Search results

This paper describes the changing of high‐temperature oxidation resistance (HTOR) at the temperature 1,200°C which is dependant on characteristics of alloying and microstructure. The aim of the research was to show a broad problem of using the intermetallic Ni₃Al in the production of propulsion aircraft engines because this material has a very high HTOR and low density.

For the estimation of a level of HTOR of Ni₃Al (Ni‐12Al) and its alloying compositions, a method was used in which samples were heated in ambient atmosphere at 1,200°C for a period of 1,500 h. The samples were weighed every 100 h. The data was obtained for eight different compositions.

The process of researching indicated that a maximum HTOR has the composition Ni‐12Al without alloying which is obtaining by dosed directional solidification (DDS) method and having the largest structural stability at 1,200°C.

This material is broadly used in the production of valves, electrical heaters, etc. However, these details are obtained by equiaxial casting or powder metallurgy methods. The material obtained by DDS method has higher strength characteristics and may be implicated in many components of aircraft engines (elements of the firing chamber or a stationary blades, etc.).

This research presents a new type of microstructure which has a matrix Ni₃Al on a base of disordered gamma phase (DDS Method). Currently, this structure has had little studies carried out on it. However, it could become an object for detailed research for process phase precipitation using a super high magnifications.

Presents data which relate to the problem of creating a new technique and technology. In the 1990s the problem of the practical use of intermetallids Ni₃Al and Fe₃Al as structural components in aircraft industry in the USSR was at the stage of a pilot application. In the USSR the process of the directional solidification of superalloys used in components of aircraft engines was at a high level. There was a commercial process for obtaining turbine blades with columnar structure (DC) and single crystal structure (SC) using different methods of cooling for the ingots during the growth, such as cooling on the copper shield and in melt metals (Sn,Al). On the basis of obtained data, theoretical research was conducted regarding the creation of new processes which could give rise to the possibility of directional solidification. One of these processes is the method of dosed feeding of the growing ingots. This method allows alterations to the microstructure, the plasticity, the strength of Ni₃Al and Fe₃Al intermetallids, and corrosion and oxidation resistance.

Due to the special service environment of superalloys, this paper aims to obtain effects of temperature and Ti addition on high temperature oxidation behavior of Co-Al-W-B alloys.

Isothermal oxidation experiment of Co-Al-W-based alloys were carried out at 800°C, 900°C and 1000°C for different times (3, 5, 10, 20, 50 and 100 h) referring to the method of HB5258-2000. Oxidation weight gain curves and oxidation products were detected.

The results showed that the average oxidation rates of Co-Al-W-B alloy at 800 °C and 900 °C were 0.489 g·m⁻²·h⁻¹ and 0.888 g·m⁻²·h⁻¹, respectively, which belonged to an antioxidant grade. However, the average oxidation rate at 1000 °C was 2.068 g m⁻²·h⁻¹, belonging to the secondary oxidation resistance class. In the alloy with Ti addition, dense Ti oxides film were formed at the early oxidation stage and then gradually diffused later, which can increase the oxidation resistance of the alloys to some extent. By analyzing the oxidation products of Co-Al-W-B alloy, it was found that a dense Al₂O₃ layer could be formed when the alloy was oxidized at 800°C. The continuous Al₂O₃ layer would prevent the oxygen from further spreading and make the alloy into the stable oxidation stage. However, only a non-dense Al₂O₃ layer were observed with 900°C oxidation.

It can provide references for the composition design, preparation process optimization and protective coating selection of the γ′ phase strengthened cobalt-base superalloys.

This paper aims to explore the relevant literature available regarding the use of repetitive transcranial magnetic stimulation (rTMS) as a mode of treatment for obsessive-compulsive disorder (OCD); to evaluate the evidence to support the use of rTMS as a treatment option for OCD.

The authors electronically conducted data search in five research databases (MEDLINE, CINAHL, Psych INFO, SCOPUS and EMBASE) using all identified keywords and index terms across all the databases to identify empirical studies and randomized controlled trials. The authors included articles published with randomized control designs, which aimed at the treatment of OCD with rTMS. Only full-text published articles written in English were reviewed. Review articles on treatment for conditions other than OCD were excluded. The Covidence software was used to manage and streamline the review.

Despite the inconsistencies in the published literature, the application of rTMS over the supplementary motor area and the orbitofrontal cortex has proven to be promising in efficacy and tolerability compared with other target regions such as the prefrontal cortex for the treatment of OCD. Despite the diversity in terms of the outcomes and clinical variability of the studies under review, rTMS appears to be a promising treatment intervention for OCD.

The authors of this scoping review acknowledge several limitations. First, the search strategy considered only studies published in English and the results are up to date as the last day of the electronic data search of December 10, 2020. Though every effort was made to identify all relevant studies for the purposes of this review per the eligibility criteria, the authors still may have missed some relevant studies, especially those published in other languages.

This review brought to bare the varying literature on the application of rTMS and what is considered gaps in the knowledge in this area in an attempt to evaluate and provide information on the potential therapeutic effects of rTMS for OCD.

Automating the assembly of an existing product is not always easy, particularly if its redesign cannot be cost‐justified. Anna Kochan reports from TRW Torrix on the outskirts of Paris.

Against the background of rising mental health (MH) problems many practitioners and health programmers require tools to plan and implement mental health promotion (MHP). A Likert scale to measure Perceived Knowledge of Skills needed for MHP (PKSMHP) was developed and pilot tested. The paper aims to discuss these issues.

A convenience sample of leading personnel (n=106) in three settings (43 schools, 24 workplaces, 39 care facilities) was drawn in five European countries. A descriptive item analysis, an exploratory and confirmatory factor analysis, and a scales’ performance analysis was adopted.

The validated PKSMHP scale included nine high-quality items measuring the knowledge level of three skills dimensions: MHP management/planning, MHP tools/methods/services and recognition/detection of MH problems. Taken together these can be seen to represent the overall type of skills needed for implementing MHP.

The short scale showed very good scale performance values in this pilot study. After further testing the scale might be used as a baseline assessment of MHP needs, as a building block for MHP training and organisational capacity building.

The purpose of this paper is to study the nature of the relationship between the entrepreneur and the banker, which is central to any analysis of business creation and innovation management. The author’s main purpose is to understand how this relationship has been studied by the pioneer economists of the entrepreneur and to highlight their contribution to the understanding of today’s reality.

To do so, the author proposes a sketch of an entrepreneur and banker economics based on the study of six economists (Cantillon, Smith, Bentham, Say, Schumpeter and Baumol) known for their works on entrepreneur theory. In their works, they explained how the (often difficult) relationship between the entrepreneur and the banker is built in a context of multi-uncertainty. They define the entrepreneur in different ways (a risk-taker, a prudent man, a projector, etc.), and put forward different behaviors facing uncertainty through social relations. The relationship between the entrepreneur and the banker can be read according to the grid of analysis of strong or weak ties (Granovetter, 1973).

This analysis demonstrates the importance of trust between the two protagonists. This contribution remains fundamental to study the behavior of financers and entrepreneurs today in the context of business eco-systems, clusters, science parks ‒ in other words, the main places of emergence of innovation.

This research leads to the proposal of the main basis of an economics of the entrepreneur and the banker; it can be further developed with the addition of other contributions of historical economists.

This research shows the importance of thinking about the ways to build trust within the relation between entrepreneurs and their funders (bankers, venture capital, crowdfunding).

The analysis of social ties (weak or strong) plays a major role in this relation.

The originality of the article is to come back to the works of pioneer economists and to show their contributions to the understanding of today’s reality.

THE development of aircraft penumatic equipment has progressed so satisfactorily in recent years that actuation of vital services by means of compressed air is becoming increasingly popular. In this brief review of developments to date an attempt will be made to show how the air which has been made available as a result of compressor improvements is utilized and by way of introduction it may be of interest to recall some of the bold experiments which were made in earlier years.

In the first millennium AD when international trade brought silver coins to Madagascar, they were melted down for jewelry or cut into pieces to meet the needs of small-scale local trade. The Merina culture of the highland interior saw in the original uncut silver coin an image of completeness and perfection. Such coins became obligatory ritual offerings acknowledging the sanctity of the sovereign. “Ritual economy” is brought into fine grain relief when pieces of “all-purpose money” are used in ritual prestation and when markets become a symbol of morality indexing political legitimacy. Today traditions of the highlands have co-opted the royal offering of “uncut coins” for local ritual purposes and local ritual specialists engage in symbolic assaults on “all-purpose money.” This chapter draws upon Merina royal oral traditions, ethnohistoric accounts, and contemporary ethnographic work with Betsileo ritual specialists to argue that the poetic and the syncretic necessarily enter into discussions of the economic.