Judul: Rancang Bangun Alat Pengukur Percepatan Gravitasi pada Bidang Miring Berbasis Microcontroller Arduino Uno
Abstrak: Pada penelitian ini telah dilakukan pembuatan alat pengukur percepatan gravitasi pada bidang miring yang terbuat dari acrylic. Pengukuran waktu dilakukan menggunakan RTC DS1307 sebagai pengganti stopwatch. Photodioda dan LED Infra Red diletakkan di posisi awal dan akhir dari bidang miring. Sensor ultrasonik digunakan untuk mengukur ketinggian bidang miring serta sudut elevasinya. Proses pengambilan data dilakukan untuk 5 kali variasi ketinggian, masing-masing dengan 30 kali pengulangan. Hasil pengukuran menunjukkan semakin besar sudut elevasi, semakin singkat waktu yang dibutuhkan benda, sehingga percepatan semakin besar. Percepatan gravitasi rata-rata dihasilkan adalah 9.86 m/s2 dan ralat relatif percepatan gravitasi sebesar 0.5%.
Keyword: Led Infra Red, photodiode, ultrasonik

Judul: Design and Build a Room Comfort Measurement Tool (Thermal and Visual) Based on Arduino Uno
Abstrak: Perkembangan teknologi di bidang mikrokontroler yang semakin maju dan sifatnya yang opensource memudahkan pengguna dalam mengaksesnya. Penelitian ini bertujuan merancang dan membuat alat ukur kenyamanan ruangan (termal dan visual) menggunakan mikrokontroler arduino uno. Penelitian dilaksanakan pada bulan April hingga Oktober 2022 dan berlokasi di Kota Medan dan Kota Bogor. Metode yang digunakan yaitu metode kuantitatif. Alat yang dibutuhkan pada penelitian ini adalah arduino uno, sensor DHT11, sensor BH1750, breadboard, LCD, I2C, box elektronika, kabel jumper, kabel USB, solder, RTC, baut dan mur, environment meter, dan adaptor. Penelitian diawali dengan mendesain prototype pada software Proteus 8 Professional, kemudian implementasi hardware, programming, dan pengambilan data untuk keperluan kalibrasi alat. Nilai rata-rata persentase error pembacaan sensor parameter suhu, kelembaban relatif dan intensitas pencahayaan berturut-turut bernilai 1,56%; 2,95%; dan 0,76%. Sementara itu, menggunakan extension berturut-turut bernilai 1,74%; 2,73%; dan 1,31%. Hasil tersebut menunjukkan alat monitoring yang dibangun dapat beroperasi dengan baik karena nilai pembacaan mendekati sebenarnya., Technological developments in the field of increasingly advanced microcontrollers and their opensource nature make it easier for users to access them. This study aims to design and create a measuring instrument for room comfort (thermal and visual) using the arduino uno microcontroller. This research was conducted from April to June 2022 and is located in Medan City and Bogor City. The method used is quantitative method. The tools needed in this research are arduino uno, DHT11 sensor, BH1750, breadboard, LCD, I2C, electronics box, jumper cable, USB cable, soldering iron, RTC, bolts and nuts, environment meter, and adapter. The research begins with designing a prototype on the Proteus 8 Professional software, then hardware implementation, programming, and data collection for tool calibration purposes. The average percentage error of temperature sensor readings, relative humidity and lighting intensity are 1.56%, 2.95%, and 0.76%, respectively. Meanwhile, using extension is 1.74%, 2.73%, 1.31% respectively. These results indicate that the built monitoring tool can operate properly because the reading value is close to the actual.
Keyword: room comfort, arduino uno, sensor DHT11, sensor BH1750

Judul: Lejeuneaceae Subfamily Ptychanthoideae (Hepaticae) in  West Java
Abstrak: Subfamily Ptychanthoideae of the family Lejeuneaceae (Hepaticae) in West Java is still poorly known. Publications on this subfamily are out of dated and written in the 19th or early of 20th century. The last taxonomic treatment of Ptychanthoideae of West Java was in 1933, many species names have changed since then. Studies on Ptychanthoideae of West Java are urgently needed. Studies on the Ptychanthoideae were based on the specimens collected from West Java. A total number of 361 of specimens deposited in the Herbarium Bogoriense (BO), Herbarium Biotrop (BIOT), Gottingen Herbarium (GOET) and Bangi Herbarium (UKMB) were examined, those are old and several recent specimens collected in West Java. Recent collections were made from Telaga Warna, Ciater, Gunung Halimun Salak National Park, Cibodas Botanical Garden, Bodogol Education Center and Conservation (Gunung Gede Pangrango National Park), University of Indonesia Campus Depok, including several collections from Banten Province. Twenty four species of Lejeuneaceae subfamily Ptychanthoideae are known from West Java, belonging to 8 genera namely Acrolejeunea (Spruce) Schiffn. (2 species), Archilejeunea (Spruce) Schiffn. (1 species), Lopholejeunea (Spruce) Schiffn. (10 species), Mastigolejeunea (Spruce) Schiffn. (3 species), Ptychanthus Nees (1 species), Schiffneriolejeunea Verd. (1 species), Spruceanthus Verd. (2 species) and Thysananthus Lindenb. (4 species). Two new records of Ptychanthoideae: Mastigolejeunea indica Steph. and Thysananthus minor Verdoorn are reported for Java. A determination key to the species is presented including their descriptions and illustrations.
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