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This paper deals with the scaling factor's effect on the cantilever beam's natural frequency. Scaling a prototype dimension will make it easier to manufacture and test the dynamic characteristics of structures with enormous sizes. Natural frequency is one of the essential parameters of the vibration characteristics of the system. The phenomenon that often occurs in vibrating structures is the resonance phenomenon. Resonance is a system state in which an abnormally large vibration is generated in response to an external stimulus, happening when the frequency of the disturbance is equal to, or nearly identical to, the natural frequency of the system. This research investigates the scale factor on natural frequency using the analytical method using Euler-Bernoulli beam theory, the MSC Nastran/Patran software, and experimental testing using an impact hammer on a cantilever beam. The three methods were applied to beams with four scaling variations: 1:1, 1:2.04, 1:2.85, and 1:3.48. Based on the results, the natural frequencies increase by the size scale reduction value in the modeling. The natural frequency value in the actual structure has a value equivalent to 1/S of the natural frequency value of the scale, whereas S is defined as the downgrade scale value. This result follows the Similitude theory.

This study offers a mechanism to control low-speed orientation using semi-active control. The semi-active system consists of a variable mass system and a torsional spring. The torque generated by a variable mass system controls the platform’s orientation. An evaluation of the control system’s effectiveness is tested on a solar panel. The variable mass was represented by moving the water from one reservoir to another located at the left and right sides of the panel using an electrical pump. A solenoid valve controls the flow. The test results indicate that the energy consumption of electrical pump as actuators is reduced. Based on several references, the actuator energy consumption for controlling the orientation of solar panels was generally 2% - 3%, while in this study 0.79%. .

A landing gear model using a four-bar linkage mechanism is proposed in this study. The simulation study was conducted to evaluate the effect of the link dimension variation and coil spring constant on the equivalent stiffness and static deflection of the landing gear. The simulation results show that increasing the landing gear dimension affects the static deflection of the landing gear. However, the linear stiffness of the landing gear system is not much affected by the landing gear dimension variation. Furthermore, the landing gear stiffness characteristic is nonlinear for large landing gear displacement.

This research presents a response analysis of a UAV nose landing gear system equipped with an air damper under shock and harmonic excitation. The study begins with dynamic modeling of the UAV landing gear system. The system dynamics consists of a main mass and a wheel mass that are connected to each other by a U-shaped landing gear. The U-shaped landing gear is modeled by a linear spring and dashpot element. The air damper is added to the landing gear to increase the damping. The air damper consists of an air balloon that is connected to the outside via an orifice hole and the connecting pipe. A serial connection of spring, mass, and dashpot elements describes the air damper dynamic model. The simulation study is conducted to evaluate the effect of the landing gear parameters variation on the UAV dynamic response under shock and harmonic excitation. The maximum acceleration and displacement response of the UAV body under shock load is greatly affected by the air balloon cross-sectional area (Aef) and the stiffness of the U-shaped landing gear system (KL). The harmonic response of the UAV body is evaluated from the ratio between the UAV body displacement amplitude and the base excitation amplitude under harmonic excitation. It is shown that the air balloon cross-sectional area (Aef) and the connecting pipe length (lp) have a significant effect on the UAV mass displacement ratio. The experimental study is conducted to validate the simulation results. It is shown that the experimental data can verify the simulation results.

Pada paper ini dikaji optimasi postur mekanisme paralel 3-URU rotasi murni. Optimasi inidigunakan untuk memperoleh kekakuan kinematik yang optimal berupa kemampuanmekanisme meneruskan torsi input dan kemampuan mekanisme menahan gaya luar yangdinyatakan dengan indeks evaluasi (EI). Optimasi meliputi pemilihan parameter kinematikyang menggambarkan gerak platformyang dinyatakan dengan rotasi berurut berdasarkanEuler Angle dengan sistem rotasi Z-X-Z. Euler Angle tersebut dinyatakan dengan , , z x ? ? ? .Pada penelitian ini mekanisme paralel rotasi murni 3-URU diaplikasikan sebagaipengontrolan orientasi pahat pada mesin perkakas. Pada aplikasi ini sudut ? merupakansudut redundant yang menyatakan putaran pada sumbu yang tegak lurus terhadap bidangplatform. Berdasarkan hasil analisis diperoleh bahwa ? optimal merupakan fungsi sudutinklinasi platform ?()x yang dapat diformulasikan dengan6 5 4 3 2 1 -08( ) 4 -06( ) 0.0008( ) 0.0151( ) 0.3143( ? optimal ? ? E ?x ? E ?x ? ?x ? ?x ? ?x ) 3.9654( ) 79.977 x ? ? ? .Denganmenggunakan formulasi sudut redundant ini telah didapatkan kekakuan yang optimal yangdinyatakan dengan indek evaluasi EI.Kata kunci: kinematik, mekanisme paralel, constraint singularity, actuation singularity In this paper was studied the optimization of posture of a 3-URU spherical parallelmechanism. The mechanism was applied tocontrol the orentation of platform represented bythree successive Euler Rotation Angles. The rotation angle was denoted as ? , ? , ? z x thatindicates the rotation about Z, X dan Z axis respectively. Based on the desired aplication, thethird rotation angle, ? was recognized as redundant degree dof because such rotation is notrequired as orienting tool. The optimization was carried out to realize optimal kinematicstiffness of the mechanism to transmit the torques and to restrict the external forces acting onthe center of platform motion indicated by evaluation index, EI. Based onthis works, it wasobtained that the optimal ? is a function ofthe angle of inclinationplatform,? x formulated as6 5 4 3 2 1 -08( ) 4 -06( ) 0.0008( ) 0.0151( ) 0.3143( ) 3.9654( ) 79.977 optimal x x x x x x ? ? ? E ? ? E ? ? ? ? ? ? ? ? ? ? . The optimizegave the highes of EI.Keywords: kinematic, parallel mechanism, constraintsingularity, actuationsingularity

The web-based PV system monitoring to measure electrical production and consumption to the load or utility grid is presented in this paper. This monitoring system consists of an Arduino Mega 2560 with two PZEM 004T sensor modules. The monitoring system has been designed to store measurement data of current, voltage, power and energy in the database and display on the webpage in real time and infographics history. The PZEM sensor measurement has been tested with an average power difference 0.29% less than IEC-61724 minimum-accuracy. Realtime data is obtained in the form of one-line data for every 2 seconds, with a data size of 375-byte and 75ms delivery delay. For one day period testing, the electrical energy that can be generated by the PV system is 5,925 kWh, while the power consumed by the load is only 1,272 kWh so the accumulated electrical energy that can be exported is 4.65 kWh. The test results show that the system has been able to measure net energy export or import by the PV system to utility grid. [ABSTRACT FROM AUTHOR]