scholarly journals Measurements of Discharge through a Pump-Turbine in Both Flow Directions Using Volumetric Gauging and Pressure-Time Methods

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4706
Author(s):  
Adam Adamkowski ◽  
Waldemar Janicki ◽  
Mariusz Lewandowski
Keyword(s):  
Operation Mode ◽  
Detailed Comparison ◽  
Pump Operation ◽  
Special Procedure ◽  
Pressure Time ◽  
Mode Of Operation ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Directions ◽  
The Impact ◽  
Low Uncertainty

This article presents the original procedures for measuring the flow rate using the pressure-time and the volumetric gauging method in the case of performance tests of a reversible hydraulic machine in either turbine or pump modes of operation. Achieving the lowest possible measurement uncertainty was one of the basic conditions during implemented machine tests. It was met using appropriate measuring procedures and high-class measuring equipment. Estimation of the uncertainty for both methods was made on the basis of an analysis consistent with current requirements in this respect. The pressure-time method was supplemented by the computational fluid dynamics (CFD) analysis that allowed reducing the impact of the pipeline complex irregular geometry on the uncertainty of flow measurement. Appropriate modifications of the calculation procedure enabled accurate measurements of flow during the pump mode of operation of the tested machine as well. The volumetric gauging method, thanks to a special procedure used for accurate measurement of the water level in the upper reservoir of the power plant, allowed measuring the discharge through the tested reversible machine with very low uncertainty. The obtained results allowed for a detailed comparison and mutual verification of the methods used to measure the discharge of the tested reversible machine in both modes of its operation. The most possible causes of obtained results are discussed and summarized in the paper. The need for further research was pointed out to explain the differences obtained and their influence on the accuracy of discharge measurement using the pressure-time method in pump operation mode.

scholarly journals Partial integration of ADM1 into CFD: understanding the impact of diffusion on anaerobic digestion mixing

2020 ◽  
Vol 81 (8) ◽  
pp. 1658-1667 ◽  
Author(s):  
Yohannis Mitiku Tobo ◽  
Usman Rehman ◽  
Jan Bartacek ◽  
Ingmar Nopens
Keyword(s):  
Anaerobic Digestion ◽  
Homogeneous Distribution ◽  
Cfd Model ◽  
Homogeneity Analysis ◽  
Cfd Models ◽  
Mode Of Operation ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact ◽  
Proper Performance ◽  
Partial Integration

Abstract Sufficient mixing is crucial for the proper performance of anaerobic digestion (AD), creating a homogeneous distribution of soluble substrates, biomass, pH, and temperature. The opaqueness of the sludge and mode of operation make it challenging to study AD mixing experimentally. Therefore, hydrodynamics modelling employing computational fluid dynamics (CFD) is often used to investigate this mixing. However, CFD models mostly do not include biochemical reactions and, hence, ignore the effect of diffusion-induced transport on AD heterogeneity. The novelty of this work is the partial integration of Anaerobic Digestion Model no. 1 (ADM1) into the CFD model. The aim is to better understand the effect of advection–diffusion transport on the homogenization of soluble substrates and biomass. Furthermore, AD homogeneity analysis in terms of concentration distribution is proposed rather than the traditional velocity distributions. The computed results indicate that including diffusion-induced transport affects the homogeneity of AD.

Kombinasi Mode Cipher Block Chaining Dengan Algoritma Triangle Chain Cipher Pada Penyandian Login Website

2018 ◽  
Vol 2 (1) ◽  
pp. 1
Author(s):  
Dafirius Lombu ◽  
Siska Dame Tarihoran ◽  
Irwan Gulo
Keyword(s):  
Operation Mode ◽  
Feedback Mechanism ◽  
Database Access ◽  
Original Meaning ◽  
Mode Of Operation ◽  
Encryption And Decryption ◽  
Cryptographic Algorithms ◽  
Block Chaining

Generally, the database access of a website lies in the user login. When the login data is not accompanied by security techniques, it is very easily accessible by other parties. One effort that can be done to solve the problem is to encode the login data of website users based on cryptographic technique algorithm. Triangle Chain Cipher (TCC) is one of the classic cryptographic algorithms that encode data doubly and generate keys randomly along the plain. The process of encryption and decryption are interdependent to be one of the advantages of this algorithm. This algorithm will be more effective when combined with the Cipher Block Chaining (CBC) operation mode that is widely used in modern cryptographic algorithms today. The feedback mechanism between the blocks in this mode of operation is the operating advantage. This study describes how to combine the mode of operation of block chaining cipher with triangle chain cipher algorithm so that cipher data login website generated more random and difficult to find its original meaning.

scholarly journals The Impact of Participation in PPP Projects on Total Factor Productivity of Listed Companies in China

2021 ◽  
Vol 13 (14) ◽  
pp. 7603
Author(s):  
Xiangdong Liu ◽  
Guangxi Cao
Keyword(s):  
Total Factor Productivity ◽  
High Speed ◽  
Operation Mode ◽  
Listed Companies ◽  
Financing Constraints ◽  
Eastern Region ◽  
Time Varying ◽  
Factor Productivity ◽  
The Impact ◽  
China’S Economy

The key to transforming China’s economy from high-speed growth to high-quality development is to improve total factor productivity (TFP). Based on the panel data of China’s listed companies participating in PPP (Public–Private Partnerships) projects from 2010 to 2019, this paper constructs the time-varying DID method to test the impact of participation in PPP projects on the company’s TFP empirically, explore the mechanism of the effect of participation in PPP projects on the company’s TFP, and then conduct heterogeneous analysis from four perspectives: region, industry, ownership form, and operation mode. The empirical results show that participation in PPP projects can significantly promote the growth of the company’s TFP, which mainly comes from the promotion of the innovation level of listed companies and the alleviation of financing constraints by participating in PPP projects. In addition, participation in PPP projects has a significant impact on TFP of listed companies in the eastern region, listed companies in the secondary and tertiary industries, state-owned listed companies, and listed companies participating in PPP projects under the BOT mode.

scholarly journals GNSS-to-GNSS time offsets: study on the broadcast of a common reference time

GPS Solutions ◽  
2021 ◽  
Vol 25 (2) ◽  
Author(s):  
Ilaria Sesia ◽  
Giovanna Signorile ◽  
Tung Thanh Thai ◽  
Pascale Defraigne ◽  
Patrizia Tavella
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Reference Time ◽  
Single Time ◽  
Common Reference ◽  
Prediction Quality ◽  
Common Time ◽  
Time Offset ◽  
The Impact ◽  
Low Uncertainty

AbstractWe present two different approaches to broadcasting information to retrieve the GNSS-to-GNSS time offsets needed by users of multi-GNSS signals. Both approaches rely on the broadcast of a single time offset of each GNSS time versus one common time scale instead of broadcasting the time offsets between each of the constellation pairs. The first common time scale is the average of the GNSS time scales, and the second time scale is the prediction of UTC already broadcast by the different systems. We show that the average GNSS time scale allows the estimation of the GNSS-to-GNSS time offset at the user level with the very low uncertainty of a few nanoseconds when the receivers at both the provider and user levels are fully calibrated. The use of broadcast UTC prediction as a common time scale has a slightly larger uncertainty, which depends on the broadcast UTC prediction quality, which could be improved in the future. This study focuses on the evaluation of two different common time scales, not considering the impact of receiver calibration, at the user and provider levels, which can nevertheless have an important impact on GNSS-to-GNSS time offset estimation.

The Journalist—Source Relationship in Context: A Comparative Review of US and English Law

2009 ◽  
Vol 38 (3) ◽  
pp. 268-294
Author(s):  
Stuart Wallace
Keyword(s):  
Human Rights ◽  
Legal Protection ◽  
State Level ◽  
Potential Threat ◽  
Shield Law ◽  
Special Procedure ◽  
European Court ◽  
Comparative Review ◽  
The Uk ◽  
The Impact

This paper analyses the legal protection of the journalist–source relationship from both sides and the underlying interests involved. The paper begins by analysing why the relationship deserves protection. The position of journalists at common law is analysed with a discussion of the application of the principle established in Norwich Pharmacal v Customs and Excise to journalists. The development of immunity from contempt in s. 10 of the Contempt of Court Act 1981 is examined to illustrate the ideological clash between the judiciary and journalists. The impact of the Human Rights Act and decisions of the European Court of Human Rights are analysed to assess whether this will lead to a change in attitudes in the UK. Finally, the potential threat to journalists posed by compelled evidentiary disclosure in criminal cases is reviewed, with a particular look at ‘special procedure’ material. The US section begins with an analysis of the law at federal level, the decisions of the Supreme Court, including the leading decision of Branzburg v Hayes, as well as the role the legislature has played. The paper then analyses protections provided at state level, with a case study of the California shield law and a review of Californian jurisprudence.

scholarly journals Greater fit and a greater gap

2019 ◽  
Vol 26 (4) ◽  
pp. 561-594
Author(s):  
Steven A. Brieger ◽  
Dirk De Clercq ◽  
Jolanda Hessels ◽  
Christian Pfeifer
Keyword(s):  
Life Satisfaction ◽  
Institutional Environment ◽  
Entrepreneurial Activity ◽  
Worker Rights ◽  
Content Type ◽  
Person Environment Fit ◽  
High Power Distance ◽  
High Degree ◽  
The Impact ◽  
Low Uncertainty

Purpose The purpose of this paper is to understand how national institutional environments contribute to differences in life satisfaction between entrepreneurs and employees. Design/methodology/approach Leveraging person–environment fit and institutional theories and using a sample of more than 70,000 entrepreneurs and employees from 43 countries, the study investigates how the impact of entrepreneurial activity on life satisfaction differs in various environmental contexts. An entrepreneur’s life satisfaction arguably should increase when a high degree of compatibility or fit exists between his or her choice to be an entrepreneur and the informal and formal institutional environment. Findings The study finds that differences in life satisfaction between entrepreneurs and employees are larger in countries with high power distance, low uncertainty avoidance, extant entrepreneurship policies, low commercial profit taxes and low worker rights. Originality/value This study sheds new light on how entrepreneurial activity affects life satisfaction, contingent on the informal and formal institutions in a country that support entrepreneurship by its residents.

Assessment of Unsteady Flows in Turbines

1992 ◽  
Vol 114 (1) ◽  
pp. 79-90 ◽  
Author(s):  
O. P. Sharma ◽  
G. F. Pickett ◽  
R. H. Ni
Keyword(s):  
Unsteady Flow ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Experimental Investigations ◽  
Flow Parameters ◽  
Research Activities ◽  
Flow Features ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Design ◽  
The Impact

The impacts of unsteady flow research activities on flow simulation methods used in the turbine design process are assessed. Results from experimental investigations that identify the impact of periodic unsteadiness on the time-averaged flows in turbines and results from numerical simulations obtained by using three-dimensional unsteady Computational Fluid Dynamics (CFD) codes indicate that some of the unsteady flow features can be fairly accurately predicted. Flow parameters that can be modeled with existing steady CFD codes are distinguished from those that require unsteady codes.

Sail Aero-Structures: Studying Primary Load Paths and Distortion

2005 ◽  
Author(s):  
Robert Ranzenbach ◽  
Zhenlong Xu
Keyword(s):  
Aerodynamic Load ◽  
Element Analysis ◽  
Strain Behavior ◽  
Construction Methods ◽  
Load Paths ◽  
Calculation Results ◽  
Computational Fluid Dynamics Cfd ◽  
Aerodynamic Field ◽  
The Impact ◽  
Primary Load

A method is described to conduct an integrated Fluid-Structure Interaction (FSI) simulation of sails that is based upon knowledge of the sail’s design shape geometry and membrane material properties. A Finite Element Analysis (FEA) of the sail structure and a Computational Fluid Dynamics (CFD) model of the aerodynamic field are combined and iteratively solved to compute the actual flying shape of the sail under aerodynamic load, the stress strain behavior of the sail membrane, the integrated aerodynamic forces produced by the sail such as driving force and heel moment, and the resulting loads on sheets, halyards, etc. An important contribution of this particular method is the incorporation of wrinkling phenomena into the FEA portion of the calculation. Results from a study of working sails for a 30’ MORC racing yacht designed by Nelson-Marek (NM) in the 1990’s are presented and discussed with particular emphasis on the variability of primary load paths with changing trim and sailing conditions as well as the impact of sail deformation in the direction of relatively small stresses that is often poorly addressed in many proprietary sail construction methods.

Effect of Buoyancy and Density Ratio on Heat Transfer in a Smooth Cooling Channel of a Gas Turbine Blade

2018 ◽  
Author(s):  
Mandana S. Saravani ◽  
Saman Beyhaghi ◽  
Ryoichi S. Amano
Keyword(s):  
Heat Transfer ◽  
Rotational Speed ◽  
Cfd Simulation ◽  
Density Ratio ◽  
Reynolds Numbers ◽  
Buoyancy Effect ◽  
Square Channel ◽  
First Case ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

The present work investigates the effects of buoyancy and density ratio on the thermal performance of a rotating two-pass square channel. The U-bend configuration with smooth walls is selected for this study. The channel has a square cross-section with a hydraulic diameter of 5.08 cm (2 inches). The lengths of the first and second passes are 514 mm and 460 mm, respectively. The turbulent flow enters the channel with Reynolds numbers of up to 34,000. The rotational speed varies from 0 to 600 rpm with the rotational numbers up to 0.75. For this study, two approaches are considered for tracking the buoyancy effect on heat transfer. In the first case, the density ratio is set constant, and the rotational speed is varied. In the second case, the density ratio is changed in the stationary case, and the effect of density ratio is discussed. The range of Buoyancy number along the channel is 0–6. The objective is to investigate the impact of Buoyancy forces on a broader range of rotation number (0–0.75) and Buoyancy number scales (0–6), and their combined effects on heat transfer coefficient for a channel with aspect ratio of 1:1. Several computational fluid dynamics (CFD) simulation are carried out for this study, and some of the results are validated against experimental data.

Impact of Severe Temperature Distortion on Turbine Efficiency

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Paul F. Beard ◽  
Andy Smith ◽  
Thomas Povey
Keyword(s):  
Computational Study ◽  
Measurement Techniques ◽  
Inlet Temperature ◽  
Turbine Efficiency ◽  
Computational Fluid Dynamics Cfd ◽  
External Flows ◽  
Torque Transducer ◽  
Formed Part ◽  
Low Uncertainty ◽  
The Eu

This paper presents an experimental and computational study of the effect of severe inlet temperature distortion (hot streaks) on the efficiency of the MT1 HP turbine, which is a highly-loaded unshrouded transonic design. The experiments were performed in the Oxford Turbine Research Facility (OTRF) (formerly the TTF at QinetiQ Farnborough): an engine scale, short duration, rotating transonic facility, in which M, Re, Tgas/Twall and N/T01 are matched to engine conditions. The research formed part of the EU Turbine Aero-Thermal External Flows (TATEF II) program. An advanced second generation temperature distortion simulator was developed for this investigation, which allows both radial and circumferential temperature profiles to be simulated. A pronounced profile was used for this study. The system was novel in that it was designed to be compatible with an efficiency measurement system which was also developed for this study. To achieve low uncertainty (bias and precision errors of approximately 1.5% and 0.2% respectively, to 95% confidence), the mass flow rate of the hot and cold streams used to simulate temperature distortion were independently metered upstream of the turbine nozzle using traceable measurement techniques. Turbine power was measured directly with an accurate torque transducer. The efficiency of the test turbine was evaluated experimentally for a uniform inlet temperature condition, and with pronounced temperature distortion. Mechanisms for observed changes in the turbine exit flow field and efficiency are discussed. The data are compared in terms of flow structure to full stage computational fluid dynamics (CFD) performed using the Rolls Royce Hydra code.

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