| 1. |
- Gong, Hanmo, et al.
(författare)
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Gold nanoparticle transfer through photothermal effects in a metamaterial absorber by nanosecond laser
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 4, s. 6080-
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Tidskriftsartikel (refereegranskat)abstract
- A non-complicated, controllable method of metallic nanoparticle fabrication at low operating light power is proposed. The method is based on laser-induced forward transfer, using a metamaterial absorber as the donor to significantly enhance the photothermal effect and reduce the operating light fluence to 35 mJ/cm(2), which is much lower than that in previous works. A large number of metallic nanoparticles can be transferred by one shot of focused nanosecond laser pulses. Transferred nanoparticles exhibit good size uniformity and the sizes are controllable. The optical properties of transferred particles are characterized by dark-field spectroscopy and the experimental results agree with the simulation results.
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| 2. |
- Chen, Xi, et al.
(författare)
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Ordered Au nanocrystals on a substrate formed by light-induced rapid annealing
- 2014
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 6:3, s. 1756-1762
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Tidskriftsartikel (refereegranskat)abstract
- Light-induced rapid annealing (LIRA) is a widely used method to modify the morphology and crystallinity of noble metal nanoparticles, and the nanoparticles generally evolve into nanospheres. It is rather challenging to form faceted Au nanocrystals on a substrate using LIRA. Here the formation of spatially ordered Au nanocrystals using a continuous wave infrared laser is reported, assisted by a metamaterial perfect absorber. Faceted Au nanocrystals in truncated-octahedral or multi-twinned geometries can be obtained. The evolution of morphology and crystallinity of the Au nanoparticles during laser annealing is also revealed, where the crystal grain growth and the surface melting are shown to play key roles in nanocrystal formation. The evolution of morphology also gives the freedom of tuning the absorption spectrum of the metamaterial absorber. These findings provide a novel way for tailoring the morphology and crystallinity of metallic nanoparticles and may pave the way to fabricate refined nano-devices in many potential applications for optics, electronics, catalysis, surface-chemistry and biology.
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| 3. |
- Jun, Chen, et al.
(författare)
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A Novel Acceleration Data Compression Scheme for Wireless Sensor Network Application in Fresh Food Tracking System
- 2009
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Ingår i: The Ninth International Conference on Electronic Measurement & Instruments ICEMI’2009. - : IEEE Press. - 9781424438631 ; , s. 3-1-3-5
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Konferensbidrag (refereegranskat)abstract
- An enhanced dual-layer wide area wireless sensor network (WSN) system was developed and applied in fresh food tracking application. The sensor nodes of WSN provide a set of useful measurements about the environmental conditions during the fresh food transportation. Since the 3-axis acceleration data in such application account for more than 99% out of all collected source data, we propose a novel acceleration data compression scheme for this specific application, to overcome the resource and cost limitation imposed on embedded sensing nodes and wireless communication links in WSN. According to general fresh food transport behavior pattern, the acceleration data can be extracted into three components (D waveform, A waveform and P waveform). Each component could be compressed separately according to its distinct characteristic and then packetized as an encoded frame. In this paper we examine the experimental acceleration dataset from a field test (fresh melon fruit transport from Brazil to Sweden in 20 days) as a test case. Experimental results show that a high compression ratio (around 10:1) with the acceptable distortion could be achieved, confirming the effectiveness of the compression scheme proposed in this work.
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| 4. |
- Li, Suyang, et al.
(författare)
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Highly homogeneous bimetallic core-shell Au@Ag nanoparticles with embedded internal standard fabrication using a microreactor for reliable quantitative SERS detection
- 2023
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Ingår i: Materials Chemistry Frontiers. - : Royal Society of Chemistry (RSC). - 2052-1537. ; 7:6, s. 1100-1109
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Tidskriftsartikel (refereegranskat)abstract
- Bimetallic gold core-silver shell (Au@Ag) surface-enhanced Raman scattering tags draw broad interest in the fields of biological and environmental analyses. Herein, an efficient hybrid microfluidic chip was designed to prepare uniform Au@Ag core-shell nanoparticles, and DTNB was used as the internal standard tag molecule to prepare Au@DTNB@Ag for SERS detection. Homogeneous core-shell nanoparticles with a particle size of 90 nm were prepared by mixing a silver precursor and a gold core in a microfluidic chip. The relative standard deviation (RSD) of the particle size distribution was close to 10%, and the detection limit of 4-MBA was as low as 10-10 M. In order to solve the influence of SERS signal fluctuation, a uniform Au@DTNB@Ag core-molecule-shell structure was synthesized in a microfluidic chip, and the characteristic peak of the analyte was corrected by the relative intensity of the DTNB characteristic peak (1335 cm−1). The experimental results showed that the SERS detection was achieved with high reproducibility, and the SERS peak intensity had a good linear correlation with the concentration. The homogeneous SERS substrate prepared using a microfluidic chip has potential for sensitive and reliable detection of environmental chemical contaminants.
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| 5. |
- Pang, Zhibo, et al.
(författare)
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Global Fresh Food Tracking Service Enabled by Wide Area Wireless Sensor Network
- 2010
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Ingår i: 2010 IEEE Sensors Applications Symposium, SAS 2010. - : IEEE Sensors Council. ; , s. 6-9
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Konferensbidrag (refereegranskat)abstract
- A global fresh food tracking service is presented, in which a set of primary environmental conditions for transport of fresh fruits and vegetables, including global position, temperature, relative humidity, concentrations of CO2, O2 and ethylene gases and 3-axis acceleration, is collected through mobile and remotely controllable wireless sensor nodes. Real time monitoring, tracking, alarming, close-loop controlling and information sharing could therefore be provided as WEB services with service oriented architecture. Fully functioned hardware modules, protocols and system software have been developed. A 50-day field test has been successfully carried out, proving the system concept and the robustness of hardware and software designed. Due to its worldwide deploy-ability and added-values to fresh food supply chain, it is feasible to establish a practical fresh food tracking service business.
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| 6. |
- Pang, Zhibo, et al.
(författare)
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Mobile and Wide Area Deployable Sensor System for Networked Services
- 2009
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Ingår i: 2009 IEEE SENSORS. - NEW YORK : IEEE. - 9781424445486 ; , s. 1329-1332
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Konferensbidrag (refereegranskat)abstract
- A mobile and wide area deployable wireless sensor system, including hardware and software, is developed to enhance the mobility, deployment and capability of wireless sensors for networked services. Due to the dual-layer dual-directional wireless communication capability of a novel WAN-SAN coherent architecture and the removal of fix-installed gateway, all sensor nodes are remotely controllable and seamlessly integrated to internet services. Hardware modules are optimized for ultra low power and compact size. Abstract and extendable application interface is developed, based on SMS and TCP/UDP protocol, to be integrated easily into existing service systems. Hierarchical CPS-LPS Adaptive Localization, is supported based on CPS, wireless cellular ID, RFID, IR-UWB and inertial prediction. Specific data compression technique is adopted for high density data source. Finally, Fresh Food Tracking service is presented as an application example, including some field test data.
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| 7. |
- Tang, Wankai, et al.
(författare)
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Path Loss Modeling and Measurements for Reconfigurable Intelligent Surfaces in the Millimeter-Wave Frequency Band
- 2022
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Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778 .- 1558-0857. ; 70:9, s. 6259-6276
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Tidskriftsartikel (refereegranskat)abstract
- Reconfigurable intelligent surfaces (RISs) provide an interface between the electromagnetic world of wireless propagation environments and the digital world of information science. Simple yet sufficiently accurate path loss models for RISs are an important basis for theoretical analysis and optimization of RIS-assisted wireless communication systems. In this paper, we refine our previously proposed free-space path loss model for RISs to make it simpler, more applicable, and easier to use. The impact of the antenna's directivity of the transmitter, receiver, and the unit cells of the RIS on the path loss is explicitly formulated as an angle-dependent loss factor. The refined model gives more accurate estimates of the path loss of RISs comprised of unit cells with a deep sub-wavelength size. Based on the proposed model, the properties of a single unit cell are evaluated in terms of scattering performance, power consumption, and area, which allows us to unveil fundamental considerations for deploying RISs in high frequency bands. Two fabricated RISs operating in the millimeter-wave (mmWave) band are utilized to carry out a measurement campaign. The measurement results are shown to be in good agreement with the proposed path loss model. In addition, the experimental results suggest an effective form to characterize the power radiation pattern of the unit cell for path loss modeling.
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| 8. |
- Wang, Wei, et al.
(författare)
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Grating-assisted enhanced optical transmission through a seamless gold film
- 2014
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Ingår i: Optics Express. - 1094-4087. ; 22:5, s. 5416-5421
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we experimentally demonstrate enhanced optical transmission through a seamless gold film based on the grating-insulator-metal (GIM) architecture. The transmittance of this GIM structure reaches 40% at 930 nm, showing 3.7 dB and 9.1 dB increase compared with a bare gold film and a continuous metal-insulator-metal stack, respectively. The enhanced transmission is polarization-sensitive and robust for oblique incidence. With tunable transmission peaks, such a device exhibits great potential for applications in optical filtering, polarization detecting and further integration in optoelectronics system.
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| 9. |
- Zhang, Zhi, et al.
(författare)
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Two-layered wireless sensor networks for warehouses and supermarkets
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The rapid development of wireless sensor network and RFID technologies offers a wide range of novel applications and services. In this paper, we present a two-layered wireless network for warehouses and supermarkets to monitor goods storage and sale, and assist for quality management and market analysis. The hierarchical architecture uses IEEE 802.15.4a impulse ultra-wideband radio (IR-UWB) communication protocol between slave sensor nodes and master sensor nodes, and IEEE 802.11b/g between master sensor nodes and server. The performance of our proposal is evaluated based on the widely used OMNeT++ simulation environment. Simulation results are presented and discussed according to different sampling rates and traffic loads for specific scenarios requirements. © 2009 IEEE.
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| 10. |
- Zhao, Ding, et al.
(författare)
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Ultra-narrow-band light dissipation by a stack of lamellar silver and alumina
- 2014
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 104:22
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Tidskriftsartikel (refereegranskat)abstract
- An ultra-narrow band absorber consisting of continuous silver and alumina films is investigated. Owing to Fabry–Pérot resonance and silver's inherent loss, an ultra-narrow spectral range of light can be entirely trapped in the structure. By varying thicknesses of metallic and dielectric films, absorption peak shifts in visible and near-infrared regions. When two such metal-insulator-metal stacks are cascaded, experimental results show that an ultra-narrow absorption bandwidth of 7 nm is achieved, though theoretical results give that of 2 nm. Features of high-efficiency and ultra-narrow band absorption have huge potential in optical filtering, thermal emitter design, etc.
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