610 research outputs found
Spring search algorithm for simultaneous placement of distributed generation and capacitors
Purpose. In this paper, for simultaneous placement of distributed generation (DG) and capacitors, a new approach based on Spring Search Algorithm (SSA), is presented. This method is contained two stages using two sensitive index Sv and Ss. Sv and Ss are calculated according to nominal voltageand network losses. In the first stage, candidate buses are determined for installation DG and capacitors according to Sv and Ss. Then in the second stage, placement and sizing of distributed generation and capacitors are specified using SSA. The spring search algorithm is among the optimization algorithms developed by the idea of laws of nature and the search factors are a set of objects. The proposed algorithm is tested on 33-bus and 69-bus radial distribution networks. The test results indicate good performance of the proposed methodЦель. В статье для одновременного размещения распределенной генерации и конденсаторов представлен новый подход, основанный на "пружинном" алгоритме поиска (Spring Search Algorithm, SSA). Данный метод состоит из двух этапов с использованием двух показателей чувствительности Sv и Ss. Показатели чувствительности Sv и Ss рассчитываются в соответствии с номинальным напряжением и потерями в сети. На первом этапе определяются шины-кандидаты для установки распределенной генерации и конденсаторов согласно Sv и Ss. Затем, на втором этапе размещение и калибровка распределенной генерации и конденсаторов выполняются с использованием алгоритма SSA. "Пружинный" алгоритм поиска входит в число алгоритмов оптимизации, разработанных на основе идей законов природы, а факторы поиска представляют собой набор объектов. Предлагаемый алгоритм тестируется на радиальных распределительных сетях с 33 и 69 шинами. Результаты тестирования показывают хорошую эффективность предложенного метода
Video Data Compression by Progressive Iterative Approximation
In the present paper, the B-spline curve is used for reducing the entropy of video data. We consider the color or luminance variations of a spatial position in a series of frames as input data points in Euclidean space R or R3. The progressive and iterative approximation (PIA) method is a direct and intuitive way of generating curve series of high and higher fitting accuracy. The video data points are approximated using progressive and iterative approximation for least square (LSPIA) fitting. The Lossless video data compression is done through storing the B-spline curve control points (CPs) and the difference between fitted and original video data. The proposed method is applied to two classes of synthetically produced and naturally recorded video sequences and makes a reduction in the entropy of both. However, this reduction is higher for syntactically created than those naturally produced. The comparative analysis of experiments on a variety of video sequences suggests that the entropy of output video data is much less than that of input video data
Phase mixing of standing Alfven waves with shear flows in solar spicules
Alfvenic waves are thought to play an important role in coronal heating and
solar wind acceleration. Here we investigate the dissipation of such waves due
to phase mixing at the presence of shear flow and field in the stratified
atmosphere of solar spicules. The initial flow is assumed to be directed along
spicule axis and to vary linearly in the x direction and the equilibrium
magnetic field is taken 2-dimensional and divergence-free. It is determined
that the shear flow and field can fasten the damping of standing Alfven waves.
In spite of propagating Alfven waves, standing Alfven waves in Solar spicules
dissipate in a few periods. As height increases, the perturbed velocity
amplitude does increase in contrast to the behavior of perturbed magnetic
field. Moreover, it should be emphasized that the stratification due to
gravity, shear flow and field are the facts that should be considered in MHD
models in spicules.Comment: Accepted for publication in Astrophysics & Space Scienc
Two-Photon Spectroscopy of the NaLi Triplet Ground State
We employ two-photon spectroscopy to study the vibrational states of the
triplet ground state potential () of the NaLi
molecule. Pairs of Na and Li atoms in an ultracold mixture are photoassociated
into an excited triplet molecular state, which in turn is coupled to
vibrational states of the triplet ground potential. Vibrational state binding
energies, line strengths, and potential fitting parameters for the triplet
ground potential are reported. We also observe rotational
splitting in the lowest vibrational state.Comment: 7 pages, 3 figure
Solving an Optimal Control Problem of Cancer Treatment by Artificial Neural Networks
Cancer is an uncontrollable growth of abnormal cells in any tissue of the body. Many researchers have focused on machine learning and artificial intelligence (AI) based on approaches for cancer treatment. Dissimilar to traditional methods, these approaches are efficient and are able to find the optimal solutions of cancer chemotherapy problems. In this paper, a system of ordinary differential equations (ODEs) with the state variables of immune cells, tumor cells, healthy cells and drug concentration is proposed to anticipate the tumor growth and to show their interactions in the body. Then, an artificial neural network (ANN) is applied to solve the ODEs system through minimizing the error function and modifying the parameters consisting of weights and biases. The mean square errors (MSEs) between the analytical and ANN results corresponding to four state variables are 1.54e-06, 6.43e-07, 6.61e-06, and 3.99e-07, respectively. These results show the good performance and efficiency of the proposed method. Moreover, the optimal dose of chemotherapy drug and the amount of drug needed to continue the treatment process are achieved
Computing Local Sensitivities of Counting Queries with Joins
Local sensitivity of a query Q given a database instance D, i.e. how much the
output Q(D) changes when a tuple is added to D or deleted from D, has many
applications including query analysis, outlier detection, and in differential
privacy. However, it is NP-hard to find local sensitivity of a conjunctive
query in terms of the size of the query, even for the class of acyclic queries.
Although the complexity is polynomial when the query size is fixed, the naive
algorithms are not efficient for large databases and queries involving multiple
joins. In this paper, we present a novel approach to compute local sensitivity
of counting queries involving join operations by tracking and summarizing tuple
sensitivities -- the maximum change a tuple can cause in the query result when
it is added or removed. We give algorithms for the sensitivity problem for full
acyclic join queries using join trees, that run in polynomial time in both the
size of the database and query for an interesting sub-class of queries, which
we call 'doubly acyclic queries' that include path queries, and in polynomial
time in combined complexity when the maximum degree in the join tree is
bounded. Our algorithms can be extended to certain non-acyclic queries using
generalized hypertree decompositions. We evaluate our approach experimentally,
and show applications of our algorithms to obtain better results for
differential privacy by orders of magnitude.Comment: To be published in Proceedings of the 2020 ACM SIGMOD International
Conference on Management of Dat
Long-Lived Ultracold Molecules with Electric and Magnetic Dipole Moments
We create fermionic dipolar NaLi molecules in their triplet ground
state from an ultracold mixture of Na and Li. Using
magneto-association across a narrow Feshbach resonance followed by a two-photon
STIRAP transfer to the triplet ground state, we produce
ground state molecules in a spin-polarized state. We observe a lifetime of
in an isolated molecular sample, approaching the -wave
universal rate limit. Electron spin resonance spectroscopy of the triplet state
was used to determine the hyperfine structure of this previously unobserved
molecular state.Comment: 5 pages, 5 figure
Nitrate and nitrite accumulation in tomato and potato in Ardabil province
The research was conducted to determine the residual nitrite and nitrate on potatoes and tomatoes, two
commercially important vegetables in Ardabil province. Samples of these plants were collected randomly from
farms and wholesale markets in 10 day intervals at harvesting time in three sites (Ardabil, Parsabad and
Meshkin Shahr) during 2004 and 2005. The samples were analyzed for residual nitrate and nitrite using
spectroscopic method. The results revealed that in 10% of potato samples nitrate concentration was more than
acceptable level (465 – 519.3 mg/kg fresh weight). Nitrite residue in potatoes ranged from 0.1 to 1.12 mg/kg.
The nitrite and nitrate concentrations of 83.4% and 33% of tomato samples were lower than detecting limit of
the methods. The amount of nitrate in tomato samples of Meshghin shahr was 20 fold lowers than Parsabads
region that probably resulted from higher nitrogen fertilizers application in this region
LOCUS: A Multi-Sensor Lidar-Centric Solution for High-Precision Odometry and 3D Mapping in Real-Time
A reliable odometry source is a prerequisite to enable complex autonomy
behaviour in next-generation robots operating in extreme environments. In this
work, we present a high-precision lidar odometry system to achieve robust and
real-time operation under challenging perceptual conditions. LOCUS (Lidar
Odometry for Consistent operation in Uncertain Settings), provides an accurate
multi-stage scan matching unit equipped with an health-aware sensor integration
module for seamless fusion of additional sensing modalities. We evaluate the
performance of the proposed system against state-of-the-art techniques in
perceptually challenging environments, and demonstrate top-class localization
accuracy along with substantial improvements in robustness to sensor failures.
We then demonstrate real-time performance of LOCUS on various types of robotic
mobility platforms involved in the autonomous exploration of the Satsop power
plant in Elma, WA where the proposed system was a key element of the CoSTAR
team's solution that won first place in the Urban Circuit of the DARPA
Subterranean Challenge.Comment: Accepted for publication at IEEE Robotics and Automation Letters,
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