A Line-free Method of Monopoles for 3D Dislocation Dynamics

We develop an approximation scheme for three-dimensional dislocation dynamics in which the dislocation line density is concentrated at points, or monopoles. Every monopole carries a Burgers vector and an element of line. The monopoles move according to mobility kinetics driven by elastic and applied forces. The divergence constraint, expressing the requirement that the monopoles approximate a boundary, is enforced weakly. The fundamental difference with traditional approximation schemes based on segments is that in the present approach an explicit linear connectivity, or 'sequence', between the monopoles need not be defined. Instead, the monopoles move as an unstructured point set subject to the weak divergence constraint. In this sense, the new paradigm is 'line-free', i. e., it sidesteps the need to track dislocation lines. This attribute offers significant computational advantages in terms of simplicity, robustness and efficiency, as demonstrated by means of selected numerical examples

Sintesis dan Karakterisasi Sifat Magnetik Serbuk Barium M-Heksaferrit dengan Doping Ion Zn pada Variasi Temperatur Rendah

Sintesis Barium M-Heksaferrit (BaFe11,4Zn0,6O19) doping ion Zn telah dilakukan dengan metode kopresipitasi. Bahan yang digunakan dalam sintesis yaitu BaCO­3, FeCl3.6H2O dan ion Zn. Dalam penelitian ini digunakan variasi suhu kalsinasi pada temperatur rendah yaitu 80oC, 150oC, 200oC dan 280oC selama 4 jam. Hasil sintesis dikarakterisasi dengan DSC-TGA (Differential Scanning Calorimetry – Thermogravimetric), XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy) dan VSM (Vibrating Sample Magnetometer). Barium M-Heksaferrit terbentuk pada temperatur 150oC sebesar 72,54% dan mempunyai ukuran partikel sebesar 0,5μm. Kurva histerisis menunjukkan telah terbentuk softmagnetic dengan magnetisasi remanensi (Mr) sebesar 0,01 emu/gr, medan koersivitas (Hc) sebesar 0,00825 Tesla dan mempunyai magnetisasi tertinggi terjadi ketika medan koersivitas (Hc) sebesar 1 Tesla dengan magnetisasi sebesar 0,55 emu/gr

The Development of E-governance-based Quality in the Universities

Universities hold a strategic role in society as the teaching university, the research university, and the bastion of civilization. In this decade, the challenges of the universities become more complex where a paradigm shift in the universities occur such as: (1) the shifting of the role of the universities due to the influence of the globalization; (2) the scarcity of resources in response to changes with the proper way; (3) the development of the science and technology which accelerates rapidly; and (4) the development of the rapid entrepreneurial culture. Some important and fundamental issues facing the universities college in Indonesia today is that the existence of the universities college in Indonesia still faces a number of obstacles in the policy, the implementation, the monitoring, and the evaluation. Moreover, the issue of quality and the relevance of outputs of the universities have not contributed optimally in the world of industry and society. The universities have not optimally been able to become the important sectorwhich can produce a significant number of entrepreneurs with the orientation of job creation and self-reliance. Based on the background of this grant research above, it can be concluded that the strategy of private universities towards the world class or high quality is studied. The method used was a qualitative research consisting of studying literature, conducting interviews, and distributing questionnaires to the informants in the universities in four provinces or cities in the area of The coordinator of The Private UniversitiesII of the southern sumatra and the analysis models. The following method used a quantitative method to measure the parameters of the performance of the universities and entrepreneurial growths of the universities. According to the results of the research in the first, second, and third year, a model to improve the e-governance-based quality to the universities through the research focus, the entrepreneurship, and the development of the resources was developed in the area of The coordinator of The Private Universities II of the southern sumatra. The final result of the improvement of e-governance-based quality in the universities in southern sumatra was the manifestation of the policy of the ministry of the higher education and research in implementing the management of the world-class universities, the scientific publications, and the reference textbooks

Comparative behaviour in terms of wear and corrosion resistance of galvanized and zinc-iron coated steels

Materials degradation due to simultaneous chemical and mechanical effects may occur under a variety of conditions. Galvanized and zinc-iron electrodeposited steels are widely used to protect automobile bodies against corrosion. In such applications, it is important to investigate the electrochemical and tribological behaviour of the coatings, in order to understand the behaviour of those surfaces in a tribological contact exposed to a corrosive environment. In the present paper, the evolution of open circuit potential, for both surfaces, was monitored during reciprocating sliding against an alumina pin in a 3% NaCl solution. The coatings are compared in terms of electrochemical behaviour by polarization tests, open circuit potential and friction coefficient during sliding; and loss of mass after sliding. The surface morphology, after sliding, was examined by SEM. Under the experimental conditions of the present study, the results found in terms of corrosion and wear resistance could be correlated to the differences in morphology, rugosity and composition of the two analysed surfaces.Capes Brasil.CNPq Brasil

Flow-injection analysis for on-line monitoring of nutrients (ammonia and nitrite) in aquaculture

This article describes photometric flow injection (FI) methods for the determination of ammonia and nitrite in aquaculture. The methods are based on the use of normal and reversed FI approaches and show the potential of this technique for monitoring the input and output streams of small tanks at young fish-breeding farms. The methods meet the requirements of fish hatcheries, particularly in terms of the high sampling rate allowable (40/h)