Sumit Singh - Academia.edu (original) (raw)

Papers by Sumit Singh

Tropical Agriculture, Apr 1, 2002

The effect of etiolation on phenol content and polyphenol oxidase (PPO) activity at the precultur... more The effect of etiolation on phenol content and polyphenol oxidase (PPO) activity at the preculture stage and on post-culture phenolic exudation and explant survival was studied in shoot tips of eight mango (Mangifera indica L.) cultivars, viz., Amrapali, Mallika, Langra, Bhadauran, Tommy Atkins, Eldon, Sensation, and Alphonso. Etiolation treatment resulted in marked decline in PPO activity and phenol content at the pre-culture stage and phenolic exudation at the postculture stage, which in turn increased the explant survival in Murashige and Skoog's culture medium. Etiolated shoots had low PPO activity (0.496 ?A400 g-1 min-1) and phenol content (11.19 mg g-1 fresh tissue wt) at the pre-culture stage, exuded a smaller amount of phenols into the culture medium, and had higher explant survival (36.1%) compared to non-etiolated shoots, which had higher PPO activity (1.081 ?A400 g-1 min-1) and phenolic content (18.27 mg g-1 fresh tissue wt), exuded a greater amount of phenols into the medium (0.250 mg mLmedium), and had low survival of explants (7.7%). Among the cultivars, Bhadauran exhibited the highest PPO activity (1.468 ?A400 g-1 min-1) and phenol content (27.74 mg g-1 fresh tissue wt), exuded the greatest amount of phenols into the culture medium (0.340 mg mL-1 of medium), and had the minimum explant survival (3.4%) in contrast to Tommy Atkins, which exhibited the lowest PPO activity (0.582 ?A400 g-1 min-1) and phenol content (8.17 mg g-1 fresh tissue wt), exuded the smallest amount of phenols into the medium (0.095 mg mL-1 of medium), and had the highest explant survival (38.6%). Explant survival, in general, was very high (59.0%) initially (3rd day after culture initiation) but declined drastically thereafter to 0.9% after the 21st day of culture. The interactions between etiolation x cultivar, etiolation x time, cultivar x time, and etiolation x cultivar x time, were significant for explant survival. A strong positive correlation existed between PPO activity and phenol exudation (r = 0.912) and phenol content and exudation (r = 0.892), whereas the correlations between PPO activity and explant survival (r = -0.872) and phenol content and explant survival (r = -0.899) were strongly negative.

Energy, Nov 1, 2017

This work aims at proposing a sliding mode observer (SMO) based nonlinear multivariable sliding m... more This work aims at proposing a sliding mode observer (SMO) based nonlinear multivariable sliding mode controller (SMC) and globally linearizing controller (GLC) for a proton exchange membrane fuel cell (PEMFC). First, a nonlinear dynamic model of a methanol reformer is developed to produce hydrogen for the PEMFC. The reformer model has been verified and then its parameter values are modified to scale-up the reformer for fitting with a real time fuel cell. Subsequently, a nonlinear PEMFC model is formulated and validated with experimental data. The SMC consists of a controller and an estimator, whereas the GLC consists of a transformer, an estimator and a dual-loop external proportional integral (PI) controller. A transformer that relates the manipulated variable with the external control output is developed using the differential geometry. For both the control schemes, a nonlinear sliding mode observer is formulated to avoid any additional requirement of sensor to measure other than the controlled variables. Chattering occurred in the SMO and SMC due to very large frequency stroke of the sign function to minimize the estimation error has been eliminated by using a saturation function. Finally, the proposed SMO based SMC and GLC structure are tested for the integrated methanol reformer-PEMFC system. Observing an excellent estimation performance of the SMO, we investigate a comparative performance between the SMC and GLC with reference to a dual-loop PI controller.

IEEE Journal of Solid-State Circuits

This article presents a single-stage single-ended (SE) and a multistage pseudo-differential casco... more This article presents a single-stage single-ended (SE) and a multistage pseudo-differential cascode low-noise amplifiers (D-LNA) with their center frequencies at 235 and 290 GHz, respectively. Both low-noise amplifiers (LNAs) are designed beyond half of the maximum frequency of oscillation (f max) in 130-nm SiGe BiCMOS technology with f t / f max of 300/450 GHz. Implications of gain-boosting and noise reduction techniques in cascode structure are analyzed and it is observed that beyond f max /2, these techniques do not provide desired benefits. The single-stage SE LNA is designed to ascertain the theoretical analysis, and the same analysis is further implemented in staggered tuned four-stage LNA. Single-stage SE LNA provides a small signal gain of 7.8 dB at 235 GHz with 50 GHz of 3-dB bandwidth by consuming 18 mW of power. Four-stage differential LNA gives 12.9 dB of gain at center frequency 290 GHz and 11.2 dB at 300 GHz by drawing 68 mA current from the 2-V supply. The 3-dB bandwidth of differential LNA is measured to be 23 GHz. Noise figure measurements of both LNAs are performed using a gain-method technique with their measured noise figure values of 11 and 16 dB, respectively. This work successfully demonstrates the possibility of using a Si-based process to implement amplifiers beyond f max /2. To the authors' best knowledge, the four-stage differential LNA achieves, without any gain-boosting technique, the highest gain at 2/3(f max) with decent noise figure performance in SiGe technology. Index Terms-High current model (HICUM), low-noise amplifiers (LNAs), maximum frequency of oscillation (f max), receivers, SiGe BiCMOS integrated circuits, sub-THz and THz integrated circuits, vertical bipolar intercompany model (VBIC).

2019 IEEE Nordic Circuits and Systems Conference (NORCAS): NORCHIP and International Symposium of System-on-Chip (SoC)

This paper presents an alternative interpretation to Groszkowski's effect, which states that the ... more This paper presents an alternative interpretation to Groszkowski's effect, which states that the oscillation frequency of a harmonic oscillator is shifted due to the higher harmonic currents flowing into the LC tank. Groszkowki's analysis starts by taking a strictly memoryless amplifier, to which he derives and expression for balance of reactive powers. Then he interprets the frequency shift as a matter of balance of reactive energy in the tank. Here we show that although a conductive amplifier is memoryless, it can still show phase shift at the fundamental tone. This is due to mixing of the fundamental and harmonics in the nonlinear i-v response of the amplifier. Now the new interpretation comes from the oscillation condition: if the amplifier shows phase shift, the tank needs to compensate it, and this causes the shift in the oscillation frequency. The mechanism is explained, analysed symbolically, and verified numerically.

Current Journal of Applied Science and Technology, 2020

Aims: To study the effect of different micronutrients and number of foliar spray on fruit quality... more Aims: To study the effect of different micronutrients and number of foliar spray on fruit quality and leaf nutrient content of peach. Study Design: The experiment comprised of seven treatments and conducted on seven years old plants in Randomized Block Design with three replications. Place and Duration of Study: The experiment was conducted at the experimental orchard of Department of Horticulture, CCS Haryana Agricultural University, Hisar during the year 2018. Methodology: The treatments included in the study consisted of three micro-nutrients [T1- ZnSO4 @ 0.2%, T2- ZnSO4 @ 0.3%, T3- FeSO4 @ 0.2%, T4- FeSO4 @ 0.3%, T5- Boric acid @ 0.1%, T6- Boric acid @ 0.2%, T7- Control (water spray)] each applied as foliar spray at different concentration as single and double spray. Results: The results showed that foliar spray of micronutrients significantly improved quality and leaf nutrient status in peach cv. Shan-e-Punjab. The foliar spray of FeSO4 @ 0.2% (T3) found to be the best treatmen...

Bulletin of the Iranian Mathematical Society, 2019

In this paper, we introduced relatively star-C-Hurewicz property in topological spaces following ... more In this paper, we introduced relatively star-C-Hurewicz property in topological spaces following the approach of Bonanzinga and Pansera (

IOSR Journal of Engineering, 2014

As the competition in market is growing at a very fast pace, one can survive in today's industria... more As the competition in market is growing at a very fast pace, one can survive in today's industrial world by adopting the philosophy of Lean Manufacturing. In order to stay competitive, producing cheaper products at a faster rate Lean Manufacturing would help the industry. This paper represents a case study of Die casting industry. This case study is used to illustrate the steps in implementation of lean manufacturing providing actual and very positive results. The implementation plan is based on five major areas of wastes including Defects, Inventory, Excessive material movement, Delay due to waiting and Inappropriate processing in a die casting industry. The suggested implementation plan is being sub divided into three phases.

International Journal of Computer Applications, 2011

The importance of Ad-hoc network is due to its nature of infrastructure-less and decentralization... more The importance of Ad-hoc network is due to its nature of infrastructure-less and decentralization. In Ad-hoc network some nodes can become a critical spot in the network as they forward the packets to most of their neighbors. These critical nodes can deplete their battery power earlier, because of excessive load and processing for data forwarding. These unbalanced loads turn to nodes failure, network partition and reduce the route lifetime and route reliability. Energy consumption issue is a vital research topic in wireless ad hoc networks, because wireless nodes in such networks operate on limited battery power. This model paper describes An Energy and Traffic Aware Routing approach as an extension of AODV algorithm for Ad hoc network, utilizing the high energy path based on Route Selection Function. Our proposed algorithm adapts existing AODV routing protocol to improve performance in terms of traffic load on node, energy conservation and other performance metrics. The purpose of Route Selection Function is to improve lifespan of Ad hoc network and corresponding effect on overall network performance.

Volume 2B: Advanced Manufacturing, 2013

Rubber parts find a wide range of applications in several industrial sectors. Machining of rubber... more Rubber parts find a wide range of applications in several industrial sectors. Machining of rubber to produce final parts is preferred over using the conventional molding methods for the economic advantage of prior. Because of the complexity in the machining of rubber, not much experimental research has been documented in this area. The present work thus aims at machining of rubber using conventional lathe machine fit with a conventional grinding tool. Nitrile rubber rolls having a Shore hardness value of 30 is used for the experimental purpose. Speed, feed rate, and depth of cut are considered as the input machining parameters, and the surface roughness is selected as the response variable. Taguchi's orthogonal array method is used for optimizing. Analysis of variance (ANOVA) is used to determine the significance of each parameter, and the regression analysis is used to develop the linear analytical predicting model. The result obtained indicate N 2 f 1 D 1 as the optimum condition. The linear model developed shows a very high degree of fitness and a very high degree of accuracy in prediction with an error of less than 1% between the experimental and predicted values of the surface roughness.

International Journal of Computer Applications, 2011

An important and essential issue for mobile ad-hoc networks (MANETs) is routing protocol design i... more An important and essential issue for mobile ad-hoc networks (MANETs) is routing protocol design i.e. a major technical challenge due to the dynamism of the network. The work of this paper is inspired by the thought of taking account of several factors in wireless mobile ad-hoc networks (MANETs) routing design in a unified way. The rational of our inspiration is that most of the enhancements in DYMO protocol have been based on one criteria i.e. shortest path considered or multipath. There are several works in other On-demand routing protocols which considered some factors in a unified way. Therefore, we propose a routing mechanism i.e. "EA-DYMO Energy Aware Dynamic MANET On demand". In this routing mechanism, we would consider both the traffic load and energy aware path in a unified way. In this paper, we are modifying route selection procedure by taking the ratio of the energy factor as well as the average traffic load for each path, analysis and simulation we will consider as our future work.

FEMS Immunology & Medical Microbiology, 2002

Immune responses appropriate for control of an intracellular pathogen are generated in mice infec... more Immune responses appropriate for control of an intracellular pathogen are generated in mice infected with Brucella abortus, shown by the ability of T cells to adoptively transfer resistance to naive mice. The infection nevertheless persists for months. It was hypothesized that one factor in maintaining the infection despite the presence of immune T cells was suboptimal expression of major histocompatibility complex (MHC) molecules on macrophages containing brucellae. This would allow B. abortus to elude detection by the host's immune system. To test this, B. abortus organisms expressing green fluorescent protein (GFP-Brucella) were constructed and three-color flow cytometry used to evaluate MHC expression on macrophages following in vitro or in vivo infection. When infected in vitro, the levels of MHC class I and class II expression on J774 macrophages containing GFP-Brucella were the same or higher than on macrophages without GFP-Brucella in the same cultures. Similarly, the MHC expression was higher on GFP þ peritoneal exudate cells following infection or phagocytosis of heat-killed GFP-Brucella than it was on uninfected peritoneal exudate cells. Following in vivo infection of mice the level of MHC class I and II expression on GFP þ cells in their spleens (the main site of infection) also tended to be as high as or higher than that on the GFP-negative cells. The only in vivo GFP þ cells that showed a decreased MHC expression was a population of splenic Mac1 þ cells recovered from interferon-Q gene-disrupted mice at the time of their death due to an overwhelming number of bacteria per spleen. Overall, it was concluded that decreased MHC expression is not a general principle associated with brucella infection of macrophages and thus not likely to contribute to maintenance of the chronic infection.

IEEE INFOCOM 2009, 2009

We investigate an architecture for multi-Gigabit outdoor mesh networks operating in the unlicense... more We investigate an architecture for multi-Gigabit outdoor mesh networks operating in the unlicensed 60 GHz "millimeter (mm) wave" band. In this band, the use of narrow beams is essential for attaining the required link ranges in order to overcome the higher path loss at mm wave carrier frequencies. However, highly directional links make standard MAC methods for interference management, such as carrier sense multiple access, which rely on neighboring nodes hearing each other, become inapplicable. In this paper, we study the extent to which we can reduce, or even dispense with, interference management, by exploiting the reduction in interference due to the narrow beamwidths and the oxygen absorption characteristic of the 60 GHz band. We provide a probabilistic analysis of the interference incurred due to uncoordinated transmissions, and show that, for the parameters considered, the links in the network can be thought of as pseudo-wired. That is, interference can essentially be ignored in MAC design, and the challenge is to schedule half-duplex transmissions in the face of the "deafness" resulting from highly directional links. We provide preliminary simulation results to validate our approach.

2011 Information Theory and Applications Workshop, 2011

Implicit local coordination of nodes in a wireless network using mechanisms such as Carrier Sense... more Implicit local coordination of nodes in a wireless network using mechanisms such as Carrier Sense Multiple Access (CSMA) is conceptually attractive and relatively easy to implement, but often leads to performance that is far inferior to what is possible using explicit global coordination strategies such as Time Division Multiplexing (TDM). In this paper, we give two examples showing that appropriately designed implicit coordination strategies that employ learning and memory can provide performance competitive with that obtained using explicit strategies, while requiring minimal overhead. The first example is an algorithm for distributed timing synchronization maintenance using the timing information already present in ongoing communication in the network. The second example is a distributed medium access control protocol that achieves performance close to time division multiplexing (TDM) without requiring explicit resource allocation: nodes lock into communication patterns that have been found to work, with enough randomization to prevent locking into poor schedules. While the general philosophy of exploiting learning and memory in the design of network protocols is of broad applicability, our numerical results emphasize 60 GHz networks with highly directional links: effective coordination is particularly important for such networks, in view of the "deafness" caused by directionality.

Tropical Agriculture, Apr 1, 2002

The effect of etiolation on phenol content and polyphenol oxidase (PPO) activity at the precultur... more The effect of etiolation on phenol content and polyphenol oxidase (PPO) activity at the preculture stage and on post-culture phenolic exudation and explant survival was studied in shoot tips of eight mango (Mangifera indica L.) cultivars, viz., Amrapali, Mallika, Langra, Bhadauran, Tommy Atkins, Eldon, Sensation, and Alphonso. Etiolation treatment resulted in marked decline in PPO activity and phenol content at the pre-culture stage and phenolic exudation at the postculture stage, which in turn increased the explant survival in Murashige and Skoog's culture medium. Etiolated shoots had low PPO activity (0.496 ?A400 g-1 min-1) and phenol content (11.19 mg g-1 fresh tissue wt) at the pre-culture stage, exuded a smaller amount of phenols into the culture medium, and had higher explant survival (36.1%) compared to non-etiolated shoots, which had higher PPO activity (1.081 ?A400 g-1 min-1) and phenolic content (18.27 mg g-1 fresh tissue wt), exuded a greater amount of phenols into the medium (0.250 mg mLmedium), and had low survival of explants (7.7%). Among the cultivars, Bhadauran exhibited the highest PPO activity (1.468 ?A400 g-1 min-1) and phenol content (27.74 mg g-1 fresh tissue wt), exuded the greatest amount of phenols into the culture medium (0.340 mg mL-1 of medium), and had the minimum explant survival (3.4%) in contrast to Tommy Atkins, which exhibited the lowest PPO activity (0.582 ?A400 g-1 min-1) and phenol content (8.17 mg g-1 fresh tissue wt), exuded the smallest amount of phenols into the medium (0.095 mg mL-1 of medium), and had the highest explant survival (38.6%). Explant survival, in general, was very high (59.0%) initially (3rd day after culture initiation) but declined drastically thereafter to 0.9% after the 21st day of culture. The interactions between etiolation x cultivar, etiolation x time, cultivar x time, and etiolation x cultivar x time, were significant for explant survival. A strong positive correlation existed between PPO activity and phenol exudation (r = 0.912) and phenol content and exudation (r = 0.892), whereas the correlations between PPO activity and explant survival (r = -0.872) and phenol content and explant survival (r = -0.899) were strongly negative.

Energy, Nov 1, 2017

This work aims at proposing a sliding mode observer (SMO) based nonlinear multivariable sliding m... more This work aims at proposing a sliding mode observer (SMO) based nonlinear multivariable sliding mode controller (SMC) and globally linearizing controller (GLC) for a proton exchange membrane fuel cell (PEMFC). First, a nonlinear dynamic model of a methanol reformer is developed to produce hydrogen for the PEMFC. The reformer model has been verified and then its parameter values are modified to scale-up the reformer for fitting with a real time fuel cell. Subsequently, a nonlinear PEMFC model is formulated and validated with experimental data. The SMC consists of a controller and an estimator, whereas the GLC consists of a transformer, an estimator and a dual-loop external proportional integral (PI) controller. A transformer that relates the manipulated variable with the external control output is developed using the differential geometry. For both the control schemes, a nonlinear sliding mode observer is formulated to avoid any additional requirement of sensor to measure other than the controlled variables. Chattering occurred in the SMO and SMC due to very large frequency stroke of the sign function to minimize the estimation error has been eliminated by using a saturation function. Finally, the proposed SMO based SMC and GLC structure are tested for the integrated methanol reformer-PEMFC system. Observing an excellent estimation performance of the SMO, we investigate a comparative performance between the SMC and GLC with reference to a dual-loop PI controller.

IEEE Journal of Solid-State Circuits

This article presents a single-stage single-ended (SE) and a multistage pseudo-differential casco... more This article presents a single-stage single-ended (SE) and a multistage pseudo-differential cascode low-noise amplifiers (D-LNA) with their center frequencies at 235 and 290 GHz, respectively. Both low-noise amplifiers (LNAs) are designed beyond half of the maximum frequency of oscillation (f max) in 130-nm SiGe BiCMOS technology with f t / f max of 300/450 GHz. Implications of gain-boosting and noise reduction techniques in cascode structure are analyzed and it is observed that beyond f max /2, these techniques do not provide desired benefits. The single-stage SE LNA is designed to ascertain the theoretical analysis, and the same analysis is further implemented in staggered tuned four-stage LNA. Single-stage SE LNA provides a small signal gain of 7.8 dB at 235 GHz with 50 GHz of 3-dB bandwidth by consuming 18 mW of power. Four-stage differential LNA gives 12.9 dB of gain at center frequency 290 GHz and 11.2 dB at 300 GHz by drawing 68 mA current from the 2-V supply. The 3-dB bandwidth of differential LNA is measured to be 23 GHz. Noise figure measurements of both LNAs are performed using a gain-method technique with their measured noise figure values of 11 and 16 dB, respectively. This work successfully demonstrates the possibility of using a Si-based process to implement amplifiers beyond f max /2. To the authors' best knowledge, the four-stage differential LNA achieves, without any gain-boosting technique, the highest gain at 2/3(f max) with decent noise figure performance in SiGe technology. Index Terms-High current model (HICUM), low-noise amplifiers (LNAs), maximum frequency of oscillation (f max), receivers, SiGe BiCMOS integrated circuits, sub-THz and THz integrated circuits, vertical bipolar intercompany model (VBIC).

2019 IEEE Nordic Circuits and Systems Conference (NORCAS): NORCHIP and International Symposium of System-on-Chip (SoC)

This paper presents an alternative interpretation to Groszkowski's effect, which states that the ... more This paper presents an alternative interpretation to Groszkowski's effect, which states that the oscillation frequency of a harmonic oscillator is shifted due to the higher harmonic currents flowing into the LC tank. Groszkowki's analysis starts by taking a strictly memoryless amplifier, to which he derives and expression for balance of reactive powers. Then he interprets the frequency shift as a matter of balance of reactive energy in the tank. Here we show that although a conductive amplifier is memoryless, it can still show phase shift at the fundamental tone. This is due to mixing of the fundamental and harmonics in the nonlinear i-v response of the amplifier. Now the new interpretation comes from the oscillation condition: if the amplifier shows phase shift, the tank needs to compensate it, and this causes the shift in the oscillation frequency. The mechanism is explained, analysed symbolically, and verified numerically.

Current Journal of Applied Science and Technology, 2020

Aims: To study the effect of different micronutrients and number of foliar spray on fruit quality... more Aims: To study the effect of different micronutrients and number of foliar spray on fruit quality and leaf nutrient content of peach. Study Design: The experiment comprised of seven treatments and conducted on seven years old plants in Randomized Block Design with three replications. Place and Duration of Study: The experiment was conducted at the experimental orchard of Department of Horticulture, CCS Haryana Agricultural University, Hisar during the year 2018. Methodology: The treatments included in the study consisted of three micro-nutrients [T1- ZnSO4 @ 0.2%, T2- ZnSO4 @ 0.3%, T3- FeSO4 @ 0.2%, T4- FeSO4 @ 0.3%, T5- Boric acid @ 0.1%, T6- Boric acid @ 0.2%, T7- Control (water spray)] each applied as foliar spray at different concentration as single and double spray. Results: The results showed that foliar spray of micronutrients significantly improved quality and leaf nutrient status in peach cv. Shan-e-Punjab. The foliar spray of FeSO4 @ 0.2% (T3) found to be the best treatmen...

Bulletin of the Iranian Mathematical Society, 2019

In this paper, we introduced relatively star-C-Hurewicz property in topological spaces following ... more In this paper, we introduced relatively star-C-Hurewicz property in topological spaces following the approach of Bonanzinga and Pansera (

IOSR Journal of Engineering, 2014

As the competition in market is growing at a very fast pace, one can survive in today's industria... more As the competition in market is growing at a very fast pace, one can survive in today's industrial world by adopting the philosophy of Lean Manufacturing. In order to stay competitive, producing cheaper products at a faster rate Lean Manufacturing would help the industry. This paper represents a case study of Die casting industry. This case study is used to illustrate the steps in implementation of lean manufacturing providing actual and very positive results. The implementation plan is based on five major areas of wastes including Defects, Inventory, Excessive material movement, Delay due to waiting and Inappropriate processing in a die casting industry. The suggested implementation plan is being sub divided into three phases.

International Journal of Computer Applications, 2011

The importance of Ad-hoc network is due to its nature of infrastructure-less and decentralization... more The importance of Ad-hoc network is due to its nature of infrastructure-less and decentralization. In Ad-hoc network some nodes can become a critical spot in the network as they forward the packets to most of their neighbors. These critical nodes can deplete their battery power earlier, because of excessive load and processing for data forwarding. These unbalanced loads turn to nodes failure, network partition and reduce the route lifetime and route reliability. Energy consumption issue is a vital research topic in wireless ad hoc networks, because wireless nodes in such networks operate on limited battery power. This model paper describes An Energy and Traffic Aware Routing approach as an extension of AODV algorithm for Ad hoc network, utilizing the high energy path based on Route Selection Function. Our proposed algorithm adapts existing AODV routing protocol to improve performance in terms of traffic load on node, energy conservation and other performance metrics. The purpose of Route Selection Function is to improve lifespan of Ad hoc network and corresponding effect on overall network performance.

Volume 2B: Advanced Manufacturing, 2013

Rubber parts find a wide range of applications in several industrial sectors. Machining of rubber... more Rubber parts find a wide range of applications in several industrial sectors. Machining of rubber to produce final parts is preferred over using the conventional molding methods for the economic advantage of prior. Because of the complexity in the machining of rubber, not much experimental research has been documented in this area. The present work thus aims at machining of rubber using conventional lathe machine fit with a conventional grinding tool. Nitrile rubber rolls having a Shore hardness value of 30 is used for the experimental purpose. Speed, feed rate, and depth of cut are considered as the input machining parameters, and the surface roughness is selected as the response variable. Taguchi's orthogonal array method is used for optimizing. Analysis of variance (ANOVA) is used to determine the significance of each parameter, and the regression analysis is used to develop the linear analytical predicting model. The result obtained indicate N 2 f 1 D 1 as the optimum condition. The linear model developed shows a very high degree of fitness and a very high degree of accuracy in prediction with an error of less than 1% between the experimental and predicted values of the surface roughness.

International Journal of Computer Applications, 2011

An important and essential issue for mobile ad-hoc networks (MANETs) is routing protocol design i... more An important and essential issue for mobile ad-hoc networks (MANETs) is routing protocol design i.e. a major technical challenge due to the dynamism of the network. The work of this paper is inspired by the thought of taking account of several factors in wireless mobile ad-hoc networks (MANETs) routing design in a unified way. The rational of our inspiration is that most of the enhancements in DYMO protocol have been based on one criteria i.e. shortest path considered or multipath. There are several works in other On-demand routing protocols which considered some factors in a unified way. Therefore, we propose a routing mechanism i.e. "EA-DYMO Energy Aware Dynamic MANET On demand". In this routing mechanism, we would consider both the traffic load and energy aware path in a unified way. In this paper, we are modifying route selection procedure by taking the ratio of the energy factor as well as the average traffic load for each path, analysis and simulation we will consider as our future work.

FEMS Immunology & Medical Microbiology, 2002

Immune responses appropriate for control of an intracellular pathogen are generated in mice infec... more Immune responses appropriate for control of an intracellular pathogen are generated in mice infected with Brucella abortus, shown by the ability of T cells to adoptively transfer resistance to naive mice. The infection nevertheless persists for months. It was hypothesized that one factor in maintaining the infection despite the presence of immune T cells was suboptimal expression of major histocompatibility complex (MHC) molecules on macrophages containing brucellae. This would allow B. abortus to elude detection by the host's immune system. To test this, B. abortus organisms expressing green fluorescent protein (GFP-Brucella) were constructed and three-color flow cytometry used to evaluate MHC expression on macrophages following in vitro or in vivo infection. When infected in vitro, the levels of MHC class I and class II expression on J774 macrophages containing GFP-Brucella were the same or higher than on macrophages without GFP-Brucella in the same cultures. Similarly, the MHC expression was higher on GFP þ peritoneal exudate cells following infection or phagocytosis of heat-killed GFP-Brucella than it was on uninfected peritoneal exudate cells. Following in vivo infection of mice the level of MHC class I and II expression on GFP þ cells in their spleens (the main site of infection) also tended to be as high as or higher than that on the GFP-negative cells. The only in vivo GFP þ cells that showed a decreased MHC expression was a population of splenic Mac1 þ cells recovered from interferon-Q gene-disrupted mice at the time of their death due to an overwhelming number of bacteria per spleen. Overall, it was concluded that decreased MHC expression is not a general principle associated with brucella infection of macrophages and thus not likely to contribute to maintenance of the chronic infection.

IEEE INFOCOM 2009, 2009

We investigate an architecture for multi-Gigabit outdoor mesh networks operating in the unlicense... more We investigate an architecture for multi-Gigabit outdoor mesh networks operating in the unlicensed 60 GHz "millimeter (mm) wave" band. In this band, the use of narrow beams is essential for attaining the required link ranges in order to overcome the higher path loss at mm wave carrier frequencies. However, highly directional links make standard MAC methods for interference management, such as carrier sense multiple access, which rely on neighboring nodes hearing each other, become inapplicable. In this paper, we study the extent to which we can reduce, or even dispense with, interference management, by exploiting the reduction in interference due to the narrow beamwidths and the oxygen absorption characteristic of the 60 GHz band. We provide a probabilistic analysis of the interference incurred due to uncoordinated transmissions, and show that, for the parameters considered, the links in the network can be thought of as pseudo-wired. That is, interference can essentially be ignored in MAC design, and the challenge is to schedule half-duplex transmissions in the face of the "deafness" resulting from highly directional links. We provide preliminary simulation results to validate our approach.

2011 Information Theory and Applications Workshop, 2011

Implicit local coordination of nodes in a wireless network using mechanisms such as Carrier Sense... more Implicit local coordination of nodes in a wireless network using mechanisms such as Carrier Sense Multiple Access (CSMA) is conceptually attractive and relatively easy to implement, but often leads to performance that is far inferior to what is possible using explicit global coordination strategies such as Time Division Multiplexing (TDM). In this paper, we give two examples showing that appropriately designed implicit coordination strategies that employ learning and memory can provide performance competitive with that obtained using explicit strategies, while requiring minimal overhead. The first example is an algorithm for distributed timing synchronization maintenance using the timing information already present in ongoing communication in the network. The second example is a distributed medium access control protocol that achieves performance close to time division multiplexing (TDM) without requiring explicit resource allocation: nodes lock into communication patterns that have been found to work, with enough randomization to prevent locking into poor schedules. While the general philosophy of exploiting learning and memory in the design of network protocols is of broad applicability, our numerical results emphasize 60 GHz networks with highly directional links: effective coordination is particularly important for such networks, in view of the "deafness" caused by directionality.