Study of industrial titania synthesis using a hybrid particle-number and detailed particle model

We apply a hybrid particle model to study synthesis of particulate titania under representative industrial conditions. The hybrid particle model employs a particle-number description for small particles, and resolves complicated particle morphology where required using a detailed particle model. This enables resolution of particle property distributions under fast process dynamics. Robustness is demonstrated in a network of reactors used to simulate the industrial process. The detailed particle model resolves properties of the particles that determine end product quality and post-processing efficiency, including primary particle size and degree of aggregate cohesion. Sensitivity of these properties to process design choices is quantified, showing that higher temperature injections produce more sintered particles; more frequent injections narrow the geometric standard deviation of primary particle diameter; and chlorine dilution reduces particle size and size variance. Structures of a typical industrial particle are compared visually with simulated particles, illustrating similar aggregate features with slightly larger primary particles

The governance of inter-firm co-development projects in an open innovation setting

Purpose: The purpose of this paper is to examine the governance of inter-firm co-development in an open innovation setting and show how a stage-gate product development process can be used to support this relationship. Design/methodology/approach: The authors adopt a qualitative case-study approach informed by ethnomethodology. Data were obtained via semi-structured interviews and document analysis. Findings: They found that in an open innovation setting – where the producing partner relies on a research partner for all product development activities – a stage-gate product development process can act as a governance mechanism, as it enables the development of trust and cooperation which supports the co-development relationship. Research limitations/implications: The implication of this finding is that a stage-gate process can be a flexible governance mechanism, which can adapt over time in relation to the needs of the co-development partners in an open innovation setting. This also lays the groundwork for future research to explore the applicability of this tool in other settings, e.g. outsourcing arrangements as well as help guide the design and implementation of future governance mechanisms. Originality/value: In the context of accounting research, this paper helps practitioners and academics understand how a stage-gate process can be used as a governance mechanism to manage and control co-development projects in an open innovation setting

A new methodology to calculate process rates in a kinetic Monte Carlo model of PAH growth

This paper develops a new methodology to calculate the process rates in a kinetic Monte Carlo (KMC) model of polycyclic aromatic hydrocarbon (PAH) growth. The methodology uses a combination of the steady-state and partial-equilibrium approximations. It shows good agreement with the results from simulations using a detailed chemical mechanism under conditions relevant to flames (temperatures between 1000 and 2500 K, equivalence ratios between 0.5 and 10). The new methodology is used to calculate the rate of different stochastic processes in KMC simulations of PAH growth of premixed ethylene-oxygen flames. The resulting rates are only a function of temperature and the main gas-phase species present in the flame environment. The results of the KMC model are shown to be consistent with the concentrations of species calculated using a well-established mechanism for the growth of small PAH species

Bivariate extension of the moment projection method for the particle population balance dynamics

This work presents a bivariate extension of the moment projection method (BVMPM) for solving the two-dimensional population balance equations involving particle inception, growth, shrinkage, coagulation and fragmentation. A two–dimensional Blumstein and Wheeler algorithm is proposed to generate a set of weighted particles that approximate the number density function. With this algorithm, the number of the smallest particles can be directly tracked, closing the shrinkage and fragmentation moment source terms. The performance of BVMPM has been tested against the hybrid method of moments (HMOM) and the stochastic method. Results suggest that BVMPM can achieve higher accuracy than HMOM in treating shrinkage and fragmentation processes where the number of the smallest particles plays an important role

A joint moment projection method and maximum entropy approach for simulation of soot formation and oxidation in diesel engines

A joint moment projection method and maximum entropy approach for treating the soot population balance equations is developed and presented in this work. The moment projection method is used to solve the population balance equations and generate moments that are supplied to the maximum entropy approach as a post-processing technique to reconstruct the soot particle size distribution. The particle size range required by the maximum entropy for particle size distribution reconstruction is determined based on the weighted particles generated in the moment projection method. The performance of the joint approach is first evaluated by solving a set of simplified population balance equations in Matlab, then it is implemented into a Stochastic Reactor Model engine code to simulate the formation and oxidation of soot particles in a single-cylinder direct injection diesel engine. Results suggest that the joint approach has the advantages of ease of implementation, high accuracy and low computational cost. It enables a detailed analysis on the soot formation and oxidation processes in diesel engines. Complete information on the soot particle size distribution can be provided with little CPU cost induced

Modelling PAH curvature in laminar premixed flames using a detailed population balance model

© 2016 The Combustion Institute A detailed population balance model, which includes the kinetic Monte Carlo-aromatic site (KMC-ARS) model for detailed polycyclic aromatic hydrocarbon (PAH) growth, is used to compute the Gauss curvature of PAHs in laminar premixed ethylene and benzene flames. Previous studies have found that capping of an embedded 5-member ring causes curvature in graphene edges. In this work, a capping process is added to the KMC-ARS model with the rate coefficient of the capping reaction taken from the work of You et al. (2011). We demonstrate that the Gauss–Bonnet theorem can be used to derive a correlation between the number of 5- and 6-member rings in a PAH and its Gauss curvature (or radius of curvature), independent of where the 5-member ring is embedded within the PAH structure. Numerical simulation yields satisfactory results when compared to the experimentally determined Gauss curvature reported in the literature. Computed and experimental fringe length distributions are also compared and the results suggest that PAHs smaller than the size required for inception are able to condense onto particles.This research is supported by the National Research Foundation, Prime Minister’s Office, Singapore under its CREATE programme. Mr. Edward K. Y. Yapp was supported by the Gates Cambridge, Cambridge, UK. Prof. Markus Kraft was supported by the Weierstrass Institute for Applied Analysis and Stochastics, Berlin, Germany

Management controls and pressure groups: the mediation of overflows

Purpose: Organisations produce effects that go beyond the economic framing within which they operate, referred to as overflows in this paper. When an organisation comes under pressure to address these overflows they must decide how to respond. Previous research has placed social and environmental reporting as an important tool organisations mobilise in their attempts to mediate these pressures and the groups that give rise to them. However, these reports are typically only released once a year while the pressures that organisations face can arise at any time and are ongoing and constant. The purpose of this paper is to explore situated organisational practices and examine if and how management controls are mobilised in relation to the actions of pressure groups. Design/methodology/approach: This paper takes a case study approach to understand how an organisation attempts to mediate the pressures from a number of overflows: carbon emissions, changing lifestyles, aspartame and obesity. To undertake this research a performative understanding of management control is utilised. This focusses the research on if and how management controls are mobilised to assist with attempts to mediate pressures. Findings: Analysis of the data shows that many different management controls, beyond just reports, were mobilised during the attempts to mediate the pressure arising from the actions of groups affected by the overflows. The management controls were utilised to: identify pressures, demonstrate how the pressure had been addressed, alleviate the pressure or to dispute the legitimacy of the pressure. Originality/value: This paper shows the potential for new connections to be made between the management control and social and environmental accounting literatures. It demonstrates that future research may gain much from examining the management controls mobilised within the situated practices that constitute an organisations response to the pressures it faces

How management control practices enable strategic alignment during the product development process

Purpose - This paper examines how the management control practices of organization members enable the alignment of product development projects with potentially conflicting corporate strategies during the product development process. Methodology/approach - Using an ethnomethodology informed research approach, we carry out a case study of an innovative New Zealand food company. Case study data included an internal company document, interviews with organization members, and an external market analysis document. Findings - Our case study company had both sales growth and profit growth corporate strategies which have been argued to cause tensions. We found that four management control practices enabled the alignment of product development projects to these strategies. The first management control practice was having the NPD and marketing functions responsible for different corporate strategies. Other management control practices included the involvement of organization members from across multiple functions, the activities they carried out, and the measures used to evaluate project performance during the product development process. Research limitations/implications - These findings add new insights to the management accounting literature by showing how a combination of management control practices can be used by organization members to align projects with potentially conflicting corporate strategies during the product development process. Practical implications - While the alignment of product development projects to corporate strategy is not easy this study shows how it can be enabled through a number of management control practices. Originality/value - We contribute to the management accounting research in this area by extending our understanding of the management control practices used during the product development process

Core values as a management control in the construction of "sustainable development"

Purpose - This paper aims to examine a management control constructed by senior managers, a core value focused on sustainability, as it travels through time and space. The criticality of sustainable development suggests the need to understand the effects that core values have on organisational actions. Design/methodology/approach - A case study methodology carried out at a multinational organisation is used. This analysis was informed by an actor-network theory which allowed placing the organisation's sustainability focused core value at the centre of this research. Findings - It was found that management control, in the form of a sustainability-focused core value, took on an active role in the case organisation. This enabled the opening of space and time that allowed actors to step forward and take action in relation to sustainable development. It is shown how the core value mobilised individual actors at specific points in time but did not enrol enough collective support to continue its travel. The resulting activities, though, provided a construction of sustainable development within the organisation more in line with traditional profit-seeking objectives rather than in relation to sustainability objectives, such as inter- and intra-generational equity. Research limitations/implications - These findings suggest possibilities for future research that examines the active role that management controls may take within sustainable development. Originality/value - This paper shows the active role a management control, a sustainability focused core value, took within an organisation. This builds on the research that examines management control in relation to sustainability issues and sustainable development as well as the literature that examines core values

Polar curved polycyclic aromatic hydrocarbons in soot formation

© 2018 The Combustion Institute. In this paper, we consider the impact of polar curved polycyclic aromatic hydrocarbons (cPAH) on the process of soot formation by employing electronic structure calculations to determine the earliest onset of curvature integration and the binding energy of curved homodimers. The earliest (smallest size) onset of curvature integration was found to be a six ring PAH with at least one pentagonal ring. The σ bonding in the presence of pentagons led to curvature, however, the π bonding strongly favored a planar geometry delaying the onset of curvature and therefore the induction of a flexoelectric dipole moment. The binding energies of cPAH dimers were found to be of similar magnitude to flat PAH containing one or two pentagons, with an alignment of the dipole moments vectors. For the more curved structures, steric effects reduced the dispersion interactions to significantly reduce the interaction energy compared with flat PAH. Homogeneous nucleation of cPAH at flame temperatures then appears unlikely, however, significant interactions are expected between chemi-ions and polar cPAH molecules suggesting heterogeneous nucleation should be explored.This project is supported by the National Research Foundation (NRF), Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme