Nanoscale Structure and Elasticity of Pillared DNA Nanotubes

We present an atomistic model of pillared DNA nanotubes (DNTs) and their elastic properties which will facilitate further studies of these nanotubes in several important nanotechnological and biological applications. In particular, we introduce a computational design to create an atomistic model of a 6-helix DNT (6HB) along with its two variants, 6HB flanked symmetrically by two double helical DNA pillars (6HB+2) and 6HB flanked symmetrically by three double helical DNA pillars (6HB+3). Analysis of 200 ns all-atom simulation trajectories in the presence of explicit water and ions shows that these structures are stable and well behaved in all three geometries. Hydrogen bonding is well maintained for all variants of 6HB DNTs. We calculate the persistence length of these nanotubes from their equilibrium bend angle distributions. The values of persistence length are ~10 {\mu}m, which is 2 orders of magnitude larger than that of dsDNA. We also find a gradual increase of persistence length with an increasing number of pillars, in quantitative agreement with previous experimental findings. To have a quantitative understanding of the stretch modulus of these tubes we carried out nonequilibrium Steered Molecular Dynamics (SMD). The linear part of the force extension plot gives stretch modulus in the range of 6500 pN for 6HB without pillars which increases to 11,000 pN for tubes with three pillars. The values of the stretch modulus calculated from contour length distributions obtained from equilibrium MD simulations are similar to those obtained from nonequilibrium SMD simulations. The addition of pillars makes these DNTs very rigid.Comment: Published in ACS Nan

Method and system to perform energy-extraction based active noise control

A method to provide active noise control to reduce noise and vibration in reverberant acoustic enclosures such as aircraft, vehicles, appliances, instruments, industrial equipment and the like is presented. A continuous-time multi-input multi-output (MIMO) state space mathematical model of the plant is obtained via analytical modeling and system identification. Compensation is designed to render the mathematical model passive in the sense of mathematical system theory. The compensated system is checked to ensure robustness of the passive property of the plant. The check ensures that the passivity is preserved if the mathematical model parameters are perturbed from nominal values. A passivity-based controller is designed and verified using numerical simulations and then tested. The controller is designed so that the resulting closed-loop response shows the desired noise reduction

Spacecraft Stabilization and Control for Capture of Non-Cooperative Space Objects

This paper addresses stabilization and control issues in autonomous capture and manipulation of non-cooperative space objects such as asteroids, space debris, and orbital spacecraft in need of servicing. Such objects are characterized by unknown mass-inertia properties, unknown rotational motion, and irregular shapes, which makes it a challenging control problem. The problem is further compounded by the presence of inherent nonlinearities, signi cant elastic modes with low damping, and parameter uncertainties in the spacecraft. Robust dissipativity-based control laws are presented and are shown to provide global asymptotic stability in spite of model uncertainties and nonlinearities. It is shown that robust stabilization can be accomplished via model-independent dissipativity-based controllers using thrusters alone, while stabilization with attitude and position control can be accomplished using thrusters and torque actuators

Robust control of nonlinear flexible multibody systems using quaternion feedback and dissipative compensation

Global asymptotic stability of a class of nonlinear multibody flexible space structures under dissipative compensation is established. Two cases are considered. The first case allows unlimited nonlinear motions of the entire system and uses quaternion feedback. The second case assumes that the central body motion is in the linear range although the other bodies can undergo unrestricted nonlinear motion. The stability is proved to be robust to the inherent modeling nonlinearities and uncertainties. Furthermore, for the second case, the stability is also shown to be robust to certain actuator and sensor nonlinearities. The stability proofs use the Lyapunov approach and exploit the inherent passivity of such systems. The results are applicable to a wide class of systems, including flexible space structures with articulated flexible appendages

Three-axis stabilization of spacecraft using parameter-independent nonlinear quaternion feedback

This paper considers the problem of rigid spacecraft. A nonlinear control law which uses the feedback of the unit quaternion and the measured angular velocities is proposed and is shown to provide global asymptotic stability. The control law does not require the knowledge of the system parameters, and is therefore robust to modeling errors. The significance of the control law is that it can be used for large-angle maneuvers with guaranteed stability

Robust Stabilization of a Class of passive Nonlinear Systems

The problem of feedback stabilization is considered for a class of nonlinear, finite dimensional, time invariant passive systems that are affine in control. Using extensions of the Kalman-Yakubovch lemma, it is shown that such systems can be stabilized by a class of finite demensional, linear, time-invariant controllers which are strictly positive real in the weak or marginal sense. The stability holds regardless of model uncertainties, and is therefore, robust

A Study on the Challenges Regarding Conservation of Water Resources in Rajasthan

Water can not be produced but conserving water is equivalent to production of water. Rajasthan has worked on two side water conservation theories. (i) Supply side (ii) Demand side water Supply Side Water Conservation Activities;- Harvesting the available surplus rainfall runoff by Efficient use of existing resources ,Water Harvesting, Artificial Ground water recharging,Increase in use of treated water,Demand Side Water Conservation Activities;- Various interventions taken for demand side water conservations are as under Diversification in cropping pattern,Micro irrigation system,IEC activities to use water optimally

An Overview on Patient-Centered Clinical Services

Drug-related problems (DRPs) had often been a concern in the system that needed to be detected, avoided, and addressed as soon as possible. The need for a clinical pharmacist becomes even more important. He is the one who can not only share the load but also be an important part of the system by providing required advice. They fill out the patient's pharmacotherapy reporting form and notify the medical team's head off any drug-related issues. General practitioners register severe adverse drug reactions (ADRs) yearly. As a result of all of this, a clinical pharmacist working in and around the healthcare system is expected to advance the pharmacy industry. Its therapy and drugs can improve one's health quality of life by curing, preventing, or diagnosing a disease, sign, or symptom. The sideshows, on the other hand, do much harm. Because of the services they offer, clinical pharmacy has grown in popularity. To determine the overall effect and benefits of the emergency department (ED) clinical pharmacist, a systematic review of clinical practice and patient outcomes will be needed. A clinical pharmacist's anatomy, toxicology, pharmacology, and medicinal chemistry expertise significantly improves a patient's therapy enforcement. It is now important to examine the failure points of healthcare systems as well as the individuals involved

Machinability aspects in dry turning of Ti6Al4V alloy with HiPIMS coated carbide inserts

533-541Owing to their unique mechanical properties, titanium alloys have been and will be used extensively in a myriad of industries ranging from aerospace to automotive to medical field. Hence, a continuous improvement in the performance of the coated inserts with hard materials capable of enhanced tribological and wear resistive properties is necessary. The present work contributes to investigation of the influence of cutting parameters in turning operations of the alpha-beta titanium alloy- Ti-6Al-4V. Tungsten carbide inserts of K20 grade is coated with TiAlN and AlCrN monolayer coatings by high power impulse magnetron sputtering (HPPMS). Machinability of Ti6Al4V alloy is studied at different cutting speed, feed ranging from 60 to 120 m/min and 0.1 to 0.25 mm/rev with constant depth of cut of 0.5 mm to evaluate the optimum turning parameters under dry environment. The tool wear is observed initially under an optical microscope and nature of wear is observed with scanning electron microscope (SEM). It is witnessed that the AlCrN coated inserts have an upper edge over the TiAlN coated inserts due to better adhesion and thermal stability of the coating. Tool wear and surface finish is found to be optimum at cutting speed of 100 m/min, feed of 0.1mm/rev and depth of cut 0.5 mm. The present will provide useful and economic machining solutions for the high speed machining of titanium alloys by effective utilization of coated tungsten carbide inserts

A class of stabilizing controllers for flexible multibody systems

The problem of controlling a class of nonlinear multibody flexible space systems consisting of a flexible central body to which a number of articulated appendages are attached is considered. Collocated actuators and sensors are assumed, and global asymptotic stability of such systems is established under a nonlinear dissipative control law. The stability is shown to be robust to unmodeled dynamics and parametric uncertainties. For a special case in which the attitude motion of the central body is small, the system, although still nonlinear, is shown to be stabilized by linear dissipative control laws. Two types of linear controllers are considered: static dissipative (constant gain) and dynamic dissipative. The static dissipative control law is also shown to provide robust stability in the presence of certain classes of actuator and sensor nonlinearities and actuator dynamics. The results obtained for this special case can also be readily applied for controlling single-body linear flexible space structures. For this case, a synthesis technique for the design of a suboptimal dynamic dissipative controller is also presented. The results obtained in this paper are applicable to a broad class of multibody and single-body systems such as flexible multilink manipulators, multipayload space platforms, and space antennas. The stability proofs use the Lyapunov approach and exploit the inherent passivity of such systems