Generation Of Zeros Research Articles

A deep generative model for feasible and diverse population synthesis

An agent-based model (ABM) simulates actions and interactions of the synthetic agents to understand the system-level behaviour. The synthetic population, the key input to ABM, mimics the distribution of the individual-level attributes in the actual population. Since individual-level attributes of the entire population are unavailable, small-scale samples are generally used for population synthesis. Synthesizing the population by directly sampling from the small-scale samples ignores the possible attribute combinations that are observed in the actual population but do not exist in the small-scale samples, called ‘sampling zeros’. A deep generative model (DGM) can potentially synthesize the sampling zeros but at the expense of falsely generating the infeasible attribute combinations that should be ‘zero’ in the generated data but exist, called ‘structural zeros’. This study proposes a novel method to ensure that the generation of structural zeros is minimal while recovering the ignored sampling zeros. Two loss functions for regularizing the DGMs are devised to customize the training and applied to a generative adversarial network (GAN) and a variational autoencoder (VAE). The adopted metrics for feasibility and diversity of the synthetic population indicate the capability of generating sampling and structural zeros – lower generation probability of structural zeros and lower generation probability of sampling zeros indicate the higher feasibility and the lower diversity, respectively. Results show that the proposed loss functions achieve considerable performance improvement in the feasibility and diversity of the synthesized population over traditional models. The proposed VAE additionally generated 23.5 % of the population ignored by the sample with 79.2 % precision (i.e., the generation ratio of structural zeros and the total samples is 20.8 %), while the proposed GAN generated 18.3 % of the ignored population with 89.0 % precision. The proposed improvement in DGM generates a more feasible and diverse synthetic population. Since synthesizing the population is the first stage of ABM, the proposed approach improves the overall accuracy of the ABM by circumventing the error propagation to later modelling stages.

Multi-band planar diplexers with sub-sets of frequency-contiguous transmission bands

AbstractA class of multi-band planar diplexer with sub-sets of frequency-contiguous transmission bands is reported. Such a radio frequency (RF) device is suitable for lightweight high-frequency receivers aimed at multi-band/multi-purpose mobile satellite communications systems. It consists of two channelizing filters, each of them being made up of the in-series cascade connection of replicas of a constituent multi-passband/multi-embedded-stopband filtering stage. This building filtering stage defines a multi-passband transfer function for each channel, in which each main transmission band is split into various sub-passbands by the multi-stopband part. In this manner, each split passband gives rise to several sub-passbands that are imbricated with their counterpart ones of the other channel. The theoretical RF operational principles of the proposed multi-band diplexer approach with sub-sets of imbricated passbands are detailed by means of a coupling–routing–diagram formalism. Besides, the generation of additional transmission zeros in each channelizing filter for higher-selectivity realizations by exploiting cross-coupling techniques into it is also detailed. Furthermore, for experimental demonstration purposes, a microstrip proof-of-concept prototype of second-order octo-band diplexer in the frequency range of 1.5–2.5 GHz that consists of two quad-band channelizing filters with pairs of imbricated passbands is developed and characterized.

Techniques for the generation of multiple additional transmission zeros in H-plane waveguide filters

AbstractIn this paper, different techniques for the generation of additional transmission zeros (TZs) in planar waveguide filters are investigated. In the classical theory, TZs are generated only by destructive interference of non-adjacent cavities, limiting the available number of TZs to the filter order itself. However, more approaches for the generation of TZs are known, including bypass-coupling in oversized cavities, frequency-dependent coupling apertures as well as dispersive/resonant TZs which can be realized by the direct source to load cross-coupling. The aim of this paper is to combine several of the strategies in one physical filter set-up to increase the maximal number of TZs beyond the filter order. Different Ku-band fourth-order filter set-ups are presented, showing in total between six and eight real as well as complex TZs. Three filters are manufactured as a proof of concept and compared with the simulation, showing very good agreement.

Stubbed Waveguide Cavity Filters

A new class of reduced-size waveguide filters implementing pseudoelliptic filtering functions is presented in this article. The basic structure of these filters is the stubbed waveguide cavity (SWC), which is proposed in both singleand double-stub configurations. The SWC consists of a main TE201 mode cavity, which is loaded with one or two E-plane stubs. The stubs behave as embedded half-mode cavities supporting additional resonant modes, and they are properly located so as to realize specific coupling schemes for the generation and control of transmission zeros. Depending on its configuration, a sole SWC can generate up to three poles and three transmission zeros. The design of higher order filters employing a cascade of SWCs, as well as combinations between SWCs and conventional waveguide cavities, are presented. The experimental results of a third-order filter employing one SWC (double-stub configuration) and a fifth-order filter employing two SWCs validate the feasibility of this new class of waveguide filters.

Folded W-Band Waveguide Filters with Resonant Coupling Apertures for the Generation of Additional Transmission Zeros

Abstract In this paper the realization of multiple additional transmission zeros in folded W-band waveguide filters is discussed. The transmission zeros (TZs) can be placed symmetrically as well as asymmetrically in the near passband region of the filter and arise due to a resonant coupling between source and / or load. Third and fourth order filter set-ups are presented, showing in total between three and six TZs. These zeros can be used to improve the selectivity of the filter without increasing the overall order. The filter design and realization process is discussed. Subsequently, the measurement results are compared with simulation, showing good agreement. As the filters are designed for the W-band, the manufacturing process is connected with some difficulties which are addressed within this paper as well.

Multi-Stub-Loaded Differential-Mode Planar Multiband Bandpass Filters

A new type of RF $/$ microwave differential-mode planar multiband bandpass filters (BPFs) are presented. Each symmetrical half of the proposed balanced filtering architecture is composed of the in-series cascade of $K$ $N$ -stub-loaded cells through $K-1$ inter-connection transmission-line segments to synthesize a differential-mode transfer function with $N$ $K$ th-order passbands. Additional features of this balanced multiband BPF topology are as follows: 1) generation of transmission zeros at both sides of all differential-mode passbands; 2) high common-mode power-rejection levels within the differential-mode passband ranges; 3) scalability to any number of arbitrary-order differential-mode transmission bands; and 4) lack of electromagnetic couplings in its physical structure. The theoretical foundations of the engineered balanced filter approach, along with guidelines to design the differential-mode transfer function and to attain optimum in-band common-mode power-attenuation characteristics, are expounded. Furthermore, for experimental-demonstration purposes, a third-order triple-band microstrip prototype with differential-mode passbands that are located within the range 1.4–3 GHz is manufactured and characterized.

A compact low insertion loss bandpass filter based on meandered self-coupled ring resonator

The traditional structure of dual mode bandpass filter is formed by a circular or rectangular resonator, which causes excessive circuit areas to be occupied. A 5.2 GHz bandpass filter, based on the triple-branch self-coupled ring resonator, is designed to achieve most essential features such as low insertion loss, compact size, and wide stopband. The coupling of each coupled branch introduces the even- and odd-mode perturbation, which produce sharp bandpass and wide stopband responses due to the generation of band-edge transmission zeros. The simulation and measurement in this paper are respectively verified by using IE3D electromagnetic simulator and Agilent's HP8722C network analyzer. Experimental results show that the filter has 19.2% bandwidth centered at 5.2 GHz, 1.2 dB insertion loss, 25 dB stopband rejection from 6 to 9 GHz. Moreover, the circuit size in this paper has been down to 9×6 mm 2 and can be applied to communication of microwave applications.

Propagating Waveguide Filters Using Dielectric Resonators

In this paper a new class of propagating waveguide in-line pseudoelliptic filters exploiting dielectric resonators is presented. The basic structure is a singlet, which is implemented by a ${\rm TE}_{01 \delta}$ mode dielectric resonator placed into a rectangular waveguide above cutoff. Couplings are controlled by a proper positioning of the puck. The fundamental propagating mode of the waveguide is exploited to both excite and bypass the resonator so as to obtain bypass coupling capability, allowing the generation of transmission zeros. Higher order filters are obtained by cascading singlets through quarter-wave or half-wave waveguide sections. The quarter-wave section behaves as an admittance inverter, while the half-wave section behaves as a resonator, the latter resulting in filters which combine dielectric and cavity resonators. Thanks to this combination, unique performances such as wide bandwidth and sharp transition bands can be obtained. To validate the proposed method a third-order filter with 2.3% fractional bandwidth (FBW) and a fifth-order filter with 8.15% FBW have been designed and manufactured, thus demonstrating the approach feasibility.

Low-Pass and Bandpass Filters With Ultra-Broad Stopband Bandwidth Based on Directional Couplers

The design of planar sharp-rejection low-pass and bandpass filters (LPFs and BPFs) featuring a very broad stopband is addressed in this paper. For the LPF case, two new classes of bandstop signal-interference transversal filtering section (TFS) consisting of power directional couplers in reflection mode are proposed. In the BPF application, additional short-circuit stubs are inserted at the TFS input/output accesses. Based on these filtering cells, the devised LPF and BPF approaches are then derived from the cascade of multiple TFSs with frequency-contiguous stopbands. Thus, an overall attenuated band showing an ultra-large spectral width and deep rejection levels through the generation of several transmission zeros (TZs) is synthesized. Furthermore, such unprecedented filtering performances are obtained for much lower circuit complexity than available solutions. The operating principle of the conceived LPF and BPF topologies and guidelines for their realization are detailed. This includes formulas for their analytically designable TZs. For practical validation, three LPF prototypes and one wideband BPF circuit are also fabricated in microstrip technology and tested.

Novel Reconfigurable Defected Ground Structure Resonator on Coplanar Waveguide

A novel reconfigurable defected ground structure (DGS) resonator fabricated on coplanar waveguide (CPW) technology is presented. The resonator is endowed with an original design which enables the generation of multiple transmission zeros at arbitrary frequencies. The chosen design is indeed based on a slot defect created on the lateral ground planes of the CPW with the double advantage to allow a simple reconfiguration, by means of surface mounted (or fabricated) components, and a very compact solution, by exploiting the transversal dimension of the coplanar wave transmission line (CPW-TL). Four different states of the diodes configuration are investigated, where in each state multiple transmission zeros are produced in the frequency range from 1 GHz to 11 GHz. The equivalent circuit of each state is obtained using a conventional circuit parameter extraction method. Moreover, the slotline design equations are used to identify the transmission zeros and validated using the magnetic field distribution inside the slot. In this work, the reconfigurability is first proven by means of short bridges mounted in specific locations. These bridges are then replaced by PIN diodes. Simulated and measured results are in good agreement.

Reconfigurable defected ground structure cell using PIN diodes on Coplanar Waveguide technology

AbstractThis article addresses a novel reconfigurable defected ground structure resonator fabricated on Coplanar Waveguide (CPW) technology. The resonator is endowed with an original design that enables the generation of multiple transmission zeros at arbitrary frequencies. The chosen design is indeed based on a slot defect created on the lateral ground planes of the CPW with the double advantage to allow a simple reconfiguration, by means of surface mounted (or fabricated) components, and a compact solution, by exploiting the transversal dimension of the CPW. Three different states of the diodes configuration are investigated, where in each state multiple transmission zeros are produced in the frequency range from 1 GHz to 11 GHz. Slotline design equations are used to identify the resonant frequencies of the transmission zeros and validated using the magnetic field distribution inside the slot. In this work, the reconfigurability is first proven by means of open and short circuits in specific locations and then replaced by PIN diodes. Simulated and measured results are in good agreement. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 766–770, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25003

Dissipation caused by a vorticity field and generation of singularities in Madelung fluid

We consider a generalization of Madelung fluid equations, which was derived in the 1980s by means of a pathwise stochastic calculus of variations with the classical action functional. At variance with the original ones, the new equations allow us to consider velocity fields with vorticity. Such a vorticity causes dissipation of energy and it may concentrate, asymptotically, in the zeros of the density of the fluid. We study, by means of numerical methods, some Cauchy problems for the bidimensional symmetric harmonic oscillator and observe the generation of zeros of the density and concentration of the vorticity close to central lines and cylindrical sheets. Moreover, keeping the same initial data, we perturb the harmonic potential by a term proportional to the density of the fluid, thus obtaining an extension with vorticity of the Gross–Pitaevskii equation, and observe analogous behaviours.

A circuit model of probes in dual-mode cavities

An accurate model of coaxial probes used as input and output ports in dual-mode cavities (either air-filled or dielectric-loaded) is presented. The model precisely predicts such empirically observed phenomena as limited out-of-band isolation, generation of extra transmission zeros, and asymmetric responses. The model parameters can be determined from simple measured data. It is shown how the model can be used in the analysis and synthesis of canonical dual-mode filters. Experimental verification of the model for several configurations showed excellent agreement with theory. >

Rigorous Design Of Dielectric Resonator FiltersApplying The Finite Element Method

Numerical techniques permit now to analyze rigorously complex voluminous ar planar microwave devices. In this paper, a rigorous design of dielectric resonator filters applying the finite element method is described. We first present a dual mode coupling technique which replaces classical dielectric resonators, coupling and tuning screws commonly used in dual mode filters, by slotted dielectric resonators. Next, to explain the generation of transmission zeros in the insertion loss performance of microwave filters, we define a new theoretical analysis based on the contribution of the first dielectric resonator hybrid mode and of higher order modes. This analysis can be applied to any type of microwave dual mode filter. Finally, a synthesis method applying the finite element method, is developed to design rigorously for the first time, a four and a eight pole slotted dielectric resonator elliptic filters. The experimental results obtained with no tuning and the theoretical ones show good agreement.