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.

Effect of Cerbera Manghas Biodiesel on Diesel Engine Performance

Abstract: In order to reduce the use of fossil fuel without interfering the availability of food crop, Cerbera manghas biodiesel has been studied as potential renewable fuel. This study investigated Cerbera manghas biodiesel as a replacement for pure petro-diesel and palm oil biodiesel produced in Indonesia. The investigation result indicates that Cerbera manghas biodiesel fuel has a lower density, kinematic viscosity, sulfur content, color (lighter), water content, distillation point compared to pure petro-diesel and palm oil biodiesel. Higher flash point and cetane index value in Cerbera manghas biodiesel were also discovered. The study investigated further the effect of biodiesel derived from Cerbera manghas biodiesel compared with pure petro-diesel and palm oil biodiesel in a single cylinder diesel engine. The study suggested that Cerbera manghas biodiesel has better engine performance (fuel consumption, brake mean effective pressure, thermal efficiency, torque, and power) compared to pure petro-diesel and palm oil biodiesel. The utilization of Cerbera manghas biodiesel gave better engine performance output compared to pure petro-diesel and palm oil biodiesel. This study supported the viability of Cerbera manghas biodiesel to be implemented as an alternative diesel fuel without interfering food resources or requiring additional modification to the existing diesel engine.

Pengaruh risiko sistematis dan likuiditas terhadap tingkat pengembalian saham badan-badan usaha yang go-public di bursa efek jakarta pada tahun 1999

Abstract: Research on determinant variables of rate of return has frequently been undertaken%2C generally with the conclusion that stock risk is very dominant for an investor in making investment decisions in the capital market. But there is another factor that also needs to be considered%2C stock liquidity.%0D%0AThe purpose of this research is to test how systematic risk and stock liquidity%2C measured by the size of the spread between the bid and asked prices%2C influence stock returns of public companies listed on the Jakarta Stock Exchange and to know proportion of each variable%5C%27s influence on the return of individual stocks.%0D%0AThe results from this study show that systematic risk and stock liquidity%2C measured by the size of the spread between the bid and asked prices%2C had a significant effect on the return of individual stocks of public companies in Indonesia. Hypothesis tests for each variable showed that systematic risk had a greater effect on returns than stock liquidity. Abstract in Bahasa Indonesia : Penelitian mengenai variabel-variabel penentu tingkat pengembalian saham yang banyak dilakukan umumnya selalu menyimpulkan bahwa risiko saham sebagai salah satu variabel penentu sangat mendominasi dalam setiap pertimbangan yang dilakukan oleh para investor dalam memutuskan untuk menginvestasikan dananya di pasar modal. Namun sebenarnya ada variabel penentu lain yang juga akan mempengaruhi tingkat pengembalian saham yang perlu dipertimbangkan pula%2C yaitu likuiditas saham. %0D%0ATujuan dari penelitian ini adalah untuk menguji bagaimana pengaruh risiko saham dalam hal ini adalah risiko sistematis dan likuiditas saham yang diukur dengan besarnya bid-ask spread terhadap tingkat pengembalian saham dari badan-badan usaha yang go public di PT.BEJ%2C dan untuk mengetahui seberapa besar proporsi masing-masing variabel dalam mempengaruhi tingkat pengembalian saham.%0D%0AHasil akhir dari penelitian ini menunjukkan bahwa baik risiko sistematis maupun likuiditas saham yang diukur dengan besarnya bid-ask spread mempunyai pengaruh yang signifikan terhadap tingkat pengembalian saham dari badan-badan usaha yang go public di Indonesia. Dari uji hipotesis didapatkan hasil bahwa risiko sistematis lebih mempengaruhi tingkat pengembalian suatu saham dibandingkan dengan likuiditas saham yang diukur dengan besarnya bid-ask spread. systematic+risk%2C+stock+liquidity%2C+bid-ask+spread%2C+stock+return.

Respon pendopo joglo yogyakarta terhadap getaran gempa bumi

Abstract: After May 2006 earthquake the two Pendopo Joglo buildings in Yogyakarta, as displayed in figure 1A and 1B, were showed different failures. In Pendopo Joglo 1A, the sokoguru was broken right under the sunduk kili causing the building to collapse. On the other hand, in Pendopo Joglo 1B case, the sakaguru was slipped but still remained on its position on the umpak so the building did not collapse. The structure differences between the two buildings were the support system used for each building. Pendopo Joglo 1A used pen and hole in the sokoguru base to act as pin joint support, while in Pendopo Joglo 1B, the sokoguru was only placed on the umpak, so it could slip if the earthquake shook it. The slip (as in 1B case) restrained the earthquake vibration as could be learned in base isolator technology. This writing is not a study based on field observation but an analysis about the two buildings different responses to the earthquake vibration which was caused by the different support character. This analysis is based on Static Equivalent Earthquake Load Analysis and is using qualitative method. Abstract in Bahasa Indonesia: Dua buah bangunan Pendopo Joglo di Yogyakarta pada gambar 1A dan 1B mengalami kerusakan berbeda setelah kejadian gempa bumi bulan Mei 2006. Pada Pendopo Joglo 1A sokoguru patah tepat dibawah sunduk-kili dan bangunan runtuh, sedangkan pada pendopo joglo 1Bsokoguru bergeser posisinya pada tumpuan umpak, tapi bangunan tidak runtuh. Perbedaan struktur kedua bangunan terletak pada sistem tumpuannya, yaitu Pendopo Joglo 1A menggunakan tumpuan sendi berupa pen dan lubang di kaki sokogurunya, sedangkan pada pendopo joglo1B sokoguru hanya diletakkan diatas umpak sehingga dapat bergeser apabila digetarkan gempa. Pergeseran ini memberikan sifat meredam getaran gempa yang dapat dipelajari dari teknologi base-isolator. Tulisan ini bukan sebuah penelitian yang didasarkan pada fakta lapangan, tapi berisi analisis tentang perbedaan respon kedua bangunan terhadap getaran gempa akibat adanya perbedaan sifat tumpuan. Analisis dalam tulisan ini didasarkan pada analisis beban gempa statik ekivalen (2) dan dibahas secara kualitatif Kata kunci: gempa, Pendopo Joglo, sistem tumpuan, repon struktur, peredaman.

Is Green Concept in Residential Expensive

Abstract: A house, especially landed housing is one of the primary needs and yet scarcity continues to occur due to the depletion of land quantity and increasingly rising selling prices. In order for the development of a residential area to be more directed and productive, it is necessary to analyze the appropriate land allocation and generate maximum land value. Through this paper, the author examines the effect of a residential planning with green concepts along with housing support facilities in relevance with highest and best use analysis, especially its impact on costs and revenues.

A Comparative Study on Bio-Inspired Algorithms in Layout Optimization of Construction Site Facilities

Abstract: A good arrangement of site layout on a construction project is a fundamental component of the project’s efficiency. Optimization on site layout is necessary in order to reduce the transportation cost of resources or personnel between facilities. Recently, the use of bio-inspired algorithms has received considerable critical attention in solving the engineering optimization problem. These methods have consistently provided better performance than traditional mathematical-based methods to a variety of engineering problems. This study compares the performance of particle swarm optimization (PSO), artificial bee colony (ABC), and symbiotic organisms search (SOS) algorithms in optimizing site layout planning problems. Three real-world case studies of layout optimization problems have been used in this study. The results show that SOS has a better performance in comparison to the other algorithms. Thus, this study provides useful insights to construction practitioners in the industry who are involved in dealing with optimization problems