on the affected circuit node. If the magnitude of this spike In this paper, we present a novel circuit design approach is sufficiently large, an erroneous value may be computed for radiation hardened digital electronics. Our approach is by the circuit. This is particularly problematic for memobased on the use of shadow gates, whose task it is to prories, which can flip their stored state as a result of such a tect the primary gate in case it is struck by a heavy cosmic radiation strike. Combinational logic may also be affected ion. We locally duplicate the gate to be protected, and conby such strikes, if the resulting glitch occurs at the time the nect a pair of transistors (or diodes) between the outputs circuit outputs are being sampled. Such bit reversals are reof the original and shadow gates. These transistors turn on ferred to as Single Event Upsets (SEUs) [12], or soft errors when the voltages of the two gates deviate during a radiation in the case of memory. strike. Our experiments show that at the level of a single The charge deposition rate is also referred to as the Linear gate, our circuit structure has a delay overhead of about 4% Energy Transfer (LET). Cosmic ions have varying LETs, on average, and an area overhead of over 100%. At the cirand they result in the deposition of a charge Q in a semicuit level, however, we do not need to protect all gates. We conductor diffusion region of depth t by the following forpresent a methodology to selectively protect specific gates of mula [11].the circuit in a manner that guarantees radiation tolerance for the entire circuit. With this methodology, we demon-Q= 0.01036-L t strate that at the circuzt level, the delay overhead is about 4% and the placed-and-routed area overhead is 30%, comHere L is the LET of the ion (expressed in MeV/cm2/mg), pae to an unrtce cicifr dea mape designs) t is the depth of the collection volume (expressed in microns), and Q is charge in pC. The amount of charge that Categories and Subject Descriptors: B.8.2 [Performance is required to cause a bit to be sampled incorrectly is reand Reliability]: Reliability, Testing, and Fault-Tolerance ferred to as the critical charge, Qc [13]. With diminishing General Terms: Design, Reliability process feature sizes and supply voltages, SEU problems are
Pre-decomposed (15 days), turkey litter was mixed with cow dung (1:1, w/w) and vermicomposted with earthworm, Perionyx ceylanensis for 60 days. The vermicompost thus obtained was amended with regular farmers practice in the field soil for the cultivation of paddy (Oryza sativa, ADT-37) in six different treatments with and without vermicomposts (RBD). Before application of vermicompost and after the harvesting of paddy, composite soil samples from each plot were taken and subjected to the analyses of pH, organic carbon, available NPK contents and soil microflora. The E.C., total nitrogen, potassium, phosphorus, calcium, manganese, copper, iron and zinc showed increase in vermicomposts than in the worm un-inoculated composts. The organic carbon, C/N and C/P ratio showed reduction in all the vermicomposts over composts. The results on the growth and yield of paddy with the amendment of vermicompost showed notable increase in 40 kg/plot vermicompost amendment with regular farmers practice. All the parameters considered on the growth and yield of paddy for the study were higher in vermicompost amendments in a dose-dependent manner followed by the regular farmer practice and universal control. The average pH range recorded in all the plots before application of vermicomposts and farmers practice showed slight reduction in vermicompost amended plots after harvesting of paddy. The organic carbon and available NPK contents also showed increase in vermicompost applied plots. The results on the status of microbial population in soils amended with various vermicompost treatments and farmers practice after harvesting of paddy (ADT-37) showed an increase over initial and control plots. The final microbial population in plots amended with different treatments was found to be dose-dependent.
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