Rectangular Room Research Articles

Counting The Number of Arrangements of Tatami Mats in a Rectangular Room of Vertical Length 2, 3 and 4

Counting The Number of Arrangements of Tatami Mats in a Rectangular Room of Vertical Length 2, 3 and 4

Enhancing indoor temperature mapping: High-resolution insights through deep learning and computational fluid dynamics

This paper examines the temperature distribution in a closed, rectangular room equipped with an air conditioning system, employing a computational fluid dynamics model to simulate a virtual thermal camera that captures detailed temperature snapshots. A super-resolution framework enhances the postprocessing of these results. Specifically, convolutional neural networks, trained on simulation data, are used to accurately model temperature fields' high-resolution spatial and temporal evolution. The model demonstrates strong performance by accurately reconstructing temperature profiles from low-resolution inputs obtained from filtering data obtained using high-resolution numerical simulations, with quantitative metrics indicating acceptable accuracy for resolutions reduced by up to 50 times. This effectively aligns with ground truth profiles under various conditions. These results underscore the super-resolution model's potential to transform environmental monitoring in smart buildings and complex structures by generating high-resolution thermal maps from low-resolution cameras or limited sensor input. This approach offers a fast, cost-effective, and reliable method for accurately modeling thermal dynamics within the turbulent flow environments of interior spaces.

PIV Experimental Study of Airflow Structures in a Multi-Slot Ventilation Enclosure with Opposed Jets

The airflow structure of enclosures directly affects the spread of COVID-19 and is also closely related to indoor air quality, the thermal comfort of personnel, and buildings’ energy consumption. A large number of studies on airflow field under mixing and displacement ventilation with a single air inlet in rectangular rooms have been conducted; however, to the best of the authors’ knowledge, only a limited number of studies have dealt with airflow structures in a multi-slot ventilation enclosure with opposed jets. Therefore, this paper uses PIV to study the velocity, turbulence information, and entropy of an unstable airflow field in a multi-slot ventilation enclosure with opposed jets under isothermal and non-isothermal conditions. This paper also presents, due to the collision of the jets to form two large-scale eddies, the airflow field structure being unstable. In the region without air supply inlets and exhaust outlets, a large-scale vortex is formed in the airflow field, resulting in the high information entropy of the flow field. The thermal plume suppresses the large-scale flow field structure and increases the small-scale flow field structure.

Enhancing Visible Light Communication Channel Estimation in Complex 3D Environments: An Open-Source Ray Tracing Simulation Framework

Estimating the optical power distribution in a room in order to assess the performance of a visible light communication (VLC) system is nothing new. It can be estimated using a Monte Carlo optical ray tracing algorithm that sums the contribution of each ray on the reception plane. For now, research has focused on rectangular parallelepipedic rooms with single-textured walls, when studying indoor applications. This article presents a new open-source simulator that answers the case of more complex rooms by analysing them using a 3D STL (stereolithography) model. This paper describes this new tool in detail, with the material used, the software architecture, the ray tracing algorithm, and validates it against the literature and presents new use cases. To the best of our knowledge, this simulator is the only free and open-source ray tracing analysis for complex 3D rooms for VLC research. In particular, this simulator is capable of studying any room shape, such as an octagon or an L-shape. The user has the opportunity to control the number of emitters, their orientation, and especially the number of rays emitted and reflected. The final results are detailed heat maps, enabling the visualization of the optical power distribution across any 3D room. This tool is innovative both visually (using 3D models) and mathematically (estimating the coverage of a VLC system).

Not a Temple but a Tomb: The Architectural Drawings on Pap. Berlin P 15781 and 15782A + B

Summary Based on a reassessment of the papyri Pap. Berlin P 15871 and 1582A+B with the correction of several readings, particularly one of the three determinatives of (i) “shrine”, the key word for their earlier interpretations, it is suggested that the architectural drawings do not show a rock cut temple or a hemi-speos but KV 5, the so-called tomb of the sons of Ramesses II in the Valley of the Kings. Differences in the handwriting, in the depiction of the bedrock pattern surrounding the rectangular rooms, and other observations suggest that more than one person was involved in the creation of the architectural drawings. As suggested in the past, they belonged to at least two different papyri. Terms referring to work in progress indicate that the papyri are related to work in progress, as opposed to other architectural drawings which represent the beginning or final stages of tomb construction projects.

Investigation of sound field diffuseness in an irregularly-shaped room based on FMBEM incidence directivity analysis

Several methods to evaluate sound field diffuseness have been proposed in terms of the isotropy of traveling sound waves. In a previous paper, we investigated the characteristics of two kinds of diffusion indices in a rectangular room, based on the incidence directivity analysis employing the FMBEM. The present study applies the incidence directivity analysis to an irregularly-shaped reverberation room for measurement of sound absorption, and investigates the effects of room shapes and absorbing surfaces on the diffusion indices. The numerical results show that the indices tend to be higher in an irregularly-shaped room than in a rectangular room, and those decline remarkably with increasing the absorption coefficient of the walls. Moreover, the tendencies are more clearly seen in the diffusion indices for the 1/3-octave bands than for single frequencies.

A novel numerical method for solving the Kirchhoff-Helmholtz integral equation based on the sound field representation using the reproducing kernel in the frequency domain

The paper introduces a unique numerical solution method for the Kirchhoff-Helmholtz integral equation. This method is based on the representation of the sound field using the reproducing kernel in the solution space of the homogeneous Helmholtz equation. When compared to the conventional boundary element method, the proposed method holds numerous advantages. This paper presents the analysis theory of the proposed method and demonstrates its validity by calculating bounded and unbounded sound fields. The accuracy of the calculation is assessed by computing the sound field in a rectangular room under various conditions. Furthermore, although some theoretical issues remain, the proposed method effectively avoids the non-uniqueness of solutions in unbounded domain problems.

A tool to calculate the reverberation time of rooms with uneven absorption distribution

The reverberation time in rectangular rooms with uneven distribution of absorbing elements and surfaces, for example suspended ceilings, lead to a non-diffuse sound field. This implies longer reverberation times than predicted by sabines or eyrings reverberation formula. To enable a correct prediction of the reverberation times in such rooms, the only possibility was to apply room acoustic simulations, which require high effort to model the room and to perform the simulation. In 2021, a prediction method was published by Zhou et. al. to calculate the reverberation time in such rooms much more precisely than using sabines or eyrings formula, without the need for a room acoustic simulation. This method has been transformed into an online calculation tool, named "reverberate". In this contribution the methodology will be quickly reviewed and the online tool will be presented.

Gaussian distribution-based randomised image method

Sweeping echo is an acoustical phenomenon present in perfectly rectangular rooms that is characterised by a continuous increase in pitch arising from the concurrent arrival of multiple higher-order reflections. Even though the room acoustic simulation software predicts their presence, in most rectangular rooms sweeping echoes can hardly be perceived due to the existence of small irregularities in the room geometry. In this paper, the image sources' position randomisation model developed within the randomised image method framework with which the incongruence between the original image method results and in situ measurements can successfully be reduced is replaced with a Gaussian distribution model. The results indicate that with the proposed model an improvement in the stability of the room transfer function across realisations can be achieved.

Verification of frequency-dependent impedance boundaries for the Finite-Volume Time-Domain scheme

Numerical simulation methods are widely used to approximate solutions to the wave-equation, taking into account the initial condition ('initial sources') and boundary conditions ('wall materials'). Trustworthy simulations are essential; a primary step is to ensure the correctness of the implementation through a process known as code verification. In this work, we do code verification by studying the convergence of the known finite-volume time-domain (FVTD) method with a frequency-dependent boundary condition modeled as an inductance/resistance/capacitance (LRC) termination. Due to the difficulties of obtaining an analytical solution for frequency-dependent impedance boundaries, we thoroughly derive and implement The Method of Manufactured Solutions tailored to the wave-equation inside a rectangular room for uniform frequency- dependent wall impedance. Asymptotic estimates are found empirically based on a convergence study compared against the manufactured ground truth solution. We investigate the impact of the frequency-dependent boundaries on the convergence affected by the total sum of numerical errors and validate the theoretical properties of the FVTD scheme for various LRC model configurations. The method should also serve as a useful resource for others to verify the correctness of their code implementations.

Influence of scene aspect ratio and depth cues on verticality perception bias.

Perceiving verticality is crucial for accurate spatial orientation. Previous research has revealed that tilted scenes can bias verticality perception. Verticality perception bias can be represented as the sum of multiple periodic functions that play a role in the perception of visual orientation, where the specific factors affecting each periodicity remain uncertain. This study investigated the influence of the width and depth of an indoor scene on each periodic component of the bias. The participants were presented with an indoor scene showing a rectangular checkerboard room (Experiment 1), a rectangular aperture on the wall (Experiment 2), or a rectangular dotted room (Experiment 3), with various aspect ratios. The stimuli were presented with roll orientations ranging from 90° clockwise to 90° counterclockwise. The participants were asked to report their subjective visual vertical (SVV) perceptions. The contributions of 45°, 90°, and 180° periodicities to the SVV error were assessed by the weighted vector sum model. In Experiment 1, the periodic components of the SVV error increased with the aspect ratio. In Experiments 2 and 3, only the 90° component increased with the aspect ratio. These findings suggest that extended transverse surfaces may modulate the periodic components of verticality perception.

The impact of room shape on affective states, heartrate, and creative output

The architectural design of space can deeply impact an individuals' mood, physiology, and mental health. While previous research has predominantly focused on elements like nature and lighting within architectural spaces, there is a growing literature base that also investigates the psychological and neurophysiological impacts of geometrical properties of architectural spaces. Employing virtual reality technology, the study sought to investigate the effects of curved and rectangular architectural spaces on affective states, heart rate, and creativity.A total of 35 participants were exposed to two distinct virtual environments: a curved room and a rectangular room. Participants' self-reported mood was assessed using the Positive and Negative Affect Schedule (PANAS-Long Form). Heart rate was monitored using a pulse oximeter, and creative output was evaluated using the Guilford Alternative Uses Task (GAUT).Statistical comparisons between the two room types indicated that participants experienced higher positive affect and lower negative affect in the curved room condition compared to the rectangular room condition. Furthermore, heart rate measurements revealed lower physiological arousal in the curved room. Additionally, participants exhibited higher creative output in the curved room as opposed to the rectangular room.These findings align with previous literature on the influence of geometric factors on affective responses. The implications of this study are significant as they pertain to individuals' daily environments and their impact on health and well-being. The positive influence of curved room geometry on mood, arousal, and creativity emphasises the importance of considering room layout and design in various settings, such as workplaces and educational environments. Architects and designers can utilise these findings to inform their decisions and promote neuroarchitecture that enhances positive emotional experiences and productivity.

Directional reverberation time and the image source method for rectangular parallelepipedal rooms.

The image source (IS) method is a commonly used geometrical acoustics simulation technique in room and virtual acoustics. In particular, it has been used in the analysis of room reverberation under different choices of geometry and wall conditions. Under a simple rectangular parallelepipedal geometry, reverberation time is known to be dependent on the direction of arrival of reflections relative to the room axes. In this article, a closed-form expression for the directional energy decay and reverberation time is derived, which is valid in the late response, and may be used in the case of either angle-independent or angle-dependent reflection. The expression reduces to an easily evaluated formula in the case of an omnidirectional energy decay curve (EDC). Various numerical results are presented, including the validation of the closed-form expression against EDCs and late reverberation times drawn directly from the IS method.

Measurements of sound absorption coefficients of raked audience seating in a rectangular scale model room

Despite its significance, the sound absorption property of seating has not been fully understood compared to the other surfaces in an auditorium. In particular, the lack of information for sound absorption by seating with changes in section may lead to a failure in accurate prediction of room acoustics. This research investigates the effect of floor rake angle change on the sound absorption property of seating through a series of measurements performed in a rectangular scale model room. Both the sound absorption coefficients (αA) of unoccupied and occupied seating are measured using combinations of three different types of scale model chairs and two different types of scale model auditors while the floor rake angle is systematically varied. The results suggest that the αA’s for both unoccupied and occupied seating significantly increase as the floor rake angle becomes larger. However, the relationship between the floor rake angles and the corresponding αA’s is not monotonous. The effect of changing floor rake is highly associated with the upholstering of chairs for unoccupied seating, whereas it critically depends on the sound absorption property of auditors rather than the upholstering for occupied seating.

Poster Session I: Dissociation of torsional eye movements and perception during optokinetic stimulation by visual cues of gravity.

An optokinetic stimulus rotating about the naso-occipital axis drives torsional eye movements and causes a bias in perception of upright measured with a subjective visual vertical (SVV) task. In addition, a static image with tilted visual cues of gravity orientation will induce optostatic torsion and biases SVV. We posit that a visual gravity cue provided by a frame combined with a torsional optokinetic stimulus would increase measured torsion and further bias SVV. We use a VR headset with eye-tracking to place the subject in a virtual room with circles forming either a rectangular room (frame condition) or a tubular room (no-frame condition). We place a fixation point at the center of the room while the subject performs a SVV task. The room either rotates about the naso-occipital axis at 0.05 Hz, 0.1 Hz, or 0.2 Hz, with an amplitude of ±20°, or has a static tilt of 0° or ±30°. Static frame conditions had the expected bias of SVV and optostatic torsion compared to the control no-frame condition. In sinusoidal rotation conditions, for SVV, there was a significant difference in the amplitude of the response between the frame (5.4 ± 2.6°; mean ± std) and no-frame (3.0 ± 1.3°) condition, while there was no significant difference for torsion, frame (0.8 ± 0.6°) and no-frame (0.7 ± 0.6°). Our results indicate that while perception integrates a moving visual cue into its estimation of upright orientation, the ocular motor system is only affected by those cues when they are static.

Mathematical model of reverberation decay in a rectangular room with uneven distribution of absorption

Based on traditional reverberation theories such as Sabine's or Eyring's theories, the reverberation energy decay becomes linear in logarithmic scale of energy. However, this is valid only in diffuse sound fields. Sound fields in actual rooms are non-diffuse sound field. It has been well known that nonlinear reverberation decay occurs in a rectangular room with uneven distribution of absorption. Hence, reverberation times measured in such rooms are not correspondent with those calculated by the theories. Reverberation theories for such rectangular rooms have been proposed by some researchers. However, these theories have not been sufficiently validated. In this study, a new mathematical model of reverberation decay in rectangular rooms with uneven distributions of absorption is proposed. Most of previous theories contained only exponential decays. The proposed model in this study contains not only exponential decays, but also power law decays.

FMBEM simulation of the laboratory measurement of sound transmission loss in rectangular test rooms

In order to predict sound transmission loss of building elements, the fast multipole boundary element method is applied to simulate the laboratory measurement method in rectangular test rooms specified by ISO 10140-2 (JIS A 1416) for all the frequency bands from 100 to 4 kHz. Firstly, fine and simplified models are validated in comparison with theoretical and measured results for reference samples of membrane materials. Secondly, in addition to the sound pressure method, the sound intensity method is numerically simulated. As a result, it was shown that both models are applicable at mid and high frequency bands, but a simplified model overestimates the transmission loss more than a fine model at low frequency bands. Regarding the sound intensity method, the simulated values are lower than those with the sound pressure method, however approaching the theoretical values.

Prediction of room acoustic parameters in rectangular rooms using recurrent neural networks

Reliably and efficiently predicting room acoustic parameters in rectangular rooms with an uneven distribution of materials and sound absorption is a common task in room acoustic design. Readily available statistical formulas are often not applicable to typical classrooms, cellular offices, or hospital wards. Furthermore, many of these methods only predict the reverberation time, each with their own, often ambiguous limitations of applicability which is impractical for an efficient room acoustic design process. On the other hand, predicting room acoustic parameters by means of ray-tracing or other numerical methods might not be economically feasible for a large number of spaces in many development projects. In this paper, we present a deep learning framework and results based on a sequence processing recurrent neural network to predict several room acoustic parameters. The deep learning models yield prediction speed improvements over ray-tracing or numerical methods, and also significantly improve accuracy over traditional statistical estimation formulas for rectangular rooms. We present the implementation of the method in the soundy.ai application.

Relation between sound absorption and speech intelligibility in room, part 2: Case study based on geometric simulation

Sound absorption works for reverberation suppression and noise reduction, both of which contribute to improving speech transmission performance. In the previous paper, its combined effect was theoretically investigated to clarify the relationship among of reverberation time, average absorption coefficient and speech intelligibility indices. In this paper, a case study is first conducted to examine the applicability of the theoretical estimation of clarity C50 based on geometric simulation. In rectangular rooms with different volumes, aspect ratios and absorption distributions, impulse responses are simulated for various source-to-receiver positions, and then the distributions of the simulated C50 are compared with the theoretical values. Furthermore, a subjective experiment on speech intelligibility is conducted by using a 6-channel sound field reproduction system, where a speech signal is convolved with the simulated impulse responses under background noise conditions. The results show the correlation between the listening difficulty rating and the estimated useful-to-detrimental ratio U50.

Determination of sound-field diffusion indices based on FMBEM incidence directivity analysis

Regarding the diffuseness of sound field, several indices and their measurement methods have been proposed in terms of isotropy of traveling waves. In this paper, we attempt to calculate two kinds of diffusion indices based on the incidence directivity analysis employing the fast multipole boundary element method (FMBEM). The directivity analysis is performed for steady-state sound fields in a rectangular room with changing the absorption condition of the walls. As for diffusion indices, the directional diffusion coefficient is determined from the deviation of directivity of sound intensity, while alternative isotropy indicator is calculated through the spherical expansion of the directivity. The numerical results show general tendencies that the former index is almost constant, whereas the latter index decreases with increasing the frequency. As a common tendency, it is confirmed that the indices become higher in a reflective room condition, and remarkable dips occur around the natural frequencies when absorbing walls are unevenly distributed. Moreover, concerning the receiving cell, the size of it has little effect on the indices. On the other hand, it is verified that the indices become higher with the receiving cell near the point source.