FRICTION MEASUREMENT IN PRECISION GLASS MOLDING

Extensive growth of state-of-the-art technologies has created a demand for high quality lenses and has driven the industry toward an inexpensive process for manufacturing of aspheric glass lenses called Precision Glass Molding (PGM). Finite Element Analysis (FEA) has been used to predict the right mold geometry. Having a realistic simulation to predict mold geometry depends on the correct model of material behavior and friction coefficient at elevated temperature. Finding the static and dynamic coefficient of friction experimentally between two flat surfaces at elevated temperature is the subject of this research. The equipment used in this study was originally designed for the Precision Glass Molding (PGM) process and was modified for friction measurement by using molds designed specifically for the friction test. The performance of this apparatus was validated using a steel-steel friction pair at room temperature and a steel-BK7 pair at elevated temperature. The frictional behavior of two different types of oxide glasses; BK7 and Soda-Lime-Silica glass have been studied. During trials at which the temperature is above the glass transition temperature, the results show the effect of glass viscoelasticity in the friction data. This effect is in the form of exponential increase in friction force data prior to the onset of sliding. Moreover, the effect of stick-slip phenomenon can be seen as a jump in the position data (in the order of microns in tangential direction). Coulomb\u27s Law has been used to calculate the friction coefficient. An average friction coefficient has been defined and calculated for some trials, providing a quantitative value for dynamic friction coefficient at different process parameters. The final part of the investigation involved using the Design of Experiment approach to include a broader range of processing parameters and do a sensitivity analysis to find the effect of temperature, normal force, feed rate, and surface finish on dynamic friction coefficient. The finding from the current investigation demonstrates reasonable changes in dynamic friction of glass due to its viscoelastic properties close to its transition temperature. These friction data can be used to improve the accuracy of simulations of the PGM process

One-pot synthesis of polyhydropyridine derivatives via Hantzsch four component condensation in water medium: Use of a recyclable Lewis acid [Ce(SO4)2.4H2O] catalyst

An efficient and eco-friendly method for the synthesis of polyhydroquinoline derivatives using Ce(SO4)2.4H2O as mild and heterogeneous Lewis acid catalyst via the Hantzsch reaction in very short reaction time is reported. A mixture of an appropriate aldehyde, dimedone, ethyl acetoacetate and malononitrile in the presence of the Ce(SO4)2.4H2O at reflux conditions in water based media resulted in good to excellent yields of the corresponding products. The catalyst can be used as selective for some aromatic aldehydes in the reaction conditions.KEY WORDS: Ce(SO4)2.4H2O, Polyhydroquinoline, Hantzsch reaction, Muticomponent reaction, Dihydropyridine Bull. Chem. Soc. Ethiop. 2012, 26(3), 461-465.DOI: http://dx.doi.org/10.4314/bcse.v26i3.16 &#160

A 41-Year-Old Woman with Seizure

The patient was a 41 year old woman that was brought to the emergency department (ED) by her husband following seizure. According to the relatives accompanying her, the seizure was of tonic-clonic type, had occurred one hour before presentation to ED, and had lasted 3 minutes. The patient had been drowsy for about 15 minutes after the end of the seizure. She had no history of head trauma and did not mention headache, nausea and vomiting, fever, vision problems or others. On presentation, amnesia regarding the things that happened was evident. In her history, she had a generalized tonic-clonic seizure 4 years back, regarding which she had not done proper follow up for taking necessary diagnostic measures and had not been treated with anti-epileptic medication. She had a history of surgery for removing cold thyroid nodule 20 years ago and was under calcium treatment for 15 years but she had decided to stop taking her medications since 5 year ago. She did not have a history of alcohol or drug abuse. The patient was conscious and awake on presentation and did not have any specific clinical complaints. Her vital signs on presentation were as follows:Blood Pressure = 120/70mmHg, Pulse Rate = 68/minute, Respiratory Rate = 16/minute, O2saturation= 98% at air room, Oral Temperature= 37°C, and bedside blood sugar in the normal range.In head and neck examination, the surgery scar was seen in the thyroid region. Examination of the thyroid also showed a nodular surface in palpation. Examination of the heart, lungs, abdomen and extremities did not have pathologic findings. Neurologic examinations including evaluation of cranial nerves, sense and power of the muscles, cerebellar examination and deep tendon reflexes were normal. Based on the opinion of the in-charge physician, anti-epileptic drugs were not prescribed at this stage. Laboratory tests including complete blood cell count, liver function tests (LFT), and level of blood sugar (BS), sodium, potassium, calcium, phosphorus, magnesium, urea and creatinine electrolytes were ordered. Considering the full consciousness of the patient and stability of vital signs and clinical examinations, by taking safety measures and accompanied by a nurse, the patient was referred to the radiology unit to undergo a brain computed tomography (CT) scan, the results of which are shown in figure 1

Two View Line-Based Motion and Structure Estimation for Planar Scenes

We present an algorithm for reconstruction of piece-wise planar scenes from only two views and based on minimum line correspondences. We first recover camera rotation by matching vanishing points based on the methods already exist in the literature and then recover the camera translation by searching among a family of hypothesized planes passing through one line. Unlike algorithms based on line segments, the presented algorithm does not require an overlap between two line segments or more that one line correspondence across more than two views to recover the translation and achieves the goal by exploiting photometric constraints of the surface around the line. Experimental results on real images prove the functionality of the algorithm

Optimal Operation of Power Distribution Feeders with Smart Loads

Distribution systems have been going through significant changes in recent years, moving away from traditional systems with low-level control toward smart grids with high-level control, with improved technologies in communications, monitoring, computation, and real-time control. In the context of smart grids, Demand Response (DR) programs have been introduced so that customers are able to control and alter their energy consumption in consideration with distribution system operators, with benefits accruing to both customers and Local Distribution Companies (LDCs). This thesis focuses on the integration of DR with the intelligent operation of distribution system feeders. Thus, it proposes a mathematical model of an unbalanced three-phase distribution system power flow, including different kinds of loads and other components of distribution systems. In this context, an unbalanced three-phase Distribution Optimal Power Flow (DOPF) model is proposed, which includes the models of lines, transformers, voltage-based loads, smart loads, Load Tap Changers (LTCs), and Switched Capacitors (SCs), together with their respective operating limits, to determine the optimal switching decisions for LTCs, SCs, and control signals for smart loads, in particular, Energy Hub Management System loads and Peaksaver PLUS loads. Hence, Neural-Network-based models of controllable smart loads, which are integrated into the DOPF model are proposed, developed, and tested. Since the DOPF model has different discrete variables such as LTCs and SCs, the model is a Mixed-Integer Non-Linear Programming (MINLP) problem, which presents a considerable computational challenge. In order to solve this MINLP problem without approximations and ad-hoc heuristics, a Genetic Algorithm (GA) is used to determine the optimal control decisions of controllable feeder elements and loads. Since the number of control variables in a realistic distribution system is large, solving the DOPF for real-time applications using GA is computationally expensive. Hence, a decentralized system with parallel computing nodes based on a Smart Grid Communication Middleware (SGCM) system is proposed. Using a "MapReduce" model, the SGCM system executes the DOPF model, communicates between the master and the worker computing nodes, and sends/receives data amongst different parts of the parallel computing system. When large number of nodes are involved, the SGCM system has a fast performance, is reliable, and is able to handle different fault tolerance levels with the available computing resources. The proposed approaches are tested and validated on a practical feeder with the objective of minimizing energy losses and/or energy drawn from the substation. The results demonstrate the feasibility of the developed techniques for real-time distribution feeder control, highlighting the advantages of integration of smart loads in the operation of distribution systems by LDCs

HPLC DETERMINATION OF PARTHENOLIDE AND APIGENIN CONTENTS VERSUS LABEL CLAIMS IN IRANIAN PRODUCTS

In this study parthenolide content of feverfew product (Tanamigraine capsule) and apigenin content of chamomile products (Chamomill drop, Kamisol solution, Prostatan drop, Prostatan tablet) were determined as effective compound by HPLC. Feverfew product was extracted by methanol/distilled de-ionized water (50: 50) and chamomile products by methanol. The HPLC operating conditions were C-18 reversed phase column (VP-ODS 250×4.6 mm, 5 mm), methanol/ distilled de-ionized water (60: 40) as the mobile phase at a flow rate of 1 ml/min and UV detection at 214 nm for parthenolide and 2% acetic acid: acetonitril with linear program 80 to 40 % of acetic acid 2% with a flow rate of 1 ml/min and UV detection at 275nm for apigenin. The amount of parthenolide and apigenin obtained in Tanamigraine capsules and chamomile products is 0.13- 016% and 0.04- 35% respectivel

Traumatic Dissection of Carotid Artery in a 34-Year-Old Patient Presenting to Emergency Department; a Case Report

دیسکسیون شریان های ناحیه گردن از جمله شریان کاروتید از جمله آسیب های عروقی متعاقب ترومای بلانت ناحیه گردن به شمار می روند. تظاهرات این عارضه معمولا تاخیری بوده و به شکل تظاهرات نورولوژیک خود را نشان می دهد. این عارضه در مجموع عامل حدود 2 درصد موارد انفارکت های مغزی است ولی 20 درصد علل استروک مغزی افراد زیر 45 سال می باشد. با هدف بحث و تاکید بر اهمیت این عارضه، در این مقاله به معرفی یک مورد از بروز دایسکسیون کاروتید مراجعه کننده به بخش اورژانس پرداخته ایم. بیمار خانم 34 ساله ای است که متعاقب همی پارزی چپ و دیزارتری و سردرد که از چند ساعت قبل شروع شده به بخش اورژانس آورده شد که 10 روز قبل سابقه بستری بدلیل تصادف و واژگونی ماشین داشت که بعد از انجام بررسی های لازم، با حال عمومی خوب ترخیص شده بود. در سی تی اسکن مغز شواهد انفارکت ایسکمیک تحت حاد در محدوده شریان مغزی میانی رویت شد. با توجه به سن بیمار و شواهد ایسکمی وسیع و شرح حال ترومای اخیر، با شک به دیسکسیون عروق گردنی جهت بیمار آنژیوگرافی انجام شد و تشخیص دیسکسیون شریان کاروتید مسجل گردید.Dissection of neck arteries including carotid artery is among the vascular injuries following blunt neck trauma. Manifestations of this injury are usually delayed and present as neurological problems. This injury is accountable for about 2% of cerebral infarctions but causes 20% of brain strokes in patients less than 45 years old. Aiming to discuss and emphasize the importance of this injury, in this article a case of carotid dissection presenting to emergency department (ED) is presented. The patient was a 34 year-old woman that visited ED following left hemiparesis, dysartery and headache that had initiated a few hours back. She had a history of hospital admission 10 days before due to car accident and rollover, and had been discharged with good general health following required examinations. In brain computed tomography (CT) scan, there was evidence of sub-acute ischemic infarction around the middle cerebral artery. Considering the age of the patient, evidence of wide ischemia and history of recent trauma, neck artery dissection was suspected and angiography was performed, which confirmed the diagnosis of carotid artery dissection.