scholarly journals Output Pulse Characteristics of a Mamyshev Fiber Oscillator

Photonics ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 590
Author(s):  
Haili Han ◽  
Nan-Kuang Chen ◽  
Liqiang Zhang ◽  
Yanru Xie ◽  
Zhen Tian ◽  
...  

The dependence of the output pulse characteristics of a Mamyshev fiber oscillator on cavity parameters is investigated in detail. We analyze the change in pulse spectrum bandwidth, pulse duration, dechirped pulse duration and chirp with the change in fiber group velocity dispersion, fiber nonlinearity, gain, and filters by putting forward a numerical model. In particular, as one of the most important components, the effect of filters bandwidth and the central wavelength interval between them is discussed. The passive fibers are classified into two kinds according to their locations in the cavity, which are the one before the gain fiber and the one after the gain fiber. Numerical simulation results show that a wide spectrum can be obtained by increasing the nonlinearity of the second passive fiber, while the change in nonlinearity of the first passive fiber has a weak effect on spectrum broadening. A wide spectrum could also be obtained by increasing the nonlinearity or the small-signal gain coefficient of the gain fiber. A Yb-doped Mamyshev fiber oscillator is demonstrated. The results show the increase in pump power, which agrees reasonably well with the numerical simulation results.

2012 ◽  
Vol 443-444 ◽  
pp. 424-429
Author(s):  
Ying Zhao ◽  
Qiang Xue ◽  
Lei Liu ◽  
Bing Liang

The simulation model for describing the transportation and transformation of landfill leachate pollutant in landfill, soil and underground water was established. Taking Wuhan Changshankou landfill for example, the numerical simulation was carried out. The simulation results showed that if there’s no any seepage control measure, the groundwater and soil under landfill will be polluted seriously after MSW was filled; the highest pollutant concetration in landfill was about 25000, and the one in groundwater and soil was about 20000; at the thirtieth year, the pollutant concetration in groundwater and soil still remained up to 10000 although the one in landfill was about 0. The simulation results also showed that the vertical stonewall can’t be used as a nature, and artificial seepage control system must be used.


2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
R. Rizwana ◽  
I. Raja Mohamed

We have studied the chaotic and strange nonchaotic phenomena of a simple quasiperiodically forced Wien bridge oscillator circuit with diode as the only nonlinearity in this electronic oscillator system responsible for various nonlinear behaviors. Both the experimental results and the numerical simulation results for their confirmation are provided to show the bifurcation process. Various measures used for the numerical confirmation of SNA are power spectrum, maximal Lyapunov exponent, path of translational variables, mean square displacement, projection of poincaré section, log-log plot, and autocorrelation function. Based upon the numerical results, the birth of SNAs has been identified in the band merging route, intermittency route, and blowout bifurcation route. In addition, the birth of SNAs has been analyzed with peculiar mechanism, namely, “0-1 Test” employing the one state dynamical variable.


Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 328
Author(s):  
Zhiwei Yang ◽  
Xu Wu ◽  
Deqin Ouyang ◽  
Huibin Sun ◽  
Shuangchen Ruan

In this study, we present a swept source that can intelligently control its sweeping speed while satisfying the commercial stability and miniaturization standards. The source’s central wavelength of the output spectrum is 1300 nm and spectral width is greater than 100 nm. Meanwhile, the scan frequency can be adjusted to range from 20 to 100 kHz, and the stability degree of the optical capacity is less than 0.34%. Additionally, this study establishes a numerical model for the swept-source optical coherence tomography (SS–OCT) system and introduces a numerical simulation of the signal produced during the OCT imaging process. The simulation results are helpful to guide the design and construction of the future OCT systems.


2010 ◽  
Vol 148-149 ◽  
pp. 1171-1176
Author(s):  
Ju Hua Huang ◽  
Li Xian Li ◽  
Ying Ying Wan ◽  
Jun Tuan Guo

This paper takes the rear axle cap which is a typical automobile covering part as the research object. 3D and finite element model of it are built, and the drawing process is simulated with Dynaform, then the technological parameters are analyzed and optimized based on the simulation results, finally the part is compared with the one that is processed in practice. The results show that this method is easy and feasible, it not only increase the work efficiency greatly but also improve the quality of products.


2014 ◽  
Vol 905 ◽  
pp. 464-468 ◽  
Author(s):  
Tian Zeng Li ◽  
Yu Wang

The hyperchaotic behaviors in the fractional hyperchaotic Lü system are studied. And we give the lowest orders for generating hyperchaos with different control parameter. Hyperchaos synchronization of Lü system is theoretically and numerically studied using the one-way coupling method. The numerical simulation results demonstrate the effectiveness and validity of the method.


Mathematics ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 183
Author(s):  
Xiaoling Wang ◽  
Xiaofei Guan ◽  
Pei Yin

In this paper, based on the iterative technique, a new explicit Magnus expansion is proposed for the nonlinear stochastic equation d y = A ( t , y ) y d t + B ( t , y ) y ∘ d W . One of the most important features of the explicit Magnus method is that it can preserve the positivity of the solution for the above stochastic differential equation. We study the explicit Magnus method in which the drift term only satisfies the one-sided Lipschitz condition, and discuss the numerical truncated algorithms. Numerical simulation results are also given to support the theoretical predictions.


2014 ◽  
Vol 28 (16) ◽  
pp. 1450129
Author(s):  
Xubo Hu ◽  
Xiangbo Yang ◽  
Songhao Liu

In this paper, by means of three kinds of methods we study the transmission properties of the light through the quasiperiodic multilayers vertically following the generalized third-order Fibonacci (GTOF) sequences. By means of the decomposition–substitution (DS) method we predict that the GTOF systems possess an interesting four-cycle transmissive characteristic at the central wavelength. Based on the electromagnetic wave theory, we then deduce the formulae of propagation matrices and transmission coefficients analytically at the central wavelength and obtain the numerical simulation results at the same time. The results obtained by three kinds of methods accord with each other and three kinds of methods are complementary. The cyclic transmissive characteristics may be useful for the designing of some optical memories, optical logical gates, and other optical controlling devices.


2011 ◽  
Vol 48-49 ◽  
pp. 1310-1314
Author(s):  
Zhi Jian Wang ◽  
Xiao Feng Shang

In order to learn gas flow state in the vacuum high pressure gas quenching furnace, this paper simulates and tests the gas flow under the no-loaded and cold state. Hot wire anemometer is used to measure the speeds of some feature points, on the one hand to provide boundary conditions for the numerical simulation, and on the other hand to compare with the numerical simulation results. FLUENT software is used to simulate the gas flow of nozzle-type vacuum high-pressure gas quenching furnace. The results show that at the center of the furnace appears high-pressure low-speed zone in which is resulted by the gas collision there, and the vortex also appears in the area around the furnace. The results mean that the cooling rate of works will be slow there. Different exit velocities of five nozzles cause the uneven flow distribution, which will affect the cooling uniformity of works. The comparison between the simulation results and the measured results shows that the error is within 10%. It means that numerical simulation method to predict gas flow is feasible and the results are reliable in high pressure gas quenching furnace.


2016 ◽  
Vol 850 ◽  
pp. 610-617 ◽  
Author(s):  
Ji Hui Luo ◽  
Xue Feng Liu ◽  
Lai Xin Shi ◽  
Chang Fei Cheng

Surface segregation exists in two-phase zone continuous casting (TZCC) alloy with wide solid–liquid two phase zone. The surface segregation formation cannot be explained by the traditional solidification theories. ProCAST software was used to simulate the TZCC process for preparing the Cu–4.7 wt%Sn alloy with wide solid–liquid two phase zone. The Sn solute distribution in TZCC Cu–4.7 wt%Sn alloy was investigated, and the surface segregation mechanism of TZCC Cu–4.7 wt%Sn alloy was analyzed. The results showed that numerical simulation results were agreed with that of experimental. TZCC Cu–4.7 wt%Sn alloy in the center firstly started to solidify and resulted in “Λ” shape inclined solid/liquid (S/L) interface near the mold. Therefore, a narrow gap between the wall of the two-phase zone mold and the S/L interface formed. On the one hand, while Cu–4.7 wt%Sn alloy solidified along the opposite continuous casting direction, the solute redistribution between the solid and the liquid occurred, which lead to Sn solute decreased in solid and enriched in front of S/L interface. Because the narrow gap lies in front of inclined S/L interface near the two-phase zone mold, Sn solute enriches in liquid of the narrow gap. On the other hand, during the TZCC process, solid grains nucleate on the wall of the two-phase zone mold, while the melt feeds into the two-phase zone mold which the temperature is in the two-phase zone of the Cu–4.7 wt%Sn alloy. The solute redistribution also occurs while the solid grains grow, thus lead to Sn content increases in front of S/L interface near the wall of the two-phase zone mold. The enriched Sn solute is too late to diffuse, and will quickly flows into the narrow gap, resulting in further increasing of Sn content in the narrow gap. The liquid with enriched Sn solute in the narrow gap will become the surface layer after solidification, which lead to surface segregation layer during the TZCC Cu–4.7 wt%Sn alloy.


Author(s):  
Yuri Morales López ◽  
Marianela Alpízar Vargas ◽  
Ana Lucía Alfaro Arce ◽  
Vicenç Font-Moll

The purpose of this presentation is to show elements associated to the study and analysis of pedagogical practices used by mathematics teachers, taking into consideration different approaches and conceptions derived from theories related to the role of the math teacher. The project highlights the need to use different strategies to analyze the processes occurring in the activities and tasks organized and implemented by the teacher. One of the main tasks in teacher training is to promote the capacity to noticing on the pedagogical activity, where noticing is understood as an inherent process to improve the quality of classroom management. In addition, different analysis models should be compared using examples and experiential practices and the different theories and research projects developed in this field related to this type of analysis. Knowing what happens in the classroom is a task inherent to the math teacher. For sure, if the teacher does not understand or is even able to perceive what is happening in the class, improvement actions are very difficult to implement. Consequently, math teachers must develop the capability of analyzing their pedagogical activity and the related elements. It is not about isolating variables and looking for causal relationships, but rather about understanding the teacher’s activity as the center of the multiple situations occurring in the classroom, which may be known more in depth, if the attention is focused on the organization, ordering, and execution of the tasks planned by the teacher. It must also be understood that the competence of analyzing mentioned here is not an isolated activity without an effect. Such analysis must be approached from an active perspective where scenarios are generated to mitigate complex situations or to value an approach different than the one happening in the classroom. Being aware that there are many aspects to analyze (most likely almost everything that happens is analyzable), we must take a stand on which situations are highly related to what happens in our classroom and which could eventually happen. With such a wide spectrum, some questions that need to be addressed are: What is important in the math education activity and who defines what is important? What elements are of interest to math teachers? How does the analysis conducted relate to the different models of the teacher's knowledge? How does our previous experience influence the assessments we make? How do we distinguish elements of interest to analysis? What is the relationship between reflecting and analyzing? At what stages of the teacher’s activity is an analysis required? What is the ultimate purpose of analyzing teaching activities? What competencies or skills are related to the analysis? What types of analysis are appropriate (content, cognitive, media, among others)? How can we balance the actions derived from the analyses we conduct? From all these questions the most important one that can guide the study of this reflection would be: What should be assessed in pedagogical activities and what is the objective of analyzing such pedagogical activities in math education?


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