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Search Results: 1 - 10 of 601783 matches for " R. A. Chaudhry "
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Efficient Congestion Mitigation Using Congestion-Aware Steiner Trees and Network Coding Topologies
M. A. R. Chaudhry,Z. Asad,A. Sprintson,J. Hu
VLSI Design , 2011, DOI: 10.1155/2011/892310
Abstract: In the advent of smaller devices, a significant increase in the density of on-chip components has raised congestion and overflow as critical issues in VLSI physical design automation. In this paper, we present novel techniques for reducing congestion and minimizing overflows. Our methods are based on ripping up nets that go through the congested areas and replacing them with congestion-aware topologies. Our contributions can be summarized as follows. First, we present several efficient algorithms for finding congestion-aware Steiner trees that is, trees that avoid congested areas of the chip. Next, we show that the novel technique of network coding can lead to further improvements in routability, reduction of congestion, and overflow avoidance. Finally, we present an algorithm for identifying efficient congestion-aware network coding topologies. We evaluate the performance of the proposed algorithms through extensive simulations. 1. Introduction In almost any VLSI design flow, global routing is an essential stage that determines the signal interconnections. Therefore, the capability of the global router may significantly affect the design turn-around time. Moreover, the results of the global routing stage impact many circuit characteristics, such as power, timing, area, and signal integrity. Global routing poses major challenges in terms of the efficient computation of quality routes. In fact, most of the global routing problems, even special cases, tend to be NP complete [1, 2]. In the advent of smaller devices, a significant increase in the density of on-chip components results in a larger number of nets that need to be routed, which, together with more stringent routing constraints, results in increasing congestion and overflow. In this paper, we propose novel techniques for congestion avoidance and overflow reduction. Our methods are designed for the rip-up-and-reroute phase of the global routing stage. At this stage, all the nets have already been routed using a standard prerouting technique however some of the nets need to be rerouted due to high congestion and overflow. Our methods are based on ripping up nets that go through congested areas and replacing them with congestion-aware topologies. The proposed techniques facilitate even distribution of the routing load along the available routing areas. We propose efficient algorithms for finding congestion-aware Steiner trees that favor uncongested routes. In addition, we use the novel technique of network coding for further reduction of congestion and overflow avoidance. 1.1. Congestion-Aware
Osteogenic Cells Derived From Embryonic Stem Cells Produced Bone Nodules in Three-Dimensional Scaffolds
G. R. Chaudhry,D. Yao,A. Smith,A. Hussain
Journal of Biomedicine and Biotechnology , 2004, DOI: 10.1155/s111072430431003x
Abstract: An approach for 3D bone tissue generation from embryonic stem (ES) cells was investigated. The ES cells were induced to differentiate into osteogenic precursors, capable of proliferating and subsequently differentiating into bone-forming cells. The differentiated cells and the seeded scaffolds were characterized using von Kossa and Alizarin Red staining, electron microscopy, and RT-PCR analysis. The results demonstrated that ES-derived bone-forming cells attached to and colonized the biocompatible and biodegradable scaffolds. Furthermore, these cells produced bone nodules when grown for 3–4 weeks in mineralization medium containing ascorbic acid and beta-glycerophosphate both in tissue culture plates and in scaffolds. The differentiated cells also expressed osteospecific markers when grown both in the culture plates and in 3D scaffolds. Osteogenic cells expressed alkaline phosphatase, osteocalcin, and osteopontin, but not an ES cell-specific marker, oct-4. These findings suggest that ES cell can be used for in vitro tissue engineering and cultivation of graftable skeletal structures.
Osteogenic Cells Derived From Embryonic Stem Cells Produced Bone Nodules in Three-Dimensional Scaffolds
Chaudhry G. R.,Yao D.,Smith A.,Hussain A.
Journal of Biomedicine and Biotechnology , 2004,
Abstract: An approach for 3D bone tissue generation from embryonic stem (ES) cells was investigated. The ES cells were induced to differentiate into osteogenic precursors, capable of proliferating and subsequently differentiating into bone-forming cells. The differentiated cells and the seeded scaffolds were characterized using von Kossa and Alizarin Red staining, electron microscopy, and RT-PCR analysis. The results demonstrated that ES-derived bone-forming cells attached to and colonized the biocompatible and biodegradable scaffolds. Furthermore, these cells produced bone nodules when grown for 3–4 weeks in mineralization medium containing ascorbic acid and beta-glycerophosphate both in tissue culture plates and in scaffolds. The differentiated cells also expressed osteospecific markers when grown both in the culture plates and in 3D scaffolds. Osteogenic cells expressed alkaline phosphatase, osteocalcin, and osteopontin, but not an ES cell-specific marker, oct-4. These findings suggest that ES cell can be used for in vitro tissue engineering and cultivation of graftable skeletal structures.
Impact of Pesticide Applications in Cotton Agroecosystem and Soil Bioactivity Studies II: Nitrification Dynamics
Zafar Iqbal,Altaf Hussain,Muhammad R. Asi,Jamil A. Chaudhry
Pakistan Journal of Biological Sciences , 2001,
Abstract: Field experiments were conducted to study the effect of pesticide applications on soil nitrification dynamics in cotton agroecosystem. The pesticides either alone or in combination (mixture) were applied according to the normal agricultural application rates in test, farmer (with pesticide applications) and control (without pesticide applications) fields. Soil samples were collected before and after two days, following pesticide applications and at sowing, before pesticide application, after all pesticide applications, at harvest and at post harvest time during the crop seasons 1997-1999. Soils were incubated under laboratory conditions using ammonium sulfate as substrate. In 1997 crop season soil samples were incubated for 28 days with a substrate of 144 mgkg -1 soil while in 1998-1999 the incubation period was 14 days with substrate of 212 mgkg -1 soil. The soil samples were analyzed for total (NO2 + NO3) N content using steam-distillation method. Othofonprox, profenophos + cypermethrin and bifenthrin + endosulfan inhibited while, endosulfan, imidachloprid, methamidophos, endosulfan alongwith dimethoate, profenophos + alphmethrin, chlorpyrifos + tralomethrin + acetamiprid and cyhalothrin + profenophos + diafenthiuron stimulated the nitrification. All other pesticidal applications have no effect on this parameter. Samples collected at different intervals of time from all the fields in three years study showed no differences in nitrification from sowing to harvest. The variations observed, in general, being very week and transient and resulting in a recovery of nitrification.
A study on pattern of ocular injuries in Delhi
Malik S.R.K,Gupta A,Chaudhry S
Indian Journal of Ophthalmology , 1968,
Abstract:
Field Surgical Intervention of Bovine Actinomycosis
U. Farooq*, A. Qayyum, H. A. Samad, H. R. Chaudhry and N. Ahmad1
Pakistan Veterinary Journal , 2010,
Abstract: Actinomycosis, or lumpy jaw, is an important cause of economic losses in livestock because of its widespread occurrence and poor response to the routine clinical treatment. The present study describes a typical case of bovine actinomycosis in a seven-month pregnant Sahiwal heifer with a hard swelling on the middle of the maxilla bone at the level of the central molar teeth. Tentative diagnosis was made through clinical signs. After maturation of the swelling, the area was incised under local anesthesia and debridement of the wound was achieved by sharp surgical debridement and mechanical debridement. Pus, having the appearance of sulphur granules, was completely removed from the excised cavity, which was closed by applying mattress sutures. Adjunct therapy of broad-spectrum antibiotic was administered intramuscularly for five days as a post-operative measure. Catamnesis revealed that the healing was complete in 15 days with no recurrence and untoward consequences.
First-Principles Studies of Luminescence in Ce doped Inorganic Scintillators
A. Canning,A. Chaudhry,R. Boutchko,N. Gr?nbech-Jensen
Physics , 2010, DOI: 10.1103/PhysRevB.83.125115
Abstract: Luminescence in Ce doped materials corresponds to a transition from an excited state where the lowest Ce 5d level is filled to the ground state where a single 4f level is filled. We have performed theoretical calculations based on Density Functional Theory to calculate the ground state band structure of Ce-doped materials as well as the Ce3+ excited state. The excited state calculations used a constrained occupancy approach by setting the occupation of the Ce 4f states to zero and allowing the first excited state above them to be filled. These calculations were performed on a set of Ce doped materials that are known from experiment to be scintillators or non-scintillators to relate theoretically calculable parameters to measured scintillator performance. From these studies we developed a set of criteria based on calculated parameters that are necessary characteristics for bright Ce activated scintillators. Applying these criteria to about a hundred new materials we developed a list of candidate materials for new bright Ce activated scintillators. After synthesis in powder form one of these new materials (Ba2YCl7:Ce) was found to be a bright scintillator. This approach, involving first-principles calculations of modest computing requirements was designed as a systematic, high-throughput method to aid in the discovery of new bright scintillator materials by prioritization and down-selection on the large number of potential new materials.
First-principles study of luminescence in Eu$^{2+}$-doped inorganic scintillators
A. Chaudhry,R. Boutchko,S. Chourou,G. Zhang,N. Gr?nbech-Jensen,A. Canning
Physics , 2014, DOI: 10.1103/PhysRevB.89.155105
Abstract: Luminescence in Eu$^{2+}$ activated materials corresponds to a transition from an excited state where the lowest Eu 5$d$ level is filled with one electron (often called the (Eu$^{2+}$)$^*$ state) to the ground state with half-filled 4$f$ shell with seven electrons of the same spin. We have performed theoretical calculations based on Density Functional Theory to determine the ground state band structure of Eu-doped materials as well as study the (Eu$^{2+}$)$^*$ excited state. Calculations were performed on Eu doped materials, experimentally known to be either scintillators or non-scintillators, in order to relate theoretically calculable parameters to experimentally observed properties. Applying criteria previously developed for Ce-doped systems (A.Canning, A. Chaudhry, R. Boutchko and N. Gr\o{}nbech-Jensen, Phys. Rev. B Vol.83, 125115 (2011)) to new Eu-doped materials we developed a list of candidate materials for new bright Eu activated scintillators. Ba$_2$CsBr$_5$:Eu is an example of a new bright scintillator from our candidate list that has been synthesized in microcrystalline powder form. As discussed in our previous paper on Ce-doped materials this approach was designed as a systematic high-throughput method to aid in the discovery of new bright scintillator materials by prioritization and down-selection on the large number of potential new materials.
Control of transients in water distribution networks by H Control
Terra, M. H.;Reis, J. A. T. dos;Chaudhry, F. H.;Souza, R. Schiavetto de;
Journal of the Brazilian Society of Mechanical Sciences , 2002, DOI: 10.1590/S0100-73862002000400006
Abstract: in this work, a controller for regulating the transients in water distribution networks is established. the control technique is the h¥ control. the developed controller is applied to a water distribution network and the results of this application demonstrate that the technique allowed the establishment of a robust controller, capable of attenuating the disturbances in a suitable way, being effective in controlling the oscillations of the state variables in question.
Performance of Cement Containing Laterite as Supplementary Cementing Material
Abbas Bukhari, Z. S.,Chaudhry, A. H.,Iqbal, M. N.,Siddiqui, R. H.
Kemija u Industriji , 2013,
Abstract: The utilization of different industrial waste, by-products or other materials such as ground granulated blast furnace slag, silica fume, fly ash, limestone, and kiln dust, etc. as supplemen- tary cementing materials has received considerable attention in recent years. A study has been conducted to look into the performance of laterite as Supplementary Cementing Materials (SCM). The study focuses on compressive strength performance of blended cement containing different percentage of laterite. The cement is replaced accordingly with percentage of 2 %, 5 %, 7 % and 10 % by weight. In addition, the effect of use of three chemically different laterites have been studied on physical performance of cement as in setting time, Le-Chatlier expansion, loss on ignition, insoluble residue, free lime and specifically compressive strength of cement cubes tested at the age of 3, 7, and 28 days. The results show that the strength of cement blended with laterite as SCM is enhanced. Key words: Portland cement, supplementary cementing materials (SCM), laterite, compressive strength KUI – 6/2013 Received January 4, 2012 Accepted February 11, 2013
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