289 research outputs found
Growth of Large Domain Epitaxial Graphene on the C-Face of SiC
Growth of epitaxial graphene on the C-face of SiC has been investigated.
Using a confinement controlled sublimation (CCS) method, we have achieved well
controlled growth and been able to observe propagation of uniform monolayer
graphene. Surface patterns uncover two important aspects of the growth, i.e.
carbon diffusion and stoichiometric requirement. Moreover, a new "stepdown"
growth mode has been discovered. Via this mode, monolayer graphene domains can
have an area of hundreds of square micrometers, while, most importantly, step
bunching is avoided and the initial uniformly stepped SiC surface is preserved.
The stepdown growth provides a possible route towards uniform epitaxial
graphene in wafer size without compromising the initial flat surface morphology
of SiC.Comment: 18 pages, 8 figure
TcGAN: Semantic-Aware and Structure-Preserved GANs with Individual Vision Transformer for Fast Arbitrary One-Shot Image Generation
One-shot image generation (OSG) with generative adversarial networks that
learn from the internal patches of a given image has attracted world wide
attention. In recent studies, scholars have primarily focused on extracting
features of images from probabilistically distributed inputs with pure
convolutional neural networks (CNNs). However, it is quite difficult for CNNs
with limited receptive domain to extract and maintain the global structural
information. Therefore, in this paper, we propose a novel structure-preserved
method TcGAN with individual vision transformer to overcome the shortcomings of
the existing one-shot image generation methods. Specifically, TcGAN preserves
global structure of an image during training to be compatible with local
details while maintaining the integrity of semantic-aware information by
exploiting the powerful long-range dependencies modeling capability of the
transformer. We also propose a new scaling formula having scale-invariance
during the calculation period, which effectively improves the generated image
quality of the OSG model on image super-resolution tasks. We present the design
of the TcGAN converter framework, comprehensive experimental as well as
ablation studies demonstrating the ability of TcGAN to achieve arbitrary image
generation with the fastest running time. Lastly, TcGAN achieves the most
excellent performance in terms of applying it to other image processing tasks,
e.g., super-resolution as well as image harmonization, the results further
prove its superiority
Fuzzy Knowledge Distillation from High-Order TSK to Low-Order TSK
High-order Takagi-Sugeno-Kang (TSK) fuzzy classifiers possess powerful
classification performance yet have fewer fuzzy rules, but always be impaired
by its exponential growth training time and poorer interpretability owing to
High-order polynomial used in consequent part of fuzzy rule, while Low-order
TSK fuzzy classifiers run quickly with high interpretability, however they
usually require more fuzzy rules and perform relatively not very well. Address
this issue, a novel TSK fuzzy classifier embeded with knowledge distillation in
deep learning called HTSK-LLM-DKD is proposed in this study. HTSK-LLM-DKD
achieves the following distinctive characteristics: 1) It takes High-order TSK
classifier as teacher model and Low-order TSK fuzzy classifier as student
model, and leverages the proposed LLM-DKD (Least Learning Machine based
Decoupling Knowledge Distillation) to distill the fuzzy dark knowledge from
High-order TSK fuzzy classifier to Low-order TSK fuzzy classifier, which
resulting in Low-order TSK fuzzy classifier endowed with enhanced performance
surpassing or at least comparable to High-order TSK classifier, as well as high
interpretability; specifically 2) The Negative Euclidean distance between the
output of teacher model and each class is employed to obtain the teacher
logits, and then it compute teacher/student soft labels by the softmax function
with distillating temperature parameter; 3) By reformulating the
Kullback-Leibler divergence, it decouples fuzzy dark knowledge into target
class knowledge and non-target class knowledge, and transfers them to student
model. The advantages of HTSK-LLM-DKD are verified on the benchmarking UCI
datasets and a real dataset Cleveland heart disease, in terms of classification
performance and model interpretability
Exploring Impaired SERCA Pump-Caused Alternation Occurrence in Ischemia
Impaired sarcoplasmic reticulum (SR) calcium transport ATPase (SERCA) gives rise to Ca(2+) alternans and changes of the Ca2+release amount. These changes in Ca(2+) release amount can reveal the mechanism underlying how the interaction between Ca(2+) release and Ca(2+) uptake induces Ca(2+) alternans. This study of alternans by calculating the values of Ca(2+) release properties with impaired SERCA has not been explored before. Here, we induced Ca(2+) alternans by using an impaired SERCA pump under ischemic conditions. The results showed that the recruitment and refractoriness of the Ca(2+) release increased as Ca(2+) alternans occurred. This indicates triggering Ca waves. As the propagation of Ca waves is linked to the occurrence of Ca(2+) alternans, the "threshold" for Ca waves reflects the key factor in Ca(2+) alternans development, and it is still controversial nowadays. We proposed the ratio between the diastolic network SR (NSR) Ca content (Cansr) and the cytoplasmic Ca content (Ca i ) (Cansr/Ca i ) as the "threshold" of Ca waves and Ca(2+) alternans. Diastolic Cansr, Ca i , and their ratio were recorded at the onset of Ca(2+) alternans. Compared with certain Cansr and Ca i , the "threshold" of the ratio can better explain the comprehensive effects of the Ca(2+) release and the Ca(2+) uptake on Ca(2+) alternans onset. In addition, these ratios are related with the function of SERCA pumps, which vary with different ischemic conditions. Thus, values of these ratios could be used to differentiate Ca(2+) alternans from different ischemic cases. This agrees with some experimental results. Therefore, the certain value of diastolic Cansr/Ca i can be the better "threshold" for Ca waves and Ca(2+) alternans
Formulation of structured bounding surface model with a destructuration law for natural soft clay
A destructuration law considering both isotropic destructuration and frictional destructuration was suggested to simulate the loss of structure of natural soft clay during plastic straining. The term isotropic destructuration was used to address the reduction of the bounding surface, and frictional destructuration addresses the decrease of the critical state stress ratio as a reflection of reduction of internal friction angle. A structured bounding surface model was formulated by incorporating the proposed destructuration law into the framework of bounding surface constitutive model theory. The proposed model was validated on Osaka clay through undrained triaxial compression test and one-dimensional compression test. The influences of model parameters and bounding surface on the performance of the proposed model were also investigated. It is proved by the good agreement between predictions and experiments that the proposed model can well capture the structured behaviors of natural soft clay
A Wide-Bandwidth Monopolar Patch Antenna with Dual-Ring Couplers
A new center-fed circular patch antenna with two coupled annular rings is presented. When the two annular rings are coupled properly, a wide band from 5.45 GHz to 7.16 GHz is achieved with a monopole-like radiation pattern. Measured results show that the antenna with a low profile of 0.027 wavelengths (at 5.45 GHz) has a bandwidth of 27.1% and a measured maximum gain of 6 dBi. The radiation pattern is omnidirectional and remains relatively stable within the operating band
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Experimental investigation on the effects of bed slope and tailwater on dam-break flows
YesUnderstanding of the characteristics of dam-break flows moving along a sloping wet bed can help to timely issue flood warning and risk mitigation. In this study, laboratory experiments are carried out in a large flume for a wide range of upstream water depth, bed slopes and tailwater depth. The water level is recorded and processed to calculate the mean velocity and wave celerity. Results show that the increase of the bed slope will significantly accelerate the wave-front celerity for the downstream dry bed, while the negative wave celerity will decrease. When water depth ratio α ≥ 0.3 (defined as the ratio of initial downstream water depth over the upstream water depth of dam), there are extra negative waves propagating towards the reservoir area after the flow has developed for a period of time. When α ≥ 0.6, there are the Favre waves propagating downstream. The water level and the mean velocity fluctuate due to the influence of the extra negative waves and the Favre waves. Such fluctuant frequency increases with the increase of the water depth ratio. The empirical formulas are obtained for the celerity of the first extra negative wave and the first downstream wave. The variation of wave-front height is very similar under three bed slopes investigated in this study, while the maximum wave-front height occurs when α = 0.2. The present study broadens the understanding of the effects of the bed slope and the tailwater level on the movement of the dam-break flows. Furthermore, experimental results are also compared with some analytical solutions. The validity of the assumptions made during the development of these analytical solutions and their limitations are discussed by comparing with the experimental measurements.The National Natural Science Foundation of China (Grant No: 51879179), the Open Fund from the State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University (SKHL1809) and Sichuan Science and Technology Program (No. 2019JDTD0007)
Experiments on bright field and dark field high energy electron imaging with thick target material
Using a high energy electron beam for the imaging of high density matter with
both high spatial-temporal and areal density resolution under extreme states of
temperature and pressure is one of the critical challenges in high energy
density physics . When a charged particle beam passes through an opaque target,
the beam will be scattered with a distribution that depends on the thickness of
the material. By collecting the scattered beam either near or off axis,
so-called bright field or dark field images can be obtained. Here we report on
an electron radiography experiment using 45 MeV electrons from an S-band
photo-injector, where scattered electrons, after interacting with a sample, are
collected and imaged by a quadrupole imaging system. We achieved a few
micrometers (about 4 micrometers) spatial resolution and about 10 micrometers
thickness resolution for a silicon target of 300-600 micron thickness. With
addition of dark field images that are captured by selecting electrons with
large scattering angle, we show that more useful information in determining
external details such as outlines, boundaries and defects can be obtained.Comment: 7pages, 7 figure
Diagnosis and management of a scrotal wall mass with the aid of a scrotoscope: a descriptive observational study
Background and objective: A scrotal wall mass is relatively rare in
clinical practice, and very difficult to differentiate from a scrotal content
lesion by a physical or ultrasound examination. In this study, we
share our experience with the scrotoscope for diagnosing and
treating scrotal wall masses.
Methods: We retrospectively reviewed all clinical data of
scrotal wall mass patients treated by our medical team between
June 2015 and July 2019. Diagnostic value was evaluated by
comparison with a Doppler ultrasound examination and therapeutic value was
evaluated by comparison with traditional surgery. Suspected scrotal tuberculosis
or malignant scrotal tumor patients were excluded.
Results: Six patients with scrotal wall masses were diagnosed and
treated with the scrotoscope. A preoperative ultrasound
examination led to an ambiguous or incorrect diagnosis for the
origin of the scrotal wall masses in all six cases. The location of all of the
masses was confirmed by exploring with the scrotoscope. Three patients were
diagnosed with scrotal wall cysts, and one was successfully resected during the
procedure; the other two were resected through a small incision. Four scrotal
wall solid masses were resected in the other three patients
through small incisions after the diagnosis using the scrotoscope. No wound
infection, scrotal edema, hematoma, chronic scrotal pain, or injury to the
testicles or epididymis were observed.
Conclusions: Scrotal wall masses are relatively rare, and it was very
difficult to obtain a firm diagnosis of their origin using preoperative
ultrasound. The scrotoscope confirmed localization of the tumor, and provided us
important information for a minimally invasive resection. Endoscopic resection of
a mass can be performed using a scrotoscope
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