| 1. |
- Hakonen, Aron, 1970, et al.
(författare)
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Hand-Held Femtogram Detection of Hazardous Picric Acid with Hydrophobic Ag Nanopillar SERS Substrates and Mechanism of Elasto-Capillarity
- 2017
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Ingår i: ACS Sensors. - : American Chemical Society (ACS). - 2379-3694. ; 2:2, s. 198-202
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Tidskriftsartikel (refereegranskat)abstract
- Picric acid (PA) is a severe environmental and security risk due to its unstab e, toxic, and explosive properties. It is also challenging to detect in trace amounts and in situ because of its highly acidic and anionic character. Here, we assess sensing of PA under nonlaboratory conditions using surface-enhanced Raman scattering (SERS) silver nanopillar substrates and handheld Raman spectroscopy equipment. The advancing elasto-capillarity effects are explained by molecular dynamics simulations. We obtain a SERS PA detection limit on the order of 20 ppt, corresponding attomole amounts, which together with the simple analysis methodology demonstrates that the presented approach is highly competitive for ultrasensitive analysis in the field.
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| 2. |
- Müser, M. H., et al.
(författare)
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Meeting the Contact-Mechanics Challenge
- 2017
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Ingår i: Tribology letters. - : Springer New York LLC. - 1023-8883 .- 1573-2711. ; 65:4
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Tidskriftsartikel (refereegranskat)abstract
- This paper summarizes the submissions to a recently announced contact-mechanics modeling challenge. The task was to solve a typical, albeit mathematically fully defined problem on the adhesion between nominally flat surfaces. The surface topography of the rough, rigid substrate, the elastic properties of the indenter, as well as the short-range adhesion between indenter and substrate, were specified so that diverse quantities of interest, e.g., the distribution of interfacial stresses at a given load or the mean gap as a function of load, could be computed and compared to a reference solution. Many different solution strategies were pursued, ranging from traditional asperity-based models via Persson theory and brute-force computational approaches, to real-laboratory experiments and all-atom molecular dynamics simulations of a model, in which the original assignment was scaled down to the atomistic scale. While each submission contained satisfying answers for at least a subset of the posed questions, efficiency, versatility, and accuracy differed between methods, the more precise methods being, in general, computationally more complex. The aim of this paper is to provide both theorists and experimentalists with benchmarks to decide which method is the most appropriate for a particular application and to gauge the errors associated with each one..
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| 3. |
- Zhang, Lu, et al.
(författare)
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Hybrid fiber–THz fronthaul supporting up to 16384-QAM-OFDM with the delta-sigma modulation
- 2022
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Ingår i: Optics Letters. - : Optica Publishing Group (formerly OSA). - 0146-9592 .- 1539-4794. ; 47:17, s. 4307-4310
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Tidskriftsartikel (refereegranskat)abstract
- With the progress of high-capacity radio access networks, ultra-dense small cells are rapidly being deployed in urban areas. As a result, the deployment of a large number of optical fibers in urban areas becomes a severe issue. In this Letter, we propose a hybrid fiber–terahertz (THz) mobile fronthaul system supporting flexible and high-order wireless signal transmission with the delta-sigma modulation. The photonic THz transmission is used as the seamless extension of fiber-based fronthaul in small cells. A 20-Gbit/s digital fiber–THz fronthaul system is experimentally demonstrated to validate the proposed scheme, with 10-km optical fiber transmission and 300-GHz wireless relay. Carrier aggregation of up to 10 40-MHz and 60-MHz 5G-new radio (5G-NR) channels at the radio carrier frequency of 3.9 GHz is reported. The design of quantization noise suppressed delta-sigma modulation enables the system to transmit orthogonal frequency division multiplexing (OFDM) modulation up to 16384 order quadrate amplitude modulation (QAM) mapping with the error vector magnitude (EVM) below 0.5%.
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| 4. |
- Zhang, L., et al.
(författare)
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Quantum Noise Secured Terahertz Communications
- 2023
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : Institute of Electrical and Electronics Engineers Inc.. - 1077-260X .- 1558-4542. ; 29:5
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Tidskriftsartikel (refereegranskat)abstract
- The terahertz communications display an important role in high-speed wireless communications, the security threat from the eavesdroppers in the terahertz communications has been gaining attention recently. The true randomness in the physical layer can ensure one-time-pad encryption for secured terahertz communications, however, physical layer security schemes like the quantum key distribution methods suffer from device imperfections that limit the desirable signal rate and link distance. Herein, we present the quantum noise secured terahertz wireless communications with photonic terahertz signal generation schemes. With the high-order diffusion algorithms, the signal is masked by the quantum noise ciphers to the eavesdroppers and cannot be detected because the inevitable randomness by quantum noise measurement will cause physical measurement errors. In the experiment, we demonstrate 16 Gbits-1 quantum noise secured terahertz wireless communications with the conventional optical communication realms and devices, operating at 300 GHz terahertz frequency. This quantum noise secured terahertz communication approach is a significant step toward high-security wireless communications.
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