PENGUJIAN KARATERISTIK PENGISIAN BATERAI DARI GENERATOR DC MAGNET PERMANEN MENGGUNAKAN SOLAR CHARGING CONTROLLER

Penelitian ini melakukan pengujian karateristik pengisian baterai yang menggunakan generator DC magnet permanen sebagai sumber, dan pengaturan pengisian baterai menggunakan Solar Charging Controller (SCC) yang sering dipakai sebagai pengatur pengisian dari panel surya. Pengujian ini dilakukan untuk mengetahui nilai tegangan dan rpm minimal generator agar baterai dapat terisi. Pelaksanaan pengujian dilakukan menggunakan generator DC magnet permanen dengan kapasitas 250 watt, 24 Volt, pada putaran 2750 rpm. Genarator ini dihubungkan ke SCC untuk mengatur pengisian baterai VRLA 12 Volt 7 Ah, dan beban lampu 12 Volt 5 Watt sebanyak 20 buah. Sebagai penggerak mula, digunakan motor induksi 3 fasa yang putarannya dapat diatur melalui Variable Speed Drive (VSD). Parameter arus dan tegangan dari masing-masing generator, baterai, dan beban lampu akan diamati. Untuk mengetahui putarang generator, rpm meter digunakan untuk mengetahui putaran generator. Dari hasil pengujian diperoleh bahwa tegangan minimum generator agar dapat mengisi baterai adalah 12.3 Volt pada putaran 1630 rpm.

On modules of finite projective dimension

We address two aspects of finitely generated modules of finite projective dimension over local rings and their connection in between: embeddability and grade of order ideals of minimal generators of syzygies. We provide a solution of the embeddability problem and prove important reductions and special cases of the order ideal conjecture. In particular, we derive that, in any local ringRof mixed characteristicp> 0, wherepis a nonzero divisor, ifIis an ideal of finite projective dimension overRandp𝜖Iorpis a nonzero divisor onR/I, then every minimal generator ofIis a nonzero divisor. Hence, ifPis a prime ideal of finite projective dimension in a local ringR, then every minimal generator ofPis a nonzero divisor inR.

On modules of finite projective dimension

We address two aspects of finitely generated modules of finite projective dimension over local rings and their connection in between: embeddability and grade of order ideals of minimal generators of syzygies. We provide a solution of the embeddability problem and prove important reductions and special cases of the order ideal conjecture. In particular, we derive that, in any local ring R of mixed characteristic p > 0, where p is a nonzero divisor, if I is an ideal of finite projective dimension over R and p 𝜖 I or p is a nonzero divisor on R/I, then every minimal generator of I is a nonzero divisor. Hence, if P is a prime ideal of finite projective dimension in a local ring R, then every minimal generator of P is a nonzero divisor in R.

On the Calculation of Formal Concept Stability

The idea of stability has been used in many applications. However, computing stability is still a challenge and the best algorithms known so far have algorithmic complexity quadratic to the size of the lattice. To improve the effectiveness, a critical term is introduced in this paper, that is, minimal generator, which serves as the minimal set that makes a concept stable when deleting some objects from the extent. Moreover, by irreducible elements, minimal generator is derived. Finally, based on inclusion-exclusion principle and minimal generator, formulas for the calculation of concept stability are proposed.

An Analytical Survey of Current Approaches to Mining Logical Rules from Data

An analytical survey of some efficient current approaches to mining all kind of logical rules is presented including implicative and functional dependencies, association and classification rules. The interconnection between these approaches is analyzed. It is demonstrated that all the approaches are equivalent with respect to using the same key concepts of frequent itemsets (maximally redundant or closed itemset, generator, non-redundant or minimal generator, classification test) and the same procedures of their lattice structure construction. The main current tendencies in developing these approaches are considered.