scholarly journals Retrieval of static stability parameter from the radiosonde/rawinsonde ascent rate profiles: a wavelet approach

2009 ◽  
Vol 27 (2) ◽  
pp. 547-553 ◽  
Author(s):  
Prakash M. Dolas ◽  
Karanam Kishore Kumar
Keyword(s):  
Wavelet Transforms ◽  
Atmospheric Temperature ◽  
Static Stability ◽  
Present Communication ◽  
Basic Premise ◽  
Ascent Rate ◽  
Novel Method ◽  
Rate Profile ◽  
Radiosonde Ascent ◽  
Good Agreement

Abstract. In the present communication a novel method is presented to derive the altitude profile of Brunt-Väisälä period from the ascent rate profile of sounding balloons. The basic premise of the present method is that the oscillations in the ascent rate of the balloon will have the signature of Brunt-Väisälä frequency, which can be retrieved by using sophisticated spectral tools. We employ wavelet transforms to arrive at the Brunt-Väisälä period profile. Comparison of retrieved Brunt-Väisälä periods with the values derived from the temperature data available from the same radiosonde ascent shows good agreement. Retrieving the atmospheric temperature from the height profile of Brunt-Väisälä period is also discussed in the present communication. We have shown that it is possible to estimate the Brunt-Väisälä period and temperature profiles from the rawinsonde ascent rate data alone where temperature sounding is not available.

scholarly journals A Compact Wideband SIW Bandpass Filter with Wide Stopband and High Selectivity

Electronics ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 440 ◽  
Author(s):  
Huang ◽  
Yuan
Keyword(s):  
High Selectivity ◽  
Bandpass Filter ◽  
Cutoff Frequency ◽  
Ring Resonators ◽  
Fractional Bandwidth ◽  
Split Ring ◽  
Electromagnetic Band Gap ◽  
Compact Size ◽  
Novel Method ◽  
Good Agreement

A novel method to design a wideband substrate integrated waveguide (SIW) bandpass filter (BPF) with compact size, wide stopband and high selectivity is presented. In this method some unique electromagnetic band-gap (EBG) cells are periodically etched on the top layer of SIW to realize a wide passband propagating below the equivalent waveguide cutoff frequency. By changing the configuration of EBG cells, undesired harmonics in upper stopband can be suppressed and a wideband BPF with wide stopband can be obtained. By symmetrically loading two complementary split ring resonators (CSRRs) on the tapered gradient lines of the input/output ports, a transmission zero near the passband can be introduced, and it makes the frequency selectivity of upper sideband improve significantly. As a verification, a wideband SIW BPF with a 3.02 GHz absolute bandwidth (ABW) and a 64.7% fractional bandwidth (FBW) centered at 4.67 GHz is designed, simulated, manufactured, and measured. The results of the experiment and simulation are in good agreement.

scholarly journals Opposite Long-term Trends in Aerosols between Lower and Higher Altitudes: A Testimony to the Aerosol-PBL Feedback

2017 ◽  
Author(s):  
Zipeng Dong ◽  
Zhanqing Li ◽  
Xing Yu ◽  
Maureen Cribb ◽  
Xingmin Li ◽  
...  
Keyword(s):  
Air Pollution ◽  
Atmospheric Temperature ◽  
Lower Atmosphere ◽  
Aerosol Loading ◽  
Wide Range ◽  
Atmospheric Temperature Profile ◽  
Long Term Trends ◽  
Novel Method ◽  
Absorbing Aerosols ◽  
The Stability

Abstract. Interactions between absorbing aerosols and the planetary boundary layer (PBL) play an important role in enhancing air pollution near the surface. In this study, a unique feature of the interaction is found that has important implications in monitoring and combating air pollution. Opposite trends in aerosol loading between the lower and upper PBL are found on a wide range of time scales and from different types of data acquired by various platforms: from a short-term field experiment to decadal satellite observations, and multi-decadal ground observations in China. A novel method is proposed to obtain the vertical profiles of aerosol loading from passive sensors by virtue of varying elevations. Trend analyses of three particulate variables having different temporal scales, namely, visibility, aerosol optical depth, and extinction, all exhibit the same trend: increasing at the lower atmosphere, but decreasing in the upper. Column-integrated quantities are much less variable. The reversal trend is consistent with the strong vertical gradients in the aerosol-induced atmospheric heating rate that unevenly modifies the atmospheric temperature profile and alters the stability differently. These findings have multiple implications in understanding and combating air pollution, especially in many developing countries producing large amounts of black and brown carbon aerosols.

scholarly journals High Selectivity Dual-Band Bandpass Filter with Tunable Lower Passband

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Wei-Qiang Pan ◽  
Xiao-Lan Zhao ◽  
Yao Zhang ◽  
Jin-Xu Xu
Keyword(s):  
High Selectivity ◽  
Bandpass Filter ◽  
Bandpass Filters ◽  
Dual Band ◽  
Transmission Zeros ◽  
Resonant Modes ◽  
Novel Method ◽  
Good Agreement ◽  
Tunable Bandpass Filter

This paper presents a novel method to design dual-band bandpass filters with tunable lower passband and fixed upper passband. It utilizes a trimode resonator with three controllable resonant modes. Discriminating coupling is used to suppress the unwanted mode to avoid the interference. Varactors are utilized to realize tunable responses. The bandwidth of the two bands can be controlled individually. Transmission zeros are generated near the passband edges, resulting in high selectivity. For demonstration, a tunable bandpass filter is implemented. Good agreement between the prediction and measurement validates the proposed method.

Chaotic Vibrations of Sector-Type Spherical Shells

2008 ◽  
Vol 3 (4) ◽  
Author(s):  
A. V. Krysko ◽  
J. Awrejcewicz ◽  
I. V. Papkova
Keyword(s):  
Nonlinear Dynamics ◽  
Chaotic Dynamics ◽  
Static Stability ◽  
Control Parameters ◽  
Spherical Shells ◽  
Spherical Cap ◽  
Chaotic Vibrations ◽  
Novel Method ◽  
Sector Type ◽  
Mechanical Objects

In this work, chaotic vibrations of shallow sector-type spherical shells are studied. A sector-type shallow shell is understood as a shell defined by a sector with associated boundary conditions and obtained by cutting a spherical shell for a given angle θk, or it is a sector of a shallow spherical cap associated with the mentioned angle. Both static stability and complex nonlinear dynamics of the mentioned mechanical objects subjected to transversal uniformly distributed sign-changeable load are analyzed, and the so-called vibration charts and scales regarding the chosen control parameters are reported. In particular, scenarios of transition from regular to chaotic dynamics of the mentioned shells are investigated. A novel method to control chaotic dynamics of the studied flexible spherical shells driven by transversal sign-changeable load via synchronized action of the sign-changeable antitorque is proposed and applied. All investigations are carried out within the fields of qualitative theory of differential equations and nonlinear dynamics.

scholarly journals Estimation of unsteady aerodynamic forces using pointwise velocity data

2016 ◽  
Vol 804 ◽  
Author(s):  
F. Gómez ◽  
A. S. Sharma ◽  
H. M. Blackburn
Keyword(s):  
Aerodynamic Force ◽  
Mean Flow ◽  
Time Resolved ◽  
Time Stepping ◽  
Unsteady Aerodynamic ◽  
Novel Method ◽  
Unsteady Aerodynamic Force ◽  
Lift And Drag ◽  
Matrix Free ◽  
Good Agreement

A novel method to estimate unsteady aerodynamic force coefficients from pointwise velocity measurements is presented. As opposed to other existing methodologies, time-resolved full velocity fields are not required. The methodology is based on a resolvent-based reduced-order model which requires the mean flow to obtain physical flow structures and pointwise measurement to calibrate their amplitudes. A computationally affordable time-stepping methodology to obtain resolvent modes in non-trivial flow domains is introduced and compared with previous existing matrix-free and matrix-forming strategies. The technique is applied to the unsteady flow around an inclined square cylinder at low Reynolds number. The potential of the methodology is demonstrated through good agreement between the fluctuating pressure distribution on the cylinder and the temporal evolution of the unsteady lift and drag coefficients predicted by the model and those computed by direct numerical simulation.

Fault Location of Transmission Line Based on Discrete Wavelet Transforms

2011 ◽  
Vol 121-126 ◽  
pp. 1269-1273
Author(s):  
Wen Xiu Tang ◽  
Mo Zhang ◽  
Ying Liu ◽  
Xu Fei Lang ◽  
Liang Kuan Zhu
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Wavelet Transforms ◽  
Fault Location ◽  
Short Circuit ◽  
Signal Transmission ◽  
Transient Signal ◽  
Discrete Wavelet ◽  
Novel Method ◽  
Non Stationary Signal

In this paper, a novel method is investigated to detect short-circuit fault signal transmission lines in strong noise environment based on discrete wavelet transform theory. Simulation results show that the method can accurately determine the fault position, can effectively analyze the non-stationary signal and be suitable for transmission line fault occurred after transient signal detection. Furthermore, it can effectively eliminate noise effects of fault signal so as to realize the transmission lines of accurate fault.

scholarly journals Shear-induced particle diffusivities from numerical simulations

2001 ◽  
Vol 443 ◽  
pp. 101-128 ◽  
Author(s):  
MARCO MARCHIORO ◽  
ANDREAS ACRIVOS
Keyword(s):  
Ensemble Averaging ◽  
Stokesian Dynamics ◽  
System Of Particles ◽  
Novel Method ◽  
The Mean ◽  
Dynamics Simulations ◽  
Neutrally Buoyant ◽  
Solid Spheres ◽  
Good Agreement ◽  
Number Of Particles

Using Stokesian dynamics simulations, we examine the flow of a monodisperse, neutrally buoyant, homogeneous suspension of non-Brownian solid spheres in simple shear, starting from a large number of independent hard-sphere distributions and ensemble averaging the results. We construct a novel method for computing the gradient diffusivity via simulations on a homogeneous suspension and, although our results are only approximate due to the small number of particles used in the simulations, we present here the first values of this important parameter, both along and normal to the plane of shear, to be obtained directly either experimentally or numerically. We show furthermore that, although the system of equations describing the particle motions is deterministic, the particle displacements in the two directions normal to the bulk flow have Gaussian distributions with zero mean and a variance which eventually grows linearly in time thereby establishing that the system of particles is diffusive. For particle concentrations up to 45%, we compute the corresponding tracer diffusivities both from the slope of the mean-square particle displacement and by integrating the corresponding velocity autocorrelations and find good agreement between the two sets of results.

scholarly journals Determination of initial velocities of enzymic reactions from progress curves

1986 ◽  
Vol 237 (3) ◽  
pp. 821-825 ◽  
Author(s):  
R Dagys ◽  
A Pauliukonis ◽  
D Kazlauskas ◽  
M Mankevicius ◽  
R Simutis
Keyword(s):  
Initial Velocity ◽  
Experimental Error ◽  
Spline Function ◽  
Present Communication ◽  
Time Value ◽  
Substrate Conversion ◽  
Novel Method ◽  
Cubic Spline Function ◽  
Large Experimental Error

The present communication describes a novel method for estimating initial velocities (v) of enzyme-catalysed reactions. It is based on an approximation of experimental data obtained by the cubic spline function. The initial velocity of a reaction is calculated as a derivative of the approximating function at a time value equal to zero. The proposed method is usable on a computer with a FORTRAN IV program. The method can be successfully used in such cases as substantial extents of substrate conversion, the inactivation of an enzyme in the course of a reaction, the existence of large experimental error or when the reaction mechanism is unknown.

scholarly journals PDMS Soft Skin Device with Deformable Micro-Diaphragm Array Fabricated with Rapid Substrate-Releasing Process

2020 ◽  
Vol 32 (2) ◽  
pp. 289-296
Author(s):  
Hideyuki Mitsui ◽  
Hiroshi Kashiwazaki ◽  
Takashi Mineta ◽  
◽  
Keyword(s):  
Contact Angle ◽  
Sacrificial Layer ◽  
High Surface ◽  
Surface Hydrophobicity ◽  
Inner Pressure ◽  
Novel Method ◽  
Fabrication And Characterization ◽  
Releasing Process ◽  
Good Agreement

This paper describes the fabrication and characterization of a prototype wettability switching soft skin device that dynamically switches its surface morphology between flat and rough states. The device, which consists of a 1-μm-thick polydimethylsiloxane (PDMS) deformable diaphragm on a PDMS substrate with a micro-bump arrays, was successfully formed with a high fabrication yield by a novel method of device releasing from a dummy substrate. In buffered hydrofluoric acid (BHF) solution, a sacrificial layer of a novolak-resin-based resist was able to be rapidly released from the OH-terminated SiO2 surface of the dummy substrate, probably due to the breaking of hydrogen bonds at the interface. The wettability of the fabricated device was reversibly switched using micro-diaphragm deformation by varying the inner pressure. When a droplet was placed on the surface in the rough state, a large contact angle of approximately 140° was obtained, close to the Cassie mode with air in the concave-deformed PDMS micro-diaphragms, which indicated a high surface hydrophobicity. During cyclic switching between the rough and flat states after second switching, the contact angle reversibly changed between 106° and 120°, in good agreement with the Wenzel mode, where the micro-diaphragm surfaces were fully wet. Additionally, we observed that the droplet did not move even on the tilted device.

scholarly journals Thermodynamic model for a pilot balloon

2021 ◽  
Author(s):  
Vicent Favà ◽  
Juan José Curto ◽  
Alba Gilabert
Keyword(s):  
Thermodynamic Model ◽  
Ground Level ◽  
Atmospheric Temperature ◽  
Lapse Rate ◽  
Temperature Lapse Rate ◽  
Ascent Rate ◽  
Pilot Balloon ◽  
The Us ◽  
Optical Theodolite

Abstract. In the early part of the 20th century, tracking a pilot balloon from the ground with an optical theodolite was one of the few methods that was able to provide information from the upper air. One of the most significant sources of error with this method, however, was involved in calculating the balloon height as a function of time, a calculation dependent on the ascent rate which was traditionally taken to be constant. This study presents a new thermodynamic model which allows us to compute the thermal jump between the surrounding environment and the lifting gas as a function of different parameters such as the atmospheric temperature lapse rate or the physical characteristics of the balloon. The size of the thermal jump and its effect on the ascent rate is discussed for a 30 g pilot balloon, which was the type used at the Ebro Observatory (EO) between 1952 and 1963. The meridional and zonal components of the wind profile from ground level up to 10 km altitude were computed by applying the model using EO digitized data for a sample of this period. The obtained results correlate very well with those obtained from the ERA5 reanalysis. A very small thermal jump with a weak effect on the computed ascent rate was found. This ascent rate is consistent with the values assigned in that period to the balloons filled with hydrogen used at the Ebro Observatory and to the 30 g balloons filled with helium used by the US National Weather Service.

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