Introduction to web computing
The World Wide Web offers many opportunities for computing in science and engineering. Interpreting my charge as department editor quite broadly, I'd like to review some of these possibilities. If I omit areas of particular interest to you, please let me know.
A Model Reduction Web Environment for Very Large Linear Dynamical Systems
We describe a prototype web service for model reduction of very large-scale linear systems, with dimension in the order of millions of states, that includes a user-friendly interface designed so that the computation can be easily performed via the HTTP protocol. Access via a web browser isolates the user of the service from the complexities of installing and using the parallel model reduction codes and the maintenance of the hardware. In case the routines are found to be appropriate for the problem the user needs to solve, the library can be then downloaded and installed on the user's own computing resources. This paper illustrates the major issues of the access procedure by means of graphical examples, and describes the structure and implementation of the remote model reduction service. The service is offered in a cluster of Linux machines. 1. Introduction. The development of the Internet and its popularization via the world wide web (www) is producing a tremendous impact in our society. The www is nowadays employed to consult databases, retrieve documents, submit jobs to remote systems, and access a large number of services which is continuously growing. The extension of these services has recently reached the area of scientific computing in projects like NetSolve (4), LAPK (http://lapk3.hsc.usc.edu/lapk), the SLICOT Web Environment (16), NPACI (https://hotpa- ge.npaci.edu), CACTUS (http://www.cactuscode.org), and EOT-PACI (http://www.eot.org), among others. Many of these efforts can be generically classified as problem-solving envi- ronments or computational science portals (18). A related, extensive survey of applications of web-computing and grid-computing can be consulted, e.g., in (10). In this paper we further explore the www and the HTTP protocol as a means of offering an enhanced service for scientific computing to a certain cluster of the scientific and engineering community. Specifically, we offer a computational service for model reduction of large-scale linear systems, with potentially even millions of states, on a parallel cluster. The idea here is to provide an easy way for remote users to interact with the model reduction codes via the www so that the service becomes a demonstrator of the capabilities of the parallel model reduction library. Note that a usual case is that of a user with a problem that needs to be solved, who has to search for a likely solver (in the form of a code or a library), read the manuals, install the application (after having solved compatibility problems with the compiler, operating system, or even architecture), write the interface programs, and run it just to then discover that the code is not the appropriate one to solve his/her problem. Thus, the main advantage of providing this service via the www is that the end-user remains completely isolated from the complexities of the software and the hardware system, and the maintenance of both. Then, in case the routines are evaluated as satisfactory by the user, the library itself can be downloaded and installed on any (parallel) architecture ⁄ Peter Benner was supported by the DFG Research Center "Mathematics for key technologies" (FZT
Inference and Evidence in Archaeology: A Discussion of the Conceptual Problems
Publisher Summary This chapter dicsusses the general features of scientific inference and explains the way inference has been discussed by archaeologists. It presents an explication of current problems in the various areas: (1) the justification of archaeological conclusions, (2) the concepts of archaeological evidence, and (3) the undeveloped relations between archaeological theory and archaeological evidence. The chapter defines these problems and explains the way to resolve them. To resolve many of the problems surrounding uncertain links between inference and evidence, archaeologists should develop a rigorous model that specifies the way information about the past is transmitted to the present via material remains. The chapter presents the structure of such a model. However, establishing relevant data to support conclusions about past phenomena is only part of the overall process of generating archaeological knowledge. Some of the processes responsible for producing the material remains that archaeologists manipulate in assembling evidence to support claims about past phenomena are described in the chapter.