Safety Evaluation of Arch Dam Subjected to Underwater Contact Explosion

The stability of an arch dam can be significantly damaged by an extreme underwater explosion. This study proposed a damage index for assessing the degree of local damage of an arch dam after the dam was subjected to an underwater explosion. The damage index was applied to assess local damage at the middle part of the dam, surcharge holes, and abutment. A model was developed to evaluate the stability of the entire dam based on the spatial distribution of damage and the damage on the base interface. Results showed that local explosion damage at flood discharge holes or abutments might cause instability of the arch dam. When the contact explosion action location is on the abutment, it only needs 310 kg to cause the overall damage of the arch dam, while when the action location is on the middle part of the dam, the quantity of explosive required is 2800 kg.

GENERAL REMARKS ON BASIC ACTUALITIES WITHIN OUR LIFE AND EDUCATION DURING FIRST 20 YEARS OF 21st CENTURY

Development of Human personal as well as social Life means continuing physical and spiritual (mental) changes all around them and within them. Corresponding changes traditionally reflected by humans as evolution (reformational) or revolution (transformational) processes, that are realizing corresponding quantitative or qualitative steps within the development of people’s Life Activities. First 20 years of 21-st Century presented a real start of serious qualitative changes as a process of implementation up to date achievements of modern Science and Technologies. These are transformational changes not only within physical background of our traditional Life, but fast developing of corresponding changes also within our spiritual (or mental) Life (Broks, 2016). The central phenomenon within the mentioned processes above today is the development of overall computerization of physical as well as mental Life Activities of Humans. Global, regional, local explosion of information as an artefact of revolution within Computer Science and Information Technology marks the above mentioned beginning of the 21-st century. So, our life today is becoming more and more complex by means of increasing diversity and speed of corresponding changes. Virus COVID-19 attack has just only accelerated these changes. Global turnover of Biological as well as Computer viruses is part of modern Life today for tomorrow.

Local environments of SNe Ic and Ic-BL

We have observed the local explosion environments of a sample Type Ic and Type Ic-BL Supernove (SNe) selected from both targeted and non-targeted surveys using VLT/VIMOS in IFU-mode. It is believed that by probing the local surroundings of the parent stellar populations of these types of SNe, valuable information can be gained about the physical conditions, which affect the type of SNe produced. The different kinds of SNe produced are determined by the initial mass and metallicity of the stellar progenitor, as well as by the metallicity-dependent mass loss in the stellar winds at the end phase of their evolution and the interaction with a sufficiently close companion star.

The Study on the Ineffective Mechanism of Aluminum Alloy Spot Welding Electrode

This study explored the electrode excessive burning reason caused by aluminum resistance spot welding and proposed a new electrode failure mechanism. The test shows that the oxide film of aluminum alloy workpieces causes the contact of non-uniform points between electrode and workpieces and instantaneously leads to a local explosion when setting up an electric circuit, bringing about the plastic deformation of the electrode surface in the local area, which will in turn exacerbate the contact of non-uniform points between electrode and workpieces so as to result in the serious burnout of electrodes under the interaction between local explosions and Cu-Al alloying. Cu-Al alloying and brittle material on the electrode surface caused by the contact of non-uniform points will firstly detach from the surface of electrode under the tearing force of mechanical , so that the electrode surface becomes more uneven.

On the evolution of compression pulses in an exploding atmosphere: initial behaviour

The development in space and time of a plane initial disturbance to a spatially uniform exploding atmosphere is analysed on the assumption that the disturbance amplitude is comparable in magnitude with the inverse (dimensionless) activation energy of the explosion reaction. Particular attention is focused on the shock-fitting problem, which has features that distinguish it from its inert-atmosphere counterpart.Using the positive half of a sine wave to typify an isolated compression perturbation, it is found that the amplifying effect of the ambient reaction leads to very rapid shock wave development, which depends significantly on the spatial extent of the disturbance. The latter also influences the question of whether local explosion (local explosion is recognized here as a logarithmically unbounded growth of the disturbance amplitude; in other words as a local breakdown of the present approximations) occurs at the shock wave or some distance behind it. The subsequent evolution of these two states will no doubt be significantly different, but the answer to this speculation must await extension of the present theory to encompass the rapid events that ensue near the local explosion regions.