385 research outputs found

    Periodic attractors of perturbed one-dimensional maps

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    In this paper we investigate how many periodic attractors maps in a small neighbourhood of a given map can have. For this purpose we develop new tools which help to make uniform cross-ratio distortion estimates in a neighbourhood of a map with degenerate critical points

    Cyclicity in families of circle maps

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    In this paper we will study families of circle maps of the form x↩x+2πr+af(x)(mod2π) and investigate how many periodic trajectories maps from this family can have for a ‘typical’ function f provided the parameter a is small

    Passive Wireless Saw Sensors With New And Novel Reflector Structures Design And Applications

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    Surface acoustic wave (SAW) devices are a solution for today’s ever growing need for passive wireless sensors. Orthogonal frequency coding (OFC) together with time division multiplexing (TDM) provides a large number of codes and coding algorithms producing devices that have excellent collision properties. Novel SAW noise-like re- flector (NLR) structures with pulse position modulation (PPM) are shown to exhibit good auto- and cross-correlation, and anti-collision properties. Multi-track, multi-transducer approaches yield devices with adjustable input impedances and enhanced collision properties for OFC TDM SAW sensor devices. Each track-transducer is designed for optimum performance for loss, coding, and chip reflectivity. Experimental results and theoretical predictions confirm a constant Q for SAW transducers for a given operational bandwidth, independent of device and transducer embodiment. Results on these new NLR SAW structures and devices along with a new novel 915 MHz transceiver based on a software radio approach was designed, built, and analyzed. Passive wireless SAW temperature sensors were interrogated and demodulated in a spread spectrum correlator system using a new adaptive filter. The first-ever SAW OFC four-sensor operation was demonstrated at a distance of 1 meter and a single sensor was shown to operate up to 3 meters. Comments on future work and directions are also presente

    Drivers of Success to Effective Entrepreneurship: A Comparison of Immigrant and Native-born Perceptions

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    The literature indicates that only a few studies have compared immigrant and non-immigrant entrepreneurs in the United States. The present study addresses this gap by inquiring how these populations perceive drivers of success. I employed an in-depth, multi-case analysis of immigrant and nonimmigrant entrepreneurs operating in the United States. Data were collected from semi-structured interviews. Adaptive comparative causal maps (CCMs), which are qualitative methodological tools, were used to illustrate similarities and differences between the groups. I identified 155 drivers of success. I ascertained connections, deviations, and causal linkages as well as portrayed overlaps and divergences in the groups’ perspectives regarding the perceptions of success drivers. There were many differences detected between the groups, such as immigrants’ views that being innovative and able to adapt to trends (entrepreneurial orientation (EO)), being dynamic (EO), and able to build a reliable team (business orientation (BO)) influence success. Nonimmigrants perceived that communicating with customers (BO) and the ability to calculate risks (EO) are the factors that affect success. Despite having many differences, both groups regarded BO drivers (e.g., leadership skills, market orientation, and financial capabilities) as the most influential determinants of success. Among EO drivers, the groups indicated that innovative capability exerts the most significant effect on success. This study contributes to research and practice through its determination of immigrant and nonimmigrant perceptions of EO and BO drivers and their effects on entrepreneurial success. The findings are expected to assist practitioners, scholars, and educators in formulating improved strategies and creating training programs for developing EO and BO factors and, consequently, clear the way for entrepreneurial success. This is the first qualitative study that utilized the research model that incorporated both EO and BO to observe the separate effects of these orientations on entrepreneurial success, the first study that compares immigrant and nonimmigrant perceptions of drivers of success, and the first in the business and entrepreneurship disciplines to employ and build on the CCM technique. Overall, the research adds to the existing body of knowledge by filling the gap in how the aforementioned method is used, wherein rules and regulations for standard dimensional gauges are lacking

    On the structure of isentropes of real polynomials

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    In this paper we will modify the Milnor--Thurston map, which maps a one dimensional mapping to a piece-wise linear of the same entropy, and study its properties. This will allow us to give a simple proof of monotonicity of topological entropy for real polynomials and better understand when a one dimensional map can and cannot be approximated by hyperbolic maps of the same entropy. In particular, we will find maps of particular combinatorics which cannot be approximated by hyperbolic maps of the same entropy

    Parity and the resolution of value conflicts in design

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    Recent developments in theories for responsible innovation have focused on the importance of actively accounting for values in our technological designs. Leading among these theories is that of Value Sensitive Design (VSD) which attempts to guide the design process on the basis of evaluative analysis. However, values often come into conflict and VSD has been criticized for not providing a proper method to resolve such inevitable conflicts. This paper examines three such methods and argues that although each has its merits, they all fail to account for a common source of value conflicts known as value incommensurability. Drawing on literature from the field of axiology, this paper argues that by incorporating the evaluative relation of ‘parity’ each of these three methods, and the VSD framework in general, will be able to properly understand the relation which holds between conflicting design options stemming from the incommensurable of values and be able to guide designers in making rational decision in the face of such conflicts

    Surface acoustic wave coding for orthogonal frequency coded devices

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    Methods and systems for coding SAW OFC devices to mitigate code collisions in a wireless multi-tag system. Each device producing plural stepped frequencies as an OFC signal with a chip offset delay to increase code diversity. A method for assigning a different OCF to each device includes using a matrix based on the number of OFCs needed and the number chips per code, populating each matrix cell with OFC chip, and assigning the codes from the matrix to the devices. The asynchronous passive multi-tag system includes plural surface acoustic wave devices each producing a different OFC signal having the same number of chips and including a chip offset time delay, an algorithm for assigning OFCs to each device, and a transceiver to transmit an interrogation signal and receive OFC signals in response with minimal code collisions during transmission

    Surface Acoustic Wave Device Coding for Multi-Device ID Tags and Sensors (CIP)

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    Methods and systems for coding SAW OFC devices to mitigate code collisions in a wireless multi-tag system. Each device producing plural stepped frequencies as an OFC signal with a chip offset delay to increase code diversity. A method for assigning a different OCF to each device includes using a matrix based on the number of OFCs needed and the number chips per code, populating each matrix cell with OFC chip, and assigning the codes from the matrix to the devices. The asynchronous passive multi-tag system includes plural surface acoustic wave devices each producing a different OFC signal having the same number of chips and including a chip offset time delay, an algorithm for assigning OFCs to each device, and a transceiver to transmit an interrogation signal and receive OFC signals in response with minimal code collisions during transmission
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