The Performance of Sailing Yachts in Oblique Seas

1974 ◽  
Vol 11 (04) ◽  
pp. 383-392
Author(s):  
David R. Pedrick

The difference in the effects of rough water on similar sailing yachts has been one of the intriguing puzzles that sailors, designers, and researchers have long tried to understand. It is not uncommon for two yachts of equal performance in smooth-sea conditions to have their speed or pointing ability reduced by different amounts when encountering waves. To investigate the causes of such behavior, it is important to have a rational procedure to analyze how changes in hull form, weight distribution, rig, and other design features affect the speed and motions of sailing yachts. This paper discusses the relationship of wind to rough water and of motions and added resistance to wave length and height. It then describes a procedure to predict motions, sailing speed, and speed-made-good to windward in realistic windward sailing conditions. The procedure utilizes results of heeled and yawed model tests of 12-metre yachts in oblique regular waves to predict performance in a Pierson-Moskowitz sea state corresponding closely to the equilibrium true wind speed.

1974 ◽  
Author(s):  
David R. Pedrick

Differences in the effects that rough water has on similar sailing yachts has been one of the intriguing puzzles that sailors, designers, and researchers have long tried to understand, It is not uncommon that two yachts whose performance is equal in smooth sea conditions will have their speed or point­ing ability reduced by different amounts when encountering waves, To investigate the causes of such behavior, it is important to have a rational procedure to analyze how changes in hullform, weight distribution, rig, and other design features affect the speed and motions of sailing yachts. This paper discusses the relationship of wind to rough water and of motions and added resistance to wave length and height, It then describes a procedure to predict motions, sailing speed, and speed-made-good to windward in realistic windward sailing conditions, The procedure utilizes results of heeled and yawed model tests of twelve meter yachts in oblique regular waves to predict performance in a Pierson-Moskowitz sea state corresponding closely to the equilibrium true wind speed.


1991 ◽  
Author(s):  
James F. Moran

The purpose of this investigation was to determine the effect of pitch gyradius on added resistance of yacht hulls. Tank testing of a model yacht in head seas was performed in the Webb Robinson Model Basin. The model was tested in regular waves at two speeds and five variations of gyradius. The model was also evaluated in irregular seas of the Pierson-Moskowitz spectrum at various speeds with two gyradii. Response Amplitude Operators were developed from the regular wave data and comparisons made. The irregular wave data were analyzed for the effect of speed on the difference in added resistance between the maximum and minimum gyradius settings. Several conclusions were arrived at after analyzing the data. The Response Amplitude Operaters shift as the gyradius changes. In regular waves, at low frequencies of encounter, a lower, gyradius resulted in less added frequencies of encounter in regular waves, this trend reverses itself and the higher gyradii result in reduced added resistance. However, at higher frequencies of encounter in regular waves, this trend reverses, reverses itself in reduced added resistance. The peaks of the RAO curves shift to higher frequencies at higher gyradii. It was also concluded that at the higher speed, Froude Number of 0.3, the added resistance was lower relative to the still-water resistance for each gyradius tested. The irregular wave testing revealed the effect of the lower frequencies dominating the irregular wave spectrum. The minimum gyradius, in irregular seas showed less added resistance than the maximum gyradius. In addition, the irregular wave testing verified, the reduction of added resistance, relative to still-water resistance, at increasing speeds for both the minimum and maximum gyradii.


2021 ◽  
Vol 10 (1) ◽  
pp. 1-12
Author(s):  
Noviana Norrohmat ◽  
Umar Nimran ◽  
Kusdi Raharjo ◽  
Hamidah Nayati Utami ◽  
Endang Siti Astuti

The purpose of this research is to determine the organizational support for professionalism that has never been done before. The research approach is to conceptualize the structure of the relationship of variables from a study. Verification research is to test the hypothesis through data collection in the field using two methods, namely descriptive survey and explanatory survey. The use of both methods aims to analyze the causality relationship between research variables in accordance with the hypothesis quantitatively. There is significant influence between the variables of organizational support to professional variables. However, different results are found on the influence of organizational support variables on OCB and performance that have no significant effect. There is also an indirect influence between organizational support variables on OCB and performance through intermediary intervening professionalism variables. The difference between this research and the previous research are the use of constructs and the measurement in the unit of analysis being used.


2017 ◽  
Vol 13 (23) ◽  
pp. 234
Author(s):  
Pascal Dieudonné Roy-Ema

For over sixty years (from 1910 to 1973), Martin Heidegger carried out a work of thought which led him to create a large quantity of neologisms. It also led him to create a new use of idioms in the German language. This was regarded as a renewed vocabulary. His study bears new meanings and expresses the philosopher's work of thought and the new concepts he proposes. Among them is the Ereignis that this text proposes to question the content. The Ereignis is what makes time and being belongs to each other. It is the relationship of all the relations engendered by this co-membership. This is made possible by the difference installed at the heart of the same. Heidegger himself admitted that the Ereignis was the keyword of his whole thought since the early 1930s. It is the word-director of his thought.


2020 ◽  
Vol 1 (9) ◽  
pp. 8-12
Author(s):  
Inna Zelenko ◽  

The article reflects the diversity of views on the concept of "legal axiom". It is clarified that there are lawyers who deny the existence of the concept of "axiom" in law. It is presented that some scholars identify legal axioms with legal customs in terms of content, formulation and existence, as well as methods of provision. It is revealed that legal axioms have common features and differences with legal presumptions. It is emphasized that the legal presumption and legal axiom are understood as true without evidence. It is considered that the difference between a legal presumption and a legal axiom lies in the difference of circumstances: they allow to consider them plausible; possibilities (impossibilities) of refutation; significance, content and form It is demonstrated that there are several approaches to the relationship of legal axioms with the principles of law. It has been found that the first group of scholars identify the principles of law and axioms. Attention is drawn to the fact that the second group of scholars notes that axioms are prerequisites for the principles of law. It is presented that the representatives of the third group distinguish between the concepts of principles of law and legal axioms. It has been shown that the complex interrelationships of principles and axioms are reflected in their dialectical unity, their ability to pass from one to another, and the disclosure of one phenomenon through another. It is noted that axioms are subject to change, so axioms and presumptions are closely interrelated and under certain conditions can replace each other. The definition of legal axioms has been further considered. Legal axioms are a multifaceted complex phenomenon of legal reality related to law, legal awareness and legal science. regularities, properties of special legal principles of law and serve to simplify legal regulation.


1990 ◽  
Vol 73 (6) ◽  
pp. 859-863 ◽  
Author(s):  
Robert D. Brown ◽  
David O. Wiebers ◽  
Glenn S. Forbes

✓ Among 91 patients with unruptured intracranial arteriovenous malformations (AVM's), 16 patients had 26 unruptured intracranial saccular aneurysms. An actuarial analysis showed the risk of intracranial hemorrhage among patients with coexisting aneurysm and AVM to be 7% per year at 5 years following diagnosis compared to 1.7% for patients with AVM alone. The difference in length of survival free of hemorrhage was significant (log-rank, p < 0.0007). Several angiographic and clinical parameters were investigated to better understand the relationship of these lesions. The aneurysms occurred in similar percentages in patients with small, medium, and large AVM's. Twenty-five aneurysms were on arteries feeding the malformation system, almost equally distributed proximally and distally. Eleven aneurysms were atypical in location, and all arose from primary or secondary branch feeders to the malformation; 24 were on enlarged feeding arteries. Eleven (16%) of the 67 patients with high-flow AVM's had associated aneurysms, compared with five (21%) of the 24 patients with low-flow AVM's. Four (16%) of 25 low-shunt malformations and 12 (18%) of 65 high-shunt malformations had associated aneurysms. All five aneurysms associated with low-shunt malformations were on a direct arterial feeder of the malformation. These data suggest that the intracranial AVM's predispose to aneurysm formation within AVM feeding systems and that the mechanism is not simply based upon the high blood flow or high arteriovenous shunt in these systems.


2021 ◽  
pp. 1-10
Author(s):  
Peña Dieste Pérez ◽  
Luis M. Esteban ◽  
Ricardo Savirón-Cornudella ◽  
Faustino R. Pérez-López ◽  
Sergio Castán-Mateo ◽  
...  

<b><i>Objective:</i></b> This study aimed to assess reduced fetal growth between 35 weeks of gestation and birth in non-small for gestational age fetuses associated with adverse perinatal outcomes (APOs). <b><i>Material and Method:</i></b> It is a retrospective cohort study of 9,164 non-small for gestational age fetuses estimated by ultrasound at 35 weeks. The difference between the birth weight percentile and the estimated percentile weight (EPW) at 35 weeks of gestation was calculated, and we studied the relationship of this difference with the appearance of APO. APOs were defined as cesarean or instrumental delivery rates for nonreassuring fetal status, 5-min Apgar score &#x3c;7, arterial cord blood pH &#x3c;7.10, and stillbirth. Fetuses that exhibited a percentile decrease between both moments were classified into 6 categories according to the amount of percentile decrease (0.01–10.0, 10.01–20.0, 20.01–30.0, 30.01–40.0, 40.01–50.0, and &#x3e;50.0 percentiles). It was evaluated whether the appearance of APO was related to the amount of this percentile decrease. Relative risk (RR) was calculated in these subgroups to predict APOs in general and for each APO in particular. Receiver operating characteristic and area under curves (AUC) for the difference in the percentile was calculated, used as a continuous parameter in the entire study population. <b><i>Results:</i></b> The median gestational age at delivery in uncomplicated pregnancies was 40.0 (39.1–40.7) and in pregnancies with APOs 40.3 (49.4–41.0), <i>p</i> &#x3c; 0.001. The prevalence of APOs was greater in the group of fetuses with a decrease in percentile (7.6%) compared to those with increased percentile (4.8%) (<i>p</i> &#x3c; 0.001). The RR was 1.63 (95% CI: 1.365–1.944, <i>p</i> &#x3c; 0.001). Although the differences were significant in all decreased percentile groups, RRs were significantly higher when decreased growth values were &#x3e;40 points (RR: 2.036, 95% CI: 1.581–2.623, <i>p</i> &#x3c; 0.001). The estimated value of the AUC for percentile decrease was 0.58 (0.56–0.61, <i>p</i> &#x3c; 0.001). <b><i>Conclusion:</i></b> Fetuses with a decrease in the EPW between the ultrasound at 35 weeks of gestation and birth have a higher risk of APOs, being double in fetuses with a decrease of &#x3e;40 percentile points.


2021 ◽  
pp. 37-47
Author(s):  
BORIS KORDIĆ

The problems of relations of authority and power, authority and violence, authority and security in today's world point to the need to continually write about and discuss the authority. The paper proceeds from the ontological understanding of authority as a voluntary activity that is done because the actor believes the other person will watch their activity with approval. After that the results of research on the relationship of authority and obedience are problematized, and the question is raised about reasons for rejecting obedience. The difference of internal and external authorities is introduced and then analysed the emergence and development of the internal authority according to psychoanalytic theories. It turns out that the internal authority is attached to the inner true being of man and is based on caring for other people. Development of internal authority can set us free of coercion of outside authorities and help in coping and fight against human destructiveness.


2021 ◽  
Vol 98 (6) ◽  
pp. 36-42
Author(s):  
A.V. TURKOV ◽  
◽  
S.I. POLESHKO ◽  
E.A. FINADEEVA ◽  
K.V. MARFIN ◽  
...  

The relationship between the maximum deflections from a static uniformly distributed load W0 and the fundamental frequency of natural transverse vibrations of a round isotropic plate of linearly variable thickness with thickening to the edge under homogeneous conditions of support along the outer contour, depending on the ratio of the thickness of the plate in the center to the thickness along the edge, is considered. According to the results of the study, graphs of the dependence of the maximum deflection and the frequency of natural vibrations of the plate on the ratio t1 / t2 are constructed. It is shown that for round plates of linearly variable thickness at t1/t2<1.1 coefficient K with an accuracy of 5.9% coincides with the analytical coefficient for round plates of constant thickness. Numerical studies shows that when the ratio of the thicknesses on the contour and in the center is equal to two, the difference in the coefficient K, which depends on the relationship between the static and dynamic characteristics of the platinum, is about 25% for hinged support along the contour and up to 37% for rigid support. This indicates a more significant effect of uneven mass distribution for such boundary conditions.


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