathematical models and a systematic approach to improving methods and means of protecting confidential information from leaks through the SERaB channels from the BHaS on the OoI.Results. The article substantiates the need for a systematic approach to improving the methods and means of protecting confidential information from leakage through the SERaB channels from the BHaS on the OoI. The authors determined the ways of ensuring the adequacy of the methodological apparatus for the study of these technologies in order to justify measures to prevent leakage. They formulate requirements for techniques used to evaluate the characteristics of measures to prevent information leakage through the SERaB channels. There are describe the procedure of forming the mathematical models set structure for evaluating such characteristics. Also in the article are present the analytical models of the time characteristics of threats to intercept informative SERaB signals on the OoI and measures to prevent information leakage. Finally, the authors are justify the probabilistic format of the indicator of the effectiveness of such measures.Practical relevance. The developed mathematical models can be an effective tool for evaluating the characteristics of measures to prevent information leakage through the SERaB channels.

Dispersion characteristics of hydrogen leakage: Comparing the prediction model with the experiment

A quick and accurate assessment of the hydrogen dispersion when leakage accident happens is useful for minimizing the safety risk. A simplified prediction model was proposed in this paper to predict the dispersion of hydrogen, which was validated by a series of experiments of helium (instead of hydrogen) dispersion in an environmental cabin. The impacts of the helium flow rate, air temperature, and humidity are also explored in the experiments. Results show that when helium leaks continuously upwards in an unobstructed space for a short time, a stable field of concentration will quickly form around the leakage source. The prediction model is found to accurately predict concentration at the central axis when the dimensionless height is 95 < z/d < 195. In addition, A new experimentally fitted entrainment coefficient improve the accuracy of this model, the prediction model is more accurate in predicting the concentration at the central axis. When the jet is dominated by buoyancy and momentum (10 < Fr < 268), buoyancy-dominated (Fr ≤ 10) and momentum-dominated (Fr ≥ 268), the maximum deviations between the prediction model and the experiment are 0.95%, 2.61% and 2.71%, respectively. The deviation of the non-central axis prediction model increase compared with the center line, and the maximum deviation is 17.61%. The distance to the source of leakage and the amount of leakage can be predicted through the rapid prediction model calculation of hydrogen concentration monitoring in the industry.

Study of methane migration in the shallow subsurface from a gas pipe leak

With the increased use of natural gas, safety and environmental concerns from underground leaking natural gas pipelines are becoming more widespread. What is not well understood in leakage incidents is how the soil conditions affect gas migration behavior, making it difficult to estimate the gas distribution. To shed light on these concerns, an increased understanding of subsurface methane migration after gas release is required to support efficient leak response and effective use of available technologies. In this study, three field-scale experiments were performed at the Methane Emission Technology Evaluation Center in Colorado State University to investigate the effect of soil textural heterogeneity, soil moisture, and leak rate (0.5 and 0.85 kg/h) on methane migration caused by leaking pipelines. Subsurface methane concentrations, in addition to soil moisture and meteorological data, were collected over time. A previously validated numerical model was modified and used to understand the observed methane distribution behavior. Results of this study illustrate that the influence of soil texture, leak rate, and moisture on subsurface methane distribution is determined by the relative contribution of advection and diffusion and closely related to the distance to the leak source. Advection dominates gas transport within 1–1.5 m of the leak source, driving the migration of high concentration contours. Beyond this distance, diffusion dominates migration of lower concentration contours to the far-field. Although large leak rates initially result in faster and further gas migration, the leak rate has little influence on the diffusion dominated migration farther from the leak source. Soil moisture and texture complicate gas behavior with texture variations and elevated soil moisture conditions playing a dominant role in locally increasing methane concentrations. Scenarios highlight the importance of understanding the effects of soil moisture, texture, and leak rate on gas migration behavior in an attempt to unravel their contribution to the gas concentration within the soil environment.

Continuous Leak Location in Gas-Filled Steel Pipe Based on Optimum Wavelet Analysis of Leak AE Signal

Abstract This study is investigates how to reconstruct the continuous leak acoustic emission (AE) signal to precisely locate the leak source on a gas-filled steel pipe based on cross-correlation location theory. Thus, in this article, the determination method for the optimum mother wavelet was proposed. The frequency distribution of the continuous leak AE event was firstly extracted through wavelet transform (WT) with optimum mother wavelet. In the considered frequency range, the WT coefficients were further used to reconstruct the raw continuous leak AE signal. The correlation-based location experiments were finally carried out to evaluate the performance of the proposed method. The results show that the location errors of the leak source were decreased by some 10 % compared with those achieved by only using the raw AE signals. Thus, improvement verifies the validity of choice of the optimum mother wavelet. Meanwhile, it is also founded that, whether the reconstructed signals or raw signals were used, the localization accuracy of the leak source using the speed of the T wave is greater than that using the speed of the L wave and theoretical acoustic speed under the same symmetry of the AE sensors with reference to the leak source. Therefore, defining the acoustic speed with the speed of the T wave was recommended to use on-site for detection of the continuous leak source on a gas-filled steel pipe.

Deviation from Clinical Routines Can Reveal Sources of Device Design Vulnerability

The ability to adequately ventilate a patient is critical and sometimes a challenge in the emergency, intensive care, and anesthesiology settings. Commonly, initial ventilation is achieved through the use of a face mask in conjunction with a bag that is manually squeezed by the clinician to generate positive pressure and flow of air or oxygen through the patient's airway. Large or small erroneous openings in the breathing circuit can lead to leaks that compromise ventilation ability. Standard procedure in anesthesiology is to check the circuit apparatus and oxygen delivery system prior to every case. Because the face mask itself is not a piece of equipment that is associated with a source of leak, some common anesthesia machine designs are constructed such that the circuit is tested without the mask component. We present an example of a leak that resulted from complete failure of the face mask due to a tiny tear in its cuff by the patient's sharp teeth edges. This subsequently prevented formation of a seal between the face mask and the patient's face and rendered the device incapable of generating the positive pressure it is designed to deliver. This instance depicts the broader lesson that deviation from clinical routines can reveal unappreciated sources of vulnerability in device design.

Deviation from Clinical Routines Can Reveal Sources of Device Design Vulnerability.

The ability to adequately ventilate a patient is critical and sometimes a challenge in the emergency, intensive care, and anesthesiology settings. Commonly, initial ventilation is achieved through the use of a face mask in conjunction with a bag that is manually squeezed by the clinician to generate positive pressure and flow of air or oxygen through the patient's airway. Large or small erroneous openings in the breathing circuit can lead to leaks that compromise ventilation ability. Standard procedure in anesthesiology is to check the circuit apparatus and oxygen delivery system prior to every case. Because the face mask itself is not a piece of equipment that is associated with a source of leak, some common anesthesia machine designs are constructed such that the circuit is tested without the mask component. We present an example of a leak that resulted from complete failure of the face mask due to a tiny tear in its cuff by the patient's sharp teeth edges. This subsequently prevented formation of a seal between the face mask and the patient's face and rendered the device incapable of generating the positive pressure it is designed to deliver. This instance depicts the broader lesson that deviation from clinical routines can reveal unappreciated sources of vulnerability in device design.

Power side-channel leakage assessment and locating the exact sources of leakage at the early stages of ASIC design process

Power side-channel leakage assessment and locating the exact sources of leakage at the early stages of ASIC design process

DETERMINANTS OF INDONESIA’S RESIDENCE TRAVELING ABROAD

The study aims to identify the economic variables affecting Indonesia’s residence to travel abroad. Knowledge of the variables of Indonesia’s residence to travel abroad is very important because this is one of the sources of foreign exchange leakage. The ARDL approach will be used with time series data for the period 1992-2019. The impact of changes in income, relative prices for Malaysian tourism, and flight availability will be estimated and tested. Two dummy variables are also provided to represent the economic crisis in 1997-1998 and the global financial crisis in 2008. One of the important findings of this study is the significance of the income variable with more than one elasticity, which shows the luxury nature of tourism travel. The relative price of tourism also affects Indonesians to travel abroad in the long- and short-run. The economic crisis of 1997-1998 led to a decrease in Indonesians traveling abroad.

Impact analysis of multi-sensor layout on the source term estimation of hazardous gas leakage

In chemical industry, sensors are used to monitor the leakage and emission of hazardous materials that are used for hazard warning and risk assessment to ensure safety production. The traditional sensor layout designs the scheme at single-layer, and thus causes large deviations in the estimated height and accuracy of source term estimation (STE). In this study, a dual-layer layout scheme for sensors is proposed. The numerical experiments verify that the improved schemes with an equal number of sensors, as well as detection errors, are beneficial to the accuracy of the STE results. The influence of the heights of the sensors and leak source on the results of STE is studied. Results show that the dual-layer sensor scheme with adjacent intervals at high places in the potential search space is highly favorable to locate the leak, and the scheme arranged near the ground is conducive for improving the estimation accuracy of source intensity. This study also compares the STE results of computational fluid dynamics (CFD) simulated scenarios under different sensor schemes and verifies the effectiveness of the proposed dual-layer sensor deployment scheme with adjacent intervals under turbulence condition.

Electrostatic footpads enable agile insect-scale soft robots with trajectory control.

Agility and trajectory control are two desirable features for robotics, but they become very challenging for soft robots without rigid structures to support rapid manipulations. Here, a curved piezoelectric thin film driven at its structural resonant frequency is used as the main body of an insect-scale soft robot for its fast translational movements, and two electrostatic footpads are used for its swift rotational motions. These two schemes are simultaneously executed during operations through a simple two-wire connection arrangement. A high relative centripetal acceleration of 28 body length per square second compared with existing robots is realized on a 65-milligram tethered prototype, which is better than those of common insects, including the cockroach. The trajectory manipulation demonstration is accomplished by navigating the robot to pass through a 120-centimeter-long track in a maze within 5.6 seconds. One potential application is presented by carrying a 180-milligram on-board sensor to record a gas concentration route map and to identify the location of the leakage source. The radically simplified analog motion adjustment technique enables the scale-up construction of a 240-milligram untethered robot. Equipped with a payload of 1660 milligrams to include the control circuit, a battery, and photoresistors, the untethered prototype can follow a designated, 27.9-centimeter-long "S"-shaped path in 36.9 seconds. These results validate key performance attributes in achieving both high mobility and agility to emulate living agile insects for the advancements of soft robots.