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Sample records for adaptive modulation techniques

  1. Performance Evaluation of Wimax Physical Layer under Adaptive Modulation Techniques and Communication Channels

    Islam, Md Ashraful; Hasan, Md Zahid

    2009-01-01

    Wimax (Worldwide Interoperability for Microwave Access) is a promising technology which can offer high speed voice, video and data service up to the customer end. The aim of this paper is the performance evaluation of an Wimax system under different combinations of digital modulation (BPSK, QPSK, 4 QAM and 16 QAM) and different communication channels AWGN and fading channels (Rayleigh and Rician). And the Wimax system incorporates Reed Solomon (RS) encoder with Convolutional encoder with half and two third rated codes in FEC channel coding. The simulation results of estimated Bit Error Rate (BER) displays that the implementation of interleaved RS code (255, 239, 8) with two third rated Convolutional code under BPSK modulation technique is highly effective to combat in the Wimax communication system. To complete this performance analysis in Wimax based systems, a segment of audio signal is used for analysis. The transmitted audio message is found to have retrieved effectively under noisy situation.

  2. Adaptive modulations of martensites

    Kaufmann, S.; Roßler, U.K.; Heczko, Oleg; Wuttig, M.; Buschbeck, J.; Schultz, L.; Fähler, S.

    2010-01-01

    Roč. 104, č. 14 (2010), 145702/1-145702/4. ISSN 0031-9007 Institutional research plan: CEZ:AV0Z10100520 Keywords : adaptive concept of modulated martensite * martensitic Ni-Mn-Ga films * austenite * 14M martensite Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.621, year: 2010 http://link.aps.org/doi/10.1103/PhysRevLett.104.145702

  3. Attention modulates visual size adaptation.

    Kreutzer, Sylvia; Fink, G R; R. Weidner

    2015-01-01

    The current study determined in healthy subjects (n = 16) whether size adaptation occurs at early, i.e., preattentive, levels of processing or whether higher cognitive processes such as attention can modulate the illusion. To investigate this issue, bottom-up stimulation was kept constant across conditions by using a single adaptation display containing both small and large adapter stimuli. Subjects' attention was directed to either the large or small adapter stimulus by means of a luminance ...

  4. Reward Modulates Adaptations to Conflict

    Braem, Senne; Verguts, Tom; Roggeman, Chantal; Notebaert, Wim

    2012-01-01

    Both cognitive conflict (e.g. Verguts & Notebaert, 2009) and reward signals (e.g. Waszak & Pholulamdeth, 2009) have been proposed to enhance task-relevant associations. Bringing these two notions together, we predicted that reward modulates conflict-based sequential adaptations in cognitive control. This was tested combining either a single…

  5. Adaptive cancellation techniques

    1983-11-01

    An adaptive signal canceller has been evaluated for the enhancement of pulse signal reception during the transmission of a high power ECM jamming signal. The canceller design is based on the use of DRFM(Digital RF Memory) technology as part of an adaptive multiple tapped delay line. The study includes analysis of relationship of tap spacing and waveform bandwidth, survey of related documents in areas of sidelobe cancellers, transversal equalizers, and adaptive filters, and derivation of control equations and corresponding control processes. The simulation of overall processes included geometric analysis of the multibeam transmitting antenna, multiple reflection sources and the receiving antenna; waveforms, tap spacings and bandwidths; and alternate control algorithms. Conclusions are provided regarding practical system control algorithms, design characteristics and limitations.

  6. Semiconductor-laser modulation techniques

    Three simple modulation techniques for semiconductor lasers have been described. The first technique employs a single constant current source and is suitable for low frequency modulation up to 500 Khz. The second and third techniques employ two constant current sources each with current summing of subtraction and are suitable for higher frequency modulation up to several MHz. Schematic diagrams of designed, developed and tested circuits, implementing each of the above mentioned schemes, have also been presented. (author)

  7. Techniques of English Textbooks Adaptation

    张婧雯; 杨竞欧

    2014-01-01

    This essay attempts to aim English teachers to evaluate and adapt the current English textbooks.According to different levels and majors of the students,English teachers can enhance the teaching materials and their teaching skills.This paper would provide several useful techniques for teachers to make evaluations and adaptations of using teaching materials.

  8. Lunar Module 5 mated with Spacecraft Lunar Module Adapter (SLA)

    1969-01-01

    Interior view of the Kennedy Space Center's (KSC) Manned Spacecraft Operations Building showing Lunar Module 5 mated to its Spacecraft Lunar Module Adapter (SLA). LM-5 is scheduled to be flown on the Apollo 11 lunar landing mission.

  9. Improvement of Quality of Service (QoS in MISO-OFDM Systems Using Superposition Based Adaptive Modulation (SPAM and Space Frequency Block Coding (SFBC Technique

    K.Vinoth Babu

    2013-06-01

    Full Text Available 4G based wireless communication systems require high data rate with high QoS with minimal system complexity. In wireless environment, as the effect of multipath fading increases, Bit Error Rate (BER also increases. To offer high data rate, the bandwidth has to be increased which is a limited resource. The best possible solution for obtaining high data rate is to combine Multi Input Multi Output (MIMO with OFDM. To ameliorate the performance of MIMO-OFDM systems over multipath fading channels, we use the concept of SFBC which retrieves the orthogonality property of OFDM signals in frequency selective fading channels. In frequency selective fading environment, adaptive modulation gives better performance than fixed modulated systems but with increased decoding complexity. Adaptive modulation implemented with SPAM offers less decoding complexity. Adaptive modulation combined with diversity schemes still improves the reliability of the system. In this paper, SPAM based SFBC is proposed with OFDM to give better performance with less decoding complexity. From the Simulationresults we can conclude that proposed system will have better performance compared to fixed modulated systems.

  10. Downhole drilling network using burst modulation techniques

    Hall; David R. , Fox; Joe

    2007-04-03

    A downhole drilling system is disclosed in one aspect of the present invention as including a drill string and a transmission line integrated into the drill string. Multiple network nodes are installed at selected intervals along the drill string and are adapted to communicate with one another through the transmission line. In order to efficiently allocate the available bandwidth, the network nodes are configured to use any of numerous burst modulation techniques to transmit data.

  11. Adaptive Modulation and Coding for LTE Wireless Communication

    Hadi, S. S.; Tiong, T. C.

    2015-04-01

    Long Term Evolution (LTE) is the new upgrade path for carrier with both GSM/UMTS networks and CDMA2000 networks. The LTE is targeting to become the first global mobile phone standard regardless of the different LTE frequencies and bands use in other countries barrier. Adaptive Modulation and Coding (AMC) is used to increase the network capacity or downlink data rates. Various modulation types are discussed such as Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM). Spatial multiplexing techniques for 4×4 MIMO antenna configuration is studied. With channel station information feedback from the mobile receiver to the base station transmitter, adaptive modulation and coding can be applied to adapt to the mobile wireless channels condition to increase spectral efficiencies without increasing bit error rate in noisy channels. In High-Speed Downlink Packet Access (HSDPA) in Universal Mobile Telecommunications System (UMTS), AMC can be used to choose modulation types and forward error correction (FEC) coding rate.

  12. A Novel Broadband MIMO/OFDM System Using Adaptive Modulation and Adaptive Diversity

    PANYahan; KhaledBenLetaief; CAOZhigang; QIUYonghong

    2005-01-01

    OFDM (Orthogonal frequency division multiplexing) has been widely regarded as an effective modulation technique for mitigating the effects of ISI in a frequency selective fading channel and for providing reliable high-data transmission over wireless links. Adaptive modulation combined with adaptive transmit and receive diversity can achieve further increases in system's capacity and bandwidth efficiency, as well as in QoS improvement in conventional OFDM systems. In this paper, we propose a novel broadband MIMO/OFDM system using adaptive modulation and adaptive transmit and receive diversity. By applying an EVD on each sub-carrier channel matrix, joint optimal transmit and receive antenna weights as well as maximal SNR on each sub-carrier are obtained. Then, by employing adaptive modulation on each sub-carrier, the maximal SNR on each sub-carrier obtained by adaptive transmit and receive diversity is further maximized through adaptive bit assignment and power assignment on each sub-carrier under the constraint of power and overall bit rate. Simulation results show that the proposed system can achieve better performance than an adaptive antenna array based OFDM system without adaptive modulation over multipath fading channels.

  13. New Adaptive Optics Technique Demonstrated

    2007-03-01

    First ever Multi-Conjugate Adaptive Optics at the VLT Achieves First Light On the evening of 25 March 2007, the Multi-Conjugate Adaptive Optics Demonstrator (MAD) achieved First Light at the Visitor Focus of Melipal, the third Unit Telescope of the Very Large Telescope (VLT). MAD allowed the scientists to obtain images corrected for the blurring effect of atmospheric turbulence over the full 2x2 arcminute field of view. This world premiere shows the promises of a crucial technology for Extremely Large Telescopes. ESO PR Photo 19a/07 ESO PR Photo 19a/07 The MCAO Demonstrator Telescopes on the ground suffer from the blurring effect induced by atmospheric turbulence. This turbulence causes the stars to twinkle in a way which delights the poets but frustrates the astronomers, since it blurs the fine details of the images. However, with Adaptive Optics (AO) techniques, this major drawback can be overcome so that the telescope produces images that are as sharp as theoretically possible, i.e., approaching space conditions. Adaptive Optics systems work by means of a computer-controlled deformable mirror (DM) that counteracts the image distortion induced by atmospheric turbulence. It is based on real-time optical corrections computed from image data obtained by a 'wavefront sensor' (a special camera) at very high speed, many hundreds of times each second. The concept is not new. Already in 1989, the first Adaptive Optics system ever built for Astronomy (aptly named "COME-ON") was installed on the 3.6-m telescope at the ESO La Silla Observatory, as the early fruit of a highly successful continuing collaboration between ESO and French research institutes (ONERA and Observatoire de Paris). Ten years ago, ESO initiated an Adaptive Optics program to serve the needs for its frontline VLT project. Today, the Paranal Observatory is without any doubt one of the most advanced of its kind with respect to AO with no less than 7 systems currently installed (NACO, SINFONI, CRIRES and

  14. MULTICARRIER DS-CDMA WITH ADAPTIVE MODULATION AND POWER ALLOCATION

    Zhao Yahong; Zhang Zhongpei; Wu Weiling

    2003-01-01

    Adaptive modulation and power allocation is introduced into the multicarrier DS-CDMA system to improve the system performance and bandwidth efficiency. First, the systemdesign appropriate for adaptive modulation and power allocation is given, then the algorithmof adaptive modulation and power allocation is applied. Simulation results demonstrate greatperformance improvement compared with the fixed modulated one.

  15. Decoding information by following parameter modulation with parameter adaptive control

    Zhou, Changsong; Lai, C.-H.

    1999-06-01

    It has been proposed to realize secure communication using chaotic synchronization via transmission of a binary message encoded by parameter modulation in the chaotic system. This paper considers the use of parameter adaptive control techniques to extract the message, based on the assumptions that we know the equation form of the chaotic system in the transmitter but do not have access to the precise values of the parameters which are kept secret as a secure set. In the case in which a synchronizing system can be constructed using parameter adaptive control by the transmitted signal and the synchronization is robust to parameter mismatches, the parameter modulation can be revealed and the message decoded without resorting to exact parameter values in the secure set. A practical local Lyapunov function method for designing parameter adaptive control rules based on originally synchronized systems is presented.

  16. Decoding Information by Following Parameter Modulation With Parameter Adaptive Control

    Zhou, Changsong; Lai, C.-H.

    2000-01-01

    It has been proposed to realize secure communication using chaotic synchronization via transmission of binary message encoded by parameter modulation in the chaotic system. This paper considers the use of parameter adaptive control techniques to extract the message, based on the assumptions that we know the equation form of the chaotic system in the transmitter but do not have access to the precise values of the parameters which are kept secret as a secure set. In the case that a synchronizin...

  17. Adaptive techniques in electrical impedance tomography reconstruction

    We present an adaptive algorithm for solving the inverse problem in electrical impedance tomography. To strike a balance between the accuracy of the reconstructed images and the computational efficiency of the forward and inverse solvers, we propose to combine an adaptive mesh refinement technique with the adaptive Kaczmarz method. The iterative algorithm adaptively generates the optimal current patterns and a locally-refined mesh given the conductivity estimate and solves for the unknown conductivity distribution with the block Kaczmarz update step. Simulation and experimental results with numerical analysis demonstrate the accuracy and the efficiency of the proposed algorithm. (paper)

  18. Comparison of Modulation Techniques Used In WCDMA

    Ciana Barretto,

    2014-01-01

    Full Text Available Wideband Code Division Multiple Access (WCDMA was introduced to provide higher data rates in mobile communication. This technology provides the users with many multimedia rich applications such as video streams and high resolution pictures. Thus in order to enhance the performance of this technology it is necessary to determine a suitable modulation technique. Also suitable error correcting mechanisms need to be implemented to enhance these services. Analysis of these techniques is crucial to improve the performance of a system. We have considered two modulation techniques of Quadrature Amplitude Modulation (QAM and Quadrature Phase Shift Keying (QPSK used in WCDMA systems. We have studied the performance of these two modulation techniques and compared them using the parameters of eye pattern. This analysis will help us determine a suitable modulation technique for WCDMA. We have used MATLAB for the simulation of WCDMA transmitter section.

  19. An adaptive envelope spectrum technique for bearing fault detection

    In this work, an adaptive envelope spectrum (AES) technique is proposed for bearing fault detection, especially for analyzing signals with transient events. The proposed AES technique first modulates the signal using the empirical mode decomposition to formulate the representative intrinsic mode functions (IMF), and then a novel IMF reconstruction method is proposed based on a correlation analysis of the envelope spectra. The reconstructed signal is post-processed by using an adaptive filter to enhance impulsive signatures, where the filter length is optimized by the proposed sparsity analysis technique. Bearing health conditions are diagnosed by examining bearing characteristic frequency information on the envelope power spectrum. The effectiveness of the proposed fault detection technique is verified by a series of experimental tests corresponding to different bearing conditions. (paper)

  20. Adaptive Modulation for a Downlink Multicast Channel in OFDMA Systems

    Wang, Haibo; Schwefel, Hans-Peter; Toftegaard, Thomas Skjødeberg

    2007-01-01

    In this paper we focus on adaptive modulation strategies for multicast service in orthogonal frequency division multiple access systems. A reward function has been defined as the optimization target, which includes both the average user throughput and bit error rate. We also developed an adaptive...... modulation strategy, namely local best reward strategy, to maximize this reward function. The performance of different modulation strategies are compared in different SNR distribution scenarios, and the optimum strategy in each scenario is suggested....

  1. Adaptive modulation for a downlink multicast channel in OFDMA systems

    Wang, Haibo; Schwefel, Hans-Peter; Toftegaard, Thomas Skjødeberg

    2007-01-01

    In this paper we focus on adaptive modulation strategies for Multicast service in orthogonal frequency division multiple access systems. A Reward function has been defined as the optimization target, which includes both the average user throughput and bit error rate. We also developed an adaptive...... modulation strategy, namely Local Best Reward strategy, to maximize this Reward function. The performance of different modulation strategies are compared in different SNR distribution scenarios, and the optimum strategy in each scenario is suggested....

  2. Modulation and Coding Techniques in Wireless Communications

    Casares Giner, Vicente; Martínez Zaldívar, Francisco José

    2012-01-01

    This is a timely book on wireless communications, with twelve chapters covering theoretical results and material of standards. The first nine chapters, some 380 pages, are devoted to basic concepts on channel models, modulation, coding, equalization, MIMO techniques, and multiple access methods. The last three chapters extend up to 274 pages and cover the modern wireless communication standards

  3. Subset Optimization of Adaptive Coding and Modulation Schemes for Broadband Satellite Systems

    Boussemart, Vincent; Brandt, Hartmut; Berioli, Matteo

    2010-01-01

    The number of Coding and Modulation Schemes suggested for the two standards DVB-S2 and DVB-RCS (in its "advanced" version) is clearly overdimensioned; a subset of schemes can be used by reducing the overall system performance negligibly. This paper presents the investigations performed on this rain fading mitigation technique, called Adaptive Coding and Modulation (ACM), supported by the DVB-S2 standard and shows how the sets of modulation and coding schemes, considered in the forward- and in...

  4. Simulation of Digital Modulation Techniques Using MATLAB

    Neha Sharma, Yogendra Yadav

    2012-12-01

    Full Text Available In Digital modulation the message signal is in the digital form and the carrier wave is in sinusoidal form. In this technique the Amplitude, Frequency or Phase of carrier varies according to message (Baseband signal. There are various type of digital modulation technique like Amplitude Shift Keying (ASK, Phase Shift Keying (PSK, Frequency Shift Keying (FSK, Quadature Phase Shift Keying (QPSK, Differential Phase Shift Keying (DPSK and other digital demodulation technique. Simulation is the imitation of the operation of a real-world process or system over time. The act of simulating something first requires that a model be developed; this model represents the key characteristics or behaviors of the selected physical or abstract system or process. The model represents the system itself, whereas the simulation represents the operation of the system over time. Simulation is used in many contexts, such as simulation of technology for performance optimization, safety engineering, testing, training, education, and video games. So in this paper we will simulate and verify the waveform of modulating wave, carrier wave and modulated wave of Amplitude Shift Keying (ASK, Phase Shift Keying (PSK, Frequency Shift Keying FSK, Quadature Phase Shift keying (QPSK.

  5. Research on Threshold Adjustment Algorithm in Adaptive Modulation and Coding

    FAN Chen; CHEN Mei-ya; SU Li-jun; YANG Da-cheng

    2006-01-01

    Adaptive Modulation and Coding (AMC) has gained a lot of attentions in the research of High Speed Downlink Packet Access (HSDPA). The idea is to adapt the transmission to the fast changing channel conditions by the use of different Modulation and Coding Schemes (MCS). This paper presents an adaptive AMC algorithm and introduces a theoretical analysis model in order to to investigate its throughput and Frame Error Rate (FER). Subject to the given FER target, our numerical and link level simulation results both show that our algorithm outperforms other existing adaptive algorithms.

  6. The transmission of low frequency medical data using delta modulation techniques.

    Arndt, G. D.; Dawson, C. T.

    1972-01-01

    The transmission of low-frequency medical data using delta modulation techniques is described. The delta modulators are used to distribute the low-frequency data into the passband of the telephone lines. Both adaptive and linear delta modulators are considered. Optimum bit rates to minimize distortion and intersymbol interference are discussed. Vibrocardiographic waves are analyzed as a function of bit rate and delta modulator configuration to determine their reproducibility for medical evaluation.

  7. On the Performance of Adaptive Modulation in Cognitive Radio Networks

    Foukalas, F.; Karetsos, G. T.

    2013-01-01

    We study the performance of cognitive radio networks (CRNs) when incorporating adaptive modulation at the physical layer. Three types of CRNs are considered, namely opportunistic spectrum access (OSA), spectrum sharing (SS) and sensing-based SS. We obtain closed-form expressions for the average spectral efficiency achieved at the secondary network and the optimal power allocation for both continuous and discrete rate types of adaptive modulation assuming perfect channel state information. The...

  8. Adaptive Redunant Residue Number System Coded Multicarrier Modulation

    Keller, T.; Liew, T.H.; Hanzo, L.

    2000-01-01

    The novel class of nonbinary maximum minimum distance redundant residue number system (RRNS) codes is iinvoked in the context of adaptively RRNS coded, symbol-by-symbol adaptive multicarrier modulation, in order to combat the effects of frequency-selective fading inflicted by dispersive wide-band channels. The system’s performance can be adjusted in order to maintain a given target bit error rate (BER) and bit per symbol (BPS)performance. The proposed adaptive RRNS scheme outperforms the conv...

  9. Experiments on Adaptive Techniques for Host-Based Intrusion Detection

    This research explores four experiments of adaptive host-based intrusion detection (ID) techniques in an attempt to develop systems that can detect novel exploits. The technique considered to have the most potential is adaptive critic designs (ACDs) because of their utilization of reinforcement learning, which allows learning exploits that are difficult to pinpoint in sensor data. Preliminary results of ID using an ACD, an Elman recurrent neural network, and a statistical anomaly detection technique demonstrate an ability to learn to distinguish between clean and exploit data. We used the Solaris Basic Security Module (BSM) as a data source and performed considerable preprocessing on the raw data. A detection approach called generalized signature-based ID is recommended as a middle ground between signature-based ID, which has an inability to detect novel exploits, and anomaly detection, which detects too many events including events that are not exploits. The primary results of the ID experiments demonstrate the use of custom data for generalized signature-based intrusion detection and the ability of neural network-based systems to learn in this application environment

  10. Dual Adaptive Turbo Coded Modulation for Integrated Multimedia Service Transmission

    左健存; 宋文涛; 罗汉文; 徐友云

    2004-01-01

    This paper proposes a cross-layer dual adaptive coded modulation architecture using turbo codes for mobile multimedia communication, which adapts to both the varying channel characteristics and the QoS of various multimedia services simultaneously to increase the average system throughput substantially. A pragmatic channeladaptive turbo coded modulation scheme, which comes within 2.5 Db of the Shannon limit, is optimally designed,and then a QoS-adaptive scheme is superimposed to build the dual adaptive architecture. Simulation results show that the novel dual adaption reduces the gap from the fading channel capacity to 2 Db when assuming different services occur in equal probability and the service duration follows exponential distribution.

  11. Applying perceptual and adaptive learning techniques for teaching introductory histopathology

    Sally Krasne

    2013-01-01

    Full Text Available Background: Medical students are expected to master the ability to interpret histopathologic images, a difficult and time-consuming process. A major problem is the issue of transferring information learned from one example of a particular pathology to a new example. Recent advances in cognitive science have identified new approaches to address this problem. Methods: We adapted a new approach for enhancing pattern recognition of basic pathologic processes in skin histopathology images that utilizes perceptual learning techniques, allowing learners to see relevant structure in novel cases along with adaptive learning algorithms that space and sequence different categories (e.g. diagnoses that appear during a learning session based on each learner′s accuracy and response time (RT. We developed a perceptual and adaptive learning module (PALM that utilized 261 unique images of cell injury, inflammation, neoplasia, or normal histology at low and high magnification. Accuracy and RT were tracked and integrated into a "Score" that reflected students rapid recognition of the pathologies and pre- and post-tests were given to assess the effectiveness. Results: Accuracy, RT and Scores significantly improved from the pre- to post-test with Scores showing much greater improvement than accuracy alone. Delayed post-tests with previously unseen cases, given after 6-7 weeks, showed a decline in accuracy relative to the post-test for 1 st -year students, but not significantly so for 2 nd -year students. However, the delayed post-test scores maintained a significant and large improvement relative to those of the pre-test for both 1 st and 2 nd year students suggesting good retention of pattern recognition. Student evaluations were very favorable. Conclusion: A web-based learning module based on the principles of cognitive science showed an evidence for improved recognition of histopathology patterns by medical students.

  12. Module for adaptative teaching planning for a tutoring system

    Ceyca Ceyca, Jorge Omar; Pazos Rangel, Rodolfo A.; Ruiz Vanoye, Jorge Alberto

    2007-01-01

    The teaching process has been strengthened by the emergence of modern computer technologies, which have permitted developing distance education mainly through the use of the Internet. In this field tutoring systems have become one the most benefited and important tools for teaching. However, adapting tutoring systems to students’ capacity is one the issues that has just begun being explored [1, 2]. This paper describes a module for adaptive teaching planning for a tutoring system that is u...

  13. Study on rotating modulator imaging technique

    Background: Nuclear security and safety is becoming one of the most concerned topics around the world after Fukushima nuclear accident. Recent reports of IAEA show that the potential risks exist internationally and domestically. A good solution of promoting nuclear security and safety is to develop advanced nuclear radiation monitoring technologies including γ-ray imaging. Purpose: In order to improve the sensitivity of a γ-ray imaging system with little increase of system complexity and cost, rotating modulator (RM) imaging technique using non-position-sensitive detectors was first introduced in nuclear monitoring studies. Methods: Modulation pattern of RM system was deduced mathematically and its profile was calculated by a dedicated program written in Matlab. The system sensitivity was analyzed based on the profile. Detector outputs were produced by Monte Carlo simulation. The Noise-Compensating Algebraic Reconstruction (NCAR) algorithm was applied to the image reconstruct from simulated outputs. Results: A RM imaging system has a relative sensitivity of 62% compared with a coded aperture system when detector areas of the two systems are equal. On condition that the detector diameter is 3.8 cm and image distance is 80 cm, an angular resolution of 0.8° is achieved. Conclusion: Based on the simulating results, a RM system design suitable for vehicle and robotic platform is proposed. (authors)

  14. Satellite Media Broadcasting with Adaptive Coding and Modulation

    Georgios Gardikis

    2009-01-01

    Full Text Available Adaptive Coding and Modulation (ACM is a feature incorporated into the DVB-S2 satellite specification, allowing real-time adaptation of transmission parameters according to the link conditions. Although ACM was originally designed for optimizing unicast services, this article discusses the expansion of its usage to broadcasting streams as well. For this purpose, a general cross-layer adaptation approach is proposed, along with its realization into a fully functional experimental network, and test results are presented. Finally, two case studies are analysed, assessing the gain derived by ACM in a real large-scale deployment, involving HD services provision to two different geographical areas.

  15. Intrinsic gain modulation and adaptive neural coding

    Hong, Sungho; Fairhall, Adrienne

    2008-01-01

    In many cases, the computation of a neural system can be reduced to a receptive field, or a set of linear filters, and a thresholding function, or gain curve, which determines the firing probability; this is known as a linear/nonlinear model. In some forms of sensory adaptation, these linear filters and gain curve adjust very rapidly to changes in the variance of a randomly varying driving input. An apparently similar but previously unrelated issue is the observation of gain control by background noise in cortical neurons: the slope of the firing rate vs current (f-I) curve changes with the variance of background random input. Here, we show a direct correspondence between these two observations by relating variance-dependent changes in the gain of f-I curves to characteristics of the changing empirical linear/nonlinear model obtained by sampling. In the case that the underlying system is fixed, we derive relationships relating the change of the gain with respect to both mean and variance with the receptive fi...

  16. Performance analysis of joint diversity combining, adaptive modulation, and power control schemes

    Qaraqe, Khalid A.

    2011-01-01

    Adaptive modulation and diversity combining represent very important adaptive solutions for future generations of wireless communication systems. Indeed, in order to improve the performance and the efficiency of these systems, these two techniques have been recently used jointly in new schemes named joint adaptive modulation and diversity combining (JAMDC) schemes. Considering the problem of finding low hardware complexity, bandwidth-efficient, and processing-power efficient transmission schemes for a downlink scenario and capitalizing on some of these recently proposed JAMDC schemes, we propose and analyze in this paper three joint adaptive modulation, diversity combining, and power control (JAMDCPC) schemes where a constant-power variable-rate adaptive modulation technique is used with an adaptive diversity combining scheme and a common power control process. More specifically, the modulation constellation size, the number of combined diversity paths, and the needed power level are jointly determined to achieve the highest spectral efficiency with the lowest possible processing power consumption quantified in terms of the average number of combined paths, given the fading channel conditions and the required bit error rate (BER) performance. In this paper, the performance of these three JAMDCPC schemes is analyzed in terms of their spectral efficiency, processing power consumption, and error-rate performance. Selected numerical examples show that these schemes considerably increase the spectral efficiency of the existing JAMDC schemes with a slight increase in the average number of combined paths for the low signal-to-noise ratio range while maintaining compliance with the BER performance and a low radiated power which yields to a substantial decrease in interference to co-existing users and systems. © 2011 IEEE.

  17. Amplitude modulation reduces loudness adaptation to high-frequency tones

    Wynne, DP; George, SE; Zeng, FG

    2015-01-01

    © 2015 Acoustical Society of America. Long-term loudness perception of a sound has been presumed to depend on the spatial distribution of activated auditory nerve fibers as well as their temporal firing pattern. The relative contributions of those two factors were investigated by measuring loudness adaptation to sinusoidally amplitude-modulated 12-kHz tones. The tones had a total duration of 180s and were either unmodulated or 100%-modulated at one of three frequencies (4, 20, or 100Hz), and ...

  18. Adaptive Response Surface Techniques in Reliability Estimation

    Enevoldsen, I.; Faber, M. H.; Sørensen, John Dalsgaard

    1993-01-01

    Problems in connection with estimation of the reliability of a component modelled by a limit state function including noise or first order discontinuitics are considered. A gradient free adaptive response surface algorithm is developed. The algorithm applies second order polynomial surfaces...... determined from central composite designs. In a two phase algorithm the second order surface is adjusted to the domain of the most likely failure point and both FORM and SORM estimates are obtained. The algorithm is implemented as a safeguard algorithm so non-converged solutions are avoided. Furthermore, a...

  19. Joint adaptive modulation and diversity combining with feedback error compensation

    Choi, Seyeong

    2009-11-01

    This letter investigates the effect of feedback error on the performance of the joint adaptive modulation and diversity combining (AMDC) scheme which was previously studied with an assumption of error-free feedback channels. We also propose to utilize adaptive diversity to compensate for the performance degradation due to feedback error. We accurately quantify the performance of the joint AMDC scheme in the presence of feedback error, in terms of the average number of combined paths, the average spectral efficiency, and the average bit error rate. Selected numerical examples are presented and discussed to illustrate the effectiveness of the proposed feedback error compensation strategy with adaptive combining. It is observed that the proposed compensation strategy can offer considerable error performance improvement with little loss in processing power and spectral efficiency in comparison with the no compensation case. Copyright © 2009 IEEE.

  20. A novel online adaptive time delay identification technique

    Bayrak, Alper; Tatlicioglu, Enver

    2016-05-01

    Time delay is a phenomenon which is common in signal processing, communication, control applications, etc. The special feature of time delay that makes it attractive is that it is a commonly faced problem in many systems. A literature search on time-delay identification highlights the fact that most studies focused on numerical solutions. In this study, a novel online adaptive time-delay identification technique is proposed. This technique is based on an adaptive update law through a minimum-maximum strategy which is firstly applied to time-delay identification. In the design of the adaptive identification law, Lyapunov-based stability analysis techniques are utilised. Several numerical simulations were conducted with Matlab/Simulink to evaluate the performance of the proposed technique. It is numerically demonstrated that the proposed technique works efficiently in identifying both constant and disturbed time delays, and is also robust to measurement noise.

  1. Comparative Study of Different Guard Time Intervals to Improve the BER Performance of Wimax Systems to Minimize the Effects of ISI and ICI under Adaptive Modulation Techniques over SUI1 and AWGN Communication Channels

    Hasan, Md Zahid; Islam, Md Ashraful; Hossain, Riaz

    2009-01-01

    The WIMAX technology based on air interface standard 802.16 wireless MAN is configured in the same way as a traditional cellular network with base stations using point to multipoint architecture to drive a service over a radius up to several kilometers. The range and the Non Line of Sight (NLOS) ability of WIMAX make the system very attractive for users, but there will be slightly higher BER at low SNR. The aim of this paper is the comparative study of different guard time intervals effect for improving BER at different SNR under digital modulation (QPSK, 16QAM and 64QAM) techniques and different communication channels AWGN and fading channels Stanford University Interim (SUI 1) of an WIMAX system. The comparison between these effects with Reed-Solomon (RS) encoder with Convolutional encoder (half) rated codes in FEC channel coding will be investigated. The simulation results of estimated Bit Error Rate (BER) displays that the implementation of interleaved RS code (255,239,8) with (half) rated Convolutional c...

  2. Power adaptation for joint switched diversity and adaptive modulation schemes in spectrum sharing systems

    Bouida, Zied

    2012-09-01

    Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using transmit power adaptation, switched transmit diversity, and adaptive modulation in order to improve the performance of existing switching efficient schemes (SES) and bandwidth efficient schemes (BES). Taking advantage of the channel reciprocity principle, we assume that the channel state information (CSI) of the interference link is available to the secondary transmitter. This information is then used by the secondary transmitter to adapt its transmit power, modulation constellation size, and used transmit branch. The goal of this joint adaptation is to minimize the average number of switched branches and the average system delay given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. We analyze the proposed scheme in terms of the average number of branch switching, average delay, and we provide a closed-form expression of the average bit error rate (BER). We demonstrate through numerical examples that the proposed scheme provides a compromise between the SES and the BES schemes. © 2012 IEEE.

  3. Radar Range Sidelobe Reduction Using Adaptive Pulse Compression Technique

    Li, Lihua; Coon, Michael; McLinden, Matthew

    2013-01-01

    Pulse compression has been widely used in radars so that low-power, long RF pulses can be transmitted, rather than a highpower short pulse. Pulse compression radars offer a number of advantages over high-power short pulsed radars, such as no need of high-power RF circuitry, no need of high-voltage electronics, compact size and light weight, better range resolution, and better reliability. However, range sidelobe associated with pulse compression has prevented the use of this technique on spaceborne radars since surface returns detected by range sidelobes may mask the returns from a nearby weak cloud or precipitation particles. Research on adaptive pulse compression was carried out utilizing a field-programmable gate array (FPGA) waveform generation board and a radar transceiver simulator. The results have shown significant improvements in pulse compression sidelobe performance. Microwave and millimeter-wave radars present many technological challenges for Earth and planetary science applications. The traditional tube-based radars use high-voltage power supply/modulators and high-power RF transmitters; therefore, these radars usually have large size, heavy weight, and reliability issues for space and airborne platforms. Pulse compression technology has provided a path toward meeting many of these radar challenges. Recent advances in digital waveform generation, digital receivers, and solid-state power amplifiers have opened a new era for applying pulse compression to the development of compact and high-performance airborne and spaceborne remote sensing radars. The primary objective of this innovative effort is to develop and test a new pulse compression technique to achieve ultrarange sidelobes so that this technique can be applied to spaceborne, airborne, and ground-based remote sensing radars to meet future science requirements. By using digital waveform generation, digital receiver, and solid-state power amplifier technologies, this improved pulse compression

  4. Study of adaptive modulation and LDPC coding in multicarrier systems

    2008-01-01

    An adaptive modulation (AM) algorithm is proposed and the application of the adapting algorithm together with low-density parity-check (LDPC) codes in multicarrier systems is investigated.The AM algorithm is based on minimizing the average bit error rate (BER) of systems,the combination of AM algorithm and LDPC codes with different code rates (half and three-fourths) are studied.The proposed AM algorithm with that of Fischer et al is compared.Simulation results show that the performance of the proposed AM algorithm is better than that of the Fischer's algorithm.The results also show that application of the proposed AM algorithm together with LDPC codes can greatly improve the performance of multicarrier systems.Results also show that the performance of the proposed algorithm is degraded with an increase in code rate when code length is the same.

  5. PERFORMANCES OF ADAPTIVE MODULATION AND CODING IN SATELLITE MOBILE CHANNEL

    Yu Fangyuan; Yang Mingchuan; Guo Qing

    2011-01-01

    Given that satellite mobile channel is a time-varying channel,Adaptive Modulation and Coding (AMC) was proposed to provide robust and spectrally efficient transmission over satellite mobile channel.Three different kinds of channel environment were considered in this paper:the urban area,the rural area,and the open space.Four combinations of modulation and coding were designed to meet reliable communication on time-varying channel,and spectral efficiency and system throughput of these three kinds of channel environment were simulated.Based on the simulation results,this paper analysed the results and compared the performances of AMC with non-AMC system in these three kinds of channel environment.At last,we come to the conclusions:a system with AMC can achieve higher spectral efficiency and better system throughput; and the spectral efficiency and system throughput of AMC system will be higher on better satellite mobile channel.

  6. Prediction-based Adaptation (PRADA) Algorithm for Modulation and Coding

    Lin, Shou-Pon; Lin, Wei-Ting; Yeh, Ping-Cheng; Su, Hsuan-Jung

    2010-01-01

    In this paper, we propose a novel adaptive modulation and coding (AMC) algorithm dedicated to reduce the feedback frequency of the channel state information (CSI). There have been already plenty of works on AMC so as to exploit the bandwidth more efficiently with the CSI feedback to the transmitter. However, in some occasions, frequent CSI feedback is not favorable in these systems. This work considers finite-state Markov chain (FSMC) based channel prediction to alleviate the feedback while maximizing the overall throughput. We derive the close-form of the frame error rate (FER) based on channel prediction using limited CSI feedback. In addition, instead of switching settings according to the CSI, we also provide means to combine both CSI and FER as the switching parameter. Numerical results illustrate that the average throughput of the proposed algorithm has significant performance improvement over fixed modulation and coding while the CSI feedback being largely reduced.

  7. POPULATION MEAN ESTIMATE FOR ADAPTIVE MODULATION UNDER LARGE PHASE ERROR IN SINGLE BEAMFORMING SENSOR ARRAY

    G. Vaikundam

    2015-04-01

    Full Text Available Beamforming is a signal processing technique to focus the transmitted energy so that maximum energy is radiated in the intended destination and communication range is enhanced. Data rate improvement in Transmit beamforming can be achieved with adaptive modulation. Though modulation adaptation is possible under zero-mean phase error, it is difficult to adapt it under non-zero mean Gaussian distributed phase error conditions. Phase errors occur due to channel estimation inaccuracies, delay in estimation, sensor drift, quantized feedback etc resulting in increased outage probability and Bit error rate. Preprocessing of beamforming weights adjusted by Sample Mean Estimate (SME solves the problem of adaptive modulation. However, under large phase error variation, the SME method fails. Hence, in this paper, Population Mean Estimate (PME approach is proposed to resolve these drawbacks for a Rayleigh flat fading channel with White Gaussian Noise. To correct the population mean error if any, Least Mean Square correction algorithm is proposed and is tested up to 80% error in PME and the corrected error fall within 10% error. Simulation results for a distributed beamforming sensor array indicate that the proposed method performs better than the SME based existing methods under worst-case phase error distribution.

  8. SOAR Adaptive Module (SAM): seeing improvement with a UV laser

    Tokovinin, Andrei; Tighe, Roberto; Schurter, Patricio; Martinez, Manuel; Thomas, Sandrine; van der Bliek, Nicole

    2016-01-01

    The adaptive module of the 4.1-m SOAR telescope, SAM, corrects ground-layer turbulence using a UV laser guide star. It has been commissioned in 2013 and it is in regular science operation since 2014. SAM works with the CCD imager covering a 3' field or with the speckle camera. It operates routinely and stably, delivering resolution in the I band equal to the free-atmosphere seeing. This paper describes the SAM system as a whole, providing essential reference for its users and technical information of interest to instrumentalists. Operation of the instrument, its performance, and science projects done with SAM so far are reviewed.

  9. Thermally tuneable optical modulator adapted for differential signaling

    Zortman, William A.

    2016-01-12

    An apparatus for optical modulation is provided. The apparatus includes a modulator structure and a heater structure. The modulator structure comprises a ring or disk optical resonator having a closed curvilinear periphery and a pair of oppositely doped semiconductor regions within and/or adjacent to the optical resonator and conformed to modify the optical length of the optical resonator upon application of a bias voltage. The heater structure comprises a relatively resistive annulus of semiconductor material enclosed between an inner disk and an outer annulus of relatively conductive semiconductor material. The inner disk and the outer annulus are adapted as contact regions for a heater activation current. The heater structure is situated within the periphery of the optical resonator such that in operation, at least a portion of the resonator is heated by radial conductive heat flow from the heater structure. The apparatus further includes a substantially annular isolation region of dielectric or relatively resistive semiconductor material interposed between the heater structure and the modulator structure. The isolation region is effective to electrically isolate the bias voltage from the heater activation current.

  10. ARTIFICIAL INTELLIGENCE PLANNING TECHNIQUES FOR ADAPTIVE VIRTUAL COURSE CONSTRUCTION

    NÉSTOR DARÍO DUQUE; DEMETRIO ARTURO OVALLE

    2011-01-01

    This paper aims at presenting a planning model for adapting the behavior of virtual courses based on artificial intelligence techniques, in particular using not only a multi-agent system approach, but also artificial intelligence planning methods. The design and implementation of the system by means of a pedagogical multi-agent approach and the definition of a framework to specify the adaptation strategy allow us to incorporate several pedagogical and technological approaches that are in acco...

  11. Beaconless adaptive-optics technique for HEL beam control

    Khizhnyak, Anatoliy; Markov, Vladimir

    2016-05-01

    Effective performance of forthcoming laser systems capable of power delivery on a distant target requires an adaptive optics system to correct atmospheric perturbations on the laser beam. The turbulence-induced effects are responsible for beam wobbling, wandering, and intensity scintillation, resulting in degradation of the beam quality and power density on the target. Adaptive optics methods are used to compensate for these negative effects. In its turn, operation of the AOS system requires a reference wave that can be generated by the beacon on the target. This report discusses a beaconless approach for wavefront correction with its performance based on the detection of the target-scattered light. Postprocessing of the beacon-generated light field enables retrieval and detailed characterization of the turbulence-perturbed wavefront -data that is essential to control the adaptive optics module of a high-power laser system.

  12. OFFLINE HANDWRITTEN SIGNATURE IDENTIFICATION USING ADAPTIVE WINDOW POSITIONING TECHNIQUES

    Ghazali Sulong

    2014-10-01

    Full Text Available The paper presents to address this challenge, we have proposed the use of Adaptive Window Positioning technique which focuses on not just the meaning of the handwritten signature but also on the individuality of the writer. This innovative technique divides the handwritten signature into 13 small windows of size nxn (13x13. This size should be large enough to contain ample information about the style of the author and small enough to ensure a good identification performance. The process was tested with a GPDS datasetcontaining 4870 signature samples from 90 different writers by comparing the robust features of the test signature with that of the user’s signature using an appropriate classifier. Experimental results reveal that adaptive window positioning technique proved to be the efficient and reliable method for accurate signature feature extraction for the identification of offline handwritten signatures .The contribution of this technique can be used to detect signatures signed under emotional duress.

  13. Adapted Cuing Technique for Use in Treatment of Dyspraxia.

    Klick, Susan L.

    1985-01-01

    The Adapted Cuing Technique (ACT) was created to accompany oral stimulus presentation in treatment of dyspraxia. ACT is consistent with current treatment theory, emphasizing patterns of articulatory movement, manner of production, and multimodality facilitation. A case study describes the use of ACT in the treatment of a five-year-old child.…

  14. Joint switched transmit diversity and adaptive modulation in spectrum sharing systems

    Qaraqe, Khalid A.

    2011-01-01

    Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using switched transmit diversity and adaptive modulation in order to minimize the average number of switched branches at the secondary transmitter while increasing the capacity of the secondary link. The proposed switching efficient scheme (SES) uses the scan and wait (SWC) combining technique where a transmission occurs only when a branch with an acceptable performance is found, otherwise data is buffered. In our scheme, the modulation constellation size and the used transmit branch are determined to achieve the highest spectral efficiency with a minimum processing power, given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. Selected numerical examples show that the SES scheme minimizes the average number of switched branches for the average and the high secondary signal-to-noise ratio range. This improvement comes at the expense of a small delay introduced by the SWC technique. For reference, we also compare the performance of the SES scheme to the selection diversity scheme (SDS) where the best branch verifying the modulation mode and the interference constraint is always selected. © 2011 ICST.

  15. Feedback Stabilization over Wireless Network Using Adaptive Coded Modulation

    Li Yang; Xin-Ping Guan; Cheng-Nian Long; Xiao-Yuan Luo

    2008-01-01

    In this paper, we apply adaptive coded modulation (ACM) schemes to a wireless networked control system (WNCS)to improve the energy efficiency and increase the data rate over a fading channel. To capture the characteristics of varying rate,interference, and routing in wireless transmission channels, the concepts of equivalent delay (ED) and networked condition index (NCI)are introduced. Also, the analytic lower and upper bounds of EDs are obtained. Furthermore, we model the WNCS as a multicontroller switched system (MSS) under consideration of EDs and loss index in the wireless transmission. Sufficient stability condition of the closed-loop WNCS and corresponding dynamic state feedback controllers are derived in terms of linear matrix inequality (LMI).Numerical results show the validity and advantage of our proposed control strategies.

  16. Soft-switching techniques for pulse-width-modulated converters

    Hua, Guichao

    1994-01-01

    The concept of soft-switching pulse-width-modulated (PWM) technique was proposed aimed at combining the advantages of both the conventional PWM technique and the resonant technique. This work presents four new families of soft-switching PWM converters: the zero-voltage-switched (ZVS) PWM converters, the zero-current-switched (ZCS) PWM converters, the zerovoltage- transition (ZVT) PWM converters, and the zero-current-transition (ZCT) PWM converters. The family of ZVS- and ...

  17. Performance analysis of adaptive modulation for cognitive radios with opportunistic access

    Chen, Yunfei

    2011-06-01

    The performance of adaptive modulation for cognitive radio with opportunistic access is analyzed by considering the effects of spectrum sensing and primary user traffic for Nakagami-m fading channels. Both the adaptive continuous rate scheme and the adaptive discrete rate scheme are considered. Numerical results show that spectrum sensing and primary user traffic cause considerable degradation to the bit error rate performance of adaptive modulation in a cognitive radio system with opportunistic access to the licensed channel. They also show that primary user traffic does not affect the link spectral efficiency performance of adaptive modulation, while the spectrum sensing degrades the link spectral efficiency performance. © 2011 IEEE.

  18. Federal and State Employment Laws. Module Number 11. Work Experience Program Modules. Coordination Techniques Series.

    Kidney, John

    This self-instructional module, the eleventh in a series of 16 on techniques for coordinating work experience programs, deals with federal and state employment laws. Addressed in the module are federal and state employment laws pertaining to minimum wage for student learners, minimum wage for full-time students, unemployment insurance, child labor…

  19. Use of genetically modified bacteria to modulate adaptive immunity.

    Bueno, Susan M; González, Pablo A; Kalergis, Alexis M

    2009-06-01

    Infectious diseases caused by virulent bacteria are a significant cause of morbidity and mortality worldwide, especially in developing countries. However, attenuated strains derived from pathogenic bacteria, such as Salmonella, are highly immunogenic and can be used as vaccines to promote immunity against parental pathogenic bacteria strains. Further, they can be genetically manipulated to either express foreign antigens or deliver exogenous DNA, in order to induce immunity against other pathogens or antigens. Contrarily, specific structural modifications in attenuated Salmonella have allowed the generation of strains that can be well tolerated by the immune system and reduce inflammatory responses. It is thought that those strains could be considered as vectors to promote specific immune tolerance for certain auto-antigens or allergens and reduce unwanted or self-reactive immune responses. In addition, some structural features of Salmonella can contribute to defining the nature and type of polarization of the adaptive immune response induced after immunization, which can be considered as a tool to modulate antigen-specific immunity. In this article we discuss recent advances in the understanding of immune system modulation by molecular components of bacteria and their exploitation for the rational induction of pathogen immunity or antigen-specific tolerance. PMID:19519362

  20. Functional modules of sigma factor regulons guarantee adaptability and evolvability

    Binder, Sebastian C.; Eckweiler, Denitsa; Schulz, Sebastian; Bielecka, Agata; Nicolai, Tanja; Franke, Raimo; Häussler, Susanne; Meyer-Hermann, Michael

    2016-02-01

    The focus of modern molecular biology turns from assigning functions to individual genes towards understanding the expression and regulation of complex sets of molecules. Here, we provide evidence that alternative sigma factor regulons in the pathogen Pseudomonas aeruginosa largely represent insulated functional modules which provide a critical level of biological organization involved in general adaptation and survival processes. Analysis of the operational state of the sigma factor network revealed that transcription factors functionally couple the sigma factor regulons and significantly modulate the transcription levels in the face of challenging environments. The threshold quality of newly evolved transcription factors was reached faster and more robustly in in silico testing when the structural organization of sigma factor networks was taken into account. These results indicate that the modular structures of alternative sigma factor regulons provide P. aeruginosa with a robust framework to function adequately in its environment and at the same time facilitate evolutionary change. Our data support the view that widespread modularity guarantees robustness of biological networks and is a key driver of evolvability.

  1. Dosimetrically Triggered Adaptive Intensity Modulated Radiation Therapy for Cervical Cancer

    Purpose: The widespread use of intensity modulated radiation therapy (IMRT) for cervical cancer has been limited by internal target and normal tissue motion. Such motion increases the risk of underdosing the target, especially as planning margins are reduced in an effort to reduce toxicity. This study explored 2 adaptive strategies to mitigate this risk and proposes a new, automated method that minimizes replanning workload. Methods and Materials: Thirty patients with cervical cancer participated in a prospective clinical study and underwent pretreatment and weekly magnetic resonance (MR) scans over a 5-week course of daily external beam radiation therapy. Target volumes and organs at risk (OARs) were contoured on each of the scans. Deformable image registration was used to model the accumulated dose (the real dose delivered to the target and OARs) for 2 adaptive replanning scenarios that assumed a very small PTV margin of only 3 mm to account for setup and internal interfractional motion: (1) a preprogrammed, anatomy-driven midtreatment replan (A-IMRT); and (2) a dosimetry-triggered replan driven by target dose accumulation over time (D-IMRT). Results: Across all 30 patients, clinically relevant target dose thresholds failed for 8 patients (27%) if 3-mm margins were used without replanning. A-IMRT failed in only 3 patients and also yielded an additional small reduction in OAR doses at the cost of 30 replans. D-IMRT assured adequate target coverage in all patients, with only 23 replans in 16 patients. Conclusions: A novel, dosimetry-triggered adaptive IMRT strategy for patients with cervical cancer can minimize the risk of target underdosing in the setting of very small margins and substantial interfractional motion while minimizing programmatic workload and cost

  2. Dosimetrically Triggered Adaptive Intensity Modulated Radiation Therapy for Cervical Cancer

    Lim, Karen [Department of Radiation Oncology, Liverpool Hospital, Sydney (Australia); Stewart, James [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario (Canada); Kelly, Valerie [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Xie, Jason [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Brock, Kristy K. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Moseley, Joanne [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Cho, Young-Bin; Fyles, Anthony [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Lundin, Anna; Rehbinder, Henrik; Löf, Johan [RaySearch Laboratories AB, Stockholm (Sweden); Jaffray, David A. [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario (Canada); Techna Institute for the Advancement of Technology for Health, Toronto, Ontario (Canada); Milosevic, Michael, E-mail: mike.milosevic@rmp.uhn.ca [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada)

    2014-09-01

    Purpose: The widespread use of intensity modulated radiation therapy (IMRT) for cervical cancer has been limited by internal target and normal tissue motion. Such motion increases the risk of underdosing the target, especially as planning margins are reduced in an effort to reduce toxicity. This study explored 2 adaptive strategies to mitigate this risk and proposes a new, automated method that minimizes replanning workload. Methods and Materials: Thirty patients with cervical cancer participated in a prospective clinical study and underwent pretreatment and weekly magnetic resonance (MR) scans over a 5-week course of daily external beam radiation therapy. Target volumes and organs at risk (OARs) were contoured on each of the scans. Deformable image registration was used to model the accumulated dose (the real dose delivered to the target and OARs) for 2 adaptive replanning scenarios that assumed a very small PTV margin of only 3 mm to account for setup and internal interfractional motion: (1) a preprogrammed, anatomy-driven midtreatment replan (A-IMRT); and (2) a dosimetry-triggered replan driven by target dose accumulation over time (D-IMRT). Results: Across all 30 patients, clinically relevant target dose thresholds failed for 8 patients (27%) if 3-mm margins were used without replanning. A-IMRT failed in only 3 patients and also yielded an additional small reduction in OAR doses at the cost of 30 replans. D-IMRT assured adequate target coverage in all patients, with only 23 replans in 16 patients. Conclusions: A novel, dosimetry-triggered adaptive IMRT strategy for patients with cervical cancer can minimize the risk of target underdosing in the setting of very small margins and substantial interfractional motion while minimizing programmatic workload and cost.

  3. Strategies in edge plasma simulation using adaptive dynamic nodalization techniques

    A wide span of steady-state and transient edge plasma processes simulation problems require accurate discretization techniques and can then be treated with Finite Element (FE) and Finite Volume (FV) methods. The software used here to meet these meshing requirements is a 2D finite element grid generator. It allows to produce adaptive unstructured grids taking into consideration the flux surface characteristics. To comply with the common mesh handling features of FE/FV packages, some options have been added to the basic generation tool. These enhancements include quadrilateral meshes without non-regular transition elements obtained by substituting them by transition constructions consisting of regular quadrilateral elements. Furthermore triangular grids can be created with one edge parallel to the magnetic field and modified by the basic adaptation/realignment techniques. Enhanced code operation properties and processing capabilities are expected. (author)

  4. An Adaptive Hybrid Multiprocessor technique for bioinformatics sequence alignment

    Bonny, Talal

    2012-07-28

    Sequence alignment algorithms such as the Smith-Waterman algorithm are among the most important applications in the development of bioinformatics. Sequence alignment algorithms must process large amounts of data which may take a long time. Here, we introduce our Adaptive Hybrid Multiprocessor technique to accelerate the implementation of the Smith-Waterman algorithm. Our technique utilizes both the graphics processing unit (GPU) and the central processing unit (CPU). It adapts to the implementation according to the number of CPUs given as input by efficiently distributing the workload between the processing units. Using existing resources (GPU and CPU) in an efficient way is a novel approach. The peak performance achieved for the platforms GPU + CPU, GPU + 2CPUs, and GPU + 3CPUs is 10.4 GCUPS, 13.7 GCUPS, and 18.6 GCUPS, respectively (with the query length of 511 amino acid). © 2010 IEEE.

  5. Adaptive spectral identification techniques in presence of undetected non linearities

    Cella, G; Guidi, G M

    2002-01-01

    The standard procedure for detection of gravitational wave coalescing binaries signals is based on Wiener filtering with an appropriate bank of template filters. This is the optimal procedure in the hypothesis of addictive Gaussian and stationary noise. We study the possibility of improving the detection efficiency with a class of adaptive spectral identification techniques, analyzing their effect in presence of non stationarities and undetected non linearities in the noise

  6. Load Cell Response Correction Using Analog Adaptive Techniques

    Jafaripanah, Mehdi; Al-Hashimi, Bashir; White, Neil M.

    2003-01-01

    Load cell response correction can be used to speed up the process of measurement. This paper investigates the application of analog adaptive techniques in load cell response correction. The load cell is a sensor with an oscillatory output in which the measurand contributes to response parameters. Thus, a compensation filter needs to track variation in measurand whereas a simple, fixed filter is only valid at one load value. To facilitate this investigation, computer models for the load cell a...

  7. New Adaptive Method for IQ Imbalance Compensation of Quadrature Modulators in Predistortion Systems

    Hassan Zareian

    2009-01-01

    Full Text Available Imperfections in quadrature modulators (QMs, such as inphase and quadrature (IQ imbalance, can severely impact the performance of power amplifier (PA linearization systems, in particular in adaptive digital predistorters (PDs. In this paper, we first analyze the effect of IQ imbalance on the performance of a memory orthogonal polynomials predistorter (MOP PD, and then we propose a new adaptive algorithm to estimate and compensate the unknown IQ imbalance in QM. Unlike previous compensation techniques, the proposed method was capable of online IQ imbalance compensation with faster convergence, and no special calibration or training signals were needed. The effectiveness of the proposed IQ imbalance compensator was validated by simulations. The results clearly show the performance of the MOP PD to be enhanced significantly by adding the proposed IQ imbalance compensator.

  8. New Adaptive Method for IQ Imbalance Compensation of Quadrature Modulators in Predistortion Systems

    Zareian, Hassan; Vakili, Vahid Tabataba

    2009-12-01

    Imperfections in quadrature modulators (QMs), such as inphase and quadrature (IQ) imbalance, can severely impact the performance of power amplifier (PA) linearization systems, in particular in adaptive digital predistorters (PDs). In this paper, we first analyze the effect of IQ imbalance on the performance of a memory orthogonal polynomials predistorter (MOP PD), and then we propose a new adaptive algorithm to estimate and compensate the unknown IQ imbalance in QM. Unlike previous compensation techniques, the proposed method was capable of online IQ imbalance compensation with faster convergence, and no special calibration or training signals were needed. The effectiveness of the proposed IQ imbalance compensator was validated by simulations. The results clearly show the performance of the MOP PD to be enhanced significantly by adding the proposed IQ imbalance compensator.

  9. Feasibility of an online adaptive replanning method for cranial frameless intensity-modulated radiosurgery

    Calvo, Juan Francisco, E-mail: jfcdrr@gmail.com [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain); San José, Sol [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain); Garrido, LLuís [Institut de Ciències del Cosmos i Departament ECM, Universitat de Barcelona, Barcelona (Spain); Puertas, Enrique; Moragues, Sandra; Pozo, Miquel [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain); Casals, Joan, E-mail: jfcdrr@yahoo.es [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain)

    2013-10-01

    To introduce an approach for online adaptive replanning (i.e., dose-guided radiosurgery) in frameless stereotactic radiosurgery, when a 6-dimensional (6D) robotic couch is not available in the linear accelerator (linac). Cranial radiosurgical treatments are planned in our department using intensity-modulated technique. Patients are immobilized using thermoplastic mask. A cone-beam computed tomography (CBCT) scan is acquired after the initial laser-based patient setup (CBCT{sub setup}). The online adaptive replanning procedure we propose consists of a 6D registration-based mapping of the reference plan onto actual CBCT{sub setup}, followed by a reoptimization of the beam fluences (“6D plan”) to achieve similar dosage as originally was intended, while the patient is lying in the linac couch and the original beam arrangement is kept. The goodness of the online adaptive method proposed was retrospectively analyzed for 16 patients with 35 targets treated with CBCT-based frameless intensity modulated technique. Simulation of reference plan onto actual CBCT{sub setup}, according to the 4 degrees of freedom, supported by linac couch was also generated for each case (4D plan). Target coverage (D99%) and conformity index values of 6D and 4D plans were compared with the corresponding values of the reference plans. Although the 4D-based approach does not always assure the target coverage (D99% between 72% and 103%), the proposed online adaptive method gave a perfect coverage in all cases analyzed as well as a similar conformity index value as was planned. Dose-guided radiosurgery approach is effective to assure the dose coverage and conformity of an intracranial target volume, avoiding resetting the patient inside the mask in a “trial and error” way so as to remove the pitch and roll errors when a robotic table is not available.

  10. Adaptive Modulator Design (S/W for SDR

    Gaurav Thakur

    2013-07-01

    Full Text Available With the exponential growth in the ways and means by which people need to communicate – data, voice, video, broadcast message, command and control communications etc. modifying radio devices easily and cost-effectively has become critical. The future information age is equipped with rich and affordable telecommunication services. So in future people will need flexibility while using the wireless equipments. Consider a radio which autonomously detects and exploits empty spectrum to increase your file transfer rate. What if this same radio could remember the locations where your calls tend to drop and arrange for your call to be serviced by a different carrier for those locations. These are some of the ideas motivating the development of cognitive radio (CR. In effect, a cognitive radio is a software radio whose control processes leverage situational knowledge and intelligent processing to work towards achieving some goal related to the needs of the user, application, and/or network. Wireless communications systems and standards have been developed around the world without any global plan. Recently hardware technology evolved significantly. Some of the key milestones in this progress are transition from analog hardware to digital hardware and then introduction of sophisticated processors. This is followed by the development of Software Defined Radio (SDR structures and virtual hardware that are still in development process currently. Software Defined Radio (SDR system is a useful and adaptable future-proof solution to cover both existing and emerging standards, it provides elements with re-configurability, intelligence and software programmable hardware. Moreover, it has capability of providing global seamless connectivity and solves the interoperability issue. The operating carrier frequency range for various modulation scheme is depicted in the paper. The effects of carrier noise on the modulated signal is also depicted

  11. Research on Satellite Communication Channel Estimation and Adaptive Modulation Decision Technology

    Zhendong Yin

    2013-01-01

    Full Text Available Satellite communication has become a modern indispensable means of communication. In order to reduce the BER in a maximum limit, the transmitting terminal of adaptive satellite communication technology can automatic select working frequency, data transmission rate and modulation mode. In this study, a simple and practical design of system based on the Signal-to-noise Ratio (SNR estimation scheme with adaptive modulation for satellite communication is presented. This system applies Maximum-likelihood (ML algorithm to estimate SNR. Simulation deduces the modulation mode switching threshold. In addition, the adaptive modulation switching threshold is the trade off between spectral efficiency and Bit Error Rate (BER. Furthermore, the modulation mode decision strategy should be considered to achieve the highest spectral efficiency and to maintain constant average BER. The design of an integrated SNR estimation and adaptive modulation mode decision system is highly challenging. Numerical results show that the design fulfills superior performance.

  12. A novel adaptive classification scheme for digital modulations in satellite communication

    Wu Dan; Gu Xuemai; Guo Qing

    2007-01-01

    To make the modulation classification system more suitable for signals in a wide range of signal to noise ratios (SNRs) , a novel adaptive modulation classification scheme is presented in this paper. Different from traditional schemes, the proposed scheme employs a new SNR estimation algorithm for small samples before modulation classification, which makes the modulation classifier work adaptively according to estimated SNRs. Furthermore, it uses three efficient features and support vector machines (SVM) in modulation classification. Computer simulation shows that the scheme can adaptively classify ten digital modulation types (i.e. 2ASK, 4ASK, 2FSK, 4FSK, 2PSK, 4PSK, 16QAM, TFM, π/4QPSK and OQPSK) at SNRS ranging from OdB to 25 dB and success rates are over 95% when SNR is not lower than 3dB. Accuracy, efficiency and simplicity of the proposed scheme are obviously improved, which make it more adaptive to engineering applications.

  13. An adaptive technique for a redundant-sensor navigation system.

    Chien, T.-T.

    1972-01-01

    An on-line adaptive technique is developed to provide a self-contained redundant-sensor navigation system with a capability to utilize its full potentiality in reliability and performance. This adaptive system is structured as a multistage stochastic process of detection, identification, and compensation. It is shown that the detection system can be effectively constructed on the basis of a design value, specified by mission requirements, of the unknown parameter in the actual system, and of a degradation mode in the form of a constant bias jump. A suboptimal detection system on the basis of Wald's sequential analysis is developed using the concept of information value and information feedback. The developed system is easily implemented, and demonstrates a performance remarkably close to that of the optimal nonlinear detection system. An invariant transformation is derived to eliminate the effect of nuisance parameters such that the ambiguous identification system can be reduced to a set of disjoint simple hypotheses tests. By application of a technique of decoupled bias estimation in the compensation system the adaptive system can be operated without any complicated reorganization.

  14. Unconventional Coding Technique Applied to Multi-Level Polarization Modulation

    Rutigliano, G. G.; Betti, S.; Perrone, P.

    2016-05-01

    A new technique is proposed to improve information confidentiality in optical-fiber communications without bandwidth consumption. A pseudorandom vectorial sequence was generated by a dynamic system algorithm and used to codify a multi-level polarization modulation based on the Stokes vector. Optical-fiber birefringence, usually considered as a disturbance, was exploited to obfuscate the signal transmission. At the receiver end, the same pseudorandom sequence was generated and used to decode the multi-level polarization modulated signal. The proposed scheme, working at the physical layer, provides strong information security without introducing complex processing and thus latency.

  15. Automation of assertion testing - Grid and adaptive techniques

    Andrews, D. M.

    1985-01-01

    Assertions can be used to automate the process of testing software. Two methods for automating the generation of input test data are described in this paper. One method selects the input values of variables at regular intervals in a 'grid'. The other, adaptive testing, uses assertion violations as a measure of errors detected and generates new test cases based on test results. The important features of assertion testing are that: it can be used throughout the entire testing cycle; it provides automatic notification of error conditions; and it can be used with automatic input generation techniques which eliminate the subjectivity in choosing test data.

  16. Study on Temperature Modulation Techniques for Micro Gas Sensors

    Guangfen Wei; Zhenan Tang; Hongquan Zhang; Yanbing Xue; Jun Yu

    2006-01-01

    The sensitivity and selectivity of gas sensors are related with not only sensing material, but also their operating temperatures. Applying this property, temperature modulation technique has been proposed to improve the selectivity of gas sensors. With a newly developed alumina based micro gas sensor, the sensitivity to CO and CH4 at different operating temperatures was investigated. By modulating the temperature of the sensor at pulse and sine wave modes with different frequencies and amplitudes, the dynamic responses of the sensor were measured and processed. Results show that the modulating waveshape plays an important role in the improvement of selectivity, while the influence of frequency is small at the suitable sampling frequency in the range of 25 mHz~200 mHz.

  17. Adaptive Communication Techniques for the Internet of Things

    Peng Du

    2013-03-01

    Full Text Available The vision for the Internet of Things (IoT demands that material objects acquire communications and computation capabilities and become able to automatically identify themselves through standard protocols and open systems, using the Internet as their foundation. Yet, several challenges still must be addressed for this vision to become a reality. A core ingredient in such development is the ability of heterogeneous devices to communicate adaptively so as to make the best of limited spectrum availability and cope with competition which is inevitable as more and more objects connect to the system. This survey provides an overview of current developments in this area, placing emphasis on wireless sensor networks that can provide IoT capabilities for material objects and techniques that can be used in the context of systems employing low-power versions of the Internet Protocol (IP stack. The survey introduces a conceptual model that facilitates the identification of opportunities for adaptation in each layer of the network stack. After a detailed discussion of specific approaches applicable to particular layers, we consider how sharing information across layers can facilitate further adaptation. We conclude with a discussion of future research directions.

  18. A New Local Adaptive Thresholding Technique in Binarization

    Singh, T Romen; Singh, O Imocha; Sinam, Tejmani; Singh, Kh Manglem

    2012-01-01

    Image binarization is the process of separation of pixel values into two groups, white as background and black as foreground. Thresholding plays a major in binarization of images. Thresholding can be categorized into global thresholding and local thresholding. In images with uniform contrast distribution of background and foreground like document images, global thresholding is more appropriate. In degraded document images, where considerable background noise or variation in contrast and illumination exists, there exists many pixels that cannot be easily classified as foreground or background. In such cases, binarization with local thresholding is more appropriate. This paper describes a locally adaptive thresholding technique that removes background by using local mean and mean deviation. Normally the local mean computational time depends on the window size. Our technique uses integral sum image as a prior processing to calculate local mean. It does not involve calculations of standard deviations as in other ...

  19. New modulation-based watermarking technique for video

    Lemma, Aweke; van der Veen, Michiel; Celik, Mehmet

    2006-02-01

    Successful watermarking algorithms have already been developed for various applications ranging from meta-data tagging to forensic tracking. Nevertheless, it is commendable to develop alternative watermarking techniques that provide a broader basis for meeting emerging services, usage models and security threats. To this end, we propose a new multiplicative watermarking technique for video, which is based on the principles of our successful MASK audio watermark. Audio-MASK has embedded the watermark by modulating the short-time envelope of the audio signal and performed detection using a simple envelope detector followed by a SPOMF (symmetrical phase-only matched filter). Video-MASK takes a similar approach and modulates the image luminance envelope. In addition, it incorporates a simple model to account for the luminance sensitivity of the HVS (human visual system). Preliminary tests show algorithms transparency and robustness to lossy compression.

  20. CSI Feedback-based CS for Underwater Acoustic Adaptive Modulation OFDM System with Channel Prediction

    蒯小燕; 孙海信; 齐洁; 程恩; 许小卡; 郭瑜辉; 陈友淦

    2014-01-01

    In this paper, we investigate the performance of adaptive modulation (AM) orthogonal frequency division multiplexing (OFDM) system in underwater acoustic (UWA) communications. The aim is to solve the problem of large feedback overhead for channel state information (CSI) in every subcarrier. A novel CSI feedback scheme is proposed based on the theory of compressed sensing (CS). We propose a feedback from the receiver that only feedback the sparse channel parameters. Additionally, prediction of the channel state is proposed every several symbols to realize the AM in practice. We describe a linear channel prediction algorithm which is used in adaptive transmission. This system has been tested in the real underwater acoustic channel. The linear channel prediction makes the AM transmission techniques more feasible for acoustic channel communications. The simulation and experiment show that significant improvements can be obtained both in bit error rate (BER) and throughput in the AM scheme compared with the fixed Quadrature Phase Shift Keying (QPSK) modulation scheme. Moreover, the performance with standard CS outperforms the Discrete Cosine Transform (DCT) method.

  1. Feedback of mechanical effectiveness induces adaptations in motor modules during cycling

    Cristiano De Marchis

    2013-04-01

    Full Text Available Recent studies have reported evidence that the motor system may rely on a modular organization, even if this behavior has yet to be confirmed during motor adaptation. The aim of the present study is to investigate the modular motor control mechanisms underlying the execution of pedaling by untrained subjects in different biomechanical conditions. We use the muscle synergies framework to characterize the muscle coordination of 11 subjects pedaling under two different conditions. The first one consists of a pedaling exercise with a strategy freely chosen by the subjects (Preferred Pedaling Technique,PPT, while the second condition constrains the gesture by means of a real time visual feedback of mechanical effectiveness (Effective Pedaling Technique,EPT. Pedal forces, recorded using a pair of instrumented pedals, were used to calculate the Index of Effectiveness, IE. EMG signals were recorded from 8 muscles of the dominant leg and Nonnegative Matrix Factorization was applied for the extraction of muscle synergies. All the synergy vectors, extracted cycle by cycle for each subject, were pooled across subjects and conditions and underwent a 2-dimensional Sammon's non-linear mapping. 7 representative clusters were identified on the Sammon's projection, and the corresponding 8-dimensional synergy vectors were used to reconstruct the repertoire of muscle activation for all subjects and all pedaling conditions (VAF > 0.8 for each individual muscle pattern. Only 5 out of the 7 identified modules were used by the subjects during the PPT pedaling condition, while 2 additional modules were found specific for the pedaling condition EPT. The temporal recruitment of three identified modules was highly correlated with IE. The structure of the identified modules was found similar to that extracted in other studies of human walking, partly confirming the existence of shared and task specific muscle synergies, and providing further evidence on the modularity of

  2. Fuzzy logic based Adaptive Modulation Using Non Data Aided SNR Estimation for OFDM system

    K.SESHADRI SASTRY

    2010-06-01

    Full Text Available As demand for high quality transmission increases increase of spectrum efficiency and an improvement of error performance in wireless communication systems are important . One of the promising approaches to 4G is adaptive OFDM (AOFDM . Fixed modulation systems uses only one type of modulation scheme (or order, so that either performance or capacity should be compromised Adaptive modulated systems are superior to fixed modulated systems, since they change modulation order depending on present SNR. In an adaptive modulation system SNR estimation is important since performance of adaptive modulated system depends of estimated SNR. Non-data-Aided (NDA SNR estimation systems are gaining importance in recent days since they estimate SNR range and requires less data as input .In this paper we propose an adaptive modulated OFDM system which uses NDA(Non-data Aided SNR estimation using fuzzy logic interface.The proposed system is simulated in Matlab 7.4 and The results of computer simulation show the improvement in system capacity .

  3. Adaptive high harmonic generation by spatial light modulation

    Full text: When an intense ultrashort laser pulse interacts with matter, the radiation gets partially converted into integer multiples of its fundamental frequency in a process called high-harmonic generation (HHG). The generated harmonics can extend up to very high orders spanning a wide wavelength range of XUV or soft x-ray radiation. A large bandwidth is beneficial to the generation of sub-femtosecond pulses, but inconvenient for applications like photoelectron spectroscopy. Better control over the process of high-harmonic generation is needed to tailor XUV spectra for specific experimental needs. By application of adaptive pulse shaping methods for the generating laser pulse and the preparation of a suitable HHG setup, a compact, versatile laboratory source of XUV radiation for time-resolved spectroscopy down to the attosecond regime can be constructed. We have already achieved a high level of control over the spectral shape of harmonics by temporal shaping of the 800 nm driver pulse with a deformable mirror. A hollow fiber (split into three segments) is used for phase-matched harmonic generation. Here, we show the first results of HHG with control over the spatial profile of the generating laser pulse to enable the laser to selectively couple into specific fiber modes. This is accomplished using an electrically addressable phase-only spatial light modulator (SLM), controlled by a computer. First, the shaping capabilities of the SLM were tested in a small test setup by focussing a spatially shaped monochromatic laser into a hollow fiber. The fiber output was recorded and could then be optimized by adaptive feedback control. Generating high harmonics inside the fiber reveals that depending on the focusing geometry different fiber modes can be excited resulting in different harmonic spectra for each of the modes. A bimodal spectral structure is visible (a) before optimization due to the presence of at least two different fiber modes. The optimal spatially shaped

  4. Modulation of allele leakiness and adaptive mutability in Escherichia coli

    R. Jayaraman

    2000-08-01

    It is shown that partial phenotypic suppression of two ochre mutations (argE3 and lacZU118) and an amber mutation (in argE) by sublethal concentrations of streptomycin in an rpsL+ (streptomycin-sensitive) derivative of the Escherichia coli strain AB1157 greatly enhances their adaptive mutability under selection. Streptomycin also increases adaptive mutability brought about by the ppm mutation described earlier. Inactivation of recA affects neither phenotypic suppression by streptomycin nor replication-associated mutagenesis but abolishes adaptive mutagenesis. These results indicate a causal relationship between allele leakiness and adaptive mutability.

  5. Modulation Techniques for Biomedical Implanted Devices and Their Challenges

    Salina A. Samad

    2011-12-01

    Full Text Available Implanted medical devices are very important electronic devices because of their usefulness in monitoring and diagnosis, safety and comfort for patients. Since 1950s, remarkable efforts have been undertaken for the development of bio-medical implanted and wireless telemetry bio-devices. Issues such as design of suitable modulation methods, use of power and monitoring devices, transfer energy from external to internal parts with high efficiency and high data rates and low power consumption all play an important role in the development of implantable devices. This paper provides a comprehensive survey on various modulation and demodulation techniques such as amplitude shift keying (ASK, frequency shift keying (FSK and phase shift keying (PSK of the existing wireless implanted devices. The details of specifications, including carrier frequency, CMOS size, data rate, power consumption and supply, chip area and application of the various modulation schemes of the implanted devices are investigated and summarized in the tables along with the corresponding key references. Current challenges and problems of the typical modulation applications of these technologies are illustrated with a brief suggestions and discussion for the progress of implanted device research in the future. It is observed that the prime requisites for the good quality of the implanted devices and their reliability are the energy transformation, data rate, CMOS size, power consumption and operation frequency. This review will hopefully lead to increasing efforts towards the development of low powered, high efficient, high data rate and reliable implanted devices.

  6. Cross-layer combining of power control and adaptive modulation with truncated ARQ for cognitive radios

    CHENG Shi-lun; YANG Zhen

    2008-01-01

    To maximize throughput and to satisfy users' requirements in cognitive radios, a cross-layer optimization problem combining adaptive modulation and power control at the physical layer and truncated automatic repeat request at the medium access control layer is proposed. Simulation results show the combination of power control, adaptive modulation, and truncated automatic repeat request can regulate transmitter powers and increase the total throughput effectively.

  7. History-based Adaptive Modulation for a Downlink Multicast Channel in OFDMA systems

    Wang, Haibo; Schwefel, Hans-Peter; Toftegaard, Thomas Skjødeberg

    2008-01-01

    In this paper we investigated the adaptive modulation strategies for Multicast service in orthogonal frequency division multiple access systems. We defined a Reward function as the performance optimization target and developed adaptive modulation strategies to maximize this Reward function. The...... proposed optimization algorithm varied the instantaneous BER constraint of each mobile Multicast receiver according to its individual cumulated BER, which resulted in a significant Reward gain....

  8. A channel- and QoS-adaptive turbo coded modulation architecture for mobile multimedia communication

    Zuo Jiancun; Song Wentao; Luo Hanwen; Xu Youyun

    2009-01-01

    This paper proposed a cross-layer dual adaptive coded modulation architecture using turbo codes for mobile multimedia communication, which simultaneously adapted to both the varying channel characteristics and the quality of service (QoS) of various mobile multimedia services to increase the average system throughput substantially. A pragmatic channel-adaptive turbo coded modulation scheme, which comes within 2.5dB of the Shannon limit, was optimally designed, and then a QoS-adaptive scheme was superimposed to build the dual adaptive architecture. Simulation results show that the novel dual adaption reduces the difference with the fading channel capacity to 2dB when assuming different services occur in equal probability and the service duration follows the exponential distribution.

  9. Sensor Web Dynamic Measurement Techniques and Adaptive Observing Strategies

    Talabac, Stephen J.

    2004-01-01

    Sensor Web observing systems may have the potential to significantly improve our ability to monitor, understand, and predict the evolution of rapidly evolving, transient, or variable environmental features and events. This improvement will come about by integrating novel data collection techniques, new or improved instruments, emerging communications technologies and protocols, sensor mark-up languages, and interoperable planning and scheduling systems. In contrast to today's observing systems, "event-driven" sensor webs will synthesize real- or near-real time measurements and information from other platforms and then react by reconfiguring the platforms and instruments to invoke new measurement modes and adaptive observation strategies. Similarly, "model-driven" sensor webs will utilize environmental prediction models to initiate targeted sensor measurements or to use a new observing strategy. The sensor web concept contrasts with today's data collection techniques and observing system operations concepts where independent measurements are made by remote sensing and in situ platforms that do not share, and therefore cannot act upon, potentially useful complementary sensor measurement data and platform state information. This presentation describes NASA's view of event-driven and model-driven Sensor Webs and highlights several research and development activities at the Goddard Space Flight Center.

  10. Analytical evaluation of adaptive-modulation-based opportunistic cognitive radio in nakagami-m fading channels

    Chen, Yunfei

    2012-09-01

    The performance of adaptive modulation for cognitive radio with opportunistic access is analyzed by considering the effects of spectrum sensing, primary user (PU) traffic, and time delay for Nakagami- m fading channels. Both the adaptive continuous rate scheme and the adaptive discrete rate scheme are considered. Numerical examples are presented to quantify the effects of spectrum sensing, PU traffic, and time delay for different system parameters. © 1967-2012 IEEE.

  11. Adaptive capacity to bacterial diet modulates aging in C. elegans

    Pang, Shanshan; Curran, Sean P.

    2014-01-01

    Diet has a substantial impact on cellular metabolism and physiology. Animals must sense different food sources and utilize distinct strategies to adapt to diverse diets. Here we show that C. elegans lifespan is regulated by their adaptive capacity to different diets, which is controlled by alh-6, a conserved proline metabolism gene. alh-6 mutants age prematurely when fed an E. coli OP50 but not HT115 diet. Remarkably, this diet-dependent aging phenotype is determined by exposure to food durin...

  12. Indirect techniques for adaptive input-output linearization of non-linear systems

    Teel, Andrew; Kadiyala, Raja; Kokotovic, Peter; Sastry, Shankar

    1991-01-01

    A technique of indirect adaptive control based on certainty equivalence for input output linearization of nonlinear systems is proven convergent. It does not suffer from the overparameterization drawbacks of the direct adaptive control techniques on the same plant. This paper also contains a semiindirect adaptive controller which has several attractive features of both the direct and indirect schemes.

  13. Welding techniques development of CLAM steel for Test Blanket Module

    Fabrication techniques for Test Blanket Module (TBM) with CLAM are being under development. Effect of surface preparation on the HIP diffusion bonding joints was studied and good joints with Charpy impact absorbed energy close to that of base metal have been obtained. The mechanical properties test showed that effect of HIP process on the mechanical properties of base metal was little. Uniaxial diffusion bonding experiments were carried out to study the effect of temperature on microstructure and mechanical properties. And preliminary experiments on Electron Beam Welding (EBW), Tungsten Inert Gas (TIG) Welding and Laser Beam Welding (LBW) were performed to find proper welding techniques to assemble the TBM. In addition, the thermal processes assessed with a Gleeble thermal-mechanical machine were carried out as well to assist the fusion welding research.

  14. A novel adaptive modulation and coding strategy based on partial feedback for enhanced MBMS network

    SHENG Yu; PENG Mu-gen; WANG Wen-bo

    2008-01-01

    The difference in link condition of broadcast/multicast users and the limitation of uplink resource, make itdifficult to utilize adaptive modulation and coding (AMC) in theenhanced multimedia broadcast and multicast service (E-MBMS)network. To obtain the improvement of system throughput, thisstudy proposes an adaptive modulation and coding schemebased on partial feedback, by which only partial users whosechannel qualities are lower than the system threshold need tomake a response to the modulation coding scheme (MCS)adaptation procedure. By this investigation, an adaptive schemecan be introduced in the E-MBMS network. Both the theoreticalanalysis and simulation results demonstrate the efficiency of theproposed strategy, in which the performance is close to the idealone and has a significant throughput improvement whencompared with that of the fixed MCS transmission scheme.

  15. Intensity Modulated Radiation Therapy. Development of the technique

    Full text: Introduction: Intensity Modulated Radiation Therapy (IMRT) is a result of advances in computer sciences that allowed the development of new technology related to planning and radiation therapy. IMRT was developed to homogenize the dose in the target volumes and decrease the dose in the surrounding healthy tissue. Using a software with high calculation capacity a simultaneous irradiation with different doses in a given volume is achieved. IMRT is based on internal planning. Material and methods: 628 patients were treated with IMRT in prostate lesions, head and neck, breast, thorax, abdomen and brain since August 2008. The software for IMRT is the XIO CMS and the accelerator used is a Varian Clinac 6 / 100. IMRT requires a first simulation, where immobilization systems are selected (mats, thermoplastic masks, among others) and the demarcation of the target structures, healthy tissue and dose prescription by a tattoo. Images of CT / MRI are merged when necessary. Once the system made the treatment optimization, this one is regulated by modulators. These are produced by numerical control machines from digital files produced by software. In a second modulation the planned irradiation is checked and tattoo is carried out according with this. We have a strict process of quality assurance to assess the viability of the plan before its implementation. We use the Map Check it possible to compare the dose on the central axis and the distribution in the whole plane regarding to that generated by the planning system. From 03/2008 the virtual simulation process was implemented integrating the described stages. Results and Conclusions: IMRT is a complex technique. The meticulous planning, implementation of process and quality control allows the use of this technique in a reliable and secure way. With IMRT we achieved a high level of dose conformation, less irradiation of healthy tissue, lower rates of complications and the dose escalation for some tumors. (authors)

  16. A Module for Adaptive Course Configuration and Assessment in Moodle

    Limongelli, Carla; Sciarrone, Filippo; Temperini, Marco; Vaste, Giulia

    Personalization and Adaptation are among the main challenges in the field of e-learning, where currently just few Learning Management Systems, mostly experimental ones, support such features. In this work we present an architecture that allows Moodle to interact with the Lecomps system, an adaptive learning system developed earlier by our research group, that has been working in a stand-alone modality so far. In particular, the Lecomps responsibilities are circumscribed to the sole production of personalized learning objects sequences and to the management of the student model, leaving to Moodle all the rest of the activities for course delivery. The Lecomps system supports the "dynamic" adaptation of learning objects sequences, basing on the student model, i.e., learner's Cognitive State and Learning Style. Basically, this work integrates two main Lecomps tasks into Moodle, to be directly managed by it: Authentication and Quizzes.

  17. High Performance ZVT with Bus Clamping Modulation Technique for Single Phase Full Bridge Inverters

    Xia, Yinglai; Ayyanar, Raja

    2016-03-20

    This paper proposes a topology based on bus clamping modulation and zero-voltage-transition (ZVT) technique to realize zero-voltage-switching (ZVS) for all the main switches of the full bridge inverters, and inherent ZVS and/or ZCS for the auxiliary switches. The advantages of the strategy include significant reduction in the turn-on loss of the ZVT auxiliary switches which typically account for a major part of the total loss in other ZVT circuits, and reduction in the voltage ratings of auxiliary switches. The modulation scheme and the commutation stages are analyzed in detail. Finally, a 1kW, 500 kHz switching frequency inverter of the proposed topology using SiC MOSFETs has been built to validate the theoretical analysis. The ZVT with bus clamping modulation technique of fixed timing and adaptive timing schemes are implemented in DSP TMS320F28335 resulting in full ZVS for the main switches in the full bridge inverter. The proposed scheme can save up to 33 % of the switching loss compared with no ZVT case.

  18. Correction of respiratory motion for IMRT using aperture adaptive technique and visual guidance: A feasibility study

    Intensity-modulated radiation therapy (IMRT) utilizes nonuniform beam profile to deliver precise radiation doses to a tumor while minimizing radiation exposure to surrounding normal tissues. However, the problem of intrafraction organ motion distorts the dose distribution and leads to significant dosimetric errors. In this research, we applied an aperture adaptive technique with a visual guiding system to toggle the problem of respiratory motion. A homemade computer program showing a cyclic moving pattern was projected onto the ceiling to visually help patients adjust their respiratory patterns. Once the respiratory motion becomes regular, the leaf sequence can be synchronized with the target motion. An oscillator was employed to simulate the patient's breathing pattern. Two simple fields and one IMRT field were measured to verify the accuracy. Preliminary results showed that after appropriate training, the amplitude and duration of volunteer's breathing can be well controlled by the visual guiding system. The sharp dose gradient at the edge of the radiation fields was successfully restored. The maximum dosimetric error in the IMRT field was significantly decreased from 63% to 3%. We conclude that the aperture adaptive technique with the visual guiding system can be an inexpensive and feasible alternative without compromising delivery efficiency in clinical practice

  19. Fabrication techniques development of test blanket module based on CLAM

    The Reduced Activation Ferritic/Martensitic steels (RAFMs) are considered as the primary candidate structural material for the DEMO fusion reactor and the first fusion power plant. China Low Activation Martensitic (CLAM) steel, a version of RAFMs, is being developed in ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences), under wide collaboration with many institutes and universities in China and overseas. The designs of FDS (Fusion Design Study) series liquid LiPb blankets for fusion reactors and corresponding Dual Functional Lithium Lead (DFLL) Test Blanket Module (TBM) in International Thermonuclear Experimental Reactor (ITER) are being carried out in ASIPP. And CLAM steel is chosen as the primary candidate structural material in these designs. So the fabrication techniques for DFLL TBM with CLAM are or urgently needed to be studied in detail. The fabrication of DFLL TBM mainly includes the manufacturing of the First Wall (FW), the Cooling Plates (CP) and the joining of the FW and CPs. Currently, solid Hot Isostatic Pressing (HIP) bonding and uniaxial diffusion bonding method are the most promising candidate fabrication method for the FW and CP. Experiments of HIP and unixial diffusion bonding of CLAM/CLAM were carried out and good joints were obtained. As for the joining technique of FW and CPs, the fusion welding techniques such as Tungsten Inert Gas welding, Laser welding and Electron Beam welding are candidates. Preliminary experiments on these welding techniques were performed. The simulation of thermal process by Gleeble 2000 was also carried out. Results of these experiments are summarized and further R and D plan on blanket fabrication techniques is also stated. (authors)

  20. BER Analysis with Adaptive Modulation Coding in MIMO-OFDM for WiMAX using GNU Radio

    B. Siva Kumar Reddy

    2014-11-01

    Full Text Available This paper explores how MIMO increases channel capacity and how the fundamental characteristics of a MIMO system can create significant test challenges. Spatial modulation (SM is the latest developed modulation method in the field of communication. The latest research on this shows that SM is useful to achieve the multiplexing gain for the single antenna system, this avoids the inter-channel interference but the spatial modulation is inherently unable to get transmit-diversity. In other words, SM is a novel modulation technique which combines the high multiplexing gain provided by the spatial modulation and transmit-diversity gain, given by the space time block codes (STBCs technology. Different space-time block coding (STBC schemes including Alamouti’s STBC for 2 transmit antennas as well as orthogonal STBC (OSTBC for 3 and 4 transmit antennas are explored. The result of using these MIMO techniques is higher data rate or longer transmit range without requiring additional bandwidth or transmit power. This paper presents a detailed study of diversity coding for MIMO systems. In addition, adaptive modulation and coding (AMC technique in conjunction with MIMO techniques constitute a technological breakthrough that greatly helps in satisfying the ever increasing demands of wireless networks. This paper presents a performance study of Mobile WiMAX networks based on MIMO and AMC perspectives. It also describes how to implement WiMAX PHY with MIMO on software defined radio (SDR experimental setup with the help of USRP N210 as hardware and GNU Radio as software platforms.

  1. Adaptive capacity to bacterial diet modulates aging in C. elegans.

    Pang, Shanshan; Curran, Sean P

    2014-02-01

    Diet has a substantial impact on cellular metabolism and physiology. Animals must sense different food sources and utilize distinct strategies to adapt to diverse diets. Here we show that Caenorhabditis elegans lifespan is regulated by their adaptive capacity to different diets, which is controlled by alh-6, a conserved proline metabolism gene. alh-6 mutants age prematurely when fed an Escherichia coli OP50 but not HT115 diet. Remarkably, this diet-dependent aging phenotype is determined by exposure to food during development. Mechanistically, the alh-6 mutation triggers diet-induced mitochondrial defects and increased generation of ROS, likely due to accumulation of its substrate 1-pyrroline-5-carboxylate. We also identify that neuromedin U receptor signaling is essential for diet-induced mitochondrial changes and premature aging. Moreover, dietary restriction requires alh-6 to induce longevity. Collectively, our data reveal a homeostatic mechanism that animals employ to cope with potential dietary insults and uncover an example of lifespan regulation by dietary adaptation. PMID:24440036

  2. Adaptive Remote-Sensing Techniques Implementing Swarms of Mobile Agents

    Cameron, S.M.; Loubriel, G.M.; Rbinett, R.D. III; Stantz, K.M.; Trahan, M.W.; Wagner, J.S.

    1999-04-01

    This paper focuses on our recent work at Sandia National Laboratories toward engineering a physics-based swarm of mobile vehicles for distributed sensing applications. Our goal is to coordinate a sensor array that optimizes sensor coverage and multivariate signal analysis by implementing artificial intelligence and evolutionary computational techniques. These intelligent control systems integrate both globally operating decision-making systems and locally cooperative information-sharing modes using genetically-trained neural networks. Once trained, neural networks have the ability to enhance real-time operational responses to dynamical environments, such as obstacle avoidance, responding to prevailing wind patterns, and overcoming other natural obscurants or interferences (jammers). The swarm realizes a collective set of sensor neurons with simple properties incorporating interactions based on basic community rules (potential fields) and complex interconnecting functions based on various neural network architectures, Therefore, the swarm is capable of redundant heterogeneous measurements which furnishes an additional degree of robustness and fault tolerance not afforded by conventional systems, while accomplishing such cognitive tasks as generalization, error correction, pattern recognition, and sensor fission. The robotic platforms could be equipped with specialized sensor devices including transmit/receive dipole antennas, chemical or biological sniffers in combination with recognition analysis tools, communication modulators, and laser diodes. Our group has been studying the collective behavior of an autonomous, multi-agent system applied to emerging threat applications. To accomplish such tasks, research in the fields of robotics, sensor technology, and swarms are being conducted within an integrated program. Mission scenarios under consideration include ground penetrating impulse radar (GPR) for detection of under-ground structures, airborne systems, and plume

  3. Evaluation on lung cancer patients' adaptive planning of TomoTherapy utilising radiobiological measures and Planned Adaptive module.

    Su, Fan-Chi; Shi, Chengyu; Mavroidis, Panayiotis; Rassiah-Szegedi, Prema; Papanikolaou, Niko

    2009-01-01

    Adaptive radiation therapy is a promising concept that allows individualised, dynamic treatment planning based on feedback of measurements. The TomoTherapy Planned Adaptive application, integrated to the helical TomoTherapy planning system, enables calculation of actual dose delivered to the patient for each treatment fraction according to the pretreatment megavoltage computed tomography (MVCT) scan and image registration. As a result, new fractionation treatment plans are available if correction is necessary. In order to evaluate therealclinicaleffect,biologicaldoseis preferred to physical dose. A biological parameter, biologically effective uniform dose ([Formula: see text]), has the advantages of not only reporting delivered dose but also facilitating the analysis of dose-response relations, which link radiation dose to the clinical effect. Therefore, in this study, four lung patients' adaptive plans were evaluated using the [Formula: see text] in addition to physical doses estimated from the TomoTherapy Planned Adaptive module. Higher complication-free tumour control probability (P(+))(of about 8%) was observed in patients treated with larger dose-per-fraction by using the [Formula: see text] in addition to the physical dose. Moreover, a significant increase of 13.2% in the P(+) for the adaptive TomoTherapy plan in one of the lung cancer patients was also observed, which indicates the clinical benefit of adaptive TomoTherapy. PMID:20376282

  4. ADAPTIVE MODULATION AND POWER CONTROL FOR THROUGHPUT ENHANCEMENT IN COGNITIVE RADIOS

    2008-01-01

    To regulate the transmit-power and enhance the total throughput, a novel Transmit Power Control Game (TPCG) algorithm and an adaptive Modulation TPCG (M-TPCG) algorithm which combine bandwidth allocation, adaptive modulation and transmit-power control based on Space Time Block Coding (STBC) OFDM-CDMA system are designed and a cross-layer framework of database sharing is proposed. Simulation results show that the TPCG algorithm can regulate their transmitter powers and enhance the total throughput effectively, M-TPCG algorithm can achieve maximal system throughput. The performance of the cognitive radio system is improved obviously.

  5. Configurable multiplier modules for an adaptive computing system

    O. A. Pfänder

    2006-01-01

    Full Text Available The importance of reconfigurable hardware is increasing steadily. For example, the primary approach of using adaptive systems based on programmable gate arrays and configurable routing resources has gone mainstream and high-performance programmable logic devices are rivaling traditional application-specific hardwired integrated circuits. Also, the idea of moving from the 2-D domain into a 3-D design which stacks several active layers above each other is gaining momentum in research and industry, to cope with the demand for smaller devices with a higher scale of integration. However, optimized arithmetic blocks in course-grain reconfigurable arrays as well as field-programmable architectures still play an important role. In countless digital systems and signal processing applications, the multiplication is one of the critical challenges, where in many cases a trade-off between area usage and data throughput has to be made. But the a priori choice of word-length and number representation can also be replaced by a dynamic choice at run-time, in order to improve flexibility, area efficiency and the level of parallelism in computation. In this contribution, we look at an adaptive computing system called 3-D-SoftChip to point out what parameters are crucial to implement flexible multiplier blocks into optimized elements for accelerated processing. The 3-D-SoftChip architecture uses a novel approach to 3-dimensional integration based on flip-chip bonding with indium bumps. The modular construction, the introduction of interfaces to realize the exchange of intermediate data, and the reconfigurable sign handling approach will be explained, as well as a beneficial way to handle and distribute the numerous required control signals.

  6. On the feedback error compensation for adaptive modulation and coding scheme

    Choi, Seyeong

    2011-11-25

    In this paper, we consider the effect of feedback error on the performance of the joint adaptive modulation and diversity combining (AMDC) scheme which was previously studied with an assumption of perfect feedback channels. We quantify the performance of two joint AMDC schemes in the presence of feedback error, in terms of the average spectral efficiency, the average number of combined paths, and the average bit error rate. The benefit of feedback error compensation with adaptive combining is also quantified. Selected numerical examples are presented and discussed to illustrate the effectiveness of the proposed feedback error compensation strategy with adaptive combining. Copyright (c) 2011 John Wiley & Sons, Ltd.

  7. Novel Modulation Techniques using Isomers as Messenger Molecules for Molecular Communication via Diffusion

    Kim, Na-Rae; Chae, Chan-Byoung

    2012-01-01

    In this paper, we propose novel modulation techniques using isomers as messenger molecules for nano communication via diffusion. To evaluate achievable rate performance, we compare the proposed techniques with concentration-based and molecular-type-based methods. Analytical and numerical results confirm that the proposed modulation techniques achieve higher data transmission rate performance than conventional insulin based concepts.

  8. Latency Considerations for Adaptive Modulation in an Interference-free Slow Rayleigh Fading Channel

    Torrance, J; Hanzo, L.

    1997-01-01

    Adaptive modulation exploits the time-variant channel capacity uctuation of fading channels using a range of different modem modes according to Equation 1 and Table 1. This is achieved at the cost of some latency penalty, which is quantified in this treatise and mitigated by frequency hopping.

  9. ARQ strategies for MIMO eigenmode transmission with adaptive modulation and coding

    De Carvalho, Elisabeth; Popovski, Petar

    Packet retransmission strategies are presented for MIMO eigenmode transmission where adaptive modulation and coding (AMC) is implemented. The retransmission design is based on weighted linear MMSE. It includes the transmit and receiver filter, the power and eigenmode allocation and AMC level when...

  10. The optimal configuration of photovoltaic module arrays based on adaptive switching controls

    Highlights: • We propose a strategy for determining the optimal configuration of a PV array. • The proposed strategy was based on particle swarm optimization (PSO) method. • It can identify the optimal module array connection scheme in the event of shading. • It can also find the optimal connection of a PV array even in module malfunctions. - Abstract: This study proposes a strategy for determining the optimal configuration of photovoltaic (PV) module arrays in shading or malfunction conditions. This strategy was based on particle swarm optimization (PSO). If shading or malfunctions of the photovoltaic module array occur, the module array immediately undergoes adaptive reconfiguration to increase the power output of the PV power generation system. First, the maximal power generated at various irradiation levels and temperatures was recorded during normal array operation. Subsequently, the irradiation level and module temperature, regardless of operating conditions, were used to recall the maximal power previously recorded. This previous maximum was compared with the maximal power value obtained using the maximum power point tracker to assess whether the PV module array was experiencing shading or malfunctions. After determining that the array was experiencing shading or malfunctions, PSO was used to identify the optimal module array connection scheme in abnormal conditions, and connection switches were used to implement optimal array reconfiguration. Finally, experiments were conducted to assess the strategy for identifying the optimal reconfiguration of a PV module array in the event of shading or malfunctions

  11. An adapted modulation transfer function for x-ray backscatter radiography by selective detection

    Sabri, Nissia; Dugan, Edward T.; Jacobs, Alan M.; Shedlock, Daniel

    2007-09-01

    The Modulation Transfer Function (MTF) is a quantitative function based on frequency resolution that characterizes imaging system performance. In this study, a new MTF methodology is investigated for application to Radiography by Selective Detection (RSD), an enhanced single-side x-ray Compton backscatter imaging (CBI) technique which detects selected scatter components. The RSD imaging modality is a unique type of real-time radiography that uses a set of fin and sleeve collimators to preferentially select different components of the x-ray backscattered field. Radiography by selective detection has performed successfully in different non-destructive evaluation (NDE) applications. A customized RSD imaging system was built at the University of Florida for inspection of the space shuttle external tank spray-on foam insulation (SOFI). The x-ray backscatter RSD imaging system has been successfully used for crack and corrosion detection in a variety of materials. The conventional transmission x-ray image quality characterization tools do not apply for RSD because of the different physical process involved. Thus, the main objective of this project is to provide an adapted tool for dynamic evaluation of RSD system image quality. For this purpose, an analytical model of the RSD imaging system response is developed and supported. Two approaches are taken for the MTF calculations: one using the Fourier Transform of a line spread function and the other one using a sine function pattern. Calibration and test targets are then designed according to this proposed model. A customized Matlab code using image contrast and digital curve recognition is developed to support the experimental data and provide the Modulation Transfer Functions for RSD.

  12. Adaptive Landmark-Based Navigation System Using Learning Techniques

    Zeidan, Bassel; Dasgupta, Sakyasingha; Wörgötter, Florentin;

    2014-01-01

    . Inspired by this, we develop an adaptive landmark-based navigation system based on sequential reinforcement learning. In addition, correlation-based learning is also integrated into the system to improve learning performance. The proposed system has been applied to simulated simple wheeled and more complex...

  13. Intensity-modulated linear-frequency-modulated continuous-wave lidar for distributed media: fundamentals of technique

    Batet Torrell, Óscar; Dios Otín, Víctor Federico; Comerón Tejero, Adolfo; Agishev, Ravil R.

    2010-01-01

    We analyze the intensity-modulation frequency-modulated continuous-wave (FMCW) technique for lidar remote sensing in the context of its application to distributed media. The goal of the technique is the reproduction of the sounded-medium profile along the emission path. A conceptual analysis is carried out to show the problems the basic version of the method presents for this application. The principal point is the appearance of a bandpass filtering effect, which seems to hinder its use in...

  14. Optimizing Power and Buffer Congestion on Wireless Sensor Nodes Using CAP (Coordinated Adaptive Power Management Technique

    Gauri Joshi

    2011-05-01

    Full Text Available Limited hardware capabilities and very limited battery power supply are the two main constraints thatarise because of small size and low cost of the wireless sensor nodes. Power optimization is highlydesired at all the levels in order to have a long lived Wireless Sensor Network (WSN. Prolonging the lifespan of the network is the prime focus in highly energy constrained wireless sensor networks. Sufficientnumber of active nodes can only ensure proper coverage of the sensing field and connectivity of thenetwork. If large number of wireless sensor nodes get their batteries depleted over a short time span thenit is not possible to maintain the network. In order to have long lived network it is mandatory to havelong lived sensor nodes and hence power optimization at node level becomes equally important as poweroptimization at network level. In this paper need for a dynamically adaptive sensor node is signified inorder to optimize power at individual nodes along with the reduction in data loss due to buffercongestion.We have analyzed a sensor node with fixed service rate (processing rate and transmission rate and asensor node with variable service rates for its power consumption and data loss in small sized buffersunder varying traffic (workload conditions. For variable processing rate Dynamic Voltage FrequencyScaling (DVFS technique is considered and for variable transmission rate Dynamic Modulation Scaling(DMS technique is considered. Comparing the results of a dynamically adaptive sensor node with thatof a fixed service rate sensor node shows improvement in the lifetime of node as well as reduction in thedata loss due to buffer congestion. Further we have tried to coordinate the service rates of computationunit and communication unit on a sensor node which give rise to Coordinated Adaptive Power (CAPmanagement. The main objective of CAP Management is to save the power during normal periods andreduce the data loss due to buffer congestion (overflow

  15. Adaptive Communication Techniques for the Internet of Things

    Peng Du; George Roussos

    2013-01-01

    The vision for the Internet of Things (IoT) demands that material objects acquire communications and computation capabilities and become able to automatically identify themselves through standard protocols and open systems, using the Internet as their foundation. Yet, several challenges still must be addressed for this vision to become a reality. A core ingredient in such development is the ability of heterogeneous devices to communicate adaptively so as to make the best of limited spectrum a...

  16. Techniques for valuing adaptive capacity in flood risk management

    Brisley, Rachel; Wylde, Richard; Lamb, Rob; Cooper, Jonathan; Sayers, Paul; Hall, Jim

    2015-01-01

    Flood and coastal erosion risk management has always faced the challenge of decision making in the face of multiple uncertainties relating to the climate, the economy and society. Traditionally, this has been addressed by adopting a precautionary approach that seeks to protect against a reasonable worst case. However, a managed adaptive approach can offer advantages. The benefits include improved resilience to negative changes, enabling opportunities from positive changes and greater cost eff...

  17. Interesting Metrics Based Adaptive Prediction Technique for Knowledge Discovery

    G. Anbukkarasy; N. Sairam

    2013-01-01

    Prediction is considered as an important factor to predict the future results from the existing information. Decision tree methodology is widely used for predicting the results. But this is not efficient to handle the large, heterogeneous or multi-featured type of data sources. So an adaptive prediction method is proposed by combining the statistical analysis approach of the data mining methods along with the decision tree prediction methodology. So when dealing with large and multi-server ba...

  18. Nuclear Technology. Course 26: Nondestructive Examination (NDE) Techniques I. Module 26-3, Hydrostatic Tests.

    Pelton, Rick; Espy, John

    This third in a series of seven modules for a course titled Nondestructive Examination (NDE) Techniques I describes the principles and practices associated with hydrostatic testing. The module follows a typical format that includes the following sections: (1) introduction, (2) module prerequisites, (3) objectives, (4) notes to instructor/student,…

  19. SEMiX and SKYPER an Intelligent IGBT Module with Adaptable Driver

    MartinFreyberg; MarkusHermwille; Uk-SongHong; JensLi

    2004-01-01

    Modern power converter designs need compact IGBT modules with simple interfaces for costefficient power solutions.Low overall height.separate AC and DC terminals on eaeh side,driver access on top are recent market requirements for modern power nmdules.This leads to the birth of SEMiX-a module platform with the right answer to these requirements.Moreover.this paper highlights also a new driver solution for modules-SKYPER-a simple add-on gate driver with basic driving and protection funetions.Its adaptation to modules-in this article through an example with SEMiX-is tested suecessfully.SEMiX and SKYPER behave like an IPM but offer more flexibilitv to control switching characteristics.presenting a convenient building block for modular inverter solutions.

  20. Combining Adaptive Coding and Modulation With Hierarchical Modulation in Satcom Systems

    Méric, Hugo; Lacan, Jérôme; Arnal, Fabrice; Lesthievent, Guy; Boucheret, Marie-Laure

    2013-01-01

    We investigate the design of a broadcast system in order to maximise the throughput. This task is usually challenging due to the channel variability. Forty years ago, Cover introduced and compared two schemes: time sharing and superposition coding. Even if the second scheme was proved to be optimal for some channels, modern satellite communications systems such as DVB-SH and DVB-S2 mainly rely on time sharing strategy to optimize the throughput. They consider hierarchical modulation, a practi...

  1. Combining Adaptive Coding and Modulation with Hierarchical Modulation in Satcom Systems

    Meric, Hugo; Arnal, Fabrice; Lesthievent, Guy; Boucheret, Marie-Laure

    2011-01-01

    We investigate the design of a broadcast system in order to maximise the throughput. This task is usually challenging due to the channel variability. Forty years ago, Cover introduced and compared two schemes: time sharing and superposition coding. Even if the second scheme was proved to be optimal for some channels, modern satellite communications systems such as DVB-SH and DVB-S2 mainly rely on time sharing strategy to optimize the throughput. They consider hierarchical modulation, a practical implementation of superposition coding, but only for unequal error protection or backward compatibility purposes. We propose in this article to combine time sharing and hierarchical modulation together and show how this scheme can improve the performance in terms of available rate. We introduce the hierarchical 16-APSK to boost the performance of the DVB-S2 standard. We also evaluate various strategies to group the receivers in pairs when using hierarchical modulation. Finally, we show in a realistic use case based on...

  2. Some failure modes and analysis techniques for terrestrial solar cell modules

    Shumka, A.; Stern, K. H.

    1978-01-01

    Analysis data are presented on failed/defective silicon solar cell modules of various types and produced by different manufacturers. The failure mode (e.g., internal short and open circuits, output power degradation, isolation resistance degradation, etc.) are discussed in detail and in many cases related to the type of technology used in the manufacture of the modules; wherever applicable, appropriate corrective actions are recommended. Consideration is also given to some failure analysis techniques that are applicable to such modules, including X-ray radiography, capacitance measurement, cell shunt resistance measurement by the shadowing technique, steady-state illumination test station for module performance illumination, laser scanning techniques, and the SEM.

  3. Process, Voltage and Temperature Compensation Technique for Cascode Modulated PAs

    Sira, Daniel; Larsen, Torben

    2013-01-01

    represents a transistor level model (empirical model) of the cascode modulated PA, is utilized in a PA analog predistorter. The analog predistorter linearizes and compensates for PVT variation of the cascode modulated PA. The empirical model is placed in the negative feedback of an operational......This paper presents a process, voltage and temperature (PVT) compensation method for a cascode modulated polar power amplifier (PA). It is shown that it is possible to create a baseband replica circuit of the PA that has the same AM-AM nonlinearity as the PA itself. The replica circuit, that...

  4. Fast Spectral Velocity Estimation Using Adaptive Techniques: In-Vivo Results

    Gran, Fredrik; Jakobsson, Andreas; Udesen, Jesper; Jensen, Jørgen Arendt

    Adaptive spectral estimation techniques are known to provide good spectral resolution and contrast even when the observation window(OW) is very sbort. In this paper two adaptive techniques are tested and compared to the averaged perlodogram (Welch) for blood velocity estimation. The Blood Power...... spectral Capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slowtime and depth. The Blood Amplitude and Phase Estimation technique (BAPES) is based on finding a set of matched filters (one for each velocity component of interest) and filtering...... the blood process over slow-time and averaging over depth to find the power spectral density estimate. In this paper, the two adaptive methods are explained, and performance Is assessed in controlled steady How experiments and in-vivo measurements. The three methods were tested on a circulating How...

  5. Open-Loop Wide-Bandwidth Phase Modulation Techniques

    Nitin Nidhi

    2011-01-01

    Full Text Available The ever-increasing growth in the bandwidth of wireless communication channels requires the transmitter to be wide-bandwidth and power-efficient. Polar and outphasing transmitter topologies are two promising candidates for such applications, in future. Both these architectures require a wide-bandwidth phase modulator. Open-loop phase modulation presents a viable solution for achieving wide-bandwidth operation. An overview of prior art and recent approaches for phase modulation is presented in this paper. Phase quantization noise cancellation was recently introduced to lower the out-of-band noise in a digital phase modulator. A detailed analysis on the impact of timing and quantization of the cancellation signal is presented. Noise generated by the transmitter in the receive band frequency poses another challenge for wide-bandwidth transmitter design. Addition of a noise transfer function notch, in a digital phase modulator, to reduce the noise in the receive band during phase modulation is described in this paper.

  6. Adaptive Modulation with Best User Selection over Non-Identical Nakagami Fading Channels

    Rao, Anlei

    2012-09-08

    In this paper, we analyze the performance of adaptive modulation with single-cell multiuser scheduling over independent but not identical distributed (i.n.i.d.) Nakagami fading channels. Closed-form expressions are derived for the average channel capacity, spectral efficiency, and bit-error-rate (BER) for both constant-power variable-rate and variable-power variable-rate uncoded M-ary quadrature amplitude modulation (M-QAM) schemes. We also study the impact of time delay on the average BER of adaptive M-QAM. Selected numerical results show that the multiuser diversity brings a considerably better performance even over i.n.i.d. fading environments.

  7. Multiuser Diversity with Adaptive Modulation in Non-Identically Distributed Nakagami Fading Environments

    Rao, Anlei

    2012-09-08

    In this paper, we analyze the performance of adaptive modulation with single-cell multiuser scheduling over independent but not identical distributed (i.n.i.d.) Nakagami fading channels. Closed-form expressions are derived for the average channel capacity, spectral efficiency, and bit-error-rate (BER) for both constant-power variable-rate and variable-power variable-rate uncoded/coded M-ary quadrature amplitude modulation (M-QAM) schemes. We also study the impact of time delay on the average BER of adaptive M-QAM. Selected numerical results show that the multiuser diversity brings a considerably better performance even over i.n.i.d. fading environments.

  8. SU-E-J-254: Utility of Pinnacle Dynamic Planning Module Utilizing Deformable Image Registration in Adaptive Radiotherapy

    Purpose For certain highly conformal treatment techniques, changes in patient anatomy due to weight loss and/or tumor shrinkage can result in significant changes in dose distribution. Recently, the Pinnacle treatment planning system added a Dynamic Planning module utilizing Deformable Image Registration (DIR). The objective of this study was to evaluate the effectiveness of this software in adapting to altered anatomy and adjusting treatment plans to account for it. Methods We simulated significant tumor response by changing patient thickness and altered chin positions using a commercially-available head and neck (H and N) phantom. In addition, we studied 23 CT image sets of fifteen (15) patients with H and N tumors and eight (8) patients with prostate cancer. In each case, we applied deformable image registration through Dynamic Planning module of our Pinnacle Treatment Planning System. The dose distribution of the original CT image set was compared to the newly computed dose without altering any treatment parameter. Result was a dose if we did not adjust the plan to reflect anatomical changes. Results For the H and N phantom, a tumor response of up to 3.5 cm was correctly deformed by the Pinnacle Dynamic module. Recomputed isodose contours on new anatomies were within 1 mm of the expected distribution. The Pinnacle system configuration allowed dose computations resulting from original plans on new anatomies without leaving the planning system. Original and new doses were available side-by-side with both CT image sets. Based on DIR, about 75% of H and N patients (11/15) required a re-plan using new anatomy. Among prostate patients, the DIR predicted near-correct bladder volume in 62% of the patients (5/8). Conclusions The Dynamic Planning module of the Pinnacle system proved to be an accurate and useful tool in our ability to adapt to changes in patient anatomy during a course of radiotherapy

  9. Adaptive micro-optical phase modulators based on liquid crystal technology

    Algorri Genaro, José Francisco

    2015-01-01

    This thesis began with the project “Advanced Devices of Liquid Crystal and Electroluminescent Organic Diodes. Hybrid Applications for 3D Vision” funded by the Spanish government. The goal of this project was the development of optical devices to achieve 3D vision in portable devices without glasses or external elements. In order to achieve the goals of this project, solutions based on liquid crystal are considered. Specifically, adaptive micro-optical phase modulators based on liquid crystal ...

  10. An adaptive range-query optimization technique with distributed replicas

    Sayar Ahmet; Pierce Marlon; Fox C.Geoffrey

    2014-01-01

    Replication is an approach often used to speed up the execution of queries submitted to a large dataset. A compile-time/run-time approach is presented for minimizing the response time of 2-dimensional range when a distributed replica of a dataset exists. The aim is to partition the query payload (and its range) into subsets and distribute those to the replica nodes in a way that minimizes a client’s response time. However, since query size and distribution characteristics of data (data dense/sparse regions) in varying ranges are not known a priori, performing efficient load balancing and parallel processing over the unpredictable workload is difficult. A technique based on the creation and manipulation of dynamic spatial indexes for query payload estimation in distributed queries was proposed. The effectiveness of this technique was demonstrated on queries for analysis of archived earthquake-generated seismic data records.

  11. Adaptive Quantization Index Modulation Audio Watermarking based on Fuzzy Inference System

    Sunita V. Dhavale

    2014-02-01

    Full Text Available Many of the adaptive watermarking schemes reported in the literature consider only local audio signal properties. Many schemes require complex computation along with manual parameter settings. In this paper, we propose a novel, fuzzy, adaptive audio watermarking algorithm based on both global and local audio signal properties. The algorithm performs well for dynamic range of audio signals without requiring manual initial parameter selection. Here, mean value of energy (MVE and variance of spectral flux (VSF of a given audio signal constitutes global components, while the energy of each audio frame acts as local component. The Quantization Index Modulation (QIM step size Δ is made adaptive to both the global and local features. The global component automates the initial selection of Δ using the fuzzy inference system while the local component controls the variation in it based on the energy of individual audio frame. Hence Δ adaptively controls the strength of watermark to meet both the robustness and inaudibility requirements, making the system independent of audio nature. Experimental results reveal that our adaptive scheme outperforms other fixed step sized QIM schemes and adaptive schemes and is highly robust against general attacks.

  12. Spectral Efficiency Optimization for an Interfering Cognitive Radio with Adaptive Modulation and Coding

    Taki, Mehrdad

    2009-01-01

    In this paper, we consider a primary and a cognitive user transmitting over a wireless fading interference channel. The primary user transmits with a constant power and utilizes an adaptive modulation and coding (AMC) scheme satisfying a bit error rate requirement. We propose a link adaptation scheme to maximize the average spectral efficiency of the cognitive radio, while a minimum required spectral efficiency for the primary user is provisioned. The resulting problem is constrained to also satisfy a bit error rate requirement and a power constraint for the cognitive link. The AMC mode selection and power control at the cognitive transmitter is optimized based on the modified signal to noise plus interference ratio feedback of both links. The problem is then cast as a nonlinear discrete optimization problem for which a fast and efficient suboptimum solution is presented. We also present a scheme with rate adaptive and constant power cognitive radio. An important characteristic of the proposed schemes is that...

  13. Adaptive Modulation for DFIG and STATCOM With High-Voltage Direct Current Transmission.

    Tang, Yufei; He, Haibo; Ni, Zhen; Wen, Jinyu; Huang, Tingwen

    2016-08-01

    This paper develops an adaptive modulation approach for power system control based on the approximate/adaptive dynamic programming method, namely, the goal representation heuristic dynamic programming (GrHDP). In particular, we focus on the fault recovery problem of a doubly fed induction generator (DFIG)-based wind farm and a static synchronous compensator (STATCOM) with high-voltage direct current (HVDC) transmission. In this design, the online GrHDP-based controller provides three adaptive supplementary control signals to the DFIG controller, STATCOM controller, and HVDC rectifier controller, respectively. The mechanism is to observe the system states and their derivatives and then provides supplementary control to the plant according to the utility function. With the GrHDP design, the controller can adaptively develop an internal goal representation signal according to the observed power system states, therefore, to achieve more effective learning and modulating. Our control approach is validated on a wind power integrated benchmark system with two areas connected by HVDC transmission lines. Compared with the classical direct HDP and proportional integral control, our GrHDP approach demonstrates the improved transient stability under system faults. Moreover, experiments under different system operating conditions with signal transmission delays are also carried out to further verify the effectiveness and robustness of the proposed approach. PMID:26701900

  14. Design and Development of Hybrid Multilevel Inverter employing Dual Reference Modulation Technique for Fuel Cell Applications

    R. Seyezhai; Banuparvathy Kalpana

    2011-01-01

    MultiLevel Inverter (MLI) has been recognized as an attractive topology for high voltage DC-AC conversion. This paper focuses on a new dual reference modulation technique for a hybrid multilevel inverter employing Silicon carbide (SiC) switches for fuel cell applications. The proposed modulation technique employs two reference waveforms and a single inverted sine wave as the carrier waveform. This technique is compared with the conventional dual carrier waveform in terms of output voltage spe...

  15. Advanced Modulation Techniques for High-Performance Computing Optical Interconnects

    Karinou, Fotini; Borkowski, Robert; Zibar, Darko;

    2013-01-01

    optical shared memory supercomputer interconnect system switch fabric. In particular, we investigate the resilience of the aforementioned advanced modulation formats to the nonlinearities of semiconductor optical amplifiers, used as ON/OFF gates in the supercomputer optical switch fabric under study. In...

  16. Adaptive array technique for differential-phase reflectometry in QUEST

    Idei, H., E-mail: idei@triam.kyushu-u.ac.jp; Hanada, K.; Zushi, H. [Research Institute for Applied Mechanics, Kyushu Univ., Kasuga, 816-8560 Japan (Japan); Nagata, K.; Mishra, K.; Itado, T.; Akimoto, R. [Interdisciplinary Grad. School of Eng. Sci., Kyushu Univ., Kasuga, 816-8580 Japan (Japan); Yamamoto, M. K. [Research Institute for Sustainable Humanosphere, Kyoto Univ., Uji, 611-0011 Japan (Japan)

    2014-11-15

    A Phased Array Antenna (PAA) was considered as launching and receiving antennae in reflectometry to attain good directivity in its applied microwave range. A well-focused beam was obtained in a launching antenna application, and differential-phase evolution was properly measured by using a metal reflector plate in the proof-of-principle experiment at low power test facilities. Differential-phase evolution was also evaluated by using the PAA in the Q-shu University Experiment with Steady State Spherical Tokamak (QUEST). A beam-forming technique was applied in receiving phased-array antenna measurements. In the QUEST device that should be considered as a large oversized cavity, standing wave effect was significantly observed with perturbed phase evolution. A new approach using derivative of measured field on propagating wavenumber was proposed to eliminate the standing wave effect.

  17. ADAPTIVE LIFTING BASED IMAGE COMPRESSION SCHEME WITH PARTICLE SWARM OPTIMIZATION TECHNIQUE

    Nishat kanvel; Dr.S.Letitia,; Dr.Elwin Chandra Monie

    2010-01-01

    This paper presents an adaptive lifting scheme with Particle Swarm Optimization technique for image compression. Particle swarm Optimization technique is used to improve the accuracy of the predictionfunction used in the lifting scheme. This scheme is applied in Image compression and parameters such as PSNR, Compression Ratio and the visual quality of the image is calculated .The proposed scheme iscompared with the existing methods.

  18. FUMET: A fuzzy network module extraction technique for gene expression data

    Priyakshi Mahanta; Hasin Afzal Ahmed; Dhruba Kumar Bhattacharyya; Ashish Ghosh

    2014-06-01

    Construction of co-expression network and extraction of network modules have been an appealing area of bioinformatics research. This article presents a co-expression network construction and a biologically relevant network module extraction technique based on fuzzy set theoretic approach. The technique is able to handle both positive and negative correlations among genes. The constructed network for some benchmark gene expression datasets have been validated using topological internal and external measures. The effectiveness of network module extraction technique has been established in terms of well-known p-value, Q-value and topological statistics.

  19. An adaptive laser beam shaping technique based on a genetic algorithm

    Ping Yang; Yuan Liu; Wei Yang; Minwu Ao; Shijie Hu; Bing Xu; Wenhan Jiang

    2007-01-01

    @@ A new adaptive beam intensity shaping technique based on the combination of a 19-element piezo-electricity deformable mirror (DM) and a global genetic algorithm is presented. This technique can adaptively adjust the voltages of the 19 actuators on the DM to reduce the difference between the target beam shape and the actual beam shape. Numerical simulations and experimental results show that within the stroke range of the DM, this technique can be well used to create the given beam intensity profiles on the focal plane.

  20. Adaptive Input-Output Linearization Technique for Robust Speed Control of Brush less DC Motor

    Kim, Kyeong Hwa; Baik, In Cheol; Kim, Hyun Soo; Youn, Myung Joong [Korea Advance Institute of Science and Technology, Taejon (Korea, Republic of)

    1997-06-01

    An adaptive input-output linearization technique for a robust speed control of a brush less DC (BLDC) motor is presented. By using this technique, the nonlinear motor model can be effectively linearized in Brunovski canonical form, and the desired speed dynamics can be obtained based on the linearized model. This control technique, however, gives an undesirable output performance under the mismatch of the system parameters and load conditions caused by the incomplete linearization. For the robust output response, the controller parameters will be estimated by a model reference adaptive technique where the disturbance torque and flux linkage are estimated. The adaptation laws are derived by the Popov`s hyper stability theory and positivity concept. The proposed control scheme is implemented on a BLDC motor using the software of DSP TMS320C30 and the effectiveness is verified through the comparative simulations and experiments. (author). 14 refs., 12 figs., 1 tab.

  1. Modulation Technique Using Boundary-Pulse-Width for a Single-phase Power Inverter

    Igried Dib Al-Khawaldeh; O. Aloquili; J.A. Ghaeb

    2010-01-01

    The pulse-width-modulation technique plays a very important role in the inverter gain control. New varied-pulse width techniques for power inverters of two schemes have been introduced in this study: Small Boundary-Pulse-W idth Technique (SBPW), and Large Boundary-Pulse-Width technique (LBPW). These techniques are developed to improve the inverter operation, based on minimum harmonic contents in the output voltage. The original pulse-w idth of an inverter operation is divided into multiple pu...

  2. Intensity-modulated linear-frequency-modulated continuous-wave lidar for distributed media: fundamentals of technique.

    Batet, Oscar; Dios, Federico; Comeron, Adolfo; Agishev, Ravil

    2010-06-10

    We analyze the intensity-modulation frequency-modulated continuous-wave (FMCW) technique for lidar remote sensing in the context of its application to distributed media. The goal of the technique is the reproduction of the sounded-medium profile along the emission path. A conceptual analysis is carried out to show the problems the basic version of the method presents for this application. The principal point is the appearance of a bandpass filtering effect, which seems to hinder its use in this context. A modified version of the technique is proposed to overcome this problem. A number of computer simulations confirm the ability of the modified FMCW technique to sound distributed media. PMID:20539357

  3. Adaptive Remote-Sensing Techniques Implementing Swarms of Mobile Agents

    Asher, R.B.; Cameron, S.M.; Loubriel, G.M.; Robinett, R.D.; Stantz, K.M.; Trahan, M.W.; Wagner, J.S.

    1998-11-25

    In many situations, stand-off remote-sensing and hazard-interdiction techniques over realistic operational areas are often impractical "and difficult to characterize. An alternative approach is to implement an adap- tively deployable array of sensitive agent-specific devices. Our group has been studying the collective be- havior of an autonomous, multi-agent system applied to chedbio detection and related emerging threat applications, The current physics-based models we are using coordinate a sensor array for mukivanate sig- nal optimization and coverage as re,alized by a swarm of robots or mobile vehicles. These intelligent control systems integrate'glob"ally operating decision-making systems and locally cooperative learning neural net- works to enhance re+-timp operational responses to dynarnical environments examples of which include obstacle avoidance, res~onding to prevailing wind patterns, and overcoming other natural obscurants or in- terferences. Collectively',tkensor nefirons with simple properties, interacting according to basic community rules, can accomplish complex interconnecting functions such as generalization, error correction, pattern recognition, sensor fusion, and localization. Neural nets provide a greater degree of robusmess and fault tolerance than conventional systems in that minor variations or imperfections do not impair performance. The robotic platforms would be equipped with sensor devices that perform opticaI detection of biologicais in combination with multivariate chemical analysis tools based on genetic and neural network algorithms, laser-diode LIDAR analysis, ultra-wideband short-pulsed transmitting and receiving antennas, thermal im- a:ing sensors, and optical Communication technology providing robust data throughput pathways. Mission scenarios under consideration include ground penetrating radar (GPR) for detection of underground struc- tures, airborne systems, and plume migration and mitigation. We will describe our

  4. Image-based Position Estimation and Adaptive Modulation Coding in Vehicular Communication

    Hao Yang

    2011-12-01

    Full Text Available Vehicle position estimation is a key technology for Inter-Vehicle Communications, while template matching can be used to get information of vehicular position. In the paper, a simplified template matching, namely area-based template match is considered. A vehicular communication system designed for wireless data application is proposed where a camera is fixed in a vehicle which is served as a base station. By means of comparison between the outline area of vehicular image and reference templates, the base station can obtain the position estimation of the vehicle. The reference templates can be pre-calculated from a group of field experiment data. Based on supervised learning, we develop an image-based vehicle position estimation method and evaluate its effect on an adaptive coding modulation scheme. The computer simulation results show that in the wireless fading channel with the OFDM physical model, compared with fixed modulation coding scheme, the studied adaptive modulation and coding (AMC scheme taking account of the position estimation can gain greater throughput.

  5. PERFORMANCE ANALYSIS OF MIMO-SPACE TIME BLOCK CODING WITH DIFFERENT MODULATION TECHNIQUES

    Shubhangi Chaudhary

    2012-03-01

    Full Text Available MIMO Diversity is the technique which takes the advantage of multipath and mitigates the effect of fading and increases signal strength. Space Time Block code (STBC is used in Multiple Input Multiple Output (MIMO system to improve the performance by maximizing diversity gain. In this paper Math Works-SIMULINK platform is used for simulation. The performance of MIMO, Space Time Block Code (STBC with different modulations, such as M-ary Phase Shift Keying (M-PSK, Binary phase shift modulation (BPSK, Quadrature phase shift modulation (QPSK, 8-PSK, and M-ary Quadrature Amplitude Modulation (M-QAM, 16-Quadrature Amplitude modulation (16-QAM and 64-Quadrature Amplitude modulation (64QAM, 256-Quadrature Amplitude modulation (256-QAM are studied on the basis of bit error rate (BER, signal-to-noise ratio (SNR and error probability.

  6. (Costing) The adaption of product cost estimation techniques to estimate the cost of service.

    Huang, Estelle; Newnes, Linda B; Parry, Glenn

    2011-01-01

    Abstract This paper presents an approach to ascertain whether product cost estimating techniques can be adapted for use in estimating the costs for providing a service. The research methodology adopted consists of a critique and analysis of the literature to ascertain how current cost estimation techniques are used. The analysis of the cost estimation techniques provides knowledge of cost estimation, in particular for products and service with advantages and drawbacks defined. Th...

  7. Modulation technique for Four-Leg Voltage Source Inverter without a Look-Up Table

    Ebrahimzadeh, Esmaeil; Farhangi, Shahrokh; Iman-Eini, Hossein;

    2016-01-01

    adopted in all kinds of sequencing schemes. Unlike conventional techniques, the proposed technique needs no switching vector determination and duty ratio calculation as well as reduces the computational burden. In this technique, turn-on interval of the upper switches, in every switching period......Three-dimensional space-vector modulation (3D SVM) has more popularity among the other modulation techniques of the four-leg inverter due to higher DC-link voltage utilisation. Sequencing schemes of the switching vectors in the 3D SVM are divided into Class I and II categories. Each......, is calculated without need of a look-up table and complex equations. Applying the dead time by software is very straightforward in the proposed technique. In addition, by simplification of the proposed modulation technique, it can be applied to the three-leg inverters. Simulation results in PSCAD...

  8. Performance analysis of joint multi-branch switched diversity and adaptive modulation schemes for spectrum sharing systems

    Bouida, Zied

    2012-12-01

    Under the scenario of an underlay cognitive radio network, we propose in this paper two adaptive schemes using switched transmit diversity and adaptive modulation in order to increase the spectral efficiency of the secondary link and maintain a desired performance for the primary link. The proposed switching efficient scheme (SES) and bandwidth efficient scheme (BES) use the scan and wait combining technique (SWC) where a transmission occurs only when a branch with an acceptable performance is found, otherwise data is buffered. In these schemes, the modulation constellation size and the used transmit branch are determined to minimize the average number of switched branches and to achieve the highest spectral efficiency given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver (PR). For delay-sensitive applications, we also propose two variations of the SES and BES schemes using power control (SES-PC and BES-PC) where the secondary transmitter (ST) starts sending data using a nominal power level which is selected in order to minimize the average delay introduced by the SWC technique. We demonstrate through numerical examples that the BES scheme increases the capacity of the secondary link when compared to the SES scheme. This spectral efficiency improvement comes at the expense of an increased average number of switched branches and thus an increased average delay. We also show that the SES-PC and the BES-PC schemes minimize the average delay while satisfying the same spectral efficiency as the SES and BES schemes, respectively. © 2012 IEEE.

  9. Adaptive Pointing Design and Evaluation of a Precision Enhancing Technique for Absolute Pointing Devices

    König, Werner A.; Gerken, Jens; Dierdorf, Stefan; Reiterer, Harald

    2009-01-01

    We present Adaptive Pointing, a novel approach to addressing the common problem of accuracy when using absolute pointing devices for distant interaction. First, we discuss extensively some related work concerning the problem-domain of pointing accuracy when using absolute or relative pointing devices. As a result, we introduce a novel classification scheme to more clearly discriminate between different approaches. Second, the Adaptive Pointing technique is presented and described in detail. ...

  10. Adaptive Readout Technique For A Sixteen Channel Peak Sensing ADC In the FERA Format

    An adaptive, variable block-size readout technique for use with multiple, sixteen-channel CAMAC ADCs with a FERA-bus readout has been developed and designed. It can be used to read data from experiments with or without coincidence, i.e. singles, without having to change the readout protocol. Details of the implementation are discussed and initial results are presented. Further applications of the adaptive readout are also discussed

  11. Tangential volumetric modulated arc therapy technique for left-sided breast cancer radiotherapy

    Virén, Tuomas; Heikkilä, Janne; Myllyoja, Kimmo; Koskela, Kristiina; Lahtinen, Tapani; Seppälä, Jan

    2015-01-01

    Background The aim of the present study was to introduce a new restricted tangential volumetric modulated arc therapy (tVMAT) technique for whole breast irradiation and compare its dosimetric properties to other currently used breast cancer radiotherapy techniques. Method Ten consecutive women with left-sided breast cancer were enrolled in this retrospective study. Four treatment plans were generated for each patient: 1) standard tangential field-in-field (FinF), 2) tangential intensity modul...

  12. Joint Adaptive Modulation-Coding and Cooperative ARQ for Wireless Relay Networks

    Mardani, Morteza; Lahouti, Farshad; Eliasi, Behrouz

    2008-01-01

    This paper presents a cross-layer approach to jointly design adaptive modulation and coding (AMC) at the physical layer and cooperative truncated automatic repeat request (ARQ) protocol at the data link layer. We first derive an exact closed form expression for the spectral efficiency of the proposed joint AMC-cooperative ARQ scheme. Aiming at maximizing this system performance measure, we then optimize an AMC scheme which directly satisfies a prescribed packet loss rate constraint at the data-link layer. The results indicate that utilizing cooperative ARQ as a retransmission strategy, noticeably enhances the spectral efficiency compared with the system that employs AMC alone at the physical layer. Moreover, the proposed adaptive rate cooperative ARQ scheme outperforms the fixed rate counterpart when the transmission modes at the source and relay are chosen based on the channel statistics. This in turn quantifies the possible gain achieved by joint design of AMC and ARQ in wireless relay networks.

  13. CAPACITY BUILDING FOR CLIMATE CHANGE ADAPTATION: MODULES FOR AGRICULTURAL EXTENSION CURRICULUM DEVELOPMENT

    B.O. Ogunbameru

    2013-02-01

    Full Text Available Basically, climate change refers to any change in climate overtime, generally caused by natural variability and/or human activities. It has great devastating impact, particularly on agriculture and by extrapolation on farmers and the national economy. The frontline agricultural extension workers are expected to be among the principal stakeholders to teach farmers how to cope with climate change. Consequently, there is a need to develop appropriate teaching package for the training of the frontline agricultural extension workers, based on the myriad of adaptation strategies and practices available in the literature. This paper synthesizes the rationale for capacity building in climate change and the adaptation or coping strategies. The modules (train-the-trainer for teaching agricultural extension workers and farmers are documented in the paper.

  14. CRISPR/Cas and Cmr modules, mobility and evolution of adaptive immune systems

    Shah, Shiraz Ali; Garrett, Roger Antony

    2011-01-01

    CRISPR/Cas and CRISPR/Cmr immune machineries of archaea and bacteria provide an adaptive and effective defence mechanism directed specifically against viruses and plasmids. Present data suggest that both CRISPR/Cas and Cmr modules can behave like integral genetic elements. They tend to be located...... in the more variable regions of chromosomes and are displaced by genome shuffling mechanisms including transposition. CRISPR loci may be broken up and dispersed in chromosomes by transposons with the potential for creating genetic novelty. Both CRISPR/Cas and Cmr modules appear to exchange readily...... the significant barriers imposed by their differing conjugative, transcriptional and translational mechanisms. There are parallels between the CRISPR crRNAs and eukaryal siRNAs, most notably to germ cell piRNAs which are directed, with the help of effector proteins, to silence or destroy transposons...

  15. Evaluation of an adaptive filtering algorithm for CT cardiac imaging with EKG modulated tube current

    Li, Jianying; Hsieh, Jiang; Mohr, Kelly; Okerlund, Darin

    2005-04-01

    We have developed an adaptive filtering algorithm for cardiac CT scans with EKG-modulated tube current to optimize resolution and noise for different cardiac phases and to provide safety net for cases where end-systole phase is used for coronary imaging. This algorithm has been evaluated using patient cardiac CT scans where lower tube currents are used for the systolic phases. In this paper, we present the evaluation results. The results demonstrated that with the use of the proposed algorithm, we could improve image quality for all cardiac phases, while providing greater noise and streak artifact reduction for systole phases where lower CT dose were used.

  16. Development and verification of unstructured adaptive mesh technique with edge compatibility

    In the design study of the large-sized sodium-cooled fast reactor (JSFR), one key issue is suppression of gas entrainment (GE) phenomena at a gas-liquid interface. Therefore, the authors have been developed a high-precision CFD algorithm to evaluate the GE phenomena accurately. The CFD algorithm has been developed on unstructured meshes to establish an accurate modeling of JSFR system. For two-phase interfacial flow simulations, a high-precision volume-of-fluid algorithm is employed. It was confirmed that the developed CFD algorithm could reproduce the GE phenomena in a simple GE experiment. Recently, the authors have been developed an important technique for the simulation of the GE phenomena in JSFR. That is an unstructured adaptive mesh technique which can apply fine cells dynamically to the region where the GE occurs in JSFR. In this paper, as a part of the development, a two-dimensional unstructured adaptive mesh technique is discussed. In the two-dimensional adaptive mesh technique, each cell is refined isotropically to reduce distortions of the mesh. In addition, connection cells are formed to eliminate the edge incompatibility between refined and non-refined cells. The two-dimensional unstructured adaptive mesh technique is verified by solving well-known lid-driven cavity flow problem. As a result, the two-dimensional unstructured adaptive mesh technique succeeds in providing a high-precision solution, even though poor-quality distorted initial mesh is employed. In addition, the simulation error on the two-dimensional unstructured adaptive mesh is much less than the error on the structured mesh with a larger number of cells. (author)

  17. Neural and fuzzy computation techniques for playout delay adaptation in VoIP networks.

    Ranganathan, Mohan Krishna; Kilmartin, Liam

    2005-09-01

    Playout delay adaptation algorithms are often used in real time voice communication over packet-switched networks to counteract the effects of network jitter at the receiver. Whilst the conventional algorithms developed for silence-suppressed speech transmission focused on preserving the relative temporal structure of speech frames/packets within a talkspurt (intertalkspurt adaptation), more recently developed algorithms strive to achieve better quality by allowing for playout delay adaptation within a talkspurt (intratalkspurt adaptation). The adaptation algorithms, both intertalkspurt and intratalkspurt based, rely on short term estimations of the characteristics of network delay that would be experienced by up-coming voice packets. The use of novel neural networks and fuzzy systems as estimators of network delay characteristics are presented in this paper. Their performance is analyzed in comparison with a number of traditional techniques for both inter and intratalkspurt adaptation paradigms. The design of a novel fuzzy trend analyzer system (FTAS) for network delay trend analysis and its usage in intratalkspurt playout delay adaptation are presented in greater detail. The performance of the proposed mechanism is analyzed based on measured Internet delays. Index Terms-Fuzzy delay trend analysis, intertalkspurt, intratalkspurt, multilayer perceptrons (MLPs), network delay estimation, playout buffering, playout delay adaptation, time delay neural networks (TDNNs), voice over Internet protocol (VoIP). PMID:16252825

  18. A Processing Technique for OFDM-Modulated Wideband Radar Signals

    Tigrek, R.F.

    2010-01-01

    The orthogonal frequency division multiplexing (OFDM) is a multicarrier spread-spectrum technique which finds wide-spread use in communications. The OFDM pulse compression method that utilizes an OFDM communication signal for radar tasks has been developed and reported in this dissertation. Using th

  19. An efficient Video Segmentation Algorithm with Real time Adaptive Threshold Technique

    Yasira Beevi C P

    2009-12-01

    Full Text Available Automatic video segmentation plays an important role in real-time MPEG-4 encoding systems. This paper presents a video segmentation algorithm for MPEG-4 camera system with change detection, background registration techniques and real time adaptive thresholdtechniques. This algorithm can give satisfying segmentation results with low computation load. Besides, it has shadow cancellation mode, which can deal with light changing effect and shadow effect. Furthermore, this algorithm also implemented real time adaptive threshold techniques by which the parameters can be decided automatically.

  20. Optimal control techniques for the adaptive optics system of the LBT

    Agapito, G.; Quiros-Pacheco, F.; Tesi, P.; Esposito, S.; Xompero, M.

    2008-07-01

    In this paper we will discuss the application of different optimal control techniques for the adaptive optics system of the LBT telescope which comprises a pyramid wavefront sensor and an adaptive secondary mirror. We have studied the application of both the Kalman and the H∞ filter to estimate the temporal evolution of the phase perturbations due to the atmospheric turbulence and the telescope vibrations. We have evaluated the performance of these control techniques with numerical simulations in preparation of the laboratory tests that will be carried out in the Arcetri laboratories.

  1. Constrained Optimization Based on Hybrid Evolutionary Algorithm and Adaptive Constraint-Handling Technique

    Wang, Yong; Cai, Zixing; Zhou, Yuren; Fan, Zhun

    2009-01-01

    A novel approach to deal with numerical and engineering constrained optimization problems, which incorporates a hybrid evolutionary algorithm and an adaptive constraint-handling technique, is presented in this paper. The hybrid evolutionary algorithm simultaneously uses simplex crossover and two...... four well-known constrained design problems verify the effectiveness and efficiency of the proposed method. The experimental results show that integrating the hybrid evolutionary algorithm with the adaptive constraint-handling technique is beneficial, and the proposed method achieves competitive...... performance with respect to some other state-of-the-art approaches in constrained evolutionary optimization....

  2. Modified Dual Three-Pulse Modulation technique for single-phase inverter topology

    Sree Harsha, N. R.; Anitha, G. S.; Sreedevi, A.

    2016-01-01

    In a recent paper, a new modulation technique called Dual Three Pulse Modulation (DTPM) was proposed to improve the efficiency of the power converters of the Electric/Hybrid/Fuel-cell vehicles. It was simulated in PSIM 9.0.4 and uses analog multiplexers to generate the modulating signals for the DC/DC converter and inverter. The circuit used is complex and many other simulation softwares do not support the analog multiplexers as well. Also, the DTPM technique produces modulating signals for the converter, which are essentially needed to produce the modulating signals for the inverter. Hence, it cannot be used efficiently to switch the valves of a stand-alone inverter. We propose a new method to generate the modulating signals to switch MOSFETs of a single phase Dual-Three pulse Modulation based stand-alone inverter. The circuits proposed are simulated in Multisim 12.0. We also show an alternate way to switch a DC/DC converter in a way depicted by DTPM technique both in simulation (MATLAB/Simulink) and hardware. The circuitry is relatively simple and can be used for the further investigations of DTPM technique.

  3. Development of the power modulation technique in JT-60U ECH system

    Millimeter waves at 110 GHz of the electron cyclotron heating (ECH) system are sometimes injected to JT-60U plasmas with pulse modulation at dozens to hundreds of Hz in order to measure heat conductivity of the plasma to investigate plasma confinement. The JT-60U ECH system has a unique feature to realize the pulse modulation by controlling the anode voltage of the triode gyrotron without chopping the main acceleration voltage. The typical depth of the modulation is 80% at the modulation frequency range of 12.2 Hz to 500 Hz. However in the JT-60 super advanced (SA) project, higher modulation frequency of some kHz will be required to stabilize neoclassical tearing mode (NTM) as a magneto hydro dynamic (MHD) instability. The modulation techniques have been investigated and the modulation frequency of 3.5 kHz with the modulation depth of 84% has been achieved. The modulation frequency up to 3 kHz is available in the pulse widths of the practical operation. As a next step, replacement of the parts in the anode voltage divider circuit is planned to achieve higher modulation frequency. (author)

  4. A SELF-ADAPTIVE TECHNIQUE FOR A KIND OF NONLINEAR CONJUGATE GRADIENT METHODS

    王丽平

    2004-01-01

    Conjugate gradient methods. are a class of important methods for unconstrained optimization, especially when the dimension is large. In 2001, Dai and Liao have proposed a new conjugate condition, based on it two nonlinear conjugate gradient methods are constructed. With trust region idea, this paper gives a self-adaptive technique for the two methods. The numerical results show that this technique works well for the given nonlinear optimization test problems.

  5. An Approach for Automatic Generation of Adaptive Hypermedia in Education with Multilingual Knowledge Discovery Techniques

    Alfonseca, Enrique; Rodriguez, Pilar; Perez, Diana

    2007-01-01

    This work describes a framework that combines techniques from Adaptive Hypermedia and Natural Language processing in order to create, in a fully automated way, on-line information systems from linear texts in electronic format, such as textbooks. The process is divided into two steps: an "off-line" processing step, which analyses the source text,…

  6. Adaptations in physiology and propulsion techniques during the initial phase of learning manual wheelchair propulsion

    de Groot, S; Veeger, H E J; Hollander, A P; van der Woude, L H V

    2003-01-01

    OBJECTIVE: The purpose of this study was to analyze adaptations in gross mechanical efficiency and wheelchair propulsion technique in novice able-bodied subjects during the initial phase of learning hand-rim wheelchair propulsion. DESIGN: Nine able-bodied subjects performed three 4-min practice bloc

  7. Mental fatigue modulates dynamic adaptation to perceptual demand in speeded detection.

    Robert Langner

    Full Text Available When stimulus intensity in simple reaction-time tasks randomly varies across trials, detection speed usually improves after a low-intensity trial. With auditory stimuli, this improvement was often found to be asymmetric, being greater on current low-intensity trials. Our study investigated (1 whether asymmetric sequential intensity adaptation also occurs with visual stimuli; (2 whether these adjustments reflect decision-criterion shifts or, rather, a modulation of perceptual sensitivity; and (3 how sequential intensity adaptation and its underlying mechanisms are affected by mental fatigue induced through prolonged performance. In a continuous speeded detection task with randomly alternating high- and low-intensity visual stimuli, the reaction-time benefit after low-intensity trials was greater on subsequent low- than high-intensity trials. This asymmetry, however, only developed with time on task (TOT. Signal-detection analyses showed that the decision criterion transiently became more liberal after a low-intensity trial, whereas observer sensitivity increased when the preceding and current stimulus were of equal intensity. TOT-induced mental fatigue only affected sensitivity, which dropped more on low- than on high-intensity trials. This differential fatigue-related sensitivity decrease selectively enhanced the impact of criterion down-shifts on low-intensity trials, revealing how the interplay of two perceptual mechanisms and their modulation by fatigue combine to produce the observed overall pattern of asymmetric performance adjustments to varying visual intensity in continuous speeded detection. Our results have implications for similar patterns of sequential demand adaptation in other cognitive domains as well as for real-world prolonged detection performance.

  8. Cultural adaptation and validation of the Freiburg Life Quality Assessment - Wound Module to Brazilian Portuguese

    Elaine Aparecida Rocha Domingues

    2016-01-01

    Full Text Available Objectives: to adapt the Freiburg Life Quality Assessment - Wound Module to Brazilian Portuguese and to measure its psychometric properties: reliability and validity. Method: the cultural adaptation was undertaken following the stages of translation, synthesis of the translations, back translation, committee of specialists, pre-test and focus group. A total of 200 patients participated in the study. These were recruited in Primary Care Centers, Family Health Strategy Centers, in a philanthropic hospital and in a teaching hospital. Reliability was assessed through internal consistency and stability. Validity was ascertained through the correlation of the instrument's values with those of the domains of the Ferrans and Powers Quality of Life Index - Wound Version and with the quality of life score of the visual analog scale. Results: the instrument presented adequate internal consistency (Cronbach alpha =0.86 and high stability in the test and retest (0.93. The validity presented correlations of moderate and significant magnitude (-0.24 to -0.48, p<0.0001. Conclusion: the results indicated that the adapted version presented reliable and valid psychometric measurements for the population with chronic wounds in the Brazilian culture.

  9. Cultural adaptation and validation of the Freiburg Life Quality Assessment - Wound Module to Brazilian Portuguese1

    Domingues, Elaine Aparecida Rocha; Alexandre, Neusa Maria Costa; da Silva, José Vitor

    2016-01-01

    Objectives: to adapt the Freiburg Life Quality Assessment - Wound Module to Brazilian Portuguese and to measure its psychometric properties: reliability and validity. Method: the cultural adaptation was undertaken following the stages of translation, synthesis of the translations, back translation, committee of specialists, pre-test and focus group. A total of 200 patients participated in the study. These were recruited in Primary Care Centers, Family Health Strategy Centers, in a philanthropic hospital and in a teaching hospital. Reliability was assessed through internal consistency and stability. Validity was ascertained through the correlation of the instrument's values with those of the domains of the Ferrans and Powers Quality of Life Index - Wound Version and with the quality of life score of the visual analog scale. Results: the instrument presented adequate internal consistency (Cronbach alpha =0.86) and high stability in the test and retest (0.93). The validity presented correlations of moderate and significant magnitude (-0.24 to -0.48, p<0.0001). Conclusion: the results indicated that the adapted version presented reliable and valid psychometric measurements for the population with chronic wounds in the Brazilian culture. PMID:27143539

  10. Privacy-Preserving Data Analysis Techniques by using different modules

    Payal P. Wasankar

    2013-11-01

    Full Text Available The competing parties who have private data may collaboratively conduct privacy preserving distributed data analysis (PPDA tasks to learn beneficial data models or analysis results. For example, different credit card companies may try to build better models for credit card fraud detection through PPDA tasks. Similarly, competing companies in the same industry may try to combine their sales data to build models that may predict the future sales. In many of these cases, the competing parties have different incentives. Although certain PPDA techniques guarantee that nothing other than the final analysis result is revealed, it is impossible to verify whether or not participating parties are truthful about their private input data.

  11. Range modulation in proton therapy - an optimization technique for clinical and experimental applications

    A fast optimization algorithm for range modulation in clinical and experimental applications of proton therapy is described. The method is versatile towards the number of parameters provided for range modulation, i.e. the trade-off between accuracy and simplicity of the latter can be chosen freely. The approach is, therefore, adaptable to most operating proton therapy facilities. It requires only a few basic measurements as input data and results in a depth dose uniformity of better than 2%. A typical calculation takes less than 90 s on a DEC VAXstation 3100, FORTRAN. The method has been extensively tested at the TRIUMF Proton Therapy Facility in Vancouver, BC. (author)

  12. Three-dimensional region-based adaptive image processing techniques for volume visualization applications

    de Deus Lopes, Roseli; Zuffo, Marcelo K.; Rangayyan, Rangaraj M.

    1996-04-01

    Recent advances in three-dimensional (3D) imaging techniques have expanded the scope of applications of volume visualization to many areas such as medical imaging, scientific visualization, robotic vision, and virtual reality. Advanced image filtering, enhancement, and analysis techniques are being developed in parallel in the field of digital image processing. Although the fields cited have many aspects in common, it appears that many of the latest developments in image processing are not being applied to the fullest extent possible in visualization. It is common to encounter the use of rather simple and elementary image pre- processing operations being used in visualization and 3D imaging applications. The purpose of this paper is to present an overview of selected topics from recent developments in adaptive image processing and demonstrate or suggest their applications in volume visualization. The techniques include adaptive noise removal; improvement of contrast and visibility of objects; space-variant deblurring and restoration; segmentation-based lossless coding for data compression; and perception-based measures for analysis, enhancement, and rendering. The techniques share the common base of identification of adaptive regions by region growing, which lends them a perceptual basis related to the human visual system. Preliminary results obtained with some of the techniques implemented so far are used to illustrate the concepts involved, and to indicate potential performance capabilities of the methods.

  13. Adaptive illumination through spatial modulation of light intensity and image inversion

    The paper introduces the concept of spatial modulation of light intensity in the context of vision-based quality control, with the aim to improve image quality, measurable by indices such as image contrast and Tenengrad, so as to enhance the level of confidence of the diagnosis performed by image processing. The proposed technique is based on the projection of spatially modulated light intensity distribution by a digital light projector that allows an arbitrary light distribution to be projected on the target. The projected spatial distribution of light is determined by implementing an algorithm based on image inversion: the image acquired by the camera under uniform illumination is inverted and it is then used to modulate the light spatial distribution for projection. The process is repeated iteratively with the purpose to enhance image quality until convergence. The technique proves particularly valuable to avoid saturation from reflecting surfaces, which are often found in industrial practice. The procedure is tested and validated both by a numerical model and by an experimental validation, referring to a significant problem for the washing machine manufacturing industry. The use of image quality estimators confirms the effectiveness of the method. (paper)

  14. A high-resolution displacement sensor based on a grating interferometer with the phase modulation technique

    A high-resolution displacement sensor based on a grating interferometer with the phase modulation technique is demonstrated in this paper. The grating interferometer is formed with a grating and a mirror, which is fixed on a piezoelectric translator to generate phase modulation. The detected signal is intensity-modulated and processed with a lock-in amplifier for demodulation. Experimental results show that this displacement sensor has a displacement sensitivity of 19.8 mV nm−1 and a high-resolution displacement detection of 0.05 nm in the linear region. (paper)

  15. An Adaptive Technique for a Redundant-Sensor Navigation System. Ph.D. Thesis

    Chien, T. T.

    1972-01-01

    An on-line adaptive technique is developed to provide a self-contained redundant-sensor navigation system with a capability to utilize its full potentiality in reliability and performance. The gyro navigation system is modeled as a Gauss-Markov process, with degradation modes defined as changes in characteristics specified by parameters associated with the model. The adaptive system is formulated as a multistage stochastic process: (1) a detection system, (2) an identification system and (3) a compensation system. It is shown that the sufficient statistics for the partially observable process in the detection and identification system is the posterior measure of the state of degradation, conditioned on the measurement history.

  16. Multi-Level Adaptive Techniques (MLAT) for singular-perturbation problems

    Brandt, A.

    1978-01-01

    The multilevel (multigrid) adaptive technique, a general strategy of solving continuous problems by cycling between coarser and finer levels of discretization is described. It provides very fast general solvers, together with adaptive, nearly optimal discretization schemes. In the process, boundary layers are automatically either resolved or skipped, depending on a control function which expresses the computational goal. The global error decreases exponentially as a function of the overall computational work, in a uniform rate independent of the magnitude of the singular-perturbation terms. The key is high-order uniformly stable difference equations, and uniformly smoothing relaxation schemes.

  17. Jitter model and signal processing techniques for pulse width modulation optical recording

    Liu, Max M.-K.

    1991-01-01

    A jitter model and signal processing techniques are discussed for data recovery in Pulse Width Modulation (PWM) optical recording. In PWM, information is stored through modulating sizes of sequential marks alternating in magnetic polarization or in material structure. Jitter, defined as the deviation from the original mark size in the time domain, will result in error detection if it is excessively large. A new approach is taken in data recovery by first using a high speed counter clock to convert time marks to amplitude marks, and signal processing techniques are used to minimize jitter according to the jitter model. The signal processing techniques include motor speed and intersymbol interference equalization, differential and additive detection, and differential and additive modulation.

  18. Comparison of Modulation Techniques for Underwater Optical Wireless Communication Employing APD Receivers

    Mazin Ali A. Ali

    2015-06-01

    Full Text Available In this study, we theoretically analyze the performance of an underwater optical wireless communications system using different modulation techniques and an avalanche photodiode APD receiver over underwater environment channels. Based on the LOS geometrical model and combined with signal to noise ratio model for Si and Ge APD and BER; then the impact of the distance of transmission and power of the transmitter and Jerlov water type are analyzed. The characteristics of bit error rate BER for different optical modulation techniques are studied. Simulation results indicate that the performance of H-QAM is more suited for an underwater optical wireless communication. On the other hand, the suitability of avalanche photodiodes under these modulation techniques is discussed, because the photodiode Si APD has more advantages compared with Ge APD when used in an underwater optical communication.

  19. WE-G-BRF-01: Adaptation to Intrafraction Tumor Deformation During Intensity-Modulated Radiotherapy: First Proof-Of-Principle Demonstration

    Purpose: Intrafraction tumor deformation limits targeting accuracy in radiotherapy and cannot be adapted to by current motion management techniques. This study simulated intrafractional treatment adaptation to tumor deformations using a dynamic Multi-Leaf Collimator (DMLC) tracking system during Intensity-modulated radiation therapy (IMRT) treatment for the first time. Methods: The DMLC tracking system was developed to adapt to the intrafraction tumor deformation by warping the planned beam aperture guided by the calculated deformation vector field (DVF) obtained from deformable image registration (DIR) at the time of treatment delivery. Seven single phantom deformation images up to 10.4 mm deformation and eight tumor system phantom deformation images up to 21.5 mm deformation were acquired and used in tracking simulation. The intrafraction adaptation was simulated at the DMLC tracking software platform, which was able to communicate with the image registration software, reshape the instantaneous IMRT field aperture and log the delivered MLC fields.The deformation adaptation accuracy was evaluated by a geometric target coverage metric defined as the sum of the area incorrectly outside and inside the reference aperture. The incremental deformations were arbitrarily determined to take place equally over the delivery interval. The geometric target coverage of delivery with deformation adaptation was compared against the delivery without adaptation. Results: Intrafraction deformation adaptation during dynamic IMRT plan delivery was simulated for single and system deformable phantoms. For the two particular delivery situations, over the treatment course, deformation adaptation improved the target coverage by 89% for single target deformation and 79% for tumor system deformation compared with no-tracking delivery. Conclusion: This work demonstrated the principle of real-time tumor deformation tracking using a DMLC. This is the first step towards the development of an

  20. WE-G-BRF-01: Adaptation to Intrafraction Tumor Deformation During Intensity-Modulated Radiotherapy: First Proof-Of-Principle Demonstration

    Ge, Y; OBrien, R; Shieh, C; Booth, J; Keall, P [Radiation Physics Laboratory, University of Sydney (Australia)

    2014-06-15

    Purpose: Intrafraction tumor deformation limits targeting accuracy in radiotherapy and cannot be adapted to by current motion management techniques. This study simulated intrafractional treatment adaptation to tumor deformations using a dynamic Multi-Leaf Collimator (DMLC) tracking system during Intensity-modulated radiation therapy (IMRT) treatment for the first time. Methods: The DMLC tracking system was developed to adapt to the intrafraction tumor deformation by warping the planned beam aperture guided by the calculated deformation vector field (DVF) obtained from deformable image registration (DIR) at the time of treatment delivery. Seven single phantom deformation images up to 10.4 mm deformation and eight tumor system phantom deformation images up to 21.5 mm deformation were acquired and used in tracking simulation. The intrafraction adaptation was simulated at the DMLC tracking software platform, which was able to communicate with the image registration software, reshape the instantaneous IMRT field aperture and log the delivered MLC fields.The deformation adaptation accuracy was evaluated by a geometric target coverage metric defined as the sum of the area incorrectly outside and inside the reference aperture. The incremental deformations were arbitrarily determined to take place equally over the delivery interval. The geometric target coverage of delivery with deformation adaptation was compared against the delivery without adaptation. Results: Intrafraction deformation adaptation during dynamic IMRT plan delivery was simulated for single and system deformable phantoms. For the two particular delivery situations, over the treatment course, deformation adaptation improved the target coverage by 89% for single target deformation and 79% for tumor system deformation compared with no-tracking delivery. Conclusion: This work demonstrated the principle of real-time tumor deformation tracking using a DMLC. This is the first step towards the development of an

  1. Performance analysis of two-way amplify and forward relaying with adaptive modulation

    Hwang, Kyusung

    2009-09-01

    In this paper, we study two-way amplify-and-forward relaying in conjunction with adaptive modulation over a multiple relay network. In order to keep the diversity order equal to the number of relays and maintain a low complexity, we consider the best relay selection scheme in this work. Based on the proposed selection criterion for the best relay, we analyze the average spectral efficiency by its approximated upper bound. In addition, we extend the proposed scheme to the case where a direct path between source and destination exists. Our numerical examples show that the proposed system offers a considerable gain in the spectral efficiency while satisfying the error rates requirements. ©2009 IEEE.

  2. PERFORMANCE EVALUATION OF ADAPTIVE LDPC CODED MODULATION COOPERATIVE WIRELESS COMMUNICATION SYSTEM WITH BEST-RELAY SELECTION

    Ahmed S. Mohamed

    2014-03-01

    Full Text Available In this paper the performance of a cooperative wireless communication system based on combined best relay selection (BRS and adaptive LDPC coded modulation (ACM scheme is investigated. These investigations are focused on evaluating the performance of the proposed cooperative wireless communication system over independent non-identical Rayleigh fading channels in terms of bit-error rate (BER using MATLAB® computer simulations and comparing the system performance with ACM direct transmission and ACM cooperative with single relay. The simulations results show that the proposed cooperative scheme achieves lower signal-to-noise ratio (SNR values for desired bit-error rate (BER and high spectral efficiency as compared to ACM direct transmission and ACM cooperative with single relay.

  3. Adaptive electron beam shaping using a photoemission gun and spatial light modulator

    Maxson, Jared; Lee, Hyeri; Bartnik, Adam C.; Kiefer, Jacob; Bazarov, Ivan

    2015-02-01

    The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam image to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.

  4. Capacity achieving nonbinary LDPC coded non-uniform shaping modulation for adaptive optical communications.

    Lin, Changyu; Zou, Ding; Liu, Tao; Djordjevic, Ivan B

    2016-08-01

    A mutual information inspired nonbinary coded modulation design with non-uniform shaping is proposed. Instead of traditional power of two signal constellation sizes, we design 5-QAM, 7-QAM and 9-QAM constellations, which can be used in adaptive optical networks. The non-uniform shaping and LDPC code rate are jointly considered in the design, which results in a better performance scheme for the same SNR values. The matched nonbinary (NB) LDPC code is used for this scheme, which further improves the coding gain and the overall performance. We analyze both coding performance and system SNR performance. We show that the proposed NB LDPC-coded 9-QAM has more than 2dB gain in symbol SNR compared to traditional LDPC-coded star-8-QAM. On the other hand, the proposed NB LDPC-coded 5-QAM and 7-QAM have even better performance than LDPC-coded QPSK. PMID:27505775

  5. A Novel Analog-to-digital conversion Technique using nonlinear duty-cycle modulation

    Jean Mbihi

    2012-06-01

    Full Text Available A new type of analog-to-digital conversion technique is presented in this paper. The interfacing hardware is a very simple nonlinear circuit with 1-bit modulated output. As a implication, behind the hardware simplicity retained is hidden a dreadful nonlinear duty-cycle modulation ratio. However, the overall nonlinear behavior embeds a sufficiently wide linear range, for a rigorous digital reconstitution of the analog input signal using a standard linear filter. Simulation and experimental results obtained using a well tested prototyping system, show the feasibility and good quality of the proposed conversion technique.

  6. Adaptive neuro-fuzzy prediction of modulation transfer function of optical lens system

    Petković, Dalibor; Shamshirband, Shahaboddin; Anuar, Nor Badrul; Md Nasir, Mohd Hairul Nizam; Pavlović, Nenad T.; Akib, Shatirah

    2014-07-01

    The quantitative assessment of image quality is an important consideration in any type of imaging system. The modulation transfer function (MTF) is a graphical description of the sharpness and contrast of an imaging system or of its individual components. The MTF is also known and spatial frequency response. The MTF curve has different meanings according to the corresponding frequency. The MTF of an optical system specifies the contrast transmitted by the system as a function of image size, and is determined by the inherent optical properties of the system. In this study, the adaptive neuro-fuzzy (ANFIS) estimator is designed and adapted to predict MTF value of the actual optical system. Neural network in ANFIS adjusts parameters of membership function in the fuzzy logic of the fuzzy inference system. The back propagation learning algorithm is used for training this network. This intelligent estimator is implemented using MATLAB/Simulink and the performances are investigated. The simulation results presented in this paper show the effectiveness of the developed method.

  7. Modulation transfer function estimation of optical lens system by adaptive neuro-fuzzy methodology

    Petković, Dalibor; Shamshirband, Shahaboddin; Pavlović, Nenad T.; Anuar, Nor Badrul; Kiah, Miss Laiha Mat

    2014-07-01

    The quantitative assessment of image quality is an important consideration in any type of imaging system. The modulation transfer function (MTF) is a graphical description of the sharpness and contrast of an imaging system or of its individual components. The MTF is also known and spatial frequency response. The MTF curve has different meanings according to the corresponding frequency. The MTF of an optical system specifies the contrast transmitted by the system as a function of image size, and is determined by the inherent optical properties of the system. In this study, the adaptive neuro-fuzzy (ANFIS) estimator is designed and adapted to estimate MTF value of the actual optical system. Neural network in ANFIS adjusts parameters of membership function in the fuzzy logic of the fuzzy inference system. The back propagation learning algorithm is used for training this network. This intelligent estimator is implemented using Matlab/Simulink and the performances are investigated. The simulation results presented in this paper show the effectiveness of the developed method.

  8. Cross-layer combining of adaptive modulation and truncated ARQ under cognitive radio resource requirements

    Yang, Yuli

    2012-11-01

    In addressing the issue of taking full advantage of the shared spectrum under imposed limitations in a cognitive radio (CR) network, we exploit a cross-layer design for the communications of secondary users (SUs), which combines adaptive modulation and coding (AMC) at the physical layer with truncated automatic repeat request (ARQ) protocol at the data link layer. To achieve high spectral efficiency (SE) while maintaining a target packet loss probability (PLP), switching among different transmission modes is performed to match the time-varying propagation conditions pertaining to the secondary link. Herein, by minimizing the SU\\'s packet error rate (PER) with each transmission mode subject to the spectrum-sharing constraints, we obtain the optimal power allocation at the secondary transmitter (ST) and then derive the probability density function (pdf) of the received SNR at the secondary receiver (SR). Based on these statistics, the SU\\'s packet loss rate and average SE are obtained in closed form, considering transmissions over block-fading channels with different distributions. Our results quantify the relation between the performance of a secondary link exploiting the cross-layer-designed adaptive transmission and the interference inflicted on the primary user (PU) in CR networks. © 1967-2012 IEEE.

  9. PWM Technique of Five-Leg Inverter Applying Two-Arm Modulation

    Oka, Kazuo; Matsuse, Kouki

    This paper presents the simple pulse width modulation (PWM) technique of a five-leg inverter to drive two three-phase AC motors independently. Normal PWM techniques in three-phase voltage source inverter cannot be used for the five-leg inverter with the independent drive. In this paper, two kinds of simple and novel PWM techniques of the five-leg inverter with two three-phase AC motors are introduced. Experimental results are provided to illustrate the validity of the proposed PWM technique.

  10. Comparison of Modulation Techniques for Multilevel Inverter fed Permanent Magnet Synchronous Motor

    V. NAGA BHASKAR REDDY

    2010-10-01

    Full Text Available Multilevel inversion is a power conversion strategy in which the output voltage is obtained in steps thus bringing the output closer to a sine wave and reduces the Total Harmonic Distortion. Multilevel inverter structures have been developed to overcome shortcomings in solid-state switching device ratings so that they can be applied to higher voltage systems. In recent years, the multilevel inverters have drawn tremendous interest in the area of high-power medium-voltage energy control. Three different topologies have been proposed for multilevel inverters like Diode-Clamped Inverter, Capacitor Clamped Inverter and Cascaded Multi cell Inverter. In addition, several modulation and control strategies have been developed or adopted for multilevel inverters including the following multilevel Sinusoidal Pulse Width Modulation (SPWM, and Space Vector Modulation. In this paper, simulation of various modulating techniques i.e., Pulse Width Modulate techniques such as Sinusoidal PWM, Trapezoidal PWM, Stepped PWM, Stair case PWM, third harmonicinjected PWM, Modified SVPWM are applied for both Diode Clamped Three-Level Inverter and Diode Clamped Five-Level Inverter, and Space Vector PWM technique are analyzed for DC3LI. The best modulationtechnique are extended to Permanent Magnet Synchronous Motor.

  11. Micro combined heat and power home supply: Prospective and adaptive management achieved by computational intelligence techniques

    Matics, Jens; Krost, Gerhard [University of Duisburg-Essen, Bismarckstrasse 81, D-47057 Duisburg (Germany)

    2008-11-15

    Micro combined heat and power (CHP) systems for single residential buildings are seen as advantageous to combine both decentralized power supply and rather high overall efficiency. The latter presupposes flexible and adaptive plant management which has to mediate between energy cost minimization and user comfort aspects. This is achieved by use of computational intelligence (CI) techniques; structure and performance of the management system are shown. (author)

  12. Observer-Based Control Techniques for the LBT Adaptive Optics under Telescope Vibrations

    Agapito, Guido; Quirós-Pacheco, Fernando; Tesi, Pietro; Riccardi, Armando; Esposito, Simone

    2011-01-01

    This paper addresses the application of observer-based control techniques for the adaptive optics system of the LBT telescope. In such a context, attention is focused on the use of Kalman and H∞ filters to estimate the temporal evolution of phase perturbations due to the atmospheric turbulence and the telescope vibrations acting on tip/tilt modes. We shall present preliminary laboratory experiments carried out at the Osservatorio Astrofisico di Arcetri using the Kalman filter.

  13. An Adaptive Image Enhancement Technique by Combining Cuckoo Search and Particle Swarm Optimization Algorithm

    Zhiwei Ye; Mingwei Wang; Zhengbing Hu; Wei Liu

    2015-01-01

    Image enhancement is an important procedure of image processing and analysis. This paper presents a new technique using a modified measure and blending of cuckoo search and particle swarm optimization (CS-PSO) for low contrast images to enhance image adaptively. In this way, contrast enhancement is obtained by global transformation of the input intensities; it employs incomplete Beta function as the transformation function and a novel criterion for measuring image quality considering three fa...

  14. Advanced intensity-modulation continuous-wave lidar techniques for ASCENDS CO2 column measurements

    Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.; Harrison, F. W.; Obland, Michael D.; Meadows, Byron

    2015-10-01

    Global atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity- Modulated Continuous-Wave (IM-CW) lidar techniques are investigated as a means of facilitating CO2 measurements from space to meet the ASCENDS measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) modulation technique to uniquely discriminate surface lidar returns from intermediate aerosol and cloud contamination. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of optically thin clouds, thereby eliminating the need to correct for sidelobe bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new hyperfine interpolation techniques that takes advantage of the periodicity of the modulation waveforms. This approach works well for both BPSK and linear swept-frequency modulation techniques. The BPSK technique under investigation has excellent auto-correlation properties while possessing a finite bandwidth. A comparison of BPSK and linear swept-frequency is also discussed in this paper. These results are extended to include Richardson-Lucy deconvolution techniques to extend the resolution of the lidar beyond that implied by limit of the bandwidth of the modulation, where it is shown useful for making tree canopy measurements.

  15. Sustainable Modular Adaptive Redundancy Technique Emphasizing Partial Reconfiguration for Reduced Power Consumption

    R. Al-Haddad

    2011-01-01

    Full Text Available As reconfigurable devices' capacities and the complexity of applications that use them increase, the need for self-reliance of deployed systems becomes increasingly prominent. Organic computing paradigms have been proposed for fault-tolerant systems because they promote behaviors that allow complex digital systems to adapt and survive in demanding environments. In this paper, we develop a sustainable modular adaptive redundancy technique (SMART composed of a two-layered organic system. The hardware layer is implemented on a Xilinx Virtex-4 Field Programmable Gate Array (FPGA to provide self-repair using a novel approach called reconfigurable adaptive redundancy system (RARS. The software layer supervises the organic activities on the FPGA and extends the self-healing capabilities through application-independent, intrinsic, and evolutionary repair techniques that leverage the benefits of dynamic partial reconfiguration (PR. SMART was evaluated using a Sobel edge-detection application and was shown to tolerate stressful sequences of injected transient and permanent faults while reducing dynamic power consumption by 30% compared to conventional triple modular redundancy (TMR techniques, with nominal impact on the fault-tolerance capabilities. Moreover, PR is employed to keep the system on line while under repair and also to reduce repair time. Experiments have shown a 27.48% decrease in repair time when PR is employed compared to the full bitstream configuration case.

  16. An adaptive image enhancement technique by combining cuckoo search and particle swarm optimization algorithm.

    Ye, Zhiwei; Wang, Mingwei; Hu, Zhengbing; Liu, Wei

    2015-01-01

    Image enhancement is an important procedure of image processing and analysis. This paper presents a new technique using a modified measure and blending of cuckoo search and particle swarm optimization (CS-PSO) for low contrast images to enhance image adaptively. In this way, contrast enhancement is obtained by global transformation of the input intensities; it employs incomplete Beta function as the transformation function and a novel criterion for measuring image quality considering three factors which are threshold, entropy value, and gray-level probability density of the image. The enhancement process is a nonlinear optimization problem with several constraints. CS-PSO is utilized to maximize the objective fitness criterion in order to enhance the contrast and detail in an image by adapting the parameters of a novel extension to a local enhancement technique. The performance of the proposed method has been compared with other existing techniques such as linear contrast stretching, histogram equalization, and evolutionary computing based image enhancement methods like backtracking search algorithm, differential search algorithm, genetic algorithm, and particle swarm optimization in terms of processing time and image quality. Experimental results demonstrate that the proposed method is robust and adaptive and exhibits the better performance than other methods involved in the paper. PMID:25784928

  17. Fiber-wireless integrated mobile backhaul network based on a hybrid millimeter-wave and free-space-optics architecture with an adaptive diversity combining technique.

    Zhang, Junwen; Wang, Jing; Xu, Yuming; Xu, Mu; Lu, Feng; Cheng, Lin; Yu, Jianjun; Chang, Gee-Kung

    2016-05-01

    We propose and experimentally demonstrate a novel fiber-wireless integrated mobile backhaul network based on a hybrid millimeter-wave (MMW) and free-space-optics (FSO) architecture using an adaptive combining technique. Both 60 GHz MMW and FSO links are demonstrated and fully integrated with optical fibers in a scalable and cost-effective backhaul system setup. Joint signal processing with an adaptive diversity combining technique (ADCT) is utilized at the receiver side based on a maximum ratio combining algorithm. Mobile backhaul transportation of 4-Gb/s 16 quadrature amplitude modulation frequency-division multiplexing (QAM-OFDM) data is experimentally demonstrated and tested under various weather conditions synthesized in the lab. Performance improvement in terms of reduced error vector magnitude (EVM) and enhanced link reliability are validated under fog, rain, and turbulence conditions. PMID:27128036

  18. Parameters estimation based adaptive Generalized Projective Synchronization (GPS) of chaotic Chua’s circuit with application to chaos communication by parametric modulation

    In this paper we study the design and implementation of adaptive Generalized Projective Synchronization (GPS) problem between two chaotic circuits (master and slave) via a scalar transmitted signal and by a new method not requiring the same structure of master and slave circuits. Starting from a simple synchronization method, a renormalization technique enables us to design an adaptive observer (slave) of the known Chua’s circuit using simple and standard electronic components. This observer identifies some parameters proportional to values of components of the master with which it synchronizes through GPS when values of these parameters vary with time. Both numerical simulation and Pspice simulation of GPS for chaos communication by parametric modulation between the two circuits are performed

  19. Bit Error Rate Performance Analysis on Modulation Techniques of Wideband Code Division Multiple Access

    Masud, M A; Rahman, M A

    2010-01-01

    In the beginning of 21st century there has been a dramatic shift in the market dynamics of telecommunication services. The transmission from base station to mobile or downlink transmission using M-ary Quadrature Amplitude modulation (QAM) and Quadrature phase shift keying (QPSK) modulation schemes are considered in Wideband-Code Division Multiple Access (W-CDMA) system. We have done the performance analysis of these modulation techniques when the system is subjected to Additive White Gaussian Noise (AWGN) and multipath Rayleigh fading are considered in the channel. The research has been performed by using MATLAB 7.6 for simulation and evaluation of Bit Error Rate (BER) and Signal-To-Noise Ratio (SNR) for W-CDMA system models. It is shows that the analysis of Quadrature phases shift key and 16-ary Quadrature Amplitude modulations which are being used in wideband code division multiple access system, Therefore, the system could go for more suitable modulation technique to suit the channel quality, thus we can d...

  20. Analysis of BER of OFDM in Optical Domain with Different Modulation Techniques

    A. R. Gifty Arul Marin

    2013-01-01

    Full Text Available In OFDM system, the subcarrier frequencies are chosen so that the subcarriers are orthogonal to each other, meaning that cross talk between the sub channels is eliminated. Priority of OFDM system is given to minimizing the interference or crosstalk among the channels and symbols comprising the data stream. The primary advantage of OFDM is its ability to cope with severe channel conditions like attenuation of high frequencies, narrowband interference and frequency selective fading due to multipath. The existing OFDM systems were modelled based on frequency domain using various modulation techniques in AWGN channel. This is a research analysis to calculate the efficient BER of the OFDM system in the optical domain using BPSK and QPSK modulation techniques. This project can be used for high speed applications requiring more band width. Finally, performance comparison of BPSK and QPSK modulation schemes in OFDM system and the calculation of BER (Bit Error Rate using these modulation techniques is to be done. The entire OFDM system is implemented using SIMULINK tool in MATLAB

  1. Design and Development of Hybrid Multilevel Inverter employing Dual Reference Modulation Technique for Fuel Cell Applications

    R. Seyezhai

    2011-10-01

    Full Text Available MultiLevel Inverter (MLI has been recognized as an attractive topology for high voltage DC-AC conversion. This paper focuses on a new dual reference modulation technique for a hybrid multilevel inverter employing Silicon carbide (SiC switches for fuel cell applications. The proposed modulation technique employs two reference waveforms and a single inverted sine wave as the carrier waveform. This technique is compared with the conventional dual carrier waveform in terms of output voltage spectral quality and switching losses. An experimental five-level hybrid inverter test rig has been built using SiC switches to implement the proposed algorithm. Gating signals are generated using PIC microcontroller. The performance of the inverter has been analyzed and compared with the result obtained from theory and simulation. Simulation study of Proportional Integral (PI controller for the inverter employing the proposed modulation strategy has been done in MATLAB/SIMULINK. Keywords: Multilevel inverter, SiC , dual reference modulation, switching losses, PI

  2. Nuclear Technology. Course 32: Nondestructive Examination (NDE) Techniques II. Module 32-5, Fundamentals of Eddy Current Testing.

    Espy, John

    This fifth in a series of six modules for a course titled Nondestructive Examination (NDE) Techniques II describes the fundamental concepts applicable to eddy current testing in general. The module follows a typical format that includes the following sections: (1) introduction, (2) module prerequisites, (3) objectives, (4) notes to…

  3. Nuclear Technology. Course 32: Nondestructive Examination (NDE) Techniques II. Module 32-6, Operation of Eddy Current Test Equipment.

    Espy, John; Selleck, Ben

    This sixth in a series of six modules for a course titled Nondestructive Examination (NDE) Techniques II details eddy current examination of steam generator tubing. The module follows a typical format that includes the following sections: (1) introduction, (2) module prerequisites, (3) objectives, (4) notes to instructor/student, (5) subject…

  4. Beam orientation optimization for intensity modulated radiation therapy using adaptive l2,1-minimization

    Jia, Xun; Men, Chunhua; Lou, Yifei; Jiang, Steve B.

    2011-10-01

    Beam orientation optimization (BOO) is a key component in the process of intensity modulated radiation therapy treatment planning. It determines to what degree one can achieve a good treatment plan in the subsequent plan optimization process. In this paper, we have developed a BOO algorithm via adaptive l2, 1-minimization. Specifically, we introduce a sparsity objective function term into our model which contains weighting factors for each beam angle adaptively adjusted during the optimization process. Such an objective function favors a small number of beam angles. By optimizing a total objective function consisting of a dosimetric term and the sparsity term, we are able to identify unimportant beam angles and gradually remove them without largely sacrificing the dosimetric objective. In one typical prostate case, the convergence property of our algorithm, as well as how beam angles are selected during the optimization process, is demonstrated. Fluence map optimization (FMO) is then performed based on the optimized beam angles. The resulting plan quality is presented and is found to be better than that of equiangular beam orientations. We have further systematically validated our algorithm in the contexts of 5-9 coplanar beams for five prostate cases and one head and neck case. For each case, the final FMO objective function value is used to compare the optimized beam orientations with the equiangular ones. It is found that, in the majority of cases tested, our BOO algorithm leads to beam configurations which attain lower FMO objective function values than those of corresponding equiangular cases, indicating the effectiveness of our BOO algorithm. Superior plan qualities are also demonstrated by comparing DVH curves between BOO plans and equiangular plans.

  5. Sliding mode pulse-width modulation technique for direct torque controlled induction motor drive

    Bounadja, M.; Belarbi, A. W.; Belmadani, B.

    2010-05-01

    This paper presents a novel pulse-width modulation technique based sliding mode approach for direct torque control of an induction machine drive. Methodology begins with a sliding mode control of machine's torque and stator flux to generate the reference voltage vector and to reduce parameters sensitivity. Then, the switching control of the three-phase inverter is developed using sliding mode concept to make the system tracking reference voltage inputs. The main features of the proposed methodologies are the high tracking accuracy and the much easier implementation compared to the space vector modulation. Simulations are carried out to confirm the effectiveness of proposed control algorithms.

  6. Pulsed laser deposition: the road to hybrid nanocomposites coatings and novel pulsed laser adaptive technique.

    Serbezov, Valery

    2013-01-01

    The applications of Pulsed Laser Deposition (PLD) for producing nanoparticles, nanostructures and nanocomposites coatings based on recently developed laser ablating techniques and their convergence are being reviewed. The problems of in situ synthesis of hybrid inorganic-organic nanocomposites coatings by these techniques are being discussed. The novel modification of PLD called Pulsed Laser Adaptive Deposition (PLAD) technique is presented. The in situ synthesized inorganic/organic nanocomposites coatings from Magnesium (Mg) alloy/Rhodamine B and Mg alloy/ Desoximetasone by PLAD are described. The trends, applications and future development of discussed patented methods based on the laser ablating technologies for producing hybrid nanocomposite coatings have also been discussed in this review. PMID:22747717

  7. Adaptable Web Modules to Stimulate Active Learning in Engineering Hydrology using Data and Model Simulations of Three Regional Hydrologic Systems

    Habib, E. H.; Tarboton, D. G.; Lall, U.; Bodin, M.; Rahill-Marier, B.; Chimmula, S.; Meselhe, E. A.; Ali, A.; Williams, D.; Ma, Y.

    2013-12-01

    server-based system. Open source web technologies and community-based tools are used to facilitate wide dissemination and adaptation by diverse, independent institutions. The new hydrologic learning modules are based on recent developments in hydrologic modeling, data, and resources. The modules are embedded in three regional-scale ecosystems, Coastal Louisiana, Florida Everglades, and Utah Great Salt Lake Basin. These sites provide a wealth of hydrologic concepts and scenarios that can be used in most water resource and hydrology curricula. The study develops several learning modules based on the three hydro-systems covering subjects such as: water-budget analysis, effects of human and natural changes, climate-hydrology teleconnections, and water-resource management scenarios. The new developments include an instructional interface to give critical guidance and support to the learner and an instructor's guide containing adaptation and implementation procedures to assist instructors in adopting and integrating the material into courses and provide a consistent experience. The design of the new hydrologic education developments will be transferable to independent institutions and adaptable both instructionally and technically through a server system capable of supporting additional developments by the educational community.

  8. ADAPTING E-COURSES USING DATA MINING TECHNIQUES - PDCA APPROACH AND QUALITY SPIRAL

    Marija Blagojevic

    2013-09-01

    Full Text Available This paper presents an approach to adapting e-courses based on original PDCA (Plan, Do, Check , Act platform and quality spiral. An algorithm for the adaptation of e-courses was proposed and implemented into the Moodle Learning Management System at the Faculty of Technical Sciences, Cacak. The approach is primarily based on improving LMS (Learning Management Systems or e-learning systems through modifying the electronic structure of the courses by predicting the behaviour patterns of the users. The prediction of user behaviour patterns was done using data mining techniques. Future research will focus on modelling of excellence of continuous advancement of the original system based on the evaluation results carried out at the end of each PDCA cycle. Additionally, future work will aim at evaluating the effects of the system based on the achievements and positive feedback of the users.

  9. A spectral identification technique for adaptive attitude control and pointing of the Space Telescope

    Teuber, D. L.

    1976-01-01

    The Space Telescope is a 2.4 m class aperture optical telescope having near-diffraction-limited performance. It will be placed into earth orbit by 1980 via the Space Shuttle. The problem considered is how to achieve negligible degradation of the astronomy imaging capability (to 0.005 arc second) due to smearing by pointing motions during observations. Initially, pointing instability sources were identified and a linear stability was used to assess the magnitude of elastic body modes and to design control system compensation regions necessary for subsequent adaptive control. A spectral identification technique for this adaptive attitude control and pointing has been investigated that will alleviate requirements for comprehensive dynamic ground testing. Typical all-digital simulation results describing motions of the telescope line of sight are presented.

  10. The Service Laboratory - A GTZ-BgVV project: Health protection through adapted veterinary diagnostic techniques

    The customary diagnostic methods of today have been developed in industrialized countries. High costs for personnel resulted in a trend towards automation and prefabricated test kits. Consequently, these techniques are not sufficiently adapted to local conditions in developing countries, where, as a rule, skilled and ancillary staff is available whereas foreign currency reserves for purchasing laboratory equipment and material from abroad are rather limited. Furthermore, the training of personnel from developing countries has usually been oriented towards thenon-transferable standards and methods of industrialized countries. This leads to a long term dependence of the diagnostic services on external funding. A diagnostic technology adapted to the specific local conditions of developing countries is needed to overcome this situation. The project activities concentrate on serological diagnostic work. Here, basic knowledge of the common diagnostic techniques and their set-up for specific diseases, methods for the production of related reagents (antigens, antibodies, conjugates, complement, etc.) and cleaning procedures for the reuse of 'one way' plastic material is spread by training programmes, specific publications and information leaflets. For two of the more complex test procedures, the most frequently quoted prescribed test for international trade, CFT, and the increasingly important ELISA (OIE, Manual of Standards for Diagnostic Techniques, Paris, 1992), we have calculated the cost reduction potential of adaptation through self-production of reagents and reuse of plastic materials. Material costs per microtitre test plate for the diagnosis of brucellosis can be reduced from US $3.79 to 0.82 for CFT and from US $3.88 to 1.13 for ELISA. In comparison, commercial ELISA kits cost about US $80 to 90 per plate (e.g. Bommeli, IDEXX, Boehringer)

  11. GPS-based ionospheric tomography with a constrained adaptive simultaneous algebraic reconstruction technique

    Wen Debao; Zhang Xiao; Tong Yangjin; Zhang Guangsheng; Zhang Min; Leng Rusong

    2015-03-01

    In this paper, a constrained adaptive simultaneous algebraic reconstruction technique (CASART) is presented to obtain high-quality reconstructions from insufficient projections. According to the continuous smoothness of the variations of ionospheric electron density (IED) among neighbouring voxels, Gauss weighted function is introduced to constrain the tomography system in the new method. It can resolve the dependence on the initial values for those voxels without any GPS rays traversing them. Numerical simulation scheme is devised to validate the feasibility of the new algorithm. Some comparisons are made to demonstrate the superiority of the new method. Finally, the actual GPS observations are applied to further validate the feasibility and superiority of the new algorithm.

  12. Design of the 12-bit Delta-Sigma Modulator using SC Technique for Vibration Sensor Output Processing

    M. Pavlik

    2012-04-01

    Full Text Available The work deals with the design of the 12-bit Delta-Sigma modulator using switched capacitors (SC technique. The modulator serves to vibration sensor output processing. The first part describes the Delta-Sigma modulator parameters definition. Results of the proposed topology ideal model were presented as well. Next, the Delta-Sigma modulator circuitry on the transistor level was done. The ONSemiconductor I2T100 0.7 um CMOS technology was used for design. Then, the Delta-Sigma modulator nonidealities were simulated and implemented into the MATLAB ideal model of the modulator. The model of real Delta-Sigma modulator was derived. Consequently, modulator coefficients were optimized. Finally, the corner analysis of the Delta-Sigma modulator with the optimized coefficients was simulated. The value of SNDR = 82.2 dB (ENOB = 13.4 bits was achieved.

  13. EXPERIMENTAL INVESTIGATION OF THERMOELECTRIC GENERATOR MODULES WITH DIFFERENT TECHNIQUE OF COOLING SYSTEM

    Mohd Izam Abd Jalil

    2013-01-01

    Full Text Available Nowadays the world has experiencing global warming due to excessive energy release into atmospheres. Today, a lot of research being conducted on ways to recover or reused the energy losses. An experimental investigation has been carried out to identify the most suitable cooling system techniques to achieve a stable and sustainable power output. Four types of Thermoelectric Module (TEM was fitted and tested on different cooling system techniques. Testing was conducted using a candle flame as a heat source to produce a suitable temperature with the maximum temperature of 200°C. An electronic circuit is used to provide a constant and sufficient power. The use of suitable cooling system and TEM was found by investigating the module parameters such as the temperature different of hot to cold side, number of thermo elements and internal resistance. This research contributes an important role in saving energy and reducing the dependency to primary energy sources (AC power or battery.

  14. Adaptively Reevaluated Bayesian Localization (ARBL): A novel technique for radiological source localization

    Miller, Erin A.; Robinson, Sean M.; Anderson, Kevin K.; McCall, Jonathon D.; Prinke, Amanda M.; Webster, Jennifer B.; Seifert, Carolyn E.

    2015-06-01

    We present a novel technique for the localization of radiological sources in urban or rural environments from an aerial platform. The technique is based on a Bayesian approach to localization, in which measured count rates in a time series are compared with predicted count rates from a series of pre-calculated test sources to define likelihood. This technique is expanded by using a localized treatment with a limited field of view (FOV), coupled with a likelihood ratio reevaluation, allowing for real-time computation on commodity hardware for arbitrarily complex detector models and terrain. In particular, detectors with inherent asymmetry of response (such as those employing internal collimation or self-shielding for enhanced directional awareness) are leveraged by this approach to provide improved localization. Results from the localization technique are shown for simulated flight data using monolithic as well as directionally-aware detector models, and the capability of the methodology to locate radioisotopes is estimated for several test cases. This localization technique is shown to facilitate urban search by allowing quick and adaptive estimates of source location, in many cases from a single flyover near a source. In particular, this method represents a significant advancement from earlier methods like full-field Bayesian likelihood, which is not generally fast enough to allow for broad-field search in real time, and highest-net-counts estimation, which has a localization error that depends strongly on flight path and cannot generally operate without exhaustive search.

  15. Adaptively Reevaluated Bayesian Localization (ARBL). A Novel Technique for Radiological Source Localization

    Miller, Erin A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Robinson, Sean M. [Pacific Northwest National Lab. (PNNL), Seattle, WA (United States); Anderson, Kevin K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McCall, Jonathon D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Prinke, Amanda M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Webster, Jennifer B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Seifert, Carolyn E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-01-19

    Here we present a novel technique for the localization of radiological sources in urban or rural environments from an aerial platform. The technique is based on a Bayesian approach to localization, in which measured count rates in a time series are compared with predicted count rates from a series of pre-calculated test sources to define likelihood. Furthermore, this technique is expanded by using a localized treatment with a limited field of view (FOV), coupled with a likelihood ratio reevaluation, allowing for real-time computation on commodity hardware for arbitrarily complex detector models and terrain. In particular, detectors with inherent asymmetry of response (such as those employing internal collimation or self-shielding for enhanced directional awareness) are leveraged by this approach to provide improved localization. Our results from the localization technique are shown for simulated flight data using monolithic as well as directionally-aware detector models, and the capability of the methodology to locate radioisotopes is estimated for several test cases. This localization technique is shown to facilitate urban search by allowing quick and adaptive estimates of source location, in many cases from a single flyover near a source. In particular, this method represents a significant advancement from earlier methods like full-field Bayesian likelihood, which is not generally fast enough to allow for broad-field search in real time, and highest-net-counts estimation, which has a localization error that depends strongly on flight path and cannot generally operate without exhaustive search

  16. Adaptively Reevaluated Bayesian Localization (ARBL): A novel technique for radiological source localization

    We present a novel technique for the localization of radiological sources in urban or rural environments from an aerial platform. The technique is based on a Bayesian approach to localization, in which measured count rates in a time series are compared with predicted count rates from a series of pre-calculated test sources to define likelihood. This technique is expanded by using a localized treatment with a limited field of view (FOV), coupled with a likelihood ratio reevaluation, allowing for real-time computation on commodity hardware for arbitrarily complex detector models and terrain. In particular, detectors with inherent asymmetry of response (such as those employing internal collimation or self-shielding for enhanced directional awareness) are leveraged by this approach to provide improved localization. Results from the localization technique are shown for simulated flight data using monolithic as well as directionally-aware detector models, and the capability of the methodology to locate radioisotopes is estimated for several test cases. This localization technique is shown to facilitate urban search by allowing quick and adaptive estimates of source location, in many cases from a single flyover near a source. In particular, this method represents a significant advancement from earlier methods like full-field Bayesian likelihood, which is not generally fast enough to allow for broad-field search in real time, and highest-net-counts estimation, which has a localization error that depends strongly on flight path and cannot generally operate without exhaustive search

  17. Novel zero-voltage switching techniques for pulse-width-modulated converters

    Hua, Guichao

    1991-01-01

    Two new classes of soft switching pulse-width-modulated (PWM) converters, named zero-voltage-switched (ZVS) PWM converters and zero-voltage-transition (ZVT) PWM converters, are proposed. The proposed ZVS-PWM converters combine the merits of conventional PWM and ZVS-QRC techniques. They are capable of regulating the output for a wide load and input voltage range while maintaining constant-frequency operation. By employing a saturable inductor, the load range under which ZVS i...

  18. The radiation techniques of tomotherapy & intensity-modulated radiation therapy applied to lung cancer

    Zhu, Zhengfei; Fu, Xiaolong

    2015-01-01

    Radiotherapy (RT) plays an important role in the management of lung cancer. Development of radiation techniques is a possible way to improve the effect of RT by reducing toxicities through better sparing the surrounding normal tissues. This article will review the application of two forms of intensity-modulated radiation therapy (IMRT), fixed-field IMRT and helical tomotherapy (HT) in lung cancer, including dosimetric and clinical studies. The advantages and potential disadvantages of these t...

  19. Volumetric-Modulated Arc Therapy for Stereotactic Body Radiotherapy of Lung Tumors: A Comparison With Intensity-Modulated Radiotherapy Techniques

    Purpose: To demonstrate the potential of volumetric-modulated arc therapy (VMAT) compared with intensity-modulated radiotherapy (IMRT) techniques with a limited number of segments for stereotactic body radiotherapy (SBRT) for early-stage lung cancer. Methods and Materials: For a random selection of 27 patients eligible for SBRT, coplanar and noncoplanar IMRT and coplanar VMAT (using SmartArc) treatment plans were generated in Pinnacle3 and compared. In addition, film measurements were performed using an anthropomorphic phantom to evaluate the skin dose for the different treatment techniques. Results: Using VMAT, the delivery times could be reduced to an average of 6.6 min compared with 23.7 min with noncoplanar IMRT. The mean dose to the healthy lung was 4.1 Gy for VMAT and noncoplanar IMRT and 4.2 Gy for coplanar IMRT. The volume of healthy lung receiving >5 Gy and >20 Gy was 18.0% and 5.4% for VMAT, 18.5% and 5.0% for noncoplanar IMRT, and 19.4% and 5.7% for coplanar IMRT, respectively. The dose conformity at 100% and 50% of the prescribed dose of 54 Gy was 1.13 and 5.17 for VMAT, 1.11 and 4.80 for noncoplanar IMRT and 1.12 and 5.31 for coplanar IMRT, respectively. The measured skin doses were comparable for VMAT and noncoplanar IMRT and slightly greater for coplanar IMRT. Conclusions: Coplanar VMAT for SBRT for early-stage lung cancer achieved plan quality and skin dose levels comparable to those using noncoplanar IMRT and slightly better than those with coplanar IMRT. In addition, the delivery time could be reduced by ≤70% with VMAT.

  20. Implementation of pulse interval modulation based on dualmapping technique for optical wireless communications

    ZHANG Tie-ying; WANG Hong-xing; HU Hao; CONG Pei-sheng

    2009-01-01

    Aiming at implementing the digital pulse interval modulation (DPIM) for optical wireless communications (OWC), a dual-mapping technique is presented. The scheme of DPIM train based upon the dual-mapping technique is given. Its slot error rate is derived for the avalanche photonic diode (APD) receiver model, and is compared with that of classical DPIM. Simulation results show that the dual-mapping DPIM (D-DPIM), which has a fixed slot length, only has marginally inferior error performance, but can solve waiting slots or buffer overflowing in comparison with DPIM. Hence, it is suitable for the optical wireless communication systems.

  1. Advanced digital modulation: Communication techniques and monolithic GaAs technology

    Wilson, S. G.; Oliver, J. D., Jr.; Kot, R. C.; Richards, C. R.

    1983-01-01

    Communications theory and practice are merged with state-of-the-art technology in IC fabrication, especially monolithic GaAs technology, to examine the general feasibility of a number of advanced technology digital transmission systems. Satellite-channel models with (1) superior throughput, perhaps 2 Gbps; (2) attractive weight and cost; and (3) high RF power and spectrum efficiency are discussed. Transmission techniques possessing reasonably simple architectures capable of monolithic fabrication at high speeds were surveyed. This included a review of amplitude/phase shift keying (APSK) techniques and the continuous-phase-modulation (CPM) methods, of which MSK represents the simplest case.

  2. [The diagnostics of adaptive reactions of blood on application the stress-modulating therapy in patients with brain chronic ischemia].

    Krylov, V N; Deriugina, A V; Antipenko, E A; Zakharova, O A

    2012-12-01

    The article deals with the results of analysis of electrophoretic mobility of erythrocytes and leukogram in patients with dyscirculatory encephalopathy on different stages of disease on application therapy with inclusion of stress-modulating pharmaceuticals into course of treatment. It is established that the electrophoretic mobiliy of erythrocytes makes it possible to evaluate the adaptive indicators blood in patients with dyscirculatory encephalopathy. The consideration of these indicators makes feasible the substantiation of inclusion of stress-modulating therapy into complex treatment of patients with chronic cerebrovascular inefficiency. PMID:23479969

  3. Adaptive Finite Element Modeling Techniques for the Poisson-Boltzmann Equation

    Holst, Michael; Yu, Zeyun; Zhou, Yongcheng; Zhu, Yunrong

    2010-01-01

    We develop an efficient and reliable adaptive finite element method (AFEM) for the nonlinear Poisson-Boltzmann equation (PBE). We first examine the regularization technique of Chen, Holst, and Xu; this technique made possible the first a priori pointwise estimates and the first complete solution and approximation theory for the Poisson-Boltzmann equation. It also made possible the first provably convergent discretization of the PBE, and allowed for the development of a provably convergent AFEM for the PBE. However, in practice the regularization turns out to be numerically ill-conditioned. In this article, we examine a second regularization, and establish a number of basic results to ensure that the new approach produces the same mathematical advantages of the original regularization, without the ill-conditioning property. We then design an AFEM scheme based on the new regularized problem, and show that the resulting AFEM scheme is accurate and reliable, by proving a contraction result for the error. This res...

  4. Blind Adaptive Subcarrier Combining Technique for MC-CDMA Receiver in Mobile Rayleigh Channel

    Shakya, Indu; Stipidis, Elias

    2011-01-01

    A new subcarrier combining technique is proposed for MC -CDMA receiver in mobile Rayleigh fading channel. It exploits the structure formed by repeating spreading sequences of users on different subcarriers to simultaneously suppress multiple access interference (MAI) and provide implicit channel tracking without any knowledge of the channel amplitudes or training sequences. This is achieved by adaptively weighting each subcarrier in each symbol period by employing a simple gradient descent algorithm to meet the constant modulus (CM) criterion with judicious selection of step-size. Improved BER and user capacity performance are shown with similar complexity in order of O(N) compared with conventional maximum ratio combining and equal gain combining techniques even under high channel Doppler rates.

  5. Adaptive technique for matching the spectral response in skin lesions' images

    Pavlova, P.; Borisova, E.; Pavlova, E.; Avramov, L.

    2015-03-01

    The suggested technique is a subsequent stage for data obtaining from diffuse reflectance spectra and images of diseased tissue with a final aim of skin cancer diagnostics. Our previous work allows us to extract patterns for some types of skin cancer, as a ratio between spectra, obtained from healthy and diseased tissue in the range of 380 - 780 nm region. The authenticity of the patterns depends on the tested point into the area of lesion, and the resulting diagnose could also be fixed with some probability. In this work, two adaptations are implemented to localize pixels of the image lesion, where the reflectance spectrum corresponds to pattern. First adapts the standard to the personal patient and second - translates the spectrum white point basis to the relative white point of the image. Since the reflectance spectra and the image pixels are regarding to different white points, a correction of the compared colours is needed. The latest is done using a standard method for chromatic adaptation. The technique follows the steps below: -Calculation the colorimetric XYZ parameters for the initial white point, fixed by reflectance spectrum from healthy tissue; -Calculation the XYZ parameters for the distant white point on the base of image of nondiseased tissue; -Transformation the XYZ parameters for the test-spectrum by obtained matrix; -Finding the RGB values of the XYZ parameters for the test-spectrum according sRGB; Finally, the pixels of the lesion's image, corresponding to colour from the test-spectrum and particular diagnostic pattern are marked with a specific colour.

  6. Possibilities of joint application of adaptive optics technique and nonlinear optical phase conjugation to compensate for turbulent distortions

    Lukin, V. P.; Kanev, F. Yu; Kulagin, O. V.

    2016-05-01

    The efficiency of integrating the nonlinear optical technique based on forming a reverse wavefront and the conventional adaptive optics into a unified complex (for example, for adaptive focusing of quasi-cw laser radiation) is demonstrated. Nonlinear optical phase conjugation may provide more exact information about the phase fluctuations in the corrected wavefront in comparison with the adaptive optics methods. At the same time, the conventional methods of adaptive optics provide an efficient control of a laser beam projected onto a target for a rather long time.

  7. Tangential volumetric modulated arc therapy technique for left-sided breast cancer radiotherapy

    The aim of the present study was to introduce a new restricted tangential volumetric modulated arc therapy (tVMAT) technique for whole breast irradiation and compare its dosimetric properties to other currently used breast cancer radiotherapy techniques. Ten consecutive women with left-sided breast cancer were enrolled in this retrospective study. Four treatment plans were generated for each patient: 1) standard tangential field-in-field (FinF), 2) tangential intensity modulated radiotherapy (tIMRT), 3) tangential VMAT (tVMAT) with two dual arcs of 50-60° and 4) continuous VMAT (cVMAT) with a dual arc of 240°. The plans were created with Monaco® (tIMRT, tVMAT and cVMAT) and Oncentra® (FinF) treatment planning systems. With both VMAT techniques significantly higher cardiac avoidance, dose coverage and dose homogenity were achieved when compared with FinF or tIMRT techniques (p < 0.01). VMAT techniques also decreased the high dose areas (above 20 Gy) of ipsilateral lung. There were no significant differences in the mean dose of contralateral breast between the tVMAT, tIMRT and FinF techniques. The dose coverage (V47.5 Gy) was greatest with cVMAT. However, with cVMAT the increase of contralateral breast dose was significant. The present results support the hypothesis that the introduced tVMAT technique is feasible for treatment of left-sided breast cancer. With tVMAT dose to heart and ipsilateral lung can be reduced and the dose homogeneity can be improved without increasing the dose to contralateral breast or lung

  8. Adaptation des techniques de forage à la recherche et à l'équipement des stockages souterrains de gaz naturel Adapting Drilling Techniques to the Search for and Equipment of Underground Natural-Gas Storage Facilities

    Grandin J.

    2006-11-01

    Full Text Available Pour répondre à la modulation annuelle de la consommation de gaz, le Gaz de France a décidé, il y a une trentaine d'années, de stocker du gaz, soit dans des nappes aquifères, soit dans des cavités salines. La recherche de structures géologiques aptes à recevoir ce gaz, la réalisation et l'équipement de puits d'exploration ou d'exploitation, l'entretien de ces puits et le contrôle des stockages ont été confiés au Département réservoirs souterrains de la Direction des études et techniques nouvelles. Les phases d'exploration et de développement d'un stockage souterrain nécessitent le forage de puits du type pétrolier. Ces sondages permettent, d'une part la récupération d'un maximum de renseignements concernant les différentes couches géologiques traversées et l'évaluation de leur aptitude à stocker le gaz, et d'autre part, d'assurer une exploitation optimale et fiable du stockage dans les meilleures conditions de sécurité. La pratique acquise dans l'exécution de ces forages par le Gaz de France lui a permis d'adapter aux stockages souterrains de nombreuses techniques des forages pétroliers. Parallèlement des procédés originaux ont pu être mis au point pour répondre à certaines exigences particulières du forage des puits de réservoirs souterrains, notamment à celles concernant le bon calibrage du trou foré ou la qualité des cimentations des cuvelages. L'article présente l'ensemble de ces adaptationset pratiques originales; bien que ne prétendant rien d'autre qu'apporter une contribution au chapitre problèmes particuliers des forages pour stockages souterrains de la technique pétrolière, certaines de celles-ci devraient pouvoir, en retour, trouver des applications intéressantes dans les forages pétroliers de moyenne profondeur. About 30 years ago and with a view to keep pace with the annual variation of gas consumption, Gaz de France decided to store gas in either aquifer layers or salt cavities. The

  9. SU-E-J-70: Evaluation of Multiple Isocentric Intensity Modulated and Volumetric Modulated Arc Therapy Techniques Using Portal Dosimetry

    Purpose: To develop a method for verification of dose distribution in a patient during treatment using multiple isocentric Intensity modulated and volumetric modulated arc therapy techniques with portal dosimetry. Methods: Varian True Beam accelerator, equipped with an aS1000 megavoltage electronic portal imaging device (EPID) has an integrated image mode for portal dosimetry (PD). The source-to-imager distance was taken at 150 cm to avoid collision to the table. Fourteen fractions were analyzed for this study. During shift in a single plan from one isocenter to another isocenter, EPID also shifted longitudinally for each field by taking the extent of divergence of beam into the consideration for EPID distance of 150cm. Patients were given treatment everyday with EPID placed in proper position for each field. Several parameters were obtained by comparing the dose distribution between fractions to fraction. The impact of the intra-fraction and inter-fraction of the patient in combination with isocenter shift of the beams were observed. Results: During treatment, measurements were performed by EPID and were evaluated by the gamma method. Analysis was done between fractions for multiple isocenter treatments. The pass rates of the gamma analysis with a criterion of 3% and 3 mm for the 14 fractions were over 97.8% with good consistency. Whereas maximum gamma exceeded the criteria in few fractions (in<1 cc vol). Average gamma was observed in the criteria of 0.5%. Maximum dose difference and average dose differences were less than 0.22 CU and 0.01 CU for maximum tolerance of 1.0 CU and 0.2 CU respectively. Conclusion: EPID with extended distance is ideal method to verify the multiple isocentric dose distribution in patient during treatment, especially cold and hot spots in junction dose. Verification of shifts as well as the dose differences between each fraction due to inter-fraction and intra-fraction of the patient can be derived

  10. APPLICATION OF SUBBAND ADAPTIVE THRESHOLDING TECHNIQUE WITH NEIGHBOURHOOD PIXEL FILTERING FOR DENOISING MRI IMAGES

    S. KALAVATHY

    2012-02-01

    Full Text Available The image de-noising naturally corrupted by noise is a classical problem in the field of signal or image processing. Image denoising has become an essential exercise in medical imaging especially the Magnetic Resonance Imaging (MRI..We propose a new method for MRI restoration. Because MR magnitude images suffer from a contrast-reducing signal-dependent bias. Also the noise is often assumed to be white, however a widely used acquisition technique to decrease the acquisition time gives rise to correlated noise. Subband adaptive thresholding technique based on wavelet coefficient along with Neighbourhood Pixel Filtering Algorithm (NPFA for noise suppression of Magnetic Resonance Images (MRI is presented in this paper. Astatistical model is proposed to estimate the noise variance for each coefficient based on the subband using Maximum Likelihood (ML estimator or a Maximum a Posterior (MAP estimator. Also this model describes a new method for suppression of noise by fusing the wavelet denoising technique with optimized thresholding function. This is achieved by including a multiplying factor (α to make the threshold value dependent on decomposition level. By finding Neighbourhood Pixel Difference (NPD and adding NPFA along with subband thresholding the clarity of the image is improved. The filtered value is generated by minimizing NPD and Weighted Mean Square Error (WMSE using method of leastsquare.Areduction in noise pixel is well observedon replacing the optimal weight namely NPFA filter solution with the noisy value of the current pixel. Due to this NPFA filter gains the effect of both high pass and low pass filter. Hence the proposed technique yields significantly superior image quality by preserving the edges, producing a better PSNR value. To confirm the efficiency this is further compared with Median filter, Weiner Filter, Subband thresholding technique along with NPFA filter.

  11. Comparison of adaptive statistical iterative and filtered back projection reconstruction techniques in brain CT

    Purpose: To compare image quality and visualization of normal structures and lesions in brain computed tomography (CT) with adaptive statistical iterative reconstruction (ASIR) and filtered back projection (FBP) reconstruction techniques in different X-ray tube current–time products. Materials and methods: In this IRB-approved prospective study, forty patients (nineteen men, twenty-one women; mean age 69.5 ± 11.2 years) received brain scan at different tube current–time products (300 and 200 mAs) in 64-section multi-detector CT (GE, Discovery CT750 HD). Images were reconstructed with FBP and four levels of ASIR-FBP blending. Two radiologists (please note that our hospital is renowned for its geriatric medicine department, and these two radiologists are more experienced in chronic cerebral vascular disease than in neoplastic disease, so this research did not contain cerebral tumors but as a discussion) assessed all the reconstructed images for visibility of normal structures, lesion conspicuity, image contrast and diagnostic confidence in a blinded and randomized manner. Volume CT dose index (CTDIvol) and dose-length product (DLP) were recorded. All the data were analyzed by using SPSS 13.0 statistical analysis software. Results: There was no statistically significant difference between the image qualities at 200 mAs with 50% ASIR blending technique and 300 mAs with FBP technique (p > .05). While between the image qualities at 200 mAs with FBP and 300 mAs with FBP technique a statistically significant difference (p < .05) was found. Conclusion: ASIR provided same image quality and diagnostic ability in brain imaging with greater than 30% dose reduction compared with FBP reconstruction technique

  12. Comparison of adaptive statistical iterative and filtered back projection reconstruction techniques in brain CT

    Ren, Qingguo, E-mail: renqg83@163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Dewan, Sheilesh Kumar, E-mail: sheilesh_d1@hotmail.com [Department of Geriatrics, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Li, Ming, E-mail: minli77@163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Li, Jianying, E-mail: Jianying.Li@med.ge.com [CT Imaging Research Center, GE Healthcare China, Beijing (China); Mao, Dingbiao, E-mail: maodingbiao74@163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Wang, Zhenglei, E-mail: Williswang_doc@yahoo.com.cn [Department of Radiology, Shanghai Electricity Hospital, Shanghai 200050 (China); Hua, Yanqing, E-mail: cjr.huayanqing@vip.163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China)

    2012-10-15

    Purpose: To compare image quality and visualization of normal structures and lesions in brain computed tomography (CT) with adaptive statistical iterative reconstruction (ASIR) and filtered back projection (FBP) reconstruction techniques in different X-ray tube current–time products. Materials and methods: In this IRB-approved prospective study, forty patients (nineteen men, twenty-one women; mean age 69.5 ± 11.2 years) received brain scan at different tube current–time products (300 and 200 mAs) in 64-section multi-detector CT (GE, Discovery CT750 HD). Images were reconstructed with FBP and four levels of ASIR-FBP blending. Two radiologists (please note that our hospital is renowned for its geriatric medicine department, and these two radiologists are more experienced in chronic cerebral vascular disease than in neoplastic disease, so this research did not contain cerebral tumors but as a discussion) assessed all the reconstructed images for visibility of normal structures, lesion conspicuity, image contrast and diagnostic confidence in a blinded and randomized manner. Volume CT dose index (CTDI{sub vol}) and dose-length product (DLP) were recorded. All the data were analyzed by using SPSS 13.0 statistical analysis software. Results: There was no statistically significant difference between the image qualities at 200 mAs with 50% ASIR blending technique and 300 mAs with FBP technique (p > .05). While between the image qualities at 200 mAs with FBP and 300 mAs with FBP technique a statistically significant difference (p < .05) was found. Conclusion: ASIR provided same image quality and diagnostic ability in brain imaging with greater than 30% dose reduction compared with FBP reconstruction technique.

  13. A novel sliding-mode control of induction motor using space vector modulation technique.

    Fu, Tian-Jun; Xie, Wen-Fang

    2005-10-01

    This paper presents a novel sliding-mode control method for torque control of induction motors. The control principle is based on sliding-mode control combined with space vector modulation technique. The sliding-mode control contributes to the robustness of induction motor drives, and the space vector modulation improves the torque, flux, and current steady-state performance by reducing the ripple. The Lyapunov direct method is used to ensure the reaching and sustaining of sliding mode and stability of the control system. The performance of the proposed system is compared with those of conventional sliding-mode controller and classical PI controller. Finally, computer simulation results show that the proposed control scheme provides robust dynamic characteristics with low torque ripple. PMID:16294775

  14. Adapt

    Bargatze, L. F.

    2015-12-01

    Active Data Archive Product Tracking (ADAPT) is a collection of software routines that permits one to generate XML metadata files to describe and register data products in support of the NASA Heliophysics Virtual Observatory VxO effort. ADAPT is also a philosophy. The ADAPT concept is to use any and all available metadata associated with scientific data to produce XML metadata descriptions in a consistent, uniform, and organized fashion to provide blanket access to the full complement of data stored on a targeted data server. In this poster, we present an application of ADAPT to describe all of the data products that are stored by using the Common Data File (CDF) format served out by the CDAWEB and SPDF data servers hosted at the NASA Goddard Space Flight Center. These data servers are the primary repositories for NASA Heliophysics data. For this purpose, the ADAPT routines have been used to generate data resource descriptions by using an XML schema named Space Physics Archive, Search, and Extract (SPASE). SPASE is the designated standard for documenting Heliophysics data products, as adopted by the Heliophysics Data and Model Consortium. The set of SPASE XML resource descriptions produced by ADAPT includes high-level descriptions of numerical data products, display data products, or catalogs and also includes low-level "Granule" descriptions. A SPASE Granule is effectively a universal access metadata resource; a Granule associates an individual data file (e.g. a CDF file) with a "parent" high-level data resource description, assigns a resource identifier to the file, and lists the corresponding assess URL(s). The CDAWEB and SPDF file systems were queried to provide the input required by the ADAPT software to create an initial set of SPASE metadata resource descriptions. Then, the CDAWEB and SPDF data repositories were queried subsequently on a nightly basis and the CDF file lists were checked for any changes such as the occurrence of new, modified, or deleted

  15. Acceptance and Mindfulness Techniques as Applied to Refugee and Ethnic Minority Populations with PTSD: Examples from "Culturally Adapted CBT"

    Hinton, Devon E.; Pich, Vuth; Hofmann, Stefan G.; Otto, Michael W.

    2013-01-01

    In this article we illustrate how we utilize acceptance and mindfulness techniques in our treatment (Culturally Adapted CBT, or CA-CBT) for traumatized refugees and ethnic minority populations. We present a Nodal Network Model (NNM) of Affect to explain the treatment's emphasis on body-centered mindfulness techniques and its focus on psychological…

  16. Optical Cluster-Finding with an Adaptive Matched-Filter Technique: Algorithm and Comparison with Simulations

    Dong, Feng; Pierpaoli, Elena; Gunn, James E.; Wechsler, Risa H.

    2007-10-29

    We present a modified adaptive matched filter algorithm designed to identify clusters of galaxies in wide-field imaging surveys such as the Sloan Digital Sky Survey. The cluster-finding technique is fully adaptive to imaging surveys with spectroscopic coverage, multicolor photometric redshifts, no redshift information at all, and any combination of these within one survey. It works with high efficiency in multi-band imaging surveys where photometric redshifts can be estimated with well-understood error distributions. Tests of the algorithm on realistic mock SDSS catalogs suggest that the detected sample is {approx} 85% complete and over 90% pure for clusters with masses above 1.0 x 10{sup 14}h{sup -1} M and redshifts up to z = 0.45. The errors of estimated cluster redshifts from maximum likelihood method are shown to be small (typically less that 0.01) over the whole redshift range with photometric redshift errors typical of those found in the Sloan survey. Inside the spherical radius corresponding to a galaxy overdensity of {Delta} = 200, we find the derived cluster richness {Lambda}{sub 200} a roughly linear indicator of its virial mass M{sub 200}, which well recovers the relation between total luminosity and cluster mass of the input simulation.

  17. Digital lock-in techniques for adaptive power-line interference extraction.

    Dobrev, Dobromir; Neycheva, Tatyana; Mudrov, Nikolay

    2008-07-01

    This paper presents a simple digital approach for adaptive power-line (PL) or other periodic interference extraction. By means of two digital square (or sine) wave mixers, the real and imaginary parts of the interference are found, and the interference waveform is synthesized and finally subtracted. The described technique can be implemented in an open-loop architecture where the interference is synthesized as a complex sinusoid or in a closed-loop architecture for automatic phase and gain control. The same approach can be used for removal of the fundamental frequency of the PL interference as well as its higher harmonics. It is suitable for real-time operation with popular low-cost microcontrollers. PMID:18560061

  18. Digraph description of k-interchange technique for optimization over permutations and adaptive algorithm system

    Levin, Mark Sh

    2011-01-01

    The paper describes a general glance to the use of element exchange techniques for optimization over permutations. A multi-level description of problems is proposed which is a fundamental to understand nature and complexity of optimization problems over permutations (e.g., ordering, scheduling, traveling salesman problem). The description is based on permutation neighborhoods of several kinds (e.g., by improvement of an objective function). Our proposed operational digraph and its kinds can be considered as a way to understand convexity and polynomial solvability for combinatorial optimization problems over permutations. Issues of an analysis of problems and a design of hierarchical heuristics are discussed. The discussion leads to a multi-level adaptive algorithm system which analyzes an individual problem and selects/designs a solving strategy (trajectory).

  19. Utilizing a Magnetic Abrasive Finishing Technique (MAF Via Adaptive Nero Fuzzy(ANFIS

    Amer A. Moosa

    2015-07-01

    Full Text Available An experimental study was conducted for measuring the quality of surface finishing roughness using magnetic abrasive finishing technique (MAF on brass plate which is very difficult to be polish by a conventional machining process where the cost is high and much more susceptible to surface damage as compared to other materials. Four operation parameters were studied, the gap between the work piece and the electromagnetic inductor, the current that generate the flux, the rotational Spindale speed and amount of abrasive powder size considering constant linear feed movement between machine head and workpiece. Adaptive Neuro fuzzy inference system (ANFIS was implemented for evaluation of a series of experiments and a verification with respect to specimen roughness change has been optimized and usefully achieved by obtained results were an average of the error between the surface roughness predicted by model simulation and that of direct measure is 2.0222 %.

  20. A Novel Implementation of RISI Controller Employing Adaptive Clock Gating Technique

    M.Kamaraju

    2011-11-01

    Full Text Available With the scaling of technology and the need for higher performance and more functionality power dissipation is becoming a major issue for controller design. Interrupt based programming is widely used for interfacing a processor with peripherals. The proposed architecture implements a mechanism which combines interrupt controller and RIS (Reduced Instruction Set CPU (Central processing unit on a single die. RISI Controller takes only one cycle for both interrupt request generation and acknowledgement. The architecture have a dynamic control unit which consists of a program flow controller, interrupt controller and I/O controller. Adaptive clock gating technique is used to reduce power consumption in the dynamic control unit. The controller consumes a power of 174µw@1MHz and is implemented in verilog HDL using Xilinx platform

  1. Modeling gravitational instabilities in self-gravitating protoplanetary disks with adaptive mesh refinement techniques

    Lichtenberg, Tim

    2015-01-01

    The astonishing diversity in the observed planetary population requires theoretical efforts and advances in planet formation theories. Numerical approaches provide a method to tackle the weaknesses of current planet formation models and are an important tool to close gaps in poorly constrained areas. We present a global disk setup to model the first stages of giant planet formation via gravitational instabilities (GI) in 3D with the block-structured adaptive mesh refinement (AMR) hydrodynamics code ENZO. With this setup, we explore the impact of AMR techniques on the fragmentation and clumping due to large-scale instabilities using different AMR configurations. Additionally, we seek to derive general resolution criteria for global simulations of self-gravitating disks of variable extent. We run a grid of simulations with varying AMR settings, including runs with a static grid for comparison, and study the effects of varying the disk radius. Adopting a marginally stable disk profile (Q_init=1), we validate the...

  2. Evaluation of internal adaptation of Class V resin composite restorations using three techniques of polymerization

    José Carlos Pereira

    2007-02-01

    Full Text Available OBJECTIVE: The purpose of this in vitro study was to evaluate the internal adaptation of Class V composite restorations to the cavity walls using three different techniques of polymerization. METHODS: Standard cavities were prepared on the buccal and lingual surfaces of 24 extracted human third molars with margins located above and below the cementoenamel junction. Restorations were placed in one increment using two restorative systems: 3M Filtek A110/ Single Bond (M and 3M Filtek Z250/ Single Bond (H in the same tooth, randomly in the buccal and lingual surfaces. Resin composites were polymerized using three techniques: Group 1 - Conventional (60 s - 600 mW/cm²; Group 2 - Soft-start (20 s - 200 mW/cm² , 40 s - 600 mW/cm²; Group 3 - Pulse Activation (3 s - 200 mW/cm², 3-min hiatus, 57 s - 600 mW/cm². Buccolingual sections were polished, impressions taken and replicated. Specimens were assessed under scanning electron microscopy up to X1000 magnification. Scores were given for presence or absence of gaps (0 - no gap; 1 - gap in one wall; 2 - gap in two walls; 3 - gap in three walls. RESULTS: The mean scores of the groups were (±SD were: G1M-3.0 (± 0.0; G2M-2.43 (± 0.8; G3M- 1.71 (± 0.9; G1H- 2.14 (± 1.2; G2H- 2.00 (± 0.8; G3H- 1.67 (± 1.1. Data were analyzed using Kruskal-Wallis and Dunnet's tests. No statistically significant difference (p>0.05 was found among groups. Gaps were observed in all groups. CONCLUSIONS: The photocuring technique and the type of resin composite had no influence on the internal adaptation of the material to the cavity walls. A positive effect was observed when the slow polymerization techniques were used.

  3. Determining appropriate timing of adaptive radiation therapy for nasopharyngeal carcinoma during intensity-modulated radiation therapy

    To determine appropriate timing of an adaptive radiation therapy (ART) replan by evaluating anatomic and dosimetric changes of target volumes and organs at risk (OARs) during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC). Nineteen NPC patients were recruited. Each patient had repeat computed tomography (CT) scans after each five fractions and at treatment completion. Automatic re-contouring the targets and OARs by using deformable registration algorithm was conducted through CT-CT fusion. Anatomic changes were assessed by comparing the initial CT and repeated CT. Hybrid plans with re-contouring were generated and the dose-volume histograms (DVH) of the hybrid plan and the original plan were compared. Progressive volume reductions in gross target volume for primary disease (GTVnx), gross target volume for involved lymph nodes (GTVnd), and parotids were observed over time. Comparing with the original plan, each hybrid plan had no significant difference in homogeneity index (HI) for all the targets. Some parameters for planning target volumes for primary disease and high-risk clinical target volume (PTVnx and PTV1, respectively) improved significantly, notably starting from the 10th fraction. These parameters included mean dose (Dmean), dose to 95 % of the volume (D95), percentage of the volume receiving 95 % of the prescription dose (V95), and conformity index (CI) for PTVnx, and Dmean, D95, and CI for PTV1. The dosimetric parameters for PTVnd remained the same in general except for D95 and V95 which had significant improvement at specific time points; whereas for PTV2, similar trend of dosimetric changes was also observed. Dose to some OARs increased significantly at some time points. There were significant anatomic and dosimetric changes in the targets and OARs. The target dose coverage in the hybrid plans did not get worse, but overdose occurred in some critical structures. Significant dosimetric changes should be considered as a

  4. Automatic IQ Imbalance Compensation Technique for Quadrature Modulator by Single-Tone Testing

    Kim, Minseok; Konishi, Yohei; Takada, Jun-Ichi; Gao, Boxin

    This letter proposes an automatic IQ imbalance compensation technique for quadrature modulators by means of spectrum measurement of RF signal using a spectrum analyzer. The analyzer feeds back only magnitude information of the frequency spectrum of the signal. To realize IQ imbalance compensation, the conventional method of steepest descent is modified; the descent direction is empirically determined and a variable step-size is introduced for accelerating convergence. The experimental results for a four-channel transmitter operating at 11GHz are presented for verification.

  5. Adaptive one-dimensional dimming technique for liquid crystal displays with low power consumption and high image quality

    Kim, Seung-Ryeol; Lee, Seung-Woo

    2015-07-01

    An adaptive one-dimensional (1-D) dimming technique for liquid crystal displays that compensates for nonuniform backlight distribution is proposed. Dimming techniques that do not consider luminance distribution may cause severe visual artifacts, such as a block artifact. However, an adaptive 1-D dimming technique that considers luminance distribution can reduce power consumption without causing any visual artifacts. Hardware implementation results verified that our method achieved lower power consumption compared to nondimming techniques and removed block artifacts from International Electrotechnical Commission 62087 standard images. The power consumption using the proposed method ranged from 85.5% to 94.7% compared to nondimming techniques. Furthermore, the contrast ratio increased by up to 231% and 165% on average compared to nondimming techniques.

  6. Robust breathing signal extraction from cone beam CT projections based on adaptive and global optimization techniques

    Chao, Ming; Wei, Jie; Li, Tianfang; Yuan, Yading; Rosenzweig, Kenneth E.; Lo, Yeh-Chi

    2016-04-01

    We present a study of extracting respiratory signals from cone beam computed tomography (CBCT) projections within the framework of the Amsterdam Shroud (AS) technique. Acquired prior to the radiotherapy treatment, CBCT projections were preprocessed for contrast enhancement by converting the original intensity images to attenuation images with which the AS image was created. An adaptive robust z-normalization filtering was applied to further augment the weak oscillating structures locally. From the enhanced AS image, the respiratory signal was extracted using a two-step optimization approach to effectively reveal the large-scale regularity of the breathing signals. CBCT projection images from five patients acquired with the Varian Onboard Imager on the Clinac iX System Linear Accelerator (Varian Medical Systems, Palo Alto, CA) were employed to assess the proposed technique. Stable breathing signals can be reliably extracted using the proposed algorithm. Reference waveforms obtained using an air bellows belt (Philips Medical Systems, Cleveland, OH) were exported and compared to those with the AS based signals. The average errors for the enrolled patients between the estimated breath per minute (bpm) and the reference waveform bpm can be as low as  -0.07 with the standard deviation 1.58. The new algorithm outperformed the original AS technique for all patients by 8.5% to 30%. The impact of gantry rotation on the breathing signal was assessed with data acquired with a Quasar phantom (Modus Medical Devices Inc., London, Canada) and found to be minimal on the signal frequency. The new technique developed in this work will provide a practical solution to rendering markerless breathing signal using the CBCT projections for thoracic and abdominal patients.

  7. Robust breathing signal extraction from cone beam CT projections based on adaptive and global optimization techniques.

    Chao, Ming; Wei, Jie; Li, Tianfang; Yuan, Yading; Rosenzweig, Kenneth E; Lo, Yeh-Chi

    2016-04-21

    We present a study of extracting respiratory signals from cone beam computed tomography (CBCT) projections within the framework of the Amsterdam Shroud (AS) technique. Acquired prior to the radiotherapy treatment, CBCT projections were preprocessed for contrast enhancement by converting the original intensity images to attenuation images with which the AS image was created. An adaptive robust z-normalization filtering was applied to further augment the weak oscillating structures locally. From the enhanced AS image, the respiratory signal was extracted using a two-step optimization approach to effectively reveal the large-scale regularity of the breathing signals. CBCT projection images from five patients acquired with the Varian Onboard Imager on the Clinac iX System Linear Accelerator (Varian Medical Systems, Palo Alto, CA) were employed to assess the proposed technique. Stable breathing signals can be reliably extracted using the proposed algorithm. Reference waveforms obtained using an air bellows belt (Philips Medical Systems, Cleveland, OH) were exported and compared to those with the AS based signals. The average errors for the enrolled patients between the estimated breath per minute (bpm) and the reference waveform bpm can be as low as -0.07 with the standard deviation 1.58. The new algorithm outperformed the original AS technique for all patients by 8.5% to 30%. The impact of gantry rotation on the breathing signal was assessed with data acquired with a Quasar phantom (Modus Medical Devices Inc., London, Canada) and found to be minimal on the signal frequency. The new technique developed in this work will provide a practical solution to rendering markerless breathing signal using the CBCT projections for thoracic and abdominal patients. PMID:27008349

  8. Dosimetric and Radiobiological Consequences of Computed Tomography–Guided Adaptive Strategies for Intensity Modulated Radiation Therapy of the Prostate

    Purpose: To examine a range of scenarios for image-guided adaptive radiation therapy of prostate cancer, including different schedules for megavoltage CT imaging, patient repositioning, and dose replanning. Methods and Materials: We simulated multifraction dose distributions with deformable registration using 35 sets of megavoltage CT scans of 13 patients. We computed cumulative dose–volume histograms, from which tumor control probabilities and normal tissue complication probabilities (NTCPs) for rectum were calculated. Five-field intensity modulated radiation therapy (IMRT) with 18-MV x-rays was planned to achieve an isocentric dose of 76 Gy to the clinical target volume (CTV). The differences between D95, tumor control probability, V70Gy, and NTCP for rectum, for accumulated versus planned dose distributions, were compared for different target volume sizes, margins, and adaptive strategies. Results: The CTV D95 for IMRT treatment plans, averaged over 13 patients, was 75.2 Gy. Using the largest CTV margins (10/7 mm), the D95 values accumulated over 35 fractions were within 2% of the planned value, regardless of the adaptive strategy used. For tighter margins (5 mm), the average D95 values dropped to approximately 73.0 Gy even with frequent repositioning, and daily replanning was necessary to correct this deficit. When personalized margins were applied to an adaptive CTV derived from the first 6 treatment fractions using the STAPLE (Simultaneous Truth and Performance Level Estimation) algorithm, target coverage could be maintained using a single replan 1 week into therapy. For all approaches, normal tissue parameters (rectum V70Gy and NTCP) remained within acceptable limits. Conclusions: The frequency of adaptive interventions depends on the size of the CTV combined with target margins used during IMRT optimization. The application of adaptive target margins (<5 mm) to an adaptive CTV determined 1 week into therapy minimizes the need for subsequent dose

  9. Intensity-modulated radiotherapy with simultaneous modulated accelerated boost technique and chemotherapy in patients with nasopharyngeal carcinoma

    To present our experience of intensity-modulated radiotherapy (IMRT) with simultaneous modulated accelerated radiotherapy (SMART) boost technique in patients with nasopharyngeal carcinoma (NPC). Sixty eight patients of NPC were treated between April 2006 and December 2011 including 45 males and 23 females with mean age of 46 (range 15–78). Stage distribution was; stage I 3, stage II 7, stage III 26 and stage IV 32. Among 45 (66.2%) evaluated patients for presence of Epstein-Barr virus (EBV), 40 (88.8%) were positive for EBV. Median radiation doses delivered to gross tumor volume (GTV) and positive neck nodes were 66–70 Gy, 63 Gy to clinical target volume (CTV) and 50.4 Gy to clinically negative neck. In addition 56 (82.4%) patients with bulky tumors (T4/N2+) received neoadjuvant chemotherapy 2–3 cycles (Cisplatin/Docetaxel or Cisplatin/Epirubicin or Cisplatin/5 Flourouracil). Concurrent chemotherapy with radiation was weekly Cisplatin 40 mg/m2 (40 patients) or Cisplatin 100 mg/m2 (28 patients). With a median follow up of 20 months (range 3–43), one patient developed local recurrence, two experienced regional recurrences and distant failure was seen in 3 patients. Estimated 3 year disease free survival (DFS) was 94%. Three year DFS for patients with EBV was 100% as compared to 60% without EBV (p = 0.0009). Three year DFS for patients with undifferentiated histology was 98% as compared to 82% with other histologies (p = 0.02). Acute grade 3 toxicity was seen as 21 (30.9%) having G-III mucositis and 6 (8.8%) with G-III skin reactions. Late toxicity was minimal and loss of taste was seen in 3 patients (7.5%) at time of analysis. IMRT with SMART in combination with chemotherapy is feasible and effective in terms of both the clinical response and safety profile. EBV, histopathology and nodal involvement were found important prognostic factors for locoregional recurrence

  10. Comparison of beam generation techniques using a phase only spatial light modulator.

    Clark, Thomas W; Offer, Rachel F; Franke-Arnold, Sonja; Arnold, Aidan S; Radwell, Neal

    2016-03-21

    Whether in art or for QR codes, images have proven to be both powerful and efficient carriers of information. Spatial light modulators allow an unprecedented level of control over the generation of optical fields by using digital holograms. There is no unique way of obtaining a desired light pattern however, leaving many competing methods for hologram generation. In this paper, we test six hologram generation techniques in the creation of a variety of modes as well as a photographic image: rating the methods according to obtained mode quality and power. All techniques compensate for a non-uniform mode profile of the input laser and incorporate amplitude scaling. We find that all methods perform well and stress the importance of appropriate spatial filtering. We expect these results to be of interest to those working in the contexts of microscopy, optical trapping or quantum image creation. PMID:27136818

  11. Mass Detection in Mammographic Images Using Wavelet Processing and Adaptive Threshold Technique.

    Vikhe, P S; Thool, V R

    2016-04-01

    Detection of mass in mammogram for early diagnosis of breast cancer is a significant assignment in the reduction of the mortality rate. However, in some cases, screening of mass is difficult task for radiologist, due to variation in contrast, fuzzy edges and noisy mammograms. Masses and micro-calcifications are the distinctive signs for diagnosis of breast cancer. This paper presents, a method for mass enhancement using piecewise linear operator in combination with wavelet processing from mammographic images. The method includes, artifact suppression and pectoral muscle removal based on morphological operations. Finally, mass segmentation for detection using adaptive threshold technique is carried out to separate the mass from background. The proposed method has been tested on 130 (45 + 85) images with 90.9 and 91 % True Positive Fraction (TPF) at 2.35 and 2.1 average False Positive Per Image(FP/I) from two different databases, namely Mammographic Image Analysis Society (MIAS) and Digital Database for Screening Mammography (DDSM). The obtained results show that, the proposed technique gives improved diagnosis in the early breast cancer detection. PMID:26811073

  12. Adaptive noise cancelling and time-frequency techniques for rail surface defect detection

    Liang, B.; Iwnicki, S.; Ball, A.; Young, A. E.

    2015-03-01

    Adaptive noise cancelling (ANC) is a technique which is very effective to remove additive noises from the contaminated signals. It has been widely used in the fields of telecommunication, radar and sonar signal processing. However it was seldom used for the surveillance and diagnosis of mechanical systems before late of 1990s. As a promising technique it has gradually been exploited for the purpose of condition monitoring and fault diagnosis. Time-frequency analysis is another useful tool for condition monitoring and fault diagnosis purpose as time-frequency analysis can keep both time and frequency information simultaneously. This paper presents an ANC and time-frequency application for railway wheel flat and rail surface defect detection. The experimental results from a scaled roller test rig show that this approach can significantly reduce unwanted interferences and extract the weak signals from strong background noises. The combination of ANC and time-frequency analysis may provide us one of useful tools for condition monitoring and fault diagnosis of railway vehicles.

  13. FPGA-based rate-adaptive LDPC-coded modulation for the next generation of optical communication systems.

    Zou, Ding; Djordjevic, Ivan B

    2016-09-01

    In this paper, we propose a rate-adaptive FEC scheme based on LDPC codes together with its software reconfigurable unified FPGA architecture. By FPGA emulation, we demonstrate that the proposed class of rate-adaptive LDPC codes based on shortening with an overhead from 25% to 42.9% provides a coding gain ranging from 13.08 dB to 14.28 dB at a post-FEC BER of 10-15 for BPSK transmission. In addition, the proposed rate-adaptive LDPC coding combined with higher-order modulations have been demonstrated including QPSK, 8-QAM, 16-QAM, 32-QAM, and 64-QAM, which covers a wide range of signal-to-noise ratios. Furthermore, we apply the unequal error protection by employing different LDPC codes on different bits in 16-QAM and 64-QAM, which results in additional 0.5dB gain compared to conventional LDPC coded modulation with the same code rate of corresponding LDPC code. PMID:27607718

  14. Unequal Protection of Video Streaming through Adaptive Modulation with a Trizone Buffer over Bluetooth Enhanced Data Rate

    Rouzbeh Razavi

    2007-12-01

    Full Text Available Bluetooth enhanced data rate wireless channel can support higher-quality video streams compared to previous versions of Bluetooth. Packet loss when transmitting compressed data has an effect on the delivered video quality that endures over multiple frames. To reduce the impact of radio frequency noise and interference, this paper proposes adaptive modulation based on content type at the video frame level and content importance at the macroblock level. Because the bit rate of protected data is reduced, the paper proposes buffer management to reduce the risk of buffer overflow. A trizone buffer is introduced, with a varying unequal protection policy in each zone. Application of this policy together with adaptive modulation results in up to 4 dB improvement in objective video quality compared to fixed rate scheme for an additive white Gaussian noise channel and around 10 dB for a Gilbert-Elliott channel. The paper also reports a consistent improvement in video quality over a scheme that adapts to channel conditions by varying the data rate without accounting for the video frame packet type or buffer congestion.

  15. Intensity modulation with the 'step and shoot' technique using a commercial MLC

    Purpose/Objective: For complex planning situations where organs at risk surrounding the target volume place stringent constraints, intensity-modulated treatments with photons provide a promising solution to improve tumor control and/or to reduce side effects. In order to evaluate the feasibility to implement intensity-modulated treatment techniques in clinical practice, a phantom experiment is performed to investigate the whole chain from the treatment design by the inverse-planning method to the delivery of the intensity-modulated beams using a commercial, computer-controlled MLC. Materials and Methods: A typical, clinically relevant case of a patient with a head and neck tumor (clivus chordoma) is selected. Using the inverse planning technique, optimized treatment plans are generated for 5 and 9 evenly distributed coplanar beams. An iterative gradient method is used to optimize a physical objective function that is based on the specified target dose and individual dose constraints assigned to each organ at risk (brain stem, eyes, optic nerves) by the radiation oncologist. The resulting intensity distributions of each beam are converted into MLC leaf position sequences using the discrete 'step and shoot' method and the dynamic sweep method followed by a discretization of the trajectories. Regions of underdosage due to the stairstep or wave shape design of the leaves ('tongue and groove') are avoided through synchronization of neighboring leaf pairs. The algorithm at the same time eliminates collision problems due to the special hardware restriction of MLCs that forbid adjacent opposing leaves to pass each other. The MLC leaf position files are transferred via computer link from the planning system to the linac console. The intensity-modulated fields are delivered using the Siemens MLC integrated in a Mevatron KD2 accelerator. The sequences are executed in the discrete 'step and shoot' technique using the autosequence mode of the linac that allows to step through

  16. Comparison of different automatic adaptive threshold selection techniques for estimating discharge from river width

    Elmi, Omid; Javad Tourian, Mohammad; Sneeuw, Nico

    2015-04-01

    The importance of river discharge monitoring is critical for e.g., water resource planning, climate change, hazard monitoring. River discharge has been measured at in situ gauges for more than a century. Despite various attempts, some basins are still ungauged. Moreover, a reduction in the number of worldwide gauging stations increases the interest to employ remote sensing data for river discharge monitoring. Finding an empirical relationship between simultaneous in situ measurements of discharge and river widths derived from satellite imagery has been introduced as a straightforward remote sensing alternative. Classifying water and land in an image is the primary task for defining the river width. Water appears dark in the near infrared and infrared bands in satellite images. As a result low values in the histogram usually represent the water content. In this way, applying a threshold on the image histogram and separating into two different classes is one of the most efficient techniques to build a water mask. Beside its simple definition, finding the appropriate threshold value in each image is the most critical issue. The threshold is variable due to changes in the water level, river extent, atmosphere, sunlight radiation, onboard calibration of the satellite over time. These complexities in water body classification are the main source of error in river width estimation. In this study, we are looking for the most efficient adaptive threshold algorithm to estimate the river discharge. To do this, all cloud free MODIS images coincident with the in situ measurement are collected. Next a number of automatic threshold selection techniques are employed to generate different dynamic water masks. Then, for each of them a separate empirical relationship between river widths and discharge measurements are determined. Through these empirical relationships, we estimate river discharge at the gauge and then validate our results against in situ measurements and also

  17. A dosimetric comparison of two-phase adaptive intensity-modulated radiotherapy for locally advanced nasopharyngeal cancer.

    Chitapanarux, Imjai; Chomprasert, Kittisak; Nobnaop, Wannapa; Wanwilairat, Somsak; Tharavichitkul, Ekasit; Jakrabhandu, Somvilai; Onchan, Wimrak; Traisathit, Patrinee; Van Gestel, Dirk

    2015-05-01

    The purpose of this investigation was to evaluate the potential dosimetric benefits of a two-phase adaptive intensity-modulated radiotherapy (IMRT) protocol for patients with locally advanced nasopharyngeal cancer (NPC). A total of 17 patients with locally advanced NPC treated with IMRT had a second computed tomography (CT) scan after 17 fractions in order to apply and continue the treatment with an adapted plan after 20 fractions. To simulate the situation without adaptation, a hybrid plan was generated by applying the optimization parameters of the original treatment plan to the anatomy of the second CT scan. The dose-volume histograms (DVHs) and dose statistics of the hybrid plan and the adapted plan were compared. The mean volume of the ipsilateral and contralateral parotid gland decreased by 6.1 cm(3) (30.5%) and 5.4 cm(3) (24.3%), respectively. Compared with the hybrid plan, the adapted plan provided a higher dose to the target volumes with better homogeneity, and a lower dose to the organs at risk (OARs). The Dmin of all planning target volumes (PTVs) increased. The Dmax of the spinal cord and brainstem were lower in 94% of the patients (1.6-5.9 Gy, P < 0.001 and 2.1-9.9 Gy, P < 0.001, respectively). The Dmean of the contralateral parotid decreased in 70% of the patients (range, 0.2-4.4 Gy). We could not find a relationship between dose variability and weight loss. Our two-phase adaptive IMRT protocol improves dosimetric results in terms of target volumes and OARs in patients with locally advanced NPC. PMID:25666189

  18. Cross-layer designed adaptive modulation algorithm with packet combining and truncated ARQ over MIMO Nakagami fading channels

    Aniba, Ghassane

    2011-04-01

    This paper presents an optimal adaptive modulation (AM) algorithm designed using a cross-layer approach which combines truncated automatic repeat request (ARQ) protocol and packet combining. Transmissions are performed over multiple-input multiple-output (MIMO) Nakagami fading channels, and retransmitted packets are not necessarily modulated using the same modulation format as in the initial transmission. Compared to traditional approach, cross-layer design based on the coupling across the physical and link layers, has proven to yield better performance in wireless communications. However, there is a lack for the performance analysis and evaluation of such design when the ARQ protocol is used in conjunction with packet combining. Indeed, previous works addressed the link layer performance of AM with truncated ARQ but without packet combining. In addition, previously proposed AM algorithms are not optimal and can provide poor performance when packet combining is implemented. Herein, we first show that the packet loss rate (PLR) resulting from the combining of packets modulated with different constellations can be well approximated by an exponential function. This model is then used in the design of an optimal AM algorithm for systems employing packet combining, truncated ARQ and MIMO antenna configurations, considering transmission over Nakagami fading channels. Numerical results are provided for operation with or without packet combining, and show the enhanced performance and efficiency of the proposed algorithm in comparison with existing ones. © 2011 IEEE.

  19. Use of a spatial light modulator as an adaptable phase mask for wavefront coding

    Carles, Guillem; Muyo, G; Bosch i Puig, Salvador; Harvey, A R

    2010-01-01

    A wavefront-coded imaging system employing a spatial light modulator (SLM) for the agile implementation of phase masks is presented. The SLM is a liquid crystal display that can be modulated to implement cubic phase masks of variable coding strength. These phase masks produce broad point spread functions insensitive to defocus aberration and are used in combination with post-detection digital image processing to extend the depth-of-field of an imaging system. A detailed description of the cal...

  20. Quadrature amplitude modulation from basics to adaptive trellis-coded turbo-equalised and space-time coded OFDM CDMA and MC-CDMA systems

    Hanzo, Lajos

    2004-01-01

    "Now fully revised and updated, with more than 300 pages of new material, this new edition presents the wide range of recent developments in the field and places particular emphasis on the family of coded modulation aided OFDM and CDMA schemes. In addition, it also includes a fully revised chapter on adaptive modulation and a new chapter characterizing the design trade-offs of adaptive modulation and space-time coding." "In summary, this volume amalgamates a comprehensive textbook with a deep research monograph on the topic of QAM, ensuring it has a wide-ranging appeal for both senior undergraduate and postgraduate students as well as practicing engineers and researchers."--Jacket.

  1. Frequency and Spatial Domains Adaptive-based Enhancement Technique for Thermal Infrared Images

    Debasis Chaudhuri

    2014-09-01

    Full Text Available Low contrast and noisy image limits the amount of information conveyed to the user. With the proliferation of digital imagery and computer interface between man-and-machine, it is now viable to consider digital enhancement in the image before presenting it to the user, thus increasing the information throughput. With better contrast, target detection and discrimination can be improved. The paper presents a sequence of filtering operations in frequency and spatial domains to improve the quality of the thermal infrared (IR images. Basically, two filters – homomorphic filter followed by adaptive Gaussian filter are applied to improve the quality of the thermal IR images. We have systematically evaluated the algorithm on a variety of images and carefully compared it with the techniques presented in the literature. We performed an evaluation of three filter banks such as homomorphic, Gaussian 5×5 and the proposed method, and we have seen that the proposed method yields optimal PSNR for all the thermal images. The results demonstrate that the proposed algorithm is efficient for enhancement of thermal IR images.Defence Science Journal, Vol. 64, No. 5, September 2014, pp.451-457, DOI:http://dx.doi.org/10.14429/dsj.64.6873

  2. Parametric Characterization of Porous 3D Bioscaffolds Fabricated by an Adaptive Foam Reticulation Technique

    Winnett, James; Mallick, Kajal K.

    2014-04-01

    Commercially pure titanium (Ti) and its alloys, in particular, titanium-vanadium-aluminium (Ti-6Al-4V), have been used as biomaterials due to their mechanical similarities to bone, good biocompatibility, and inertness in vivo. The introduction of porosity to the scaffolds leads to optimized mechanical properties and enhanced biological activity. The adaptive foam reticulation (AFR) technique has been previously used to generate hydroxyapatite bioscaffolds with enhanced cell behavior due to the generation of macroporous structures with microporous struts that provided routes for cell infiltration as well as attachment sites. Sacrificial polyurethane templates of 45 ppi and 90 ppi were coated in biomaterial-based slurries containing either Ti or Ti-6Al-4V as the biomaterial and camphene as the porogen. The resultant macropore sizes of 100-550 μm corresponded well with the initial template pore sizes while camphene produced micropores of 1-10 μm, with the level of microporosity related to the amount of porogen inclusion.

  3. Evaluation of Turbulence Models in Predicting Hypersonic and Subsonic Base Flows Using Grid Adaptation Techniques

    YOU Yancheng; BUANGA Bj(o)rn; HANNEMANN Volker; L(U)DEKE Heinrich

    2012-01-01

    The flows behind the base of a generic rocket,at both hypersonic and subsonic flow conditions,are numerically studied.The main concerns are addressed to the evaluation of turbulence models and the using of grid adaptation techniques.The investigation focuses on two configurations,related to hypersonic and subsonic experiments.The applicability tests of different turbulence models are conducted on the level of two-equation models calculating the steady state solution of the Reynolds-averaged Navier-Stokes(RANS) equations.All used models,the original Wilcox k-ω,the Menter shear-stress transport (SST) and the explicit algebraic Reynolds stress model(EARSM) formulation,predict an asymmetric base flow in both cases caused by the support of the models.A comparison with preliminary experimental results indicates a preference for the SST and EARSM results over the results from the older k-ω model.Sensitivity studies show no significant influence of the grid topology or the location of the laminar to turbulent transition on the base flow field,but a strong influence of even small angles of attack is reported from the related experiments.

  4. Tunable coherence-free microwave photonic bandpass filter based on double cross gain modulation technique.

    Chan, Erwin H W

    2012-10-01

    A tunable, coherence-free, high-resolution microwave photonic bandpass filter, which is compatible to be inserted in a conventional fiber optic link, is presented. It is based on using two cross gain modulation based wavelength converters in a recursive loop. The double cross gain modulation technique solves the semiconductor optical amplifier facet reflection problem in the conventional recursive structure; hence the new microwave photonic signal processor has no coherent interference and no phase-induced intensity noise. It allows arbitrary narrow-linewidth telecommunication-type lasers to be used while enabling stable filter operation to be realized. The filter passband frequency can be tuned by using a wavelength tunable laser and a wavelength dependent time delay component. Experimental results demonstrate robust high-resolution bandpass filter operation with narrow-linewidth sources, no phase-induced intensity noise and a high signal-to-noise ratio performance. Tunable coherence-free operation of the high-resolution bandpass filter is also demonstrated. PMID:23188262

  5. Modulating the Optoelectronic Properties of Silver Nanowires Films: Effect of Capping Agent and Deposition Technique

    D. Lopez-Diaz

    2015-11-01

    Full Text Available Silver nanowires 90 nm in diameter and 9 µm in length have been synthesized using different capping agents: polyvinyl pyrrolidone (PVP and alkyl thiol of different chain lengths. The nanowire structure is not influenced by the displacement of PVP by alkyl thiols, although alkyl thiols modify the lateral aggregation of nanowires. We examined the effect of the capping agent and the deposition method on the optical and electrical properties of films prepared by Spray and the Langmuir-Schaefer methodologies. Our results revealed that nanowires capped with PVP and C8-thiol present the best optoelectronic properties. By using different deposition techniques and by modifying the nanowire surface density, we can modulate the optoelectronic properties of films. This strategy allows obtaining films with the optoelectronic properties required to manufacture touch screens and electromagnetic shielding.

  6. A Novel Alamouti STBC Technique for MIMO System Using 16- QAM Modulation and Moving Average Filter

    Princy Pathak

    2014-08-01

    Full Text Available The wireless communication is the emerging field of research among communication researchers and they are continuously working towards the reduction if error occurred in the signal during transmission through wireless media. In this paper the wireless system is simulated with the application of Alamouti space time block codes (STBC with MIMO and MISO configurations to compare the results. The modulation technique used here is 16-QAM which is giving better results than other counterparts and to enhance the performance of the system i.e. to reduce the effect of errors on data we have applied a moving average filter(MAF. The performance of the system is shown with the simulation results with variable data sizes and found that the proposed approach is better for the system.

  7. Automatic online adaptive radiation therapy techniques for targets with significant shape change: a feasibility study

    Court, Laurence E; Tishler, Roy B; Petit, Joshua; Cormack, Robert; Chin Lee [Department of Radiation Oncology, Dana-Farber/Brigham and Women' s Hospital Cancer Center, 75 Francis Street, ASBI-L2, Boston, MA 02115 (United States)

    2006-05-21

    This work looks at the feasibility of an online adaptive radiation therapy concept that would detect the daily position and shape of the patient, and would then correct the daily treatment to account for any changes compared with planning position. In particular, it looks at the possibility of developing algorithms to correct for large complicated shape change. For co-planar beams, the dose in an axial plane is approximately associated with the positions of a single multi-leaf collimator (MLC) pair. We start with a primary plan, and automatically generate several secondary plans with gantry angles offset by regular increments. MLC sequences for each plan are calculated keeping monitor units (MUs) and number of segments constant for a given beam (fluences are different). Bulk registration (3D) of planning and daily CT images gives global shifts. Slice-by-slice (2D) registration gives local shifts and rotations about the longitudinal axis for each axial slice. The daily MLC sequence is then created for each axial slice/MLC leaf pair combination, by taking the MLC positions from the pre-calculated plan with the nearest rotation, and shifting using a beam's-eye-view calculation to account for local linear shifts. A planning study was carried out using two head and neck region MR images of a healthy volunteer which were contoured to simulate a base-of-tongue treatment: one with the head straight (used to simulate the planning image) and the other with the head tilted to the left (the daily image). Head and neck treatment was chosen to evaluate this technique because of its challenging nature, with varying internal and external contours, and multiple degrees of freedom. Shape change was significant: on a slice-by-slice basis, local rotations in the daily image varied from 2 to 31 deg, and local shifts ranged from -0.2 to 0.5 cm and -0.4 to 0.0 cm in right-left and posterior-anterior directions, respectively. The adapted treatment gave reasonable target coverage (100

  8. The adaptive immune system restrains Alzheimer's disease pathogenesis by modulating microglial function.

    Marsh, Samuel E; Abud, Edsel M; Lakatos, Anita; Karimzadeh, Alborz; Yeung, Stephen T; Davtyan, Hayk; Fote, Gianna M; Lau, Lydia; Weinger, Jason G; Lane, Thomas E; Inlay, Matthew A; Poon, Wayne W; Blurton-Jones, Mathew

    2016-03-01

    The innate immune system is strongly implicated in the pathogenesis of Alzheimer's disease (AD). In contrast, the role of adaptive immunity in AD remains largely unknown. However, numerous clinical trials are testing vaccination strategies for AD, suggesting that T and B cells play a pivotal role in this disease. To test the hypothesis that adaptive immunity influences AD pathogenesis, we generated an immune-deficient AD mouse model that lacks T, B, and natural killer (NK) cells. The resulting "Rag-5xfAD" mice exhibit a greater than twofold increase in β-amyloid (Aβ) pathology. Gene expression analysis of the brain implicates altered innate and adaptive immune pathways, including changes in cytokine/chemokine signaling and decreased Ig-mediated processes. Neuroinflammation is also greatly exacerbated in Rag-5xfAD mice as indicated by a shift in microglial phenotype, increased cytokine production, and reduced phagocytic capacity. In contrast, immune-intact 5xfAD mice exhibit elevated levels of nonamyloid reactive IgGs in association with microglia, and treatment of Rag-5xfAD mice or microglial cells with preimmune IgG enhances Aβ clearance. Last, we performed bone marrow transplantation studies in Rag-5xfAD mice, revealing that replacement of these missing adaptive immune populations can dramatically reduce AD pathology. Taken together, these data strongly suggest that adaptive immune cell populations play an important role in restraining AD pathology. In contrast, depletion of B cells and their appropriate activation by T cells leads to a loss of adaptive-innate immunity cross talk and accelerated disease progression. PMID:26884167

  9. A practical application and implementation of adaptive techniques using neural networks in autoreclose protection and system control

    Gardiner, I.P.

    1997-12-31

    Reyrolle Protection have carried out research in conjunction with Bath University into applying adaptive techniques to autoreclose schemes and have produced an algorithm based on an artificial neural network which can recognise when it is ``safe to reclose`` and when it is ``unsafe to reclose``. This algorithm is based on examination of the induced voltage on the faulted phase and by applying pattern recognition techniques determines when the secondary arc extinguishes. Significant operational advantages can now be realised using this technology resulting in changes to existing operational philosophy. Conventional autoreclose relays applied to the system have followed the philosophy of ``reclose to restore the system``, but a progression from this philosophy to ``reclose only if safe to do so`` can now be made using this adaptive approach. With this adaptive technique the main requirement remains to protect the investment i.e. the system, by reducing damaging shocks and voltage dips and maintaining continuity of supply. The adaptive technique can be incorporated into a variety of schemes which will act to further this goal in comparison with conventional autoreclose. (Author)

  10. The efficiency of Lutz, Kato-Katz and Baermann-Moraes (adapted techniques association to the diagnosis of intestinal helmints

    Henry Percy Willcox

    1991-12-01

    Full Text Available The association of Lutz/Kato-Katz and Lutz/Bermann-Moraes (adapted techniques was used to improve better results that ranged from 0.4 to 11 times in the search of eggs of Ascaris lumbricoides, Schistosoma mansoni, Trichiuris trichiura, Taenia sp. and larvae of Strongyloides stercoralis.

  11. Aquifer Storage and Recovery as a Viable Climate Change Adaptation Technique: Sustainable Development under the Current Regulatory Framework

    A holistic investigation of aquifer storage and recovery (ASR) technique and application in the U.S. is being conducted as a part of the USEPA Water Resources Adaptation Program (WRAP). The research focus is to evaluate the potential of ASR application as a practical climate chan...

  12. Intelligent Adaptation and Personalization Techniques in Computer-Supported Collaborative Learning

    Demetriadis, Stavros; Xhafa, Fatos

    2012-01-01

    Adaptation and personalization have been extensively studied in CSCL research community aiming to design intelligent systems that adaptively support eLearning processes and collaboration. Yet, with the fast development in Internet technologies, especially with the emergence of new data technologies and the mobile technologies, new opportunities and perspectives are opened for advanced adaptive and personalized systems. Adaptation and personalization are posing new research and development challenges to nowadays CSCL systems. In particular, adaptation should be focused in a multi-dimensional way (cognitive, technological, context-aware and personal). Moreover, it should address the particularities of both individual learners and group collaboration. As a consequence, the aim of this book is twofold. On the one hand, it discusses the latest advances and findings in the area of intelligent adaptive and personalized learning systems. On the other hand it analyzes the new implementation perspectives for intelligen...

  13. Swarming Speed Control for DC Permanent Magnet Motor Drive via Pulse Width Modulation Technique and DC/DC Converter

    A.S. Oshaba; E.S. Ali

    2013-01-01

    This study presents an approach for the speed control of a permanent magnet DC motor drive via Pulse Width Modulation (PWM) technique and a DC/DC converter. The Particle Swarm Optimization (PSO) technique is used to minimize a time domain objective function and obtain the optimal controller parameters. The performance of the proposed technique has been evaluated using various types of disturbances including load torque variations. Simulation results illustrate clearly the robustness of the co...

  14. Simulation verification techniques study. Task report 4: Simulation module performance parameters and performance standards

    1974-01-01

    Shuttle simulation software modules in the environment, crew station, vehicle configuration and vehicle dynamics categories are discussed. For each software module covered, a description of the module functions and operational modes, its interfaces with other modules, its stored data, inputs, performance parameters and critical performance parameters is given. Reference data sources which provide standards of performance are identified for each module. Performance verification methods are also discussed briefly.

  15. Potentiating mGluR5 Function with a Positive Allosteric Modulator Enhances Adaptive Learning

    Xu, Jian; Zhu, Yongling; Kraniotis, Stephen; He, Qionger; Marshall, John J.; Nomura, Toshihiro; Stauffer, Shaun R.; Lindsley, Craig W.; Conn, P. Jeffrey; Contractor, Anis

    2013-01-01

    Metabotropic glutamate receptor 5 (mGluR5) plays important roles in modulating neural activity and plasticity and has been associated with several neuropathological disorders. Previous work has shown that genetic ablation or pharmacological inhibition of mGluR5 disrupts fear extinction and spatial reversal learning, suggesting that mGluR5…

  16. The adaptive immune system restrains Alzheimer’s disease pathogenesis by modulating microglial function

    Abud, Edsel M.; Lakatos, Anita; Karimzadeh, Alborz; Yeung, Stephen T.; Davtyan, Hayk; Fote, Gianna M.; Lau, Lydia; Weinger, Jason G.; Lane, Thomas E.; Inlay, Matthew A.; Poon, Wayne W.; Blurton-Jones, Mathew

    2016-01-01

    The innate immune system is strongly implicated in the pathogenesis of Alzheimer’s disease (AD). In contrast, the role of adaptive immunity in AD remains largely unknown. However, numerous clinical trials are testing vaccination strategies for AD, suggesting that T and B cells play a pivotal role in this disease. To test the hypothesis that adaptive immunity influences AD pathogenesis, we generated an immune-deficient AD mouse model that lacks T, B, and natural killer (NK) cells. The resulting “Rag-5xfAD” mice exhibit a greater than twofold increase in β-amyloid (Aβ) pathology. Gene expression analysis of the brain implicates altered innate and adaptive immune pathways, including changes in cytokine/chemokine signaling and decreased Ig-mediated processes. Neuroinflammation is also greatly exacerbated in Rag-5xfAD mice as indicated by a shift in microglial phenotype, increased cytokine production, and reduced phagocytic capacity. In contrast, immune-intact 5xfAD mice exhibit elevated levels of nonamyloid reactive IgGs in association with microglia, and treatment of Rag-5xfAD mice or microglial cells with preimmune IgG enhances Aβ clearance. Last, we performed bone marrow transplantation studies in Rag-5xfAD mice, revealing that replacement of these missing adaptive immune populations can dramatically reduce AD pathology. Taken together, these data strongly suggest that adaptive immune cell populations play an important role in restraining AD pathology. In contrast, depletion of B cells and their appropriate activation by T cells leads to a loss of adaptive–innate immunity cross talk and accelerated disease progression. PMID:26884167

  17. Dosimetric comparison between jaw tracking and static jaw techniques in intensity-modulated radiotherapy

    To compare the dosimetric differences between jaw tracking technique (JTT) and static jaw technique (SJT) in dynamic intensity-modulated radiotherapy (d-IMRT) and assess the potential advantages of jaw tracking technique. Two techniques, jaw tracking and static jaw, were used respectively to develop the d-IMRT plans for 28 cancer patients with various lesion sites: head and neck, lungs, esophageal, abdominal, prostate, rectal and cervical. The dose volume histograms (DVH) and selected dosimetric indexes for the whole body and for organs at risk (OARs) were compared. A two dimensional ionization chamber Array Seven29 (PTW, Freiburg, Germany) and OCTAVIUS Octagonal phantom (PTW, Freiburg, Germany) were used to verify all the plans. For all patients, the treatment plans using both techniques met the clinical requirements. The V5, V10, V20, V30, V40 (volumes receiving 5, 10, 20, 30 and 40 Gy at least, respectively), mean dose (Dmean) for the whole body and V5, V10, V20, Dmean for lungs in the JTT d-IMRT plans were significantly less than the corresponding values of the SJT d-IMRT plans (p < 0.001). The JTT d-IMRT plans deposited lower maximum dose (Dmax) to the lens, eyes, brainstem, spinal cord, and right optic nerve, the doses reductions for these OARs ranged from 2.2% to 28.6%. The JTT d-IMRT plans deposited significantly lower Dmean to various OARs (all p values < 0.05), the mean doses reductions for these OARs ranged from 1.1% to 31.0%, and the value reductions depend on the volume and the location of the OARs. The γ evaluation method showed an excellent agreement between calculation and measurement for all techniques with criteria of 3%/3 mm. Both jaw tracking and static jaw d-IMRT plans can achieve comparable target dose coverage. JTT displays superior OARs sparing than SJT plans. These results are of clinical importance, especially for the patients with large and complex targets but close to some highly radio-sensitive organs to spare, and for patients with

  18. An Innovations-Based Noise Cancelling Technique on Inverse Kepstrum Whitening Filter and Adaptive FIR Filter in Beamforming Structure

    Jinsoo Jeong

    2011-06-01

    Full Text Available This paper presents an acoustic noise cancelling technique using an inverse kepstrum system as an innovations-based whitening application for an adaptive finite impulse response (FIR filter in beamforming structure. The inverse kepstrum method uses an innovations-whitened form from one acoustic path transfer function between a reference microphone sensor and a noise source so that the rear-end reference signal will then be a whitened sequence to a cascaded adaptive FIR filter in the beamforming structure. By using an inverse kepstrum filter as a whitening filter with the use of a delay filter, the cascaded adaptive FIR filter estimates only the numerator of the polynomial part from the ratio of overall combined transfer functions. The test results have shown that the adaptive FIR filter is more effective in beamforming structure than an adaptive noise cancelling (ANC structure in terms of signal distortion in the desired signal and noise reduction in noise with nonminimum phase components. In addition, the inverse kepstrum method shows almost the same convergence level in estimate of noise statistics with the use of a smaller amount of adaptive FIR filter weights than the kepstrum method, hence it could provide better computational simplicity in processing. Furthermore, the rear-end inverse kepstrum method in beamforming structure has shown less signal distortion in the desired signal than the front-end kepstrum method and the front-end inverse kepstrum method in beamforming structure.

  19. Systematic analysis of the kalimantacin assembly line NRPS module using an adapted targeted mutagenesis approach.

    Uytterhoeven, Birgit; Appermans, Kenny; Song, Lijiang; Masschelein, Joleen; Lathouwers, Thomas; Michiels, Chris W; Lavigne, Rob

    2016-04-01

    Kalimantacin is an antimicrobial compound with strong antistaphylococcal activity that is produced by a hybrid trans-acyltransferase polyketide synthase/nonribosomal peptide synthetase system in Pseudomonas fluorescens BCCM_ID9359. We here present a systematic analysis of the substrate specificity of the glycine-incorporating adenylation domain from the kalimantacin biosynthetic assembly line by a targeted mutagenesis approach. The specificity-conferring code was adapted for use in Pseudomonas and mutated adenylation domain active site sequences were introduced in the kalimantacin gene cluster, using a newly adapted ligation independent cloning method. Antimicrobial activity screens and LC-MS analyses revealed that the production of the kalimantacin analogues in the mutated strains was abolished. These results support the idea that further insight in the specificity of downstream domains in nonribosomal peptide synthetases and polyketide synthases is required to efficiently engineer these strains in vivo. PMID:26666990

  20. Streptococcus agalactiae adapts to glucose stress conditions by modulating gene expression profile

    Di Palo, Benedetta

    2012-01-01

    Diabetes mellitus is considered a risk factor for Group B Streptococcus (GBS) infections. Typically, this pathology is associated to high glucose levels in the bloodstream. Although clinical evidences support this notion, the physiological mechanisms underlying GBS adaptation to such conditions are not yet defined. In the attempt to address this issue, we performed comparative global gene expression analysis of GBS grown under glucose-stress conditions and observed that a number of metabolic ...

  1. Adaptive times : modulating time perception in neglect patients and healthy individuals

    Kardinal, Mareike

    2014-01-01

    Are time and space linked in the brain? Over the past decades, there have been increasing indications for a spatial representation of time intervals. They come from time-space interference phenomena in healthy individuals and from observation of time deficits in patients with spatial neglect. While there are well-established treatment possibilities for visuospatial distortions in these patients, only few studies have examined time deficits and their possible modulation. If time and space proc...

  2. Test techniques: A survey paper on cryogenic tunnels, adaptive wall test sections, and magnetic suspension and balance systems

    Kilgore, Robert A.; Dress, David A.; Wolf, Stephen W. D.; Britcher, Colin P.

    1989-01-01

    The ability to get good experimental data in wind tunnels is often compromised by things seemingly beyond our control. Inadequate Reynolds number, wall interference, and support interference are three of the major problems in wind tunnel testing. Techniques for solving these problems are available. Cryogenic wind tunnels solve the problem of low Reynolds number. Adaptive wall test sections can go a long way toward eliminating wall interference. A magnetic suspension and balance system (MSBS) completely eliminates support interference. Cryogenic tunnels, adaptive wall test sections, and MSBS are surveyed. A brief historical overview is given and the present state of development and application in each area is described.

  3. Development and Evaluation of Multiple Isocentric Volumetric Modulated Arc Therapy Technique for Craniospinal Axis Radiotherapy Planning

    Purpose: To develop and compare a volumetric modulated arc therapy (VMAT) technique with conventional radiotherapy for craniospinal irradiation with respect to improved dose conformity and homogeneity in the planning target volume (PTV) and to reduced dose to organs at risk (OAR). Methods and Materials: Conventional craniospinal axis radiotherapy plans of 5 patients were acquired. The median (range) length of the PTV was 58.9 (48.1–83.7) cm. The 6-MV VMAT plans were inversely planned with one isocenter near the base of the brain and the minimum number of isocenters required for the specified lengths of spine. The plans were optimized with high weighting for PTV coverage and low weighting for OAR sparing. Conformity and heterogeneity indices, dose–volume histograms, mean doses, and non-PTV integral doses from the two plans (prescription dose 23.4 Gy in 13 fractions) were compared. Results: The median (range) conformity index of VMAT was 1.22 (1.09–1.45), compared with 1.69 (1.44–2.67) for conventional plans (p = 0.04). The median (range) heterogeneity index was also lower for VMAT compared with conventional plans: 1.04 (1.03–1.07) vs. 1.12 (1.09–1.19), respectively (p = 0.04). A significant reduction of mean and maximum doses was observed in the heart, thyroid, esophagus, optic nerves, and eyes with VMAT when compared with conventional plans. A decrease in body V10Gy was observed, but for 4 of 5 patients non-PTV integral dose was increased with VMAT when compared with the conventional plans. Conclusions: A VMAT technique to treat the craniospinal axis significantly reduces OAR dose, potentially leading to lower late organ toxicity. However, this is achieved at the expense of increased low-dose volumes, which is inherent to the technique, carrying a potentially increased risk of secondary malignancies.

  4. Non-invasive near-field measurement setup based on modulated scatterer technique applied to microwave tomography

    Memarzadeh-Tehran, Hamidreza

    The main focus of this thesis is to address the design and development of a near-field (NF) imaging setup based on the modulated scatterer technique (MST). MST is a well-known approach used in applications where accurate and perturbation-free measurement results are necessary. Of the possible implementations available for making an MST probe, including electrical, optical and mechanical, the optically modulated scatterer OMS was considered in order to provide nearly perturbation-free measurement due to the invisibility of optical fiber to the radio-frequency electromagnetic fields. The OMS probe consists of a commercial, off-the-shelf (COTS) photodiode chip (nonlinear device), a short-dipole antenna acting as a scatterer and a matching network (passive circuit). The latter improves the scattering properties and also increases the sensitivity of the OMS probe within the frequency range in which the matching network is optimized. The radiation characteristics of the probe, including cross-polarization response and omnidirectional sensitivity, were both theoretically and experimentally investigated. Finally, the performance and reliability of the probe was studied by comparing measured near-field distributions on a known field distribution with simulations. Increased imaging speed was obtained using an array of OMS probes, which reduces mechanical movements. Mutual-coupling, switching time and shadowing effect, which all may affect the performance of the array, were investigated. Then, the results obtained by the array were validated in a NF imager by measuring the E-field distribution of an antenna under test (AUT) and comparing it with a simulation. Calibration and data averaging were applied to raw data to compensate the probes for uncertainties in fabrication and interaction between array/AUT and array/receiving antenna. Dynamic range and linearity of the developed NF imager was improved by adding a carrier canceller circuit to the front-end of the receiver. The

  5. Swarming Speed Control for DC Permanent Magnet Motor Drive via Pulse Width Modulation Technique and DC/DC Converter

    A.S. Oshaba

    2013-05-01

    Full Text Available This study presents an approach for the speed control of a permanent magnet DC motor drive via Pulse Width Modulation (PWM technique and a DC/DC converter. The Particle Swarm Optimization (PSO technique is used to minimize a time domain objective function and obtain the optimal controller parameters. The performance of the proposed technique has been evaluated using various types of disturbances including load torque variations. Simulation results illustrate clearly the robustness of the controller and validity of the design technique for controlling the speed of permanent magnet motors.

  6. An Adaptive Clutter Suppression Technique for Moving Target Detector in Pulse Doppler Radar

    A. Mandal

    2014-04-01

    Full Text Available An adaptive system performs the processing by using an architecture having time-varying parameters on the received signals which accompanies with clutters. In this paper, an adaptive moving target detector has been designed to meet the challenges of target detection amidst various levels of clutter environments. The approach has been used that is able to overcome the inherent limitations of conventional systems (e.g. Moving Target Indicator, Fast Fourier Transform etc. having predefined coefficients. In this purpose an optimal design of transversal filter is being proposed along with various weight selection Maps to improve probability of detection in ground based surveillance radar. A modified LMS algorithm based adaptive FIR filter has been implemented utilizing modular CORDIC unit as a main processing element for filtering as well as weight updatation to suppress clutter of various intensity. Extensive MATLAB simulations have been done using various levels of clutter input to show the effectiveness of adaptive moving target detector (AMTD.

  7. ADAPTING E-COURSES USING DATA MINING TECHNIQUES - PDCA APPROACH AND QUALITY SPIRAL

    Marija Blagojevic; Zivadin Micic

    2013-01-01

    This paper presents an approach to adapting e-courses based on original PDCA (Plan, Do, Check , Act) platform and quality spiral. An algorithm for the adaptation of e-courses was proposed and implemented into the Moodle Learning Management System at the Faculty of Technical Sciences, Cacak. The approach is primarily based on improving LMS (Learning Management Systems) or e-learning systems through modifying the electronic structure of the courses by predicting the behaviour patterns of the us...

  8. Robust Steering Vector Mismatch Techniques for Reduced Rank Adaptive Array Signal Processing

    Nguyen, Hien

    2002-01-01

    The research presented in this dissertation is on the development of advanced reduced rank adaptive signal processing for airborne radar space-time adaptive processing (STAP) and steering vector mismatch robustness. This is an important area of research in the field of airborne radar signal processing since practical STAP algorithms should be robust against various kinds of mismatch errors. The clutter return in an airborne radar has widely spread Doppler frequencies; therefore STAP, a two-di...

  9. Antenna subset selection at multi-antenna relay with adaptive modulation

    Choi, Seyeong

    2011-06-01

    In this paper, we proposed several antenna selection schemes for cooperative diversity systems with adaptive transmission. The proposed schemes were based on dual-hop relaying where a relay with multiple-antenna capabilities at reception and transmission is deployed between the source and the destination nodes. We analyzed the performance of the proposed schemes by quantifying the average spectral efficiency and the outage probability. We also investigated the trade-off of performance and complexity by comparing the average number of active antennas, path estimations, and signal-to-noise ratio comparisons of the different proposed schemes. Copyright © 2011 John Wiley & Sons, Ltd.

  10. Wavefront response matrix for closed-loop adaptive optics system based on non-modulation pyramid wavefront sensor

    Wang, Jianxin; Bai, Fuzhong; Ning, Yu; Li, Fei; Jiang, Wenhan

    2012-06-01

    Pyramid wavefront sensor (PWFS) is a kind of wavefront sensor with high spatial resolution and high energy utilization. In this paper an adaptive optics system with PWFS as wavefront sensor and liquid-crystal spatial light modulator (LC-SLM) as wavefront corrector is built in the laboratory. The wavefront response matrix is a key element in the close-loop operation. It can be obtained by measuring the real response to given aberrations, which is easily contaminated by noise and influenced by the inherent aberration in the optical system. A kind of analytic solution of response matrix is proposed, with which numerical simulation and experiment are also implemented to verify the performance of closed-loop correction of static aberration based on linear reconstruction theory. Results show that this AO system with the proposed matrix can work steadily in closed-loop operation.

  11. Performance analysis of two-way amplify and forward relaying with adaptive modulation over multiple relay network

    Hwang, Kyusung

    2011-02-01

    In this letter, we propose two-way amplify-and-forward relaying in conjunction with adaptive modulation in order to improve spectral efficiency of relayed communication systems while monitoring the required error performance. We also consider a multiple relay network where only the best relay node is utilized so that the diversity order increases while maintaining a low complexity of implementation as the number of relays increases. Based on the best relay selection criterion, we offer an upper bound on the signal-to-noise ratio to keep the performance analysis tractable. Our numerical examples show that the proposed system offers a considerable gain in spectral efficiency while satisfying the error rate requirements. © 2011 IEEE.

  12. Adaptive antenna system for OFDMA WiMAX radio-over-fiber links using a directly modulated R-SOA and optical filtering

    Presi, Marco; Prince, Kamau; Chiuchiarelli, Andrea;

    2009-01-01

    We implement an adaptive beam steering system based on a directly-modulated unseeded reflective SOA. this system allows the distribution of 2.4 GHz 64-QAM OFDMA signals with 2048-subcarriers (72 Mb/s) satisfying the IEEE 802.16e specifications......We implement an adaptive beam steering system based on a directly-modulated unseeded reflective SOA. this system allows the distribution of 2.4 GHz 64-QAM OFDMA signals with 2048-subcarriers (72 Mb/s) satisfying the IEEE 802.16e specifications...

  13. ADAPTATION OF CRACK GROWTH DETECTION TECHNIQUES TO US MATERIAL TEST REACTORS

    A. Joseph Palmer; Sebastien P. Teysseyre; Kurt L. Davis; Gordon Kohse; Yakov Ostrovsky; David M. Carpenter; Joy L. Rempe

    2015-04-01

    A key component in evaluating the ability of Light Water Reactors to operate beyond 60 years is characterizing the degradation of materials exposed to radiation and various water chemistries. Of particular concern is the response of reactor materials to Irradiation Assisted Stress Corrosion Cracking (IASCC). Some test reactors outside the United States, such as the Halden Boiling Water Reactor (HBWR), have developed techniques to measure crack growth propagation during irradiation. The basic approach is to use a custom-designed compact loading mechanism to stress the specimen during irradiation, while the crack in the specimen is monitored in-situ using the Direct Current Potential Drop (DCPD) method. In 2012 the US Department of Energy commissioned the Idaho National Laboratory and the MIT Nuclear Reactor Laboratory (MIT NRL) to take the basic concepts developed at the HBWR and adapt them to a test rig capable of conducting in-pile IASCC tests in US Material Test Reactors. The first two and half years of the project consisted of designing and testing the loader mechanism, testing individual components of the in-pile rig and electronic support equipment, and autoclave testing of the rig design prior to insertion in the MIT Reactor. The load was applied to the specimen by means of a scissor like mechanism, actuated by a miniature metal bellows driven by pneumatic pressure and sized to fit within the small in-core irradiation volume. In addition to the loader design, technical challenges included developing robust connections to the specimen for the applied current and voltage measurements, appropriate ceramic insulating materials that can endure the LWR environment, dealing with the high electromagnetic noise environment of a reactor core at full power, and accommodating material property changes in the specimen, due primarily to fast neutron damage, which change the specimen resistance without additional crack growth. The project culminated with an in

  14. Impact of adaptive proactive reconfiguration technique on Vmin and lifetime of SRAM caches

    Pouyan, Peyman; Amat Bertran, Esteve; Barajas Ojeda, Enrique; Rubio Sola, Jose Antonio

    2014-01-01

    This work presents a test and measurement technique to monitor aging and process variation status of SRAM cells as an aging-aware design technique. We have then verified our technique with an implemented chip. The obtained aging information are utilized to guide our proactive strategies, and to track the impact of aging in new reconfiguration techniques for cache memory structures. Our proactive techniques improve the reliability, extend the SRAMs lifetime, and reduce the Vmin drift in presen...

  15. Joint multiuser switched diversity and adaptive modulation schemes for spectrum sharing systems

    Qaraqe, Marwa

    2012-12-01

    In this paper, we develop multiuser access schemes for spectrum sharing systems whereby secondary users are allowed to share the spectrum with primary users under the condition that the interference observed at the primary receiver is below a predetermined threshold. In particular, we devise two schemes for selecting a user among those that satisfy the interference constraint and achieve an acceptable signal-to-noise ratio level. The first scheme selects the user that reports the best channel quality. In order to alleviate the high feedback load associated with the first scheme, we develop a second scheme based on the concept of switched diversity where the base station scans the users in a sequential manner until an acceptable user is found. In addition to these two selection schemes, we consider two power adaptive settings at the secondary users based on the amount of interference available at the secondary transmitter. In the On/Off power setting, users are allowed to transmit based on whether the interference constraint is met or not, while in the full power adaptive setting, the users are allowed to vary their transmission power to satisfy the interference constraint. Finally, we present numerical results for our proposed algorithms where we show the trade-off between the average spectral efficiency and average feedback load for both schemes. © 2012 IEEE.

  16. Forecasting the Cell Temperature of PV Modules with an Adaptive System

    Giuseppina Ciulla

    2013-01-01

    Full Text Available The need to reduce energy consumptions and to optimize the processes of energy production has pushed the technology towards the implementation of hybrid systems for combined production of electric and thermal energies. In particular, recent researches look with interest at the installation of hybrid system PV/T. To improve the energy performance of these systems, it is necessary to know the operating temperature of the photovoltaic modules. The determination of the operating temperature is a key parameter for the assessment of the actual performance of photovoltaic panels. In the literature, it is possible to find different correlations that evaluate the referring to standard test conditions and/or applying some theoretical simplifications/assumptions. Nevertheless, the application of these different correlations, for the same conditions, does not lead to unequivocal results. In this work an alternative method, based on the employment of artificial neural networks (ANNs, was proposed to predict the operating temperature of a PV module. This methodology does not require any simplification or physical assumptions. In the paper is described the ANN that obtained the best performance: a multilayer perception network. The results have been compared with experimental monitored data and with some of the most cited empirical correlations proposed by different authors.

  17. Adaptive gain modulation in V1 explains contextual modifications during bisection learning.

    Roland Schäfer

    2009-12-01

    Full Text Available The neuronal processing of visual stimuli in primary visual cortex (V1 can be modified by perceptual training. Training in bisection discrimination, for instance, changes the contextual interactions in V1 elicited by parallel lines. Before training, two parallel lines inhibit their individual V1-responses. After bisection training, inhibition turns into non-symmetric excitation while performing the bisection task. Yet, the receptive field of the V1 neurons evaluated by a single line does not change during task performance. We present a model of recurrent processing in V1 where the neuronal gain can be modulated by a global attentional signal. Perceptual learning mainly consists in strengthening this attentional signal, leading to a more effective gain modulation. The model reproduces both the psychophysical results on bisection learning and the modified contextual interactions observed in V1 during task performance. It makes several predictions, for instance that imagery training should improve the performance, or that a slight stimulus wiggling can strongly affect the representation in V1 while performing the task. We conclude that strengthening a top-down induced gain increase can explain perceptual learning, and that this top-down signal can modify lateral interactions within V1, without significantly changing the classical receptive field of V1 neurons.

  18. Two-dimensional modulation technique with dc voltage control for single-phase two-cell cascaded converters

    León Galván, José Ignacio; Vázquez Pérez, Sergio; Portillo Guisado, Ramón Carlos; García Franquelo, Leopoldo; Domínguez, E.

    2010-01-01

    In this paper, a simple feed-forward modulation technique for single-phase two-cell multilevel cascaded converters is presented. All the possible switching states of the power converter are taken into account applying a two dimensional control region. The proposed technique uses the actual values of the DC-Link capacitor voltages to obtain output phase voltages and currents with low harmonic distortion with any dc voltage in the H-bridges of the cascaded converter. The possible switching sequ...

  19. IMPLEMENTATION OF A BPSK MODULATION BASED COGNITIVE RADIO SYSTEM USING THE ENERGY DETECTION TECHNIQUE

    Sid Ahmed Chouakri1

    2015-11-01

    Full Text Available We present in this work an energy detection algorithm, based on spectral power estimation, in the context of cognitive radio. The algorithm is based on the Neyman-Pearson test where the robustness of the appropriate spectral bands identification, is based, at one hand, on the ‘judicious’ choice of the probability of detection (PD and false alarm probability (PF. First, we accomplish a comparative study between two techniques for estimation of PSD (Power Spectral Density: the periodogram and Welch methods. Also, the interest is focused on the choice of the optimal duration of observation where we can state that this latter one should be inversely proportional to the level of the SNR of the transmitted signal to be sensed. The developed algorithm is applied in the context of cognitive radio. The algorithm aims to identify the free spectral bands representing, reserved for the primary user, of the signal carrying information, issued from an ASCII encoding alphanumeric message and utilizing the BPSK modulation, transmitted through an AWGN (Added White Gaussian Noise channel. The algorithm succeeds in identifying the free spectral bands even for low SNR levels (e.g. to -2 dB and allocate them to the informative signal representing the secondary user.

  20. Waveguide-type optical passive ring resonator gyro using frequency modulation spectroscopy technique

    Liang, Ning; Lijun, Guo; Mei, Kong; Tuoyuan, Chen

    2014-12-01

    This paper reports the experimental results of silica on a silicon ring resonator in a resonator micro optic gyroscope based on the frequency modulation spectroscopy technique by our research group. The ring resonator is composed of a 4 cm diameter silica waveguide. By testing at λ = 1550 nm, the FSR, FWHM and the depth of resonance are 3122 MHz, 103.07 MHz and 0.8 respectively. By using a polarization controller, the resonance curve under the TM mode can be inhibited. The depth of resonance increased from 0.8 to 0.8913, namely the finesse increase from 30.33 to 33.05. In the experiments, there is an acoustic-optical frequency shifter (AOFS) in each light loop. We lock the lasing frequency at the resonance frequency of the silica waveguide ring resonator for the counterclockwise lightwave; the frequency difference between the driving frequencies of the two AOFS is equivalent to the Sagnac frequency difference caused by gyro rotation. Thus, the gyro output is observed. The slope of the linear fit is about 0.330 mV/(°/s) based on the -900 to 900 kHz equivalent frequency and the gyro dynamic range is ±2.0 × 103 rad/s.

  1. Waveguide-type optical passive ring resonator gyro using frequency modulation spectroscopy technique

    This paper reports the experimental results of silica on a silicon ring resonator in a resonator micro optic gyroscope based on the frequency modulation spectroscopy technique by our research group. The ring resonator is composed of a 4 cm diameter silica waveguide. By testing at λ = 1550 nm, the FSR, FWHM and the depth of resonance are 3122 MHz, 103.07 MHz and 0.8 respectively. By using a polarization controller, the resonance curve under the TM mode can be inhibited. The depth of resonance increased from 0.8 to 0.8913, namely the finesse increase from 30.33 to 33.05. In the experiments, there is an acoustic-optical frequency shifter (AOFS) in each light loop. We lock the lasing frequency at the resonance frequency of the silica waveguide ring resonator for the counterclockwise lightwave; the frequency difference between the driving frequencies of the two AOFS is equivalent to the Sagnac frequency difference caused by gyro rotation. Thus, the gyro output is observed. The slope of the linear fit is about 0.330 mV/(°/s) based on the −900 to 900 kHz equivalent frequency and the gyro dynamic range is ±2.0 × 103 rad/s. (semiconductor devices)

  2. Joint Adaptive Modulation Coding and Cooperative ARQ over Relay Channels-Applications to Land Mobile Satellite Communications

    Mardani, Morteza; Lahouti, Farshad; Eliasi, Behrouz

    2008-01-01

    In a cooperative relay network, a relay node (R) facilitates data transmission to the destination node (D), when the latter is unable to decode the source node (S) data correctly. This paper considers such a system model and presents a cross-layer approach to jointly design adaptive modulation and coding (AMC) at the physical layer and cooperative truncated automatic repeat request (ARQ) protocol at the data link layer. We first derive a closed form expression for the spectral efficiency of the joint cooperative ARQ-AMC scheme. Aiming at maximizing this performance measure, we then optimize two AMC schemes for S-D and R-D links, which directly satisfy a prescribed packet loss rate constraint. As an interesting application, we also consider the problem of joint link adaptation and blockage mitigation in land mobile satellite communications (LMSC). We also present a new relay-assisted transmission protocol for LMSC, which delivers the source data to the destination via the relaying link, when the S-D channel is...

  3. Integer-linear-programing optimization in scalable video multicast with adaptive modulation and coding in wireless networks.

    Lee, Dongyul; Lee, Chaewoo

    2014-01-01

    The advancement in wideband wireless network supports real time services such as IPTV and live video streaming. However, because of the sharing nature of the wireless medium, efficient resource allocation has been studied to achieve a high level of acceptability and proliferation of wireless multimedia. Scalable video coding (SVC) with adaptive modulation and coding (AMC) provides an excellent solution for wireless video streaming. By assigning different modulation and coding schemes (MCSs) to video layers, SVC can provide good video quality to users in good channel conditions and also basic video quality to users in bad channel conditions. For optimal resource allocation, a key issue in applying SVC in the wireless multicast service is how to assign MCSs and the time resources to each SVC layer in the heterogeneous channel condition. We formulate this problem with integer linear programming (ILP) and provide numerical results to show the performance under 802.16 m environment. The result shows that our methodology enhances the overall system throughput compared to an existing algorithm. PMID:25276862

  4. A Novel Technique of Measuring SOA Differential Carrier Lifetime and a -Factor Using SOA Optical Modulation Response

    Ki-Hyuk; Lee; Woo-Young; Choi

    2003-01-01

    We demonstrate a new technique of measuring differential carrier lifetime and linewidth enhancement factor in a semiconductor optical amplifier. In our method, the optical responses and fiber transfer functions of a self-gain modulated SOA are measured and, from these, values of carrier lifetimes and linewidth enhancement factors are determined for various SOA input optical powers.

  5. Background Noise Reduction in Wind Tunnels using Adaptive Noise Cancellation and Cepstral Echo Removal Techniques for Microphone Array Applications

    Spalt, Taylor B

    2010-01-01

    Two experiments were conducted to investigate Adaptive Noise Cancelling and Cepstrum echo removal post-processing techniques on acoustic data from a linear microphone array in an anechoic chamber. A point source speaker driven with white noise was used as the primary signal. The first experiment included a background speaker to provide interference noise at three different Signal-to-Noise Ratios to simulate noise propagating down a wind tunnel circuit. The second experiment contained only the...

  6. Simulation of energy saving potential of a centralized HVAC system in an academic building using adaptive cooling technique

    Highlights: • We have simulated and validated the cooling loads of a multi-zone academic building, in a tropical region. • We have analyzed the effect of occupancy patterns on the cooling loads. • Adaptive cooling technique has been utilized to minimize the energy usage of HVAC system. • The results are promising and show a reduction of energy saving in the range of 20–30%. - Abstract: Application of adaptive comfort temperature as room temperature set points potentially reduce energy usage of the HVAC system during a cooling and heating period. The savings are mainly due to higher indoor temperature set point during hot period and lower indoor temperature set point during cold period than the recommended value. Numerous works have been carried out to show how much energy can be saved during cooling and heating period by applying adaptive comfort temperature. The previous work, however, focused on a continuous cooling load as found in many office and residential buildings. Therefore, this paper aims to simulate the energy saving potential for an academic glazed building in tropical Malaysian climate by developing adaptive cooling technique. A building simulation program (TRNSYS) was used to model the building and simulate the cooling load characteristic using current and proposed technique. Two experimental measurements were conducted and the results were used to validate the model. Finally, cooling load characteristic of the academic building using current and proposed technique were compared and the results showed that annual energy saving potential as much as 305,150 kW h can be achieved

  7. Radiation treatment for the right naris in a pediatric anesthesia patient using an adaptive oral airway technique

    Radiation therapy for pediatric patients often includes the use of intravenous anesthesia with supplemental oxygen delivered via the nasal cannula. Here, we describe the use of an adaptive anesthesia technique for electron irradiation of the right naris in a preschool-aged patient treated under anesthesia. The need for an intranasal bolus plug precluded the use of standard oxygen supplementation. This novel technique required the multidisciplinary expertise of anesthesiologists, radiation therapists, medical dosimetrists, medical physicists, and radiation oncologists to ensure a safe and reproducible treatment course

  8. Radiation treatment for the right naris in a pediatric anesthesia patient using an adaptive oral airway technique

    Sponseller, Patricia, E-mail: sponselp@uw.edu; Pelly, Nicole; Trister, Andrew; Ford, Eric; Ermoian, Ralph

    2015-10-01

    Radiation therapy for pediatric patients often includes the use of intravenous anesthesia with supplemental oxygen delivered via the nasal cannula. Here, we describe the use of an adaptive anesthesia technique for electron irradiation of the right naris in a preschool-aged patient treated under anesthesia. The need for an intranasal bolus plug precluded the use of standard oxygen supplementation. This novel technique required the multidisciplinary expertise of anesthesiologists, radiation therapists, medical dosimetrists, medical physicists, and radiation oncologists to ensure a safe and reproducible treatment course.

  9. A Rapid Model Adaptation Technique for Emotional Speech Recognition with Style Estimation Based on Multiple-Regression HMM

    Ijima, Yusuke; Nose, Takashi; Tachibana, Makoto; Kobayashi, Takao

    In this paper, we propose a rapid model adaptation technique for emotional speech recognition which enables us to extract paralinguistic information as well as linguistic information contained in speech signals. This technique is based on style estimation and style adaptation using a multiple-regression HMM (MRHMM). In the MRHMM, the mean parameters of the output probability density function are controlled by a low-dimensional parameter vector, called a style vector, which corresponds to a set of the explanatory variables of the multiple regression. The recognition process consists of two stages. In the first stage, the style vector that represents the emotional expression category and the intensity of its expressiveness for the input speech is estimated on a sentence-by-sentence basis. Next, the acoustic models are adapted using the estimated style vector, and then standard HMM-based speech recognition is performed in the second stage. We assess the performance of the proposed technique in the recognition of simulated emotional speech uttered by both professional narrators and non-professional speakers.

  10. Dosimetric Evaluation of Different Intensity-Modulated Radiotherapy Techniques for Breast Cancer After Conservative Surgery.

    Zhang, Fuli; Wang, Yadi; Xu, Weidong; Jiang, Huayong; Liu, Qingzhi; Gao, Junmao; Yao, Bo; Hou, Jun; He, Heliang

    2015-10-01

    Intensity-modulated radiotherapy (IMRT) potentially leads to a more favorite dose distribution compared to 3-dimensional or conventional tangential radiotherapy (RT) for breast cancer after conservative surgery or mastectomy. The aim of this study was to compare dosimetric parameters of the planning target volume (PTV) and organs at risk (OARs) among helical tomotherapy (HT), inverse-planned IMRT (IP-IMRT), and forward-planned field in field (FP-FIF) IMRT techniques after breast-conserving surgery. Computed tomography scans from 20 patients (12 left sided and 8 right sided) previously treated with T1N0 carcinoma were selected for this dosimetric planning study. We designed HT, IP-IMRT, and FP-FIF plans for each patient. Plans were compared according to dose-volume histogram analysis in terms of PTV homogeneity and conformity indices (HI and CI) as well as OARs dose and volume parameters. Both HI and CI of the PTV showed statistically significant difference among IP-IMRT, FP-FIF, and HT with those of HT were best (P IMRT showed smaller exposed volumes of ipsilateral lung, heart, contralateral lung, and breast, while HT indicated smaller exposed volumes of ipsilateral lung but larger exposed volumes of contralateral lung and breast as well as heart. In addition, HT demonstrated an increase in exposed volume of ipsilateral lung (except for fraction of lung volume receiving >30 Gy and 20 Gy), heart, contralateral lung, and breast compared with IP-IMRT. For breast cancer radiotherapy (RT) after conservative surgery, HT provides better dose homogeneity and conformity of PTV compared to IP-IMRT and FP-FIF techniques, especially for patients with supraclavicular lymph nodes involved. Meanwhile, HT decreases the OAR volumes receiving higher doses with an increase in the volumes receiving low doses, which is known to lead to an increased rate of radiation-induced secondary malignancies. Hence, composite factors including dosimetric advantage, clinical effect, and economic

  11. Periodic Noise Suppression from ECG Signal using Novel Adaptive Filtering Techniques

    Yogesh Sharma

    2012-03-01

    Full Text Available Electrocardiogram signal most commonly known recognized and used biomedical signal for medical examination of heart. The ECG signal is very sensitive in nature, and even if small noise mixed with original signal, the various characteristics of the signal changes, Data corrupted with noise must either filtered or discarded, filtering is important issue for design consideration of real time heart monitoring systems. Various filters used for removing the noise from ECG signals, most commonly used filters are Notch Filters, FIR filters, IIR filters, Wiener filter, Adaptive filters etc. Performance analysis shows that the best result is obtained by using Adaptive filter to remove various noises from ECG signal and get significant SNR andMSE results. In this paper a novel adaptive approach by using LMS algorithm and delay has shown whichcan be used for pre-processing of ECG signal and give appreciable result.

  12. Intensity-modulated radiation therapy and volumetric-modulated arc therapy for adult craniospinal irradiation—A comparison with traditional techniques

    Craniospinal irradiation (CSI) poses a challenging planning process because of the complex target volume. Traditional 3D conformal CSI does not spare any critical organs, resulting in toxicity in patients. Here the dosimetric advantages of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) are compared with classic conformal planning in adults for both cranial and spine fields to develop a clinically feasible technique that is both effective and efficient. Ten adult patients treated with CSI were retrospectively identified. For the cranial fields, 5-field IMRT and dual 356° VMAT arcs were compared with opposed lateral 3D conformal radiotherapy (3D-CRT) fields. For the spine fields, traditional posterior-anterior (PA) PA fields were compared with isocentric 5-field IMRT plans and single 200° VMAT arcs. Two adult patients have been treated using this IMRT technique to date and extensive quality assurance, especially for the junction regions, was performed. For the cranial fields, the IMRT technique had the highest planned target volume (PTV) maximum and was the least efficient, whereas the VMAT technique provided the greatest parotid sparing with better efficiency. 3D-CRT provided the most efficient delivery but with the highest parotid dose. For the spine fields, VMAT provided the best PTV coverage but had the highest mean dose to all organs at risk (OAR). 3D-CRT had the highest PTV and OAR maximum doses but was the most efficient. IMRT provides the greatest OAR sparing but the longest delivery time. For those patients with unresectable disease that can benefit from a higher, definitive dose, 3D-CRT–opposed laterals are the most clinically feasible technique for cranial fields and for spine fields. Although inefficient, the IMRT technique is the most clinically feasible because of the increased mean OAR dose with the VMAT technique. Quality assurance of the beams, especially the junction regions, is essential

  13. Intensity-modulated radiation therapy and volumetric-modulated arc therapy for adult craniospinal irradiation—A comparison with traditional techniques

    Studenski, Matthew T., E-mail: matthew.studenski@jeffersonhospital.org [Department of Radiation Oncology, Jefferson Medical College and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA (United States); Shen, Xinglei; Yu, Yan; Xiao, Ying; Shi, Wenyin [Department of Radiation Oncology, Jefferson Medical College and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA (United States); Biswas, Tithi [Department of Radiation Oncology, Brody School of Medicine, East Carolina University, Greenville, NC (United States); Werner-Wasik, Maria; Harrison, Amy S. [Department of Radiation Oncology, Jefferson Medical College and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA (United States)

    2013-04-01

    Craniospinal irradiation (CSI) poses a challenging planning process because of the complex target volume. Traditional 3D conformal CSI does not spare any critical organs, resulting in toxicity in patients. Here the dosimetric advantages of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) are compared with classic conformal planning in adults for both cranial and spine fields to develop a clinically feasible technique that is both effective and efficient. Ten adult patients treated with CSI were retrospectively identified. For the cranial fields, 5-field IMRT and dual 356° VMAT arcs were compared with opposed lateral 3D conformal radiotherapy (3D-CRT) fields. For the spine fields, traditional posterior-anterior (PA) PA fields were compared with isocentric 5-field IMRT plans and single 200° VMAT arcs. Two adult patients have been treated using this IMRT technique to date and extensive quality assurance, especially for the junction regions, was performed. For the cranial fields, the IMRT technique had the highest planned target volume (PTV) maximum and was the least efficient, whereas the VMAT technique provided the greatest parotid sparing with better efficiency. 3D-CRT provided the most efficient delivery but with the highest parotid dose. For the spine fields, VMAT provided the best PTV coverage but had the highest mean dose to all organs at risk (OAR). 3D-CRT had the highest PTV and OAR maximum doses but was the most efficient. IMRT provides the greatest OAR sparing but the longest delivery time. For those patients with unresectable disease that can benefit from a higher, definitive dose, 3D-CRT–opposed laterals are the most clinically feasible technique for cranial fields and for spine fields. Although inefficient, the IMRT technique is the most clinically feasible because of the increased mean OAR dose with the VMAT technique. Quality assurance of the beams, especially the junction regions, is essential.

  14. System and technique for retrieving depth information about a surface by projecting a composite image of modulated light patterns

    Hassebrook, Laurence G. (Inventor); Lau, Daniel L. (Inventor); Guan, Chun (Inventor)

    2010-01-01

    A technique, associated system and program code, for retrieving depth information about at least one surface of an object, such as an anatomical feature. Core features include: projecting a composite image comprising a plurality of modulated structured light patterns, at the anatomical feature; capturing an image reflected from the surface; and recovering pattern information from the reflected image, for each of the modulated structured light patterns. Pattern information is preferably recovered for each modulated structured light pattern used to create the composite, by performing a demodulation of the reflected image. Reconstruction of the surface can be accomplished by using depth information from the recovered patterns to produce a depth map/mapping thereof. Each signal waveform used for the modulation of a respective structured light pattern, is distinct from each of the other signal waveforms used for the modulation of other structured light patterns of a composite image; these signal waveforms may be selected from suitable types in any combination of distinct signal waveforms, provided the waveforms used are uncorrelated with respect to each other. The depth map/mapping to be utilized in a host of applications, for example: displaying a 3-D view of the object; virtual reality user-interaction interface with a computerized device; face--or other animal feature or inanimate object--recognition and comparison techniques for security or identification purposes; and 3-D video teleconferencing/telecollaboration.

  15. Adaptive resource allocation technique to stochastic multimodal projects : a distributed platform implementation in JAVA

    Tereso, Anabela Pereira; Mota, João; Lameiro, Rui

    2005-01-01

    This paper presents the implementation of the dynamic programming model (introduced in a previous paper) for the resolution of the adaptive resource allocation problem in stochastic multimodal project networks. A distributed platform using an Object Oriented language, Java, is used in order to take advantage of the available computational resources.

  16. En Français S'il Vous Plaît: Translation and Adaptation of the New England Collaborative Data Management Curriculum’s Introductory Module

    Natalie Clairoux

    2015-01-01

    The New England Collaborative Data Management Curriculum (NECDMC) is “an instructional tool for teaching data management best practices to undergraduates, graduate students, and researchers in the health sciences” (Lamar Soutter Library 2015a). This article reports on the French translation and adaptation of the first module of the NECDMC as part of the design of a short library instruction workshop.

  17. Adaptive antenna system for OFDMA WiMAX radio-over-fiber links using a directly modulated R-SOA and optical filtering

    Presi, Marco; Prince, Kamau; Chiuchiarelli, Andrea; Cerutti, Isabella; Constabile, Giampiero; Tafur Monroy, Idelfonso; Ciaramella, Ernesto

    We implement an adaptive beam steering system based on a directly-modulated unseeded reflective SOA. this system allows the distribution of 2.4 GHz 64-QAM OFDMA signals with 2048-subcarriers (72 Mb/s) satisfying the IEEE 802.16e specifications...

  18. Analysis and Minimization of Output Current Ripple for Discontinuous Pulse-Width Modulation Techniques in Three-Phase Inverters

    Gabriele Grandi

    2016-05-01

    Full Text Available This paper gives the complete analysis of the output current ripple in three-phase voltage source inverters considering the different discontinuous pulse-width modulation (DPWM strategies. In particular, peak-to-peak current ripple amplitude is analytically evaluated over the fundamental period and compared among the most used DPWMs, including positive and negative clamped (DPWM+ and DPWM−, and the four possible combinations between them, usually named as DPWM0, DPWM1, DPWM2, and DPWM3. The maximum and the average values of peak-to-peak current ripple are estimated, and a simple method to correlate the ripple envelope with the ripple rms is proposed and verified. Furthermore, all the results obtained by DPWMs are compared to the centered pulse-width modulation (CPWM, equivalent to the space vector modulation to identify the optimal pulse-width modulation (PWM strategy as a function of the modulation index, taking into account the different average switching frequency. In this way, the PWM technique providing for the minimum output current ripple is identified over the whole modulation range. The analytical developments and the main results are experimentally verified by current ripple measurements with a three-phase PWM inverter prototype supplying an induction motor load.

  19. Performance Analysis of the Different Null Steering Techniques in the Field of Adaptive Beamforming

    Fawad Zaman; Bilal Shoaib; Zafar Ullah Khan; Shahid Mehmood

    2013-01-01

    In this study, we compare the performance of three null steering techniques using uniform linear array. These techniques include Null Steering without using Phase Shifters, Null Steering by Decoupling the Real Weights and Null Steering by Decoupling the Complex Weights. The evaluation criteria of these techniques is based on the bases of different parameters i.e., null depth, main beam width, side lobe levels, number of steerable nulls, computational complexity and number of sensors used in t...

  20. Performance Analysis of the Different Null Steering Techniques in the Field of Adaptive Beamforming

    Fawad Zaman

    2013-04-01

    Full Text Available In this study, we compare the performance of three null steering techniques using uniform linear array. These techniques include Null Steering without using Phase Shifters, Null Steering by Decoupling the Real Weights and Null Steering by Decoupling the Complex Weights. The evaluation criteria of these techniques is based on the bases of different parameters i.e., null depth, main beam width, side lobe levels, number of steerable nulls, computational complexity and number of sensors used in the array. The validity and effectiveness of these techniques is reflected by the resultant radiation pattern of the array.

  1. Assessment of Multi-Joint Coordination and Adaptation in Standing Balance: A Novel Device and System Identification Technique.

    Engelhart, Denise; Schouten, Alfred C; Aarts, Ronald G K M; van der Kooij, Herman

    2015-11-01

    The ankles and hips play an important role in maintaining standing balance and the coordination between joints adapts with task and conditions, like the disturbance magnitude and type, and changes with age. Assessment of multi-joint coordination requires the application of multiple continuous and independent disturbances and closed loop system identification techniques (CLSIT). This paper presents a novel device, the double inverted pendulum perturbator (DIPP), which can apply disturbing forces at the hip level and between the shoulder blades. In addition to the disturbances, the device can provide force fields to study adaptation of multi-joint coordination. The performance of the DIPP and a novel CLSIT was assessed by identifying a system with known mechanical properties and model simulations. A double inverted pendulum was successfully identified, while force fields were able to keep the pendulum upright. The estimated dynamics were similar as the theoretical derived dynamics. The DIPP has a sufficient bandwidth of 7 Hz to identify multi-joint coordination dynamics. An experiment with human subjects where a stabilizing force field was rendered at the hip (1500 N/m), showed that subjects adapt by lowering their control actions around the ankles. The stiffness from upper and lower segment motion to ankle torque dropped with 30% and 48%, respectively. Our methods allow to study (pathological) changes in multi-joint coordination as well as adaptive capacity to maintain standing balance. PMID:25423654

  2. Adaptive cytoprotection through modulation of nitric oxide in ethanol-evoked gastritis

    Joshua Ka-Shun Ko; Chi-Hin Cho; Shiu-Kum Lam

    2004-01-01

    AIM: To assess the mechanisms of protective action by different mild irritants through maintenance of gastric mucosal integrity and modulation of mucosal nitric oxide (NO) in experimental gastritis rats.METHODS: Either 200 ml/L ethanol, 50 g/L NaCl or 0.3 mol/LHCl was pretreated to normal or 800 mL/L ethanol-induced acute gastritis Sprague-Dawley rats before a subsequent challenge with 500 mL/L ethanol. Both macroscopic lesion areas and histological damage scores were determined in the gastric mucosa of each group of animals. Besides,gastric mucosal activities of NO synthase isoforms and of superoxide dismutase, along with mucosal level of leukotriene (LT)C4 were measured.RESULTS: Macroscopic mucosal damages were protected by 200 mL/L ethanol and 50 g/L NaCl in gastritis rats.However, although 200 mL/L ethanol could protect the surface layers of mucosal cells in normal animals (protection attenuated by NG-nitro-L-arginine methyl ester), no cytoprotection against deeper histological damages was found in gastritis rats. Besides, inducible NO synthase activity was increased in the mucosa of gastritis animals and unaltered by mild irritants. Nevertheless, the elevation in mucosal LTC4 level following 500 mL/L ethanol administration and under gastritis condition was significantly reduced by pretreatment of all three mild irritants in both normal and gastritis animals.CONCLUSION: These findings suggest that the aggravated 500 mL/L ethanol-evoked mucosal damages under gastritis condition could be due to increased inducible NO and LTC4 production in the gastric mucosa. Only 200 mL/L ethanol is truly "cytoprotective" at the surface glandular level of nongastritis mucosa. Furthermore, the macroscopic protection of the three mild irritants involves reduction of LTC4 level in both normal and gastritis mucosa, implicating preservation of the vasculature.

  3. Wind effect on PV module temperature: Analysis of different techniques for an accurate estimation.

    Schwingshackl, Clemens; Petitta, Marcello; Ernst Wagner, Jochen; Belluardo, Giorgio; Moser, David; Castelli, Mariapina; Zebisch, Marc; Tetzlaff, Anke

    2013-04-01

    In this abstract a study on the influence of wind to model the PV module temperature is presented. This study is carried out in the framework of the PV-Alps INTERREG project in which the potential of different photovoltaic technologies is analysed for alpine regions. The PV module temperature depends on different parameters, such as ambient temperature, irradiance, wind speed and PV technology [1]. In most models, a very simple approach is used, where the PV module temperature is calculated from NOCT (nominal operating cell temperature), ambient temperature and irradiance alone [2]. In this study the influence of wind speed on the PV module temperature was investigated. First, different approaches suggested by various authors were tested [1], [2], [3], [4], [5]. For our analysis, temperature, irradiance and wind data from a PV test facility at the airport Bolzano (South Tyrol, Italy) from the EURAC Institute of Renewable Energies were used. The PV module temperature was calculated with different models and compared to the measured PV module temperature at the single panels. The best results were achieved with the approach suggested by Skoplaki et al. [1]. Preliminary results indicate that for all PV technologies which were tested (monocrystalline, amorphous, microcrystalline and polycrystalline silicon and cadmium telluride), modelled and measured PV module temperatures show a higher agreement (RMSE about 3-4 K) compared to standard approaches in which wind is not considered. For further investigation the in-situ measured wind velocities were replaced with wind data from numerical weather forecast models (ECMWF, reanalysis fields). Our results show that the PV module temperature calculated with wind data from ECMWF is still in very good agreement with the measured one (R² > 0.9 for all technologies). Compared to the previous analysis, we find comparable mean values and an increasing standard deviation. These results open a promising approach for PV module

  4. An Optimized Technique of Increasing the Performance of Network Adapter on EML Layer

    Prashanth L

    2012-08-01

    Full Text Available Simple Network Adapter initially which acts as an interface between the Transaction server and Network Elements communicates over the channel through tcppdu. Presently the disadvantage being involved in tcppdu is to maintain the channel contention, reservation of channel bandwidth. The disadvantage being involved is certain features, version of network elements communicates by receiving the xml over the socket. So, it’s not possible to change the entire framework, but by updating the framework an XML Over Socket(XOS formation should be supported. The XOS implementation is being performed using Java language through mainly in JVM. Such that by this deployment machines would become easier and form a good communication gap between them. This simple network adapter being developed should support operations of the North bounded server and gives an established authorized, secured, reliable portal. The interface being developed should provide a good performance in meeting the network demands and operated conversions of respective objects

  5. Adaptive and Predictive Control of Liquid-Liquid Extractors Using Neural-Based Instantaneous Linearization Technique

    Mjalli, F. S.

    2006-01-01

    Nonlinearity of the extraction process is addressed via the application of instantaneous linearization to control the extract and raffinate concentrations. Two feed-forward neural networks with delayed inputs and outputs were trained and validated to capture the dynamics of the extraction process. These nonlinear models were then adopted in an instantaneous linearization algorithm into two control algorithms. The self-tuning adaptive control strategy was compared to an approximate model predi...

  6. A Novel Approach of Harris Corner Detection of Noisy Images using Adaptive Wavelet Thresholding Technique

    Dey, Nilanjan; Nandi, Pradipti; Barman, Nilanjana

    2012-01-01

    In this paper we propose a method of corner detection for obtaining features which is required to track and recognize objects within a noisy image. Corner detection of noisy images is a challenging task in image processing. Natural images often get corrupted by noise during acquisition and transmission. Though Corner detection of these noisy images does not provide desired results, hence de-noising is required. Adaptive wavelet thresholding approach is applied for the same.

  7. Using adaptive techniques to validate and correct an audience driven design of web sites

    Casteleyn, Sven; Garrigós Fernández, Irene; De Troyer, Olga

    2004-01-01

    An audience driven philosophy for web site design takes the different target audiences as an explicit starting point, and organizes the basic navigation structure accordingly. However, for the designer it is not always easy, or sometimes even impossible, to assess the different requirements of the different target audiences correctly. In this paper, we show how to correct for such possible flaws using adaptive behavior. A mechanism for detecting both missing and superfluous information in a c...

  8. Fuzzy-Based Adaptive Hybrid Burst Assembly Technique for Optical Burst Switched Networks

    Abubakar Muhammad Umaru; Muhammad Shafie Abd Latiff; Yahaya Coulibaly

    2014-01-01

    The optical burst switching (OBS) paradigm is perceived as an intermediate switching technology for future all-optical networks. Burst assembly that is the first process in OBS is the focus of this paper. In this paper, an intelligent hybrid burst assembly algorithm that is based on fuzzy logic is proposed. The new algorithm is evaluated against the traditional hybrid burst assembly algorithm and the fuzzy adaptive threshold (FAT) burst assembly algorithm via simulation. Simulation results sh...

  9. Adaptive Finite Elements for Systems of PDEs: Software Concepts, Multi-level Techniques and Parallelization

    Vey, Simon

    2008-01-01

    In the recent past, the field of scientific computing has become of more and more importance for scientific as well as for industrial research, playing a comparable role as experiment and theory do. This success of computational methods in scientific and engineering research is next to the enormous improvement of computer hardware to a large extend due to contributions from applied mathematicians, who have developed algorithms which make real life applications feasible. Examples are adaptive ...

  10. An Example of a Hakomi Technique Adapted for Functional Analytic Psychotherapy

    Collis, Peter

    2012-01-01

    Functional Analytic Psychotherapy (FAP) is a model of therapy that lends itself to integration with other therapy models. This paper aims to provide an example to assist others in assimilating techniques from other forms of therapy into FAP. A technique from the Hakomi Method is outlined and modified for FAP. As, on the whole, psychotherapy…

  11. A technique for improved stability of adaptive feedforward controllers without detailed uncertainty measurements

    Model errors in adaptive controllers for the reduction of broadband noise and vibrations may lead to unstable systems or increased error signals. Previous research on active structures with small damping has shown that the addition of a low-authority controller which increases damping in the system may lead to improved performance of an adaptive, high-authority controller. Other researchers have suggested the use of frequency dependent regularization based on measured uncertainties. In this paper an alternative method is presented that avoids the disadvantages of these methods, namely the additional complex hardware and the need to obtain detailed information on the uncertainties. An analysis is made of an adaptive feedforward controller in which a difference exists between the secondary path and the model as used in the controller. The real parts of the eigenvalues that determine the stability of the system are expressed in terms of the amount of uncertainty and the singular values of the secondary path. Modifications of the feedforward control scheme are suggested that aim to improve performance without requiring detailed uncertainty measurements. (paper)

  12. Adaption of egg and larvae sampling techniques for lake sturgeon and broadcast spawning fishes in a deep river

    Roseman, Edward F.; Kennedy, Gregory W.; Craig, Jaquelyn; Boase, James; Soper, Karen

    2011-01-01

    In this report we describe how we adapted two techniques for sampling lake sturgeon (Acipenser fulvescens) and other fish early life history stages to meet our research needs in the Detroit River, a deep, flowing Great Lakes connecting channel. First, we developed a buoy-less method for sampling fish eggs and spawning activity using egg mats deployed on the river bottom. The buoy-less method allowed us to fish gear in areas frequented by boaters and recreational anglers, thus eliminating surface obstructions that interfered with recreational and boating activities. The buoy-less method also reduced gear loss due to drift when masses of floating aquatic vegetation would accumulate on buoys and lines, increasing the drag on the gear and pulling it downstream. Second, we adapted a D-frame drift net system formerly employed in shallow streams to assess larval lake sturgeon dispersal for use in the deeper (>8 m) Detroit River using an anchor and buoy system.

  13. Feature-Based Adaptive Tolerance Tree (FATT): An Efficient Indexing Technique for Content-Based Image Retrieval Using Wavelet Transform

    AnandhaKumar, Dr P

    2010-01-01

    This paper introduces a novel indexing and access method, called Feature- Based Adaptive Tolerance Tree (FATT), using wavelet transform is proposed to organize large image data sets efficiently and to support popular image access mechanisms like Content Based Image Retrieval (CBIR).Conventional database systems are designed for managing textual and numerical data and retrieving such data is often based on simple comparisons of text or numerical values. However, this method is no longer adequate for images, since the digital presentation of images does not convey the reality of images. Retrieval of images become difficult when the database is very large. This paper addresses such problems and presents a novel indexing technique, Feature Based Adaptive Tolerance Tree (FATT), which is designed to bring an effective solution especially for indexing large databases. The proposed indexing scheme is then used along with a query by image content, in order to achieve the ultimate goal from the user point of view that ...

  14. Breathing adapted radiotherapy: final clinic results of the program for the support to costly innovating techniques (Stic) of 2003

    The authors report the comparison, from a clinic point of view, between breathing adapted conformational radiotherapy (BART) and conventional conformational radiotherapy, in the case of lung and breast cancers. The assessment comprised a clinic examination, a thoracic radiography, breathing functional tests, a thoracic scanography at different moments (3, 6, 12, 18 and 24 months), and dosimetric criteria for tumour target volumes and the different thoracic organs at risk. Data have been collected among more than six hundred patients. Breathing adapted techniques allow acute and late toxicity to be reduced, notably for the lung, heart and oesophagus during a lung irradiation. They are less interesting for mammary irradiation, but could be important for a radiotherapy of the left breast. Short communication

  15. Modulation techniques for the cascaded H-bridge multi-level converter

    Vodden, John Alan

    2012-01-01

    This thesis investigates space-vector modulation and one-dimensional modulation applied to the cascaded H-bridge multi-level converter as a model for one port of the UNIFLEX-PM power converter system. The UNIFLEX-PM converter is a modular system including galvanic isolation at medium frequency intended to replace transformers in future distribution and transmission systems. Power converters in this application must produce good quality voltage waveforms with low power loss. In this work, ...

  16. A New Optimized Data Clustering Technique using Cellular Automata and Adaptive Central Force Optimization (ACFO

    G. Srinivasa Rao

    2015-06-01

    Full Text Available As clustering techniques are gaining more important today, we propose a new clustering technique by means of ACFO and cellular automata. The cellular automata uniquely characterizes the condition of a cell at a specific moment by employing the data like the conditions of a reference cell together with its adjoining cell, total number of cells, restraint, transition function and neighbourhood calculation. With an eye on explaining the condition of the cell, morphological functions are executed on the image. In accordance with the four stages of the morphological process, the rural and the urban areas are grouped separately. In order to steer clear of the stochastic turbulences, the threshold is optimized by means of the ACFO. The test outcomes obtained vouchsafe superb performance of the innovative technique. The accomplishment of the new-fangled technique is assessed by using additional number of images and is contrasted with the traditional methods like CFO (Central Force Optimization and PSO (Particle Swarm Optimization.

  17. Module Testing Techniques for Nuclear Safety Critical Software Using LDRA Testing Tool

    The safety critical software in the I and C systems of nuclear power plants requires high functional integrity and reliability. To achieve those requirement goals, the safety critical software should be verified and tested according to related codes and standards through verification and validation (V and V) activities. The safety critical software testing is performed at various stages during the development of the software, and is generally classified as three major activities: module testing, system integration testing, and system validation testing. Module testing involves the evaluation of module level functions of hardware and software. System integration testing investigates the characteristics of a collection of modules and aims at establishing their correct interactions. System validation testing demonstrates that the complete system satisfies its functional requirements. In order to generate reliable software and reduce high maintenance cost, it is important that software testing is carried out at module level. Module testing for the nuclear safety critical software has rarely been performed by formal and proven testing tools because of its various constraints. LDRA testing tool is a widely used and proven tool set that provides powerful source code testing and analysis facilities for the V and V of general purpose software and safety critical software. Use of the tool set is indispensable where software is required to be reliable and as error-free as possible, and its use brings in substantial time and cost savings, and efficiency

  18. Scrap Cans Assayed in 55-Gallon Drums by Adapted Q2 Technique

    Salaymeh, S.R.

    2001-07-24

    This report describes an alternate assay technique developed to perform batch nondestructive assay (NDA) of ten scrap cans at a time. This report also discusses and compares the results of the one batch of ten scrap cans by assaying them individually at the 324-M assay station with the alternate assay technique developed to perform batch NDA of ten scrap cans at a time using the Q2.

  19. SU-E-T-309: Tangential Modulated Arc Therapy: A Novel Technique for the Treatment of Superficial Disease

    Hadsell, M; Chin, E; Li, R; Xing, L; Bush, K [Stanford University Cancer Center, Stanford, CA (United States)

    2014-06-01

    Purpose: We propose a new type of treatment that employs a modulated and sliding tangential photon field to provide superior coverage of superficial targets when compared to other commonly employed methods while drastically reducing dose to the underlying sensitive structures often present in these cases. Methods: Modulated treatment plans were formulated for a set of three representative cases. The first was a revised treatment of a scalp sarcoma, while the second was a treatment of a right posterior chest wall sarcoma. For these cases, asymmetric jaw placement, angular limitations, and central isocenter placements were used to force the optimization algorithm into finding solutions with beamlines that were not perpendicular to the body surface. The final case targeted the chest wall of a breast cancer patient, in which standard treatments were compared to the use of modulated fields with multiple isocenters along the chest wall. Results: When compared with unrestricted modulated arcs, the tangential arc scalp treatment reduced the max and mean doses delivered to the brain by 33Gy (from 55 to 22Gy) and 6Gy (from 14Gy to 8Gy), respectively. In the right posterior chest wall case, the V10 in the ipsilateral lung was kept below 5% while retaining a Rx dose (45Gy) target coverage of over 97%. For the breast case, the modulated plan achieved reductions in high dose to the ipsilateral lung and heart by a factor of 2–3 when compared to classic laterally opposed tangents and reduced the V5 by 40% when compared to standard modulated arcs. Conclusion: Tangential modulated arc therapy has outperformed the conventional modalities of treatment for superficial lesions used in our clinic. We hope that with the advent of digitally controlled linear accelerators, we can uncover further benefits of this new technique and extend its applicability to a wider section of the patient population.

  20. An automatic CT-guided adaptive radiation therapy technique by online modification of multileaf collimator leaf positions for prostate cancer

    Purpose: To propose and evaluate online adaptive radiation therapy (ART) using in-room computed tomography (CT) imaging that detects changes in the target position and shape of the prostate and seminal vesicles (SVs) and then automatically modifies the multileaf collimator (MLC) leaf pairs in a slice-by-slice fashion. Methods and materials: For intensity-modulated radiation therapy (IMRT) using a coplanar beam arrangement, each MLC leaf pair projects onto a specific anatomic slice. The proposed strategy assumes that shape deformation is a function of only the superior-inferior (SI) position. That is, there is no shape change within a CT slice, but each slice can be displaced in the anteroposterior (AP) or right-left (RL) direction relative to adjacent slices. First, global shifts (in SI, AP, and RL directions) were calculated by three-dimensional (3D) registration of the bulk of the prostate in the treatment planning CT images with the daily CT images taken immediately before treatment. Local shifts in the AP direction were then found using slice-by-slice registration, in which the CT slices were individually registered. The translational shift within a slice could then be projected to a translational shift in the position of the corresponding MLC leaf pair for each treatment segment for each gantry angle. Global shifts in the SI direction were accounted for by moving the open portal superiorly or inferiorly by an integral number of leaf pairs. The proposed slice-by-slice registration technique was tested by using daily CT images from 46 CT image sets (23 each from 2 patients) taken before the standard delivery of IMRT for prostate cancer. A dosimetric evaluation was carried out by using an 8-field IMRT plan. Results: The shifts and shape change of the prostate and SVs could be separated into 3D global shifts in the RL, AP, and SI directions, plus local shifts in the AP direction, which were different for each CT slice. The MLC leaf positions were successfully

  1. Low Bit-Rate Image Compression using Adaptive Down-Sampling technique

    V.Swathi; Prof. K ASHOK BABU

    2011-01-01

    In this paper, we are going to use a practical approach of uniform down sampling in image space and yet making the sampling adaptive by spatially varying, directional low-pass pre-filtering. The resulting down-sampled pre-filtered image remains a conventional square sample grid, and, thus, it can be compressed and transmitted without any change to current image coding standards and systems. The decoder first decompresses the low-resolution image and then up-converts it to the original resolut...

  2. Adaptive Analog-to-Digital Conversion and pre-correlation Interference Mitigation Techniques in a GNSS receiver

    Lotz, Thorsten

    2008-01-01

    The objective of this diploma thesis was the development of pre-correlation interference mitigation techniques for a GNSS receiver. Since these developed algorithms shall be implemented in the real world DLR Galileo receiver, some pre-defined parameters were given that respects specifics of the hardware on which these algorithms shall work. So, a ideal 20 dB AGC and a ideal 14 bit ADC were available for the adaptive A/D-conversion, gain steering should be performed on the ADC o...

  3. 自适应传感器模块(ASIM)设计%Design of an adaptive sensor interface module

    吴亮; 侯立刚

    2015-01-01

    A design that transforms a variety of different types of sensors interfaces into a standardized USB port is pro⁃posed based on FPGA to achieve the fast reading and writing of the data collected though sensor interface by the host PC. The implementation method of USB controller based on hardware description language of Verilog is described. An adaptive system module is build by the application of QuartusⅡ and NiosⅡ software. The system is verified by the data transmission. The method of transforming UART port into USB port is simulated.%基于FPGA提出一种将各种不同类型的传感器接口(如UART接口)转化为统一规范的USB接口的设计方案,从而实现PC机对传感器接口采集的数据快速读写。简单介绍USB控制器的Verilog HDL实现方法,并应用Quartus Ⅱ和Nios Ⅱ软件搭建自适应传感器系统模块,通过数据传输对该系统进行验证,模拟了UART接口转换为USB接口的实现方法。

  4. Adaptive critic learning techniques for engine torque and air-fuel ratio control.

    Liu, Derong; Javaherian, Hossein; Kovalenko, Olesia; Huang, Ting

    2008-08-01

    A new approach for engine calibration and control is proposed. In this paper, we present our research results on the implementation of adaptive critic designs for self-learning control of automotive engines. A class of adaptive critic designs that can be classified as (model-free) action-dependent heuristic dynamic programming is used in this research project. The goals of the present learning control design for automotive engines include improved performance, reduced emissions, and maintained optimum performance under various operating conditions. Using the data from a test vehicle with a V8 engine, we developed a neural network model of the engine and neural network controllers based on the idea of approximate dynamic programming to achieve optimal control. We have developed and simulated self-learning neural network controllers for both engine torque (TRQ) and exhaust air-fuel ratio (AFR) control. The goal of TRQ control and AFR control is to track the commanded values. For both control problems, excellent neural network controller transient performance has been achieved. PMID:18632389

  5. Low Bit-Rate Image Compression using Adaptive Down-Sampling technique

    V.Swathi

    2011-09-01

    Full Text Available In this paper, we are going to use a practical approach of uniform down sampling in image space and yet making the sampling adaptive by spatially varying, directional low-pass pre-filtering. The resulting down-sampled pre-filtered image remains a conventional square sample grid, and, thus, it can be compressed and transmitted without any change to current image coding standards and systems. The decoder first decompresses the low-resolution image and then up-converts it to the original resolution in a constrained least squares restoration process, using a 2-D piecewise autoregressive model and the knowledge of directional low-pass pre-filtering. The proposed compression approach of collaborative adaptive down-sampling and up-conversion (CADU outperforms JPEG 2000 in PSNR measure at low to medium bit rates and achieves superior visual quality, as well. The superior low bit-rate performance of the CADU approach seems to suggest that over-sampling not only wastes hardware resources and energy, and it could be counterproductive to image quality given a tight bit budget.

  6. The adaptation of GDL motion recognition system to sport and rehabilitation techniques analysis.

    Hachaj, Tomasz; Ogiela, Marek R

    2016-06-01

    The main novelty of this paper is presenting the adaptation of Gesture Description Language (GDL) methodology to sport and rehabilitation data analysis and classification. In this paper we showed that Lua language can be successfully used for adaptation of the GDL classifier to those tasks. The newly applied scripting language allows easily extension and integration of classifier with other software technologies and applications. The obtained execution speed allows using the methodology in the real-time motion capture data processing where capturing frequency differs from 100 Hz to even 500 Hz depending on number of features or classes to be calculated and recognized. Due to this fact the proposed methodology can be used to the high-end motion capture system. We anticipate that using novel, efficient and effective method will highly help both sport trainers and physiotherapist in they practice. The proposed approach can be directly applied to motion capture data kinematics analysis (evaluation of motion without regard to the forces that cause that motion). The ability to apply pattern recognition methods for GDL description can be utilized in virtual reality environment and used for sport training or rehabilitation treatment. PMID:27106581

  7. Accurate Adaptive Level Set Method and Sharpening Technique for Three Dimensional Deforming Interfaces

    Kim, Hyoungin; Liou, Meng-Sing

    2011-01-01

    In this paper, we demonstrate improved accuracy of the level set method for resolving deforming interfaces by proposing two key elements: (1) accurate level set solutions on adapted Cartesian grids by judiciously choosing interpolation polynomials in regions of different grid levels and (2) enhanced reinitialization by an interface sharpening procedure. The level set equation is solved using a fifth order WENO scheme or a second order central differencing scheme depending on availability of uniform stencils at each grid point. Grid adaptation criteria are determined so that the Hamiltonian functions at nodes adjacent to interfaces are always calculated by the fifth order WENO scheme. This selective usage between the fifth order WENO and second order central differencing schemes is confirmed to give more accurate results compared to those in literature for standard test problems. In order to further improve accuracy especially near thin filaments, we suggest an artificial sharpening method, which is in a similar form with the conventional re-initialization method but utilizes sign of curvature instead of sign of the level set function. Consequently, volume loss due to numerical dissipation on thin filaments is remarkably reduced for the test problems

  8. Base isolation technique for tokamak type fusion reactor using adaptive control

    In this paper relating to the isolation device of heavy structure such as nuclear fusion reactor, a control rule for reducing the response acceleration and relative displacement simultaneously was formulated, and the aseismic performance was improved by employing the adaptive control method of changing the damping factors of the system adaptively every moment. The control rule was studied by computer simulation, and the aseismic effect was evaluated in an experiment employing a scale model. As a results, the following conclusions were obtained. (1) By employing the control rule presented in this paper, both absolute acceleration and relative displacement can be reduced simultaneously without making the system unstable. (2) By introducing this control rule in a scale model assuming the Tokamak type fusion reactor, the response acceleration can be suppressed down to 78 % and also the relative displacement to 79 % as compared with the conventional aseismic method. (3) The sensitivities of absolute acceleration and relative displacement with respect to the control gain are not equal. However, by employing the relative weighting factor between the absolute acceleration and relative displacement, it is possible to increase the control capability for any kind of objective structures and appliances. (author)

  9. An adaptive threshold based image processing technique for improved glaucoma detection and classification.

    Issac, Ashish; Partha Sarathi, M; Dutta, Malay Kishore

    2015-11-01

    Glaucoma is an optic neuropathy which is one of the main causes of permanent blindness worldwide. This paper presents an automatic image processing based method for detection of glaucoma from the digital fundus images. In this proposed work, the discriminatory parameters of glaucoma infection, such as cup to disc ratio (CDR), neuro retinal rim (NRR) area and blood vessels in different regions of the optic disc has been used as features and fed as inputs to learning algorithms for glaucoma diagnosis. These features which have discriminatory changes with the occurrence of glaucoma are strategically used for training the classifiers to improve the accuracy of identification. The segmentation of optic disc and cup based on adaptive threshold of the pixel intensities lying in the optic nerve head region. Unlike existing methods the proposed algorithm is based on an adaptive threshold that uses local features from the fundus image for segmentation of optic cup and optic disc making it invariant to the quality of the image and noise content which may find wider acceptability. The experimental results indicate that such features are more significant in comparison to the statistical or textural features as considered in existing works. The proposed work achieves an accuracy of 94.11% with a sensitivity of 100%. A comparison of the proposed work with the existing methods indicates that the proposed approach has improved accuracy of classification glaucoma from a digital fundus which may be considered clinically significant. PMID:26321351

  10. Design of mm-RoF System Based on OFM Technique with Optimized OFDM Modulation

    林如俭,; 陈翔,; 张林,; 叶家骏,; 宋英雄,; 李迎春

    2012-01-01

    We present the design of a novel bi-directional millimeter-wave radio-over-fiber (mm-RoF) system based on the millimeter-wave generation by optical frequency multiplication (OFM).A dual-drive Mach-Zehnder modulator is used to generate high-order optical side-modes which beat in the photo-detector,producing a 40-GHz carrier.Over 100-Mb/s orthogonal frequency division multiplexing (OFDM) modulation scheme is employed.The emphasis is on developing a mathematical model for optimizing optical modulation index to the Mach-Zehnder intensity modulator (IM) for OFDM signal with high peak-to-average power ratio which imposes a limitation on the system bit error rate (BER) performance due to the non-linearity of IM.The theoretical analysis on conposite carrier to composite triple beat ratio is performed based on which extension to the system BER formula for quadrature phase shift keying/ multiple quadrature amplitude modulation (QPSK/MQAM) format is presented.The experimental proof is given in a 40-GHz RoF system at a bit rate of up to 280 Mb/s in 100-MHz bandwidth.

  11. Occlusion Culling Algorithm Using Prefetching and Adaptive Level of Detail Technique

    ZHENG Fu-ren; ZHAN Shou-yi; Yang Bing

    2006-01-01

    A novel approach that integrates occlusion culling within the view-dependent rendering framework is proposed. The algorithm uses the prioritized-layered projection(PLP) algorithm to occlude those obscured objects, and uses an approximate visibility technique to accurately and efficiently determine which objects will be visible in the coming future and prefetch those objects from disk before they are rendered. View-dependent rendering technique provides the ability to change level of detail over the surface seamlessly and smoothly in real-time according to cell solidity value.

  12. Path Integral Molecular Dynamics within the Grand Canonical-like Adaptive Resolution Technique: Quantum-Classical Simulation of Liquid Water

    Agarwal, Animesh

    2015-01-01

    Quantum effects due to the spatial delocalization of light atoms are treated in molecular simulation via the path integral technique. Among several methods, Path Integral (PI) Molecular Dynamics (MD) is nowadays a powerful tool to investigate properties induced by spatial delocalization of atoms; however computationally this technique is very demanding. The abovementioned limitation implies the restriction of PIMD applications to relatively small systems and short time scales. One possible solution to overcome size and time limitation is to introduce PIMD algorithms into the Adaptive Resolution Simulation Scheme (AdResS). AdResS requires a relatively small region treated at path integral level and embeds it into a large molecular reservoir consisting of generic spherical coarse grained molecules. It was previously shown that the realization of the idea above, at a simple level, produced reasonable results for toy systems or simple/test systems like liquid parahydrogen. Encouraged by previous results, in this ...

  13. Design of a Stability Augmentation System for an Unmanned Helicopter Based on Adaptive Control Techniques

    Shouzhao Sheng

    2015-09-01

    Full Text Available The task of control of unmanned helicopters is rather complicated in the presence of parametric uncertainties and measurement noises. This paper presents an adaptive model feedback control algorithm for an unmanned helicopter stability augmentation system. The proposed algorithm can achieve a guaranteed model reference tracking performance and speed up the convergence rates of adjustable parameters, even when the plant parameters vary rapidly. Moreover, the model feedback strategy in the algorithm further contributes to the improvement in the control quality of the stability augmentation system in the case of low signal to noise ratios, mainly because the model feedback path is noise free. The effectiveness and superiority of the proposed algorithm are demonstrated through a series of tests.

  14. The application and evaluation of adaptive hypermedia techniques in Web-based medical education

    Muan Hong Ng

    2002-12-01

    Full Text Available This article discusses the design issues involved in delivering Web-based learning materials. An existing application in the medical domain - JointZone - is used to illustrate how personalization and an interactive environment can be incorporated into Web-based learning. This work applies the combination of an adaptive hypermedia, situated-learning approach and hypermedia linking concepts to facilitate online learning. A usability study was carried out on the work described and an evaluation was undertaken to measure the effect of personalization on various learning factors. The evaluation outcome was analysed subjectively and objectively. The results proved to be contradictory but, nevertheless, the work gives new insights into the use of technology to support learning

  15. CLUSTERING BASED ADAPTIVE IMAGE COMPRESSION SCHEME USING PARTICLE SWARM OPTIMIZATION TECHNIQUE

    M.Mohamed Ismail,

    2010-10-01

    Full Text Available This paper presents an image compression scheme with particle swarm optimization technique for clustering. The PSO technique is a powerful general purpose optimization technique that uses the concept of fitness.It provides a mechanism such that individuals in the swarm communicate and exchange information which is similar to the social behaviour of insects & human beings. Because of the mimicking the social sharing of information ,PSO directs particle to search the solution more efficiently.PSO is like a GA in that the population isinitialized with random potential solutions.The adjustment towards the best individual experience (PBEST and the best social experience (GBEST.Is conceptually similar to the cross over operaton of the GA.However it is unlike a GA in that each potential solution , called a particle is flying through the solution space with a velocity.Moreover the particles and the swarm have memory,which does not exist in the populatiom of GA.This optimization technique is used in Image compression and better results have obtained in terms of PSNR, CR and the visual quality of the image when compared to other existing methods.

  16. Problems on holographic imaging technique and adapt lasers for bubble chambers

    Different types of holographic recording technique for bubble chambers are presented and compared. The influence of turbulence on resolution is discussed as well as the demand on laser equipment. Experiments on a test model of HOLEBC using a pulsed ruby laser are also presented. (orig.)

  17. Problems on holographic imaging technique and adapt lasers for bubble chambers

    Bjelkhagen, H I

    1982-01-01

    Different types of holographic recording technique for bubble chambers are presented and compared. The influence of turbulence on resolution is discussed as well as the demand on laser equipment. Experiments on a test model of HOLEBC using a pulsed ruby laser are also presented.

  18. A Novel Pulse-Based Modulation Technique for Wideband Low Power Communication with Neuroprosthetic Devices

    Inanlou, Farzad; Kiani, Mehdi; Ghovanloo, Maysam

    2010-01-01

    Pulse Harmonic Modulation (PHM) is a novel pulse-based (carrierless) modulation method for wideband, low power data transmission across inductive telemetry links that operate in the near-field domain. PHM utilizes two or more unidentical pulses during each bit period to minimize intersymbol interference (ISI). In this paper, we describe the PHM concept and demonstrate its operation with a proof-of-concept prototype, which achieves a data rate of 5.2 Mbps at 1 cm coil separation with a bit err...

  19. A region growing technique adapted to precise micro calcification characterization in mammography

    To-day, mammography is the only breast screening technique capable of detecting breast cancer at a very early stage. The presence of a breast tumor is indicated by some features on the mammogram. One sign of malignancy is the presence of clusters of fine, granular micro-calcifications. We present here a new three-step method for detecting and characterizing these micro-calcifications. We design with the detection of potential candidates ('seeds'). The aim of this first step is to detect all the pixels be a micro-calcification. Then we focus on our specific region growing technique which provides an accurate extraction of the shape of the region corresponding to each detected seed. This second step is essential because micro-calcifications shape is a very important feature for the diagnosis. It is then possible to determine precise parameters to characterize these micro-calcifications. (authors)

  20. A phase-locked laser system based on modulation technique for atom interferometry

    Li, Wei; Song, Ningfang; Xu, Xiaobin; Lu, Xiangxiang

    2016-01-01

    We demonstrate a Raman laser system based on phase modulation technology and phase feedback control. The two laser beams with frequency difference of 6.835 GHz are modulated using electro-optic and acousto-optic modulators, respectively. Parasitic frequency components produced by the electro-optic modulator are filtered using a Fabry-Perot Etalon. A straightforward phase feedback system restrains the phase noise induced by environmental perturbations. The phase noise of the laser system stays below -125 rad2/Hz at frequency offset higher than 500 kHz. Overall phase noise of the laser system is evaluated by calculating the contribution of the phase noise to the sensitivity limit of a gravimeter. The results reveal that the sensitivity limited by the phase noise of our laser system is lower than that of a state-of-art optical phase-lock loop scheme when a gravimeter operates at short pulse duration, which makes the laser system a promising option for our future application of atom interferometer.

  1. The technique of high power laser beam combination using liquid crystal spatial light modulator

    Duan, Ying-ying; Wang, Xiang-ru; Huang, Zi-qiang

    2013-09-01

    Based on the phase modulation characteristics of optically addressed liquid crystal spatial light modulator (OA-LC-SLM) which is realized by controlling the power of addressing light, a physical model of coherent beam combination fiber laser using a bunch of fibers and a device of OA-LC-SLM is established on the theory of diffraction optics and liquid crystal birefringence effect. On the basis of this model, the properties of given scheme of coherent beam combination fiber laser are investigated including main lobe distribution and ability of phase modulation. Meanwhile, the plot functions of phase modulation versus the optical power of addressing light are obtained on different given driving voltage conditions and fiber alignment parameters such as core diameter and filling factor. After the numerical simulation, it shows that, this coherent beam combination fiber laser using OA-LC-SLM demonstrates an ability of coherent beam combination on the far field. With the increase of core diameter, the combination efficiency is improved better, and the divergence angle decreases narrower.

  2. Adaptive Techniques for Minimizing Middleware Memory Footprint for Distributed, Real-Time, Embedded Systems

    Panahi, Mark; Harmon, Trevor; Klefstad, Raymond

    2003-01-01

    In order for middleware to be widely useful for distributed, real-time, and embedded systems, it should provide a full set of services and be easily customizable to meet the memory footprint limitations of embedded systems. In this paper, we examine a variety of techniques used to reduce memory footprint in middleware. We found that combining aspect-oriented programming with code shrinkers and obfuscators reduces the memory footprint of CORBA middleware to

  3. Adaptive proactive reconfiguration: a technique for process variability and aging aware SRAM cache design

    Pouyan, Peyman; Amat Bertran, Esteve; Rubio Sola, Jose Antonio

    2014-01-01

    Nanoscale circuits are subject to a wide range of new limiting phenomena making essential to investigate new design strategies at the circuit and architecture level to improve its performance and reliability. Proactive reconfiguration is an emerging technique oriented to extend the system lifetime of memories affected by aging. In this brief, we present a new approach for static random access memory (SRAM) design that extends the cache lifetime when considering process variation and aging in ...

  4. TH-C-12A-04: Dosimetric Evaluation of a Modulated Arc Technique for Total Body Irradiation

    Tsiamas, P; Czerminska, M; Makrigiorgos, G; Karen, M; Zygmanski, P [Brigham and Women' s Hospital/ Dana-Farber Institute/ Harvard Medical School, Boston, MA (United States)

    2014-06-15

    Purpose: A simplified Total Body Irradiation (TBI) was developed to work with minimal requirements in a compact linac room without custom motorized TBI couch. Results were compared to our existing fixed-gantry double 4 MV linac TBI system with prone patient and simultaneous AP/PA irradiation. Methods: Modulated arc irradiates patient positioned in prone/supine positions along the craniocaudal axis. A simplified inverse planning method developed to optimize dose rate as a function of gantry angle for various patient sizes without the need of graphical 3D treatment planning system. This method can be easily adapted and used with minimal resources. Fixed maximum field size (40×40 cm2) is used to decrease radiation delivery time. Dose rate as a function of gantry angle is optimized to result in uniform dose inside rectangular phantoms of various sizes and a custom VMAT DICOM plans were generated using a DICOM editor tool. Monte Carlo simulations, film and ionization chamber dosimetry for various setups were used to derive and test an extended SSD beam model based on PDD/OAR profiles for Varian 6EX/ TX. Measurements were obtained using solid water phantoms. Dose rate modulation function was determined for various size patients (100cm − 200cm). Depending on the size of the patient arc range varied from 100° to 120°. Results: A PDD/OAR based beam model for modulated arc TBI therapy was developed. Lateral dose profiles produced were similar to profiles of our existing TBI facility. Calculated delivery time and full arc depended on the size of the patient (∼8min/ 100° − 10min/ 120°, 100 cGy). Dose heterogeneity varied by about ±5% − ±10% depending on the patient size and distance to the surface (buildup region). Conclusion: TBI using simplified modulated arc along craniocaudal axis of different size patients positioned on the floor can be achieved without graphical / inverse 3D planning.

  5. Develop techniques for ion implantation of PLZT [lead-lanthanum-zirconate-titanate] for adaptive optics

    Research was conducted at Pacific Northwest Laboratory to develop high photosensitivity adaptive optical elements utilizing ion implanted lanthanum-doped lead-zirconate-titanate (PLZT). One centimeter square samples were prepared by implanting ferroelectric and anti-ferroelectric PLZT with a variety of species or combinations of species. These included Ne, O, Ni, Ne/Cr, Ne/Al, Ne/Ni, Ne/O, and Ni/O, at a variety of energies and fluences. An indium-tin oxide (ITO) electrode coating was designed to give a balance of high conductivity and optical transmission at near uv to near ir wavelengths. Samples were characterized for photosensitivity; implanted layer thickness, index of refraction, and density; electrode (ITO) conductivity; and in some cases, residual stress curvature. Thin film anti-ferroelectric PLZT was deposited in a preliminary experiment. The structure was amorphous with x-ray diffraction showing the beginnings of a structure at substrate temperatures of approximately 5500C. This report summarizes the research and provides a sampling of the data taken during the report period

  6. A framework for automated contour quality assurance in radiation therapy including adaptive techniques

    Contouring of targets and normal tissues is one of the largest sources of variability in radiation therapy treatment plans. Contours thus require a time intensive and error-prone quality assurance (QA) evaluation, limitations which also impair the facilitation of adaptive radiotherapy (ART). Here, an automated system for contour QA is developed using historical data (the ‘knowledge base’). A pilot study was performed with a knowledge base derived from 9 contours each from 29 head-and-neck treatment plans. Size, shape, relative position, and other clinically-relevant metrics and heuristically derived rules are determined. Metrics are extracted from input patient data and compared against rules determined from the knowledge base; a computer-learning component allows metrics to evolve with more input data, including patient specific data for ART. Nine additional plans containing 42 unique contouring errors were analyzed. 40/42 errors were detected as were 9 false positives. The results of this study imply knowledge-based contour QA could potentially enhance the safety and effectiveness of RT treatment plans as well as increase the efficiency of the treatment planning process, reducing labor and the cost of therapy for patients. (paper)

  7. A framework for automated contour quality assurance in radiation therapy including adaptive techniques

    Altman, M. B.; Kavanaugh, J. A.; Wooten, H. O.; Green, O. L.; DeWees, T. A.; Gay, H.; Thorstad, W. L.; Li, H.; Mutic, S.

    2015-07-01

    Contouring of targets and normal tissues is one of the largest sources of variability in radiation therapy treatment plans. Contours thus require a time intensive and error-prone quality assurance (QA) evaluation, limitations which also impair the facilitation of adaptive radiotherapy (ART). Here, an automated system for contour QA is developed using historical data (the ‘knowledge base’). A pilot study was performed with a knowledge base derived from 9 contours each from 29 head-and-neck treatment plans. Size, shape, relative position, and other clinically-relevant metrics and heuristically derived rules are determined. Metrics are extracted from input patient data and compared against rules determined from the knowledge base; a computer-learning component allows metrics to evolve with more input data, including patient specific data for ART. Nine additional plans containing 42 unique contouring errors were analyzed. 40/42 errors were detected as were 9 false positives. The results of this study imply knowledge-based contour QA could potentially enhance the safety and effectiveness of RT treatment plans as well as increase the efficiency of the treatment planning process, reducing labor and the cost of therapy for patients.

  8. An improved adaptive kriging-based importance technique for sampling multiple failure regions of low probability

    The estimation of system failure probabilities may be a difficult task when the values involved are very small, so that sampling-based Monte Carlo methods may become computationally impractical, especially if the computer codes used to model the system response require large computational efforts, both in terms of time and memory. This paper proposes a modification of an algorithm proposed in literature for the efficient estimation of small failure probabilities, which combines FORM to an adaptive kriging-based importance sampling strategy (AK-IS). The modification allows overcoming an important limitation of the original AK-IS in that it provides the algorithm with the flexibility to deal with multiple failure regions characterized by complex, non-linear limit states. The modified algorithm is shown to offer satisfactory results with reference to four case studies of literature, outperforming in general several other alternative methods of literature. - Highlights: • We tackle low failure probability estimation within reliability analysis context. • We improve a kriging-based importance sampling for estimating failure probabilities. • The new algorithm is capable of dealing with multiple-disconnected failure regions. • The performances are better than other methods of literature on 4 test case-studies

  9. Graphene Oxides Decorated with Carnosine as an Adjuvant To Modulate Innate Immune and Improve Adaptive Immunity in Vivo.

    Meng, Chunchun; Zhi, Xiao; Li, Chao; Li, Chuanfeng; Chen, Zongyan; Qiu, Xusheng; Ding, Chan; Ma, Lijun; Lu, Hongmin; Chen, Di; Liu, Guangqing; Cui, Daxiang

    2016-02-23

    Current studies have revealed the immune effects of graphene oxide (GO) and have utilized them as vaccine carriers and adjuvants. However, GO easily induces strong oxidative stress and inflammatory reaction at the site of injection. It is very necessary to develop an alternative adjuvant based on graphene oxide derivatives for improving immune responses and decreasing side effects. Carnosine (Car) is an outstanding and safe antioxidant. Herein, the feasibility and efficiency of ultrasmall graphene oxide decorated with carnosine as an alternative immune adjuvant were explored. OVA@GO-Car was prepared by simply mixing ovalbumin (OVA, a model antigen) with ultrasmall GO covalently modified with carnosine (GO-Car). We investigated the immunological properties of the GO-Car adjuvant in model mice. Results show that OVA@GO-Car can promote robust and durable OVA-specific antibody response, increase lymphocyte proliferation efficiency, and enhance CD4(+) T and CD8(+) T cell activation. The presence of Car in GO also probably contributes to enhancing the antigen-specific adaptive immune response through modulating the expression of some cytokines, including IL-6, CXCL1, CCL2, and CSF3. In addition, the safety of GO-Car as an adjuvant was evaluated comprehensively. No symptoms such as allergic response, inflammatory redness swelling, raised surface temperatures, physiological anomalies of blood, and remarkable weight changes were observed. Besides, after modification with carnosine, histological damages caused by GO-Car in lung, muscle, kidney, and spleen became weaken significantly. This study sufficiently suggest that GO-Car as a safe adjuvant can effectively enhance humoral and innate immune responses against antigens in vivo. PMID:26766427

  10. Adapting content-based image retrieval techniques for the semantic annotation of medical images.

    Kumar, Ashnil; Dyer, Shane; Kim, Jinman; Li, Changyang; Leong, Philip H W; Fulham, Michael; Feng, Dagan

    2016-04-01

    The automatic annotation of medical images is a prerequisite for building comprehensive semantic archives that can be used to enhance evidence-based diagnosis, physician education, and biomedical research. Annotation also has important applications in the automatic generation of structured radiology reports. Much of the prior research work has focused on annotating images with properties such as the modality of the image, or the biological system or body region being imaged. However, many challenges remain for the annotation of high-level semantic content in medical images (e.g., presence of calcification, vessel obstruction, etc.) due to the difficulty in discovering relationships and associations between low-level image features and high-level semantic concepts. This difficulty is further compounded by the lack of labelled training data. In this paper, we present a method for the automatic semantic annotation of medical images that leverages techniques from content-based image retrieval (CBIR). CBIR is a well-established image search technology that uses quantifiable low-level image features to represent the high-level semantic content depicted in those images. Our method extends CBIR techniques to identify or retrieve a collection of labelled images that have similar low-level features and then uses this collection to determine the best high-level semantic annotations. We demonstrate our annotation method using retrieval via weighted nearest-neighbour retrieval and multi-class classification to show that our approach is viable regardless of the underlying retrieval strategy. We experimentally compared our method with several well-established baseline techniques (classification and regression) and showed that our method achieved the highest accuracy in the annotation of liver computed tomography (CT) images. PMID:26890880

  11. Analysis of Adaptive Fuzzy Technique for Multiple Crack Diagnosis of Faulty Beam Using Vibration Signatures

    Amiya Kumar Dash

    2013-01-01

    Full Text Available This paper discusses the multicrack detection of structure using fuzzy Gaussian technique. The vibration parameters derived from the numerical methods of the cracked cantilever beam are used to set several fuzzy rules for designing the fuzzy controller used to predict the crack location and depth. Relative crack locations and relative crack depths are the output parameters from the fuzzy inference system. The method proposed in the current analysis is used to evaluate the dynamic response of cracked cantilever beam. The results of the proposed method are in good agreement with the results obtained from the developed experimental setup.

  12. Conception et adaptation de services techniques pour l'informatique ubiquitaire et nomade

    Lecomte, Sylvain

    2005-01-01

    Depuis la fin des années 1990, le développement des terminaux nomades et des réseaux sans fil s'est considérablement accéléré. Cela a provoqué l'apparition de nouvelles applications, très largement réparties, et offrant de nouveaux services, aussi bien aux usagers (applications de commerce électronique, télévision interactive, applications de proximité), qu'aux entreprises (développement du commerce B2B). Avec l'apparition de ces nouvelles applications, les services techniques, qui prennent e...

  13. Review of Adaptive Cell Selection Techniques in LTE-Advanced Heterogeneous Networks

    Gadam, M. A.; Ahmed, Maryam Abdulazeez; Ng, Chee Kyun; Nordin, Nor Kamariah; Sali, Aduwati; Hashim, Fazirulhisyam

    2016-01-01

    Poor cell selection is the main challenge in Picocell (PeNB) deployment in Long Term Evolution- (LTE-) Advanced heterogeneous networks (HetNets) because it results in load imbalance and intercell interference. A selection technique based on cell range extension (CRE) has been proposed for LTE-Advanced HetNets to extend the coverage of PeNBs for load balancing. However, poor CRE bias setting in cell selection inhibits the attainment of desired cell splitting gains. By contrast, a cell selectio...

  14. A general approach for temperature modulated thermogravimetry: Extension to non-periodical and event-controlled modulation

    Highlights: • The temperature modulated TGA technique is expanded to non-periodic modulation functions. • The use of a stochastic modulation function is tested. • The concept of the new technique, the event controlled temperature modulated TGA is introduced. • The event control adapted the intensity of the modulation function and the characteristic modulation time. The result is an optimized modulation. - Abstract: Sinusoidal temperature modulated thermogravimetric analysis (TMTGA) has been proposed to get kinetic data on reactions that were investigated by TGA 45 years ago by Flynn and later by Blaine and Hahn. Because of general uncertainties of this technique, we developed a generalized approach for TMTGA using any modulation function, i.e., periodic as well as non-periodic. As a consequence of an error discussion of a TMDSC experiment, we present a new concept of the event controlled modulation function

  15. Application of the modulated temperature differential scanning calorimetry technique for the determination of the specific heat of copper nanofluids

    The purpose of this work is to investigate the applicability of the modulated temperature differential scanning calorimetry technique to measure specific heat of copper nanofluids by using the ASTM E2719 standard procedure, which is generally applied to thermally stable solids and liquids. The one-step method of preparation of copper nanofluid samples is described. The synthesized nanoparticles were separated from the base fluid and examined by X-ray diffraction and transmission electron microscopy in order to evaluate their structure, morphology and chemical nature. The presence of copper nanoparticles in the base fluid alters the characteristics of crystallization and melting processes and reduces the specific heat values of nanofluids in the whole studied temperature range. - Highlights: ► Copper nanofluids prepared by one-step method. ► Methodology of synthesis improved nanofluid stability. ► Specific heat determinations using modulated temperature differential scanning calorimetry. ► Good agreement between theoretical and experimental values.

  16. APSLAP: an adaptive boosting technique for predicting subcellular localization of apoptosis protein.

    Saravanan, Vijayakumar; Lakshmi, P T V

    2013-12-01

    Apoptotic proteins play key roles in understanding the mechanism of programmed cell death. Knowledge about the subcellular localization of apoptotic protein is constructive in understanding the mechanism of programmed cell death, determining the functional characterization of the protein, screening candidates in drug design, and selecting protein for relevant studies. It is also proclaimed that the information required for determining the subcellular localization of protein resides in their corresponding amino acid sequence. In this work, a new biological feature, class pattern frequency of physiochemical descriptor, was effectively used in accordance with the amino acid composition, protein similarity measure, CTD (composition, translation, and distribution) of physiochemical descriptors, and sequence similarity to predict the subcellular localization of apoptosis protein. AdaBoost with the weak learner as Random-Forest was designed for the five modules and prediction is made based on the weighted voting system. Bench mark dataset of 317 apoptosis proteins were subjected to prediction by our system and the accuracy was found to be 100.0 and 92.4 %, and 90.1 % for self-consistency test, jack-knife test, and tenfold cross validation test respectively, which is 0.9 % higher than that of other existing methods. Beside this, the independent data (N151 and ZW98) set prediction resulted in the accuracy of 90.7 and 87.7 %, respectively. These results show that the protein feature represented by a combined feature vector along with AdaBoost algorithm holds well in effective prediction of subcellular localization of apoptosis proteins. The user friendly web interface "APSLAP" has been constructed, which is freely available at http://apslap.bicpu.edu.in and it is anticipated that this tool will play a significant role in determining the specific role of apoptosis proteins with reliability. PMID:23982307

  17. Vapor pressure data for fatty acids obtained using an adaptation of the DSC technique

    Highlights: ► Vapor pressure data of fatty acids were measured by Differential Scanning Calorimetry. ► The DSC technique is especially advantageous for expensive chemicals. ► High heating rate was used for measuring the vapor pressure data. ► Antoine constants were obtained for the selected fatty acids. - Abstract: The vapor pressure data for lauric (C12:0), myristic (C14:0), palmitic (C16:0), stearic (C18:0) and oleic (C18:1) acids were obtained using Differential Scanning Calorimetry (DSC). The adjustments made in the experimental procedure included the use of a small sphere (tungsten carbide) placed over the pinhole of the crucible (diameter of 0.8 mm), making it possible to use a faster heating rate than that of the standard method and reducing the experimental time. The measurements were made in the pressure range from 1333 to 9333 Pa, using small sample quantities of fatty acids (3–5 mg) at a heating rate of 25 K min−1. The results showed the effectiveness of the technique under study, as evidenced by the low temperature deviations in relation to the data reported in the literature. The Antoine constants were fitted to the experimental data whose values are shown in Table 5.

  18. Vapor pressure data for fatty acids obtained using an adaptation of the DSC technique

    Matricarde Falleiro, Rafael M. [LPT, Departamento de Processos Quimicos (DPQ), Faculdade de Engenharia Quimica, Universidade de Campinas (UNICAMP), 13083-852 Campinas - SP (Brazil); Akisawa Silva, Luciana Y. [Departamento de Ciencias Exatas e da Terra, Universidade Federal de Sao Paulo (UNIFESP), 09972-270 Diadema - SP (Brazil); Meirelles, Antonio J.A. [EXTRAE, Departamento de Engenharia de Alimentos (DEA), Faculdade de Engenharia de Alimentos, Universidade de Campinas (UNICAMP), 13083-862 Campinas - SP (Brazil); Kraehenbuehl, Maria A., E-mail: mak@feq.unicamp.br [LPT, Departamento de Processos Quimicos (DPQ), Faculdade de Engenharia Quimica, Universidade de Campinas (UNICAMP), 13083-852 Campinas - SP (Brazil)

    2012-11-10

    Highlights: Black-Right-Pointing-Pointer Vapor pressure data of fatty acids were measured by Differential Scanning Calorimetry. Black-Right-Pointing-Pointer The DSC technique is especially advantageous for expensive chemicals. Black-Right-Pointing-Pointer High heating rate was used for measuring the vapor pressure data. Black-Right-Pointing-Pointer Antoine constants were obtained for the selected fatty acids. - Abstract: The vapor pressure data for lauric (C{sub 12:0}), myristic (C{sub 14:0}), palmitic (C{sub 16:0}), stearic (C{sub 18:0}) and oleic (C{sub 18:1}) acids were obtained using Differential Scanning Calorimetry (DSC). The adjustments made in the experimental procedure included the use of a small sphere (tungsten carbide) placed over the pinhole of the crucible (diameter of 0.8 mm), making it possible to use a faster heating rate than that of the standard method and reducing the experimental time. The measurements were made in the pressure range from 1333 to 9333 Pa, using small sample quantities of fatty acids (3-5 mg) at a heating rate of 25 K min{sup -1}. The results showed the effectiveness of the technique under study, as evidenced by the low temperature deviations in relation to the data reported in the literature. The Antoine constants were fitted to the experimental data whose values are shown in Table 5.

  19. Roll and pitch set-up errors during volumetric modulated arc delivery. Can adapting gantry and collimator angles compensate

    Hoffmans-Holtzer, Nienke A.; Hoffmans, Daan; Dahele, Max; Slotman, Ben J.; Verbakel, Wilko F.A.R. [VU University Medical Center, Department of Radiation Oncology, Amsterdam (Netherlands)

    2014-11-28

    The purpose of this work was to investigate whether adapting gantry and collimator angles can compensate for roll and pitch setup errors during volumetric modulated arc therapy (VMAT) delivery. Previously delivered clinical plans for locally advanced head-and-neck (H and N) cancer (n = 5), localized prostate cancer (n = 2), and whole brain with simultaneous integrated boost to 5 metastases (WB + 5M, n = 1) were used for this study. Known rigid rotations were introduced in the planning CT scans. To compensate for these, in-house software was used to adapt gantry and collimator angles in the plan. Doses to planning target volumes (PTV) and critical organs at risk (OAR) were calculated with and without compensation and compared with the original clinical plan. Measurements in the sagittal plane in a polystyrene phantom using radiochromic film were compared by gamma (γ) evaluation for 2 H and N cancer patients. For H and N plans, the introduction of 2 -roll and 3 -pitch rotations reduced mean PTV coverage from 98.7 to 96.3 %. This improved to 98.1 % with gantry and collimator compensation. For prostate plans respective figures were 98.4, 97.5, and 98.4 %. For WB + 5M, compensation worked less well, especially for smaller volumes and volumes farther from the isocenter. Mean comparative γ evaluation (3 %, 1 mm) between original and pitched plans resulted in 86 % γ < 1. The corrected plan restored the mean comparison to 96 % γ < 1. Preliminary data suggest that adapting gantry and collimator angles is a promising way to correct roll and pitch set-up errors of < 3 during VMAT for H and N and prostate cancer. (orig.) [German] Das Ziel dieser Arbeit war es, zu untersuchen, ob Anpassungen von Gantry- und Kollimatorwinkeln Positionierungsfehler in VMAT-Bestrahlungsplaenen kompensieren koennen. Fuer diese Studie wurden zuvor angefertigte klinische Bestrahlungsplaene von lokal fortgeschrittenen Kopf-Hals-Tumoren (HNO, n = 5), Prostatatumoren (n = 2) und ganzen Schaedeln mit

  20. Percutaneous autonomic neural modulation: A novel technique to treat cardiac arrhythmia

    Ablation and anti-arrhythmic medications have shown promise but have been met with varying success and unwanted side effects such as myocardial injury, arrhythmias, and morbidity from invasive surgical intervention. The answer to improving efficacy of ablation may include modulation of the cardiac aspect of the autonomic nervous system. Our lab has developed a novel approach and device to navigate the oblique sinus and to use DC current and saline/alcohol irrigation to selectively stimulate and block the autonomic ganglia found on the epicardial side of the heart. This novel approach minimizes myocardial damage from thermal injury and provides a less invasive and targeted approach. For feasibility, proof-of-concept, and safety monitoring, we carried out canine studies to test this novel application. Our results suggest a safer and less invasive way of modulating arrhythmogenic substrate that may lead to improved treatment of AF in humans

  1. Percutaneous autonomic neural modulation: A novel technique to treat cardiac arrhythmia

    DeSimone, Christopher V.; Madhavan, Malini [Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN (United States); Venkatachalam, Kalpathi L. [Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Jacksonville, FL (United States); Knudson, Mark B. [Mayo Clinic, Rochester, MN (United States); EnteroMedics, EnteroMedics, St. Paul, MN (United States); Asirvatham, Samuel J., E-mail: asirvatham.samuel@mayo.edu [Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN (United States); Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN (United States)

    2013-05-15

    Ablation and anti-arrhythmic medications have shown promise but have been met with varying success and unwanted side effects such as myocardial injury, arrhythmias, and morbidity from invasive surgical intervention. The answer to improving efficacy of ablation may include modulation of the cardiac aspect of the autonomic nervous system. Our lab has developed a novel approach and device to navigate the oblique sinus and to use DC current and saline/alcohol irrigation to selectively stimulate and block the autonomic ganglia found on the epicardial side of the heart. This novel approach minimizes myocardial damage from thermal injury and provides a less invasive and targeted approach. For feasibility, proof-of-concept, and safety monitoring, we carried out canine studies to test this novel application. Our results suggest a safer and less invasive way of modulating arrhythmogenic substrate that may lead to improved treatment of AF in humans.

  2. Grayscale Image Transmission over Rayleigh Fading Channel in a MIMO System Using Different Digital Modulation Techniques with STBC

    Animish S. Andraskar

    2015-04-01

    Full Text Available The consistent demand for higher data rates and ability to send large volumes of data without compromising the quality of communication has led the development of a new generations of wireless systems. But range and data rate limitations are there in wireless devices. In an effort to overcome these limitations, Multi Input Multi Output (MIMO systems can be used which also increase diversity and improve the bit error rate (BER performance of wireless systems. They also increase the channel capacity, increase the transmitted data rate through spatial multiplexing, and/or reduce interference from other users. MIMO systems thus make a promising communication systems because of their high transmission rates without additional bandwidth or transmit power and robustness against multipath fading. This paper focuses on transmission of an image file using 2x2 MIMO system that achieves a full diversity gain using Alamouti’s Space Time Block Coding technique for 2 transmitting antennas and 2 receiving antennas. Different modulation techniques viz. BPSK, QPSK, 16-QAM and 64-QAM are used and performances has been evaluated in terms of BER vs. SNR to find out the best modulation technique in a given environment. Space-Time Codes have been used which in addition to the time and spectral domain, also exploit the spatial domain. Simple maximum likelihood decoding algorithm is used at the receiver side to decode the received encoded signal.

  3. Low-temperature ozone exposure technique to modulate the stoichiometry of WOx nanorods and optimize the electrochromic performance

    Lin, Feng; Li, Chi-Ping; Chen, Gang; Tenent, Robert C.; Wolden, Colin A.; Gillaspie, Dane T.; Dillon, Anne C.; Richards, Ryan M.; Engtrakul, Chaiwat

    2012-06-01

    A low-temperature ozone exposure technique was employed for the post-treatment of WOx nanorod thin films fabricated from hot-wire chemical vapor deposition (HWCVD) and ultrasonic spray deposition (USD) techniques. The resulting films were characterized with x-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, UV-vis-NIR spectroscopy and x-ray photoelectron spectroscopy (XPS). The stoichiometry and surface crystallinity of the WOx thin films were subsequently modulated upon ozone exposure and thermal annealing without particle growth. The electrochromic performance was studied in a LiClO4-propylene carbonate electrolyte, and the results suggest that the low-temperature ozone exposure technique is superior to the traditional high-temperature thermal annealing (employed to more fully oxidize the WOx). The optical modulation at 670 nm was improved from 35% for the as-deposited film to 57% for the film after ozone exposure at 150 °C. The coloration efficiency was improved and the switching speed to the darkened state was significantly accelerated from 18.0 s for the as-deposited film to 11.8 s for the film after the ozone exposure. The process opens an avenue for low-temperature and cost-effective manufacturing of electrochromic films, especially on flexible polymer substrates.

  4. Low-temperature ozone exposure technique to modulate the stoichiometry of WOx nanorods and optimize the electrochromic performance

    A low-temperature ozone exposure technique was employed for the post-treatment of WOx nanorod thin films fabricated from hot-wire chemical vapor deposition (HWCVD) and ultrasonic spray deposition (USD) techniques. The resulting films were characterized with x-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, UV–vis–NIR spectroscopy and x-ray photoelectron spectroscopy (XPS). The stoichiometry and surface crystallinity of the WOx thin films were subsequently modulated upon ozone exposure and thermal annealing without particle growth. The electrochromic performance was studied in a LiClO4–propylene carbonate electrolyte, and the results suggest that the low-temperature ozone exposure technique is superior to the traditional high-temperature thermal annealing (employed to more fully oxidize the WOx). The optical modulation at 670 nm was improved from 35% for the as-deposited film to 57% for the film after ozone exposure at 150 °C. The coloration efficiency was improved and the switching speed to the darkened state was significantly accelerated from 18.0 s for the as-deposited film to 11.8 s for the film after the ozone exposure. The process opens an avenue for low-temperature and cost-effective manufacturing of electrochromic films, especially on flexible polymer substrates. (paper)

  5. Equalization Technique for Balancing the Modulation Ratio Characteristics of the Single-Phase-to-Three-Phase Matrix Converter

    Vengadeshwaran Velu

    2016-01-01

    Full Text Available Three-phase system has numerous advantages over the single-phase system in terms of instantaneous power, stability, and cost. Three-phase systems are not available in every location particularly in remote rural areas, hill stations, low voltage distribution homes, and so forth. Having a system that is capable of converting directly the readily available single-phase system to three phases will have greater usability in various applications. The routine techniques adopted in the direct ac-ac single-phase-to-three-phase converters do not yield the best desired outputs because of their complexity in the segregation process and bidirectional nature of the input signal. Other initiatives use ac-dc-ac converters which are huge and costly due to dc link energy storage devices. Further, none of these systems provide a convincing result in producing the standard three-phase output voltages that are 120° away from each other. This paper proposes an effective direct ac-ac single-phase-to-three-phase conversion technique based on space vector pulse width modulation based matrix converter system that produces a convincing three-phase output signals from a single-phase source with balanced modulation index characteristics. The details of the scientific programming adopted on the proposed technique were presented.

  6. Resolution enhancement for ultrasonic echographic technique in non destructive testing with an adaptive deconvolution method

    The ultrasonic echographic technique has specific advantages which makes it essential in a lot of Non Destructive Testing (NDT) investigations. However, the high acoustic power necessary to propagate through highly attenuating media can only be transmitted by resonant transducers, which induces severe limitations of the resolution on the received echograms. This resolution may be improved with deconvolution methods. But one-dimensional deconvolution methods come up against problems in non destructive testing when the investigated medium is highly anisotropic and inhomogeneous (i.e. austenitic steel). Numerous deconvolution techniques are well documented in the NDT literature. But they often come from other application fields (biomedical engineering, geophysics) and we show they do not apply well to specific NDT problems: frequency-dependent attenuation and non-minimum phase of the emitted wavelet. We therefore introduce a new time-domain approach which takes into account the wavelet features. Our method solves the deconvolution problem as an estimation one and is performed in two steps: (i) A phase correction step which takes into account the phase of the wavelet and estimates a phase-corrected echogram. The phase of the wavelet is only due to the transducer and is assumed time-invariant during the propagation. (ii) A band equalization step which restores the spectral content of the ideal reflectivity. The two steps of the method are performed using fast Kalman filters which allow a significant reduction of the computational effort. Synthetic and actual results are given to prove that this is a good approach for resolution improvement in attenuating media

  7. Path integral molecular dynamics within the grand canonical-like adaptive resolution technique: Simulation of liquid water

    Agarwal, Animesh, E-mail: animesh@zedat.fu-berlin.de; Delle Site, Luigi, E-mail: dellesite@fu-berlin.de [Institute for Mathematics, Freie Universität Berlin, Berlin (Germany)

    2015-09-07

    Quantum effects due to the spatial delocalization of light atoms are treated in molecular simulation via the path integral technique. Among several methods, Path Integral (PI) Molecular Dynamics (MD) is nowadays a powerful tool to investigate properties induced by spatial delocalization of atoms; however, computationally this technique is very demanding. The above mentioned limitation implies the restriction of PIMD applications to relatively small systems and short time scales. One of the possible solutions to overcome size and time limitation is to introduce PIMD algorithms into the Adaptive Resolution Simulation Scheme (AdResS). AdResS requires a relatively small region treated at path integral level and embeds it into a large molecular reservoir consisting of generic spherical coarse grained molecules. It was previously shown that the realization of the idea above, at a simple level, produced reasonable results for toy systems or simple/test systems like liquid parahydrogen. Encouraged by previous results, in this paper, we show the simulation of liquid water at room conditions where AdResS, in its latest and more accurate Grand-Canonical-like version (GC-AdResS), is merged with two of the most relevant PIMD techniques available in the literature. The comparison of our results with those reported in the literature and/or with those obtained from full PIMD simulations shows a highly satisfactory agreement.

  8. Adapting of the Background-Oriented Schlieren (BOS) Technique in the Characterization of the Flow Regimes in Thermal Spraying Processes

    Tillmann, W.; Abdulgader, M.; Rademacher, H. G.; Anjami, N.; Hagen, L.

    2014-01-01

    In thermal spraying technique, the changes in the in-flight particle velocities are considered to be only a function of the drag forces caused by the dominating flow regimes in the spray jet. Therefore, the correct understanding of the aerodynamic phenomena occurred at nozzle out let and at the substrate interface is an important task in the targeted improvement in the nozzle and air-cap design as well as in the spraying process in total. The presented work deals with the adapting of an innovative technique for the flow characterization called background-oriented Schlieren. The flow regimes in twin wire arc spraying (TWAS) and high velocity oxygen fuel (HVOF) were analyzed with this technique. The interfering of the atomization gas flow with the intersected wires causes in case of TWAS process a deformation of the jet shape. It leads also to areas with different aero dynamic forces. The configurations of the outlet air-caps in TWAS effect predominantly the outlet flow characteristics. The ratio between fuel and oxygen determine the dominating flow regimes in the HVOF spraying jet. Enhanced understanding of the aerodynamics at outlet and at the substrate interface could lead to a targeted improvement in thermal spraying processes.

  9. Real time algorithm invariant to natural lighting with LBP techniques through an adaptive thresholding implemented in GPU processors

    Orjuela-Vargas, S. A.; Triana-Martinez, J.; Yañez, J. P.; Philips, W.

    2014-03-01

    Video analysis in real time requires fast and efficient algorithms to extract relevant information from a considerable number, commonly 25, of frames per second. Furthermore, robust algorithms for outdoor visual scenes may retrieve correspondent features along the day where a challenge is to deal with lighting changes. Currently, Local Binary Pattern (LBP) techniques are widely used for extracting features due to their robustness to illumination changes and the low requirements for implementation. We propose to compute an automatic threshold based on the distribution of the intensity residuals resulting from the pairwise comparisons when using LBP techniques. The intensity residuals distribution can be modelled by a Generalized Gaussian Distribution (GGD). In this paper we compute the adaptive threshold using the parameters of the GGD. We present a CUDA implementation of our proposed algorithm. We use the LBPSYM technique. Our approach is tested on videos of four different urban scenes with mobilities captured during day and night. The extracted features can be used in a further step to determine patterns, identify objects or detect background. However, further research must be conducted for blurring correction since the scenes at night are commonly blurred due to artificial lighting.

  10. Path integral molecular dynamics within the grand canonical-like adaptive resolution technique: Simulation of liquid water

    Agarwal, Animesh; Delle Site, Luigi

    2015-09-01

    Quantum effects due to the spatial delocalization of light atoms are treated in molecular simulation via the path integral technique. Among several methods, Path Integral (PI) Molecular Dynamics (MD) is nowadays a powerful tool to investigate properties induced by spatial delocalization of atoms; however, computationally this technique is very demanding. The above mentioned limitation implies the restriction of PIMD applications to relatively small systems and short time scales. One of the possible solutions to overcome size and time limitation is to introduce PIMD algorithms into the Adaptive Resolution Simulation Scheme (AdResS). AdResS requires a relatively small region treated at path integral level and embeds it into a large molecular reservoir consisting of generic spherical coarse grained molecules. It was previously shown that the realization of the idea above, at a simple level, produced reasonable results for toy systems or simple/test systems like liquid parahydrogen. Encouraged by previous results, in this paper, we show the simulation of liquid water at room conditions where AdResS, in its latest and more accurate Grand-Canonical-like version (GC-AdResS), is merged with two of the most relevant PIMD techniques available in the literature. The comparison of our results with those reported in the literature and/or with those obtained from full PIMD simulations shows a highly satisfactory agreement.

  11. Path integral molecular dynamics within the grand canonical-like adaptive resolution technique: Simulation of liquid water

    Quantum effects due to the spatial delocalization of light atoms are treated in molecular simulation via the path integral technique. Among several methods, Path Integral (PI) Molecular Dynamics (MD) is nowadays a powerful tool to investigate properties induced by spatial delocalization of atoms; however, computationally this technique is very demanding. The above mentioned limitation implies the restriction of PIMD applications to relatively small systems and short time scales. One of the possible solutions to overcome size and time limitation is to introduce PIMD algorithms into the Adaptive Resolution Simulation Scheme (AdResS). AdResS requires a relatively small region treated at path integral level and embeds it into a large molecular reservoir consisting of generic spherical coarse grained molecules. It was previously shown that the realization of the idea above, at a simple level, produced reasonable results for toy systems or simple/test systems like liquid parahydrogen. Encouraged by previous results, in this paper, we show the simulation of liquid water at room conditions where AdResS, in its latest and more accurate Grand-Canonical-like version (GC-AdResS), is merged with two of the most relevant PIMD techniques available in the literature. The comparison of our results with those reported in the literature and/or with those obtained from full PIMD simulations shows a highly satisfactory agreement

  12. Path integral molecular dynamics within the grand canonical-like adaptive resolution technique: Simulation of liquid water.

    Agarwal, Animesh; Delle Site, Luigi

    2015-09-01

    Quantum effects due to the spatial delocalization of light atoms are treated in molecular simulation via the path integral technique. Among several methods, Path Integral (PI) Molecular Dynamics (MD) is nowadays a powerful tool to investigate properties induced by spatial delocalization of atoms; however, computationally this technique is very demanding. The above mentioned limitation implies the restriction of PIMD applications to relatively small systems and short time scales. One of the possible solutions to overcome size and time limitation is to introduce PIMD algorithms into the Adaptive Resolution Simulation Scheme (AdResS). AdResS requires a relatively small region treated at path integral level and embeds it into a large molecular reservoir consisting of generic spherical coarse grained molecules. It was previously shown that the realization of the idea above, at a simple level, produced reasonable results for toy systems or simple/test systems like liquid parahydrogen. Encouraged by previous results, in this paper, we show the simulation of liquid water at room conditions where AdResS, in its latest and more accurate Grand-Canonical-like version (GC-AdResS), is merged with two of the most relevant PIMD techniques available in the literature. The comparison of our results with those reported in the literature and/or with those obtained from full PIMD simulations shows a highly satisfactory agreement. PMID:26342354

  13. The effect of head orientation on subarachnoid cerebrospinal fluid distribution and its implications for neurophysiological modulation and recording techniques

    Gravitational forces may lead to local changes in subarachnoid cerebrospinal fluid (CSF) layer thickness, which has important implications for neurophysiological modulation and recording techniques. This study examines the effect of gravitational pull associated with different head positions on the distribution of subarachnoid CSF using structural magnetic resonance imaging. Images of seven subjects in three different positions (supine, left lateral and prone) were statistically compared. Results suggest that subarachnoid CSF volume decreases on the side of the head closest to the ground, due to downward brain movement with gravity. These findings warrant future research into currently unexplored gravitation-induced changes in regional subarachnoid CSF thickness. (note)

  14. A novel technique for post-mastectomy breast irradiation utilising non-coplanar intensity-modulated radiation therapy

    Koshy, M; Zhang, B; S Naqvi; B. Liu; Mohiuddin, M M

    2010-01-01

    The aim of this study was to investigate if non-coplanar intensity-modulated radiation therapy (IMRT) in the post-mastectomy setting can reduce the dose to normal structures and improve target coverage. We compared this IMRT technique with a standard partial wide tangential (PWT) plan and a five-field (5F) photon-electron plan. 10 patients who underwent left-sided mastectomy were planned to 50.4 Gy using either (1) PWT to cover the internal mammary (IM) nodes and supraclavicular fields, (2) 5...

  15. An Adaptive Watermarking Technique for the copyright of digital images and Digital Image Protection

    Yusuf Perwej

    2012-04-01

    Full Text Available The Internet as a whole does not use secure links, thus information in transit may be vulnerable to interruption as well. The important of reducing a chance of the information being detected during the transmission is being an issue in the real world now days. The Digital watermarking method provides for the quick and inexpensive distribution of digital information over the Internet. This method provides new ways of ensuring the sufficient protection of copyright holders in the intellectual property dispersion process. The property of digital watermarking images allows insertion of additional data in the image without altering the value of the image. This message is hidden in unused visual space in the image and stays below the human visible threshold for the image. Both seek to embed information inside a cover message with little or no degradation of the cover-object. In this paper investigate the following relevant concepts and terminology, history of watermarks and the properties of a watermarking system as well as a type of watermarking and applications. We are proposing edge detection using Gabor Filters. In this paper we are proposed least significant bit (LSB substitution method to encrypt the message in the watermark image file. The benefits of the LSB are its simplicity to embed the bits of the message directly into the LSB plane of cover-image and many techniques using these methods. The LSB does not result in a human perceptible difference because the amplitude of the change is little therefore the human eye the resulting stego image will look identical to the cover image and this allows high perceptual transparency of the LSB. The spatial domain technique LSB substitution it would be able to use a pseudo-random number generator to determine the pixels to be used for embedding based on a given key. We are using DCT transform watermark algorithms based on robustness. The watermarking robustness have been calculated by the Peak Signal

  16. An Adaptive Watermarking Technique for the copyright of digital images and Digital Image Protection

    Yusuf Perwej

    2012-05-01

    Full Text Available The Internet as a whole does not use secure links, thus information in transit may be vulnerable to interruption as well. The important of reducing a chance of the information being detected during the transmission is being an issue in the real world now days. The Digital watermarking method provides for the quick and inexpensive distribution of digital information over the Internet. This method provides new ways of ensuring the sufficient protection of copyright holders in the intellectual property dispersion process. The property of digital watermarking images allows insertion of additional data in the image without altering the value of the image. This message is hidden in unused visual space in the image and stays below the human visible threshold for the image. Both seek to embed information inside a cover message with little or no degradation of the cover-object. In this paper investigate the following relevant concepts and terminology, history of watermarks and the properties of a watermarking system as well as a type of watermarking and applications. We are proposing edge detection using Gabor Filters. In this paper we are proposed least significant bit (LSB substitution method to encrypt the message in the watermark image file. The benefits of the LSB are its simplicity to embed the bits of the message directly into the LSB plane of cover-image and many techniques using these methods. The LSB does not result in a human perceptible difference because the amplitude of the change is little therefore the human eye the resulting stego image will look identical to the cover image and this allows high perceptual transparency of the LSB. The spatial domain technique LSB substitution it would be able to use a pseudo-random number generatorto determine the pixels to be used for embedding based on a given key. We are using DCT transform watermark algorithms based on robustness. The watermarking robustness have been calculated by the Peak Signal to

  17. An Improved Character Segmentation Algorithm Based on Local Adaptive Thresholding Technique for Chinese NvShu Documents

    Yangguang Sun

    2014-06-01

    Full Text Available For the structural characteristics of Chinese NvShu character, by combining the basic idea in LLT local threshold algorithm and introducing the maximal between-class variance algorithm into local windows, an improved character segmentation algorithm based on local adaptive thresholding technique for Chinese NvShu documents was presented in this paper. Because of designing the corresponding correction parameters for the threshold and using secondary search mechanism, our proposed method could not only automatically obtain local threshold, but also avoid the loss of the character image information and improve the accuracy of the character image segmentation. Experimental results demonstrated its capability to reduce the effect of background noise, especially for Chinese NvShu character images with uneven illumination and low contrast

  18. Breathing adapted radiotherapy for breast cancer: comparison of free breathing gating with the breath-hold technique

    Korreman, Stine Sofia; Pedersen, Anders N; Nøttrup, Trine Jakobi;

    2005-01-01

    BACKGROUND AND PURPOSE: Adjuvant radiotherapy after breast-conserving surgery for breast cancer implies a risk of late cardiac and pulmonary toxicity. This is the first study to evaluate cardiopulmonary dose sparing of breathing adapted radiotherapy (BART) using free breathing gating, and to...... compare this respiratory technique with voluntary breath-hold. PATIENTS AND METHODS: 17 patients were CT-scanned during non-coached breathing manoeuvre including free breathing (FB), end-inspiration gating (IG), end-expiration gating (EG), deep inspiration breath-hold (DIBH) and end-expiration breath......-hold (EBH). The Varian Real-time Position Management system (RPM) was used to monitor respiratory movement and to gate the scanner. For each breathing phase, a population based internal margin (IM) was estimated based on average chest wall excursion, and incorporated into an individually optimised three...

  19. Sorting of pistachio nuts using image processing techniques and an adaptive neural-fuzzy inference system

    A. R Abdollahnejad Barough

    2016-04-01

    . Finally, a total amount of the second moment (m2 and matrix vectors of image were selected as features. Features and rules produced from decision tree fed into an Adaptable Neuro-fuzzy Inference System (ANFIS. ANFIS provides a neural network based on Fuzzy Inference System (FIS can produce appropriate output corresponding input patterns. Results and Discussion: The proposed model was trained and tested inside ANFIS Editor of the MATLAB software. 300 images, including closed shell, pithy and empty pistachio were selected for training and testing. This network uses 200 data related to these two features and were trained over 200 courses, the accuracy of the result was 95.8%. 100 image have been used to test network over 40 courses with accuracy 97%. The time for the training and testing steps are 0.73 and 0.31 seconds, respectively, and the time to choose the features and rules was 2.1 seconds. Conclusions: In this study, a model was introduced to sort non- split nuts, blank nuts and filled nuts pistachios. Evaluation of training and testing, shows that the model has the ability to classify different types of nuts with high precision. In the previously proposed methods, merely non-split and split pistachio nuts were sorted and being filled or blank nuts is unrecognizable. Nevertheless, accuracy of the mentioned method is 95.56 percent. As well as, other method sorted non-split and split pistachio nuts with an accuracy of 98% and 85% respectively for training and testing steps. The model proposed in this study is better than the other methods and it is encouraging for the improvement and development of the model.

  20. Adapting desorption mass spectrometry and pattern recognition techniques to petroleum fluid correlation studies

    Hickey, J.C.; Durfee, S.L.

    1987-05-01

    Petroleum explorationists are often faced with determining the relationship between the products of wells completed in lithologies that may have some spatial or communicative relationship. Conventional methods of sampling and analysis are often time consuming and expensive. A new method for the sampling, analysis, and computerized data interpretation of the C2-C16 fraction of crude oil and natural gas is reported here. Controlled temperature headspace sampling of crude oils and direct pressure equilibrated natural gas exposure of carbon adsorption wires has been successfully applied to the sampling of the volatile fractions of petroleum fluids. Thermal vacuum desorption followed by mass spectrometric analysis of these volatile organic compounds is a rapid and sensitive method for obtaining detailed information of the distribution (fingerprint) of the components in a given sample; however, the resulting information is too complex for direct human interpretation. Techniques of computerized chemical pattern recognition such as principal components analysis (PCA) with graphical rotation, discriminant analysis, and similarity analysis (SIMCA) have proven useful in establishing the relationships between potentially correlated samples via the fingerprints of their volatile fractions. Studies have been conducted on multiple samples from numerous continental basins. The results of several of these studies will be presented to demonstrate the applicability of this new, rapid, cost-efficient approach to correlation studies.

  1. Performance Analysis of Convolution Coded WLAN Physical Layer under Different Modulation Techniques

    sanjeev kumar; Ginni Sharma; Parveen Kumar

    2010-01-01

    WLAN plays an important role as a complement to the existing or planned cellular networks which can offer high speed voice, video and data service up to the customer end. The aim of this paper is to analysis the performance of coded WLAN system for different digital modulation schemes (BPSK, 16-PSK, QPSK, 4-QAM and 16-QAM) under AWGN channel. The performance of convolution encoder WLAN system is in terms of graph between BER and SNR. We also verify the system performance with different code r...

  2. System design of programmable 4f phase modulation techniques for rapid intensity shaping: a conceptual comparison

    Roth, Matthias; Heber, Jörg; Janschek, Klaus

    2016-03-01

    The present study analyses three beam shaping approaches with respect to a light-efficient generation of i) patterns and ii) multiple spots by means of a generic optical 4f-setup. 4f approaches share the property that due to the one-to-one relationship between output intensity and input phase, the need for time-consuming, iterative calculation can be avoided. The resulting low computational complexity offers a particular advantage compared to the widely used holographic principles and makes them potential candidates for real-time applications. The increasing availability of high-speed phase modulators, e.g. on the basis of MEMS, calls for an evaluation of the performances of these concepts. Our second interest is the applicability of 4f methods to high-power applications. We discuss the variants of 4f intensity shaping by phase modulation from a system-level point of view which requires the consideration of application relevant boundary conditions. The discussion includes i) the micro mirror based phase manipulation combined with amplitude masking in the Fourier plane, ii) the Generalized Phase Contrast, and iii) matched phase-only correlation filtering combined with GPC. The conceptual comparison relies on comparative figures of merit for energy efficiency, pattern homogeneity, pattern image quality, maximum output intensity and flexibility with respect to the displayable pattern. Numerical simulations illustrate our findings.

  3. Electrostatic performance improvement of dual material cylindrical gate MOSFET using work-function modulation technique

    Jena, Biswajit; Dash, Sidhartha; Mishra, Guru Prasad

    2016-09-01

    In a continuous effort to increase the DC and RF figure-of-merits (FOMs), multigate MOSFETs have evolved from classical planar device into a gate all around structure. The unique design with accuracy in device performance has made it a cutting edge device to overcome the scaling and performance barrier of the present VLSI technology. The fabrication process of a surface channel device with proper threshold voltage (Vth) directly depends upon the work-function of the gate electrode. By keeping it in mind, a metal gate with linearly modulated work-function (5-4.2 ev) along the z-axis in a cylindrical surrounding gate MOSFET is introduced. This work demonstrates the potential benefits of work-function modulation based dual material cylindrical gate MOSFET (WMDMCG) in terms of DC performance characteristics. The present model provides improved DC performance as compared to conventional dual material cylindrical surrounding gate MOSFET (DMCG) and the results obtained are validated with TCAD device simulator from Synopsys.

  4. Measurement of LHCD edge power deposition through modulation techniques on Alcator C-Mod

    Faust, I. C.; Brunner, D.; LaBombard, B.; Parker, R. R.; Baek, S. G.; Chilenksi, M. A.; Hubbard, A.; Hughes, J. W.; Terry, J. L.; Shiraiwa, S.; Walk, J. R.; Wallace, G. M.; Whyte, D. G. [MIT Plasma Science and Fusion Center, Cambridge, MA USA (United States); Edlund, E. [Princeton Plasma Physics Laboratory, Princeton, NJ USA (United States)

    2015-12-10

    The efficiency of LHCD on Alcator C-Mod drops exponentially with line average density. At reactor relevant densities (> 1 · 1020 [m{sup −3}]) no measurable current is driven. While a number of causes have been suggested, no specific mechanism has been shown to be responsible for the loss of current drive at high density. Fast modulation of the LH power was used to isolate and quantify the LHCD deposition within the plasma. Measurements from these plasmas provide unique evidence for determining a root cause. Modulation of LH power in steady plasmas exhibited no correlated change in the core temperature. A correlated, prompt response in the edge suggests that the loss in efficiency is related to a edge absorption mechanism. This follows previous results which found the generation of n{sub ||}-independent SOL currents. Multiple Langmuir probe array measurements of the conducted heat conclude that the lost power is deposited near the last closed flux surface. The heat flux induced by LH waves onto the outer divertor is calculated. Changes in the neutral pressure, ionization and hard X-ray emission at high density highlight the importance of the active divertor in the loss of efficiency. Results of this study implicate a mechanism which may occur over multiple passes, leading to power absorption near the LCFS.

  5. Comparative Analysis of Different Digital Modulation Techniques on the Basis of Their Bit Error Rate in VHDL

    Rashmi Mongre

    2014-09-01

    Full Text Available In digital communication system design, the main objective is to receive data as similar as the data sent from the transmitter. It is important to analyze the system in term of probability of error to view the system's performance. Each modulation technique has different performance while dealing with signals, which normally are affected with noise. General explanation for BER is explained and simulated in this paper. It focuses on comparative performance analysis of BPSK, QPSK, 8PSK and 16PSK i.e. Mary PSK system where the value of M=2, 4, 8 and 16. VHSIC Hardware Description Language (HDL was used for committal to writing of the design. The Xilinx ISE 8.1i tool was used for synthesis of this project. ModelSim PE Student Edition 10.3c is used for functional simulation and logic verification of analog waveforms. The BER curves for different digital modulation techniques which are obtained after simulation are compared with theoretical curves. All the BER calculations are done assuming the channel as AWGN channel

  6. Comparison of conformal and intensity-modulated techniques for simultaneous integrated boost radiotherapy of upper esophageal carcinoma

    Wei-Hua Fu; Lu-Hua Wang; Zong-Mei Zhou; Jian-Rong Dai; Yi-Min Hu; Lu-Jun Zhao

    2004-01-01

    AIM: To compare intensity-modulated radiotherapy (IMRT)with conformal radiotherapy (CRT) by investigating the dose profiles of primary tumors, electively treated regions, and the doses to organs at risk.METHODS: CRT and IMRT plans were designed for five patients with upper esophageal carcinoma. For each patient,target volumes for primary lesions (67.2 Gy) and electively treated regions (50.4 Gy) were predefined. An experienced planner manually designed one CRT plan. Four IMRT plans were generated with the same dose-volume constraints, but with different beam arrangements. Indices including dose distributions, dose volume histograms (DVHs) and conformity index were compared.RESULTS: The plans with three intensity-modulated beams were discarded because the doses to spinal cord were lager than the tolerable dose 45Gy, and the dose on areas near the skin was up to 50Gy. When the number of intensity beams increased to five, IMRT plans were better than CRT plans in terms of the dose conformity and homogeneity of targets and the dose to OARs. The dose distributions changed little when the beam number increased from five to seven and nine.CONCLUSION: IMRT is superior to CRT for the treatment of upper esophageal carcinoma with simultaneous integrated boost (SIB). Five equispaced coplanar intensity-modulated beams can produce desirable dose distributions. The primary tumor can get higher equivalent dose by SIB technique.The SIB-IMRT technique shortens the total treatment time,and is an easier, more efficient, and perhaps a less errorprone way in delivering IMRT.

  7. Hybrid nanocomposite coatings from metal (Mg alloy)-drug deposited onto medical implant by laser adaptive ablation deposition technique

    Serbezov, Valery; Sotirov, Sotir; Serbezov, Svetlin

    2013-03-01

    Drug-eluting medical implants are active implants whose function is to create healing effects. The current requirements for active medical coatings for Drug-eluting medical implants are to be biocompatible, biodegradable, polymer free, mechanically stable and enable a controlled release of one or more drugs and defined degradation. This brings hybrid nanocomposite coatings into focus especially in the field of cardiovascular implants. We studied the properties of Metal (Mg alloy)-Paclitaxel coatings obtained by novel Laser Adaptive Ablation Deposition Technique (LAAD) onto cardiovascular stents from 316 LVM stainless steel material. The morphology and topology of coatings were studied by Bright field / Fluorescence optical microscope and Scanning Electron Microscope (SEM). Comparative measurements were made of the morphology and topology of hybrid, polymer free nanocomposite coatings deposited by LAAD and polymerdrug coatings deposited by classical spray technique. The coatings obtained by LAAD are homogeneous without damages and cracks. Metal nanoparticles with sizes from 40 nm to 230 nm were obtained in drug matrixes. Energy Dispersive X-ray Spectroscopy (EDX) was used for identification of metal nanoparticles presence in hybrid nanocomposites coatings. The new technology opens up possibilities to obtain new hybrid nanocomposite coatings with applications in medicine, pharmacy and biochemistry.

  8. A digital de-modulator using non-I, Q sampling technique

    Techniques utilizing digital I, Q detection using direct sampling for LLRF control of RF cavities are now popular due to advances in Field Programmable Gate Arrays (FPGA) technology. Direct I/Q detection wherein the Cavity pickup signal is sampled at four times the pickup frequency can be realized using a high speed ADC interfaced to the FPGA. However this method suffers from errors due to DC offset in the carrier, nonlinearity in the ADC, clock jitter which generates harmonics that can alias to the frequency of interest. In addition, phase shifts in the cavity due to vibrations, temperature effects can also lead to time dependent errors. In non-IQ sampling, these errors are avoided by shifting the sampling frequency slightly from four times the frequency of interest. This paper discusses the implementation of a demodulator in a FPGA using a non I/Q sampling technique. This technique has been implemented in a FPGA based, high speed, multi-channel, analog input card with a maximum input sampling rate of 1 Giga samples per second (Gsps) per channel. This paper also briefly presents the results of the implemented technique. (author)

  9. 利用自适应编码调制的无线网络控制系统的分析和设计%Analysis and Design of Wireless Networked Control System Utilizing Adaptive Coded Modulation

    杨丽; 郑新平; 龙承念; 罗小元

    2009-01-01

    In this paper, we explore the analysis and design of wireless networked control system (WNCS) utilizing adaptive coded modulation (ACM) schemes, which can improve the energy efficiency and increase data rate over a fading channel. To capture the characteristics of varying rate, interference, and routing in wireless transmission channel, we introduce the concept of equivalent delay (ED). Based on the time-varying network condition, the analytic lower and upper bounds of EDs are given. Whereafter, WNCS is modelled as a discrete-time system with time-varying input delay. Sufficient stabilization condition of the closed-loop WNCS is derived by making use of novel techniques of time-delay system. Finally, the numerical result shows the validity of our proposed control strategies.

  10. Correlation of 3D MR coronary angiography with selective coronary angiography: feasibility of the motion-adapted gating technique

    The aim of this study was to verify the feasibility of a respiratory motion compensation technique (motion-adapted gating, MAG) for visualization of coronary arteries (CA) by correlation with selective coronary angiography (SCA). Fifteen subjects (11 patients, mean age 61.3 years, age range 41-73 years; and 4 healthy volunteers, mean age 32.3 years, age range 31-35 years) were investigated. A Philips Gyroscan ACS-NT was used, operating at 1.5 T, was combined with the PowerTrak 6000 gradient system. An ECG-triggered, respiratory motion-gated 3D turbo field echo sequence was used. The real-time algorithm utilized the concept of k-space weighting in combination with automatic analysis of respiratory motion. The main CA were investigated. Qualitative analysis was performed by three blinded investigators. Visibility was graded on a five-point scale (0=not visualized, 1=insufficient, 2=sufficient, 3=good, 4=excellent). Segments graded 2-4 were defined as adequately visualized. Sixty-two of 88 assessable CA segments in patient, and 22 of 32 in volunteer group were adequately visualized. Visibility of CA was classified as excellent for proximal RCA (avg. 3.6±0.5), good for LM, proximal LAD, proximal LCX, middle RCA and sufficient for middle LAD. Sensitivity, specificity, positive and negative predictive values for coronary MRA in detection of CA stenoses with luminal narrowing ≥50% were 88, 94, 83, and 96%, respectively. Magnetic resonance imaging in combination with MAG has proven to be a promising technique for noninvasive imaging of CA due to good image quality and a patient convenient free-breathing technique. (orig.)

  11. Circadian adaptation to night shift work influences sleep, performance, mood and the autonomic modulation of the heart.

    Philippe Boudreau

    Full Text Available Our aim was to investigate how circadian adaptation to night shift work affects psychomotor performance, sleep, subjective alertness and mood, melatonin levels, and heart rate variability (HRV. Fifteen healthy police officers on patrol working rotating shifts participated to a bright light intervention study with 2 participants studied under two conditions. The participants entered the laboratory for 48 h before and after a series of 7 consecutive night shifts in the field. The nighttime and daytime sleep periods were scheduled during the first and second laboratory visit, respectively. The subjects were considered "adapted" to night shifts if their peak salivary melatonin occurred during their daytime sleep period during the second visit. The sleep duration and quality were comparable between laboratory visits in the adapted group, whereas they were reduced during visit 2 in the non-adapted group. Reaction speed was higher at the end of the waking period during the second laboratory visit in the adapted compared to the non-adapted group. Sleep onset latency (SOL and subjective mood levels were significantly reduced and the LF∶HF ratio during daytime sleep was significantly increased in the non-adapted group compared to the adapted group. Circadian adaptation to night shift work led to better performance, alertness and mood levels, longer daytime sleep, and lower sympathetic dominance during daytime sleep. These results suggest that the degree of circadian adaptation to night shift work is associated to different health indices. Longitudinal studies are required to investigate long-term clinical implications of circadian misalignment to atypical work schedules.

  12. Cosine Modulated and Offset QAM Filter Bank Multicarrier Techniques: A Continuous-Time Prospect

    Behrouz Farhang-Boroujeny

    2010-01-01

    Full Text Available Prior to the discovery of the celebrated orthogonal frequency division multiplexing (OFDM, multicarrier techniques that use analog filter banks were introduced in the 1960s. Moreover, advancements in the design of perfect reconstruction filter banks have led to a number developments in the design of prototype digital filters and polyphase structures for efficient implementations of the filter bank multicarrier (FBMC systems. The main thrust of this paper is to present a tutorial review of the classical works on FBMC systems and show that some of the more recent developments are, in fact, reinventions of multicarrier techniques that have been developed prior of the era of OFDM. We also review the recent novel developments in the design of FBMC systems that are tuned to cope with fast fading wireless channels.

  13. Cosine Modulated and Offset QAM Filter Bank Multicarrier Techniques: A Continuous-Time Prospect

    Farhang-Boroujeny Behrouz

    2010-01-01

    Full Text Available Abstract Prior to the discovery of the celebrated orthogonal frequency division multiplexing (OFDM, multicarrier techniques that use analog filter banks were introduced in the 1960s. Moreover, advancements in the design of perfect reconstruction filter banks have led to a number developments in the design of prototype digital filters and polyphase structures for efficient implementations of the filter bank multicarrier (FBMC systems. The main thrust of this paper is to present a tutorial review of the classical works on FBMC systems and show that some of the more recent developments are, in fact, reinventions of multicarrier techniques that have been developed prior of the era of OFDM. We also review the recent novel developments in the design of FBMC systems that are tuned to cope with fast fading wireless channels.

  14. Analysis of voltage modulation based active damping techniques for small DC-link drive system

    Wang, Dong; Lu, Kaiyuan; Rasmussen, Peter Omand; Máthé, Lászlo; Yang, Feng

    Small DC-link drive system, built with film capacitor in the DC link, may have the advantages of longer lifetime and the possibility to achieve a more compact design of capacitor bank at medium and high power rates. However, it exhibits instability problem, especially when it is fed by a soft grid...... without the requirements of the information of system parameters and operating conditions. Finally, active damping techniques with minimized current magnitude and total duty cycle are discussed, in order to fit various operating conditions. Simulation and experimental results are presented to verify the....... Therefore, active damping techniques are usually needed in order to stabilize the system. This paper firstly describes the essential idea of active damping methods from energy flow point of view. Then a new method named as “virtual positive impedance” method is introduced to ensure the dc-link stability...

  15. Design and Simulation of Symmetric Nanostructures Using Two-beam Modulated Interference Lithography Technique

    Raj, A Alfred Kiruba; Devaprakasam, D

    2013-01-01

    Interferometry lithography is a maturing technology for patterning sub-micron structures in arrays covering large areas. This paper presents a method for the measurement of nanoscale surface patterns produced by two-beam laser interference lithography (LIL). The objective in this study is to simulate and design periodic and quasi-periodic 1D, 2D and 3D nanostructures using two-beam interference technique. We designed and simulated periodic and quasi-periodic structures by two-beam interference patterning using a MATLAB program by varying angle of incidence, wavelength and geometry. The simulated patterns show that the symmetries of the interference maxima depend mostly on the angles of incidence and perturbations of incidents beams. Using this technique, we can achieve potentially high-volume of uniformity, throughput, process control, and repeatability. By varying different input parameters, we have optimized simulated patterns with controlled periodicity, density and aspect ratio also it can be programmed t...

  16. Appraisal of adaptive neuro-fuzzy computing technique for estimating anti-obesity properties of a medicinal plant.

    Kazemipoor, Mahnaz; Hajifaraji, Majid; Radzi, Che Wan Jasimah Bt Wan Mohamed; Shamshirband, Shahaboddin; Petković, Dalibor; Mat Kiah, Miss Laiha

    2015-01-01

    This research examines the precision of an adaptive neuro-fuzzy computing technique in estimating the anti-obesity property of a potent medicinal plant in a clinical dietary intervention. Even though a number of mathematical functions such as SPSS analysis have been proposed for modeling the anti-obesity properties estimation in terms of reduction in body mass index (BMI), body fat percentage, and body weight loss, there are still disadvantages of the models like very demanding in terms of calculation time. Since it is a very crucial problem, in this paper a process was constructed which simulates the anti-obesity activities of caraway (Carum carvi) a traditional medicine on obese women with adaptive neuro-fuzzy inference (ANFIS) method. The ANFIS results are compared with the support vector regression (SVR) results using root-mean-square error (RMSE) and coefficient of determination (R(2)). The experimental results show that an improvement in predictive accuracy and capability of generalization can be achieved by the ANFIS approach. The following statistical characteristics are obtained for BMI loss estimation: RMSE=0.032118 and R(2)=0.9964 in ANFIS testing and RMSE=0.47287 and R(2)=0.361 in SVR testing. For fat loss estimation: RMSE=0.23787 and R(2)=0.8599 in ANFIS testing and RMSE=0.32822 and R(2)=0.7814 in SVR testing. For weight loss estimation: RMSE=0.00000035601 and R(2)=1 in ANFIS testing and RMSE=0.17192 and R(2)=0.6607 in SVR testing. Because of that, it can be applied for practical purposes. PMID:25453384

  17. Application of electro-optic modulation technique for PD monitoring of power transformers

    Hao, L.; Lewin, P L; Tian, Y; Wilkinson, J.S.; Swingler, S G; Sutton, S. J.

    2006-01-01

    Partial discharge (PD) detection is an important technique for assessing the health of high voltage power transformers. A partial discharge signal within an oil-filled power transformer may reach a winding first, then travel along the winding to the bushing core bar. The bushing, acting like a capacitor, can transfer the high frequency components of the partial discharge signal to its tap point. Previous published work [1] has shown that these high frequency components at the bushing tap poin...

  18. A digital driving technique for an 8 b QVGA AMOLED display using modulation

    Jae Hyuk, Jang; Minho, Kwon; Tjandranegara, E.; Kywro, Lee; Byunghoo, Jung

    2009-01-01

    Active-matrix organic LED (AMOLED) is one of the most promising contenders for next-generation displays. However, the VT-shift issue in thin-film transistors (TFT) has to be addressed to enable wide deployment. Voltage programming and current programming are well-known VT-shift-compensation techniques for analog driving. However, they all need more than 4 TFTs per pixel, which increases the panel complexity and de...

  19. Radiosurgery of small skull-base lesions. No advantage for intensity-modulated stereotactic radiosurgery versus conformal arc technique

    Ernst-Stecken, A.; Sauer, R.; Grabenbauer, G. [Dept. of Radiation Therapy and Novalis Shaped Beam Surgery Center, Univ. of Erlangen-Nuremberg, Erlangen (Germany); Lambrecht, U.; Mueller, R. [Dept. of Radiation Therapy and Novalis Shaped Beam Surgery Center, Univ. of Erlangen-Nuremberg, Erlangen (Germany); Div. of Medical Physics, Dept. of Radiation Therapy, Univ. of Erlangen-Nuremberg, Erlangen (Germany); Ganslandt, O.; Fahlbusch, R. [Dept. of Neurosurgery, Univ. of Erlangen-Nuremberg, Erlangen (Germany)

    2005-05-01

    Background and purpose: intensity-modulated stereotactic radiotherapy (IMSRT) has shown the ability to conform the dose to concavities and to better avoid critical organs for large tumors. Given the availability of an electronically driven micro-multileaf collimator, both intensity-modulated stereotactic radiosurgery (IMSRS) and dynamic conformal arc (DCA) technique (DCA) can be performed at the Novalis Shaped Beam Surgery Center, University of Erlangen-Nuremberg, Germany, since 12/2002. This study evaluates both techniques in small skull-base tumors treated with radiosurgery. Material and methods: between 12/2002 and 04/2004, a total of 109 radiosurgical procedures were performed in 77 patients, equally distributed between patients with acoustic neuroma (AN), pituitary adenoma (PA) and meningeoma (M). Six index patients (n = 2 AN, n = 1 PA, n = 3 M) routinely planned for dynamic arc stereotactic radiosurgery were replanned using the IMSRS approach (BrainScan, BrainLAB, Heimstetten, Germany). The RTOG radiosurgery quality assurance guidelines, isodose volumes, doses to organs at risk (OAR), and dose delivery criteria were compared. Results: DCA was superior to IMSRS for homogeneity and coverage. IMSRS could keep the high-dose-irradiated volumes (90% isodose volume) lower than DCA in the PA and AN with very small volumes, but all other lower dose volumes were larger for IMSRS. Dose maxima to OAR were higher for IMSRS. Treatment delivery time for IMSRS would clearly exceed treatment time for DCA by a factor of 2-3. The integral absorbed dose to the brain was much higher in the IMSRS than in the DCA approach (factor 2-3). Conclusion: RTOG radiosurgery guidelines were best met by the DCA rather than IMSRS approach for the treatment of small skull-base lesions. The IMSRS approach will increase the time for planning, dose delivery and integral dose to the brain. Thus, IMSRT techniques are recommended for fractionated stereotactic radiotherapy to larger volumes rather

  20. T regulatory cells: an overview and intervention techniques to modulate allergy outcome

    Kumaraguru Uday

    2009-03-01

    Full Text Available Abstract Dysregulated immune response results in inflammatory symptoms in the respiratory mucosa leading to asthma and allergy in susceptible individuals. The T helper type 2 (Th2 subsets are primarily involved in this disease process. Nevertheless, there is growing evidence in support of T cells with regulatory potential that operates in non-allergic individuals. These regulatory T cells occur naturally are called natural T regulatory cells (nTregs and express the transcription factor Foxp3. They are selected in the thymus and move to the periphery. The CD4 Th cells in the periphery can be induced to become regulatory T cells and hence called induced or adaptive T regulatory cells. These cells can make IL-10 or TGF-b or both, by which they attain most of their suppressive activity. This review gives an overview of the regulatory T cells, their role in allergic diseases and explores possible interventionist approaches to manipulate Tregs for achieving therapeutic goals.

  1. Neutron intensity modulation and time-focusing with integrated Larmor and resonant frequency techniques

    Zhao, Jinkui; Hamilton, William A.; Lee, Sung-Woo; Robertson, J. L.; Crow, Lowell; Kang, Yoon W.

    2015-09-01

    The analysis of neutron diffraction experiments often assumes that neutrons are elastically scattered from the sample. However, there is growing evidence that a significant fraction of the detected neutrons is in fact inelastically scattered, especially from soft materials and aqueous samples. Ignoring these inelastic contributions gives rise to inaccurate experimental results. To date, there has been no simple method with broad applicability for inelastic signal separation in neutron diffraction experiments. Here, we present a simple and robust method that we believe could be suited for this purpose. We use two radio frequency resonant spin flippers integrated with a Larmor precession field to modulate the neutron intensity and to encode the inelastic scattering information into the neutron data. All three components contribute to the spin encoding. The Larmor field serves several additional purposes. Its usage facilitates neutron time-focusing, eliminates the need for stringent magnetic shielding, and allows for compact setups. The scheme is robust, simple, and flexible. We believe that, with further improvements, it has the potential of adding inelastic signal discrimination capabilities to many existing diffraction instruments in the future.

  2. Circadian Adaptation to Night Shift Work Influences Sleep, Performance, Mood and the Autonomic Modulation of the Heart

    Boudreau, Philippe; Dumont, Guy A.; Boivin, Diane B.

    2013-01-01

    Our aim was to investigate how circadian adaptation to night shift work affects psychomotor performance, sleep, subjective alertness and mood, melatonin levels, and heart rate variability (HRV). Fifteen healthy police officers on patrol working rotating shifts participated to a bright light intervention study with 2 participants studied under two conditions. The participants entered the laboratory for 48 h before and after a series of 7 consecutive night shifts in the field. The nighttime and daytime sleep periods were scheduled during the first and second laboratory visit, respectively. The subjects were considered “adapted” to night shifts if their peak salivary melatonin occurred during their daytime sleep period during the second visit. The sleep duration and quality were comparable between laboratory visits in the adapted group, whereas they were reduced during visit 2 in the non-adapted group. Reaction speed was higher at the end of the waking period during the second laboratory visit in the adapted compared to the non-adapted group. Sleep onset latency (SOL) and subjective mood levels were significantly reduced and the LF∶HF ratio during daytime sleep was significantly increased in the non-adapted group compared to the adapted group. Circadian adaptation to night shift work led to better performance, alertness and mood levels, longer daytime sleep, and lower sympathetic dominance during daytime sleep. These results suggest that the degree of circadian adaptation to night shift work is associated to different health indices. Longitudinal studies are required to investigate long-term clinical implications of circadian misalignment to atypical work schedules. PMID:23923024

  3. A miniaturized compact open-loop RFOG with demodulation signal compensation technique to suppress intensity modulation noise

    Ying, Diqing; Mao, Jianmin; Li, Qiang; Jin, Zhonghe

    2016-01-01

    A miniaturized compact open-loop resonator fiber optic gyro (RFOG) prototype with main body size of about 10.4 cm×10.4 cm×5.2 cm is reported, and a demodulation signal compensation technique is proposed, aiming to suppress the drift arising from accompanying intensity modulation induced by semiconductor laser diode (LD). The scheme of how to establish this miniaturized RFOG prototype is specifically stated. The linear relationship between the first-harmonic and second-harmonic demodulated signals respectively for the two counter propagating beams in the resonator is verified by theory and experiment, and based on this relationship, the demodulation signal compensation technique by monitoring the second-harmonic demodulated signal is described in detail. With this compensation technique, the gyro output stability under 1°/s rotation rate is effectively improved from 0.12°/s to 0.03°/s, and especially, an about 0.36°/s peak-to-peak fluctuation due to tuning current reset is significantly suppressed. A long term bias stability of about 4.5°/h in 1 h for such a small-sized RFOG prototype is demonstrated, which is of the same magnitude as that of currently reported large-sized RFOG systems utilizing LD as the laser source as well.

  4. Synchrony between orientation-selective neurons is modulated during adaptation-induced plasticity in cat visual cortex

    Shumikhina Svetlana

    2008-07-01

    Full Text Available Abstract Background Visual neurons respond essentially to luminance variations occurring within their receptive fields. In primary visual cortex, each neuron is a filter for stimulus features such as orientation, motion direction and velocity, with the appropriate combination of features eliciting maximal firing rate. Temporal correlation of spike trains was proposed as a potential code for linking the neuronal responses evoked by various features of a same object. In the present study, synchrony strength was measured between cells following an adaptation protocol (prolonged exposure to a non-preferred stimulus which induce plasticity of neurons' orientation preference. Results Multi-unit activity from area 17 of anesthetized adult cats was recorded. Single cells were sorted out and (1 orientation tuning curves were measured before and following 12 min adaptation and 60 min after adaptation (2 pairwise synchrony was measured by an index that was normalized in relation to the cells' firing rate. We first observed that the prolonged presentation of a non-preferred stimulus produces attractive (58% and repulsive (42% shifts of cell's tuning curves. It follows that the adaptation-induced plasticity leads to changes in preferred orientation difference, i.e. increase or decrease in tuning properties between neurons. We report here that, after adaptation, the neuron pairs that shared closer tuning properties display a significant increase of synchronization. Recovery from adaptation was accompanied by a return to the initial synchrony level. Conclusion We conclude that synchrony reflects the similarity in neurons' response properties, and varies accordingly when these properties change.

  5. Rapid and noncontact photoacoustic tomography imaging system using an interferometer with high-speed phase modulation technique

    We designed, fabricated, and tested a rapid and noncontact photoacoustic tomography (PAT) imaging system using a low-coherence interferometer with high-speed phase modulation technique. Such a rapid and noncontact probing system can greatly decrease the time of imaging. The proposed PAT imaging system is experimentally verified by capturing images of a simulated tissue sample and the blood vessels within the ear flap of a mouse (pinna) in vivo. The axial and lateral resolutions of the system are evaluated at 45 and ∼15 μm, respectively. The imaging depth of the system is 1 mm in a special phantom. Our results show that the proposed system opens a promising way to realize noncontact, real-time PAT

  6. Performance Evaluation of Digital Modulation Techniques in a WCDMA-based Radio-over-Fiber Communication System

    Amanjot Kaur, Jasbir Singh

    2012-06-01

    Full Text Available The demand of mobile communications in the modern world is increasing day by day and subscribers for the mobile communication technologies are growing rapidly. The data transfer rate should be maximum for uninterruptable communication .Therefore, the Radio over fiber system along with wireless communication, is used for the high speed data transfer. This combination will increase the capacity for the cellular base stations to change dynamically and meet the traffic requirements. To better understand the M-ary PSK system, a Simulink-based simulation system is designed for M-ary PSK for M=64 using communication toolbox in Simulink. In this paper we propose the suitability of 64 PSK Digital Modulation Technique for transmission and the results are analyzed on the basis of BER, scatter plot and eye diagram like performance measures.

  7. Rapid and noncontact photoacoustic tomography imaging system using an interferometer with high-speed phase modulation technique

    Liu, Jun [School of Physics and Telecom Engineering, South China Normal University, Guangzhou 510006 (China); Tang, Zhilie; Wu, Yongbo [School of Physics and Telecom Engineering, South China Normal University, Guangzhou 510006 (China); GuangDong Province Key Laboratory of Quantum Engineering and Quantum Materials, South China Normal University, IMOT, Guangzhou 510006 (China); Wang, Yi [School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao 066004 (China)

    2015-04-15

    We designed, fabricated, and tested a rapid and noncontact photoacoustic tomography (PAT) imaging system using a low-coherence interferometer with high-speed phase modulation technique. Such a rapid and noncontact probing system can greatly decrease the time of imaging. The proposed PAT imaging system is experimentally verified by capturing images of a simulated tissue sample and the blood vessels within the ear flap of a mouse (pinna) in vivo. The axial and lateral resolutions of the system are evaluated at 45 and ∼15 μm, respectively. The imaging depth of the system is 1 mm in a special phantom. Our results show that the proposed system opens a promising way to realize noncontact, real-time PAT.

  8. Rapid and noncontact photoacoustic tomography imaging system using an interferometer with high-speed phase modulation technique

    Liu, Jun; Tang, Zhilie; Wu, Yongbo; Wang, Yi

    2015-04-01

    We designed, fabricated, and tested a rapid and noncontact photoacoustic tomography (PAT) imaging system using a low-coherence interferometer with high-speed phase modulation technique. Such a rapid and noncontact probing system can greatly decrease the time of imaging. The proposed PAT imaging system is experimentally verified by capturing images of a simulated tissue sample and the blood vessels within the ear flap of a mouse (pinna) in vivo. The axial and lateral resolutions of the system are evaluated at 45 and ˜15 μm, respectively. The imaging depth of the system is 1 mm in a special phantom. Our results show that the proposed system opens a promising way to realize noncontact, real-time PAT.

  9. IMPLEMENTATION OF SPACE VECTOR PULSE WIDTH MODULATION TECHNIQUE WITH GENETIC ALGORITHM TO OPTIMIZE UNIFIED POWER QUALITY CONDITIONER

    M. Shankar

    2014-01-01

    Full Text Available This study proposes a novel control design of Unified Power Quality Conditioner (UPQC. This design is enabled by a control framework that employs Genetic Algorithm which determines optimum points and angle for filtering and Space Vector Pulse Width Modulation Technique (SVPWM to offer significant flexibility to optimize waveform. In addition the same framework integrates the major functions of the UPQC with ease to unify the treatments of several power quality problems including system harmonics in the supply voltage and load current, sags/swells in the supply voltage, variations in the load demands and poor power factor at the supply side. Simulation studies on a three phase power distribution system are used to verify the performance and implementation of this control design with the UPQC.

  10. Marginal adaptation of class II resin composite restorations using incremental and bulk placement techniques: an ESEM study.

    Idriss, S; Habib, C; Abduljabbar, T; Omar, R

    2003-10-01

    This in vitro study compared marginal gap formation in class II resin composite restorations. Forty caries-free extracted molars were prepared in a standardized manner for class II restoration by one of four methods: bulk- or incrementally-placed light-activated resin composite (Amelogen), and bulk- or incrementally-placed chemically activated composite (Rapidfill). The restored teeth, after finishing and polishing, and thermocycling, were examined using environmental scanning electron microscopy. Marginal gap measurements at predetermined facial and lingual margin sites showed no significant differences between the two sites within any of the groups. Both the light- and the chemically-activated restorations showed no significant differences in mean marginal gap sizes whether they were placed by incremental or bulk techniques. Amelogen restorations placed by both methods had significantly larger margin gaps than those of each of the Rapidfill groups (Peffect on the quality of marginal adaptation, both of the chemically activated resin composite restorations produced significantly smaller marginal gaps than both the bulk- and incrementally-placed light-activated composites. PMID:12974860

  11. Adaptive Data Processing Technique for Lidar-Assisted Control to Bridge the Gap between Lidar Systems and Wind Turbines: Preprint

    Schlipf, David; Raach, Steffen; Haizmann, Florian; Cheng, Po Wen; Fleming, Paul; Scholbrock, Andrew, Krishnamurthy, Raghu; Boquet, Mathieu

    2015-12-14

    This paper presents first steps toward an adaptive lidar data processing technique crucial for lidar-assisted control in wind turbines. The prediction time and the quality of the wind preview from lidar measurements depend on several factors and are not constant. If the data processing is not continually adjusted, the benefit of lidar-assisted control cannot be fully exploited, or can even result in harmful control action. An online analysis of the lidar and turbine data are necessary to continually reassess the prediction time and lidar data quality. In this work, a structured process to develop an analysis tool for the prediction time and a new hardware setup for lidar-assisted control are presented. The tool consists of an online estimation of the rotor effective wind speed from lidar and turbine data and the implementation of an online cross correlation to determine the time shift between both signals. Further, initial results from an ongoing campaign in which this system was employed for providing lidar preview for feed-forward pitch control are presented.

  12. A comparison between single exponential smoothing (SES, double exponential smoothing (DES, holt’s (brown and adaptive response rate exponential smoothing (ARRES techniques in forecasting Malaysia population

    Ahmad Nazim Aimran

    2014-09-01

    Full Text Available This research develops techniques which are helpful in forecasting univariate time series data. The techniques used in this study are Single Exponential Smoothing (SES, Double Exponential Smoothing (DES, Holt’s (Brown and Adaptive Response Rate Exponential Smoothing (ARRES Techniques. For the purpose of this study, secondary data of Malaysia Population covering the period 1957 up to 2013 was obtained from the Department of Statistics Malaysia. From the result obtained, Holt’s method was found to be the best method to forecast the Malaysia population since it produces the lowest Mean Square Error (MSE value which is 38,273.3 compared to 210,480.29 for SES, 38,827.7 for DEB and 209,835.8 for ARRES techniques. Keywords: Univariate, Forecasting, Single Exponential Smoothing, Double Exponential Smoothing, And Adaptive Response Rate Exponential Smoothing, Holt’s (Brown.

  13. On-line monitoring of solar cell module production by ellipsometry technique

    Non-destructive analyzing tools are needed at all stages of thin film photovoltaic (PV) development, and on production lines. In thin film PV, layer thicknesses, micro-structure, composition, layer optical properties, and their uniformity (because each elementary cell is connected electrically in series within a big panel) serve as an important starting point in the evaluation of the performance of the cell or module. An important focus is to express the dielectric functions of each component material in terms of a handful of wavelength independent parameters whose variation can cover all process variants of that material. With the resulting database, spectroscopic ellipsometry coupled with multilayer analysis can be developed for on-line point-by-point mapping and on-line line-by-line imaging. This work tries to review the investigations of different types of PV-layers (anti-reflective coating, transparent-conductive oxide (TCO), multi-diode-structure, absorber and window layers) showing the existing dielectric function databases for the thin film components of CdTe, CuInGaSe2, thin Si, and TCO layers. Off-line point-by-point mapping can be effective for characterization of non-uniformities in full scale PV panels in developing labs but it is slow in the on-line mode when only 15 points can be obtained (within 1 min) as a 120 cm long panel moves by the mapping station. In the last years [M. Fried et al., Thin Solid Films 519, 2730 (2011)], instrumentation was developed that provides a line image of spectroscopic ellipsometry (wl = 350–1000 nm) data. Up to now a single 30 point line image can be collected in 10 s over a 15 cm width of PV material. This year we are building a 30 and a 60 cm width expanded beam ellipsometer the speed of which will be increased by 10 ×. Then 1800 points can be mapped in a 1 min traverse of a 60 ∗ 120 cm PV panel or flexible roll-to-roll substrate. - Highlights: • Instrumentation developed provides a line image of spectroscopic

  14. SU-E-T-489: Plan Comparisons of Re-Irradiation Treatment of Three Intensity Modulated Techniques

    Lian, J; Tang, X [University North Carolina, Chapel Hill, NC (United States); Liu, R [Robert Boissoneault Oncology Inst., Ocala, FL (United States)

    2014-06-01

    Purpose: There have been controversial reports on the comparison of dosimetric quality of TomoTherapy (Tomo), VMAT and IMRT. One of the main reasons is the sampled cases are often not dosimetrically challenging enough to test the limit of optimization/delivery modalities. We chose difficult re-irradiation cases when certain organ at risk (OAR) requires extremely low dose to examine the ability of OAR sparing of three main intensity modulated techniques. Methods: Three previous treated patients with disease site on head and neck (HN), brain and lung are planned for reirradiation treatment. The Tomo planning used jaw 2.5cm and pitch 0.3. VMAT and IMRT were planned on Pinnacle for a Varian 21iX Linac with MLC leaf width 5mm. VMAT plan used 2 Arcs and IMRT plan had beams 11–13. The dosimetric endpoints and treatment time were compared for each technique of each patient. Results: Plans of three techniques cover PTV similarly. The HN case requires PTV dose 60Gy but to limit dose of cord which is 8mm away <12Gy. The cord dose of Tomo, VMAT and IMRT plan is 11.6Gy, 11.3Gy and 11.0Gy, respectively. The brain case has PTV prescription 50.4 Gy while requiring the dose of brainstem < 28Gy. Tomo, VMAT and IMRT plan generate brainstem dose 27.6Gy, 27.6Gy and 27.1Gy respectively. For the lung case, PTV was prescribed 42.5Gy but cord dose constraint was 22.5Gy. The cord dose is optimized to 22.3Gy, 20.8Gy and 21.4Gy by Tomo, VMAT and IMRT, respectively. The delivery time if normalized to Tomo is 47.0%/145.6% (VMAT/IMRT), 33.3%/106.3% and 74.1%/245.4% for HN, brain and lung case, respectively. Conclusion: Difficult re-irradiation cases were used to test the limit of three intensity modulated techniques. Tomo, VMAT and IMRT show similar dosimetry while VMAT is the most efficient one and IMRT is the least.

  15. SU-E-T-489: Plan Comparisons of Re-Irradiation Treatment of Three Intensity Modulated Techniques

    Purpose: There have been controversial reports on the comparison of dosimetric quality of TomoTherapy (Tomo), VMAT and IMRT. One of the main reasons is the sampled cases are often not dosimetrically challenging enough to test the limit of optimization/delivery modalities. We chose difficult re-irradiation cases when certain organ at risk (OAR) requires extremely low dose to examine the ability of OAR sparing of three main intensity modulated techniques. Methods: Three previous treated patients with disease site on head and neck (HN), brain and lung are planned for reirradiation treatment. The Tomo planning used jaw 2.5cm and pitch 0.3. VMAT and IMRT were planned on Pinnacle for a Varian 21iX Linac with MLC leaf width 5mm. VMAT plan used 2 Arcs and IMRT plan had beams 11–13. The dosimetric endpoints and treatment time were compared for each technique of each patient. Results: Plans of three techniques cover PTV similarly. The HN case requires PTV dose 60Gy but to limit dose of cord which is 8mm away <12Gy. The cord dose of Tomo, VMAT and IMRT plan is 11.6Gy, 11.3Gy and 11.0Gy, respectively. The brain case has PTV prescription 50.4 Gy while requiring the dose of brainstem < 28Gy. Tomo, VMAT and IMRT plan generate brainstem dose 27.6Gy, 27.6Gy and 27.1Gy respectively. For the lung case, PTV was prescribed 42.5Gy but cord dose constraint was 22.5Gy. The cord dose is optimized to 22.3Gy, 20.8Gy and 21.4Gy by Tomo, VMAT and IMRT, respectively. The delivery time if normalized to Tomo is 47.0%/145.6% (VMAT/IMRT), 33.3%/106.3% and 74.1%/245.4% for HN, brain and lung case, respectively. Conclusion: Difficult re-irradiation cases were used to test the limit of three intensity modulated techniques. Tomo, VMAT and IMRT show similar dosimetry while VMAT is the most efficient one and IMRT is the least

  16. PAPR reduction for OFDM systems with adaptive modulation%利用自适应调制进行OFDM系统PAPR抑制

    胡登鹏; 石峰; 王世练; 张尔扬

    2012-01-01

    根据相同的信息比特采用不同调制样式时所得的正交频分复用( OFDM)信号的峰均功率比(PAPR)不同,提出了一种利用自适应调制进行OFDM系统PAPR抑制的算法,并设计了利用该算法的OFDM系统.算法通过设定一个可选调制样式集合,改变发端信息比特的调制样式,选择具有最小PAPR值的OFDM信号作为传输的OFDM信号,从而使整个系统的PAPR得到抑制.在接收端,通过对OFDM符号的调制样式进行识别,完成对调制信息解调.由于算法不需要传输需严格保护的边带信息,系统具有较强的可靠性和抗干扰能力.仿真结果表明,利用自适应调制可有效地进行OFDM系统PAPR抑制;同已有算法相比,在多径信道下,利用该算法的OFDM系统的误码率性能总体上较好.%This paper proposes a PAPR reduction algorithm for OFDM systems with adaptive modulation, which is based on the fact that an OFDM symbol has different PAPR when its modulation type is changed, and designs an OFDM system. A group of modulation type is set to be the candidate and the OFDM symbol' s modulation type is changed according to the group. The one with the minimal peak power is selected as the output signal. In receiver, the information bit can be demodulated after the modulation type detection. As there is no side information which should be strictly protected, the system is more reliable and robust. Simulation results show that it is effective for PAPR reduction with adaptive modulation in OFDM systems, and the proposed algorithm's system has better bit error ratio performances than previously algorithms as a whole.

  17. Marginal adaptation of mineral trioxide aggregate (MTA to root dentin surface with orthograde/retrograde application techniques: A microcomputed tomographic analysis

    Khalid Al Fouzan

    2015-01-01

    Full Text Available Background: Achieving a good apical seal for root canals is known to be associated with good mineral trioxide aggregate (MTA adaptation to dentin. Aims: This study aims to compare the marginal adaptation of MTA with root dentin between orthograde and retrograde application techniques using microcomputed tomography (micro-CT analysis. Settings and Design: Fifty-two single-rooted human teeth were divided into four equal groups: (Group 1 Retrograde MTA (RMTA, (Group 2 Orthograde MTA (OMTA, (Group 3 Etched RMTA (ERMTA, and (Group 4 Etched OMTA (EOMTA. Materials and Methods: For Group 1, 3-mm retrograde cavities were prepared and filled with MTA. For Group 2, the apical 6 mm of the canals were filled with MTA and sealed with sealer cement and warm gutta-percha. In Groups 3 and 4, canals were treated the same as Groups 1 and 2, respectively, except that before placing the MTA, canals were irrigated with 17% ethylenediaminetetraacetic acid (EDTA. After 48 hours, all the teeth were analyzed using a micro-CT scanner. Statistical Analysis: Mean dentin-MTA contact and the mean length and width of each gap was analysed using one-way analysis of variance (ANOVA. Statistical significance was set at an α level of 5%. Results: No significant difference in gap volumes was observed in the dentin-MTA adaptation in both orthograde and retrograde application techniques. However, significant difference in the gap volumes was observed between RMTA and ERMTA (P = 0.045. Etching significantly improved the MTA-Dentin adaptation (P < 0.05. The type of application technique did not significantly improve the dentin-MTA adaptation, instead with the use of 17% EDTA, a significant improvement could be achieved. Conclusion: Within the limitations of the present study, it concludes that MTA adaptation to dentin tooth structure is not significantly different between an orthograde and retrograde approach. However, the use of EDTA significantly improved the MTA-Dentin adaptation.

  18. Dynamic Test Case Design Scenario and analysis of Module Testing Using Manual vs. Automated Technique

    Er. RAJENDER KUMAR

    2012-06-01

    Full Text Available Software can be tested either manually or automatically.The two approaches are complementary: automated testingcan perform a huge number of tests in short time or period,whereas manual testing uses the knowledge of the testingengineer to target testing to the parts of the system that areassumed to be more error-prone. Despite this contemporary,tools for manual and automatic testing are usually different,leading to decreased productivity and reliability of thetesting process. AutoTest is a testing tool that provides a“best of both worlds” strategy: it integrates developers’ testcases into an automated process of systematic contractdriventesting. This allows it to combine the benefits of bothapproaches while keeping a simple interface, and to treat thetwo types of tests in a unified fashion: evaluation of resultsis the same, coverage measures are added up, and both typesof tests can be saved in the same format. The objective ofthis paper is to discuss the Importance of Automation toolwith associate to software testing techniques in softwareengineering. In this paper we provide introduction ofsoftware testing and describe the CASE tools. The solutionof this problem leads to the new approach of softwaredevelopment known as software testing in the IT world.Software Test Automation is the process of automating thesteps of manual test cases using an automation tool or utilityto shorten the testing life cycle with respect to time.

  19. Advancement of gamma-spectroscopic measuring systems of BfS and adaptation of measuring and evaluation techniques to the requirements of emergency response. Final report

    The final report on advancement of gamma-spectroscopic measuring systems of BfS and adaptation of measuring and evaluation techniques to the requirements of emergency response covers the following issues: results of literature search, calculation of geometric factors, calibration for the helicopter, combination of geometric factors and calibration, measuring flights, detection limit and performance optimization, identification of activities in the air volume.

  20. Peripheral dose measurements in cervical cancer radiotherapy: a comparison of volumetric modulated arc therapy and step-and-shoot IMRT techniques

    Jia, Ming X; ZHANG, XU; Yin, Ce; Feng, Ge; Li, Na; Gao, Song; Liu, Da W

    2014-01-01

    Purpose The aim of this study was to investigate the peripheral doses resulting from volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT) techniques in cervical cancer radiotherapy. Methods Nine patients with cervical cancer had treatment planned with both VMAT and IMRT. A specially designed phantom was used for this study, with ion chambers placed at interest points approximating the position of the breast, thyroid, and lens. The peripheral doses at the phantom...

  1. Adaptation and Evaluation of Online Self-learning Modules to Teach Critical Appraisal and Evidence-Based Practice in Nursing: An International Collaboration.

    Gagnon, Johanne; Gagnon, Marie-Pierre; Buteau, Rose-Anne; Azizah, Ginette Mbourou; Jetté, Sylvie; Lampron, Amélie; Simonyan, David; Asua, José; Reviriego, Eva

    2015-07-01

    Healthcare professionals need to update their knowledge and acquire skills to continually inform their practice based on scientific evidence. This study was designed to evaluate online self-learning modules on critical appraisal skills to promote the use of research in clinical practice among nurses from Quebec (Canada) and the Basque Country (Spain). The teaching material was developed in Quebec and adapted to the Basque Country as part of an international collaboration project. A prospective pre-post study was conducted with 36 nurses from Quebec and 47 from the Basque Country. Assessment comprised the administration of questionnaires before and after the course in order to explore the main intervention outcomes: knowledge acquisition and self-learning readiness. Satisfaction was also measured at the end of the course. Two of the three research hypotheses were confirmed: (1) participants significantly improved their overall knowledge score after the educational intervention; and (2) they were, in general, satisfied with the course, giving it a rating of seven out of 10. Participants also reported a greater readiness for self-directed learning after the course, but this result was not significant in Quebec. The study provides unique knowledge on the cultural adaptation of online self-learning modules for teaching nurses about critical appraisal skills and evidence-based practice. PMID:25978538

  2. MODEL-BASED IDENTIFICATION AND ADAPTIVE CONTROL OF THE CORE MODULE IN A TYPICAL CELL CYCLE PATHWAY VIA NETWORK AND SYSTEM CONTROL THEORIES

    BINHUA TANG; LI HE; QING JING; BAIRONG SHEN

    2009-01-01

    The loss of cell cycle control is often associated with cancers and other different diseases. With the accumulation of omics data, the network for molecule interactions in the cell cycle process will become much clearer. The identification of the crucial modules in a giant network and investigation of inherent control relations are very important to the understanding of the molecular mechanisms of diseases for new drug design. The paper proposes novel techniques in analyzing such core regulat...

  3. Optical UWB pulse generator using an N tap microwave photonic filter and phase inversion adaptable to different pulse modulation formats.

    Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José

    2009-03-30

    We propose theoretically and demonstrate experimentally an optical architecture for flexible Ultra-Wideband pulse generation. It is based on an N-tap reconfigurable microwave photonic filter fed by a laser array by using phase inversion in a Mach-Zehnder modulator. Since a large number of positive and negative coefficients can be easily implemented, UWB pulses fitted to the FCC mask requirements can be generated. As an example, a four tap pulse generator is experimentally demonstrated which complies with the FCC regulation. The proposed pulse generator allows different pulse modulation formats since the amplitude, polarity and time delay of generated pulse is controlled. PMID:19333263

  4. Intensity modulation in breast radiotherapy: Development of an innovative field-in-field technique at Institut Gustave-Roussy

    Purpose. - To assess the potential dosimetric gain of pre-segmentation modulated radiotherapy (OAPS, DosiSoftTM) of breast, compared to routine 3D conformal radiotherapy. Patients and methods. - Twenty patients treated with conservative surgery for breast cancer (9 right and 11 left sided) with various breast volume (median 537 cm3; range [100-1049 cm3]) have been selected. For each patient, we have delineated a breast volume and a compensation volume (target volumes), as well as organs at risk (lungs and heart). Two treatment plans have been generated: one using the routine 3D conformal technique and the other with the pre-segmentation algorithm of DosiSoftTM (OAPS). The dose distribution were analyzed using the conformity index for target volumes, mean dose and V 30 Gy for the heart, and mean dose, V 20 Gy and V 30 Gy for lungs. Results. - Over the 20 patients, the conformity index increased from 0.897 with routine technique to 0.978 with OAPS (P TM) is an original method of segmentation of breast. It is automatic, fast and easy, and is able to increase the conformity index, while sparing organ at risk. (authors)

  5. Input-Feedforward Two-Path Band-Pass Delta-Sigma Modulator Based on Horizontal or Vertical Opamp Sharing Technique

    Waki, Naoya; Sato, Hiroki; Hyogo, Akira; Sekine, Keitaro

    In this paper, horizontal (where an opamp is shared in two adjacent stages) and vertical (where an opamp is shared across two paths) opamp sharing techniques for a two-path band-pass (BP) ΔΣ modulator are described, and input-feedforward two-path fourth-order BP ΔΣ modulators that have only two opamps are proposed. The proposed modulators are based on the horizontal or vertical opamp sharing technique. They can be realized with both a summation circuit using a switched capacitor (SC) network and a second-order high-pass filter (HPF) with a horizontal shared opamp or a double-sampling first-order HPF with a vertical shared opamp, which are based on an SC first-order HPF with an opamp. These techniques can reduce the number of opamps with no additional component and the chip area as well as realize lower power consumption.

  6. Variable Delay With Directly-Modulated R-SOA and Optical Filters for Adaptive Antenna Radio-Fiber Access

    Prince, Kamau; Presi, Marco; Chiuchiarelli, Andrea;

    2009-01-01

    on a directly-modulated reflective emiconductor amplifier (R-SOA) and exploits the interplay between transmission-line dispersion and tunable optical filtering to achieve flexible true time delay, with $2pi$ beam steering at the different antennas. The system was characterized, then successfully...

  7. Tuning macro-twinned domain sizes and the b-variants content of the adaptive 14-modulated martensite in epitaxial Ni-Mn-Ga films by co-sputtering

    Tillier, Jérémy; Bourgault, Daniel; Odier, Philippe; Ortega, Luc; Pairis, Sébastien; Fruchart, Olivier; Caillault, Nathalie; Carbone, Laurent

    2011-01-01

    International audience In order to obtain modulated-martensite in our epitaxial Ni-Mn-Ga films, we have tuned the composition by using a co-sputtering process. Here we present how the composition affects the variant distribution of the 14-modulated martensite at room temperature. The nature of such modulated-martensites is still strongly debated for magnetic shape memory alloys. It has been very recently demonstrated that the modulated-martensites in Ni-Mn-Ga are adaptive phases. The resul...

  8. SU-E-T-138: Dosimetric Verification For Volumetric Modulated Arc Therapy Cranio-Spinal Irradiation Technique

    Purpose: Dosimetric feasibility of cranio-spinal irradiation with volumetric modulated arc therapy (VMAT-CSI) technique in terms of dose distribution accuracy was investigated using a humanlike phantom. Methods: The OARs and PTV volumes for the Rando phantom were generated on supine CT images. Eclipse (version 8.6) TPS with AAA algorithm was used to create the treatment plan with VMAT-CSI technique. RapidArc plan consisted of cranial, upper spinal (US) and lower spinal (LS) regions that were optimized in the same plan. US field was overlapped by 3cm with cranial and LS fields. Three partial arcs for cranium and 1 full arc for each US and LS region were used. The VMAT-CSI dose distribution inside the Rando phantom was measured with thermoluminescent detectors (TLD) and film dosimetry, and was compared to the calculated doses of field junctions, target and OARs. TLDs were placed at 24 positions throughout the phantom. The measured TLD doses were compared to the calculated point doses. Planar doses for field junctions were verified with Gafchromic films. Films were analyzed in PTW Verisoft application software using gamma analysis method with the 4 mm distance to agreement (DTA) and 4% dose agreement criteria. Results: TLD readings demonstrated accurate dose delivery, with a median dose difference of -0.3% (range: -8% and 12%) when compared with calculated doses for the areas inside the treatment portal. The maximum dose difference was 12% higher in testicals that are outside the treatment region and 8% lower in lungs where the heterogeinity was higher. All planar dose verifications for field junctions passed the gamma analysis and measured planar dose distributions demonstrated average 97% agreement with calculated doses. Conclusion: The dosimetric data verified with TLD and film dosimetry shows that VMAT-CSI technique provides accurate dose distribution and can be delivered safely

  9. Radiation dose considerations by intra-individual Monte Carlo simulations in dual source spiral coronary computed tomography angiography with electrocardiogram-triggered tube current modulation and adaptive pitch

    May, Matthias S.; Kuettner, Axel; Lell, Michael M.; Wuest, Wolfgang; Scharf, Michael; Uder, Michael [University of Erlangen, Department of Radiology, Erlangen (Germany); Deak, Paul; Kalender, Willi A. [University of Erlangen, Department of Medical Physics, Erlangen (Germany); Keller, Andrea K.; Haeberle, Lothar [University of Erlangen, Department of Medical Informatics, Biometry and Epidemiology, Erlangen (Germany); Achenbach, Stephan; Seltmann, Martin [University of Erlangen, Department of Cardiology, Erlangen (Germany)

    2012-03-15

    To evaluate radiation dose levels in patients undergoing spiral coronary computed tomography angiography (CTA) on a dual-source system in clinical routine. Coronary CTA was performed for 56 patients with electrocardiogram-triggered tube current modulation (TCM) and heart-rate (HR) dependent pitch adaptation. Individual Monte Carlo (MC) simulations were performed for dose assessment. Retrospective simulations with constant tube current (CTC) served as reference. Lung tissue was segmented and used for organ and effective dose (ED) calculation. Estimates for mean relative ED was 7.1 {+-} 2.1 mSv/100 mAs for TCM and 12.5 {+-} 5.3 mSv/100 mAs for CTC (P < 0.001). Relative dose reduction at low HR ({<=}60 bpm) was highest (49 {+-} 5%) compared to intermediate (60-70 bpm, 33 {+-} 12%) and high HR (>70 bpm, 29 {+-} 12%). However lowest ED is achieved at high HR (5.2 {+-} 1.5 mSv/100 mAs), compared with intermediate (6.7 {+-} 1.6 mSv/100 mAs) and low (8.3 {+-} 2.1 mSv/100 mAs) HR when automated pitch adaptation is applied. Radiation dose savings up to 52% are achievable by TCM at low and regular HR. However lowest ED is attained at high HR by pitch adaptation despite inferior radiation dose reduction by TCM. circle Monte Carlo simulations allow for individual radiation dose calculations. (orig.)

  10. Radiation dose considerations by intra-individual Monte Carlo simulations in dual source spiral coronary computed tomography angiography with electrocardiogram-triggered tube current modulation and adaptive pitch

    To evaluate radiation dose levels in patients undergoing spiral coronary computed tomography angiography (CTA) on a dual-source system in clinical routine. Coronary CTA was performed for 56 patients with electrocardiogram-triggered tube current modulation (TCM) and heart-rate (HR) dependent pitch adaptation. Individual Monte Carlo (MC) simulations were performed for dose assessment. Retrospective simulations with constant tube current (CTC) served as reference. Lung tissue was segmented and used for organ and effective dose (ED) calculation. Estimates for mean relative ED was 7.1 ± 2.1 mSv/100 mAs for TCM and 12.5 ± 5.3 mSv/100 mAs for CTC (P 70 bpm, 29 ± 12%). However lowest ED is achieved at high HR (5.2 ± 1.5 mSv/100 mAs), compared with intermediate (6.7 ± 1.6 mSv/100 mAs) and low (8.3 ± 2.1 mSv/100 mAs) HR when automated pitch adaptation is applied. Radiation dose savings up to 52% are achievable by TCM at low and regular HR. However lowest ED is attained at high HR by pitch adaptation despite inferior radiation dose reduction by TCM. circle Monte Carlo simulations allow for individual radiation dose calculations. (orig.)

  11. Radiological and Clinical Pneumonitis After Stereotactic Lung Radiotherapy: A Matched Analysis of Three-Dimensional Conformal and Volumetric-modulated Arc Therapy Techniques

    Purpose: Lung fibrosis is common after stereotactic body radiotherapy (SBRT) for lung tumors, but the influence of treatment technique on rates of clinical and radiological pneumonitis is not well described. After implementing volumetric modulated arc therapy (RapidArc [RA]; Varian Medical Systems, Palo Alto, CA) for SBRT, we scored the early pulmonary changes seen with arc and conventional three-dimensional SBRT (3D-CRT). Methods and Materials: Twenty-five SBRT patients treated with RA were matched 1:2 with 50 SBRT patients treated with 3D-CRT. Dose fractionations were based on a risk-adapted strategy. Clinical pneumonitis was scored using Common Terminology Criteria for Adverse Events version 3.0. Acute radiological changes 3 months posttreatment were scored by three blinded observers. Relationships among treatment type, baseline factors, and outcomes were assessed using Spearman's correlation, Cochran-Mantel-Haenszel tests, and logistic regression. Results: The RA and 3D-CRT groups were well matched. Forty-three patients (57%) had radiological pneumonitis 3 months after treatment. Twenty-eight patients (37%) had computed tomography (CT) findings of patchy or diffuse consolidation, and 15 patients (20%) had ground-glass opacities only. Clinical pneumonitis was uncommon, and no differences were seen between 3D-CRT vs. RA patients in rates of grade 2/3 clinical pneumonitis (6% vs. 4%, respectively; p = 0.99), moderate/severe radiological changes (24% vs. 36%, respectively, p = 0.28), or patterns of CT changes (p = 0.47). Radiological severity scores were associated with larger planning target volumes (p = 0.09) and extended fractionation (p = 0.03). Conclusions: Radiological changes after lung SBRT are common with both approaches, but no differences in early clinical or radiological findings were observed after RA. Longer follow-up will be required to exclude late changes.

  12. Estimation of breast dose saving potential using a breast positioning technique for organ-based tube current modulated CT

    Fu, Wanyi; Tian, Xiaoyu; Sturgeon, Gregory; Agasthya, Greeshma; Segars, William Paul; Goodsitt, Mitchell M.; Kazerooni, Ella A.; Samei, Ehsan

    2016-04-01

    In thoracic CT, organ-based tube current modulation (OTCM) reduces breast dose by lowering the tube current in the 120° anterior dose reduction zone of patients. However, in practice the breasts usually expand to an angle larger than the dose reduction zone. This work aims to simulate a breast positioning technique (BPT) to constrain the breast tissue to within the dose reduction zone for OTCM and to evaluate the corresponding potential reduction in breast dose. Thirteen female anthropomorphic computational phantoms were studied (age range: 27-65 y.o., weight range: 52-105.8 kg). Each phantom was modeled in the supine position with and without application of the BPT. Attenuation-based tube current (ATCM, reference mA) was generated by a ray-tracing program, taking into account the patient attenuation change in the longitudinal and angular plane (CAREDose4D, Siemens Healthcare). OTCM was generated by reducing the mA to 20% between +/- 60° anterior of the patient and increasing the mA in the remaining projections correspondingly (X-CARE, Siemens Healthcare) to maintain the mean tube current. Breast tissue dose was estimated using a validated Monte Carlo program for a commercial scanner (SOMATOM Definition Flash, Siemens Healthcare). Compared to standard tube current modulation, breast dose was significantly reduced using OTCM by 19.8+/-4.7%. With the BPT, breast dose was reduced by an additional 20.4+/-6.5% to 37.1+/-6.9%, using the same CTDIvol. BPT was more effective for phantoms simulating women with larger breasts with the average breast dose reduction of 30.2%, 39.2%, and 49.2% from OTCMBP to ATCM, using the same CTDIvol for phantoms with 0.5, 1.5, and 2.5 kg breasts, respectively. This study shows that a specially designed BPT improves the effectiveness of OTCM.

  13. Regulatory modulation of the T-box gene Tbx5 links development, evolution, and adaptation of the sternum

    Bickley, Sorrel R. B.; Logan, Malcolm P. O.

    2014-01-01

    The fin-to-limb transition and acquisition of sterna were critical steps in the evolution of tetrapods, but despite the importance of the sternum in enabling quadrupedal locomotion and avian flight, the mechanisms controlling acquisition and evolutionary adaptation of sterna are not understood. Furthermore, the mechanisms that underlie sternum development and sternal defects are not known. We describe T-box transcription factor gene Tbx5 function in sternum formation, how disruption of TBX5 c...

  14. Splenectomy inhibits non-small cell lung cancer growth by modulating anti-tumor adaptive and innate immune response

    Levy, Liran; Mishalian, Inbal; Bayuch, Rachel; Zolotarov, Lida; Michaeli, Janna; Fridlender, Zvi G.

    2015-01-01

    It has been shown that inhibitors of the immune system reside in the spleen and inhibit the endogenous antitumor effects of the immune system. We hypothesized that splenectomy would inhibit the growth of relatively large non-small lung cancer (NSCLC) tumors by modulating the systemic inhibition of the immune system, and in particular Myeloid Derived Suppressor Cells (MDSC). The effect of splenectomy was evaluated in several murine lung cancer models. We found that splenectomy reduces tumor gr...

  15. Dosimetric advantages of a “butterfly” technique for intensity-modulated radiation therapy for young female patients with mediastinal Hodgkin’s lymphoma

    Voong, Khinh Ranh; McSpadden, Kelli; Pinnix, Chelsea C.; Shihadeh, Ferial; Reed, Valerie; Salehpour, Mohammad R.; Arzu, Isidora; Wang, He; Hodgson, David; Garcia, John; Aristophanous, Michalis; Dabaja, Bouthaina S

    2014-01-01

    Purpose High cure rates for Hodgkin’s lymphoma must be balanced with long-term treatment-related toxicity. Here we report an intensity-modulated radiation therapy (IMRT) technique that achieves adequate target coverage for mediastinal disease while minimizing high- and low-dose exposure of critical organs. Methods and materials Treatment plans for IMRT and conventional anteroposterior-posteroanterior (AP-PA) techniques, with comparable coverage of the planning target volume (PTV), were genera...

  16. Sampling modulation technique in radio-frequency helium glow discharge emission source by use of pulsed laser ablation.

    Naeem, Tariq Mahmood; Matsuta, Hideyuki; Wagatsuma, Kazuaki

    2004-05-01

    An emission excitation source comprising a high-frequency diode-pumped Q-switched Nd:YAG laser and a radio-frequency powered glow discharge lamp is proposed. In this system sample atoms ablated by the laser irradiation are introduced into the lamp chamber and subsequently excited by the helium glow discharge plasma. The pulsed operation of the laser can produce a cyclic variation in the emission intensities of the sample atoms whereas the plasma gas species emit the radiation continuously. The salient feature of the proposed technique is the selective detection of the laser modulation signal from the rest of the continuous background emissions, which can be achieved with the phase sensitive detection of the lock-in amplifier. The arrangement may be used to estimate the emission intensity of the laser ablated atom, free from the interference of other species present in the plasma. The experiments were conducted with a 13.56 MHz radio-frequency (rf) generator operated at 80 W power to produce plasma and the laser at a wavelength of 1064 nm (pulse duration:34 ns, repetition rate:7 kHz and average pulse energy of about 0.36 mJ) was employed for sample ablation. The measurements resulted in almost complete removal of nitrogen molecular bands (N(2)(+) 391.44 nm). Considerable reduction (about 75%) in the emission intensity of a carbon atomic line (C I 193.03 nm) was also observed. PMID:15034707

  17. A method of simulating dynamic multileaf collimators using Monte Carlo techniques for intensity-modulated radiation therapy

    A method of modelling the dynamic motion of multileaf collimators (MLCs) for intensity-modulated radiation therapy (IMRT) was developed and implemented into the Monte Carlo simulation. The simulation of the dynamic MLCs (DMLCs) was based on randomizing leaf positions during a simulation so that the number of particle histories being simulated for each possible leaf position was proportional to the monitor units delivered to that position. This approach was incorporated into an EGS4 Monte Carlo program, and was evaluated in simulating the DMLCs for Varian accelerators (Varian Medical Systems, Palo Alto, CA, USA). The MU index of each segment, which was specified in the DMLC-control data, was used to compute the cumulative probability distribution function (CPDF) for the leaf positions. This CPDF was then used to sample the leaf positions during a real-time simulation, which allowed for either the step-shoot or sweeping-leaf motion in the beam delivery. Dose intensity maps for IMRT fields were computed using the above Monte Carlo method, with its accuracy verified by film measurements. The DMLC simulation improved the operational efficiency by eliminating the need to simulate multiple segments individually. More importantly, the dynamic motion of the leaves could be simulated more faithfully by using the above leaf-position sampling technique in the Monte Carlo simulation. (author)

  18. Scanning microphotolysis: a new photobleaching technique based on fast intensity modulation of a scanned laser beam and confocal imaging.

    Wedekind, P; Kubitscheck, U; Peters, R

    1994-10-01

    The fluorescence photobleaching method has been widely used to study molecular transport in single living cells and other microsystems while confocal microscopy has opened new avenues to high-resolution, three-dimensional imaging. A new technique, scanning microphotolysis (Scamp), combines the potential of photobleaching, beam scanning and confocal imaging. A confocal scanning laser microscope was equipped with a sufficiently powerful laser and a novel device, the 'Scamper'. This consisted essentially of a filter changer, an acousto-optical modulator (AOM) and a computer. The computer was programmed to activate the AOM during scanning according to a freely defined image mask. As a result, almost any desired pattern could be bleached ('written') into fluorescent samples at high definition and then imaged ('read') at non-bleaching conditions, employing full confocal resolution. Furthermore, molecular transport could be followed by imaging the dissipation of bleach patterns. Experiments with living cells concerning dynamic processes in cytoskeletal filaments and the lateral mobility of membrane lipids suggest a wide range of potential biological applications. Thus, Scamp offers new possibilities for the optical manipulation and analysis of both technical and biological microsystems. PMID:7799426

  19. Residual stress in a laser welded EUROFER blanket module assembly using non-destructive neutron diffraction techniques

    Hughes, D.J., E-mail: d.hughes@warwick.ac.uk [WMG, University of Warwick, Coventry CV4 7AL (United Kingdom); Koukovini-Platia, E. [CERN, CH-1211 Geneva 23 (Switzerland); Heeley, E.L. [Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

    2014-02-15

    Highlights: • Residual stresses were determined in a welded EUROFER blanket assembly with integrated cooling channels. • Good agreement was seen between experimentally determined and predicted stresses. • We show that microstructure changes that occur in EUROFER steels during welding must be considered for residual stress determination. • An experimental route is proposed for validation of predicted stresses in reactor components using non-destructive diffraction techniques. - Abstract: Whilst the structural integrity and lifetime considerations in welded joints for blanket modules can be predicted using finite element software, it is essential to prove the validity of these simulations. This paper provides detailed analysis for the first time, of the residual stress state in a laser-welded sample with integral cooling channels. State-of-the-art non-destructive neutron diffraction was employed to determine the triaxial stress state and to understand microstructural changes around the heat affected zone. Synchrotron X-ray diffraction was used to probe the variation of strain-free lattice reference parameter around the weld zone allowing correction of the neutron measurements. This paper details an important experimental route to validation of predicted stresses in complex safety-critical reactor components for future applications.

  20. Breathing adapted radiotherapy for breast cancer: Comparison of free breathing gating with the breath-hold technique

    Background and purpose: Adjuvant radiotherapy after breast-conserving surgery for breast cancer implies a risk of late cardiac and pulmonary toxicity. This is the first study to evaluate cardiopulmonary dose sparing of breathing adapted radiotherapy (BART) using free breathing gating, and to compare this respiratory technique with voluntary breath-hold. Patients and methods: 17 patients were CT-scanned during non-coached breathing manoeuvre including free breathing (FB), end-inspiration gating (IG), end-expiration gating (EG), deep inspiration breath-hold (DIBH) and end-expiration breath-hold (EBH). The Varian Real-time Position Management system (RPMTM) was used to monitor respiratory movement and to gate the scanner. For each breathing phase, a population based internal margin (IM) was estimated based on average chest wall excursion, and incorporated into an individually optimised three-field mono-isocentric wide tangential photon field treatment plan for each scan. The target included the remaining breast, internal mammary nodes and periclavicular nodes. Results: The mean anteroposterior chest wall excursion during FB was 2.5 mm. For IG and EG, the mean excursions within gating windows were 1.1 and 0.7 mm, respectively, whereas for DIBH and EBH the excursions were 4.1 and 2.6 mm, respectively. For patients with left-sided cancer, the median heart volume receiving more than 50% of the prescription dose was reduced from 19.2% for FB to 2.8% for IG and 1.9% for DIBH, and the median left anterior descending (LAD) coronary artery volume was reduced from 88.9% to 22.4% for IG and 3.6% for DIBH. Simultaneously, the median ipsilateral relative lung volume irradiated to >50% of the prescribed target dose for both right- and left-sided cancers was reduced from 45.6% for FB to 29.5% for IG and 27.7% for DIBH. For EBH and EG, both the irradiated heart, LAD and lung volumes increased compared to FB. Conclusions: This is the first study to demonstrate the dosimetric benefits

  1. Dosimetric and geometric evaluation of the use of deformable image registration in adaptive intensity-modulated radiotherapy for head-and-neck cancer

    Eiland, R B; Maare, Christian; Sjöström, D;

    2014-01-01

    The aim of this study was to carry out geometric and dosimetric evaluation of the usefulness of a deformable image registration algorithm utilized for adaptive head-and-neck intensity-modulated radiotherapy. Data consisted of seven patients, each with a planning CT (pCT), a rescanning CT (ReCT) and...... a cone beam CT (CBCT). The CBCT was acquired on the same day (± 1 d) as the ReCT (i.e. at Fraction 17, 18, 23, 24 or 29). The ReCT served as ground truth. A deformed CT (dCT) with structures was created by deforming the pCT to the CBCT. The geometrical comparison was based on the volumes of the...

  2. "NEVER TRUST THE TELLER," HE SAID. "TRUST THE TALE": NARRATIVE TECHNIQUE FROM THE ARABIAN NIGHTS TO POSTMODERN ADAPTATIONS BY RABIH ALAMEDDINE AND PIER PASOLINI

    Saleem, Sobia

    2012-01-01

    AbstractSobia Saleem“Never Trust the Teller,” he said. “Trust the Tale”: Narrative Technique from the Arabian Nights to Postmodern Adaptations by Rabih Alameddine and Pier Pasolini This thesis stems from an examination of Rabih Alameddine's The Hakawati's embedded narrative structure. The roots of this structure reside in the Arabian Night's renowned frame structure, which can be traced to the Islamic aesthetic, primarily its textile culture and organization of the Qur...

  3. The adapted yam minisett technique for producing clean seed yams (Dioscorea Rotundata): Agronomic performance and varietal differences under farmer-managed conditions in Nigeria

    Morse, S; McNamara, N.

    2014-01-01

    White yam (Dioscorea rotundata) is a major root crop grown throughout West Africa but one of the major factors that limits its production is the availability of good quality planting material. This paper described the results of farmer-managed demonstration plots established in 2012 and 2013 designed to promote the Adapted Yam Minisett Technique (AYMT) in Nigeria. The AYMT was developed between 2005 and 2008 to produce quality seed yam tubers at a cost that is viable for small-scale farmers. ...

  4. Volume and dosimetric changes and initial clinical experience of a two-step adaptive intensity modulated radiation therapy (IMRT) scheme for head and neck cancer

    Purpose: The aim of this study was to show the benefit of a two-step intensity modulated radiotherapy (IMRT) method by examining geometric and dosimetric changes. Material and Methods: Twenty patients with pharyngeal cancers treated with two-step IMRT combined with chemotherapy were included. Treatment-planning CT was done twice before IMRT (CT-1) and at the third or fourth week of IMRT for boost IMRT (CT-2). Transferred plans recalculated initial plan on CT-2 were compared with the initial plans on CT-1. Dose parameters were calculated for a total dose of 70 Gy for each plan. Results: The volumes of primary tumors and parotid glands on CT-2 regressed significantly. Parotid glands shifted medially an average of 4.2 mm on CT-2. The mean doses of the parotid glands in the initial and transferred plans were 25.2 Gy and 30.5 Gy, respectively. D2 (dose to 2% of the volume) doses of the spinal cord were 37.1 Gy and 39.2 Gy per 70 Gy, respectively. Of 15 patients in whom xerostomia scores could be evaluated 1–2 years after IMRT, no patient complained of grade 2 or more xerostomia. Conclusions: This two-step IMRT method as an adaptive RT scheme could adapt to changes in body contour, target volumes and risk organs during IMRT

  5. Blood coagulation factor XII drives adaptive immunity during neuroinflammation via CD87-mediated modulation of dendritic cells.

    Göbel, Kerstin; Pankratz, Susann; Asaridou, Chloi-Magdalini; Herrmann, Alexander M; Bittner, Stefan; Merker, Monika; Ruck, Tobias; Glumm, Sarah; Langhauser, Friederike; Kraft, Peter; Krug, Thorsten F; Breuer, Johanna; Herold, Martin; Gross, Catharina C; Beckmann, Denise; Korb-Pap, Adelheid; Schuhmann, Michael K; Kuerten, Stefanie; Mitroulis, Ioannis; Ruppert, Clemens; Nolte, Marc W; Panousis, Con; Klotz, Luisa; Kehrel, Beate; Korn, Thomas; Langer, Harald F; Pap, Thomas; Nieswandt, Bernhard; Wiendl, Heinz; Chavakis, Triantafyllos; Kleinschnitz, Christoph; Meuth, Sven G

    2016-01-01

    Aberrant immune responses represent the underlying cause of central nervous system (CNS) autoimmunity, including multiple sclerosis (MS). Recent evidence implicated the crosstalk between coagulation and immunity in CNS autoimmunity. Here we identify coagulation factor XII (FXII), the initiator of the intrinsic coagulation cascade and the kallikrein-kinin system, as a specific immune cell modulator. High levels of FXII activity are present in the plasma of MS patients during relapse. Deficiency or pharmacologic blockade of FXII renders mice less susceptible to experimental autoimmune encephalomyelitis (a model of MS) and is accompanied by reduced numbers of interleukin-17A-producing T cells. Immune activation by FXII is mediated by dendritic cells in a CD87-dependent manner and involves alterations in intracellular cyclic AMP formation. Our study demonstrates that a member of the plasmatic coagulation cascade is a key mediator of autoimmunity. FXII inhibition may provide a strategy to combat MS and other immune-related disorders. PMID:27188843

  6. High-resolution pulmonary ventilation and perfusion PET/CT allows for functionally adapted intensity modulated radiotherapy in lung cancer

    Background and purpose: To assess the utility of functional lung avoidance using IMRT informed by four-dimensional (4D) ventilation/perfusion (V/Q) PET/CT. Materials and methods: In a prospective clinical trial, patients with non-small cell lung cancer (NSCLC) underwent 4D-V/Q PET/CT scanning before 60 Gy of definitive chemoradiation. Both “highly perfused” (HPLung) and “highly ventilated” (HVLung) lung volumes were delineated using a 70th centile SUV threshold, and a “ventilated lung volume” (VLung) was created using a 50th centile SUV threshold. For each patient four IMRT plans were created, optimised to the anatomical lung, HPLung, HVLung and VLung volumes, respectively. Improvements in functional dose volumetrics when optimising to functional volumes were assessed using mean lung dose (MLD), V5, V10, V20, V30, V40, V50 and V60 parameters. Results: The study cohort consisted of 20 patients with 80 IMRT plans. Plans optimised to HPLung resulted in a significant reduction of functional MLD by a mean of 13.0% (1.7 Gy), p = 0.02. Functional V5, V10 and V20 were improved by 13.2%, 7.3% and 3.8% respectively (p-values < 0.04). There was no significant sparing of dose to functional lung when adapting to VLung or HVLung. Plan quality was highly consistent with a mean PTV D95 and D5 ranging from 60.8 Gy to 61.0 Gy and 63.4 Gy to 64.5 Gy, respectively, and mean conformity and heterogeneity index ranging from 1.11 to 1.17 and 0.94 to 0.95, respectively. Conclusion: IMRT plans adapted to perfused but not ventilated lung on 4D-V/Q PET/CT allowed for reduced dose to functional lung whilst maintaining consistent plan quality

  7. Contribution of the modulation of intensity and the optimization to deliver a dose adapted to the biological heterogeneities

    The recent progress in functional imaging by Positron Emission Tomography (TEP) opens new perspectives in the delineation of target volumes in radiotherapy. The functional data is major; we can intend to adapt the irradiation doses on the tumor activity (TA) and to perform a dose escalation. Our objectives were (i) to characterize the TEP threshold, by quantifying the uncertainties of the target volume contour according to the lesion size and the threshold contour level, (ii) to set up the geometry suited to perform a high-precision irradiation based on the TA, (iii) to estimate the dosimetric impact of this new protocol and (iv) to verify that dosimetry is perfectly distributed. Three original phantoms were specially created to satisfy the constraints met, as well as two virtual phantoms containing 3 dose levels (dose level 3 = TA). Our results showed the importance of the effect threshold-volume on the planning in radiotherapy. To use this irradiation method, the diameter of 1 cm for the third level was able to be reached. A dose escalation of 20 Gy was possible between the second (70 Gy) and the third level (90 Gy). The dosimetric impact estimated on two real cases was suitable - increase of COIN (conformal index) from 0.6 to 0.8 and decrease of NTCP (normal tissue complication probability) of a factor 5 -. In absolute and relative dosimetry, the clinical tolerances were respected. So all the treatment process, going from the diagnosis with the TEP to reveal the TA, to the patient treatment made beforehand on phantom, and going through the ballistic and the dose calculation, was estimated and validated according to our objective to adapt the irradiation to the biological heterogeneities. However such high doses should be carefully estimated before being prescribed clinically and progress is also expected in imaging, because the minimal size which we can irradiate is on the limit of the resolution TEP. (author)

  8. Comparison of conformal and intensity modulated radiation therapy techniques for treatment of pelvic tumors. Analysis of acute toxicity

    This retrospective analysis reports on the comparative outcome of acute gastrointestinal (GI) and genitourinary (GU) toxicities between conformal radiation therapy (CRT) and intensity modulated radiation therapy (IMRT) techniques in the treatment of patients with pelvic tumors. From January 2002 to December 2008, 69 patients with pelvic tumors underwent whole pelvic CRT and 65 underwent whole pelvic IMRT to treat pelvic lymph nodes and primary tumor regions. Total dose to the whole pelvis ranged from 50 to 50.4 Gy in 25 to 28 daily fractions. Chemotherapy (CT) regimen, when employed, was based upon primary tumor. Acute GI and GU toxicities were graded by RTOG/EORTC acute radiation morbidity criteria. Absence of GI symptoms during radiotherapy (grade 0) was more frequently observed in the IMRT group (43.1% versus 8.7; p < 0.001) and medication for diarrhea (Grade 2) was more frequently used in the CRT group (65.2% versus 38.5%; p = 0.002). Acute GI grade 1 and 3 side effects incidence was similar in both groups (18.5% versus 18.8%; p = 0.95 and 0% versus 7.2%; p = 0.058, respectively). Incidence of GU toxicity was similar in both groups (grade 0: 61.5% versus 66.6%, p = 0.54; grade 1: 20% versus 8.7%, p = 0.06; grade 2: 18.5% versus 23.5%, p = 0.50 and grade 3: 0% versus 1.5%, p > 0.99). This comparative case series shows less grade 2 acute GI toxicity in patients treated with whole pelvic IMRT in comparison with those treated with CRT. Incidence of acute GU toxicity was similar in both groups

  9. Simultaneous integrated boost with intensity modulated radiation therapy in brain oligometastases: A feasible technique for developing countries

    Vivek Tiwari

    2015-01-01

    Full Text Available Introduction: To analyze the pattern of brain metastasis (BM, and to use intensity modulated radiation therapy (IMRT for target dose escalation in cases with ≤3 metastatic lesions (oligometastases. Materials and Methods: Thirty-two consecutive cases of BM treated during September 2009 to August 2012 were analyzed retrospectively. Results: The study comprised 13 males (40.62% and 19 females (59.37%. Thirteen (40% patients presented with disseminated intracranial metastases, while 19 (60% had ≤3 foci. In 25 cases (78%, the primary was located either in the breast (14 cases or lung (11 cases. The 13 patients with disseminated intracranial metastases received whole brain radiation therapy to a dose of 30 Gy/10-12 daily fractions (Group A while the 19 cases with ≤3 lesions received an additional dose of 6-10 Gy to gross lesions using a simultaneous integrated boost (SIB with IMRT thus receiving a total dose of 36-40 Gy/12-15 fractions (Group B. Overall survival (OS for the breast primary was 6.3 and lung primary was 5.3 months, respectively. The mean OS for breast cases in Group B was higher (9.5 months as compared to Group A cases (1.9 months and was statistically significant (P = 0.0056. Similarly, primary lung cancer cases in Group B showed a mean OS of 8.75 months versus 2.6 months for Group A cases (P = 0.213. Conclusions: IMRT is a safe and effective technique in cases with oligometastases for dose escalation in the form of SIB.

  10. Intensity Modulated Proton Therapy for Craniospinal Irradiation: Organ-at-Risk Exposure and a Low-Gradient Junctioning Technique

    Stoker, Joshua B., E-mail: stoker.joshua@mayo.edu [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona (United States); Grant, Jonathan [Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Zhu, X. Ronald; Pidikiti, Rajesh [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Mahajan, Anita; Grosshans, David R. [Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

    2014-11-01

    Purpose: To compare field junction robustness and sparing of organs at risk (OARs) during craniospinal irradiation (CSI) using intensity modulated proton therapy (IMPT) to conventional passively scattered proton therapy (PSPT). Methods and Materials: Ten patients, 5 adult and 5 pediatric patients, previously treated with PSPT-based CSI were selected for comparison. Anterior oblique cranial fields, using a superior couch rotation, and posterior spinal fields were used for IMPT planning. To facilitate low-gradient field junctioning along the spine, the inverse-planning IMPT technique was divided into 3 stages. Dose indices describing target coverage and normal tissue dose, in silico error modeling, and film dosimetry were used to assess plan quality. Results: Field junction robustness along the spine was improved using the staged IMPT planning technique, reducing the worst case impact of a 4-mm setup error from 25% in PSPT to <5% of prescription dose. This was verified by film dosimetry for clinical delivery. Exclusive of thyroid dose in adult patients, IMPT plans demonstrated sparing of organs at risk as good or better than PSPT. Coverage of the cribriform plate for pediatric (V95% [percentage of volume of the target receiving at least 95% of the prescribed dose]; 87 ± 11 vs 92 ± 7) and adult (V95%; 94 ± 7 vs 100 ± 1) patients and the clinical target in pediatric (V95%; 98 ± 2 vs 100 ± 1) and adult (V95%; 100 ± 1 vs 100 ± 1) patients for PSPT and IMPT plans, respectively, were comparable or improved. For adult patients, IMPT target dose inhomogeneity was increased, as determined by heterogeneity index (HI) and inhomogeneity coefficient (IC). IMPT lowered maximum spinal cord dose, improved spinal dose homogeneity, and reduced exposure to other OARs. Conclusions: IMPT has the potential to improve CSI plan quality and the homogeneity of intrafractional dose at match lines. The IMPT approach developed may also simplify treatments and reduce

  11. Adapting developing country epidemiological assessment techniques to improve the quality of health needs assessments in developed countries

    Handy Deirdre

    2005-04-01

    Full Text Available Abstract Background We were commissioned to carry out three health assessments in urban areas of Dublin in Ireland. We required an epidemiologically robust method that could collect data rapidly and inexpensively. We were dealing with inadequate health information systems, weak planning data and a history of inadequate recipient involvement in health service planning. These problems had also been identified by researchers carrying out health assessments in developing countries. This paper reports our experience of adapting a cluster survey model originally developed by international organisations to assess community health needs and service coverage in developing countries and applying our adapted model to three urban areas in Dublin, Ireland Methods We adapted the model to control for socio-economic heterogeneity, to take account of the inadequate population list, to ensure a representative sample and to account for a higher prevalence of degenerative and chronic diseases. We employed formal as well as informal communication methods and adjusted data collection times to maximise participation. Results The model we adapted had the capacity to ascertain both health needs and health care delivery needs. The community participated throughout the process and members were trained and employed as data collectors. The assessments have been used by local health boards and non-governmental agencies to plan and deliver better or additional services. Conclusion We were able to carry out high quality health needs assessments in urban areas by adapting and applying a developing country health assessment method. Issues arose relating to health needs assessment as part of the planning cycle and the role of participants in the process.

  12. Stock price forecasting for companies listed on Tehran stock exchange using multivariate adaptive regression splines model and semi-parametric splines technique

    Rounaghi, Mohammad Mahdi; Abbaszadeh, Mohammad Reza; Arashi, Mohammad

    2015-11-01

    One of the most important topics of interest to investors is stock price changes. Investors whose goals are long term are sensitive to stock price and its changes and react to them. In this regard, we used multivariate adaptive regression splines (MARS) model and semi-parametric splines technique for predicting stock price in this study. The MARS model as a nonparametric method is an adaptive method for regression and it fits for problems with high dimensions and several variables. semi-parametric splines technique was used in this study. Smoothing splines is a nonparametric regression method. In this study, we used 40 variables (30 accounting variables and 10 economic variables) for predicting stock price using the MARS model and using semi-parametric splines technique. After investigating the models, we select 4 accounting variables (book value per share, predicted earnings per share, P/E ratio and risk) as influencing variables on predicting stock price using the MARS model. After fitting the semi-parametric splines technique, only 4 accounting variables (dividends, net EPS, EPS Forecast and P/E Ratio) were selected as variables effective in forecasting stock prices.

  13. Volume and dosimetric variations during two-phase adaptive intensity-modulated radiotherapy for locally advanced nasopharyngeal carcinoma.

    Wang, Rui-hao; Zhang, Shu-xu; Zhou, Ling-hong; Zhang, Guo-qian; Yu, Hui; Lin, Xiao-dan; Lin, Shengqu

    2014-01-01

    The aims of this study were to evaluate the volume and dosimetric variations during IMRT for locally advanced NPC and to identify the benefits of a two-phase adaptive IMRT method. Twenty patients with locally advanced NPC having received IMRT treatment were included. Each patient had both an initial planning CT (CT-1) and a repeated CT scan (CT-2) after treatment at a dose of 40 Gy. Three IMRT planning scenarios were compared: (1) the initial plan on the CT-1 (plan-1); (2) the hybrid plan recalculated the initial plan on the CT-2 (plan-2); (3) the replan generated on the CT-2 being used to complete the course of IMRT (plan-3). The mean gross target volume and mean volumes of the positive neck lymph nodes, high-risk clinical target volume, and the left and right parotid glands significantly decreased by 30.2%, 45.1%, 21.1%, 14.7% and 18.2%, respectively on the CT-2. Comparing plan-2 with plan-1, the dose coverage of the targets remained unchanged, whereas the dose delivered to the parotid glands and spinal cord increased significantly. These patients with locally advanced NPC might benefit from replanning because of the sparing of the parotid glands and spinal cord. PMID:24212016

  14. Glucose-Modulated Mitochondria Adaptation in Tumor Cells: A Focus on ATP Synthase and Inhibitor Factor 1

    Irene Mavelli

    2012-02-01

    Full Text Available Warburg’s hypothesis has been challenged by a number of studies showing that oxidative phosphorylation is repressed in some tumors, rather than being inactive per se. Thus, treatments able to shift energy metabolism by activating mitochondrial pathways have been suggested as an intriguing basis for the optimization of antitumor strategies. In this study, HepG2 hepatocarcinoma cells were cultivated with different metabolic substrates under conditions mimicking “positive” (activation/biogenesis or “negative” (silencing mitochondrial adaptation. In addition to the expected up-regulation of mitochondrial biogenesis, glucose deprivation caused an increase in phosphorylating respiration and a rise in the expression levels of the ATP synthase β subunit and Inhibitor Factor 1 (IF1. Hyperglycemia, on the other hand, led to a markedly decreased level of the transcriptional coactivator PGC-α suggesting down-regulation of mitochondrial biogenesis, although no change in mitochondrial mass and no impairment of phosphorylating respiration were observed. Moreover, a reduction in mitochondrial networking and in ATP synthase dimer stability was produced. No effect on β-ATP synthase expression was elicited. Notably, hyperglycemia caused an increase in IF1 expression levels, but it did not alter the amount of IF1 associated with ATP synthase. These results point to a new role of IF1 in relation to high glucose utilization by tumor cells, in addition to its well known effect upon mitochondrial ATP synthase regulation.

  15. Verification of the CENTRM Module for Adaptation of the SCALE Code to NGNP Prismatic and PBR Core Designs

    Ganapol, Barry; Maldonado, Ivan

    2014-01-23

    The generation of multigroup cross sections lies at the heart of the very high temperature reactor (VHTR) core design, whether the prismatic (block) or pebble-bed type. The design process, generally performed in three steps, is quite involved and its execution is crucial to proper reactor physics analyses. The primary purpose of this project is to develop the CENTRM cross-section processing module of the SCALE code package for application to prismatic or pebble-bed core designs. The team will include a detailed outline of the entire processing procedure for application of CENTRM in a final report complete with demonstration. In addition, they will conduct a thorough verification of the CENTRM code, which has yet to be performed. The tasks for this project are to: Thoroughly test the panel algorithm for neutron slowing down; Develop the panel algorithm for multi-materials; Establish a multigroup convergence 1D transport acceleration algorithm in the panel formalism; Verify CENTRM in 1D plane geometry; Create and test the corresponding transport/panel algorithm in spherical and cylindrical geometries; and, Apply the verified CENTRM code to current VHTR core design configurations for an infinite lattice, including assessing effectiveness of Dancoff corrections to simulate TRISO particle heterogeneity.

  16. Verification of the CENTRM Module for Adaptation of the SCALE Code to NGNP Prismatic and PBR Core Designs

    The generation of multigroup cross sections lies at the heart of the very high temperature reactor (VHTR) core design, whether the prismatic (block) or pebble-bed type. The design process, generally performed in three steps, is quite involved and its execution is crucial to proper reactor physics analyses. The primary purpose of this project is to develop the CENTRM cross-section processing module of the SCALE code package for application to prismatic or pebble-bed core designs. The team will include a detailed outline of the entire processing procedure for application of CENTRM in a final report complete with demonstration. In addition, they will conduct a thorough verification of the CENTRM code, which has yet to be performed. The tasks for this project are to: Thoroughly test the panel algorithm for neutron slowing down; Develop the panel algorithm for multi-materials; Establish a multigroup convergence 1D transport acceleration algorithm in the panel formalism; Verify CENTRM in 1D plane geometry; Create and test the corresponding transport/panel algorithm in spherical and cylindrical geometries; and, Apply the verified CENTRM code to current VHTR core design configurations for an infinite lattice, including assessing effectiveness of Dancoff corrections to simulate TRISO particle heterogeneity

  17. Shutter array technique for real-time non-invasive extraction of individual channel responses in multi-channel CPV modules

    Cook, John P. D.; Yandt, Mark D.; Kelly, Michael; Wheeldon, Jeffrey F.; Hinzer, Karin; Schriemer, Henry

    2013-10-01

    Concentrator photovoltaic (CPV) solar energy systems use optics to concentrate direct normal incidence (DNI) sunlight onto multi-junction photovoltaic (MJPV) cells fabricated from III-V compound semiconductors on germanium substrates. The MJPV receiver, which integrates cell and bypass diode, is then mated with its concentrating optic to form a channel, and several such channels form a CPV module, in which the receivers are connected electrically in series. The two ends of the module receiver string are brought out to a single pair of electrical connections, at which point the lightcurrent- voltage (L-I-V) response of the entire module can be tested. With commercial CPV modules commonly sealed against outdoor exposure, there are no other accessible test points, and field installation on trackers further complicates access to performance data. There are many physical phenomena influencing module performance, and in early development and commercialization some of these may not yet be completely under control. Unambiguous diagnosis of such phenomena from one full-module L-I-V curve is problematic. Simple, fast test methods are needed to develop more detailed information from full-module on-tracker testing, without opening up modules in the field. We describe a test protocol, using a simple optical shutter array constructed to fit mechanically over the module. When module L-I-V curves are recorded for each of various combinations of open and closed shutters, the information can be used to identify one or more anomalous channels, and to further identify the kind of anomaly present, such as optical misalignment, conductor failure, series or shunt resistance, and so on. Simulated results from anomaly models can be compared with the measured results to identify the anomalous behaviour. Results herein are compared with direct single-channel measurements to verify the technique. The L-I-V response curves were obtained in continuous real time, an approach found to be more

  18. Intensity-modulated radiation therapy for pancreatic and prostate cancer using pulsed low–dose rate delivery techniques

    Li, Jie; Lang, Jinyi; Wang, Pei; Kang, Shengwei [Department of Radiation Oncology, Sichuan Cancer Hospital, Chengdu (China); Lin, Mu-han; Chen, Xiaoming [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Chen, Fu; Guo, Ming [Department of Radiation Oncology, Eye Ear Nose and Throat Hospital of Fudan University, Shanghai (China); Chen, Lili [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Ma, Chang-Ming Charlie, E-mail: charlie.ma@fccc.edu [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States)

    2014-01-01

    Reirradiation of patients who were previously treated with radiotherapy is vastly challenging. Pulsed low–dose rate (PLDR) external beam radiotherapy has the potential to reduce normal tissue toxicities while providing significant tumor control for recurrent cancers. This work investigates treatment planning techniques for intensity-modulated radiation therapy (IMRT)-based PLDR treatment of various sites, including cases with pancreatic and prostate cancer. A total of 20 patients with clinical recurrence were selected for this study, including 10 cases with pancreatic cancer and 10 with prostate cancer. Large variations in the target volume were included to test the ability of IMRT using the existing treatment planning system and optimization algorithm to deliver uniform doses in individual gantry angles/fields for PLDR treatments. Treatment plans were generated with 10 gantry angles using the step-and-shoot IMRT delivery technique, which can be delivered in 3-minute intervals to achieve an effective low dose rate of 6.7 cGy/min. Instead of dose constraints on critical structures, ring structures were mainly used in PLDR-IMRT optimization. In this study, the PLDR-IMRT plans were compared with the PLDR-3-dimensional conformal radiation therapy (3DCRT) plans and the PLDR-RapidArc plans. For the 10 cases with pancreatic cancer that were investigated, the mean planning target volume (PTV) dose for each gantry angle in the PLDR-IMRT plans ranged from 17.6 to 22.4 cGy. The maximum doses ranged between 22.9 and 34.8 cGy. The minimum doses ranged from 8.2 to 17.5 cGy. For the 10 cases with prostate cancer that were investigated, the mean PTV doses for individual gantry angles ranged from 18.8 to 22.6 cGy. The maximum doses per gantry angle were between 24.0 and 34.7 cGy. The minimum doses per gantry angle ranged from 4.4 to 17.4 cGy. A significant reduction in the organ at risk (OAR) dose was observed with the PLDR-IMRT plan when compared with that using the PLDR-3DCRT

  19. Intensity-modulated radiation therapy for pancreatic and prostate cancer using pulsed low–dose rate delivery techniques

    Reirradiation of patients who were previously treated with radiotherapy is vastly challenging. Pulsed low–dose rate (PLDR) external beam radiotherapy has the potential to reduce normal tissue toxicities while providing significant tumor control for recurrent cancers. This work investigates treatment planning techniques for intensity-modulated radiation therapy (IMRT)-based PLDR treatment of various sites, including cases with pancreatic and prostate cancer. A total of 20 patients with clinical recurrence were selected for this study, including 10 cases with pancreatic cancer and 10 with prostate cancer. Large variations in the target volume were included to test the ability of IMRT using the existing treatment planning system and optimization algorithm to deliver uniform doses in individual gantry angles/fields for PLDR treatments. Treatment plans were generated with 10 gantry angles using the step-and-shoot IMRT delivery technique, which can be delivered in 3-minute intervals to achieve an effective low dose rate of 6.7 cGy/min. Instead of dose constraints on critical structures, ring structures were mainly used in PLDR-IMRT optimization. In this study, the PLDR-IMRT plans were compared with the PLDR-3-dimensional conformal radiation therapy (3DCRT) plans and the PLDR-RapidArc plans. For the 10 cases with pancreatic cancer that were investigated, the mean planning target volume (PTV) dose for each gantry angle in the PLDR-IMRT plans ranged from 17.6 to 22.4 cGy. The maximum doses ranged between 22.9 and 34.8 cGy. The minimum doses ranged from 8.2 to 17.5 cGy. For the 10 cases with prostate cancer that were investigated, the mean PTV doses for individual gantry angles ranged from 18.8 to 22.6 cGy. The maximum doses per gantry angle were between 24.0 and 34.7 cGy. The minimum doses per gantry angle ranged from 4.4 to 17.4 cGy. A significant reduction in the organ at risk (OAR) dose was observed with the PLDR-IMRT plan when compared with that using the PLDR-3DCRT

  20. Review of small-angle coronagraphic techniques in the wake of ground-based second-generation adaptive optics systems

    Mawet, Dimitri; Lawson, Peter; Mugnier, Laurent; Traub, Wesley; Boccaletti, Anthony; Trauger, John; Gladysz, Szymon; Serabyn, Eugene; Milli, Julien; Belikov, Ruslan; Kasper, Markus; Baudoz, Pierre; Macintosh, Bruce; Marois, Christian; Oppenheimer, Ben; Barrett, Harrisson; Beuzit, Jean-Luc; Devaney, Nicolas; Girard, Julien; Guyon, Olivier; Krist, John; Mennesson, Bertrand; Mouillet, David; Murakami, Naoshi; Poyneer, Lisa; Savransky, Dmitri; ́erinaud, Christophe V; Wallace, James K

    2012-01-01

    Small-angle coronagraphy is technically and scientifically appealing because it enables the use of smaller telescopes, allows covering wider wavelength ranges, and potentially increases the yield and completeness of circumstellar environment - exoplanets and disks - detection and characterization campaigns. However, opening up this new parameter space is challenging. Here we will review the four posts of high contrast imaging and their intricate interactions at very small angles (within the first 4 resolution elements from the star). The four posts are: choice of coronagraph, optimized wavefront control, observing strategy, and post-processing methods. After detailing each of the four foundations, we will present the lessons learned from the 10+ years of operations of zeroth and first-generation adaptive optics systems. We will then tentatively show how informative the current integration of second-generation adaptive optics system is, and which lessons can already be drawn from this fresh experience. Then, w...

  1. A Comparative Study between Moravec and Harris Corner Detection of Noisy Images Using Adaptive Wavelet Thresholding Technique

    Dey, Nilanjan; Nandi, Pradipti; Barman, Nilanjana; Das, Debolina; Chakraborty, Subhabrata

    2012-01-01

    In this paper a comparative study between Moravec and Harris Corner Detection has been done for obtaining features required to track and recognize objects within a noisy image. Corner detection of noisy images is a challenging task in image processing. Natural images often get corrupted by noise during acquisition and transmission. As Corner detection of these noisy images does not provide desired results, hence de-noising is required. Adaptive wavelet thresholding approach is applied for the...

  2. Feature-Based Adaptive Tolerance Tree (FATT): An Efficient Indexing Technique for Content-Based Image Retrieval Using Wavelet Transform

    AnandhaKumar, Dr. P.; V. Balamurugan

    2010-01-01

    This paper introduces a novel indexing and access method, called Feature- Based Adaptive Tolerance Tree (FATT), using wavelet transform is proposed to organize large image data sets efficiently and to support popular image access mechanisms like Content Based Image Retrieval (CBIR).Conventional database systems are designed for managing textual and numerical data and retrieving such data is often based on simple comparisons of text or numerical values. However, this method is no longer adequa...

  3. Risk-adapted partial larynx and/or carotid artery sparing modulated radiation therapy of glottic cancer

    To evaluate outcome in patients with glottic cancer treated with intensity-modulated radiotherapy (IMRT) and to show effectiveness of partial laryngeal- and/or carotid artery sparing in low to intermediate risk tumors. Retrospective analysis. From 01/2004 to 03/2013 77 consecutive patients presenting with glottic cancer were treated in our department with IMRT as definitive treatment. T-stages distributed as follows: T1: n = 17, T2: n = 24, T3: n = 15, T4: n = 13 and recurrences: 8 patients. Concomitant systemic therapy was applied in 39 patients consisting of either cisplatin or cetuximab. Mean/median follow-up (FU) time was 32.2/28 months (range: 4–98.7). Three year local control (LC), ultimate LRC and laryngectomy free survival rate was 77%, 92% and 80%, respectively. Three year overall survival of the entire cohort was 81%. Three year local control for T1/T2, T3/T4, and recurred tumors was 95%, 65%, and 38%, respectively. Three year overall survival was 86% for T1-4 stages, 55% for recurred disease, respectively. Partial laryngeal/carotid artery sparing was performed in all T1 patients (n = 17) and 17/22 T2N0 patients. Rate of late sequels was low. IMRT for glottic cancer shows high control rates. In low to intermediate risk tumors an individualized treatment volume with partial larynx +/- carotid artery sparing is effective and holds the potential to reduce long term toxicity. The therapeutic outcome was not compromised

  4. Study and Analysis of Three Phase Voltage Source Inverter Fed Induction Motor Drive in Various Pulse Width Modulation Techniques

    S. Manivannan, S. Veerakuma; P. Karuppusamy, A. Nandhakumar

    2014-01-01

    The Three Phase Voltage Source Inverter supplies invariably required variable voltage and frequency of the adjustable speed drive system. A number of pulse width modulation (PWM) schemes are used to obtain variable voltage and frequency supply from an inverter. The most widely used PWM scheme for a Three Phase Voltage Source Inverter is carrier based sinusoidal PWM and Space Vector Pulse Width Modulation (SVPWM). There is an increasing trend of using SVPWM, beca...

  5. Decision feedback Channel Estimation - A Precursor for Adaptive Data Transmission Management

    Li, M; Bateman, A.; McGeehan, JP

    1991-01-01

    Two concepts are introduced: first, the notion of adaptive data transmission management to optimize modulation format and coding to channel conditions and, second, as a consequence of this strategy, the proposal of a reverse modulation channel sounding technique for elimination of the irreducible error rate floor, which otherwise limits modem performance under good signal conditions. The adaptive data transmission concept can potentially increase transmission throughput on a practical data ne...

  6. Intensity modulated arc therapy implementation in a three phase adaptive 18F-FDG-PET voxel intensity-based planning strategy for head-and-neck cancer

    This study investigates the implementation of a new intensity modulated arc therapy (IMAT) class solution in comparison to a 6-static beam step-and-shoot intensity modulated radiotherapy (s-IMRT) for three-phase adaptive 18F-FDG-PET-voxel-based dose-painting-by-numbers (DPBN) for head-and-neck cancer. We developed 18F-FDG-PET-voxel intensity-based IMAT employing multiple arcs and compared it to clinically used s-IMRT DPBN. Three IMAT plans using 18F-FDG-PET/CT acquired before treatment (phase I), after 8 fractions (phase II) and CT acquired after 18 fractions (phase III) were generated for each of 10 patients treated with 3 s-IMRT plans based on the same image sets. Based on deformable image registration (ABAS, version 0.41, Elekta CMS Software, Maryland Heights, MO), doses of the 3 plans were summed on the pretreatment CT using validated in-house developed software. Dosimetric indices in targets and organs-at-risk (OARs), biologic conformity of treatment plans set at ≤5 %, treatment quality and efficiency were compared between IMAT and s-IMRT for the whole group and for individual patients. Doses to most organs-at-risk (OARs) were significantly better in IMAT plans, while target levels were similar for both types of plans. On average, IMAT ipsilateral and contralateral parotid mean doses were 14.0 % (p = 0.001) and 12.7 % (p < 0.001) lower, respectively. Pharyngeal constrictors D50% levels were similar or reduced with up to 54.9 % for IMAT compared to s-IMRT for individual patient cases. IMAT significantly improved biologic conformity by 2.1 % for treatment phases I and II. 3D phantom measurements reported an agreement of ≥95 % for 3 % and 3 mm criteria for both treatment modalities. IMAT delivery time was significantly shortened on average by 41.1 %. IMAT implementation significantly improved the biologic conformity as compared to s-IMRT in adaptive dose-escalated DPBN treatments. The better OAR sparing and faster delivery highly improved the treatment

  7. Adaptive Radiation for Lung Cancer

    Daniel R. Gomez

    2011-01-01

    need to spare surrounding critical structures. Evolving radiotherapy technologies, such as four-dimensional (4D image-based motion management, daily on-board imaging and adaptive radiotherapy based on volumetric images over the course of radiotherapy, have enabled us to deliver higher dose to target while minimizing normal tissue toxicities. The image-guided radiotherapy adapted to changes of motion and anatomy has made the radiotherapy more precise and allowed ablative dose delivered to the target using novel treatment approaches such as intensity-modulated radiation therapy, stereotactic body radiation therapy, and proton therapy in lung cancer, techniques used to be considered very sensitive to motion change. Future clinical trials using real time tracking and biological adaptive radiotherapy based on functional images are proposed.

  8. Bioinspired, roughness-induced, water and oil super-philic and super-phobic coatings prepared by adaptable layer-by-layer technique

    Philip S. Brown; Bharat Bhushan

    2015-01-01

    Coatings with specific surface wetting properties are of interest for anti-fouling, anti-fogging, anti-icing, self-cleaning, anti-smudge, and oil-water separation applications. Many previous bioinspired surfaces are of limited use due to a lack of mechanical durability. Here, a layer-by-layer technique is utilized to create coatings with four combinations of water and oil repellency and affinity. An adapted layer-by-layer approach is tailored to yield specific surface properties, resulting in...

  9. Assessment of adaptability of zebu cattle ( Bos indicus) breeds in two different climatic conditions: using cytogenetic techniques on genome integrity

    Kumar, Anil; Waiz, Syma Ashraf; Sridhar Goud, T.; Tonk, R. K.; Grewal, Anita; Singh, S. V.; Yadav, B. R.; Upadhyay, R. C.

    2016-06-01

    The aim of this study was to evaluate the genome integrity so as to assess the adaptability of three breeds of indigenous cattle reared under arid and semi-arid regions of Rajasthan (Bikaner) and Haryana (Karnal) India. The cattle were of homogenous group (same age and sex) of indigenous breeds viz. Sahiwal, Tharparkar and Kankrej. A total of 100 animals were selected for this study from both climatic conditions. The sister chromatid exchanges (SCE's), chromosomal gaps and chromatid breaks were observed in metaphase plates of chromosome preparations obtained from in vitro culture of peripheral blood lymphocytes. The mean number of breaks and gaps in Sahiwal and Tharparkar of semi-arid zone were 8.56 ± 3.16, 6.4 ± 3.39 and 8.72 ± 2.04, 3.52 ± 6.29, respectively. Similarly, the mean number of breaks and gaps in Tharparkar and Kankrej cattle of arid zone were 5.26 ± 1.76, 2.74 ± 1.76 and 5.24 ± 1.84, 2.5 ± 1.26, respectively. The frequency of SCEs in chromosomes was found significantly higher ( P 0.05) was observed in the same zone. The analysis of frequency of CAs and SCEs revealed significant effects of environmental conditions on the genome integrity of animals, thereby indicating an association with their adaptability.

  10. Laser Patterning Pretreatment before Thermal Spraying: A Technique to Adapt and Control the Surface Topography to Thermomechanical Loading and Materials

    Kromer, Robin; Costil, Sophie; Cormier, Jonathan; Berthe, Laurent; Peyre, Patrice; Courapied, Damien

    2016-02-01

    Coating characteristics are highly dependent on substrate preparation and spray parameters. Hence, the surface must be adapted mechanically and physicochemically to favor coating-substrate adhesion. Conventional surface preparation methods such as grit blasting are limited by surface embrittlement and produce large plastic deformations throughout the surface, resulting in compressive stress and potential cracks. Among all such methods, laser patterning is suitable to prepare the surface of sensitive materials. No embedded grit particles can be observed, and high-quality coatings are obtained. Finally, laser surface patterning adapts the impacted surface, creating large anchoring area. Optimized surface topographies can then be elaborated according to the material as well as the application. The objective of this study is to compare the adhesive bond strength between two surface preparation methods, namely grit blasting and laser surface patterning, for two material couples used in aerospace applications: 2017 aluminum alloy and AISI 304L stainless steel coated with NiAl and YSZ, respectively. Laser patterning significantly increases adherence values for similar contact area due to mixed-mode (cohesive and adhesive) failure. The coating is locked in the pattern.

  11. One-step synthesis of hybrid inorganic-organic nanocomposite coatings by novel laser adaptive ablation deposition technique

    Serbezov, Valery; Sotirov, Sotir

    2013-03-01

    A novel approach for one-step synthesis of hybrid inorganic-organic nanocomposite coatings by new modification of Pulsed Laser Deposition technology called Laser Adaptive Ablation Deposition (LAAD) is presented. Hybrid nanocomposite coatings including Mg- Rapamycin and Mg- Desoximetasone were produced by UV TEA N2 laser under low vacuum (0.1 Pa) and room temperature onto substrates from SS 316L, KCl and NaCl. The laser fluence for Mg alloy was 1, 8 J/cm2 and for Desoximetasone 0,176 J/cm2 and for Rapamycin 0,118 J/cm2 were respectively. The threedimensional two-segmented single target was used to adapt the interaction of focused laser beam with inorganic and organic material. Magnesium alloy nanoparticles with sizes from 50 nm to 250 nm were obtained in organic matrices. The morphology of nanocomposites films were studied by Bright field / Fluorescence optical microscope and Scanning Electron Microscope (SEM). Fourier Transform Infrared (FTIR) spectroscopy measurements were applied in order to study the functional properties of organic component before and after the LAAD process. Energy Dispersive X-ray Spectroscopy (EDX) was used for identification of Mg alloy presence in hybrid nanocomposites coatings. The precise control of process parameters and particularly of the laser fluence adjustment enables transfer on materials with different physical chemical properties and one-step synthesis of complex inorganic- organic nanocomposites coatings.

  12. Assessment of adaptability of zebu cattle ( Bos indicus) breeds in two different climatic conditions: using cytogenetic techniques on genome integrity

    Kumar, Anil; Waiz, Syma Ashraf; Sridhar Goud, T.; Tonk, R. K.; Grewal, Anita; Singh, S. V.; Yadav, B. R.; Upadhyay, R. C.

    2016-06-01

    The aim of this study was to evaluate the genome integrity so as to assess the adaptability of three breeds of indigenous cattle reared under arid and semi-arid regions of Rajasthan (Bikaner) and Haryana (Karnal) India. The cattle were of homogenous group (same age and sex) of indigenous breeds viz. Sahiwal, Tharparkar and Kankrej. A total of 100 animals were selected for this study from both climatic conditions. The sister chromatid exchanges (SCE's), chromosomal gaps and chromatid breaks were observed in metaphase plates of chromosome preparations obtained from in vitro culture of peripheral blood lymphocytes. The mean number of breaks and gaps in Sahiwal and Tharparkar of semi-arid zone were 8.56 ± 3.16, 6.4 ± 3.39 and 8.72 ± 2.04, 3.52 ± 6.29, respectively. Similarly, the mean number of breaks and gaps in Tharparkar and Kankrej cattle of arid zone were 5.26 ± 1.76, 2.74 ± 1.76 and 5.24 ± 1.84, 2.5 ± 1.26, respectively. The frequency of SCEs in chromosomes was found significantly higher ( P differences ( P different zones, i.e. arid and semi-arid, whereas no significant difference ( P > 0.05) was observed in the same zone. The analysis of frequency of CAs and SCEs revealed significant effects of environmental conditions on the genome integrity of animals, thereby indicating an association with their adaptability.

  13. An innovative technique for contrast enhancement of computed tomography images using normalized gamma-corrected contrast-limited adaptive histogram equalization

    Al-Ameen, Zohair; Sulong, Ghazali; Rehman, Amjad; Al-Dhelaan, Abdullah; Saba, Tanzila; Al-Rodhaan, Mznah

    2015-12-01

    Image contrast is an essential visual feature that determines whether an image is of good quality. In computed tomography (CT), captured images tend to be low contrast, which is a prevalent artifact that reduces the image quality and hampers the process of extracting its useful information. A common tactic to process such artifact is by using histogram-based techniques. However, although these techniques may improve the contrast for different grayscale imaging applications, the results are mostly unacceptable for CT images due to the presentation of various faults, noise amplification, excess brightness, and imperfect contrast. Therefore, an ameliorated version of the contrast-limited adaptive histogram equalization (CLAHE) is introduced in this article to provide a good brightness with decent contrast for CT images. The novel modification to the aforesaid technique is done by adding an initial phase of a normalized gamma correction function that helps in adjusting the gamma of the processed image to avoid the common errors of the basic CLAHE of the excess brightness and imperfect contrast it produces. The newly developed technique is tested with synthetic and real-degraded low-contrast CT images, in which it highly contributed in producing better quality results. Moreover, a low intricacy technique for contrast enhancement is proposed, and its performance is also exhibited against various versions of histogram-based enhancement technique using three advanced image quality assessment metrics of Universal Image Quality Index (UIQI), Structural Similarity Index (SSIM), and Feature Similarity Index (FSIM). Finally, the proposed technique provided acceptable results with no visible artifacts and outperformed all the comparable techniques.

  14. Model-based iterative reconstruction technique for radiation dose reduction in chest CT: comparison with the adaptive statistical iterative reconstruction technique

    To prospectively evaluate dose reduction and image quality characteristics of chest CT reconstructed with model-based iterative reconstruction (MBIR) compared with adaptive statistical iterative reconstruction (ASIR). One hundred patients underwent reference-dose and low-dose unenhanced chest CT with 64-row multidetector CT. Images were reconstructed with 50 % ASIR-filtered back projection blending (ASIR50) for reference-dose CT, and with ASIR50 and MBIR for low-dose CT. Two radiologists assessed the images in a blinded manner for subjective image noise, artefacts and diagnostic acceptability. Objective image noise was measured in the lung parenchyma. Data were analysed using the sign test and pair-wise Student's t-test. Compared with reference-dose CT, there was a 79.0 % decrease in dose-length product with low-dose CT. Low-dose MBIR images had significantly lower objective image noise (16.93 ± 3.00) than low-dose ASIR (49.24 ± 9.11, P < 0.01) and reference-dose ASIR images (24.93 ± 4.65, P < 0.01). Low-dose MBIR images were all diagnostically acceptable. Unique features of low-dose MBIR images included motion artefacts and pixellated blotchy appearances, which did not adversely affect diagnostic acceptability. Diagnostically acceptable chest CT images acquired with nearly 80 % less radiation can be obtained using MBIR. MBIR shows greater potential than ASIR for providing diagnostically acceptable low-dose CT images without severely compromising image quality. (orig.)

  15. Adaptive segmentation of digital mammograms through reinforcement learning

    LIU Xin-yue; FANG Xiao-xuan; HUANG Lian-qing

    2005-01-01

    An approach based on reinfocement learning for the automated segmentation is presented. The approach consists of two modules:segmentation module and learning module. The segmentation module uses the region-growing algorithm combined with the smooth filtering and the morphological filtering to segment mammograms. The learning module uses the segmentation output as the feedback to learn to select the optimal parameter settings of the segmentation algorithm according to the image properties using reinforcement learning techniques. The approach can adapt itself to various kinds of mammograms through training and therefore obviates the tedious and error-prone tuning of parameter settings manually. Quantitative test results show that the approach is accurate for several kinds of mammograms. Compared to previously proposed approaches,the approach is more adaptable to different mammograms.

  16. Design of the Electronic Brake Pressure Modulator Using a Direct Adaptive Fuzzy Controller in Commercial Vehicles for the Safety of Braking in Fail

    Kim, Hunmo

    In the brake systems, it is important to reduce the rear brake pressure in order to secure the safety of the vehicle in braking. So, there was some research that reduced and controlled the rear brake pressure exactly like a L. S. P. V and a E. L. S. P. V. However, the previous research has some weaknesses: the L. S. P. V is a mechanical system and its brake efficiency is lower than the efficiency of E. L. S. P. V. But, the cost of E. L. S. P. V is very higher so its application to the vehicle is very difficult. Additionally, when a fail appears in the circuit which controls the valves, the fail results in some wrong operation of the valves. But, the previous researchers didn't take the effect of fail into account. Hence, the efficiency of them is low and the safety of the vehicle is not confirmed. So, in this paper we develop a new economical pressure modulator that exactly controls brake pressure and confirms the safety of the vehicle in any case using a direct adaptive fuzzy controller.

  17. FEASIBILITY FOR USING HYPOFRACTIONATED STEREOTACTIC VOLUMETRIC MODULATED ARC RADIOTHERAPY (VMAT) WITH ADAPTIVE PLANNING FOR TREATMENT OF THYMOMA IN RABBITS: 15 CASES.

    Dolera, Mario; Malfassi, Luca; Mazza, Giovanni; Urso, Gaetano; Sala, Massimo; Marcarini, Silvia; Carrara, Nancy; Pavesi, Simone; Finesso, Sara; Kent, Michael S

    2016-05-01

    Thymoma is a relatively common tumor in rabbits. Treatment with surgery, radiation therapy, and chemotherapy alone or in combination has been reported with varying outcomes. Stereotactic volumetric modulated arc radiotherapy delivered in a hypofractionated manner allows high doses of radiation to be delivered to the target volume while allowing sparing of adjacent critical structures. This therapy is ideally suited for thymomas in rabbits given their size, the difficulty of multiple anesthesia episodes and the complexity of the radiotherapy plans required due to the tumor's proximity to the heart, lungs, and mediastinal structures. Fifteen rabbits with thymoma were prospectively recruited for this observational, single institution, single arm clinical study. All rabbits were imaged with both computed tomography (CT) and magnetic resonance imaging (MRI). A total dose of 40 Gy in six fractions was delivered using a single arc over an 11-day period with repeat CT simulation done every other fraction for adaptive planning. Follow-up evaluation was done through repeat CT and MRI imaging and revealed complete responses using the Response Evaluation Criteria in Solid Tumors (RECIST) criteria. Two rabbits had died at 618 and 718 days, 10 were alive and three were lost to follow-up. Observed acute and late effects were graded according to the Veterinary Radiation Therapy Oncology Group (VRTOG) criteria and were found to be minimal. PMID:26748539

  18. Nonlinearity and Phase Noise Tolerant 75-110 GHz Signal over Fiber System Using Phase Modulation Technique

    Deng, Lei; Pang, Xiaodan; Zhang, Xu; Yu, Xianbin; Liu, Deming; Tafur Monroy, Idelfonso

    2013-01-01

    We report on the transmission of 8 Gb/s 0 dB PAPR 16QAM-OFDM W-band (75-110 GHz) signals over 22.8km SMF without phase noise compensation by using a phase modulator in the optical heterodyne up-convertor.......We report on the transmission of 8 Gb/s 0 dB PAPR 16QAM-OFDM W-band (75-110 GHz) signals over 22.8km SMF without phase noise compensation by using a phase modulator in the optical heterodyne up-convertor....

  19. Ultra-Stable Rubidium-Stabilized External-Cavity Diode Laser Based on the Modulation Transfer Spectroscopy Technique

    QI Xiang-Hui; CHEN Wen-Lan; YI Lin; ZHOU Da-Wei; ZHOU Tong; XIAO Qin; DUAN Jun; ZHOU Xiao-Ji; CHEN Xu-Zong

    2009-01-01

    @@ We construct an ultra-stable external-cavity diode laser via modulation transfer spectroscopy referencing on a hyperfine component of the 87Rb D2 lines at 780 hm. The Doppler-free dispersion-like modulation transfer signal is obtained with high signal-to-noise-ratio. The instability of the laser frequency is measured by beating with an optical frequency comb which is phase-locked to an ultra-stable oven controlled crystal oscillator. The Allan deviation is 3.9×10-13 at 1s averaging time and 9.8×10-14 at 90s averaging time.

  20. Sepsis as a modulator of adaptation to low and high carbohydrate and low and high fat intakes.

    Wolfe, R R

    1999-04-01

    Catabolism of lean body mass (particularly muscle) occurs in sepsis and other forms of critical illness despite apparently adequate nutritional support. The determination of the optimal balance of carbohydrate and fat intake in this circumstance should be based on the resulting effect on the maintenance of lean body mass, and the nature and extent of any side effects. The general stress response involves a disruption in normal glucoregulation, in that hepatic glucose production is accelerated and the normal blood glucose lowering action of insulin is diminished. Nonetheless, the capacity to oxidize glucose once inside the cells is not impaired. Lipolysis, or the breakdown of peripheral triglycerides to free fatty acids (FFA) and glycerol, is accelerated in critical illness, to a greater extent than fat oxidation. Provision of exogenous fat maintains fat stores, but has minimal effect on the direct oxidation of plasma FFA. From the results of oxidation studies, it seems that about 5 mg kg x min of glucose can be readily oxidized, and the balance of energy will be supplied by the oxidation of fat, either endogenous or exogenous. However, an additional consideration in determining the optimal caloric substrate is that insulin is a potent anabolic hormone and stimulates muscle protein synthesis. Consequently, provision of exogenous insulin enhances retention of muscle. This procedure dictates that almost all non-protein calories be provided as carbohydrate to avoid hypoglycemia. Preliminary studies suggest this may be the optimal approach in critically ill patients. Glucose and fatty acids are the major energy substrates in the body. The oxidative metabolism of these substrates provides the ATP needed for physiological function, including protein synthesis. Over the past 20 y, development of new techniques in nutritional support have made it possible to provide large amounts of carbohydrate and fat to critically-ill patients, along with protein or amino acids. However