seals and clay sealings are the most important cultural material of sasanian period. there have been a few seals and bullas of various periods retained in the moghadam museum of tehran. these materials have not been introduced so far. authors of the present paper aim at to study and introduce the sasanian seals and bullas of this museum especially those bearing animal symbolic motifs. we do thi...

We present the history and analysis of different wake field effects throughout the operational life of the PEP-II SLAC B-factory. Although the impedance of the high and low energy rings is small, the intense high current beams generated a lot of power. The effects from these wake fields are: heating and damage of vacuum beam chamber elements like RF seals, vacuum valves , shielded bellows, BPM ...

The reliability and stability of the seal at fuel-supply end a rocket-engine turbopump are important factors in determining safety. Conventional single-stage floating rings used for isolation-sealing cryogenic media highly susceptible to operational instability during startup shutdown, which places demands on seals’ structure, size, material properties. In this study, two-stage floating-ring is...

Elastomeric seals are widely used to block fluids of high pressure. When multiple seals are installed in series and the spaces between the seals contain compressible fluids (e.g., gas or gas–liquid mixture), the seals often damage sequentially, one after another. Here, we demonstrate that the serial seals achieve high sealing capacity if individual seals undergo elastic leak, without material d...

Stern tube seals are a key component of the propulsion system ship. The purpose these sealing rings is to ensure reliable condition, preventing spillage lubricant environment. research on large rotary limited due their complex accessibility: stern located below seawater level moving A dynamic setup replicating operating conditions seal presented together with novel arrangement for monitoring fl...

we show  that a projective maximal submodule of afinitely generated, regular, extending module is a directsummand. hence, every finitely generated, regular, extendingmodule with projective maximal submodules is semisimple. as aconsequence, we observe that every regular, hereditary, extendingmodule is semisimple. this generalizes and simplifies a result of  dung and   smith. as another consequen...

An elastomeric seal may leak by elastic deformation without any material damage. We describe elastic leak using a theoretical model, and watch a seal deform and leak using a transparent experimental setup. The elastomer seals the fluid by forming contact with surroundinghardmaterials. As the fluid pressure increases, the contact stress also increases but not as much. When the fluid pressure sur...

Serological analysis was performed to detect Toxoplasma gondii and Neospora caninum infection in seals in Hokkaido. Serum samples were collected from 322 Kuril harbor seals (Phoca vitulina stejnegeri) at Nosappu, Akkeshi and Erimo, from 46 spotted seals (P. largha) at Nosappu, Erimo, Yagishiri Island, Hamamasu and Syakotan, and from 4 ribbon seals (P. fasciata) and a bearded seal (Erignathus ba...