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The dynamics of slightly curvedcantilevered tubular beams conveying fluid was investigated experimentally. Apart from exhibiting a rich dynamical behaviour, interest in the matter arises mostly because in real-world applications pipes conveying fluid are often subject to geometric imperfections, rendering a straight pipe curved. A bench-top-size apparatus consisting of a reservoir and a hanging straight or curved clamped-free pipe conveying fluid was utilized. Four different cases were explored: (i) a water-discharging straight pipe in air (in the reservoir filled with air), (ii) a water-discharging curved pipe in air, (iii) an aspirating straight pipe submerged in quiescent water (in the reservoir filled with water), and (iv) an aspirating curved pipe submerged in quiescent water. Making use of a contactless optical technique, the displacement time-series signal was obtained and analysed to characterize the nature of the motions. It was found that curved cantilevered pipes conveying fluid display quite interesting nonlinear fluid–structure interaction dynamics. For initially curved discharging pipes, a large flow-induced static deformation materialized prior to the onset of an oscillatory instability. Aspirating curved pipes, on the other hand, are subjected to weak flutter superimposed on a static deformation. [ABSTRACT FROM AUTHOR]

Every year near-Earth object (NEO) surveys discover hundreds of new asteroids, including the potentially hazardous asteroids (PHA). The possibility of impact with the Earth is one of the main motivations to track and study these objects. This paper presents a tether assisted methodology to deflect a PHA by connecting a smaller asteroid, altering the center of mass of the system, and consequently, moving the PHA to a safer orbit. Some of the advantages of this method are that it does not result in fragmentation, which could lead to another problem, and also the flexibility to change the configuration of the system to optimize the deflection according to the warning time. The dynamics of the PHA-tether-asteroid system is analyzed, and the amount of orbit change is determined for several initial conditions. Only motion in the plane of the orbit of the PHA around the Sun is considered, thus the PHA chosen for the simulations has low orbit inclination. Analysis of the dynamics of the system shows that the method is feasible for planetary defense. [ABSTRACT FROM AUTHOR]

DOS or Denial-of-service attacks are found in many forms and they're an explicit attempt to block the genuine access of user to the system via reducing availability of the system just similar to physical Dos attacks where for example intentionally the electrical power is removed. Sometimes the attacker may also play with a computing devices and make it inaccessible by altering the existem specification of the management information system. These physical intrusions are tackled by tough security measures and strategies. Although few software guards against some attacks, yet it flops to defend against DoS flooding attacks and it may further exploit unrestricted forwarding of internet packets. DDoS distributed denial of service attacks are another contiguous type of attack over the availability of Internet resources. The attackers are smart enough to penetrate into comparatively large number of computers exploiting weaknesses of different softwares so as to setup distributed attacks. These computers are unsuspecting in nature so they can be easily invoked for planning and attempting attack over more victim systems. Over the time the counter measures are developed attackers also improve the existing attack tools developing as well as imitating techniques for distributed denial-of-service attacks. So it is imperative develop complete expositions for defending against known attack variants of such kinds. However this procedure needs a complete understanding of techniques, prerequisites and scope used in diverse kinds of attacks. This paper tries to describe the scope of DDoS problem in possible comprehensive capacity. We have tried to propose new methods to categories different techniques used in DDoS attack, also categories attack networks and defining characteristics of different software tools that help to build up such attack networks. With this new approach we attempt to propose different classes' methods the target this problem during, before, and after actual DDoS attacks. This work envisioned to stimulate research into efficient creative an effective ramparts, detection mechanism and methods for such attacks. This intern may help to create broad and ample solutions providing generalized approach towards countering known as well as derived DDoS attacks. [ABSTRACT FROM AUTHOR]

In this paper, a novel predictive smooth variable structure filter (PSVSF) is presented for attitude synchronization during satellite formation flying (SFF). The strategy is proposed based on variable structure control concept and applies to any nonlinear system with modeling errors. Because the modeling errors in the PSVSF are not restricted to Gaussian noise only, the technique can deal with various kinds of uncertainties, parameter variations, or noises. It also has low computational burden; therefore, it is more general than other nonlinear estimation methods. Sufficient conditions to analyze the stability and characteristics of the PSVSF are presented. Simulations are performed to demonstrate the accuracy, robustness, and stability of the proposed PSVSF for the attitude synchronization estimation of the SFF system. [ABSTRACT FROM PUBLISHER]

A new set of linearized differential equations governing relative motion between satellites in a formation is derived, taking into account the effects of J2 as well as atmospheric drag. This set of equations is more convenient than the corresponding nonlinear equations for designing formation control system or for implementing guidance algorithms. It is assumed that the eccentricity of the chief's orbit is small. In addition, the corresponding constant linearized equations are also proposed without numerical integrated, which is more convenient for engineering applications. Simulations show that the results obtained from the linearized model are quite close to those obtained by integrating the nonlinear dynamics model. [ABSTRACT FROM AUTHOR]

Recently, active control of aeroelastic oscillations and the use of piezoelectric materials in vibration analysis and control of structures have been the subjects of many researches in air vehicle design. The present paper deals with the use of bonded piezoelectric sensors and actuators in control of aeroelastic oscillations of a cantilever plate under the effects of unsteady subsonic aerodynamic loading. The aerodynamic loading is calculated using a numerical panel method. The structural model of the plate undergoing small transverse oscillations is modeled using finite element formulation. The aerodynamic and structural models are coupled through an interactive computer model to transfer the data simultaneously and an active feedback control is applied to suppress the oscillations. A systematic method is also presented to obtain the gains of the feedback controller. The numerical results show that the controller can effectively reduce the amplitude of the oscillations in small amount of time and with small gains, hence lower cost. [ABSTRACT FROM PUBLISHER]

Background: Lacidipine (LCDP) is a 1,4-dihydropyridine derivative categorized as an anti-hypertensive Ca2+ channel blocker having very low solubility, and thus very low oral bioavailability, which presents a challenge to the formulation scientists. Homogeneous distribution of poorly water-soluble drugs like LCDP in polyvinylpyrrolidone (PVP), a hydrophilic carrier, is definitely a suitable way to improve the bioavailability of such drugs. Materials and Methods: The aim of the study was to develop a combined thermal, imaging, and spectroscopic approach, and characterize physical state, dissolution behavior, and elucidation of drug--PVP interaction in LCDP/PVP solid dispersion (SD) using differential scanning calorimetry (DSC), X-ray diffractometry (XRD), fourier transform infrared (FTIR) spectroscopy, and hot stage microscopy (HSM), which is the prerequisite for the development of a useful drug product. Results: Dissolution studies of LCDP and its physical mixture with PVP showed less than 50% release even after 60 min, whereas SD of LCDP/ PVP ratio of 1:10% w/w showed complete dissolution within 45 min. DSC and powder XRD proved the absence of crystallinity in LCDP/PVP SD at a ratio of 1:10% w/w. The FTIR spectroscopy indicated formation of hydrogen bond between LCDP and PVP. In the SD FTIR spectra, the -NH stretching vibrations and the -C=O stretch in esteric groups of LCDP shift to free -NH and C=O regions, indicating the rupture of intermolecular hydrogen bond in the crystalline structure of LCDP. Conclusion: Solid-state characterization by HSM, DSC, XRD, and FTIR studies, in comparison with corresponding physical mixtures, revealed the changes in solid state during the formation of dispersion and justified the formation of high-energy amorphous phase. [ABSTRACT FROM AUTHOR]

Satellites in formation work together to fulfill the role of a larger satellite. The purpose of this article is to develop a quasi-rigid body formulation for modeling and controlling such a formation as a single entity. In this article, a definition of a quasi-rigid body coordinate frame is presented, which, when attached to a formation, conveniently describes its orientation in space. Using this formulation, the equations of motion for a satellite formation are recast, and natural circular formations are expressed more succinctly. When the J2 perturbation is considered, a correction factor on the formation's spin rate is introduced. The control of a satellite formation can effectively be separated into (1) a control torque to maintain the attitude and (2) control forces that maintain the rigidity of the formation. With this in mind, a nonlinear Lyapunov controller is derived using the formulation, which acts on the formation as a whole. Simulations validate this controller and illustrate its utility for maintaining circular formations, in particular, in the presence of gravitational perturbations. [ABSTRACT FROM AUTHOR]

Attitude motion of satellites orbiting an asteroid is examined. The highly irregular shape of the asteroids along with their rotational states can lead to very interesting attitude dynamics. As a start, the case of uniform rotation of the asteroid is examined and attention focused on planar attitude motion (pitch). Four asteroids, Vesta, Eros, Gaspra, and Castalia, are considered. For the case of circular equatorial orbits, the radius for which resonant pitch oscillations are excited, is determined. It is noticed that for slowly rotating large asteroids such as Vesta, more than one resonant region can exist. Stability of pitch motion is significantly affected by the rotational state as well as the shape of the small body. General three-dimensional attitude motion is considered next. Orbits corresponding to large 3D motion are identified. [ABSTRACT FROM AUTHOR]

The work reported here was motivated by the development of manipulator systems comprising one long-reach, flexible-link subsystem, termed the macromanipulator, and a short-reach, rigid-link subsystem, called the micromanipulator. The flexural states of the macromanipulator, needed for controlling such systems effectively, are not usually measurable directly. For this reason, a state-estimation algorithm is proposed which uses the velocity and angular-velocity data of the micromanipulator base to estimate the flexural states of the macromanipulator. The velocity data are inferred from the acceleration signals delivered by a kinematically redundant set of triaxial accelerometers. The accelerometer signals are also utilized to calculate the translational and angular accelerations of the micromanipulator base, which are, in turn, used along with the dynamics equations of the micromanipulator to obtain the reaction force and moment acting between the two subsystems. Treating the force and the moment as inputs, the dynamics equations of the macromanipulator alone are used in the observer, thus reducing the order of the dynamics model. The state-output relations, on the other hand, are linearized in closed form to lower the computational cost. The relations thus obtained are then used in an extended Kalman filter to estimate the flexural states of the system. [ABSTRACT FROM AUTHOR]

The advantages of combining a conventional controller and a knowledge-based approach are addressed in the specific context of regulating a robotic manipulator with deployable and slewing links. A hierarchical structure having a high-speed crisp-algorithmic controller at the bottom layer and an intelligent tuner at an upper layer is developed. The top-level intelligent tuner uses a valid set of linguistic rules for adjusting proportional-integral-derivative servos, based on the theory of fuzzy logic. The behavior of the system is evaluated on the basis of the numerical simulation results as well as experiments with a prototype manipulator system. Results suggest significant improvement in the system performance through the fuzzy logic–based hierarchical control structure. [ABSTRACT FROM AUTHOR]

Background: The short-term course of schizophrenia is reported to be better in some developing country settings. The long-term course in such settings, however, has rarely been studied.Aims: To examine the long-term course and mortality of schizophrenia in patients with a poor 2-year course.Method: The report is based on two incidence cohorts of first-contact patients in urban and rural Chandigarh, India, originally recruited for the World Health Organization Determinants of Outcome of Severe Mental Disorders study. Patients were assessed using standardised instruments at 2- and 15-year follow-ups.Results: Ninety-two per cent of the patients with a poor 2-year course had a poor long-term course and 47% died - a nine times higher mortality rate than among patients with other 2-year course types.Conclusions: In this developing country setting, a poor 2-year course was strongly predictive of poor prognosis and high mortality, raising questions about the adequacy of care for such patients. [ABSTRACT FROM AUTHOR]

Background: This study explored the relation of level of socio-economic development to the course of non-affective psychosis, by extending the analysis of urban/rural differences in course in Chandigarh, India.Method: The proportion of 'best outcome' cases between urban (n = 110) and rural (n = 50) catchment areas were compared at two-year follow-up, separately for CATEGOS+ and non-S+ schizophrenia.Results: The proportion of subjects with 'best outcome' ratings at the urban and rural sites, respectively, was similar for CATEGOS+ schizophrenia (29 v. 29%), but significantly different for non-S+ psychosis (26 v. 47%).Conclusions: The fact that in rural Chandigarh, psychoses have a more favourable course than in the urban area may be explained in large part by psychoses distinct from 'nuclear' schizophrenia. [ABSTRACT FROM AUTHOR]

Studies the attitude control of a system called Tethered Satellite System (TSS) using an order of N Lagrangian formulation. Characteristic of the arbitrary orbit of the system; Information on the conception of TSS by a Russian scientist Tsiolkovsky; List of the possible applications of TSS; Description of the system; Derivation of the system model and formulation; Control around the equilibrium position; Change in platform orientation.