Characterization of Low Frequency Combustion Dynamics of Hot Blast Stoves by Means of a Flame Transfer Function Based on CFD Forced Response Simulations: Comparison of Different Hot Blast Stove Designs

2015 ◽  
Author(s):  
Simon Gövert ◽  
Virginia Fratalocchi ◽  
Jim B. W. Kok
Keyword(s):  
Transfer Function ◽  
Mass Flow ◽  
Forced Response ◽  
Computational Time ◽  
Band Pass Filter ◽  
Computational Domain ◽  
Frequency Range ◽  
Pass Filter ◽  
Combustion Dynamics ◽  
Hot Blast

The combustion dynamics of thermo-acoustic systems like gas turbine combustors at elevated pressure and atmospheric industrial furnaces can be studied using a forced response approach. In this approach, the flame is excited by external perturbation of the upstream fuel or air mass flow. The flame transfer function can then be determined, which describes the response of the heat release rate in the combustor or furnace to the upstream velocity fluctuations. Subsequently, the flame transfer function can be used as an input for acoustic network models to further analyze the stability behavior of a given combustion system. Most of the applications of the flame transfer function analysis are for natural gas fired systems with dimensions such, that most of the relevant combustion dynamics is in the frequency range 100–500 Hz. The situation is different for hot blast stoves as used in the iron making process. Here the fuel is low calorific coal gas and the dimensions of the stove are huge, with heights of 30 m at a diameter of 5 m. This leads to a relevant frequency range for the combustion dynamics in interaction with acoustics of about 3–80 Hz. In order to cope with this combination of a large computational domain and extreme low frequent combustion dynamics in the response simulation, special attention was devoted to computational efficiency. In order to allow for a sufficient mesh resolution to capture the combustion characteristics while keeping the computational demands in a feasible range, the computational domain is to be drastically reduced by the use of symmetry assumptions. In a first step, the mesh dependency is studied and different combustion models are analyzed for a reference geometry on the basis of steady states results. The burning velocity model with adapted laminar flame speed description is subsequently chosen for the transient simulations. Transient numerical simulations are performed using a URANS turbulence model. The combustor is excited by a multi-harmonic perturbation of the fuel mass flow, to further reduce computational time. The flame transfer function is determined and compared for two different burner designs. The results show significant impact of combustor design on the acoustic behavior and combustion time scales. While the reference design acts like a low pass filter with a cut-off frequency of about 6 Hz, the modified design shows band-pass filter characteristics with a lower and higher cut-off frequency of 30 and 60 Hz, respectively.

Density-based discrimination of protein and RNA in the ribosome

1992 ◽  
Vol 50 (1) ◽  
pp. 464-465
Author(s):  
Joachim Frank
Keyword(s):  
Transfer Function ◽  
Spatial Frequency ◽  
Three Dimensional ◽  
Wiener Filter ◽  
Dark Field Image ◽  
Dark Field ◽  
Frequency Range ◽  
Bright Field ◽  
Contrast Transfer Function ◽  
Pass Filter

Cryo-electron microscopy combined with single-particle reconstruction techniques has allowed us to form a three-dimensional image of the Escherichia coli ribosome.In the interior, we observe strong density variations which may be attributed to the difference in scattering density between ribosomal RNA (rRNA) and protein. This identification can only be tentative, and lacks quantitation at this stage, because of the nature of image formation by bright field phase contrast. Apart from limiting the resolution, the contrast transfer function acts as a high-pass filter which produces edge enhancement effects that can explain at least part of the observed variations. As a step toward a more quantitative analysis, it is necessary to correct the transfer function in the low-spatial-frequency range. Unfortunately, it is in that range where Fourier components unrelated to elastic bright-field imaging are found, and a Wiener-filter type restoration would lead to incorrect results. Depending upon the thickness of the ice layer, a varying contribution to the Fourier components in the low-spatial-frequency range originates from an “inelastic dark field” image. The only prospect to obtain quantitatively interpretable images (i.e., which would allow discrimination between rRNA and protein by application of a density threshold set to the average RNA scattering density may therefore lie in the use of energy-filtering microscopes.

Application of communication network theory to the electromagnetic seismograph

1964 ◽  
Vol 54 (5A) ◽  
pp. 1479-1489
Author(s):  
S. Dopp
Keyword(s):  
Communication Network ◽  
Transfer Function ◽  
Equivalent Circuit ◽  
Network Theory ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Electromagnetic Seismograph ◽  
Band Pass

Abstract Communication network theory is applied to the equivalent circuit of the electromagnetic seismograph. The seismograph's transfer function is derived in the general case of an arbitrary linear passive coupling network between pendulum and galvanometer. Examples are given, one of which refers to the construction of a band-pass filter in the form of a lattice of filter galvanometers.

scholarly journals Design of UWB Filter with WLAN Notch

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
Harish Kumar ◽  
MD. Upadhayay
Keyword(s):  
Circuit Simulation ◽  
Ground Plane ◽  
Stop Band ◽  
Simulation Software ◽  
Pass Band ◽  
Area Network ◽  
Band Pass Filter ◽  
Frequency Range ◽  
Pass Filter ◽  
Band Pass

UWB technology- (operating in broad frequency range of 3.1–10.6 GHz) based filter with WLAN notch has shown great achievement for high-speed wireless communications. To satisfy the UWB system requirements, a band pass filter with a broad pass band width, low insertion loss, and high stop-band suppression are needed. UWB filter with wireless local area network (WLAN) notch at 5.6 GHz and 3 dB fractional bandwidth of 109.5% using a microstrip structure is presented. Initially a two-transmission-pole UWB band pass filter in the frequency range 3.1–10.6 GHz is achieved by designing a parallel-coupled microstrip line with defective ground plane structure using GML 1000 substrate with specifications: dielectric constant 3.2 and thickness 0.762 mm at centre frequency 6.85 GHz. In this structure aλ/4 open-circuited stub is introduced to achieve the notch at 5.6 GHz to avoid the interference with WLAN frequency which lies in the desired UWB band. The design structure was simulated on electromagnetic circuit simulation software and fabricated by microwave integrated circuit technique. The measured VNA results show the close agreement with simulated results.

A Narrow Band Pass Filter Using Technology Surface Mount Technology on Radar Frequency Generators

2016 ◽  
Vol 3 (1) ◽  
pp. 136
Author(s):  
I Dewa Putu Hermida ◽  
Deni Permana Kurniadi ◽  
Iqbal Syamsu
Keyword(s):  
Stop Band ◽  
Band Width ◽  
Signal Frequency ◽  
Band Pass Filter ◽  
Frequency Range ◽  
Pass Filter ◽  
Fmcw Radar ◽  
Frequency Generator ◽  
Band Depth ◽  
Radar Frequency

A BPF using SMT components. A cut-off frequency on a filter under cooling below LPF which works at  freq 310 MHz, while the cut-off frequency below a filter under cooling HPF which works at freq 306 MHz, so that the width of the band This filter is a type of narrow bandwidth filter 4 MHz. An 7 poles filter order with the aim to increase the steepness of the filter is generated, using the elliptic filter family or causer. Stop band width (Fs) to filter under cooling below about 20% in the frequency range 372 MHz, with stop band depth (As) of about 55 dB, while the stop band width (Fs) to filter under cooling of about 20% in the frequency range 245 MHz, with stop band depth (As) of about 55 dB. This filter is designed to pass the signal frequency division results DRO with a CF of 9856 MHz. Using SMT components, this circuit becomes very small and compact and has a high Q. The results of the simulation are generated, then this filter can realized system FMCW radar frequency generator.

Design and Simulation of Photoelectric Detection Circuit for Microfluidics Chip

2013 ◽  
Vol 380-384 ◽  
pp. 3300-3303
Author(s):  
Ming Yuan Ren ◽  
Li Tian ◽  
Wei Wang ◽  
Xiao Wei Liu ◽  
Zhi Gang Mao
Keyword(s):  
Transfer Function ◽  
Detection System ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Photoelectric Detection ◽  
Detection Circuit ◽  
Band Pass ◽  
Simulation Results ◽  
Integrated Microfluidics

This paper presents a photoelectric detection circuit for microfluidics chip. The proposed photoelectric detection system can reduce noise and increase sensitivity. It is consist of pre-amplifier, ac-amplifier and band-pass filter. The transfer function of photoelectric detection circuit is introduced. The circuit implementations and simulation results are given. The proposed photoelectric detection circuit is suitable for integrated microfluidics chip.

scholarly journals Novel Resonant Structure to Compact Partial H-Plane Band-Pass Waveguide Filter

2017 ◽  
Vol 7 (1) ◽  
pp. 266
Author(s):  
Elahe Mohhamadi ◽  
Habib Ghorbaninejad
Keyword(s):  
Cross Section ◽  
Design Procedure ◽  
Band Pass Filter ◽  
Frequency Range ◽  
Resonant Structure ◽  
Pass Filter ◽  
Section Size ◽  
Longitudinal Length ◽  
Band Pass ◽  
Waveguide Filter

In this paper partial H-plane band-pass waveguide filter, utilizing a novel resonant structure comprising a metal window along with metal posts has been proposed to compact the filter size. The metal windows and posts have been implemented transversely in a partial H-plane waveguides, which have one-quarter cross section size compared to the conventional waveguides in the same frequency range. Partial H-plane band-pass waveguide filter with novel proposed resonant structures has considerably shorter longitudinal length compared to the conventional partial H-plane filters, so that they reduce both cross section size and the total length of the filter compared to conventional H-plane filters, in the same frequency range. In the presented design procedure, the size and shape of each metal window and metal posts has been determined by fitting the transfer function of the proposed resonant structure to that of a desired one, which is obtained from a suitable equivalent circuit model. The design process is based on optimization using electromagnetic simulator software, HFSS. A proposed partial H-plane band-pass filter has been designed and simulated to verify usefulness and performance of the design method.

scholarly journals Filtering Sinyal Menggunakan Band Pass Filter

2019 ◽  
Vol 1 (1) ◽  
pp. 66-69
Author(s):  
Ayu Novira
Keyword(s):  
Sound Quality ◽  
Musical Instruments ◽  
Analog Filters ◽  
Band Pass Filter ◽  
Frequency Range ◽  
Pass Filter ◽  
Iir Filter ◽  
Recorded Sound ◽  
Solid Objects ◽  
Band Pass

Sound is a signal or wave that propagates with a certain frequency and amplitude through intermediary media that are delivered such as water, air and solid objects. Humans can communicate with other humans with sound. But the sound that is released by humans, musical instruments, or other objects does not always sound clear and good, some of the recorded sound has a lot of noise which makes the sound quality is disturbed and not good. The solution for making sound in an object better and cleaner is filtering. [2]. Filters can be interpreted as a circuit that passes a certain frequency band desired and dampens other frequency bands. Filters are divided into two types, namely analog filters and digital filters. According to the impulse response the digital filter is divided into two, namely the Infinite Impulse Filter (IIR) filter and the Finite Impulse Filter (FIR) filter. In this study a filtering process will be carried out on the sound of the guitar. The filter used is the Band Pass Filter, a filter that can be used to isolate or filter certain frequencies in a particular band or frequency range.

Compact multiple electromagnetic band gap (EBG) cells based ultra wide band (UWB) filter with improved stop-band characteristics

Circuit World ◽  
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Masood Molimoli Hajamohideen ◽  
Sreeja Balakrishanapillai Suseela
Keyword(s):  
Stop Band ◽  
Wide Band ◽  
Ultra Wide Band ◽  
Pass Band ◽  
Band Pass Filter ◽  
Frequency Range ◽  
Pass Filter ◽  
Electromagnetic Band Gap ◽  
Content Type ◽  
Band Pass

Purpose The purpose of the study is – in Microwave filter design, the performances of passive components are deteriorated by parasitics at gigahertz (GHz) frequency range. A compact and multi-stack electromagnetic band gap (EBG) structure is proposed with improved stop band characteristics at GHz frequency range in this work. This paper proposes a new design for ultra wide band pass filter (resonator BPF) with periodically loaded one-dimensional EBG to achieve the harmonic suppression. This basic EBG structure is developed with combination of a signal strip and ground plane in the slotted section. The resonator BPF is loaded with one EBG, two EBG and three EBGs to improve the stop-band rejection. Design/methodology/approach The proposed filter is with multi-stack EBG cell for achieving good pass band and stop bands performance. Circuit model is analyzed in Section 2. Section 3 discuses band pass filter loaded with one EBG. In Sections 4 and 5, filter with two and three EBG loaded resonators are discussed, respectively. Section 6 is concluded with comparison of simulation and measured results. Findings The stop-band rejection is 20 dB, 40 dB and 50 dB, respectively, in the frequency range of 6 GHz to 20 GHz. The simulation analysis is carried out with advanced system design software. To validate the simulation results, proposed structure is fabricated, and results are found to be in good agreement. Originality/value This paper accounts for designing resonator BPF, which has slow wave pass band and stop band characteristics. Second and third harmonics are suppressed using multi-stack EBG. Various stacks with basic designs are proposed and improved results have been demonstrated which is open for future research.

scholarly journals Dendrite-to-Soma Input/Output Function of Continuous Time-Varying Signals in Hippocampal CA1 Pyramidal Neurons

2007 ◽  
Vol 98 (5) ◽  
pp. 2943-2955 ◽  
Author(s):  
Erik P. Cook ◽  
Jennifer A. Guest ◽  
Yong Liang ◽  
Nicolas Y. Masse ◽  
Costa M. Colbert
Keyword(s):  
Pyramidal Neurons ◽  
Gain Control ◽  
Linear Filter ◽  
Band Pass Filter ◽  
Time Varying ◽  
Input Output ◽  
Frequency Range ◽  
Pass Filter ◽  
Ca1 Pyramidal Neurons ◽  
Band Pass

We examined how hippocamal CA1 neurons process complex time-varying inputs that dendrites are likely to receive in vivo. We propose a functional model of the dendrite-to-soma input/output relationship that combines temporal integration and static-gain control mechanisms. Using simultaneous dual whole cell recordings, we injected 50 s of subthreshold and suprathreshold zero-mean white-noise current into the primary dendritic trunk along the proximal 2/3 of stratum radiatum and measured the membrane potential at the soma. Applying a nonlinear system-identification analysis, we found that a cascade of a linear filter followed by an adapting static-gain term fully accounted for the nonspiking input/output relationship between the dendrite and soma. The estimated filters contained a prominent band-pass region in the 1- to 10-Hz frequency range that remained constant as a function of stimulus variance. The gain of the dendrite-to-soma input/output relationship, in contrast, varied as a function of stimulus variance. When the contribution of the voltage-dependent current Ih was eliminated, the estimated filters lost their band-pass properties and the gain regulation was substantially altered. Our findings suggest that the dendrite-to-soma input/output relationship for proximal apical inputs to CA1 pyramidal neurons is well described as a band-pass filter in the theta frequency range followed by a gain-control nonlinearity that dynamically adapts to the statistics of the input signal.

Gravity anomaly separation by Wiener filtering

Geophysics ◽  
1990 ◽  
Vol 55 (5) ◽  
pp. 539-548 ◽  
Author(s):  
R. S. Pawlowski ◽  
R. O. Hansen
Keyword(s):  
Transfer Function ◽  
Power Spectrum ◽  
Gravity Anomaly ◽  
Wiener Filtering ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Paradox Basin ◽  
Spectral Overlap ◽  
Gravity Signal ◽  
Wavelength Filtering

We introduce a gravity anomaly separation method based on frequency‐domain Wiener filtering. Gravity anomaly separation can be effected by such wavelength filtering when the gravity response from the geologic feature of interest (the signal) dominates one region (or spectral band) of the observed gravity field’s power spectrum. The Wiener filter is preferable to a conventional band‐pass filter because geologic information from the study area can be incorporated to a greater extent in specifying the filter’s transfer function. Our method differs from previous Wiener filtering schemes in that it provides, through direct modeling of known geology (e.g., outcrop and borehole data), a more objective estimate of the signal power spectrum required for defining the transfer function of the filter. We illustrate the technique first with synthetic data, and then with a field example from the southern Paradox basin. The Paradox basin example reveals the limitation inherent to all wavelength filtering which results from spectral overlap between the gravity signal and the spectral contributions of other geologic sources. In the study area, significant spectral overlap occurs between the gravity effects of sources in the Precambrian basement and the gravity signal arising from the density contrast across the Mississippian‐Pennsylvanian interface.

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