Overview of Rubik's Cube and Reflections on Its Application in Mechanism

Rubik’s Cube is a widely popular mechanical puzzle that has attracted attention around the world because of its unique characteristics. As a classic brain-training toy well known to the public, Rubik’s Cube was used for scientific research and technology development by many scholars. This paper provides a basic understanding of the Rubik’s Cube and shows its mechanical art from the aspects of origin and development, characteristics, research status and especially its mechanical engineering design, as well as making a vision for the application in mechanism. First, the invention and origin of Rubik’s Cube are presented, and then the special characteristics of the cube itself are analyzed.After that, the present researches of Rubik’s Cube are reviewed in various disciplines at home and abroad, including the researches of Rubik’s Cube scientific metaphors, reduction algorithms, characteristic applications, and mechanism issues. Finally, the applications and prospects of Rubik’s Cube in the field of mechanism are discussed.

基于改进Marching Cubes算法的雷达气象数据三维重建

在气象领域中,多普勒天气雷达探测到的气象数据采用以雷达站点为原点的三维极坐标系进行存储,具有形状不规则、数据量大等特征。Marching Cubes(MC)算法是三维重建中的经典算法,但应用于气象领域时存在重建效率低下和不能直接处理气象数据的缺点。为了实现气象数据的三维重建,基于MC算法提出雷达数据归一化处理与状态标记判别算法NBV-MC。该算法根据雷达基数据文件的特点对其进行归一化预处理,使用雷达基数据构建拟梯形六面体体素,对每一个六面体体素进行状态标记,在遍历六面体体素时动态判别其是否需要处理。实验结果表明,NBV-MC算法不仅解决了由于气象数据具有不规则性而不能直接用于MC算法的问题,而且可以在保证数据真实性和重建效果的情况下有效减少绘制等值面所需要的三角面片数量,提高重建速度。与MC算法相比,NBV-MC算法的重建效率提升了77.70%以上,有利于实时场景交互,便于气象研究人员直接分析雷达数据。

CUBE自动滤波在远海多波束测深中的应用

为提升远海多波束测深数据标准化处理能力,验证CUBE自动滤波在远海海域的实际应用效果,选取远海海域3个典型深度测区,使用优选的CUBE自动处理参数组,对多波束测深数据进行自动滤波处理,并从处理用时、逐点标记以及交叉点水深差值3个方面,将处理结果与多名作业人员的手工处理结果进行对比分析。实验结果表明,使用CUBE自动处理与人工处理结果基本相同,且少量处理不同之处产生的水深成果差值均在测量误差允许范围之内,且CUBE自动处理在处理效率、成果标准一致性方面均优于人工处理。本文成果对于提升远海多波束测深数据标准化处理能力具有较强的实践指导意义。

The Mechanism of Cube Texture Formation in Ni-7 at%W Substrate

In order to obtain the sharp cube texture,a new process,the intermediate annealing rolling technique,has been introduced to prepare the Ni7W substrate.In this paper,a cubic texture content up to 98.5%within 10°of the standard cubic orientation is obtained in the final substrate and the influence of this improved rolling technique on the cube texture formation has been discussed.The results show that the increased cube texture in the Ni7W substrate is caused by the optimized deformation texture and the increased nucleated fraction of the cube grains.

An Improved Framework of Massive Superpoly Recovery in Cube Attacks Against NFSR-Based Stream Ciphers

A critical problem in the cube attack is how to recover superpolies efficiently.As the targeting number of rounds of an iterative stream cipher increases,the scale of its superpolies becomes larger and larger.Recently,to recover massive superpolies,the nested monomial prediction technique,the algorithm based on the divide-and-conquer strategy,and stretching cube attacks were proposed,which have been used to recover a superpoly with over ten million monomials for the NFSR-based stream ciphers such as Trivium and Grain-128AEAD.Nevertheless,when these methods are used to recover superpolies,many invalid calculations are performed,which makes recovering superpolies more difficult.This study finds an interesting observation that can be used to improve the above methods.Based on the observation,a new method is proposed to avoid a part of invalid calculations during the process of recovering superpolies.Then,the new method is applied to the nested monomial prediction technique and an improved superpoly recovery framework is presented.To verify the effectiveness of the proposed scheme,the improved framework is applied to 844-and 846-round Trivium and the exact ANFs of the superpolies is obtained with over one hundred million monomials,showing the improved superpoly recovery technique is powerful.Besides,extensive experiments on other scaled-down variants of NFSR-based stream ciphers show that the proposed scheme indeed could be more efficient on the superpoly recovery against NFSR-based stream ciphers.

Quasi-static and dynamic compressive behaviour of additively manufactured Menger fractal cube structures

This paper presents the first-ever investigation of Menger fractal cubes'quasi-static compression and impact behaviour.Menger cubes with different void ratios were 3D printed using polylactic acid(PLA)with dimensions of 40 mm×40 mm×40 mm.Three different orders of Menger cubes with different void ratios were considered,namely M1 with a void ratio of 0.26,M2 with a void ratio of 0.45,and M3with a void ratio of 0.60.Quasi-static Compression tests were conducted using a universal testing machine,while the drop hammer was used to observe the behaviour under impact loading.The fracture mechanism,energy efficiency and force-time histories were studied.With the structured nature of the void formation and predictability of the failure modes,the Menger geometry showed some promise compared to other alternatives,such as foams and honeycombs.With the increasing void ratio,the Menger geometries show force-displacement behaviour similar to hyper-elastic materials such as rubber and polymers.The third-order Menger cubes showed the highest energy absorption efficiency compared to the other two geometries in this study.The findings of the present work reveal the possibility of using additively manufactured Menger geometries as an energy-efficient system capable of reducing the transmitting force in applications such as crash barriers.

基于X-CUBE-AI的神经网络手语识别系统设计

手语交流是聋哑人与他人交流的主要方法,设计了一款基于STM32的神经网络手语识别系统,采用TensorFlow和Keras机器学习框架训练网络模型,由于训练数据的局限性,加入L2正则化以解决训练过拟合问题。使用意法半导体推出的STM32Cube.AI工具包在STM32嵌入式平台上部署神经网络,搭载OV2640摄像头采集图像并进行缩放处理,将图像数据传入网络进行推理可获得识别结果。经测试,网络模型获得了较好的鲁棒性和适应性,在STM32上运行平均每帧推理时间为15.8 ms,平均准确率达92.3%。使用STM32作为手语识别终端,极大地提高了设备的便携性,节约成本,反应迅速。为聋哑人与正常人交流提供了一种新的解决方案,具有较高的实际应用价值。

MRI 3D CUBE T_(2)序列检查在踝关节外伤患者韧带损伤诊断中的价值

目的:研究MRI 3D CUBE T_(2)序列检查在踝关节外伤患者韧带损伤诊断中的价值。方法:选择2020年4月—2023年4月于白银市第一人民医院就诊的226例踝关节外伤拟行手术术前患者作为研究对象,按照不同检查方式将患者分为观察组(n=126)与对照组(n=100)。观察组采用MRI 3D CUBE T_(2)序列检查,对照组采取常规MRI检查。比较两组患侧、健侧距腓前韧带测量结果、诊断效能。结果:两组患侧、健侧距腓前韧带宽度及厚度比较,差异无统计学意义(P>0.05)。观察组Ⅰ级踝关节外伤患者韧带损伤诊断准确度、敏感度、特异度、阳性预测值、阴性预测值高于对照组,Ⅱ级患者准确度、敏感度、阴性预测值高于对照组,Ⅲ级患者准确度、特异度、阳性预测值高于对照组,差异有统计学意义(P<0.05)。结论:MRI 3D CUBE T_(2)序列检查踝关节外伤患者韧带损伤诊断效能高于常规MRI检查,可作为治疗效果评价及康复治疗的重要依据。

Efficient electrocatalytic conversion of N_(2) to NH_(3) using oxygen-rich vacancy lithium niobate cubes

Instead of the energy-intensive Haber-Bosch process,the researchers proposed a way to produce ammonia using water and nitrogen as feedstock,powered by electricity,without polluting the environment.Nevertheless,how to design efficient electrocatalyst for electrocatalytic nitrogen reduction reaction(NRR)is still urgent and challenging.Herein,a strategy is proposed to adjust the morphology and surface electronic structure of electrocatalyst by optimizing material synthesis method.LiNbO3(lithium niobate,LN)cubes with oxygen-rich vacancy and regular morphology were synthesized by hydrothermal synthesis and followed molten salt calcination process,which were used for electrocatalytic NRR under mild conditions.Compared with LN nanoparticles synthesized by solid phase reaction,LN cubes exhibit better NRR performance,with the highest ammonia yield rate(13.74μg.h^(-1).mg^(-1))at the best potential of-0.45V(vs.reversible hydrogen electrode,RHE)and the best Faradaic efficiency(85.43%)at-0.4 V.Moreover,LN cubes electrocatalyst also demonstrates high stability in 7 cycles and 18 h current-time tests.Further investigation of the reaction mechanism confirmed that the structure of oxygen vacancy could adjust the electronic structure of the electrocatalyst,which was conducive to the adsorption and activation of N_(2) molecule and also increased the ECSA of electrocatalyst,thus providing more active sites for the NRR process.

基于SPH的新型人工块体TB-CUBE设计优化和水动力特性数值模拟

为探究高透空性新型人工块体TB-CUBE的最优结构尺寸型式及其水动力特性,利用基于光滑粒子方法(smoothed particle hydrodynamics,SPH)的DualSPHysics开源代码开展斜坡堤新型人工块体TB-CUBE数值模拟研究,探究其在规则波作用下的爬高和越浪等水动力特性及波浪变化规律。结果表明:数学模型模拟的爬高和越浪与物理模型试验的实测值误差分别在6%和9%以内,可较好地刻画波浪在人工块体上的演变过程。基于此验证模型,分析不同细部尺寸参数下块体的水动力特性,综合块体爬高、反射系数、越浪、块体孔隙率和材料用量等因素,得到最优消浪效果所对应TB-CUBE块体的球相对半径R1、圆柱相对半径R2与块体边长h的关系。在此基础上,以优化后的TB-CUBE块体为对象,分析其爬高和越浪的过程,揭示出该块体的消浪机理主要为相邻块体之间的圆孔对波浪的爬高和回落均有阻滞作用,且块体内部孔隙可以容纳水体并形成紊流效能,可以相应地减少波浪的爬高。此外,研究斜坡坡度、堤前水深、入射波高和波周期等对波浪爬高的影响,得到TB-CUBE块体爬高随入射波高和波坦的增大而增大,而随坡度的变化呈现单峰曲线的变化趋势。进一步考虑不同波浪破碎形态对波浪爬高的影响,拟合得出TB-CUBE块体的爬高经验公式,公式拟合值与模型计算值相关系数达0.981,能够真实反映该块体的爬高情况,为今后该块体在海岸工程中的实践运用提供科学依据。

JOHN-NIRENBERG-Q SPACES VIA CONGRUENT CUBES

To shed some light on the John-Nirenberg space,the authors of this article introduce the John-Nirenberg-Q space via congruent cubes,JNQp,qα(Rn),which,when p=∞and q=2,coincides with the space Qα(Rn)introduced by Essen,Janson,Peng and Xiao in[Indiana Univ Math J,2000,49(2):575-615].Moreover,the authors show that,for some particular indices,JNQp,qα(Rn)coincides with the congruent John-Nirenberg space,or that the(fractional)Sobolev space is continuously embedded into JNQp,qα(Rn).Furthermore,the authors characterize JNQp,qα(Rn)via mean oscillations,and then use this characterization to study the dyadic counterparts.Also,the authors obtain some properties of composition operators on such spaces.The main novelties of this article are twofold:establishing a general equivalence principle for a kind of’almost increasing’set function that is here introduced,and using the fine geometrical properties of dyadic cubes to properly classify any collection of cubes with pairwise disjoint interiors and equal edge length.

Hierarchical Datacubes

Many approaches have been proposed to pre-compute data cubes in order to efficiently respond to OLAP queries in data warehouses. However, few have proposed solutions integrating all of the possible outcomes, and it is this idea that leads the integration of hierarchical dimensions into these responses. To meet this need, we propose, in this paper, a complete redefinition of the framework and the formal definition of traditional database analysis through the prism of hierarchical dimensions. After characterizing the hierarchical data cube lattice, we introduce the hierarchical data cube and its most concise reduced representation, the closed hierarchical data cube. It offers compact replication so as to optimize storage space by removing redundancies of strongly correlated data. Such data are typical of data warehouses, and in particular in video games, our field of study and experimentation, where hierarchical dimension attributes are widely represented.

神奇的立方宝贝--CUBE BABY AC

这次我为大家推荐的是来自笙科智能公司的CUBE BABY AC,相比国际上的大品牌,例如雅马哈、罗兰、Korg,国内这家珠海的科技公司确实是名不见经传。毕竟市场的份额就这么多,想做出有创新的产品,就必须投入大量的研发精力。而这家公司的运营方式很奇特,只做中低端市场,以最便宜的价格拿到更有“性价比”的产品。那在乐器行业中什么是“性价比”呢?是售价低廉还是音质越级,是做工出色还是极致创新?在搜索引擎上。

798CUBE美术馆,北京,中国

798CUBE美术馆是一个改造项目,位于798艺术区内,与毗邻佩斯美术馆和民生现代美术馆一道,是朱锫建筑近些年来以工业遗产为主题的一系列实验性的创作实践。美术馆的构思始于对特定地段环境敏感深入观察,尽最大的可能保留原有的工业厂房,在此基础上,再注入新的建筑,从而编织出新老建筑之间的张力,并与周边工业建筑,如佩斯美术馆、民生现代美术馆等建筑,彼此缝合,相互补充。

茶多酚在鲜切脆山药块加工中的应用效果

为明确茶多酚(白色)对鲜切脆山药的护色、抑菌效果,配制5种不同浓度的茶多酚溶液对脆山药块进行浸泡5 min处理,以清水和生产上的常规处理(次氯酸钠)为对照,定期检测失重率、褐变度、菌落总数、大肠埃希氏菌MPN值,并进行感官评价。结果表明,与对照相比,4℃条件下,5种不同浓度茶多酚处理均能延缓脆山药块的氧化褐变,降低褐变度,保持良好的外观品质和商品性,延长产品货架期至7 d以上。其中,以0.2%茶多酚对脆山药块的保鲜效果最好,感官品质佳,保鲜期11 d,抑菌期12 d,褐变度为5.46%,菌落总数为2.17×10^(4) CFU·g^(-1),大肠埃希氏菌MPN值<0.3。在实际生产中,可根据货架期要求,选择不同浓度的茶多酚处理。研究结果为生产企业采用天然保鲜剂替代化学保鲜剂用于鲜切山药的抗氧化、抑菌等加工保鲜提供了有效指导。

序列密码立方攻击研究进展综述

立方攻击由Dinur和Shamir在2009年欧密会上首次提出,是一种高阶差分攻击和代数攻击.经过近十余年的研究,传统立方攻击不断发展,动态立方攻击、基于可分性的立方攻击、相关立方攻击相继提出,攻击思想不断丰富,攻击技术不断改进,逐渐成为针对基于非线性反馈移位寄存器的序列密码算法的重要攻击方法.特别地,立方攻击自2009年提出以来一直是国际轻量级序列密码标准Trivium最有效的密钥恢复攻击,动态立方攻击攻破了全轮Grain-128算法,Kreyvium、Grain-128AEAD、ACORN这些基于非线性反馈移位寄存器的序列密码算法都可以用立方攻击进行有效分析.本文介绍了立方攻击的基本原理和攻击方法,综述了实验立方攻击、基于可分性立方攻击、立方集构造、动态立方攻击、相关立方攻击等方面的研究进展.

双高箱办理站装卸设备协同调度研究

为提高双高箱列车装卸作业效率,针对双高箱办理站不设主作业区、“完全间接装卸”、装卸作业多流向及出站箱同步转运的特点,考虑设备能力、作业序列、轨道吊安全距离约束等现实约束,详细拆分设备间的衔接、共用及等待时间构成,以最小化完成装卸作业用时、装卸线轨道吊等待时间最小化和作业均衡率最大化为优化目标,构建轨道吊、AGV、空箱堆垛机和智能举升机间的协同调度模型,并基于遗传算法和模拟退火算法设计混合算法求解模型。通过实例验证模型及算法的有效性、混合算法和多目标协同优化的优越性,分析表明双高箱办理站布局及装卸作业模式可行,优化指标间两两无单向相关性。最后通过灵敏度分析验证模型可用于装卸设备配置优化,以实现双高箱办理站低成本高效运作。

魔方型智能仓储系统多AGV任务调度及优化

为探究针对魔方型仓储系统的多AGV调度问题,建立考虑倒箱因素的多AGV调度优化数学模型,设计改进的多层编码的遗传算法,有助于算法跳出局部最优并改善其局部搜索能力。通过设计不同算例,对比优化前后的AGV调度方案,验证改进算法的有效性和可行性,同时,对不同任务规模、AGV规模、仓储填充率、仓储立体规模和仓储平面规模五方面的工况进行探究分析,为魔方型仓储系统运行状况研究提供理论基础。

智能魔方仓库出入库作业虚拟仿真实验系统建设

智能魔方仓库具有存储密度大、集成度高等优点,在小件订单拣选领域发展迅速,但因其特殊的堆存形式使得出入库较之传统仓库多出一个翻箱的环节。为了直观展示出入库作业过程,在研究出入库、翻箱规则及机器小车调度策略的基础上,基于Unity 3D开发了智能魔方仓库出入库作业虚拟仿真实验系统。学生通过交互操作实现不同仓库规模、存储水平及订单数的出入库调度,对智能魔方仓库运作有更深切的认识。该系统可为仓储系统、机器小车调度等课程开展提供虚拟仿真实验环境,也是对现有仓储仿真软件的有效拓展。

PVA-ECC材料抗压强度及收缩性的时变规律研究

PVA-ECC材料的长期力学性能对港口工程结构加固修复至关重要。通过PVA-ECC材料不同龄期试块的抗压强度试验和收缩性试验对其宏观力学特性的时变规律进行了研究。研究表明,2%PVA掺量的PVA-ECC材料的流动性差,其在港口水工结构加固工程中的适用性有待进一步研究。通过抗压强度试验可知,随着龄期的增加,1.5%PVA掺量和1.8%PVA掺量的试块抗压强度呈现抛物线上升的趋势,经180d养护后的试块抗压强度分别达到69.4 MPa和76.1 MPa,是C40混凝土试块强度的1.5倍和1.6倍,从抗压强度分析,两者均满足加固工程的强度要求。根据材料收缩性对比试验可知,随着龄期的增加,三种试块的收缩率在0~28 d期间变化剧烈,在28d后变化均趋于平缓,不同PVA掺量的试块收缩率均大于C40混凝土试块,而1.5%PVA掺量的试块与C40混凝土试块收缩率更接近。鉴于1.5%PVA掺量的PVA-ECC材料流动性更能适应沿海港工结构加固的现场施工,同时,其收缩率与混凝土收缩率接近,且抗压强度足够高,因此,在港口工程结构加固修复中,推荐采用1.5%PVA掺量的PVA-ECC材料。同时,基于试验数据拟合得到了适合不同配比、不同龄期PVA-ECC材料的立方体抗压强度计算公式,可用于PVA-ECC材料的强度预测。