scholarly journals Strain energy method for solving wave problems of a flexible thread

2020 ◽  
Author(s):  
A.V. Bryukvin ◽  
O.Yu. Bryukvina
Keyword(s):  
Wave Propagation ◽  
Strain Energy ◽  
Wave Perturbation ◽  
Transverse Waves ◽  
Before And After ◽  
Pass Through ◽  
Wave Problems ◽  
Strain Energy Method ◽  
Front Zone ◽  
Made In

The paper considers the behavior of a flexible deformable thread when longitudinal and transverse waves pass through it. The processes occurring in a thread during the passage of a wave perturbation through it are analyzed under the assumption that the wave front zone is limited comparing with the length of the thread but not assuming this quantity to be of infinite smallness. In contrast to other similar works, no assumptions were made in advance about the shape of the thread in the zone of the wave perturbation passage (the fracture of the thread) and the dependence of the tension force on its elongation. The only requirement is the implementation of the general theorems of dynamics. Formulas for the relation of the thread speed before and after the passage of the wave with a change in the angle of thread inclination are obtained making possible solving wave propagation problems in a new way. The method is illustrated by new solutions to known problems, which allows comparing the obtained results with known solutions and verifying the advantages of the proposed method.

Infrastructure Sustainability

2011 ◽  
pp. 186-201
Author(s):  
Hoi Wai Shih ◽  
David Thambiratnam ◽  
Tommy Chan
Keyword(s):  
Energy Method ◽  
Strain Energy ◽  
Health State ◽  
Modal Strain Energy ◽  
Structural Health ◽  
Modal Strain Energy Method ◽  
Modal Flexibility ◽  
Before And After ◽  
Composite Bridges ◽  
Strain Energy Method

Assessing the structural health state of urban infrastructure is crucial in terms of infrastructure sustainability. This chapter uses dynamic computer simulation techniques to apply a procedure using vibration-based methods for damage assessment in multiple-girder composite bridges. In addition to changes in natural frequencies, this multi-criteria procedure incorporates two methods, namely, the modal flexibility and the modal strain energy method. Using the numerically simulated modal data obtained through finite element analysis software, algorithms based on modal flexibility and modal strain energy change, before and after damage, are obtained and used as the indices for the assessment of structural health state. The feasibility and capability of the approach is demonstrated through numerical studies of a proposed structure with six damage scenarios. It is concluded that the modal strain energy method is capable of application to multiple-girder composite bridges, as evidenced through the example treated in this chapter.

Nondestructive Damage Detection of Two Dimensional Plate Structures Using Modal Strain Energy Method

2008 ◽  
Vol 24 (4) ◽  
pp. 319-332 ◽  
Author(s):  
H.-W. Hu ◽  
C.-B. Wu
Keyword(s):  
Energy Method ◽  
Strain Energy ◽  
Damage Index ◽  
Mode Shapes ◽  
Two Dimensional ◽  
Plate Structures ◽  
Modal Strain Energy ◽  
Modal Strain Energy Method ◽  
Before And After ◽  
Strain Energy Method

AbstractA nondestructive detection method of surface cracks in two dimensional plate structures using modal strain energy method is investigated in this paper. Experimental modal analysis (EMA) is conducted on an aluminum alloy 6061 thin plate to obtain the mode shapes before and after damage under a completely free boundary condition. The measured mode shapes are used to compute the strain energy of the plate. Limited by the measured points, a differential quadrature method is employed to compute the partial differential terms in strain energy formula. A damage index is then defined based on strain energy ratio of the plate before and after damage. This damage index is employed to identify the location of surface crack in plate structure. A finite element analysis (FEA) is also performed to access this approach and demonstrate a feasible process for the experimental work. Good correlation between FEA and EMA results is obtained. The damage index obtained from both FEA and EMA successfully identify the location of surface crack in the aluminum plate. Only few measured mode shapes of the plate are required in this method, which provides a quick, flexible, inexpensive and nondestructive technique to identify the damagein local and global 2D plate structures.

1989 göçü sonrası Bulgaristan göçmenlerinin yemek kültüründeki değişim

2017 ◽  
Vol 4 (2) ◽  
pp. 227-245
Author(s):  
Cahit Kahraman ◽  
İlhan Güneş ◽  
Nanae Kahraman
Keyword(s):  
Eating Habits ◽  
Supply And Demand ◽  
Food Culture ◽  
Rapid Progress ◽  
Canned Food ◽  
Product Range ◽  
The World ◽  
Before And After ◽  
Day By Day ◽  
Made In

1989 göçü öncesi, dünyada eşzamanlı olarak gittikçe gelişen ve zenginleşen mutfak kültürü, Bulgaristan Türklerini de etkilemiştir. Pazardaki çeşitlilik arttıkça, yemek alışkanlıkları da değişime uğramıştır. Büyük göçten sadece 30-40 sene evvel kısıtlı imkânlar ile sınırlı sayıda yemek çeşidi üretilirken, alım gücünün artmasıyla yemek kültüründe de hızlı gelişmeler olmuştur. Artan ürün çeşitliliği yemeklere de yansımış, farklı lezzetler mutfaklara girmiştir. Göçmen yemekleri denilince hamur işleri, börek ve pideler akla gelir. Ayrıca, göçmenlerin çok zengin turşu, komposto ve konserve kültürüne sahip oldukları da bilinir. Bu çalışma, 1989 öncesi Bulgaristan’ın farklı bölgelerinde yaşayan Türklerin yemek alışkanlıklarına ışık tutmakla birlikte, göç sonrasında göçmen mutfak kültüründe bir değişiklik oluşup oluşmadığını konu almaktadır. Bu amaçla, 1989 yılında Türkiye’ye göç etmiş 50 kişiye 8 sorudan oluşan anket düzenlenmiştir. Bu verilerden yola çıkarak oluşan bulgular derlenmiş ve yeni tespitler yapılmıştır. Ayrıca, Türkiye’nin farklı bölgelerine yerleşen göçmenler, kendi göçmen pazarlarını kurmuşlardır. Bulgaristan’dan getirilen ürünlerin bu pazarlarda satılması böyle bir arz talebin hala devam ettiğine işaret etmektedir.ABSTRACT IN ENGLISHThe Diversity in Cuisine Culture of the Immigrants from Bulgaria After 1989 MigrationThe Cuisine culture that has been developing and getting rich day by day contemporaneously in the world before 1989 migration has also had an impact on Bulgarian Turks. By the increase in diversity in the market, eating habits have changed. While producing a limited number of food types with limited opportunities just some 30 or 40 years before the ‘Big Migration’, there has been a rapid progress in food culture by the help of the increase in purchase power. Enhancing product range has been reflected in food, and different tastes have entered the cuisines. When we say immigrant, the first things that come to our mind are pastry, flan and pitta bread. Moreover, it is also known that immigrants have a very rich cuisine culture of pickle, stewed fruit, and canned food. This study aims both to disclose the eating habits of Turks living in different regions of Bulgaria before 1989 and to determine whether there has been a difference in immigrant cuisine culture before and after the migration. For this purpose, a questionnaire consisting of 8 questions has been administered to 50 people who migrated to Turkey in 1989. The results gathered from these data have been compiled and new determinations have been made. In addition, immigrants that settled in different regions of Turkey have set their own immigrant markets. The fact that the products brought from Bulgaria are being sold in these markets shows that this kind of supply and demand still continues.

South Asian Developmental Crisis (Review Article)

1973 ◽  
Vol 12 (2) ◽  
pp. 181-188
Author(s):  
Rafiq Ahmad
Keyword(s):  
Second World War ◽  
World War ◽  
The Past ◽  
The Great Depression ◽  
Political Independence ◽  
Integrated Theory ◽  
Pass Through ◽  
Developed World ◽  
Second World ◽  
Made In

Like nations and civilizations, sciences also pass through period of crises when established theories are overthrown by the unpredictable behaviour of events. Economics is passing through such a crisis. The challenge thrown by the Great Depression of early 1930s took a decade before Keynes re-established the supremacy of economics. But this supremacy has again been upset by the crisis of poverty in the vast under-developed world which attained political independence after the Second World War. Poverty had always existed but never before had it been of such concern to economists as during the past twenty five years or so. Economic literature dealing with this problem has piled up but so have the agonies of poverty. No plausible and well-integrated theory of economic development or under-development has emerged so far, though brilliant advances have been made in isolated directions.

Coronary Care in a General Hospital

1971 ◽  
Vol 16 (3) ◽  
pp. 173-182 ◽  
Author(s):  
Gavin Shaw ◽  
Bernard Groden ◽  
Evelyn Hastings
Keyword(s):  
Myocardial Infarction ◽  
Intensive Care Unit ◽  
Intensive Care ◽  
General Hospital ◽  
First Year ◽  
Duration Of Stay ◽  
Before And After ◽  
The Mean ◽  
Coronary Care ◽  
Made In

The establishment, staffing and structure and observations made in the first year of the existence of coronary care in an intensive care unit in a general hospital are recorded. Two hundred and twenty eight patients were admitted during the year in whom the diagnosis of myocardial infarction was confirmed. There were 29 deaths in the unit and 14 deaths occurred in the wards of the hospital after discharge from the unit. 49.1 per cent of the patients were admitted within 4 hours of the onset of symptoms and the mean duration of stay in the unit was 86.5 hours. The type of arrhythmia detected in the unit, and the treatment given to the patients both before and after admission to the intensive care unit are described.

Botzinger complex region role in phrenic-to-phrenic inhibitory reflex of cat

1989 ◽  
Vol 67 (4) ◽  
pp. 1364-1370 ◽  
Author(s):  
D. F. Speck
Keyword(s):  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Inhibitory Response ◽  
Phrenic Nerve Stimulation ◽  
Bötzinger Complex ◽  
Before And After ◽  
Pass Through ◽  
Bilateral Lesions ◽  
Decerebrate Cats ◽  
Inhibitory Reflex

Neuronal recordings, microstimulation, and electrolytic and chemical lesions were used to examine the involvement of the Botzinger Complex (BotC) in the bilateral phrenic-to-phrenic inhibitory reflex. Experiments were conducted in decerebrate cats that were paralyzed, ventilated, thoracotomized, and vagotomized. Microelectrode recordings within the BotC region revealed that some neurons were activated by phrenic nerve stimulation (15 of 69 expiratory units, 9 of 67 inspiratory units, and 19 nonrespiratory-modulated units) at average latencies similar to the onset latency of the phrenic-to-phrenic inhibition. In addition, microstimulation within the BotC caused a short latency transient inhibition of phrenic motor activity. In 17 cats phrenic neurogram responses to threshold and supramaximal (15 mA) stimulation of phrenic nerve afferents were recorded before and after electrolytic BotC lesions. In 15 animals the inhibitory reflex was attenuated by bilateral lesions. Because lesion of either BotC neurons or axons of passage could account for this attenuation, in eight experiments the phrenic-to-phrenic inhibitory responses were recorded before and after bilateral injections of 5 microM kainic acid (30–150 nl) into the BotC. After chemical lesions, the inhibitory response to phrenic nerve stimulation remained; however, neuronal activity typical of the BotC could not be located. These results suggest that axons important in producing the phrenic-to-phrenic reflex pass through the region of the BotC, but that BotC neurons themselves are not necessary for this reflex.

The Behaviour of Multiple Loops in Torsion

1988 ◽  
Vol 15 (3) ◽  
pp. 149-156 ◽  
Author(s):  
R. A. Cavina ◽  
N. E. Waters
Keyword(s):  
Energy Method ◽  
Strain Energy ◽  
Vertical Axis ◽  
Experimental Measurements ◽  
Complementary Strain ◽  
Radial Axis ◽  
Strain Energy Method ◽  
Good Agreement

The angular stiffness of a multiple looped span, subject to rotation about a vertical axis (torsion) and also to rotation about a horizontal or radial axis (mesio-distal tilt), have been derived using the complementary (strain) energy method. Experimental measurements on enlarged models were in good agreement with the values calculated from the theoretical relationships obtained. The variations in angular stiffness resulting from changes in the loop height, width, and position of clinical sized loops are discussed.

SERIAL ESTIMATION OF PLASMA RENIN CONCENTRATION DURING PREGNANCY AND AFTER PARTURITION

1966 ◽  
Vol 35 (4) ◽  
pp. 373-378 ◽  
Author(s):  
J. J. BROWN ◽  
D. L. DAVIES ◽  
P. B. DOAK ◽  
A. F. LEVER ◽  
J. I. S. ROBERTSON
Keyword(s):  
Pregnant Women ◽  
Plasma Renin ◽  
Plasma Renin Concentration ◽  
Before And After ◽  
Normal Women ◽  
Made In

SUMMARY Plasma renin concentration has been measured in normal women at intervals throughout pregnancy. Further measurements have been made in the days and hours before and after delivery of the foetus and placenta. Plasma renin was consistently raised in the majority of pregnant women and did not change markedly until 24 hr. or more after delivery. The significance of these findings is discussed.

GUIDANCE IN MATERNAL AND INFANT CARE TWO MONTHS BEFORE AND AFTER THE BIRTH OF THE FIRST-BORN

PEDIATRICS ◽  
1948 ◽  
Vol 2 (2) ◽  
pp. 200-206
Author(s):  
AUGUSTA STUART CLAY
Keyword(s):  
Normal Growth ◽  
Point Of View ◽  
High School Education ◽  
Pediatric Care ◽  
New Haven ◽  
Private Physician ◽  
Healthy Pregnancy ◽  
Before And After ◽  
Haven Hospital ◽  
Made In

THIS study was made in the belief that family living and growth can be healthier if parents understand how mother and baby develop and what they need. Eleven mothers were visited weekly for two months before and after the birth of their firstborn to discover what guidance they wanted, what was offered, and what additional guidance was needed. The writer secured their cooperation by agreeing to work with them as a consultant, to interpret their point of view to the doctor, to explain medical instructions when permitted, and to teach the normal growth processes of mother and baby. Ten mothers were registered in the prenatal clinics of the New Haven Hospital; the eleventh had a private physician. They had no recorded problems beyond the needs of healthy pregnancy and they wanted to participate. Eight husbands agreed to take part in the study. The other three were overseas, but their wives reported for them. Backgrounds varied; 20 of the 22 had had college or high school education; all were between 18 and 32. None dropped out, and after the four months all asked for continued guidance. Cases were too few and the study too brief for statistical evidence. But problems were uncovered which needed to be considered and which have largely been neglected in routine obstetric and pediatric care. These parents wanted to learn—not in classes, but in the privacy of home—how to care for mother and baby without disrupting their accustomed way of living. All wanted the care and interest of one doctor for mother and one for baby. However, six women and five men preferred to talk with a consultant who was not a doctor, but who was affiliated with their doctors. The doctors seemed too busy for "little things" and "family affairs," and they saw so many doctors that they all seemed strangers. Once they felt sure that the consultant's interest was in themselves rather than in teaching them, they set the pace and pattern in the conference. There was no questionnaire, no probing, no set procedure. If they had any immediate interests or problems: job, move, presents, trips, in-laws, illness—these were discussed before they talked of pregnancy and baby.

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