Development and Test of a Portable ECG Device with Dry Capacitive Electrodes and Driven Right Leg Circuit

The use of wearable sensors for health monitoring is rapidly growing. Over the past decade, wearable technology has gained much attention from the tech industry for commercial reasons and the interest of researchers and clinicians for reasons related to its potential benefit on patients’ health. Wearable devices use advanced and specialized sensors able to monitor not only activity parameters, such as heart rate or step count, but also physiological parameters, such as heart electrical activity or blood pressure. Electrocardiogram (ECG) monitoring is becoming one of the most attractive health-related features of modern smartwatches, and, because cardiovascular disease (CVD) is one of the leading causes of death globally, the use of a smartwatch to monitor patients could greatly impact the disease outcomes on health care systems. Commercial wearable devices are able to record just single-lead ECG using a couple of metallic contact dry electrodes. This kind of measurement can be used only for arrhythmia diagnosis. For the diagnosis of other cardiac disorders, additional ECG leads are required. In this study, we characterized an electronic interface to be used with multiple contactless capacitive electrodes in order to develop a wearable ECG device able to perform several lead measurements. We verified the ability of the electronic interface to amplify differential biopotentials and to reject common-mode signals produced by electromagnetic interference (EMI). We developed a portable device based on the studied electronic interface that represents a prototype system for further developments. We evaluated the performances of the developed device. The signal-to-noise ratio of the output signal is favorable, and all the features needed for a clinical evaluation (P waves, QRS complexes and T waves) are clearly readable.

Development of the Vacuum Arc Chute for a 110 kV Single-Break Vacuum Circuit Breaker

Requirements for high-voltage vacuum circuit breakers for networks with a grounded neutral, which are stemming from the prospects of using vacuum circuit breakers in networks with the solidly grounded neutral are formulated. The arch chute design for a 110 kV single-break vacuum circuit breaker that takes into account the occurrence of repeated breakdowns is developed. The shielding system equalizes the voltage over the chute casing, decreases the electric field intensity at the “triple point”, protects the casing dielectric from becoming dusted with metallic contact parts erosion products, prevents the occurrence of cascade breakdown between the contact parts and central shield, and eliminates a possible decrease of the chute electric strength as it gradually works out its switching life. It is shown that the chute design includes measures to prevent the possibility of repeated breakdowns during disconnection up to class С1 according to GOST 52565-2006. It has been proven that for vacuum arc chutes for class С2 (for switching a capacitive load) it is necessary to develop a chute with two breaks between the contact parts or to connect two vacuum chutes in series. The shielding system adopted in the chute rules out the possibility of ceramic casing to become metallized, which decreases the chute electric strength as it gradually works out its switching life, and the vacuum arc transfer to beyond the inter-contact gap boundaries onto the central shield, the burnout of which results in that the vacuum arc chute loses its tightness and fully loses its functional properties.

Purifying crude petroleum by using porous ceramic balls

Background: Background: In this study ceramic crude petroleum filter was prepared from Iraqi White Kaolin with ratio (70%) and Alumina (Al2O3) with ratio (30%), with natural additives Palm Frond with ratios (5,10,15,25,35 and 45)% in different partical size to produce pores, formed by dry pressing then fairing at 1100(˚C). The filters are harmless and environmentally friendly materials. Some assessments were carried out, such as (apparent porosity ratio, water absorption ratio, and apparent density). From the test results obtained the apparent porosity was 60.7% , water absorption was 89.3% and an apparent density of 0.68% with a 45% ratio of fine (P.F). Methods: Size and distribution of pores were characterized by using Scanning Electron Microscope (SEM). The crude petroleum treated with filters evaluated by tests such as (API Gravity, Sulfur Content, Asphaltenes Content, and Metallic Content). Results: The result of API Gravity before immersion crude petroleum filter balls was 24.70 and after immersion crude petroleum filter balls for 7 days for 30 % (P.F) increase to 31.0 and reach to 32.5 after immersion for 14 days. Sulfur Content before immersion crude petroleum filter balls was 3.76 and after immersion crude petroleum filter balls for 7 days for 30 % (P.F) decrease down to 3.1 and reach to 2.6 after immersion for 14 days. Conclusion: So Asphaltenes content before immersion crude petroleum filter balls was 6.68 and after immersion crude petroleum filter balls for 7 days 30 % (P.F) decreased down to 2 and reach to 1.6 after immersion for 14 days, metallic contact such as Vanadium and Nickel before immersion crude petroleum filter balls respectively was 86 ppm, 32 ppm while after immersion crude petroleum filter balls for 7 days they become 53.26 ppm and 15.35 ppm and for 14 days they reached to 47.52 ppm and 11.43 ppm respectively.

Geometry Optimization of Top Metallic Contacts in a Solar Cell Using the Constructal Design Method

Sunlight is a natural resource that can be harnessed by the photovoltaic conversion of sunlight into electricity-utilizing solar cells. The production of most common solar cells consists of a homojunction of a p-type and n-type silicon. The p—n junction is realized by the diffusion of impurities through one surface of the wafer. Silicon wafers have a typical dimension of 156 × 156 mm2 and a thickness of 0.15–0.2 mm. Groups of 50–100 solar cells are electrically connected and encapsulated to form a module. The required area for interconnection does not contribute to power generation, and the performance of larger area devices usually suffers from higher resistive losses. In the present work, a theoretical model of the geometric arrangement of the top contact metallic electrodes branched network in a photovoltaic cell is developed. The network structure of the electrodes is obtained from applying the constructal design methodology by the minimization of the overall resistance. As a result, the optimal lengths and geometrical relationships of an electrode branching network with a branching angle are determined. A geometric distribution of the electrode network on the solar cell analyzed by the total resistance of every level of branching is defined. The top metallic contact network presents a tree-shaped geometric arrangement with the main objective of covering a generation area for an enhanced collection of the generated electrical current. The theoretical results obtained are expressed as the total voltage of the arrangement and the lengths of the branched electrode network.

A Novel Metal Nanoparticles-Graphene Nanodisks-Quantum Dots Hybrid-System-Based Spaser

Active nanoplasmonics have recently led to the emergence of many promising applications. One of them is the spaser (surface plasmons amplification by stimulated emission of radiation) that has been shown to generate coherent and intense fields of selected surface plasmon modes that are strongly localized in the nanoscale. We propose a novel nanospaser composed of a metal nanoparticles-graphene nanodisks hybrid plasmonic system as its resonator and a quantum dots cascade stack as its gain medium. We derive the plasmonic fields induced by pulsed excitation through the use of the effective medium theory. Based on the density matrix approach and by solving the Lindblad quantum master equation, we analyze the ultrafast dynamics of the spaser associated with coherent amplified plasmonic fields. The intensity of the plasmonic field is significantly affected by the width of the metallic contact and the time duration of the laser pulse used to launch the surface plasmons. The proposed nanospaser shows an extremely low spasing threshold and operates in the mid-infrared region that has received much attention due to its wide biomedical, chemical and telecommunication applications.

Vertical integration of microchips by magnetic assembly and edge wire bonding

The out-of-plane integration of microfabricated planar microchips into functional three-dimensional (3D) devices is a challenge in various emerging MEMS applications such as advanced biosensors and flow sensors. However, no conventional approach currently provides a versatile solution to vertically assemble sensitive or fragile microchips into a separate receiving substrate and to create electrical connections. In this study, we present a method to realize vertical magnetic-field-assisted assembly of discrete silicon microchips into a target receiving substrate and subsequent electrical contacting of the microchips by edge wire bonding, to create interconnections between the receiving substrate and the vertically oriented microchips. Vertical assembly is achieved by combining carefully designed microchip geometries for shape matching and striped patterns of the ferromagnetic material (nickel) on the backside of the microchips, enabling controlled vertical lifting directionality independently of the microchip’s aspect ratio. To form electrical connections between the receiving substrate and a vertically assembled microchip, featuring standard metallic contact electrodes only on its frontside, an edge wire bonding process was developed to realize ball bonds on the top sidewall of the vertically placed microchip. The top sidewall features silicon trenches in correspondence to the frontside electrodes, which induce deformation of the free air balls and result in both mechanical ball bond fixation and around-the-edge metallic connections. The edge wire bonds are realized at room temperature and show minimal contact resistance (<0.2 Ω) and excellent mechanical robustness (>168 mN in pull tests). In our approach, the microchips and the receiving substrate are independently manufactured using standard silicon micromachining processes and materials, with a subsequent heterogeneous integration of the components. Thus, this integration technology potentially enables emerging MEMS applications that require 3D out-of-plane assembly of microchips.

Investigation of different tribological systems during full forward impact extrusion of aluminum alloy EN AW 6082

Purpose The modification of the tribological system is an essential aspect of the implementation of resource-saving processes in cold forming. As a result, the focus of this contribution is the influence of the tribological system on the full forward impact extrusion of aluminum alloy EN AW 6082 (T6) with regard to reduction of friction and wear. Design/methodology/approach The investigations included a variation of lubricant and die treatment. Friction, wear and the mean arithmetic height Sa were used as evaluation criteria. The aim was to find a suitable die surface treatment and a suitable lubricant on the basis of the evaluation criteria. Findings The experiments indicated that each of the selected tribological systems prevents physical metallic contact between tool and workpiece and thus prevents the formation of wear. Nevertheless, differences were found in the areas of smoothing of workpiece surfaces and adhesive strength of lubricants. Originality/value As general cause effect relationships between die coating and lubricant are not known in the field of bulk metal forming of aluminum, fundamental investigations are described below. The investigations focus on the influence of the material and the tribological system on friction as well as wear. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0316