Experiment and Research of EDM Surface Modification of Titanium in Mist Medium

2014 ◽  
Vol 538 ◽  
pp. 24-27 ◽  
Author(s):  
Xiao Jun Hu ◽  
Lan Rong Cai ◽  
Min Li ◽  
Wen Guo Huo
Keyword(s):  
Negative Polarity ◽  
Deionized Water ◽  
Pulse Interval ◽  
Tool Electrode ◽  
Current Pulse Duration ◽  
Fine Grained ◽  
Working Medium ◽  
Modification Of Titanium ◽  
Graphite Rod ◽  
A Current

By AF1100-type EDM machine, graphite rod as a tool electrode, misted deionized water mixed with fine-grained C powder as working medium, the strengthening coating was prepared on the surface of TC4 titanium. The surface microstructure of strengthening layer was observed, the hardness and thickness of strengthening layer was tested, under different peak current, pulse duration, pulse interval and polarity. The results show that: At a current of 2.9A to 6.6A when using negative polarity to strengthen can get better strengthening layer organizational.

scholarly journals Fine-Grained Power Gating Using an MRAM-CMOS Non-Volatile Flip-Flop

Micromachines ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 411 ◽  
Author(s):  
Jaeyoung Park ◽  
Young Yim
Keyword(s):  
Field Effect Transistor ◽  
Magnetic Tunnel Junction ◽  
Oxide Semiconductor ◽  
Pulse Modulation ◽  
Flip Flop ◽  
Fine Grained ◽  
Temporary Storage ◽  
Area Overhead ◽  
Effect Transistor ◽  
A Current

An area-efficient non-volatile flip flop (NVFF) is proposed. Two minimum-sized Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) and two magnetic tunnel junction (MTJ) devices are added on top of a conventional D flip-flop for temporary storage during the power-down. An area overhead of the temporary storage is minimized by reusing a part of the D flip-flop and an energy overhead is reduced by a current-reuse technique. In addition, two optimization strategies of the use of the proposed NVFF are proposed: (1) A module-based placement in a design phase for minimizing the area overhead; and (2) a dynamic write pulse modulation at runtime for reducing the energy overhead. We evaluated the proposed NVFF circuit using a compact MTJ model targeting an implementation in a 10 nm technology node. Results indicate that area overhead is 6.9 % normalized to the conventional flip flop. Compared to the best previously known NVFFs, the proposed circuit succeeded in reducing the area by 4.1 × and the energy by 1.5 × . The proposed placement strategy of the NVFF shows an improvement of nearly a factor of 2–18 in terms of area and energy, and the pulse duration modulation provides a further energy reduction depending on fault tolerance of programs.

Statistical Distributions of Lightning Parameters with Emphasis on their Extremely High Values

2021 ◽  
Vol 3 (3) ◽  
pp. 4-25
Author(s):  
Vladimir A. RAKOV ◽  
◽  
Evgeny A. MAREEV ◽  
Keyword(s):  
Extreme Values ◽  
Negative Polarity ◽  
Lightning Protection ◽  
Time Duration ◽  
Return Stroke ◽  
Lightning Channel ◽  
Direct Measurements ◽  
Analysis Of Results ◽  
Wide Scatter ◽  
A Current

The paper is devoted to the review of the data on the lightning parameters necessary for development and perfection of lightning protection systems. It is shown, that down to present time national and international lightning protection standards are based on the Berger’s data on distribution of lightning amplitudes currents. Experimental data on amplitude of the return-stroke current the received recently in Brazil, Japan, USA (Florida) and Austria are resulted. It is emphasized, that the given data on currents of a lightning are characterized by a wide scatter that specifies necessity of realization of the further researches. The detailed description of parameters of the return-stroke peak current, including duration of front time, duration of a pulse, a steepness of a current at the front is given. It is emphasized, that median value of amplitude of a current of the first making the return-stroke in 3-4 times is higher than a current of the subsequent components. The analysis measured median (50%) and severe (1%) values of lighting parameters which are necessary for construction of a curve of distribution in the assumption of its submission lognormal law is carried out. Results of theoretical researches are given according to extreme values of currents of a lightning. It is shown, that, depending on length of the lightning channel (from 4 up to 6 kms), the maximal current can vary from 300 kA up to 500 кА. The minimal value of lightning current is appreciated in 2 кА. The analysis of results of new direct measurements has shown, that for a lightning of positive polarity the maximal current can reach 340 кА, that appreciably is higher than a settlement maximum for a lightning of negative polarity (200 кА). Recent theoretical researches have allowed to prove experimentally received lognormal distribution of currents for lightning of negative polarity.

“Too many Americans are trapped in fear, violence and poverty”: a psychology-informed sentiment analysis of campaign speeches from the 2016 US Presidential Election

2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Thomas Hoffmann
Keyword(s):  
New York ◽  
Sentiment Analysis ◽  
Presidential Election ◽  
Negative Polarity ◽  
Psychological Research ◽  
Crowd Sourcing ◽  
Fine Grained ◽  
Campaign Speeches ◽  
Us Presidential Election

AbstractMost automatic sentiment analyses of texts tend to only employ a simple positive-negative polarity to classify emotions. In this paper, I illustrate a more fine-grained automatic sentiment analysis [Jockers, Matthew. 2016. Introduction to the Syuzhet package. https://cran.r-project.org/web/packages/syuzhet/vignettes/syuzhet-vignette.html (accessed 07 March 2017).; Mohammad, Saif M. & Peter D. Turney. 2013. Crowd sourcing a word-emotion association lexicon. Computational Intelligence 29(3). 436–465.] that is based on a classification of human emotions that has been put forward by psychological research [Plutchik, Robert. 1994. The psychology and biology of emotion. New York, NY: HarperCollins College Publishers.]. The advantages of this approach are illustrated by a sample study that analyses the emotional sentiment of the campaign speeches of the two main candidates of the 2016 US presidential election.

Investigation on the Influence of Machining Fluid on Processing Characteristics in Micro-EDM

2012 ◽  
Vol 479-481 ◽  
pp. 407-413 ◽  
Author(s):  
Sha Li ◽  
Wataru Natsu ◽  
Takeshi Masaki ◽  
Zu Yuan Yu
Keyword(s):  
Feed Rate ◽  
Deionized Water ◽  
Tool Electrode ◽  
Electrode Wear ◽  
Micro Edm ◽  
Machining Speed ◽  
Small Electrode ◽  
Short Circuits ◽  
Edm Drilling

In this paper the influence of machining liquid on the processing characteristics, such as the tool electrode wear and the tool actual feed were discussed. Micro EDM drilling was carried out using deionized water and oil dielectric as the machining liquid. It was found that using deionized water reduced the tool electrode wear. Also, occurrence of short-circuits during the processing is one of the reasons for causing large electrode wear. In the case of using oil dielectric, processed depth influences the tool electrode wear greatly and causes the change in the actual feed rate. While using deionized water, processed depth also causes the change in the actual feed rate, but nearly had no influence on the tool electrode wear. Meanwhile, when using deionized water, although the small electrode wear and high machining speed can be obtained, electrolytic dissolution may occur. Therefore, the effective method of decreasing the open voltage and increasing the feed rate to prevent the electrolytic dissolution was mentioned and experimentally verified.

A current-controlled flash sintering processing leading to dense and fine-grained typical multi-element ZnO varistor ceramics

2021 ◽  
pp. 160124
Author(s):  
Jingpeng Niu ◽  
Haibo She ◽  
Zhiyuan Liu ◽  
Muwen Cheng ◽  
Jingrong Xu ◽  
...  
Keyword(s):  
Fine Grained ◽  
Zno Varistor ◽  
Flash Sintering ◽  
A Current

Disordering and phase decomposition of a nickel-aluminum intermetallic under lowtemperature electron irradiation

1988 ◽  
Vol 46 ◽  
pp. 774-775
Author(s):  
E. A. Kenik ◽  
M. Nastasi
Keyword(s):  
Room Temperature ◽  
Ion Irradiation ◽  
Deionized Water ◽  
Appreciable Amount ◽  
Nickel Aluminum ◽  
Phase Decomposition ◽  
Multilayered Films ◽  
Fine Grained ◽  
20 Nm

In situ electron irradiations at 300 and 1000 kV have been performed at 100 and 300 K on Ni2Al3 for comparison with its response under ion irradiation. In addition, the behavior of Ni2Al3 will be compared to that of NiAl3 reported previously. Thin multilayered films of alternating nickel and aluminum were electron beam deposited onto a NaCl substrate. The substrate was dissolved in deionized water and the Ni/Al film was mounted on 3 mm diam grids. The films were vacuum annealed for 1—2 h at 623 K to allow interdiffusion between the layers. Electron diffraction indicated that the films were fine-grained (∼20 nm diam) Ni2Al3, which is the prototype for the hexagonal D513 structure. No appreciable amount of other phases was detected.The specimens were irradiated with 1000 kV electrons in a Hitachi HU-1000B or with 200—300 kV electrons in Philips EM430 and CM30 microscopes. All three microscopes are equipped for nominal room temperature or low temperature (∼100 K) irradiations.

Origin of Convoluted Laminae

1960 ◽  
Vol 97 (5) ◽  
pp. 409-421 ◽  
Author(s):  
John E Sanders
Keyword(s):  
Current Velocity ◽  
Cohesive Sediment ◽  
Bottom Relief ◽  
Shearing Stress ◽  
Current Passing ◽  
Fine Grained ◽  
New Interpretation ◽  
Sediment Bottom ◽  
Current Ripple ◽  
A Current

AbstractComparison of streaked-out “ripples” formed by the drag effects of a current passing over a watery, yet cohesive sediment bottom with convoluted laminae formed within beds of fine-grained sandstone suggests a common origin. Application of Bagnold's recent discoveries on the behaviour of cohesionless sediment in flowing fluids to the problem results in a modification of Kuenen's hypothesis of origin of the convolutions. According to the new interpretation, convolutions arise when formerly cohesionless sand grains become cohesive after deposition and respond to increased shearing due to higher current velocity by a décollementtype of adjustment with the plane or planes of adjustment located within, or in some cases at or below the base of the growing sandstone bed. Convolute “anticlines” in cohesive sand are thought to serve the same function as that played by current ripple-marks in cohesionless sand, i.e., they create additional bottom relief in order to increase the drag and restore equilibrium to the added shearing stress imposed by the current that cannot be counterbalanced by grain-to-grain encounters.

Micro-Forming Process and Microstructure of Deposit by Using Micro EDM Deposition in Air

2008 ◽  
Vol 375-376 ◽  
pp. 153-157 ◽  
Author(s):  
Zi Long Peng ◽  
Zhen Long Wang ◽  
Bai Dong Jin
Keyword(s):  
High Speed ◽  
Pulse Generator ◽  
Electrical Discharge Machining ◽  
High Speed Steel ◽  
Solidification Process ◽  
Pulse Interval ◽  
Tool Electrode ◽  
Micro Edm ◽  
Forming Process ◽  
Long Pulse

Based on analysis of the mechanism of Electrical Discharge Machining (EDM) and the characteristics of deposition processing, the processing conditions of micro EDM Deposition (micro EDD) are determined. Micro EDD is a new EDM method taking air as machining medium, using narrow pulse width, long pulse interval, low discharge current and connecting the tool electrode with the anode of pulse generator. Using EDM shaping machine and brass, tungsten and steel as tool electrode respectively, micro cylinders are deposited on high-speed steel surface. And then the microstructure of deposit is analyzed detailedly. Results show that elements of the deposited material distribute uniformly, whose components depend on the tool electrode material. As the high cooling rate of the solidification process, the deposit grain size refines obviously, which leads to the hardness of tungsten or steel deposit increasing. Moreover, the Metallurgical bonding has occurred on the interface between deposit and high-speed steel base, whose thickness is about 5μm.

scholarly journals The potentiality of sinking EDM for micro-impressions on Ti-6Al-4V: keeping the geometrical errors (axial and radial) and other machining measures (tool erosion and work roughness) at minimum

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Naveed Ahmed ◽  
Saqib Anwar ◽  
Kashif Ishfaq ◽  
Madiha Rafaqat ◽  
Mustafa Saleh ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Electrode Materials ◽  
Dimensional Accuracy ◽  
Negative Polarity ◽  
Copper Electrode ◽  
Tool Electrode ◽  
Dimensional Error ◽  
Industrial Sectors ◽  
Response Measures ◽  
Length Reduction

AbstractTi-6Al-4V is a material of high interest in various industrial sectors including biomedical, automotive and aerospace. Conventional means of machining encounter different types of difficulties. Electric discharge machining (EDM) is not a contest of hardness. Circular impressions of micro-depth are produced in Ti-6Al-4V using four different electrode materials including aluminum, brass, graphite and copper, each assigned positive and negative polarity. In order to get precise control over the geometry of micro-impressions dimensional accuracy and tool wear must be controlled. Thus, EDM performance has been evaluated in terms of axial dimensional error (D.E_Axi), radial dimensional error (D.E_Rad), tool length reduction (TLR), and surface roughness (SR). Since the EDM process is stochastic in nature therefore in addition to tool polarity only two factors are considered as variables, i.e. discharge current and pulse-time-ratio (ration of on-time to off-time). The behaviors of each of the four electrode materials are compared together under each of the two polarities and two variables for each of the four response characteristics. The search is carried out to select the most appropriate tool electrode polarity (common for all responses) and a single common electrode capable of minimizing all the four response measures simultaneously. Moreover, microstructures of the machined impressions are discussed. Without any compromise in the minimum values of response measures, no single polarity and a single electrode are found common. However, with a slight compromise over the machining measures negative tool polarity and copper electrode served the purpose of set objectives (minimum of D.E, TLR, and SR). The expanse of compromise is found to be ≤ 50 µm in axial and radial dimensional errors, 0.8 µm in surface roughness and no compromise in tool length reduction if the copper electrode is assigned with negative polarity.

scholarly journals Charging Platform of Chess-Pad Configuration for Unmanned Aerial Vehicle (UAV)

2020 ◽  
Vol 10 (23) ◽  
pp. 8365
Author(s):  
Mohammed Rameez Al-Obaidi ◽  
Wan Zuha Wan Hasan ◽  
Mohd Amrallah Mustafa ◽  
Norhafiz Azis
Keyword(s):  
Energy Conversion ◽  
Contact Point ◽  
Design Procedure ◽  
Negative Polarity ◽  
Scheme Design ◽  
Bridge Rectifier ◽  
Reliable Performance ◽  
Aerial Vehicle ◽  
Process Energy ◽  
A Current

The authors of this study designed and optimized a charging landing pad system that mitigates the landing accuracy issues of unmanned aerial vehicles (UAVs). The study looks at the charging process, energy conversion during periodic landing on a unique platform, and an onboard and on-ground scheme design procedure. The circuit is fixed on the UAV platform and comprises six integrated bridge rectifier diodes to alter the four connection pin terminals’ charge polarity. The inclusion of a current indicator shows the flow of charge during successful docking. The charging platform consists of square conductive copper plates of specific dimensions that provide positive and negative polarity in a chess form to ensure the contact of various polarities. This design considers two power supply options: a solar panel and a standard mains supply. The contact point coordinate probability when landing is the crucial aspect of this design. A first version of the proposed system was implemented to measure its effectiveness for commercial drones. This system provides an automated recharge station with reliable performance. Numerical experiments showed that the system’s energy conversion remains efficient regardless of drone orientation over the platform or the environment’s nature.

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