The introduction of lung navigation systems in the clinical practice has enabled a transbronchial minimally invasive access to flexible microwave ablation catheters for the treatment of lung cancer lesions. These complex procedures are currently performed under Cone-Beam CT and require lung navigation system and bronchoscope. On bench lung models integrating tumor-mimicking targets for usability assessment are in demand due to the lack of representative in vivo models. In this paper, three tumor models made of minced bovine muscle, bovine tripe and ovine heart were integrated inside inflated ovine lungs and assessed in terms of radiopacity, required piercing force and dielectric properties. The impact of iodine to enhance radiopacity in the other desired model characteristics is also evaluated.
Evaluation of myocardial function is critical in severe inflammations as myocarditis, COVID-19 and sepsis, since it can lead to organ failure and death. Point-of-care detection of myocardial injury may improve the treatment of these critically ill patients. The study aimed to develop point of care technology for assessing the systolic and diastolic cardiac functions in animal model of systemic inflammation. Ultrasound and ventricular pressure were continuously recorded in Langendorff perfused isolated adult rat hearts. A computer controlled system controlled the ventricle loading conditions. The preload of both ventricles swung in a sinusoidal manner between target values of 2 and 22 mmHg. Collagenase (MMP8) was added to the Krebs-Henseleit solution following baseline recordings, to emulate the release of MMPs from activated leukocytes and macrophages. Collagenase perfusion led to gradual decline in peak systolic pressure and decrease in the end-diastolic volume (EDV), that were associated with concentric myocardial wall thickening. Extracellular matrix degradation by collagenases caused sever diastolic dysfunction with overt shift of the end-diastolic volume toward lower volumes, without significant changes in the epicardial diameter. Early detection of these signs may assist in assessing the severity of the myocardial injury and prompt the adequate treatment.
High precision indoor position estimation enables new opportunities for a variety of commercial, industrial and consumer applications. In this paper, we consider a phase-based method to calculate range from noisy measurements of a Frequency Comb in a multi-fading environment. It can be used to determine the range between devices for the next-generation High Accuracy Distance Measurement (HADM) protocol. We have conducted a quantitative analysis of various estimation approaches, considering both Monte-Carlo simulations of synthetic data in a variety of ranges. Moreover, we have proposed evaluation schemes for situations in which only a subset of data is available and some information may be missing, which extends existing approaches.
Cyber-Infrastructure (CI) is a critical element in achieving novel scientific discoveries and helping the research and development of new technologies. The next generation of research supporting CI should provide dynamic end-to-end platforms with guaranteed resource allocation and allow users to easily deploy the cyber-system elements and adapt them towards their current and future requirements. In this paper we consider a programmable cyber architecture which can implement this next generation of CI and discuss how the user requirements are met. This is based on a formal, comprehensive model for service abstraction and service construction – a framework and a generic virtualization model that offers a simplified common treatment of CI resources across all classes and services, in a scalable and secure architecture.
The increasing interest for high frequencies solicits the use of phaseless near-field-far-field (NF-FF) transformations for antenna characterization. The aim of this paper is to present a numerical validation of a phaseless NF-FF transformation with plane-polar scanning.A reduction of about 75% of the required NF samples as compared to standard λ/4 sampling is obtained by adopting an oblate spheroid to model the antenna under test (AUT) and by exploiting the non-redundant sampling representations of electromagnetic fields. An effective and proper representation of the unknowns, also taking advantage of the available information on the AUT, allows one to improve reliability and stability of the inversion process.Numerical results are presented.
This work proposes an Adaptive Fuzzy Prediction (AFP) method for the attenuation time series in Commercial Microwave links (CMLs). Time-series forecasting models regularly rely on the assumption that the entire data set follows the same Data Generating Process (DGP). However, the signals in wireless microwave links are severely affected by the varying weather conditions in the channel. Consequently, the attenuation time series might change its characteristics significantly at different periods. We suggest an adaptive framework to better employ the training data by grouping sequences with related temporal patterns to consider the non-stationary nature of the signals. The focus in this work is two-folded. The first is to explore the integration of static data of the CMLs as exogenous variables for the attenuation time series models to adopt diverse link characteristics. This extension allows to include various attenuation datasets obtained from additional CMLs in the training process and dramatically increasing available training data. The second is to develop an adaptive framework for short-term attenuation forecasting by employing an unsupervised fuzzy clustering procedure and supervised learning models. We empirically analyzed our framework for model and data-driven approaches with Recurrent Neural Network (RNN) and Autoregressive Integrated Moving Average (ARIMA) variations. We evaluate the proposed extensions on real-world measurements collected from 4G backhaul networks, considering dataset availability and the accuracy for 60 seconds prediction. We show that our framework can significantly improve conventional models’ accuracy and that incorporating data from various CMLs is essential to the AFP framework. The proposed methods have been shown to enhance the forecasting model’s performance by 30 − 40%, depending on the specific model and the data availability.
In this study, a metamaterial-based LTCC compressed Luneburg lens was designed, manufactured and measured. The lens was designed at 60 GHz to utilize the unlicensed mm-wave spectrum available for short-range high-capacity wireless communication networks. The transformation optics method was applied to ensure the compression of the Luneburg lens antenna and thus maintain a low-profile structure. The two different types of unit cells for low and high permittivity regions were considered. The parametric study of the effect of compression on lens performance was presented. The antenna is implemented with a standard high-permittivity LTCC process, and details of the manufacturing process for the metamaterial lens are discussed. The low-profile lens is thinner than 2 mm and measures 19 mm in diameter. A size reduction of 63.6% in comparison with a spherical lens was achieved. The near-field to far-field mm-wave measurement technique is presented, and the measurement results show a peak antenna gain of 16 dBi at 60 GHz and a beam-scanning capacity with 1 dB scan loss within a 50° field of view.
a new and practical perspective on the management of Parkinson's disease (PD) is introduced due to the progress in the field of medical imaging techniques in the charting of the mid-brain activities of the PD patients. A new cost-effective design of comfortably weighed personal helmet (microwave head-band type) sensor is the timely equipment to evaluate Parkinson Disease patients at home to maintain good physician-patient safety during pandemic worldwide lockdown. These microwave helmet sensor devices function as handy "stethoscopes" designed for the PD medical staffs and patients. They are also very practical tool for the PD patients to check their physical conditions and alert them to perform suitable body exercise to reduce their PD symptoms [1].
This work presents a neural network (NN) implementation of a digital self-interference cancellation (SIC) filter and a digital predistortion (DPD) linearizer in a quadrature balanced full duplex (FD) transceiver front-end. A quantitative description of the NNs design and functionality is laid out. The proposed algorithms were evaluated in measurements using a discrete-component quadrature balanced RF front-end and a 20 MHz 802.11ac WiFi signal with 10 dB peak-to-average power ratio (PAPR) around the center frequency of 2.4 GHz. At 13 dBm average transmit (TX) power, the NN-DPD corrects TX error vector magnitude (EVM) by 13 dB to the value of -41.5 dB. Total TX-RX isolation of 50 dB is demonstrated in the RF domain, out of which 20 dB is contributed by the passive TX-RX isolation and 30 dB by active TX leakage suppression using the NN SIC filter.
A Near-Field/Far-Field technique employing a prolate spheroidal modelling of the source is presented.The approach is devised for oblong antennas which can be accommodated within a prolate spheroid and can be applied to non-directive antennas or directive antennas on one far-field cut only. The tangential components of the electric field over the spheroidal surface are expanded by Prolate Spheroidal Wave Functions (PSWFs) so that the unknowns of the problem amount to be the representation coefficients. Such coefficients are related to the tangential components of the field measured on a cylindrical surface and are determined, in a regularized way, by a Singular Value Decomposition approach.The PSWFs are calculated according to the method devised by Adelman, Gumerov and Duraiswami.Numerical results presented.
In this work a novel concept to realize wideband matches at high frequencies with standard manufacturing processes without the need for additional fabrication steps or materials is presented. This is achieved by incorporating the high dielectric losses in substrates based on epoxy and glass fibers. The benefits of this approach for real applications are demonstrated by the design and fabrication of an illustrative load. This wideband match was then validated with an absolute reflection coefficient of around −20dB between 50 and 110GHz. Parameters critical for performance are presented and their impact is examined in theory and verified by full wave simulations and measurements.
In this paper a Y-band THz radiating CMOS source in the is presented. The source is based on a differential buffer- less Colpitts D-band VCO, which is tuned by controlling its gate- source capacitance through its transistor drain-gate voltage. The transistor drains are directly coupled to an on-chip loop antenna that chokes the fundamental signal while efficiently radiating the 3rd harmonic generated by the VCO transistor non-linearity. The source is locked using an external D-band source that radiates the CMOS chip and injection locks the source through its fundamental oscillation. The source can be tuned in a wide frequency range of 405 to 421 GHz with peak total output power of -15dBm (DC to THz radiated power efficiency of 0.1%), EIRP of -6 dBm and DC to EIRP power efficiency of 1.1%. This concept enables simple and cost-effective locked CMOS THz source arrays.
The current science-based approach to ensuring public safety from RF-EMF base stations is described, and a potential misframing of the debate as a purely scientific issue, which in turn led to inappropriate risk communication exercises, is pointed to. Plausibly, this polarised and charged the situation by disenfranchising other potentially legitimate siting concerns. While the primary health recommendation remains unchanged, namely, to follow the guidelines set by the science-based ICNIRP and IEEE expert groups, and to limit the ICNIRP 2020 and IEEE 95.12019 power density exposure level for general-public: between 400 – 2000 MHz fMHz/200 (W/m2) and 10 (W/m2) above 2000 MHz, other legitimate concerns should not be disregarded.
This work analyzes a modified linear smart antenna array that uses the Particle Swarm Optimization (PSO) method to maximize the main lobe while minimizes the sidelobes. The antenna array is composed of four commercial seven-element Yagi-Uda antennas and is said to be modified in the sense that the two extreme antennas are tilted sideways at 70° while the other two remain parallel to each other. The electrical feeds of the antennas, phase, and amplitude, are the only parameters to be optimized. An electronically smart antenna was designed, simulated, built, and tested. Simulated and measured radiation pattern results are here reported.
We report the manufacturing and integration of lab grown microcrystaline diamond in the wafer and package of advanced silicon integrated circuits and compound semiconductor processes. Diamond which has a thermal conductivity of 1500-2200 W/(m*K), four times higher than copper and fifteen time higher than silicon, significantly reduces the thermal spreading resistance and the junction / core temperature. We present perfomance stress test results performed on a state of the art processor with embedded diamond heat spreader showing a marked increase in processor speed and reduced core temperature when compared to a the same processor in a standard package. A marked reduction in cores temperature spread is also displayed by the diamond embedded processor. Results for power device performance improvement are also described.
An efficient method is presented to simulate a 3D antenna connected to a finite ground plane itself lying on a layered medium. The spectral interactions between equivalent currents of the antenna and the finite ground plane are accelerated thanks to an asymptotic extraction of the integrated spectrum. The term accounting for the asymptotic part is obtained in free-space. Besides, efficient techniques for finite ground planes of canonical shapes cannot be considered in this case because the connection between the ground plane and the antenna is established with a fine mesh region which breaks the symmetries of the finite ground plane equivalent currents. Here a method to remedy this issue and which efficiently simulates defected rectangular ground planes is presented. The method is based on Toeplitz matrices and the defect is taken into account by exploiting a memory-efficient direct method.
Rain fields’ simulation is an important tool for several research fields and applications. However, most simulations are based on a naive model that cannot capture complex spatial distribution. In this work, we present RainGAN, a generative model that enables a generation of a realistic, complex rain field that is conditioned on user parameters such as max peak, number of peaks, etc. In addition, we construct a dataset of typical rain fields that are based on radar measurement and have been utilized in the training process. We conducted several experiments and demonstrate the generator quality using both numerical and visual results.
The article proposes metamaterials application for the electromagnetic shielding of an antenna that may be used in a vehicle’s Bluetooth communication system. The electromagnetic shielding process consists of reducing the dispersion of electromagnetic waves that affect a device of interest. The three main parameters of interest in the electromagnetic shielding process are reflection, absorption, and multiple reflections. The results of the application of metamaterials in the microstrip antenna structure are promising in these parameters. The S11 parameter decreased from -21.7 dB (2.4 GHz) to -30.6 dB with metamaterial. The RCS (cross-section radar) was optimized with the application of metamaterials, for theta and phi = 0° the RCS decreased over the entire frequency range between 2.2 GHz and 3.4 GHz, in 3.2 GHz decrease from -23 dB to -26.9 dB, a 3.9 dB reduction in RCS at this frequency. The absorption factor of the reference antenna increased from 61% to 73%.
The optimization of phased-array RADAR areal coverage on the plane, in 2D, is considered for a semi-infinite strip where the agent carrying the RADAR travels at uniform velocity along the centerline of the strip. Because the system is symmetric we naturally are led to expect an optimal solution, with maximal areal coverage, which is symmetric and well ordered. However, in general, we find the optimal solution to be asymmetric and random in nature, defying intuition. An algorithm was developed for getting at these solutions and these optimal solutions are found to be far superior to ordered arrangements and random constructions. The conclusions are valid for other sensors modeled with 3D conical detection projected onto the plane.
