Increasing the robustness of uplift modeling using additional splits and diversified leaf select

While the COVID-19 pandemic negatively affects the world economy in general, the crisis accelerates concurrently the rapidly growing subscription business and online purchases. This provokes a steadily increasing demand of reliable measures to prevent customer churn which unchanged is not covered. The research analyses how preventive uplift modeling approaches based on decision trees can be modified. Thereby, it aims to reduce the risk of churn increases in scenarios with systematically occurring local estimation errors. Additionally, it compares several novel spatial distance and churn likelihood respecting selection methods applied on a real-world dataset. In conclusion, it is a procedure with incorporated additional and engineered decision tree splits that dominates the results of an appropriate Monte Carlo simulation. This newly introduced method lowers probability and negative impacts of counterproductive churn prevention campaigns without substantial loss of expected churn likelihood reduction effected by those same campaigns

An annotated catalogue of selected Cuban piano works from the 18th-20th centuries

The piano music of Cuba encompasses a large body of valuable music that is yet to be explored fully on the international scene by performers and teachers. The purpose of this volume is to provide a guide that will enable performers and teachers to quickly reference, and more fully investigate the available music of Cuban composers. This is accomplished by providing description and levels of selected Cuban piano works from the eighteenth through twentieth centuries in catalogue format, as well as by providing descriptions of dances and dance forms found in the included literature

A Parametric Numerical Study of Mixing in a Cylindrical Duct

The interaction is described of some of the important parameters affecting the mixing process in a quick mixing region of a rich burn/quick mix/lean burn (RQL) combustor. The performance of the quick mixing region is significantly affected by the geometric designs of both the mixing domain and the jet inlet orifices. Several of the important geometric parameters and operating conditions affecting the mixing process were analytically studied. Parameters such as jet-to-mainstream momentum flux ratio (J), mass flow ratio (MR), orifice geometry, orifice orientation, and number of orifices/row (equally spaced) around the circumferential direction were analyzed. Three different sets of orifice shapes were studied: (1) square, (2) elongated slots, and (3) equilateral triangles. Based on the analytical results, the best mixing configuration depends significantly on the penetration depth of the jet to prevent the hot mainstream flow from being entrained behind the orifice. The structure in a circular mixing section is highly weighted toward the outer wall and any mixing structure affecting this area significantly affects the overall results. The increase in the number of orifices per row increases the mixing at higher J conditions. Higher slot slant angles and aspect ratios are generally the best mixing configurations at higher momentum flux ratio (J) conditions. However, the square and triangular shaped orifices were more effective mixing configurations at lower J conditions

An Analytical Study of Dilution Jet Mixing in a Cylindrical Duct

The mixing performance in a mixing section of a rich burn/quick mix/lean burn (RQL) combustor was calculated using a 3-D numerical model in a non-reacting environment. The numerically calculated results were compared with the measured data reported by Hatch, Sowa, Samuelsen, and Holdeman, 1992. The numerical 3-D temperature fields qualitatively agree with the experimental data. Also, the development of the mixing flow and temperature non-uniformity trends throughout the mixing section for the numerically calculated results quantitatively agree with the measured data. The numerical model predicts less mixing and enhances the temperature gradients as compared to the measured data for the cases reported by Hatch et al. (1992) which include circular and slot orifice shapes (with different slant angles and aspect ratios). The predicted and measured results generally agree in the selection of the slanted slot orifice configuration yielding the best overall mixing performance (based on temperature uniformity) of all the configurations analyzed

Thesen zum Ort der Musik in Peter Weirs 'The Truman Show'

Die folgenden Thesen beschränken sich auf die Frage nach dem Verhältnis von Schauspiel (Bild, Worte, Geräusche) und Musik in Peter Weirs Film

Towards More Robust Uplift Modeling for Churn Prevention in the Presence of Negatively Correlated Estimation Errors

The subscription economy is rapidly growing, boosting the importance of churn prevention. However, current true lift models often lead to poor outcomes in churn prevention campaigns. A vital problem seems to lie in instable estimations due to dynamic surrounding parameters such as price increases, product migrations, tariff launches of a competitor, or other events with uncertain consequences. The crucial challenge therefore is to make churn prevention measures more reliable in the presence of game-changing events. In this paper, we assume such events to be spatially finite in feature space, an assumption which leads to particularly bad churn prevention results if the selected customers lump in an affected region of the feature space. We then introduce novel methods which trade off uplift for reduced similarity in feature space when selecting customers for churn prevention campaigns and show that these methods can improve the robustness of uplift modeling

A low-cost airborne platform for ecological monitoring

This work documents the development of an aerial environmental monitoring platform based on a paramotor, dubbed robofoil. Significant advantages are achieved in safety, durability, ease of use and flexibility by employing an inflated wing. The aircraft is easy to fly, has near vertical ascent into wind and an intrinsic fail-safe. The ability to control the wing angle of attack and interchange wings according to weather or mission requirements makes this platform truly flexible. With an onboard autopilot and manual override, the vehicle is intuitive to fly and has a short learning curve for the user. With flight speeds ranging from 0 to 40 knots, the vehicle is well-suited to targeted surveillance as well as being resilient to gusty conditions. With a high payload capability, the platform can carry fuel for flights in excess of an hour in the current version. We have established that it is possible to use genetic programming, a machine learning technique, to evolve application-specific systems purely through training. Our eventual aim is for the design, construction details and software used for robofoil to be made fully open