101 research outputs found
Attack Detection in Sensor Network Target Localization Systems with Quantized Data
We consider a sensor network focused on target localization, where sensors
measure the signal strength emitted from the target. Each measurement is
quantized to one bit and sent to the fusion center. A general attack is
considered at some sensors that attempts to cause the fusion center to produce
an inaccurate estimation of the target location with a large mean-square-error.
The attack is a combination of man-in-the-middle, hacking, and spoofing attacks
that can effectively change both signals going into and coming out of the
sensor nodes in a realistic manner. We show that the essential effect of
attacks is to alter the estimated distance between the target and each attacked
sensor to a different extent, giving rise to a geometric inconsistency among
the attacked and unattacked sensors. Hence, with the help of two secure
sensors, a class of detectors are proposed to detect the attacked sensors by
scrutinizing the existence of the geometric inconsistency. We show that the
false alarm and miss probabilities of the proposed detectors decrease
exponentially as the number of measurement samples increases, which implies
that for sufficiently large number of samples, the proposed detectors can
identify the attacked and unattacked sensors with any required accuracy
Design considerations for a heterogeneous network of bearings-only sensors using sensor management
This paper presents a design characterization of heterogeneous sensor networks with the goal of geolocation accuracy. It is assumed that the network exploits sensor management to conserve node power usage. We focus on bearings-only sensor networks consisting of acoustic and imaging modalities. Each available node modality is a bearings-only sensor of varying capability. The optimal mixture of modalities is discussed under the constraint of the overall network cost. Finally, simulations verify the theory and demonstrate design choices
Knowledge from Uncertainty in Evidential Deep Learning
This work reveals an evidential signal that emerges from the uncertainty
value in Evidential Deep Learning (EDL). EDL is one example of a class of
uncertainty-aware deep learning approaches designed to provide confidence (or
epistemic uncertainty) about the current test sample. In particular for
computer vision and bidirectional encoder large language models, the
`evidential signal' arising from the Dirichlet strength in EDL can, in some
cases, discriminate between classes, which is particularly strong when using
large language models. We hypothesise that the KL regularisation term causes
EDL to couple aleatoric and epistemic uncertainty. In this paper, we
empirically investigate the correlations between misclassification and
evaluated uncertainty, and show that EDL's `evidential signal' is due to
misclassification bias. We critically evaluate EDL with other Dirichlet-based
approaches, namely Generative Evidential Neural Networks (EDL-GEN) and Prior
Networks, and show theoretically and empirically the differences between these
loss functions. We conclude that EDL's coupling of uncertainty arises from
these differences due to the use (or lack) of out-of-distribution samples
during training
PPO-UE: Proximal Policy Optimization via Uncertainty-Aware Exploration
Proximal Policy Optimization (PPO) is a highly popular policy-based deep
reinforcement learning (DRL) approach. However, we observe that the homogeneous
exploration process in PPO could cause an unexpected stability issue in the
training phase. To address this issue, we propose PPO-UE, a PPO variant
equipped with self-adaptive uncertainty-aware explorations (UEs) based on a
ratio uncertainty level. The proposed PPO-UE is designed to improve convergence
speed and performance with an optimized ratio uncertainty level. Through
extensive sensitivity analysis by varying the ratio uncertainty level, our
proposed PPO-UE considerably outperforms the baseline PPO in Roboschool
continuous control tasks
Influence of Role Models and Hospital Design on the Hand Hygiene of Health-Care Workers
We assessed the effect of medical staff role models and the number of health-care worker sinks on hand-hygiene compliance before and after construction of a new hospital designed for increased access to handwashing sinks. We observed health-care worker hand hygiene in four nursing units that provided similar patient care in both the old and new hospitals: medical and surgical intensive care, hematology/oncology, and solid organ transplant units. Of 721 hand-hygiene opportunities, 304 (42%) were observed in the old hospital and 417 (58%) in the new hospital. Hand-hygiene compliance was significantly better in the old hospital (161/304; 53%) compared to the new hospital (97/417; 23.3%) (p<0.001). Health-care workers in a room with a senior (e.g., higher ranking) medical staff person or peer who did not wash hands were significantly less likely to wash their own hands (odds ratio 0.2; confidence interval 0.1 to 0.5); p<0.001). Our results suggest that health-care worker hand-hygiene compliance is influenced significantly by the behavior of other health-care workers. An increased number of hand-washing sinks, as a sole measure, did not increase hand-hygiene compliance
Clinical decision-making: physicians' preferences and experiences
BACKGROUND: Shared decision-making has been advocated; however there are relatively few studies on physician preferences for, and experiences of, different styles of clinical decision-making as most research has focused on patient preferences and experiences. The objectives of this study were to determine 1) physician preferences for different styles of clinical decision-making; 2) styles of clinical decision-making physicians perceive themselves as practicing; and 3) the congruence between preferred and perceived style. In addition we sought to determine physician perceptions of the availability of time in visits, and their role in encouraging patients to look for health information. METHODS: Cross-sectional survey of a nationally representative sample of U.S. physicians. RESULTS: 1,050 (53% response rate) physicians responded to the survey. Of these, 780 (75%) preferred to share decision-making with their patients, 142 (14%) preferred paternalism, and 118 (11%) preferred consumerism. 87% of physicians perceived themselves as practicing their preferred style. Physicians who preferred their patients to play an active role in decision-making were more likely to report encouraging patients to look for information, and to report having enough time in visits. CONCLUSION: Physicians tend to perceive themselves as practicing their preferred role in clinical decision-making. The direction of the association cannot be inferred from these data; however, we suggest that interventions aimed at promoting shared decision-making need to target physicians as well as patients
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