Temperature-stabilized, triggerable microelectronic astable multivibrator starts reliably

Multiple chip custom block, MIC construction is used to fabricate an ultracompact, low-power astable multivibrator. The design provides a multivibrator that free runs, eliminating lockup, is triggerable, pulling into synchronization with an external signal source, and permits design flexibility for controlling the frequency variations with temperature

Long term frequency stability analysis of the GPS NAVSTAR 6 Cesium clock

Time domain measurements, taken between the NAVSTAR 6 Spacecraft Vehicle (SV) and the Vandenberg Global Positioning System (GPS) Monitor Site, by a pseudo random noise receiver, were collected over an extended period of time and analyzed to estimate the long term frequency stability of the NAVSTAR 6 onboard frequency standard, referenced to the Vandenberg MS frequency standard. The technique employed separates the clock offset from the composite signal by first applying corrections for equipment delays, ionospheric delay, tropospheric delay, Earth rotation and the relativistic effect. The data are edited and smoothed using the predicted SV ephemeris to calculate the geometric delay. Then all available passes from each of the four GPS monitor stations, are collected at 1-week intervals and used to calculate the NAVSTAR orbital elements. The procedure is then completed by subtracting the corrections and the geometric delay, using the final orbital elements, from the composite signal, thus leaving the clock offset and random error

Evaluation of Composting of Municipal Solid Waste

A field-scale commercial compost study was conducted to evaluate the impact of the Bio-Environmental Resource Recovery International (BERRI) Microbial Assisted Regeneration System (MARS) process, specifically its proprietary microbial inocula, on compost production of various agricultural waste and municipal solid waste (MSW) mixtures. Treated and control windrows were constructed to compare the MARS inoculum by quantity and quality of compost produced, organic stabilization time, and individual component sorting (i.e., green waste, wood, agriculture waste, food waste, MSW, C&D debris, and tires). Specific VOC and SVOC compounds, as well as a common pesticide, carbaryl, were added specifically for this study and the compounds were analyzed for degradation rates. The quality of the compost product was assessed using a method developed for classifying municipal solid waste compost. The quantity of compost produced was determined by screening the entire volumes of each pile to determine a gross production of compost for each pile. Compost samples were analyzed by headspace gas chromatography mass spectrometry for VOCs, methylene chloride extraction and gas chromatography mass spectrometry for SVOCs, and methanol extraction and high-performance liquid chromatography mass spectrometry for carbaryl. The quality of compost was found to have a very low nutrient capacity making the compost only useable as a soil conditioner. Treated piles showed a significantly larger amount of compost production and a decreased time for organic stabilization. No significant degradation of plastics or woods components was observed in any of the treatments used in the study

Amorphous silica between confining walls and under shear: a computer simulation study

Molecular dynamics computer simulations are used to investigate a silica melt confined between walls at equilibrium and in a steady-state Poisseuille flow. The walls consist of point particles forming a rigid face-centered cubic lattice and the interaction of the walls with the melt atoms is modelled such that the wall particles have only a weak bonding to those in the melt, i.e. much weaker than the covalent bonding of a Si-O unit. We observe a pronounced layering of the melt near the walls. This layering, as seen in the total density profile, has a very irregular character which can be attributed to a preferred orientational ordering of SiO4 tetrahedra near the wall. On intermediate length scales, the structure of the melt at the walls can be well distinguished from that of the bulk by means of the ring size distribution. Whereas essentially no structural changes occur in the bulk under the influence of the shear fields considered, strong structural rearrangements in the ring size distribution are present at the walls as far as there is a slip motion. For the sheared system, parabolic velocity profiles are found in the bulk region as expected from hydrodynamics and the values for the shear viscosity as extracted from those profiles are in good agreement with those obtained in pure bulk simulations from the appropriate Green-Kubo formula.Comment: 23 pages of Late