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1

Miyamoto, Naokazu, Kosuke Hirata, Noriko Kimura, and Eri Miyamoto-Mikami. "Contributions of Hamstring Stiffness to Straight-Leg-Raise and Sit-and-Reach Test Scores." International Journal of Sports Medicine 39, no. 02 (November 30, 2017): 110–14. http://dx.doi.org/10.1055/s-0043-117411.

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AbstractThe passive straight-leg-raise (PSLR) and the sit-and-reach (SR) tests have been widely used to assess hamstring extensibility. However, it remains unclear to what extent hamstring stiffness (a measure of material properties) contributes to PSLR and SR test scores. Therefore, we aimed to clarify the relationship between hamstring stiffness and PSLR and SR scores using ultrasound shear wave elastography. Ninety-eight healthy subjects completed the study. Each subject completed PSLR testing, and classic and modified SR testing of the right leg. Muscle shear modulus of the biceps femoris, semitendinosus, and semimembranosus was quantified as an index of muscle stiffness. The relationships between shear modulus of each muscle and PSLR or SR scores were calculated using Pearson’s product-moment correlation coefficients. Shear modulus of the semitendinosus and semimembranosus showed negative correlations with the two PSLR and two SR scores (absolute r value≤0.484). Shear modulus of the biceps femoris was significantly correlated with the PSLR score determined by the examiner and the modified SR score (absolute r value≤0.308). The present findings suggest that PSLR and SR test scores are strongly influenced by factors other than hamstring stiffness and therefore might not accurately evaluate hamstring stiffness.
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2

Rong, Juan, Feifeng Liu, and Yingjie Miao. "Integrated Radar and Communications Waveform Design Based on Multi-Symbol OFDM." Remote Sensing 14, no. 19 (September 21, 2022): 4705. http://dx.doi.org/10.3390/rs14194705.

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Integrated radar and communications (IRC) technology has become very important for civil and military applications in recent years, and IRC waveform design is a major challenge for IRC development. In this paper, we focus on the IRC waveform design based on the multi-symbol orthogonal frequency division multiplexing (OFDM) technique. In view of the defects resulting from high peak-to-mean envelope power ratios (PMEPRs) and high range sidelobes in IRC systems, an intelligent and effective IRC waveform design method jointly optimized with the PMEPR and peak-to-sidelobe ratio (PSLR) is proposed. Firstly, a flexible tone reservation (TR)-based IRC waveform structure is applied in both temporal and frequency domains, i.e. multi-symbol OFDM waveform. Secondly, the optimization problem considering PMEPR and PSLR and extending them to the Lp-norm form is reformulated. Then, the conjugate gradient of the objective function is analytically derived and the conjugate gradient algorithm (CGA) is presented to simultaneously improve the PMEPR and PSLR. Finally, the simulation results show that the proposed algorithm can efficiently generate IRC waveforms with an excellent PMEPR, PSLR, radar signal-to-noise ratio (SNR), and bit error rate (BER) performance.
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3

Muyor, José, Fernando Alacid, and Pedro López-Miñarro. "Influence of Hamstring Muscles Extensibility on Spinal Curvatures and Pelvic Tilt in Highly Trained Cyclists." Journal of Human Kinetics 29, no. 1 (September 1, 2011): 15–23. http://dx.doi.org/10.2478/v10078-011-0035-8.

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Influence of Hamstring Muscles Extensibility on Spinal Curvatures and Pelvic Tilt in Highly Trained CyclistsThe purpose of this study was to determine the influence of hamstring muscles extensibility in standing, maximal trunk flexion with knees extended and on the bicycle in lower handlebar-hands position of highly trained cyclists. Ninety-six cyclists were recruited for the study (mean ± SD, age: 30.36 ± 5.98 years). Sagittal spinal curvatures and pelvic tilt were measured in the standing position, maximal trunk flexion with knees extended (sit-and-reach test) and while sitting on a bicycle in lower handlebar-hand position using a Spinal Mouse system. Hamstring muscles extensibility was determined in both legs by passive straight leg raise test (PSLR). The sample was divided into three groups according to PSLR angle: (1) reduced extensibility (PSLR < 80º; n = 30), (2) moderate hamstring extensibility group (PSLR = 80º; - 90º; n = 35), and (3) high hamstring extensibility (PSLR = > 90º; n = 31). ANOVA analysis showed significant differences among groups for thoracic (p < 0.001) and pelvic tilt (p < 0.001) angles in the sit-andreach test. No differences were found between groups for standing and on the bicycle position. Post hoc analysis showed significant differences in all pairwise comparisons for thoracic angle (p < 0.01) and pelvic angle (p < 0.001) in the sit-and-reach test. No differences were found in lumbar angle in any posture. In conclusion, the hamstring muscles extensibility influence the thoracic and pelvic postures when maximal trunk flexion with knees extended is performed, but not when cyclists are seated on their bicycles
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4

Santonja-Medina, Fernando, Sara Santonja-Renedo, Antonio Cejudo, Francisco Ayala, Vicente Ferrer, Antonio Pastor, Mónica Collazo-Diéguez, Olga Rodríguez-Ferrán, Pilar Andújar, and Pilar Sainz de Baranda. "Straight Leg Raise Test: Influence of Lumbosant© and Assistant Examiner in Hip, Pelvis Tilt and Lumbar Lordosis." Symmetry 12, no. 6 (June 2, 2020): 927. http://dx.doi.org/10.3390/sym12060927.

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The passive straight leg raise (PSLR) test is widely used to assess hamstring extensibility. However, to accurately measure hamstring extensibility throughout PSLR, appropriate stabilization of the pelvis must be provided in order to minimize the possible influence of any compensatory movement in the scores reached. The main purpose of this study was to demonstrate the degree of influence of the Lumbosant© and an assistant examiner in hamstring extensibility in healthy young adults. A secondary objective was to verify the variability of the posterior pelvic tilt movement. Hamstring muscle extensibility was measured using the traditional (only an examiner) and new (using a low-back protection support Lumbosant© and two trained [principal and assistant] examiners) PSLR procedures. Correlation coefficients were expressed using r values, accompanying descriptors and 90% confidence intervals. Variance explained was expressed via the R2 statistic. To examine possible differences, the Mann-Whitney U-test was conducted. Additionally, Cohen’s d was calculated for all results, and the magnitudes of the effect were interpreted and statistical significance set at p < 0.05. A stepwise multiple regression analysis was performed to examine the relationship between scores and values. The final score that was determined with the new PSLR is significantly lower (13° approximately) than the one obtained through the traditional procedure (75.3 ± 14.4° vs. 89.2 ± 20.8°; d = −0.777 [moderate]). The data presented in this study suggest that the PSLR may overestimate hamstring extensibility unless lumbopelvic movement is controlled. Therefore, we recommend the use of Lumbosant© and an auxiliary examiner to obtain more accurate hamstring extensibility scores.
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5

Khan, Waseem, Saleem Shahid, Waleed Iqbal, Ahsan Sarwar Rana, Hijab Zahra, Moath Alathbah, and Syed Muzahir Abbas. "Semi-Coprime Array with Staggered Beam-Steering of Sub-Arrays." Sensors 23, no. 12 (June 10, 2023): 5484. http://dx.doi.org/10.3390/s23125484.

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A split-aperture array (SAA) is an array of sensors or antenna elements in which the array is split into two or more sub-arrays (SAs). Recently proposed SAAs, namely coprime and semi-coprime arrays, offer to attain a small half-power beamwidth (HPBW) with a small number of elements, compared to most conventional unified-aperture arrays, at the cost of reduced peak-to-side-lobe ratio (PSLR). To reduce HPBW and increase PSLR, non-uniform inter-element spacing and excitation amplitudes have proven helpful. However, all the existing arrays and beam-formers suffer increased HPBW, degraded PSLR or both when the main beam is steered away from the broadside. In this paper, we propose staggered beam-steering of SAs, a novel technique for decreasing HPBW. In this technique, we steer the main beams of the SAs of a semi-coprime array to angles slightly different from the desired steering angle. In conjunction with staggered beam-steering of SAs, we have utilized Chebyshev weights to suppress the side lobes. The results show that the beam-widening effect of Chebyshev weights can be mitigated considerably by staggered beam-steering of the SAs. Ultimately, the unified beam-pattern of the whole array offers HPBW and PSLR better than the existing SAAs, uniform and non-uniform linear arrays, especially when the desired steering angle is away from the broadside direction.
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6

Li, Yingsong, Wenxing Li, and Qiubo Ye. "A CPW-Fed Circular Wide-Slot UWB Antenna with Wide Tunable and Flexible Reconfigurable Dual Notch Bands." Scientific World Journal 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/402914.

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A coplanar waveguide (CPW)-fed circular slot antenna with wide tunable dual band-notched function and frequency reconfigurable characteristic is designed, and its performance is verified experimentally for ultra-wideband (UWB) communication applications. The dual band-notched function is achieved by using a T-shaped stepped impedance resonator (T-SIR) inserted inside the circular ring radiation patch and by etching a parallel stub loaded resonator (PSLR) in the CPW transmission line, while the wide tunable bands can be implemented by adjusting the dimensions of the T-SIR and the PSLR. The notch band reconfigurable characteristic is realized by integrating three switches into the T-SIR and the PSLR. The numerical and experimental results show that the proposed antenna has a wide bandwidth ranging from 2.7 GHz to 12 GHz with voltage standing wave ratio (VSWR) less than 2, except for the two notch bands operating at 3.8–5.9 GHz and 7.7–9.2 GHz, respectively. In addition, the proposed antenna has been optimized to a compact size and can provide omnidirectional radiation patterns, which are suitable for UWB communication applications.
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7

Liu, Jin, Wei Wang, and Hongjun Song. "Optimization of Weighting Window Functions for SAR Imaging via QCQP Approach." Sensors 20, no. 2 (January 11, 2020): 419. http://dx.doi.org/10.3390/s20020419.

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Weighting window functions are commonly used in Synthetic Aperture Radar (SAR) imaging to suppress the high Peak SideLobe Ratio (PSLR) at the price of probable Signal-to-Noise Ratio (SNR) loss and mainlobe widening. In this paper, based on the method of designing a mismatched filter, we have proposed a Quadratically Constrained Quadratic Program (QCQP) approach, which is a convex that can be solved efficiently, to optimize the weighting window function with both amplitude and phase, expecting to offer better imaging performance, especially on PSLR, SNR loss, and mainlobe width. According to this approach and its modified form, we are able to design window functions to optimize the PSLR or the SNR loss under different kinds of flexible and practical constraints. Compared to the ordinary real-valued and symmetric window functions, like the Taylor window, the designed window functions are complex-valued and can be asymmetric. By using Synthetic Aperture Radar (SAR) point target imaging simulation, we show that the optimized weighting window function can clearly show the weak target hidden in the sidelobes of the strong target.
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8

Muyor, José. "Validity and Reliability of a New Device (WIMU®) for Measuring Hamstring Muscle Extensibility." International Journal of Sports Medicine 38, no. 09 (July 13, 2017): 691–95. http://dx.doi.org/10.1055/s-0043-108998.

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AbstractThe aims of the current study were 1) to evaluate the validity of the WIMU® system for measuring hamstring muscle extensibility in the passive straight leg raise (PSLR) test using an inclinometer for the criterion and 2) to determine the test-retest reliability of the WIMU® system to measure hamstring muscle extensibility during the PSLR test. 55 subjects were evaluated on 2 separate occasions. Data from a Unilever inclinometer and WIMU® system were collected simultaneously. Intraclass correlation coefficients (ICCs) for the validity were very high (0.983–1); a very low systematic bias (−0.21°–−0.42°), random error (0.05°–0.04°) and standard error of the estimate (0.43°–0.34°) were observed (left–right leg, respectively) between the 2 devices (inclinometer and the WIMU® system). The R2 between the devices was 0.999 (p<0.001) in both the left and right legs. The test-retest reliability of the WIMU® system was excellent, with ICCs ranging from 0.972–0.995, low coefficients of variation (0.01%), and a low standard error of the estimate (0.19–0.31°). The WIMU® system showed strong concurrent validity and excellent test-retest reliability for the evaluation of hamstring muscle extensibility in the PSLR test.
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9

Li, Cong, Weimin Bao, Luping Xu, Hua Zhang, and Ziyang Huang. "Radar Communication Integrated Waveform Design Based on OFDM and Circular Shift Sequence." Mathematical Problems in Engineering 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/9840172.

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Based on the orthogonal frequency division multiplexing (OFDM) technique, an intelligent waveform is designed, which is suitable for simultaneously performing data transmission and radar sensing. In view of the inherent high peak-to-mean envelope power ratio (PMERP) and poor peak-to-side-lobe ratio (PSLR) problems in the OFDM based radar and communication (RadCom) waveform design, we propose two technologies to deal with that. To be specific, we adopt Gray code technology to reduce the PMERP and simultaneously choose an optimal cyclic sequence to improve the PSLR of RadCom waveform. In our method, the optimal cyclic sequence is dynamically generated to continuously provide the best waveform according to the change of communication data. In addition, to meet the requirements of different radar detection tasks, two simple methods are utilized to adjust the bandwidth of RadCom waveform. To verify the advantages of the designed waveform, we conduct several simulation experiments to compare with some existing RadCom waveforms. The results show that our designed RadCom waveform can simultaneously achieve lower PMERP and higher PSLR. In addition, our designed RadCom waveform has a thumbtack type fuzzy function and shows the good ability to do multitarget detection.
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10

El_Mashade, Mohamed Bakry, Haithem Akah, and Shimaa Abd El-Monem. "Windowing Accuracy Evaluation for PSLR Enhancement of SAR Image Recovery." Advances in Science, Technology and Engineering Systems Journal 5, no. 1 (January 2020): 48–57. http://dx.doi.org/10.25046/aj050107.

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11

Rabiee, N., H. Azad, and N. Parhizgar. "Exploiting Chirp Rate Estimation Methods to Improve Image Formation Quality of Synthetic Aperture Radar." International Journal of Aerospace Engineering 2021 (September 28, 2021): 1–13. http://dx.doi.org/10.1155/2021/6636286.

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A common assumption in SAR image formation and processing algorithms is that the chirp rates of the transmitted and received radar signals are exactly the same. Dechirp processing is also done based on this common assumption. In real scenarios, the chirp rate of the received signal is different from that of the transmitted signal due to several reasons. In case the difference between the chirp rates of the transmitted and received signals is obvious, the demodulation and compression of the received pulse are not carried out precisely and defocusing the targets and the output images of the SAR processor results. In the present paper, a new technique is proposed to improve the image formation quality of SAR by exploiting chirp rate estimation methods. Based on the proposed technique, the chirp rate of the received signal is estimated, and then, dechirp is carried out by using a time-reversed complex conjugate filter constructed based on the estimated chirp rate. In this stage, the existing chirp rate estimation algorithms can be used. The quality of the output image is assessed using PSLR as a quantitative criterion and the average number of point target extension pixels along the azimuth direction. Simulation results indicated that the smaller the average number of point target extension pixels along with azimuth and the higher the PSLR average is, the better the output image quality would be. Therefore, output images obtained from the proposed method by exploiting chirp rate estimation algorithms would have a better quality with a higher PSLR average (14.1 and 13.6) and also the lower average number of point target extension pixels along the azimuth directions (2.1 and 4.9) than the common method with PSLR average (8.3) and an average number of point target extension pixels along the azimuth direction (7.1).
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12

Riaz, Syeda Anum, and Muhammad Usman. "EFFECT OF STATIC STRETCHING OF HAMSTRING ON NON-SPECIFIC LOW BACK PAIN." Pakistan Journal of Rehabilitation 12, no. 1 (January 4, 2023): 41–48. http://dx.doi.org/10.36283/pjr.zu.12.1/007.

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Objective: To determine the effect of static stretching of hamstring muscle on the non-specific low back pain. Methodology: A Quasi-Experimental study was conducted in Rabia Moon Institute of Neurology which total 30 participants were included through non-probability purposive sampling. Thirty participants were selected who fulfilled our inclusion criteria, they were divided into two groups; group A or treatment group received conventional physiotherapy treatment as well a static stretching exercise protocol for 5 days. Group B or control group received conventional physiotherapy treatment only. VAS (Visual analog scale) and Oswestry Disability questionnaire, SFGD (Standing Finger to ground Distance,) PSLR (passive straight leg raise) for both legs were measured pre- and post-treatment. Result: A total of 30 patients aged 20-55 were included in the study. Mean age of the participants was found to be 37.88 years. The difference in means of all the assessment parameters pre and post-treatment for both groups were analyzed through paired t-test. There was a significant improvement in VAS, SFGD, Passive Straight leg Raise PSLR (right leg), PSLR (left leg) and level of disability pre- and post-treatment in the treatment group. Conclusion: This present study concluded that static stretching of hamstrings is effective in decreasing non-specific low back pain.
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13

Kim, Young Kyun, Sung Yeon Cho, and Kun Ho Lee. "Effects of transcutaneous electrical nerve stimulation and instrument-assisted soft tissue mobilization combined treatment on chronic low back pain: A randomized controlled trial." Journal of Back and Musculoskeletal Rehabilitation 34, no. 5 (September 6, 2021): 895–902. http://dx.doi.org/10.3233/bmr-200369.

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BACKGROUND: Transcutaneous electrical nerve stimulation (TENS) for chronic low back pain (CLBP) requires a treatment period of ⩾ 6 weeks to decrease pain and disability and is ineffective as sole treatment. Instrument-assisted soft tissue mobilization (IASTM) has rapid effects in musculoskeletal disorders. OBJECTIVE: This study aimed to investigate the effects of a 3-week combined TENS and IASTM treatment (TICT) on CLBP. METHODS: Thirty-two young men with CLBP were randomly divided into the TICT and control groups (n= 16 each). Patients were evaluated with the visual analog (VAS) and face pain-rating scales (FPRS) for pain, the Oswestry Disability Index (ODI) and passive straight leg raise (PSLR) test for flexibility, and the supine bridge test (SBT) for endurance before and after the treatment course. The TICT group received TICT on the lower back, glutes, and hamstrings, six times in 3 weeks. RESULTS: Group, time, and group × time interaction effects on pain were significant (VAS and FPRS, all p< 0.001). Group × time interaction (ODI, p< 0.001; PSLR, p< 0.05; SBT, p< 0.01) and group (ODI, p< 0.05) and time main effects (ODI, p< 0.001; PSLR, p< 0.01; SBT, p< 0.001) on motor function were significant. CONCLUSION: Thus, short-term TICT decreased pain level and increased motor function in CLBP patients, yet further investigation is needed on different age and gender groups.
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14

Muyor, José M., and Francisco M. Arrabal-Campos. "Effects of Acute Fatigue of the Hip Flexor Muscles on Hamstring Muscle Extensibility." Journal of Human Kinetics 53, no. 1 (December 1, 2016): 23–31. http://dx.doi.org/10.1515/hukin-2016-0007.

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AbstractThe purpose of the present study was to evaluate the influence of acute fatigue of the hip flexor muscles on scores attained in tests frequently used in literature to measure hamstring muscle extensibility, namely the passive straight leg raise (PSLR), active straight leg raise (ASLR), passive knee extension (PKE), active knee extension (AKE), sit-and-reach (SR) and toe-touch (TT) tests. A total of seventy-five healthy and recreationally active adults voluntarily participated in this study. To reach fatigue, the participants actively lifted their legs alternately as many times as possible. In the passive tests, the results were 7.10 ± 5.21° and 5.68 ± 4.54° higher (p < 0.01) for PSLR and PKE tests, respectively, after acute fatigue. However, in the ASLR test, the results were lower post-fatigue than pre-fatigue (mean difference = -5.30° ± 9.51°; p < 0.01). The AKE, SR and TT tests did not show significant differences between pre- and post-fatigue (p > 0.05). Moderate (r = 0.40) to high (r = 0.97) correlation coefficients were found, which were statistically significant among all the measured flexibility tests both pre- and post-fatigue. In conclusion, the active implication of the hip flexor muscles until reaching fatigue had acute influences on the results of the PSLR, PKE and ASLR tests, but not on the results of the AKE, SR and TT tests. It is recommended to use the AKE test to assess hamstring muscle extensibility in situations where athletes show fatigue in their hip flexor muscles.
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15

Chukka, Anoosha, and B. T. Krishna. "Peak Side Lobe Reduction analysis of NLFM and Improved NLFM Radar signal." AIUB Journal of Science and Engineering (AJSE) 21, no. 2 (November 23, 2022): 125–31. http://dx.doi.org/10.53799/ajse.v21i2.440.

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Signal design is an important component for good performance of radar systems. Here, the problem of determining a good radar signal with the objective of minimizing autocorrelation sidelobes is addressed. Linear Frequency Modulated signal (LFM) is frequently used pulse compression waveform. But using LFM makes it necessary to use weighting techniques in order to reduce the side lobes which considerably decrease the SNR. At the radar receiver, the LFM signal results in first side lobe of -13dB corresponding to the main lobe. This may reduce the resultant SNR usually by 1 or 2dB. In this paper, an attempt is done to design a radar signal to attain low autocorrelation Peak Side Lobe Ratio (PSLR) which exhibits high SNR and high range resolution. In order to maintain high SNR and to get suppressed side lobes of the signal, one can use Non-Linear Frequency Modulation (NLFM). A NLFM signal is designed for different time sweeps called as Improved NLFM. In Improved NLFM the total time sweep and bandwidth are divided into Two Stage and Tri-Stage sweeps NLFM. The quality of the overall best radar signal is assessed through the parameter PSLR for different values of BT. From this analysis, it is found that the tri stage NLFM gives the low PSLR up to -17.62dB. Simulation results shows the reduction in the sidelobe level from LFM to NLFM and in Improved two and Tri-Stage NLFM.
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16

Pérez-Vigo, C., M. A. Sanchez-Lastra, O. Martínez-de-Quel, and C. Ayan. "Fiabilidad y validez de las pruebas v-sit-and-reach y toe-touch en preescolares." Revista Internacional de Medicina y Ciencias de la Actividad Física y del Deporte 22, no. 88 (December 10, 2022): 969–84. http://dx.doi.org/10.15366/rimcafd2022.88.015.

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Este estudio de carácter psicométrico tuvo como objetivo evaluar la fiabilidad y validez de las pruebas V-Sit and Reach (VS) y Toe –Touch (TT) en población preescolar. De un total inicial de 158 participantes, 132 realizaron las pruebas en tres ocasiones. La prueba de elevación pasiva de la pierna recta (PSLR) se usó como indicador de validez. Ambas pruebas mostraron una fiabilidad excelente (CCI=0,91-0,93 para el VS; CCI=0,93-0,97 para el TT). Se observaron correlaciones estadísticamente significativas (p<0,05) entre ambas herramientas y la prueba de PSLR para todos los grupos analizados, excepto en el TT en el grupo de 3 años de edad. En conclusión, estos hallazgos indican que tanto el VS como el TT son pruebas con una validez moderada para evaluar la flexibilidad de la parte inferior del cuerpo en preescolares. La prueba VS puede ser preferible sobre la prueba TT.
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Weber, Patrick, Werner Klingler, Robert Schleip, Nadine Weber, and Christine Joisten. "The Influence of a Single Instrument-Assisted Manual Therapy (IAMT) for the Lower Back on the Structural and Functional Properties of the Dorsal Myofascial Chain in Female Soccer Players: A Randomised, Placebo-Controlled Trial." Journal of Clinical Medicine 11, no. 23 (November 30, 2022): 7110. http://dx.doi.org/10.3390/jcm11237110.

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Background: Instrument-assisted manual therapy (IAMT) is indicated to improve flexibility, reduce pain, and induce hyperaemia locally and along myofascial chains. The underlying effects are largely unclear. This randomised, placebo-controlled pilot study aimed to gain first insights into these effects, primarily on the structural level, through ultrasonography. Methods: 67 healthy female soccer players aged 20.9 (±3.9) years were examined after right lumbar intervention (IAMT: intervention group (IG), heat application: comparison group (CG), pressure-less placebo: placebo group (PG)). Ultrasonography (absolute movement and shear motion), flexibility tests (passive straight leg raise test (PSLR), lumbar and thoracic double inclinometry), and superficial skin temperature were recorded before (t0), immediately (t1) and 45 min after the intervention (t2). Results: IAMT decreased the absolute mobility of the superficial lamina and its shear motion to the superficial fascia compared with the PG (t1; p < 0.05). PSLR improved in the IG compared with the CG (t2) and PG (t1, t2; p < 0.05). The temperature increased in the IG and CG compared with the PG (t1, t2) and in the CG compared with the IG (t1; p < 0.05). Conclusion: IAMT of the lumbar back briefly reduces absolute mobility of the superficial lamina and its shear motion to the superficial fascia, improves flexibility, and increases the temperature.
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18

Kavitha, Chandu. "Optimization of two-stage NLFM signal using Heuristic approach." Indian Journal of Science and Technology 13, no. 44 (November 20, 2020): 4465–73. http://dx.doi.org/10.17485/ijst/v13i44.1841.

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Background/Objectives: The design of appropriate Non-Linear Frequency Modulation (NLFM) signals continues to be the focus of research in radar pulse compression theory for sidelobe reduction. This study focuses on a heuristic design and optimization algorithm to optimize the side lobe values of the NLFM signal designed using two-piece wise linear frequency modulation (LFM) functions. Methods: 1) Heuristic search identifies the optimum B1, T1, and B2, T2, which yield the lowest sidelobe value of the designed function.2) Compute all the side lobe values of the designed NLFM signal using an algorithm developed in Python scripting language. To plot a complete contour map for all the calculated side lobe values, which helps identify the associated variations in the range of side lobe values. Finally, optimize the side lobe values keeping the main lobe width and time-bandwidth (BT) product unchanged by designing a dynamic optimization algorithm. Findings: The algorithm developed considered all side lobe levels after the main lobe for optimization. The focus is mainly on the peak sidelobe ratio (PSLR) value without affecting the other parameters. The results demonstrate that the achieved side lobes exhibit their desired levels. Novelty: The method is useful in all types of hardware associated with weather radar applications to military solutions. The technique can be extended to other multistage signals consisting of piecewise linear Segments. Keywords: Contour; LFM; NLFM; optimization; PSLR
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Li, Xiaoyu, Shuai Wang, Wei Chen, Zhi Weng, Weiqiang Fan, and Zijian Tian. "An Intelligent Vision-Based Tracking Method for Underground Human Using Infrared Videos." Symmetry 14, no. 8 (August 22, 2022): 1750. http://dx.doi.org/10.3390/sym14081750.

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The underground mine environment is dangerous and harsh, tracking and detecting humans based on computer vision is of great significance for mine safety monitoring, which will also greatly facilitate identification of humans using the symmetrical image features of human organs. However, existing methods have difficulty solving the problems of accurate identification of humans and background, unstable human appearance characteristics, and humans occluded or lost. For these reasons, an improved aberrance repressed correlation filter (IARCF) tracker for human tracking in underground mines based on infrared videos is proposed. Firstly, the preprocess operations of edge sharpening, contrast adjustment, and denoising are used to enhance the image features of original videos. Secondly, the response map characteristics of peak shape and peak to side lobe ratio (PSLR) are analyzed to identify abnormal human locations in each frame, and the method of calculating the image similarity by generating virtual tracking boxes is used to accurately relocate the human. Finally, using the value of PSLR and the highest peak point of the response map, the appearance model is adaptively updated to further improve the robustness of the tracker. Experimental results show that the average precision and success rate of the IARCF tracker in the five underground scenarios reach 0.8985 and 0.7183, respectively, and the improvement of human tracking in difficult scenes is excellent. The IARCF tracker can effectively track underground human targets, especially occluded humans in complex scenes.
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Sabaria, Sabaria, and Syahfrizal Tahcfulloh. "Range and Velocity Resolution of Linear- Frequency-Modulated Signals on Subarray-Mimo Radar." Jurnal ELTIKOM 7, no. 2 (February 2, 2024): 200–209. http://dx.doi.org/10.31961/eltikom.v7i2.940.

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The most important radar system performance is determining the range-velocity of the detected target. This performance is obtained from processing an ambiguity-function (AF) between signals from target reflections and radar radiation signals. Selection of the appropriate waveform transmitted by the radar is a key factor in supporting high resolution radar performance in the AF. There are many waveforms that have been studied in radar systems, especially for multi-antenna radars, i.e., subarray-MIMO (SMIMO) radar which can form phased array (PA) and MIMO radars simultaneously, in the form of linear-frequency-modulated (LFM) signals. In this paper, we examine the use of LFM waveforms combined with SMIMO radar to produce plots of three-dimensional AF as a function of time delay and Doppler shift. The results of the comparison with the Hadamard signal determine the effectiveness of the observed AF performance on parameters such as magnitude, range-velocity resolution, peak sidelobe level ratio, and integrated sidelobe ratio by taking into account the factors of the number of Tx antennas on the PA radar and the number of Tx subarrays on the MIMO radar. The evaluation results of the SMIMO radar configuration (M = 6) with the number of Tx-Rx antenna elements the being 8 provide the best mainlobe magnitude, sidelobe magnitude, range resolution, velocity resolution, PSLR, and ISLR of AF LFM signals compared to conventional radars are 235.2dB, 7.54dB, 37.5m, 75km/s, 29.89dB, and 29.8dB, respectively. Meanwhile, the LFM signal is far superior to the Hadamard signal which has PSLR and ISLR 1.16dB and -3.36dB, respectively.
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Drozdowicz, Jedrzej, and Piotr Samczynski. "Drone-Based 3D Synthetic Aperture Radar Imaging with Trajectory Optimization." Sensors 22, no. 18 (September 15, 2022): 6990. http://dx.doi.org/10.3390/s22186990.

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This paper presents a trajectory determination and optimization method of multirotors equipped with a single-channel radar to obtain 3D Synthetic Aperture Radar imaging. The result is a realistic trajectory that allows to obtain an imaging of the assumed quality in less time than using a multi-pass trajectory. The optimization criteria, in addition to the cross-range resolution, are the Peak Sidelobe Ratio (PSLR), Integrated Sidelobe Ratio (ISLR), and time of flight. The algorithm is based on a realistic motion model of the radar platform. This paper presents all the steps of the algorithm and provides simulation results that show its practical applicability. The advantage of the presented approach over the existing ones is indicated and further research directions are proposed.
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Ye, Ming Kun, Qin Zhu, Peng Cheng Dai, and Jun Tang. "Design of QAM-OFDM Radar-Communication Integrated Signal Based on Golay Complementary sequences." Journal of Physics: Conference Series 2085, no. 1 (November 1, 2021): 012010. http://dx.doi.org/10.1088/1742-6596/2085/1/012010.

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Abstract The integration of radar and communication is conducive to improving the utilization rate of hardware resources and spectrum. To address the issue that the communication information in orthogonal frequency division multiplexing (OFDM) integrated signal for radar and communication affects detection performance, an OFDM integrated signal for radar and communication based on precoding was proposed. The communication information of the integrated signal was pre-coded by using the Gray Complementary Sequences (GCS) with better correlation performance to improve the performance of the ambiguity function of the integrated signal and its detection ability. Simulation results show that GCS have better correlation performance compared to M and Gold sequences, and the OFDM integrated signal pre-coded by GCS has lower Peak Sidelobes Ratio (PSLR) and comparable radar performance to LFM.
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Shen, Wei, Xiaofeng Chen, Yong Zhang, Xin Hu, Jian Wu, Lijun Liu, Chuanlu Deng, Chengyong Hu, and Yi Huang. "A Concise and Adaptive Sidelobe Suppression Algorithm Based on LMS Filter for Pulse-Compressed Signal of Φ-OTDR." Photonics 11, no. 1 (January 8, 2024): 70. http://dx.doi.org/10.3390/photonics11010070.

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A concise and adaptive sidelobe suppression algorithm based on a least mean square (LMS) filter is proposed for pulse-compressed signals of a phase-sensitive optical time-domain reflectometer (Φ-OTDR) system. The algorithm is suitable for the denoising filtering process of phase coding OTDR (PC-OTDR) systems and mitigates the sidelobe effect due to matched filtering. In a simulation experiment, Rayleigh backscattering (RBS) signals including phase-coded pulse signals are generated and decoded to verify that the LMS algorithm can eliminate the sidelobes more effectively than the windowing method and the recursive least squares (RLS) method. Then, the PC-OTDR system is set up and combined with the LMS algorithm for positioning experiments. The results show that the peak side lobe ratio (PSLR) of the signals can reach −15.86 dB, which is 4.26 dB lower than the raw pulse compressed signal.
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Vaquero-Cristóbal, Raquel, Patricia Molina-Castillo, Pedro A. López-Miñarro, Mario Albaladejo-Saura, and Francisco Esparza-Ros. "Hamstring extensibility differences among elite adolescent and young dancers of different dance styles and non-dancers." PeerJ 8 (May 26, 2020): e9237. http://dx.doi.org/10.7717/peerj.9237.

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Background Hamstrings have been analyzed extensively due to their tendency to shorten and their effect in the lumbo-pelvic dynamics and the sagittal position of the spine in trunk flexion with extended knees positions. It has been demonstrated that practicing a certain sport results in long-term changes in hamstring extensibility. Despite this, adequate extensibility of the hamstring musculature is essential for the dancer’s performance. Several studies have found differences in the extensibility of the hamstrings depending on the dance style, but none have compared ballet, Spanish dance and modern dance. The purpose of the present research was to analyze the differences in hamstring extensibility among professional dance students based on dance style practiced and non-dancers. Methods The sample was comprised of 210 students from the Professional Dance Conservatory (70 for ballet, 70 for Spanish dance and 70 for modern dance) and 70 non-dancers. For the assessment of hamstring extensibility, the angle in the passive and active straight leg raise (PSLR and ASLR, respectively) test, and the scores of the pelvic tilt in sit-and-reach (SR) test and the toe-touch (TT) test were randomly conducted. Results The results showed significant differences for all the tests according to group (p < 0.001). In the PSLR and ASLR test, for both legs, and in the pelvic tilt in the SR test, the ballet dancers showed greater ranges of hamstring extensibility than the modern dancers and Spanish dancers (p ≤ 0.001). In the distance in the SR test and in the pelvic tilt in the TT test, the ballet dancers obtained higher values than the Spanish dancers (p = 0.004 and p = 0.003, respectively). The modern dancers showed higher ranges of hip flexion than the Spanish dancers in the ASLR test for both legs and in the pelvic tilt in the SR test (p from 0.007 to <0.001). Dancers showed significantly higher hamstring extensibility than non-dancers in all the tests (p < 0.001). Conclusions The systematic practice of dance, regardless of the style, seems to lead to high ranges of hamstring extensibility. Ballet dancers have the greatest hamstring extensibility.
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Kausar, Sumaira, M. Younus Javed, Samabia Tehsin, and Almas Anjum. "A Novel Mathematical Modeling and Parameterization for Sign Language Classification." International Journal of Pattern Recognition and Artificial Intelligence 30, no. 05 (April 21, 2016): 1650009. http://dx.doi.org/10.1142/s0218001416500099.

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Sign language recognition (SLR) has got wide applicability. SLR system is considered to be a challenging one. This paper presents empirical analysis of different mathematical models for Pakistan SLR (PSLR). The proposed method is using the parameterization of sign signature. Each sign is represented with a mathematical function and then coefficients of these functions are used as the feature vector. This approach is based on exhaustive experimentation and analysis for getting the best suitable mathematical representation for each sign. This extensive empirical analysis, results in a very small feature vector and hence to a very efficient system. The robust proposed method has got general applicability as it just need a new training set and it can work equally good for any other dataset. Sign set used is quite complex in the sense that intersign similarity distance is very small but even then proposed methodology has given quite promising results.
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Zheng, Jian, Ping Chu, Xiaoye Wang, and Zhaocheng Yang. "Inner-Frame Time Division Multiplexing Waveform Design of Integrated Sensing and Communication in 5G NR System." Sensors 23, no. 15 (August 1, 2023): 6855. http://dx.doi.org/10.3390/s23156855.

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The design of an integrated sensing and communication (ISAC) waveform compatible with the 5G new radio (NR) system is crucial in enabling ISAC by utilizing the hardware of existing base stations (BSs). In this paper, we design an inner-frame time division multiplexed sensing waveform in the frame structure of 5G NR to achieve ISAC. The designed waveform is computed by the simulated annealing algorithm on an optimization cost function of a constrained combination of the peak-to-sidelobe ratio (PSLR) and the integrated sidelobe ratio (ISLR) of the velocity ambiguity function. Specifically, the constraints are the 5G communication protocol and 5G NR frame structure. In addition, we conducted corresponding signal detection and estimation methods to illustrate the performance of the sensing waveform. Both theoretical analysis and simulation experiments show that the designed waveform can effectively achieve target detection and parameter estimation under low sensing cost conditions.
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Washington, Richard, Dmitriy Garmatyuk, Saba Mudaliar, and Ram M. Narayanan. "Many-Objective RadarCom Signal Design via NSGA-II Genetic Algorithm Implementation and Simulation Analysis." Remote Sensing 14, no. 15 (August 6, 2022): 3787. http://dx.doi.org/10.3390/rs14153787.

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In this communication, we investigate the performance of the Non-dominated Sorting Genetic Algorithm II (NSGA-II) in many-objective optimization scenarios pertaining to joint radar and communication functionality. We introduce five objectives relevant to sensing and secure communications and develop a cost function where these objectives can be individually prioritized by a user. We consider three scenarios: Radar Priority, Communication Priority, and All (Objectives) Equal; we then demonstrate the optimization results using an orthogonal frequency-division multiplexing (OFDM) radarcom signal. The objectives with selected weights are shown to improve system performance and thereby validate the viability of our approach. The Radar Priority scenario showed the best improvement in probability of detection, PSLR, and PAPR. Compared to the baseline performance values, the improvements were: from 94.05% to 96%, from 11.7 to 13.6 dB, and from 9.46 to 7.09 dB, respectively. The communication scenario saw the best improvement in BER and clutter similarity (measured by NRMSE) from 3.52% to 0.39% and 0.87 to 0.59, respectively.
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Liang, Can, Yanhua Wang, Zhuxi Yang, Xueyao Hu, Qiubo Pei, Wei Gu, and Liang Zhang. "Cooperative Automotive Radars with Multi-Aperture Multiplexing MIMO Sparse Array Design." Electronics 11, no. 8 (April 9, 2022): 1198. http://dx.doi.org/10.3390/electronics11081198.

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In this paper, a multi-aperture multiplexing multiple-input multiple-output (MAM-MIMO) sparse array is presented for cooperative automotive radars (CARs). The proposed sparse array composed of multiple subarrays can simultaneously cover a wide field-of-view (FOV) and achieve the required azimuth resolution at different ranges. To validate this idea, an optimization model for the MAM-MIMO sparse array is derived based on the example of CARs. This optimization model has been found by combining the peak-to-sidelobe ratio (PSLR) at all beams pointing within the constraints of different detection ranges. In addition, a hierarchical genetic algorithm based on the multi-objective decomposition method has been developed to obtain the optimized sparse array. The proposed method has been evaluated through both simulations and experiments. It is demonstrated that the optimized MAM-MIMO sparse array can effectively suppress sidelobes of its subarrays, yet with reasonably high azimuth resolutions and large FOVs.
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Manap, Mustafa, Abdul Rahim Abdullah, Srete Nikolovski, Tole Sutikno, and Mohd Hatta Jopri. "An improved smooth-windowed Wigner-Ville distribution analysis for voltage variation signal." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 5 (October 1, 2020): 4982. http://dx.doi.org/10.11591/ijece.v10i5.pp4982-4991.

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This paper outlines research conducted using bilinear time-frequency distribution (TFD), a smooth-windowed wigner-ville distribution (SWWVD) used to represent time-varying signals in time-frequency representation (TFR). Good time and frequency resolutions offer superiority in SWWVD to analyze voltage variation signals that consist of variations in magnitude. The separable kernel parameters are estimated from the signal in order to get an accurate TFR. The TFR for various kernel parameters is compared by a set of performance measures. The evaluation shows that different kernel settings are required for different signal parameters. Verification of the TFD that operated at optimal kernel parameters is then conducted. SWWVD exhibits a good performance of TFR which gives high peak-to-side lobe ratio (PSLR) and signal-to-cross-terms ratio (SCR) accompanied by low main-lobe width (MLW) and absolute percentage error (APE). This proved that the technique is appropriate for voltage variation signal analysis and it essential for development in an advanced embedded system.
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Lemrabet, Sanae, Maria El Qazoui, Lalla Meryem Idrissi Azzouzi, Ahmed Rguig, Malika Elhamdaoui, Abdelkarim Filali-Maltouf, Leila Medraoui, and Hicham Oumzil. "Evaluation of the Acute Flaccid Paralysis Virological Surveillance System in Polio-Free Morocco, 2010–2018." Advances in Public Health 2022 (September 23, 2022): 1–6. http://dx.doi.org/10.1155/2022/2729937.

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Background. The goal of Acute flaccid paralysis (AFP) surveillance is to comprehensively investigate and report any case of a child below 15 years with a floppy weakness. This is essential for the poliovirus eradication initiative. Objective. In this study, we analyzed the results of nine-year surveillance (2010–2018) of AFP in Morocco. Method. This was a descriptive, retrospective study of cases with AFP routinely documented at the National Referral Laboratory of Polio (NRLP) from 2010 to 2018. Results. Among the 884 AFP cases identified and analyzed, we identified 11 polioviruses as Sabin-like vaccine strains (PSL). PSL were isolated in 11 samples of AFP cases received at the laboratory, including one PSL1, three PSL2 + PSL3, one PSL1 + PSL2, and one PSL1 + 2 + 3. The annualized nonpolio AFP rate per 100,000 children under 15 years ranged from 0.84 during 2011–2015 to 2.29 in 2018. The stool adequacy indicator was poor and may be improved with better delivery times and maintaining the cold chain. The incidence of isolated nonpolio enteroviruses (NPEV) varied between 2.27% and 12.6%, with the average not exceeding 6.35%; the incidence remained low compared to the indicator set by the World Health Organization (WHO). Conclusion. Morocco was certified polio-free by WHO in 2015, and since then no cases of wild poliovirus have been reported. Overall, although the nonpolio AFP rate has risen to the WHO standard, stool adequacy and the proportion of nonpolio enteroviruses need to be improved. The laboratory can adopt alternative techniques, independent of cell culture, to ensure that imported cases of poliovirus are not missed, especially in this era of eradication.
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Giroto de Oliveira, Lucas, Theresa Antes, Benjamin Nuss, Elizabeth Bekker, Akanksha Bhutani, Axel Diewald, Mohamad Basim Alabd, Yueheng Li, Mario Pauli, and Thomas Zwick. "Doppler Shift Tolerance of Typical Pseudorandom Binary Sequences in PMCW Radar." Sensors 22, no. 9 (April 22, 2022): 3212. http://dx.doi.org/10.3390/s22093212.

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In the context of all-digital radar systems, phase-modulated continuous wave (PMCW) based on pseudorandom binary sequences (PRBSs) appears to be a prominent candidate modulation scheme for applications such as autonomous driving. Among the reasons for its candidacy are its simplified transmitter architecture and lower linearity requirements (e.g., compared to orthogonal-frequency division multiplexing radars), as well as its high velocity unambiguity and multiple-input multiple-output operation capability, all of which are characteristic of digital radars. For appropriate operation of a PMCW radar, choosing a PRBS whose periodic autocorrelation function (PACF) has low sidelobes and high robustness to Doppler shifts is paramount. In this sense, this article performs an analysis of Doppler shift tolerance of the PACFs of typically adopted PRBSs in PMCW radar systems supported by simulation and measurement results. To accurately measure the Doppler-shift-induced degradation of PACFs, peak power loss ratio (PPLR), peak sidelobe level ratio (PSLR), and integrated-sidelobe level ratio (ISLR) were used as metrics. Furthermore, to account for effects on targets whose ranges are not multiples of the range resolution, oversampled PACFs are analyzed.
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Samrat, Nahidul Hoque, Joel B. Johnson, Simon White, Mani Naiker, and Philip Brown. "A Rapid Non-Destructive Hyperspectral Imaging Data Model for the Prediction of Pungent Constituents in Dried Ginger." Foods 11, no. 5 (February 23, 2022): 649. http://dx.doi.org/10.3390/foods11050649.

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Ginger is best known for its aromatic odour, spicy flavour and health-benefiting properties. Its flavour is derived primarily from two compound classes (gingerols and shogaols), with the overall quality of the product depending on the interaction between these compounds. Consequently, a robust method for determining the ratio of these compounds would be beneficial for quality control purposes. This study investigated the feasibility of using hyperspectral imaging to rapidly determine the ratio of 6-gingerol to 6-shogoal in dried ginger powder. Furthermore, the performance of several pre-processing methods and two multivariate models was explored. The best-performing models used partial least squares regression (PSLR) and least absolute shrinkage and selection operator (LASSO), using multiplicative scatter correction (MSC) and second derivative Savitzky–Golay (2D-SG) pre-processing. Using the full range of wavelengths (~400–1000 nm), the performance was similar for PLSR (R2 ≥ 0.73, RMSE ≤ 0.29, and RPD ≥ 1.92) and LASSO models (R2 ≥ 0.73, RMSE ≤ 0.29, and RPD ≥ 1.94). These results suggest that hyperspectral imaging combined with chemometric modelling may potentially be used as a rapid, non-destructive method for the prediction of gingerol-to-shogaol ratios in powdered ginger samples.
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Yu, Junfei, Jingwen Li, Bing Sun, Jie Chen, and Chunsheng Li. "Multiclass Radio Frequency Interference Detection and Suppression for SAR Based on the Single Shot MultiBox Detector." Sensors 18, no. 11 (November 19, 2018): 4034. http://dx.doi.org/10.3390/s18114034.

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Radio frequency interference (RFI) is known to jam synthetic aperture radar (SAR) measurements, severely degrading the SAR imaging quality. The suppression of RFI in SAR echo signals is usually an underdetermined blind source separation problem. In this paper, we propose a novel method for multiclass RFI detection and suppression based on the single shot multibox detector (SSD). First, an echo-interference dataset is established by randomly combining the target signal with various types of RFI in a simulation, and the time–frequency form of the dataset is obtained by utilizing the short-time Fourier transform (STFT). Next, the time–frequency dataset acts as input data to train the SSD and obtain a network that is capable of detecting, identifying and estimating the interference. Finally, all of the interference signals are exactly reconstructed based on the prediction results of the SSD and mitigated by an adaptive filter. The proposed method can effectively increase the signal-to-interference-noise ratio (SINR) of RFI-contaminated SAR echoes and improve the peak sidelobe ratio (PSLR) after pulse compression. The simulated experimental results validate the effectiveness of the proposed method.
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Gao, Anqi, Bing Sun, Mengyuan Yan, Chen Xue, and Jingwen Li. "Modified Auto-Focusing Algorithm for High Squint Diving SAR Imaging Based on the Back-Projection Algorithm with Spectrum Alignment and Truncation." Remote Sensing 15, no. 12 (June 7, 2023): 2976. http://dx.doi.org/10.3390/rs15122976.

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The study focuses on addressing the image defocusing issue caused by motion errors in highly squinted Synthetic Aperture Radar (SAR). The traditional auto-focusing algorithm, Phase Gradient Autofocus (PGA), is not effective in this mode due to difficulties in estimating the phase gradient accurately from strong point targets. Two main reasons contribute to this problem. Firstly, the direction of the energy-distributed lines in the Point Spread Function (PSF) does not align with the image’s azimuth direction in highly squinted mode. Secondly, the wavenumber spectrum of high squint SAR images obtained using the Back-Projection Algorithm (BPA) varies spatially, causing aliasing in the azimuth spectrum of all targets. In this paper, a new auto-focusing method is proposed for highly squinted SAR imaging. The modifications to the BP imaging grids have been implemented to address the first problem, while a novel wavenumber spectrum shifting and truncation method is proposed to accurately extract the phase gradient and tackle the spatial variation issue. The feasibility of the proposed algorithm is verified through simulations with point targets and processing of real data. The evaluation of the image shows an average improvement of four times in PSLR (Peak-Sidelobe-to-Noise Ratio).
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Sakr, M., A. S. Amein, F. M. Ahmed, G. M. Amer, and A. Youssef. "Enhanced range-doppler algorithm for SAR image formation." Journal of Physics: Conference Series 2616, no. 1 (November 1, 2023): 012033. http://dx.doi.org/10.1088/1742-6596/2616/1/012033.

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Abstract A Synthetic Aperture Radar (SAR) system is a powerful source of information due to its capability to operate day and night and in all weather conditions. It is essential for military and civilian purposes. Pulse-focusing is employed by the SAR system for achieving both long-range detection and fine-range resolution. The Range-Doppler Algorithm (RDA) is the most popular pulse-focusing technique for creating images from coherent SAR data. Pulse compression techniques for SAR signal processing targets seek to improve map resolution, lower peak power, and increase the Signal-to-Noise Ratio (SNR) of the detected object. This paper demonstrates an enhanced RDA algorithm that uses a modified pulse compression technique based on mismatched filter optimization where Quadratic Constrained Quadratic Program (QCQP) is used. The performance evaluation of the proposed method is performed using visual assessment and the standard image quality metrics peak-side-lobe-ratio (PSLR), impulse-response-width (IRW), and integrated-side-lobe-ratio (ISLR). Simulated and real SAR raw data are used for performance evaluation. The experimental results demonstrate the proposed method’s robustness, efficiency, and reliability in providing a higher-quality SAR image than the traditional RDA algorithm.
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Blanco, M., J. Coello, H. Iturriaga, S. Maspoch, and C. de la Pezuela. "Calibration in near Infrared Diffuse Reflectance Spectroscopy. A Comparative Study of Various Methods." Journal of Near Infrared Spectroscopy 5, no. 2 (March 1997): 67–75. http://dx.doi.org/10.1255/jnirs.100.

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The results obtained by implementing Principal Component Regression (PCR) according to three different criteria for choosing principal components (PCs), and those provided by Partial Least-Squares Regression (PSLR), in the determination of the active compound in a pharmaceutical preparation by near infrared diffuse reflectance spectroscopy are compared. The PCR-top down criterion used is commonly implemented in commercially available software: it selects consecutive PCs beginning with that possessing the largest eigenvalue. The other two criteria used do not assume the PCs with the largest eigenvalues to be the best predictors for the response variable; rather, the PCR-correlation criterion chooses only those PCs exhibiting the highest correlation with the response variable, and the PCR-best subset criterion selects those that provide the lowest predicted residual sum of squares ( PRESS) for an external prediction set. All the calibration methods tested exhibited a similar predictive ability (prediction errors ranged from 1.34% to 1.49%); however, the number of PCs used in the regression varied among them. The PLSR technique did not excel the methods based on selecting the best PCs for regression. Also, the PCR-correlation and PCR-best subset methods provided the same results and used fewer PCs than the PCR-top down method.
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Liu, Shuyi, Yan Jia, Yongqing Liu, and Xiangkun Zhang. "Research on Ultra-Wideband NLFM Waveform Synthesis and Grating Lobe Suppression." Sensors 22, no. 24 (December 14, 2022): 9829. http://dx.doi.org/10.3390/s22249829.

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Ultra-wideband (UWB) nonlinear frequency modulation (NLFM) waveforms have the advantages of low sidelobes and high resolution. By extending the frequency domain wideband synthesis method to the NLFM waveform, the synthetic bandwidth will be limited, and the grating lobe will grow as the number of subpulses increases at a fixed synthetic bandwidth. Aiming for the highly periodic grating lobes caused by equally spaced splicing and small subpulse time-bandwidth products (TxBW), a multisubpulse UWB NLFM waveform synthesis method is proposed in this paper. Random frequency hopping and spectral correction are utilized to disperse the energy of periodic grating lobes and optimize the matched filter of the subpulse, thereby reducing notches and Fresnel ripples in the synthesized spectrum. The results of the hardware-in-the-loop simulation experiment show that the peak sidelobe ratio (PSLR) and the integral sidelobe ratio (ISLR) of the NLFM synthetic wideband waveform (SWW) obtained by 50 subpulses with a bandwidth of 36 MHz are improved by 4.8 dBs and 4.5 dBs, respectively, when compared to the frequency domain wideband synthesis method, and that the grating lobe is suppressed by an average of 10.6 dBs. It also performs well in terms of point target resolution, and it has potential for 2D radar super-resolution imaging.
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Nekoee, M., and J. Amini. "USING A PULSE INTEGRATION TECHNIQUE FOR IMPROVEMENT OF RECEIVED SIGNAL POWER IN GROUND BASED SAR SYSTEM." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W18 (October 18, 2019): 815–19. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w18-815-2019.

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Abstract. Today, radar imaging with synthetic aperture has obtained an important place in radar remote sensing, in such a way that it is utilized in the variety of space borne, airborne and ground platforms to extract information from different desired surfaces. Among these, Ground Based Synthetic Aperture Radars (GB-SAR) has numerous applications such as space system calibration, change detection, target detection, surface displacement determination and condition monitoring. In general, in GB-SAR systems, given that the power of the transmitted signal is low, the received signal is also of low power, and subsequently the presence of target in the image is of lower probability. Therefore, in this research, a method is proposed to increase the received signal power based on pulse integration by a non-Coherent method which results in an increase in the Signal to Noise Ratio (SNR), thereby increasing the focusing power on the target. In this way, a large number of samples can be received in the data collection section and the gain can be therefore increased by integrating the number of received pulses. According to the −3.22 dB Improvement of focusing evaluation criterion (PSLR), it is shown in this research that the accuracy of the target detection is increased. Finally, the effect of the number of pulses integrated on the noise presence and accuracy of the target detection is described.
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Xi, Zirui, Chongdi Duan, Weihua Zuo, Caipin Li, Tonglong Huo, Dongtao Li, and He Wen. "Focus Improvement of Spaceborne-Missile Bistatic SAR Data Using the Modified NLCS Algorithm Based on the Method of Series Reversion." Remote Sensing 14, no. 22 (November 15, 2022): 5770. http://dx.doi.org/10.3390/rs14225770.

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The speed and direction of a missile shifts sharply in the dive phase, making the azimuth frequency modulation (FM) rate change with the azimuthal position, leading to azimuth ambiguities and image distortion. To solve this problem, a modified nonlinear chirp scaling (NLCS) algorithm was adopted to compensate for the azimuth FM rate. First, the geometric configuration and echo signal model of the spaceborne missile bistatic synthetic aperture radar (SAR) were built, and then the Doppler frequency correction was performed, and the 2-D spectrum of the signal was derived by the method of series reversion. Next, range migration correction and range compression were finished in the 2-D frequency domain. Following this, a modified NLCS algorithm was proposed to solve the space variance of Doppler phase problem. After compensating for the azimuth FM rate, the azimuth compression focusing was completed and the imaging result was obtained. Finally, by comparing the calculation amount, imaging effect, and performance index with the traditional NLCS algorithm, it can be concluded that the algorithm reduced the calculation amount by 1.0128 × 108 floating point operations per second (FLOPs) compared with the traditional NLCS algorithm, and the azimuth focusing effect of the edge point was greatly improved. Its resolution, peak sidelobe ratio (PSLR), and integrated sidelobe ratio (ISLR) were improved by 0.87 m, 3.32 dB, and 1.79 dB, respectively, which proved the effectiveness and feasibility of this method.
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Singh, Amit K., J. B. Singh, Bappa Das, Ramesh Singh, Avijit Ghosh, and S. R. Kantwa. "Evaluation of machine learning models for prediction of daily reference evapotranspiration in semi-arid India." Range Management and Agroforestry 44, no. 01 (June 25, 2023): 118–25. http://dx.doi.org/10.59515/rma.2023.v44.i1.14.

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Reference evapotranspiration (ET ) is controlled by climatic factors; hence, its estimation provides an idea 0 about the atmospheric demand of water. Machine learning techniques like elastic net (ELNET), K-nearest neighbours (KNN), multivariate adaptive regression splines (MARS), partial least squares regression (PSLR), random forest (RF), support vector regression (SVR), XGBoost and cubist were employed to predict daily reference evapotranspiration based on daily weather parameters of twenty years. Penman-Monteith method was used as the reference method for ET estimation. All models performed well during calibration showing 0 higher coefficient of determination (R2) which ranged from 0.97 (for PLSR) to 1 (for cubist models). Mean absolute error during calibration ranges from 0.027 mm d-1 for cubist to 0.607 mm d-1 for ELNET. Cubist model (R2 = 1, MAE = 0.017 mm d-1, RMSE = 0.027 mm d-1) outperformed other models during the calibration. During validation, the coefficient of determination (R2) for the machine learning models varied from 0.819 to 1, RMSE varied from 0.06 to 0.60 mm d-1 and MAE varied from 0.031 to 0.38 mm d-1. Based on statistical parameters, best performance was observed for cubist model (R2 = 1, RMSE = 0.06 mm d-1, MAE = 0.031 mm d-1) among the studied machine learning models for the prediction of reference evapotranspiration. Hence, the cubist model may be used to estimate daily reference evapotranspiration for the studied region.
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Wang, Yang, Yunhe Cao, Tat-Soon Yeo, Yuanhao Cheng, and Yulin Zhang. "Sparse Reconstruction-Based Joint Signal Processing for MIMO-OFDM-IM Integrated Radar and Communication Systems." Remote Sensing 16, no. 10 (May 16, 2024): 1773. http://dx.doi.org/10.3390/rs16101773.

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Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) technology is widely used in integrated radar and communication systems (IRCSs). Moreover, index modulation (IM) is a reliable OFDM transmission scheme in the field of communication, which transmits information by arranging several distinguishable constellations. In this paper, we propose a sparse reconstruction-based joint signal processing scheme for integrated MIMO-OFDM-IM systems. Combining the advantages of MIMO and OFDM-IM technologies, the integrated MIMO-OFDM-IM signal design is realized through the reasonable allocation of bits and subcarriers, resulting in better intercarrier interference (ICI) resistance and a higher transmission efficiency. Taking advantage of the sparseness of OFDM-IM, an improved target parameter estimation method based on sparse signal reconstruction is explored to eliminate the influence of empty subcarriers on the matched filtering at the receiver side. In addition, an improved sequential Monte Carlo signal detection method is introduced to realize the efficient detection of communication signals. The simulation results show that the proposed integrated system is 5 dB lower in the peak sidelobe ratio (PSLR) and 1.5 ×105 lower in the number of complex multiplications than the latest MIMO-OFDM system and can achieve almost the same parameter estimation performance. With the same spectral efficiency, it has a lower bit error rate (BER) than existing methods.
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42

Khosravi, Bahman, Behnam Khosravi, and Oskouei Dalili. "On recognition by prime graph of the projective special linear group over GF(3)." Publications de l'Institut Math?matique (Belgrade) 95, no. 109 (2014): 255–66. http://dx.doi.org/10.2298/pim1409255k.

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Let G be a finite group. The prime graph of G is denoted by ?(G). We prove that the simple group PSLn(3), where n ? 9, is quasirecognizable by prime graph; i.e., if G is a finite group such that ?(G) = ?(PSLn(3)), then G has a unique nonabelian composition factor isomorphic to PSLn(3). Darafsheh proved in 2010 that if p > 3 is a prime number, then the projective special linear group PSLp(3) is at most 2-recognizable by spectrum. As a consequence of our result we prove that if n ? 9, then PSLn(3) is at most 2-recognizable by spectrum.
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43

Dong, X. T., X. J. Yue, Y. H. Zhao, and C. M. Han. "RESEARCH ON AIRBORNE SAR IMAGING BASED ON ESC ALGORITHM." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W7 (September 13, 2017): 601–4. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w7-601-2017.

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Due to the ability of flexible, accurate, and fast obtaining abundant information, airborne SAR is significant in the field of Earth Observation and many other applications. Optimally the flight paths are straight lines, but in reality it is not the case since some portion of deviation from the ideal path is impossible to avoid. A small disturbance from the ideal line will have a major effect on the signal phase, dramatically deteriorating the quality of SAR images and data. Therefore, to get accurate echo information and radar images, it is essential to measure and compensate for nonlinear motion of antenna trajectories. By means of compensating each flying trajectory to its reference track, MOCO method corrects linear phase error and quadratic phase error caused by nonlinear antenna trajectories. Position and Orientation System (POS) data is applied to acquiring accuracy motion attitudes and spatial positions of antenna phase centre (APC). In this paper, extend chirp scaling algorithm (ECS) is used to deal with echo data of airborne SAR. An experiment is done using VV-Polarization raw data of C-band airborne SAR. The quality evaluations of compensated SAR images and uncompensated SAR images are done in the experiment. The former always performs better than the latter. After MOCO processing, azimuth ambiguity is declined, peak side lobe ratio (PSLR) effectively improves and the resolution of images is improved obviously. The result shows the validity and operability of the imaging process for airborne SAR.
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44

Azouz, Ahmed, Ashraf Abosekeen, Sameh Nassar, and Mohamed Hanafy. "Design and Implementation of an Enhanced Matched Filter for Sidelobe Reduction of Pulsed Linear Frequency Modulation Radar." Sensors 21, no. 11 (June 1, 2021): 3835. http://dx.doi.org/10.3390/s21113835.

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Pulse compression techniques are commonly used in linear frequency modulated (LFM) waveforms to improve the signal-to-noise ratios (SNRs) and range resolutions of pulsed radars, whose detection capabilities are affected by the sidelobes. In this study, a sidelobe reduction filter (SRF) was designed and implemented using software defined radio (SDR). An enhanced matched filter (EMF) that combines a matched filter (MF) and an SRF is proposed and was implemented. In contrast to the current commonly used approaches, the mathematical model of the SRF frequency response is extracted without depending on any iteration methods or adaptive techniques, which results in increased efficiency and computational speed for the developed model. The performance of the proposed EMF was verified through the measurement of four metrics, including the peak sidelobe ratio (PSLR), the impulse response width (IRW), the mainlobe loss ratio (MLR), and the receiver operational characteristics (ROCs) at different SNRs. The ambiguity function was then used to characterize the Doppler effect on the designed EMF. In addition, the detection of single and multiple targets using the proposed EMF was performed, and the results showed that it overcame the masking problem due to its effective reduction of the sidelobes. Hence, the practical application of the EMF matches the performance analysis. Moreover, when implementing the EMF proposed in this paper, it outperformed the common MF, especially when detecting targets moving at low speeds and having small radar cross-sections (RCS), even under severe masking conditions.
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45

Ramakrishna, Tejaswini Rama Bangalore, Daniel Patrick Killeen, Tim David Nalder, Susan Nellette Marshall, Wenrong Yang, and Colin James Barrow. "Quantifying Graphene Oxide Reduction Using Spectroscopic Techniques: A Chemometric Analysis." Applied Spectroscopy 72, no. 12 (September 10, 2018): 1764–73. http://dx.doi.org/10.1177/0003702818798405.

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The surface chemistry of graphene oxide (GO) can be modified by the chemical reduction of oxygen-containing groups using L-ascorbic acid (L-AA). Being able to “tune” the surface hydrophobicity of GO in a controlled manner, with a well-defined level of reduction, provides a valuable tool for understanding and controlling interactions with hydrophobic surfaces. Numerous analytical and chemical methods have been used to determine the extent of reduction in chemically reduced graphene oxide (CRGO) samples. However, many of these methods are limited by their laborious nature, cost, or lack of sensitivity in resolving oxygen content in samples that have only been reduced for short periods of time, making them inappropriate for rapid use with multiple samples. Here, we have used ultraviolet (UV), Raman, and attenuated total reflection infrared (ATR-IR) spectroscopy to monitor the chemical reduction of GO. These three techniques are simple, rapid, nondestructive, accurate, and widely available. The data set from each technique has been correlated and modeled against a reference data set (carbon to oxygen ratio obtained from elemental analysis) using partial least squares regression (PSLR). Using this approach, the chemical reduction of GO was quantified from UV (r2 = 0.983, RMSECV = 0.049), Raman (r2 = 0.961, RMSECV = 0.073) and ATR-IR (r2 = 0.993, RMSECV = 0.032) data. ATR-IR enabled identification of the different oxygen-containing groups on GO, and coupled with chemometric modeling, provides an excellent approach for the routine quantitative analysis of the chemical reduction of GO.
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46

Wilczyński, Bartosz, Łukasz Radzimiński, Agnieszka Sobierajska-Rek, and Katarzyna Zorena. "Association between Selected Screening Tests and Knee Alignment in Single-Leg Tasks among Young Football Players." International Journal of Environmental Research and Public Health 19, no. 11 (May 31, 2022): 6719. http://dx.doi.org/10.3390/ijerph19116719.

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This study aimed to examine the relationship between knee valgus in the frontal plane projection angle (FPPA) during single-leg squat (SLS), single-leg landing (SLL), and other selected clinical tests in young athletes. Forty-three young healthy elite football players (age: 13.2 (1.7) years) that were regularly training in a local sports club participated in the study. The FPPA was assessed using 2D video analysis. The screening tests included the passive single-leg raise (PSLR), hip external and internal rotation (hip ER and IR), sit and reach test, weight-bearing lunge test (WBLT), modified star excursion balance test (mSEBT), countermovement jump (CMJ), single-leg hop for distance (SLHD), and age peak height velocity (APHV). There was a significant positive relationship between the knee valgus angles in the SLS test and the sit and reach test (r = 0.34) and a negative relationship with the hip ER ROM (r = −0.34) (p < 0.05). The knee valgus angles in the SLL were negatively associated with the hip IR (r = −0.32) and ER ROM (r = −0.34) and positive associated with the WBLT (r = 0.35) and sit and reach test (r = 0.33) (p < 0.05). Linear regression analysis showed that the results of the hip ER ROM and sit and reach tests were independent predictors of the FPPA in the SLS test (r2 = 0.11, p = 0.03 and r2 = 0.12, p = 0.02, respectively). The conducted study showed that individuals with more hip range of motion, more spine flexion extensibility, and less ankle dorsiflexion ROM may be more likely to experience high degrees of knee valgus in FPPA.
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47

Zhu, Chenchen, Pengfei He, Shie Wu, and Guorui Wang. "An Integrated Orthogonal Frequency-Division Multiplexing Chirp Waveform Processing Method for Joint Radar and Communication Based on Low-Density Parity-Check Coding and Channel Estimation." Electronics 13, no. 2 (January 12, 2024): 334. http://dx.doi.org/10.3390/electronics13020334.

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With the advancement of information technology construction, the integration of radar and communication represents a crucial technological evolution. Driven by the research boom of integrated sensing and communications (ISACs), some scholars have proposed utilizing orthogonal frequency-division multiplexing (OFDM) to separately modulate radar and communication signals. However, the OFDM symbols in this paper incorporate a cyclic prefix (CP) and a virtual carrier (VC) instead of zero padding (ZP). This approach mitigates out-of-band power caused by ZP, in addition to reducing adjacent channel interference (ACI). In addition, we introduce low-density parity-check (LDPC) and use an improved normalized min-sum algorithm (NMSA) in decoding. The enhanced decoding efficiency and minimized system errors render the proposed waveform more suitable for complex environments. In terms of signal processing methods, this paper continues to use radar signals as a priori information to participate in channel estimation. Further, we consider the symbol timing offset (STO) and carrier frequency offset (CFO) issues. In order to obtain more reliable data, we use the minimum mean-square error (MMSE) estimation based on the discrete Fourier transform (DFT) to evaluate the channel. Simulation experiments verify that the system we propose not only realizes the transmission and detection functions but also improves the performance index of the integrated signal, such as the bit error rate (BER) of 7 × 10−5, the peak side lobe ratio (PSLR) of −13.81 dB, and the integrated side lobe ratio (ISLR) of −8.98 dB at a signal-to-noise ratio (SNR) of 10 dB.
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48

Shi, Ruihua, Wei Li, Qinghai Dong, Bingnan Wang, Maosheng Xiang, and Yinshen Wang. "Synthetic Aperture Ladar Motion Compensation Method Based on Symmetric Triangle Linear Frequency Modulation Continuous Wave Segmented Interference." Remote Sensing 16, no. 5 (February 24, 2024): 793. http://dx.doi.org/10.3390/rs16050793.

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Synthetic Aperture Ladar (SAL) is a sensor that combines laser detection technology with synthetic aperture technology to achieve ultra-high-resolution imaging. Due to its extremely short wavelength, SAL is more sensitive to motion errors. The micrometer-level motion will affect the target’s azimuth focus. This article proposes an SAL motion compensation method based on Symmetric Triangular Linear Frequency Modulation Continuous Wave (STLFMCW) segmented interference, utilizing the characteristics of a triangular wave, to solve the problem of target azimuth defocusing. This article first establishes an STLFMCW echo signal model based on the SAL system under the influence of motion errors. Secondly, the radial velocity gradient along the azimuth direction is extracted using the triangular-wave-positive and -negative frequency modulation signals segmented interference method. Then, for the initial phase wrapping problem, the frequency spectral cross-correlation method is used to accurately estimate the initial radial velocity error. The radial velocity gradient is integrated along the azimuth to obtain the platform motion trajectory. Finally, the compensation functions are constructed to complete the echo Range Cell Migration (RCM) correction and residual phase compensation, resulting in a focused SAL image. This article verifies the practical effect of this method in eliminating motion errors using only one-period STLFMCW signal through simulation and real experiments. The quantitative results show that compared with the traditional method, the proposed method reduces the azimuth Peak Sidelobe Ratio (PSLR) by 8dB and the Integrated Sidelobe Ratio (ISLR) by 9 dB. This method has significant improvements and is of great significance for high-resolution FMCW SAL imaging.
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49

Porbaran, Mahyar, and Reza Habibipour. "Relationship between Biofilm Regulating Operons and Various Β-Lactamase Enzymes: Analysis of the Clinical Features of Infections caused by Non-Fermentative Gram-Negative Bacilli (Nfgnb) from Iran." Journal of Pure and Applied Microbiology 14, no. 3 (September 15, 2020): 1723–36. http://dx.doi.org/10.22207/jpam.14.3.11.

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Bacteria are capable of evolving high doses of the drug in various infections by forming biofilms. Perhaps, biofilm regulator genes have different frequencies in β-lactam producing non-fermentative Gram-negative Bacilli (NFGNB). In this study, we investigated the role of biofilm operons of Pseudomonas aeruginosa and Acinetobacter baumannii on the prevalence of different β-lactamase enzymes. One-hundred twenty (120) nosocomial NFGNB isolates were collected from different clinical samples of patients. PCR method was used for the amplification of resistance genes. Isolates were collected, including 50 isolates (41.66%) of P. aeruginosa and 70 isolates (58.33%) of A. baumannii. The distribution of ESBL, AmpC, KPC, and MBL β-lactamase enzymes in P. aeruginosa and A. baumannii isolates were 64%, 58%, 38%,44%, and 57.14%, 60%, 32.85%, 34.28%, respectively. The frequency of csuABC, pgaABC operon in A. baumannii were as follows: pgaA (45.71%), pgaB (32.85%), pgaC (42.85%), csuA (34.28%), csuB (32.85%), csuC (41.42%), and ompA (38.57%). Further, the prevalence of pslABC and pelABC operons in P. aeruginosa isolates were as follows: pslA (58%), pslB (58%), pslD (60%), pelA (64%), pelB (38%), pelC (44%), and algD (68%). This study revealed that the abundance of biofilm regulator genes in NFGNB strains is affected by different β-lactamase enzymes.
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50

Delueg, Stefanie, Christian G. Kirchler, Florian Meischl, Yukihiro Ozaki, Michael A. Popp, Günther K. Bonn, and Christian W. Huck. "At-Line Monitoring of the Extraction Process of Rosmarini Folium via Wet Chemical Assays, UHPLC Analysis, and Newly Developed Near-Infrared Spectroscopic Analysis Methods." Molecules 24, no. 13 (July 6, 2019): 2480. http://dx.doi.org/10.3390/molecules24132480.

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The present study demonstrates the applicability of at-line monitoring of the extraction process of Rosmarinus officinalis L. leaves (Rosmarini folium) and the development of near-infrared (NIR) spectroscopic analysis methods. Therefore, whole dried Rosmarini folium samples were extracted by maceration with 70% (v/v) ethanol. For the experimental design three different specimen-taking plans were chosen. At first, monitoring was carried out using three common analytical methods: (a) total hydroxycinnamic derivatives according to the European Pharmacopoeia, (b) total phenolic content according to Folin–Ciocalteu, and (c) rosmarinic acid content measured by UHPLC-UV analysis. Precision validation of the wet chemical assays revealed a repeatability of (a) 0.12% relative standard deviation (RSD), (b) 1.1% RSD, and (c) 0.28% RSD, as well as an intermediate precision of (a) 4.1% RSD, (b) 1.3% RSD, and (c) 0.55% RSD. The collected extracts were analyzed with a NIR spectrometer using a temperature-controlled liquid attachment. Samples were measured in transmission mode with an optical path length of 1 mm. The combination of the recorded spectra and the previously obtained analytical reference values in conjunction with multivariate data analysis enabled the successful establishment of partial least squares regression (PLSR) models. Coefficients of determination (R2) were: (a) 0.94, (b) 0.96, and (c) 0.93 (obtained by test-set validation). Since Pearson correlation analysis revealed that the reference analyses correlated with each other just one of the PSLR models is required. Therefore, it is suggested that PLSR model (b) be used for monitoring the extraction process of Rosmarini folium. The application of NIR spectroscopy provides a fast and non-invasive alternative analysis method, which can subsequently be implemented for on- or in-line process control.
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