Theoretical Study of a Two-Degree-of-Freedom Piezoelectric Energy Harvester under Concurrent Aeroelastic and Base Excitation

This paper presents a study of a two-degree-of-freedom (2DOF) piezoelectric energy harvester (PEH) under concurrent aeroelastic and base excitation. The governing equations of the theoretical model under the combined excitation are developed and solved analytically using the harmonic balance method. Based on the electro-mechanical analogies, an equivalent circuit model is established. The energy harvesting performance of the 2DOF PEH under different wind speeds but the same base excitation is investigated. Voltage amplitudes of various response components with different frequencies are predicted by the analytical method and verified by the circuit simulation. The root-mean-square (RMS) voltage is used to measure the actual performance of the 2DOF PEH. Around the resonance state, the 2DOF PEH has been found to produce a larger voltage output than the conventional SDOF PEH. Moreover, several interesting phenomena, such as the quasi-periodic oscillation and the peak-to-valley transition, have been observed in the circuit simulation and explained by the analytical solution. The developed methodology in this paper can be easily adapted to analyze other similar types of multiple-degree-of-freedom (MDOF) PEHs under concurrent aeroelastic and base excitation.

Effects of defects and surface roughness on the vortex penetration and vortex dynamics in superconductor-insulator-superconductor multilayer structures exposed to RF magnetic fields: numerical simulations within TDGL theory

The vortex penetration and vortex dynamics are significantly important to superconducting devices, for example the superconducting cavities, since the vortex motions would create substantial dissipation. In experiments, different kinds of defects, as well as different degrees of surface roughness were observed. By considering these in superconductor-insulator-superconductor (SIS) structures, the vortex penetration and vortex dynamics are very complex due to the interactions with defects and the influence of surface roughness, especially for radio-frequency (RF) magnetic field, which are quite different from ideal defect-free SIS multilayer structures. In this paper, within Ginzburg-Landau theory, we perform numerical simulations to study the effects of nanoscale defects, surface roughness, and cracks in the coating layer on the vortex penetration and superheating field in Nb3Sn-I-Nb multilayer structures exposed to a quasi-static magnetic field. The validations of the numerical simulations are verified by good consistency with previous theoretical results in ideal defect-free SIS multilayer and single Nb structures. Furthermore, we explore the vortex dynamics and induced voltages in SIS multilayer structures exposed to RF magnetic fields for both ideal defect-free structures and real situations including surface roughness. Our numerical simulations indicate that, unlike the quasi-static case, the advantage of SIS multilayer structures over a single Nb structure depends on the degrees of surface roughness as well as the frequency and amplitude of the RF magnetic field. The results of this paper provide deep insight to evaluate the actual performance-limiting of next-generation superconducting radio-frequency (SRF) cavities with different proposed candidate materials, which are quite susceptible to nonideal surface.

An experimental performance comparison of Newtonian and non-Newtonian fluids on a centrifugal blood pump

The use of substitute fluid with similar rheological properties instead of blood is important due to ethical concerns and high blood volume consumption in pump performance test before clinical applications. The performance of a centrifugal blood pump with hydrodynamic journal bearing is experimentally tested using Newtonian 40% aqueous glycerin solution (GS) and non-Newtonian aqueous xanthan gum solution of 600 ppm (XGS) as working fluids. Experiments are performed at four different rotational speeds which are 2700, 3000, 3300, and 3600 rpm; experiments using GS reach between 8.5% and 37.2% higher head curve than experiments using the XGS for every rotational speed. It was observed that as the rotational speed and flow rate increase, the head curve difference between GS and XGS decreases. This result can be attributed to the friction reduction effect when using XGS in experiments at high rotation speed and high flow rate. Moreover, due to different fluid viscosities, differences in hydraulic efficiency were observed for both fluids. This study reveals that the use of Newtonian fluids as working fluids is not sufficient to determine the actual performance of a blood pump, and the performance effects of non-Newtonian fluids are remarkably important in pump performance optimizations.

Determination of Business Intelligence and Analytics-Based Healthcare Facility Management Key Performance Indicators

The use of digital technologies such as Internet of Things (IoT) and smart meters induces a huge data stack in facility management (FM). However, the use of data analysis techniques has remained limited to converting available data into information within activities performed in FM. In this context, business intelligence and analytics (BI&A) techniques can provide a promising opportunity to elaborate facility performance and discover measurable new FM key performance indicators (KPIs) since existing KPIs are too crude to discover actual performance of facilities. Beside this, there is no comprehensive study that covers BI&A activities and their importance level for healthcare FM. Therefore, this study aims to identify healthcare FM KPIs and their importance levels for the Turkish healthcare FM industry with the use of the AHP integrated PROMETHEE method. As a result of the study, ninety-eight healthcare FM KPIs, which are categorized under six categories, were found. The comparison of the findings with the literature review showed that there are some similarities and differences between countries’ FM healthcare ranks. Within this context, differences between countries can be related to the consideration of limited FM KPIs in the existing studies. Therefore, the proposed FM KPIs under this study are very comprehensive and detailed to measure and discover healthcare FM performance. This study can help professionals perform more detailed building performance analyses in FM. Additionally, findings from this study will pave the way for new developments in FM software and effective use of available data to enable lean FM processes in healthcare facilities.

Online and Offline Behavior Change Techniques to Promote a Healthy Lifestyle: A Qualitative Study

Combined lifestyle interventions (CLI) are focused on guiding clients with weight-related health risks into a healthy lifestyle. CLIs are most often delivered through face-to-face sessions with limited use of eHealth technologies. To integrate eHealth into existing CLIs, it is important to identify how behavior change techniques are being used by health professionals in the online and offline treatment of overweight clients. Therefore, we conducted online semi-structured interviews with providers of online and offline lifestyle interventions. Data were analyzed using an inductive thematic approach. Thirty-eight professionals with (n = 23) and without (n = 15) eHealth experience were interviewed. Professionals indicate that goal setting and action planning, providing feedback and monitoring, facilitating social support, and shaping knowledge are of high value to improve physical activity and eating behaviors. These findings suggest that it may be beneficial to use monitoring devices combined with video consultations to provide just-in-time feedback based on the client’s actual performance. In addition, it can be useful to incorporate specific social support functions allowing CLI clients to interact with each other. Lastly, our results indicate that online modules can be used to enhance knowledge about health consequences of unhealthy behavior in clients with weight-related health risks.

A Calibration of the Solar Load Ratio Method to Determine the Heat Gain in PV-Trombe Walls

The Trombe wall is a passive system used in buildings that indirectly transfers thermal energy to the adjacent environment by radiation and convection, and directly by the thermo-circulation that arises in the air cavity delimited between a transparent and an absorbing surface. Nevertheless, the latter is painted black to increase the energy gains, but this produces a negative visual impact and promotes the overheating risk in summer. To mitigate these aspects, a hybrid Trombe wall equipped with PV panels can be employed. The PV installation results in a more pleasing wall appearance and the overheating risk reduces because part of the absorbed solar radiation is transformed into electricity. To determine the actual performance of a such system, transient simulation tools are required to consider properly the wall thermal storage features, variation of the optical properties, air thermo-circulation, and PV power production. Alternatively, regarding the traditional Trombe wall, the literature provides a simplified empirical method based on the dimensionless parameter solar load ratio (SLR) that allows for preliminary evaluations and design. In this paper, the SLR method was calibrated to determine the monthly auxiliary energy to be supplied in buildings equipped with PV-Trombe walls in heating applications. The SLR method was tuned by a multiple linear regression by data provided by TRNSYS simulation that allowed to obtain the energy performances in actual conditions of PV-Trombe walls installed on the same building but located in different localities. The comparison between the TRNSYS results and the calibrated SLR method determined average errors ranging between 0.7% and 1.4%, demonstrating the validity of the proposed methodology.

Contemporary Populist Representation and Its Implications for Democracy

This chapter aims to shed light on the connections between populism, democracy, and democratic theory by providing a theoretical assessment of contemporary populism and populist representation as an alternative form of political representation to party government or as a corrective of it. The chapter summarizes the conceptual background relating to democracies, populism, and contextual surroundings. Then, it proceeds to investigate how they relate to each other in present-day politics. The author argues that populism is a strategic political style that exploits the gap between the promise and the actual performance of democracies thus reflects on democratic reality. Hence, it embodies what realist democratic theory has argued for quite some time now about the nature of politics. Namely: voters are irrational, our notions of democracy are delusional and populist politicians seem to have realized it first..

Constructing Indicators For Islamic Financial Inclusion

This study conceptualizes and proposes the measurement items and constructs for assessing the financial inclusion of Islamic finance. It proposes and validates the demand-side measurement tool for the financial inclusion of Islamic finance using four dimensions, i.e., quality, accessibility, usage, and satisfaction. The measurement instrument proposed in this study assesses the actual performance of Islamic finance towards total financial inclusion. The study was based on exploratory factor analysis of the questionnaire responses collected from 129 respondents. The questionnaires were distributed to the Zanzibar residents from February 2021 to March 2021. The questionnaires are adapted mainly from the Findex Survey (2017). The financial inclusion of Islamic finance can be determined using four dimensions (components); relevancy (quality) of Islamic financial services, accessibility of Islamic financial services, usage of Islamic financial services, and satisfaction with Islamic financial services. The study is limited to Principal Components Analysis as a factor analysis approach. Besides, the study has been conducted in Zanzibar, a semi-autonomous nation in East Africa. Therefore, more comprehensive studies are required in various areas for generalizing the results.

Changes in Quality of Economic Planning in the Late USSR: Technological and Institutional Dynamics

Introduction. Studying the Soviet economic performance is important in searching for arguments in the ongoing debate on the possibilities of routine and strategic planning application for economic development of the Russian Federation. The purpose of the article is to identify the dynamics of the planning quality of the Soviet economy in the framework of the institutional approach to economic history. Materials and Methods. The author constructed a data set filled with available information on key growth indicators (national income, production volume and labor productivity, capital investment) targeted in five-year and annual plans, which passed their way from initial drafts proposed by academic economists and employees of the State Planning Commission to approved legal documents, and to the further implementation, presented in branch (industry, agriculture, retail) and spatial (union republics) breakdown. The archival data on the growing activity of the State Planning Commission for revising the approved planned indicators is of our primary contribution. Results. The author highlights the factors underlying the deviations for key planned aggregated indicators that arose at various stages of their preparation, adoption and revision, between their approved figures and actual performance. The results of the data analysis basically confirmed our hypothesis that the technological improvement of the planning process was largely offset by the deterioration of institutional interactions between its subjects. Discussion and Conclusion. While there were signs of an increase in the role of scientists in the process of drafting five-year plans from the second half of the 1950s to the mid-1970s, then from the second half of the 1970s we find less and less evidence that they played a meaningful role in the short and medium term planning processes. On the other hand, our analysis revealed a significantly higher level of fulfillment in annual breakdown compared to five-year one. This confirms the view that just annual plans performed more operational functions, as compared to the motivational ones, in managing the Soviet economy.

Modelling of Auxetic Woven Structures for Composite Reinforcement

The current research is focused on the design and development of auxetic woven structures. Finite element analysis based on computational modeling and prediction of axial strain as well as Poisson’s ratio was carried out. Further, an analytical model was used to calculate the same parameters by a foldable zig-zag geometry. In the analytical model, Poisson’s ratio is based on the crimp percentage, bending modulus, yarn spacing, and coefficient of friction. In this yarn, properties and fabric parameters were also considered. Experimental samples were evaluated for the actual performance of the defined auxetic material. Auxetic fabric was developed with foldable strips created in a zig-zag way in the vertical (warp) direction. It is based on the principle that when the fabric is stretched, the unfolding of the folds takes place, leading to an increase in transverse dimensions. Both the analytical and computational models gave close predictions to the experimental results. The fabric with foldable strips created in a zig-zag way in the vertical (warp) direction produced negative Poisson’s ratio (NPR), up to 8.7% of axial strain, and a maximum Poisson’s ratio of −0.41 produced at an axial strain of around 1%. The error percentage in the analytical model was 37.14% for the experimental results. The computational results also predict the Poisson’s ratio with an error percentage of 22.26%. Such predictions are useful for estimating the performance of auxetic woven structures in composite reinforcement. The auxetic structure exhibits remarkable stress-strain behavior in the longitudinal as well as transverse directions. This performance is useful for energy absorption in composite reinforcement.