前沿文献阅读报告The introduction of photovoltaic

图像检测外文翻译参考文献(文档含中英文对照即英文原文和中文翻译)译文基于半边脸的人脸检测概要：图像中的人脸检测是人脸识别研究中一项非常重要的研究分支。

为了更有效地检测图像中的人脸，此次研究设计提出了基于半边脸的人脸检测方法。

根据图像中人半边脸的容貌或者器官的密度特征，比如眼睛，耳朵，嘴巴，部分脸颊，正面的平均全脸模板就可以被构建出来。

被模拟出来的半张脸是基于人脸的对称性的特点而构建的。

图像中人脸检测的实验运用了模板匹配法和相似性从而确定人脸在图像中的位置。

此原理分析显示了平均全脸模型法能够有效地减少模板的局部密度的不确定性。

基于半边脸的人脸检测能降低人脸模型密度的过度对称性，从而提高人脸检测的速度。

实验结果表明此方法还适用于在大角度拍下的侧脸图像，这大大增加了侧脸检测的准确性。

关键词：人脸模板，半边人脸模板，模板匹配法，相似性，侧脸。

I.介绍近几年，在图像处理和识别以及计算机视觉的研究领域中，人脸识别是一个很热门的话题。

作为人脸识别中一个重要的环节，人脸检测也拥有一个延伸的研究领域。

人脸检测的主要目的是为了确定图像中的信息，比如，图像总是否存在人脸，它的位置，旋转角度以及人脸的姿势。

根据人脸的不同特征，人脸检测的方法也有所变化[1-4]。

而且，根据人脸器官的密度或颜色的固定布局，我们可以判定是否存在人脸。

因此，这种基于肤色模型和模板匹配的方法对于人脸检测具有重要的研究意义[5-7]。

这种基于模板匹配的人脸检测法是选择正面脸部的特征作为匹配的模板，导致人脸搜索的计算量相对较大。

然而，绝大多数的人脸都是对称的。

所以我们可以选择半边正面人脸模板，也就是说，选择左半边脸或者有半边脸作为人脸匹配的模板，这样，大大减少了人脸搜索的计算。

II.人脸模板构建的方法人脸模板的质量直接影响匹配识别的效果。

为了减少模板局部密度的不确定性，构建人脸模板是基于大众脸的信息，例如，平均的眼睛模板，平均的脸型模板。

这种方法很简单。

图像复原技术研究国内外文献综述作为日常生活中广泛使用的技术，图像修复技术汇集了国内外许多重要技术。

实际上，图像复原分为三种标准：首先是搭建其劣化图像的图像模型；其次去研究和筛选最佳的图像复原方法；最后进行图像复原。

所有类型的成像模型和优化规则都会导致应用于不同领域的不同图像恢复算法。

我们对现有的图像复原方法大致做了总结，如利用线性代数知识的线性代数复原技术、搭建图像退化模型的去卷积图像恢复技术以及不考虑PSF的图像盲解卷积算法等。

其中，去卷积方法主要包括功率谱均衡、Wiener滤波和几何平均滤波等，然而这些方法需要许多预信息和噪声稳定假设，这在现实当中我们不可能利用计算机去做到的的事情，因此它们只适用于线性空间不变的理想系统，仅当噪声与信号无关时才能达到很好的效果。

但是在一些条件恶化的情况下，就不能满足图像修复的效果了。

在图像恢复领域当中，另一个重要且常见的方法是盲去卷积复原法。

它的优势是在没有预先了解退化函数和实际信号的知识前提下，可以根据劣化图像直接估计劣化函数和初始信号。

实际上，现在有几个算法通过不充分的预测信息来恢复劣化图像。

由于我们需要对图像和点扩展函数的一些相关信息进行假设和推导，所以这就导致图像恢复的解通常并不存在唯一性，并且我们已知的初始条件和对附加图像假设的选择也会对解的优劣产生很大的关系。

与此同时，由于信道中不可避免的加性噪声的影响，会进一步导致盲图像的复原变差，给图像复原造成许多困难。

也就是说，如果我们直接利用点扩展函数进行去卷积再现初始图像，则一般会导致高频噪声放大，导致算法的性能恶化，恢复不出清晰的图像。

因此，我们要尽可能的提高图像的信噪比，从而提高图像复原的效果。

基于已知的降质算子和加性噪声的某些统计性质从而恢复清晰的图像，我们将这种方法叫做线性代数恢复方法，并且这种线性代数恢复方法在一定程度上提出了用于恢复滤波器的数值计算从而使得模糊图像恢复到与清晰图像一致的新的设计思想。

Journal of Literature and Art Studies, July 2023, Vol. 13, No. 7, 492-498doi: 10.17265/2159-5836/2023.07.003An Analysis of the Phenomenon of Creative Treason inGoldblatt’s Translation of FrogTANG Zhi-yuCollege of Literature and Journalism, Sichuan University, Chengdu, ChinaLiterary transl ation should not solely focus on “what to translate”, but also on “how to translate”, exte nding theperspective to the target audience and environment. It is crucial to recognize that translation involves more thanrendering words; it entails navigating cultural differences and facilitating literary communication during theprocess of language conversion. By comparing and contrasting Mo Yan’s work of “蛙” with Howard Goldblatt’sEnglish translation Frog from both the two aspects of language and culture and the four perspectives of alienationand naturalization, deletion and addition, processing of address and dialogues, symbols of animal cultural, thisstudy explores the phenomenon of creative treason in literary translation, and provides a specific and in-depthanalysis to offer valuable insights for the translation of Chinese literature.Keywords: creative treason, Frog, translation, cultural differencesLiterary translation is not only to convert one text into another, but also to make an accurate grasp of the cultural characteristics and ideological connotations of the original text, and make appropriate changes on the basis of faithfulness to the original text. The success of literary translation should not only focus on “what to translate”, but also on “how to translate”, expand the perspective to the receiving group and the receiving environment, and realize that the translation of words is only an appearance, but the essence is the cultural difference and literary exchange in the process of language conversion. It can be said that the translator gives a second life to the literary work, which profoundly affects the popularity of the work abroad. The English translation of The Frogs helped author Mo Yan take the Nobel Prize for Literature in one go, which is undoubtedly a great success, and its dissemination and acceptance overseas cannot be separated from the translator Howard Goldblatt’s second creation. This paper compares Mo Yan’s work Frogs and Goldblatt’s English translation, and specifically explains and analyzes the phenomenon of creative rebellion, so as to provide a reference for the translation of Chinese literature.Introduction to FrogFrog is a full-length magical realism novel written by contemporary Chinese author Mo Yan, first published in 2009. Spanning the 1950s to the beginning of the 21st century, the story is set against the backdrop of the ups and downs of rural fertility in New China over the past 60 years, and uses the experience of Wan Xin,TANG Zhi-yu, Bachelor’s degree, College of Literature and Journalism, Sichuan University.a female doctor’s aunt, who has been practicing obstetrics and gynecology for more than 50 years, to paint a picture of the arduous and complex implementation of family planning policies, revealing sensitive social issues while portraying a group of characters of different shapes and sizes. The novel was awarded the 8th Mao Dun Literary Award in 2011. Subsequently, in 2012, Mo Yan achieved a historic milestone as the first Chinese author to be awarded the Nobel Prize in Literature because of Frog. The English version of Frog was skillfully translated by renowned American sinologist and translator, Howard Goldblatt. Initially published in Australia in 2014, it later made its way to the UK and the US in 2015. Its publication coincided with its inclusion in the Washington Post’s prestigious “2015 Novels to Watch” list. This successful publication and distribution of the English translation significantly amplified the global appeal and popularity of Frog.Analysis of Creative Treason in the English Translation of Frog Creative treason was first proposed by French literary sociologist Robert Escarpit, who who explains in his book Sociology of Literature that “it is always an act of creative treason, but it is still treason because it puts the work into a system of references (linguistic, in this example) for which it was not originally conceived-creative, because it gives new reality to the work in providing it with the possibility of a new literary interchange with a larger public and because it assures not only mere survival but a second existence” (Escarpit, 1971, p. 85). From this perspective, creative treason in translation involves more than superficial changes to the language’s form; it also allows the translator to make decisions on whether to creatively adapt the text based on the cultural characteristics and ideological connotations of the target country, while remaining faithful to the original ideas and expressions.Howard Goldblatt, the English translator of Frog, possesses a nuanced understanding of Chinese culture, owing to his prior study experience in China. During the process of translating Mo Yan’s work, Goldblatt adeptly navigated the differences in cultural concepts, historical development, and ideological connotations between China and the United States. His flexible approach to translation garnered the approval and support of the original author, Mo Yan. The translation exhibits a noticeable creative treason, primarily evident in two levels: linguistic and cultural adaptations, including alienation and naturalization, deletion and addition, processing of address and dialogues, symbols of animal cultural. This scholarly and culturally sensitive translation not only showcases Goldblatt’s expertise but also contributes to an enriched cross-cultural literary exchange, further enhancing the global appreciation and recognition of Mo Yan’s masterpiece Frog.Creative Treason at the Level of LanguageAlienation and NaturalizationAlienation and naturalization, initially introduced by American translator Lawrence Venuti, are key characteristics of personalized translation. “Alienation” entails the translator adhering closely to the author’s expressions in the source language to convey the original content effectively. These two concepts are essentially opposite yet complementary. On the other hand, “naturalization”involves adopting expressions familiar to the target language readers to effectively convey the original content.(ST) 那些曾以人体器官或身体部位命名的孩子，也大都改成雅名，当然也有没改的，譬如陈耳，譬如陈眉。

Morphology-photovoltaic property correlation in perovskite solar cells: One-step versus two-step deposition of CH3NH3PbI3Jeong-Hyeok Im, Hui-Seon Kim, and Nam-Gyu ParkCitation: APL Materials 2, 081510 (2014); doi: 10.1063/1.4891275View online: /10.1063/1.4891275View Table of Contents: /content/aip/journal/aplmater/2/8?ver=pdfcovPublished by the AIP PublishingArticles you may be interested inDouble functions of porous TiO2 electrodes on CH3NH3PbI3 perovskite solar cells: Enhancement of perovskite crystal transformation and prohibition of short circuitingAPL Mat. 2, 081511 (2014); 10.1063/1.4891597Mechanical properties of hybrid organic-inorganic CH3NH3BX3 (B = Sn, Pb; X = Br, I) perovskites for solar cell absorbersAPL Mat. 2, 081801 (2014); 10.1063/1.4885256CdS quantum dots grown by in situ chemical bath deposition for quantum dot-sensitized solar cellsJ. Appl. 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Lett. 90, 143517 (2007); 10.1063/1.2721373APL MATERIALS2,081510(2014)Morphology-photovoltaic property correlation in perovskite solar cells:One-step versus two-step depositionof CH3NH3PbI3Jeong-Hyeok Im,Hui-Seon Kim,and Nam-Gyu Park aSchool of Chemical Engineering and Department of Energy Science,SungkyunkwanUniversity,Suwon440-746,South Korea(Received21April2014;accepted14July2014;published online28July2014)Perovskite CH3NH3PbI3light absorber is deposited on the mesoporous TiO2layervia one-step and two-step coating methods and their photovoltaic performances arecompared.One-step coating using a solution containing CH3NH3I and PbI2showsaverage power conversion efficiency(PCE)of7.5%,while higher average PCE of13.9%is obtained from two-step coating method,mainly due to higher voltage andfill factor.The coverage,pore-filling,and morphology of the deposited perovskiteare found to be critical in photovoltaic performance of the mesoporous TiO2basedperovskite solar cells.©2014Author(s).All article content,except where otherwisenoted,is licensed under a Creative Commons Attribution3.0Unported License.[/10.1063/1.4891275]Perovskite solar cell is emerging photovoltaic technology because of low cost and high efficiency. Since the reports on the all-solid-state perovskite solar cells with power conversion efficiencies (PCEs)of∼10%in2012,1,2rapid progress has been made for the past one and half years.As a consequence,PCEs as high as over16%have been achieved.3,4CH3NH3PbI3and CH3NH3PbI3-x Cl x are currently the front-and-center materials for high efficiency perovskite solar cell.Since perovskite wasfirst used as a sensitizer in dye-sensitized type solar cell in the early stage,5,6perovskite has been tried to be deposited on the surface of TiO2.Spin-coating of the solutions containing CH3NH3I and PbI2for CH3NH3PbI3or CH3NH3I and PbCl2for CH3NH3PbI3−x Cl x led to the scattered nanodots1 or extremely thin layer.2This method requires infiltration of hole transporting material(HTM),such as2,2 ,7,7 -tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene(spiro-MeOTAD),into the pores of the metal oxidefilms.Photovoltaic performance relies significantly on the extent of pore-filling with HTM.This issue was addressed byfilling the pores with perovskite instead of HTM,7 which resulted in a PCE of12%.Building up the perovskite thin layer in the mesoporous metal oxide matrix(nanocomposite structure)eventually led to construction of heterojunction structure without the metal oxide layer.4Recent progress in perovskite solar cell and its basic understanding can be found in the latest literatures.8–12For pore-filling with CH3NH3PbI3perovskite,sequential deposition technique via two-step dipping was found to one of effective ways to achieve reproducibly high efficiency perovskite solar cell.3Average PCE of12%with small standard deviation of±0.5was obtained using two-step dipping method.A slight modification of dipping condition led to a PCE of15%.It was mentioned that uncontrolled precipitation of CH3NH3PbI3perovskite in a single step deposition produced large morphological variation and thereby inconsistent photovoltaic performance.However,no compara-tive study between the one-step and two-step deposition has been carried out.Here we have studied morphology and photovoltaic performance depending on deposition procedure of CH3NH3PbI3. We performed two-step sequential spin-coating procedure for CH3NH3PbI3deposition which was slightly different from two-step dipping method.3Both one-step and two-step coating methods a Author to whom correspondence should be addressed.Electronic mail:npark@.Tel.:+82-31-290-7241.Fax: +82-31-290-7272.2,081510-12166-532X/2014/2(8)/081510/8©Author(s)2014resulted in reproducible photovoltaic performance,but significant difference in especially photo-voltage andfill factor.Electron life time was dependent on coating procedure.Such difference in photovoltaic performance was found to correlate to morphology of the deposited CH3NH3PbI3.CH3NH3I was synthesized according to method reported in Ref.6.Methylamine(27.86ml, 40%in methanol,TCI)and hydroiodic acid(30ml,57wt.%in water,Aldrich)were mixed at0◦C and stirred for2h.The precipitate was recovered by evaporation at50◦C for1h.The product was washed with diethyl ether three times and thenfinally dried at60◦C in vacuum oven for24h.Anatase TiO2nanoparticles with diameter of∼40nm were synthesized by two-step hydrother-mal method.The seed particles with diameter of∼20nm were synthesized by acetic acid catalyzed hydrolysis of titanium isopropoxide(97%,Aldrich)and autoclaving at230◦C for12h.The seed particles were washed with ethanol and collected using centrifuge.Hydrothermal treatment was performed again with the seed particles to grow the particle size.TiO2paste was prepared by mixing the TiO2particles(∼40nm)with terpineol(99.5%,Aldrich),ethyl cellulose(EC)(46cp,Aldrich), and lauric acid(LA)(96%,Fluka)at nominal ratio of TiO2:TP:EC:LA=1.25:6:0.6:0.1.The paste was further treated with three-roll-mill for40min.FTO(Fluorine-doped Tin Oxide)glass substrate(Pilkington,TEC-8,8 /sq)with dimension of 2.5cm×2.5cm was cleaned in an ultrasonic bath containing ethanol for20min,which was treated in UVO(Ultraviolet Ozone)cleaner for20min.TiO2blocking layer(BL)was spin-coated on a FTO substrate at2000rpm for20s using0.15M titanium diisopropoxide bis(acetylacetonate)(75wt.% in isopropanol,Aldrich)in1-butanol(99.8%,Aldrich)solution,which was heated at125◦C for 5min.After cooling down to room temperature,the TiO2paste was spin-coated on the BL layer at 2000rpm for10s,where the pristine paste was diluted in ethanol(0.1g/ml).After drying at100◦C for5min,thefilm was annealed at550◦C for30min.The mesoporous TiO2film was immersed in 0.02M aqueous TiCl4(>98%,Aldrich)solution at90◦C for10min.After washing with de-ionized (DI)water and drying,thefilm was heated at500◦C for30min.To make the perovskite precursor solution,the synthesized CH3NH3I(0.395g)was mixed with PbI2(1.157g,99%Aldrich)in2ml N,N-dimethylacetamide(DMA,>99%Sigma)at60◦C for12h under stirring.Twenty microliters perovskite precursor solution was spin-coated on the mesoporous TiO2layer at3000rpm for20s.Thefilm was dried consecutively at40◦C for3min and100◦C for5min.Twenty microliters of spiro-MeOTAD solution was spin-coated on the CH3NH3PbI3 perovskite layer at4000rpm for30s.A spiro-MeOTAD solution was prepared by dissolving 72.3mg of spiro-MeOTAD in1ml of chlorobenzene,to which28.8μl of4-tert-butyl pyridine(TBP) and17.5μl of lithium bis(trifluoromethanesulfonyl)imide(Li-TFSI)solution(520mg Li-TSFI in 1ml acetonitrile(Sigma-Aldrich,99.8%))were added.Finally,an80-nm-thick gold electrode was thermally deposited on the spiro-MeOTAD coatedfilm.The one substrate containsfive cells and the photoactive layer of each cell was ca.0.2cm2(Figure S1of the supplementary material).13 In1ml N,N-dimethylformamide(DMF,99.8%Sigma-Aldrich),462mg PbI2was dissolved at 70◦C to make1M PbI2solution.Twenty microliters PbI2solution was spin-coated on the meso-porous TiO2layer at3000rpm for20s,which was dried at40◦C for3min and100◦C for5min consecutively.One hundred microliters of0.063M CH3NH3I solution in2-propanol(Aldrich) (10mg/ml)was loaded on the PbI2-coated substrate for20s,which was spun at4000rpm for 20s and then dried at100◦C for5min.It took4s to reach4000rpm,the duration for acceleration. The HTM and Au layer were formed by the same way in the one-step coating procedure.Photocurrent and voltage were measured from a solar simulator equipped with450W Xenon lamp(Newport6279NS)and a Keithley2400source meter.Light intensity was adjusted with the NREL-calibrated Si solar cell having KG-2filter for approximating one sun light intensity (100mW cm−2).While measuring current and voltage,the cell was covered with a black mask having an aperture.Incident photon-to-electron conversion efficiency(IPCE)was measured using a specially designed IPCE system(PV measurement,Inc.).A75W Xenon lamp was used as a light source for generating monochromatic beam.Calibration was accomplished using a silicon photodiode,which was calibrated using the NIST-calibrated photodiode G425as a standard.IPCE data were collected at DC mode.Afield-emission scanning electron microscope(FE-SEM,Jeol JSM6700F)was used to investigate surface and cross sectional morphology of the perovskite solar cells.FIG.1.One-step and two-step spin-coating procedures for CH3NH3PbI3formation.PbI2was mixed with CH3NH3I in N,N-dimethylacetamide(DMA),which was spin-coated and heated for one-step coating.For two-step coating,a PbI2-dissolved N,N-dimethylformamide(DMF)solution wasfirst spin-coated on the substrate,dried and then a CH3NH3I-dissolved isopropyl alcohol(IPA)solution was spin-coated on the PbI2coated substrate.For transient photovoltage measurement,535nm and680nm of wavelength lasers were used as probe and bias light source,respectively.The probe light was incident over the bias light generating steady-state charge where the incident charge was rapidly decreased showingfirst order exponential decay.Both light intensities were varied by a neutral densityfilter.The transient photovoltage signal was amplified using a low-noise preamplifier,Stanford Research System SR560and monitored by an oscilloscope,TDS3054B.Impedance spectra were measured in dark with an Autolab302B with varying a bias potential from0V to1.0V where the potential step is0.1V.AC20mV perturbation was applied with a frequency from1MHz to1Hz.The resulted impedance spectra werefit using Z-View software.The Nyquist plots and the bestfit results(Figure S2of the supplementary material)13 based on an equivalent circuit were described in the supplementary material.In Figure1one-step and two-step coating procedures are schematically illustrated.For one-step coating of CH3NH3PbI3,the DMA solution containing equimolar CH3NH3I and PbI2is spin-coated on the mesoporous TiO2layer.PbI2is formedfirst for two-step coating procedure,which was followed by spin-coating the CH3NH3I solution.In two-step procedure,compared to two-step dipping method,3two-step spin-coating procedure is well defined method because of quantitatively managed process.The amount of CH3NH3I and spin-coating condition should be carefully adjusted in terms of the amount of deposited PbI2.For coating with20μl of1M PbI2solution,100μl of0.063M CH3NH3I is found to be sufficient to convert PbI2into CH3NH3PbI3as confirmed by no presence of PbI2peak in X-ray diffraction spectrum(data are not shown).Detailed method for two-step coating is described in the experimental part.As can be seen in SEM images in Figure2,morphology of the deposited CH3NH3PbI3is remarkably different.One-step coating produces shapeless CH3NH3PbI3(Figure2(b)),whereas cube-like crystals are formed by two-step coating method(Figure2(c)).Besides morphological difference,TiO2layer is not completely covered by the perovskite using one-step spin-coating method compared to full coverage with perovskite by two-step coating procedure.Insufficient coverage in one-step coating is probably related to wettability,associated with high ionic strength (1.25M of CH3NH3+and Pb2+and3.75M of I−)of coating solution,14and/or competition betweenpositive ions of CH3NH3+and Pb2+.Contrary to one-step method,close packing with cube-likeFIG.2.Surface SEM images(left:low magnification,right:high magnification)of(a)mesoporous TiO2coating on the compact blocking layer deposited FTO substrate,(b)one-step deposition of CH3NH3PbI3on the mesoporous TiO2layer, and(c)two-step deposition of CH3NH3PbI3on the mesoporous TiO2layer.crystal with dimension of about100–150nm is induced by two-step method,which indicates that spin-coating of20μl of1M solution of PbI2in DMF covers fully the TiO2film.PbI2is layered structure and well known to undergo intercalation reaction,15in which Lewis base molecules such as pyridine and methylamine were found to be intercalated into interlayer of PbI2.It was mentioned that charge transfer was not obvious during intercalation reaction and the dipole moment of Lewis base molecule or hydrogen bonding by the N–H bond was necessary requirement for intercalation.Thus, reaction of PbI2with CH3NH3I may be regarded as pseudo-intercalation because I−in CH3NH3I salt acts as an electron donor.Reaction of PbI2with I−forms presumably(PbI3)−via I2-I−interaction, which is followed by reaction with CH3NH3+to form CH3NH3PbI3.It was reported that a vacuum deposited PbI2was converted to CH3NH3PbI3when it was dipped in CH3NH3I solution,where full conversion required more than1h.16However,solution processed PbI2film reduces significantly reaction time for conversion.According to single crystal X-ray diffraction analysis,need-like crystals collected after cooling1M solution of PbI2in DMF revealed that one DMF molecule was coordinated to Pb via oxygen bridge.17Thus,substitution of CH3NH3I for DMF could also explain the two-step formation of CH3NH3PbI317and the faster reaction than the vacuum deposited PbI2beginning with surface reaction.Investigation from cross-sectional SEM images also confirms imperfect pore-filling of per-ovskite by one-step coating,which leads to contact between FTO and HTM as can be seen in Figure3. On the other hand,pores are completelyfilled with perovskite by using two-step coating.As can be seen in schematic illustrations based on SEM images,one-step coating leads to perovskite island but two-step one results in void-free perovskite layer.Mesoporous TiO2layer thickness is about 100nm and perovskite overlayer is around200nm.Photovoltaic parameters are plotted in Figure4,where the data obtained from40cells arestatistically analyzed.All the parameters of two-step deposited perovskite are superior to those ofFIG.3.Cross sectional SEM images of(a)one-step deposition of CH3NH3PbI3and(b)two-step deposition of CH3NH3PbI3. One-step deposition leads to imperfect pore-filling as shown in the high magnification SEM image.Two-step deposition showsthat pores of TiO2layer are fullyfilled with CH3NH3PbI3as confirmed by void-free interface.FIG.4.Short-circuit current density(Jsc),open-circuit voltage(V oc),fill factor(FF),and power conversion efficiency(PCE) for the perovskite solar cells based on one-step and two-step deposition procedure.The data were statistically analyzed from40cells.FIG.5.Normalized IPCE for the perovskite solar cells based on one-step(black line)and two-step(red line)process.one-step deposited one.Average short-circuit current density(J sc),open-circuit voltage(V oc),fill factor(FF),and power conversion efficiency(PCE)of19.15mA/cm2,0.828V,0.470,and7.5%are observed from the one-step deposited perovskite solar cells,while higher values of21.47mA/cm2, 1.024V,0.634,and13.9%are obtained from the two-step deposited ones.Standard deviation for PCE is as small as±0.6and±0.4for the one-step and two-step deposited devices,respectively, which indicates that the data are reproducible.Morphology-property relation can explain difference in photovoltaic performance.Higher J sc for the two-step deposition is due to better pore-filling of perovskite compared to its island structure for the one-step deposition.As shown in Figure3,the absence of perovskite at FTO interface loses absorption of short wavelength light,asfirmed by IPCE measurement in Figure5,which is responsible for lower J sc for one-step deposition.Recombination kinetics of devices based on one-step and two-step procedure are investigated using a transient photovoltage measurement and impedance spectra.The electron life time is obtained from a transient photovoltage signal byfitting it withfirst order exponential decay.In the transient photovoltage measurement the electron life time is strongly dependent on the light intensity where strong light intensity induces high electron and hole density and thus,a fast recombination is resulted. Contrariwise,longer electron life time is attributed to the lower density of electron and hole induced by weak light intensity.18It is reported that CH3NH3PbI3perovskite solar cell also shows the power law dependence of electron life time on the light intensity or open circuit voltage,19,20as shown in Figure6(a).The electron life time of two-step deposited perovskite is about one order of magnitude longer than that of one-step implying that the recombination kinetics highly depends on the perovskite structure determined by deposition method.This suggests that the voids generated in one-step coating allow HTM to infiltrate into perovskite layer,which increases a potential recombination site and leads ten times faster recombination than in two-step deposited perovskite.The recombination resistance is obtained from impedance spectra where thefirst arc in high frequency region is related to the transport in sprio-MeOTAD21and the second arc is related to the recombination.22,23The two arcs arefitted using a simplified equivalent circuit(resistance-parallel resistance,capacitance-parallel resistance,and capacitance in series)and the resulted recombination resistance(R r)is plotted as a function of an applied bias voltage in Figure6(b).R r shows little change in the low applied voltage (V app<0.5V)region but it starts to decrease rapidly as the Fermi level in photoanode increases by applying high bias voltage(V app>0.5V).1R r for one-step and two-step deposited perovskite are similar as expected in the region of low applied voltage(V app<0.5V),but R r for one-step shows lower value than that for two-step as the applied bias voltage increases more than0.5V describing that the recombination kinetics for one-step is faster than that of two-step perovskite. This result is also accordance with the tendency of electron life time.Likewise,the two-stepperovskite shows enhanced recombination kinetics due to its well established layer with free-voidparison of(a)electron life time for one-step(black)and two-step(red)deposited perovskite with varying open circuit voltage and(b)recombination resistance for one-step(black)and two-step(red)deposited perovskite by applying bias voltage.enabling to prevent the HTM infiltration and thus decrease the recombination probability.The lowered recombination rate for two-step deposited perovskite layer has a significant impact on the open-circuit voltage24leading200mV higher V oc than that for one-step deposited perovskite.It was reported that photovoltaic performance was found to be strongly dependent on degree of perovskite pore-filling,where decrease in perovskite pore-filling fraction led to deterioration of J sc,V oc,and fill factor.25In addition,incomplete perovskite pore-filling resulted in fast charge recombination of the injected electron in TiO2with spiro-MeOTAD.25Thus,we propose here that removal of the exposed TiO2allowing unwanted contact with spiro-MeOTAD is important to improve photovoltaic performance of the mesoporous TiO2based perovskite solar cell.Photovoltaic property-morphology relation was systematically evaluated from the diverse depo-sition methodologies of perovskite CH3NH3PbI3.Reproducible photovoltaic parameters extracted from statistical analysis were found to have strong correlation with the morphology of the deposited perovskite along with degree of the perovskite coverage.Recombination kinetics was significantly affected by the resulting morphology of the perovskite.The exposed TiO2by one-step coating was responsible for fast recombination and short electron life time.On the other hand,the complete pore-filling with perovskite by two-step method resulted in a significant improvement of photo-voltaic performance.It is concluded that photovoltaic performance is strongly dependent on degree of perovskite coverage on the mesoporous TiO2layer and morphology of the deposited perovskite in the mesoporous TiO2based perovskite solar cells.This work was supported by the National Research Foundation of Korea(NRF)grants funded by the Ministry of Science,ICT&Future Planning(MSIP)of Korea under Contract Nos.NRF-2010-0014992,NRF-2012M1A2A2671721,NRF-2012M3A7B4049986(Nano Material Technol-ogy Development Program),and NRF-2012M3A6A7054861(Global Frontier R&D Program on Center for Multiscale Energy System).H.S.K.is grateful to NRF for funding the global Ph.D.grant. 1H.-S.Kim,C.-R.Lee,J.-H.Im,K.-B.Lee,T.Moehl,A.Marchioro,S.-J.Moon,R.Humphry-Baker,J.-H.Yum,J.E. Moser,M.Gr¨a tzel,and N.-G.Park,Sci.Rep.2,591(2012).2M.M.Lee,J.Teuscher,T.Miyasaka,T.N.Murakami,and H.J.Snaith,Science338,643(2012).3J.Burschka,N.Pellet,S.-J.Moon,R.Humphry-Baker,P.Gao,M.K.Nazeeruddin,and M.Gr¨a tzel,Nature(London)499, 316(2013).4M.Liu,M.B.Johnston,and H.J.Snaith,Nature(London)501,395(2013).5A.Kojima,K.Teshima,Y.Shirai,and T.Miyasaka,J.Am.Chem.Soc.131,6050(2009).6J.-H.Im,C.-R.Lee,J.-W.Lee,S.-W.Park,and N.-G.Park,Nanoscale3,4088(2011).7J.H.Heo,S.H.Im,J.H.Noh,T.N.Mandal,C.-S.Lim,J.A.Chang,Y.H.Lee,H.-j.Kim,A.Sarkar,M.K.Nazeeruddin, M.Gr¨a tzel,and S.I.Seok,Nat.Photon.7,486(2013).8N.-G.Park,J.Phys.Chem.Lett.4,2423(2013).9H.J.Snaith,J.Phys.Chem.Lett.4,3623(2013).10H.-S.Kim,S.H.Im,and N.-G.Park,J.Phys.Chem.C118,5615(2014).11S.Kazim,M.K.Nazeeruddin,M.Gr¨a tzel,and S.Ahmad,Angew.Chem.Inter.Ed.53,2812(2014).12P.P.Boix,K.Nonomura,N.Mathews,and S.G.Mhaisalkar,Mater.Today17,16(2014).13See supplementary material at /10.1063/1.4891275for the real device configuration and for the Nyquist plots and theirfits based on an equivalent circuit.14R.Steitz,W.Jaeger,and R.V.Klitzing,Langmuir17,4471(2001).15C.C.Coleman,H.Goldwhite,and W.Tikkanen,Chem.Mater.10,2794(1998).16K.Liang,D.B.Mitzi,and M.T.Prikas,Chem.Mater.10,403(1998).17A.Wakamiya,M.Endo,T.Sasamori,N.Tokitoh,Y.Ogomi,S.Hayase,and Y.Murata,Chem.Lett.43,711–713(2014). 18K.Zhu,S.-R Jang,and A.J.Frank,J.Phys.Chem.Lett.2,1070(2011).19D.Bi,S.-J.Moon,L.Haggman,G.Boschloo,L.Yang,E.M.J.Johansson,M.K.Nazeeruddin,M.Gr¨a tzel,and A.Hagfeldt, RCS Adv.3,18762(2013).20Y.Zhao,A.M.Nardes,and K.Zhu,J.Phys.Chem.Lett.5,490(2014).21F.Fabregat-Santiago,J.Bisquert,L.Cevey,P.Chen,M.Wang,S.M.Zakeeruddin,and M.Gr¨a tzel,J.Am.Chem.Soc. 131,558(2009).22H.-S.Kim,I.Mora-Sero,V.Gonzalez-Pedro,F.Fabregat-Santiago,E.J.Juarez-Perez,N.-G.Park,and J.Bisquert,Nat. Commun.4,2242(2013).23H.-S.Kim,J.-W.Lee,N.Yantara,P.P.Boix,S.A.Kulkarni,S.Mhaisalkar,M.Gr¨a tzel,and N.-G.Park,Nano Lett.13, 2412(2013).24A.Zaban,M.Greenshtein,and J.Bisquert,Chem.Phys.Chem.4,859(2003).25T.Leijtens,uber,G.E.Eperon,S.D.Stranks,and H.J.Snaith,J.Phys.Chem.Lett.5,1096(2014).。

PhotovoltaicsPhotovoltaics (PV) is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panelscomposed of a number of solar cells containing a photovoltaic material. Materials presently used for photovoltaics include monocrystalline silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, and copper indium galliuselenide/sulfide.Due to the growing demand for renewable energy sources, the manufacturing of solar cells and photovoltaic arrays has advanced considerably in recent years.Solar photovoltaics is growing rapidly, albeit from a small base, toa total global capacity of 67,400 megawatts (MW) at the end of 2011, representing0.5% of worldwide electricity demand.The total power output of the world’s PV capacity run over a calendar year is equal to some 80 billion kWh of electricity. This is sufficient to cover the annual power supply needs of over 20 million households in the world.More than 100 countries use solar PV. Installations may be ground-mounted (and sometimes integrated with farming and grazing)or built into the roof or walls of a building (building-integrated photovoltaics).Driven by advances in technology and increases in manufacturing scale and sophistication, the cost of photovoltaics has declined steadily since the first solar cells were manufactured and the levelised cost of electricity (LCOE) from PV is competitive with conventional electricity sources in an expanding list of geographic regions. Net metering and financial incentives, such as preferential feed-in tariffs for solar-generated electricity, have supported solar PV installations in many countries. With current technology, photovoltaics recoup the energy needed to manufacture them in 1 to 4 years.Solar cellsPhotovoltaics are best known as a method for generating electric power by using solar cells to convert energy from the sun into a flow of electrons. The photovoltaic effect refers to photons of light exciting electrons into a higher state of energy, allowing them to act as charge carriers for an electric current. The photovoltaic effect was first observed by Alexandre-Edmond Becquerel in 1839. The term photovoltaic denotes the unbiased operating mode of a photodiode in which current through the device is entirely due to the transduced light energy. Virtually all photovoltaic devices are some type of photodiode.Solar cells produce direct current electricity from sun light, which can be used to power equipment or to recharge a battery. The first practical application of photovoltaics was to power orbiting satellites and other spacecraft, but today the majority of photovoltaic modules are used for grid connected power generation. In this case an inverter is required to convert the DC to AC. There is a smaller market for off-grid power for remote dwellings, boats, recreational vehicles, electric cars,roadside emergency telephones, remote sensing, and cathodic protection of pipelines.Photovoltaic power generation employs solar panels composed of a number of solar cells containing a photovoltaic material. Materials presently used for photovoltaics include monocrystalline silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, and copper indium gallium selenide/sulfide. Due to the growing demand for renewable energy sources, the manufacturing of solar cells and photovoltaic arrays has advanced considerably in recent years.Cells require protection from the environment and are usually packaged tightly behind a glass sheet. When more power is required than a single cell can deliver, cells are electrically connected together to form photovoltaic modules, or solar panels. A single module is enough to power an emergency telephone, but for a house or a power plant the modules must be arranged in multiples as arrays.A significant market has emerged in off-grid locations for solar-power-charged storage-battery based solutions. These often provide the only electricity available. The first commercial installation of this kind was in 1966 on Ogami Island in Japan to transition Ogami Lighthouse from gas torch to fully self-sufficient electrical power.Due to the growing demand for renewable energy sources, the manufacture of solar cells and photovoltaic arrays has advanced dramatically in recent years.Solar photovoltaics is growing rapidly, albeit from a small base, to a total global capacity of 67,400 megawatts (MW) at the end of 2011, representing 0.5% of worldwide electricity demand.The total power output of the world’s PV capacity run over a calendar year is equal to some 80 billion kWh of electricity. This is sufficient to cover the annual power supply needs of over 20 million households in the world.More than 100 countries use solar PV. World solar PV capacity(grid-connected) was 7.6 GW in 2007, 16 GW in 2008, 23 GW in 2009, and 40 GW in 2010. More than 100 countries use solar PV. Installations may be ground-mounted (and sometimes integrated with farming and grazing) or built into the roof or walls of a building (building-integrated photovoltaics).Photovoltaic power capacity is measured as maximum power output under standardized test conditions (STC) in "Wp" (Watts peak). The actual power output at a particular point in time may be less than or greater than this standardized, or "rated," value, depending on geographical location, time of day, weather conditions, and other factors. Solar photovoltaic array capacity factors are typically under 25%, which is lower than many other industrial sources of electricity.The EPIA/Greenpeace Advanced Scenario shows that by the year 2030, PV systems could be generating approximately 1.8 TW of electricity around the world. This means that, assuming a serious commitment is made to energy efficiency, enoughsolar power would be produced globally in twenty-five years’ time to satisfy the electricity needs of almost 14% of the world’s population.Current developmentsPhotovoltaic panels based on crystalline silicon modules are encountering competition in the market by panels that employ thin-film solar cells (CdTe CIGS,amorphous Si, microcrystalline Si), which had been rapidly evolving and are expected to account for 31 percent of the global installed power by 2013. However, precipitous drops in prices for polysilicon and their panels in late 2011 have caused some thin-film makers to exit the market and others to experience severely squeezed profits.Other developments include casting wafers instead of sawing, concentrator modules, 'Sliver' cells, and continuous printing processes.The San Jose-based company Sunpower produces cells that have an energy conversion ratio of 19.5%, well above the market average of 12–18%.The most efficient solar cell so far is a multi-junction concentrator solar cell with an efficiency of 43.5%produced by the National Renewable Energy Laboratory in April 2011. The highest efficiencies achieved without concentration include Sharp Corporation at 35.8% using a proprietary triple-junction manufacturing technology in 2009, and Boeing Spectrolab (40.7% also using a triple-layer design). A March 2010 experimental demonstration of a design by a Caltech group led by Harry Atwater which has an absorption efficiency of 85% in sunlight and 95% at certain wavelengths is claimed to have near perfect quantum efficiency. However, absorption efficiency should not be confused with the sunlight-to-electricity conversion efficiency.For best performance, terrestrial PV systems aim to maximize the time they face the sun. Solar trackers achieve this by moving PV panels to follow the sun. The increase can be by as much as 20% in winter and by as much as 50% in summer. Static mounted systems can be optimized by analysis of the sun path. Panels are often set to latitude tilt, an angle equal to the latitude, but performance can be improved by adjusting the angle for summer or winter. Generally, as with other semiconductor devices, temperatures above room temperature reduce the performance of photovoltaics.A number of solar panels may also be mounted vertically above each other in a tower, if the zenith distance of the Sun is greater than zero, and the tower can be turned horizontically as a whole and each panels additionally around a horizontical axis. In such a tower the panels can follow exactly the Sun. Such a device may be described as a ladder mounted on a turnable disk. Each step of that ladder is the middle axis of a rectangular solar panel. In case the zenith distance of the Sun gets zero, the “ladder” may be rotated to the north or the south to avoid that a solar panel produces a shadow on a lower mounted solar panel. Instead of an exactly vertical tower one can choose a tower with an axis directed to the polar star, meaning that it is parallel to the rotation axis of the Earth. In this case the angle between the axis and the Sun is always larger than 66 degrees. During a day it is only necessary to turn the panels around this axis to follow the Sun.The 2011 European Photovoltaic Industry Association (EPIA) report predicted that, "The future of the PV market remains bright in the EU and the rest of the world," the report said. "Uncertain times are causing governments everywhere to rethink the future of their energy mix, creating new opportunities for a competitive, safe and reliable electricity source such as PV." 2012 could see the installation of20–30 GW of PV —about the same as in 2011. Unfortunately, the industry's capacity continues to expand, to perhaps as much as 38 GW. The resulting glut of supply has crushed prices and profits. By 2015, 131–196 GW of photovoltaic systems could be installed around the globe.EconomicsThe output of a photovoltaic array is a product of the area, the efficiency, and the insolation. The capacity factor, or duty cycle, of photovoltaics is relatively low, typically from 0.10 to 0.30, as insolation ranges, by latitude and prevailing weather, and is location specific from about 2.5 to 7.5 sun hours/day. Panels are rated under standard conditions by their output power. The DC output is a product of the rated output times the number of panels times the insolation times the number of days. The sunlight received by the array is affected by a combination of tilt, tracking and shading. Tracking increases the yield but also the cost, both installation and maintenance. A dual axis tracker can increase the effective insolation by roughly 35-40%, while temperature effects can reduce efficiency by 10%. The AC output is roughly 25% lower due to various losses including the efficiency of the inverter. For example, for a 4 kW array in Paris, where the average insolation is 3.34 sun hours/day, the annual (AC) output would be approximately3.34x4x365x0.75=3657 kWh, and the monthly output, from the following chart, would range from 67 kWh in December to 498 kWh in July. The weather strongly affects the output and from year to year monthly and annual outputs can vary substantially. Published insolation values are normally 10 year averages. There are many live data sites that can be monitored, and compared.Financial incentives for photovoltaics, such as feed-in tariffs, have often been offered to electricity consumers to install and operate solar-electric generating systems. Government has sometimes also offered incentives in order to encourage the PV industry to achieve the economies of scale needed to compete where the cost of PV-generated electricity is above the cost from the existing grid. Such policies are implemented to promote national or territorial energy independence, high tech job creation and reduction of carbon dioxide emissions which cause global warming. Due to economies of scale solar panels get less costly as people use and buy more — as manufacturers increase production to meet demand, the cost and price is expected to drop in the years to come.NREL compilation of best research solar cell efficiencies from 1976 to 2010According to Shi Zhengrong, in 2012 unsubsidized PV systems already produce electricity in some parts of the world, more cheaply than coal and gas-fired power plants.[40][41] As PV system prices decline it is inevitable that subsidies will end. "Rapid decline or outright disappearance has already been seen in all the major solar markets except China and India".As of 2011, the price of PV modules per MW has fallen by 60 percent since the summer of 2008, according to Bloomberg New Energy Finance estimates, putting solar power for the first time on a competitive footing with the retail price of electricity in a number of sunny countries. There has been fierce competition in the supply chain, and further improvements in the levelised cost of energy for solar lie ahead, posing a growing threat to the dominance of fossil fuel generation sources in the next few years.As time progresses, renewable energy technologies generally get cheaper, while fossil fuels generally get more expensive:The less solar power costs, the more favorably it compares to conventional power, and the more attractive it becomes to utilities and energy users around the globe. Utility-scale solar power can now be delivered in California at prices well below $100/MWh ($0.10/kWh) less than most other peak generators, even those running on low-cost natural gas. Lower solar module costs also stimulate demand from consumer markets where the cost of solar compares very favorably to retail electric rates.As of 2011, the cost of PV has fallen well below that of nuclear power and is set to fall further. The average retail price of solar cells as monitored by the Solarbuzz group fell from $3.50/watt to $2.43/watt over the course of 2011.For large-scale installations, prices below $1.00/watt were achieved. A module price of 0.60 Euro/watt (0.78 $/watt) was published for a large scale 5-year deal in April 2012. In some locations, PV has reached grid parity, which is usually defined as PV production costs at or below retail electricity prices (though often still above the power station prices for coal or gas-fired generation without their distribution and other costs). Photovoltaic power is also generated during a time of day that is close to peak demand (precedes it) in electricity systems with high use of air conditioning. More generally, it is now evident that, given a carbon price of $50/ton, which would raise the price of coal-fired power by 5c/kWh, solar PV will becost-competitive in most locations. The declining price of PV has been reflected in rapidly growing installations, totaling about 23 GW in 2011. Although some consolidation is likely in 2012, due to support cuts in the large markets of Germany and Italy, strong growth seems likely to continue for the rest of the decade. Already, by one estimate, total investment in renewables for 2011 exceeded investment in carbon-based electricity generation.ApplicationsPower stationsMain articles: Solar parks and solar farms and List of photovoltaic power stationsMany solar photovoltaic power stations have been built, mainly in Europe.As of May 2012, the largest photovoltaic (PV) power plants in the world are the Charanka Solar Park (India, 214 MW), Golmud Solar Park (China, 200 MW), Agua Caliente Solar Project USA 100 MW) Perovo Solar Park (Ukraine 100 MW), Sarnia Photovoltaic Power Plant (Canada, 97 MW), Brandenburg-Briest Solarpark (Germany 91 MW), Solarpark Finow Tower (Germany 84.7 MW), Montalto di Castro Photovoltaic Power Station (Italy, 84.2 MW), Eggebek Solar Park (Germany 83.6 MW), Senftenberg Solarpark (Germany 82 MW), Finsterwalde Solar Park (Germany, 80.7 MW), Okhotnykovo Solar Park (Ukraine, 80 MW), Lopburi Solar Farm (Thailand 73.16 MW), Rovigo Photovoltaic Power Plant (Italy, 72 MW), and the Lieberose Photovoltaic Park (Germany, 71.8 MW).There are also many large plants under construction. The Desert Sunlight Solar Farm under construction in Riverside County, California and Topaz Solar Farm being built in San Luis Obispo County, California are both 550 MW solar parks that will use thin-film solar photovoltaic modules made by First Solar.The Blythe Solar Power Project is a 500 MW photovoltaic station under construction in Riverside County, California. The California Valley Solar Ranch (CVSR) is a 250 megawatt (MW) solar photovoltaic power plant, which is being built by SunPower in the Carrizo Plain, northeast of California Valley.The 230 MW Antelope Valley Solar Ranch is a First Solar photovoltaic project which is under construction in the Antelope Valley area of the Western Mojave Desert, and due to be completed in 2013. The Mesquite Solar project is a photovoltaic solar power plant being built in Arlington, Maricopa County, Arizona, owned by Sempra Generation.Phase 1 will have a nameplate capacity of 150 megawatts.Many of these plants are integrated with agriculture and some use innovative tracking systems that follow the sun's daily path across the sky to generate more electricity than conventional fixed-mounted systems. There are no fuel costs or emissions during operation of the power stations.In buildingsPhotovoltaic arrays are often associated with buildings: either integrated into them, mounted on them or mounted nearby on the ground.Arrays are most often retrofitted into existing buildings, usually mounted on top of the existing roof structure or on the existing walls. Alternatively, an array can be located separately from the building but connected by cable to supply power for the building. In 2010, more than four-fifths of the 9,000 MW of solar PV operating in Germany were installed on rooftops.Building-integrated photovoltaics (BIPV) are increasingly incorporated into new domestic and industrial buildings as a principal or ancillary source of electrical power. Typically, an array is incorporated into the roof or walls of a building. Roof tiles with integrated PV cells are also common.A 2011 study using thermal imaging has shown that solar panels, provided there is an open gap in which air can circulate between them and the roof, provide a passive cooling effect on buildings during the day and also keep accumulated heat in atnight.The power output of photovoltaic systems for installation in buildings is usually described in kilowatt-peak units (kWp).太阳能电池太阳能电池又称为“太阳能芯片”或光电池，是一种利用太阳光直接发电的光电半导体薄片。

翻译纳米医学是一个新兴的领域，在成像，诊断和治疗疾病的非侵入性的战略发展提供了巨大的承诺。

适应广泛的潜在应用开发和平台技术至关重要的，因为在体内响应的复杂性和毒性研究也是费时和昂贵的性质。

硅及其氧化物衍生物已成为一个潜在的针对手段和药物输送，可满足各种血管内和胃肠道的应用。

到目前为止，在体内成像和跟踪硅粒子使用约束增强的光激活或通过掺入的成像剂，如荧光标记物，顺磁化合物（常规磁共振成像，核磁共振成像）或放射性核素（例如，已经实现正电子发射断层扫描）。

核磁共振成像技术在体内研究和临床诊断是一个有吸引力的，因为它是非侵入性的，产生高解剖分辨率，无需电离辐射。

然而，由于小的磁矩的原子核，大量的晶核在常规条件下成像所需的。

增加MRI信号的方法之一是增加远远超出了其均衡值，这种技术被称为极化偏振。

超极化惰性气体结构渐露头角的肺部成像，而超极化13C和15N的代谢物已被用于研究在肿瘤学中的代谢和pH 。

极化的关键要求是从一个高度极化源靶核的角动量转换。

例如，在惰性气体实验角动量源是光学兴奋的碱金属蒸气。

对于液体状态的代谢物这一势头源还代谢物（低温动态核极化， DNP ），或与有机金属催化剂的组合仲氢结合的自由基（未成对电子）的自旋。

在MRI中使用硅是特别有吸引力的有以下几个原因。

首先，核磁矩的Si接近的13C和15N ，把它的商业多核MRI系统的调谐范围内。

其次，直接成像的 Si本质上是无背景，因为身体只含有微量硅的自然。

第三，由于原生硅由稀浓度（4.6％）在一个无原子核自旋的晶格原子核自旋为1 / 2的Si硅原子核之间的偶极相互作用，弱以及它们的结晶电场不敏感（唯一的自旋1/2核）的结果在相当长的弛豫时间T1 （长达几个小时，在高纯度的样品）的相干时间T2几秒钟，晶格不敏感方向或旋转。

第四，虽然很少有未成对电子的高纯度结晶硅的大部分范围内，含有未成对电子的表面缺陷是普遍存在于天然存在的硅/氧化硅（ SiO2）的接口（图1a）。

西方古史研究对图像史料的采集和运用作者：王以欣《光明日报》（2016年05月21日11版）传统的中国史学主要依赖书面史料，推崇官方正史而轻视稗官野史。

至于图像资料，尽管中国的书画传统悠久，刊印的文学古籍也常有插图出现，但史家绝少采用这些资料。

随着近代摄影术和现代印刷术的传入，考古学、艺术史、历史地理学等相关学科的引入，尤其是20世纪西方年鉴学派引发的“史料革命”的影响，国内史学研究才逐渐关注图像的补史证史功能。

最近，国内史学界受英国牛津学者彼得·伯克所著《图像证史》的影响，试图在理论和实践上构建图像史学的新学科，将图像史料的功能和利用上升到理论的层面。

反观西方史学传统，尤其是近代发展，对图像史料的采集和利用有着深厚渊源，并非只是20世纪的新潮。

一、古代文明中图像史料的丰富性西方古史研究的对象主要是古典希腊罗马文明和近东诸文明，它们都有丰富的图像遗存，尤其是古埃及。

古埃及人出于宗教原因将死者尸体制成木乃伊，并制作死者雕像，作为其灵魂依归之所。

雕像务须酷似本人，以便灵魂识别并投入其中。

古埃及人的象形文有如色彩丰富的绘画，他们留下的纸草文献，尤其是《亡灵书》，也同样图文并茂，将古埃及的冥世观念及丧葬风俗生动直观地以视觉形式表现出来。

壁画也是古埃及人留给后世的丰厚文化遗产。

存世的坟墓壁画，除宗教和神话题材外，多反映墓主人生前的世俗生活，其中不乏历史事件的记述。

还有那些随葬的陶土模型，是生活劳动场景的三维立体呈现。

两河流域也是最早的文明发源地之一，其造型艺术的写实性虽逊色于埃及，但也有丰富的表现力。

除了表现神、精灵、祭司、崇拜者和统治者的各种程式化雕像外，还有各种碑铭（编年史和纪念碑等），附有人物和历史事件的浮雕图案，涉及战争、祭祀、神庙和土木工程建设等众多主题，如贝希斯敦铭文。

另有数不胜数的滚筒式印章，其上的图案涉及宗教、神话等诸多题材。

壁画所存不多，保存相对较好的马里宫殿壁画，历史文化价值很高。

信息工程学院毕业设计文献综述姓名：学号：专业:班级：此栏为论文题目作者姓名：（塔里木大学信息工程学院＊*系＊＊班，电话号码）摘要：在图像处理中，图像滤波起着重要作用。

它可以有效地抑制（平滑）各种噪声、保持边缘信息，从而改善后续处理工作的质量（如提高图像分割精度等）。

图像滤波的方法有很多,比如说中值滤波、均值滤波、高斯滤波、维纳滤波等，中值滤波是基于排序统计理论的一种能有效抑制噪声的非线性信号处理技术，均值滤波是把每个像素都用周围的8个像素来做均值操作，高斯滤波实质上是一种信号的滤波器，其用途是信号的平滑处理，本文着重对中值滤波、均值滤波和高斯滤波进行分析，进一步了解它们的原理、特点、改进的算法及其应用.关键词：图像；滤波；中值滤波；均值滤波；高斯滤波一、引言图像滤波就是采用一定的算法对数字图像进行处理，以获得人眼视觉或者某种接受系统所需要的图像处理过程。

［1]对图像滤波的要求是，既能滤除图像中的噪声又能保持图像的细节。

[2］由于噪声和图像细节的混叠，所以在图像滤波中，图像的去噪与细节的保留往往是一对矛盾。

数字图像滤波技术是20世纪60年代发展起来的一门新兴学科,随着图像滤波理论和方法的进一步完善，［3］使得数字图像滤波技术在各个领域得到了广泛应用，并显示出广阔的应用前景。

面对数字化时代的来临，图像滤波知识显得越来越重要，实际上图像滤波已经渗透到计算机、电子、地质、气象、医学等诸多领域.二、正文1、＊＊的发展状况图像滤波的发展大致经历了初创期、发展期、普及期和实用化期4个阶段.初创期开始于20世纪60年代，当时的图像采用像素型光栅进行少秒显示，大多采用中、大型机对其处理.[5］在这一时期，由于图像存储成本高、处理设备昂贵，其应用面很窄。

进入20世纪70年代的发展期，开始大量采用中、小型机进行处理，图像处理也逐渐改用光栅扫描方式，特别是CT和卫星遥感图像的出现，对图像处理技术的发展起到了很好的推动作用。

虚拟示波器外文翻译文献综述(文档含中英文对照即英文原文和中文翻译)外文：A DAQ card based mixed signal virtual oscmoscopeAbstractComplex signals find many applications in SONAR, RADAR，Echo Location Systems and for studying the resonant frequencies. Digital StorageOscilloscopcs(DSO) is used these days for acquisition and display of routine signals. This instrument, found in every measurement laboratory, though potent in displaying simple periodic waveforms like sinusoids fails when frequency-varying time signals are applied, This problem surfaces because the underlying technique of oscilloscope used to trigger the waveform does not acquiesce with complex signals like chirp. Ready solution to this problem is the mixed signal oscilloscope. This is a costly solution and small laboratories cannot afford to have the costly instruments. In this paper, a cost effective DAQ card based mixed signal virtual 0scilloscope is proposed to study the complex signals. An intelligent technique, Weighted Hamming Distance (WHD) algorithm was used to accurately trigger the complex waveforms. Also for frequency domain analysis, Joint Time Frequency Analysis(JTFA)techniques were used. A LabVlEW'TM based virtual instrument was designed and developed with a capability to acquire, display and analyze the triggered signal. The integrated programming language LabVIEWTM was chosen as it offers many simple ready to use functions. In a way the proposal offers a cost effective, fast and flexible solution to treat the complex signals. The need to create such solutions is the consequence of costly hardware systems. The deficiency of conventional hardware. Scheme for the virtual oscilloscope for complex signals with some real time experimental results are presented in this work.Kevywords: Virtual instrumentation,Chirp signal,Data acquisition,Triggering, Complex signals, JTFA1.IntroductionFor the last two decades there has been a tremendous progress in computer technology. Measurement domain is no longer left unaffected. The way measurements are being done is totally revolutionized. Computer based measurement or say virtual instrumentation is gradually replacing the costly bench top instrumentation as it offers flexible,fast and cost effective solutions. Various classical instrumentation systems namely Oscilloscope, Multimeters and Spectrum analyzers ect. are almost phased out by their counter part virtual instrumentation. Our research extends the trend and demonstrates the developmen of the computer based mixed signal digital oscilloscope.Conventional signals such as the sinusoids have a constant frequency and the amplitede only varies with time throughout the signal definition. On the other hand, complex signals can be defined in this context as signals in which all the parameters vary. Fig.1 shows a typical complex signal i.e. Linear Chirp.Variation of amplitude and frequency with time can easily be understood by having a look at the signal. This requires a visually stable display of signal. The complex signal offers challenges f'or acquisition, display an analysis. Even the conventional modern age DSO is not capable of displaying and analyzing complex signals because these instruments employ simple triggering technique like level trigger. The conventional technnique of voltage trigger apparently fails when complex signals like chirp are analyzed on DSO. This is due to the very fact that these instruments consider chirp as a conventional sine wave and trigger for each cycle of the sine wave instead of triggering for the complete chirp cycle. This analysis of the chirp signal as several sine waveforms of different frequencies leadsthe DSO to display them as sinusoids in quick succession. As this rapid change occues at a very high rate and because of human eye not registering events occurring faster than 1/20th of a second the display appears as several overlapped sine waves. In the recent work[1], a new triggering technique was proposed for the complex signals based on WHD. Subsequent sections present the solution to the problem. For analysis of the complex signals in frequency domain JFFA technique is utilized and implemented[2-6].DSO uses the level trigger to display the waveform applied to it. This leads to trigger interval and the number of samples for this trigger interval is computed and these numbers of samples are display. The DSO considers the interval as the fundamental time period of the whole waveform and thus takes tbat much samples from its buffer and starts displaying it in quick succession. With simple waveform like a sine wave, level trigger can achieve stable display because trigger interval contains same number of cycles. This is shown in Fig. 2a.Now for the complex signal as shown in Fig.2b, level triggering produces a trigger interval having variable number of cycles for the same number ofsamples/time resulting in a visually unstable display.The actual trigger interval should be one complete cycle for a chirp signal as indicated in Fig. 2c. Having done this the repeated chirp signal for this time durationwill be displayed without any overlapping components as long as the entire time period is displayed.To observe the shortcomings experimentally in display of complex signals on the oscilloscope Tektronix dual channel signal generator AFG-3022 (250 MS/s, 25 MHz) was used to generate a chirp signal by choosing the sweep mode to sine waveform with its frequency varying linearly with respect to time. This signal was fed to TektronixTDS-2022 (2 GS/s, 200MHz) dual-channel DSO. The overlapping display as shown in Fig. 3 was observed.2. Intelligent method of triggeringAccurate triggering lies solely on correct identification of the time period of waveform under consideration. For this purpose, pattern recognition scheme was implemented to identify the pattern in the signal [1] and thus obtain the time periodof one complete cycle of the chirp. First, a fixed number of samples N are taken as reference pattern. Then the signal is shifted by one sample to form the test pattern. This pattern is then tested for its closeness' to the reference pattern. Closeness' can be defined as the distance by which test pattern is away from reference pattern.WHD is used as the decision function for closeness. Hamming distance is defined for two binary vectors as the number of different' bits are given their vectors. In WHD the different bits are given their binary weighting according to the bit position and their weights according to the bit position and their weights are summed up. WHD of two binary n bit number x and a is given byIf X and A are two binary vectors of n-bits element, then WHD for these two vectors is computed by summing up the element by element WHD and is given byFor a vector of dimension N, the samples are shifted N times and its closeness is computed at each shift.When these computations are done, the difference洫in the signals is found to be minimum (ideally zero when no noise) when the cycle repeated itself. Following are the major steps involved and implemented for intelligent trigger mechanism.1. Acquiring the long enough signal using DAQ card and to convert the decimal values of samples into binary form.2.A fixed number(N) of binary samples are stored in array. The stored samples are shifted by a fixedc number of samples, n (=1,inthis case).3. The original saved samples and the shifted samples are XORed bit-by-bit.The result is then multiplied by a factor of 2, where I represent the position of bit.4.The summation of all the resulting values gives the WHD for nth shifts.5.A plot of WHD vs. n is made and the minimum is calculated by peak detection method. The difference between two successive minima is the trigger interval in number of samples.6. The number of samples multiplied by the sampling rate results in trigger interval (in seconds).As a test case WHD algorithm is implemented for the following triangular waveforrn in Fig.4.The waveform is sampled at 8 points per eycle. Each sampled value is 3 bit length.The step by step implementation is given below.WHD waveforrn is plotted using WHD(1), WHD(2), …, WHD(8), and the location of the minima gives the triggering interval. Fig.5 shows the WHD waveform also clearly indicating the trigger interval at 8th sample.The WHD VI(Fig.6) was developed for this task. It takes the waveform, whose triggering interval is to be found, and the no of samples, on which computation is to be done, as input and outputs the sample at which minima occurs along with the value of minima and the WHD waveform. For typical chirp signal WHD waveform is obtained as shown in Fig.7. The number of samples between two consecutiveminima is equal to the number of samples in one cycle of the waveform. The product of the number of samples with the sampling interval is the triggering interval of the input signal. Thus, the virtual instrument could also display complex waveforms with considerable aese. Fig.7 shows triggering interval of 5 cycles.3. Frequency domain analysisFor simple signals the frequency analysis is performed by traditional tools like FFT. For such signals the Fourier Transform works well as their frequency components remain constant throughout the signal existence and hence there is no need for the time-frequency relationship. In case of complex signals the frequency varies with time. FFT fails to analyze these signals as it gives information about the frequency and its amplitude. Time information is lost.In order to overcome this difficulty, there are JTFA tools iike Short Time Fourier Transform(STFT) and Wavelet Transform. These are implemented for the signals under consideration.The STFT is a modified form of Fourier Transform. In this technique the signal is rnultiplied with a window function and their product's Fourier Transform (2).The main principle behind this technique is that the window function(w) breaks down the signal into segments of small finite durtion. The frequency component of the signal during this segment is assumed to be constant. By computing the Fourier Transform for this segment the frequency vs. amplitude information is obtained. Then the window is moved to another segment by a step having the same duration as the previous one giving the frequency component for that segment. Thus the frequency for different time intervals gives time-frequency relationship.However, there is a disadvantage with this tecnique. The size of the window function used is fixed, thus STFT will have same resolution for low and high frequencies. Resolution is the certainty by which one can determine time or frequency information. It is generally seen that a larger window leads to better frequency resolution and a small window leads to better time resolution. Thus, it depends upon the user whether he wants frequency or time resolution. Even if there is a need for change of resolution, the user has to do the same manually.To overcome the resolution problern, a more advanced technique called Wavelet Transform is used these days. In this the window size can be altered, using a scaling parameter a. The equation for Wavelet Transform is given as wherea is the scaling parameter,b is the translation parameter,x(t) is the signal to beanalyzed andis the wavelet functionThe wavelet function <(t) is known as the mother wavelet．Its scaled and time shifted versions are known as the daughter wavelets. These daughter wavelets having varying size offer different frequency and time resolutions at different frequencies. The scale parameter a represents the freequency component in an inverse relation. Thus the valuc of scale is inversely proportional to frequency component.Initially the wavelet function has scale a=1and is placed at the starting of thesignal. The wavelet transform and thus the frequency component of that segment. Then the wavelet function is moved by b steps and the wavelet transform is computed for that segment. This procecdure is continued till the end of the signal. Thus Wavelet transform for a=1 and all the time steps till the end of signal gets computed. Similarly the wavelet function is again placed at the start of the signal but with changed value of scale a. The procedure is continued till the Wavelet transform for each scale and time step combination has been computed.It can be observed that the computation of Wavelet Transform leads to a lot of redundancy.To reduce the redundancy, the scale values and the time steps can be linked using dyadic sampling. a= 2" and b=k 2' where n and k are integers. This leads to reduction in redundancy. This is called Discrete Wavelet Transform(DWT).4. ImplementationA DAQ card based virtual instrument was designed and developed inLabVIEW TM programming environment. This virtual instrument has the capability to generate intelligent software trigger as described above for complex waveforms like chirp. The main decisionns during design of the virtual instrument are: choosing the data acquisition card and, what is equally important, choosing the set of features the instrument should offer. The choice of the data acquistion card has a great influence on the efficiency of the whole instrument[7，8].Particular DAQ cards are differentiated by price and, the specification it offers.A low cost NIPCI-6035E, 16bit, 200KS/s card was chosen. The hardware was programmed at maximum sampling rate. A separate problem is designing software, which, in that case, is the main part of instrument design phase. The major features of the developed virtual instrument are:The capability to acquire and process simple and complex waveforms.Dual channel mode: The instrument is capable of displaying two inputs simultaneously and can perform simple math operations between the two.Auto set: Runs the WHD code to re-compute the trigger interval for the new signal and thus achieve a stable display. In case, the two inputs do not have the same frequency, the LCM of the trigger intervals of A and B is found to so that integral number of cycles of both the channels can be shown simultaneously.Time domain measurements: The signal being displayed in time domain are measured on various parameters-Amplitude-Peak to peak -Mean(DC) -RMSFig. 9. The results of wavelet transrorm implemented in the virtual instrument.(Channel A analyzing sine signal and Channel B analyzing a chirp signal). Frequency Domain Aalysis: The plot of Magnitude vs. frequency, Phase vs. frequency and the facility to choose the windowing function.STFT based Joint Time Frequency Analysis (JTFA): The spectrogram with the additional choices of the plotting the graph with scale in decibels, windowing functions and the window length for STFT analysis.Wavelet based Joint Time Frequency Analysis(JTFA)：The scalogram which plots scales vs. time steps, choice of time-frequency sampling parameters like time steps and scales and the choice of wavelet functions.For the frequency domain analysis, DSP toolkit available with LabVIEW softwarewas utilized. Standard functions are available in the toolkit. The virtual instrument thus developed is intelligent as it takes different actions with different signals contrary to a digital storage oscilloscope. Trigger implemented enables us to obtian the correct value of the time period and a stable display. Analysis of complex signals can also be performed using this instrument. Fig.8 shows the front Panel of the virtual instrument showing Time-domain measurements. Fig.9 shows the time frequency relationship on both the channel B analyses the chirp signal. As seen clearly the chirp signal shows the varying frequency with time.5. Limitations of developed virtual instrumentSamples for few cycles are required to determin the triggering interval. One need to optimize tbe appropriate sampling rate and the number of samples to be processed. The processing time taken by the WHD technique is directly proportional to the number of samples and hence to the sampling rate as the higher sampling rate leads to the more number of samples per cycle. The time required to compute trigger also depends upon the speed of the computing system. For large amount of data (if high sampling rates us fixed), computationally heavy WHD algorithm and other features for more analysis, the butter might overflow leading to loss of data. Every time the input waveform is changed user has to do retriggering.6. Conclusion and discussionSuccessful development of the virtual instrument with the capability of acquiring, displaying and analyzing complex signals is done. The instrument over comes the shortcomings of the DSOs, found commonly in laboratories, in achieving stable display for complex signals. The developd instrument is cost effective and flexible in nature and had the large number of features to choose from. The computer towards the measurement systems. The VI developed is expected to go a long way in the instrumentation area.基于混合信号的数据采集卡的虚拟示波器摘要：复杂的信号在声纳、雷达、回声定位系统和谐振频率的研究中有多种应用。