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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.).

This paper aims to analyze influences on the adoption of an application launched by some airlines and independent providers, called “social seating”, which is based on user profiles from or similar to social networks. These applications have not been widely successful, and therefore constitute an interesting exception within the area of social networking, warranting further investigation.

An empirical study based on the technology acceptance model and using survey methodology has been undertaken to understand antecedents of adoption and use of such applications.

Results show a consistent influence of perceived ease of use on perceived usefulness, as well as a strong role of privacy and data security.

Due to the limited adoption, the actual use could only be investigated using a small data set, while the majority of results rely on stated intentions.

This is one of a few studies that focuses on a social networking application that both crosses into the physical world, and that has been very limited in adoption and success.

The wetting performance and intermetallic formation of a Sn/Ag/Cu alloy on printed circuit board (PCB) surfaces and on component terminations were studied in this work. Two different PCB surface finishes, immersion gold over electroless nickel (Ni/Au) and an organic solderability preservative (OSP), were studied. Chip components with Sn/Pb coating and a gull‐wing type component with 100% Sn coating were used in these experiments. Different reflow profiles were tested, and the dependence of the wetting performance, intermetallic layer thickness and the microstructure of the solder joints on the reflow profile were investigated.It was found that reflow process conditions did not significantly influence the spreading or intermetallic formation on either of the surfaces. Neither the wetting onto the component nor the general microstructure of the solder joints varied significantly with the reflow profile. When a Sn/Pb ‐coated component was used, the content and size of Pb‐rich phases in the solder joint increased with a longer time above liquidus or a higher reflow peak temperature.

The benefits of Nitraclean I nitrogen inerted reflow soldering are well documented. However, there has been some debate as to the maximum oxygen level that can be tolerated by different types of paste if those benefits are to be realised. It is demonstrated that, for all paste types, solder balls decrease and the spread factor increases with increasing oxygen level, but that it has little effect on either joint strength or microstructure. It is concluded that for RMApastes a maximum oxygen level of 1000 ppm is required and that for low residue pastes the level needs to be reduced to 200 ppm for optimum results.

Several effects of the atmosphere in the soldering oven on both the soldering process itself and the soldering results are discussed. Experiments have been undertaken to compare the results of soldering in air and in nitrogen containing 10,100 and 1000 ppm oxygen, in which, e.g., discolouration, wettability, solderability after reflow, solder bridging and solder‐ball formation were investigated. Unmounted FR‐4 testboards with both an RMA solder paste of known high quality and a low‐residue paste were used. Mounted test boards were used to analyse the self‐alignment of components and to compare the levels of soldering defects obtained in air and in nitrogen. The test results show that a nitrogen atmosphere containing 1000 ppm of oxygen or less is sufficiently pure to realise improved soldering conditions for most types of components. For the low‐residue paste tested, 1000 ppm is too high, but 100 ppm is sufficiently low. All effects on the soldering process will depend on the amount of oxygen in the gas. To produce an oven atmosphere of nitrogen with a very low amount of O2 (e.g., <100 ppm) is rather expensive, if this oven is to work under production conditions. Will the extra cost of investment and gas consumption be worthwhile in view of a better production yield and higher product quality? The authors explain why they do not believe this to be the case.

The benefits of controlling the atmosphere in an infra‐red reflow oven are evident in improved soldering yields and easier post‐soldering cleaning of the assembly. The main benefits arise from reducing the oxygen partial pressure in the atmosphere at the time when the solder is molten. The most common inerting atmosphere used is nitrogen, and to reduce the oxygen concentration to 100 ppm is relatively straightforward, but below this level the equipment and the running costs increase with decreasing oxygen requirement. This paper gives data on the effects of reducing the oxygen level on a number of parameters relevant to high quality manufacture and product reliability. The aim is to identify which aspects of the soldering process are crucially sensitive to the oxygen concentration and which are not, in order to establish a good working compromise between oxygen level and the cost of its attainment.

In short-term forecasting of day-ahead electricity prices, incorporating intraday dependencies is vital for accurate predictions. However, it quickly leads to dimensionality problems, i.e. ill-defined models with too many parameters, which require an adequate remedy. This study addresses this issue.

In an application for the German/Austrian market, this study derives variable importance scores from a random forest algorithm, feeds the identified variables into a support vector machine and compares the resulting forecasting technique to other approaches (such as dynamic factor models, penalized regressions or Bayesian shrinkage) that are commonly used to resolve dimensionality problems.

This study develops full importance profiles stating which hours of which past days have the highest predictive power for specific hours in the future. Using the profile information in the forecasting setup leads to very promising results compared to the alternatives. Furthermore, the importance profiles provide a possible explanation why some forecasting methods are more accurate for certain hours of the day than others. They also help to explain why simple forecast combination schemes tend to outperform the full battery of models considered in the comprehensive comparative study.

With the information contained in the variable importance scores and the results of the extensive model comparison, this study essentially provides guidelines for variable and model selection in future electricity market research.

This chapter investigated tendering in stealth construction, emphasising innovative approaches and methodologies that prioritise environmental protection, safety, efficiency, and aesthetics. It began with an overview of the construction industry’s tendering processes, followed by an in-depth examination of various tendering types, including competitive and negotiated methods. The study highlighted contemporary trends such as electronic tendering, Building Information Modelling (BIM), green and sustainable procurement, risk management, data analytics, artificial intelligence, lean construction practices, and blockchain technology. Moreover, with a specific focus on stealth construction, the chapter further analysed certain criteria, including building cross-section development, visibility, radio frequency emission, and countermeasures. It explored integrating functional construction systems, including environmental, safety, health, and quality management. Additionally, it discussed methods like green building, modular construction, and low-impact techniques. Lastly, the chapter emphasised the strategies to achieve environmental protection, safety, speed, economy, and aesthetics in tendering for stealth construction.

The purpose of this paper is to determine if companies in the modular and offsite construction (MOC) industry are agile or not and its level of application for agility principles, which allows for quick responses to the increasingly dynamic nature of industry environments.

This paper proposes an agility assessment framework for MOC that uses 48 assessment attributes organized into four categories: metrics, drivers, enablers and capabilities. A questionnaire approach was used to disseminate the framework globally in 19 countries and synthesize its relevance to the MOC industry. The questionnaire had 55 complete responses, majority of respondents work in managerial positions for MOC manufacturing facilities and onsite general contractors.

It was found that the lowest metric score for adapting to change was for cost since controlling cost would be difficult for any changes required after the design freeze stage. The top agility driver was found to be the need to respond to the wide variety of customer expectations, while the lowest driver was the existence of competing priorities. The top agility enabler was vendor partnership, which can be related to current postpandemic supply chain disruptions. Regarding technological capabilities, Europe and the USA acquired better scores compared to Asia, Latin America and Africa.

This study contributes to the MOC body of knowledge by creating an agility assessment tool for MOC firms to analyze their agile approach and environment, identifying the preliminary importance of agility assessment attributes and determining significant agile differences between the main MOC industry groups.

For some years now, Cameroon has seen a significant increase in its electricity demand, and this need is bound to grow within the next few years owing to the current economic growth and the ambitious projects underway. Therefore, one of the state's priorities is the mastery of electricity demand. In order to get there, it would be helpful to have reliable forecasting tools. This study proposes a novel version of the discrete grey multivariate convolution model (ODGMC(1,N)).

Specifically, a linear corrective term is added to its structure, parameterisation is done in a way that is consistent to the modelling procedure and the cumulated forecasting function of ODGMC(1,N) is obtained through an iterative technique.

Results show that ODGMC(1,N) is more stable and can extract the relationships between the system's input variables. To demonstrate and validate the superiority of ODGMC(1,N), a practical example drawn from the projection of electricity demand in Cameroon till 2030 is used. The findings reveal that the proposed model has a higher prediction precision, with 1.74% mean absolute percentage error and 132.16 root mean square error.

These interesting results are due to (1) the stability of ODGMC(1,N) resulting from a good adequacy between parameters estimation and their implementation, (2) the addition of a term that takes into account the linear impact of time t on the model's performance and (3) the removal of irrelevant information from input data by wavelet transform filtration. Thus, the suggested ODGMC is a robust predictive and monitoring tool for tracking the evolution of electricity needs.