- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2018
- real- time object detection
- smartphone
- ancient architecture feature
- deep learning
- convolution neural network
- SSD-Mobilenet
- Optoelectronic Information Science and Engineering
- Dalian University of Technology
- The Palace Museum
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Enhancing THz Emission using a Shallow-Bounce Configuration
摘要： THz radiation promises to revolutionise applications in fields from security and counter terrorism, to medicine and agriculture. In the drive to develop robust, powerful and frequency-tunable THz laser sources, systems based on the stimulated polariton scattering (SPS) process, derived from solid state architectures, are arguably at the forefront. Within the realm of THz-SPS lasers, there are significant opportunities to enhance the performance of these systems, through careful consideration of the system architecture. It is well known that SPS-active crystals are inherently highly absorbing in the THz frequency range. This presents a dilemma in that while these crystals are capable of optically generating THz radiation, they are also the greatest cause of THz loss within these systems. This has led to system architectures/designs such as the surface-emitting configuration, which place the THz generation region as close to the emitting surface as possible. While this design has proven effective, it is but one consideration in maximising the possible THz power emitted from these systems. Of great relevance is the overall generation volume, its proximity to the emitting surface, and how this evolves with THz frequency tuning. Here, we report both computational modelling and experimental results contrasting the use of a new, novel, shallow-bounce architecture, in comparison to conventional linear and surface-emitting designs; the architecture of each is shown in Fig. 1. The shallow bounce system is shown schematically in Fig. 2. The system comprises a diode-end-pumped 0.3 at. % Nd:YVO4 laser crystal generating a fundamental field at 1342 nm. A flat end-mirror (M1), an x-cut 5 at. % MgO:LiNbO3 SPS crystal (HC Photonics Corp.) and a concave high reflectivity (HR) mirror (M2, radius of curvature (ROC) = 1000 mm) defined the ends of the fundamental resonator. The MgO:LiNbO3 crystal had dimensions of 5×5×20 mm3, and was AR coated on both end surfaces (R < 0.2 % at 1340 – 1380 nm at normal incidence). The system was Q-switched to achieve pulsed operation at a repetition rate of 5 kHz. A separate pair of HR mirrors (M3 and M4, ROC = 1000 mm; R = 99.9 % from 1340 – 1380 nm) were used to construct a 95 mm-long resonator which oscillated and bounced the Stokes field at the same TIR surface position as the fundamental field. Two high-resistivity Si-prisms with angles of 33°/33°/114° (dimensions 6×6×10 mm3) were placed in close proximity to the Teflon-coated polished x-z surface of the MgO:LiNbO3 crystal. These prisms extracted two THz beams at angles of ~ ± 30°relative to the TIR surface. The bounce angle of the fundamental field is 84.5 o (to the crystal normal), in comparison to 65 o which is typical in surface-emitting configurations. The shallow-bounce system generated dual-beam THz emission (with similar output powers and beam profiles) with a total, maximum average power of 67.5 (cid:541)(cid:58) for an incident CW pump power of 15.1 W. Notably, the frequency-tuning range was broad, covering the range 1.05 – 2.89 THz. High emission is maintained throughout this tuning range, especially in comparison to that achieved from linear and surface-emitting geometries, the details of which will be elucidated and discussed in this paper.
关键词： stimulated polariton scattering,THz-SPS lasers,shallow-bounce architecture,THz radiation,SPS
更新于2025-09-12 10:27:22
-
Efficient stable graphene-based perovskite solar cells with high flexibility in device assembling <i>via</i> modular architecture design
摘要： Carbon-based perovskite solar cells (C-PSCs) are emerging as low-cost stable photovoltaics. However, their power conversion efficiency (PCE) still lags behind that of devices based on Au or Ag as the current collector. Here, we introduced an innovative modular PSC design using a carbon back electrode, whose sheet resistance and thickness were greatly reduced by covering it with another carbon-coated FTO glass that was applied under pressure. We showed that these two individual elements could be assembled and separated repeatedly. Moreover, among the various commercial carbon sources (carbon black, graphite sheet, and graphene), graphene exhibited the best overall performance, showing the crucial importance of graphene as a charge collector. Power conversion efficiency (PCE) of 18.65% was achieved for graphene-based PSCs (G-PSCs), which was among the highest efficiency reported so far for C-PSCs. Moreover, the optimized devices without encapsulation retained 90% of their initial PCE after aging at an elevated temperature of 85 1C for 1000 h. Remarkably, G-PSCs showed significant structural flexibility; there was negligible degradation in PCE after repeated disassembling and assembling for more than 500 cycles. Our system provides a promising prospect for the facile repair and maintenance of PSCs via modular interconnections; related strategies may be extended to other devices.
关键词： modular architecture,stability,carbon-based,perovskite solar cells,flexibility,graphene
更新于2025-09-12 10:27:22
-
Analyte transport to micro- and nano-plasmonic structures
摘要： The study of optical affinity biosensors based on plasmonic nanostructures has received significant attention in recent years. The sensing surfaces of these biosensors have complex architectures, often composed of localized regions of high sensitivity (electromagnetic hot spots) dispersed along a dielectric substrate having little to no sensitivity. Under conditions such that the sensitive regions are selectively functionalized and the remaining regions passivated, the rate of analyte capture (and thus the sensing performance) will have a strong dependence on the nanoplasmonic architecture. Outside of a few recent studies, there has been little discussion on how changes to a nanoplasmonic architecture will affect the rate of analyte transport. We recently proposed an analytical model to predict transport to such complex architectures; however, those results were based on numerical simulation and to date, have only been partially verified. In this study we measure the characteristics of analyte transport across a wide range of plasmonic structures, varying both in the composition of their base plasmonic element (microwires, nanodisks, and nanorods) and the packing density of such elements. We functionalized each structure with nucleic acid-based bioreceptors, where for each structure we used analyte/receptor sequences as to maintain a Damk?hler number close to unity. This method allows to extract both kinetic (in the form of association and dissociation constants) and analyte transport parameters (in the form of a mass transfer coefficient) from sensorgrams taken from each substrate. We show that, despite having large differences in optical characteristics, measured rates of analyte transport for all plasmonic structures match very well to predictions using our previously proposed model. These results highlight that, along with optical characteristics, analyte transport plays a large role in the overall sensing performance of a nanoplasmonic biosensor.
关键词： mass transfer coefficient,analyte transport,plasmonic nanostructures,nanoplasmonic architecture,optical affinity biosensors
更新于2025-09-12 10:27:22
-
[IEEE 2019 IEEE Intelligent Vehicles Symposium (IV) - Paris, France (2019.6.9-2019.6.12)] 2019 IEEE Intelligent Vehicles Symposium (IV) - A decision-making architecture for automated driving without detailed prior maps
摘要： Autonomous driving requires general methods to generalize unpredictable situations and reason in complex scenarios where safety is critical and the vehicle must react in a reliable manner. In this sense, digital maps are a crucial component for relating the location of the vehicle and identifying the different road features. In this work, we present a decision-making architecture which does not require detailed prior maps. Instead, OSM is used to plan a global route and an automatically generated driving corridors, which are adapted using a proposed vision-based algorithm. Moreover, a grid-based approach is also applied to consider the localization uncertainty. Those self-generated driving corridors are used by the local planner to plan the trajectories the vehicle will follow. Our approach integrates global, local and HMI components to provide the required functionalities for autonomous driving in a general manner.
关键词： grid-based approach,decision-making architecture,Autonomous driving,vision-based algorithm,OpenStreetMap
更新于2025-09-12 10:27:22
-
The Development of Biophotovoltaic Systems for Power Generation and Biological Analysis
摘要： Biophotovoltaic systems (BPVs) resemble microbial fuel cells, but utilise oxygenic photosynthetic microorganisms associated with an anode to generate an extracellular electrical current, which is stimulated by illumination. Study and exploitation of BPVs have come a long way over the last few decades, having benefited from several generations of electrode development and improvements in wiring schemes. Power densities of up to 0.5 W m?2 and the powering of small electrical devices such as a digital clock have been reported. Improvements in standardisation have meant that this biophotoelectrochemical phenomenon can be further exploited to address biological questions relating to the organisms. Here, we aim to provide both biologists and electrochemists with a review of the progress of BPV development with a focus on biological materials, electrode design and interfacial wiring considerations, and propose steps for driving the field forward.
关键词： photosynthesis,electrode architecture,fuel cells,biophotoelectrochemistry,biophotovoltaics
更新于2025-09-11 14:15:04
-
Articulated Laser Sensor for Three-Dimensional Precision Measurement
摘要： Breaking through the orthogonal shafting architecture of traditional measurement instruments, a novel articulated laser sensor for three-dimensional (3D) precision measurement is proposed. The novel sensor consists of two articulated laser sensing modules, and each module is mainly made up of two one-dimensional rotary tables and one collimated laser to achieve a ?exible angle intersection. Moreover, a high-resolution digital camera is mounted on the right sensing module to achieve vision guidance. The three axes of each sensing module represent a non-orthogonal shafting architecture. The requirements of structural design, material selection, processing technology, assembling, calibration and maintain are greatly lowered. The costs are greatly reduced, including time and money. The system architecture, parameter calibration and measurement principle are elaborated. An accurate intersection model of two laser beams is proposed to calculate the accurate rotation angles of rotary tables by discrete point interpolation method. The experimental results showed that a maximum error less than 0.05 mm was detected from 100 mm to 500 mm. It is proved that 3D precision measurement is feasible with this proposed articulated laser sensor.
关键词： Articulated laser sensor,accurate intersection model,non-orthogonal shafting architecture,3D precision measurement
更新于2025-09-11 14:15:04
-
Hybrid 0D/2D Ni2P quantum dot loaded TiO2(B) nanosheet photothermal catalysts for enhanced hydrogen evolution
摘要： The development of low cost, stable, robust photocatalysts to convert solar energy into hydrogen energy is an important challenge. Here, we describe a simple solvothermal method to successfully fabricate a catalyst with a hybrid 0D/2D Ni2P quantum dot/TiO2(B) nanosheet architecture. HRTEM shows that Ni2P quantum dots about 5 nm in size were dispersed on ultrathin TiO2(B) nanosheets. The optimum photocatalytic H2 evolution rate with 10 wt% Ni2P/TiO2(B) (3.966 mmol g?1 h?1), which was 15 times higher than pure TiO2(B) nanosheets. Significantly, the new catalyst shows high stability and reusability in multiply cycled H2 production runs for a 30 h period. The H2 production rate can be considerably increased furthered by using synergistic photothermal H2 evolution (20.129 mmol g?1 h?1 at 90 °C).
关键词： TiO2(B) nanosheets,Photocatalytic H2 evolution,Ni2P quantum dots,0D/2D architecture,Synergistic photothermal catalysis
更新于2025-09-11 14:15:04
-
3D Printing of Highly Conductive Silver Architectures Enabled to Sinter at Low Temperatures
摘要： Silver (Ag) nanoparticle-based inks are frequently used in printed electronics to form conductive patterns, but often require high-temperature sintering to achieve the optimum electrical conductivity, hindering their use in substrates with poor heat resistance. Herein, a three-dimensional (3D) printing strategy to produce highly conductive Ag 3D architectures that can be sintered at low temperatures is reported. This strategy is based on the additive deposition of Ag nanoparticles and microflakes via extrusion-based 3D printing with the Ag ink that involves poly(acrylic acid) (PAA)-stabilized Ag nanoparticles, Ag microflakes, and NaCl - a destabilizing agent. The designed Ag inks are stable and suitable for ink-extrusion 3D printing. In chemical sintering, Cl- can detach PAA from the Ag nanoparticle surface, enabling nanoparticle coalescence and sintering. An elevated annealing temperature induces increased NaCl density in the printed patterns and accelerates the surface and grain boundary diffusion of Ag atoms, contributing to enhance chemical sintering. On annealing at ~110 °C for 30 min, the printed structures exhibited an electrical conductivity of ~9.72 × 104 S cm–1, which is ~15.6% of that of bulk Ag. Complicated Ag architectures with diverse shapes were successfully fabricated on polymeric substrates. Several structural electronic applications were demonstrated by hybrid 3D printing combining our extrusion-based 3D printing and conventional fused deposition modeling (FDM).
关键词： Conductive inks,3D printing,3D printed electronics,Low temperature,Silver 3D architecture,Chemical sintering
更新于2025-09-11 14:15:04
-
Analysis of Changes in Oil Palm Canopy Architecture From Basal Stem Rot Using Terrestrial Laser Scanner
摘要： Basal stem rot (BSR), caused by the Ganoderma fungus, is an infectious disease that affects oil palm (Elaeis guineensis) plantations. BSR leads to a significant economic loss and reductions in yields of up to Malaysian Ringgit (RM) 1.5 billion (US$400 million) yearly. By 2020, the disease may affect ~1.7 million tonnes of fresh fruit bunches. The plants appear symptomless in the early stages of infection, although most plants die after they are infected. Thus, early, accurate, and nondestructive disease detection is crucial to control the impact of the disease on yields. Terrestrial laser scanning (TLS) is an active remote-sensing, noncontact, cost-effective, precise, and user-friendly method. Through high-resolution scanning of a tree’s dimension and morphology, TLS offers an accurate indicator for health and development. This study proposes an efficient image processing technique using point clouds obtained from TLS ground input data. A total of 40 samples (10 samples for each severity level) of oil palm trees were collected from 9-year-old trees using a ground-based laser scanner. Each tree was scanned four times at a distance of 1.5 m. The recorded laser scans were synched and merged to create a cluster of point clouds. An overhead two-dimensional image of the oil palm tree canopy was used to analyze three canopy architectures in terms of the number of pixels inside the crown (crown pixel), the degree of angle between fronds (frond angle), and the number of fronds (frond number). The results show that the crown pixel, frond angle, and frond number are significantly related and that the BSR severity levels are highly correlated (R2 = 0.76, P < 0.0001; R2 = 0.96, P < 0.0001; and R2 = 0.97, P < 0.0001, respectively). Analysis of variance followed post hoc tests by Student–Newman–Keuls (Newman–Keuls) and Dunnett for frond number presented the best results and showed that all levels were significantly different at a 5% significance level. Therefore, the earliest stage that a Ganoderma infection could be detected was mildly infected (T1). For frond angle, all post hoc tests showed consistent results, and all levels were significantly separated except for T0 and T1. By using the crown pixel parameter, healthy trees (T0) were separated from unhealthy trees (moderate infection [T2] and severe infection [T3]), although there was still some overlap with T1. Thus, Ganoderma infection could be detected as early as the T2 level by using the crown pixel and the frond angle parameters. It is hard to differentiate between T0 and T1, because during mild infection, the symptoms are highly similar. Meanwhile, T2 and T3 were placed in the same group, because they showed the same trend. This study demonstrates that the TLS is useful for detecting low-level infection as early as T1 (mild severity). TLS proved beneficial in managing oil palm plantation disease.
关键词： Ganoderma,LiDAR,crown,frond,oil palm architecture
更新于2025-09-11 14:15:04
-
The Effect of Eye Patching on Clear Corneal Incision Architecture in Phacoemulsification: A Randomized Controlled Trial
摘要： To investigate the effects of postoperative eye patching on clear corneal incision architecture in phacoemulsification. Design: A single?center, randomized controlled trial. Methods: A total of 132 patients with uncomplicated phacoemulsification were randomly allocated to the intervention or control group. The intervention group received postoperative eye patching for approximately 18 hours, whereas the control group received eye shield. The clear corneal incision architecture was examined postoperatively at 2 hours, 1 day, and 7 days after surgery using optical coherence tomography. Results: Epithelial gaping was significantly reduced on postoperative day 1 in the intervention group (52.4%) compared with control (74.2%) (P = 0.01). No differences were found for other architectural defects. Descemet membrane detachment was associated with lower intraocular pressure on postoperative day 7 (P = 0.02). Presence of underlying diabetes mellitus did not seem to influence architectural defects. Conclusions: Postoperative eye patching facilitated epithelial healing and reduced the occurrence of epithelial gaping on postoperative day 1. It may play a role in protecting and improving corneal wounds during the critical immediate postoperative period.
关键词： epithelial gaping,clear corneal incision,architecture,eye patching,phacoemulsification
更新于2025-09-11 14:15:04