Ferroelectricity induced by the absorption of water molecules on double helix SnIP

We study the ferroelectricity in a one-dimensional(1D)system composed of a double helix SnIP with absorbing water molecules.Our ab initio calculations reveal two factors that are critical to the electrical polarization.The first one is the orientation of polarized water molecules staying in the R2 region of SnIP.The second one is the displacement of I atom which roots from subtle interaction with absorbed water molecules.A reasonable scenario of polarization flipping is proposed in this study.In the scenario,the water molecule is rolling-up with keeping the magnitude of its electrical dipole and changing its direction,meanwhile,the displacement of I atoms is also reversed.Highly tunable polarization can be achieved by applying strain,with 26.5%of polarization enhancement by applying tensile strain,with only 4%degradation is observed with 4%compressive strain.Finally,the direct band gap is also found to be correlated with strain.

EFFECT OF GEAR WIDTH AND HELIX ANGLE ON FACTOR OF DYNAMIC LOAD OF DOUBLE CIRCULAR ARC HELICAL GEARING

Based on theory of mechanical dynamics, meshing characteristic as well as thedynamic model of double circular arc helical gearing, an analysis approach and a computer programhave been developed for studying the state of dynamic load and factor of dynamic load of thegearing, the changing situation of dynamic load and dynamic load factor vs some affecting factorssuch as gear width, helix angle and accuracy grade etc are investigated. A series of conclusions areobtained: ①With the increasing in the values of gear width, the dynamic load factor appears slowdecreasing tendency in most region of gear width. ②When the accuracy grades of the gearing areimproved, the values of dynamic load factor decrease. ③The value of dynamic load factor appears adecreasing tendency with the increasing of value of helix angle at the same ratio of criticalrotational speed.

The charge transfer via a double helix DNA

This paper reports a double helix model of charge transfer in DNA molecule. The calculated results show that the transmission characteristics of DNA are not only related to the longitudinal transfer but also to the helicity of molecule. It finds that there are four transmission bands centred at 0.92, 3.07, 7.75 and 8.87eV, also the width and intensity of bands corresponding to the helix direction are less than that of the longitudinal direction. With the increase of hopping energy, transmission bands become wide so that the transmission ability is enhanced.

Explore the Mystery of the Origin of the Double Helix and the Biomembrane

In nature, the most possible reason that helix is chosen as the basic structure of life molecule is based on its simplest chiral three-dimensional structure. The process of the conversion from chemical molecules to double helical molecules is completed by the topology effect which belongs to the simplest way to form helix, and no external power is needed;moreover, the energy of double helix has fixed drive direction [1]. The dual-branch loop helix (II)—the transition state of double helix has many uses, for example, it can be turned to double helix, and it may be broken into two fragments of a and b which can construct more complicated structures. So the dual- branch loop helix (II) can provide special "building block" of assembling biomembrane and other life molecules.

Middle or low water pressure direct spiral double helix converging nozzle structure optimization and flow field analysis

In order to solve the problem of using middle or low water pressure to form fine water mist,a new nozzle is proposed in fire rescue robot.Existing water mist nozzles are basically used for high pressure and in large size,complex structure and poor low pressure atomization effect in comparison with requirement of snake-like fire rescue robots.On the basis of comprehensive typical spray nozzles,a direct spiral double helix converging nozzle(DSDHCN) is proposed,which has the advantages of small volume,light weight,simple structure,and convenient installation.To make the spray nozzle have good performance,and meet the requirements of more efficient fire extinguishing,a numerical study is carried out to analyze the internal and external full flow field of nozzle.A gas-liquid two-phase flow is applied to simulate the external full flow field of nozzle with VOF model in fluent software.The simulation results show the real situation of water flow out of the atomization nozzle and the water jet trajectory.Some simulations about middle or low water pressure direct spiral double helix converging optimized nozzle have been done in 30 bar pressure.The simulation results show that the optimized nozzle structure not only makes the spray droplets have a good cone angle,but also have a sufficient axial velocity,which proves the structure rationality of the proposed optimized nozzle.

Design and motion control analysis of double helix wall climbing robot

For the detection environment of complex walls such as high-rise buildings,a double helix wall climbing robot(DHWCR)with strong adsorption force and good stability is designed and developed,which uses symmetrical propellers to provide adsorption force.The symmetrical driving structure can provide smooth thrust for the DHWCR,so that the robot can be absorbed to the wall surface with different roughness.A left and right control frame with multiple degrees of freedom is designed,which can adjust the fixed position of the brushless propeller motor in the front and back directions,realize the continuous adjustable thrust direction of the robot,and improve the flexibility of the robot movement.Using the front wheel steering mechanism with universal joint,the steering control of the DHWCR is realized by differential control.In the vertical to ground transition,the front and rear brushless motors can provide the pull up and oblique thrust,so that the DHWCR can smoothly transition to the vertical wall.The motion performance and adaptability of the DHWCR in the horizontal ground and vertical wall environment are tested.The results show that the DHWCR can switch motion between the horizontal ground and vertical wall,and can stably adsorb on the vertical wall with flexible attitude control.The DHWCR can move at a fast speed.The speed on the horizontal ground is higher than that on the vertical wall,which verifies the feasibility and reliability of the DHWCR moving stably on the vertical wall.

SnIP-type atomic-scale inorganic double-helix semiconductors: Synthesis, properties, and applications

Flexible inorganic double helical semiconductors similar to DNA have fueled the demand for efficient materials with innovative structures and excellent properties.The recent discovery of tin phosphide iodide(SnIP),the first carbon-free double helical semiconductor at an atomic level,has opened new avenues of research for semiconducting devices such as thermoelectric and sensor devices,solar cells,and photocatalysis.It has drawn significant academic attention due to its high structural flexibility,band gap in the visible spectrum range,and non-toxic elements.Herein,the recent progress in developing SnIP,including its prestigious structure,versatile and intriguing properties,and synthesis,is summarized.Other analogues of SnIP and SnIP-based hybrid materials and their applications in photocatalysis are also discussed.Finally,the review concludes with a critical summary and future aspects of this new inorganic semiconductor.

What Governs the Unzipping Process of Double-Stranded DNA

双 stranded DNA 的解开的进程在基础水平用一个分离模型被分析[下巴。Phys。Lett。22 (2005 ) 1540 ] 。数字结果与包括 thesequence 依赖的力量排水量行为上的试验性的观察一致。我们发现在基础对的氢契约相互作用是到力量排水量侧面的 cruciallyimportant。

基于双螺旋式加热器的柔性MEMS流量传感器

针对传统流量传感器的量程限制,提出了一种基于双螺旋结构加热器的柔性基底微机电系统(MEMS)热式流量传感器。在基底上打出均匀通孔阵列以降低热传导损耗,两对测温电阻对称分布在加热器两侧,以获得较宽量程,在微小流量与大流量下均表现出较高灵敏度。采用基于惠斯通电桥的检测电路实现输出电压的测量,同时保持加热器与环境温度恒定温差200 K,对电阻自热进行补偿。传感器工作温度-100~400℃,量程为0~60 m/s;低流速下灵敏度约为12.75 V/(m·s^(-1)),分辨率可达0.001 mm/s,高流速下灵敏度约为1.4 mV/(m·s^(-1)),功耗低至1.3 mW。

基于双螺旋结构的声卡同步输入输出

为了提高在声卡应用中实现的录音、播放的同步性,采用回调函数里交叉调用录音、播放的操作,设计了一种新颖的回调递归逻辑链。该方法表现在录音、播放的两个时间线上,两条回调递归模式的逻辑循环构成了美妙的双螺旋结构,这个结构恰似生命科学里经典的基因双螺旋模型。双螺旋结构的录音播放程序机制有更好的中和抖动的结果,比常规的录音播放调度模式易于获得更优的同步效果。方法可应用于需要多路音频信号同步的场合,如声学回声消除、声源定位和有源降噪等领域,以便获得更优的同步,从而助力于对应的音频算法的效果。

用于三维单颗粒示踪的多焦面双螺旋点扩散函数显微研究

双螺旋点扩散函数(double-helix point spread function,DH-PSF)显微可实现纳米尺度的三维单颗粒示踪(three-dimensional single particle tracking,3D SPT),被广泛应用于生命科学等领域,但DH-PSF显微的成像景深和定位精度有限,限制了其在活体厚样品中的应用.为了解决此问题,本文提出了一种基于轴向分光棱镜的多焦面DH-PSF显微(z-splitter prism-based multifocus DH-PSF microscopy,ZPMDM)方法和系统,通过将基于轴向分光棱镜的多焦面显微与DH-PSF相结合,在无需扫描的情况下提高DH-PSF显微的轴向定位范围和定位精度,解决完整活细胞内3D SPT的大景深探测难题.通过系统标定,ZPMDM中3个通道的平均三维定位精度分别为σ_(L(x,y,z))=(4.4 nm,4.6 nm,10.5 nm),σ_(M(x,y,z))=(4.3 nm,4.2 nm,8.2 nm),以及σ_(R(x,y,z))=(4.8 nm,4.4 nm,10.3 nm),DH-PSF的有效景深扩展至6μm,实现了大景深范围内的甘油-水混合溶液中的荧光微球示踪,并初步研究了活巨噬细胞的吞噬现象,进一步验证了该方法的有效性,对于3D SPT的发展和应用具有重要意义.

高职院校“双螺旋”结构产教融合生态模式的构建

高职院校产教融合存在融合度低、融合模式缺乏凝练及组织结构松散、尚未建立稳定的长效合作机制等问题,导致高职院校人才培养质量不高、服务企业创新能力不强。以互惠共生理念和利益相关者理论为指导,创新性地构建“双螺旋”结构产教融合生态模式,建立产教融合长效机制,以期促进高职院校产教融合可持续发展。

基于自适应Kriging模型的双螺旋轴可靠性分析

双螺旋轴是高速水稻插秧机的关键部分,其回转槽面在强轴向力作用下容易破坏失效,因此对双螺旋轴进行可靠性分析十分重要.针对传统方法获得其可靠度耗资大、时间长的问题,采用自适应Kriging模型结合Monte Carlo模拟的可靠性分析方法(AK-MCS)对双螺旋轴进行可靠性分析,以减少计算成本、提高计算效率.根据双螺旋轴的工况条件,考虑材料密度、工作载荷、工作温度3个参数对其所受挤压应力的影响,进行可靠性分析.分析结果表明:在许用应力值为613.21 MPa的条件下,计算得出双螺旋轴的可靠度为0.9986.与单一的Monte Carlo模拟法进行对比,本文提出的评估方法在仿真效率上有明显优势,为双螺旋轴可靠性分析提供了一种思路.

桨叶结构参数对双行星搅拌混合过程的模拟影响

为探究双行星搅拌机桨叶结构参数对锂电池浆料混合过程的影响,以3 L锂离子电池浆料双行星搅拌机为研究对象,采用standard k-ε模型,通过动网格法开展结构参数对搅拌过程中混合特性影响的数值模拟。结果表明:桨叶的结构参数对循环性能、剪切性能和功率特性均有影响,随着桨叶螺旋角的增大,双行星搅拌机的轴向循环能力提高,径向循环能力降低,且增大螺旋角与减小间隙会增强搅拌机的剪切性能同时增大功耗;在3个混合性能评价指标中,剪切性能受影响最显著,结构参数对剪切特性影响的主次顺序为桨叶螺旋角>桨叶间隙。通过正交试验分析,最优组合为桨叶螺旋角50°、桨叶间隙6 mm。

互动耦合:文旅融合如何助力乡村振兴——基于双螺旋模型的多案例分析

从文旅融合与乡村振兴两个核心概念出发,采用案例分析方法,借助双螺旋耦合模型探索出文旅融合助力乡村振兴路径为“文化活化保护传承”“休闲农业生态观光”“IP市场延伸发展”“文旅服务效能提升”“特色开发文旅产业”5种理想类型,在此基础上剖析文旅融合助力乡村振兴机理。结果表明:文旅融合发展中的五个维度与乡村振兴的五大振兴目标是“两两互补配对”形成相互助力、相互影响的“强关联状态”的双螺旋互动耦合关系。以文旅资源融合激发文化振兴、文旅业态融合实现产业振兴、文旅市场融合强化人才振兴、文旅服务融合赋能组织振兴、文旅空间融合推动生态振兴。研究为多样化的文旅融合模式助力乡村振兴实践路径提供了理论和逻辑上的支撑,也为引导文旅融合助力乡村振兴赋予了更大的灵活性和调整的空间。

莲藕施肥机无轴双螺旋供肥装置性能分析与试验

针对藕田施肥过程中存在的劳动强度高、施肥稳定性及均匀性较低的问题,设计了一种水力喷射式莲藕施肥机,其主要分为供肥装置和水肥混合装置,主要对无轴双螺旋供肥装置进行了设计与分析。通过理论分析确定影响供肥性能参数主要为螺旋转速、直径和导程,结合藕田施肥农艺要求确定上述3项参数的取值范围。利用EDEM对无轴双螺旋供肥性能进行离散元仿真分析,以供肥量均值和供肥量稳定性变异系数为评价指标分别进行单因素试验和回归正交旋转组合试验。单因素试验结果表明:供肥量均值随着螺旋转速、直径和导程的增大而增大,并且具有良好的线性关系,因此可通过调节供肥螺旋转速、直径和导程来改变供肥量均值;供肥量稳定性变异系数随着螺旋转速和导程的增大呈现先降低后升高的趋势,而随着直径的增大而减小。运用Design-Expert软件对回归正交旋转组合试验结果进行分析优化,分别开展仿真试验和台架试验对优化后的参数进行验证。结果表明,当螺旋转速为160 r·min^(-1),螺旋直径为78 mm,螺旋导程为53 mm时,仿真结果供肥量均值为329.43 g·s^(-1),供肥量稳定性变异系数为1.43%,台架试验结果分别为341.32 g·s^(-1)和2.34%,满足藕田施肥农艺及供肥稳定性要求。该研究可为螺旋式供肥装置的设计优化及藕田机械化施肥提供参考。

应急管理中技术赋能失灵的三种类型——基于双螺旋赋能机理的分析

技术赋能是提升应急管理能力的重要途径,但不可否认也存在一定程度的技术赋能失灵现象。是什么关键要素导致了应急管理中的技术赋能失灵?技术赋能失灵背后有何类型化特征?研究发现:以双螺旋赋能机理为理论基础,应急管理中的技术赋能失灵存在于技术端与管理端自催化和异催化过程,主要可归纳为技术主导型、管理主导型及“技术-管理”互动型赋能失灵三种类型。结合应急管理中实践的多种现象,对其中技术赋能失灵现象的内在机理进行简要剖析,由此可知,未来高新技术对应急管理的长期有效赋能要通过技术与管理两端多个层面上的综合施策推动技术与管理的有机深度融合,共同实现应急管理中技术的可持续包容性赋能。

WSR方法论视角下的智库双螺旋问题研究范式探索——以我国高水平智库地域发展差异问题为例

智库是国家软实力和话语权的重要组成部分,是科学问题分析和科技情报研究的重要力量。智库的作用发挥主要依托于智库研究成果,而高水平研究成果的形成需要科学的智库问题研究范式指导。智库双螺旋法是我国智库研究和问题分析领域逐渐兴起的一种科学范式,“物理(Wu)—事理(Shi)—人理(Ren)”WSR方法论是一种处理复杂问题的系统工程理论。分析二者内在机理,将系统工程理论中的WSR方法论引入智库双螺旋法,从宏观和微观角度探索对智库双螺旋法的补充和发展。以我国高水平智库地域发展差异问题为例,开展WSR方法论视角下的智库双螺旋法应用研究。WSR方法论视角下的智库双螺旋法是智库问题研究范式新路径的探索。WSR方法论为智库双螺旋法的构建提供了一种理论阐释,丰富了智库双螺旋法的分析维度和耦合结构,发展了智库问题研究的方法手段。探索引入WSR方法论的智库双螺旋问题研究范式有其科学意义和实践价值。

“双循环”格局中职业教育“一衔二融三教”育人模式研究

文章从“双循环”背景出发,构建了职业教育与地区经济融合高质量发展的“一衔二融三教”育人框架,探究职业教育育人过程中易发生的偏差,以期为新时代职业教育的效能优化提供开拓性解题思路。为实现人才培养与劳动力市场高效衔接,职业教育可以从理念、教材、教法上改进原有模式,在尊重学生主观能动性之余,融合学科理论与技能讲授,贯通学历教育与社会职业资格,兼顾多类、多样及终身的教育需求,突破单纯的学龄人口教育,以进一步实现受教育群体在知识、技能、行动、意志和品性等多个维度的融合与交互。

模具专业复合型创新性人才“五链融合、双螺旋”协同育人模式研究与实践

针对模具专业复合型创新性人才的需求,创新建立“五链融合、双螺旋”协同育人模式,实现企业拉动产业链,学校助推教育链,市场引领创新链,行业提升价值链。以行业为指导,促进内外部价值增值,学生浸润精益求精的企业文化,实现文化协同;以市场为导向,建立育人机制以及各项管理制度,实现管理协同。以学校为主体,创新课程体系,确定双师教学团队及车间式教学模式的培养对象,实现人员协同;以企业为主体,共建产学研教协同平台,为教师能力的提高、企业新员工培训及老员工晋升提供保障,实现资源协同“;校行企市”协同培养模具复合型创新性人才,解决学生就业难,企业招工难的问题,实现利益协同。