The Gap-Tooth Method in Particle Simulations

We explore the gap-tooth method for multiscale modeling of systems represented by microscopic physics-based simulators, when coarse-grained evolution equations are not available in closed form. A biased random walk particle simulation, motivated by the viscous Burgers equation, serves as an example. We construct macro-to-micro (lifting) and micro-to-macro (restriction) operators, and drive the coarse time-evolution by particle simulations in appropriately coupled microdomains (teeth) separated by large spatial gaps. A macroscopically interpolative mechanism for communication between the teeth at the particle level is introduced. The results demonstrate the feasibility of a closure-on-demand approach to solving hydrodynamics problems

Constructing compact 8-manifolds with holonomy Spin(7) from Calabi-Yau orbifolds

Compact Riemannian 7- and 8-manifolds with holonomy G(2) arid Spin(7) were first constructed by the author in 1994-5, by resolving orbifolds T-7/Gamma and T-8/Gamma. This paper describes a new construction of compact 8-manifolds with holonomy Spin(7). We start with a Calabi-Yau 4-orbifold Y with isolated singularities of a special kind. We divide by an antiholomorphic involution a of Y to get a real 8-orbifold Z = Y/. Then we resolve tire singularities of Z to get a compact 8-manifold M, which has metrics with holonomy Spin(7). Manifolds constructed in this way typically have large fourth Betti number b(4)(M).</sigma

Simulation of granular soil behaviour using the bullet physics library

A physics engine is computer software which provides a simulation of certain physical systems, such as rigid body dynamics, soft body dynamics and fluid dynamics. Physics engines were firstly developed for using in animation and gaming industry ; nevertheless, due to fast calculation speed they are attracting more and more attetion from researchers of the engineering fields. Since physics engines are capable of performing fast calculations on multibody rigid dynamic systems, soil particles can be modeled as distinct rigid bodies. However, up to date, it is not clear to what extent they perform accurately in modeling soil behaviour from a geotechnical viewpoint. To investigate this, examples of pluviation and vibration-induced desification were simulated using the physics engine called Bullet physics library. In order to create soil samples, first, randomly shaped polyhedrons, representing gravels, were generated using the Voronoi tessellation approach. Then, particles were pluviated through a funnel into a cylinder. Once the soil particles settled in a static state, the cylinder was subjected to horizontal sinusoidal vibration for a period of 20 seconds. The same procedure for sample perparation was performed in the laboratory. The results of pluviation and vibration tests weere recorded and compared to those of simulations. A good agreement has been found between the results of simulations and laboratory tests. The findings in this study reinforce the idea that physics engines can be employed as a geotechnical engineering simulation tool

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Eating | Maki YagiEcology | Andrew BiroE-mail | Janine MarchessaultEnd | Scott MacKenzieEnthusiasm | Olivier AsselinEntrance | Ken AllanEurocentrism | Cornel WestExile | Janine Marchessaul

Monetary Instruments and the Control of Liquidity in the Philippines: Focus on Open Market Operations

Monetary policies refer to the actions of central banks aimed to achieve macroeconomic stability and to influence financial factors such as money and interest rate. This paper discusses the framework for analyzing how monetary instruments affect monetary targets and the advantages and disadvantages of various instruments dispensable by the central bank. It also argues for the use of open market operations.central bank, money and banking, financial system, financial stabilization, monetary policy, open market operations, monetary instruments

Thirty-Three Facts About Philippine Agricultural Credit

This paper is an edited and expanded version of PIDS Staff Paper 87-02. It provides a number of facts and observations regarding agricultural credit, the main source of which is the ongoing program to rehabilitate the rural banks, to re-orient the concept of supervised credit and the creation of the Comprehensive Agricultural Loan Fund. This article also includes the 20-year experience of the Philippines and other selected countries in rural banking and agricultural credit.agriculture sector, banking system, rural sector, credit market

Survey and Assessment of Laws on the Informal Sector

This study classifies the laws affecting the informal sector and assesses the extent of the empowerment of the sector based on the provisions in the laws that allow for organization, decision making mechanisms and transfer of power from the traditional center to another. Results indicate that, to some extent, four groups within the sector are accorded empowerment through Philippine laws: the agricultural sector, small and medium enterprises, industrial home workers and cooperatives. These groups are allowed to form organizations and to participate in decision making bodies. Decision making is accorded to certain groups among informal sector, which, in some cases, comprise the majority members in decision making bodies. Nowhere among the laws is a shift of power provided from the traditional or government decision makers to the informal sector. However, certain groups within the IS have participated in the institution of some policies and the realization of programs for their own advantage.informal financial sectors, small and medium enterprises

Currency Devaluations, Product Pricing and Trade Deficits

This paper explains why currency movements and trade volumes, while theoretically related, have minimal effect on each other, in practice. In addition, it argues that volatile currency movements and trade deficits are not beneficial in the long run. A separate set of measures on how to deal with each issue is also discussed.trade sector, devaluation, foreign exchange liberalization, currency and banking crisis

Survey and Assessment of Laws on the Informal Sector

This study classifies the laws affecting the informal sector and assesses the extent of the empowerment of the sector based on the provisions in the laws that allow for organization, decision making mechanisms and transfer of power from the traditional center to another. Results indicate that, to some extent, four groups within the sector are accorded empowerment through Philippine laws: the agricultural sector, small and medium enterprises, industrial home workers and cooperatives. These groups are allowed to form organizations and to participate in decision making bodies. Decision making is accorded to certain groups among informal sector, which, in some cases, comprise the majority members in decision making bodies. Nowhere among the laws is a shift of power provided from the traditional or government decision makers to the informal sector. However, certain groups within the IS have participated in the institution of some policies and the realization of programs for their own advantage.informal financial sectors, small and medium enterprises