scholarly journals Temperature-entropy diagrams for calculating cycles of refrigerating machines using refrigerant mixtures

2020 ◽  
Vol 2020 (4) ◽  
pp. 79-86
Author(s):  
Vladimir Grigorievich Bukin ◽  
Alexey Vasilievich Ezhov ◽  
Aleksander Ivanovich Andreev
Keyword(s):  
Energy Characteristics ◽  
Advantages And Disadvantages ◽  
Boiling Points ◽  
Refrigerant Mixtures ◽  
Liquid Phases ◽  
First Case ◽  
Pure Substances ◽  
Temperature Levels ◽  
Internal Irreversibility ◽  
Working Bodies

The article represents the advantages and disadvantages of refrigeration machines operating on non-azeotropic refrigerant mixtures. There has been illustrated their specific feature in comparison with pure substances: they are non-isothermal during phase transitions. It can be effective when cooling or heating flows that significantly change the temperature, and ineffective when working with volumes, where it is necessary to maintain a constant temperature. In the first case there takes place a decrease in the internal irreversibility of heat transfer processes in evaporators and condensers; in the second case - an increase. When using mixed refrigerants, it is possible to simultaneously obtain several temperature levels in a single-stage machine at the same pressure in the evaporators, they can obtain low boiling points of the refrigerant without vacuum in the evaporator and regulate the refrigeration capacity of the machine by changing the composition of the mixture. The prospects of using mixtures of working bodies of refrigerating machines have been proved. The diagrams T-S, T-ξ, i-ξ are presented allowing to calculate the cycle of the machine, to determine its operating parameters and to calculate the technical and energy characteristics. The developed thermal diagrams make it possible to accurately examine the dynamics of the boiling and condensation processes of a binary mixture, show the change in the concentration of the mixture in the vapor and liquid phases and make it possible to construct and calculate the cycle of a refrigeration machine operating on a mixed refrigerant. Examples of constructing cycles of two schemes of refrigeration machines operating on a mixed refrigerant are considered: with separation of the working substance flow and without separation. Methods for calculating the cycle are provided

scholarly journals Possibility of Slag Sensible Heat Recovery on Drum-like Installations

2020 ◽  
Author(s):  
Yu.V. Sorokin ◽  
B.L. Demin ◽  
L.A. Smirnov ◽  
Ye.N. Shcherbakov
Keyword(s):  
High Temperature ◽  
Heat Recovery ◽  
Heat Content ◽  
Sensible Heat ◽  
Energy Characteristics ◽  
Working Bodies ◽  
Physical Heat

A variant of utilizing of slag physical heat in drum-like installations has been considered. A high-temperature melt is delivered to movable metal bodies. Heat is picked up from the working bodies surface and newly generated surfaces of slag due to interaction with working bodies. Surface of slag grains, as they cool down, allows to pick up heat with various energy characteristics. Keywords: smelter slags, heat content, drum-like installations, picking up and utilization of heat with various energy characteristics

scholarly journals Deformation of cranioplasty titanium mesh in a paediatric patient following head trauma

2019 ◽  
Vol 12 (6) ◽  
pp. e230421
Author(s):  
Basel Sharaf ◽  
Malke Asaad ◽  
Joseph Banuelos ◽  
Jesse Meaike
Keyword(s):  
Paediatric Patient ◽  
Head Trauma ◽  
Titanium Mesh ◽  
Brain Protection ◽  
Contact Sports ◽  
Advantages And Disadvantages ◽  
First Case ◽  
Alloplastic Materials ◽  
Life Saving ◽  
Titanium Cranioplasty

Decompressive craniectomy is a life-saving procedure performed to treat intracranial hypertension caused by a variety of conditions. Subsequent cranioplasty reconstruction is needed for brain protection. Different alloplastic materials with different advantages and disadvantages are available for cranial reconstruction. We present the first case of a deformed titanium cranioplasty mesh in a paediatric patient following head trauma. Children who have undergone cranioplasty reconstruction should be counselled to wear a protective helmet when involved in contact sports or activities that may put their implant at risk of trauma.

Working Body for Deformation of Thin-Walled Pipe Billets

2019 ◽  
Vol 945 ◽  
pp. 628-633 ◽  
Author(s):  
S.B. Maryin ◽  
Phyo Wai Aung
Keyword(s):  
Production Costs ◽  
Compression Load ◽  
Advantages And Disadvantages ◽  
Different Types ◽  
Thin Walled Pipe ◽  
Thin Walled ◽  
Working Bodies ◽  
Fast Flow ◽  
Rigid Matrix ◽  
Transfer Pressure

In this paper we consider different types of working bodies and fillers used in the manufacture of hydro-gas systems of aircraft from thin-walled pipe billets, and also explored the advantages and disadvantages of liquid, fusible, solid, elastic, loose and combined fillers in the deformation of pipe segments by means of distribution, crimping, forming and flexible. As a result of the research, a device for distributing pipe billets along a rigid matrix and a working body made of granular polyurethane and ice, the main advantages of which are: good rheological properties (fast flow); high ductility and viscosity; high ability to transfer pressure throughout the metal zone; ability to withstand high compression load; ease of entry into the workpiece and removal from the finished part; low production costs.

Chemical actinometry (IUPAC Technical Report)

2004 ◽  
Vol 76 (12) ◽  
pp. 2105-2146 ◽  
Author(s):  
H. J. Kuhn ◽  
S. E. Braslavsky ◽  
R. Schmidt
Keyword(s):  
Electronic Devices ◽  
Absolute Measurement ◽  
Chemical Reactor ◽  
Chemical System ◽  
Photon Flux ◽  
Advantages And Disadvantages ◽  
Liquid Phases ◽  
Standard Procedures ◽  
Technical Report ◽  
Incident Photon Flux

This document updates the first version of the IUPAC technical report on “Chemical actinometers” published in Pure Appl. Chem. 61 ,187-210 (1989). Since then, some methods have been improved, procedures have been modified, and new substances have been proposed as chemical actinometers. An actinometer is a chemical system or a physical device by which the number of photons in a beam absorbed into the defined space of a chemical reactor can be determined integrally or per time. This compilation includes chemical actinometers for the gas, solid, microheterogeneous, and liquid phases, as well as for the use with pulsed lasers for the measurement of transient absorbances, including the quantum yield of phototransformation, as well as the literature for each of the actinometers. The actinometers listed are for the use in the wavelength range from the UV to the red region of the spectrum. A set of recommended standard procedures is also given. Advantages and disadvantages are discussed regarding the use of chemical actinometers vs. electronic devices for the measurement of the number of photons absorbed. Procedures for the absolute measurement of incident photon flux by means of photodiodes are also discussed.

scholarly journals RISK APPETITE ASSESSMENT FRAMEWORK

2020 ◽  
pp. 35-46
Author(s):  
Iryna Fedulova ◽  
Nataliia Skopenko
Keyword(s):  
Maximum Level ◽  
Risk Tolerance ◽  
Qualitative Assessment ◽  
Managerial Decision ◽  
Advantages And Disadvantages ◽  
Business Goals ◽  
Qualitative Approaches ◽  
First Case ◽  
Risk Appetite ◽  
Risk Event

he adoption of any managerial decision within the company happens in the presence of risks. Against this background, it is vital to determine whether the risk is acceptable for achieving the objectives. In the article the essence of risk appetite, risk tolerance and risk capacity is considered. Differences between risk capacity, risk appetite and risk tolerance are defined. Risk appetite reflects the level of losses that the company is willing to accept in order to achieve its strategic objectives. In contrast, risk tolerance is related to the acceptance of the outcomes of specific identified risk events and is defined as readiness for certain risk event. Risk capacity is the maximum level of risk that an organization is able to accept for achieving its business goals, taking into account the current level of resources, its capital structure and access to markets. An important part of identifying the risk appetite for the company is a description of advantages and disadvantages of existing methods of its assessment. Quantitative and qualitative approaches to determining risk appetite are considered. In the first case, the absolute value of possible risk or its relative value is established. In this case, the risk appetite is determined depending on organizational objectives. These objectives may determine the achievement of the planned financial indicators, compliance with financial regulations and other indicators of the company. Qualitative assessment of risk appetite is used when the risk cannot be quantified. In this case, the risk appetite is presented in a descriptive way. It is important to define the risk appetite including all aspects of the enterprise activity in the context of certain strategic goals of its development. Breaching the risk tolerance threshold should serve as a red alert for management. In such a case, it is important to reduce the risk position.

USE OF THE ALTERNATIVE TECHNICAL CONCEPTS IN TRANSPORTATION PROJECTS

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Ali Touran ◽  
Firooz Panah
Keyword(s):  
The United States ◽  
Department Of Transportation ◽  
Advantages And Disadvantages ◽  
Transportation Projects ◽  
First Case ◽  
Best Value ◽  
Federal Highway ◽  
Design Build ◽  
Request For Proposal ◽  
Selection Of

The use of Alternative Technical Concepts (ATC) is becoming widespread in design-build transportation projects in the United States. According to Federal Highway Administration (FHWA) ATC is a request by a proposer (usually in design-build projects) to modify a contract requirement for gaining competitive advantage over competition. The owner, usually a state department of transportation, requires that the ATC provide a better or at least equal solution to the owner’s design requirements. In Design-Build (DB) projects, the ATC is usually proposed by a proposer during the Request for Proposal (RFP) process and is considered in the evaluation and selection of the proposers in conjunction with the Best Value (BV) method of selection. In this paper, the authors have focused on two case studies involving ATC implementation and negotiations with the Massachusetts Department of Transportation (MassDOT) highlighting advantages and disadvantages of using ATC in DB contracts. In each case, the nature of ATC and the approval process is discussed. In the first case, the approved ATCs provided the proposer with a clear advantage in winning a contract with the agency despite not being the low bidder. In the second case, the proposed and approved ATCs did not result in winning a contract despite being the low bidder.

scholarly journals Eagle’s syndrome - a report of two cases

2015 ◽  
Vol 72 (5) ◽  
pp. 458-462 ◽  
Author(s):  
Aleksandar Kiralj ◽  
Miroslav Ilic ◽  
Bojan Pejakovic ◽  
Borislav Markov ◽  
Sasa Mijatov ◽  
...  
Keyword(s):  
Surgical Techniques ◽  
Styloid Process ◽  
Surgical Approaches ◽  
Advantages And Disadvantages ◽  
Postoperative Control ◽  
First Case ◽  
Intraoral Approach ◽  
Body Sensation ◽  
Eagle Syndrome ◽  
Stylohyoid Ligament

Introduction. Eagle?s syndrome is defined as elongation of the styloid process or the stylohyoid ligament mineralization complex which consist of styloid process, stylohyoid ligament and lesser horn of hyoid bone. It is a rare entity, is not commonly suspected in clinical practice. It is characterized by recurrent facial and throat pain, dysphagia, odynophagia, parapharingeal foreign body sensation, otalgia and neck pain. Eagle?? syndrome can be treated conservatively (lacing local anesthetic into the styloid process and stylomandibular ligament attachment) or surgically. Its pathogenesis and threatment modalities are still being debated while different theories have been presented. Case report. The two traditional surgical approaches to styloidectomy (removal of the elongated portion of the styloid process) were presented the intraoral approach and the extraoral approach. We presented two cases (49 years and 34 years old males), with bilateral and unilateral elongated styloid process. The surgical treatment included unilateral right side stiloidectomy by intraoral approach in the first case and right styloidectomy by extraoral approach in the second case. In both eases post-operative course passed regularly with no complaints at regular postoperative control. Conclusion. Surgical techniques for treatment of Eagle?s syndrome have many advantages and disadvantages. We believe that the length of the styloid process or the calcified ligament is a decisive parameter for the selection of techniques and approach.

scholarly journals Estudio de viabilidad económica de una central termosolar de 50 MW con y sin almacenamiento térmico = Economic feasibility study in a cylindrical-parabolic solar thermal plant of 50 MW with and without thermal storage

2016 ◽  
pp. 1
Author(s):  
Pedro José Soto Piedehierro ◽  
Alfonso Isidro López Díaz
Keyword(s):  
Feasibility Study ◽  
Thermal Storage ◽  
Economic Feasibility ◽  
The Other ◽  
Solar Thermal ◽  
Thermal Plant ◽  
Advantages And Disadvantages ◽  
First Case

<p>Este articulo trata sobre el estudio de viabilidad económica de una central termosolar cilíndrico-parabólica de 50 MW en el término municipal de Badajoz. Para ver las diferentes alternativas en el diseño y estudio económico de la instalación se han tenido en cuenta dos casos, un primer caso de la central sin almacenamiento térmico y un segundo caso de la central con almacenamiento térmico. La finalidad con la que se presenta este estudio es analizar los diferentes casos y presentar conclusiones al respecto.</p><p>The aim of this study is to do an economic feasibility study in a cylindrical-parabolic solar thermal plant of 50 MW in Badajoz. Two different cases have been studied, first case the solar thermal plant without thermal storage and the other case, the solar thermal plant with thermal storage (salt tanks). The advantages and disadvantages of the use of each element have also been analyzed.</p>

scholarly journals Ophthalmoscopy in dog and cat

2018 ◽  
Vol 52 (3) ◽  
pp. 214
Author(s):  
I. Κ. LIAPIS (Ι. Κ. ΛΙΑΠΗΣ)
Keyword(s):  
Optical Field ◽  
General View ◽  
Fundus Examination ◽  
Special Equipment ◽  
Advantages And Disadvantages ◽  
Reflection And Refraction ◽  
Indirect Ophthalmoscopy ◽  
First Case ◽  
Indirect Technique ◽  
Direct Ophthalmoscopy

Ophthalmoscopy is the procedure for fundus examination. As an examining technique, ophthalmoscopy is based on the principles of reflection and refraction of the light. In the first case (reflection of the light) ophthalmoscopy is direct. In the second case (reflection and refraction of the light) ophthalmoscopy is indirect. For direct ophthalmoscopy a simple light source is used or better yet a special ophthalmoscope. The indirect technique is realised with the assistance of special equipment. Each one of the above mentionned methods has advantages and disadvantages and it's better having them coherent to one another. The indirect ophthalmoscopy gives a general view of the fundus and magnifies it satisfactorily, whereas direct ophthalmoscopy even though provokes better magnification, gives a smaller optical field.

The viscosity of pure substances in the dense gaseous and liquid phases

AIChE Journal ◽  
1962 ◽  
Vol 8 (1) ◽  
pp. 59-63 ◽  
Author(s):  
John A. Jossi ◽  
Leonard I. Stiel ◽  
George Thodos
Keyword(s):  
Liquid Phases ◽  
Pure Substances
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