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匹配条件: “Singh Raman” ,找到相关结果约14601条。
A Note on the Effect of Negative Poisson’s Ratio on the Deformation of a Poroelastic Half-Space by Surface Loads  [PDF]
Sunita Rani, Raman Kumar, Sarva Jit Singh
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.26056
Abstract: The aim of this note is to study the effect of negative Poisson’s ratio on the quasi-static deformation of a poroelastic half-space with anisotropic permeability and compressible fluid and solid constituents by surface loads. Two particular cases considered are: two-dimensional normal strip loading and axisymmetric normal disc loading. It is found that a negative Poisson’s ratio makes the Mandel-Cryer effect more prominent. It also results in an increase in the magnitude of the surface settlement.
Selection of Material for Bicycle Chain in Indian Scenario using MADM Approach
Harwinder Singh,Raman Kumar
Lecture Notes in Engineering and Computer Science , 2012,
Y-haplotypes and idiopathic male infertility in an Indian population
Singh Kiran,Raman Rajiva
Indian Journal of Human Genetics , 2009,
Abstract: Infertility being a multifactorial disorder, both genetic and environmental factors contribute to the etiology of infertile phenotype. Chromosomal anomalies and Y-microdeletion are the established genetic risk factors of male infertility. Y-haplotypes has been found as risk factor for male infertility in certain populations, though in certain others no association has been reported, suggesting a population-specific association of these variations with male infertility. In a case-control study, 165 azoo-/oligospermic patients and 200 controls were haplotyped for certain Y-haplogroups for a possible association with idiopathic male infertility in an Indian population. Analysed Y-haplogroups showed no association with infertile phenotype. Thus this genetic factor is not a risk for infertility in the studied Indian population but that does not rule out the possibility of any of them, to be a risk in other populations.
A386G polymorphism of the DAZL gene is not associated with idiopathic male infertility in North India
Singh Kiran,Raman Rajiva
Journal of Human Reproductive Sciences , 2009,
Abstract: Background: Male infertility is a multifactorial disorder which affects approximately 10% of couples at childbearing age with substantial clinical and social impact. Genetic variation and environmental factors contribute to susceptibility to spermatogenic impairment in humans. The A386G (T54A) polymorphism of the autosomal gene, DAZL, has shown susceptibility to spermatogenic failure in Taiwanese population. However, no such association has been seen in infertile patients from Italy and South India. Aim: This study aims to find out the possible association between A386G (T54A) polymorphism of the autosomal gene, DAZL and idiopathic male infertility in patients from North India. DESIGN: Case-control study. Materials and Methods: The prevalence of A386G (T54A) polymorphism was determined in 165 idiopathic infertile azoo-/oligospermic patients and 200 fertile healthy control men. PCR-RFLP analysis was employed to determine the genotypes. PCR amplicons were subjected to restriction digestion with AluI as this mutation created a restriction site (AGCT), and separated on a 12% polyacrylamide gel. Results: Analysis of 165 idiopathic infertile azoo-/oligospermic and 200 fertile control men revealed only one case of the variant as a heterozygote in the control population. Single Nucleotide Polymorphism (SNP) was absent in the infertile patients. Conclusion: As in the report from Italy and South India, our results illustrate the rarity of this mutation. Apparently, this mutation is of recent origin and/or has poor selective value. Its preponderance in infertile patients from Taiwan (all heterozygotes) suggests a founder effect and also that its low selective value could be due to impaired spermatogenesis.
A Dynamic Bandwidth Assignment Approach Under DDoS Flood Attack
Raman Singh,Amandeep Verma
Journal of Advances in Information Technology , 2012, DOI: 10.4304/jait.3.2.120-129
Abstract: Distributed denial-of-service (DDoS) attacks are a major threat to the Internet. A lot of research is going on to detect, prevent and trace back DDoS attacks. Most of researchers are busy in post attack forensics which comes after the attack has been occurred but nobody is talking about how to design a system which can tolerate such attacks. In this paper we have suggested a approach for dynamic assignment of bandwidth in order to sustain the server. Basic idea is to examine genuine IP user’s traffic flow based on volume. Divide traffic in two categories of genuine traffic and malicious traffic and assign bandwidth as per category. The idea is to design a system which can give services even when the server is under attack. However some performance will degrades but overall Quality of services will be acceptable. A new formula also has been derived for dynamic bandwidth assignment which is based on number of genuine users and traffic volumes of users and attackers.
Analysis The Effects Of Process Parameters In En24 Alloy Steel During Cnc Turning By Using Madm
International Journal of Innovative Research in Science, Engineering and Technology , 2013,
Abstract: Much of modern day machining is carried out by computer numerical control (CNC). In this research work an attempt has been made to analysis the effects of input parameters such as speed (rpm), feed (mm/rev), depth of cut (mm) and nose radius (mm) on output parameter such as material removal rate and surface roughness. The experiment was performed with different combination values of input parameter. Equal weightage has been assigned to all input parameter and a (Multi attribute decision making) MADM approach then performed to find out the best result.
MTHFR A1298C polymorphism and idiopathic male infertility
Singh K,Singh S,Raman R
Journal of Postgraduate Medicine , 2010,
Abstract: Background : DNA methylation is an important epigenetic feature of DNA that plays a pivotal role in gene expression regulation during spermatogenesis. The enzyme methylenetetrahydrofolate reductase (MTHFR) catalyses the formation of folate intermediates that are vital for DNA synthesis and methylation reactions. C677T and A1298C variants of MTHFR result in reduced plasma folate and increase the susceptibility to various multifactorial disorders. We have already shown that homozygosity for 677 (C T) mutation in the MTHFR gene, is a risk factor for idiopathic male infertility in an Indian population. Aim: Recently, we showed that homozygosity for the 677(C T) mutation in the MTHFR gene is a risk factor for idiopathic male infertility and now we aim to assess whether the A1298C mutation in the same gene is an additional risk factor for idiopathic male infertility in an Indian population. Setting and Designs : In a case-control study 151 idiopathic male infertile patients and 140 healthy fertile control individuals were recruited from the University hospital and infertility clinics in Varanasi city, India. Materials and Methods: Genotyping for A1298C change of the MTHFR gene was done by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Statistical Analysis : Allele frequencies were calculated using Fisher′s exact test. Odds ratio was calculated as the measure of the association between the MTHFR genotype and idiopathic male infertility. Results : The homozygous (C/C) A1298C polymorphism of the MTHFR gene was present at a statistically high significance in idiopathic azoospermic infertile men (OR=3.4494, CI: 1.0092 to 11.7899, P<0.05). Conclusion : The MTHFR 1298CC genotype is an additional genetic risk factor for idiopathic male infertility in an Indian population.
Mechanical Properties of Polymer Concrete
Raman Bedi,Rakesh Chandra,S. P. Singh
Journal of Composites , 2013, DOI: 10.1155/2013/948745
Abstract: Polymer concrete was introduced in the late 1950s and became well known in the 1970s for its use in repair, thin overlays and floors, and precast components. Because of its properties like high compressive strength, fast curing, high specific strength, and resistance to chemical attacks polymer concrete has found application in very specialized domains. Simultaneously these materials have been used in machine construction also where the vibration damping property of polymer concrete has been exploited. This review deals with the efforts of various researchers in selection of ingredients, processing parameters, curing conditions, and their effects on the mechanical properties of the resulting material. 1. Introduction Polymer concrete is a composite material which results from polymerization of a monomer/aggregate mixture. The polymerized monomer acts as binder for the aggregates and the resulting composite is called “Concrete.” The developments in the field of polymer concrete date back to the late 1950s when these materials were developed as replacement of cement concrete in some specific applications. Early usage of polymer concrete has been reported for building cladding and so forth. Later on because of rapid curing, excellent bond to cement concrete and steel reinforcement, high strength, and durability, it was extensively used as repair material [1]. Precast polymer concrete has been used to produce a variety of products like acid tanks, manholes, drains, highway median barriers, and so forth. The properties of polymer concrete differ greatly depending on the conditions of preparation. For a given type of polymer concrete, the properties are dependent upon binder content, aggregate size distribution, nature and content of the microfiller, curing conditions, and so forth [2]. The most commonly used resins for polymer concrete are unsaturated polyester resin, methyl methacrylate, epoxy resins, furan resins, polyurethane resins, and urea formaldehyde resin [3]. Generally, more than 75–80% volume in polymer concrete is occupied by the aggregates and fillers. The aggregates are normally taken as inert materials dispersed throughout the polymer matrix. Normally aggregates are added in two size groups, that is, coarse aggregates comprising material of more than 5?mm size and fine aggregates having size less than 5?mm. The grading of aggregates in the case of polymer concrete is nonstandardized till date and varies widely from system to system. In addition to the coarse and fine aggregates, microfillers are also added sometimes to the polymer concrete
Flexural Fatigue-Life Assessment and Strength Prediction of Glass Fibre Reinforced Polymer Concrete Composites
Raman Bedi,S. P. Singh,Rakesh Chandra
ISRN Materials Science , 2014, DOI: 10.1155/2014/928278
Abstract: The paper presents the results of an investigation conducted to assess the fatigue-life and prediction of flexural fatigue strength of polymer concrete composites based on epoxy resin as binder material. Three point flexural fatigue tests were conducted on polymer concrete specimens using MTS servo controlled actuator, to obtain the fatigue lives of the composites at different stress levels. One hundred and thirty-seven specimens of size ?mm were tested in flexural fatigue. Forty-three static flexural tests were also conducted to facilitate fatigue testing. It has been observed that the probabilistic distribution of fatigue-life of polymer concrete composite (PCC) and glass fibre reinforced polymer concrete composite (GFRPCC), at a particular stress level, approximately follows the two-parameter Weibull distribution, with statistical corelation coefficient values exceeding 0.90. The fatigue strength prediction model, representing S-N relationship, has been examined and the material coefficients have been obtained for GFRPCC containing 0.5% and 1.0% glass fibres. Design fatigue lives for GFRPCC containing different contents of glass fibres have been estimated for acceptable probabilities of failure and compared with those of PCC. 1. Introduction Polymer concrete composites (PCC) have been in use in the domain of civil engineering since the 1960s for various applications. Later on, due to its better properties, the material has been utilized extensively for applications such as pump base plates and machine tool bases, and so forth. Recent studies on machine tools having bases made of PCC and glass fibre reinforced polymer concrete composite (GFRPCC) have concluded that components manufactured on these have better surface finish and tolerance when compared to those with cast iron bases [1–3]. The most important reason for this is the vibration damping capability of PCC and GFRPCC which is significantly higher than conventional machine building materials like cast iron [4–6]. Fatigue loading is inevitable in these applications and, therefore, accurate characterization of fatigue behaviour of PCC and GFRPCC is of immense importance. Studies on fatigue behaviour of PCC have been reported in literature [7–9], but a small number of specimens have been tested in most of these studies and fatigue-life distributions for PCC have not been reported. It is pertinent to note that in investigations wherein the probabilistic analysis of the fatigue data is the prime objective, it is desirable to test relatively large number of specimens at a given stress level to obtain
Sampling Based Approaches to Handle Imbalances in Network Traffic Dataset for Machine Learning Techniques
Raman Singh,Harish Kumar,R. K. Singla
Computer Science , 2013, DOI: 10.5121/csit.2013.3704
Abstract: Network traffic data is huge, varying and imbalanced because various classes are not equally distributed. Machine learning (ML) algorithms for traffic analysis uses the samples from this data to recommend the actions to be taken by the network administrators as well as training. Due to imbalances in dataset, it is difficult to train machine learning algorithms for traffic analysis and these may give biased or false results leading to serious degradation in performance of these algorithms. Various techniques can be applied during sampling to minimize the effect of imbalanced instances. In this paper various sampling techniques have been analysed in order to compare the decrease in variation in imbalances of network traffic datasets sampled for these algorithms. Various parameters like missing classes in samples, probability of sampling of the different instances have been considered for comparison.

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