Improvement of transient and small signal stability in micro grid by hybrid technique with virtual synchronous generator control scheme

In this article, a hybrid technique is proposed for improving the transient and small signal response in micro grid using virtual inertia. The proposed hybrid technique is the combined execution of both the emperor penguin optimizer (EPO) and butterfly optimization algorithm (BOA), and hence it is called EPOBOA technique. The major objective of the EPOBOA technique is to “optimize the control parameters to regulate the changes occurred in the grid parameter such as voltage and frequency based on the variations of inertia”. Here, the EPO is executed to modify the parameters of virtual synchronous generator units to achieve the objective function. The searching behaviour of the EPO is adapted by using the hunting behaviour of BOA. The proposed technique is executed in MATLAB/Simulink work site, and the experimental results are analyzed under three test cases: normal condition, irradiation change condition, and load change condition. The performance of the proposed technique is compared with different existing techniques and the calculated frequency deviation index of the proposed technique in all the cases is 0.0051, 0.0045, and 0.0047 and found to be very optimal compared with existing methods. Overall, the experimental outcomes show that the proposed EPOBOA method is more efficient and confirm its ability to solve the issues.

Race is Still Black and White: Voluntary Racial Phenotypic Change Elicits Meaning Threat and Backlash

We offer evidence that a target who voluntarily changes his/her racial phenotypic features causes perceivers to engage in two-pronged social policing of racial group boundaries: (a) vilifying and disliking the target (cognitive and affective backlash; external policing) (Experiments 1a-1b, 2, & 3) and (b) increasing own racial essentialism, in response to a meaning threat (internal policing) (Experiment 3). In all experiments, participants received a vignette of a protagonist that underwent non-elective surgery (white/Asian, Experiments 1a-1b; white/Black, Experiments 2-3). In the voluntary change condition, the protagonist asks that the surgeon change his/her racial features to resemble that of a different race whereas, in the involuntary change condition the protagonist asks that the surgeon keep his/her racial features intact (Experiment 1: eye shape, Experiment 2: Afrocentric features). Findings supported the predictions and showed a dissociation between similarity and categorization judgments, underscoring the essentialized versus socially constructed nature of beliefs about race.

Indexing of Heatwaves in Ukraine

During the last decades, the number of heatwaves (HWs) has increased worldwide, as well as in Ukraine. It is very important to determine the duration, intensity, and other HW parameters, in particular under climate change condition. For this purpose, various heatwave indices and characteristics are used. The aims of this study were (1) to investigate heatwave indices and their characteristics over the territory of Ukraine for the reference period 1981–2010, as well as to examine the extreme heatwave event of 2010 and (2) to make a comparison and establish a statistical relationship between the HW indices and their characteristics and to assess their suitability and sensitivity to changes in the modern climate of Ukraine. On the basis of 49 selected stations, daily values of maximum air temperature (Tmax) in the summer months June to August of 1981–2010 were used to determine two heatwave indices (HWMI (heatwave magnitude index) and HWMId (heatwave magnitude index daily)) and five heatwave characteristics (HWM (heatwave mean), HWA (heatwave amplitude), HWN (heatwave number), HWD (heatwave duration), HWF (heatwave day frequency)). The calculated indices of heatwaves appeared to be sufficiently sensitive to minor changes in the daily maximum air temperature. HWMId was found to be more sensitive to temperature changes than HWMI. The heatwave characteristics of the HWN, HWF, HWM, and the HWMId climate index proved to be the most informative in the study of heatwaves in Ukraine.