Transmission Index Research Articles

Sintesis Dimensi Manipulator Paralel Bidang Dua Derajat Kebebasan Dengan Rantai Kinematik Paralelogram Simetris

The paper discussed the process to find the optimum dimension for the kinematic constants of a two-degree of freedom planar parallel manipulator. This manipulator itself was constructed by symmetric three parallelogram chains. An optimization process using non-sorted dominated genetic algorithm II (NSGA-II) was carried out for maximization of ( i ) r MIC (the radius of the maximum inscribed circle) and GCI (global conditioning index), and (ii) r MIC and GTI (global transmission index). Here, GCI and GTI were evaluated on the useful workspace. Instead of using atlases of performance indices, a grid search evaluation was applied to obtain a region in PDS near the optimum values for both maximization cases. This region gave a small bound for NSGA-II to start searching the optimum values of the kinematic constants. For simplification, a python framework for the multi-objective optimization called pymoo was applied to solve the optimization problem. Henceforth, the maximization for two cases yielded an insignificant difference of results in terms of optimum kinematic constants, r MIC , GCI, GTI, area of useful workspace, area of good condition workspace (GCW), area of good transmission workspace (GTW), and the area ratio of GCW and GTW to the useful workspace.

Differential impact of physical distancing strategies on social contacts relevant for the spread of SARS-CoV-2: evidence from a cross-national online survey, March–April 2020

ObjectivesWe investigate changes in social contact patterns following the gradual introduction of non-pharmaceutical interventions and their implications for infection transmission in the early phase of the pandemic.Design, setting and participantsWe...

The soundscape of restaurants part 4 analysis and practical design directions

This paper addresses important sonic issues in restaurants and how they can be addressed from an architectural acoustic perspective. Restaurants have complex sound fields composed of many sound sources, listeners and paths. Some of these sound paths are useful, and others are not. Sound paths from one person speaking to another across a table are typically useful (Near), as diners want to hear each other and converse with those at their table and the waiter. Direct and reflected sound paths that travel from a person speaking to non-intended listeners across the room (Far) are not useful. Speech Transmission Indices were measured for “near” and “far” listeners in restaurants. This idea is illustrated with recent case studies. They are also examined with the C50 metric. It is desirable to have higher near STI and lower far STI, when the background and residual noise levels in the space are considered. This study presents the results along with practical design recommendations on how to improve the STI of near sound paths and reduce the STI of far sound paths, such as spatial separation, part height dividers, strategically placed absorbent material, groupings of tables, subdivision of room, and background music among other strategies.

Acoustic effects of face masks on speech: Impulse response measurements between two binaural mannikins

The COVID-19 pandemic has resulted in widespread use of facial masks that cover the nose and mouth areas to prevent viral transmission. While masks have helped provide protection from spreading illness, they have also had an impact on how people communicate, with many finding it more difficult to understand speech from those who are wearing masks. Facial masks affect the directivity and sound levels of the wearer’s verbal communication, and if opaque, they also cover visual cues that aid understanding. Studies have documented the effect of different mask types on speech intelligibility, speech transmission index, talker directivity, and resulting speech features. This talk presents the first of measurements towards composing a corpus of impulse responses gathered between two head and torso simulators (HATS) in an anechoic chamber at varying directional positions and distances. One HATS with a mouth simulator serves as the talker and is outfitted with different mask types, including cloth, N95, and surgical paper masks, in combination with face shields. The resulting impulse response data base may be used by researchers to simulate masked verbal communication scenarios such as in virtual soundfield environments, allowing systematic testing of how masks impact speech perception in numerous situations.

Acoustic Sensing Analytics Applied to Speech in Reverberation Conditions.

The paper aims to discuss a case study of sensing analytics and technology in acoustics when applied to reverberation conditions. Reverberation is one of the issues that makes speech in indoor spaces challenging to understand. This problem is particularly critical in large spaces with few absorbing or diffusing surfaces. One of the natural remedies to improve speech intelligibility in such conditions may be achieved through speaking slowly. It is possible to use algorithms that reduce the rate of speech (RoS) in real time. Therefore, the study aims to find recommended values of RoS in the context of STI (speech transmission index) in different acoustic environments. In the experiments, speech intelligibility for six impulse responses recorded in spaces with different STIs is investigated using a sentence test (for the Polish language). Fifteen subjects with normal hearing participated in these tests. The results of the analytical analysis enabled us to propose a curve specifying the maximum RoS values translating into understandable speech under given acoustic conditions. This curve can be used in speech processing control technology as well as compressive reverse acoustic sensing.

Blind estimation of speech transmission index and room acoustic parameters based on the extended model of room impulse response

The speech transmission index (STI) and room-acoustic parameters, such as the reverberation time and clarity index, are essential to assess the quality of room acoustics. However, in everyday spaces occupied by people, it is difficult to obtain such parameters since the room impulse response (RIR) cannot be measured. Blind estimation of room acoustic parameters from observed signals without measuring RIR is therefore necessary. Although existing methods can estimate one of these parameters, a single parameter is inadequate to describe comprehensive subjective aspects. To this end, this paper proposes a method for estimating STI and five room-acoustic parameters simultaneously. The temporal amplitude envelope of a reverberant speech signal is mapped to the parameters of an RIR model for each sub-band. Instead of using Schroeder’s RIR model, the extended RIR model is used to approximate an unknown RIR so that the STI and room-acoustic parameters can be derived. We performed simulations to evaluate the proposed method in unseen reverberant environments. The root-mean-square errors between the ground-truths and estimated parameters suggest that the accuracy of the proposed scheme outperformed that with Schroeder’s RIR model and was close to the standard measurements.

Genetic diversity and primary drug resistance transmission in Mycobacterium tuberculosis in southern Mexico

Tuberculosis is a global human health threat, especially in developing countries. The present study aimed to describe the genetic diversity of Mycobacterium tuberculosis and to measure the transmission rates of primary and acquired resistance. A total of 755 M. tuberculosis isolates from a cohort study of patients with culture-confirmed pulmonary tuberculosis in Orizaba, Veracruz, performed between 1995 and 2010 were genotyped by the 24-locus mycobacterial interspersed repetitive unit-variable number of tandem repeats (MIRU-VNTR) method. Drug susceptibility was determined. Logistic regression models were constructed to identify the variables associated with resistance and clusters. The recent transmission index (RTI), the Hunter-Gaston discrimination index (HGDI) for the MIRU-VNTR test and allelic diversity (h) were calculated. The Haarlem and LAM lineages were the most common in the population. A total of 519 isolates were grouped into 128 clusters. The overall drug resistance rate was 19%, isoniazid monoresistance (10%) was the most common, and 3.4% of the isolates were multidrug resistant. Among the 116 isolates resistant to at least one drug, the primary and acquired resistance rates were 81.9% and 18.1%, respectively. Primary resistance was associated with belonging to a cluster (aOR 4.05, 95% CI 1.5-11.2, p = 0.007). Previous treatment history (aOR 9.05, 95% CI 3.6-22.5, p < 0.001) and LAM lineage (aOR 4.25, 95% CI 1.4-12.7, p = 0.010) were associated with multidrug-resistant tuberculosis (MDR-TB). The RTI was 51.7%, and the 24-locus MIRU-VNTR HGDI was 0.98. The alleles with the greatest diversity were 4056-QUB26 (h = 0.84), 2163b-QUB11b (h = 0.79), and 424-Mtub04 (h = 0.72). Primary resistance transmission, high LAM lineage prevalence and its association with MDR-TB represent public health problems. The implementation of molecular tools is needed to improve the existing control surveillance tuberculosis program.

SYSTEMATIC REVIEW ON IMPACT OF MASS DRUG ADMINISTRATION ON LYMPHATIC FILARIASIS PREVENTION

introduction: Lymphatic filariasis (LF) is a disease caused by filarial parasites transmitted to human by mosquitoes and infecting 120 million people worldwide. Mass drug administration (MDA) involves delivering treatment to every person living in a defined geographical area, is the current practice in place and has shown to be very useful in reducing the global transmission of LF. This review aims to explore into the effectiveness of MDA in interrupting the transmission of LF in terms of the types of MDA, number of cycles, coverage, and percentage of transmission reduction. Methods: A systematic search via Scopus, PubMed, and Cochrane was done for articles published from 2015 to 2019 by using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. The articles identified from the databases searched and any that appeared to relate to the research questions were included. A total number of 14 articles fulfilled the criteria for review. Results: Overall, the review showed a reduction in LF indices of more than 50% and up to 100% post-MDA in endemic communities with high prevalence. The entomological assessment revealed a reduction in LF transmission post-MDA, which strongly supported the reduction of LF indices. Biannual MDA conducted further showed a marked reduction in LF indices compared to annual MDA. Double therapy of MDA significantly reduced the transmission indices to almost nil compared to single therapy. Conclusion: Review of MDA showed promising effects in which it reduced the prevalence microfilaraemia (mf) and Circulating Filarial Antigen (CFA) from baseline, as well as the clinical prevalence and entomological indices. Combination therapy showed better outcome compared to single therapy. Therefore, complementary vector control is suggested in addition to MDA, as well as education delivery to the endemic communities.

Simulation Research on Blood Detection Sensing with Parity-Time Symmetry Structure

To realize the design of a medical sensor with excellent comprehensive performance indexes, herein, a plasma concentration sensing model satisfying the Parity-Time (PT) symmetric condition is proposed. In this paper, the transfer matrix method was used to simulate the transmittance spectrum of the structure, according to the amplification effect on defect mode transmission and various detection performance indexes of the structure. We numerically optimized the parameters of the structure, such as the number of PT-symmetry unit cell N, the sample layer thickness dD as well as the macroscopic Lorentz oscillation intensity α in the PT-symmetry unit cell. The calculation results demonstrate that when the sample concentration changes from 0 g/L to 50 g/L, the wavelength of defect peak shifts from 1538 nm to 1561 nm, and the average quality factor, sensitivity, average figure of merit, average detection limit and average resolution of the structure can reach 78,564, 0.4409 nm/(g/L) (or 227.05 nm/RIU), 11,515 RIU−1, 5.1 × 10−6 RIU and 0.038 g/L, respectively. Not only the sensitivity and resolution of the PT-symmetry structure are better than that of the similar sensors, but it also has excellent comprehensive detection performance, which indicates that the developed sensor can be used in high-precision biomedical detection devices.

Multi-objective building design optimisation using acoustics and daylighting

Daylighting and acoustics parameters are related to each other in terms of material usage, specifically for window openings. However, no study has included acoustics and daylighting as objectives in the multi-objective optimisation models. In this study, this relationship was included to the optimisation process of generating building conceptual form. A model was developed to optimise the form of a building using acoustics, daylighting and floor area as the objectives. Daylight autonomy parameter for daylighting performance and C50 (speech clarity), reverberation time, Speech Transmission Index parameters for acoustic performance were used in the model which was created with visual programming language. Case studies were conducted with the model, and the results were discussed. Maximising speech clarity and maximising annual daylighting in the space were determined as objectives for the building form optimisation process in the case studies.

Paquitop.arm, a Mobile Manipulator for Assessing Emerging Challenges in the COVID-19 Pandemic Scenario

The use of automation and robotics technologies for caregiving and assistance has become a very interesting research topic in the field of robotics. The spread of COVID-19 has highlighted the importance of social distancing in hospitals and health centers, and collaborative robotics can bring substantial improvements in terms of sparing health workers basic operations. Thus, researchers from Politecnico di Torino are working on Paquitop.arm, a mobile robot for assistive tasks. The purpose of this paper is to present a system composed of an omnidirectional mobile platform, a 6 DOF robot arm, and a depth camera. Task-oriented considerations are made to estimate a set of mounting parameters that represents a trade-off between the exploitation of the robot arm workspace and the compactness of the entire system. To this end, dexterity and force transmission indexes are introduced to study both the kinematic and the static behavior of the manipulator as a function of the mounting parameters. Finally, to avoid singularities during the execution of the task, the platform approach to the task workspaces is studied.

Aryl‐group substituted polysiloxanes with high‐optical transmission, thermal stability, and refractive index

AbstractPolysiloxanes are an important class of polymers for optoelectronic applications. Novel polysiloxanes with high‐refractive index (RI) based on phenanthrenyl‐substituted monomers are prepared by a polycondensation reaction starting from various substituted dialkoxysilanes as monomers. The substitution patterns on the Si atom are systematically changed to vary the properties of the linear polymers as well as the final cured material. The two monomers with polycyclic aromatic side groups 9‐phenanthrenylmethyldimethoxysilane and 9‐phenanthrenylphenyldimethoxysilane are synthesized and fully characterized, including their single crystal X‐ray structures. Linear polysiloxanes with variations in hydride, methyl, vinyl, phenyl, and phenanthrenyl side group content are prepared by acid‐ and base‐catalyzed polycondensation reactions. Both SiH and Si vinyl substituted polymers with molecular weights up to 30 kDa and adjustable RI's from 1.52 to 1.63 are obtained and the thermally cured by Pt‐catalyzed hydrosilylation reactions. Polysiloxane resins are obtained with high‐RI's, optical transmittance above 95% and thermal stabilities up to 420°C. Long‐term thermal stability tests show transmittance values above 85% even after 60 days of thermal treatment at 180°C.

Audibility of emergency broadcasting sound in a mechanical room in an office building

Fire alarm and emergency broadcasting sound are important in fire and disaster situations. For the clear presentation of the fire alarm and emergency broadcasting sound to occupants of buildings, some guidelines and requirements were established. In NFPA 72 and BS standard, a specific alarm sound level for alarm sound of residential facilities was proposed and Speech Transmission Index(STI) was regulated for the emergency broadcasting system. In the fire and disaster situation, one of the important facility is a mechanical and electrical system to maintain water and electricity supply. To maintain this function in the buildings, clear presentation of emergency broadcasting sound to the workers in the mechanical and electrical room is crucial for the emergency operation of the system. In this study, the noise level in the mechanical rooms and electricity facilities of more than 40 years old office building were measured. Also, audibility and room acoustic properties such as reverberation time and STIwas simulated using Odeon 12. In order to deliver emergency broadcasting sound more clearly, sound absorption material and a soundproof chamber for noisy devices are needed. Also, the emergency broadcasting system in noisy facilities should be improved to produce the broadcasting sound louder and clearer.

Intelligibility of bone-conducted speech detected on the scalp

Bone-conduction microphones (BCMs) can detect speakers' voices with high signal-to-noise ratio even under extremely noisy environments like a machine factory or an engine room of a watercraft. BCMs are ordinarily attached to the front of the neck (larynx), therefore, it is sometimes accompanied by discomfort and esthetic problems. In order to solve such problems, we have been developing a novel BCM system built in a helmet, however, characteristics of bone-conducted speech detected on the scalp need to be clarified. In this study, mono-syllable articulations of bone-conducted speech detected at several locations on the head and neck were measured. Also, the speech transmission index (STI), objective measure of signal transmission quality, was calculated. The results indicated that the forehead and the vertex showed better articulation and STI than the mastoid process of the temporal bone, the mandibular condyle, and the occiput. In terms of the gender difference, the forehead and the vertex showed higher scores for the male voice, whereas the cheek showed the highest for the female voice. Additionally, the larynx showed lower scores than others. These results indicated that the attenuation of high-frequency components are smaller at the forehead and the vertex.

Impact of Partition types on Architecture design studios acoustical environment

Working in Architecture design studios environment requires various activities. Interaction, communication and meetings could affect the speech intelligibility and the speech privacy conditions. Students Areas with a more silent environment are needed with a minimized level of distraction from surrounding activities, while teamwork and discussion areas with a high level of interaction need a good speech intelligibility. One of the more important elements which can improve the open spaces acoustical conditions is the partitions between workstations.The main purpose of this work is to evaluate the acoustical performance of four partitions types in open plan offices; 1.10m two sides partition height, 1,50m front side partitions, 1,50m one side partitions and 1.50 two sides partitions. This Study was conducted in the College of Architecture, Imam Abdulrhman Bin Faisal University, KSA. Based on ISO 3382-3, Speech Transmission Index, STI in the nearest workstation, Distraction distance rD, privacy distance rP, A-weighted background noise level L,A,B and A-weighted SPL of speech at 4 metres L,A,S,4m have been measured. It was found that the best results can be obtained by 1.50m front side and 1.50m two sides partitions.

Contribution of Low-Level Acoustic and Higher-Level Lexical-Semantic Cues to Speech Recognition in Noise and Reverberation

Masking noise and reverberation strongly influence speech intelligibility and decrease listening comfort. To optimize acoustics for ensuring a comfortable environment, it is crucial to understand the respective contribution of bottom-up signal-driven cues and top-down linguistic-semantic cues to speech recognition in noise and reverberation. Since the relevance of these cues differs across speech test materials and training status of the listeners, we investigate the influence of speech material type on speech recognition in noise, reverberation and combinations of noise and reverberation. We also examine the influence of training on the performance for a subset of measurement conditions. Speech recognition is measured with an open-set, everyday Plomp-type sentence test and compared to the recognition scores for a closed-set Matrix-type test consisting of syntactically fixed and semantically unpredictable sentences (c.f. data by Rennies et al., J. Acoust. Soc. America, 2014, 136, 2642–2653). While both tests yield approximately the same recognition threshold in noise in trained normal-hearing listeners, their performance may differ as a result of cognitive factors, i.e., the closed-set test is more sensitive to training effects while the open-set test is more affected by language familiarity. All experimental data were obtained at a fixed signal-to-noise ratio (SNR) and/or reverberation time set to obtain the desired speech transmission index (STI) values of 0.17, 0.30, and 0.43. respectively, thus linking the data to STI predictions as a measure of pure low-level acoustic effects. The results confirm the consistent difference between robustness to reverberation observed in the literature between the matrix type sentences and the Plomp-type sentences, especially for poor and medium speech intelligibility. The robustness of the closed-set matrix type sentences against reverberation disappeared when listeners had no a priori knowledge about the speech material (sentence structure and words used), thus demonstrating the influence of higher-level lexical-semantic cues in speech recognition. In addition, the consistent difference between reverberation- and noise-induced recognition scores of everyday sentences for medium and high STI conditions and the differences between Matrix-type and Plomp-type sentence scores clearly demonstrate the limited utility of the STI in predicting speech recognition in noise and reverberation.

Assessment of speech intelligibility in university lecture rooms of different sizes using objective and subjective methods

The scores of speech intelligibility, obtained using objective and subjective methods for three university lecture rooms of the small, medium, and large sizes with different degrees of filling, were presented. The problem of achieving high speech intelligibility is relevant for both students and university administration, and for architects designing or reconstructing lecture rooms. Speech intelligibility was assessed using binaural room impulse responses which applied an artificial head and non-professional quality audio equipment for measuring. The Speech Transmission Index was an objective measure of speech intelligibility, while the subjective evaluation of speech intelligibility was carried out using the articulation method. Comparative analysis of the effectiveness of parameters of impulse response as a measure of speech intelligibility showed that Early Decay Time exceeded the score of the T30 reverberation time but was ineffective in a small lecture room. The C50 clarity index for all the considered lecture rooms was the most informative. Several patterns determined by the influence of early sound reflections on speech intelligibility were detected. Specifically, it was shown that an increase in the ratio of the energy of early reflections to the energy of direct sound leads to a decrease in speech intelligibility. The exceptions are small, up to 30‒40 cm, distances from the back wall of the room, where speech intelligibility is usually slightly higher than in the middle of the room. At a distance of 0.7–1.7 m from the side walls of the room, speech intelligibility is usually worse for the ear, which is closer to the wall. The usefulness of the obtained results lies in refining the quantitative characteristics of the influence of early reflections of sound on speech intelligibility at different points of lecture rooms.

The effect of low frequency reverberation on Chinese speech intelligibility in two classrooms

The previous study had investigated the students’ speech perceptions in two primary school classrooms with similar reverberation time and found that the speech intelligibility in a classroom was better than that in other one. It is speculated that due to difference in the improvement in low frequency reverberation. In this study, the reverberation time and speech transmission index were obtained and compared from these two classrooms by simulated. The subjective Chinese speech intelligibility was evaluated through simulated binaural room impulse responses. The effect of low frequency reverberation on Chinese speech intelligibility in two classrooms was discussed. The result shows that improving the low frequency characteristic of reverberation time can be helpful to improve the Chinese speech intelligibility in classroom.

Performance evaluation of a special 6-PUS type parallel manipulator

AbstractIn this paper, a special 6-PUS parallel manipulator (PM) is utilized as a shaking table. Unlike the existing results about 6-PUS PMs, we make the actuator direction collinear with the linkage direction at neutral position. With respect to the application background, a further analysis of the special PM is carried out from the perspective of motion/force transmissibility, natural frequency and acceleration capability. Specially, the complete dynamics model is established based on the Kane method. Then, generalized transmission indices based on the screw theory are utilized to reflect its motion ability, and a model of natural frequency is proposed with the axial stiffness of linkages considered. Finally, the effect of the angle between the actuator direction and the linkage direction α on various performances is analyzed, and other results are included to illustrate its feasibility and usability.

Hybrid algorithm for multi-objective optimization design of parallel manipulators

In this paper, a hybrid algorithm was proposed for multi-objective optimization design with high efficiency and low computational cost based on the Gaussian process regression and particle swarm optimization algorithm. For the proposed method, the global performance indices, including regular workspace volume, global transmission index, global stiffness index, and global dynamic index were considered as objective functions. First, the multi-objective optimization problem considering the boundary conditions, objective, and constraint functions was constructed. Second, the Latin hypercube design was regarded as the design of experiment to obtain the computer sample points. Besides, the high-precision objective-function values were obtained by increasing the node density in the workspace at these sample points to provide sufficient information for the mapping model. Third, the Gaussian process regression was proposed to build the mapping model between the objective functions and the design parameters, thus reducing the computational cost of global performance indices. Cross-validation and external validation were adopted to verify the mapping model. Finally, the hybrid algorithm combined with the Gaussian process regression and particle swarm optimization algorithm was proposed for multi-objective optimization design. The 2PRU-UPR parallel manipulator was taken as a case to implement the proposed method (where P was a prismatic joint; R a revolute joint; U a universal joint). The comparison from the back propagation neural network, multivariate regression, and Gaussian process regression mapping models showed that the Gaussian process regression model had higher accuracy and robustness. The proposed hybrid algorithm saved 99.84% of computational cost compared to using the particle swarm optimization algorithm. The Pareto frontier of the multi-objective optimization problem of the 2PRU-UPR parallel manipulator was also obtained. After optimization, the performance indices were significantly improved.