Hasil Pencarian  ::  Simpan CSV :: Kembali

"A range of microstructure as a result of low-temperature crystallization of amorphous alloy based on the composition Fe68Cr18Mo2B12 prepared by chill block melt spinning casting has been investigated using x-ray diffractometer and transmission electron microscope. Low-temperature crustallization of the amorphous alloy produced a very fine microstructure consisting of Fe; body centered tetragonal Fe3B and a small proportion of orthorhombic Fe3B. The body centered tetragonal Fe3B was found to contain fine and coarse faults with lead to streaking in selected area diffraction patterns. The crystallization of the present material is proposed to occur by primary crystallization of solid solution ferritic phase followed by a eutectic reaction of Fe+Fe3B."

"Tujuan utama tesis ini adalah untuk mengetahui pola perdagangan saham intrahari ditinjau dari return dan volatilitasnya, mengetahui adanya day of the week effect dan time of the day effect serta melihat perbedaan return antar hari perdagangan dan antar interval waktu 30 menit pada 5 fraksi perdagangan di Bursa Efek Indonesia. Hasil penelitian ini menunjukkan bahwa return kelima kelompok fraksi perdagangan membentuk kurva yang tidak seragam. Return kelompok fraksi perdagangan Rp1 membentuk kurva W, kelompok fraksi perdagangan Rp5, Rp10 dan Rp25 membentuk kurva J sedangkan kelompok fraksi perdagangan Rp50 membentuk kurva U. Ditinjau dari volatilitasnya, kelima kelompok fraksi perdagangan membentuk kurva yang sama yaitu kurva U. Dengan adanya perbedaan pola perdagangan ini maka investor dapat menetapkan strategi investasi yang tepat yaitu waktu terbaik untuk melakukan transaksi (buy/sell) dan kelompok fraksi saham yang direkomendasi dan yang dihindari. Selain itu penelitian ini juga membuktikan adanya pengaruh signifikan dari pergerakan return saham baik berdasarkan periode hari maupun interval waktu 30 menit terhadap return saham. Dengan demikian hal ini membuktikan adanya day of the week effect dan time of the day effect pada semua kelompok fraksi perdagangan. Penelitian ini juga membuktikan adanya perbedaan return yang signifikan baik antar hari perdagangan maupun antar interval waktu 30 menit.

---

The main objective of this thesis is to determine stocks Intraday trading patterns in terms of returns and volatility by examining the day of the week effect and time of the day effect as well as investigating the return difference among trading days and among interval of 30 minutes for 5 fractions of trading in the Indonesia Stock Exchange.

The results indicate the return curves of the five trade fractions group are not similar. The returns of trade fraction group Rp1 form W-curve, trade faction group Rp5, Rp10 and Rp25 form J-curve, while trade fraction group Rp50 form the U-curve. However, the volatility of the five groups forms identical curve that is U-curve. By taking into account the differences in the pattern of trade, investor can determine proper investment strategy that is the best time to do the transaction (buy/sell) and the fraction of shares that are recommended and which to avoid.

In addition, this study demonstrates the existence of significant influence from either the movement of stock returns based on the period of the day and 30-minute intervals of stock return. Thus, the evidence supports the existence of day of the week effect and time of the day effect on all groups of trading fraction. The findings show the existence of significant return differences either between day trading and inter-interval time of 30 minutes."

"Perubahan struktur mikro baja karbon rendah menyebabkan terjadinya perubahan sifat. Perubahan ini sangat dipengaruhi oleh bentuk dan jenis pengerjaan (perlakuan) yang diberikan atau yang dialami oleh baja tersebut, bentuk dan jenis pengerjaan umumnya berupa pengerjaan panas atau pengerjaan dingin. Telah dilakukan penelitian pada konstruksi sambungan las dari bahan lembaran baja karbon rendah spesifikasi Ship Plate BKI Grade "A" hasil pengerolan panas produksi PT. Krakatau Steel, dengan menggunakan las SMAW dalam kondisi arus dan kecepatan pengelasan yang konstan. Dalam penelitian ini diambil dua jenis spesimen yang berbeda masing-masing spesimen yang tidak mengalami proses pengelasan dengan variasi sudut antara arah roll dan arah sumbu panjang spesimen masing-masing diambil 0° , 45° dan 90° dan spesimen yang mengalami proses pengelasan dengan variasi sudut arah roll terhadap arah las, masing-masing diambil 0° , 45° dan 90°.Pada penelitian ini dilakukann pengujian mekanik antara lain uji tarik, uji kekerasan, uji impact, pengukuran besar butir, uji metalografi, uji kekasaran permukaan, uji korosi serta struktur fasa dan bentuk butir. Berdasarkan hasil pengujian tersebut diatas didapatkan kekuatan tarik terbesar (6u) = 46,33 kg/mm2, kekuatan luluh (ay) = 31,74 kg/mm2 elongation (e) = 41,66 %, kekuatan impact (HI) = 1,525 J/mm2, kekerasan (Hv) = 200 pengurangan massa (R) = 1,212 mm/yr dan kekuatan tarik terkecil (6u) = 37,76 kglmm2, kekuatan luluh (ay) = 27,02 kg/mrn2, elongation (e) = 09,50 %, kekerasan (Hv) = 160,70, kekuatan impak (HI) = 0,0128 J/mm2 dan pengurangan massa (R) = 0,0641 mm/yr.

---

The change of microstructure low carbon steel to cause alteration property. This alteration very influenced by model treatment quality which receiving or to experienced by steel mentioned this type or sort working was generally hot working which cold working. The investigation or-welding joint construction according to material low carbon steel spesification "Ship Plate BKI Grade A" hot rolling produce PT. Krakatau steel with applying SMAW weld in current condition and welding speed which constant According to investigation used two speciment type which to differ severally that not to experience welding proms for angle variation direction gap to rolling and and length pith speciment to take severally 0°, 45° and 90° and the speciment which to experience welding process with rolling direction to wards weld metal course, for severally to used 0°, 45° dan 90°.

According to this investigation to executed mechanic testing among ather things tension test, hardness test impact test grain measuring, metallography test surface roughness test and corrosion test, besides from that possible too grain model and fasa structure° To be found result test mentioned to find the highest tension stress (au) = 46,33 kg/mm2, yield stress (cy) = 31,74 kglmm2, elongation (e) = 41,66 %, impact stress (Hi) = 1,525 J/mm2, hardness (Hv) = 2110 and to decrease of mass (R) = 1,212 mm/yr, and the lowest tension stress (cu) = 37,76 kg/mm2, yield stress (ay) = 27,02 kg/mm2, elongation (e) = 09,50 %, hardness (Hv) = 160,70, impact stress (HI) = 0,0128 J/mm2, and to decrease of mass (R) = 0,0641 mm/yr."

"Research sintering effect on the micro structure and the magnetic properties of composite Co-AlxOy materials hs been done

---

"

"Microstructure observation, chemical composition and hardness of Al-6061 alloy welding result. The microstructure observation, chemical composition and hardness of Al-6061 alloy welding result has been done. Two Al6061 alloy plates were welded by usingGTAW and the Al-4043 alloy as filler..."

"ABSTRAKAlloy FeSi adalah material softmagnetik yang banyak digunakan sebagai inti dalam transformator. Material ini memiliki sifat yakni magnetisasi saturasinya tinggi, koersivitasnya rendah, permeabilitasnya tinggi. Bertambahnya Si akan mengurangi koersivitas dan meningkatkan resistivitas sehingga core loss akibat hysterisis dan Eddy current menurun, dan didapatkan sifat magnetik material yang baik untuk apikasi transformer. Tetapi penambahan Si diatas 3 % menyebabkan alloy bersifat brittle. Penambahan Al pada alloy FeSi diharapkan dapat memperbaiki sifat magnetik dan sifat mekanik, sehingga efisiensi dari transformator dapat meningkat. Untuk itu dilakukan penelitian studi sifat magnetik beserta komposisi dan mikrostruktur dari FeSiAl. Dengan kadar Si 3% dan variasi kadar Al 4%,5% dan 6% serta kadar Fe100-3%-%Al . Dalam penelitian ini sifat magnetik yang diukur adalah koersivitas yang diperoleh dari hysterisis loop. dengan menggunakan alat VSM (Vibrating sample magnetometer). Dari hasil penelitian ini tampak bahwa koersivitas menurun dengan pertambahan Al yang berarti sifat magnetiknya lebih baik. Mikro struktur material diteliti dengan menggunakan XRD dan foto mikro yang menunjukkan fasa ketiga sampel sebagai body centered cubic.

---

ABSTRAK

The alloy FeSi is a softmagnetic material oftenly used as the core component of a transformer. This material has the properties of high saturation of magnetization, low coercivity and high permeability. Increased Si will reduce the coercivity and increase the resistance, so there is a reduction of core loss due to hysterisis and eddy current?properties of magnetic material that is good for application in transformers. But increasing Si more than 3% causes the alloy to become brittle. Adding aluminium to FeSi is hoped to improve the magnetic and mechanical properties of the alloy, so as to increase the efficiency of a transformer. To achieve the aims, a research was carried out to study the composition and microstructure of FeSiAl, with 3% Si concentration and varied concentrations of aluminium (4%, 5% and 6%), and Fe100-3%-%Al concentration. In this research, the magnetic property measured was coercivity obtained from loop hysterisis using VSM (vibrating sample magnetometer). In the research, it was observed that coercivity was reduced with the addition of Al, which means the alloy had better magnetic properties. The microstructure of the material was studied using XRD and microphotograph that showed the phase of the three samples as being body-centered cubic."

"The present work observed the evolution of microstructure in an Al-4Cu-0.3Mg-0.5Cd (wt. %) alloyaged at 200 °?C. The precipitation sequence in this alloy was found to be dominated by the binary Al-Cualloy classical transformation, ie: GP zones -> 0" -> 0' -> ) Analytical transmission electron microscoperevealed that elemental Cd precipitates formed at later stages of ageing. These precipitates wereassociated with the 6' platelets, both on the rim and the broad facet of the precipitates. Small precipitateswith similar morphology with the Cd precipitates were also observed at the early stages of ageing. Thesesuggest that the Cd precipitates provide sites for 8' to nucleate, resulting in an increased dispersion of 6'.On the other hand these also suggest that Cd nucleates heterogeneouslv at the 0 / a interface."

"Boron liquid metal ion sources (LMIS) for focused ion beam system have been developed in the form of binary eutectic alloy of Pd73B27. This alloy source was selected as a p-type dopant source. A source life time of more than 120 h has been recorded with different emitter tip radii to test boron ion beam stability. Microstructure examination of the Pd73B27 binary alloy proved that boron LMIS instability was cause primarily by the formation of solid precipitates due to a change in alloy stoichiometry. Auger electron spectroscopy (AES) analysis of boron beam deposited on a flat silicon substrate shows rhenium emitter erosion as well as other elements (Fe, Ni and Cr) resulting from extractor sputtering. Greater attention was paid on the metallurgical aspect of LMIS to develop more reliable boron LMIS.

---

Sumber ion metal cair boron untuk sistem berkas ion terpusat telah dibuat dengan menggunakan paduan biner "eutectic" Pd73B27- Sumber berkas ion dari paduan ini dipilih sebagai sumber dopan jenis p. Masa pakai paduan lebih dari 120 jam telah dicatat dengan percobaan menggunakan berbagai ukuran jari-jari emiter untuk mengukur kestabilan dari berkas ion yang berbasis boron. Penyelidikan terhadap struktur mikro dari paduan biner Pd73B27 membuktikan bahwa ketidak stabilan dari sumber ion metal cair berbasis boron disebabkan oleh pembentukan presipitat padatan. Pembentukan presipitat padatan ini akibat dari perubahan "stoichiometry". Analisa dengan menggunakan spektroskopi Auger dengan cara mendipositkan berkas ion ini pada permukaan lempeng silikon yang rata membuktikan bahwa terjadi erosi emiter yang terbuat dari rhenium dan juga elemen lain akibat dari pengaruh "sputtering" ekstraktor. Perhatian pada penelitian ini ditujukan pada aspek metalurgi dari sumber berkas ion metal cair untuk mengembangkan sumber ion metal cair boron yang dapat diandalkan."