A Novel Semi-Active Suspension System for Automobiles Using Jerk-Driven Damper (JDD)

With the new advancements in the vibration control, the control strategies for the controllable semi-active dampers are finding their way as an essential part of vibration isolators, particularly in vehicle suspension systems. An analysis of frequency response for single degree of freedom (1DOF) system gives an attribute to the fact that in a semi-active suspension system, the damping coefficients can be adjusted to improve ride comfort and road handling performances. The systems study includes various type of semi-active suspension systems, employing nonlinear magnetorheological(MR) dampers that are controlled to provide improved vibration isolation. The currently available control strategies for semi-active dampers can be divided into two main groups. The first one is `On-Off' control and second one is `continuous' control of variable dampers. Available control strategies are either proportional to the relative velocity of sprung mass or the acceleration of sprung mass. A new control strategy which is proportional to the jerk produced in sprung mass called Jerk Driven Damper (JDD) is proposed and analyzed by the use of two state 'On-Off' damper. The control strategy for 'JDD' system is extremely simple and it involves very common logic. `JDD' system requires a two state controllable damper and jerk sensor. A brief study on controllable damper and jerk sensors are presented in this thesis

Encapsulated somatic embryos of grape (Vitis vinifera L.): An efficient way for storage and propagation of pathogen-free plant material

Cotyledonary-stage somatic embryos (5-7 mm in length) originating from leaf explants of grape (Vitis vinifera L.) cv. Pusa seedless were encapsulated individually in 2 % alginate gel. The encapsulated somatic embryos (ESEs) germinated successfully on 0.7 % agar medium containing B5 macrosalts (half strength), MURASHIGE and SKOOG microsalts (full strength), 3 % sucrose and 2.9 μM gibberellic acid. The percentage of germination of ESEs was higher than that of nonencapsulated somatic embryos (NSEs) of the same size on the same medium. The percent germination of ESEs increased (69.2 ±2.8) on medium supplemented with quarter strength B5 macrosalts. Of the germinating ESEs, 36 % developed into plantlets. Abscisic acid at 0.004 and 0.02 μM had no significant influence on the frequency of germination and plantlet development, however resulted in a 4-week delay in germination. Transferring the embryos onto the full-strength B5 medium containing sucrose and ABA (0.04 μM) for 4-6 weeks prior to encapsulation resulted in extended storage of up to 90 d without loss of the germination potential and the capacity to regenerate into plantlets. Normally developed plantlets regenerated from ESEs were successfully adapted to soil.

Expression of a rice chitinase gene enhances antifungal potential in transgenic grapevine (Vitis vinifera L.)

To enhance the antifungal potential of grapevine, transgenic plants were generated by transferring rice chitinase gene under a maize-ubiquitin promoter along with its first intron into the leaf disc-induced somatic embryos via Agrobacterium mediated transformation. After co-cultivation for 2 days with recombinant Agrobacterium, somatic embryos were transferred onto WPM medium containing BAP 1.5 μM and NAA 0.1 μM supplemented with 25 mg/L hygromycin. Secondary or tertiary embryos were selected and the antibiotic resistant transgenic plantlets were analyzed. The integration and stability of the transgene were confirmed by PCR, RT-PCR, Southern blotting and by Western blot analyses. The transgenic plants exhibited higher chitinase activity than the non-transformed plants. These analyses indicated that the foreign gene was translated into the protein of expected molecular weight that showed chitinase activity. Following in vitro inoculation of powdery mildew (Uncinula necator), the transgenic plants showed delayed onset of the disease and smaller lesions. The transgenic plants were adapted to the greenhouse and did not show any phenotypic alterations.

A New Semi-Active Suspension System Based on Jerk Driven Damper (JDD) Control

A new control strategy for semi-active suspension system in a road vehicle called Jerk Driven Damper (JDD) is proposed and analyzed in this paper. The control strategy for JDD system is extremely simple and it involves very common logic. JDD system requires a two state controllable damper and jerk sensor. A semi-active damper is incorporated into a single degree of freedom (1DOF) quarter car model subjected to base excitation. Here, two types of positive amplitude half sinusoidal type speed breakers (severe and smooth) with same height are considered as input to the vehicle. These proposed road inputs are used for study and simulation of passive, sky-hook (SH) control and acceleration driven damper (ADD) suspension systems. The optimality of JDD is examined over SH and ADD control which is observed with both ‘severe’ and ‘smooth’ speed breakers. It is shown that the JDD control shows better reduction in vertical acceleration when the vehicle comes across severe breaker. Later the vertical body acceleration response (comfort objective) of JDD control strategy is compared with various types of well-studied control strategies and shown to have better isolatio

Sustainable cooling strategies to reduce tool wear, power consumption and surface roughness during ultrasonic assisted turning of Ti-6Al-4V

Issues related to the machinability of difficult-to-machine materials such as Titanium and Nickel base superalloys are well explicated in the literature. In this regard, a novel study, applying ultrasonic vibration along with MQL and LCO2, is proposed to enhance the machinability of Ti-6Al-4V. In this regard, this article attempts to analyze machinability of Ti-6Al-4V in conventional and Ultrasonic Assisted Turning (UAT) under dry, wet, MQL and LCO2. The experiments are performed on an in-house developed ultrasonic assisted turning setup, keeping all the machining parameters constant. The main tool wear mechanisms observed are diffusion, adhesion, abrasion, and built-up edge formation in both cutting strategies. Moreover, the LCO2 and ultrasonic vibration significantly reduce specific cutting energy without compromising the surface roughness and tool life. Ultimately, the LCO2, along with ultrasonic assisted turning, promotes sustainability in the machining of Ti-6Al-4V

Percutaneous vertebroplasty: An experience of 31 procedures

A prospective study of 31 percutaneous vertebroplasty procedures (PVP) in 22 patients treated during January 2000 to December 2001 is presented. PVP was performed using polymethylmethacrylate (PMMA) to treat vertebral collapse due to osteoporosis and vertebral metastasis, to obtain analgesia and spinal stabilization. We analyze the efficacy and complications related to the procedure. PVP is a safe, effective and a daycare surgery. It can be performed under local anesthesia and has minimal and manageable complications