scholarly journals Sonar using chaotic sounding signals

2021 ◽  
pp. 36-40
Author(s):  
Ш.С. Фахми ◽  
С.В. Горяинов ◽  
А.В. Калач
Keyword(s):  
Signal To Noise Ratio ◽  
Water Environment ◽  
Deterministic Chaos ◽  
Reference Method ◽  
Current Approach ◽  
Arbitrary System ◽  
Simulated Environment ◽  
Before And After ◽  
Probing Signal ◽  
The Stability

В данной работе рассматривается подход к генерации зондирующего сигнала гидролокатора, основанный на применении систем с детерминированным хаосом. Рассматриваются актуальные подход к генерации зондирующего сигнала при проектировании гидролокаторов. Приводится описание полуявного метода Верле для произвольной системы обыкновенных дифференциальных уравнений. Приводится методология построения композиционных схем для получения методов численного интегрирования произвольного порядка на основе симметричного опорного метода. Приводятся результаты компьютерного моделирования форм различных сигналов до и после прохождения через имитацию водной среды. Приводятся экспериментальные результаты оценки погрешности в распознавании сигнала при различных значениях соотношения сигнал/шум имитируемой среды, проводится сравнительная оценка в значениях, полученных с использованием различных сигналов. Приводятся результаты оценки устойчивости исследуемых сигналов к перекрёстным помехам, проведена сравнительная оценка рассмотренных подходов к генерации зондирующего сигнала. Сделаны выводы о применимости хаотических сигналов в качестве зондирующих In this paper, we consider an approach to generating a sonar sounding signal based on the use of systems with deterministic chaos. The current approach to the generation of sounding singal in the design of sonar is considered. The semi-implicit Wehrle method for an arbitrary system of ordinary differential equations is described. A methodology for constructing composite schemes for obtaining methods of numerical integration of arbitrary order based on the symmetric reference method is presented. The results of computer simulation of the forms of various signals before and after passing through the simulated water environment are presented. Experimental results of estimating the error in signal recognition at different values of the signal-to-noise ratio of the simulated environment are presented, and a comparative assessment is made in the values obtained using different signals. The results of the evaluation of the stability of the studied signals to crosstalk are presented, and a comparative evaluation of the considered approaches to the generation of the probing signal is carried out. Conclusions are drawn about the applicability of chaotic signals as probing signals

scholarly journals New Approaches to Processing Ground-based SAR (GBSAR) Data for Deformation Monitoring

2018 ◽  
Vol 10 (12) ◽  
pp. 1936 ◽  
Author(s):  
Sichun Long ◽  
Aixia Tong ◽  
Ying Yuan ◽  
Zhenhong Li ◽  
Wenhao Wu ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Atmospheric Correction ◽  
Deformation Monitoring ◽  
Atmospheric Effects ◽  
Threshold Optimization ◽  
Before And After ◽  
Multiple Threshold ◽  
The Stability ◽  
Average Coherence

In this paper, aiming at the limitation of persistence scatterers (PS) points selection, a new method for selecting PS points has been introduced based on the average coherence coefficient, amplitude dispersion index, estimated signal-to-noise ratio and displacement standard deviation of multiple threshold optimization. The stability and quality of this method are better than that of a single model. In addition, an atmospheric correction model has also been proposed to estimate the atmospheric effects on Ground-based synthetic aperture radar (GBSAR) observations. After comparing the monitoring results before and after correction, we clearly found that the results are in good agreement with the actual observations after applying the proposed atmospheric correction approach.

The stability of dislocation networks under various oxygen-doping conditions in superconducting Bi2Sr2CaCu2Oy single crystals and their influence on the flux pinning properties

1994 ◽  
Vol 52 ◽  
pp. 802-803
Author(s):  
Y. Feng ◽  
X. Y. Cai ◽  
R. J. Kelley ◽  
D. C. Larbalestier
Keyword(s):  
Single Crystals ◽  
Oxygen Content ◽  
Basal Plane ◽  
Flux Pinning ◽  
Pinning Centers ◽  
Before And After ◽  
Anomalous Peak ◽  
Basal Plane Dislocation ◽  
The Stability ◽  
Further Development

The issue of strong flux pinning is crucial to the further development of high critical current density Bi-Sr-Ca-Cu-O (BSCCO) superconductors in conductor-like applications, yet the pinning mechanisms are still much debated. Anomalous peaks in the M-H (magnetization vs. magnetic field) loops are commonly observed in Bi2Sr2CaCu2Oy (Bi-2212) single crystals. Oxygen vacancies may be effective flux pinning centers in BSCCO, as has been found in YBCO. However, it has also been proposed that basal-plane dislocation networks also act as effective pinning centers. Yang et al. proposed that the characteristic scale of the basal-plane dislocation networksmay strongly depend on oxygen content and the anomalous peak in the M-H loop at ˜20-30K may be due tothe flux pinning of decoupled two-dimensional pancake vortices by the dislocation networks. In light of this, we have performed an insitu observation on the dislocation networks precisely at the same region before and after annealing in air, vacuumand oxygen, in order to verify whether the dislocation networks change with varying oxygen content Inall cases, we have not found any noticeable changes in dislocation structure, regardless of the drastic changes in Tc and the anomalous magnetization. Therefore, it does not appear that the anomalous peak in the M-H loops is controlled by the basal-plane dislocation networks.

Sorbitol enhances the physicochemical stability of B12 vitamers

2020 ◽  
Vol 90 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Andrew Hadinata Lie ◽  
Maria V Chandra-Hioe ◽  
Jayashree Arcot
Keyword(s):  
Ascorbic Acid ◽  
Uv Light ◽  
Heat Exposure ◽  
Water Soluble ◽  
Uv Exposure ◽  
Physicochemical Stability ◽  
Before And After ◽  
The Stability

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

scholarly journals The model and simulation of low impact development of the sponge airport, China

2019 ◽  
Vol 20 (2) ◽  
pp. 383-394 ◽  
Author(s):  
Jing Peng ◽  
Jiayi Ouyang ◽  
Lei Yu ◽  
Xinchen Wu
Keyword(s):  
Flood Control ◽  
Low Impact Development ◽  
Water Environment ◽  
Drainage System ◽  
Practical Significance ◽  
International Airport ◽  
Model And Simulation ◽  
Impervious Area ◽  
Before And After ◽  
Airport Runway

Abstract Recently urban waterlogging problems have become more and more serious, and the construction of an airport runway makes the impervious area of the airport high, which leads to the deterioration of the water environment and frequent waterlogging disasters. It is of great significance to design and construct the sponge airport with low impact development (LID) facilities. In this paper, we take catchment N1 of Beijing Daxing International Airport as a case study. The LID facilities are designed and the runoff process of a heavy rainfall in catchment N1 is simulated before and after the implementation of LID facilities. The results show that the total amount of surface runoff, the number of overflow junctions and full-flow conduits of the rainwater drainage system in catchment N1 of Beijing Daxing International Airport are significantly reduced after the implementation of the LID facilities. Therefore, the application of LID facilities has greatly improved the ability of the airport to remove rainwater and effectively alleviated the risk of waterlogging in the airport flight area. This study provides theoretical support for airport designers and managers to solve flood control and rainwater drainage problems and has vital practical significance.

scholarly journals Investigation of Hydrothermally Stressed Silicone Rubber/Silica Micro and Nanocomposite for the Coating High Voltage Insulation Applications

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3567
Author(s):  
Faiza Faiza ◽  
Abraiz Khattak ◽  
Safi Ullah Butt ◽  
Kashif Imran ◽  
Abasin Ulasyar ◽  
...  
Keyword(s):  
Silicone Rubber ◽  
Structural Changes ◽  
Polymer Chains ◽  
Hydrothermal Conditions ◽  
Silica Filler ◽  
Before And After ◽  
Aging Conditions ◽  
The Stability ◽  
Micro Silica ◽  
Applied Stresses

Silicone rubber is a promising insulating material that has been performing well for different insulating and dielectric applications. However, in outdoor applications, environmental stresses cause structural and surface degradations that diminish its insulating properties. This effect of degradation can be reduced with the addition of a suitable filler to the polymer chains. For the investigation of structural changes and hydrophobicity four different systems were fabricated, including neat silicone rubber, a micro composite (with 15% micro-silica filler), and nanocomposites (with 2.5% and 5% nanosilica filler) by subjecting them to various hydrothermal conditions. In general, remarkable results were obtained by the addition of fillers. However, nanocomposites showed the best resistance against the applied stresses. In comparison to neat silicone rubber, the stability of the structure and hydrophobic behavior was better for micro-silica, which was further enhanced in the case of nanocomposites. The inclusion of 5% nanosilica showed the best results before and after applying aging conditions.

scholarly journals Performance of a capnodynamic method estimating cardiac output during respiratory failure - before and after lung recruitment

2019 ◽  
Vol 34 (6) ◽  
pp. 1199-1207
Author(s):  
Thorir Svavar Sigmundsson ◽  
Tomas Öhman ◽  
Magnus Hallbäck ◽  
Eider Redondo ◽  
Fernando Suarez Sipmann ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Respiratory Failure ◽  
Reference Method ◽  
Hemodynamic Instability ◽  
Lung Lavage ◽  
Lung Recruitment ◽  
Recruitment Manoeuvre ◽  
Percentage Error ◽  
Before And After ◽  
The Right

AbstractRespiratory failure may cause hemodynamic instability with strain on the right ventricle. The capnodynamic method continuously calculates cardiac output (CO) based on effective pulmonary blood flow (COEPBF) and could provide CO monitoring complementary to mechanical ventilation during surgery and intensive care. The aim of the current study was to evaluate the ability of a revised capnodynamic method, based on short expiratory holds (COEPBFexp), to estimate CO during acute respiratory failure (LI) with high shunt fractions before and after compliance-based lung recruitment. Ten pigs were submitted to lung lavage and subsequent ventilator-induced lung injury. COEPBFexp, without any shunt correction, was compared to a reference method for CO, an ultrasonic flow probe placed around the pulmonary artery trunk (COTS) at (1) baseline in healthy lungs with PEEP 5 cmH2O (HLP5), (2) LI with PEEP 5 cmH2O (LIP5) and (3) LI after lung recruitment and PEEP adjustment (LIPadj). CO changes were enforced during LIP5 and LIPadj to estimate trending. LI resulted in changes in shunt fraction from 0.1 (0.03) to 0.36 (0.1) and restored to 0.09 (0.04) after recruitment manoeuvre. Bias (levels of agreement) and percentage error between COEPBFexp and COTS changed from 0.5 (− 0.5 to 1.5) L/min and 30% at HLP5 to − 0.6 (− 2.3 to 1.1) L/min and 39% during LIP5 and finally 1.1 (− 0.3 to 2.5) L/min and 38% at LIPadj. Concordance during CO changes improved from 87 to 100% after lung recruitment and PEEP adjustment. COEPBFexp could possibly be used for continuous CO monitoring and trending in hemodynamically unstable patients with increased shunt and after recruitment manoeuvre.

Regulation of Laijiapu Waterway in Jingjiang Reach

2014 ◽  
Vol 501-504 ◽  
pp. 2001-2006
Author(s):  
Ya Liu ◽  
Li Zheng ◽  
Cheng Tao Huang ◽  
Zhao Biao Huang ◽  
Lin Liu
Keyword(s):  
Yangtze River ◽  
Three Gorges Reservoir ◽  
Three Gorges ◽  
The Yangtze River ◽  
Point Bar ◽  
The Three Gorges Reservoir ◽  
The Three Gorges ◽  
Before And After ◽  
The Stability ◽  
Channel Bar

After impoundment of the Three Gorges Reservoir, Jingjiang reach, in the middle of the Yangtze River, has gradually shown a series of atypical fluvial features, adversely affecting the maintenance of waterways. Citing the Laijiapu Waterway, a meandering segment in the lower Jingjiang for example, this paper compared the fluvial features of the channel before and after the impoundment, summed up its navigation-obstructing features, and proposed guarding the point bar on the convex bank and channel bar in the widening section as a key to maintaining the stability of the navigation channels.

scholarly journals Efficacy of Selective Grinding Guided by an Occlusal Splint in Management of Myofascial Pain: A Prospective Clinical Trial

2017 ◽  
Vol 11 (1) ◽  
pp. 301-311
Author(s):  
Felipe J. Fernández-González ◽  
Jorge Cabero-López ◽  
Aritza Brizuela ◽  
Ivan Suazo ◽  
Esteban Pérez-Pevida ◽  
...  
Keyword(s):  
Temporomandibular Joint ◽  
Myofascial Pain ◽  
Vertical Displacement ◽  
Occlusal Splint ◽  
Significant Difference ◽  
Before And After ◽  
Skeletal Pattern ◽  
Condylar Position ◽  
The Stability ◽  
Facial Types

Background:For patients whose centric relation (CR) has not been considered at the start and during treatment, the task of achieving an occlusal scheme that works together with the temporomandibular joint, the muscles, and the structures of the stomatognathic apparatus becomes a major concern.Objective:This study aims to describe a reproducible, predictable and to date unreported procedure of selective grinding guided by an occlusal splint and to analyze condylar position (CP) based on the skeletal pattern.Methods:A total of 72 symptomatic patients (38 females and 34 males) were classified into three groups: hyperdivergent, intermediate and hypodivergent. CP was quantified by mounted casts on a measures condyle displacement (MCD) device. Helkimo index was also performed in order to assess the severity of the temporomandibular joint (TMJ) disorders attending to clinical dysfunction, occlusal state and anamnestic dysfunction. Once the stability had been obtained, the splint was progressively reduced until the maximum intercuspation (MIC) was achieved.Results:The vertical displacement was found to be significantly different between the hyperdivergent and other two groups (p<0.01). Comparisons of MCD analysis before and after the selective grinding procedure identified a statistically significant difference in the horizontal and vertical CP (p<0.01) between the different groups whereas the Helkimo Index showed a clear improvement of TMJ disorders.Conclusion:All facial types, specially the hyperdivergent face type, showed a reduction in condylar displacement (CD) and less craniomandibular symptoms using this procedure, making it an excellent technique for clinicians.

scholarly journals Survival and echocardiographic evaluation of dogs with idiopathic dilated cardiomyopathy treated with carvedilol

2010 ◽  
Vol 62 (3) ◽  
pp. 555-563 ◽  
Author(s):  
E.C. Soares ◽  
G.G. Pereira ◽  
L.C. Petrus ◽  
M. Leomil Neto ◽  
F.L. Yamaki ◽  
...  
Keyword(s):  
Dilated Cardiomyopathy ◽  
Ventricular Remodeling ◽  
Left Ventricular ◽  
Idiopathic Dilated Cardiomyopathy ◽  
P Value ◽  
Echocardiographic Evaluation ◽  
Before And After ◽  
Group A ◽  
The Stability ◽  
Group B

Sixty dogs with idiopathic dilated cardiomyopathy were randomly treated with traditional therapy - digitalis, diuretics, angiotensin-converting inhibitors - (group A) or treated with these drugs plus carvedilol (group B). Echocardiographic variables were measured before and after 3, 13, 26, and 52 weeks of treatment or until death. Comparisons between groups and time were performed. No significant differences between groups were found in the most of the echocardiographic variables. The left ventricular end-systolic diameter indexed to body surface area (LVESDi) increased significantly in the group A dogs compared to the group B animals. The survival of groups A and B dogs were not different (P-value=0.1137). In conclusion, the stability of the LVESDi observed in the group treated with carvedilol may represent the beneficial effect over the ventricular remodeling.

scholarly journals The Efficiency of a Group Counseling Program Based on Psychodrama in Enhancing Self-awareness and Reducing Tension among tenth Grade Students In Qalqilia City

2019 ◽  
Vol 3 (18) ◽  
Author(s):  
Said Yousef Swilem
Keyword(s):  
Group Counseling ◽  
Control Group ◽  
Self Awareness ◽  
Counseling Program ◽  
Before And After ◽  
Tenth Grade ◽  
Post Test ◽  
Group Members ◽  
The Stability ◽  
And Control

The purpose of this study is to examine the efficiency of a group counseling program based on psychodrama in improving self-awareness and reducing tension among tenth grade students in Qalqilia City and examining the nature and the direction of the relationship between self-consciousness and tension, the sample of study consisted of (20) students whom were distributed randomly equally to two groups the first is an experimental contains (10) students and the second is a control group contains (10) students in light of a tension variable, they are drawn out from (152) students in governmental schools who obtained the highest stress scale for the current study, a counseling program has been built based on the principles and methodology methods of psychodrama which contained (13) sessions, the current study used a measure of self-awareness and tension before and after the program. The researcher used the semi-experimental design to verify the validity of the two instruments they were presented to a group of specialized consultants. The stability coefficient was then calculated using Cronbach Alpha, where the stability value of the self-awareness scale was 0.81 and tension scale was 0.90. The mean and standard deviations were calculated and the Shapiro-Wilk test was used to examine the normal distribution probability of the variables of self-awareness and tension. The results revealed in the non-moderate distribution of individual responses to the two variables. The Mann-Whitney test, the Wilcoxon Signed Ranks Test, and the Spearman Product-Moment Correlation Coefficient test were used. The results showed differences between the experimental and control groups in the post-test of self-awareness and stress measures and for group members this is an indication of the effectiveness of the psychodrama -based counseling program in improving self-awareness and reducing stress among tenth grade students in Qalqilia city and the absence of differences in experimental group members between the tribal and remote testing methods of self-awareness and differences in group members for testing between the two pre-test and post- test of stress. The researcher recommends that self-awareness and stress in the adolescent group should be addressed through the psychodrama -based counseling programs.    

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