Experimental Studies on the Design of Thermometer Pockets for Steam Mains

1973 ◽  
Vol 187 (1) ◽  
pp. 583-590
Author(s):  
J. E. Roughton
Keyword(s):  
Temperature Difference ◽  
Wall Temperature ◽  
Pipe Wall ◽  
Experimental Studies ◽  
Steam Temperature ◽  
Steam Pipe ◽  
Better Than ◽  
Good Agreement ◽  
Radiation Error ◽  
Conduction Error

The theory of thermometer pocket errors previously developed by the author has been tested by experiment using steam flows under steady-state conditions. When an appreciable temperature difference exists between steam and pipe wall, whatever the reason, errors arise from the temperature gradient in the steam and the loss of heat by conduction and radiation from the pocket. The results confirmed that the net error is a linear proportion of the steam/pipe wall temperature difference and can be substantial if the pocket is not of a suitable length. The effect of plating the pockets with rhodium was not as expected since the accompanying reduction in radiation error was offset by a larger increase in conduction error. In all other cases, the measured conduction plus radiation errors were in good agreement with the theory, while the effects of the steam temperature profile were also broadly as predicted. The basic theoretical approach was satisfactorily confirmed and the accuracy shown to be better than 5 per cent of the steam/pipe wall temperature difference.

Experimental Studies on the Design of Thermometer Pockets for Steam Mains

1973 ◽  
Vol 187 (1) ◽  
pp. 583-590
Author(s):  
J. E. Roughton
Keyword(s):  
Temperature Difference ◽  
Wall Temperature ◽  
Pipe Wall ◽  
Experimental Studies ◽  
Steam Temperature ◽  
Steam Pipe ◽  
Better Than ◽  
Good Agreement ◽  
Radiation Error ◽  
Conduction Error

The theory of thermometer pocket errors previously developed by the author has been tested by experiment using steam flows under steady-state conditions. When an appreciable temperature difference exists between steam and pipe wall, whatever the reason, errors arise from the temperature gradient in the steam and the loss of heat by conduction and radiation from the pocket. The results confirmed that the net error is a linear proportion of the steam/pipe wall temperature difference and can be substantial if the pocket is not of a suitable length. The effect of plating the pockets with rhodium was not as expected since the accompanying reduction in radiation error was offset by a larger increase in conduction error. In all other cases, the measured conduction plus radiation errors were in good agreement with the theory, while the effects of the steam temperature profile were also broadly as predicted. The basic theoretical approach was satisfactorily confirmed and the accuracy shown to be better than 5 per cent of the steam/pipe wall temperature difference.

Numerical Investigation of a Heated Sodium Jet in a Co-Flow

2007 ◽  
Author(s):  
I. Otic´ ◽  
A. G. Class
Keyword(s):  
Heat Transfer ◽  
Pipe Wall ◽  
Experimental Studies ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Mean Velocity ◽  
Temperature Variance ◽  
Physical Mechanisms ◽  
Insight Into ◽  
Good Agreement

Results of a numerical simulation of turbulent heated sodium jet in a co-flow using a combined LES-DNS approach are presented. The calculations correspond to the experiment of Knebel, Krebs, Muller and Axcell [1]. In agreement with the experimental results co-flow suppresses flow reversal along the outlet pipe wall. Comparisons of mean velocity, mean temperature, and temperature variance between experimental and numerical results show fairly good agreement. The results support the applicability of the combined LES-DNS approach for this type of flows. Simulations using this approach may complement experimental studies, allowing for better insight into the physical mechanisms of liquid metal turbulent heat transfer.

scholarly journals Experimental studies on the transformation from firn to ice in the wet-snow zone of temperate glaciers

1997 ◽  
Vol 24 ◽  
pp. 181-185 ◽  
Author(s):  
Katsuhisa Kawashima ◽  
Tomomi Yamada
Keyword(s):  
Experimental Studies ◽  
Ice Formation ◽  
Compression Tests ◽  
Densification Rate ◽  
Overburden Pressure ◽  
Proportionality Constant ◽  
Wet Snow ◽  
Water Saturated ◽  
The Relationship ◽  
Good Agreement

The densification of water-saturated firn, which had formed just above the firn-ice transition in the wet-snow zone of temperate glaciers, was investigated by compression tests under pressures ranging from 0.036 to 0.173 MPa, with special reference to the relationship between densification rate, time and pressure. At each test, the logarithm of the densification rate was proportional to the logarithm of the time, and its proportionality constant increased exponentially with increasing pressure. The time necessary for ice formation in the firn aquifer was calculated using the empirical formula obtained from the tests. Consequently, the necessary time decreased exponentially as the pressure increased, which shows that the transformation from firn in ice can be completed within the period when the firn aquifer exists, if the overburden pressure acting on the water-saturated firn is above 0.12–0.14 MPa. This critical value of pressure was in good agreement with the overburden pressure obtained from depth–density curves of temperate glaciers. It was concluded that the depth of firn–ice transition was self-balanced by the overburden pressure to result in the concentration between 20 and 30 m.

scholarly journals A balanced-to-balanced directional coupler based on branch-slotline coupled structure

Frequenz ◽  
2020 ◽  
Vol 74 (11-12) ◽  
pp. 427-433
Author(s):  
Yaxin Liu ◽  
Feng Wei ◽  
Xiaowei Shi ◽  
Cao Zeng
Keyword(s):  
Directional Coupler ◽  
Return Loss ◽  
Design Method ◽  
Differential Mode ◽  
Arbitrary Power ◽  
Measurement Results ◽  
Transition Structures ◽  
Coupled Structures ◽  
Better Than ◽  
Good Agreement

AbstractIn this paper, a balanced-to-balanced (BTB) branch-slotline directional coupler (DC) is firstly presented, which can realize an arbitrary power division ratios (PDRs). The coupler is composed by microstrip-to-slotline (MS) transition structures and branch-slotline coupled structures. The single-ended to balanced-ended conversion is simplified and easy to implemented by the MS transition structures, which intrinsically leads to the differential-mode (DM) transmission and common-mode (CM) suppression. Moreover, the different PDRs which are controlled by the widths of branch-slotlines can be achieved. In order to verify the feasibility of the proposed design method, two prototype circuits of the proposed coupler with different PDRs are fabricated and measured. The return loss and the isolation of two designs are all better than 10 dB. Moreover, the CM suppressions are greater than 35 dB. A good agreement between the simulation and measurement results is observed.

scholarly journals A high-fidelity realization of the Euclid code comparison N-body simulation with Abacus

2019 ◽  
Vol 485 (3) ◽  
pp. 3370-3377 ◽  
Author(s):  
Lehman H Garrison ◽  
Daniel J Eisenstein ◽  
Philip A Pinto
Keyword(s):  
Power Spectrum ◽  
High Performance ◽  
High Fidelity ◽  
Step Size ◽  
Time Step ◽  
Code Comparison ◽  
Force Accuracy ◽  
Integration Errors ◽  
Better Than ◽  
Good Agreement

Abstract We present a high-fidelity realization of the cosmological N-body simulation from the Schneider et al. code comparison project. The simulation was performed with our AbacusN-body code, which offers high-force accuracy, high performance, and minimal particle integration errors. The simulation consists of 20483 particles in a $500\ h^{-1}\, \mathrm{Mpc}$ box for a particle mass of $1.2\times 10^9\ h^{-1}\, \mathrm{M}_\odot$ with $10\ h^{-1}\, \mathrm{kpc}$ spline softening. Abacus executed 1052 global time-steps to z = 0 in 107 h on one dual-Xeon, dual-GPU node, for a mean rate of 23 million particles per second per step. We find Abacus is in good agreement with Ramses and Pkdgrav3 and less so with Gadget3. We validate our choice of time-step by halving the step size and find sub-percent differences in the power spectrum and 2PCF at nearly all measured scales, with ${\lt }0.3{{\ \rm per\ cent}}$ errors at $k\lt 10\ \mathrm{Mpc}^{-1}\, h$. On large scales, Abacus reproduces linear theory better than 0.01 per cent. Simulation snapshots are available at http://nbody.rc.fas.harvard.edu/public/S2016.

THEORETICAL CALCULATION OF pKb VALUES FOR ANILINES AND SULFONAMIDE DRUGS IN AQUEOUS SOLUTION

2012 ◽  
Vol 11 (02) ◽  
pp. 283-295 ◽  
Author(s):  
BAHRAM GHALAMI-CHOOBAR ◽  
ALI GHIAMI-SHOMAMI ◽  
PARIA NIKPARSA
Keyword(s):  
Gas Phase ◽  
Continuum Model ◽  
Correlation Equation ◽  
Polarizable Continuum Model ◽  
Free Energies ◽  
Pcm Model ◽  
Solvation Models ◽  
Polarizable Continuum ◽  
Better Than ◽  
Good Agreement

In this work, calculations of p K b values have been performed for aniline and its substituted derivatives and sulfonamide drugs by using Gaussian 98 software package. Gas-phase energies were calculated with HF /6-31 G ** and B3LYP /6-31 G ** levels of theory. Free energies of solvation have been computed using the polarizable continuum model (PCM), conductor-like polarizable continuum model (CPCM) and the integral equation formalism-polarizable continuum model (IEFPCM) at the same levels which have been used for geometry determination in the gas-phase. The results show that the calculated p K b values using the B3LYP /6-31 G ** are better than those using the corresponding HF /6-31 G **. At first, the correlation equation was found to determine the p K b values of the investigated anilines. Then, this correlation equation was used to calculate the p K b values of the sulfonamide drugs. The results obtained indicate that the PCM model is a suitable solvation model for calculating p K b values in comparison to the other solvation models. For the investigated compounds a good agreement between the experimental and the calculated p K b values was also observed.

FURTHER STUDIES ON NATURAL SELECTION AMONG HYBRIDS OF CARDUUS ACANTHOIDES AND CARDUUS NUTANS

1964 ◽  
Vol 42 (12) ◽  
pp. 1605-1613 ◽  
Author(s):  
R. J. Moore ◽  
G. A. Mulligan
Keyword(s):  
Natural Selection ◽  
Chromosome Number ◽  
Parental Species ◽  
Experimental Studies ◽  
Great Decrease ◽  
Carduus Acanthoides ◽  
Carduus Nutans ◽  
Experimental Plots ◽  
Better Than ◽  
Made In

A third 5-year survey made in 1962 of Carduus acanthoides, C. nutans, and their hybrids in Grey Co., Ontario, revealed that a great decrease in these populations had occurred. C. acanthoides and hybrids similar to this species had survived better than C. nutans but very little spread of either species seemed to have occurred in 1957–1962. In experimental plots the hybrid has been made and backcrossed to the parental species. The species differ in chromosome number (C. acanthoides, 2n = 22; C. nutans, 2n = 16) and hybrids have intermediate numbers. Evidence was found from field and experimental studies that the progeny of the F1 hybrid included a greater proportion of seedlings with the higher chromosome numbers than with the lower and intermediate numbers. It is suggested that this selection may operate through the rejection of the longer chromosomes received from C. nutans, which, in certain zygotic combinations may constitute an excess of chromatin lethal to the zygote.

Effect of Boundary Layer Suction on Aerodynamic Performance of High-Turning Compressor Cascade

2013 ◽  
Author(s):  
Longxin Zhang ◽  
Shaowen Chen ◽  
Hao Xu ◽  
Jun Ding ◽  
Songtao Wang
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Experimental Studies ◽  
Aerodynamic Performance ◽  
Parameter Distribution ◽  
Compressor Cascade ◽  
Boundary Layer Suction ◽  
End Wall ◽  
Low Speed Wind Tunnel ◽  
Good Agreement

Compared with suction slots, suction holes are (1) flexible in distribution; (2) alterable in size; (3) easy to fabricate and (4) high in strength. In this paper, the numerical and experimental studies for a high turning compressor cascade with suction air removed by using suction holes in the end-wall at a low Mach numbers are carried out. The main objective of the investigation is to study the influence of different suction distributions on the aerodynamic performance of the compressor cascade and to find a better compound suction scheme. A numerical model was first made and validated by comparing with the experimental results. The computed flow visualization and exit parameter distribution showed a good agreement with experimental data. Second, the model was then used to simulate the influence of different suction distributions on the aerodynamic performance of the compressor cascade. A better compound suction scheme was obtained by summarizing numerical results and tested in a low speed wind tunnel. As a result, the compound suction scheme can be used to significantly improve the performance of the compressor cascade because the corner separation gets further suppressed.

Analytical and Experimental Simulation of Loose Pedestal Dynamic Effects on a Rotating Machine Vibrational Response

1991 ◽  
Author(s):  
Pavel Goldman ◽  
Agnes Muszynska
Keyword(s):  
Excitation Frequency ◽  
Experimental Studies ◽  
Experimental Simulation ◽  
Physical Parameters ◽  
Vibrational Response ◽  
Rotating Machine ◽  
Qualitative Pattern ◽  
The Impact ◽  
Good Agreement ◽  
Periodic Changes

Abstract This report presents experimental, analytical, and numerical results describing vibrational phenomena in a rotating machine with one loose pedestal. The loose-pedestal machine rotor vibrations represent unbalance-related excited vibrations of synchronous and fractional subsynchronous regimes. In this study the loose-pedestal machine is first simulated by a simple vibrating beam excited by a shaker mounted on it. The shaker simulates an unbalanced machine rotor. The beam occasionally enters in contact with the foundation. The excited vibrations are modified by impacting occurrences, and by periodic changes in system stiffness. A new model of the impact has been developed. The results of analytical and experimental studies stand in a good agreement. They illustrate the existence of the synchronous regime and several subsynchronous fractional regimes in various excitation frequency ranges. The analysis adequately predicts the occurrence of these regimes and determines the physical parameters affecting them. The analytical and experimental results are then compared with the responses of experimental rotor rig with one bearing pedestal looseness. They show the same qualitative pattern.

Compact dual-mode microstrip bandpass filter based on slotted square patch resonator

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Karthie S. ◽  
Zuvairiya Parveen J. ◽  
Yogeshwari D. ◽  
Venkadeshwari E.
Keyword(s):  
Bandpass Filter ◽  
Filter Design ◽  
Center Frequency ◽  
Dual Mode ◽  
Content Type ◽  
Transmission Zeros ◽  
Compact Size ◽  
Mode Response ◽  
Better Than ◽  
Good Agreement

Purpose The purpose of this paper is to present the design of a compact microstrip bandpass filter (BPF) in dual-mode configuration loaded with cross-loop and square ring slots on a square patch resonator for C-band applications. Design/methodology/approach In the proposed design, the dual-mode response for the filter is realized with two transmission zeros (TZs) by the insertion of a perturbation element at the diagonal corner of the square patch resonator with orthogonal feed lines. Such TZs at the edges of the passband result in better selectivity for the proposed BPF. Moreover, the cross-loop and square ring slots are etched on a square patch resonator to obtain a miniaturized BPF. Findings The proposed dual-mode microstrip filter fabricated in RT/duroid 6010 substrate using PCB technology has a measured minimum insertion loss of 1.8 dB and return loss better than 24.5 dB with a fractional bandwidth (FBW) of 6.9%. A compact size of 7.35 × 7.35 mm2 is achieved for the slotted patch resonator-based dual-mode BPF at the center frequency of 4.76 GHz. As compared with the conventional square patch resonator, a size reduction of 61% is achieved with the proposed slotted design. The feasibility of the filter design is confirmed by the good agreement between the measured and simulated responses. The performance of the proposed filter structure is compared with other dual-mode filter works. Originality/value In the proposed work, a compact dual-mode BPF is reported with slotted structures. The conventional square patch resonator is deployed with cross-loop and square ring slots to design a dual-mode filter with a square perturbation element at its diagonal corner. The proposed filter exhibits compact size and favorable performance compared to other dual-mode filter works reported in literature. The aforementioned design of the dual-mode BPF at 4.76 GHz is suitable for applications in the lower part of the C-band.

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