Specification for steel globe valves, globe stop and check valves and lift type check valves

This paper aims to present the design, fabrication and test of a novel piezoelectrically actuated, check valve embedded micropump having the advantages of miniature size, light weight and low power consumption. The micropump consists of a piezoelectric actuator, a stainless steel chamber layer with membrane, two stainless steel channel layers with two valve seats, and a nickel check valve layer with two bridge-type check valves. The check valve layer was fabricated by nickel electroforming process on a stainless steel substrate. The chamber and the channel layer were made of the stainless steel manufactured using the lithography and etching process based on MEMS fabrication technology. The effects of check valve thickness, operating frequency and back pressure on the flow rate of the micropump are investigated. The micropump with check valve 20 μm in thickness obtained higher output values under the sinusoidal waveform of 120 Vpp and 160 Hz. The maximum flow rate and backpressure are 1.82 ml/min and 32 kPa, respectively.

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Research on Open and Close Characteristics of Passive Shuttle-Type Anti-Water-Attack Check Valve

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.474-476.2290 ◽

2011 ◽

Vol 474-476 ◽

pp. 2290-2295

Author(s):

Bei Ping Xiang ◽

Guo Fu Yin ◽

Xiang Wei Zeng ◽

Hong Bin Zang

Keyword(s):

Flow Field ◽

Rapid Change ◽

Check Valve ◽

Pressure Change ◽

Pipeline System ◽

Hydraulic Damper ◽

Pressure Pipeline ◽

Set Up ◽

Opening And Closing ◽

Type Check

Water-attack is very harmful to pressure pipeline system security. Passive shuttle-type anti-water-attack check valve can adjust its open and close time by hydraulic damper, and cushion the rapid change of liquid momentum in order to protect the pumps and pipelines. The structure and working principle of this passive check valve are introduced, and the dynamics model is set up. The opening and closing characteristics of the model is analyzed, and simulation comparison is done between the flow field and pressure change laws of shuttle-type check valve and those of swing check valve. The simulation result shows that the hydraulic damper works very well, the flow field of passive shuttle-type check valve is symmetrical, the forces acting on the shuttle is balanceable, and shuttle-type check valves can replace swing check valves in many fields.

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Type Checking Semantic Functions in ASDF

BRICS Report Series ◽

10.7146/brics.v11i35.21860 ◽

2004 ◽

Vol 11 (35) ◽

Author(s):

Jørgen Iversen

Keyword(s):

Side Effects ◽

Programming Languages ◽

Type System ◽

Type Checking ◽

Semantic Function ◽

Semantic Framework ◽

Language Constructs ◽

Type Check

When writing semantic descriptions of programming languages, it is convenient to have tools for checking the descriptions. With frameworks that use inductively defined semantic functions to map programs to their denotations, we would like to check that the semantic functions result in denotations with certain properties. In this paper we present a type system for a modular style of the action semantic framework that, given signatures of all the semantic functions used in a semantic equation defining a semantic function, performs a soft type check on the action in the semantic equation.<br /> <br />We introduce types for actions that describe different properties of the actions, like the type of data they expect and produce, whether they can fail or have side effects, etc. A type system for actions which uses these new action types is presented. Using the new action types in the signatures of semantic functions, the language describer can assert properties of semantic functions and have the assertions checked by an implementation of the type system.<br /> <br />The type system has been implemented for use in connection with the recently developed formalism ASDF. The formalism supports writing language definitions by combining modules that describe single language constructs. This is possible due to the inherent modularity in ASDF. We show how we manage to preserve the modularity and still perform specialised type checks for each module.

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A STATISTICAL ANALYSIS OF TEMPERATURE OSCILLATIONS ON A FLAT-PLATE OSCILLATING HEAT PIPE WITH TESLA-TYPE CHECK VALVES

Frontiers in Heat Pipes ◽

10.5098/fhp.v2.3.3002 ◽

2012 ◽

Vol 2 (3) ◽

Author(s):

H.B. Ma ◽

Scott Thompson

Keyword(s):

Statistical Analysis ◽

Flat Plate ◽

Heat Pipe ◽

Oscillating Heat Pipe ◽

Temperature Oscillations ◽

Type Check

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A framework for improving error messages in dependently-typed languages

Open Computer Science ◽

10.1515/comp-2019-0001 ◽

2019 ◽

Vol 9 (1) ◽

pp. 1-32 ◽

Cited By ~ 1

Author(s):

Joseph Eremondi ◽

Wouter Swierstra ◽

Jurriaan Hage

Keyword(s):

Programming Languages ◽

Type System ◽

Higher Order ◽

Type Checking ◽

Unification Algorithm ◽

Implicit Arguments ◽

Unification Problem ◽

Heuristic Analysis ◽

Type Check ◽

Typed Languages

AbstractDependently-typed programming languages provide a powerful tool for establishing code correctness. However, it can be hard for newcomers to learn how to employ the advanced type system of such languages effectively. For simply-typed languages, several techniques have been devised to generate helpful error messages and suggestions for the programmer. We adapt these techniques to dependently-typed languages, to facilitate their more widespread adoption. In particular, we modify a higher-order unification algorithm that is used to resolve and type-check implicit arguments. We augment this algorithm with replay graphs, allowing for a global heuristic analysis of a unification problem-set, error-tolerant typing, which allows type-checking to continue after errors are found, and counter-factual unification, which makes error messages less affected by the order in which types are checked. A formalization of our algorithm is presented with an outline of its correctness. We implement replay graphs, and compare the generated error messages to those from existing languages, highlighting the improvements we achieved.

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Performance and Design of Plug-Type Check Valves

Proceedings of the Institution of Mechanical Engineers ◽

10.1243/pime_proc_1982_196_006_02 ◽

1982 ◽

Vol 196 (1) ◽

pp. 47-56 ◽

Cited By ~ 3

Author(s):

J Kubie

Keyword(s):

High Pressure ◽

Power Plant ◽

Dynamic Behaviour ◽

Plant System ◽

Flow Recirculation ◽

Type Check

Plug check valves are frequently used in high pressure systems where parallel pump operations are envisaged, in order to prevent flow recirculation through the out-of-service pump. Serious operational problems are sometimes encountered with these valves during pump changeovers. Full equations of the dynamic behaviour of the plug check valves are derived and results are obtained for their performance in a typical power plant system. Criteria for the design of the plug check valves are also developed.

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