Performance of a Wireless Sensor Network MAC Protocol with a Global Sleep Schedule

Somnath Ghosh,Prakash Veeraraghavan,Samar Singh,Lei Zhang 보안공학연구지원센터 2009 International Journal of Multimedia and Ubiquitous Vol.4 No.2

Medium access control protocols for wireless sensor networks are almost always designed to be energy efficient. One mechanism used to reduce energy expenditure is to periodically turn off the radio receivers of the sensor nodes in a coordinated manner. The nodes with radio receivers turned off are said to be in the sleep mode. Nodes form virtual clusters based on common sleep schedules. However, protocols like the widely used S-MAC may require some nodes to follow multiple sleep schedules causing them to wake up more often than the other nodes. This paper demonstrates in some wireless sensor networks using S-MAC, a significant proportion of the nodes may have to stay awake much longer than envisaged. A modification of the protocol is then proposed to eliminate the need for some nodes to stay awake longer than the other nodes. The modified version improves the energy efficiency and increases the life span of a wireless sensor network. The paper concludes with the result of simulation studies which indicate that the use of the proposed protocol is expected to increase the life time of wireless sensor networks significantly.

Improving Energy Efficiency in FPGA Through Judicious Mapping of Computation to Embedded Memory Blocks

Ghosh, Anandaroop,Paul, Somnath,Park, Jongsun,Bhunia, Swarup IEEE 2014 IEEE transactions on very large scale integration Vol.22 No.6

<P>Field-programmable gate arrays (FPGAs) are being increasingly used as a preferred prototyping and accelerator platform for diverse application domains, such as digital signal processing (DSP), security, and real-time multimedia processing. However, mapping of these applications to FPGA typically suffers from poor energy efficiency because of high energy overhead of programmable interconnects (PI) in FPGA devices. This paper presents an energy-efficient heterogenous application mapping framework in FPGA, where the conventional application mappings to logic and DSP blocks (for DSP-enhanced FPGA devices) are combined with judicious mapping of specific computations to embedded memory blocks. A complete mapping methodology including functional decomposition, fusion, and optimal packing of operations is proposed and efficiently used to reduce the large energy overhead of PIs. Effectiveness of the proposed methodology is verified for a set of common applications using a commercial FPGA system. Experimental results show that the proposed heterogenous mapping approach achieves significant energy improvement for different input bit-widths (e.g., more than 35% of energy savings with 8 bit or smaller bit inputs compared to the corresponding mapping in configurable logic blocks). For further reduction of energy, we propose an energy/accuracy tradeoff approach, where the input operand bit-width is dynamically truncated to reduce memory area and energy at the expense of modest degradation in output-accuracy. We show that using a preferential truncation method, up to 88.6% energy savings can be achieved in a 32-tap finite impulse response filter with modest impact on the filter performance.</P>

Hyperhomocysteinemia, a Biochemical Tool for Differentiating Ischemic and Nonischemic Central Retinal Vein Occlusion during the Early Acute Phase

Kapil Deb Lahiri,Somnath Mukherjee,Sambuddha Ghosh,Suman Mukherjee,Jayanta Dutta,Himadri Datta,Harendra Nath Das 대한안과학회 2015 Korean Journal of Ophthalmology Vol.29 No.2

Purpose: The purpose of the study was to differentiate ischemic central retinal vein occlusion (CRVO) from nonischemic CRVO during the early acute phase using plasma homocysteine as a biochemical marker. Methods: Fasting plasma homocysteine, serum vitamin B12, and folate levels were measured in 108 consecutive unilateral elderly adult (age >50 years) ischemic CRVO patients in the absence of local and systemic disease and compared with a total of 144 age and sex matched nonischemic CRVO patients and 120 age and sex matched healthy control subjects. Results: Homocysteine level was significantly increased in the patients with ischemic CRVO in comparison with nonischemic CRVO patients (p = 0.009) and also in comparison with control subjects (p < 0.001). Analysis also showed that hyperhomocysteinemia was associated with increased incidence of ischemic CRVO (odds ratio, 18) than that for nonischemic CRVO (odds ratio, 4.5). Serum vitamin B12 and folate levels were significantly lower (p < 0.001) in CRVO patients compared to the control but were not significantly different between nonischemic and ischemic CRVO patients (p > 0.1). Conclusions: Hyperhomocysteinemia can be regarded as useful in differentiating nonischemic and ischemic CRVO during the early acute phase in absence of local and systemic disease in the elderly adult (age >50 years) population.

Homogenization based continuum damage mechanics model for monotonic and cyclic damage evolution in 3D composites

Jain, Jayesh R.,Ghosh, Somnath Techno-Press 2008 Interaction and multiscale mechanics Vol.1 No.2

This paper develops a 3D homogenization based continuum damage mechanics (HCDM) model for fiber reinforced composites undergoing micromechanical damage under monotonic and cyclic loading. Micromechanical damage in a representative volume element (RVE) of the material occurs by fiber-matrix interfacial debonding, which is incorporated in the model through a hysteretic bilinear cohesive zone model. The proposed model expresses a damage evolution surface in the strain space in the principal damage coordinate system or PDCS. PDCS enables the model to account for the effect of non-proportional load history. The loading/unloading criterion during cyclic loading is based on the scalar product of the strain increment and the normal to the damage surface in strain space. The material constitutive law involves a fourth order orthotropic tensor with stiffness characterized as a macroscopic internal variable. Three dimensional damage in composites is accounted for through functional forms of the fourth order damage tensor in terms of components of macroscopic strain and elastic stiffness tensors. The HCDM model parameters are calibrated from homogenization of micromechanical solutions of the RVE for a few representative strain histories. The proposed model is validated by comparing results of the HCDM model with pure micromechanical analysis results followed by homogenization. Finally, the potential of HCDM model as a design tool is demonstrated through macro-micro analysis of monotonic and cyclic damage progression in composite structures.

Folk to functional: An explorative overview of rice-based fermented foods and beverages in India

Mousumi Ray,Kuntal Ghosh,Somnath Singh,Keshab Chandra Mondal 한국식품연구원 2016 Journal of Ethnic Foods Vol.3 No.1

Fermented foods share an integral part of age-old wisdom from ancient Indian civilization. Over the generations, this pioneering practice of food fermentation has expanded and improved to preserve and fortify the available food resources, particularly to meet the hidden hunger. India, being the second largest producer of rice, has a great history of traditional rice-based fermented foods with different tastes and textures linked with cultural diversity and mostly prepared by rural women following village art techniques. Some of them have been scientifically investigated and it has been revealed that microflora in natural or starter culture plays imperative roles to bio-embolden the rice with varieties of health promoting macronutrients and micronutrients, phytochemicals, and other functional components during fermentation. In this review, some explorative information on traditional rice-based foods and beverages has been assembled to illustrate the global interest in Indian food heritage and their functional aspects. The review also deals with the preparation of raw materials, traditional processing, composition, and ethno-medicinal importance of each food to encourage entrepreneurs to develop large-scale production to meet the growing market demand of functional foods.

A Comparative Study of Physical Fitness Index (PFI) and Predicted Maximum Aerobic Capacity (VO2max) among the Different Groups of Female Students in West Bengal, India

( Banibrata Das ),( Tirthankar Ghosh ),( Somnath Gangopadhyay ) 체육과학연구원 2010 International Journal of Applied Sports Sciences Vol.22 No.1

Physical Fitness Index (PFI) is considered an important and valuable parameter in the field of sports and exercise science. The main aim of this study is to assess and compare the physical fitness and cardio respiratory fitness in terms of maximum aerobic capacity (VO2max) among the urban female students and rural female students of West Bengal. Forty sedentary young female students from each of the urban as well as rural sectors of West Bengal were recruited by simple random sampling. PFI was determined by Harvard step test and VO2max was determined by the indirect Queen`s college step test (QCT) (QCT is the simplest one to determine cardio respiratory fitness in terms of maximum oxygen uptake) method for each group of subjects. From this study it can be concluded that the rural female students do not have a statistical higher significant value of PFI and VO2max score than the urban female students. No significant correlation was found between age and PFI in both groups (urban & rural) of students. PFI was found to have significant negative correlation with body weight, BSA, BMI with urban female students and body height, weight and BSA with the rural female students. PFI score of urban and rural female students is positively and highly correlated with VO2max (QCT).

Double-Layer Antireflection Coating of MgF2 SiNx for Crystalline Silicon Solar Cells

Suresh Kumar Dhungel,이준신,JINSU Yoo,김경해,SOMNATH GHOSH,정성욱 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.3

Single layer antireflection coatings are not able to cover a broad range of the solar spectrum. This research investigated changes in the performance parameters of crystalline silicon solar cells caused by a thin film of magnesium fluoride (MgF2) deposited on top of a silicon nitride (SiNx) film already deposited on the emitter layer of a solar cell. The MgF2 film depositions on crystalline cells of large area (125 mm × 125 mm) were carried out by using thermal evaporation under high vacuum ( 10−6 Torr) with a special mask to protect the front metal contact on the busbars after cell fabrication. Significant improvements in the conversion eciency (E) and the short-circuit current (Isc) of the cells were obtained after deposition of the MgF2 layer. Comparison of the unscaled quantum eciencies (QE) before and after MgF2 deposition showed a significant improvement in spectral response, especially in the wavelength range above 700 nm. The theoretical reflectance of the surface with a double-layer antireflection (DLAR) coating, as obtained by simulation, was found to be in agreement with the experimentally measured surface reflectance pattern. Single and multicrystalline silicon solar cells with respective conversion eciencies of 17 and 16 % were fabricated with a conventional solar cell fabrication line.