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Eleftherios Makedonas, Sotirios Bellos and Subasat Turan

of mining sector investment in Ghana: a study of the Tarkwa mining region’, Draft report for SAPRI. Akinbobola T O and Saibu M O (2004) ‘Income inequality, unemployment, and poverty in Nigeria: a vector autoregressive approach’, The Journal of Policy Reform, 7, 175–183. Alexander S S (1952) ‘Effects of a Devaluation on a Trade Balance’, Staff Papers - International Monetary Fund , 2, 263–278. Ames B, Brown W, Devarajan S and Izquierdo A (2001),‘Macroeconomic policy and poverty reduction’, International Monetary Fund Draft for Comments

Open access

Vestnik Zoologii

The Journal of National Academy of Sciences of Ukraine, Schmalhauzen Institute of Zoology

Open access

Yewen Xu, Guozhu Shen, Hongyan Wu, Bin Liu, Xumin Fang, Ding Zhang and Jun Zhu

/PANI composite. To the best of our knowledge, reports on double-layer microwave absorbing materials based on the PANI and spinel ferrite materials are still very limited. In this work, spinel cobalt ferrite CoFe 2 O 4 nanocrystals were synthesized by co-precipitation method, and the CoFe 2 O 4 /PANI multi-core/shell composites were prepared by chemical oxidative polymerization of aniline. Double-layer microwave absorbers based on the calcined CoFe 2 O 4 and CoFe 2 O 4 /PANI multi-core/shell composites were designed to achieve higher microwave absorption. 2

Open access

M.V.S. Murali Krishna, N. Durga Prasada Rao, B. Anjeneya Prasad and P.V.K. Murthy

study of energy balance in low heat rejection diesel engine. Energy, 2006, 31(2-3), 364-371. [18] Parlak A., Yasar H., Eldogan O.: The effect of thermal barrier coating on a turbocharged Diesel engine performance and exergy potential of the exhaust gas. Energy Conversion and Management, 2005, 46(3), 489-499. [19] Ekrem B., Tahsin E., Muhammet C.: Effects of thermal barrier coating on gas emissions and performance of a LHR engine with different injection timings and valve adjustments. Journal of Energy Conversion and Management, 2006, 47

Open access

J. Konstanty and A. Romanski

Abstract

Why cobalt outperforms other matrix materials in its capacity for diamond retention in cutting tools is considered. To this end diamond loading conditions were modelled to establish the magnitude of stress and strain in the matrix surrounding a working diamond crystal. Only at 315 N did the contact force in Co result in plastic strain of 4-8%, which has a destructive influence on diamond retention. The strain field generated in a poorly performing Cu-40%Co-6%Sn matrix under a load of 190 N closely resembled that generated by 315 N in Co. It is postulated that diamond retention is related to the yield strength and work hardening characteristics of the metallic matrix.

Open access

M. Krishna, N. Janardhan, P. Murthy, P. Ushasri and Naga Sarada

A Comparative Study of the Performance of a Low Heat Rejection Engine with Three Different Levels of Insulation with Vegetable Oil Operation

Investigations were carried out to evaluate the performance of a low heat rejection (LHR) diesel engine consisting of different versions, such as ceramic coated cylinder head engine-LHR-1-Air gap insulated piston and air gap insulated liner-LHR-2- and Ceramic coated cylinder head, air gap insulated piston and air gap insulated liner -LHR-3 with degrees of insulation with normal temperature condition of linseed oil with varied injection pressure. Performance parameters were determined at various magnitudes of brake mean effective pressure. Pollution levels of smoke and oxides of nitrogen (NOx) were recorded at the peak load operation of the engine. Combustion characteristics of the engine were measured with TDC (top dead centre) encoder, pressure transducer, console and special pressure-crank angle software package. Conventional engine (CE) showed deteriorated performance, while LHR engine showed improved performance at recommended injection timing of 27°bTDC and recommend injection pressure of 190 bar with vegetable oil operation, when compared with CE with pure diesel operation. Peak brake thermal efficiency increased by 14%, smoke levels decreased by 10% and NOx levels increased by 30% with LHR engine at an injection pressure of 270 bar when compared with pure diesel operation on CE at manufacturer's recommended injection timing.

Open access

M. Reben, J. Wasylak and J. Jaglarz

optical fibers", Bull. Pol. Ac.: Tech. 56 (2), 103-112 (2008). T. Kosuge, Y. Benino, V. Dimitrov, R. Sato, and T. Komatsu, "Thermal stability and heat capacity changes at the glass transition in K 2 O-WO 3 -TeO 2 glasses", J. Non-CFigt. Solids 242, 154-164 (1998). D. W. Hall, M. A. Newhouse, N. F. Borrelli, W. H. Dumbaugh, and D. L. Weidman, "Nonlinear optical suscettilibilities of some Ge-Se-Te glasses", J. Non-Cryst. Solids 103, 179-194 (1988). E. M. Vogel, M. J. Weber, and D. M. Krol

Open access

Ł. Kaczmarek, M. Steglinski, J. Sawicki, J. Swiniarski, D. Batory, K. Kyzioł, Ł. Kołodziejczyk, W. Szymanski, P. Zawadzki and D. Kottfer

This paper describes two stages of optimization of the properties of 2024 and 7075 aluminium alloys, in particular their resistance to pitting by first T6, T6I6 or T6I4 treatment, and second increase its tribological properties by depositing by RF PACVD method a gradient coating of high adhesion to the substrate.

Quantitative microstructural characteristics reveals that it is possible to increase hardness (up to 190HV for 7075 alloy) with relatively high yield strength (520 MPa) and high ultimate elongation (about 20%) by optimizing dispersion of precipitates using two-stage artificial aging process.

Next to eliminate forming of thin Al2O3 layer with relatively poor adhesion to the aluminium substrate, gradient a-C: H/Ti layers synthesis hybrid plasma chemical RF PACVD reactor equipped with pulsed magnetron sputtering system was used. Using such configuration enables forming a thick and highly adherent diamond-like carbon layer on aluminium surface with low coefficient of friction (0.05), at a substrate temperature below 470K. Due to application of Ti magnetron cathode it was possible to improve the adhesion strength up to 30mN of diamond-like carbon layer to the covered substrate. Influence of deposition parameters on microhardness profile as well as adhesion and morphology were determined by nanotest and AFM, respectively.