Journal of Engineering and Technological Sciences
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The Evolution of Seismic Design Provisions in Indonesia's National Bridge Code
Full text linkTo accommodate increased seismic hazards in Indonesia, provisions regarding structural details on seismic regulations have been tightened. In this paper, the variations in seismic hazard and detailing requirements from bridge code era before 1990 to the present was provided. To examine the bridge performance, pushover analysis was carried out based on the latest bridge code SNI 2833:2016/Seismic Map 2017. From the analysis results, the performance of older bridges would typically be less than more recently designed structures. The performance level of the bridge in the era before SNI 2833:2016/Seismic Map 2017 will be Operational-Life Safety (LS) whereas the performance level of the bridge designed with SNI 2833:2016 will be Elastic – Operational. Referring to NCHRP 949 for bridge performance level evaluation, results show that the performance level of the bridge still satisfies the requirement, which is Life Safety under upper-level earthquake. Therefore, the existing bridge shows adequate capacity under the current seismic load Seismic Map 2017 (7% probability of exceedance in 75 years (RP= 1000 years)). Evaluation of seismic vulnerability needs to be done to ensure the safety of the existing bridges in Indonesia, most of which are located in earthquake-prone areas, especially those that were designed with older version regulations
An Enhanced Dynamic Spectrum Allocation Method on Throughput Maximization in Urban 5G FBMC Heterogeneous Network
Full text linkReports have shown that the demand for data managed by wireless systems is expected to grow by more than 500 exabytes by 2025 and beyond. 5G networks are predicted to meet these demands, provided that the spectrum resources are well managed. In this paper, an enhanced dynamic spectrum allocation (E-DSA) method is proposed, which incorporates a cooperative type of game theory called the Nash bargaining solution (NBS). It was assumed that there is one primary user (PU) and two secondary users (SU) in the network and their spectrum allocation was analyzed by testing the validity of the algorithm itself by using price weight factors to control the costs of the spectrum sharing. The solution was established by combining a proposed multiplexing method called the Filter Bank Multicarrier (FBMC) for 5G configuration, with the E-DSA algorithm to maximize the throughput of a heterogeneous 5G network. It was shown that the throughputs for 5G with E-DSA implementation were always higher than those of the ones without E-DSA. The simulation was done using the LabVIEW communication software and was analyzed based on a 5G urban macro and micro network configuration to validate the heterogeneity of the network
Design of a Novel Efficient High-Gain Ultra-Wide-Band Slotted H-Shaped Printed 2×1 Array Antenna for Millimeter-Wave Applications with Improvement of Bandwidth and Gain via the Feed Line and Elliptical Edges
Full text linkThis paper describes design procedure of a high-performance miniaturized antenna with an array configuration, which contributes to enhancing the communication system’s performance. The basic antenna features a compact size (6 x 6) mm2, and its single element is an H-shaped slotted patch printed on the top side of a Rogers RT5880 substrate, with a relative permittivity and thickness of 2.2 and 0.3 mm, respectively. The edge-to-edge distance of the 2 × 1 array antenna is 9 x 14 mm2, and the isolation between its radiation elements is 4.5 mm. To increase the capabilities of the antenna in terms of gain and bandwidth, we proceeded to use the 2 × 1 array configuration and then optimized the model via either the width of the feed line or the elliptical edges of the patch. The miniaturized array antenna achieved a peak gain of 12.56 dB, a directivity of 13.11 dBi, and a return loss of -47.52 dB at a resonance frequency of 91.5 GHz, with a radiation efficiency of more than 91% over an operating bandwidth of 15.83 GHz, ranging from 79.7 GHz to 95.6 GHz. The design and simulation results of the proposed antenna were obtained using the CST Studio software
Laboratory Investigation of Micronized Lomashell Powder Effects on Asphalt Binder and Mix Performance
Full text linkLomashell, a mineral stone derived from oyster shells and skeletons, is widely available in Iran and across the globe. Typically used for livestock feed due to its high calcium content, its production generates a considerable amount of discarded fine grains. This research focused on incorporating micronized Lomashell as additive for asphalt pavement to enhance performance and environmental sustainability. The impact of this powder on the rheological and physical properties of two common asphalt binders was evaluated. Moisture resistance, rutting, and permanent deformation of Lomashell-enhanced asphalt mixtures were also examined. The results indicate significant improvements in rheological properties and dynamic shear rheometer parameters upon Lomashell addition. Moisture sensitivity was enhanced, as demonstrated by the indirect tensile strength test. Adding 7% of this material to the asphalt mixture enhanced indirect tensile strength by 12% compared to control. Furthermore, utilizing the Hamburg wheel-tracking device (HWTD), it was observed that inclusion of this powder enhanced resistance against permanent deformation, as evidenced by the rutting resistance index (RRD) values. Effective high-speed shear mixing is emphasized for binder modification, as revealed by scanning electron microscopy analysis. These findings highlight Lomashell’s positive influence on the overall performance and durability of the asphalt mixtures, reducing rutting and enhancing resistance against permanent deformation. Utilizing this powder as asphalt additive holds promise for improving functionality and addressing environmental concerns, contributing to sustainable infrastructure development
