First-Principles Investigation of Perfect and Diffuse Anti-Phase Boundaries in HCP-Based Ti-Al Alloys

First-principles thermodynamic models based on the cluster expansion formalism, monte-carlo simulations and quantum-mechanical total energy calculations are employed to compute short-range-order parameters and diffuse-antiphase-boundary energies in hcp-based $\alpha$-Ti-Al alloys. Our calculations unambiguously reveal a substantial amount of SRO is present in $\alpha$-Ti-6 Al and that, at typical processing temperatures concentrations, the DAPB energies associated with a single dislocation slip can reach 25 mJ/m$^{2}$. We find very little anisotropy between the energies of DAPBs lying in the basal and prism planes. Perfect antiphase boundaries in DO$_{19}$ ordered Ti$_3$Al are also investigated and their interfacial energies, interfacial stresses and local displacements are calculated from first principles through direct supercell calculations. Our results are discussed in light of mechanical property measurements and deformation microstructure strudies in $\alpha$ Ti-Al alloys

Studi Sistem Drainase Resapan di Wilayah Karang Anyar Kota Tarakan

Tarakan City is one city that is often flooded during the rainy season it is in because of the narrow drainage system and due to the accumulation of garbage other than one of the factors that affect flooding is tidal. For the central Tarakan Region, specifically in the region of Karang Anyar Central Tarakan that is Seroja , Kenanga and mawar street flood that occurred due to the drainage system which is not good. And population growth is rapidly increasing and the growth of residential construction and industry as well as other supporting facilities are not balanced with the development of the drainage system. Increase the number of discharges that come out due to the increase of housing and other buildings are often already do not meet the capacity of its maximum capacity on existing drainage channels. The research is conducted by doing a survey in the field to obtain primary data and secondary data which will then be processed using the method ISO No. 03-2459-2002 about general and technical requirments infiltration wells, this standard is a revision of ISO No. 03-3459-2991. The result of the field trial showed that the infiltration rate as measured by the single ring infiltrometeron seroja street at 6cm/hour, on kenanga street by 6 cm/hour, and mawar street by 9cm/hour. Each infiltration wells are planned at each house is capable of reducing flood discharge as much as 0.00254m3/sec at seroja street, kenanga street 0.00282 m3/sec and 0.0034m3/sec on mawar street. Under the assumption 70 % of homes in the study area using infiltration wells

Surface energetics and structure of the Ge wetting layer on Si(100)

Ge deposited on Si(100) initially forms heteroepitaxial layers, which grow to a critical thickness of ~3 MLs before the appearance of three-dimensional strain relieving structures. Experimental observations reveal that the surface structure of this Ge wetting layer is a dimer vacancy line (DVL) superstructure of the unstrained Ge(100) dimer reconstruction. In the following, the results of first-principles calculations of the thickness dependence of the wetting layer surface excess energy for the c(4×2) and 4×6 DVL surface reconstructions are reported. These results predict a wetting layer critical thickness of ~3 MLs, which is largely unaffected by the presence of dimer vacancy lines. The 4×6 DVL reconstruction is found to be thermodynamically stable with respect to the c(4×2) structure for wetting layers at least 2 ML thick. A strong correlation between the fraction of total surface induced deformation present in the substrate and the thickness dependence of wetting layer surface energy is also shown

Structure, energetics, and mechanical stability of Fe-Cu bcc alloys from first-principles calculations

Atomic volumes, magnetic moments, mixing energies, and the elastic properties of bcc Fe1–xCux solid solutions are studied by ab initio calculations based on the cluster expansion framework. For the calculation of concentration-dependent elastic moduli in disordered solid solutions, we introduce a generalization of the cluster expansion technique that is designed to handle tensorial quantities in high-symmetry phases. Calculated mixing energies, atomic volumes, and magnetic moments are found to be in good agreement with available measurements for metastable alloys prepared through nonequilibrium processing techniques. Additionally, the predicted variations of the bulk modulus and shear moduli C44 and C[prime] with respect to copper concentration are calculated for the disordered bcc phase. While the bulk modulus and C44 are positive for all concentrations, C[prime] is predicted to be positive only for Cu concentration less than 50 atomic %, and negative otherwise. Our results thus indicate that the mechanical instability of bcc Cu persists over a wide range of compositions. The implications of the present results are discussed in relation to the observed metastability of bcc Fe-Cu alloys, and the strengthening mechanism of nanoscale bcc precipitates in an alpha-Fe matrix

Pengaruh Kepuasan Kerja dan Komitmen Organisasional terhadap Organizational Citizenship Behavior

The aim of this study was to examine the direct effect of job satisfaction and organizational commitment on organizational citizenship behavior. This research was conducted in LPD Desa Adat Kedonganan using all employees amounted to 49 people as respondent. Sampling technique used in this study are saturated sampling technique. Data collected through interviews and questionnaires. The data analysis technique used is multiple linear regression. This study found that job satisfaction has positive influence on organizational citizenship behavior. Organizational commitment has positive effect on organizational citizenship behavior. To improve organizational citizenship behavior, LPD Desa Adat Kedonganan are advised to increase job satisfaction, especially by gving promotion to the employees who have done a good job and demonstrated performance continues to increase each year. In addition, it is recommended to increase organizational commitment in a way to get closer to employees so that employees feel like family in LPD Desa Adat Kedonganan