Assessment of the Computing Time for the IAPWS-IF97 Equations

2006 ◽  
Vol 129 (3) ◽  
pp. 885-887 ◽  
Author(s):  
Kiyoshi Miyagawa
Keyword(s):  
Thermodynamic Properties ◽  
Simple Structure ◽  
Computer Systems ◽  
Computing Time ◽  
Ordinary Water ◽  
Independent Variables ◽  
Modern Computer ◽  
Water Substance

Computing times of equations based on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (IAPWS-IF97) were tested. Modern computer systems are optimized for “simple” computational operations, which favors the simple structure of IAPWS-IF97. Provision of “backward equations,” which are approximation of inverse equations, is one of the features of IAPWS-IF97. The backward equations showed much shorter computing times than iterative routines, which had been used to calculate with several independent variables. IAPWS-IF97 is faster than the equations of IAPWS Formulation 1995 for the Thermodynamic properties of Ordinary Water Substance for General and Scientific Use (IAPWS-95) by factors 70 to 200 times.

An Equation of State for Compressed Water from 1 to 1000 Bar and from 0°C tO 150°C

1968 ◽  
Vol 10 (4) ◽  
pp. 319-328 ◽  
Author(s):  
M. R. Gibson ◽  
E. A. Bruges
Keyword(s):  
Equation Of State ◽  
Thermodynamic Properties ◽  
Equations Of State ◽  
Dynamic Properties ◽  
Similar Type ◽  
Independent Variables ◽  
Turbine Performance ◽  
Dependent Variables ◽  
Water Turbine ◽  
Water Substance

The precision with which the thermodynamic properties of compressed water and steam are known has led, not unnaturally, to the development of equations of state suitable only for use on electronic digital computers. The equations are in the main empirical although some are highly sophisticated and lead to lengthy programs and complex sub-routines. Among such equations are those of the 1966 and 1967 Formulations of the Thermo-dynamic Properties of Ordinary Water Substance prepared by the International Formulation Committee of the International Steam Conference. The favoured form of equation has been one in which the dependent variables are enthalpy, volume and entropy and the independent variables pressure and temperature. However, this form of equation may not prove to be always the most suitable and the purpose of this paper is to describe how another type of equation, in which the dependent variable is enthalpy and the independent variables are pressure and entropy, may be established and applied. It is believed that this particular type of equation, relating as it does the three most important parameters in pump and turbine performance, has special qualities for design and efficiency calculations. By way of example the efficiency of a water turbine is evaluated according to the ‘thermodynamic method’ described by Thom (2). A concluding section outlines the further steps being taken by the authors to provide a similar type of equation over ranges of pressure and temperature up to 1000 bar and 1000°C.

Supplementary Backward Equations v(p,T) for the Critical and Supercritical Regions (Region 3) of the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
H.-J. Kretzschmar ◽  
A. H. Harvey ◽  
K. Knobloch ◽  
R. Mareš ◽  
K. Miyagawa ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Critical Point ◽  
International Association ◽  
Computing Time ◽  
Computer Time ◽  
Singular Behavior ◽  
Steam Power ◽  
Power Cycles ◽  
Independent Variables ◽  
Iterative Procedures

When steam power cycles are modeled, thermodynamic properties as functions of pressure and temperature are required in the critical and supercritical regions (region 3 of IAPWS-IF97). With IAPWS-IF97, such calculations require cumbersome iterative calculations, because temperature and volume are the independent variables in the formulation for this region. In order to reduce the computing time, the International Association for the Properties of Water and Steam (IAPWS) adopted a set of backward equations for volume as a function of pressure and temperature in region 3. The necessary numerical consistency is achieved by dividing the region into 20 subregions, plus auxiliary subregions near the critical point in which the consistency requirements are relaxed due to the singular behavior at the critical point. In this work, we provide complete documentation of these equations, along with a discussion of their numerical consistency and the savings in computer time. The numerical consistency of these equations should be sufficient for most applications in heat-cycle, boiler, and steam-turbine calculations; if even higher consistency is required, the equations may be used to generate guesses for iterative procedures.

New International Skeleton Tables for the Thermodynamic Properties of Ordinary Water Substance

1988 ◽  
Vol 17 (4) ◽  
pp. 1439-1540 ◽  
Author(s):  
H. Sato ◽  
M. Uematsu ◽  
K. Watanabe ◽  
A. Saul ◽  
W. Wagner
Keyword(s):  
Thermodynamic Properties ◽  
Ordinary Water ◽  
Water Substance

Cyber Threat Ransomware and Marketing to Networked Consumers

2020 ◽  
pp. 155-185
Author(s):  
Usman Javed Butt ◽  
Maysam F. Abbod ◽  
Arvind Kumar
Keyword(s):  
Critical Infrastructure ◽  
Computer Systems ◽  
Cyber Attacks ◽  
Competitive Market ◽  
Cyber Attack ◽  
Security Measures ◽  
Global Competitiveness ◽  
Modern Computer ◽  
Water Cleaning ◽  
Cyber Threat

Marketing is a process of creating, capturing, and exchanging ‘value' for the mutual benefits of marketers, customers, intermediaries, and other stakeholders. Such a transaction requires trust as it might be facing a range of online cyber risks. Modern cybercrimes have exponentially grown over the last decade. Ransomware is one of the types of malware which is the result of a sophisticated attempt to compromise the modern computer systems. The businesses, governments, and large corporations are investing heavily to combat this cyber threat against their critical infrastructure. New technological shifts help to improve marketing and business productivity and keep the company's global competitiveness in an overflowing competitive market. However, the businesses and the systems involved need security measures to protect integrity and availability which will help avoid any malfunctioning to their operations due to the cyber-attacks. There have been several cyber-attack incidents on several businesses such as healthcare, pharmaceutical, water cleaning, and energy sector.

Software Based Methods to Harden Embedded Software at Run-Time: A Survey

2015 ◽  
Author(s):  
Michael Kramer ◽  
Martin Horauer
Keyword(s):  
Embedded Systems ◽  
Computer Systems ◽  
Computer Software ◽  
Control Flow ◽  
Test Procedures ◽  
Modern Computer ◽  
Systems Software ◽  
Personal Computer Software ◽  
Control Flow Checking ◽  
Run Time

Embedded Systems software reliability is increasingly important, therefore methods to harden existing software are needed. In general, hardening software against various failures is a necessity in modern computer systems. A lot of work has been published regarding many possible ways to achieve this non-functional requirement. Relevant topics include, e.g., test procedures, recommended development flows, and hardware measures like watchdog timers. One of these methods seems very promising to be software implemented in modern embedded systems: Control Flow Checking by signatures. Various authors have shown the effectiveness and feasibility of Control Flow Checking (CFC) by signatures for personal computer software. For instance it has been shown for standard computer-systems, that CFC is capable of reducing undetected control flow errors by at least one magnitude. This survey will focus on the applicability of such software hardening methods to embedded systems, while adhering mainly to software based approaches. Published methods will be summarized and compared. Furthermore methods to simplify derived control-flow graphs to essential states will be emphasized. Finally the possibility to apply run-time verification to the Control-flow Checking Software is considered.

Properties of Ordinary Water-Substance in all its Phases

Nature ◽  
1940 ◽  
Vol 146 (3692) ◽  
pp. 145-146 ◽  
Author(s):  
N. K. ADAM
Keyword(s):  
Ordinary Water ◽  
Water Substance
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