The sprayed ZnO films: nanostructures and physical parameters

We synthesized the pure and indium-doped (IZO) ZnO films with a facile composition control spray pyrolysis route. The substrate temperature (T_s) and In-doping effects on the properties of as-grown films are investigated. The X-ray pattern confirms that the as-synthesized ZnO phase is grown along a (002) preferential plane. It is revealed that the crystalline structure is improved with a substrate temperature of 350 ℃. Moreover, the morphology of as-grown films, analyzed by AFM, shows nanostructures that have grown along the c-axis. The (3 × 3μm²) area scanned AFM surface studies give the smooth film surface RMS < 40 nm. The UV-VIS-IR measurements reveal that the sprayed films are highly transparent in the visible and IR bands. The photoluminescence analysis shows that the strong blue and yellow luminescences of 2.11 and 2.81 eV are emitted from ZnO and IZO films with a slight shift in photon energy caused by In-doping. The band gap is a bit widened by In-doping, 3.21 eV (ZnO) and 3.31 eV (IZO) and the resistivity is reduced from 385 to 8 Ω ·m. An interesting result is the resistivity linear dependence on the substrate temperature of pure ZnO films.     

最大比合并接收系统在n-Rayleigh信道下的性能分析

在n-Rayleigh信道下,研究了MRC(Maximal Ratio Combining)合并接收系统的平均码字错误率(ASEP)性能。基于矩生成函数(MGF)的方法,推导了MRC接收系统在n-Rayleigh衰落信道上采用M进制相移键控(MPSK),M进制正交幅度调制(MQAM)和M进制脉冲幅度调制(MPAM)等几种M进制数字调制方式的ASEP的计算式。然后在不同条件下,仿真了系统的ASEP性能,仿真值与理论值相一致,理论分析的正确性得到了证明。分析结果表明:分集支路数和衰弱因子对系统的ASEP性能有重要影响。     

Modelling of nanostructured TiO2-based memristors

The fourth fundamental circuit element memristor completes the missing link between charge and magnetic flux. It consists of the function of the resistor as well as memory in nonlinear fashion. The property of the memristor depends on the magnitude and direction of applied potential. This unique property makes it the primitive building block for many applications such as resistive memories, soft computing, neuromorphic systems and chaotic circuits etc. In this paper we report TiO2-based nanostructured memristor modelling. The present memristor model is constructed in MATLAB environment with consideration of the linear drift model of memristor. The result obtained from the linear drift model is well matched with earlier reported results by other research groups.     

结温在线控制系统的IGBT功率模块热耦合模型

应用有限元法，对IGBT功率模块的三维热分布进行了仿真研究，得到了器件的稳态热阻及瞬态热阻抗。研究了功率模块各芯片之间的相互热影响，提出了热耦合效应热模型的统一结构，基于对瞬态热阻抗曲线的拟合，得到热模型的相关参数，从而建立了热耦合效应热模型。以一个降压变换器为例，阐述了结温在线控制系统的工作原理，并将热模型应用于该系统中，计算结果与测量结果非常一致。     

Time and reference frequency transfer over 850 nm VCSEL for digital telecommunication network synchronization

Accurate time transfer and synchronization between different network nodes is a key functional requirement in digital communication. Developments in optical fiber-based frequency dissemination techniques have improved optical frequency stability over time to much lower levels. In this work, we experimentally present the reference frequency transfer employing 850 nm vertical cavity surface emitting laser (VCSEL) over 100.3 m OM3 multimode fiber for synchronization of clocks on networked devices such as servers and racks/pod at different data center network nodes. A low-cost power-efficient multimode VCSEL with central wavelength at 844.26 nm is directly modulated with a 2 GHz reference frequency (RF) clock signal, and transferred over 100.3 m of OM3 multimode fiber. The single side band (SSB) phase noise of ?104.62 dBc/Hz and ?100.70 dBc/Hz is experimentally measured at back-to-back (B2B) and 100.3 m OM3 multimode fiber transmission respectively at a 1 kHz frequency offset. The jitter stability of 0.14 ps and 0.15 ps is experimentally achieved at B2B and 100.3 m fiber transmission, respectively. This work provides an alternative viable approach for the development of time keeping devices in high-speed short-reach optical communication systems.     

Hierarchical parameter identification in models of respiratory mechanics

Potential harmful effects of ventilation therapy could be reduced by model-based predictions of the effects of ventilator settings to the patient. To obtain optimal predictions, the model has to be individualized based on patients' data. Given a nonlinear model, the result of parameter identification using iterative numerical methods depends on initial estimates. In this work, a feasible hierarchical identification process is proposed and compared to the commonly implemented direct approach with randomized initial values. The hierarchical approach is exemplarily illustrated by identifying the viscoelastic model (VEM) of respiratory mechanics, whose a priori identifiability was proven. To demonstrate its advantages over the direct approach, two different data sources were employed. First, correctness of the approach was shown with simulation data providing controllable conditions. Second, the clinical potential was evaluated under realistic conditions using clinical data from 13 acute respiratory distress syndrome (ARDS) patients. Simulation data revealed that the success rate of the direct approach exponentially decreases with increasing deviation of the initial estimates while the hierarchical approach always obtained the correct solution. The average computing time using clinical data for the direct approach equals 4.77?s (SD = 1.32) and 2.41?s (SD = 0.01) for the hierarchical approach. These investigations demonstrate that a hierarchical approach may be beneficial with respect to robustness and efficiency using simulated and clinical data.     

Development of an active targeting liposome encapsulated with high-density colloidal gold for transmission electron microscopy

Active targeting of the liposome is an attractive strategy for drug delivery and in vivo bio-imaging. We previously reported the specific accumulation of Sialyl Lewis X (SLX) liposome to inflamed tissue in arthritic model mice or tumor-bearing mice. SLX-liposome encapsulation with fluorescent substances allows for the visualization of these liposomes by the time-dependent transvascular accumulation of fluorescent signals in the histological sections. In the present study, we developed a new SLX-liposome encapsulated with colloidal gold for transmission electron microscopic observation. We herein describe the characterization of the colloidal gold-loaded SLX-liposomes and demonstrate its specific targeting to the endothelial cells of tumor blood vessels in tumor-bearing mice.     

The inverse problem utilizing the boundary element method for a nonstandard female torso

This paper proposes a new method of rapidly deriving the transfer matrix for the boundary element method (BEM) forward problem from a tailored female torso geometry in the clinical setting. The method allows rapid calculation of epicardial potentials (EP) from body surface potentials (BSP). The use of EPs in previous studies has been shown to improve the successful detection of the life-threatening cardiac condition--acute myocardial infarction. The MRI scanning of a cardiac patient in the clinical setting is not practical and other methods are required to accurately deduce torso geometries for calculation of the transfer matrix. The new method allows the noninvasive calculation of tailored torso geometries from a standard female torso and five measurements taken from the body surface of a patient. This scaling of the torso has been successfully validated by carrying out EP calculations on 40 scaled torsos and ten female subjects. It utilizes the BEM in the calculation of the transfer matrix as the BEM depends only upon the topology of the surfaces of the torso and the heart, the former can now be accurately deduced, leaving only the latter geometry as an unknown.     

Odor discrimination using neural decoding of the main olfactory bulb in rats

This paper presents a novel method for inferring the odor based on neural activities observed from rats' main olfactory bulbs. Multichannel extracellular single unit recordings were done by microwire electrodes (tungsten, 50 μm, 32 channels) implanted in the mitral/tufted cell layers of the main olfactory bulb of anesthetized rats to obtain neural responses to various odors. Neural response as a key feature was measured by subtraction of neural firing rate before stimulus from after. For odor inference, we have developed a decoding method based on the maximum likelihood estimation. The results have shown that the average decoding accuracy is about 100.0%, 96.0%, 84.0%, and 100.0% with four rats, respectively.     

Shear elastic modulus estimation from indentation and SDUV on gelatin phantoms

Tissue mechanical properties such as elasticity are linked to tissue pathology state. Several groups have proposed shear wave propagation speed to quantify tissue mechanical properties. It is well known that biological tissues are viscoelastic materials; therefore, velocity dispersion resulting from material viscoelasticity is expected. A method called shearwave dispersion ultrasound vibrometry (SDUV) can be used to quantify tissue viscoelasticity by measuring dispersion of shear wave propagation speed. However, there is not a gold standard method for validation. In this study, we present an independent validation method of shear elastic modulus estimation by SDUV in three gelatin phantoms of differing stiffness. In addition, the indentation measurements are compared to estimates of elasticity derived from shear wave group velocities. The shear elastic moduli from indentation were 1.16, 3.40, and 5.6 kPa for a 7%, 10%, and 15% gelatin phantom, respectively. SDUV measurements were 1.61, 3.57, and 5.37 kPa for the gelatin phantoms, respectively. Shear elastic moduli derived from shear wave group velocities were 1.78, 5.2, and 7.18 kPa for the gelatin phantoms, respectively. The shear elastic modulus estimated from the SDUV, matched the elastic modulus measured by indentation. On the other hand, shear elastic modulus estimated by group velocity did not agree with indentation test estimations. These results suggest that shear elastic modulus estimation by group velocity will be bias when the medium being investigated is dispersive. Therefore, a rheological model should be used in order to estimate mechanical properties of viscoelastic materials.