Effects of Multiblocking and Axial Gap Distance on Performance of Partial Admission Turbines: A Numerical Analysis

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Narmin Baagherzadeh Hushmandi ◽  
Torsten H. Fransson
Keyword(s):  
Rotor Blades ◽  
Test Case ◽  
Two Stage ◽  
Second Stage ◽  
Partial Admission ◽  
Flow Interactions ◽  
Single Arc ◽  
And Performance ◽  
Stage Efficiency ◽  
Better Than

In this paper, the effects of axial gap distance between the first stage stator and rotor blades and multiblocking on aerodynamics and performance of partial admission turbines are analyzed numerically. The selected test case is a two stage axial steam turbine with low reaction blades operating with compressed air. The multiblocking effect is studied by blocking the inlet annulus of the turbine in a single arc and in two opposing blocked arcs, each having the same admission degree. The effect of axial gap distance between the first stage stator and rotor blades is studied while varying the axial gap by 20% compared with the design gap distance. Finally, full admission turbine is modeled numerically for comparison. Performance of various computational cases showed that the first stage efficiency of the two stage partial admission turbine with double blockage was better than that of the single blockage turbine; however, the extra mixing losses of the double blockage turbine caused the efficiency to deteriorate in the downstream stage. It was shown that the two stage partial admission turbine with smaller axial gap than the design value had better efficiency of the first stage due to lower main flow and leakage flow interactions; however, the efficiency at the second stage decreased faster compared with the other cases. Numerical computations showed that the parameters, which increased the axial force of the first stage rotor wheel for the partial admission turbine, were longer blocked arc, single blocked arc, and reduced axial gap distance between the first stage stator and rotor blades.

An Enhanced Two Stage MMSE Equalizer for Coded FBMC/OQAM Systems

2019 ◽  
Vol 10 (1) ◽  
pp. 69-82 ◽  
Author(s):  
Mohammad Rizk Assaf ◽  
Abdel-Nasser Assimi
Keyword(s):  
Error Propagation ◽  
Channel Model ◽  
Error Correcting Codes ◽  
Two Stage ◽  
Probability Of Error ◽  
Second Stage ◽  
Different Types ◽  
Mmse Equalizer ◽  
And Performance ◽  
Ici Cancellation

In this article, the authors investigate the enhanced two stage MMSE (TS-MMSE) equalizer in bit-interleaved coded FBMC/OQAM system which gives a tradeoff between complexity and performance, since error correcting codes limits error propagation, so this allows the equalizer to remove not only ICI but also ISI in the second stage. The proposed equalizer has shown less design complexity compared to the other MMSE equalizers. The obtained results show that the probability of error is improved where SNR gain reaches 2 dB measured at BER compared with ICI cancellation for different types of modulation schemes and ITU Vehicular B channel model. Some simulation results are provided to illustrate the effectiveness of the proposed equalizer.

scholarly journals Comparison of estimators in one-phase two-stage Poisson sampling in forest inventories

2012 ◽  
Vol 42 (10) ◽  
pp. 1865-1871 ◽  
Author(s):  
Daniel Mandallaz ◽  
Alexander Massey
Keyword(s):  
Small Area ◽  
Two Stage ◽  
Random Sample Size ◽  
Poisson Sampling ◽  
Second Stage ◽  
Forest Inventories ◽  
Unbiased Estimates ◽  
The Mean ◽  
Concentric Circles ◽  
Better Than

In the context of Poisson sampling, numerous adjustments to classical estimators have been proposed that are intended to compensate for inflated variance due to random sample size. However, such adjustments have never been applied to extensive forest inventories. This work investigates the performances of four estimators for the timber volume in one-phase two-stage forest inventories, where trees in the first stage are selected, at the plot level, by concentric circles or angle-count methods and a subset thereof are selected by Poisson sampling for further measurements to get a better estimation. The original two-stage estimator is the sum of two components: the first is the mean of Horwitz–Thompson estimators using simple volume approximations, based on diameter and species alone, of all first-stage trees in each inventory plot, and the second is the mean of Horwitz–Thompson estimators based on the differences between the simple volume approximations and refined volume determinations based on further diameter and height measurements on the second-stage trees within each inventory plot. This two-stage estimator is particularly useful because it provides unbiased estimates even if the simple prediction model is not correct, which is particularly important for small area estimation. The other three estimators rely on adjustments of the second component of the original estimator that are adapted from estimators proposed in the literature by L.R. Grosenbaugh and C.-E. Särndal. It turns out that these adjustments introduce a negligible bias and that the original simple estimator performs just as well or even better than the new estimators with respect to the variance.

scholarly journals Design and Analysis of a Split Deswirl Vane in a Two-Stage Refrigeration Centrifugal Compressor

2014 ◽  
Vol 6 ◽  
pp. 130925 ◽  
Author(s):  
Jeng-Min Huang ◽  
Yue-Hann Tsai
Keyword(s):  
Centrifugal Compressor ◽  
Rotation Angle ◽  
Guide Vane ◽  
Low Flow ◽  
Working Fluid ◽  
Inlet Guide Vane ◽  
Two Stage ◽  
Double Row ◽  
Second Stage ◽  
Better Than

This study numerically investigated the influence of using the second row of a double-row deswirl vane as the inlet guide vane of the second stage on the performance of the first stage in a two-stage refrigeration centrifugal compressor. The working fluid was R134a, and the turbulence model was the Spalart-Allmaras model. The parameters discussed included the cutting position of the deswirl vane, the staggered angle of two rows of vane, and the rotation angle of the second row. The results showed that the performance of staggered angle 7.5° was better than that of 15° or 22.5°. When the staggered angle was 7.5°, the performance of cutting at 1/3 and 1/2 of the original deswirl vane length was slightly different from that of the original vane but obviously better than that of cutting at 2/3. When the staggered angle was 15°, the cutting position influenced the performance slightly. At a low flow rate prone to surge, when the second row at a staggered angle 7.5° cutting at the half of vane rotated 10°, the efficiency was reduced by only about 0.6%, and 10% of the swirl remained as the preswirl of the second stage, which is generally better than other designs.

scholarly journals Research on Efficiency of Animation Enterprises Based on Two-Stage DEA Network System Model of Sharing Input Resources

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Shuo Zhang ◽  
Xuemei Yang ◽  
Jian Zhang ◽  
Mengjie Liao ◽  
Lin Qi
Keyword(s):  
Production Quality ◽  
System Model ◽  
Network System ◽  
Research Model ◽  
Two Stage ◽  
Second Stage ◽  
Production Quantity ◽  
Overall Efficiency ◽  
Stage Efficiency

This research constructs a two-stage DEA network system model of shared input resources to evaluate the efficiency of animation companies: the first-stage efficiency to reflect the production quantity and the second-stage efficiency to reflect the production quality of animation products, where the quality of animation products is judged based on the market recognition of the animation products. The overall efficiency in the research model is used to describe the development of animation enterprises. According to the result, it is concluded that the overall efficiency of the surveyed animation companies and the efficiency of each sub-stage have shown an upward trend, which is in line with the growth of the company's development.

scholarly journals The effect of the Zahoric model in learning some kinetic sentences

2020 ◽  
Vol 19 (2) ◽  
pp. 0045
Author(s):  
M. Maison Mohammed Dr. Luma Sameer
Keyword(s):  
Teaching Method ◽  
Control Group ◽  
Second Stage ◽  
Short Period ◽  
Post Test ◽  
And Performance ◽  
And Control ◽  
Experimental Group ◽  
Positive Results ◽  
Better Than

When teaching or training fencing we find that most learners are able to perform some fencing skills during learning within the lesson, but they find it difficult to perform the same skills when linked in one sentence after a short period or in subsequent lessons, or during practical exams, so I conducted those Study to develop solutions to this problem by investing the Zahoric model and its distinctive educational steps in learning the kinetic sentences in the female blinds, and its impact on the process of learning and linking kinetic sentences in the sport of fencing and make the learning process more effective and economical.   The experimental method was used by designing the experimental and control groups with pre- and post-test on a sample of the second stage students (B22), representing the experimental group and learning the skills using the Zahoric model in its five steps, while the (D26) student representing the control group, which is learning the fencing skills according to the teaching method. Followed. The learning and performance of some kinetic sentences were evaluated by a standardized form of fencing according to the parts of the movement and their manifestations.  An educational curriculum has been prepared using the Zahorik model to learn the kinetic sentences by fencing according to the sectoral vocabulary of the second semester by following the steps of the model (activating information - acquiring - understanding - using - thinking in information). After the statistical treatments, it was concluded that the Zoharic model, designed to learn some kinetic sentences in the experimental group, gave positive results in evaluating the kinetic sentences better than the teaching method used in the control group. In light of the conclusion, it is recommended to adopt the Zoharik model in learning some kinetic sentences with a blind weapon, as it gives the learner a positive in the analysis, composition and understanding of the movements that are combined to give a kinetic sentence that ends with a touch in favor of the attacker who clearly understands where it begins and ends the syntax of the correct kinetic sentence, which resolves the sentence in his favor.

A model for the conservation of interactive electroacoustic repertoire: analysis, reconstruction, and performance in the face of technological obsolescence

2006 ◽  
Vol 11 (3) ◽  
pp. 273-284 ◽  
Author(s):  
DAVID BROOKE WETZEL
Keyword(s):  
Test Case ◽  
Test Cases ◽  
Interactive Electronics ◽  
Second Stage ◽  
Third Stage ◽  
Specific Device ◽  
The Face ◽  
Available Technology ◽  
And Performance ◽  
Stage Analysis

This paper presents a three-stage model (analysis, reconstruction and performance) for the conservation of interactive electroacoustic works for which the original technology is now obsolete or otherwise unavailable. The first stage, analysis, is a detailed documentation of the electronic processes and effects required for each work in a format that is independent of any specific device or system. The analysis provides a blueprint for future realisations using available technology. The second stage, reconstruction, provides a working performance resource, as well as a test case for the validity of the analysis. Reconstructed systems are then tested and refined through the third stage, performance. With repeated performances, compositions gain wider exposure and may be evaluated by listeners on their musical merits. To date, the author has analysed, reconstructed and performed several works for clarinet and interactive electronics. Each performance has informed the continued development of the newly reconstructed system, and has in some cases led to corrections to the underlying analysis. As a classically trained clarinettist and computer musician, the author's approach to the conservation of electroacoustic repertoire comes from a desire to find performable works and to keep them viable and accessible for as long as possible. Four works for clarinet and interactive electronics (by Musgrave, Pennycook, Kramer, and Lippe) are presented as test cases for this model.

Wastewater Minimisation Using a Heuristic Procedure

2004 ◽  
Vol 2 (1) ◽  
Author(s):  
Zhi-Yong Liu ◽  
Zisheng Jason Zhang ◽  
Linna Hu ◽  
Zhaoliang Wu
Keyword(s):  
Mass Balance ◽  
Heuristic Procedure ◽  
Heuristic Rules ◽  
Two Stage ◽  
Flow Rates ◽  
Second Stage ◽  
Better Than

A two-stage procedure is proposed for the minimisation of wastewater. In the first stage, heuristic rules are used to find the initial feasible flowsheet; in the second stage, the flow rates of streams in the initial flowsheet are determined by mass balance of the contaminants. The operations considered in this work include re-use, regeneration, mixing and bypassing of water streams. The proposed procedure is simple and the results of the examples studied are comparable with or better than those found in the literature.

Dynamic Modelling and Performance of a Two Stage Piezoelectric Servovalve

2016 ◽  
Author(s):  
Johan Persson ◽  
Andrew R. Plummer ◽  
Christopher R. Bowen ◽  
Phil L. Elliott
Keyword(s):  
Closed Loop ◽  
Dynamic Modelling ◽  
Flow Characteristics ◽  
The Other ◽  
Step Response ◽  
Hydraulic Fluid ◽  
Two Stage ◽  
Second Stage ◽  
And Performance ◽  
Spool Valve

This paper describes the design, simulation and testing of a piezoelectrically-actuated two stage spool valve. The first stage is a small spool controlled by a piezoelectric ring bender and the second stage is a closed loop position controlled main spool. A dynamic mathematical model of the valve has been derived. Step response tests for both the first stage and second stage are presented, and experimental second stage frequency response results are shown. The mathematical models for the amplifier, first stage and second stage spool behaviour are validated against experimental data. The second stage spool behaviour is found to be very sensitive to the first stage flow characteristics. In addition, the displacement of the hydraulic fluid by the piezoelectric ring bender, from one side of the piezoelectric ring bender to the other, had a significant impact on the valve characteristics.

TWO-STAGE EFFICIENCY MEASUREMENT AND TECHNOLOGICAL HETEROGENEITY: EVIDENCE FROM THE BIOTECHNOLOGICAL INDUSTRY IN TAIWAN

2014 ◽  
Vol 31 (01) ◽  
pp. 1450007
Author(s):  
YUNG-HSIANG LU ◽  
YUNG-HO CHIU ◽  
CHING-REN CHIU ◽  
YU-CHIAO HUNG
Keyword(s):  
Time Lag ◽  
Listed Companies ◽  
Two Stage ◽  
Listed Firms ◽  
Second Stage ◽  
Business Operations ◽  
Efficiency Assessment ◽  
Operating Process ◽  
Gap Ratio ◽  
Stage Efficiency

This paper explores the operational and market efficiencies of various biotechnological company formats in Taiwan during the period 2006 to 2008 by adopting the two-stage directional distance function and the meta-frontier concept. It conducts an efficiency assessment by taking into account a five-year time lag between R&D investments and actually obtaining a patent in order to better reflect the actual business operating process and thus more accurately gauge the efficiency of business operations in biotechnological companies. The empirical results show that non-listed companies registered better operational efficiency in the first stage, whereas their market efficiency in the second stage is inferior to that of listed companies when the meta-technology set is used as a basis. The average operation gap ratio and market gap ratio of non-listed companies exceeded those of listed firms, indicating that the technological heterogeneity (i.e., the gap) of non-listed companies is smaller than that of listed ones.

Treatment of Leachate by Aged-Refuse Reactor in Natural Ventilation during Autumn and Winter

2011 ◽  
Vol 374-377 ◽  
pp. 821-825
Author(s):  
Jie Yu Luo ◽  
Xiao Jie Sun ◽  
Dun Qiu Wang ◽  
Yi Nian Zhu
Keyword(s):  
Natural Ventilation ◽  
Removal Rate ◽  
Effect Of Temperature ◽  
Two Stage ◽  
Second Stage ◽  
Treated Effluent ◽  
Aged Refuse ◽  
Cod Removal Rate ◽  
Autumn And Winter ◽  
Better Than

The effect of temperature on two stage aged-refuse-based reactor which treats leachate in natural ventilation was investigated in autumn and winter. Results indicate that the average concentrations of COD in treated effluent increase from 726 mg/L in autumn to 2000 mg/L in winter in the first stage reactor while they are 246 mg/L and 1010 mg/L respectively in the second stage reactor. The average concentrations of NH3-N in treated effluent increase from 123.7 mg/L in autumn to 620 mg/L in winter in the first stage reactor while they are 123.7 mg/L and 620 mg/L respectively in the second stage reactor. Accordingly, the average removal rates of COD decrease from 81.7% of autumn to 73% of winter in the first stage reactor and decrease from 64.7% to 52% in the second stage reactor, and finally, the total COD removal rate in this system drops from 92.7% in autumn to 85.8% in winter. So we can conclude that the effect of temperature on the first stage aged refuse reactor is better than that on the second stage aged refuse reactor.

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