Formal Verification of Full-Wave Rectifier: A Case Study

We present a case study of formal verification of full-wave rectifier for analog and mixed signal designs. We have used the Checkmate tool from CMU [1], which is a public domain formal verification tool for hybrid systems. Due to the restriction imposed by Checkmate it necessitates to make the changes in the Checkmate implementation to implement the complex and non-linear system. Full-wave rectifier has been implemented by using the Checkmate custom blocks and the Simulink blocks from MATLAB from Math works. After establishing the required changes in the Checkmate implementation we are able to efficiently verify the safety properties of the full-wave rectifier.Comment: The IEEE 8th International Conference on ASIC (IEEE ASICON 2009), October 20-23 2009, Changsha, Chin

Development of Virtual Resistance Meters using LabVIEW

This paper presents the development of three virtual resistance meters using LabVIEW. The unknown resistance is measured in terms of a known resistance of high accuracy by employing (a) a real dc voltage source, (b) a real dc current source, and (c) a virtual dc voltage source. In each case, ratio of two voltage signals is acquired by a single-ADC based multichannel data acquisition card. Therefore error of the ADC gets cancelled, when ratio of two voltages is used in the final calculation of the value of unknown resistance. The first two VRMs use a real excitation source and are thus semi-virtual instruments, whereas the third one is fully-virtual as the excitation source is also implemented in the LabVIEW software along with DAC section of the data acquisition card. The three virtual resistance meters have been successfully implemented. The principle of ratio-metric measurement used makes the accuracy (uncertainty) of final measurement free from the uncertainties of the ADC, the DAC and the excitation source. Standard deviations of the readings taken with the three VRMs have been evaluated and compared. It is concluded that the fully-virtual instrument has the lowest and excellent value of standard deviation

Free-energy functional for freezing transitions: Hard sphere systems freezing into crystalline and amorphous structures

A free-energy functional that contains both the symmetry conserved and symmetry broken parts of the direct pair correlation function has been used to investigate the freezing of a system of hard spheres into crystalline and amorphous structures. The freezing parameters for fluid-crystal transition have been found to be in very good agreement with the results found from simulations. We considered amorphous structures found from the molecular dynamics simulations at packing fractions $\eta$ lower than the glass close packing fraction $\eta_{J}$ and investigated their stability compared to that of a homogeneous fluid. The existence of free-energy minimum corresponding to a density distribution of overlapping Gaussians centered around an amorphous lattice depicts the deeply supercooled state with a heterogeneous density profile

The 9-1-1 checkpoint clamp stimulates DNA resection by Dna2-Sgs1 and Exo1

Single-stranded DNA (ssDNA) at DNA ends is an important regulator of the DNA damage response. Resection, the generation of ssDNA, affects DNA damage checkpoint activation, DNA repair pathway choice, ssDNA-associated mutation and replication fork stability. In eukaryotes, extensive DNA resection requires the nuclease Exo1 and nuclease/helicase pair: Dna2 and Sgs1^(BLM). How Exo1 and Dna2-Sgs1^(BLM) coordinate during resection remains poorly understood. The DNA damage checkpoint clamp (the 9-1-1 complex) has been reported to play an important role in stimulating resection but the exact mechanism remains unclear. Here we show that the human 9-1-1 complex enhances the cleavage of DNA by both DNA2 and EXO1 in vitro, showing that the resection-stimulatory role of the 9-1-1 complex is direct. We also show that in Saccharomyces cerevisiae, the 9-1-1 complex promotes both Dna2-Sgs1 and Exo1-dependent resection in response to uncapped telomeres. Our results suggest that the 9-1-1 complex facilitates resection by recruiting both Dna2-Sgs1 and Exo1 to sites of resection. This activity of the 9-1-1 complex in supporting resection is strongly inhibited by the checkpoint adaptor Rad9^(53BP1). Our results provide important mechanistic insights into how DNA resection is regulated by checkpoint proteins and have implications for genome stability in eukaryotes

A Family of Difference-cum-Exponential Type Estimators for Estimating the Population Variance Using Auxiliary Information in Sample Surveys

Abstract Using auxiliary information, a family of difference-cum-exponentia

SALR: Secure adaptive load-balancing routing in service oriented wireless sensor networks

Congestion control and secure data transfer are the major factors that enhance the efficiency of Service Oriented Wireless Sensor Networks. It is desirable to modify the routing and security schemes adaptively in order to respond effectively to the rapidly changing Network State. Adding more complexities to the routing and security schemes increases the end-to-end delay which is not acceptable in Service Oriented WSNs which are mostly in real time. We propose an algorithm Secure Adaptive Load-Balancing Routing (SALR) protocol, in which the routing decision is taken at every hop considering the unforeseen changes in the network. Multipath selection based on Node Strength is done at every hop to decide the most secure and least congested route. The system predicts the best route rather than running the congestion detection and security schemes repeatedly. Simulation results show that security and latency performance is better than reported protocols

DRFSD: Directed Restricted Flooding For Secure Data-Aggregation In Wireless Sensor Networks

Secured Data Transmission is a major issue in Wireless Sensor Networks (WSNs). In this paper we have proposed Directed Restricted Flooding Protocol (DRFSD) in WSNs. This protocol is better than H-SPREAD (Hybrid Security Protocol for REliable dAta Delivery). In DRFSD, alternate multipaths are selected based on the sensor node, that are placed at 180? direction with the Base Station (BS). This scheme is ef?cient in sending the Data Packets to the Base Station in shorter duration than the H-SPREAD. Simulation Results show that our algorithm approach performs well with respect to latency in comparison with earlier algorithm

The evolution of luminosity, colour and the mass-to-luminosity ratio of Galactic open clusters: comparison of discrete vs. continuous IMF models

(abridged) We found in previous studies that standard Simple Stellar Population (SSP) models are unable to describe or explain the colours of Galactic open clusters both in the visible and in the NIR spectral range. (...) We construct a numerical SSP-model, with an underlying Salpeter IMF, valid within an upper $m_u$ and lower $m_l$ stellar mass range, and with total masses $M_c=10^2...10^4\,m_\odot$ typical of open clusters. We assume that the mass loss from a cluster is provided by mass loss from evolved stars and by the dynamical evaporation of low-mass members due to two-body relaxation. The data for the latter process were scaled to the models from high-resolution N-body calculations. We also investigate how a change of the $m_l$-limit influences magnitudes and colours of clusters of a given mass and derive a necessary condition for a luminosity and colour flash. The discreteness of the IMF leads to bursts in magnitude and colour of model clusters at moments when red supergiants or giants appear and then die. The amplitude of the burst depends on the cluster mass and on the spectral range; it is strongly increased in the NIR compared to optical passbands. In the discrete case, variations of the parameter $m_l$ are able to substantially change the magnitude-age and $M/L$-age relations. For the colours, the lowering of $m_l$ considerably amplifies the discreteness effect. The influence of dynamical mass loss on colour and magnitude is weak, although it provides a change of the slopes of the considered relations, improving their agreement with observations. For the Galactic open clusters we determined luminosity and tidal mass independent of each other. The derived mass-to-luminosity ratio shows, on average, an increase with cluster age in the optical, but gradually declines with age in the NIR. The observed flash statistics can be used to constrain $m_l$ in open clusters.Comment: 15 pages, 13 figures, accepted for publication in Astronomy and Astrophysic