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1 – 10 of 979M. Nowotarski and R. De Wilde **
The effects of oxygen on solder surface tension, wetting time and surface damping are presented. Oxygen levels greater than 10 ppm lower surfacetension, increase wetting time and…
Abstract
The effects of oxygen on solder surface tension, wetting time and surface damping are presented. Oxygen levels greater than 10 ppm lower surface tension, increase wetting time and increase surface damping. Decreased surface tension leads to higher misalignment defects in reflow soldering, but can lower the incidence of dewetting. Increased wetting times can increase non‐wetting defects in both wave and reflow soldering, especially when using no‐clean fluxes. Increased surface damping can lead to lower bridging rates in wave soldering, provided that the oxygen level and flux levels are properly balanced. Choosing the optimum oxygen level for production soldering is trade ‐ off between the stability and the versatility of the process. The most stable soldering processes will be those performed in an inert atmosphere with less than 10 ppm oxygen .These processes are insensitive to variations in soldering machine operating parameters (i,e. a larger process window).This is most desirable for manufacturers soldering large volumes of a given circuit board. The soldering process can be optimised by optimising the circuit board design. The most versatile soldering processes will be those performed in an inert atmosphere with controlled addition of oxygen in the range of 100 ppm to 10,000 ppm (1%). This will be most desirable to manufacturers soldering short runs of a large variety of circuit boards. The soldering process is best optimised by controlling the soldering machine operating parameters (oxygen, flux, preheat, conveyor speed, etc.).
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Ryan Peterson and Robin B. DiPietro
Drawing on theories of development economics and sustainable tourism, this research explores the differences between sovereign and nonsovereign small island tourism economies…
Abstract
Purpose
Drawing on theories of development economics and sustainable tourism, this research explores the differences between sovereign and nonsovereign small island tourism economies (SITEs) and identifies the antecedents and effects of overtourism in the Caribbean.
Design/methodology/approach
The research design is based on a comparative case study of selected Caribbean SITEs. Case study research involves a detailed empirical inquiry that investigates a contemporary phenomenon within its real-life context. The main purpose of a case study is to provide a contextual analysis of the conditions and processes involved in the phenomenon under study. A comparative case study is an appropriate research methodology to explore new multi-faceted concepts with limited empirical evidence.
Findings
The results confirm previous studies that nonsovereign SITEs have a distinctive overdrive toward tourism specialization. Moreover, the findings indicate that overtourism is driven by both global and domestic policy factors and generates significant economic volatility, social inequality and ecological stress. The paper discusses the tourism policy implications of the evolving economic disconnectedness, environmental decay and social tensions in SITEs in the Caribbean.
Originality/value
Policy recommendations are presented for transitioning toward a more inclusive development and strengthening the resilience of small island tourism development in the Caribbean.
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FLIGHT experience during recent years with roller strip maps driven from Doppler groundspeed data in an ‘along’ and ‘across’ track mode has demonstrated many of the undoubted…
Abstract
FLIGHT experience during recent years with roller strip maps driven from Doppler groundspeed data in an ‘along’ and ‘across’ track mode has demonstrated many of the undoubted advantages of a pictorial display of ground position.
‘The enlarged Community cannot afford a gentle period of gradually growing together.’
Yongrong Wang and Peihua Zhang
This study aims to clarify the key factors among physical‐mechanical properties of fabrics in relation to the dynamic pressure performance of compression garment.
Abstract
Purpose
This study aims to clarify the key factors among physical‐mechanical properties of fabrics in relation to the dynamic pressure performance of compression garment.
Design/methodology/approach
The physical‐mechanical properties of 16 different fabrics were measured using a KESF standard evaluation system and INSTRON tensile tester, and the garment pressure was measured by dynamic pressure measuring system. Grey correlation analysis is used to determine the correlation degree of fabric physical‐mechanical properties and dynamic pressure magnitude.
Findings
The mechanical behaviors (e.g. tensile, shearing, and bending) and physical characteristics are different in elastic fabrics with varied content of elastic fiber, kinds of yarn, et al. Grey correlation analysis is a valid method to analyze the indices of a system, quantize them and put them in order. All the degrees of Grey correlation are more than 0.6. The degree of grey correlation between tensile force (F), shearing rigidity (G) and bending rigidity (B) are higher than others, hence it is conducted that these would significantly effect on garment pressure. The quantitative regression equations between pressure magnitude at extension of 50 percent and the individual key parameters (mean values in wale and course directions) of tested samples are illustrated.
Research limitations/implications
The other parameters (e.g. fabric structure, yarn fineness, and pre‐tension, et al.) should be taken into account. Further, an integrative mathematic model would be established, which could predict the garment pressure directly from the physical‐mechanical properties of fabric.
Originality/value
The present study indicates that pressure magnitude of elastic fabric is an integrative action performed by physical‐mechanical properties. The developed illustrative equations and method offer a rational and practical tool for assessing pressure functional performance of elastic fabric in the stages of design and product development.
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Houda Barhoumi, Saber Marzougui and Saber Ben Abdessalem
The conception of a compression garment that applies a desired interface pressure level has been a great challenge for therapists and compression garment manufacturers even today…
Abstract
Purpose
The conception of a compression garment that applies a desired interface pressure level has been a great challenge for therapists and compression garment manufacturers even today. The purpose of this study is to develop a new method for designing a compression legging that exerts Class I interface pressure to the lower limb.
Design/methodology/approach
This research presents a new method for the design of Class I compression garment. It consists of theoretically calculating the circumferences of the Class I compression legging based on the reduction factors. To assess the effectiveness of the method, we used both objective and subjective evaluations. For the objective evaluation, we have developed a measuring device to measure Class I legging interface pressure in different measuring points using a force pressure sensor. Concerning the subjective evaluation, 10 healthy female subjects agreed to take part in this study in order to evaluate the ergonomic comfort when wearing the designed compression legging.
Findings
Participating subjects delivered their feeling about comfort and motion restriction during the use of the legging. Referring to the volunteers’ answers, the Class I compression legging can be described as comfortable and has a satisfactory fit during wear.
Originality/value
The important feature of this study was the effectiveness of the new designing method in producing a compression legging that delivers the desired amount of pressure and offers a comfort sensation during wear. The outcome of this research is a new method that could be used to create a variety of compression garments that can apply different pressure levels.
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DESPITE the quite extensive literature on foam, the mechanism of its formation and decay does not appear to be widely appreciated. Most fundamental research has been orientated…
Abstract
DESPITE the quite extensive literature on foam, the mechanism of its formation and decay does not appear to be widely appreciated. Most fundamental research has been orientated towards maximum foam in aqueous solutions, whereas the desire in aircraft engines is for minimum foam in oil ‘solutions’. Further, the numerical results obtained experimentally depend on the details of experimental procedure, which makes correlation of existing data very uncertain.
It was typical in nineteenth century economic thought to view thetensions between the interests of capital and labour as critical toindustrial society. Yet later economic thought…
Abstract
It was typical in nineteenth century economic thought to view the tensions between the interests of capital and labour as critical to industrial society. Yet later economic thought has generally reduced these tensions to those captured in contract theory. Explores how this narrowing of focus has cast an important source of contemporary social dynamics into the shadows. A broad survey is made of the various ways in which capital‐labour tensions are manifested in today′s advanced industrial economies, with special attention given to the case of the USA. Concludes with a discussion of how intensified international competitiveness, combined with our increasing distance from the threat of material privation, may force societies to restructure their economies so as to eliminate the source of capital‐labour tensions. The task facing liberal economic thought is to expand its scope to better provide guidance for meeting this challenge.
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Shoujun Yin, Fangmei Lu, Yong Yang and Runtian Jing
The purpose of this paper is to provide an imprinting perspective of the organizational culture evolution at a large state-owned heavy equipment manufacturer. It aims at exploring…
Abstract
Purpose
The purpose of this paper is to provide an imprinting perspective of the organizational culture evolution at a large state-owned heavy equipment manufacturer. It aims at exploring sensitive periods and the tension between persistence and decay of imprints.
Design/methodology/approach
It employs the case study approach. Both qualitative (interviews) and quantitative (survey) data were collected, from the directors, middle managements, and grass-roots staffs of Dong Fang Turbine Co. Ltd. Based on the set of four scenarios, both within-scenario analysis and cross-scenario analysis were conducted following the “replication logic.”
Findings
New survival threats are more possible to develop sensitive periods with new imprints than transition periods, and the authors suggest organizational culture can be divided into two categories as the institutional sensitive and the local community sensitive.
Originality/value
This study is not only an exploitation of imprinting theories, but also provides a different understanding of organizational evolution, especially in terms of imprints dynamic. Meanwhile, the case shows how institutional environment and local community has shaped differently the organizational culture.
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Yunpeng Wang and Roger E. Khayat
The purpose of this study is to examine theoretically the axisymmetric flow of a steady free-surface jet emerging from a tube for high inertia flow and moderate surface tension…
Abstract
Purpose
The purpose of this study is to examine theoretically the axisymmetric flow of a steady free-surface jet emerging from a tube for high inertia flow and moderate surface tension effect.
Design/methodology/approach
The method of matched asymptotic expansion is used to explore the rich dynamics near the exit where a stress singularity occurs. A boundary layer approach is also proposed to capture the flow further downstream where the free surface layer has grown significantly.
Findings
The jet is found to always contract near the tube exit. In contrast to existing numerical studies, the author explores the strength of upstream influence and the flow in the wall layer, resulting from jet contraction. This influence becomes particularly evident from the nonlinear pressure dependence on the upstream distance, as well as the pressure undershoot and overshoot at the exit for weak and strong gravity levels, respectively. The approach is validated against existing experimental and numerical data for the jet profile and centerline velocity where good agreement is obtained. Far from the exit, the author shows how the solution in the diffusive region can be matched to the inviscid far solution, providing the desired appropriate initial condition for the inviscid far flow solution. The location, at which the velocity becomes uniform across the jet, depends strongly on the gravity level and exhibits a non-monotonic behavior with respect to gravity and applied pressure gradient. The author finds that under weak gravity, surface tension has little influence on the final jet radius. The work is a crucial supplement to the existing numerical literature.
Originality/value
Given the presence of the stress singularity at the exit, the work constitutes a superior alternative to a computational approach where the singularity is typically and inaccurately smoothed over. In contrast, in the present study, the singularity is entirely circumvented. Moreover, the flow details are better elucidated, and the various scales involved in different regions are better identified.
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