大深径比长管相交孔口边缘毛刺去除工艺研究

为解决身管抽气孔边缘毛刺去除需求,根据磨料刷去除毛刺机理建立磨料刷加工载荷三要素理论计算模型,借助ABAQUS/CAE的扩展有限元法(Extend Finite Element Method,XFEM)分析载荷三要素对加工后残余毛刺的影响规律,通过响应面方差分析方法得出三要素对结果影响程度由大到小依次为加载面积>加载方向>载荷大小,并由二阶回归方程计算出最优的载荷工况。通过所建立的模型联立求得最佳磨料刷加工工艺参数,并依据加工原理研制出专用装置进行加工实验,实现抽气孔边缘无毛刺的表面质量提升。

4D印刷——让生活增添“新的维度”

随着3D印刷技术的不断升温,越来越多的3D印刷物品进入市场。然而在3D增材制造技术的发展中,由一般材料的3D印刷到智能材料的增材制造技术已经逐渐成为趋势。作为3D印刷技术升级版,智能材料增材制造技术即称之为4D印刷已经在市场中＂初露头角＂。

SCOURS IN FRONT OF A BREAKWATER BY BROKEN WAVES AND THEIR SIMILARITY LAW

The sea bottom in front of a breakwater is scoured under the action of broken waves,and this will affect the stability of the breakwater.In this paper,the scours of sandy seabed in front of a breakwater under the action of broken waves are investigated experimentally.The depth and range of the scouring trough at the foot of a breakwater are studied,and the influence of open foundation-bed on scouring and depositing is also discussed.In order to apply the research results to practical projects,the scale of model sediment and the scale of scours and depositions are suggested.

ROTOR FAULT DIAGNOSIS OF BRUSHLESS AC GENERATOR WITH ROTARY RECTIFIER

With a three-phase bridge type rectification, some typical rotor faults of a brushless AC generator with a rotary rectifier is analyzed in this paper by the help of computer digital simulation. It is also proPOsed that the rotor faults, whether exist or not, and the causes of the faults may be determined through the monitoring of the average value of the exciting current of the exciter and its principal harmonics.

《我们的牙齿》教学设计

教学的基本思路 《我们的牙齿》这一课,教学生通过观察了解自己的牙齿,达到教育学生保护牙齿的目的。因此,观察什么,怎样进行教育,是要着力研究的问题。 数一数牙齿有多少颗,历来的教科书都有这项观察内容。但是低年级学生数自己的牙齿很费力,数出的数目不准确,往往把一颗臼齿数成两颗,而且各个学生的发育状况不尽相同,牙齿的颗数也不同。这就需要考虑数牙齿有什么意义。

选择瓦楞纸板是确定油墨组份的关键

在瓦楞纸板上进行柔版印刷的最常用的方法是把油墨从印刷模(printing die)上转移瓦楞纸板上.进入美国市场的另一种方法是压电按需滴落喷墨印刷.这种方法没有用来转移油墨的印刷模.由于借助印刷头压力的改变而使油墨喷射到瓦楞纸板上,因此名字叫做"按需滴落".

An Enhanced Physically Based Scour Model for Considering Jet Air Entrainment

Based on systematic experiments on the influence of air entrainment on rock block stability in plunge pools impacted by high-velocity jets,this study presents adaptations of a physically based scour model.The modifications regarding jet aeration are implemented in the Comprehensive Scour Model(CSM),allowing it to reproduce the physical-mechanical processes involved in scour formation concerning the three phases;namely,water,rock,and air.The enhanced method considers the reduction of momentum of an aerated jet as well as the decrease of energy dissipation in the jet diffusive shear layer,both resulting from the entrainment of air bubbles.Block ejection from the rock mass depends on a combination of the aerated time-averaged pressure coefficient and the modified maximum dynamic impulsion coefficient,which was found to be a constant value of 0.2 for high-velocity jets in deep pools.The modified model is applied to the case of the observed scour hole at the Kariba Dam,with good agreement.

Calculation of the ultimate depth of a scour pit after debris flow through drainage canal ribs

Drainage canals are engineering structures widely used for debris flow mitigation.When passing through a drainage canal,debris flow usually scours the gully bed at the back of the rib sill of the drainage canal,which leads to failure of the rib sill.Therefore,the scour depth at the back of the rib sill is an important design problem and it is related to the economic benefits of engineering and service years.To explore the law of the depth of the scour pit after debris flow through drainage canal ribs,we first proposed a formula for the calculation of the maximum scour depth at the back of a rib sill based on energy conservation.We then conducted a series of simulation experiments to test the proposed formula.The experimental results show that the scour depth,trench slope and the distance between ribs all increase with a decrease in debris flow density.We then compared the results of experiments and formula calculations.Through the testing analysis,we found that the calculation results of the conductedformula correspond with the experimental results better.Finally,taking Qipan Gully as an example,we designed the ultimate depth of a drainage canal for debris flow using the calculation formula.

Numerical Modeling of Local Scour Around Hydraulic Structure in Sandy Beds by Dynamic Mesh Method

Local scour, a non-negligible factor in hydraulic engineering, endangers the safety of hydraulic structures. In this work, a numerical model for simulating local scour was constructed, based on the open source code computational fluid dynamics model Open FOAM. We consider both the bedload and suspended load sediment transport in the scour model and adopt the dynamic mesh method to simulate the evolution of the bed elevation. We use the finite area method to project data between the three-dimensional flow model and the two-dimensional(2D) scour model. We also improved the 2D sand slide method and added it to the scour model to correct the bed bathymetry when the bed slope angle exceeds the angle of repose. Moreover, to validate our scour model, we conducted and compared the results of three experiments with those of the developed model. The validation results show that our developed model can reliably simulate local scour.

Analysis of Do D inkjet printhead performance for printable electronics fabrication using dynamic lumped element modeling and swarm intelligence based optimal prediction

The major challenge in printable electronics fabrication is to effectively and accurately control a drop-on-demand(Do D) inkjet printhead for high printing quality. In this work, an optimal prediction model, constructed with the lumped element modeling(LEM) and the artificial bee colony(ABC) algorithm, was proposed to efficiently predict the combination of waveform parameters for obtaining the desired droplet properties. For acquiring higher simulation accuracy, a modified dynamic lumped element model(DLEM) was proposed with time-varying equivalent circuits, which can characterize the nonlinear behaviors of piezoelectric printhead. The proposed method was then applied to investigate the influences of various waveform parameters on droplet volume and velocity of nano-silver ink, and to predict the printing quality using nano-silver ink. Experimental results show that, compared with two-dimension manual search, the proposed optimal prediction model perform efficiently and accurately in searching the appropriate combination of waveform parameters for printable electronics fabrication.

Design of fuzzy adaptive washout algorithm based on the novel tilt coordinate

Motion simulator usually appears the phenomenon of false cues and the workspace is limited in the process of washout. The proposed washout algorithm combines fuzzy logic control with the vestibular system to design the tilt coordination fuzzy adaptive filter, in order to minimize the vestibular sensory error below the human perception threshold. Owing to tilt coordination angular velocity limiter, the loss of low-pass acceleration must be compensated by the acceleration transform model. The translational channel decreases the possibility of the workspace beyond limitation and expands the scope of motion platform simulating input acceleration by using third-order filter. The simulation results show that the proposed algorithm can effectively overcome the phase retardation of classical washout algorithm, and then prevent the produce of false cues, decrease the displacement of motion platform simultaneously; in addition, white Gaussian noise simulates large variations in acceleration. The proposed washout algorithm can have maximal extreme value of acceleration and accurate simulating performance in general. It also proves that the proposed washout algorithm has a strong adaptability and reliability, which can effectively improve the dynamic fidelity for motion simulator.

Development Trends in Additive Manufacturing and 3D Printing

Additive manufacturing and 3D printing tech-nology have been developing rapidly in the last 30 years, and indicate great potential for future development. The promising future of this technology makes its impact on traditional industry unpredictable. 3D printing will propel the revolution of fabrication modes forward, and bring in a new era for customized fabrication by realizing the five "any"s: use of almost any material to fabricate any part, in any quantity and any location, for any industrial field. Innovations in material, design, and fabrication processes will be inspired by the merging of 3D-printing technology and processes with traditional manufacturing processes. Finally, 3D printing will become as valuable for manufacturing industries as equivalent and subtractive manufacturing processes.

Calculation of impact factor of vibrator oscillation in offset printing based on fuzzy controller and genetic algorithm

In the inking system of an offset printing press,a vibrator roller distributes ink not only in the circumferential direction but also in the axial direction.In the control process,if ink amount is determined only by the dot area coverage without considering the impact of vibrator roller's oscillation,the printing colour quality will be reduced.This paper describes a method of calculating the impact factor of vibrator roller' s oscillation.First,the oscillation performance is analyzed and sample data of impact factor is got.Then,a fuzzy controller used for the calculation of the impact factor is designed,and genetic algorithm is used to optimize membership functions and obtain the fuzzy control rules automatically.This fuzzy controller can be used to calculate impact factors for any printing condition,and the impact factors can be used for ink amount control in printing process and it is important for higher printing colour quality and lowering ink and paper waste.

CFD-DEM simulation of fluid-solid flow of a tapered column separation bed

Research on recycling waste Printed Circuit Boards(PCB) is at the forefront of preventing environmental pollution and finding ways to recycle resources.The Tapered Column Separation Bed(TCSB) is invented aiming at disposing the problem that fine particles of waste printed circuit boards cannot be separated efficiently so as to obtain further insight about the underlying mechanisms and demonstrate the separation feasibility in the tapered column separation bed.In this work,a Computational Fluid Dynamics(CFD) coupled with Discrete Element Method(DEM) model for two-phase flow has been extended to simulate the fluid-solid flow in the tapered column separation bed.Its validity is demonstrated by its successful capturing the key features of particles' flow pattern,velocity,the pressure distribution,the axial position with time and axial force for particles with different densities.Simulation results show that the plastic particles and resin particles become overflow,while copper particles,iron particles and aluminum particles successively become underflow,with a discharge water flow rate of 1 m^3/h,an obliquity of 30°.The simulated results agree reasonably well with the experimental observation.Using this equipment to separate waste PCBs is feasible,theoretically.

The manifestation of texture art in the creative design of fashion fabrics

This paper presents a discussion of the characters and design patterns of the digital texture design in fashion fabrics. It starts from the characters of fabric texture design, taking digital printing technology as a detailed example, and raises a possible design route and pattern of the innovative design of fashion fabrics under digital technology.

雕

丰富多样的邮票天地中,雕刻版邮票以其制作工艺和印刷技术的复杂而著称。在手工雕版时代,雕刻版邮票要求雕刻师用钢刀在钢板上一刀一刀刻出印刷模版,用刀具将原作图案雕成印版图案。一块模版往往要经过几个月的雕琢,稍有不慎就将前功尽弃。随着科技的发展,印制技术的进步,如今的雕刻版邮票虽然加入了电脑处理,但就其印制方式来说,仍然是最为“麻烦”的一种。但正所谓“梅花香自苦寒来”,制作过程的繁复精细,造就了一枚枚方寸精品。雕刻版邮票自从诞生之日起,就以其凹凸的线条、精致的图案,带给人高贵典雅的视觉体验,成为无数集邮爱好者的“心头好”,也因其艺术与技术相结合的独特美感而备受收藏界的青睐。

Chinese brushes： From controllable liquid manipulation to template-free printing microlines

As a traditional writing instrument for calligraphy and painting, the Chinese brush has enjoyed a high reputation over the last 5,000 years due to its ability to controllably handle liquid ink, and has been widely used to deposit ink into certain characters or figures as a means of cultural communication. In this mini-review, we first show how the key to the controllable liquid transfer in a Chinese brush lies in the anisotropic multi-scale structural features of the freshly emergent hairs. Then, drawing inspiration from this, applications in controllable liquid pumping, highly efficient liquid transfer and template-free printing microlines are addressed. We envision that the fundamentals of Chinese brushes and their applications in liquid manipulation mentioned in this review may also be extended to other liquid phase functional material systems.

Large-area, kirigami topology structure-induced highly stretchable and flexible interconnects: Directly printing preparation and mechanic mechanism

Integrating the topology design and printing method offers a promising methodology to realize large stretchability for interconnects.Herein,eco-friendly and waterbased Ag nanowires(NWs)inks were formulated and used for screen-printing highly stretchable and flexible interconnects on a large area(more than 335 mm x 175 mm).The stretchability of the interconnects was realized by introducing kirigami topology structures.The topology designed models were established to simulate the influence of kirigami patterns on wire compliance and to estimate the maximum stretchability via finite element analysis(FEA).The mechanic mechanism results demonstrate that an increase of the wave numbers results in larger stretchability,and the rectangular type of wave shows better stretchability than the zigzag and sine structures.Comparatively,the electrical and mechanical properties of the interconnects were measured and analyzed,and the experimental results were consistent with FEA.The electric conductivity of the interconnects is stable at^10,427 S cm-1 even after 1000 cycles of 15.83 mm radius bending,280%stretching and 200%twisting-stretching deformation,demonstrating outstanding mechanical reliability of the interconnects.The topology designed interconnects have been applied in stretchable flexible light-emitting diode,indicating their broad application prospects in next-generation stretchable electronics.

Between Manuscript and Print： Literary Reception in Late Medieval France. The Case of the Songe de la Pucelle

Based on original archival and codicological research, this paper in- vestigates the transformations and negotiations between manuscript and printed versions of fifteenth-century poetry through the specific example of one surprisingly complex debate poem, Le Songe de la Pucelle （The Dream of the Virgin）. Our debate relates the choice that a female narrator must make between the respective appeals of two personifications, Love and Shame, who appear to her in a dream- vision. The manuscript tradition invariably collects the poem with other fifteenth- century debates and moral texts, while the early printed copies tended to have experienced a prior separate circulation and often remain as monotextual pamphlets. Manuscript and printed copies of the same poem seem, then, to target different audiences. My paper investigates this curious divergence in the transmission pattern of the manuscript and printed versions of the Songe and seeks possible answers in the very different sets of images accompanying the text in manuscript and printed versions.

Pulsed electrohydrodynamic printing of conductive silver patterns on demand

Pulsed electrohydrodynamic printing （EHDP） is used to fabricate conductive silver patterns with micrometer resolution. The silver ink pendant experiences swelling, pulsation, and ejection under an applied pulse voltage of 20 Hz. The droplet deposi- tion frequency is equal to the applied voltage frequency so that the EHDP can deposit silver ink on demand. A low applied voltage favors uniform and non-scattering silver patterns while a high applied voltage results in ink scattering. Discrete drop- lets with 45-55 gm in diameter and continuous tracks with 60 gm in width are generated by using a ll0-i.tm-cailber nozzle. The feature size of deposited patterns is about half of the nozzle caliber, and a finer resolution can be achieved with the intro- duction of smaller nozzle calibers. Furthermore, the appropriate curing condition is investigated for sufficient combustion of ink solvent. The minimum resistivity of 3.3 gf~ cm is demonstrated for a continuous track cured at 200~C for 10 min. Eventu- ally, several passive electrical components, such as coated resistors, interdigitated capacitors （6 pF）, and spiral inductors （0.6 gH）, are successfully fabricated.