On robustness of B-trees

A method is presented to detect index corruption and pointer corruption in B⁺-trees. The method uses the semantic information of indices and requires no extra pointers to be added to the data structure. Previous research on the robustness on B-trees has considered index corruption and pointer corruption separately and required extra pointers to be added to the data structure to achieve detectability, and correctability. The proposed method can detect and identify a single semantic or structural error     

A new range query algorithm for Universal B-trees

In multi-dimensional databases the essential tool for accessing data is the range query (or window query). In this paper we introduce a new algorithm of processing range query in universal B-tree (UB-tree), which is an index structure for searching in multi-dimensional databases. The new range query algorithm (called the DRU algorithm) works efficiently, even for processing high-dimensional databases. In particular, using the DRU algorithm many of the UB-tree inner nodes need not to be accessed. We explain the DRU algorithm using a simple geometric model, providing a clear insight into the problem. More specifically, the model exploits an interesting relation between the Z-curve and generalized quad-trees. We also present experimental results for the DRU algorithm implementation.     

Concurrency of operations on B-trees

Summary Concurrent operations on B-trees pose the problem of insuring that each operation can be carried out without interfering with other operations being performed simultaneously by other users. This problem can become critical if these structures are being used to support access paths, like indexes, to data base systems. In this case, serializing access to one of these indexes can create an unacceptable bottleneck for the entire system. Thus, there is a need for locking protocols that can assure integrity for each access while at the same time providing a maximum possible degree of concurrency. Another feature required from these protocols is that they be deadlock free, since the cost to resolve a deadlock may be high.Recently, there has been some questioning on whether B-tree structures can support concurrent operations. In this paper, we examine the problem of concurrent access to B-trees. We present a deadlock free solution which can be tuned to specific requirements. An analysis is presented which allows the selection of parameters so as to satisfy these requirements.The solution presented here uses simple locking protocols. Thus, we conclude that B-trees can be used advantageously in a multi-user environment.     

A dynamic software release model

The determination of optimal software release times constitutes an interesting decision making problem which involves the stochastic structure of the underlying software reliability model, as well as various cost parameters. There is an apparent tradeoff between testing the software further to improve its reliability, and releasing it for operational use to decrease the costs. We propose and analyze in depth a new dynamic model with sufficient generality. After each failure, a debugging activity, possibly imperfect, is undertaken and a decision is made regarding the duration of additional testing. If no failure is observed during this time, then the software is released. Otherwise, the failure is debugged and the decision process is repeated in a dynamic fashion. The problem is formulated using dynamic programming and interesting characterizations of the optimal release policy are presented. The dynamic solution procedure is demonstrated by some numerical illustrations.     

Time-delayed dynamic neural network-based model for hysteresis behavior of shape-memory alloys

Shape-memory alloys (SMAs) have received considerable amount of attentions for their engineering applications in recent years. The hysteresis in SMAs is sensitive to the state-varying tendency and frequency. Utilizing past information to estimate the hysteretic behavior gets increasing attention. In this paper, a time-delayed dynamic neural network (TDDNN) is proposed for modeling hysteresis of SMAs in online applications. By introducing a time delay between the input and output response, the TDDNN considers the time delay’s effect on the hysteresis. This proposed network was applied to a SMA wire actuator. Experimental results demonstrate the effectiveness of TDDNN. The identified results obtained by TDDNN are better than those obtained by dynamic neural network without considering the delay information. It demonstrates the importance of introducing the time delay. The different values of time delay item can also affect TDDNN’s identified results.     

Approximate storage utilisation of B-trees: A simple derivation and generalisations

A new, intuitive derivation of the approximate average storage utilisation of B-trees is presented, which is generalised to the analysis of B¹-trees whose average storage utilisation is found to be $\text{≈ 2 l}\text{n}\text{(}\text{3}\text{2}\text{)}$ or 81%. The approximate average storage utilisation of trees with arbitrary minimum fullness factor f(0 <f<1) is also obtained and found to be $\text{f11}\text{n}\text{(}\text{1}\text{f}\text{)}\text{(1?f)}$.     

A dynamic model of controlling invasive species

A dynamic model of controlling invasive weeds is first developed which is a large scale, nonlinear 0-1 integer programming problem. This model is then applied for the case of control of the invasive grass, Pennisetum ciliare (buffelgrass), in the Arizona desert. The large size of the problem makes the application of direct optimization methods impossible, instead the most frequently suggested strategies were analyzed and their consequences compared. The model is more advanced and complex than those examined in earlier studies.     

A dynamic model of a cement kiln

A cement kiln is a counter-flow type of process in which a complex series of exothermic and endothermic reactions take place. To understand its behavior and to provide a means of improving computer control, a dynamic partial differential model of the kiln has been developed. In this paper, the basic reactions and assumptions of the model will be discussed. A model of a coal/oil flame which takes into account the surrounding temperatures is developed. The dynamic behavior of the kiln as exhibited by this model is then indicated. In particular, it is shown that the interaction between the two exothermic reactions causes the kiln to be basically unstable with respect to regulating the position of the burning zone.     

A neuromodulation model of behavior selection in the fighting behavior of male crickets

The results of neurophysiological research have indicated the important role of neuromodulation in behavior decisions during fighting between male crickets. To understand such a dynamic behavior generation mechanism, we attempt to construct a neuromodulation model of behavior selection for the fighting behavior of a cricket. In this paper, we propose a dynamic system model of neuromodulation with the efficacy based on neurophysiological knowledge, facts, and hypotheses from the viewpoint of synthesis. The efficacy of the sensory processing center is introduced to our previous model and its dynamics is influenced by the frequency of the interactions with the other cricket. Utilizing an extended neuromodulation model, computer simulations related to a multiple-individual environment were carried out, and the results are discussed. In particular, the properties related to the standard deviation of the value of octopamine in several population density cases are discussed.     

Specifying the dynamic behavior of management systems

Decision making in any complex system is a very difficult task. In Man, decisions are reached as a result of trying to satisfy both conscious and unconscious goals. To emulate this in a computer system we need to find a way of representing goals and modeling the decision making process. This paper describes a model for decision making in the context of the management of distributed computer systems, and discusses the implications for the representation of goals and other information used during the decision making process. The work described in this paper was performed in the ESPRIT II project DOMAINS. This project is concerned with developing an architecture for the integrated management of all resources in a networked system. The emphasis of this paper lies in modeling rather than implementation.     

Modeling the dynamic behavior of hypermedia applications

Hypermedia applications can be defined as collections of interactive and multimedia documents that are organized as a hypertext net. The development of hypermedia applications poses specific problems, such as the need for modeling sophisticated navigational structures, interactive behaviors, and harmonic presentations involving the synchronization of contents. Moreover, the increasing popularity of Internet based systems has put stress on the lack of mechanisms to formally specify security policies when designing hypermedia applications. Traditional design models and methodologies are not suitable for hypermedia applications and the up-to-now developed hypermedia oriented models do not cover the whole set of design needs. In this context, we present Labyrinth, a hypermedia oriented model providing formal elements to describe the static structure and dynamic behavior of this kind of nonlinear, multisensory, and interactive applications     

A dynamic model for the optimal selection of secondary indexes

A model is presented which determines the optimal degree of secondary indexing for data processing requirements which follow variations over different time periods in a manner known in advance. The paper proves a number of properties which characterize the model and develops an algorithm which greatly reduces the solution space to be searched. The algorithm uses dynamic programming techniques and it may be used by Database Administrators to determine the time at which the entering and dropping of secondary indexes to and from the database should take place.     

A finite capacity dynamic priority queuing model

A single server queueing model with two types of arrivals is discussed under the assumptions of Poisson arrivals, (possibly different) general services and finite waiting room for each type of customer. Under a dynamic non-preemptive priority service rule, the steady state analysis of the model is performed. A number of interesting and intuitive results are obtained. In the case when the services are of phase type, implementable algorithms are developed for computing various system performance measures. The recursive computational schemes can be used interactively in the design of such queuing systems. A number of numerical examples are discussed.     

A dynamic data model for mobile GIS

A fast response time is a major objective for Mobile Geographic Information System (GIS) applications. This study provides a solution for improving the performance of response time by a dynamic data model. A conceptual dynamic data model is proposed, which covers (a) “position” information of selected geographic objects relevant to the GIS user's interest within his current location, (b) the selected attribute information in which the mobile GIS user is interested. In this approach, first, the attribute information is selected through a validating process making use of the temporal and attribute filters. Second, a specially designed dynamic database is employed to enable the implementation of the conceptual dynamic data model. This dynamic database is continually updated in accordance with the spatial, temporal and attribute constraints specified for the conceptual model. This design of a dynamic data model increases the availability of spatial data to mobile GIS users by providing up to date accurate information relevant to the area of interest, in a limited communication bandwidth. Third, an experimental study has been conducted and the results demonstrate that by using a dynamic database the response time can be reduced to one-third of that of a conventional database. The response time performance can be further improved as the size of the database is increased.     

A model for dynamic strategic vendor selection

Once the decision to outsource has been made, outsourcing vendors supplying the product or service have to be selected. This paper focuses on dynamic strategic vendor selection. Existing approaches supporting vendor selection neglect the interdependencies in time arising from investment costs of selecting a new vendor and costs of switching from an existing vendor to a new one. These shortcomings of current approaches motivate the research presented in this paper. A dynamic decision making approach for strategic vendor selection based on the principles of hierarchical planning will be proposed.     

A bionic model of adaptive searching behavior

The adaptive behavior line of investigation, which is considered as a bionic approach to development of systems of artificial intelligence, is characterized. One of the topical problems in the framework of this approach is the simulation of searching animal behavior. A general scheme of searching adaptive behavior with inertial switching between search tactics is presented. A particular model of searching behavior of larvae of caddis flies building a case-house from particles of different size and searching for gathering of suitable particles is investigated. The adequacy of the model to biological experimental data is shown, which is characterized by its specificity reflecting the memory data of larvae about both the sizes of last-processed particles and the general properties of the inertial switching.     

A model of dynamic separation for transactional memory

Dynamic separation is a new programming discipline for systems with transactional memory. We study it formally in the setting of a small calculus with transactions. We provide a precise formulation of dynamic separation and compare it with other programming disciplines. Furthermore, exploiting dynamic separation, we investigate some possible implementations of the calculus and we establish their correctness.     

A weighted intrusion detection model of dynamic selection

In view of the difficulty of existing intrusion detection methods in dealing with new forms, large scale, and high concealment of network intrusion behaviors, this paper presents a weighted intrusion detection model of the dynamic selection (WIDMoDS) based on data features. The aim is to customize intrusion detection models for network intrusion data sets of different types, sizes and structures. First, according to data features, single classifiers are clustered using a hierarchical clustering algorithm based on the classifiers evaluation indicators, and then, the classifiers selection is by means of accuracy of the single classifiers, in addition, the data-classifier applicable indicators (DCAI) and of the classifiers performances are used for calculating the weights of subjective and objective, and then calculating combined weight ranks. Finally, a custom intrusion detection model is generated by the Weight-voting (W-voting) algorithm. Our experiments show that this model can optimize the number of classifiers based on the data sets features, reduce the problem of redundant or insufficient classifiers in the ensemble process. A new network intrusion detection model of combining the classifier characteristics with the dataset attributes can improve the accuracy of intrusion detection.