103 research outputs found
High-Precision Fruit Localization Using Active Laser-Camera Scanning: Robust Laser Line Extraction for 2D-3D Transformation
Recent advancements in deep learning-based approaches have led to remarkable
progress in fruit detection, enabling robust fruit identification in complex
environments. However, much less progress has been made on fruit 3D
localization, which is equally crucial for robotic harvesting. Complex fruit
shape/orientation, fruit clustering, varying lighting conditions, and
occlusions by leaves and branches have greatly restricted existing sensors from
achieving accurate fruit localization in the natural orchard environment. In
this paper, we report on the design of a novel localization technique, called
Active Laser-Camera Scanning (ALACS), to achieve accurate and robust fruit 3D
localization. The ALACS hardware setup comprises a red line laser, an RGB color
camera, a linear motion slide, and an external RGB-D camera. Leveraging the
principles of dynamic-targeting laser-triangulation, ALACS enables precise
transformation of the projected 2D laser line from the surface of apples to the
3D positions. To facilitate laser pattern acquisitions, a Laser Line Extraction
(LLE) method is proposed for robust and high-precision feature extraction on
apples. Comprehensive evaluations of LLE demonstrated its ability to extract
precise patterns under variable lighting and occlusion conditions. The ALACS
system achieved average apple localization accuracies of 6.9 11.2 mm at
distances ranging from 1.0 m to 1.6 m, compared to 21.5 mm by a commercial
RealSense RGB-D camera, in an indoor experiment. Orchard evaluations
demonstrated that ALACS has achieved a 95% fruit detachment rate versus a 71%
rate by the RealSense camera. By overcoming the challenges of apple 3D
localization, this research contributes to the advancement of robotic fruit
harvesting technology
Simultaneous ground-state cooling of multiple degenerate mechanical modes through cross-Kerr effect
Simultaneous ground-state cooling of multiple degenerate mechanical modes is
a tough issue in optomechanical system due to the existence of the dark mode
effect. Here we propose a universal and scalable method to break the dark mode
effect of two degenerate mechanical modes by introducing the cross-Kerr (CK)
nonlinearity. At most four stable steady states can be achieved in our scheme
in the presence of the CK effect, different from the bistable behavior of the
standard optomechanical system. Under the constant input laser power, the
effective detuning and mechanical resonant frequency can be modulated by the CK
nonlinearity, which results in an optimal CK coupling strength for cooling.
Similarly, there will be an optimal input laser power for cooling when the CK
coupling strength stays fixed. Our scheme can be extended to break the dark
mode effect of multiple degenerate mechanical modes by introducing more than
one CK effects. To fulfill the requirement of the simultaneous ground-state
cooling of N multiple degenerate mechanical modes N-1 CK effects with different
strengths are needed. Our proposal provides new insights in dark mode control
and might pave the way to manipulating of multiple quantum states in
macroscopic system.Comment: 5 pages, 4 figure
Aconitine and its derivatives: bioactivities, structure-activity relationships and preliminary molecular mechanisms
Aconitine (AC), which is the primary bioactive diterpene alkaloid derived from Aconitum L plants, have attracted considerable interest due to its unique structural feature. Additionally, AC demonstrates a range of biological activities, such as its ability to enhance cardiac function, inhibit tumor growth, reduce inflammation, and provide analgesic effects. However, the structure-activity relationships of AC are remain unclear. A clear understanding of these relationships is indeed critical in developing effective biomedical applications with AC. In line with these challenges, this paper summarized the structural characteristics of AC and relevant functional and bioactive properties and the structure-activity relationships presented in biomedical applications. The primary temporal scope of this review was established as the period spanning from 2010 to 2023. Subsequently, the objective of this review was to provide a comprehensive understanding of the specific action mechanism of AC, while also exploring potential novel applications of AC derivatives in the biomedical field, drawing upon their structural characteristics. In conclusion, this review has provided a comprehensive analysis of the challenges and prospects associated with AC in the elucidation of structure-bioactivity relationships. Furthermore, the importance of exploring modern biotechnology approaches to enhance the potential biomedical applications of AC has been emphasized
Decoding the spermatogonial stem cell niche under physiological and recovery conditions in adult mice and humans
The intricate interaction between spermatogonial stem cell (SSC) and testicular niche is essential for maintaining SSC homeostasis; however, this interaction remains largely uncharacterized. In this study, to characterize the underlying signaling pathways and related paracrine factors, we delineated the intercellular interactions between SSC and niche cell in both adult mice and humans under physiological conditions and dissected the niche-derived regulation of SSC maintenance under recovery conditions, thus uncovering the essential role of C-C motif chemokine ligand 24 and insulin-like growth factor binding protein 7 in SSC maintenance. We also established the clinical relevance of specific paracrine factors in human fertility. Collectively, our work on decoding the adult SSC niche serves as a valuable reference for future studies on the aetiology, diagnosis, and treatment of male infertility.</p
Optomechanically induced transparency and directional amplification in a non-Hermitian optomechanical lattice
Cavity optomechanics is important in both quantum information processing and
basic physics research. In this paper, we propose an optomechanical lattice
which manifests non-Hermitian physics . We first use the non-Bloch band theory
to investigate the energy spectrum and transmission property of an
optomechanical lattice. The generalized Brillouin zone of the system is
calculated with the help of the resultant. And the periodical boundary
condition (PBC) and open boundary condition energy spectrum are given,
subsequently. By introducing probe laser on different sites we observed the
directional amplification of the system. The direction of the amplification is
analyzed combined with the non-Hermitian skin effect. The frequency that
supports the amplification is analyzed by considering the PBC energy spectrum.
By introducing probe laser on one site we investigate the onsite transmission
property. Optomechanically induced transparency (OMIT) can be achieved in our
system. By varying the parameters and size of the system, the OMIT peak can be
effectively modulated or even turned into optomechanically induced
amplification . Our system shows its potential as the function of a single-way
signal filter. And our model can be extended to other non-Hermitian Bosonic
model which may possess topological features and bipolar non-Hermitian skin
effect.Comment: 10pages,6 figure
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