20,380 research outputs found
Linguistic Reflection in Java
Reflective systems allow their own structures to be altered from within. Here
we are concerned with a style of reflection, called linguistic reflection,
which is the ability of a running program to generate new program fragments and
to integrate these into its own execution. In particular we describe how this
kind of reflection may be provided in the compiler-based, strongly typed
object-oriented programming language Java. The advantages of the programming
technique include attaining high levels of genericity and accommodating system
evolution. These advantages are illustrated by an example taken from persistent
programming which shows how linguistic reflection allows functionality (program
code) to be generated on demand (Just-In-Time) from a generic specification and
integrated into the evolving running program. The technique is evaluated
against alternative implementation approaches with respect to efficiency,
safety and ease of use.Comment: 25 pages. Source code for examples at
http://www-ppg.dcs.st-and.ac.uk/Java/ReflectionExample/ Dynamic compilation
package at http://www-ppg.dcs.st-and.ac.uk/Java/DynamicCompilation
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Reform and Regulation of the Electricity Sectors in Developing Countries
Reform and Regulation of the Electricity Sectors in Developing Countrie
Generators and closed classes of groups
We show that in the category of groups, every singly-generated class which is
closed under isomorphisms, direct limits and extensions is also
singly-generated under isomorphisms and direct limits, and in particular is
co-reflective. We also establish several new relations between singly-generated
closed classes.Comment: 22 page
Carbon Pricing in New York ISO Markets: Federal and State Issues
New Yorkâs Clean Energy Standard (âCESâ), adopted in August 2016, aims to steer the stateâs electricity sector away from carbon-intensive generation sources. It supports low-carbon alternatives by requiring retail electricity suppliers to purchase credits, the proceeds from which are paid to renewable and nuclear generators. Recognizing that this will affect the operation of wholesale electricity markets, New Yorkâs electric transmission grid operator (the âNew York Independent System Operatorâ or âNYISOâ) has commenced a review to assess possible means of incorporating the cost of carbon emissions into market prices. This Article explores two approaches to carbon pricing in NYISO markets: the first would involve NYISO adopting a carbon price of its own initiative with a view to improving the operation of wholesale electricity markets (âApproach 1â), while the second would involve adoption of a carbon price designed to reflect and harmonize state-level policies aimed at reducing electricity sector emissions (âApproach 2â). Under either approach, NYISO would adopt a per megawatt hour carbon price and use it to establish a fee for each generating unit, consistent with its emissions profile. This fee would be added to the prices generators bid into the wholesale electricity market and those adjusted prices used by NYISO to determine the dispatch order. The result would likely be a re-ordering of dispatch, with high-emitting generators dispatched (and paid) less frequently, and cleaner alternatives more frequently. Our proposal, while conceptually simple, is likely to be difficult to implement
Performance Measures to Assess Resiliency and Efficiency of Transit Systems
Transit agencies are interested in assessing the short-, mid-, and long-term performance of infrastructure with the objective of enhancing resiliency and efficiency. This report addresses three distinct aspects of New Jerseyâs Transit System: 1) resiliency of bridge infrastructure, 2) resiliency of public transit systems, and 3) efficiency of transit systems with an emphasis on paratransit service.
This project proposed a conceptual framework to assess the performance and resiliency for bridge structures in a transit network before and after disasters utilizing structural health monitoring (SHM), finite element (FE) modeling and remote sensing using Interferometric Synthetic Aperture Radar (InSAR). The public transit systems in NY/NJ were analyzed based on their vulnerability, resiliency, and efficiency in recovery following a major natural disaster
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Electricity Sector Reform in Developing Countries: A Survey of Empirical Evidence on Determinants and Performance
This paper reviews the empirical evidence on electricity reform in developing countries. We find that country institutions and sector governance play an important role in success and failure of reform; reforms appear to have increased operating efficiency and expanded access to urban customers; they have to a lesser degree passed on efficiency gains to customers, tackled distributional effects, or improved rural access. Moreover, some of the literature is not methodologically robust or on a par with general development economics literature and findings on some issues are limited and inconclusive while some important areas are yet to be addressed. Until we know more, implementation of reforms will be more based on ideology and economic theory rather than solid economic evidence.The World Bank Electricity Research Programme and the CMI Electricity Project (IR-45
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