PURR - The Persistent URL Resource Resolver

URLs have a precarious functional lifespan. They resolve the intended target (web page, PDF, audio stream, and so on) only so long as the target is available, otherwise they'll point to a dead end. Unfortunately, because companies fold, management changes, URL hostnames change, pages move, services are upgraded and reorganized, content becomes obsolete, and a host of other reasons, reliable, persistent URLs are the exception to the norm. We implemented PURR to provide persistent URLs to documents in our eprint archives. (See http://library.caltech.edu/digital)

An Eprints Apache Log Filter for Non-Redundant Document Downloads by Browser Agents

Web log files record a vast amount of information and much of it just gets in the way of meaningful observational studies on usage. It is therefore necessary to filter out the junk in a deliberate way before making statements on how the web is being used. This report describes the methods and scripts used to accomplish apache web log filtering and report generation. It is open to scrutiny and freely available for others to use

Genetic algorithms applied to the scheduling of the Hubble Space Telescope

A prototype system employing a genetic algorithm (GA) has been developed to support the scheduling of the Hubble Space Telescope. A non-standard knowledge structure is used and appropriate genetic operators have been created. Several different crossover styles (random point selection, evolving points, and smart point selection) are tested and the best GA is compared with a neural network (NN) based optimizer. The smart crossover operator produces the best results and the GA system is able to evolve complete schedules using it. The GA is not as time-efficient as the NN system and the NN solutions tend to be better

Online Journals: Utility of ToCs vs. Fulltext

The Caltech Library System (CLS) has maintained an extensive list of online journal websites for several years. The online journal list has grown to over 3000 entries, representing a mixture of free and subscription-based fulltext journals, as well as websites featuring tables of contents and abstracts. During the winter of 1999/2000, the online journals list was converted to an online journals database. Additional user functionality was added, without loss of previous features. In a previous study, search engines were employed to map the adoption rates of online journals into the web pages of research groups and individuals on the Caltech campus. It was established that the vast majority of online journal use on-campus was through the access avenues presented by the library, the online catalog and the online journals database. One of the new features introduced in the online journals database was an ability to limit displays to journals containing fulltext. Anecdotal evidence has been less than clear-cut with regard to the utility of non-fulltext resources. This study will allow for a thorough analysis of the question with hard data. It should be feasible to determine if there are discipline-based preferences or if personal preferences are the controlling factor. Analysis of the web server logs will also allow for a direct comparison of user preferences for searching and browsing. Again, we expect to be able to determine if there is a subject-specific bias or if behaviors are more individually idiosyncratic. Results of the study will inform the further development of the CLS online journal efforts - database development, online journal promotion, new candidates for licensing. The technologies employed in this project are well documented and may be exploited by other libraries seeking to gather empirical data for collection decisions and web development efforts

Unlocking Potential: Results of a National Survey of Postsecondary Education in State Prisons

Examines enrollment, instruction, eligibility, and funding for postsecondary correctional education as a way to reduce recidivism. Calls for increasing capacity, aligning programs with state education systems and workforce needs, and expanding access

An approach to rescheduling activities based on determination of priority and disruptivity

A constraint-based scheduling system called SPIKE is being used to create long term schedules for the Hubble Space Telescope. Feedback for the spacecraft or from other ground support systems may invalidate some scheduling decisions and those activities concerned must be reconsidered. A function rescheduling priority is defined which for a given activity performs a heuristic analysis and produces a relative numerical value which is used to rank all such entities in the order that they should be rescheduled. A function disruptivity is also defined that is used to place a relative numeric value on how much a pre-existing schedule would be changed in order to reschedule an activity. Using these functions, two algorithms (a stochastic neural network approach and an exhaustive search approach) are proposed to find the best place to reschedule an activity. Prototypes were implemented and preliminary testing reveals that the exhaustive technique produces only marginally better results at much greater computational cost

Design Goals for Federated Services across Caltech CODA

Caltech CODA currently exists as 15 individual archives. Fortunately, each is an OAI Data Provider which allows OAI Service Providers the opportunity to federate the content into a central database for searching or other end user services. Ideally though, Caltech Library will design a Union Catalog using the OAI-PMH. This central database would provide a local implementation of a federated search interface, using a modification of eprints.org software. The Catalog would also support other eprints.org features out of the box: RSS, Browse by Year, Author, Subject and act as a single CODA Data Provider for outside Service Providers, such as DP9, Celestial and Google Scholar

Flexible Tuning Software: Beyond Equal Temperament

The premise of this creative Capstone project was to develop a computer instrument that is capable of tuning itself flexibly in such a way as to not require a tempering of the Western scale, as is necessary for fixedly tuned instruments. The difficulty in creating such a system of tuning arises from the mathematical paradox of the musical harmonic series, which is the sequence of frequencies that sound naturally as overtones over a fundamental pitch. They follow a proportional pattern of 1:2, 2:3, 3:4, etc. These small-integer ratios of frequencies represent the consonant (in-tune) harmonic intervals. When an interval does not have a small-integer ratio between its notes, it is perceived as “out-of-tune,” and the two frequencies will compete with each other. The problem becomes apparent when the ratios are used to create the Western scale on a fixed instrument. When tuning such an instrument (i.e. a piano), the intervals inherently cannot all be tuned justly, or according to the appropriate proportions. The nature of the ratios does not allow larger intervals to be explained exactly by the smaller intervals, though they are expected to coexist and be used simultaneously in Western music. For example, an octave in music is the equivalent of three major thirds; however, the justly tuned octave (2:1) is not equal to the sum of three major thirds (5:4); 5:43=125:64, not 2:1. The difference, then, between notes tuned in terms of different intervals is known as a comma, and the attempts to distribute this comma are called temperaments. To overcome the impossibility of perfectly consonant temperaments, we have created a computer program that can function as a self-tuning instrument by mathematically calculating the frequency of each pitch played in relation to the pitch preceding it. Though this allows every interval between sequentially played notes to be in tune, it does mean that pitches are not fixed, and rather are flexible and changing as a piece progresses. The program possesses the capability to play several historical fixed temperaments, namely Pythagorean, Quarter-Comma Meantone, Werckmeister III, and Equal Temperament. However, it also is capable of playing in two non-fixed tuning systems, distinguished as Sequential Tuning and Flexible Tuning. The Sequential Tuning system uses the ratios in the harmonic series to tune each note proportionally to the most recent note pressed. It is ideal for educational purposes, clearly demonstrating the flexibility of the program, but is less practical for tuning purposes, as it disregards held notes and tunes solely based on the notes pressed while the note is held, creating obtrusive dissonances between any held note and the notes tuned sequentially before it is released. The Flexible Tuning system remedies this issue by first tuning notes based on a held note, and if there is no note being held, then on the most recent note pressed. This eliminates the noticeable dissonances of the Sequential Tuning system, while still tuning each note flexibly and in real time based on its interval relationships to other notes played before and at the same time as it. In this way, every interval sounding is the appropriate small integer ratio for that interval in the harmonic series