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This study investigates aluminum heat sinks integrated with GR42 phase change material (PCM), aiming to enhance thermal inertia and stabilize device temperatures. This is important, since the increasing miniaturization and performance demands for electronic devices have led in a growing need for advanced thermal management systems capable of handling rapid transient loads. The novelty of the work lies in examining different heat sink layouts that optimize the heat dissipation capabilities of GR42 PCMs while minimizing size and weight for electronic cooling. The experimental testing was conducted using three configurations, namely no fin, circular fin and hexagonal fin, with three input powers (4 W, 8 W, and 12 W). The experimental results show that the hexagonal-fin heat sink, surface area is 25 % more than circular fins, exhibited superior thermal performance without significant variation in input power. Notably, the hexagonal-fin heat sink achieved the desired set point temperature of 55 ◦C in 33 % less time than the circular-fin design and 45 % less time than the heat sink without fins. Furthermore, the peak temperatures increased up to 21 % for circular fins. During the charging cycles, the enhancement ratios vary from 72 % and begin to narrow to 25 % during discharge cycles. The hexagonal-fin configuration also exhibited superior melting dynamics, completing the phase transition 44 % faster at higher input power than the circular fins, and established a thermal deviation of nearly 51 % less than finless heat sinks. These findings underscore the critical role of fin geometry and PCM integration in achieving uniform temperature distribution and improved energy storage efficiency. Overall, the hexagonal-fin heat sink with GR42 PCM shows strong potential as a passive cooling solution for low-power portable electronic devices.
A round robin was conducted to evaluate the state of the art of room acoustic modeling software both in the physical and perceptual realms. The test was based on six acoustic scenes highlighting specific acoustic phenomena and for three complex, “real-world” spatial environments. The results demonstrate that most present simulation algorithms generate obvious model errors once the assumptions of geometrical acoustics are no longer met. As a consequence, they are neither able to provide a reliable pattern of early reflections nor do they provide a reliable prediction of room acoustic parameters outside a medium frequency range. In the perceptual domain, the algorithms under test could generate mostly plausible but not authentic auralizations, i.e., the difference between simulated and measured impulse responses of the same scene was always clearly audible. Most relevant for this perceptual difference are deviations in tone color and source position between measurement and simulation, which to a large extent can be traced back to the simplified use of random incidence absorption and scattering coefficients and shortcomings in the simulation of early reflections due to the missing or insufficient modeling of diffraction.
Acoustic musical instruments act as dynamic sound sources communicating the expressive intentions of a performer to the audience in a dedicated spatial environment. From an acoustical point of view, the directivity of musical instruments is relevant both for the loudness and timbre of an instrument at a certain position in the audience, as well as for the spatial characteristics of the generated sound field. Musical instruments, however, are dynamic sound sources always moved by musicians as an element of their performance on stage. This work aims at assessing the acoustical effect and the perceptual relevance of these movements. For this purpose, we have recorded solo musical performances with all standard orchestral instruments with an optical motion tracking system, as well as the corresponding audio signals. The effect of the movements was evaluated by analysing the spectral fluctuation and the time-dependence of room acoustical parameters in a virtual acoustic environment in anechoic and reverberant conditions. In a subsequent listening test, an auralization of the static and dynamic musical performance was presented to listeners by binaural synthesis, showing that the signal-related fluctuations are clearly audible both in anechoic and reverberant situations. We discuss different approaches how to consider these effects for the simulation of natural acoustic sources in virtual acoustic reality.
The motion-tracked binaural (MTB) technique allows the dynamic, pseudobinaural rendering of spatial sound scenes recorded by a circular array of microphones on a rigid sphere. The system provides a multichannel live audio transmission from which a head-related signal with approximated interaural time and level differences can be derived and played via headphones, head tracking, and a corresponding rendering software. The latter is mainly calculating imperceptible interpolation between channel pairs during head movements. This contribution evaluates the potential of this format for the creation of virtual acoustic envi- ronments. Based on the technical realization of a 16-channel MTB array with omnidirectional diffuse field-corrected electret condenser microphone capsules, the plausibility of 8 and 16-channel recordings was tested against a physical sound source. Furthermore, the sound quality of the pseudobinaural rendering was assessed based on different items of the Spatial Audio Quality Inventory (SAQI) compared to a true dynamic binaural reference. The results show that the overall plausibility of the MTB signal with optimal interpolation is close to the reference. Even if there are small differences with respect to tone color and spatial sound source attributes, the degree of externalization and even the perceived source elevation were, despite the absence of pinna cues, well comparable to the true binaural reference.
Unlike electro-acoustic sound sources, musical instruments have a time-varying, dynamic directivity, due to the note-dependent radiation behavior of the instrument and due to the expressive movements that musicians perform with their instrument. While previous studies have generally examined the directivity of the static, unmoved instrument for specific notes played, we show the individual and combined contributions of these two factors to a temporal modulation of the radiation behavior, based on motion tracking of typical movement patterns for all instruments of a classical symphony orchestra and on the directivity measured for all partials over the entire pitch range of these instruments. The effect of this modulation, which is manifested by changes in timbre and room acoustic excitation, was determined by spectral variations in the free field and under reverberant conditions, as well as by a modulation of room acoustic parameters. Our results show that these effects are well above the just noticeable differences for all musical instruments and all perceptual variables considered. While the effect of motion dominates for brass instruments, string and woodwind instruments exhibit large note-related differences, which should be taken into account in virtual acoustic realities if an auditory liveliness comparable to physical reality is to be achieved.
A convincing auralization of acoustical scenes does not only require a proper modeling of the sound propagation between source and receiver, but also an appropriate representation of the acoustical source itself. While the properties of electro-acoustic sources can be well represented by advanced loudspeaker formats with high resolution, the complex, time-variant behavior of natural acoustic sources such as speakers, singers or musical instruments is not in any way considered by current techniques for acoustical simulation and auralization. In the talk, we will present measurement results of the sound power and directivity of natural acoustic sound sources and their dependence on pitch and dynamic level, as well as measurements of typical movements of the source during musical performances. We will demonstrate the physical and perceptual relevance of these effects both in the direct field and in room acoustical environments based on a technical and perceptual evaluation, and discuss new approaches to include these effects in numerical simulations.
With the Room Acoustical Quality Inventory (RAQI), a measuring instrument for the perceptual space of performance venues for music and speech has been developed. First, a focus group with room acoustical experts determined relevant aspects of room acoustical impression in the form of a comprehensive list of 50 uni- and bipolar items in different categories. Then, n = 190 subjects rated their acoustical impression of 35 binaurally simulated rooms from 2 listening positions, with symphonic orchestra, solo trumpet, and dramatic speech as audio content. Subsequent explorative and confirmative factor analyses of the questionnaire data resulted in three possible solutions with four, six, and nine factors of room acoustical impression. The factor solutions, as well as the related RAQI items, were tested in terms of reliability, validity, and several types of measurement invariance, and were cross-validated by a follow-up experiment with a subsample of 46% of the original participants, which provided re-test reliabilities and stability coefficients for all RAQI constructs. The resulting psychometrically evaluated measurement instrument can be used for room quality assessment, acoustical planning, and the further development of room acoustical parameters in order to predict primary acoustical qualities of venues for music and speech.
Automated leaders and followers selection in Stackelberg games for modular manufacturing systems
(2025)
We propose an automated data-driven mechanism to evaluate each actuator’s influence on modular manufacturing system objectives. This mechanism enables automated leader and follower selection in Stackelberg games, which have gained traction in engineering. While leaders typically hold greater priority or influence, systematic methods for assigning leaders and followers remain limited, especially in large-scale applications. As a result, many rely on empirical analysis to assign leaders and followers, without confirming if the selected setup is optimal. Therefore, in this paper, we develop an automated mechanism to evaluate the influence of each player on the global objectives of modular manufacturing systems, applicable to both single- and multi-objective scenarios. We validate the proposed approach within an industrial control scenario, using a modular Bulk Good System and its larger-scale arrangement with sequential and serial-parallel processes. We focus on three objectives, including production flow disruption prevention, power consumption reduction, and production demand fulfilment. Finally, we implement a self-learning algorithm utilizing Modular State-based Stackelberg Games, where leaders and followers are selected using our approach, which leads to encouraging results.
News media coverage mainly focuses on problems and conflicts, resulting in unintended negative consequences for democracy and journalism itself. Constructive journalism aims to address these issues by emphasizing solution-oriented reporting. However, research on its effects remains inconsistent, mainly due to vague definitions of constructive journalism and a lack of theoretical foundation. This paper first proposes a content-centered definition of constructive journalism, suggesting three dimensions: balance, matter-of-factness, and focus on solutions. Using a series of established theories, we then present a theoretical framework that models the impacts of the content dimensions in a chain of effects from emotions to cognitive and conative variables. Our approach offers a systematic basis for future research by enabling experimental analysis of operationalizable and empirically separable content dimensions and by integrating research on constructive journalism into a variety of established media effect theories. Thus, we meet the demand for a stronger theoretical focus and aim to clarify constructive journalism’s impact on audiences.