Uncertainty quantification of the DTM2020 thermosphere model

Aims The semi-empirical Drag Temperature Models (DTM) calculate the Earth's upper atmosphere's temperature, density, and composition. They were applied mainly for spacecraft orbit computation. We developed an uncertainty tool that we implemented in the DTM2020 thermosphere model. The model is assessed and compared with the recently HASDM neutral density released publicly in 2020. Methods The total neutral density dataset covers all high-resolution CHAMP, GRACE, GOCE, and SWARM data spanning almost two solar cycles. We constructed the uncertainty model using statistical binning analysis and least-square fitting techniques, allowing the development of a global sigma error model to function the main variabilities driving the thermosphere state. The model is represented mathematically by a nonlinear manifold approximation in a 6-D space parameter. Results The results reveal that the altitude parameter presents the most notable error range during quiet and moderate magnetic activity ( [[EQUATION]] ). However, the most considerable uncertainty appears during severe or extreme geomagnetic activities. The comparison with density data provided by the SET HASDM database highlights some coherent features on the mechanisms occurring in the thermosphere. Moreover, it confirms the tool's relevance to provide a qualitative database of neutral densities uncertainties values deduced from the DTM2020 model.

Examination of current adsorption models for Pb(II) and Cu(II) adsorption onto Fe3O4@Mg2Al-NO3 Layered Double Hydroxide in aqueous solution

The adsorption of Pb(II) and Cu(II) onto Fe3O4@Mg2Al-NO3 Layered Double Hydroxide (LDH) as a function of Fe3O4@Mg2Al-NO3 LDH concentration was studied. An adsorbent concentration effect ( Cs effect), namely adsorption isotherm declines as adsorbent concentration ( Cs) increases, was observed. The experimental data were fitted to the adsorption models including the classic Freundlich model, the metastable-equilibrium adsorption theory, the flocculation model, the power function model, and the surface component activity model. The results show that the Freundlich-type metastable-equilibrium adsorption equation, the power function model, and the Freundlich-surface component activity equation can adequately describe the Cs effect observed in the batch adsorption tests as all the correlation coefficients ( R2) of the nonlinear plots are higher than 0.96. In other words, their intrinsic parameters simulated from the experimental data are independent of Cs value. It is considered that the Freundlich-surface component activity equation is the best model to describe the Cs effect of the studied adsorption systems by Akaike Information Criterion evaluation criterion.

Teacher to Teacher: Improving Students Mathematical Communication and Connections Using the Classic Game of “Telephone”

Remember playing the game of “Telephone” as a child? Someone whispered a statement to the person next to him or her, who then whispered to the next person in line. As each person passed the message on, everyone eagerly waited to see how it was altered and who was guilty of changing it. Our activity, “equation telephone,” was inspired by this game. Each pair or group of students is given an equation and develops a story to fit the equation. The story is passed to the next group, which, in turn, must create an equation to fit the story—not solve it, just write it. That equation is passed to the next group, which has to write another story, and so on, until the equation returns to the original group. We found that this activity greatly improved our students' ability to interpret written information and recognize equivalent forms of an equation. The following sections share the details of this activity, along with examples of student responses.