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The influence of buoyancy forces on oscillatory Marangoni flow in liquid bridges of different aspect ratio is investigated by three‐dimensional, time‐dependent numerical solutions and by laboratory experiments using a microscale apparatus and a thermographic visualisation system. Liquid bridges heated from above and from below are investigated. The numerical and experimental results show that for each aspect ratio and for both the heating conditions the onset of the Marangoni oscillatory flow is characterized by the appearance of a standing wave regime; after a certain time, a second transition to a travelling wave regime occurs. The three‐dimensional flow organization at the onset of instability is different according to whether the bridge is heated from above or from below. When the liquid bridge is heated from below, the critical Marangoni number is larger, the critical wave number (m) is smaller and the standing wave regime is more stable, compared with the case of the bridge heated from above. For the critical azimuthal wave number, two correlation laws are found as a function of the geometrical aspect ratio A.

This paper describes two accurate and efficient numerical methods for computing unsteady viscous flows. The first one solves the incompressible Navier‐Stokes equations in their vorticity‐velocity formulation, using a staggered‐grid finite‐volume spatial discretization to provide second‐order accuracy on arbitrary grids, and combines effectively an alternating direction implicit scheme for the vorticity transport equation and a multigrid line‐Gauss‐Seidel relaxation for the velocity equations. The second method solves the compressible Reynolds‐averaged Navier‐Stokes equations in strong conservation form, with a k−ω turbulence closure model. The equations are discretized in time using an implicit three‐time‐level scheme, combined with a dual time stepping approach, so that the residual at every physical time step is annihilated using an efficient multigrid Runge‐Kutta iteration with variable time stepping and implicit residual smoothing. The space discretization uses a Roe’s flux difference splitting for the convective terms and standard central differences for the diffusive ones. A turbulent unsteady cascade flow is used to demonstrate the accuracy and efficiency of the method. The authors are currently working towards extending the two approaches described in this paper to three space dimensions.

This paper aims to examine, through the lens of language expectancy theory (LET), how sustainability assurors use optimism and certainty in possible persuasion attempts. The paper also explores a number of explanatory variables that could offer insights into the use of these verbal tones in sustainability assurance reports.

First, the paper relies on DICTION standard normalised optimism and certainty ranges in conjunction with descriptive statistics to analyse how sustainability assurors use optimism and certainty. Second, the paper uses quantile regression with robust standard errors to investigate the association between the measures of verbal tone used in this study and several possible explanatory variables.

Consistent with LET, the study documents that sustainability assurors exercise caution in using both certainty and optimism in persuasion attempts. The paper also finds that possible explanatory variables significantly associated with optimism include praise, assurance level, legal system and report location. However, reference to sustainability management control (SMC), status of assurance providers, praise, legal system and financial performance appear to explain the use of certainty.

The paper does not, at this stage, claim causality between the two measures of verbal tone, on the one hand, and the possible explanatory variables explored, on the other hand. It rather reports their possible associations. Furthermore, the study only measures reference to management control system and not reliance on it.

The main findings of this study imply that the use of optimism and certainty exhibits likely cautious practice by assurors. Nevertheless, assurors are more likely to use certainty more flexibly and appear more discreet when using optimism.

The findings of this paper also indicate how societal expectations play an important role in ensuring cautious persuasive behaviour by sustainability assurors in using verbal tones within sustainability assurance statements. This suggests that stakeholders may place reliance on attestations expressed in these statements.

The paper represents the first attempt to test LET in sustainability accounting by analysing verbal tones used by sustainability assurance providers. It contributes to the sustainability assurance literature in that it empirically demonstrates how sustainability assurors, as expert communicators, use optimistic tone and verbal certainty in careful persuasion attempts.

The purpose of this paper is to present the development of a Matlab/Simulink‐based simulation environment for the design and testing of indirect and direct adaptive flight control laws with fault tolerant capabilities to deal with the occurrence of actuator and sensor failures.

The simulation environment features a modular architecture and a detailed graphical user interface for simulation scenario set‐up. Indirect adaptive flight control laws are implemented based on an optimal control design and frequency domain‐based online parameter estimation. Direct adaptive flight control laws consist of non‐linear dynamic inversion performed at a reference nominal flight condition augmented with artificial neural networks (NNs) to compensate for inversion errors and abnormal flight conditions following the occurrence of actuator or sensor failures. Failure detection, identification, and accommodation schemes relying on neural estimators are developed and implemented.

The simulation environment provides a valuable platform for the evaluation and validation of fault‐tolerant flight control laws.

The modularity of the simulation package allows rapid reconfiguration of control laws, aircraft model, and detection schemes. This flexibility allows the investigation of various design issues such as: the selection of control laws architecture (including the type of the neural augmentation), the tuning of NN parameters, the selection of parameter identification techniques, the effects of anti‐control saturation techniques, the selection and the tuning of the control allocation scheme, as well as the selection and tuning of the failure detection and identification schemes.

The novelty of this research efforts resides in the development and the integration of a comprehensive simulation environment allowing a very detailed validation of a number of control laws for the purpose of verifying the performance of actuator and sensor failure detection, identification, and accommodation schemes.

The purpose of this paper is to analyze and compare the performance of several different UAV trajectory tracking algorithms in normal and abnormal flight conditions to investigate the fault‐tolerant capabilities of a novel immunity‐based adaptive mechanism.

The evaluation of these algorithms is performed using the West Virginia University (WVU) UAV simulation environment. Three types of fixed‐parameter algorithms are considered as well as their adaptive versions obtained by adding an immunity‐based mechanism. The types of control laws investigated are: position proportional, integral, and derivative control, outer‐loop nonlinear dynamic inversion (NLDI), and extended NLDI. Actuator failures on the three channels and increased turbulence conditions are considered for several different flight paths. Specific and global performance metrics are defined based on trajectory tracking errors and control surface activity.

The performance of all of the adaptive controllers proves to be better than their fixed parameter counterparts during the presence of a failure in all cases considered.

The immunity inspired adaptation mechanism has promising potential to enhance the fault‐tolerant capabilities of autonomous flight control algorithms and the extension of its use at all levels within the control laws considered and in conjunction with other control architectures is worth investigating.

The WVU UAV simulation environment has been proved to be a valuable tool for autonomous flight algorithm development, testing, and evaluation in normal and abnormal flight conditions.

A novel adaptation mechanism is investigated for UAV control algorithms with fault‐tolerant capabilities. The issue of fault tolerance of UAV control laws has only been addressed in a limited manner in the literature, although it becomes critical in the context of imminent integration of UAVs within the commercial airspace.

The influence of gravity on the Marangoni flow instability in half zone liquid bridges in the case of liquid metals is investigated by direct 3D and time‐dependent simulation of the problem. The computations are carried out for different heating conditions and environments (zero g conditions and on ground liquid zone heated from above or from below). The case of cylindrical shape (simplified model) and of melt/air interface deformed by the effect of gravity (real conditions) are considered. The comparison among these situations gives insight into the separate (gravity) effects of buoyancy forces and of the free surface deviation with respect to straight configuration. Body‐fitted curvilinear co‐ordinates are adopted to handle the non‐cylindrical problem. The liquid bridge exhibits different behaviours according to the allowed bridge shape. If the shape is forced to be cylindrical, the flow field is stabilized in the case of heating from above and destabilized if gravity is reversed. If the deformation is taken into account, gravity always stabilizes the Marangoni flow regardless of its direction (parallel or antiparallel to the axis) and the 3D flow structure is different according to the heating condition (from above or from below). In the latter case, the critical Marangoni number is larger and the critical wave number is smaller, compared with the opposite condition. In addition, for Pr=0.02 (Gallium), a surprising heretofore unseen behaviour arises. No steady bifurcation occurs and the flow becomes unstable directly to oscillatory disturbances. This phenomenon has never been reported before in the case of low Prandtl number liquids.

In this paper we (a pracademic, a practitioner, and an academic) aim to explore the academic/practitioner gap in social marketing and offer recommendations to close it, while amplifying existing examples of best practice from within the field. We also propose a research agenda to spur dialog and guide further investigations in this area. Insights from prior research, coupled with the co-authors’ experience and observations, indicate that a disconnect does exist between academia and practice within social marketing, though it is admittedly and unsurprisingly not uniform across contexts and disciplinary areas. Given social marketing’s identity as a practice-oriented field, there are many existing examples of academic/practitioner collaboration and the successful linkage of theory and practice that deserve to be amplified. However, the challenges associated with the very different systems and structures affecting both worlds mean the disconnect is problematic enough to warrant systematic change to ensure the two worlds are more aligned.

This paper (a pracademic, a practitioner and an academic) explores the academic/practitioner gap in social marketing and offer recommendations to close it, while amplifying existing examples of best practice from within the field. The authors also propose a research agenda to spur dialog and guide further investigations in this area.

The authors suggest five key reasons that focus should be placed upon closing the academic/practitioner gap in social marketing: demonstrating societal value by contributing to practice; embedding and developing theories in practice; adding to the social marketing literature; contributing to social marketing teaching; and communicating the value and effectiveness of social marketing. To close the gap, the authors propose specific recommendations within four broad areas: marketing the academia and practitioner collaboration offer; building ongoing relationships; creating collaborative partnerships; and changing the publishing model ensuring communications are accessible to all. They also suggest ways for social marketing associations and peak bodies to play a role.

The concept of a disconnect between academia and practice is by no means new; it has been a pervasive issue across disciplines for decades. However, this issue has not been the subject of much discussion within the social marketing literature. Recommendations outlined in this paper serve as a starting point for discussion. The authors also acknowledge that due to long standing “bright spots” in the field, numerous examples currently exist. They place an emphasis upon highlighting these examples while illuminating a path forward.

Public-interest entities – among which are listed companies – are obliged to publish nonfinancial disclosure in some countries and regions. The European Commission established mandatory nonfinancial disclosure by Directive 2014/95/EU. While a large body of literature was developed on sustainability reporting quality (SRQ) in voluntary context, evidence about the effect of mandatory nonfinancial disclosure on SRQ is controversial and previous experiences worldwide did not make clear if obligatoriness improves SRQ. This chapter aims to bridge the gap of empirical evidence about this phenomenon in European countries, focusing on first implementation of new legislation by Italian and German companies. The research has an explorative character and it adopts content analysis methods performed on sustainability reporting practices of companies listed in FTSE-MIB and DAX 30. The analysis aims to understand if obligatoriness affects SRQ, causes some changes in reporting practices such as harmonizing Italian and German ones by performing a cross-country comparison. The findings suggest that obligatoriness improves reporting quality and, above all, it fills the gap between different countries by fostering the adoption of international guidelines and the consequent introduction of some content, such as materiality analysis and quantitative measures of social and environmental performance.