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A revised modulated free carrier absorption (MFCA) theory is proposed, in which photomodulated thermal reflectance (PMTR) is subtracted from the transmitted signals of semiconductors. With this theory, one simultaneously extracts the carrier transport properties, such as the carrier lifetime, carrier diffusion coefficient, and the front surface recombination velocity, of silicon wafers. Proof-of-concept experiments were performed on a single crystal p-type, 100 cut silicon having $$8\,\Omega {\cdot }\hbox {cm}$$ to $$12\,\Omega {\cdot }\hbox {cm}$$ resistivity. MFCA and transmitted data (composed of MFCA and PMTR) are fitted to an MFCA theoretical model. Fitted results showed that the accuracies of fitted transport properties can be greatly improved by the MFCA technique if the PMTR component is subtracted from the transmitted signal. [ABSTRACT FROM AUTHOR]

The photothermal radiometry (PTR) technique is an effective non-destructive testing technique for detecting defects in materials. In this paper, a piece of commercial amorphous silicon (a-Si) thin-film solar cells with some artificial mechanical defects has been investigated by the transmission PTR imaging system. Firstly, a simplified analytical expression of a normalized transmission PTR signal was employed to characterize defects. Secondly, the corresponding experimental system has been set-up for obtaining several thermal images of the sample. Thirdly, different kinds of defects have been analyzed and identified by the thermal images. The results show that not only the artificial mechanical defects on the sample can be detected, but also some defects occurring in the manufacturing process can be detected by the transmission PTR imaging system. [ABSTRACT FROM AUTHOR]

Transdermal drug delivery (TDD) implemented by especially low-frequency ultrasound is generally known as sonophoresis or phonophoresis which has drawn considerable wide attention. However, TDD has not yet achieved its full potential as an alternative to conventional drug delivery methods due to its bulky instruments. In this paper, a cymbal-type piezoelectric composite transducer (CPCT) which has advantages over a traditional ultrasound generator in weight, flexibility, and power consumption, is used as a substitute ultrasonicator to realize TDD. First, theoretical research on a CPCT based on the finite element analysis was carried out according to which a series of applicable CPCTs with bandwidths of 20 kHz to 100 kHz were elaborated. Second, a TDD experimental setup was built with previously fabricated CPCTs aimed at the administration of glucose. Finally, the TDD performance of glucose molecule transport in porcine skin was measured in vitro by quantifying the concentration of glucose, and the time variation curves were subsequently obtained. During the experiment, the driving wave form, frequency, and power consumption of the transducers were selected as the main elements which determined the efficacy of glucose delivery. The results indicate that the effectiveness of the CPCT-based delivery is constrained more by the frequency and intensity of ultrasound rather than the driving waveform. The light-weight, flexibility, and low-power consumption of a CPCT can potentially achieve effective TDD. [ABSTRACT FROM AUTHOR]

Temporal segmentation of human motion data is an essential preparation process for action recognition. Due to the variability in the temporal scale of human action and the complexity of representing articulated motion, the research of it encounters many difficulties. Especially, when the number of behaviors contained in the motion sequences is unknown in advance, traditional algorithms cannot segment sequences successfully. In this paper, we extend previous works on change-points detection by probabilistic principle component analysis (PPCA). Based on it, an algorithm which is an extension of PCA and Maximum Mean Discrepancy between samples is proposed for estimating the cluster number. Finally, we optimize our approach and detect cyclic units of each action by aligned cluster analysis. We evaluate and compare the approach with the state-of-the-art methods on Synthetic data, Motion Capture Dataset and Kinect data. Experimental results demonstrate the effectiveness of our approach. [ABSTRACT FROM AUTHOR]

A cymbal piezoelectric composite transducer (CPCT) has been developed in recent years, which converts small radial deformation into larger longitudinal deformation. In this paper, the finite element analysis (FEA) method is used to analyze the characters of CPCT, by which the optimized CPCT has been made. Firstly, the FEA theory of a CPCT has been described, and the two-dimensional FEA model of a CPCT has been established by ANSYS. Secondly, the simulation and analysis about the relationships between structural parameters and displacement have been carried out, by which the CPCT samples have been made with optimized structure parameters. Thirdly, using laser interferometry, voltage-displacement relationships of CPCT samples have been measured. Finally, the displacement hysteresis and the aging behavior of a CPCT have been analyzed. [ABSTRACT FROM AUTHOR]

The photoacoustic piezoelectric (PAPE) technique is an effective non-destructive testing technique for detecting defects in materials. In this paper, Chinese national standard railway cracks have been detected by thermal wave imaging based on the PAPE technique. First, the theory of the PAPE technique has been introduced and the corresponding imaging principle has been analyzed. Second, the corresponding experimental system has been setup, and the imaging tests have been carried out. Third, two kinds of standard cracks have been examined by the imaging system. The results show that thermal wave imaging based on the PAPE technique can effectively image and identify the cracks at different depths, which lays a foundation for practical application to the detection of rail cracks. [ABSTRACT FROM AUTHOR]

In this paper, a new multiple signal classification (MUSIC)-based source localization algorithm is proposed to localize a hybrid of near-field (NF) and far-field (FF) sources. The MUSIC estimator for localizing the FF sources is referred to as the FF-MUSIC estimator. On the other hand, the NF-MUSIC estimator is designed for localizing the NF sources as well. In between the processing of these two estimators, the Capon spatial spectrum is exploited to reconstruct a pure NF covariance matrix. The proposed algorithm requires only several one-dimensional (1-D) spectral searches and does not involve any computations of high-dimensional iterative optimization, higher-order cumulants, and parameter pairing. Unlike the existing algorithms, which are derived based on the second-order Taylor series approximation, i.e., Fresnel approximation, of the spatial phase factor, the proposed algorithm is applicable to any-order expansion of the spatial phase factor. Moreover, it works well for non-uniform arrays, whereas the existing algorithms can only be applied to uniform arrays. [ABSTRACT FROM AUTHOR]

The conventional photoacoustic piezoelectric (PAPE) model did not take into account the influence of the piezoelectric transducer (PZT) on the vibrations of the sample, and this approximation brought certain error. In this article, a simple method has been proposed to investigate the vibrations of the sample-PZT combination, and the theory of the PAPE technique has been modified. By introducing an equivalent thickness parameter, the two-layered model has been simplified and an analytical expression for the phase of the PAPE output signal has been obtained. The experimental system has been set up, and the thermal diffusivities of several metal samples have been measured. The experimental results show that the modified model has a higher accuracy than the conventional model. [ABSTRACT FROM AUTHOR]

The history for the development of chiral phosphorus ligands in catalytic asymmetric hydrogenation is briefly highlighted. This review focuses on the recent advances in the synthesis of the monodentate phosphorus ligands and their applications in catalytic asymmetric hydrogenation. The examples highlighted in this article clearly demonstrated the importance and advantages of monodentate phosphorus ligands, which had been ignored for 30 a and experienced a renaissance at the very beginning of this millennium, particularly in the area of asymmetric hydrogenation. [ABSTRACT FROM AUTHOR]

Many existing near-field source localization algorithms assume simplified models, for example, the Fresnel approximation model. Unlike these works, a new algorithm is herein proposed to localize multiple near-field electromagnetic sources under the exact source-array propagation model. Using the data measured by a linear (not necessarily uniform) cocentered orthogonal loop and dipole (COLD) array, three cumulant matrices are firstly defined to construct two matrix pencils. The magnitudes of the two matrix pencils' generalized eigenvalues are then combined with their phases to extract the direction-of-arrival (DOA) and range estimates of the sources. The key idea of the new algorithm is to use a set of coarse estimates obtained from the magnitudes to resolve the set of ambiguous estimates obtained from the phases. In addition, the proposed algorithm estimates the polarizations without needing the prior estimation of the DOA-range parameters. This proposed algorithm is analytic, requires no iterative computations, and does not need to confine the inter-element spacing to be within a quarter wavelength. [ABSTRACT FROM AUTHOR]

Many mixed near-field (NF) and far-field (FF) source localization algorithms in the open literature are developed based on the Fresnel approximation model, which is a simplified model of the exact source-array spatial geometry. Unlike these algorithms, in this paper, a new algorithm is derived to localize a mixture of NF and FF electromagnetic sources based on the exact spatial model with the use of a linear cocentered orthogonal loop and dipole (COLD) array. The summation of the dipole covariance matrix and the loop covariance matrix is shown to be independent of the source polarization parameters. Using this property, a multiple signal classification (MUSIC) pseudo-spectrum is defined for joint angle and range estimation. To facilitate the computational efficiency of the algorithm, a set of coarse angle and range estimates are derived using the estimating signal parameter via rotational invariance techniques (ESPRIT) philosophy to initiate the MUSIC searching. The major advantage of the proposed algorithm over the existing algorithms is that it does not introduce the systematic errors caused by the mismatch between the exact model and the Fresnel approximation model. [ABSTRACT FROM AUTHOR]

• Fe-Mn bimetallic phosphorus trisulfide heterostructure was firstly synthesized. • The frame structure of FeMnP 2 S 6 is conducive to holding and trapping the sulfur. • The strong electrical coupling on Fe 2 P 2 S 6 surface enhances kinetics. • D-band center shifts to Fermi level via introducing Mn 2 P 2 S 6 , promoting catalysis. Monofunctional host materials of lithium-sulfur (Li-S) batteries are inadequate to simultaneously address the complex issues including "shuttle effect" and sluggish redox kinetics. Herein, iron and manganese bimetallic phosphorus trisulfide (Fe-MnP 2 S 6) with heterointerfaces and a semi-open frame structure was synthesized as a multifunctional host material for Li-S batteries. Theoretical calculations suggest that due to the strong electronic coupling effect, electrons migrate from the MnPS 3 layer to the FePS 3 layer, accelerating charge and ion transfer on the surface of FePS 3. The d-band center of metal atoms shifts towards the Fermi level through the introduction of Mn 2 P 2 S 6 , enhancing the interaction with polysulfides. Moreover, the frame exhibits excellent structural stability and physical limiting ability of sulfur. As a result, the cell with Fe-MnP 2 S 6 delivers impressive electrochemical performance and redox kinetics, including a capacity of 1388 mAh/g at 0.2C, a rate performance of 850 mAh/g at 4C and a capacity attenuation rate of 0.028 % per cycle over 1,000 cycles at 1C. Through meticulous structural design and optimal composition adjustments, our work explores the mechanism of metal phosphorus trisulfides (MPS 3) in Li-S batteries. [ABSTRACT FROM AUTHOR]

A novel Bacillus licheniformis strain (DM-1) was isolated from a mature reservoir in Dagang oilfield of China. DM-1 showed unique properties to utilize petroleum hydrocarbons and agroindustrial by-product (molasses) for exopolysaccharide (EPS) production under oil recovery conditions. The DM-1 EPS was proven to be a proteoglycan with a molecular weight of 568 kDa. The EPS showed shear thinning properties and had high viscosities at dilute concentrations (<1%, w/v), high salinities, and elevated temperatures. Strain DM-1 could degrade long-chain n-alkanes up to C36. Viscosity reduction test have shown that the viscosity of the crude oil was reduced by 40% compared with that before DM-1 treatment. Sand pack flooding test results under simulated reservoir conditions have shown that the enhanced oil recovery efficiency was 19.2% after 7 days of in-situ bioaugmentation with B. licheniformis DM-1. The obtained results indicate that strain DM-1 is a promising candidate for in situ microbial enhanced oil recovery (MEOR). [ABSTRACT FROM AUTHOR]

Simulations are performed to investigate the uniqueness of simultaneous determination of electronic transport properties (the carrier lifetime, the carrier diffusivity, and the front surface recombination velocity) of silicon wafers by laterally resolved modulated free carrier absorption (MFCA) and multiparameter fitting. The dependences of MFCA amplitude and phase on these transport properties at different pump-probe-beam separations and modulation frequencies are analyzed. The uncertainties of the fitted parameter values are analyzed by investigating the dependences of a mean square variance including both the amplitude error and phase error on corresponding electronic transport parameters. Simulation results show that the electronic transport parameters can be determined accurately through fitting experimental MFCA data carrying both frequency- and space-domain information of carrier diffusion to a rigorous MFCA model. Among the three transport parameters, the carrier diffusivity can be determined most precisely, with an uncertainty of less than ±5%, due to the highest sensitivity of the laterally resolved MFCA signal to the diffusivity. The highly accurate determination of the diffusivity further improves the precision of the carrier lifetime and the front surface recombination velocity values simultaneously determined via multiparameter fitting. Experiments were performed with a silicon wafer and the results were in good agreement with the theoretical simulations. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. The early diagnosis of HCC is greatly helpful to achieve long-term disease-free survival. However, HCC is usually difficult to be diagnosed at an early stage. The aim of this study was to create the prediction model to diagnose HCC based on gene expression programming (GEP). GEP is an evolutionary algorithm and a domain-independent problem-solving technique. Clinical data show that six serum biomarkers, including gamma-glutamyl transferase, C-reaction protein, carcinoembryonic antigen, alpha-fetoprotein, carbohydrate antigen 153, and carbohydrate antigen 199, are related to HCC characteristics. In this study, the prediction of HCC was made based on these six biomarkers (195 HCC patients and 215 non-HCC controls) by setting up optimal joint models with GEP. The GEP model discriminated 353 out of 410 subjects, representing a determination coefficient of 86.28% (283/328) and 85.37% (70/82) for training and test sets, respectively. Compared to the results from the support vector machine, the artificial neural network, and the multilayer perceptron, GEP showed a better outcome. The results suggested that GEP modeling was a promising and excellent tool in diagnosis of hepatocellular carcinoma, and it could be widely used in HCC auxiliary diagnosis. Graphical abstract The process to establish an efficient model for auxiliary diagnosis of hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

In this work, we irradiated a high-definition (HD) industrial camera based on a commercial-off-the-shelf (COTS) CMOS image sensor (CIS) with Cobalt-60 gamma-rays. All components of the camera under test were fabricated without radiation hardening, except for the lens. The irradiation experiments of the HD camera under biased conditions were carried out at 1.0, 10.0, 20.0, 50.0 and 100.0 Gy/h. During the experiment, we found that the tested camera showed a remarkable degradation after irradiation and differed in the dose rates. With the increase of dose rate, the same target images become brighter. Under the same dose rate, the radiation effect in bright area is lower than that in dark area. Under different dose rates, the higher the dose rate is, the worse the radiation effect will be in both bright and dark areas. And the standard deviations of bright and dark areas become greater. Furthermore, through the progressive degradation analysis of the captured image, experimental results demonstrate that the attenuation of signal to noise ratio (SNR) versus radiation time is not obvious at the same dose rate, and the degradation is more and more serious with increasing dose rate. Additionally, the decrease rate of SNR at 20.0, 50.0 and 100.0 Gy/h is far greater than that at 1.0 and 10.0 Gy/h. Even so, we confirm that the HD industrial camera is still working at 10.0 Gy/h during the 8 h of measurements, with a moderate decrease of the SNR (5 dB). The work is valuable and can provide suggestion for camera users in the radiation field. [ABSTRACT FROM AUTHOR]

A nonlinear photocarrier radiometry (PCR) based quantitative defect characterization method is applied to determine the electronic transport parameters of the implantation layer of B+ ion-implanted silicon wafers with different implantation doses. A rigorous two-layer nonlinear PCR model is employed to fit the experimental modulation frequency dependences of PCR amplitude and phase to determine the transport parameters, that is, the carrier lifetime, carrier diffusion coefficient, and front surface recombination velocity of the implantation layer via multiparameter fitting. In the multiparameter fitting, the effects of the implantation layer thickness determination on the extraction of the electronic transport properties of the implantation layer are discussed via setting the thickness as a free parameter in the multiparameter fitting and fixed parameters determined by Monte Carlo based TRIM calculation. The fitted implantation layer thicknesses are in good agreement with that determined via TRIM calculation with a modified electronic damage threshold. Monotonic dependences of the transport properties of the implantation layers on the implantation dose are observed, and the effects of impurity density on the transport properties of the implantation layers are discussed. Good agreements between the experimental implantation dose dependence of the nonlinearity coefficient and corresponding theoretical calculations with the determined transport parameters are obtained. These results show that the two-layer nonlinear PCR model is accurate for quantitatively characterizing the transport properties and thickness of the ion-implantation layers of silicon wafers, and the nonlinear PCR technique is appropriate for precise defect characterization in the semiconductor manufacturing processes. [ABSTRACT FROM AUTHOR]

The thermal diffusivity of reduced activation ferritic/martensitic steel (CLF-1), which is recognized as the primary candidate structural material for the test blanket module of the international thermal-nuclear experimental reactor, has been studied by the time-domain (TD) photoacoustic piezoelectric (PAPE) technique. The TD PAPE model based on a simplified thermoelastic theory under square-wave modulated laser excitation is presented, relating the TD PAPE signal to the modulation frequency, thermal diffusivity, and other material parameters. Thermal diffusivities of reference samples such as copper and nickel were measured and analyzed, by which the validity of the technique is verified. The thermal diffusivity of the CLF-1 sample was measured to be $$8.2\,\text {mm}^{2}{\cdot }\text {s}^{-1}$$ , which is at a medium level among the ordinary steel materials ( $$3\,\text {mm}^{2}{\cdot }\text {s}^{-1}$$ to $$14\,\text {mm}^{2}{\cdot }\text {s}^{-1})$$ and has decent heat-dissipation ability. The results show that the TD PAPE technique can provide a fast and economic way for the investigation of the thermophysical properties of fusion reactor structural materials. [ABSTRACT FROM AUTHOR]

Photoacoustic spectroscopy (PAS), the non-destructive method to detect residue of dimethyl-dichloro-vinyl-phosphate (DDVP) pesticide in a cuticle of apple, is described. After constructing the PA experimental setup and identifying three characteristic peaks of DDVP in the near ultraviolet region, the PA spectra of an apple cuticle contaminated with DDVP were collected. The artificial neural network method was then applied to analyze data quantitatively. The results show a correlation coefficient exceeding 0.99 and a detection limit of 0.2 ppm, which is within the national food safety standard for maximum residue limits for pesticides in food (GB 2763-2012). This fact and the non-destructive character of PAS make the approach promising for detection of pesticide residue in fruits. [ABSTRACT FROM AUTHOR]

Thermal-physical property is one of the most important properties of materials. The conventional frequency-domain photoacoustic piezoelectric (PAPE) technique has been developed as an important method for thermal diffusivity determination. In this paper, the PAPE technique is extended to time domain (TD). First, based on a simplified thermoelastic model, the TD PAPE theory under square-wave-modulated excitation was developed, the dependence of the TD PAPE signal on modulation frequency as well as material parameters was obtained, and the determination of thermal diffusivity was simulated and theoretically analyzed. Second, the experimental system and the corresponding measurement method were established. Third, thermal diffusivities of various standard samples, such as copper, aluminum, and nickel, were measured, and the effectiveness of the technique was verified. The results show that the TD PAPE technique can provide a simple, fast and effective way for thermal diffusion study. [ABSTRACT FROM AUTHOR]

Spectral matting is the state-of-the-art matting method and can well solve the highly under-conditioned matte problem without manual intervention. However, it suffers from huge computation cost and inaccurate alpha matte. This paper presents a modified spectral matting method which combines saliency detection algorithm to get a higher accuracy of alpha matte with less computational cost. First, the saliency detection algorithm is used to detect general locations of foreground objects. For saliency detection method, original two-stage scheme is replaced by feedback scheme to get a more suitable saliency map for unsupervised image matting. Next, matting components are obtained through a linear transformation of the smallest eigenvectors of the matting Laplacian matrix. Then, the improved saliency map is used for grouping matting components. Finally, the alpha matte is obtained based on matte cost function. Experiments show that the proposed method outperforms the state-of-the-art methods based on spectral matting both in speed and alpha matte accuracy. [ABSTRACT FROM AUTHOR]

Using the modified photoacoustic piezoelectric (PAPE) technique, the influence of the piezoelectric transducer on the vibrations of the sample is taken into account. The modified PAPE technique is employed to determine the average thermal diffusivities of the porcine tissues, which include fresh and dry skin, fat, and muscle. The values of the thermal diffusivities of all measured porcine tissues determined by the modified PAPE technique are smaller than those of the conventional ones, especially for the dry skin and fresh fat samples. The thermal diffusivity of the fresh skin sample is the biggest, and the dry samples of different tissues have similar thermal properties with each other. These results show that the modified PAPE technique can provide thermal characterization of the porcine tissues more effectively. [ABSTRACT FROM AUTHOR]

Abstract: Reduced Activation Ferritic/Martensitic (RAFM) steel has been chosen as structural material for China Helium-Cooled Ceramic Breeder Test Blanket Module (CN HCCB-TBM). The magnetization of RAFM definitely increases the toroidal field perturbation (called TF ripple) in international thermonuclear experimental reactor (ITER). The TF ripple could cause ripple loss of high-energy particles and result in a large localized heat load on the first wall of TBMs. Thus some positive measures to reduce the TF ripple generated by TBMs have been evaluated by finite element models (FEM) in this paper. It has been shown that under the intervention of ferromagnetic inserts (FIs) the TF ripple could be reduced to the acceptable level of ITER (namely, TF ripple ∼0.7% at R =8.2m of plasma edge near the equatorial plane) while fully considering several actual combinations (mass-reduction and recess) of HCCB-TBM and introduction of correction coils. [Copyright &y& Elsevier]

Abstract: The general design of China Helium-Cooled Solid Breeder Test Blanket Module (CN HCSBTBM) needs to withstand the related electromagnetic loads such as mechanical force and torques during plasma transients in ITER. The preliminary electromagnetic safety analyses for the electromagnetic loads during two plasma disruption scenarios have been performed with ANSYS Finite Element Module (FEM) code. At the same time the ways to reduce the perturbation of the toroidal field (TF) ripple have been valuated by taking fully account of the TBM and the ferromagnetic inserts. The maximum Tresca stress occurs at exponential decay of plasma current and its value is 33.2MPa, which is within the allowable limits. The TF ripple will be effectively reduced to a desirable scope with the integrated considerations of the design and look for balance among the ferromagnetic inserts, the TBM and ITER frame. [ABSTRACT FROM AUTHOR]

Our aim was to investigate the effect of artificial liver blood purification treatment on the survival of severe/critical patients with coronavirus disease 2019 (COVID‐19). A total of 101 severe and critical patients with coronavirus SARS‐CoV‐2 infection were enrolled in this open, case‐control, multicenter, prospective study. According to the patients' and their families' willingness, they were divided into two groups. One was named the treatment group, in which the patients received artificial liver therapy plus comprehensive treatment (n = 50), while the other was named the control group, in which the patients received only comprehensive treatment (n = 51). Clinical data and laboratory examinations, as well as the 28‐day mortality rate, were collected and analyzed. Baseline data comparisons on average age, sex, pre‐treatment morbidity, initial symptoms, vital signs, pneumonia severity index score, blood routine examination and biochemistry indices etc. showed no difference between the two groups. Cytokine storm was detected, with a significant increase of serum interleukin‐6 (IL‐6) level. The serum IL‐6 level decreased from 119.94 to 20.49 pg/mL in the treatment group and increased from 40.42 to 50.81 pg/mL in the control group (P <.05), indicating that artificial liver therapy significantly decreased serum IL‐6. The median duration of viral nucleic acid persistence was 19 days in the treatment group (ranging from 6 to 67 days) and 17 days in the control group (ranging from 3 to 68 days), no significant difference was observed (P =.36). As of 28‐day follow‐up,17 patients in the treatment group experienced a median weaning time of 24 days, while 11 patients in the control group experienced a median weaning time of 35 days, with no significant difference between the two groups (P =.33). The 28‐day mortality rates were 16% (8/50) in the treatment group and 50.98% (26/51) in the control group, with a significant difference (z = 3.70, P <.001). Cytokine storm is a key factor in the intensification of COVID‐19 pneumonia. The artificial liver therapy blocks the cytokine storm by clearing inflammatory mediators, thus preventing severe cases from progressing to critically ill stages and markedly reducing short‐term mortality. [ABSTRACT FROM AUTHOR]

Thermal diffusivity was confirmed to be a useful parameter for evaluating the aging degree of silicone rubber composite insulators widely used in high-voltage–power systems. However, the aging induced thermal diffusivity change of composite insulators not only is related to the initial thermal diffusivity of fresh silicone rubber, but also could be within a certain range for fresh composite insulators due to composition differences of base polymer and fillers and additives, makes the direct correlation of thermal diffusivity of aged composite insulator to aging degree difficult. In this work, thermal diffusivities of fresh composite insulators with different voltage grades, different mechanical load grades, and manufactured by different vendors are determined with photothermal radiometry (PTR) by fitting experimental frequency dependences of PTR amplitude and phase to an appropriate theoretical model. The thermal diffusivities of composite insulators from two vendors are approximately 3.70 × 10−7 m2·s−1 to 3.76 × 10−7 m2·s−1 and 4.87 × 10−7 m2·s−1 to 4.94 × 10−7 m2·s−1, respectively, showing significant difference, due to composition difference. The thermal diffusivities of composite insulators with voltage grades 35 kV, 110 kV, and 220 kV, and with mechanical load grades 70 KN, 100 KN, and 120 KN are also measured and found to be only slightly divergent, due to the same composition. In addition, the thermal diffusivity uncertainties of two vendors are quite different, indicating sample homogeneity discrepancy. This variation is useful information for evaluating aging process of silicone rubber composite insulators from the thermal diffusivity measurements of aged composite insulators. [ABSTRACT FROM AUTHOR]

Two-layer linear and nonlinear models were employed to investigate the influence of the nonlinear dependence of photocarrier radiometry (PCR) signal on excitation power for ion-implanted silicon wafers on the determination of carrier transport parameters of ion-implanted layers in the frequency domain. Three silicon wafers were measured at 830 nm excitation wavelength, with the ion-implantation dose of 1011, 1013, and 1016 cm−2, respectively. The effect of nonlinear coefficient on the multi-parameter fitting for electronic transport parameter determination was analyzed via theoretical simulations and experimental measurements. Both simulation and experimental results showed that the multi-parameter fitted results obtained via the linear PCR model (ignoring the nonlinearity) were significantly different from that obtained via the nonlinear PCR model (taking into account the nonlinearity). With the linear PCR model, the fitting errors in the determination of transport parameters of ion-implanted layers were highly sensitive to the nonlinearity coefficient. For low-implantation-dose silicon wafers with high nonlinearity coefficients close to 2, the square variance increased drastically, and the fitting errors were non-acceptably high. Comparison of the electronic transport parameters determined via the two-layer linear and nonlinear PCR models clearly showed that two-layer nonlinear PCR model is much more suitable than the linear model for describing the PCR signals and is more accurately for characterizing the carrier transport parameters of ion-implanted silicon wafers. [ABSTRACT FROM AUTHOR]

A nonlinear two-layer model was developed to describe and analyze Photocarrier Radiometric (PCR) signals of ion-implanted Si wafers which are intrinsically nonlinear with excitation laser power. The thickness of the implantation layer and the optical/electronic damage threshold for different implantation doses were estimated using the Monte Carlo method and the effective medium approximation theory, respectively, which can provide key parameter values for the model to calculate the nonlinearity coefficient, defined as the slope of PCR amplitude versus excitation power in log-log scale. Experimentally, the nonlinearity coefficients of seven c-Si wafers with implantation doses from 1011 to 1016 cm-2 were measured at two different excitation wavelengths (830 and 405 nm), and good agreement between theory and experiment was found. Results show that the nonlinearity coefficient has a negative correlation with the implantation dose, and the coefficient measured at 405 nm is consistently smaller than that measured at 830 nm for each sample. Compared with the conventional PCR models, the nonlinear two-layer model proposed here is more coincident with experimental facts, thus enabling PCR to provide more accurate quantitative characterization of the carrier recombination and transport properties of ion-implanted semiconductor wafers. [ABSTRACT FROM AUTHOR]

Abstract: Photodetectors, which can convert light signals into electrical signals, are important opto‐electronic devices in imaging, optical communication, biomedical/biological sensing, and so on. Here a solution‐processed photodetector based on the triple cation perovskite is demonstrated. The perovskite photodetectors show a high detectivity, high speed, as well as excellent environmental stability. Operating at a low voltage bias of 2 V, the photodetectors exhibit a large on/off ratio of 105, high specific detectivity of ≈1013 Jones, and a fast photoresponse with 3 dB bandwidth up to 0.82 MHz. Further analysis demonstrates that such performance originates from the modulated Schottky barrier height by illumination. The barrier suppresses dark current without any illumination, but it can be effectively lowered under illumination, thus resulting in a more efficient charge extraction and collection. The results demonstrate a great potential of triple cation perovskite in photodetection and provide a route to achieve high performance devices. [ABSTRACT FROM AUTHOR]

Human action recognition is very important and significant research work in numerous fields of science, for example, human-computer interaction, computer vision and crime analysis. In recent years, relative geometry features have been widely applied to the description of relative relation of body motion. It brings many benefits to action recognition such as clear description, abundant features etc. But the obvious disadvantage is that the extracted features severely rely on the local coordinate system. It is difficult to find a bijection between relative geometry and skeleton motion. To overcome this problem, many previous methods use relative rotation and translation between all skeleton pairs to increase robustness. In this paper we present a new motion representation method. It establishes a motion model based on the relative geometry with the aid of special orthogonal group SO(3). At the same time, we proved that this motion representation method can establish a bijection between relative geometry and motion of skeleton pairs. After the motion representation method in this paper is used, the computation cost of action recognition reduces from the two-way relative motion (motion from A to B and B to A) to one-way relative motion (motion from A to B or B to A) between any skeleton pair, namely, permutation problem is simplified into combinatorics problem . Finally, the experimental results of the three motion datasets are all superior to present skeleton-based action recognition methods. [ABSTRACT FROM AUTHOR]

A novel interface material 3-Thiopheneboronic acid (TBA) is first utilized as a multi-functional layer for PSCs application, which achieves the collaborative optimization of 1) energy level arrangement, 2) interface defect passivation and 3) perovskite crystallization. Consequently, the efficiency of TBA-based device increase from 19.74% to 21.80%, with an excellent stability. [Display omitted] • 3-Thiopheneboronic acid (TBA) is used as multifunctional interface material. • A synergy of energy level matching, defect passivation and better crystallization. • TBA-treated PSCs show an improvement in efficiency from 19.74% to 21.80%. • The ambient stability of PSCs is consequently enhanced by using TBA. Drawbacks like serious interface defects, imperfect energy level arrangement and uncontrollable perovskite nucleation hinder further improvement to achieve efficient and stable planar perovskite sollar cells (PSCs), which fortunately can be solved by interface modification with small molecules. However, it is still a challenge to develop more simple and efficient multi-functional small molecules to simultaneously solve these problems. Herein, conjugated small molecule 3-thiophenboric acid (TBA) was utilized for the first time at the SnO 2 /perovskite interface to achieve this goal. With the dipole moment of TBA, the energy level arrangement between SnO 2 and perovskite is optimized. Defects at both sides of the interface are passivated by functional groups on TBA effectively, inhibiting the non-radiative recombination and reducing the energy loss. Besides, the quality of perovskite film is improved due to inhibited disordered heterogeneous nucleation. As a result, the open voltage (V OC), short current density (J SC) and fill factor (FF) are all improved, which leads to a champion device with PCE up to 21.80%, much higher than 19.74% of control one. In addition, our optimized devices show excellent stability when storing for a long time, aging under high humidity and under continuous illumination. Our results provide a novel strategy to improve the efficiency and stability of PSCs synergistically by multi-functional conjugated small molecule. [ABSTRACT FROM AUTHOR]

Device-free passive intrusion detection is a promising technology to determine whether moving subjects are present without deploying any specific sensors or devices in the area of interest. With the rapid development of wireless technology, multi-input multi-output (MIMO) and orthogonal frequency-division multiplexing (OFDM) which were originally exploited to improve the stability and bandwidth of Wi-Fi communication, can now support extensive applications such as indoor intrusion detection, patient monitoring, and healthcare monitoring for the elderly. At present, most research works use channel state information (CSI) in the IEEE 802.11n standard to analyze signals and select features. However, there are very limited studies on intrusion detection in real home environments that consider scenarios that include different motion speeds, different numbers of intruders, varying locations of devices, and whether people are present sleeping at home. In this paper, we propose an adaptive real-time indoor intrusion detection system using subcarrier correlation-based features based on the characteristics of narrow frequency spacing of adjacent subcarriers. We propose a link-pair selection algorithm for choosing an optimal link pair as a baseline for subsequent CSI processing. We prototype our system on commercial Wi-Fi devices and compare the overall performance with those of state-of-the-art approaches. The experimental results demonstrate that our system achieves impressive performance regardless of intruder's motion speeds, number of intruders, non-line-of-sight conditions, and sleeping occupant conditions. [ABSTRACT FROM AUTHOR]

• Self-normalized nonlinear PCR is proposed to characterize ion-implanted Si wafers. • Comparison between self-normalized nonlinear PCR and conventional nonlinear PCR is performed. • Self-normalized nonlinear PCR shows improved accuracy and reliability for Si characterization. A self-normalized photocarrier radiometry (PCR) is proposed to characterize the electronic transport properties (minority carrier lifetime, carrier diffusion coefficient, and surface recombination velocity) of B+ ion-implanted silicon wafers via multi-parameter estimation. In self-normalized PCR the amplitude and phase measured from the implanted surface are normalized by that measured from the matte rear surface (non-implanted substrate) of the ion-implanted silicon wafer to eliminate the need to measure the instrumental frequency response which is a major error source of the multi-parameter estimation. Two- and single-layer nonlinear PCR models are employed respectively to describe the PCR signals measured from the implanted and matte rear surfaces of the wafers. The self-normalized PCR is applied to the simultaneous determination of the electronic transport parameters and the thickness of the implanted layer of the ion-implanted silicon wafers. Experimentally, the frequency dependences of PCR amplitude and phase measured from the implanted and rear surfaces under 830-nm excitation at 40.5 mW are measured for seven B+ ion-implanted silicon wafers with different implantation doses. The electronic transport parameters and thicknesses of the implanted layers are then determined by multi-parameter fitting the self-normalized PCR amplitude and phase to corresponding nonlinear PCR models, as well as determined by the conventional PCR via measuring the instrumental frequency response and subtracting its influence on the measured PCR signals of the ion-implanted wafers for comparison. The lower variances of multi-parameter fitting and improved uncertainties of the fitted transport parameters in the self-normalized PCR as compared to that in the conventional PCR corroborate the improved accuracy and reliability of the self-normalized PCR for the simultaneous determination of the electronic transport parameters of ion-implanted silicon wafers. [ABSTRACT FROM AUTHOR]