Current System Configuration Research Articles

An adaptive stabilizing imposter detection scheme for distributed mobile wireless sensor networks

Mobile wireless sensor networks (MWSNs) are wireless networks of small sensors moving around a certain coverage area relaying information among themselves and conveying their readings and data to base stations. Imposters are malicious nodes actively engaging other legitimate nodes in the network to read or inject wrong data. MWSN are susceptible to imposter attack and therefore, the protection of MWSN from imposter nodes placed by an adversary to contaminate the sensed data is essential for the reliability of its operation. Imposters detection algorithms need to be distributed in nature and therefore they are susceptible to variety of faults that can perturb the variables for algorithm and cause a major malfunction in the operation of the algorithm and subsequently the entire network if proper recovery mechanisms are not employed. The distributed nature of imposter detection schemes for WSN and the physical environment where the sensors are deployed require some approaches such as stabilization to deal with faults. A stabilizing distributed algorithm can withstand transient faults and start in an arbitrary initial configuration by eventually entering a legitimate system configuration regardless of the current system configuration. We view a fault as a transient fault if it affects the states of the system processes but not their program. In this paper, we propose an imposter detection scheme that can effectively deal with transient faults and arbitrary initialization. In addition, the proposed algorithm effectively adapts to the introduction and the removal of sensor nodes to/from the WSN which makes the proposed algorithm appropriate for practical sensor network applications. Other faults that can occur in the network and in the nodes are beyond the scope of this work.

A Colorful Blackout: The Havoc Caused by Auroral Electrojet Generated Magnetic Field Variations in 1989

The Hydro-Quebec system is a winter-peaking system whose all-time record peak load of 39,240 MW was recorded in January 2014. Hydro-Quebec exports to neighboring systems in Canada and the United States, with an annual transaction volume of approximately 30 TWh. The current system configuration is based on the major development projects of the 1960s and 1970s. In 1965, as part of the development of the Manic-Outardes hydroelectric complex, Hydro-Quebec commissioned the world's first 735-kV lines, which had a much greater capacity than the existing 315-kV lines put into service in the late 1950s with the development of the Bersimis hydroelectric complex. In 1971, Hydro-Quebec launched what was then dubbed the project of the century: the development of the La Grande River complex in the James Bay region at the southern end of Hudson Bay. In 1996, when the final generating station, Laforge-2, was commissioned at the end of the second phase of the project, La Grande became the largest hydroelectric facility in the world, a title it retained for a number of years.

Study of extreme ultraviolet lithography patterned mask inspection tool for half-pitch 11-nm node defect detection performance

Extreme ultraviolet lithography (EUVL) patterned mask defect detection is one of the major issues to overcome for realization of EUVL-based device fabrication. We have designed projection electron microscope (PEM) optics that have been integrated into a new inspection system called EBEYE-V30 (“Model EBEYE” is EBARA’s model code), and the PEM system performs well in half-pitch (hp) 16-nm node EUVL patterned mask inspection applications. We also discuss the extendibility of this system to 11-nm node defect detection. The progress made in the performance of the PEM optics is not simply about producing an image sensor with higher resolution but is also about improvement of the image processing to enhance the defect signal. A high-speed image sensor, a high-speed image-processing circuit, and a bright and stable electron source are necessary for hp 11-nm defect inspection. We describe the experimental results for EUVL patterned mask inspection using the above system for the hp 11-nm node. Programmed hp 11-nm defects (equivalent to 44 nm on the mask) are used for defect detection sensitivity evaluation. Defects as small as 16 nm on the mask could be detected using the current PEM system configuration.

Public street lighting service standard assessment and achievement

Nighttime lighting is an important public service that impacts human activities and promotes transportation and pedestrian safety. Of course, such services are not free and have been found to have negative impacts on the environment. Responsible stewardship of the built environment requires that efficiency and care in the delivery of services be taken, particularly in the context of sustainability concerns. A significant problem with existing urban infrastructure systems like street lighting is that they have evolved over time using rule-of-thumb planning standards. Given this, systematic assessment and re-evaluation offers much potential for enhancing the spatial efficiency of infrastructure but also the opportunity to explicitly account for environmental impacts in combination with safety and security. This paper applies a methodology for studying lighting in urban areas based upon the use of spatial analytics, including GIS and spatial optimization. Findings and results are reported for a study area in San Diego, California, highlighting current system configuration issues, method development and the potential long term benefits of systematic analysis of public sector services.

An integrated assessment of water-energy and climate change in sacramento, california: how strong is the nexus?

This paper is among the first to report on the full integration of basin-scale models that include projections of the demand and supply of water and energy for residential, commercial, industrial, and agricultural sector users. We link two widely used regional planning models that allow one to study the impact of rising climate variability on water and electricity use in Sacramento, California. Historic data combined with the current energy and water system configuration was used to assess the implications of changes in temperature and precipitation. Climate simulations suggest that electricity imports to the region would increase during hot dry spells, when regional power production is most constrained. In particular, regional imports of electricity would increase over 35 % in hot dry years, assuming a 4 °C increase in average temperature and a 25 % decrease in average precipitation.

Energy-saving control model of inverter for centrifugal pump systems

The inverter control strategy is the key to pump energy-saving operation and should be established based on the current system configurations and system requirements, which is not the case in practice. As a result, the characteristics of pump system requirements and a combination pump with inverter were studied, and the mathematical models were established. A new model for an optimal inverter control strategy based on the current system configurations and system requirements was then established, and a method combining golden section search and genetic algorithm was formulated to solve this optimal model. This model sets up an optimal inverter control strategy to increase the efficiency of pump operation following a process line near the minimum requirements to improve operation conditions. The implementation difficulty of the control law was also reduced. Finally, the optimized model was applied to an industrial circulating pump system, and the result showed that the model can not only determine the optimal inverter control strategy but also evaluate the current operation situation of the pump configuration and determine the energy-saving potential for the current configuration, which can aid in the subsequent energy-saving reconstruction.

Rationalism with a dose of empiricism: combining goal reasoning and case-based reasoning for self-adaptive software systems

Requirements-driven approaches provide an effective mechanism for self-adaptive systems by reasoning over their runtime requirements models to make adaptation decisions. However, such approaches usually assume that the relations among alternative system configurations, environmental parameters and requirements are clearly understood, which is often not true. Moreover, they do not consider the influence of the current configuration of an executing system on adaptation decisions. In this paper, we propose an improved requirements-driven self-adaptation approach that combines goal reasoning and case-based reasoning. In the approach, past experiences of successful adaptations are retained as adaptation cases, which are described by not only requirements violations and contexts, but also currently deployed system configurations. The approach does not depend on a set of original adaptation cases, but employs goal reasoning to provide adaptation solutions when no similar cases are available. Case-based reasoning is used to provide more precise adaptation decisions that better reflect the complex relations among requirements violations, contexts, and current system configurations by utilizing past experiences. To prevent case-based reasoning from getting trapped in suboptimal adaptation solutions, an additional case mutation mechanism is introduced to mutate existing adaptation solutions when necessary. We conduct an experimental study with an online shopping benchmark to evaluate the effectiveness of our approach. The results show that our approach outperforms both a requirements-driven approach and a case-based approach in terms of satisfaction level of quality constraints. The results also confirm the effectiveness of case mutation for producing better adaptation solutions. In addition, we empirically investigate the evolution process of adaptation solutions. The evolution analysis reveals some general evolution trends of adaptation solutions such as different evolution phases.

A model-driven approach to broaden the detection of software performance antipatterns at runtime

Performance antipatterns document bad design patterns that have negative influence on system performance. In our previous work we formalized such antipatterns as logical predicates that predicate on four views: (i) the static view that captures the software elements (e.g. classes, components) and the static relationships among them; (ii) the dynamic view that represents the interaction (e.g. messages) that occurs between the software entities elements to provide the system functionalities; (iii) the deployment view that describes the hardware elements (e.g. processing nodes) and the mapping of the software entities onto the hardware platform; (iv) the performance view that collects specific performance indices. In this paper we present a lightweight infrastructure that is able to detect performance antipatterns at runtime through monitoring. The proposed approach precalculates such predicates and identifies antipatterns whose static, dynamic and deployment sub-predicates are validated by the current system configuration and brings at runtime the verification of performance sub-predicates. The proposed infrastructure leverages model-driven techniques to generate probes for monitoring the performance sub-predicates and detecting antipatterns at runtime.

Ecologically sustainable but unjust? Negotiating equity and authority in common-pool marine resource management

Under appropriate conditions, community-based fisheries management can support sound resource stewardship, with positive social and environmental outcomes. Evaluating indigenous peoples’ involvement in commercial sea cucumber and geoduck fisheries on the central coast of British Columbia, Canada, we found that the current social-ecological system configuration is relatively ecologically sustainable according to stock assessments. However, the current system also results in perceived inequities in decisionmaking processes, harvesting allocations, and socioeconomic benefits. As a result, local coastal resource managers envision a transformation of sea cucumber and geoduck fisheries governance and management institutions. We assessed the potential robustness of the proposed institutions using Elinor Ostrom’s common-pool resource design principles. Grounded in the region’s legal, political, and historical context, our analysis suggests that greater local involvement in these invertebrate fisheries and their management could provide more benefits to local communities than the status quo while maintaining an ecologically sustainable resource. Our research highlights the importance of explicitly addressing historical context and equity considerations in social-ecological system analyses and when renegotiating the institutions governing common-pool resources.

TLA: Temporal look-ahead processor allocation method for heterogeneous multi-cluster systems

In a heterogeneous multi-cluster (HMC) system, processor allocation is responsible for choosing available processors among clusters for job execution. Traditionally, processor allocation in HMC considers only resource fragmentation or processor heterogeneity, which leads to heuristics such as Best-Fit (BF) and Fastest-First (FF). However, those heuristics only favor certain types of workloads and cannot be changed adaptively. In this paper, a temporal look-ahead (TLA) method is proposed, which uses an allocation simulation process to guide the decision of processor allocation. Thus, the allocation decision is made dynamically according to the current workload and system configurations. We evaluate the performance of TLA by simulations, with different workloads and system configurations, in terms of average turnaround time. Simulation results indicate that, with precise runtime information, TLA outperforms traditional processor allocation methods and has up to an 87% performance improvement.

Power conversion systems for modern ac–dc power systems

SUMMARYThis paper discusses the present and future power conversion systems for high voltage direct current transmission systems. It begins with an introduction into the commercially available semiconductor switching devices and future wide bandgap devices specifically silicon carbide devices. Different High Voltage Direct Current (HVDC) system configurations including the point‐to‐point, back‐to‐back, multi‐terminal, and hybrid ac and dc are discussed. Different configurations of the current source and voltage source converters are presented, and the concept of redundancy and availability for the current source and voltage source schemes is elaborated on. The most significant trends in dc power systems including the transformerless HVDC, ultra high voltage dc transmission, ac to dc replacement, tripole HVDC, dc grids, dc circuit breakers, and dc transformers are presented. Copyright © 2011 John Wiley & Sons, Ltd.

Testing resilience thinking in a poverty context: Experience from the Niger River basin

Resilience thinking is an important addition to the range of frameworks and approaches that can be used to understand and manage complex social–ecological systems like small-scale fisheries. However, it is yet to lead to better environmental or development outcomes for fisheries stakeholders in terms of food security, improved livelihoods and ecological sustainability. This paper takes an empirical approach by focusing on the fundamentals of resilience thinking to evaluate its usefulness in developing relevant management interventions in small-scale fisheries in the Niger River Basin in West Africa. The paper presents the outputs of a participatory assessment exercise where both fishery communities and local experts were involved at two different scales. The resilience frame used was designed to facilitate the identification of socially defined thresholds that help delineate the desirability of the current system configuration and provides a diagnosis framework that tailors management solutions to problems in local context. The analysis highlights some key contributions from resilience thinking to the challenge of diagnosis in small-scale fisheries management in developing countries, as well as important contributions that emerge from taking a pragmatic and critical approach to its application.

False data injection attacks against state estimation in electric power grids

A power grid is a complex system connecting electric power generators to consumers through power transmission and distribution networks across a large geographical area. System monitoring is necessary to ensure the reliable operation of power grids, and state estimation is used in system monitoring to best estimate the power grid state through analysis of meter measurements and power system models. Various techniques have been developed to detect and identify bad measurements, including interacting bad measurements introduced by arbitrary, nonrandom causes. At first glance, it seems that these techniques can also defeat malicious measurements injected by attackers. In this article, we expose an unknown vulnerability of existing bad measurement detection algorithms by presenting and analyzing a new class of attacks, called false data injection attacks , against state estimation in electric power grids. Under the assumption that the attacker can access the current power system configuration information and manipulate the measurements of meters at physically protected locations such as substations, such attacks can introduce arbitrary errors into certain state variables without being detected by existing algorithms. Moreover, we look at two scenarios, where the attacker is either constrained to specific meters or limited in the resources required to compromise meters. We show that the attacker can systematically and efficiently construct attack vectors in both scenarios to change the results of state estimation in arbitrary ways. We also extend these attacks to generalized false data injection attacks , which can further increase the impact by exploiting measurement errors typically tolerated in state estimation. We demonstrate the success of these attacks through simulation using IEEE test systems, and also discuss the practicality of these attacks and the real-world constraints that limit their effectiveness.

Improvement of Seismic Parameter Estimation for the Earthquake Early Warning System

The earthquake early warning system was put into operation in Japan in order to stop Shinkansen trains as rapidly as possible before the strike of large tremors, in the case of an earthquake. The present paper overviews current earthquake early warning system configuration and functions and evaluates the accuracy of epicenter estimation by that same system by using the latest datasets. The estimation error (rms) of epicentral distance in the present system is 0.324 on a logarithmic scale. By re-determination of the coefficients of correlation equation for estimation, it was confirmed that the estimation error was reduced by 13%.

A Solar-Hydrogen Fuel-Cell Home and Research Platform

Abstract The Solar-Hydrogen Fuel-Cell Home located at the United States Merchant Marine Academy, one of America’s five federal service academies, is believed to be the first of its kind in New York State and perhaps the nation. It represents a synergy of alternative-energy equipment that uses the sun’s energy to create electricity to power the home or surrounding community. Furthermore, it creates hydrogen gas that can be used as a fuel for a variety of applications. The hydrogen produced has two main purposes. First, the hydrogen supplies a fuel cell that produces electricity for the home in the evenings or during days when it is cloudy. Second, the hydrogen can be used to fill up the fuel tank of an environmentally friendly hydrogen-powered automobile after a typical day of operation. There are three primary objectives of this paper. The first objective is to provide a technical overview of the home’s energy systems. This includes an overview of the various monitoring devices, followed by a discussion on how these types of energy systems can help meet the needs of sustainability and energy independence. Building upon this information, the second objective is to perform an analysis of the current system configuration, including the solar array capacity, fuel cell size, and quantity of hydrogen that can be produced versus what is required for the home to be energy self-sufficient. The third objective is to explore existing maritime and military applications and to suggest future applications that may stem from research of this cutting-edge Solar-Hydrogen Fuel-Cell Home and research platform.

Signal and noise transfer properties of CMOS based active pixel flat panel imager coupled to structured CsI:Tl

Complementary metal-oxide-semiconductors (CMOS) active pixel sensors can be optically coupled to CsI:Tl phosphors forming a indirect active pixel flat panel imager (APFPI) for high performance medical imaging. The aim of this work is to determine the x-ray imaging capabilities of CMOS-based APFPI and study the signal and noise transfer properties of CsI:Tl phosphors. Three different CsI:Tl phosphors from two different vendors have been used to produce three system configurations. The performance of each system configuration has been studied in terms of the modulation transfer function (MTF), noise power spectra, and detective quantum efficiency (DQE) in the mammographic energy range. A simple method to determine quantum limited systems in this energy range is also presented. In addition, with aid of monochromatic synchrotron radiation, the effect of iodine characteristic x-rays of the CsI:Tl on the MTF has been determined. A Monte Carlo simulation of the signal transfer properties of the imager is also presented in order to study the stages that degrade the spatial resolution of our current system. The effect of using substrate patterning during the growth of CsI:Tl columnar structure was also studied, along with the effect of CsI:Tl fixed pattern noise due to local variations in the scintillation light. CsI:Tl fixed pattern noise appears to limit the performance of our current system configurations. All the system configurations are quantum limited at 0.23 microC/kg with two of them having DQE (0) equal to 0.57. Active pixel flat panel imagers are shown to be digital x-ray imagers with almost constant DQE throughout a significant part of their dynamic range and in particular at very low exposures.

Review, Analysis, and Hazard Mitigation of the Life-Support Oxygen System on Royal Australian Air Force P-3 Orion Aircraft

Abstract To ensure te ongoing safe operation of the Royal Australian Air Force (RAAF) P-3 Orion life-support oxygen system, a system review was completed that included a failure modes and effects analysis combined with an oxygen hazards and fire risk analysis. Though the RAAF P-3 Orion oxygen system has been operational for many years, the results of these analyses clearly identified many deficiencies in the current system configuration, thus demonstrating the value of the formal analysis approach. Design, procedural, maintenance, and material issues were all identified and addressed in the course of this process. This paper provides a brief summary of the analyses performed, the results obtained, risk tables generated, and their use leading to the recommendations for changes incorporated onto RAAF P-3 Orion aircraft that resulted from this work.

Multisensory Feedback in Support of Pilot-Automation Coordination: The Case of Uncommanded Mode Transitions

The introduction of advanced automation technology to the modern cockpit has created new attentional and monitoring demands for pilots whose primary role has shifted towards supervisory control. Observed breakdowns in pilots' mode awareness, i.e., in their knowledge and understanding of the current and future system configuration, suggest that these demands are not adequately supported by existing automation feedback. In particular, current feedback fails to highlight unexpected changes in system status and behavior due, in part, to designers' tendency to increasingly rely on focal visual attention instead of exploiting the wide range of sensory modalities available to human operators. In this study, we examined the feasibility and effectiveness of multisensory feedback for providing attentional guidance to pilots in case of unexpected mode transitions. Tactile or peripheral visual cues were presented in the context of a simulated flight scenario involving varying levels of competing visual demands. The results of this study indicate that the introduction of multisensory feedback is one effective way of capturing pilots' attention without necessarily affecting their performance on concurrent tasks.

Quantitative photogrammetric analysis of digital underwater video imagery

This paper presents a photogrammetric model for digital underwater video imagery, which has been mostly applied to qualitative analysis in the marine environment. With this model, quantitative analysis of underwater images is possible, e.g., to locate positions, calculate sizes, and measure shapes of objects from image features. The underwater photogrammetric model is based on a three-dimensional optical ray tracing technique which rigorously models imaging systems with multilens configurations and multiple refractions. The calibration procedure with two independent phases has been proven to be efficient in simplifying the computation and improving the calibration accuracy. With the current imaging system configuration and photogrammetric model, an accuracy of 0.8 cm in lateral directions and 1.2 cm along the depth direction for objects located about 2-3 m from the camera system in the object space is attainable. A PC-based digital underwater photogrammetric prototype system has been developed to implement the underwater photogrammetric model.

An inverse heat conduction algorithm for the thermal detection of arbitrarily shaped cavities

An inverse geometric heat conduction problem algorithm is presented for the detection of irregular shaped cavities located within irregular shaped bodies. The inverse problem is solved using the additional information provided by specifying a Cauchy condition at the exposed boundary. The exposed surface temperature distribution is determined experimentally using an infrared scanner. The inverse problem solution algorithm is based on solving a sequence of forward steady state heat conduction problems and defining a residual measuring the difference between actual and computed boundary conditions under the current system configuration. The boundary element method is used to solve the forward problems. The iterative procedure is automated through the use of a multivariable nonlinear solver along with the linear and cubic spline based Anchored Grid Pattern (AGP) method described herein. Numerical simulation is used to investigate the practical implementation of the AGP algorithm in detecting a small cavity. T...