Analisa Teknis Dan Ekonomis Pemilihan Manajemen Air Ballas Pada Kapal (Ship Ballast Water Management) Di Indonesia

Peraturan yang mengatur dan manajemen dari air ballas dikeluarkan oleh IMO (International Maritime Organization) melalui konvensi Manajemen air ballas. Konvensi tersebut menyatakan bahwa organisme yang berbahaya terhadap lingkungan, kesehatan manusia, properti atau sumber daya merusak keanekaragaman hayati atau mengganggu pemanfaatan terhadap suatu area jika dilepaskan di air laut. Pemerintah Republik Indonesia mengeluarkan Peraturan Presiden No. 132 tahun 2015 mengenai pengesahan Konvensi Internasional untuk pengendalian dan manajemen air ballas dan sedimen dari kapal 2004 (The International Convention for the control and management of ships ballast water and sediment's 2004). Penelitian ini bertujuan untuk menganalisa sejauh mana kesiapan Indonesia dalam ratifikasi peraturan (come into force) Ballast water Management serta dampak yang diakibatkan setelah peraturan tersebut diratifikasi. Metode yang dilakukan dalam penelitian ini menggunakan 3 pendekatan yaitu dari aspek hukum, aspek teknis dan aspek ekonomis. Hasil dari penelitian ini adalah Peraturan Pemerintah Nomor 21 Tahun 2010 tentang Perlindungan Lingkungan Maritim sebagai jabaran dari Undang-Undang Nomor 17 Tahun 2008 tentang Pelayaran, telah sejalan dengan Konvensi Internasional untuk Pengendalian dan Manajemen Air Ballas dan Sedimen dari Kapal, 2004 dan Undang-Undang Nomor 17 Tahun 1985 tentang pengesahan United Nations Convention on the LAW of the Sea (UNCLOS). Serta Penggunaan sistem manajemen air ballas untuk kapal di perairan Indonesia lebih efektif dan efisien menggunakan filtration + electrolysi

A quantitative theory of current-induced step bunching on Si(111)

We use a one-dimensional step model to study quantitatively the growth of step bunches on Si(111) surfaces induced by a direct heating current. Parameters in the model are fixed from experimental measurements near 900 deg C under the assumption that there is local mass transport through surface diffusion and that step motion is limited by the attachment rate of adatoms to step edges. The direct heating current is treated as an external driving force acting on each adatom. Numerical calculations show both qualitative and quantitative agreement with experiment. A force in the step down direction will destabilize the uniform step train towards step bunching. The average size of the step bunches grows with electromigration time as t^beta, with beta = 0.5, in agreement with experiment and with an analytical treatment of the steady states. The model is extended to include the effect of direct hopping of adatoms between different terraces. Monte-Carlo simulations of a solid-on-solid model, using physically motivated assumptions about the dynamics of surface diffusion and attachment at step edges, are carried out to study two dimensional features that are left out of the present step model and to test its validity. These simulations give much better agreement with experiment than previous work. We find a new step bending instability when the driving force is along the step edge direction. This instability causes the formation of step bunches and antisteps that is similar to that observed in experiment.Comment: 11 pages, 7 figure

Micro-Capsules in Shear Flow

This paper deals with flow-induced shape transitions of elastic capsules. The state of the art concerning both theory and experiments is briefly reviewed starting with dynamically induced small deformation of initially spherical capsules and the formation of wrinkles on polymerized membranes. Initially non-spherical capsules show tumbling and tank-treading motion in shear flow. Theoretical descriptions of the transition between these two types of motion assuming a fixed shape are at variance with the full capsule dynamics obtained numerically. To resolve the discrepancy, we expand the exact equations of motion for small deformations and find that shape changes play a dominant role. We classify the dynamical phase transitions and obtain numerical and analytical results for the phase boundaries as a function of viscosity contrast, shear and elongational flow rate. We conclude with perspectives on timedependent flow, on shear-induced unbinding from surfaces, on the role of thermal fluctuations, and on applying the concepts of stochastic thermodynamics to these systems.Comment: 34 pages, 15 figure

Persistence and survival in equilibrium step fluctuations

Results of analytic and numerical investigations of first-passage properties of equilibrium fluctuations of monatomic steps on a vicinal surface are reviewed. Both temporal and spatial persistence and survival probabilities, as well as the probability of persistent large deviations are considered. Results of experiments in which dynamical scanning tunneling microscopy is used to evaluate these first-passage properties for steps with different microscopic mechanisms of mass transport are also presented and interpreted in terms of theoretical predictions for appropriate models. Effects of discrete sampling, finite system size and finite observation time, which are important in understanding the results of experiments and simulations, are discussed.Comment: 30 pages, 12 figures, review paper for a special issue of JSTA

Amoeboid motion in confined geometry

International audienceMany eukaryotic cells undergo frequent shape changes (described as amoeboid motion) that enable them to move forward. We investigate the effect of confinement on a minimal model of amoeboid swimmer. A complex picture emerges: (i) The swimmer's nature (i.e., either pusher or puller) can be modified by confinement, thus suggesting that this is not an intrinsic property of the swimmer. This swimming nature transition stems from intricate internal degrees of freedom of membrane deformation. (ii) The swimming speed might increase with increasing confinement before decreasing again for stronger confinements. (iii) A straight amoeoboid swimmer's trajectory in the channel can become unstable, and ample lateral excursions of the swimmer prevail. This happens for both pusher- and puller-type swimmers. For weak confinement, these excursions are symmetric, while they become asymmetric at stronger confinement, whereby the swimmer is located closer to one of the two walls. In this study, we combine numerical and theoretical analyses

Deep Tillage Improves Degraded Soils in the (Sub) Humid Ethiopian Highlands

Intensification of rainfed agriculture in the Ethiopian highlands has resulted in soil degradation and hardpan formation, which has reduced rooting depth, decreased deep percolation, and increased direct runoff and sediment transport. The main objective of this study was to assess the potential impact of subsoiling on surface runoff, sediment loss, soil water content, infiltration rate, and maize yield. Three tillage treatments were replicated at five locations: (i) no tillage (zero tillage), (ii) conventional tillage (ox-driven Maresha plow, up to a depth of 15 cm), and (iii) manual deep ripping of the soil’s restrictive layers down to a depth of 60 cm (deep till). Results show that the posttreatment bulk density and penetration resistance of deep tillage was significantly less than in the traditional tillage and zero-tillage systems. In addition, the posttreatment infiltration rate for deep tillage was significantly greater, which resulted in significantly smaller runoff and sedimentation rates compared to conventional tillage and zero tillage. Maize yields were improved by 6% under deep tillage compared to conventional tillage and by 29% compared to no tillage. Overall, our findings show that deep tillage can be effective in overcoming some of the detrimental effects of hardpans in degraded soils

Current-Induced Step Bending Instability on Vicinal Surfaces

We model an apparent instability seen in recent experiments on current induced step bunching on Si(111) surfaces using a generalized 2D BCF model, where adatoms have a diffusion bias parallel to the step edges and there is an attachment barrier at the step edge. We find a new linear instability with novel step patterns. Monte Carlo simulations on a solid-on-solid model are used to study the instability beyond the linear regime.Comment: 4 pages, 4 figure

Formation of disclination lines near a free nematic interface

We have studied the nucleation and the physical properties of a -1/2 wedge disclination line near the free surface of a confined nematic liquid crystal. The position of the disclination line has been related to the material parameters (elastic constants, anchoring energy and favored anchoring angle of the molecules at the free surface). The use of a planar model for the structure of the director field (whose predictions have been contrasted to those of a fully three-dimensional model) has allowed us to relate the experimentally observed position of the disclination line to the relevant properties of the liquid crystals. In particular, we have been able to observe the collapse of the disclination line due to a temperature-induced anchoring angle transition, which has allowed us to rule out the presence of a real disclination line near the nematic/isotropic front in directional growth experiments. 61.30.Jf,61.30.G

Alveolar Bone Regeneration Via Utilization of Nanohydroxyapatite Scaffolds: A Review

The complete architectural and functional rehabilitation of periodontium owes to the integrity of alveolar bone. The inherent shortcomings of traditional gold standard regenerative procedures like autografting, xenografting, allografting and alloplasting lead to the evolutionary combination of Tissue Engineering/Regenerative Medicine (TE/RM) and nanotechnology for bone repair. Nanotechnology enables the fabrication of either nanoparticles, nanofibers or nanocomposites based on three-dimensional scaffolds. However, it will incorporate vital cells and growth factors in various combinations, to simulate a conducive oral environment of the extracellular matrix (ECM) and empower cells in the bone to regulate in-vivo osteogenesis. The advantageous combination of structural similarity of nanohydroxyapatite (nHA) Scaffolds to the alveolar bone with favorable particle size, response rate, tissue factors and bio factor, makes it attractive for TE/RM. Relevant keywords from 2010-2021 studies were used to retrieve data from “PubMed” and “Google Scholar”. This review aims to summarize the cumulative knowledge of commercially available nanohydroxyapatite scaffolds for utilization in alveolar bone augmentation, regeneration of implant osteointegration by their fabrication techniques, advantages, components, types, interaction with various components and particular application of each type for in vivo alveolar bone regeneration. Therefore, nHA scaffolds possess significant osteoconductive and osteoinductive effects on structural similarities to the composition, adhesion and differentiation of bone-forming cells. Keywords: Scaffolds; Tissue Engineering; Nano-Hydroxyapatite, Bone Regeneration; Nanotechnology