Design of Finite-Length Irregular Protograph Codes with Low Error Floors over the Binary-Input AWGN Channel Using Cyclic Liftings

We propose a technique to design finite-length irregular low-density parity-check (LDPC) codes over the binary-input additive white Gaussian noise (AWGN) channel with good performance in both the waterfall and the error floor region. The design process starts from a protograph which embodies a desirable degree distribution. This protograph is then lifted cyclically to a certain block length of interest. The lift is designed carefully to satisfy a certain approximate cycle extrinsic message degree (ACE) spectrum. The target ACE spectrum is one with extremal properties, implying a good error floor performance for the designed code. The proposed construction results in quasi-cyclic codes which are attractive in practice due to simple encoder and decoder implementation. Simulation results are provided to demonstrate the effectiveness of the proposed construction in comparison with similar existing constructions.Comment: Submitted to IEEE Trans. Communication

Lowering the Error Floor of LDPC Codes Using Cyclic Liftings

Cyclic liftings are proposed to lower the error floor of low-density parity-check (LDPC) codes. The liftings are designed to eliminate dominant trapping sets of the base code by removing the short cycles which form the trapping sets. We derive a necessary and sufficient condition for the cyclic permutations assigned to the edges of a cycle $c$ of length $\ell(c)$ in the base graph such that the inverse image of $c$ in the lifted graph consists of only cycles of length strictly larger than $\ell(c)$. The proposed method is universal in the sense that it can be applied to any LDPC code over any channel and for any iterative decoding algorithm. It also preserves important properties of the base code such as degree distributions, encoder and decoder structure, and in some cases, the code rate. The proposed method is applied to both structured and random codes over the binary symmetric channel (BSC). The error floor improves consistently by increasing the lifting degree, and the results show significant improvements in the error floor compared to the base code, a random code of the same degree distribution and block length, and a random lifting of the same degree. Similar improvements are also observed when the codes designed for the BSC are applied to the additive white Gaussian noise (AWGN) channel

Modeling Contention Behavior of Machine-Type Devices over Multiple Wireless Channels

Machine-Type Communication (MTC) is expected to account for the largest proportion of the regular connected devices with a dramatic growth from 2 billion at the end of 2011 to 12 billion by the end of 2020. Leading the largest submarket within the Internet of Things (IoT) submarket, it has been one the most attractive research areas as it has received remarkable attention recently from both academic and industry. Deployments of unattended devices characterized by their small-size and infrequent data pattern over Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) have been focused in this Thesis. MTC devices may utilize contention-based random access to transmit over the LTE network to have their data delivered. However, there has been limited attention to analytical characterization of contention-based behavior when unsaturated MTC traffic is considered. Furthermore, the existing efforts lack the analytical model capturing MTC contention behavior and utilizing it for MTC over LTE transmission use cases and scenarios. Thus, in this Thesis we focus on proposing a novel mathematical model which characterizes contention behavior in a multi-channel environment being applicable to various MTC over LTE scenarios. Further, the proposed mathematical model has been confirmed by extensive protocol-level simulations. Regarding the performance evaluation, in this Thesis we have assessed two distinct variations of ALOHA-type algorithms to characterize the MTC contention behavior. Proposing a novel mathematical model which captures contention behavior based on the system attributes and entities, we have employed the ALOHA-type channel access methods and mathematical processes (e.g. Markov chain) to investigate analytically three performance metrics including average access delay, average throughput and average number of users in the system.Furthermore, the proposed analytical characterization in the multi-channel environment is shown to be useful in quantifying the performance of contention-based Physical Random Access Channel (PRACH) procedure in 3GPP LTE. As a conclusion, the perfect convergence between analysis and simulation-level results confirms the rigorousness of the proposed model to be used for optimizing Random Access (RA) procedure or to be employed as a baseline in other relevant MTC over LTE research works

Heterogeneous Graph Learning for Acoustic Event Classification

Heterogeneous graphs provide a compact, efficient, and scalable way to model data involving multiple disparate modalities. This makes modeling audiovisual data using heterogeneous graphs an attractive option. However, graph structure does not appear naturally in audiovisual data. Graphs for audiovisual data are constructed manually which is both difficult and sub-optimal. In this work, we address this problem by (i) proposing a parametric graph construction strategy for the intra-modal edges, and (ii) learning the crossmodal edges. To this end, we develop a new model, heterogeneous graph crossmodal network (HGCN) that learns the crossmodal edges. Our proposed model can adapt to various spatial and temporal scales owing to its parametric construction, while the learnable crossmodal edges effectively connect the relevant nodes across modalities. Experiments on a large benchmark dataset (AudioSet) show that our model is state-of-the-art (0.53 mean average precision), outperforming transformer-based models and other graph-based models.Comment: arXiv admin note: text overlap with arXiv:2207.0793

Étude expérimentale de la dissipation d'énergie dans le régime d'écoulement de nappe dans un déversoir à étage muni de marches inclinées et d'un seuil

International audienceStepped spillway increases the hydraulic resistance against flow by using of step-made spillway floor and when the flow of water passing on steps, a significant part of energy dissipates and also reduces the risk of cavitation. In this experimental research, in order to increase the energy dissipation of stepped spillway, Steps has a reverse gradient and in other part of this tests in addition to create a reverse gradient in the steps at the same time the sill is also installed on the edge of the steps. Height, thickness of the sills is considered variable. The results show that in both Nappe Flow Regime and Skimming Flow Regime Change of gradient, sills height, thickness are effective to increase the energy loss but the effect of these parameters on the Nappe Flow Regime is much greater than Skimming Flow Regime. By analyzing the results of the experiments and compared with results from other studies, the research showed that the method used in this study has a better energy loss than other methods used in prior researches.Le déversoir à étages augmente la résistance hydraulique contre l'écoulement en utilisant un plancher en déversoir fabriqué à l'aide de marches et lorsque l'écoulement de l'eau circule sur les marches, une partie importante de l'énergie se dissipe et réduit également le risque de cavitation. Dans cette recherche expérimentale, afin d’augmenter la dissipation d’énergie de l’évacuateur à gradins, Steps dispose d’un gradient inversé et, dans une autre partie de celle-ci, vise également à créer un gradient inversé dans les gradins. En même temps, le seuil est également installé en bordure des marches. La hauteur et l'épaisseur des appuis sont considérées comme variables. Les résultats montrent que, tant dans le régime d'écoulement de nappe que dans le changement de régime d'écrémage, la pente, la hauteur et l'épaisseur des seuils sont efficaces pour augmenter la perte d'énergie, mais l'effet de ces paramètres sur le régime d'écoulement de nappe est beaucoup plus important que le régime d'écoulement d'écrémage. En analysant les résultats des expériences et en les comparant aux résultats d’autres études, les recherches ont montré que la méthode utilisée dans cette étude présentait une perte d’énergie plus importante que d’autres méthodes utilisées dans des recherches antérieures

PARAMETERS ESTIMATION OF FRACTIONAL ORDER SYSTEM WITH DOMINANT POLE USING CO-EVOLUTIONARY PARTICLE SWARM OPTIMIZZATION (CPSO) ALGORITHM

ABSTRACT This paper deals with fractional order systems parameters estimation by use of Co-evolutionary Particle Swarm Optimization (CPSO) method. in some cases such as fractional order systems identification in spite of existing different methods, it is difficult to obtain estimation of model structure parameters and generally it leads to solving the with constrained complex non-linear optimization problems and this topic is one of the identification challenges of these systems. Since some of systems are inherently fractional order and because of having special behavior in these systems which in its similar integer order systems are not found. There for necessity of fractional modeling is double for such systems. In this paper, at first, we assume that the measured out-input data exists and for approximation to reality is considered that these data has been corrupted with noise. Then considering model structure as the linear combination of fractional orthogonal basis functions by use of CPSO suitable algorithm leads to estimation of fractional order system parameters and related to the complexity level of master system, suitable or acceptable approximation is obtained. In finally, by simulating of physical-typical sample system in noisy conditions leads to system identification which gained results shows the effectiveness of presented method. KEYWORDS: Fractional Order Systems, Parameter Estimation, System Identification, Co-Evolutionary Particle Swarm Optimization (Cpso) Algorithms Although the mathematics of fractional calculations has a few hundred years old, but in the two decades ago, it has been attracted in research and applicable fields of various sciences. Also, it was seen that some of the real systems have inherent fractional order behaviour and for example we can refer to real systems such as: viscoelastic materials, cell diffusion processes, transmission of signals via strong magnetic fields and some systems with disturbance characteristics that they have inherent fractional order behaviour One of the features of behaviour of fractional order systems is presence of non-periodic modes that they are decay in polynomial form and also a behaviour that it is called long memory that we can't find its similarity in integer order rational systems . So, if modelling, identification, controlling and other studies on these systems want to be accurate and close to reality, it should be based on fractional order model of these systems. Even in integer order systems, modelling in the form of fractional order mode or controller design with fractional model is also more effective, because of its more degrees of freedom and also the systems with integer order are special state of fractional order systems. This topic has been shown in several researches, therefore, the importance of fractional models and their synthesis is clear in practic

Experimental survey of energy dissipation in nappe flow regime in stepped spillway equipped with inclined steps and sill

Stepped spillway increases the hydraulic resistance against flow by using of step-made spillway floor and when the flow of water passing on steps, a significant part of energy dissipates and also reduces the risk of cavitation. In this experimental research, in order to increase the energy dissipation of stepped spillway, Steps has a reverse gradient and in other part of this tests in addition to create a reverse gradient in the steps at the same time the sill is also installed on the edge of the steps. Height, thickness of the sills is considered variable. The results show that in both Nappe Flow Regime and Skimming Flow Regime Change of gradient, sills height, thickness are effective to increase the energy loss but the effect of these parameters on the Nappe Flow Regime is much greater than Skimming Flow Regime. By analyzing the results of the experiments and compared with results from other studies, the research showed that the method used in this study has a better energy loss than other methods used in prior researches

Investigating the Efficacy of Sumac Topical Solution Against Permethrin-resistant Human Head Lice

Background: The present study aimed at determining the efficacy of applying Rhus coriaria (Sumac) solution for the treatment of Permethrin-resistant head louse in patients, who used permethrin for at least 2 consecutive periods, but have not been cured.Methods: This study is a before-after clinical trial performed on 100 patients with pediculosis aged between 2 and 50 years old and both sexes. All patients had used Permethrin at least twice consecutively (with at least 14 days interval) according to correct instructions (on the first and 7th day), but they have not been cured. Each patient received 60ml of Rhus coriaria solution for 3 consecutive days, and the treatment was repeated again for another 3 days; then, the patients were followed-up on the 4th, 10th, and14th days after the treatment.Results: The results showed a significant difference in the severity of head lice infection and itching before the treatment and 14 days after the treatment (P<0.001).Conclusion: Rhus coriaria solution was more effective in eliminating head-louse infestations on 4, 10, and 14 days after the treatment and itching disappeared in most of the patients, while negligible complications were observed

Move to the Fourth-Generation Universities: A Systematic Scoping Review of Educational and Management Strategies

Background: Higher education is not uniform. There are significant differences between higher education systems among different countries and even among institutions in a similar education or system; therefore, identifying the various types of entrepreneurial activities helps the mission of fourth-generation universities. Objectives: The purpose of this study was to introduce the most important educational strategies to move towards fourth-generation universities. Methods: We systematically searched the international databases, including PubMed, Web of Science, Scopus, ISC, SID, and Google Scholar, until 2021 using some relevant keywords. Then, screening and selecting eligible articles according to inclusion criteria were done by two researchers independently. Results: Soft skills training, sustainable development training, training business law, reviewing the continuous training of professors, promoting ideation and creativity to solve problems, development of interdisciplinary training, decentralization of government accelerators and deployment of private accelerators, privatization of higher education, and internationalization are the most important educational strategies to move towards fourth-generation universities. One of the critical aspects and perspectives of the fourth-generation university is the development of job skills, professions, and competencies and empowerment of students and professors in line with the process of national development and solving society's problems scientifically. Conclusion: This research's analytical results help the universities design and implement their strategies to reach the fourth-generation universities according to the standard implementation models of the fourth-generation universities. Keywords: Universities, Education, Policy, Fourth-Generatio

Comparison of Forgiveness and Religious Commitment in Couples on the on the Brink of Divorce and Normal Couples

The rising rate of divorce in Iranian society is disconcerting. This study aimed at comparing religious commitment and forgiveness in couples on the rink of divorce and normal couples. The research method is descriptive and causal-comparative. To select the group of couples on the brink of divorce, firstly, the researcher referred to counseling units of the courts and law offices of various cities of the Guilan province. The cases of the couples who were qualified to enter the study were reviewed and of these cases 173 were selected based on availability. Then, 143 normal couples referring to the courts and offices of lawyers which the cause of their resort is nothing but the completions of the divorce case were selected through purposive sampling. They responded to Glock and Stark's Religious Commitment questionnaire, and Ray and et al Forgiveness scale. Obtained data were analyzed by Pearson Chi-squares, independent t-test, multivariate analysis of variance. The results showed that the mean of forgiveness and religious Commitment in couples on the brink of divorce and normal couples significantly different, that is, couples on the brink of divorce have less level of forgiveness than normal couples and in terms of faithfulness and ritual religious commitment, they scored less scores than normal couples. The remarkable difference between the two groups has important marital therapy implications for implementation of forgiveness-oriented intervention and also promotion of religious beliefs and ritual among couples in order to maintain and strengthen the marriage contract