Finite Element Simulation of a Steady-State Stress Distribution in a Four Stroke Compressed Natural Gas-Direct Injection Engine Cylinder Head

The main aim of this work is to predict the design performance based on the stress/strain and thermal stress behaviour of cylinder head under various operating conditions. The effects of engine operating conditions such as combustion gas temperature and maximum internal pressure, components initial temperature and engine speed on the stress and thermal stress behaviour of the cylinder head have been analyzed. The analysis was carried out using a finite element analysis (FEA) software package, MSC.NASTRAN which is use to simulate and predict the von-Mises stress and strain pattern and thermal distribution of the cylinder head structure during the combustion process in the engine and the geometry modelling was carried out using a popular computeraided engineering tool, CATIA V5. The result can be used to determine the quality of the design as well as identify areas which require further improvement. In this investigation, structural analyses of the cylinder head highlight several areas of interest. The maximum stress is found not exceeding the material strength of cylinder head, and thus the basic design criteria, namely no yielding and no structural failure under firing load case, can be satisfied. In addition, the effect of thermal stress/strain provides a good indication on structural integrity and reliability of the cylinder head, which can be improved in the early stages of design. This steadystate finite element method (FEM) stress analysis can play a very effective role in the rapid prototyping of the cylinder head

Penerapan Energi Surya dalam Proses Termal Pengolahan Hasil Pertanian

Baru-baru ini Gustav Grob (1996) mengingatkan lagi prediksi Club of Rome di awal tahun 1970-an bahwa bahan bakar fossil, yang sifatnya meneemarkan lingkungan, dan tak terbarukan kian berkurang keberadaannya dan dalam waktu dekat harus diganti dengan sumber energi terbarukan yang lebih bersahabat dengan lingkungan seperti sumber-sumber energi surya, biomassa, angin, hidro, dll. Ketergantungan kita atas bahan bakar fosil mungkin akan berlanjut sampai beberapa dekade lagi tetapi dalam jumlah yang jauh lebih kecil dari apa yang di konsumsikan sebelum tahun 2000 seperti terlihat pada Gambar 1 (Grob, 1996

Baru-baru ini Gustav Grob (1996) Mengingatkan Lagi Prediksi Club Of Rome di Awal Tahun 1970-an Bahwa Bahan Bakar Fossil, yang Sifatnya Meneemarkan Lingkungan, dan Tak Terbarukan Kian Berkurang Keberadaannya dan dalam Waktu Dekat Harus Diganti dengan Sumber Energi Terbarukan yang Lebih Bersahabat dengan Lingkungan Seperti Sumber-sumber Energi Surya, Biomassa, Angin, Hidro, Dll. Ketergantungan Kita Atas Bahan Bakar Fosil Mungkin Akan Berlanjut Sampai Beberapa Dekade Lagi Tetapi dalam Jumlah Yang

Baru-baru ini Gustav Grob (1996) mengingatkan lagi prediksi Club of Rome di awal tahun 1970-an bahwa bahan bakar fossil, yang sifatnya meneemarkan lingkungan, dan tak terbarukan kian berkurang keberadaannya dan dalam waktu dekat harus diganti dengan sumber energi terbarukan yang lebih bersahabat dengan lingkungan seperti sumber-sumber energi surya, biomassa, angin, hidro, dll. Ketergantungan kita atas bahan bakar fosil mungkin akan berlanjut sampai beberapa dekade lagi tetapi dalam jumlah yang jauh lebih kecil dari apa yang di konsumsikan sebelum tahun 2000 seperti terlihat pada Gambar 1 (Grob, 1996

The E3i Village Concept

The E3i concept stands for empowerment the rural society in getting a better access to renewable energy sources for economic and productive activities in an environmentally sound sustainable development. This concept, proposed by the author, is meant to create the spirit of self help among the rural society who have been living in prolonged poverty and lack of access to basic energy need, especially in recent years when the price of oil becomes uncertain. Indonesia, now, is a net oil import country. Therefore, the need to tap locally available renewable energy sources is becoming an important issue. Initial works to establish the E3i village was first conducted in 1999 using the grassroots project from Japan in which several small processing units were installed in some villages in Java, Bali and West Nusa Tenggara. SPU as the value-added facilities could provide more jobs as source of income for the villagers. The paper provides more information on continuing activities in an effort to realize the E3i village concept. The importance of making use locally available renewable energy sources as the main energy input for the SPU has now gradually being appreciated by both the central and local government including the private sector

TRANSACTION COSTS AND FISHERIES CO-MANAGEMENT

Fisheries co-management as an alternative to centralized command and control fisheries management is often suggested as a solution to the problems of fisheries resource use conflicts and overexploitation. This paper highlights some elements of the transaction costs under a fisheries co-management system. The transaction costs can be categorized into three major cost items: (i) information costs, (ii) collective fisheries decision-making costs, and (iii) collective operational costs. An approach to measuring transaction costs of fisheries co-management systems both in static and dynamic processes is also proposed. There is a need to empirically evaluate the nature of the transaction costs involved in fisheries co-management institutions as a basis for evaluating the efficiency or net benefits of co-managed fisheries compared to centrally managed fisheries.Resource /Energy Economics and Policy,

PD-Fuzzy Control of Single Lower Limb Exoskeleton for Hemiplegia Mobility

This paper presents studies in the design and control of single leg exoskeleton for hemiplegia mobility in simulation environment. The exoskeleton is designed to support the affected side of the hemiplegia patient while the other leg functions normally. Hip, knee and ankle joints for both humanoid leg and exoskeleton of the affected side are controlled using PD-Fuzzy control to obtain the required natural torque to allow the exoskeleton to compensate for the deficiency in affected leg to achieve normal symmetric gait. The controller is implemented in MATLAB, and the system behaviour observed in Visual Nastran 4D (VN4D) during simulation. Simulation results show that the exoskeleton can support the humanoid with the required augmentation using the proposed design and control

PENGARUH UKURAN PERUSAHAAN, PROFITABILITAS, DAN LEVERAGE TERHADAP PENETAPAN TINGKAT DISKONTO DALAM ADOPSI METODE EKUITAS

This study aims to obtain empirical evidence of the effect of firm size, profitability, and leverage on the determination of the discount rate when the adoption of equity method. Firm size is measured by using natural logarithm of total company asset, Profitability is measured by Return on Equity (ROE), and Leverage is measured by Debt to Equity (DER). The discount rate is measured by the discount rate set by the company. The population in this study is a company listed Indonesia Stock Exchange during the year 2015-2016. The research data is obtained from the company's financial report on Bursa Effek Indonesia during the year 2015-2016. Pursuant to purposive sampling method, the sample obtained as many as 208 companies during 2015-2016. The hypothesis in this study was tested using multiple regression. The result of firm size analysis has negatif and not significant influence to the determination of discount rate and profitability and leverage analysis has positif and significant effect on the determination of discount rate at the time of adoption of equity method

Flipping Learning to Develop Students' Engagement and Achievement in the Computer Applications Unit as Part of Their Studies on the Sub-ject of Instructional Design

The study aimed to measure the impact of using the flipped learning strategy on students’ engagement and achievement when creating computer applications. The study used a quasi-experimental approach to prepare the literature framework and two measurement tools, including an achievement test and an engagement scale. The study sample consisted of 42 learners. The researcher used a t-test to measure the differences between the control group (taught by a traditional method) and experimental group (taught using the flipped learning strategy). The content of the pre-class consisted of videos, PowerPoint presentations and the use of appropriate URLs, which was provided through an Easy class platform. Students worked individually and cooperatively during the class activities. The results showed that there were statistically significant differences at α≤0.05 between the means of the experimental and control groups in the post-tests on both achievement and learning engagement. This was in favor of the experimental group, which used videos, presentations and web links on the subject of achievement and learning engagement, unlike the control group that used a traditional method