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A vapor permeation processes for the separation of aromatic compounds from aliphatic compounds
(2014)
A number of rubbery and glassy membranes have been prepared and evaluated in vapor permeation experiments for separation of aromatic/aliphatic mixtures, using 5/95 (wt:wt) toluene/methylcyclohexane (MCH) as a model solution. Candidate membranes that met the required toluene/MCH selectivity of ≥ 10 were identified. The stability of the candidate membranes was tested by cycling the experiment between higher toluene concentrations and the original 5 wt% level. The best membrane produced has a toluene permeance of 280 gpu and a toluene/MCH selectivity of 13 when tested with a vapor feed of the model mixture at its boiling point and at atmospheric pressure. When a series of related membrane materials are compared, there is a sharp trade-off between membrane permeance and membrane selectivity. A process design study based on the experimental results was conducted. The best preliminary membrane design uses 45% of the energy of a conventional distillation process.
Global trade is plagued by slow and inefficient manual processes associated with physical documents. Firms are constantly looking for new ways to improve transparency and increase the resilience of their supply chains. This can be solved by the digitalisation of supply chains and the automation of document- and information-sharing processes. Blockchain is touted as a solution to these issues due to its unique combination of features, such as immutability, decentralisation and transparency. A lack of business cases that quantify the costs and benefits causes uncertainty regarding the truth of these claims. This paper explores how the costs and benefits of a blockchain-based solution for digitalising and automating documentation flows in cross-border supply chains compare to a conventional centralised relational database solution. The research described in this paper uses primary data collected through semi-structured interviews with industry experts, as well as secondary data from literature. Two models based on existing services were developed and the costs and benefits compared and then analysed using the Architecture Trade-off Analysis Method (ATAM) and the Analytic Network Process (ANP). Findings from the analysis show that a consortium blockchain solution like TradeLens is the favourable solution for digitalising and automating information flows in cross-border supply chains.
Student-faculty interactions that promote learning are essential contributors to student retention, academic success and satisfaction. But the factors that causally initiate and frame these interactions are not well understood. Only if students evaluate these interactions as positive will they seek them. We conducted a survey experiment with students (n = 375) from a tuition-fee-free German business school, using conditional process analysis to assess which factors frame effective interactions. We focus on out-of-classroom standard and non-standard requests that students make to faculty, then investigate how faculty and student gender and students’ academic entitlement influence the interaction. Our study examines how students evaluate the interaction with faculty: when they seek interaction, their expectations of getting their requests approved, and their disappointment when their requests are declined. We find a significant influence of the request type along with moderating effects of faculty gender, student gender and student entitlement, particularly for non-standard work requests. We conclude with policy implications for university management: developing target-group-specific measures that facilitate the desired and positively evaluated student-faculty interactions might benefit all university stakeholders.
Whether diversity enhances or impedes team creativity remains an issue of scholarly debate. Explanations of this ambiguity often lie in how diversity is both operationalized and measured. Eschewing the popular approach of using differences in objective criteria to signal diversity, a deep-level approach that focuses on differences in personal values is taken in this study. Value diversity is measured in the two forms of variety and separation and their associations with team creativity are explored. The investigation is augmented by considering the mediating role of team communication in these associations. The analysis was conducted on a sample of 98 teams, using both subjective and objective measures. The findings reveal that when considering value diversity in terms of variety, there is a positive association between diversity and team creativity. However, when the separation dimension of value diversity is considered, a negative association between diversity and team creativity is identified. Complex pathways pertaining to the role of communication within these relationships are also uncovered. In moving beyond rudimentary categories and measurement of diversity, this study further elucidates the complexity of the diversity–creativity relationship. Conclusions are drawn and implications for further research and managerial practice are derived.
Climate change is one of the key challenges of this century due to its impact on society and the economy. Students are asking their business schools to scale up climate change education (CCE) across all disciplines, and employers are looking for graduates ready to work on solutions. This desire for solutions is shared by faculty; however, in a recent survey, many highlighted that they lack knowledge about climate change mitigation and how to integrate CCE into their disciplines.
This chapter supports lecturers, professors and senior management in their journey to get an overview of CCE and, more importantly, to find high-impact climate solutions to be integrated and assessed in their teaching units.
Comparative analysis of the chemical and rheological curing kinetics of formaldehyde-based wood adhesives is crucial for assessing their respective performance. Differential scanning calorimetry (DSC) and rheometry are the conventional techniques used for monitoring the curing processes leading to crosslinking polymerization of the adhesives. However, the direct comparison of these techniques is inappropriate due to the intrinsic differences in their underlying procedures. To address this challenge, the two adhesive samples were sequentially cured, firstly with rheometry and followed by DSC. The observed higher curing degree in the subsequent DSC procedure underpins the incomplete curing of the samples during initial rheometry. Furthermore, the comparative assessment of the activation energies, molar ratios, and active groups of the two adhesives highlights the importance of the pre-exponential factor in addition to the activation energies, as it attributes to the probability of active groups coinciding at the appropriate spatial arrangement.
Context-aware systems to support actors in the operating room depending on the status of the intervention require knowledge about the current situation in the intra-operative area. In literature, solutions to achieve situation awareness already exist for specific use cases, but applicability and transferability to other conditions are less addressed. It is assumed that a unified solution that can be adapted to different processes and sensors would allow for greater flexibility, applicability, and thus transferability to different applications. To enable a flexible and intervention-independent system, this work proposes a concept for an adaptable situation recognition system. The system consists of four layers with several modular components for different functionalities. The feasibility is demonstrated via prototypical implementation and functional evaluation of a first basic framework prototype. Further development goal is the stepwise extension of the prototype.
The aim of this work was to investigate the mean fill weight control of a continuous capsule-filling process, whether it is possible to derive controller settings from an appendant process model. To that end, a system composed out of fully automated capsule filler and an online gravimetric scale was used to control the filled weight. This setup allows to examine challenges associated with continuous manufacturing processes, such as variations in the amount of active pharmaceutical ingredient (API) in the mixture due to fluctuations of the feeders or due to altered excipient batch qualities. Two types of controllers were investigated: a feedback control and a combination of feedback and feedforward control. Although both of those are common in the industry, determining the optimal parameter settings remains an issue. In this study, we developed a method to derive the control parameters based on process models in order to obtain optimal control for each filled product. Determined via rapid automated process development (RAPD), this method is an effective and fast way of determining control parameters. The method allowed us to optimize the weight control for three pharmaceutical excipients. By conducting experiments, we verified the feasibility of the proposed method and studied the dynamics of the controlled system. Our work provides important basic data on how capsule filler can be implemented into continuous manufacturing systems.
We examine the role of communication from users on dropout from digital learning systems to answer the following questions: (1) how does the sentiment within qualitative signals (user comments) affect dropout rates? (2) does the variance in the proportion of positive and negative sentiments affect dropout rates? (3) how do quantitative signals (e.g. likes) moderate the effect of the qualitative signals? and (4) how does the effect of qualitative signals on dropout rates change across early and late stages of learning? Our hypotheses draws from learning theory and self-regulation theory, and were tested using data of 447 learning videos across 32 series of online tutorials, spanning 12 different fields of learning. The findings indicate a main effect of negative sentiment on dropout rates but no effect of positive sentiment on preventing dropout behaviour. This main effect is stronger in the early stages of learning and weakens at later stages. We also observe an effect of the extent of variance of positive and negative sentiments on dropout behaviour. The effects are negatively moderated by quantitative signals. Overall, making commenting more broad-based rather than polarised can be a useful strategy in managing learning, transferring knowledge, and building consensus.
In increasingly complex production environments, tremendous efforts are being made to optimize the efficiency of a production system. An important efficiency factor is industrial maintenance, both influencing the cost and securing the technical availability of machines and components. Maintenance managers are required to deliver the necessary availability of the production system while minimizing the resources needed to do so. To make this possible, a method to evaluate the dependency between the technical availability of an entire production system and maintenance resources is necessary. This paper presents a systematic literature review of such methods is presented. In order to assess the methods proposed in the literature, first, requirements are developed, including a necessary focus on maintenance strategies within these methods. Including maintenance strategies is necessary since they provide the foundation for both the availability of a component and the maintenance resources needed. In total, 13 requirements are developed, and 21 different methods are evaluated. Only one of the proposed methods addresses all requirements, with others lacking possible combinations of maintenance strategies and the resulting influences on the production system.