Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

Analysis of High Mach 2DCD and SERN Scale Model Test Data

1993 ◽  
Author(s):  
G. E. Hoff ◽  
R. W. Whittaker
Keyword(s):  
Test Data ◽  
Performance Test ◽  
Development Program ◽  
External Flow ◽  
Operating Conditions ◽  
Scale Model ◽  
Prediction Methods ◽  
Study Results ◽  
Nozzle Pressure ◽  
High Mach

This paper presents the results of analysis of scale model cold flow static performance test data for 2DCD and SERN High Mach (4 to 6) nozzle configurations generated under a GE Aircraft Engines Independent Research and Development Program. The testing was conducted at FluiDyne Engineering Corporation in late 1989. For the 2DCD nozzles, throat area, divergent flap length, contour, expansion ratio, and nozzle pressure ratio were parametrically varied and simulated operating conditions from subsonic to Mach 6. SERN nozzle parameters varied included throat area, expansion ramp length, cowl length and cowl divergence angle. Geometrics and nozzle pressure ratios simulated subsonic to Mach 6 operation. Although these tests were conducted statically, i.e., external flow was not simulated, the analysis presented herein addresses design point performance where the internal performance is not expected to be significantly influenced by external flow. Data from the test program have been examined for comparison with existing GE performance prediction methods. A second objective was to explore generalization of the data for the preparation of prediction methodologies and design guides for future High Mach propulsion system studies. In general, the study results presented in this paper indicate that current GE 2DCD prediction methods do not extrapolate to the High Mach nozzle regime. Also presented are general performance trends as a function of key geometric parameters and potential correlating factors which provide guidelines for the design of future High Mach exhaust systems.

Efficiency Upgrade of a Double-Case Pump Using CFD-Based Design Optimization and Scaled Model Tests

2015 ◽  
Author(s):  
Martijn van der Schoot ◽  
Frank Visser
Keyword(s):  
Design Optimization ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Model Tests ◽  
Operating Conditions ◽  
Pump Efficiency ◽  
Scaled Model ◽  
Cross Sectional ◽  
Optimization Study ◽  
Internal Component

This paper presents a design optimization study of a low specific-speed, multistage, double-case, volute pump. The goal of this study was to accomplish an increase in overall pump efficiency by at least 3.5 percentage points. To that end, each hydraulic internal component of the pump was analyzed to find opportunities for improvement. This was done by performing a combined classical hydraulic evaluation and in-depth Computational Fluid Dynamics (CFD) analysis. The hydraulic assessment gives a good overview if the component is suitable for the desired operating conditions in a relatively quick manner. It is, however, not suitable for detailed understanding of why a certain component is underperforming. Pump internals typically have a complex three-dimensional shape, which is not taken into consideration when performing a classical analysis. Therefore, a three-dimensional CFD simulation was performed to identify in detail the potential areas for improvement of each component. Two different strategies were used for optimizing the internal components. The series impeller geometry was optimized automatically by an objective algorithm to obtain optimum performance; other components, including first-stage impeller, series volutes and short crossovers were redesigned by manual design iterations, which were evaluated using CFD. The results show that the distribution of the cross-sectional area in the crossovers had the greatest influence on the efficiency, and due effort was undertaken to optimize this. To validate the efficiency improvement that was predicted by CFD simulations, scaled model tests were conducted on the series stages. The entire design optimization resulted in better performance in terms of efficiency, power and head for the complete flow range.

ASSESSMENT OF SKILLED BIRTH ATTENDANTS REGARDING HELPING BABIES BREATH INTERVENTION TO IMPROVE NEWBORN CARE IN RURAL DISTRICT OF SINDH

1970 ◽  
Vol 7 (1) ◽  
pp. 48-53
Author(s):  
Sheh Mureed ◽  
Muhammad Hassan Gandro ◽  
Walid Hassan
Keyword(s):  
Newborn Care ◽  
Cross Sectional Study ◽  
Vital Role ◽  
Skilled Birth Attendants ◽  
Cross Sectional ◽  
Neonatal Deaths ◽  
Birth Attendants ◽  
Study Results ◽  
Knowledge And Practice ◽  
Labour Room

Background: Globally, 3.1 million newborn deaths occur every year out of these estimated 400,000 neonatal deaths occur in Pakistan. All neonatal deaths 99% take place in poorest region and countries of the world, usually within hours of birth; mostly the cause of neonatal deaths is hypoxia. To access knowledge and practice of SBAs regarding HBB and to access the availability of equipments required for HBB. Methods: Descriptive Cross-Sectional Study on SBAs as trained in HBB. All 46 SBAs trained on HBB working in Labour room eight rural Health centers, four Taluka, One district Head Quarter Health Facilities and thirteen Mlbcs of the district, were included in the sample for study. All 41 SBAs were trained on HBB participated in the study. Results: Mean age of 30 years. Out of total 41 participants 25 were working in B-EmoNC (61%), 3in C-EmoNC (7.3%) and 13 in mid wife laid birth Centre (MLBC) or birth station (31.7%). About 92.7% of participants said that main purpose of HBB training is to decrease the NMR by improving newborn care. Drying of newborn is 82.7%, hand washing is 95.12% and 85.3% of the study participants said that they gave 30-40 breaths per minutes. Cord clamp and pair of ties was accessible to 85% of participants versus 14.3% who reported it's not accessible. Almost one quarter (34.1%) participants have low knowledge and practice. Knowledge and training had significant effect on the overall practices of the skilled birth attendants for skilled birth deliveries and reduce the neonatal deaths (P <0.001). Conclusion: Tools play a vital role for the implication of the knowledge into practices and tools were available almost to every participant. Although few barriers also identified for the less application of the helping hand babies trainings in the community.

COMPARISION OF DENTAL SCORING SYSTEM WITH RADIOGRAPHIC SKELETAL SYSTEM IN AGE ESTIMATION

JKCD ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 9-11
Author(s):  
Sadaf Ambreen
Keyword(s):  
Age Estimation ◽  
Scoring System ◽  
Skeletal Age ◽  
Chronological Age ◽  
Age Group ◽  
Dental Age ◽  
Scoring Method ◽  
Cross Sectional ◽  
Study Results ◽  
Male Subjects

Objectives: To compare Demirjian Dental scoring method with Greulich-Pyle (GP) Skeletal method of age estimation in pubertal children. Materials and Methods: Sample of the study included 267 male healthy subjects of 11-16 years of age group.. Demirjian Scoring system was utilized to evaluate the orthopantomograms to assess their Dental age and the Hand-Wrist radiographs were analyzed to calculate the skeletal age by utilizing GP atlas. Chronological age was obtained from the date of birth of the subject .Both methods were compared with one another and with the chronological age. It was a cross-sectional study and only healthy male subjects without any clinical abnormalities were included in the study. Results: A total of 267 male subjects of 11-16 years of age group were assessed by Demirjian and Greulich Pyle Methods. Both were compared with Chronological Age. Data obtained was statistically analyzed and the Student “t” test was applied in the study population. The mean difference between Chronolgical age and dental age was 0.69years and that of chronological age and skeletal age was 0.87 years. It was observed from dental age assessment that it does not differ much from the skeletal age. Conclusion: It was concluded that Demirjian method of Age Estimation is more precise than Greulich Pyle method of Age Estimation. Furthermore both methods can be used selectively in Medicolegal cases to access bone age which can be easily correlated to chronological age.

Blood Analysis Requests of Patients’ and Clinical Reflections in Primary Care

2020 ◽  
Vol 9 (2) ◽  
pp. 96-102
Author(s):  
Zerrin Gamsizkan ◽  
Mehmet Ali Sungur ◽  
Yasemin Çayır
Keyword(s):  
Chronic Disease ◽  
Blood Test ◽  
Family Health ◽  
Cross Sectional Study ◽  
Blood Analysis ◽  
Primary Role ◽  
Cross Sectional ◽  
High Expectations ◽  
Blood Tests ◽  
Study Results

Aim: The aim of the study is to determine the factors that may affect the demands of patients who come with the request to have a blood test without any chronic disease or a planned examination check. Methods: The data of this descriptive, cross-sectional study, were collected with a questionnaire that was prepared to examine the opinions of the patients who claim to have a blood test by coming to the family health center without any complaints. Patients over 18 years of age, who did not have any chronic disease and had no scheduled examination appointments were included in the study. Results: A total of 278 patients who wanted to have a blood test within the 6-months period were included in the study. Female patients who wanted to have a blood test were significantly more than male patients. When we look at the causes of patients who wanted to have a blood test; 61.2% (n=170) patients stated that they are concerned about their health and 6.1% (n=17) stated that they were affected by media warnings. There was no significant relationship between the frequency of blood test requests of patients and their age, gender, education, and general health status. Conclusion: Patients with high expectations and anxiety may be more willing to perform blood tests at inappropriate intervals. Family physicians, whose primary role is preventive medicine, have consultancy and information duties in order to protect their patients from the risk of over-examination and diagnosis. Keywords: blood tests, patient, screening, routine diagnostic tests

HIV INFECTION AND SOME RELATED FACTORS IN FEMALE MASSAGE THERAPISTS IN QUANG NGAI PROVINCE

2015 ◽  
pp. 57-60
Author(s):  
Xuan Chuong Tran ◽  
Thi Thanh Hoa Le ◽  
Ngoc Van Nguyen ◽  
Thanh Nguyen
Keyword(s):  
Hiv Infection ◽  
Urban Areas ◽  
Risk Groups ◽  
Sexual Contact ◽  
Related Factor ◽  
Related Factors ◽  
Cross Sectional ◽  
Keywords Hiv ◽  
Study Results ◽  
Massage Therapists

Background: HIV/AIDS is still a dangerous infection in Vietnam and in the world. Studying of HIV infection and related factors in high risk groups, including female massage therapists is therefore very important. Aims: 1. To study the HIV infection in female massage therapists in Quang Ngai province. 2. To fine some related factors to HIV infection. Patients and methods: Female massage therapists working in Quang Ngai province. Cross-sectional, descriptive study. Results: The rate of HIV infection was 0.99%. Group older than 22 years old had higher rate of infection than group under 22 years old (1.80% vs 0.69%). The girls from urban areas or not using condom had higher rate of infection than group from rural or not using condom (1.57% vs 0.47% and 7.32% vs. 0.57%). Most of HIV infected belong to single or divorce groups. Conclusions: The rate of HIV infection in female massage therapists in Quang Ngai province was 0.99%. The HIV infection related factor was not using condom in sexual contact. Keywords: HIV, female massage therapists, Quang Ngai

STUDYING OF CHILDREN WITH MENTAL RETARDATION IN HUE CITY IN 2011

2012 ◽  
pp. 83-87
Author(s):  
Thi Minh Xuan Doan ◽  
Xuan Chuong Tran
Keyword(s):  
Mental Retardation ◽  
Cross Sectional Study ◽  
Learning Ability ◽  
Daily Activities ◽  
Sectional Study ◽  
Cross Sectional ◽  
Slow Development ◽  
Study Results

Children with mental retardation have low intelligence, slow thinking, low learning ability in comparison with the same age children. Objectives: 1. To determine the prevalence of children with mental retardation in Hue City. 2. To study some characteristics of children with mental retardation. Materials and methodes: All children with mental retardation in Hue city. Cross sectional study. Results: The prevalence of children with mental retardation (CMR) among children under 15 yrs is 0.23%, among disable children 38.16%. The highest prevalences ware in Phu Binh, Xuan Phu quarters (0.79 and 0.66%), lowest in Thuan Loc, Thuan Thanh quarters (0.03 and 0.06%). Children over 5 yrs old were 75.95%. Most of children have slow development in movement and daily activities. More than 78% have late walking, 84% have late speaking. Conclusions: The prevalence of children with mental retardation among children under 15 yrs is 0.23%, among disable children 38.16%. Most of children have slow development in movement and daily activities.

scholarly journals Comprehensive Parameters Identification and Dynamic Model Validation of Interior-Mount Line-Start Permanent Magnet Synchronous Motors

Machines ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 4 ◽  
Author(s):  
Luqman S. Maraaba ◽  
Zakariya M. Al-Hamouz ◽  
Abdulaziz S. Milhem ◽  
Ssennoga Twaha
Keyword(s):  
Mathematical Model ◽  
Permanent Magnet ◽  
High Efficiency ◽  
Experimental Tests ◽  
Induction Machines ◽  
Test Methods ◽  
Operating Conditions ◽  
Test Method ◽  
Permanent Magnet Synchronous Motors ◽  
Synchronous Motors

The application of line-start permanent magnet synchronous motors (LSPMSMs) is rapidly spreading due to their advantages of high efficiency, high operational power factor, being self-starting, rendering them as highly needed in many applications in recent years. Although there have been standard methods for the identification of parameters of synchronous and induction machines, most of them do not apply to LSPMSMs. This paper presents a study and analysis of different parameter identification methods for interior mount LSPMSM. Experimental tests have been performed in the laboratory on a 1-hp interior mount LSPMSM. The measurements have been validated by investigating the performance of the machine under different operating conditions using a developed qd0 mathematical model and an experimental setup. The dynamic and steady-state performance analyses have been performed using the determined parameters. It is found that the experimental results are close to the mathematical model results, confirming the accuracy of the studied test methods. Therefore, the output of this study will help in selecting the proper test method for LSPMSM.

scholarly journals A Numerical Investigation into the PAT Hydrodynamic Response to Impeller Rotational Speed Variation

2021 ◽  
Vol 13 (14) ◽  
pp. 7998
Author(s):  
Maxime Binama ◽  
Kan Kan ◽  
Hui-Xiang Chen ◽  
Yuan Zheng ◽  
Daqing Zhou ◽  
...  
Keyword(s):  
Rotational Speed ◽  
Distribution Systems ◽  
Water Distribution ◽  
Production Efficiency ◽  
Operating Conditions ◽  
Energy Regulation ◽  
Speed Increase ◽  
Energy Field ◽  
Long Run ◽  
Study Results

The utilization of pump as turbines (PATs) within water distribution systems for energy regulation and hydroelectricity generation purposes has increasingly attracted the energy field players’ attention. However, its power production efficiency still faces difficulties due to PAT’s lack of flow control ability in such dynamic systems. This has eventually led to the introduction of the so-called “variable operating strategy” or VOS, where the impeller rotational speed may be controlled to satisfy the system-required flow conditions. Taking from these grounds, this study numerically investigates PAT eventual flow structures formation mechanism, especially when subjected to varying impeller rotational speed. CFD-backed numerical simulations were conducted on PAT flow under four operating conditions (1.00 QBEP, 0.82 QBEP, 0.74 QBEP, and 0.55 QBEP), considering five impeller rotational speeds (110 rpm, 130 rpm, 150 rpm, 170 rpm, and 190 rpm). Study results have shown that both PAT’s flow and pressure fields deteriorate with the machine influx decrease, where the impeller rotational speed increase is found to alleviate PAT pressure pulsation levels under high-flow operating conditions, while it worsens them under part-load conditions. This study’s results add value to a thorough understanding of PAT flow dynamics, which, in a long run, contributes to the solution of the so-far existent technical issues.

scholarly journals Indirect Health Effects of COVID-19: Unhealthy Lifestyle Behaviors during the Lockdown in the United Arab Emirates

2021 ◽  
Vol 18 (4) ◽  
pp. 1964
Author(s):  
Hadia Radwan ◽  
Mahra Al Kitbi ◽  
Hayder Hasan ◽  
Marwa Al Hilali ◽  
Nada Abbas ◽  
...  
Keyword(s):  
Physical Activity ◽  
United Arab Emirates ◽  
Lifestyle Change ◽  
Change Score ◽  
Lifestyle Changes ◽  
Lifestyle Behaviors ◽  
Negative Consequences ◽  
Unhealthy Lifestyle ◽  
Cross Sectional ◽  
Study Results

Background: Lockdown measures were implemented in many countries to limit the spread of the COVID-19 pandemic. However, such restrictions could precipitate unintended negative consequences on lifestyle behaviors. The main objective of this study was to investigate the prevalence and determinants of unhealthy behavior changes during the COVID-19 lockdown among residents of the United Arab Emirates (UAE). Methods: A cross-sectional web-based survey of adults residing in the UAE was carried out during lockdown (n = 2060). Using a multi-component questionnaire, the collected data included questions regarding the following lifestyle changes: Increased dietary intake, increased weight, decreased physical activity, decreased sleep, and increased smoking. An unhealthy lifestyle change score was calculated based on the number of unhealthy lifestyle changes each participant reported. In addition, sociodemographic and living conditions information was collected. Descriptive statistics as well as simple and multiple linear regression analyses were used to examine the prevalence and determinants of the unhealthy lifestyle changes considered in this study. Results: Among the unhealthy lifestyle changes examined, increased food intake was the most common (31.8%), followed by decreased physical activity (30%), increased weight (29.4%), decreased sleep (20.8%), and increased smoking (21%). In addition to identifying the correlates of each of the aforementioned lifestyle changes, the results of the multiple regression linear analyses revealed the following correlates for the overall unhealthy lifestyle change score: females (β = 0.32, CI: 0.22; 0.42), living in an apartment (β = 0.12, CI: 0.003; 0.23) and being overweight/obese (β = 0.24, CI: 0.15; 0.32) had higher scores, while older adults (>40 years) had lower scores (β = −0.23, CI: −0.34; −0.12). Conclusions: The COVID-19 lockdown has resulted in a high prevalence of unhealthy lifestyle behaviors and practices among UAE residents. The findings of this study provided the evidence base for officials to design interventions targeting high-risk groups and aiming to improve healthy lifestyle factors among residents during the pandemic.

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