一种基于三角数分解的可配置2-D卷积器优化方法

多尺寸2-D卷积通过特征提取在检测、分类等计算机视觉任务中发挥着重要作用。然而,目前缺少一种高效的可配置2-D卷积器设计方法,这限制了卷积神经网络(CNN)模型在边缘端的部署和应用。该文基于乘法管理以及奇平方数的三角数分解方法,提出一种高性能、高适应性的卷积核尺寸可配置的2-D卷积器。所提2-D卷积器包含一定数量的处理单元(PE)以及相应的控制单元,前者负责运算任务,后者负责管理乘法运算的组合,二者结合以实现不同尺寸的卷积。具体地,首先根据应用场景确定一个奇数列表,列表中为2-D卷积器所支持的尺寸,并利用三角数分解得到对应的三角数列表;其次,根据三角数列表和计算需求,确定PE的总数量;最后,基于以小凑大的方法,确定PE的互连方式,完成电路设计。该可配置2-D卷积器通过Verilog硬件描述语言(HDL)设计实现,由Vivado 2 022.2在XCZU7EG板卡上进行仿真和分析。实验结果表明,相比同类方法,该文所提可配置2-D卷积器,乘法资源利用率得到显著提升,由20%~50%提升至89%,并以514个逻辑单元实现1 500 MB/s的吞吐率,具有广泛的适用性。

2-D Modeling and Calculations of Stratospheric Ozone and Influences of Convection, Diffusion, and Time

An engineering system approach of 2-D cylindrical model of transient mass balance calculations of ozone and other concerned chemicals along with fourteen photolysis, ozone-generating and ozone-depleting chemical reaction equations was developed, validated, and used for studying the ozone concentrations, distribution and peak of the layer, ozone depletion and total ozone abundance in the stratosphere. The calculated ozone concentrations and profile at both the Equator and a 60˚N location were found to follow closely with the measured data. The calculated average ozone concentration was within 1% of the measured average, and the deviation of ozone profiles was within 14%. The monthly evolution of stratospheric ozone concentrations and distribution above the Equator was studied with results discussed in details. The influences of slow air movement in both altitudinal and radial directions on ozone concentrations and profile in the stratosphere were explored and discussed. Parametric studies of the influences of gas diffusivities of ozone DO3 and active atomic oxygen DO on ozone concentrations and distributions were also studied and delineated. Having both influences through physical diffusion and chemical reactions, the diffusivity (and diffusion) of atomic oxygen DO was found to be more sensitive and important than that of ozone DO3 on ozone concentrations and distribution. The 2-D ozone model present in this paper for stratospheric ozone and its layer and depletion is shown to be robust, convenient, efficient, and executable for analyzing the complex ozone phenomena in the stratosphere. .

Surface characteristics analysis of fractures induced by supercritical CO_(2)and water through three-dimensional scanning and scanning electron micrography

Morphology of hydraulic fracture surface has significant effects on oil and gas flow,proppant migration and fracture closure,which plays an important role in oil and gas fracturing stimulation.In this paper,we analyzed the fracture surface characteristics induced by supercritical carbon dioxide(SC-CO_(2))and water in open-hole and perforation completion conditions under triaxial stresses.A simple calculation method was proposed to quantitatively analyze the fracture surface area and roughness in macro-level based on three-dimensional(3D)scanning data.In micro-level,scanning electron micrograph(SEM)was used to analyze the features of fracture surface.The results showed that the surface area of the induced fracture increases with perforation angle for both SC-CO_(2)and water fracturing,and the surface area of SC-CO_(2)-induced fracture is 6.49%e58.57%larger than that of water-induced fracture.The fractal dimension and surface roughness of water-induced fractures increase with the increase in perforation angle,while those of SC-CO_(2)-induced fractures decrease with the increasing perforation angle.A considerable number of microcracks and particle peeling pits can be observed on SC-CO_(2)-induced fracture surface while there are more flat particle surfaces in water-induced fracture surface through SEM images,indicating that fractures tend to propagate along the boundary of the particle for SC-CO_(2)fracturing while water-induced fractures prefer to cut through particles.These findings are of great significance for analyzing fracture mechanism and evaluating fracturing stimulation performance.

基于CT扫描的CO_(2)相变致裂煤裂隙演化特征

为进一步揭示CO_(2)相变致裂煤的裂隙改造机理,开展了CO_(2)相变致裂煤体实验,基于CT扫描和三维裂隙重构,分析了CO_(2)相变致裂前后的煤样内部裂隙结构参数,查明了CO_(2)相变致裂煤的三维裂隙结构演化特征。结果表明,致裂后煤样的裂隙总数量减少,裂隙总体积和裂隙总表面积增加;CO_(2)相变致裂产生了裂隙扩张转化效应,在致裂压力的扩张作用下,小尺度裂隙转化为更大尺度的裂隙;长度小于1000μm的裂隙数量减少、裂隙体积和表面积明显减小,长度大于1000μm的裂隙体积和表面积明显增大,且裂隙之间扩张贯通而引起其数量减少;CO_(2)相变致裂大幅度改善了煤体三维裂隙的连通性,有利于气体的运移和产出。此研究为CO_(2)相变致裂效果提供新的分析评价方法,也可为其他非常规天然气储层及其改造的裂隙演化特征研究提供参考和借鉴。

基2-FFT输入分级截断算法在频域合成孔径超声成像中的研究

为提高超声频域成像算法的计算速度,提出一种应用于超声频域成像算法的基2-FFT输入分级截断算法。首先,借助于COMSOL多物理场仿真软件,建立钢件中含有孔缝缺陷的有限元模型进行声场仿真。仿真结果得到关于缺陷的回波信号,并通过PSM算法对频域内声场进行重建,得到成像区域的聚焦图像,和原始仿真信号的B扫图像相比效果更加直观且成像质量更好,验证了PSM算法的可行性。然后为了避免超声频域成像算法中二维傅里叶变换的冗余计算,进一步提出了支持任意非0值输入的基2-FFT输入分级截断算法。实验结果证明,基2-FFT输入分级截断算法比标准基2-FFT算法快27%,超声频域算法成像速度提高13%。

An assessment of arctic sea ice concentration retrieval based on “HY-2” scanning radiometer data using field observations during CHINARE-2012 and other satellite instruments

A retrieval algorithm of arctic sea ice concentration （SIC） based on the brightness temperature data of “HY-2” scanning microwave radiometer has been constructed. The tie points of the brightness temperature were selected based on the statistical analysis of a polarization gradient ratio and a spectral gradient ratio over open water （OW）, first-year ice （FYI）, and multiyear ice （MYI） in arctic. The thresholds from two weather filters were used to reduce atmospheric effects over the open ocean. SIC retrievals from the “HY-2” radiom-eter data for idealized OW, FYI, and MYI agreed well with theoretical values. The 2012 annual SIC was calcu-lated and compared with two reference operational products from the National Snow and Ice Data Center （NSIDC） and the University of Bremen. The total ice-covered area yielded by the “HY-2” SIC was consistent with the results from the reference products. The assessment of SIC with the aerial photography from the fifth Chinese national arctic research expedition （CHINARE） and six synthetic aperture radar （SAR） images from the National Ice Service was carried out. The “HY-2” SIC product was 16% higher than the values de-rived from the aerial photography in the central arctic. The root-mean-square （RMS） values of SIC between “HY-2” and SAR were comparable with those between the reference products and SAR, varying from 8.57% to 12.34%. The “HY-2” SIC is a promising product that can be used for operational services.

A preliminary assessment of the sea surface wind speed production of HY-2 scanning microwave radiometer

A scanning microwave radiometer（RM） was launched on August 16,2011,on board HY-2 satellite.The six-month long global sea surface wind speeds observed by the HY-2 scanning microwave radiometer are preliminarily validated using in-situ measurements and WindSat observations,respectively,from January to June 2012.The wind speed root-mean-square（RMS） difference of the comparisons with in-situ data is 1.89 m/s for the measurements of NDBC and 1.72 m/s for the recent four-month data measured by PY30-1 oil platform,respectively.On a global scale,the wind speeds of HY-2 RM are compared with the sea surface wind speeds derived from WindSat,the RMS difference of 1.85 m/s for HY-2 RM collocated observations data set is calculated in the same period as above.With analyzing the global map of a mean difference between HY-2 RM and WindSat,it appears that the bias of the sea surface wind speed is obviously higher in the inshore regions.In the open sea,there is a relatively higher positive bias in the mid-latitude regions due to the overestimation of wind speed observations,while the wind speeds are underestimated in the Southern Ocean by HY-2 RM relative to WindSat observations.

Possible Nodeless Superconducting Gaps in Bi_2Sr_2CaCu_2O_(8+δ) and YBa_2Cu_3O_(7-x) Revealed by Cross-Sectional Scanning Tunneling Spectroscopy

Pairing in the cuprate high-temperature superconductors and its origin remain among the most enduring mysteries in condensed matter physics. With cross-sectional scanning tunneling microscopy/spectroscopy, we clearly reveal the spatial-dependence or inhomogeneity of the superconducting gap structure of Bi2Sr2CaCu2O8＋δ （Bi2212） and YBa2Cu3O7-x （YBCO） along their c-axes on a scale shorter than the interlayer spacing. By tunneling into the （100） plane of a Bi2212 single crystal and a YBCO film, we observe both U-shaped tunneling spectra with extended fiat zero-conductance bottoms, and V-shaped gap structures, in different regions of each sample. On the YBCO film, tunneling into a （110） surface only reveals a U-shaped gap without any zero-bias peak. Our analysis suggests that the U-shaped gap is likely a nodeless superconducting gap. The V-shaped gap has a very small amplitude, and is likely proximity-induced by regions having the larger U-shaped gap.

一种高速2-D滑动FFT的设计实现

文章介绍了采用2-D快速傅里叶变换(fast Fourier transform,FFT)算法的滑动窗FFT的基本特性原理和硬件实现过程,完成了窗长256点、步长16点的2-D滑动窗FFT的专用集成电路(application specific integrated circuit,ASIC)设计。传统FFT算法受序列完整性的制约,时滞较大,无法满足某些高实时性信号分析领域的处理速度要求。该文采用滑动FFT算法,克服了传统FFT对序列完整性的依赖,设计的滑动FFT处理器使用2-D FFT压缩新序列计算时间,以基16蝶形运算器为核心,采用系数复用和高基Booth方法优化系数编码技术压缩乘法器的数量,减少电路面积。所设计的2-D滑动FFT完成单次滑动窗长的计算时间比传统算法节约了16.1%,变换结果与MATLAB的运算结果相比,信噪比(signal-to-noise ratio,SNR)大于130 dB。在TSMC 28 nm的工艺下,工作主频为600 MHz,面积为1980μm×2060μm。

Reformatted method for two-dimensional detector arrays measurement data in proton pencil beam scanning

The spatial resolution of a commercial two-dimensional(2D)ionization chamber(IC)array is limited by the size of the individual detector and the center-to-center distance between sensors.For dose distributions with areas of steep dose gradients,inter-detector dose values are derived by the interpolation of nearby detector readings in the conventional mathematical interpolation of 2D IC array measurements.This may introduce significant errors,particularly in proton spot scanning radiotherapy.In this study,by combining logfile-based reconstructed dose values and detector measurements with the Laplacian pyramid image blending method,a novel method is proposed to obtain a reformatted dose distribution that provides an improved estimation of the delivered dose distribution with high spatial resolution.Meanwhile,the similarity between the measured original data and the downsampled logfilebased reconstructed dose is regarded as the confidence of the reformatted dose distribution.Furthermore,we quantify the performance benefits of this new approach by directly comparing the reformatted dose distributions with 2D IC array detector mathematically interpolated measurements and original low-resolution measurements.The result shows that this new method is better than the mathematical interpolation and achieves gamma pass rates similar to those of the original low-resolution measurements.The reformatted dose distributions generally yield a confidence exceeding 95%.

2-D distributed pose estimation of multi-agent systems using bearing measurements

This article studies distributed pose(orientation and position)estimation of leader–follower multi-agent systems over𝜅-layer graphs in 2-D plane.Only the leaders have access to their orientations and positions,while the followers can measure the relative bearings or(angular and linear)velocities in their unknown local coordinate frames.For the orientation estimation,the local relative bearings are used to obtain the relative orientations among the agents,based on which a distributed orientation estimation algorithm is proposed for each follower to estimate its orientation.For the position estimation,the local relative bearings are used to obtain the position constraints among the agents,and a distributed position estimation algorithm is proposed for each follower to estimate its position by solving its position constraints.Both the orientation and position estimation errors converge to zero asymptotically.A simulation example is given to verify the theoretical results.

具有执行器饱和的切换2-D系统事件触发控制

针对具有执行器饱和的切换2-D连续离散系统,提出了一种基于多Lyapunov函数法的事件触发控制方案;为了减少通信资源浪费和执行器的损耗,提出了一种事件触发机制;该触发机制考虑了执行器饱和特性,只有当执行器未饱和,且满足事件触发条件时,控制器才会更新;利用凸组合技术和多Lyapunov函数法,提出了一种状态依赖的切换信号与状态反馈控制器的设计方法,并对闭环系统的指数稳定性进行了分析,利用线性矩阵不等式技术导出了控制器增益矩阵存在的充分条件;利用Darboux方程的仿真算例验证了所提出的事件触发控制方案的有效性,仿真结果表明了在所设计的控制方案下,闭环系统的状态是指数收敛的,同时还能减少通信资源的浪费。

“探究2,4-D对插枝生根的作用”实验中因变量的确定

“探究2,4-D对插枝生根的作用”是浙科版高中生物学教材选择性必修1教材中的重要实验,实践中一些师生对该实验中的因变量常有疑惑,本文选择常见的碰碰香作为实验材料展开探究。发现2,4-D浓度在2.5×10-4—2.5×10-14g/L浓度范围内,对根的平均长度和根的总长度作用差异不明显,但是对根的数量有显著的差异。该探究可为师生提供一定的参考。

CO_(2)激光退火不同外径锗芯光纤的扫描速度研究

对内径为41~43μm,外径约为188μm、251μm和270μm的锗芯光纤进行激光退火实验,研究CO_(2)激光沿光纤轴向扫描速度对锗芯拉曼峰频率和光传输损耗特性的影响。研究发现,激光扫描速度是决定退火后光纤特性的重要参数。对不同外径的光纤,达到最优退火效果的激光扫描速度不同,188μm、251μm和270μm外径的锗芯光纤分别为10 mm·s^(-1)、14 mm·s^(-1)和16 mm·s^(-1),光传输损耗分别为3.435 dB·cm^(-1)、2.147 dB·cm^(-1)和3.578 dB·cm^(-1)。使用COMSOL软件对退火过程中纤芯表面固定点的温度变化进行了模拟仿真研究,仿真结果显示激光退火过程中温度呈脉冲形变化。相同外径条件下,激光扫描速度提高,温度脉冲的峰值升高、谷值降低、单脉冲持续时间缩短;相同扫描速度条件下,光纤外径减小,温度脉冲峰值提高,谷值降低。

基于多重扫描速率法的α-Al_(2)O_(3)煅烧动力学研究

以氢氧化铝粉体为原料,探究氢氧化铝煅烧为α-Al_(2)O_(3)过程中的相转变与微观组织变化,利用多重扫描速率法对其煅烧过程进行动力学模拟计算。结果表明,氢氧化铝煅烧为α-Al_(2)O_(3)的优化条件为:煅烧温度1200℃、煅烧时间2 h、升温速率5℃/min。氢氧化铝煅烧过程出现3个吸热峰,对应3个失重阶段:第一阶段反应机理函数为G(α)=[(1-α)^(-1/3)-1]^2,反应平均活化能为91.16 kJ/mol,指前因子17.00×10^(9)~44.03×10^(9)min^(-1);第二阶段反应机理函数为G(α)=α~2,反应平均活化能为106.2 kJ/mol,指前因子7.70×10^(9)~18.60×10^(9)min^(-1);第三阶段反应机理函数为G(α)=α~(1/4),反应平均活化能为235.42 kJ/mol,指前因子39.94×10^(9)~50.79×10^(9)min^(-1)。

Growth and characterization of Bi(110)/CrTe_(2) heterostructures:Exploring interplay between magnetism and topology

The interplay between topology and magnetism is vital for realizing exotic quantum phenomena,significant examples including quantum anomalous Hall effect,axion insulators,and high-order topological states.These states host great potential for future applications in high-speed and low-consumption electronic devices.Despite being extensively investigated,practical platforms are still scarce.In this work,with molecular beam epitaxy(MBE),we provide the first experimental report on high-quality Bi(110)/CrTe_(2) magnetic heterostructure.By employing in-situ high-resolution scanning tunneling microscopy,we are able to examine the interaction between magnetism and topology.There is a potential edge state at an energy level above the Fermi level,but no edge states observed near the Fermi level The absence of high-order topological corner states near EF highlights the importance of lattice matching and interface engineering in designing high-order topological states.Our study provides key insights into the interplay between two-dimensional magnetic and topological materials and offers an important dimension for engineering magnetic topological states.

Microscopic growth mechanism and edge states of monolayer 1T'-MoTe_(2)

Transition metal ditellurides(TMTDs)have versatile physical properties,including non-trivial topology,Weyl semimetal states and unique spin texture.Controlled growth of high-quality and large-scale monolayer TMTDs with preferred crystal phases is crucial for their applications.Here,we demonstrate the epitaxial growth of 1T'-MoTe_(2) on Au(111)and graphitized silicon carbide(Gr/SiC)by molecular beam epitaxy(MBE).We investigate the morphology of the grown1T'-MoTe_(2) at the atomic level by scanning tunnelling microscopy(STM)and reveal the corresponding microscopic growth mechanism.It is found that the unique ordered Te structures preferentially deposited on Au(111)regulate the growth of monolayer single crystal 1T'-MoTe_(2),while the Mo clusters were preferentially deposited on the Gr/SiC substrate,which impedes the ordered growth of monolayer MoTe_(2).We confirm that the size of single crystal 1T'-MoTe_(2) grown on Au(111)is nearly two orders of magnitude larger than that on Gr/SiC.By scanning tunnelling spectroscopy(STS),we observe that the STS spectrum of the monolayer 1T'-MoTe_(2) nano-island at the edge is different from that at the interior,which exhibits enhanced conductivity.

Image charge effect on the light emission of rutile TiO2(110) induced by a scanning tunneling microscope

The plasmon-enhanced light emission of rutile TiO2（110） surface has been investigated by a low-temperature scanning tunneling microscope （STM）. We found that the photon emission arises from the inelastic electron tunneling between the STM tip and the conduction band or defect states of TiO2（110）. In contrast to the Au（111） surface, the maximum photon energy as a function of the bias voltage clearly deviates from the linear scaling behavior, suggesting the non-negligible effect of the STM tip on the band structure of TiO2. By performing differential conductance （dl/dV） measurements, it was revealed that such a deviation is not related to the tip-induced band bending, but is attributed to the image charge effect of the metal tip, which significantly shifts the band edges of the TiO2（110） towards the Femi level （EF） during the tunneling process. This work not only sheds new lights onto the understanding of plasmon-enhanced light emission of semiconductor surfaces, but also opens up a new avenue for engineering the plasmon-mediated interfacial charge transfer in molecular and semiconducting materials.

Calculations and Sensitivity Analysis of Chlorine-,NO_(x)-,and Bromine-Depleting Cycles of Stratospheric Ozone

This paper presents an engineering system approach using a 2D model of conservation of mass to study the dynamics of ozone and concerned chemical species in the stratosphere.By considering all fourteen photolysis,ozone-generating,and-depleting chemical reactions,the model calculated the transient,spatial changes of ozone under different physical-chemical-radiative conditions.Validation against the measured data demonstrated good accuracy,close match of our model with the observed ozone concentrations at both 20°S and 90°N locations.The deviation in the average concentration was less than 1% and in ozone profiles less than 17%.The impacts of various chlorine-(Cl),nitrogen oxides-(NO_(x)),and bromine-(Br)depleting cycles on ozone concentrations and distribution were investigated.The chlorine catalytic depleting cycle was found to exhibit the most significant impact on ozone dynamics,confirming the key role of chlorine in the problem of ozone depletion.Sensitivity analysis was conducted with levels of 25%,50%,100%,200%,and 400% of the baseline value.The combined cycles(Cl+NO_(x)+Br)showed the most significant influence on ozone behavior.The total ozone abundance above the South Pole could decrease by a small 3%,from 281 DU(Dubson Units)to 273 DU for the 25% level,or by a huge thinning of 60%to 114 DU for the 400% concentration level.When the level of chlorine gases increased beyond 200%,it would cause ozone depletion to a level of ozone hole(below 220 DU).The 2D Ozone Model presented in this paper demonstrates robustness,convenience,efficiency,and executability for analyzing complex ozone phenomena in the stratosphere.

封闭空间煤心固碳过程CO_(2)吸附-运移特征

煤储层注CO_(2)过程中,CO_(2)的扩散和吸附进展缓慢,不同注气压力下吸附-运移时效特征对设计煤层封存CO_(2)具有重要影响。因此,采用双能X射线CT扫描,并计算分析了煤储层在围压下注气前后煤心密度变化和CO_(2)浓度。研究结果表明:在煤心的不同区域,气体以不同的速度运移,扩散和吸附进展缓慢;煤心中平均CO_(2)浓度随时间和CO_(2)注入压力的增加而增加,CO_(2)浓度从注气端向出口段沿煤心轴向几乎单调下降;煤心中CO_(2)浓度分布不均匀,煤心密度较高区域CO_(2)浓度越低(矿物质影响),煤基质密度较小处CO_(2)浓度越高。