Recursive Research Articles

The Recursive Nature of Positivity

The Recursive Nature of Positivity

Productivity of stream definitions

We give an algorithm for deciding productivity of a large and natural class of recursive stream definitions. A stream definition is called 'productive' if it can be evaluated continually in such a ...

A Study on the Pitch Search Time Reduction of G.723.1 Vocoder by Improved Hybrid Domain Cross-correlation

In this paper we proposed a new algorithm that can reduce the open-loop pitch estimation time of G.723.1. The time domain cross-correlation method is simple but has long processing time by recursive multiplication. For reduction of processing time, we use the method that compute the cross-correlation by multiplying the Fourier value of speech by it's complex conjugate. Also, we can reduce the processing time by omitting the bit-reversing of FFT and IFFT for time-frequency domain transform. As a result, the processing time of improved hybrid domain cross-correlation algorithm is reduced by 67.37% of conventional time domain cross-correlation.

A Speech Enhancement Algorithm based on Human Psychoacoustic Property

In the speech system, for example hearing aid as well as speech communication, speech quality is degraded by environmental noise. In this study, to enhance the speech quality which is degraded by environmental speech, we proposed an algorithm to reduce the noise and reinforce the speech. The minima controlled recursive averaging (MCRA) algorithm is used to estimate the noise spectrum and spectral weighting factor is used to reduce the noise. And partial masking effect which is one of the human hearing properties is introduced to reinforce the speech. Then we compared the waveform, spectrogram, Perceptual Evaluation of Speech Quality (PESQ) and segmental Signal to Noise Ratio (segSNR) between original speech, noisy speech, noise reduced speech and enhanced speech by proposed method. As a result, enhanced speech by proposed method is reinforced in high frequency which is degraded by noise, and PESQ, segSNR is enhanced. It means that the speech quality is enhanced.

Fast Approximate kNN Graph Construction for High Dimensional Data via Recursive Lanczos Bisection

Nearest neighbor graphs are widely used in data mining and machine learning. A brute-force method to compute the exact kNN graph takes Θ(dn2) time for n data points in the d dimensional Euclidean s...

Recursive Selection Method for False Report Filtering

In wireless sensor networks, adversaries can compromise sensor nodes and use them to inject forged reports, which can lead to false alarms and energy depletion. Recently, several research solutions have been proposed to detect and drop such forged reports during the forwarding process. Since each solution has its own energy consumption characteristics, employing only a single filtering solution for a network is not a recommended strategy, in terms of energy savings. This paper proposes a new scheme, for the current network status, which is much more suitable than the other filtering schemes available (SEF, IHA and KIF). For this, a fuzzy rule-based system has been applied for the evaluation. The major parameters for the evaluation have been selected as follows: the distance from the base station, false traffic ratio, thresholds, and detection capability of SEF. For recursive selection, four input parameters and the filtering method that is selected in the first step are considered in detail. The effectiveness of the proposed method is shown by the simulation results described in the final part of the paper.

Moments of the queue size distribution in the MAP/G/1 retrial queue

We consider an MAP/G/1 retrial queue. A necessary and sufficient condition is obtained for the existence of the moments of the queue size distribution. The condition is expressed in terms of the moment condition for a service time distribution. In addition, we provide recursive formulas for the moments of the queue size distribution. Numerical examples are given to illustrate our results.

Recursive Interpellation: Digitally Recoding Althusser

Recursive Interpellation: Digitally Recoding Althusser

ON A DIFFERENCE EQUATION MOTIVATED BY A HEAT CONDUCTION PROBLEM

Let $\{ \tau_n \}$ be a sequence of numbers recursively defined by $$ f(\tau_n) + f(\tau_n+\tau_{n-1}) + \dots + f( \tau_n+\tau_{n-1} + \dots +\tau_1 ) =1 , $$ where $f$ is a continuous and strictly decreasing function on $(0,\infty) $ with $f(0^+) \ge 1, $ and $ f(\infty)=0 .$ Assume the convexity of $\log f$ or $\log |f'|$. It can be shown that $ \{ \tau_n \} $ is increasing. Thus $ \lim \tau_n $ exists in $ (0, \infty]$. \par The difference equation above is motivated by a heat conduction problem studied in Myshkis (1997) and Chen, Chow and Hsieh (2006).

Review of the Nonlinear Filters in the Land Data Assimilation

The land data assimilation research has become the emerging domain in the geoscience,the data assimilation algorithm obtained rapid development and widespread application taking the nonlinear filter as representative's.The extended Kalman filter,unscented Kalman filter,the ensemble Kalman filter and the SIR particle filter are discussed in the Bayesian theory framework from the viewpoint of the recursive Bayesian estimation.Towards the problems in the application of the ensemble Kalman filter and the SIR particle filter,some techniques that can improve the filter performances are also reviewed,such as the covariance localization,the covariance inflation,the double ensemble Kalman filter,the perturbations in the ensembles,the model forcing and parameters,the ensemble square root Kalman filter and the improved variants of the particle filters.The advantages and disadvantages of each filter as well as the applied perspective and the future research directions are discussed.

A Formal Model of ODS Schema in LIPS

LIPS (Library Information Processing System) which I have proposed during the study for my research. A library system contains books, authors, and users and many types of other materials. The Location in identified for books by a Class Number, authors by authors name, and user by a user name. To execute a query on any of these components the Management Software needs accumulated expression, formulae and rules. Therefore, semantics of an Object Oriented Database System schema greatly depends on the model theory of accumulated expression calculus. Moreover, an ODS schema involves recursive specification. Recursion arises with recursive rules as well as with recursive message definition. In order to uniquely define the semantics of such a schema the structure of models plays an important role. It has been shown during this discussion that for a restricted class of schema, the semantics can be uniquely specified. The intention of this article is to highlight the finding during our study on LIPS regarding the used expression, formulae and rules in the ODS schema. The approach used here is the least fixed-point approach of specification of semantics. In the following discussion we exclude formulae, which involves negation. Unless explicitly mentioned a formula is assumed to be free of negation. The utility of different features of algebra will be clear in subsequent sections when the tools developed here are used in describing the semantics for query processing.

Simulation Subsumption or Déjà vu on the Web

Simulation unification is a special kind of unification adapted to retrieving semi-structured data on the Web. This article introduces simulation subsumption, or containment, that is, query subsumption under simulation unification. Simulation subsumption is crucial in general for query optimization, in particular for optimizing pattern-based search engines, and for the termination of recursive rule-based web languages such as the XML and RDF query language Xcerpt. This paper first motivates and formalizes simulation subsumption. Then, it establishes decidability of simulation subsumption for advanced query patterns featuring descendant constructs, regular expressions, negative subterms (or subterm exclusions), and multiple variable occurrences. Finally, we show that subsumption between two query terms can be decided in O(n!n) where n is the sum of the sizes of both query terms.

Tensor Product Formulation for Hilbert Space-Filling Curves

We present a tensor product formulation for Hilbert space-filling curves. Both recursive and iterative formulas are expressed in the paper. We view a Hilbert space-filling curve as a permutation which maps two-dimensional 2(superscript n)×2(superscript n) data elements stored in the row major or column major order to the order of traversing a Hilbert curve. The tensor product formula of Hilbert space-filling curves uses several permutation operations: stride permutation, radix-2 Gray permutation, transposition, and anti-diagonal transposition. The iterative tensor product formula can be manipulated to obtain the inverse Hilbert permutation. Also, the formulas are directly translated into computer programs which can be used in various applications including image processing, VLSI component layout, and R-tree indexing, etc.

Taming Existence in RDF Querying

We introduce the recursive, rule-based RDF query language RDFLog. RDFLog extends previous RDF query languages by arbitrary quantifier alternation: blank nodes may occur in the scope of all, some, or none of the universal variables of a rule. In addition RDFLog is aware of important RDF features such as the distinction between blank nodes, literals and URIs or the RDFS vocabulary. The semantics of RDFLog is closed (every answer is an RDF graph), but lifts RDF’s restrictions on literal and blank node occurrences for intermediary data. We show how to define a sound and complete operational semantics that can be implemented using existing logic programming techniques. Using RDFLog we classify previous approaches to RDF querying along their support for blank node construction and show equivalence between languages with full quantifier alternation and languages with only ∀∃ rules.

Teaching and viewing recursion as delegation

We present an effective way to teach recursion which we believe nearly anyone can understand. Most people are familiar with the concept of someone delegating a task to another person. Our method is...

Adding Recursion to Graph Transformation

In this paper we define recursive rules in the double pushout approach (DPO) to graph transformation. Classical DPO rules are extended with a base case condition and a recursion condition. Mechanisms are provided to pass the match from both conditions to the rule's left hand side, and also between two consecutive steps in the recursion. The approach is useful when recursive structures (such as inheritance hierarchies, nested component hierarchies, networks of functional blocks, etc.) have to be processed. Although we present the recursion for DPO, it can also be adapted to other approaches to graph and model transformation. We present examples for model transformation, model simulation and model optimization in different application domains.

Profiles of random trees: Plane-oriented recursive trees

We derive several limit results for the profile of random plane-oriented recursive trees. These include the limit distribution of the normalized profile, asymptotic bimodality of the variance, asym...

Nonlinear formulation for flexible multibody system with large deformation

In this paper, nonlinear modeling for flexible multibody system with large deformation is investigated. Absolute nodal coordinates are employed to describe the displacement, and variational motion equations of a flexible body are derived on the basis of geometric nonlinear theory, in which both the shear strain and the transverse normal strain are taken into account. By separating the inner and the boundary nodal coordinates, the motion equations of a flexible multibody system are assembled. The advantage of such formulation is that the constraint equations and the forward recursive equations become linear because the absolute nodal coordinates are used. A spatial double pendulum connected to the ground with a spherical joint is simulated to investigate the dynamic performance of flexible beams with large deformation. Finally, the resultant constant total energy validates the present formulation.

The Disposition Effect in Open-end Mutual Fund Market: A Study of Taiwan Equity Funds

This paper uses a unique data set with complete information of purchase and redemptions of individuals and institutions in the Taiwan open-end equity mutual fund market. We employ the recursive ordinary least square model in variable to identify the determinants of purchasing and redemption activities over a 56-month period. Our results show that investors in Taiwan have two types of disposition effect. First, we find that investors are not to redeem the funds with past negative capital return, which we call it ”insignificant redemption disposition effect”. Second, we find investors are significantly less willing to flee from past extremely negative excess returns, but the unwilling to redeem the funds with moderate negative excess return is not significant. We call that ”less willing redemption disposition effect”.

A note on recursive multiple-priors

This note fills a gap in the proof of recursive multiple-priors utility [L. Epstein, M. Schneider, Recursive multiple priors, J. Econ. Theory 113 (2003) 1–31].