53,831 research outputs found
Effects of Antenna Beam Chromaticity on Redshifted 21~cm Power Spectrum and Implications for Hydrogen Epoch of Reionization Array
Unaccounted for systematics from foregrounds and instruments can severely
limit the sensitivity of current experiments from detecting redshifted 21~cm
signals from the Epoch of Reionization (EoR). Upcoming experiments are faced
with a challenge to deliver more collecting area per antenna element without
degrading the data with systematics. This paper and its companions show that
dishes are viable for achieving this balance using the Hydrogen Epoch of
Reionization Array (HERA) as an example. Here, we specifically identify
spectral systematics associated with the antenna power pattern as a significant
detriment to all EoR experiments which causes the already bright foreground
power to leak well beyond ideal limits and contaminate the otherwise clean EoR
signal modes. A primary source of this chromaticity is reflections in the
antenna-feed assembly and between structures in neighboring antennas. Using
precise foreground simulations taking wide-field effects into account, we
provide a framework to set cosmologically-motivated design specifications on
these reflections to prevent further EoR signal degradation. We show HERA will
not be impeded by such spectral systematics and demonstrate that even in a
conservative scenario that does not perform removal of foregrounds, HERA will
detect EoR signal in line-of-sight -modes, ~Mpc, with high significance. All baselines in a 19-element HERA
layout are capable of detecting EoR over a substantial observing window on the
sky.Comment: 11 pages, 6 figures (10 total including subfigures), submitted to Ap
Foreign Object Detection and Quantification of Fat Content Using A Novel Multiplexing Electric Field Sensor
There is an ever growing need to ensure the quality of food and assess
specific quality parameters in all the links of the food chain, ranging from
processing, distribution and retail to preparing food. Various imaging and
sensing technologies, including X-ray imaging, ultrasound, and near infrared
reflectance spectroscopy have been applied to the problem. Cost and other
constraints restrict the application of some of these technologies. In this
study we test a novel Multiplexing Electric Field Sensor (MEFS), an approach
that allows for a completely non-invasive and non-destructive testing approach.
Our experiments demonstrate the reliable detection of certain foreign objects
and provide evidence that this sensor technology has the capability of
measuring fat content in minced meat. Given the fact that this technology can
already be deployed at very low cost, low maintenance and in various different
form factors, we conclude that this type of MEFS is an extremely promising
technology for addressing specific food quality issues
Construction safety and digital design: a review
As digital technologies become widely used in designing buildings and infrastructure, questions arise about
their impacts on construction safety. This review explores relationships between construction safety and
digital design practices with the aim of fostering and directing further research. It surveys state-of-the-art
research on databases, virtual reality, geographic information systems, 4D CAD, building information
modeling and sensing technologies, finding various digital tools for addressing safety issues in the
construction phase, but few tools to support design for construction safety. It also considers a literature on
safety critical, digital and design practices that raises a general concern about ‘mindlessness’ in the use of
technologies, and has implications for the emerging research agenda around construction safety and digital
design. Bringing these strands of literature together suggests new kinds of interventions, such as the
development of tools and processes for using digital models to promote mindfulness through multi-party
collaboration on safet
Greater understanding of spacing needs for children’s eye movements during on-screen reading is required
This paper endeavors to consolidate current knowledge and empirical research concerning the use of typography for children’s on-screen reading. This paper is not intended as a full literature review, but attempts to raise awareness of the areas required for future investigation. This evaluation indicates a significant gap in the literature of children’s on-screen reading and proposes a need for further investigations in typographical spacing. These future studies need to objectively consider children’s eye movements and the effect of screen based text presentation on children’s comprehension
An agent-based model of jaguar movement through conservation corridors
Wildlife corridors mitigate against habitat fragmentation by connecting otherwise isolated regions, bringing well established benefits to conservation both in principle and practice. Populations of large mammals in particular may depend on habitat connectivity, yet conservation managers struggle to optimise corridor designs with the rudimentary information generally available on movement behaviours. We present an agent-based model of jaguars (Panthera onca), scaled for fragmented habitat in Belize where proposals already exist for creating a jaguar corridor. We use a leastcost approach to simulate movement paths through alternative possible landscapes. Six different types of corridor and three control conditions differ substantially in their effectiveness at mixing agents across the environment despite relatively little difference in individual welfare. Our best estimates of jaguar movement behaviours suggest that a set of five narrow corridors may out-perform one wide corridor of the same overall area. We discuss the utility of ALife modelling for conservation management
Nonstimulated early visual areas carry information about surrounding context
Even within the early sensory areas, the majority of the input to any given cortical neuron comes from other cortical neurons. To extend our knowledge of the contextual information that is transmitted by such lateral and feedback connections, we investigated how visually nonstimulated regions in primary visual cortex (V1) and visual area V2 are influenced by the surrounding context. We used functional magnetic resonance imaging (fMRI) and pattern-classification methods to show that the cortical representation of a nonstimulated quarter-field carries information that can discriminate the surrounding visual context. We show further that the activity patterns in these regions are significantly related to those observed with feed-forward stimulation and that these effects are driven primarily by V1. These results thus demonstrate that visual context strongly influences early visual areas even in the absence of differential feed-forward thalamic stimulation
Reviewing the understanding of the effects of spacing on children’s eye movements for on-screen reading
This paper endeavors to consolidate current knowledge and empirical research concerning the use of typography for children’s on-screen reading. This paper is not intended as a full literature review but attempts to raise awareness of the areas required for future investigation. This evaluation indicates a significant gap in the literature of children’s on-screen reading and proposes a need for further investigations in typographical spacing. These future studies need to objectively consider children’s eye movements and the effect of screen based text presentation on children’s comprehension
Creation and detection of hardware trojans using non-invasive off-the-shelf technologies
As a result of the globalisation of the semiconductor design and fabrication processes, integrated circuits are becoming increasingly vulnerable to malicious attacks. The most concerning threats are hardware trojans. A hardware trojan is a malicious inclusion or alteration to the existing design of an integrated circuit, with the possible effects ranging from leakage of sensitive information to the complete destruction of the integrated circuit itself. While the majority of existing detection schemes focus on test-time, they all require expensive methodologies to detect hardware trojans. Off-the-shelf approaches have often been overlooked due to limited hardware resources and detection accuracy. With the advances in technologies and the democratisation of open-source hardware, however, these tools enable the detection of hardware trojans at reduced costs during or after production. In this manuscript, a hardware trojan is created and emulated on a consumer FPGA board. The experiments to detect the trojan in a dormant and active state are made using off-the-shelf technologies taking advantage of different techniques such as Power Analysis Reports, Side Channel Analysis and Thermal Measurements. Furthermore, multiple attempts to detect the trojan are demonstrated and benchmarked. Our simulations result in a state-of-the-art methodology to accurately detect the trojan in both dormant and active states using off-the-shelf hardware
- …