Increasing Boiler Efficiencies

1975 ◽  
Author(s):  
R. P. O’Leary
Keyword(s):  
Difficult Problem ◽  
Definition Of

The most difficult problem in giving any talk, on any subject, is how to get started. I, myself, decided to go to Webster’s Dictionary to find the definition of efficiency. Webster defines it as follows: “Efficiency is the ratio of useful work obtained to energy expended”. I think it would be fair to say that the efficiency by which we convert energy to a saleable product will be the measure of a successful engineer. Paper published with permission.

Uncertainty Analysis in the Production History Matching by Using Proxies as Reservoir Simulators

2012 ◽  
Author(s):  
Paulo Camargo Silva ◽  
Virgílio José Martins Ferreira Filho
Keyword(s):  
Probability Density ◽  
Reservoir Simulation ◽  
History Matching ◽  
Simulation Models ◽  
Difficult Problem ◽  
Probability Density Functions ◽  
Density Functions ◽  
Production History ◽  
Definition Of ◽  
Reservoir Simulator

In the recent literature of the production history matching the problem of non-uniqueness of reservoir simulation models has been considered a difficult problem. Complex workflows have been proposed to solve the problem. However, the reduction of uncertainty can only be done with the definition of Probability Density Functions that are highly costly. In this article we introduce a methodology to reduce uncertainty in the history matching using techniques of Monte Carlo performed on proxies as Reservoir Simulator. This methodology is able to compare different Probability Density Functions for different reservoir simulation models to define among the models which simulation model can provide more appropriate matching.

An Elastic Theory for Rubber

1942 ◽  
Vol 15 (4) ◽  
pp. 790-797
Author(s):  
Elmer Latshaw
Keyword(s):  
Elastic Strain ◽  
Difficult Problem ◽  
Large Strains ◽  
Vulcanized Rubber ◽  
Working Stress ◽  
Real Value ◽  
Large Elastic Strain ◽  
Length Changes ◽  
Definition Of ◽  
Almost All

Abstract The elastic properties of vulcanized rubber present a difficult problem to generalize, mainly because of the large number of compounds in common use. There are good reasons for many kinds and grades, and a characteristic common to all is large elastic strain. Even in the best grades of rubber these strains are not perfectly elastic, but this is also true of almost all other materials, including spring steels. An elastic strain theory will be derived for a specific group of rubber compounds, namely, spring stocks. These are dense, strong rubbers, highly elastic within the working stress range, and capable of supporting loads under continuous vibration and shocks. To be of real value, the strain law should closely predict strain for the range of working stress, or more generally for the elastic range, and should indicate the trend at very high stresses where inelasticity becomes more prominent. Figure 1 shows a cylindrical element of rubber having an area A0 and length h when unstressed. If a uniform stress is imposed perpendicular to the end area, the length changes to H and the area to A. These symbols apply whether the stress is tension or compression. The usual definition of strain, i.e., change in length due to stress divided by the unstressed length, is comprehensive and descriptive for the large strains in rubber.

scholarly journals Synthesizing Normal and Non-Normal Modal Logics in Philosophical Epistemology Axiomatic System Modeled by the Logic Square and Hexagon of Opposition

2019 ◽  
pp. 894-907
Author(s):  
Vladimir O. Lobovikov
Keyword(s):  
Axiom System ◽  
Difficult Problem ◽  
Modal Logics ◽  
Axiomatic System ◽  
Border Line ◽  
History Of ◽  
The One ◽  
Definition Of ◽  
Axiomatic Systems ◽  
Normal Modal Logics

The paper aims at coping with the difficult problem of rationally uniting astonishingly huge amount of qualitatively different modal logics. For realizing this aim artificial languages of symbolic logic and the axiomatic methodology are used. Therefore, the method of constructing and studying formal logic inferences within the axiom system under investigation is exploited systematically. Inventing and elaborating a hitherto not-considered axiomatic system of epistemology uniting normal and not-normal modal logics is the new nontrivial scientific result of this work. History of philosophy and systematical philosophy, formal ethics and formal aesthetics, philosophical epistemology and analytical theology, philosophy of law and philosophy of science are among the important fields of application of the nontrivial abstract-theoretic principles demonstrated in this paper. Using the above-indicated machinery the author has arrived to the following main conclusion: the famous philosophical principles of utilitarianism, hedonism, optimism, pragmatism, fideism, falsifiability, verifiability, “Hume’s Guillotine”, “naturalistic fallacies” et al have not absolutely indefinite (unlimited) but quite definite (limited) sphere of relevant applicability; the precise formal definition of the border-line of mentioned sphere of relevance is the axiomatic one submitted and discussed in the paper. This general conclusion is instantiated in the text by several particular conclusions concerning explication and clarification of specific philosophical ideas and principles, for example, the one of kalokagathia. The author concludes that constructing and investigating the axiomatic systems of universal philosophical epistemology is indispensable for adequate representing human knowledge in artificial intellectual systems, for instance, in autonomous AI‑robots

The Treatment of Status Epilepticus

PEDIATRICS ◽  
1974 ◽  
Vol 53 (4) ◽  
pp. 536-540
Author(s):  
C. T. Lombroso
Keyword(s):  
Status Epilepticus ◽  
Serum Levels ◽  
Modern Medicine ◽  
Difficult Problem ◽  
Medical Emergency ◽  
Antiepileptic Medication ◽  
The Family ◽  
Convulsive Seizures ◽  
Definition Of ◽  
Tonic Phase

Status epilepticus, though declining in frequency in recent years, is a medical emergency as well as a persistently difficult problem in balanced therapy. By its very nature it is likely to require the direct involvement of the family physician be he a pediatrician or a general practitioner. It may be useful to begin by defining and considering special aspects in relation to causes and age. Most convulsive seizures are self-limiting events terminating on their own accord before specific medical treatment need or can be rendered. For these, positioning to prevent aspiration of excessive secretions and vomitus and prevention of self-injuries is generally sufficient. Prying open clenched teeth for the insertion of time-honored tongue blades, pencils, or fingers has no place in modern medicine. These maneuvers are useless in the prevention of tongue biting (that will have occurred at the onset of the initial tonic phase), but may actually be harmful by dislodging loose teeth, and by initiating nociceptive stimuli that reflexly can prolong the tonic phase. Likewise excessive restraining of convulsing patients may faciitate bone injuries. The administration of drugs postictally is unnecessary in the majority of isolated seizures. Exceptions of course are prolonged or serial convulsions, or status epilepticus as discussed below, and those instances in which the convulsion has occurred because of failure in taking prescribed antiepileptic medication. The recent availability for quick appraisal of serum levels of antiepileptic drugs is a useful guide in this respect. Turning now to the definition of status epilepticus: official formulations such as "an attack which is so prolonged or so frequently repeated as to constitute a definite lasting condition" is open to some confusion.

Primary Care Supplement

PEDIATRICS ◽  
1978 ◽  
Vol 61 (4) ◽  
pp. 671-672
Author(s):  
Frederick P. Rivara
Keyword(s):  
Primary Care ◽  
Health Care ◽  
Ambulatory Care ◽  
Difficult Problem ◽  
Precise Definition ◽  
Entry Point ◽  
Comprehensive Care ◽  
Preventative Care ◽  
Definition Of ◽  
Primary Care Pediatricians

I was very excited and pleased when I received my October 1977 issue of Pediatrics and found a supplement on primary care. However, with much disappointment I found that the articles included were, at best, focused on very narrow areas in pediatrics and, at worst, completely irrelevant to the current issues faced by primary care pediatricians in this country. The precise definition of primary care has been a difficult problem. One operative definition is a system of health care that provides for unselected problem care; comprehensive care; entry point care; preventative care; ambulatory care; and majority care.1

scholarly journals A Simulation Approach to the Definition of the Subsystems Parameters in Small Container Terminals

2021 ◽  
Vol 9 (9) ◽  
pp. 1023
Author(s):  
Maja Stojaković ◽  
Elen Twrdy
Keyword(s):  
Decision Support ◽  
Container Terminal ◽  
Decision Support Tool ◽  
Difficult Problem ◽  
Container Terminals ◽  
Simulation Approach ◽  
Support Tool ◽  
Small Container ◽  
Definition Of ◽  
Insight Into

This article deals with the extremely difficult problem faced by a large number of smaller ports: how to enable small container terminals to simultaneously receive two ships of post-Panamax size, and at the same time provide effective transshipment operations on an individual terminal subsystem, which would enable the fast turnaround of the ship in port and at the same time provide the port the possibility to increase annual traffic. For this purpose, a simulation approach was used in a hypothetical small size container terminal. The performed simulations covered all the berth-yard-berth operations focusing on the correct allocation of transfer mechanization to ensure optimal results on the sea side of the terminal. The results obtained were used to define the key parameters on the basis of which a Decision Support Tool was created. The aim of the Decision Support Tool is to help port operators to identify their current problems quickly and effectively and to give them an insight into the measures that need to be implemented to accommodate two post-Panamax ships at the terminal at the same time.

scholarly journals Deciding what to replicate: A formal definition of “replication value” and a decision model for replication study selection.

2020 ◽  
Author(s):  
Peder Mortvedt Isager ◽  
Robbie Cornelis Maria van Aert ◽  
Štěpán Bahník ◽  
Mark John Brandt ◽  
Kurt Andrew DeSoto ◽  
...  
Keyword(s):  
Expected Utility ◽  
Decision Model ◽  
General Rule ◽  
Difficult Problem ◽  
Current Evidence ◽  
Replication Studies ◽  
Study Selection ◽  
Utility Gain ◽  
Replication Research ◽  
Definition Of

Robust scientific knowledge is contingent upon replication of original findings. However, researchers who conduct replication studies face a difficult problem; there are many more studies in need of replication than there are funds available for replicating. To select studies for replication efficiently, we need to understand which studies are the most in need of replication. In other words, we need to understand which replication efforts have the highest expected utility. In this article we propose a general rule for study selection in replication research based on the replication value of the claims considered for replication. The replication value of a claim is defined as the maximum expected utility we could gain by replicating the claim, and is a function of (1) the value of being certain about the claim, and (2) uncertainty about the claim based on current evidence. We formalize this definition in terms of a causal decision model, utilizing concepts from decision theory and causal graph modeling. We discuss the validity of using replication value as a measure of expected utility gain, and we suggest approaches for deriving quantitative estimates of replication value.

scholarly journals Configural perception of a binary olfactory mixture in honey bees, as in humans, rodents and newborn rabbits

2020 ◽  
Vol 223 (21) ◽  
pp. jeb227611 ◽  
Author(s):  
Marie-Anne Wycke ◽  
Gérard Coureaud ◽  
Thierry Thomas-Danguin ◽  
Jean-Christophe Sandoz
Keyword(s):  
Difficult Problem ◽  
Proboscis Extension Response ◽  
Odor Quality ◽  
Complex Stimuli ◽  
General Rules ◽  
Odor Mixtures ◽  
Proboscis Extension ◽  
Invertebrate Model ◽  
Definition Of

ABSTRACTHow animals perceive and learn complex stimuli, such as mixtures of odorants, is a difficult problem, for which the definition of general rules across the animal kingdom remains elusive. Recent experiments conducted in human and rodent adults as well as newborn rabbits suggested that these species process particular odor mixtures in a similar, configural manner. Thus, the binary mixture of ethyl isobutyrate (EI) and ethyl maltol (EM) induces configural processing in humans, who perceive a mixture odor quality (pineapple) that is distinct from the quality of each component (strawberry and caramel). Similarly, rabbit neonates treat the mixture differently, at least in part, from its components. In the present study, we asked whether the properties of the EI.EM mixture extend to an influential invertebrate model, the honey bee Apis mellifera. We used appetitive conditioning of the proboscis extension response to evaluate how bees perceive the EI.EM mixture. In a first experiment, we measured perceptual similarity between this mixture and its components in a generalization protocol. In a second experiment, we measured the ability of bees to differentiate between the mixture and both of its components in a negative patterning protocol. In each experimental series, the performance of bees with this mixture was compared with that obtained with four other mixtures, chosen from previous work in humans, newborn rabbits and bees. Our results suggest that when having to differentiate mixture and components, bees treat the EI.EM in a robust configural manner, similarly to mammals, suggesting the existence of common perceptual rules across the animal kindgdom.

Tactics for Individual Productivity

1990 ◽  
Author(s):  
Steven Kim
Keyword(s):  
Difficult Problem ◽  
Careful Consideration ◽  
Candidate Solution ◽  
Challenging Tasks ◽  
Preparatory Phase ◽  
Individual Productivity ◽  
Adequate Definition ◽  
Definition Of ◽  
The Mind

The resolution of a difficult task often follows a series of identifiable steps. Students of creativity have often characterized the process as a four-stage phenomenon: • Preparation: Orientation to the problem and definition of the task. • Incubation: A period of aridity or immersion in unrelated activities. • Illumination: A sudden spark of insight and the recognition of a candidate solution. • Resolution: Assessment of the candidate solution and its implementation. The preparatory phase of a difficult task involves a careful consideration of the underlying problem and a clear specification of the goals. Too often we tackle tasks without an adequate definition of the true problem, and discover too late that the solution resolves an irrelevant problem. A distinguishing feature of challenging tasks lies in their resistance to attack, and solutions do not always spring from a single session of wrestling with the problem. Often difficult issues are resolved, whether gradually or suddenly, over spaced efforts interrupted by unrelated activities. Some students of creativity take the view that incubation is a period of “intermission” in which the problem submerges into the subconscious. The lack of strict conventions in this netherworld allows for the juxtaposition of new objects in novel and even bizarre combinations. The resulting ideas possess the novelty that is an essential ingredient of a creative solution. Other writers take the view that incubation is nothing more than a period of relaxation or recuperation in which a tired mind regains its energies. Still others would claim that the incubation phase is merely a stretch of time that allows the mind to assimilate other stimuli from the environment, whether at the conscious or subconscious level. Whatever the true role of incubation, the fact remains that many of our difficult problems are resolved only after several sessions of conscious effort separated by seemingly unrelated activities. A candidate solution to a difficult problem often occurs suddenly, just like the elementary ideas that constitute them. Such preliminary solutions or “insights,” however, can be misleading or even incorrect. For this reason, the ideas must be properly evaluated.

Finite Time Synchronization of Chaotic Systems Without Linear Term and Its Application in Secure Communication

2021 ◽  
Vol 15 (4) ◽  
pp. 54-78
Author(s):  
Shuru Liu ◽  
Zhanlei Shang ◽  
Junwei Lei
Keyword(s):  
Finite Time ◽  
Secure Communication ◽  
Chaotic Systems ◽  
Time Synchronization ◽  
Difficult Problem ◽  
Stable System ◽  
Convergence Time ◽  
Unknown Parameters ◽  
Communication Scheme ◽  
Definition Of

A definition of finite time synchronization of chaotic system was proposed, and a special theorem was proposed to solve the difficult problem of constructing a finite time stable system. After that, a hybrid construction method was proposed by integrating a common stable system and a finite time stable system. That reveals how to construct a finite time stable system, and it is very useful in secure communication since the convergence time is a very important factor that will affect its application in engineering realization. Above theorem and method was applied in the chaotic synchronization and two kinds of synchronization methods were proposed with estimation of unknown parameters. At last, a secure communication scheme was constructed by using above finite time synchronous method of chaotic systems. Also, numerical simulation was done, and the rightness of all the above proposed theorems and methods was shown.

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