Transit satellite system timing capabilities

Current time transfer capabilities of the Transit Satellite System are reviewed. Potential improvements in the changes in equipment and operational procedures using operational satellites are discussed

Employer-Sponsored Training in Stabilisation and Growth Policy Perspectives

In Europe, accounting standards prevent larger expenditures on employer-sponsored training from being treated as investments. Using Sweden as example, we discuss two consequences for training. First, the timing: training will be conducted when income is large enough for training costs to be deducted without loss. This is more often possible during booms than recessions, providing a stabilisation policy dimension to training. Second, the volume: the training opportunity cost (foregone production) is largest during booms. Hence, training tends to be smaller than if conducted during downturns, possibly limiting growth.We formulate two proposals that can make training more counter-cyclical and increase the amount of training.Training; Accounting System; Timing; Growth

Strip-Tillage Effects on Corn Performance and Soil Properties

The perceived effect of no-tillage on soil temperature, soil moisture conditions, soil compaction, soil productivity, and nitrogen movement and availability has become a major concern among producers considering adopting this tillage system. No-tillage presents a unique challenge in poorly drained soils, in which certain surface soil properties are affected due to the absence of tillage as a corrective measure. Effective tillage systems create an ideal seedbed condition (i.e., soil moisture, temperature, and penetration resistance) for plant emergence, plant development, and unimpeded root growth. However, the integration of tillage and nitrogen (N) management (i.e., type of tillage system, timing of tillage system, timing of N application, and N rate) also presents significant challenges for producing corn, sustaining soil productivity, and improving water quality

Investigation of the dynamic range problem and providing software support for the AOL system

The present scheme for providing system timing for the airborne oceanographic lidar (AOL) system is not completely satisfactory. The possibility of using a digital approach to generate the forty pulses needed to energize the gates leading to the charge digitizers was investigated. The solution in terms of general analog and digital circuitry is straightforward. The crystal oscillator provides a stable frequency source which is used as a clock to the ring counter. The ring counter propagates a pulse from stage one to stage forty. Each of the outputs has an amplifier for isolation. This design is easy to implement in the frequency range up to 50 MHZ. Because a gate pulse width of from about 2 to 6 ns is needed for the AOL system, this dictates an input clock frequency to the shift register of from 100 MHA to 500 MHA. Problems associated with generating pulses in this range of operation are examined and an alternate solution is discussed

Spike processing model of the brain

The timing of a spike within a specific time period is used to identify a place in space (input terminal) and/or sense changes in energy or position in the environment, and is used to determine the motion of an actuator or the activation of a place in space (output terminal). The timing of a spike is specified by a sensor or a time delay memory cell that is preset (predetermined) or set through experience (empirical). Time delay memory cells are arranged in decoding networks that activate specific output terminals based upon the timing of incoming spike trains, or arranged in encoding networks that generate spike trains from activated input terminals. These spike trains form semi-axes that can transmit large quantities of information in one direction through a single conductor, and are essential in the transmission of information from peripheral neurons to and from the brain through the spinal chord

Kinematic Structure of Machines With Electronic System Timing Drive For Cutting a Two Step Chervyakov

Рассмотрены конструктивные особенности двухшагового червяка, обеспечивающие его сопряжение с традиционным одношаговым червячным колесом. Показано, что разношаговость такого червяка обусловлена заменой цилиндрической начальной поверхности витка конической. Предложен способ нарезания названного червяка чашечным резцом в виде зубчатого колеса с профилем зуба, форма которого является сопряженной при обкате с профилем резьбы нарезаемого червяка. Разработана на основе специализированных станков с механическими связями для нарезания червяков чашечным резцом кинематическая структура станка с индивидуальными регулируемыми приводами исполнительных органов. Предложен вариант системы синхронизации регулируемых приводов на базе типовых интегральных схем. = Design features of the two-step worm to ensure his pairing with the traditional one-step worm gear It is shown that such worm raznoshagovost replacement due cylindrical primary coil of the conical surface. Provides a method of cutting a worm called the cup cutter in the form of gear tooth profile, whose shape is complementary with rounding profile thread being cut worm. Developed on the basis of specialized machines with mechanical constraints for tapping the cup cutter worms kinematic structure of the machine with variable speed drives individual executive. A variant of the synchronization variable speed drives on the basis of standard integrated circuits

Results of using the global positioning system to maintain the time and frequency synchronization in the Deep Space Network

There are two hydrogen maser clocks located at each signal processing center (SPC) in the DSN. Close coordination of the time and frequency of the SPC clocks is needed to navigate spacecraft to the outer planets. A recent example was the Voyager spacecraft's encounter with Uranus in January 1986. The clocks were adjusted with the goal of minimizing time and frequency offsets between the SPCs at encounter. How time and frequency at each SPC is estimated using data acquired from the Global Positioning System Timing Receivers operating on the NBS-BIH (National Bureau of Standards-Bureau International de l'Heure) tracking schedule is described. These data are combined with other available timing receiver data to calculate the time offset estimates. The adjustment of the clocks is described. It was determined that long range hydrogen maser drift is quite predictable and adjustable within limits. This enables one to minimize time and frequency differences between the three SPCs for many months by matching the drift rates of the three standards. Data acquisition and processing techniques using a Kalman filter to make estimates of time and frequency offsets between the clocks at the SPCs and UTC(NBS) (Coordinated Universal Time realized at NBS) are described