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OVER A QUARTER of a century ago, in September 1938, we published a review of diffuser behaviour by G. N. Patterson which, together with one of its main information sources by Gibson, has formed the accepted guide to diffuser design. Patterson's paper was broad in scope and made clear reference to the effect of parameters which were not fully investigated until much later. It is the purpose of this paper to review experimental work, much of it being along the lines formulated by Patterson, and to indicate the improved analytical understanding of diffusers.

A QUARTER of a century ago, in September 1938, this journal published a review of diffuser behaviour by G. N. Patterson1 which, together with one of. its main information sources by Gibson,2 has formed the accepted guide to diffuser design. Patterson's paper was broad in scope and made clear reference to the effect of parameters which were not fully investigated until much later. It is the purpose of this paper to review experimental work, much of it being along the lines formulated by Patterson, and to indicate the improved analytical understanding of diffusers.

AN interesting feature of modern aeroplane design is the growing use of duct systems. The low drag and heat regeneration obtainable from a cooling duct is now an accomplished fact. Ventilation systems for cabin aircraft have been introduced. In the future we may see duct systems used in connexion with the control of the boundary layer. As aeroplane design is improved, new applications of duct systems continue to appear.

ONE of tin: most important causes of low efficiency in duel systems is tin; large loss which accompanies a transformation from kinetic energy to pressure. The exit cones of wind tunnels and turbines and the expanding entries to cooling duets and air‐intakes on aircraft are some of the duct systems which lvcpiirc ellicient expansions of the flow.

IN 1938 a review of conical diffuser performance by Patterson (Ref. 1) was published in this journal, and a reappraisal by Cockrell and Markland (Ref. 2) was given in 1963. The two articles are widely referred to for design purposes, although other reviews have appeared more recently (by Reneau et al (Ref. 3) in 1964, and Cockrell and King (Ref. 4) in 1967). Cockrell and Markland also included some preliminary results from an investigation which they instigated at Nottingham University, and it is the continuation of this work which is the subject of this paper.

DUCT systems of various types are used on aircraft. The efficiency of the systems depends upon the losses in the duct. A corner in the duct may produce a large resistance to flow if it is not carefully designed. Research on the problem of corner resistance has been undertaken by a number of investigators. Their results show that the design of a corner is very important. In the following discussion the more significant results are summarized and some factors governing the design of an efficient corner are set forth.

The objective of this study is to examine the effect of corporate image, perceived value, and switching costs on customer loyalty in customer/provider relationships of different length.

Five key constructs, namely: corporate image, perceived value, switching costs, customer loyalty, and length of relationship, were employed. Using a systematic sampling technique, student interviewers randomly approached customers exiting hair salons. The final survey sample consisted of 279 respondents.

This paper supports a contingency model with regard to customer loyalty and its antecedents. The results suggest that corporate image impacts customer loyalty in both newer and older relationships. Whereas in newer relationships, corporate image has a cardinal influence on switching costs, in more‐established relationships switching costs are influenced primarily by perceived value. In both cases, switching costs influence customer loyalty.

As extant research claims that relationship quality, and not length, moderates the relationship between loyalty/repurchase behavior and their antecedents, future research could adopt relationship quality as a moderator to test the model of the present study.

The results support the importance of enhancing corporate image to retain newer customers. In longer‐established relationships, corporate image remains a determinant of repurchase decisions. However, customer value also has a significant influence on switching costs and loyalty.

The current study moves beyond customer‐perceived value, switching costs, and corporate image to demonstrate that relationship length has a significant influence on customer loyalty.

Accurate prediction of temperature and heat is crucial for the design of various nano/micro devices in engineering. Recently, investigation has been carried out for calculating the heat flux of gas flow using the concept of sliding friction because of the slip velocity at the surface. The purpose of this study is to exetend the concept of sliding friction for various types of nano/micro flows.

A new type of Smoluchowski temperature jump considering the viscous heat generation (sliding friction) has recently been proposed (Le and Vu, 2016b) as an alternative jump condition for the prediction of the surface gas temperature at solid interfaces for high-speed non-equilibrium gas flows. This paper investigated the proposed jump condition for the nano/microflows which has not been done earlier using four cases: 90° bend microchannel pressure-driven flow, nanochannel backward facing step with a pressure-driven flow, nanoscale flat plate and NACA 0012 micro-airfoil. The results are compared with the available direct simulation Monte Carlo results. Also, this paper has demonstrated low-speed preconditioned density-based algorithm for the rarefied gas flows. The algorithm captured even very low Mach numbers of 2.12 × 10⁻⁵.

Based on this study, this paper concludes that the effect of inclusion of sliding friction in improving the thermodynamic prediction is case-dependent. It is shown that its performance depends not only on the slip velocity at the surface but also on the mean free path of the gas molecule and the shear stress at the surface. A pressure jump condition was used along with the new temperature jump condition and it has been found to often improve the prediction of surface flow properties significantly.

This paper extends the concept of using sliding friction at the wall for micro/nano flows. The pressure jump condition was used which has been generally ignored by researchers and has been found to often improve the prediction of surface flow properties. Different flow properties have been studied at the wall apart from only temperature and heat flux, which was not done earlier.

The current work aims to analyze the role of commitment perceived by the consumer in the maintenance of long‐term relationships. The context of analysis chosen is the tourism sector, more specifically the relationships that retail travel agencies establish with their consumers. The study tests a conceptual model via a system of structural equations using the statistics package EQS 6.1 for Windows. The results corroborate the importance of the consumer’s trust in the travel agency and the consumer’s perception of the firm’s commitment, because this commitment acts as an antecedent of trust and creates the conditions for the firm to achieve a stable portfolio of customers.

This paper aims to present a survey of the perceptions of the barriers to implementing reverse logistics (RL) practices in South Australian (SA) construction organisations. Despite the extensive research on forward logistics and RL, there is a paucity of studies that examine the barriers to implementing RL particularly within the Australian construction industry. This study builds on the ongoing research being undertaken by the authors, entitled “Designing for reverse logistics (DfRL) within the building life cycle: practices, drivers and barriers”, which is examining the best practices and drivers that could be used as a “road map” for developing appropriate solutions for the successful implementation of RL.

Data were collected by utilising a triangulated data collection approach, a literature review and 49 questionnaires. The review of the literature identified 16 barriers to implementing RL. The quantitative survey data were subjected to descriptive and inferential statistics with correlation analysis to examine the relationships between different pairs of variables comprising RL’s critical barriers.

The following barriers were indicated as most significant: lack of incorporation of salvaged materials by designers; regulation restrictions to usage of recovered materials and components; potential legal liabilities; higher costs; and longer-time association with deconstructing buildings. The least ranked barriers were mostly drawn from the operational and industrial categories as being: organisational lack of support for deconstruction due to incompatible design; lack of organisational support for deconstructing buildings due to higher health and safety risks; and inadequate skills and experience for deconstruction (operational). The industrial barrier was related to “higher costs of salvaged materials in comparison to virgin products”.

First, the reported findings are focussed on one study that used questionnaire surveys within the construction industry; therefore, the results may not be generalisable to other contexts. Further, studies should be conducted and extended to other industrial sectors beyond the construction industry. Second, the quantitative study (n = 49) used a smaller sample, and the survey items were based on the review of the literature.

The identified barriers could be used as a “road map” for the development of appropriate solutions for the successful implementation of RL, and to improve the environment-related decision-making processes of contractors.

This study makes a contribution to the body of knowledge on the subject of RL within a previously unexplored SA context. In addition, the study provides some insights on the contributory effects of the barriers to the implementation of RL. It is the first work undertaken to determine the barriers to the adoption of RL within the SA construction industry.