Flow field of impinging sweeping jets

Sweeping jets are oscillating jets generated by fluidic oscillators, i.e., devices designed to produce an oscillation of the flow without the use of any moving parts (Raghu, 2013). A typical configuration of such devices consists of an expansion chamber connected to a high-pressure supply via a converging nozzle and provided with feedback channels. The oscillating motion in the expansion chamber is triggered by an inherent flow instability and sustained by the flow rate across the feedback channels. Recently, sweeping jets have been studied in flow control applications for noise reduction, separation and circulation control over airfoils, control of resonant cavity oscillations and deflection of jets. The advantageous features of fluidic actuators, among which are the wide range of operating frequencies (up to kHz with meso-scale) and the distributed momentum addition, have also stimulated an increasing interest in their application to electronics cooling. Several recent studies on the convective heat transfer from impinging sweeping jets (e.g., Hossain et al., 2018; Park et al., 2018) have shown that, compared to conventional round jets, they offer higher cooling rates with better uniformity at least for small jet-to-plate spacings.

Examining Public Organization Communication Misalignments During COVID-19 Through the Lens of Higher Education

COVID-19 is forcing alterations to administrative communication. Higher education institutions transitioning online during the pandemic offers a fertile ground to analyze what happens to organizational communication within administration when the mode is primarily remote. Using a content analysis of emails and participant interviews, this work finds that while administrators intend to communicate empathy, messages fall short of fostering connection with faculty due to failing to cultivate buyin through quality feedback channels. The takeaways of this study of remote communication is that despite its mode, communication must be two way, and the authenticity of organizational communication becomes more important under pressure-filled circumstances.

“Alexa, who am I?”: Voice Assistants and Hermeneutic Lemniscate as the Technologically Mediated Sense-Making

In this paper, I argue that AI-powered voice assistants, just as all technologies, actively mediate our interpretative structures, including values. I show this by explaining the productive role of technologies in the way people make sense of themselves and those around them. More specifically, I rely on the hermeneutics of Gadamer and the material hermeneutics of Ihde to develop a hermeneutic lemniscate as a principle of technologically mediated sense-making. The lemniscate principle links people, technologies and the sociocultural world in the joint production of meaning and explicates the feedback channels between the three counterparts. When people make sense of technologies, they necessarily engage their moral histories to comprehend new technologies and fit them in daily practices. As such, the lemniscate principle offers a chance to explore the moral dynamics taking place during technological appropriation. Using digital voice assistants as an example, I show how these AI-guided devices mediate our moral inclinations, decisions and even our values, while in parallel suggesting how to use and design them in an informed and critical way.

Designing a Customer Feedback Service Channel Through AI to Improve Customer Satisfaction in the Supermarket Industry

This study examines the impact of customer feedback channels on customer satisfaction, the need to design a new feedback channel using artificial intelligence (AI) as a goods locator map and internal survey model in the supermarket industry. A self-administered questionnaire was used to collect data from customers in supermarkets. Descriptive statistics and correlations were used to analyse the collected data sets to attain a statistically supported conclusion. The research found customer feedback service channels impacted on customers’ satisfaction. Customers were not satisfied with the rate of responsiveness to their feedback. The study designed and proposed a customer feedback service channel with AI as an alternative to existing feedback channels. It concluded that an AI designed system should be developed and implemented in supermarkets to test the intended outcome of the feedback channels and to design a robust system as a goods locator map and internal survey model.

Analysis of the Forces Driving the Oscillations in 3D Fluidic Oscillators

One of the main advantages of fluidic oscillators is that they do not have moving parts, which brings high reliability whenever being used in real applications. To use these devices in real applications, it is necessary to evaluate their performance, since each application requires a particular injected fluid momentum and frequency. In this paper, the performance of a given fluidic oscillator is evaluated at different Reynolds numbers via a 3D-computational fluid dynamics (CFD) analysis. The net momentum applied to the incoming jet is compared with the dynamic maximum stagnation pressure in the mixing chamber, to the dynamic output mass flow, to the dynamic feedback channels mass flow, to the pressure acting to both feedback channels outlets, and to the mixing chamber inlet jet oscillation angle. A perfect correlation between these parameters is obtained, therefore indicating the oscillation is triggered by the pressure momentum term applied to the jet at the feedback channels outlets. The paper proves that the stagnation pressure fluctuations appearing at the mixing chamber inclined walls are responsible for the pressure momentum term acting at the feedback channels outlets. Until now it was thought that the oscillations were driven by the mass flow flowing along the feedback channels, however in this paper it is proved that the oscillations are pressure driven. The peak to peak stagnation pressure fluctuations increase with increasing Reynolds number, and so does the pressure momentum term acting onto the mixing chamber inlet incoming jet.

Some New Results on the GaussianWiretap Feedback Channel

In this paper, the Gaussian wiretap feedback channel is revisited, and some new resultson its secrecy capacity are obtained. To be specific, first, we show that the Schalkwijk–Kailath (SK)feedback scheme, which achieves the secrecy capacity of the degraded Gaussian wiretap feedbackchannel, also achieves the secrecy capacity of the non-degraded Gaussian wiretap feedback channel.Second, applying the existing secret key-based feedback schemes to Gaussian wiretap feedbackchannels, we derive some new lower bounds on the secrecy capacities of these models. Finally,we compare the performances of the above feedback schemes in the degraded and non-degradedGaussian wiretap feedback channels and show which feedback scheme performs better for thesechannel models.