The Race to Regional Hegemony: A Case Study of the Iran-Saudi Rivalry in Yemen

The main goal for this thesis is to review how the Islamic Republic of Iran and the Kingdom of Saudi Arabia’s actions in Yemen’s civil war can be explained through the international relations theory Classical Realism. Studying Iran and Saudi Arabia’s rivalry is important for academic study because it creates an imbalance of power in the Middle East and intensifies security issues in the region. Both Iran and Saudi Arabia hold the most influential economic and political systems in the Middle East, presenting a dilemma for power and security between the two. There most recent example of this rivalry can be seen through their engagement in the Yemeni civil war. By invading the state sovereignty of Yemen to conduct a proxy war, Iran and Saudi Arabia have exemplified their desire to obtain regional hegemony. In this paper, I will utilize the zero-sum game and security dilemma, to explain Iran and Saudi Arabia’s motivations and participation in the Yemeni civil war. Furthermore, I will argue that Iran and Saudi Arabia are utilizing Yemen to obtain geostrategic power in their race towards regional hegemony

Corrosion behaviour of brazed multilayer material AA4343/AA3003/AA4343: Influence of coolant parameters

This paper is the second part of a work devoted to corrosion in brazed AA4343/AA3003/AA4343 materials on the water side of automotive heater cores. In the first part of the study [S. Tierce, N.Pébère, C. Blanc, C. Casenave, G. Mankowski, H. Robidou, Electrochim. Acta 52 (2006) 1092], corrosion initiation in the surface layer (i.e. the residual cladding) has been investigated. It has been associated to defective sites in the passive film covering the alloy. The defective sites are linked to a-Al(Mn,Fe)Si particles built up during brazing process. Interactions between a-Al(Mn,Fe)Si particles and the matrix are responsible for the observed behaviour. The present study focuses on the propagation of corrosion through the material in neutral water–ethylene glycol mixtures with and without chlorides. Comparison of the electrochemical behaviour of the three layers of the brazed material (i.e. the residual cladding, the "band of dense precipitates (BDP)" and the core material) revealed that the residual cladding was nobler than the BDP and the core material and thus that the corrosion should propagate through the inner layers due to galvanic coupling: the inner layers constitute the anode and the residual cladding the cathode. Increasing the ethylene glycol content in the water–ethylene glycol mixture decreased the rate of consumption of the materials whereas addition of chloride ions increased it. Mass variation measurements of brazed material in different solutions containing the degradation products of ethylene glycol showed that only glycolate ions had a slight detrimental effect. Corrosion tests performed in heater core tubes allowed the propagation mechanisms to be confirmed

Corrosion behaviour of brazing material AA4343

This paper is part of a work devoted to corrosion of brazed AA4343/AA3003/AA4343 materials on water side of automotive heater cores. The microstructure of the superficial resolidified AA4343 brazing material has been previously characterised [1] and [2]. It is composed of large (Al) grains separated by valleys containing multiphase deposits of (Al), Si and α-Al(Mn,Fe)Si. The present study focuses on its electrochemical behaviours in neutral water–ethylene glycol mixtures at different temperatures with and without chloride ions. Three types of behaviour are revealed: (i) passivation, (ii) defective passivation and (iii) pitting corrosion at the corrosion potential. The defective passivation is investigated in greater depth. The results show that Si needles do not participate in the corrosion progress whereas the α-Al(Mn,Fe)Si particles are preferential sites for corrosion attacks. α-Al(Mn,Fe)Si particle/matrix interactions are responsible of the defective passivation at valleys level where the α-Al(Mn,Fe)Si phase particles are mainly concentrated. Increasing the temperature enhances this reactivity whereas addition of ethylene glycol decreases it and favours a transition from defective passivation to passivation for ethylene glycol content higher than 55%

Study of the microstructure resulting from brazed aluminium materials used in heat exchangers

Re-solidification of AA4343 cladding after brazing as well as the related precipitation in the modified AA3003 core material have been investigated. Analysis of the re-solidified material showed that partial dissolution of the core alloy occurs in both the brazing joints and away of them. Far from the brazing joints, the dissolution is, however, limited and diffusion of silicon from the liquid into the core material leads to solid-state precipitation in the so-called “band of dense precipitates” (BDP). On the contrary, the dissolution is enhanced in the brazing joint to such an extent that no BDP could be observed. The intermetallic phases present in the resolidified areas as well as in the core material have been analyzed and found to be mainly cubic alpha-Al(Mn,Fe)Si. These results were then compared to predictions made with available phase diagram information

Effects of Reserpine on Artificially Inseminated Turkeys and Semen Metabolism

Poultry Scienc

Etude de la corrosion des alliages d'aluminium brasés constituant les échangeurs thermiques utilisés dans les véhicules automobiles

La représentativité des tests de corrosion est un sujet récurrent dans les études de durabilité des matériaux. Le travail s’est intéressé aux alliages d’aluminium brasés AA4343/AA3003 /AA4343 utilisés pour la fabrication des échangeurs thermiques automobiles. Leur structure métallurgique et leurs mécanismes de dégradation en corrosion ont été étudiés. L’étape d’initiation dans le placage resolidifié a été associée à des interactions entre les particules de phase ®¡Al(Mn; Fe)Si et l’aluminium. Un couplage galvanique entre la couche noble que constitue le placage résiduel et le matériau de cœur induit ensuite une propagation caverneuse. L’influence de la composition de l’électrolyte et de la température a été évaluée. L’utilisation d’un antigel dégradé synthétique à pH neutre, contenant 10 % d’éthylène glycol, des chlorures (354 ppm) et des glycolates (500 ppm) permet d’obtenir des faciès de corrosion comparables à ceux générés en service. ABSTRACT : The representativity of corrosion testing is a recurrent topic in studies of material durability. This work was devoted to brazed aluminium alloys AA4343/AA3003/AA4343 used for automotive heat exchangers. The metallurgical structure and the mechanisms of corrosion degradation were investigated. The initiation of the corrosion in the resolidified cladding was associated to ®¡Al(Mn; Fe)Si phase particles / (Al) matrix interactions. Then, a galvanic coupling between the noble layer constituted by the residual cladding and the core material was found to induce cavernous propagation of the corrosion. The influence of electrolyte composition and temperature was investigated. The use of a synthetic degraded coolant at neutral pH, containing 10 percent ethylene glycol, chloride (354 ppm) and glycolate (500 ppm) allows corrosion features comparable to those generated in service to be obtained

Low voltage plasma jet with piezoelectric generator : preliminary evaluation of decontamination capabilities

This paper deals with the proof of concept and the preliminary evaluation of decontamination performances obtained with a plasma jet generated by a piezoelectric transformer. This low voltage supply solution (<10V) is investigated as a plasma jet device, compact and safe solution for the decontamination of medical thermo-sensitive devices. The principle of the piezoelectric generator is presented, followed by the optical spectroscopy of the plasma jet, the protocol conditions for the bactericidal effect observations and finally the reduction rates obtained on Pseudomonas aeruginosa and Staphylococcus aureus bacteria strains with an argon plasma jet at atmospheric pressure about 2.5W electrical input power