We study the problem of recovering the phase from magnitude measurements; specifically, we wish to reconstruct a complex-valued signal x ∈ ℂn about which we have phaseless samples of the form yr = |〈ar, x〉|2, r = 1, ..., m (knowledge of the phase of these samples would yield a linear system). This paper develops a nonconvex formulation of the phase retrieval problem as well as a concrete solution algorithm. In a nutshell, this algorithm starts with a careful initialization obtained by means of a spectral method, and then refines this initial estimate by iteratively applying novel update rules, which have low computational complexity, much like in a gradient descent scheme. The main contribution is that this algorithm is shown to rigorously allow the exact retrieval of phase information from a nearly minimal number of random measurements. Indeed, the sequence of successive iterates provably converges to the solution at a geometric rate so that the proposed scheme is efficient both in terms of computational and data resources. In theory, a variation on this scheme leads to a near-linear time algorithm for a physically realizable model based on coded diffraction patterns. We illustrate the effectiveness of our methods with various experiments on image data. Underlying our analysis are insights for the analysis of nonconvex optimization schemes that may have implications for computational problems beyond phase retrieval.
The method of sensing coal spontaneous combustion temperature based on acoustic wave technology has the advantages of wide application scenarios and real-time continuity, but the precursor characteristics of acoustic wave signals in the process of coal spontaneous combustion have not yet been revealed. The study of acoustic effects and precursor characteristics in the process of coal spontaneous combustion provides a theoretical basis for the detection and warning of coal spontaneous combustion by acoustic wave method. The article firstly theoretically analyses the thermal damage rupture evolution process and acoustic wave transmission characteristics of coal rock. Three sizes of coal spontaneous combustion acoustic wave information testing systems were established to test the infrasound, acoustic emission and acoustic sound velocity information during coal heating and combustion. Using linear fitting, multiple fractal theory, Fourier transform and other methods, the paper analyse the temporal characteristics, temperature correlation, spatial characteristics, nonlinear characteristics and spectra of acoustic signals to reveal the precursor characteristics of acoustic signals in the process of spontaneous combustion of coal. The results show that with the increase of coal temperature, the infrasound sound pressure value increases paroxysmally, and the ringing counts, energy value and acoustic sound velocity of acoustic emission signals are positively correlated with the temperature. The infrasound signals and acoustic time changes were more obvious in the pre-coal spontaneous combustion period. The acoustic emission signal increases and changes more significantly after 100 ℃. The acoustic signal has spatial characteristics. With the increase of the distance from the heat source, the ringing count and energy change by decreasing. The speed of sound at different distances increases with increasing temperature, and the R2 of the speed-temperature fitting equation exceeds 0.9. The infrasound and acoustic emission signals have multiple fractal characteristics during coal heating and correspond well with the thermal rupture of spontaneous coal combustion. In addition, the main frequency of infrasound waves migrated and the amplitude of the main frequency increased during the process of coal warming. Finally, the acoustic emission test was carried out in the high-temperature anomaly area of the coal field. The acoustic emission signals in the temperature anomalies change significantly.
Organizational symmetry is a critical factor in enhancing organizational pride, which positively impacts job performance and organizational loyalty. In the academic environment, faculty members' affiliations are fundamental to universities' success, making the study of the relationship between these two concepts highly significant. The problem lies in the lack of studies examining the impact of organizational symmetry on organizational pride in Iraqi universities, particularly at Zakho University. There is also a need to understand how faculty members perceive this symmetry and how it can be enhanced to increase their pride in belonging to the university. The study aimed to analyze the effect of organizational symmetry, with its dimensions (loyalty, similarity, belonging), on enhancing organizational pride, with its dimensions (emotional and attitudinal), among faculty members. Zakho University was chosen as the field of study, and a sample of faculty members was selected, totaling 243. The fieldwork primarily relied on a descriptive-analytical approach, and a questionnaire waxas distributed to collect data from the study sample. This was done to describe and determine the availability of the study variables at the researched university and to examine their relationships using specific statistical measures and indicators (mean, correlation coefficient, regression) in SPSS. Based on the study's testing and analysis, several results were reached: the most significant was the strong positive relationship between organizational similarity and organizational pride, and shared values between teachers and the university were the most influential factor in enhancing organizational pride.
Management information systems, Economic history and conditions
It is demonstrated that identifying information-theoretic limitations of quantum Bell nonlocality alone cannot completely distinguish quantum theory from generalized nonsignaling theories. To this end, an information-theoretic concept of certifying nonobjective information by the Popescu-Rohrlich box fraction is employed. Furthermore, in the aforementioned demonstration, a partial answer to the question of what distinguishes quantum theory from generalized nonsignaling theories emerges beyond the one provided by the principle of information causality alone. This is accomplished by demonstrating that postquantum models identified by the information causality are isolated by the emergence of the Popescu-Rohrlich box fraction of nonobjective information in Bell-local boxes of a nonsignaling model, over the other nonsignaling models.