55 research outputs found
Behaviour Analysis of Left-Turning Mopeds at Signal Controlled Intersections – A Case Study in Yancheng City
Mopeds (electric bicycles and light motorcycles) are commonly used as a personal transportation mode in China. However, the understanding of characteristics of left-turning mopeds at signal-controlled intersections has been relatively limited. To bridge this gap, firstly, this paper proposed a video conversion method of moped movement data acquisition. Then, a method of data accuracy verification was introduced by comparing the results between the field experiment and the video conversion method. Secondly, the ideal traffic space for left-turn mopeds from different entrances was defined to analyse the characteristics of the left-turning mopeds at intersections. Further, three indicators, namely, transverse distance, the proportion of left-turning mopeds with crossing behaviour, and the average number of avoidance behaviour, were proposed and used to analyse the asymmetrical characteristics behaviour, crossing behaviour, and avoidance behaviour. Finally, based on empirical data collected from five signal-controlled intersections, the proposed methods and behaviours were analysed. This paper provides both a valid method of obtaining the position data of mopeds and a reliable basis for improving the safety of left-turning moped riders at urban signal-controlled intersections
Metasurface-Based Free-Space Multi-port Beam Splitter with Arbitrary Power Ratio
A beam splitter (BS) is one of the most critical building blocks in optical
systems. Despite various attempts of flat-type BSs to miniaturize the
conventional cube BS reported, it remains a challenge to realize an ultrathin
optical BS with multi-port output, non-uniform splitting ratio and steerable
outgoing directions. Herein, we have demonstrated a free-space optical
multi-port beam splitter (MPBS) based on a polarization-independent
all-dielectric metasurface. By applying an optimized phase-pattern paradigm via
a gradient-descent-based iterative algorithm to amorphous silicon (a-Si)
metasurfaces, we have prepared a variety of MPBS samples with arbitrarily
predetermined output port number (2~7), power ratio and spatial distribution of
output beams. The experimental results reveal that the fabricated MPBSs could
achieve high total splitting efficiency (TSE, above 74.7%) and beam-splitting
fidelity (similarity, above 78.4%) within the bandwidth of 100 nm (1500~1600
nm). We envision that such MPBS could provide fabulous flexibility for optical
integrated system and diverse applications
An On-demand Photonic Ising Machine with Simplified Hamiltonian Calculation by Phase-encoding and Intensity Detection
Photonic Ising machine is a new paradigm of optical computing, which is based
on the characteristics of light wave propagation, parallel processing and low
loss transmission. Thus, the process of solving the combinatorial optimization
problems can be accelerated through photonic/optoelectronic devices. In this
work, we have proposed and demonstrated the so-called Phase-Encoding and
Intensity Detection Ising Annealer (PEIDIA) to solve arbitrary Ising problems
on demand. The PEIDIA is based on the simulated annealing algorithm and
requires only one step of optical linear transformation with simplified
Hamiltonian calculation. With PEIDIA, the Ising spins are encoded on the phase
term of the optical field and only intensity detection is required during the
solving process. As a proof of principle, several 20 and 30-dimensional Ising
problems have been solved with high ground state probability
Origami-inspired soft twisting actuator
Soft actuators have shown great advantages in compliance and morphology
matched for manipulation of delicate objects and inspection in a confined
space. There is an unmet need for a soft actuator that can provide torsional
motion to e.g. enlarge working space and increase degrees of freedom. Towards
this goal, we present origami-inspired soft pneumatic actuators (OSPAs) made
from silicone. The prototype can output a rotation of more than one revolution
(up to 435{\deg}), more significant than its counterparts. Its rotation ratio
(=rotation angle/ aspect ratio) is more than 136{\deg}, about twice the largest
one in other literature. We describe the design and fabrication method, build
the analytical model and simulation model, and analyze and optimize the
parameters. Finally, we demonstrate the potentially extensive utility of the
OSPAs through their integration into a gripper capable of simultaneously
grasping and lifting fragile or flat objects, a versatile robot arm capable of
picking and placing items at the right angle with the twisting actuators, and a
soft snake robot capable of changing attitude and directions by torsion of the
twisting actuators.Comment: 9 figures. Soft Robotics (2022
Syntrophic Growth of Geobacter sulfurreducens Accelerates Anaerobic Denitrification
Nitrate is considered as a contamination since it’s over discharging to water incurs environmental problems. However, nitrate is an ideal electron sink for anaerobic pollutant degraders desiring electron acceptors due to the high redox potential. Unfortunately, not all degraders can directly reduce nitrate, and the anaerobic direct interspecies electron transfer (DIET) between degraders and denitrifiers has not been confirmed yet. Here we demonstrated that syntrophic growth of Geobacter sulfurreducens PCA with denitrifying microbial community at anaerobic condition eliminated the lag phase of 15 h and improved the denitrification rate by 13∼51% over a broad C/N ratio of 0.5 to 9. Quantitative PCR revealed that G. sulfurreducens selectively enhanced the expression of nirS coding for a cytochrome cd1-nitrite reductase, resulting in a fast and more complete denitrification. Geobacter also selectively enriched its potential denitrifying partners – Diaphorobacter, Delftia, and Shinella – to form spherical aggregates. More studies of the binary culture system need to be carried out to confirm the syntrophic mechanism of Geobacter and denitrifiers in the future. These findings extend our knowledge on understanding the anaerobic bacterial interspecies electron transfer in the denitrification process, which has broader implications in fast selection and stabilization of denitrifiers in wastewater treatment plant, and general understanding of ecology for nitrogen and metal cycling
Constraining Ultralight Dark Matter through an Accelerated Resonant Search
Experiments aimed at detecting ultralight dark matter typically rely on
resonant effects, which are sensitive to the dark matter mass that matches the
resonance frequency. In this study, we investigate the nucleon couplings of
ultralight axion dark matter using a magnetometer operating in a nuclear
magnetic resonance (NMR) mode. Our approach involves the use of a Ne
spin-based sensor, which features the lowest nuclear magnetic moment among
noble-gas spins. This configuration allows us to achieve an ultrahigh
sensitivity of 0.73 fT/Hz at around 5 Hz, corresponding to energy
resolution of approximately 1.5. Our analysis reveals that under certain
conditions it is beneficial to scan the frequency with steps significantly
larger than the resonance width. The analytical results are in agreement with
experimental data and the scan strategy is potentially applicable to other
resonant searches. Further, our study establishes stringent constraints on
axion-like particles (ALP) in the 4.5--15.5 Hz Compton-frequency range coupling
to neutrons and protons, improving on prior work by several-fold. Within a band
around 4.6--6.6 Hz and around 7.5 Hz, our laboratory findings surpass
astrophysical limits derived from neutron-star cooling. Hence, we demonstrate
an accelerated resonance search for ultralight dark matter, achieving an
approximately 30-fold increase in scanning step while maintaining competitive
sensitivity.Comment: 13 pages, 9 figure
Cancer-associated fibroblast related gene signature in Helicobacter pylori-based subtypes of gastric carcinoma for prognosis and tumor microenvironment estimation in silico analysis
IntroductionGastric cancer (GC) remains the major constituent of cancer-related deaths and a global public health challenge with a high incidence rate. Helicobacter pylori (HP) plays an essential role in promoting the occurrence and progression of GC. Cancer-associated fibroblasts (CAFs) are regarded as a significant component in the tumor microenvironment (TME), which is related to the metastasis of GC. However, the regulation mechanisms of CAFs in HP-related GC are not elucidated thoroughly.MethodsHP-related genes (HRGs) were downloaded from the GSE84437 and TCGA-GC databases. The two databases were combined into one cohort for training. Furthermore, the consensus unsupervised clustering analysis was obtained to sort the training cohort into different groups for the identification of differential expression genes (DEGs). Weighted correlation network analysis (WGCNA) was performed to verify the correlation between the DEGs and cancer-associated fibroblasts which were key components in the tumor microenvironment. The least absolute shrinkage and selection operator (LASSO) was executed to find cancer-associated fibroblast-related differential expression genes (CDEGs) for the further establishment of a prognostic model.Results and discussionIn this study, 52 HP-related genes (HRGs) were screened out based on the GSE84437 and TCGA-GC databases. A total of 804 GC samples were analyzed, respectively, and clustered into two HP-related subtypes. The DEGs identified from the two subtypes were proved to have a relationship with TME. After WGCNA and LASSO, the CAFs-related module was identified, from which 21 gene signatures were confirmed. Then, a CDEGs-Score was constructed and its prediction efficiency in GC patients was conducted for validation. Overall, a highly precise nomogram was established for enhancing the adaptability of the CDEGs-Score. Furthermore, our findings revealed the applicability of CDEGs-Score in the sensitivity of chemotherapeutic drugs. In general, our research provided brand-new possibilities for comprehending HP-related GC, evaluating survival, and more efficient therapeutic strategies
Critical review on the thermal conductivity modelling of silica aerogel composites
As a new generation of thermal insulation materials, the effective thermal conductivity of aerogel and its composites is extremely low. The nanoporous structure of aerogels demobilises the movement of gas molecules, and the nano-skeleton system restricts solid heat transfer because of the size effect. Numerous research and modelling works have been carried out to understand and predict heat transfers. This review thoroughly discusses the existing theories and models of silica aerogel composites in gas, solid and radiative heat transfers. It investigates the correlation of the pore size distribution and solid skeleton network of the composites with the thermal conductivity. The review then assesses the advances of the development and questions remaining for further development, including 1) some unexplainable performance of existing models and 2) improvements required for gas and solid thermal conductivity models. Bridging the identified research gaps shall lead researchers to understand existing models better, develop a more accurate model based on more realistic microstructure simulation and further innovate the models for other emerging composites
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