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ShapeMemoryAlloy_TrainingTutorial

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Shape Memory Alloy

Shape Training

Tutorial

A Teacher’s Guide To Teaching SMA Shape Training

The Reaction Figures (Team 3) Lisa Case Zachary Kreiner John Redmond Brian Trease

ME559 – Smart Materials and Structures Fall 2004

Thursday, December 9, 2004

1. ABSTRACT..........................................................................................................................................................................3

2. TUTORIAL PURPOSE AND EDUCATIONAL OUTCOMES.......................................................................................3

2.1. EDUCATIONAL OBJECTIVES...........................................................................................................................................3

3. LEADER GUIDE.................................................................................................................................................................4

3.1. SAFETY ISSUES.............................................................................................................................................................4 3.2. HEATING METHODS......................................................................................................................................................4 3.3. MATERIALS...................................................................................................................................................................5 3.3.1. In-class Lab............................................................................................................................................................5 3.3.2. Homework Lab.......................................................................................................................................................7 3.4. PROCEDURE..................................................................................................................................................................7 3.4.1. In-Class Workshop.................................................................................................................................................8 3.4.1.1 Walk-through Example................................................................................................................................8 3.4.1.2 Fixturing......................................................................................................................................................8 3.4.1.3 Heat Treatment..........................................................................................................................................10 3.4.1.4 Talking Points............................................................................................................................................11 3.4.2. Transformation Temperature...............................................................................................................................13 3.4.3. Homework Lab.....................................................................................................................................................14 3.5. GRADING....................................................................................................................................................................15 3.5.1. Grading the Basics...............................................................................................................................................15 3.5.2. Grading the In-class Lab......................................................................................................................................16 3.5.3. Grading the Homework Lab.................................................................................................................................16

4. VALIDATION....................................................................................................................................................................18

5. CONCLUSIONS................................................................................................................................................................19

6. REFERENCES...................................................................................................................................................................20

7. APPENDIX.........................................................................................................................................................................21

7.1. PRE-LAB READING......................................................................................................................................................22 7.2. PRE-LAB QUESTIONNAIRE...........................................................................................................................................28 7.3. IN-CLASS WORKSHOP INSTRUCTIONS..........................................................................................................................29 7.4. IN-CLASS WORKSHOP SUPPLEMENTAL INFORMATION.................................................................................................32 7.5. IN-CLASS WORKSHOP QUESTIONS...............................................................................................................................33 7.6. HOMEWORK LAB INSTRUCTIONS.................................................................................................................................34 7.7. HOMEWORK LAB QUESTIONS......................................................................................................................................437.8. GRADE SHEET.............................................................................................................................................................447.9. LAB EVALUATION.......................................................................................................................................................45 7.10. SUPPLEMENTAL FIGURES............................................................................................................................................46

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The Properties of Shape Memory Alloys

The Properties of Shape Memory Alloys

The Properties of Shape Memory Alloys

Shape memory alloys, or SMAs, are a class of materials that not only exhibit

remarkable mechanical properties, such as high strength and ductility, but also have the

ability to return to their original shape after being deformed. This unique property is

achieved due to a reversible phase transformation that occurs upon heating and cooling

the alloy. The discovery of SMAs over half a century ago has led to a wide range of

practical applications in various fields, including aerospace, biomedical, and robotics. In

this article, we will explore the properties of SMAs and their potential uses.

Shape memory alloys are typically made from a combination of metals, such as

nickel and titanium, which are alloyed together in specific proportions. The resulting

material has two distinct phases, depending on the temperature: austenite and martensite.

基于前视三维声呐的轨条砦识别方法

基于前视三维声呐的轨条砦识别方法

基于前视三维声呐的轨条砦识别方法

李宝奇;任露露;陈发;钱斌;黄海宁

【期刊名称】《水下无人系统学报》

【年(卷),期】2022(30)6

【摘 要】针对轨条砦目标探测和识别困难的问题,文中利用前视三维成像声呐提高轨条砦目标探测效果,并设计一种基于单步检测(SSD)的三维点云目标识别方法(PCSSD)。该方法首先对原始波束域数据进行阈值滤波和直通滤波处理;接着,对滤波后的三维点云数据进行前向投影,并得到深度灰度图和深度伪彩图;而后,利用SSD目标检测模型对深度伪彩图进行检测识别;随后,从深度灰度图检测目标特征中计算目标的深度范围;最后,结合二维目标检测结果和深度范围对三维点云中的轨条砦目标进行标注。与此同时,提出了一个基于多尺度注意力机制的特征提取模块,并利用该模块设计了改进的目标检测模型SSD-MV3ME。在三维点云轨条砦目标检测数据集GTZ上,SSD-MV3ME在检测时间基本相等的条件下,检测精度比轻量化目标检测模型SSD-MV3提升1.05%,模型参数减少2482 KB。实验结果表明,基于SSD-MV3ME的PCSSD更适合轨条砦目标识别任务。

【总页数】7页(P747-753)

【作 者】李宝奇;任露露;陈发;钱斌;黄海宁

【作者单位】中国科学院声学研究所;苏州桑泰海洋仪器研发有限责任公司;中国科学院大学;中国科学院先进水下信息技术重点实验室

【正文语种】中 文 【中图分类】TJ630.1;U644

【相关文献】

1.基于三维模型的前视红外目标匹配识别方法2.应用二维稀疏阵列的三维前视声呐方位估计3.基于Khatri-Rao积的三维前视声呐空间方位估计技术4.三维前视声呐信号处理方法5.大噪声环境下前视声呐图像目标识别方法研究

因版权原因，仅展示原文概要，查看原文内容请购买

动手学深度学习第二版

动手学深度学习第二版

1.一种简单的风格迁移方法

(1) 初始化合成图像，例如将其初始化为内容图像(content image)；

(2) 利用预训练网络（如VGG-19）的某些层抽取内容图像与合成图像的内容特征，再用某些层抽取风格图像与合成图像的风格特征；

(3) 根据抽取出来的content feature map和style feature map计算出内容损失（content loss，使合成图像与内容图像在内容特征上接近）和风格损失（style loss，使合成图像与风格图像在风格特征上接近）；

(4) 根据当前的合成图像自身计算出全变分损失（total variation loss，有助于减少合成图像中的噪点）；

(5) 将这三个损失按一定比例加权（主观更倾向于合成什么样的图像），计算出最终的总损失；

(6) 根据损失反向传播误差，逐步更新合成图像的参数，降低损失，最终结束训练，图像风格迁移成功。

The Mechanics of Shape Memory Alloys

The Mechanics of Shape Memory Alloys

The Mechanics of Shape Memory Alloys

形状记忆合金的机械学

形状记忆合金（Shape Memory Alloy，SMA）是一种特殊的合金，其能够在外力的刺激下，从一种形态恢复到另一种形态，然后在去除外力的情况下，又会重现原本的形状。通过这种独特的行为，SMA 已经成为了材料科学领域里的重要研究方向之一。在本文中，我们将着眼于 SMA 的机械学特性，以深入探讨这种合金的工程应用以及科学原理。

一、SMA 的特殊结构

首先，让我们来了解一下 SMA 的基本结构。SMA 是由两种或更多种金属合金成分组合而成的合金材料。在它们的结构中，存在特殊的“孪晶”结构，这是 SMA

的特性之一。此时每个孪晶体内部有两个晶胞，两个晶胞之间通过对称映射互相链接在一起。当这种结构被应变调整时，孪晶就会发生位移，随之内部形态发生变化。

二、形状记忆的机理

SMA 的形状记忆本质上是靠能储存应变能够改变自己形状。当一个 SMA 被加热时，它原来的形状会发生改变，因为 SMA 的“孪晶”结构被外界应力引起位移。当SMA 冷却时，它就会恢复到原来的形状，但是具体的形状回弹方式则取决于温度和应力等条件。在下面我们将简单地介绍形状记忆的基本机理。

1. 预应变

为了激活 SMA 的形状记忆效应，我们需要在其冷却之前对其进行预应变（Pre-Strain）。这种方法会使 SMA 的晶体结构发生变化，并留下应变能在冷却时产生形状记忆效应。

2. 相变 SMA 的形状记忆与相变（Phase transition）密切相关。相变是指 SMA 的结构从一种晶体结构转变为另一种晶体结构。比如，当我们将高锰钢（High Manganese

Steel）在高温下冷却到室温时，其晶体结构会从奥氏体（Austenite）转变为马氏体（Martensite），而形状记忆效应便是依靠这种相变操作实现的。

3. 热和应力