四维打印技术概述

四维打印技术是在三维打印技术的基础上增加一维时间元素,人们可以通过软件设定模型和时间,变形材料会在设定的时间内折叠为所需的形状。相对于三维打印技术,四维打印技术更加"智能",物料可自行组装,具有经济、高效、直接的优点。文章对这项新技术的相关名词、技术要点以及应用前景进行了简要介绍。     

四维打印

正在三维打印方兴未艾之际,"4D打印"概念已悄然跃入人们的视野。沿袭三维打印的命名方式,"4D打印"(four dimensional printing)应称为"四维打印"。四维打印是在三维打印的基础上增加了第四个维度——时间,通过软件设定模型和时间,让产品在相应的时间或随着环境的变化而自动变形成相应的形状。近日,麻省理工学院的一个科学家团队借助于3D打印技术,在打印之后对原有物体进行转化,生成了一种强度比钢强10倍而密度只有钢的1/20的新型轻质材料,让4D打印成为打印历史上又一里程碑。4D打印技术除了拥有3D     

增材制造——3D打印的正称

三维打印具有狭义和广义两种概念,广义上的三维打印在国内外学术界和政府文件里被称为增材制造。文章还介绍了增材制造技术相关的多种制造工艺。     

科研系统工程的"四维结构"与"四定分析"--以国家科技攻关305项目为例

技术方法的优选与组合在科研系统工程活动中具有重要意义，拟将通用的系统工程方法“霍尔三维结构”发展为科研系统工程“四维结构”，即增加第四维－技术维。对于具有强烈时空特处的复杂科研系统工程来说，仅采用定性与定量分析相结合的方法是不够的，应将其发展为定性－定量－定时－定位分析相结合的“四定分析综合集成法”。     

美国3D打印建筑物

正美国航天局(NASA)出资与美国南加州大学合作研发出"轮廓工艺"3D打印技术,该3D打印技术在24小时内就可以印出大约232平方米的两层楼房子。由于大大节约了建筑时间和建筑成本,该技术让人类在移民月球或火星后可以就地取材,快速并且批量打印出"外星屋"。     

3D技术、3D打印机的中文定名

近年来,3D电影、3D游戏、3D打印等高新技术深刻地改变着人们的生活方式和工作方式。3D技术的概念特指基于计算机及互联网的三维数字化技术。经过数十年的发展,3D技术在成熟度、易用度、经济性等方面都已经取得了巨大的突破,成为促进我国文化创意产业升级和自主创新的推动力。     

阵列激发极化野外采集系统研发

文章应用计算机网络技术、GPS技术实现阵列同步采集。应用伪随机、m序列码相关辨识技术提高抗干扰能力,通过同步一发多收的模式使激发极化法二维三维成像成为可能。     

植入式人工肝组织喷射成形制造技术

三维（3D）打印是当今科研界乃至商业界的一大热点，被认为是第三次工业革命或制造业的新突破点。人体器官打印已被当作概念股炒作上市，吸引了无数人的注意。但器官3D打印还处于刚刚起步阶段，尤其是复杂器官打印面临着巨大的困难和挑战，其中最主要的就是分支血管和神经系统的快速构建。清华大学机械系王小红老师负责的团队，2004年由“生物制造中心”更名为“器官制造中心”，在“植入式人工肝组织喷射成形制造技术”方面取得了一系列创新性成果，发表了Science Citation Index （SCI）收录的研究论文五十多篇。     

3D打印：社会化制造的新时代

3D打印（3D Printing）技术作为快速成型领域的一种新兴技术,目前正成为一股迅猛发展的潮流。文章从3D打印催生新一轮工业革命、3D打印在全球迅猛发展、3D打印与第三次工业革命的角度阐述了3D打印的发展进程,指出3D打印给中国制造业带来的机遇与挑战．     

特种纳米涂料

一、主要技术内容 "特种纳米涂料"系"九五"科技攻关成果项目. 纳米材料是由表面(界面)结构组元构成的材料,粒径介于原子团簌与常规粉体之间,一般不超过100纳米.一般根据纳米材料的不同需要,控制其粒子的形态就形成了以下三种纳米材料三维尺寸均为纳米量级的为三维纳米材料,如纳米粉体;某二维尺寸为纳米量级的为二维纳米材料,如层状纳米材料;某一维尺寸为纳米量级的为二维纳米材料,如纳米纤维.     

Minimal memetics and the Evolution of Patented Technology

The nature and status of cultural evolution and its connection with biological evolution are controversial in part because of Richard Dawkin’s suggestion that the scientific study of culture should include “memetics,” an analog of genetics in which genes are replaced by “memes”—the hypothetical units of cultural evolution. Memetics takes different forms; I focus on its minimal form, which claims merely that natural selection shapes to some extent the evolution of some aspects of culture. Advocates and critics of memetics disagree about the scientific status of memetics, but they agree that memetics must face the following fundamental problems. Problem 1: Cultural evolution differs too much from biological evolution. Problem 2: Culture is too complex. Problem 3: Memes are too difficult to identify and track. Problem 4: Memetics produces only trivial results. This paper examines these problems in the context of a minimal memetic analysis in one specific context: patented inventions. Technology is a special subset of culture, and patented inventions are a special subset of technology—not least because there is a detailed written record of every patent. I describe four recent empirical results on technological innovation derived from memetic analysis of the patent record. Result 1: Inkjet printing, PCR, and stents are key drivers of technological innovation. Result 2: Patent genealogies are tangled and incestuous. Result 3: Door-opening innovations drive the evolution of technology. Result 4: The evolving content of the drivers of innovation confirms the importance of inkjet printing, PCR, and stents, among other inventions. These results show that minimal memetics can provide a novel and illuminating analysis the evolution of patented technology. Furthermore, this memetic analysis can answer all of the main problems with memetics. Problem 1 can be dismissed because culture and biology can be quite disanalogous, provided that natural selection still operates in both. Problem 2 is a mirage, because memetic analysis of the patented inventions is consistent with the full richness and complexity of the evolution of technology. Problem 3 is easy to solve, because the patent record makes it trivial to identify and track patents and their key traits through lineages. Problem 4 can be fully answered only after memetic analysis becomes widespread, but the results reviewed here shows that minimal memetics does yield scientific results that are nontrivial and interesting.     

三维有序纳米孔洞碳酸钙单晶材料的仿生构筑

自然界的生物矿化过程往往受到生物体的精细调控,从而生成各种具有复杂形态或多级有序结构并呈现出特定功能的生物矿物。利用自然界中的生物矿化原理来仿生构筑具有多级有序结构的无机功能材料不仅有助于揭示生物矿化机理,而且可以大大推动当代材料科学的发展,仿生材料合成因此得到人们的高度重视^[1]。另一方面,在微纳尺度上具有三维有序图案化结构的无机单晶材料是新型电子、光学器件的重要组成部件,而如何实现对其可控制备则一直是人们面临的一项挑战。作为一种典型的生物矿物,碳酸钙在自然界广泛存在于各种海洋生物体的外骨架中,     

Construction of Efficient Identification Schemes Using Batches of Discrete-Valued Tests

Well established methods are available for identifying a specimen from a known set of taxa by applying either a single set of tests, or a hierarchical sequence of single tests. These are relevant respectively when the cost of the tests or the time required for identification is most important. Often, however, a mixed strategy is required which aims to reduce the cost of identification while avoiding taking too much time. Methods are derived for constructing efficient identification schemes which involve the sequential use of batches of tests. Also, the special case is considered where an initial batch of tests is used, followed by a second batch whose composition depends on the results observed for the initial batch.     

术语的音译法及其创新

音译法是常用的术语翻译方法之一。术语音译法主要应用于4种范畴:1)新型材料和化学品名称;2)新发现的自然现象或物质;3)计量单位;4)首字母缩略词构成的术语。术语音译法的创新模式主要有7种:1)零翻译;2)纯音译;3)谐音译;4)音义结合法;5)形译法;6)省音译;7)创造新词。人们应该大胆地创造新的音译法。     

术语的音译法及其创新

音译法是常用的术语翻译方法之一。术语音译法主要应用于4种范畴：1）新型材料和化学品名称;2）新发现的自然现象或物质;3）计量单位;4）首字母缩略词构成的术语。术语音译法的创新模式主要有7种：1）零翻译;2）纯音译;3）谐音译;4）音义结合法;5）形译法;6）省音译;7）创造新词。人们应该大胆地创造新的音译法。     

论唐代的地名学成就

唐朝地名学在３个方面取得了新的进步：（１）地名学规律的总结与运用，包括“因水为名”命名原则的最终完善、“因原而名”等原则的首次提出等；（２）地名渊源解释丰富，仅《元和郡县志》一书就达２４类、９３１处；（３）开展地名“标准化”运动，贞观年间州县省并缓解了唐初的地名混乱状况，开元十三年（７２５年）更改州名提出了整理地名的基本原则“避文相类及声相近者”，而天宝元年（７４２年）更改天下１１０处县名，使同名县大大减少，大部分县名变得通俗易懂、易写易记。唐代地名学之成就，既是承袭汉魏以来传统地名学并向前发展，又是学术本身发展的产物，还与统治者的重视有关。     

Functional Cluster Analysis via Orthonormalized Gaussian Basis Expansions and Its Application

We propose functional cluster analysis (FCA) for multidimensional functional data sets, utilizing orthonormalized Gaussian basis functions. An essential point in FCA is the use of orthonormal bases that yield the identity matrix for the integral of the product of any two bases. We construct orthonormalized Gaussian basis functions using Cholesky decomposition and derive a property of Cholesky decomposition with respect to Gram-Schmidt orthonormalization. The advantages of the functional clustering are that it can be applied to the data observed at different time points for each subject, and the functional structure behind the data can be captured by removing the measurement errors. Numerical experiments are conducted to investigate the effectiveness of the proposed method, as compared to conventional discrete cluster analysis. The proposed method is applied to three-dimensional (3D) protein structural data that determine the 3D arrangement of amino acids in individual protein.     

Evolutionary and psychological effects in pre-evolutionary classifications

Relative frequency of genera as a function of number of species per genus is plotted for six eighteenth-century classifications: Linnaeus' classifications of animals, plants, minerals, and diseases, and Sauvages' classifications of plants and diseases. The distributions for animals and plants form positively skewed hollow curves similar but not identical to those found in modern biological classifications and predicted by mathematical models of evolution. The distributions for minerals and diseases, however, are more nearly symmetric and convex. The difference between the eighteenth-century and modern classifications of animals and plants probably reflects psychological properties of the taxonomists' judgments; but the difference between the classifications of animals and plants and those of minerals and diseases reflects evolutionary properties of the materials classified, since all six classifications were constructed by the same taxonomists using the same methods. Consequently, the observable effects of evolution are strong enough to be detected in classifications constructed before the acceptance of evolutionary theory; and traditional classifications can contain substantial scientific information despite their reliance on incompletely understood processes of judgment.I thank Mae Ling Hum for assistance in data collection, and Dennis G. Fisher, David M. Raup, Thomas D. Wickens, and J. Arthur Woodward for helpful comments on earlier versions of the paper. Computer time was provided by the UCLA Office of Academic Computing.     

Minimum sum of diameters clustering

The problem of determining a partition of a given set ofN entities intoM clusters such that the sum of the diameters of these clusters is minimum has been studied by Brucker (1978). He proved that it is NP-complete forM3 and mentioned that its complexity was unknown forM=2. We provide anO(N ³ logN) algorithm for this latter case. Moreover, we show that determining a partition into two clusters which minimizes any given function of the diameters can be done inO(N ⁵) time.Acknowledgments: This research was supported by the Air Force Office of Scientific Research Grant AFOSR 0271 to Rutgers University. We are grateful to Yves Crama for several insightful remarks and to an anonymous referee for detailed comments.