Analysis and optimisation design on damping orifice of oleo-pneumatic landing gear

This paper investigates the feasibility of improving the aircraft landing performance by design the damping orifice parameters of the landing gear using lattice Boltzmann method coupled with the response surface method. The LBM is utilised to simulate characteristics of the damping orifice after model validation. The numerical model of the landing gear using simulated damping force is validated by single landing gear drop test. Based on the numerical model and the response surface functions, the sensitivity analysis and the optimisation design are performed. The maximum error of mean velocity simulated using LBM with experimental data is 7.07% for sharp-edged orifices. Moreover, the numerical model predicts the landing responses adequately, the maximum error with drop test data is 2.51%. The max overloading of the aircraft decreases by 5.44% after optimisation, which proves that this method is feasible to design the damping orifice for good landing performance.

Ageing of climbing ropes with and without hydrophobic coating

The effects of 4 months of weather exposure on the ageing of dynamic climbing ropes made of polyamide 6 were studied and differences between ropes with and without hydrophobic coating were examined. The polyamide degradation of the rope yarns was studied using infrared spectroscopy and a quasi-static tensile test. The number of falls to failure and the maximum force on the climber in a fall were evaluated with a drop test according to the UIAA 101 standard. Moreover, changes in the length of the ropes due to weathering were measured. The following results were found. After 4 months of weathering, sheath yarns of the coated rope showed a greater decrease in breaking force than those of the uncoated rope, which might be due to reactions of polyamide with radicals formed during the photo-induced oxidation of the coating. In contrast, the core yarns from the uncoated rope showed a greater decrease in breaking force than those from the coated rope, probably due to prolonged exposure of the uncoated core to water with possibly dissolved atmospheric acids. Furthermore, the decrease in the number of falls to failure was greater in the uncoated than in the coated rope. This difference was explained by a mechanism of changes in radial pressure of the sheath on the core. Regarding the maximum force on the climber, no significant changes due to ageing were observed during the drop test. Thus, it was concluded that 4 months of weather exposure do not pose a safety risk for climbing ropes, but the negative effect of coating on the ageing of polyamide might be detrimental when it comes to static personal safety equipment, such as slings or accessory cords.

Simulation Study of a Composite Landig Gear of Ultralight and Very Light Aircraft

There is a need to design new, lighter aircraft structures, which has a direct impact on the safety and costs of aircraft maintenance. One of basic parts of an aircraft is ites landing gear, whose main functions are to enable taxiing, safe landing, take-off, and to assist the remainder of ground operations. Landing gear failures are usually related to metallurgy, processing, environment, design, and causes of overload. These are conditions that can be prevented using modern methods to calculate the strength of such a landing gear in various conditions. The paper presents stages of a simulation study of the fixed three-wheeled spring landing gear for an ultralight aircraft. Analysis of forces acting on the landing gear during drop test and their implementation by numerical computer methods allowed for the creation of a model in the CAD (Computer-Aided Design) tool and its FEA (Finite Element Analysis). These results were compared between a modeled classic spring landing gear and the one made of composite materials. The further goal of the research will be to build a drop test stand for a small landing gear used in airplanes and drones. This method has a significant impact on simplifying the design of the landing gear, its modeling, and optimization.

APLIKASI BIOBRIKET SEBAGAI AROMATERAPI UNTUK MEMBERANTAS NYAMUK

Penyakit Demam Berdarah Dengue (DBD) merupakan salah satu penyakit yang mewabah serta berbahaya karena setiap tahun jumlah penderita semakin meningkat. Vektor dari penyakit ini adalah nyamuk Aedes spp. Banyak metode telah digunakan untuk memutus atau mengurangi populasi nyamuk Aedes spp. Metode tersebut antara lain adalah insektisida sintetik, tanaman penghalau nyamuk maupun sistem fogging. Penggunaan insektisida sintetik. Namun demikian, penggunaan metode tersebut cukup berbahaya karena mengandung senyawa kimia yang mampu membahayakan kesehatan manusia. Senyawa yang ada pada tanaman serai maupun cengkeh mampu menghambat perkembangan serangga dan sifatnya toksik, tannin berfungsi menghalangi serangga dalam mencerna makanan. Sisi aromaterapi dapat diperoleh dari tanaman tersebut yang memiliki khasiat bagi kesehatan. Kombinasi manfaat pengusir nyamuk serta aromaterapi apda briket organik atau biobriket dapat menjadi inovasi terbaru guna meningkatkan nilai tambah dari briket arang. Produk yang dibuat pada penelitian ini diberikan nama BRIO. Berdasarkan uji hedonisme menunjukkan bahwa BRIO mampu mengusir nyamuk sebesar 90% dengan aromaterapi 80%. Uji fisik dan kimia dari BRIO memperlihatkan bahwa kerapatannya 0,554 dan 0,64 g/cm2 , drop test 60-70% serta kadar air 19,78% dan 22,79% kemudain nilai kalor 4799 kal/g dan 4894 kal/g. Beberapa uji masih dibawah standa mutu briket menurut BSN

Study on the Influence of Proprioceptive Control Versus Visual Control on Reaction Speed, Hand Coordination, and Lower Limb Balance in Young Students 14–15 Years Old

Currently, sports activities require a high reaction speed, coordination, and balance, highlighting the relationship between proprioceptive control, visual control, and hand–eye coordination in youth. The present research assessed the proprioceptive control, reaction speed, and lower limb balance of youth from five different schools to identify the level of physical preparation of children in this direction. This prospective study was conducted between 1 January, 2020, and 29 February, 2020. A total of 107 healthy children (33 females and 74 males) with appropriate medical conditions, aged between 14 and 15 years, from five Romanian schools were included in the experiment. All children were assessed for visual control and reaction speed with the ruler drop test, and for lower limb balance, the standing stork test was used. Statistical analysis included descriptive statistics, data series distribution, and comparison of means and medians using specific statistical programs. Comparison of medians highlighted significant statistical differences in the standing stork test with eyes closed and the dominant leg compared with the nondominant leg (p = 0.0057). Males were compared to females at the nondominant leg (p = 0.0179); closed eyes were compared with opened eyes for the nondominant leg (p = 0.0175 and 0.0006) for the ruler drop test comparing the dominant hand with the nondominant hand (p = 0.0212). Children who engage in sports activities better integrated sensory information in motor action execution based on reaction speed and coordination with the nondominant hand.

The effect of drill exercise and reaction speed on the drive accuracy of beginner table tennis athletes

This study aimed to test (1) the differences of drill practice effect of a constant set of rising repetition and rising set of repetition continually on drive accuracy (forehand and backhand drive) for the beginner table tennis athletes, (2) the differences of the effect of high and low reaction speed on the drive accuracy (forehand and backhand drive) for the beginner table tennis athletes in Yogyakarta, and (3) the relation between drill practice and reaction speed on improving the drive accuracy (forehand and backhand drive) for the beginner table tennis athletes in Yogyakarta. This research used an experiment with a 2 x 2 factorial design. The sample was 20 beginner table tennis athletes in Yogyakarta, taken with random technique from a population of 38 athletes. The instrument for measuring reaction speed was the ruler drop test and for measuring the forehand and backhand drives was the precision of the drive accuracy. The data were analyzed using two-way ANOVA at significance level α = 0.05. The results of the study were as follows. (1) There were significant differences in the effect of a constant set of rising repetition and rising set of repetitions continually to drive accuracy (forehand and backhand drive) for the beginner table tennis athletes, as proven by the value of F = 7.538 and p = 0.014 <0, 05. The drill practice of a constant set of rising repetition was higher than the drill practice of a rising group of repetition always. (2) There was a significant difference effect of high and low reaction speeds to drive accuracy (forehand and backhand drive) for the beginner table tennis athletes, as proven by the value of F = 21.442 and p = 0.000 <0.05. High reaction speed was better than low reaction speed. (3) There was a significant relation between drill practice and reaction speed on improving punch drive accuracy (forehand and backhand drive) for beginner table tennis athletes, as proven by the value of F = 136.398 and p = 0.000 <0.05.