6,252 research outputs found
A capacity scaling algorithm for the constrained maximum flow problem
No full textIncludes bibliographical references (p. 19-20).Supported by the Air Force Office of Scientific Research. AFORS-88-0088 Supported by grants from UPS and Prime Computer Corporation.Ravindra K. Ahuja, I.I.T. Kanpur and James B. Orlin
On the optimal design of metal matrix composites as functionally graded innovative materials for sensor devices
No full textIn the present work an effort has been made to prepare Al matrix composite by 3D printing assisted rapid investment casting (RIC). The RIC has been performed by using patterns prepared by fused deposition modelling (FDM). For preparation of 3D parts, a composite material reinforced with ceramic particles (SiC and Al2O3) has been used as filament wire. The main motive of this research work is to prepare metal matrix composites as functionally graded innovative materials (FGIM), via investment casting as functional prototypes which will have wear resistance properties of SiC and Al2O3 (especially in rapid tooling (RT) applications. The reinforcements in the RT (as functional prototype) have been ensured by SEM analysis. The potential of the analysed materials for the fabrication of novel sensor devices is highlighted. Also the functional prototypes were checked for process capability analysis for batch production
Three Worlds of Cleaning: Women's Experiences of Precarious Labor in the Public Sector, Cleaning Companies and Private Households of West Germany, 1973-1998
No full textShould the low-pay and low-skill sector of the labor market be expanded through political intervention? This question is hotly debated in presentday Germany. In the cleaning trade, precarious employment is especially widespread, with precariousness defined as the undermining of material and legal standards as well as the exclusion from the solidarity of colleagues and from institutional forms of articulating interest in works council and trade union. This article discusses the transfer of cleaners’ jobs from the public sector to cleaning companies and private households since 1973. Drawing upon rare and scattered evidence contained in official statistics as well as upon journals of employers’ associations and of trade unions, the author argues that cleaners experienced increasing precariousness in each of these organizational arrangements, but especially when affected by the process of “double privatization.” For those who discuss future labor market strategies, the history of professional cleaning is of interest because it is paradigmatic for the whole low-skill service sector in many respects
Waste management by recycling of polymers with reinforcement of metal powder
No full textRecycling of plastics/polymers is one of the waste management techniques which have been followed by many researchers. In past 20 years large number of applications in this field has been highlighted. But hither to very few have reported on plastic waste management by recycling of polymers with reinforcement of metal powder. In the present work an effort has been made to perform recycling of waste plastic/polymer with reinforcement of metal powder by controlling the melt flow index (MFI). The present study of recycling of waste plastic has been performed on single screw extruder machine by considering various input parameters (namely: barrel temperature, die temperature, and screw speed/rpm). Investigations were performed for the parametric optimization of single screw extruder machine for different mechanical/metallurgical properties (like: porosity, peak elongation, break strength, Shore D hardness) with the help of case study of recycled high density polyethylene (HDPE)100%, HDPE90%+ Fe10%, low density polyethylene (LDPE)100% and LDPE94+6% (by wt.). As HDPE and LDPE do not decompose naturally, this nature makes these polymers suitable for structural applications (like in beams and reinforced concrete cements (RCC) structures)
Effect of single particle size, double particle size and triple particle size Al2O3 in Nylon-6 matrix on mechanical properties of feed stock filament for FDM
No full textFused Deposition modelling (FDM) is one of the additive manufacturing (AM) technologies used extensively for modelling and prototyping applications. In commercial FDM setup, filament wire is uncoiled from wire spools and plastic based material is supplied to produce the part. The application area of FDM is limited presently due to selective material availability in market. Some researchers have highlighted the use of reinforced composite wires as FDM filament. But hitherto no work has been reported on the effect of Single particle size (SPS), Dual particle size (DPS), Triple particle size (TPS) of Al2O3 (as reinforcement) in Nylon-6 matrix to be used as feed stock filament for FDM. In this paper, effect of SPS, DPS, and TPS of Al2O3 (as reinforcement) in Nylon-6 matrix on mechanical properties (like: percent age elongation, tensile strength, yield strength, Young’s modulus) has been studied. Further, empirical relations have been developed for above mentioned properties and a surface characteristic of developed wires has been observed with SEM image
On the design and preparation of metal matrix composites as functionally graded innovative materials
No full textProtein tyrosine phosphatases: structure, signaling and drug discovery/ Lalima G. Ahuja.
No full textIncludes bibliographical references and index.Protein tyrosine phosphatases remove phosphates from the phosphotyrosine residues of target proteins and reverse the action of various protein tyrosine kinases. This essential interplay between the opposing actions of protein tyrosine phosphatases and protein tyrosine kinases forms the basis of signaling networks that underlie the cellular workings of human physiology. Initially passed-off as housekeeping genes; these proteins were only acknowledged to maintain a steady background of phosphotyrosine levels in the cell. However, recent progress in studying their role in embryonic development and human disease has established their importance as regulators of signal regulation. Convincing evidence shows the role of mutations in these proteins to cause and/or intensify the severity of various diseases including metabolic and neurological disorders and also cancer. Protein tyrosine phosphatases have slowly, yet convincingly become crucial targets for therapeutic intervention of various human pathophysiologies. This book describes these signaling enzymes using the molecular details of their structure and mechanistic function. Various subtypes of cysteine-based Class I, II, III and the Haloacid dehalogenase related Class IV protein tyrosine phosphatases have been illustrated and explained. The superfamily of proteins is also described vis-a-vis its complimentary protein phosphoserine/phosphoserine phosphatases. Membrane bound receptor forms and the cytosolic non-receptor protein tyrosine phosphatases have been described for their biological function. This book serves as a reference for any reader looking to understand the sequence features, structural elements, molecular mechanism and cellular function of this superfamily of signaling enzymes.Frontmatter -- Preface -- About The Author -- Contents -- 1.Tyrosine Phosphorylation In Cell Signaling: Discovery And Beyond -- 2.Protein Phosphatases: Classification And Domain Architecture -- 3.Protein Tyrosine Phosphatases: Molecular Structure And Mechanism -- 4.The Receptor Protein Tyrosine Phosphatases: Structure And Function -- 5.The Double-Domain Receptor Protein Tyrosine Phosphatases -- 6 The Non-Receptor Protein Tyrosine Phosphatases: Part I -- 7.The Non-Receptor Protein Tyrosine Phosphatases: Part Ii -- 8.Protein Tyrosine Phosphatases: Strategies For Drug Development -- Index1 online resource (xiv, 282 pages
Scope and Space for small scale poultry production in developing countries
No full textIn recent years there has been growing recognition among the development community of the role of small scale commercial poultry production in accelerating the pace of poverty reduction and reaching out to the poorest of the poor. There is also growing evidence to demonstrate the role of small scale poultry in enhancing the food and nutrition security of the poorest households and in the promotion of gender equality. At the same time, the market and production context of poultry production has been changing rapidly over the last two decades. Rapid economic growth and urbanization in developing countries has resulted in fast expansion of industrial large scale, vertically integrated, poultry production units, specially in Asia. Opportunities have also expanded for small scale poultry enterprises due to improved market access infrastructure and a preference structure that might still favour free range birds and eggs. As a result, there has been increased market orientation even among small scale poultry enterprises. These changes have brought large and small production systems in overlapping competitive space which has created both challenges and opportunities. These changes have raised concerns about the sustainability of small scale poultry production systems due to (i) intensified competition from large scale producers who can exercise significant control over the poultry value chain (including concentrated holding of genetic stock of industrial poultry by a few multinational corporations), and (ii) the public perception that small units of production may be dangerous reservoirs of diseases, specially in the wake of recent outbreaks of HPAI. In the light of that background, this paper attempts to summarize the nature of small scale poultry production across nations and brings together some evidence on the viability of small scale poultry production in the wake of expanding large scale production systems with substantial economies of scale, well organized and integrated supply chains and the ability to respond to various types of risks. The paper argues that the main challenge for small-scale/rural poultry is organizational, not technical. Based on a review of available evidence, the paper concludes that it is important to continue to promote village poultry to contribute towards household nutrition security and livelihood support but concerted efforts must be made to find organizational solutions to minimize public health risks and provide appropriate extension support on issues like disease prevention, predation, improving hatchability, etc. Unfortunately most government extension programs in the developing countries are not oriented towards addressing the needs of poor households. While some private sector organizations (such as Kegg Farm in India) have invested significantly towards developing fast growing and more productive birds without requiring significant additional inputs, and have also made sufficient investment for developing the distribution network for birds, extension and public health support systems continue to be the weak point, making them vulnerable to exogenous shocks. This requires a well orchestrated public policy response in support of small scale poultry production.
Metal matrix composite from recycled materials by using additive manufacturing assisted investment casting
No full textIn this research article, a novel method of additive manufacturing (AM) assisted investment casting (IC) has been demonstrated (by using the patterns prepared from waste materials reinforced with ceramic particles) for development of a metal matrix composite (MMC). In first stage, recycled low density polyethylene (LDPE) has been selected as matrix material, while ceramic reinforcement of SiC and Al2O3 has been blended in LDPE by screw extrusion. Initially, the recycled LDPE has been collected in granules form from the local market and processed on single screw extruder to prepare pallets. The ceramic particles and LDPE were blended together to prepared the final blend in different proportions on twin screw extruder. After that Taguchi L9 orthogonal array has been employed to ascertain the affect of different input parameters of FDM machine to prepare the functional prototypes in the form of cubical patterns. Instead of using conventional IC, a rapid method has been employed to prepare sacrificial pattern by using siladent powder (which is being used for preparing cast in clinical dentistry for dentures). Further this method has been explored as an alternate route of rapid IC, which requires very less time as compared to the traditional methods. At final stage cast were prepared with aluminium (Al) alloy as matrix material reinforced with SiC and Al2O3 (which were present in the mould cavity after removal of LDPE). The properties of MMC prepared via this novel route were subjected to hardness and grain size testing supported by photomicrographs and EDAX analysis
Supplemental Material - Agricultural-waste <i>Sesamum indicum L.</i>/recycled-low density polyethylene bio-composites: Impact of gamma radiation on mechanical and thermal properties
No full textSupplemental Material for Agricultural-waste Sesamum indicum L./recycled-low density polyethylene bio-composites: Impact of gamma radiation on mechanical and thermal properties by Neha Bansal, Simran Ahuja, Sohan Lal, and Sanjiv Arora in Journal of Reinforced Plastics and Composites</p
- …
