Maximum Number Of Sources Research Articles

Efficient FFT based multi source DOA estimation for ULA

An accurate and fast direction-of-arrival (DOA) estimation method for multiple targets in additive white Gaussian noise is presented in this paper, where the maximum number of sources’ DOA can be estimated is N/2 for N sensors. In the proposed method, the expression of each DFT bin is derived in polynomial form by using the consecutive multiplication. Then the linearity of DFT bins is used to calculate the DOA. Moreover, the complex-valued least squares framework is adopted to extend the proposed method for multiple snapshots. The effect of noise on DOA estimation is simulated. And simulation results validate the advantages of the proposed method.

Using the directed search method to select the degree of centralization of heat supply schemes in order to ensure the environmental sustainability of a settlement

An algorithm is proposed for the formalized choice of the degree of centralization of the heat supply scheme in order to ensure the environmental sustainability of the settlement. The algorithm is based on a directed search for combinations of centralization and decentralization of the scheme, with the construction of networks of optimal topology for each of the compared options. The calculation begins with a variant of a decentralized heat supply scheme (maximum number of sources), followed by a reduction in heat supply sources by one at each iteration, up to full centralization to achieve ecological balance in the settlement. Taking into account the directed search proposed in the algorithm and excluding non-optimal combinations at each iteration, the number of calculations is significantly reduced compared to a simple enumeration of options. In addition to practical application, the algorithm allows you to study the “heat load density” indicator, which affects the decision on the degree of centralization of the heat supply scheme, and at the same time take into account the uneven distribution of consumers on the ground, their number, the heterogeneity of heat loads and achieving a balance in the environment.

Comparative Analysis of International Databases of Adverse Drug Reactions

In 1968 the World Health Organisation initiated the development of an international programme for collection of data from the maximum number of sources about potential adverse effects of medicines. In order to implement this programme, a number of databases were created, such as the global database VigiBase, the European database EudraVigilance, and the database of the Eurasian Economic Union (EAEU). The aim of the present study was to compare approaches of the international spontaneous reports databases to collection, processing, and analysis of information on adverse drug reactions. It was demonstrated that the international databases VigiBase, EudraVigilance, and the EAEU database of adverse drug reactions contain different numbers of spontaneous reports, but serve the same objectives, namely to collect, process, and analyse information submitted as spontaneous reports. Unlike VigiBase that contains reports on authorised medicines coming from the national pharmacovigilance centres only, EudraVigilance also receives data from marketing authorisation holders and has reports on adverse drug reactions observed during clinical trials. The exchange of information between countries ensures rapid identification of safety signals concerning potential risks of medicines, and increases the likelihood of detecting rare and late-onset adverse reactions that may go unnoticed when analysing national data in a particular country. Spontaneous reports databases are an essential tool of the international drug safety monitoring community. Effective measures in this area will ultimately help to improve patients’ health and quality of life.

2-D direction finding using parallel nested arrays with full co-array aperture extension

Sparse arrays, such as nested arrays, are able to resolve more sources than sensors because their difference co-arrays can provide O(L2) degrees-of-freedom (DOFs) with L physical sensors. Most of the existing nested array direction-finding algorithms apply the spatial smoothing technique to realize this DOFs enhancement. One shortcoming of this type of methods is the efficient co-array aperture is reduced in processing the spatial smoothing, resulting in the DOFs are not fully utilized. In this paper, we propose a new approach using two parallel linear nested arrays to contribute full DOFs for two-dimensional direction-finding. To exploit the entire DOFs, we perform the vectorization of multiple fourth-order cumulant matrices and take the average of their co-array covariance matrices, instead of the spatial smoothing of the vectorization of the data covariance matrix. Based on a well-posed identification analysis, we show that the proposed approach can identify the number of sources approximately three times than the algorithms using the spatial smoothing technique. For example, for a two-level parallel nested array of 2+2 sensors in each subarray, the maximum number of sources that can be resolved by the proposed approach is 32, whereas, for most of the existing algorithms, the number reduces to 10.

Literature Monitoring for Pharmacovigilance

Literature monitoring is a complicated aspect of pharmacovigilance. The guidelines on good practice of pharmacovigilance of the Eurasian Economic Union recommend the using of a biomedical reference database containing the maximum number of sources for the monitored drugs, which necessitates the selection of such a database. The aim of the paper is to compare the coverage and functionality of international databases of medical publications recommended for monitoring literature within pharmacovigilance in terms of coverage and functionality. The paper analyzes the coverage and presents the comparison of the results of the search in the databases Embase®, MEDLINE® and eLibrary for 35 drugs. It have been shown that the search in the Embase® database provides the maximum number of sources. In addition, the paper shows the applicability special PV Wizard functionality which facilitate the building of search strategies with high recall, sensitivity and compliance.

Mixed near-field and far-field source localization utilizing symmetric nested array

Existing mixed near-field and far-field source localization algorithms rely on uniform linear array (ULA), and the maximum number of sources that they can detect is less than the sensor number. As a comparison, recently proposed nested array can provide higher number of consecutive lags with the same sensor number, enabling us to extend it to mixed source localization scenario. Instead of utilizing generalized nested array, we design a symmetric nested array (SNA) for mixed source localization. By constructing a fourth-order cumulant matrix that only related to DOA information, the newly designed symmetric nested array exhibits at least of 4N+4MN−2M−3 consecutive lags with only 2M+2N−1 sensors. A compressive sensing (CS) based approach is exploited to achieve DOA estimation of all sources by fully using these consecutive lags. Based on the estimated DOAs, the range of near-field sources is obtained by 1-D spectral search, and the near-field and far-field sources are classified successively in range domain. By conducting numerical simulations, we show the superiority of the proposed algorithm in terms of estimation accuracy, number of required array sensors, and resolution ability compared with previous algorithms.

Super-Resolution of Positive Sources: The Discrete Setup

In single-molecule microscopy it is necessary to locate with high precision point sources from noisy observations of the spectrum of the signal at frequencies capped by ${f_c}$, which is just about the frequency of natural light. This paper rigorously establishes that this super-resolution problem can be solved via linear programming in a stable manner. We prove that the quality of the reconstruction crucially depends on the Rayleigh regularity of the support of the signal; that is, on the maximum number of sources that can occur within a square of side length about $1/{f_c}$. The theoretical performance guarantee is complemented with a converse result showing that our simple convex program is nearly optimal. Finally, numerical experiments illustrate our methods.

On the improvement of the quality of service of video services in an asynchronous transfer mode network using forced frame refreshment

A method of improving the quality of service of video services in an asynchronous transfer mode network under congestion periods is considered. In the event of cell loss carrying intraframe coded data, the decoder asks the encoder to refresh the codec by intraframe coding the next frame. To prevent the network from overloading, constraints are imposed on the maximum number of sources that refresh the whole picture simultaneously at the same video frame interval and the distance between two consecutive refreshments in each video connection. The rate of this refreshment depends on the network load and the number of sources sharing the network. It is shown that there is a minimum distance within two consecutive refreshments for each video connection where both network performance and perceived image quality are optimized.

On unique localization of constrained-signals sources

Conditions for unique localization of radiating sources by passive sensor arrays are presented. Unlike in previous analyses, the case wherein the signals are constrained to certain loci in the complex plane is addressed. Two types of constraints are considered. The first includes the case of constant-amplitude signals and the second includes the case of complex-exponential signals. The conditions specify the maximum number of sources that can be uniquely localized by a general array satisfying some mild geometrical constraints in terms of the number of sensors and the rank of the correlation matrix of the sources. This number exceeds substantially the corresponding number for the unconstrained-signals case.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

On unique localization of multiple sources by passive sensor arrays

Necessary and sufficient conditions are derived for the unique localization of narrowband sources having the same known center frequency by passive sensor arrays. The conditions specify the maximum number of sources that can be uniquely localized by a general array that satisfies some mild geometric constraints. The conditions are expressed in terms of the number of sensors and the rank of the correlation matrix of the sources. Two different conditions are presented. The first guarantees uniqueness for every batch of sampled data. The second, which is weaker, guarantees uniqueness for almost every batch of sampled data, with the exception of a set of batches of measure zero. It is shown that a condition that is slightly weaker than the second one is also necessary. >