Random Incidence Research Articles

D e ME t RIS: Counting (near)-Cliques by Crawling

We study the problem of approximately counting cliques and near cliques in a graph, where the access to the graph is only available through crawling its vertices. This model has been introduced recently to capture real-life scenarios in which the entire graph is too massive to be stored as a whole or be scanned entirely. Sampling vertices independently is non-trivial in this model, thus algorithms which rely on sampling often use a random walk. The goal is to provide an accurate estimate by seeing only a small portion of the graph. This model is known as the random walk model or the neighborhood query model. We introduce D e ME t RIS: Dense Motif Estimation through Random Incident Sampling. This method provides a scalable algorithm for clique and near clique counting in the random walk model. We prove the correctness of our algorithm through rigorous mathematical analysis and extensive experiments. Both our theoretical results and our experiments show that D e ME t RIS obtains a high precision estimation by only crawling a sub-linear portion on vertices. Therefore, we demonstrate a significant improvement over previous known results.

Random incidence absorption characteristics and parameterized design of micro-perforated panel absorbers with parallel-arranged backing cavities at different depths

Micro-perforated panel absorbers (MPAs) are recognized as efficient and environmentally friendly materials for sound absorption, prompting significant research efforts to expand their frequency ranges. This study investigates the acoustic performance of MPAs with parallel-arranged backing cavities at different depths (PCD) under random incidence conditions. Initially, an analytical model is proposed to predict the acoustic performance of PCD-MPA. The model exhibits significant consistency with finite element simulations and experimental measurements, validating its reliability in calculating absorption coefficients within the primary frequency band of concern (500~4000 Hz) in architectural acoustics applications. Subsequently, a thorough discussion of the key parameters, including the depth sequence and perforation parameters, which influence the random incidence absorption characteristics of PCD-MPA is presented based on the proposed model. These discussions lead to the development of an enhanced parameterized design method aimed at improving the absorption performance of PCD-MPA, enabling precise modulation of parameter combinations to meet specific application requirements and design nearly perfect absorbers.

Estimation of random incidence sound transmission loss of panels based on normal incidence sound transmission loss measurements

The performance of building sound insulation is an important parameter for evaluating the quality of construction projects. So far, the sound insulation performance testing of building walls requires the installation of large-dimensioned wall samples in specialized sound insulation laboratories, which is time-consuming and costly. If small-dimensioned components of the wall panels can be applied and quickly tested at the project site, it could significantly improve efficiency and reduce costs. To address this issue, this paper investigates a method for estimating the random incidence sound transmission loss of wall panels based on the measurement of the normal incidence sound transmission loss of corresponding small samples. Initially, the sound transmission loss of single-layer and composite structures is theoretically analyzed based on the theories of Equivalent Single Layer method and Layer-Wise method. Subsequently, the random incidence sound transmission loss is estimated by the normal incidence sound transmission loss. The methodology for estimating the random incidence sound transmission loss of wall panels proposed in this study offers both a practical approach and theoretical support for the rapid assessment of the sound insulation performance of building walls. This study is of great significance for improving the quality of construction projects and inspection efficiency.

Sound transmission loss of constrained layer damping composites featuring elastic plates embedded with acoustic black hole

This paper preliminarily investigates the influence of an elastic layer with an acoustic black hole (ABH) on the airborne sound insulation of a constrained layer damping (CLD) composite plate. ABHs represent a continuous impedance reduction in a local area of the structure, achieved by reducing material thickness. They efficiently dampen structure-borne sound in plate-like structures, resulting in excellent airborne sound attenuation performance. In the CLD composite structure, a damping layer is inserted between the elastic layers. This configuration achieves noise reduction and provides excellent airborne sound attenuation performance. By incorporating an ABH on one side of the elastic layer within the constrained damping composite structure and utilizing the damping layer as the terminal damping material for ABH, we achieve a lightweight structure with outstanding airborne sound insulation performance. Using finite element numerical calculations, we assess the airborne sound transmission loss of ABHs embedded within the CLD plate. Our analysis compares their transmission losses within the frequency range of 10 to 4000 Hz under normal-incidence and random incidence acoustic field excitations. While the ABH does not enhance the overall sound isolation performance of the CLD plate, it significantly improves the sound isolation dip at the resonance frequency.

Behavioral insights on individual and social adaptation to automated mobility using a serious game

IntroductionSerious games generate a virtual environment where players are immersed in simulated conflicts, guided by distinct rules. They replicate intricate systems, like transportation, encouraging social engagement via reinforced learning. Unlike preference-based studies, these games offer enhanced real-time feedback on players' actions. Thus, they reveal how user experience and social interaction influence decision-making over time. We use a serious game to study the willingness of travelers to adopt automated mobility, specifically shared modes of transport, an important step toward alleviating congestion, enhancing the quality of urban living, and improving people's health and well-being. MethodsFor each scenario, 100 participants were randomly divided into ten groups of ten interacting players. They chose independently out of three automated transportation modes - shared ride, shared car, and automated transit-over 50 simulated days how to commute to work. They aimed to maximize their overall score by arriving punctually, which was influenced by their mode and departure time and the choices of fellow players. Cross-nested logit kernel choice models were estimated based on the game data. ResultsIn the recurring congestion scenario players learned to adopt the shared ride at the expense of transit; in the nonrecurring congestion scenario, random incidents increased the use of transit and shared car (ride alone). ConclusionsCongested traffic motivated a shift to ridesharing at the expense of private rides and public transport; however, the latter was highly demanded when traffic became unsmooth and travel times more uncertain. The implications can be translated to health promoting polices to encourage sustainable travel behaviors while also improving transportation efficiency.

SOUND ABSORPTION COEFFICIENT MEASUREMENT METHODS IN REVERBERATION ROOM AND IMPEDANCE TUBE

Sound absorption materials are very often used for space design in order to reduce the noise level and adjust the acoustic characteristics of the space depending on its purpose. Therefore, knowledge of the acoustic quantities that characterize sound absorption materials is of crucial importance. The most commonly used acoustic quantity is the sound absorption coefficient, which can be determined using standardized methods and methods used only for research purposes. This paper will provide an overview of the most commonly used standardized methods for determining the sound absorption coefficient: the reverberation room method and the impedance tube method. Since the impedance tube method, which provides the normal incidence sound absorption coefficient, is more suitable when developing new absorption materials, and in practical applications, it is desirable to know the random incidence sound absorption coefficient, this paper discusses approaches for predicting the random incidence sound absorption coefficient based on the acoustic parameters of the sound absorption materials measured in an impedance tube.

Interpretation of results of PCR and B-D-glucan for the diagnosis of Pneumocystis Jirovecii Pneumonia in immunocompromised adults with acute respiratory failure

BackgroundThe accuracy of a diagnostic test depends on its intrinsic characteristics and the disease incidence. This study aims to depict post-test probability of Pneumocystis pneumonia (PJP), according to results of PCR and Beta-D-Glucan (BDG) tests in patients with acute respiratory failure (ARF).Materials and methodsDiagnostic performance of PCR and BDG was extracted from literature. Incidence of Pneumocystis pneumonia was assessed in a dataset of 2243 non-HIV immunocompromised patients with ARF. Incidence of Pneumocystis pneumonia was simulated assuming a normal distribution in 5000 random incidence samples. Post-test probability was assessed using Bayes theorem.ResultsIncidence of PJP in non-HIV ARF patients was 4.1% (95%CI 3.3-5). Supervised classification identified 4 subgroups of interest with incidence ranging from 2.0% (No ground glass opacities; 95%CI 1.4–2.8) to 20.2% (hematopoietic cell transplantation, ground glass opacities and no PJP prophylaxis; 95%CI 14.1–27.7). In the overall population, positive post-test probability was 32.9% (95%CI 31.1–34.8) and 22.8% (95%CI 21.5–24.3) for PCR and BDG, respectively. Negative post-test probability of being infected was 0.10% (95%CI 0.09–0.11) and 0.23% (95%CI 0.21–0.25) for PCR and BDG, respectively. In the highest risk subgroup, positive predictive value was 74.5% (95%CI 72.0-76.7) and 63.8% (95%CI 60.8–65.8) for PCR and BDG, respectively.ConclusionAlthough both tests yield a high intrinsic performance, the low incidence of PJP in this cohort resulted in a low positive post-test probability. We propose a method to illustrate pre and post-test probability relationship that may improve clinician perception of diagnostic test performance according to disease incidence in predefined clinical settings.

Spatiotemporal Variations in Co-Occurrence Patterns of Planktonic Prokaryotic Microorganisms along the Yangtze River.

Bacteria and archaea are foundational life forms on Earth and play crucial roles in the development of our planet's biological hierarchy. Their interactions influence various aspects of life, including eukaryotic cell biology, molecular biology, and ecological dynamics. However, the coexistence network patterns of these microorganisms within natural river ecosystems, vital for nutrient cycling and environmental health, are not well understood. To address this knowledge gap, we systematically explored the non-random coexistence patterns of planktonic bacteria and archaea in the 6000-km stretch of the Yangtze River by using high-throughput sequencing technology. By analyzing the O/R ratio, representing the divergence between observed (O%) and random (R%) co-existence incidences, and the module composition, we found a preference of both bacteria and archaea for intradomain associations over interdomain associations. Seasons notably influenced the co-existence of bacteria and archaea, and archaea played a more crucial role in spring as evidenced by their predominant presence of interphyla co-existence and more species as keystone ones. The autumn network was characterized by a higher node or edge number, greater graph density, node degree, degree centralization, and nearest neighbor degree, indicating a more complex and interconnected structure. Landforms markedly affected microbial associations, with more complex networks and more core species found in plain and non-source areas. Distance-decay analysis suggested the importance of geographical distance in shaping bacteria and archaea co-existence patterns (more pronounced in spring). Natural, nutrient, and metal factors, including water temperature, NH4+-N, Fe, Al, and Ni were identified as crucial determinants shaping the co-occurrence patterns. Overall, these findings revealed the dynamics of prokaryotic taxa coexistence patterns in response to varying environmental conditions and further contributed to a broader understanding of microbial ecology in freshwater biogeochemical cycling.

Random incidence sound absorption of micro-perforated panel absorbers backed with parallel-arranged cavities of different depths

This study investigates sound absorption performance of a kind of wideband micro-perforated panel (MPP) absorbers with parallel-arranged backing cavities at different depths in a diffuse field. An analytical prediction model is presented for evaluating the random incidence absorption coefficient of this type of absorbers, and it exhibits excellent agreement with finite element model and experimental measurements. Then, numerical cases were established using this model to investigate the absorption characteristics of this type of absorbers under random incidence, considering the influence of cavity depths and MPP parameters. Results show that the cavity depth and MPP perforation diameter in this absorber are primary influencing parameters controlling the overall sound absorption performance. Cavities at different depths introduce multiple resonant absorption peaks, while the perforation diameter determines matching conditions between the MPP and air impedance, which simultaneously broaden the absorption bandwidth of this MPP absorber. Although individually adjusting the panel thickness and perforation rate has a smaller impact compared to the perforation diameter, the interaction between these two parameters has significant influences across the entire absorption frequency band.

Numerical Equivalent Acoustic Material for Air-Filled Porous Absorption Simulations in Finite Different Time Domain Methods: Design and Comparison

Extracting the microscopic parameters of a porous material is a complex task, and attempts have been made to develop models that can simulate their characteristics, gathering the least amount of information possible. As a case in point, tests to evaluate macroscopic behaviors such as tortuosity, which depends directly on the microscopic fluid velocities, are highly susceptible to generate errors if the precision of the measurement devices is not correct, and the same goes for the other parameters. For this reason, in this paper, a sound propagation model in porous materials with a rigid frame is presented based on a local theory, which tries to simplify, even more, the way to obtain the basic characteristics of porous materials, such as their absorption coefficient at normal and random incidence, and their normal surface impedance. The proposed linearized equivalent fluid model presents four phenomenological coefficients, which characterize acoustic propagation trough the material. Their values are obtained from the material thickness and a measurement in an impedance tube following the ISO 10534 standard. Thus, what is only required is the measured absorption coefficient, either on one third or one octave bands, to fully represent the acoustic behavior in the finite different in time domain (FDTD) method. The model has been simulated with FDTD in porous and fibrous kernels, and the results show a strong agreement with the laboratory measurements and with the analytical results calculated with well-established semi-phenomenological models.

Using Sabine’s and sound power relation to study: The effect of diffusers on measured sound absorption

The purpose of this study is to evaluate the effect of the number of diffusers placed in the same room, as well as the effect of diffusers with a flat area (8.4, 13.2, and 18 m2) on the calculated sound absorption coefficient in a reverberation room, when an iterative procedure based on the evaluation of the sound power level is applied (this is done by using the sound power equation and substituting with different values of equivalent absorption area on both sides of the transformed equation to reach the correct value for absorption area, which achieves equality on both sides of the equation in order to achieve the goal). The sound absorption coefficient at random incident of three materials having different degrees of absorption—has been measured in a reverberation room according to ISO 345: a highly absorbent material (sponge) a medium absorbent material (rubber) and a low absorbent material (wood).There is a noticeable convergence between the calculated and measured sound absorption coefficient from the usual ISO 354 procedure and from the sound power level equation from ISO 3741,when diffusers are present. The difference in sound power level is close to 1.0 dB depending on the position of the source with the diffuser area. Thanks to the diffusers effect, the difference between the measured and the calculated sound absorption coefficient can be considerably reduced.

Measuring directivity of half-inch measurement microphones

The directivity of a microphone is the relative sensitivity variation as a function of incidence angle. This is an important characteristic when every sound arriving at the microphone position is relevant. This paper presents the measuring directivity of half-inch measurement microphones. The microphone is placed in a free sound field and exposed to a sound pressure. The unloaded output voltage is measured. Then, the microphone is rotated in 30o steps, while both the acoustic centers of the microphone and the sound source remain in fixed positions in the sound field, and is exposed to the same sound pressure. The unloaded output voltage for each angle of incidence is measured and them the difference relative to 0 deg. of incidence is calculated as a function of frequency. The directivity of eight measurement microphones from the same manufacturer but of different types and frequency response characteristics (i.e. pressure field, random incidence or free-field) were measured. Results showed that the microphones object of this investigation have similar directivities in the frequency range from 16 Hz to 12.5 kHz regardless of their frequency response characteristics.

Diffusion equation-based modelling of reverberation chambers for sound absorption measurements

Recent research in reverberation chambers has revealed unacceptably large variations resulting from round-robin tests of the standardized measurements of random-incidence absorption coefficients. These variations have prompted active research activities in architectural acoustics. This study applies a diffusion equation model (DEM) in acoustics of reverberation chambers for random incidence absorption measurements by predicting both reverberant sound energies and energy flows. The DEM is of high computational efficiency when compared with other existing geometrical acoustics and wave-based methods. The DEM modeling of the sound energy flows in a reverberation room further reveals violations of the diffuse field assumption near the boundary area of absorbing sample under test. Due to its computational efficiency and higher order of the reverberant energy prediction of the statistical room-acoustic modeling, this work investigates an estimation approach to the absorption coefficients of the sample under test. The proposed approach estimates the absorption coefficients by pursuing both the DEM simulations and the chamber-based measurements. This paper investigates sound energy flux over varied absorbing degrees of absorber samples in standardized sizes, computational efficiency of the DEM for reverberant energy decays in reverberation chambers, and potential significance applied to random-incident absorption coefficient measurements.

Sound Absorption and Material Properties of Asphalt Rubber Concrete Specimens

The acoustic and material properties of asphalt crumb rubber (ARC) pavement have been measured and correlated. Laboratory measurements revealed nonlinear relationships between the sound absorption coefficients and material properties of compacted specimens as a function of the percentage of crumb rubber content in conventional and modified binders. The acoustic performance of conventional asphalt and asphalt rubber concrete specimens are compared to their material properties as a function of crumb rubber content to determine how crumb rubber content influences sound absorption. The normal incidence sound absorption coefficients, porosity, percentage of voids in mineral aggregate, and absolute gas permeability are measured for specimens containing 0, 5, 10, 15, and 20% crumb rubber in the asphalt binder. The random incidence sound absorption coefficient and material property data share nonlinear distributions within some frequency ranges, as a function of crumb rubber content in the conventional and modified asphalt binders.

Estimation of the random incidence sound absorption coefficients of different size rectangular samples.

The sound absorption coefficient (SAC) of materials measured in a reverberation room is affected by both the intrinsic properties of the material and geometrical dimensions of the sample. A different size of the same material may produce a different SAC primarily due to the edge effect phenomenon. In this research, the experimental data from multiple laboratories was analyzed to evaluate the influence of the edge effect. An empirical function was established based on these measurement data and the linear relationship between the SAC and the relative edge length. Thomasson's method, the two geometric methods, and the analytical method were used to estimate the SAC of an absorber from measurements on a different size sample and compared with results obtained using the empirical function. The results show that the proposed empirical method is a reliable way to predict the SAC of a sample from measurements on a different size sample of the same material, which only requires the thickness, density, and size of the material.

Sustainable Perforated Acoustic Wooden Panels Designed Using Third-Degree-of-Freedom Bezier Curves with Broadband Sound Absorption Coefficients.

The current interior design scope places high demands on acoustic treatment manufacturers. The state of the art does not provide satisfactory material proposals for architects to satisfy design needs. There is a need for a novel approach concerning decorative, recognized materials that adapts them to the acoustic surface properties. The final design proposed in this study presents a modern functional solution with high acoustic properties, which can be produced with sustainable materials such as FSC wood and has a low environmental impact because of its low waste production. This research presents the complete design process of a novel type of wooden acoustic panel. A comprehensive explanation of the scientific development is covered, including basic material testing in an impedance tube, FEM simulations of the initial designs, and final measurements in a reverberation chamber. The solution's novelty is based on the optimized placement of the perforation holes on the surface of a wooden overlay using a ship deck optimization algorithm. The methods used cover the original solution of mixing FEM modeling of the surface impedance with the application of the Jeong-Thomasson correction for random incidence sound absorption coefficient simulation. The contribution of this research is the development of wooden perforated panels with Class A sound absorption and an overall depth of 90 mm, including the 50 mm depth of the backing material. The discussion will explain the difficulties of working with this material and the need for a combination of the aesthetic and acoustic sides of the project.

396 Systematic Review and Meta-Analysis of Studies Comparing the Rate of Post Operative Periprosthetic Fracture Following Hip Arthroplasty with a Polished Taper Slip Versus Composite Beam Stem

Abstract Aim To compare the incidence of post-operative periprosthetic femoral fractures (POPFF) following hip replacement with either a cemented polished taper stem (PTS) or cemented composite beam stem (CB) in comparative studies. Method A systematic review of comparative studies, written in English, and published in peer-reviewed journals since year 2000 to 2021 was conducted using Ovid MEDLINE, EMBASE, Web of Science, and Scopus. Methodology followed the Preferred Reporting items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Study quality was assessed using the Newcastle-Ottawa scale. Cohorts were classified as high or low risk of POPFF based on patient risk factors. Metanalysis was performed using a random effects model and relative incidence with 95% confidence intervals were reported. Results The overall study quality was good. 913,021 patients from 18 cohorts were included in the meta-analysis. 294,540 patients received a CB stem and 618,481 received a PTS stem. For patients at low risk of POPFF the incidence rate ratio (IRR) was 3.14 (CI: 2.48, 3.98) for the PTS group versus CB group. For patients at high risk of POPFF the IRR of 9.87 (CI: 3.63, 26.80) for the PTS group versus the CB group. Conclusions The risk of POPFF is lower when hip arthroplasty was performed using a composite beam stem versus a polished taper slip stem. This protective effect was greatest in patients with a higher risk of POPFF. Surgeons should consider the effect of cemented stem choice on risk of subsequent periprosthetic femur fracture, particularly in frail or elderly patients at risk of periprosthetic femoral fracture.

Method for Calculating the Sound Absorption Coefficient for a Variable Range of Incidence Angles

The theoretical estimation of sound absorption coefficient of a surface may give very different results. This will depend on the type of sound field assumed in the theoretical model used for the estimation of its sound absorption coefficient. Absorption coefficients for normal and diffuse sound fields are widely known, although they may be far from the absorption values given by an absorbing material when it is finally installed inside a room or enclosed space, where a sound field closer to a spherical wavefront is more likely to be found. This work presents a theoretical study, which is addressed at obtaining a mathematical expression to calculate the sound absorption coefficient for a variable range of incidence angles, called $α_s$. The presented method uses a circular sound field incidence as an approximation to a spherical incidence. The estimation of this coefficient $α_s$ is based on obtaining the incident and reflected sound fields for a surface located facing a lineal source. The advantage of this calculation method over others lies on its capability to give results for circular, normal and random wave incidence depending on the range of incidence angles considered in the calculation.

Polarization Detection of Terahertz Waves using All‐Silicon Metasurfaces with Tightly Focusing Behavior

AbstractThe manipulation of polarization states is reflected in the tailoring of light–matter interactions and has great applications in fundamental science. Nevertheless, the conventional polarization‐separated detection behavior in the terahertz (THz) band is very challenging when applied to visualize the incident polarization state since its measurement requires sophisticated instrumentation. Here, the feasibility of its reconstruction of the full‐Stokes parameter matrix in the THz band is explored by establishing an all‐silicon decoupled metasurface based on the polarization multiplexing encoding technique. The pixelated focal spots gathered in the target plane allow us to employ more elaborate methods to extract the characteristic parameters of the incident polarization states. The resolvability of the THz polarization detection behavior with a single focal spot is further optimized benefiting from the longitudinal polarization component (Ez) generated by the tightly focused beam in the propagation direction. The capability of the Ez‐component in determining the key parameters that compose the polarization ellipse is evaluated by predefining the random incident polarization on a standard Poincaré sphere. Thus, the proposed scheme offers significant advantages in future THz communications, providing opportunities for ultra‐compact, high‐resolution full‐Stokes polarization imaging and multidimensional information processing.

Resilience-Mechanism-Based Dynamic Resource Allocation in Dispersed Computing Network

When degradation occurs in a dispersed computing network, mitigating the persistent effects of failures and improving the disposal efficiency is an open problem. However, the occurrence of failed nodes in a dispersed computing network is a random and low-probability incident. Further, the resilient resources for emergency allocation are from devices with complex spatial locations in practice. These factors pose challenges to the resource allocation problem using resilience mechanisms. In this article, we explore and analyze a resilience mechanism for dispersed computing networks as an optimization model. We investigate a resilience-aware dynamic resource allocation model to cope with a degraded dispersed computing network and obtain better emergency response at a lower cost. The uncertainties of node failures are uniquely explored to capture failure nodes more precisely and initiate the resilience mechanism for such nodes. In addition, we propose a novel approach to deal with the dynamic and complex coupling characteristics of decision variables in the model. This approach incorporates the induced artificial fish swarm algorithm with dynamic system simulation to generate and improve the scheme for the allocation of resilient resources. Finally, numerical simulation results verify the improved performance of our model and the effectiveness of the algorithm.