5,491 research outputs found
Robust moving horizon H∞ control of discrete time-delayed systems with interval time-varying delays
In this study, design of a delay-dependent type moving horizon state-feedback control (MHHC) is considered for a class of linear discrete-time system subject to time-varying state delays, norm-bounded uncertainties, and disturbances with bounded energies. The closed-loop robust stability and robust performance problems are considered to overcome the instability and poor disturbance rejection performance due to the existence of parametric uncertainties and time-delay appeared in the system dynamics. Utilizing a discrete-time Lyapunov-Krasovskii functional, some delay-dependent linear matrix inequality (LMI) based conditions are provided. It is shown that if one can find a feasible solution set for these LMI conditions iteratively at each step of run-time, then we can construct a control law which guarantees the closed-loop asymptotic stability, maximum disturbance rejection performance, and closed-loop dissipativity in view of the actuator limitations. Two numerical examples with simulations on a nominal and uncertain discrete-time, time-delayed systems, are presented at the end, in order to demonstrate the efficiency of the proposed method
Anomalous resonant production of the fourth family up type quarks at the LHC
Considering the present limits on the masses of fourth family quarks from the
Tevatron experiments, the fourth family quarks are expected to have mass larger
than the top quark. Due to their expected large mass they could have different
dynamics than the quarks of three families of the Standard Model. The resonant
production of the fourth family up type quark t' has been studied via anomalous
production subprocess gq_i-->t' (where q_i=u,c) at the LHC with the center of
mass energy 10 TeV and 14 TeV. The signatures of such process are discussed
within the SM decay modes. The sensitivity to anomalous coupling
\kappa/\Lambda=0.1 TeV^(-1) can be reached at \sqrt{s}=10 TeV and L_int=100
pb^(-1).Comment: 14 pages, 13 figures, 7 table
Evanescent incompressible strips as origin of the observed Hall resistance overshoot
In this work we provide a systematic explanation to the unusual non-monotonic
behavior of the Hall resistance observed at two-dimensional electron systems.
We use a semi-analytical model based on the interaction theory of the integer
quantized Hall effect to investigate the existence of the anomalous, \emph{i.e}
overshoot, Hall resistance . The observation of the overshoot resistance
at low magnetic field edge of the plateaus is elucidated by means of
overlapping evanescent incompressible strips, formed due to strong magnetic
fields and interactions. Utilizing a self-consistent numerical scheme we also
show that, if the magnetic field is decreased the decreases to its
expected value. The effects of the sample width, temperature, disorder strength
and magnetic field on the overshoot peaks are investigated in detail. Based on
our findings, we predict a controllable procedure to manipulate the maxima of
the peaks, which can be tested experimentally. Our model does not depend on
specific and intrinsic properties of the material, provided that a single
particle gap exists.Comment: A theoretical follow-up paper of arXiv:1007.258
Dating the Sea of Marmara sediments by a uniform mixing model
The sedimentation rates and Pb-210 fluxes on sediment surfaces were measured in the north, northwestern and southwestern parts of the Sea of Marmara. Each core had varying thickness of constant Pb-210 activity regions followed by a decreasing part with sediment depth. The sedimentation rates of the samples collected from the Bosporus and the Dardanelles could not be analysed due to the homogenization of activity in the strong currents of these straits. A uniform mixing model is proposed for the simultaneous analysis of sedimentation rates, Pb-210 fluxes and mixing depths from the experimental data. In this model, the parameters were obtained by minimizing the multi-dimensional parameter space using a grid search algorithm. The Pb-210 fluxes were found to be about 0.048 Bq cm(-2) year(-1) for all sampling sites. The mass sedimentation rates were 0.19 and 0.073 g cm(-2) year(-1) at the shelves of the Bosporus and the Dardanelles and 0.055 and 0.064 g cm(-2) year(-1) in the northwestern and middle northern basins, respectively, of the Sea of Marmara. Copyright (C) 1996 Elsevier Science Limite
Pulsed Beam Tests at the SANAEM RFQ Beamline
A proton beamline consisting of an inductively coupled plasma (ICP) source,
two solenoid magnets, two steerer magnets and a radio frequency quadrupole
(RFQ) is developed at the Turkish Atomic Energy Authority's (TAEA) Saraykoy
Nuclear Research and Training Center (SNRTC-SANAEM) in Ankara. In Q4 of 2016,
the RFQ was installed in the beamline. The high power tests of the RF power
supply and the RF transmission line were done successfully. The high power RF
conditioning of the RFQ was performed recently. The 13.56 MHz ICP source was
tested in two different conditions, CW and pulsed. The characterization of the
proton beam was done with ACCTs, Faraday cups and a pepper-pot emittance meter.
Beam transverse emittance was measured in between the two solenoids of the
LEBT. The measured beam is then reconstructed at the entrance of the RFQ by
using computer simulations to determine the optimum solenoid currents for
acceptance matching of the beam. This paper will introduce the pulsed beam test
results at the SANAEM RFQ beamline. In addition, the high power RF conditioning
of the RFQ will be discussed.Comment: 6 pages, 6 figures. Proceedings of the International Particle
Accelerator Conference 2017 (IPAC'17), May 14-19, 2017, TUPAB015, p. 134
A Novel Encryption Method for Dorsal Hand Vein Images on a Microcomputer
In this paper, a Lorenz-like chaotic system was developed to encrypt the dorsal hand patterns on a microcomputer. First, the dorsal hand vein images were taken from the subjects via an infrared camera. These were subjected to two different processes called contrast enhancement and segmentation of vein regions. Second, the pre- and post-processed images were encrypted with a new encryption algorithm in the microcomputer environment. For the encryption process, random numbers were generated by the chaotic system. These random numbers were subjected to NIST-800-22 test which is the most widely accepted statistical test suite. The speeded up robust feature (SURF) matching algorithm was utilized in the initial condition sensitivity analysis of the encrypted images. The results of the analysis have shown that the proposed encryption algorithm can be used in identification and verification systems. The encrypted images were analyzed with histogram, correlation, entropy, pixel change rate (NPCR), initial condition sensitivity, data loss, and noise attacks which are frequently used for security analyses in the literature. In addition, the images were analyzed after noise attacks by means of peak signal-to-noise ratio (PSNR), mean square error (MSE), and the structural similarity index (SSIM) tests. It has been shown that the dorsal hand vein images can be used in identification systems safely with the help of the proposed method on microcomputers.This work was supported by the Qatar National-LibraryScopu
SELF-REGULATION OF NOVICE MIDDLE SCHOOL MATHEMATICS TEACHERS IN THE PREPARATION PROCESS FOR TEACHING
This study analyses the self-regulation (goal setting and planning) of the novice middle school mathematics teachers during the preparation phase of teaching. The study is designed as a case study. The participants are six mathematics teachers with less than five-year teaching experience. The data were collected through interviews, observations and document analysis. In regard to the observations, the teaching of certain topics (e.g., basic elements of prisms) were observed to uncover the classroom behavior of the participants. In the semi-structured interviews carried out after the class observations, the participants were asked some questions about their goals and planning concerning the related teaching activities. The findings of the study indicate that the participants do not exhibit the goal setting and planning activities that are consistent with the conceptual learning covered in the mathematics education program. It is also found that they do not set clear goals and develop detailed planning in regard to teaching activities
Determination of trace elements in the plants of Mt. Bozdag, Izmir, Turkey
The aim of this study was to determine the current level of atmospheric heavy metal content on the Bozdag Mountain of the Aegean Region, Turkey. Twenty nine different plants were selected to study their potential as biomonitors of trace elements such as Ni, Zn, Fe, Pb, Mn and Cd (μg g-1, dry weight). The samples were collected from two different altitudes of Mt. Bozdag. The concentrations of trace elements were determined by atomic absorption spectrometry. The mean concentrations determined at 1000 m altitude ranged from 0.025 to 1.609, 0.232 to 0.731, 0.578 to 5.983, 0.287 to 0.565 and 0.176 to 2.659 (μg g-1, dry weight), for Ni, Zn, Fe, Pb and Mn, respectively. At the altitude of 1600 m, the values ranged from 0.023 to 0.939, 0.258 to 1.254, 0.839 to 5.176, 0.301 to 1.341 and 0.405 to 3.351 (μg g-1, dry weight) for Ni, Zn, Fe, Pb and Mn, respectively. No Cd was detected at either altitude. Statistical significance was determined by the independent sample t-test and comparisons were made in order to determine if there were any differences between the averages of herbaceous and woody plants.
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