A Novel Dual-Band Implantable Antenna for Pancreas Telemetry Sensor Applications

In this study, a novel implantable dual-band planar inverted F-antenna (PIFA) is proposed and designed for wireless biotelemetry. The developed antenna is intended to operate on the surface of the pancreas within the Medical Device Radiocommunications Service (MedRadio 401–406 MHz) and the industrial scientific and medical band (ISM, 2.4–2.5 GHz). The design analysis was carried out in two steps, initially inside a canonical model representing the pancreas, based on a finite element method (FEM) numerical solver. The proposed antenna was further simulated inside the human body taking into account the corresponding dimensions of the tissues and the electrical properties at the frequencies of interest using a finite-difference time-domain (FDTD) numerical solver. Resonance, radiation performance, electrical field attenuation, total radiated power, and specific absorption rate (SAR), which determines the safety of the patient and the maximum permissible input power and other electromagnetic parameters, are presented and evaluated.

Observational scalings testing modified gravity

We consider different observational effects to test a modified gravity approach involving the cosmological constant in the common description of dark matter and dark energy.We obtain upper limits for the cosmological constant by studying the scaling relations for 12 nearby galaxy clusters, the radiated power from gravitational waves and the Tully-Fisher relation for super spiral galaxies. Our estimations reveal that, for all these cases, the upper limits for Λ are consistent with its actual value predicted by cosmological observations.

Performance Improvement of Substrate Integrated Cavity Fed Dipole Array Antenna Using ENZ Metamaterial for 5G Applications

This paper exhibits a high-gain, low-profile dipole antenna array (DAA) for 5G applications. The dipole element has a semi-triangular shape to realize a simple input impedance regime. To reduce the overall antenna size, a substrate integrated cavity (SIC) is adopted as a power splitter feeding network. The transition between the SIC and the antenna element is achieved by a grounded coplanar waveguide (GCPW) to increase the degree of freedom of impedance matching. Epsilon-near-zero (ENZ) metamaterial technique is exploited for gain enhancement. The ENZ metamaterial unit cells of meander shape are placed in front of each dipole perpendicularly to guide the radiated power into the broadside direction. The prospective antenna has an overall size of 2.58 λg3 and operates from 28.5 GHz up to 30.5 GHz. The gain is improved by 5 dB compared to that of the antenna without ENZ unit cells, reaching 11 dBi at the center frequency of 29.5 GHz. Measured and simulated results show a reasonable agreement.

High–confinement radiative L–modes in ASDEX Upgrade

Experiments have been performed in the ASDEX Upgrade tokamak where plasmas are kept just below the H--mode threshold using feedback on the radiated power via seeded impurity. The resulting high--power L--modes show high confinement properties and no ELM activity due to the reduced pedestal height. The physics of these high--confinement L--modes is explored by means of integrated modeling to clarify the origin of the improved confinement.

Low-Complexity Receiver for Massive MIMO-GFDM Communications

OFDM has two disadvantages. The first is high peak-to-average power ratio (PAPR), and the second is high out-of-band (OOB) radiated power. In the future communication applications, the diversified scenarios such as Internet of Things, inter-machine communication and telemedicine make the fourth-generation mobile communication no longer applicable. The generalized frequency division multiplexing (GFDM) has a pulse-shaping filter, which has less out-of-band radiated power and peak-to-average power ratio and fewer cyclic prefixes (CP) than OFDM. In order to meet high- data-transmission rate, it is an inevitable trend to install massive multi-input multi-output (massive MIMO) antennas. As the number of antennas increases, so does its complexity. This paper employs time reversal (TR) technology to reduce the computational complexity. Although the number of base station (BS) antennas has increased to eliminate interference, there is still residual interference. In order to eliminate the interference one step further, we deploy a zero forcing equalization (ZF equalization) after the time reversal combination.

A New Stripline-Based Atmospheric Pressure Microwave Plasma Sheet Source Designed for Surface Modification of Materials

A new type of microwave plasma source is presented in which plasma at atmospheric pressure is generated inside a quartz rectangular flat box placed in a stripline supplied by a 2.45 GHz coaxial line. The plasma has a sheet shape and is designed for surface modification. Electric field and power flux distributions, tuning characteristics, and power characteristics (ratios of radiated, absorbed, and entering power) are numerically studied for three configurations: open, semi-closed, and closed. The calculations show that near-zero radiation reduction is possible only for the closed configuration, while the ratio of radiated power to entering power is always greater than 30% for the other configurations. The moving plunger is not sufficient for the ratio of reflected to incident power to fall below 20% for both the closed and open configurations. This is possible for the semi-closed configuration, but then the radiated power is the highest. The experiment shows that for the same entering power, the plasma volume is largest for the closed configuration and smallest for the open configuration, which we attribute to the difference in radiated power. The plasma generated using the closed stripline configuration has a larger volume than plasma generated using the rectangular waveguide.

Plasma-wall self-organization in magnetic fusion

This paper introduces the concept of plasma-wall self-organization (PWSO) in magnetic fusion. The basic idea is the existence of a time delay in the feedback loop relating radiation and impurity production on divertor plates. Both a zero and a onedimensional description of PWSO are provided. They lead to an iterative equation whose equilibrium fixed point is unstable above some threshold. This threshold corresponds to a radiative density limit, which can be reached for a ratio of total radiated power to total input power as low as 1/2. When detachment develops and physical sputtering dominates, this limit is progressively pushed to very high values if the radiation of non-plate impurities stays low. Therefore, PWSO comes with two basins for this organization: the usual one with a density limit, and a new one with density freedom, in particular for machines using high-Z materials. Two basins of attraction of PWSO are shown to exist for the tokamak during start-up, with a high density one leading to this freedom. This basin might be reached by a proper tailoring of ECRH assisted ohmic start-up in present middle-size tokamaks, mimicking present stellarator start-up. In view of the impressive tokamak DEMO wall load challenge, it is worth considering and checking this possibility, which comes with that of more margins for ITER and of smaller reactors.

Investigating the physics of disruptions with real-time tomography at JET

As JET is developing and testing operational scenarios for higher fusion performance, an increase in pulse disruptivity is being observed. On a deeper analysis, we find that several radiative phenomena play an active role in determining the outcome of the pulse. The analysis is enabled by the use of real-time tomography based on the bolometer diagnostic. Even though plasma tomography is an inverse problem, we use machine learning to train a forward model that provides the radiation profile directly, based on a single matrix multiplication step. This model is used to investigate radiative phenomena including sawtooth crashes, ELMs and MARFE, and their relationship to the radiated power in different regions of interest. In particular, we use real-time tomography to monitor the core region, and to throw an alarm whenever core radiation exceeds a certain threshold. Our results suggest that this measure alone can anticipate a significant fraction of disruptions in the JET baseline scenario.

Synthesis method of circulant polynomial encoding matrices for the implementation of code-division multiplexing

The method of the synthesis of circulant polynomial matrices for the implementation of the operation of code combining of channels on the transmitting side of the communication system has been developed. The structure of these matrices is the basis for reducing the complexity of encoder schemes and, consequently, the radiated power of radio transmitters of subscriber devices. The research results can be applied in communication systems with multiple access, with a wide coverage area, high quality of data transmission, high noise immunity, stability of communication channels from interception and eavesdropping.