Calculation of negative-pressure chip in suction-type internal chip removal system and analysis of influencing factors

Compacted graphite iron (CGI) is considered as the ideal material to make modern fuel-efficient diesel engine. Due to the vermicular or worm-like graphite distributed among the ferrite/pearlite matrix, CGI behaves better physical and mechanical properties in comparison with gray cast iron (GCI) and spherical graphite spheroidal cast iron (SGI). However, these good properties bring about the machining challenges. So it is important to appropriately select cutting parameters to machine this material with economy and efficiency. The present study investigated the influence of cutting parameters, such as cutting speed V, feed rate f, and exit angle Ψ, on workpiece material removal volume Q and cutting burr height on the entrance side H₁ and on the exit side H₂ during high-speed milling of CGI by the coated carbide tools_. On this basis, the relatively optimum high-speed cutting parameters were selected under the research condition. Cutting tool failure mechanism was also investigated with the aid of scanning electronic microscope (SEM) and energy-dispersive system (EDS) (SUPRA55, Germany) analysis. The results showed that Q, H₁, H₂, and the type of cutting burr on the exit side of the machined surface could be influenced by the cutting parameters. And the relatively optimum cutting parameters are V = 800 m/min, f = 0.25 mm/rev, and Ψ = 60°. Adhesive wear and thermal cracks which were perpendicular to the cutting edge were common wear mechanisms during the cutting process. However, with an increase in feed rate, mechanical cracks which were parallel to the cutting edge could be found on the flank face of the cutting tool.     

Theoretical investigation on nanoparticle concentrations in optoelectrofluidic chip based on diffusion,convection, and migration

A numerical model and simulation relative to an optoelectrofluidic chip has been presented in this article. Both dielectrophoretic and electroosmotic force attracting the nano-sized particles could be studied by the diffusion, convection, and migration equations. For the nano-sized particles, the protein with radius 3.6?nm is considered as the objective particle. The electroosmosis dependent upon applied frequency is calculated, which range 10²?Hz from 10⁸?Hz, and provides the much stronger force to enrich proteins than dielectrophoresis (DEP). Meanwhile, the induced light pattern size significantly affecting the concentration distribution is simulated. In this end, the concentration curve has verified that the optoelectrofluidic chip can be capable of manipulating and assembling the suspended submicron particles.     

具有三维聚焦功能的微流控芯片

为了使用微流体细胞仪对细胞精确计数,采用紫外光刻工艺制作了能够真正实现三维聚焦功能的微流体检测芯片(微流控芯片).使用聚二甲基硅氧烷(PDMS)进行二次倒模复制其结构以缩短微流控芯片制作周期、降低制作成本,并进行了芯片的封装与测试.首先,利用沉浸式光刻技术和斜曝光工艺制作了具有三维聚焦功能的SU-8微流沟道;然后,利用PDMS对所制作的SU-8微流沟道进行一次倒模,得到其负模结构;对负模结构进行表面处理后,再进行二次倒模,得到PDMS微流沟道;最后,封装PDMS微流沟道与盖片,制得微流控芯片,并对微流控芯片的沟道聚焦效果进行了测试.实验测试发现随着鞘流与样本流流速比不同,得到样本流的聚焦宽度也不同.当鞘流与样本流流速比为20∶1时,可以得到约10.4 μm的聚焦宽度.结果表明,该芯片结构可靠,可以满足进一步的流体聚焦检测要求.采用该方法制作的微流控芯片具有生产周期短、成本低、效率高和结构可靠的特点.     

Microfluidic on chip viscometers

We present the design and the process of fabrication of micromachined capillary on chip rheometers which have performed wall shear stress and shear rate measurements on silicon oil and ethanol-based nanofluids. The originality of these devices comes from the fact that local pressure drop measurements are performed inside the microchannels. Thus, the advantage over existing microviscometers is that they can be used with the fluid under test alone; no reference fluid nor posttreatment of the data are needed. Each on chip viscometer consists of anodically bonded silicon-Pyrex derivative microchannels equipped with local probes. The anodic bonding allows to reach relatively high pressure levels (up to approximately 10 bars) in the channels, and a broad range of shear stress and shear rate values is attainable. Dielectrophoretic and electrorheological effects can be highlighted by employing alternate microstripe electrodes patterned onto the inner side of the Pyrex wall.     

嵌入式神经网络加速器及SoC芯片

为了提高人工智能加速器的运算效率和功耗效率,提出了一种新的卷积神经网络(CNN)加速器结构,并实现了神经网络存算一体的方法。首先,设计出一种神经网络架构,其具有高度并行计算以及乘加器(MAC)单元高效运行的特性。其次,为了降低功耗和面积,采用了对称的静态随机存储器(SRAM)阵列和可调数据流向结构,实现多层网络在SRAM中高效计算,减少了访问外部存储器次数,降低了功耗,提高运算效率。通过中芯国际40 nm工艺,完成了系统芯片(SoC)设计、流片与测试。结果表明运算速度在500 MHz下,算力可达288 GOPS;全速运行功耗89.4 mW;面积1.514 mm²;算力功耗比3.22 TOPS/W;40 nm算力面积比为95.1 GOPS/mm²。与已有文献的相比,算力功耗至少提升4.54%,算力面积至少提升134%,对于嵌入式场景应用较适合。     

Quantum-mechanical modeling of chip deformation and failure

An atomic approach to chip deformation and failure in cutting is outlined. The relation of the shear strength and the type of chip to the energy characteristics of the crystal lattice, its packing-defect energy, and the latent heat of fusion is established. The constancy of the shear with variation in the cutting conditions is related to the limiting dislocation density and the formation of an amorphous–liquid state.     

利用MODEM芯片实现单片机远程通讯

介绍了利用MODEM芯片实现单片机远程通讯。着重分析73K222AL芯片的结构特征，设计出MODEM芯片与AT89051的接口电路，并给出BELL 103协议下通讯呼叫连接过程的部分程序。     

微流控芯片二维电泳分离分析系统研究进展

微流控芯片分析系统(微全分析系统)近年来发展迅速,已经被应用于生物、环境样品的分离分析研究。多维分析系统能够极大地提高峰容量,适合于复杂样品体系的分离分析。在微流控芯片上进行的分离操作不仅可以有效地实现两种分离模式之间的零死体积切换,而且能够使分析速度与峰容量的矛盾得到补偿。本文对微流控芯片二维电泳分离分析系统的近期发展作综述,并展望其可能的发展前景。     

一种微流控检测芯片的设计与工艺研究

设计并制作了一种PMMA材料的微流控检测芯片,利用外界气体驱动液体,用于实验样品的分析和检测.芯片的整体尺寸为86 mm×60 mm×4.5 mm,利用精密加工的方法进行加工.采用一种简单实用的溶胶.凝胶改性方法对微通道管路进行亲水处理,实验证明亲水性有明显提高.并分析了亲水性提高的机理.提出一种新的溶剂键合方法,在室温下对芯片进行键合.溶剂为二氯乙烷和无水乙醇按1:1混合的混合液.分析了不同溶液配比、键合时间和键合压力对键合效果的影响.同时,芯片上集成了多个阀,对阀膜材料的选择、粘接工艺进行了研究.     

Development of electrorheological chip and conducting polymer-based sensor

This paper presents the development of an integrated sensor using two types of smart materials: electrorheological (ER) fluids and conducting polymers (CPs). The developed ER chip worked as an actuator, and it was driven by different voltages and control frequencies. When the four electrodes are controlled synchronously, the diaphragm acts as a vibrator whose frequency can be adjusted in accordance with the frequency of the electrical signals. The response signals of the CP sensor were recorded, and its properties were analyzed. Experimental results show that the amplitude decreases monotonically when the frequency increases, owing to the time delay in the pressure buildup in the ER chip. However, the displacement fluctuation of the diaphragm below 20 Hz can be detected clearly even if the value is very low. When the vibration frequency is larger than 20 Hz, the CP sensor can hardly detect the displacement fluctuation. Thus, the upper limit frequency that the CP sensor can detect is about 20 Hz. The practical applications of this microdevice are also discussed.     

Development of electrorheological chip and conducting polymer-based sensor

This paper presents the development of an integrated sensor using two types of smart materials: electrorheological (ER) fluids and conducting polymers (CPs). The developed ER chip worked as an actuator, and it was driven by different voltages and control frequencies. When the four electrodes are controlled synchronously, the diaphragm acts as a vibrator whose frequency can be adjusted in accordance with the frequency of the electrical signals. The response signals of the CP sensor were recorded, and its properties were analyzed. Experimental results show that the amplitude decreases monotonically when the frequency increases, owing to the time delay in the pressure buildup in the ER chip. However, the displacement fluctuation of the diaphragm below 20Hz can be detected clearly even if the value is very low. When the vibration frequency is larger than 20Hz, the CP sensor can hardly detect the displacement fluctuation. Thus, the upper limit frequency that the CP sensor can detect is about 20Hz. The practical applications of this microdevice are also discussed.     

自组织芯片设计和映射问题的研究

信息处理算法到芯片的映射是大规模集成电路设计的焦点问题.借助硬件进化(evolvable hardware,EHW)的工作机理,本文研究了另一种全新的信息处理算法的自组织映射方法.考虑到信息处理算法的多样性,以及算法映射对学习机制在数据构造问题上的不同针对性,本文从自适应无损图像压缩硬件实现这一典型的问题出发来考虑和研究算法映射的关键问题.分析指出了现有EHW工作模型存在的不足,提出并探讨了适应度评估机制的计算复杂性、模型的可扩展性以及模型的可移植性3个关键问题,并给出了针对性的解决方案.     

蛋白芯片技术研究进展及其应用

蛋白芯片技术作为进行生命科学研究的一种新的技术平台 ,日益受到人们的关注。目前这一技术已经应用于基因表达分析、单核苷酸多态性分析、基因突变检测、抗体筛选及临床诊断等许多领域。随着该技术的不断完善 ,它将在生命科学研究中发挥越来越重要的作用。本文就蛋白芯片的原理、分类、制备过程、研究进展、优缺点和发展前景作一介绍。     

3D metal removal simulation to determine uncut chip thickness, contact length, and surface finish in grinding

The two most important geometric parameters that describe the mechanics of grinding are the uncut chip thickness and the contact length. Currently, analytical approaches are used to estimate these parameters. The accuracy of these approaches, however, is limited because they do not take into account the random shape, size, and protrusion height and placement of the abrasive grains around the circumference of the grinding wheel. In this paper, a simulation technique was used to gain new insight into the effect of the stochastic nature of grinding wheels on the geometric properties of the grinding process. The simulator was used to calculate the number of active grains, uncut chip thickness, and contact length for a stochastic wheel model of Radiac Abrasive’s WRA-60-J5-V1 grinding wheel. These values were then mapped to every grain on the grinding wheel and used to determine the instantaneous material removal rate of the wheel and workpiece surface finish. There was excellent agreement between the predicted and experimentally measured surface topology of the workpiece. The results suggest that only 10–25 % of the grains on the grinding wheel are active and that the average grinding chip may be as much as ten times thicker and ten times shorter than would be produced by a grinding wheel with a regular arrangement of cutting edges as assumed by existing analytical approaches.     

Tool wear, chip formation and workpiece surface issues in CBN hard turning: A review

Steel parts that carry critical loads in everything from automotive drive trains and jet engines to industrial bearings and metal-forming machinery are normally produced by a series of processes, including time-consuming and costly grinding and polishing operations. Due to the advent of super-hard materials such as polycrystalline cubic boron nitride (PCBN) cutting tools and improved machine tool designs, hard turning has become an attractive alternative to grinding for steel parts. The potential of hard turning to eliminate the costs associated with additional finishing processes in conventional machining is appealing to industry. The objective of this paper, is to survey the recent research progress in hard turning with CBN tools in regard of tool wear, surface issues and chip formation. A significant pool of CBN turning studies has been surveyed in an attempt to achieve better understanding of tool wear, chip formation, surface finish, white layer formation, micro-hardness variation and residual stress on the basis of varying CBN content, binder, tool edge geometry, cooling methods and cutting parameters. Further important modeling techniques based on finite element, soft computing and other mathematical approaches used in CBN turning are reviewed. In conclusion, a summary of the CBN turning and modeling techniques is outlined and the scope of future work is presented.     

DNA芯片的CCD荧光检测

为了有效地提取DNA芯片的信息,叙述了DNA芯片的CCD荧光检测的原理及自行设计的检测系统。系统由CCD摄像机、荧光成像光学系统、图像采集卡等组成。利用高压汞灯作为光源,窄带滤色片作为激发波段和荧光截止滤波片,从而保证荧光分辨力和测量范围。通过CCD摄像机和图像采集卡进行图像采集,并对获取的图像进行处理。试验结果有效地获得了杂交后基因点位的关键特征的数据。     

Modeling chip formation with grooved tools

A slip-line field model for orthogonal cutting with a tool containing a groove-like feature on its rake face is proposed. Primary contact at the tool-chip interface is taken to be plastic. Based on experimental observations, it is assumed that the chip flows into the groove, and is forced to curl by Coulomb friction contact with the groove back wall. Solutions obtained for different groove geometries, groove positions relative to the cutting edge, rake angles and tool-chip interface friction using the matrix operator method are presented and discussed. The calculated results are in general agreement with experimental observations. It is found that the model can be formulated so that it can be used to predict the cutting geometry for obstruction-type chip breakers as well.