A systematic literature review on Virtual Reality and Augmented Reality in terms of privacy, authorization and data-leaks

In recent years, VR and AR has exploded into a multimillionaire market. As this emerging technology has spread to a variety of businesses and is rapidly increasing among users. It is critical to address potential privacy and security concerns that these technologies might pose. In this study, we discuss the current status of privacy and security in VR and AR. We analyse possible problems and risks. Besides, we will look in detail at a few of the major concerns issues and related security solutions for AR and VR. Additionally, as VR and AR authentication is the most thoroughly studied aspect of the problem, we concentrate on the research that has already been done in this area.Comment: 9 Pages, 4 figure

Modeling and Optimization of Ultrasonic Welding Process for Low Density Polymer: A Review

The purpose of this research is to determine the effect of various weld and machine parameters on ultrasonic weld strength. In this we are going to use thermosetting material named epoxy which is one of the low density polymers. By considering three main parameters that is amplitude, pressure and weld time we are going to conduct the experiment. After doing the welding, we will check the tensile strength of the welded pieces by using UTM. (Universal testing machine).Further with the help of MINITAB software we will optimize the number of experiments

Evaluation of persistent-mode operation in a superconducting MgB2 coil in solid nitrogen

We report the fabrication of a magnesium diboride (MgB2) coil and evaluate its persistent-mode operation in a system cooled by a cryocooler with solid nitrogen (SN2) as a cooling medium. The main purpose of SN2 was to increase enthalpy of the cold mass. For this work, an in situ processed carbon-doped MgB2 wire was used. The coil was wound on a stainless steel former in a single layer (22 turns), with an inner diameter of 109 mm and height of 20 mm without any insulation. The two ends of the coil were then joined to make a persistent-current switch to obtain the persistent-current mode. After a heat treatment, the whole coil was installed in the SN2 chamber. During operation, the resultant total circuit resistance was estimated to be \u3c7.4x10−14 Ω at 19.5 K±1.5 K, which meets the technical requirement for magnetic resonance imaging application

Design and fabrication of solid nitrogen cooled MgB2 based persistent magnet for MRI application

Physicians and surgeons rely critically on magnetic resonance imaging (MRI) scans to diagnose and treat critical injuries and medical conditions. In an MRI system, high, stable (\u3c0.1 ppm h-1), and uniform (≤10 ppm in 50 cm diameter of spherical volume) magnetic fields are required for obtaining high-resolution images of the human body. The unique possibilities for the operation of superconducting magnets (i.e., persistent-mode) make them ideal for MRI application. Thus, in the majority of commercially available MRI systems, superconducting persistent magnets based on niobium titanium (NbTi) have been used. These magnets, which are cooled in an expensive liquid helium (LHe) bath at 4.2 K, cannot currently be avoided. Thus, the high operation costs of MRI systems obstruct their extensive use in developing and underdeveloped countries

Magnesium diboride(Mgb2) wires for applications

Field and temperature dependence of the critical current density, Jc, were measured for both un-doped and carbon doped MgB2/Nb/Monel wires manufactured by Hyper Tech Research, Inc. In particular, carbon incorporation into the MgB2 structure using malic acid additive and a chemical solution method can be advantageous because of the highly uniform mixing between the carbon and boron powders. At 4.2 K and 10 T, Jc was estimated to be 25,000 - 25,300 Acm-2 for the wire sintered at 600°C for 4 hours. The irreversibility field, Birr, of the malic acid doped wire was approximately 21.0 - 21.8 T, as obtained from a linear extrapolation of the J-B characteristic. Interestingly enough, the Jc of the malic acid doped sample exceeds 105 Acm-2 at 6 T and 4.2 K, which is comparable to that of commercial Nb-Ti wires

Surgical Reconstruction of Carapace Fracture in an Indian Black Turtle

Shell injuries are a common presentation in wild and captive turtles. There are many methods of fracture fixation, which based on the characteristics of the fracture. The present paper discussed about the surgical reconstruction of carapace fracture in an indian black turtle by using orthopedic wire and dental luting cement. An Indian black turtle/Indian pond terrapin (Melanochelys trijuga) weighing 1.1 kg was presented with a displaced fracture of the right side of the carapace involving IM, IIM, IIIM & IVM marginal, IP & IIP pleural and IVe vertebral scutes with a depressed fracture involving II pleural scute. The coelomic membrane was exposed but intact. The wound was noticed at the fractured site and was contaminated. A dorso-ventral radiograph revealed fractured and displaced carapace over the right forelimb with the intact spinal card. Under Ketamine sedation the fractured fragments were immobilized by 26G stainless steel orthopedic wire, inter fragmental space was sealed using dental luting cement (Lute glass) to avoid infiltration of water into wound when the turtle was left in the water. Enrofloxacin was administered intramuscularly at a dose rate 5 mg/kg every 48 hours interval of 6 days. Meloxicam was administered intramuscularly at adose rate 0.2 mg/kg body weight every 24 hours interval for 3 days post-operatively. After complete recovery the turtle was released in its natural habituated place

Solid cryogen: a cooling system for future MgB2 MRI magnet

An efficient cooling system and the superconducting magnet are essential components of magnetic resonance imaging (MRI) technology. Herein, we report a solid nitrogen (SN2) cooling system as a valuable cryogenic feature, which is targeted for easy usability and stable operation under unreliable power source conditions, in conjunction with a magnesium diboride (MgB 2) superconducting magnet. The rationally designed MgB 2/SN2 cooling system was first considered by conducting a finite element analysis simulation, and then a demonstrator coil was empirically tested under the same conditions. In the SN2 cooling system design, a wide temperature distribution on the SN2 chamber was observed due to the low thermal conductivity of the stainless steel components. To overcome this temperature distribution, a copper flange was introduced to enhance the temperature uniformity of the SN2 chamber. In the coil testing, an operating current as high as 200 A was applied at 28 K (below the critical current) without any operating or thermal issues. This work was performed to further the development of SN2 cooled MgB 2 superconducting coils for MRI applications

Niobium-titanium (Nb-Ti) superconducting joints for persistent-mode operation

Superconducting joints are essential for persistent-mode operation in a superconducting magnet system to produce an ultra-stable magnetic field. Herein, we report rationally designed niobium-titanium (Nb-Ti) superconducting joints and their evaluation results in detail. For practical applications, superconducting joints were fabricated by using a solder matrix replacement method with two types of lead-bismuth (Pb-Bi) solder, including Pb42Bi58 as a new composition. All the joints attained a critical current of \u3e200 A below 1.43 T at 4.2 K. Our optimized superconducting joining method was tested in a closed-loop coil, obtaining a total circuit resistance of 3.25 x 10-14 Ω at 4.2 K in self-field. Finally, persistent-mode operation was demonstrated in an Nb-Ti solenoid coil with a persistent-current switch. This work will pave the way to developing high-performance Nb-Ti superconducting joints for practical applications

Improvement in the transport critical current density and microstructure of isotopic Mg\u3csup\u3e11\u3c/sup\u3eB2 monofilament wires by optimizing the sintering temperature

Superconducting wires are widely used in fabricating magnetic coils in fusion reactors. In consideration of the stability of 11B against neutron irradiation and lower induced radio-activation properties, MgB2 superconductor with 11B serving as boron source is an alternative candidate to be used in fusion reactor with severe irradiation environment. In present work, a batch of monofilament isotopic Mg11B2 wires with amorphous 11B powder as precursor were fabricated using powder-in-tube (PIT) process at different sintering temperature, and the evolution of their microstructure and corresponding superconducting properties was systemically investigated. Accordingly, the best transport critical current density (Jc) = 2 x 104 A/cm2 was obtained at 4.2 K and 5 T, which is even comparable to multi-filament Mg11B2 isotope wires reported in other work. Surprisingly, transport Jc vanished in our wire which was heat-treated at excessively high temperature (800 °C). Combined with microstructure observation, it was found that lots of big interconnected microcracks and voids that can isolate the MgB2 grains formed in this whole sample, resulting in significant deterioration in inter-grain connectivity. The results can be a constructive guide in fabricating Mg11B2 wires to be used as magnet coils in fusion reactor systems such as ITER-type tokamak magnet

A new approach to a superconducting joining process for carbon-doped MgB2 conductor

We report a new approach to a superconducting joining process for unreacted in situ carbon (C)-doped magnesium diboride (MgB2) wires. To operate a magnetic resonance imaging (MRI) magnet in the persistent mode, the superconducting joints between two conductors are as critical as the other key components. In addition, a stable and reliable joining process enables the superconducting magnet to operate without an external power supply. However, joint results using unreacted in situ C-doped MgB2 wires, which are used for high-field operation, have been limited, and only very poor performance has been obtained. By controlling the pressure inside a joint part, in this study, we successfully obtained current carrying retention in the joint of up to 72% compared to wire without a joint. The closed-circuit resistance of our closed-loop coil was less than 1.8 x 10−13 Ω at 16.7 ± 4.7 K, as measured by the field-decay measurement method. These results indicate that MgB2 has a promising future in MRI application