电子束纵向磁聚焦的计算机模拟

给出了用VB模拟电子束纵向磁聚焦的绘图子程序。     

弹丸参数测试系统的数据处理

弹丸参数测试系统主要用于弹速度的测量,它可以测量弹丸速度的大小。弹丸速度的大小是弹道特性的重要参数之一。弹丸的速度测量是枪炮、弹药研制生产和开发验收中最基本的试验项目。天幕靶可以更快、更准确地测量弹速。基于天幕靶并利用Visual C++6.0开发了一款弹参数测试系统软件,可实现弹参数测试系统的数据处理。     

A novel area measurement scheme based on a multi-resolution dynamic contour

A novel scheme for an object's surface area measurement is proposed, which is suitable for area computation of an object with smooth and irregular edges. A multi-resolution dynamic contour is applied and this scheme consists of four steps. Firstly, a photoelectric image collimation system is applied to obtain a target image of a detected object. An image pyramid for the target image is constructed by wavelet decomposition and reconstruction. Secondly, in the image pyramid, a multi-resolution dynamic contour converges to the target's contour edge from coarse to fine scale, via feature search and an iteration algorithm. Thirdly, for the convergent dynamic contour, two formulas for the area and centroid computation of a closed B-spline curve are applied to compute the image target's area and centroid exactly. Finally, a novel centroid self-calibration technology is applied, which measures the pixel's size equivalence with the computed centroid and a dual-frequency laser to measure the true object's surface area exactly. Experiments indicate that this scheme's single-measurement error decreases to ±0.2%, when the number of control points is 20. Compared to conventional measurement approaches, this scheme is robust for a target image with noises or complicated edges.     

Retinotopic mapping with spin echo BOLD at 7T

For blood oxygenation level-dependent (BOLD) functional MRI experiments, contrast-to-noise ratio (CNR) increases with increasing field strength for both gradient echo (GE) and spin echo (SE) BOLD techniques. However, susceptibility artifacts and nonuniform coil sensitivity profiles complicate large field-of-view fMRI experiments (e.g., experiments covering multiple visual areas instead of focusing on a single cortical region). Here, we use SE BOLD to acquire retinotopic mapping data in early visual areas, testing the feasibility of SE BOLD experiments spanning multiple cortical areas at 7T. We also use a recently developed method for normalizing signal intensity in T₁-weighted anatomical images to enable automated segmentation of the cortical gray matter for scans acquired at 7T with either surface or volume coils. We find that the CNR of the 7T GE data (average single-voxel, single-scan stimulus coherence: 0.41) is almost twice that of the 3T GE BOLD data (average coherence: 0.25), with the CNR of the SE BOLD data (average coherence: 0.23) comparable to that of the 3T GE data. Repeated measurements in individual subjects find that maps acquired with 1.8-mm resolution at 3T and 7T with GE BOLD and at 7T with SE BOLD show no systematic differences in either the area or the boundary locations for V1, V2 and V3, demonstrating the feasibility of high-resolution SE BOLD experiments with good sensitivity throughout multiple visual areas.     

Relationship between neural and hemodynamic signals during spontaneous activity studied with temporal kernel CCA

Functional magnetic resonance imaging (fMRI) based on the so-called blood oxygen level-dependent (BOLD) contrast is a powerful tool for studying brain function not only locally but also on the large scale. Most studies assume a simple relationship between neural and BOLD activity, in spite of the fact that it is important to elucidate how the “when” and “what” components of neural activity are correlated to the “where” of fMRI data. Here we conducted simultaneous recordings of neural and BOLD signal fluctuations in primary visual (V1) cortex of anesthetized monkeys. We explored the neurovascular relationship during periods of spontaneous activity by using temporal kernel canonical correlation analysis (tkCCA). tkCCA is a multivariate method that can take into account any features in the signals that univariate analysis cannot. The method detects filters in voxel space (for fMRI data) and in frequency–time space (for neural data) that maximize the neurovascular correlation without any assumption of a hemodynamic response function (HRF). Our results showed a positive neurovascular coupling with a lag of 4–5 s and a larger contribution from local field potentials (LFPs) in the γ range than from low-frequency LFPs or spiking activity. The method also detected a higher correlation around the recording site in the concurrent spatial map, even though the pattern covered most of the occipital part of V1. These results are consistent with those of previous studies and represent the first multivariate analysis of intracranial electrophysiology and high-resolution fMRI.     

Adsorption of Basic Dyes Using Walnut Shell-based Biochar Produced by Hydrothermal Carbonization

Hydrothermal carbon(HC) was prepared from walnut shells, which are abundant in Northeastern China. The prepared HC was used as a precursor to produce nitric acid modified carbon(MC). The hydrothermal carbonization included dehydration and decarboxylation processes wherein the hemicellulose was completely decomposed and the cellulose was partly decomposed, with some oxygen-containing functional groups being produced. The aromati-city, specific surface area and pore content of the HC increased, but its polarity decreased. With 6 mol/L nitric acid and a modification time of 15 min, the specific surface area and pore content decreased, but the proportion of oxygen-containing functional groups on the surface increased significantly, thereby improving the dye adsorption performance. The adsorption of methylene blue and malachite green was best described by the pseudo-second-order kinetic and Langmuir isotherm models. The adsorption capacity of MC was determined to be much larger than that of HC.     

碱性二苯基萘基甲烷染料褪色分光光度法测定藻酸钠

在B-R缓冲溶液中,藻酸钠与维多利亚蓝4R、维多利亚蓝B、夜蓝等碱性二苯基萘基甲烷染料发生反应,形成结合产物,染料发生明显的褪色.对于不同染料,最大褪色波长分别位于612 nm(维多利亚蓝4R体系)、616 nm(维多利亚蓝B体系)、614 nm(夜蓝体系).体系吸光度的降低与藻酸钠的质量浓度成正比.藻酸钠的质量浓度在5.0 mg·L-1(维多利亚蓝4R体系)、3.0 mg·L-1(维多利亚蓝B体系)、3.0 mg·L-1(夜蓝体系)以内符合比耳定律,摩尔吸光率根据染料的不同在4.8×106～9.5×106 L·mol-1·cm-1之间,其中以维多利亚蓝4R体系最为灵敏,对藻酸钠的检出限为21 μg·L-1.以维多利亚蓝4R体系为例研究共存物质的影响,表明方法选择性好.此法用于面条样品中藻酸钠的分析测定,结果满意.     

固相络合萃取脱除柴油中碱性氮化物的工艺及模型研究

应用自行合成的分离材料对固相络合萃取脱除柴油中碱性氮化合物进行了研究。测定了不同条件下柴油在合成树脂柱中的穿透曲线和洗脱曲线,实验测得动态吸附容量达到了7.85mg/gwetresin,碱性氮的脱除率达到了91%。表明本法具有树脂吸附容量大,碱性氮或收率高的特点;同时利用二阶动力学推动力模型描述固定床动态过程,考察了轴向返混对穿透曲线的影响,模型计算值与实验数据符合较好。     

基础化学实验中开展线上线下混合式教学的探索与实践

为了提高基础化学实验课程的教学质量、探索实验教学新模式,建设了基本操作微视频和实验讲座微视频等线上教学资源,开发了线上考试系统和线上数据提交及评分系统,创建了"ZJU化学实验教学中心"微信公众号,开展了线上线下混合式教学,取得了较好的教学效果,为高校化学实验课程的教学改革提供一些参考。     

传统铜化合物制备实验教学的重新设计

如何结合新时代大学生核心素养培养,特别是化学学科核心素养内涵的新要求,对传统基础无机化学实验进行重新设计与改进显得十分必要。在本论文中,我们以传统的铜盐制备实验为基础,重新设计了一个包括产物合成、性质鉴定及成分分析在内的综合性实验。该实验以碱式碳酸铜为原料,合成了两种化合物：醋酸铜与氟硼酸二(N,N-二乙基乙二胺)合铜。通过这两种化合物的对比制备,加深学生对无机盐合成方法,特别是其中涉及的结晶过程理解,夯实其基本实验技能。同时,利用化合物的颜色变化,特别是配合物热致变色实验,强化他们对晶体场理论的认识。此外,将碘量法这一传统滴定分析方法,融入原料碱式碳酸铜的组成分析中,使该实验成为一个集无机与分析于一体的综合实验。上述改进将有利于培养学生科研思维与创新能力,特别适合低年级本科生开设(8学时)。