Mass Storage Facilities Research Articles

The Study of Diluted Magnetic Semiconductor: The Case of Manganese Doped Gallium Nitride

The diluted magnetic semiconductor, (Ga, Mn) N has recently attracted intense research interest for the purpose of spintronics application. The material is believed to circumvent the difficulty of combining data processing and mass storage facilities in a single crystal besides solving non-volatility problems. The concentration x, of Mn that substitutes for a fraction of Ga in the compound is thought to contribute a large concentration of magnetic moments and holes. The material studied is focused on dilute magnetic semiconductors (DMS) like <i>Ga_1-XMn<SUB>X</SUB>N</i> that play a key role in semiconductor spintronics. Due to their ferromagnetic properties they can be used in magnetic sensors and as spin injectors. The basic problems for applications are, however, the relatively low Curie temperatures of these systems. Therefore, we focus on the understanding of the magnetic properties and on a reliable calculation of Curie temperatures from first principles. We have developed a theoretical framework for calculating critical temperatures by combining first principles calculations and in terms of the Ruderman–Kittel–Kasuya–Yosida quantum spin model in Green’s function approach. Magnetic properties of the group-III nitride semiconductors are introduced here with basic material parameters (temperature, concentration, heat capacity, etc. Temperature dependencies of the spin wave specific heat, inverse magnetic susceptibility and reduced magnetization are determined. Therefore, the dependence of the Neel temperature on the manganese ion concentration is linear thus for our calculation the highest Neel temperature obtained T=146.3k within the concentration of 0.2.

Targeting and design for batch regeneration and total networks

Resource conservation for batch processes is gaining good attention in recent years. This is mainly due to the recent trend in chemical engineering that focuses on product engineering, as well as in the rise of various low volume and high value-added products (e.g. pharmaceutical, specialty chemicals, etc.) in the market. In this study, a systematic procedure to perform targeting and design of a batch resource conservation network (RCN) involving material regeneration and waste treatment (also known as a total RCN) is proposed. The procedure is applicable for all fixed-schedule-type batch RCNs with mass storage facilities. Literature examples are used to elucidate the proposed procedure.

The Data-Logging System of the Trigger and Data Acquisition for the ATLAS Experiment at CERN

The ATLAS experiment is getting ready to observe collisions between protons at a centre of mass energy of 14 TeV. These will be the highest energy collisions in a controlled environment to-date, to be provided by the Large Hadron Collider at CERN by mid 2008. The ATLAS Trigger and Data Acquisition (TDAQ) system selects events online in a three level trigger system in order to keep those events promising to unveil new physics at a budgeted rate of ~200 Hz for an event size of ~1.5 MB. This corresponds to a reduction of O(105) from the initial bunch-crossing rate of 40 MHz at nominal operating conditions. This paper focuses on the data-logging system on the TDAQ side, the so-called Sub-Farm Output (SFO) system. It takes data from the Event Filter farm, which is the third level trigger, and it streams and indexes the events into different files, according to each event's trigger path. The data files are moved to CASTOR, the central mass storage facility at CERN. The final TDAQ data-logging system has been installed using 6 Linux PCs, holding 24 disks of 500 GB each, managed by three RAID controllers on each PC. The data-writing is managed in a controlled round-robin way among three independent filesystems associated to a distinct set of disks, managed by a distinct RAID controller. This design allows fast I/O, which together with a high speed network permits to minimize the number of SFO nodes. We report here on the functionality and performance requirements on the system, our experience with commissioning it and on the performance achieved,

Digital Library for Access to Rare Materials. From pilot projects to national digitisation programmes

More than ten years ago, a first image digitisation product was published by the National Library of the Czech Republic in co-operation with an almost unknown small software company. It was a CD-ROM requested by UNESCO for its Memory of the World programme. After that there were many tests concerning digitisation devices and another two CD-ROM projects were completed to present two interesting manuscripts with rich description metadata related to all the structural levels of the book, including full text. In 1995 - 1996, our first digitisation centre was built to process manuscripts and old printed books. Later, it was upgraded several times with additional devices such as scanners, book cradles for careful document fixation, sophisticated camera stands, microclimate control units, etc. Simultaneously, many software tools were developed to assist the digitisation production. The co-operation with the company became crucial for further development of this activity and both the library and the company grew thanks to each other. In 1999, another project started to output digital data: it was based on the idea of safeguarding acid-paper library materials through preservation microfilming combined with digitisation of microfilm for access purposes. In order to be able to store large amounts of image data produced by this second programme, a mass storage facility was plugged into the digitisation production line. It was based on robotic library using magnetic tapes as storage medium. Successively, the digitisation programmes began to be used also by other Czech institutions holding rare collections of documents: other libraries, museums, archives, and even castle libraries and church institutions. Today, from all the digitised documents almost half of them are from other institutions than the National Library. This is an important success that has taken place thanks to support of the Ministry of Culture through specific grant programmes. Interested institutions can ask the Ministry for up to 70% of the total digitisation cost for their projects with which they apply in calls for proposals.

QUIMaS (Queen's University Image Management System): a museum photographic database

This paper reports on the construction of an interactive image management system. The system's operation is improved by image processing techniques and parallel processing technology. Although image processing is largely a well understood problem, the technology for supporting it is still immature. Basically, it is a highly computationally intensive activity, and the purpose of our project was to address this very problem using parallel processing technology in the form of transputers. More specifically, we will describe the use of a transputer network in the development of an image database consisting of a collection of historical museum photographs. During the first phase of the project, we developed a prototype system consisting of a small number of photographs using a simple hardware configuration. It made use of the hard disk of the PC to store the photographs and was implemented using a single transputer. During the second phase, the full hardware configuration was implemented, including the building up of the database of around 1,000 photographs. The final system consists of an IBM-compatible PC equipped with the necessary image processing and mass storage facilities (650 Mb hard disk) and linked to a network of six transputers. The user interface is provided through a serial mouse and a keyword menu. Users are able to retrieve images in three different modes: (i) a predefined keyword list, which is arranged in a hierarchical fashion to select images relating to a particular subject or geographical area; (ii) the Browse mode allows the user to display a set of up to twelve photographs in miniature ‘stub’ format at one go (this is similar to the turning of the pages of an album). Individual items can then be selected and displayed in full size, if necessary; (iii) if the museum reference number is known, the user can type in the number to retrieve the relevant item. Section 1 will provide a brief review of the background to the project and the use of transputer technology in image processing. The selection and documentation of the photographs are described in Section 2. Section 3 describes the hardware and software configuration of the single-transputer-based prototype, and the full image database system implemented on a network of transputers. The organisation of the database, both textual and image data, is explained in Section 4. This is followed by a description of the processing techniques for image enhancement and compression, and a discussion of the results of both compression and decompression processes. The final section will discuss the menu-based, mouse-driven user interface, including the various search facilities and display modes used to view images from the database.

A distributed environment for run-time visualization and application steering in computational mechanics

The VASE software system for run-time visualization and interactive steering of high-performance computing applications is described. The system allows a user to specify interactively during the execution of a large-scale application which data structures are to be visualized and the format of the visualization. Tools are provided to develop and execute network-distributed applications that might involve remote supercomputers, graphics workstations and mass storage facilities. In addition to visualization functions, VASE supports interactive steering of large-scale computing applications. A debugger-like command interpreter allows the user to specify and execute steering operations during program execution. Steering can be used to adjust solution parameters, redefine problem data, control optimization procedures, etc. A distributed supercomputing application based on VASE for shape optimization of structures over variable topologies is presented.

Implementing Mass Storage Facilities in Operating Systems

The appearance in the commercial marketplace of online auxiliary memory devices with very large capacities has resulted in several new and interesting problems. These problems include new applications of the devices (generally called mass storage facilities or MSF's) for storage of on-line data, the need for new data structures organized about the physical characteristics of the MSF, problems in performance, enhancement of automatic device and data control, enhancement of automatic memory management systems, increased concern for data integrity, and the continuing need for more memory protection capability.

Use of a New Versatile Interactive Regression Analysis Program for X-Ray Fluorescence Analysis

XRF can be a powerful tool for quantitative elemental analysis-it can also be a big headache. The problem is, of course, that to perform a proper quantitative analysis one needs to first develop a good matrix correction model to convert the measured line intensities to concentrations. For empirical models, aside from the inherent difficulties in optimizing a set of interelement correction coefficients, the commercially available computer controlled spectrometers have in the past either provided rather poor regression analysis programs with their software or none at all. The reason for this has been the rather limited core size of the online computer and the lack of fast efficient mass storage facilities such as floppy disks.

Interactive X-ray laboratory automation utilizing multiuser basic

Automation of X-ray laboratory instruments has been achieved by combining commercially available automation hardware, X-ray units of various manufacturers, and a PDP-11 minicomputer. The automation provides simultaneous on-line control of up to ten separate X-ray instruments through user programs written in Lab-Basic which is the 1-8 User Basic software enlarged by the incorporation of three of additional capabilities, viz., routines to control automation hardware, commands making the programming easier, and mass-storage facility. The interactive nature of the hardware and of the software was dictated by the diverse types of analyses required in a general-purpose X-ray laboratory. The automation system provides the versatility needed for the various X-ray procedures by allowing the user to plan, debug, and execute the measurement, data reduction, and data presentation. Analytical procedures automated so far include the measurement of residual stress by X-ray diffraction, elemental analysis of catalysts by X-ray fluorescence, and quantitative phase analysis of ceramic catalyst support material by X-ray diffraction. Extension to other methods is contemplated.

APCOL: A programming system for computer-controlled psychology laboratories

The development of on-line computer systems can be facilitated by higher-level programming languages that are more powerful and easier to learn than machine-level Assembly languages. In general, it is not possible to speak ofa programming language without also describing the operating system and functional problem domain of the small computer system for which it is intended. This is because of the great variety in the architecture and configuration of small computers. However, it is possible to state more general requirements and design criteria for on-line computer languages in psychology. APCOL is an example of an integrated programming system. One of the important distinguishing features of the system is that it is implemented both on the small-scale laboratory computer and on a large general-purpose computer linked to the smaller machine via a high-speed communications network. This arrangement permits firsthand access to interactive program construction with immediate test of program function by using the on-line implementation as well as access to the text-editing and mass storage facilities of the large-scale machine.