996 research outputs found
IMPORT PRICES AND HARD CURRENCY CONSTRAINTS IN EASTERN EUROPE: IMPLICATIONS FOR COARSE GRAIN IMPORTS AND PRODUCTION OF MEAT
The objectives of this study were (a) to determine the degree to which hard currency earnings constrained overall imports and coarse grain imports in command economies; (b) to measure the importance of import prices on grain imports and to trace the link of grain availability to meat production; and (c) to determine how economic and political reforms in the selected countries may have affected the hard currency constraint, the importance of import prices, and grain imports and meat production. The results indicate that import demand was constrained by earnings of hard currency, but was not responsive to world prices, and meat production was affected by total grain availability, including imports.Coarse grain imports, Hard currency, Eastern Europe, Import prices, Meat production, Political reforms, International Relations/Trade,
Research of the scope of testing required for qualification of the hvac system
In the pharmaceutical industry, HVAC system qualification is carried out by applying a risk management model in accordance to relevant GMP requirements.Qualification of these systems is an integral part of quality assurance and represents a systemic approach of data collection and data analysis that will provide documentary evidence that the system works properly and continuously gives the expected results.GMP requires identifying the extent of the qualification required to ensure reliability and compliance with GMP principles based on the outcome of the risk assessment.This paper provides an example of risk assessment approach using the FMEA method.Potential risks were identified, it was estimated which risks were considered acceptable, and risk reduction actions were proposed, from their impact on the HVAC system
Research of the scope of testing required for qualification of the hvac system
In the pharmaceutical industry, HVAC system qualification is carried out by applying a risk management model in accordance to relevant GMP requirements.Qualification of these systems is an integral part of quality assurance and represents a systemic approach of data collection and data analysis that will provide documentary evidence that the system works properly and continuously gives the expected results.GMP requires identifying the extent of the qualification required to ensure reliability and compliance with GMP principles based on the outcome of the risk assessment.This paper provides an example of risk assessment approach using the FMEA method.Potential risks were identified, it was estimated which risks were considered acceptable, and risk reduction actions were proposed, from their impact on the HVAC system
Comparative thermal buckling analysis of functionally graded plate
A thermal buckling analysis of functionally graded thick rectangular plates according to von Karman non-linear theory is presented. The material properties of the functionally graded plate, except for the Poisson's ratio, were assumed to be graded in the thickness direction, according to a power-law distribution, in terms of the volume fractions of the metal and ceramic constituents. Formulations of equilibrium and stability equations are derived using the high order shear deformation theory based on different types of shape functions. Analytical method for determination of the critical buckling temperature for uniform increase of temperature, linear and non-linear change of temperature across thickness of a plate is developed. Numerical results were obtained in MATLAB software using combinations of symbolic and numeric values. The paper presents comparative results of critical buckling temperature for different types of shape functions. The accuracy of the formulation presented is verified by comparing to results available from the literature
Inferior Mesenteric Artery Aneurysm: Case Report and Review of the Literature
Aneurysms of the inferior mesenteric artery are very rare. We report a new case associated with aorto-iliac occlusive disease and occlusion of the superior mesenteric artery, as well as review the pertinent literature
Lp stability of networked control systems implemented on WirelessHART
International audienceThis paper provides results on input-output Lp stability of networked control systems (NCSs) implemented over WirelessHART (WH). WH is a communication protocol widely used in process instrumentation. It is mainly characterised by its multi-hop structure, slotted communication cycles, and the possibility to simultaneously transmit over different frequencies. We propose a non-linear hybrid model of WH-NCSs that is able to capture these network functionalities, and that it is more general than existing models in the literature. Particularly, the multi-hop nature of the network is translated into an interesting mathematical structure in our model. We then follow the emulation approach to stabilise the NCS. We first assume that we know a stabilising controller for the plant without the network. We subsequently show that, under reasonable assumptions on the scheduling protocol, stability is preserved when the controller is implemented over the network with sufficiently frequent data transmission. Specifically, we provide bounds on the maximum allowable transmission interval (MATI) under which all protocols that satisfy the property of being persistently exciting (PE) lead to Lp stable WH-NCSs. These bounds exploit the mathematical structure of our WH-NCS model, improving the existing bounds in the literature. Additionally, we explain how to schedule transmissions over the hops to satisfy the PE property. In particular, we show how simultaneous transmissions over different frequency channels can be exploited to further enlarge the MATI bound
Nanostructured relief to orient liquid crystals materials
Electrooptical nematic liquid crystal (LC) cells, which can be used as laser switching devices, electrically and optically addressed spatial light modulators, and analogs of display elements, mostly operate in S and T configurations, which realize a planar orientation of the LC mesophase on the aligning substrate surface. However, the solution of some problems, where the initial black field is necessary for the regime of light transmission through the cell structure, requires a homeotropic alignment of LC molecules on the substrate. In the present paper the possibility of obtaining homeotropic orientation in thin film nematic liquid crystal cells using carbon nanotubes is considered. The results of this investigation can be used to develop optical elements for displays with vertical orientations of NLC molecules (MVA-display technology)
Shear strength testing of hardfaced samples using special tool on an universal testing machine
Complex working conditions of forging dies are the most frequent causes of their damage, requiring suitable hard facing repair procedures. The method of determining the bond strength between the hardfaced layer and the base material is explained in details, and the relation between hardfaced layer output results and the applied technology is established. Shear testing of materials has proven to be one of the most difficult areas of mechanical property testing. Shear modulus measurements are mainly accurate, but it is very difficult to measure shear strength. Edges, material coupling, non-pure shear loading, non-linear behaviour, imperfect stress distribution and coupling with normal stresses make shear strength determination difficult. None of the available test methods are without inaccuracies. Therefore, in structural applications, shear strength data should be used very carefully, on a case-by-case basis, appreciating the consequences of potential inaccuracies of the used values
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