Conventional File Research Articles

Design and implementation of a video network server

In this article, we propose a new video server method, which is an extension of an existing network file system to include video functions. Conventional network file systems cannot transfer video data in real time, because they do not have a mechanism to guarantee the video data transfer rate. Therefore, we use a new time slot method that combines the divided time slot method and the elevator seek method. Furthermore, we use a new method for sending video data from the server to the network. It performs rate control on existing network protocols that do not have rate control functionality. The result of implementation of these methods shows that the new time slot method decreases client response time to one-half to one-tenth compared with conventional methods, and we confirmed that the worst response delay by the new rate control method is within the permissible time that guarantees data transfer rate. We decreased response time for clients in our new video server method, by employing the time slot method to guarantee video data read-bit-rate from disks, we employ the time slot method to guarantee the bit rate in reading video data from disks, and we decreased the response time for clients (by using the time slot method in reading from disks).

Horizontally divided signature files on a parallel machine architecture

The signature file method has widely been advocated as an efficient index scheme to handle new applications demanding a large amount of textual databases. Moreover, it has been recently extended to support multimedia unformatted data. These multimedia data must be rapidly managed for synchronization and presentation, for which parallel database computers have been proposed. In order to achieve good performance, the signature file approach has been required to support parallel database processing. Therefore, in this paper we propose a horizontally divided parallel signature file method (HPSF) using extendible hashing and frame-slicing techniques. In addition, we propose a heuristic processor allocation method so that we may assign signatures into the given number of processors in a uniform way. To show the efficiency of HPSF, we evaluate the performance of HPSF in terms of retrieval time, storage overhead, and insertion time. Finally, we show from the performance results that HPSF outperforms the conventional parallel signature file methods on retrieval performance as well as a dynamic operating measure to combine both retrieval and insertion time.

Comparison of debris extruded apically in straight canals: Conventional filing versus profile .04 Taper series 29

The purposes of this study were to determine quantitatively the amount of debris and irrigant forced in an apical direction, the frequency of apical plug development, and the time required to prepare canals when a step-back technique using K-files was compared with the .04 Taper system. Sixty-nine extracted teeth with straight canals were divided into four statistically similar groups. Two groups were instrumented either 1 mm short of the apical foramen or to the apical foramen with K-files. The other two groups were instrumented to the same levels using .04 Taper files. The extruded debris and irrigant were collected in preweighed vials. The weight of the debris and volume of irrigant extruded using both techniques were compared and analyzed using paired t test and one-way ANOVA. Tukey's Multiple Comparisons Procedure showed K-files used to the apical foramen extruded significantly more debris than the other three groups (p < 0.01). The .04 Taper files used 1 mm short extruded less debris than the other groups. Significantly more irrigant was extruded when filing was performed to the apical foramen (p < 0.007), regardless of the technique used. More apical plugs were created in teeth filed short of the apical foramen, but the difference between the two preparation techniques was not statistically significant. It took significantly less time to instrument canals with the .04 Taper system than with K-files (p < 0.002).

Design and implementation of a video network server

In this article, we propose a new video server method, which is an extension of an existing network file system to include video functions. Conventional network file systems cannot transfer video data in real time, because they do not have a mechanism to guarantee the video data transfer rate. Therefore, we use a new time slot method that combines the divided time slot method and the elevator seek method. Furthermore, we use a new method for sending video data from the server to the network. It performs rate control on existing network protocols that do not have rate control functionality. The result of implementation of these methods shows that the new time slot method decreases client response time to one-half to one-tenth compared with conventional methods, and we confirmed that the worst response delay by the new rate control method is within the permissible time that guarantees data transfer rate. We decreased response time for clients in our new video server method, by employing the time slot method to guarantee video data read-bit-rate from disks, we employ the time slot method to guarantee the bit rate in reading video data from disks, and we decreased the response time for clients (by using the time slot method in reading from disks).

The Effect of Disk Roughness on the Wear of Contact Recording Heads

In conventional disk files, the slider is supported by an air-bearing when the disk is rotating at its designed speed. With the continued reduction of magnetic spacing in order to increase the areal density, a natural extension of the traditional recording system is contact recording. We investigate the wear of the contact recording head designed for such a class of rigid magnetic disk files where the read/write element carrying slider is intended to remain in continuous contact during every phase of the disk drive operation. In particular, we study the effect of disk roughness and load on the wear rate of the recording head. It is observed that the wear rate is proportional to initial interfacial load, however the observation cannot be extrapolated beyond the loads studied in the paper. The experimental observations agree well with expectations for a system where an abrasive wear model applies. We also show that the wear rate is predominantly governed by the existence of isolated asperities that lie well outside of three standard deviations of the disk surface roughness.

OR 24 Evaluation of rotary NiTi systems and conventional filing: degree of apical extrusion: S.D. Shoha* and G.N. Glickman The University of Michigan, Ann Arbor

OR 24 Evaluation of rotary NiTi systems and conventional filing: degree of apical extrusion: S.D. Shoha* and G.N. Glickman The University of Michigan, Ann Arbor

Client/Server computing: is this the future direction for the clinical laboratory?

One of the major trends in computing for the 1990s is the move towards distributed systems based on a Client/Server architecture. Although a recent survey has suggested that some 41% of the major companies in the UK are either using or planning to adopt this new technology, there is little evidence at present of similar progress in the field of clinical laboratory computing. The Pathology laboratories at St. Luke's Hospital have been developing in-house computer systems using object-oriented software tools since 1988, but these were initially based on conventional file sharing and suffered from poor performance under load. The conversion to Client/Server took place in March 1993 and the results have either met or exceeded all expectations. Our experience suggests that this approach may well be the way forward for the high performance but user-friendly laboratory systems of the future.

PR 22 Comparison of debris extruded apically: Conventional filing versus profile .04 taper series 29: T Beeson*, G Hartwell. Medical College of Virginia, Richmond, VA

PR 22 Comparison of debris extruded apically: Conventional filing versus profile .04 taper series 29: T Beeson*, G Hartwell. Medical College of Virginia, Richmond, VA

Continuous display of presentations sharing clips

Databases were introduced to remove redundancy from conventional file systems and encouragesharing, which resulted in update anomalies when information was modified. With presentations (movies) sharing clips (sequence of frames), continuous display becomes challenging as well. Continuous display requires the system to retrieve the information with no disruptions or delays (hiccups) once a display is initiated. To ensure a continuous display using a multi-disk hardware platform, a video object is striped into subobjects. The system enforces a regular schedule on retrieval of each subobject by controlling the placement of the subobjects across the disks. Now if different presentations share subobjects, each presentation will enforce its own restrictions on the placement of the data, resulting in an irregular schedule. We investigate approaches to render a schedule regular for two alternative display paradigms: Demand and Data driven.

Transportation of curved canals prepared with canal master U, canal master U niti, and stainless steel K-type files

The purpose of this study was to evaluate and to compare root canal configuration after preparation with three different hand instruments and techniques: the canal master U preparation technique (Brasseler, Savannah, GA.), using stainless steel or nickel-titanium canal master U instruments, and the step-back technique using precurved conventional stainless steel K-type files. Sixty-three simulated curved canals were divided in three groups of 21 each. Each group was prepared using one of the three instruments. Comparison of root canal configuration was evaluated with pre- and postoperative photographs that measured the difference in canal diameter and the mesial and distal transportation of the canal walls at the canal length and at levels 1, 2, 3, 4, 5, 6, 7, and 8 mm coronal to the canal length. Data obtained were analyzed statistically using an analysis of variance. Instrument breakage was also recorded. Results showed that the final diameter of the prepared canals as well as canal transportation were significantly different between both canal master U instruments and the stainless steel K file. Three stainless steel canal master U instruments separated during instrumentation whereas none in the nickel-titanium canal master U and stainless steel K-type file groups separated. The results of this study show that the canal master U instruments and technique provide a better canal configuration than K files using the step-back technique and that the nickel-titanium canal master U and stainless steel K-type file offers a greater safety factor against breakage than the stainless steel canal master U.

Optimizing Unix database file operations

Ratfiles (RATional FILE System) by-passes the Unix kernel to perform database-file operations at nearly twice the speed of conventional file systems and offers several techniques, including atomic write and write-order discipline, to improve data integrity. >

Performance and traffic analysis of a network-based distributed system

In this paper we study the performance of a distributed computing system that consists of a number of clients and a server, interconnected by a carrier-sense multiple-access with collision detection (CSMA/CD) LAN. Each client represents a single-user discless workstation, or an intelligent terminal, and generates application workload using either a conventional Unix file system or the Network File System (NFS). To characterize the application workload we perform a series of measurement experiments in a controlled environment. During each experiment the traffic on the network, and the activity on the various system resources are monitored. The measurements obtained from the experiments are used to parameterize a queueing network model of the system, which is then used to project the performance of the system under various load conditions, to identify system bottlenecks, and to compare design alternatives. The results obtained from the queueing network analysis are used to determine the maximum number of clients that can be supported by the system without violating system performance requirements.

Federated database management system: Requirements, issues and solutions

The use of database management systems (DBMS) to replace conventional file processing systems has dramatically increased in the past years. Although the use of DBMSs overcomes many of the limitations of file processing systems, many important applications require access to and integration of information among several and often incompatible DBMSs. In this paper we discuss an approach, known as the federated database approach, that allows users and applications to access and manipulate data across several heterogeneous databases while maintaining their autonomy. We discuss the requirements and objectives of a federated database management system, and outline the major issues and challenges for building and using such a system. In particular, we address the design issues from three angles: transaction management, system architecture, and schema integration. Also, we present a five-step integration methodology followed by a comprehensive example to illustrate the concepts and techniques involved in this integration methodology.

A comparison of weights of debris extruded apically by conventional filing and canal master techniques

Sixty extracted human teeth were divided into three groups of 20 each. Apically extruded debris and irrigant were collected, dried, and weighed by the following three instrumentation techniques: (a) group 1, filing 1 mm short of the foramen; (b) group 2, Canal Master instrumentation to the foramen; and (c) group 3, filing to the foramen (for a relative comparison). The results indicated that all three groups were significantly different from one another. Group 1 had the least amount of debris extruded. Of the two groups instrumented to the foramen, group 3 had twice as much debris extruded as group 2. An apical dentinal plug was frequently found in group 1 and was probably a major reason why this group had the least amount of extruded debris. The significance of this dentinal plug and possible indications for instrumentation to the foramen are discussed.

Machining efficiency of Flex-R, K-Flex, Trio-Cut, and S files

Many root canal instruments with several different designs have been introduced during recent years. This article evaluates the machining properties of four such instruments: the Flex-R, K-Flex, Trio-Cut, and S file. There are large variations in the machining properties of these instruments. The results are comparable to findings when evaluating conventional root canal files which show that the Hedstrom file is much more efficient when considering removal of material than the K file. The Flex-R file, K-Flex file, and Trio-Cut file are similar in design. The two former brands perform in a similar fashion, while the Trio-Cut file is less efficient than any of the evaluated K files. The S file performs as a Hedstrom file which can be expected from its similarity in design to that instrument.

Need for “flexibility” in a conceptual model

The translation of one data model into another has become necessary. Database design methodologies stipulate that a conceptual model should be created prior to implementing a new database system. It is then, usually, the translation of this conceptual model into the physical model of a commercial database management system (DBMS) that is a necessity (e.g., The translation of the entity-relationship model into a relational DBMS). However, more and more we are seeing the translation of the data models in currently implemented conventional file and database systems into conceptual models (e.g., The translation of an ORACLE DBMS into an entity-relationship model). It is the conceptual model that is produced from the ‘reverse’ translation process that we address here; however, the ideas of flexibility can be applied to new database designs also. Since several different reverse translation algorithms have been developed, the questions that arise are: How do we know the resulting conceptual models are accurate? Does the resulting model contain enough information to be useful to database designers and which one is easier for the database designer to work with and to use as a communication tool with users or to develop new databases? The problem is that resulting conceptual data models from two different algorithms may differ even in the data objects obtained, and yet both be equivalent to the original model.

An integrated toolset for engineering software configurations

Configuration management in toolkit oriented software development environments (SDE), such as the UNIX system, is a long standing nuisance. Mostly, one has to face the choice between poorly or not at all integrated, independent tools, or highly integrated, most specialized, and often language dependent environments. The first choice offers very limited support for a complex task that needs a broad informational basis. The second choice often takes away the programmers' most cherished tools, forces him to adopt some different work discipline, and thereby eventually restricts his creativity. The toolset described in this paper integrates a dedicated version control system and shape, a significantly enhanced Make [Feld79a] program, on the basis of a common object model. This object model comprises multiple versions of software objects as well as conventional file system objects. Taking this approach made it possible to have a sufficiently integrated toolsystem for engineering software configurations while retaining the flexibility of the basic toolbox philosophy, permitting the use of 'off-the-shelf' tools, e.g. editors or compilers.

An integrated toolset for engineering software configurations

Configuration management in toolkit oriented software development environments (SDE), such as the UNIX system, is a long standing nuisance. Mostly, one has to face the choice between poorly or not at all integrated, independent tools, or highly integrated, most specialized, and often language dependent environments. The first choice offers very limited support for a complex task that needs a broad informational basis. The second choice often takes away the programmers' most cherished tools, forces him to adopt some different work discipline, and thereby eventually restricts his creativity. The toolset described in this paper integrates a dedicated version control system and shape, a significantly enhanced Make [Feld79a] program, on the basis of a common object model. This object model comprises multiple versions of software objects as well as conventional file system objects. Taking this approach made it possible to have a sufficiently integrated toolsystem for engineering software configurations while retaining the flexibility of the basic toolbox philosophy, permitting the use of 'off-the-shelf' tools, e.g. editors or compilers.

A group-select operation for relational algebra and implications for database machine design

A group-select operation has been defined for relational algebra. This operation is found to be useful for efficiently reducing expressions of nonprocedural relational languages that permit natural quantifiers. Conceptually, the operation first partitions a relation into blocks of tuples that have the same value for an attribute or attribute concatenation. It then extracts each block for which a specified number of tuples meet a specified condition. The quantity of tuples for the operation is specified by means of a natural quantifier. Performance of the group-select operation will be poor with conventional file processing, making the operation more suitable for use with a database machine with an associative memory. >

Log files: an extended file service exploiting write-once storage

A log service provides efficient storage and retrieval of data that is written sequentially (append-only) and not subsequently modified. Application programs and subsystems use log services for recovery, to record security audit trails, and for performance monitoring. Ideally, a log service should accommodate very large, long-lived logs, and provide efficient retrieval and low space overhead. In this paper, we describe the design and implementation of the Clio log service. Clio provides the abstraction of log files : readable, append-only files that are accessed in the same way as conventional files. The underlying storage medium is required only to be append-only; more general types of write access are not necessary. We show how log files can be implemented efficiently and robustly on top of such storage media—in particular, write-once optical disk. In addition, we describe a general application software storage architecture that makes use of log files. This work was supported in part by the Defense Advanced Research Projects Agency under contracts N00039-84-C-0211 and N00039-86-K-0431, by National Science Foundation grant DCR-83-52048, and by Digital Equipment Corporation, Bell-Northern Research and AT&amp;T Information Systems.