Wideband spectrum sensing using step-sampling based on the multipath nyquist folding receiver

Wideband spectrum sensing with a high-speed analog-digital converter(ADC) presents a challenge for practical systems.The Nyquist folding receiver(NYFR) is a promising scheme for achieving cost-effective real-time spectrum sensing,which is subject to the complexity of processing the modulated outputs.In this case,a multipath NYFR architecture with a step-sampling rate for the different paths is proposed.The different numbers of digital channels for each path are designed based on the Chinese remainder theorem(CRT).Then,the detectable frequency range is divided into multiple frequency grids,and the Nyquist zone(NZ) of the input can be obtained by sensing these grids.Thus,high-precision parameter estimation is performed by utilizing the NYFR characteristics.Compared with the existing methods,the scheme proposed in this paper overcomes the challenge of NZ estimation,information damage,many computations,low accuracy,and high false alarm probability.Comparative simulation experiments verify the effectiveness of the proposed architecture in this paper.

Physicochemical Characterization of Photoelectrodes of Ti/TiO₂Prepared by Thermal Oxidation of Titanium

The preparation and study of supported TiO2 for photocatalytic application in solar cell devices is a relevant research field. Thin films of TiO2 prepared on Ti by thermal oxidation in a wide range of temperatures (450°C - 900°C) were characterized by electrochemical impedance spectroscopy, potentiometry and amperometry. This material presents photoelectrochemical activity, which depends dramatically of the oxidation temperature and the exposition time at the studied temperatures. The flatband potential as well as the donor density and the resistance to the charge transfer were measured. All these parameters are temperature dependent, and the optimal values are observed on the photoelectrodes prepared at 750°C. This result is consistent with the photochemical response reported in the literature for thin films of Ti/TiO2 prepared under similar conditions.

A Multi-Model Approach to Design a Robust SVC Damping Controller Using Convex Optimization Technique to Enhance the Damping of Inter-Area Oscillations Considering Time Delay

This paper introduces a multi-model approach to design a robust supplementary damping controller. The designed fixed-order supplementary damping controller adjusts the voltage reference set point of SVC. There are two main objectives of the controller design, damping low frequencies oscillations and enhancing power system stability. This method relies on shaping the closed-loop sensitivity functions in the Nyquist plot under the constraints of these functions. These constraints can be linearized by choosing a desired open-loop transfer function. The robust controller is designed to minimize the error between the open-loop of the original plant model and the desired transfer functions. These outcomes can be achieved by using convex optimization methods. Convexity of the problem formulation ensures global optimality. One of the advantages of the proposed approach is that the approach accounts for multi-model uncertainty. In contrast to the methods available in the literature, the proposed approach deals with full-order model (i.e., model reduction is not required) with lower controller order. The issue of time delay of feedback signals has been addressed in this paper for different values of time delay by applying a multi-model optimization technique. The proposed approach is compared to other existing techniques to design a robust controller which is based on H2 under pole placement. Both techniques are applied to the 68-bus system to evaluate and validate the robust controller performance under different load scenarios and different wind generations.

Flipped-Exponential Nyquist Pulse Technique to Optimize PAPR in Optical Direct-Detection OFDM Systems

In this paper, we describe a novel technique based on the flipped-exponential （FE） Nyquist pulse method for reducing peak-to-average power ratio （PAPR） in an optical direct-detection orthogonal frequency-division multiplexing （DD-QFDM） system, The technique involves proper selection of the FE Nyquist pulses for shaping the different subcarriers of the OFDM. We apply this technique to a DD-OFDM transmission system to significantly reduce PAPR. We also investigate the sensitivity of a received OFDM signal with strong nonlinearity in a standard single-mode fiber （SMF）.

Gamma irradiation-induced effects on the properties of TiO_2 on fluorine-doped tin oxide prepared by atomic layer deposition

The effect of gamma irradiation with different doses(25–75 kGy) on TiO_2 thin films deposited by atomic layer deposition has been studied and characterized by X-ray diffraction(XRD),photoluminescence measurements,ultraviolet–visible(UV–Vis) spectroscopy,and impedance measurements.The XRD results for the TiO_2 films indicate an enhancement of crystallization after irradiation,which can be clearly observed from the increase in the peak intensities upon increasing the gamma irradiation doses.The UV–Vis spectra demonstrate a decrease in transmittance,and the band gap of the TiO_2 thin films decreases with an increase in the gamma irradiation doses.The Nyquist plots reveal that the overall charge-transfer resistance increases upon increasing the gamma irradiation doses.The equivalent circuit,series resistance,contact resistance,and interface capacitance are measured by simulation using Z-view software.The present work demonstrates that gamma irradiation-induced defects play a major role in the modification of thestructural,electrical,and optical properties of the TiO_2 thin films.

A Historical Review of Robert van Gulik and His Judge Dee Mysteries in Chinese World （1996-2016）

Judge Dee Mysteries was written by a Dutch diplomat and orientalist Robert van Gulik, and has been translated into more than twenty languages, gaining a wide attention with the honorary title of ＂Orienta/Sherlock Holmes＂ in English world. It returned to China with Chen Laiyuan and Hu Ming＇s translations in 1980s, and since then there emerged various studies by Chinese scholars on Robert van Gulik and his works. This article makes a historical review of Judge Dee Mysteries in Chinese world during the past 20 years, presents problems in translating and introducing Robert van Gulik in Chinese, and proposes comments and suggestions for further translation and studies of Judge Dee Mysteries in a comparison with Chinese gong＇an fictions.

Intensity of the Reverse Sexual Double Standards in Females and Males and Possible Factors

Despite past researches on the sexual double standards(SDS),recent research has found that another type of sexual double standard exists,which is the reverse sexual double standard(i.e.reverse SDS,which means that men are judged more harshly than women in comparative sexual behaviors).According to previous researchers,the reverse SDS may stem from women’s worry about being infected by transmitted sexual diseases,women’s preference for men’s virginity in sexual behaviors,and the shift in attitude towards men’s sexual behaviors.Also,women tend to judge men’s sexual behaviors based on men’s attractiveness(body appearance and financial status).The present study investigated people’s implicit endorsement of the reverse SDS among 200 adults in Shanghai(20 to 50 years old,110 women,90 men)using the Implicit Association Test(IAT)with a priming procedure to limit participants’awareness including different levels of men’s body appearance and financial status.Additionally,SDSS(sexual double standard scale)was used to measure the explicit endorsement for the reverse SDS.According to my results,adults in Shanghai endorsed both an implicit and explicit reverse SDS,but women tend to endorse it more strongly than men.Also,when men are more attractive,women will judge them less harshly.These results indicate that the reverse SDS also exists in men.Implications and limitations are indicated for future researchers to call for attention to the reverse SDS and gender equality.

Intertextuality of Translations Into and From Judaeo-Arabic as a Transformative Platform in Jewish-Arabic Universalism:The Case of Legal Monographs of the Late Geonim

In medieval times,translators of Judaeo-Arabic literature living in Islamic lands were fluent in Arabic as this was the lingua franca and,in many cases,their mother tongue.This is only rarely the case for the contemporary scholar.This creates enormous challenges for the modern translators of their works.However,this challenge is an opportunity to bridge cultural and historical gaps by increased accuracy the hallmark of modern scholarship.This interdisciplinary discourse establishes the co-religious Dasein.The research tools which demand knowledge not only of Jewish sources but rather of Islamic texts allow for greater appreciation of contacting influences.Rav Y.al-Barceloni of the 12th century,among others,translated into Hebrew several works of the Geonim with his own halakhic interpretations,interpolations,and expansions.When scholars come today to comprehend anew,these compilations they paradoxically are more reflective of the original text than scholars of the middle ages who were contemporaneous with these texts.Nonetheless insofar as the translations are into Hebrew,they produce insular affect on the cultural product,leaving it within the Jewish fold.This fact forces scholars who desire to communicate with the broader audience to publish their results in European languages.In mediaeval studies,this is not as often as one thinks.

论WTO对安全例外条款扩张适用的规制

在单边主义、保护主义兴起背景下,部分WTO成员扩大安全例外条款适用范围的问题日益凸显。WTO争端解决实践确立了争端解决机构对成员援引该条款行为的管辖权,并就“基本安全利益”及“国际关系紧急情况”的适用作出阐述,对规制该条款的扩张适用具有积极作用。但WTO争端解决实践仍未形成对成员自裁决权的有效约束,非传统安全的适用问题尚待厘清,同时缺乏对成员措施实施的“必要性”审查,使安全例外条款仍存在被滥用的风险。为更好地解决部分成员任意扩张适用安全例外条款的问题,中国应积极向WTO争端解决机构提交第三方意见,建议其在与该条款有关的案件中采用严格的解释方法,并推动成员在WTO改革中对条款文本进行修改。

AutoCAD考试系统中图形数据的提取和自动评分

介绍了 Auto CAD考试系统中图形数据的表示和提取方法 ,讨论了自动评分功能模块的设计原理与实现过程 .

Praetor的实与名:从正名开始的罗马公法研究

古罗马的Praetor的名实问题,从翻译的角度说存在八种汉译,对Praetor官职从古罗马共和时期开始直到帝政时期的实际职掌,其最初是一种兼具行政、司法和军事职能的官职,只是到了帝政时期,Praetor才慢慢地转变为专业的司法官。因此,对Praetor一词的准确把握,应依据其在不同时期的不同职能进行,不能通译为裁判官,最好的释义是副执政官。

AutoCAD考试系统的研究与开发

文中介绍了AutoCAD考试系统的基本设计方法。利用DXF文件的方法开发了VB与AutoCAD之间图形数据交换的接口程序,从而把高级语言、数据库和绘图软件三者联接起来,实现了AutoCAD考试系统中图形数据的自动评分功能。

减速器系列参数绘图在AutoCAD上的实现

讨论了利用智能化尺寸驱动技术实现二维参数化绘图中的问题。首先讨论了几何约束、结构约束与约束判定的关系,基于此关系,利用图形尺寸参数和结构参数实现图形的尺寸驱动,进而利用智能化尺寸驱动法实现参数化绘图。以AutoCAD为平台,通过高级语言C与AutoLISP语言编程,在开发的圆柱齿轮减速器壳体自动化设计系统软件之参数化绘图中得以实现。

Bluetooth技术在体育比赛裁判器上的应用

介绍利用蓝牙无线技术,实现体育裁判信息收发和处理,具体介绍了裁判器的硬件实现方法,并给出了编程框图。

Selection of Judging Indicators for Surface Morphology of Soil Crack under Different Development Degrees in Yuanmou Arid-Hot Valley Region

Quantification of complicated surface morphology of soil crack is a prerequisite and key to soil crack study. This paper takes soil crack quads in Yuanmou arid-hot valley region as examples, selecting several morphological indicators, and analyzes the soil crack＇s morphological features under various development degrees. By statistic analysis, three quantitative indicators for surface morphology are selected, namely soil crack area density, area weighted mean fractal dimension and connectivity index R, which can not only express the development intensity of soil cracks, but also effectively describe its morphological complexity and connectivity. The research results set a good base for the establishment of soil crack assessment system in Yuanmou arid-hot valley region.

End-to-end rate-based congestion control with random loss:convergence and stability

The convergence and stability analysis for two end-to-end rate-based congestion control algorithms with unavoidable random loss in packets are presented, which can be caused by, for example, errors on wireless links. The convergence rates of these two algorithms are analyzed by linearizing them around their equilibrium points, since they are globally stable and can converge to their unique equilibrium points. Some sufficient conditions for local stability in the presence of round-trip delay are obtained based on the general Nyquist criterion of stability. The stability conditions can be considered to be more general. If random loss in the first congestion control algorithm is not considered, they reduce to the local stability conditions which have been obtained in some literatures. Furthermore, sufficient conditions for local stability of a new congestion control algorithm have also been obtained if random loss is not considered in the second congestion control algorithm.

对HUSTOJ在线评测系统的若干优化与创新

在原有HUSTOJ开源在线评测系统的基础之上,分别对系统的竞赛模式的类别、竞赛的权限设置、用户信息的处理、系统的数据库结构进行修改与创新。使得新的系统相比原有的系统竞赛方式更多样,竞赛和整个系统之间的数据更加的独立,不会产生相互的干扰;而且使得用户信息的统计更加科学和合理化。

CLINICAL OBSERVATION ON OSTEOPOROSIS TREATED WITH TRADITIONAL KIDNEY-TONIFYING MEDICAMENTS

The method of scoring kidney deficiency symptoms and bone density was used to judge therapeutic efficacy on osteoporosis of traditional kidney-tonifying drugs. It was proved that the drugs not only improved clinical symptoms but also delayed the developmental pro-cess of this disorder. It also verified the correctness of the traditional theory that the kidney dominates the bone and generates the marrow.

Design of a Fixed-Order Robust Controller to Damp Inter-Area Oscillations in Power Systems

This paper presents the design of a robust fixed-order H∞ controller to damp out the inter-area oscillations and to enhance the stability of the power system. The proposed H∞ approach is based on shaping the open-loop transfer function in the Nyquist diagram through minimizing the quadratic error between the actual and the desired open loop transfer functions in the frequency domain under linear constraints that guarantee robustness and stability. The proposed approach is robust with respect to multi-model uncertainty closed-loop sensitivity functions in the Nyquist diagram through the constraints on their infinity norm. The H∞ constraints are linearized with the help of a desired open-loop transfer function. The controller is designed using the convex optimization techniques in which the difference between the open-loop transfer function and the desired one is minimized. The two-area four-machine test system is selected to evaluate the performance of the designed controller under different load conditions as well as different levels of wind penetrations.

基于傅里叶系数实部的脉冲流信号欠Nyquist采样方法

有限新息率(FRI)采样理论可以远低于信号Nyquist频率的采样速率实现对脉冲流信号的欠采样。经典的FRI重构算法大多基于傅里叶系数进行运算,其中存在大量的对复数矩阵的奇异值分解,降低了算法的执行效率。针对该问题,该文提出基于傅里叶系数实部的脉冲流信号FRI采样及重构方法。首先利用离散余弦变换从脉冲流信号的低速采样值中获取其傅里叶系数实部信息,并在重构算法中使用实部的Toeplitz矩阵以提高奇异值分解(SVD)的效率;其次,为了提升经典的零化滤波器算法的鲁棒性,该文从傅里叶系数实部协方差矩阵的旋转不变特性以及零空间特性出发,提出基于离散余弦变换的协方差矩阵分解算法以及基于离散余弦变换的零空间搜索算法来估计脉冲流信号的特征参数,并针对出现的共轭根问题,提出基于交替方向乘子法的去共轭算法。仿真结果表明:在信号新息率较高的情况下,使用傅里叶系数实部信息会极大提高算法的执行效率,同时保证参数估计的准确性。