Flow Regulation of Cryogenic Fluids : Design of a High-Rangeability Control Valve

To control the mass fl ow, the pressure or the temperature in a cryogenic plant, often cryogenic control valves are used. These valves regulate thanks to the axial movement of a throttling element with defi ned geometry, controlled by a pneumatic actuator and an electro-pneumatic positioner. The electro-pneumatic positioner in combination with a pneumatic actuator drives the valve to the position where the needed opening is being realized. The smoother the relationship of the opening vs. the stroke of the valve is, the more precise the positioner can accomplish its task. In particular in the case, when the same valve should be able to operate in several working points (for example cool down, warm up and cold operation) or with different loads of the plant, the opening vs. stroke curve becomes challenging. It demands to cover a high range of regulation values (high rangeability). In extreme cases, the plant may have a smaller valve for the control of low mass fl ows in parallel to a larger valve, because the needed “rangeability” cannot be reached in only one valve. This contribution shows how a high “rangeability” can be reached in order to cover multiple functions with the same valve and shows the comparison of the calculated values with Kv measurements

Experimental validation of a self-calibrating cryogenic mass flowmeter

The Karlsruhe Institute of Technology (KIT) and the WEKA AG jointly develop a commercial flowmeter for application in helium cryostats. The flowmeter functions according to a new thermal measurement principle that eliminates all systematic uncertainties and enables self-calibration during real operation. Ideally, the resulting uncertainty of the measured flow rate is only dependent on signal noises, which are typically very small with regard to the measured value. Under real operating conditions, cryoplant-dependent flow rate fluctuations induce an additional uncertainty, which follows from the sensitivity of the method. This paper presents experimental results with helium at temperatures between 30 and 70 K and flow rates in the range of 4 to 12 g/s. The experiments were carried out in a control cryostat of the 2 kW helium refrigerator of the TOSKA test facility at KIT. Inside the cryostat, the new flowmeter was installed in series with a Venturi tube that was used for reference measurements. The measurement results demonstrate the self-calibration capability during real cryoplant operation. The influences of temperature and flow rate fluctuations on the self-calibration uncertainty are discussed

Global public policy, transnational policy communities, and their networks

Public policy has been a prisoner of the word "state." Yet, the state is reconfigured by globalization. Through "global public–private partnerships" and "transnational executive networks," new forms of authority are emerging through global and regional policy processes that coexist alongside nation-state policy processes. Accordingly, this article asks what is "global public policy"? The first part of the article identifies new public spaces where global policies occur. These spaces are multiple in character and variety and will be collectively referred to as the "global agora." The second section adapts the conventional policy cycle heuristic by conceptually stretching it to the global and regional levels to reveal the higher degree of pluralization of actors and multiple-authority structures than is the case at national levels. The third section asks: who is involved in the delivery of global public policy? The focus is on transnational policy communities. The global agora is a public space of policymaking and administration, although it is one where authority is more diffuse, decision making is dispersed and sovereignty muddled. Trapped by methodological nationalism and an intellectual agoraphobia of globalization, public policy scholars have yet to examine fully global policy processes and new managerial modes of transnational public administration

Alkaline-earth phosphonate MOFs with reversible hydration-dependent fluorescence

A new rigid tritopic phosphonic ligand, 2,4,6-tris(4-phosphonophenyl)pyridine (H6L), was synthesized and used to assemble isostructural barium (1) and strontium (2) phosphonate metal organic frameworks that exhibit fully reversible and selective water-dependent fluorescence red-shift at room temperature

IUPAC recommended experimental methods and data evaluation procedures for the determination of radical copolymerization reactivity ratios from composition data

The IUPAC working group on “Experimental Methods and Data Evaluation Procedures for the Determination of Radical Copolymerization Reactivity Ratios” recommends a robust method to determine reactivity ratios from copolymer composition data using the terminal model for copolymerization. The method is based on measuring conversion (X) and copolymer composition (F) of three or more copolymerization reactions at different initial monomer compositions (f0). Both low and high conversion experiments can be combined, or alternatively only low conversion experiments can be used. The method provides parameter estimates, but can also reveal deviations from the terminal model and the presence of systematic errors in the measurements. Special attention is given to error estimation in F and construction of the joint confidence interval for reactivity ratios. Previous experiments measuring f0 − F or f − X can also be analyzed with the IUPAC recommended method. The influence of systematic errors in the measurements on the reactivity ratio determinations is investigated, including ways to identify and mitigate such errors

Earl T. Carley Interview

Typed summary of interview with Hiram Drache concerning the Chaffee family and life in Amenia, N.D. Includes mention of Herbert F., Carrie T., and Eben Chaffee, other Chaffee family members, the death of H.F. Chaffee, the hotel managed by his parents, the Chaffee's disapproval of dancing and card games, the burning of the grain elevators at Amenia, N.D

James F. Hazard Interview

Typed summary of interview with Hiram Drache concerning the Cooper Ranch with some mention of livestock and farm operations, the Cooper family, and Charles Houghton, Hazard's father-in-law

Nouvelles phases du système Bi

L’étude en fonction de la température du système Bi2O3 - BiPO4 par diffractométrie X et analyse thermique différentielle a permis une nouvelle détermination du diagramme des phases d’équilibre. Elle a montré l’existence de cinq solutions solides et de sept composés définis dont deux seulement avaient été signalés. Cinq composés sont à fusion non congruente, les deux autres subissent une décomposition à l’état solide. Une solution solide y observée dans le domaine de composition maximum 0,10 ≤ x ≤ 0,143 (x = BiPO4/(Bi2O3 + BiPO4) à température ambiante, cristallise dans une maille de type sillénite; elle se transforme successivement en solution solide δ’ puis δ, stables à haute température uniquement.Deux autres solutions solides ε et σ, de symétrie monoclinique, sont respectivement limitées à l’ambiante aux compositions x = 0,25 et x = 0,30 et présentent une sous- maille commune assimilable à une déformation orthorhombique I de la maille cfc de Bi2O3 ; la solution solide ε se transforme en σ au-dessus de 875°C