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Search Results: 1 - 10 of 1039 matches for " Vishnu Baba Sundaresan "
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Self-Healing of Ionomeric Polymers with Carbon Fibers from Medium-Velocity Impact and Resistive Heating
Vishnu Baba Sundaresan,Andrew Morgan,Matt Castellucci
Smart Materials Research , 2013, DOI: 10.1155/2013/271546
Abstract: Self-healing materials science has seen significant advances in the last decade. Recent efforts have demonstrated healing in polymeric materials through chemical reaction, thermal treatment, and ultraviolet irradiation. The existing technology for healing polymeric materials through the aforementioned mechanisms produces an irreversible change in the material and makes it unsuitable for subsequent healing cycles. To overcome these disadvantages, we demonstrate a new composite self-healing material made from an ionomer (Surlyn) and carbon fiber that can sustain damage from medium-velocity impact and heal from the energy of the impact. Furthermore, the carbon fiber embedded in the polymer matrix results in resistive heating of the polymer matrix locally, melts the ionomer matrix around the damage, and heals the material at the damaged location. This paper presents methods to melt-process Surlyn with carbon fiber and demonstrates healing in the material through medium-velocity impact tests, resistive heating, and imaging through electron and optical microscopy. A new metric for quantifying self-healing in the sample, called width-heal ratio, is developed, and we report that the Surlyn-carbon fiber-based material under an optimal rate of heating and at the correct temperature has a width-heal ratio of >0.9, thereby demonstrating complete recovery from the damage. 1. Introduction Damage detection and self-healing are unique properties of biological materials and systems. In such systems, a damage event triggers internal processes that generate the healing response and extend the life of the material. This unique property of biological materials has served as the inspiration for self-healing materials in engineering. In the most common self-healing concepts developed to date, damage events are directly or electronically coupled to the release of the healing agents to heal the damage in the material. The most commonly used healing agents such as chemical binders, heat, and light alter the chemical composition and microstructure of the material to heal the damage and restore strength at the damage site. The capsule-based method developed by White and coworkers [1–4] uses a chemical binder that is released into the matrix of the composite material in the event of a damage. The binder combines with the matrix or hardening agent present in adjacent microcapsule to heal the damage. A variation of the microcapsule-based technique uses vascular networks filled with healing agents to heal structural damage [5–12]. In another variation of this method, hollow glass
The MX/M/1 Queue with Multiple Working Vacation  [PDF]
Yutaka Baba
American Journal of Operations Research (AJOR) , 2012, DOI: 10.4236/ajor.2012.22025
Abstract: We study a batch arrival MX/M/1 queue with multiple working vacation. The server serves customers at a lower rate rather than completely stopping service during the service period. Using a quasi upper triangular transition probability matrix of two-dimensional Markov chain and matrix analytic method, the probability generating function (PGF) of the stationary system length distribution is obtained, from which we obtain the stochastic decomposition structure of system length which indicates the relationship with that of the MX/M/1 queue without vacation. Some performance indices are derived by using the PGF of the stationary system length distribution. It is important that we obtain the Laplace Stieltjes transform (LST) of the stationary waiting time distribution. Further, we obtain the mean system length and the mean waiting time. Finally, numerical results for some special cases are presented to show the effects of system parameters.
Sundaresan K
Indian Journal of Ophthalmology , 1967,
Guessing under source uncertainty
Rajesh Sundaresan
Mathematics , 2006, DOI: 10.1109/TIT.2006.887466
Abstract: This paper considers the problem of guessing the realization of a finite alphabet source when some side information is provided. The only knowledge the guesser has about the source and the correlated side information is that the joint source is one among a family. A notion of redundancy is first defined and a new divergence quantity that measures this redundancy is identified. This divergence quantity shares the Pythagorean property with the Kullback-Leibler divergence. Good guessing strategies that minimize the supremum redundancy (over the family) are then identified. The min-sup value measures the richness of the uncertainty set. The min-sup redundancies for two examples - the families of discrete memoryless sources and finite-state arbitrarily varying sources - are then determined.
Guessing based on length functions
Rajesh Sundaresan
Mathematics , 2007,
Abstract: A guessing wiretapper's performance on a Shannon cipher system is analyzed for a source with memory. Close relationships between guessing functions and length functions are first established. Subsequently, asymptotically optimal encryption and attack strategies are identified and their performances analyzed for sources with memory. The performance metrics are exponents of guessing moments and probability of large deviations. The metrics are then characterized for unifilar sources. Universal asymptotically optimal encryption and attack strategies are also identified for unifilar sources. Guessing in the increasing order of Lempel-Ziv coding lengths is proposed for finite-state sources, and shown to be asymptotically optimal. Finally, competitive optimality properties of guessing in the increasing order of description lengths and Lempel-Ziv coding lengths are demonstrated.
Assessing gestational age of babies: Performance of obstetric ultrasound scan compared to that from the combination of Naegle’s rule and Dubowitz score in the 21st century  [PDF]
Baba Usman Ahmadu
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.58A2005

Background: Some researchers have suggested that when Naegle’s rule (NR) and Dubowitz score (DS) are combined, it could out-perform obstetric ultrasound scan (USS). Others still believe that obstetric USS alone is still effective relative to the combination of NR rule and DS in assessing the gestational age (GA) of babies. Objectives: To determine and compare the GA of babies using obstetric USS, NR and DS; and to provide relevant public health information on obstetric USS in the 21st century. Methods: Subjects were selected using systematic random sampling and the GA of babies was determined using obstetric USS, NR, and DS. Statistical package for social science (SPSS) statistical software version 16, Illinois, Chicago USA was used for all data analysis. Results: Eightyfive mother-baby pairs were studied. Forty-four babies (52%) were males and 41 (48%) females. Sixty four (75%) were term with a mean (SD) BW of 3.02 (0.59) at 95%CI (2.89 - 3.14) kg. The overall mean GA of the babies was 38.49 (2.89) at 95%CI (38.14 - 38.85) weeks. The mean GA using obstetric USS, NR and DS were 38.52 (1.98) at 95%CI (38.14 - 38.99), 38.09 (4.13) at 95%CI (37.20- 38.99) and 38.82 (2.02) at 95%CI (38.39 - 39.26), but comparison of these means was not significant (p = 0.256). Combined mean GA by NR and DS was 38.46 (3.26) at 95%CI (37.96 - 38.95). Comparing this mean with mean GA obtained by obstetric USS was also not significant (p = 0.885). Conclusion: The GA assessments by Obstetric USS, NR and DS were all reliable, and Obstetric USS performed effectively relative to combined NR and DS.

Looking at maternal inequalities (socioeconomic class, age and human immunodeficiency virus status) to predict well-being of neonates during infancy  [PDF]
Baba Usman Ahmadu
Health (Health) , 2013, DOI: 10.4236/health.2013.58A4001

Background: Infant health inequalities responsible for high infant sicknesses and deaths in our setting could depend to a large extend on maternal inequalities like socioeconomic class (SEC), age and human immunodeficiency virus (HIV). Objective: To look at maternal inequalities (SEC, Age and HIV), to predict well-being of neonates during infancy. Methods: Subjects were selected using systematic random sampling. Maternal education, occupation, age and HIV status were obtained using a questionnaire; their SEC was derived using the Oyedeji’s model. Gestational age (GA) of the neonates was estimated from their mother’s last menstrual period, obstetric ultrasound scan reports or the Dubowitz criteria; and birthweight (BW) was determined using the basinet weighing scale, which has a sensitivity of 50 grams. Results: Ninety mother-neonatal pairs were enrolled, 47 (52.2%) neonates were males and 43 (47.8%) females. Most of the neonates were term 66 (73.3%) and of normal BW 75 (83.4%). A significant association existed between maternal variables and the likely hood of the subjects being less healthy during infancy (χ2 = 126.528, p < 0.005). Maternal age had a negative correlation coefficient with GA (r = -0.200) and BW (r = -0.115) and comparison of MA, GA and BW was significant (F = 2662.92, p < 0.0001). Conclusion: The combine effects of maternal SEC, Age and HIV have predicted less healthy neonates during infancy. Neonates in the present work are more prone to sicknesses and ill-health during infancy.

Diversity Management for Improving Performance in Mobile Telephone Network (MTN) Ghana Limited  [PDF]
Alhaji Yussif Baba Suleman
American Journal of Industrial and Business Management (AJIBM) , 2017, DOI: 10.4236/ajibm.2017.710083
Abstract: The study examined the impact of diversity management on the general performance of organizations in the telecommunication industry in Ghana, through a case study on Mobile Telephone Network (MTN) Ghana limited. The target population was made up of top and middle management teams of MTN Ghana ltd, and the purposive sampling technique was used to select a sample of ten (10) respondents for the study. Questionnaires were the instruments used for data collection and the data collected were analysed using tables. The key findings were that, diversity management has a positive influence on the performance of MTN Ghana ltd; and though diversity management is present in the company, management of it is improperly undertaken. It is therefore recommended that, top management team should give their support to diversity management and establish a complete strategy for diversity management in the company. Education and training programs may be organized for employees to learn about diversity and how to handle its complex issues in order to enhance performance in the organization.
Golden Research Thoughts , 2012, DOI: 10.9780/22315063
Abstract: Mulk Raj Anand was born in 1905 in Peshawar in present-day Pakistan. Apioneer of Indian writing in English, he gained an international following early in his life. His novels Coolie and Untouchable set an entire generation of educated Indians thinking about India's social evils that were perpetuated in the name of religion and tradition. These and other early novels and short stories brought into sharp focus the dehumanizing contradictions within colonized Indian society. Through his writings he revealed that in addition to the foreign colonialism of Britain there existed layers of colonialism within Indian society.
A result of commutativity of rings
Vishnu Gupta
International Journal of Mathematics and Mathematical Sciences , 1994, DOI: 10.1155/s0161171294000104
Abstract: In this paper we prove the following:
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