PENGARUH MODEL PROBLEM BASED LEARNING TERHADAP KEMAMPUAN KOMUNIKASI MATEMATIS SISWA

This study aims to determine the effect of a problem-based learning model on student’s mathematical communication skills. The population was all students of grade VIII SMP Negeri 19 Bandarlampung odd semester in the academic year 2019/2020 that were distributed into ten classes. The research samples were all students of grade VIII E and VIII F which were selected through a purposive sampling technique. The posttest only controls group design was used as the design of this research. The research data analysis using U-test at a significant level  = 0.05, students’ communication skills with the problem-based learning model are significantly higher than students’ communication skills with conventional learning. Conclusions are obtained that the problem-based learning model was an effect on student’s mathematical communication skills.Keywords: mathematical communication skills; problem-based learning; students DOI: http://dx.doi.org/10.23960/mtk/v8i2.pp182-19

Pengaruh Variasi Temperatur Sintering Dan Waktu Tahan Sintering Terhadap Densitas Dan Kekerasan Pada Mmc W-Cu Melalui Proses Metalurgi Serbuk

Proyektil adalah bagian dari peluru yang dioptimalkan agar peluru memiliki jangkauan dan daya tembus yang tinggi.Untuk itu material yang biasa digunakan adalah material yang memiliki densitas yang tinggi seperti timbal.Namun, timbal memiliki tingkat kontaminasi yang tinggi. Oleh karena itu, dalam penelitian ini akan dibuat komposit W-Cu (Tungsten-Copper) sebagai material alternatif untuk core proyektil. Pembuatan dilakukan dengan proses metalurgi serbuk dengan komposisi fraksi berat 70%W dan 30%Cu serta tekanan kompaksi 400 MPa. Sedangkan temperatur sintering dan waktu tahan sintering dilakukan dengan beberapa variasi yaitu 700, 800, 900°C dan 1,2,3 jam, secara berturut-turut. Untuk mengidentifikasi digunakan beberapa pengujian seperti uji densitas, uji kekerasan, SEM, XRD dan uji tekan. Berdasarkan hasil pengujian, fasa yang terbentuk dari hasil XRD adalah W dan Cu, sinter density tertinggi sebesar 12.78 g/cm3 dan porositas terkecil sebesar 10.82% pada 900°C-2 jam, kekerasan tertinggi sebesar 34.7 HRb pada 900°-2 jam, kekuatan tekan tertinggi sebesar 156.71 MPa pada 800°C-3 jam, modulus elastisitas tertinggi sebesar 50.23 GPa pada 800°C-3 ja

Water Quality Characteristics of Jonge Telaga (Doline Pond) as Water Resources for the People of Semanu District Gunungkidul Regency

Abstract Doline ponds (telaga) have an important role as one of water resources in karst areas, especially during dry seasons in Gunungkidul. Recently, the doline ponds are facing various environmental problems, i.e. steadily decreasing water storage, water loss, and degrading water quality. The research aims to determine the characteristics of Jonge Telaga which include the continuity of flow, utilization, pollution sources, physical water quality (temperature, EC,TDS, TSS, and turbidity), chemical water quality (pH , NO2, NO3, NH4, PO4, BOD , COD, and detergent), and biological water quality (total coliform). In order to determine the characteristics of Jonge Telaga, the research was conducted using a survey method, i.e., observing the continuity of flow and measuring physical, chemical, and biological water quality. Initially, the water was sampled purposively based on the area and the depth of this doline pond. The qualitative description of the results shows that Jonge Telaga is a closed perennial doline pond, whose main pollution source comes from domestic activities, such as bathing and washing. According to the Governor Regulation of the Special Region of Yogyakarta Number 20 Year 2008 on Water Quality Standards, Jonge Telaga meets all of the water quality criteria, except the temperature and detergent, for a Class II water.Abstrak Telaga mempunyai peran penting sebagai salah satu sumberdaya air di daerah karst, khususnya pada musim kemarau di Kabupaten Gunungkidul. Pada saat ini telaga menghadapi berbagai permasalahan lingkungan yaitu simpanan air yang terus berkurang, air yang cepat hilang, dan penurunan kualitas air. Tujuan penelitian adalah untuk mengetahui karakteristik telaga yang meliputi kontiyuitas aliran, pemanfaatan, sumber pencemar, kualitas fisik air telaga (TDS, TSS, suhu, kekeruhan, DHL), kimia air (pH, NH4, PO4, NO2, NO3, BOD, COD, deterjen) dan biologi air (coliform total).  Penelitian ini dilaksanakan berdasarkan metode survei. Untuk mengetahui karakteristik telaga dilakukan pengamatan kontinyuitas aliran, pengukuran kualitas air secara fisik, kimia dan biologi. Pengambilan sampel air dilakukan secara purposive mendasarkan pada luasan dan kedalaman telaga. Analisis hasil dilakukan secara deskriptif kualitatif. Hasil penelitian menunjukkan bahwa Telaga Jonge merupakan telaga yang tertutup dengan ketersediaan air menerus sepanjang tahun. Sumber pencemar utama telaga adalah kegiatan domestik (mandi dan cuci). Kualitas air Telaga Jonge menurut baku mutu air kelas II PERGUB DIY Nomor 20 Tahun 2008 masih di bawah ambang batas kecuali suhu dan deterjen

Pengaruh Perilaku Penduduk Dalam Membuang Limbah Terhadap Kualitas Air Sungai Gajahwong (the Influence of People Behaviour in Disposing Waste to the Gajahwong Water Quality)

Gadjahwong river is one of “Prokasih” (Clean River Program) targets, and the water has been planned as B category. The objectives of the research include (1) to identify the water quality, (2) to identify pollutant sources, (3) to understand the people behavior related to the river, (4) to identify the relationship between the people behavior and the river water quality. Data about water use in this research were collected using sampling method, while socio-economics data were compiled through the Rapid Rural Appraisal approach. The result show that there is a relationship between water quality and people behavior. Potential pollutants in the upper stream include house hold waste, agriculture. In the middle and lower streams include agriculture, settlement, and industry

Kajian Kualitas Limbah Cair Industri Pupuk PT. Pupuk Kalimantan Timur

Penelitian ini bertujuan untuk mengetahui nilai beban pencemar dan karakteristik limbah cair yang dihasilkan oleh unit produk pabrik K1, K2, K3, K4, dan POPKA serta untuk mengetahui kualitas air laut dan persebaran nilai kualitas air laut tersebut di sekitar outfall pabrik. Penelitian ini menggunakan 5 sampel limbah cair dan 27 sampel air laut. Hasil penelitian menunjukan parameter kualitas air limbah secara keseluruhan telah memenuhi baku mutu. Hasil penelitian berdasarkan parameter kualitas air laut NH3-N pada seluruh titik pemantauan nilainya belum memenuhi baku mutu. Parameter suhu air laut pada lokasi dekat dengan outfall nilainya masih di bawah baku mutu. Parameter pH air laut di sekitar outfall pabrik secara keseluruhan nilainya telah memenuhi baku mutu

Peningkatan Produksi Lapangan “M” Dengan Pendekatan Simulasi Untuk Menentukan Skenario Pengembangan Menggunakan Metode Waterflooding

Reservoir simulation is an area of reservoir engineering in which computer models are used to predict the flow of fluids through porous media. Reservoir simulation process starts with several steps; data preparation, model and grid construction, initialization, history matching and prediction. Initialization process is done for matching OOIP or total initial hydrocarbon which fill reservoir with hydrocarbon control volume with volumetric method.To aim the best encouraging optimum data, the plant of developments of this field was predicted for 22 years( until December 2035). The Scenario consisted of five different variation. First one is basecase, second scenario is scenario 1 + workover, third scenario would be scenario 1 + infill wells, fourth scenario is scenario 1 + peripheral injection, and the last fifth scenario is scenario 1 + 5-spot injection pattern wells. From all of the scenarios planned, recovery from from each scenario varied, the results are 31.05% for the first scenario, 31.53%, for the second one, 34.12%, for the third, 33.75% for the fourth scenario, and 37.04% for the fifth scenario which is the last one