Showing papers by "Delhi Technological University published in 2010"

Genetic algorithm for optimization of welding variables for height to width ratio and application of ANN for prediction of bead geometry for TIG welding process

Abstract: This paper explains an integrated method with a new approach using experimental design matrix of experimental designs technique on the experimental data available from conventional experimentation, application of neural network for predicting the weld bead geometric descriptors and use of genetic algorithm for optimization of process parameters. The properties of the welded joints are affected by a large number of welding parameters. Modeling of weld bead shape is important for predicting the quality of welds. In an attempt to model the welding process for predicting the bead shape parameters (also known as bead geometry parameters) of welded joints, modeling and optimization of bead shape parameters in tungsten inert gas (TIG) welding process has been tried in the present work. Multiple linear regression technique has been used to develop mathematical models for weld bead shape parameters of TIG welding process, considering the effects of main variables as well as two factor interactions. Also by using the same experimental data, an attempt has been made to predict the bead shape parameters using back-propagation neural network. To optimize the process parameters for the desired front height to front width ratio and back height to back width ratio, genetic algorithmic approach has been applied.

Lean manufacturing system for medium size manufacturing enterprises: an Indian case

Abstract: Competitive market is forcing big organizations to utilize the untapped potential of Medium Size Manufacturing Enterprises (MSME). In the era of outsourcing, MSMEs are the important links in the su...

Revisiting Flexibility in Organizations: Exploring its Impact on Performance

Abstract: Today’s knowledge age organizations operate in more turbulent business and regulatory environments and managers need to take proactive stance in creating combating strategies for such environments and to adapt to such external turbulent environments. Incorporation of ‘Flexibility’ in strategic processes of any organization becomes very important at various levels in all the perspectives of the organization. This paper critically highlights the gap in flexibility research that flexibility is not merely related to technology but flexibility is more deeply rooted in strategic management processes of organizations. The paper reviews the developments in different types of flexibility studies such as organizational, technical, operational, strategic, marketing and financial flexibility. The area of flexibility and organization strategy is emerging and needs a lot of attention in order to understand its impact on various management processes within organization leading to enhanced competitiveness and better performance. This paper also emphasizes on how flexibility has evolved as a concept and taken a shape of strategic driver to improve organizational performance.

Some Bianchi Type-V Models of Accelerating Universe with Dark Energy

Abstract: The paper deals with a spatially homogeneous and anisotropic universe filled with perfect fluid and dark energy components. The two sources are assumed to interact minimally together with a special law of variation for the average Hubble's parameter in order to solve the Einstein's field equations. The law yields two explicit forms of the scale factor governing the Bianchi-V space-time and constant values of deceleration parameter. The role of dark energy with variable equation of state parameter has been studied in detail in the evolution of Bianchi-V universe. It has been found that dark energy dominates the Universe at the present epoch, which is consistent with the observations. The Universe achieves flatness after the dominance of dark energy. The physical behavior of the Universe has been discussed in detail.

Empirical validation of object-oriented metrics for predicting fault proneness at different severity levels using support vector machines

Abstract: Empirical validation of software metrics to predict quality using machine learning methods is important to ensure their practical relevance in the software organizations It would also be interesting to know the relationship between object-oriented metrics and fault proneness at different severity levels In this paper, we build a Support vector machine (SVM) model to find the relationship between object-oriented metrics given by Chidamber and Kemerer and fault proneness, at different severity levels The proposed models at different severity levels are empirically evaluated using public domain NASA data set The performance of the SVM method was evaluated by receiver operating characteristic (ROC) analysis Based on these results, it is reasonable to claim that such models could help for planning and performing testing by focusing resources on fault-prone parts of the design and code The performance of the model predicted using high severity faults is low as compared to performance of the model predicted with respect to medium and low severity faults Thus, the study shows that SVM method may also be used in constructing software quality models However, similar types of studies are required to be carried out in order to establish the acceptability of the model

Performance and emission studies on an agriculture engine on neat Jatropha oil

Abstract: Diesel engines have proven their utility in the transportation, agriculture, and power sectors in India. They are also potential sources of decentralized energy generation for rural electrification. Concerns on the long-term availability of petroleum diesel and the stringent environmental norms have mandated the search for a renewable alternative to diesel fuel to address these problems. Vegetable oils have been considered good alternatives to diesel in the past couple of years. However, there are many issues related to the use of vegetable oils in diesel engine. Jatropha curcas has been promoted in India as a sustainable substitute to diesel fuel. This study aims to develop a dual fuel engine test rig for evaluating the potential suitability of Jatropha oil as diesel fuel and for determining the performance and emission characteristics of an engine with Jatropha oil. The experimental results suggest that engine performance using Jatropha oil is slightly inferior to that of diesel fuel. The thermal efficiency of the engine was lower, while the brake-specific fuel consumption was higher with Jatropha oil compared with diesel fuel. The levels of nitrogen oxides (NOx) from Jatropha oil during the entire duration of the experiment were lower than those of diesel fuel. The reduction of NOx was found to be an important characteristic of Jatropha oil as NOx emission is the most harmful gaseous emission from engines; as such, its reduction is always the goal of engine researchers and makers. During the entire experiment, carbon monoxide (CO), hydrocarbon (HC), and carbon dioxide (CO2) emissions in the case of using Jatropha oil were higher than when diesel fuel was used. The higher density and viscosity of Jatropha oil causes lower thermal efficiency and higher brakespecific fuel consumption. The performance and emission characteristics found in this study are significant for the study of replacing diesel fuel from fossils with Jatropha oil in rural India, where the availability of diesel has always been a problem.

Genetic-Algorithm-Based Design of Passive Filters for Offshore Applications

Abstract: With the proliferation of power electronics converters and increased use of magnetics, power lines have become highly polluted. Both passive and active filters have been used near harmonic-producing loads or at the point of common coupling to mitigate/block current harmonics. Shunt filters still dominate the harmonic compensation at medium/high voltage level, whereas active filters have been proclaimed for low/medium voltage ratings. With diverse applications involving reactive power together with harmonic compensation, passive filters are found suitable. For offshore platforms, having multiple variable frequency drives for oil exploration and the power fed through submerged power cable reduces the reactive power requirement in the power system. Under such reduced reactive power requirement, the design of passive filter conforming to the IEEE 1531 standard is presented in this paper. This paper utilizes genetic algorithm technique to design the tuned harmonic filters to compensate current harmonics together with limited reactive power compensation. The main idea behind the design is minimization of net source rms current with insertion of a passive filter. The formulation thus becomes a combinational optimization system with nondifferentiable objective function. Other environmental and operational constraints are also incorporated in the design technique to ensure their effective performance. The performance and operation of the so-designed passive filter has been studied through simulation under MATLAB environment.

Development of Novel Bio-Based Soybean Oil Epoxy Resins as a Function of Hardener Stoichiometry

Abstract: Bio-based epoxy materials were prepared from epoxidized soybean oil (ESO) with an anhydride-curing agent. Variation of anhydride/epoxy ratio (R) was found to have significant effect on the resulting properties of the materials. The properties were studied and compared by dynamic mechanical analysis (DMA), izod impact, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The glass transition temperature reaches the maximum at stoichiometric ratio related to the cross-link density of the formed networks. These materials are thermally stable but exhibit a rapid decrease as the anhydride/epoxy ratio was increased.

New grounded simulated inductance circuit using a single PFTFN

Abstract: A new single-PFTFN based lossless grounded inductance simulation circuit has been presented. The proposed circuit employs a single PFTFN along with four resistors and a single capacitor and realises a lossless grounded inductance subject to the fulfillment of only one realization condition. Some sample results of circuits realized with the new simulated inductor using existing CMOS FTFN implementation have been given to demonstrate the workability of the new circuit.

Lean manufacturing in biscuit manufacturing plant: a case

Abstract: Day by day the intensifying global competition is throwing challenges in the form of uncertainty and fluctuation in demand, necessity to provide wide variety to attract and hold the ever demanding customer. To survive and succeed under such competitive environment, organisations are forced to find and adopt efficient and effective ways for their operations. Organisations are seeking ways to increase the value of their products and services by eliminating unnecessary processes and practices from all systems. Lean manufacturing is a systematic team-based approach for finding and eliminating waste. The implementation of Lean manufacturing system helps organisations to reduce lead-time and inventory, improve quality, and achieve better on-time deliveries and utilisation of resources leading towards increased sales and profit through customer satisfaction. The Indian biscuit industry is the third largest manufacturer of biscuit in the world producing around 60% of the total production in organised sector and the balance 40% by the unorganised bakeries. In this paper, a medium sized biscuit manufacturing plant is studied under the framework of lean manufacturing system and observed that 5S, kaizen, quick changeover, TPM and TEI are some of the tools, which can be effectively used to improve equipment availability, reduce wastage of material and improve quality.

Host sensitized novel red phosphor CaZrSi2O7 : Eu3+ for near UV and blue LED-based white LEDs

Abstract: A series of red phosphors Ca1?xZrSi2O7?:?Eux (x = 0.5,1,5,10,12?mol%) were prepared by a solid-state reaction technique at various temperatures and their structural and optical properties were investigated. The x-ray diffraction profiles showed that all peaks could be attributed to the monoclinic phase CaZrSi2O7 doped with Eu3+. SEM, FTIR, TG and DTA profiles have also been characterized to explore their structural properties. The luminescence properties of these resulting phosphors have been characterized by photoluminescence spectra. The host matrix itself has shown a strong blue emission which has its maximum intensity at 470?nm. The excitation spectra of CaZrSi2O7?:?Eu3+ revealed two excitation bands at 395 and 464?nm which correspond to the sharp 7F0?5L6 and 7F0?5D2 transitions of Eu3+ and matches well with the two popular emissions from n-UV/blue GaN-based LEDs. The prominent red emission was obtained at 615?nm by the excitation transitions 5L6, 5D2 of Eu3+ through the non-radiative energy transfer process from the host to the Eu3+ ion. The effects of charge compensation by monovalent ions on the luminescence behaviour of a red emitting phosphor CaZrSi2O7?:?Eu3+ were investigated. The high colour saturation and the low thermal quenching effect of these phosphors make it a potential red component for white light emitting diodes (w-LEDs).

Scope for lean implementation: a survey of 127 Indian industries

Abstract: Lean manufacturing is a plethora of principles that focus on cost reduction by identifying and eliminating non-value added activities. Indian industry is still struggling to implement lean principles and philosophies. Through this paper, an attempt has been made to identify the scope for lean implementation in Indian industry which forces the Indian industry to adopt lean manufacturing initiatives. A questionnaire is prepared after identifying 26 issues of lean implementation with discussion to industrial personals and sent to 300 Indian industries. The responses of 127 industries were received on a five-point scale ranging from very low to very high. By applying factor analysis, 26 lean issues were reduced in to five broad categories, i.e., customers issues, organisational issues, supplier issues, market issues and top management issues. Further descriptive statistics was used to find the importance of lean issues to Indian industry.

Impact of information sharing on competitive strength of Indian manufacturing enterprises: An empirical study

Abstract: – The purpose of this paper is to find the effect of different types of information sharing on the competitive strengths of the Indian manufacturing enterprises., – The paper is based on the responses received from the Indian manufacturers to a questionnaire based survey. Statistical analysis has been done to identify the relationship with the type of information sharing and the competitive strengths of the manufacturing enterprises., – It is observed that information sharing has significant impact on the competitive strengths of the manufacturer in order winning parameters like cost effectiveness and service level., – The paper reflects Indian manufacturing perspective and only positive impacts of the information sharing has been discussed in the paper., – The paper verifies that the various types of information sharing can lead firms to acquire different competitive strengths. Managers should focus on right information sharing in their way to enhance particular competitive strength.

Power Conditioner for Variable-Frequency Drives in Offshore Oil Fields

Abstract: The proliferation of variable-frequency ac motor drives (VFDs) as submersible pumps in oil exploration has aggravated many power-quality problems on the distribution network, for which VFDs are themselves susceptible to maloperation. The distortion in the input voltage waveform is a major issue, since the offshore power system cannot be regarded as a stiff source, and thus, distortions in the voltage waveform become more severe, which disturbs other loads connected at the point of common coupling (PCC). The oil fields require the operation of many parallel-connected VFDs on the same bus. Such a system significantly increases the power-quality problems on the distribution network. In this paper, an active power conditioner which is connected in series between the source and the PCC, and its dc bus shared with one of the VFDs connected to the bus, is proposed to mitigate a majority of power-quality problems for the whole bus. The proposed single power conditioner is sufficient to block the harmonic currents flowing toward the source, balance the currents from the source side, protect the VFDs on the bus against sag/swell at PCC, protect preinstalled passive filters connected with VFDs against series and parallel resonances, and maintain regulated balanced voltages at PCC. Investigations are carried out to validate the use of the proposed topology of a power conditioner to safeguard the distribution system and a set of VFDs against major power-quality problems. The proposed power conditioner employs a new control scheme based on an indirect current control for its effective operation under varying load conditions on different VFDs connected to the same bus.

External Electric Field Effects on Optical Property and Excitation Dynamics of Capped CdS Quantum Dots Embedded in a Polymer Film

Abstract: Nanocomposites of benzyl mercaptan (BM)-capped cadmium sulfide (CdS) quantum dots (QDs) have been prepared and investigated by using electric field modulation spectroscopy. Applied electric fields on absorption and photoluminescence (PL) spectra as well as PL decays of BM-capped CdS QDs embedded in a poly(methyl methacrylate) (PMMA) film have revealed a field-induced alteration. Electro-photoluminescence (E-PL) exhibits field-induced quenching of photoluminescence in the presence of electric fields. The observed E-PL spectra and field-induced change in decay profile suggest that the PL intensity alternation originates from the electric field effect on emitting state population rather than PL quantum yield, probably as a result of the presence of field-assisted dissociation into hole and electron at the photoexcited state having a charge-separated character. Field-induced change in absorption spectra showed the spectral broadening caused by the stark shifts, indicating a large electric dipole moment in the...

Impedance spectroscopy analysis of Ba5NdTi3Nb7O30 ferroelectric ceramic

Abstract: The polycrystalline sample of Ba5NdTi3Nb7O30, a member of tungsten bronze family, was prepared by solid-state reaction method. X-ray diffraction (XRD) analysis shows the formation of single-phase compound with an orthorhombic structure. Scanning electron micrograph of the material shows uniform grain distribution throughout the sample. Variation of dielectric constant (e′r) with temperature at different frequencies shows that the compound has a dielectric anomaly of ferroelectric to paraelectric type at 100 °C, and exhibits non-relaxor kind of diffuse phase transition. Studies of electrical properties of Ba5NdTi3Nb7O30 using the complex impedance spectroscopy (CIS) technique show the decrease in bulk resistance with rise in temperature indicating a typical negative temperature coefficient of resistance (NTCR)-type behaviour. A possible hopping mechanism for electrical transport in the system is evident from the modulus analysis.

Strength and dilatancy of jointed rocks with granular fill

Abstract: It is well recognised that the strength of rock masses depends upon the strain history, extent of discontinuities, orientation of plane of weakness, condition of joints, fill material in closely packed joints and extent of confinement. Several solutions are available for strength of jointed rock mass with a set of discontinuities. There is a great multiplicity in the proposed relationships for the strength of jointed rocks. In the present study, the author conceives the effect of increasing stresses to induce permanent strains. This permanent strain appears as micro crack, macro crack and fracture. A fully developed network of permanent deformations forms joint. The joint may contain deposits of hydraulic and hydrothermal origin commonly known as gouge. The joint factor numerically captures varied engineering possibilities of joints in a rock mass. The joints grow as an effect of loading. The growth of the joints is progressive in nature. It increases the joint factor, which modifies the failure stresses. The dilatancy explains the progressive failure of granular media. Hence, a mutual relationship conjoins effectively the strength of jointed rock and a dilatancy-dependent parameter known as relative dilatancy. This study provides a simple and integral solution for strength of jointed rocks, interpreted in relation to the commonly used soil, and rock parameters, used for a realistic design of structure on rock masses. It has scope for prediction of an equivalent strength for tri-axial and plane strain conditions for unconfined and confined rock masses using a simple technique.

Development of Polyaniline/Epoxy Composite as a Prospective Solder Replacement Material

Abstract: In this paper we present a novel application of a conducting polymer, polyaniline, as a conductive filler for the development of isotropically conductive adhesives. We have developed isotropically conductive adhesives using protonic acid-doped polyaniline as the conducting filler in an anhydride-cured epoxy system. Fundamental material characterization like DSC, TGA and SEM of the samples was conducted to study their properties. Conductivity of these materials was measured by the four probe method while impact properties were studied by lap shear and drop tests. Samples were aged at 85°C/∼100% RH for more than 500 h and the effects of aging were studied. Conductivity value of 10−3 S/cm was obtained at 25% PANI filler concentration. These results demonstrate the potential of such systems to function as isotropically conductive adhesives.

Interpretive structural modelling for selection of best supply chain practices

Abstract: Supply chain management (SCM) is one of the most important areas that have recently generated a great deal of interest in both industry and academia. The supply chain (SC) is a linked set of resources and processes that begins with the sourcing of raw materials and extends through to the delivery of end items to the final customer. This study has tried to review some of the SC practices and identified factors responsible for selecting best SCM practices. Structural relationship has been developed by interpretive structural modelling among these factors. This model is further illustrated with a case study.

Investigations of Structural, Dielectric and Electrical Behaviour of Calcium Substituted Ba5NdTi3Nb7O30 Ferroelectric Ceramics

Abstract: In the present work, the effect of partial substitution of barium by calcium in Ba5NdTi3Nb7O30 has been investigated. The samples were synthesized by solid state reaction method and studied for their structural, dielectric, conductivity and ferroelectric properties. The X-ray diffractograms confirm the formation of single phase orthorhombic tungsten-bronze structure. Detailed dielectric properties of the compounds as a function of frequency and temperature show that the compounds undergo non-relaxor type ferroelectric-paraelectric phase transition of diffuse nature. An increase in Curie temperature (Tc ) from 100°C to 140°C is observed on the substitution of calcium. The Polarization–Electric field (P-E) studies show that the remanent polarization (2Pr ) increases on the substitution of calcium in Ba5NdTi3Nb7O30. The temperature dependence of dc-conductivity shows that the conductivity increases with increase in temperature revealing the negative temperature coefficient of resistance (NTCR) behaviour of t...

Interpretive structural modelling of enablers for improving the performance of automobile service centre

Abstract: The current growth of the service sector in global economies is unparalleled in human history. Even large manufacturing firms are seeing dramatic shifts in percent revenue derived from services. The growing dynamism of the automotive sector, the enlargement of markets, the changes in the strategic position of suppliers, the introduction of new rules and the diffusion of the internet have great impact on manufacturer's after sales configuration. Considering the complexities in Automobile Service Centre (ASC), a model is developed for the variables affecting the performance of ASC and studies the interrelationship among the variables. Interpretive Structural Modelling (ISM) is used as tool for the present study and structural relationship model has been developed. Driving elements are also found using MICMAC analysis. The present research provides innovative business models for product service system design. The study will help the managers of ASC in developing the policies for improvement in performance of ASC.

A novel OTRA based oscillator with non interactive control

Abstract: An Operational Transresistance amplifier (OTRA) based sinusoidal oscillator is proposed. This oscillator circuit provides independent control on frequency and condition of oscillation. The oscillator circuit is insensitive to parasitic input capacitances due to internally grounded terminals of OTRA. PSPICE simulations have been given to verify the theoretical analysis.

Characterization of Biodegradable Packaging Films Derived from Potato Starch and LDPE Grafted with Maleic Anhydride–LDPE Composition. Part-II

Abstract: LDPE has been mixed with LDPE-g-mA (LDPE grafted with (0.5%) maleic anhydride) in 1:1 ratio containing a polar group in the LDPE backbone. Blown film samples containing various percentages of Potato Starch 0, 2.5, 5.0, 7.5, 10.0, 12.5 and 15% and LDPE grafted with maleic anhydride/LDPE (1:1), have been prepared using extrusion film blowing under temperature profile ranging from 120 to 160 °C. Characteristics of prepared packaging films up to 15% Potato Starch were analysed for their mechanical properties (Tensile strength, Elongation at break, Bursting strength and Tear strength), water absorption properties and morphology. The compatibility of the system with the introduction of 50% LDPE grafted with maleic anhydride with various ratios of starch, have been verified with the help of resulting datasets. The resulting datasets were placed in theoretical models of Willet modifies Kerner’s equation and Nicolais and Narkis models. Procedure adopted above could make thermally stable, highly flexible, crystalline resultant material, which can be adopted as an alternative of LDPE material especially for packaging applications.