PMMA Application in Piezo Actuation Jet for Dissipating Heat of Electronic Devices

The present study utilizes an acrylic (PMMA) plate with circular piezoelectric ceramics (PC) as an actuator to design and investigate five different types of piezo actuation jets (PAJs) with operating conditions. The results show that the heat transfer coefficient of a device of PAJ is 200% greater than that of a traditional rotary fan when PAJ is placed at the proper distance of 10 to 20 mm from the heat source, avoiding the suck back of surrounding fluids. The cooling effect of these five PAJs was calculated by employing the thermal analysis method and the convection thermal resistance of the optimal PAJ can be reduced by about 36%, while the voltage frequency, wind speed, and noise were all positively correlated. When the supplied piezoelectric frequency is 300 Hz, the decibel level of the noise is similar to that of a commercial rotary fan. The piezoelectric sheets had one of two diameters of 31 mm or 41 mm depending on the size of the tested PAJs. The power consumption of a single PAJ was less than 10% of that of a rotary fan. Among the five types of PAJ, the optimal one has the characteristics that the diameter of the piezoelectric sheet is 41 mm, the piezoelectric spacing is 2 mm, and the length of the opening is 4 mm. Furthermore, the optimal operating conditions are a voltage frequency of 300 Hz and a placement distance of 20 mm in the present study.

Demersal Fish Diversity Index in Cirebon Waters, West Java

This study aims to analyze the distance between the placement of the base fish aggregating devices (FAD) from the beach, the composition of the catch, identify fish species and determine the diversity of fish caught at different distances of the base FAD in Cirebon waters. The research method was carried out descriptively by census. Data analysis method for demersal fish diversity index value (H') using Shannon-Wiener and t-test. Sampling of respondents was carried out by census as many as 20 basic FAD fishermen. The research location is in the Cangkol Tengah Fishermen Association, Cirebon City. The results of this study indicate that the number of fish species caught on FADs with a distance of <12 miles was obtained 10 species with 6,784 fish, the largest number of fish caught was snapper (Lutjanus Campechanus) as many as 2,040 fish with a percentage of 30.2% of the total number of fish. The whole fish caught, while the fish with the largest weight was snapper for distances <12 miles with an average weight of 658.92 kg or 30% of other types of fish. The number of fish species caught on FADs with a distance of >12 miles obtained 10 species with 9.217 fish, the highest number of fish caught was snapper (Lutjanus Campechanus) as many as 2,884 fish with a percentage of 27.97% of the total number of fish caught, while the fish with the greatest weight is snapper with an average weight for distances >12 miles of 988.39 kg or 30% of other types of fish. The magnitude of the demersal fish diversity index value at the base FAD placement distance <12 miles was 1.6672 and more than 12 miles was 1.8137 which means that there is no significant difference and the diversity index category is small because the value of H '≤ 2.

PENGARUH PENEMPATAN JARAK TITIK LAMPU DAN KOMBINASI WARNA TERHADAP PERUBAHAN KONDISI LINGKUNGAN LAPANGAN INDOOR BULUTANGKIS

This research aims to measure whether there is effect of placement of the point of lights and color combinations to changes in the environmental conditions of indoor badminton court. The design of the research was experimented research. The color of light used was white, yellow and combination of both. Modified layout and placement distance is done with a combination of parallel and zig-zag, and 7, 7.5, 8, 8.5, and 9 m lamp height. Measurements using Thermometer, Hygrometer, and Luxmeter. The research was also conducted by field survey using questionnaire method to 5 athletes. The results of data collection will be analyzed based on the SNI 16-7063-2004 working climate criteria as well as the criteria for grouping existing data. The results showed that the placement of the point of light and color combinations affect the environmental conditions of indoor badminton field. The athlete's comfort lies in the placement of standard lighting points with one color at a height of 8 meters.ABSTRAKPenelitian ini bertujuan untuk mendapatkan pengaruh penempatan jarak titik lampu dan kombinasi warna terhadap perubahan kondisi lingkungan lapangan indoor bulutangkis. Penelitian dilakukan dengan eksperimen, enis warna cahaya lampu yang digunakan adalah putih, kuning dan kombinasi keduanya. Modifikasi tata letak dan jarak penempatan dilakukan dengan kombinasi sejajar dan zig-zag, dan ketinggian lampu 7, 7.5, 8, 8.5, dan 9 m. Pengukuran menggunakan Thermometer, Hygrometer, dan Luxmeter. Penelitian juga dilakukan dengan cara survei lapangan menggunakan metode kuesioner terhadap 5 atlet. Hasil pengambilan data akan dianalisis berdasarkan nilai ambang batas iklim kerja SNI 16-7063-2004 serta kriteria pengelompokkan data yang ada. Hasil penelitian menunjukan bahwa penempatan jarak titik lampu dan kombinasi warna berpengaruh terhadap kondisi lingkungan lapangan indoor bulutangkis. Kenyamanan atlet terletak pada penempatan titik lampu standart dengan satu warna pada ketinggian lampu 8 meter.

Proper Design of Leachate Collection Pipe in Semi-Aerobic Landfill by Two Dimensional Simulation

Semi-aerobic method is a standard type of landfill currently used in Japan. Semi-aerobic landfill system enables to enhance the stabilization of landfilled solid waste utilizing the self-purification capacity inherent in nature. Although semi-aerobic method has been developed for about 20 years, the mechanism has not widely understood in many countries. The objective of this study is to make clear the influence of the laying condition (pipe diameter, pipe placement distance) of leachate collection pipe on the stabilization of landfill through numerical simulation, by use of landfill model constructed in this study with consideration of the interactions of microbial activity and the transport process such as gas transport, heat transport and material transfer between gas and liquid phases.

Prism adaptation and generalization during visually guided locomotor tasks

The ability of individuals to adapt locomotion to constraints associated with the complex environments normally encountered in everyday life is paramount for survival. Here, we tested the ability of 24 healthy young adults to adapt to a rightward prism shift (∼11.3°) while either walking and stepping to targets (i.e., precision stepping task) or stepping over an obstacle (i.e., obstacle avoidance task). We subsequently tested for generalization to the other locomotor task. In the precision stepping task, we determined the lateral end-point error of foot placement from the targets. In the obstacle avoidance task, we determined toe clearance and lateral foot placement distance from the obstacle before and after stepping over the obstacle. We found large, rightward deviations in foot placement on initial exposure to prisms in both tasks. The majority of measures demonstrated adaptation over repeated trials, and adaptation rates were dependent mainly on the task. On removal of the prisms, we observed negative aftereffects for measures of both tasks. Additionally, we found a unilateral symmetric generalization pattern in that the left, but not the right, lower limb indicated generalization across the 2 locomotor tasks. These results indicate that the nervous system is capable of rapidly adapting to a visuomotor mismatch during visually demanding locomotor tasks and that the prism-induced adaptation can, at least partially, generalize across these tasks. The results also support the notion that the nervous system utilizes an internal model for the control of visually guided locomotion.

Thermal investigations of microelectronic chip with non‐uniform power distribution: temperature prediction and thermal placement design optimization

This paper presents the thermal analyses carried out to predict the temperature distribution of the silicon chip with non‐uniform power dissipation patterns and to determine the optimal locations of power generating sources in silicon chip design layout that leads to the desired junction temperature, Tj. Key thermal parameters investigated are the heat source placement distance, level of heat dissipation, and magnitude of convection heat transfer coefficient. Finite element method (FEM) is used to investigate the effect of the key parameters. From the FEM results, a multiple linear regression model employing the least‐square method is developed that relates all three parameters into a single correlation which would predict the maximum junction temperature, Tj,max.