380 research outputs found
Effects of angular injection, and effervescent atomization on high-velocity suspension flame spray process
This work presents the nanostructured coating formation using suspension thermal spraying through the HVOF torch. The nanostructured coating formation requires nanosize powder particles to be injected inside a thermal spray torch using liquid feedstock. The liquid feedstock needs to be atomized when injected into the high-velocity oxygen fuel (HVOF) torch. This paper presents the effects of angular injection and effervescent atomization of the liquid feedstock on gas and droplet dynamics, vaporization rate, and secondary breakup in the high-velocity suspension flame spray (HVSFS) process. Different angular injections are tested to obtain the optimum value of the angle of injection. Moreover, effervescent atomization technique based on twin-fluid injection has been studied to increase the efficiency of the HVSFS process. Different solid nanoparticle concentrations in suspension droplets are considered. In angular injection the droplets are injected into the core of the combustion zone; this immediately evaporates the droplets, and evaporation is completed within the torch. The value of 10°â15° is selected as the optimal angle of injection to improve the gas and droplet dynamics inside the torch, and to avoid the collision with the torch's wall. The efficiency of the effervescent atomization can be enhanced by using high gas-to-liquid mass flow rate ratio, to increase the spray cone angle for injecting the suspension liquid directly into the combustion flame. It is also found that the increment in the nanoparticle concentration has no considerable effects on the droplet disintegration process. However, the location of evaporation is significantly different for homogeneous and non-homogeneous droplets
Brazil's rise and the role of big business
The heart of Brazilâs recent rise in international relations lies in its growing influence in the global economic arena. This article evaluates one aspect of economic activity â the emergence of Brazilian transnational corporations. The article argues that an important legacy of decades of state intervention in the market fostered the successful internationalisation of big business in Brazil, impacting on Brazilâs international profile. However, this legacy also hampered its systemic competitiveness as evidenced by various international competitiveness rankings. The article concludes with some remarks on the long-run sustainability of Brazilâs current economic performance
Computational modelling of thermal spraying processes
The main aim of this project is to model the effects of varied injection
parameters on the gas dynamics and droplet dynamics of the HVSFS and SP-
HVOFS processes for improving the droplet breakup and evaporation to
enhance the nanoparticles heating and deposition efficiency. Thermal spraying
processes are widely used to generate thermal-, corrosion-, and wear-resistant
layers over the machine parts, to increase the durability of the equipment under
severe environmental conditions. The liquid feedstock is used to achieve
nanostructured coatings. It is used either in the form of a suspension or a
solution precursor. The suspension is a mixture of solid nanoparticles
suspended in a liquid medium consisting, for instance, of water, ethanol, or
isopropanol. This dispersion mechanism in a liquid carrier provides adequate
flowability to the nanoparticles, which cannot be handled by conventional gas-
based feeding systems, whereas the solution precursor is mixed at the
molecular level; hence, more uniform phase composition and properties are
expected in the sprayed coatings as compared to the suspension and
conventional powder spraying.
Firstly, experiments are conducted to analyse the effects of different precursor
concentrations, solvent types and injection nozzles on the size and morphology
of synthesized nanoparticles. The results indicate that the particle size
increased with increasing precursor concentration due to the variations in the
physical properties of the mixture solution. The higher precursor concentrations
had an adverse effect on the droplet atomization and evaporation process that
led to bigger size particle formation. The use of aqueous solvent has some
limits and with higher precursor concentration the surface tension increases that
resulted in the reduction of dropletsâ disintegration, and thus bigger size
precursor droplets generate larger nanoparticles. A mixture of aqueous-organic
solvents and pure organic precursors are preferred to improve the process
efficiency of the nanoparticles size and morphology. Furthermore, the
nanoparticles size can be controlled by using liquid feedstock atomization
before injecting into the HVOF torch. A new effervescent injection nozzle is
designed and compared to different types of existing injection nozzles, to see
the variations in the droplet disintegration, and its effects on the performance of
the HVOF torch processes. It is detected that the atomization would result in
smaller size particles with homogeneous morphology. In a numerical study,
different droplet injection types are analysed to see their effects on the gas and
droplet dynamics inside the HVOF torch. The group-type injection (GTI) and
effervescent-type atomization (ETI) are used effectively to overcome the heat
losses and delays in the droplet evaporation. These approaches reduce the
thermal and kinetic energy losses in the suspension-fed-HVOF torch, thereby
improving the coating formation.
The effects of using multicomponent water-ethanol mixture injection in the
HVOF torch are also modelled, and its impact on the droplet breakup and
evaporation are studied. The organic solvents have a low heat of vaporization
and surface tension, and can effectively be used in the HVOF spraying process
over the water-based solvents. Furthermore, nanoparticles are suspended in
the liquid feedstock and injected into the HVOF torch. The effect of increasing
nanoparticlesâ concentration in the feedstock and its consequence on the gas
dynamics, droplet breakup and evaporation are analysed. The augmentation in
the nanoparticles loading in the suspension droplets can decrease the droplet
breakup and evaporation rate because the required heat of vaporization
increases significantly. Moreover, the size of injection droplet affects the droplet
fragmentation process; bigger sized droplets observed a delay in their
evaporation that resulted in coating porosity. The results suggest that smaller
droplet sizes are preferred in coating applications involving a higher
concentration of nanoparticles with high melting point.
Further, the gas flow rates (GFRs) are regulated to control the droplet
dispersion, atomization and evaporation inside the solution precursor fed-HVOF
torch. The size of the droplet diameter is decreased by an increment in the
GFR, as higher combustion rates increase the combustion flame enthalpy and
kinetic energy. Moreover, the increase in the oxygen/fuel flow rates dilutes the
injected precursor. It reduces ZrO2 concentration in the process and decreases the rate of particle collision; as a result, non-agglomerated nanoparticles can be
obtained
Women at the Workplace - The Journey of Three Generations of Women
"Women at the Workplace- The Journey of Three Generations of Women", is based on interviews conducted by the authors of a broad cross-section of women in leadership positions, middle management levels as well as women beginning their careers and those making a second start after some years of motherhood. Face to face interviews, each lasting several hours, with 32 women was the main source of information. In only 2 of these 32 cases, a questionnaire was employed. A broad framework was provided to the participants and used as a template for brainstorming. The persons early background, role models, dreams and aspirations, career achievements and the interplay between personal and professional lives was explored. The participants were asked to introspect and explore what success meant to them. A road map for the future for women in organizations was examined. The survey provided a fascinating insight into the minds and hearts of working women. Different women had different motives for working, different dreams and aspirations, different perceptions of the future, different support systems and different hurdles, however, there was also a deep rooted commonality. Looking beneath the surface many common themes and trends emerged for women with different backgrounds, different personality types and varied levels of education, seniority and experience. The human spirit wanted to achieve, to explore and to succeed - only the manifestation of this spirit was different in different cases. An equally strong parallel theme related to fulfillment beyond the realm of professional achievement was prevalent. An underlying need to fulfill maternal and societal roles was observed. The major challenge was to balance these seemingly contradictory aspirations and to achieve happiness. Paths traversed by these 32 women were different, each path equally valid for each person. However, these paths had many crossroads where each individual meets others and then continues on their own path. Till the next crossroad.
Laughter
Set in Boise, âLaughter,â is centered on a gullible anti-heroine and an aspiring writer, who is infatuated with a poet.
The novel is about relationships with parents, friends, strangers, complete strangers. An inquiry into what it means to live an authentic life; and what to make of âotherâ people in fiction: people in books, films, songs.
Itâs about blurriness: funniness and sadness; creepiness and devotedness; fiction and reality
Brazil's role in institutions of global economic governance : the WTO and G20
The article evaluates the extent to which Brazil's foreign policy actions, negotiating positions and diplomatic strategies in global governance institutions contribute to supporting its national interest and foreign policy aims. It compares Brazil's preferences and behaviour in the World Trade Organization (WTO) and Group of 20 (G20). For decades, Brazil's primary national interest has been national economic development. The article argues that Brazil is moving from a material interests based definition of its prime national interest to a more complex one that includes both material and prestige/status based aspects. Research demonstrates that Brazil has become increasingly focused on gaining recognition as a leader of developing countries, sometimes even at the cost of realising its full material interests. It considers the value of constructivist international relations theory to understanding Brazilian foreign policy
Assessing the changing roles of the Brazilian Development Bank
Since it was founded in 1952, the Banco Nacional de Desenvolvimento EconĂŽmico e Social (BNDES; Brazilian National Bank for Economic and Social Development) has been at the centre of Brazil's industrialisation and development strategy. It played a key role in the evolution of policies from import substitution to market-opening and privatisation, to the ânew developmentalismâ. The article evaluates and discusses whether BNDES fulfils the three typical functions expected of national development banks: financial sector development; business climate enhancement; and knowledge services
Brazilian business and Itamaraty in the PT era: foreign policy-making in the context of âgraduation dilemmasâ
This article discusses how Brazilian foreign policy-makers addressed one of the key graduation dilemmas facing Brazil, i.e. the need to build domestic support for a shared vision within society for Brazil's role in the international arena. In the context of democratization, foreign policy-makers understood the importance of involving societal actors in developing foreign policy agendas and actions without hampering the coherence of diplomatic activity. Furthermore, in the context of the rising profile of Brazil in regional and global affairs, it became increasingly relevant to identify and appreciate the role of domestic influences and constraints on foreign policy-making. The article argues that the years the Workers' Party (PT) was in government (2003â2016) presented a watershed moment for foreign policy-makers' receptiveness to civil society inputs into foreign-policy debates. To do this, the article analyses how one crucial group of societal actorsâbusinessâorganized to represent its interests on foreign economic policy, specifically trade policy, and how the Itamaraty (Ministry of External Relations) responded to business collective action. It examines business interactions with the Itamaraty in two phases, with the global financial crisis in 2008 roughly serving as the inflection point. It argues that the shift in the PT's foreign policy-making approach occurs due to three factors: changes in economic conditions, political leadership and societal interest representation. It concludes that the shifting policy preferences (both pragmatic and ideological) also changed the mix of societal influence on foreign policy
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