Cylinder Unit Research Articles

Final report on supplementary comparison EUROMET.M.P-S3 of absolute pressure standards in the barometric range from 80 kPa to 110 kPa

LNE and BIPM compared their pressure standards equipped with 20 cm2 effective area piston–cylinder units in the absolute pressure range from 80 kPa to 110 kPa.The pressure standards, the method for calculating the reference values and the comparison results are presented. The results of the comparison can be considered as satisfactory as the deviations from the reference value are inside the estimated combined uncertainty.Main text.To reach the main text of this Paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by EUROMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Dynamic characteristics of a new damping element based on surface extension principle in nanopore

This paper presents a development of a new damping element which is used as a principle of surface extension in nanopore. The surface extension force of water in hydrophobic nanopore in pressurization process is different from that decompressurization process. This principle is applied to a damping element. The nanopore is constructed by silica gel. A silica gel ball of 100–200 μm ∅ has many nanopores of 7–20 nm ∅ in it. The coated spherical silica gel and water are inserted in a piston–cylinder unit in order to work as a damper. If compression force is added to the piston–cylinder unit (damper), water flows into the nanopore under balance of pressure and surface extension force. If this damper is decompressed, water moves out to the outlet of the pore. The surface extension forces for compression are larger than that of decompression. This difference in force of the surface extension produces a damping energy. Size of the pore, performance of surface extension force, fatigue life of coated material and static characteristics of the damper have already been presented by our group. Hence dynamic characteristics are presented in this paper. Two types of dampers, single cylinder type and double cylinder type, are presented, and energy dissipations of these two dampers are investigated for frequency response and piston stroke. Then the following conclusions are arrived at: (1) Energy dissipation of the single cylinder-type damper is larger than that of the double cylinder-type damper. (2) Amount of energy dissipation is almost constant, even if the input frequency is changed. This characteristic is different from the oil damper. (3) Damping efficiency for unit volume is very high, so large energy can be dissipated by small size damper. (4) Heat does not occur by the dissipation of energy. So characteristics of damping performance do not change by temperature.

Possibilities of diagnosing cavitation in hydraulic systems

Conditions of arising cavitation and experimental investigations of this phenomenon by means of a special vacuum vessel are described. A simulation model of the piston–cylinder unit of a pump with an inclinable cylinder block was used to visualize cavitation in the pump. The results of tests aimed at showing a correlation between the onset of cavitation and an audible diagnostic signal are presented. The suction space of the tested axial-flow multipiston positive-displacement pump with an inclinable cam plate was selected as the most likely place for cavitation to occur. An audible diagnostic signal indicating the onset of cavitation was also detected in the case of a multipiston pump with an inclinable cylinder block. An example of the configuration of an acoustic probe kit for use under industrial conditions is presented.

High light-extraction-efficiency OLED based on photonic crystal slab structures with taper unit cells

To improve the light-extraction-efficiency of OLED, we introduced PCS (Photonic Crystal Slab) structures into the interface of ITO layer and glass substrate. PCS structures with Taper unit cells are proved to be effective in reducing the energy of guided wave trapped in high refractive index material, and an increase of light-extraction-efficiency to 95.26% is gained. This enhancement is much greater than the traditional PCS with cylinder unit cells (60%–70%). Physical mechanisms of light-extraction-efficiency enhancement in these structures are further discussed.

Pressure balance elastic distortion: experiment versus theory

A high resolution gauge is used to determine the change in effective area of a 250 MPa piston–cylinder unit as a function of jacket pressure. These changes are compared with values calculated using a finite element method. The results of the comparison revealed that the jacket pressure seals were applying unexpected forces to the cylinder outer diameter. These forces were modelled in the finite element calculations giving reasonable agreement. Further measurements were made after modifying the jacket seal mounting. The new results showed reasonable agreement at low operating pressures but large disagreement between theory and experiment as the operating pressure approached 250 MPa.

A new instrument for the dimensional characterization of piston–cylinder units

Calculations of the effective area and elastic distortion of piston–cylinder units (PCUs) used to realize fundamental pressure standards require accurate dimensional measurement of the cylindrical geometry of both the piston and the cylinder. A new instrument capable of measuring the diameter and form of PCUs up to 20 mm diameter with target uncertainties of 20 nm is being developed. The first stage of this development is the design and construction of an instrument capable of measuring external diameter using two mutually opposed contact probes mounted on precision translation stages. The positions of the probes are measured continuously using two sub-nanometre displacement measuring laser interferometers. The instrument provides a flexible working platform for future developments.

Calculation of the distortion coefficient and associated uncertainty of PTB and LNE 1 GPa pressure balances using finite element analysis—EUROMET project 463

Results for pressure distortion coefficients (λ) obtained by five national metrology institutes with finite element methods (FEM) for PTB and LNE 1 GPa piston–cylinder units are presented. For the PTB unit they demonstrate good agreement of the FEM and the experimental distortion coefficients but rather large differences in the uncertainties, pressure distributions, gap profiles and piston fall rates. The reasons for differences between the theoretical real-gap and experimental λ obtained for the LNE unit require further clarification. The uncertainty of the gap geometry is identified as the main uncertainty source.

Establishment of an Australian high pressure standard

A controlled-clearance pressure standard has been established at the National Measurement Institute of Australia as a high pressure standard for the realization of the national scale up to 200 MPa. The area of the piston was determined by comparison with a 25 mm diameter piston cylinder assembly that was measured dimensionally and the distortion coefficient was found by calculation and experiment. The controlled-clearance piston gauge was used to calibrate a 100 MPa piston cylinder unit with results agreed to 10 × 10−6 with calibration done at LNE. This 100 MPa unit was used in a regional key comparison with agreement to within 20 × 10−6 of the reference value.

Improvement in Qualification Tests for Fuels and Lubricants. Theoretical Premises

Within the framework of the Interagency Commission (IC) on Allowance for Production and Use of Fuels, Oils, Lubricants, and Special Fluids, qualimetry is based on the use of systems of qualification evaluation methods (SQEM). In accordance with the rules for conducting acceptance tests for these petroleum products for different types of equipment, these systems include fast testing methods in full–scale units, model, single–cylinder units, and in internal combustion engines combined with methods in petroleum product standards (or technical) documentation.

三井-MAN B&W 7S50ME-C : 電子制御エンジンの開発(FP5 レシプロエンジンの環境対応技術)

This paper describes the development of Electronically controlled marine two-stroke diesel engine 7S50ME-C for Tsuneishi Shipyard Sno.1262, and the abstract is made as follows : (1) Generally explained are newly introduced engine components such as Hydraulic Power Supply, Hydraulic Cylinder Unit, Cylinder lub. Oil System, Tacho System and Engine Control System(ECS). (2) Two operation modes are prepared in the operating system as standard. One is "Economy mode", which can comply with the present IMO Nox emission limits, and the other is "Emission mode", which can comply with more strict emission limits. It is possible to change the operation mode by the touch-panel on the Main Operating Panel(MOP). (3) Engine Control System has redundancy with two concepts, one is a complete backup operating system, and Controller called as "Multi Purpose Controller(MPC)", which is used for all control Units, is compatible. (4) ECS controls maximum cylinder pressures for different ambient conditions, such a ship sailing in tropical sea or in arctic sea, by monitoring the scavenging air pressure, in order not to increase the Nox emissions.

A wear testing rig for rapid comparative evaluation of maintenance materials for some oilseed screw press components

The frequent wear of worms and cage linings and the arbitrary refurbishment of these components using any of the locally available welding electrodes has limited the general performance of oilseed screw presses in Nigeria. A low cost rig, which consists of a sample-bearing piston unit, a cylinder unit and a pressure-sensing unit, was designed and developed for carrying out rapid, inexpensive comparative evaluations of the wear performance of locally available electrode fill materials, for use in the maintenance of worn-out screw press components. In addition to demonstrating the potential value of the rig for comparative wear evaluations, preliminary tests on cast iron electrode fill samples, with a palm kernel fruit oilseed meal, showed that for the same operating pressure of 13.7 MPa, increasing the test operating speed from 40 to 85 rpm led to a 12-fold increase in the wear rate of the samples.

Stepped piston modification in the piston manometer of mixed operational principle (simple-piston and re-entrant cylinder system)

The optimization of mixed-principle operation pressure balance consisting of two parts: simple-piston and re-entrant cylinder units is reported. The maximum high pressure corrections for low pressure effective area of the system can be reduced by 50%. The solution was obtained by application of a small reduction (step) of the piston diameter. The modified design is characterized by the performance of the metrological piston of 10 mm2 nominal cross-sectional area with a (1–3) μm inward circumferential step located between the upper (simple piston) and lower (re-entrant) parts of the cylinder in the area where existing intermediate pressure is constant.

A fiber/matrix/composite model with a combined confocal elliptical cylinder unit cell for predicting the effective longitudinal shear modulus

A fiber/matrix/composite model with a combined confocal elliptical cylinder unit cell is proposed for predicting the effective longitudinal shear modulus of fiber reinforced composite materials from the constituent materials. The conformal mapping technique is applied to the model, resulting in closed form solutions which are applicable to extreme types of the inclusion phases (from voids to rigid inclusions), as well as can accommodate a full range of variations in fiber section aspect ratios (from circular fibers to ribbons). A comparison is made with other numerical and experimental results to demonstrate the superiority of the proposed model and the accuracy of the solutions.

New developments in multi-point die-cushion technology

An important and developing topic in sheet metal forming is the improvement of reproducibility of the deep drawing process. One key factor is the control of material flow by the corresponding control of the blankholder pressure. Conventional single or double-action press systems do not offer the means of adjusting a pressure profile that suits a specific part geometry in an optimal way. This causes increased tool run-in times, extended tool change times and high scrap rates for critical forming tasks. This paper describes a new generation of the multi-point-control system consisting of a hydraulic press, a multiple cylinder unit for the blankholding function and flexible forming elements as punch drive. Based on the principles of separating the blankholder function from the slide operation, a part-geometry related blankholder cylinder pattern and providing of centric loading of the forming elements, an improved process stability is achieved. The introduction of a PC-based control system using MS-Windows for the operator interface and a PLC as a software emulation ensures an easy handling of the complex parameter adjustments. An application in the field of stainless steel forming verifies the improvement of process control.

Development of a numerical comparator for protective relaying. I

This paper derives, and explains the use of new numerical comparator concepts. These numerical techniques are new approaches to time domain based relaying algorithms. The initial treatment of the paper concentrates on the generalized idea of a phase comparator and the cylinder unit in particular. The focus in the cylinder unit is to extrapolate for digital relaying purposes, the benefits and characteristics of the well known and widely used relaying unit. The application of the numerical comparator techniques are illustrated with practical units. Distance, directional and over-threshold units illustrate the procedure to obtain protective relaying units using the numerical comparator concepts.

Numerical Analysis of Pressure Distribution in Piston-Cylinder Unit for Accurate Pressure Measurement

Precise and accurate pressure measurements are obtained using deadweight piston gauges. Pressure distribution and elastic distortion in the piston-cylinder unit are the leading factors in determination of effective area. The distortion depends upon the pressure distribution in the clearance between piston and cylinder and those are coupled each other. Considering the viscosity pressure relation of oil and governing flow equation in the clearance, a new numerical iterative algorithm is developed. The disagreement between the monotonous and sharp pressure profiles is an indication that the pressure profile will be different for each piston and cylinder unit due to material variances.

Soil-structure interaction analysis of embedded caisson anchor under tension load : O. E. Hansteen & K. Hoeg, Publikasjon - Norges Geotekniske Institutt, 191, 1994, pp 49–62; reprinted from: BOSS'94, 7th international conference on the behaviour of offshore structures, Massachusetts, 1994, Vol. 1: Geotechnics, ed C. Chryssostomidis & others (Elsevier), 1994, pp 49–62

Capped structural cylinders, vertically embedded in the seafloor, may provide tension capacity for anchorage and bearing capacity for offshore structures. The capacity of such inverted buckets to resist combinations of static and cyclic loads may be predicted by reliable computational procedures. This has been demonstrated by model tests and field performance observations. The emphasis in this paper is on the soil-structure interaction and the determination of contact stresses between the embedded cylinder and the inside and outside soil. These stresses are required for the structural design. A 3-dimensional finite element program is used to analyze a one- cylinder unit embedded in soft clay. The anchor is subjected to a cyclic live load corresponding to that for a tension leg platform. In addition to the magnitude and distribution of the control stresses, the results of the analyses show how the anchor pull is shared among the four different kinds of load carrying mechanisms, (1) vertical underpressure under the cylinder top cap, (2) inside and (3) outside shear along the skirt walls, and (4) underpressure under the skirt tip circumference. The load sharing varies with the applied tension load level due to the non-linear soil behaviour, and it is very sensitive to the assumed bulk modulus (or Poisson's ratio) for the undrained soil.

Method of stowing a worked-out space

method of mining economic minerals. In developing previously presented studies of the dense packing method for a worked-out space with barren rock [2] the present article considers a method for stowing long small-diameter tunnels. This method is based on the fact that the stowing material 1 (Fig. 1) is placed in a closed sealed channel 2. The mouth of the channel is covered with a sealed diaphragm 3 and compressed gas is supplied to its inside which fills the pore space 4 of the projected material. After rapid opening of the diaphragm a two-phase stream consisting of gas and stowing material is directed from the mouth into the exhausted working. In order to perform experimental studies of the process of projecting a two-phase stream into a closed bounded space in the form of a tunnel a unit was created whose layout is presented in Fig. 2. Several pairs of steel tubes closed from one direction and having a flange in the other were used as the discharge channel 1 and receiving channel 2. The tubes were of different shape and ratio of internal volumes. In the original state the discharge channel was filled with quartz sand and it was joined coaxially with the receiving channel through a sealing membrane made of Dacron 3. Opening of the sealing membrane was accomplished by heating a nichrome filament 4 fed from a supply unit 5. Filling of the pore space of the filler was accomplished by feeding compressed air from a cylinder unit 6 through a pneumatic flap 7. Monitoring of the initial pressures in the discharge and receiving channels was accomplished by manometers 8, 9. The change in pressure over the length of channels during the process was monitored by nine pressure gages DD-10 which were placed equidistantly along the channel length and a signal was fed through a pressure indicator to a loop oscillograph N-145. In the course of studies the original pressure in the discharge Pd and receiving Pr channels, the current pressure in different sections over the length of channels Pi (index i corresponds to the letters for gages in Fig. 2), equilibrium pressure PR in the system after the end of the process, the weight of residue material in the discharge channel n~, and the weight transferred to the receiving chaimel m r were measured. By equilibrium pressure PR we understand the pressure established in the system of closed channels after the end of the process. With a known value for the porosity of loose material II it may also be determined by the equation

Balancing Method for a Rigid Rotor Considering Constraint of the Correction Mass.

In balancing the rigid rotor, correction masses which are calculated by the least squares method using a performance function defined as a sum of squares of a residual vibration are often undesirable values. In the actual correction process, the magnitude of the correction masses which can be put on or cut off from the rotor is constrained by the structure and the shape of the rotor or the method of the process. In this study, an improved balancing method which can reduce the correction masses is proposed. In this balancing method, both residual vibration and correction mass are adopted as parameters of the performance function. The effectiveness of the proposed balancing method is confirmed by computer simulation and experiment using the rotating cylinder unit of the VTR.

An Automatic Adjustment System for VCR Magnetic Heads on Cylinder Units

An automatic adjustment system for VCR magnetic heads on a rotating cylinder unit has been newly developed. Magnetic head setting errors affect reconstructed image qualities. Extremely important head positioning errors are: 1) Setting angle error for two symmetrically positioned heads. 2) Rotational angle error for every individual head, in regard to a setting screw axis. 3) Distances head tips protrude from a cylinder edge. The pertinent technical features for the system are high speed and highly accurate image processing algorithms, to determine head positions using inter-ferometric head images and very precise mechanisms and algorithms to adjust head positions, even when head slipping and elastic deformations occur. Adjustment speed for the system is 30 sec/unit. One machine corresponds to three skilled operators in total productivity.