The effect of printing parameters (nozzle diameter, layer height, nozzle temperature, and printing speed), dimensions (wall thickness), and filament material on the crashworthiness performance of 3D-printed thin-walled multi-cell structures (TWMCS) undergoing quasi-static compression is presented. The ideal combination of parameters was determined by employing the Signal-to-Noise ratio (S/N), while Analysis of Variance (ANOVA) was utilized to identify the significant parameters and assess their impact on crashworthiness performance. The findings indicated that the ideal parameters for the specific energy absorption (SEA) consisted of a nozzle diameter of 0.6 mm, layer height of 0.3 mm, nozzle temperature of 220 °C, printing speed of 90 mm/s, wall thickness of 1.6 mm, and PLA(+) filament material. Afterward, the optimal parameters for crushing force efficiency (CFE) included a nozzle diameter of 0.8 mm, layer height of 0.3 mm, nozzle temperature of 230 °C, print speed of 90 mm/s, wall thickness of 1.6 mm, and PLA(ST) filament material. The optimum parameter to minimize manufacturing time is 0.3 mm for layer height and 90 mm/s for printing speed. This research presents novel opportunities for optimizing lightweight structures with enhanced energy absorption capacities. These advancements hold the potential to elevate passenger safety and fortify transportation systems. By elucidating the fundamental factors governing the crashworthiness of thin-walled multi-cell PLA 3D-printed tubes, this study contributes to a deeper understanding of the field.

A novel S‐band right handed circularly polarised (RHCP) slot antenna for supporting communication system of GAIA II/LAPAN‐Chibasat is presented in this paper. This satellite implemented L‐band Circularly Polarised Synthetic Aperture Radar (CP‐SAR) sensor, X‐band antenna is employed for mission data downlink and S‐band antenna is employed for the command and telemetry. The S‐band antenna is printed on the substrate with the relative permittivity of 2.17 and the thickness is 1.6 mm. A crescent shaped slot is placed on the ground plane. A square‐shaped is set to strengthen the radiation on the edge of the feed‐line. A parasitic strip rectangular‐shaped is added on the ground plane to enhance the gain of the antenna. Truncation technique is employed to increase the bandwidth axial ratio(ARBW) and the gain. The total dimension of the antenna is 170 mm × 170 mm. The antenna produced <3 dB bandwidth axial ratio of 14% and the bandwidth under −10 dB of return loss obtained 90%.The simulated and measured result of the antenna design is satisfied. Detail of the antenna design and the measurement result of the antenna are described and presented.

The development of linearly polarized slotted patch antenna array fed by power weighting distribution is presented. The antenna array which consists of 5 slotted square patches is designed to work at X-band frequency for radar application. A Chebyshev power weighting distribution is implemented for the antenna array to suppress the side lobe level of antenna. Meanwhile, by inserting a slot over each patch which is perpendicular to its feeding line, the linear vertical polarization can be changed into the perpendicular one. It shows that the proposed antenna array has linear polarization with side lobe level (SLL) around 19.8dB at frequency of 9.3GHz. This is 6.8dB lower than the SLL of antenna array fed by uniformly power distribution.

Synthetic Aperture Radar (SAR) is a very powerful tool in microwave remote sensing due to its capability of all-weather and day-to-night time operation [1]. Carl Wiley invented SAR in 1951 to overcome the poor azimuth resolution in conventional Side-Looking Airborne Radar (SLAR), followed by a patent filed in 1954 [2]. Unlike SLAR, using the forward motion of the platform and the principle of Doppler beam sharpening, the azimuth resolution of a SAR is equal to half the antenna length and is independent of the range distance [3]. Since the invention of SAR, steered by the breakthrough in science and technology, many advanced SAR techniques have been proposed and realized. These techniques include, but are not limited to, spotlight SAR for a finer image resolution [4], scan SAR for a wider swath coverage [5], and the remarkable polarimetric [6] and interferometric [7] SAR techniques using multichannel SAR system [8], [9], [10] for advanced remote sensing applications. Over the years, SAR has been widely used in different types of application, particularly in Earth observation such as disaster damage assessment [11], land deformation observation [12], oceanography [13], terrain classification [14], target detection [15], and so on. The diversified applications of SAR have encouraged the rapid development of airborne and spaceborne SAR sensors.