216 research outputs found
Limiting Ramp Rate of Wind Power Output using a Battery Based on the Variance Gamma Process
Abstract. A battery system is designed to reduce violations of ramping limit due to severe and long ramps of wind power output. The power rating, battery capacity, and operational policies of the battery are decided based on the assumption that the wind power output follows the Variance Gamma (V.G.) process over short time interval. The histogram of the ramp rates of wind power follows the symmetric Laplace distribution. Furthermore, ramp rates have independent and stationary increments, and their variances are proportional to the time interval. Consequently, the wind power output can be modelled as a simple form of the V.G. process. Battery operational oplicies based on the V.G. process are tested using statistics representing the sum of all wind power outputs from wind farms in the Electric Reliability Council of Texas (ERCOT). It is found that the battery can essentially eliminate violations of ramping limits due to severe ramp events. Furthermore, in this operation, it is discovered that the power rating influences the ramp limiting performance of the battery more than battery storage rating
Transmission Investment Coordination using MILP Lagrange Dual Decomposition and Auxiliary Problem Principle
This paper considers the investment coordination problem for the long term
transmission capacity expansion in a situation where there are multiple
regional Transmission Planners (TPs), each acting in order to maximize the
utility in only its own region. In such a setting, any particular TP does not
normally have any incentive to cooperate with the neighboring TP(s), although
the optimal investment decision of each TP is contingent upon those of the
neighboring TPs. A game-theoretic interaction among the TPs does not
necessarily lead to this overall social optimum. We, therefore, introduce a
social planner and call it the Transmission Planning Coordinator (TPC) whose
goal is to attain the optimal possible social welfare for the bigger
geographical region. In order to achieve this goal, this paper introduces a new
incentive mechanism, based on distributed optimization theory. This incentive
mechanism can be viewed as a set of rules of the transmission expansion
investment coordination game, set by the social planner TPC, such that, even if
the individual TPs act selfishly, it will still lead to the TPC's goal of
attaining overall social optimum. Finally, the effectiveness of our approach is
demonstrated through several simulation studies
Dynamic Energy Management
We present a unified method, based on convex optimization, for managing the
power produced and consumed by a network of devices over time. We start with
the simple setting of optimizing power flows in a static network, and then
proceed to the case of optimizing dynamic power flows, i.e., power flows that
change with time over a horizon. We leverage this to develop a real-time
control strategy, model predictive control, which at each time step solves a
dynamic power flow optimization problem, using forecasts of future quantities
such as demands, capacities, or prices, to choose the current power flow
values. Finally, we consider a useful extension of model predictive control
that explicitly accounts for uncertainty in the forecasts. We mirror our
framework with an object-oriented software implementation, an open-source
Python library for planning and controlling power flows at any scale. We
demonstrate our method with various examples. Appendices give more detail about
the package, and describe some basic but very effective methods for
constructing forecasts from historical data.Comment: 63 pages, 15 figures, accompanying open source librar
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A Tale of Two Industroyers: It was the Season of Darkness
In this paper, we study two pieces of malware that attempted to create blackouts in Ukraine. In particular, we design and develop a new sandbox that emulates different networks, devices, and other characteristics so that we can execute malware targeting substation equipment and understand in detail the specific sequence of actions the attackers could perform on substation equipment. We also study the effects that future similar malware can have. Our findings include new malware behavior not previously documented (such as the detailed algorithm for the MMS protocol payload) and an illustration of how attacking different targets will produce different effects
Comparative Analysis of Viral Gene Expression Programs during Poxvirus Infection: A Transcriptional Map of the Vaccinia and Monkeypox Genomes
Poxviruses engage in a complex and intricate dialogue with host cells as part of their strategy for replication. However, relatively little molecular detail is available with which to understand the mechanisms behind this dialogue.We designed a specialized microarray that contains probes specific to all predicted ORFs in the Monkeypox Zaire (MPXV) and Vaccinia Western Reserve (VACV) genomes, as well as >18,000 human genes, and used this tool to characterize MPXV and VACV gene expression responses in vitro during the course of primary infection of human monocytes, primary human fibroblasts and HeLa cells. The two viral transcriptomes show distinct features of temporal regulation and species-specific gene expression, and provide an early foundation for understanding global gene expression responses during poxvirus infection.The results provide a temporal map of the transcriptome of each virus during infection, enabling us to compare viral gene expression across species, and classify expression patterns of previously uncharacterized ORFs
The body unbound: ritual scarification and autobiographical forms in Wole Soyinka’s Aké: the years of childhood
The scarification in Aké is invested with major significance apropos Soyinka’s ideas on African
subjectivity. Scarification among the Yoruba is one of the rites of passage associated with personal
development. Scarification literally and metaphorically “opens” the person up socially and cosmically.
Personal formation and self-realization are enabled by the Yoruba social code brought into being
by its mythology. The meaning of the scarification incident in Aké is profoundly different. Determined
by the form of autobiography which creates a self-constituting subject, the enabling Yoruba sociocultural
context is elided. The story of Soyinka’s personal development is allegorical of the story
of the development of the modern African subject. For Soyinka, the African subject is a rational
subject whose constitution precludes the splitting of the scientific and spiritual which is a consequence
of the Cartesian rupture. The African subject should be open to other subjects and the object
world. Subjectivity constituted by the autobiographical mode closes off the opening up symbolically
signalled by scarification.Web of Scienc
Monsters: interdisciplinary explorations in monstrosity
There is a continued fascination with all things monster. This is partly due to the popular reception of Mary Shelley’s Monster, termed a “new species” by its overreaching but admiringly determined maker Victor Frankenstein in the eponymous novel first published in 1818. The enduring impact of Shelley’s novel, which spans a plethora of subjects and genres in imagery and themes, raises questions of origin and identity, death, birth and family relationships as well as the contradictory qualities of the monster. Monsters serve as metaphors for anxieties of aberration and innovation. Stephen Asma (2009) notes that monsters represent evil or moral transgression and each epoch, to speak with Michel Foucault, evidences a “particular type of monster” (2003, 66). Academic debates tend to explore how social and cultural threats come to be embodied in the figure of a monster and their actions literalize our deepest fears. Monsters in contemporary culture, however, have become are more humane than ever before. Monsters are strong, resilient, creative and sly creatures. Through their playful and invigorating energy they can be seen to disrupt and unsettle. They still cater to the appetite for horror, but they also encourage us to feel empathy. The encounter with a monster can enable us to stop, wonder and change our attitudes towards technology and our body and each other. This commentary article considers the use of the concepts of ‘monsters’ or ‘monstrosity’ in literature, contemporary research, culture and teaching contexts at the intersection of the Humanities and the Social Sciences
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