Optimization of Multiple Responses of Ultrasonic Machining (USM) Process: A Comparative Study

Ultrasonic machining (USM) process has multiple performance measures, e.g. material removal rate (MRR), tool wear rate (TWR), surface roughness (SR) etc., which are affected by several process parameters. The researchers commonly attempted to optimize USM process with respect to individual responses, separately. In the recent past, several systematic procedures for dealing with the multi-response optimization problems have been proposed in the literature. Although most of these methods use complex mathematics or statistics, there are some simple methods, which can be comprehended and implemented by the engineers to optimize the multiple responses of USM processes. However, the relative optimization performance of these approaches is unknown because the effectiveness of different methods has been demonstrated using different sets of process data. In this paper, the computational requirements for four simple methods are presented, and two sets of past experimental data on USM processes are analysed using these methods. The relative performances of these methods are then compared. The results show that weighted signal-to-noise (WSN) ratio method and utility theory (UT) method usually give better overall optimisation performance for the USM process than the other approaches

Feature-based decision rules for control charts pattern recognition: A comparison between CART and QUEST algorithm

Control chart pattern (CCP) recognition can act as a problem identification tool in any manufacturing organization. Feature-based rules in the form of decision trees have become quite popular in recent years for CCP recognition. This is because the practitioners can clearly understand how a particular pattern has been identified by the use of relevant shape features. Moreover, since the extracted features represent the main characteristics of the original data in a condensed form, it can also facilitate efficient pattern recognition. The reported feature-based decision trees can recognize eight types of CCPs using extracted values of seven shape features. In this paper, a different set of seven most useful features is presented that can recognize nine main CCPs, including mixture pattern. Based on these features, decision trees are developed using CART (classification and regression tree) and QUEST (quick unbiased efficient statistical tree) algorithms. The relative performance of the CART and QUEST-based decision trees are extensively studied using simulated pattern data. The results show that the CART-based decision trees result in better recognition performance but lesser consistency, whereas, the QUEST-based decision trees give better consistency but lesser recognition performance

Comparison of efficacy between intravenous clonidine and dexmedetomidine as pre-medication in attenuating hemodynamic stress responses during laparoscopic cholecystectomy

Background: Laparoscopic cholecystectomy is a commonly performed surgery and stable intraoperative hemodynamic status is desirable during pneumoperitonium. Clonidine and dexmedetomidine (alpha-2 adrenergic agonist) were used in this study to attenuate the stress response of pneumoperitoneum because alpha-2 adrenergic agonists help in the attenuation of neuroendocrine and hemodynamic responses to surgery and anesthesia, due to its sympatholytic action. Aims and Objectives: The aims and objectives of the study are to conduct a comparative evaluation of clonidine and dexmedetomidine as pre-anesthetic medication for the attenuation of hemodynamic changes during laparoscopic cholecystectomy surgeries. Materials and Methods: Eighty patients of either sex, aged 20–50 years, complying to the American Society of Anesthesiologists physical status I-II, scheduled for elective laparoscopic cholecystectomy under general anesthesia were divided into two equal groups to receive either clonidine 1 mg/kg (Group-C, n=40) or dexmedetomidine 1 mg/kg (Group-D, n=40), both injected through intravenous route as 15 mL volume with normal saline. Heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, and SpO2 were measured before and after giving the study drugs, before and immediately after pneumoperitoneum, and then, at 10, 20, 30, 40, and 50 min of pneumoperitoneum. Results: Statistically significant difference was observed in heart rate in the dexmedetomidine group constantly since giving study drug, immediately after the creation of pneumoperitoneum, and then, 10, 20, 30, 40, and 50 min after pneumoperitoneum. Systolic, diastolic, and mean blood pressures were found to be significantly lower in Group D (except after administering study drug), immediately after creating pneumoperitoneum, and 10, 20, 30, 40, and 50 min after pneumoperitoneum. Conclusion: Dexmedetomidine as pre-medication is more efficacious in attenuating hemodynamic stress responses in laparoscopic cholecystectomy surgeries compared to clonidine as pre-medication

Deregulation of LIMD1-VHL-HIF-1α-VEGF pathway is associated with different stages of cervical cancer.

To understand the mechanism of cellular stress in basal-parabasal layers of normal cervical epithelium and during different stages of cervical carcinoma, we analyzed the alterations (expression/methylation/copy number variation/mutation) of HIF-1α and its associated genes LIMD1, VHL and VEGF in disease-free normal cervix (n = 9), adjacent normal cervix of tumors (n = 70), cervical intraepithelial neoplasia (CIN; n = 32), cancer of uterine cervix (CACX; n = 174) samples and two CACX cell lines. In basal-parabasal layers of normal cervical epithelium, LIMD1 showed high protein expression, while low protein expression of VHL was concordant with high expression of HIF-1α and VEGF irrespective of HPV-16 (human papillomavirus 16) infection. This was in concordance with the low promoter methylation of LIMD1 and high in VHL in the basal-parabasal layers of normal cervix. LIMD1 expression was significantly reduced while VHL expression was unchanged during different stages of cervical carcinoma. This was in concordance with their frequent methylation during different stages of this tumor. In different stages of cervical carcinoma, the expression pattern of HIF-1α and VEGF was high as seen in basal-parabasal layers and inversely correlated with the expression of LIMD1 and VHL. This was validated by demethylation experiments using 5-aza-2'-deoxycytidine in CACX cell lines. Additional deletion of LIMD1 and VHL in CIN/CACX provided an additional growth advantage during cervical carcinogenesis through reduced expression of genes and associated with poor prognosis of patients. Our data showed that overexpression of HIF-1α and its target gene VEGF in the basal-parabasal layers of normal cervix was due to frequent inactivation of VHL by its promoter methylation. This profile was maintained during different stages of cervical carcinoma with additional methylation/deletion of VHL and LIMD1.This work was supported by CSIR (Council of Scientific and Industrial Research, Government of India)-JRF/NET grant [File No.09/030(0059)/2010-EMR-I] to Mr. C.Chakraborty, grant [Sr. No. 2121130723] from UGC (University Grants Commission, Government of India) to Mr. Sudip Samadder, grant [SR/SO/HS-116/2007] from DST (Department of Science and Technology, Government of India) to Dr. C. K. Panda and grant [ No. 60(0111)/14/EMR-II of dt.03/11/2014] from CSIR (Council of Scientific and Industrial Research, Government of India) to Dr. C. K. Pand

Valorisation of toxic paper mill waste through vermicomposting: An insight towards cleaner engineering through alleviation of wastes

Valorisation involves conversion of toxic compounds into value added products. The present study has tried to evaluate the potential of vermicomposting in management of different types of toxic paper mill wastes such as primary waste (VCP) and secondary waste (VCS) using Eisenia fetida for 60 days. The procedure was performed using sundried samples of paper mill wastes, cow dung and straw in different trial sets using different ratios. The study had revealed that the trial sets (VCP1 and VCS1) using ratio of paper mill waste: Cow dung: Straw (5:4:1) were effective in maintaining physiochemical parameters and different population attributes of earthworm. The present study had also demonstrated the enzymatic enrichment of vermicompost in terms of 19 enzymes such as α-Glucosidase, lipase, leucine aminopeptidase etc. in maintenance of C/N ratio of the compost. A significant reduction of heavy metals were noticed in vermicomposting of primary waste (VCP1) as Zn (40%) ​> ​Pb (36%) ​> ​Cr (28%) ​> ​Cu (25%) and secondary waste (VCS1) as Zn (44%) ​> ​Pb (41%) ​> ​Cu (19%) ​> ​Cr (13%). Such reduction of heavy metal was highly correlated with the reduction of C/N ratio of the vermicompost. The process of bioremediation was further manifested through the regular monitoring of bioaccumulation factor (BAF) among earthworm population in vermicomposting of primary waste (VCP1) as Zn (0.40) ​> ​Cu (0.23) ​> ​Cr (0.18) ​> ​Pb (0.11) and secondary waste (VCS1) as Zn (0.47) ​> ​Cu (0.25) ​> ​Cr (0.21) ​> ​Pb (0.14). Therefore, the study concludes that the ratio of paper mill waste, cow dung and straw (5:4:1) can be an efficient formulation in qualitative enrichment of different toxic organic paper mill wastes through vermicomposting

Plastic waste management during and post Covid19 pandemic: Challenges and strategies towards circular economy

Global petroleum consumption suffered drastically as lockdowns were put in place to contain the Coronavirus Disease 2019 (COVID-19). As a result, oil costs dropped, making virgin plastics more cost-effective than recycled plastics. The usage of plastic has increased as a result of lifestyle modifications, cost-based incentives, and other factors, further obscuring the issue. The utilization of personal protective equipment (PPE) during the pandemic had resulted in a significant surge in the quantity of plastic waste. The plastic packaging industry achieved a revenue milestone of US$ 909.2 billion in 2021, boosting a compound annual growth rate of 5.5 %. The escalating dependence on plastics imposed additional pressure on waste management systems, which were proven to be ineffective and insufficient in addressing the issue. This situation exacerbated the problem and contributed to environmental pollution. Globally, 40 % of plastic waste ended up in landfills, 25 % was incinerated, 16 % was recycled, and the remaining 19 % infiltrated within the environment. By investing in circular technologies like feedstock recycling and enhancing infrastructural and environmental conditions, it expected to become viable to manage plastic waste flows during such a period of crisis. Investing in valorization strategies that transform plastic waste into value-added goods, such as fuels and building materials, receives a compelling macroeconomic signal when both plastic waste and plastic demand are on the rise. A robust circular economy can be accomplished by finalising the life cycle of plastic waste. The concept of Plastic Waste Footprint (PWF) aims to assess the environmental impact of plastic products throughout their intended usage period. In the midst of the emerging challenges in waste management during and post pandemic period, this research study has been conducted to explore the challenges and strategies associated with plastic waste in the environment

Development of structures under the influence of heterogeneous flow field around rigid inclusions: insights from theoretical and numerical models

Rocks that are mechanically heterogeneous due to the presence of stiff or rigid inclusions floating in a ductile matrix, commonly show a variety of micro- to macro-scale structures developing under the influence of heterogeneous flow field in the neighbourhood of the inclusions. It is of fundamental importance to apprehend the nature of strain heterogeneity around inclusions to understand progressive development of structures associated with rigid inclusions such as strain shadow, foliation drag, porphyroclast mantle, porphyroblast inclusion trails, intragranular fractures, etc. The development of these diverse types of structures can be analyzed with the help of a suitable hydrodynamic theory. In this paper, we review different continuum models that have been proposed to characterize the heterogeneous flow field around rigid inclusions, focusing on recent developments. Recent studies reveal that Jeffery's [Proc. R. Soc. Lond. A 120 (1922) 161.] theory dealing with the motion of ellipsoidal rigid bodies in an infinitely extended viscous medium is more general in nature, and applicable for modeling the heterogeneous flow around both equant and inequant shapes of inclusions and ideal or non-ideal shear deformation of the matrix. The application of this theory, therefore, has advantages over other models, based on Lamb's [Lamb, H., 1932. Hydrodynamics. Cambridge University Press, Cambridge.] theory dealing with spherical inclusions. The review finally illustrates numerical simulations based on hydrodynamic theories, highlighting the controls of physical and kinematic factors on the progressive development of the structures mentioned above

Boudinage in multilayered rocks under layer-normal compression: a theoretical analysis

This paper presents a dynamic analysis of boudinage in multilayers of alternate brittle and ductile layers under layer-normal compression. Based on the mode of fracturing of individual brittle layers, boudinage is classified into three types: tensile fracture boudinage (Type 1), shear fracture boudinage (Type 2a) and extensional shear fracture boudinage (Type 2b). The layer-thickness ratio, Tr (=tb/td), and the strength ratio, F (=T/2ηε), between the brittle and the ductile units are the principal physical factors determining the type of boudinage. Type 1 boudinage develops rectangular boudins and occurs when Tr is low (<4.5) or F is high (>0.8). In contrast, Type 2a boudinage takes place when Tr is high (>8.5) or F is low (<0.5). The intermediate values of these factors delimit the field of extensional shear fracture boudinage. The square of fracture spacing or boudin width in Type 1 boudinage is linearly proportional to layer-thickness, whereas that in Type 2 boudinage shows a non-linear relationship with layer-thickness. The aspect ratio (Ar) of all the types of boudins is inversely proportional to layer-thickness ratio (Tr). However, Type 1 and Type 2 boudins, have contrasting aspect ratios, which are generally greater and less than 1, respectively

An analysis of anisotropy of rocks containing shape fabrics of rigid inclusions

This paper presents a theoretical basis for estimation of mechanical anisotropy in homogeneous rocks containing shape fabrics of rigid inclusions. The analysis is based on two types of viscous models: one containing linear fabrics of prolate (a > b = c) inclusions (cf. L-tectonite) and the other containing planar fabrics of oblate (a < b = c) inclusions (cf. S-tectonite). Models show contrasting bulk viscosities in stretching (normal viscosity) and shearing (shear viscosity) parallel to the fabric. The axial ratio R (= a/b) and the volume concentration (ρv) of rigid inclusions appear to be the principal parameters in determining the viscosity contrast. In anisotropic models with linear fabrics, normal viscosity (ηp) increases monotonically with increase in R, whereas shear viscosity (ηs) increases to a maximum, and then drops down to a near-stationary value. In anisotropic models with planar fabrics, the normal viscosity increases little with increasing flatness of inclusions, but the variation assumes a steep gradient when the latter is large. Shear viscosity, on the other hand, is relatively less sensitive to the shape of inclusions. The ratio of normal and shear viscosities, conventionally described as anisotropy factor δ, in both the models is always greater than 1, indicating that normal viscosity will be essentially greater than shear viscosity, irrespective of the axial ratio of inclusions forming the fabric. Models with a linear fabric show contrasting normal viscosities in pure shear flow along and across the linear fabric. The anisotropy is expressed by the ratio of longitudinal and transverse normal viscosities (anisotropic factor σ). It is revealed that the transverse viscosity is essentially less than the longitudinal viscosity, as observed in test models

Flow and strain patterns at the terminations of tapered shear zones

With the help of corner flow theory, this paper numerically analyzes the deformation pattern at the terminations of tapered shear zones, the walls of which are rigid and move parallel to each other in opposite directions. The overall flow pattern is characterized by curvilinear particle paths that show convexity towards and opposite to the tapering direction respectively for low (< 5°) and high (> 10°) inclinations of the wall verging opposite to the sense of wall movement. In tapered shear zones there are two distinct fields of instantaneous shortening and extension parallel to the direction of wall movement. Numerical models reveal that the finite strain distributions are generally asymmetrical with larger strain concentration occurring near the wall verging opposite to sense of wall movement. The S-foliation trajectories show a curvilinear pattern, convexing against the tapering direction. The analysis of rotationality (vorticity) indicates that the sense of vorticity near the synthetically verging wall is reverse to the sense of wall movement; however Wk is one everywhere within the shear zone