Efficient and reliable surge prevention algorithm for centrifugal compressor

2020 ◽  
Vol 92 (1) ◽  
pp. 47-59
Author(s):  
Grzegorz Liśkiewicz
Keyword(s):  
Working Conditions ◽  
High Frequency ◽  
Experimental Studies ◽  
Phase Portraits ◽  
Centrifugal Blower ◽  
Local Flow ◽  
Content Type ◽  
Operating Range ◽  
Surge Margin ◽  
External Conditions

Purpose The paper aims to present an outline of the technology of the active anti-surge algorithm based on high-frequency pressure measurement. The presented system is fast, inexpensive and reliable and does not limit the machine-operating range. Many contemporary anti-surge systems are based on theoretical surge margin. This solution limits machine operating range by about 10-15 per cent in the region of the highest pressure ratios. It is also often sensitive to change in external conditions such as temperature or density, as the system reacts to limits calculated theoretically. Design/methodology/approach This paper presents results of pressure measurements obtained on the low-speed centrifugal blower DP1.12. The pressure signals were presented in the form of phase diagrams, and conclusions were drawn from their phase portraits to develop the surge indication parameter. Findings The presented safety system uses the signal to develop the so-called (rate of derivative fluctuation) RDF parameter. In nominal working conditions, this parameter keeps the value close to 1. When RDF reaches values over 3, the anti-surge procedure should be implemented. Experimental studies have shown that this algorithm assures enough time to incur actions suppressing unstable phenomena. Originality/value The system reacts to real machine working conditions and is hence reliable. The RDF algorithm could also be used to identify local flow instabilities, as well as off-design operation.

Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin
Keyword(s):  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Reduction Factor ◽  
Single Frequency ◽  
Cyclic Loads ◽  
Small Ratio ◽  
Harmonic Components ◽  
Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

Actual issues of hygienic regulation and creation of safe working conditions at pharmaceutical manufacturing enterprises

2020 ◽  
Vol 60 (10) ◽  
pp. 640-644
Author(s):  
Vadim M. Vasilkevich ◽  
Ruslan V. Bogdanov ◽  
Elena V. Drozdova
Keyword(s):  
Pharmaceutical Industry ◽  
Working Conditions ◽  
Experimental Studies ◽  
Pharmaceutical Products ◽  
Laboratory Animals ◽  
Production Environment ◽  
Basic Principles ◽  
Toxicological Studies ◽  
Health Disorders ◽  
Safe Working

Introduction. The working conditions of pharmaceutical industry workers are characterized by the combined effect of unfavorable factors of the production environment, among which the leading one is chemical. The aim of study is to substantiate the basic principles and criteria for hygienic regulation of pharmaceutical products in their production to ensure safe working conditions for employees based on the results of their own research and existing requirements of technical regulations. Materials and methods. Analysis of working conditions and the prevalence of health disorders in pharmaceutical workers (according to literature data), toxicological studies of pharmaceutical substances on laboratory animals, scientific justification of hygiene standards in the air of the working area. Results. Among employees of the pharmaceutical industry, the predominant forms of production-related health disorders are diseases of the respiratory system, as well as skin dermatitis of allergic origin, liver and biliary tract diseases. Based on the results of experimental studies of domestic pharmaceutical products for the treatment of cardiovascular, oncological and mental diseases that have priority socio-economic significance, the basic principles and features of the practice of justifying the hygienic standards of medicines in the air of the working area are developed and systematized. Conclusions. During hygienic rationing of medicines, it is necessary to use a differentiated approach that allows, based on the analysis of information about the chemical structure, physical and chemical characteristics, production conditions, pharmacotherapeutic activity, and the results of studying the toxic effect in an experiment on laboratory animals, to determine the maximum permissible content in the air of the working area of medicines or to justify the prohibition of isolation with reasoned recommendations for their safe production.

Posteroventral pallidotomy for midbrain tremor after a pontine hemorrhage

1999 ◽  
Vol 91 (5) ◽  
pp. 885-888 ◽  
Author(s):  
Yasushi Miyagi ◽  
Fumio Shima ◽  
Katsuya Ishido ◽  
Masashi Moriguchi ◽  
Kazufumi Kamikaseda
Keyword(s):  
Upper Extremity ◽  
High Frequency ◽  
Upper Extremities ◽  
Proximal Segment ◽  
Action Tremor ◽  
Content Type ◽  
Pontine Hemorrhage ◽  
Posteroventral Pallidotomy ◽  
Left Thalamus ◽  
Midbrain Tremor

✓ This 49-year-old man gradually developed a disabling action tremor in the proximal right upper extremity 8 months after suffering a pontine tegmental hemorrhage. The intraoperative microrecording in the nucleus ventralis intermedius (VIM) of the left thalamus revealed tremor-synchronous grouped discharges with a vigorous (2.7 Hz) action tremor predominantly in the shoulder and upper arm. High frequency electrical stimulation in the VIM did not affect the tremor. A posteroventral pallidotomy (PVP) was performed and resulted in the successful alleviation of all tremor activity. Posteroventral pallidotomy is known to alleviate parkinsonian tremors, especially those occurring in the contralateral lower extremity, trunk, and proximal segment of the contralateral upper extremity. The authors consider the pallidoreticular pathway to be an important tremor-mediating pathway for the proximal segment of the upper extremities and believe it can be controlled more effectively by PVP than by VIM thalamotomy, as demonstrated by the PVP-induced resolution of the midbrain tremor observed in this case.

The dependence structure in volatility between Shanghai and Shenzhen stock market in China

2016 ◽  
Vol 6 (3) ◽  
pp. 264-283 ◽  
Author(s):  
Mingyuan Guo ◽  
Xu Wang
Keyword(s):  
Stock Market ◽  
High Frequency ◽  
Estimation Method ◽  
Garch Model ◽  
Price Volatility ◽  
Market Volatility ◽  
High Frequency Data ◽  
Dependence Structure ◽  
Frequency Data ◽  
Content Type

Purpose – The purpose of this paper is to analyse the dependence structure in volatility between Shanghai and Shenzhen stock market in China based on high-frequency data. Design/methodology/approach – Using a multiplicative error model (hereinafter MEM) to describe the margins in volatility of China’s Shanghai and Shenzhen stock market, this study adopts static and time-varying copulas, respectively, estimated by maximum likelihood estimation method to describe the dependence structure in volatility between Shanghai and Shenzhen stock market in China. Findings – This paper has identified the asymmetrical dependence structure in financial market volatility more precisely. Gumbel copula could best fit the empirical distribution as it can capture the relatively high dependence degree in the upper tail part corresponding to the period of volatile price fluctuation in both static and dynamic view. Originality/value – Previous scholars mostly use GARCH model to describe the margins for price volatility. As MEM can efficiently characterize the volatility estimators, this paper uses MEM to model the margins for the market volatility directly based on high-frequency data, and proposes a proper distribution for the innovation in the marginal models. Then we could use copula-MEM other than copula-GARCH model to study on the dependence structure in volatility between Shanghai and Shenzhen stock market in China from a microstructural perspective.

Think about it – can portrayals of homosexuality in advertising prime consumer-perceived social connectedness and empathy?

2017 ◽  
Vol 51 (1) ◽  
pp. 82-98 ◽  
Author(s):  
Nina Åkestam ◽  
Sara Rosengren ◽  
Micael Dahlen
Keyword(s):  
Design Methodology ◽  
Social Connectedness ◽  
Experimental Studies ◽  
Social Effects ◽  
Attitudes Toward Homosexuality ◽  
Content Type ◽  
Advantages And Disadvantages ◽  
Thought Listing ◽  
Societal Level ◽  
Practical Implications

Purpose This paper aims to investigate whether portrayals of homosexuality in advertising can generate social effects in terms of consumer-perceived social connectedness and empathy. Design/methodology/approach In three experimental studies, the effects of advertising portrayals of homosexuality were compared to advertising portrayals of heterosexuality. Study 1 uses a thought-listing exercise to explore whether portrayals of homosexuality (vs heterosexuality) can evoke more other-related thoughts and whether such portrayals affect consumer-perceived social connectedness and empathy. Study 2 replicates the findings while introducing attitudes toward homosexuality as a boundary condition and measuring traditional advertising effects. Study 3 replicates the findings while controlling for gender, perceived similarity and targetedness. Findings The results show that portrayals of homosexuality in advertising can prime consumers to think about other people, thereby affecting them socially. In line with previous studies of portrayals of homosexuality in advertising, these effects are moderated by attitudes toward homosexuality. Research limitations/implications This paper adds to a growing body of literature on the potentially positive extended effects of advertising. They also challenge some of the previous findings regarding homosexuality in advertising. Practical implications The finding that portrayals of homosexuality in advertising can (at least, temporarily) affect consumers socially in terms of social connectedness and empathy should encourage marketers to explore the possibilities of creating advertising that benefits consumers and brands alike. Originality/value The paper challenges the idea that the extended effects of advertising have to be negative. By showing how portrayals of homosexuality can increase social connectedness and empathy, it adds to the discussion of the advantages and disadvantages of advertising on a societal level.

Assessment of patient safety culture during COVID-19: a cross-sectional study in a tertiary a-level hospital in China

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chih-Hsuan Huang ◽  
Ying Wang ◽  
Hsin-Hung Wu ◽  
Lee Yii-Ching
Keyword(s):  
Patient Safety ◽  
Working Conditions ◽  
Emotional Exhaustion ◽  
Safety Culture ◽  
Team Building ◽  
Reliability And Validity ◽  
Patient Safety Culture ◽  
Cross Sectional ◽  
Content Type ◽  
Safety Attitudes

PurposeThe aims of this study are to (1) evaluate physicians and nurses' perspectives on patient safety culture amid the COVID-19 pandemic and (2) integrate the emotional exhaustion of physicians and nurses into an evaluation of patient safety culture to provide insights into appropriate implications for medical care.Design/methodology/approachPatient safety culture was assessed with the Chinese version of the Safety Attitudes Questionnaire. Confirmatory factor analysis was conducted to validate the structure of the data (i.e. reliability and validity), and Pearson's correlation analysis was performed to identify relationships between safety-related dimensions.FindingsSafety climate was strongly associated with working conditions and teamwork climate. In addition, working conditions was highly correlated with perceptions of management and job satisfaction, respectively. It is worth noting that the stress and emotional exhaustion of the physicians and nurses during this epidemic were high and needed attention.Practical implicationsFor healthcare managers and practitioners, team-building activities, power of public opinions, IoT-focused service, and Employee Assistance Programs are important implications for inspiring the patient safety-oriented culture during the period of the COVID-19 pandemic.Originality/valueThis paper considers the role of emotional state into patient safety instrument, a much less understood but equally important dimension in the field of patient safety.

The interactive effect of insight and cuteness in driving purchase likelihood: a lay belief of creativity

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Felix Septianto ◽  
Rokhima Rostiani ◽  
Widya Paramita
Keyword(s):  
New Products ◽  
Interactive Effect ◽  
Experimental Studies ◽  
New Product ◽  
Underlying Mechanism ◽  
Content Type ◽  
Narrative Study ◽  
Managerial Implications ◽  
Purchase Likelihood

PurposeWhile new product introductions can potentially promote growth and benefit for brands, it remains unclear how marketers can develop effective communication strategies to increase the chance of success for new products. The present research investigates the role of cuteness in leveraging the effectiveness of a narrative emphasizing an insight versus an effort in this regard.Design/methodology/approachThis research presents two experimental studies. Study 1 examines the moderating role of cuteness on the likelihood of purchasing a new product featuring an insight-based (vs effort-based) narrative. Study 2 extends the findings of Study 1 using different stimuli and establishes the underlying mechanism.FindingsResults show that when a cuteness appeal is present, an insight-based (vs effort-based) narrative will lead to a higher purchase likelihood. However, these differences do not emerge when a cuteness appeal is absent (a control condition). Further, perceived brand creativeness will mediate this effect.Originality/valueThe findings of this research contribute to the literature on lay belief of creativity, cuteness, and product narrative, as well as managerial implications on how to promote new products.

Effect Of The Rib Inclination Angle On Liquid Film Spreading Over The Structured Surface

2015 ◽  
Vol 10 (1) ◽  
pp. 42-49
Author(s):  
Aleksandr Pavlenko ◽  
Oleg Volodin ◽  
Vladimir Serdyukov
Keyword(s):  
Liquid Film ◽  
Flow Rate ◽  
Inclination Angle ◽  
High Speed ◽  
Film Flow ◽  
Complex Geometry ◽  
Experimental Studies ◽  
Local Flow ◽  
Structured Packing ◽  
Film Spreading

Results of experimental studies on hydrodynamics of the film flow of liquid nitrogen over the surface of the single elements of structured packing are presented. The effect of inclination angle of the large ribs and perforation on the zones of liquid film spreading over the corrugated surface with microtexture at different Reynolds numbers of the film is shown based on a comparison of experimental data. It is shown that the angle of large rib inclination has a significant influence on redistribution of the local flow rate of liquid flowing on the surface with complex geometry. Analysis of results of the high-speed video revealed that in a vicinity of the vertical lateral edges of corrugated plates, the intense rivulet flows are formed, including those with separation from the film flow surface. This negative factor can lead to significant liquid accumulation and flow near the vertical edges of the structured packing and on the inner wall of the heat exchanging apparatuses and, finally, to a significant increase in the degree of maldistribution of local liquid flow rate over the crosssection, for instance, of the distillation columns.

scholarly journals High Frequency of OXA-253-Producing Acinetobacter baumannii in Different Hospitals in Recife, Brazil

2016 ◽  
Vol 61 (1) ◽  
Author(s):  
Felipe Lira de Sá Cavalcanti ◽  
Carina Lucena Mendes-Marques ◽  
Crhisllane Rafaele dos Santos Vasconcelos ◽  
Túlio de Lima Campos ◽  
Antonio Mauro Rezende ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
High Frequency ◽  
Resistance Determinant ◽  
Large Area ◽  
Content Type ◽  
Successful Transmission ◽  
Genetic Environment ◽  
Reported Data ◽  
Sequence Types

ABSTRACT Here, we report the isolation of 31 Acinetobacter baumannii strains producing OXA-253 in a single large Brazilian city. These strains belonged to five different sequence types (STs), including 4 STs not previously associated with bla OXA-253. In all strains, the bla OXA-253 gene was located in a plasmid within a genetic environment similar to what was found previously in Brazil and Italy. The reported data emphasize the successful transmission of the bla OXA-253 gene through a large area and the tendency for this resistance determinant to remain in the A. baumannii population.

Recent civil and criminal enforcement action involving high frequency trading

2015 ◽  
Vol 16 (1) ◽  
pp. 5-12 ◽  
Author(s):  
Matthew Rossi ◽  
Greg Deis ◽  
Jerome Roche ◽  
Kathleen Przywara
Keyword(s):  
High Frequency ◽  
Design Methodology ◽  
High Frequency Trading ◽  
Content Type ◽  
Enforcement Action ◽  
The Past ◽  
Trading Patterns ◽  
Federal Prosecutor ◽  
Enforcement Activity ◽  
Practical Implications

Purpose – To alert high frequency trading firms to the increased regulation and prosecution of manipulative trading practices during 2014 and early 2015. Design/methodology/approach – Reviews four significant proceedings against high frequency trading firms (and/or individuals employed by such firms) and other developments from the relevant government agencies as a possible preview of the enforcement and prosecution of high frequency trading practices in 2015. Provides advice to high frequency trading firms on how to decrease the risk of regulatory or criminal actions against them in this changing environment. Findings – Although the focus on high frequency trading has only recently begun to intensify, firms should be aware of the increased enforcement activity of the past year. These actions, both regulatory and criminal, have already resulted in large penalties and have helped initiate a strengthening of rules and regulations regarding manipulative trading practices, of which firms need to be aware and stay current. Practical implications – High frequency trading firms should be aware of the recent regulatory and criminal actions in order to better evaluate their own practices and controls, to ensure that their trading patterns do not resemble manipulative practices, and to avoid similar actions. Originality/value – Practical guidance from experienced litigators and securities regulatory lawyers, including a former SEC Assistant Chief Litigation Counsel and a former federal prosecutor, that consolidates and describes several recent actions and developments in one piece.

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