| 1. |
- Chen, Lan, et al.
(författare)
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Mechanism for negative differential resistance in molecular electronic devices : Local orbital symmetry matching
- 2007
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 99:14
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Tidskriftsartikel (refereegranskat)abstract
- A new mechanism for negative differential resistance (NDR) originating from local orbital symmetry matching between an electrode and a molecule in a single molecular electronic device is proposed and demonstrated by a joint experimental and theoretical scanning tunneling microscope study of a cobalt phthalocyanines (CoPc) molecule on a gold substrate. For two different metal tips used, Ni and W, NDR occurs only with Ni tips and shows no dependence on the geometrical shape of the tip. Calculations reveal that such a behavior is a result of local orbital symmetry matching between the Ni tip and Co atom.
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| 2. |
- Chen, Taolue, et al.
(författare)
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A Decision Procedure for Path Feasibility of String Manipulating Programs with Integer Data Type
- 2020
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Ingår i: ATVA 2020. - Cham : Springer Nature. - 9783030591519 - 9783030591526 ; , s. 325-342
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose a decision procedure for a class of string-manipulating programs which includes not only a wide range of string operations such as concatenation, replaceAll, reverse, and finite transducers, but also those involving the integer data-type such as length, indexof, and substring. To the best of our knowledge, this represents one of the most expressive string constraint languages that is currently known to be decidable. Our decision procedure is based on a variant of cost register automata. We implement the decision procedure, giving rise to a new solver OSTRICH+. We evaluate the performance of OSTRICH+ on a wide range of existing and new benchmarks. The experimental results show that OSTRICH+ is the first string decision procedure capable of tackling finite transducers and integer constraints, whilst its overall performance is comparable with the state-of-the-art string constraint solvers.
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| 3. |
- Feng, Feng, et al.
(författare)
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Room-temperature large magnetic-dielectric coupling in new phase anatase VTiO4
- 2013
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 49:89, s. 10462-10464
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Tidskriftsartikel (refereegranskat)abstract
- The synthetic new-phase VTiO4, as a new solid solution structure of anatase type, brings a large magnetodielectric ratio (Delta epsilon/epsilon(0)) of 7.2% at 300 K, representing a new simple-oxide structural catalogue exhibiting a room-temperature large magnetic-dielectric effect.
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| 4. |
- Feng, Jun, et al.
(författare)
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Giant Moisture Responsiveness of VS2 Ultrathin Nanosheets for Novel Touchless Positioning Interface
- 2012
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 24:15, s. 1969-1974
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Tidskriftsartikel (refereegranskat)abstract
- Utilizing a thin film of VS2 ultrathin nanosheets with giant and fast moisture responsiveness, a brand-new model of moisture-based positioning interface is put forward here, by which not only the 2D position information of finger tips can be acquired, but also the relative height can be detected as the third dimensionality, representing a promising platform for advanced man-machine interactive systems.
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| 5. |
- Hu, Siyuan, et al.
(författare)
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Numerical and Experimental Study on Laminar Methane/Air Premixed Flames at Varying Pressure
- 2017
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 105, s. 4970-4975
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Tidskriftsartikel (refereegranskat)abstract
- Laminar methane/air premixed Bunsen flames were studied using detailed numerical simulations and laser diagnostics. In the numerical simulations one-dimensional and two-dimensional configurations were considered with detailed transport properties and chemical kinetic mechanism. In the measurements OH PLIF was employed. The flame structures vary with varying equivalence ratio and pressure. For stoichiometric mixture at atmospheric pressure the flame exhibits a single reaction zone structure, while at high-pressures the flame exhibits a two-reaction zone structure: an inner premixed flame and an outer diffusion flame. The predicted two-zone structure is confirmed in the OH PLIF measurements. Using the numerical and the experimental data the methods of flame-cone-angle and flame-area have been used to extract the laminar flame speed for different equivalence ratios and pressures. It is found that although the flame cone angle method is widely used, it yields a lower accuracy than that of the flame surface area method. The inlet velocity of the burner is shown to affect the accuracy of extracted laminar flame speed. It is suggested that the most suitable inlet velocity of methane-air mixture is about 6 times the laminar flame speed.
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| 6. |
- Jia, Shi, et al.
(författare)
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0.4 THz Photonic-Wireless Link with 106 Gbit/s Single Channel Bitrate
- 2018
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Ingår i: Journal of Lightwave Technology. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0733-8724 .- 1558-2213. ; 36:2, s. 610-616
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Tidskriftsartikel (refereegranskat)abstract
- To accommodate the demand of exponentially increased global wireless data traffic, the prospective data rates for wireless communication in the market place will soon reach 100 Gbit/s and beyond. In the lab environment, wireless transmission throughput has been elevated to the level of over 100 Gbit/s attributed to the development of photonic-assisted millimeter wave (MMW) and THz technologies. However, most of recent demonstrations with over 100 Gbit/s data rates are based on spatial or frequency division multiplexing techniques, resulting in increased system's complexity and energy consumption. Here, we experimentally demonstrate a single channel 0.4 THz photonic-wireless link achieving a net data rate of beyond 100 Gbit/s by using a single pair of THz emitter and receiver, without employing any spatial/frequency division multiplexing techniques. The high throughput up to 106 Gbit/s within a single THz channel is enabled by combining spectrally efficient modulation format, ultra-broadband THz transceiver and advanced digital signal processing (DSP) routine. Besides that, our demonstration from system-wide implementation viewpoint also features high transmission stability, and hence shows its great potential to not only decrease the system's complexity, but also meet the requirements of prospective data rates for bandwidth-hungry short-range wireless applications.
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| 7. |
- Lin, Chenwen, et al.
(författare)
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Hydrogen-Incorporated TiS2 Ultrathin Nanosheets with Ultrahigh Conductivity for Stamp-Transferrable Electrodes
- 2013
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 135:13, s. 5144-5151
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Tidskriftsartikel (refereegranskat)abstract
- As a conceptually new class of two-dimensional (2D) materials, the ultrathin nanosheets as inorganic graphene analogues (IGAs) play an increasingly vital role in the new-generation electronics. However, the relatively low electrical conductivity of inorganic ultrathin nanosheets in current stage significantly hampered their conducting electrode applications in constructing nanodevices. We developed the unprecedentedly high electrical conductivity in inorganic ultrathin nanosheets. The hydric titanium disulfide (HTS) ultrathin nanosheets, as a new IGAs, exhibit the exclusively high electrical conductivity of 6.76 x 10(4) S/m at room temperature, which is superior to indium tin oxide (1.9 x 10(4) S/m), recording the best value in the solution assembled 2D thin films of both graphene (5.5 x 10(4) S/m) and inorganic graphene analogues (5.0 x 10(2) S/m). The modified hydrogen on S-Ti-S layers contributes additional electrons to the TiS2 layered frameworks, rendering the controllable electrical conductivity as well as the electron concentrations. Together with synergic advantages of the excellent mechanical flexibility, high stability, and stamp-transferrable properties, the HTS thin films show promising capability for being the next generation conducting electrode material in the nanodevice fields.
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| 8. |
- Miao, Chiyuan, et al.
(författare)
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Hydrological Research Evolution: A Large Language Model-Based Analysis of 310,000 Studies Published Globally Between 1980 and 2023
- 2024
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Ingår i: Water resources research. - : American Geophysical Union (AGU). - 0043-1397 .- 1944-7973. ; 60:6
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Tidskriftsartikel (refereegranskat)abstract
- Hydrology plays a crucial role in understanding Earth's intricate water system and addressing water-related problems, including against the backdrop of ongoing climate change. A retrospective review of the evolution of hydrology up to the current state of research is of great importance for understanding this role. While there have been some quantitative reviews of large numbers of hydrological publications, there still remains a lack of overarching hydrological research assessment, particularly with the focus on hydrological basins as fundamental spatial-geographic units of hydrological analysis. Large language models, represented by OpenAI's ChatGPT, have demonstrated powerful textual understanding capabilities, making it possible to extract such overarching and basin information from hydrological publications. Here, we considered publications related to hydrology from Web of Science spanning January 1980 to October 2023, and parsed the information from this extensive body of literature by integrating a large language model and geocoding. These techniques enable quantitative analysis of research characteristics across different spatio-temporal scales, focusing on hotspot topics, collaboration networks, and various basins worldwide. Our study revealed an increase in hydrological research since the 1990 s, with shifts in research priorities from groundwater and nutrients to climate change and ecohydrology. Some basins in North America and Europe have consistently been hotspots for hydrological research. Since the 2010s, there has been a noteworthy increase in interest toward basins in China and South Asia, but attention to many regions with frequent extreme rainfall remains insufficient. Geographical patterns show different preferred research topics for different basins, but climate change has emerged as the most prominent topic across all regions in the last decade. In conclusion, our study provides an effective approach to quantitative analysis of research trends, offering a fresh view on the evolution of hydrology as a research field, its focus on various hydrological basins around the world, and the emergence of overarching and basin-specific hot topics over time.
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| 9. |
- Xu, Kun, et al.
(författare)
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Highly entangled K0.5V2O5 superlong nanobelt membranes for flexible nonvolatile memory devices
- 2012
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 22:35, s. 18214-18220
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Tidskriftsartikel (refereegranskat)abstract
- Flexible electronics has been an intensively pursued hot topic in recent years, and flexible nonvolatile memory devices (NVMs) are also an important concept in modern electronics due to the advantages of retaining stored information even when not powered, with great portability and high deformability. In this study, we report that delta-K0.5V2O5 bronze with sandwiched potassium atoms in the V-O framework has been found to be a new promising material platform for intriguing nonvolatile memory applications. The bronze structure with the sandwiched alkali metal atoms between the two V2O5 layers ensures the promising NVM effect by changing the electronic properties under an applied electric field. The delta-K0.5V2O5 bronze entangled superlong nanobelt networks, which are established via the "solid-solution-solid" (SSS) mechanism and a hydrogen-bond-assisted entangling process, bring the synergic advantages of excellent mechanical and electrical properties. Spin polarized GGA+U density functional theory calculations elucidate well the nature of bronze-based NVM, in which the overall effect of applying an electric field is to reduce the energy gap, no matter what the direction of the electric field is; the effects of electric field and ion shift would follow the same trend, the non-linear band gap changes would lead to resistance changes of this material. The NVMs based on the entangled superlong nanobelt membrane possess the advantages of not only low cost and very simple device structure, but also a reversible and noticeable nonlinear hysteresis, low consumption, stable WRER cycles, and a long retention time over 1000 s, showing promise for next-generation flexible NVMs.
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| 10. |
- Zhan, Liangtong, et al.
(författare)
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Effects of multiscale heterogeneity on transport in three-dimensional fractured porous rock with a rough-walled fracture network
- 2022
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Ingår i: Computers and geotechnics. - : Elsevier BV. - 0266-352X .- 1873-7633. ; 148, s. 104836-
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Tidskriftsartikel (refereegranskat)abstract
- This study numerically analyzed the effect of multiscale heterogeneity on flow and transport response of a threedimensional (3D) fractured porous rock with rough-walled fracture network. 3D discrete fracture matrix (DFM) models with different heterogeneity scales (network-scale, fracture-to-fracture-scale, and individual fracture scale) were generated. The results showed that the velocity and concentration distributions among the different DFMs were highly variable due to multiscale heterogeneity. The cumulative distribution function curves (CDFs) of the concentration disctribution indicated that fracture-to-fracture-scale heterogeneity led to an earlier breakthrough time than network-scale heterogeneity, and this behavior was further enhanced by individual fracture-scale heterogeneity, suggesting that transport was accelerated by enhanced local channeling flow with increasing fracture roughness. The complementary cumulative distribution function curves (CCDFs) showed obvious long tailing as heterogeneity increased from fracture-to-fracture-scale to individual fracture-scale. Compared with the case where only network-scale heterogeneity was considered, the calculated downstream concentration with fracture-to-fracture-scale heterogeneity increased first from 0.670 to 0.709. However, the downstream concentration then decreased from 0.684 to 0.618 as the roughness increased from & USigma; = 0.03 mm to & USigma; = 0.07 mm. These results can help predict the migration behavior of radioactive nuclides in far-field areas and assess the long-term performance of deep geological repositories.
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