A Microfabricated Bandpass Filter with Coarse-Tuning and Fine-Tuning Ability Based on IPD Process and PCB Artwork

In this paper, a bandpass filter (BPF) was developed utilizing GaAs-based integrated passive device technology which comprises an asymmetrical spiral inductor and an interleaved array capacitor, possessing two tuning modes: coarse-tuning and fine-tuning. By altering the number of layers and radius of the GaAs substrate metal spheres, capacitance variation from 0.071 to 0.106 pF for coarse-tuning, and of 0.0015 pF for fine-tuning, can be achieved. Five air bridges were employed in the asymmetrical spiral inductor to save space, contributing to a compact chip area of 0.015λ0 × 0.018λ0. The BPF chip was installed on the printed circuit board artwork with Au bonding wire and attached to a die sink. Measured results demonstrate an insertion loss of 0.38 dB and a return loss of 21.5 dB at the center frequency of 2.147 GHz. Furthermore, under coarse-tuning mode, variation in the center frequency from 1.956 to 2.147 GHz and transmission zero frequency from 4.721 to 5.225 GHz can be achieved. Under fine-tuning mode, the minimum tuning value and the average tuning value of the proposed BPF can be accurate to 1.0 MHz and 4.7 MHz for the center frequency and 1.0 MHz and 12.8 MHz for the transmission zero frequency, respectively.

The Connection between Rf Anisotropy of Acoustically Excited NaCl Aqueous Solution and Debye Ionic Vibrational Potential

In this paper, we considered two phenomena in acoustically excited aqueous solutions of a strong electrolyte. These are the well-known Debye ionic vibrational potential (IVP), and radiofrequency anisotropy we discovered earlier , apparently, for the first time. Since both occur due to the accelerated motion of the solution, we have tried to combine them in one simple model. We have established that for a polarized UHF radio wave passed through a NaCl aqueous solution excited by an acoustic pulse the rotation angle of its vector E is proportional to the integral of the square of the observing IVP over time. An equivalent electrical circuit simulating the observed phenomena has been proposed and tested for physical feasibility. Several arguments are given in favour of the fluid-gyroscopic mechanism of RF anisotropy-related effects. We also found out that the IVP is practically independent of the vibrational velocity for frequencies below 10 kHz and it tends to zero at zero frequency. The latter is consistent with the law of conservation of energy but contradicts the incomplete existing theory.

Ontology Based Text Classifier for Information Extraction from Coronavirus Literature

The world is fighting an unprecedented coronavirus pandemic, and no country was prepared for it. Understanding the nature of this disease, when there is no available cure, is vital to encourage accurate clinical diagnosis and drug discovery prospects. When the amount of literature available is vast, it is important to represent the disease domain as completely as possible. The system should capture the morphology, semantics, syntax, and pragmatics of the given literature, in order to extract useful information. Also, building a classifier for a particular domain suffers from a zero frequency issue. To solve this effectively, latent topics are extracted and semantically represented in ontology to build a text classifier for coronavirus literature. The classifier is equipped with 2 components- ‘ontology’ and ‘machine learning data model’. Ontology helps to model the morphology and the semantic and pragmatic aspects of the text data through Latent Drichlet Allocation (LDA). It also preserves the contextual information in the document space, providing holistic feature representation facilities. To solve zero frequency and to extract actionable insights, a machine learning algorithm, Multi class Support Vector Machine (M-SVM), is incorporated with the ontology. It encodes features and achieves a classifier with highly discriminated classes. Further, to preserve contextual information space, and to enable data model formulation, the ontology is generated as a knowledge graph with their respective predefined classes. The resulting dataset can be used for clinical diagnosis and further research on the disease. Experimental results have shown that the proposed classifier outperforms the existing systems, with better domain representation. HIGHLIGHTS When the amount of literature available is vast, it is important to represent the disease domain as completely as possible. The system should capture the morphology, semantics, syntax, and pragmatics of the given literature, in order to extract useful information The classifier is equipped with 2 components- ‘ontology’ and ‘machine learning data model’. Ontology helps to model the morphology and the semantic and pragmatic aspects of the text data through Latent Drichlet Allocation (LDA). It also preserves the contextual information in the document space, providing holistic feature representation facilities To preserve contextual information space, and to enable data model formulation, the ontology is generated as a knowledge graph with their respective predefined classes. The resulting dataset can be used for clinical diagnosis and further research on the disease GRAPHICAL ABSTRACT

Investigation of principles of simulation of space-time processing of wideband signals

The paper states the principles of simulation of wideband signals applied in a surveillance radar. The resource of the radar model is analyzed with respect to sample rate of processed signals and required memory size as generated signals, noises, active and passive interferences demand a lot of memory. It is proposed to simulate only active intervals of operation of a pulse radar at zero frequency in the frequency domain.

Mass of Abrikosov vortex in high-temperature superconductor YBa$$_2$$Cu$$_3$$O$$_{7-\delta }$$

For more than four decades, mass of Abrikosov vortices defied experimental observations. We demonstrate a method of its detection in high-temperature superconductors. Similarly to electrons, fluxons circulate in the direction given by the magnetic field, causing circular dichroism. We report the magneto-transmittance of a nearly optimally doped thin YBa$$_2$$ 2 Cu$$_3$$ 3 O$$_{7-\delta }$$ 7 - δ film, measured using circularly polarized submillimeter waves. The circular dichroism emerges in the superconducting state and increases with dropping temperature. Our results confirm the dominant role of quasiparticle states in the vortex core and yield the diagonal fluxon mass of $$2.2 \times 10^8$$ 2.2 × 10 8 electron masses per centimeter at 45 K and zero-frequency limit, and even larger off-diagonal mass of $$4.9 \times 10^8 m_e$$ 4.9 × 10 8 m e /cm.

Investigating Interpersonal Meaning-Making in Indonesian EFL Learners' Writing: A Systemic Functional Perspective

This study presents an investigation of interpersonal meaning-making in students’ writing analytical exposition text. The objectives of this study are to describe the common mood types and to describe modality realization used in the text. Nine texts from 144 texts were collected to analyze. The theories from Systemic Functional Linguistics are adapted as the framework to analyze the clause of the text. The findings of this study showed that students have used mood types which can be seen in the use of subject and finite as mood elements, and the use of predicator, adjunct, and complement as residue. The arrangement of mood element ad residue shows the mood type they used. Regarding to SFL theories, the common mood type in this study is declarative as its function of analytical exposition text to discuss topic critically and deeply from one point of view. The result showed that students have attempted to provide information in the text. In the terms of modality, the median modality has a higher frequency in this text than that of high modality and low modality. It indicates that the students have an effort to position themselves and build the relationship to the reader in the text. Moreover, the zero frequency of low modality shows that the students did not provide opportunities for readers to doubt their position in the text. In conclusion, problem –solving approach as the pedagogical implication is appropriate for students to improve cognitive aspects in terms of communicative skills, so students have been able to create the effective analytical exposition text which is intended to discuss something critically from one point of view.

Free boundary methods and non-scattering phenomena

We study a question arising in inverse scattering theory: given a penetrable obstacle, does there exist an incident wave that does not scatter? We show that every penetrable obstacle with real-analytic boundary admits such an incident wave. At zero frequency, we use quadrature domains to show that there are also obstacles with inward cusps having this property. In the converse direction, under a nonvanishing condition for the incident wave, we show that there is a dichotomy for boundary points of any penetrable obstacle having this property: either the boundary is regular, or the complement of the obstacle has to be very thin near the point. These facts are proved by invoking results from the theory of free boundary problems.