312 research outputs found
Characterization of TLB and page allocation behavior on modern processors
No full textVirtual memory support is prevalent in most modern processors and is facilitated through Translation Lookaside Buffers (TLBs) which play a major role in the overall system performance. TLB misses are costly since they require multiple high latency memory references to walk the page table and locate the desired Virtual Page Number (VPN) - Physical Page Number (PPN) mapping. This study improves TLB hit rates by taking advantage of any contiguity present in the pages allocated by the Operating System (OS). By contiguity we refer to cases where consecutive VPNs are mapped to consecutive PPNs. Traditionally, OSs use large or superpages to collapse hundreds of such contiguous entries, thereby using one TLB entry to represent them rather than hundreds of entries they would normally require. Unfortunately due to implementation complexities superpaging has not been universally successful in reducing TLB pressure. We show, however, that even without explicit superpaging, various OS virtual memory allocation activities lead to intermediate levels of contiguity that may be exploited to coalesce TLB entries and significantly improve hit rates. We verify the presence of contiguity by running benchmarks on a real system and checking the page allocations of the OS. The OS page allocation schemes depend on memory pressure and memory defragmentation daemons. Further, we find an average contiguity of 30 pages over all the benchmarks and configurations with superpaging turned on and about 10 with superpaging turned off. To verify the performance of a Coalesced TLB we have implemented a fully associative TLB with variable size and Least Recently Used (LRU) replacement policy. Our results show an average hit rate improvement of 25% by adding an 8-16 entry fully associative Coalesced TLB. The Coalesced TLB further needs no complex hardware to implement, hence providing to a low cost means to reduce miss rates.M.S.Includes bibliographical referencesby Viswanathan Vaidyanatha
Sustainable product and market development for subsistence marketplaces: Creating educational initiatives in radically different contexts
No full textDeveloping products and business processes to serve subsistence marketplaces (or the roughly 4 billion poor around the world referred to as the bottom of the pyramid) is a significant challenge for businesses. Despite the importance of subsistence marketplaces, most product development educational curricula have been focused on relatively resource-rich and literate consumers and markets. We teach an innovative year-long product development course which includes an international immersion experience and which covers a broad spectrum of learning from understanding poverty, to consumer behavior, to product development and engineering design specifically for subsistence consumers. This unique course represents a pioneering effort to focus attention and create knowledge about product development, marketing, management, and engineering practices for subsistence marketplaces. Our two-semester course sequence for graduate-level students in a variety of business and engineering disciplines and industrial design combines in-class pedagogy with experiential learning and results in useful and marketable product concepts and prototypes. Working on projects with multinational companies or startups, students identify an opportunity of general need, conduct field market research to better understand subsistence consumer needs and contexts through an international immersion experience, develop a product concept, convert the concept to a workable prototype, and develop a manufacturing plan, marketing strategy, and overall business plan for the product. Overlaying the content found in a typical new product development lab course we develop a contextual understanding of subsistence marketplaces, setting the stage for new product development. A central aspect of the learning experience is travel to subsistence markets for actual immersion in the context and to conduct market research. Our course is at the confluence of two of the most important issues facing humanity, subsistence and sustainability. Lessons learned here can also be extended to other radically different contexts, such as future scenarios involving severe energy shortages or climate change consequences. Such educational initiatives provide challenging learning experiences in preparing students for the unique demands of the 21st century. © 2011 Product Development and Management Association.APPLE LE, 1988, J PROD INNOVAT MANAG, V5, P70, DOI 10.1111-1540-5885.510070; ASHBY M, 2003, MATER TODAY, V6, P24, DOI 10.1016-S1369-7021(03)01223-9; Cardozo RN, 2002, J PROD INNOVAT MANAG, V19, P4, DOI 10.1016-S0737-6782(01)00116-3; CHICK A, 1997, J SUSTAINABLE PRODUC, V1, P53; Donaldson KM, 2006, RES ENG DES, V17, P135, DOI 10.1007-s00163-006-0017-3; Ehrenreich B., 2002, NICKEL DIMED; Eppinger S.D., 2002, DESIGN MANAGEMENT J, V13, P58; GESCHKA H, 1986, J PROD INNOVAT MANAG, V3, P48, DOI 10.1016-0737-6782(86)90043-3; GREEN M, 2006, P ASME DES ENG TECHN; HAMMOND A. L., 2007, INNOVATIONS, V2, P147, DOI [10.1162-itgg.2007.2.1-2.147, DOI 10.1162-ITGG.2007.2.1-2.147]; HANNUKAINEN P, 2006, P ASME DES ENG TECHN; Hargadon A, 2000, HARVARD BUS REV, V78, P157; HAUSER JR, 1988, HARVARD BUS REV, V66, P63; HERSTATT C, 1992, J PROD INNOVAT MANAG, V9, P213, DOI 10.1016-0737-6782(92)90031-7; HORAN J, 2004, ONE PAGE BUSINESS PL; Murcott S., 2007, J INT DEV, V19, P123, DOI 10.1002-jid.1353; Prahalad CK, 2002, HARVARD BUS REV, V80, P48; PRAHALAD CK, 2005, FORT BOTT PYR ER POV; PUGH P, 1991, TOTAL DESIGN INTEGRA; Rodriguez J, 2006, INTERACT COMPUT, V18, P956, DOI 10.1016-j.intcom.2006.05.007; Sahlman WA, 1997, HARVARD BUS REV, V75, P98; Schumacher Ernest F., 1973, SMALL IS BEAUTIFUL E; *SME, 2003, PLAST INJ MOLD; *SME, 2004, FUND MAN PROC SAMPL; Sridharan S, 2008, J CONSUM MARK, V25, P455, DOI 10.1108-07363760810915671; Stone R. B., 2000, Design Studies, V21, DOI 10.1016-S0142-694X(99)00003-4; TAGUCHI J, 1990, HARVARD BUS REV, V68, P65; Tybout JR, 2000, J ECON LIT, V38, P11, DOI 10.1257-jel.38.1.11; Ulrich K., 2007, PRODUCT DESIGN DEV; Viswanathan M, 2005, J MARKETING, V69, P15, DOI 10.1509-jmkg.69.1.15.55507; Viswanathan M., 2009, IVEY BUSINESS J MAR; Viswanathan M, 2009, J MACROMARKETING, V29, P406, DOI 10.1177-0276146709345620; Viswanathan M, 2008, EDUC ASIA PAC REG-IS, V12, P1, DOI 10.1007-978-1-4020-5769-4; Viswanathan M., 2007, PRODUCT MARKET DEV S, P1; Viswanathan M., 2007, PRODUCT MARKET DEV S, P212
Outside the fold conversion, modernity, and belief
No full text"Outside the Fold is a radical reexamination of religious conversion. Gauri Viswanathan skillfully argues that conversion is an interpretive act that belongs in the realm of cultural criticism. To that end, this work examines key moments in colonial and postcolonial history to show how conversion questions the limitations of secular ideologies, particularly the discourse of rights central to both the British empire and the British nation-state. Implicit in such questioning is an attempt to construct an alternative epistemological and ethical foundation of national community. Viswanathan grounds her study in an examination of two stimultaneous and, she asserts, linked events: the legal emancipation of religious minorities in England and the acculturation of colonial subjects to British rule. The author views these two apparently disparate events as part of a common pattern of national consolidation that produced the English state. She seeks to explain why resistance, in both cases, frequently took the form of religious conversion, especially to "minority" or alternative religions. Confronting the general characterization of conversion as assimilative and annihilating of identity, Viswanathan demonstrates that a willful change of religion can be seen instead as an act of opposition. Outside the Fold concludes that, as a form of cultural crossing, conversion comes to represent a vital release into difference.""Through the figure of the convert, Viswanathan addresses the vexing question of the role of belief and minority discourse in modern society. She establishes new points of contact between the convert as religious dissenter and as colonial subject. This convergence provides a transcultural perspective not otherwise visible in literary and historical texts. It allows for radically new readings of significant figures as diverse as John Henry Newman, Pandita Ramabai, Annie Besant, and B. R. Ambedkar, as well as close studies of court cases, census reports, and popular English fiction. These varying texts illuminate the means by which discourses of religious identity are produced, contained, or opposed by the languages of law, reason, and classificatory knowledge. Outside the Fold is a challenging, provocative contribution to the multidisciplinary field of cultural studies. Book jacket."--BOOK JACKE
The secondary substrate problem in Co-Evolution and Developmental-Evolution
No full textThe performance of an Evolutionary Algorithm on a search problem is critically effected by the substrate used to encode the candidate solutions of the problem. In addition to the challenge of designing evolvable genetic substrates, two-population competitive coevolutionary algorithms (coEAs) and developmental Evolutionary Algorithms(devo-EAs) present another substrate-related design problem. Both involve an additional substrate with its own mechanism of change. In coEAs, test-cases are encoded with an independent genetic substrate having its own variation operators. In devo-EAs, phenotypes are composed of a distinct substrate with associated generative mechanisms capable of changing an individual's form and size during development. Though this "secondary" substrate is a distinctive feature of both algorithms, the design problem it poses remains poorly understood. This dissertation proposes novel formal models to characterize how the properties of the secondary substrate influences the performance devo-EAs and coEAs respectively.
Firstly, we propose a computational model for devo-EAs which shows that the point in time at which the development of a phenotype halts can introduce selection biases that can cause an empirically measurable retardation in the performance of a devo-EA. Furthermore, a Genotype-Phenotype map that is bias-free is formally equivalent to a Nash equilibrium in a non-cooperative multi-player game, where each genotype is a player, the possible halting points are strategies and the payoffs are related to the fitness function. We show that algorithmic solutions to find this Nash map are expensive without a suitable secondary substrate.
Secondly, we propose a novel search space model for Pareto coevolution that formally defines the evolvability properties required of the secondary substrate for pathology-free learning with a mutation-only coEA.With this model, we show that on boolean classification problems (a) the variational properties of the secondary substrate are a property of the problem class rather than tied to individual problems, and (b) the absence of coevolutionary pathologies does not imply success in finding high-quality solutions. Rather than being mysterious dynamical properties of coEAs, these findings are transparently explained using Machine Learning first principles
How artificial ontogenies can retard evolution
No full textRecently there has been much interest in the role of indirect genetic encodings as a means to achieve increased evolvability. From this perspective, artificial ontogenies have largely been seen as a vehicle to relate the indirect encodings to complex phenotypes. However, the introduction of a development phase does not come without other consequences. We show that the conjunction of the latent ontogenic stucture and the common practice of only evaluating the final phenotype obtained from development can have a net retarding effect on evolution. Using a formal model of development, we show that this effect arises primarily due to the relation between the ontogenic structure to the fitness function, which in turn impacts the properties being evaluated and selected for during evolution. This effect is empirically demonstrated with a toy search problem using LOGO-turtle based embryogenic processes
REANALYSIS OF THE EMISSION SPECTRUM OF IN FOREIGN GASES
No full textA. L. Guy, K.S. Viswanathan, A. Sur, and J. Tellinghuisen, Chem. Phys. Lett. 73, 582 (1980). H. Hemmati and G. J. Collins, Chem. Phys. Lett. 67, 5 (1979). P. Venkateswarlu, Phys. Rev. 81. 821 (1951). R. D. Verma, Proc. Ind. Acad. Sci. 48A, 197 (1958). K.S. Viswanathan, A. Sur, and J. Tellinghuisen, J. Mol. Spectrosc. (in press).Author Institution:The emission spectrum of in foreign gases is studied as a function of pressure, temperature, end isotopic species, using a tesla discharge as Evidence is found for at least 12 of the 18 ion-pair states arising from , of which (2g) appears to be the lowest. The pressure- and temperature-dependent spectra support the suggestion that both the 3400-A system and a broad band near 5000 A originate from this state. High-resolution spectra show discrete structure in electronic bands at 2380 A, 2770 A, and 2880 A, in addition to the well-known F-X (2700 A), D-A(3400 A), and E-B (4300 A) systems. The 2380 system originates from a state near and terminates on the X state near v = 50. The 2770 system, which was previously as terminating on the X or B state, is now found to involve the A() The 2880 system terminates on a weakly bound lower slate which probably dissociates to ground-stale atoms. Work is continuing on the other electronic bands of the emission spectrum, most of which appear to be diffuse
Product Configuration Optimization For Disassembly Planning: A Differential Approach
No full textProduct configuration immensely influences the suitability of a product for end-of-life (EOL) disassembly. The product configuration is the relative spatial and logical arrangement of the different parts/sub-assemblies of the product with respect to each other. The complexity involved in studying the influence of configuration design on EOL disassembly has limited the scope of the current design for disassembly (DfD) approaches to guideline-based prescriptive methods and index-based evaluation techniques. The application of these approaches has primarily been limited to specific case studies of product redesign. Many of the current methods do not provide the necessary rigor that will lead to the creation of a theoretical base for addressing product configuration issues which is indispensable during product redesign. Though fraught with obstacles, studying the effects of product configuration on DfD will be useful to develop automated configuration optimization methods for EOL disassembly. To this end, a model to study the combinatorial configuration design optimization problem from a disassembly perspective is described in this study. The different structural principles of the design space derived in this study provide insights into the possibilities and the natural shortcomings of automated optimization of a product by relating the effects of design constraints and disassembly requirements on product redesign. A hierarchical evolutionary programming based algorithm is also developed to test the design solutions generated by the proposed model
Disassembly-Oriented Product Classification using Neural Networks
No full textThe increasing importance of a product\u27s relationship and effects on the environment has prompted active research in Environment Conscious Design and Manufacture (ECDM). Disassembly of a product makes a product\u27s parts available for recycling, remanufacturing or reuse. With the increasing complexity and variety of new products, the emergence of dedicated facilities to handle the enormity of this disassembly task in the near future is forseeable. Grouping diverse products based on their similarity in dissassembly characteristics would result in a more effective and flexible use of the capabilities of different disassembly factories. A modification of the growing neural gas network model was found to be effective to implement this grouping
Towards an Evolutionary-Developmental Approach for Real-World Substrates
No full textExtending "body-brain" evolution to the real-world presents a number of difficulties due to conflicting idealizations between evolutionary and constructional models. Toward addressing this gap, we develop a simple model system to analyze the effects of undoing these idealizations. Preliminary experiments with this system show that high variability developmental substrates can influence evolutionary dynamics by causing ambiguities in selection. Furthermore the substrate can enable the evolution of adaptive responses to nondeterministic developmental effects
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