Exact transient analysis of a circulant queuing network

AbstractCirculant matrices possess unusual and interesting properties. These properties have been exploited to obtain the transient solution in closed form for a circulant queuing network that models a distributed query processing system. The sojourn time of a customer in the circulant queuing network is determined. A semi-Markov generalisation of this network is also studied

Optimization of Cutting Performance Using Vegetable Oil in Drilling of AA 6082 T6 by Minimum Quantity Lubrication

Industries were facing crucial problems on disposal of used lubricants who caused environmental pollution directly as well as indirectly. Also, surface quality was seen at lower rate using flood lubrication. The drilling process generates large energy and most of the energy is converted to heat. The intense heat affects the mechanical properties of the work material and the drill. Conventional coolants are used to control the heat and carry away the chips formed. The major aim of this study is to optimize the machining parameters using mustard oil as a MQL coolant (10ml/h mixing of oil with compressed air) and experiments were carried out with aluminium alloy 6082 T6 which possess high thermal conductivity. Later, Taguchi method was used in small number of experiments to study the parameters, using orthogonal arrays derived from the design of experiments theory. Process parameters were used for this study such as cutting tool (T), feed rate (F) and Speed (N). The performance characteristics were measured, which are surface roughness (S) and kerf angle (Ka). ANOVA is used to find the most influencing factor in drilling. In this study, results include the most contribution factor i.e., cutting tool which contributes 89.3% followed by feed rate of 6.73% and spindle speed 2.10 %. Conformation test has been carried out for improving grey relational analysis by 10.15%. In addition to that surface of chips were examined at machining region under scanning electron microscope (SEM)

Unified Defense against DDoS Attacks

Abstract. With DoS/DDoS attacks emerging as one of the primary security threats in today's Internet, the search is on for an efficient DDoS defense mechanism that would provide attack prevention, mitigation and traceback features, in as few packets as possible and with no collateral damage. Although several techniques have been proposed to tackle this growing menace, there exists no effective solution to date, due to the growing sophistication of the attacks and also the increasingly complex Internet architecture. In this paper, we propose an unified framework that integrates traceback and mitigation capabilities for an effective attack defense. Some significant aspects of our approach include: (1) a novel data cube model to represent the traceback information, and its slicing along the lines of path signatures rather than router signatures, (2) characterizing traceback as a transmission scheduling problem on the data cube representation, and achieving scheduling optimality using a novel metric called utility, (3) and finally an information delivery architecture employing both packet marking and data logging in a distributed manner to achieve faster response times. The proposed scheme can thus provide both per-packet mitigation and multi-packet traceback capabilities due to effective data slicing of the cube, and can attain higher detection speeds due to novel utility rate analysis. We also contrast this unified scheme with other well-known schemes in literature to understand the performance tradeoffs, while providing an experimental evaluation of the proposed scheme on real data sets

Butane-1,4-diyl bis­(pyridine-4-carboxyl­ate)

The mol­ecule of the title compound, C16H16N2O4, lies about an inversion centre; the butane chain adopts an extended zigzag conformation. The dihedral angle between the pyridine ring and the adjacent COO group is 3.52 (s14)°

Statistical Properties of Fluctuations: A Method to Check Market Behavior

We analyze the Bombay stock exchange (BSE) price index over the period of last 12 years. Keeping in mind the large fluctuations in last few years, we carefully find out the transient, non-statistical and locally structured variations. For that purpose, we make use of Daubechies wavelet and characterize the fractal behavior of the returns using a recently developed wavelet based fluctuation analysis method. the returns show a fat-tail distribution as also weak non-statistical behavior. We have also carried out continuous wavelet as well as Fourier power spectral analysis to characterize the periodic nature and correlation properties of the time series.Comment: 9 pages, 6 figures, Econophys-IV, Kolkata, 200

Stock assessment of seerfishes in the Indian seas

The annual average catch of seerfishes from the Indian seas was 45,0601 during 1995-'99, which constituted 1.8% of the total marine fish catch in India. State-wise Gujarat (28.5%) was the major producer followed by Tamilnadu (15.8%), Maharashtra (15.4%), Andhra Pradesh (11.4%) and Kerala (10.5%). Gill net is the dominant gear in exploiting seerfish followed by trawl, hooks & line, boat seines, shore seines and purse seines. Among the five species, the kingseer Scomberomorus commerson (59.0%) and the spotted seer S. guttatus (35.1%) sustained the fishery, while the streaked seer S.lineolatus and the wahoo Acanthocybium solandri formed only a negligible portion of the fisher

Collinear cluster tripartition as sequential binary fission in the 235^{235}U(nth_{\rm th},f) reaction

The mechanism leading to the formation of the observed products of the collinear cluster tripartition is carried out within the framework of the model based on the dinuclear system concept. The yield of fission products is calculated using the statistical model based on the driving potentials for the fissionable system. The minima of potential energy of the decaying system correspond to the charge numbers of the products which are produced with large probabilities in the sequential fission (partial case of the collinear cluster tripartition) of the compound nucleus. The realization of this mechanism supposes the asymmetric fission channel as the first stage of sequential mechanism. It is shown that only the use of the driving potential calculated by the binding energies with the shell correction allows us to explain the yield of the true ternary fission products. The theoretical model is applied to research collinear cluster tripartition in the reaction $^{235}$U(n$_{\rm th}$,f). Calculations showed that in the first stage of this fission reaction, the isotopes $^{82}$Ge and $^{154}$Nd are formed with relatively large probabilities and in the second stage of sequential fission of the isotope Nd mainly Ni and Ge are formed. This is in agreement with the yield of the isotope $^{68}$Ni which is observed as the product of the collinear cluster tripartition in the experiment.Comment: 20 pages, 9 figure

Status of exploitation of seerfishes in the Indian seas

Seerfish production from the Indian seas during the past five decades from 1950s to 1990s, showed an increasing trend. The annual catch increased from 4,505 t in 1953 to 54,8761 in 1998. The average annual catch during the five decadal periods k-aried from 7,278 t in 1950-'59 to 41,575 t in 1990-'99 contributing 1.5% and 1.75% respectively to the total marine fish catch of India. However, the rate of increase through the successive decades decreased indicating the attainment of op- ;imum level of production currently. During 1950-'59, the east coast contributed more (60%) than the west coast (40%), which changed to 36:64 during 1990-'99. iVmong the maritime states of India, Gujarat (25.88%), Maharashtra (16.09%), familnadu (13.59%), Kerala (13.07%) and Andhra Pradesh (12.68%) were the prime seerfish producers during 1990-'99. Gill net (64.8%) was the dominant gear, folowed by trawl (17.4%) and hooks and line (4%) with an average catch rate of 8.1 <g/unit, 0.24 kg/hr and 3.7 kg/unit respectively during 1995-'99. Among the five species, the fishery was sustained only by two species viz., the king seer Scomberomorus commerson and the spotted seer S.guttatus

Heptacarbonyl-1κ3 C,2κ4 C-(4-phenyl­pyridine-1κN)di-μ-phenyltellurido-1:2κ4 Te:Te-dirhenium(I)

In the title complex, [Re2(C6H5Te)2(C11H9N)(CO)7], two Re atoms are coordinated in slightly distorted octa­hedral coordination environments and are bridged by two Te atoms, which are coordinated in trigonal-pyramidal environments. The torsion angle for the Te—Re—Te—Re sequence of atoms is 17.06 (3)°. The crystal structure is stabilized by weak C—H⋯O and C—H⋯π inter­actions. In addition, there are Te⋯Te distances [4.0392 (12) Å] and O⋯O distances [2.902 (19) Å] which are shorter than the sum of the van der Waals radii for these atoms. A short inter­molecular lone pair⋯π distance [C O⋯Cg = 3.31 (2) Å] is also observed

Stock assessment of coastal tunas in the Indian seas

Tuna and billfish production from the Indian coastal waters, Lakshadweep and Andaman and Nicobar islands during the period 1985-'99 averaged 40,204 t. The contribution by E.affinis, Athazard, T.tonggol, K.pelamis and T.albacares (young ones) were 18,5041,6,8521,3,093 t, 3,3921 and 2,2111 respectively. Drift gill net was the major gear employed in the coastal tuna fishery. The length frequency data collected on the above species during 1990-'98 at seven centres along the Indian coast were analysed employing FiSAT programme to estimate their growth and mortality parameters, exploitation rates and relative yield per recmit