Abstract In this study, based on the energy balance for different components of a double-layered vacuum-tube solar collector with U-tube, thermal performance unit is investigated separately using an analytical and quasi-dynamic method. The model used in study determines temperature distribution longitudinal radial directions. research, effects physical parameters heat transfer including size co...

The response of vacuum to the presence of external conditions is the subject of this work. We consider a generalization of the Casimir effect in the presence of curved boundaries on which a sharp potential is concentrated. The profile of the potential is a delta function, which has some features in common with a hard boundary and some with a smooth background field. The boundaries investigated ...

A ferroelectric cathode is employed for the first time as the electron-beam source in a microwave amplifier tube. A PLZT 12/65/35 ferroelectric ceramic with a high dielectric constant ( 4000) is used in a form of a hollow cathode. The tube is operated in poor vacuum conditions (2 10 Torr) at room temperature, in a mechanism of a cyclotron-resonance maser amplifier. The device operates near the ...

The interior of the color flux tube joining a quark pair can be probed by evaluating the correlator of pair of Polyakov loops in a vacuum modified by another Polyakov pair, in order to check the dual superconductivity conjecture, which predicts a deconfined, hot core. We also point out that at the critical point of any 3D gauge theories with a continuous deconfining transition the Svetitsky-Yaf...

Performance and reliability of medical X-ray sources for imaging humans are crucial from ethical, clinical and economic perspectives. This overview will treat the aspects to consider for investment of equipment for medical X-ray imaging. Recent X-ray tubes deliver enhanced reliability and unprecedented performance. But, metric for benchmarking has to change. Modern terms for product comparison ...

Results of design and simulation of a 0.2 THz traveling-wave-tube vacuum power amplifier with a sheet electron beam and grating slow-wave structure (SWS) are presented. Electromagnetic properties of the SWS such as dispersion and interaction impedance are calculated. Smallsignal and large signal gain curves are studied.

A contact lens may be removed from the eye either manually or by using a small rubber sucker. The removal of lenses by the rubber sucker technique is difficult at times, especially when the lens is fenestrated, as the vacuum cannot be maintained. Assistance in the removal of the lens may be obtained by modifying existing rubber suckers. The bulb is cut off with a sharp blade and into the lumen ...

The electrical resistivity of pure liquid selenium has been measured by many investigators [ 1 — 7 ] ; yet only a few of them describe the way in which their samples were prepared. Abdullaev et al. [3] and later Gobrecht et al. [4] and Koningsberger [5] have found that small amounts of oxygen have an enormous influence on the electrical resistivity of the liquid. Furthermore it was found [3, 5]...

Infected pancreatic necrosis needs to be drained; nowadays this is mostly done by endoscopic means. As yet, few cases of transgastric endoscopic vacuum therapy (EVT) have been reported [1–3]. This is the first case to be reported in which a new open-pore film drainage (OFD) device was used. A 70-year-old man became septic because of infected pancreatic necrosis. Initially the cyst was drained w...

A schematic view of the furnace used for the CdTe nanowire synthesis by the vapor-liquid-solid (VLS) technique is shown in figure S1. In this system, the carrier gas transports the source material vapors from upstream to downstream in the quartz tube. The CdTe powder (Alfa company, 99.99%), 0.03g for all samples, was placed in a high-purity alumina crucible located at the source position of the...