13961083
Experimental tests of competitive markets for electric power
Testing the performance of electricity markets using POWERWEB has already shown that relatively inexperienced players can identify and exploit market power in load pockets. When transmission constraints are not binding, however, auctions with six players have been shown to be efficient. There is evidence from operating electricity markets that prices can be driven above competitive levels when the largest supplier controls less than 20% of total installed capacity. This is accomplished by causing price spikes to occur. In experiments, uncertainty about the actual load and paying standby costs regardless of whether or not a unit is actually dispatched contribute to volatile price behavior. The objective of this paper is to investigate characteristics of a market that affect price volatility. The tests consider three different sets of rules for setting price when there are capacity shortfalls, and the following four market structures: load is responsive to price; price forecasts are made before market settlement; a day-ahead market and a balancing market auction; and suppliers are paid actual offers (a discriminatory auction).
6798576
Locational pricing and scheduling for an integrated energy-reserve market
It is well known that given a network that can become constrained on voltage or real power flows, reserves must also be spatially located in order to handle all credible contingencies. However, to date, there is no credible science-based method for assigning and pricing reserves in this way. Presented in this paper is a new scheduling algorithm incorporating constraints imposed by grid security considerations, which include one base case (intact system) and a list of possible contingencies (line-out, unit-lost, and load-growth) of the system. By following a cost-minimizing co-optimization procedure, both power and reserve are allocated spatially for the combined energy and reserve markets. With the Lagrange multipliers (dual variables) obtained, the scheduling algorithm also reveals the locational shadow prices for the reserve and energy requirements. Unlike other pricing and scheduling methods in use, which are usually ad-hoc and are based on engineering judgment and experience, this proposed formulation is likely to perform better in restructured markets when market power is a potential problem. An illustrative example of a modified IEEE 30-bus system is used to introduce concepts and present results.
37344904
Power System Bidding Tournaments for a Deregulated Environment
In this paper we describe certain tools for understanding and operating power systems in a deregulated environment. Many of the current models for this competitive market that employ an independent system operator (ISO) for controlling transmission, ensuring fair access and security, and providing a spot market for power will be studied. This centrally-dispatched power pool also ensures that generation meets demand based on bids submitted daily from independent generators (and from customers offering interruptible loads). Currently, most I S 0 bidding models allow only a single bid per day. In this paper, we present an asynchronous bidding scheme as a possible alternative. In particular, we examine the effects of including a feedback mechanism such that upon receiving generation levels from the ISO, independent generators (IGs) be allowed to modify their bid if they so desire. This competitive or ‘sequential’ bidding process should be allowed to take place each day for a predetermined period of time; in this way, IGs will have a chance to compete and hopefully optimize their profit margins. This paper also discusses the development tools necessary for examining the effects of different bidding processes on the I S 0 model and evaluating their capability of driving the market to an efJicient state of operation.
10283778
An Internet-based platform for testing generation scheduling auctions
The paper describes the uses and architecture of a network-centered computing-rich software platform called PowerWeb. PowerWeb was designed and built as a simulation environment for experimentally testing various power exchange auction markets through tournaments. It is designed to host simulations of a competitive "day-ahead" electric energy market in the content of a restructured electric power industry. The PowerWeb environment is meant to be flexible so as to accommodate different "rules of the game". The authors describe its interactive, distributed and Web-based character.
6233472
Underlying technical issues in electricity deregulation
This paper reports on the results of an attempt by the Power Systems Engineering Research Center (Pserc) and EPRI to determine the technical tools missing in currently unfolding electric power restructuring scenarios. Needed tools have been divided into the functional categories of generation, transmission and distribution. In each category, there seems to be a common need to interface existing technical tools with the new economic unbundling.
17884360
Experimental results for single period auctions
The objective of the paper is to present experimental results for testing the performance of different auction mechanisms related to the introduction of competitive markets for the generation of electricity. The research is based on the concept of smart markets introduced by Vernon Smith (K.A. McCabe et al., 1991) and a simulation model (PowerWeb) of a realistic bulk power system. There are unique physical aspects associated with the supply of electricity (e.g. required instantaneous matching of supply and demand, unintended congestion of parallel transmission routes and maintenance of system stability in response to disturbances). As a result, traditional theories of efficient markets and auction structures developed for other commodities may not be efficient if applied without alteration to markets for electricity. Conversely, current utility rules of operation developed for a centrally planned regime may not be appropriate in a competitive environment. The research does not address the issues of multiperiod operations (unit commitment) and multidimensional markets (ancillary services), and considers only real power in a single time period. The main objective is to test three alternative auction mechanisms when market power is a potential problem. This situation occurs when limits on transmission lines are binding to form a load pocket in which demand is met by a few (in this case two) generators.
33726107
A menger-like property of tree-width: The finite case
The notion of tree-width was introduced by Robertson and Symour. A graph has tree-width ≦ w if it admits a tree-decomposition of tree-width ≦ w. We prove here that if G is finite and has tree-width ≦ w then it admits a tree-decomposition of tree-width ≦ w which satisfies a certain Menger-like condition. This result will be used in a future paper on well-quasi-ordering infinite graphs of bounded tree-width.
14742276
Finger tracking for the Digital Desk
One trend in computing environments today is to move towards more 'natural' interaction. Another is to make hardware invisible to the user. Both these ideas converge into ubiquitous computing-the Digital Desk is an example of this idea. In this paper, we concentrate on an input device for the Digital Desk, namely the user's fingertip, which is made to act like a mouse. Tracking such an input device is common to a number of augmented reality environments and involves vision and motion analysis. However, previous attempts have focused more on the vision aspect of tracking general objects than on using the information already known about the user's hand, which is the approach taken in this paper. We adopted the goal of tracking the user's fingertips as fast as possible in real time, so that the system could be compared with other input devices by using models such as Fitts' law. Our system is shown to comply with the law adequately.
45805701
A survey of linkless embeddings
12699179
Developing the Software Engineering Team
Teamwork is often considered one of the most important "generic skills" that we can provide to graduates entering the information technology profession. Often though, through the rush of covering important content, we short change our students by giving them limited opportunities to learn how to work effectively in teams. Students also often complain that although they are expected to work in teams on projects, they are never given any advice or guidance on how to work in a team (Hart and Stone, 2002). Or, if they are given guidance, it is often from a business perspective that students find difficult to integrate into their software development practice.In this paper we discuss a course-spanning initiative to help students learn teamwork skills. This initiative starts in first year by emphasising a core set of skills directly related to working in teams. These skills are applied in small software development teams, with close tutor supervision focusing students on teamwork rather than upon individual software development. The theme then continues into second and third year where the growing sophistication of the students' teamwork skills is complemented by increasing their independence and requiring students to apply a professional software engineering process as a development team. By the end of their course students are then in a position to work together effectively solving complex problems for a real industry client.
18563409
A conditional density error model for the statistical analysis of microarray data
MOTIVATION
In many microarray experiments, relatively few intra- and inter-array replicate measurements are made due to significant cost limitations and sample availability. Compounding this problem is a lack of robust statistical methods for analyzing gene expression data with limited experimental replicates. As a result, the interpretation of the results of these experiments are difficult with little understanding of the probability of type I and type II errors.


RESULTS
The variability in a series of replicate microarray measurements was modelled using a combination of parametric and non-parametric methods. A 3-dimensional surface was created for the conditional distribution of the variability given the mean signal intensity in both the Cy3 and Cy5 channels. The results were used as the basis for developing statistical methods for analyzing gene expression data with limited experimental replicates.


AVAILABILITY
The statistical analysis scripts are available upon request.