Analysis of daily solar irradiation variability and predictability in space and time is important for energy resources planning, development, and management. The natural variability of solar irradiation is being complicated by atmospheric conditions (in particular cloudiness) and orography, which introduce additional complexity into the phenomenological records. To address this question for daily solar irradiation data recorded during the years 2013, 2014 and 2015 at 11 stations measuring solar irradiance on La Reunion French tropical Indian Ocean Island, we use a set of novel quantitative tools: Kolmogorov complexity (KC) with its derivative associated measures and Hamming distance (HAM) and their combination to assess complexity and corresponding predictability. We find that all half-day (from sunrise to sunset) solar irradiation series exhibit high complexity. However, all of them can be classified into three groups strongly influenced by trade winds that circulate in a “flow around” regime: the windward side (trade winds slow down), the leeward side (diurnal thermally-induced circulations dominate) and the coast parallel to trade winds (winds are accelerated due to Venturi effect). We introduce Kolmogorov time (KT) that quantifies the time span beyond which randomness significantly influences predictability.

Introduction The coronavirus disease 2019 (COVID-19) pandemic has been unprecedented in recent history. The rapid global spread has demonstrated how the emergence of a novel pathogen necessitates new information to advise both healthcare systems and policy-makers. The directives for the management of COVID-19 have been limited to infection control measures and treatment of patients, which has left physicians and researchers alone to navigate the massive amount of research being published while searching for evidence-based strategies to care for patients. To tackle this barrier, we launched CovidReview.ca , an open-access, continually updated, online platform that screens available COVID-19 research to determine higher quality publications. This paper uses data from this review process to explore the activity and trends of COVID-19 research worldwide over time, while specifically looking at the types of studies being published. Materials and Methods The literature search was conducted on PubMed. Search terms included “COVID-19”, “severe acute respiratory syndrome coronavirus 2”, “coronavirus 19”, “SARS-COV-2”, and “2019-nCoV”. All articles captured by this strategy were reviewed by a minimum of two reviewers and categorized by type of research, relevant medical specialties, and type of publication. Criteria were developed to allow for inclusion or exclusion to the website. Due to the volume of research, only a level 1 (title and abstract) screen was performed. Results The time period for the analysis was January 17, 2020, to May 10, 2020. The total number of papers captured by the search criteria was 10,685, of which 2,742 were included on the website and 7,943 were excluded. The greatest increase in the types of studies over the 16 weeks was narrative review/expert opinion papers followed by case series/reports. Meta-analyses, systematic reviews, and randomized controlled trials remained the least published types of studies. Conclusions The surge of research that accompanied the COVID-19 pandemic is unparalleled in recent years. From our analysis, it is clear that case reports and narrative reviews were the most widely published, particularly in the earlier days of this pandemic. Continued research that falls higher on the evidence pyramid and is more applicable to clinical settings is warranted.

The accurate values of the initial velocity of bullets are significant for the quality and precision of small arms. The application of the simple measurement methods, during the tests of the weapon and ammunition, enables the determination of the velocity values from the group of shoots. The accuracy of bullet trajectory, appropriate trajectory correction parameters and terminal ballistics parameters are depended of the quality of initial conditions as initial velocity. The ballistic pendulum, as simple and old-design device, enhanced with optoelectronic encoder sensor and computer acquisition system, can be one of the good start-up device platform for measurement of velocity and observation of the terminal ballistics effects. The function principle of the considered device is based on the energy conservation. Initial data are mass of bullet, mass and dimension of pendulum, and result is velocity, according to the values of time and angle of pendulum. The output signals of measured angle in time are captured, and as required values for calculation the velocity on the microprocessor platform, for each shoot in the test group. The microprocessor platform saves measured and calculated values in memory and generates statistic report of results. The presented method can improve weapon and ammunition tests, by decreasing the time of measurement acquisition and increasing the quality and speed of results without errors. The method and system is simple and low-cost, and enables the design of small arms ammunition database of testing results.

We present results of numerical simulations of a stratified reservoir with a three-layer stratification, subject to an oscillating surface shear stress. We investigate the effect of sloped endwalls on mixing and internal wave adjustment to forcing within the basin, for three different periods of forcing. The simulations are carried out at a laboratory scale, using large-eddy simulation. We solve the three-dimensional Navier–Stokes equations under the Boussinesq approximation using a second-order-accurate finite-volume solver. The model was validated by reproducing experimental results for the response of a reservoir to surface shear stress and resonant frequencies of internal waves. We find interesting combinations of wave modes and mixing under variation of the forcing frequencies and of the inclination of the endwalls. When the frequency of the forcing is close to the fundamental mode-one wave frequency, a resonant internal seiche occurs and the response is characterized by the first vertical mode. For forcing periods twice and three times the fundamental period, the dominant response is in terms of the second vertical mode. Adjustment to forcing via the second vertical mode is accompanied by the cancellation of the fundamental wave and energy transfer to higher-frequency waves. The study shows that the slope of the endwalls dramatically affects the location of mixing, which has a feedback on the wave field by promoting the generation of higher vertical modes.