最近的
Experimentalphysik 6: Festkörperphysik
Dit project over tensegrities past in het thema van de Nacht van de Toren jaargang 2016. Tijdens deze openschoolnacht draait alles rond evenwicht. Tensegrities (in het Nederlands: houtje-touwtje-constructies) zijn composities met zwevende houten staafjes die elkaar niet raken maar die toch in evenwicht blijven door de gepaste trekspanning in de verbindingstouwtjes. Hoewel het assortiment aan kunstzinnige tensigrities zeer groot is, focussen we ons hier slechts op het type waarbij de staafjes een eenbladige hyperboloïde (een ruimtelichaam in de vorm van een koeltoren) afbakenen.
Some notes on combinatorics
Two Snow Plows Problem
As part of the NASA IMPACT program to model mechanical interactions with bodies in space such as comets, asteroids, and other Near Earth Objects (NEOs), the Colorado School of Mines team is designing a motor stage apparatus to interact with JSC-1A regolith simulant surfaces. This initial study involved development and testing of a prototype motor stage apparatus which was used to drive three types of probes into JSC-1A surfaces while collecting force data under standard Earth atmospheric conditions. The probes used were a conical-tipped probe, a wedge-tipped probe, and an anchoring probe. Main goals of the prototype system were to acquire general force trends for each interaction, and to isolate the most important design features for a more-complex in-vacuum system. Our data revealed force interactions that were very small in magnitude—on the order of tenths of Newtons—and more complex than our simple stiff beam probe and mount model could accurately predict. Our results lead us to recommend a more complex experimental model that can accurately represent deflection in the probes while also allowing for better measurement of regolith movement near the tip of the probes. Specifically, we recommend the following design features for the in-vacuum system: a load cell capable of measuring at very low ranges (thousandths of Newtons), reliability of structural axis alignment between trials, a robust mounting system that can accommodate each different type of probe, and consistency of sample preparation between trials.
We are asked to predict the probability of the event that a student will drop out a course. We firstly extracted many features from the huge dataset. Then we used ensemble learning machine and model stacking technique to get the final result, which ranked the 1st in 68 teams.
Notes on quadratic functions for Mathematics Standard Level (Hey Mr.Zamar)
this article is mainly to introduce R quant!
Detailed notes