Petra Christian University

About: Petra Christian University is a education organization based out in Surabaya, Indonesia. It is known for research contribution in the topics: Population & Customer satisfaction. The organization has 2412 authors who have published 2893 publications receiving 10429 citations.

Kriging-Based Timoshenko Beam Elements with the Discrete Shear Gap Technique

Abstract: Kriging-based finite element method (K-FEM) is an enhancement of the FEM through the use of Kriging interpolation in place of the conventional polynomial interpolation. In this paper, the K-FEM is ...

Deriving Conceptual Schema from XML Databases

Abstract: In this paper, two concepts from different research areas are addressed together, namely functional dependency (FD) and multidimensional association rule (MAR). FD is a class of integrity constraints that have gained fundamental importance in relational database design. MAR is a class of patterns which has been studied rigorously in data mining. We employ MAR to mine the interesting rules from XML Databases. The mined interesting rules are considered as candidate FDs whose all confidence itemsets are 100%. To prune the weak rules, we pay attention to support and correlation itemsets. The final strong rules are used to generate an Object-Role Model conceptual schema diagram.

Potensi pemakaian kerikil paterongan torjun dan omben di pulau madura untuk beton struktur

Abstract: The use of structural concrete in Madura increases with the development of the island, however coarse and fine aggregates which are used, mostly come from Jawa. This research explores the possibility of using the coarse aggregates from Madura taken from Paterongan, Torjun, and Omben. Although it is shown that in general the coarse aggregates are physically the same with aggregates from Mojokerto or Pasuruan and pass SNI, ACI, ASTM, and BS, only aggregate from Torjun pass the flakiness requirements. The fineness modulus of the aggregates do not pass SNI but pass the BS requirement. Using the aggregates in 225kg/cm2 concrete strength mix design fail to reach the target strength. Aggregates from Paterongan and Omben are only recommended for lean concrete, but there is a possibility to use aggregates from Torjun for structural concrete, with betterment in grading. Abstract in Bahasa Indonesia : Pemakaian beton di pulau Madura meningkat seiring dengan perkembangan pulau Madura tetapi agregat kasar dan halus yang digunakan untuk pembuatan beton masih banyak didatangkan dari pulau Jawa. Untuk melihat kemungkinan penggunaan krikil Madura sebagai agregat kasar beton, telah dilakukan penelitian kekuatan terhadap kerikil Madura yang berasal dari Paterongan, Torjun, dan Omben. Meskipun secara umum dapat dikatakan sifat-sifat fisik kerikil tersebut mendekati sama dengan kerikil dari Mojokerto atau Pasuruan dan memenuhi syarat SNI, ACI, ASTM maupun BS, hanya krikil dari Torjun yang memenuhi syarat kepipihan. Modulus kehalusan kerikil tersebut juga tidak memenuhi syarat SNI walaupun masih memenuhi syarat BS. Penggunaan kerikil Paterongan, Torjun, dan Omben untuk mix disain 225 kg/cm2 ternyata di bawah target yang diharapkan, sehingga kerikil Paterongan dan Omben direkomendasi hanya untuk beton rabat, sedangkan kerikil dari Torjun kemungkinan masih bisa digunakan untuk beton struktur dengan perbaikan gradasi.

Combustion Characteristics Behavior of Pterocarpus indicus Leaves Waste Briquette at Various Particle Size and Pressure

Abstract: As one of the countries with a high variety of plant species, Indonesia becomes a potential source for biomass fuel. One plant that commonly found in the street of Surabaya, Indonesia is Pterocarpus indicus. The plant exists in large number and produced litters from its leaves waste. The litters negatively affect Surabaya city cleanliness. The previous study suggested a solution for this problem is by converting these litters into biomass fuel in the form of briquette. The solution may help this problem by reducing the wastes in Surabaya street and avoiding unnecessary handling of these wastes by burning or burying. In order to maximize the potential of Pterocarpus indicus leaves waste briquette, two primary parameters of briquette production were investigated in this study. These parameters are particle size of briquette and pressure used for compacting the briquette. This study used four burning characteristics (flame temperature, ignition time, burning time and combustion rate) to determine the best particle size and pressure to obtain the highest quality of briquette. The result of the study indicates Pterocarpus indicus produced with particle size of 60 mesh and compacting pressure of 2 MPa yield the best quality of briquette.

Symbiotic organisms search with the feasibility-based rules for constrained engineering design optimization

Abstract: During the past decades, metaheuristic algorithms have been utilized to deal with constrained optimization with a high degree of success. Recently, symbiotic organisms search (SOS), a promising and new metaheuristic algorithm, has gained increased attention due to its excellent performance in solving many complex problems. This paper incorporates SOS with the feasibility-based rules for solving constrained engineering design problems. The feasibility-based rules were integrated to SOS in order to satisfy the design constraints of each problem. The performance of SOS was compared with the performance of recent optimization algorithms in solving three engineering design problems. The experimental results reveal the potential of the proposed algorithm to deliver solutions at better quality using a smaller number of function evaluations. Results indicate that SOS efficiently solves various complex problems using an approach that is simpler to implement than current widely used methods.