bluuebunny/crossref_metadata_2025_split huggingface dataset:
Virtualized EAST–WEST PON architecture supporting low-latency communication for mobile functional split based on multiaccess edge computing
Authors: Das Sandip , Slyne Frank , Kaszubowska Aleksandra , Ruffini Marco 
Published: June 2020

Ultralow latency end-to-end communication with high reliability is one of the most important requirements in 5G networks to support latency-critical applications. A recent approach toward this target is to deploy edge computing nodes with networking capabilities, known as multiaccess edge computing (MEC), which can greatly reduce the service end-to-end latency. However, the use of MEC nodes poses radical changes to the access network architecture. This requires movement from the classical point-to-multipoint (or point-to-point) structure, used to deliver residential broadband and cloud radio access network (Cloud-RAN) services, to a mesh architecture that can fully embed the MEC nodes with all other end points (i.e., mobile cells, fixed residential, businesses). In this paper, we propose what we believe to be a novel passive optical network (PON)-based mobile fronthaul transport architecture based on PON virtualization that allows EAST–WEST communication along with traditional NORTH–SOUTH communication. The architecture enables the end points of a PON tree, where usually optical networking units (ONUs) are located, to also host MEC nodes by deploying an edge optical line terminal (OLT) capable of communicating directly with adjacent ONUs, by reflecting wavelength signals from the splitter nodes. We experimentally show that signal backscattering due to the reflection at the splitter does not affect the system performance. In addition, using protocol level simulations, we show how this architecture can maintain low latency (

≈

100

µ

s

) in varying mobile traffic conditions by offloading ONUs (i.e., where remote units of Cloud-RAN cells are located) to other edge OLTs through dynamic formation of virtual PON slices. Furthermore, our results show how an efficient migration strategy for ONUs can be chosen depending on the traffic load, different functional split configurations, and the PON capacity.
Tapered Yb-doped fiber enabled monolithic high-power linearly polarized single-frequency laser
Authors: Huang Long , Lai Wenchang , Ma Pengfei , Wang Jin , Su Rongtao , Ma Yanxing , Li Can , Zhi Dong , Zhou Pu 
Published: June 2020

The all-fiber high-power linearly polarized single-frequency fiber laser based on the polarization-maintaining tapered Yb-doped fiber (T-YDF) is systematically studied. As a result, a 300 W-level stable output with linear polarization and nearly diffraction-limited beam quality is demonstrated. In particular, the overall properties of the transverse mode instability (MI) effect in such a single-frequency laser system are discussed in detail for the first time, to the best of our knowledge, including temporal, frequency, polarization, and spatial domains. Furthermore, the beam pointing error taking the MI effect into account is investigated. Theoretical analyses covering both stimulated Brillouin scattering and the MI effects reveal the great potential of the T-YDF for further power scaling as well.
Phase-locked picosecond optical parametric oscillator
Authors: Nandy B. , Chaitanya Kumar S. , Ebrahim-Zadeh M. 
Published: June 2020

We report a degenerate self-phase-locked picosecond optical parametric oscillator (OPO) synchronously pumped by a mode-locked Yb-fiber laser at 1064 nm, delivering broadband output near 2 µm with 2.8 W of average power at

∼

80

M
H
z

repetition rate. By exploiting a 50-mm-long MgO:PPLN crystal providing high gain and low group velocity dispersion under type-0 (

e
→
e
e

) phase matching, the OPO generates a phase-locked degenerate output spectrum with a bandwidth of

∼

202

n
m

centered at 2128 nm in pulses of

∼

21

p
s

duration with excellent passive long-term power and spectral stability in high spatial beam quality. Phase-locked operation results in spectral and power stabilization at exact degeneracy and is further validated by

f
−
2
f

interferometry and radio frequency measurements of OPO output. To the best of our knowledge, this is the first degenerate self-phase-locked OPO in picosecond time scale, and the highest average power reported for a phase-locked ultrafast OPO to date.
2 MW peak power generation in fluorine co-doped Yb fiber prepared by powder-sinter technology
Authors: Leich Martin , Kalide André , Eschrich Tina , Lorenz Martin , Lorenz Adrian , Wondraczek Katrin , Schönfeld Dörte , Langner Andreas , Schötz Gerhard , Jäger Matthias 
Published: June 2020

We report on the first, to the best of our knowledge, implementation of a fluorine co-doped large-mode-area REPUSIL fiber for high peak power amplification in an ultrashort-pulse master oscillator power amplifier. The core material of the investigated step-index fiber with high Yb-doping level, 52 µm core and high core-to-clad ratio of 1:4.2 was fabricated by means of the REPUSIL powder-sinter technology. The core numerical aperture was adjusted by fluorine codoping to 0.088. For achieving high beam quality and for ensuring a monolithic seed path, the LMA fiber is locally tapered. We demonstrate an Yb fiber amplifier with near-diffraction-limited beam quality of

M

2

=

1.3

, which remains constant up to a peak power of 2 MW. This is a record for a tapered single core fiber.
Stable complex conjugate artifact removal in OCT using circularly polarized light as reference
Authors: Liu Xinyu , Ke Mengyuan , Yao Xinwen , Chua Jacqueline , Schmetterer Leopold , Tan Bingyao 
Published: June 2020

In Fourier domain optical coherence tomography (FDOCT), the depth profile is mirrored about the zero delay between the sample and reference optical paths, limiting the imaging depth to half of the entire ranging space and undermining the optimal sensitivity window. We present a new method, to the best of our knowledge, to remove the complex conjugate artifact by using circularly polarized light as reference. Quadrature detection of the complex fringe is achieved by utilizing the intrinsic

λ

/

4

delay between two polarization channels. We use passive broadband polarization optics to control the polarization state of the light in the reference and sample arms and a balanced polarization diversity detection unit to simultaneously detect phase-shifted fringes. We demonstrate a 40 dB artifact suppression ratio with a swept-source optical coherence tomography system. Our proposed method is immune to sample motion and laser phase noise, and imposes no restrictions to the source bandwidth, imaging speed, or computational power. In vivo images of the human finger, as well as the cornea and retina of a non-human primate, were demonstrated.
Spontaneous four-wave mixing in silicon nitride waveguides for broadband coherent anti-Stokes Raman scattering spectroscopy
Authors: Lüpken Niklas M. , Würthwein Thomas , Epping Jörn P. , Boller Klaus-J. , Fallnich Carsten 
Published: June 2020

We present a light source for coherent anti-Stokes Raman scattering (CARS) based on broadband spontaneous four-wave mixing, with the potential to be further integrated. By using 7 mm long silicon nitride waveguides, which offer tight mode confinement and a high nonlinear refractive index coefficient, broadband signal and idler pulses were generated with 4 nJ of input pulse energy. In comparison to fiber-based experiments, the input energy and the waveguide length were reduced by two orders of magnitude, respectively. The idler and residual pump pulses were used for CARS measurements, enabling chemically selective and label-free spectroscopy over the entire fingerprint region, with an ultrafast fiber-based pump source at 1033 nm wavelength. The presented simple light source paves the path towards cost-effective, integrated lab-on-a-chip CARS applications.
Rapid fabrication of high-resolution multi-scale microfluidic devices based on the scanning of patterned femtosecond laser
Authors: Zhang Chenchu , Zhang Jianming , Chen Renfei , Li Jiawen , Wang Chaowei , Cao Rui , Zhang Jingjing , Ye Hanchang , Zhai Hua , Sugioka Koji 
Published: June 2020

Femtosecond-laser-induced two-photon polymerization has distinct
advantages in micro-nanofabrication due to its intrinsic
three-dimensional processing capability and high precision with
sub-100 nanometer fabrication resolution. However, the high resolution
causes a drawback in fabricating large-scale structures due to
unacceptably long processing times. To solve this problem, we applied
the patterned focus as the basic element for scanning processing.
Theoretically, the relationship between patterned-focus scanning
parameters and the uniformity of scanned light field was analyzed and
optimized. Experimentally, we quantitatively investigated the
relationship between the microstructure surface quality and the
parameters of patterned-focus scanning. Based on above, we put forward
a hybrid method that combines the femtosecond laser patterned exposure
with direct-writing fabrication to rapidly fabricate large-scale
microfluidic devices for various practical applications.
Straightforward nano patterning on optical fiber for sensors development
Authors: De Acha Nerea , Elía Víctor , Delgado-Camón Arantzazu , Arregui Francisco J. , Elosúa César 
Published: June 2020

A simple method to prepare a nano pattern along the surface of an optical fiber is applied in this Letter to develop a pH sensor. The template is made of a block copolymer that defines specific locations where gold nano particles are adsorbed on forming clusters. The average diameter of the resulting agglomerates is 121 nm, and the mean distance between the centers is 182 nm. The morphology of the gold cluster array produces localized surface plasmon resonance. The absorbance spectrum is affected by pH variations, and the ratio between the absorption at two different wavelengths is used to characterize the response, which is repetitive and reversible. This Letter highlights the potentiality of this type of chemical nano patterning for the development of optical fiber sensors.
Few-cycle mid-infrared pulses from BaGa2GeSe6
Authors: Elu Ugaitz , Maidment Luke , Vamos Lenard , Steinle Tobias , Haberstroh Florian , Petrov Valentin , Badikov Valeriy , Badikov Dmitrii , Biegert Jens 
Published: June 2020

B
a
G
a

2

G
e
S
e

6

(BGGSe) is a newly developed nonlinear material that is attractive for ultrabroad frequency mixing and ultrashort pulse generation due to its comparably low dispersion and high damage threshold. A numerical study shows the material’s capacity for octave-spanning mid-infrared pulse generation up to 18 µm. In a first experiment, we show that a long crystal length of 2.6 mm yields a pulse energy of 21 pJ at 100 MHz with a spectral bandwidth covering 5.8 to 8.5 µm. The electric field of the carrier-envelope-phase stable pulse is directly measured with electro-optical sampling and reveals a pulse duration of 91 fs, which corresponds to sub-four optical cycles, thus confirming some of the prospects of the material for ultrashort pulse generation and mid-infrared spectroscopy.
40  Gbps heterostructure germanium avalanche photo receiver on a silicon chip
Authors: Benedikovic Daniel , Virot Léopold , Aubin Guy , Hartmann Jean-Michel , Amar Farah , Le Roux Xavier , Alonso-Ramos Carlos , Cassan Eric , Marris-Morini Delphine , Crozat Paul , Boeuf Frédéric , Fédéli Jean-Marc , Kopp Christophe , Szelag Bertrand , Vivien Laurent 
Published: June 2020

Photodetectors are cornerstone components in integrated optical
circuits and are essential for applications underlying modern science
and engineering. Structures harnessing conventional crystalline
materials are typically at the heart of such devices. In particular,
group-IV semiconductors such as silicon and germanium open up more
possibilities for high-performing on-chip photodetection thanks to
their favorable electrical and optical properties at near-infrared
wavelengths and processing compatibility with modern chip
manufacturing. However, scaling the performance of silicon-germanium
photodetectors to technologically relevant levels and benefiting from
improved speed, reduced driving bias, enhanced sensitivity, and
lowered power consumption arguably remains key for densely integrated
photonic links in mainstream shortwave infrared optical
communications. Here we report on a reliable 40 Gbps direct detection
of chip-integrated silicon-germanium avalanche p-i-n photo receiver
driven with low-bias supplies at 1.55 µm wavelength. The avalanche
photodetection scheme calls upon fabrication steps commonly used in
complementary metal-oxide-semiconductor foundries, alleviating the
need for complex epitaxial wafer structures and/or multiple ion
implantation schemes. The photo receiver exhibits an internal
multiplication gain of 120, a high gain-bandwidth product up to
210 GHz, and a low effective ionization coefficient of

∼

0.25

. Robust and stable photodetection at
40 Gbps of on–off keying modulation is achieved at low optical input
powers, without any need for receiver electronic stages.
Simultaneously, compact avalanche p-i-n photodetectors with
submicrometric heterostructures promote error-free operation at
transmission bit rates of 32 Gbps and 40 Gbps, with power
sensitivities of

−

12.8

d
B
m

and

−

11.2

d
B
m

, respectively (for

10

−
9

error rate and without error
correction coding during use). Such a performance in an on-chip
avalanche photodetector is a significant step toward large-scale
integrated optoelectronic systems. These achievements are promising
for use in data center networks, optical interconnects, or quantum
information technologies.
Current Cross Border e-Commerce Companies Developmental Problems AND Countermeasures
Authors: Tseng TzuShan 
Published: June 2020

The development of cross border e-commerce industry is one of important global trends. From eMarketer (2019), the global sales of e-commerce in 2018 was 2.5 trillion US dollars and will reach 7.5 trillion US dollars in 2020. In this number - 7.5 trillion US dollars, the cross border e-commerce consumers will occupy 44.6% of e-commerce’s. Due to the quick development, companies will encounter problems by the way. The research purposes of this study was to discuss problems found through Osterwalder and Pigneur’s business model canvas analysis and provide suggestions. In this sense, During the time of one-year industry-academic cooperation program with Company A, the exploratory case study is relying on several sources of data collections through interviews, case analysis, site-visiting observations and secondary data collection (internal and external data) to analyze Company’s A cross order e-commerce business model and Taiwan’s cross border e-commerce ecosystem. The research subject (Company A) who locate in the vehicles components industry was a Taiwanese SEM and would like to transform into a cross border e-commerce company. The study aimed to explore the cross border e-commerce business model to answer the research question of What is Company A’s recent business model canvas ? If Company A would like to transform into cross border e-commerce, what are the problems? What is Taiwan cross border e-commerce ecosystem which Company A is located ? The research results and suggestions of this cross border e-commerce company are the following. Firstly, the problem is business opportunities are difficult to catch recently and the amount of each order earned is becoming smaller. The suggestion for this problem is to suggest adapting multiple cross border e-commerce portals operations on budgets and “Software Key activities” for decision making. The second problem is the cost of cross border e-commerce logistic is high. The suggest for this problem is to use Big Data Analysis and artificial intelligence (AI) technology to calculate exact oversea inventories. The third problem is lack of trust. The suggest for this problem is localization strategy, to systematically recruit and train the talents who are familiar with the culture, products and markets. And also The study also has some practical implications for cross-border e-commerce companies.
Mediating role of resilience between successful aging and acculturation among older Korean immigrants In the United States
Authors: Lee Jaewon 
Published: June 2020

Background: This study was to investigate how acculturative stress affects older Korean immigrants' successful aging and whether resilience can play a mediator's role to the sample population's successful aging or not. The research design was a cross-sectional survey using three valid and reliable scales such as Successful Aging Scale, Acculturative Stress Scale, and Resilience Scale. A research shows that there is no or minimum correlation between acculturative stress and successful aging (Choi & Thomas, 2009). However, it was hypothesized that although there was a weak correlation between acculturative stress and successful aging, once the resilience involved as a mediator, the correlation would be stronger.
Methods: The study was designed as a self-administered survey research using the scales mentioned above. One hundred and two (N=102) older Koreans who currently enrolled in Adult Health Care Centers in Los Angeles, CA, participated in this study. Multiple Regression, Correlation, ANOVA, and t-test was administered to analyze the collected data.
Results: The results indicated that there was a positive but weak correlation between acculturative stress and the sample population's successful aging rate (r = .252, p<.05). Interestingly, when resilience intervened as a mediator, the correlation between acculturation and successful aging was increased to (r = .622, p<.05). Therefore, the study discovered that the resilience was able to play a mediator's role between acculturative stress and successful aging among the older Korean immigrants.
Implications: The findings can be directed to social work researchers and practitioners to help educate the ethnic older adults in the community on the social and behavioral importance of the positive aspects of aging such as successful aging and healthy aging to increase the chance of community member's longevity. Future research will include other ethnic and immigrant older populations in the community to show internal and external validity of the study related to successful aging, acculturative stress, and resilience.
An Investigation of the Impact of a Flipped Classroom Instructional Approach on High School Students’ Content Knowledge and Attitude Toward the Learning Environment.
Authors: Bell Matthew , Shumway Steven , Wright Geoff 
Published: June 2020

The idea of the “flipped classroom” has become increasingly popular in education. However, very little research in how “flipped classrooms” impact high school students’ ability to perform on exams has been done. The purpose of this research is to add to the body of knowledge and help provide data to investigate how well students learn physics content by using the flipped classroom in a high school Physics with Technology class.
Seven periods of Physics with Technology at Lone Peak High School in Highland, UT were used in this study. Three of the classes were randomly assigned to be “flipped” while the other four were taught using what is considered a “traditional” method of instruction of physics (guided inquiry). The pacing and content was matched each day and all classes participated in the same labs, homework, quizzes and tests. The defining difference is the method which the content was covered. The flipped classes watched video lectures at home to learn the majority of the content, then did what is traditionally known as “homework” in class with the teacher present to help.
In this study, it was found that there was no statistically or practically significant difference in mean test scores for the first three units. Student responses on a survey also showed very little statistical difference in the students’ attitudes towards the classroom environment in either instructional method.
Challenges for Methods of Teaching English Vocabulary to Non-native Students
Authors: Elmahdi Omer Elsheikh Hago , Hezam Abdulrahman Mokbel Mahyoub 
Published: June 2020

This study is meant to have a through argument about the main topic of this research, which is the challenges of teaching methods of English vocabulary to non-native students. The researchers try to introduce a conceptual coverage of certain areas that are relevant to English vocabulary teaching / learning. This conceptual coverage includes: the definition of the term vocabulary, kinds of vocabulary, the importance of vocabulary, general principles for successful vocabulary teaching, teaching vocabulary in the English as a foreign language (EFL) context is challenging, techniques of teaching vocabulary, and the need for teaching vocabulary. Among the qualitative methods the researchers chose the record keeping method. This method makes use of the already existing reliable documents and similar sources of information as the data source. This data can be used in a new research. The researchers have collected a number of relevant studies and quarrying critically and deeply in these studies to signal out the Challenges for Methods of Teaching English Vocabulary to Non-native Students. Qualitative data collection allows collecting data that is non-numeric and helps us to explore how decisions are made and provide a detailed insight. For reaching such conclusions the data that is collected should be holistic, rich and nuanced and findings to emerge through careful analysis. This is why the researchers have examined and collected many relevant references, case studies that deal with teaching vocabulary. To carry out this research the researchers have introduced certain questions and surveyed a huge number of previous studies after covering the relevant literature. Finally, the challenges that are critically obtained by the researchers are classified into three main categories. The first category, challenges related to students, the second one, challenges related to teachers, and the third one, challenges related to methods/ techniques/ strategies of teaching vocabulary.
The temperature model of the thermal re-radiation model in multilayer insulation systems
Authors: Cui Wenhui , Sun Zhenyu , Yang Jian 
Published: June 2020

AbstractIn this manuscript, the temperature model of multilayer insulation (MLI) on a spacecraft solar panel in thermal radiation is considered. The thermal insulation performance of MLI and the stress of the spacecraft are also considered. The thermal equilibrium equation of the surface temperature of MLI spacecraft in the presence of current transfer, and the iterative temperature acquisition algorithm of the front and back surface of solar panel MLI are derived. The Gaussian elimination method is used to invert the high order sparse matrix composed of error coefficients, thus realizing the real-time calculation of thermal re-radiation(TRR). The thermodynamic model was applied to the motion simulation of GPS Block IIR satellites, and the theoretical model was verified based on the actual temperature measurement data of several GPS Block IIR satellites. The simulation results have certain reference value for studying the thermodynamic modeling of MLI spacecraft and TRR perturbation calculation.