Optimization of electric discharge machining using simulated annealing

This paper proposes an optimization methodology for the selection of best process parameters in electro-discharge machining. Regular cutting experiments are carried out on die-sinking machine under different conditions of process parameters. The system model is created using counter-propagation neural network using experimental data. This system model is employed to simultaneously maximize the material removal rate as well as minimize the surface roughness using simulated annealing scheme. Finally consistency of the method is tested with several initial trail values. Results are shown in the form of tables and figures.     

Sterigmatocystin: Incidence,fate and production by Aspergillus versicolor in Ras cheese

The occurrence, distribution, and stability of sterigmatocystin (STG) in Ras cheese were investigated. An incidence value for STG in market samples of Ras cheese was 35% with a mean value of 22.2 μg/kg. In experimental Ras cheese from milk contaminated with STG, 80% of the toxin was retained in the curd while 20% was found in the whey. The temperature for cheese ripening affected the toxin content. At 6 °C the toxin concentration was hardly affected, but at 20 °C the concentration was reduced by 16% after 90 days. In Ras cheese contaminated with spores of Aspergillus versicolor, toxin production started after 45 days of the ripening, reached a maximum after 90 days, and declined thereafter. Cow's milk favoured toxin formation in comparison with buffaloe's milk. Aged cheese (more than 6 months) inhibited toxin production.     

Stress concentration of terminating twins

Twins terminated within a crystal are the source of stress concentration. These stresses may be evaluated by a continuum, dislocation or atomistic model. A knowledge of these stresses is useful in the understanding of atom glide, rupture of atoms and motion of individual atoms near a twin. This paper is based on a presentation made at a symposium on “The Role of Twinning in Fracture of Metals and Alloys” held at the annual meeting of the AIME, St. Louis, Missouri, October 15\2-19, 1978, under the sponsorship of the Mechanical Metallurgy Committee of The Metallurgical Society of AIME.     

LOW TEMPERATURE FLOW CHARACTERISTICS OF SOME WAXY CRUDE OILS IN RELATION TO THEIR COMPOSITION : PART II EFFECT OF WAX COMPOSITION AND CONCENTRATION ON THE DEW AXED CRUDE OILS WITH / WITHOUT ADDITIVES

ABSTRACT

In this part of the work the effect of wax concentrations on the rheologica! properties of the dewaxed Duliajan (Assam) and Lingaia crude oils have been studied. The dewaxing of the crude oil was done by removing n-paraffins from the crude oil by urea adduction. The urea adducted n-paraffins concentrate-the wax- was characterized by its carbon number distribution. The urea non adducted oil portion - the denormalized crude oil (DNO)- was characterized for its pour point. The wax in different concentration was then added in the DNO and the change in the rheological properties like pour point, yield stress and plastic viscosity were studied using a Haake Rota Viscometer. The effect of carbon number distribution, i.e. the composition of the wax, on these rheological properties was also investigated. Four different commercial pour point depressanl additives have been used to study their effects on the pour point, yield stress and plastic viscosity of the reconstituted (wax mixed DNO) crude oils.

From this study it has been found that wax concentration and its composition are primarily responsible for the variation in the pour point of the DNO, and the DNO composition has a small effect. However, as seen in the Part I of this paper, the response of the pour point depressant additive in effecting the change in the pour point is primarily governed by the composition of the DNO. The additives have shown better response in the DNO having more aromatic concentrate, as has been found in the case of Duliajan (Assam) DNO.     

Wavelet-based energy features for glaucomatous image classification

Texture features within images are actively pursued for accurate and efficient glaucoma classification. Energy distribution over wavelet subbands is applied to find these important texture features. In this paper, we investigate the discriminatory potential of wavelet features obtained from the daubechies (db3), symlets (sym3), and biorthogonal (bio3.3, bio3.5, and bio3.7) wavelet filters. We propose a novel technique to extract energy signatures obtained using 2-D discrete wavelet transform, and subject these signatures to different feature ranking and feature selection strategies. We have gauged the effectiveness of the resultant ranked and selected subsets of features using a support vector machine, sequential minimal optimization, random forest, and na?ve Bayes classification strategies. We observed an accuracy of around 93% using tenfold cross validations to demonstrate the effectiveness of these methods.     

Tubercular mastitis: a pragmatic approach to its management

Six cases of tubercular granulomatous mastitis were studied retrospectively. Three of these six cases posed diagnostic difficulties because of a lack of caseation in granuloma on fine needle aspiration cytology. A pragmatic approach is described here that is based on the correlation of the clinical features with the cytological findings. All six cases improved on therapeutic trial of antitubercular treatment.     

Estimating the Performance of Free Space Optical Link Under Adverse Weather Conditions by Using Various Models

Free space optics (FSO), going to replace the present microwave communications in the future is gaining considerable attention as it supplies fruitful solutions to many complications like the last mile problem. Besides availing many advantages like high bandwidth, data rate, low bit error rate any communication system operating in free space undergoes a significant amount of degradation in its signal strength due to the atmospheric affects in its pathway. Similarly, an optical signal launched into free space will also interfere with its surroundings and may get impaired due to the presence of different climatic conditions like rain, fog, haze, snow, gas molecules etc. As FSO is a perfect line of sight communication it may also undergo the problems of outage due to obstructions (birds, base motion), scattering, beam dispersion etc. Precise prediction of the impairments (atmospheric affects) can result in an efficient and flawless communication system. Supporting the research on free space optics this paper mainly focuses on the performance analysis of free space optical link in the presence of rain considering the parameters like received optical power its corresponding electrical power, quality factor. The analysis was extracted with the help of simulation using Opti System software developed by Optiwave.

     

Detection of HTTP flooding attacks in cloud using fuzzy bat clustering

Cloud computing plays a major role in reducing the expenditure of infrastructural costs on the basis of pay per use model. Security is the major concern wherein detection of security attacks and crimes is very difficult. Due to the distributed nature of attacks and crimes in the cloud, there is a need for an efficient security mechanism. Traditional security mechanisms cannot be applied directly to identify the source of attack due to the dynamic changes in the cloud. Hypertext Transfer Protocol (HTTP) flooding attacks are identified by keeping track of all the activities of the virtual machine instances running in the cloud. It is hard to identify the source of an attack since an attacker deletes all the possible traces. So, in order to mitigate this issue, the proposed method reads the logs, extracts the relevant features and investigates HTTP flooding attacks by a grouping of similar input patterns using fuzzy bat clustering and determines the anomalous behavior using deviated anomalous score. The suspicious source is determined by finding the event correlation between the virtual machine instance issued by cloud service provider with the suspicious source list. The experimental results are compared with the existing approaches, viz., k-means clustering, fuzzy c-means clustering, bat clustering and Bartd method in which the proposed method determines the anomalies accurately with very few false alarm than existing approaches.

     

Coupled effects of gold electroplating and electrochemical discharge machining processes on the performance improvement of a capacitive accelerometer

Coupled effects of an electroplated gold layer and damper holes drilled by Electro Chemical Discharge Machining (ECDM) process on the performance improvement of a quad beam capacitive accelerometer is presented in this paper. A simple quad beam-proof mass configuration with its beams located symmetrically at the centre of all the edges of the proof mass and connected to an outer supporting frame is considered in the present study. For a fixed damping ratio, prime-axis sensitivity of the sensor is increased by the damper holes whereas an electroplated gold layer improves the prime-axis sensitivity, cross-axis sensitivity, and Brownian Noise Equivalent Acceleration (BNEA). Moreover, the increased weight of the proof mass due to an electroplated gold layer further reduces the damping of the device which in turn helps to increase the prime-axis sensitivity more. A new figure of merit called Performance Factor (PF), defined as the ratio of the product of the prime-axis sensitivity and resonant frequency to the cross-axis sensitivity at a fixed damping ratio of 0.7 is used as a quantitative index to evaluate the performance improvement caused by the coupled effects of gold electroplating and ECDM processes. Simulation results show that for a device with damper holes of 8 μm diameter and electroplated gold layer of dimensions 3,000 μm × 3,000 μm × 20 μm, the prime-axis sensitivity is increased by more than 500 times, rotational cross-axis sensitivity and BNEA are reduced by around 10 and 30%, respectively and the PF is improved by around 482 times at a fixed damping ratio of 0.7.