Showing papers by "Georgia Institute of Technology published in 1994"
TL;DR: The formation of organizations that are international from inception is an increasingly important phenomenon that is incongruent with traditionally expected characteristics of multinational enterprises as mentioned in this paper, and a framework is presented that explains the phenomenon by integrating international business, entrepreneurship, and strategic management theory that describes four necessary and sufficient elements for the existence of international new ventures.
Abstract: The formation of organizations that are international from inception—international new ventures—is an increasingly important phenomenon that is incongruent with traditionally expected characteristics of multinational enterprises A framework is presented that explains the phenomenon by integrating international business, entrepreneurship, and strategic management theory That framework describes four necessary and sufficient elements for the existence of international new ventures: (1) organizational formation through internalization of some transactions, (2) strong reliance on alternative governance structures to access resources, (3) establishment of foreign location advantages, and (4) control over unique resources
3,469 citations
TL;DR: In this article, the authors study the formation process of International New Venture (INV) and find that the formation of an INV is not explained by existing theories from the field of international business.
1,696 citations
TL;DR: Enhanced preservation is observed in low-O2 and euxinic environments, and aspects of the biochemistries of the aerobic and anaerobic process are reviewed, and a new model for organic carbon decomposition, the "pseudo-G" model, is developed.
836 citations
TL;DR: In a spontaneously bursting neuronal network in vitro, chaos can be demonstrated by the presence of unstable fixed-point behaviour, and chaos control techniques can increase the periodicity of such neuronal population bursting behaviour.
Abstract: In a spontaneously bursting neuronal network in vitro, chaos can be demonstrated by the presence of unstable fixed-point behaviour. Chaos control techniques can increase the periodicity of such neuronal population bursting behaviour. Periodic pacing is also effective in entraining such systems, although in a qualitatively different fashion. Using a strategy of anticontrol such systems can be made less periodic. These techniques may be applicable to in vivo epileptic foci.
791 citations
TL;DR: It is suggested that speed of processing should be viewed as a fundamental part of the architecture of the cognitive system as it develops across the entire lifespan.
766 citations
TL;DR: In this paper, the advantages of plotting a.c. data in terms of impedance, electric modulus, and dissipation factor simultaneously are illustrated, and the degree to which these assignments may be made is related to the dielectric relaxation ratio ( r = ϵ s ϵ ∞ ) and the differences between the time constants of the different relaxation processes present in the material being examined.
746 citations
02 Oct 1994
TL;DR: In this article, the authors used motor current spectral analysis to detect rolling-element bearing damage in induction machines, where the bearing failure modes were reviewed and bearing frequencies associated with the physical construction of the bearings were defined.
Abstract: This paper addresses the application of motor current spectral analysis for the detection of rolling-element bearing damage in induction machines. Vibration monitoring of mechanical bearing frequencies is currently used to detect the presence of a fault condition. Since these mechanical vibrations are associated with variations in the physical air gap of the machine, the air gap flux density is modulated and stator currents are generated at predictable frequencies related to the electrical supply and vibrational frequencies. This paper takes the initial step of investigating the efficacy of current monitoring for bearing fault detection by correlating the relationship between vibration and current frequencies caused by incipient bearing failures. The bearing failure modes are reviewed and the characteristic bearing frequencies associated with the physical construction of the bearings are defined. The effects on the stator current spectrum are described and the related frequencies determined. This is an important result in the formulation of a fault detection scheme that monitors the stator currents. Experimental results which show the vibration and current spectra of an induction machine with different bearing faults are used to verify the relationship between the vibrational and current frequencies. The test results clearly illustrate that the stator current signature can be used to identify the presence of a bearing fault. >
703 citations
TL;DR: This article conducted exploratory studies and mental model interviews to characterize public understanding of climate change and found that respondents regarded global warming as both bad and highly likely, and they tended to confuse stratospheric ozone depletion with the greenhouse effect and weather with climate.
Abstract: A set of exploratory studies and mental model interviews was conducted in order to characterize public understanding of climate change. In general, respondents regarded global warming as both bad and highly likely. Many believed that warming has already occurred. They tended to confuse stratospheric ozone depletion with the greenhouse effect and weather with climate. Automobile use, heat and emissions from industrial processes, aerosol spray cans, and pollution in general were frequently perceived as primary causes of global warming. Additionally, the [open quotes]greenhouse effect[close quotes] was often interpreted literally as the cause of a hot and steamy climate. The effects attributed to climate change often included increased skin cancer and changed agricultural yields. The mitigation and control strategies proposed by interviewees typically focused on general pollution control, with few specific links to carbon dioxide and energy use. Respondents appeared to be relatively unfamiliar with such regulatory developments as the ban on CFCs for nonessential uses. These beliefs must be considered by those designing risk communications or presenting climate-related policies to the public. 20 refs., 4 tabs.
646 citations
TL;DR: The theoretical development of a direct adaptive tracking control architecture using neural networks based on feedback linearization of the aircraft dynamics is presented and a stable weights adjustment rule for the on-line neural network is derived.
Abstract: The theoretical developmentofa direct adaptivetracking controlarchitectureusingneuralnetworks ispresented. Emphasis is placed on utilization of neural networks in a ight control architecture based on feedback linearization of the aircraft dynamics. Neural networks are used to represent the nonlinear inverse transformation needed for feedback linearization. Neural networks may be rst trained off line using a nominalmathematicalmodel, which provides an approximate inversion that can accommodate the total ight envelope. Neural networks capable of on-line learning are required to compensate for inversion error, which may arise from imperfect modeling, approximate inversion, or sudden changes in aircraft dynamics. A stable weights adjustment rule for the on-line neural network is derived. Under mild assumptions on the nonlinearities representing the inversion error, the adaptation algorithm ensures that all of the signals in the loop are uniformly bounded and that the weights of the on-line neural network tend to constant values. Simulation results for an F-18 aircraft model are presented to illustrate the performance of the on-line neural network based adaptation algorithm.
616 citations
Book•
29 Jul 1994TL;DR: In this paper, the authors introduce center manifolds, normal forms, and two bifurcations with codimension higher than two Bibliography index, and show that the center manifold can be decomposed into center and normal forms.
Abstract: Preface 1. Center manifolds 2. Normal forms 3. Codimension one bifurcations 4. Codimension two bifurcations 5. Bifurcations with codimension higher that two Bibliography Index.
554 citations
TL;DR: The authors use a case study to describe the model's conversation metaphor, which follows analysis activities from requirements elicitation and documentation through refinement, and at its core is the inquiry cycle model.
Abstract: This approach emphasizes pinpointing where and when information needs occur; at its core is the inquiry cycle model, a structure for describing and supporting discussions about system requirements. The authors use a case study to describe the model's conversation metaphor, which follows analysis activities from requirements elicitation and documentation through refinement. >
TL;DR: High growth industry environments were found to provide a favorable environment for new ventures to achieve sales growth; however, the highest sales growth rates were exhibited by new ventures pursuing broad breadth strategies in high growth industries.
Abstract: A sample of 123 independent new ventures was classified into four industry growthlstrategic breadth categories. High growth industry environments were found to provide a favorable environment for new ventures to achieve sales growth; however, the highest sales growth rates were exhibited by new ventures pursuing broad breadth strategies in high growth industries. One-way ANOVA and contrast tests were also used to identify whether specific strategic variables varied across the four industry growth/strategic breadth combinations. New ventures in high growth industries chose to enter on a larger, more aggressive scale and placed more emphasis on new product development than those entering low growth industries. Broad breadth strategy ventures had higher levels of advertising and promotion expenses and placed greater emphasis on the dominance of marketing expertise in their top management team, developing new channels of distribution, and on brand name recognition. Ventures pursuing focus strategies emphasized specialty products and were less cost conscious.
TL;DR: A much better bound is proved on the tree-width of planar graphs with no minor isomorphic to a g × g grid and this is the best known bound.
TL;DR: Following a decade of explosive attention to climate change in politics and in the mainstream media, survey respondents in 2009 showed higher awareness and comprehension of some climate change causes, and many individuals in 2009 still had incorrect beliefs about climate change, and still did not appear to fully appreciate key facts.
Abstract: In 1992, a mental-models-based survey in Pittsburgh, Pennsylvania, revealed that educated laypeople often conflated global climate change and stratospheric ozone depletion, and appeared relatively unaware of the role of anthropogenic carbon dioxide emissions in global warming. This study compares those survey results with 2009 data from a sample of similarly well-educated laypeople responding to the same survey instrument. Not surprisingly, following a decade of explosive attention to climate change in politics and in the mainstream media, survey respondents in 2009 showed higher awareness and comprehension of some climate change causes. Most notably, unlike those in 1992, 2009 respondents rarely mentioned ozone depletion as a cause of global warming. They were also far more likely to correctly volunteer energy use as a major cause of climate change; many in 2009 also cited natural processes and historical climatic cycles as key causes. When asked how to address the problem of climate change, while respondents in 1992 were unable to differentiate between general "good environmental practices" and actions specific to addressing climate change, respondents in 2009 have begun to appreciate the differences. Despite this, many individuals in 2009 still had incorrect beliefs about climate change, and still did not appear to fully appreciate key facts such as that global warming is primarily due to increased concentrations of carbon dioxide in the atmosphere, and the single most important source of this carbon dioxide is the combustion of fossil fuels.
TL;DR: Three regions of the northern mid-latitudes, the continental-scale metro-agro-plexes, presently dominate global industrial and agricultural productivity, and it is estimated that about 10 to 35 percent of the world's grain production may occur in parts of these regions where ozone pollution may reduce crop yields.
Abstract: Three regions of the northern mid-latitudes, the continental-scale metro-agro-plexes, presently dominate global industrial and agricultural productivity. Although these regions cover only 23 percent of the Earth's continents, they account for most of the world's commercial energy consumption, fertilizer use, food-crop production, and food exports. They also account for more than half of the world's atmospheric nitrogen oxide (NOx,) emissions and, as a result, are prone to ground-level ozone (O(3)) pollution during the summer months. On the basis of a global simulation of atmospheric reactive nitrogen compounds, it is estimated that about 10 to 35 percent of the world's grain production may occur in parts of these regions where ozone pollution may reduce crop yields. Exposure to yield-reducing ozone pollution may triple by 2025 if rising anthropogenic NOx emissions are not abated.
TL;DR: Testing the hypothesis that flowfield properties are closely related to the localization of plaques in this segment of the arterial system demonstrates that in the infrarenal aorta, regions of low mean and oscillating wall shear stresses are predisposed to the development of plaque while regions of relatively high wallShear stress tend to be spared.
TL;DR: Perceived environment, perceived incentive and outcome, and person constructs for relationships with interest and participation in voluntary learning and development activity by nonmanagement employees showed the need to carefully consider individual differences in this context when targeting many different types of employees for participation.
Abstract: The authors examined perceived environment, perceived incentive and outcome, and person constructs for relationships with interest and participation in voluntary learning and development activity by nonmanagement employees. All 3 groups of constructs were related to development activity. In relationships with development activity, perceived outcome and environment variables interacted with workers' personal values relevant to aspects of a development setting, illustrating the potentially important role that differences in values may play in a development setting, illustrating the potentially important role that differences in values may play in a development context. Additionally, small relationships were observed between several demographic variables and values within a development setting. Results provide implications for the design and implementation of successful development programs and highlight the need to carefully consider individual differences in this context when targeting many different types of employees for participation.
TL;DR: The author defines symmetric convolution, relates the DSTs and DCTs to symmetric-periodic sequences, and then uses these principles to develop simple but powerful convolution-multiplication properties for the entire family of DST sine and cosine transforms.
Abstract: This paper discusses the use of symmetric convolution and the discrete sine and cosine transforms (DSTs and DCTs) for general digital signal processing. The operation of symmetric convolution is a formalized approach to convolving symmetrically extended sequences. The result is the same as that obtained by taking an inverse discrete trigonometric transform (DTT) of the product of the forward DTTs of those two sequences. There are 16 members in the family of DTTs. Each provides a representation for a corresponding distinct type of symmetric-periodic sequence. The author defines symmetric convolution, relates the DSTs and DCTs to symmetric-periodic sequences, and then use these principles to develop simple but powerful convolution-multiplication properties for the entire family of DSTs and DCTs. Symmetric convolution can be used for discrete linear filtering when the filter is symmetric or antisymmetric. The filtering will be efficient because fast algorithms exist for all versions of the DTTs. Conventional linear convolution is possible if one first zero-pad the input data. Symmetric convolution and its fast implementation using DTTs are now an alternative to circular convolution and the DFT. >
TL;DR: It follows that branch-width is polynomially computable for planar graphs—that too is NP-hard for general graphs.
Abstract: Suppose we expect there to bep(ab) phone calls between locationsa andb, all choices ofa, b from some setL of locations. We wish to design a network to optimally handle these calls. More precisely, a “routing tree” is a treeT with set of leavesL, in which every other vertex has valency 3. It has “congestion” 0 form the edges of a planar graphG, there is an efficient, strongly polynomial algorithm. This is because the problem is equivalent to deciding if a ratcatcher can corner a rat loose in the walls of a house with floor planG, wherep(ab) is a thickness of the wallab. The ratcatcher carries a noisemaker of powerk, and the rat will not move through any wall in which the noise level is too high (determined by the total thickness of the intervening walls between this one and the noisemaker). It follows that branch-width is polynomially computable for planar graphs—that too is NP-hard for general graphs.
TL;DR: A new realization of stochastic resonance is described, applicable to a broad class of systems, based on an underlying excitable dynamics with deterministic reinjection of sensory neurons in the crayfish.
Abstract: We describe a new realization of stochastic resonance, applicable to a broad class of systems, based on an underlying excitable dynamics with deterministic reinjection. A simple but general theory of such ``single-trigger'' systems is compared with analog simulations of the Fitzhugh-Nagumo model, as well as experimental data obtained from stimulated sensory neurons in the crayfish.
Book•
01 Feb 1994TL;DR: The observation of synchronization of the chaotic intensity fluctuations of two Nd:YAG lasers when one or both the lasers are driven chaotic by periodic modulation of their pump beams is reported.
Abstract: We report the observation of synchronization of the chaotic intensity fluctuations of two Nd:YAG lasers when one or both the lasers are driven chaotic by periodic modulation of their pump beams.
TL;DR: In this paper, the authors prove several sharp inequalities specifying uniform convexity and uniform smoothness properties of the Schatten trace ideals C p, which are the analogs of the Lebesgue spaces L p in noncommutative integration.
Abstract: We prove several sharp inequalities specifying the uniform convexity and uniform smoothness properties of the Schatten trace ideals C p, which are the analogs of the Lebesgue spaces L p in non-commutative integration. The inequalities are all precise analogs of results which had been known in L p, but were only known in C p for special values of p. In the course of our treatment of uniform convexity and smoothness inequalities for C p we obtain new and simple proofs of the known inequalities for L p.
TL;DR: In this article, the authors apply the path-dependent model to examine health policy reform in Germany, France, Great Britain and the United States, and develop the interplay of structure with conjuncture, the occasional accomplishment of big change - in spite of path dependency - can be systematically understood.
Abstract: The idea of path-dependency is applied to an examination of health policy reform in Germany, France, Great Britain and the United States. In the path-dependent model, actors are hemmed in by existing institutions and structures that channel them along established policy paths. Therefore, in any system, big (non-incremental) change is unlikely. However, sometimes we do observe big change. Why? By developing the interplay of structure with conjuncture, the occasional accomplishment of big change - in spite of path dependency - can be systematically understood.
TL;DR: Sediment studies indicate that most sedimentary pyrite is formed rapidly from iron oxides, with smaller amounts formed more slowly from iron silicates (if sufficient geologic time is available), so it is recommended that the degree of pyritisation be defined with respect to the dithionite-extractable pool and/or the boiling HCl-extracted pool for the recognition of iron-limited pyritification.
TL;DR: In this paper, the dominant nonmethane organic species present in the atmosphere sampled primarily over eastern Canada (0-6 km, 35 deg-65 deg N) during ABLE3B (July to August 1990) was measured.
Abstract: Acetone (CH3COCH3) was found to be the dominant nonmethane organic species present in the atmosphere sampled primarily over eastern Canada (0-6 km, 35 deg-65 deg N) during ABLE3B (July to August 1990). A concentration range of 357 to 2310 ppt (= 10(exp -12) v/v) with a mean value of 1140 +/- 413 ppt was measured. Under extremely clean conditions, generally involving Arctic flows, lowest (background) mixing ratios of 550 +/- 100 ppt were present in much of the troposphere studied. Correlations between atmospheric mixing ratios of acetone and select species such as C2H2, CO, C3H8, C2Cl4 and isoprene provided important clues to its possible sources and to the causes of its atmospheric variability. Biomass burning as a source of acetone has been identified for the first time. By using atmospheric data and three-dimensional photochemical models, a global acetone source of 40-60 Tg (= 10(exp 12) g)/yr is estimated to be present. Secondary formation from the atmospheric oxidation of precursor hydrocarbons (principally propane, isobutane, and isobutene) provides the single largest source (51%). The remainder is attributable to biomass burning (26%), direct biogenic emissions (21%), and primary anthropogenic emissions (3%). Atmospheric removal of acetone is estimated to be due to photolysis (64%), reaction with OH radicals (24%), and deposition (12%). Model calculations also suggest that acetone photolysis contributed significantly to PAN formation (100-200 ppt) in the middle and upper troposphere of the sampled region and may be important globally. While the source-sink equation appears to be roughly balanced, much more atmospheric and source data, especially from the southern hemisphere, are needed to reliably quantify the atmospheric budget of acetone.
02 Oct 1994
TL;DR: In this article, a new method for online induction motor fault detection is presented, which utilizes artificial neural networks to learn the spectral characteristics of a good motor operating online, which may contain many harmonics due to the load which correspond to normal operating conditions.
Abstract: A new method for online induction motor fault detection is presented in this paper. This system utilizes artificial neural networks to learn the spectral characteristics of a good motor operating online. This learned spectrum may contain many harmonics due to the load which correspond to normal operating conditions. In order to reduce the number of harmonics which are continuously monitored to a manageable number, a selective frequency filter is employed. This frequency filter only passes those harmonics which are known to be of importance in fault detection, or which are continuously above a set level, to a neural net clustering algorithm. After a sufficient training period, the neural network signals a potential failure condition when a new cluster is formed and persists for some time. Since a fault condition is found by comparison to a prior condition of the machine, online failure prediction is possible with this system without requiring information on the motor or load characteristics. The detection algorithm was implemented and its performance verified on various fault types.
TL;DR: Emile implements software‐realized scaffolding to facilitate student learning of physics by facilitating students building computer‐based models and simulations and an evaluation of Emile's effectiveness is presented.
Abstract: Programming is an activity through which students can learn about other domains, but the difficulty of programming diminishes its usefulness as a learning activity. One approach to facilitate the use of programming for learning is to view programming as a skill like those taught through apprenticeships, and to use the apprenticeship concept of scaffolding to facilitate doing and learning through programming. Scaffolding means providing modifiable support (through fading) that communicates process, coaches, and elicits articulation. Software‐realized scaffolding embeds scaffolding in a computer‐based environment. Emile implements software‐realized scaffolding to facilitate student learning of physics by facilitating students building computer‐based models and simulations. In this article, I present Emile's features as examples of software‐realized scaffolding, and I present the results of an evaluation of Emile's effectiveness. Students were able to use Emile to create fairly sophisticated program...
TL;DR: It is shown that cultural differences in trust do influence perceptions of transaction costs and the preference for direct foreign investment across countries.
Abstract: This paper argues that national differences in levels of trust impact perceptions of transactions costs and thereby influence the desirability of internalization and the choice of foreign market entry mode. The paper tests this framework on industry level data from the United States Commerce Department's Benchmark Survey of operations of U. S. -based manufacturing multinational corporations in 1977 and 1982, and shows that cultural differences in trust do influence perceptions of transaction costs and the preference for direct foreign investment across countries.