Analysis of ITU-R Performance and Characterization of Ku Band Satellite Downlink Signals during Rainy Season over Chennai Region of India

In this paper, we present the analysis of Ku band Satellite signal reception during rainy season over Chennai region, India (Latitude: 12° 56' 60 N, Longitude: 80° 7' 60 E). We also examine the effectiveness of International Telecommunication Union – Radio communication (ITU-R) model in predicting the rainfall induced attenuation in Ku band, over this region. An improved Simulink model for Digital Video Broadcast – Satellite (DVB-S2) downlink channel incorporating rain attenuation and Cross Polarization Discrimination (XPD) effects is developed to study the rain attenuation effects, by introducing the experimental data in the ITU-R model pertaining to that region. Based on the improved model, a Monte Carlo simulation of the DVB–S2 signal link is carried out and the performance is analyzed by received constellation and Bit Error Rate (BER) parameters

The Transmission of Exchange Rate Changes to Agricultural Prices

Movements in countries’ exchange rates can substantially change the prices of goods faced by producers and consumers and thereby affect incentives to produce, consume, and trade goods. Exchange rate changes, however, might not be completely transmitted (passed through) to domestic prices. Empirical evidence shows that price and exchange rate transmission for agricultural products is low in most developing economies, partly because of trade policies but also because of inadequate infrastructure and other market deficiencies. During the last 20 years, developed and developing countries generally have moved away from support policies that impede price and exchange rate transmission toward trade policies that allow transmission, such as tariffs. The Uruguay Round Agreement on Agriculture of 1994 strongly encouraged this development. Despite these policy changes, market deficiencies remain as a cause of incomplete transmission. Incomplete transmission weakens countries’ integration into world agricultural markets and thereby reduces agricultural trade potential. Low transmission in developing countries also decreases their own benefits from trade, including the gains they could realize if there is further global agricultural liberalization.Agricultural infrastructure, agricultural policy, agricultural trade, exchange rates, exchange rate transmission, imperfect markets, institutions, price transmission., Agribusiness, Agricultural and Food Policy, Agricultural Finance, Financial Economics,

Computer-aided design and distributed system technology development for large space structures

Proposed large space structures have many characteristics that make them difficult to analyze and control. They are highly flexible, with components mathematically modeled by partial differential equations or very large systems of ordinary differential equations. They have many resonant frequencies, typically low and closely spaced. Natural damping may be low and/or improperly modeled. Coupled with stringent operational requirements of orientation, shape control, and vibration suppression, and the inability to perform adequate ground testing, these characteristics present an unconventional identification and control design problem to the systems theorist. Some of the research underway within Langley's Spacecraft Control Branch, Guidance and Control Division aimed at developing theory and algorithms to treat large space structures systems identification and control problems is described. The research areas to be considered are computer-aided design algorithms, and systems identification and control of distributed systems

Global and Partial Phase Synchronizations in Arrays of Piecewise Linear Time-Delay Systems

In this paper, we report the identification of global and partial phase synchronizations in linear arrays of unidirectionally coupled piecewise linear time-delay systems with two different coupling configurations. In particular, in a linear array with open end boundary conditions, global phase synchronization (GPS) is achieved by a sequential synchronization as a function of the coupling strength (a second order transition). Further, the asynchronous ones in the array with respect to the main sequentially synchronized cluster organize themselves to form clusters before they achieve synchronization with the main cluster. On the other hand, in a linear array with closed end boundary conditions (ring topology), partial phase synchronization (PPS) is achieved by forming different groups of phase synchronized clusters above some threshold value of the coupling strength (a first order transition) where they continue to be in a stable PPS state. We confirm the occurrence of both global and partial phase synchronizations in two different piecewise linear time-delay systems using various numerical methods.Comment: 26 pages, 25 figures, To Appear in International Journal of Bifurcation and Chaos, Vol. 22, No. 7 pp. 1250178 (1-25). arXiv admin note: substantial text overlap with arXiv:1007.280

Understanding Learning Style Variations among Undergraduate Students

A study was conducted in Vellore district of Tamil Nadu state to understand the learning styles of students. The term learning style refers to the way or method or approach by which a student learns. The study explored the possible learning style variations among agricultural, horticultural, engineering and arts & science students and their association with academic achievement. One hundred and twelve students were randomly selected from the four streams and their learning styles were analyzed. In the agricultural and horticultural streams, a majority of the students were auditory learners. They were also found to be predominantly unimodal learners. Overall, it was found that majority of the students were visual learners followed by auditory and kinesthetic style. The highest percentage of kinesthetic learners was found among engineering students. Trimodal learners scored the highest mean percentage of marks. The influence of learning styles on the academic achievements of the students did not show a significant relationship

Do Alternative Therapies Have a Role in Autism?

Interventions considered to be branches of Complementary & Alternative Medicine (CAM) for autism are on the rise. Many new treatments have emerged & traditional beliefs of Ayurveda, Yoga, Behavioral therapy, Speech therapy and Homoeopathy have gained popularity and advocacy among parents. It is imperative that data supporting new treatments should be scrutinized for scientific study design, clinical safety, and scientific validity, before embarking on them as modes of therapy. Practitioners take care in explaining the rationale behind the various approaches that they practice, it is important to indicate possible limitations too during the initial clinical examination and interactive session. Clinicians must remember that parents may have different beliefs regarding the effectiveness of treatment since their information is derived more from the ‘hear-say’ route when they compare benefits/effects of CAM therapies on other children and often underestimate differential tolerance for treatment risks. It is thus significant that practitioners do not assume a "don't ask, don't tell" posture. The scientific validation and support for many interventions is incomplete and very different from the recommendations of the American Academy of Pediatrics Policy Statement. In this article, we discuss the various modes of CAM and their utilities and limitations in relation to autism