- 标题
- 摘要
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- 实验方案
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Hydrophilic Poly(vinylidene Fluoride) Film with Enhanced Inner Channels for Both Water- and Ionic Liquid-Driven Ion-Exchange Polymer Metal Composite Actuators
摘要： This study presents a novel and facile strategy to fabricate a hydrophilic poly(vinylidene fluoride) (PVDF) electrolyte film with enhanced inner channels for a high-performance and cost-effective ion-exchange polymer metal composite (IPMC) actuator. The resultant PVDF composite film is composed of hierarchical micro/nanoscale structures: well-defined polymer grains with a diameter of ～20 μm and much finer particles with a diameter of ～390 nm, producing three-dimensional interconnected, hierarchical inner channels to facilitate ion migration of the electrolyte matrix film has a high porosity of 15.8% and yields a high water uptake of 44.2% and an ionic liquid (IL, [EMIm]·[BF4]) uptake of 38.1% to make both water-driven and IL-driven IPMC actuators because of the introduction of polar polyvinyl pyrrolidone. Compared to the conventional PVDF/IL-based IPMC, both water-driven and IL-driven PVDF-based IPMCs exhibit high ion migration rates, thus effectively improving the actuation frequency and producing remarkably higher levels of actuation force and displacement. Specifically, the force outputs are increased by 13.4 and 3.0 folds, and the displacement outputs are increased by 2.2 and 1.9 folds. Using an identical electrolyte matrix, water-driven IPMC exhibits stronger electromechanical performance, benefiting to make IPMC actuator with high levels of force and power outputs, whereas IL-driven IPMC exhibits a more stable electromechanical performance, benefiting to make long lifetime IPMC actuator in air. Thus, the resultant IPMCs are promising in the design of artificial muscles with tunable electromechanical performance for flexible actuators or displacement/vibration sensors at low cost.
关键词： ionic exchange polymer metal composite (IPMC),ionic liquid (IL),poly(vinylidene fluoride) (PVDF),inner channel,electromechanical response,polyvinyl pyrrolidone (PVP)
更新于2025-09-23 15:23:52
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Analysis of trajectory similarity and configuration similarity in on-the-fly surface-hopping simulation on multi-channel nonadiabatic photoisomerization dynamics
摘要： We propose an “automatic” approach to analyze the results of the on-the-fly trajectory surface hopping simulation on the multi-channel nonadiabatic photoisomerization dynamics by considering the trajectory similarity and the configuration similarity. We choose a representative system phytochromobilin (PΦB) chromophore model to illustrate the analysis protocol. After a large number of trajectories are obtained, it is possible to define the similarity of different trajectories by the Fréchet distance and to employ the trajectory clustering analysis to divide all trajectories into several clusters. Each cluster in principle represents a photoinduced isomerization reaction channel. This idea provides an effective approach to understand the branching ratio of the multi-channel photoisomerization dynamics. For each cluster, the dimensionality reduction is employed to understand the configuration similarity in the trajectory propagation, which provides the understanding of the major geometry evolution features in each reaction channel. The results show that this analysis protocol not only assigns all trajectories into different photoisomerization reaction channels but also extracts the major molecular motion without the requirement of the pre-known knowledge of the active photoisomerization site. As a side product of this analysis tool, it is also easy to find the so-called “typical” or “representative” trajectory for each reaction channel.
关键词： trajectory similarity,multi-channel nonadiabatic photoisomerization dynamics,Fréchet distance,dimensionality reduction,phytochromobilin chromophore,on-the-fly surface-hopping simulation,configuration similarity,clustering analysis
更新于2025-09-23 15:23:52
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Investigation of RF and DC Performance of E-Mode In <sub/>0.80</sub> Ga <sub/>0.20</sub> As/InAs/In <sub/>0.80</sub> Ga <sub/>0.20</sub> as Channel based DG-HEMTs for Future Submillimetre Wave and THz Applications
摘要： In this paper, we systematically investigated the DC and RF behaviour of the novel Enhancement-Mode (E-Mode) Double-Gate High Electron Mobility Transistors (DGHEMTs) using Sentaurus-TCAD software. The scalability of the novel DGHEMT is also studied by analysing the short channel effects. The attractive features of the proposed DGHEMT are intrinsic In0.80Ga0.20As/InAs/In0.80Ga0.20As channel, dual silicon delta doping sheets and platinum (Pt) buried gate technology. The proposed DGHEMT with Lg = 20 nm exhibits a gm_max of 3970 mS/mm and IDS_max of 1650 mA/mm at VGS = 0.6 V and VDS = 0.8 V. The proposed DGHEMT exhibits a threshold voltage of 20 mV which indicates its E-Mode behaviour. The sub-threshold swing (SS) and DIBL values obtained for Lg = 20 nm DGHEMT at VDS = 0.5 V are 74 mV/dec and 78 mV/V respectively. The Lg = 20 nm proposed E-Mode DGHEMT also exhibit a fT and fmax of 826 and 1615 GHz respectively at VDS = 0.6 V. The computed logic gate delay for the Lg = 20 nm DGHEMT is 31.25 fS with an electron velocity under the gate of 6.4 × 107 cm/S. This excellent RF and DC behaviour of the proposed DGHEMT makes them an excellent choice for future sub-millimetre wave and THz frequency applications.
关键词： quantum well (QW),InAs,Drain induced barrier lowering (DIBL),short channel effects (SCEs),gate delay,sub-threshold swing (SS)
更新于2025-09-23 15:23:52
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Numerical simulation on terahertz wave propagation in plasma channels
摘要： Terahertz (THz) wave generated by femtosecond laser ?lamentation can spatially constrained inside the plasma channels. Our simulation results show that this constraint to THz wave will gradually weaken with the increasing THz frequency. At the same time, results also indicate that the higher plasma density possesses the stronger constraint. In addition, the model ?eld radius and width of THz wave will become larger with the increasing plasma channel radius. Based on the simulation results we ?nd the changes of refractive index at THz wave play an important role on THz wave propagation in plasma channels.
关键词： Plasma channel,Waveguiding,Terahertz wave propagation
更新于2025-09-23 15:23:52
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Contactless parametric characterization of bandgap engineering in p-type FinFETs using spectral photon emission
摘要： In the last decade it has become increasingly popular to use germanium enriched silicon in modern field effect transistors (FET) due to the higher intrinsic mobility of both holes and electrons in SiGe as compared to Si. Whether used in the source/drain region (S/D) as compressive stressor, which is an efficient mobility booster on Si channel devices, or as channel material, the SiGe increases channel carrier mobility and thus enhancing device performance. Because the germanium content modifies the effective bandgap energy EG, this material characteristic is an important technology performance parameter. The bandgap energy can be determined in an LED-like operation of electronic devices, requiring forward biased p-n junctions. P-n junctions in FETs are source or drain to body diodes, usually grounded or reversely biased. This investigation applies a bias to the body that can trigger parasitic forward operation of the source/drain to body p-n junction in any FET. Spectral photon emission (SPE) is used here as a non-destructive method to characterize engineered bandgaps in operative transistor devices, while the device remains fully functional. Before applying the presented technique to a p-type FinFET device, it is put to the proof by verifying the nominal silicon bandgap on an (unstrained) 120 nm technology FET. Subsequently the characterization capability for bandgap engineering is then successfully demonstrated on a SiGe:C heterojunction bipolar transistor (HBT). In a final step, the bandgap energy EG of a 14/16 nm p-type FinFET was determined to be 0.84 eV, which corresponds to a Si0.7Ge0.3 mixture. The presented characterization technique is a contactless fault isolation method that allows for quantitative local investigation of engineered bandgaps in p-type FinFETs.
关键词： p-n junction,Heterojunction bipolar transistor,Bandgap characterization,p-channel FinFET,SiGe, strained Si,Body diode, parasitic operation,Bandgap engineering,Body bias voltage,HBT,Contactless fault isolation,Spectral photon emission,MOSFET
更新于2025-09-23 15:23:52
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Off-Grid Compressive Channel Estimation for mm-Wave Massive MIMO with Hybrid Precoding
摘要： To reduce the pilot overhead and improve the channel estimation accuracy in the massive MIMO system, various channel estimation algorithms employing the sparse signal reconstruction (SSR) scheme have been proposed. However, the spatial grid division leads to the trade-off between the estimation accuracy and the computational complexity. In addition, when the true angle is not on the discretized grid point which is referred as off-grid problem, the performance of SSR-based algorithms will degrade heavily. In this letter, a novel channel estimation algorithm which achieves superior performance under the off-grid scenario is proposed. At first, the conventional joint angle of arrivals/departures (AoAs/AoDs) estimation is transformed into two one-dimensional sub-problems. Then, the SSR-based framework is presented to obtain the initial sparse-support set. By minimizing the constructed objective function, the off-grid errors regarded as adjustable parameters are iteratively refined. In addition, scatter gains are acquired by LSE. Numerical simulations are provided to illustrate the superiority of the proposed algorithm in terms of estimation accuracy and computational complexity.
关键词： channel estimation,millimeter wave,massive MIMO,off-grid refinement,Compressive sensing
更新于2025-09-23 15:23:52
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Channel modeling and analysis of OWC-massive MIMO systems
摘要： In this paper, we study the difference between the uplink and downlink channels of short-range slant free-space optical wireless between Ground - alpine base stations using massive MIMO linear arrays at both ends. The uplink and downlink atmospheric loss, scintillation, beam spreading and pointing error model of linear array slant range are constructed. The uplink and downlink atmospheric loss, spatial coherence length, receiver beamwidth, pointing error variance, relative mean square error (RMSE) and bit error rate (BER) are compared and analyzed under different distances of different wavelengths of light waves. After simulation analysis, it is concluded that the uplink and downlink atmospheric losses are the same, the uplink receiver beamwidth is larger than the downlink, and the downlink coherence length and the pointing error variance are larger than the uplink, and both monotonously change with the wavelength of the light wave and the propagation distance.
关键词： Optical wireless communication,MSE,Wavelength,Channel modeling,Massive MIMO
更新于2025-09-23 15:23:52
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Adaptive resource allocation in FSO/RF multiuser system with proportional fairness for UAV application
摘要： The combination of free space optic(FSO) and unmanned aerial vehicle (UAV) can be a promising solution to last-mile problem because of FSO high bandwidth and flexibility of UAV. However, FSO is vulnerable to the atmospheric turbulence and transmitter configuration is limited on UAV. Therefore, in this paper, we investigate an adaptive resource allocation strategy to provide relative fair and high transmission capacity for users. In the proposed network model, the downlink scenario is considered and ground station communicates with UAV and its local users by FSO and RF links, respectively. According to the channel conditions and rate requirements from users, channel and power assignments should satisfy the capacity demand in reasonable. To this end, we decompose the original channel and power allocation problem with high computational complexity into low-complexity subproblems, corresponding to channel allocation in RF transmission phase and channel matching and power allocation in FSO transmission phase. Then, a heuristic efficient resource assignment algorithm is proposed to achieve the optimal capacity distribution for users. Numerical results show that the proposed method can asymptotically achieve optimal throughput. Furthermore, system throughput is higher at low transmitting power requirement than those of other existing methods.
关键词： UAV,proportional fairness,mixed FSO/RF,efficient resource allocation,channel capacity
更新于2025-09-23 15:23:52
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Compact Dual-Channel Balanced Filter and Balun Filter Based on Quad-Mode Dielectric Resonator
摘要： In this paper, we propose a method for designing a dual-channel balanced filter and a dual-channel balun filter based on the quad-mode dielectric resonator (DR) for the first time. By sharing one common quad-mode DR, two balanced filters or two balun filters are integrated as one single-cavity configuration, featuring compact size and high integration. A cylindrical DR with two short ends is investigated to construct the quad-mode DR. By properly arranging input and output feeding probes, two modes of the DR are only excited by the feeding probes of one channel and the other two modes are excited by that of the other channel. Accordingly, signals cannot be transmitted between the two channels, resulting in high isolation. Moreover, the required out-of-phase characteristics of the balanced and balun filters can be obtained by the inherent electromagnetic field properties of the DR without adding additional circuits, featuring a simple structure. For demonstration, a dual-channel balanced filter and a dual-channel balun filter are designed and fabricated, showing excellent balanced or balun filter performance of each channel as well as high isolation between the two channels. As compared to the other reported DR balanced and balun filters, the proposed designs exhibit a significant size reduction, which are attractive in wireless systems.
关键词： Balanced filter,high Q factor,dielectric resonator (DR),balun filter,MIMO,size reduction,dual-channel
更新于2025-09-23 15:23:52
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Precoding and Detection for Broadband Single Carrier Terahertz Massive MIMO Systems Using LSQR Algorithm
摘要： The terahertz (THz) communication utilizes the frequency spectrum above 300 GHz and is widely considered as a promising solution to the future high-speed short-range wireless communication beyond millimeter wave (mmWave) communication. While providing tens of gigahertz bandwidth, it is subjected to high propagation path loss, inter-symbol and inter-user interferences. The massive multiple-input-multiple-output (MIMO) can be applied to address these problems by cooperation between many access point (AP) antennas. However, the THz channel characteristics, including high propagation path loss, frequency selectivity and big number of samples per channel impulse response (CIR), require carefully tailored algorithm for massive MIMO signal processing. In this paper, we propose a single carrier minimum mean square error (MMSE) precoding and detection algorithm for frequency selective THz channels. The MIMO signal transmission is described with the block matrices. A gain control heuristic is introduced to reduce the complexity. The sparsity property of the channel is utilized to construct sparse channel matrices and the least square QR (LSQR) algorithm is applied to efficiently solve the problems. Besides the uniform antenna array, the hybrid array consisting of several subarrays is considered as well. Simulation results show that the massive MIMO array can provide a satisfactory performance in terms of bit error rate (BER).
关键词： detection,massive MIMO,frequency selective channel,precoding,LSQR algorithm,block matrix,minimum mean square error,THz communication
更新于2025-09-23 15:23:52