scholarly journals RESONANCE CONDITIONS IN N°.l DOCK OF LUANDA HARBOUR

1964 ◽  
Vol 1 (9) ◽  
pp. 48
Author(s):  
Fernando Manzanares Abecasis
Keyword(s):  
Experimental Study ◽  
Detailed Analysis ◽  
Analytic Study ◽  
Constant Increase ◽  
Model Studies ◽  
Long Period ◽  
General Plan ◽  
Resonance Phenomena ◽  
Port Facilities ◽  
Three Stages

About 900 m of berth length arranged around a single pier are at present available in the port of Luanda. Due to the constant increase of traffic through the port, the "Brigada de Estudos do Porto de Luanda" (Brigade of Stud ies of the Luanda Harbour) decided to prepare a general plan of extension of the port facilities. The extension planned comprises the construction of a new pier, which together with the existing one will delimit a triangular dock - dock n°-.l —, and of a se ries of rectangular basins between the new dock and the area of S.Pedro da Barra fortress (fig.l). The danger of possible resonance phenomena and the fact that this problem can be dealt with before construction begins, led the Brigade to undertake a detailed analysis of it before tak ing decisions on the extension works of the port. This analysis comprised three stages: a) Observation in nature of long-period waves in Luanda bay. b) Analytic study of the behaviour of the planned docks under the action of possible long-period waves . c) Experimental study in model of the same phenomenon. The author, as consulting engineer of the Brigade of Stud ies, programmed observations a) and analysed their results,performed the analytic study b) [l] , [2] , [3] and, as head of the Hydraulic Department of Laboratorio Nacional de Engenharia Ci vil, planned, supervised and interpreted the model studies.

Experimental Study of Particle Size, Sound Velocity, and Resonance Phenomena in a Two-Phase Foam Flow

2001 ◽  
Vol 32 (4-6) ◽  
pp. 5
Author(s):  
A. P. Sevast'yanov ◽  
I. V. An ◽  
S. I. Vainshtein ◽  
Yu. A. Sevast'yanov ◽  
A. V. Sidnev ◽  
...  
Keyword(s):  
Experimental Study ◽  
Particle Size ◽  
Sound Velocity ◽  
Two Phase ◽  
Foam Flow ◽  
Resonance Phenomena

Modeling and Experimental Study of a Wire Clamp for Wire Bonding

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Fuliang Wang ◽  
Dengke Fan
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Energy Conservation ◽  
Design Process ◽  
Gold Wire ◽  
Wire Bonding ◽  
Fe Model ◽  
Amplification Ratio ◽  
Model Studies ◽  
Thermosonic Wire Bonding

A wire clamp is used to grip a gold wire with in 1–2 ms during thermosonic wire bonding. Modern wire bonders require faster and larger opening wire clamps. In order to simplify the design process and find the key parameters affecting the opening of wire clamps, a model analysis based on energy conservation was developed. The relation between geometric parameters and the amplification ratio was obtained. A finite element (FE) model was also developed in order to calculate the amplification ratio and natural frequency. Experiments were carried out in order to confirm the results of these models. Model studies show that the arm length was the major factor affecting the opening of the wire clamp.

scholarly journals LARGE SCALE MODEL TESTS OF PLACED STONE BREAKWATERS

1976 ◽  
Vol 1 (15) ◽  
pp. 147 ◽  
Author(s):  
Charles K. Sollitt ◽  
Donald H. Debok
Keyword(s):  
Large Scale ◽  
Scale Model ◽  
Small Scale ◽  
Stable Model ◽  
Model Studies ◽  
Drag Forces ◽  
Port Facilities ◽  
Large Scale Model ◽  
Wave Heights ◽  
Water Depths

Large scale model studies reveal that Reynolds scaling can affect the apparent stability and wave modifying properties of layered breakwater structures. Results of a study for a breakwater configuration designed to protect offshore power and port facilities in water depths to 60 feet are presented and discussed. The armor layer of this structure is formed from quarried rock of irregular rectangular parallelepiped shape, individually placed perpendicular to 1:2 seaward slope and crest. The resulting armor layer is relatively smooth, densely packed and very stable. Model studies of similar configurations were studied at 1:10, 1:20 and 1:100 scale ratios. Stability, runup, rundown and reflection were measured for a variety of water depths, wave heights and periods. Analysis of the large scale test results establish that the placed stone armor is approximately as stable as dolos armor units. Runup, rundown and reflection respond similar to rough, impermeable slopes. Comparison of large and small scale results demonstrate that relative increases in drag forces at lower Reynolds numbers decrease stability and runup in small scale models.

scholarly journals Gametogenesis and spawning of Spirobranchus tetraceros (Polychaeta, Serpulidae) in Abu Kir Bay, Egypt

2005 ◽  
Vol 6 (1) ◽  
pp. 89 ◽  
Author(s):  
S. A. SELIM ◽  
F. ABDEL NABY ◽  
A.A. F.A. GAB-ALLA ◽  
A. GHOBASHY
Keyword(s):  
Red Sea ◽  
Oocyte Development ◽  
Maximum Diameter ◽  
Long Period ◽  
Sperm Development ◽  
Three Stages

The serpulid polychaete Spirobranchus tetraceros of Red Sea / Indo-pacific origin, recently has succeeded to establish a foothold in Alexandria Mediterranean waters. Worms were monthly scraped from submerged iron substrates at Abu Kir Bay during the period December 2000 – November 2001. Both light and TEM were used to study gametogenesis and time of spawning of S. tetraceros.Gametogenesis was asynchronous and oogenesis could be divided into two previtellogenic, two vitellogenic and a spawning stage. Oocyte development took about 8 months, from October to June. Spawning occurred from late May - early June until October. Thus S. tetraceros is a long period spawner. The maximum diameter of ripe oocyte is 78 mm. The spermatogenic phase could be divided into three stages: spermatogonia, spermatocytes and spermatids (including spermatozoa). The duration of sperm development took about 8 months. Spermatocytes persist from October to March. By March the sperms grew rapidly until they became spermatozoa in May. The sperm could be considered ect-aquasperm with regard to its fertilization biology.

scholarly journals Perception of General British monophthongs

Jezikoslovlje ◽  
2019 ◽  
Vol 20 (3) ◽  
pp. 475-496
Author(s):  
Andrej Stopar
Keyword(s):  
Experimental Study ◽  
Foreign Language ◽  
Explicit Instruction ◽  
Vowel Systems ◽  
Three Stages

The paper presents an experimental study on the perception of the Gen-eral British monophthongs that was conducted in three stages in 2014–2018. The vowels observed are studied by (i) comparing the vowel sys-tems of General British and Slovene, and (ii) by conducting an experi-ment on their perception. The analysis focuses on the participants’ over-all performance, their most frequent misperceptions, and their progress over the course of one semester. The results indicate: that the previously observed production difficulties mirror perception difficulties; that the discriminative failures of FL vowels are not entirely predictable by com-paring vowel systems; that new sound contrasts are assimilated in differ-ent ways; and that the participants’ perception of foreign language pho-nemes can benefit from explicit instruction.

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