103,131 research outputs found

    MEMS flow sensors for nano-fluidic applications

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    This paper presents micromachined thermal sensors for measuring liquid flow rates in the nanoliter-per-minute range. The sensors use a boron-doped polysilicon thinfilm heater that is embedded in the silicon nitride wall of a microchannel. The boron doping is chosen to increase the heater’s temperature coefficient of resistance within tolerable noise limits, and the microchannel is suspended from the substrate to improve thermal isolation. The sensors have demonstrated a flow rate resolution below 10 nL/min, as well as the capability for detecting micro bubbles in the liquid. Heat transfer simulation has also been performed to explain the sensor operation and yielded good agreement with experimental data

    Arithmetic Properties of Overpartition Pairs

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    Bringmann and Lovejoy introduced a rank for overpartition pairs and investigated its role in congruence properties of ppˉ(n)\bar{pp}(n), the number of overpartition pairs of n. In particular, they applied the theory of Klein forms to show that there exist many Ramanujan-type congruences for the number ppˉ(n)\bar{pp}(n). In this paper, we shall derive two Ramanujan-type identities and some explicit congruences for ppˉ(n)\bar{pp}(n). Moreover, we find three ranks as combinatorial interpretations of the fact that ppˉ(n)\bar{pp}(n) is divisible by three for any n. We also construct infinite families of congruences for ppˉ(n)\bar{pp}(n) modulo 3, 5, and 9.Comment: 19 page

    Software-Engineering Process Simulation (SEPS) model

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    The Software Engineering Process Simulation (SEPS) model is described which was developed at JPL. SEPS is a dynamic simulation model of the software project development process. It uses the feedback principles of system dynamics to simulate the dynamic interactions among various software life cycle development activities and management decision making processes. The model is designed to be a planning tool to examine tradeoffs of cost, schedule, and functionality, and to test the implications of different managerial policies on a project's outcome. Furthermore, SEPS will enable software managers to gain a better understanding of the dynamics of software project development and perform postmodern assessments
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