Abstract: The use of Energy that is in accordance with the planned can be said to be effective and efficient, only can be known through the activities of what is called the Energy Audit. The Energy Audit can be passed in two stages, namely the initial energy audit and detailed energy audit. Initial energy audits are usually carried out on existing data without being inputted with system measurement activities. Detailed energy audits are carried out through the stages of measuring inputs and outputs on energy components and utilities such as refrigeration, lighting, transport utilities and energy users' equipment, both electricity and other types of energy. By referring to the Indonesian National Standard, what energy use can be said to be efficient or not. From the activity of this energy audit it is known that the Energy Consumption Index in buildings is = 19 kWh / m / month or = 228 kWh / m2 / year; according to the Standard classified as Quite efficient., it is known that the profile of energy use that gives a description of the percentage of utility in consuming energy, then it can be known that energy-saving opportunities to be considered are then a priority for implementing energy saving projects.

Abstract: Failures experienced by wireless sensor networks could result in a range of consequences from mild annoyance, lost fortunes, environmental disaster to significant injury or even loss of lives. It is therefore important to ensure that sensor networks continue to carry out their intended purpose despite a failure of a single node or a portion of the network. In this paper, fault tolerance, reliability and availability issues for wireless sensor networks are explored. A Fault Tolerant (FT) triplex sensor node Markov model following a corrective maintenance strategy where a repair action is initiated to bring a failed sensor node back to its operating state was proposed. Using Markov process theory, Laplace transforms and limiting state probability evaluation, the explicit expressions of the Mean Time to Failure (MTTF) and Steady-State Availability (SSA) of the model was derived analytically. It was observed that the proposed FT triplex sensor node Markov model provide significant MTTF and SSA improvements over a Non-Fault Tolerant system. The results revealed that from a reliability point of view, the FT Sensor Node Markov model with speedup shared repair is dominant, while for availability, the FT Sensor Node Markov model with independent repair is preferred. Sensitivity analysis of the MTTF and SSA characteristics of the optimal models with respect to the system parameters were performed. It was illustrated that the MTTF and SSA indexes are very sensitive to changes in the system parameters.

Abstract: In this paper, the effect of different types of edge shape design preparations on the microstructure and mechanical property of shielded metal arc welded (SMAW) low carbon steel joints is investigated. Four different edge shape designs are discussed, namely; straight, single V, double V and single groove edge, selected to weld 12 mm low carbon steel plate. The samples were cut through the cross-section area of the welded joint and metallographically prepared for observation under optical microscopy. The cross section area of the welded joint consists of three main areas, namely the base metal (BM), heat affected zone (HAZ), and weld metal (WM). Micro-hardness (Hv1) test were performed at room temperature by using Vickers micro- hardness tester. The results show that the highest hardness value was found at the HAZ area, followed by the base metal and weld metal areas. Based on microstructure analyses, it was found that the HAZ area is divided into three zone; coarse grained zone (CGHAZ), fine grained zone (FGHAZ) and inter-critical grained zone (IGHAZ) which results in high hardness compared with the rest of the metal.