Kekasaran Dan Morfologi Hasil Pengelasan TIG Baja Tahan Karat 316 Dengan Kadar Sulfur Berbeda

The presence of impurities in stainless steel can unexpectedly create a problem in welding. The difference of a small amount of impurities, from heat to heat, can induce the inconsistency in welding especially in automatic welding. This study is conducted to asses the influence of sulfur content of the steel on morphology of weld which is represented by the variation of weld pool and surface roughness of weld. The effect of sulfur on surface roughness of weld is studied in TIG welding of 316 stainless steels with different sulfur content. The influence of sulfur on the weld geometry, characterized by the ratio of depth and width of the weld (D/W), is studied in welding with various parameters. The variation of the weld geometry is conjointly studied in relation to the surface roughness of weldment. The effect of sulfur is also studied using a stationary arc with different current and duration. The variation of the diameter of a circular pool and the degree of protuberance which possibly emerged beneath the specimen is related to the sulfur content of the steel. The results of the study show the salient effect of sulfur on the surface roughness of weld. The surface roughness of steel with high sulfur content always more perturbed than that of steel with lower one; the different movement of liquid, characteristic of these two steels is posited to explain the difference. Greater degree of roughness is accompanied by a greater value of the ratio D/W. The results of the study with stationary arc show some points of a paramount importance. The effect of sulfur which hitherto considered advantageous to the formation of a weld with a higher ratio of D/W, turn out to be effective only in a specific range of welding parameters. In a different range, the weld geometry is more influenced by the arc characteristic, the anode spot

Dopant Induced Stabilization of Silicon Cluster at Finite Temperature

With the advances in miniaturization, understanding and controlling properties of significant technological systems like silicon in nano regime assumes considerable importance. It turns out that small silicon clusters in the size range of 15-20 atoms are unstable upon heating and in fact fragment in the temperature range of 1200 K to 1500 K. In the present work we demonstrate that it is possible to stabilize such clusters by introducing appropriate dopant (in this case Ti). Specifically, by using the first principle density functional simulations we show that Ti doped Si$_{16}$, having the Frank-Kasper geometry, remains stable till 2200 K and fragments only above 2600 K. The observed melting transition is a two step process. The first step is initiated by the surface melting around 600 K. The second step is the destruction of the cage which occurs around 2250 K giving rise to a peak in the heat capacity curve.Comment: 6 pages, 8 Figs. Submitted to PR

Indirect Photometric Chromatography of Inorganic and Organic Anions Using Benzoate as an Eluent

For many years the determination of common inorganic and organic anions was hindered by the lack of adequately sensitive analytical techniques. The determination of these anions was laborious and time consuming (e.g. titration, precipitaion, gravimetric analysis etc.). Because of the development of high-performance liquid chromatography, the anion exchange separation of simple inorganic and organic anions is now possible. Now, there are a broad and ever-increasing array of chromatographic methods supplanting these older chemical methods. However, detection is still a problem, but indirect detection provides a practical route for the detection of non-chromophoric inorganic and organic anions. This dissertation describes the technique of Indirect Photometric Chromatography (IPC) for the determination of common inorganic anions and short-chain carboxylic and sulfonic acids. In this study, inverted peaks were observed in an elevated baseline as the transparent sample ions were selectively displaced from the anion exchange column by the UV absorbing mobile phase ion sodium benzoate. A Hamilton PRP-X100 (styrene-divinyl benzene) anion exchange column which possessed a low capacity and a wide working pH range (1-13) was employed. The influence of various mobile phase parameters such as benzoate concentration, pH, and percent organic content was investigated. A 2.0 mM concentration of sodium benzoate provided maximum eluting ability for the separation of common inorganic anions (F-, Cl-, Br-, NO2-, NO3-, and H2PO4- ) within eight minutes with UV detection at 260 nm. At high pH, the competition between hydroxide and benzoate ions in the elution process decreases the detection sensitivity. Multicomponent mixtures of straight-chain alkyl carboxylic and sulfonic acids in the anionic form were also separated upon the addition of acetonitrile to the mobile phase. Combined anion exchange/reversed phase interactions were found to influence the retention of these organic acids. The application of the benzoate eluent with UV detection method to the determination of anions was demonstrated via the analysis of chloride, EDTA and sorbate in a commercial saline solution. The limits of detection for injected chloride and EDTA were 1.5 ppm, while sorbate was detected at 0.5 ppm

Indirect Photometric Chromatography of Inorganic and Organic Anions Using Benzoate as an Eluent

For many years the determination of common inorganic and organic anions was hindered by the lack of adequately sensitive analytical techniques. The determination of these anions was laborious and time consuming (e.g. titration, precipitaion, gravimetric analysis etc.). Because of the development of high-performance liquid chromatography, the anion exchange separation of simple inorganic and organic anions is now possible. Now, there are a broad and ever-increasing array of chromatographic methods supplanting these older chemical methods. However, detection is still a problem, but indirect detection provides a practical route for the detection of non-chromophoric inorganic and organic anions. This dissertation describes the technique of Indirect Photometric Chromatography (IPC) for the determination of common inorganic anions and short-chain carboxylic and sulfonic acids. In this study, inverted peaks were observed in an elevated baseline as the transparent sample ions were selectively displaced from the anion exchange column by the UV absorbing mobile phase ion sodium benzoate. A Hamilton PRP-X100 (styrene-divinyl benzene) anion exchange column which possessed a low capacity and a wide working pH range (1-13) was employed. The influence of various mobile phase parameters such as benzoate concentration, pH, and percent organic content was investigated. A 2.0 mM concentration of sodium benzoate provided maximum eluting ability for the separation of common inorganic anions (F-, Cl-, Br-, NO2-, NO3-, and H2PO4- ) within eight minutes with UV detection at 260 nm. At high pH, the competition between hydroxide and benzoate ions in the elution process decreases the detection sensitivity. Multicomponent mixtures of straight-chain alkyl carboxylic and sulfonic acids in the anionic form were also separated upon the addition of acetonitrile to the mobile phase. Combined anion exchange/reversed phase interactions were found to influence the retention of these organic acids. The application of the benzoate eluent with UV detection method to the determination of anions was demonstrated via the analysis of chloride, EDTA and sorbate in a commercial saline solution. The limits of detection for injected chloride and EDTA were 1.5 ppm, while sorbate was detected at 0.5 ppm

Desert Power: Exploring How Jordan Can Democratize Through Tribalism

This independent study project will analyze tribal institutions in Jordan to understand how conducive they are to democracy. In the wake of the Arab Spring and the collapse of many burgeoning democracies in the Middle East, it is important to find ways in which pro-democracy advocates can build strong democratic states in the Middle East. Democracy allows a polity to choose who rules them. Furthermore, it has proven that peopling living in a democracy live longer, more fulfilling lives than those who do not. Given Jordan’s unique history as a stable regime with a strong tribal tradition, the researcher has chosen Jordan as his field site to conduct this research. Using qualitative methods, the researcher has concluded that the best way to ensure this democratization takes place in Jordan is if pro-democracy advocates build an inclusive system around tribalism, specifically, the tribal mediation process. While the researcher has found that the structures of tribalism itself may be incompatible with democracy, he has established that the values derived from the tribal mediation process such as transparency, reliance and accessibility ought to be incorporated in a democracy