462 research outputs found
ON THE FORMATION OF CZTS (CU2ZNSNS4) BASED FILMS FOR PHOTOVOLTAIC APPLICATIONS
Ph.DDOCTOR OF PHILOSOPH
Exploring the Correlation Between Ultrasound Speed and the State of Health of LiFePO Prismatic Cells
Electric vehicles (EVs) have become a popular mode of transportation, with
their performance depending on the ageing of the Li-ion batteries used to power
them. However, it can be challenging and time-consuming to determine the
capacity retention of a battery in service. A rapid and reliable testing method
for state of health (SoH) determination is desired. Ultrasonic testing
techniques are promising due to their efficient, portable, and non-destructive
features. In this study, we demonstrate that ultrasonic speed decreases with
the degradation of the capacity of an LFP prismatic cell. We explain this
correlation through numerical simulation, which describes wave propagation in
porous media. We propose that the reduction of binder stiffness can be a
primary cause of the change in ultrasonic speed during battery ageing. This
work brings new insights into ultrasonic SoH estimation techniques
An Empirical Air-to-Ground Channel Model Based on Passive Measurements in LTE
In this paper, a recently conducted measurement campaign for
unmanned-aerial-vehicle (UAV) channels is introduced. The downlink signals of
an in-service long-time-evolution (LTE) network which is deployed in a suburban
scenario were acquired. Five horizontal and five vertical flight routes were
considered. The channel impulse responses (CIRs) are extracted from the
received data by exploiting the cell specific signals (CRSs). Based on the
CIRs, the parameters of multipath components (MPCs) are estimated by using a
high-resolution algorithm derived according to the space-alternating
generalized expectation-maximization (SAGE) principle. Based on the SAGE
results, channel characteristics including the path loss, shadow fading, fast
fading, delay spread and Doppler frequency spread are thoroughly investigated
for different heights and horizontal distances, which constitute a stochastic
model.Comment: 15 pages, submitted version to IEEE Transactions on Vehicular
Technology. Current status: Early acces
Trajectory-Aided Maximum-Likelihood Algorithm for Channel Parameter Estimation in Ultra-Wideband Large-Scale Arrays
Effect of recombinant human erythropoietin expressions of apoptosis genes in rats following traumatic brain injury
Purpose: To explore the effect of recombinant human erythropoietin (r-HuEPO) on apoptosis in rats after traumatic brain injury.Methods: A total of 48 traumatic brain-injured Sprague Dawley (SD) rats were obtained by improved Feeney’s traumatic brain injury model, and were randomly divided into four groups: normal salinetreated rats (control) and rats treated with r-HuEPO at doses of 1000 U/kg, 3000 U/kg and 5000 U/kg. Brain tissues were collected on the 7th day after trauma surgery. Apoptotic cells, and NF-kappa B (NFĸB)-, c-myc-, and Fas/Fasl-positive cells were identified in brain tissues by immunohistochemical assay.Results: After treatment with r-HuEPO (3000 and 5000 U/kg), expression of NF-κB and Fas/Fasl were significantly decreased (p < 0.05) compared to control rats, especially at the 5000 U/kg dose (p < 0.01). However, for c-myc, no significant difference was observed between r-HuEPO treatment and control groups (p > 0.05). Compared to the 1000 U/kg r-HuEPO group, Fas/Fasl expression levels were significantly lower in the 3000 and 5000 U/kg r-HuEPO groups (p < 0.05). Additionally, expression of NF-κB and Fasl in the 5000 U/kg r-HuEPO group was significantly lower than that in the 3000 U/kg r- HuEPO group (p < 0.05). Moreover, the number of apoptotic cells in the r-HuEPO group (5000 U/kg) was significantly lower than in the control group (p < 0.05).Conclusion: Thus, r-HuEPO may be beneficial for treating traumatic brain injury via inhibition of NFkappa B and Fas/Fasl expressions.Keywords: Recombinant human erythropoietin, NF-kappa B, Traumatic brain injury, Apoptosis, Neuronal damage, Fas/Fasl expressio
Air-to-Ground Channel Characterization for Low-Height UAVs in Realistic Network Deployments
Due to the decrease in cost, size and weight, \acp{UAV} are becoming more and
more popular for general-purpose civil and commercial applications. Provision
of communication services to \acp{UAV} both for user data and control messaging
by using off-the-shelf terrestrial cellular deployments introduces several
technical challenges. In this paper, an approach to the air-to-ground channel
characterization for low-height \acp{UAV} based on an extensive measurement
campaign is proposed, giving special attention to the comparison of the results
when a typical directional antenna for network deployments is used and when a
quasi-omnidirectional one is considered. Channel characteristics like path
loss, shadow fading, root mean square delay and Doppler frequency spreads and
the K-factor are statistically characterized for different suburban scenarios.Comment: 15 pages, accepted in IEEE Transactions on Antennas and Propagatio
More comprehensive facial inversion for more effective expression recognition
Facial expression recognition (FER) plays a significant role in the
ubiquitous application of computer vision. We revisit this problem with a new
perspective on whether it can acquire useful representations that improve FER
performance in the image generation process, and propose a novel generative
method based on the image inversion mechanism for the FER task, termed
Inversion FER (IFER). Particularly, we devise a novel Adversarial Style
Inversion Transformer (ASIT) towards IFER to comprehensively extract features
of generated facial images. In addition, ASIT is equipped with an image
inversion discriminator that measures the cosine similarity of semantic
features between source and generated images, constrained by a distribution
alignment loss. Finally, we introduce a feature modulation module to fuse the
structural code and latent codes from ASIT for the subsequent FER work. We
extensively evaluate ASIT on facial datasets such as FFHQ and CelebA-HQ,
showing that our approach achieves state-of-the-art facial inversion
performance. IFER also achieves competitive results in facial expression
recognition datasets such as RAF-DB, SFEW and AffectNet. The code and models
are available at https://github.com/Talented-Q/IFER-master
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