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Search Results: 1 - 10 of 1630 matches for " AKBAR GHASEMI "
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Vegetative characteristics of Avicennia marina on the artificial inlet
Biodiversitas , 2012,
Abstract: The purpose of this project is attempt to ecological development of Avicennia marina in hyper saline condition. During 2001 and 2002 a restoration mangrove project " planting A. marina in artificial inlet in Bushehr Province, Iran" was carried out in Agriculture &Natural resources research center of Bushehr province in Sabkha lands. Some the vegetative characteristics of such as height, diameter and crown diameter in two aspects were recorded in 2012. To investigate physico-chemical properties of soil were taken in inside and outside of inlet and were analyzed: salinity, soil acidity, potassium, phosphorus, nitrogen, texture of soil were measured. Both of treatments were analyzed by T test in SAS Software. The result showed that a different significant between inside and outside of Inlet in soil acidity, electrical conductivity, potassium content and sand and clay percent. But were not different significant in N and P. After ten years halophyte plants such as: Salicornia herbacea and Halocnemum strobilaceum and animals such as: mudskippers were observed into this area. Site conditions have an influence on the growth of seedling, which shows a different growth in the outside and inside of artificial inlets.
Interference Alignment for the $K$ User MIMO Interference Channel
Akbar Ghasemi,Abolfazl Seyed Motahari,Amir Keyvan Khandani
Mathematics , 2009,
Abstract: We consider the $K$-user Multiple Input Multiple Output (MIMO) Gaussian interference channel with $M$ antennas at each transmitter and $N$ antennas at each receiver. It is assumed that channel coefficients are constant and are available at all transmitters and at all receivers. The main objective of this paper is to characterize the Degrees of Freedom (DoF) for this channel. Using a new interference alignment technique which has been recently introduced in \cite{abolfazl-final}, we show that $\frac{MN}{M+N} K$ degrees of freedom can be achieved for almost all channel realizations. Also, a new upper-bound on the DoF of this channel is provided. This upper-bound coincides with our achievable DoF for $K\geq K_u\define\frac{M+N}{\gcd(M,N)}$, where $\gcd(M,N)$ denotes the greatest common divisor of $M$ and $N$. This gives an exact characterization of DoF for $M\times N$ MIMO Gaussian interference channel in the case of $K\geq K_u$.
Interference Alignment for the MIMO Interference Channel with Delayed Local CSIT
Akbar Ghasemi,Abolfazl Seyed Motahari,Amir Keyvan Khandani
Mathematics , 2011,
Abstract: We consider the MIMO (multiple-input multiple-output) Gaussian interference channel with i.i.d. fading across antennas and channel uses and with the delayed local channel state information at the transmitters (CSIT). For the two-user case, achievability results for the degrees of freedom (DoF) region of this channel are provided. We also prove the tightness of our achievable DoF region for some antenna configurations. Interestingly, there are some cases in which the DoF region with delayed local CSIT is identical to the DoF region with perfect CSIT and that is strictly larger than the DoF region with no CSIT. We then consider the $K$-user MISO (multiple-input single-output) IC and show that the degrees of freedom of this channel could be greater than one with delayed local CSIT.
On the Degrees of Freedom of $K$-User SISO Interference and X Channels with Delayed CSIT
Mohammad Javad Abdoli,Akbar Ghasemi,Amir Keyvan Khandani
Mathematics , 2011, DOI: 10.1109/TIT.2013.2268154
Abstract: The $K$-user single-input single-output (SISO) AWGN interference channel and $2\times K$ SISO AWGN X channel are considered where the transmitters have the delayed channel state information (CSI) through noiseless feedback links. Multi-phase transmission schemes are proposed for both channels which possess novel ingredients, namely, multi-phase partial interference nulling, distributed interference management via user scheduling, and distributed higher-order symbol generation. The achieved degrees of freedom (DoF) values are greater than the best previously known DoFs for both channels with delayed CSI at transmitters.
Interference and X Networks with Noisy Cooperation and Feedback
Mohammad Javad Abdoli,Akbar Ghasemi,Amir Keyvan Khandani
Mathematics , 2012,
Abstract: The Gaussian $K$-user interference and $M\times K$ X channels are investigated with no instantaneous channel state information (CSI) at transmitters. First, it is assumed that the CSI is fed back to all nodes after a finite delay (delayed CSIT), and furthermore, the transmitters operate in full-duplex mode, i.e., they can transmit and receive simultaneously. Achievable results are obtained on the degrees of freedom (DoF) of these channels under the above assumption. It is observed that, in contrast with no CSIT and full CSIT models, when CSIT is delayed, the achievable DoFs for both channels with full-duplex transmitter cooperation are greater than the best available achievable results on their DoF without transmitter cooperation. Our results are the first to show that the full-duplex transmitter cooperation can potentially improve the channel DoF with delayed CSIT. Then, $K$-user interference and $K\times K$ X channels are considered with output feedback, wherein the channel output of each receiver is causally fed back to its corresponding transmitter. Our achievable results with output feedback demonstrate strict DoF improvements over those with the full-duplex delayed CSIT when $K>5$ in the $K$-user interference channel and $K>2$ in the $K\times K$ X channel. Next, the combination of delayed CSIT and output feedback, known as Shannon feedback, is studied and strictly higher DoFs compared to the output feedback model are achieved in the $K$-user interference channel when K=5 or $K>6$, and in the $K\times K$ X channel when $K>2$. Although being strictly greater than 1 and increasing with size of the networks, the achievable DoFs in all the models studied in this paper approach limiting values not greater than 2.
Study of Tsunamis by Dimensional Analysis  [PDF]
S. Ghasemi
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.39111
Abstract: Tsunamis are among the most terrifying natural hazards known to man and have been responsible for tre-mendous loss of life and property throughout history. In this paper by means of dimensional analysis, important non-dimensional groups in Tsunamis was studied and an equation to calculate the power of tsunamis was obtained. Also by this method and using tsunami basic physics, the height of waves near the coastline was estimated and results were compared by reported values.
Application of Linear Model Predictive Control and Input-Output Linearization to Constrained Control of 3D Cable Robots  [PDF]
Ali Ghasemi
Modern Mechanical Engineering (MME) , 2011, DOI: 10.4236/mme.2011.12009
Abstract: Cable robots are structurally the same as parallel robots but with the basic difference that cables can only pull the platform and cannot push it. This feature makes control of cable robots a lot more challenging compared to parallel robots. This paper introduces a controller for cable robots under force constraint. The controller is based on input-output linearization and linear model predictive control. Performance of input-output linearizing (IOL) controllers suffers due to constraints on input and output variables. This problem is successfully tackled by augmenting IOL controllers with linear model predictive controller (LMPC). The effecttiveness of the proposed method is illustrated by numerical simulation.
Postmodern Science Edification Philosophy  [PDF]
Akbar Nikkhah
Open Journal of Philosophy (OJPP) , 2011, DOI: 10.4236/ojpp.2011.11007
Abstract: The objective is to introduce and describe a new philosophy for global science edification that will determine the extent and nature of humans’ accomplishments. These will affect life quality worldwide. Science as an ultimate essence encircles theoretical and applied findings and discoveries. These can only contribute to forming a trivial core, whilst the most crucial are insightful moral surroundings. Morality is most concerned with mentorship commitments. To sustain a dense and rigid shape that progressively improves science and life quality, imagination must be complemented with harmonizing approaches. Such perceptions become an obligation as growing knowledge creates novel questions and challenges. The upper tree of science glorified with blooming branches of knowledge, particularly over the last few centuries, is predicted to undergo progressive declines in the strength of its edification foundations unless the lower tree receives most-deserving mentorship contemplations. The upper tree describes tangible science products in routin life, and the lower tree represents sustainable mentorship. Mentors must replace teachers, by definition, and commit to generating more qualified educators than themselves. Mentors are expected to welcome and manage challenges from mentees. Challenges play crucial roles in granting mentees with integrated pathways of scientific development. The resulting pictures will be eagerly prone to revisions and elaborations as mentees themselves step into the pathway. This systematic edification will strengthen science roots in mentees’ minds and will uphold a sturdy science body for society. Science pictured as an integrated circle grants a prospect to envision where humans are and where not to end up. Maintaining a definitive shape for science in any major before and while enriching central cores with experimental novelties in minds and laboratories is crucial to improving man’s fulfillment of time in the third millennium. Such integrities are an obligation to optimally preserve and utilize what humans have achieved thus far and continue to accomplish.
Science of Camel and Yak Milks: Human Nutrition and Health Perspectives  [PDF]
Akbar Nikkhah
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.26092
Abstract: Camels and yaks milks are rich in numerous bioactive substances that function beyond their nutritive value. Milk Camel milk is more similar to goat milk and contains less short-chain fatty acids than cow, sheep and buffalo milks, and about 3 times greater vitamin-C than cow milk. One kg of camel milk meets 100% of daily human requirements for calcium and phosphorus, 57.6% for potassium, 40% for iron, copper, zinc and magnesium, and 24% for sodium. Camel milk helps treat liver problems, lowers bilirubin output, lightens vitamin inadequacy and nutrient deficiency, and boosts immunity. Camel milk reduces allergies caused by cow dairy products. Camel milk has low milk fat made mainly from polyunsaturated fatty acids. It lacks ß-lactoglobulin and is rich in immunoglobulins, compatible with human milk. Yak milk has 16.9 - 17.7% solids, 4.9 - 5.3% protein, 5.5 - 7.2% fat, 4.5 - 5.0% lactose, and 0.8 - 0.9% minerals. Yak milk fat is richer in polyunsaturated fatty acids, protein, casein and fat than cow milk. Yak milk casein is used to produce antihypertensive peptides with capacities for producing value-added functional foods and proteins. Continual system-atic education of milk science especially for non-cow species will be an obligation for health implications to be optimally perceived by human populations worldwide.
Bioscience of ruminant intake evolution: feeding time models  [PDF]
Akbar Nikkhah
Advances in Bioscience and Biotechnology (ABB) , 2011, DOI: 10.4236/abb.2011.24039
Abstract: Ruminants have evolved to ruminate mostly over- night and graze during day. As such, rumen fermentation, post-rumen nutrient assimilation and peripheral metabolism have 24-h patterns. These evolutionary rhythms in eating behavior and metabolism have led to annual, seasonal, and circadian rhythms in ruminant endocrinology. Such natural patterns have encountered dramatic shifts in productivity in the last few decades. For optimum nutrient use and animal health, securing a synchrony between external cues and ruminant internal conditions is essential. Most recent discoveriess suggest alterations in post-prandial intake patterns of non-grazing lactating cows by altered feeding time. Eating rate and feed intake within the first 3 h after feeding have been increased by evening instead of morning feeding. As a result, postprandial patterns in rumen fermentation and peripheral blood levels of metabolites and hormones have been altered. These findings and insights establish a chronological nature for intake regulation in modern ruminants. Feeding time is a major external cue that affects eating extent, rate and efficiency in ruminants. Time of feeding requires special consideration and more mechanistic evaluations for animals and humans.
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