scholarly journals A new type of sea bed waves

2001 ◽  
Vol 28 (7) ◽  
pp. 1323-1326 ◽  
Author(s):  
Michiel A. F. Knaapen ◽  
Suzanne J. M. H. Hulscher ◽  
Huib J. de Vriend ◽  
Ad Stolk
Keyword(s):  
Sea Bed ◽  
New Type ◽  
Bed Waves

scholarly journals CHANGES OP SEA BED DUE TO DETACHED BEEAKWATEES

1976 ◽  
Vol 1 (15) ◽  
pp. 91 ◽  
Author(s):  
Osamu Toyoshima
Keyword(s):  
Flood Control ◽  
Sandy Beaches ◽  
Sediment Supply ◽  
Beach Erosion ◽  
Sea Bed ◽  
Open Sea ◽  
New Type ◽  
Japanese Islands ◽  
Coastal Land ◽  
Sea Cliffs

Since most of the coast lines of Japanese Islands are faced on the open sea and are always attacked by severe waves, beach erosion is one of serious problems in the coastal engineering field. Although Japan has all types of coastal land-forms except the glacial shoreline, remarkable recessions of coast line have been observed at sea cliffs and sandy beaches. The recession of sea cliffs has been found at several districts in Japan since old times. But, beach erosion has become increasingly severe since the early 1950's. The main causes of beach erosion are the reduction in sediment supply from rivers and the interception of the longshore paths of sediment. The former is caused by the river improvement works and by the construction of dams and debris barriers or Sabo works. The later is caused by the coastal structures, such as jetties, groins, breakwaters, and flood-control outlets. In addition a new type of beach erosion has been observed at the coast where coast protection works such as seawalls and bulkheads exist. The beach erosion defence works are being executed at more than 300 sites in Japan. Considerable number of the works were commenced in the 1960's.

scholarly journals OPEN TYPE QUAY STRUCTURES UNDER PROPELLER JETS

2012 ◽  
Vol 1 (33) ◽  
pp. 19 ◽  
Author(s):  
Yalcin Yuksel ◽  
Selahattin Kayhan ◽  
Yesim Celikoglu ◽  
Kubilay Cihan
Keyword(s):  
Flow Characteristics ◽  
Structure Design ◽  
Shear Stresses ◽  
Flow Area ◽  
Open Type ◽  
Sea Bed ◽  
Cylindrical Piles ◽  
New Type ◽  
Hot Film ◽  
Bed Shear Stresses

In recent years, dramatically increases in ship dimensions and installed engine power, introduction of new type of special purpose ships and use of roll-on/roll-of, ferries, container ships can cause damage which in many cases threatens to undermine berth structures. Vessel jets of these types of ships can change flow area and cause erosion and scour around foundation of berth structures. Due to the damages in berth structures maintenance and repair cost may increase and also cause management losses. For this reason vessel jet induced the flow area around the berth structures during ships berthing and un-berthing operations are extremely important factor for the port structure design. This study is related with investigation of the flow characteristics at the sea bed around the pile, experimentally. Vessel jets were simulated both as circular wall jet and also propeller jet. The objective of this study is to determine the sea bed shear stress and velocity profiles along the jet axis for open type wharf structures (around a cylindrical piles and also on the slopes). Hot film anemometers were used to measure the magnitude of the bed shear stresses. The results from propeller jet experiments explained the erosion over the slopes. Bed shear and velocity profile measurements were carried out on the rigid bed conditions.

A New Type of Robot Used for Deep Stratum Drilling in Seabed

2020 ◽  
Author(s):  
Peihao Zhang ◽  
Jiawang Chen ◽  
Zhenwei Tian ◽  
ZiQiang Ren ◽  
Yongqiang Ge ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Mining Area ◽  
Natural Gas Hydrate ◽  
Working Process ◽  
Design Structure ◽  
Sea Bed ◽  
Oil And Gas Resources ◽  
New Type ◽  
Term Monitoring

Abstract With the increasing scale of the exploitation of ocean oil and gas resources, the decomposition of natural gas hydrate and the exploitation of submarine oil will damage the engineering mechanical structure of submarine sediments, leading to submarine collapse, landslide, even earthquake and other geological disasters, seriously threatening the exploration and exploitation of Marine resources. Therefore, it is necessary to develop a deep-seabed drilling robot to carry out real-time long-term monitoring of changes in the seabed environment by carrying sensors and detection devices. This paper will describe the design structure of the drilling robot, and explain the working process through that the drilling robot is released from the sea bed into the stratum of the mining area, and can achieve autonomous drilling and steering functions in the seabed stratum. In this paper, theoretical analysis and simulation verification will prove the feasibility of the robot moving in the stratum.

The Microstructure of Shock-Synthesized Diamond

1967 ◽  
Vol 25 ◽  
pp. 324-325
Author(s):  
Lucien F. Trueb
Keyword(s):  
Single Crystals ◽  
Preferred Orientation ◽  
High Magnification ◽  
Texture Pattern ◽  
Shock Process ◽  
New Type ◽  
Diffraction Diagram

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.

New type electron gun with electrostatic and electromagnetic lenses

1978 ◽  
Vol 36 (1) ◽  
pp. 62-63
Author(s):  
T. Ichinokawa ◽  
H. Maeda
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Optimum Condition ◽  
Bias Voltage ◽  
Electron Gun ◽  
Charge Effect ◽  
Micro Fabrication ◽  
Maximum Brightness ◽  
New Type ◽  
The Ideal

I. IntroductionThermionic electron gun with the Wehnelt grid is popularly used in the electron microscopy and electron beam micro-fabrication. It is well known that this gun could get the ideal brightness caluculated from the Lengumier and Richardson equations under the optimum condition. However, the design and ajustment to the optimum condition is not so easy. The gun has following properties with respect to the Wehnelt bias; (1) The maximum brightness is got only in the optimum bias. (2) In the larger bias than the optimum, the brightness decreases with increasing the bias voltage on account of the space charge effect. (3) In the smaller bias than the optimum, the brightness decreases with bias voltage on account of spreading of the cross over spot due to the aberrations of the electrostatic immersion lens.In the present experiment, a new type electron gun with the electrostatic and electromagnetic lens is designed, and its properties are examined experimentally.

A new type of defect structure in 124-superconducting oxide revealed by HREM

1991 ◽  
Vol 49 ◽  
pp. 1092-1093
Author(s):  
R. Sharma ◽  
B.L. Ramakrishna ◽  
N.N. Thadhani ◽  
D. Hianes ◽  
Z. Iqbal
Keyword(s):  
Shock Wave ◽  
Defect Structure ◽  
Neutron Radiation ◽  
Weak Links ◽  
Defect Structures ◽  
New Materials ◽  
New Type ◽  
Current Densities ◽  
Processing Techniques ◽  
Microstructural Studies

After materials with superconducting temperatures higher than liquid nitrogen have been prepared, more emphasis has been on increasing the current densities (Jc) of high Tc superconductors than finding new materials with higher transition temperatures. Different processing techniques i.e thin films, shock wave processing, neutron radiation etc. have been applied in order to increase Jc. Microstructural studies of compounds thus prepared have shown either a decrease in gram boundaries that act as weak-links or increase in defect structure that act as flux-pinning centers. We have studied shock wave synthesized Tl-Ba-Cu-O and shock wave processed Y-123 superconductors with somewhat different properties compared to those prepared by solid-state reaction. Here we report the defect structures observed in the shock-processed Y-124 superconductors.

ESEM - A multipurpose surface Electron Microscope

1986 ◽  
Vol 44 ◽  
pp. 632-633 ◽  
Author(s):  
G.D. Danilatos
Keyword(s):  
Electron Microscope ◽  
Room Temperature ◽  
Environmental Scanning ◽  
Gas Composition ◽  
Saturated Water Vapor ◽  
Surface Electron ◽  
Current State ◽  
Saturated Water ◽  
New Type ◽  
Temperature And Pressure

Over recent years a new type of electron microscope - the environmental scanning electron microscope (ESEM) - has been developed for the examination of specimen surfaces in the presence of gases. A detailed series of reports on the system has appeared elsewhere. A review summary of the current state and potential of the system is presented here.The gas composition, temperature and pressure can be varied in the specimen chamber of the ESEM. With air, the pressure can be up to one atmosphere (about 1000 mbar). Environments with fully saturated water vapor only at room temperature (20-30 mbar) can be easily maintained whilst liquid water or other solutions, together with uncoated specimens, can be imaged routinely during various applications.

Trial production of γ-type energy filtering TEM

1995 ◽  
Vol 53 ◽  
pp. 604-605
Author(s):  
Y. Taniguchi ◽  
E. Nakazawa ◽  
S. Taya
Keyword(s):  
Magnetic Energy ◽  
Electron Optics ◽  
Electron Microscopic ◽  
Mass Spectrometers ◽  
Ion Optics ◽  
Energy Filtering ◽  
New Information ◽  
New Type ◽  
Fringing Fields

Imaging energy filters can add new information to electron microscopic images with respect to energy-axis, so-called electron spectroscopic imaging (ESI). Recently, many good results have been reported using this imaging technique. ESI also allows high-contrast observation of unstained biological samples, becoming a trend of the field of morphology. We manufactured a new type of energy filter as a trial production. This energy filter consists of two magnets, and we call γ-filter since the trajectory of electrons shows ‘γ’-shape inside the filter. We evaluated the new energyγ-filter TEM with the γ-filter.Figure 1 shows schematic view of the electron optics of the γ-type energy filter. For the determination of the electron-optics of the γ-type energy filter, we used the TRIO (Third Order Ion Optics) program which has been developed for the design of high resolution mass spectrometers. The TRIO takes the extended fringing fields (EFF) into consideration. EFF makes it difficult to design magnetic energy filters with magnetic sector fields.

Development of imaging plate for a TEM and its characteristics

1989 ◽  
Vol 47 ◽  
pp. 100-101
Author(s):  
N. Mori ◽  
T. Oikawa ◽  
Y. Harada ◽  
J. Miyahara ◽  
T. Matsuo
Keyword(s):  
Dynamic Range ◽  
Protective Layer ◽  
High Sensitivity ◽  
Imaging Plate ◽  
Phosphor Layer ◽  
Imaging Device ◽  
X Ray Imaging ◽  
New Type ◽  
Basic Characteristics ◽  
Reading System

The Imaging Plate (IP) is a new type imaging device, which was developed for diagnostic x ray imaging. We have reported that usage of the IP for a TEM has many merits; those are high sensitivity, wide dynamic range, and good linearity. However in the previous report the reading system was prototype drum-type-scanner, and IP was also experimentally made, which phosphor layer was 50μm thick with no protective layer. So special care was needed to handle them, and they were used only to make sure the basic characteristics. In this article we report the result of newly developed reading, printing system and high resolution IP for practical use. We mainly discuss the characteristics of the IP here. (Precise performance concerned with the reader and other system are reported in the other article.)Fig.1 shows the schematic cross section of the IP. The IP consists of three parts; protective layer, phosphor layer and support.

Automatic analysis of Kikuchi diffraction patterns

1994 ◽  
Vol 52 ◽  
pp. 900-901
Author(s):  
H. Weiland ◽  
D. P. Field
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Spatial Resolution ◽  
Relevant Information ◽  
Crystalline Materials ◽  
Large Size ◽  
Transmission Electron ◽  
New Type ◽  
Diffraction Patterns ◽  
Orientation Determination

Recent advances in the automatic indexing of backscatter Kikuchi diffraction patterns on the scanning electron microscope (SEM) has resulted in the development of a new type of microscopy. The ability to obtain statistically relevant information on the spatial distribution of crystallite orientations is giving rise to new insight into polycrystalline microstructures and their relation to materials properties. A limitation of the technique in the SEM is that the spatial resolution of the measurement is restricted by the relatively large size of the electron beam in relation to various microstructural features. Typically the spatial resolution in the SEM is limited to about half a micron or greater. Heavily worked structures exhibit microstructural features much finer than this and require resolution on the order of nanometers for accurate characterization. Transmission electron microscope (TEM) techniques offer sufficient resolution to investigate heavily worked crystalline materials.Crystal lattice orientation determination from Kikuchi diffraction patterns in the TEM (Figure 1) requires knowledge of the relative positions of at least three non-parallel Kikuchi line pairs in relation to the crystallite and the electron beam.

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