Directional solidification of Pb-Sn eutectic with vibration

Pb-Sn eutectic alloy was directionally solidified at 1.4 to 3.2 cm/hr with forced convection induced by axial vibration of the growth ampoule with a frequency of 10 to 40 Hz and an amplitude of 0.5 to 1.0 mm. To determine the exact growth rate, an interface demarcation technique was applied. The lamellar spacing was increased 10 to 40 percent in ingots solidified with vibration compared to those solidified without vibration. The average intensity of convection in the melt under axial vibration of the ampoule was estimated by comparing the experimental results with a theoretical model

PERBEDAAN MINAT SISWA SMK NEGERI 13 DAN SMK FARMASI BUMI SILIWANGI KOTA BANDUNG DALAM MATA PELAJARAN PENDIDIKAN JASMANI OLAHRAGA DAN KESEHATAN

Tujuan penelitian ini untuk mengetahui apakah ada perbedaan minat siswa antara SMK Negeri 13 Bandung dan SMK Farmasi Bumi Siliwangi Bandung dalam mata pelajaran pendidikan jasmani olahraga dan kesehatan. Dalam penelitian ini penulis menggunakan desain penelitian deskriptif yang dimaksudkan untuk memberikan gambaran mengenai perbedaan variabel-variabel penelitian yang dimaksud. Populasi dalam penelitian ini adalah Siswa SMK Negeri 13 dan siswa SMK Farmasi Bumi Siliwangi. Hasil dari penelitian ini menggunakan perhitungan pengujian hipotesis uji t dan hasil yang diperoleh terdapat perbedaan signifikan antara minat siswa SMK Negeri 13 dan SMK Farmasi Bumi Siliwangi kota Bandung dalam mata pelajaran Pendidikan Jasmani Olahraga dan Kesehatan. Sedangkan untuk nilai perbedaan terlihat dari rata-rata hasil angket SMK Farmasi Bumi Siliwangi sedikit lebih tinggi yaitu 4,221546 dibanding SMK Negeri 13 yaitu 4,090443.---------- The purpose of this research is to know something different about student interest between SMK Negeri 13 Bandung and SMK Farmasi Bumi Siliwangi Bandung on physical education, sport and health. In this research the writer uses descriptive research design to giving description about a different research variables. The population on this research is students of the SMK Negeri 13 and SMK Farmasi Bumi Siliwangi. The result of this research is using hypothesis counting test (t test) and the obtainable results have a significant different between student interest of SMK Negeri 13 and SMK Farmasi Bumi Siliwangi on physical education, sport and health. Whereas a value different can be see from average result quesioner SMK Farmasi Bumi Siliwangi is a bit higher, it’s about 4,221546 then SMK Negeri 13 who get score about 4,090443

An experimental approach to determine the heat transfer coefficient in directional solidification furnaces

The heat transfer coefficient between a molten charge and its surroundings in a Bridgman furnace was experimentally determined using in-situ temperature measurement. The ampoule containing an isothermal melt was suddenly moved from a higher temperature zone to a lower temperature zone. The temperature-time history was used in a lumped-capacity cooling model to evaluate the heat transfer coefficient between the charge and the furnace. The experimentally determined heat transfer coefficient was of the same order of magnitude as the theoretical value estimated by standard heat transfer calculations

A novel approach to determine the heat transfer coefficient in directional solidification furnaces

The heat transfer coefficient between a molten charge and its surroundings in a Bridgman furnace was determined using an approach utilizing in-situ temperature measurement. The ampoule containing an isothermal melt was suddenly moved from a higher temperature zone to a lower temperature zone. The temperature-time history was used in a lumped-capacity cooling model to evaluate the heat transfer coefficient between the charge and the furnace. The experimentally determined heat transfer coefficient was of the same order of magnitude as the value estimated by standard heat transfer calculations

Directional solidification of Pb-Sn eutectics with vibration

Pb-Sn eutectic alloy was directionally solidified at 1.4 to 3.2 cm/hr with forced convection induced by axial vibration of the growth ampoule with a frequency of 10 to 40 Hz and an amplitude of 0.5 to 1.0 mm. To determine the exact growth rate, an interface demarcation technique was applied. The lamellar spacing was increased 10 to 40 percent in ingots solidified with vibration compared to those solidified without vibration. The number of grain boundaries was increased by vibration. The average intensity of convection in the melt under axial vibration of the ampoule was estimated by comparing the experimental results with a theoretical model

Influence of convection on microstructure

The influence was studied of convection during directional solidification on the resulting microstructure of eutectics, specifically lead/tin and manganese/bismuth. A theory was developed for the influence of convection on the microstructure of lamellar and fibrous eutectics, through the effect of convection on the concentration field in the melt in front of the growing eutectic. While the theory agrees with the experimental spin-up spin-down results, it predicts that the weak convection expected due to buoyancy will not produce a measurable change in eutectic microstructure. Thus, this theory does not explain the two fold decrease in MnBi fiber size and spacing observed when MnBi-Bi is solidified in space or on Earth with a magnetic field applied. Attention was turned to the morphology of the MnBi-Bi interface and to the generation of freezing rate fluctuations by convection. Decanting the melt during solidification of MnBi-Bi eutectic showed that the MnBi phase projects into the melt ahead of the Bi matrix. Temperature measurements in a Bi melt in the vertical Bridgman-Stockbarger configuration showed temperature variations of up to 25 C. Conclusions are drawn and discussed

The role of the vocal stream in telepresence communication

This paper helps in developing a new telepresence TP that will capture the vocal stream, and allow users to relate to natural behaviours that spontaneously arise during speech. Most of the work in affective computing within telepresence robot platforms adds to current research and knowledge generation as opposed to application. Consequently, users do not get clear benefits from them in the real world. The main reason behind this lack of benefit is that most research does not represent reality, and the actual capabilities we have in the real world do not match the capabilities that are used in research. Therefore, contemporary telepresence robot design should be based on an understanding of different aspects of human-human interaction (HHI) in regard to that which can be feasibly implemented in TP. Thus, this study will provided step by step guidelines to govern the creation of practical natural user interfaces using the vocal stream

Blastocystis Hominis: is IT a Cause of Diarrhea?

Blastocystis hominis can be found in the fecal sample of both healthy individuals without symptoms and those having gastrointestinal problems. Therefore, the pathogenicity and pathophysiology remain controversial. The aim of this study was to determine if Blastocystis hominis is a causative agent of diarrhea and investigates its prevalence among patients visiting King Abdulaziz University Hospital, Jeddah, Saudi Arabia from January 2013 till June 2015 and to determine any significant correlation between age, gender, nationality and other parasitic infection in the presence of Blastocystis hominis. Data were collected from Parasitology lab, using the database at King Abdulaziz University Hospital, Jeddah, Saudi Arabia and statistical analysis were done by utilizing Statistical package for social science program (SPSS). Out of 3,035 of total stool analysis requested, 157 samples were positive for B. hominis (5.2%). 80 (51.6%) were males, and 76 (48.4%) were females. The distribution of B. hominis infection was elevated in 31-50 aged groups (25.5%). There was a statistically significant correlation between the presence of Blastocystis and diarrhea at p < 0.05 and there was no correlation between age, sex, nationality and other parasites with positivity of B. hominis. Blastocystis can be considered as a causative agent of diarrhea. Further studies need to be done in order to investigate its role in pathogenicity and more data must be revised to assess the pathogenicity of Blastocystis subtypes