Flow Tracing Research Articles

A Study on Quantitative Methodology to Assess Cyber Security Risk of SCADA Systems

This paper aims to identify and clarify the cyber security risks and their interaction with the power system in Smart Grid. The SCADA system and other communication networks interact with the power system on a real time basis, so it is important to understand the interaction between two layers to protect the power system from potential cyber threats. In this study, the optimal power flow (OPF) and Power Flow Tracing are used to assess the interaction between the SCADA network and the power system. Through OPF and Power Flow Tracing based analysis, the physical and economic impacts from potential cyber threats are assessed, and thereby the quantitative risks are measured in a monetary unit.

Automated aortic Doppler flow tracing for reproducible research and clinical measurements.

In clinical practice, echocardiographers are often unkeen to make the significant time investment to make additional multiple measurements of Doppler velocity. Main hurdle to obtaining multiple measurements is the time required to manually trace a series of Doppler traces. To make it easier to analyze more beats, we present the description of an application system for automated aortic Doppler envelope quantification, compatible with a range of hardware platforms. It analyses long Doppler strips, spanning many heartbeats, and does not require electrocardiogram to separate individual beats. We tested its measurement of velocity-time-integral and peak-velocity against the reference standard defined as the average of three experts who each made three separate measurements. The automated measurements of velocity-time-integral showed strong correspondence (R(2) = 0.94) and good Bland-Altman agreement (SD = 1.39 cm) with the reference consensus expert values, and indeed performed as well as the individual experts ( R(2) = 0.90 to 0.96, SD = 1.05 to 1.53 cm). The same performance was observed for peak-velocities; ( R(2) = 0.98, SD = 3.07 cm/s) and ( R(2) = 0.93 to 0.98, SD = 2.96 to 5.18 cm/s). This automated technology allows > 10 times as many beats to be analyzed compared to the conventional manual approach. This would make clinical and research protocols more precise for the same operator effort.

A Wide-Area Measurement Systems-Based Adaptive Strategy for Controlled Islanding in Bulk Power Systems

Controlled islanding is the last countermeasure for a bulk power system when it suffers from severe cascading contingencies. The objective of controlled islanding is to maintain the stability of each island and to keep the total loss of loads of the whole system to a minimum. This paper presents a novel integrated wide-area measurement systems (WAMS)-based adaptive controlled islanding strategy, which depends on the dynamic post-fault trajectories under different failure modes. We first utilize an improved Laplacian eigenmap algorithm (ILEA) to identify the coherent generators and use the slow coherency grouping algorithm to guarantee coherent stability within an island. Using the identification result, we then define the minimum coherent generator virtual nodes to reduce the searching space in a graph and utilize the k-way partitioning (KWP) algorithm to obtain a preliminary partition of the simplified graph. Based on the preliminary partition, we consider the direction of power flow and propose a variable neighborhood heuristic searching algorithm to search the optimal separation surfaces so that the net imbalanced power of islands is minimized. Finally, the bidirectional power flow tracing algorithm and PQ decomposition power flow analysis are utilized to determine the corrective controls within each island. The test results with the New England 39-bus system and the IEEE 118-bus system show that the proposed integrated controlled islanding strategy can automatically adapt to different fault modes through generator coherency identification and effectively group the different coherent generators into different islands.

Metallurgical analysis of lithium test assembly operated for 1200 h

A lithium test assembly used for lithium-free surface flow experiments at 300°C for 1200h at Osaka University was analyzed metallographically to verify the design of the lithium target of the International Fusion Materials Irradiation Facility (IFMIF). Certain irregularities such as traces of high-speed lithium flow at a maximum velocity of 15m/s were observed at the tip of the nozzle. Mottled unevenness with numerous microcracks a few microns deep was detected at the inlet of the nozzle, the velocity ratio of which was 0.1–0.4 as compared with the nozzle tip. A thin, altered layer developed on the surface of these regions because of carbide formation. It is believed that the microcracks were nucleated by thermal transients at the start or stop of operations of the lithium loop. These slight irregularities could be the result of exfoliation of the altered layer because of the high-speed lithium flow caused by the increased hardness of the altered layer as compared with that of the base metal. The metallurgical analysis proved for the first time that carbon control in lithium is also important for corrosion and erosion protection of the IFMIF components.

Optimal power flow control of power transmission networks using graph algorithms

In this paper optimal power flow control of power transmission networks using graph theory is presented. Graph theory is employed to trace the optimal path of power flow in transmission lines. Graph theory-based search algorithms such as Depth First Search and Breadth First Search are used for determining the sequence of tracing of nodes. Loops in the network are formed such that each loop contains at least one active source. The algorithms are tested on a six bus system using MATLAB programs. Considering the real power losses and the time required for computation of power flow tracing, the graph algorithms give better results compared to the conventional Newton–Raphson method.

Cardiogenic oscillation in pediatric patients after cardiac surgery

Cardiogenic oscillation is the fluctuation in flow tracing in mechanically ventilated patients. Large cardiogenic oscillation may cause autotriggering in adult patients after cardiac surgery [1] and inaccurate volume monitoring [2]. However, it is unknown how cardiogenic oscillation is problematic in pediatric patients. Therefore, we prospectively surveyed cardiogenic oscillation in pediatric patients after cardiac surgery.

Implementation of traceability principle in the production of Zlatar cheese

The traceability elements that must be applied during the traditional process of production and distribution of Zlatar cheese are presented in this paper. The activities that are implemented in order to obtain label of a product with geographical origin necessarily include the mechanism of risk management in the food safety system. Therefore, it is imperative that the basic principles of production of Zlatar cheese involve the provision of a reliable system that allows tracing of the entire production fl ow in order to identify and eliminate the potential risks to consumer health, and thus, indirectly, to protect it. The mechanism shown are in function of the improvement of quality and safety of this traditional product, reduction of the health risk to consumers, which in a direct way contributes to its better competitiveness and opening roads in the local and surrounding markets.

A TCSC Incorporated Power Flow Model for Embedded Transmission Usage and Loss Allocation

Authors present a power flow tracing based method for usage and loss allocation along with FACTS devices. Graph theory is the basis for usage allocation. Modified Kirchhoff matrix is used for this purpose. FACTS devices are used in the system for various purposes such as reactive power compensation; voltage profile improvement etc. hence in this paper Thyristor controlled series controller (TCSC) with voltage source modeling is used for finding the effect of FACTS device on transmission usage and loss allocation. A sample 5 bus is used for this purpose.

Динамический анализ программ с целью поиска ошибок и уязвимостей при помощи целенаправленной генерации входных данных

This paper describes the principles of program dynamic analysis for defect detection using input data generation. Techniques of program transformation allowing execution trace extraction, data flow tracing and input data generation for execution path coverage approaches are considered. We clarify in what way such an approach allows us to perform fully automatic analysis using executable or interpretable code. This paper also presents dynamic analysis tools developed at Institute for System Programming RAS---Avalanche (Valgrind-based tool) and a prototype tool for Java applications. The paper concludes with an evaluation of practical results of applying Avalanche tool to a set of open source projects as well as results of applying Java analysis tool to detect concurrency defects.

A Power Flow Tracing based Method for Transmission Usage, Loss & Reliability Margin Allocation

Restructuring of Electricity supply industry introduced many issues such as transmission pricing, transmission loss allocation and congestion management. Many methodologies and algorithms were proposed for addressing these issues. In this paper a graph theory based method is proposed which involves Matrices methodology for the transmission usage, loss and transmission reliability margin (TRM) allocation for generators and demands. This method provides loss and TRM allocation in a direct way because all the computation is previously done for usage allocation. The proposed method is simple and easy to implement in a large power system. Further it is less computational because it requires matrix inversion only a single time. A comparison between proposed method and already exiting methods also presents. Results are shown for the sample 6 bus system and IEEE 14 bus system.

Automated flow quantification for spin labeling MR imaging

The Time-Spatial Labeling Inversion Pulse (Time-SLIP) technique enables tracing of regional fluid flows without the use of contrast medium. The objective of this study is to quantify automatically slow and complex fluid flows using the Time-SLIP technique. Series images were acquired with a 1.5-T MRI scanner using the Time-SLIP technique with half-Fourier fast spin-echo (FSE) and balanced steady-state free precession (bSSFP) sequences. In this method, labeled fluid regions in images were automatically detected based on image processing techniques for a given point. The flow velocity of the labeled fluid region was calculated using regression fitting for the region's position. To evaluate our method, constant and non-constant laminar flows in a water phantom were studied. In addition, volunteer experiments were conducted to quantify the flow of cerebrospinal fluid. In the constant flow experiments the correlation factor r (2) between the flow velocity calculated from our method and the laminar peak velocity calculated from the volumetric flow rate was 0.9992 for the FSE sequence and 0.9982 for the bSSFP sequence. In the non-constant flow study, the flow velocity was calculated accurately for any period inversion time even when the flow velocity was changed, and the quantification error was negligible. In the volunteer experiments, r (2) between the flow velocity calculated by the proposed method and that obtained by manual annotation was 0.9383. The experimental results showed that our proposed method can quickly and accurately provide information on flow velocities especially for slower and complex flows. Our method is, therefore, expected to be useful in diagnostic support systems.

Measurement of speed of sound in poly(lactic acid)-clay composite

We measured longitudinal speed of sound for matrix[poly(lactic acid)]-additive(clay particles) composite rectangular-solid specimen prepared by injection molding. It was found that the speed of sound measured in the direction along the longer side of the specimen was the highest at the middle of the specimen. This trend corresponded with that for crystallinity determined through differential scanning calorimetry (DSC). A cross section view of the specimen parallel to its longer side showed that there was a transverse flow trace of resin in the vicinity of the injection gate while the flow trace along the direction of the longer side spread wider as getting far from the gate toward the middle of the specimen. The high crystallinity appeared in the middle of the specimen was inferred to come from the promotion of crystallization by molecular orientation induced with the above flow trace parallel to the direction along the longer side of the specimen.

Eddy, a formal language for specifying and analyzing data flow specifications for conflicting privacy requirements

Increasingly, companies use multi-source data to operate new information systems, such as social networking, e-commerce, and location-based services. These systems leverage complex, multi-stakeholder data supply chains in which each stakeholder (e.g., users, developers, companies, and government) must manage privacy and security requirements that cover their practices. US regulator and European regulator expect companies to ensure consistency between their privacy policies and their data practices, including restrictions on what data may be collected, how it may be used, to whom it may be transferred, and for what purposes. To help developers check consistency, we identified a strict subset of commonly found privacy requirements and we developed a methodology to map these requirements from natural language text to a formal language in description logic, called Eddy. Using this language, developers can detect conflicting privacy requirements within a policy and enable the tracing of data flows within these policies. We derived our methodology from an exploratory case study of the Facebook platform policy and an extended case study using privacy policies from Zynga and AOL Advertising. In this paper, we report results from multiple analysts in a literal replication study, which includes a refined methodology and set of heuristics that we used to extract privacy requirements from policy texts. In addition to providing the method, we report results from performing automated conflict detection within the Facebook, Zynga, and AOL privacy specifications, and results from a computer simulation that demonstrates the scalability of our formal language toolset to specifications of reasonable size.

Evaluation of Cardiac Functions and Atrial Electromechanical Delay in Children With Adenotonsillar Hypertrophy

Deterioration of the right ventricular (RV) functions and the increase in the pulmonary arterial pressure (PAP) of children with moderate to severe adenotonsillar hypertrophy (ATH) have been well described. In addition to these complications, this study aimed to investigate the influence of ATH on the conduction system. The study investigated 46 patients with a diagnosis of ATH and 46 healthy control subjects. Conventional echocardiography, P-wave dispersion (Pd), tissue Doppler imaging (TDI) findings, and atrial electromechanical delay (AED) were compared between the patients and the control subjects before and after adenotonsillectomy. The maximum P-wave duration and Pd were significantly higher in the patients than in the control subjects (p < 0.001). The patient group showed significantly greater RV end-diastolic dimension (p = 0.01), right atrial area (p < 0.001), and mean PAP (p = 0.03) but lower E/A ratios for the mitral (p = 0.04) and tricuspid (p = 0.01) valves and a shorter pulmonary flow trace acceleration time (p = 0.03). The tricuspid annular-plane systolic excursion was similar between these groups (p = 0.21). In the patient group, TDI studies showed significantly lower E'/A' ratios for the tricuspid lateral (p = 0.006) and mitral septal (p = 0.003) segments than in the control group. The myocardial performance index was lower for the mitral lateral, mitral septal, and tricuspid lateral segments in patient group (p < 0.001). Similarly, AED was prolonged in the patient group at all three segments (p < 0.001). Also, the patient group showed a significantly longer interatrial (p = 0.03) and intraatrial (p = 0.04) electromechanical delay. However, all the electro- and echocardiographic parameters were similar between the patients and the control subjects after adenotonsillectomy (p > 0.05). The prolongations in P-wave duration, Pd, and inter- and intraatrial electromechanical delays were first shown in this population. The cardiac changes induced by ATH-associated hypoxia may facilitate arrhythmias during the long term.

Elasticity Properties of Pulmonary Artery in Patients with Bicuspid Aortic Valve

Although the vascular complications of bicuspid aortic valve (BAV) disease cause significant morbidity and mortality, the role of pulmonary artery in this pathogenesis is less understood. We aimed to assess the elastic properties of pulmonary artery with echocardiography in patients with BAV. Thirty patients with BAV (26 males) were enrolled in this study. The presence of aortic stenosis was accepted as exclusion criteria. Thirty-two healthy subjects (27 males) with no any history of cardiovascular disease comprised the control group. In all patients, maximal frequency shift (MFS) and acceleration time (AcT) of the pulmonary artery flow trace were measured echocardiographically in parasternal short-axis view. Subsequently, pulmonary artery stiffness (PAS) was calculated by using the following formula PAS (kHz/sec) = MFS/AcT. There were no significant differences in baseline demographic characteristics of the study population. Aortic strain and aortic distensibility index were lower, and aortic stiffness index (SI) higher, in patients with BAV. The PAS was significantly increased in patients with BAV compared with control subjects with tricuspid aortic valve (11.08 ± 2.27 vs. 7.11 ± 1.54, P < 0.001). There was a significant correlation between aortic diameters, aortic elasticity indexes, and PAS. Multivariate linear regression analysis, the only significant independent factor affecting the PAS was SI (β = 0.547, P < 0.001). We demonstrated that elastic properties of pulmonary artery tend to be impaired as in the aorta in patients with BAV disease.

Inversion of a dual-continuum approach to flow in a karstified limestone: Insight into aquifer heterogeneity revealed by well-test interferences

Summary Two large sets of interference testing data from a karstic aquifer (Hydrogeological Experimental Site, HES – Poitiers – France) are inverted using a dual-continuum approach to groundwater flow. The parameterization technique used to infer spatially distributed hydrodynamic parameters is free of any prior estimation regarding the spatial structure of the parameter fields; it merely seeks the minimal number of local values to obtain the best fit between flow simulations and data. A previous work inverting without any prior geostatistical assumption the same set of data based on a single flowing continuum produced nicely structured (spatially correlated) parameter fields. The dual-continuum approach renders fields as patchworks of subareas of quite uniform values. The statistical distribution of the hydrodynamic parameters is generally skewed toward high values, especially when interference data bear traces of rapid channeled flow in karstic conduits. It is now well established that continuous approaches to flow are well suited to simulate diffusive flow in fractured – karstified rocks, although single continuums may result in artificially high contrasts of hydraulic diffusion values between flowing and non-flowing areas. In the case of a dual continuum, the model has in its physics the capability to clearly separate conduction properties attached to fractures and channels from capacitive properties of the host matrix. We show that high contrasts of hydraulic diffusion disappear, resulting in a mildly heterogeneous medium in which high values of hydraulic diffusion are only located in areas where channeled flow occurs.

Performance evaluation of a water resources system under varying climatic conditions: Reliability, Resilience, Vulnerability and beyond

Summary As introduced by Hashimoto et al. (1982), Reliability, Resilience, and Vulnerability (RRV) metrics measure different aspects of a water resources system performance. Together, RRV metrics provide one of the most comprehensive approaches for analyzing the probability of success or failure of a system, the rate of recovery (or rebound) of a system from unsatisfactory states, as well as quantifying the expected consequence of being in unsatisfactory states for extended periods. Assessing these comprehensive metrics at current (baseline) and future scenarios provide insight into system performance in changing or varying climatic conditions. Such an approach makes it possible to analyze different scenarios that could include specific mitigation or adaptation strategies to accommodate a varying climate. The method requires a subjective decision defining what constitutes an “unsatisfactory state” depending on acceptable risks. The application of this methodology is demonstrated using Tampa Bay Water’s Enhanced Surface Water System. In this case, for each scenario, a thousand ensembles of 300-years of monthly stream flow traces were first generated by a multi-site rainfall/runoff model. Second, a novel nonlinear disaggregation algorithm was developed to translate monthly outputs into daily values. The daily stream flow traces and their derivatives are then used to drive complex operational models that produce several system variables (e.g., permitted river withdrawals, reservoir storage volumes, and treatment plant production rates) at different locations. Outputs from the operational model were then used to define criteria over which the RRV and other metrics were evaluated. Several mitigation scenarios such as treatment and reservoir capacity expansion, as well as adaptation through operational changes were considered to evaluate system performance under varying climatic conditions. The approach highlights the benefits of comprehensive system performance metrics that are easy to understand by decision makers and stake holders and demonstrates the implementation of seemingly intractable ensemble size and simulation length in a distributed computing environment.

A Comprehensive Review of Embedded Transmission Pricing Methods Based on Power Flow Tracing Techniques

Restructuring of electricity supply industry introduced the concept of deregulation. After deregulation transmission cost allocation is a vital issue. In the available literature, various authors have presented different methods for allocation of transmission cost. This paper presents the review of a variety of methods and algorithm based on the principle of power-flow tracing. For a fair and equitable transmission charge allocation it is necessary to know the quantum of power flowing by each generator and load in line flows. Power flow tracing techniques are mainly based on the concepts of proportional sharing principle, graph theory, circuit theory (Z-bus tracing), optimization approach, relative electrical distance concept, Equilateral bilateral exchange (EBE), and game theory. This paper presents a comprehensive review of all the available literature on the above.

Carbon Flow Tracing Method for Assessment of Demand Side Carbon Emissions Obligation

As increasing number of nations, industries, and individuals are involved in the carbon mitigation initiative, it becomes significant to answer what amount of carbon emissions social entities are responsible for, especially from electricity service. In this paper, a carbon flow tracing method is presented to determine carbon emissions obligation from electricity consumption. The method traces energy sources of electricity consumption across the electricity network to determine the indirect carbon emissions caused. From a “generation-to-consumption” perspective, the transmission characteristic of electricity supply and locational energy mix are reflected. The method is employed to address two important issues uniformly, i.e., carbon accounting at the regional level and locational carbon intensity assessment at the user level, respectively. Test results from two examples show that the method is a preferable choice to solve the two problems. Additionally, the method may contribute to carbon reduction cooperation and end user participation in carbon mitigation.

Toward an RFID Scheme for Secure Material Flow Tracing and Verification in Supply Chains

Radio Frequency Identification (RFID) is an important wireless communication and pervasive computing technique used for automatic item identification and data capture. In this paper, we present a scheme for securely tracing material flow in supply chains using the inherent RFID authentication and data logging capability. The scheme provides not only an overall path tracing and verification through the entire supply chain, but also the product identification within the scope of a supply chain partner. RFID tags and readers are deployed to ensure that only authorized supply chain partners can identify the tagged items in a secure and private way. The authors develop tag-reader authentication protocols to ensure the authenticity of RFID tags and readers. Their approach avoids the single point failure of the supply chain server – there is no need for each supply chain partner to communicate with the server for every material flow. Therefore, it minimizes the risks caused by system interruptions due to network failures or server unavailability.