Generation and Propagation of Partially Coherent Power-Exponent-Phase Vortex Beam

We report on a partially coherent power-exponent-phase vortex beam (PC-PEPV), whose spatial coherence is controllable and the initial phase exhibits a periodic power exponential change. The PC-PEPV beam was generated experimentally with various spatial coherence widths, and its propagation properties were studied both numerically and experimentally. By modulating the topological charge (TC) and power order of the PC-PEPV beam, the structure of the vortex beam can be adjusted from circular to elliptic, triangular, quadrangle, and pentagon. When the power order is odd, the PC-PEPV beam with a negative TC can be generated, and the profiles of the PC-PEPV beam can be precisely controlled via adjusting the value of the power order. For the case of high spatial coherence width, the number of the dark cores in the polygonal intensity array of the PC-PEPV beam equals the magnitude of the TC. However, when decreasing the spatial coherence width, the dark cores vanish and the intensity gradually transforms into a polygonal light spot. Fortunately, from the modulus and phase distributions of the cross-spectral density (CSD), both the magnitude and sign of the TC can be determined. In the experiment, the modulus and phase distribution of the CSD are verified by the phase perturbation method. This study has potential applications in beam shaping, micro-particle trapping, and optical tweezers.

The Effect of Functionally Graded Materials on Temperature during Frictional Heating: Under Uniform Sliding

The mathematical model of heating process for a friction system made of functionally graded materials (FGMs) was proposed. For this purpose, the boundary-value problem of heat conduction was formulated for two semi-spaces under uniform sliding taking into consideration heating due to friction. Assuming an exponential change in thermal conductivities of the materials, the exact, as well as asymptotic (for small values of time), solutions to this problem were obtained. A numerical analysis was performed for two elements made of ZrO2–Ti-6Al-4V and Al3O2–TiC composites. The influence of the gradient parameters of both materials on the evolution and spatial distributions of the temperature were investigated. The temperatures of the elements made of FGMs were compared with the temperatures found for the homogeneous ceramic materials.

Explosion and high-temperature plasma-as a consequence of the exponential equation of motion of gas molecules

In this paper, an exponential equation of motion for gas molecules is derived for the first time. The paper shows that the Kadic-Edelen forces, written in 1983 by analogy with electrodynamics, are forces that act on the momentum of particles as on a charge. The paper considers the application of the centrally symmetric force of the tensor compensating field in gas in the active state. It is shown that the intensity tensor in the gas is diagonal, so it leads to an increase in the momentum of the gas molecules exponentially in the direction of their movement. Thus, there is an exponential change in the kinetic energy of the gas molecules in the volume where the centrally symmetric intensity tensor acts. The action of a large positive intensity tensor in the gas leads to an explosion and high-temperature plasma.

The DNA of VUCA

“The DNA of VUCA: A Framework for Building Learning Agility in an Accelerating World” presents a practical guide to building learning agility and resilience for leaders to thrive in the face of crisis, disruption, complexity, and exponential change. It decomposes the term VUCA into two elements—volatility and complexity (which are best understood and addressed rationally) and uncertainty and ambiguity (which typically generate strong emotional reactions such as fear, stress, and anxiety and are best addressed by communication, emotional support, and human connection). Preparing leaders to thrive in VUCA times requires that they increase their exposure to diverse, novel, and adverse experiences (DNA) so they build capabilities and comfort in making decisions and taking decisive action under conditions of uncertainty and risk and projecting confidence and clarity in leading people through times of doubt and distress. In addition, leaders need to build their capacity to reflect on their experiences to see meaningful patterns and make informed choices about the best course of action going forward.

On the radio frequency dependence of the pulse delay phenomenon in PSR B0943+10

We report the result of measurements of a gradual shift of the integrated pulses towards later spin phase of the anomalous pulsar B0943+10 at the high radio frequencies. We have used observations from the Arecibo Observatory and the GMRT at 327 and 325 MHz correspondingly. For the measurements we have proposed a special method for calculating the correct positions of the partially merged two components of the pulse profile shape with significant temporal changes in their amplitude ratio. The exponential change in the pulse phase with an amplitude of 4 ms and characteristic time of about 1 hour has been found. Comparison of our measurements at 325 and 327 MHz with those at the lower frequencies of 25–80, 62 and 112 MHz have shown that the character of the process does not depend on frequency across a wide frequency range. The result is very important for constraining the nature of the delay. It supports the assumption that the process results from changes in the vacuum gap near the surface of the pulsar. The further correlation between changes in the pulse phase and its intensity is discussed.

EEG Channel Selection Using A Modified Grey Wolf Optimizer

Consider an increasingly growing field of research, Brain-Computer Interface (BCI) is to form a direct channel of communication between a computer and the brain. However, extracting features of random time-varying EEG signals and their classification is a major challenge that faces current BCI. This paper proposes a modified grey wolf optimizer (MGWO) that can select optimal EEG channels to be used in (BCIs), the way that identifies main features and the immaterial ones from that dataset and the complexity to be removed. This allows (MGWO) to opt for optimal EEG channels as well as helping machine learning classification in its tasks when doing training to the classifier with the dataset. (MGWO), which imitates the grey wolves leadership and hunting manner nature and which consider metaheuristics swarm intelligence algorithms, is an integration with two modification to achieve the balance between exploration and exploitation the first modification applies exponential change for the number of iterations to increase search space accordingly exploitation, the second modification is the crossover operation that is used to increase the diversity of the population and enhance exploitation capability. Experimental results use four different EEG datasets BCI Competition IV- dataset 2a, BCI Competition IV- data set III, BCI Competition II data set III, and EEG Eye State from UCI Machine Learning Repository to evaluate the quality and effectiveness of the (MGWO). A cross-validation method is used to measure the stability of the (MGWO).

Electrical Resistivity, Thermoelectric Power and I-V Characteristics of Sb-Se Thin Films at Different Compositions.

Sb-Se thin films of varying composition have been deposited on glass substrates at room temperature. These films were annealed at temperature interval of 50 0K. The electrical resistivity (ρ) and thermoelectric power (α) of same films were measured. The resistance of semiconducting films decreases rapidly on heating showing negative temperature coefficient of resistance (T.C.R.). The composition dependent resistivity shows exponential change, sharp fall of resistivity may be attributed due to increase of metallic ‘Sb’ in Sb-Se thin films. The composition dependent activation energy of Sb-Se thin films has been calculated. The activation energy (∆E) of semiconducting films was found to increase with selenium concentration. For different compositions thermoelectric power (α) increases upto 70 at. wt.% of Se concentration and then slowly decreases. The I-V characteristics of Sb-Se thin films were measured using copper (Cu) contacts. The films show ohmic conduction for different applied voltages as well as various concentrations of Selenium (Se) in Sb-Se thin films