A Parametric Study on Interlaminar Shear Strains in Cord-Rubber Composites

1984 ◽  
Vol 57 (1) ◽  
pp. 168-183 ◽  
Author(s):  
J. DeEskinazi ◽  
R. J. Cembrola
Keyword(s):  
Shear Strain ◽  
Relative Motion ◽  
Strong Influence ◽  
Design Parameters ◽  
Cross Sectional ◽  
Design Variables ◽  
Study Results ◽  
Shear Strains ◽  
Interlaminar Shear ◽  
Belt Width

Abstract The effect of different design variables used in the construction of tire belts on the interply shear phenomenon was studied using a simple, belted cylinder structure. Only balanced belt constructions were considered. The finite element method was used in the analysis of the belted structure. Predicted results were verified by performing experiments with selected combinations of the design parameters studied. Predicted and experimental results indicate the presence of interply shear strains in the cross-sectional plane of the belts; however, due to difficulties involved in measuring these strains experimentally, they have not been treated in this study. Results for shear strains in the circumferential planes only have been presented. Results for the interply shear strains at the belt edge indicate that the belt cord angle has a very strong influence on the interply shear phenomenon. It was shown that the shape of the curve depicting the relationship between cord angle and interply shear strains is influenced by other design variables of the belt as well as properties of adjacent plies, such as the bladder used to simulate a radial tire carcass ply. Interply shear strains decrease with increasing thickness between the plies and modulus of the interply rubber. In the case of a stiffer rubber, the reduction in shear strain is entirely due to a reduction in the relative motion between the belts. However, in the case of an increased interply thickness, which is accompanied by an increase in relative motion between the belts, the reduction in shear is the result of the relative motion being distributed over a larger thickness. Increasing the belt cord modulus results in an increase in interply shear strains for relatively low values of the modulus. However, beyond a certain value, approximately the modulus of fiberglass cords, increasing the cord modulus does not significantly affect interply shear strains. The shear strain-belt width relationship is strongly influenced by the cord angle used in the belts. Depending on the value of the latter, the shear strain can be a decreasing function of belt width or remain relatively constant as belt width is varied. The degree of localization of the interply shear phenomenon at the belt edge was also studied. All of the variables considered in this study, with the exception of the cord modulus, seem to affect the distribution of the shear strain along the width of the belt to varying extents. The belt width seems to have a strong influence, with wider belts resulting in significant shear strains confined to the vicinity of the belt edge.

Design of composite helicopter rotor blades to meet given cross-sectional properties

2005 ◽  
Vol 109 (1100) ◽  
pp. 471-475 ◽  
Author(s):  
S. L. Lemanski ◽  
P. M. Weaver ◽  
G. F. J. Hill
Keyword(s):  
Finite Element ◽  
Objective Function ◽  
Helicopter Rotor ◽  
Design Parameters ◽  
Stochastic Methods ◽  
Element Analysis ◽  
Cross Sectional ◽  
Design Variables ◽  
Non Linear ◽  
Optimisation Methods

Abstract This paper examines the design of a composite helicopter rotor blade to meet given cross-sectional properties. As with many real-world problems, the choice of objective and design variables can lead to a problem with a non-linear and/or non-convex objective function, which would require the use of stochastic optimisation methods to find an optimum. Since the objective function is evaluated from the results of a finite element analysis of the cross section, the computational expense of using stochastic methods would be prohibitive. It is shown that by choosing appropriate simplified design variables, the problem becomes convex with respect to those design variables. This allows deterministic optimisation methods to be used, which is considerably more computationally efficient than stochastic methods. It is also shown that the design variables can be chosen such that the response of each individual cross-sectional property can be closely modelled by a linear approximation, even though the response of a single objective function to many design parameters is non-linear. The design problem may therefore be reformulated into a number of simultaneous linear equations that are easily solved by matrix methods, thus allowing an optimum to be located with the minimum number of computationally expensive finite element analyses.

scholarly journals Quantitative comparison of 2D and 3D shock control bumps for drag reduction on transonic wings

2018 ◽  
Vol 233 (7) ◽  
pp. 2344-2359
Author(s):  
Feng Deng ◽  
Ning Qin
Keyword(s):  
Aspect Ratio ◽  
Incident Angle ◽  
Design Parameters ◽  
Comparative Performance ◽  
Cross Sectional ◽  
Shock Control ◽  
Design Variables ◽  
Natural Laminar Flow ◽  
Area Rule ◽  
2D And 3D

In this paper, the design spaces of the 2D and 3D shock control bumps on an infinite unswept natural laminar flow wing are investigated by adopting an optimization enhanced parametric study method. The design space spanned by the design variables are explored through a series of design optimization and their landscapes around the optima are revealed. The effects of the bump spacing, bump length, and Mach number are investigated respectively around the optima. The maximum cross-sectional area, bump incident angle, and aspect ratio are found to be important design parameters. The associated flow physics is discussed in relation to these parameters. The comparative performance of the 2D and 3D bumps are explained in the context of the transonic area rule. Two types of flow separation are identified by varying the bump aspect ratio at off-design conditions. It is concluded that the 2D and 3D shock control bumps can have nearly the same performances at optimal designs with similar cross-sectional areas. Some practical design principles and guidelines are suggested.

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

A Simple Model for Cornering and Belt-edge Separation in Radial Tires

1986 ◽  
Vol 14 (1) ◽  
pp. 3-32 ◽  
Author(s):  
P. Popper ◽  
C. Miller ◽  
D. L. Filkin ◽  
W. J. Schaffers
Keyword(s):  
Simple Model ◽  
Transverse Shear ◽  
Mathematical Analysis ◽  
Pure Bending ◽  
Radial Tire ◽  
Optimum Angle ◽  
Shear Strains ◽  
Interlaminar Shear ◽  
Edge Separation ◽  
Shear Bending

Abstract A mathematical analysis of radial tire cornering was performed to predict tire deflections and belt-edge separation strains. The model includes the effects of pure bending, transverse shear bending, lateral restraint of the carcass on the belt, and shear displacements between belt and carcass. It also provides a description of the key mechanisms that act during cornering. The inputs include belt and carcass cord properties, cord angle, pressure, rubber properties, and cornering force. Outputs include cornering deflections and interlaminar shear strains. Key relations found between tire parameters and responses were the optimum angle for minimum cornering deflections and its dependence on cord modulus, and the effect of cord angle and modulus on interlaminar shear strains.

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.

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.

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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