Development of Plants Morphology Characteristics Textbook to Improve Students' Ability in Identifying Plants

The selection and use of appropriate textbooks in the lecture process is an important factor for improving science process skills. This study aims to develop textbooks on plant morphological characteristics that are valid, practical, and effective in increasing students' ability to identify plants. The method used is research and development with a design Plomp model which consists of five stages in the form of (1) initial investigation, (2) design, (3) realization, (4) testing, evaluation, and revision, (implementation). The subjects of this study were students who took plant anatomy and morphology courses, the academic year 2020/2021 of the STKIP Soe Biology education study program. Data collection techniques in the form of observation, tests, and questionnaires. The product in the form of a textbook developed was tested for validity based on the research results of the expert team as a validator. The practicality of the product was tested using a student and lecturer response questionnaire analysis. The textbook effectiveness test was carried out through quasi-experimental research with analytical techniques using an independent sample T-test and normalized gain scores. The results showed that the textbooks developed were valid, practical, and effective to improve students' ability to identify plant species

Optimal two-impulse rendezvous using multiple revolution Lambert’s solutions

The minimum-¢V, � xed-time, two-impulse rendezvous between two spacecraft orbiting along two coplanarunidirectional circular orbits (moving-target rendezvous) is studied. To reach this goal, the minimum-¢V, � xed-time, two-impulse transfer problem between two � xed points on two circular orbits is � rst solved. This � xed-endpoint transfer is related to the moving-target rendezvous problem by a simple transformation. The � xed-endpoint transfer problem is solved using the solution to the multiple-revolution Lambert problem. A solution procedure is proposed based on the study of an auxiliary transfer problem. When this procedure is used, the minimum ¢V of the moving-target rendezvous problem without initial and terminal coasting periods is obtained for a range of separation angles and times of � ight. Thus, a contour plot of the cost vs separation angle and transfer time is obtained. This contour plot, along with a sliding rule, facilitates the task of � nding the optimal initial and terminal coasting periods and, hence, obtaining the globally optimal solution for the moving-target rendezvous problem. Numerical examples demonstrate the application of the methodology to multiple rendezvous of satellite constellations on circular orbits