Attitude Control and Consensus on SO(3) Using Sinusoids: Theory and Application to Small Satellites

We present and analyze kinematic-level and dynamic-level feedback control algorithms for single agent attitude control and multi-agent attitude consensus on SO(3). The kinematic-level algorithms yield attitude feedback controls that are piecewise-continuous sinusoidal angular velocities. The dynamic-level algorithms yield attitude feedback controls that are relative angles of rotational-mass actuators, which are continuous but only piecewise continuously differentiable sinusoids. Furthermore, the dynamic-level algorithms are designed to accommodate actuator stroke constraint. We present application of the dynamic-level control algorithms to attitude control and consensus of small-satellites

Impacts of project management on real option values

The cost of construction projects depends on their size, complexity, and duration. Construction management applies effective management techniques to the planning, design, and construction of a project from conception to completion for the purpose of controlling time, cost and quality. A real options approach in construction projects, improves strategic thinking by helping planners recognize, design and use flexible alternatives to manage dynamic uncertainty. In order to manage uncertainty using this approach, it is necessary to value the real options. Real option models assume independence of option holder and the impacts of underlying uncertainties on performance and value. The current work proposes and initially tests whether project management reduces the value of real options. The example of resource allocation is used to test this hypothesis. Based on the results, it is concluded that project management reduces the value of real options by reducing variance of the exercise signal and the difference between exercise conditions and the mean exercise signal

Mary Shelley’s Frankenstein: A Treatise of Science

191-200Mary Wollstonecraft Godwin Shelley’s Frankenstein (1818) is a critique of science and its experiments. It is a thoughtful comment on the terrifying consequences of scientific experimentation with life. It is grounded on a specific research, namely, that of creating life in the laboratory without a mother’s womb. It predicts the modern researches on cloning, and more than anything else, Frankenstein criticizes the way some scientists have been trying to control nature. Mary Shelley’s emphasis is not so much on the research itself as on some ethical issues that emerge from that research. And those ethical issues have not yet lost their social implications. Frankenstein has become a cultural myth of the modern world and has provided us with a metaphor for the potentially disastrous results of thoughtless scientific aims because it raises some ethical issues as to the limits of a scientist’s interference with nature. It is an extrapolation of current science and technology and its effects on future worlds, both living and non-living. It gave a wake-up call to scientists and others particularly decision makers to awaken a new consciousness of the true realities inherent in the positive and negative potentialities of science and technology. It is a revelation of what is in store for humanity if science and technology is immorally or irresponsibly used. Frankenstein is a pioneering and powerful treatise on the responsibilities and values of science with a thought-experiment: a thoughtless research very much leads towards diabolic effects

“Field Weakening Operation of AC Machines for Traction Drive Applications.”

The rising cost of gasoline and environmental concerns have heightened the interest in electric/hybrid-electric vehicles. In passenger vehicles an electric traction motor drive must achieve a constant power speed range (CPSR) of about 4 to 1. This modest requirement can generally be met by using most of the common types of electric motors. Heavy electric vehicles, such as tanks, buses and off-road equipment can require a CPSR of 10 to 1 and sometimes much more. Meeting the CPSR requirement for heavy electric vehicles is a significant challenge. This research addresses the CPSR capability and control requirements of two candidates for high CPSR traction drives: the permanent magnet synchronous motor (PMSM) and the switched reluctance motor (SRM). It is shown that a PMSM with sufficiently large winding inductance has an infinite CPSR capability, and can be controlled using a simple speed control loop that does not require measurement of motor phase currents. Analytical and experimental results confirm that the conventional phase advancement method charges motor winding with required current to produce the rated power for the speed range where the back-EMF normally prevents the generation of the rated power. A key result is that for the PMSM, the motor current at high speed approaches the machine rating independent of the power produced. This results in poor partial load efficiency. The SRM is also shown to have infinite CPSR capability when continuous conduction is permitted during high speed operation. Traditional high speed control is of discontinuous type. It has been shown that this discontinuous conduction itself is the limiter of CPSR. Mathematical formulas have been developed relating the average current, average power, and peak current required producing the desired (rated) power to machine design parameters and control variables. Control of the SRM in the continuous conduction mode is shown to be simple; however, it does require measurement of motor current. For the SRM the motor current at high speed is proportional to the power produced which maintains drive efficiency even at light load conditions

Quantification of Dynamic Parameters of Flexible Rotor Partially Levitated on Active Magnetic Bearing

An unavoidable fault that generally present in the rotor system is residual unbalance, and plenty of research has been carried out to develop off-line balancing techniques in the past. But, as present industrial need is moving towards a very high speed (supercritical) and light weight drivelines, it is important to use on-line balancing techniques instead of off-line balancing. Therefore, present work is focused on the on-linebalancing of a rotor system by estimating the distributed unbalance parameters with the help of active magnetic bearings (AMBs). The flexible rotor model having helicallydistributed unbalances along its length and supported by two conventional bearing at both ends is well thought-out here for the analysis. Two active magnetic bearings are considered to generate controlling force for suppressing the unbalance. Then, an equivalent discretized modelis formulated by utilizing seven numberof mass-less thin discs having an eccentricity equivalent to distributed unbalance in theflexible rotor.The finite element approachhas been used to obtain a unified model. In the present work, an identification algorithm has been developed to estimate unbalance parameters in addition with dynamic parameters of bearings i.e. conventional as well as AMBs. Equation of motion of the system hasbeen derived by considering only linear DOFs at bearing locations as generalized coordinates. Displacement at various nodes as well as current signals at AMB locations are calculated by using MATLAB Simulink. Since the present proposed algorithm requires frequency domain data to estimate unknown parameters, the time domain signal obtained from Simulink has been transformed into frequency domain by using Fast Fourier Transformation (FFT). The proposed algorithm is developed on the premise of the least-squares fit method in the frequency domain. Fourth order Runge-Kutta solver is used during numerical simulation. Gyroscopic effect has been neglected in the present work

Love-Hate Relationship among SF, Science & Technology

209-220Science fiction is a form of literature that has grown out of a rapidly changing society, due to the advent of modern science and technology. Science does not just mean the exact sciences like physics, chemistry and the like, for it is also a way of looking at life clearly with the eyes of observation and rational judgment. Scientific education is that education that implants a rational, experimental and sceptical frame of mind and is not just a body of knowledge to be taught inside classrooms and laboratories.   The science in science fiction can be real, extrapolated, thought experimented, imaginary, controversial and sometimes just plainly fictional. Almost all branches of science have been employed, used and fictionalized effectively by science fiction writers. The 19th century science fiction primarily was inspired by chemistry, 20th century science fiction was focused on physics, and 21st century science fiction is focusing on biology, biotechnology, genetic engineering and social and human sciences as well. Often, science fiction does what science cannot. In this sense it has become a useful tool for enlightening society. Science fiction is essentially a literary work and not a branch of science

ANTIMICROBIAL POTENTIAL OF FUNGAL ENDOPHYTES ISOLATED FROM LEAVES OF PROSOPIS JULIFLORA (SW.) DC. AN IMPORTANT WEED

Objective: To evaluate the antimicrobial potential of fungal endophytes isolated from leaves of Prosopis juliflora against the important plant and human pathogenic bacteria and fungi.Methods: Antimicrobial screening was done by agar diffusion and dual culture method. The ethyl acetate extract of the endophytes which recorded good activity were subjected to disc diffusion assay and determination of MIC.Results: A total of 446 fungal isolates were recovered from 400 leaflet segments representing 44 fungal endophytes. Species of Cladosporium, Colletotrichum and Fusarium were the dominant genera. Seventeen endophytic fungi out of 44 showed significant antibacterial activity against one or more test bacteria. Ethyl acetate extract of Colletotrichum gloeosporioides exhibited highly significant broad spectrum antibacterial activity. Eleven endophytes showed antifungal activity against all test fungi. Paecilomyces lilacinus and Trichoderma sp. showed significant antifungal activity with growth inhibition of 50% and above in dual culture. The ethyl acetate extract of Paecilomyces lilacinus also showed significant antifungal activity in disc diffusion. This is the first report of antimicrobial potential of the endophyte Paecilomyces lilacinus. Preliminary biochemical characterization of the active ethyl acetate extract of Colletotrichum gloeosporioides and Paecilomyces lilacinus showed the presence of alkaloids, carbohydrates, sterols and coumarins.Conclusion: Results of the study paves the way for further studies on the isolation and characterization of antimicrobial principles and their evaluation for the agricultural and medical application.Â

Seasonal diversity & spaciotemporal distribution of fungal endophytes associated with the medicinal plant Coleus forskohlii Briq.

Fungi that colonize the healthy tissues of the plants without showing any disease symptoms in the host plants are termed as fungal endophytes. The presence of fungal endophytes provides a positive effect on the host’s growth & development and also triggers the production of some essential bioactive compounds in the host. This study was undertaken to isolate, identify and understand the spaciotemporal distribution and seasonal diversity of fungal endophytes associated with the leaf, stem & root of Coleus forskohlii, an important and endangered medicinal plant. Sampling was done for a period of 12 months between May 2020–April 2021. A total of 950 fungal endophytes were isolated from a total of 1680 tissues of the leaf, stem & root of C. forskohlii. The fungi were identified based on their morphological features and some of them were identified by molecular identification by 18S rRNA sequencing. The endophytic isolates belonged to 10 different orders belonging to 3 different classes-Sordariomycetes (Hypocreales, Xylariales, Microascales, Trichosphaeriales, Glomerellales & Sordariales), Dothiomycetes (Pleosporales, Capnodiales, Botryosphaeriales) & Eurotiomyctes (Eurotiales). About 81.26% of the isolates belonged to Ascomycota & 2.63% of the isolates belonged to Mucoromycota. Chaetomium globosum, Collariella bostrychodes, C. robusta, Colletotrichum gloeosporioides, Fusarium chlamydosporum, Sterile hyaline mycelia, Aspergillus niger, Xylaria curta, X. grammica, Mucor circinelloides & Trichoderma harizianum were the frequently isolated species of fungi. C. globosum, C. bostrychodes, C. gloeosporioides, sterile hyaline mycelia &  X. curta were found distributed in all the tissues of the plant. C. forskohlii has thus revealed a rich diversity of fungal endophytes that could be isolated & cultured to yield some pharmacologically important bioactive compounds

Isolation, identification and screening of potential cellulase-free xylanase producing fungi and its production

In order to isolate cellulase-free xylanase producing fungi, screening and isolation was done using composting soil as microbial source. Eight fungal species were selected for further study based on clearing zones formation on agar media containing covalently linked xylan with dye cibacron brilliant red-3BA. Both solid state and submerged fermentations were done with eight fungal isolates to identify strain that could produce highest amount of cellulase-free xylanase at a pH of 5.5 and at 28 ± 2°C temperature. Under solid state conditions, 50% of the strains produced xylanase (45.78 to 923 U gds-1) and lower amount of cellulase (20 to 33 U gds-1). The amount of soluble protein was also determined which ranged between 67 to 99 mg gds-1. In submerged conditions, 25% strains produced xylanase (45 to 205 U mL-1) and negligible amount of cellulase (12 to 13 U mL-1). The amount of soluble protein was determined which ranged between 45 and 85 U ml-1 in submerged conditions. Growth was determined in terms of mycelial dry weight which ranged between 0.70 and 2.90 mg mL-1.Keywords: Cellulase-free xylanase, xylan, solid state fermentation, submerged fermentatio

An Ayurveda Review on Shothahara Mahakashaya Dravya and their Therapeutic Properties

Shothahara Mahakashaya refers to a collection of medicinal ingredients that exhibit therapeutic effects against Shotha Roga. Shotha is a condition characterized by swelling anywhere in the body, which can be equated with the term oedema in modern medicine. Acharya Charak has delineated Shothahara Mahakashaya as one of the group among the fifty Mahakashaya Ganas. The components comprising Shothahara Mahakashaya are Patala, Bilva, Shyonaka, Agnimantha, Kashmariya, Brihati, Shalaparni, Kantakari, Prishaniparni and Goksura. These plants, offer potent effect in its own right, while acts synergistically when combined to produce enhanced therapeutic outcomes. They share common characteristics such as having a Katu, Tikta and Kashaya Rasa, Ushna Virya, Katu Vipaka, Ruksha-Laghu Guna and Tridoshaghna properties. These properties contributed towards the Shothahara effect of these drugs. This article presented a review on Shothahara Mahakashaya Dravya and their therapeutic properties