An innovative method for fabricating the reference cell for a Rubidium (Rb) integrated atomic clock is presented. This method uses low-temperature solder sealing technique for producing mini-cells of the size of 14 x 10 x 3 mm, suitable for Rb miniature atomic clocks. Top and bottom of the cell consists of two glass slides. An LTCC (Low-Temperature Cofired Ceramic) module of 2 mm thickness, equ...

With the increasing improvement of national ecological standards, eco-environmental problems caused by super thick coal seam mining in western China are becoming more and serious. The failure law weak overburden stratum is an important factor affecting safe coal. characteristics weakly cemented under high-intensity area were studied. For this purpose, a case study was conducted 1101 working fac...

A fracture expansion criterion of hydraulic fracturing was suggested to deal with the hard and stable roof control in coal mines. An experiment designed for control, reliability model verified. Four different types holes technology were setup room, a fully mechanized caving face implemented.

Coal is the main energy source in China, and spontaneous combustion of coal one disasters mines. Fully mechanized caving top mining technology widely used Under comprehensive action multiple factors, gas generated by oxidation low oxygen goaf easy to rush working face, resulting lower concentration upper corner exceeding harmful concentration. It seriously threatens health underground workers n...

thermal decomposition of two coal samples obtained from top seam sibi (tss) and sore range quetta (srq) coal fields in their raw and acid washed forms were carried out in an open type tubular pyrolyzer coupled to a gas chromatograph with fid. elemental analyses were carried out with scanning electron microscope-energy dispersive x-rays (sem-edx) analyzer. effect of inherent mineral contents on ...

Longwall shearers’ haulage system of the Eicotrack type, used most often nowadays, is presented in this article. Its disadvantages, causing problems with a correct operation mechanized longwall shearer systems, are discussed. The concept innovative Flextrack, which should reduce occurrence disadvantages mentioned above, described. A course and research results, connected rig tests Flextrack fun...

Purpose. On the basis of analysis and assessment geological conditions, technological parameters support methods a longwall, author has pointed out causes rules phenomenon face spall roof falling in fully mechanized longwall. From there, proposes some solutions to prevent this ensure safety Methods. The statistical, survey actual field data are used achieve research results. Findings. results a...

Equipment control functions that were once hardwired are being implemented with software and very large scale integrated (VLSI) devices. Often this transition has resulted in increased flexibility, improved quality, and decreased costs. At the same time, it has created new concerns and challenges concerning worker safety. The visible and welldefined ladder diagram for relay-logic has been repla...