25,997 research outputs found
A QFD-Based Mathematical Model for New Product Development Considering the Target Market Segment
Responding to customer needs is important for business success. Quality function deployment provides systematic procedures for converting customer needs into technical requirements to ensure maximum customer satisfaction. The existing literature mainly focuses on the achievement of maximum customer satisfaction under a budgetary limit via mathematical models. The market goal of the new product for the target market segment is usually ignored. In this study, the proposed approach thus considers the target customer satisfaction degree for the target market segment in the model by formulating the overall customer satisfaction as a function of the quality level. In addition, the proposed approach emphasizes the cost-effectiveness concept in the design stage via the achievement of the target customer satisfaction degree using the minimal total cost. A numerical example is used to demonstrate the applicability of the proposed approach and its characteristics are discussed
Parity-time electromagnetic diodes in a two-dimensional nonreciprocal photonic crystal
We propose a kind of electromagnetic (EM) diode based on a two-dimensional nonreciprocal gyrotropic photonic crystal. This
periodic microstructure has separately broken symmetries in both parity
(P) and time-reversal (T) but obeys parity-time (PT) symmetry. This
kind of diode could support bulk one-way propagating modes either for
group velocity or phase velocity with various types of negative and
positive refraction. This symmetry-broken system could be a platform to
realize abnormal photoelectronic devices, and it may be analogous to an
electron counterpart with one-way features
One-way cloak based on nonreciprocal photonic crystal
We propose a physical concept of non-reciprocal transformation optics, by which a one-way invisible cloak is designed. The one-way invisible cloak is made of a coordinate-transformed nonreciprocal photonic crystal, showing a perfect cloaking for wave incident from one direction but acting as a perfect reflector for wave from the counter direction. The proposed design shows a high promise of applications in military, as protecting the own information to be detected but efficiently grabbing the information from the “enemy” side
Destabilizing the autoinhibitory conformation of Zap70 induces up-regulation of inhibitory receptors and T cell unresponsiveness.
Zap70 plays a critical role in normal T cell development and T cell function. However, little is known about how perturbation of allosteric autoinhibitory mechanisms in Zap70 impacts T cell biology. Here, we analyze mice with a hypermorphic Zap70 mutation, W131A, which destabilizes the autoinhibitory conformation of Zap70, rendering the kinase in a semiactive state. W131A mutant mice with wild-type T cell receptor (TCR) repertoires exhibited relatively normal T cell development. However, crossing the W131A mutant mice to OTII TCR transgenic mice resulted in increased negative selection of OTII+ thymocytes and in increased thymic and peripheral T regulatory cells. Strikingly, increased basal TCR signaling was associated with a marked increase in inhibitory receptor expression and with T cells that were relatively refractory to TCR stimulation. PD-1 inhibitory receptor blockade partially reversed T cell unresponsiveness. Collectively, disruption of normal Zap70 autoinhibition engaged negative feedback mechanisms by which negative selection and inhibitory receptors restrain TCR signaling to enforce both central and peripheral tolerance
Fabrication, characterization, and kinetic study of vertical single-crystalline CuO nanowires on Si substrates
We report here on the first study of the growth kinetics of high-yield, vertical CuO nanowires on silicon substrates produced by the process of thermal oxidation. The length of the CuO nanowires could be tuned from several to tens of micrometers by adjusting the oxidation temperature and time. The grown CuO nanowires were determined to be single-crystalline with different axial crystallographic orientations. After a series of scanning electron microscopy examinations, the average length of CuO nanowires produced at each temperature was found to follow a parabolic relationship with the oxidation time. The parabolic growth rate at different oxidation temperatures was measured. The activation energy for the growth of CuO nanowires calculated from an Arrhenius plot was found to be about 174.2 kJ/mole. In addition, the current-voltage characterization indicated that the sample with high-density CuO nanowires exhibited ohmic behavior, and its resistance was found to significantly decrease with increasing environmental temperature. The result can be attributed to an increase in the number of carriers at higher temperatures
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