Ampere Range Research Articles

Economic heavy minerals in the stream sediments of wadi Shaàb, southern coast of the Red Sea, Egypt; characterization and upgrading for investigation of their potential recovery

The southern coast of the Red Sea is one of the most promising areas for the occurrence of economic minerals. Therefore, studying the characterization and evaluation of these minerals in the Wadi Shaàb Quaternary sediments and investigating their ability to concentrate and physically separate using economical and ecofriendly techniques is the main goal of this work. The results showed that the representative sample contains an average of 0.06% ilmenite, 0.08% zircon, 0.07% rutile, 0.07% leucoxene, 0.008% cassiterite, 0.004% xenotime, 0.0004% monazite, 0.022% almandine garnet, and 0.46% magnetite. The recovery of economic heavy minerals was applied using a combination of wet-gravity technique via shaking table and magnetic separation using high intensity magnetic separator. The results demonstrated the success of gravity separation in raising the grade from 7.63% to 45.03% in a yield of 13.74% out of the original sample, and also valuable metallurgical recoveries that greater than 89% for tabling multi-stages (rougher and scavenging) was obtained. Concentrated mineral fractions of magnetite, ilmenite, almandine, heavy silicates, and the non-magnetic fraction bearing zircon and rutile were obtained using a high intensity magnetic separator at different ampere range

Hybrid Cathode Lithium Battery Discharge Simulation for Implantable Cardioverter Defibrillators Using a Coupled Electro-Thermal Dynamic Model.

This paper explores the effect of the load imposed by implantable cardioverter defibrillators (ICDs) on their lithium battery power sources longevity using a simulation approach that incorporates a coupled electro-thermal dynamic model. ICDs are one of the effective treatments available to significantly improve survival of patients with fatal arrhythmia (abnormal heart rhythm) disorders. Using a lithium battery power source, this life-saving device sends electrical shocks or pulses to regulate the heartbeat. The service life and reliability of an ICD is primarily expressed by its battery's lifespan and performance. In this paper we investigate the terminal voltage, depth of discharge and temperature dynamics of the implantable lithium battery with a combined cathode material, namely silver vanadium oxide and carbon-monofluoride (Li/SVO-CFx). Modeling the implantable batteries characteristics is a well-established topic in literature; however, to the best of the author's knowledge, the impact of the high-energy shocks (defibrillation) and low-energy device power supply (housekeeping) on the ICD's battery operation is relatively less-explored. Our analysis reveals that the battery terminal voltage is primarily influenced by the continuous low-level housekeeping discharge current within the range of micro amps, rather than the intermittent high-level demand of defibrillation current within the range of several amperes. A Monte Carlo simulation and model prediction comparison with real-time experimental data from literature were used to assess the accuracy and applicability of the model. The results can be used to improve the device battery design, control and operation, thus extending the service life in patients and reducing the need for invasive replacement surgery.

Design Low Noise Voltage Amplifier for Hand-Held Electronic Reader

There are limited number of electrical based two type electrode electronic readers for biosensors are commercial available because of the noise issues and amplification at nano to pico ampere current range. This research is mainly focused on designing an active low pass filter circuit of electronic reader for biosensors. The entire circuits are comprised of a voltage converter circuit, active low pass filter circuit, voltage amplifier, microcontroller and display unit. The circuit capture, filter and amplify nano and pico ampere current convert it to detectable voltage range as an output signal to the processing circuit. NodeMCU was act as the process and control circuit to read the output voltage from the amplifier circuit. The signal generator will act as a replacement for the biosensor input current and oscilloscope will display the input and output signal. The Design Spark PCB software was used to design the voltage amplifier circuit. Arduino software was used to create a programming code to upload in NodeMCU microcontroller.

Design 5.0 µm Gap Aluminium Interdigitated Electrode for Sensitive pH Detection

The aim of the research study to design high sensitive biosensor for medical applications. IDE pattern was designed using AutoCAD software with 5 µm ginger gap. The fabrication process was done using a conventional photolithography process and standard CMOS process. The fabricated electrode was physically characterized using a low power microscope (LPM) and a high power microscope (HPM). The electrically validated through I-V measurements and chemically tested with different pH buffer solutions. Al IDE was well fabricated with 0.1 µm tolerance between the design mask and fabricated IDEs. Electrical measurements confirmed that IDE was well fabricated without any shortage and results of similar IDE samples were confirmed that the repeatability of the device. The extremely small current variations in nano ampere range were quantitatively detected using an extra small volume of 2 µl for different pH buffer solutions. It is confirmed that IDEs are sensitive in both alkali and hydroxyl ions medium.

The Influence of Welding Ampere Range to ST-40 Shear Strength with Butt Joint

This experiment was conducted on the influence of welding process with ampere range variation and weld joints toward ST-40 shear strength. Furthermore, welded specimen is tested with tensile test. Method of this experiment is testing shear strength by using tensile testing machine where each five-specimens were previously welded by ampere range of 80 A, 90 A, and 100 A. Shear results show the highest shear strength is on 128.4916 N/mm2 with 80-ampere range on specimen no. 5, while on 90-ampere range variation the highest shear strength is on 124.7528 N/mm2, the specimen no. 5. Meanwhile, on 100-ampere range variation, the highest shear strength is on 120.1484 N/mm2, the specimen no. 4. The higher ampere (I) used, the higher heat (Q) resulted. When the heat increases, the welding electrode is perfectly fused. It makes good welding result achieved. The more strength on welding result, the higher shear strength (τ) achieved. On the other hand, the higher ampere range on welding process results higher shear strength.

Optimization of maximum tensile strength of welded joints of API 5L X65 pipes by Taguchi method

In this study, the joint performance of API 5L X65 steel pipes welded using shielded metal arc welding method was examined using the Taguchi method. As performance indicators, strength of current, welding direction, and electrode type were considered as input parameters, and the maximum tensile strength of the welded samples was considered as the output parameter. The optimum input parameters were determined to be ‘cellulosic electrode,’ ‘upward direction,’ and ‘150–180 Ampere range strength of current’. In the optimization process, it was observed that the difference between the maximum tensile strength results obtained from the experiments and the estimated results was insignificant. Thus, it is assumed that this difference can be neglected. Consequently, we concluded that Taguchi optimization can be applied successfully to the estimation of maximum tensile strength.

RF performance enhancement in multi-fin TFETs by scaling inter fin separation

This paper deals with the extraction of RF metrics of multi-fin Tunnel FET (TFET) with the inter fin separation (IFS) scaled up to 1nm. The structure of multi-fin TFET is designed by varying the number of fins (N) from 1 to 5. As the number of fins increases, the drive current (ID) gets multiplied and the maximum ID of 76µA can be achieved for N = 5. Higher ID is obtained without compromising the leakage current (IOFF) which is in the range of femto amperes. For the various values of IFS, RF metrics such as intrinsic gain (A0), unity gain cut-off frequency (ft), maximum oscillation frequency (fmax), and admittance (Y) parameters are extracted for multi-fin TFETs. The results show for lesser values of IFS, higher intrinsic gain is obtained and the value does not affect as N increases. The maximum value of ft and fmax is obtained because of the electrostatic coupling between the two adjacent fins. The Y parameters are extracted at an operating frequency of 10GHz. It can be seen that Y parameters offer better values as the number of fins and IFS increases. This is due to the larger value of gate to drain capacitance (Cgd) which occurs because of the parasitic effect for higher values of IFS.

Design, fabrication and characterization of 1.0 μm Gap Al based interdigitated electrode for biosensors

Interdigitated electrode (IDE) based electrical biosensors are promising in the medical application field. The aim of the research study is design, fabricate and characterize of low cost, high sensitive biosensor for medical applications. IDE pattern was designed using AutoCAD software with 1 μm finger gap. Fabrication process was done using conventional photolithography process and standard CMOS process. Fabricated electrode was physically characterized using SEM images, electrically validated through I–V measurements and chemically tested with different pH buffer solutions. Al IDE was well fabricated with 0.1 μm tolerance between design mask and fabricated IDEs. Electrical measurements confirmed that IDE was well fabricated without any shortage and results of similar IDE samples were confirmed that the repeatability of the device. The extremely small current variations in nano ampere range were quantitatively detected using extra small volume of 1 μl for different pH buffer solutions. It is confirmed that IDEs are sensitive in both alkali and hydroxyl ions medium.

A New Analytical Model for Improving Sub-Threshold Conduction of MOSFETs

In this paper, an analytical model representing a long channel MOSFET structure with larger effective channel thickness is proposed which reduces sub-threshold current to pico ampere level. The effective depletion channel thickness is calculated and utilized to find a mathematical expression for sub-threshold current. At first, the equation of a tangent is drawn at surface potential of potential vs. depletion depth curve. The equation of the tangent is derived from solving 1-D Poisson’s equation at SiO2-Si interface. The intersection of tangent with the horizontal axis is assumed as the new effective channel thickness of sub-threshold conduction channel. Further inclusion of gate voltage shifts due to interfacial traps, mobile ions and fixed ions modifies the derived equation and increases the magnitude of sub-threshold current to nano ampere range. This proposed model substantially lowers sub-threshold current in MOSFET than previous models predicted.

Anomalous Currents in Low Voltage Polymer Tantalum Capacitors

Low voltage Polymer Ta capacitors fabricated with porous Ta anodes, anodic oxide films of Ta as a dielectric, and poly(3,4-ethylenedioxythiophene) (PEDOT) cathodes were investigated. The polymer cathodes were formed by either pure in-situ polymerization or hybrid polymerization, with in-situ PEDOT inside the porous anodes and a pre-polymerized PEDOT cathode on the external surface of the anodes. Anomalous transient current, DC leakage, and breakdown voltage were observed and investigated at normal and reverse polarities in a broad range of temperatures and voltages. Anomalously high transient current in the ampere range was observed when a pulse of rated voltage at normal polarity (+ on the Ta anode) was applied to the capacitors, and anomalous DC current was observed when rated voltage was applied at low temperature. This effect was significantly more pronounced in the hybrid devices, but significantly decreased in all cases with humidification. The anomalous currents were explained by the presence of dipoles, charged polymer chains, in the conducting polymer cathode at its interface with the dielectric.

Fluctuation Tolerant Charge-Integration Read Scheme for Ultrafast DNA Sequencing with Nanopore Device

A charge-integration read scheme has been developed for a solid-nanopore DNA-sequencer that determines a genome by direct and electrical measurements of transverse tunneling current in single-stranded DNA. The magnitude of the current was simulated with a first-principles molecular dynamics method. It was found that the magnitude is as small as in the sub-pico ampere range, and signals from four bases represent wide distributions with overlaps between each base. The distribution is believed to originate with translational and rotational motion of DNA in a nanopore with a frequency of over 105Hz. A sequence scheme is presented to distinguish the distributed signals. The scheme makes widely distributed signals time-integrated convergent by cumulating charge at the capacitance of a nanopore device and read circuits. We estimated that an integration time of 1.4ms is sufficient to obtain a signal difference of over 10mV for distinguishing between each DNA base. Moreover, the time is shortened if paired bases, such as A-T and C-G in double-stranded DNA, can be measured simultaneously with two nanopores. Circuit simulations, which included the capacitance of a nanopore calculated with a device simulator, successfully distinguished between DNA bases in less than 2.0ms. The speed is roughly six orders faster than that of a conventional DNA sequencer. It is possible to determine the human genome in one day if 100-nanopores are operated in parallel.

Life Cycle Assessment of Medium Surge Arresters in the Context of Size‐Reduction Design

SummaryZinc oxide (ZnO) polycrystalline ceramics are the focal point of lightning arrester technology. These semiconductor materials are able to switch rapidly from high to low impedance while handling large amounts of electrical energy. Since the early 1970s, considerable efforts have been made to improve the specific energy absorption capacity and device reliability of such components. This document describes a case study carried out on the life cycle impacts of three different designs of electroceramics made of ZnO. Results show that the best design involves decreasing the diameter while maintaining the thickness of the compound. Of the production, transport, use, and end‐of‐life phases, the use phase is found to contribute by far the most to environmental impacts, with leakage currents in the 10−6 ampere range. The next‐largest impacts come in the transport and production stages. Sensitivity analysis shows that impacts associated with the production stage originate from ZnO production and are related to the by‐products (heavy metals) of zinc metallurgy.

Universal Tritium Transmitter

At the Savannah River Site and throughout the National Nuclear Security Agency (NNSA) tritium is measured using Ion or Kanne Chambers. Tritium flowing through an Ion Chamber emits beta particles generating current flow proportional to tritium radioactivity. Currents in the 1x 10-15 A to 1x 10-6 A are measured. The distance between the Ion Chamber and the electrometer in NNSA facilities can be over 100 feet. Currents greater than a few microamperes can be measured with a simple modification. Typical operating voltages of 500 to 1000 Volts and piping designs require that the Ion Chamber be connected to earth ground. This grounding combined with long cable lengths and low currents requires a very specialized preamplifier circuit. In addition, the electrometer must be able to supply “fail safe” alarm signals which are used to alert personnel of a tritium leak, trigger divert systems preventing tritium releases to the environment and monitor stack emissions as required by the United States federal Government and state governments. Ideally the electrometer would be “self monitoring”. Self monitoring would reduce the need for constant checks by maintenance personnel. For example at some DOE facilities monthly calibration and alarm checks must be performed to ensure operation. NNSA presently uses commercially available electrometers designed specifically for this critical application. The problems with these commercial units include: ground loops, high background currents, inflexibility and susceptibility to Electromagnetic Interference (EMI) which includes RF and Magnetic fields. Existing commercial electrometers lack the flexibility to accommodate different Ion Chamber designs required by the gas pressure, type of gas and range. Ideally the electrometer could be programmed for any expected gas, range and high voltage output. Commercially available units do not have “fail safe” self monitoring capability. Electronics used to measure extremely low current must have sufficient time to thermally equilibrate. Amplifiers, transistors, resistors all need time to stabilize before the electrometer circuit will measure accurately in the 10-15 and 10-14 ampere range. Existing electrometers give the user no indication when the unit has stabilized and is acceptable for low level measurements. Savannah River National Laboratory (SRNL) funded through the NNSA Plant Directed Research and Development (PDRD) program, has developed a truly Universal Tritium Transmitter (UTT) capable of solving many known problems with existing commercial electrometers. This UTT pushes the state-of-the-art in electrometer design and incorporates solutions to deficiencies found in commercial electrometers.

Production of large area low-energy electron beams by extraction from a multidipolar plasma (abstract)

The production of large area low-energy electron beams by extraction from a low-pressure plasma is investigated. In order to extract electron beams of given energy from a plasma, the plasma potential, as referred to wall potential, must be stationary and independent of the extraction potential. The macroscopic neutrality of the plasma therefore requires that reactor walls are metallic and that extraction to reactor wall area ratio is less than the square root of the electron to ion mass ratio. These specifications are fulfilled in the source presented in this study where the plasma is produced in a cylindrical chamber by seven elementary dipolar sources distributed over the end flange of a cylindrical chamber opposite to the extraction grid. The plasma is sustained at electron cyclotron resonance by microwaves at 2.45GHz in the chamber whose wall potential (extraction potential) can be varied from 0to−200V with respect to the ground potential. The electron beam extracted from the plasma through the grid then expands in a second chamber whose walls are set at the ground potential. The details of the experimental arrangement built on the above specifications are presented and the characteristics of argon plasmas measured by using cylindrical Langmuir probes as a function of the extraction voltage. In the same way, electron beam characteristics in the ground potential chamber are also measured using both planar and cylindrical Langmuir probes. In particular, variations in plasma and beam potentials are simultaneously determined as a function of extraction voltage. Current-voltage extraction characteristics are also reported, which show that electron beams in the ampere range can be extracted between 0 and −200V. The experimental results are in good agreement with the expected electron source behavior.

Ball Lightning–Aerosol Electrochemical Power Source or A Cloud of Batteries

Despite numerous attempts, an adequate theoretical and experimental simulation of ball lightning still remains incomplete. According to the model proposed here, the processes of electrochemical oxidation within separate aerosol particles are the basis for this phenomenon, and ball lightning is a cloud of composite nano or submicron particles, where each particle is a spontaneously formed nanobattery which is short-circuited by the surface discharge because it is of such a small size. As free discharge-shorted current loops, aerosol nanobatteries are exposed to a powerful mutual magnetic dipole–dipole attraction. The gaseous products and thermal energy produced by each nanobattery as a result of the intra-particle self-sustaining electrochemical reactions, cause a mutual repulsion of these particles over short distances and prevent their aggregation, while a collectivization of the current loops of separate particles, due to the electric arc overlapping between adjacent particles, weakens their mutual magnetic attraction over short distances. Discharge currents in the range of several amperes to several thousand amperes as well as the pre-explosive mega ampere currents, generated in the reduction–oxidation reactions and distributed between all the aerosol particles, explain both the magnetic attraction between the elements of the ball lightning substance and the impressive electromagnetic effects of ball lightning.

Effect of low-frequency electromagnetic casting on the castability, microstructure, and tensile properties of direct-chill cast Al-Zn-Mg-Cu alloy

Microstructure and grain boundary segregation of the direct-chill (DC) cast Al-Zn-Mg-Cu (7A60) alloy, with and without low-frequency electromagnetic field, were investigated. The surface quality, hot-tearing tendency, and tensile properties of the ingots manufactured by DC and low-frequency electromagnetic field casting (LFEC) were compared. The results show that LFEC significantly improves the surface quality and reduces the hot-tearing tendency of DC ingots. It is possible to generate a fine, uniform, and equiaxed microstructure with LFEC. Under optimum conditions, the average grain size varies from 30 µm near the surface to 45 µm at the center of the LFEC ingots. Decreasing electromagnetic frequency or increasing intensity significantly refines microstructure, suppresses grain boundary segregation, and increases as-cast fracture strength and elongation. In the range of frequency and ampere turns employed in the experiments, the optimum frequency is found to be 15 to 25 Hz and the number of ampere turns to be 18,000 to 20,000 At.

Microscopic analysis of chromium accumulation in the bronchi and lung of chromate workers.

It is known that chromium is an inhaled carcinogen and an important risk factor in the development of lung carcinoma. The authors used a microscopic X-ray fluorescence analyzer with transmitted X-ray mapping imaging (Horiba, Kyoto, Japan) to measure the accumulation of chromium in 10 resected lung tissue specimens and 90 biopsy specimens from chromate workers. The maximum chromium accumulation (mean +/- standard deviation) in 10 resected lung tissue specimens was 197 +/- 238 counts per second (cps)/mili ampere (mA) (range, 4-649 cps/mA). Chromium accumulation was scattered in six tissue specimens and diffuse in one specimen. Chromium accumulation in the proximal bronchi was less than in the bronchioles or subpleural regions of the lung. Chromium accumulation was detectable in 63 (70%) of 90 biopsy specimens, and the mean accumulation was 6.5 +/- 9.2 cps/mA (range, 0-46.5 cps/mA). Chromium detected in bronchial tissue specimens was deposited in the bronchial stroma but not in the epithelium. The maximum chromium accumulations in dysplasic (n = 3), squamous metaplastic (n = 10), and normal bronchial epithelia (n = 9) in chromate workers and in normal bronchial epithelia (n = 3) in non-chromate workers were 20.2 +/- 5.4, 18.3 +/- 12.2, 13.2 +/- 13.4, and 3.0 +/- 1.8 cps/mA, respectively. The amount of chromium accumulation significantly increased according to the progression of malignant change of the bronchial epithelium (P = 0.003). Previous studies found that lung carcinoma with chromate exposure exhibited a variety of genetic abnormalities. Considering genetic aberrations and chromium accumulation in these premalignant lesions is useful for elucidating the process of carcinogenesis in chromium-induced lung carcinoma.

Surface processing of sheet metal using metal ion beams

The hazardous waste generated by wet coating processes has led to considerable interest in dry coating processes, such as physical vapor deposition (PVD). A critical step in the PVD process is the cleaning of the substrate prior to coating deposition. The ion beam sputtering of substrate surfaces has been shown to be an excellent means of removing surface contaminants and oxide layers, substantially enhancing coating adhesion. In standard practice, sputtering is accomplished with a low energy beam of argon ions, because gas ion sources are readily available, argon is easy to ionize, and argon sputtering coefficients are fairly high. However, coating sheet steel at processing rates on the order of 5 m 2 s −1 requires beam currents of the order of several amperes. While the ion sources are readily available, the cost to vacuum pump the argon can become prohibitive. High current, pure beams of metal ions can be produced by vacuum arc technology. As vacuum arc sources do not require any carrier gas, the problem of gas pumping is eliminated. In addition, it should be possible to partially implant the surface during the sputter cleaning to further enhance the adhesion by addition of coating-compatible metal. The same equipment can also be used in place of gas ion sources for ion beam assisted deposition. As metal ions are incorporated into the coating, the species can be chosen to be compatible with the coating, e.g. chromium for chromium nitride deposition, or to provide additional properties, e.g. yttrium to stabilize zirconium oxide. A d.c. low voltage cathodic arc ion source has been developed, with ion beam currents in the ampere range even for very heavy metals, such as tantalum. The potential for this source for sputter cleaning and ion beam assisted deposition of sheet steel is discussed.

Evaluation of different cleaning techniques for oxygen-free high-conductivity copper

Oxygen-free high-conductivity copper is a candidate material for future electron/positron storage rings with beam currents in the range of ampere or more. The advantages being high electrical conductivity and good x-ray absorption. However, there are problems of fabrication and lack of extensive data on easy cleaning techniques for complicated shapes. We have over the last year gained considerable experience and understanding of the same. Techniques varying from conventional chemical cleaning, high-pressure hot-water jet cleaning, and vacuum bakeout, to novel methods such as CO2 snow cleaning, and wet bead blasting have been tried. The samples were evaluated for surface cleanliness by x-ray photoelectron spectroscopy. Data along with some analysis and interpretation are being presented.

Vacuum arc ion sources for particle accelerators and ion implantation

The vacuum arc is a generator of highly ionized metal plasma. This method of plasma production can be used to construct a high-current metal ion source. A succession of such metal-vapor vacuum arc ion sources has been developed at Berkeley. Beams from 50 of the solid metals of the periodic table have been produced with mean ion energy up to several hundred keV, and with pulsed beam currents in the ampere range. Typically the source is repetitively pulsed with a pulse length of 250 mu s and a duty cycle of the order of 1%. A DC embodiment from which a large-area titanium beam with steady-state ion current of 600 mA was produced has been tested. A 50-cm-diameter set of beam formation grids has been used to form a beam of area 1000 cm/sup 2/ at an energy of 100 keV and a pulsed beam current of approximately 10 A. The source can also be seen as a tool for the study of vacuum arc plasmas. Vacuum arc ion charge state distributions have been studied in this way. The general features and performance characteristics of the sources and their use for accelerator injection and ion implantation applications are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>