The Evaluation of Failure Structure Condition with Plaxis Program on the Poso I Hydropower Barrage

The Poso I Hydropower Station is located on the Poso River, at the downstream section of the Poso Lake in Central Sulawesi Province. At the weir site, the catchment area is 1906.30 km2, and the structures are designed for a 50 year return period. Flood discharge is 1456.50 m3/s, with the mean annual release being 127.85 m3/s. The total supply water level is 510.50m, and the minimum operating level is 506.00 m. The model uses an undistorted model with a scale of 1 to 60. The barrage needs to be reviewed for failure factors that are likely to occur similar to those used in potential failures in the construction of dams in general. The study was considered in three conditions: empty barrage condition, average level, and flood level. With the piping calculation method, the barrage used Lane and Bligh method. While the calculation of barrage sliding stability used Finite Element Method with Plaxis 2D program simulation got the safety factor at the empty condition and flood level. It is caused by water pressure at flood level conditions that influence barrage stability. Safety factor value exceeded permits made. The Poso I Hydropower Station was safe.

The Deltah Lab, a New Multidisciplinary European Facility to Support the H2 Distribution & Storage Economy

The target for European decarburization encourages the use of renewable energy sources and H2 is considered the link in the global energy system transformation. So, research studies are numerous, but only few facilities can test materials and components for H2 storage. This work offers a brief review of H2 storage methods and presents the preliminary results obtained in a new facility. Slow strain rate and fatigue life tests were performed in H2 at 80 MPa on specimens and a tank of AISI 4145, respectively. Besides, the storage capacity at 30 MPa of a solid-state system, they were evaluated on kg scale by adsorption test. The results have shown the H2 influence on mechanical properties of the steel. The adsorption test showed a gain of 26% at 12 MPa in H2 storage with respect to the empty condition. All samples have been characterized by complementary techniques in order to connect the H2 effect with material properties.

A study on damping ratio of EPS foam filled CFRP composite tubes

This study aims to investigate the damping behavior of the fundamental mode of a foam-filled carbon fibre reinforced polymer composite (CFRP) tube when subjected to base excitations. In particular, expanded polystyrene (EPS) foam balls (with negligible mass) of different sizes are used as fillers in the tube and the enhancement in damping ratio of the fundamental mode w.r.t the empty condition is evaluated for different intensity of base excitation. Shake table tests are performed on cantilever CFRP composite square hollow tube subjected to base excitation with varying amplitudes. The tube is filled with foam balls (of two different sizes) for varying depths of filling (no filling, one-third, two-third, and full). Accelerometers are mounted at different positions along the tube length and at the table to record the accelerations data for evaluation of damping ratio. From the recorded responses, frequency, mode shape and damping ratio of the fundamental mode are evaluated using a well-known approach. The damping ratio is noted to be around 1.41x (times) higher for the completely foam ball (bigger size) filled case under r.m.s base acceleration of 0.3 g when compared with the values corresponding to the empty case. The results suggest that the bigger foam balls enhance the damping ratio significantly without altering the natural frequency owing to additional energy dissipation in friction and impact generated through the sliding and collision of the balls while the tube is in motion.

Kenaikan Tingkat Kebisingan Ruangan Kelas Akibat Pengaruh Penyejuk Udara dan Lalu Lintas

<p>Noise level in the classroom is a factor affecting the learning process. This study aims to determine the level of indoor noise of a private university campus in West Jakarta. Measurements were made using Sound Level Meter that can record the noise level every second with accuracy up to 0.1 dBA. Sampling was carried out in a number of classrooms in an empty condition, closed door, and air conditioning system either in off or on position. Classrooms are distinguished based on the condition of the wall, namely the window facing the outside environment and massive walls without windows to the environment. The measurement results indicate a significant difference in noise level at a 95% confidence level in an empty classroom when the air conditioning system is not functioning and when the system is running. Differences also occur in classrooms with and without windows to the environment. The difference shows that the classroom in an empty condition can experience an increase in latent noise level due to the operation of the air conditioner between 5.78-16.49 dBA. Increased noise from the environment including the highway is about 3 dBA for classrooms located on the 5^th floor, with a horizontal distance about 100 meters from the highway and has thick and permanent glass windows.</p>

A Study on Damping Ratio in the Design Code of Vertical Vessels Supported by Skirt

The vertical vessels supported by skirt are sensitive to dynamic loads, that might oscillate intensely under earthquake and wind loads. Therefore, calculating the dynamic loads and response accurately, especially the damping ratio, influences the amplitude of vessels vibration greatly and is vital for safe operation of the vertical vessels. In Chinese design code, the damping ratio is 0.01 for steel structure, and in American code, it consists of structural damping βs and aerodynamic damping βa, while in European code, the additional damping βd is also considered. With full-scale field tests, the damping ratios of vertical vessels, through a thorough data collection, is recommended as 0.002∼0.005. The damping ratio is 2/3 less than the design value 0.01 in empty condition, that makes the vessel in a crucial state. A new design concept is proposed that the damping ratio of vertical vessels should be determined based on various conditions. Fatigue checking is required in empty condition besides designing by code in operating condition. In addition, the allowable placement time [Tp] is calculated in empty condition. The actual placement time Tp should satisfy Tp < [Tp] and the damper should be installed on the vertical vessel to provide additional damping ratio in the case of Tp > [Tp]. An experiment was carried out to illustrate the new design concept that the damping ratio was enlarged by installing dampers. The damping ratio with other research could provide fundamental parameters for the amendment of the design code.

Integrated Tolerancing and Motion Error Analysis of Suspension Assembly Considering Local Deformation in Suspension Shock Tower

The suspension spring compression introduce local deformation in the suspension shock tower, and it brings the imprecision or uncertainty of the computer aided tolerancing (CAT) results of the suspension assembly. This work presents an integrated tolerancing and motion error analysis method of suspension assembly to consider the local deformation in the suspension shock tower. Tolerancing model of the suspension assembly is constructed in CAT software. FEA model provides the local deformation in the suspension shock tower introduced by the suspension spring compression under full loaded condition. The local deformation is represented with the modified probability distribution function (PDF) of the joining point between the suspension and the suspension shock tower. The modified PDFs of the joining points, together with the manufacturing deviations of the suspension parts are input to the constructed tolerancing model. The results are obtained that the final assembly variations of the suspension assembly under empty and full loaded conditions. Based on the tolerancing results, motion errors of the suspension from empty condition to full loaded condition are analyzed with the ADAMS model of the suspension. The results have shown that tolerancing and motion error analysis results considering the local deformation in suspension shock tower are more accurate than the initial normal distribution. The tolerancing and motion error analysis work presented in the paper will enhance the understanding of the suspension assembling, and help systematically improving the precision control efficiency in automobile industry.

Analisis Tingkat Kebisingan di Kawasan Kampus Universitas Putra Indonesia (UPI) di Kecamatan Lubuk Begalung Kota Padang

The purpose of this research is to analyze the data measuring the noise level in the campus of the University of Putra Indonesia (UPI). Measurement point exterior and interior consists of 12 points and 7 points. The measurement method is based on Decree of the Indonesia Minister of Environment No. 48 of 1996 on Baku Noise is a method simple way by using Sound Level Meter. The highest level of exterior noise when L1 at the point of the Campus Gate UPI (1A) of 73.72 dB (A). The noise level in the afternoon (LS) between 69.63 to 61.60 dB (A), the noise level night (LM) between 48.10 to 38.72 dB (A) and the day-night noise level (LSM) between 67.91 to 59.93 dB (A). The highest current interior noise levels of activity in Building D (2B) of 69.96 dB (A), while the highest level of interior noise occurs at the point when empty Building G (7B) of 69.37 dB (A). Value exterior noise when the time L1-L4 exceeds Raw Noise Level while the value of interior noise when the condition activity partly exceeded Raw Noise except Building G (7B) and the value of noise when empty condition partly exceeds the noise level except Building UPI Sport & Exhibition Hall (1B), Building B (3B) and Building A (4B). Control recommendations exterior form of vegetation while the interior of the control building construction improvements. Keywords: noise, University of Putra Indonesia (UPI) campus, exterior, interior, control alternative recommendationABSTRAKTujuan penelitian adalah menganalisis data pengukuran tingkat kebisingan di kawasan Kampus Universitas Putra Indonesia (UPI). Titik pengukuran eksterior dan interior terdiri atas 12 titik dan 7 titik. Metode pengukuran berdasarkan KepMen LH No. 48 Tahun 1996 tentang Baku Tingkat Kebisingan yaitu metode cara sederhana dengan menggunakan alat Sound Level Meter. Tingkat kebisingan tertinggi eksterior pada saat L1 di titik Pintu Gerbang Kampus UPI (1A) sebesar 73,72 dB(A). Tingkat kebisingan pada siang (LS) antara 69,63-61,60 dB(A), tingkat kebisingan malam (LM) antara 48,10-38,72 dB(A) dan tingkat kebisingan siang-malam (LSM) antara 67,91-59,93 dB(A). Tingkat kebisingan interior tertinggi saat aktivitas di Gedung D (2B) sebesar 69,96 dB(A) sedangkan tingkat kebisingan interior tertinggi saat kosong terjadi di titik Gedung G (7B) sebesar 69,37 dB(A). Nilai kebisingan eksterior saat waktu L1-L4 melebihi Baku Tingkat Kebisingan sedangkan nilai kebisingan interior saat kondisi aktivitas sebagian melebihi Baku Tingkat Kebisingan kecuali Gedung G (7B) dan nilai kebisingan saat kondisi kosong sebagian melebihi baku tingkat kebisingan kecuali Gedung UPI Sport & Exhibition Hall (1B), Gedung B (3B) dan Gedung A (4B). Rekomendasi pengendalian eksterior berupa penanaman vegetasi sedangkan pengendalian interior berupa perbaikan konstruksi bangunan.Kata kunci: kebisingan, kampus Universitas Putra Indonesia (UPI), eksterior, interior, rekomendasi alternatif pengendalian

Analysis and Implementation of Noncontact Level Sensing for a Pressurized Cylinder

Fluid level detection for a sealed and pressurized mobile container is very useful for the provider to schedule the delivery of a new one before it runs out of the liquid. This study suggested using the frequencies of tone generated by knocking on the outside surface of the container to detect the liquid level inside. A detailed model based on Euler-Bernoulli beam theory has been proposed to study the feasibility of this method for a cylinder with complicated but practical structure. Household gas cylinders were used to validate the proposed model and the results show that experimental data agree well with the theoretical analysis. The results indicate that the proposed model can accurately explain the behavior of the vibratory frequencies under different liquid levels. An apparatus has been successfully implemented to automatically sense the near empty condition of the gas cylinder.

Effect of Lay Angle of Anti-Buckling Tape on Lateral Buckling Behavior of Tensile Armors

During deep water flexible pipe installation, the pipe is normally free hanging in empty condition from the installation vessel to the seabed. This will introduce large hydrostatic forces to the pipe causing true wall compression. In addition, the pipe will be exposed to cyclic bending caused by waves and vessel motion. The combination of true wall axial compression and cyclic bending may lead to tensile armor instability in both lateral and radial directions. If the anti-buckling tape is assumed to be strong enough, the inner tensile armor will lose its lateral stability first due to the gap that may occur between the inner tensile armor and the pipe core, hence restricting the available friction restraint forces. These may further be reduced by cyclic motions that act to create slip between the layers, hence introducing lateral buckling of the tensile armor, with associated severe global torsion deformation of the pipe, ultimately causing the pipe to lose its integrity. The anti-buckling tape is designed to prevent the radial buckling behavior, however, its effect on lateral buckling has not yet been documented in available literature. In the present paper, the effect of the winding direction of the anti-buckling tape on the twist of the cross section is studied, including comparisons with available test data from literature.