14,153 research outputs found
Risk Identification And Analysis Of Precast Concrete Structure Based On Work Breakdown Structure-Risk Breakdown Structure
Because the prefabricated building started late in China, and subject to management and technical restrictions, the safety problems during the construction of the prefabricated building have not been solved effectively. In view of the problems of complex environments in precast concrete structure and many influencing factors which makes the construction risks are difficult to identify. The work breakdown structure (WBS) - risk breakdown structure (RBS) method is introduced to solve the problem. By means of analyzing the investigation data of the prefabricated building accidents, its risks during construction are identified and coupled. Then the judgment matrix is obtained and the corresponding risk factors can be established. In the meanwhile, the fault tree analysis method has been being used to analyze the sensitivity of three kinds of accidents, such as falling, striking by object and electrocution. The sensitive coefficients of risk factors are calculated and sorted. The result shows that the main risk factors of falling accident are verticality deviation of component installation, deviation of component position and unsecured mechanics. The main risk factors of striking by object/equipment are insufficient strength of components supporting, overturning components and unreasonable of suspension point. The main risk factors of electrocution are improper welding operation and short circuit. Finally, corresponding control measures are put forward according to the risk accidents. The research results provided a good theoretical basis for the risk identification of prefabricated building construction
Influence of slope aspect on the microbial properties of rhizospheric and non-rhizospheric soils on the Loess Plateau, China
Slope aspect is an important topographic factor in the micro-ecosystem
environment, but its effect on the microbial properties of grassland
rhizospheric soil (RS) and non-rhizospheric soil (NRS) remain unclear. A
field experiment was conducted at the Ansai Research Station on the Loess
Plateau in China to test the influence of slope aspects (south-facing,
north-facing, and northwest-facing slopes, all with Artemisia
sacrorum as the dominant species) on RS and NRS microbial biomass carbon
(MBC) contents, phospholipid fatty acid (PLFA) contents, and the rhizospheric
effect (RE) of various microbial indices. Soil samples were collected from
the three slope aspects, including rhizospheric and non-rhizospheric region,
and analyzed to determine the various related microbial indices. The results
showed that MBC content differed significantly among the slope aspects in RS
but not in NRS, and the RE for MBC content in the south-facing slope was
larger than that in the north-facing slope. RS total, bacterial, and
Gram-positive bacterial PLFA contents in the south-facing slope were
significantly lower than those in the north- and northwest-facing slopes, and
RS Gram-negative bacterial (G−) and actinomycete PLFA contents in the
south-facing slope were significantly lower than those in the north-facing
slope. In contrast, NRS total, bacterial, and G− PLFA contents in the
north-facing slope were significantly higher than those in the south- and
northwest-facing slopes, and NRS fungal and actinomycete PLFA contents in the
north- and south-facing slopes were significantly higher than those in the
northwest-facing slope. RE for all PLFA contents except fungal in the
northwest-facing slope were higher than those in the south-facing slope.
Slope aspect significantly but differentially affected the microbial
properties in RS and NRS, and the variable influence was due to an evident RE
for most microbial properties.</p
Cooperative Control for Target Tracking with Onboard Sensing
Abstract We consider the cooperative control of a team of robots to estimate the position of a moving target using onboard sensing. In particular, we do not as-sume that the robot positions are known, but estimate their positions using relative onboard sensing. Our probabilistic localization and control method takes into ac-count the motion and sensing capabilities of the individual robots to minimize the expected future uncertainty of the target position. It reasons about multiple possi-ble sensing topologies and incorporates an efficient topology switching technique to generate locally optimal controls in polynomial time complexity. Simulations show the performance of our approach and prove its flexibility to find suitable sensing topologies depending on the limited sensing capabilities of the robots and the movements of the target. Furthermore, we demonstrate the applicability of our method in various experiments with single and multiple quadrotor robots tracking a ground vehicle in an indoor environment
Exact ground states for the four-electron problem in a Hubbard ladder
The exact ground state of four electrons in an arbitrary large two leg
Hubbard ladder is deduced from nine analytic and explicit linear equations. The
used procedure is described, and the properties of the ground state are
analyzed. The method is based on the construction in r-space of the different
type of orthogonal basis wave vectors which span the subspace of the Hilbert
space containing the ground state. In order to do this, we start from the
possible microconfigurations of the four particles within the system. These
microconfigurations are then rotated, translated and spin-reversed in order to
build up the basis vectors of the problem. A closed system of nine analytic
linear equations is obtained whose secular equation, by its minimum energy
solution, provides the ground state energy and the ground state wave function
of the model.Comment: 10 pages, 7 figure
Approximations from Anywhere and General Rough Sets
Not all approximations arise from information systems. The problem of fitting
approximations, subjected to some rules (and related data), to information
systems in a rough scheme of things is known as the \emph{inverse problem}. The
inverse problem is more general than the duality (or abstract representation)
problems and was introduced by the present author in her earlier papers. From
the practical perspective, a few (as opposed to one) theoretical frameworks may
be suitable for formulating the problem itself. \emph{Granular operator spaces}
have been recently introduced and investigated by the present author in her
recent work in the context of antichain based and dialectical semantics for
general rough sets. The nature of the inverse problem is examined from
number-theoretic and combinatorial perspectives in a higher order variant of
granular operator spaces and some necessary conditions are proved. The results
and the novel approach would be useful in a number of unsupervised and semi
supervised learning contexts and algorithms.Comment: 20 Pages. Scheduled to appear in IJCRS'2017 LNCS Proceedings,
Springe
VANISHING POINT AIDED LANE DETECTION USING A MULTI-SENSOR SYSTEM
Lane Detection is a critical component of an autonomous driving system that can be integrated alongside with High-definition (HD) map to improve accuracy and reliability of the system. Typically, lane detection is achieved using computer vision algorithms such as edge detection and Hough transform, deep learning-based algorithms, or motion-based algorithms to detect and track the lanes on the road. However, these approaches can contain incorrectly detected line segments with outliers. To address these issues, we proposed a vanishing point aided lane detection method that utilizes both camera and LiDAR sensors, and then employs a RANSAC-based post-processing method to remove potential outliers to improve the accuracy of the detected lanes. We evaluated this method on four datasets provided from the KITTI Benchmark Suite and achieved a total precision of 87%
Factorization Properties of Soft Graviton Amplitudes
We apply recently developed path integral resummation methods to perturbative
quantum gravity. In particular, we provide supporting evidence that eikonal
graviton amplitudes factorize into hard and soft parts, and confirm a recent
hypothesis that soft gravitons are modelled by vacuum expectation values of
products of certain Wilson line operators, which differ for massless and
massive particles. We also investigate terms which break this factorization,
and find that they are subleading with respect to the eikonal amplitude. The
results may help in understanding the connections between gravity and gauge
theories in more detail, as well as in studying gravitational radiation beyond
the eikonal approximation.Comment: 35 pages, 5 figure
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