Cancellation Problem Research Articles

A cancellation theorem for generalized Swan modules

The module cancellation problem asks whether, given modules X, X′ and Y over a ring Λ, the existence of an isomorphism X⊕Y≅X′⊕Y implies that X≅X′. When Λ is the integral group ring of a metacyclic group G(p,q), results of Klingler show that the answer to this question is generally negative. By contrast, in this case we show that cancellation holds when Y=Λ and X is a generalized Swan module.

A new adaptive solution based on joint acoustic noise and echo cancellation for hands-free systems

In this paper, we address the problem of joint acoustic noise and echo cancellations for hands-free systems. The problem of acoustic echo cancelation (AEC) in the presence of background noise is a real challenge for any actual system. In this paper, we propose a new system that combines both processes, i.e. ANC and AEC. In our approach, we propose a two-stages procedure as follows: in the first stage, we propose to use the forward blind source separation (FBSS) structure to cancel the background noise components that is superimposed to the acoustic echo signal in the same environment, this FBSS structure uses the two-channel normalized least mean square (TC-NLMS) adaptive algorithm to cancel the background noise from the primary signal. In the second step, we propose to use an AEC system based on a single channel NLMS (SC-NLMS) algorithm to efficiently suppress the acoustic echo signal. This new combination between the FBSS and the AEC system allows reducing the acoustic echo signal to lower mean square values (MSE) in the permanent regime, this behavior will not be possible without FBSS. The performance properties of the proposed algorithm in such environment (i.e. presence of background plus acoustic echo signals in the same time) is evaluated with competitive algorithm with various objective criteria (ERLE, SegSNR, and GainMSE).

Reciprocal-Filter-Based STAP for Passive Radar on Moving Platforms

This paper addresses the problem of clutter cancellation and slowly moving target detection in digital video broadcast-terrestrial-based passive radar systems mounted on moving platforms. First, we show that conventional processing approaches based on the availability of multiple receiving channels might be ineffective in the considered scenarios due to the impossibility to control the employed waveform of opportunity. Therefore, an appropriate space-time adaptive processing scheme is proposed to cope with the Doppler spread clutter returns aiming at ground moving target indication applications. It exploits the benefits of the reciprocal filtering strategy applied at a range compression stage together with a flexible displaced phase center antenna approach. The effectiveness of the proposed scheme is demonstrated via application to a simulated dataset and then tested against experimental data collected by multichannel passive radar on a maritime moving platform.

Multi-CRC Polar Codes and M-SCFlip-Based Decoding

A multi-cyclic redundancy check (Multi-CRC) polar code construction algorithm is proposed in this paper to solve the error propagation problem of successive cancellation decoding for polar codes. In this algorithm, the information sequence is optimized into several segments to allow decoding errors to be corrected in time, minimizing the impact of error propagation. An improved multi-successive cancellation bit flipping (M-SCFlip) decoding algorithm is proposed to execute the bit flipping operation after CRC check-in each segment. In the low-SNR region, the proposed new multi-CRC polar code with successive cancellation list (SCL) decoding has a slight frame-error rate (FER) degradation compared with the original CRC polar code. With the M-SCFlip decoding algorithm developed in this paper, it achieves a better FER performance compared with the CRC polar code with successive cancellation (SC) and SCL ( $L\!=\!2$ ) decoding algorithms. In addition, it has a lower decoding delay and requires a lower memory space. For example, at a FER of 10−4 with the same code length and effective code rate, the proposed multi-CRC polar code with M-CFlip decoding achieves a 1.19 dB and 0.79 dB gains over existing CRC polar codes with the SC and SCL ( $L\!=\!2$ ) decoding algorithms, respectively.

Pullback scheme implementation in ORB5

The pullback scheme is implemented in the global gyrokinetic particle-in-cell code ORB5 (Jolliet et al., 2007[1]) to mitigate the cancellation problem in electromagnetic simulations. The equations and the discretisation used by the code are described. Numerical simulations of the Toroidal Alfvén Eigenmodes are performed in linear and nonlinear regimes to verify the scheme. A considerable improvement in the code efficiency is observed. For the internal kink mode, it is shown that the pullback mitigation efficiently cures a numerical instability which would make the simulation more costly otherwise.

A new adaptive filtering algorithm for stereophonic acoustic echo cancellation

This paper addresses the stereophonic acoustic echo cancelation (SAEC) problem in teleconferencing system by adaptive filtering algorithm. We propose a new stereophonic version of the fast normalized least mean square (FNLMS) algorithm. The proposed algorithm is an extended version of the FNLMS algorithm to the stereophonic case with important improvement of the prediction part that becomes stable in the stereophonic case. The basic idea behind the proposed stereophonic fast normalized least mean square (SFNLMS) algorithm is the normalization of the predictor parameter by the inputs variance for each channel. Simulation results of a comparison between the proposed SFNLMS algorithm and the classical SNLMS version in term of convergence speed and stability are presented.

Evaluation of relativistic transport coefficients and the generalized Spitzer function in devices with 3D geometry and finite collisionality

The relativistic generalization of the linearized drift kinetic equation solver NEO-2 is presented which is used for computation of neoclassical transport coefficients and the generalized Spitzer function in 3D toroidal fusion devices (tokamaks and stellarators). This upgrade allows computations of the Spitzer function playing the role of current drive efficiency in the whole experimentally relevant temperature range, from mild temperatures where finite plasma collisionality effects are important to high temperatures where relativistic effects should be taken into account. Within the Galerkin method used for problem discretization over energy, relativistic effects are included into a set of matrices constant on a flux surface. Those matrices determine coefficients of a coupled set of integro-differential equations with a reduced dimension which is of the same form as in the non-relativistic case. For energy discretization of the linearized relativistic Coulomb collision operator, it is presented in spherical momentum space variables in the symmetric integral form derived directly from Beliaev-Budker expressions. The cancellation problem pertinent to the fully analytical representation of Braams and Karney [Phys. Fluids B 1, 1355 (1989)] does not appear in this form. Examples of evaluation of relativistic transport coefficients and the Spitzer function are presented.

Discriminants of noncommutative algebras and their applications

In this paper, we survey some recent developments on the discriminants of noncommutative algebras and some discriminant formulas. We also give applications of discriminants to automorphism problem, isomorphism problem, cancellation problem, Tits alternative principle and Azumaya locus.

Zariski cancellation problem for non-domain noncommutative algebras

We study Zariski cancellation problem for noncommutative algebras that are not necessarily domains.

Attribute Priority Arrangement of Cancellations in the Life Insurance Using Rough Set

This article presents a method for the rough set which attributes priority arrangement of cancellations in the life insurance. The number of canceled documents on the rise plus they're oscillatory and also the rates of cancellations in constant fluctuation, which requires searching in the problem of cancellations of this document, needs to be investigated in the future. It is obvious that these cancellations negatively affect the result operations of insurance companies. The article identifies the most important variables that affect the rates of cancellations and so as to reach solutions that lead to reducing the number of canceled documents by using the Rough model. The rough model was used to identify the determinants of cancellations in the life insurance of the Egyptian insurance market, so as to reach solutions that lead to reduce the number of canceled policies and find solutions to them. These findings prove that the most important factors that affect the cancellations for insurance policies are policy premiums, insurance period and age of policyholders, respectively.

Design and Evaluation of “BTTN”: A Backscattering Tag-to-Tag Network

Radio frequency (RF)-powered backscatter communication between passive tags holds tremendous potential as an enabling technology for a ubiquitous “Internet of Things.” We develop a backscattering tag-to-tag network (BTTN), comprised of passive tags capable of large-scale, passive, and multihop communication with each other via backscatter modulation of an external RF excitation signal. The low sensitivity and lack of active demodulator on passive tags present significant challenges to the communication, including a unique phase cancellation problem, which significantly affects the range and robustness of a passive tag-to-tag link. We overcome these challenges using innovative tag architecture and also develop a novel multiphase backscatter modulation technique with a learning mechanism that overcomes the phase cancellation problem. This improves the link performance bringing passive tag-to-tag communication closer to practical use. The additional hardware compared to the conventional radio frequency identification tag architecture includes one more terminating impedance in the modulator. The data rate is reduced due to backscatter at two different phases while the increase in the power consumption is negligible. We develop prototype BTTN tag hardware and firmware and evaluate its performance. The prototype achieves link ranges of up to 3 m at 5 kb/s with an excitation power level of only -20 dBm while successfully overcoming phase cancellation. We further extend BTTN operation to a multihop network where we demonstrate a four hop link capable of communicating over 12 m under similar conditions.

Blind speech intelligiblility enhancement by a new dual modified predator-prey particle swarm optimization algorithm

This paper addresses the problem of acoustic noise cancellation by adaptive filtering algorithms. To deal with acoustic noise reduction and speech enhancement problems, we propose to use the modified predator-prey particle swarm optimization (MPPPSO) to design a new dual adaptive noise canceller based on swarm intelligence heuristic search. The proposed dual MPPPSO algorithm improves the single-channel PPPSO algorithm convergence speed behavior when a large filter length is used. Also, the proposed algorithm leads to a low steady-state error in comparison with the single-channel PPPSO algorithm behavior which fails with large filters length and non-stationary input. The proposed dual MPPPSO algorithm shows significant improvement in the system mismatch (SM) and Output signal-to-noise ratio (SNR) values. We present the simulation results of the proposed dual MPPPSO algorithm that confirm its superiority and good performances in comparison with the single-channel PPPSO and the two-channel normalized least mean square (2C-FNLMS) algorithm.

A Study on Support Method of Consulting Service Using Text Mining

This study aims to build a support method for consulting service companies allowing them to respond to client demands regardless of the expertise of the consultants. With an emphasis on the revitalization of small and medium-sized enterprises, the importance of support systems for consulting services for small and medium-sized enterprises, which support solving problems that are difficult to deal with by an enterprise, is increasing. Consulting companies can respond to a wide range of management consultations; however, because the contents of a consultation are widely and highly specialized, a service proposal and the problem detection depend on the experience and intuition of the consultant, and thus a stable service may occasionally not be provided. Therefore, a support system for providing stable services independent of the ability of consultants is desired. In this research, as the first step in constructing a support system, an analysis of customer information describing the content of a consultation with the client companies is conducted to predict the occurrence of future problems. Text data such as the consultant’s visitation history, consultation content by e-mail, and call center content are used in the analysis because the contents explain not only the current problems but also possibly contain future problems. This paper describes a method for analyzing the text data by employing text mining. In the proposed method, by combining a correspondence analysis with a DEA (Data Envelopment Analysis) discriminant analysis, words that are strongly related to problem detection are extracted from a large number of words obtained from text data, and variables of the DEA discriminant analysis are reduced and analyzed. The proposed method focuses on a cancellation of contract problems. The cancellation problem does not include uncertainty; it is clearly known whether the contract of the consulting service is being updated or cancelled. In this study, computer experiments were conducted to verify the effectiveness of the proposed method through a comparison with an existing method. The results of the verification experiment are as follows. First, there is a possibility of discovering new factors that cannot be determined from the intuition and experience of the consultant regarding the target problem. Second, through a comparison with the existing method, the effectiveness of the proposed method was confirmed.

Estimating Parameters of Nonlinear Systems Using the Elitist Particle Filter Based on Evolutionary Strategies

In this paper, we present the elitist particle filter based on evolutionary strategies EPFES as an efficient approach to estimate the statistics of a latent state vector capturing the relevant information of a nonlinear system. Similar to classical particle filtering, the EPFES consists of a set of particles and respective weights which represent different realizations of the latent state vector and their likelihood of being the solution of the optimization problem. As main innovation, the EPFES includes an evolutionary elitist-particle selection scheme which combines long-term information with instantaneous sampling from an approximated continuous posterior distribution. In this paper, we propose two advancements of the previously published elitist-particle selection process. Further, the EPFES is shown to be a generalization of the widely-used Gaussian particle filter and thus evaluated with respect to the latter: First, we consider the univariate nonstationary growth model with time-variant latent state variable to evaluate the tracking capabilities of the EPFES for instantaneously calculated particle weights. This is followed by addressing the problem of single-channel nonlinear acoustic echo cancellation as a challenging benchmark task for identifying an unknown system of large search space: the nonlinear acoustic echo path is modeled by a cascade of a parameterized preprocessor to model the loudspeaker signal distortions and a linear FIR filter to model the sound wave propagation and the microphone. By using long-term information, we highlight the efficacy of the well-generalizing EPFES in estimating the preprocessor parameters for a simulated scenario and a real smartphone recording. Finally, we illustrate similarities between the EPFES and evolutionary algorithms to outline future improvements by fusing the achievements of both fields of research.

Lo ‘sbattezzo’, tra libertà religiosa e norme implicite. Spunti di diritto comparato

SOMMARIO: 1. Considerazioni introduttive - 2. Il quadro normativo - 3. Le soluzioni giurisprudenziali - 4. Riflessioni conclusive. The ‘debaptism’, between religious freedom and implicit rules. Hints of comparative law ABSTRACT: The problem of cancellation from baptismal registers seems to have come to a final solution, thus being no more interesting. Nonetheless, it can still be useful to analyse it from a comparative point of view. The study of the various solutions proposed by the different legal systems allows finding out ‘implicit’ juridical principles, which condition the interpretation and the implementation of positive rules. It can be especially remarked a convergence of arguments and results between legal systems formally inspired to distinct models of State-religions’ relationship - such as the French and the Italian legal systems. This convergence highlights the existence, at a latent level, of common cultural conceptions of the religious experience, fashioned by the Christian religious paradigm; these conceptions tend to shape the concrete contents of both the right to religious freedom, and the right to personal identity, protected by personal data laws.

Convex Combined Adaptive Filtering Algorithm for Acoustic Echo Cancellation in Hostile Environments

Research into combined adaptive filters has been attracting considerable attention; the performance of which is generally superior to that of the individual component filters. Formulating an adaptive filtering algorithm to handle a range of cases can be very difficult, particularly in complicated scenarios. This paper applies a robust convex combination method to the problem of acoustic echo cancellation. According to the minimum mean square error criterion, we first derive the optimal combination factor for a combination adaptive filter with two component filters. Next, we provide an approximation method to the inaccessible optimal combination factor. Finally, we extend this approximated factor to a robust one so that it is applicable even in situations with strong a ambient impulsive noise (IN) and abrupt changes in the echo channel. To do this, we non-linearly transfer the approximated combination factor so that this combination factor exhibits less transient time during the adaptation process of the combination factor and a fewer fluctuations in its steady state. Moreover, we detect the presence of the strong ambient IN and force the combined system output mainly contributed by one of the two component adaptive filters which is less sensitive to the the strong IN. We adopted computer simulations combining two affine projection sign algorithms with different step sizes as an example. Simulation results show that the proposed method is superior to comparable algorithms in terms of the normalized mean squared deviation and echo return loss enhancement.

Mitigation of Phase Cancellation for Efficient Decoding and RF Energy Harvesting in Tag-to-Tag Communications

In this paper, we investigate a phase cancellation problem that occurs in tag-to-tag communication systems. These are the systems wherein several tags communicate with each other by backscattering an external constant wave signal. A transmitting tag modulates baseband information into the reflected signal using backscatter modulation. At the receiving tag, the received signal is the superposition of the transmitted signals by the carrier emitter and the transmitting tag. The resulting signal is demodulated using the envelope detector that causes the phase cancellation problem. This problem exists in all tag-to-tag communication systems and largely impacts on the reliability and communication range. We theoretically analyze and experimentally demonstrate this problem for the tags that use amplitude-shift keying-based backscattering. We propose an algorithm for the mitigation of the phase cancellation based on the phase rotation control. We examine the performance of the proposed algorithm through theoretical analysis and computer simulations. We confirm that the proposed algorithm can significantly mitigate the phase cancellation.

A new robust adaptive algorithm based adaptive filtering for noise cancellation

Signal de-noising has been sparked and given a great attention by signal processing community since its applications are found in a diverse range of digital signal processing and computer vision problems. To improve signal quality, phase, frequency and power are the important features that should be preserved during the de-noising process. Adaptive filters have been widely used for this purpose due to their ability to cancel out noise signal from the corrupted one precisely. This paper presents a robust adaptive estimator for solving the problem of signal noise cancellation, based on a new adaptive algorithm derived from a new constrained optimization. Simulation results evaluated using MATLAB show that the proposed algorithm is appropriate for several forms of signals contaminated by diverse levels of noise power. The performance of the proposed algorithm is illustrated to be preferable in terms of the power signal to noise ratio, mean square error and time of speed convergence of filter parameters. It is compared to other conventional approaches such as least mean square and normalized least mean square algorithms with various values of white noise power, variance. It exhibits lower steady-state error and faster convergent time than the other implementations. Finally, an efficient performance is achieved comparable with recursive least square and affine projection algorithms.

Performance Analysis of 12Slot with Various Rotor Pole Numbers HE-FSM for HEV Application

This paper presents performance analysis of 12Slot with various rotor pole numbers Hybrid Excitation Flux Switching Machine (HEFSM) for Hybrid Electric Vehicles (HEVs) application. HEFSM has carried out by combining the advantage of Permanent Magnet (PM) machines and DC Field Excitation Coil (FEC) synchronous machines. Previously, most of HEFSM structure having FEC windings in theta direction that create a problem of flux cancellation that will affect the performances of the machine. Thus, a design of 12Slot HEFSM with FEC wounded in radial direction is proposed to eliminate the flux cancellation effect. At first, armature coil arrangement test at no-load condition is conducted to analyze PM flux. Furthermore, induced voltage and cogging torque at open circuit condition are investigated based on 2D finite element analysis (FEA). Finally, torque and power performances are also examined at maximum FEC and armature current densities. The outcomes demonstrate that 12S-14P configuration has the highest PM flux linkage, torque, power and less distortion of back-emf waveform which are required to be used as a motor in HEVs. The highest torque and power achieved are 220.15Nm and 92.45kW, respectively.

A conservative scheme of drift kinetic electrons for gyrokinetic simulation of kinetic-MHD processes in toroidal plasmas

A conservative scheme of drift kinetic electrons for gyrokinetic simulations of kinetic-magnetohydrodynamic processes in toroidal plasmas has been formulated and verified. Both vector potential and electron perturbed distribution function are decomposed into adiabatic part with analytic solution and non-adiabatic part solved numerically. The adiabatic parallel electric field is solved directly from the electron adiabatic response, resulting in a high degree of accuracy. The consistency between electrostatic potential and parallel vector potential is enforced by using the electron continuity equation. Since particles are only used to calculate the non-adiabatic response, which is used to calculate the non-adiabatic vector potential through Ohm's law, the conservative scheme minimizes the electron particle noise and mitigates the cancellation problem. Linear dispersion relations of the kinetic Alfvén wave and the collisionless tearing mode in cylindrical geometry have been verified in gyrokinetic toroidal code simulations, which show that the perpendicular grid size can be larger than the electron collisionless skin depth when the mode wavelength is longer than the electron skin depth.