Heru Tjahjana
Diponegoro University

Published : 5 Documents
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SOLVING A SYSTEM OF LINEAR EQUATIONS BY QR FACTORIZATION METHOD FOR TEMPERATURE AND ALTITUDE REGRESSION MODEL AGAINST SPONTANEOUS-POTENTIAL Widowati, Widowati; Setyawan, Agus; Mustafid, Mustafid; Nur, Muhammad; Sudarno, Sudarno; Harmoko, Udi; Adhy, Satriyo; Gunawan, Gunawan; Subagio, Agus; Tjahjana, Heru; Sulpiani, Ririn; Riyanto, Djalal Er; Suhartono, Suhartono; Mukid, Mochammad Abdul; Suseno, Jatmiko Endro
JURNAL SAINS DAN MATEMATIKA Volume 22 Issue 3 Year 2014
Publisher : JURNAL SAINS DAN MATEMATIKA

#### Abstract

Many real problems can be represented in the form of multiple linear regression equation. One of those is the relationship between the variables of temperature and altitude of the spontaneous-potential. In order to determine the parameters of the regression equation, the least squares method was used. From here, there was obtained the system of linear equations. In this paper, to solve systems of linear equations, the exact method was used as the exact solution is certainly better than the approached solution. The method used was the QR factorization method. At the QR factorization, the system of linear equations was written in form of matrix equation. Then, the coefficient matrix which the number of rows is m and number of columns is n with linearly independent columns was factored into the matrix Q which has the same size with the matrix A, with orthonormal columns and matrix R was upper triangular. Furthermore, by backward substitution, it could be obtained the exact solution of linear equation system. As verification of this proposed method, a case study was given using data of temperature, altitude, and spontaneous-potential in the geothermal manifestations area, Gedongsongo, Mount Ungaran Semarang. From here, it was obtained the parameters of exact multiple linear regression model which states the relationship between temperature and altitude toward the spontaneous-potential.
Jurnal Matematika Vol 2, No 1 (2013): JURNAL MATEMATIKA
Publisher : MATEMATIKA FSM, UNDIP

#### Abstract

Pengaruh Penggunaan Binder terhadap Densitas dan Kalor Pembakaran Briket dari Limbah Sagu Widiyandari, Hendri; Setiabudi, Wahyu; Subagio, Agus; Haryanti, Sri; Siahaan, Parsaoran; Tjahjana, Heru
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 3, No 02 (2013): IJAP VOLUME 03 ISSUE 02 YEAR 2013
Publisher : Department of Physics, Sebelas Maret University

#### Abstract

Biomass fuel such as briquette is one of an alternative energy regarded to the shortage of theÂ fosil fuel and rising its prices. The byproduct of sago starch industry is the waste that remainÂ the environmental problem because of the odor. However this agricultur waste such as trunkÂ cortex and fibre has a potential application as a raw material for briquette.The fibre and trunkÂ cortex act as matrix material of briquette. The utilizing of sago waste as a biomass briquetteÂ and the effect of ratio of matrix/binder to the density, time of compustion and gross heat ofÂ the briquette have been elucidated sistematically. The analyzing of gross heat using adiabaticÂ calorimetry indicated that the briquette prepared with the ratio of binder/matrix of 3:4 (massÂ ratio) had the maximum value of 3929.5 kal/g. The duration of combusion was proposionalÂ with density of the briquette.
PELABELAN TOTAL SUPER TRIMAGIC SISI PADA BEBERAPA GRAF Utomo, R. Heri Soelistyo; Tjahjana, Heru; Irawanto, Bambang; Ratnasari, Lucia
Journal of Fundamental Mathematics and Applications (JFMA) Vol 1, No 1 (2018): Journal of Fundamental Mathematics and Applications
Publisher : Department of Mathematics, Faculty of Science and Mathematics, Diponegoro University