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Sample records for adaptive modulation techniques

  1. A Design Technique for Adapting Number and Boundaries of Reconfigurable Modules at Runtime

    Directory of Open Access Journals (Sweden)

    Thilo Pionteck

    2009-01-01

    Full Text Available Runtime reconfigurable system-on-chip designs for FPGAs pose manifold demands on the underlying system architecture and design tool capabilities. The system architecture has to support varying communication needs of a changing number of processing units mapped onto diverse locations. Design tools should support an arbitrary placement of processing modules and the adjustment of boundaries of reconfigurable regions to the size of the actually instantiated processing modules. While few works address the design of flexible system architectures, the adjustment of boundaries of reconfigurable regions to the size of the actually instantiated processing modules is hardly ever considered due to design tool limitations. In this paper, a technique for circumventing this restriction is presented. It allows for a rededication of the reconfigurable area to a different number of individually sized reconfigurable regions. This technique is embedded in the design flow of a runtime reconfigurable system architecture for Xilinx Virtex-4 FPGAs. The system architecture will also be presented to provide a realistic application example.

  2. Adaptive Modulation and Coding for LTE Wireless Communication

    Science.gov (United States)

    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.

  3. Modulation Techniques for Li-Fi

    OpenAIRE

    Islim, Mohamed; Haas, Harald

    2016-01-01

    Abstract:Modulation techniques for light fidelity (Li-Fi) are reviewed in this paper. Li-Fi is the fully networked solution for multiple users that combines communication and illumination simultaneously. Light emitting diodes (LEDs) are used in Li-Fi as visible light transmitters, therefore, only intensity modulated direct detected modulation techniques can be achieved. Single carrier modulation techniques are straightforward to be used in Li-Fi, however, computationally complex equalization ...

  4. Research on Adaptive Delta Modulators

    Science.gov (United States)

    1979-10-01

    practical, and instead, other techni- ques are employed such as Transform Coding, Delta PCM ( DPCM ) or Adaptive Deltamodulation (ADM). One transform coding... DPCM system proposed for use on the space shuttle is contained in the IEEE Transactions on Communica- tions, Nov., 1978, p.1671. It is seen that the...delta modu- lator achieves comparable quality at a much lower cost, size, power consumption and at a much improved error sensi- tivity. 65) A DPCM system

  5. Adaptation to direction statistics modulates perceptual discrimination.

    Science.gov (United States)

    Price, Nicholas S C; Prescott, Danielle L

    2012-06-22

    Perception depends on the relative activity of populations of sensory neurons with a range of tunings and response gains. Each neuron's tuning and gain are malleable and can be modified by sustained exposure to an adapting stimulus. Here, we used a combination of human psychophysical testing and models of neuronal population decoding to assess how rapid adaptation to moving stimuli might change neuronal tuning and thereby modulate direction perception. Using a novel motion stimulus in which the direction changed every 10 ms, we demonstrated that 1,500 ms of adaptation to a distribution of directions was capable of modifying human psychophysical direction discrimination performance. Consistent with previous reports, we found perceptual repulsion following adaptation to a single direction. Notably, compared with a uniform adaptation condition in which all motion directions were equiprobable, discrimination was impaired after adaptation to a stimulus comprising only directions ± 30-60° from the discrimination boundary and enhanced after adaptation to the complementary range of directions. Thus, stimulus distributions can be selectively chosen to either impair or improve discrimination performance through adaptation. A neuronal population decoding model incorporating adaptation-induced repulsive shifts in direction tuning curves can account for most aspects of our psychophysical data; however, changes in neuronal gain are sufficient to account for all aspects of our psychophysical data.

  6. Environment-Adaptive Radar Techniques.

    Science.gov (United States)

    1981-02-01

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  7. Intrinsic gain modulation and adaptive neural coding.

    Directory of Open Access Journals (Sweden)

    Sungho Hong

    2008-07-01

    Full Text Available 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 versus 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 fields derived from reverse correlation on a white noise stimulus. Using two conductance-based model neurons that display distinct gain modulation properties through a simple change in parameters, we show that coding properties of both these models quantitatively satisfy the predicted relationships. Our results describe how both variance-dependent gain modulation and adaptive neural computation result from intrinsic nonlinearity.

  8. Comparison of Modulation Techniques Used In WCDMA

    OpenAIRE

    Ciana Barretto,; Olinda Braganza

    2014-01-01

    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 techniq...

  9. Adaptive Combined Source and Channel Decoding with Modulation ...

    African Journals Online (AJOL)

    In this paper, an adaptive system employing combined source and channel decoding with modulation is proposed for slow Rayleigh fading channels. Huffman code is used as the source code and Convolutional code is used for error control. The adaptive scheme employs a family of Convolutional codes of different rates ...

  10. Photoacoustic investigation of QCL modulation techniques

    International Nuclear Information System (INIS)

    Germer, M; Wolff, M

    2010-01-01

    High detection sensitivity and spectral selectivity is important for gas analysers to identify the measured compound and to detect low concentrations. We investigated three different modulation methods - pulse gate modulation, pulse frequency modulation and chopper modulation - for a new pulsed quantum cascade laser based photoacoustic sensor. The spectral selectivity and the detection limit for the three modulation methods are compared by measuring nitric oxide absorption lines and different concentrations. The highest detection sensitivity of 70 ppb was achieved with pulse gate modulation but at the lowest spectral resolution. The highest spectral resolution was achieved with chopper modulation but at the lowest detection sensitivity. It is demonstrated that for the three modulation methods a compromise has to be made between selectivity and sensitivity for each measuring task.

  11. Modulation-Frequency-Specific Adaptation in Awake Auditory Cortex

    Science.gov (United States)

    Beitel, Ralph E.; Vollmer, Maike; Heiser, Marc A.; Schreiner, Christoph E.

    2015-01-01

    Amplitude modulations are fundamental features of natural signals, including human speech and nonhuman primate vocalizations. Because natural signals frequently occur in the context of other competing signals, we used a forward-masking paradigm to investigate how the modulation context of a prior signal affects cortical responses to subsequent modulated sounds. Psychophysical “modulation masking,” in which the presentation of a modulated “masker” signal elevates the threshold for detecting the modulation of a subsequent stimulus, has been interpreted as evidence of a central modulation filterbank and modeled accordingly. Whether cortical modulation tuning is compatible with such models remains unknown. By recording responses to pairs of sinusoidally amplitude modulated (SAM) tones in the auditory cortex of awake squirrel monkeys, we show that the prior presentation of the SAM masker elicited persistent and tuned suppression of the firing rate to subsequent SAM signals. Population averages of these effects are compatible with adaptation in broadly tuned modulation channels. In contrast, modulation context had little effect on the synchrony of the cortical representation of the second SAM stimuli and the tuning of such effects did not match that observed for firing rate. Our results suggest that, although the temporal representation of modulated signals is more robust to changes in stimulus context than representations based on average firing rate, this representation is not fully exploited and psychophysical modulation masking more closely mirrors physiological rate suppression and that rate tuning for a given stimulus feature in a given neuron's signal pathway appears sufficient to engender context-sensitive cortical adaptation. PMID:25878263

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

    Directory of Open Access Journals (Sweden)

    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.

  13. Adaptive and Parallel Computational Techniques in Materials Science

    National Research Council Canada - National Science Library

    Flaherty, Joseph

    1998-01-01

    This Augmentation Award for Science and Engineering Research Training (AASERT) supported research students to work 0 adaptive and parallel computational techniques associated with crystal growth processing...

  14. Size Adaptive Region Based Huffman Compression Technique

    OpenAIRE

    Nandi, Utpal; Mandal, Jyotsna Kumar

    2014-01-01

    A loss-less compression technique is proposed which uses a variable length Region formation technique to divide the input file into a number of variable length regions. Huffman codes are obtained for entire file after formation of regions. Symbols of each region are compressed one by one. Comparisons are made among proposed technique, Region Based Huffman compression technique and classical Huffman technique. The proposed technique offers better compression ratio for some files than other two.

  15. Satellite Media Broadcasting with Adaptive Coding and Modulation

    Directory of Open Access Journals (Sweden)

    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.

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

    KAUST Repository

    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. Adaptive Response Surface Techniques in Reliability Estimation

    DEFF Research Database (Denmark)

    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...

  18. Optimal space communication techniques. [a discussion of delta modulation, pulse code modulation, and phase locked systems

    Science.gov (United States)

    Schilling, D. L.

    1975-01-01

    Encoding of video signals using adaptive delta modulation (DM) was investigated, along with the error correction of DM encoded signals corrupted by thermal noise. Conversion from pulse code modulation to delta modulation was studied; an expression for the signal to noise ratio of the DM signal derived was achieved by employing linear, 2-sample, interpolation between sample points. A phase locked loop using a nonlinear processor in lieu of a loop filter is discussed.

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

    KAUST Repository

    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. The technique of sacral nerve modulation.

    Science.gov (United States)

    Martellucci, J

    2015-04-01

    The aim of this review was to summarize current knowledge and recommendations regarding the technique of implantation of the electrode in performing sacroneuromodulation (SNM) and the available information on programming parameters and implantation algorithms. All English-language articles published from January 1985 to December 2013 that reported the SNM surgical technique and results were considered for inclusion. Data were considered useful for the present review only if related to: (i) peripheral nerve evaluation; (ii) temporary nerve stimulation; (iii) definitive impulse generator placement; and (iv) parameters programming. The literature search revealed 193 potentially relevant studies from initial electronic search terms and eligibility criteria, and these studies were evaluated in detail. In total, 41 studies were included in the final analysis. Of the studies reviewed, the majority (n = 37) were prospective or retrospective case series. Only three randomized clinical trials were eligible for inclusion. Although the technique seems to be standardized, several steps still need to be clarified in order to define the best way to perform the procedure and then to maximize the outcome. Colorectal Disease © 2015 The Association of Coloproctology of Great Britain and Ireland.

  1. Application of adaptive neuro-fuzzy inference system technique in ...

    African Journals Online (AJOL)

    In this paper, an adaptive neuro‐fuzzy inference systems (ANFIS) technique is used in design of MPA. This artificial Intelligence (AI) technique is used in determining the parameters used in the design of a rectangular microstrip patch antenna. The ANFIS has the advantages of expert knowledge of fuzzy inference system ...

  2. Affirmative Action. Module Number 16. Work Experience Program Modules. Coordination Techniques Series.

    Science.gov (United States)

    Shawhan, Carl; Morley, Ray

    This self-instructional module, the last in a series of 16 on techniques for coordinating work experience programs, deals with affirmative action. Addressed in the module are the following topics: the nature of affirmative action legislation and regulations, the role of the teacher-coordinator as a resource person for affirmative action…

  3. Thermally tuneable optical modulator adapted for differential signaling

    Science.gov (United States)

    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.

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

    KAUST Repository

    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.

  5. Seed Pubescence and Shape Modulate Adaptive Responses to Fire Cues.

    Directory of Open Access Journals (Sweden)

    Susana Gómez-González

    Full Text Available Post-fire recruitment by seeds is regarded as an adaptive response in fire-prone ecosystems. Nevertheless, little is known about which heritable seed traits are functional to the main signals of fire (heat and smoke, thus having the potential to evolve. Here, we explored whether three seed traits (pubescence, dormancy and shape and fire regime modulate seed response to fire cues(heat and smoke. As a model study system, we used Helenium aromaticum (Asteraceae, a native annual forb from the Chilean matorral, where fires are anthropogenic. We related seed trait values with fitness responses (germination and survival after exposure to heat-shock and smoke experimental treatments on seeds from 10 H. aromaticum wild populations. We performed a phenotypic selection experiment to examine the relationship of seed traits with post-treatment fitness within a population (adaptive hypothesis. We then explored whether fire frequency in natural habitats was associated with trait expression across populations, and with germination and survival responses to experimental fire-cues. We found that populations subjected to higher fire frequency had, in average, more rounded and pubescent seeds than populations from rarely burned areas. Populations with more rounded and pubescent seeds were more resistant to 80°C heat-shock and smoke treatments.There was correlated selection on seed traits: pubescent-rounded or glabrouscent-elongated seeds had the highest probability of germinating after heat-shock treatments. Seed pubescence and shape in H. aromaticum are heritable traits that modulate adaptive responses to fire. Our results provide new insights into the process of plant adaptation to fire and highlight the relevance of human-made fires as a strong evolutionary agent in the Anthropocene.

  6. Validation of an online replanning technique for prostate adaptive radiotherapy

    International Nuclear Information System (INIS)

    Peng Cheng; Chen Guangpei; Ahunbay, Ergun; Wang Dian; Lawton, Colleen; Li, X Allen

    2011-01-01

    We have previously developed an online adaptive replanning technique to rapidly adapt the original plan according to daily CT. This paper reports the quality assurance (QA) developments in its clinical implementation for prostate cancer patients. A series of pre-clinical validation tests were carried out to verify the overall accuracy and consistency of the online replanning procedure. These tests include (a) phantom measurements of 22 individual patient adaptive plans to verify their accuracy and deliverability and (b) efficiency and applicability of the online replanning process. A four-step QA procedure was established to ensure the safe and accurate delivery of an adaptive plan, including (1) offline phantom measurement of the original plan, (2) online independent monitor unit (MU) calculation for a redundancy check, (3) online verification of plan-data transfer using an in-house software and (4) offline validation of actually delivered beam parameters. The pre-clinical validations demonstrate that the newly implemented online replanning technique is dosimetrically accurate and practically efficient. The four-step QA procedure is capable of identifying possible errors in the process of online adaptive radiotherapy and to ensure the safe and accurate delivery of the adaptive plans. Based on the success of this work, the online replanning technique has been used in the clinic to correct for interfractional changes during the prostate radiation therapy.

  7. Rate adaptive multilevel coded modulation with high coding gain in intensity modulation direct detection optical communication

    Science.gov (United States)

    Xiao, Fei; Liu, Bo; Zhang, Lijia; Xin, Xiangjun; Zhang, Qi; Tian, Qinghua; Tian, Feng; Wang, Yongjun; Rao, Lan; Ullah, Rahat; Zhao, Feng; Li, Deng'ao

    2018-02-01

    A rate-adaptive multilevel coded modulation (RA-MLC) scheme based on fixed code length and a corresponding decoding scheme is proposed. RA-MLC scheme combines the multilevel coded and modulation technology with the binary linear block code at the transmitter. Bits division, coding, optional interleaving, and modulation are carried out by the preset rule, then transmitted through standard single mode fiber span equal to 100 km. The receiver improves the accuracy of decoding by means of soft information passing through different layers, which enhances the performance. Simulations are carried out in an intensity modulation-direct detection optical communication system using MATLAB®. Results show that the RA-MLC scheme can achieve bit error rate of 1E-5 when optical signal-to-noise ratio is 20.7 dB. It also reduced the number of decoders by 72% and realized 22 rate adaptation without significantly increasing the computing time. The coding gain is increased by 7.3 dB at BER=1E-3.

  8. FUMET: A fuzzy network module extraction technique for gene ...

    Indian Academy of Sciences (India)

    FUMET: A fuzzy network module extraction technique for gene expression data. PRIYAKSHI MAHANTA, HASIN AFZAL AHMED, DHRUBA KUMAR BHATTACHARYYA and ASHISH GHOSH http://www.ias.ac.in/jbiosci. J. Biosci. 39(3), June 2014, 351–364, © Indian Academy of Sciences. Supplementary material ...

  9. Application of adaptive antenna techniques to future commercial satellite communication

    Science.gov (United States)

    Ersoy, L.; Lee, E. A.; Matthews, E. W.

    1987-01-01

    The purpose of this contract was to identify the application of adaptive antenna technique in future operational commercial satellite communication systems and to quantify potential benefits. The contract consisted of two major subtasks. Task 1, Assessment of Future Commercial Satellite System Requirements, was generally referred to as the Adaptive section. Task 2 dealt with Pointing Error Compensation Study for a Multiple Scanning/Fixed Spot Beam Reflector Antenna System and was referred to as the reconfigurable system. Each of these tasks was further sub-divided into smaller subtasks. It should also be noted that the reconfigurable system is usually defined as an open-loop system while the adaptive system is a closed-loop system. The differences between the open- and closed-loop systems were defined. Both the adaptive and reconfigurable systems were explained and the potential applications of such systems were presented in the context of commercial communication satellite systems.

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

    KAUST Repository

    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.

  11. Preliminary Studies Of A Phase Modulation Technique For Measuring Chromaticity

    International Nuclear Information System (INIS)

    Tan, C.-Y.

    2006-01-01

    The classical method for measuring chromaticity is to slowly modulate the RF frequency and then measure the betatron tune excursion. The technique that is discussed in this paper instead modulates the phase of the RF and then the chromaticity is obtained by phase demodulating the betatron tune. This technique requires knowledge of the betatron frequency in real time in order for the phase to be demodulated. Fortunately, the Tevatron has a tune tracker based on the phase locked loop principle which fits this requirement. A preliminary study with this technique has showed that it is a promising method for doing continuous chromaticity measurement and raises the possibility of doing successful chromaticity feedback with it

  12. Service Time Analysis for Secondary Packet Transmission with Adaptive Modulation

    KAUST Repository

    Wang, Wen-Jing

    2017-05-12

    Cognitive radio communications can opportunistically access underutilized spectrum for emerging wireless applications. With interweave cognitive implementation, secondary user transmits only if primary user does not occupy the channel and waits for transmission otherwise. Therefore, secondary packet transmission involves both transmission time and waiting time. The resulting extended delivery time (EDT) is critical to the throughput analysis of secondary system. In this paper, we study the EDT of secondary packet transmission with adaptive modulation under interweave implementation to facilitate the delay and throughput analysis of such cognitive radio system. In particular, we propose an analytical framework to derive the probability density functions of EDT considering random-length transmission and waiting slots. We also present selected numerical results to illustrate the mathematical formulations and to verify our analytical approach.

  13. Marginal adaptation of composite resins under two adhesive techniques.

    Science.gov (United States)

    Dačić, Stefan; Veselinović, Aleksandar M; Mitić, Aleksandar; Nikolić, Marija; Cenić, Milica; Dačić-Simonović, Dragica

    2016-11-01

    In the present research, different adhesive techniques were used to set up fillings with composite resins. After the application of etch and rinse or self etch adhesive technique, marginal adaptation of composite fillings was estimated by the length of margins without gaps, and by the microretention of resin in enamel and dentin. The study material consisted of 40 extracted teeth. Twenty Class V cavities were treated with 35% phosphorous acid and restored after rinsing by Adper Single Bond 2 and Filtek Ultimate-ASB/FU 3M ESPE composite system. The remaining 20 cavities were restored by Adper Easy One-AEO/FU 3M ESPE composite system. Marginal adaptation of composite fillings was examined using a scanning electron microscope (SEM). The etch and rinse adhesive technique showed a significantly higher percentage of margin length without gaps (in enamel: 92.5%, in dentin: 57.3%), compared with the self-etch technique with lower percentage of margin length without gaps, in enamel 70.4% (p resin tugs in interprismatic spaces of enamel, while the dentin microretention was composed of adhesive and hybrid layers with resin tugs in dentin canals. In the second technique, resin tugs were rarely seen and a microgap was dominant along the border of restoration margins. The SEM analysis showed a better marginal adaptation of composite resin to enamel and dentin with better microretention when the etch and rinse adhesive procedure was applied. © 2016 Wiley Periodicals, Inc.

  14. Mesh adaptation technique for Fourier-domain fluorescence lifetime imaging

    International Nuclear Information System (INIS)

    Soloviev, Vadim Y.

    2006-01-01

    A novel adaptive mesh technique in the Fourier domain is introduced for problems in fluorescence lifetime imaging. A dynamical adaptation of the three-dimensional scheme based on the finite volume formulation reduces computational time and balances the ill-posed nature of the inverse problem. Light propagation in the medium is modeled by the telegraph equation, while the lifetime reconstruction algorithm is derived from the Fredholm integral equation of the first kind. Stability and computational efficiency of the method are demonstrated by image reconstruction of two spherical fluorescent objects embedded in a tissue phantom

  15. A Novel Monopulse Technique for Adaptive Phased Array Radar

    Directory of Open Access Journals (Sweden)

    Xinyu Zhang

    2017-01-01

    Full Text Available The monopulse angle measuring technique is widely adopted in radar systems due to its simplicity and speed in accurately acquiring a target’s angle. However, in a spatial adaptive array, beam distortion, due to adaptive beamforming, can result in serious deterioration of monopulse performance. In this paper, a novel constrained monopulse angle measuring algorithm is proposed for spatial adaptive arrays. This algorithm maintains the ability to suppress the unwanted signals without suffering from beam distortion. Compared with conventional adaptive monopulse methods, the proposed algorithm adopts a new form of constraint in forming the difference beam with the merit that it is more robust in most practical situations. At the same time, it also exhibits the simplicity of one-dimension monopulse, helping to make this algorithm even more appealing to use in adaptive planar arrays. The theoretical mean and variance of the proposed monopulse estimator is derived for theoretical analysis. Mathematical simulations are formulated to demonstrate the effectiveness and advantages of the proposed algorithm. Both theoretical analysis and simulation results show that the proposed algorithm can outperform the conventional adaptive monopulse methods in the presence of severe interference near the mainlobe.

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

    KAUST Repository

    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.

  17. Compressing Turbulence Effect in FSO using New Modulation Technique

    Directory of Open Access Journals (Sweden)

    Mohamed Nawawi Norizan

    2017-01-01

    Full Text Available Diffusers transmitter modulation to reduce the effect of atmospheric turbulence in free space optical communication system is described in this paper. This technique uses dual transmitters and dual receivers which are using differential mode for detection. The combination of these components produce superior modulation method especially to reduce scintillation index, to overcome signal detection with fix zero threshold and improve power received. In order to improve the performance of free space optical system, these three elements play an important role. The analysis result show that for receiving power dual diffuser modulation at 3 km distance propagation is 4.59dBm compared to conventional OOK using diffuser which only −7.6dBm and equivalent to 3dBm improvement or up to 40 percent better.

  18. Modulation/demodulation techniques for satellite communications. Part 2: Advanced techniques. The linear channel

    Science.gov (United States)

    Omura, J. K.; Simon, M. K.

    1982-01-01

    A theory is presented for deducing and predicting the performance of transmitter/receivers for bandwidth efficient modulations suitable for use on the linear satellite channel. The underlying principle used is the development of receiver structures based on the maximum-likelihood decision rule. The application of the performance prediction tools, e.g., channel cutoff rate and bit error probability transfer function bounds to these modulation/demodulation techniques.

  19. Synchronization Technique for Random Switching Frequency Pulse-Width Modulation

    OpenAIRE

    Apinan Aurasopon; Worawat Sa-ngiavibool

    2008-01-01

    This paper proposes a synchronized random switching frequency pulse width modulation (SRSFPWM). In this technique, the clock signal is used to control the random noise frequency which is produced by the feedback voltage of a hysteresis circuit. These make the triangular carrier frequency equaling to the random noise frequency in each switching period with the symmetrical positive and negative slopes of triangular carrier. Therefore, there is no error voltage in PWM signal. The PSpice simulate...

  20. Modulation/demodulation techniques for satellite communications. Part 1: Background

    Science.gov (United States)

    Omura, J. K.; Simon, M. K.

    1981-01-01

    Basic characteristics of digital data transmission systems described include the physical communication links, the notion of bandwidth, FCC regulations, and performance measurements such as bit rates, bit error probabilities, throughputs, and delays. The error probability performance and spectral characteristics of various modulation/demodulation techniques commonly used or proposed for use in radio and satellite communication links are summarized. Forward error correction with block or convolutional codes is also discussed along with the important coding parameter, channel cutoff rate.

  1. Performance enhanced DDO-OFDM system with adaptively partitioned precoding and single sideband modulation.

    Science.gov (United States)

    Chen, Xi; Feng, Zhenhua; Tang, Ming; Fu, Songnian; Liu, Deming

    2017-09-18

    As a promising solution for short-to-medium transmission systems, direct detection optical orthogonal frequency division multiplexing (DDO-OFDM) or discrete multi-tone (DMT) has been intensively investigated in last decade. Benefitting from the advantages of peak-to-average power (PAPR) reduction and signal-to-noise ratio (SNR) equalization, precoding techniques are widely applied to enhance the performance of DDO-OFDM systems. However, the conventional method of partitioning precoding sets limits the ability of precoding schemes to optimize the SNR variation and the allocation of modulation formats. Thus, the precoding transmission systems are hard to reach the capacity that traditional bit-power loading (BPL) techniques, like the Levin-Campello (LC) algorithm, can achieve. In this paper, we investigate the principle of SNR variation for precoded DDO-OFDM systems and theoretically demonstrate that the SNR equalization effect of precoding techniques is actually determined by the noise equalization process. Based on this fact, we propose an adaptively partitioned precoding (APP) algorithm to unlock the ability to control the SNR of each subcarrier. As demonstrated by the simulation and experimental results, the proposed APP algorithm achieves the transmission capacity as high as the LC algorithm and has nearly 1 dB PAPR reduction. Besides, the look-up table (LUT) operation ensures low complexity of the proposed APP algorithm compared with LC algorithm. To avoid severe chromatic dispersion (CD) induced spectral fading, single sideband (SSB) modulation is also implemented. We find that SSB modulation can reach the capacity of double sideband (DSB) modulation in optical back-to-back (OB2B) configuration by optimizing the modulation index. Therefore, the APP based SSB-DDO-OFDM scheme can sufficiently enhance the performance of cost-sensitive short-to-medium reach optical fiber communication systems.

  2. LFC based adaptive PID controller using ANN and ANFIS techniques

    Directory of Open Access Journals (Sweden)

    Mohamed I. Mosaad

    2014-12-01

    Full Text Available This paper presents an adaptive PID Load Frequency Control (LFC for power systems using Neuro-Fuzzy Inference Systems (ANFIS and Artificial Neural Networks (ANN oriented by Genetic Algorithm (GA. PID controller parameters are tuned off-line by using GA to minimize integral error square over a wide-range of load variations. The values of PID controller parameters obtained from GA are used to train both ANFIS and ANN. Therefore, the two proposed techniques could, online, tune the PID controller parameters for optimal response at any other load point within the operating range. Testing of the developed techniques shows that the adaptive PID-LFC could preserve optimal performance over the whole loading range. Results signify superiority of ANFIS over ANN in terms of performance measures.

  3. An Adaptive Backlight Dimming with the Edge Enhancement Technique

    Science.gov (United States)

    Shiau, Yeuhorng; Li, Chenghan; Huang, Zhaoyuen; Chang, Yungtai

    2017-10-01

    Backlight dimming, which decreases the backlight luminance level and performs pixel compensation, is known as the most effective way to reduce the power consumption of portable electronic devices with LCD. In this paper, we propose an adaptive backlight dimming technique that preserves the quality of details in images even when the backlight luminance of LCD devices is greatly reduced. The proposed backlight dimming method consists of the following two steps: clipped point selection and image compensation. In the first step, to reduce power consumption, the proposed approach selects a suitable clipped point according to the chosen level for a given image based on the maximum and average value. In the second step, several parameters are adaptively chosen according to the characteristic of a given image. These parameters are then used to compensate pixels with an edge enhancement technique. The simulation results show that at the same clipping point the proposed method has higher detailed information than others.

  4. Adaptive differential correspondence imaging based on sorting technique

    Directory of Open Access Journals (Sweden)

    Heng Wu

    2017-04-01

    Full Text Available We develop an adaptive differential correspondence imaging (CI method using a sorting technique. Different from the conventional CI schemes, the bucket detector signals (BDS are first processed by a differential technique, and then sorted in a descending (or ascending order. Subsequently, according to the front and last several frames of the sorted BDS, the positive and negative subsets (PNS are created by selecting the relative frames from the reference detector signals. Finally, the object image is recovered from the PNS. Besides, an adaptive method based on two-step iteration is designed to select the optimum number of frames. To verify the proposed method, a single-detector computational ghost imaging (GI setup is constructed. We experimentally and numerically compare the performance of the proposed method with different GI algorithms. The results show that our method can improve the reconstruction quality and reduce the computation cost by using fewer measurement data.

  5. An Adaptive Hybrid Multiprocessor technique for bioinformatics sequence alignment

    KAUST Repository

    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.

  6. Design techniques for switched capacitor adaptive line equlizer

    OpenAIRE

    Nakayama, Kenji; Sato, Yayoi; Kuranishi, Yoshiaki

    1985-01-01

    This paper describes design techniques for a switched capacitor adaptive line equalizer which is applied to high speed (200 kb/s) digital transmission over analog subscriber loops. An equalizer transfer function is approximated so as to minimize intersymbol interference of an isolated pulse response. Optimum pole-zero location, which is suited to line characteristics in a wide frequency band, is also discussed. In order to attain high accuracy capacitor ratios using a small unit capacitor, ca...

  7. A Q-Modulation Technique for Efficient Inductive Power Transmission.

    Science.gov (United States)

    Kiani, Mehdi; Lee, Byunghun; Yeon, Pyungwoo; Ghovanloo, Maysam

    2015-12-01

    A fully-integrated power management ASIC for efficient inductive power transmission has been presented capable of automatic load transformation using a method, called Q-modulation. Q-modulation is an adaptive scheme that offers load matching against a wide range of loading ( R L ) and coupling distance ( d 23 ) variations in inductive links to maintain high power transfer efficiency (PTE). It is suitable for inductive powering implantable microelectronic devices (IMDs), recharging mobile electronics, and electric vehicles. In Q-modulation, the zero-crossings of the induced current in the receiver (Rx) LC-tank are detected and a low-loss switch chops the Rx LC-tank for part of the power carrier cycle to form a high-Q LC-tank and store the maximum energy, which is then transferred to R L by opening the switch. By adjusting the duty cycle ( D ), the loaded-Q of the Rx LC-tank can be dynamically modulated to compensate for variations in R L . A Q-modulation power management (QMPM) prototype chip was fabricated in a 0.35-μm standard CMOS process, occupying 4.8 mm 2 . In a 1.45 W wireless power transfer setup, using a class-E power amplifier (PA) operating at 2 MHz, the QMPM successfully increased the inductive link PTE and the overall power efficiency by 98.5% and 120.7% at d 23 = 8 cm, respectively, by compensating for 150 Ω variation in R L at D = 45%.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    DEFF Research Database (Denmark)

    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 p...

  11. Optical modulation techniques for analog signal processing and CMOS compatible electro-optic modulation

    Science.gov (United States)

    Gill, Douglas M.; Rasras, Mahmoud; Tu, Kun-Yii; Chen, Young-Kai; White, Alice E.; Patel, Sanjay S.; Carothers, Daniel; Pomerene, Andrew; Kamocsai, Robert; Beattie, James; Kopa, Anthony; Apsel, Alyssa; Beals, Mark; Mitchel, Jurgen; Liu, Jifeng; Kimerling, Lionel C.

    2008-02-01

    Integrating electronic and photonic functions onto a single silicon-based chip using techniques compatible with mass-production CMOS electronics will enable new design paradigms for existing system architectures and open new opportunities for electro-optic applications with the potential to dramatically change the management, cost, footprint, weight, and power consumption of today's communication systems. While broadband analog system applications represent a smaller volume market than that for digital data transmission, there are significant deployments of analog electro-optic systems for commercial and military applications. Broadband linear modulation is a critical building block in optical analog signal processing and also could have significant applications in digital communication systems. Recently, broadband electro-optic modulators on a silicon platform have been demonstrated based on the plasma dispersion effect. The use of the plasma dispersion effect within a CMOS compatible waveguide creates new challenges and opportunities for analog signal processing since the index and propagation loss change within the waveguide during modulation. We will review the current status of silicon-based electrooptic modulators and also linearization techniques for optical modulation.

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

    Science.gov (United States)

    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.

  13. Superpenetration optical microscopy by iterative multiphoton adaptive compensation technique.

    Science.gov (United States)

    Tang, Jianyong; Germain, Ronald N; Cui, Meng

    2012-05-29

    Biological tissues are rarely transparent, presenting major challenges for deep tissue optical microscopy. The achievable imaging depth is fundamentally limited by wavefront distortions caused by aberration and random scattering. Here, we report an iterative wavefront compensation technique that takes advantage of the nonlinearity of multiphoton signals to determine and compensate for these distortions and to focus light inside deep tissues. Different from conventional adaptive optics methods, this technique can rapidly measure highly complicated wavefront distortions encountered in deep tissue imaging and provide compensations for not only aberration but random scattering. The technique is tested with a variety of highly heterogeneous biological samples including mouse brain tissue, skull, and lymph nodes. We show that high quality three-dimensional imaging can be realized at depths beyond the reach of conventional multiphoton microscopy and adaptive optics methods, albeit over restricted distances for a given correction. Moreover, the required laser excitation power can be greatly reduced in deep tissues, deviating from the power requirement of ballistic light excitation and thus significantly reducing photo damage to the biological tissue.

  14. Aerosol model selection and uncertainty modelling by adaptive MCMC technique

    Directory of Open Access Journals (Sweden)

    M. Laine

    2008-12-01

    Full Text Available We present a new technique for model selection problem in atmospheric remote sensing. The technique is based on Monte Carlo sampling and it allows model selection, calculation of model posterior probabilities and model averaging in Bayesian way.

    The algorithm developed here is called Adaptive Automatic Reversible Jump Markov chain Monte Carlo method (AARJ. It uses Markov chain Monte Carlo (MCMC technique and its extension called Reversible Jump MCMC. Both of these techniques have been used extensively in statistical parameter estimation problems in wide area of applications since late 1990's. The novel feature in our algorithm is the fact that it is fully automatic and easy to use.

    We show how the AARJ algorithm can be implemented and used for model selection and averaging, and to directly incorporate the model uncertainty. We demonstrate the technique by applying it to the statistical inversion problem of gas profile retrieval of GOMOS instrument on board the ENVISAT satellite. Four simple models are used simultaneously to describe the dependence of the aerosol cross-sections on wavelength. During the AARJ estimation all the models are used and we obtain a probability distribution characterizing how probable each model is. By using model averaging, the uncertainty related to selecting the aerosol model can be taken into account in assessing the uncertainty of the estimates.

  15. Modulation/demodulation techniques for satellite communications. Part 3: Advanced techniques. The nonlinear channel

    Science.gov (United States)

    Omura, J. K.; Simon, M. K.

    1982-01-01

    A theory for deducing and predicting the performance of transmitter/receivers for bandwidth efficient modulations suitable for use on the nonlinear satellite channel is presented. The underlying principle used throughout is the development of receiver structures based on the maximum likelihood decision rule and aproximations to it. The bit error probability transfer function bounds developed in great detail in Part 4 is applied to these modulation/demodulation techniques. The effects of the various degrees of receiver mismatch are considered both theoretically and by numerous illustrative examples.

  16. Intensity-modulated radiation therapy clinical evidence and techniques

    CERN Document Server

    Nishimura, Yasumasa

    2015-01-01

    Successful clinical use of intensity-modulated radiation therapy (IMRT) represents a significant advance in radiation oncology. Because IMRT can deliver high-dose radiation to a target with a reduced dose to the surrounding organs, it can improve the local control rate and reduce toxicities associated with radiation therapy. Since IMRT began being used in the mid-1990s, a large volume of clinical evidence of the advantages of IMRT has been collected. However, treatment planning and quality assurance (QA) of IMRT are complicated and difficult for the clinician and the medical physicist. This book, by authors renowned for their expertise in their fields, provides cumulative clinical evidence and appropriate techniques for IMRT for the clinician and the physicist. Part I deals with the foundations and techniques, history, principles, QA, treatment planning, radiobiology and related aspects of IMRT. Part II covers clinical applications with several case studies, describing contouring and dose distribution with cl...

  17. Comparative Study of Modulation Techniques for Two-Level Voltage Source Inverters

    Directory of Open Access Journals (Sweden)

    Barry W. Williams

    2016-06-01

    Full Text Available A detailed comparative study of modulation techniques for single and three phase dc-ac inverters is presented.  Sinusoidal Pulse Width Modulation, Triplen Sinusoidal Pulse Width Modulation, Space Vector Modulation, Selective Harmonic Elimination and Wavelet Modulation are assessed and compared in terms of maximum fundamental output, harmonic performance, switching losses and operational mode.  The presented modulation techniques are applied to single and three phase voltage source inverters and are simulated using SIMULINK.  The simulation results clarify the inverter performance achieved using the different modulations techniques.

  18. Intensity Modulated Radiation Therapy. Development of the technique

    International Nuclear Information System (INIS)

    Rafailovici, L.; Alva, R.; Chiozza, J.; Donato, H.; Falomo, S.; Cardiello, C.; Furia, O.; Martinez, A.; Filomia, M.L.; Sansogne, R.; Arbiser, S.; Dosoretz, B.

    2008-01-01

    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) [es

  19. Adaptive Atmospheric Modeling Key Techniques in Grid Generation, Data Structures, and Numerical Operations with Applications

    CERN Document Server

    Behrens, Jörn

    2006-01-01

    Gives an overview and guidance in the development of adaptive techniques for atmospheric modeling. This book covers paradigms of adaptive techniques, such as error estimation and adaptation criteria. Considering applications, it demonstrates several techniques for discretizing relevant conservation laws from atmospheric modeling.

  20. Lymphogammagraphy. An adaptive technique to specific clinical problems

    International Nuclear Information System (INIS)

    Rojas, Juan Carlos; Llamas, Augusto E; De los Reyes, Amelia; Martinez, Maria Cristina

    2000-01-01

    Lymphoscintigraphy (LS) is an accurate and safe procedure for the evaluation of lymph nodes, many of which remain occult to other imaging techniques. Not only lymphatic pathways, but also the functional condition of the lymphatic channels and the localization of lymphatic basins can be assessed with LS. We will illustrate the utility of the technique in different clinical settings, concerning two patients recently studied at the National Cancer Institute. In the first case a patient previously diagnosed with a testicular teratocarcinoma that presented with ascites. The LS showed a chyloperitoneum, leading the clinicians to with old further treatment given the lymphatic nature of the ascites as opposed to a malignant origin. In the second patient the LS illustrated the adaptability of the lymphatic system to a chronic insult (suture of Pecquet's cistem) by lymphatic flows diversion through paralumbar channels. In this patient LS was combined with a peritoneal scintigraphy to demonstrate permeability through a peritoneovenous bypass; incidentally, a peritoneopleural shunt was diagnosed. LS permit the visualization of lymphatic channels and their functional derangements in an easy, minimally invasive way, not routinely achievable by other imaging techniques |

  1. Spectral analysis techniques for characterizing cadmium zinc telluride polarization modulators

    Science.gov (United States)

    FitzGerald, William R.; Taherion, Saeid; Kumar, F. Joseph; Giles, David; Hore, Dennis K.

    2018-04-01

    The low frequency electro-optic characteristics of cadmium zinc telluride are demonstrated in the mid-infrared, in the spectral range 2.5-11 μm. Conventional methods for characterizing the dynamic response by monitoring the amplitude of the time-varying light intensity do not account for spatial variation in material properties. In such cases, a more revealing method involves monitoring two distinct frequency components in order to characterize the dynamic and static contributions to the optical retardation. We demonstrate that, while this method works well for a ZnSe photo-elastic modulator, it does not fully capture the response of a cadmium zinc telluride electro-optic modulator. Ultimately, we show that acquiring the full waveform of the optical response enables a model to be created that accounts for inhomogeneity in the material that results in an asymmetric response with respect to the polarity of the driving voltage. This technique is applicable to broadband and fixed-wavelength applications in a variety of spectral ranges.

  2. High Dimensional Modulation and MIMO Techniques for Access Networks

    DEFF Research Database (Denmark)

    Binti Othman, Maisara

    Exploration of advanced modulation formats and multiplexing techniques for next generation optical access networks are of interest as promising solutions for delivering multiple services to end-users. This thesis addresses this from two different angles: high dimensionality carrierless...... the capacity per wavelength of the femto-cell network. Bit rate up to 1.59 Gbps with fiber-wireless transmission over 1 m air distance is demonstrated. The results presented in this thesis demonstrate the feasibility of high dimensionality CAP in increasing the number of dimensions and their potentially......) optical access network. 2 X 2 MIMO RoF employing orthogonal frequency division multiplexing (OFDM) with 5.6 GHz RoF signaling over all-vertical cavity surface emitting lasers (VCSEL) WDM passive optical networks (PONs). We have employed polarization division multiplexing (PDM) to further increase...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Effects of modulation techniques on the input current interharmonics of Adjustable Speed Drives

    DEFF Research Database (Denmark)

    Soltani, Hamid; Davari, Pooya; Zare, Firuz

    2018-01-01

    operation of the grid. This paper presents the effect of the symmetrical regularly sampled Space Vector Modulation (SVM) and Discontinuous Pulse Width Modulation-30olag (DPWM2) techniques, as the most popular modulation methods in the ASD applications, on the drive’s input current interharmonic magnitudes....... Further investigations are also devoted to the cases, where the Random Modulation (RM) technique is applied on the selected modulation strategies. The comparative results show that how different modulation techniques can influence the ASD’s input current interharmonics and consequently may...

  5. Variable and Adaptive Coded Modulation for Cognitive Networking

    Data.gov (United States)

    National Aeronautics and Space Administration — In this task, our objective is to design and implement a variable coded modulation (VCM) system capable of significantly increasing the data return of Space-to-Earth...

  6. Adaptive MultiCAP modulation for short range VCSEL based transmissions

    DEFF Research Database (Denmark)

    Puerta Ramírez, Rafael; Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

    2016-01-01

    We propose an adaptive approach for multi-band carrierless amplitude/phase modulation, with advantages of adaptive bit rate and energy savings. Successful performance is demonstrated on 850 nm multi-mode VCSEL based transmissions achieving up to 40.6 Gb/s....

  7. Parallel implementation of the adaptive neighborhood contrast enhancement technique

    Science.gov (United States)

    Alto, Hilary; Gavrilov, Dmitri; Rangayyan, Rangaraj M.

    1999-10-01

    An adaptive neighborhood contrast enhancement (ANCE) technique was developed to improve the perceptibility of features in digitized mammographic images for use in breast cancer screening. The computationally intensive algorithm was implemented on a cluster of 30 DEC Alpha processors using the message passing interface. The parallel implementation of the ANCE technique utilizes histogram- based image partitioning with each partition consisting of pixels of the same gray-level value regardless of their location in the image. The master processor allots one set of pixels to each slave processor. The slave returns the results to the master, and the master than sends a new set of pixels to the slave for processing. This procedure continues until there are no sets of pixels left. The subdivision of the original image based on gray-level values guarantees that slave processors do not process the same pixel, and is specifically well-suited to the characteristics of the ANCE algorithm. The parallelism value of the problem is approximately 16, i.e., the performance does not improve significantly when more than 16 processors are used. The result is a substantial improvement in processing time, leading to the enhancement of 4 K X 4 K pixel images in the range of 20 to 60 seconds.

  8. Optical techniques to understand biofunctional adaptation in human dentine

    Science.gov (United States)

    Kishen, Anil; Asundi, Anand K.

    2004-08-01

    Human tooth structure in the oral environment is subjected to mechanical forces and thermal fluctuations. Dentine, the major component of the tooth structure, is a bio-composite, mainly composed of a highly mineralized phase and a collagenous phase. When subjected to changes in load and/or temperature, dentine will experience stresses and strains distribution within their structure. Though such effects are found to cause deleterious effects on artificial dental restorations, biological structures such as dentine seem to posses an inherent ability to adapt to functional thermo-mechanical loads. Optical techniques enable visualization and quantification of deformation, strain and stress on dental structures and provide a better understanding on their thermo-mechanical response. In this study 2-dimensional and 3-dimensional digital photoelasticity, digital moiré interferometry and Electronic Speckle Pattern Interferometry (ESPI) are all shown to be quite promising in this application. This paper will highlight these techniques and the corresponding applications. These experiments will aid in designing and development of better dental restorations and implants in clinical practice.

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

    KAUST Repository

    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.

  10. Water System Adaptation To Hydrological Changes: Module 7, Adaptation Principles and Considerations

    Science.gov (United States)

    This course will introduce students to the fundamental principles of water system adaptation to hydrological changes, with emphasis on data analysis and interpretation, technical planning, and computational modeling. Starting with real-world scenarios and adaptation needs, the co...

  11. A fuzzy network module extraction technique for gene expression data

    Indian Academy of Sciences (India)

    2014-05-01

    May 1, 2014 ... organization. 1.25e−9. Regulation of neurological system process. 1.76e−9. Protein tyrosine kinase activity. 8.22e−9. Protein autophosphorylation. 2.78e−8. Table 9. Q-value of one of the network modules of Dataset 1. Module. GO annotation. Q-value. Module 1. Anatomical structure formation involved.

  12. FUMET: A fuzzy network module extraction technique for gene ...

    Indian Academy of Sciences (India)

    Supplementary figure 1. (A): Visualization of one of the network modules by GeneMania for dataset 4 (B): Visualization of one of the network modules by GeneMania for dataset 1 (C): Visualization of one of the network modules by GeneMania for dataset 3.

  13. Adaptive Coding and Modulation Experiment With NASA's Space Communication and Navigation Testbed

    Science.gov (United States)

    Downey, Joseph; Mortensen, Dale; Evans, Michael; Briones, Janette; Tollis, Nicholas

    2016-01-01

    National Aeronautics and Space Administration (NASA)'s Space Communication and Navigation Testbed is an advanced integrated communication payload on the International Space Station. This paper presents results from an adaptive coding and modulation (ACM) experiment over S-band using a direct-to-earth link between the SCaN Testbed and the Glenn Research Center. The testing leverages the established Digital Video Broadcasting Second Generation (DVB-S2) standard to provide various modulation and coding options, and uses the Space Data Link Protocol (Consultative Committee for Space Data Systems (CCSDS) standard) for the uplink and downlink data framing. The experiment was conducted in a challenging environment due to the multipath and shadowing caused by the International Space Station structure. Several approaches for improving the ACM system are presented, including predictive and learning techniques to accommodate signal fades. Performance of the system is evaluated as a function of end-to-end system latency (round-trip delay), and compared to the capacity of the link. Finally, improvements over standard NASA waveforms are presented.

  14. Increasing the bit rate in OCDMA systems using pulse position modulation techniques.

    Science.gov (United States)

    Arbab, Vahid R; Saghari, Poorya; Haghi, Mahta; Ebrahimi, Paniz; Willner, Alan E

    2007-09-17

    We have experimentally demonstrated two novel pulse position modulation techniques, namely Double Pulse Position Modulation (2-PPM) and Differential Pulse Position Modulation (DPPM) in Time-Wavelength OCDMA systems that will operate at a higher bit rate compared to traditional OOK-OCDMA systems with the same bandwidth. With 2-PPM technique, the number of active users will be more than DPPM while their bit rate is almost the same. Both techniques provide variable quality of service in OCDMA networks.

  15. Climate change adaptation: Boosting quinoa production using nuclear techniques

    International Nuclear Information System (INIS)

    Dixit, Aabha

    2015-01-01

    In the battle to help developing countries overcome threats from declining food production caused by climate change, one species of edible grain-like crop has caught international attention because of its unique nutritional value. New and improved varieties of quinoa, historically grown in the highlands of South America, will be made available to farmers in mutations adapted to challenging environments in Bolivia and Peru. Increased genetic diversity is the result of the use of nuclear techniques in collaboration with the IAEA and the Food and Agriculture Organization of the United Nations (FAO), said L. Gomez-Pando, Principal Professor and Head of the Cereals and Native Grains Research programme at the National Agrarian University of La Molina in Peru. “There are 64 mutant lines of quinoa selected by yield potential and quality for the market,” he said. “These mutant lines will be further evaluated and the best lines will be released as new varieties in 2015–2016.”

  16. Modulation of allele leakiness and adaptive mutability in Escherichia ...

    Indian Academy of Sciences (India)

    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 rpsLЗ (streptomycin-sensitive) derivative of the Escherichia coli strain AB1157 greatly enhances their adaptive mutability under selection.

  17. Modulation of allele leakiness and adaptive mutability in Escherichia ...

    Indian Academy of Sciences (India)

    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.

  18. Motor modules during adaptation to walking in a powered ankle exoskeleton.

    Science.gov (United States)

    Jacobs, Daniel A; Koller, Jeffrey R; Steele, Katherine M; Ferris, Daniel P

    2018-01-03

    Modules of muscle recruitment can be extracted from electromyography (EMG) during motions, such as walking, running, and swimming, to identify key features of muscle coordination. These features may provide insight into gait adaptation as a result of powered assistance. The aim of this study was to investigate the changes (module size, module timing and weighting patterns) of surface EMG data during assisted and unassisted walking in an powered, myoelectric, ankle-foot orthosis (ankle exoskeleton). Eight healthy subjects wore bilateral ankle exoskeletons and walked at 1.2 m/s on a treadmill. In three training sessions, subjects walked for 40 min in two conditions: unpowered (10 min) and powered (30 min). During each session, we extracted modules of muscle recruitment via nonnegative matrix factorization (NNMF) from the surface EMG signals of ten muscles in the lower limb. We evaluated reconstruction quality for each muscle individually using R 2 and normalized root mean squared error (NRMSE). We hypothesized that the number of modules needed to reconstruct muscle data would be the same between conditions and that there would be greater similarity in module timings than weightings. Across subjects, we found that six modules were sufficient to reconstruct the muscle data for both conditions, suggesting that the number of modules was preserved. The similarity of module timings and weightings between conditions was greater then random chance, indicating that muscle coordination was also preserved. Motor adaptation during walking in the exoskeleton was dominated by changes in the module timings rather than module weightings. The segment number and the session number were significant fixed effects in a linear mixed-effect model for the increase in R 2 with time. Our results show that subjects walking in a exoskeleton preserved the number of modules and the coordination of muscles within the modules across conditions. Training (motor adaptation within the session and

  19. Weather Effect on Photovoltaic Module Adaptation in Coastal Areas

    OpenAIRE

    emetere, moses; akinyemi, marvel

    2016-01-01

    The climatic factors in the coastal areas are cogent in planning a stable and functional solar farm. The experiment performed in this study entails a day-to-day solar radiation pattern in coastal areas. The results show that the solar radiation pattern in coastal region portends danger to the performance of solar PV module and its lifecycle. The solar radiation pattern in coastal areas was traced to the solar sectional shading theory which was summarized and explained.

  20. An MSc Course Module: Wind Turbine Measurement Techniques

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose; Pedersen, Knud Ole Helgesen

    2005-01-01

    The 2-year MSc in Wind power engineering at the Technical University of Denmark comprises modules from core engineering teaching and from other modules specifically designed to the MSc. This Note outlines the content of such a specific module on the subject of wind turbine measurement. The lectures......, practical exercises and work related to measurements from an operating 500 kW turbine are described....

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  2. Water System Adaptation to Hydrological Changes: Module 1, Introduction to Water System Adaptation

    Science.gov (United States)

    Contemporary water management requires resilience, the ability to meet ever increasing water needs, and capacity to adapt to abrupt or transient changes in water quality and availability. For this purpose, effective adaptation to extreme hydrological events (e.g. intense storms, ...

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

    Science.gov (United States)

    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,…

  4. Impact of Self-Interference on the Performance of Joint Partial RAKE Receiver and Adaptive Modulation

    KAUST Repository

    Nam, Sung Sik

    2016-11-23

    In this paper, we investigate the impact of self-interference on the performance of a joint partial RAKE (PRAKE) receiver and adaptive modulation over both independent and identically distributed and independent but non-identically distributed Rayleigh fading channels. To better observe the impact of self-interference, our approach starts from considering the signal to interference plus noise ratio. Specifically, we accurately analyze the outage probability, the average spectral efficiency, and the average bit error rate as performance measures in the presence of self-interference. Several numerical and simulation results are selected to present the performance of the joint PRAKE receiver and adaptive modulation subject to self-interference.

  5. Spinal glia modulate both adaptive and pathological processes

    Science.gov (United States)

    Vichaya, Elisabeth G.; Baumbauer, Kyle M.; Carcoba, Luis M.; Grau, James W.; Meagher, Mary W.

    2009-01-01

    Recent research indicates that glial cells control complex functions within the nervous system. For example, it has been shown that glial cells contribute to the development of pathological pain, the process of long-term potentiation, and the formation of memories. These data suggest that glial cell activation exerts both adaptive and pathological effects within the CNS. To extend this line of work, the present study investigated the role of glia in spinal learning and spinal learning deficits using the spinal instrumental learning paradigm. In this paradigm rats are transected at the second thoracic vertebra (T2) and given shock to one hind limb whenever the limb is extended (controllable shock). Over time these subjects exhibit an increase in flexion duration that reduces net shock exposure. However, when spinalized rats are exposed to uncontrollable shock or inflammatory stimuli prior to testing with controllable shock, they exhibit a learning deficit. To examine the role of glial in this paradigm, spinal glial cells were pharmacologically inhibited through the use of fluorocitrate. Our results indicate that glia are involved in the acquisition, but not maintenance, of spinal learning. Furthermore, the data indicate that glial cells are involved in the development of both shock and inflammation-induced learning deficits. These findings are consistent with prior research indicating that glial cells are involved in both adaptive and pathological processes within the spinal cord. PMID:19435601

  6. Comparison of a new noncoplanar intensity-modulated radiation therapy technique for craniospinal irradiation with 3 coplanar techniques

    DEFF Research Database (Denmark)

    Hansen, Anders T; Lukacova, Slavka; Lassen-Ramshad, Yasmin A.

    2015-01-01

    When standard conformal x-ray technique for craniospinal irradiation is used, it is a challenge to achieve satisfactory dose coverage of the target including the area of the cribriform plate, while sparing organs at risk. We present a new intensity-modulated radiation therapy (IMRT), noncoplanar...... patient using the noncoplanar IMRT-based technique, a coplanar IMRT-based technique, and a coplanar volumetric-modulated arch therapy (VMAT) technique. Dosimetry data for all patients were compared with the corresponding data from the conventional treatment plans. The new noncoplanar IMRT technique...... substantially reduced the mean dose to organs at risk compared with the standard radiation technique. The 2 other coplanar techniques also reduced the mean dose to some of the critical organs. However, this reduction was not as substantial as the reduction obtained by the noncoplanar technique. Furthermore...

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

    Science.gov (United States)

    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.

  8. Heterodyne technique for measuring the amplitude and phase transfer functions of an optical modulator

    DEFF Research Database (Denmark)

    Romstad, Francis Pascal; Birkedal, Dan; Mørk, Jesper

    2002-01-01

    In this letter, we propose a technique based on heterodyne detection for accurately and simultaneously measuring the amplitude and phase transfer functions of an optical modulator. The technique is used to characterize an InGaAsp multiple quantum-well electroabsorption modulator. From...

  9. A Method for Eliminating Beam Steering Error for the Modulated Absorption-Emission Thermometry Technique

    Science.gov (United States)

    2015-01-01

    Beam Steering Error for the Modulated Absorption-Emission Thermometry Technique 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d...Jan 2015. PA#14562. 14. ABSTRACT Modulated absorption-emission thermometry (MAET) is a non-intrusive, radiometric technique for measuring line-of...ANSI Std. 239.18 1 Integrity  Service  Excellence A Method for Eliminating Beam Steering Error for Modulated Absorption- Emission Thermometry

  10. Joint Adaptive Modulation and Combining for Hybrid FSO/RF Systems

    KAUST Repository

    Rakia, Tamer

    2015-11-12

    In this paper, we present and analyze a new transmission scheme for hybrid FSO/RF communication system based on joint adaptive modulation and adaptive combining. Specifically, the data rate on the FSO link is adjusted in discrete manner according to the FSO link\\'s instantaneous received signal-to-noise-ratio (SNR). If the FSO link\\'s quality is too poor to maintain the target bit-error-rate, the system activates the RF link along with the FSO link. When the RF link is activated, simultaneous transmission of the same modulated data takes place on both links, where the received signals from both links are combined using maximal ratio combining scheme. In this case, the data rate of the system is adjusted according to the instantaneous combined SNRs. Novel analytical expression for the cumulative distribution function (CDF) of the received SNR for the proposed adaptive hybrid system is obtained. This CDF expression is used to study the spectral and outage performances of the proposed adaptive hybrid FSO/RF system. Numerical examples are presented to compare the performance of the proposed adaptive hybrid FSO/RF system with that of switch-over hybrid FSO/RF and FSO-only systems employing the same adaptive modulation schemes. © 2015 IEEE.

  11. Configurable multiplier modules for an adaptive computing system

    Directory of Open Access Journals (Sweden)

    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.

  12. Open-Loop Wide-Bandwidth Phase Modulation Techniques

    Directory of Open Access Journals (Sweden)

    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.

  13. Wavelength reused bidirectional transmission of adaptively modulated optical OFDM signals in WDM-PONs incorporating SOA and RSOA intensity modulators.

    Science.gov (United States)

    Wei, J L; Hugues-Salas, E; Giddings, R P; Jin, X Q; Zheng, X; Mansoor, S; Tang, J M

    2010-05-10

    Detailed numerical investigations are undertaken of wavelength reused bidirectional transmission of adaptively modulated optical OFDM (AMOOFDM) signals over a single SMF in a colorless WDM-PON incorporating a semiconductor optical amplifier (SOA) intensity modulator and a reflective SOA (RSOA) intensity modulator in the optical line termination and optical network unit, respectively. A comprehensive theoretical model describing the performance of such network scenarios is, for the first time, developed, taking into account dynamic optical characteristics of SOA and RSOA intensity modulators as well as the effects of Rayleigh backscattering (RB) and residual downstream signal-induced crosstalk. The developed model is rigorously verified experimentally in RSOA-based real-time end-to-end OOFDM systems at 7.5 Gb/s. It is shown that the RB noise and crosstalk effects are dominant factors limiting the maximum achievable downstream and upstream transmission performance. Under optimum SOA and RSOA operating conditions as well as practical downstream and upstream optical launch powers, 10 Gb/s downstream and 6 Gb/s upstream over 40 km SMF transmissions of conventional double sideband AMOOFDM signals are feasible without utilizing in-line optical amplification and chromatic dispersion compensation. In particular, the aforementioned transmission performance can be improved to 23 Gb/s downstream and 8 Gb/s upstream over 40 km SMFs when single sideband subcarrier modulation is adopted in the downstream systems. (c) 2010 Optical Society of America.

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

    KAUST Repository

    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.

  15. Pain adaptability in individuals with chronic musculoskeletal pain is not associated with conditioned pain modulation

    DEFF Research Database (Denmark)

    Wan, Dawn Wong Lit; Arendt-Nielsen, Lars; Wang, Kelun

    2018-01-01

    (MSK). CPTs at 2°C and 7°C were used to assess the status of pain adaptability in participants with either chronic non-specific low back pain or knee osteoarthritis. The participants' potency of conditioned pain modulation (CPM) and local inhibition were measured. The strengths of pain adaptability...... at both CPTs were highly correlated. PA and PNA did not differ in their demographics, pain thresholds from thermal and pressure stimuli, or potency of local inhibition or CPM. PA reached their maximum pain faster than PNA (t41=-2.76, p... days whereas PNA did not (F (6,246) = 3.01, p = 0.01). The dichotomy of pain adaptability exists in MSK patients. Consistent with the healthy human study, the strength of pain adaptability and potency of CPM are not related. Pain adaptability could be another form of endogenous pain inhibition which...

  16. Modulation techniques for deep-space pulse-position modulation (PPM) optical communication

    Science.gov (United States)

    Rayman, Marc D.; Robinson, Deborah L.

    1988-01-01

    The extremely energy-efficient pulse-position modulation (PPM) format is being actively developed as a basis for optical communications with deep-space probes. Attention is presently given to different modulation schemes for the efficient production of laser pulses over a broad range of repetition rates. Both Q-switching and cavity dumping modulation methods are available for the envisioned diode-pumped Nd:YAG laser source. Numerical calculation results are presented for cavity-dumping.

  17. Underwater wireless optical MIMO system with spatial modulation and adaptive power allocation

    Science.gov (United States)

    Huang, Aiping; Tao, Linwei; Niu, Yilong

    2018-04-01

    In this paper, we investigate the performance of underwater wireless optical multiple-input multiple-output communication system combining spatial modulation (SM-UOMIMO) with flag dual amplitude pulse position modulation (FDAPPM). Channel impulse response for coastal and harbor ocean water links are obtained by Monte Carlo (MC) simulation. Moreover, we obtain the closed-form and upper bound average bit error rate (BER) expressions for receiver diversity including optical combining, equal gain combining and selected combining. And a novel adaptive power allocation algorithm (PAA) is proposed to minimize the average BER of SM-UOMIMO system. Our numeric results indicate an excellent match between the analytical results and numerical simulations, which confirms the accuracy of our derived expressions. Furthermore, the results show that adaptive PAA outperforms conventional fixed factor PAA and equal PAA obviously. Multiple-input single-output system with adaptive PAA obtains even better BER performance than MIMO one, at the same time reducing receiver complexity effectively.

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

    DEFF Research Database (Denmark)

    Karinou, Fotini; Borkowski, Robert; Zibar, Darko

    2013-01-01

    We experimentally assess the performance of a 64 × 64 optical switch fabric used for ns-speed optical cell switching in supercomputer optical interconnects. More specifically, we study four alternative modulation formats and detection schemes, namely, 10-Gb/s nonreturn-to-zero differential phase-...

  19. Shock capturing techniques for hphp-adaptive finite elements

    Czech Academy of Sciences Publication Activity Database

    Hierro, A.; Kůs, Pavel; Badia, S.

    2016-01-01

    Roč. 309, 1 September (2016), s. 532-553 ISSN 0045-7825 Institutional support: RVO:67985840 Keywords : hphp-adaptivity * discontinuous Galerkin * shock capturing Subject RIV: BA - General Mathematics Impact factor: 3.949, year: 2016 http://www.sciencedirect.com/science/article/pii/S0045782516305862

  20. Shock capturing techniques for hphp-adaptive finite elements

    OpenAIRE

    Hierro, A.; Kůs, P. (Pavel); Badia, S.

    2016-01-01

    The aim of this work is to propose an hp-adaptive algorithm for discontinuous Galerkin methods that is capable to detect the discontinuities and sharp layers and avoid the spurious oscillation of the solution around them. In order to control the spurious oscillations, artificial viscosity is used with the particularity that it is only applied around the layers where the solution changes abruptly. To do so, a novel troubled-cell detector has been developed in order to mark the elements around ...

  1. Modulation/demodulation techniques for satellite communications. Part 4: Appendices

    Science.gov (United States)

    Omura, J. K.; Simon, M. K.

    1981-01-01

    The use of the Viterbi algorithm in a general context is examined. The generalized transfer function bounds are given which permit the following applications to be carried out: maximum likelihood demodulation of such bandwidth modulations as minimum-shift-keying and continuous phase frequency-shift-keying, demodulation of intersymbol interference and partial response signals, estimation and smoothing, and simultaneous phase synchronization, and data detection. Sufficient conditions are reviewed for tightening Chernoff and Rhattacharyya bounds.

  2. Electro-optic modulation measurement technique and enhancement

    DEFF Research Database (Denmark)

    Jacobsen, Rune Shim

    2005-01-01

    indeks bølgeleder blev påbegyndt. Når denne koefficient opnås i en sådan bølgeleder vil fremtidige forsøg kunne fastlægge hvor stor den inducerede ikke-lineare koefficient i silicium kan blive. Fremtidige forsøg vil også fastlægge om den inducerede effekt eksisterer for hurtig elektrisk modulation....

  3. Evaluation of mass transfer in a novel hollow fiber module design using an electrochemical technique

    Directory of Open Access Journals (Sweden)

    L. S. de França Neta

    Full Text Available Abstract The mass transfer coefficient (K L determined using an electrochemical technique was used in this work as a parameter to evaluate the hydrodynamics of hollow fiber membrane modules. A new microfiltration module configuration was investigated, taking advantage of the hydrocyclone concept aimed at reducing the concentration of the polarization layer near the membrane surface promoted by the centrifugal field. The mass transfer coefficient for the new configuration was compared with that of a conventional longitudinal module. The experimental determination of K L was obtained by monitoring the electrochemical reactions that occur at the electrode surface under mass transfer-limiting conditions. The performance of the microfiltration modules, both hybrid and longitudinal, was evaluated based on parameters such as packing density and fluid flow regimes. The results achieved for the mass transfer coefficient with the electrochemical technique allowed for performance evaluations of the proposed new module configuration and a comparison with the longitudinal module.

  4. Nuclear Technology. Course 26: Nondestructive Examination (NDE) Techniques I. Module 26-5, Fundamentals of Radiography.

    Science.gov (United States)

    Groseclose, Richard

    This fifth in a series of seven modules for a course titled Nondestructive Examination (NDE) Techniques I explains the radiographic process, from radiation source selection to equipment and specimen selection and arrangement, and film processing. The module follows a typical format that includes the following sections: (1) introduction, (2) module…

  5. Nuclear Technology. Course 26: Nondestructive Examination (NDE) Techniques I. Module 26-6, Radiography Inspection.

    Science.gov (United States)

    Pelton, Rick; Espy, John

    This sixth in a series of seven modules for a course titled Nondestructive Examination (NDE) Techniques I explains radiographic inspection as a means of nondestructively examining components, assemblies, structures, and fabricated piping. The module follows a typical format that includes the following sections: (1) introduction, (2) module…

  6. Optically stimulated luminescence from quartz measured using the linear modulation technique

    DEFF Research Database (Denmark)

    Bulur, E.; Bøtter-Jensen, L.; Murray, A.S.

    2000-01-01

    The optically stimulated luminescence (OSL) from heated natural quartz has been investigated using the linear modulation technique (LMT), in which the excitation light intensity is increased linearly during stimulation. In contrast to conventional stimulation, which usually produces a monotonical...

  7. Evaluation of adaptation of ceramic inlays using optical coherence tomography and replica technique

    Directory of Open Access Journals (Sweden)

    TURK Ayse Gozde

    2018-02-01

    Full Text Available Abstract Optical coherence tomography (OCT has generally been used as a nondestructive technique to evaluate integrities of composite restorations. We investigated marginal and internal adaptations of ceramic inlay restorations with OCT and compared them to results with the silicone replica technique. Round-shaped class I cavities were prepared on 16 human maxillary first premolar teeth. Ceramic inlays were fabricated. Silicone replicas from inlays were obtained and sectioned to measure marginal and internal adaptations with a stereomicroscope (Leica Dfc 295, Bensheim, Germany. Inlays were cemented on respective teeth. Marginal and internal adaptations were then measured with the OCT system (Thorlabs, New Jersey, USA in 200- μm intervals. Replica and OCT measurements were compared with independent samples t-tests. A paired t-test was used to evaluate the marginal and internal adaptations of each group (p < 0.05. Marginal and internal adaptations were 100.97 ± 31.36 and 113.94 ± 39.75 μm, respectively, using the replica technique and 28.97 ± 17.86 and 97.87 ± 21.83 μm, respectively, using OCT. The differences between the techniques were significant (p = 0.00 and p = 0.01, respectively. On evaluation within the groups, internal adaptation values were found to be significantly higher than the marginal adaptation values for the replica technique (p = 0.00 and OCT (p = 0.00. Therefore, the replica and OCT techniques showed different results, with higher values of marginal and internal adaptation found with the replica technique. Marginal and internal adaptation values of ceramic inlays, whether measured by replica or OCT techniques, were within clinically acceptable limits.

  8. Evaluation of a software module for adaptive treatment planning and re-irradiation.

    Science.gov (United States)

    Richter, Anne; Weick, Stefan; Krieger, Thomas; Exner, Florian; Kellner, Sonja; Polat, Bülent; Flentje, Michael

    2017-12-28

    The aim of this work is to validate the Dynamic Planning Module in terms of usability and acceptance in the treatment planning workflow. The Dynamic Planning Module was used for decision making whether a plan adaptation was necessary within one course of radiation therapy. The Module was also used for patients scheduled for re-irradiation to estimate the dose in the pretreated region and calculate the accumulated dose to critical organs at risk. During one year, 370 patients were scheduled for plan adaptation or re-irradiation. All patient cases were classified according to their treated body region. For a sub-group of 20 patients treated with RT for lung cancer, the dosimetric effect of plan adaptation during the main treatment course was evaluated in detail. Changes in tumor volume, frequency of re-planning and the time interval between treatment start and plan adaptation were assessed. The Dynamic Planning Tool was used in 20% of treated patients per year for both approaches nearly equally (42% plan adaptation and 58% re-irradiation). Most cases were assessed for the thoracic body region (51%) followed by pelvis (21%) and head and neck cases (10%). The sub-group evaluation showed that unintended plan adaptation was performed in 38% of the scheduled cases. A median time span between first day of treatment and necessity of adaptation of 17 days (range 4-35 days) was observed. PTV changed by 12 ± 12% on average (maximum change 42%). PTV decreased in 18 of 20 cases due to tumor shrinkage and increased in 2 of 20 cases. Re-planning resulted in a reduction of the mean lung dose of the ipsilateral side in 15 of 20 cases. The experience of one year showed high acceptance of the Dynamic Planning Module in our department for both physicians and medical physicists. The re-planning can potentially reduce the accumulated dose to the organs at risk and ensure a better target volume coverage. In the re-irradiation situation, the Dynamic Planning Tool was used to

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

    International Nuclear Information System (INIS)

    Jani, S

    2014-01-01

    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

  10. Adapting Virtual Machine Techniques for Seamless Aspect Support

    NARCIS (Netherlands)

    Bockisch, Christoph; Arnold, Matthew; Dinkelaker, Tom; Mezini, Mira

    2006-01-01

    Current approaches to compiling aspect-oriented programs are inefficient. This inefficiency has negative effects on the productivity of the development process and is especially prohibitive for dynamic aspect deployment. In this work, we present how well-known virtual machine techniques can be used

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

    KAUST Repository

    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.

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

    KAUST Repository

    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.

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

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jakobsson, Andreas; Udesen, Jesper

    2007-01-01

    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......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...... 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 rig...

  14. Adaptive Landmark-Based Navigation System Using Learning Techniques

    DEFF Research Database (Denmark)

    Zeidan, Bassel; Dasgupta, Sakyasingha; Wörgötter, Florentin

    2014-01-01

    The goal-directed navigational ability of animals is an essential prerequisite for them to survive. They can learn to navigate to a distal goal in a complex environment. During this long-distance navigation, they exploit environmental features, like landmarks, to guide them towards their goal. In...... hexapod robots. As a result, it allows the robots to successfully learn to navigate to distal goals in complex environments.......The goal-directed navigational ability of animals is an essential prerequisite for them to survive. They can learn to navigate to a distal goal in a complex environment. During this long-distance navigation, they exploit environmental features, like landmarks, to guide them towards their goal....... 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...

  15. Application of Physiological Self-Regulation and Adaptive Task Allocation Techniques for Controlling Operator Hazardous States of Awareness

    Science.gov (United States)

    Prinzel, Lawrence J., III; Pope, Alan T.; Freeman, Frederick G.

    2001-01-01

    Prinzel, Hadley, Freeman, and Mikulka found that adaptive task allocation significantly enhanced performance only when used at the endpoints of the task workload continuum (i.e., very low or high workload), but that the technique degraded performance if invoked during other levels of task demand. These researchers suggested that other techniques should be used in conjunction with adaptive automation to help minimize the onset of hazardous states of awareness (HSA) and keep the operator 'in-the-loop.' The paper reports on such a technique that uses psychophysiological self-regulation to modulate the level of task engagement. Eighteen participants were assigned to three groups (self-regulation, false feedback, and control) and performed a compensatory tracking task that was cycled between three levels of task difficulty on the basis of the electroencephalogram (EEG) record. Those participants who had received self-regulation training performed significantly better and reported lower NASA-TLX scores than participants in the false feedback and control groups. Furthermore, the false feedback and control groups had significantly more task allocations resulting in return-to-manual performance decrements and higher EEG difference scores. Theoretical and practical implications of these results for adaptive automation are discussed.

  16. Swarm Intelligence: New Techniques for Adaptive Systems to Provide Learning Support

    Science.gov (United States)

    Wong, Lung-Hsiang; Looi, Chee-Kit

    2012-01-01

    The notion of a system adapting itself to provide support for learning has always been an important issue of research for technology-enabled learning. One approach to provide adaptivity is to use social navigation approaches and techniques which involve analysing data of what was previously selected by a cluster of users or what worked for…

  17. Adaptive Modulation Approach for Robust MPEG-4 AAC Encoded Audio Transmission

    Science.gov (United States)

    2011-11-01

    Codec (AAC) - Main profile with the single channel element (SCE) syntax, and transmit it using the audio data transport stream (ADTS) format. Single...4 AAC ENCODED AUDIO TRANSMISSION 5a. CONTRACT NUMBER IN HOUSE 5b. GRANT NUMBER FA8750-11-1-0048 5c. PROGRAM ELEMENT NUMBER 62702F 6. AUTHOR(S... audio data over fading wireless channels using Unequal Error Protection based on adaptive modulation and forward error correcting (FEC) codes. The

  18. A novel wireless modulation technique for inter-standard communications

    NARCIS (Netherlands)

    Bekkaoui, A.; Haartsen, J.C.

    2006-01-01

    A new technique is presented with permits transceivers of different radio standards to communicate with each other. Applications are found in unlicensed bands where radios using different technologies, like for example Bluetooth, ZigBee, or WLAN IEEE 802.11, have to share the same radio spectrum. If

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

    NARCIS (Netherlands)

    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

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

    Science.gov (United States)

    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.

  1. Parallel adaptive mesh refinement techniques for plasticity problems

    Energy Technology Data Exchange (ETDEWEB)

    Barry, W.J. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Civil and Environmental Engineering; Jones, M.T. [Virginia Polytechnic Institute, Blacksburg, VA (United States). Dept. of Electrical and Computer Engineering]|[State Univ., Blacksburg, VA (United States); Plassmann, P.E. [Argonne National Lab., IL (United States)

    1997-12-31

    The accurate modeling of the nonlinear properties of materials can be computationally expensive. Parallel computing offers an attractive way for solving such problems; however, the efficient use of these systems requires the vertical integration of a number of very different software components, we explore the solution of two- and three-dimensional, small-strain plasticity problems. We consider a finite-element formulation of the problem with adaptive refinement of an unstructured mesh to accurately model plastic transition zones. We present a framework for the parallel implementation of such complex algorithms. This framework, using libraries from the SUMAA3d project, allows a user to build a parallel finite-element application without writing any parallel code. To demonstrate the effectiveness of this approach on widely varying parallel architectures, we present experimental results from an IBM SP parallel computer and an ATM-connected network of Sun UltraSparc workstations. The results detail the parallel performance of the computational phases of the application during the process while the material is incrementally loaded.

  2. Parallel adaptive mesh refinement techniques for plasticity problems

    Science.gov (United States)

    Barry, W. J.; Jones, M. T.; Plassmann, P. E.

    1997-01-01

    The accurate modeling of the nonlinear properties of materials can be computationally expensive. Parallel computing offers an attractive way for solving such problems; however, the efficient use of these systems requires the vertical integration of a number of very different software components, we explore the solution of two- and three-dimensional, small-strain plasticity problems. We consider a finite-element formulation of the problem with adaptive refinement of an unstructured mesh to accurately model plastic transition zones. We present a framework for the parallel implementation of such complex algorithms. This framework, using libraries from the SUMAA3d project, allows a user to build a parallel finite-element application without writing any parallel code. To demonstrate the effectiveness of this approach on widely varying parallel architectures, we present experimental results from an IBM SP parallel computer and an ATM-connected network of Sun UltraSparc workstations. The results detail the parallel performance of the computational phases of the application during the process while the material is incrementally loaded.

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

    Science.gov (United States)

    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.

  4. Ripples in Communication : Reconfigurable and Adaptive Wireless Communication Systems based on Wavelet Packet Modulators

    NARCIS (Netherlands)

    Lakshmanan, M.K.

    2011-01-01

    Wavelet Packet Modulation (WPM) is a multi-carrier transmission technique that uses orthogonal wavelet packet bases to combine a collection of information bits into a single composite signal. This system can be considered as a viable alternative, for wide-band communication, to the popular

  5. Adaptation Mechanism of the Aspartate Receptor: Electrostatics of the Adaptation Subdomain Play a Key Role in Modulating Kinase Activity†

    Science.gov (United States)

    Starrett, Diane J.; Falke, Joseph J.

    2010-01-01

    The aspartate receptor of the Escherichia coli and Salmonella typhimurium chemotaxis pathway generates a transmembrane signal that regulates the activity of the cytoplasmic kinase CheA. Previous studies have identified a region of the cytoplasmic domain that is critical to receptor adaptation and kinase regulation. This region, termed the adaptation subdomain, contains a high density of acidic residues, including specific glutamate residues that serve as receptor adaptation sites. However, the mechanism of signal propagation through this region remains poorly understood. This study uses site-directed mutagenesis to neutralize each acidic residue within the subdomain to probe the hypothesis that electrostatics in this region play a significant role in the mechanism of kinase activation and modulation. Each point mutant was tested for its ability to regulate chemotaxis in vivo and kinase activity in vitro. Four point mutants (D273N, E281Q, D288N, and E477Q) were found to superactivate the kinase relative to the wild-type receptor, and all four of these kinase-activating substitutions are located along the same intersubunit interface as the adaptation sites. These activating substitutions retained the wild-type ability of the attractant-occupied receptor to inhibit kinase activity. When combined in a quadruple mutant (D273N/E281Q/D288N/E477Q), the four charge-neutralizing substitutions locked the receptor in a kinase-superactivating state that could not be fully inactivated by the attractant. Similar lock-on character was observed for a charge reversal substitution, D273R. Together, these results implicate the electrostatic interactions at the intersubunit interface as a major player in signal transduction and kinase regulation. The negative charge in this region destabilizes the local structure in a way that enhances conformational dynamics, as detected by disulfide trapping, and this effect is reversed by charge neutralization of the adaptation sites. Finally, two

  6. Cross-section adjustment techniques for BWR adaptive simulation

    Science.gov (United States)

    Jessee, Matthew Anderson

    Computational capability has been developed to adjust multi-group neutron cross-sections to improve the fidelity of boiling water reactor (BWR) modeling and simulation. The method involves propagating multi-group neutron cross-section uncertainties through BWR computational models to evaluate uncertainties in key core attributes such as core k-effective, nodal power distributions, thermal margins, and in-core detector readings. Uncertainty-based inverse theory methods are then employed to adjust multi-group cross-sections to minimize the disagreement between BWR modeling predictions and measured plant data. For this work, measured plant data were virtually simulated in the form of perturbed 3-D nodal power distributions with discrepancies with predictions of the same order of magnitude as expected from plant data. Using the simulated plant data, multi-group cross-section adjustment reduces the error in core k-effective to less than 0.2% and the RMS error in nodal power to 4% (i.e. the noise level of the in-core instrumentation). To ensure that the adapted BWR model predictions are robust, Tikhonov regularization is utilized to control the magnitude of the cross-section adjustment. In contrast to few-group cross-section adjustment, which was the focus of previous research on BWR adaptive simulation, multigroup cross-section adjustment allows for future fuel cycle design optimization to include the determination of optimal fresh fuel assembly designs using the adjusted multi-group cross-sections. The major focus of this work is to efficiently propagate multi-group neutron cross-section uncertainty through BWR lattice physics calculations. Basic neutron cross-section uncertainties are provided in the form of multi-group cross-section covariance matrices. For energy groups in the resolved resonance energy range, the cross-section uncertainties are computed using an infinitely-dilute approximation of the neutron flux. In order to accurately account for spatial and

  7. Measurement of the amplitude and phase transfer functions of an optical modulator using a heterodyne technique

    DEFF Research Database (Denmark)

    Romstad, Francis Pascal; Birkedal, Dan; Mørk, Jesper

    2001-01-01

    We present a new technique that measures the full amplitude and phase transfer curves of the modulator as a function of the applied bias, from which the small signal α-parameter can be calculated. The technique measures the amplitude and phase transfer functions simultaneously and directly...

  8. Evaluation of adaptation of ceramic inlays using optical coherence tomography and replica technique.

    Science.gov (United States)

    Ayse Gozde, Turk; Metin, Sabuncu; Mubin, Ulusoy

    2018-02-01

    Optical coherence tomography (OCT) has generally been used as a nondestructive technique to evaluate integrities of composite restorations. We investigated marginal and internal adaptations of ceramic inlay restorations with OCT and compared them to results with the silicone replica technique. Round-shaped class I cavities were prepared on 16 human maxillary first premolar teeth. Ceramic inlays were fabricated. Silicone replicas from inlays were obtained and sectioned to measure marginal and internal adaptations with a stereomicroscope (Leica Dfc 295, Bensheim, Germany). Inlays were cemented on respective teeth. Marginal and internal adaptations were then measured with the OCT system (Thorlabs, New Jersey, USA) in 200- μm intervals. Replica and OCT measurements were compared with independent samples t-tests. A paired t-test was used to evaluate the marginal and internal adaptations of each group (p inlays, whether measured by replica or OCT techniques, were within clinically acceptable limits.

  9. My Solar System: A Developmentally Adapted Eco-Mapping Technique for Children

    Science.gov (United States)

    Curry, Jennifer R.; Fazio-Griffith, Laura J.; Rohr, Shannon N.

    2008-01-01

    Counseling children requires specific skills and techniques, such as play therapy and expressive arts, to address developmental manifestations and to facilitate the understanding of presenting problems. This article outlines an adapted eco-mapping activity that can be used as a creative counseling technique with children in order to promote…

  10. The Adaptive Edge: Introducing Adaptive Skills Techniques to Army Special Forces

    Science.gov (United States)

    2010-12-01

    22 4. Relaxation The fourth mental technique is relaxation. According to Brian Mac, who is a Sports Coach to athletes in the United Kingdom, the...or that.”58 As mentioned previously, these five techniques just outlined are those most frequently used by many athletes and coaches in a variety...Bill: You know we definitely all do this. I used it on my recent trip to Colombia . My detachment and I had gone down to conduct a JCET

  11. Radio over fiber link with adaptive order n‐QAM optical phase modulated OFDM and digital coherent detection

    DEFF Research Database (Denmark)

    Arlunno, Valeria; Borkowski, Robert; Guerrero Gonzalez, Neil

    2011-01-01

    Successful digital coherent demodulation of asynchronous optical phase‐modulated adaptive order QAM (4, 16, and 64) orthogonal frequency division multiplexing signals is achieved by a single reconfigurable digital receiver after 78 km of optical deployed fiber transmission....

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  13. Adaptive Countering Technique for Angle Deception Based on Dual Polarization Radar Seeker

    Directory of Open Access Journals (Sweden)

    Qiang Zhang

    2017-01-01

    Full Text Available Angle deception jamming makes the monopulse radar seeker track to itself but not the real target, which is catastrophic for the guidance radar. In this paper, an adaptive technique based on dual polarization radar is presented to counter it. How angle deception jamming acts on the monopulse tracking radar is first investigated. An angle estimation technique of the real target is then derived from the conventional monopulse method, although it is being interfered with by angle deception jamming. Meanwhile, the polarization ratio characteristic of the angle deception jamming could be adaptively estimated in current practical scene. Furthermore, the similar characteristic of Jones vectors is defined as the rule to judge whether the target is being interfered with by jamming. It can make the radar seeker select different techniques for angle estimation adaptively. Finally, two major factors of angle estimation accuracy are analyzed by simulation and the effectiveness of the proposed technique is proved through experiments.

  14. [Lumbar post-laminectomy syndrome: II. Pain management using neuro-modulation techniques].

    Science.gov (United States)

    Robaina Padrón, F J

    2008-02-01

    The application of neuro-modulation techniques in general is currently gaining acceptance in various aspects of medicine. Neuro-modulation is defined as: "Therapeutical interventions using implantable devices to modify the functioning of central, peripheral and autonomic nervous systems". Following lumbar disc surgery, or lumbar spine surgery in general, several chronic pain syndromes can result, either in the lumbar region and/or in the lower limbs. The current status is for the application of surgery to the degenerative spine (degenerative disc disease and lumbar stenosis) for the relief of chronic pain. A review of the methodology of evidence based medicine, show that the instrumented and fusion techniques are not the answered despite 20 years of the use of these techniques following failure of surgery for the relief of back pain syndrome. Neuro-modulation techniques represent a step in the right direction for the management of these chronic pain syndromes. Frequently they enable the resolution of chronic pain following spine surgery without having to resort to repeat surgery. We describe here the different neuro-modulation techniques (spinal cord stimulation, spinal drug infusions) which can be used in the case of back surgery failure, and we describe technical aspects and "tricks of the trade" for the correct implantation of the devices used in techniques. Neuro-modulation techniques are applied to the management of chronic pain following disc surgery and represent a valid alternative to repeat surgery and/or arthrodesis (instrumented or not). Neurosurgeons are again called to play active roles in the field of neuro-modulation for the treatment.

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

    KAUST Repository

    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.

  16. APPLIED DIAGNOSTIC MODULE FOR DETERMINING COGNITIVE MODEL PARAMETERS OF SUBJECTS OF EDUCATION IN AN ADAPTIVE ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Anatoly N. Vetrov

    2017-01-01

    Full Text Available Abstract. Objectives To increase the functional efficiency of information and educational environments created by automated training systems by realising individually oriented formation of knowledge using adaptive generation of heterogeneous educational influences based on an innovative block of parametric cognitive models and a set of programs to support the automation of research tasks. Method System analysis and modeling of the information and educational environment. In the process of automating the diagnosis of the individual personality characteristics of the subject of education, each method of investigation determines the input: localisation of research method, name of block of questions (subtest, textual explanatory content, formulation of question and answer variants, nominal value of the time interval for displaying the formulation of the question, as well as the graphical accompaniment of a specific question and answers thereto. Results The applied diagnostic module acts as a component of the automated learning system with adaptation properties on the basis of the innovative block of parametric cognitive models. The training system implements the generation of an ordered sequence of informational and educational influences that reflect the content of the subject of a study. Conclusion The applied diagnostic module is designed to automate the study of physiological, psychological and linguistic parameters of the cognitive model of the subject of education to provide a systematic analysis of the information and educational environment and the realisation of adaptive generation of educational influences by using training automation approaches that allow the individual characteristics of trainees to be taken into account. 

  17. Field-In-Field Technique With Intrafractionally Modulated Junction Shifts for Craniospinal Irradiation

    International Nuclear Information System (INIS)

    Yom, Sue S.; Frija, Erik K. C.; Mahajan, Anita; Chang, Eric; Klein, Kelli C.; Shiu, Almon; Ohrt, Jared; Woo, Shiao

    2007-01-01

    Purpose: To plan craniospinal irradiation with 'field-in-field' (FIF) homogenization in combination with daily, intrafractional modulation of the field junctions, to minimize the possibility of spinal cord overdose. Methods and Materials: Lateral cranial fields and posterior spinal fields were planned using a forward-planned, step-and-shoot FIF technique. Field junctions were automatically modulated and custom-weighted for maximal homogeneity within each treatment fraction. Dose-volume histogram analyses and film dosimetry were used to assess results. Results: Plan inhomogeneity improved with FIF. Planning with daily modulated junction shifts provided consistent dose delivery during each fraction of treatment across the junctions. Modulation minimized the impact of a 5-mm setup error at the junction. Film dosimetry confirmed that no point in the junction exceeded the anticipated dose. Conclusions: Field-in-field planning and modulated junction shifts improve the homogeneity and consistency of daily dose delivery, simplify treatment, and reduce the impact of setup errors

  18. Noise reduction techniques used on the high power klystron modulators at Argonne National Laboratory

    International Nuclear Information System (INIS)

    Russell, T.J.

    1993-01-01

    The modulators used in the Advanced Photon Source at Argonne National Laboratory have been redesigned with an emphasis on electrical noise reduction. Since the modulators are 100 MW modulators with <700 ns rise time, electrical noise can be coupled very easily to other electronic equipment in the area. This paper will detail the efforts made to reduce noise coupled to surrounding equipment. Shielding and sound grounding techniques accomplished the goal of drastically reducing the noise induced in surrounding equipment. The approach used in grounding and shielding will be discussed, and data will be presented comparing earlier designs to the improved design

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

    DEFF Research Database (Denmark)

    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 between...... 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...

  20. Endothelial nitric oxide synthase polymorphisms and adaptation of parasympathetic modulation to exercise training.

    Science.gov (United States)

    Silva, Bruno M; Neves, Fabricia J; Negrão, Marcelo V; Alves, Cleber R; Dias, Rodrigo G; Alves, Guilherme B; Pereira, Alexandre C; Rondon, Maria U; Krieger, José E; Negrão, Carlos E; DA Nóbrega, Antonio Claudio Lucas

    2011-09-01

    There is a large interindividual variation in the parasympathetic adaptation induced by aerobic exercise training, which may be partially attributed to genetic polymorphisms. Therefore, we investigated the association among three polymorphisms in the endothelial nitric oxide gene (-786T>C, 4b4a, and 894G>T), analyzed individually and as haplotypes, and the parasympathetic adaptation induced by exercise training. Eighty healthy males, age 20-35 yr, were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis, and haplotypes were inferred using the software PHASE 2.1. Autonomic modulation (i.e., HR variability and spontaneous baroreflex sensitivity) and peak oxygen consumption (VO(2peak)) were measured before and after training (running, moderate to severe intensity, three times per week, 60 min·day(-1), during 18 wk). Training increased VO(2peak) (P baroreflex sensitivity after training (change: wild type (-786TT) = 2% ± 89% vs polymorphic (-786TC/CC) = -28% ± 60%, median ± quartile range, P = 0.03), and parasympathetic modulation was marginally reduced in subjects with the 894T polymorphic allele (change: wild type (894GG) = 8% ± 67% vs polymorphic (894GT/TT) = -18% ± 59%, median ± quartile range, P = 0.06). Furthermore, parasympathetic modulation percent change was different between the haplotypes containing wild-type alleles (-786T/4b/894G) and polymorphic alleles at positions -786 and 894 (-786C/4b/894T) (-6% ± 56% vs -41% ± 50%, median ± quartile range, P = 0.04). The polymorphic allele at position -786 and the haplotype containing polymorphic alleles at positions -786 and 894 in the endothelial nitric oxide gene were associated with decreased parasympathetic modulation after exercise training.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    International Nuclear Information System (INIS)

    Ito, Kei; Ohshima, Hiroyuki; Kunugi, Tomoaki

    2010-01-01

    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)

  3. Development of the MCM-D technique for pixel detector modules

    International Nuclear Information System (INIS)

    Grah, C.

    2005-03-01

    This thesis treats a copper--polymer based thin film technology, the MCM-D technique and its application when building hybrid pixel detector modules. The ATLAS experiment at the LHC will be equipped with a pixel detector system. The basic mechanical units of the pixel detector are multi chip modules. The main components of these modules are: 16 electronic chips, a controller chip and a large sensor tile, featuring more than 46000 sensor cells. MCM-D is a superior technique to build the necessary signal bus system and the power distribution system directly on the active sensor tile. In collaboration with the Fraunhofer Institute for Reliability and Microintegration, IZM, the thin film process is reviewed and enhanced. The multi layer system was designed and optimized for the interconnection system as well as for the 46000 pixel contacts. Laboratory measurements on prototypes prove that complex routing schemes for geometrically optimized single chips are suitable and have negligible influence on the front--end chips performance. A full scale MCM-D module has been built and it is shown that the technology is suitable to build pixel detector modules. Further tests include the investigation of the impact of hadronic irradiation on the thin film layers. Single chip assemblies have been operated in a test beam environment and the feasibility of the optimization of the sensors could be shown. A review on the potential as well as the perspective for the MCM-D technique in future experiments is given

  4. [The Hungarian adaptation of Anxiety disorder module in the SCID-I/NP research version].

    Science.gov (United States)

    Gerevich, József; Bácskai, Erika; Matuszka, Balázs; Czobor, Pál

    2010-01-01

    The SCID-I structured clinical interview based on the DSM-IV-TR criteria is widely used in internationally, but the reliability and validity of its Hungarian version has not been investigated. This paper presents the results of the first validity and reliability study of the Hungarian version of the SCID-I/NP's (Structured Clinical Interview for DSM-IV-TR Axis I Disorders Non-patient Edition) Anxiety Disorders module. The language adaptation of the diagnostic interview and of the user's guide was conducted in accordance with the WHO recommendations. SCID-I/NP Overview and Screening module; SCID-I/NP Module F: Anxiety Disorders; Tests providing external validity: Beck Anxiety Inventory (BAI), Adult ADHD Self-Report Scale (ASRS), Buss-Perry Aggression Questionnaire (AQ), Alcohol Use Disorders Identification Test (AUDIT). The study sample consisted of 741 patients attended at three GP's offices. The trial's duration was two months. GLM analysis, Chi-square test, Fisher's exact test, Kappa and weighted Kappa statistics. Results showed a significant interrater-agreement between the rater pairs. For screening modules yealding negative results, the false-negative analysis indicated a subthreshold positive diagnosis in one case. External validity analyses showed significant discrepancies in terms of gender, marital status and past psychiatric treatments among the three sample groups including those with diagnosis present, subthreshold diagnosis, diagnosis absent. In terms of the psychometric scales, we found significant differences on the BAI and the ASRS in these groups. In the case of AQ we found significant differences in total score and in the factors of hostility and anger: the diagnosis present group showed significantly elevated severity values compared to the other two groups. The Anxiety Disorders Module of the SCID-I/NP is suitable for detecting anxiety disorders in non-psychiatric population, and hence enables the early admission for treatment.

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

    Science.gov (United States)

    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).

  6. Advanced Intensity-Modulation Continuous-Wave Lidar Techniques for ASCENDS O2 Column Measurements

    Science.gov (United States)

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

    2015-01-01

    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.

  7. Substance P Differentially Modulates Firing Rate of Solitary Complex (SC) Neurons from Control and Chronic Hypoxia-Adapted Adult Rats

    Science.gov (United States)

    Nichols, Nicole L.; Powell, Frank L.; Dean, Jay B.; Putnam, Robert W.

    2014-01-01

    NK1 receptors, which bind substance P, are present in the majority of brainstem regions that contain CO2/H+-sensitive neurons that play a role in central chemosensitivity. However, the effect of substance P on the chemosensitive response of neurons from these regions has not been studied. Hypoxia increases substance P release from peripheral afferents that terminate in the caudal nucleus tractus solitarius (NTS). Here we studied the effect of substance P on the chemosensitive responses of solitary complex (SC: NTS and dorsal motor nucleus) neurons from control and chronic hypoxia-adapted (CHx) adult rats. We simultaneously measured intracellular pH and electrical responses to hypercapnic acidosis in SC neurons from control and CHx adult rats using the blind whole cell patch clamp technique and fluorescence imaging microscopy. Substance P significantly increased the basal firing rate in SC neurons from control and CHx rats, although the increase was smaller in CHx rats. However, substance P did not affect the chemosensitive response of SC neurons from either group of rats. In conclusion, we found that substance P plays a role in modulating the basal firing rate of SC neurons but the magnitude of the effect is smaller for SC neurons from CHx adult rats, implying that NK1 receptors may be down regulated in CHx adult rats. Substance P does not appear to play a role in modulating the firing rate response to hypercapnic acidosis of SC neurons from either control or CHx adult rats. PMID:24516602

  8. Substance P differentially modulates firing rate of solitary complex (SC neurons from control and chronic hypoxia-adapted adult rats.

    Directory of Open Access Journals (Sweden)

    Nicole L Nichols

    Full Text Available NK1 receptors, which bind substance P, are present in the majority of brainstem regions that contain CO2/H(+-sensitive neurons that play a role in central chemosensitivity. However, the effect of substance P on the chemosensitive response of neurons from these regions has not been studied. Hypoxia increases substance P release from peripheral afferents that terminate in the caudal nucleus tractus solitarius (NTS. Here we studied the effect of substance P on the chemosensitive responses of solitary complex (SC: NTS and dorsal motor nucleus neurons from control and chronic hypoxia-adapted (CHx adult rats. We simultaneously measured intracellular pH and electrical responses to hypercapnic acidosis in SC neurons from control and CHx adult rats using the blind whole cell patch clamp technique and fluorescence imaging microscopy. Substance P significantly increased the basal firing rate in SC neurons from control and CHx rats, although the increase was smaller in CHx rats. However, substance P did not affect the chemosensitive response of SC neurons from either group of rats. In conclusion, we found that substance P plays a role in modulating the basal firing rate of SC neurons but the magnitude of the effect is smaller for SC neurons from CHx adult rats, implying that NK1 receptors may be down regulated in CHx adult rats. Substance P does not appear to play a role in modulating the firing rate response to hypercapnic acidosis of SC neurons from either control or CHx adult rats.

  9. Dopamine Modulates Adaptive Prediction Error Coding in the Human Midbrain and Striatum.

    Science.gov (United States)

    Diederen, Kelly M J; Ziauddeen, Hisham; Vestergaard, Martin D; Spencer, Tom; Schultz, Wolfram; Fletcher, Paul C

    2017-02-15

    are modulated by the brain chemical dopamine are sensitive to reward variability. Here, we aimed to directly relate dopamine to learning about variable rewards, and the neural encoding of associated teaching signals. We perturbed dopamine in healthy individuals using dopaminergic medication and asked them to predict variable rewards while we made brain scans. Dopamine perturbations impaired learning and the neural encoding of reward variability, thus establishing a direct link between dopamine and adaptation to reward variability. These results aid our understanding of clinical conditions associated with dopaminergic dysfunction, such as psychosis. Copyright © 2017 Diederen et al.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. Adaptive finite element techniques for the Maxwell equations using implicit a posteriori error estimates

    NARCIS (Netherlands)

    Harutyunyan, D.; Izsak, F.; van der Vegt, Jacobus J.W.; Bochev, Mikhail A.

    For the adaptive solution of the Maxwell equations on three-dimensional domains with N´ed´elec edge finite element methods, we consider an implicit a posteriori error estimation technique. On each element of the tessellation an equation for the error is formulated and solved with a properly chosen

  12. RF Sub-sampling Receiver Architecture based on Milieu Adapting Techniques

    DEFF Research Database (Denmark)

    Behjou, Nastaran; Larsen, Torben; Jensen, Ole Kiel

    2012-01-01

    A novel sub-sampling based architecture is proposed which has the ability of reducing the problem of image distortion and improving the signal to noise ratio significantly. The technique is based on sensing the environment and adapting the sampling rate of the receiver to the best possible...

  13. Voice Therapy Techniques Adapted to Treatment of Habit Cough: A Pilot Study.

    Science.gov (United States)

    Blager, Florence B.; And Others

    1988-01-01

    Individuals with long-standing habit cough having no organic basis can be successfully treated with a combination of psychotherapy and speech therapy. Techniques for speech therapy are adapted from those used with hyperfunctional voice disorders to fit this debilitating laryngeal disorder. (Author)

  14. Application of adaptive antenna techniques to future commercial satellite communications. Executive summary

    Science.gov (United States)

    Ersoy, L.; Lee, E. A.; Matthews, E. W.

    1987-01-01

    The purpose of this contract was to identify the application of adaptive antenna technique in future operational commercial satellite communication systems and to quantify potential benefits. The contract consisted of two major subtasks. Task 1, Assessment of Future Commercial Satellite System Requirements, was generally referred to as the Adaptive section. Task 2 dealt with Pointing Error Compensation Study for a Multiple Scanning/Fixed Spot Beam Reflector Antenna System and was referred to as the reconfigurable system. Each of these tasks was further subdivided into smaller subtasks. It should also be noted that the reconfigurable system is usually defined as an open-loop system while the adaptive system is a closed-loop system. The differences between the open- and closed-loop systems were defined. Both the adaptive and reconfigurable systems were explained and the potential applications of such systems were presented in the context of commercial communication satellite systems.

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

    Science.gov (United States)

    Castellini, P.; Cecchini, S.; Stroppa, L.; Paone, N.

    2013-05-01

    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.

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

    International Nuclear Information System (INIS)

    Castellini, P; Cecchini, S; Stroppa, L; Paone, N

    2013-01-01

    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)

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

    Directory of Open Access Journals (Sweden)

    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.

  18. Design of near-perfect-reconstructed transmultiplexer using different modulation techniques: A comparative study

    Directory of Open Access Journals (Sweden)

    A. Vishwakarma

    2017-07-01

    Full Text Available In this paper, an efficient iterative method for design of near-perfect reconstructed transmultiplexer (NPR TMUX is proposed for the prescribed roll-off factor (RF and stop band attenuation (As. In this method, windowing technique has been used for the design of prototype filter, and different modulation techniques have been exploited for designing multi-channel transmultiplexer (TMUX. In this method, inter-channel interference (ICI is iteratively minimized so that it approximately reduces to ideal value zero. Design example is given to illustrate the superiority of the proposed method over earlier reported work. A comparative study of the performance of different modulation techniques for designing TMUX is also presented.

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

    Science.gov (United States)

    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.

  20. Analysis technique for controlling system wavefront error with active/adaptive optics

    Science.gov (United States)

    Genberg, Victor L.; Michels, Gregory J.

    2017-08-01

    The ultimate goal of an active mirror system is to control system level wavefront error (WFE). In the past, the use of this technique was limited by the difficulty of obtaining a linear optics model. In this paper, an automated method for controlling system level WFE using a linear optics model is presented. An error estimate is included in the analysis output for both surface error disturbance fitting and actuator influence function fitting. To control adaptive optics, the technique has been extended to write system WFE in state space matrix form. The technique is demonstrated by example with SigFit, a commercially available tool integrating mechanical analysis with optical analysis.

  1. An open-loop RFOG based on harmonic division technique to suppress LD's intensity modulation noise

    Science.gov (United States)

    Ying, Diqing; Wang, Zeyu; Mao, Jianmin; Jin, Zhonghe

    2016-11-01

    A harmonic division technique is proposed for an open-loop resonator fiber optic gyro (RFOG) to suppress semiconductor laser diode's (LD's) intensity modulation noise. The theoretical study indicates the RFOG with this technique is immune to the intensity noise. The simulation and experimental results show this technique would lead to a diminished linear region, which still could be acceptable for an RFOG applied to low rotation rate detection. The tests for the gyro output signal are carried out with/without noise suppressing methods, including the harmonic division technique and previously proposed signal compensation technique. With the harmonic division technique at the rotation rate of 10 deg/s, the stability of gyro output signal is improved from 1.07 deg/s to 0.0361 deg/s, whose noise suppressing ratio is more than 3 times as that of the signal compensation technique. And especially, a 3.12 deg/s signal jump is significantly removed with the harmonic division technique; in contrast, a residual 0.36 deg/s signal jump still exists with the signal compensation technique. It is concluded the harmonic division technique does work in intensity noise suppressing under dynamic condition, and it is superior to the signal compensation technique.

  2. Endogenous adaptation to low oxygen modulates T-cell regulatory pathways in EAE.

    Science.gov (United States)

    Esen, Nilufer; Katyshev, Vladimir; Serkin, Zakhar; Katysheva, Svetlana; Dore-Duffy, Paula

    2016-01-19

    In the brain, chronic inflammatory activity may lead to compromised delivery of oxygen and glucose suggesting that therapeutic approaches aimed at restoring metabolic balance may be useful. In vivo exposure to chronic mild normobaric hypoxia (10 % oxygen) leads to a number of endogenous adaptations that includes vascular remodeling (angioplasticity). Angioplasticity promotes tissue survival. We have previously shown that induction of adaptive angioplasticity modulates the disease pattern in myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE). In the present study, we define mechanisms by which adaptation to low oxygen functionally ameliorates the signs and symptoms of EAE and for the first time show that tissue hypoxia may fundamentally alter neurodegenerative disease. C57BL/6 mice were immunized with MOG, and some of them were kept in the hypoxia chambers (day 0) and exposed to 10 % oxygen for 3 weeks, while the others were kept at normoxic environment. Sham-immunized controls were included in both hypoxic and normoxic groups. Animals were sacrificed at pre-clinical and peak disease periods for tissue collection and analysis. Exposure to mild hypoxia decreased histological evidence of inflammation. Decreased numbers of cluster of differentiation (CD)4+ T cells were found in the hypoxic spinal cords associated with a delayed Th17-specific cytokine response. Hypoxia-induced changes did not alter the sensitization of peripheral T cells to the MOG peptide. Exposure to mild hypoxia induced significant increases in anti-inflammatory IL-10 levels and an increase in the number of spinal cord CD25+FoxP3+ T-regulatory cells. Acclimatization to mild hypoxia incites a number of endogenous adaptations that induces an anti-inflammatory milieu. Further understanding of these mechanisms system may pinpoint possible new therapeutic targets to treat neurodegenerative disease.

  3. An adaptive dual-optimal path-planning technique for unmanned air vehicles

    Directory of Open Access Journals (Sweden)

    Whitfield Clifford A.

    2016-01-01

    Full Text Available A multi-objective technique for unmanned air vehicle path-planning generation through task allocation has been developed. The dual-optimal path-planning technique generates real-time adaptive flight paths based on available flight windows and environmental influenced objectives. The environmentally-influenced flight condition determines the aircraft optimal orientation within a downstream virtual window of possible vehicle destinations that is based on the vehicle’s kinematics. The intermittent results are then pursued by a dynamic optimization technique to determine the flight path. This path-planning technique is a multi-objective optimization procedure consisting of two goals that do not require additional information to combine the conflicting objectives into a single-objective. The technique was applied to solar-regenerative high altitude long endurance flight which can benefit significantly from an adaptive real-time path-planning technique. The objectives were to determine the minimum power required flight paths while maintaining maximum solar power for continual surveillance over an area of interest (AOI. The simulated path generation technique prolonged the flight duration over a sustained turn loiter flight path by approximately 2 months for a year of flight. The potential for prolonged solar powered flight was consistent for all latitude locations, including 2 months of available flight at 60° latitude, where sustained turn flight was no longer capable.

  4. A Novel Adaptive Modulation Based on Nondata-Aided Error Vector Magnitude in Non-Line-Of-Sight Condition of Wireless Sensor Network.

    Science.gov (United States)

    Yang, Fan; Zeng, Xiaoping; Mao, Haiwei; Jian, Xin; Tan, Xiaoheng; Du, Derong

    2018-01-15

    The high demand for multimedia applications in environmental monitoring, invasion detection, and disaster aid has led to the rise of wireless sensor network (WSN). With the increase of reliability and diversity of information streams, the higher requirements on throughput and quality of service (QoS) have been put forward in data transmission between two sensor nodes. However, lower spectral efficiency becomes a bottleneck in non-line-of-sight (NLOS) transmission of WSN. This paper proposes a novel nondata-aided error vector magnitude based adaptive modulation (NDA-EVM-AM) to solve the problem. NDA-EVM is considered as a new metric to evaluate the quality of NLOS link for adaptive modulation in WSN. By modeling the NLOS scenario as the η - μ fading channel, a closed-form expression for the NDA-EVM of multilevel quadrature amplitude modulation (MQAM) signals over the η - μ fading channel is derived, and the relationship between SER and NDA-EVM is also formulated. Based on these results, NDA-EVM state machine is designed for adaptation strategy. The algorithmic complexity of NDA-EVM-AM is analyzed and the outage capacity of NDA-EVM-AM in an NLOS scenario is also given. The performances of NDA-EVM-AM are compared by simulation, and the results show that NDA-EVM-AM is an effective technique to be used in the NLOS scenarios of WSN. This technique can accurately reflect the channel variations and efficiently adjust modulation order to better match the channel conditions, hence, obtaining better performance in average spectral efficiency.

  5. Adaptive subdomain modeling: A multi-analysis technique for ocean circulation models

    Science.gov (United States)

    Altuntas, Alper; Baugh, John

    2017-07-01

    Many coastal and ocean processes of interest operate over large temporal and geographical scales and require a substantial amount of computational resources, particularly when engineering design and failure scenarios are also considered. This study presents an adaptive multi-analysis technique that improves the efficiency of these computations when multiple alternatives are being simulated. The technique, called adaptive subdomain modeling, concurrently analyzes any number of child domains, with each instance corresponding to a unique design or failure scenario, in addition to a full-scale parent domain providing the boundary conditions for its children. To contain the altered hydrodynamics originating from the modifications, the spatial extent of each child domain is adaptively adjusted during runtime depending on the response of the model. The technique is incorporated in ADCIRC++, a re-implementation of the popular ADCIRC ocean circulation model with an updated software architecture designed to facilitate this adaptive behavior and to utilize concurrent executions of multiple domains. The results of our case studies confirm that the method substantially reduces computational effort while maintaining accuracy.

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

    Science.gov (United States)

    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.

  7. Tunable modulation of refracted lamb wave front facilitated by adaptive elastic metasurfaces

    Science.gov (United States)

    Li, Shilong; Xu, Jiawen; Tang, J.

    2018-01-01

    This letter reports designs of adaptive metasurfaces capable of modulating incoming wave fronts of elastic waves through electromechanical-tuning of their cells. The proposed elastic metasurfaces are composed of arrayed piezoelectric units with individually connected negative capacitance elements that are online tunable. By adjusting the negative capacitances properly, accurately formed, discontinuous phase profiles along the elastic metasurfaces can be achieved. Subsequently, anomalous refraction with various angles can be realized on the transmitted lowest asymmetric mode Lamb wave. Moreover, designs to facilitate planar focal lenses and source illusion devices can also be accomplished. The proposed flexible and versatile strategy to manipulate elastic waves has potential applications ranging from structural fault detection to vibration/noise control.

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

    Science.gov (United States)

    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.

  9. Extended Delivery Time Analysis for Secondary Packet Transmission With Adaptive Modulation Under Interweave Cognitive Implementation

    KAUST Repository

    Wang, Wen-Jing

    2017-05-02

    Cognitive radio communication can opportunistically access underutilized spectrum for emerging wireless applications. With interweave cognitive implementation, a secondary user (SU) transmits only if primary user does not occupy the channel and waits for transmission otherwise. Therefore, secondary packet transmission involves both transmission periods and waiting periods. The resulting extended delivery time (EDT) is critical to the throughput analysis of secondary system. In this paper, we study the EDT of secondary packet transmission with adaptive modulation under interweave implementation to facilitate the delay analysis of such cognitive radio system. In particular, we propose an analytical framework to derive the probability density functions of EDT considering random-length SU transmission and waiting periods. We also present selected numerical results to illustrate the mathematical formulations and to verify our analytical approach.

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

    KAUST Repository

    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.

  11. Effects of tonotopicity, adaptation, modulation tuning, and temporal coherence in “primitive” auditory stream segregation

    DEFF Research Database (Denmark)

    Christiansen, Simon Krogholt; Jepsen, Morten Løve; Dau, Torsten

    2014-01-01

    The perceptual organization of two-tone sequences into auditory streams was investigated using a modeling framework consisting of an auditory pre-processing front end [Dau et al., J. Acoust. Soc. Am. 102, 2892–2905 (1997)] combined with a temporal coherence-analysis back end [Elhilali et al......., Neuron 61, 317–329 (2009)]. Two experimental paradigms were considered: (i) Stream segregation as a function of tone repetition time (TRT) and frequency separation (Df) and (ii) grouping of distant spectral components based on onset/offset synchrony. The simulated and experimental results of the present...... study supported the hypothesis that forward masking enhances the ability to perceptually segregate spectrally close tone sequences. Furthermore, the modeling suggested that effects of neural adaptation and processing though modulation-frequency selective filters may enhance the sensitivity to onset...

  12. Marginal adaptation and CAD-CAM technology: A systematic review of restorative material and fabrication techniques.

    Science.gov (United States)

    Papadiochou, Sofia; Pissiotis, Argirios L

    2018-04-01

    The comparative assessment of computer-aided design and computer-aided manufacturing (CAD-CAM) technology and other fabrication techniques pertaining to marginal adaptation should be documented. Limited evidence exists on the effect of restorative material on the performance of a CAD-CAM system relative to marginal adaptation. The purpose of this systematic review was to investigate whether the marginal adaptation of CAD-CAM single crowns, fixed dental prostheses, and implant-retained fixed dental prostheses or their infrastructures differs from that obtained by other fabrication techniques using a similar restorative material and whether it depends on the type of restorative material. An electronic search of English-language literature published between January 1, 2000, and June 30, 2016, was conducted of the Medline/PubMed database. Of the 55 included comparative studies, 28 compared CAD-CAM technology with conventional fabrication techniques, 12 contrasted CAD-CAM technology and copy milling, 4 compared CAD-CAM milling with direct metal laser sintering (DMLS), and 22 investigated the performance of a CAD-CAM system regarding marginal adaptation in restorations/infrastructures produced with different restorative materials. Most of the CAD-CAM restorations/infrastructures were within the clinically acceptable marginal discrepancy (MD) range. The performance of a CAD-CAM system relative to marginal adaptation is influenced by the restorative material. Compared with CAD-CAM, most of the heat-pressed lithium disilicate crowns displayed equal or smaller MD values. Slip-casting crowns exhibited similar or better marginal accuracy than those fabricated with CAD-CAM. Cobalt-chromium and titanium implant infrastructures produced using a CAD-CAM system elicited smaller MD values than zirconia. The majority of cobalt-chromium restorations/infrastructures produced by DMLS displayed better marginal accuracy than those fabricated with the casting technique. Compared with copy

  13. A single antenna interference cancellation and adaptive technique based on ALOE

    Directory of Open Access Journals (Sweden)

    Xu Han

    2017-02-01

    Full Text Available A new type of single antenna interference cancellation (SAIC algorithm based on ALOE filtering module is introduced for co-channel interference cancellation in GSM/GPRS/EDGE downlink without changing the link structure of traditional receiver.Meanwhile,an adjacent frequency adaptive detection based on power spectrum estimation method is introduced to solve adjacent frequency interference and complex interference.Compared with traditional energy noise estimation method,the new method has simpler structure,less complexity,and can effectively improve the adaptability for various scenarios.The simulation results show that it can raise the resistance to co-channel frequency interference and adjacent frequency interference in multimode chips with low complexity,which improves the quality of 2G voice communication.

  14. New Technique for Luminosity Measurement Using 3D Pixel Modules in the ATLAS IBL Detector

    CERN Document Server

    Liu, Peilian; The ATLAS collaboration

    2017-01-01

    The Insertable b-Layer ( IBL ) is the innermost layer of the ATLAS tracking system. It consists of planar pixel modules in the central region and 3D modules at two extremities. We use the cluster length distributions in 3D sensor modules of the IBL to determine the number of primary charged particles per event and suppress backgrounds. This Pixel Cluster Counting ( PCC ) algorithm provides a bunch-by-bunch luminosity measurement. An accurate luminosity measurement is a key component for precision measurements at the Large Hadron Collider and one of the largest uncertainties on the luminosity determination in ATLAS arises from the long-term stability of the measurement technique. The comparison of the PCC algorithm with other existing algorithms provides key insights in assessing and reducing such uncertainty.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  16. Optimal space communications techniques. [discussion of video signals and delta modulation

    Science.gov (United States)

    Schilling, D. L.

    1974-01-01

    The encoding of video signals using the Song Adaptive Delta Modulator (Song ADM) is discussed. The video signals are characterized as a sequence of pulses having arbitrary height and width. Although the ADM is suited to tracking signals having fast rise times, it was found that the DM algorithm (which permits an exponential rise for estimating an input step) results in a large overshoot and an underdamped response to the step. An overshoot suppression algorithm which significantly reduces the ringing while not affecting the rise time is presented along with formuli for the rise time and the settling time. Channel errors and their effect on the DM encoded bit stream were investigated.

  17. A Novel MEMS Gyro North Finder Design Based on the Rotation Modulation Technique.

    Science.gov (United States)

    Zhang, Yongjian; Zhou, Bin; Song, Mingliang; Hou, Bo; Xing, Haifeng; Zhang, Rong

    2017-04-28

    Gyro north finders have been widely used in maneuvering weapon orientation, oil drilling and other areas. This paper proposes a novel Micro-Electro-Mechanical System (MEMS) gyroscope north finder based on the rotation modulation (RM) technique. Two rotation modulation modes (static and dynamic modulation) are applied. Compared to the traditional gyro north finders, only one single MEMS gyroscope and one MEMS accelerometer are needed, reducing the total cost since high-precision gyroscopes and accelerometers are the most expensive components in gyro north finders. To reduce the volume and enhance the reliability, wireless power and wireless data transmission technique are introduced into the rotation modulation system for the first time. To enhance the system robustness, the robust least square method (RLSM) and robust Kalman filter (RKF) are applied in the static and dynamic north finding methods, respectively. Experimental characterization resulted in a static accuracy of 0.66° and a dynamic repeatability accuracy of 1°, respectively, confirming the excellent potential of the novel north finding system. The proposed single gyro and single accelerometer north finding scheme is universal, and can be an important reference to both scientific research and industrial applications.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. Brazilian cross-cultural adaptation of the DocCom online module: communication for teamwork

    Directory of Open Access Journals (Sweden)

    Tatiane Angélica Phelipini Borges

    2017-09-01

    Full Text Available ABSTRACT Objective: to carry out the cross-cultural adaptation of DocCom online module 38, which deals with teamwork communication into Portuguese for the Brazilian contexto. Method: the transcultural translation and adaptation were accomplished through initial translations, synthesis of the translations, evaluation and synthesis by a committee of experts, analysis by translators and back translation, pre-test with nurses and undergraduate students in Nursing, and analysis of the translators to obtain the final material. Results: in evaluation and synthesis of the translated version with the original version by the expert committee, the items obtained higher than 80% agreement. Few modifications were suggested according to the analysis by pretest participants. The final version was adequate to the proposed context and its purpose. Conclusion: it is believed that by making this new teaching-learning strategy of communication skills and competencies for teamwork available, it can be used systematically in undergraduate and postgraduate courses in the health area in Brazil in order to contribute to training professionals, and also towards making advances in this field.

  20. Brazilian cross-cultural adaptation of the DocCom online module: communication for teamwork 1

    Science.gov (United States)

    Borges, Tatiane Angélica Phelipini; Vannuchi, Marli Terezinha Oliveira; Grosseman, Suely; González, Alberto Durán

    2017-01-01

    ABSTRACT Objective: to carry out the cross-cultural adaptation of DocCom online module 38, which deals with teamwork communication into Portuguese for the Brazilian contexto. Method: the transcultural translation and adaptation were accomplished through initial translations, synthesis of the translations, evaluation and synthesis by a committee of experts, analysis by translators and back translation, pre-test with nurses and undergraduate students in Nursing, and analysis of the translators to obtain the final material. Results: in evaluation and synthesis of the translated version with the original version by the expert committee, the items obtained higher than 80% agreement. Few modifications were suggested according to the analysis by pretest participants. The final version was adequate to the proposed context and its purpose. Conclusion: it is believed that by making this new teaching-learning strategy of communication skills and competencies for teamwork available, it can be used systematically in undergraduate and postgraduate courses in the health area in Brazil in order to contribute to training professionals, and also towards making advances in this field.

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

    KAUST Repository

    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.

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

    Science.gov (United States)

    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.

  3. Sub-module Short Circuit Fault Diagnosis in Modular Multilevel Converter Based on Wavelet Transform and Adaptive Neuro Fuzzy Inference System

    DEFF Research Database (Denmark)

    Liu, Hui; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    by employing wavelet transform under different fault conditions. Then the fuzzy logic rules are automatically trained based on the fuzzified fault features to diagnose the different faults. Neither additional sensor nor the capacitor voltages are needed in the proposed method. The high accuracy, good...... for continuous operation and post-fault maintenance. In this article, a fault diagnosis technique is proposed for the short circuit fault in a modular multi-level converter sub-module using the wavelet transform and adaptive neuro fuzzy inference system. The fault features are extracted from output phase voltage...

  4. Advanced Packaging Materials and Techniques for High Power TR Module: Standard Flight vs. Advanced Packaging

    Science.gov (United States)

    Hoffman, James Patrick; Del Castillo, Linda; Miller, Jennifer; Jenabi, Masud; Hunter, Donald; Birur, Gajanana

    2011-01-01

    The higher output power densities required of modern radar architectures, such as the proposed DESDynI [Deformation, Ecosystem Structure, and Dynamics of Ice] SAR [Synthetic Aperture Radar] Instrument (or DSI) require increasingly dense high power electronics. To enable these higher power densities, while maintaining or even improving hardware reliability, requires advances in integrating advanced thermal packaging technologies into radar transmit/receive (TR) modules. New materials and techniques have been studied and compared to standard technologies.

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

    Science.gov (United States)

    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.

  6. Neural robust stabilization via event-triggering mechanism and adaptive learning technique.

    Science.gov (United States)

    Wang, Ding; Liu, Derong

    2018-06-01

    The robust control synthesis of continuous-time nonlinear systems with uncertain term is investigated via event-triggering mechanism and adaptive critic learning technique. We mainly focus on combining the event-triggering mechanism with adaptive critic designs, so as to solve the nonlinear robust control problem. This can not only make better use of computation and communication resources, but also conduct controller design from the view of intelligent optimization. Through theoretical analysis, the nonlinear robust stabilization can be achieved by obtaining an event-triggered optimal control law of the nominal system with a newly defined cost function and a certain triggering condition. The adaptive critic technique is employed to facilitate the event-triggered control design, where a neural network is introduced as an approximator of the learning phase. The performance of the event-triggered robust control scheme is validated via simulation studies and comparisons. The present method extends the application domain of both event-triggered control and adaptive critic control to nonlinear systems possessing dynamical uncertainties. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Study on a low complexity adaptive modulation algorithm in OFDM-ROF system with sub-carrier grouping technology

    Science.gov (United States)

    Liu, Chong-xin; Liu, Bo; Zhang, Li-jia; Xin, Xiang-jun; Tian, Qing-hua; Tian, Feng; Wang, Yong-jun; Rao, Lan; Mao, Yaya; Li, Deng-ao

    2018-01-01

    During the last decade, the orthogonal frequency division multiplexing radio-over-fiber (OFDM-ROF) system with adaptive modulation technology is of great interest due to its capability of raising the spectral efficiency dramatically, reducing the effects of fiber link or wireless channel, and improving the communication quality. In this study, according to theoretical analysis of nonlinear distortion and frequency selective fading on the transmitted signal, a low-complexity adaptive modulation algorithm is proposed in combination with sub-carrier grouping technology. This algorithm achieves the optimal performance of the system by calculating the average combined signal-to-noise ratio of each group and dynamically adjusting the origination modulation format according to the preset threshold and user's requirements. At the same time, this algorithm takes the sub-carrier group as the smallest unit in the initial bit allocation and the subsequent bit adjustment. So, the algorithm complexity is only 1 /M (M is the number of sub-carriers in each group) of Fischer algorithm, which is much smaller than many classic adaptive modulation algorithms, such as Hughes-Hartogs algorithm, Chow algorithm, and is in line with the development direction of green and high speed communication. Simulation results show that the performance of OFDM-ROF system with the improved algorithm is much better than those without adaptive modulation, and the BER of the former achieves 10e1 to 10e2 times lower than the latter when SNR values gets larger. We can obtain that this low complexity adaptive modulation algorithm is extremely useful for the OFDM-ROF system.

  8. Radiation transport code with adaptive Mesh Refinement: acceleration techniques and applications

    International Nuclear Information System (INIS)

    Velarde, Pedro; Garcia-Fernaandez, Carlos; Portillo, David; Barbas, Alfonso

    2011-01-01

    We present a study of acceleration techniques for solving Sn radiation transport equations with Adaptive Mesh Refinement (AMR). Both DSA and TSA are considered, taking into account the influence of the interaction between different levels of the mesh structure and the order of approximation in angle. A Hybrid method is proposed in order to obtain better convergence rate and lower computer times. Some examples are presented relevant to ICF and X ray secondary sources. (author)

  9. Adaptation and Implementation of Predictive Maintenance Technique with Nondestructive Testing for Power Plants

    International Nuclear Information System (INIS)

    Jung, Gye Jo; Jung, Nam Gun

    2010-01-01

    Many forces are pressuring utilities to reduce operating and maintenance costs without cutting back on reliability or availability. Many utility managers are re-evaluating maintenance strategies to meet these demands. To utilities how to reduce maintenance costs and extent the effective operating life of equipment, predictive maintenance technique can be adapted. Predictive maintenance had three types program which are in-house program, engineering company program and mixed program. We can approach successful predictive maintenance program with 'smart trust' concept

  10. Minimal-Learning-Parameter Technique Based Adaptive Neural Sliding Mode Control of MEMS Gyroscope

    Directory of Open Access Journals (Sweden)

    Bin Xu

    2017-01-01

    Full Text Available This paper investigates an adaptive neural sliding mode controller for MEMS gyroscopes with minimal-learning-parameter technique. Considering the system uncertainty in dynamics, neural network is employed for approximation. Minimal-learning-parameter technique is constructed to decrease the number of update parameters, and in this way the computation burden is greatly reduced. Sliding mode control is designed to cancel the effect of time-varying disturbance. The closed-loop stability analysis is established via Lyapunov approach. Simulation results are presented to demonstrate the effectiveness of the method.

  11. Marginal adaptation of CAD-CAM onlays: Influence of preparation design and impression technique.

    Science.gov (United States)

    Lima, Fernanda Ferruzzi; Neto, Constantino Fernandes; Rubo, José H; Santos, Gildo Coelho; Moraes Coelho Santos, Maria Jacinta

    2018-03-15

    Factors that may affect the marginal adaptation of computer-aided design and computer-aided manufacturing (CAD-CAM) restorations include preparation design, impression technique, and CAD-CAM system. The influence of impression technique and preparation design on CAD-CAM partial coverage restorations has not been fully addressed. The purpose of this in vitro study was to investigate the influence of direct and indirect digital impression techniques and 2 preparation designs on the marginal adaptation of CAD-CAM onlays. Two mesio-occlusal buccal onlay preparations with reduction of the mesiobuccal cusp were made: conventional preparation (CP) with a 1.2-mm modified shoulder margin and modified preparation (MP) flat cuspal reduction without shoulder. Virtual models were generated from each preparation by using a digital scanner (BlueCam; Dentsply Sirona) from the plastic teeth (direct digital impression) or from the stone dies (indirect digital impression). Onlays were designed using a CAD-CAM system (CEREC 4.0; Dentsply Sirona), and nanoceramic resin blocks (Lava Ultimate Restorative; 3M ESPE) were milled using the CEREC MCX milling machine. Marginal discrepancy was evaluated using an optical stereomicroscope at ×25 magnification in 18 locations distributed along the margins of the preparation. The data were analyzed by using 3-way ANOVA followed by the Tukey HSD test (α=.05). CP presented a statistically significant reduced average marginal adaptation (59 ±50 μm) than did MP (69 ±58 μm) (P<.001). The Tukey HSD test showed the presence of a significantly larger marginal discrepancy in the mesial and buccal locations of MP when compared with CP. Regarding impression techniques, the buccal location presented the smallest average marginal discrepancy in restorations fabricated with indirect impression when compared with direct impression (42 ±33 μm and 60 ±39 μm) (P<.001). The results showed that conventional preparation with a modified shoulder margin

  12. Comparison of online IGRT techniques for prostate IMRT treatment: Adaptive vs repositioning correction

    International Nuclear Information System (INIS)

    Thongphiew, Danthai; Wu, Q. Jackie; Lee, W. Robert; Chankong, Vira; Yoo, Sua; McMahon, Ryan; Yin Fangfang

    2009-01-01

    This study compares three online image guidance techniques (IGRT) for prostate IMRT treatment: bony-anatomy matching, soft-tissue matching, and online replanning. Six prostate IMRT patients were studied. Five daily CBCT scans from the first week were acquired for each patient to provide representative ''snapshots'' of anatomical variations during the course of treatment. Initial IMRT plans were designed for each patient with seven coplanar 15 MV beams on a Eclipse treatment planning system. Two plans were created, one with a PTV margin of 10 mm and another with a 5 mm PTV margin. Based on these plans, the delivered dose distributions to each CBCT anatomy was evaluated to compare bony-anatomy matching, soft-tissue matching, and online replanning. Matching based on bony anatomy was evaluated using the 10 mm PTV margin (''bone10''). Soft-tissue matching was evaluated using both the 10 mm (''soft10'') and 5 mm (''soft5'') PTV margins. Online reoptimization was evaluated using the 5 mm PTV margin (''adapt''). The replanning process utilized the original dose distribution as the basis and linear goal programming techniques for reoptimization. The reoptimized plans were finished in less than 2 min for all cases. Using each IGRT technique, the delivered dose distribution was evaluated on all 30 CBCT scans (6 patientsx5CBCT/patient). The mean minimum dose (in percentage of prescription dose) to the CTV over five treatment fractions were in the ranges of 99%-100%(SD=0.1%-0.8%), 65%-98%(SD=0.4%-19.5%), 87%-99%(SD=0.7%-23.3%), and 95%-99%(SD=0.4%-10.4%) for the adapt, bone10, soft5, and soft10 techniques, respectively. Compared to patient position correction techniques, the online reoptimization technique also showed improvement in OAR sparing when organ motion/deformations were large. For bladder, the adapt technique had the best (minimum) D90, D50, and D30 values for 24, 17, and 15 fractions out of 30 total fractions, while it also had the best D90, D50, and D30 values for

  13. Cytological techniques to analyze meiosis in Arabidopsis arenosa for investigating adaptation to polyploidy.

    Science.gov (United States)

    Higgins, James D; Wright, Kevin M; Bomblies, Kirsten; Franklin, F Chris H

    2014-01-01

    Arabidopsis arenosa is a close relative of the model plant A. thaliana, and exists in nature as stable diploid and autotetraploid populations. Natural tetraploids have adapted to whole genome duplication and do not commonly show meiotic errors such as multivalent and univalent formation, which can lead to chromosome non-disjunction and reduced fertility. A genome scan for genes strongly differentiated between diploid and autotetraploid A. arenosa identified a subset of meiotic genes that may be responsible for adaptation to polyploid meiosis. To investigate the mechanisms by which A. arenosa adapted to its polyploid state, and the functionality of the identified potentially adaptive polymorphisms, a thorough cytological analysis is required. Therefore, in this chapter we describe methods and techniques to analyze male meiosis in A. arenosa, including optimum plant growth conditions, and immunocytological and cytological approaches developed with the specific purpose of understanding meiotic adaptation in an autotetraploid. In addition we present a meiotic cytological atlas to be used as a reference for particular stages and discuss observations arising from a comparison of meiosis between diploid and autotetraploid A. arenosa.

  14. An Autonomous Self-Aware and Adaptive Fault Tolerant Routing Technique for Wireless Sensor Networks

    Science.gov (United States)

    Abba, Sani; Lee, Jeong-A

    2015-01-01

    We propose an autonomous self-aware and adaptive fault-tolerant routing technique (ASAART) for wireless sensor networks. We address the limitations of self-healing routing (SHR) and self-selective routing (SSR) techniques for routing sensor data. We also examine the integration of autonomic self-aware and adaptive fault detection and resiliency techniques for route formation and route repair to provide resilience to errors and failures. We achieved this by using a combined continuous and slotted prioritized transmission back-off delay to obtain local and global network state information, as well as multiple random functions for attaining faster routing convergence and reliable route repair despite transient and permanent node failure rates and efficient adaptation to instantaneous network topology changes. The results of simulations based on a comparison of the ASAART with the SHR and SSR protocols for five different simulated scenarios in the presence of transient and permanent node failure rates exhibit a greater resiliency to errors and failure and better routing performance in terms of the number of successfully delivered network packets, end-to-end delay, delivered MAC layer packets, packet error rate, as well as efficient energy conservation in a highly congested, faulty, and scalable sensor network. PMID:26295236

  15. Adaptive digital fringe projection technique for high dynamic range three-dimensional shape measurement.

    Science.gov (United States)

    Lin, Hui; Gao, Jian; Mei, Qing; He, Yunbo; Liu, Junxiu; Wang, Xingjin

    2016-04-04

    It is a challenge for any optical method to measure objects with a large range of reflectivity variation across the surface. Image saturation results in incorrect intensities in captured fringe pattern images, leading to phase and measurement errors. This paper presents a new adaptive digital fringe projection technique which avoids image saturation and has a high signal to noise ratio (SNR) in the three-dimensional (3-D) shape measurement of objects that has a large range of reflectivity variation across the surface. Compared to previous high dynamic range 3-D scan methods using many exposures and fringe pattern projections, which consumes a lot of time, the proposed technique uses only two preliminary steps of fringe pattern projection and image capture to generate the adapted fringe patterns, by adaptively adjusting the pixel-wise intensity of the projected fringe patterns based on the saturated pixels in the captured images of the surface being measured. For the bright regions due to high surface reflectivity and high illumination by the ambient light and surfaces interreflections, the projected intensity is reduced just to be low enough to avoid image saturation. Simultaneously, the maximum intensity of 255 is used for those dark regions with low surface reflectivity to maintain high SNR. Our experiments demonstrate that the proposed technique can achieve higher 3-D measurement accuracy across a surface with a large range of reflectivity variation.

  16. An Autonomous Self-Aware and Adaptive Fault Tolerant Routing Technique for Wireless Sensor Networks.

    Science.gov (United States)

    Abba, Sani; Lee, Jeong-A

    2015-08-18

    We propose an autonomous self-aware and adaptive fault-tolerant routing technique (ASAART) for wireless sensor networks. We address the limitations of self-healing routing (SHR) and self-selective routing (SSR) techniques for routing sensor data. We also examine the integration of autonomic self-aware and adaptive fault detection and resiliency techniques for route formation and route repair to provide resilience to errors and failures. We achieved this by using a combined continuous and slotted prioritized transmission back-off delay to obtain local and global network state information, as well as multiple random functions for attaining faster routing convergence and reliable route repair despite transient and permanent node failure rates and efficient adaptation to instantaneous network topology changes. The results of simulations based on a comparison of the ASAART with the SHR and SSR protocols for five different simulated scenarios in the presence of transient and permanent node failure rates exhibit a greater resiliency to errors and failure and better routing performance in terms of the number of successfully delivered network packets, end-to-end delay, delivered MAC layer packets, packet error rate, as well as efficient energy conservation in a highly congested, faulty, and scalable sensor network.

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

    Directory of Open Access Journals (Sweden)

    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.

  18. Adaptive optics scanning laser ophthalmoscope using liquid crystal on silicon spatial light modulator: Performance study with involuntary eye movement

    Science.gov (United States)

    Huang, Hongxin; Toyoda, Haruyoshi; Inoue, Takashi

    2017-09-01

    The performance of an adaptive optics scanning laser ophthalmoscope (AO-SLO) using a liquid crystal on silicon spatial light modulator and Shack-Hartmann wavefront sensor was investigated. The system achieved high-resolution and high-contrast images of human retinas by dynamic compensation for the aberrations in the eyes. Retinal structures such as photoreceptor cells, blood vessels, and nerve fiber bundles, as well as blood flow, could be observed in vivo. We also investigated involuntary eye movements and ascertained microsaccades and drifts using both the retinal images and the aberrations recorded simultaneously. Furthermore, we measured the interframe displacement of retinal images and found that during eye drift, the displacement has a linear relationship with the residual low-order aberration. The estimated duration and cumulative displacement of the drift were within the ranges estimated by a video tracking technique. The AO-SLO would not only be used for the early detection of eye diseases, but would also offer a new approach for involuntary eye movement research.

  19. Closed-loop adaptive optics using a spatial light modulator for sensing and compensating of optical aberrations in ophthalmic applications

    Science.gov (United States)

    Akondi, Vyas; Jewel, Md. Atikur Rahman; Vohnsen, Brian

    2014-09-01

    Sensing and compensating of optical aberrations in closed-loop mode using a single spatial light modulator (SLM) for ophthalmic applications is demonstrated. Notwithstanding the disadvantages of the SLM, in certain cases, this multitasking capability of the device makes it advantageous over existing deformable mirrors (DMs), which are expensive and in general used for aberration compensation alone. A closed-loop adaptive optics (AO) system based on a single SLM was built. Beam resizing optics were used to utilize the large active area of the device and hence make it feasible to generate 137 active subapertures for wavefront sensing. While correcting Zernike aberrations up to fourth order introduced with the help of a DM (for testing purposes), diffraction-limited resolution was achieved. It is shown that matched filter and intensity-weighted centroiding techniques stand out among others. Closed-loop wavefront correction of aberrations in backscattered light from the eyes of three healthy human subjects was demonstrated after satisfactory results were obtained using an artificial eye, which was simulated with a short focal length lens and a sheet of white paper as diffuser. It is shown that the closed-loop AO system based on a single SLM is capable of diffraction-limited correction for ophthalmic applications.

  20. Characterization of ultrashort laser pulses employing self-phase modulation dispersion-scan technique

    Science.gov (United States)

    Sharba, A. B.; Chekhlov, O.; Wyatt, A. S.; Pattathil, R.; Borghesi, M.; Sarri, G.

    2018-03-01

    We present a new phase characterization technique for ultrashort laser pulses that employs self-phase modulation (SPM) in the dispersion scan approach. The method can be implemented by recording a set of nonlinearly modulated spectra generated with a set of known chirp values. The unknown phase of the pulse is retrieved by linking the recorded spectra to the initial spectrum of the pulse via a phase function guessed by a function minimization iterative algorithm. This technique has many advantages over the dispersion scan techniques that use frequency conversion processes. Mainly, the use of SPM cancels out the phase and group velocity mismatch errors and dramatically widens the spectral acceptance of the nonlinear medium and the range of working wavelength. The robustness of the technique is demonstrated with smooth and complex phase retrievals using numerical examples. The method is shown to be not affected by the spatial distribution of the beam or the presence of nonlinear absorption process. In addition, we present an efficient method for phase representation based on a summation of a set of Gaussian functions. The independence of the functions from each other prevents phase coupling of any kind and facilitates a flexible phase representation.

  1. Advanced Intensity-Modulation Continuous-Wave Lidar Techniques for Column CO2 Measurements

    Science.gov (United States)

    Campbell, J. F.; Lin, B.; Obland, M. D.; Liu, Z.; Kooi, S. A.; Fan, T. F.; Nehrir, A. R.; Meadows, B.; Browell, E. V.

    2016-12-01

    Advanced Intensity-Modulation Continuous-Wave Lidar Techniques for Column CO2 MeasurementsJoel F. Campbell1, Bing Lin1, Michael D. Obland1, Zhaoyan Liu1, Susan Kooi2, Tai-Fang Fan2, Amin R. Nehrir1, Byron Meadows1, Edward V. Browell31NASA Langley Research Center, Hampton, VA 23681 2SSAI, NASA Langley Research Center, Hampton, VA 23681 3STARSS-II Affiliate, NASA Langley Research Center, Hampton, VA 23681 AbstractGlobal and regional atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission and the Atmospheric Carbon and Transport (ACT) - America project 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 and airborne platforms to meet the ASCENDS and ACT-America science 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 returns. 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 minimizing 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 sub-meter hyperfine interpolation techniques that takes advantage of the periodicity of the modulation waveforms. The BPSK technique under investigation has excellent auto-correlation properties while possessing a finite bandwidth. These techniques are used in a new data processing

  2. Development of the MCM-D technique for pixel detector modules

    CERN Document Server

    Grah, Christian

    2005-01-01

    This thesis treats a copper--polymer based thin film technology, the MCM-D technique and its application when building hybrid pixel detector modules. The ATLAS experiment at the LHC will be equipped with a pixel detector system. The basic mechanical units of the pixel detector are multi chip modules. The main components of these modules are: 16 electronic chips, a controller chip and a large sensor tile, featuring more than 46000 sensor cells. MCM-D is a superior technique to build the necessary signal bus system and the power distribution system directly on the active sensor tile. In collaboration with the Fraunhofer Institute for Reliability and Microintegration, IZM, the thin film process is reviewed and enhanced. The multi layer system was designed and optimized for the interconnection system as well as for the 46000 pixel contacts. Laboratory measurements on prototypes prove that complex routing schemes for geometrically optimized single chips are suitable and have negligible influence on the front--end ...

  3. Breast-conserving radiation therapy using combined electron and intensity-modulated radiotherapy technique

    International Nuclear Information System (INIS)

    Li, J.G.; Williams, S.S.; Goffinet, D.R.; Boer, A.L.; Xing, L.

    2000-01-01

    An electron beam with appropriate energy was combined with four intensity modulated photon beams. The direction of the electron beam was chosen to be tilted 10-20 laterally from the anteroposterior direction. Two of the intensity-modulated photon beams had the same gantry angles as the conventional tangential fields, whereas the other two beams were rotated 15-25' toward the anteroposterior directions from the first two photon beams. An iterative algorithm was developed which optimizes the weight of the electron beam as well as the fluence profiles of the photon beams for a given patient. Two breast cancer patients with early-stage breast tumors were planned with the new technique and the results were compared with those from 3D planning using tangential fields as well as 9-field intensity-modulated radiotherapy (IMRT) techniques. The combined electron and IMRT plans showed better dose conformity to the target with significantly reduced dose to the ipsilateral lung and, in the case of the left-breast patient, reduced dose to the heart, than the tangential field plans. In both the right-sided and left-sided breast plans, the dose to other normal structures was similar to that from conventional plans and was much smaller than that from the 9-field IMRT plans. The optimized electron beam provided between 70 to 80% of the prescribed dose at the depth of maximum dose of the electron beam. The combined electron and IMRT technique showed improvement over the conventional treatment technique using tangential fields with reduced dose to the ipsilateral lung and the heart. The customized beam directions of the four IMRT fields also kept the dose to other critical structures to a minimum. (author)

  4. Cardiac functional analysis with time-adaptive sensitivity encoding technique: comparison with generalized autocalibrating partially parallel acquisitions technique

    International Nuclear Information System (INIS)

    Lu Minjie; Zhao Shihua; Jiang Shiliang; Liu Yuqing; Zhang Yan; Zhang Puhong

    2007-01-01

    Objective: To assess the clinical application value of time-adaptive sensitivity encoding (TSENSE) with single breath hold true fast imaging with steady-state precession (tree FISP) cine sequences for the left ventricular function in comparison with generalized autocalibrating partially parallel acquisitions (GRAPPA) multi-breath hold true FISP cine sequences. Methods: Thirty healthy adult volunteers [male 21, female 9, age (48 ± 16)y] and 32 with cardiac disease [male 28, female 4, age (49 ± 15)y] were studied for evaluating left ventricular function with use of multi-breath hold GRAPPA and single breath hold TSENSE true FISP left ventficular short axis cine. The ventricular function parameters including ejection fraction (EF), end-diastolic volume (EDV) end-systolic volume (ESV), stroke volume (SV), cardiac output (CO), mean myocardial mass (MM) and heart rate (HR) were calculated by using analysis software (Argus, Simens) after drawing the contour of endocardium and epicardium on TSENSE and GRAPPA cines. A paired-samples t test was used to analyze the difference. Results: In volunteers group, TSENSE technique leads to a decrease in CO comparing with GRAPPA technique [(3.8 ± 0.8) L/min, (4.0 ± 0.9) L/min; t=2.262, P 0.05). In patients group, there was no significant difference for all ventricular functional parameters including EF, EDV, ESV, SV, CO and MM (P>0.05). Conclusion: Compared with muhi-breath hold GRAPPA technique, single breath hold TSENSE technique is a fast, accurate and reproducible method and can be an substitute for GRAPPA to evaluate ventricular function. (authors)

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

    Science.gov (United States)

    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.

  6. Cross-Layer Techniques for Adaptive Video Streaming over Wireless Networks

    Directory of Open Access Journals (Sweden)

    Yufeng Shan

    2005-02-01

    Full Text Available Real-time streaming media over wireless networks is a challenging proposition due to the characteristics of video data and wireless channels. In this paper, we propose a set of cross-layer techniques for adaptive real-time video streaming over wireless networks. The adaptation is done with respect to both channel and data. The proposed novel packetization scheme constructs the application layer packet in such a way that it is decomposed exactly into an integer number of equal-sized radio link protocol (RLP packets. FEC codes are applied within an application packet at the RLP packet level rather than across different application packets and thus reduce delay at the receiver. A priority-based ARQ, together with a scheduling algorithm, is applied at the application layer to retransmit only the corrupted RLP packets within an application layer packet. Our approach combines the flexibility and programmability of application layer adaptations, with low delay and bandwidth efficiency of link layer techniques. Socket-level simulations are presented to verify the effectiveness of our approach.

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

    Science.gov (United States)

    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.

  8. Frequency Adaptive Control Technique for Periodic Runout and Wobble Cancellation in Optical Disk Drives

    Directory of Open Access Journals (Sweden)

    Yee-Pien Yang

    2006-10-01

    Full Text Available Periodic disturbance occurs in various applications on the control of the rotational mechanical systems. For optical disk drives, the spirally shaped tracks are usually not perfectly circular and the assembly of the disk and spindle motor is unavoidably eccentric. The resulting periodic disturbance is, therefore, synchronous with the disk rotation, and becomes particularly noticeable for the track following and focusing servo system. This paper applies a novel adaptive controller, namely Frequency Adaptive Control Technique (FACT, for rejecting the periodic runout and wobble effects in the optical disk drive with dual actuators. The control objective is to attenuate adaptively the specific frequency contents of periodic disturbances without amplifying its rest harmonics. FACT is implemented in a plug-in manner and provides a suitable framework for periodic disturbance rejection in the cases where the fundamental frequencies of the disturbance are alterable. It is shown that the convergence property of parameters in the proposed adaptive algorithm is exponentially stable. It is applicable to both the spindle modes of constant linear velocity (CLV and constant angular velocity (CAV for various operation speeds. The experiments showed that the proposed FACT has successful improvement on the tracking and focusing performance of the CD-ROM, and is extended to various compact disk drives.

  9. Fetal Electrocardiogram Extraction and Analysis Using Adaptive Noise Cancellation and Wavelet Transformation Techniques.

    Science.gov (United States)

    Sutha, P; Jayanthi, V E

    2017-12-08

    Birth defect-related demise is mainly due to congenital heart defects. In the earlier stage of pregnancy, fetus problem can be identified by finding information about the fetus to avoid stillbirths. The gold standard used to monitor the health status of the fetus is by Cardiotachography(CTG), cannot be used for long durations and continuous monitoring. There is a need for continuous and long duration monitoring of fetal ECG signals to study the progressive health status of the fetus using portable devices. The non-invasive method of electrocardiogram recording is one of the best method used to diagnose fetal cardiac problem rather than the invasive methods.The monitoring of the fECG requires development of a miniaturized hardware and a efficient signal processing algorithms to extract the fECG embedded in the mother ECG. The paper discusses a prototype hardware developed to monitor and record the raw mother ECG signal containing the fECG and a signal processing algorithm to extract the fetal Electro Cardiogram signal. We have proposed two methods of signal processing, first is based on the Least Mean Square (LMS) Adaptive Noise Cancellation technique and the other method is based on the Wavelet Transformation technique. A prototype hardware was designed and developed to acquire the raw ECG signal containing the mother and fetal ECG and the signal processing techniques were used to eliminate the noises and extract the fetal ECG and the fetal Heart Rate Variability was studied. Both the methods were evaluated with the signal acquired from a fetal ECG simulator, from the Physionet database and that acquired from the subject. Both the methods are evaluated by finding heart rate and its variability, amplitude spectrum and mean value of extracted fetal ECG. Also the accuracy, sensitivity and positive predictive value are also determined for fetal QRS detection technique. In this paper adaptive filtering technique uses Sign-sign LMS algorithm and wavelet techniques with

  10. Development of multileaf collimator- and compensator-based techniques for modulated electron radiotherapy

    Science.gov (United States)

    Tynan, Patricia Marie

    Modulated electron radiotherapy (MERT) is a new electron therapy technique that uses intensity- and/or energy-modulated electron beams to provide a highly conformal dose of radiation to the treatment volume with low levels of dose deposition outside the treatment volume. Several methods are under investigation for treatment of patients, including the use of photon multileaf collimator-modulated (pMLC-modulated) beams, add-on electron multileaf collimators, and carved bolus materials placed directly on the patient's skin. This project developed a new method of delivering MERT beams using patient-specific milled compensators mounted in the standard electron applicator of a linear accelerator, accomplished through four specific aims. Aim 1: Conduct a feasibility study regarding the application of pMLC- and compensator-based MERT techniques within the clinic. Aim 2: Develop a software system to design compensators for modulated electron radiotherapy. Using MATLAB, an automated process for extracting treatment volume location data from a patient's CT data set was created. This software provides data about the depth to which the compensator must be machined to provide a conformal dose to the tumor. Aim 3: Use the Monte Carlo codes BEAMnrc and DOSXYZnrc to commission electron beams of a Varian 23EX linear accelerator for subsequent use in MERT treatment planning. A 10 cm x 10 cm field was modeled for three different energies (9, 12, and 16 MeV) for a Varian 23EX linear accelerator. Excellent match of the models to physical data was achieved, with less than 2% difference in dose and less than 2 mm difference in the lateral dimensions for the beam profiles. Aim 4: Create and validate a compensator-based MERT treatment plan. Using the coordinate data provided by the program created in Aim 3, a treatment plan was developed using the Monte Carlo code MCSIM for a simulated treatment volume. The resulting plan was manually optimized, resulting in a final dosimetric distribution

  11. Adaptive optics correction based on stochastic parallel gradient descent technique using Zernike polynomials

    Science.gov (United States)

    Ma, Huimin; Qiao, Yan; Shen, Chunshan

    2017-10-01

    Adaptive optics systems based on stochastic parallel gradient descent optimization (SPGD) have yet shown great potential on compensation of phase distortions induced by wave propagation through atmosphere turbulence. One of the key technique is increasing the converge rate of SPGD correction system. In the present study, it is shown that the convergence rate of the algorithm will be greatly reduced with the increase of the number of corrector units. In this paper, an improved SPGD optimization process which is based on Zernike-mode is developed. The optimized object is changed from the voltage to Zernike coefficient. Adaptive optics correction system simulation model base on SPGD for a laser beam projecting system, and the numerical simulation of compensation process of random atmosphere turbulence is proposed. To improve the converge speed, we explore to ameliorate the correction system by controlling the perturbation considering atmosphere aberration proportion. The results show that the system converges smoothly and increasingly after considering the aberration proportion by Zernike correction.

  12. Can adaptive modulation of traits to urban environments facilitate Ricinus communis L. invasiveness?

    Science.gov (United States)

    Goyal, Neha; Pardha-Saradhi, P; Sharma, Gyan P

    2014-11-01

    This paper addresses the phenotypic variation among Ricinus communis L. populations in four urban habitat types (road verges, garbage dumps, construction debris, and natural area) in Delhi, India, by evaluating important traits such as plant height, basal circumference, seeds per plant, seed size, seed weight, specific leaf area, and reproductive index. An important biochemical marker, proline, considered as a good plant performance indicator under stress was also quantified in leaves of R. communis to evaluate its response in different habitats. Interestingly, the species showed significant variation in plant height, specific leaf area, seed size, seed weight, and leaf proline content in different habitat types. Leaf proline content was positively related to plant height, specific leaf area, and seed size while negatively related to the total number of seeds/plant. Interestingly, reproductive index, calculated as a ratio of the total number of seeds to the plant height also showed a negative relation with leaf proline content. Results indicated that R. communis exhibits adaptive modulation of growth, reproductive traits, and leaf proline content in various urban habitats which contributes to invasiveness, range expansion, and establishment of the species. The study also gives evidence of how morphological and physiological traits could directly affect invasiveness of R. communis.

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

    Directory of Open Access Journals (Sweden)

    Jared Maxson

    2015-02-01

    Full Text Available 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.

  14. RETRACTED: Adaptive neuro-fuzzy prediction of modulation transfer function of optical lens system

    Science.gov (United States)

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

    2014-07-01

    This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor. Sections ;1. Introduction; and ;2. Modulation transfer function;, as well as Figures 1-3, plagiarize the article published by N. Gül and M. Efe in Turk J Elec Eng & Comp Sci 18 (2010) 71 (http://journals.tubitak.gov.tr/elektrik/issues/elk-10-18-1/elk-18-1-6-0811-9.pdf). Sections ;4. Adaptive neuro-fuzzy inference system; and ;6. Conclusion; duplicate parts of the articles previously published by the corresponding author et al in ;Expert Systems with Applications; 39 (2012) 13295-13304, http://dx.doi.org/10.1016/j.eswa.2012.05.072 and ;Expert Systems with Applications; 40 (2013) 281-286, http://dx.doi.org/10.1016/j.eswa.2012.07.076. One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper is not under consideration for publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents an abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

  15. Performance Comparison of Adaptive Estimation Techniques for Power System Small-Signal Stability Assessment

    Directory of Open Access Journals (Sweden)

    E. A. Feilat

    2010-12-01

    Full Text Available This paper demonstrates the assessment of the small-signal stability of a single-machine infinite- bus power system under widely varying loading conditions using the concept of synchronizing and damping torques coefficients. The coefficients are calculated from the time responses of the rotor angle, speed, and torque of the synchronous generator. Three adaptive computation algorithms including Kalman filtering, Adaline, and recursive least squares have been compared to estimate the synchronizing and damping torque coefficients. The steady-state performance of the three adaptive techniques is compared with the conventional static least squares technique by conducting computer simulations at different loading conditions. The algorithms are compared to each other in terms of speed of convergence and accuracy. The recursive least squares estimation offers several advantages including significant reduction in computing time and computational complexity. The tendency of an unsupplemented static exciter to degrade the system damping for medium and heavy loading is verified. Consequently, a power system stabilizer whose parameters are adjusted to compensate for variations in the system loading is designed using phase compensation method. The effectiveness of the stabilizer in enhancing the dynamic stability over wide range of operating conditions is verified through the calculation of the synchronizing and damping torque coefficients using recursive least square technique.

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

    Science.gov (United States)

    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.

  17. A software module for the adaptive estimation of steady state auditory evoked potentials.

    Science.gov (United States)

    Middleton, S; Goli, A; Ziarani, A K

    2006-01-01

    A graphical user interface (GUI) implementing a novel technique of fast estimation of steady state auditory evoked potentials (SSAEPs) for rapid assessment of the functionality of the human auditory nervous system is presented. The proposed signal estimator has shown great promise in the fast extraction of weak signals buried under large amounts of noise such as the case with SSAEP signals. Currently, the main technical impediment in the widespread clinical use of the SSAEP testing for hearing assessment is the excessively long measurement time needed for the estimation process due to the presence of large amounts of background noise. The presented software module that is publicly disseminated through the Internet is meant to facilitate the use of an efficient signal processing technique by the hearing researchers. The software environment allows for loading previously recorded SSAEP signals into the workspace for analysis. Moreover, it enables the user to add simulated SSAEP signals to the background EEG for the purpose of testing the capability of the underlying signal processing algorithm.

  18. Obtainment of nuclear power plant dynamic parameters by adaptive mesh technique

    International Nuclear Information System (INIS)

    Carvalho Miranda, W. de.

    1979-01-01

    This thesis involves the problem in determination of the parameters of the Mathematical Model of a Nuclear Reactor, including non-linearity which is considered as a bi-linear system. Being a non-linear model, the determination of its parameters cannot be made with the classical techniques as in obtaining its experimental frequency response. In the present work, we examine the possibility of using a model with parameters that adapt according to a algorithm of Newton type minimization, showing that in the case of the single parameter determination, the method is successful. This work was done, using the CSMP (Continuous System Modelling Program) of IBM 1130 of IME. (author)

  19. Sensitivity of non-steady-state photoelectromotive force-based adaptive photodetectors and characterization techniques.

    Science.gov (United States)

    Stepanov, S I

    1994-02-20

    The light-to-electricity conversion efficiency of the non-steady-state photoelectromotive force effect and its threshold sensitivity for the detection of phase-modulated optical signals and space-charge electric fields are evaluated. It is shown that for the optimal conditions of operation (the carrier spatial frequency is equal to the inverse diffusion length of the photocarriers, the detected frequency is higher than the cutoff frequency of the electromotive force signal, and the load resistance is higher than the resistance of the sample), the generation-recombination noise is approximately equal to the thermal noise of the sample resistance. In this case the threshold sensitivity of the adaptive photodetector without an external dc bias is independent of the parameters of the crystal used and can be only 4√2 times lower than that caused by the generation-recombination noise in a conventional photoresistor. Unlike in photodiodes and photoresistors, the output noise caused by laser intensity fluctuations is of the multiplicative type in the adaptive photodetectors.

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

    International Nuclear Information System (INIS)

    Fareed, Muhammad M; AlAmro, Abdullah S; Bayoumi, Yasser; Tunio, Mutahir A; Ismail, Abdul S; Akasha, Rashad; Mubasher, Mohamed; Al Asiri, Mushabbab

    2013-01-01

    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/m 2 (40 patients) or Cisplatin 100 mg/m 2 (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

  1. High range free space optic transmission using new dual diffuser modulation technique

    Directory of Open Access Journals (Sweden)

    Rahman A.K

    2017-01-01

    Full Text Available Free space optical communication fsoc is vulnerable with fluctuating atmospheric. This paper focus analyzes the finding of new technique dual diffuser modulation (ddm to mitigate the atmospheric turbulence effect. The performance of fsoc under the presence of atmospheric turbulence will cause the laser beam keens to (a beam wander, (b beam spreading and (c scintillation. The most deteriorate the fsoc is scintillation where it affected the wavefront cause to fluctuating signal and ultimately receiver can turn into saturate or loss signal. Ddm approach enhances the detecting bit ‘1’ and bit ‘0’ and improves the power received to combat with turbulence effect. The performance focus on signal-to-noise (snr and bit error rate (ber where the numerical result shows that the ddm technique able to improves the range where estimated approximately 40% improvement under weak turbulence and 80% under strong turbulence.

  2. Infrared image gray adaptive adjusting enhancement algorithm based on gray redundancy histogram-dealing technique

    Science.gov (United States)

    Hao, Zi-long; Liu, Yong; Chen, Ruo-wang

    2016-11-01

    In view of the histogram equalizing algorithm to enhance image in digital image processing, an Infrared Image Gray adaptive adjusting Enhancement Algorithm Based on Gray Redundancy Histogram-dealing Technique is proposed. The algorithm is based on the determination of the entire image gray value, enhanced or lowered the image's overall gray value by increasing appropriate gray points, and then use gray-level redundancy HE method to compress the gray-scale of the image. The algorithm can enhance image detail information. Through MATLAB simulation, this paper compares the algorithm with the histogram equalization method and the algorithm based on gray redundancy histogram-dealing technique , and verifies the effectiveness of the algorithm.

  3. Variable Delay With Directly-Modulated R-SOA and Optical Filters for Adaptive Antenna Radio-Fiber Access

    DEFF Research Database (Denmark)

    Prince, Kamau; Presi, Marco; Chiuchiarelli, Andrea

    2009-01-01

    We present an all-optical adaptive-antenna radio over fiber transport system that uses proven, commercially-available components to effectively deliver standard-compliant optical signaling to adaptive multiantenna arrays for current and emerging radio technology implementations. The system is based...... 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 tested with two...

  4. [Positioning errors of CT common rail technique in intensity-modulated radiotherapy for nasopharyngeal carcinoma].

    Science.gov (United States)

    Tian, Fei; Xu, Zihai; Mo, Li; Zhu, Chaohua; Chen, Chaomin

    2012-11-01

    To evaluate the value of CT common rail technique for application in intensity-modulated radiotherapy for nasopharyngeal carcinoma (NPC). Twenty-seven NPC patients underwent Somatom CT scans using the Siemens CTVision system prior to the commencement of the radiotherapy sessions. The acquired CT images were registered with the planning CT images using the matching function of the system to obtain the linear set-up errors of 3 directions, namely X (left to right), Y (superior to inferior), and Z (anterior to posterior). The errors were then corrected online on the moving couch. The 27 NPC patients underwent a total of 110 CT scans and the displacement deviations of the X, Y and Z directions were -0.16∓1.68 mm, 0.25∓1.66 mm, and 0.33∓1.09 mm, respectively. CT common rail technique can accurately and rapidly measure the space error between the posture and the target area to improve the set-up precision of intensity-modulated radiotherapy for NPC.

  5. Beam shaping to improve holography techniques based on spatial light modulators

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim

    2013-03-01

    Modern holographic techniques based on Spatial Light Modulators get serious benefits from providing uniform intensity distribution of a laser beam: more predictable and reliable operation, higher efficiency of laser energy usage, more simple mathematical description of diffraction transformations, etc. Conversion of Gaussian intensity distribution of TEM00 lasers to flattop one is successfully realized with refractive field mapping beam shapers like piShaper, which operational principle presumes transformation with high flatness of output wavefront, conserving of beam consistency, providing collimated output beam of low divergence, high transmittance, extended depth of field, negligible residual wave aberration, and achromatic design provides capability to work with several laser sources with different wavelengths simultaneously. Applying of these beam shapers brings serious benefits to the Spatial Light Modulator based techniques like Computer Generated Holography, Dot-Matrix mastering of security holograms, holographic data storage. This paper will describe some design basics of refractive beam shapers of the field mapping type and optical layouts of their applying in holographic systems. Examples of real implementations and experimental results will be presented as well.

  6. Thermal adaptation of mesophilic and thermophilic FtsZ assembly by modulation of the critical concentration

    Science.gov (United States)

    Concha-Marambio, Luis; Maldonado, Paula; Lagos, Rosalba; Monasterio, Octavio

    2017-01-01

    Cytokinesis is the last stage in the cell cycle. In prokaryotes, the protein FtsZ guides cell constriction by assembling into a contractile ring-shaped structure termed the Z-ring. Constriction of the Z-ring is driven by the GTPase activity of FtsZ that overcomes the energetic barrier between two protein conformations having different propensities to assemble into polymers. FtsZ is found in psychrophilic, mesophilic and thermophilic organisms thereby functioning at temperatures ranging from subzero to >100°C. To gain insight into the functional adaptations enabling assembly of FtsZ in distinct environmental conditions, we analyzed the energetics of FtsZ function from mesophilic Escherichia coli in comparison with FtsZ from thermophilic Methanocaldococcus jannaschii. Presumably, the assembly may be similarly modulated by temperature for both FtsZ orthologs. The temperature dependence of the first-order rates of nucleotide hydrolysis and of polymer disassembly, indicated an entropy-driven destabilization of the FtsZ-GTP intermediate. This destabilization was true for both mesophilic and thermophilic FtsZ, reflecting a conserved mechanism of disassembly. From the temperature dependence of the critical concentrations for polymerization, we detected a change of opposite sign in the heat capacity, that was partially explained by the specific changes in the solvent-accessible surface area between the free and polymerized states of FtsZ. At the physiological temperature, the assembly of both FtsZ orthologs was found to be driven by a small positive entropy. In contrast, the assembly occurred with a negative enthalpy for mesophilic FtsZ and with a positive enthalpy for thermophilic FtsZ. Notably, the assembly of both FtsZ orthologs is characterized by a critical concentration of similar value (1–2 μM) at the environmental temperatures of their host organisms. These findings suggest a simple but robust mechanism of adaptation of FtsZ, previously shown for eukaryotic

  7. Adaptation of Mycoplasmas to Fluoroquinolones: Modulation of Proteome and Genotoxicity of Extracellular Vesicles of Acholeplasma laidlawii

    Directory of Open Access Journals (Sweden)

    E.S. Medvedeva

    2017-06-01

    Full Text Available The paper is devoted to the comparative analysis of proteomic profiles and genotoxicity of extracellular vesicles produced by cells that differ in sensitivity to ciprofloxacin of Acholeplasma laidlawii strains – the mycoplasma, being a causative agent of mycoplasmoses of plants and animals, as well as the main contaminant of cell cultures. The relevance of the study is determined by the fact that extracellular vesicles – nanostructures surrounded by a membrane mediating intercellular communication and pathogenesis in bacteria are involved in adaptation of A. laidlawii to antimicrobials and present a new type of infects, the study of which is associated with the prospects of determining the mechanisms of host-parasite systems and solution of problems of pathogen control. The present study has been performed with a view of elucidation of the proteome profile features and assessment of the genotoxicity of extracellular vesicles of A. laidlawii in the development of resistance of the mycoplasma to ciprofloxacin – a drug of fluoroquinolone group which is widely used for inhibiting mycoplasmas. To achieve this goal, we have used the standard microbiological methods, as well as the modern physical and chemical methods, including proteomic profiling with help of 1D-LC-ESI-MS/MS, PCR, automatic scanning, and karyotyping system for assessment of the genotoxicity of vesicles. It has been shown that a significant part of vesicular proteome of A. laidlawii strains with differential sensitivity to ciprofloxacin represents the bacterial virulence factors, as well as that the vesicles of all strains exhibit genotoxicity to lymphocytes of human peripheral blood in vitro. The most important of these results is the fact that the development of resistance of A. laidlawii to ciprofloxacin is accompanied by a significant modulation of vesicular proteome and the increase of mitotoxicity to eukaryotic cells. The obtained data are essential for fundamental

  8. Optical signal processing techniques and applications of optical phase modulation in high-speed communication systems

    Science.gov (United States)

    Deng, Ning

    the speed limitation of electronics. Thus, all-optical signal processing techniques are highly desirable to support the necessary optical switching functionalities in future ultrahigh-speed optical packet-switching networks. To cope with the wide use of optical phase-modulated signals, in the thesis, an all-optical logic for DPSK or PSK input signals is developed, for the first time. Based on four-wave mixing in semiconductor optical amplifier, the structure of the logic gate is simple, compact, and capable of supporting ultrafast operation. In addition to the general logic processing, a simple label recognition scheme, as a specific signal processing function, is proposed for phase-modulated label signals. The proposed scheme can recognize any incoming label pattern according to the local pattern, and is potentially capable of handling variable-length label patterns. Optical access network with multicast overlay and centralized light sources. In the arena of optical access networks, wavelength division multiplexing passive optical network (WDM-PON) is a promising technology to deliver high-speed data traffic. However, most of proposed WDM-PONs only support conventional point-to-point service, and cannot meet the requirement of increasing demand on broadcast and multicast service. In this thesis, a simple network upgrade is proposed based on the traditional PON architecture to support both point-to-point and multicast service. In addition, the two service signals are modulated on the same lightwave carrier. The upstream signal is also remodulated on the same carrier at the optical network unit, which can significantly relax the requirement on wavelength management at the network unit.

  9. Experimental evaluation of shape memory alloy actuation technique in adaptive antenna design concepts

    Science.gov (United States)

    Kefauver, W. Neill; Carpenter, Bernie F.

    1994-01-01

    Creation of an antenna system that could autonomously adapt contours of reflecting surfaces to compensate for structural loads induced by a variable environment would maximize performance of space-based communication systems. Design of such a system requires the comprehensive development and integration of advanced actuator, sensor, and control technologies. As an initial step in this process, a test has been performed to assess the use of a shape memory alloy as a potential actuation technique. For this test, an existing, offset, cassegrain antenna system was retrofit with a subreflector equipped with shape memory alloy actuators for surface contour control. The impacts that the actuators had on both the subreflector contour and the antenna system patterns were measured. The results of this study indicate the potential for using shape memory alloy actuation techniques to adaptively control antenna performance; both variations in gain and beam steering capabilities were demonstrated. Future development effort is required to evolve this potential into a useful technology for satellite applications.

  10. Coherent optical adaptive technique improves the spatial resolution of STED microscopy in thick samples

    Science.gov (United States)

    Yan, Wei; Yang, Yanlong; Tan, Yu; Chen, Xun; Li, Yang; Qu, Junle; Ye, Tong

    2018-01-01

    Stimulated emission depletion microscopy (STED) is one of far-field optical microscopy techniques that can provide sub-diffraction spatial resolution. The spatial resolution of the STED microscopy is determined by the specially engineered beam profile of the depletion beam and its power. However, the beam profile of the depletion beam may be distorted due to aberrations of optical systems and inhomogeneity of specimens’ optical properties, resulting in a compromised spatial resolution. The situation gets deteriorated when thick samples are imaged. In the worst case, the sever distortion of the depletion beam profile may cause complete loss of the super resolution effect no matter how much depletion power is applied to specimens. Previously several adaptive optics approaches have been explored to compensate aberrations of systems and specimens. However, it is hard to correct the complicated high-order optical aberrations of specimens. In this report, we demonstrate that the complicated distorted wavefront from a thick phantom sample can be measured by using the coherent optical adaptive technique (COAT). The full correction can effectively maintain and improve the spatial resolution in imaging thick samples. PMID:29400356

  11. Coherent optical adaptive technique improves the spatial resolution of STED microscopy in thick samples.

    Science.gov (United States)

    Yan, Wei; Yang, Yanlong; Tan, Yu; Chen, Xun; Li, Yang; Qu, Junle; Ye, Tong

    2017-06-01

    Stimulated emission depletion microscopy (STED) is one of far-field optical microscopy techniques that can provide sub-diffraction spatial resolution. The spatial resolution of the STED microscopy is determined by the specially engineered beam profile of the depletion beam and its power. However, the beam profile of the depletion beam may be distorted due to aberrations of optical systems and inhomogeneity of specimens' optical properties, resulting in a compromised spatial resolution. The situation gets deteriorated when thick samples are imaged. In the worst case, the sever distortion of the depletion beam profile may cause complete loss of the super resolution effect no matter how much depletion power is applied to specimens. Previously several adaptive optics approaches have been explored to compensate aberrations of systems and specimens. However, it is hard to correct the complicated high-order optical aberrations of specimens. In this report, we demonstrate that the complicated distorted wavefront from a thick phantom sample can be measured by using the coherent optical adaptive technique (COAT). The full correction can effectively maintain and improve the spatial resolution in imaging thick samples.

  12. A technique for adaptive image-guided helical tomotherapy for lung cancer

    International Nuclear Information System (INIS)

    Ramsey, Chester R.; Langen, Katja M.; Kupelian, Patrick A.; Scaperoth, Daniel D.; Meeks, Sanford L.; Mahan, Stephen L.; Seibert, Rebecca M.

    2006-01-01

    Purpose: The gross tumor volume (GTV) for many lung cancer patients can decrease during the course of radiation therapy. As the tumor reduces in size during treatment, the margin added around the GTV effectively becomes larger, which can result in the excessive irradiation of normal lung tissue. The specific goal of this study is to evaluate the feasibility of using image-guided adaptive radiation therapy to adjust the planning target volume weekly based on the previous week's CT image sets that were used for image-guided patient setup. Methods and Materials: Megavoltage computed tomography (MVCT) images of the GTV were acquired daily on a helical tomotherapy system. These images were used to position the patient and to measure reduction in GTV volume. A planning study was conducted to determine the amount of lung-sparing that could have been achieved if adaptive therapy had been used. Treatment plans were created in which the target volumes were reduced after tumor reduction was measured. Results: A total of 158 MVCT imaging sessions were performed on 7 lung patients. The GTV was reduced by 60-80% during the course of treatment. The tumor reduction in the first 60 days of treatment can be modeled using the second-order polynomial R 0.0002t 2 - 0.0219t + 1.0, where R is the percent reduction in GTV, and t is the number of elapsed days. Based on these treatment planning studies, the absolute volume of ipsilateral lung receiving 20 Gy can be reduced between 17% and 23% (21% mean) by adapting the treatment delivery. The benefits of adaptive therapy are the greatest for tumor volumes ≥25 cm 3 and are directly dependent on GTV reduction during treatment. Conclusions: Megavoltage CT-based image guidance can be used to position lung cancer patients daily. This has the potential to decrease margins associated with daily setup error. Furthermore, the adaptive therapy technique described in this article can decrease the volume of healthy lung tissue receiving above 20 Gy

  13. Open-loop operation experiments in a resonator fiber-optic gyro using the phase modulation spectroscopy technique.

    Science.gov (United States)

    Zhang, Xu-lin; Ma, Hui-Iian; Jin, Zhong-he; Ding, Chun

    2006-11-01

    A detection system in the resonator fiber-optic gyro is set up by the phase modulation (PM) spectroscopy technique. The slope of the demodulated curve near the resonant point is found to affect the ultimate sensitivity of the gyro. To maximize the demodulated signal slope, the modulation frequency and index are optimized by the expansion of the Bessel function and optical field overlapping method. Using different PM frequencies for the light waves, the open-loop gyro output signal is observed. The modulation frequency in this PM technique is limited only by the cutoff frequency of the LiNbO3 phase modulators, which can reach several gigahertz. This detection technique and system can be applied to the resonator micro-optic gyro with a less than 10 cm long integrated optical ring.

  14. Water System Adaptation To Hydrological Changes: Module 11, Methods and Tools: Computational Models

    Science.gov (United States)

    This course will introduce students to the fundamental principles of water system adaptation to hydrological changes, with emphasis on data analysis and interpretation, technical planning, and computational modeling. Starting with real-world scenarios and adaptation needs, the co...

  15. Water System Adaptation To Hydrological Changes: Module 8, Regulatory Framework Intersections: Past, Present, and Future

    Science.gov (United States)

    This course will introduce students to the fundamental principles of water system adaptation to hydrological changes, with emphasis on data analysis and interpretation, technical planning, and computational modeling. Starting with real-world scenarios and adaptation needs, the co...

  16. 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

    Directory of Open Access Journals (Sweden)

    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

  17. VIDEO DENOISING USING SWITCHING ADAPTIVE DECISION BASED ALGORITHM WITH ROBUST MOTION ESTIMATION TECHNIQUE

    Directory of Open Access Journals (Sweden)

    V. Jayaraj

    2010-08-01

    Full Text Available A Non-linear adaptive decision based algorithm with robust motion estimation technique is proposed for removal of impulse noise, Gaussian noise and mixed noise (impulse and Gaussian with edge and fine detail preservation in images and videos. The algorithm includes detection of corrupted pixels and the estimation of values for replacing the corrupted pixels. The main advantage of the proposed algorithm is that an appropriate filter is used for replacing the corrupted pixel based on the estimation of the noise variance present in the filtering window. This leads to reduced blurring and better fine detail preservation even at the high mixed noise density. It performs both spatial and temporal filtering for removal of the noises in the filter window of the videos. The Improved Cross Diamond Search Motion Estimation technique uses Least Median Square as a cost function, which shows improved performance than other motion estimation techniques with existing cost functions. The results show that the proposed algorithm outperforms the other algorithms in the visual point of view and in Peak Signal to Noise Ratio, Mean Square Error and Image Enhancement Factor.

  18. Development of a fully automated adaptive unsharp masking technique in digital chest radiograph

    International Nuclear Information System (INIS)

    Abe, Katsumi; Katsuragawa, Shigehiko; Sasaki, Yasuo

    1991-01-01

    We are developing a fully automated adaptive unsharp masking technique with various parameters depending on regional image features of a digital chest radiograph. A chest radiograph includes various regions such as lung fields, retrocardiac area and spine in which their texture patterns and optical densities are extremely different. Therefore, it is necessary to enhance image contrast of each region by each optimum parameter. First, we investigated optimum weighting factors and mask sizes of unsharp masking technique in a digital chest radiograph. Then, a chest radiograph is automatically divided into three segments, one for the lung field, one for the retrocardiac area, and one for the spine, by using histogram analysis of pixel values. Finally, high frequency components of the lung field and retrocardiac area are selectively enhanced with a small mask size and mild weighting factors which are previously determined as optimum parameters. In addition, low frequency components of the spine are enhanced with a large mask size and adequate weighting factors. This processed image shows excellent depiction of the lung field, retrocardiac area and spine simultaneously with optimum contrast. Our image processing technique may be useful for diagnosis of chest radiographs. (author)

  19. Two-photon photoacoustics ultrasound measurement by a loss modulation technique

    Science.gov (United States)

    Lai, Yu-Hung; Chang, Chieh-Feng; Cheng, Yu-Hsiang; Sun, Chi-Kuang

    2013-03-01

    In this work, we investigated the principle of the two-photon absorption (TPA) detection with a loss modulation technique, and first demonstrated the existence of two-photon photoacoustics ultrasound excited by a femtosecond high repetition rate laser. By using the AO modulation with different modulation frequencies, we successfully create the beating of the light signal when the two arms of the beams are both spatial and temporal overlapping. The pulse train of the femtosecond laser causes the narrow band excitation, providing the frequency selectivity and sensitivity. Moreover, the pulse energy is no more than 15nJ/pulse, which is at least 3 orders of magnitude smaller than that of the nanosecond laser, and therefore prevents the thermal damage of the sample. With the help of lock-in detection and a low noise amplifier, we can separate the signal of two-photon absorption from one-photon absorption. We used an ultrasonic transducer to detect the response of the sample, and verified the existence of the two-photon photoacoustics ultrasound generating by the femtosecond laser. Several contrast agents, such as the black carbon solution, the fluorescence dye and the nano-particles, were used in the experiment. In the end, we demonstrated the application, two photo-acoustic imaging, which provides the high spatial resolution (<10μm) and large penetration depth (~1mm), to the simulated biological tissue. This is a milestone to develop the two-photon photoacoustics microscopy, which, in principle, has the great potential to achieve the in vitro and in vivo high resolution deep tissue imaging.

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

    Science.gov (United States)

    Chan, Erwin H W

    2012-10-08

    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.

  1. Control and Modulation Techniques for a Centralized PV Generation System Grid Connected via an Interleaved Inverter

    Directory of Open Access Journals (Sweden)

    Gianluca Brando

    2016-09-01

    Full Text Available In the context of grid connected photovoitaic (PV generation systems, there are two paramount aspects regarding the Maximum Power Point Tracking (MPPT of the photovoltaic units and the continuity of the service. The most diffused MPPT algorithms are based on either perturb and observe, or on an incremental conductance approach and need both PV current and voltage measurements. Several topology reconfigurable converters are also associated with the PV plants, guaranteeing fault-tolerant features. The generation continuity can also be assured by interleaved inverters, which keep the system operating at reduced maximum power in case of failure. In this paper, an evolution of a hysteresis based MPPT algorithm is presented, based on the measurement of only one voltage, together with a novel space vector modulation suitable for a two-channel three-phase grid connected interleaved inverter. The proposed MMPT algorithm and modulation technique are tested by means of several numerical analyses on a PV generation system of about 200 kW maximum power. The results testify the validity of the proposed strategies, showing good performance, even during a fault occurrence and in the presence of deep shading conditions.

  2. Modulation format identification enabled by the digital frequency-offset loading technique for hitless coherent transceiver.

    Science.gov (United States)

    Fu, Songnian; Xu, Zuying; Lu, Jianing; Jiang, Hexun; Wu, Qiong; Hu, Zhouyi; Tang, Ming; Liu, Deming; Chan, Calvin Chun-Kit

    2018-03-19

    We propose a blind and fast modulation format identification (MFI) enabled by the digital frequency-offset (FO) loading technique for hitless coherent transceiver. Since modulation format information is encoded to the FO distribution during digital signal processing (DSP) at the transmitter side (Tx), we can use the fast Fourier transformation based FO estimation (FFT-FOE) method to obtain the FO distribution of individual data block after constant modulus algorithm (CMA) pre-equalization at the receiver side, in order to realize non-data-aided (NDA) and fast MFI. The obtained FO can be also used for subsequent FO compensation (FOC), without additional complexity. We numerically investigate and experimentally verify the proposed MFI with high accuracy and fast format switching among 28 Gbaud dual-polarization (DP)-4/8/16/64QAM, time domain hybrid-4/16QAM, and set partitioning (SP)-128QAM. In particular, the proposed MFI brings no performance degradation, in term of tolerance of amplified spontaneous emission (ASE) noise, laser linewidth, and fiber nonlinearity. Finally, a hitless coherent transceiver enabled by the proposed MFI with switching-block of only 2048 symbols is demonstrated over 1500 km standard single mode fiber (SSMF) transmission.

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

    Science.gov (United States)

    Lopez-Diaz, D; Merino, C; Velázquez, M M

    2015-11-11

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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…

  6. How does sacral modulation work best? Placement and programming techniques to maximize efficacy.

    Science.gov (United States)

    Amend, Bastian; Khalil, Mahmoud; Kessler, Thomas M; Sievert, Karl-Dietrich

    2011-10-01

    Since receiving approval from the US Food and Drug Administration in 1997, sacral neuromodulation (SNM) has become the recommended treatment of urinary urge incontinence, urgency-frequency, nonobstructive urinary retention, and fecal incontinence. The manufacturer has introduced different technical modifications while surgeons and researchers have adapted and published various innovations and alterations of the technique. This review summarizes the current knowledge and recommendations of SNM preoperative decision making, the implantation technique, and available programming parameters and algorithms based on MEDLINE research, manufacturer instructions, and the approach of an experienced neurourological team. The primary steps and technical aspects to optimize SNM efficacy were the introduction of the tined-lead electrode and the development of the InterStim II impulse generator (both developed by Medtronic, Inc., Minneapolis, MN). The initiation of the staged implantation technique for sequential evaluation and implantation with the definitive quadripolar electrode completes the treatment algorithm so that an increased responder rate of SNM for all indications can be achieved. © Springer Science+Business Media, LLC 2011

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

    Science.gov (United States)

    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.

  8. Fast correction approach for wavefront sensorless adaptive optics based on a linear phase diversity technique.

    Science.gov (United States)

    Yue, Dan; Nie, Haitao; Li, Ye; Ying, Changsheng

    2018-03-01

    Wavefront sensorless (WFSless) adaptive optics (AO) systems have been widely studied in recent years. To reach optimum results, such systems require an efficient correction method. This paper presents a fast wavefront correction approach for a WFSless AO system mainly based on the linear phase diversity (PD) technique. The fast closed-loop control algorithm is set up based on the linear relationship between the drive voltage of the deformable mirror (DM) and the far-field images of the system, which is obtained through the linear PD algorithm combined with the influence function of the DM. A large number of phase screens under different turbulence strengths are simulated to test the performance of the proposed method. The numerical simulation results show that the method has fast convergence rate and strong correction ability, a few correction times can achieve good correction results, and can effectively improve the imaging quality of the system while needing fewer measurements of CCD data.

  9. Adaptation.

    Science.gov (United States)

    Broom, Donald M

    2006-01-01

    The term adaptation is used in biology in three different ways. It may refer to changes which occur at the cell and organ level, or at the individual level, or at the level of gene action and evolutionary processes. Adaptation by cells, especially nerve cells helps in: communication within the body, the distinguishing of stimuli, the avoidance of overload and the conservation of energy. The time course and complexity of these mechanisms varies. Adaptive characters of organisms, including adaptive behaviours, increase fitness so this adaptation is evolutionary. The major part of this paper concerns adaptation by individuals and its relationships to welfare. In complex animals, feed forward control is widely used. Individuals predict problems and adapt by acting before the environmental effect is substantial. Much of adaptation involves brain control and animals have a set of needs, located in the brain and acting largely via motivational mechanisms, to regulate life. Needs may be for resources but are also for actions and stimuli which are part of the mechanism which has evolved to obtain the resources. Hence pigs do not just need food but need to be able to carry out actions like rooting in earth or manipulating materials which are part of foraging behaviour. The welfare of an individual is its state as regards its attempts to cope with its environment. This state includes various adaptive mechanisms including feelings and those which cope with disease. The part of welfare which is concerned with coping with pathology is health. Disease, which implies some significant effect of pathology, always results in poor welfare. Welfare varies over a range from very good, when adaptation is effective and there are feelings of pleasure or contentment, to very poor. A key point concerning the concept of individual adaptation in relation to welfare is that welfare may be good or poor while adaptation is occurring. Some adaptation is very easy and energetically cheap and

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

    International Nuclear Information System (INIS)

    Huang, Huixian; Lu, Heming; Feng, Guosheng; Jiang, Hailan; Chen, Jiaxin; Cheng, Jinjian; Pang, Qiang; Lu, Zhiping; Gu, Junzhao; Peng, Luxing; Deng, Shan; Mo, Ying; Wu, Danling; Wei, Yinglin

    2015-01-01

    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

  11. Convergence and Efficiency of Adaptive Importance Sampling Techniques with Partial Biasing

    Science.gov (United States)

    Fort, G.; Jourdain, B.; Lelièvre, T.; Stoltz, G.

    2018-04-01

    We propose a new Monte Carlo method to efficiently sample a multimodal distribution (known up to a normalization constant). We consider a generalization of the discrete-time Self Healing Umbrella Sampling method, which can also be seen as a generalization of well-tempered metadynamics. The dynamics is based on an adaptive importance technique. The importance function relies on the weights (namely the relative probabilities) of disjoint sets which form a partition of the space. These weights are unknown but are learnt on the fly yielding an adaptive algorithm. In the context of computational statistical physics, the logarithm of these weights is, up to an additive constant, the free-energy, and the discrete valued function defining the partition is called the collective variable. The algorithm falls into the general class of Wang-Landau type methods, and is a generalization of the original Self Healing Umbrella Sampling method in two ways: (i) the updating strategy leads to a larger penalization strength of already visited sets in order to escape more quickly from metastable states, and (ii) the target distribution is biased using only a fraction of the free-energy, in order to increase the effective sample size and reduce the variance of importance sampling estimators. We prove the convergence of the algorithm and analyze numerically its efficiency on a toy example.

  12. Adaptation of Hybrid FSO/RF Communication System Using Puncturing Technique

    Directory of Open Access Journals (Sweden)

    M. N. Khan

    2016-12-01

    Full Text Available Spectrum of radio frequency (RF communications is limited and expensive to install new applications. Free space optical (FSO communication is a viable technology which offers enormous bandwidth, license free installation, inexpensive deployment and error prone links. The FSO links degrade significantly due to the varying atmospheric and weather conditions (fog, cloud, snow, haze and combination of these. We propose a hybrid FSO/RF communication system which adapts the varying nature of atmosphere and weather. For the adaption of varying atmosphere and weather scenarios, we develop a novel optimization algorithm. The proposed algorithm is based on the well-known puncturing technique. We provide an extrinsic information transfer (EXIT chart for the binary and quaternary mapping scheme for the proposed communication system. We simulate the proposed algorithm for the hybrid communication system and analyze the system performance. The proposed algorithm is computationally less expensive and provide better performance gains over varying atmosphere and weather conditions. The algorithm is suitable for fast speed applications.

  13. Nonlinear adaptive control based on fuzzy sliding mode technique and fuzzy-based compensator.

    Science.gov (United States)

    Nguyen, Sy Dzung; Vo, Hoang Duy; Seo, Tae-Il

    2017-09-01

    It is difficult to efficiently control nonlinear systems in the presence of uncertainty and disturbance (UAD). One of the main reasons derives from the negative impact of the unknown features of UAD as well as the response delay of the control system on the accuracy rate in the real time of the control signal. In order to deal with this, we propose a new controller named CO-FSMC for a class of nonlinear control systems subjected to UAD, which is constituted of a fuzzy sliding mode controller (FSMC) and a fuzzy-based compensator (CO). Firstly, the FSMC and CO are designed independently, and then an adaptive fuzzy structure is discovered to combine them. Solutions for avoiding the singular cases of the fuzzy-based function approximation and reducing the calculating cost are proposed. Based on the solutions, fuzzy sliding mode technique, lumped disturbance observer and Lyapunov stability analysis, a closed-loop adaptive control law is formulated. Simulations along with a real application based on a semi-active train-car suspension are performed to fully evaluate the method. The obtained results reflected that vibration of the chassis mass is insensitive to UAD. Compared with the other fuzzy sliding mode control strategies, the CO-FSMC can provide the best control ability to reduce unwanted vibrations. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  14. Enhancing performance of LCoS-SLM as adaptive optics by using computer-generated holograms modulation software

    Science.gov (United States)

    Tsai, Chun-Wei; Lyu, Bo-Han; Wang, Chen; Hung, Cheng-Chieh

    2017-05-01

    We have already developed multi-function and easy-to-use modulation software that was based on LabVIEW system. There are mainly four functions in this modulation software, such as computer generated holograms (CGH) generation, CGH reconstruction, image trimming, and special phase distribution. Based on the above development of CGH modulation software, we could enhance the performance of liquid crystal on silicon - spatial light modulator (LCoSSLM) as similar as the diffractive optical element (DOE) and use it on various adaptive optics (AO) applications. Through the development of special phase distribution, we are going to use the LCoS-SLM with CGH modulation software into AO technology, such as optical microscope system. When the LCOS-SLM panel is integrated in an optical microscope system, it could be placed on the illumination path or on the image forming path. However, LCOS-SLM provides a program-controllable liquid crystal array for optical microscope. It dynamically changes the amplitude or phase of light and gives the obvious advantage, "Flexibility", to the system

  15. EVALUATION OF INTERNAL ADAPTATION OF CLASS V RESIN COMPOSITE RESTORATIONS USING THREE TECHNIQUES OF POLYMERIZATION

    Science.gov (United States)

    Pereira, José Carlos; D'ALPINO, Paulo Henrique Perlatti; Lopes, Lawrence Gonzaga; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia; de Souza, João Batista

    2007-01-01

    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. PMID:19089100

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

    Directory of Open Access Journals (Sweden)

    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.

  17. Dosimetric comparison of intensity modulated radiotherapy techniques and standard wedged tangents for whole breast radiotherapy

    International Nuclear Information System (INIS)

    Fong, Andrew; Bromley, Regina; Beat, Mardi; Vien, Din; Dineley, Jude; Morgan, Graeme

    2009-01-01

    Full text: Prior to introducing intensity modulated radiotherapy (IMRT) for whole breast radiotherapy (WBRT) into our department we undertook a comparison of the dose parameters of several IMRT techniques and standard wedged tangents (SWT). Our aim was to improve the dose distribution to the breast and to decrease the dose to organs at risk (OAR): heart, lung and contralateral breast (Contra Br). Treatment plans for 20 women (10 right-sided and 10 left-sided) previously treated with SWT for WBRT were used to compare (a) SWT; (b) electronic compensators IMRT (E-IMRT); (c) tangential beam IMRT (T-IMRT); (d) coplanar multi-field IMRT (CP-IMRT); and (e) non-coplanar multi-field IMRT (NCP-IMRT). Plans for the breast were compared for (i) dose homogeneity (DH); (ii) conformity index (CI); (iii) mean dose; (iv) maximum dose; (v) minimum dose; and dose to OAR were calculated (vi) heart; (vii) lung and (viii) Contra Br. Compared with SWT, all plans except CP-IMRT gave improvement in at least two of the seven parameters evaluated. T-IMRT and NCP-IMRT resulted in significant improvement in all parameters except DH and both gave significant reduction in doses to OAR. As on initial evaluation NCP-IMRT is likely to be too time consuming to introduce on a large scale, T-IMRT is the preferred technique for WBRT for use in our department.

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

    Science.gov (United States)

    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.

  19. Adaptive Local Iterative Filtering: A Promising Technique for the Analysis of Nonstationary Signals

    Science.gov (United States)

    Piersanti, M.; Materassi, M.; Cicone, A.; Spogli, L.; Zhou, H.; Ezquer, R. G.

    2018-01-01

    Many real-life signals and, in particular, in the space physics domain, exhibit variations across different temporal scales. Hence, their statistical momenta may depend on the time scale at which the signal is studied. To identify and quantify such variations, a time-frequency analysis has to be performed on these signals. The dependence of the statistical properties of a signal fluctuation on the space and time scales is the distinctive character of systems with nonlinear couplings among different modes. Hence, assessing how the statistics of signal fluctuations vary with scale will be of help in understanding the corresponding multiscale statistics of such dynamics. This paper presents a new multiscale data analysis technique, the adaptive local iterative filtering (ALIF), which allows to describe the multiscale nature of the geophysical signal studied better than via Fourier transform, and improves scale resolution with respect to discrete wavelet transform. The example of geophysical signal, to which ALIF has been applied, is ionospheric radio power scintillation on L band. ALIF appears to be a promising technique to study the small-scale structures of radio scintillation due to ionospheric turbulence.

  20. Parallel implementation of the adaptive neighborhood contrast enhancement technique using histogram-based image partitioning

    Science.gov (United States)

    Rangayyan, Rangaraj M.; Alto, Hilary; Gavrilov, Dmitri

    2001-07-01

    An adaptive neighborhood contrast enhancement (ANCE) technique was developed to improve the perceptibility of features in digitized mammographic images for use in breast cancer screening. The computationally intensive algorithm was implemented on a cluster of 30 COMPAQ Alpha processors using the message passing interface. The parallel implementation of the ANCE technique utilizes histogram- based image partitioning with each partition consisting of a list of gray-level values. The master processor allots one set of gray-level values to each slave processor. Each slave locates all possible seed pixels in the image with the designated gray-level values, grows a region around each pixel, enhances the contrast of the seed and any redundant seed pixels if required, and returns the results to the master. The master then sends a new set of gray-level values to the slave for processing. The subdivision of the original image based on gray-level values guarantees that slave processors do not process the same pixel, and is particularly well suited to the characteristics of the ANCE algorithm. The parallelism value of the problem is in the range of 16 - 20; the performance did not improve significantly when more than 16 processors were used. The performance declined when more than 20 processors were used. The result is a substantial improvement in processing time, leading to the enhancement of 4 K X 4 K pixel images in the range of 30 - 90 s.

  1. Adaptive, Small-Rotation-Based, Corotational Technique for Analysis of 2D Nonlinear Elastic Frames

    Directory of Open Access Journals (Sweden)

    Jaroon Rungamornrat

    2014-01-01

    Full Text Available This paper presents an efficient and accurate numerical technique for analysis of two-dimensional frames accounted for both geometric nonlinearity and nonlinear elastic material behavior. An adaptive remeshing scheme is utilized to optimally discretize a structure into a set of elements where the total displacement can be decomposed into the rigid body movement and one possessing small rotations. This, therefore, allows the force-deformation relationship for the latter part to be established based on small-rotation-based kinematics. Nonlinear elastic material model is integrated into such relation via the prescribed nonlinear moment-curvature relationship. The global force-displacement relation for each element can be derived subsequently using corotational formulations. A final system of nonlinear algebraic equations along with its associated gradient matrix for the whole structure is obtained by a standard assembly procedure and then solved numerically by Newton-Raphson algorithm. A selected set of results is then reported to demonstrate and discuss the computational performance including the accuracy and convergence of the proposed technique.

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

    Directory of Open Access Journals (Sweden)

    Razavi Rouzbeh

    2008-01-01

    Full Text Available Abstract 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  4. ADAPTIVE FINITE ELEMENT MODELING TECHNIQUES FOR THE POISSON-BOLTZMANN EQUATION

    Science.gov (United States)

    HOLST, MICHAEL; MCCAMMON, JAMES ANDREW; YU, ZEYUN; ZHOU, YOUNGCHENG; ZHU, YUNRONG

    2011-01-01

    We consider the design of an effective and reliable adaptive finite element method (AFEM) for the nonlinear Poisson-Boltzmann equation (PBE). We first examine the two-term regularization technique for the continuous problem recently proposed by Chen, Holst, and Xu based on the removal of the singular electrostatic potential inside biomolecules; this technique made possible the development of the first complete solution and approximation theory for the Poisson-Boltzmann equation, the first provably convergent discretization, and also allowed for the development of a provably convergent AFEM. However, in practical implementation, this two-term regularization exhibits numerical instability. Therefore, we examine a variation of this regularization technique which can be shown to be less susceptible to such instability. We establish a priori estimates and other basic results for the continuous regularized problem, as well as for Galerkin finite element approximations. We show that the new approach produces regularized continuous and discrete problems with the same mathematical advantages of the original regularization. We then design an AFEM scheme for the new regularized problem, and show that the resulting AFEM scheme is accurate and reliable, by proving a contraction result for the error. This result, which is one of the first results of this type for nonlinear elliptic problems, is based on using continuous and discrete a priori L∞ estimates to establish quasi-orthogonality. To provide a high-quality geometric model as input to the AFEM algorithm, we also describe a class of feature-preserving adaptive mesh generation algorithms designed specifically for constructing meshes of biomolecular structures, based on the intrinsic local structure tensor of the molecular surface. All of the algorithms described in the article are implemented in the Finite Element Toolkit (FETK), developed and maintained at UCSD. The stability advantages of the new regularization scheme

  5. HybridArc: A novel radiation therapy technique combining optimized dynamic arcs and intensity modulation

    Energy Technology Data Exchange (ETDEWEB)

    Robar, James L., E-mail: james.robar@cdha.nshealth.ca [Department of Radiation Oncology, Dalhousie University, Halifax (Canada); Department of Physics and Atmospheric Science, Dalhousie University, Halifax (Canada); Thomas, Christopher [Department of Radiation Oncology, Dalhousie University, Halifax (Canada)

    2012-01-01

    This investigation focuses on possible dosimetric and efficiency advantages of HybridArc-a novel treatment planning approach combining optimized dynamic arcs with intensity-modulated radiation therapy (IMRT) beams. Application of this technique to two disparate sites, complex cranial tumors, and prostate was examined. HybridArc plans were compared with either dynamic conformal arc (DCA) or IMRT plans to determine whether HybridArc offers a synergy through combination of these 2 techniques. Plans were compared with regard to target volume dose conformity, target volume dose homogeneity, sparing of proximal organs at risk, normal tissue sparing, and monitor unit (MU) efficiency. For cranial cases, HybridArc produced significantly improved dose conformity compared with both DCA and IMRT but did not improve sparing of the brainstem or optic chiasm. For prostate cases, conformity was improved compared with DCA but not IMRT. Compared with IMRT, the dose homogeneity in the planning target volume was improved, and the maximum doses received by the bladder and rectum were reduced. Both arc-based techniques distribute peripheral dose over larger volumes of normal tissue compared with IMRT, whereas HybridArc involved slightly greater volumes of normal tissues compared with DCA. Compared with IMRT, cranial cases required 38% more MUs, whereas for prostate cases, MUs were reduced by 7%. For cranial cases, HybridArc improves dose conformity to the target. For prostate cases, dose conformity and homogeneity are improved compared with DCA and IMRT, respectively. Compared with IMRT, whether required MUs increase or decrease with HybridArc was site-dependent.

  6. Cardiac avoidance in breast radiotherapy: a comparison of simple shielding techniques with intensity-modulated radiotherapy

    International Nuclear Information System (INIS)

    Landau, David; Adams, Elizabeth J.; Webb, Steve; Ross, Gillian

    2001-01-01

    Background and purpose: Adjuvant breast radiotherapy (RT) is now part of the routine care of patients with early breast cancer. However, analysis of the Early Breast Cancer Trialists' Collaborative suggests that patients with the lowest risk of dying of breast cancer are at significant risk of cardiac mortality due to longer relapse-free survival. Patients with a significant amount of heart in the high-dose volume have been shown to be at risk of fatal cardiac events. This study was designed to assess whether conformal planning or intensity-modulated radiotherapy (IMRT) techniques allow reduced cardiac irradiation whilst maintaining full target coverage. Material and methods: Ten patients with early breast cancer were available for computed tomography (CT) planning. Each had at least 1 cm maximum heart depth within the posterior border of conventional tangents. For each patient, plans were generated and compared using dose volume histograms for planning target volume (PTV) and organs at risk. The plans included conventional tangents with and without shielding. The shielding was designed to either completely spare the heart or to shield as much heart as possible without compromising PTV coverage. IMRT plans were also prepared using two- and four-field tangential and six-field arc-like beam arrangements. Results: PTV homogeneity was better for the tangential IMRT techniques. For all patients, cardiac irradiation was reduced by the addition of partial cardiac shielding to conventional tangents, without compromise of PTV coverage. The two- and four-field IMRT techniques also reduced heart doses. The average percentage volume of heart receiving >60% of the prescription dose was 4.4% (range 1.0-7.1%) for conventional tangents, 1.5% (0.2-3.9%) for partial shielding, 2.3% (0.5-4.6%) for the two-field IMRT technique and 2.2% (0.4-5.6%) for the four-field IMRT technique. For patients with larger maximum heart depths the four-field IMRT plan achieved greater heart sparing

  7. Novel security enhancement technique against eavesdropper for OCDMA system using 2-D modulation format with code switching scheme

    Science.gov (United States)

    Singh, Simranjit; Kaur, Ramandeep; Singh, Amanvir; Kaler, R. S.

    2015-03-01

    In this paper, security of the spectrally encoded-optical code division multiplexed access (OCDMA) system is enhanced by using 2-D (orthogonal) modulation technique. This is an effective approach for simultaneous improvement of the system capacity and security. Also, the results show that the hybrid modulation technique proved to be a better option to enhance the data confidentiality at higher data rates using minimum utilization of bandwidth in a multiuser environment. Further, the proposed system performance is compared with the current state-of-the-art OCDMA schemes.

  8. A novel oscillation control for MEMS vibratory gyroscopes using a modified electromechanical amplitude modulation technique

    Science.gov (United States)

    Ma, Wei; Lin, Yiyu; Liu, Siqi; Zheng, Xudong; Jin, Zhonghe

    2017-02-01

    This paper reports a novel oscillation control algorithm for MEMS vibratory gyroscopes using a modified electromechanical amplitude modulation (MEAM) technique, which enhances the robustness against the frequency variation of the driving mode, compared to the conventional EAM (CEAM) scheme. In this approach, the carrier voltage exerted on the proof mass is frequency-modulated by the drive resonant frequency. Accordingly, the pick-up signal from the interface circuit involves a constant-frequency component that contains the amplitude and phase information of the vibration displacement. In other words, this informational detection signal is independent of the mechanical resonant frequency, which varies due to different batches, imprecise micro-fabrication and changing environmental temperature. In this paper, the automatic gain control loop together with the phase-locked loop are simultaneously analyzed using the averaging method and Routh-Hurwitz criterion, deriving the stability condition and the parameter optimization rules of the transient response. Then, a simulation model based on the real system is set up to evaluate the control algorithm. Further, the proposed MEAM method is tested using a field-programmable-gate-array based digital platform on a capacitive vibratory gyroscope. By optimizing the control parameters, the transient response of the drive amplitude reveals a settling time of 45.2 ms without overshoot, according well with the theoretical prediction and simulation results. The first measurement results show that the amplitude variance of the drive displacement is 12 ppm in an hour while the phase standard deviation is as low as 0.0004°. The mode-split gyroscope operating under atmospheric pressure demonstrates an outstanding performance. By virtue of the proposed MEAM method, the bias instability and angle random walk are measured to be 0.9° h-1 (improved by 2.4 times compared to the CEAM method) and 0.068° (√h)-1 (improved by 1.4 times

  9. Radio Frequency Identification (RFID) in medical environment: Gaussian Derivative Frequency Modulation (GDFM) as a novel modulation technique with minimal interference properties.

    Science.gov (United States)

    Rieche, Marie; Komenský, Tomás; Husar, Peter

    2011-01-01

    Radio Frequency Identification (RFID) systems in healthcare facilitate the possibility of contact-free identification and tracking of patients, medical equipment and medication. Thereby, patient safety will be improved and costs as well as medication errors will be reduced considerably. However, the application of RFID and other wireless communication systems has the potential to cause harmful electromagnetic disturbances on sensitive medical devices. This risk mainly depends on the transmission power and the method of data communication. In this contribution we point out the reasons for such incidents and give proposals to overcome these problems. Therefore a novel modulation and transmission technique called Gaussian Derivative Frequency Modulation (GDFM) is developed. Moreover, we carry out measurements to show the inteference properties of different modulation schemes in comparison to our GDFM.

  10. Adaptation

    International Development Research Centre (IDRC) Digital Library (Canada)

    . Dar es Salaam. Durban. Bloemfontein. Antananarivo. Cape Town. Ifrane ... program strategy. A number of CCAA-supported projects have relevance to other important adaptation-related themes such as disaster preparedness and climate.

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

    KAUST Repository

    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.

  12. A Dual-Responsive Nanocomposite toward Climate-Adaptable Solar Modulation for Energy-Saving Smart Windows.

    Science.gov (United States)

    Lee, Heng Yeong; Cai, Yufeng; Bi, Shuguang; Liang, Yen Nan; Song, Yujie; Hu, Xiao Matthew

    2017-02-22

    In this work, a novel fully autonomous photothermotropic material made by hybridization of the poly(N-isopropylacrylamide) (PNIPAM) hydrogel and antimony-tin oxide (ATO) is presented. In this photothermotropic system, the near-infrared (NIR)-absorbing ATO acts as nanoheater to induce the optical switching of the hydrogel. Such a new passive smart window is characterized by excellent NIR shielding, a photothermally activated switching mechanism, enhanced response speed, and solar modulation ability. Systems with 0, 5, 10, and 15 atom % Sb-doped ATO in PNIPAM were investigated, and it was found that a PNIPAM/ATO nanocomposite is able to be photothermally activated. The 10 atom % Sb-doped PNIPAM/ATO exhibits the best response speed and solar modulation ability. Different film thicknesses and ATO contents will affect the response rate and solar modulation ability. Structural stability tests at 15 cycles under continuous exposure to solar irradiation at 1 sun intensity demonstrated the performance stability of such a photothermotropic system. We conclude that such a novel photothermotropic hybrid can be used as a new generation of autonomous passive smart windows for climate-adaptable solar modulation.

  13. A Comparison of Potential IM-CW Lidar Modulation Techniques for ASCENDS CO2 Column Measurements From Space

    Science.gov (United States)

    Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.; Harrison, F. Wallace; Obland, Michael D.; Ismail, Syed

    2014-01-01

    Global atmospheric carbon dioxide (CO2) measurements through the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) Decadal Survey recommended space mission are critical for improving our understanding of CO2 sources and sinks. IM-CW (Intensity Modulated Continuous Wave) lidar techniques are investigated as a means of facilitating CO2 measurements from space to meet the ASCENDS science requirements. In previous laboratory and flight experiments we have successfully used linear swept frequency modulation to discriminate surface lidar returns from intermediate aerosol and cloud contamination. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate clouds, which is a requirement for the inversion of the CO2 column-mixing ratio from the instrument optical depth measurements, has been demonstrated with the linear swept frequency modulation technique. We are concurrently investigating advanced techniques to help improve the auto-correlation properties of the transmitted waveform implemented through physical hardware to make cloud rejection more robust in special restricted scenarios. Several different carrier based modulation techniques are compared including orthogonal linear swept, orthogonal non-linear swept, and Binary Phase Shift Keying (BPSK). Techniques are investigated that reduce or eliminate sidelobes. These techniques have excellent auto-correlation properties while possessing a finite bandwidth (by way of a new cyclic digital filter), which will reduce bias error in the presence of multiple scatterers. Our analyses show that the studied modulation techniques can increase the accuracy of CO2 column measurements from space. A comparison of various properties such as signal to noise ratio (SNR) and time-bandwidth product are discussed.

  14. Flutter signal extracting technique based on FOG and self-adaptive sparse representation algorithm

    Science.gov (United States)

    Lei, Jian; Meng, Xiangtao; Xiang, Zheng

    2016-10-01

    Due to various moving parts inside, when a spacecraft runs in orbits, its structure could get a minor angular vibration, which results in vague image formation of space camera. Thus, image compensation technique is required to eliminate or alleviate the effect of movement on image formation and it is necessary to realize precise measuring of flutter angle. Due to the advantages such as high sensitivity, broad bandwidth, simple structure and no inner mechanical moving parts, FOG (fiber optical gyro) is adopted in this study to measure minor angular vibration. Then, movement leading to image degeneration is achieved by calculation. The idea of the movement information extracting algorithm based on self-adaptive sparse representation is to use arctangent function approximating L0 norm to construct unconstrained noisy-signal-aimed sparse reconstruction model and then solve the model by a method based on steepest descent algorithm and BFGS algorithm to estimate sparse signal. Then taking the advantage of the principle of random noises not able to be represented by linear combination of elements, useful signal and random noised are separated effectively. Because the main interference of minor angular vibration to image formation of space camera is random noises, sparse representation algorithm could extract useful information to a large extent and acts as a fitting pre-process method of image restoration. The self-adaptive sparse representation algorithm presented in this paper is used to process the measured minor-angle-vibration signal of FOG used by some certain spacecraft. By component analysis of the processing results, we can find out that the algorithm could extract micro angular vibration signal of FOG precisely and effectively, and can achieve the precision degree of 0.1".

  15. A Highly Adaptable Generic Event-Based Message Channel Design for Loosely Coupling Software Modules

    National Research Council Canada - National Science Library

    Eryigit, Cihat

    2002-01-01

    .... The new channel design has several demonstrated performance advantages over existing event channel implementations The flexibility and adaptability of the channel package has also been validated by a successful upgrade of the channel mechanism of the SAAM prototype system.

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

    CERN Document Server

    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.

  17. Suppression of phase-induced intensity noise in fibre optic delay line signal processors using an optical phase modulation technique.

    Science.gov (United States)

    Chan, Erwin H W

    2010-10-11

    A technique that can suppress the dominant phase-induced intensity noise in fibre optic delay line signal processors is presented. It is based on phase modulation of the optical carrier to distribute the phase noise at the information band into a high frequency band which can be filtered out. This technique is suitable for suppressing the phase noise in various delay line structures and for integrating in the conventional fibre optic links. It can also suppress the coherent interference effect at the same time. A model for predicting the amount of phase noise reduction in various delay line structures using the optical phase modulation technique is presented for the first time and is experimentally verified. Experimental results demonstrate the technique can achieve a large phase noise reduction in various fibre optic delay line signal processors.

  18. An Approach for Synthesis of Modulated M-Channel FIR Filter Banks Utilizing the Frequency-Response Masking Technique

    Directory of Open Access Journals (Sweden)

    Håkan Johansson

    2007-01-01

    Full Text Available The frequency-response masking (FRM technique was introduced as a means of generating linear-phase FIR filters with narrow transition band and low arithmetic complexity. This paper proposes an approach for synthesizing modulated maximally decimated FIR filter banks (FBs utilizing the FRM technique. A new tailored class of FRM filters is introduced and used for synthesizing nonlinear-phase analysis and synthesis filters. Each of the analysis and synthesis FBs is realized with the aid of only three subfilters, one cosine-modulation block, and one sine-modulation block. The overall FB is a near-perfect reconstruction (NPR FB which in this case means that the distortion function has a linear-phase response but small magnitude errors. Small aliasing errors are also introduced by the FB. However, by allowing these small errors (that can be made arbitrarily small, the arithmetic complexity can be reduced. Compared to conventional cosine-modulated FBs, the proposed ones lower significantly the overall arithmetic complexity at the expense of a slightly increased overall FB delay in applications requiring narrow transition bands. Compared to other proposals that also combine cosine-modulated FBs with the FRM technique, the arithmetic complexity can typically be reduced by 40% in specifications with narrow transition bands. Finally, a general design procedure is given for the proposed FBs and examples are included to illustrate their benefits.

  19. An Approach for Synthesis of Modulated -Channel FIR Filter Banks Utilizing the Frequency-Response Masking Technique

    Directory of Open Access Journals (Sweden)

    Rosenbaum Linnéa

    2007-01-01

    Full Text Available The frequency-response masking (FRM technique was introduced as a means of generating linear-phase FIR filters with narrow transition band and low arithmetic complexity. This paper proposes an approach for synthesizing modulated maximally decimated FIR filter banks (FBs utilizing the FRM technique. A new tailored class of FRM filters is introduced and used for synthesizing nonlinear-phase analysis and synthesis filters. Each of the analysis and synthesis FBs is realized with the aid of only three subfilters, one cosine-modulation block, and one sine-modulation block. The overall FB is a near-perfect reconstruction (NPR FB which in this case means that the distortion function has a linear-phase response but small magnitude errors. Small aliasing errors are also introduced by the FB. However, by allowing these small errors (that can be made arbitrarily small, the arithmetic complexity can be reduced. Compared to conventional cosine-modulated FBs, the proposed ones lower significantly the overall arithmetic complexity at the expense of a slightly increased overall FB delay in applications requiring narrow transition bands. Compared to other proposals that also combine cosine-modulated FBs with the FRM technique, the arithmetic complexity can typically be reduced by in specifications with narrow transition bands. Finally, a general design procedure is given for the proposed FBs and examples are included to illustrate their benefits.

  20. Adapt

    Science.gov (United States)

    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

  1. Influence of a proximal margin elevation technique on marginal adaptation of ceramic inlays.

    Science.gov (United States)

    Zaruba, M; Göhring, T N; Wegehaupt, F J; Attin, T

    2013-03-01

    Evaluating the effect of a proximal margin elevation technique on marginal adaptation of ceramic inlays. Class II MOD-cavities were prepared in 40 human molars and randomly distributed to four groups (n = 10). In group EN (positive control) proximal margins were located in enamel, 1 mm above the cementoenamel junction, while 2 mm below in groups DE-1In, DE-2In and DE. The groups DE-1In, DE-2In and DE simulated subgingival location of the cervical margin. In group DE-1In one 3 mm and in group DE-2In two 1.5 mm composite layers (Tetric) were placed for margin elevation of the proximal cavities using Syntac classic as an adhesive. The proximal cavities of group DE remained untreated and served as a negative control. In all groups, ceramic inlays (Cerec 3D) were adhesively inserted. Replicas were taken before and after thermomechanical loading (1.200.000 cycles, 50/5°C, max. load 49 N). Marginal integrity (tooth-composite, composite-inlay) was evaluated with scanning electron microscopy (200×). Percentage of continuous margin (% of total proximal margin length) was compared between groups before and after cycling using ANOVA and Scheffé post-hoc test. After thermomechanical loading, no significant differences were observed between the different groups with respect to the interface composite-inlay and tooth-composite with margins in dentin. The interface tooth-composite in enamel of group EN was significantly better compared to group DE-2In, which was not different to the negative control group DE and DE-1In. Margin elevation technique by placement of a composite filling in the proximal box before insertion of a ceramic inlay results in marginal integrities not different from margins of ceramic inlays placed in dentin.

  2. The analysis of demodulation characteristic on the resonant optical gyro using frequency modulation technique

    Science.gov (United States)

    Ning, Liang; Guo, Lijun; Fang, Gang; Liu, Cihang

    2015-03-01

    The resonator optic gyro (ROG), which utilizes a resonance frequency change due to the Sagnac effect, is a promising candidate for the next generation inertial rotation sensor. In this paper, we first analyzed the signal detection theory and made the demodulation curve modeling. Second, the ROG demodulation test system is set up using the laser frequency modulation spectroscopy technique. The resonance curve of the resonator is detected by the photodiode (PD) and then demodulated by the LIA. By testing at λ=1550nm, and the free spectral range (FSR), the full width at half maximum (FWHM), the depth and the finesse of resonance are 2191.41MHz, 65.55MHz, 0.9 and 33.43 respectively. Calculated from the demodulation signal, the dynamic range of the gyro is from +2.04×103rad/s to -2.04×103rad/s. The slope K1 of the linear part in the demodulation signal is estimated to be 0.8×10-7V/Hz. A basic agreement between experimental results and theoretical calculated values was achieved.

  3. Five-level inverter with dual reference modulation technique for grid-connected PV system

    Energy Technology Data Exchange (ETDEWEB)

    Rahim, N.A.; Selvaraj, J.; Krismadinata, C. [Centre for Power Electronics, Drives, Automation and Control, Department of Electrical Engineering, University of Malaya, Jalan Pantai Bahru, 50603 Kuala Lumpur (Malaysia)

    2010-03-15

    This paper presents a single-phase five-level grid-connected PV inverter with a novel dual reference modulation technique. Two reference signals identical to each other with an offset equivalent to the amplitude of the triangular carrier signal were used to generate PWM signals. The inverter consists of a full-bridge inverter and an auxiliary circuit comprising four diodes and a switch. The inverter produces output voltage in five levels: zero, +1/2V{sub dc}, V{sub dc}, -1/2V{sub dc} and -V{sub dc}. A digital PI current control algorithm is implemented in DSP TMS320F2812 to keep the current injected into the grid sinusoidal and to have high dynamic performance with low THD. The validity of the proposed inverter is verified through simulation and implemented in a prototype. The experimental results are compared with conventional single-phase three-level grid-connected PWM inverter in terms of THD. (author)

  4. Achieving High Absolute Accuracy for Group-Delay Measurements Using the Modulation Phase-Shift Technique

    Science.gov (United States)

    Dennis, T.; Williams, P. A.

    2005-11-01

    We have developed a modulation phase-shift (MPS) system for measuring relative group delay (RGD) in optical components with high absolute accuracy and simultaneously high temporal and wavelength resolution. Our 200-MHz system has a 3.2-pm wavelength resolution and has demonstrated a group-delay resolution of 0.072 ps for repeated measurements of an artifact based on a hydrogen-cyanide gas cell. The expanded uncertainty (2sigma) is +/-0.46 ps for a single spectral measurement (~ 3.4-pm steps) of a narrow 20-ps group-delay feature of the artifact. To our knowledge, this is the first time that the sources of measurement uncertainty for this technique have been described and quantified. A method for predicting the group delay of the gas-cell artifact from measured absorption spectra is described, and an uncertainty analysis for the prediction method is also presented. The implementation required to achieve results of the highest accuracy for both measurements and predictions is discussed.

  5. Pressure modulation, a new dynamic technique for the electrochemical determination of adsorption, reaction and activation volumes.

    Science.gov (United States)

    Loewe, T; Baltruschat, H

    2005-01-21

    A new dynamic method for the measurement of pressure dependent kinetic and thermodynamic quantities is described and its successful operation demonstrated for two example systems. The pressure was modulated with an amplitude of only +/-1 bar or less by means of a piezo-transducer. The small effect on the reaction rate, potential or charge of the electrode can be detected using the lock in technique. The determination of the reaction volume of the redox couple Fe(CN)6(4-)/Fe(CN)6(3-) served as a control of the validity of the measurement and the reliability of the experimental approach. As a first model system the adsorption of hydrogen on polycrystalline Pt was studied. A volume of adsorption of 4.8 cm3 mol(-1) was found. The partial molar volume for protons in water (upsilon+ = -5.4 cm3 mol(-)) measured by Zana and Yeager, J. Phys. Chem., 1967, 71, 521-536, was used to establish that the partial molar volume of the adsorbed hydrogen was close to zero.

  6. A novel radiation therapy technique for malignant pleural mesothelioma combining electrons with intensity-modulated photons

    International Nuclear Information System (INIS)

    Chan, Maria F.; Chui, Chen S.; Song Yulin; Burman, Chandra; Yorke, Ellen; Della-Biancia, Cesar; Rosenzweig, Kenneth E.; Schupak, Karen

    2006-01-01

    Background and purpose: To investigate the feasibility and potential benefits of combining electron and photon intensity modulated radiotherapy (IMRT) for patients with malignant pleural mesothelioma (MPM). Patients and methods: The planning CT images of 11 MPM patients, six after extrapleural pneumonectomy (EPP) and five after pleurectomy/decortication (P/D), were used for this study. These cases were planned with photon IMRT alone and photon IMRT combined with electrons (IMRT+e). The latter approach incorporated the electron dose into the inverse planning optimization. The resulting doses to the planning target volume (PTV) and relevant critical structures were compared. Results: For all patients, the PTV was well covered and doses to critical structures were clinically acceptable for all patients with both techniques. However, IMRT+e exhibited a distinct advantage in reducing the doses to the liver, ipsilateral kidney, contralateral kidney, and heart (P=0.002, 0.003, 0.025, and 0.001, respectively). Conclusions: This study showed that IMRT or IMRT+e is a viable treatment modality for MPM patients. Both plans can provide excellent target coverage and normal tissue sparing, but with the addition of electron beams, the critical structures can be further spared. Additional refining of the electron contribution is expected to further reduce radiation-induced morbidity

  7. Flexible Riser Monitoring Using Hybrid Magnetic/Optical Strain Gage Techniques through RLS Adaptive Filtering

    Science.gov (United States)

    Pipa, Daniel; Morikawa, Sérgio; Pires, Gustavo; Camerini, Claudio; Santos, JoãoMárcio

    2010-12-01

    Flexible riser is a class of flexible pipes which is used to connect subsea pipelines to floating offshore installations, such as FPSOs (floating production/storage/off-loading unit) and SS (semisubmersible) platforms, in oil and gas production. Flexible risers are multilayered pipes typically comprising an inner flexible metal carcass surrounded by polymer layers and spiral wound steel ligaments, also referred to as armor wires. Since these armor wires are made of steel, their magnetic properties are sensitive to the stress they are subjected to. By measuring their magnetic properties in a nonintrusive manner, it is possible to compare the stress in the armor wires, thus allowing the identification of damaged ones. However, one encounters several sources of noise when measuring electromagnetic properties contactlessly, such as movement between specimen and probe, and magnetic noise. This paper describes the development of a new technique for automatic monitoring of armor layers of flexible risers. The proposed approach aims to minimize these current uncertainties by combining electromagnetic measurements with optical strain gage data through a recursive least squares (RLSs) adaptive filter.

  8. Flexible Riser Monitoring Using Hybrid Magnetic/Optical Strain Gage Techniques through RLS Adaptive Filtering

    Directory of Open Access Journals (Sweden)

    Pipa Daniel

    2010-01-01

    Full Text Available Flexible riser is a class of flexible pipes which is used to connect subsea pipelines to floating offshore installations, such as FPSOs (floating production/storage/off-loading unit and SS (semisubmersible platforms, in oil and gas production. Flexible risers are multilayered pipes typically comprising an inner flexible metal carcass surrounded by polymer layers and spiral wound steel ligaments, also referred to as armor wires. Since these armor wires are made of steel, their magnetic properties are sensitive to the stress they are subjected to. By measuring their magnetic properties in a nonintrusive manner, it is possible to compare the stress in the armor wires, thus allowing the identification of damaged ones. However, one encounters several sources of noise when measuring electromagnetic properties contactlessly, such as movement between specimen and probe, and magnetic noise. This paper describes the development of a new technique for automatic monitoring of armor layers of flexible risers. The proposed approach aims to minimize these current uncertainties by combining electromagnetic measurements with optical strain gage data through a recursive least squares (RLSs adaptive filter.

  9. Marginal Adaptation and Quality of Interfaces in Lithium Disilicate Crowns - Influence of Manufacturing and Cementation Techniques.

    Science.gov (United States)

    Melo Freire, C A; Borges, G A; Caldas, Dbm; Santos, R S; Ignácio, S A; Mazur, R F

    To evaluate the cement line thickness and the interface quality in milled or injected lithium disilicate ceramic restorations and their influence on marginal adaptation using different cement types and different adhesive cementation techniques. Sixty-four bovine teeth were prepared for full crown restoration (7.0±0.5 mm in height, 8.0 mm in cervical diameter, and 4.2 mm in incisal diameter) and were divided into two groups: CAD/CAM automation technology, IPS e.max CAD (CAD), and isostatic injection by heat technology, IPS e.max Press (PRESS). RelyX ARC (ARC) and RelyX U200 resin cements were used as luting agents in two activation methods: initial self-activation and light pre-activation for one second (tack-cure). Next, the specimens were stored in distilled water at 23°C ± 2°C for 72 hours. The cement line thickness was measured in micrometers, and the interface quality received scores according to the characteristics and sealing aspects. The evaluations were performed with an optical microscope, and scanning electron microscope images were presented to demonstrate the various features found in the cement line. For the cement line thickness, data were analyzed with three-way analysis of variance (ANOVA) and the Games-Howell test (α=0.05). For the variable interface quality, the data were analyzed with the Mann-Whitney U-test, the Kruskal-Wallis test, and multiple comparisons nonparametric Dunn test (α=0.05). The ANOVA presented statistical differences among the ceramic restoration manufacturing methods as well as a significant interaction between the manufacturing methods and types of cement (pcement line thickness values when compared to the ARC with both cementation techniques (pmanufacturing methods and cementation techniques. The PRESS ceramics obtained lower scores than did the CAD ceramics when using ARC cement (pcemented with self-adhesive resin cement resulted in a thinner cement line that is statistically different from that of CAD or pressed

  10. Induction of Osmoadaptive Mechanisms and Modulation of Cellular Physiology Help Bacillus licheniformis Strain SSA 61 Adapt to Salt Stress

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Sangeeta; Aggarwal, Chetana; Thakur, Jyoti Kumar; Bandeppa, G. S.; Khan, Md. Aslam; Pearson, Lauren M.; Babnigg, Gyorgy; Giometti, Carol S.; Joachimiak, Andrzej

    2015-01-06

    Bacillus licheniformis strain SSA 61, originally isolated from Sambhar salt lake, was observed to grow even in the presence of 25 % salt stress. Osmoadaptive mechanisms of this halotolerant B. licheniformis strain SSA 61, for long-term survival and growth under salt stress, were determined. Proline was the preferentially accumulated compatible osmolyte. There was also increased accumulation of antioxidants ascorbic acid and glutathione. Among the different antioxidative enzymes assayed, superoxide dismutase played the most crucial role in defense against salt-induced stress in the organism. Adaptation to stress by the organism involved modulation of cellular physiology at various levels. There was enhanced expression of known proteins playing essential roles in stress adaptation, such as chaperones DnaK and GroEL, and general stress protein YfkM and polynucleotide phosphorylase/polyadenylase. Proteins involved in amino acid biosynthetic pathway, ribosome structure, and peptide elongation were also overexpressed. Salt stress-induced modulation of expression of enzymes involved in carbon metabolism was observed. There was up-regulation of a number of enzymes involved in generation of NADH and NADPH, indicating increased cellular demand for both energy and reducing power.

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

    Science.gov (United States)

    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…

  12. Adaptation

    International Development Research Centre (IDRC) Digital Library (Canada)

    Nairobi, Kenya. 28 Adapting Fishing Policy to Climate Change with the Aid of Scientific and Endogenous Knowledge. Cap Verde, Gambia,. Guinea, Guinea Bissau,. Mauritania and Senegal. Environment and Development in the Third World. (ENDA-TM). Dakar, Senegal. 29 Integrating Indigenous Knowledge in Climate Risk ...

  13. A novel amplitude modulated triangular carrier gain linearization technique for SPWM inverter

    OpenAIRE

    Ramkumar Subburam; Jeevananthan Seenithangam; Kamaraj Vijayarajan

    2009-01-01

    This paper presents a new method to extend the linearity of the sinusoidal pulse width modulation (SPWM) to full range of the pulse dropping region. The proposed amplitude modulated triangular carrier PWM method (AMTCPWM) increases the dynamic range of the SPWM control and eliminates the need of nonlinear modulation in the pulse dropping region to reach the square wave boundary. The novel method combines the spectral quality of SPWM with the efficient single-mode linear control. A simple anal...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. Flight control design using a blend of modern nonlinear adaptive and robust techniques

    Science.gov (United States)

    Yang, Xiaolong

    In this dissertation, the modern control techniques of feedback linearization, mu synthesis, and neural network based adaptation are used to design novel control laws for two specific applications: F/A-18 flight control and reusable launch vehicle (an X-33 derivative) entry guidance. For both applications, the performance of the controllers is assessed. As a part of a NASA Dryden program to develop and flight test experimental controllers for an F/A-18 aircraft, a novel method of combining mu synthesis and feedback linearization is developed to design longitudinal and lateral-directional controllers. First of all, the open-loop and closed-loop dynamics of F/A-18 are investigated. The production F/A-18 controller as well as the control distribution mechanism are studied. The open-loop and closed-loop handling qualities of the F/A-18 are evaluated using low order transfer functions. Based on this information, a blend of robust mu synthesis and feedback linearization is used to design controllers for a low dynamic pressure envelope of flight conditions. For both the longitudinal and the lateral-directional axes, a robust linear controller is designed for a trim point in the center of the envelope. Then by including terms to cancel kinematic nonlinearities and variations in the aerodynamic forces and moments over the flight envelope, a complete nonlinear controller is developed. In addition, to compensate for the model uncertainty, linearization error and variations between operating points, neural network based adaptation is added to the designed longitudinal controller. The nonlinear simulations, robustness and handling qualities analysis indicate that the performance is similar to or better than that for the production F/A-18 controllers. When the dynamic pressure is very low, the performance of both the experimental and the production flight controllers is degraded, but Level I handling qualities are still achieved. A new generation of Reusable Launch Vehicles

  16. A new strategy for exploring the hierarchical structure of cancers by adaptively partitioning functional modules from gene expression network.

    Science.gov (United States)

    Xu, Junmei; Jing, Runyu; Liu, Yuan; Dong, Yongcheng; Wen, Zhining; Li, Menglong

    2016-06-28

    The interactions among the genes within a disease are helpful for better understanding the hierarchical structure of the complex biological system of it. Most of the current methodologies need the information of known interactions between genes or proteins to create the network connections. However, these methods meet the limitations in clinical cancer researches because different cancers not only share the common interactions among the genes but also own their specific interactions distinguished from each other. Moreover, it is still difficult to decide the boundaries of the sub-networks. Therefore, we proposed a strategy to construct a gene network by using the sparse inverse covariance matrix of gene expression data, and divide it into a series of functional modules by an adaptive partition algorithm. The strategy was validated by using the microarray data of three cancers and the RNA-sequencing data of glioblastoma. The different modules in the network exhibited specific functions in cancers progression. Moreover, based on the gene expression profiles in the modules, the risk of death was well predicted in the clustering analysis and the binary classification, indicating that our strategy can be benefit for investigating the cancer mechanisms and promoting the clinical applications of network-based methodologies in cancer researches.

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

    CERN Document Server

    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...

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

    Science.gov (United States)

    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.

  19. Adaptability index: quantifying CT tube current modulation performance from dose and quality informatics

    Science.gov (United States)

    Ria, F.; Wilson, J. M.; Zhang, Y.; Samei, E.

    2017-03-01

    The balance between risk and benefit in modern CT scanners is governed by the automatic adaptation mechanisms that adjust x-ray flux for accommodating patient size to achieve certain image noise values. The effectiveness of this adaptation is an important aspect of CT performance and should ideally be characterized in the context of real patient cases. Objective of this study was to characterize CT performance with an index that includes image-noise and radiation dose across a clinical patient population. The study included 1526 examinations performed by three scanners, from two vendors, used for two clinical protocols (abdominopelvic and chest). The dose-patient size and noise-patient size dependencies were linearized, and a 3D-fit was performed for each protocol and each scanner with a planar function. In the fit residual plots the Root Mean Square Error (RMSE) values were estimated as a metric of CT adaptability across the patient population. The RMSE values were between 0.0344 HU1/2 and 0.0215 HU1/2: different scanners offer varying degrees of reproducibility of noise and dose across the population. This analysis could be performed with phantoms, but phantom data would only provide information concerning specific exposure parameters for a scan: instead, a general population comparison is a way to obtain new information related to the relevant clinical adaptability of scanner models. A theoretical relationship between image noise, CTDIvol and patient size was determined based on real patient data. This relationship may provide a new index related to the scanners' adaptability concerning image quality and radiation dose across a patient population.

  20. Reactor Statics Module, RS-9: Multigroup Diffusion Program Using an Exponential Acceleration Technique.

    Science.gov (United States)

    Macek, Victor C.

    The nine Reactor Statics Modules are designed to introduce students to the use of numerical methods and digital computers for calculation of neutron flux distributions in space and energy which are needed to calculate criticality, power distribution, and fuel burnup for both slow neutron and fast neutron fission reactors. The last module, RS-9,…

  1. Recombination hotspots and host susceptibility modulate the adaptive value of recombination during maize streak virus evolution

    Directory of Open Access Journals (Sweden)

    Monjane Adérito L

    2011-12-01

    Full Text Available Abstract Background Maize streak virus -strain A (MSV-A; Genus Mastrevirus, Family Geminiviridae, the maize-adapted strain of MSV that causes maize streak disease throughout sub-Saharan Africa, probably arose between 100 and 200 years ago via homologous recombination between two MSV strains adapted to wild grasses. MSV recombination experiments and analyses of natural MSV recombination patterns have revealed that this recombination event entailed the exchange of the movement protein - coat protein gene cassette, bounded by the two genomic regions most prone to recombination in mastrevirus genomes; the first surrounding the virion-strand origin of replication, and the second around the interface between the coat protein gene and the short intergenic region. Therefore, aside from the likely adaptive advantages presented by a modular exchange of this cassette, these specific breakpoints may have been largely predetermined by the underlying mechanisms of mastrevirus recombination. To investigate this hypothesis, we constructed artificial, low-fitness, reciprocal chimaeric MSV genomes using alternating genomic segments from two MSV strains; a grass-adapted MSV-B, and a maize-adapted MSV-A. Between them, each pair of reciprocal chimaeric genomes represented all of the genetic material required to reconstruct - via recombination - the highly maize-adapted MSV-A genotype, MSV-MatA. We then co-infected a selection of differentially MSV-resistant maize genotypes with pairs of reciprocal chimaeras to determine the efficiency with which recombination would give rise to high-fitness progeny genomes resembling MSV-MatA. Results Recombinants resembling MSV-MatA invariably arose in all of our experiments. However, the accuracy and efficiency with which the MSV-MatA genotype was recovered across all replicates of each experiment depended on the MSV susceptibility of the maize genotypes used and the precise positions - in relation to known recombination hotspots

  2. Recombination hotspots and host susceptibility modulate the adaptive value of recombination during maize streak virus evolution.

    Science.gov (United States)

    Monjane, Adérito L; van der Walt, Eric; Varsani, Arvind; Rybicki, Edward P; Martin, Darren P

    2011-12-02

    Maize streak virus -strain A (MSV-A; Genus Mastrevirus, Family Geminiviridae), the maize-adapted strain of MSV that causes maize streak disease throughout sub-Saharan Africa, probably arose between 100 and 200 years ago via homologous recombination between two MSV strains adapted to wild grasses. MSV recombination experiments and analyses of natural MSV recombination patterns have revealed that this recombination event entailed the exchange of the movement protein - coat protein gene cassette, bounded by the two genomic regions most prone to recombination in mastrevirus genomes; the first surrounding the virion-strand origin of replication, and the second around the interface between the coat protein gene and the short intergenic region. Therefore, aside from the likely adaptive advantages presented by a modular exchange of this cassette, these specific breakpoints may have been largely predetermined by the underlying mechanisms of mastrevirus recombination. To investigate this hypothesis, we constructed artificial, low-fitness, reciprocal chimaeric MSV genomes using alternating genomic segments from two MSV strains; a grass-adapted MSV-B, and a maize-adapted MSV-A. Between them, each pair of reciprocal chimaeric genomes represented all of the genetic material required to reconstruct - via recombination - the highly maize-adapted MSV-A genotype, MSV-MatA. We then co-infected a selection of differentially MSV-resistant maize genotypes with pairs of reciprocal chimaeras to determine the efficiency with which recombination would give rise to high-fitness progeny genomes resembling MSV-MatA. Recombinants resembling MSV-MatA invariably arose in all of our experiments. However, the accuracy and efficiency with which the MSV-MatA genotype was recovered across all replicates of each experiment depended on the MSV susceptibility of the maize genotypes used and the precise positions - in relation to known recombination hotspots - of the breakpoints required to re-create MSV

  3. FPGA Techniques Based New Hybrid Modulation Strategies for Voltage Source Inverters

    Science.gov (United States)

    Sudha, L. U.; Baskaran, J.; Elankurisil, S. A.

    2015-01-01

    This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switching and carrier based pulse width modulation methods. Thus, the harmonic pollution in the power system will be reduced and the power quality will be augmented with better harmonic profile for a target fundamental output voltage. The proposed modulation strategies are simulated in MATLAB r2010a and implemented in a Xilinx spartan 3E-500 FG 320 FPGA processor. The feasibility of these modulation strategies is authenticated through simulation and experimental results. PMID:25821852

  4. FPGA techniques based new hybrid modulation strategies for voltage source inverters.

    Science.gov (United States)

    Sudha, L U; Baskaran, J; Elankurisil, S A

    2015-01-01

    This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switching and carrier based pulse width modulation methods. Thus, the harmonic pollution in the power system will be reduced and the power quality will be augmented with better harmonic profile for a target fundamental output voltage. The proposed modulation strategies are simulated in MATLAB r2010a and implemented in a Xilinx spartan 3E-500 FG 320 FPGA processor. The feasibility of these modulation strategies is authenticated through simulation and experimental results.

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

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    Model errors in adaptive controllers for reduction of broadband noise and vibrations may lead to unstable systems or increased error signals. Previous work has shown that the addition of a low-authority controller that increases damping in the system may lead to improved performance of an adaptive,

  6. Adaptive Multicarrier Modulation: A Convenient Framework for Time-Frequency Processing in Wireless Communications

    OpenAIRE

    Keller, T.; Hanzo, L.

    2000-01-01

    A historical perspective of orthogonal frequency-division multiplexing (OFDM) is given with reference to its literature. Its advantages and disadvantages are reviewed, and its performance is characterized over highly dispersive channels. The effects of both time- and frequency-domain synchronization errors are quantified, and a range of solutions proposed in the recent literature are re-viewed. One of the main objectives of this review is to highlight the recent thinking behind adaptive bit a...

  7. A Highly Adaptable Generic Event-Based Message Channel Design for Loosely Coupling Software Modules

    National Research Council Canada - National Science Library

    Eryigit, Cihat

    2002-01-01

    .... This approach moves programmers focus from component development to component assembly. Event-based programming is one of the techniques that can be used to assemble software components into applications...

  8. Adaptive/learning control of large space structures - System identification techniques. [for multi-configuration flexible spacecraft

    Science.gov (United States)

    Thau, F. E.; Montgomery, R. C.

    1980-01-01

    Techniques developed for the control of aircraft under changing operating conditions are used to develop a learning control system structure for a multi-configuration, flexible space vehicle. A configuration identification subsystem that is to be used with a learning algorithm and a memory and control process subsystem is developed. Adaptive gain adjustments can be achieved by this learning approach without prestoring of large blocks of parameter data and without dither signal inputs which will be suppressed during operations for which they are not compatible. The Space Shuttle Solar Electric Propulsion (SEP) experiment is used as a sample problem for the testing of adaptive/learning control system algorithms.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    KAUST Repository

    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.

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

    KAUST Repository

    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. Applying Swarm Optimization Techniques to Calculate Execution Time for Software Modules

    OpenAIRE

    Nagy Ramadan Darwish; Ahmed A. Mohamed; Bassem S. M. Zohdy

    2016-01-01

    This research aims to calculate the execution time for software modules, using Particle Swarm Optimization (PSO) and Parallel Particle Swarm Optimization (PPSO), in order to calculate the proper time. A comparison is made between MATLAB Code without Algorithm (MCWA), PSO and PPSO to figure out the time produced when executing any software module. The proposed algorithms which include the PPSO increase the speed of executing the algorithm itself, in order to achieve quick results. This researc...

  13. A Simplified Technique for Implant-Abutment Level Impression after Soft Tissue Adaptation around Provisional Restoration

    Directory of Open Access Journals (Sweden)

    Ahmad Kutkut

    2016-05-01

    Full Text Available Impression techniques for implant restorations can be implant level or abutment level impressions with open tray or closed tray techniques. Conventional implant-abutment level impression techniques are predictable for maximizing esthetic outcomes. Restoration of the implant traditionally requires the use of the metal or plastic impression copings, analogs, and laboratory components. Simplifying the dental implant restoration by reducing armamentarium through incorporating conventional techniques used daily for crowns and bridges will allow more general dentists to restore implants in their practices. The demonstrated technique is useful when modifications to implant abutments are required to correct the angulation of malpositioned implants. This technique utilizes conventional crown and bridge impression techniques. As an added benefit, it reduces costs by utilizing techniques used daily for crowns and bridges. The aim of this report is to describe a simplified conventional impression technique for custom abutments and modified prefabricated solid abutments for definitive restorations.

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

    International Nuclear Information System (INIS)

    Moon, Kwon-Ki; Kim, Do-Yeon; Chang, Hoon-Seon; Chang, Young-Woo; Yun, Jae-Hee; Park, Jee-Duck; Kim, Jae-Hack

    2006-01-01

    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

  15. Impact of Volumetric Modulated Arc Therapy Technique on Treatment With Partial Breast Irradiation

    International Nuclear Information System (INIS)

    Qiu Jianjian; Chang Zheng; Wu, Q. Jackie; Yoo, Sua; Horton, Janet; Yin Fangfang

    2010-01-01

    Purpose: To investigate the technical feasibility of volumetric modulated arc therapy (V-MAT) in the delivery of partial breast irradiation (PBI). Methods and Materials: V-MAT and the standard, three-dimensional conformal radiotherapy (3D-CRT), were compared retrospectively in 8 patients previously treated with PBI. These patients' plans were replanned with a single partial arc using V-MAT that included partial blocking to minimize normal tissue dose. Dosimetric parameters were calculated to evaluate plan quality. Quality assurance studies included verifying both the point and the multiple planar doses. Total monitor units and delivery time were also evaluated, and collision clearance was analyzed. Results: Volumes of ipsilateral lung irradiated to 10 Gy (V10) and 20 Gy (V20) by V-MAT were significantly less than those of 3D-CRT (p = 0.03 for V10 and p = 0.025 for V20). The volume of ipsilateral breast irradiated to 5 Gy was significantly less by using V-MAT than with 3D-CRT (p = 0.02), with a ratio of integrated dose of <1.00. The total mean monitor units (489 ± 38) for V-MAT were significantly less than those for 3D-CRT (634 ± 123) (p = 0.017), with a 23% reduction. The average machine delivery time was 1.21 ± 0.10 min for the V-MAT plans and 6.28 ± 1.40 min for the 3D-CRT plans, resulting in a reduction factor of 80.1%. The conformity indexes were 1.3 in the V-MAT plans and 1.5 in the 3D-CRT plans (p = 0.102). Conclusions: V-MAT technology is feasible for PBI patients. Compared to a conventional 3D-CRT technique, it is more efficient, offers equivalent or better dose conformity, delivers lower doses to the ipsilateral lung and breast, and may potentially reduce intrafractional motion.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    Hadsell, M; Chin, E; Li, R; Xing, L; Bush, K

    2014-01-01

    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

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

    KAUST Repository

    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.

  20. Space Vector Pulse Width Modulation Technique Based Design and Simulation of a Three-Phase Voltage Source Converter Systems

    OpenAIRE

    Farhan Beg

    2014-01-01

    A Space Vector based Pulse Width Modulation control technique for the three-phase PWM converter is proposed in this paper. The proposed control scheme is based on a synchronous reference frame model. High performance and efficiency is obtained with regards to the DC bus voltage and the power factor considerations of the PWM rectifier thus leading to low losses. MATLAB/SIMULINK are used as a platform for the simulations and a SIMULINK model is presented in the paper. The r...

  1. Optical coherence tomography of scattering media using frequency-modulated continuous-wave techniques with tunable near-infrared laser

    Science.gov (United States)

    Haberland, Udo; Jansen, Peter; Blazek, Vladimir; Schmitt, Hans J.

    1997-05-01

    A new near-infrared coherent imaging technique that can reveal scattering bodies embedded in highly scattering media is presented. Its underlying principle is extended from frequency modulated continuous wave radar systems. This technique has advantages over low coherence tomography as it does not require the reference mirror to be scanned. The tunable laser is characterized and the system's performance is demonstrated on images recorded from solid scattering phantoms. Furthermore a combination of our chirp-tomography (C-OCT) and laser Doppler perfusion imaging (LDPI) is demonstrated. The influence of moving scatterers on the tomographic images are discussed.

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

    Science.gov (United States)

    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.

  3. Integer-Linear-Programing Optimization in Scalable Video Multicast with Adaptive Modulation and Coding in Wireless Networks

    Directory of Open Access Journals (Sweden)

    Dongyul Lee

    2014-01-01

    Full Text Available 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.

  4. Design and Simulation of Control Technique for Permanent Magnet Synchronous Motor Using Space Vector Pulse Width Modulation

    Science.gov (United States)

    Khan, Mansoor; Yong, Wang; Mustafa, Ehtasham

    2017-07-01

    After the rapid advancement in the field of power electronics devices and drives for last few decades, there are different kinds of Pulse Width Modulation techniques which have been brought to the market. The applications ranging from industrial appliances to military equipment including the home appliances. The vey common application for the PWM is three phase voltage source inverter, which is used to convert DC to AC in the homes to supply the power to the house in case electricity failure, usually named as Un-interrupted Power Supply. In this paper Space Vector Pulse Width Modulation techniques is discussed and analysed under the control technique named as Field Oriented Control. The working and implementation of this technique has been studied by implementing on the three phase bridge inverter. The technique is used to control the Permanente Magnet Synchronous Motor. The drive system is successfully implemented in MATLAB/Simulink using the mathematical equation and algorithm to achieve the satisfactory results. PI type of controller is used to tuned ers of the motothe parametr i.e. torque and current.

  5. A Simplified Technique for Implant-Abutment Level Impression after Soft Tissue Adaptation around Provisional Restoration

    OpenAIRE

    Ahmad Kutkut; Osama Abu-Hammad; Robert Frazer

    2016-01-01

    Impression techniques for implant restorations can be implant level or abutment level impressions with open tray or closed tray techniques. Conventional implant-abutment level impression techniques are predictable for maximizing esthetic outcomes. Restoration of the implant traditionally requires the use of the metal or plastic impression copings, analogs, and laboratory components. Simplifying the dental implant restoration by reducing armamentarium through incorporating conventional techniq...

  6. A Novel Architecture for Adaptive Traffic Control in Network on Chip using Code Division Multiple Access Technique

    OpenAIRE

    Fatemeh. Dehghani; Shahram. Darooei

    2016-01-01

    Network on chip has emerged as a long-term and effective method in Multiprocessor System-on-Chip communications in order to overcome the bottleneck in bus based communication architectures. Efficiency and performance of network on chip is so dependent on the architecture and structure of the network. In this paper a new structure and architecture for adaptive traffic control in network on chip using Code Division Multiple Access technique is presented. To solve the problem of synchronous acce...

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

    International Nuclear Information System (INIS)

    Bhaskoro, Petrus Tri; Gilani, Syed Ihtsham Ul Haq; Aris, Mohd Shiraz

    2013-01-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    International Nuclear Information System (INIS)

    Sponseller, Patricia; Pelly, Nicole; Trister, Andrew; Ford, Eric; Ermoian, Ralph

    2015-01-01

    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

  10. Conducting family meetings in palliative care: themes, techniques, and preliminary evaluation of a communication skills module.

    Science.gov (United States)

    Gueguen, Jennifer A; Bylund, Carma L; Brown, Richard F; Levin, Tomer T; Kissane, David W

    2009-06-01

    To develop a communication skills training module for health care professionals about how to conduct a family meeting in palliative care and to evaluate the module in terms of participant self-efficacy and satisfaction. Forty multispecialty health care professionals from the New York metropolitan area attended a communication skills training module at a Comprehensive Cancer Center about how to conduct a family meeting in oncology. The modular content was based on the Comskil model and current literature in the field. Based on a retrospective pre-post measure, participants reported a significant increase in self-efficacy about their ability to conduct a family meeting. Furthermore, at least 93% of participants expressed their satisfaction with various aspects of the module by agreeing or strongly agreeing with statements on the course evaluation form. Family meetings play a significant role in the palliative care setting, where family support for planning and continuing care is vital to optimize patient care. Although these meetings can be challenging, this communication skills module is effective in increasing the confidence of participants in conducting a family meeting.

  11. Identification and adaptation of linear look-up table parameters using an efficient recursive least-squares technique.

    Science.gov (United States)

    Peyton Jones, James C; Muske, Kenneth R

    2009-10-01

    Linear look-up tables are widely used to approximate and characterize complex nonlinear functional relationships between system input and output. However, both the initial calibration and subsequent real-time adaptation of these tables can be time consuming and prone to error as a result of the large number of table parameters typically required to map the system and the uncertainties and noise in the experimental data on which the calibration is based. In this paper, a new method is presented for identifying or adapting the look-up table parameters using a recursive least-squares based approach. The new method differs from standard recursive least squares algorithms because it exploits the structure of the look-up table equations in order to perform the identification process in a way that is highly computationally and memory efficient. The technique can therefore be implemented within the constraints of typical embedded applications. In the present study, the technique is applied to the identification of the volumetric efficiency look-up table commonly used in gasoline engine fueling strategies. The technique is demonstrated on a Ford 2.0L I4 Duratec engine using time-delayed feedback from a sensor in the exhaust manifold in order to adapt the table parameters online.

  12. A novel amplitude modulated triangular carrier gain linearization technique for SPWM inverter

    Directory of Open Access Journals (Sweden)

    Ramkumar Subburam

    2009-01-01

    Full Text Available This paper presents a new method to extend the linearity of the sinusoidal pulse width modulation (SPWM to full range of the pulse dropping region. The proposed amplitude modulated triangular carrier PWM method (AMTCPWM increases the dynamic range of the SPWM control and eliminates the need of nonlinear modulation in the pulse dropping region to reach the square wave boundary. The novel method combines the spectral quality of SPWM with the efficient single-mode linear control. A simple analytical characterization of the exact method is presented and its effectiveness is demonstrated using simulation for the basic single-phase H-bridge inverter circuit. The hardware results of the designed prototype inverter are presented to validate the betterment of the novel scheme. .

  13. A Dosimetric Evaluation of Conventional Helmet Field Irradiation Versus Two-Field Intensity-Modulated Radiotherapy Technique

    International Nuclear Information System (INIS)

    Yu, James B.; Shiao, Stephen L.; Knisely, Jonathan

    2007-01-01

    Purpose: To compare dosimetric differences between conventional two-beam helmet field irradiation (external beam radiotherapy, EBRT) of the brain and a two-field intensity-modulated radiotherapy (IMRT) technique. Methods and Materials: Ten patients who received helmet field irradiation at our institution were selected for study. External beam radiotherapy portals were planned per usual practice. Intensity-modulated radiotherapy fields were created using the identical field angles as the EBRT portals. Each brain was fully contoured along with the spinal cord to the bottom of the C2 vertebral body. This volume was then expanded symmetrically by 0.5 cm to construct the planning target volume. An IMRT plan was constructed using uniform optimization constraints. For both techniques, the nominal prescribed dose was 3,000 cGy in 10 fractions of 300 cGy using 6-MV photons. Comparative dose-volume histograms were generated for each patient and analyzed. Results: Intensity-modulated radiotherapy improved dose uniformity over EBRT for whole brain radiotherapy. The mean percentage of brain receiving >105% of dose was reduced from 29.3% with EBRT to 0.03% with IMRT. The mean maximum dose was reduced from 3,378 cGy (113%) for EBRT to 3,162 cGy (105%) with IMRT. The mean percent volume receiving at least 98% of the prescribed dose was 99.5% for the conventional technique and 100% for IMRT. Conclusions: Intensity-modulated radiotherapy reduces dose inhomogeneity, particularly for the midline frontal lobe structures where hot spots occur with conventional two-field EBRT. More study needs to be done addressing the clinical implications of optimizing dose uniformity and its effect on long-term cognitive function in selected long-lived patients

  14. Optimization of the sinusoidal phase modulation technique in resonant fiber optic gyro

    Science.gov (United States)

    Wang, Linglan; Li, Hanzhao; Zhang, Jianjie; Ma, Huilian; Jin, Zhonghe

    2017-03-01

    The sinusoidal wave phase modulation and demodulation have been widely used in the signal processing system of the resonant fiber optic gyro (RFOG). An appropriate selection of the modulation frequency is of great importance, for the frequency value directly affects the slope of the demodulation curve at the resonance point which carries the gyro output information. A large demodulation slope is pursued in a high-performance RFOG. In this paper, an analytical expression of the demodulation slope is for the first time deduced in both transmission-type and reflection-type fiber ring resonators without any approximation. The relationship between the slope value and the modulation frequency at the resonance point is accurately calculated. The calculated best modulation frequency maximizing the demodulation slope at the resonance point is different from previous widely used optimal frequency given by the Lorentzian approximation method. More importantly, both theoretical and experimental results indicate that the achieved maximal demodulation slope from the proposed analytical expression method is double of that obtaining from the Lorentzian approximation method.

  15. On Formal Methods for Collective Adaptive System Engineering. Scalable Approximated, Spatial Analysis Techniques. Extended Abstract.

    Directory of Open Access Journals (Sweden)

    Diego Latella

    2016-07-01

    Full Text Available In this extended abstract a view on the role of Formal Methods in System Engineering is briefly presented. Then two examples of useful analysis techniques based on solid mathematical theories are discussed as well as the software tools which have been built for supporting such techniques. The first technique is Scalable Approximated Population DTMC Model-checking. The second one is Spatial Model-checking for Closure Spaces. Both techniques have been developed in the context of the EU funded project QUANTICOL.

  16. Adaptations in responsiveness of brainstem pain-modulating neurons in acute compared to chronic inflammation

    Science.gov (United States)

    Cleary, Daniel R.; Heinricher, Mary M.

    2013-01-01

    Despite similar behavioral hypersensitivity, acute and chronic pain have distinct neural bases. Here we used intraplantar injection of Complete Freund’s Adjuvant (CFA) to directly compare activity of pain-modulating neurons in the rostral ventromedial medulla (RVM) in acute versus chronic inflammation. Heat- and von Frey-evoked withdrawal reflexes and corresponding RVM neuronal activity were recorded in lightly anesthetized animals either during the first hour after CFA injection (acute) or 3–10 days later (chronic). Thermal and modest mechanical hyperalgesia during acute inflammation were associated with increases in the spontaneous activity of pain-facilitating ON-cells and suppression of pain-inhibiting OFF-cells. Acute hyperalgesia was reversed by RVM block, showing that the increased activity of RVM ON-cells is necessary for acute behavioral hypersensitivity. In chronic inflammation, thermal hyperalgesia had resolved, but mechanical hyperalgesia had become pronounced. The spontaneous discharges of ON- and OFF-cells were not different from controls, but the mechanical response thresholds for both cell classes were reduced into the innocuous range. RVM block in the chronic condition worsened mechanical hyperalgesia. These studies identify distinct contributions of RVM ON- and OFF-cells to acute and chronic inflammatory hyperalgesia. During early immune-mediated inflammation, ON-cell spontaneous activity promotes hyperalgesia. After inflammation is established, the anti-nociceptive influence of OFF-cells is dominant, yet the lowered threshold for the OFF-cell pause allows behavioral responses to stimuli that would normally be considered innocuous. The efficacy of OFF-cells in counteracting sensitization of ascending transmission pathways could therefore be an important determining factor in development of chronic inflammatory pain. PMID:23588008

  17. Adaptations in responsiveness of brainstem pain-modulating neurons in acute compared with chronic inflammation.

    Science.gov (United States)

    Cleary, Daniel R; Heinricher, Mary M

    2013-06-01

    Despite similar behavioral hypersensitivity, acute and chronic pain have distinct neural bases. We used intraplantar injection of complete Freund's adjuvant to directly compare activity of pain-modulating neurons in the rostral ventromedial medulla (RVM) in acute vs chronic inflammation. Heat-evoked and von Frey-evoked withdrawal reflexes and corresponding RVM neuronal activity were recorded in lightly anesthetized animals either during the first hour after complete Freund's adjuvant injection (acute) or 3 to 10 days later (chronic). Thermal and modest mechanical hyperalgesia during acute inflammation were associated with increases in the spontaneous activity of pain-facilitating ON-cells and suppression of pain-inhibiting OFF-cells. Acute hyperalgesia was reversed by RVM block, showing that the increased activity of RVM ON-cells is necessary for acute behavioral hypersensitivity. In chronic inflammation, thermal hyperalgesia had resolved but mechanical hyperalgesia had become pronounced. The spontaneous discharges of ON- and OFF-cells were not different from those in control subjects, but the mechanical response thresholds for both cell classes were reduced into the innocuous range. RVM block in the chronic condition worsened mechanical hyperalgesia. These studies identify distinct contributions of RVM ON- and OFF-cells to acute and chronic inflammatory hyperalgesia. During early immune-mediated inflammation, ON-cell spontaneous activity promotes hyperalgesia. After inflammation is established, the antinociceptive influence of OFF-cells is dominant, yet the lowered threshold for the OFF-cell pause allows behavioral responses to stimuli that would normally be considered innocuous. The efficacy of OFF-cells in counteracting sensitization of ascending transmission pathways could therefore be an important determining factor in development of chronic inflammatory pain. Copyright © 2013 International Association for the Study of Pain. Published by Elsevier B.V. All

  18. Water System Adaptations To Hydrological Changes: Module 4, Water Quality Response to Land-use and Precipitation Changes : Case Study of Ohio River Valley, USA

    Science.gov (United States)

    This course focuses on water system adaptation to short-term and long-term climate and hydrologic stressors that affect water availability, water quality, security, and resilience. The course is organized into 15 sequential modules. The lectures will be augmented by weekly assign...

  19. Water System Adaptation to Hydrological Changes: Module 2, Stormwater Management and Sewer Performance under Intense Storms: Case Study from Lawrence, Massachusetts, U.S.A.

    Science.gov (United States)

    This course focuses on water system adaptation to short-term and long-term climate and hydrologic stressors that affect water availability, water quality, security, and resilience. The course is organized into 15 sequential modules. The lectures will be augmented by weekly assign...

  20. Water System Adaptation To Hydrological Changes: Module 3, Consequences of Prolonged Drought on Urban Water System Resilience: Case Study from Las Vegas, Nevada, USA

    Science.gov (United States)

    This course focuses on water system adaptation to short-term and long-term climate and hydrologic stressors that affect water availability, water quality, security, and resilience. The course is organized into 15 sequential modules. The lectures will be augmented by weekly assign...

  1. Oxide-based High Temperature Thermoelectric Generators - Development of Integrated Design Technique and Construction of a Thermoelectric Module

    DEFF Research Database (Denmark)

    Wijesooriyage, Waruna Dissanayaka

    development. This thesis is focused on development and optimization of thermoelectric generator (TEG) design techniques for high temperature (> 700 °C) applications. Some of the main targets of this optimization process are to achieve higher volumetric power density (VPD), and reduce the cost-per-Watt. Oxide......In the field of energy management, thermoelectrics are niche candidates for electrical generator devices. For decades, scientists have been focused on thermoelectric (TE) material development. Thus TE module design techniques are still in relatively virgin state when comparing to the TE material...... challenges identified in this project. Thus, the proposed TEG optimizations should address this challenge in an appropriate manner. The work has established a new TEG optimization strategy based on the existing well-known TEG design technique Reduced Current Approach (RCA). This extended version of RCA...

  2. Modulation Technique for Four-Leg Voltage Source Inverter without a Look-Up Table

    DEFF Research Database (Denmark)

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

    2016-01-01

    of these classes itself has four kinds: (a) rising-edge aligned, (b) falling-edge aligned, (c) symmetrically aligned and (d) alternative sequence. In this study, implementation of the conventional 3D SVM technique in abc-coordinate for four-leg voltage source inverters is simplified, while it can be so easily...... 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...

  3. Water System Adaptation To Hydrological Changes: Module 5, Water Quality and Infrastructure Response to Rapid Urbanization: Adaptation Case Study in China

    Science.gov (United States)

    This course will introduce students to the fundamental principles of water system adaptation to hydrological changes, with emphasis on data analysis and interpretation, technical planning, and computational modeling. Starting with real-world scenarios and adaptation needs, the co...

  4. Adaptation Technique in the Translation of Literary Texts (as Exemplified in the Translation of French and English Literary Texts

    Directory of Open Access Journals (Sweden)

    Полина Сергеевна Тасенко

    2016-12-01

    Full Text Available This article describes some particularities of translation of literary texts from French and English into Russian as exemplified in the novel “The Lady of the Camellias” by A. Dumas and the novel “Wuthering Heights” by E. Brontë. The article examines in particular the use of the adaptation technique in order to confirm the hypothesis of the connection of this translation transformation with conveyance of the original's stylistic features. This transformation is applied in the translation of some phenomena and phrases in the original text that can barely be translated because of their national singularity, a significant time gap, or peculiarity for other culture bearers. The theoretical foundation for the article are literary style researches [Barkhudarov, 1975; Komissarov, 1990; Chaikovskij, 1997; Chukovskij, 2014; Baker, 2011], as well as researches in the field of the use of adaptation in the translation of literary texts [Alekseeva, 2004; Vlakhov, Florin, 1980; Shchetinkin, 1987; Clifford, Landers, 2001; Newmark, 1988]. The research methods used in the study are the following: relevant scientific literature analysis, statistical approach, comparative study of literary texts and their translations. A thorough analysis of the nature of adaptation enabled us to specify a range of translation transformations which allow adaptation to be applied in the reanslation of literary texts. According to the results of the research, the informative as well as the aesthetic function plays a very important role in the translation of literary texts.

  5. Optimization of multiple-module thermoelectric coolers using artificial-intelligence techniques

    Energy Technology Data Exchange (ETDEWEB)

    Chen, K. [University of Utah (United States). Dept. of Mechanical Engineering; Lin, G.T. [National Taiwan University of Science and Technology, Taipei (China). Dept. of Mechanical Engineering

    2002-07-01

    Genetic algorithm (GA) and simulated annealing (SA) methods were employed to optimize the current distribution of a cooler made up of a large number of thermoelectric (TE) modules. The TE modules were grouped into several clusters in the flow direction, and the electric currents supplied to different clusters were adjusted separately to achieve maximum energy efficiency or minimum refrigeration temperature for different,operating conditions and cooling requirements. Optimization results based on the design parameters of a large TE cooler showed considerable improvements in energy efficiency and refrigeration temperature when compared to the results of uniform current for the parallel-flow arrangement. On the other hand, results of the counter-flow arrangement showed only slight differences between uniform- and non-uniform-current optimizations. The optimization results of GA and SA were very close to each other. SA converged faster and was more computationally economical than GA for TE system optimization. (author)

  6. Percutaneous autonomic neural modulation: A novel technique to treat cardiac arrhythmia

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. [Cross-cultural Adaptation of the PedsQL Questionnaire Cancer Module, Version 3.0 for Use in Colombia].

    Science.gov (United States)

    Fontibón, Luis Fernando; Ardila, Sandra Liliana; Sánchez, Ricardo

    Quality of life is an important outcome in paediatric cancer patients. Its evaluation at different times during the clinical course of the disease is essential for clinical practice focused on the needs of the patients. There is not a specific assessment tool for this purpose in Colombia. To perform the cultural adaptation of the quality of life scale PedsQL (Paediatric Quality of Life) Cancer Module, Version 3.0 for use in Colombia. Permission for use of the scale was obtained and the algorithm steps of the Mapi Research Trust group were followed: Direct and independent translations of scale by two native Colombian Spanish speaking translators, obtaining a preliminary version from the translations. This was followed by a back translation by a native English speaking translator and a review of the process by the author of the scale, inclusion of suggestions, and implementation of the pilot study. Direct translations were similar in the instructions and response options; a consensus meeting in 8 of the 27 items was required to choose the best translation. The author made no suggestions and gave his endorsement to the implementation of the pilot, in which, 2 items were modified in order to improve their understanding. There is a Colombian Spanish version of the PedsQL questionnaire 3.0 Cancer Module, to be submitted for a validation study prior to its use in the assessment of quality of life in paediatric cancer patients. Copyright © 2016 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

  8. Vibrotactile stimulation of fast-adapting cutaneous afferents from the foot modulates proprioception at the ankle joint.

    Science.gov (United States)

    Mildren, Robyn L; Bent, Leah R

    2016-04-15

    It has previously been shown that cutaneous sensory input from across a broad region of skin can influence proprioception at joints of the hand. The present experiment tested whether cutaneous input from different skin regions across the foot can influence proprioception at the ankle joint. The ability to passively match ankle joint position (17° and 7° plantar flexion and 7° dorsiflexion) was measured while cutaneous vibration was applied to the sole (heel, distal metatarsals) or dorsum of the target foot. Vibration was applied at two different frequencies to preferentially activate Meissner's corpuscles (45 Hz, 80 μm) or Pacinian corpuscles (255 Hz, 10 μm) at amplitudes ∼3 dB above mean perceptual thresholds. Results indicated that cutaneous input from all skin regions across the foot could influence joint-matching error and variability, although the strongest effects were observed with heel vibration. Furthermore, the influence of cutaneous input from each region was modulated by joint angle; in general, vibration had a limited effect on matching in dorsiflexion compared with matching in plantar flexion. Unlike previous results in the upper limb, we found no evidence that Pacinian input exerted a stronger influence on proprioception compared with Meissner input. Findings from this study suggest that fast-adapting cutaneous input from the foot modulates proprioception at the ankle joint in a passive joint-matching task. These results indicate that there is interplay between tactile and proprioceptive signals originating from the foot and ankle. Copyright © 2016 the American Physiological Society.

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

    International Nuclear Information System (INIS)

    Giraud, P.; Giraud, P.; Morvan, E.; Djadi-Prat, J.; Rosenwald, J.C.; Carrere, M.O.

    2010-01-01

    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

  10. A game-theoretic architecture for visible watermarking system of ACOCOA (adaptive content and contrast aware technique

    Directory of Open Access Journals (Sweden)

    Tsai Min-Jen

    2011-01-01

    Full Text Available Abstract Digital watermarking techniques have been developed to protect the intellectual property. A digital watermarking system is basically judged based on two characteristics: security robustness and image quality. In order to obtain a robust visible watermarking in practice, we present a novel watermarking algorithm named adaptive content and contrast aware (ACOCOA, which considers the host image content and watermark texture. In addition, we propose a powerful security architecture against attacks for visible watermarking system which is based on game-theoretic approach that provides an equilibrium condition solution for the decision maker by studying the effects of transmission power on intensity and perceptual efficiency. The experimental results demonstrate that the feasibility of the proposed approach not only provides effectiveness and robustness for the watermarked images, but also allows the watermark encoder to obtain the best adaptive watermarking strategy under attacks.

  11. Multiscale Adapted Time-Splitting Technique for Nonisothermal Two-Phase Flow and Nanoparticles Transport in Heterogenous Porous Media

    KAUST Repository

    El-Amin, Mohamed F.

    2017-05-05

    This paper is devoted to study the problem of nonisothermal two-phase flow with nanoparticles transport in heterogenous porous media, numerically. For this purpose, we introduce a multiscale adapted time-splitting technique to simulate the problem under consideration. The mathematical model consists of equations of pressure, saturation, heat, nanoparticles concentration in the water–phase, deposited nanoparticles concentration on the pore–walls, and entrapped nanoparticles concentration in the pore–throats. We propose a multiscale time splitting IMplicit Pressure Explicit Saturation–IMplicit Temperature Concentration (IMPES-IMTC) scheme to solve the system of governing equations. The time step-size adaptation is achieved by satisfying the stability Courant–Friedrichs–Lewy (CFL<1) condition. Moreover, numerical test of a highly heterogeneous porous medium is provided and the water saturation, the temperature, the nanoparticles concentration, the deposited nanoparticles concentration, and the permeability are presented in graphs.

  12. Intensity modulated radiation therapy for squamous cell carcinoma of the vulva: Treatment technique and outcomes

    Directory of Open Access Journals (Sweden)

    Yuan James Rao, MD

    2017-04-01

    Conclusions: IMRT for vulvar cancer is associated with high rates of LRC in the postoperative setting and limited radiation-related toxicity. Durable LRC of disease after definitive IMRT remains challenging, and several refinements to our treatment technique are suggested.

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

    Directory of Open Access Journals (Sweden)

    Abubakar Muhammad Umaru

    2014-01-01

    Full Text Available 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 show that the proposed algorithm outperforms the hybrid and the FAT algorithms in terms of burst end-to-end delay, packet end-to-end delay, and packet loss ratio.

  14. Comparison of intensity-modulated radiotherapy, adaptive radiotherapy, proton radiotherapy, and adaptive proton radiotherapy for treatment of locally advanced head and neck cancer

    International Nuclear Information System (INIS)

    Simone, Charles B.; Ly, David; Dan, Tu D.; Ondos, John; Ning, Holly; Belard, Arnaud; O’Connell, John; Miller, Robert W.; Simone, Nicole L.

    2011-01-01

    Background and purpose: Various radiotherapy planning methods for locally advanced squamous cell carcinoma of the head and neck (SCCHN) have been proposed to decrease normal tissue toxicity. We compare IMRT, adaptive IMRT, proton therapy (IMPT), and adaptive IMPT for SCCHN. Materials and methods: Initial and re-simulation CT images from 10 consecutive patients with SCCHN were used to quantify dosimetric differences between photon and proton therapy. Contouring was performed on both CTs, and plans (n = 40 plans) and dose–volume histograms were generated. Results: The mean GTV volume decreased 53.4% with re-simulation. All plans provided comparable PTV coverage. Compared with IMRT, adaptive IMRT significantly reduced the maximum dose to the mandible (p = 0.020) and mean doses to the contralateral parotid gland (p = 0.049) and larynx (p = 0.049). Compared with IMRT and adaptive IMRT, IMPT significantly lowered the maximum doses to the spinal cord (p < 0.002 for both) and brainstem (p < 0.002 for both) and mean doses to the larynx (p < 0.002 for both) and ipsilateral (p = 0.004 IMRT, p = 0.050 adaptive) and contralateral (p < 0.002 IMRT, p = 0.010 adaptive) parotid glands. Adaptive IMPT significantly reduced doses to all critical structures compared with IMRT and adaptive IMRT and several critical structures compared with non-adaptive IMPT. Conclusions: Although adaptive IMRT reduced dose to several normal structures compared with standard IMRT, non-adaptive proton therapy had a more favorable dosimetric profile than IMRT or adaptive IMRT and may obviate the need for adaptive planning. Protons allowed significant sparing of the spinal cord, parotid glands, larynx, and brainstem and should be considered for SCCHN to decrease normal tissue toxicity while still providing optimal tumor coverage.

  15. Removing ECG Artifact from the Surface EMG Signal Using Adaptive Subtraction Technique

    Science.gov (United States)

    Abbaspour, S; Fallah, A

    2014-01-01

    Background: The electrocardiogram artifact is a major contamination in the electromyogram signals when electromyogram signal is recorded from upper trunk muscles and because of that the contaminated electromyogram is not useful. Objective: Removing electrocardiogram contamination from electromyogram signals. Methods: In this paper, the clean electromyogram signal, electrocardiogram artifact and electrocardiogram signal were recorded from leg muscles, the pectoralis major muscle of the left side and V4, respectively. After the pre-processing, contaminated electromyogram signal is simulated with a combination of clean electromyogram and electrocardiogram artifact. Then, contaminated electromyogram is cleaned using adaptive subtraction method. This method contains some steps; (1) QRS detection, (2) formation of electrocardiogram template by averaging the electrocardiogram complexes, (3) using low pass filter to remove undesirable artifacts, (4) subtraction. Results: Performance of our method is evaluated using qualitative criteria, power spectrum density and coherence and quantitative criteria signal to noise ratio, relative error and cross correlation. The result of signal to noise ratio, relative error and cross correlation is equal to 10.493, 0.04 and %97 respectively. Finally, there is a comparison between proposed method and some existing methods. Conclusion: The result indicates that adaptive subtraction method is somewhat effective to remove electrocardiogram artifact from contaminated electromyogram signal and has an acceptable result. PMID:25505766

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

    Science.gov (United States)

    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. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  17. Uncertainty quantification in reactor physics using adjoint/perturbation techniques and adaptive spectral methods

    NARCIS (Netherlands)

    Gilli, L.

    2013-01-01

    This thesis presents the development and the implementation of an uncertainty propagation algorithm based on the concept of spectral expansion. The first part of the thesis is dedicated to the study of uncertainty propagation methodologies and to the analysis of spectral techniques. The concepts

  18. Study of the osseointegration of dental implants placed with an adapted surgical technique

    NARCIS (Netherlands)

    Al-Marshood, M.M.; Junker, R.; Al-Rasheed, A.; Al Farraj Aldosari, A.; Jansen, J.A.; Anil, S.

    2011-01-01

    OBJECTIVE: To study the osseointegration of dental implants placed with a modified surgical technique in Beagle dogs and to compare it with the conventional method. MATERIALS AND METHODS: Dental implants were placed bilaterally in the mandible of Beagle dogs using the press-fit as well as undersized

  19. A Pulsed Coding Technique Based on Optical UWB Modulation for High Data Rate Low Power Wireless Implantable Biotelemetry

    Directory of Open Access Journals (Sweden)

    Andrea De Marcellis

    2016-10-01

    Full Text Available This paper reports on a pulsed coding technique based on optical Ultra-wideband (UWB modulation for wireless implantable biotelemetry systems allowing for high data rate link whilst enabling significant power reduction compared to the state-of-the-art. This optical data coding approach is suitable for emerging biomedical applications like transcutaneous neural wireless communication systems. The overall architecture implementing this optical modulation technique employs sub-nanosecond pulsed laser as the data transmitter and small sensitive area photodiode as the data receiver. Moreover, it includes coding and decoding digital systems, biasing and driving analogue circuits for laser pulse generation and photodiode signal conditioning. The complete system has been implemented on Field-Programmable Gate Array (FPGA and prototype Printed Circuit Board (PCB with discrete off-the-shelf components. By inserting a diffuser between the transmitter and the receiver to emulate skin/tissue, the system is capable to achieve a 128 Mbps data rate with a bit error rate less than 10−9 and an estimated total power consumption of about 5 mW corresponding to a power efficiency of 35.9 pJ/bit. These results could allow, for example, the transmission of an 800-channel neural recording interface sampled at 16 kHz with 10-bit resolution.

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

    Directory of Open Access Journals (Sweden)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

  2. Analysis of voltage modulation based active damping techniques for small DC-link drive system

    DEFF Research Database (Denmark)

    Wang, Dong; Lu, Kaiyuan; Rasmussen, Peter Omand

    2015-01-01

    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...

  3. A microcomputer-controlled modulation technique for the detection of transient species in UV photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Lonkhuyzen, H. van; Muller, H.G.; Lange, C.A. de

    1980-01-01

    A microcomputer-controlled modulation method is described to measure UV photoelectron spectra of transient species generated in a microwave discharge. Spectra at low and high microwave power levels are simultaneously recorded and afterwards linearly combined in order to remove parent compound signals. The method is applied to discharged oxygen where the transition O 2 + ( 2 PHIsub(u)) 2 ( 1 Δsub(g)) becomes visible without interference from the parent molecule O 2 ( 3 Σsub(g) - ), and to discharged sulphur dioxide where SO( 3 Σ - ) and S( 3 P) photoelectron spectra are obtained free from SO 2 bands. Finally the build-up of transient bands as a function of time is recorded. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Darboux, M.; Dinten, J.M.; Nicolas, E.

    1996-12-31

    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). 4 refs.

  5. Speckle noise reduction technique for Lidar echo signal based on self-adaptive pulse-matching independent component analysis

    Science.gov (United States)

    Xu, Fan; Wang, Jiaxing; Zhu, Daiyin; Tu, Qi

    2018-04-01

    Speckle noise has always been a particularly tricky problem in improving the ranging capability and accuracy of Lidar system especially in harsh environment. Currently, effective speckle de-noising techniques are extremely scarce and should be further developed. In this study, a speckle noise reduction technique has been proposed based on independent component analysis (ICA). Since normally few changes happen in the shape of laser pulse itself, the authors employed the laser source as a reference pulse and executed the ICA decomposition to find the optimal matching position. In order to achieve the self-adaptability of algorithm, local Mean Square Error (MSE) has been defined as an appropriate criterion for investigating the iteration results. The obtained experimental results demonstrated that the self-adaptive pulse-matching ICA (PM-ICA) method could effectively decrease the speckle noise and recover the useful Lidar echo signal component with high quality. Especially, the proposed method achieves 4 dB more improvement of signal-to-noise ratio (SNR) than a traditional homomorphic wavelet method.

  6. SU-F-T-503: Trajectory Modulated Arc Therapy of Intracranial Lesions: Development of a Standardized Path-Based Technique for Fully Dynamic Couch-Gantry Modulated Treatments

    Energy Technology Data Exchange (ETDEWEB)

    Khan, S; Chin, E; Xing, L; Hristov, D; Fahimian, B [Stanford University, Stanford, CA (United States); Otto, K [University of British Columbia, Victoria (Canada)

    2016-06-15

    Purpose: The integration of couch motion during arc delivery is necessitated to enable irradiation trajectories such as coronal arcs, and to enhance the geometrical sampling for dynamic deliveries to the highest extent. To enable such capability, a platform of Trajectory Modulated Arc Therapy (TMAT) is developed in conjunction with standardized noncollisional dynamic path-set for irradiation of intracranial lesions. Methods: A generalized path-set was constructed through the combination of sagittal arcs (45 degrees from the CAX), axial arcs, and coronal arcs produced through modulation of the dynamic rotation of couch. The standardized path was implemented in a contiguous manner enabling the formation of fully automated sub-trajectories to provide maximal geometrical convergence with minimal number of arcs. Progressive sampling technique is used for direct aperture optimization of the MLCs and the selection of couch positions across the control points. Dosimetry of the resulting plans was assessed relative to clinically delivered plans. Using the TrueBeam Developer Mode, plan deliverability was tested. Results: Treatment planning of TMAT sub-trajectories for central, anterior and posterior tumor sites with volumes ranging from 4.75cc to 107cc demonstrated radically reduced doses to the critical OARs when compared to the clinically treated VMAT. Specifically, percentage reduction in mean dose for critical organs such as brainstem, cochlea, and optic nerve are found to be as low as 74±15%, 50±26% and 74±30% respectively as compared to VMAT. Conformity Index, defined as the ratio of tumor volume (VPTV) and 100% dose volume (V(D100%)), was reduced up to 12% while the Gradient Index, defined as V(D100%)/V(D50%), was concurrently improved by up to 14%. Conclusion: An automated standardized trajectory with dynamically modulated couch-gantry arcs has been developed for intracranial radiotherapy. Through the incorporation of coronal arcs, it is demonstrated that

  7. Region-growing technique adapted to precise microcalcification characterization in mammography

    Science.gov (United States)

    Darboux, Michel; Dinten, Jean-Marc; Nicolas, Eric

    1996-11-01

    The early detection of breast cancer is essential for increasing the survival rate of the disease. Today, 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 microcalcifications. We present here a three-step method for detecting and characterizing these microcalcifications. We begin with the detection of potential candidates. The aim of this first step is to detect all the pixels that could be a microcalcification. Then we focus on our specific region growing technique which provides an accurate extraction of the shape of the region corresponding to each detected growing technique which provides an accurate extraction of the shape of the region corresponding to each detected seed. This second step is essential because microcalcifications shape is a very important feature for the diagnosis. It is then possible to determine precise parameters to characterize these microcalcifications. This three-step method has been evaluated on a set of images form the mammographic image analysis society database.

  8. Study of the osseointegration of dental implants placed with an adapted surgical technique.

    Science.gov (United States)

    Al-Marshood, Maysa M; Junker, Rudiger; Al-Rasheed, Abdulaziz; Al Farraj Aldosari, Abdullah; Jansen, John A; Anil, Sukumaran

    2011-07-01

    To study the osseointegration of dental implants placed with a modified surgical technique in Beagle dogs and to compare it with the conventional method. Dental implants were placed bilaterally in the mandible of Beagle dogs using the press-fit as well as undersized implant bed preparation technique. Micro computer tomography (micro-CT) and histometric methods were used to analyze the bone implant contact and bone volume (BV) around the implants. The bone-to-implant contact percentage (BIC: expressed as %), first BIC (1st BIC: expressed in mm), sulcus depth (SD: expressed in mm) and connective tissue thickness (CT: expressed in mm) were analyzed for both groups. The BIC percentage was significantly higher for the undersized installed implants (P=0.0118). Also, a significant difference existed between the undersized and press-fit installed implants for the first screw thread showing bone contact (P=0.0145). There were no significant differences in mucosal response (SD and CT) for both installation procedures. Also, no significant difference was found in the BV, as measured using micro-CT, between the implants placed with an undersized technique (59.3 ± 4.6) compared with the press-fit implants (56.6 ± 4.3). From the observations of the study, it can be concluded that an undersized implant bed can enhance the implant-bone response. © 2010 John Wiley & Sons A/S.

  9. Technique adaptation, strategic replanning, and team learning during implementation of MR-guided brachytherapy for cervical cancer.

    Science.gov (United States)

    Skliarenko, Julia; Carlone, Marco; Tanderup, Kari; Han, Kathy; Beiki-Ardakani, Akbar; Borg, Jette; Chan, Kitty; Croke, Jennifer; Rink, Alexandra; Simeonov, Anna; Ujaimi, Reem; Xie, Jason; Fyles, Anthony; Milosevic, Michael

    MR-guided brachytherapy (MRgBT) with interstitial needles is associated with improved outcomes in cervical cancer patients. However, there are implementation barriers, including magnetic resonance (MR) access, practitioner familiarity/comfort, and efficiency. This study explores a graded MRgBT implementation strategy that included the adaptive use of needles, strategic use of MR imaging/planning, and team learning. Twenty patients with cervical cancer were treated with high-dose-rate MRgBT (28 Gy in four fractions, two insertions, daily MR imaging/planning). A tandem/ring applicator alone was used for the first insertion in most patients. Needles were added for the second insertion based on evaluation of the initial dosimetry. An interdisciplinary expert team reviewed and discussed the MR images and treatment plans. Dosimetry-trigger technique adaptation with the addition of needles for the second insertion improved target coverage in all patients with suboptimal dosimetry initially without compromising organ-at-risk (OAR) sparing. Target and OAR planning objectives were achieved in most patients. There were small or no systematic differences in tumor or OAR dosimetry between imaging/planning once per insertion vs. daily and only small random variations. Peer review and discussion of images, contours, and plans promoted learning and process development. Technique adaptation based on the initial dosimetry is an efficient approach to implementing MRgBT while gaining comfort with the use of needles. MR imaging and planning once per insertion is safe in most patients as long as applicator shifts, and large anatomical changes are excluded. Team learning is essential to building individual and programmatic competencies. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  10. Applying modern psychometric techniques to melodic discrimination testing: Item response theory, computerised adaptive testing, and automatic item generation.

    Science.gov (United States)

    Harrison, Peter M C; Collins, Tom; Müllensiefen, Daniel

    2017-06-15

    Modern psychometric theory provides many useful tools for ability testing, such as item response theory, computerised adaptive testing, and automatic item generation. However, these techniques have yet to be integrated into mainstream psychological practice. This is unfortunate, because modern psychometric techniques can bring many benefits, including sophisticated reliability measures, improved construct validity, avoidance of exposure effects, and improved efficiency. In the present research we therefore use these techniques to develop a new test of a well-studied psychological capacity: melodic discrimination, the ability to detect differences between melodies. We calibrate and validate this test in a series of studies. Studies 1 and 2 respectively calibrate and validate an initial test version, while Studies 3 and 4 calibrate and validate an updated test version incorporating additional easy items. The results support the new test's viability, with evidence for strong reliability and construct validity. We discuss how these modern psychometric techniques may also be profitably applied to other areas of music psychology and psychological science in general.

  11. AOTF-based optical system of a microscope module for multispectral imaging techniques

    Science.gov (United States)

    Polschikova, Olga; Machikhin, Alexander; Batshev, Vladislav; Ramazanova, Alina; Belov, Artyom; Pozhar, Vitold

    2017-12-01

    Multi-spectral imaging techniques are widely used in microscopy for many applications. One of the most widespread spectral elements for this purpose is an imaging acousto-optic tunable filter (AOTF). AOTF-based contrast visualization is especially effective when used together with other imaging techniques. Simultaneous utilization of two or more imagers requires optical coupling to provide point-to-point matching of the obtained images. Small linear and angular aperture of AOTF additionally hampers the development of multi-sensor imaging systems for microscopy. In this paper, we present a compact optical system which allows to integrate AOTF-based spectral imager into the schemes of conventional microscopes and provide high-quality spectral image of the same scale as in another, for example, wideband channel. The effectiveness of the proposed approach is demonstrated experimentally.

  12. Cosine Modulated and Offset QAM Filter Bank Multicarrier Techniques: A Continuous-Time Prospect

    Directory of Open Access Journals (Sweden)

    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.

  13. Cosine Modulated and Offset QAM Filter Bank Multicarrier Techniques: A Continuous-Time Prospect

    Directory of Open Access Journals (Sweden)

    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.

  14. Adapting content-based image retrieval techniques for the semantic annotation of medical images.

    Science.gov (United States)

    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Comparative Analysis of Linear and Nonlinear Pattern Synthesis of Hemispherical Antenna Array Using Adaptive Evolutionary Techniques

    Directory of Open Access Journals (Sweden)

    K. R. Subhashini

    2014-01-01

    synthesis is termed as the variation in the element excitation amplitude and nonlinear synthesis is process of variation in element angular position. Both ADE and AFA are a high-performance stochastic evolutionary algorithm used to solve N-dimensional problems. These methods are used to determine a set of parameters of antenna elements that provide the desired radiation pattern. The effectiveness of the algorithms for the design of conformal antenna array is shown by means of numerical results. Comparison with other methods is made whenever possible. The results reveal that nonlinear synthesis, aided by the discussed techniques, provides considerable enhancements compared to linear synthesis.

  16. Analysis of Adaptive Fuzzy Technique for Multiple Crack Diagnosis of Faulty Beam Using Vibration Signatures

    Directory of Open Access Journals (Sweden)

    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.

  17. The pursuit of balance: An overview of covariate-adaptive randomization techniques in clinical trials.

    Science.gov (United States)

    Lin, Yunzhi; Zhu, Ming; Su, Zheng

    2015-11-01

    Randomization is fundamental to the design and conduct of clinical trials. Simple randomization ensures independence among subject treatment assignments and prevents potential selection biases, yet it does not guarantee balance in covariate distributions across treatment groups. Ensuring balance in important prognostic covariates across treatment groups is desirable for many reasons. A broad class of randomization methods for achieving balance are reviewed in this paper; these include block randomization, stratified randomization, minimization, and dynamic hierarchical randomization. Practical considerations arising from experience with using the techniques are described. A review of randomization methods used in practice in recent randomized clinical trials is also provided. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Robust and adaptive techniques for numerical simulation of nonlinear partial differential equations of fractional order

    Science.gov (United States)

    Owolabi, Kolade M.

    2017-03-01

    In this paper, some nonlinear space-fractional order reaction-diffusion equations (SFORDE) on a finite but large spatial domain x ∈ [0, L], x = x(x , y , z) and t ∈ [0, T] are considered. Also in this work, the standard reaction-diffusion system with boundary conditions is generalized by replacing the second-order spatial derivatives with Riemann-Liouville space-fractional derivatives of order α, for 0 Fourier spectral method is introduced as a better alternative to existing low order schemes for the integration of fractional in space reaction-diffusion problems in conjunction with an adaptive exponential time differencing method, and solve a range of one-, two- and three-components SFORDE numerically to obtain patterns in one- and two-dimensions with a straight forward extension to three spatial dimensions in a sub-diffusive (0 reaction-diffusion case. With application to models in biology and physics, different spatiotemporal dynamics are observed and displayed.

  19. Surface dose measurement with Gafchromic EBT3 film for intensity modulated radiotherapy technique

    Science.gov (United States)

    Akbas, Ugur; Kesen, Nazmiye Donmez; Koksal, Canan; Okutan, Murat; Demir, Bayram; Becerir, Hatice Bilge

    2017-09-01

    Accurate dose measurement in the buildup region is extremely difficult. Studies have reported that treatment planning systems (TPS) cannot calculate surface dose accurately. The aim of the study was to compare the film measurements and TPS calculations for surface dose in head and neck cancer treatment using intensity modulated radiation therapy (IMRT). IMRT plans were generated for 5 head and neck cancer patients by using Varian Eclipse TPS. Quality assurance (QA) plans of these IMRT plans were created on rando phantoms for surface dose measurements. EBT3 films were cut in size of 2.5 x 2.5 cm2 and placed on the left side, right side and the center of larynx and then the films were irradiated with 6 MV photon beams. The measured doses were compared with TPS. The results of TPS calculations were found to be lower compared to the EBT3 film measurements at all selected points. The lack of surface dose calculation in TPS should be considered while evaluating the radiotherapy plans.

  20. Vapor pressure data for fatty acids obtained using an adaptation of the DSC technique

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Water System Adaptation To Hydrological Changes: Module 9, Water System Resilience and Security under Hydrologic Variability and Uncertainty

    Science.gov (United States)

    This course will introduce students to the fundamental principles of water system adaptation to hydrological changes, with emphasis on data analysis and interpretation, technical planning, and computational modeling. Starting with real-world scenarios and adaptation needs, the co...

  2. Developing a Virtual Teach-To-Goal™ Inhaler Technique Learning Module: A Mixed Methods Approach.

    Science.gov (United States)

    Wu, Meng; Woodrick, Nicole M; Arora, Vineet M; Farnan, Jeanne M; Press, Valerie G

    Most hospitalized patients with asthma or chronic obstructive pulmonary disease misuse respiratory inhalers. An in-person educational strategy, teach-to-goal (TTG), improves inpatients' inhaler technique. To develop an effective, portable education intervention that remains accessible to hospitalized patients postdischarge for reinforcement of proper inhaler technique. A mixed methods approach at an urban academic hospital was used to iteratively develop, modify, and test a virtual teach-to-goal ™ (V-TTG ™ ) educational intervention using patient end-user feedback. A survey examined access and willingness to use technology for self-management education. Focus groups evaluated patients' feedback on access, functionality, and quality of V-TTG ™ . Forty-eight participants completed the survey, with most reporting having Internet access; 77% used the Internet at home and 82% used the Internet at least once every few weeks. More than 80% reported that they were somewhat or very likely to use V-TTG ™ to gain skills to improve their health. Most participants reported smartphone access (73%); half owned laptop computers (52%). Participants with asthma versus chronic obstructive pulmonary disease were more likely to own a smartphone, have a data plan, and have daily Internet use (P platform and delivery, Internet access, and technological literacy; functionality-usefulness, content, and teaching strategy; and quality-clarity, ease of use, length, and likability. V-TTG ™ is a promising educational tool for improving patients' inhaler technique, iteratively developed and refined with patient input. Patients in our urban, academic hospital overwhelmingly reported access to platforms and willingness to use V-TTG ™ for health education. Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  3. Adaptation of proteomic techniques for the identification and characterization of protein species from murine heart.

    Science.gov (United States)

    Schwab, Karima; Neumann, Boris; Scheler, Christian; Jungblut, Peter R; Theuring, Franz

    2011-07-01

    Disturbed energy metabolism with impaired fatty acid oxidation, ATP synthesis and changing levels of contractile proteins has been observed during the development and manifestation of cardiovascular diseases, with the latter showing sexual differences in terms of onset, manifestation and progress. Estrogenic compounds, such as estrogens and phytoestrogens, are known to exert beneficial effects on several cardiovascular parameters. However, global studies implying the normal, non-failing myocardium are rare. Thus, identifying and characterizing protein patterns involved in the maintenance of normal heart physiology at the protein species level will help understanding disease conditions. In this study, we performed an adapted 2-DE/MS approach in order to identify and characterize post-translational modified and truncated protein species from murine heart. Female and male animals of different age were receiving the phytoestrogen genistein and comparative analyses were performed to identify sex and genistein treatment-related effects. Selected 2-DE spots that exposed varying abundance between animal groups and identified as identical proteins were subject to multi-protease cleavage to generate an elevated sequence coverage enabling characterization of post-translational modifications and truncation loci via high-resolution MS. Several truncated, phosphorylated and acetylated species were identified for mitochondrial ATP synthase, malate dehydrogenase and trifunctional enzyme subunit alpha. However, confirmation of several of these modifications by manual spectra interpretation failed. Thus, our results warrant caution for the blind trust in software output. For the regulatory light chain of myosin, we identified an N-terminal processed species, which so far has been related to ischemic conditions only. We tried to unravel the information content of protein species separated by high-resolution 2-DE as an alternative to high-throughput proteomics, which mainly is

  4. Physical Forces Modulate Oxidative Status and Stress Defense Meditated Metabolic Adaptation of Yeast Colonies: Spaceflight and Microgravity Simulations

    Science.gov (United States)

    Hammond, Timothy G.; Allen, Patricia L.; Gunter, Margaret A.; Chiang, Jennifer; Giaever, Guri; Nislow, Corey; Birdsall, Holly H.

    2017-12-01

    Baker's yeast (Saccharomyces cerevisiae) has broad genetic homology to human cells. Although typically grown as 1-2mm diameter colonies under certain conditions yeast can form very large (10 + mm in diameter) or `giant' colonies on agar. Giant yeast colonies have been used to study diverse biomedical processes such as cell survival, aging, and the response to cancer pharmacogenomics. Such colonies evolve dynamically into complex stratified structures that respond differentially to environmental cues. Ammonia production, gravity driven ammonia convection, and shear defense responses are key differentiation signals for cell death and reactive oxygen system pathways in these colonies. The response to these signals can be modulated by experimental interventions such as agar composition, gene deletion and application of pharmaceuticals. In this study we used physical factors including colony rotation and microgravity to modify ammonia convection and shear stress as environmental cues and observed differences in the responses of both ammonia dependent and stress response dependent pathways We found that the effects of random positioning are distinct from rotation. Furthermore, both true and simulated microgravity exacerbated both cellular redox responses and apoptosis. These changes were largely shear-response dependent but each model had a unique response signature as measured by shear stress genes and the promoter set which regulates them These physical techniques permitted a graded manipulation of both convection and ammonia signaling and are primed to substantially contribute to our understanding of the mechanisms of drug action, cell aging, and colony differentiation.

  5. Neutron spectral modulation as a new thermal neutron scattering technique. Pt. 1

    International Nuclear Information System (INIS)

    Ito, Y.; Nishi, M.; Motoya, K.

    1982-01-01

    A thermal neutron scattering technique is presented based on a new idea of labelling each neutron in its spectral position as well as in time through the scattering process. The method makes possible the simultaneous determination of both the accurate dispersion relation and its broadening by utilizing the resolution cancellation property of zero-crossing points in the cross-correlated time spectrum together with the Fourier transform scheme of the neutron spin echo without resorting to the echoing. The channel Fourier transform applied to the present method also makes possible the determination of the accurate direct energy scan profile of the scattering function with a rather broad incident neutron wavelength distribution. Therefore the intensity sacrifice for attaining high accurarcy is minimized. The technique is used with either a polarized or unpolarized beam at the sample position with no precautions against beam depolarization at the sample for the latter case. Relative time accurarcy of the order of 10 -3 to 10 -4 may be obtained for the general dispersion relation and for the quasi-elastic energy transfers using correspondingly the relative incident neutron wavelength spread of 10 to 1% around an incident neutron energy of a few meV. (orig.)

  6. Unambiguous Multipath Mitigation Technique for BOC(n,n and MBOC-Modulated GNSS Signals

    Directory of Open Access Journals (Sweden)

    Khaled Rouabah

    2012-01-01

    Full Text Available We propose an efficient scheme for side peaks cancelation and multipath (MP mitigation in binary offset carrier (n,n (BOC(n,n and multiplexed BOC (MBOC modulated signals. The proposed scheme reduces significantly the band of variation of MP errors in global navigation satellite system (GNSS. It consists of two versions. The first one is based on the use of maximum likelihood estimator (MLE of MP signals and reference correlation functions (CFs like that of pseudorandom noise (PRN code without BOC subcarrier. In the second version, the former (MLE is used with the reference BOC(n,n or MBOC CFs. Unlike traditional BOC(n,n and MBOC, that have CFs containing multiple peaks leading to potential tracking ambiguities, our proposed scheme does not contain any side peaks. In addition, all the MP signals with medium and long delays have no effect on the estimation of the pseudorange. On the other hand, all the methods proposed for mitigating MP in no-BOC scheme are practical for our scheme due to its CF which is similar to that of the PRN code. The computer simulation results show that the proposed scheme has superior performances in the reduction of the errors produced in the process of the delay estimation of line of sight (LOS and caused by MP propagation. In fact, the performances of the proposed scheme are better with regard to that of the traditional BOC(n,n and MBOC. Moreover, in the presence of noise, our proposed scheme keeps better performances than the common side peaks cancelation methods.

  7. Resolution enhancement for ultrasonic echographic technique in non destructive testing with an adaptive deconvolution method

    International Nuclear Information System (INIS)

    Vivet, L.

    1989-01-01

    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 [fr

  8. Evaluation of two tomotherapy-based techniques for the delivery of whole-breast intensity-modulated radiation therapy

    International Nuclear Information System (INIS)

    Gonzalez, Victor J.; Buchholz, Daniel J.; Langen, Katja M.; Olivera, Gustavo H.; Chauhan, Bhavin; Meeks, Sanford L.; Ruchala, Kenneth J.; Haimerl, Jason; Lu Weiguo; Kupelian, Patrick A.

    2006-01-01

    Purpose: To evaluate two different techniques for whole-breast treatments delivered using the Hi-ART II tomotherapy device. Methods and Materials: Tomotherapy uses the standard rotational helical delivery. Topotherapy uses a stationary gantry while delivering intensity-modulated treatments. CT scans from 5 breast cancer patients were used. The prescription dose was 50.4 Gy. Results: On average, 99% of the target volume received 95% of prescribed dose with either technique. If treatment times are restricted to less than 9 min, the average percentage ipsilateral lung receiving ≥20 Gy was 22% for tomotherapy vs. 10% for topotherapy. The ipsilateral lung receiving ≥50.4 Gy was 4 cc for tomotherapy vs. 27 cc for topotherapy. The percentage of left ventricle receiving ≥30 Gy was 14% with tomotherapy vs. 4% for topotherapy. The average doses to the contralateral breast and lung were 0.6 and 0.8 Gy, respectively, for tomotherapy vs. 0.4 and 0.3 Gy for topotherapy. Conclusions: Tomotherapy provides improved target dose homogeneity and conformality over topotherapy. If delivery times are restricted, topotherapy reduces the amount of heart and ipsilateral lung volumes receiving low doses. For whole-breast treatments, topotherapy is an efficient technique that achieves adequate target uniformity while maintaining low doses to sensitive structures

  9. A miniaturized compact open-loop RFOG with demodulation signal compensation technique to suppress intensity modulation noise

    Science.gov (United States)

    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.

  10. Phase velocity estimation technique based on adaptive beamforming for ultrasonic guided waves propagating along cortical long bones

    Science.gov (United States)

    Okumura, Shigeaki; Nguyen, Vu-Hieu; Taki, Hirofumi; Haïat, Guillaume; Naili, Salah; Sato, Toru

    2017-07-01

    The axial transmission technique, which is used to estimate the phase velocity of an ultrasonic guided wave propagating along cortical bone is a promising tool for bone quality assessment. Lamb waves are ultrasonic guided waves that consist of multiple modes. The number of existing modes and the signal-to-noise ratio required for phase velocity estimation depend on the frequency of the signal. Hence, we employ an adaptive beamforming technique with spatial averaging to control signal-to-noise ratio and resolution by situating subarrays within the full array. Because the determination of the optimal size for spatial averaging is difficult, we propose a new algorithm that does not require a specific size with a new false-phase-velocity rejection technique. Using a 2.0-mm-thick copper plate, the proposed method accurately estimates phase velocity with fitting errors of 0.26 and 1.3%, as shown by simulation and experimental results, respectively. The measurement frequency ranges are more than twice wider than those measured by the conventional method.

  11. Measuring food insecurity and hunger in Peru: a qualitative and quantitative analysis of an adapted version of the USDA's Food Insecurity and Hunger Module.

    Science.gov (United States)

    Vargas, Silvana; Penny, Mary E

    2010-10-01

    To adapt a scale to measure perceptions on food insecurity and hunger among households in urban and rural communities in Peru. Qualitative and quantitative methodology including consultation with regional experts, key informant interviews and focus groups. A field survey trial was conducted in urban and rural communities using an adapted version of the US Department of Agriculture (USDA) Food Insecurity and Hunger Module (FIHM). Five communities in three regions in Peru - Lima (coast), Ayacucho (Andean highlands) and San Martín (Amazon basin). The qualitative component included forty intentionally selected people (fourteen key informants and twenty-six focus group participants). For the quantitative component 300 households that complied with selection criteria (poor or non-poor with at least one child below 12 years of age) were surveyed. Qualitative research showed that concern about food availability and access was common among the three regions but its main cause varied across them. Participation in food aid programmes was a strategy to face constraints in food access. Mothers' perceptions on the importance of balanced meals varied across households from different regions. Quantitative results showed robust findings for the reliability of the adapted FIHM's fifteen-item scale (r > 0.863). In addition, descriptive results confirmed parallelism of item responses in the scale for variables such as farm ownership, family size and use of Communal Kitchens. This mixed-method study allowed us to adapt the USDA module to assess food insecurity in Peru.

  12. Measurement of Relaxation Time of Excess Carriers in Si and CIGS Solar Cells by Modulated Electroluminescence Technique

    Energy Technology Data Exchange (ETDEWEB)

    Khatavkar, Sanchit [Indian Institute of Technology Bombay, Powai Mumbai 400076 India; Sanjivani College of Engineering, Kopargaon 423601 India; Muniappan, Kulasekaran [Indian Institute of Technology Bombay, Powai Mumbai 400076 India; Kannan, Chinna V. [MoserBaer Photovoltaic Pvt. Ltd., U.P. Greater Noida 201306 India; Kumar, Vijay [MoserBaer Photovoltaic Pvt. Ltd., U.P. Greater Noida 201306 India; Narsimhan, Krishnamachari L. [Indian Institute of Technology Bombay, Powai Mumbai 400076 India; Nair, Pradeep R. [Indian Institute of Technology Bombay, Powai Mumbai 400076 India; Vasi, Juzer M. [Indian Institute of Technology Bombay, Powai Mumbai 400076 India; Contreras, Miguel A. [National Renewable Energy Laboratory, Golden CO 80401 USA; van Hest, Maikel F. A. M. [National Renewable Energy Laboratory, Golden CO 80401 USA; Arora, Brij M. [Indian Institute of Technology Bombay, Powai Mumbai 400076 India; Indian Institute of Technology Goa, Farmagudi Ponda 403401 India

    2017-11-10

    Excess carrier lifetime plays a crucial role in determining the efficiency of solar cells. In this paper, we use the frequency dependence of inphase and quadrature components of modulated electroluminescence (MEL) to measure the relaxation time (decay) of excess carriers. The advantage of the MEL technique is that the relaxation time is obtained directly from the angular frequency at which the quadrature component peaks. It does not need knowledge of the material parameters like mobility, etc., and can be used for any finished solar cells which have detectable light emission. The experiment is easy to perform with standard electrical equipment. For silicon solar cells, the relaxation time is dominated by recombination and hence, the relaxation time is indeed the excess carrier lifetime. In contrast, for the CIGS solar cells investigated here, the relaxation time is dominated by trapping and emission from shallow minority carrier traps.

  13. Rapid and noncontact photoacoustic tomography imaging system using an interferometer with high-speed phase modulation technique

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. On-line monitoring of solar cell module production by ellipsometry technique

    International Nuclear Information System (INIS)

    Fried, M.

    2014-01-01

    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, CuInGaSe 2 , 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

  15. Enhancement of the production of L-glutaminase, an anticancer enzyme, from Aeromonas veronii by adaptive and induced mutation techniques.

    Directory of Open Access Journals (Sweden)

    S Aravinth Vijay Jesuraj

    Full Text Available Microbial anti-cancer enzymes have been proven to be effective and economical agents for cancer treatment. Aeromonas veronii has been identified as a microorganism with the potential to produce L-glutaminase, an anticancer agent effective against acute lymphocytic leukaemia. In this study, a selective medium of Aeromonas veronii was used to culture the microorganism. Strain improvement was done by adaptive and induced mutational techniques. A selective minimal agar media was incorporated for the growth of the strain which further supports adaptive mutation. Strains were also UV-irradiated and successively treated with N-methyl-N'-nitro-N-nitrosoguanidine to find a resilient strain capable of producing L-glutaminase efficiently. The Plackett-Burman design and central composite designs were used to screen and optimize additional carbon and nitrogen sources. Adaptive mutation resulted in promising yield improvements compared to native strain (P<0.001. The mean yield of 30 treated colonies from the induced mutation was significantly increased compared to the non-induced strain (P< 0.001. The economically feasible statistical designs were found to reinforce each other in order to maximize the yield of the enzyme. The interactions of nutrient factors were understood from the 3D response surface plots. The model was found to be a perfect fit in terms of maximizing enzyme yield, with the productivity improving at every stage to a fourfold output of enzyme (591.11 ±7.97 IU/mL compared to the native strain (135±3.51 IU/mL.

  16. Breathing adapted radiotherapy for breast cancer: comparison of free breathing gating with the breath-hold technique

    DEFF Research Database (Denmark)

    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...

  17. Sorting of pistachio nuts using image processing techniques and an adaptive neural-fuzzy inference system

    Directory of Open Access Journals (Sweden)

    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.

  18. Integration of adaptive guided filtering, deep feature learning, and edge-detection techniques for hyperspectral image classification

    Science.gov (United States)

    Wan, Xiaoqing; Zhao, Chunhui; Gao, Bing

    2017-11-01

    The integration of an edge-preserving filtering technique in the classification of a hyperspectral image (HSI) has been proven effective in enhancing classification performance. This paper proposes an ensemble strategy for HSI classification using an edge-preserving filter along with a deep learning model and edge detection. First, an adaptive guided filter is applied to the original HSI to reduce the noise in degraded images and to extract powerful spectral-spatial features. Second, the extracted features are fed as input to a stacked sparse autoencoder to adaptively exploit more invariant and deep feature representations; then, a random forest classifier is applied to fine-tune the entire pretrained network and determine the classification output. Third, a Prewitt compass operator is further performed on the HSI to extract the edges of the first principal component after dimension reduction. Moreover, the regional growth rule is applied to the resulting edge logical image to determine the local region for each unlabeled pixel. Finally, the categories of the corresponding neighborhood samples are determined in the original classification map; then, the major voting mechanism is implemented to generate the final output. Extensive experiments proved that the proposed method achieves competitive performance compared with several traditional approaches.

  19. Linearized Flux Evolution (LiFE): A technique for rapidly adapting fluxes from full-physics radiative transfer models

    Science.gov (United States)

    Robinson, Tyler D.; Crisp, David

    2018-05-01

    Solar and thermal radiation are critical aspects of planetary climate, with gradients in radiative energy fluxes driving heating and cooling. Climate models require that radiative transfer tools be versatile, computationally efficient, and accurate. Here, we describe a technique that uses an accurate full-physics radiative transfer model to generate a set of atmospheric radiative quantities which can be used to linearly adapt radiative flux profiles to changes in the atmospheric and surface state-the Linearized Flux Evolution (LiFE) approach. These radiative quantities describe how each model layer in a plane-parallel atmosphere reflects and transmits light, as well as how the layer generates diffuse radiation by thermal emission and by scattering light from the direct solar beam. By computing derivatives of these layer radiative properties with respect to dynamic elements of the atmospheric state, we can then efficiently adapt the flux profiles computed by the full-physics model to new atmospheric states. We validate the LiFE approach, and then apply this approach to Mars, Earth, and Venus, demonstrating the information contained in the layer radiative properties and their derivatives, as well as how the LiFE approach can be used to determine the thermal structure of radiative and radiative-convective equilibrium states in one-dimensional atmospheric models.

  20. Diagnostic radiography students' perceptions of formative peer assessment within a radiographic technique module.

    Science.gov (United States)

    Elshami, W; Abdalla, M E

    2017-02-01

    Assessment is a central part of student learning. Student involvement in peer assessment leads to significant improvement in students' performance, supports students' learning, promotes the development of evaluation skills and encourages reflection. The aim of this study is to assess perceptions of the Formative Peer Assessment (FPA) initiative within a higher education setting for undergraduate radiography students. Qualitative action research was conducted. Students were allowed to anonymously assess each other's assignments using a standardized evaluation sheet that they had been trained to use. Participants' perceptions were assessed through focus group discussion. The findings showed that students' experiences with peer assessment were positive. Students acknowledged that they received valuable feedback and learned from assessing their peers. Students recommended the need for training and suggested using more than one evaluator. The FPA initiative in the study institution believed to be succeed as the students had a positive experience with the FPA. Students learnt from PA and from self-assessment. Implementation of PA will promote reflection and critical thinking and problem solving skills, that are important traits in radiography graduate profile as in radiography clinical practice the professional require to modify imaging techniques and critique images to ensure the quality of care. Copyright © 2016 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.

  1. PhoU Allows Rapid Adaptation to High Phosphate Concentrations by Modulating PstSCAB Transport Rate in Sinorhizobium meliloti.

    Science.gov (United States)

    diCenzo, George C; Sharthiya, Harsh; Nanda, Anish; Zamani, Maryam; Finan, Turlough M

    2017-09-15

    Maintenance of cellular phosphate homeostasis is essential for cellular life. The PhoU protein has emerged as a key regulator of this process in bacteria, and it is suggested to modulate phosphate import by PstSCAB and control activation of the phosphate limitation response by the PhoR-PhoB two-component system. However, a proper understanding of PhoU has remained elusive due to numerous complications of mutating phoU , including loss of viability and the genetic instability of the mutants. Here, we developed two sets of strains of Sinorhizobium meliloti that overcame these limitations and allowed a more detailed and comprehensive analysis of the biological and molecular activities of PhoU. The data showed that phoU cannot be deleted in the presence of phosphate unless PstSCAB is inactivated also. However, phoU deletions were readily recovered in phosphate-free media, and characterization of these mutants revealed that addition of phosphate to the environment resulted in toxic levels of PstSCAB-mediated phosphate accumulation. Phosphate uptake experiments indicated that PhoU significantly decreased the PstSCAB transport rate specifically in phosphate-replete cells but not in phosphate-starved cells and that PhoU could rapidly respond to elevated environmental phosphate concentrations and decrease the PstSCAB transport rate. Site-directed mutagenesis results suggested that the ability of PhoU to respond to phosphate levels was independent of the conformation of the PstSCAB transporter. Additionally, PhoU-PhoU and PhoU-PhoR interactions were detected using a bacterial two-hybrid screen. We propose that PhoU modulates PstSCAB and PhoR-PhoB in response to local, internal fluctuations in phosphate concentrations resulting from PstSCAB-mediated phosphate import. IMPORTANCE Correct maintenance of cellular phosphate homeostasis is critical in all kingdoms of life and in bacteria involves the PhoU protein. This work provides novel insights into the role of the Sinorhizobium

  2. Diagnostic radiography students' perceptions of formative peer assessment within a radiographic technique module

    International Nuclear Information System (INIS)

    Elshami, W.; Abdalla, M.E.

    2017-01-01

    Introduction: Assessment is a central part of student learning. Student involvement in peer assessment leads to significant improvement in students' performance, supports students' learning, promotes the development of evaluation skills and encourages reflection. Aim: The aim of this study is to assess perceptions of the Formative Peer Assessment (FPA) initiative within a higher education setting for undergraduate radiography students. Methods: Qualitative action research was conducted. Students were allowed to anonymously assess each other's assignments using a standardized evaluation sheet that they had been trained to use. Participants' perceptions were assessed through focus group discussion. Results: The findings showed that students' experiences with peer assessment were positive. Students acknowledged that they received valuable feedback and learned from assessing their peers. Students recommended the need for training and suggested using more than one evaluator. Conclusion: The FPA initiative in the study institution believed to be succeed as the students had a positive experience with the FPA. Students learnt from PA and from self-assessment. Implementation of PA will promote reflection and critical thinking and problem solving skills, that are important traits in radiography graduate profile as in radiography clinical practice the professional require to modify imaging techniques and critique images to ensure the quality of care. - Highlights: • Participants had a positive experience with the Formative Peer Assessment (FPA). • Students believed that the FPA had a positive impact on their learning. • FPA was time-consuming but benefits outweigh the extra time commitment. • Comprehensive training and detailed grading rubric are recommended to improve FPA.

  3. Weld-bonding: a very well adapted joining technique to decrease the weight of steel structures; Le soudo-collage: une technique d'assemblage performante pour alleger les structures en acier

    Energy Technology Data Exchange (ETDEWEB)

    Charbonnet, Ph.; Clad, A.; Di Fant-Jaeckels, H.; Thirion, J.L. [Usinor RD, 92 - Puteaux (France)

    2000-04-01

    The association of spot welding and adhesive bonding, named weld-bonding, is a steel joining technique which increasingly interests car manufacturers. Nevertheless, weld-bonding is not at present used extensively by them due to a lack of data related to the performance of this technique. Studies carried out by Usinor have succeeded in demonstrating that weld-bonding is a very well adapted joining technique to decrease the weight of steel structures. (author)

  4. Professional Teacher Education Module Series. Direct Students in Applying Problem-Solving Techniques, Module C-8 of Category C--Instructional Execution.

    Science.gov (United States)

    Ohio State Univ., Columbus. National Center for Research in Vocational Education.

    This eighth in a series of twenty-nine learning modules on instructional execution is designed to give secondary and postsecondary vocational teachers the background knowledge and experience needed to use problem solving as an instructional method in the classroom and laboratory. The terminal objective for the module is to direct students in…

  5. Comparison of digital signal-signal beat interference compensation techniques in direct-detection subcarrier modulation systems.

    Science.gov (United States)

    Li, Zhe; Erkilinc, M Sezer; Galdino, Lidia; Shi, Kai; Thomsen, Benn C; Bayvel, Polina; Killey, Robert I

    2016-12-12

    Single-polarization direct-detection transceivers may offer advantages compared to digital coherent technology for some metro, back-haul, access and inter-data center applications since they offer low-cost and complexity solutions. However, a direct-detection receiver introduces nonlinearity upon photo detection, since it is a square-law device, which results in signal distortion due to signal-signal beat interference (SSBI). Consequently, it is desirable to develop effective and low-cost SSBI compensation techniques to improve the performance of such transceivers. In this paper, we compare the performance of a number of recently proposed digital signal processing-based SSBI compensation schemes, including the use of single- and two-stage linearization filters, an iterative linearization filter and a SSBI estimation and cancellation technique. Their performance is assessed experimentally using a 7 × 25 Gb/s wavelength division multiplexed (WDM) single-sideband 16-QAM Nyquist-subcarrier modulation system operating at a net information spectral density of 2.3 (b/s)/Hz.

  6. SU-F-T-446: Improving Craniospinal Irradiation Technique Using Volumetric Modulated Arc Therapy (VMAT) Planning and Its Dosimetric Verification

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X; Tejani, M; Jiang, X; Elder, E; Dhabaan, A [Emory University, Atlanta, GA (United States)

    2016-06-15

    Purpose: The purpose of this study is to investigate a volumetric modulated arc therapy (VMAT) treatment planning technique for supine craniospinal irradiation (CSI). Evaluate the suitability of VMAT for CSI with dosimetric measurements and compare it to 3D conformal planning using specific plan metrics such as dose conformity, homogeneity, and dose of organs at risk (OAR). Methods: Ten CSI patients treated with conventional 3D technique were re-planned with VMAT. The PTV was contoured to include the whole contents of the brain and spinal canal with a uniform margin of 5 mm. VMAT plans were generated with two partial arcs covering the brain, two partial arcs for the superior portion of the spinal cord and two partial arcs covering the remaining inferior portion of the spinal cord. Conformity index (CI), heterogeneity indexes (HI) and max and mean doses of OAR were compared to 3D plans. VMAT plans were delivered onto an anthropomorphic phantom loaded with Gafchromic films and OSLDs placed at specific positions to evaluate the plan dose at the junctions and as well as the plan dose distributions. Results: This VMAT technique was validated with a clinical study of 10 patients. The average CI was 1.03±0.02 for VMAT plans and 1.96±0.32 for conformal plans. And the average HI was 1.15±0.01 for VMAT plans and 1.51±0.21 for conformal plans. The mean and max doses to the all OARs for VMAT plans were significantly lower than conformal plans. The measured dose in phantom for VAMT plans was comparable to the calculated dose in Eclipse and the doses at junctions were verified. Conclusion: VMAT CSI was able to achieve better dose conformity and heterogeneity as well as significantly reducing the dose to Heart, esophagus and larynx. VMAT CSI appears to be a dosimterically advantageous, faster delivery, has better reproducibility CSI treatment.

  7. Circadian adaptation to night shift work influences sleep, performance, mood and the autonomic modulation of the heart.

    Directory of Open Access Journals (Sweden)

    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.

  8. Bacteriophage module reshuffling results in adaptive host range as exemplified by the baseplate model of listerial phage A118.

    Science.gov (United States)

    Cambillau, Christian

    2015-10-01

    Each phage infects its specific bacterial host strain through highly specific interactions between the baseplate-associated receptor binding protein (RBP) at the tip of the phage tail and the receptor at the host surface. Baseplates incorporate structural core modules, Dit and Tal, largely conserved among phages, and peripheral modules anchoring the RBPs. Exploiting structural information from the HHpred program and EM data from the Bielmann et al. (2015) paper, a molecular model of the A118 phage baseplate was generated from different building blocks. This model implies the occurrence of baseplate module reshuffling and suggests that listerial phage A118 may have been derived from lactococcal phage TP901-1 through host species exchange. With the increase of available viral module structures, modelling phage baseplates will become easier and more reliant, and will provide insightful information on the nature of the phage host receptor and its mode of recognition. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Multidsciplinary Approaches to Coastal Adaptation - Aplying Machine Learning Techniques to assess coastal risk in Latin America and The Caribbean

    Science.gov (United States)

    Calil, J.

    2016-12-01

    The global population, currently at 7.3 billion, is increasing by nearly 230,000 people every day. As the world's population grows to an estimated 11.2 billion by 2100, the number of people living in low elevation areas, exposed to coastal hazards, is continuing to increase. In 2013, 22 million people were displaced by extreme weather events, with 37 events displacing at least 100,000 people each. Losses from natural disasters and disaster risk are determined by a complex interaction between physical hazards and the vulnerability of a society or social-ecological system, and its exposure to such hazards. Impacts from coastal hazards depend on the number of people, value of assets, and presence of critical resources in harm's way. Moreover, coastal risks are amplified by challenging socioeconomic dynamics, including ill-advised urban development, income inequality, and poverty level. Our results demonstrate that in Latin America and the Caribbean (LAC), more than half a million people live in areas where coastal hazards, exposure (of people, assets and ecosystems), and poverty converge, creating the ideal conditions for a perfect storm. In order to identify the population at greatest risk to coastal hazards in LAC, and in response to a growing demand for multidisciplinary coastal adaptation approaches, this study employs a combination of machine learning clustering techniques (K-Means and Self Organizing Maps), and a spatial index, to assess coastal risks on a comparative scale. Data for more than 13,000 coastal locations in LAC were collected and allocated into three categories: (1) Coastal Hazards (including storm surge, wave energy and El Niño); (2) Geographic Exposure (including population, agriculture, and ecosystems); and (3) Vulnerability (including income inequality, infant mortality rate and malnutrition). This study identified hotspots of coastal vulnerability, the key drivers of coastal risk at each geographic location. Our results provide important

  10. SU-F-T-85: Energy Modulated Electron Postmastectomy Unreconstructed (PU) Chest Wall (CW) Irradiation Technique to Achieve Heart Sparing

    Energy Technology Data Exchange (ETDEWEB)

    Hong, L; Ballangrud, A; Mechalakos, J [Memorial Sloan-Kettering Cancer Center, New York, NY (United States); McCormick, B [Memerial Sloan-Kettering Cancer Center, New York, NY (United States)

    2016-06-15

    Purpose: For left-sided PU patients requiring CW and nodal irradiation, sometimes partial wide tangents (PWT) are not feasible due to abnormal chest wall contour or heart position close to the anterior chest wall or unusual wide excision scar. We developed an energy modulated electron chest wall irradiation technique that will achieve heart sparing. Methods: Ten left-sided PU patients were selected for this dosimetry study. If PWT were used, the amount of the ipsilateral lung would be ranged 3.4 to 4.4 cm, and the amount of heart would be ranged 1.3 to 3.8 cm. We used electron paired fields that matched on the skin to achieve dose conformity to the chest wall. The enface electron fields were designed at extended SSD from a single isocenter and gantry angle with different energy beams using different cutout. Lower energy was used in the central chest wall part and higher energy was used in the periphery of the chest wall. Bolus was used for the electron fields to ensure adequate skin dose coverage. The electron fields were matched to the photon supra-clavicle field in the superior region. Daily field junctions were used to feather the match lines between all the fields. Target volumes and normal tissues were drawn according to institutional protocols. Prescription dose was 2Gy per fraction for a total 50Gy. Dose calculations were done with Eclipse EMC-11031 for Electron and AAA-11031 for photons. Results: Six patients were planned using 6/9MeV, three using 9/12MeV and one 6/12MeV. Target volumes achieved adequate coverage. For heart, V30Gy, V20Gy and Mean Dose were 0.6%±0.6%, 2.7%±1.7%, and 3.0Gy±0.8Gy respectively. For ipsilateral lung, V50Gy, V20Gy, V10Gy and V5Gy were 0.9%±1.1%, 34.3%±5.1%, 51.6%±6.3% and 64.1%±7.5% respectively. Conclusion: For left-sided PU patients with unusual anatomy, energy modulated electron CW irradiation technique can achieve heart sparing with acceptable lung dose.

  11. Dosimetric study of volumetric arc modulation with RapidArc and intensity-modulated radiotherapy in patients with cervical cancer and comparison with 3-dimensional conformal technique for definitive radiotherapy in patients with cervical cancer

    Energy Technology Data Exchange (ETDEWEB)

    Guy, Jean-Baptiste [Department of Radiation Oncology, Institut de Cancérologie de la Loire Lucien Neuwirth, Saint-Priest en Jarez (France); Falk, Alexander T. [Department of Radiation Oncology, Centre Antoine Lacassagne, Nice (France); Auberdiac, Pierre [Department of Radiation Oncology, Clinique Claude Bernard, Albi (France); Cartier, Lysian; Vallard, Alexis [Department of Radiation Oncology, Institut de Cancérologie de la Loire Lucien Neuwirth, Saint-Priest en Jarez (France); Ollier, Edouard [Department of Pharmacology-Toxicology, Centre Hospitalier Universitaire de Saint-Etienne, Saint-Priest en Jarez (France); Trone, Jane-Chloé; Khodri, Moustapha [Department of Radiation Oncology, Institut de Cancérologie de la Loire Lucien Neuwirth, Saint-Priest en Jarez (France); Chargari, Cyrus [Department of Radiation Oncology, Hôpital d’instruction de Armées du Val-de-Grâce, Paris (France); Magné, Nicolas, E-mail: nicolas.magne@icloire.fr [Department of Radiation Oncology, Institut de Cancérologie de la Loire Lucien Neuwirth, Saint-Priest en Jarez (France)

    2016-04-01

    Introduction: For patients with cervical cancer, intensity-modulated radiation therapy (IMRT) improves target coverage and allows dose escalation while reducing the radiation dose to organs at risk (OARs). In this study, we compared dosimetric parameters among 3-dimensional conformal radiotherapy (3D-CRT), “step-and-shoot” IMRT, and volumetric intensity-modulated arc radiotherapy (VMAT) in a series of patients with cervical cancer receiving definitive radiotherapy. Computed tomography (CT) scans of 10 patients with histologically proven cervical cancer treated with definitive radiation therapy (RT) from December 2008 to March 2010 at our department were selected for this study. The gross tumor volume (GTV) and clinical target volume (CTV) were delineated following the guidelines of the Gyn IMRT consortium that included cervix, uterus, parametrial tissues, and the pelvic nodes including presacral. The median age was 57 years (range: 30 to 85 years). All 10 patients had squamous cell carcinoma with Federation of Gynecology and Obstetrics (FIGO) stage IB-IIIB. All patients were treated by VMAT. OAR doses were significantly reduced for plans with intensity-modulated technique compared with 3D-CRT except for the dose to the vagina. Between the 2 intensity-modulated techniques, significant difference was observed for the mean dose to the small intestine, to the benefit of VMAT (p < 0.001). There was no improvement in terms of OARs sparing for VMAT although there was a tendency for a slightly decreased average dose to the rectum: − 0.65 Gy but not significant (p = 0.07). The intensity modulation techniques have many advantages in terms of quality indexes, and particularly OAR sparing, compared with 3D-CRT. Following the ongoing technologic developments in modern radiotherapy, it is essential to evaluate the intensity-modulated techniques on prospective studies of a larger scale.

  12. Radiological and clinical pneumonitis after stereotactic lung radiotherapy: a matched analysis of three-dimensional conformal and volumetric-modulated arc therapy techniques.

    Science.gov (United States)

    Palma, David A; Senan, Suresh; Haasbeek, Cornelis J A; Verbakel, Wilko F A R; Vincent, Andrew; Lagerwaard, Frank

    2011-06-01

    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). 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. 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). 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. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Circadian Adaptation to Night Shift Work Influences Sleep, Performance, Mood and the Autonomic Modulation of the Heart

    Science.gov (United States)

    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

  14. Tangential Volumetric Modulated Radiotherapy - A New Technique for Large Scalp Lesions with a Case Study in Lentigo Maligna

    Directory of Open Access Journals (Sweden)

    E. Daniel Santos

    2015-06-01

    Full Text Available Introduction: Dose homogeneity within and dose conformity to the target volume can be a challenge to achieve when treating large area scalp lesions. Traditionally High Dose Rate (HDR brachytherapy (BT scalp moulds have been considered the ultimate conformal therapy. We have developed a new technique, Tangential Volumetric Modulated Arc Therapy (TVMAT that treats with the beam tangential to the surface of the scalp. In the TVMAT plan the collimating jaws protect dose-sensitive tissue in close proximity to the planning target volume (PTV. Not all the PTV is within the beam aperture as defined by the jaws during all the beam-on time. We report the successful treatment of one patient. Methods: A patient with biopsy proven extensive lentigo maligna on the scalp was simulated and three plans were created; one using a HDR brachytherapy surface mould, another using a conventional VMAT technique and a third using our new TVMAT technique. The patient was prescribed 55 Gy in 25 fractions. Plans were optimised so that PTV V100% = 100%. Plans were compared using Dose-Value Histogram (DVH analysis, and homogeneity and conformity indices. Results: BT, VMAT and TVMAT PTV median coverage was 105.51%, 103.46% and 103.62%, with homogeneity index of 0.33, 0.07 and 0.07 and the conformity index of 0.30, 0.69 and 0.83 respectively. The median dose to the left hippocampus was 11.8 Gy, 9.0 Gy and 0.6 Gy and the median dose to the right hippocampus was 12.6 Gy, 9.4 Gy and 0.7 Gy for the BT, VMAT and TVMAT respectively. Overall TVMAT delivered the least doses to the surrounding organs, BT delivered the highest. Conclusions: TVMAT was superior to VMAT which was in turn superior to BT in PTV coverage, conformity and homogeneity and delivery of dose to the surrounding organs at risk. The patient was successfully treated to full dose with TVMAT. TVMAT was verified as being the best amongst the three techniques in a second patient.

  15. In-line monitoring technique with visible light from 1.3 microm-band SHG module for optical access systems.

    Science.gov (United States)

    Kubo, Takahiro; Taniguchi, Tomohiro; Tadanaga, Osamu; Sakurai, Naoya; Kimura, Hideaki; Hadama, Hisaya; Asobe, Masaki

    2010-02-01

    We propose an in-line monitoring technique that uses 650 nm visible light for performing maintenance work on Fiber-to-the-home (FTTH) network quickly without the need for measuring skills or external devices. This technique is characterized by visible light (650 nm) generated by an SHG module from the 1.3 microm-band line signal. We fabricate a 1.3 microm-band quasi phase matched LiNbO(3) (QPM-LN) module, and the measure the 650 nm second harmonic (SH) power to test the proposed short-pulse modulation method. The results confirm the feasibility of the short-pulse modulation method with different peak factors (PFs) (1.0-7.3). We also examine the effect of short-pulse modulation on system performance at the optical receiver by measuring the bit error rate (BER) of received data (1.25 Gb/s). The BER is basically unaffected by the PF (1.0-5.5). This means that the proposed technique has little influence on data reception as regards PF (1.0-5.5).

  16. Residual stress in a laser welded EUROFER blanket module assembly using non-destructive neutron diffraction techniques

    International Nuclear Information System (INIS)

    Hughes, D.J.; Koukovini-Platia, E.; Heeley, E.L.

    2014-01-01

    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

  17. Borrelia host adaptation Regulator (BadR) regulates rpoS to modulate host adaptation and virulence factors in Borrelia burgdorferi

    OpenAIRE

    Miller, Christine L.; Rajasekhar Karna, S. L.; Seshu, J.

    2013-01-01

    The RpoS transcription factor of Borrelia burgdorferi is a “gatekeeper” because it activates genes required for spirochetes to transition from tick to vertebrate hosts. However, it remains unknown how RpoS becomes repressed to allow the spirochetes to transition back from the vertebrate host to the tick vector. Here we show that a putative carbohydrate-responsive regulatory protein, designated BadR (Borrelia host adaptation Regulator), is a transcriptional repressor of rpoS. BadR levels are e...

  18. Adaptive Data Processing Technique for Lidar-Assisted Control to Bridge the Gap between Lidar Systems and Wind Turbines: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Adaptive filtering techniques for gravitational wave interferometric data: Removing long-term sinusoidal disturbances and oscillatory transients

    Science.gov (United States)

    Chassande-Mottin, E.; Dhurandhar, S. V.

    2001-02-01

    It is known by the experience gained from the gravitational wave detector prototypes that the interferometric output signal will be corrupted by a significant amount of non-Gaussian noise, a large part of it being essentially composed of long-term sinusoids with a slowly varying envelope (such as violin resonances in the suspensions, or main power harmonics) and short-term ringdown noise (which may emanate from servo control systems, electronics in a nonlinear state, etc.). Since non-Gaussian noise components make the detection and estimation of the gravitational wave signature more difficult, a denoising algorithm based on adaptive filtering techniques (LMS methods) is proposed to separate and extract them from the stationary and Gaussian background noise. The strength of the method is that it does not require any precise model on the observed data: the signals are distinguished on the basis of their autocorrelation time. We believe that the robustness and simplicity of this method make it useful for data preparation and for the understanding of the first interferometric data. We present the detailed structure of the algorithm and its application to both simulated data and real data from the LIGO 40 m prototype.

  20. A High-Precision Adaptive Thermal Network Model for Monitoring of Temperature Variations in Insulated Gate Bipolar Transistor (IGBT Modules

    Directory of Open Access Journals (Sweden)

    Ning An

    2018-03-01

    Full Text Available This paper proposes a novel method for optimizing the Cauer-type thermal network model considering both the temperature influence on the extraction of parameters and the errors caused by the physical structure. In terms of prediction of the transient junction temperature and the steady-state junction temperature, the conventional Cauer-type parameters are modified, and the general method for estimating junction temperature is studied by using the adaptive thermal network model. The results show that junction temperature estimated by our adaptive Cauer-type thermal network model is more accurate than that of the conventional model.

  1. Phase modulation detection with liquid crystal light valve and digital holography

    Science.gov (United States)

    Residori, Stefania; Bortolozzo, Umberto; Peigné, Arnaud; Molin, Stephanie; Dolfi, Daniel; Huignard, Jean-Pierre

    2017-06-01

    Self-adaptive interferometry allows the measurement of small optical phase modulations in noisy environments and with strongly distorted optical wavefronts. We review two techniques of self-adaptive interferometers based on liquid crystals spatial light modulators, one obtained by using an optically addressed light valve, the second one realized by adopting a digital holography CMOS-LCOS scheme. The adaptive character of these two types of holographic interferometers will be analyzed and compared.

  2. Direction Modulated Brachytherapy for Treatment of Cervical Cancer. II: Comparative Planning Study With Intracavitary and Intracavitary–Interstitial Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dae Yup [Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Department of Radiation Oncology, University of California, San Francisco, San Francisco, California (United States); Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California (United States); Safigholi, Habib; Soliman, Abraam [Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario (Canada); Ravi, Ananth [Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Leung, Eric [Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Department of Radiation Oncology, Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Scanderbeg, Daniel J. [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States); Liu, Zhaowei [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California (United States); Owrangi, Amir [Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Song, William Y., E-mail: william.song@sunnybrook.ca [Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada)

    2016-10-01

    Purpose: To perform a comprehensive comparative planning study evaluating the utility of the proposed direction modulated brachytherapy (DMBT) tandem applicator against standard applicators, in the setting of image guided adaptive brachytherapy of cervical cancer. Methods and Materials: A detailed conceptual article was published in 2014. The proposed DMBT tandem applicator has 6 peripheral grooves of 1.3-mm width, along a 5.4-mm-thick nonmagnetic tungsten alloy rod of density 18.0 g/cm{sup 3}, capable of generating directional dose profiles. We performed a comparative planning study with 45 cervical cancer patients enrolled consecutively in the prospective observational EMBRACE study. In all patients, MRI-based planning was performed while utilizing various tandem-ring (27 patients) and tandem-ring-needles (18 patients) applicators, in accordance with the Groupe Européen de Curiethérapie–European Society for Radiotherapy and Oncology recommendations. For unbiased comparisons, all cases were replanned with an in-house–developed inverse optimization code while enforcing a uniform set of constraints that are reflective of the clinical practice. All plans were normalized to the same high-risk clinical target volume D90 values achieved in the original clinical plans. Results: In general, if the standard tandem was replaced with the DMBT tandem while maintaining all other planning conditions the same, there was consistent improvement in the plan quality. For example, among the 18 tandem-ring-needles cases, the average D2cm{sup 3} reductions achieved were −2.48% ± 11.03%, −4.45% ± 5.24%, and −5.66% ± 6.43% for the bladder, rectum, and sigmoid, respectively. An opportunity may also exist in avoiding use of needles altogether for when the total number of needles required is small (approximately 2 to 3 needles or less), if DMBT tandem is used. Conclusions: Integrating the novel DMBT tandem onto both intracavitary and intracavitary

  3. Comparison of conformal and intensity modulated radiation therapy techniques for treatment of pelvic tumors. Analysis of acute toxicity

    International Nuclear Information System (INIS)

    Ferrigno, Robson; Santos, Adriana; Martins, Lidiane C; Weltman, Eduardo; Chen, Michael J; Sakuraba, Roberto; Lopes, Cleverson P; Cruz, José C

    2010-01-01

    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

  4. Spectrally-Temporally Adapted Spectrally Modulated Spectrally Encoded (SMSE) Waveform Design for Coexistent CR-Based SDR Applications

    Science.gov (United States)

    2010-03-01

    Only and Spectrally-Temporally adapted SMSE signals at var - ious levels channel estimate MSE. Results based on a maximum BER constraint of PB = 10 −2...57. Tian, Z. and G. B. Giannakis. “A Wavelet Approach to Wideband Spectrum Sensing for Cognitive Radios”. Proceedings of the 1st International

  5. An effective Load shedding technique for micro-grids using artificial neural network and adaptive neuro-fuzzy inference system

    Directory of Open Access Journals (Sweden)

    Foday Conteh

    2017-09-01

    Full Text Available In recent years, the use of renewable energy sources in micro-grids has become an effectivemeans of power decentralization especially in remote areas where the extension of the main power gridis an impediment. Despite the huge deposit of natural resources in Africa, the continent still remains inenergy poverty. Majority of the African countries could not meet the electricity demand of their people.Therefore, the power system is prone to frequent black out as a result of either excess load to the systemor generation failure. The imbalance of power generation and load demand has been a major factor inmaintaining the stability of the power systems and is usually responsible for the under frequency andunder voltage in power systems. Currently, load shedding is the most widely used method to balancebetween load and demand in order to prevent the system from collapsing. But the conventional methodof under frequency or under voltage load shedding faces many challenges and may not perform asexpected. This may lead to over shedding or under shedding, causing system blackout or equipmentdamage. To prevent system cascade or equipment damage, appropriate amount of load must beintentionally and automatically curtailed during instability. In this paper, an effective load sheddingtechnique for micro-grids using artificial neural network and adaptive neuro-fuzzy inference system isproposed. The combined techniques take into account the actual system state and the exact amount ofload needs to be curtailed at a faster rate as compared to the conventional method. Also, this methodis able to carry out optimal load shedding for any input range other than the trained data. Simulationresults obtained from this work, corroborate the merit of this algorithm.

  6. Inclusion of the fitness sharing technique in an evolutionary algorithm to analyze the fitness landscape of the genetic code adaptability.

    Science.gov (United States)

    Santos, José; Monteagudo, Ángel

    2017-03-27

    The canonical code, although prevailing in complex genomes, is not universal. It was shown the canonical genetic code superior robustness compared to random codes, but it is not clearly determined how it evolved towards its current form. The error minimization theory considers the minimization of point mutation adverse effect as the main selection factor in the evolution of the code. We have used simulated evolution in a computer to search for optimized codes, which helps to obtain information about the optimization level of the canonical code in its evolution. A genetic algorithm searches for efficient codes in a fitness landscape that corresponds with the adaptability of possible hypothetical genetic codes. The lower the effects of errors or mutations in the codon bases of a hypothetical code, the more efficient or optimal is that code. The inclusion of the fitness sharing technique in the evolutionary algorithm allows the extent to which the canonical genetic code is in an area corresponding to a deep local minimum to be easily determined, even in the high dimensional spaces considered. The analyses show that the canonical code is not in a deep local minimum and that the fitness landscape is not a multimodal fitness landscape with deep and separated peaks. Moreover, the canonical code is clearly far away from the areas of higher fitness in the landscape. Given the non-presence of deep local minima in the landscape, although the code could evolve and different forces could shape its structure, the fitness landscape nature considered in the error minimization theory does not explain why the canonical code ended its evolution in a location which is not an area of a localized deep minimum of the huge fitness landscape.

  7. All Internal Segmental Bone Transport and Optional Lengthening With a Newly Developed Universal Cylinder-Kombi-Tube Module for Motorized Nails-Description of a Surgical Technique.

    Science.gov (United States)

    Krettek, Christian; El Naga, Ashraf

    2017-10-01

    Segmental transport is an effective method of treatment for segmental defects, but the need for external fixation during the transport phase is a disadvantage. To avoid external fixation, we have developed a Cylinder-Kombi-Tube Segmental Transport (CKTST) module for combination with a commercially available motorized lengthening nail. This CKTST module allows for an all-internal segmental bone transport and also allows for optional lengthening if needed. The concept and surgical technique of CKTST are described and illustrated with a clinical case.

  8. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  9. A case study on use of modified delphi technique for developing consensus on designing contents of a module for imparting sex education to adolescents in schools, in India

    Directory of Open Access Journals (Sweden)

    Deepak B. Saxena

    2012-06-01

    Full Text Available In the year 2007, eleven (11 of India’s 29 states suspended the federal initiative, ‘Adolescence Education Program’, under the name of School AIDS awareness education program (SAEP designed for 15- to 17-year-olds in all staterun schools and devised by the Ministry of Human Resource Development (HRD and National AIDS Control Organization (NACO on grounds that the flip charts used for training teachers contained explicit images of male and female reproductive systems, conception, and contraception. The aim of the present study is to understand usefulness of Delphi technique as a tool to develop contents and make consensus over a suitable module that can be utilized for imparting Sex Education to the Adolescents in school. The study present below used Delphi technique in transaction of the module recommended by National Council of Education Research and Training (NCERT for imparting Sex education under SAEP. Although the technique was successful in building consensus amongst different stake holders, within the limitations of Delphi like potential drop outs, loss to follow up and lack of clear verbal labels. It is concluded from the results of present study that Delphi technique, when rigorously administered, analyzed and reported, is a valuable method to help policy planners in developing the process for a suitable module that can be utilized for imparting sex education to adolescents in school.

  10. A case study on use of modified delphi technique for developing consensus on designing contents of a module for imparting sex education to adolescents in schools, in India

    Directory of Open Access Journals (Sweden)

    Deepak B. Saxena

    2012-01-01

    Full Text Available In the year 2007, eleven (11 of India’s 29 states suspended the federal initiative, ‘Adolescence Education Program’, under the name of School AIDS awareness education program (SAEP designed for 15- to 17-year-olds in all state- run schools and devised by the Ministry of Human Resource Development (HRD and National AIDS Control Organization (NACO on grounds that the flip charts used for training teachers contained explicit images of male and female reproductive systems, conception, and contraception. The aim of the present study is to understand usefulness of Delphi technique as a tool to develop contents and make consensus over a suitable module that can be utilized for imparting Sex Education to the Adolescents in school. The study present below used Delphi technique in transaction of the module recommended by National Council of Education Research and Training (NCERT for imparting Sex education under SAEP. Although the technique was successful in building consensus amongst different stake holders, within the limitations of Delphi like potential drop outs, loss to follow up and lack of clear verbal labels. It is concluded from the results of present study that Delphi technique, when rigorously administered, analyzed and reported, is a valuable method to help policy planners in developing the process for a suitable module that can be utilized for imparting sex education to adolescents in school

  11. Marginal adaptation of mineral trioxide aggregate (MTA) to root dentin surface with orthograde/retrograde application techniques: A microcomputed tomographic analysis.

    Science.gov (United States)

    Al Fouzan, Khalid; Awadh, Mohammed; Badwelan, Moahmmed; Gamal, Abeer; Geevarghese, Amrita; Babhair, Samar; Al-Rejaie, Mansour; Al Hezaimi, Khalid; Rotstein, Ilan

    2015-01-01

    Achieving a good apical seal for root canals is known to be associated with good mineral trioxide aggregate (MTA) adaptation to dentin. 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. 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). 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. 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%. 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 MTA adaptation, instead with the use of 17% EDTA, a significant improvement could be achieved. 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.

  12. A Fast Hartley Transform based novel optical OFDM system for VLC indoor application with constant envelope PAPR reduction technique using frequency modulation

    Science.gov (United States)

    Singh, Vinay Kumar; Dalal, U. D.

    2017-10-01

    In this research literature we present a unique optical OFDM system for Visible Light Communication (VLC) intended for indoor application which uses a non conventional transform-Fast Hartley Transform and an effective method to reduce the peak to average power ratio (PAPR) of the OFDM signal based on frequency modulation leading to a constant envelope (CE) signal. The proposed system is analyzed by a complete mathematical model and verified by the concurrent simulations results. The use of the non conventional transform makes the system computationally more desirable as it does not require the Hermitian symmetry constraint to yield real signals. The frequency modulation of the baseband signal converge random peaks into a CE signal. This leads to alleviation of the non linearity effects of the LED used in the link for electrical to optical conversion. The PAPR is reduced to 2 dB by this technique in this work. The impact of the modulation index on the performance of the system is also investigated. An optimum modulation depth of 30% gives better results. The additional phase discontinuity incurring on the demodulated signal at the receiver is also significantly reduced. A comparison of the improvement in phase discontinuity of the proposed technique of combating the PAPR with the previously known phase modulation technique is also presented in this work. Based on the channel metrics we evaluate the system performance and report an improvement of 1.2 dB at the FEC threshold. The proposed system is simple in design and computationally efficient and this can be incorporated into the present VLC system without much alteration thereby making it a cost effective solution.

  13. Comparative evaluation of marginal fit and axial wall adaptability of copings fabricated by metal laser sintering and lost-wax technique: Anin vitrostudy.

    Science.gov (United States)

    Gaikwad, Bhushan Satish; Nazirkar, Girish; Dable, Rajani; Singh, Shailendra

    2018-01-01

    The present study aims to compare and evaluate the marginal fit and axial wall adaptability of Co-Cr copings fabricated by metal laser sintering (MLS) and lost-wax (LW) techniques using a stereomicroscope. A stainless steel master die assembly was fabricated simulating a prepared crown; 40 replicas of master die were fabricated in gypsum type IV and randomly divided in two equal groups. Group A coping was fabrication by LW technique and the Group B coping fabrication by MLS technique. The copings were seated on their respective gypsum dies and marginal fit was measured using stereomicroscope and image analysis software. For evaluation of axial wall adaptability, the coping and die assembly were embedded in autopolymerizing acrylic resin and sectioned vertically. The discrepancies between the dies and copings were measured along the axial wall on each halves. The data were subjected to statistical analysis using unpaired t -test. The mean values of marginal fit for copings in Group B (MLS) were lower (24.6 μm) than the copings in Group A (LW) (39.53 μm), and the difference was statistically significant ( P < 0.05). The mean axial wall discrepancy value was lower for Group B (31.03 μm) as compared with Group A (54.49 μm) and the difference was statistically significant ( P < 0.05). The copings fabricated by MLS technique had better marginal fit and axial wall adaptability in comparison with copings fabricated by the LW technique. However, the values of marginal fit of copings fabricated that the two techniques were within the clinically acceptable limit (<50 μm).

  14. Comparison of marginal and internal adaptation of copings fabricated from three different fabrication techniques: An in vitro study

    Directory of Open Access Journals (Sweden)

    Aman Arora

    2018-01-01

    Conclusion: Marginal and internal discrepancies of all the three casting techniques were within clinically acceptable values. Marginal fit of DMLS was superior as compared to other two techniques, whereas when internal fit was evaluated, conventional technique showed the best internal fit.

  15. Electrical and mechanical adaptation of commercially available power inverter modules for BUSSARD – The power supply of ASDEX Upgrade in vessel saddle coils

    Energy Technology Data Exchange (ETDEWEB)

    Rott, Michael, E-mail: Michael.Rott@ipp.mpg.de [Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, D-85748 Garching (Germany); Arden, Nils; Eixenberger, Horst [Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, D-85748 Garching (Germany); Klädtke, Kevin [Technical University Munich, Arcisstraße 21, D-80333 München (Germany); Teschke, Markus; Suttrop, Wolfgang [Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, D-85748 Garching (Germany)

    2015-10-15

    Highlights: • Mechanical design of inverters for restricted space and good mountability. • Supply of DC link possible with thyristor converter. • Plant safety by independent overcurrent protections and a commercially arc detection system. • Ground fault detection by fast differential current measurement. • Possibilities of changing the inductance of a two windings iron core choke. - Abstract: To supply the ASDEX Upgrade's B-coils with AC current up to 1.3 kA{sub p} at 500 Hz with arbitrary waveforms, a set of 16 inverters has been designed and partially built. To keep cost and development time low, commercially available power modules are used and existing current converters feed the DC links. Three power modules are mounted in one cubicle for realizing a three level neutral point clamped (NPC) topology with lowest possible inductivity and making the most of the limited space available. The paper presents the effort and steps required to adapt standard power blocks towards the needs of the ASDEX Upgrade power supply as well as the mechanical optimizations for good mountability, flexibility and scalability. Besides, solutions for mandatory personnel safety and plant safety are presented.

  16. 4.5-Gb/s RGB-LED based WDM visible light communication system employing CAP modulation and RLS based adaptive equalization.

    Science.gov (United States)

    Wang, Yiguang; Huang, Xingxing; Tao, Li; Shi, Jianyang; Chi, Nan

    2015-05-18

    Inter-symbol interference (ISI) is one of the key problems that seriously limit transmission data rate in high-speed VLC systems. To eliminate ISI and further improve the system performance, series of equalization schemes have been widely investigated. As an adaptive algorithm commonly used in wireless communication, RLS is also suitable for visible light communication due to its quick convergence and better performance. In this paper, for the first time we experimentally demonstrate a high-speed RGB-LED based WDM VLC system employing carrier-less amplitude and phase (CAP) modulation and recursive least square (RLS) based adaptive equalization. An aggregate data rate of 4.5Gb/s is successfully achieved over 1.5-m indoor free space transmission with the bit error rate (BER) below the 7% forward error correction (FEC) limit of 3.8x10(-3). To the best of our knowledge, this is the highest data rate ever achieved in RGB-LED based VLC systems.

  17. Volume and dosimetric changes and initial clinical experience of a two-step adaptive intensity modulated radiation therapy (IMRT) scheme for head and neck cancer

    International Nuclear Information System (INIS)

    Nishi, Tamaki; Nishimura, Yasumasa; Shibata, Toru; Tamura, Masaya; Nishigaito, Naohiro; Okumura, Masahiko

    2013-01-01

    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. D 2 (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

  18. Anatomical robust optimization to account for nasal cavity filling variation during intensity-modulated proton therapy: a comparison with conventional and adaptive planning strategies.

    Science.gov (United States)

    van de Water, Steven; Albertini, Francesca; Weber, Damien C; Heijmen, Ben J M; Hoogeman, Mischa S; Lomax, Antony J

    2018-01-11

    The aim of this study is to develop an anatomical robust optimization method for intensity-modulated proton therapy (IMPT) that accounts for interfraction variations in nasal cavity filling, and to compare it with conventional single-field uniform dose (SFUD) optimization and online plan adaptation. We included CT data of five patients with tumors in the sinonasal region. Using the planning CT, we generated for each patient 25 'synthetic' CTs with varying nasal cavity filling. The robust optimization method available in our treatment planning system 'Erasmus-iCycle' was extended to also account for anatomical uncertainties by including (synthetic) CTs with varying patient anatomy as error scenarios in the inverse optimization. For each patient, we generated treatment plans using anatomical robust optimization and, for benchmarking, using SFUD optimization and online plan adaptation. Clinical target volume (CTV) and organ-at-risk (OAR) doses were assessed by recalculating the treatment plans on the synthetic CTs, evaluating dose distributions individually and accumulated over an entire fractionated 50 Gy RBE treatment, assuming each synthetic CT to correspond to a 2 Gy RBE fraction. Treatment plans were also evaluated using actual repeat CTs. Anatomical robust optimization resulted in adequate CTV doses (V 95%   ⩾  98% and V 107%   ⩽  2%) if at least three synthetic CTs were included in addition to the planning CT. These CTV requirements were also fulfilled for online plan adaptation, but not for the SFUD approach, even when applying a margin of 5 mm. Compared with anatomical robust optimization, OAR dose parameters for the accumulated dose distributions were on average 5.9 Gy RBE (20%) higher when using SFUD optimization and on average 3.6 Gy RBE (18%) lower for online plan adaptation. In conclusion, anatomical robust optimization effectively accounted for changes in nasal cavity filling during IMPT, providing substantially improved CTV and

  19. Anatomical robust optimization to account for nasal cavity filling variation during intensity-modulated proton therapy: a comparison with conventional and adaptive planning strategies

    Science.gov (United States)

    van de Water, Steven; Albertini, Francesca; Weber, Damien C.; Heijmen, Ben J. M.; Hoogeman, Mischa S.; Lomax, Antony J.

    2018-01-01

    The aim of this study is to develop an anatomical robust optimization method for intensity-modulated proton therapy (IMPT) that accounts for interfraction variations in nasal cavity filling, and to compare it with conventional single-field uniform dose (SFUD) optimization and online plan adaptation. We included CT data of five patients with tumors in the sinonasal region. Using the planning CT, we generated for each patient 25 ‘synthetic’ CTs with varying nasal cavity filling. The robust optimization method available in our treatment planning system ‘Erasmus-iCycle’ was extended to also account for anatomical uncertainties by including (synthetic) CTs with varying patient anatomy as error scenarios in the inverse optimization. For each patient, we generated treatment plans using anatomical robust optimization and, for benchmarking, using SFUD optimization and online plan adaptation. Clinical target volume (CTV) and organ-at-risk (OAR) doses were assessed by recalculating the treatment plans on the synthetic CTs, evaluating dose distributions individually and accumulated over an entire fractionated 50 GyRBE treatment, assuming each synthetic CT to correspond to a 2 GyRBE fraction. Treatment plans were also evaluated using actual repeat CTs. Anatomical robust optimization resulted in adequate CTV doses (V95%  ⩾  98% and V107%  ⩽  2%) if at least three synthetic CTs were included in addition to the planning CT. These CTV requirements were also fulfilled for online plan adaptation, but not for the SFUD approach, even when applying a margin of 5 mm. Compared with anatomical robust optimization, OAR dose parameters for the accumulated dose distributions were on average 5.9 GyRBE (20%) higher when using SFUD optimization and on average 3.6 GyRBE (18%) lower for online plan adaptation. In conclusion, anatomical robust optimization effectively accounted for changes in nasal cavity filling during IMPT, providing substantially improved CTV and

  20. Growth modulation and remodeling by means of posterior tethering technique for correction of early-onset scoliosis with thoracolumbar kyphosis.

    Science.gov (United States)

    Ahmad, Alaaeldin A; Aker, Loai; Hanbali, Yahia; Sbaih, Aesha; Nazzal, Zaher

    2017-06-01

    The aim of this study is to evaluate the role of the non-fusion instrumented procedure with compression adjunct to lengthening by distraction in facilitating spinal modulation of the wedged peak vertebra, in patients with congenital thoracolumbar kyphosis/kyphoscoliosis according to the Hueter-Volkmann law. The authors seek to address the progressive modulation of the most wedged vertebra by analyzing the subjects' pre-operative and latest follow-up sagittal radiograph. Ongoing data collection of 14 peak wedged vertebra modulation during surgical management of 13 patients with Type I congenital thoracolumbar kyphosis (5 patients) or kyphoscoliosis (8 patients). Age at initial surgery averaged 58.6 months, with mean follow-up of 55.6 months (24-78). All were done with hybrid rib construct with clawing fashion through a single posterior approach with at least 4 lengthenings. Two vertebral bodies were selected, the peaked deformed vertebrae within the instrumentation compression level (WICL) and the vertebrae nearest but outside the instrumentation compression process (OICL). Anterior vertebral body height (AVBH) and posterior vertebral body height (PVBH) were measured in both vertebral bodies. Regarding measured vertebrae (WICL), average preoperative AVBH/PVBH ratio significantly increased from 0.54 to 0.77 in the final follow-up. Regarding measured vertebrae (OICL), the average preoperative AVBH/PVBH ratio increased from 0.76 to 0.79 in the final follow-up. Modulation can be confirmed in the most deformed vertebrae (WICL) as the difference between the change in AVBH/PVBH ratio between vertebrae (OICL) and (WICL) was statistically significant (P modulation (WICL) in comparison with the (OICL). This calls for further studies on the impact of surgical correction of EOS on modulation of the vertebrae.

  1. Contribution of the modulation of intensity and the optimization to deliver a dose adapted to the biological heterogeneities

    International Nuclear Information System (INIS)

    Kubs, F.

    2007-10-01

    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)

  2. A comparison of radiation treatment techniques for carcinomas of the larynx and hypopharynx using 3-D dose distributions and intensity modulation

    International Nuclear Information System (INIS)

    Morris, David; Miller, Elizabeth P.; Rosenman, Julian; Sailer, Scott; Tepper, Joel

    1997-01-01

    Purpose/Objective: Patients with carcinomas of the larynx and hypopharynx often cannot be treated effectively with a lateral/low anterior neck combination because the midline block will cover the tumor bed. Common alternatives to this approach often produce serious dose inhomogeneities. Our study was to determine whether modern 3D treatment planning techniques with intensity modulation could overcome these dose inhomogeneities and also allow us to omit the problematic posterior neck electron boost which often gives poor nodal coverage. Materials and Methods: Dose distribution studies were performed on patients who had received post-operative radiation following laryngectomy for advanced staged cancer. The clinical tumor volume or CTV (surgical bed and at-risk nodal stations) was defined on planning CT images. Four commonly used alternative plans, the MGH 'minimantle', 'kicked-out' laterals, the University of Florida 3-field, and a standard 3 field with a lateral cord block were evaluated using the Plan UNC (PLUNC) treatment planning software. New plans that might also preclude the use of posterior neck electrons were also evaluated. The plans were then intensity modulated to reduce the well known cold spots as described previously in IJROBP August 1991, Vol. 21, No. 3. All dose distributions were evaluated for dose homogeneity, minimum and maximum CTV dose, and dose to normal critical structures. The inhomogeneities were determined using standard dose-volume histogram (DVH) techniques but positional information was gathered by dividing the CTV into sensible anatomic regions and studying the DVH for each separately. Results: For the mini-mantle approach, intensity modulation substantially improved the dose inhomogeneities but did not affect the minimum CTV dose and had no effect on the cord dose. Intensity modulation decreased the maximum CTV dose (110% vs. 130%) but had the undesirable effect of lessening the dose difference between cord and CTV. For the kicked

  3. Verification of the CENTRM Module for Adaptation of the SCALE Code to NGNP Prismatic and PBR Core Designs

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Splenectomy inhibits non-small cell lung cancer growth by modulating anti-tumor adaptive and innate immune response

    Science.gov (United States)

    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 growth and the development of lung metastases, but only in advanced tumors. In immune-deficient NOD-SCID mice the effect of splenectomy on tumor growth and metastatic spread disappeared. Splenectomy significantly reduced the presence of MDSC, and especially monocytic-MDSC in the circulation and inside the tumor. Specific reduction of the CCR2+ subset of monocytic MDSC was demonstrated, and the importance of the CCL2-CCR2 axis was further shown by a marked reduction in CCL2 following splenectomy. These changes were followed by changes in the macrophages contents of the tumors to become more antitumorigenic, and by increased activation of CD8+ Cytotoxic T-cells (CTL). By MDSC depletion, and adoptive transfer of MDSCs, we demonstrated that the effect of splenectomy on tumor growth was substantially mediated by MDSC cells. We conclude that the spleen is an important contributor to tumor growth and metastases, and that splenectomy can blunt this effect by depletion of MDSC, changing the amount and characteristics of myeloid cells and enhancing activation of CTL. PMID:26137413

  5. Adapting developing country epidemiological assessment techniques to improve the quality of health needs assessments in developed countries

    Directory of Open Access Journals (Sweden)

    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.

  6. Glucose-Modulated Mitochondria Adaptation in Tumor Cells: A Focus on ATP Synthase and Inhibitor Factor 1

    Directory of Open Access Journals (Sweden)

    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.

  7. A cytosolic Ezh1 isoform modulates a PRC2–Ezh1 epigenetic adaptive response in postmitotic cells

    KAUST Repository

    Bodega, Beatrice

    2017-03-27

    The evolution of chromatin-based epigenetic cell memory may be driven not only by the necessity for cells to stably maintain transcription programs, but also by the need to recognize signals and allow plastic responses to environmental stimuli. The mechanistic role of the epigenome in adult postmitotic tissues, however, remains largely unknown. In vertebrates, two variants of the Polycomb repressive complex (PRC2-Ezh2 and PRC2-Ezh1) control gene silencing via methylation of histone H3 on Lys27 (H3K27me). Here we describe a reversible mechanism that involves a novel isoform of Ezh1 (Ezh1β). Ezh1β lacks the catalytic SET domain and acts in the cytoplasm of skeletal muscle cells to control nuclear PRC2-Ezh1 activity in response to atrophic oxidative stress, by regulating Eed assembly with Suz12 and Ezh1α (the canonical isoform) at their target genes. We report a novel PRC2-Ezh1 function that utilizes Ezh1β as an adaptive stress sensor in the cytoplasm, thus allowing postmitotic cells to maintain tissue integrity in response to environmental changes.

  8. SU-F-T-349: Dosimetric Comparison of Three Different Simultaneous Integrated Boost Irradiation Techniques for Multiple Brain Metastases: Intensity-Modulatedradiotherapy, Hybrid Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Lin, X; Sun, T; Yin, Y [Shandong Cancer Hospital and Institute, China, Jinan, Shandong (China)

    2016-06-15

    Purpose: To study the dosimetric impact of intensity-modulated radiotherapy (IMRT), hybrid intensity-modulated radiotherapy (h-IMRT) and volumetric modulated arc therapy(VMAT) for whole-brain radiotherapy (WBRT) with simultaneous integrated boost in patients with multiple brain metastases. Methods: Ten patients with multiple brain metastases were included in this analysis. The prescribed dose was 45 Gy to the whole brain (PTVWBRT) and 55 Gy to individual brain metastases (PTVboost) delivered simultaneously in 25 fractions. Three treatment techniques were designed: the 7 equal spaced fields IMRT plan, hybrid IMRT plan and VMAT with two 358°arcs. In hybrid IMRT plan, two fields(90°and 270°) were planned to the whole brain. This was used as a base dose plan. Then 5 fields IMRT plan was optimized based on the two fields plan. The dose distribution in the target, the dose to the organs at risk and total MU in three techniques were compared. Results: For the target dose, conformity and homogeneity in PTV, no statistically differences were observed in the three techniques. For the maximum dose in bilateral lens and the mean dose in bilateral eyes, IMRT and h-IMRT plans showed the highest and lowest value respectively. No statistically significant differences were observed in the dose of optic nerve and brainstem. For the monitor units, IMRT and VMAT plans showed the highest and lowest value respectively. Conclusion: For WBRT with simultaneous integrated boost in patients with multiple brain metastases, hybrid IMRT could reduce the doses to lens and eyes. It is feasible for patients with brain metastases.

  9. Dosimetric comparison of IMRT and modulated arc-therapy techniques in the treatment of cervical cancers; Comparaison dosimetrique des techniques de RCMI et d'arctherapie modulee dans le traitement des cancers du col uterin

    Energy Technology Data Exchange (ETDEWEB)

    Renard-Oldrini, S.; Charra-Brunaud, C.; Tournier-Rangeard, L.; Huger, S.; Marchesi, V.; Bouziz, D.; Peiffert, D. [Centre Alexis-Vautrin, Nancy (France)

    2011-10-15

    The authors report the dosimetric comparison of two techniques used for the treatment of cervical cancers: the intensity-modulated conformational radiotherapy (IMRT) with static beams and modulated arc-therapy with RapidArc. The treatment plans of 15 patients have been compared. The clinical target volume (CTV) comprises the gross target volume, the cervix, the upper third of the vagina, and ganglionary areas. The previsional target volume comprises the clinical target volume and a one centimetre margin. Organs at risk are rectum, bladder, intestine and bone marrow. Arc-therapy seems to provide a better sparing of intestine that IMRT, while maintaining a good coverage of the previsional target volume and decreasing treatment duration. Short communication

  10. REEPs are membrane shaping adapter proteins that modulate specific g protein-coupled receptor trafficking by affecting ER cargo capacity.

    Directory of Open Access Journals (Sweden)

    Susann Björk

    proteins. Therefore, some REEPs can be further described as ER membrane shaping adapter proteins.

  11. Techniques for Effective Optical Noise Rejection in Amplitude-Modulated Laser Optical Radars for Underwater Three-Dimensional Imaging

    Directory of Open Access Journals (Sweden)

    Francucci M

    2010-01-01

    Full Text Available Amplitude-modulated (AM laser imaging is a promising technology for the production of accurate three-dimensional (3D images of submerged scenes. The main challenge is that radiation scattered off water gives rise to a disturbing signal (optical noise that degrades more and more the quality of 3D images for increasing turbidity. In this paper, we summarize a series of theoretical findings, that provide valuable hints for the development of experimental methods enabling a partial rejection of optical noise in underwater imaging systems. In order to assess the effectiveness of these methods, which range from modulation/demodulation to polarimetry, we carried out a series of experiments by using the laboratory prototype of an AM 3D imager ( = 405 nm for marine archaeology surveys, in course of realization at the ENEA Artificial Vision Laboratory (Frascati, Rome. The obtained results confirm the validity of the proposed methods for optical noise rejection.

  12. Techniques for Effective Optical Noise Rejection in Amplitude-Modulated Laser Optical Radars for Underwater Three-Dimensional Imaging

    Directory of Open Access Journals (Sweden)

    R. Ricci

    2010-01-01

    Full Text Available Amplitude-modulated (AM laser imaging is a promising technology for the production of accurate three-dimensional (3D images of submerged scenes. The main challenge is that radiation scattered off water gives rise to a disturbing signal (optical noise that degrades more and more the quality of 3D images for increasing turbidity. In this paper, we summarize a series of theoretical findings, that provide valuable hints for the development of experimental methods enabling a partial rejection of optical noise in underwater imaging systems. In order to assess the effectiveness of these methods, which range from modulation/demodulation to polarimetry, we carried out a series of experiments by using the laboratory prototype of an AM 3D imager (λ = 405 nm for marine archaeology surveys, in course of realization at the ENEA Artificial Vision Laboratory (Frascati, Rome. The obtained results confirm the validity of the proposed methods for optical noise rejection.

  13. High-Temperature Monitoring of Refractory Wall Recession Using Frequency-Modulated Continuous-wave (FM-CW) Radar Techniques

    International Nuclear Information System (INIS)

    Varghese, B.; DeConick, C.; Cartee, G.; Zoughi, R.; Velez, M.; Moore, R.

    2005-01-01

    Furnaces are among the most crucial components in the glass and metallurgical industry. Nowadays, furnaces are being operated at higher temperatures and for longer periods of time thus increasing the rate of wear on the furnace refractory lining. Consequently, there is a great need for a nondestructive tool that can accurately measure refractory wall thickness at high temperatures. In this paper the utility of a frequency-modulated continuous-wave (FM-CW) radar is investigated for this purpose

  14. OX40 ligand expressed in glioblastoma modulates adaptive immunity depending on the microenvironment: a clue for successful immunotherapy.

    Science.gov (United States)

    Shibahara, Ichiyo; Saito, Ryuta; Zhang, Rong; Chonan, Masashi; Shoji, Takuhiro; Kanamori, Masayuki; Sonoda, Yukihiko; Kumabe, Toshihiro; Kanehira, Masahiko; Kikuchi, Toshiaki; So, Takanori; Watanabe, Takashi; Takahashi, Hiroaki; Iwabuchi, Erina; Tanaka, Yuetsu; Shibahara, Yukiko; Sasano, Hironobu; Ishii, Naoto; Tominaga, Teiji

    2015-02-15

    Glioblastoma is the most malignant human brain tumor and has a dismal prognosis; however, some patients show long-term survival. The interaction between the costimulatory molecule OX40 and its ligand OX40L generates key signals for T-cell activation. The augmentation of this interaction enhances antitumor immunity. In this present study, we explored whether OX40 signaling is responsible for antitumor adaptive immunity against glioblastoma and also established therapeutic antiglioma vaccination therapy. Tumor specimens were obtained from patients with primary glioblastoma (n = 110) and grade III glioma (n = 34). Quantitative polymerase chain reaction (PCR), flow cytometry, and immunohistochemistry were used to analyze OX40L expression in human glioblastoma specimens. Functional consequences of OX40 signaling were studied using glioblastoma cell lines, mouse models of glioma, and T cells isolated from human subjects and mice. Cytokine production assay with mouse regulatory T cells was conducted under hypoxic conditions (1.5% O2). OX40L mRNA was expressed in glioblastoma specimens and higher levels were associated with prolonged progression-free survival of patients with glioblastoma, who had undergone gross total resection. In this regard, OX40L protein was expressed in A172 human glioblastoma cells and its expression was induced under hypoxia, which mimics the microenvironment of glioblastoma. Notably, human CD4 T cells were activated when cocultured in anti-CD3-coated plates with A172 cells expressing OX40L, as judged by the increased production of interferon-γ. To confirm the survival advantage of OX40L expression, we then used mouse glioma models. Mice bearing glioma cells forced to express OX40L did not die during the observed period after intracranial transplantation, whereas all mice bearing glioma cells lacking OX40L died. Such a survival benefit of OX40L was not detected in nude mice with an impaired immune system. Moreover, compared with systemic

  15. Adapting risk management and computational intelligence network optimization techniques to improve traffic throughput and tail risk analysis.

    Science.gov (United States)

    2014-04-01

    Risk management techniques are used to analyze fluctuations in uncontrollable variables and keep those fluctuations from impeding : the core function of a system or business. Examples of this are making sure that volatility in copper and aluminum pri...

  16. SU-E-P-15: Technique Factor Modulation and Reference Plane Air Kerma Rates in Response to Simulated Patient Thickness Variations for a Sample of Current Generation Fluoroscopes

    Energy Technology Data Exchange (ETDEWEB)

    Wunderle, K [Cleveland Clinic Foundation, Cleveland, OH& Wayne State University School of Medicine, Detroit, MI (United States); Rakowski, J [Wayne State University School of Medicine, Detroit, MI (United States); Dong, F [Cleveland Clinic Foundation, Cleveland, OH (United States)

    2015-06-15

    Purpose: To evaluate and compare approaches to technique factor modulation and air kerma rates in response to simulated patient thickness variations for four state-of-the-art and one previous-generation interventional fluoroscopes. Methods: A polymethyl methacrylate (PMMA) phantom was used as a tissue surrogate for the purposes of determining fluoroscopic reference plane air kerma rates, kVp, mA, and spectral filtration over a wide range of simulated tissue thicknesses. Data were acquired for each fluoroscopic and acquisition dose curve within a default abdomen or body imaging protocol. Results: The data obtained indicated vendor- and model-specific variations in the approach to technique factor modulation and reference plane air kerma rates across a range of tissue thicknesses. Some vendors have made hardware advances increasing the radiation output capabilities of their fluoroscopes; this was evident in the acquisition air kerma rates. However, in the imaging protocol evaluated, all of the state-of-the-art systems had relatively low air kerma rates in the fluoroscopic low-dose imaging mode as compared to the previous-generation unit. Each of the newest-generation systems also employ copper filtration in the selected protocol in the acquisition mode of imaging; this is a substantial benefit, reducing the skin entrance dose to the patient in the highest dose-rate mode of fluoroscope operation. Conclusion: Understanding how fluoroscopic technique factors are modulated provides insight into the vendor-specific image acquisition approach and provides opportunities to optimize the imaging protocols for clinical practice. The enhanced radiation output capabilities of some of the fluoroscopes may, under specific conditions, may be beneficial; however, these higher output capabilities also have the potential to lead to unnecessarily high dose rates. Therefore, all parties involved in imaging, including the clinical team, medical physicists, and imaging vendors, must work

  17. Quality of life of asthmatic children and adolescents: Portuguese translation, adaptation, and validation of the questionnaire "Pediatric Quality of Life (PedsQL) Asthma Module".

    Science.gov (United States)

    Monteiro, Fernanda Pereira; Solé, Dirceu; Wandalsen, Gustavo

    2017-11-01

    The objectives of the study were to translate, validate, and verify the psychometric properties of the Portuguese version of the instrument "Pediatric Quality of Life Asthma Module" (PedsQL Asthma) culturally adapted for the Brazilian culture. After being translated to Portuguese and being culturally adapted, the questionnaire was answered by 200 asthmatic children and adolescents (aged 2-18) as well as the adults responsible for them. Validation required the use of the following instruments: PedsQL Asthma Children (applied to children and adolescents), PedsQL Asthma Parents (applied to adults responsible for children and adolescents), Pediatric Asthma Quality of Life (PAQLQ), Asthma Control Test (ACT) or Childhood Asthma Control Test (C-ACT), as well as socioeconomic and personal information questionnaires. A group of 45 clinically stable children repeated the questionnaires 15-60 days after answering the first questionnaire. Correlations between the scores of PedsQL Children and PedsQL Parents (r  =  0.67), PedsQL Children and PAQLQ (r  =  0.66), and PedsQL Parents and PAQLQ (r  =  0.64) were moderate and significant. Correlations were higher for men (r  =  0.72) when analyzing the children's and parents' answers to PedsQL according to gender. The 5- to 7-year-old age group had the strongest correlations with PAQLQ (r  =  0.79). Cronbach's alpha coefficient for PedsQL Children and Parents had values of 0.85 and 0.87, respectively. A high concordance was observed in both tests at different times, with kappa values of 0.89 and 0.87 for PedsQL Children and Parents, respectively. The instrument used in this study was considered valid, consistent, and reproducible and has acceptable psychometric properties for the Brazilian population.

  18. A Broadly Adaptive Array of Dose-Constraint Templates for Planning of Intensity-Modulated Radiation Therapy for Advanced T-Stage Nasopharyngeal Carcinoma

    International Nuclear Information System (INIS)

    Chau, R.M.-C.; Leung, S.-F.; Kam, M.K.-M.; Cheung, K.-Y.; Kwan, W.-H.; Yu, K.-H.; Chiu, K.-W.; Cheung, M.L.-M.; Chan, A.T.-C.

    2009-01-01

    Purpose: To develop and validate adaptive dose-constraint templates in intensity-modulated radiotherapy (IMRT) planning for advanced T-stage nasopharyngeal carcinoma (NPC). Method and Materials: Dose-volume histograms of clinically approved plans for 20 patients with advanced T-stage NPC were analyzed, and the pattern of distribution in relation to the degree of overlap between targets and organs at risk (OARs) was explored. An adaptive dose constraint template (ADCT) was developed based on the degree of overlap. Another set of 10 patients with advanced T-stage NPC was selected for validation. Results of the manual arm optimization protocol and the ADCT optimization protocol were compared with respect to dose optimization time, conformity indices, multiple-dose end points, tumor control probability, and normal tissue complication probability. Results: For the ADCT protocol, average time required to achieve an acceptable plan was 9 minutes, with one optimization compared with 94 minutes with more than two optimizations of the manual arm protocol. Target coverage was similar between the manual arm and ADCT plans. A more desirable dose distribution in the region of overlap between planning target volume and OARs was achieved in the ADCT plan. Dose end points of OARs were similar between the manual arm and ADCT plans. Conclusions: With the developed ADCT, IMRT treatment planning becomes more efficient and less dependent on the planner's experience on dose optimization. The developed ADCT is applicable to a wide range of advanced T-stage NPC treatment and has the potential to be applied in a broader context to IMRT planning for other cancer sites

  19. Development and Evaluation of the SUMIT Microcomputer Module Entitled 'Predator Functional Response'.

    Science.gov (United States)

    Shaltz, Mark B.

    An experiment was conducted that compared the teaching effectiveness of a computer assisted instructional module and a lecture-discussion. The module, Predator Functional Response (PFR), was developed as part of the SUMIT (Single-concept User-adaptable Microcomputer-based Instructional Technique) project. A class of 30 students was randomly…

  20. A Software Module for High-Accuracy Calibration of Rings and Cylinders on CMM using Multi-Orientation Techniques (Multi-Step and Reversal methods)

    DEFF Research Database (Denmark)

    Tosello, Guido; De Chiffre, Leonardo

    . The Centre for Geometrical Metrology (CGM) at the Technical University of Denmark takes care of free form measurements, in collaboration with DIMEG, University of Padova, Italy. The present report describes a software module, ROUNDCAL, to be used for high-accuracy calibration of rings and cylinders....... The purpose of the software is to calculate the form error and the least square circle of rings and cylinders by mean of average of pontwise measuring results becoming from so-called multi-orientation techniques (both reversal and multi-step methods) in order to eliminate systematic errors of CMM ....

  1. Frequency Modulated Integrated Cavity Output Spectroscopy: A General Technique for Trace Gas and Isotope Measurements with Unprecedented Sensitivity, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A new technique is proposed for improved trace gas detection and measurement that combines the high absorption depths afforded by mid-infrared Integrated Cavity...

  2. An innovative technique for contrast enhancement of computed tomography images using normalized gamma-corrected contrast-limited adaptive histogram equalization

    Science.gov (United States)

    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.

  3. J-Modulation in ID NMR 1H Spectrum of Taurine and Aspartate Using Spin-Echo Technique

    Science.gov (United States)

    Oturak, Halil; Sağlam, Adnan; Bahçeli, Semiha

    1999-05-01

    This study reports on a theoretical calculation of Hahn's spin-echo experiment in case of a model A2B2 spin system with a strongly coupling character and gives the experimental results of one-dimension 1H high-resolution NMR spectra of taurine and aspartate. The calculated amplitudes of the spin-echoes for two different proton groups of taurine are given. Using results of our calculations for taurine, the computer simulations of J-modulation are implemented. It is shown that the agreement be-tween the experimental and simulated spectra is good.

  4. A Temperature-Hardened Sensor Interface with a 12-Bit Digital Output Using a Novel Pulse Width Modulation Technique

    Directory of Open Access Journals (Sweden)

    Emna Chabchoub

    2018-04-01

    Full Text Available A fully integrated sensor interface for a wide operational temperature range is presented. It translates the sensor signal into a pulse width modulated (PWM signal that is then converted into a 12-bit digital output. The sensor interface is based on a pair of injection locked oscillators used to implement a differential time-domain architecture with low sensitivity to temperature variations. A prototype has been fabricated using a 180 nm partially depleted silicon-on-insulator (SOI technology. Experimental results demonstrate a thermal stability as low as 65 ppm/°C over a large temperature range from −20 °C up to 220 °C.

  5. Glacier and climate changes in the Western Indian Himalayas (Ladakh and Lahul-Spiti): remote sensing, field techniques and adaptation techniques

    Science.gov (United States)

    Racoviteanu, Adina; Williams, Mark

    2010-05-01

    Anecdotal evidence from glacier termini observations in the Himalayas suggest that these glaciers have been in a state of general retreat since the last century, and point to "alarming" rates of retreat in the past decades. Concomitantly, local communities in the Western Himalayas have reported changes in glacier extents, snow cover and weather patterns. In response to "alarming" rates of glacial retreat, some indigenous cultures in the Himalayan area have begun a number of adaptive responses such as meltwater harvesting to construct "artificial" glaciers, which store the water during the dry season. There is urgency in: a) scientifically evaluating whether such practices of glacier regeneration can help provide water in a timely manner and 2) developing glacier datasets to assist such local efforts to ensure water supply in these data-scarce mountainous areas. Here we compare and contrast scientific and indigenous perspectives on spatial patterns of glacier changes in the dry areas of Ladakh (34.10°N and 77.34°E ) and Lahul-Spiti district (31.11°N and 77.15°E ) in the Western Indian Himalaya. A new glacier inventory of Lahul-Spiti was constructed using a combination of data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor with Shuttle Radar Topography Mission (SRTM), GPS field data and ground photography. Glacier changes were quantified by comparison with older ASTER inventory and topographic maps. We present changes reported by local communities and recorded in video, oral testimonies and ground photography. We focus on two indigenous practices of water harvesting for glacier regeneration: a) artificial glaciers and b) kul irrigation systems. Field data of artificial glaciers was acquired at Sabu, Stakmo and Phuktsey glaciers using a differential GPS system. Kul irrigation systems were documented in Spiti valley (Lara and Kibber villages). We will present the results of mapping these water harvesting systems with the goal

  6. Education techniques for lifelong learning: writing multiple-choice questions for continuing medical education activities and self-assessment modules.

    Science.gov (United States)

    Collins, Jannette

    2006-01-01

    The multiple-choice question (MCQ) is the most commonly used type of test item in radiologic graduate medical and continuing medical education examinations. Now that radiologists are participating in the maintenance of certification process, there is an increased need for self-assessment modules that include MCQs and persons with test item-writing skills to develop such modules. Although principles of effective test item writing have been documented, violations of these principles are common in medical education. Guidelines for test construction are related to development of educational objectives, defining levels of learning for each objective, and writing effective MCQs that test that learning. Educational objectives should be written in observable, behavioral terms that allow for an accurate assessment of whether the learner has achieved the objectives. Learning occurs at many levels, from simple recall to problem solving. The educational objectives and the MCQs that accompany them should target all levels of learning appropriate for the given content. Characteristics of effective MCQs can be described in terms of the overall item, the stem, and the options. Flawed MCQs interfere with accurate and meaningful interpretation of test scores and negatively affect student pass rates. Therefore, to develop reliable and valid tests, items must be constructed that are free of such flaws. The article provides an overview of established guidelines for writing effective MCQs, a discussion of writing appropriate educational objectives and MCQs that match those objectives, and a brief review of item analysis. (c) RSNA, 2006.

  7. First- and zero-sound velocity and Fermi liquid parameter F2s in liquid 3He determined by a path length modulation technique

    International Nuclear Information System (INIS)

    Hamot, P.J.; Lee, Y.; Sprague, D.T.

    1995-01-01

    We have measured the velocity of first- and zero-sound in liquid 3 He at 12.6 MHz over the pressure range of 0.6 to 14.5 bar using a path length modulation technique that we have recently developed. From these measurements, the pressure dependent value of the Fermi liquid parameter F 2 s was calculated and found to be larger at low pressure than previously reported. These new values of F 2 s indicate that transverse zero-sound is a propagating mode at all pressures. The new values are important for the interpretation of the frequencies of order parameter collective modes in the superfluid phases. The new acoustic technique permits measurements in regimes of very high attenuation with a sensitivity in phase velocity of about 10 ppm achieved by a feedback arrangement. The sound velocity is thus measured continuously throughout the highly attenuating crossover (ωt ∼ 1) regime, even at the lowest pressures

  8. Cross-cultural adaptation and validation of the Spanish version of the American Academy of Orthopaedic Surgeons-Foot and Ankle Module (AAOS-FAMsp).

    Science.gov (United States)

    González-Sánchez, Manuel; Velasco-Ramos, Esther; Ruiz-Muñoz, Maria; Cuesta-Vargas, Antonio I

    2016-07-06

    The current study performed a cross-cultural adaptation to Spanish and examined the internal and external validation of the AAOS-FAM questionnaire. A direct translation (English to Spanish) and a reverse translation (Spanish to English) were performed by two independent professional native translators. Cronbach's α coefficients were calculated to analyse the internal consistency of the measure. The factor structure and construct validity were analysed after extraction by maximum likelihood (EML); extraction was necessary if the following three requirements were met: accounting for ≥10 % of variance, Eigenvalue >1.0 and a scree plot inflexion point. The standard error of measurement and minimal detectable change 90 (MDC90) were calculated. Criterion validity was calculated by analysing the correlation between the American Academy of Orthopaedic Surgeons-Foot and Ankle Module (Spanish version) (AAOS-FAMsp) and Spanish versions of the questionnaires FFI and FHSQ. Regarding internal consistency, Cronbach's α was 0.877, and in the test-retest analysis, the ICC ranged between 0.899 and 0.942. Error measures were calculated by MDC90 and SEM, which showed values of 3.444 and 1.476 %, respectively. The analysis demonstrated a goodness of fit chi-squared value of 803.166 (p validity, the correlation value with FFIsp was r = 0.837 (p Spanish-speaking individuals into both research and clinical practice.

  9. Tong Luo Jiu Nao ameliorates Aβ1-40-induced cognitive impairment on adaptive behavior learning by modulating ERK/CaMKII/CREB signaling in the hippocampus.

    Science.gov (United States)

    Shi, Zhe; Lu, Cong; Sun, Xiuping; Wang, Qiong; Chen, Shanguang; Li, Yinghui; Qu, Lina; Chen, Lingling; Bu, Lanlan; Liao, Duanfang; Liu, Xinmin

    2015-03-11

    Tong Luo Jiu Nao (TLJN), a modern formula of Chinese medicine extracts on the basis of Traditional Chinese Medicine theory, has been used to treat dementia. The present study aimed to investigate its ameliorating effects on Aβ1-40-induced cognitive impairment in rats using a series of novel reward-directed instrumental learning (RDIL) tasks, and to determine its possible mechanism of action. Rats were pretreated with TLJN extract (0.9 and 1.8 g/kg, p.o.) for 10 daysbefore surgery, and were trained to gain reward reinforcement by lever pressing at the meantime. Thereafter, rats received a bilateral microinjection of Aβ1-40 in CA1 regions of the hippocampus. Cognitive performance was evaluated with the goal directed (higher response ratio) and habit (visual signal discrimination and extinction) learning tasks, as well as on the levels of biochemical parameters and molecules. Our findings first demonstrated that TLJN can improve Aβ1-40-induced amnesia in RDIL via enhancing the comprehension of action-outcome association and the utilization of cue information to guide behavior. Then, its ameliorating effects should attribute to the modulation of ERK/CaMKII/CREB signaling in the hippocampus. TLJN can markedly enhance cognitions of Aβ1-40 microinjection animal model in adaptive behavioral tasks. It has the potential, possibly as complementary and alternative therapy, to prevent and/or delay the deterioration of cognitive impairment in AD.

  10. Advances in radiotherapy techniques and delivery for non-small cell lung cancer: benefits of intensity-modulated radiation therapy, proton therapy, and stereotactic body radiation therapy.

    Science.gov (United States)

    Diwanji, Tejan P; Mohindra, Pranshu; Vyfhuis, Melissa; Snider, James W; Kalavagunta, Chaitanya; Mossahebi, Sina; Yu, Jen; Feigenberg, Steven; Badiyan, Shahed N

    2017-04-01

    The 21st century has seen several paradigm shifts in the treatment of non-small cell lung cancer (NSCLC) in early-stage inoperable disease, definitive locally advanced disease, and the postoperative setting. A key driver in improvement of local disease control has been the significant evolution of radiation therapy techniques in the last three decades, allowing for delivery of definitive radiation doses while limiting exposure of normal tissues. For patients with locally-advanced NSCLC, the advent of volumetric imaging techniques has allowed a shift from 2-dimensional approaches to 3-dimensional conformal radiation therapy (3DCRT). The next generation of 3DCRT, intensity-modulated radiation therapy and volumetric-modulated arc therapy (VMAT), have enabled even more conformal radiation delivery. Clinical evidence has shown that this can improve the quality of life for patients undergoing definitive management of lung cancer. In the early-stage setting, conventional fractionation led to poor outcomes. Evaluation of altered dose fractionation with the previously noted technology advances led to advent of stereotactic body radiation therapy (SBRT). This technique has dramatically improved local control and expanded treatment options for inoperable, early-stage patients. The recent development of proton therapy has opened new avenues for improving conformity and the therapeutic ratio. Evolution of newer proton therapy techniques, such as pencil-beam scanning (PBS), could improve tolerability and possibly allow reexamination of dose escalation. These new progresses, along with significant advances in systemic therapies, have improved survival for lung cancer patients across the spectrum of non-metastatic disease. They have also brought to light new challenges and avenues for further research and improvement.

  11. Intensity modulated radiotherapy (IMRT) for patients of the Brazilian unified health system (SUS): an analysis of 508 treatments two years after the technique implementation

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Harley Francisco de; Trevisan, Felipe Amstalden; Bighetti, Viviane Marques; Guimaraes, Flavio da Silva; Amaral, Leonardo Lira; Barbi, Gustavo Lazaro; Borges, Leandro Federiche; Peria, Fernanda Maris, E-mail: harley@fmrp.usp.br [Universidade de Sao Paulo (FMRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Medicina

    2014-11-15

    Objective: the offering of high-technology radiotherapy to the population assisted by the Brazilian unified health system (SUS) is limited since it is not included in the system’s list of procedures and, many times, because of the insufficient installed capacity and lack of specialized human resources. Thus the access to intensity-modulated radiotherapy (IMRT) is restricted to few centers in Brazil. The present study is aimed at presenting the characteristics of the first 508 cases treated with IMRT during the first years after the technique implementation in a university hospital. Materials and methods: the first consecutive 508 cases of IMRT treatment completed in the period from May/2011 to September/2013 were reviewed. Static multi leaf was the technique employed. Results: amongst 4,233 treated patients, 12.5% were submitted to IMRT. Main indications for the treatment included cancers located in the skull, head and neck and prostate. Intensity modulated radiotherapy was utilized in about 30% of cranial and 50% of prostate treatments. Treatment toxicity was observed in 4% of the patients. Conclusion: because of restricted access to radiotherapy in addition to lack of coverage for the procedure, IMRT indications for SUS patients should be based on institutional clinical protocols, with special attention to the reduction of toxicity. (author)

  12. The transportation network rough description for an adaptive traffic control algorithms by means of video detection technique

    Directory of Open Access Journals (Sweden)

    Jan PIECHA

    2013-01-01

    Full Text Available The contribution discusses a transportation network rough description that corresponds to satisfactory level of an adaptive traffic control algorithms implementation [4], supported by video-detection system. The decision making algorithms have to provide us with not only vehicles’ approach time prediction, at the intersections but also finding possible solution for avoiding critical queues at the intersections. Majority of traditional traffic control systems are based on number of cars recorded by inductive loops, however they do not define any proper occupation states at any traffic lane. The time window indicated for passing the defined number of cars loses the distance gaps visible between the cars on the traffic lane. That is why remarkable part from the defined number of cars will not cross the intersection in the defined green light time. Procedures used for searching an optimal solution using the inductive measurements can, in the majority cases, be undoubtedly noticed as a theoretical analysis only.

  13. Digital Collections Are a Sprint, Not a Marathon: Adapting Scrum Project Management Techniques to Library Digital Initiatives

    Directory of Open Access Journals (Sweden)

    Michael Dulock

    2015-12-01

    Full Text Available This article describes a case study in which a small team from the digital initiatives group and metadata services department at the University of Colorado Boulder (CU-Boulder Libraries conducted a pilot of the Scrum project management framework. The pilot team organized digital initiatives work into short, fixed intervals called sprints—a key component of Scrum. Over a year of working in the modified framework yielded significant improvements to digital collection work, including increased production of digital objects and surrogate records, accelerated publication of digital collections, and an increase in the number of concurrent projects. Adoption of sprints has improved communication and cooperation among participants, reinforced teamwork, and enhanced their ability to adapt to shifting priorities.

  14. Coherent MUSIC technique for range/angle information retrieval: Application to a frequency modulated continuous wave MIMO radar

    NARCIS (Netherlands)

    Belfiori, F.; Rossum, W. van; Hoogeboom, P.

    2014-01-01

    A coherent two-dimensional (2D) multiple signal classification (MUSIC) processing for the simultaneous estimation of angular and range target positions has been presented. A 2D spatial smoothing technique is also introduced to cope with the coherent behaviour of the received echoes, which may result

  15. Residual stress in a laser welded EUROFER blanket module assembly using non-destructive neutron diffraction techniques

    CERN Document Server

    Hughes, D J; Heeley, E L

    2014-01-01

    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.

  16. Beam modulation: A novel ToF-technique for high resolution diffraction at the Beamline for European Materials Engineering Research (BEER)

    Science.gov (United States)

    Rouijaa, M.; Kampmann, R.; Šaroun, J.; Fenske, J.; Beran, P.; Müller, M.; Lukáš, P.; Schreyer, A.

    2018-05-01

    The Beamline for European Materials Engineering Research (BEER) is under construction at the European Spallation Source (ESS) in Lund, Sweden. A basic requirement on BEER is to make best use of the long ESS pulse (2.86 ms) for engineering investigations. High-resolution diffraction, however, demands timing resolution up to 0.1% corresponding to a pulse length down to about 70 μs for the case of thermal neutrons (λ ∼ 1.8 Å). Such timing resolution can be achieved by pulse shaping techniques cutting a short section out of the long pulse, and thus paying for resolution by strong loss of intensity. In contrast to this, BEER proposes a novel operation mode called pulse modulation technique based on a new chopper design, which extracts several short pulses out of the long ESS pulse, and hence leads to a remarkable gain of intensity compared to nowadays existing conventional pulse shaping techniques. The potential of the new technique can be used with full advantage for investigating strains and textures of highly symmetric materials. Due to its instrument design and the high brilliance of the ESS pulse, BEER is expected to become the European flagship for engineering research for strain mapping and texture analysis.

  17. Adaptive swarm cluster-based dynamic multi-objective synthetic minority oversampling technique algorithm for tackling binary imbalanced datasets in biomedical data classification.

    Science.gov (United States)

    Li, Jinyan; Fong, Simon; Sung, Yunsick; Cho, Kyungeun; Wong, Raymond; Wong, Kelvin K L

    2016-01-01

    An imbalanced dataset is defined as a training dataset that has imbalanced proportions of data in both interesting and uninteresting classes. Often in biomedical applications, samples from the stimulating class are rare in a population, such as medical anomalies, positive clinical tests, and particular diseases. Although the target samples in the primitive dataset are small in number, the induction of a classification model over such training data leads to poor prediction performance due to insufficient training from the minority class. In this paper, we use a novel class-balancing method named adaptive swarm cluster-based dynamic multi-objective synthetic minority oversampling technique (ASCB_DmSMOTE) to solve this imbalanced dataset problem, which is common in biomedical applications. The proposed method combines under-sampling and over-sampling into a swarm optimisation algorithm. It adaptively selects suitable parameters for the rebalancing algorithm to find the best solution. Compared with the other versions of the SMOTE algorithm, significant improvements, which include higher accuracy and credibility, are observed with ASCB_DmSMOTE. Our proposed method tactfully combines two rebalancing techniques together. It reasonably re-allocates the majority class in the details and dynamically optimises the two parameters of SMOTE to synthesise a reasonable scale of minority class for each clustered sub-imbalanced dataset. The proposed methods ultimately overcome other conventional methods and attains higher credibility with even greater accuracy of the classification model.

  18. Rate Adaptive OFDMA Communication Systems

    International Nuclear Information System (INIS)

    Abdelhakim, M.M.M.

    2009-01-01

    Due to the varying nature of the wireless channels, adapting the transmission parameters, such as code rate, modulation order and power, in response to the channel variations provides a significant improvement in the system performance. In the OFDM systems, Per-Frame adaptation (PFA) can be employed where the transmission variables are fixed over a given frame and may change from one frame to the other. Subband (tile) loading offers more degrees of adaptation such that each group of carriers (subband) uses the same transmission parameters and different subbands may use different parameters. Changing the code rate for each tile in the same frame, results in transmitting multiple codewords (MCWs) for a single frame. In this thesis a scheme is proposed for adaptively changing the code rate of coded OFDMA systems via changing the puncturing rate within a single codeword (SCW). In the proposed structure, the data is encoded with the lowest available code rate then it is divided among the different tiles where it is punctured adaptively based on some measure of the channel quality for each tile. The proposed scheme is compared against using multiple codewords (MCWs) where the different code rates for the tiles are obtained using separate encoding processes. For bit interleaved coded modulation architecture two novel interleaving methods are proposed, namely the puncturing dependant interleaver (PDI) and interleaved puncturing (IntP), which provide larger interleaving depth. In the PDI method the coded bits with the same rate over different tiles are grouped for interleaving. In IntP structure the interleaving is performed prior to puncturing. The performance of the adaptive puncturing technique is investigated under constant bit rate constraint and variable bit rate. Two different adaptive modulation and coding (AMC) selection methods are examined for variable bit rate adaptive system. The first is a recursive scheme that operates directly on the SNR whereas the second

  19. Dependence of Achievable Plan Quality on Treatment Technique and Planning Goal Refinement: A Head-and-Neck Intensity Modulated Radiation Therapy Application

    International Nuclear Information System (INIS)

    Qi, X. Sharon; Ruan, Dan; Lee, Steve P.; Pham, Andrew; Kupelian, Patrick; Low, Daniel A.; Steinberg, Michael; Demarco, John

    2015-01-01

    Purpose: To develop a practical workflow for retrospectively analyzing target and normal tissue dose–volume endpoints for various intensity modulated radiation therapy (IMRT) delivery techniques; to develop technique-specific planning goals to improve plan consistency and quality when feasible. Methods and Materials: A total of 165 consecutive head-and-neck patients from our patient registry were selected and retrospectively analyzed. All IMRT plans were generated using the same dose–volume guidelines for TomoTherapy (Tomo, Accuray), TrueBeam (TB, Varian) using fixed-field IMRT (TB-IMRT) or RAPIDARC (TB-RAPIDARC), or Siemens Oncor (Siemens-IMRT, Siemens). A MATLAB-based dose–volume extraction and analysis tool was developed to export dosimetric endpoints for each patient. With a fair stratification of patient cohort, the variation of achieved dosimetric endpoints was analyzed among different treatment techniques. Upon identification of statistically significant variations, technique-specific planning goals were derived from dynamically accumulated institutional data. Results: Retrospective analysis showed that although all techniques yielded comparable target coverage, the doses to the critical structures differed. The maximum cord doses were 34.1 ± 2.6, 42.7 ± 2.1, 43.3 ± 2.0, and 45.1 ± 1.6 Gy for Tomo, TB-IMRT, TB-RAPIDARC, and Siemens-IMRT plans, respectively. Analyses of variance showed significant differences for the maximum cord doses but no significant differences for other selected structures among the investigated IMRT delivery techniques. Subsequently, a refined technique-specific dose–volume guideline for maximum cord dose was derived at a confidence level of 95%. The dosimetric plans that failed the refined technique-specific planning goals were reoptimized according to the refined constraints. We observed better cord sparing with minimal variations for the target coverage and other organ at risk sparing for the Tomo cases, and higher

  20. Predictors of the Aspiration Component Success of a Direct Aspiration First Pass Technique (ADAPT) for the Endovascular Treatment of Stroke Reperfusion Strategy in Anterior Circulation Acute Stroke.

    Science.gov (United States)

    Blanc, Raphaël; Redjem, Hocine; Ciccio, Gabriele; Smajda, Stanislas; Desilles, Jean-Philippe; Orng, Eliane; Taylor, Guillaume; Drumez, Elodie; Fahed, Robert; Labreuche, Julien; Mazighi, Mikael; Lapergue, Bertrand; Piotin, Michel

    2017-06-01

    A direct aspiration first pass technique (ADAPT) has been reported to be fast, safe, and effective for the treatment of acute ischemic stroke. The aim of this study is to determine the preoperative factors that affect success of the aspiration component of the technique in ischemic stroke patients with large vessel occlusion in the anterior circulation. We enrolled all 347 consecutive patients with anterior circulation acute ischemic stroke admitted for mechanical thrombectomy at our institution from August 2013 to October 2015 and treated by ADAPT for the endovascular treatment of stroke. Baseline and procedural characteristics, modified thrombolysis in cerebral infarction scores, and 3-month modified Rankin Scale were captured and analyzed. Among the 347 patients (occlusion sites: middle cerebral artery=200, 58%; internal carotid artery Siphon=89, 25%; Tandem=58, 17%), aspiration component led to successful reperfusion (modified thrombolysis in cerebral infarction 2b/3 scores) in 55.6% (193/347 patients), stent retrievers were required in 40%, and a total successful final reperfusion rate of 83% (288/347) was achieved. Overall, procedural complications occurred in 13.3% of patients (48/347). Modified Rankin Scale score of 0 to 2 at 90 days was reported in 45% (144/323). Only 2 factors positively influenced the success of the aspiration component: an isolated middle cerebral artery occlusion ( P stroke onset to clot contact ( P =0.018). In this large retrospective study, ADAPT was shown to be safe and effective for anterior circulation acute ischemic stroke with a final successful reperfusion achieved in 83%. The site of arterial occlusion and delay of the procedure were predictors for reperfusion. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02523261, NCT02678169, and NCT02466893. © 2017 American Heart Association, Inc.

  1. Integrated skin flash planning technique for intensity-modulated radiation therapy for vulvar cancer prevents marginal misses and improves superficial dose coverage.

    Science.gov (United States)

    Dyer, Brandon A; Jenshus, Abriel; Mayadev, Jyoti S

    2018-02-28

    Radiation therapy (RT) plays a definitive role in locally advanced vulvar cancer, and in the adjuvant setting with high risk postoperative features after wide local excision. There is significant morbidity associated with traditional, large RT fields using 2D or 3D techniques, and the use of intensity-modulated radiation therapy (IMRT) in vulvar cancer is increasing. However, there remains a paucity of technical information regarding the prevention of a marginal miss during the treatment planning process. The use of an integrated skin flash (ISF) during RT planning can be used to account for anatomic variation, and intra- and interfraction motion seen during treatment. Herein we present the case of a patient with a T1aN0M0, Stage IA vulva cancer to illustrate the progressive vulvar swelling and lymph edema seen during treatment and retrospectively evaluate the dosimetric effects of using an ISF RT plan vs standard RT planning techniques. Standard planning techniques to treat vulvar cancer patients with IMRT do not sufficiently account for the change in patient anatomy and can lead to a marginal miss. ISF is an RT planning technique that can decrease the risk of a marginal miss and the technique is easily implemented during the planning stages of RT treatment. Furthermore, use of an ISF technique can improve vulvar clinical target volume coverage and plan homogeneity. Based on our experience, and this study, a 2-cm ISF is suggested to account for variations in daily clinical setup and changes in patient anatomy during treatment. Published by Elsevier Inc.

  2. Moderately Escalated Hypofractionated (ChemoRadiotherapy Delivered with Helical Intensity-Modulated Technique in Stage III Unresectable Non-Small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Vittorio eDonato

    2013-11-01

    Full Text Available Purpose To assess clinical outcomes and toxicities in patients with stage III unresectable non-small cell lung cancer (NSCLC treated with a moderately escalated hypofractionated radiotherapy delivered with Helical Intensity-Modulated Technique in combination with sequential or concurrent chemotherapy.Methods and Materials Sixty-one consecutive patients considered non-progressive after 2 cycles of induction chemotherapy were treated with a moderately escalated hypofractionated radiation course of 30 daily fractions of 2.25-2.28 Gy each administered in 6 weeks up to a total dose of 67.5 Gy–68.4 Gy (range, 64.5 Gy–71.3 Gy. Thirty-two received sequential RT after 2 more cycles (total= 4 cycles of chemotherapy, while twenty-nine were treated with concurrent chemo-radiation. The target was considered the gross tumour volume and the clinically proven nodal regions, without elective nodal irradiation. Results With a median follow up of 27 months (range 6 to 40, one-year and 2-year OS rate for all patients was 77% and 53% respectively, with a median survival duration of 18.6 months in the sequential group and 24.1 months in the concomitant group. No Grade ≥ 4 acute and late toxicity was reported. Acute Grade 3 treatment-related pneumonitis was detected in 10% of patients. Two patients, both receiving the concurrent schedule, developed a Grade 3 acute esophagitis. The overall incidence of late Grade 3 lung toxicity was 5%. No patients experienced a Grade 3 late esophageal toxicity.Conclusions A moderately hypofractionated radiation course delivered with a Helical Intensity-Modulated Technique is a feasible treatment option for patients with unresectable locally advanced NSCLC receiving chemotherapy (sequentially or concurrently. Hypofractionated radiotherapy with a dedicated technique allows safely dose escalation, minimizing the effect of tumor repopulation that may occur with prolonged treatment time.

  3. An adaptive dual-optimal path-planning technique for unmanned air vehicles with application to solar-regenerative high altitude long endurance flight

    Science.gov (United States)

    Whitfield, Clifford A.

    2009-12-01

    A multi-objective technique for Unmanned Air Vehicle (UAV) path and trajectory autonomy generation, through task allocation and sensor fusion has been developed. The Dual-Optimal Path-Planning (D-O.P-P.) Technique generates on-line adaptive flight paths for UAVs based on available flight windows and environmental influenced objectives. The environmental influenced optimal condition, known as the driver' determines the condition, within a downstream virtual window of possible vehicle destinations and orientation built from the UAV kinematics. The intermittent results are pursued by a dynamic optimization technique to determine the flight path. This sequential optimization technique is a multi-objective optimization procedure consisting of two goals, without requiring additional information to combine the conflicting objectives into a single-objective. An example case-study and additional applications are developed and the results are discussed; including the application to the field of Solar Regenerative (SR) High Altitude Long Endurance (HALE) UAV flight. Harnessing solar energy has recently been adapted for use on high altitude UAV platforms. An aircraft that uses solar panels and powered by the sun during the day and through the night by SR systems, in principle could sustain flight for weeks or months. The requirements and limitations of solar powered flight were determined. The SR-HALE UAV platform geometry and flight characteristics were selected from an existing aircraft that has demonstrated the capability for sustained flight through flight tests. The goals were to maintain continual Situational Awareness (SA) over a case-study selected Area of Interest (AOI) and existing UAV power and surveillance systems. This was done for still wind and constant wind conditions at altitude along with variations in latitude. The characteristics of solar flux and the dependence on the surface location and orientation were established along with fixed flight maneuvers for

  4. Sliding mode controller gain adaptation and chattering reduction techniques for DSP-based PM DC motor drives

    DEFF Research Database (Denmark)

    Dal, Mehmet; Teodorescu, Remus

    2011-01-01

    simulations. To demonstrate the effectiveness of each method, several experiments were performed on a DSP-based PM DC motor drive system. Then, the newly proposed combinations of these methods were implemented. The hardware implementation results are comparatively presented and discussed....... reduction techniques are investigated, and the effectiveness of chattering suppression for current regulation of PM DC drives is tested. The sampling rate was also examined to determine how it affects the amplitude of chattering. This paper concentrates on various combinations of observer-based methods...

  5. Space-Time Joint Interference Cancellation Using Fuzzy-Inference-Based Adaptive Filtering Techniques in Frequency-Selective Multipath Channels

    Directory of Open Access Journals (Sweden)

    Chen Yu-Fan

    2006-01-01

    Full Text Available An adaptive minimum mean-square error (MMSE array receiver based on the fuzzy-logic recursive least-squares (RLS algorithm is developed for asynchronous DS-CDMA interference suppression in the presence of frequency-selective multipath fading. This receiver employs a fuzzy-logic control mechanism to perform the nonlinear mapping of the squared error and squared error variation, denoted by ( , , into a forgetting factor . For the real-time applicability, a computationally efficient version of the proposed receiver is derived based on the least-mean-square (LMS algorithm using the fuzzy-inference-controlled step-size . This receiver is capable of providing both fast convergence/tracking capability as well as small steady-state misadjustment as compared with conventional LMS- and RLS-based MMSE DS-CDMA receivers. Simulations show that the fuzzy-logic LMS and RLS algorithms outperform, respectively, other variable step-size LMS (VSS-LMS and variable forgetting factor RLS (VFF-RLS algorithms at least 3 dB and 1.5 dB in bit-error-rate (BER for multipath fading channels.

  6. A margin-of-the-day online adaptive intensity-modulated radiotherapy strategy for cervical cancer provides superior treatment accuracy compared to clinically recommended margins: a dosimetric evaluation.

    Science.gov (United States)

    Ahmad, Rozilawati; Bondar, Luiza; Voet, Peter; Mens, Jan-Willem; Quint, Sandra; Dhawtal, Glenn; Heijmen, Ben; Hoogeman, Mischa

    2013-10-01

    To dosimetrically evaluate a margin-of-the-day (MoD) online adaptive intensity-modulated radiotherapy (IMRT) strategy for cervical cancer patients. The strategy is based on a single planning computed tomography (CT) scan and a pretreatment constructed IMRT plan library with incremental clinical target volumes (CTV)-to-planning target volumes (PTV) margins. For 14 patients, 9-10 variable bladder filling CT scans acquired at pretreatment and after 40 Gy were available. Bladder volume variability during the treatment course was recorded by twice-weekly US bladder-volume measurements. A MoD strategy that selects the best IMRT plan of the day from a library of plans with incremental margins in steps of 5 mm was compared with a clinically recommended population-based margin (15 mm). To compare the strategies, for each fraction that had a recorded US bladder-volume measurement, the CT scan with the nearest bladder volume was selected from the pretreatment CT series and from the CT series acquired after 40 Gy. A frequency-weighted average of the dose-volume histograms (DVH) parameters calculated for the two selected CT scans was used to estimate the DVH parameters of the fraction of interest. The 15-mm recommended margin resulted in cervix-uterus underdosage in six of 14 patients. Compared with the 15-mm margin, the MoD strategy resulted in significantly better cervix-uterus coverage (p = 0.008) without a significant difference in the sparing of rectum, bladder, and small bowel. For each patient, 3-8 (median 5) plans were needed in the library of plans for the MoD strategy. The required range of the MoD was 5-45 mm (median 15 mm). Twenty-five percent of all fractions could be treated with a MoD of 5 mm and 81% of all fractions could be treated with a MoD up to 25 mm. Compared with a clinically recommended margin, a simple online adaptive strategy resulted in better cervix-uterus coverage without compromising organs at risk sparing.

  7. Comparative study and clinical implementation of two breathing-adapted radiotherapy techniques: dosimetric benefits for lung cancer treatment

    International Nuclear Information System (INIS)

    Simon, L.; Giraud, P.; Rosenwald, J.C.; Servois, V.

    2006-01-01

    Breathing can lead to organ motions up to several centimeters. For radiotherapy of lung, these motions are generally taken into account by adding a specific margin around the target. Thus, treated volumes are often too large to allow for the high-dose values requested for local control. To manage respiratory motion, deep-inspiration breath-hold technique (DIBH) and gated radiotherapy are starting being used clinically. DIBH consists in asking the patient to perform breath-hold during the treatment and the image acquisition, DIBH level being measured by a spirometer. Gated radiotherapy consists in treating the patient at a certain phase of the free breathing. Linac is synchronized with the motion of a marker' located on the patient chest. Planning images are obtained by a four-dimensional CT (4D-CT) using the same marker. We have assessed the value of these two methods. For lung treatment, compared to a standard treatment, toxicity reduction was mainly due to the lung total volume increase.; It is therefore more significant for breath-hold approach. It is also due to the reduction of safety margins, which is similar for both methods. These two techniques, which have specific advantages and drawbacks, are used routinely at Curie Institute for a large proportion of lung patients, but also for some breast, liver or even Hodgkin disease treatments. (author)

  8. Shoulder strengthening exercises adapted to specific shoulder pathologies can be selected using new simulation techniques: a pilot study.

    Science.gov (United States)

    Charbonnier, Caecilia; Lädermann, Alexandre; Kevelham, Bart; Chagué, Sylvain; Hoffmeyer, Pierre; Holzer, Nicolas

    2018-02-01

    Shoulder strength training exercises represent a major component of rehabilitation protocols designed for conservative or postsurgical management of shoulder pathologies. Numerous methods are described for exercising each shoulder muscle or muscle group. Limited information is available to assess potential deleterious effects of individual methods with respect to specific shoulder pathologies. Thus, the goal of this pilot study was to use a patient-specific 3D measurement technique coupling medical imaging and optical motion capture for evaluation of a set of shoulder strength training exercises regarding glenohumeral, labral and subacromial compression, as well as elongation of the rotator cuff muscles. One volunteer underwent magnetic resonance imaging (MRI) and motion capture of the shoulder. Motion data from the volunteer were recorded during three passive rehabilitation exercises and twenty-nine strengthening exercises targeting eleven of the most frequently trained shoulder muscles or muscle groups and using four different techniques when available. For each exercise, glenohumeral and labral compression, subacromial space height and rotator cuff muscles elongation were measured on the entire range of motion. Significant differences in glenohumeral, subacromial and labral compressions were observed between sets of exercises targeting individual shoulder muscles. Muscle lengths computed by simulation compared to MRI measurements showed differences of 0-5%. This study represents the first screening of shoulder strengthening exercises to identify potential deleterious effects on the shoulder joint. Motion capture combined with medical imaging allows for reliable assessment of glenohumeral, labral and subacromial compression, as well as muscle-tendon elongation during shoulder strength training exercises.

  9. Adaptive ethnography

    DEFF Research Database (Denmark)

    Berth, Mette

    2005-01-01

    This paper focuses on the use of an adaptive ethnography when studying such phenomena as young people's use of mobile media in a learning perspective. Mobile media such as PDAs and mobile phones have a number of affordances which make them potential tools for learning. However, before we begin...... formal and informal learning contexts. The paper also proposes several adaptive methodological techniques for studying young people's interaction with mobiles....

  10. Synchronous Supraglottic and Esophageal Squamous Cell Carcinomas Treated with a Monoisocentric Hybrid Intensity-Modulated Radiation Technique

    Directory of Open Access Journals (Sweden)

    Christian L. Barney

    2018-01-01

    Full Text Available Risk factors for squamous cell carcinomas (SCCs of the head and neck (HN and esophagus are similar. As such, synchronous primary tumors in these areas are not entirely uncommon. Definitive chemoradiation (CRT is standard care for locally advanced HNSCC and is a preferred option for inoperable esophageal SCC. Simultaneous treatment of both primaries with CRT can present technical challenges. We report a case of synchronous supraglottic and esophageal SCC primary tumors, highlighting treatment with a monoisocentric hybrid radiation technique and normal tissue toxicity considerations.

  11. An Ad Hoc Adaptive Hashing Technique forNon-Uniformly Distributed IP Address Lookup in Computer Networks

    Directory of Open Access Journals (Sweden)

    Christopher Martinez

    2007-02-01

    Full Text Available Hashing algorithms long have been widely adopted to design a fast address look-up process which involves a search through a large database to find a record associated with a given key. Hashing algorithms involve transforming a key inside each target data to a hash value hoping that the hashing would render the database a uniform distribution with respect to this new hash value. The close the final distribution is to uniform, the less search time would be required when a query is made. When the database is already key-wise uniformly distributed, any regular hashing algorithm, such as bit-extraction, bit-group XOR, etc., would easily lead to a statistically perfect uniform distribution after the hashing. On the other hand, if records in the database are instead not uniformly distributed as in almost all known practical applications, then even different regular hash functions would lead to very different performance. When the target database has a key with a highly skewed distributed value, performance delivered by regular hashing algorithms usually becomes far from desirable. This paper aims at designing a hashing algorithm to achieve the highest probability in leading to a uniformly distributed hash result from a non-uniformly distributed database. An analytical pre-process on the original database is first performed to extract critical information that would significantly benefit the design of a better hashing algorithm. This process includes sorting on the bits of the key to prioritize the use of them in the XOR hashing sequence, or in simple bit extraction, or even a combination of both. Such an ad hoc hash design is critical to adapting to all real-time situations when there exists a changing (and/or expanding database with an irregular non-uniform distribution. Significant improvement from simulation results is obtained in randomly generated data as well as real data.

  12. New scanning technique using Adaptive Statistical lterative Reconstruction (ASIR) significantly reduced the radiation dose of cardiac CT

    International Nuclear Information System (INIS)

    Tumur, Odgerel; Soon, Kean; Brown, Fraser; Mykytowycz, Marcus

    2013-01-01

    The aims of our study were to evaluate the effect of application of Adaptive Statistical Iterative Reconstruction (ASIR) algorithm on the radiation dose of coronary computed tomography angiography (CCTA) and its effects on image quality of CCTA and to evaluate the effects of various patient and CT scanning factors on the radiation dose of CCTA. This was a retrospective study that included 347 consecutive patients who underwent CCTA at a tertiary university teaching hospital between 1 July 2009 and 20 September 2011. Analysis was performed comparing patient demographics, scan characteristics, radiation dose and image quality in two groups of patients in whom conventional Filtered Back Projection (FBP) or ASIR was used for image reconstruction. There were 238 patients in the FBP group and 109 patients in the ASIR group. There was no difference between the groups in the use of prospective gating, scan length or tube voltage. In ASIR group, significantly lower tube current was used compared with FBP group, 550mA (450–600) vs. 650mA (500–711.25) (median (interquartile range)), respectively, P<0.001. There was 27% effective radiation dose reduction in the ASIR group compared with FBP group, 4.29mSv (2.84–6.02) vs. 5.84mSv (3.88–8.39) (median (interquartile range)), respectively, P<0.001. Although ASIR was associated with increased image noise compared with FBP (39.93±10.22 vs. 37.63±18.79 (mean ±standard deviation), respectively, P<001), it did not affect the signal intensity, signal-to-noise ratio, contrast-to-noise ratio or the diagnostic quality of CCTA. Application of ASIR reduces the radiation dose of CCTA without affecting the image quality.

  13. All-optical virtual private network system in OFDM based long-reach PON using RSOA re-modulation technique

    Science.gov (United States)

    Kim, Chang-Hun; Jung, Sang-Min; Kang, Su-Min; Han, Sang-Kook

    2015-01-01

    We propose an all-optical virtual private network (VPN) system in an orthogonal frequency division multiplexing (OFDM) based long reach PON (LR-PON). In the optical access network field, technologies based on fundamental upstream (U/S) and downstream (D/S) have been actively researched to accommodate explosion of data capacity. However, data transmission among the end users which is arisen from cloud computing, file-sharing and interactive game takes a large weight inside of internet traffic. Moreover, this traffic is predicted to increase more if Internet of Things (IoT) services are activated. In a conventional PON, VPN data is transmitted through ONU-OLT-ONU via U/S and D/S carriers. It leads to waste of bandwidth and energy due to O-E-O conversion in the OLT and round-trip propagation between OLT and remote node (RN). Also, it causes inevitable load to the OLT for electrical buffer, scheduling and routing. The network inefficiency becomes more critical in a LR-PON which has been researched as an effort to reduce CAPEX and OPEX through metro-access consolidation. In the proposed system, the VPN data is separated from conventional U/S and re-modulated on the D/S carrier by using RSOA in the ONUs to avoid bandwidth consumption of U/S and D/S unlike in previously reported system. Moreover, the transmitted VPN data is re-directed to the ONUs by wavelength selective reflector device in the RN without passing through the OLT. Experimental demonstration for the VPN communication system in an OFDM based LR-PON has been verified.

  14. Nasopharyngeal Carcinoma Treated with Precision-Oriented Radiation Therapy Techniques Including Intensity-Modulated Radiotherapy: Preliminary Results

    Directory of Open Access Journals (Sweden)

    Wen-Shan Liu

    2004-02-01

    Full Text Available This paper reports preliminary results with intensity-modulated radiotherapy (IMRT in nasopharyngeal carcinoma (NPC. Between August 2000 and May 2001, we treated 19 patients with NPC using IMRT. Twelve patients had stage I-II disease and seven had stage III-IV disease. Six patients received 9.0-19.8 Gy three-dimensional conformal radiotherapy (3D-CRT before IMRT and 18 patients received a brachytherapy boost after IMRT. The mean follow-up time was 13.0 months. All patients with stage II-IV disease except one received two cycles of chemoradiotherapy with cisplatin and 5-fluorouracil (5-FU during radiotherapy, followed by two to four cycles of chemotherapy after radiotherapy. Tumor response was assessed using clinical examination and computerized tomography or magnetic resonance imaging. The mean doses administered to the gross tumor volume and clinical tumor volume were 70.9 Gy and 63.2 Gy, respectively. The mean doses administered to the right and left parotid glands were 38.1 Gy and 38.6 Gy, respectively. All 19 patients had a complete response of primary and lymph node disease. Grade III mucositis developed during chemoradiotherapy in 15 patients (79%. In addition, clinical grade I xerostomia was recorded in nine patients, grade II in nine, and grade III in one. This study demonstrated that 3D-CRT, IMRT, intracavitary brachytherapy, and chemotherapy are effective and safe methods to treat NPC. Although IMRT treatment spared parotid gland function, its efficacy may be significantly influenced by disease stage and location of the neck lymph nodes. More cases and a longer follow-up to assess survival and complications are planned.

  15. Adaptive parametric model order reduction technique for optimization of vibro-acoustic models: Application to hearing aid design

    DEFF Research Database (Denmark)

    Creixell Mediante, Ester; Jensen, Jakob Søndergaard; Naets, Frank

    2018-01-01

    performance and modelling them accurately requires a precise description of the strong interaction between the light-weight parts and the internal and surrounding air over a wide frequency range. Parametric optimization of the FE model can be used to reduce the vibroacoustic feedback in a device during...... the design phase; however, it requires solving the model iteratively for multiple frequencies at different parameter values, which becomes highly time consuming when the system is large. Parametric Model Order Reduction (pMOR) techniques aim at reducing the computational cost associated with each analysis......-parameter optimization of a frequency response for a hearing aid model, evaluated at 300 frequencies, where the objective function evaluations become more than one order of magnitude faster than for the full system....

  16. Poster — Thur Eve — 67: Tangential Modulated Arc Therapy (TMAT): A Novel Technique using Megavoltage Photons for the Treatment of Superficial Disease

    International Nuclear Information System (INIS)

    Hadsell, M; Xing, L; Bush, K

    2014-01-01

    We propose a new type of treatment that employs a modulated tangential photon field to provide superior coverage of complex superficial targets when compared to other commonly employed methods, and drastically reduce dose to the underlying sensitive structures often present in these cases. TMAT plans were formulated for a set of four representative cases: 1. Scalp sarcoma, 2. Posterior chest-wall sarcoma, 3. Pleural mesothelioma with intact lung, 4. Chest-wall with deep inframammary nodes. For these cases, asymmetric jaw placement, angular limitations, and central isocenter placements were used to force optimization solutions with beam lines tangential to the body surface. When compared with unrestricted modulated arcs, the tangential arc scalp treatment reduced the max and mean doses delivered to the brain by 33Gy (from 55Gy to 22Gy) and 6Gy (from 14Gy to 8Gy), respectively. In the posterior chest wall case, the V10 for the ipsilateral lung was kept below 5% impressively while retaining the 45Gy target prescription coverage by over 97%. For the breast chest-wall case, the TMAT 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. TMAT 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

  17. Poster — Thur Eve — 67: Tangential Modulated Arc Therapy (TMAT): A Novel Technique using Megavoltage Photons for the Treatment of Superficial Disease

    Energy Technology Data Exchange (ETDEWEB)

    Hadsell, M; Xing, L; Bush, K [Department of Radiation Oncology, Stanford University Medical Center (United States)

    2014-08-15

    We propose a new type of treatment that employs a modulated tangential photon field to provide superior coverage of complex superficial targets when compared to other commonly employed methods, and drastically reduce dose to the underlying sensitive structures often present in these cases. TMAT plans were formulated for a set of four representative cases: 1. Scalp sarcoma, 2. Posterior chest-wall sarcoma, 3. Pleural mesothelioma with intact lung, 4. Chest-wall with deep inframammary nodes. For these cases, asymmetric jaw placement, angular limitations, and central isocenter placements were used to force optimization solutions with beam lines tangential to the body surface. When compared with unrestricted modulated arcs, the tangential arc scalp treatment reduced the max and mean doses delivered to the brain by 33Gy (from 55Gy to 22Gy) and 6Gy (from 14Gy to 8Gy), respectively. In the posterior chest wall case, the V10 for the ipsilateral lung was kept below 5% impressively while retaining the 45Gy target prescription coverage by over 97%. For the breast chest-wall case, the TMAT 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. TMAT 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.

  18. Improving mouse controlling and movement for people with Parkinson's disease and involuntary tremor using adaptive path smoothing technique via B-spline.

    Science.gov (United States)

    Hashem, Seyed Yashar Bani; Zin, Nor Azan Mat; Yatim, Noor Faezah Mohd; Ibrahim, Norlinah Mohamed

    2014-01-01

    Many input devices are available for interacting with computers, but the computer mouse is still the most popular device for interaction. People who suffer from involuntary tremor have difficulty using the mouse in the normal way. The target participants of this research were individuals who suffer from Parkinson's disease. Tremor in limbs makes accurate mouse movements impossible or difficult without any assistive technologies to help. This study explores a new assistive technique-adaptive path smoothing via B-spline (APSS)-to enhance mouse controlling based on user's tremor level and type. APSS uses Mean filtering and B-spline to provide a smoothed mouse trajectory. Seven participants who have unwanted tremor evaluated APSS. Results show that APSS is very promising and greatly increases their control of the computer mouse. Result of user acceptance test also shows that user perceived APSS as easy to use. They also believe it to be a useful tool and intend to use it once it is available. Future studies could explore the possibility of integrating APSS with one assistive pointing technique, such as the Bubble cursor or the Sticky target technique, to provide an all in one solution for motor disabled users.

  19. Bioinspired, roughness-induced, water and oil super-philic and super-phobic coatings prepared by adaptable layer-by-layer technique

    Science.gov (United States)

    Brown, Philip S.; Bhushan, Bharat

    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 a durable, functional coating. This technique provides necessary flexibility to improve substrate adhesion combined with desirable surface chemistry. Polyelectrolyte binder, SiO2 nanoparticles, and silane or fluorosurfactant layers are deposited, combining surface roughness and necessary chemistry to result in four different coatings: superhydrophilic/superoleophilic, superhydrophobic/superoleophilic, superhydrophobic/superoleophobic, and superhydrophilic/superoleophobic. The superoleophobic coatings display hexadecane contact angles >150° with tilt angles superhydrophobic coatings display water contact angles >160° with tilt angles hydrophobic properties, whilst others mix and match oil and water repellency and affinity. Coating durability was examined through the use of micro/macrowear experiments. These coatings display transparency acceptable for some applications. Fabrication via this novel combination of techniques results in durable, functional coatings displaying improved performance compared to existing work where either durability or functionality is compromised. PMID:26353971

  20. Impact of the adaptive statistical iterative reconstruction technique on image quality in ultra-low-dose CT

    International Nuclear Information System (INIS)

    Xu, Yan; He, Wen; Chen, Hui; Hu, Zhihai; Li, Juan; Zhang, Tingting

    2013-01-01

    Aim: To evaluate the relationship between different noise indices (NIs) and radiation dose and to compare the effect of different reconstruction algorithm applications for ultra-low-dose chest computed tomography (CT) on image quality improvement and the accuracy of volumetric measurement of ground-glass opacity (GGO) nodules using a phantom study. Materials and methods: A 11 cm thick transverse phantom section with a chest wall, mediastinum, and 14 artificial GGO nodules with known volumes (919.93 ± 64.05 mm 3 ) was constructed. The phantom was scanned on a Discovery CT 750HD scanner with five different NIs (NIs = 20, 30, 40, 50, and 60). All data were reconstructed with a 0.625 mm section thickness using the filtered back-projection (FBP), 50% adaptive statistical iterative reconstruction (ASiR), and Veo model-base iterative reconstruction algorithms. Image noise was measured in six regions of interest (ROIs). Nodule volumes were measured using a commercial volumetric software package. The image quality and the volume measurement errors were analysed. Results: Image noise increased dramatically from 30.7 HU at NI 20 to 122.4 HU at NI 60, with FBP reconstruction. Conversely, Veo reconstruction effectively controlled the noise increase, with an increase from 9.97 HU at NI 20 to only 15.1 HU at NI 60. Image noise at NI 60 with Veo was even lower (50.8%) than that at NI 20 with FBP. The contrast-to-noise ratio (CNR) of Veo at NI 40 was similar to that of FBP at NI 20. All artificial GGO nodules were successfully identified and measured with an average relative volume measurement error with Veo at NI 60 of 4.24%, comparable to a value of 10.41% with FBP at NI 20. At NI 60, the radiation dose was only one-tenth that at NI 20. Conclusion: The Veo reconstruction algorithms very effectively reduced image noise compared with the conventional FBP reconstructions. Using ultra-low-dose CT scanning and Veo reconstruction, GGOs can be detected and quantified with an acceptable