Coil‐Capacitor Circuit Design of a Transcutaneous Energy Transmission System to Deliver Stable Electric Power

A new transcutaneous energy transmission (TET) system was developed for transmitting electrical power to an implanted device, such as an artificial heart in a patient's body. This new design can maintain a stable output voltage independent of the load resistance. The system includes a compensation capacitor to reduce energy loss and increase power transfer efficiency. Experimental results show that the output voltage of the receiving coil changes very little as the load resistance varies from 14.8 Ω to 15 kΩ, which corresponds to a change in output power from 0.1 to 97 W.     

Facile Fabrication and Superparamagnetism of Silica‐Shielded Magnetite Nanoparticles on Carbon Nitride Nanotubes

Using conventional methods to synthesize magnetic nanoparticles (NPs) with uniform size is a challenging task. Moreover, the degradation of magnetic NPs is an obstacle to practical applications. The fabrication of silica‐shielded magnetite NPs on carbon nitride nanotubes (CNNTs) provides a possible route to overcome these problems. While the nitrogen atoms of CNNTs provide selective nucleation sites for NPs of a particular size, the silica layer protects the NPs from oxidation. The morphology and crystal structure of NP–CNNT hybrid material is investigated by transmission electron microscopy (TEM) and X‐ray diffraction. In addition, the atomic nature of the N atoms in the NP–CNNT system is studied by near‐edge X‐ray absorption fine structure spectroscopy (nitrogen K‐edge) and calculations of the partial density of states based on first principles. The structure of the silica‐shielded NP–CNNT system is analyzed by TEM and energy dispersive X‐ray spectroscopy mapping, and their magnetism is measured by vibrating sample and superconducting quantum interference device magnetometers. The silica shielding helps maintain the superparamagnetism of the NPs; without the silica layer, the magnetic properties of NP–CNNT materials significantly degrade over time.     

Joint spectrum sensing and resource allocation optimization using genetic algorithm for frequency hopping–based cognitive radio networks

In cognitive radio (CR) networks, secondary users should effectively use unused licensed spectrums, unless they cause any harmful interference to the primary users. Therefore, spectrum sensing and channel resource allocation are the 2 main functionalities of CR networks, which play important roles in the performance of a CR system. To maximize the CR system utility, we propose a joint out‐of‐band spectrum sensing and operating channel allocation scheme based on genetic algorithm for frequency hopping–based CR networks. In this paper, to effectively sense the primary signal on hopping channels at each hopping slot time, a set of member nodes sense the next hopping channel, which is called out‐of‐band sensing. To achieve collision‐free cooperative sensing reporting, the next channel detection notification mechanism is presented. Using genetic algorithm, the optimum sensing and data transmission schedules are derived. It selects a sensing node set that participate the spectrum sensing for the next expected hopping channel during the current channel hopping time and another set of nodes that take opportunity for transmitting data on the current hopping channel. The optimum channel allocation is performed in accordance with each node's individual traffic demand. Simulation results show that the proposed scheme can achieve reliable spectrum sensing and efficient channel allocation.     

Excellent Switching Uniformity of Cu-Doped $hbox{MoO}_{x}/hbox{GdO}_{x}$ Bilayer for Nonvolatile Memory Applications

We have investigated a Cu-doped MoO_x/GdO_x bilayer film for nonvolatile memory applications. By adopting an ultrathin GdO_x layer, we obtained excellent device characteristics such as resistance ratio of three orders of magnitude, uniform distribution of set and reset voltages, switching endurance up to 10⁴ cycles, and ten years of data retention at 85degC. By adopting bilayer films of Cu-doped MoO_x/GdO_x, a local filament was formed by a two-step process. Improved memory characteristics can be explained by the formation of nanoscale local filament in the ultrathin GdO_x layer.     

韩国三星集团公司的市场策略

从产品开发,人才使用,结构调整,企业经营等8个方面,可以清楚看到韩国三星集团创“新”腾飞的足迹。     

Role of Cooper pairs for the generation of entangled photon pairs from single quantum dots

Generation of entangled photon pairs from semiconductor quantum dots (QDs) is highly desirable for realizing practical solid-state photon sources for quantum information processing and quantum cryptography. However, the energy splitting of exciton states in QDs almost prevent the generation of entangled photon pairs. This paper discusses the new possibility with the injection of electron as well as hole Cooper pairs into QDs.     

Pseudo‐3D RSSI‐based WSN localization algorithm using linear regression

Receiver Strength Signal Indication based Wireless Sensor Networks offer a cheap solution for location‐aware applications. For a final breakthrough these systems need fast deployment and easy auto‐configuration. In this study, we use the real‐life iMinds test bed to expand a two‐dimensional localization algorithm to the pseudo third dimension with very low additional computational time. Our experiments show that this fast three‐dimensional algorithm has no outliers and avoids manual calibration. Our algorithm has lower position errors than a maximum likelihood algorithm with a mean square error cost function. Furthermore, with non‐parametric statistical tests, we show that our previously designed two‐dimensional preprocessing performs equally well in pseudo‐three dimensions: the preprocessing reduces the position error in a statistically significant way.Copyright © 2013 John Wiley & Sons, Ltd.     

Squaraine Dyes for Photovoltaic and Biomedical Applications

Squaraine dyes (SQs) are an important class of polymethine dyes with a unique reasonable-stabilized zwitterionic structure, in which electrons are highly delocalized over the conjugated bridge. These dyes can not only be easily synthesized via a condensation, but also exhibit intense absorption and emission in the visible and near-infrared region with excellent photochemical stability, making them attractive material candidates for many photoelectric and biomedical applications. Thus, in this review, after an introduction of SQs, the recent advances of SQs in the photovoltaic field are comprehensively summarized including dye-sensitized solar cells, organic solar cells, and perovskite solar cells. Then, the important advances in the use of SQs as the biosensors, biological imaging, and photodynamic/photothermal therapy reagents in the biomedical field are also discussed. Finally, a summary and outlook will be provided with some new perspectives for the future design of SQs.     

Diurnal Variation of the AMSU-A Brightness Temperatures Over the Amazon Rainforest

Brightness temperatures over the Amazon rainforest are obtained from the Advanced Microwave Sounding Units (AMSU-A and AMSU-B) instruments onboard three NOAA satellites (NOAA-15, -16, and -17, respectively) for the months of July, August, and October, 2002. The three AMSU-A instruments provided six daily measurements, separated by 2.5-5.5 h of the diurnal time intervals, over the Amazon rainforest region, and these measurements offer a unique opportunity for investigation of the diurnal variation of the brightness temperatures over the Amazon rainforests. The angular distributions of brightness temperatures over the Amazon rainforest are very stable and can be simulated with a radiative transfer model, which consists of an atmospheric radiative component and a rainforest-canopy model that treats the rainforest as a uniform layer with an effective canopy temperature. The simulated results agree well with the observations. The diurnal variation of brightness temperatures over the Amazon rainforest is simulated with a Fourier-series model. It shows that a second order of Fourier series can reproduce the observed pattern of diurnal variation of the brightness temperatures at zenith angles of 0deg, 28.7deg, and 58.1deg, respectively. In a practical application, the coefficients of Fourier-series expansion can be used to generate the brightness temperatures as a function of diurnal hours. These results can be applied to postlaunch calibration of satellite-borne microwave radiometer with different equator crossing time. In addition, the results presented in this paper indicate that the Amazon rainforest can be used as a hot calibration reference target. The availability of a land calibration target is important for calibration and validation of spaceborne microwave radiometers     

亚马逊热带雨林星载SAR辐射定标算法

天线外定标是实现星载SAR天线方向图在轨测试的主要手段。天线方向图的准确测量,对星载SAR图像的应用具有重要作用。分布目标辐射定标在星载SAR天线方向图测试中受到广泛重视。亚马逊热带雨林的后向散射系数呈现大面积的均匀性和稳定性,故成为分布目标定标最主要的定标场。该文在分布目标定标原理的基础上,对基于亚马逊热带雨林的星载SAR天线方向图测量算法进行了研究,提出了采用K．Pearson统计量非参数假设检验的一致性处理算法,并采用Levenberg-Marquard算法（LM算法）估计俯仰向天线方向图模型参数。仿真数据验证了算法的可靠性和准确性。