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Nonfullerene acceptors (NFAs) have attracted great attention in high-efficiency organic solar cells (OSCs). While the effect of molecular properties including structures and energetics on charge transfer has been extensively investigated, the effect of macroscopic-phase properties is yet to be revealed. Here we have performed a correlation study of the nanoscale-phase morphology on the photoexcited hole transfer (HT) process and photovoltaic performance by combining ultrafast spectroscopy with high temporal resolution and photo-induced force microscopy (PiFM) with high spatial and chemical resolution. In PM6/IT-4F, we observe biphasic HT behavior with a minor ultrafast (

Organic micropollutants have become serious threats to human health and the environment over the past years. Novel materials and technologies are urgently needed to remove environmental contaminants. Herein, spirobifluorene (SBF) and triptycene (TP) were crosslinked to produce four hierarchically porous organic polymers (NHCPs). The twisted spatial structures of the monomers endow the NHCPs with high surface areas and abundant pores, which make them suitable for removal of pollutants in aqueous solution through adsorption. According to the results from adsorption experiments, the NHCPs exhibited high removal efficiency and adsorption capacities for pollutants in solution. Particularly, NHCP-3 could remove 99.4% of bisphenol A (BPA) in a few seconds with a maximum adsorption capacity of 562 mg g−1. Furthermore, the NHCPs could be easily recovered by immersion in ethanol and recycled at least five times without a loss in efficiency.

The magnetic skyrmions have received a lot of attention because they have potential applications in spin torque nano-oscillators. In this paper, we numerically and analytically study the dynamics of edge skyrmions in circular nano-pillar oscillators with perpendicular magnetic anisotropy (PMA) free layer and spin polarizer. Numerical simulations demonstrate that a steady edge skyrmion oscillation mode with GHz frequency can be driven by spin currents and magnetic fields. The oscillation frequencies in circular nano-pillars with different radius are analytically derived, which agrees well with the numerical results. In addition, the steady oscillations of edge skyrmions are also observed in elliptical nano-pillars, in which the oscillation frequencies strongly depend on the eccentricity and perimeter of the elliptical nanopillar. It is found that the oscillation frequency of this edge skyrmion can range from 1 GHz to 6.7 GHz. The line width is about 55 MHz.

By introducing various N‐containing compounds as efficient linkers, a series of hyper‐crosslinked porous polymers with high surface areas and gas‐uptake values were synthesized by using the Friedel–Crafts alkylation reaction. Structural characterization indicated the presence of nitrogen atoms, and gas‐sorption experiments revealed that the high gas uptake benefitted from the high surface areas and the incorporation of N‐containing linkers as Lewis basic sites. Among these porous polymers, HCP‐4 had the highest H2 uptake of 9.29 mmol g−1 at 77 K and 0.1 MPa and the highest C2H2 uptake of 6.69 mmol g−1 at 273 K and 0.1 MPa, whereas HCP‐3 showed the best CO2 uptake of 4.42 mmol g−1 at 273 K and 0.1 MPa. To understand better the important role played by nitrogen in these polymers, the isosteric heat of adsorption and adsorption selectivity of CO2 over N2 were calculated. The results showed that the triazine‐based polymer HCP‐1 had the highest CO2 over N2 selectivity of 75.4 at 295 K and 0.1 MPa, which makes it the most potential candidate for CO2 capture.

In this study, a quaternary blending strategy was applied in the fabrication of organic photovoltaic devices and large-area modules. As a result, the ultimate quaternary organic solar cells (OSCs) deliver 16.71% efficiency for small-area devices and 13.25% for large-area ( 19.34 cm 2 ) modules (certified as 12.36%), which is one of the highest efficiencies for organic solar modules to date. Our results have proved the synergistic effects of multiple components in OSCs, providing an effective strategy for achieving high-performance organic photovoltaic devices and modules.

One-dimensional (1D) small-molecule semiconducting nanostructures (NSs) have attracted more and more attention due to their unique structures and photoelectric properties. However, the preparation of real ultrafine 1D organic nanocrystals (ONCs), in which the intermolecular charge transfer (CT) is confined to a 1D direction, is still a huge challenge. Here, we report a facile way to controllably synthesize uniform 1D ONCs of μ-oxo dimeric iron(III) porphyrin [(FeTPP)2O] in a cetyltrimethyl ammonium bromide (CTAB)-assisted wet chemical reaction (WCR). In this work, the shape evolution of the (FeTPP)2O NSs was shown by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). Interestingly, the regularity and aspect ratio of the (FeTPP)2O 1D NCs increased with time, while their diameters decreased. Further experiments proved that this was closely associated to the reconstruction of the CTAB micelles. After optimizing the experimental conditions, we not only synthesized uniform 1D ONCs with a width of ∼28 nm and/or an aspect ratio of ∼37, but also obtained 2D ONCs with a thickness of about 10 nm. Here, the finest 1D ONCs that we have seen to date have been prepared. The corresponding UV-vis absorption and photoluminescence (PL) spectra are enhanced with a decrease in the diameter and an increase in the aspect ratio of (FeTPP)2O 1D ONCs with high crystallinity, which clearly shows the first report of the confinement effect of the intermolecular CT state in 1D ONCs. This work paves a new route to prepare 1D ONCs and provides us with a chance to further understand and apply the intermolecular CT in 1D organic photoelectrical devices.

Massive multiple input multiple output (MIMO) is a promising technology that has been proposed to meet the requirement of the fifth generation wireless communications systems. For uplink massive MIMO systems, the typical linear detection such as minimum mean square error (MMSE) shows near-optimal performance. However, due to the direct matrix inverse, the computational complexity of the MMSE detection algorithm is too high, especially when there are a large number of users. Thus, in this paper, we propose an improved Gauss-Seidel algorithm by utilizing delayed over relaxation (DOR) scheme, which is named as delayed over relaxation Gauss-Seidel (DRGS) algorithm. The basic idea of the DOR scheme is to combine the predicted iterative step (n + 1) with the iteration of step (n − 1). The scheme can provide a significant improvement of the convergence speed for iterative algorithm. The theoretical analysis of DRGS algorithm shows that the proposed algorithm can reduce the computational complexity from O (K3) to O (K2), where K is the number of users. Simulation results verify that the DRGS algorithm can achieve almost the same BER performance as that of MMSE detection with a small number of iterations.

This paper proposed a robust spatial spectrum sensing algorithm to apply to a communication scenario which exist the estimated error of noise power and the jamming. A modified approximate model is proposed to include the estimated error of noise power and the jamming. The corresponding performance indicators are proposed. The proposed robust algorithm estimates the estimated error vector of noise power and the jamming vector, independently. The estimated error vector of noise power and the jamming vector are separated from model coefficient vector, and the influence of estimated error and jamming is mitigated. The robustness of proposed algorithm is achieved. Simulation results show that the proposed robust algorithm has best sensing performances, and best accuracy of PU estimation, comparing with other sparsity algorithms. The sensing performances of proposed robust algorithm are not easy to be affected by the sampling rate of secondary users. When the sampling rate of secondary users or SNR is increasing, these sensing performances of proposed robust algorithm are also increasing.

In this paper, a positioning system is designed based on the visible light communication (VLC) technology for the tracking of mobile target in the indoor environment. The practical received signal strength (RSS) can be measured for subsequent positioning algorithm by using the designed system. Based on the practical measurements, an empirical equation is proposed to estimate the target's distances relative to the referenced LEDs. Then, taking advantage of the relative distances, the location estimation can be obtained by the trilateration method. Furthermore, Kalman Filter is used for improving the positioning result computed by trilateration method. Finally, experimental results show that the average location errors by adopting the derived empirical formula and trilateration can reach to 3.4cm, and the accuracy of positioning can be promoted to 2.6cm by using Kalman Filter in a real wireless environment.

In this paper, a three-dimensional (3-D) positioning system using fingerprinting and K-Nearest neighbor is proposed. The implementation of the proposed positioning system based on visible light communication (VLC) is discussed. On-off keying (OOK) modulation, Manchester coding and time division multiplexing (TDM) are utilized to obtain both lossless data and accurate received signal strength indications (RSSIs) without sacrificing the comfort of indoor illumination. The proposed 3-D positioning algorithm is conducted in three processes. Firstly, we quickly traverse all sampling points in the fingerprint database to find the nearest neighbor and choose candidate sampling points around the nearest neighbor. Secondly, we conduct an iterative search among candidate sampling points to find K-Nearest neighbors. Finally, we obtain estimated coordinates using weighted average method. Experimental result shows that, the proposed system possesses fast location and high accuracy.

In this paper, we propose a novel noncoherent maximum likelihood detection (NMLD) method for differential spatial multiplexing (SM) multiple-input multiple-output (MIMO) systems. Unlike the conventional maximum likelihood detection (MLD) method which needs the knowledge of channel state information (CSI) at the receiver, WILD method has no need of CSI at either the transmitter or receiver. After repartitioning the observation block of multiple-symbol differential detection (MSDD) and following a decision feedback process, the decision metric of NMLD is derived by reforming that of MSDD. Since the maximum Doppler frequency and noise power are included in the derived decision metric, estimations of both maximum Doppler frequency and noise power are needed at the receiver for NMLD. A fast calculation algorithm (FCA) is applied to reduce the computational complexity of NMLD. The feasibility of the proposed WILD is demonstrated by computer simulations in both slow and fast fading environments. Simulation results show that the proposed NMLD has good bit error rate (BER) performance, approaching that of the conventional coherent MILD with the extension of reference symbols interval. It is also proved that the BER performance is not sensitive to the estimation errors in maximum Doppler frequency and noise power., Article, IEICE TRANSACTIONS ON COMMUNICATIONS. E93B(2):361-368 (2010)

Since the early 1970s, decision support systems (DSS) have evolved significantly. In this paper, the design and implementation of MSMiner, a developing platform for DSS, is introduced. The system is constructed on a data warehouse and integrated with a number of data mining algorithms. It is well suited for on-line analytical processing (OLAP). The characteristics of MSMiner include the ability to support multiple data sources and data mining strategies, additional organizational flexibility in regard to data and mining strategies, and the powerful expansibility of data mining tasks.

In this paper, multiple-symbol differential detection (MSDD) is applied to the differential single-carrier frequency-division multiple access (SC-FDMA) system. Both time domain and frequency domain MSDD are investigated to compensate for the performance loss of conventional differential detection comparing with coherent detection. The decision metric of time and frequency domain MSDD for SC-FDMA are derived respectively. Simulation results demonstrate the effectiveness of MSDD in some situations.

With the need of localization based services increasing, many algorithms are proposed using distance between two points and path loss exponent of the environment. In this paper, we propose an algorithm using received signal strength, Doppler Effect and frequency diversity in vehicular networks. The algorithm can estimate the path loss exponent and distance dynamically in mobile communication environment. And the higher the relative speed of vehicles, the better performance of the propose technique. We evaluate the performance of the proposed algorithm in the simulation and discuss the corresponding results.

In this paper, an adaptive blind equalization method is proposed for differential single-carrier frequency-division multiple access (SC-FDMA) system. Both time domain equalizer and frequency domain equalizer are investigated to combat the frequency selective fading. Simulation results show both the time domain and frequency domain equalization can improve the performance of differential SC-FDMA system in frequency selective fading channels.

With the rapid growth of the Internet, how to get information from this huge information space becomes an even more important problem. In this paper, An Intelligence Chinese Document Semantic Indexing System; ICDSIS, is proposed. Some new technologies are integrated in ICDSIS to obtain good performance. ICDSIS is composed of four key procedures. A parallel, distributed and configurable Spider is used for information gather; a multi-hierarchy document classification approach combining the information gain initially processes gathered web documents; a swarm intelligence based document clustering method is used for information organization; a concept-based retrieval interface is applied for user interactive retrieval. ICDSIS is an all-sided solution for information retrieval on the Internet.

In this paper, the differential encoding and detection methods in single-carrier frequency-division multiple access (SC-FDMA) systems are investigated. Like in OFDM systems, the differential encoding can be performed in time-domain or frequency-domain in SC-FDMA systems. Also, we can use differential encoding before or after the discrete Fourier transform (DFT) process. Thus the detail design of transmitter with each of the four differential coding methods and the corresponding detection methods is considered and analyzed.

In this paper, the differential unitary space-time-frequency coding (DUSTFC) scheme is applied in the single-carrier frequency-division multiple access (SC-FDMA) systems. The structure of transmitter and corresponding receiver is considered. The diversity gain of DUSTFC in SC-FDMA system are confirmed by simulation results in both time-domain and frequency-domain differential coding cases.

In this paper, a new indoor positioning algorithm is proposed for mobile objects based on track smoothing. Considering the effects of indoor environment and the individual anchor nodes, the algorithm is realized in two filtering phases to modify the UWB range measurements and the trilateration localization results by the Unscented Kalman Filter, which reduces the influence of the additive non-Gaussian noise. Furthermore, the filtered positioning results of a mobile object are smoothed by a proposed adaptive smoothing algorithm, and the accuracy has been significantly improved with the positioning RMSE less than 0.8m and the maximum error is about 1m.

A novel cooperative spectrum sensing approach is introduced based on a approximate model of the power spectral density (PSD) map in space and frequency domain. This scheme uses a model coefficients estimator based the theory of Variational Bayesian Inference. It reveals the unknown positions of transmitting CRs and the spectrum holes in authorized frequency bands, by capitalizing on the forms of sparsity in Cognitive Radio Networks.

We experimentally demonstrate a visible light communication (VLC) system using pulse amplitude modulation (PAM). A commercially available phosphorised white LED is used as the optical transmitter and a Si photodiode (PD) is used as the optical receiver. The experiment is mainly implemented in an indoor environment which is influenced by the sunlight and fluorescent lamp. In variant conditions, the experimental results using 4-PAM and 2-PAM (i.e. on-off-keying (OOK)) and the related analysis are reported.

The research of localization has become a more and more important topic with the popularity of ubiquitous mobile computing. In indoor environment, since the global positioning system (GPS) is disabled, many miniaturized wireless and sensing technologies have shown giant potential in positioning applications such as Inertial Navigation. In this context, this paper present a methodology to locate and track pedestrians accurately in indoor scenarios, the proposed method employs the extended Kalman filter (EKF) to integration Received Signal Strength Indication (RSSI) measurements with the Inertial Navigation technology. Aiming at the cumulative errors existed in Pedestrian Dead Reckoning (PDR) algorithm, this method uses RSSI information as measurement vector of EKF to correct the cumulative errors. Experimental results show that the proposed fusion method can present more reliable positioning estimations.

In this paper, voice transmission is considered in visible light communication (VLC) systems. A digital voice transmission system is designed and analyzed for better quality and capacity than conventional analog voice transmission system. Commercially available white LED is used as the light source in this system, and to fit for the property of it, multi-level pulse code modulation (MPCM) is chosen as the VLC modulation method. A set of system prototype is developed by mainly using the field-programmable gate array (FPGA). Testing results of the prototype show that the system is reasonable and stable.

In this paper, to improve the data transmission rate, visible light communication (VLC) system based on multi-level pulse code modulation (MPCM) is considered. This system uses different brightness level of the visible light signals to realize the multi-level modulation, thus a high data transmission rate, which is several times of that in 2-level modulation system, can be achieved. The overall design of the system is firstly considered. Then with 4-level modulation as an example, a set of system prototype is developed. Testing results of the prototype show that the system is reasonable and stable. Therefore, it is proved that applying the MPCM in VLC system is feasible and effective.

In this paper, an intercarrier interference (ICI) suppression method for frequency domain differential orthogonal frequency division multiplexing (OFDM) systems with multiple symbol differential detection (MSDD) in time-varying frequency-selective fading channels is proposed. The decision metric is derived by considering the statistical effects of ICI from all the subcarriers as well as considering the fading autocorrelations. Knowledges of transmitted signals from both inner and outer subcarriers of an MSDD observation interval can be used to estimate and mitigate the effects of ICI. The effectiveness of the proposed method is demonstrated by computer simulations.

In this paper, multiple-symbol differential detection (MSDD) for space-time block codes (STBC) is considered over fast Rayleigh fading multiple-input multiple-output (MIMO) channels. The decision metric is derived by considering the fading autocorrelation, and the M-algorithm is adopted to reduce the computational complexity of the decision metric. Simulation results demonstrate that MSDD is effective to fill the performance gap between conventional differential detection and coherent detection of differential STBC by extending the observation interval.

In this paper, the diversity reception of differential space-time block coding (STBC) system using multiple-symbol differential detection (MSDD) method with multiple receive antennas is considered. Postdetection maximum ratio combining (MRC), postdetection equal-gain combining (EGC) and predetection selective combining (SC) are used as diversity combining techniques. Their performance is analyzed by computer simulations

How to get text information from this huge information space becomes a more important problem with the rapid growth of the Internet. A semantic indexing system GHUNT based on concept space is proposed to solve the problem. Some new technologies are integrated in GHUNT to obtain good performance. GHUNT is an all-sided solution for information retrieval on the Internet.