41,401 research outputs found

    Fluid valve assembly

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    A valve assembly is reported for controlling the flow of fluids between the inlet and outlet of a fluid valve. The valve assembly contains a barrier element which is porous for providing fluid communication between the valve inlet and outlet. The valve assembly also includes a sealing element that is movable relative to the barrier element between a first position, in which fluid flow through the porous portion of the barrier element is blocked preventing fluid communication between the valve inlet and outlet, and a second position, in which the porous portion is unblocked, permitting fluid communication between the valve inlet and outlet

    Modification of physical properties of freeze-dried rice

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    Freeze cycling process consists of alternately freezing and thawing precooked rice for two cycles, rice is then frozen and freeze-dehydrated in vacuum sufficient to remove water from rice by sublimitation. Process modifies rice grain structure and porosity, enabling complete rehydration in one minute in hot water

    Suppression of the Charge-Density-Wave State in Sr10_{10}Ca4_{4}Cu24_{24}O41_{41} by External Pressure

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    The influence of external pressure on the charge-density-wave (CDW) ground state of the quasi-one-dimensional two-leg ladder compound Sr10_{10}Ca4_{4}Cu24_{24}O41_{41} has been studied by optical reflectivity measurements as a function of temperature (10 - 300~K) and pressure PP (0.3 - 4.3~GPa) over the spectral range 580 - 6000 cm1^1. With increasing pressure the CDW transition temperature TCDWT_{CDW} decreases with the linear pressure coefficient \approx-70~K/GPa, and above \approx3~GPa the CDW phase is suppressed at all temperatures. This behavior is similar to that in compounds Sr14x_{14-x}Cax_xCu24_{24}O41_{41} with increasing Ca content xx at ambient pressure, with the simple scaling x3P(GPa)x \approx 3\cdot P(GPa). The size of the CDW gap decreases with increasing pressure, whereas the dimensionality of the high-temperature insulating phase in Sr10_{10}Ca4_{4}Cu24_{24}O41_{41} within the ladder plane is hardly affected by external pressure.Comment: accepted for publication in Phys. Rev.

    Composite parameterization and Haar measure for all unitary and special unitary groups

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    We adopt the concept of the composite parameterization of the unitary group U(d) to the special unitary group SU(d). Furthermore, we also consider the Haar measure in terms of the introduced parameters. We show that the well-defined structure of the parameterization leads to a concise formula for the normalized Haar measure on U(d) and SU(d). With regard to possible applications of our results, we consider the computation of high-order integrals over unitary groups.Comment: 28 pages, example and references added, accepted by J. Math. Phy

    A composite parameterization of unitary groups, density matrices and subspaces

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    Unitary transformations and density matrices are central objects in quantum physics and various tasks require to introduce them in a parameterized form. In the present article we present a parameterization of the unitary group U(d)\mathcal{U}(d) of arbitrary dimension dd which is constructed in a composite way. We show explicitly how any element of U(d)\mathcal{U}(d) can be composed of matrix exponential functions of generalized anti-symmetric σ\sigma-matrices and one-dimensional projectors. The specific form makes it considerably easy to identify and discard redundant parameters in several cases. In this way, redundancy-free density matrices of arbitrary rank kk can be formulated. Our construction can also be used to derive an orthonormal basis of any kk-dimensional subspaces of Cd\mathbb{C}^d with the minimal number of parameters. As an example it will be shown that this feature leads to a significant reduction of parameters in the case of investigating distillability of quantum states via lower bounds of an entanglement measure (the mm-concurrence).Comment: 13 pages, 1 figur

    Preservation of flavor in freeze dried green beans

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    Before freeze drying, green beans are heated to point at which their cell structure is altered. Beans freeze dried with altered cell structure have improved rehydration properties and retain color, flavor, and texture
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