1,066 research outputs found
Object Tracking in Vary Lighting Conditions for Fog based Intelligent Surveillance of Public Spaces
With rapid development of computer vision and artificial intelligence, cities are becoming more and more intelligent. Recently, since intelligent surveillance was applied in all kind of smart city services, object tracking attracted more attention. However, two serious problems blocked development of visual tracking in real applications. The first problem is its lower performance under intense illumination variation while the second issue is its slow speed. This paper addressed these two problems by proposing a correlation filter based tracker. Fog computing platform was deployed to accelerate the proposed tracking approach. The tracker was constructed by multiple positions' detections and alternate templates (MPAT). The detection position was repositioned according to the estimated speed of target by optical flow method, and the alternate template was stored with a template update mechanism, which were all computed at the edge. Experimental results on large-scale public benchmark datasets showed the effectiveness of the proposed method in comparison with state-of-the-art methods
Waveform Design for Maximum Pass-Band Energy
One way to maximize the sensitivity of an ultrasonic inspection is by establishing the pulser output voltage waveform to provide the maximum possible fraction of its energy in the pass-band of the piezoelectric transducer. An analytical study is reported that is backed up with experimental verification. Two pulser constraints are analyzed in this study. The first constraint is to study the common and easily generated waveform shapes for which each waveform has unit energy and compare to the optimum waveform shape with unit energy that is determined analytically. The second constraint is to repeat the first analysis with waveforms having unit amplitude rather than unit energy. The analysis for the first constraint shows that the numerically intractable problem of summing a very large number of Fourier coefficients can be replaced by a mathematically equivalent evaluation of the pass-band energy which requires only the integration of smooth functions. This alternative formulation also leads to the result that the optimized waveform is the eigenfunction of a particular integral operator corresponding to the largest eigenvalue. The eigenvalue itself gives the maximum attainable passband energy. The optimized waveform is compared with sine waves, rectangular waves, trapezoidal waves, triangle waves and exponential spikes for 1/2, 1 and 3/2 cycle durations. The analysis for the second constraint shows that the unit amplitude is in the form of an inequality which is outside the realm of the classical calculus of variations. An exact characterization of the optimized waveform was not found but numerical integration techniques were employed to determine the pass-band energies for the waveforms considered under the first constraint. Finally, a breadboard pulser model is constructed and extensive comparisons of the various waveshapes, sensitivity studies, spectral distributions and experimental verification are made for each constraint
Development of IoT Smart Greenhouse System for Hydroponic Gardens
This study focused on the development of a smart greenhouse system for
hydroponic gardens with the adaptation of the Internet of Things and monitored
through mobile as one of the solutions towards the negative effects of the
worlds booming population, never ending - shrinking of arable lands, and the
effect of climate change drastically in our environments. To achieve the goal
of the study, the researchers created an actual hydroponic greenhouse system
with completely developing plants, and automation in examining and monitoring
the water pH level, light, water, and greenhouse temperature, as well as
humidity which is linked to ThingSpeak. The developed SMART Greenhouse
monitoring system was tested and evaluated to confirm its reliability,
functions, and usability under ISO 9126 evaluation criteria. The respondents
who include casual plant owners and experts in hydroponic gardening able to
test and evaluate the prototype, and the mobile application to monitor the
parameters with the results of 7.77 for pH level, 83 for light, 27.94 deg C for
water temperature, 27 deg C for greenhouse temperature, and 75% for humidity
with a descriptive result in both software and hardware as Very Good with a
mean average of 4.06 which means that the developed technology is useful and
recommended. The SMART Greenhouse System for Hydroponic Garden is used as an
alternative tool, solution, and innovation technique towards food shortages due
to climate change, land shortages, and low farming environments. The proponents
highly suggest the use of solar energy for the pump power, prototype wiring
should be improved, the usage of a high-end model of Arduino to address more
sensors and devices for a larger arsenal of data collected, enclosures of the
device to ensure safety, and mobile application updates such as bug fixes and
have an e-manual of the whole systems
Cues and knowledge structures used by mental-health professionals when making risk assessments
Background: Research into mental-health risks has tended to focus on epidemiological approaches and to consider pieces of evidence in isolation. Less is known about the particular
factors and their patterns of occurrence that influence cliniciansâ risk judgements in practice.
Aims: To identify the cues used by clinicians to make risk judgements and to explore how these combine within cliniciansâ psychological representations of suicide, self-harm, self-neglect, and harm to others.
Method: Content analysis was applied to semi-structured interviews conducted with 46 practitioners from various mental-health disciplines, using mind maps to represent the
hierarchical relationships of data and concepts.
Results: Strong consensus between experts meant their knowledge could be integrated into a single hierarchical structure for each risk. This revealed contrasting emphases between data and concepts underpinning risks, including: reflection and forethought for suicide; motivation
for self-harm; situation and context for harm to others; and current presentation for self-neglect.
Conclusions: Analysis of expertsâ risk-assessment knowledge identified influential cues and their relationships to risks. It can inform development of valid risk-screening decision support systems that combine actuarial evidence with clinical expertise
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Fabrication Flaw Density and Distribution In Repairs to Reactor Pressure Vessel and Piping Welds
The Pacific Northwest National Laboratory is developing a generalized fabrication flaw distribution for the population of nuclear reactor pressure vessels and for piping welds in U.S. operating reactors. The purpose of the generalized flaw distribution is to predict component-specific flaw densities. The estimates of fabrication flaws are intended for use in fracture mechanics structural integrity assessments. Structural integrity assessments, such as estimating the frequency of loss-of-coolant accidents, are performed by computer codes that require, as input, accurate estimates of flaw densities. Welds from four different reactor pressure vessels and a collection of archived pipes have been studied to develop empirical estimates of fabrication flaw densities. This report describes the fabrication flaw distribution and characterization in the repair weld metal of vessels and piping. This work indicates that large flaws occur in these repairs. These results show that repair flaws are complex in composition and sometimes include cracks on the ends of the repair cavities. Parametric analysis using an exponential fit is performed on the data. The relevance of construction records is established for describing fabrication processes and product forms. An analysis of these records shows there was a significant change in repair frequency over the years when these components were fabricated. A description of repair flaw morphology is provided with a discussion of fracture mechanics significance. Fabrication flaws in repairs are characterized using optimized-access, high-sensitivity nondestructive ultrasonic testing. Flaw characterizations are then validated by other nondestructive evaluation techniques and complemented by destructive testing
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. V. Rising X-ray Emission from an Off-Axis Jet
We report the discovery of rising X-ray emission from the binary neutron star
(BNS) merger event GW170817. This is the first detection of X-ray emission from
a gravitational-wave source. Observations acquired with the Chandra X-ray
Observatory (CXO) at t~2.3 days post merger reveal no significant emission,
with L_x<=3.2x10^38 erg/s (isotropic-equivalent). Continued monitoring revealed
the presence of an X-ray source that brightened with time, reaching L_x\sim
9x10^39 erg/s at ~15.1 days post merger. We interpret these findings in the
context of isotropic and collimated relativistic outflows (both on- and
off-axis). We find that the broad-band X-ray to radio observations are
consistent with emission from a relativistic jet with kinetic energy
E_k~10^49-10^50 erg, viewed off-axis with theta_obs~ 20-40 deg. Our models
favor a circumbinary density n~ 0.0001-0.01 cm-3, depending on the value of the
microphysical parameter epsilon_B=10^{-4}-10^{-2}. A central-engine origin of
the X-ray emission is unlikely. Future X-ray observations at
days, when the target will be observable again with the CXO, will provide
additional constraints to solve the model degeneracies and test our
predictions. Our inferences on theta_obs are testable with gravitational wave
information on GW170817 from Advanced LIGO/Virgo on the binary inclination.Comment: 7 Pages, 4 Figures, ApJL, In Press. Keywords: GW170817, LV
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale
We present the properties of NGC 4993, the host galaxy of GW170817, the first
gravitational wave (GW) event from the merger of a binary neutron star (BNS)
system and the first with an electromagnetic (EM) counterpart. We use both
archival photometry and new optical/near-IR imaging and spectroscopy, together
with stellar population synthesis models to infer the global properties of the
host galaxy. We infer a star formation history peaked at Gyr ago,
with subsequent exponential decline leading to a low current star formation
rate of 0.01 M yr, which we convert into a binary merger
timescale probability distribution. We find a median merger timescale of
Gyr, with a 90% confidence range of Gyr. This
in turn indicates an initial binary separation of R,
comparable to the inferred values for Galactic BNS systems. We also use new and
archival images to measure a projected offset of
the optical counterpart of kpc (0.64) from the center of NGC 4993
and to place a limit of mag on any pre-existing emission,
which rules out the brighter half of the globular cluster luminosity function.
Finally, the age and offset of the system indicates it experienced a modest
natal kick with an upper limit of km s. Future GWEM
observations of BNS mergers will enable measurement of their population delay
time distribution, which will directly inform their viability as the dominant
source of -process enrichment in the Universe.Comment: 9 Pages, 3 Figures, 2 Tables, ApJL, In Press. Keywords: GW170817, LV
Design implications for task-specific search utilities for retrieval and re-engineering of code
The importance of information retrieval systems is unquestionable in the modern society and both individuals as well as enterprises recognise the benefits of being able to find information effectively. Current code-focused information retrieval systems such as Google Code Search, Codeplex or Koders produce results based on specific keywords. However, these systems do not take into account developersâ context such as development language, technology framework, goal of the project, project complexity and developerâs domain expertise. They also impose additional cognitive burden on users in switching between different interfaces and clicking through to find the relevant code. Hence, they are not used by software developers. In this paper, we discuss how software engineers interact with information and general-purpose information retrieval systems (e.g. Google, Yahoo!) and investigate to what extent domain-specific search and recommendation utilities can be developed in order to support their work-related activities. In order to investigate this, we conducted a user study and found that software engineers followed many identifiable and repeatable work tasks and behaviours. These behaviours can be used to develop implicit relevance feedback-based systems based on the observed retention actions. Moreover, we discuss the implications for the development of task-specific search and collaborative recommendation utilities embedded with the Google standard search engine and Microsoft IntelliSense for retrieval and re-engineering of code. Based on implicit relevance feedback, we have implemented a prototype of the proposed collaborative recommendation system, which was evaluated in a controlled environment simulating the real-world situation of professional software engineers. The evaluation has achieved promising initial results on the precision and recall performance of the system
Some Aspects of Cost/ Benefit Analysis for In-Service Inspection of PWR Steam Generators
This report discusses a number of aspects of cost/benefit (C/B) analysis for in-service inspection (lSI} of pressurized water reactor (PWR) steam generators (SGs) and identifies several problem areas that must be addressed prior to a full C/B analysis capability. Following a brief review of the impact of SG problems on the productivity of PWR units and of the scope and variability of SG problems among U.S. PWRs, various occupational implications of SG lSI are considered, namely manpower, time, and rad exposure. The opportunities provided by refueling outages in respect to lSI frequency and work time windows are reviewed. Indices for characterizing the nondestructive testing {NDT) information, rad exposure, impact of unscheduled outages attributable to SG problems with the cost is virtually negligible for well-planned ISis. Considering the ALARA constraint on occupational rad exposure, the skilled manpower pool for NDT work appears to be the principal factor limiting lSI scope and frequency. Analysis of the manpower and time requirements for inspection of a 40-unit PWR population indicates, however, that an lSI strategy embodying two campaigns per year and a total population inspection within a 2-year interval is not far beyond current capabilities
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Real-time 3-D SAFT-UT system evaluation and validation
SAFT-UT technology is shown to provide significant enhancements to the inspection of materials used in US nuclear power plants. This report provides guidelines for the implementation of SAFT-UT technology and shows the results from its application. An overview of the development of SAFT-UT is provided so that the reader may become familiar with the technology. Then the basic fundamentals are presented with an extensive list of references. A comprehensive operating procedure, which is used in conjunction with the SAFT-UT field system developed by Pacific Northwest Laboratory (PNL), provides the recipe for both SAFT data acquisition and analysis. The specification for the hardware implementation is provided for the SAFT-UT system along with a description of the subsequent developments and improvements. One development of technical interest is the SAFT real time processor. Performance of the real-time processor is impressive and comparison is made of this dedicated parallel processor to a conventional computer and to the newer high-speed computer architectures designed for image processing. Descriptions of other improvements, including a robotic scanner, are provided. Laboratory parametric and application studies, performed by PNL and not previously reported, are discussed followed by a section on field application work in which SAFT was used during inservice inspections of operating reactors
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