People in unfamiliar environments often need navigation guidance to reach a destination. Research has found that compared to outdoors, people tend to lose orientation much more easily within complex buildings, such as university buildings and hospitals. This paper proposes a category-based method to generate landmark-based route instructions to support people's wayfinding activities in unfamiliar indoor environments. Compared to other methods relying on detailed instance-level data about the visual, semantic, and structural characteristics of individual spatial objects, the proposed method relies on commonly available data about categories of spatial objects, which exist in most indoor spatial databases. With this, instructions like "Turn right after the second door, and use the elevator to go to the second floor" can be generated for indoor navigation. A case study with a university campus shows that the method is feasible in generating landmark-based route instructions for indoor navigation. More importantly, compared to metric-based instructions (i.e., the benchmark for indoor navigation), the generated landmark-based instructions can help users to unambiguously identify the correct decision point where a change of direction is needed, as well as offer information for the users to confirm that they are on the right way to the destination.

Recently, a number of empirical models have been introduced in the literature for the behavior of direct path used in the design of algorithms for RF based indoor geolocation. Frequent absence of direct path has been a major burden on the performance of these algorithms directing researchers to discover algorithms using multipath diversity. However, there is no reliable model for the behavior of multipath components pertinent to precise indoor geolocation. In this dissertation, we first examine the absence of direct path by statistical analysis of empirical data. Then we show how the concept of path persistency can be exploited to obtain accurate ranging using multipath diversity. We analyze the effects of building architecture on the multipath structure by demonstrating the effects of wall length and wall density on the path persistency. Finally, we introduce a comprehensive model for the spatial behavior of multipath components. We use statistical analysis of empirical data obtained by a measurement calibrated ray-tracing tool to model the time-of- arrival, angle-of-arrival and path gains. The relationship between the transmitter-receiver separation and the number of paths are also incorporated in our model. In addition, principles of ray optics are applied to explain the spatial evolution of path gains, time-of-arrival and angle-of-arrival of individual multipath components as a mobile terminal moves inside a typical indoor environment. We also use statistical modeling for the persistency and birth/death rate of the paths.

Our increased reliance on localization devices such as GPS navigation has led to an increased demand for localization solutions in all environments, including indoors. Indoor localization has received considerable attention in the last several years for a number of application areas including first responder localization to targeted advertising and social networking. The difficult multipath encountered indoors degrades the performance of RF based localization solutions and so far no optimal solution has been published. This dissertation presents an algorithm called Coherent Array Reconciliation Tomography (CART), which is a Direct Positioning Algorithm (DPA) that incorporates signal fusion to perform a simultaneous leading edge and position estimate for a superior localization solution in a high multipath environment. The CART algorithm produces position estimates that are near optimal in the sense that they achieve nearly the best theoretical accuracy possible using an Impulse Radio (IR) Ultra-Wideband (UWB) waveform. Several existing algorithms are compared to CART including a traditional two step Leading Edge Detection (LED) algorithm, Singular value Array Reconciliation Tomography (SART), and Transactional Array Reconciliation Tomography (TART) by simulation and experimentation. As shown under heavy simulated multipath conditions, where traditional LED produces a limited solution and the SART and TART algorithms fail, the CART algorithm produces a near statistically optimal solution. Finally, the CART algorithm was also successfully demonstrated experimentally in a laboratory environment by application to the fire fighter homing device that has been a part of the ongoing research at Worcester Polytechnic Institute (WPI).

This thesis is a part of a research project performed by two MS students Yang Yang and the author. The overall objective of the project is the design, implementation, and performance evaluation of algorithms for newborn localization and tracking in hospitals using Apple iBeacon technology. In the research project, I lead the path-loss modeling of iBeacon, design of algorithms for in-room presence detection system, and analysis of the accelerometer sensor. My partner, Yang Yang, leads the performance evaluation of the localization system using Cramer Rao Lower Bound (CRLB). This manuscript describes the project with a focus on my contributions in modeling the behavior of sensors and presence detection algorithms. Today, RFID detection is the most popular indoor detection technique. It provides high precision detection rate to distinguish the number of people in certain rooms of a building. However, special scanners and manual operations are required. This increases the cost and operation complexity. With the recent introduction of iBeacon by Apple, possibility of more efficient in-room presence detection has emerged for specific applications. An example of these applicatons is recording the number of visitors and newborns in a nursery room inside a hospital. The iBeacon uses Bluetooth Low Energy (BLE) technology for proximity broadcasting. Additionally, iBeacon carries a motion detection sensor, which can be utilized for counting the number of people and newborns entering and leaving a room. In this thesis we introduce a novel intelligent in-room presence detection system using iBeacon for the newborns in hospitals to determine the number of visitors and newborns' location in the nursery room. We first develop a software application on iPhone to receive and extract the necessary data from iBeacon for further analysis. We build the path-loss model for the iBeacon based on the received signal strength (RSS) of the iBeacon, which is used for performance evaluation using CRLB in Yang Yang's project. We also utilize the accelerometer in the smart phones to improve the performance of our detection system.

Mycotoxins are secondary metabolites produced by many fungal species. Health effects induced by the ingestion of these substances are well documented and some mycotoxins are now regulated for their maximum tolerable levels in foods. However, other routes of exposure to these contaminants are possible. Thus, if irritating or allergenic reactions related to the inhalation of fungal spores or mycelial fragments have been demonstrated, inhalation of mycotoxins is also suspected to be causing certain respiratory disorders or certain pathologies. Indeed, mycotoxins can be found in spores but also on finer particles which are easily aerosolized and therefore likely to be inhaled. However, data on the hazard associated with human exposure to mycotoxins by inhalation are still very fragmented. In this context, our main objective was to characterize the aerosolization of mycotoxins during the colonization of different materials encountered in indoor environments by toxinogenic molds. First we studied growth and production of mycotoxins during the colonization of building materials (wallpaper, painted fiberglass wallpaper, vinyl wallpaper, fir, fiberglass) by three fungal species of interest: Aspergillus versicolor, Penicillium brevicompactum, Stachybotrys chartarum. These species were chosen because of their frequent presence in indoor environments and their diverse mycelial organization. In addition, these three species produce different toxins: sterigmatocystin, mycophenolic acid and macrocyclic trichothecenes for A. versicolor, P. brevicompactum and S. chartarum, respectively. These studies have shown that, during their development on tested materials, three species produce mycotoxins. The most favorable material for fungal development and toxinogenesis is wallpaper. Mycophenolic acid, sterigmatocystin and macrocyclic trichothecenes can thus be produced at levels of 1.8, 112.1 and 27.8 mg/m2, respectively, on this material. These toxins can then be partially aerosolized. We have shown that aerosolization depends on species and their mycelial structure, but also on culture conditions and airflow. This transfer to air is nevertheless observed after aeraulic solicitations which can be easily encountered in indoor environments because theycorrespond to the movement of people in a room (0.3 m/s), speed of air in ceiling diffusers (2 m/s), slamming doors or air drafts when opening windows(6 m/s). P. brevicompactum showed to be the easiest to aerosolize. The major part of the aerosols’ toxic charge is found in particles whose size corresponds to that of spores or mycelial fragments. However, for macrocyclic trichothecenes, toxins were also found in particles smaller than spores, which could easily be inhaled by occupants and penetrate deep into the respiratory tract. In order to better characterize the actual hazard associated with inhalation of these compounds, cytotoxicity studies have been performed using lung cells and comparing with results observed on digestive cells. Pulmonary toxicity is comparable to that observed in digestive cells. Macrocyclic trichothecenes are much more toxic than other tested toxins with IC50 in order of ng/ml. In parallel, we analyzed the VOCs specifically produced during active mycotoxinogenesis in order to identify potential biomarkers of the actual production of mycotoxins that could be used as tools for monitoring of indoor environments. Unfortunately, this approach has not, for the moment, led to the identification of specific targets. In the end, we evaluated the persistence of these contaminants during application of bleach, the most frequently used decontamination process. We have shown that a normal cleaning procedure allows only partial removal of mold.

The principal objectives of this research are: to investigate the performance of different fingerprint-based WiFi Indoor Positioning Systems (IPS), analyse historical long-term data signals, detection of signal change points and outliers; then present an enhanced method that generates temporal based fingerprints. The proposed method consists of analysing signal strength profiles over time and detecting points at which the profile behaviour changes. This methodology can be used to dynamically adjust the fingerprint based on environmental factors, and with this select the relevant Wireless Access Points (WAPs) to be used for fingerprinting. The use of an Exponentially Weighted Moving Average (EWMA) Control Chart is investigated for this purpose. A long-term analysis of the WiFi scenery is presented and used as a test-bed for evaluation of state-of-the-art fingerprinting techniques. Data was collected and analysed over a period of 18 months, with over 840 different WAPs detected in over 77,000 observations covering 47 different locations of varying characteristics. A fully functional IPS has been developed and the design and implementation is described in this thesis. The system allows the scanning and recording of WiFi signals in order to define the generation of temporal fingerprints that can create radio-maps, which then allow indoor positioning to occur. This thesis presents the theory behind the concept and develops the technology to create a testable implementation. Experiments and their evaluation are also included. Based on the timestamp experiments the proposed system shows there is still room level accuracy, with a reduction in radio-map size.

Chan Pui-Ling. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 169-182). / Text in English; abstracts in English and Chinese. / Chan Pui-Ling. / Acknowledgements --- p.i / Abstracts --- p.ii / Table of Contents --- p.v / List of Plates --- p.ix / List of Figures --- p.xii / List of Tables --- p.xiv / Abbreviations --- p.xviii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Indoor Air Quality (IAQ): An overview --- p.1 / Chapter 1.1.1 --- Importance of indoor air quality --- p.2 / Chapter 1.1.2 --- Common indoor air pollutants --- p.2 / Chapter 1.1.3 --- Airborne bacteria --- p.4 / Chapter 1.1.3.1 --- Possible sources of airborne bacteria --- p.4 / Chapter 1.1.3.2 --- Health effects of the airborne bacteria --- p.5 / Chapter a. --- Sick building syndromes --- p.5 / Chapter b. --- Building-related illness --- p.7 / Chapter 1.1.4 --- Importance of studying airborne bacteria --- p.12 / Chapter 1.2 --- Situation in Hong Kong --- p.13 / Chapter 1.2.1 --- Outdoor air quality --- p.14 / Chapter 1.2.2 --- Indoor air quality --- p.14 / Chapter 1.2.2.1 --- Hong Kong studies --- p.16 / Chapter 1.2.3 --- Air quality objectives in Hong Kong --- p.18 / Chapter 1.3 --- Different sampling methods --- p.18 / Chapter 1.4 --- Identification of bacteria --- p.24 / Chapter 1.5 --- Site selection --- p.26 / Chapter 2 --- Objectives --- p.28 / Chapter 3 --- Materials and methods --- p.29 / Chapter 3.1 --- Samples collection --- p.29 / Chapter 3.1.1 --- Sampling site --- p.29 / Chapter 3.1.2 --- Complete Biosampler System --- p.29 / Chapter 3.1.3 --- Sampling preparation --- p.33 / Chapter 3.1.4 --- Sampling procedures --- p.33 / Chapter 3.2 --- Recovery of the airborne bacteria --- p.36 / Chapter 3.2.1 --- Cultural medium --- p.36 / Chapter 3.2.2 --- Recovery procedures --- p.36 / Chapter 3.2.3 --- Frozen stocks --- p.37 / Chapter 3.3 --- Indentification of bacterial strains --- p.37 / Chapter 3.3.1 --- Gram stain --- p.37 / Chapter 3.3.1.1 --- Chemical reagents --- p.37 / Chapter 3.3.1.2 --- Gram stain procedures --- p.38 / Chapter 3.3.2 --- Oxidase test --- p.38 / Chapter 3.3.2.1 --- Chemical reagents --- p.38 / Chapter 3.3.2.2 --- Oxidase test procedures --- p.41 / Chapter 3.3.3 --- Midi Sherlock® Microbial Identification System (MIDI) --- p.41 / Chapter 3.3.3.1 --- Culture medium --- p.41 / Chapter 3.3.3.2 --- Chemical reagents --- p.41 / Chapter 3.3.3.3 --- MIDI procedures --- p.41 / Chapter 3.3.4 --- Biolog MicroLogTM system (Biolog) --- p.41 / Chapter 3.3.4.1 --- Culture medium --- p.41 / Chapter 3.3.4.2 --- Chemical reagents --- p.44 / Chapter 3.3.4.3 --- Biolog procedures --- p.44 / Chapter 3.3.5 --- DuPont Qualicon RiboPrinter® Microbial Characterization System (RiboPrinter) --- p.46 / Chapter 3.3.5.1 --- Culture medium --- p.46 / Chapter 3.3.5.2 --- Chemical reagents --- p.46 / Chapter 3.3.5.3 --- RiboPrinter procedures --- p.46 / Chapter 4 --- Results --- p.50 / Chapter 4.1 --- Sample naming system --- p.50 / Chapter 4.2 --- Interpretation of results --- p.50 / Chapter 4.2.1 --- Midi Sherlock® Microbial Identification System (MIDI) --- p.51 / Chapter 4.2.2 --- Biolog MicroLog´ёØ System (Biolog) --- p.51 / Chapter 4.2.3 --- DuPont Qualicon RiboPrinter® Microbial Characterization System (RiboPrinter) --- p.52 / Chapter 4.3 --- Sample results --- p.53 / Chapter 4.3.1 --- Sample 1 (Spring) --- p.53 / Chapter 4.3.2 --- Sample 2 (Summer-holiday) --- p.62 / Chapter 4.3.3 --- Sample 3 (Summer-school time) --- p.71 / Chapter 4.3.4 --- Sample 4 (Autumn) --- p.81 / Chapter 4.3.5 --- Sample 5 (Winter) --- p.90 / Chapter 4.4 --- Bacterial profile of the student canteen --- p.100 / Chapter 4.5 --- The cell and colony morphology of the dominant bacteria --- p.100 / Chapter 4.6 --- Comparison between samples --- p.121 / Chapter 4.6.1 --- Spatial variation --- p.121 / Chapter 4.6.1.1 --- Spatial effect on bacterial abundance --- p.121 / Chapter 4.6.1.2 --- Spatial effect on species diversity --- p.121 / Chapter 4.6.2 --- Daily variation --- p.126 / Chapter 4.6.2.1 --- Daily effect on bacterial abundance --- p.126 / Chapter 4.6.2.2 --- Daily effect on species diversity --- p.126 / Chapter 4.6.3 --- Seasonal variation --- p.126 / Chapter 4.6.3.1 --- Seasonal effect on bacterial abundance --- p.126 / Chapter 4.6.3.2 --- Seasonal effect on species diversity --- p.130 / Chapter 4.7 --- Temperature effect on individual airborne bacterial population --- p.130 / Chapter 4.7.1 --- Gram positive bacteria --- p.130 / Chapter 4.7.2 --- Gram negative bacteria --- p.130 / Chapter 4.8 --- Effect of relative humidity on individual airborne bacterial population --- p.137 / Chapter 4.8.1 --- Gram positive bacteria --- p.137 / Chapter 4.8.2 --- Gram negative bacteria --- p.137 / Chapter 5 --- Discussion --- p.143 / Chapter 5.1 --- Bacterial profile --- p.143 / Chapter 5.1.1 --- Bacterial diversity --- p.143 / Chapter 5.1.2 --- Information of the identified bacteria from the student canteen --- p.144 / Chapter 5.1.3 --- Pathogenicity --- p.153 / Chapter 5.1.4 --- Summary on the bacterial profile --- p.153 / Chapter 5.2 --- Comparison between samples --- p.160 / Chapter 5.2.1 --- Spatial variation (Sampling point 1 against Sampling point 2) --- p.160 / Chapter 5.2.2 --- Daily variation (Morning against Afternoon) --- p.161 / Chapter 5.2.3 --- Seasonal variation --- p.162 / Chapter 5.2.4 --- Summer holiday against Summer school time --- p.163 / Chapter 5.2.5 --- Summary on the factors affecting the bacterial content --- p.164 / Chapter 5.3 --- Summary on indoor air quality of the student canteen in terms of bacterial level. --- p.166 / Chapter 6 --- Conclusions --- p.168 / Chapter 7 --- References --- p.169 / Appendix 1 --- p.183 / Appendix 2 --- p.187

Background: Indoor air contaminants generally have a greater impact on health than outdoor air contaminants, which increases the importance of a dependable, accessible, and minimally impactful method for measuring indoor air exchange rates. Objective: Evaluate the use of naturally generated CO2 as a tool to measure indoor ventilation. Methods: Indoor CO2 levels were measured over seven sample intervals in an airtight one-bedroom apartment with two residents. High frequency noise was removed from the measurements with Fourier, Kalman, LOESS, and rolling average filters. Root-mean squared errors (RMSE) between filtered and measured CO2 were calculated and compared for each sample interval and filter pair. A multivariable linear regression was used to assess differences between digital filters. Local minima and maxima were identified to calculate air exchange rates. The R statistical software was used for all data management and analysis. Results: The RMSE for all filter types had geometric standard deviations between one and two, indicating that all filters were stable across sample intervals. Results of the multivariable linear regression indicate that the RMSE of the Fourier filter were significantly lower than those of the Kalman filter with a P-value ofConclusions:The Fourier filter performed best based on visual analysis and RMSE comparisons. All filters except for the rolling average filter identified the majority of primary local minima/maxima effectively.

Large enterprises are often interested in tracking objects and people within buildings to improve resource allocation and occupant experience. Infrastructure-based indoor positioning systems (IIPS) can provide this service at low-cost by leveraging already deployed Wi-Fi infrastructure. Typically, IIPS perform localization and tracking of devices by measuring only Wi-Fi signals at wireless access points and do not rely on inertial sensor data at mobile devices (e.g., smartphones), which would require explicit user consent and sensing capabilities of the devices. Despite these advantages, building an economically viable cost-effective IIPS that can accurately and simultaneously track many devices over very large buildings is difficult due to three main challenges. First, Wi-Fi signal measurements are extremely noisy due to unpredictable multipath propagation and signal attenuation. Second, as the IIPS obtain measurements in a best effort manner without requiring any applications installed on a tracked device, the measurements are temporally sparse and non-periodic, which makes it difficult to exploit historical measurements. Third, the cost-effective IIPS have limited computational resources, in turn limiting scalability in terms of the number of simultaneously tracked devices. Prior approaches have narrowly focused on either improving the accuracy or reducing the complexity of localization algorithms. To compute the location at the current time step, they typically use only the latest explicit Wi-Fi measurements (e.g., signal strengths). The novelty of our approach lies in considering contexts of a device that can provide useful indications of the device's location. One such example of context is device motion. It indicates whether or not the device's location has changed. For a stationary device, the IIPS can either skip expensive device localization or aggregate noisy, temporally sparse location estimates to improve localization accuracy. Another example of context applicable to a moving device is a floor map that consists of pre-defined path segments that a user can take. The map can be leveraged to constrain noisy, temporally sparse location estimates on the paths. The thesis of this dissertation is that embedding context-aware capabilities in the IIPS enhances its performance in tracking many devices simultaneously and accurately. Specifically, we develop motion detection and map matching to show the benefits of leveraging two critical contexts: device motion and floor map. Providing motion detection and map matching is non-trivial in the IIPS where we must rely only on data from the Wi-Fi infrastructure. This thesis makes two contributions. First, we develop feature-based and deep learning-based motion detection models that exploit temporal patterns in Wi-Fi measurements across different access points to classify device motion in real time. Our extensive evaluations on datasets from real Wi-Fi deployments show that our motion detection models can detect device motion accurately. This, in turn, allows the IIPS to skip repeated location computation for stationary devices or improve the accuracy of localizing these devices. Second, we develop graph-based and image-based map matching models to exploit floor maps. The novelty of the graph-based approach lies in applying geometric and topological constraints to select which path segment to align the current location estimate. Our graph-based map matching can align a location estimate of a user device on the path taken by the user and close to the user's current location. The novelty of the image-based approach lies in representing for the first time, input data including location estimates and the floor map as 2D images. This novel representation enables the design, development, and application of encoder-decoder neural networks to exploit spatial relationships in input images to potentially improve location accuracy. In our evaluation, we show that the image-based approach can improve location accuracy with large simulated datasets, compared to the graph-based approach. Together, these contributions enable improvement of the IIPS in its ability to accurately and simultaneously track many devices over large buildings.

Office buildings in hot humid Singapore appear to be designed for stable and uniform indoor conditions. It is proposed in this thesis that this is unnecessary, as occupant comfort expectations do not warrant it and energy is wasted as a result. A comfort-based approach to design is advocated, as a means of balancing user needs with the objective of energy conservation.This issue of how perception of comfort is linked with indoor stability emerged from the question, 'why do office buildings, despite Bioclimatic prescriptions for hot humid conditions, continue to be predominantly climate rejecting and active-run?' The literature was found to be polarised by arguments for architectural solutions that are climatically responsive and present lower energy costs, and those for engineered solutions that deliver greater, more consistent comfort, albeit through reliance on electro-mechanical systems.It is argued that comprehending the gaps in the literature, and between theory and application, requires a better understanding of occupant comfort. This would be an inside-out view of comfort and climate, predicated on how the occupant is affected by the building and the cognitive nature of comfort itself.Relying on a sample of office buildings, the thesis set out to establish the following:Prevalence of the climate-based approach, specifically Yeang's Bioclimatic ModelPrevalence of uniformity and stability of the indoor environmentOccupant perception of indoor comfort, both thermal and visual, particularly with regard to variability of ambient conditionsOccupant perception of various operational modes: passive, mixed and activeThese goals were addressed through observations of form, envelope and layout, occupant surveys and the monitoring of buildings in passive and active modes.It was found that the Bioclimatic approach is non-existent in the context of the Singapore office ++ / building. In the case of two Bioclimatic buildings in Malaysia, the Model is not consistently applied. This disparity appears partly due to conflicting priorities, in particular style, cost and client pressures, and partly due to assumptions about occupant comfort.The Singapore office building was found to be predominantly active-run, operating within a narrow bandwidth of temperatures across most spaces. Occupant perception of variability outside the primary workplace, however, is one of acceptance, even preference. It was found through analysis of user feedback that the office building, on the basis of comfort expectations, could be divided into three activity zones: Work, Support and Transit.This 3-tiered structure was subsequently tested through a large-scale, longitudinal survey carried out across three spaces, each representing an activity zone, within a single building. The survey was accompanied by adjustments to the building's temperature settings to test the limits of acceptance in each zone. Findings from this exercise support the notion of a three-zoned office building, in which thermal conditions for each zone could be varied without affecting comfort. Energy figures that were monitored before and after the resetting showed drops of 7.1 % in chiller consumption and 2.9% in overall consumption.These findings led to a comfort-based, tri-modal proposal for office buildings in hot humid conditions, defined as the Psychoclimatic Model for its basis in comfort expectations and the interaction between climate, building and the occupant.The implications of the thesis outcome on regulatory control in Singapore and thermal comfort theory are discussed. Recommendations are made for future research into other building types and national context, plus a parametric study into the full energy-saving potential of the Psychoclimatic Model.