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Several times in his IMechE/BP 1987 Tribology Paper — pages 4–11 of this issue — the author, Michael Monaghan, Technical Director of Ricardo Consultants plc, refers to early automotive engine developments and to the prevailing dilemma as to whether it was better — usually meaning less difficult or less costly — to seek increased performance by attending to the combustion system, or by reducing mechanical friction which dissipated a goodly portion of engine output long before it reached the road wheels.

The purpose of this paper is to analyse the packaged food market in Brazil by examining the use of nutrition and health claims and marketing techniques, as well as the different levels of industrial food processing in relation to product category, nutrition information and price.

A survey was conducted on the labels of pre-packed foods and non-alcoholic beverages marketed in a home-shopping website in Brazil.

The authors showed that the use of nutrition and health claims on packaged foods in Brazil is widespread and varied across different food categories. Marketing techniques were also prevalent, and techniques emphasising general health, well-being or naturalness were the most frequent type used. Overall, products carrying nutrition and health claims and/or using marketing techniques had lower content of fat and higher content of fibre. However, the high prevalence of these strategies in ultra-processed foods is alarming. The presence of health claims and use of marketing techniques was not found to be an effective modifier of the three price measures. However, processed and ultra-processed foods were more expensive than unprocessed foods when considering price per energy and price per 100 g or mL.

These results indicate that there are clear opportunities to improve the packaged food environment in supermarkets. It is important to highlight the need to develop public policies to address these issues, including restriction of the promotion and advertising of unhealthy foods and beverages and use of warning labels.

This new paper aims to extend the authors’ previous contributions about open-loop aircraft flutter test to closed-loop aircraft flutter test by virtue of the proposed direct data–driven strategy. After feeding back the output signal to the input and introducing one feedback controller in the adding feedback loop, two parts, i.e. unknown aircraft flutter model and unknown feedback controller, exist in this closed-loop aircraft flutter system, simultaneously, whose input and output are all corrupted with external noise. Because of the relations between aircraft flutter model parameters and the unknown aircraft model, direct data–driven identification is proposed to identify that aircraft flutter model, then some identification algorithms and their statistical analysis are given through the authors’ own derivations. As the feedback controller can suppress the aircraft flutter or guarantee the flutter response converge to one desired constant value, the direct data–driven control is applied to design that feedback controller only through the observed data sequence directly. Numerical simulation results have demonstrated the efficiency of the proposed direct data–driven strategy. Generally, during our new information age, direct data–driven strategy is widely applied around our living life.

First, consider one more complex closed loop stochastic aircraft flutter model, whose input–output are all corrupted with external noise. Second, for the identification problem of closed-loop aircraft flutter model parameters, new identification algorithm and some considerations are given to the corresponding direct data–driven identification. Third, to design that feedback controller, existing in that closed-loop aircraft flutter model, direct data–driven control is proposed to design the feedback controller, which suppresses the flutter response actively.

A novel direct data–driven strategy is proposed to achieve the dual missions, i.e. identification and control for closed-loop aircraft flutter test. First, direct data–driven identification is applied to identify that unknown aircraft flutter model being related with aircraft flutter model parameters identification. Second, direct data–driven control is proposed to design that feedback controller.

To the best of the authors’ knowledge, this new paper extends the authors’ previous contributions about open-loop aircraft flutter test to closed-loop aircraft flutter test by virtue of the proposed direct data–driven strategy. Consider the identification problem of aircraft flutter model parameters within the presented closed loop environment, direct data–driven identification algorithm is proposed to achieve the identification goal. Direct data–driven control is proposed to design the feedback controller, i.e. only using the observed data to design the feedback controller.

This new paper aims to combine the recent new contributions about direct data driven control and other safety property to form an innovative direct data driven safety control for aircraft flight system. More specifically, within the framework of direct data driven strategy, the collected data are dealt with to get the identified plant and designed controller. After reviewing some priori information about aircraft flight system, a closed loop system with the unknown plant and controller simultaneously is considered. Data driven estimation is proposed to identify the plant and controller only through the ratios of two correlation functions, computed from the collected data. To achieve the dual missions about perfect tracking and safety property, a new notion about safety controller is introduced. To design this safety controller, direct data driven safety controller is proposed to solve one constrain optimization problem. Then the authors apply the Karush–Kuhn–Tucker (KKT) optimality conditions to derive the explicit safety controller.

First, consider one closed loop system corresponding to aircraft flight system with the unknown plant and feed forward controller, data driven estimation is used to identify the plant and feed forward controller. This identification process means nonparametric estimation. Second, to achieve the perfect tracking one given transfer function and guarantee the closed loop output response within one limited range simultaneously, safety property is introduced. Then direct data driven safety control is proposed to design the safety controller, while satisfying the dual goals. Third, as the data driven estimation and direct data driven safety control are all formulated as one constrain optimization problem, the KKT optimality conditions are applied to obtain the explicit safety controller.

Some aircraft system identification and aircraft flight controller design can be reformulated as their corresponding constrain optimization problems. Then through solving these constrain optimization problems, the optimal estimation and controller are yielded, while satisfying our own priori goals. First, data driven estimation is proposed to get the rough estimation about the plant and controller. Second, data driven safety control is proposed to get one safety controller before our mentioned safety concept.

To the best of the authors’ knowledge, some existing theories about nonparametric estimation and tube model predictive control are very mature, but few contributions are applied in practice, such as aircraft system identification and aircraft flight controller design. This new paper shows the new theories about data driven estimation and data driven safety control on aircraft, being corresponded to the classical nonparametric estimation and tube model predictive control. Specifically, data driven estimation gives the rough estimations for the aircraft and its feed forward controller. Furthermore, after introducing the safety concept, data driven safety control is introduced to achieve the desired dual missions with the combination of KKT optimality conditions.

This study aims to evaluate the carbohydrate content, ingredient profile and degree of processing of supposedly “low-carb” foods in the Brazilian market.

Information was collected from physical supermarkets in Divinópolis, Minas Gerais and on websites throughout Brazil between July and September/2020. The carbohydrate content was assessed in g/100 g, and ingredient lists were investigated for the presence of carbohydrate-rich ingredients. The degree of processing of the products was evaluated by NOVA classification to determine whether the term “low carb” had been translated into Portuguese.

This study evaluated a total number of 164 products, the most frequent were bakery products (34.7%), granola and cereal bars (19.5%) and candies and desserts (14.0%). This claim was also found in low-carb foods such as cheese and chicken. Most food products evaluated (56.0%) were classified as ultra-processed, with the group having the highest carbohydrate content (20.0; 3.0–47.5g/100g), compared to products classified as processed foods (p < 0.01). The ingredient lists showed items rich in carbohydrates, such as cassava and corn derivatives. In 162 products, a low-carb claim was displayed without translation into Portuguese. These data demonstrate that most of these products are ultra-processed and have a high glycidic content.

To the best of the authors’ knowledge, the study was a pioneer investigation of the ingredients of “low-carb” foods, their carbohydrate composition and their degree of processing based on the NOVA classification.

This study aims to understand if an online dating app is considered an acceptable channel to conduct advertising activities and understand the differences between Generations X, Y and Z for such acceptance.

A total of 411 Tinder users’ reactions were obtained and analyzed using text mining to compute the sentiment score of each response, and a Kruskal–Wallis H test to verify if there are statistical differences between each generation.

The results showed positive acceptability toward the marketing campaign on Tinder, especially Z Generation. Nevertheless, the statistical analysis revealed that the differences between each generation are not statistically significant.

The main limitation relates to the fact that the participants, during the data collection, revealed their identification, perhaps leading to acquiescence bias. In addition, the study mainly covered the male population. A balanced sample would be positive to examine any possible differences between gender.

Results provide an essential indication for companies regarding their marketing activities conducted on Tinder to fully exploit the possibility of using Tinder as an alternative and valuable channel to conduct marketing activities.

Up until now, no studies tried to understand the effect of a marketing activity online on an online dating app.

The notes reproduced here were taken by Glenn Johnson in Lloyd Mints’ course on Money and Banking at the University of Chicago in the fall of 1946. Several additional sets of course notes taken by Glenn Johnson have been published in the archival volumes of Research in the History of Economic Thought and Methodology. These included notes from Frank Knight's course on economic theory (Volume 24C) and Albert L. Meyer's course entitled elements of modern economics (appearing in this volume). A brief biography of Glenn Johnson is provided in Volume 24C, along with notes from his course on Agricultural Economics Methodology taught at Michigan State University.

This paper aims to present a SPICE model to represent antennas in receiving mode. The model can be used to evaluate the performance of the antenna when it is coupled to several different nonlinear electric circuits. The proposed methodology is particularly suitable for rectenna applications, as it allows the analysis of different configurations for a rectenna more efficiently than using full-wave analysis simulators coupled directly to each rectifier circuit.

The model presented uses reciprocity theory to calculate the ideal voltage source of the Thevenin-equivalent circuit for an antenna. Vector fitting is then used to approximate the model to rational functions that can be converted to Resistor, Inductor and Capacitor circuits. Additional components are added to the circuit to prevent numerical instability.

Two rectennas are used to illustrate the performance of the proposed model, one based on a 2.45-GHz rectangular patch antenna and another based on a planar spiral antenna. The second antenna has impedance with positive and negative real parts along the frequency range, which could lead to numerical instabilities. The proposed method is shown to be stable while working with these negative resistance values, which may appear during circuit parameterization.

The equivalent SPICE circuit model for the antenna makes it easy to simulate nonlinear circuits connected to the antenna and perform transient analyses. The computational cost of antenna analysis is reduced, being more computationally efficient than methods that involve full-wave simulation. This characteristic makes it an interesting approach for working with rectennas, or any application where the time constant of the circuit is much longer than the period of the incident wave.

For most antenna applications, the numerical stability of the circuit can be achieved using passive enforcement. However, depending on the phase response of the antenna, the impedance that represents its far-field characteristic may present a negative real part, in which case, passive enforcement will fail. In this paper, the problem of numerical instability is solved by introducing an offset resistance and a current-controlled voltage source to the model.

This paper aims to investigate the factors associated with the voluntary disclosure of integrated reporting (IR) in Brazil of the companies listed on the stock exchange – Brasil, Bolsa, Balcão. The cultural dimensions of a nation reflect different priorities in accounting practices. The Brazilian case, therefore, becomes significant, as Brazil is increasingly important in world markets.

As an explanatory econometric model, multinomial logistic regression was used (Y = 2 to describe the probability of the IR disclosure; Y = 1 to describe the occurrence of reports with practices similar to the IR and Y = 0 to describe the occurrence of non-disclosure of non-financial reports). Applied to panel data with random effects (chosen for best performance) in the period from 2016 to 2019.

Reveals the positive association of the company’s profitability and market-to-book with the probability of the IR disclosure. Regarding the board composition, it is suggested that size does not make a difference, with the greater participation of women and independence of directors associated with better probabilities of adopting the IR in Brazil.

This work is the first to characterize the Brazilian reality of voluntary disclosure, specifying the implementation of IR, compared to publishing reports similar to the IR and not reporting structured non-financial statements. It can also be considered the first study on the relevance of the board structure in the disclosure of IR by Brazilian companies. Finally, it contributes to the literature on IR adoption, bringing practical results in understanding the most favorable conditions in which the IR framework will be fully implemented.