Refined Meshless Local Strong Form solution of Cauchy-Navier equation on an irregular domain

This paper considers a numerical solution of a linear elasticity problem, namely the Cauchy-Navier equation, using a strong form method based on a local Weighted Least Squares (WLS) approximation. The main advantage of the employed numerical approach, also referred to as a Meshless Local Strong Form method, is its generality in terms of approximation setup and positions of computational nodes. In this paper, flexibility regarding the nodal position is demonstrated through two numerical examples, i.e. a drilled cantilever beam, where an irregular domain is treated with a relatively simple nodal positioning algorithm, and a Hertzian contact problem, where again, a relatively simple h-refinement algorithm is used to extensively refine discretization under the contact area. The results are presented in terms of accuracy and convergence rates, using different approximations and refinement setups, namely Gaussian and monomial based approximations, and a comparison of execution time for each block of the solution procedure.Comment: 19 pages, 16 figure

Has Private Participation in Water and Sewerage Improved Coverage? Empirical Evidence from Latin America

Introducing private sector participation (PSP) into the water and sewerage sectors in developing countries is difficult and controversial. Empirical studies on its effects are scant and generally inconclusive. Case studies tend to find improvements in the sector following privatization, but they suffer from selection bias and it is difficult to generalize from their results. To explore empirically the effects of PSP, we assemble a new dataset of connections to water and sewerage services at the city and province level based on household surveys in Argentina, Bolivia, and Brazil. The household surveys, conducted over a number of years, allow us to compile data before and after the introduction of PSP as well as from similar (control) regions that never privatized at all. Our analysis reveals that, in general, connection rates to piped water and sewerage improved following the introduction of PSP, consistent with the case study literature. We also find, however, that connection rates similarly improved in the control regions, suggesting that PSP, per se, may not have been responsible for those improvements. On the other hand, connection rates for the poorest households also tended to increase in the regions with PSP and in the control regions, suggesting that ,in terms of connections at least, PSP did not harm the poor.

Politics and preschool : the political economy of investment in pre-primary education

What drives governments with similar revenues to publicly provide very different amounts of goods for which private substitutes are available? Key examples are education and health care. This paper compares spending by Brazilian municipalities on pre-primary education -- a good that is also provided privately -- with spending on public infrastructure like parks and roads, which lacks private substitutes. Panel data from 1995-2008 reveal how the distribution of income affects public investment. Revenue is endogenous to investment outcomes, and the analysis addresses this problem by exploiting a 1998, nationwide education finance reform and several revisions to the policy. The author constructs a variable that captures exogenous variation in revenue generated by nonlinearities of the law to instrument for observed revenue. Municipalities with higher median income and more inequality are less likely to allocate revenue to education or to expand pre-primary enrollment. They are more likely to allocate revenue to public infrastructure. There is suggestive evidence that this occurs for two reasons, hypothesized in two separate literatures. In rich and unequal municipalities, fewer total people support public education spending (the collective choice channel), and also, any given poor person wanting public education has less influence over policymakers there (the political power channel).Public Sector Management and Reform,Public Sector Economics,Primary Education,Access to Finance,Regional Governance

Cracking of an Aircraft Wheel Rim Made From Al-Alloy 2014-T6

Generally failures of different aircraft components and parts are revealed and examined by the use of non-destructive examination methods. In further detailed explanation and interpretation of failures optical and scanning electron microscopy are used. This paper deals with a problem of a crack on aircraft wheel rim made from aluminium alloy 2014-T6.The crack was observed during regular control by the maintenance unit for non-destructive examination of the Slovenian air carrier Adria Airways. The crack on the rim of an aircraft wheel investigated was a typical fatigue crack. At same time a numerous pits were found which served as stress concentrations on the rim surface

The Economic Costs of the War in Iraq

Government policies are routinely subjected to rigorous cost analyses. Yet one of today’s most controversial and expensive policies—the ongoing war in Iraq—has not been. The $212 billion allocated by the U.S. Treasury has been widely reported. But the real, direct economic costs include more than budgetary allocations. Other costs include lives lost, injuries, and lost civilian productivity of National Guard and Reserve troops mobilized for the conflict. The conflict, however, also has generated cost savings, especially in terms of resources no longer being used to enforce UN sanctions and people no longer being killed by Saddam Hussein’s regime. In this paper we monetize these direct costs and avoided costs of the war in Iraq, both to-date and the total expected net present value of costs through 2015. Our estimates are imprecise. The data are not of high quality and every calculation requires a number of assumptions. In addition, we do not calculate indirect effects of the conflict, such as its impact on oil prices or other macroeconomic impacts, or certain intangibles, like the benefits of a stable democratically elected government in Iraq, should one emerge. Nonetheless, our best estimates suggests that the direct economic costs to the U.S. through August 2005 are about$255 billion, about $40 billion to coalition partners, and$134 billion to Iraq. These estimates suggest a global cost to date of about $428 billion. The avoided costs, meanwhile, are about$116 billion. We estimate that the expected total net present value of the direct costs through 2015 could be $604 billion to the U.S.,$95 billion to coalition partners, and $306 billion to Iraq, suggesting a global total expected net present value of about$1 trillion. The net present value of total avoided costs, meanwhile, could be about $429 billion.

Notranja oksidacija Cu-C in Ag-C kompozitov

The internal oxidation in copper-carbon and silver-carbon composites occurs when they are exposed to air or oxygen at high temperature. Solubility of carbon in copper or in silver is very low. The kinetics of oxidation at high temperature and activation energy were determined and the mechanism of internal oxidation was analysed. The kinetics of internal oxidation was determined for both cases and it is depended from the diffusion of oxygen following parabolic time dependence according to Wagner\u27s theory. The activation energy for Cu-C composite is 70.5 kJ/mol, and for Ag-C composite is 50.1 kJ/mol, what is in both cases close to the activation energy for the volume diffusion of oxygen in copper or in silver. In both cases gas products are formed during the internal oxidation of composites. In the internal oxidation zone pores, bubbles occur. The carbon oxidates directly with the oxygen from solid solution as long there is a contact, which breaks down with the presence of gas products. Then the oxidation occurs over the gas mixture of CO and CO2.Pri visokih temperaturah kompoziti bakra in srebra z ogljikom na zraku ali v kisiku reagirajo po mehanizmu notranje oksidacije. Topnost ogljika v trdnem bakru in trdnem srebru je zelo majhna. Analizirali smo kinetiko oksidacije kompozitov, določili aktivacijsko energijo in mehanizem notranje oksidacije. Kinetika oksidacije je pri obeh skupinah materialov odvisna od difuzije kisika in sledi parabolični odvisnosti od časa v skladu z Wagnerjevo teorijo. Aktivacijska energija procesa je za kompozit Cu-C enaka 70,5 kJ/mol, za kompozit Ag-C pa 50,1 kJ/mol, kar je blizu aktivacijski energiji za volumsko difuzijo kisika v trdnem bakru oziroma srebru. Pri oksidaciji kompozita nastajajo plinski produkti. Oksidacija ogljika poteka neposredno s kisikom iz trdne raztopine, ko pa se zaradi nastanka plinske faze stik prekine, pa preko plinske zmesi CO in CO2

Zona utjecaja topline kod navarivanja kromovog ledeburitnog čelika

Tools get failured during work; wear is a major factor that contributes to failures. Damaged tools are replaced or filed. This paper describes typical changes that occur in the heat affected zone of tool (HAZ), which was repaired by surfacing with a TIG and with micro-plasma procedure. Microstructure of the steel on the repaired tool was analysed by an optical and scanning electron microscope. The tool was made of chromium ledeburitic steel type W.N. 1.2379 and it was repaired by surfacing steel type W.N. 1.4718. Changes in the HAZ also depend on the type of surfacing. Besides microstructural changes, dissolution of carbides, especially primary carbides. This way the concentration of the carbide-forming elements and carbon is increased in the base around the primary carbides in the HAZ so the result is so-called secondary eutectic or secondary ledeburite.Alat se tijekom rada oštećuje. Većina oštećenja nastaje zbog habanja materiala. Oštećeni alat se popravlja navarivanjem. U ovom radu opisuju se značajne promjene u zoni utjecaja topline (ZUT) alata koji je obnovljen navarivanjem TIG postupkom i mikroplazmom. Mikrostrukturu čelika obnovljenog alata analiziralo se pomoću optičkog i scaning elektronskog mikroskopa. Alati su izrađeni iz kromovog ledeburitnog čelika W.N.1.2379, a obnovljeni su navarivanjem čelika W.N.1.4718. Promjene u zoni utjecaja topline povezane su također i s načinom navarivanja, među mikrostrukturnim promjenama specifično je rastapanje karbida, posebno primarnih. Na takav se način u okolini karbida u ZUT povećava koncentracija karbidotvornih elemenata i ugljika toliko, da dolazi do lokalnog taljenja i nastanka t.z. sekundarnog ledeburita

Has private participation in water and sewerage improved coverage? - empirical evidence from Latin America

Introducing private sector participation (PSP) into the water and sewerage sectors in developing countries is difficult and controversial. Empirical studies on its effects are scant and generally inconclusive. Case studies tend to find improvements in the sector following privatization, but they suffer from selection bias, and it is difficult to generalize from their results. To explore empirically the effects of PSP on coverage, we assemble a new dataset of connections to water and sewerage services at the city, and province level, based on household surveys in Argentina, Bolivia, and Brazil. The household surveys, conducted over a number of years, allow us to compile data, before and after the introduction of PSP, as well as from similar (control) regions that never privatized at all. Our analysis reveals that, in general, connection rates to piped water and sewerage, improved following the introduction of PSP, consistent with the case study literature. We also find, however, that connection rates similarly improved in the control regions, suggesting that PSP, per se, may not have been responsible for those improvements. On the other hand, connection rates for the poorest households also tended to increase in the regions with PSP, and in the control regions, suggesting that-in terms of connections at least-PSP did not harm the poor.Environmental Economics&Policies,Decentralization,Health Economics&Finance,Water Conservation,Water and Industry,Town Water Supply and Sanitation,Health Economics&Finance,Environmental Economics&Policies,Water Supply and Sanitation Governance and Institutions,Water and Industry