Indoor Micro Research Articles

Occurrence and exposure evaluation of bisphenol A and its analogues in indoor and outdoor dust from China

Bisphenol A (BPA) and its analogues have been proved to be harmful to human reproduction, endocrine and nervous system. But information on the occurrence and human exposure to bisphenol compounds (BPs) in dust (especially outdoor dust) is limited. In this study, 14 BPs were determined in 174 indoor dust samples and 202 outdoor dust samples from Chinese mainland, Hong Kong, Macau and Taiwan. BPA, BPS, BPAF, BPF, BPAP and BPE were widely detected with detection frequencies of 98.94 %, 98.67 %, 97.87 %, 95.21 %, 87.23 % and 71.54 %, respectively. The median total concentrations of the most detected six BPs in the dust were in the order of south urban indoors (556 ng/g) > south rural outdoors (438 ng/g) > south urban outdoors (432 ng/g) > south rural outdoors (418 ng/g) > north rural indoors (412 ng/g) > north urban outdoors (341 ng/g) > north urban indoors (311 ng/g) > north rural outdoors (246 ng/g). The amounts of garbage incineration, plastic output and recycled paper may have influence on the BPs levels. Some BPs (BPAF, BPAP, BPF and BPS) in the indoor and outdoor samples were significantly positively correlated. In addition, the BPs in the indoor dust from different indoor micro environments in Chengdu were investigated. BPA (median concentration: 571.2 ng/g) and BPF (median concentration: 114.3 ng/g) were the two primary BPs, accounting for 78.1 % of the median total concentrations of the investigated BPs. High concentration of BPA appeared in printing workshops and offices, while high concentration of BPAP, BPC, BPE and BPF appeared in electronic repair shops. Occupational exposure to BPs deserves attention in the future. ΣBPs exposure risk for children and adults in the urban areas of southern China was the highest. To our knowledge, this is the first report in China to study BPs in outdoor dust sample.

A Broadband Gain-Enhanced Conical-Beam Antenna Loaded With the Multicircle Sectored Metasurface

A broadband gain-enhanced monopole antenna loaded with metasurface is designed in this paper, which is suitable for sub-6 GHz fifth-generation (5G) applications. The multi-circle sectored metasurface antenna is analyzed through the evolution process and field distribution. With the addition of the metasurface, the antenna’s relative bandwidth is increased from 23.25% to 48.5%, and the in-band gain is improved by 2 dBi. To validate the proposed working principles and design guidelines, the proposed antenna is fabricated and measured. Measured results agree well with the simulated ones and show that the -10 dB impedance bandwidth is 56% (3.25-5.78 GHz), covering the 5G frequency band (3.3-3.6, 4.8-5 GHz). The average gain in the desired band is 7 dBi with a variation of ±1 dBi, which is suitable for 5G indoor micro ceiling base station applications.

A randomized cross-over trial investigating differences in 24-h personal air and skin temperatures using wearable sensors between two climatologically contrasting settings

The influence of elevated air temperatures recorded in various urban microenvironments in adversely impacting biologically relevant disease end points has not yet been extensively tackled. This study is a post hoc analysis of the TEMP pilot trial, a randomized 2 × 2 cross-over trial that examined changes in metabolic and stress hormonal profiles of healthy adults in two settings (urban vs. rural) with distinctly different climatological characteristics during the Mediterranean summer. This analysis aimed to study the association between the 24-h personal air or skin temperature sensor measurements and the diary-based location type (indoors vs. outdoors) in urban (seaside) vs. rural (higher in altitude) microenvironments. Out of 41 eligible participants, a total of 37 participants were included in this post-hoc TEMP trial analysis. Wearable sensors recorded personal air temperature, skin temperature, and activity (as a surrogate marker of physical activity) in each setting, while a time-stamped personal diary recorded the types of indoor or outdoor activities. Temperature peaks during the 24-h sampling period were detected using a peak finding algorithm. Mixed effect logistic regression models were fitted for the odds of participant location (being indoors vs. outdoors) as a function of setting (urban vs. rural) and sensor-based personal temperature data (either raw temperature values or number of temperature peaks). During the study period (July–end of September), median [interquartile range, IQR] personal air temperature in the rural (higher altitude) settings was 1.5 °C lower than that in the urban settings (27.1 °C [25.4, 29.2] vs. 28.6 °C [27.1, 30.5], p < 0.001), being consistent with the Mediterranean climate. Median [IQR] personal air temperature in indoor (micro)environments was lower than those in outdoors (28.0 °C [26.4, 30.3] vs 28.5 °C [26.8, 30.7], p < 0.001). However, median [IQR] skin temperature was higher in indoor (micro)environments vs. outdoors (34.8 °C [34.0, 35.6] and 33.9 °C [32.9, 34.8], p < 0.001) and the number of both personal air and skin temperature peaks was higher indoors compared to outdoors (median [IQR] 3.0 [2.0,4.0] vs 1.0 [1.0,1.3], p < 0.007, for the skin sensors). A significant association between the number of temperature peaks and indoor location types was observed with either the personal air sensor (OR 3.1; 95% CI 1.2–8.2; p = 0.02) or the skin sensor (OR 3.7; 95% CI 1.4–9.9; p = 0.01), suggesting higher number of indoor air temperature fluctuations. Amidst the global climate crisis, more population health studies or personalized medicine approaches that utilize continuous tracking of individual-level air/skin temperatures in both indoor/outdoor locations would be warranted, if we were to better characterize the disease phenotype in response to climate change manifestations.

Spatiotemporal variation of the indoor mycobiome in daycare centers

BackgroundChildren spend considerable time in daycare centers in parts of the world and are exposed to the indoor micro- and mycobiomes of these facilities. The level of exposure to microorganisms varies within and between buildings, depending on occupancy, climate, and season. In order to evaluate indoor air quality, and the effect of usage and seasonality, we investigated the spatiotemporal variation in the indoor mycobiomes of two daycare centers. We collected dust samples from different rooms throughout a year and analyzed their mycobiomes using DNA metabarcoding.ResultsThe fungal community composition in rooms with limited occupancy (auxiliary rooms) was similar to the outdoor samples, and clearly different from the rooms with higher occupancy (main rooms). The main rooms had higher abundance of Ascomycota, while the auxiliary rooms contained comparably more Basidiomycota. We observed a strong seasonal pattern in the mycobiome composition, mainly structured by the outdoor climate. Most markedly, basidiomycetes of the orders Agaricales and Polyporales, mainly reflecting typical outdoor fungi, were more abundant during summer and fall. In contrast, ascomycetes of the orders Saccharomycetales and Capnodiales were dominant during winter and spring.ConclusionsOur findings provide clear evidences that the indoor mycobiomes in daycare centers are structured by occupancy as well as outdoor seasonality. We conclude that the temporal variability should be accounted for in indoor mycobiome studies and in the evaluation of indoor air quality of buildings.DQRJQ2kAZZpV3giuEAS-rtVideo abstract

Low-Profile Wideband Omnidirectional Antenna for 4G/5G Indoor Base Station Application Based on Multiple Resonances

A novel low-profile antenna with monopole-like radiation characteristics is proposed for 4G/5G indoor micro ceiling base station applications. The proposed antenna consists of a top loading disk, two polygonal copper sheets, which are orthogonally intersected, and a circular printed circuit board (PCB), which serves as the ground. A prototype is fabricated and measured. The proposed antenna has a very low profile of 0.057λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> , where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> is the free-space wavelength at the lowest frequency of the operating band. A fractional bandwidth of 85.3% ranging from 1.6 to 3.98 GHz with |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB is achieved, which covers the 4G LTE band and 5G N78 band. The proposed antenna demonstrates consistent monopole-like radiation pattern in the whole working band, which is very suitable and well designed for indoor ceiling base station applications.

A Low-Profile Vertically Polarized Antenna With Conical Radiation Pattern for Indoor Micro Base Station Application

A novel low-profile vertically polarized wideband monopole antenna is proposed. A central-fed circular patch antenna, which is shorted concentrically by three metal pins, is initially adopted to excite TM01 and TM02 modes. Then, a fan-shaped clearance area is cut out in the angular area between each two shorting pins. Finally, three mushroomlike structures are placed in the clearance area, which, together with the feeding probe, form three split ring resonators (SRRs) that introduce an extra resonance, thereby substantially expanding the antenna operation bandwidth. All the three modes have radiation patterns similar to the conventional monopole. The proposed antenna has a very low profile of 0.06 λmin and a lateral dimension of π × (0.176 λmin)2, where λmin is the free-space wavelength at the lowest frequency of operation. A simulated impedance bandwidth for | S 11| < −10 dB of about 48.5% ranging from 1.7 to 2.79 GHz is achieved, which fully covers the 4G LTE band, while the measured result shows a wider fractional bandwidth of 66%.

A Low-Profile Wideband Antenna With Monopolelike Radiation Characteristics for 4G/5G Indoor Micro Base Station Application

A wideband, low-profile, vertically polarized antenna with monopolelike radiation characteristics is proposed for 4G/5G indoor base station applications. The design of this antenna is based on the traditional monocone antenna with internal matching and reactive load. The structure of monocone is realized by crossed substrate, which reduces the antenna weight and improves the design flexibility simultaneously. Then, reactive loading of capacitively coupled triangle patches and shorting pins are used to reduce the height of antenna profile to 0.08 λ min, where λ min is the free-space wavelength at the lowest operation frequency. An interdigital capacitor is etched near the antenna's input to adjust the impedance matching. The proposed antenna demonstrates consistent monopolelike, omnidirectional radiation patterns within the operating band. A measured impedance bandwidth for voltage standing-wave ratio (VSWR) < 2.2 of about 81% ranging from 1.66 to 3.95 GHz is achieved, which covers 1.7–2.7 GHz 4G Long-Term Evolution band and 3.3–3.8 GHz 5G N78 band simultaneously. The proposed antenna is tailored for the ceiling micro base station in indoor distributed system.

The Distribution and Sources of Heavy Metals in Fine Particulate Matter in an Indoor Micro Environment of a Residential Area of Lagos state, Nigeria

The Distribution and Sources of Heavy Metals in Fine Particulate Matter in an Indoor Micro Environment of a Residential Area of Lagos state, Nigeria

Robust I&amp;I Adaptive Control for a Class of Quadrotors With Disturbances

This article presents a robust adaptive control based on Immersion and Invariance (I&I) method for a class of quadrotors subject to disturbances. The nonlinear model of the considered quadrotor including position subsystem and attitude subsystem is established, which has the characteristics of high nonlinearity, underactuation and strong coupling between the subsystems. To achieve satisfying position tracking performance, an I&I adaptive control approach is proposed for the uncertain position subsystem. To enhance the robustness of the attitude subsystem subject to disturbances, a robust adaptive control law based on disturbance observer (DO) is developed to stabilize the subsystem. The DO for the attitude subsystem is constructed to accommodate unknown external disturbances and a robust adaptive bounding law is designed to dominate the modelling errors. The ultimate boundedness of all the signals in the closed-loop system is proved by Lyapunov-based stability analysis. Experimental results performed on an actual indoor micro quadrotor indicate a better performance of the proposed controller compared with the nominal controller without robust and adaptive parts.

Learnable Line Segment Descriptor for Visual SLAM

Traditionally, the indirect visual motion estimation and simultaneous localization and mapping (SLAM) systems were based on point features. In recent years, several SLAM systems that use lines as primitives were suggested. Despite the extra robustness and accuracy brought by the line segment matching, the line segment descriptors used in such systems were hand-crafted, and therefore sub-optimal. In this paper, we suggest applying descriptor learning to construct line segment descriptors optimized for matching tasks. We show how such descriptors can be constructed on top of a deep yet lightweight fully-convolutional neural network. The coefficients of this network are trained using an automatically collected dataset of matching and non-matching line segments. The use of the fully-convolutional network ensures that the bulk of the computations needed to compute descriptors is shared among the multiple line segments in the same image, enabling efficient implementation. We show that the learned line segment descriptors outperform the previously suggested hand-crafted line segment descriptors both in isolation (i.e., for the subtask of distinguishing matching and non-matching line segments), but also when built into the SLAM system. We construct a new line based SLAM pipeline built upon a state-of-the-art point-only system. We demonstrate generalization of the learned parameters of the descriptor network between two well-known datasets for autonomous driving and indoor micro aerial vehicle navigation.

Robust H∞ compensator with constraints for attitude manoeuvres of a quadrotor subject to unknown stochastic input delays

ABSTRACTThis paper addresses the robust compensator design problem for the attitude tracking of an indoor micro quadrotor subject to unknown stochastic input delays and input constraints. The attitude dynamics of the micro quadrotor is modelled as a nonlinear system with linear parametric uncertainties, unknown stochastic input delays, input constraints and disturbances. Based on the uncertain model and the Hanlanay's inequality, both robust attitude tracking controller and suboptimal robust controller with constraints are developed by constructing an appropriate Lyapunov–Krasvokii function and presenting standard linear matrix inequalities. The suggested controllers not only achieve the exponential stabilisation of attitude of the quadrotor but also guarantee the given performance. Finally, both numerical simulation and experimental results are provided to illustrate the effectiveness and merits of the proposed methods.

Minimum Sigma Set SR-UKF for Quadrifocal Tensor-based Binocular Stereo Vision-IMU Tightly-coupled System

This paper presents a binocular vision-IMU (Inertial Measurement Unit) tightly-coupled structure based on a Minimum sigma set Square-Root Unscented Kalman Filter (M-SRUKF) for real time navigation applications. Though the M-SRUKF has only half the sigma points of the SRUKF, it has the same accuracy as the SRUKF when applied to the binocular vision-IMU tightly-coupled system. As the Kalman filter flow is a kind of square-root system, the stability of the system can be guaranteed. The measurement model and the outlier rejection model of this tightly-coupled system not only utilises the epipolar constraint and the trifocal tensor geometry constraint between the consecutive two image pairs, but also uses the quadrifocal tensor geometry among four views. The structure of the binocular vision-IMU tightly-coupled system is in the form of an error state, and the time updates of the state and the state covariance are directly estimated without using Unscented Transformation (UT). Experiments are carried out based on an outdoor land vehicle open source dataset and an indoor Micro Aerial Vehicle (MAV) open source dataset. Results clearly show the effectiveness of the proposed new mechanisation.

Phthalate esters in settled dust of different indoor microenvironments; source of non-dietary human exposure

This study reports levels and profiles of phthalates in dust samples collected from three different microenvironments (cars, air conditioner (AC) filters and household floor dust) of Saudi Arabia (KSA) and Kuwait. To the best of our knowledge, this is a very first study in the literature reporting phthalates in the indoor environments of KSA, which makes these findings very important. Our results showed that bis(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), di-isobutyl phthalate (DIBP), and di-n-octyl phthalate (DNOP) were the major chemicals in all dust samples. DEHP was the overwhelming compound in all microenvironments occurred at median concentrations (μg/g) of 1020, 1250, and 790 in Saudi household floor, car, and AC filter dust, respectively. The median levels (μg/g) of DEHP in Kuwaiti car (320) and household floor (240) dust samples were 3–4 times lower than respective Saudi dust. Phthalates were higher in car dust than household dust and Ac filter dust, suggesting people spending more time in vehicles are at higher risk of exposure to these chemicals. Different exposure scenarios, using 5th percentile, median, mean, and 95th percentile levels, were estimated for adults and toddlers. For Saudi and Kuwaiti toddlers worst exposure scenario for DEHP, a cardiotoxic and endocrine disruptor, was calculated at 37630 and 6722ng/kg body weight/day (ng/kg bw/d), respectively. This preliminary study provided first-hand baseline data of Phthalates from Gulf countries and which necessitate more detailed future studies in this region. Practical implicationsThe first study on the incidence of phthalates from different micro–environments of KSA. High levels of bis(2-ethylhexyl) phthalate (DEHP) were present in Kuwaiti and KSA indoor micro–environments suggesting a high use of DEHP in consumer products. Exposure to phthalates via dust ingestion is estimated high in Saudi toddlers, which is a cause of concern.

Vision-based Line Tracking for an Indoor Micro Quadrotor

This paper proposes an algorithm for a vision-based line tracking for an indoor micro quadrotor. An onboard vision camera is used to detect the line information. Afterwards, captured images are sent to a ground control station (GCS) via wireless connection thus to process the image in real-time. In order to design the PID controller, this sent information is used in feedback of the control loop. GCS calculates present yaw measurement and distance between line path and quadrotor, and this information is sent to a quadrotor onboard controller. Afterwards, yaw angle is stabilized by the PID controller and distance is minimized by the fuzzy-like controller which is proposed in this paper. Finally, experimental results validate the effectiveness of the proposed method.

1A2-C21 視覚情報による小型ヘリコプタの飛行制御

This paper presents vision based flight control of an indoor micro helicopter by using visual SLAM. A small single wireless camera is put on the helicopter. Visual information obtained by the camera is used to estimate position and posture of the helicopter in real time by utilizing visual SLAM (PTAM). We construct the measurement system with the calibration function from the local coordinate system in PTAM to the world coordinate system and with the functions of noise detection and elimination. By using the constructed system, hovering flight and path tracking control of indoor micro helicopter are performed.

1A2-E15 搭載カメラのみを用いた屋内用小型ヘリコプタの自己位置・姿勢推定と飛行制御

This paper presents vision based flight control of an indoor micro helicopter in the corridor of buildings. Since the helicopter has limited payload, a small single wireless camera is employed on a sole sensor device. Visual information obtained by the camera is used to estimate position of the helicopter related to the corridor. We focus on edge lines between walls and floor of the corridor and vanishing points on the shot image. Real time measurement and flight control are performed with the real indoor micro helicopter. At the first step, the experiments are held in the ideal environment which is simulated to the corridor and autonomous hovering flight was succeeded. Finally, we have experiments in the real corridor and achieve hovering flight and straight-ahead fight control.

Towards Autonomous Indoor Micro VTOL

Recent progress in sensor technology, data processing and integrated actuators has made the development of miniature flying robots fully possible. Micro VTOL1 systems represent a useful class of flying robots because of their strong capabilities for small-area monitoring, building exploration and intervention in hostile environments. In this paper, we emphasize the importance of the VTOL vehicle as a candidate for the high-mobility system emergence. In addition, we describe the approach that our lab2 has taken to micro VTOL evolving towards autonomy and present the mechanical design, dynamic modelling, sensing, and control of our indoor VTOL autonomous robot OS4.3

Theoretic capacity evaluation of indoor micro- and macro-MIMO systems at 5 GHz using site specific ray tracing

Simulation results for the capacity distribution of an indoor multiple input multiple output (MIMO) communications system are presented. Results are based on ray traced propagation data for micro- and macro-MIMO array configurations. Capacity levels are compared with well-known mathematical results for uncorrelated Rayleigh fading. Significant capacity gains are seen using a macro-MIMO configuration.