Satish Dhawan Space Center
Satish Dhawan Space Center
Seshubabu K.,Satish Dhawan Space Center |
Jose C.L.,Satish Dhawan Space Center
International Journal on Electrical Engineering and Informatics | Year: 2017
This paper presents a comparison between Sensor or Indirect Field Oriented Control (IFOC) and Sensor-less Field Oriented Control (SFOC) in low frequency region for Induction Motor (IM). These two strategies can be considered among the family of Vector Control (VC) methods and provide a solution for high-performance drives. Most of the Electrically-operated Overhead Travelling (EOT) Crane IMs are controlled with vector control techniques. IM performance will deteriorate as frequency falls below 5 Hz due to its stator resistance drop. There are some critical requirements which needs rocket segments and satellite needs to be positioned in very precise position. For this EOT crane has to run in creep speed which needs drive has to run below 5 Hz. In this paper, the analysis is carried out on IFOC and SFOC methods and implemented to IM drives. In IFOC, flux magnitude and angle is achieved by imposing a slip frequency derived from the rotor dynamic equations with monitored rotor speed using external sensor such as encoder. Whereas SFOC does not require any sensor for estimation of flux magnitude and position, with monitored stator voltages and stator currents, flux magnitude and position can be achieved. Advantages and disadvantages of two control methods are emphasized in low frequency region (0-5 Hz). The theoretical results are found to be consistent with experimental results performed on 100 HP, three phase IM. It is concluded that IFOC method is better than SFOC method in low frequency region. © 2017, School of Electrical Engineering and Informatics. All rights reserved.
Rajeevan M.,National Atmospheric Research Laboratory |
Madhulatha A.,National Atmospheric Research Laboratory |
Rajasekhar M.,Satish Dhawan Space Center |
Bhate J.,National Atmospheric Research Laboratory |
And 2 more authors.
Journal of Earth System Science | Year: 2012
A prediction model based on the perfect prognosis method was developed to predict the probability of lightning and probable time of its occurrence over the south-east Indian region. In the perfect prognosis method, statistical relationships are established using past observed data. For real time applications, the predictors are derived from a numerical weather prediction model. In the present study, we have developed the statistical model based on Binary Logistic Regression technique. For developing the statistical model, 115 cases of lightning that occurred over the south-east Indian region during the period 2006-2009 were considered. The probability of lightning (yes or no) occurring during the 12-hour period 0900-2100 UTC over the region was considered as the predictand. The thermodynamic and dynamic variables derived from the NCEP Final Analysis were used as the predictors. A three-stage strategy based on Spearman Rank Correlation, Cumulative Probability Distribution and Principal Component Analysis was used to objectively select the model predictors from a pool of 61 potential predictors considered for the analysis. The final list of six predictors used in the model consists of the parameters representing atmospheric instability, total moisture content in the atmosphere, low level moisture convergence and lower tropospheric temperature advection. For the independent verifications, the probabilistic model was tested for 92 days during the months of May, June and August 2010. The six predictors were derived from the 24-h predictions using a high resolution Weather Research and Forecasting model initialized with 00 UTC conditions. During the independent period, the probabilistic model showed a probability of detection of 77% with a false alarm rate of 35%. The Brier Skill Score during the independent period was 0.233, suggesting that the prediction scheme is skillful in predicting the lightning probability over the south-east region with a reasonable accuracy. © Indian Academy of Sciences.
News Article | February 17, 2017
India’s Polar Satellite Launch Vehicle lifts off from the Satish Dhawan Space Center on the coast of the Bay of Bengal, sending 104 satellites spaceward. (ISRO Photo) A record-setting flock of 104 satellites was successfully deployed into orbit overnight after the launch of an Indian rocket. Seattle-based Spaceflight Industries played a part in getting nine of those satellites where they needed to go. India’s Polar Satellite Launch Vehicle, or PSLV, lifted off from the Satish Dhawan Space Center at Sriharikota at 9:28 a.m. local time today (7:58 p.m. PT Tuesday). The mission’s main payload was the Indian Space Research Organization’s Cartosat 2D, a car-sized satellite designed for environmental mapping. Another 88 Dove nanosatellites, each about the size of a toaster oven, will become part of Planet’s Earth-observing constellation. Eight more nanosatellites were launched for Spire Global, which is filling out a constellation to monitor weather as well as aviation and maritime traffic. This is the second Spire PSLV mission facilitated by Spaceflight Industries, which handles launch logistics. Spaceflight also arranged to get Israel Aerospace Industries’ BGUSat nanosatellite on the flight. BGUSat is a research spacecraft built by students at Ben Gurion University to perform cloud imaging and measure atmospheric background radiation. Six more research satellites rounded out the flock, which represented the highest number of satellites launched on a single rocket. ISRO said all 104 satellites were successfully deployed into pole-to-pole orbits within a half-hour after launch. The mission marked a numerical milestone for Spaceflight Industries as well as for India’s space effort. “We’ve hit (and passed) the 100-satellite milestone,” Spaceflight said in a pre-launch blog posting. “With this launch, we’ve sent 103 satellites to space since our first one in 2013. The team at Spaceflight is proud of this achievement, and to be part of enabling the growth of commercial enterprises and new science missions in space.” In addition to launch logistics, Spaceflight is building its own spacecraft for its BlackSky Earth-observing constellation. Its first BlackSky Pathfinder satellite was launched on a PSLV rocket last September, and the second Pathfinder is due to be sent into orbit later this year. Eventually, Spaceflight’s BlackSky subsidiary aims to have 60 satellites sending down on-demand imagery from low Earth orbit.
News Article | April 14, 2016
Cartosat-2C, the earth observation satellite of the Indian Space Research Organisation (ISRO), will be launched in May atop a PSLV rocket in hopes of proving the country's military surveillance and reconnaissance capabilities. A successful launch will place India alongside a few select nations, namely the United States, China, and Israel, which have spy satellites watching the planet from space. Cartosat-2C – the younger kin of Cartosat-2A, the country's first military satellite launched in 2007 – was built in Ahmedabad at the Space Applications Center, then brought to Bengaluru at the ISRO Satellite Center after being tested and evaluated. Little is known at present about the satellite, but ISRO is confident it will get the job done. "[It] is expected to provide very high resolution pictures and videos captured from space," an ISR official told Indian Express. The dual-use satellite weighs 690 kilograms (1,521 pounds) and is armed with a Panchromatic Camera as well as a high-resolution multi-spectral instrument. Boasting a resolution of 0.65 meter when its predecessor has only 0.8 meter, this camera is said to capture high-res images of areas and borders of dispute, and log videos of sensitive targets from space and transmit them back to Earth. Panchromatic imagers, too, are deemed useful for disaster monitoring and recording temperatures of specific locations versus surrounding sites. Along with 21 other satellites, Cartosat-2C will be launched aboard a Polar Satellite Launch Vehicle (PSLV) rocket, positioned in orbit at a low-Earth altitude of around 200 to 1,200 kilometers (approx. 124-745 miles) above planetary surface. The Indian space agency is also keen on increasing the number of PSLV flights to ferry more satellites into space and eventually privatize the rocket’s operations. "We want [industries] to form a consortium to build PSLV and launch satellites," ISRO chair A.S. Kiran Kumar said in a Deccan Chronicle report, citing their target of 12 flights a year initially and then scaling it up to 24 annually. The ISRO has started building its second site for PSLV assembly at Satish Dhawan Space Center, which is estimated ready later this year. A day-long conference on April 21 will offer the consortium proposal to executives from more than 25 Indian industries tapped to fly the PSLV. Joining the consortium is viewed as a launchpad for private enterprises to compete in the global aerospace and defense arena filled with billion-dollar contracts. In February, the chief of the French space agency confirmed that they are in talks with India to put a lander on Mars in their own bid to explore the Red Planet. India's Mars Orbiter Mission arrived in the planet's orbit in September 2014 – the country's first ever interplanetary mission, costing $74 million. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.
News Article | February 15, 2017
Stem-cell trial Japan is resuming pioneering clinical research using induced pluripotent stem (iPS) cells. A team led by Masayo Takahashi at the RIKEN Center for Developmental Biology in Kobe will make suspensions of iPS cells derived from retinal cells, and transplant them into people with age-related macular degeneration, an eye condition that can cause blindness. Takahashi started a similar study in 2014 — the first to use iPS cells in humans — but the cells prepared for the second patient were found to have genetic abnormalities and no other participants were recruited. On 1 February, Japan’s health ministry approved a new five-patient study. This time the team will use banked iPS cells created from anonymous, healthy donor cells rather than from the participants themselves. Martian polar ice cap sculpted by wind A seasonal layer of carbon dioxide frost coats Mars’s northern polar ice cap in this image, which was released on 2 February by the European Space Agency (ESA). Each winter, carbon dioxide precipitates out of the cold atmosphere and onto the ice cap. The image is a composite of pictures taken between 2004 and 2010 by ESA’s Mars Express spacecraft. The distinctive spiral troughs were probably carved by wind. Radar investigation by Mars Express and NASA’s Mars Reconnaissance Orbiter revealed that the ice cap consists of many layers of ice and dust extending to a depth of about 2 kilometres. GM wheat trial A UK research laboratory has been granted permission to begin field trials of a wheat plant that has been genetically modified (GM) to improve photosynthesis. Scientists at Rothamsted Research in Harpenden have already shown that wheat plants modified with a gene from stiff brome grass (Brachypodium distachyon) are more efficient at photosynthesis in greenhouses than conventional wheat, and they now hope to see improved yields from plants grown outside in more realistic conditions. In 2012, GM trials at Rothamsted attracted small but high-profile protests. The lab’s researchers have been among the leading advocates of such trials in Europe. Swedish stimulus The Swedish government unveiled plans on 2 February to make the country carbon neutral in less than two decades. A law expected to pass through parliament in March would set a binding target of reducing domestic greenhouse-gas emissions from industry and transport by 85% by 2045, relative to 1990 levels. Remaining emissions would be offset by natural carbon capture through forestation and by investment abroad. On announcing the move, Sweden’s environment minister, Isabella Lövin, said that her country wants to set an example at a time when climate action in the United States is threatening to lose momentum. Romanian protests Angry Romanian scientists have called on their new government to reverse its order for national science-advisory bodies to immediately stop their work, pending reorganization. The government made the order on 31 January, when it also issued a decree giving amnesty to some officials accused of corruption; this was later withdrawn after mass protests. An open letter signed by nearly 600 academics and their supporters says that the councils, which are non-political, should be immune to government change. Signatories fear that the proposed reorganization may allow amnesty for politicians who have committed scientific misconduct. UK science czar The UK government’s chief scientific adviser has been appointed to possibly the biggest science job in the country. The government announced on 2 February that Mark Walport will take the helm of a new body called UK Research and Innovation (UKRI), which is expected to oversee a pot of more than £6 billion (US$7.5 billion) in government science spending when it comes into being in 2018. Walport’s appointment is significant because there are fears that UKRI could reduce the freedom of the nine individual bodies that currently allocate much government science funding. Researcher on trial An Iranian researcher in disaster medicine, who is accused of collaboration with a “hostile government”, has been threatened with the death sentence by a judge on Iran’s revolutionary court, according to close contacts of the scientist. Ahmadreza Djalali, who had been affiliated with research institutes in Italy, Sweden and Belgium, was arrested in April 2016 during an academic visit to Iran. According to sources close to Djalali, he has been kept in solitary confinement for three months in a Tehran prison and was forced to sign a confession. Djalali’s trial is scheduled to start later this month. Ice station The British Antarctic Survey (BAS) announced on 2 February that it had completed moving its Halley VI research station 23 kilometres across the floating ice platform on which it rests. The 13-week operation, which used tractors to tow the station’s 8 modules (pictured), was prompted by fears about a growing crack in the Brunt ice shelf. Staff were evacuated last month for the coming Antarctic winter after another unpredictable crack in the ice was discovered. The base, which is designed to be relocated periodically, is ready for re-occupation in November, the BAS said. Borehole record The Iceland Deep Drilling Project completed the deepest-ever geothermal well on 25 January. After 168 days of drilling, the well bottomed out at 4,659 metres, just shy of its 5-kilometre goal. But temperatures and pressures were so high at the bottom of the well that fluids were observed behaving in a ‘supercritical’ fashion — as neither liquid nor gas — an observation that was one of the project’s goals. The well, on Iceland’s volcanic Reykjanes peninsula, is being used to explore the source of geothermal systems and to see whether supercritical fluids can be tapped as an energy resource. India’s budget Health research, biotechnology and space science are the main beneficiaries of robust budget increases announced by the Indian government on 1 February. Overall, science spending in 2017 by eight ministries (excluding nuclear and defence research) will increase by 11% — well above the projected 5% inflation rate — to 360 billion rupees (US$5.3 billion). Health research, including the fight against diseases such as leprosy and measles, will get 31% more government funding. Biotechnology will get an extra 22%, and India’s aspirations in space, including plans to land a rover on the Moon in 2018, will benefit from a 21% budget increase for space science. Dual tribute The CRISPR gene-editing system, which has transformed biological research and biomedicine, drew yet more major prizes last week. On 31 January, the Madrid-based BBVA Foundation announced that its €400,000 (US$427,000) Frontiers of Knowledge Award in Biomedicine would be shared by Francisco Mojica, Emmanuelle Charpentier and Jennifer Doudna. Mojica discovered the CRISPR repeating DNA sequences that some bacteria use to fight viral infections. Charpentier and Doudna developed the universal CRISPR editing tool — for which they have also won the ¥50-million (US$445,000) Japan Prize, announced on 2 February. They share it with cryptographer Adi Shamir. Women, non-Asian ethnic minorities and disabled people are under-represented in science and engineering in the United States, according to the National Center for Science and Engineering Statistics (NCSES). Women receive about half of all science and engineering degrees but hold less than 30% of jobs in these areas. White men, who in 2015 comprised only 31% of the US population, held nearly half of these jobs. Although female and minority representation has risen, disparities remain. 11–15 February Biophysicists gather in New Orleans, Louisiana, for the Biophysical Society’s 61st annual meeting. go.nature.com/2jtfz17 12–16 February At an international meeting in Queenstown, New Zealand, scientists discuss the latest research in advanced materials and nanotechnology. confer.co.nz/amn8 15 February India’s Polar Satellite Launch Vehicle launches a high-resolution Earth-observation satellite from the Satish Dhawan Space Center in Sriharikota. go.nature.com/2jteerk
Gopalakrishnan V.,Indian Space Research Organisation |
Prasad M.Y.S.,Satish Dhawan Space Center
Proceedings of the International Astronautical Congress, IAC | Year: 2013
The topic of Space Debris in the context of long term sustainability of outer space activities for peaceful purpose, is gaining momentum and raising concerns, due to ever growing human made debris population in outer space. With the increase in the scope of outer space activities driven by vast application areas vis-à-vis increase in number of space-faring nations and related players, the situation warrants certain remediation measures beyond mitigation measures. Cleaning-up of the debris dumped all these years of space activities, is quite imperative. While the concept of Active Debris Removal (ADR), poses many technical challenges in terms of development, demonstration and implementation, it poses certain non-technical challenges to international space community relating to policy aspects, international consensus & collaboration, investment & economic viability and legal issues. Legal challenges include a host of issues such as definitional issues on space debris vis-à-vis space objects, affiliation of ownership and responsibility of space objects/debris originating from 'launching state', 'state-of-registry', abandonment of space objects & debris, liability issues in the course of disposal activities, enforcement of technology controls & safeguards, intellectual property protection, and on so on. The provisions under UN Treaties on outer space activities such as Space Object, Launching State, State responsibility, Liability, Jurisdiction & Control, due regards and avoidance of harmful interference to others space activities, which indirectly address the problems of space debris could be taken support to address the legal issues associated with topic of ADR. Prevailing UN Guidelines on space debris mitigation are to be implemented by states through national policies and regulations on voluntary basis and hence they are non-binding soft law instruments. Nevertheless, some analogy could be drawn from the Law of Sea (Article 60 and Article 80 of UN Convention on the Law of Sea, 1982), and Nairobi International Convention on the removal of wrecks, 2007, which are very much comparable to the responsibility of a launching state or state of registry in respect of their inactive space objects like defunct spacecraft and rocket bodies and components thereof. The economic dimension of the concept and operation of ADR and associated operational liability issues could be addressed through sharing of burden in an equitable manner. The principle of 'polluters pays' could be applied on the basis of Common but Differentiated Responsibility principle, amongst the space faring nations. ADR activities could be facilitated, monitored and governed by an international body under UN arrangement. ©2013 by the International Astronautical Federation. All rights reserved.
News Article | February 21, 2017
India has the ability to develop a space station – yet it’s still unclear whether it will. This is the statement of Indian Space Research Organization chairman A.S. Kiran Kumar at the foundation day ceremonies of the Raja Ramanna Center for Advanced Technology in the country on Monday, Feb. 20. According to Kumar, they are still in talks about the immediate benefits of a manned space mission, citing the need for funds and time as to why the country has not decided on when to invest on a space station. “The day the country takes the decision, we will ‘ok’ the project,” he said in an India Times report, emphasizing that the project requires long-term thinking along with policy and funding support. A space station is a crewed satellite that is designed to stay in low Earth orbit for long periods of time, studying the results and consequences of long-term spaceflight in humans. Today only one space station is operating: the International Space Station, a joint effort of NASA, Russia, and the European Union. Kumar added that the Indian space agency was also considering partnering with the private space sector to enhance its satellite-launching ability, and mentioned the need to up the number of satellites that monitor land and weather conditions in India and fortify its communication network. He pointed to a need to conduct about 18 launches every year, or triple its current capacity. In a commentary, LiveMint pointed to why ISRO managed to deliver on such groundbreaking level that few other government agencies of its kind was able to. “ISRO’s current chairman, A.S. Kiran Kumar, is also chairman of the Space Commission and secretary of DOS [Department of Space]. This setup has promoted vertical integration between policymakers — who are in a position to understand the nature of the long-term projects ISRO undertakes — and those delivering the end results,” the publication noted. ISRO is fresh from the success of its record-breaking 104-satellite launch aboard a single rocket. Last Feb. 15, it launched the rocket from Sriharikota's Satish Dhawan Space Center in Andhra Pradesh. The Polar Satellite Launch Vehicle-C37 carried a payload of 103 nano-satellites coming from India as well as Kazakhstan, Israel, the United States, the Netherlands, and Switzerland. It also transported the Earth observation instrument Cartosat-2. No other nation has so far launched 104 satellites from a single rocket in one go, making the feat a huge and important one for ISRO. The Russian space agency Roscosmos held the previous record at 37 satellites in one rocket launch. India also hiked its spending on space technology and research, believing that space exploration investments will yield positive returns for the country. It is mostly gearing up for two missions, each leading to Mars and Venus, with the Mars Orbiter Mission II possibly including a lander and likely to launch in 2021. India’s Mars Orbiter Mission arrived in the planet’s orbit back in September 2014, its first-ever interplanetary mission that came with a $74 million price tag. The nation finds a Mars mission rival in its Asian neighbor China, which aims to send a Mars probe by 2020 after a probe on the far side of the moon by late 2018. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.
PubMed | National Institute of Technology Warangal, Satish Dhawan Space Center, Institute of Chemical Technology, Rashtrasant Tukadoji Maharaj Nagpur University and University of Melbourne
Type: | Journal: Ultrasonics sonochemistry | Year: 2017
The present work reports on an efficient and simple one pot synthetic approach for aluminium nanoflakes and nanoparticles based on the intensification using ultrasound and provides a comparison with the conventional approach to establish the cutting edge process benefits. In situ passivation of aluminium particles with oleic acid was used as the method of synthesis in both the conventional and ultrasound assisted approaches. The aluminium nanoflakes prepared using the ultrasound assisted approach were subsequently dispersed in di-octyl adipate (DOA) and it was demonstrated that a stable dispersion of aluminium nanoflakes into di-octyl adipate (DOA) is achieved. The morphology of the synthesized material was established using the transmission electron microscopy (TEM) analysis and energy dispersive X-ray analysis (EDX) and the obtained results confirmed the metal state and nano size range of the obtained aluminium nanoflakes and particles. The stability of the aluminium nanoflakes obtained using ultrasound assisted approach and nanoparticles using conventional approach were characterized using the zeta potential analysis and the obtained values were in the range of -50 to +50mV and -100 to +30mV respectively. The obtained samples from both the approaches were also characterized using X-ray diffraction (XRD) and particle size analysis (PSA) to establish the crystallite size and particle distribution. It was observed that the particle size of the aluminium nanoflakes obtained using ultrasound assisted approach was in the range of 7-11nm whereas the size of aluminium nanoparticles obtained using conventional approach was much higher in the range of 1000-3000nm. Overall it was demonstrated that the aluminium nanoflakes obtained using the ultrasound assisted approach showed excellent morphological characteristics and dispersion stability in DOA showing promise for the high energy applications.
News Article | November 14, 2016
Spaceflight Industries, a next-generation space company enabling access to space and redefining global intelligence, has revealed some of the first photos captured by its BlackSky Pathfinder-1 satellite Pathfinder-1 was launched on September 26 from Satish Dhawan Space Center in Sriharikota, India. Additional images from Pathfinder-1 can be found on the BlackSky blog. "The preliminary results we've achieved thus far have fulfilled our expectations and point to the magnitude at which BlackSky's 60-satellite constellation will be able to inform global decision-making," said Jason Andrews, chief executive officer of Spaceflight Industries. "Through Pathfinder-1, which has been a total success, we have proven out our overall business plan and system architecture, and are on track to revolutionize our understanding of the world." Spaceflight Industries built and launched Pathfinder-1 and also operates the spacecraft with its command and control system, which includes ground stations and constellation management software. Weighing in at 50 kg and costing under $10M to build and launch, Pathfinder-1 represents a revolution in spacecraft size, cost and performance. The spacecraft is equipped with a SpaceView 24™ imaging telescope, built by Harris Corporation (NYSE:HRS), allowing it to image an area approximately 30 square kilometers at high resolution. Following launch, the Spaceflight Industries' operations team has conducted extensive spacecraft level testing and is currently in the process of working through payload calibration as well as transitioning to automated operations. Pathfinder-1 is presently operating in a 690 km circular orbit because it was launched as a rideshare spacecraft, while the BlackSky constellation will operate at 450 km. Andrews added, "Even at this altitude we are pleased with the detail and performance, which validates our ability to look at major drivers of our economy. Each Pathfinder-1 image has millions of pixels and captures an area that is 10 km across. Poking around the planet and looking at whatever you want, when you want, is a powerful thing." Images from Pathfinder-1 and the follow-on 60-satellite BlackSky constellation will provide a rapid revisit rate with the ability to pass over key zones hourly, making images fresher and at an unmatched low cost of approximately $90 per image. Pathfinder-1 will be joined by Pathfinder-2, which is scheduled to launch in early 2017, to expand system demonstrations and technology validation. Spaceflight Industries is enabling timely and affordable access to space while redefining how we observe our planet in real time. Through its services Spaceflight and BlackSky, the company offers innovative satellite design, rideshare launch management, global communications networking, and a geospatial intelligence platform to support a new era of global awareness. Founded in 1999, the Seattle-based company has a well-earned track record of success on a global scale. Visit www.spaceflight.com or www.blacksky.com for more information. Please follow SpaceRef on Twitter and Like us on Facebook.
Verma P.,Allahabad University |
Verma P.,Satish Dhawan Space Center |
Manoj G.S.,Satish Dhawan Space Center |
Pandey A.C.,Allahabad University
Physica B: Condensed Matter | Year: 2010
Driven with an objective of confining the growth of nanoparticles, polyvinyl pyrrolidone (PVP) was used as a capping agent over Mn+2-doped CdS nanoparticles. The mechanism is studied and results are discussed. An improvement in the doping efficiency and improvement in reproducibility of the nanoparticles as compared to the common co-precipitation method is observed which can be endorsed to the introduction of PVP, as coordination of PVP molecular orbitals with metallic orbitals attribute to the surface passivation of the CdS nanoparticles. PVP helps in stabilizing the nanoparticles, increases the doping efficiency and leads to enhancement in optoelectronic properties. A change in band gap is noticed as there is blue shift in wavelength compared to bulk due to confinement of particle size. The obtained nanoparticles are characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible and photoluminescence spectroscopy. © 2009 Elsevier B.V. All rights reserved.