Multiple Leakage Research Articles

Fast estimation of dense gas dispersion from multiple continuous CO2 surface leakage sources for risk assessment

Surface leakage of CO2, and associated potential impacts on health, safety, and the environment (HSE) are considered hazards of geologic carbon sequestration (GCS). There are two challenges associated with impact assessment of CO2 surface dispersion. First, the fact that CO2 is a dense gas makes its dispersion in air a complex process. Rigorous numerical solutions for modeling concentration distributions are relatively time-consuming. Second, impact assessment requires consideration of uncertainty, e.g., quantification of how much uncertainty is propagated through input parameters to model outputs by carrying out large numbers of model runs. In order to assess the potential consequences of surface leakage of CO2, it is useful to have a model that executes very quickly for repeated model calculations (e.g., in Monte Carlo mode) of the atmospheric dispersion of CO2 (concentrations as a function of space and time). In addition, the model should be able to handle multiple surface leakage sources. In this study, we have extended the nomograph approach of Britter and McQuaid (1988) for estimating dense gas plume length from single leakage source to multiple leakage sources. The method is very fast and therefore amenable to general system-level GCS risk assessment including uncertainty quantification within the framework of the National Risk Assessment Partnership (NRAP) Integrated Assessment Model (IAM). The method is conservative in that it assumes the wind could be from any direction, and it handles multiple sources by a simple superposition approach. The method produces results in reasonable agreement with a sophisticated computational fluid dynamics (CFD) code, but runs in a small fraction of the time.

Optimization of injection location based on simulations of CO2 leakage through multiple leakage pathways

AbstractAn optimization methodology is proposed to determine an appropriate injection location among potential candidates. The method identifies the optimal injection location by minimizing the total CO2 leakage from all leakage pathways present at a given site. The case of a single injection well and a single leakage pathway is used to quantify the relationships between CO2 leakage rate and major factors. A mathematical model is numerically solved and used to establish a correlation for each factor. The results are extended to the situation of a single injection well and multiple leakage pathways. An explicit expression correlating the asymptotic CO2 leakage rate to the major factors is proposed. Four case studies are illustrated. The results show that the optimal injection location is different in each case and is significantly influenced by the three factors. The proposed approach provides a quantitative tool for minimizing CO2 leakage risk at sites with multiple leakage pathways. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

Electrical characterization of multiple leakage current paths in HfO2/Al2O3-based nanolaminates

The generation of multiple leakage current paths in metal–insulator–semiconductor (MIS) structures with a HfO2/Al2O3-based nanolaminate grown by the ALD technique as insulator material was investigated. The devices were stressed at selected constant voltages in order to achieve accurate values for the occurrence time of every single breakdown event in a time range spanning around 120s. The final result of the degradation experiment is a current-time characteristic with well-defined current steps. It is shown that using an equivalent circuit model formed by an array of series and parallel resistances we are capable of replicating the current increase exhibited by the investigated structures. Taking into account the obtained results for the discrete failure events, the model is extrapolated to the quasi-continuous breakdown case, which provides an even simpler relationship for the leakage current evolution. In this connection, an approximate expression for the time required to reach a given current level is proposed.

A Defect Evaluation Methodology Based on Multiple Magnetic Flux Leakage (MFL) Testing Signal Eigenvalues

This article is based on the associated linearity of magnetic flux leakage signal eigenvalues and detection status information, proposing a methodology that applies multiple magnetic flux leakage signal eigenvalues to evaluate defects and goes a step further in conforming the limitation of the traditional evaluation system, which merely uses signal peak values. In response to the situation that magnetic flux leakage testing signal peak values have been applied as the main parameters to evaluate defects and carry out various related research, we find that the single magnetic flux leakage testing signal peak values cannot exactly represent the leakage magnetic field and reflect the information of the defects. So we attempt to come up with a new way of defects evaluation to better and more accurately evaluate defects. By means of simulation analysis in simulation software ANSYS and experimental verification, the linear relationships between multiple magnetic flux leakage signal eigenvalues and defect parameters through which we can exactly evaluate the defects are obtained, respectively. Finally, the validity of this evaluation system is firmly demonstrated by a practical defect.

Breakdown time statistics of successive failure events in constant voltage-stressed Al2O3/HfO2 nanolaminates

The breakdown time statistics of successive failure events in constant voltage-stressed Al2O3/HfO2 nanolaminates grown by atomic layer deposition (ALD) is investigated. The oxide stack was deposited on a p-type Si substrate and Al was used as the top metal electrode. It is shown that the devices exhibit stepwise current–time characteristics which indicate the formation of multiple leakage current paths spanning the insulating film. It is demonstrated that the arrival rate of the breakdown events can be modeled as a combination of two power-law intensity functions within the framework of a nonhomogeneous Poisson process (NHPP). The change of trend observed during degradation is ascribed to the increasing role played by the series resistance effect in the voltage drop across the nanolaminate. A simple algorithm for calculating the arrival rate of the failure events based on a thinning method is discussed.

Successive application of the layer-related CFP method for internal multiple removal

Internal multiples are very difficult to remove due to their complex raypaths and poor velocity discrimination with primaries. The layer-related common focus point (CFP) method has proven to be effective for internal multiple removal, however, single application leads to multiple leakage when there are several strong reflecting boundaries in the subsurface. In order to reduce this leakage, we propose successive application of the layer-related CFP method for internal multiple removal through cascaded processing of several time levels. In this paper, we concisely reformulate the theory of the boundary- and layer-related CFP methods and compare their robustness to velocity errors. For the layer-related version in particular, we illustrate the specific steps of the method using synthetic data examples. Finally, the successive layer-related CFP method is tested on Mississippi Canyon field data.

Multiple Leakage Detection and Localization Method Based on Bayesian Theory and Genetic Algorithm

To detect and locate the leakage of the pipe correctly, genetic algorithm is combined with Bayesian theory to determine the leaked pipes. Leakage detection and leakage location are carried out separately. Leakage detection is conducted based on the assumption that there is only one leaked pipe, and the simulation result demonstrates its feasibility. When the leakage detection demonstrates there is leaked pipe in the water distribution system, leakage location starts. Based on the information gathered by the manometers, leakage probability in different combinations of the virtual nodal demand can be fixed according to calculating the pressure of the monitored node, then GA is applied to search the maximum Bayesian value, the pipes with maximum Bayesian leakage possibility are believed to be leaked pipes. Optimization programme was made with combination of Matlab and Epanet, numerical simulation results demonstrate the feasibility and effectiveness of the proposed method.

피싱 및 파밍 공격에 의한 다수의 패스워드 유출 요인에 관한 연구

피싱 및 파밍 공격에 의한 다수의 패스워드 유출 요인에 관한 연구

Expression of background potassium channels in rat DRG is cell-specific and down-regulated in a neuropathic pain model

Neuropathic pain is associated with hyperexcitability of DRG neurons. Despite the importance of leakage potassium channels for neuronal excitability, little is known about their cell-specific expression in DRGs and possible modulation in neuropathic pain. Multiple leakage channels are expressed in DRG neurons, including TASK1, TASK3, TRESK, TRAAK, TWIK1, TREK1 and TREK2 but little is known about their distribution among different cell types. Our immunohistochemical studies show robust TWIK1 expression in large and medium size neurons, without overlap with TRPV1 or IB4 staining. TASK1 and TASK3, on the contrary, are selectively expressed in small cells; TASK1 expression closely overlaps TRPV1-positive cells, while TASK3 is expressed in TRPV1- and IB4-negative cells. We also studied mRNA expression of these channels in L4-L5 DRGs in control conditions and up to 4 weeks after spared nerve injury lesion. We found that TWIK1 expression is much higher than TASK1 and TASK3 and is strongly decreased 1, 2 and 4 weeks after neuropathic injury. TASK3 expression, on the other hand, decreases 1 week after surgery but reverts to baseline by 2weeks; TASK1 shows no significant change at any time point. These data suggest an involvement of TWIK1 in the maintenance of the pain condition.

Comparing three feedback internal multiple elimination methods

Abstract Multiple reflections have posed a great challenge for current seismic imaging and inversion methods. Compared to surface multiples, internal multiples are more difficult to remove due to poorer move-out discrimination with primaries and we are left with wave equation-based prediction and subtraction methods. In this paper, we focus on the comparison of three data-driven internal multiple elimination (IME) methods based on the feedback model, where two are well established prediction-and-subtraction methods using back-propagated data and surface data, referred to as CFP-based method and surface-based method, respectively, and the third one, an inversion-based method, has been recently extended from estimation of primaries by sparse inversion (EPSI). All these three methods are based on the separation of events from above and below a certain level, after which internal multiples are predicted by convolutions and correlations. We begin with theory review of layer-related feedback IME methods, where implementation steps for each method are discussed, and involved event separation are further analyzed. Then, recursive application of the three IME methods is demonstrated on synthetic data and field data. It shows that the two well established prediction-and-subtraction methods provide similar primary estimation results, with most of the internal multiples being removed while multiple leakage and primary distortion have been observed where primaries and internal multiples interfere. In contrast, generalized EPSI provides reduced multiple leakage and better primary restoration which is of great value for current seismic amplitude-preserved processing. As a main conclusion, with adaptive subtraction avoided, the inversion-based method is more effective than the prediction-and-subtraction methods for internal multiple elimination when primaries and internal multiples overlap. However, the inversion-based method is quite computationally intensive, and more researches on efficient implementation need to be done in future.

Multiple paravalvular leak 17 years after a second mitral valve replacement

Paravalvular leak (PVL) after prosthetic valve implantation is a significant complication and it usually occurs early in the postoperative period. We report a case of multiple PVL 17 years after the second mitral valve replacement without evidence of infection. The valve sutures were neither cut nor loosened. None of the sewing cuff of the mitral valve was covered with fibrous tissue. The sewing cuff was floated over the native annulus and large and multiple leakage was developed. The valve was easily removed and replaced with a new mechanical prosthesis.

Central Serous Chorioretinopathy With Multiple Leakage Points in a Young Female Patient Without Detected Risk Factors

Central Serous Chorioretinopathy (CSR) is characterized by the accumulation of subretinal fluid at the posterior pole of the fundus, causing serous detachment of the neurosensory retina and / or retinal pigment epithelium. CSR typically affects young and middle-aged men between 20 and 40 years old with type-A personality and is associated with emotional stress. A 21-year-old non-pregnant female presented with a 2-day history of acute, sudden, painless loss of vision and metamorphopsia at the right eye. She complainted also for a central scotoma. On examination of the right eye, the best-corrected visual acuity (BCVA) was 3 / 10. Dilated fundus examination revealed a neurosensory serous detachment and the diagnosis of CSR was confirmed by fluorescein angiography and optical coherence tomography (OCT). Interestingly, the fluorescein angiography revealed multiple leakage points of the dye related to retinal pigmented epithelium defects, while OCT demonstrated a significantly increased retinal thickness. The most astonishing feature of this case report is that it concerns a female patient with acute CSR without any detected risk factors that was characterized by significantly high retinal thickness in OCT in parallel with multiple leakages in fluorescein angiography. As a result, CSR should be taken into account in the differential diagnosis of sudden, painless loss of vision, although the patient may be female without risk factors. doi:10.4021/jmc580w

Central Serous Chorioretinopathy With Multiple Leakage Points in a Young Female Patient Without Detected Risk Factors

Central Serous Chorioretinopathy (CSR) is characterized by the accumulation of subretinal fluid at the posterior pole of the fundus, causing serous detachment of the neurosensory retina and/or retinal pigment epithelium. CSR typically affects young and middle-aged men between 20 and 40 years old with type-A personality and is associated with emotional stress. A 21-year-old non-pregnant female presented with a 2-day history of acute, sudden, painless loss of vision and metamorphopsia at the right eye. She complainted also for a central scotoma. On examination of the right eye, the best-corrected visual acuity (BCVA) was 3/10. Dilated fundus examination revealed a neurosensory serous detachment and the diagnosis of CSR was confirmed by fluorescein angiography and optical coherence tomography (OCT). Interestingly, the fluorescein angiography revealed multiple leakage points of the dye related to retinal pigmented epithelium defects, while OCT demonstrated a significantly increased retinal thickness. The most astonishing feature of this case report is that it concerns a female patient with acute CSR without any detected risk factors that was characterized by significantly high retinal thickness in OCT in parallel with multiple leakages in fluorescein angiography. As a result, CSR should be taken into account in the differential diagnosis of sudden, painless loss of vision, although the patient may be female without risk factors. J Med Cases. 2012;3(3):201-203 doi: https://doi.org/10.4021/jmc580w

Bilateral choroidopathy in systemic lupus erythematosus

We report a case of bilateral choroidopathy in a 35-year-old woman with systemic lupus erythematosus (SLE) diagnosed 3 years previously, and treated with hydroxychloroquine and steroids that ceased 6 months before ocular signs. She complained about rapid bilateral blurred vision with a severe loss of visual acuity. Fluorescein angiography found multiple leakage points in the posterior pole of the pigment epithelium. Ocular coherence tomography (OCT) and fundoscopy showed bilateral retinal detachments. Lupus choroidopathy was diagnosed and high steroids were given intravenously and allowed a rapid improvement. Visual acuity, fundoscopy, retinal angiography and OCT were normalized at 2 months. Choroidopathy is rarely reported in lupus and only about 30 patients are found in the literature.

LOW-LEAKAGE FLIP-FLOPS BASED ON DUAL-THRESHOLD AND MULTIPLE LEAKAGE REDUCTION TECHNIQUES

The scaling of transistor sizes has resulted in dramatic increase of leakage currents. The sub-threshold and gate leakages have now become a major contributor to total power dissipations. This paper presents two flip-flops based on dual-threshold CMOS and multiple leakage reduction techniques to reduce their leakage dissipations. In the DT-TG FF (Dual-Threshold Transmission Gate Flip-Flop), some transistors on non-critical paths use high-threshold devices to reduce their leakage currents, while the other transistors on critical paths use low-threshold devices to maintain performance. The MLRT FF (Multiple Leakage Reduction Technique Flip-Flop) uses P-type CMOS techniques, MTCMOS (Multi-Threshold CMOS) power-gating and dual-threshold technique to reduce both sub-threshold and gate leakage dissipations. Taken as an example, a practical sequential system realized with the two low-leakage flip-flops is demonstrated using a mode-5 × 5 × 5 counter. The simulation results show that the two flip-flops achieve considerable leakage reductions.

The Random Telegraph Signal Behavior of Intermittently Stuck Bits in SDRAMs

This paper reports behavior analogous to the Random Telegraph Signal (RTS) seen in the leakage currents from radiation induced hot pixels in Charge Coupled Devices (CCDs), but in the context of stuck bits in Synchronous Dynamic Random Access Memories (SDRAMs). Our analysis suggests that pseudo-random sticking and unsticking of the SDRAM bits is due to thermally induced fluctuations in leakage current through displacement damage complexes in depletion regions that were created by high-energy neutron and proton interactions. It is shown that the number of observed stuck bits increases exponentially with temperature, due to the general increase in the leakage currents through the damage centers with temperature. Nevertheless, some stuck bits are seen to pseudo-randomly stick and unstick in the context of a continuously rising trend of temperature, thus demonstrating that their damage centers can exist in multiple widely spaced, discrete levels of leakage current, which is highly consistent with RTS. This implies that these intermittently stuck bits (ISBs) are a displacement damage phenomenon and are unrelated to microdose issues, which is confirmed by the observation that they also occur in unbiased irradiation. Finally, we note that observed variations in the periodicity of the sticking and unsticking behavior on several timescales is most readily explained by multiple leakage current pathways through displacement damage complexes spontaneously and independently opening and closing under the influence of thermal vibrations.

Spectral domain optical coherence tomography and angiographic findings in central serous chorioretinopathy complicated by bilateral nonrhegmatogenous retinal detachment associated with systemic corticosteroids

Purpose: To report spectral domail optical coherence tomography (OCT) and angiographic findings in exudative retinal detachment complicating central serous chorioretinopathy.Design: interventional case report.Methods: 33-year old man with bilateral nonrhegmatogenous retinal detachment, misdiagnosed as uveitis, iatrogenically treated with systemic corticosteroids.Results: Discontinuation of corticotherapy led to anatomic and visual improvement. Fluorescein angiography demonstrated multiple leakage points; indocyanine green angiography disclosed large hyperfluorescent patches in the choroid and OCT demonstrated retinal detachment with dense subretinal deposits.Conclusion: The recognition of this atypical presentation with a combination of opthalmoscopic, angiographic and OCT findings may avoid inappropriate diagnosis and treatment with corticosteroids.

Chronic Central Serous Chorioretinopathy Associated with Serous Retinal Detachment in a Series of Asian Patients

Purpose: To determine clinical features of patients with severe chronic central serous chorioretinopathy (diffuse retinal pigment epitheliopathy, DRPE) associated with bullous retinal detachment in Thailand. Methods: The authors reviewed clinical and imaging characteristics, visual outcomes, and complications of 7 patients with severe DRPE associated with bullous retinal detachment. Results: Included were 6 males and 1 female with average age at onset of 39 years (range 30–46 years) diagnosed with DRPE. Although 4 patients had unilateral complaints, retinal pigment epithelium (RPE) changes on fluorescein angiography (FA) were visible in both eyes in all patients and 10 out of 14 affected eyes exhibited large exudative bullous retinal detachments (RD) and evidence of multiple characteristic leakage points. The disease was induced by steroid medications in 3 patients and an additional 3 patients received steroid treatment after they were initially considered to have Harada disease. The administration of steroids caused worsening in all cases. Conclusion: Chronic central serous chorioretinopathy associated with bullous retinal detachment is a severe variant of DRPE, which might be mistaken for Harada disease. The early diagnosis of DRPE might prevent the complications from harmful medications as well as unnecessary surgery and visual loss.

A Case of Vogt-Koyanagi-Harada Disease in a Patient With Graves Disease

A case of Vogt-Koyanagi-Harada disease (VKH) that developed in a 36-year-old woman with Graves' disease was described. The patient was treated with Lugol's solution and presented with bilateral serous retinal detachment. She had also suffered from methimazole-induced hypersensitivity and steroid-induced myopathy. Fluorescein angiography showed multiple leakage points and a lumbar puncture revealed pleocytosis, which was compatible with VKH. High dose steroid pulse therapy was successful. Altered immune regulation associated with drug-induced hypersensitivity may contribute to the development of VKH in patients with Graves' disease.

A 90-nm Power Optimization Methodology With Application to the ARM 1136JF-S Microprocessor

An electrical and physical design power optimization methodology and design techniques developed to create an IC with an ARM 1136JF-S microprocessor in 90-nm standard CMOS are presented. Design technology and methodology enhancements to enable multiple supply voltage operation, leakage current and clock rate optimization, single-pass RTL synthesis, VDD selection, power optimization and timing and electrical closure in a multi-VDD domain design are described. A 40% reduction in dynamic and a 46% reduction in leakage power dissipation has been achieved while maintaining a 355-MHz operating clock rate under typical conditions. Functional and electrical design requirements were achieved with the first silicon