130 research outputs found
Quantitative Modeling of Entangled Polymer Rheology: Experiments, Tube Models and Slip-Link Simulations.
Rheology properties are sensitive indicators of molecular structure and dynamics. The relationship between rheology and polymer dynamics is captured in the constitutive model, which, if accurate and robust, would greatly aid molecular design and polymer processing. This dissertation is thus focused on building accurate and quantitative constitutive models that can help predict linear and non-linear viscoelasticity. In this work, we have used a multi-pronged approach based on the tube theory, coarse-grained slip-link simulations, and advanced polymeric synthetic and characterization techniques, to confront some of the outstanding problems in entangled polymer rheology.
First, we modified simple tube based constitutive equations in extensional rheology and developed functional forms to test the effect of Kuhn segment alignment on a) tube diameter enlargement and b) monomeric friction reduction between subchains. We, then, used these functional forms to model extensional viscosity data for polystyrene (PS) melts and solutions. We demonstrated that the idea of reduction in segmental friction due to Kuhn alignment is successful in explaining the qualitative difference between melts and solutions in extension as revealed by recent experiments on PS.
Second, we compiled literature data and used it to develop a universal tube model parameter set and prescribed their values and uncertainties for 1,4-PBd by comparing linear viscoelastic G’ and G” mastercurves for 1,4-PBds of various branching architectures. The high frequency transition region of the mastercurves superposed very well for all the 1,4-PBds irrespective of their molecular weight and architecture, indicating universality in high frequency behavior. Therefore, all three parameters of the tube model were extracted from this high frequency transition region alone.
Third, we compared predictions of two versions of the tube model, Hierarchical model and BoB model against linear viscoelastic data of blends of 1,4-PBd star and linear melts. The star was carefully synthesized and characterized. We found massive failures of tube models to predict the terminal relaxation behavior of the star/linear blends. In addition, these blends were also tested against a coarse-grained slip-link model, the “Cluster Fixed Slip-link Model (CFSM)” of Schieber and coworkers. The CFSM with only two parameters gave excellent agreement with all experimental data for the blends.PHDMacromolecular Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/120764/1/psdesai_1.pd
Review on Strain Monitoring of Aircraft Using Optical Fibre Sensor
Structural health monitoring of aircraft assures safety, integrity and reduces cost-related concerns by reducing the number of times maintenance is required. Under aerodynamic loading, aircraft is subjected to strain, in turn causing damage and breakdown. This paper presents a review of experimental works, which focuses on monitoring strain of various parts of aircraft using optical fibre sensors. In addition, this paper presents a discussion and review on different types of optical fibre sensors used for structural health monitoring (SHM) of aircraft. However, the focus of this paper is on fibre bragg gratings (FBGs) for strain monitoring. Here, FBGs are discussed in detail because they have proved to be most viable and assuring technology in this field. In most cases of strain monitoring, load conditioning and management employs finite element method (FEM). However, more effort is still required in finding the accurate positions in real time where the sensors can be placed in the structure and responds under complex deformation
Prediction Of Study Track Using Decision Tree
ABSTRACT One of the most important issues to succeed in academic life is to assign students to the right track when they arrive at the end of basic education stage. The education system is graded from 1 st to 10 th standard, where after finishing the 10 th grade the student's are distributed into different academic tracks or fields such as Science, Commerce, Arts depending on the marks that they have scored. In order to succeed in academic life the student should select the correct academic field. Many students fail to select the appropriate field. At one instant of time they prefer a certain type of career and at the next instant they consider another option. To improve the quality of education data mining techniques can be utilized instead of the traditional process. The proposed system has many benefits as compared to traditional system as the accuracy of results is better. The problems can be solved via the proposed system. The proposed system will predict the streams through the decision tree method. With each and every input the proposed system evolves with better accuracy
Cytopathological study of salivary gland lesions by fine needle aspiration cytology
Background: Fine needle aspiration cytology is an inexpensive, minimally invasive, outpatient diagnostic procedure. FNA of salivary gland is easier to perform as the site is superficial and repeat FNAC can be perform. As compared to biopsy methods, FNA is a very smooth, cheaper, outpatient procedure helping clinician to save his time for earlier diagnosis and treatment. Though anatomical structure of the gland is very simple, it is subjected to a diverse and heterogenous range of tumors.Methods: The present study on “Cytomorphological features of salivary gland lesion by FNAC” was carried out on department of pathology from June 2015 to June 2017. 65 patients with salivary gland lesions who were sent to pathology department for FNAC were aspirated and correlated histopathologically.Results: Benign salivary gland lesions contribute to majority of cases (54%). Pleomorphic Adenoma was the most common benign salivary gland lesions and Mucoepidermoid Carcinoma was most common malignant lesion. Parotid gland was the most commonly involved in benign tumors and submandibular gland was commonly involved by malignant tumors. Commonly affected age group by benign salivary gland lesion was 31-40 years and those with malignant salivary gland lesion was 41-50 years.Conclusions: FNA cytology provides useful information for the management of salivary gland lesions and prevents unnecessary surgery in cases of nonneoplastic lesions and identification of malignancy helps the surgeon in deciding type and extent of surgery
Regulatory Privacy Practices in Europe
In today’s global economy, the flow of information is essential for the growth of international commerce and for the cross border access for both B2B and B2C services. The e-commerce phenomenon has elevated the privacy issue to a global platform. This paper examines the extent to which sample firms in four European countries post privacy notices on their websites. While posted privacy policy does not necessarily mean compliance with privacy protection policy, the absence of it indicates failure to comply with the most basic principle of privacy protection. We also reviewed the posted privacy policies of 425 firms and evaluated them against their corresponding country’s directives as well as fair information policies of the US. Descriptive statistics from the collected data provide a preliminary indication of how privacy practices are observed in our samples of four European countries
Pyometra in the postpartum: a forgotten complication
We report a case of 37 years old women who conceived after in vitro fertilization (IVF). Her antenatal course was uneventful. On delivery there was placenta acreta. She later presented in the postpartum period with pyometra. She was managed with conservative treatment. We believe that the placental bed sutures and the sloughing placenta could have led to sterile pyometra in this patient. This rare but important complication need to be kept in mind specially in high risk women with thin endometrium, h/o IVF, cervical encerclage, and placenta acreta
Thermally Comfortable Affordable Housing: A Study on Residential Building Code In India
On an average, India has more than 3000 Cooling Degree Days (CDD). The multifamily public housing being constructed under India’s Prime Minister Awas Yojana (PMAY) is aimed at providing formal housing to the society’s Economic Weaker Section (EWS). It is essential that this housing delivers thermally comfortable in-doors to the occupants. This study mapped the design and construction practices followed under PMAY Urban (PMAY-U) against India’s Residential Energy Building Code, Eco Niwas Samhita (ENS). The metric prescribed in ENS is Residential Envelope Transmittance Value (RETV). For 80 PMAY-U projects, information related to spatial design, and walling assemblies was collated. 30 projects were short-listed for detailed analysis. The RETV for selected projects was calculated. The analysis demonstrated that walling assemblies and technologies having a lower thermal transmittance value (U-value) resulted in meeting the ENS prescribed RETV numbers, hence, code compliance. The study further extended to assess the energy performance of the housing unit by exploring the change in walling assemblies. The change in thermally comfortable hours were reported in the range of 4145 and 6034, and Energy Performance Index (EPI) of the dwelling units were reported between 64 and 68 kWh/m2/year for the various walling assemblies
Investigation of Different Transfer Functions for Optical Limiting Amplifier used in a 2R Burst Mode Optical Regenerator
The major difference between a continuous mode optical regenerator (CMOR) and a burst mode optical regenerator (BMOR) is that a BMOR is capable of handling large variations in the input power which makes it useful in optical packet switched and optical burst switched networks. This is due to the optical limiting amplifier (OLA) present in the BMOR. Using computer modelling, the impact of using different OLA non-linear transfer functions on the output bit error rate of a system consisting of a cascade of 2R BMORs has been investigated. The effect of amplified spontaneous emission (ASE) noise introduced in the inter-regenerator links has also been taken into consideration.
Production of Biodiesel using waste temple oil from Shani Shingnapur temple (Dist. Ahmednagar), Maharashtra, India using chemical and biological methods
In India, due to various mythological and religious reasons hundreds of devotees pour oil over the idols in Hanuman or Maruti and Shani temples. The oil once poured cannot be reutilized and was ultimately wasted. These waste temple oil from Shani Shingnapurwas used to produce biodiesel. Immobilized Pseudomonas aeruginosa was used to catalyze transesterification of waste temple oil. The cells of P.aeruginosa were immobilized within the sodium alginate. Biodiesel production and its applications were gaining popularity in recent years due to decreased petroleum based reserves. Biodiesel cost formed from waste temple oil was higher than that of fossil fuel, because of high raw material cost.To decrease the cost of biofuel, waste temple oil was used as alternative as feedstock. It has lower emission of pollutants; it is biodegradable and enhances engine lubricity. Waste temple oil contains triglycerides that were used for biodiesel production by chemical and biological method.Transesterification reaction of oil produces methyl esters that are substitutes for fatty acid alkyl biodiesel fuel. Characteristics of oil were studied such as specific gravity, viscosity, acid number, saponification number.Parameters such as temperature,oil: methanol ratio were studied and 88%, 96% of biodiesel yield was obtained with effect of temperature and oil: methanol ratio on transesterification reaction. Withaddition ofNaOH or KOH to fatty acids which formed salt known as soap,which is excellent emulsifying and cleaning agents
Keystroke Biometric: Receiver Operating Characteristics (ROC) Experiments
Abstract In biometric authentication systems the Receiver Operating Characteristic (ROC
- …